-
Introduction to
Physiology
Introduction
Physiology
is
the
study
of
the
functions
of
living
matter.
It
is
concerned
with
how
an
organism
performs
its
varied
activities:
how
it
feeds,
how
it
moves,
how
it
adapts
to
changing
circumstances,
how
it
spawns new generations.
The subject is vast and embraces the whole of
life. The success of physiology in
explaining how organisms perform their
daily
tasks
is
based
on
the
notion
that
they
are
intricate
and
exquisite
生理学简介
介绍
生理学是研究生物体功能的科学
。它
研究生物体如何进行各种活动，如何饮食，
如何运动，
如何适应不断改变的环境，
如何
繁殖后代。
这门学科包罗万象，
涵盖了生物
体整个
生命过程。生理学成功地解释了生
物体如何进行日常活动，基于的观点是生
machines
whose
operation
is
governed
by
the
laws
of
physics
and
chemistry.
Although some processes are similar
across the whole spectrum of
biology—the replication of the genetic
code for or example—many are
specific
to particular groups of organisms. For this reason
it is necessary
to divide the subject
into various parts such as bacterial physiology,
plant
physiology, and animal
physiology.
To study how an
animal works it is first necessary to know how it
is
built. A full appreciation of the
physiology of an organism must therefore
be based on a sound knowledge of its
anatomy. Experiments can then be
carried
out
to
establish
how
particular
parts
perform
their
functions.
Although there
have been many important physiological
investigations on
human
volunteers,
the
need
for
precise
control
over
the
experimental
conditions has
meant that much of our present physiological
knowledge
has been derived from studies
on other animals such as frogs, rabbits, cats,
and
dogs.
When
it
is
clear
that
a
specific
physiological
process
has
a
common
basis
in
a
wide
variety
of
animal
species,
it
is
reasonable
to
assume
that
the
same
principles
will
apply
to
humans.
The
knowledge
gained
from
this
approach
has
given
us
a
great
insight
into
human
physiology
and
endowed
us
with
a
solid
foundation
for
the
effective
treatment of many diseases.
The
building
blocks
of
the
body
are
the
cells,
which
are
grouped
together
to
form
tissues.
The
principal
types
of
tissue
are
epithelial,
connective,
nervous,
and
muscular,
each
with
its
own
characteristics.
Many connective tissues have relatively
few cells but have an extensive
extracellular
matrix.
In
contrast,
smooth
muscle
consists
of
densely
packed layers of
muscle cells linked together via specific cell
junctions.
Organs such as the brain,
the heart, the lungs, the intestines, and the
liver
are formed by the aggregation of
different kinds of tissues. The organs are
themselves parts of distinct
physiological systems. The heart and blood
vessels form the cardiovascular system;
the lungs, trachea, and bronchi
together with the chest wall and
diaphragm form the respiratory system;
the skeleton and skeletal muscles form
the musculoskeletal system; the
brain,
spinal cord, autonomic nerves and ganglia, and
peripheral somatic
nerves form the
nervous system, and so on.
Cells
differ
widely
in
form
and
function
but
they
all
have
certain
common
characteristics.
Firstly,
they
are
bounded
by
a
limiting
membrane, the plasma membrane.
Secondly, they have the ability to break
物体好比是结构复杂而灵巧的机器，其操
作受物理和化学规律控制。
尽管从生物学整个范畴看，生物体某
些活动过程是相
似的
——
如基因编码的复
制
——
但许多过程还是某些生物体群组特
有的。鉴于
此有必要将这门学科分成不同
部分研究，
如细菌生理学、
植物生理学和动
物生理学。
要研究一种动物如何活动，首先需要
了解它的构成。要充分了解一个生物体的<
/p>
生理学活动就必须掌握全面的解剖学知
识。一个生物体的各部分起
着什么作用可
通过实验观察得知。尽管我们对志愿者进
行了许多
重要的生理调查，但是实验条件
需要精确控制，所以我们当前大多生理知
识还是源于对其它动物如青蛙，
兔子，
猫和
狗等的研究。当我们明确大多数动物物种
的特定生理过程存在共同之处时，
相同的
生理原理适用于人类也是合理的。通过这
种方法，
我们获得了大量的知识，
从而让我
们对人类生
理学有了更深入的了解，为我
们有效治疗许多疾病提供了一个坚实的基
< br>础。
机体的基本组成物质是细胞，细胞结
合在一起形成组织。组织的基本类型有上
皮组织，
结
缔组织，
神经组织和肌组织，
每
类组织
都有各自的特征。许多结缔组织中
细胞量相对较少，但是有大量的细胞外基
质。
相比而言，
光滑的肌组织由大量密密麻
麻的肌细胞通过特定的细胞连接组成。各
种器官如脑，
< br>心脏，
肺，
小肠和肝等由不同
种
类的组织聚集而成。这些器官是不同生
理系统的组成部分。心脏和血管组成心血
管系统；
肺，
器官，
支
气管，
胸壁和膈肌组
成呼吸系统；骨骼和骨骼肌组成骨骼肌系<
/p>
统；
大脑，
脊髓，
自主神经和神经中枢以及
周围躯体神经组成神经系统等等。
细胞在形体和功能上差异很大，但是
down large molecules to smaller ones to
liberate energy for their activities.
Thirdly, at some point in their life
history, they possess a nucleus which
contains genetic information in the
form of deoxyribonucleic acid (DNA).
Living
cells
continually
transform
materials.
They
break
down
glucose and fats to provide energy for
other activities such as motility and
the synthesis of proteins for growth
and repair. These chemical changes
are
collectively called metabolism. The breakdown of
large molecules to
smaller
ones
is
called
catabolism
and
the
synthesis
of
large
molecules
from smaller ones anabolism.
In
the
course
of
evolution,
cells
began
to
differentiate
to
serve
它们有某些共同的特征。
第一，
它们由限制
膜包被，
即细胞质膜
；
第二，
细胞有把大分
子分解为小分子
来释放活动所需能量的能
力；
第三，
在
生命过程中某个阶段，
细胞体
内存在一个以脱氧核糖核酸
(DNA)
形式包
含基因信息的细胞核。
活体细胞不断转化物质。它们为其它
活动
提供能量分解葡萄糖和脂肪，比如自
身生长和修复所需的蛋白质运动和合成。
这些化学变化统称为新陈代谢。把大分子
different
functions. Some developed the ability to contract
(muscle cells),
others
to
conduct
electrical
signals
(nerve
cells).
A
further
group
developed the ability
to secrete different substances such as hormones
or
enzymes.
During
embryological
development,
this
process
of
differentiation
is
re-enacted
as
many
different
types
of
cell
are
formed
from
the fertilized egg.
Most
tissues
contain
a
mixture
of
cell
types.
For
example,
blood
consists of red cells, white cells, and
platelets. Red cells transport oxygen
around the body. The white cells play
an important role in defense against
infection and the platelets are vital
components in the process of blood
clotting. There are a number of
different types of connective tissue but all
are
characterized
by
having
cells
distributed
within
an
extensive
noncellular matrix. Nerve tissue
contains nerve cells and glial cells.
The Principal Organ Systems
The cardiovascular system
The cells of large multicellular
animals cannot derive the oxygen and
nutrients they need directly from the
external environment. The oxygen
and
nutrients must be transported to the cells. This
is one of the principal
functions of
the blood, which circulates within blood vessels
by virtue of
the pumping action of the
heart. The heart, blood vessels, and associated
tissues form the cardiovascular
system.
The heart consists
of four chambers, two atria and two ventricles,
which
form
a
pair
of
pumps
arranged
side
by
side. The
right
ventricle
pumps deoxygenated
blood to the lungs where it absorbs oxygen from
the
air, while the left ventricle pumps
oxygenated blood returning from the
lungs to the rest of body to supply the
tissues. Physiologists are concerned
with establishing the factors
responsible for the heartbeat, how the heart
pumps the blood around the circulation,
and how it is distributed to perfuse
the tissues according to their needs.
