Tuesday, 2 April 2013

Link to key in result of experiment

Link to key in results

Please construct a table that shows the temperature, rate of change of pH and the average change of pH for each temperature below the table on page 36.

Draw the graph after that and submit on Thurs.

Wednesday, 27 March 2013

Protein's 3D shape

This is how proteins folds. At temperatures beyond optimum temperature of the enzyme, the weak hydrogen bonds that hold the molecules in its 3-dimensional shape breaks.

Sunday, 13 January 2013

What is the definition (legally and medically) of death?

Legal Definitions of Death:

- Uniform Determination of Death Act (America)
An individual who has sustained either (1) irreversible cessation of circulatory and respiratory functions, or (2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead. A determination of death must be made in accordance with accepted medical standards. 

-Legal definition of death in Australia
The legal definition of death in the States and Territories of Australia, with the exception of
Western Australia, is that a person is dead when there is irreversible cessation of circulation of blood in the body of the person, or irreversible cessation of all function of the brain of the person. In Western Australia organs and tissues may be removed for the purposes of transplantation if two medical practitioners certify that irreversible cessation of all function of the brain has occurred.

Medical Definition of Death:

-UK Guidance on Confirmation of Death
Proceed without unnecessary and distressing delay. Death may be obvious with clear signs pathognomonic of death (hypostasis, rigor mortis). If not obvious death should be identified by 'the simultaneous and irreversible onset of apnoea and unconsciousness in the absence of the circulation'. The new guidance in addition requires that:
Full and extensive attempts at reversal of any contributing cause to the cardiorespiratory arrest have been made (for example body temperature, endocrine, metabolic and biochemical abnormalities more relevant in hospital).
One of the following is fulfilled:
The individual meets the criteria for not attempting cardiopulmonary resuscitation
Attempts at cardiopulmonary resuscitation have failed
Treatment aimed at sustaining life has been withdrawn because it has been decided to be of no further benefit to the patient and not in his/her best interest to continue and/or is in respect of the patient’s wishes in an advanced directive
The individual should be observed by the person responsible for confirming death for a minimum of five minutes to establish that irreversible cardiorespiratory arrest has occurred. In primary care the absence of mechanical cardiac function is normally confirmed using a combination of the following:
Absence of a central pulse on palpation
Absence of heart sounds on auscultation
In hospital this can be supplemented by one or more of the following:
Asystole on a continuous ECG display
Absence of pulsatile flow using direct intra-arterial pressure monitoring
Absence of contractile activity using echocardiography
Any spontaneous return of cardiac or respiratory activity during this period of observation should prompt a further five minutes observation from the next point of cardiorespiratory arrest
After five minutes of continued cardiorespiratory arrest the absence of the pupillary responses to light, of the corneal reflexes, and of any motor response to supra-orbital pressure should be confirmed
The time of death is recorded as the time at which these criteria are fulfilled.

How has the definition of death changed through the years and how does it vary across cultures?

How has the definition of death changed through the years and how does it vary across cultures?

Definition of death changed through the years

Death is a concept. It is formed through ideas, beliefs and attitudes of people. For example, a person that would be unconscious to a group of scientists would be considered dead by a group of people living Vanatinai, a small island near Papua New Guinea. It varies from culture to culture and to many could be either the absence of life or the simple fact that one is in a coma. Of course, the idea of death has changed throughout the years as humans have become more intelligent, changed their beliefs and their attitude towards Science.

Back in the past, the people of then were far from as knowledgeable or resourceful or even as flexible in their thinking and beliefs when compared to the people of today. If one was in a coma, they would probably be treated as dead but if they were still breathing then they would try their best to get the man in coma to be resuscitated. Although medical treatments were not properly worked out then and technology was not as advanced, if a man's heart was pumping or if he was breathing - he's alive. If not - he's dead. Just because one was Brain-dead(although a term as such was unlikely to exist back in the day) does not mean he is dead. Back in the past, all they needed to prove you were still alive, was the fact that you were still breathing.

