limbic system

The term ‘limbic system’ (from Latin limbus: edge) was first used by MacLean in 1952 to describe a set of structurally and functionally related structures of the brain bordering the midline, inner surface of each cerebral hemisphere. These structures were considered to be evolutionarily ancient. MacLean called them the ‘visceral brain’ and suggested they mediate behaviourally ‘primitive’ functions inherited from lower mammals, particularly emotion and motivational behaviour. Although such phylogenetic arguments (based on comparison between species) are now commonly rejected, the concept of the limbic system survives and has since grown to be highly influential yet controversial.

First, there is no consensus over exactly which structures comprise the limbic system. Most schemes, however, consider it to consist of various parts of the cerebral cortex forming a set of ‘rings’ on the inner surface of each hemisphere, linked to a central core of structures lying below the cerebral cortex. The cortical areas include the cingulate cortex, hippocampus, parahippocampal cortex, and rhinal cortex. The various subcortical areas included in the limbic system extend down through the core of the brain to the upper part of the brain stem.

Second, there is considerable debate over what the function of the limbic system is. In addition to early ideas relating the limbic system to emotion and motivation, it has also now been implicated in the processing of sensory (especially olfactory) and cognitive information, learning and memory, sexual function (as part of a reward system serving emotional reactions), and motor functions. Most intriguing is the suggestion that the limbic system is concerned with mental integration of all functions related to personal ‘experience’.

As the number of brain areas said to belong to the limbic system has grown, its proposed functions have, not surprisingly, proliferated. It has been argued that such a heterogeneous collection of structures and functions can no longer be defined by a single general criterion and that the concept of the limbic system has become incoherent, even meaningless. An alternative view is that a quantitative approach (a ‘fuzzy limbic system’), in which different brain regions are described as having a certain degree of ‘limbic-ness’, would avoid the problem of having to define precise boundaries.

Despite controversy, the popularity and universal recognition of the term cannot be denied. This may be due partly to the very vagueness of the concept, which has often been used by authors as a convenience to refer to particularly poorly understood areas of the brain

Anatomy of the Brain

The image on the left is a side view of the outside of the brain, showing the major lobes (frontal, parietal, temporal and occipital) and the brain stem structures (pons, medulla oblongata and cerebellum).

The image on the right is a side view showing the location of the limbic system inside the brain. The limbic system consists of a number of structures, including the fornix, hippocampus, cingulate gyrus, amygdala, the parahippocampal gyrus and parts of the thalamus. The hippocampus is one of the first areas affected by Alzheimer's disease. As the disease progresses, damage extends throughout the lobes.
Glossary of Terms for an Anatomy of the Brain

Amygdala – limbic structure involved in many brain functions, including emotion, learning and memory. It is part of a system that processes "reflexive" emotions like fear and anxiety.

Cerebellum – governs movement.

Cingulate gyrus – plays a role in processing conscious emotional experience.

Fornix – an arch-like structure that connects the hippocampus to other parts of the limbic system.

Frontal lobe – helps control skilled muscle movements, mood, planning for the future, setting goals and judging priorities.

Hippocampus – plays a significant role in the formation of long-term memories.

Medulla oblongata – contains centers for the control of vital processes such as heart rate, respiration, blood pressure, and swallowing.

Limbic system – a group of interconnected structures that mediate emotions, learning and memory.

Occipital lobe – helps process visual information.

Parahippocampal gyrus – an important connecting pathway of the limbic system.

Parietal lobe – receives and processes information about temperature, taste, touch, and movement coming from the rest of the body. Reading and arithmetic are also processed in this region.

Pons – contains centers for the control of vital processes, including respiration and cardiovascular functions. It also is involved in the coordination of eye movements and balance.

Temporal lobe – processes hearing, memory and language functions.

Thalamus – a major relay station between the senses and the cortex (the outer layer of the brain consisting of the parietal, occipital, frontal and temporal lobes).

Autopsy

An autopsy is a medical procedure that consists of a thorough examination performed on a body after death, to evaluate disease or injury that may be present and to determine the cause and manner of a person's death.

