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Biomedical subjects

C Patel

Publications and source records attributed to C Patel.

At least 37 records · Page 2Linked to original sources

Determination of kanamycin concentration in serum by substrate-labeled fluorescent immunoassay.

A homogeneous substrate-labeled fluorescent immunoassay was developed for the measurement of kanamycin concentrations in serum. A fluorogenic drug reagent (FDR) (beta-galactosyl-umbelliferone-tobramycin) was prepared that is nonfluorescent under the conditions of the assay but is hydrolyzed upon catalysis by beta-galactosidase to yield a fluorescent product. Binding of the FDR to the antiserum to kanamycin prevented enzyme hydrolysis. The fixed level of FDR in the assay competed with kanamycin in the sample for a limited number of antibody-binding sites. Unbound FDR was hydrolyzed by beta-galactosidase to release a fluorescent product that is proportional to the kanamycin concentration in the sample. The assay exhibited good sensitivity, precision, and accuracy and correlated well with other methods.

Binding, Competitive

Trial of relaxation in reducing coronary risk: four year follow up.

On screening 192 men and women aged 35-64 were identified as having two or more of the following risk factors: blood pressure greater than or equal to 140/90 mm Hg, plasma cholesterol concentration greater than or equal to 6.3 mmol/l (243.6 mg/100 ml), and current smoking habit greater than or equal to 10 cigarettes a day. They were randomly allocated to a group for modification of behaviour or to serve as controls. Both groups were given health education leaflets containing advice to stop smoking, to reduce animal fats in the diet, and on the importance of reducing blood pressure. In addition, the treatment group had group sessions of one hour a week for eight weeks in which they were taught breathing exercises, relaxation, and meditation and about managing stress. It had previously been found that after eight weeks and eight months there was a significantly greater reduction in both systolic and diastolic blood pressures in the group taught to relax compared with the control group. After four years of follow up these differences in blood pressure were maintained. Plasma cholesterol concentration and the number of cigarettes smoked were lower in the treatment group at eight weeks and eight months but not at the four year follow up. At four years more subjects in the control group reported having had angina and treatment for hypertension and its complications. Incidence of ischaemic heart disease, fatal myocardial infarction, or electrocardiographic evidence of ischaemia was significantly greater in the control group. If the results of this study could be obtained in a larger study the financial and health care implications would be enormous.

Adult

Effect of oral alcohol on left ventricular ejection fraction, volumes, and segmental wall motion in normals and in patients with recent myocardial infarction.

A first-pass nuclear angiogram and a multiple-gated acquisition study were obtained in 10 normal physicians and in 10 patients with a 7-to-10 day old transmural myocardial infarction. After the scan the subjects drank 2 oz. of whiskey. After 60 minutes, the multiple-gated acquisition study was repeated. In the normal group the left ventricular ejection fraction was 68% before and 72% after alcohol. The left ventricular end-diastolic volume increased from 89 to 97 ml while the left ventricular end-systolic volume decreased from 29 to 27 ml. The stroke volume rose from 61 to 70 ml/beat (p less than 0.05). The cardiac output increased from 4.0 to 5.0 l/min (p less than 0.05). In the infarction group, the left ventricular ejection fraction was 58% before and 56% after alcohol administration. The left ventricular end-diastolic volume fell from 111 to 96 ml, while the left ventricular end-systolic volume declined from 50 to 44 ml. The stroke volume fell from 61 to 52 ml/beat, while the cardiac output fell from 4.5 to 3.8 l/min. In the left ventricular infarction zones, alcohol produced in 9 of the 10 cardiac patients a decline in the left ventricular regional ejection fraction. In the normal group, alcohol produced no significant changes in the regional ejection fraction. The normal and the postinfarction patients responded differently to alcohol.

Adult

An unusual case of X-15 translocation: evidence for the presence of an 'activator' region on Xpter of man.

A case of an X-autosome rearrangement is presented in which part of the Xpter is deleted but the STS and MIC2X loci are retained. The normal X is late replicating in 97/100 lymphocytes and 50/50 fibroblasts examined. It is assumed that the initial X-inactivation in the embryo is random, but that cells with the rearranged X inactivated are selected against because inactivation spreads into the attached autosomal segment. This spreading, through the normally active STS locus, is hypothesised to be caused by deletion of a part of Xpter which is critical for the maintenance of activity of the Xpter region as a whole.

Cells, Cultured

Pharmacology of propranolol in patients with cirrhosis and portal hypertension.

Ten patients with cirrhosis and protal hypertension received an initial 20 mg oral test dose of propranolol and subsequently 160 mg of a slow release preparation, orally, each day for seven days. Protein binding, serial plasma propranolol concentrations and effects on heart rate were studied. Protein binding was slightly reduced (mean 85%, range 78.9-88.1%) compared with four normals (mean 87.9%). In patients with severe liver disease (serum albumin less than 30 g/l) propranolol remained detectable in plasma 24 hours after the single 20 mg dose and high steady state concentrations (mean 266.5 ng/ml, range 84-406) were observed during regular dosing. At steady state there was a significant correlation between log total plasma propranolol concentrations and the percentage fall in heart rate (r = 0.659, p less than 0.05). We suggest that in patients with severe liver chronic disease (serum albumin less than 30 g/l), propranolol therapy should be initiated in hospital. The starting dose should be low (20 mg of the conventional formulation tds or 80 mg of the slow release preparation daily) and that regular monitoring of the heart rate should be carried out.

Aged

The value of screening for autoantibodies in patients with non-specific symptoms.

