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Biomedical subjects

J Brown

Publications and source records attributed to J Brown.

At least 757 records · Page 42Linked to original sources
PubMed1989

Parathyroid adenocarcinoma.

Parathyroid adenocarcinoma is a very rare carcinoma with an equal male-female incidence. The clinical picture that adenocarcinoma of the parathyroid presents is the same as that of hyperparathyroidism due to adenoma. Onset of parathyroid adenocarcinoma occurs primarily in the fourth decade of life. It is not incompatible with long-term survival provided that the entire gland is removed at the initial operation without rupture of the capsule. If the carcinoma recurs, it grows slowly and any spread tends to be local. Distant metastasis is rare. Calcium levels above 13 mg/100 mL should alert the clinician to the possibility of adenocarcinoma of the parathyroid. Increased mitotic figures, increased fibrosis of the gland, and invasion of the vessels and surrounding tissues are the features indicative of malignancy. A review of the literature reveals that fewer than 150 cases of this entity have been reported. The authors present two case reports and discuss the epidemiology, clinical picture, pathology, and therapy of parathyroid adenocarcinoma.

Adenocarcinoma↗
PubMed1989

Transrectal ultrasonography of the cranial mesenteric artery of the horse.

Transrectal ultrasonography was performed on the cranial mesenteric artery and its major branches in 23 conscious adult horses. Ultrasonographically, 25 arterial segments were classified as either normal or abnormal. These ultrasonographic classifications were later compared with the gross and histologic evaluations of each artery following necropsy of each horse. In this study, transrectal ultrasonography as a diagnostic test for verminous arteritis had a 90% sensitivity for detecting normal arteries and an 86% specificity for detecting abnormal arteries, suggesting that ultrasonography may be useful in the antemortem diagnosis of verminous arteritis.

Animals↗
PubMed1989

In vitro ultrasonographic appearance of the normal and verminous equine aorta, cranial mesenteric artery, and its branches.

Ninety-one equine aortic and cranial mesenteric arterial segments were evaluated ultrasonographically in a water bath. On the basis of pathologic evidence of verminous arteritis, arterial segments were classified into 4 categories, and the ultrasonographic characteristics of each group were evaluated. Normal arteries (class 1) were ultrasonographically characterized by a smooth luminal surface layer and uniform wall thickness and echogenicity. Arteries with only histopathologic evidence of verminous arteritis (class 2) were ultrasonographically characterized by a smooth luminal surface layer, uniform hyperechoic luminal layer. Arteries with both gross and histopathologic evidence of verminous arteritis (class 3) were characterized ultrasonographically by an irregular luminal surface layer, varying wall thickness, varying wall echogenicity, and the presence of a hyperechoic luminal layer. The ultrasonographic characteristics of arteries with luminal thrombosis (class 4) were an irregular luminal surface, varying wall thickness, and nonuniform echogenicity.

Animals↗
PubMed1989

Prolonged dietary protein restriction in diabetic nephropathy.

Eleven patients with insulin-dependent diabetes, advancing renal insufficiency, and proteinuria were placed on a diet containing 0.6 g/kg per day of high-biologic-value protein. Selected clinical variables were observed over a 2-year interval. The rate of decline in renal function was significantly decreased during the intervals of protein restriction. The rate during the second 12 months of the study, however, was increased, when compared with the first 12-month interval. Urinary protein excretion decreased significantly, from 2.27 +/- 0.49 g/d to 0.57 +/- 0.40 g/d after the first 12 months of the study, but increased to 1.43 +/- 0.63 g/d after the second 12 months of the study. The dietary protein intake estimated from urea nitrogen excretion in urine samples correlated significantly with urinary protein excretion. These findings suggest that dietary protein restriction has a sustained beneficial effect on the course of diabetic nephropathy, if compliance to the diet can be maintained.

Adult↗
PubMed1989

Vision screening of school age children in Missouri.

In this report, vision screenings conducted by schools in the state of Missouri are reviewed. Data were generated by the 127 participating schools in 38 school districts that responded to four research questions. In general, many inadequacies exist in schools regarding vision screening. Recommendations include greater participation in the public school arena by vision specialists and the development of consistent criteria for vision screening in school districts.

