Friday, January 23, 2009
Thursday, January 22, 2009
Pathophysiology and Aging of Bone
Sources: http://www.springerlink.com/content/x208624555xgu576/
This is an article in regards to pathophysiology and aging of bone by Peitschmann et al.
I will list out the points of interest in this article.
Bone loss due to aging:
1) overall decline in protein synthesis and protein turnover and accumulation of damaged molecules
2) number of adhesion colony forming cells significantly lower in marrow cells
3) requirement of higher concentration of growth factors and hormones
==> Impaired growth of human endosteal bone cells from men aged over 50 years
4) lower production of osteocalcin after stimulation with 1,25-(OH)2D3
Age related osteopenia may result from inversely related changes in pool size of hematopoietic osteoclast precursor cells and osteogenic stromal cells; reduced production of osteoprotegerin and enhanced RANKL expression would additionally promote the formation of osteoclasts.
Currently available markers of bone formation are:
total and bone-specific alkaline phosphatase activity, osteocalcin and type I collagen terminal extension peptides.
Bone resorption is assessed by
urinary excretion or serum levels of bone type I collagen degradation products eg. pyridinium crosslink and N- and C-telopeptide of collagen crosslinks.
Factors affecting invidividual bone mass include:
A) Peak bone mass (the amount of bone mass achieved at skeletal maturity)
B) Subsequent rate of bone loss
What is bone quality, one may ask. According to Mary Bouxsein: "the totality of features and characteristics that influence a bone's ability to resist fractures". Nevertheless, compromised trabecular architecture portrays as an independent causal factor in the pathogenesis of vertebral fractures.
It is well established that estrogen deficiency is a major determinant of the accelerated bone loss in postmenopausal women. This leads to the most infamous term called "osteoporosis" which everyone in the world knows and aware about it. One of the major worry which medical personnals are concerned of is the fracture of the neck of the femur in osteoporotic patients. Of course there are other fractures that could happen in osteoporotic bone in this case, eg. Colles fracture and crush fractures of thoracic and lumbar verterbra. For short, osteoporosis contributes in the increment of fragility (low energy) fractures and severity of traumatic (high energy) fractures.
HORMONAL INFLUENCES IN BONE LOSS
Androgen deficiency can impale high-turnover osteopenia in males (be it rats or males). Unfortunately, there isn't a clear distinction in this statement as some studies quoted positive correlation between free androgen index and femoral neck bone mineral density. It is interesting to note that in the study conducted by Kelly and coworkers (1990) reported that radial bone mineral density could be predicted by an index of free testosterone and weight. However, the fact that bioavailable estrogen was most strongly associated with bone mineral density, and thus, bioavailable of estrodiol rather than testosteonr is used as the most consistent predictors of bone turnoever and bone loss. There is another possible role of using dehydroepiandrosterone (DHEA) and DHEA sulfate to correlate bone density in healthy women.
OTHER INFLUENCE
We know that growth hormones stimulate growth. Nevertheless it stimulates the growth of bones. It is not surprising to note that growth hormone secretion declines as we age. Role of growth hormone/insulin-like growth factor is clearly shown in cases with growth hormone deficiency, leading to dwarfism and acromegaly in cases of excess growth hormones. 1,25-dihydroxyvitamin D3 acts as a central regulator of calcium and phosphorus homeostasis. It is interesting to note that there exists an association between bone mineral density and vitamin D receptor allele. As shown in literatures, vitamin D receptor polymorphisms appear to influence bone mineral density in primary as well as secondary osteoporosis.
To summarize, estrogen deficiency acts as the major determinant of bone loss in women and men whilst Vit D3 portray as a factor of bone turnover in elderly.
RIGGS, KHOSLA AND MELTON UNITARY MODEL OF INVOLUTIONAL OSTEOPOROSIS
Involutional osteoporosis is defined as the common form of osteoporosis that begins in middle life and becomes increasingly more frequent with age and there are two tyesp: type I ("postmenopausal") and type II ("senile").