Fluid exchanged between the blood
plasma and the tissues passes into the
lymphatic system, which eventually
drains back into the blood.
The respiratory system
The
energy required for performing the various
activities of the body
is ultimately
derived from respiration. This process involves
the oxidation
of foodstuffs to release
the energy they contain. The oxygen needed for
分解为小分子的过程称为分解代谢，小分
子合成大分子的过程称为合成
代谢。
细胞在进化过程中不断分化进行不同
< br>的功能活动。
有些细胞具有收缩能力
（如肌
细胞）
，有些可以传导电信号（如神经细
胞）
。进一步进化的细胞能够分泌不同物质
如荷尔蒙
（如内分泌细胞）
或酶。
胚胎发育
过
程中，分化的过程由于很多不同细胞来
源于受精卵而再次发生。
大多数组织包含有不同的细胞类型。
比如，血液中含红细胞，白
细胞和血小板。
红细胞运输全身的氧气。白细胞在抵御感
染时起
重要作用，血小板是血液凝集过程
中重要的成分。结缔组织有多种不同类型，
但有一个共同特征，即细胞分布在丰富的
细胞外基质中。神经组织含神经细
胞和神
经胶质细胞。
主要的器官系统
心血管系统
大型多细胞动物体的细胞
不能从外界
环境中获取直接所需的氧气和营养物质。
这些氧气和
营养物质必须转运到细胞。这
是血液的主要功能之一，血液凭借心脏的
< br>泵血作用在血管内流动循环。
心脏、
血管和
结缔组织组成了心血管系统。
心脏包括四个腔，两
个心房和两个心
室构成了一对并排存在的泵。右心室将脱
氧的血
液泵至肺中，肺中的血液吸收空气
中的氧气，而左心室把从肺回流来的有氧
血液泵出至身体其它部位，供应给各组织。
生理学家研究促使心脏跳动的因素
，心脏
如何泵送血液使其循环，心脏如何根据各
组织所需分配血
液。血浆和组织间的流动
液体交换流入淋巴系统，最终回流到血液
中。
this process
is absorbed from the air in the lungs and carried
to the tissues
by the blood. The carbon
dioxide produced by the respiratory activity of
the tissues is carried to the lungs by
the blood in the pulmonary artery
where
it is excreted in the expired air. The basic
questions to be answered
include the
following: How is the air moved in and out of the
lungs? How
is
the
volume
of
air
breathed
adjusted
to
meet
the
requirements
of
the
body? What limits the
rate of oxygen uptake in the lungs?
呼吸系统
机体进行各项活动所需的能
量最终来
源于呼吸。
这一过程包括食物
（主要是糖类
和脂肪）
的氧化，
释放它
们所含的能量。
这
一过程中，
氧气来自
于肺中的空气，
经由血
液到达全身各组织。组织呼吸活动中释放
的二氧化碳由肺动脉中的血液运送至肺，
The
digestive system
然后呼气排出体外。需回答的基本问题如
The
nutrients needed by the body are derived from the
diet. Food is
下：空气是如何进出肺的？呼吸的空气量
taken
in
by
the
mouth
and
broken
down
into
its
component
parts
by
如何适应机体所需？限制肺吸收氧气频率
enzymes
in
the
gastrointestinal
tract.
The
digestive
products
are
then
的因素是什么？
absorbed
into the blood across the wall of the intestine
and pass to the liver
消化系统
via the portal vein. The liver makes
nutrients available to the tissues both
for their growth and repair and for the
production of energy. In the case of
机体所需营养物质来源于饮食。食物
the
digestive
system,
key
physiological
questions
are:
How
is
food
经口腔进入体内，在胃肠道内经酶将其分
ingested?
How is it broken down and digested? How are the
individual
解成小分子物质。这些消化物通过肠壁吸
nutrients
absorbed? How is the food moved through the gut?
How are the
收入血液，
通过门静脉进入肝脏。<
/p>
经肝脏作
indigestible remains
eliminated from the body?
用后
，这些营养物质能够满足组织生长修
复及能量需求。
在消化系统
部分，
重要的生
The kidneys and
urinary tract
理学问题是：食物是如何消化的？食物如
The chief
function of the kidneys is to control the
composition of the
何被个体分解消化？个体营养物质如何吸
extracellular fluid. In the course of
this process, they also eliminate non-
收
？食物如何在肠内转运的？未消化的残
volatile waste
products from the blood. To perform these
functions, the
留如何从体内排出？
kidneys produce urine of variable
composition which is temporarily stored
泌尿系统
in the
bladder before voiding. The key physiological
questions in this case
are: how do the
kidneys regulate the composition of the blood? How
do
肾脏主要功能是控制细胞外液体的形
they
eliminate
toxic
waste?
How
do
they
respond
to
stresses
such
as
成。
在这一过程中，
肾脏也会把不可挥
发的
dehydration? What mechanisms allow
the storage and elimination of the
废物排出去。为行使这一功能，在排出之
urine?
前，肾脏产生含有各种成分的尿液并将其
暂时储存在膀胱中。这一部分主要的生理
The reproductive
system
学问题是：肾脏如何调节血液中的成分？
Rep
roduction
is
one
of
the
fundamental
characteristics
of
living
如何排出有毒废物？如何应对像脱水这样
organisms.
The gonads produce specialized sex cells known as
gametes.
的应激反应？以及尿液可以存储和排出体
At the
core of sexual reproduction is the creation and
fusion of the male
外的机制是什么？
and female gametes, the sperm and ova
(eggs), with the result that the
生殖系统
genetic
characteristics of two separate individuals are
mixed to produce
offspring that differ
genetically from their parents.
生殖是活生物体的一个基本特征。生
殖腺产生专门的性细胞，
< br>被称为配子。
性生
The
musculoskeletal system
殖的核心是雌雄配子即精子和卵子的产生
This
consists of the bones of the skeleton, skeletal
muscles, joints,
和融合，因此两个独立个体的基因特征融
and their
associated tissues. Its primary function is to
provide a means of
合而产生一个基因上与双亲不同的后代。
movement,
which
is
required
for
locomotion,
for
the
maintenance
of
运动系统
posture, and for breathing. It also
provides physical support for the internal
organs. Here the mechanism of muscle
contraction is a central issue. The
这一系
统由骨、
骨骼肌、
关节和它们的
end
ocrine and nervous systems.
相关组织组成。其主要功能是提供运动需
要，
维持姿势及呼吸运
动。
它也为内脏器官
The endocrine and
nervous systems
提供物理支持。
这一部分，
肌肉收缩机制是
The
activities of the different organ systems need to
be coordinated
and regulated so that
they act together to meet the needs of the body.
Two
coordinating systems have evolved:
the nervous system and the endocrine
system. The nervous system uses
electrical signals to transmit information
very rapidly to specific cells. Thus
the nerves pass electrical signals to the
skeletal
muscles
to
control
their
contraction.
The
endocrine
system
secretes chemical agents, hormones,
which travel in the bloodstream to
the
cells upon which they exert a regulatory effect.
Hormones play a major
role
in
the
regulation
of
many
different
organs
and
are
particularly
important
in
the
regulation
of
the
menstrual
cycle
and other
aspects
of
reproduction.
The
immune system provides the body’s defenses against
infection
both
by
killing
invading
organisms
and
by
eliminating
diseased
or
damaged cells.
Although it is helpful to study how
each organ performs its functions,
it
is
essential
to
recognize
that
the
activity
of
the
body
as
a
whole
is
dependent on the intricate interactions
between the various organ systems.
