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Biomedical subjects

C F Ramberg

Publications and source records attributed to C F Ramberg.

At least 37 records · Page 2Linked to original sources
PubMed1979

Plasma retinol transport and clearance in hypervitaminosis A.

Effects of mild and severe hypervitaminosis A on retinol transport and clearance were studied in mature ewes. Excessive vitamin A intake was assoicated with high concentrations of vitamin A in plasma and liver, with elevated serum enzymes, with decreased feed consumption and packed cell volume, and with epithelial hyperplasia. Retinol transport in plasma increased 6- to 8-fold with excessive dietary vitamin A, was greater with mild hypervitaminosis A, and increased exponentially with vitamin A concentration in plasma. Clearance of retinol from plasma increased 2-fold with hypervitaminosis A, exhibited a greater response in the mild group, and increased linearly with vitamin A concentration in plasma. The relationship of clearance to vitamin A concentration in liver was described best by a power function. Retinol clearance represents a mechanism to maintain vitamin A concentration in plasma and may be most effective below vitamin A concentrations of 135 microgram/dl plasma. With severe hypervitaminosis A, massive vitamin A accumulates in liver leading to hepatic dysfunction and a resultant decrease in retinol clearance from plasma.

Alanine Transaminase↗
PubMed1977

Hematological and metabolic responses to training in racing sled dogs fed diets containing medium, low, or zero carbohydrate.

In a 28 week study, 18 racing sled dogs were trained to maximal fitness in 12 weeks, sustained through a racing season of 12 weeks, followed by gradual of training of 4 weeks. The dogs were fed a predominantly cereal diet prior to the study; experimental diets containing more chicken and meat by products were introduced from the 2nd to the 4th week of training. On an energy basis, the diets contained protein, fat, and carbohydrate in the proportions of 39:61:0 (diet A), 32:45:23 (diet B), and 28:34:38 (diet C). Blood samples were taken at rest just before the start of training, at 6, 12,24 and 28 weeks; 33 variables were measured on most samples. The results were subjected to analysis of variance. No adverse effects were observed in dogs fed the extreme diet A. Significant relationships to training were shown by serum glutamic oxaloacetic transaminase, creatinine, packed cell volume, calcium, hemoglobin, and globulin. Serum cholesterol concentration increased with the introduction of the higher protein-fat diets; the high concentrations attenuated with time but rose again when training was abated. Dogs on diet A maintained higher serum concentrations of albumin, calcium, magnesium, and free fatty acids during the racing season than did dogs fed diets B or C. They also exhibited the greatest increases in red cell count, hemoglobin concentration, and packed cell volume during training. High values of red cell indices were not sustained through the racing season in dogs fed diet C. In addition to attributes already widely appreciated, viz. a higher energy density an digestibility, the carbohydrate-free, high-fat diet A appeared to confer advantages for prolonged strenuous running in terms of certain metabolic responses to training.

Animals↗
PubMed1977

Plasma clearance of [51Cr] albumin into the intestinal tract of normal and chronically diarrheal horses.

Five clinically normal, mature horses and 11 with chronic diarrhea were given 51Cr-tagged Cohn fraction V equine albumin intravenously. All urine and feces were collected separately, and blood for plasma analysis was taken periodically for 5 to 8 days after injection of the isotope. Plasma clearance of albumin into the intestinal tract of normal horses was calculated as 0.67 +/- 0.23 (SD) ml/kg of body weight/day, with 1.33 +/- 0.69% of the 51Cr dose appearing in the feces in 5 days. Of the 11 diarrheal horses, 8 had a plasma clearance of 0.49 +/- 0.21 ml/kg/day with 1.12 +/- 0.68% of the dose of 51Cr in a 5-day fecal collection, suggesting that excessive losses of plasma protein into the bowel was not a component of their intestinal disease. The 3 other diarrheal horses had a marked protein-losing enteropathy; 1 of these horses had granulomatous enteritis due to Mycobacterium avium infection; another had severe intercellular edema of small and large intestinal mucosa, cause unknown; and intestinal biopsies were not obtained from the 3rd horse. The results suggest that: (1) as with other species that have been studied, daily loss of plasma protein into the bowel of horses is small; (2) most horses with chronic diarrhea do not have protein-losing enteropathy.

Albuminuria↗
PubMed1976

Dietary calcium, calcium kinetics and plasma parathyroid hormone concentration in cows.

Kinetic analysis of radiocalcium data was combined with radioimmunoassays of plasma parathyroid hormone in nonpregnant nonlactating cows 4.5 to 7.8 years of age whose calcium intake was varied from 0.05% to 1.4% of the diet. Calcium intake had no significant effect on plasma concentration of calcium or parathyroid hormone. It had a slight but significant effect on the plasma phosphorus concentration. As calcium intake increased, calcium absorption increased but calcium removal from bone decreased so that total calcium transport into the exchangeable pool remained fairly constant. A decline in calcium clearance with age was accompanied by a fall in plasma parathyroid hormone concentration, and a decrease in calcium transport into the pool. These observations are consistent with feedback controls between plasma calcium, parathyroid hormone and calcium transport operating to maintain plasma calcium homeostasis as calcium clearance declined with advancing age.

Age Factors↗
PubMed1976

Normal and abnormal xylose absorption in the horse.

The D-xylose absorption test was applied to clinically normal horses and to horses with signs of gastrointestinal disease. A dosage of 0.5 grams of xylose per kilogram of bodyweight was useful in detecting horses that absorbed the pentose abnormally. The clinical findings were correlated with gross and microscopic findings by biopsy and at necropsy. Gastrointestinal lesions associated with abnormal xylose absorption were classified as: 1) villous atrophy; 2) edema of the lamina propria or 3) necrosis of the lamina propria.

Animals↗