The decision about an autopsy occurs at a difficult time for most families since they have just lost a loved one. Counselors or spiritual advisors who specialize in bereavement services may be available to help families through the process. Family members may consider an autopsy:
When a medical condition has not been previously diagnosed.
If there are questions about an unexpected death that appears due to natural causes.
If there are genetic diseases or conditions that they also may be at risk for developing.
When the death occurs unexpectedly during medical, dental, surgical, or obstetric procedures.
When the cause of death could affect legal matters.
When the death occurs during experimental treatment.
An autopsy may be required in deaths that have medical and legal issues and that must be investigated by the medical examiner's or coroner's office, the governmental office that is responsible for investigating deaths that are important to the public's health and welfare. Deaths that must be reported to and investigated by the medical examiner's or coroner's office can vary by state and may include those that have occurred:
Suddenly or unexpectedly, including the sudden death of a child or adult, or the death of a person who was not under the care of a doctor at the time of death.
As a result of any type of injury, including a fall, motor vehicle accident (MVA), drug overdose, or poisoning.
Under suspicious circumstances, such as a suicide or murder.
Under other circumstances defined by law.

In some of these deaths an autopsy may be required, and the coroner or medical examiner has the legal authority to order an autopsy without the consent of the deceased person's family (next of kin). If an autopsy is not required by law, it cannot be performed unless the deceased person's family provides permission.

An autopsy is generally performed by a doctor (pathologist) who has training and expertise in the examination of body tissues and fluids.

Should I have an autopsy done on my loved one?
Why It Is Done

An autopsy is done to:
Determine as precisely as possible what caused the death. This can sometimes provide family members with information about diseases or conditions that they also may be at risk for developing.
Confirm or exclude a disease diagnosis made before death (such as Alzheimer's disease). An autopsy also may be done to help understand how a given disease progresses or to determine the effectiveness of the treatment for that disease.
Document the presence of a disease that was undiagnosed before death.
Collect samples of body fluids or tissues for possible genetic testing. This is generally done only after discussion with the deceased person's family.
Collect evidence and information in criminal cases.
Help health departments or other government agencies identify and track a disease or potential public health hazard (such as a suspected contagious disease or contaminated drinking water).

What is DNA evidence?

Anything biological...
...blood, semen/sperm, hair,
...tissue, bones, organs, tooth pulp
...bodily secretions, saliva,
  ...sweat, urine, fingernails

DNA Evidence can be found virtually anywhere

- If it's biological, it's potential DNA evidence
- People constantly shed DNA
- There are 3,000,000,000,000 cells in the human body...only
about 100 are needed to obtain a DNA profile

There are two types of DNA testing used in criminal and non-criminal investigations:

Mitochondrial DNA:

1. Found in the cytoplasm of the cell
2. Runs along the maternal line  
- siblings share the same mitochondrial DNA
with their mother, grandmother, etc...
3. Can be found in hair shafts  
STR DNA

1. Found in the nucleus of the cell
2. PCR/STR DNA
3. Most commonly used in criminal
investigation casework

Uses of DNA in Criminal Investigations:

1. Identifying remains
2. Provides a Record of a particular person
being in a particular place
3. Ownership of personal items such as clothing
4. Determining Kinship

DNA collection

STR DNA technology changed the rules of evidence handling:
1. STR DNA increased sensitivity in testing
2. STR DNA increased awareness in evidence handling
  - As a result, the crime scene investigator must take great precautions to avoid
  the contamination of DNA evidence

In the past, all crime scenes needed to be protected against elements such as: Weather, Animals, 
and Traffic. With the inception of STR DNA testing, the crime scene investigator must also be 
concerned with scene contamination by crime scene personnel.

It is imperative that crime scene personnel take precautions to avoid contamination of DNA evidence:

1. Personal Protective Equipment (PPE) should be worn at all times.
- a single hair or drop of sweat from an unprotected person could leave an unknown DNA
 sample at the scene
2. When collecting DNA samples, the crime scene investigator should change gloves and forceps
after each item is collected, in order to avoid cross contamination between items of evidence
Documenting and Collecting DNA Samples:

1. Photograph stain/sample with and without a scale
2. Carefully swab the stain
  - preferably with no dilution
  - if stain is dry, use one drop of distilled water on the swab
3. Allow to air dry before packaging
4. Carefully label & seal (date, time, initials).
5. Maintain the chain of custody.
6. Provide information that you think may be important.
  - Note if items were collected from an unusual location or might  
  have possible contaminants.
7. Forward to the forensic lab ASAP