Today, a person is considered dead if they are legally dead. This could mean that one is medically dead(his body being unable to function at all) or just Brain-dead, both of which would mean that one is dead - or at least thought to be so today. While there are many ethical issues concerning being Brain-dead to be legally dead, it is generally the consensus today that the policy of being Brain-dead would be equivalent to being dead.

The definition of being dead today however has a big flaw. The definition of death could vary from profession to profession in the field of Sciences. For example, being Brain-dead to a cardiologist would not mean that a person is dead as to him a person being dead would most probably be one's heart stopping and being unable to be restarted. However, a neurologist would probably have a different opinion on the matter. Let's go back to the past again to see how the method of defining whether one was dead was found. Back then in order to define whether a person is dead, the people would most likely use a set of criteria to define whether one is dead. Whether a key central organ of a human was working was probably included in the criteria, and as for that, they might have used the heart or the lungs. Today, we use the brain. Our argument being that it makes our decisions for us, controls our action and is somewhat the core of everything we ever do and without it we would not matter. The big issue of using this criteria was that there always seemed to be an exception. Take for instance, the method used today, whether one is Brain-dead or not, the major flaw being that the heart might still be beating.

All in all, the definition of death has not changed much throughout the ages. It is all basically whether a major organ has stopped working and whether it could be restarted. However, there is no solid way to determine and define death. A way to define death would be to say that is the absence of life, but then we would have to define life, which is almost impossible. In conclusion, there is no definitive standard for being dead or which organ stopping it's functions would be responsible for a person being called 'dead'(for instance a heart may not be beating but to a cell biologist he might want to see all cells dead). 

Varying across cultures:
The center of many traditions, organizations or customs have different features but one very glaring feature of every culture around the world is the topic of death. Some of which revolves around care of the dead, the afterlife and the disposal of the bodies after certain steps/rituals have been carried out.
   Disposal of human corpses in general, begin with the last offices() before significant time has passed, and ritualistic ceremonies often occur, most commonly interment or cremation. Though this is not a unified practice, For instance, in Tibet, the body is given a sky burial and left on a mountain top. Mummification or embalming is also prevalent in some cultures, to reduce the rate of decay. Legal aspects of death are also part of many cultures, particularly the settlement of the deceased estate and the issues of inheritance and in some countries, inheritance taxation. Another proper preparation for death and techniques and ceremonies for producing the ability to transfer one's spiritual attainments into another body (reincarnation) are subjects of detailed study in Tibet. An example of modern day death disposal is in Brazil. In Brazil, a human death is counted officially when it is registered by existing family members at a cartório, a government-authorized registry. Before being able to file for an official death, the deceased must have been registered for an official birth at the cartório. Though the Public Registry Law guarantees all Brazilian citizens the right to register deaths, regardless of their financial circumstances, of their family members though the government has not taken away the hidden fees for filing a death which leads to impoverished families having their own, unofficial, local and cultural burial.
   In the modern world, death is usually reserved as the capital punishment where, in most jurisdictions, the death penalty is reserved for premeditated murder, espionage, treason, or as part of military justice. In many countries, drug trafficking and sexual crimes such as adultery also carry the death penalty as do religious crimes such as apostasy(the abandonment of belief). For example, human trafficking and serious cases of corruption in China are also punished by the death penalty. Where as, in militaries around the world, courts-martial have imposed death sentences for offenses such as cowardice, desertion, insubordination, and mutiny. Death in warfare and in suicide attack also have cultural links, and ideas like mutiny are punishable by death, grieving relatives of dead soldiers and death notification are also embedded in many cultures. 
   The topic of death also includes the topic of suicide, suicide in general, and particularly euthanasia, are also points of cultural debate. Both acts are understood very differently in different cultures. In Japan, for example, ending a life with honor by seppuku was considered a desirable death, whereas according to traditional Christian and Islamic cultures, suicide is viewed as a sin. Death is also personified in many cultures, with symbolic representations as the Grim Reaper, Azrael and Father Time.
   All in all, the topic of death and witnessing it is a difficult issue with most cultures. Western societies may like to treat the dead with the utmost material respect, with an official embalmer and associated rites. While eastern societies (like Indian) may be more open to accepting it with a funeral procession of the dead body ending in an open air burning-to-ashes.