Type I osteoporosis presents during the first 15-20 years after menopause and is characterized by excessive loss of trabecular bone, which causes the fractures typical of postmenopausal osteoporosis such as vertebral fractures and Colles' fracures. Type II is characterized by loss of trabecular and cortical bone, and the most frquent fractures involve the proximal femur and vertebra.
One point of interesting note is that cigarette smoking has been identified as risk factor for low bone mineral density. It is shown that 25-OH vitamin D and osteocalcin levels are low in smokers. Impairment of intestinal calcium absorption may contribute to the bone loss as well.
To conclude, humans will get old, we can get old. Nevertheless, with the understanding of these conditions, it is possible that one can prevent osteoporosis by doing the right activities to minimize of one's risk of getting osteoporosis. So start a healthy diet, do exercise and stop smoking!!!
This is an article in regards to pathophysiology and aging of bone by Peitschmann et al.
I will list out the points of interest in this article.
Bone loss due to aging:
1) overall decline in protein synthesis and protein turnover and accumulation of damaged molecules
2) number of adhesion colony forming cells significantly lower in marrow cells
3) requirement of higher concentration of growth factors and hormones
==> Impaired growth of human endosteal bone cells from men aged over 50 years
4) lower production of osteocalcin after stimulation with 1,25-(OH)2D3
Age related osteopenia may result from inversely related changes in pool size of hematopoietic osteoclast precursor cells and osteogenic stromal cells; reduced production of osteoprotegerin and enhanced RANKL expression would additionally promote the formation of osteoclasts.
Currently available markers of bone formation are:
total and bone-specific alkaline phosphatase activity, osteocalcin and type I collagen terminal extension peptides.
Bone resorption is assessed by
urinary excretion or serum levels of bone type I collagen degradation products eg. pyridinium crosslink and N- and C-telopeptide of collagen crosslinks.
Factors affecting invidividual bone mass include:
A) Peak bone mass (the amount of bone mass achieved at skeletal maturity)
B) Subsequent rate of bone loss
What is bone quality, one may ask. According to Mary Bouxsein: "the totality of features and characteristics that influence a bone's ability to resist fractures". Nevertheless, compromised trabecular architecture portrays as an independent causal factor in the pathogenesis of vertebral fractures.
It is well established that estrogen deficiency is a major determinant of the accelerated bone loss in postmenopausal women. This leads to the most infamous term called "osteoporosis" which everyone in the world knows and aware about it. One of the major worry which medical personnals are concerned of is the fracture of the neck of the femur in osteoporotic patients. Of course there are other fractures that could happen in osteoporotic bone in this case, eg. Colles fracture and crush fractures of thoracic and lumbar verterbra. For short, osteoporosis contributes in the increment of fragility (low energy) fractures and severity of traumatic (high energy) fractures.
HORMONAL INFLUENCES IN BONE LOSS
Androgen deficiency can impale high-turnover osteopenia in males (be it rats or males). Unfortunately, there isn't a clear distinction in this statement as some studies quoted positive correlation between free androgen index and femoral neck bone mineral density. It is interesting to note that in the study conducted by Kelly and coworkers (1990) reported that radial bone mineral density could be predicted by an index of free testosterone and weight. However, the fact that bioavailable estrogen was most strongly associated with bone mineral density, and thus, bioavailable of estrodiol rather than testosteonr is used as the most consistent predictors of bone turnoever and bone loss. There is another possible role of using dehydroepiandrosterone (DHEA) and DHEA sulfate to correlate bone density in healthy women.
OTHER INFLUENCE
We know that growth hormones stimulate growth. Nevertheless it stimulates the growth of bones. It is not surprising to note that growth hormone secretion declines as we age. Role of growth hormone/insulin-like growth factor is clearly shown in cases with growth hormone deficiency, leading to dwarfism and acromegaly in cases of excess growth hormones. 1,25-dihydroxyvitamin D3 acts as a central regulator of calcium and phosphorus homeostasis. It is interesting to note that there exists an association between bone mineral density and vitamin D receptor allele. As shown in literatures, vitamin D receptor polymorphisms appear to influence bone mineral density in primary as well as secondary osteoporosis.
