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Biomedical subjects

C Brown

Publications and source records attributed to C Brown.

At least 469 records · Page 26Linked to original sources
PubMed1983

Compressive, invasive referred pain to the shoulder.

The painful shoulder can be the presenting complaint of a wide variety of local, as well as systemic, problems. Compression of the brachial plexus or occlusion of the subclavian vessels caused by narrowing of the thoracic outlet is best diagnosed by a thorough history and physical examination, and by performing the appropriate test maneuvers. Patients who do not respond to an exercise program to strengthen the shoulder girdle may require surgical excision of the first rib to enlarge the thoracic outlet. Referred pain in the shoulder originating from the cervical spine or peripheral nerves can be determined by cervical spine roentgenograms and nerve conduction tests. Neoplasms and parenchymal disease of the lung, and infections of the pleural and subdiaphragmatic areas can refer pain to the shoulder through the phrenic nerve. For those patients with persistent shoulder pain and no discernible musculoskeletal abnormalities who do not respond to standard therapeutic measures, another source of the shoulder pain should be sought.

Diagnosis, Differential↗
PubMed1983

Pyrazole effects on mutagenicity and toxicity of dimethylnitrosamine in Wistar rats.

The correlation between the in vivo toxicity and in vitro mutagenicity of dimethylnitrosamine and the activity of dimethylnitrosamine demethylase I (DMND I) after pyrazole treatment of rats was studied. The biological effects of pyrazole were measured either as toxicity to the rats or as mutations to Salmonella TA 92. A dose-response relationship was observed between DMND I activity and the administered dose of pyrazole. Pyrazole administration increased the toxicity of dimethylnitrosamine when measured as a 50% lethal dose or as a histopathological effect on the liver. Phenobarbital and methylcholanthrene administration did not have any effect on the activity of DMND I or on the number of histidine-revertant colonies when tested using the liquid suspension method in the presence of dimethylnitrosamine and the reduced nicotinamide adenine denucleotide phosphate-generating system. When microsomes from the pyrazole-treated animals were used in the mutagenesis assay, there was a linear correlation between DMND I activity and the number of histidine-revertant colonies. It is concluded that pyrazole treatment of animals increases the activity of liver DMND I, the toxicity of dimethylnitrosamine, and the number of mutations.

Animals↗
PubMed1982

Complete reversal of chronic ethanol polydipsia by schedule withdrawal.

Rats exposed to daily 3-hr intermittent food delivery sessions (binging) chronically ingested excessive amounts of either H2O or 5% EtOH (mean 7.1 g/kg/3-hr). Withdrawing the intermittency of the feeding schedule once every 10 days (single-ration probe session) resulted in reduction of fluid intakes (both H2O and EtOH) to the level of animals always given daily single-ration sessions. This complete dependence of elevated fluid intake levels on the intermittent feeding schedule was unaffected by either the number of probes previously administered (0 to 11) or the duration the feeding schedule was maintained before introduction of the first probe session (29 or 109 days). The results of the probe sessions demonstrated that a history of ethanol overindulgence was not a sufficient condition for the maintenance of overdrinking. Continued overindulgence required the continued presence of the original inducing conditions. Ethanol-polydipsic animals exposed to periodic probe sessions also developed a slow rise in binge session intake. No such increase was observed in the water-polydipsic animals.

Animals↗
PubMed1982

Mevalonic acid in human plasma: relationship of concentration and circadian rhythm to cholesterol synthesis rates in man.

