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Biomedical subjects

J Brown

Publications and source records attributed to J Brown.

At least 883 records · Page 49Linked to original sources
PubMed1985

Sequential technetium-99m/gallium-67 scintigraphic evaluation of subclinical osteomyelitis complicating fracture nonunion.

Twenty-four patients with a history of post-traumatic fracture nonunion underwent sequential 99mTc and 67Ga citrate scintigraphy in an attempt to differentiate between posttraumatic fracture nonunion and nonunion complicated by subclinical osteomyelitis. Neither technetium nor gallium studies alone nor in combination, with or without clinical correlation, could help delineate between fracture nonunion and nonunion complicated by subclinical osteomyelitis because of the increased technetium and gallium radioisotope uptake associated with the nonunion site.

Adolescent↗
PubMed1985

Ventricular function in transposition of the great arteries: evaluation by radionuclide angiocardiography.

Right ventricular ejection fraction and tricuspid regurgitation were estimated by radionuclide angiocardiography to quantitate systemic ventricular function in "simple" transposition of the great arteries. Mean right ventricular ejection fraction was 0.52 +/- 0.07 for 18 pre Mustard operation infants, 0.54 +/- 0.07 for 23 patients operated upon less than a 1 year before, and 0.57 +/- 0.08 for 14 patients operated upon more than 3 years earlier. Eight patients were evaluated before and following the Mustard operation; ejection fraction rose in three, fell in three, and remained constant in two. Mean right ventricular ejection fraction was not different between groups nor when compared to our "normal." The left ventricle:right ventricle stroke volume ratio of the postoperative patients was compatible with tricuspid regurgitation in four patients. This radionuclide study suggests that following surgery for transposition of the great arteries: mean right ventricular systolic ejection fraction remains at levels consistent with values usually found for the "normal" right ventricle; group right ventricular function does not deteriorate in the years following surgery; and tricuspid regurgitation may be detected in the early postoperative years.

Aging↗
PubMed1985

Psychological normality and abnormality in persistent headache patients.

One hundred and three patients referred to a neurological outpatient clinic were examined to assess the relationship between persistent headache, not due to significant physical illness, and emotional disturbance. Overall, the patients showed slightly more evidence of emotional disturbance than a general practice population but less than psychiatric outpatients. Thus, with cut-off points of 4/5 and 9/10 on the General Health Questionnaire (GHQ 28) the whole group had 52% or 20% of psychiatric 'cases' respectively. On the Crown-Crisp Experiential Index the 70 females had mean total scores of 37.19 +/- 11.11 and the 33 males had scores of 31.79 +/- 11.36. In addition the childhood experiences measured by the Parental Bonding Instrument appeared to be normal. Seven patients had significant depressive illness, according to the Levine-Pilowsky Depression Questionnaire. Statistically significant differences in psychological state did not emerge between the diagnoses of cluster headache, classical migraine, common migraine, tension headache or combined headache. However, negative correlations were found between the duration of illness and measures of anxiety. It is concluded that although the emotional state contributes to the development of pain and headache in some patients, there are others in whom comparable headaches are unlikely to be due to emotional factors. Selection effects are held to be important and some of the emotional changes will vary at different phases of a chronic disorder. A new symptom may initially cause anxiety but when a condition persists some patients will be increasingly concerned or depressed whilst others develop tolerance for the situation.

Adolescent↗
PubMed1985

Surgery for discrete subvalvular aortic stenosis: actuarial survival, hemodynamic results, and acquired aortic regurgitation.

Discrete membranous subaortic stenosis (DMSS) accounts for 8 to 30% of congenital left ventricular outflow obstruction. The immediate effectiveness of surgical resection of this discrete obstructing membrane has been well documented, but little has appeared regarding late clinical and hemodynamic follow-up. Fifty-three patients with DMSS underwent operation at our institution from 1957 to 1983. Most (78%) were symptomatic, 79% had left ventricular hypertrophy (LVH) by electrocardiogram, and 92% had roentgenographic evidence of cardiomegaly preoperatively. Catheterization revealed a mean preoperative left ventricular-aortic gradient of 89 mm Hg. Twenty-eight patients had associated aortic insufficiency (AI) on the initial aortogram. Seven patients acquired AI in the interim between the first and second preoperative catheterization. Our patients have been followed for up to 12 years postoperatively. There have been 2 early and 3 late deaths. (Actuarial analysis revealed 5- and 10-year survival of 95% and 83%, respectively.) Seventy-one percent of the previously symptomatic patients noted relief of their preoperative complaints, and 45% of those with LVH had a regression in voltage. Cardiomegaly as determined by chest roentgenogram decreased in 45%. The left ventricular-aortic gradient fell to an average of 35 mm Hg a year postoperatively. Surgical treatment of congenital subvalvular aortic stenosis is effective in reducing the preoperative symptoms and the left ventricular-aortic gradient. It appears that DMSS causes AI.