To summarize, estrogen deficiency acts as the major determinant of bone loss in women and men whilst Vit D3 portray as a factor of bone turnover in elderly.
RIGGS, KHOSLA AND MELTON UNITARY MODEL OF INVOLUTIONAL OSTEOPOROSIS
Involutional osteoporosis is defined as the common form of osteoporosis that begins in middle life and becomes increasingly more frequent with age and there are two tyesp: type I ("postmenopausal") and type II ("senile").
Type I osteoporosis presents during the first 15-20 years after menopause and is characterized by excessive loss of trabecular bone, which causes the fractures typical of postmenopausal osteoporosis such as vertebral fractures and Colles' fracures. Type II is characterized by loss of trabecular and cortical bone, and the most frquent fractures involve the proximal femur and vertebra.
One point of interesting note is that cigarette smoking has been identified as risk factor for low bone mineral density. It is shown that 25-OH vitamin D and osteocalcin levels are low in smokers. Impairment of intestinal calcium absorption may contribute to the bone loss as well.
To conclude, humans will get old, we can get old. Nevertheless, with the understanding of these conditions, it is possible that one can prevent osteoporosis by doing the right activities to minimize of one's risk of getting osteoporosis. So start a healthy diet, do exercise and stop smoking!!!
Tuesday, January 20, 2009
Obs & Gyn
This is from: http://ob-ultrasound.net/
Written here are the 4 lengths discussed during my lecture dated 21st Jan 2009. Though it is MSK week, there are couple of things the lecturer wants us to know.
Determination of gestational age and assessment of fetal size.
Fetal body measurements reflect the gestational age of the fetus. This is particularly true in early gestation. In patients with uncertain last menstrual periods, such measurements must be made as early as possible in pregnancy to arrive at a correct for the patient. In the latter part of pregnancy measuring body parameters will allow assessment of the size and growth of the fetus and will greatly assist in the diagnosis and management ofintrauterine growth retardation (IUGR).
The following measurements are usually made:
a) The Crown-rump length (CRL)
This measurement can be made between 7 to 13 weeks and gives very accurate estimation of the gestational age. Dating with the CRL can be within 3-4 days of the last menstrual period. An important point to note is that when the due date has been set by an accurately measured CRL, it should not be changed by a subsequent scan. For example, if another scan done 6 or 8 weeks later says that one should have a new due date which is further away, one should not normally change the date but should rather interpret the finding as that the baby is not growing at the expected rate.
b) Biparietal diameter(BPD)
The diameter between the 2 sides of the head. This is measured after 13 weeks. It increases from about 2.4 cm at 13 weeks to about 9.5 cm at term. Different babies of the same weight can have different head size, therefore dating in the later part of pregnancy is generally considered unreliable. Dating using the BPD should be done as early as is feasible.
c) The Femur length (FL)
Measures the longest bone in the body and reflects the longitudinal growth of the fetus. Its usefulness is similar to the BPD. It increases from about 1.5 cm at 14 weeks to about 7.8 cm at term. Similar to the BPD, dating using the FL should be done as early as is feasible.
d) The Abdominal circumference (AC)
The single most important measurement to make in late pregnancy. It reflects more of fetal size and weight rather than age. Serial measurements are useful in monitoring of the fetus. AC measurements should not be used for dating a fetus.
The weight of the fetus at any gestation can also be estimated with great accuracy using polynomial equations containing the BPD, FL, and AC. computer softwares and lookup charts are readily available. For example, a BPD of 9.0 cm and an AC of 30.0 cm will give a weight estimate of 2.85 kg.
Written here are the 4 lengths discussed during my lecture dated 21st Jan 2009. Though it is MSK week, there are couple of things the lecturer wants us to know.
Determination of gestational age and assessment of fetal size.
Fetal body measurements reflect the gestational age of the fetus. This is particularly true in early gestation. In patients with uncertain last menstrual periods, such measurements must be made as early as possible in pregnancy to arrive at a correct for the patient. In the latter part of pregnancy measuring body parameters will allow assessment of the size and growth of the fetus and will greatly assist in the diagnosis and management ofintrauterine growth retardation (IUGR).