The proper collection and storage of biological evidence for DNA 
testing includes the following:

1. Biological evidence should be allowed to air dry before  
packaging.
  - ideally, it should be hung up in a clean dry room,
  away from direct sunlight
2. Biological evidence should be packaged in paper bags.
  - paper breaths, and allows the item of evidence to
  remain dry.
  - Plastic bags do not breath, and can cause moisture
  and mold to grow on the evidence, which in turn can
  have a negative affect on DNA testing
3. Biological evidence should be stored under laboratory
conditions as available resources permit - or in a
cool, dry climate, free of moisture
4. Place liquid items in collection tubes and refrigerate  

Before a DNA test can be performed, a control sample should be 
obtained from the victim, suspect, and any other persons whose DNA 
may be found on the item of evidence.

A control sample can be in the form of whole blood, a buccal swab, or 
any other known exemplar from the person in question. The easiest 
type of DNA control sample to obtain is a buccal swab. A buccal swab 
involves swabbing the inside of a person's cheek with an approved 
type of swab, for about 30 seconds, to secure the buccal cells that are 
found on the inside of the cheek. If done properly, a full DNA profile 
can be obtained from this swab.

–Before obtaining DNA control samples, consider having the person
in question sign a DNA consent form.  


DNA Collection:
RFLP (Restriction Fragment Length Polymorphism)
- this was the first type of DNA used in criminal investigations
- in order to run an RFLP test, a large biological sample was needed,
(usually at least the size of a quarter)
- this type of test usually provided a fairly discriminating result
- IE: a probability result of 1 in 1,000,000

PCR (Polymearse Chain Reaction) - first generation
- to run this type of test, a very small biological sample is needed, and that sample
can be amplified, or reproduced, to obtain a DNA profile
- the results are not as discriminating
- IE: a probability result of 1 in 25,000

STR (Short Tandem Repeat) second generation PCR
- This is the current form of DNA testing currently used in most forensic DNA labs.
STR testing provides the “best of both worlds”
- only a very small biological sample is required, (sometimes the sample is not even
visible to the naked eye.)
- STR DNA provides a very discriminating result
- IE: a probability result of 1 in 300,000,000,000

Age Determination

Although the actual age can not be determined by bones, the approximate age of the individual can be.

For age determination, different parts of the skeleton are more useful at different age ranges. The different age ranges include perinatal, neonate, infants and young children, late childhood, adolescence, young adult, and older adult.

The age of perinatals, those that are not yet born, can be determined by looking at bone size. This is because outside factors such as malnutrition on the mother's part is not going to affect the fetus' growth as much. During periods of low food intake the mother's body will give nutrients to the fetus, shorting the mother of nutrients.

Neonates, babies who have not gotten their teeth yet, are very difficult to accurately determine the age of because of individual variation of development. As a group, the neonates have no teeth, many areas of the skeleton have not fused together (especially the cranium and pelvis), and they have very small bones. 

Infants and young children will usually have some of their teeth in. The formation of teeth is often used in age determination for this group. Permanent teeth start to form at birth, thus the formation of permanent teeth is a relatively good age determinant. Some ossification has begun in the bones at this age, this means that soft parts of the bones become hard. However, this is not as good a determinant.

Late childhood is when the permanent teeth begin to come in. More bones begin to ossify.

Adolescence shows increased long bone length and fusion of the ends (or cap) to the shaft. This fusion is a particularly useful age technique. Each cap, or epiphysis, fuses to the shaft, or diaphysis, at a particular age range.

Young adults and older adults have several methods of age determination: closure of the cranial sutures; morphology of rib-ends, auricular surface and pubic symphysial; microstructure of bone and teeth; wear on teeth, incremental layers of cementum; and finally the 'Complex Method'. 

Cranial sutures (non-movable joints in the head) slowly fuse together, becoming obliterated in time. Although this has been known for many years, there has only been a weak association established between age and closure.

The morphology of rib-ends changes through age. Ribs are connected to the sternum by cartilage. The rib ends that meet with the cartilage are relatively flat at first, but during the aging process the ends become ragged and the cartilage becomes pitted. The irregularity of the rib ends has been found to relate to age at death.