If
one
part
fails,
the
consequences
are
found
in
other
organ
systems
throughout the whole
body. For example, if the kidneys begin to fail,
the
regulation of the internal
environment is impaired which in turn leads to
disorders of function
elsewhere.
主要问题。
内分泌系统和神经系统
不同器官系统
的活动需要协作和调
节，
以便共同作用满足机体需要。
人体有两
大调节系统：
神经系统和内分泌系统。
神经
系统通过电信号迅速将信息传导给特定细
< br>胞。这样神经将电信号传递给骨骼肌以控
制收缩。内分泌系统分泌化学物质
―
激素。
激素通过血流到达施与调节作用的细
胞。
激素在许多不同器官中起着重要作用，在
月经期调节和其它
生殖方面尤其重要。
免疫系统通过杀死入侵的有机体，清
除致病或损伤细胞为机体提供防御功能。
虽然研究各器官如何行使功能很有益
处，但我们必须认识到机体作为一个整体
所做的活动依赖于各器官系统间错综复杂
的相互作用。
如果一部分无法正常工作，
全
身其它器官系统也会受到影响
。
例如，
如果
肾脏出现问题，
内部环境的调节受损，
结果
导致其它器官系统功
能紊乱。
Homeostasis
Complex mechanisms are at work to
regulate the composition of the
extracellular
fluid
and
individual
cells
have
their
own
mechanisms
for
regulating
their
internal
composition.
The
regulatory
mechanisms
stabilize the internal environment
despite variations in both the external
world and the activity of the animal.
The process of stabilization of the
internal environment is called
homeostasis and is essential if the cells of
the body are to function
normally.
Taking
one
example,
the
beating
of
the
heart
depends
on
the
rhythmical contractions
of cardiac muscle cells. This activity depends on
electrical signals which, in turn,
depend on the concentration of sodium
and potassium ions in the extracellular
and intracellular fluids. If there is
an excess of potassium in the
extracellular fluid, the cardiac muscle cells
become too excitable and may contract
at inappropriate times rather than
in a
coordinated manner. Consequently, the
concentration of potassium in
the
extracellular fluid must be kept within a narrow
range if the heart is to
beat
normally.
稳态
各种复杂机制共同作用调节细胞外液
的形成，不同个体细胞有自身机制调
节内
在组成成分。尽管外界环境和动物活动不
停变化，调节机制
维持着体内环境的稳定。
内部环境的稳定被称为稳态，它是机体能
够正常发挥作用所必须的。
例如，心脏的跳动依赖于心肌细
胞有
节律的收缩。
这一活动依赖于电信号，
而电
信号反过来依赖存在于细胞外和细胞内液
体中钠和钾离
子的浓度。如果细胞外液中
钾离子过多，
心肌细胞兴奋性增强，
可能出
现不规律的收缩。
因此，
要维持心脏正常跳
动，细胞外液中钾离子的浓度就必须控制
在一定范围内。
机体如何调节物质成分
平衡的概念
一天中，一个成人需要消
耗约
1
千克
食物，
2~3
升液体。
以一个月计算，
这
相当
于约
30
千克食物，
60~90
升液体。然而，
一般来说，
机体体重是基本不变的。
这类个
体可以说处于平衡状
态。食物和液体的摄
入量相当于正常机体活动消耗的能量加上
尿
液和粪便中丢失的能量。在一些情况下，
How Does The Body
Regulate Its Own Composition?
The concept of balance
In
the course of a day, an adult consumes
approximately 1 kg of food
and drinks
2~3 liters of fluid. In a month, this is
equivalent to around 30
kg of food and
60~90 liters of fluid. Yet, in general, body
weight remains
remarkably constant.
Such individuals are said to be in balance; the
intake
of food and drink matches the
amounts used to generate energy for normal
bodily activities plus the
losses in urine and feces. In some circumstances,
such as starvation, intake does not
match the needs of the body and muscle
tissue
is
broken
down
to
provide
glucose
for
the
generation
of
energy.
Here,
the
intake
of
protein
is
less
than
the
rate
of
breakdown
and
the
individual is said to have a negative
nitrogen balance. Equally, if the body
tissues are being built up, as is the
case for growing children, pregnant
women
and
athletes
in
the
early
stages
of
training,
the
daily
intake
of
protein is greater than the normal body
turnover and the individual is in
positive nitrogen
balance.
This concept of
balance can be applied to any of the body
constituents
including
water
and
salt
and
is
important
in
considering
how
the
body
regulates its own composition. Intake
must match requirements and any
excess
must be excreted for balance to be maintained.
Additionally, for
each chemical
constituent of the body there is a desirable
concentration
range,
which
the
control
mechanisms
are
adapted
to
maintain.
For
example, the concentration of glucose
in the plasma is about 4~5mmol/L
between meals. Shortly after a meal,
plasma glucose rises above this level
and this stimulates the secretion of
the hormone insulin by the pancreas,
which
acts
to
bring
the
concentration
down.
As
the
concentration
of
glucose falls, so does the secretion of
insulin. In each case, the changes in
the circulating level of insulin act to
maintain the plasma glucose at an
appropriate level. This type of
regulation is known as negative feedback.
During the period of insulin secretion,
the glucose is being stored as either
glycogen or fat.
A negative feedback loop is a control
system that acts to maintain the
level
of
some
variable
within
a
given
range
following
a
disturbance.
Although
the
example
given
above
refers
to
plasma
glucose,
the
basic
principle
can
be
applied
to
other
physiological
variables
such
as
body
temperature, blood pressure, and the
osmolality of the plasma. A negative
feedback loop requires a sensor of some
kind that responds to the variable
in
question but not to other physiological variables.
Thus an osmoreceptor
should
respond
to
changes
in
osmolality
of
the
body
fluids
but
not
to
changes in
body temperature or blood pressure. the
information from the
sensor must be
compared in some way with the desired level by
some form
of comparator. if the two do
not match ,an error signal is transmitted to an
effector,
a
system
that
can
act
to
restore
the
variable
to
its
desired
level
.these features of negative feedback can be
appreciated by examining
a
simple
heating
system .the
controlled
variable
is
room
temperature,
which is sensed
by a thermostat. the effector is a heater of some
kind .when
the room temperature falls
below the set point, the temperature difference
is detected by the thermostat which
switches on the heater .this heats the
room until the temperature reaches the
per set level whereupon the heater
is
switched off.