Actuarial Analysis↗
PubMed1985

gamma-L-Glutamyl-L-dopa is a dopamine pro-drug, relatively specific for the kidney in normal subjects.

gamma-L-Glutamyl-L-dopa was given by intravenous infusion to eight normal subjects at doses of 12.5 and 100 micrograms min-1 kg-1. Both doses of the dipeptide resulted in an increase in mean urinary sodium excretion. Mean effective renal plasma flow rose at both doses, but mean glomerular filtration rate increased only at the lower dose. There was a fall in mean plasma renin activity after the infusion of both 12.5 and 100 micrograms min-1 kg-1. Mean urine free dopamine excretion increased by 280- and 2500-fold at infusion rates of 12.5 and 100 micrograms min-1 kg-1 respectively. Mean plasma free dopamine rose at both doses but the increase at 12.5 micrograms min-1 kg-1 was not to a level previously associated with systemic effects of the catecholamine. On administration of the dipeptide at 12.5 micrograms min-1 kg-1 there were no changes in blood pressure or heart rate, but at the higher dose there was a fall in diastolic blood pressure. At a dose of 12.5 micrograms min-1 kg-1 in man, there is kidney specific conversion of gludopa to dopamine.

Adult↗
PubMed1985

Effects of continuous alpha (1-24) ACTH infusion in the dog.

Dogs chronically infused with alpha (1-24) ACTH for 2 weeks showed continuous elevations in plasma ACTH, cortisol, and progesterone levels. Haematologic changes included immediate increases in numbers of mature neutrophils and monocytes and reduced numbers of eosinophils and lymphocytes. Haematocrits were also reduced with ACTH infusion. Whereas serum potassium levels fell in association with ACTH, serum sodium was unchanged. Activities of two serum enzymes of probable liver origin, alkaline phosphatase and alanine aminotransferase, increased gradually with ACTH treatment. Histologic examination of liver tissue revealed prominent hepatocellular vacuolisation. The trophic action of ACTH infusion was manifested by an increased adrenal gland weight and an enhanced cortisol response to a bolus ACTH injection given 1 day after the infusion ceased. Long-term infusion of ACTH resulted in haematologic, biochemical and morphologic changes resembling those observed in dogs with spontaneous pituitary-dependent hyperadrenocorticism.

Adrenocorticotropic Hormone↗
PubMed1985

The effect of oral fenoldopam (SKF 82526-J), a peripheral dopamine receptor agonist, on blood pressure and renal function in normal man.

The effect of a single oral dose of 100 mg of fenoldopam on renal function and blood pressure was investigated in seven healthy male subjects in a double-blind placebo controlled study. Mean diastolic blood pressure fell by 10 mm Hg, 45 min after oral dosing and then gradually returned to baseline values. There was an increase in pulse rate and a delayed rise in systolic blood pressure. Measured from 30 to 120 min after drug ingestion, mean effective renal plasma flow increased to 158% of the value observed after placebo; mean glomerular filtration rate rose to 109% of the placebo value. Measured from 120 to 210 min after administration of the drug, effective renal plasma flow and glomerular filtration rate had returned to baseline values. Fenoldopam produced a small increase in the mean sodium excretion rate which was not significantly different from the fall after placebo. No change was detected in urine flow or potassium excretion rate. Mean plasma renin activity increased three-fold 1 h after oral dosing. Plasma aldosterone did not show a parallel increase although the plasma concentration at 1 h was significantly higher than after placebo. The results show a pronounced renal vasodilator effect lasting about 2 h. The findings are consistent with marked DA1 receptor agonist activity.

Administration, Oral↗
PubMed1985

Cellular and humoral inhibition of Plasmodium falciparum growth in vitro and recovery from acute malaria.

