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Biomedical subjects

L Kramer

Publications and source records attributed to L Kramer.

At least 181 records · Page 10Linked to original sources
PubMed1979

Metabolic balances of cadmium, copper, manganese, and zinc in man.

Balance studies of cadmium, copper, manganese, and zine were carried out under constant dietary conditions in eight adult males during two calcium intake levels of 200 and 800 mg/day and in an additional single case during a calcium intake of 1500 mg/day. The dietary content and the excretions of these elements in urine and stool were determined. The mean dietary content of cadmium was 32.9 micrograms/day, of copper 1020 micrograms/day, of manganese 2130 micrograms/day, and of zinc 12.4 mg/day. The ratio of the fecal/urinary cadmium excretion was approximately 1.5 and the main pathway of excretion of the other three elements was via the intestine, while the urinary excretions were very low. The different trace element balances were either slightly negative or in equilibrium, except that the zinc balances was positive in 50% of the cases. All balances should be considered maximal values, as the losses in sweat were not determined. The calcium intake level had little effect on the excretion and retention of these trace elements.

Adult↗
PubMed1978

Effect of a high protein (meat) intake on calcium metabolism in man.

The effect of a high protein (meat) intake of 2 g/kg on the calcium excretions and retention and on the intestinal calcium absorption was studied in man. In the control study the protein intake averaged 1 g/kg. The studies were carried out during a low calcium intake of 200 mg/day and a normal calcium intake of 800 mg/day. Two additional studies were carried out during a calcium intake of 1100 mg/day and one during a 2000 mg calcium intake. During the high protein-low calcium intake and during the 800 mg calcium intake the urinary calcium did not significantly increase. It increased moderately in two studies during the higher calcium intakes, however, these excretions decreased with time to control levels. The lack of a significant increase of the urinary calcium in the majority of the studies is probably due to the higher phosphorus content of the high protein intake. The calcium absorption, determined with 47Ca, the fecal calcium and calcium balances did not differ significantly during the high protein intake. In studies carried out during a low protein (meat) intake of 0.5 g/kg the urinary calcium changed little and the fecal calcium, the 47Ca absorption, and the calcium balance remained unchanged.

Adult↗
PubMed1978

Magnesium-fluoride interrelationships in man II. Effect of magnesium on fluoride metabolism.

The effect of magnesium on the fluoride balance was investigated in man by determining metabolic balances of fluoride and magnesium in control studies and during magnesium supplementation. The magnesium intake averaged 264 mg/day in the control studies and 825 in the experimental studies. The studies were carried out during four calcium intakes that ranged from 200 to 2,200 mg/day and during phosphorus intakes ranging from 800 to 2,000 mg/day. The studies were carried out during a fluoride intake of about 4 mg/day that was due to the dietary fluoride content and the intake of water and during a high fluoride intake of 25 mg/day that was due to the addition of sodium fluoride. During the high magnesium intake, both the urinary and fecal magnesium excretions increased and the magnesium balances became more positive. These changes were not associated with any significant changes of either the urinary or fecal fluoride excretions or of the fluoride balances during the different intakes of calcium phosphorus, or fluoride.

Adult↗
PubMed1977

Hematologic effects of xylazine when used for restraint of Bactrian camels.

Xylazine was found to be a safe and reliable drug for chemical restraint of Bactrian camels (Camelus bactrianus). Dosages of 0.27 to 0.51 mg/kg of body weight provided adequate sedation for the performance of various procedures (e.g., tuberculin testing, lymph node biopsy, and electroejaculation). Hematologic and serum biochemical values for camels restrained manually were compared with those for camels restrained with xylazine. Xylazine-treated camels had significantly lower values for RBC, hemoglobin, and packed cell volume, and significantly higher blood glucose concentrations. Venous blood gas analyses did not reveal any major acid-base disturbances resulting from the use of xylazine. Rapid arousal from the sedative effects of xylazine occurred after the intravenous administration of doxapram hydrochloride in dosages of 0.05 to 0.13 mg/kg of body weight.

Animals↗
PubMed1977

Magnesium-fluoride interrelationships in man. I. Effect of fluoride on magnesium metabolism.

Metabolic balances of fluoride and magnesium were determined in man in control studies and during fluoride supplementation. The studies were carried out during three intake levels of calcium (200, 1,400, and 2,200 mg/day) and during two intake levels of phosphorus (800 mg and 1,400 mg/day). The intake of about 10 mg fluoride per day, given as NaF, resulted in a two- to threefold increase of the urinary and fecal fluoride excretion. However, during the high fluoride intake, the urinary magnesium remained about the same, the fecal magnesium increased slightly, and the magnesium balances did not differ significantly. This was the case whether fluoride was given during a low or high calcium intake in the absence or presence of added phosphorus. Similar results were obtained with large doses of fluoride (40-45 mg/day) given to patients with osteoporosis. The studies have shown that supplemental fluoride ranging from 10 to 45 mg/day did not affect the magnesium balance during calcium intakes that ranged from 200 to 2,200 mg/day and during phosphorus intakes that ranged from 800 to 1,400 mg/day.

