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Biomedical subjects

C J Nel

Publications and source records attributed to C J Nel.

At least 37 records · Page 2Linked to original sources
PubMed1991

Multiple endocrine neoplasia type 2A (MEN 2A) syndrome in a South African family. Biochemistry and molecular genetics.

Multiple endocrine neoplasia type 2A (MEN 2A), an uncommon heritable disease, was investigated in an Afrikaner kindred. Serum calcitonin levels after combined pentagastrin and calcium chloride stimulation were measured to determine thyroid involvement, as were urinary metadrenalin levels to determine adrenal gland involvement. MEN 2A genotype status was determined using the DNA probe MCK2 (D10S15). The index patient, who showed both thyroid and adrenal gland involvement, died of phaeochromocytoma complications. Thirty-four of his 114 family members, in 4 generations, were investigated. Nine had positive histological and calcitonin tests and were predicted to be MEN 2A genotypes by DNA analysis. One asymptomatic individual had a positive calcitonin test after being predicted to be a MEN 2A genotype with the probe MCK2. In 3 DNA-positive cases calcitonin stimulation tests were negative. Preclinical detection of the heritable form of MEN 2A will be facilitated by utilising the DNA probe MCK2 to determine carrier status in this large South African family. It is also the first South African family in which biochemical and molecular genetic techniques were used to facilitate diagnosis.

Adolescent↗
PubMed1991

Early thyroidectomy for medullary thyroid carcinoma in children and young adults with the multiple endocrine neoplasia type 2A (MEN 2A) syndrome.

A South African family, at risk for the multiple endocrine neoplasia type 2A (MEN 2A) syndrome, was identified. The Bloemfontein MEN Study Group was founded, inter alia, to study the effects of early detection of medullary carcinoma of the thyroid (MTC) and treatment by total thyroidectomy in children and young adults with MEN 2A. Genotypes were identified by DNA probe and MTC diagnosed by basal and stimulated calcitonin levels. Between 1986 and 1989, 10 members of the family underwent total thyroidectomy and central lymph node dissection for MTC. There were 6 female and 4 male patients (mean age 22,0 years; range 10 - 35 years). Histological examination of the resected thyroid revealed MTC in all patients; 8 had bilateral disease and 2 unilateral. Lymph nodes were negative for MTC in all patients. None of the patients suffered injury to the recurrent nerve, while 1 experienced transient hypoparathyroidism postoperatively. Replacement therapy is maintaining thyroid hormone levels in all patients. Screening should probably begin at the age of 1 year, and total thyroidectomy should be performed when an elevated calcitonin level is observed.

Adolescent↗
PubMed1991

[Gallstone disease in the elderly].

The clinical manifestations, management and outcome of gallstone disease in 100 elderly patients are described. A total of 65 patients presented with a complication, acute cholecystitis (43), gallstone pancreatitis (8) and obstructive jaundice (6) being the commonest manifestations. The clinical picture was often misleadingly mild. Associated disease occurred in 70 patients but precluded surgery in only 3. Emergency surgery was indicated in 18 patients. Surgery was performed on 96 patients (cholecystostomy 2, cholecystectomy 94); 35 explorations of the common bile duct were done, with stones present in 33. Four patients died, 1 following an endoscopic retrograde cholangiopancreatography (ERCP) and 3 postoperatively (2 patients with gallstone pancreatitis); no death occurred following an elective operation. Alternative modalities of treatment of gallstone are expected to play a minor role in the management of gallstone disease in the elderly.

Aged↗
PubMed1990

Detecting asymptomatic coronary artery disease using routine exercise testing and exercise thallium scintigraphy in patients with atherosclerotic vascular disease.