Both mononuclear cell cytotoxicity and serum inhibition of Plasmodium falciparum growth in vitro were found to vary according to the stage of infection in Gambian children with clinical malaria. Cytotoxicity was displayed by mononuclear cells and serum from children with acute malaria but this form of parasite killing was more effective in children with low grade P. falciparum infections of at least 10 days duration. Parasite inhibitory antibody was not evident in sera from acutely infected children but was found in sera from children recovering from malaria and reached a peak in convalescent children when P. falciparum growth was inhibited by at least 50%. The humoral response in convalescent children was strain related, being more effective against the most recent infecting parasite strain than against other 'wild' P. falciparum isolates. In contrast, mononuclear cell cytotoxicity was not strain related; when effective, multiplication of all parasite isolates tested was retarded to the same degree. The discussion considers the role of mononuclear cell cytotoxicity in the development of protective immunity and suggests that it may be a 'front line' defense mechanism during each malaria attack.

Adolescent↗
PubMed1985

Effects of selective channel blocking agents on contractions and action potentials in K+-depolarized guinea-pig atria.

Contractions and transmembrane action potentials were induced by 1 microM isoprenaline in K+-depolarized guinea-pig left atria driven at 0.5 Hz. The stability of these responses was significantly increased by doubling the extracellular glucose concentration to 22 mM. Action potential overshoot increased by 28 mV per ten fold increase in extracellular calcium concentration suggesting that the inward current in this preparation is carried by Ca2+. In depolarized driven preparations, nanomolar concentrations of nifedipine and nisoldipine reduced contractility, maximum rate of depolarization (dV/dt max) and action potential height, whereas the fast channel blocking agents tetrodotoxin and mexiletine (in micromolar concentrations) produced little change. Nifedipine also rendered spontaneously beating depolarized right atrial preparations quiescent. In concentrations which reduced dV/dt of normal action potentials, the sodium channel blocking agents quinidine and Org 6001 reduced the amplitude of contractions and reduced the maximum rate of phase 0 depolarization (dV/dt) of action potentials in depolarized tissue. These actions were reversed by Ca2+ and suggest calcium antagonistic activity. However action potential height was not reduced. Like bepridil, both drugs also reduced the frequency of spontaneous contractions in depolarized right atrial preparations. Unlike Org 6001, quinidine failed to produce a shift in calcium log dose-response curves in driven depolarized preparations and induced positive inotropy in the presence of functional sodium channels. Bepridil inhibited contractions in depolarized atria in the absence of a reduction in dV/dt suggesting that any calcium antagonistic action in atrial tissue is mainly located at an intracellular site. In conclusion, action potentials elicited by isoprenaline in potassium-depolarized atria bathed in high glucose appear to be Ca2+ mediated. In concentrations which inhibit the inward Na+ current, both quinidine and Org 6001 exhibit calcium channel blocking properties.

Action Potentials↗
PubMed1985

Antiepileptic and antiamnesic effect of carbamazepine in experimental limbic epilepsy.

Carbamazepine (20 mg/kg, 40 mg/kg or 60 mg/kg) given three times a day, has been demonstrated to have a significant anti-epileptic effect in rats with chronic limbic epilepsy induced by injecting tetanus toxin bilaterally into their hippocampi. This effect involved a reduction in the maximum number of fits occurring on one day, and with the highest dose, a significant reduction in the total number of fits. In a pilot experiment in which continuous EEG records were obtained throughout the syndrome, it appeared that the effect of carbamazepine was to reduce the proportion of EEG seizure discharges which lead to overt motor fits. With the higher drug dose plasma levels of carbamazepine were maintained around 2 micrograms/ml. This experimental epilepsy produces enduring deficits in the rats' memories for a light-discrimination task in a Y-maze learned before induction of epilepsy (8 weeks after initial learning). If the rats are dosed with carbamazepine during their epilepsy this memory deficit is abolished.

Amnesia↗
PubMed1985

The effect of aflatoxin on complement activity in broiler chickens.