An autoantibody screen is often requested in patients with non-specific symptoms such as pyrexia of unknown origin. However, in a survey of 100 consecutive requests for this investigation in such patients only one patient was encountered in whom the investigation led to a positive diagnosis at an estimated cost of pound 2500. These requests accounted for 5% of the total workload. These observations reaffirm that this should remain a second line investigation and should be deferred until more likely diagnoses have been excluded.

Adolescent

Infectious endocarditis caused by Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans is a very uncommon cause of infectious endocarditis. The organism was first described in 1912. Thjotta and Sydnes reported its isolation in pure culture from a long standing abscess which had developed after tooth extraction. Subsequently this organism was found to be part of the normal flora, and the organism was defined as a slow growing, fastidious gram negative bacillus. Carbon dioxide is essential for the growth of A. actinomycetemcomitans. Approximately 50 cases of endocarditis due to A. actinomycetemcomitans have been reported since the first case reported in 1964. The purpose of this report is to document a case of endocarditis due to A. actinomycetemcomitans and to stress the value of the echocardiogram in the assessment of patients with endocarditis.

Actinobacillus

The Osborn wave in hypothermia.

A patient is reported who presented with fatal hypothermia. The electrocardiographic changes of a sinus bradycardia, prolonged QT interval and Osborn waves were documented and correlated with body temperature. The possible genesis of these electrocardiographic changes is reviewed in this article.

Bradycardia

Immunology of inflammatory bowel disease.

Although the aetiology of ulcerative colitis and Crohn's disease remain unknown, immunological effector mechanisms become activated within the inflamed mucosa and may be responsible for the pathogenesis of chronic disease. There is an increased production of immunoglobulin within the mucosa, some of which has specificity for bacterial antigens, and complement activation occurs during exacerbation of the disease. Lymphocytes isolated from peripheral blood, or from the intestinal mucosa, are cytotoxic to colonic epithelial cells in vitro; a reaction which can be modulated by serum factors and bacterial antigens. Within the mucosa, there are increased populations of T lymphocytes although there is no change in the ratio of helper- to suppressor-cells as defined by phenotype. Studies of immunoregulatory control have shown that there may be alterations in the modulation of the local immune response, especially during active disease, although it is not clear whether these changes are primary or merely secondary to inflammation. It is posulated that many of the humoral and cellular responses to gut-associated antigens occur as a result of increased antigen absorption, increased presentation of antigen to the immune system due to the expression of Class II antigens by the inflamed epithelium and altered immuno-regulatory control.

Antigen-Antibody Complex

Value of radionuclide angiogram for the diagnosis of Ebstein's anomaly.

A radionuclide angiogram in a patient with Ebstein's anomaly showed a very dilated right atrium with a minimally enlarged right ventricle and a normal sized left ventricle. This study led to the establishment of a definitive diagnosis by means of an echocardiogram. Late close of the tricuspid valve was demonstrated. In addition prolapse of the tricuspid and mitral valves was documented. A tricuspid valve prolapse has never been reported in this condition.

Blood Pressure

Upper gastrointestinal endoscopy in systemic vasculitis presenting as an acute abdomen.

Three cases of upper gastrointestinal vasculitis presenting as acute abdominal emergencies highlight an uncommon but often fatal presentation of systemic vasculitis. Although abdominal symptoms are common in such diseases, there may be a doubt during assessment of the patient as to whether the gastrointestinal tract is the prime target organ. Radiology is often negative during the acute illness. Endoscopy was important in documenting early and more advanced bleeding lesions of polyarteritis nodosa (PAN) and Henoch-Schoenlein disease, both conditions in which upper gastrointestinal lesions are rare. The gastric and duodenal vasculitic lesions demonstrated by endoscopy in such a clinical setting were confirmed histologically. Endoscopic assessment and early aggressive medical therapy contributed significantly towards the overall successful outcome. Gastroduodenoscopy has not been used either routinely or as an emergency investigation for the assessment of patients with vasculitis who present with acute abdominal pain. Involvement of the stomach and duodenum by vasculitis is therefore poorly appreciated, but remains a serious complication of vasculitic disease when the gastrointestinal tract is the prime target organ, and the information gained by endoscopy in a difficult clinical situation might alter the overall outcome of the disease.

Abdomen, Acute

Nucleoli, micronucleoli, and nucleolus-like structures in human oocytes at meiotic prophase I studied by the silver-NOR technique.

Meiotic nuclei preparations obtained from human fetal ovaries were studied with the silver-NOR technique. At leptotene, the NOR's were located at the periphery of the nucleoli. The mean number of NOR's per nucleus was 6.4. Moreover, 2-12 micronucleoli, each containing an Ag-positive zone, were observed. At pachytene, each nucleolus was divided into two zones, one of which was Ag-positive. The mean number of Ag-positive zones was 2.1 per nucleus. The subterminal region of the short arm of nucleolar bivalents was in contact with the argyrophilic nucleolar zone. In most cells, micronucleoli were dispersed between the bivalents. A single rounded body which stained heavily with silver was consistently observed. At early diplotene, the NOR's separated, appearing again as distinct rounded Ag-positive structures embedded in the peripheral part of the nucleoli. The silver-stained round body was still visible. Eight to twelve micronucleoli were observed. At a more advanced stage of diplotene, the number of micronucleoli increased, varying from 20 to 50 per nucleus. These observations suggest that the micronucleoli, already visible at the leptotene stage, are the morphological expression of an early transcription of amplified rDNA. The biological significance of the Ag-positive round body remains obscure, but the consistency of its appearance suggests that it has a specific function somehow related to nucleolar proteins.

Cell Nucleolus