The following measurements are usually made:
a) The Crown-rump length (CRL)
This measurement can be made between 7 to 13 weeks and gives very accurate estimation of the gestational age. Dating with the CRL can be within 3-4 days of the last menstrual period. An important point to note is that when the due date has been set by an accurately measured CRL, it should not be changed by a subsequent scan. For example, if another scan done 6 or 8 weeks later says that one should have a new due date which is further away, one should not normally change the date but should rather interpret the finding as that the baby is not growing at the expected rate.
b) Biparietal diameter(BPD)
The diameter between the 2 sides of the head. This is measured after 13 weeks. It increases from about 2.4 cm at 13 weeks to about 9.5 cm at term. Different babies of the same weight can have different head size, therefore dating in the later part of pregnancy is generally considered unreliable. Dating using the BPD should be done as early as is feasible.
c) The Femur length (FL)
Measures the longest bone in the body and reflects the longitudinal growth of the fetus. Its usefulness is similar to the BPD. It increases from about 1.5 cm at 14 weeks to about 7.8 cm at term. Similar to the BPD, dating using the FL should be done as early as is feasible.
d) The Abdominal circumference (AC)
The single most important measurement to make in late pregnancy. It reflects more of fetal size and weight rather than age. Serial measurements are useful in monitoring of the fetus. AC measurements should not be used for dating a fetus.
The weight of the fetus at any gestation can also be estimated with great accuracy using polynomial equations containing the BPD, FL, and AC. computer softwares and lookup charts are readily available. For example, a BPD of 9.0 cm and an AC of 30.0 cm will give a weight estimate of 2.85 kg.
Tuesday, January 6, 2009
Clinical Trigger for CME Clinical Anatomy at 10th Jan 2009
Session 1 9.45 AM Anterior Abdominal Wall
Facilitator: AP Joachim Perera
Clinical Trigger I (30 minutes)
A 25-year-old man presents to a surgical clinic with a dull, ‘dragging’ pain in his left groin, which has persisted for some months. A lump is felt at the medial end of his left groin extending to the scrotum. The lump increases in size when he stands up and when coughing. The doctor diagnoses of him having an indirect inguinal hernia.
Areas of discussion:
§ Anatomy of the inguinal canal and scrotum
§ Inguinal mechanisms in preventing hernias
§ Anatomical basis of direct and indirect inguinal hernias
§ Anatomical basis of differentiating between inguinal and femoral hernias
Questions of interest:
How much of the inguinal canal is traversed by an indirect inguinal hernia?
Which structure lies immediately medial to the deep inguinal ring?
Which layer covering the spermatic cord corresponds to the Internal Oblique muscle of the anterior abdominal wall?
How would you identify the Vas Deferens clinically in the living subject?
Which anatomical structure causes femoral hernia to get strangulated very often?
Facilitator: AP Joachim Perera
Clinical Trigger I (30 minutes)
A 25-year-old man presents to a surgical clinic with a dull, ‘dragging’ pain in his left groin, which has persisted for some months. A lump is felt at the medial end of his left groin extending to the scrotum. The lump increases in size when he stands up and when coughing. The doctor diagnoses of him having an indirect inguinal hernia.
Areas of discussion:
§ Anatomy of the inguinal canal and scrotum
§ Inguinal mechanisms in preventing hernias
§ Anatomical basis of direct and indirect inguinal hernias
§ Anatomical basis of differentiating between inguinal and femoral hernias
Questions of interest:
How much of the inguinal canal is traversed by an indirect inguinal hernia?
Which structure lies immediately medial to the deep inguinal ring?
Which layer covering the spermatic cord corresponds to the Internal Oblique muscle of the anterior abdominal wall?
How would you identify the Vas Deferens clinically in the living subject?
Which anatomical structure causes femoral hernia to get strangulated very often?
Clinical trigger II (10 minutes)
Given below is a picture of a small tense and tender mass in the right groin of a 70-year-old woman.
She presented with clinical features intestinal obstruction.