What are some criteria the medical community uses to determine if one is “brain dead”?

A. Prerequisites.  Brain death is the absence of clinical brain function when the proximate cause is known and
demonstrably irreversible.
1. Clinical or neuroimaging evidence of an acute CNS catastrophe that is compatible with the clinical
diagnosis of brain death
2. Exclusion of complicating medical conditions that may confound clinical assessment (no severe electrolyte, acid-base, or endocrine disturbance)
3. No drug intoxication or poisoning
4. Core temperature ≥ 32° C (90°F)

B. The three cardinal findings in brain death are coma or unresponsiveness, absence of brainstem reflexes, and
1. Coma or unresponsiveness--no cerebral motor response to pain in all extremities (nail-bed pressure andsupraorbital pressure)
2. Absence of brainstem reflexes
a) Pupils
i. No response to bright light
ii. Size: midposition (4 mm) to dilated (9 mm)
b) Ocular movement
i. No oculocephalic reflex (testing only when no fracture or instability of the cervical spine is apparent)
ii. No deviation of the eyes to irrigation in each ear with 50 ml of cold water (allow 1 minute after injection and at least 5 minutes between testing on each side) Brain Death
c) Facial sensation and facial motor response
i. No corneal reflex to touch with a throat swab
ii. No jaw reflex
iii. No grimacing to deep pressure on nail bed, supraorbital ridge, or temporomandibular joint
d) Pharyngeal and tracheal reflexes
i. No response after stimulation of the posterior pharynx with tongue blade
ii. No cough response to bronchial suctioning

3. Apnea--testing performed as follows:
a) Prerequisites
i. Core temperature ≥ 36.5°C or 97°F
ii. Systolic blood pressure ≥ 90 mm Hg
iii. Euvolemia.  Option: positive fluid balance in the previous 6 hours
iv. Normal PCO2. Option: arterial PCO2 ≥ 40 mm Hg
v. Normal PO2 Option: preoxygenation to obtain arterial PO2 ≥ 200 mm Hg
b) Connect a pulse oximeter and disconnect the ventilator.
c) Deliver 100% O2, 6 l/min, into the trachea.  Option: place a cannula at the level of the carina.
d) Look closely for respiratory movements (abdominal or chest excursions that produce adequate tidal volumes).
e) Measure arterial PO2, PCO2, and pH after approximately 8 minutes and reconnect the ventilator.
f) If respiratory movements are absent and arterial PCO2 is ≥ 60 mm Hg (option: 20 mm Hg increase
in PCO2 over a baseline normal PCO2), the apnea test result is positive (ie, it supports the diagnosis of brain death).
g) If respiratory movements are observed, the apnea test result is negative (ie, it does not support the clinical diagnosis of brain death), and the test should be repeated.
h) Connect the ventilator if, during testing, the systolic blood pressure becomes ≤ 90 mm Hg or the pulse oximeter indicates significant oxygen desaturation and cardiac arrhythmias are present; immediately draw an arterial blood sample and analyze arterial blood gas. If PCO2 is ≥ 60 mm Hg or PCO2 increase is ≥ 20 mm Hg over baseline normal PCO2, the apnea test result is positive (it supports the clinical diagnosis of brain death); if PCO2 is < 60 mm Hg or PCO2 increase is < 20 mm Hg over baseline normal PCO2, the result is indeterminate, and an additional confirmatory test
can be considered.


Describe some difference between “persistent vegetative state” and “brain death”

Persistent vegetative state: A wakeful unconscious state that lasts longer than a few weeks.
Brain death: Irreversible brain damage causing the of independent respiration, regarded as indicative of death.

