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Biomedical subjects

L Ballowitz

Publications and source records attributed to L Ballowitz.

At least 37 records · Page 2Linked to original sources
PubMed1978

Sephadex-gel filtration (SGF) in infant and adult Gunn rats.

SGF was compared in infant and adult homozygous Gunn rats. Without any drug application, the test was negative in the adult animals, whereas a remarkable percentage of positive SGF was obtained in 5-7-day-old rats, especially in those undernourished and/or intensely icteric. Unexpectedly, in infant rats the rate of positive SGF after sulfadimethoxine injection was lower than in the untreated control group. Moreover, in 9-10-day-old animals who had positive SGF before the injection, the test became negative 15-20 min after sulfadimethoxine application in vivo. No convincing explanation could be given, but drug interference with the binding capacities of the Sephadex column could be excluded by appropriate in vitro tests.

Age Factors↗
PubMed1977

Phototherapy in Gunn rats. A study to assess the photobiologically most effective radiant energy and dose/response relationships.

In order to get a more realistic spectral efficiency curve and to evaluate dose/response relationships in phototherapy, homozygous weanling Gunn rats -- nondepilated, with fur -- were illuminated under standardized conditions with 8 different fluorescent tubes. Some of the tubes were operated with different electric power. Clear spectal differences in the extent and the rapidity of the bilirubin decay could be ascertained. Furthermore, the sharpness of the bilirubin decrease depended on the baseline concentration. For the calculations the animals were therefore divided into 3 groups with starting levels of larger than or equal to 8 mg%, 6.5--7.9 mg% and less than 6.5 mg%. Correlating the spectral power distribution of the lamps with the bilirubin decomposition found in the experiment, the spectral response function s(lambda)bili, rel was calculated by an integral method. A comparison of our results with data from the literature shows that so far near UV radiation was evaluated too high. A new radiometer for digital measuring the effective irradiance Ebili was developed. On a logarithmic scale a comparatively sharp dose/response relationship could be demonstrated in dependence on the measured effective radiant exposure. Serum bilirubin decrease is directly proportional to log Ebili. A dose of about 2.5 mW - h/cm2 is necessary to achieve a constant serum bilirubin decrease at all. Good results were obtained at doses of about 35 mW - h/cm2 with the most efficient being at 160 mW - h/cm2. Highly effective doses can be applied with different types of lamps. However, there are great differences in the time of illumination required. 24 h are necessary with daylight tubes (Osram L 20 W/19) to apply 20 mW - h/cm2, whereas the same dose is already attained after 4 h with BAM blue tubes (Philips). The accuracy of the radiometer was finally controlled by screening Westinghouse special blue and Osram standard blue tubes with black tapes, so that the effective irradiance (Ebili) corresponded to that of Osram daylight tubes. The bilirubin decrease observed after this manipulation was nearly identical (not exceeding 1 SD of the daylight values). Since bilirubin decrease was sharper in the first few hours of illumination, continuous phototherapy was compared in some tests with 3 intermittent schedules: (a) 4 h light, 4 h dark, 4 h light; (b) 5 h light, 2 h dark, 5 h light, (c) alternately 2 h light and 2 h dark. There was no indication that more bilirubin could be removed per hour with intermittent phototherapy than with continuous illumination.

Animals↗
PubMed1976

The influence of various aminoglycoside preparations on bilirubin/albumin binding.

The effect of antibiotics of aminoglycoside structure on the albumin binding of bilirubin has been tested in homozygous (jaundiced) Gunn rats aged 3-5 days. The following drugs were investigated: different preparations of gentamycin, kanamycin, tobramycin and sisomicin. The animals received 50-75% of the LD50 of heterozygous (non-jaundiced) Gunn rats. Mortality, weight gain and changes in the plasma bilirubin concentration were recorded. It was found that the displacement of bilirubin from albumin is caused by the different stabilizers used and not by the antibiotic itself. With the exception of lyophilized preparations of gentamycin for intrathecal application all vials contain different amounts of these preservatives. Special preparations used during the newborn period contain relatively more of these stabilizers. The toxicity of the additives has already a negative influence on the LD50 for heterozygous Gunn rats when the low dosed Refobacin and Sulmicin vials are given. For Refobacin (production 1973/74) the tolerance is reduced by nearly 50%. The toxicity caused by the stabilizer alone is even more marked when given to homozygous (jaundiced) Gunn rats. It becomes evident that benzylalcohol is the substance responsible for the displacement of bilirubin from albumin. The serum concentration of bilirubin decreases for 3-24 hrs depending on the doses given to the animal. This offers the opportunity to measure the competitive displacement of bilirubin easily and exactly. The free unbound, unconjugated bilirubin tends to diffuse into the lipid of the brain with resultant kernicterus. This was shown in histochemical preparations of the cerebellum of young homozygous Gunn rats. Using enzyme reactions for lactic acid dehydrogenase and NADH2-tetrazolium reductase the cytotoxic effect of bilirubin on PURKINJE cells could be demonstrated. The effect of the stabilizers used in the other antibiotic drugs tested can be neglected under clinical conditions. Finally the steepness and duration of the decrease of plasma bilirubin after injection of the dangerous stabilizers was studied in animals of different age (3-5 days; 3-4 weeks). Different results observed can be explained by the more rapid metabolism of benzoates in older animals. However, it remains an open question at what age Gunn rats reflect most precisely the human situation in premature and newborn babies.

Aminoglycosides↗
PubMed1975

Anoxic encephalopathy with predominant involvement of basal ganglia, brain stem and spinal cord in the perinatal period. Report on seven newborns.

This study reports subcortical lesions in 7 newborn babies after transient circulatory arrest and/or asphyxia. Basal ganglia, diencephalon, tegmentum of the brain stem and spinal grey matter exhibited extensive necroses in a columnar pattern. The lesions of the telencephalic and cerebellar cortex are less prominent. The spinal cord, available in 3 children, revealed subtotal neuronal loss in all segments. The lesions represent the extreme anoxic damage of the CNS in the perinatal period, comparable with brain death in the adulthood. Moreover, the pattern with predominating subcortical lesions indicates that anoxia affects the grey matter in all levels of the CNS.

Asphyxia Neonatorum↗
PubMed1975

Growth hormone and cortisol in neonates during phototherapy.

In 22 neonates plasma growth hormone (GH) and cortisol concentrations were measured during phototherapy which was administered because of hyperbilrubinemia. These values were compared to the hormone levels before and after therapy and to control values taken from healthy nursery infants. Phototherapy significantly increased GH concentrations to 195% plus or minus 108 (SD)(healthy control group = 100%). Cortisol was not found to be augmented. There was no correlation between GH and cortisol, nor between bilirubin and GH or cortisol. The mechanisms by which phototherapy induces GH increase are not evident. However, this may be due to constant covering of the eyes, deprivation of the day-night rhythm, or other environmental alterations that are brought about by incubator care.

Bilirubin↗