To summarize,
the body is actually a social order of about 100
trillion
cells
organized
into
different
functional
structures,
some
of
which
are
called organs. each
functional structures its share to the maintenance
of
homeostatic
conditions
in
the
extracellular
fluid,
which
is
called
the
internal long as normal
conditions are maintained in this
如饥饿状态
，摄入量与机体所需量并不相
当，
肌组织断裂，
提供葡萄糖产生能量。
蛋
白质的摄入低于肌组织断裂的
速度，机体
处于负氮平衡。
同样地，
如
果机体组织正处
于生长期，
如生长期的儿童，
< br>孕妇和早期训
练阶段的运动员，那么蛋白质的日常摄入
量
比正常机体所需要的多。
相反，
此时个体
处于
正氮
平衡。
< br>平衡的概念可以应用到机体的任何构
成成分上，
包括水和
盐，
而且平衡在机体调
节其自身成分上是非常重要的。摄入必须
等于所需，
为维持机体平衡，
任何多余
的能
量都必须排出。
此外，
因为机体的
每种化学
成分都有一个可取的浓度范围，控制机制
维持这个范围
。
例如，
两餐间血糖浓度大约
为
4~5mmol/L
。
进食后不久，
血糖含量超过
这一范围，刺激胰腺分泌胰岛素，降低浓
< br>度。
随着葡萄糖浓度的下降，
胰岛素分泌减
少。
在此情况下，
循环胰岛素水平的改变都
是为了使血浆中的葡萄糖维持在一个合适
的范围内。
这种调节称为负反馈机制。
在胰
岛素分泌期间，葡萄糖像肝
糖原或脂肪一
样被储存。
负反馈调节
是在机体出现紊乱时，将
一些变量控制在限定范围内的一个控制系
统。
虽然上面的例子讲到血糖，
但这一基本
< br>原则可以应用到其它生理变量中如体温、
血压和血浆的渗透浓度。负反馈调节需要
一种能对不确定的变量做出反应而对其它
生理变量不应答的传感
器。
因此，
渗透压感
受器应该能对机体
体液渗透的变化而不是
体温和血压的变化产生应答。感受器传递
的信息必须和理想水平
（系统的调定点）
以
比较者的身份，
以某种方式进行比较。
如果
两者不相符，一个错误信号就会传递给效
应器，效应器是一种能使变量保持在理
想
水平的系统。负反馈的这些特点可以通过
检测一种简单的加热
系统来理解。被控制
的变量是室温，它可以由一个温度计检测
到
，
效应器是一种加热器。
当室温降低到调
定点以下时，温度计就可以监测到温度的
变化而开启加热器，
对室内进行加温，
直到
室温升高到先前调好的调定点，加热器关
闭。
总而言之，机体实际上是由
100
万亿
细胞有序组成了不同的功能结构
，其中一
些被称为器官。每个功能结构都在维持细
胞外液稳态方
面发挥其作用，这称之为内
internal
environment ,the cells of the body continue to
live and function
properly.
Each
cell
benefits
from
homeostasis,
and
in
turn,
each
cell
contributes
its
share
toward
the
maintenance
of
homeostasis.
This
reciprocal
interplay
provides
continuous
automaticity
of
the
body
until
one or more functional
systems lose their ability to contribute their
share
of function. When this happens,
all the cells of the body suffer. Extreme
dysfunction leads to death; moderate
dysfunction leads to sickness.
环境。
只
要内部环境处于正常状态，
机体细
胞继续生存并正常运行。每个
细胞都从稳
态中获益，
反过来，
每个细
胞都为稳态做出
贡献。这种相互作用促使机体持续自主运
行，直
至一个或多个功能系统不能正常运
转。
此时，
< br>机体所有细胞都会受损。
功能极
度异常会导致死亡，轻微
的功能异常导致
疾病的发生。
The Other Side of
Antibiotics
Antibiotics have
eliminated or controlled so many infectious
diseases
that virtually everyone has
benefited from their
use at
one time or another.
Even without such
personal experience, however, one would have to be
isolated indeed to be
unaware of the virtues, real and
speculative, of these
“miracle” drugs.
The American press, radio, and television
have
done a
good
job
of
reporting
the
truly
remarkable
story
of
successes
in
the
chemical war on germs.
What’s more, any
shortcomings on their part have
been more than made up for by the
aggressive public relations activity of
the pharmaceutical
companies which manufacture and sell
antibiotics.
In
comparison,
the
inadequacies
and
potential
dangers
of
these
remarkable
drugs
are
much
less
widely
known. And
the
lack
of
such
knowledge
can
be
bad,
especially
if
it
leads
patients
to
pressure
their
doctors
into
prescribing
antibiotics
when
such
medication
isn’t
really
needed, or leads them
to switch doctors until they find one who is, so
to
speak,
antibiotics-minded.
Because the good side of the
antibiotics story is so very well-known,
there seems more point here to a review
of some of
the immediate and
long-range problems that can come from
today’s casual use of these drugs.
It
should
be
made
clear
in
advance
that
calamities
from
the
use
of
antibiotics
are
rare
in
relation
to
the
enormous
amounts
of
the
drugs
administered. But the
potential hazards, so little touched on generally,
do
need
a
clear
statement.
The
antibiotics
are
not,
strictly
speaking,
exclusively
prescription drugs. A number of them are permitted
in such
over-the-counter products as
nasal sprays,
lozenges,
troches, creams, and
ointments. Even if
these products do no harm, there is no point
whatsoever
in
using
them.
If
you
have
an
infection
serious
enough
to
warrant
the
launching
of
chemical
warfare,
you
need
much
bigger
doses
of
the
antibiotics
than any of the non-prescription products are
allowed to
contain.
Over-the-counter
products,
however,
account
for
only
a
small
percentage of total
antibiotics production. It is
the
prescription
dosages
that
give
people
trouble.
These
drugs—even
allowing
for
the
diverse
abilities
of
the
many
narrow-
spectrum
ones
and
the
versatility
of
the
broad-
spectrum ones—are not the cure-alls, they often
are billed as being.
There are wide
gaps in their ability to master contagious
diseases. Such
important infections as
mumps, measles, common colds,
influenza, and
infectious
hepatitis
still
await
conquest.
All
are
virus
infections
and
despite intense efforts, very
little
progress has been
made in chemotherapy
against
viruses.
Only
small
progress
has
been
achieved
against
fungi.
Many strains of
bacteria and fungi are naturally
resistant to all currently
available
antibiotics
and
other
chemotherapeutic
drugs.
Some
microorganisms
originally
sensitive
to
the
action
of
antibiotics,
especially
staphylococcus, have developed resistant strains.
This acquired
resistance imposes on the
long range value of the drugs a very important
limitation,
which
is
not
adequately
met
by
the
frequent
introduction
of
new antimicrobial agents to combat the
problem.
抗生素的另一面
抗生素已经消除或控制了很多传染
病，实际上每个人都从这种或
那种使用中
受益。
即使没有这样的个人经验，
< br>人们也不
得不孤立地认识到这些
“
奇迹
”
药物的优点，
真实性和推测性
。
美国新闻界，
广播电台和
电视台在报
道有关细菌化学战争成功的真
实故事方面做得很好。
更重要的是
，
制造和
销售抗生素的制药公司的积极的公共关系
活动已经弥补了他们的缺点。
相比之下，这些显着
的药物的不足之
处和潜在的危险是广为人知的。缺乏这样
的知识
可能是不好的，特别是如果它导致
病人迫使他们的医生处方抗生素，当这种
药物是不是真的需要，或导致他们切换到
医生，
直到
他们找到一个谁可以说，
抗生素
-
头脑。
因为抗生素故事的好处是如此
众所周
知，在这里似乎更重要的是要回顾一下当
今随便使用这些
药物可能产生的一些近期
和远期问题。
应该预先说明，
使用抗生素造
成的灾难与所投入的大量药物有关。但是
< br>一般来说很少涉及的潜在危害确实需要一
个明确的说法。
严格来说，
抗生素不是完全
处方药。它们中的一些允许用于鼻腔
喷雾
剂，
锭剂，
锭剂，
霜剂和软膏等非处方产品。
即使这些产品没有坏处，使用它们也没有
任何意义。如果感染的严重程度足以保证
发动化学战争，则需要比任何非处
方产品
所含的抗生素剂量大得多的抗生素。
< br>然而，非处方药产品仅占抗生素总产
量的很小比例。这是给人们麻烦的处方剂
量。
这些药物，
即使考虑到许多窄谱药物的
多样性和广谱药物的多样性，也不是治愈
所有的药物，
他们往往被称为
“
药物
”
。
掌握
传染病的能力差距很大。像腮
腺炎，麻疹，
感冒，流行性感冒和传染性肝炎等重要感
染仍在等
待征服。所有这些都是病毒感染，
尽管付出了巨大的努力，但在化学疗法方
面进展甚微。
真菌只取得小的进展。
许多细
菌和真菌菌株对所有目前可用的抗生素和
其他化学治疗药物都具有天然的
抗性。一
些原本对抗生素作用敏感的微生物，特别
是葡萄球菌，
已经产生了耐药菌株。
这种获
得的耐药
性对药物的远距离价值提出了一
个非常重要的限制，而这种限制并不能通
过频繁引入新的抗菌剂来解决这个问题。
It
has
been
pretty
well
established
that
the
increase
in
strains
of
bacteria resistant to an antibiotic
correlates
directly with the
duration and
extent of use of that
antibiotic in a given location. In one hospital a
survey
showed that,
before erythromycin had been widely
used there, all strains
of
staphylococci taken from patients and personnel
were
sensitive to its
action. When the hospital started
extensive use of erythromycin, however,
resistant staphylococcus
strains
began to
appear.