Diagnose the condition. Explain anatomical reasons for the diagnosis.
Clinical trigger III (30 minutes)
A 50 years old man presented with generalized abdominal pain of one day’s duration. He has a history of constant upper abdominal pain and heartburn for last 2 years, which was often relieved by over-the-counter antacids.
An erect X ray of the abdomen was done which showed gas shadow under the right dome of the diaphragam.
What is the most proble diagnosis?
Given below is a picture of a small tense and tender mass in the right groin of a 70-year-old woman.
She presented with clinical features intestinal obstruction.
Diagnose the condition. Explain anatomical reasons for the diagnosis.
Clinical trigger III (30 minutes)
A 50 years old man presented with generalized abdominal pain of one day’s duration. He has a history of constant upper abdominal pain and heartburn for last 2 years, which was often relieved by over-the-counter antacids.
An erect X ray of the abdomen was done which showed gas shadow under the right dome of the diaphragam.
What is the most proble diagnosis?
Areas of discussion:
Based on the picture given below, discuss lesser sac, greater omentum and greater sac
Structure and blood vessels of stomach
Based on the picture given below, discuss lesser sac, greater omentum and greater sac
Structure and blood vessels of stomach
Questions of interest:
A surgical incision through fundus of stomach will require clamping of which artery?
Which artery is lying in close relation to lesser sac and is well visible because of tortuous nature?
Why ulcers are more common over lesser curvature of the stomach?
Session 2 11.00 AM Head Injuries
Facilitator: Dr Nilesh Kumar
Clinical Trigger IV (30 minutes)
A 15-year-old baseball player was hit by a baseball over the right temple area. He lost consciousness briefly but woke up after about 45 seconds and had no neurological deficits. He was taken to the emergency room and seemed to be in good condition.
Four hours later, while being observed, he complained of an increasing headache and had a seizure. On examination, the patient’s right pupil appeared dilated and reacted sluggishly to light. The neurosurgeon was concerned about the increased intracranial pressure.
What is the most likely diagnosis?
Areas of discussion:
· Anatomical explanation of the causative condition causing increased intracranial pressure.
· Arrangement of the meningeal layers in the cranial cavity
· Dural folds and intracranial venous sinuses (Related structures of importance)
· Vascular supply to the meninges
· Anatomical explanation of the causative condition causing increased intracranial pressure.
· Arrangement of the meningeal layers in the cranial cavity
· Dural folds and intracranial venous sinuses (Related structures of importance)
· Vascular supply to the meninges
Questions of interest:
What are the vessels, which carry infections from the scalp to the venous sinuses?
What is the danger area of the face? Why is it called so?
How can a scalp injury produce a black eye?
Clinical trigger V (30 minutes)
One morning, while shaving, a 65-year-old industrial worker noticed in the mirror that he was unable to elevate his left upper eyelid. The doctor found the left eyelid to be drooped (ptosis). He also told the doctor that left side of his face was flushed and felt warm but there was no sweating even in the intense heat of the factory. The doctor observed that the left side pupil was constricted and the other eye was unaffected.
The man’s medical record showed that he was a heavy smoker. The doctor advised a chest radiograph, which revealed a shadow at the apex of the left lung indicative of a cancer.
Explain the anatomical basis of the patient’s presenting symptoms.
What are the vessels, which carry infections from the scalp to the venous sinuses?
What is the danger area of the face? Why is it called so?
How can a scalp injury produce a black eye?
Clinical trigger V (30 minutes)
One morning, while shaving, a 65-year-old industrial worker noticed in the mirror that he was unable to elevate his left upper eyelid. The doctor found the left eyelid to be drooped (ptosis). He also told the doctor that left side of his face was flushed and felt warm but there was no sweating even in the intense heat of the factory. The doctor observed that the left side pupil was constricted and the other eye was unaffected.
The man’s medical record showed that he was a heavy smoker. The doctor advised a chest radiograph, which revealed a shadow at the apex of the left lung indicative of a cancer.
Explain the anatomical basis of the patient’s presenting symptoms.