We tested the hypothesis that the rate of cholesterol synthesis in tissues determines the concentrations of mevalonic acid (MVA) in plasma. We found that plasma MVA concentrations were correlated (i) with increased rates of whole-body cholesterol synthesis (measured by sterol-balance methods) in patients treated with cholestryamine resin (ii) with decreased rates of whole-body sterol synthesis (indicated by conversion of labeled acetate to sterol in freshly isolated mononuclear leukocytes) in out-patients after 4 weeks on a cholesterol-rich diet. In addition, a diurnal rhythm of plasma MVA concentrations was observed in patients whose activities were strictly controlled on a metabolic ward. At the peak of the rhythm (between midnight and 3 a.m.) MVA concentrations were 3-5 times greater than at the nadir (between 9 a.m. and noon). Furthermore, a relationship between the diurnal rhythm of plasma MVA and endogenous cholesterol synthesis is suggested by our finding that the plasma MVA rhythm was suppressed by cholesterol feeding (1,200 mg/day) and abolished by a 12-day fast. The presence in human plasma of MVA, an obligate precursor of cholesterol, in amounts apparent related to the rate of cholesterol synthesis offers a noninvasive, nonisotopic method for studying cholesterol synthesis in man.

Cholesterol↗
PubMed1982

Evidence for stereospecificity of the P1-purinoceptor.

1 The effects of adenosine, 5'-N-ethylcarboxamidoadenosine (NECA), 2-chloroadenosine, 2-azidoadenosine, and their L-enantiomers were examined on driven left atria, trachea and transmurally stimulated ileum of the guinea-pig. 2 In each tissue the order of potency of the D-enantiomers for producing inhibitory effects was NECA greater than 2-chloroadenosine greater than 2-azidoadenosine greater than adenosine. 3 The log concentration-response curve of each agonist was shifted to the right in the presence of the P1-purinoceptor antagonist, theophylline. 4 Dipyridamole, which blocks adenosine uptake, potentiated the effects of adenosine but not those of the D-enantiomers of adenosine analogues. 5 The greater potency of the adenosine analogues therefore, is at least partly due to their resistance to tissue uptake and subsequent enzymatic destruction. 6 The L-enantiomers of adenosine and its analogues did not produce inhibitory responses in the driven left atria or transmurally stimulated ileum. At high concentrations relaxations of the tracheal muscle were obtained, with the potency series L-NECA greater than 2-chloro-L-adenosine greater than 2-azido-L-adenosine greater than L-adenosine. 7 It is concluded that the postsynaptic P1-purinoceptors in the guinea-pig atria and trachea and the presynaptic P1-purinoceptors on cholinergic nerve terminals in guinea-pig ileum are stereospecific for the D-enantiomers of adenosine and its analogues.

2-Chloroadenosine↗
PubMed1982

Is the transit time of a meal through the small intestine related to the rate at which it leaves the stomach?

Using non-invasive techniques, we investigated how varying the size or composition of a meal altered the rate at which it passed through the stomach and small intestine in normal volunteers. Increasing the size of the meal by doubling the absorbable components delayed gastric emptying, did not significantly influence the time taken for the head of the meal to reach the caecum, but retarded the entry of the bulk of the meal residues into the caecum. Incorporating fat in the meal slowed gastric emptying, but did not significantly affect small bowel transit time. The addition of the unabsorbable disaccharide lactulose (in place of an equivalent amount of sucrose) accelerated small bowel transit time, but did not significantly influence gastric emptying. Thus, our results indicated that changes in small bowel transit time could occur independently of changes in gastric emptying in normal healthy subjects.

Adult↗
PubMed1982

Renal phosphate handling in nephrotic syndrome during water immersion.

In 11 patients suffering from nephrotic syndrome, renal phosphate handling was studied in water immersion up to the neck. There was a rapid onset of phosphate diuresis which continued to increase throughout water immersion; and an increase in fractional excretion of phosphate (FEPO4) continuing throughout immersion and decreasing in the hour after immersion. TmPO4/GFR did not change on immersion. TmPO4/Inulin clearance gave higher figures than TmPO4/creatinine clearance due to secretion of creatinine in 9 of 11 patients. There was a transitory increase in PTH during immersion, but mean immersion plasma levels of PTH did not change when compared to preimmersion control values. FEPO4 was more frequently significantly correlated with FECL than to FENa in nephrotics.