The development of
bacterial resistance can be minimized by a more
discriminating use of antibiotics, and
the person
taking the drug
can help
here.
When
an
antibiotic
must
be
used,
the
best
way
to
prevent
the
development
of
resistance
is
to
wipe
out
the
infection
as
rapidly
and
thoroughly as possible.
Ideally, this
requires a
bactericidal drug, which
destroys,
rather
than a bacteriostatic drug, which inhibits. And
the drug
must be taken in adequate
dosage for as long as it is
necessary to eradicate
the
infection completely. The doctor, of course, must
choose the drug, but
patients
can
help
by
being
sure
to
take
the
full
course
of
treatment
recommended by the
doctor, even though symptoms seem to disappear
before all the
pills are gone. In rare instances the
emergence of resistance
can be delayed
or reduced by combinations of antibiotics.
Treatment of
tuberculosis with
streptomycin alone results in a high degree of
resistance,
but if para-aminosalicylic
acid or
isoniazid is used
with streptomycin the
possibility that
this complication will arise is greatly
reduced.
In
hospital
treatment
of
severe
infections,
the
sensitivity
of
the
infecting
organism
to
appropriate
antibiotics
is
determined
in
the
laboratory
before treatment is started. This enables the
doctor to select the
most
effective
drug
or
drugs;
it
determines
whether
the
antibiotic
is
bactericidal
or
bacteriostatic
for
the
germs
at
hand; and
it
suggests
the
amount
needed to
destroy the growth of the bacteria completely. In
either
hospital or home, aseptic
measures can help to reduce the
prevalence of
resistant
strains of germs by preventing cross infection and
the resultant
spreading of
organisms.
Every one of the
antibiotics is potentially dangerous for some
people.
Several
serious
reactions
may
result
from
their
use.
One
is
a
severe,
sometimes fatal,
shock-like anaphylactic action, which may strike
people
who have become sensitized
to
penicillin. Anaphylactic
reaction happens
less frequently and is
less severe when the antibiotic is given by mouth.
It
is
most
apt
to
occur
in
people
with
a
history
of
allergy,
or
a
record
of
sensitivity to penicillin. Very small
amounts of
penicillin, even
the traces
which get into the milk of
cows for a few days after they are treated with
the antibiotic for
mastitis, may be sufficient to
sensitize; hence, the strong
campaign
by food and drug officials keeps such milk off
the
market.
To
minimize
the
risk
of
anaphylactic
shock
in
illnesses
where
injections of
penicillin are the preferred treatment,
a
careful doctor will
question the patient carefully about
allergies and previous reactions. In
case
of
doubt
another
antibiotic
will
be
substituted
if
feasible,
or
other
precautionary measures
will be taken before the injection is
given.
Other
untoward
reactions
to
antibiotics
are
gastrointestinal
disorders—such
as
sore
mouth,
cramps,
diarrhea,
or
anal
itch—which
已经确定的是，对抗生素耐药的细菌<
/p>
菌株的增加直接与在给定位置使用抗生素
的持续时间和程度相关。
在一家医院进行
的一项调查显示，在红霉素被广泛使用之
前，所
有从患者和人员中获得的葡萄球菌
菌株对其作用敏感。当医院开始广泛使用
红霉素时，耐药葡萄球菌菌株开始出现。
细菌耐药
性的发展可以通过更加区分
使用抗生素来最小化，服用这种药物的人
可以在这里帮助。
当必须使用抗生素时，
防
止抗药性发展的最好方法是尽可能迅速彻
底地消灭感染。
理想情况下，
这需要一种杀
菌药物，而不是一种抑制抑制药物
的杀菌
药物。
只要有必要彻底根除感染，
必须服用
足够的药物。
当然，
医生必
须选择药物，
但
即使在所有药丸消失之前症状似乎消失，
患者仍然可以通过确保服用医生推荐的整
个治疗过程来提供帮助。在极
少数情况下，
抵抗的出现可以通过抗生素的组合来延迟
或减少。
单独使用链霉素治疗结核病会导
致高度的耐药性，但是如果对氨基水杨酸
或异烟肼与链霉素一起使用，则会出现这
种并发症的可能性大大降低。
在医院治疗严重感染时，在开始治疗
之前，在
实验室中确定感染生物对适当抗
生素的敏感性。这使医生能够选择最有效
的药物或药物
;
它决定了抗生素是否对手边
的细菌具有杀菌或抑菌作用
;
它提示了完全
消灭细菌生长所需的量。
在医院或家中，
无<
/p>
菌措施可以通过预防交叉感染和生物体的
扩散来帮助减少耐药菌株
的流行。
每一种抗生素都对某些人有潜在危
< br>险。他们的使用可能会导致一些严重的反
应。
一种是严重
的，
有时是致命的，
类似休
克的过敏反
应，可能会引起对青霉素敏感
的人。
口服抗生素时，
过敏反应发生频率较
低，
严重程度较轻。
最容易发生在有过敏史
或对青霉素有敏感记录的人群中。非常少
量的青霉素，甚至在用抗生素治疗乳腺炎
之后进入母牛乳中几天的痕迹可
能足以致
敏。
因此，
食品和药物官员的
强力运动使这
种牛奶不在市场上。
为
了尽量减少注射青霉素是首选治疗
的疾病过敏性休克的风险，谨慎的医生会
仔细询问病人有关过敏和以前的反应。如
果有疑问，
如果可行，
另一种抗生素将被替
代，或在注射前采取其他预防措
施。
对抗生素的其他不良反应是使用四环
occur most frequently after
use of the tetracycline group but have
also
been encountered after use of
penicillin
and streptomycin.
These reactions
may result from
suppression by the antibiotic of bacteria normally
found
in the
gastrointestinal tract. With their
competition removed,
antibiotic-
resistant staphylococci or
fungi, which are also normally
present, are free
to
flourish and cause what is called a super-
infection. Such infections can
be
extremely difficult to cure.
A
few
antibiotics
have
such
toxic
effects
that
their
usefulness
is
strictly
limited.
They
include
streptomycin
and
dihydrostreptomycin,
which
sometimes cause deafness, and chloramphenicol,
which may injure
素组后最频繁出现的胃肠疾病
- <
/p>
例如口
疮，
痉挛，
腹泻或肛门瘙痒，
但在使用青霉
素和链霉素后也遇到过。这些
反应可能是
由抗生素抑制胃肠道中正常发现的细菌引
起的。
通过消除竞争，
抗生素抗性葡萄球菌
或真菌
（通常也存在）
可以自由繁殖并引起
所
谓的超感染。这种感染可能极难治愈。
一些抗生素有这样的毒
性作用，它们
的用途是严格限制的。它们包括有时引起
耳聋的链
霉素和二氢链霉素，以及可能伤
the
bone
marrow.
Drugs
with
such
serious
potential
dangers
as
these
should be used only if life is
threatened and nothing else will work. All
the possible
troubles that can result from
antibiotic treatment should not
keep
anyone from using one of these drugs when it is
clearly
indicated.
Nor should they discourage certain
preventive uses of antibiotics which
have proved extremely
valuable.