The Circadian Clock: Good Rhythm May Play a Role in Type 2 Diabetes

Organisms ranging from bacteria to humans all rely on circadian rhythms as their molecular clocks. This complex network of molecular feedback loops not only helps to control wake-sleep patterns, but also helps to regulate body temperature, hormone levels, and metabolism, along with other systems. Whether it is from the disruption of sleep patterns through jetlag or seasonal affective disorder from the lack of sunlight, external stimuli can cause physical disturbances that are easily observable and can have serious outcomes. Along with these, perturbations can also occur that directly affect the molecular gears that keep the system running smoothly.

Although established Mendelian disorders such as familial advanced sleep-phase syndrome have been linked to circadian genes, complex disorders have remained more elusive. Recently, 3 papers published in Nature Genetics [1-3] reported such a link: a variant found within the melatonin receptor 1B (MTNR1B) is associated with both type 2 diabetes and fasting blood glucose levels.

Last summer, the first genome-wide association studies (GWAS) for fasting blood glucose levels were published using longitudinal cohorts.[4-6] Three markers were significantly associated. All were located in genes that were not surprising. The variants existed in the genes of glucokinase, glucokinase regulatory protein, and islet-specific glucose-6-phosphatase or glucose-6-phosphatase catalytic unit 2.[4-6] These 3 genes represented the most significant findings, but several other variants were near statistical significance after multiple hypothesis corrections for hundreds of thousands of tests. To gain statistical power, all 3 groups performed typing on an additional set of samples, thereby increasing their ability to discover alleles of lower penetrance. The 3 published papers represent the results of typing more than 60,000 individuals, leading to enough power to discern an association in MTNR1B as a true variant for fasting glucose levels.

Two papers, one by Lyssenko and colleagues[1] and the other by Prokopenko and colleagues on behalf of MAGIC (the Meta-Analysis of Glucose and Insulin-related traits Consortium),[2] along with several other groups who shared region-specific data, homed in on the same single nucleic polymorphism (SNP) within the MTNR1B locus. The SNP, rs10830963, maps to an 11.5-kilobase intron (regulatory region, not a protein-coding element) and does not appear to affect any known transcription factor-binding sites or cryptic splice sites. The effect of the variant reported from MAGIC and the additional cohorts of its meta-analysis, based on data from 35,812 subjects, had a per-allele effect of 0.072 mmol/L glucose and a P value of 3.2 x 10-50.[2] The 2 other studies, although they used slightly smaller datasets, showed a similar effect size and significance.

One difference in the study by Bouatia-Naji and colleagues[3] was that their highest association came from a different SNP, rs1387153. Although the strength of the association was very similar, this is a good example why functional analysis is the critical next step for all GWAS to determine the true causal variants. For MTNR1B, the true signal for association could be from either of the SNPs because they are in moderate linkage disequilibrium. Alternatively, the association could be from a separate variant for which the markers are both tagging. It is unlikely that the SNPs represent 2 separate signals because neither is significant after conditionally correcting for each other.

The ultimate goal of all GWAS is translation of the findings to a clinical setting, where they can have a positive impact on patients. However, this requires much more than just statistical significance. The current value of GWAS lies with the biological networks that the variant exposes as an underpinning of the phenotype. Both Lyssenko and colleagues[1] and Bouatia-Naji and colleagues[3] demonstrated direct expression of the MTNR1B gene in pancreatic beta cells. This finding, independently shown by both groups, reverses previous observations.[7] Preliminary data suggest that the G allele is linked with increased fasting blood glucose levels and may affect the MTNR1B transcription levels in the pancreatic islets of subjects older than 45 years of age.[1] 

These 3 papers provide another variant for fasting blood glucose levels, bringing the total attributable variance accounted for by the 4 known markers to around 1.5%.[2] It is of interest that while the association to fasting blood glucose levels is strong, the variant's link to type 2 diabetes is still very weak. This could be because conversion to type 2 diabetes status occurred in few patients in the longitudinal cohort during the study collection and follow-up periods. It could also be a hint that there are possible subtypes of diabetes that are manifested through different pathways, all of which lead to the same end-phenotype. Type 2 diabetes may actually represent several subtypes at the molecular, root level. Regardless, these findings strengthen prior research that our circadian rhythms can have strong influences on our metabolic system. Understanding and targeting malfunctions within our internal clock could prove a viable therapeutic strategy for type 2 diabetes