Chlorides↗
PubMed1982

Furazolidone in turkey tissues following a 14-day feeding trial.

Feed supplemented with furazolidone was fed to turkeys on a research farm near Modesto, CA. The birds fed furazolidone-medicated feed were housed in isolated pens in a manner to prevent any cross contamination from an adjoining treatment. Furazolidone-medicated feed was supplied to the ration for 14 days prior to withdrawal with two exceptions; the controls were not fed medicated feed, and a 400 g/ton treatment was fed for 24 hr prior to processing. Treatments, representing different withdrawal periods, ranged from 0 to 21 days. Two 400 g/ton treatments with 0-day withdrawal periods were included in the study. One of these treatments involved a 14-day medicated feeding period while the other was for 24 hr. All other treatments were fed medicated feed at the rate of 200 g/ton. Tissue samples from the processed birds included skin, fat, liver, kidney, as well as breast and thigh muscle. No detectable residues were found in any of the liver, kidney, fat, or muscle tissues at any of the withdrawal periods including the 0-day withdrawal groups. Skin tissues contained detectable furazolidone residues only in the 0-day withdrawal treatments, and even these levels were below the 2 ppb level.

Administration, Oral↗
PubMed1981

Freeze-fracture cytochemistry: replicas of critical point-dried cells and tissues after fracture-label.

Applications of the new fracture-labeling techniques for the observation of cytochemical labels on platinum-carbon replicas are described. Frozen cells, embedded in a cross-linked protein matrix, and frozen tissues are fractured with a scalpel under liquid nitrogen, thawed, labeled, dehydrated by the critical point drying method, and replicated. This method allows direct, high-resolution, two-dimensional chemical and immunological characterization of the cellular membranes in situ, as well as detection of sites within cross-fractured cytoplasm and extracellular matrix.

Animals↗
PubMed1981

Carcinoma of the hepatic duct junction.

A series of 54 patients with carcinoma of the hepatic duct junction is reveiwed. The condition is probably less rare than previous publications would suggest as the condition is frequently missed at operation. An account of the presentation, investigation and treatment of these patients is given, as well as the results obtained. In the discussion that follows, it is pointed out that if systematic investigation is carried out, with particular regard to adequate radiological investigations, both prior to and during surgery, the correct diagnosis can be made, although histological proof may be difficult to obtain. These tumours are seldom resectable, but good and worthwhile palliation may be obtained.

Adult↗
PubMed1981

Intracavitary bleomycin for the control of malignant effusions.

The results of treatment with intracavitary bleomycin are reported in twenty patients with a malignant pleural effusion and five patients with malignant ascites. The control rate was 17/20 (85%) patients with malignant pleural effusions and 3/5 (60%) patients with malignant ascites. Toxicities were minimal with fever being the most common side effect in four patients (16%. Bleomycin is an effective and nontoxic sclerosing agent.

Adult↗
PubMed1981

Renal salt and water handling in water immersion in the nephrotic syndrome.

1. Eleven nephrotic patients were immersed up to the neck in 1.3 m of water at 34 degrees C for 4 h. 2. A diuresis began, within the first hour of, and continued throughout, immersion. The urine osmolality fell significantly and decreased to hypotonic levels in the first hour of immersion and increased gradually during the remainder of immersion and postimmersion. 3. Throughout immersion there was a steady increase in urinary sodium and chloride excretion and a sharp fall in the postimmersion hour. 4. Overall fractional excretion of sodium and of chloride increased steadily throughout immersion and fell during the post-immersion hour. 5. There was an increase in urinary potassium excretion on immersion but no change in fractional excretion of potassium. There was an initial increase in distally reabsorbed sodium/chloride on immersion, as expressed by positive values of CH2O in the first hour of immersion. 6. Plasma aldosterone levels were initially elevated in only two out of nine patients. There was a significant fall in plasma aldosterone levels on immersion, but there was no correlation between sodium/chloride handling and aldosterone levels on immersion.

Adolescent↗