害骨髓的氯
霉素。只有在生命受到威胁的
情况下才能使用这类具有如此严重潜在危
< br>险的药物，
否则就不能起作用。
在抗生素治
疗中可能产生的所有可能的麻烦都不应该
使任何人在使用这些药物时明确指出
。他
们也不应该阻止某些已被证明非常有价值
的抗生素的预防性
用途。
Discovery of Insulin, and the Making of
a
Medical Miracle
Background
Insulin is a hormone that regulates the
amount of glucose (sugar)
in the blood
and is required for the body to function normally.
Insulin
is
produced
by
β-cells
in
the
pancreas,
also
called
the
islets
of
Langerhans. These cells continuously
release a small amount of insulin
into
the body, but release surges of the hormone in
response to a rise
in the blood glucose
level.
Certain cells in the
body change the food ingested into energy, or
blood glucose, that cells can use.
Every time a person eats, the blood
glucose rises. Raised blood glucose
triggers the cells in the islets of
Langerhans to release the necessary
amount of insulin. Insulin allows
the
blood glucose to be transported from the blood
into the cells. Cells
have an outer
wall, called a membrane, which controls what
enters and
exits the cell. Researchers
do not yet know exactly how insulin works,
but they do know insulin binds to
receptors on the cell membrane. This
activates a set of transport molecules
so that glucose and proteins can
enter
the cell. The cells can then use the glucose as
energy to carry out
its functions. Once
transported into the cell, the blood glucose level
is
returned to normal within hours.
Without insulin, the blood
glucose builds up in the blood and the
cells are starved of their energy
source. Some of the symptoms that
may
occur
include
fatigue,
constant
infections,
blurred
eye
sight,
numbness, tingling in the hands or
legs, increased thirst, and slowed
healing of bruises or cuts. The cells
will begin to use fat, the energy
source stored for emergencies. When
this lasts for too long a time the
body
produces ketones, chemicals produced by the liver.
Ketones can
poison
and
kill
cells
if
they
build
up
in
the
body
over
an
extended
period of time. This can lead to
serious illness and coma.
People who do not produce the necessary
amount of insulin have
diabetes. There
are
two
general
types
of
diabetes. The
most
severe
type, known as Type
or juvenile-onset diabetes, is when the body does
not
produce
any
insulin,
Type
I
diabetics
usually
inject
themselves
with different types of insulin three
to four times daily. Dosage is taken
based
on
the
person's
blood
glucose
reading,
taken
from
a
glucose
meter.
Type
n
diabetics
produce
some
insulin,
but
it
is
either
not
enough or their cells do not respond
normally to insulin. This usually
occurs in obese or middle aged and
older people. Type II diabetics do
not
necessarily need to take insulin, but they may
inject insulin once
or twice a
day.
胰岛素的发现和医学奇迹的建立
背景
胰岛素是一种调节血液中葡萄糖
（糖）
含
量的激素，
< br>是人体正常功能所必需的。
胰岛素
由胰腺中的
β
细胞产生，也称为朗格罕氏胰
岛。这些细胞不断
释放少量的胰岛素进入人
体，但随着血糖水平的升高而释放激素的激
增。
体内的某些细胞会将摄入的食物转化为
细胞可以利用的能量或血糖。
每人一吃，
血糖
就会升高。
升高的血糖引发朗格汉斯胰岛中的
细胞释放必要量的胰岛素。
胰岛素允许血液从
血液运输到细胞。
细胞有一个外壁，称为膜，
它控制着什么进入和离开细胞。
研究
人员尚不
清楚胰岛素是如何工作的，
但他们知道胰岛素
与细胞膜上的受体结合。
这激活了一组转运分
子
，
使葡萄糖和蛋白质可以进入细胞。
然后细
胞可以使用葡萄糖作为能量来执行其功能。
一
旦运送到细胞
中，
血糖水平在数小时内恢复正
常。
如果没有胰岛素，
血液中的血糖会积聚在
血液中，
细胞就会缺乏能量来源。
可能发生的
一些症状包括疲劳，感染持续，视力模糊，手
脚麻木，
手脚刺痛，
口渴增加，
伤口愈合减慢。
细胞将开始使用脂肪，紧急情况下储存的能
源。当这种持续时间太长时，身体会产生酮，
肝脏产生的化学物质。
如果酮在体内长时间累
< br>积，
酮可以毒杀细胞。
这可能导致严重的疾病
和昏迷。
不产生必需量的胰岛素的人患有糖尿病
。
有两种一般类型的糖尿病。
最严重的类型，
< br>即
类型或青少年型糖尿病，
是当身体不产生任何
胰岛素时，
I
型糖尿病患者通常每天注射不同<
/p>
类型的胰岛素三至四次。
根据从葡萄糖计取得
的人的血糖读数来服用剂量。
n
型糖尿病患者
会产生一些胰岛素，
但这或者是不够的，
或者
他们的细胞对胰岛素没有正常的反应。
这通
常
发生在肥胖或中年人和老年人。
I
I
型糖尿病
患者不一定需要服用胰岛素，
但可以每天注射
一次或两次胰岛素。
胰岛素几乎没有被发现
在发现胰岛素
之前，
糖尿病是一种可怕的
疾病，最可能导致死亡。病人浪费了
，变得虚
弱，
在不可避免的死亡之前难以形容。
他们渴
望饥渴，
但饥饿只是让事情变得更糟，
继续减
肥。医生知道，糖会加重糖尿病患者的病情，
How Insulin Almost Wasn't Discovered
Before the discovery of insulin,
diabetes was a feared disease that
most
certainly
led
to
death.
Patients
wasted
away,
grew
weak,
and
suffered
indescribably
before
their
inevitable
death.
They
had
insatiable
thirst
and
hunger,
but
trying
to
satisfy
their
hunger
only
made things worse, and they continued
to lose weight. Doctors knew
that sugar
worsened the condition of diabetic patients and
that the most
effective treatment was
to put the patients on very strict diets where
sugar intake was kept to a minimum. At
best, this treatment could buy
patients
a few extra years, but it never saved them. In
some cases, the
harsh diets even caused
patients to die of starvation.
During the nineteenth century,
observations of patients who died
of
diabetes often showed that the pancreas was
damaged. In 1869, a
German
medical
student,
Paul
Langerhans,
found
that
within
the
pancreatic tissue that
produces digestive juices there were clusters of
cells
whose
function
was
unknown.
Some
of
these
cells
were
eventually shown to be the insulin-
producing beta cells. Later, in honor
of the person who discovered them, the
cell clusters were named the
islets of
Langerhans.
In
1889
in
Germany,
physiologist
Oskar
Minkowski
and
physician
Joseph
von
Mering,
showed
that
if
the
pancreas
was
removed from a dog, the animal got
diabetes. But if the duct through
which
the pancreatic juices flow to the intestine was
ligated-surgically
tied
off
so
the
juices
couldn't
reach
the
intestine-the
dog
developed
minor
digestive
problems
but
no
diabetes.
So
it
seemed
that
the
pancreas must have at least two
functions:
?
To
produce digestive juices
?
To produce a substance that
regulates the sugar glucose.
This hypothetical internal secretion
was the key. If a substance
could
actually be isolated, the mystery of diabetes
would be solved.
Progress, however, was
slow.
In 1920, an unknown
Canadian surgeon named Frederick Banting
approached
Professor
John
Macleod,
the
head
of
the
University
of
Toronto's
physiology
department,
with
an
idea
about
finding
that
secret.
He
theorized
that
the
pancreatic
digestive
juices
could
be
harmful
to
the
secretion
of
the
Pancreas
produced
by
the
islets
of
Langerhans. He therefore wanted to
ligate the pancreatic ducts in order
to
stop the flow of nourishment to the pancreas. This
would cause the
pancreas to degenerate,
making it shrink and lose its ability to secrete
the
digestive
juices.