Can Insulin Be Delivered via Pneumatic Tube Systems?

insulin, like other protein pharmaceuticals, has a very well-defined structure, the integrity of which must be preserved to maintain its action. Unfortunately, conformational changes can occur due to physical, chemical, and thermal stresses causing protein denaturation and aggregation, ultimately leading to impaired activity or complete inactivity.[1] 

Shaking an insulin preparation can decrease the physical stability due to aggregation of the product, thereby lessening the potency. The actual protein structure can also be altered by denaturation. Mechanical stress such as vigorous shaking can cause visible clumping of the aggregates. However, the normal mechanical mixing ("rolling") of insulin suspensions to resuspend the product before administration should not cause instability.[2] 

In addition, use of external insulin pumps may cause unwanted insulin conformational changes and/or aggregation due to elevated temperature from body heat as well as mechanical agitation from activities of daily living.[3] 

Healthcare facilities, such as hospitals, often use pneumatic tube systems to facilitate the transportation of medications. These systems come in different shapes and sizes and use different forces for transport.[4] For these reasons, each facility is responsible for establishing its own guidelines pertaining to which medications can and cannot be sent via its pneumatic tube system, based on the system model the institution has implemented as well as the specific policies and procedures of the site.[5] Based on a review of guidelines for medication delivery via pneumatic tube system from several different hospitals, most do not send insulin or other protein-based drugs in this manner due to potential protein denaturation by mechanical stress.

A previously published statement from Eli Lilly and Company asserted that regular human insulin (Humulin®) and insulin lispro (Humalog®) products should not be delivered via the pneumatic tube system more than once and should have appropriate padding to deter breakage. No information is available on how tubing of insulin multiple times might affect the physical or chemical properties.[4] 

Based on the limited information available, it may not be advantageous to risk insulin instability in the interest of quick delivery. However, the final decision to send insulin by pneumatic tube should be based on the individual facility as well as any information that your tubing system manufacturer may be able to provide.

Finally, clinicians and patients should regularly inspect insulin products and discard any products with precipitants or changes in color or clarity.

انقلونزا الخنازير --swine flu

انفلونزا الخنازير والتي يسببها فيروس الانفلونزا " Influenza Virus " من النوع A تنتشر على شكل وباء في المناطق المصابة.. وهو من السلالة " H1N1 "..

ويتميز هذا النوع من الفيروسات بما يسمى " التحور الجيني - Antigenic Variation ".. والذي يستخدمه الفيروس
لإنتاج سلالات جديدة مختلفة الجينات.. وهذا هو محور الخطر في هذا المرض.. حيث أن هذه الخاصية تجعل من عملية احتواء الفيروس
ومكافحته وتصنيع اللقاحات الخاصة به عملية صعبة جدا..

المعرضون للإصابة بهذا الفيروس هم القريبون من الخنازير بشتى أصنافها.. كعمال مزارع الخنازير ومذابحها..
وللأسف الشديد.. فإن هذا الفيروس ينتقل من شخص لآخر أيضا عن طريق التنفس..
لذلك يعتبر هذا المرض من الأمراض الخطيرة التي يجب أن يتخذ لها الجميع الاحتياطات المناسبة لتجنب الإصابة بها..

وكما أوردت منظمة الصحة العالمية.. فإن هذا المرض لا تتم العدوى به من خلال لحوم ومنتجات الخنزير..
ولكن فقط من خلال استنشاقه أثناء التنفس.. خصوصا للقريبين من حيوانات أو أشخاص مصابين..

والقلق العالمى الحالى من المرض يتمثل فى أن أكثر الفئات العمرية إصابة به من الشباب فى حين أن الأنفلونزا العادية تصيب صغار السن أو كبار السن وتلك الفئة العمرية لم تصب حتى الآن فى المكسيك (أولى الدول في ظهور المرض ) ومعظم الإصابات بين الشباب .

وتتمثل أعراض المرض فى ارتفاع فى درجات الحرارة وكحة وألم بالجسم وصداع ورشح أو زكام وفى بعض الحالات قد يحدث قىء وإسهال، وفقدان الوعى الذى يمكن أن ينتهى بالوفاة .