Groups of broiler chickens were fed rations containing .625, 1.25, or 2.5 micrograms total aflatoxin/g of feed from one day to 42 days of age. Treatment groups were segregated according to sex and control groups were maintained. The chickens were bled at 14-day intervals, and serum was collected for assay of total complement (C) activity using a radial hemolytic procedure. No significant differences were found in C titers between males and females of the same age group. For the sexes combined, mean C titers of chickens fed aflatoxin were compared to mean titers of controls. For each age group, significant differences in C titers existed only between the control group and those chickens fed 2.5 micrograms/g aflatoxin. Complement is a major component of the humoral immune response and this study adds to the evidence that aflatoxin can be immunosuppressive to chickens.

Aflatoxins↗
PubMed1985

Patients with essential hypertension have an exaggerated natriuretic response to the dopamine pro-drug glutamyl-dopa.

The relatively kidney-specific dopamine pro-drug, gamma-L-glutamyl-L-dopa (gludopa) was administered to eight normal subjects and eight patients with essential hypertension, control studies being provided by the infusion of saline on a separate occasion. There was a more marked natriuresis in the hypertensives than in the normal subjects, even though, in contrast to the normals, the hypertensives showed no significant change in effective renal plasma flow (ERPF) or glomerular filtration rate (GFR). A significant fall in plasma renin activity (PRA) occurred in both groups. These observations suggest that a part of the dopamine-induced natriuresis is due to stimulation of tubular receptors, and that there is up-regulation of these receptors in essential hypertension.

Adult↗
PubMed1985

Reversal of thiopental-induced anesthesia by 4-aminopyridine, yohimbine, and doxapram in dogs pretreated with xylazine or acepromazine.

Groups of atropinized dogs (6 dogs/group) were sedated, using xylazine HCl (2.2 mg/kg of body weight, IM) or acepromazine maleate (0.25 mg/kg, IM), and were anesthetized to loss of pedal reflexes, using thiopental, IV. The dogs were given 1 of the following test antagonists, IV: saline solution (2 ml; control group), 4-aminopyridine (4-AP; 0.5 mg/kg), yohimbine (0.4 mg/kg), doxapram (5.0 mg/kg), or dual combinations of the latter 3 substances in the same doses as used for each agent. In xylazine-treated dogs, the mean dosage of thiopental required to induce anesthesia was 4.8 mg/kg. Control mean arousal time (MAT) and walk time (MWT) were 37.1 minutes and 53.8 minutes, respectively. These values were decreased to less than 2 minutes and less than 3 minutes, respectively, by yohimbine, 4-AP + yohimbine, and doxapram + yohimbine. With doxapram and with 4-AP + doxapram, MAT was less than 2 minutes and MWT was less than 8 minutes. In acepromazine-treated dogs, the mean dosage of thiopental required for anesthesia was 15.0 mg/kg. Control MAT and MWT were 20.7 minutes and 36.5 minutes, respectively. These values were decreased to 8.1 minutes and 18.1 minutes, respectively, by doxapram, and to 3.5 minutes and 19.9 minutes, respectively, by doxapram + yohimbine. Doxapram, 4-AP + doxapram, and doxapram + yohimbine caused periodic extensor rigidity before and during arousal. This rigidity was accompanied by opisthotonos in 2 dogs of the doxapram + yohimbine group and may have been mild tonic seizures.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1985

Changes in antithrombin, antiplasmin, and plasminogen during and after cardiopulmonary bypass.

Platelet counts and several clotting parameters, especially antithrombin, alpha 2-antiplasmin, and plasminogen, were determined in 33 patients undergoing cardiopulmonary bypass surgery. Except for Factors VIII and XI, all activities measured fell significantly as the patients were placed on the pump. This initial drop paralleled the drop in hematocrit, i.e., the drop was most likely due to hemodilution. During the entire procedure the activities remained decreased, again paralleling the hematocrit. Only the drop in platelet counts was greater than the hematocrit, suggesting additional consumption during bypass. In the ICU a second significant drop in antithrombin, prothrombin, and Factor V was noted that was not reflected by a drop in hematocrit. The cause for this is not known at this time. Although the patients with the lowest antithrombin levels, compared to the highest levels in the ICU seemed to have a greater need for protamine and blood and had greater chest tube drainage, none of these changes were significantly different. Comparisons between activated clotting times (ACTs) and actual heparin levels revealed a good correlation (0.886). Good correlations were also noted when manual factor assays were compared with automated assays using an automated analyzer suggesting the potential use of automation and profiling for these patients. Possible reasons for some of the most commonly encountered postoperative bleeding problems are discussed.

Adult↗