The
cells
thought
to
produce
an
antidiabetic
secretion
could
then
be
extracted
from
the
pancreas
without
being
harmed.
Unfortunately,
Macleod,
a
leading
figure
in
the
study
of
diabetes
in
Canada,
didn't
think
much
of
Banting's
theories
and
rebuffed
his
suggestion. Despite
this,
Banting
managed
to
convince
Macleod
that
his
idea
was
worth
trying.
Macleod
gave
Banting
a
laboratory with a minimum of equipment
and ten dogs. Banting also
got an
assistant, a medical student by the name of
Charles Best. The
experiment was set to
start in the summer of 1921.
Banting
and
Best
began
their
experiments
by
removing
the
pancreas from a dog. This resulted in
the following:
?
It's blood sugar rose.
最有效的治疗方法是将病人的糖摄入量控制
在非常严格的水平。
充其量，
这种治疗可以多
买几年的病人，
但从来没有挽救过。
在某些情
况下，严酷的饮食
甚至导致病人死于饥饿。
在十九世纪期间，
< br>死于糖尿病的病人的观
察结果常常表明胰脏已经受损。
1869
年，一
位德国医学学生
Paul Langerhans
发现，
在产
生
消化液的胰腺组织内，有功能未知的细胞簇。
其中一些细胞最
终被证明是产生胰岛素的
β
细胞。后来，为了纪念发现他们的人
，细胞群
被命名为朗格汉斯岛。
18
89
年在德国，生理学家奥斯卡
·
闵可
夫
斯基（
Oskar Minkowski
）和医师约瑟夫
·
冯
·
梅
林（
Joseph von Mering
）发现，如果将胰脏从
狗身上取下，动物就会患上糖尿病。但是，如
果将胰液流入肠道的导管结扎在外科手术中，
使得汁液不能到达
肠道，
那么狗就会产生轻微
的消化问题，
但不会产生糖尿病。
所以胰腺似
乎至少有两个功能：
?
产生消化液
?
生产调节糖分的物质。
这个假设的内分泌是关键。
如果一个物质
实际上可
以孤立，
糖尿病的奥秘将被解决。
但
进
展缓慢。
1920
年
，
一
位
名
叫
弗
雷
德
里
克
·
班
廷<
/p>
（
Frederick Banting
）
的未知加拿大外科医生向
多伦多大学生理学系主任约翰
·
麦克劳德
（
Joh
n
Macleod
）教授提供了一个关于如何找到这个
秘密的想法。
他推论胰腺消化液可能对朗格汉
斯胰岛产生的胰腺分泌有害。
因此，
他想结扎
< br>胰管，
以阻止营养物流向胰腺。
这会导致胰腺
退化，使其萎缩，失去分泌消化液的能力。认
为产生抗糖尿病分泌物的细胞
然后可以从胰
腺中提取而不受伤害。
不幸的是，
加拿大糖尿
病研究领域的领军人物麦克劳德
（
Macleod
）
对
班
廷的理论并没有太多的想法，
并且拒绝了他
的建议。
尽管如此，
万津设法说服了麦克劳德，
他的想法值
得尝试。
麦克劳德给班廷一个实验
室，
配备了最少的设备和十只狗。
班廷还找到
了一位名叫查尔斯
·
贝斯特的医学助理。实验
定于
1921
年夏天开始。
万津和最好的开始他们的实验，
从狗取出
胰腺。这导致了以下结
果：
?
血糖升高
?
口渴，多喝水，多喝水。
?
变得越来越弱对另一只狗进行试验
，万
津和贝佳手术结扎胰腺，停止营养的流
动，使胰腺退化。过
了一段时间，他们
?
It became thirsty drank lots of water,
and urinated more often.
?
It
became
weaker
and
weaker
Experimenting
on
another
dog,
Banting
and
Best
surgically
ligated
the
pancreas,
stopping
the
flow
of
nourishment,
so
that
the
pancreas
degenerated. After
a
while, they removed the
pancreas, sliced it up and froze the pieces
in a mixture of water and salts. When
the pieces were half frozen,
they
were
ground
up
and
filtered.
The
isolated
substance
was
named
“isletin”.
The extract was
injected into the diabetic dog. Its blood glucose
level
dropped,
and
it
seemed
healthier
and
stronger.
By
giving
the
diabetic dog a few injections a day,
Banting and Best could keep it
healthy
and free of symptoms. Banting and Best showed
their result to
Macleod, who was
impressed but he wanted more tests to prove that
their
pancreatic
extract
really
worked.
For
the
increased
testing,
Banting and Best realized that they
required a larger supply of organs
than
their dogs could provide, and they starred using
pancreases from
cattle. with this new
source, they managed to produce enough extract
to
keep
several
diabetic
dogs
alive.
The
new
results
convinced
Macleod that they were onto something
big. He gave them more funds
and moved
them to a better laboratory with proper working
conditions.
He also suggested that they
should call their extract
work
proceeded
rapidly.
In
late1921,
a
third
person
biochemist
Bertram Collip,
joined the team. Collip was given the task of
trying
topuri4
the
insulin
so
that
it
would
be
clean
enough
for
testing
on
humans. During the intensified testing,
the team also realized that the
process
of
shrinking
the
pancreases
had
been
unnecessary.
Using
whole fresh pancreases
from adult animals worked just as well.
In 1922 the insulin was tested on
Leonard Thompson, a 14-year-
old
diabetes patient who lay dying at the Toronto
General Hospital. He
was given an
insulin injection. At first he suffered a severe,
allergic
reaction and further
injections were cancelled. The scientists worked
hard on improving/ the extract and then
a second dose of injections
were
administered
on Thompson.
The
results
were
spectacular. The
scientists
went to the other wards with diabetic children,
most of them
comatose and dying from
diabetic keto-acidosis. They reacted just as
positively as Leonard to the insulin
extract.
Banting and Macleod
were awarded the Nobel Prize in 1923 for
the practical extraction of insulin.
They were incensed that the other
members of their team were not
included, and they immediately shared
their prize money with Best and Collip.
They sold the original patent
to the
University of Toronto for one half dollar. They
were not looking
for
fame
or
fortune;
they
wanted
to
keep
sick
children
from
dying.
They
did eventually benefit financially, but that was
the last thing on
their
minds.
Very soon after the
discovery of insulin, the medical firm Eli Lilly
started large-scale production of the
extract. As early as in 1923, the
firm
was
producing
enough
insulin
to
supply
the
entire
North
American continent.