Persistent vegetative state
  • Has damage to areas of the brain responsible for consciousness, self-awareness, personality, head injury and oxygen deprivation.
  • If coma lasts for more than a month or so, it is known as a persistent vegetative state.
  • Brain loses higher functions, but can still maintain involuntary functions such as breathing and swallowing, heart rate and blood pressure. 
  • The patient would require artificial feeding.
  • Given adequate treatment the patient can survive for years and may recover towards the minimally conscious state or can gain complete recovery.
Brain death
  • Not in coma. 
  • The irreversible loss of brain function. 
  • The patient is unconscious but still considered legally alive.
  • They often still have a heartbeat, they breathe with the help of a ventilator.

What are some of the ethical implications of these definitions of death? Provide some real-life examples

 Definitions of death :

According to surgeons, if the victim shows a slight reaction to anything, he will not be considered brain dead.
Ventilators are used to keep brain dead patients alive while decisions are made on their part.

Procedure of donation of organs
Dispute occurred in England concerning the reaction of the patients during organ removal while on ventilator.
Anesthetic (painkillers) are used during the operation, HOWEVER if none is used and patients are able to react to the pain, it might be too late as the blood pressure and heartbeat increases dramatically with only one cut.
If certified brain dead before the organ removal, the patient would not be dosed with anesthetic which is considered euthanasia.

Example 1 :
Cadaveric organ donation from brain-dead patients is the most common and preferred source of organs for transplantation.

Marion, 45, an administrative assistant, suddenly became unresponsive at work. She was placed on mechanical ventilation, and transferred to the ICU. Marion was classified as a brain-dead donor even though her heart continued to beat. Mechanical ventilation was continued to ensure heart and lung perfusion and to preserve organ integrity for possible transplant.

Knowing that she is still alive, her families could not do anything but stand by and watch. When asked for consent for organ donations, Bob, Marion’s husband had to make a decision for his wife. If the patient has not legally consented for their organs to be donated, the choices are made by family according to their own values goals and priority.

In the end, Bob donated Marion's organs and tissues to the GOL.
Many arguments have been brought up since regarding whether patients diagnosed with ‘brain death’ should have a choice to donate or not to donate their organs when they aren’t legally certified as being dead.

Example 2:
“A 58-year-old British man suffering from so-called locked-in syndrome died Wednesday, six days after a panel of High Court judges rejected his request for help in ending his life.” http://www.bbc.co.uk/news/health-19249680

After having a stroke, Mr. Nicklinson, developed locked-in syndrome, an incurable condition in which a patient loses all motor functions but remains awake and aware. He had spent the last seven years paralyzed from neck down.

He argued and would like to seek permission from the court to have a doctor administer the necessary dose without fear of prosecution. Under British law, anybody, including a doctor, who knowingly helps a terminally ill person to die faces possible criminal prosecution.

Mr. Nicklinson said, “It cannot be acceptable in 21st-century Britain that I am denied the right to take my own life just because I am physically handicapped.” He added, “It is astonishing that in 1969 we could put a man on the moon, yet in 2012 we still cannot devise adequate rules for government-assisted dying.”

In Europe, only Belgium, Luxembourg and the Netherlands allow Euthanasia. The British law against assisted suicide was mitigated in 2010 with a statement by the Crown Prosecution Service, that set out the detailed circumstances that would be taken into account in reaching a decision on whether to press charges.

Monday, 7 January 2013

Human Chimerism

Since we were talking about this today, I managed to find this video online which is the case study one of you brought up. I was pleasantly surprised to know that someone actually read about this before. 

So here it is, "The Human Chimera". :)


Dear Biologists of 302,

A very warm welcome back to school once again and I hope I managed to ignite a teeny-weeny bit of enthusiasm in you today about Biology. 

This blog will be an avenue where we will post our class activities as well as any additional materials to aid you in your understanding of the things covered in class.

First announcement I'd like to make is that there'll be a diagnostic test this week Thursday. The topics covered are

1) Classification of Living Organisms
2) Cells
3) Nutrition in Humans
4) Transport in Humans
5) Ecology

Thank you and I wish us a very fruitful year together.