Adolescent↗
PubMed1989

Optimal hypothermic preservation of arrested myocardium in isolated perfused rabbit hearts: a 31P NMR study.

The purpose of this study was to (1) relate myocardial high-energy phosphate stores to functional recovery after ischemia and reperfusion, (2) assess the bioenergetics and functional influence of clinically relevant myocardial hypothermia, and (3) examine tissue pH as an independent indicator of postischemic recovery of function. Rabbit hearts were perfused via a modified Langendorff technique, monitored for developed pressure (DP) and left ventricular end-diastolic pressure (LVEDP) via an isovolumic left ventricular balloon catheter, and placed in a Brucker NMR magnet (4.7 tesla) to measure phosphocreatine (PCr), adenosine triphosphate (ATP), and pH. Hearts underwent 1 hour of global ischemia at 7 degrees, 17 degrees, 27 degrees and 37 degrees C initiated by one dose of K+ cardioplegia followed by 30 minutes of reperfusion. After reperfusion, DP (expressed as a percentage of preischemic control) and LVEDP (mm Hg) in 7 degrees and 17 degrees C hearts were no different (96 + 5% vs 97 +/- 3%; 5 +/- 2 mm Hg vs 6 +/- 2 mm Hg; p = NS), but were better (p less than 0.01) than 27 degree hearts (72 +/- 6%, 17 +/- 6 mm Hg) and 37 degree hearts (31 +/- 7%, 60 +/- 6 mm Hg). PCr was severely depleted in all groups. ATP was 90 +/- 7% and 87 +/- 5% of preischemic control in the 7 degree and 17 degree hearts, which was significantly better than the 68 +/- 3% and 21 +/- 3% in the 27 degree and 37 degree groups (p less than 0.01). The pH at end ischemia was 6.83, 6.89, 6.54, and 5.86 for the 7 degree, 17 degree, 27 degree, and 37 degree hearts, respectively (7 degrees vs 27 degrees or 37 degrees, p less than 0.01; 17 degrees vs 27 degrees or 37 degrees, p less than 0.01). Linear regression of DP on end-ischemic ATP (EIATP) and end-ischemic pH revealed: DP = 0.96 (EIATP) + 20 (r = 0.92) and DP = 60 (pH) -317 (r = 0.86). We conclude that (1) end-ischemic ATP predicts recovery of ventricular function, and, furthermore, there appears a threshold ATP concentration (80% of control) below which full recovery of function will not occur; (2) end-ischemic pH predicts recovery of ventricular function; (3) 7 degrees C hypothermic ischemia does not cause a clinically significant cold injury; and (4) in a single-dose crystalloid cardioplegia model, end-ischemic pH is linearly related to recovery of function (r = 0.86).

Adenosine Triphosphate↗
PubMed1988

Chloroquine treatment of severe malaria in children. Pharmacokinetics, toxicity, and new dosage recommendations.

Although empirical regimens of parenteral chloroquine have been used extensively to treat severe malaria for 40 years, recent recommendations state that parenteral chloroquine should no longer be used because of potential toxicity. We studied prospectively the pharmacokinetics and toxicity of seven chloroquine regimens in 58 Gambian children with severe chloroquine-sensitive falciparum malaria. In all regimens the total cumulative dose was 25 mg of chloroquine base per kilogram of body weight. Chloroquine was rapidly absorbed after either intramuscular or subcutaneous administration (5 mg of base per kilogram every 12 hours), producing high peak blood concentrations but transient hypotension in 5 of 18 patients (28 percent). Intermittent intravenous infusion (5 mg of base per kilogram over 4 hours, repeated every 12 hours) also produced wide fluctuations in chloroquine levels, suggesting incomplete distribution from a small central compartment. Continuous infusion (0.83 mg of base per kilogram per hour for 30 hours) and smaller, more frequent intramuscular or subcutaneous injections of chloroquine (3.5 mg of base per kilogram every 6 hours) produced smoother blood-concentration profiles with lower early peak levels and no adverse cardiovascular or neurologic effects. Chloroquine given by nasogastric tube (initial dose, 10 mg of base per kilogram) was absorbed well, even in comatose children. We conclude that simple alterations in dosage and frequency of administration can give parenteral chloroquine an acceptable therapeutic ratio and reinstate it as the treatment of choice for severe malaria in areas where chloroquine resistance is not a major problem.