ECG-monitored exercise testing has been proposed as a relatively inexpensive and effective means of screening for asymptomatic coronary artery disease in patients presenting for peripheral vascular surgery. Despite the fact that exercise thallium scintigraphy is also dependent on the patient's ability to exercise, using this test in conjunction with ECG-monitored exercise testing may enhance sensitivity and specificity of non-invasive evaluation. Thirty-two patients were subjected to ECG-monitored exercise testing, exercise thallium scintigraphy and coronary angiography. The sensitivity of ECG-monitored exercise testing for detecting coronary artery disease was calculated at 81.8% and the specificity at 87.5%, while the figures for exercise thallium scintigraphy were 73.1% and 33.3% respectively. Using these two methods in combination yielded a predictive accuracy of 90.6%. The only advantage of exercise thallium scintigraphy over exercise ECG appears to be in patients in whom the latter test could not be interpreted or was non-diagnostic.

Adult↗
PubMed1990

Risk factors for atherosclerosis--can they be used to identify the patient with multisystem atherosclerosis?

Risk factors are often used in preventive care programmes to identify the patient at particular risk for developing atherosclerosis. Risk factors for atherosclerosis have also been shown to be linked to the presence of the disease at a given time, a fact that may be helpful when screening for additional atherosclerotic disease in the known arteriopath. Risk factors were recorded in 471 patients admitted to hospital with symptoms of atherosclerosis. In patients admitted primarily with peripheral vascular disease, risk factors linked to the presence of additional coronary artery disease were a family history of ischaemic heart disease (odds ratio = 2.6), the presence of carotid artery disease (odds ratio = 1.9) and high fasting serum triglyceride levels (P less than 0.04). Grouping these factors together using logistic regression, ischaemic heart disease could be predicted with a sensitivity of 72% and a specificity of 43%. Patients admitted with carotid artery disease were more likely to have ischaemic heart disease in the presence of peripheral vascular disease (odds ratio = 1.9) and a raised serum cholesterol level (P less than 0.02), while female gender (odds ratio = 2.9) and an increase in age (P less than 0.001) were linked to an increased prevalence of concomitant atherosclerosis in patients admitted with acute myocardial infarction or for elective coronary artery bypass surgery. Using an age cut-off point, additional atherosclerosis could be predicted with a sensitivity of 32% and a specificity of 88% in these patients.

Adult↗
PubMed1990

Atherosclerosis--multi-organ involvement the rule rather than the exception.

Atherosclerosis is a systemic disorder and significant lesions often occur in organ systems other than the symptomatic area. Three groups of patients, those admitted to hospital with either coronary artery disease, carotid artery stenosis or peripheral vascular disease, were examined for concomitant atherosclerotic lesions. Non-invasive tests, namely duplex scanning of the carotid arteries, arm ergometer exercise testing, and segmental pressure of the limbs, were used during evaluation. A clear association between ischaemic heart disease, carotid artery stenosis and femoropopliteal disease was found. Women appear to be more prone to multi-organ involvement than men; their higher average age on admission to hospital is a possible explanation for this in some cases, but not all.

Adult↗
PubMed1990

Accuracy of B-mode ultrasonography in detecting carotid plaque hemorrhage and ulceration.

A prospective study comparing the accuracy of B-mode ultrasound with evaluation of gross appearance in detecting plaque hemorrhage and ulceration is reported. Ultrasonography was performed on 78 vessels in 66 patients undergoing carotid endarterectomy. Carotid bifurcation atheroma were classified ultrasonographically as smooth, irregular, or ulcerated. Sonolucent areas were considered to be plaque hemorrhage. Analysis of carotid plaques removed at operation included macroscopic and microscopic findings. Duplex Doppler was only 44% sensitive but 78% specific for plaque hemorrhage. If all irregular atheroma were considered ulcerated, the sensitivity of Duplex Doppler was 81% with specificity only 33%. If only lesions with a clearly visualized crater were considered ulcerated, B-mode ultrasound was 85% specific but only 17% sensitive. False B-mode ultrasound diagnoses of ulceration were mainly due to culs-de-sac or pits in fibrotic plaque that looked like ulcers. Ulceration was not noticed on B-mode when there was a two-dimensional problem or calcification with shadowing. False B-mode diagnoses of plaque hemorrhage were due to atheromatous debris, ulcerated plaque hemorrhage, or calcification. Problems still exist in the B-mode ultrasound diagnosis of carotid plaque hemorrhage and ulceration.

