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Biomedical subjects

L Kramer

Publications and source records attributed to L Kramer.

At least 163 records · Page 9Linked to original sources
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↗
PubMed1975

Dietary fluoride intake of infants.

The fluoride content of various commercially available food items used in the preparation of the infant diet for the age groups from birth to 6 months has been analyzed and the total daily fluoride intake has been calculated on the basis of these data. The dietary fluoride intake totaled 0.32 mg/day for infants in the age group 1 to 4 weeks, increased in the subsequent months due to increasing food intake, and totaled 1.23 mg for infants 4 to 6 months of age. These fluoride intakes expressed per kilogram of body weight ranged from 0.07 mg/kg in the newborn to 0.16 mg/kg in the 6-month-old infant.

Animals↗