Areas of discussion:
· Discussion about the structures of the head and neck affected to produce the symptoms
· Pathway of direct and consensual light reflex
· Nervous mechanism of sweating
Session 3 1.00 PM Neck Lymph nodes, Deep cervical fascia
Facilitator: Dr Daw Khin Win
Clinical Trigger VI (30 minutes)
A 50 years old farmer came to the OPD with a lump in the left side of the neck. He noticed the lump about 2 weeks ago. It was not tender nor had any discharge. He also noticed he had been salivating a lot and had a sore on the side of his tongue. He has a habit of chewing tobacco since he was 30 years old and he also used to smoke 3 to5 cigarettes daily.
On examination, the patient’s jugulo-digastric nodes were found to be enlarged. They were mobile, not fixed to the surrounding tissue, not tender but stony hard. The examining doctor also found an ulcer on the left side of the anterior two third of the tongue.
Areas of discussion:
Extrinsic and intrinsic muscles of the tongue
Nerve supply of the tongue - sensory, motor
Lymphatic drainage of the tongue
Superficial and deep lymph nodes of head and neck
MSKCC (Head and Neck Service at Memorial Sloan-Kettering Centre) method of describing nodal groups of level I to level V
Clinical trigger VII (30 minutes)
A 45-year-old labourer presented with a lump in his right axilla. It was small at first but increased in size slowly during the past one month. Now pus was coming out from a small sinus from the lump and it had become tender. He said he felt hot and sweaty in the evenings.
On taking past medical history, it was found that he had been losing weight and had sever pain in his neck when he moved his neck. He said he was under antiTB treatment regime for a swelling of neck lymph glands about 5 years ago and stopped the treatment about 3 years back.
He was admitted to drain the abscess and for further investigations.
Explain the anatomical basis for the patient’s presenting symptoms
· Discussion about the structures of the head and neck affected to produce the symptoms
· Pathway of direct and consensual light reflex
· Nervous mechanism of sweating
Session 3 1.00 PM Neck Lymph nodes, Deep cervical fascia
Facilitator: Dr Daw Khin Win
Clinical Trigger VI (30 minutes)
A 50 years old farmer came to the OPD with a lump in the left side of the neck. He noticed the lump about 2 weeks ago. It was not tender nor had any discharge. He also noticed he had been salivating a lot and had a sore on the side of his tongue. He has a habit of chewing tobacco since he was 30 years old and he also used to smoke 3 to5 cigarettes daily.
On examination, the patient’s jugulo-digastric nodes were found to be enlarged. They were mobile, not fixed to the surrounding tissue, not tender but stony hard. The examining doctor also found an ulcer on the left side of the anterior two third of the tongue.
Areas of discussion:
Extrinsic and intrinsic muscles of the tongue
Nerve supply of the tongue - sensory, motor
Lymphatic drainage of the tongue
Superficial and deep lymph nodes of head and neck
MSKCC (Head and Neck Service at Memorial Sloan-Kettering Centre) method of describing nodal groups of level I to level V
Clinical trigger VII (30 minutes)
A 45-year-old labourer presented with a lump in his right axilla. It was small at first but increased in size slowly during the past one month. Now pus was coming out from a small sinus from the lump and it had become tender. He said he felt hot and sweaty in the evenings.
On taking past medical history, it was found that he had been losing weight and had sever pain in his neck when he moved his neck. He said he was under antiTB treatment regime for a swelling of neck lymph glands about 5 years ago and stopped the treatment about 3 years back.
He was admitted to drain the abscess and for further investigations.
Explain the anatomical basis for the patient’s presenting symptoms
Areas of discussion:
Prevertebral and post vertebral muscles
Superficial cervical fascia — nerves and vessels
Arrangement of deep fascia of the neck
Investing layer of deep cervical fascia
Pretracheal layer and its importance
Fascial compartments of the neck
Prevertebral space
Prevertebral and post vertebral muscles
Superficial cervical fascia — nerves and vessels
Arrangement of deep fascia of the neck
Investing layer of deep cervical fascia
Pretracheal layer and its importance
Fascial compartments of the neck
Prevertebral space
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