Adult↗
PubMed1990

Routine exercise testing to detect coronary artery disease in patients with atherosclerotic vascular disease.

The ability of patients with peripheral vascular disease to perform exercise studies on a conventional treadmill is often hampered by claudication, amputation, ischemic ulceration or rest pain. This study was undertaken to investigate the use of the arm ergometer in these patients. Eighty-three patients admitted with peripheral vascular or carotid artery disease were subjected to electrocardiographic-monitored exercise testing, using both the arm ergometer and conventional treadmill, where possible. Coronary arteriography was performed consecutively on 32 of these patients to establish a control group from which the sensitivity, specificity and predictive accuracy of both methods of exercise testing could be calculated. Nineteen of the 70 arm ergometry tests and 22 of the 48 treadmill tests were positive. Nineteen of the patients with a positive test using either of the methods were asymptomatic for cardiac disease. All five patients who developed cardiac events during surgery had positive exercise tests, preoperatively. The sensitivity of arm ergometry in detecting coronary artery disease was 45.5% and the specificity 100%, while the figures for treadmill testing were 82.4% and 83.3%, respectively. The combined sensitivity for the two tests was 81.8% and the specificity 87.5%. Using a combination of these two tests thus provided a highly specific and adequately sensitive means of detecting the presence of coronary artery disease in patients presenting for peripheral vascular surgery.

Adult↗
PubMed1990

Pre-operative evaluation of palpable breast tumours.

The diagnostic accuracy of clinical examination, mammography and fine-needle aspiration cytology in identifying malignancy was retrospectively assessed in 207 women with palpable breast masses undergoing breast biopsy for histological examination. Clinical examination was more sensitive (96%) than mammography (81%) or cytology (69%). Cytological examination was totally specific for malignancy. The combined evaluation of clinical examination, mammography and cytological examination revealed a 100% diagnostic accuracy for concordant triplet results. Where discordant triplet results were recorded, 75% of tumours were malignant. Biopsy and frozen section are thus recommended if the 'triplet' provides conflicting results. Preliminary biopsy and frozen section may be unnecessary when the diagnostic triplet unequivocally demonstrates malignancy, or when cytological examination reliably reveals the presence of malignancy. Where the components of the triplet all point to benignity, the patient may be confidently followed up without the necessity of biopsy. The adoption of these guidelines may safely reduce the number of open breast biopsies by about 50-60%.

Adult↗
PubMed1990

The diagnosis of abdominal injuries in comatose patients.

The clinical course of 95 comatose trauma patients was prospectively evaluated. The role of clinical findings and diagnostic peritoneal lavage (DPL) combined with computed tomography (CT) were assessed in the diagnosis of abdominal injuries. Seven per cent of the patients were comatose due to hypoperfusion, and did not have a primary brain injury. Of the remaining 88 patients, 28% had an associated abdominal injury. Hypotension predicted an associated abdominal injury with an accuracy of 72%, and a haematocrit less than 30% had an accuracy of 82%. Clinical examination was 50% accurate. DPL was 93% accurate, with a false-positive rate of 10%. No abdominal injuries were present in the group in whom the lavage results were negative, while no unnecessary laparotomies were performed in the group with a 4+ or 5+ positive DPL (calorimetric method). In the group with 1+, 2+ and 3+ positive DPL, 3/15 laparotomies (12%) were done for minor abdominal injuries. Minimising unnecessary laparotomies was achieved by utilising CT to determine the nature and extent of the injury. By using DPL as a screening test, and CT to quantify the injury, unnecessary operations can be avoided, and all injuries can still be diagnosed.

Abdominal Injuries↗
PubMed1990

Incidence of extracranial injuries in fatal head injury patients.