Animals↗
PubMed1988

Development of a solid-phase extraction technique for alpha-human atrial natriuretic peptide in human plasma.

A reliable extraction method was developed for alpha-human atrial natriuretic peptide (alpha-hANP) using Bond Elut C8 columns in tandem. This involved activation of the columns using methanol followed by a water wash to remove the excess methanol. Plasma (1 ml) was then added and a vacuum applied until all was drawn through. Excess protein and other endogenous compounds were removed by washing the columns with water and elution of the alpha-hANP was achieved with 0.75 ml acetonitrile-water-trifluoroacetic acid (80:19.8:0.2, v/v/v). Samples were evaporated under nitrogen and reconstituted in radioimmunoassay buffer ready for analysis. The recovery of alpha-hANP from plasma using this method was found to be 90% +/- 0.6% [mean +/- standard error of the mean (S.E.M.); coefficient of variation (C.V.) = 1.5%] which will allow more precise measurement of the peptide than is presently available. With this high precision of analysis available, having a limit of detection of 0.4 fmol/ml and a range of 0 to 32 fmol/ml, a low-dose infusion of alpha-hANP was conducted and the changes in plasma concentration were followed.

Atrial Natriuretic Factor↗
PubMed1988

A subpopulation of dopaminergic neurons in rat ventral mesencephalon contains both neurotensin and cholecystokinin.

The coexistence of the neuropeptides neurotensin and cholecystokinin and the catecholamine-synthesizing enzyme tyrosine hydroxylase within neurons of the ventral mesencephalon was analyzed using an immunofluorescence triple-labeling technique. Virtually all of the neurotensin-positive cell bodies in the ventral tegmental area, medial substantia nigra pars compacta, retrorubral field, and rostral and caudal linear raphe nuclei were found to contain both cholecystokinin and tyrosine hydroxylase immunoreactivities. The degree of colocalization was lower and more variable in other regions including the ventral and central periaqueductal grey matter and dorsal raphe nucleus. It appeared that immunoreactivities for these 3 neuroactive substances were not contained within the same axonal-like fibers and terminals in the ventral midbrain. These results demonstrate that a subpopulation of dopaminergic neurons, which presumably comprise part of the ascending mesotelencephalic system, contains the two peptides neurotensin and cholecystokinin. Thus, the data suggest a morphological basis for some of the reported functional interactions of these 3 putative neurotransmitters/neuromodulators within this system.

Animals↗
PubMed1988

Antagonism of V2-receptor effect of antidiuretic hormone by atrial natriuretic peptide in man.

Human alpha-atrial natriuretic peptide (h-alpha ANP) makes the urine of dehydrated volunteers hypotonic to plasma despite high circulating concentrations of antidiuretic hormone. Urinary dilution with h-alpha ANP also occurs in subjects receiving indomethacin. Therefore, h-alpha ANP antagonises effects of antidiuretic hormone on distal tubular V2-receptors in man, probably without involving prostaglandins.

Arginine Vasopressin↗
PubMed1988

Electrocardiographic criteria for ventricular tachycardia in wide complex left bundle branch block morphology tachycardias.