Calcium, Dietary↗
PubMed1976

The problem of nonstationary ion fluxes in excitable membranes.

Time-dependent electrodiffusion through a membrane is analysed within a simple model treating the boundary-layers in a consistent manner. It is shown that time-independent reversal potentials for the ion fluxes exist only under steady-state conditions. We argue that this result holds very generally. Therefore nonstationary effect like ion storage and depletion inside the membrane should not contribute to the phenomena of excitability.

Biological Transport↗
PubMed1976

Pressure monitoring devices. Overlooked source of nosocomial infection.

Contaminated pressure monitoring devices recently have been implicated as a source of epidemic organisms in three outbreaks of nosocomial bacteremia, one outbreak of candidemia, and one outbreak of hepatitis. Measures necessary to prevent monitoring-related infections have not always been appreciated or taken. As a minimum, pressure monitoring devices should be sterilized between use with different patients; strict aseptic technique should be employed when setting up and using monitoring systems; and each patient's monitoring tubing, fluid, and monitoring devices should be changed at regular intervals.

Blood Pressure Determination↗
PubMed1976

Effect of conventional and newer forms of treatment on calcium absorption in osteoporosis.

Studies carried out in this Research Unit and by others have shown that patients with osteoporosis absorb less calcium from a high calcium intake than do patients without osteoporosis. To determine whether various treatment modalities would increase the intestinal absorption of calcium, the effects of conventional and new methods were investigated. Tracer doses of 47Ca were given orally to determine the absorption of calcium. Calcium balances were also determined. Estrogen decreased urinary calcium and testosterone increased the nitrogen balance. Vitamin D and strontium increased the urinary calcium but did not increase calcium absorption. Of the newer compounds, fluoride did not affect calcium absorption but decreased urinary calcium. Phosphate had a similar effect. Infusions containing up to 15 mg calcium/kg, given for 6 or 10 days, increased the retention of calcium but did not increase its absorption.

Adult↗
PubMed1975

Interpretation of invertebrate photoreceptor potentials in terms of a quantitative model.

It is known from voltage-clamp experiments on visual cells of Limulus and Balanus that the total membrane current can be separated approximately into a dark current JD and a light-induced current JL such that each part has a time-and intensity-independent reversal potential. In addition JL can be represented approximately as a product of a nonlinear, time independent current-voltage characteristics J0L (v) and an "activation factor" xa which depends on light intensity and time. J0L(V) can be described by a simple electro-diffusion membrane model (for JD we use the same model). A set of kinetic equations including amplification, latency and light adaptation leads to a determination of xa for photoisomerization of single rhodospin molecules and for arbitrary light signals. The receptor potentials calculated show many features of the experiments on Limulus, Balanus and Astacus.

Adaptation, Physiological↗
PubMed1975

Effect of calcium and phosphorus on fluoride metabolism in man.

The effect of orally administered calcium and phosphorus on the fluoride balance was studied in man during a low fluoride intake of about 4 mg/day and a high fluoride intake of 14 mg/day. Three calcium intake levels averaging 223, 1,481, and 2,312 mg and two phosphorus intakes averaging 915 and 1,430 mg/day were used. Calcium or phosphorus used singly or combined did not affect the urinary fluoride. Increasing the calcium intake from an average of 223 to 1,481 and to 2,312 mg/day during the low fluoride intake increased the fecal fluoride only slightly, from 0.13 to 0.17 and 0.20 mg/day, respectively, and during high fluoride intake from 0.31 to 0.58 and 0.56 mg/day, respectively. The addition of phosphorus to the low calcium intake did not change the fecal fluoride excretion during either low or high fluoride intake, but the fecal fluoride increased during the two higher calcium intakes by a factor of 1.5. As the fecal fluoride was very low in the control study and was still relatively low in the experimental studies, the increase in fecal fluoride did not change the fluoride balances. The studies have shown that the increased levels of calcium and phosphorus used had little effect on fluoride metabloism in man.

Adult↗
PubMed1975

Excretion of retained fluoride in man.

In fluoride studies performed in man the excess fluoride excretions in urine and stool over and above the base-line excretions were determined following the discontinuation of fluoride supplements. The fluoride supplements contained either 9.1 mg fluoride as sodium fluoride, given daily for 32 days, or 7.6 mg fluoride as fish protein concentrate (FPC), given daily for 26 days. Following discontinuation of these fluoride supplements the excess fluoride excretions were low and of short duration, in most cases for 6-12 days. Since the fluoride supplements were given for a known period of time, the fluoride retention could be calculated from the fluoride balances, and the excess fluoride excretion corresponded to 9.1% of the retained fluoride given as NaF and to 14.1% of the retained fluoride given as FPC. The excess fluoride was predominantly excreted via the kidney, i.e., 87% of the total excess fluoride excretion was passed in urine and only 13% in stool.

Adult↗