والوقاية من انفلونزا الخنازير تبدأ بغسل الايدى بالماء والصابون عدة مرات بعد التعرض للحيوانات ، بالاضافة إلى الحذر الشديد أثناء التعامل مع الحيوانات المصابة والإبلاغ الفورى عند ظهور أية أعراض تشابه أعراض انفلونزا الخنازير خاصة اذا كان المبلغ مخالطا للخنازير ، وسحب عينات من انف وحلق المصاب للتأكد من إصابته بالفيروس .

كذلك ينبغي القيام بعادات النظافة العامة.. مثل غسيل اليدين بصفة متكررة، وتجنب الاتصال بالمرضى والابتعاد بقدر الإمكان عن الأماكن المزدحمة والغير نظيفة.. مع الراحة الجيدة والتغذية السليمة
 
لا أحد يعلم متى سوف تنتهي أزمة أنفلونزا الطيور التي حلت على معظم أنحاء الكرة الأرضية، فكل العلامات تشير إلي مواصلة انتشار هذا الفيروس حتى انتقل إلي الخنازير، ففي الوقت التي تحاول فيه الدول مواجهة هذا الفيروس، أعلنت منظمة الصحة العالمية عن انتشار حالات بشرية من أنفلونزا الخنازير التي تضرب المكسيك والولايات المتحدة، الأمر الذي يجعله قد يتحول إلى وباء عالمي ليصبح مصدر قلق يهدد العالم بأسره.

وتسبب ظهور فيروس أنفلونزا الخنازير في حالة من الذعر في الأمريكتين‏,‏ تحسبا للانتشار السريع لوباء جديد وفتاك‏,‏ ينتقل من الحيوانات الأكثر رواجا هناك إلي البشر‏.
وقد أعلن وزير الصحة المكسيكي جوزيه إنجيل، أن عدد ضحايا أنفلونزا الخنازير في البلاد ارتفع إلى 81 شخصاً خلال شهر أبريل الجاري.

وأكدت مارجريت تشان مدير عام منظمة الصحة العالمية، أن أنفلونزا الخنازير تنطوي على سلالة من فيروس "H1N1" الذي يمكن أن يتحول إلى وباء متفشٍ، مشيرة إلى أنه من المبكر التنبؤ بما إذا كانت أنفلونزا الخنازير ستنتشر في كافة أنحاء العالم أم لا.
وأكدت تشان أن المعلومات المتوافرة عن مرض أنفلونزا الخنازير لا تزال غير كافية، كما أن طبيعة المرض لا تزال تتضح يوماً بعد يوم.

ودعت المنظمة دول العالم إلى توخي الحيطة والحذر من تفشي فيروسات مشابهة بعد اكتشاف سلالات مرتبطة بالمرض في كل من المكسيك والولايات المتحدة.

وقد اتخذت السلطات الصحية في المكسيك إجراءات وقائية عاجلة، وأضافت المنظمة أن المرض الذي ينتقل من شخص إلى آخر أصبح يشكل "وضعاً خطيراً" يجب مراقبته جيداً.

ويعني إعلان المنظمة أنه يتعين على دول العالم كافة تصعيد إجراءات الرقابة والإبلاغ عن حالات انتشار المرض وخصوصا في أوساط الشباب البالغين.

وكانت منظمة الصحة العالمية قد أعلنت اعتزامها اتخاذ إجراءات طارئة من جانبها للسيطرة على الفيروس، إذ نصحت كل أعضائها بضرورة الاحتراس من انتشار أنفلونزا موسمية غير معتادة، وخاصة بين البالغين الأصحاء.

وكانت السلطات الصحية الأمريكية قد حذرت في وقت سابق من انتشار الفيروس، معلنة عن ظهور حالات جديدة، وبلغ عدد حالات الإصابة بالمرض المعلن عنها في الولايات المتحدة 8 حالات، كان آخرها طفل يعيش في ولاية كاليفورنيا، كما وصلت العدوى إلى ولاية تكساس أيضاً، وقد تعافى كل المصابين من المرض عدا واحد فقط لا يزال خاضعاً للعلاج.
وحذَّر الخبراء من ضرورة اتخاذ الاحتياطات اللازمة لمنع انتشار المرض، وكان بعض العلماء قد حذروا منذ سنوات من احتمال ظهور أوبئة ناجمة عن فيروسات تحمل عناصر جينية من كل من البشر والحيوانات.