Four electrocardiographic criteria for ventricular tachycardia (VT) were proposed and evaluated. These included (1) an R wave in V1 or V2 of greater than 30-ms duration; (2) any Q wave in V6; (3) a duration of greater than 60 ms from the onset of the QRS to the nadir of the S wave in V1 or V2 and (4) notching on the downstroke of the S wave in V1 or V2. The data showed that all 4 criteria had high predictive accuracy (96 to 100%) and specificity (94 to 100%). The relatively low sensitivities of the 4 criteria alone (30 to 64%) might limit their efficacy. Grouped criteria, however, could differentiate VT from supraventricular tachycardias with high sensitivity, specificity and predictive accuracy. The amount of tracings having either electrocardiographic criteria (1) or (2) or (3) or (4) was determined. The proposed combined criteria had a sensitivity of 100%, specificity of 89% and a predictive accuracy of 96%. Left axis deviation alone was of no value in distinguishing VT from supraventricular tachycardia. Characteristic patterns were present for left bundle branch block pattern VT associated with anterior and inferior myocardial infarction. In conclusion, the 12-lead electrocardiogram alone, when systematically analyzed, can be used to accurately diagnose the origin of wide complex tachycardias with left bundle branch block pattern. Attention to these criteria may lead to more rapid and effective therapy.

Bundle-Branch Block↗
PubMed1988

The effects of intravenous L-dopa on plasma renin activity, renal function, and blood pressure in man.

L-dopa 7 micrograms.kg-1.min-1 was given intravenously over 2 h to six healthy subjects, controlled by an infusion of saline on a separate occasion, with measurement of plasma renin activity (PRA), urinary sodium and potassium excretion, effective renal plasma flow (ERPF), glomerular filtration rate (GFR), blood pressure, and pulse rate. Mean PRA fell by 50% following L-dopa, which was significantly different from the slight rise which occurred after saline infusion. There was a significant increase in urinary sodium excretion and effective renal plasma flow on infusion of L-dopa. Mean diastolic blood pressure fell during L-dopa infusion, in contrast to the slight increase which occurred during the control study. These observations confirm the anticipated renal dopaminergic effects of L-dopa and also suggest a dopaminergic influence on renin release in man.

Adult↗
PubMed1988

Plasmodium falciparum: the behavior of clinical isolates in an in vitro model of infected red blood cell sequestration.

An in vitro model of Plasmodium falciparum-infected red blood cell sequestration which uses C32 amelanotic melanoma cells as targets has been used to examine the binding capacity of infected red blood cells from subjects with naturally acquired P. falciparum infections of varying severity. The binding of infected red blood cells (IRBCs) to melanoma cells was specific to cells containing mature parasites. Variations in target cell density and in conditions of growth had significant effects on binding. Binding was pH dependent, being maximum at a pH of 6.9. Using standardized conditions the binding capacity of individual isolates of P. falciparum could be measured with a high degree of reproducibility. Binding capacity of IRBCs from 51 subjects between the ages of 6 months and 15 years varied between 12 and 1254 IRBCs per 100 melanoma cells when RBC suspensions at a 1% parasitemia and 4% hematocrit were used. Variation in binding was not related to the level of peripheral parasitemia of the isolate or to differences in adaptation to culture conditions. The binding capacity of parasitized cells from subjects with cerebral malaria did not differ from that of IRBCs from subjects with less serious clinical manifestations.

Adolescent↗
PubMed1988

Factors influencing compliance with dietary restrictions in dialysis patients.

Dietary restrictions for dialysis patients are very demanding and compliance has been shown to be poor in many patients. A number of psychosocial variables were investigated in a sample of 41 dialysis patients for possible effects on dietary compliance. Clinical criteria of dietary abuse indicated problems in 58% of the sample. Self reported compliance was significantly associated with clinical abuse scores. The longer patients had been on dialysis, the less likely they were to report dietary compliance. Health locus of control and family support were significantly associated with specific items of self reported compliance, but not with overall compliance scores. Acceptance of the limitations imposed by illness was significantly associated with clinical dietary abuse scores. The process whereby positive adjustment and good dietary control may be achieved, is discussed.

Feeding Behavior↗
PubMed1988

Trisomy 4 in acute nonlymphocytic leukemia. An Australian case.

We report a case of acute nonlymphocytic leukemia, type M4 according to the FAB classification, whose cytogenetics showed trisomy 4 and multiple double minute chromosomes. The patient gave no history of exposure to toxic or carcinogenic substances.

Acute Disease↗