Although insulin doesn't cure diabetes, it's one
of
将胰脏切除，将其切片并冻结在水和盐
的混合物中。当冰
块半冻时，将其磨碎
并过滤。分离的物质被命名为“通
报”。<
/p>
将提取物注射到糖尿病狗中。
其血糖水
平
下降，
似乎更健康和更强。
通过给糖
尿病狗每
天注射几次，
Banting
和
Best
可以保持健康和
没有症状。
Banting
和
< br>Best
向麦克劳德展示了
他们的成果，
他对此印象深刻，
但他想要进行
更多的测试来证明他们
的胰脏提取物确实有
效。为了增加测试，
Banting
和
Best
认识到他
们需要比他们的狗能够提供更多的器官供应，
并且他们使用来自牛的胰脏来主演。
有了这个
新的来源，
他们设法产生足够的提取
物，
让几
只糖尿病的狗保持活着。
新的
结果使麦克劳德
相信他们正在做一些大事。
他给了他们更多的<
/p>
资金，
把他们搬到了一个有适当工作条件的更
好的实验室。
他还建议，
他们应该叫他们的提
取物
“
胰岛素
”
。
现在，
工作进展迅速。
在
1921
年底，第三人称生物化学家
Bertram
Collip
加
入了
队伍。
Collip
被赋予尝试
topuri4
胰岛素
的任务，
以便它足够干净，
可以在人体上进行
测试。
在加强检测过程中，
团队也意识到缩小
胰腺的
过程是不必要的。
使用来自成年动物的
全新鲜的胰腺也同样如此
。
1922
年，在
< br>14
岁的多伦多综合医院死亡
的
糖
尿
病
患
者<
/p>
伦
纳
德
·
汤
普
森
（
Leonard
Thompson
）
身上测试了胰岛素。
他被给了胰岛
素注射。起初，
他遭受了严重的过敏反应，取
消了进一步的注射。科学家努力改善
/
提取物，
然后在汤普森进行第二次注射。结果是壮观
的。科学家去了另一个病房与糖尿病的孩子，
他们大多是昏迷和死于糖
尿病酮酸中毒。
他们
的反应和
Leon
ard
一样积极。
万津和麦克劳德在
1923
年被授予诺贝尔
奖，用于实际
提取胰岛素。他们被激怒，其他
队员不包括在内，
他们立即用<
/p>
Best
和
Collip
分
享他们的奖金。
他们把原来的专利卖给了多伦
多大学半美元。
他们不是为了名利，
他们想让
生病的孩子免于死亡。他们最终在经济上受
益，但这是他们心中
的最后一件事。
在发现胰岛素后不久，医药公司
Eli
Lilly
就开始大规模生产提取物。早在
1923
年，该
公司就生产出足够的胰岛素供应整个北美大
陆。
虽然胰岛素不能治愈糖尿病，
但这是医学
界最大的发现之一。
一旦到来，
就像是一个奇
迹。
患有严重糖尿病，
只剩下几天生活的人得<
/p>
the
biggest
discoveries
in
medicine.
When
it
came,
it
was
like
a
救了。
只要不断得到胰岛素，
他们就能过上几
miracle
. People with severe diabetes and only days left
to live were
乎正常的生活。
saved. And as long as they kept getting
their insulin, they could live an
使用人胰岛素
almost
normal life.
1982
年，礼来公司生产了一种人胰岛素
Working with human
insulin
（
Humulin?
）
，
成为首个获得批准的基因工程
In
1982,
the
Eli
Lilly
Corporation
produced
a
human
insulin <
/p>
药物产品。
这一重要成就是
20
世纪
50
年代由
(Hu
mulin?)
that
became
the
first
approved
genetically
engineered
沃森和克里克对
DNA
进行的经典结构研究以
pharmaceutical
product. This important achievement was the result
of
及由桑格公司提供的胰岛素开始的一个广泛
a vast
network of basic and applied scientific advances
that began in
的基础和应用科学进展网络的结果。
研究人员
the 1950s with the classic
structural studies on DNA by Watson and
Crick
and
on
insulin
by
Sanger.'
Without
needing
to
depend
on
animals, researchers
could produce genetically engineered insulin in
unlimited
supplies.
It
also
did
not
contain
any
of
the
animal
contaminants. Using human insulin also
took away any concerns about
transferring
any
potential
animal
diseases
into
the
insulin.
While
companies
still
sell
a
small
amount
of
insulin
produced
from
animals—mostly
porcine—from
the
1980s
onwards,
insulin
users
increasingly
moved
to
a
form
of
human
insulin
created
through
recombinant DNA
technology.
Insulin
is
a
protein
consisting
of
two
separate
chains
of
amino
acids,
an A above a B chain, that are held together with
disulfide bonds.
The insulin A chain
consists of 21 amino acids and the B chain has 30.
Before becoming an active insulin
protein, insulin is first produced as
preproinsulin. This is one single long
protein chain with the A and B
chains
not
yet
separated,
a
section
in
the
middle
linking
the
chains
together and a signal sequence at one
end telling the protein when to
start
secreting outside the cell. After preproinsulin,
the chain evolves
into proinsulin,
still a single chain but without the signaling
sequence.
Then comes the active protein
insulin, the protein without the section
linking the A and B chains. At each
step, the protein needs specific
enzymes to produce the next form of
insulin.
Lilly
has
prepared
human
insulin
by
two
different
means'
initially,
by
a
chain
combination
procedure
and,
since
1986,
by
transforming human
proinsulin into human insulin. In the first
method,
the two insulin chains are
produced separately. Manufacturers need the
two mini-genes: one that produces the A
chain and one for the B chain.
Since
the exact DNA sequence of each chain is known,
they synthesize
each
mini-
gene's
DNA
and
insert
them
into
plasmids.
The
recombinant,
newly
formed,
plasmids
are
then
transformed
into
bacterial cells. During a fermentation
process, the millions of bacteria
harboring the recombinant plasmid
replicate roughly every 20 minutes
through
cell
division,
and
each
expresses
the
insulin
gene.
After
multiplying,
the
cells
are
taken
out
of
the
fermentation
tanks
and
broken
open
to
extract
the
protein
chains. The
two
chains
are
then
mixed together and joined by disulfide
bonds through the reduction-
reoxidation
reaction.
Although
the
chain
combination
procedure
worked quite well, the proinsulin
approach required fewer processing
不需要依
赖动物，
就可以生产出无限制供应的
基因工程胰岛素。
它也没有包含任何动物污染
物。
使用人体胰岛素
也消除了将任何潜在动物
疾病转移到胰岛素中的担忧。尽管从
2
0
世纪
80
年代开始，
公司仍然出售少量由动物产生的
胰岛素（主要是猪），但是胰岛素使用者越来<
/p>
越多地转向通过重组
DNA
技术形成的人
胰岛
素形式。
胰岛素是一种蛋白质，
由两条独立的氨基
酸链组成，一条
B<
/p>
链以上的
A
链与二硫键结
合在一起。胰岛素
A
链由
21
个氨基酸组成，
B
链有
30
个。
在成为活性胰岛素蛋白质之前，
胰岛素首先作为前胰岛素原产生。
这是一个单
链长的
蛋白质链，
A
链和
B
< br>链还没有分开，
中
间的一段链接在一起，
信号序列的一端告诉蛋
白质何时开始在细胞外分泌。前胰岛素原后，
链发展成胰岛素原，
仍然是单链，
但没有信号
序列。然后是活性蛋白质胰岛素，不含连接
A
和
B
链的部分的蛋白质。
在每个步骤
中，
蛋白
质都需要特定的酶来产生下一种形式的胰岛
素。
礼来公司通过两种不同的方式来制备人
胰岛素
-
最初
是通过链式结合的方法，自
1986
年以来，
< br>通过将人胰岛素原转化成人胰岛
素，
第一种方法是分别生
产两种胰岛素链，
基
因：一个产生
A<
/p>
链和一个
B
链，由于每条链
的确切的
DNA
序列是已知的，他们合成每个
小基因的
DNA
并将它们插入到质粒中，然后
转化新形成的重组质粒在发酵过程中，
携带重
< br>组质粒的数百万个细菌通过细胞分裂大约每
隔
20
分钟复制一次，每个细胞表达胰岛素基
因
;
倍增后，将细胞从发酵罐中取出，打开提
取蛋白质链，
然后将两条链混合在一起，
通过
还原
-
再氧化反应通过二硫键连接，尽管链
组合过程起作用胰岛素原方法需要较少的处
理步骤，因此在
1986
年取代了链式方法。将
编码胰岛素原的序
列插入到非致病性大肠杆
菌细菌中。
细菌经过发酵过程，
再生产胰岛素
-
-
-
-
-
-
-
-
-
上一篇：有关“一个人”用英语口语怎么说
下一篇：雅思作文背诵范文(很全必背)