The clinical notes of 148 patients who were admitted with head injuries and died were studied retrospectively and compared with the results of a postmortem examination. Risk factors predicting the presence of extracranial injuries were sought. Fourteen per cent of patients admitted with head injuries died. Two risk factors predicted the presence of extracranial injuries: 67% of the patients with an associated injury had been involved in a motor vehicle accident (MVA), compared with 32% of those with a head injury only. Shock was five times as common in the group with associated injuries than in those without. Associated injuries were present in 45% of patients, and 37% of these injuries were not diagnosed on admission. In 7% these injuries were the final cause of death. This study re-emphasises the fact that multi-organ trauma is common after MVA, and shock due to hypovolaemia is an unusual complication of head injury. Searching for associated injuries is mandatory in the head-injured patient. Since clinical examination is inaccurate, special investigations, such as peritoneal lavage or computed tomography, should be utilised for this purpose.

Adolescent↗
PubMed1990

The arm ergometer exercise test for evaluating coronary artery status in patients presenting for peripheral vascular surgery.

Various non-invasive methods exist for evaluating the cardiac status of patients presenting for peripheral vascular surgery. Methods involving exercise on a treadmill are frequently used, but adequate testing may be limited in amputees and patients with severe claudication or rest pain. An alternative means of exercise is the arm ergometer. A study of 130 patients subjected to arm ergometer exercise testing before peripheral vascular surgery was undertaken. A control group of 29 consecutive patients had coronary angiography. ECG exercise testing using the arm ergometer showed a sensitivity for detecting coronary artery disease of 46% and a specificity of 100%. In total, 42 tests were positive, 21 on patients with no symptoms of ischaemic heart disease and no resting ECG changes indicative of ischaemia, and 4 in patients with atypical angina. Muscle fatigue proved a problem, especially in women; while the accuracy of the test did not decline in patients over the age of 60 years when compared with those under this age.

Adult↗
PubMed1990

Primary echinococcus cyst of the thyroid. A case report.

Although echinococcosis is not rare in South Africa, the location of a hydatid cyst in the thyroid is unusual. It usually presents as a solitary nodule, which may mimic a thyroid carcinoma. The routine use of aspiration cytology in the workup of cases of single thyroid nodules may complicate the further management of patients with a hydatid cyst of the thyroid; anaphylaxis and dissemination may occur and technical difficulties may be experienced during operation. A case of echinococcal cyst of the thyroid presenting as a single thyroid nodule, suspected to be thyroid cancer, is reported.

Echinococcosis↗
PubMed1989

An electronic apparatus for early detection of changes in red cell content of blood during anaesthesia. A preliminary report.

An electronic apparatus was developed for anaesthetists to use to detect changes in red cell concentration during surgery. The mechanism is based on the relationship between the red cell content and the electrical conductivity of blood. In a pilot study of 170 blood samples, a correlation coefficient of 0.9806 was obtained between haematocrit and the instrument readings. To evaluate the instrument's performance in practice, and factors that might influence its readings, a series of 10 cases of aortic surgery were investigated. It is concluded that, although changes in electrolyte concentration, pH and temperature do affect the instrument's readings, these are insignificant compared with those of red cell content, and that the device can be used to indicate a drop in red cell concentration.

Anesthesiology↗
PubMed1988

Percutaneous transhepatic balloon dilatation of strictured hepaticojejunostomies.

Strictured hepaticojejunal anastomoses can be surgically repaired with excellent results. However, remedial surgery may be difficult or hazardous in some patients and percutaneous transhepatic balloon dilatation (PTHBD) may be used as an alternative. Three patients with complicated strictured hepaticojejunostomies have been managed with PTHBD with good short-term results. The procedure was safe, technically easy and associated with low morbidity. Although long-term efficacy is not proven, this method can be used to prepare patients for elective surgery or as a definitive procedure in patients who are poor surgical risks.

Adult↗