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Biomedical subjects

J Kleinschmidt

Publications and source records attributed to J Kleinschmidt.

At least 37 records · Page 2Linked to original sources
PubMed1985

Passive smoking under controlled conditions.

Ten healthy subjects were exposed to passive smoking at a high level corresponding to 25-30 ppm CO in the ambient air for 3 h. All subjects were exposed at the same time in a climatic chamber especially designed for exposure experiments. Despite an identical exposure rate considerable interindividual variability of subsequent nicotine and cotinine levels in saliva, plasma and 24-h urine were observed. This variability was more prominent in nicotine than in cotinine levels. The kinetic pattern as reflected by saliva levels for up to 24 h was consistent with previous data found in active smokers. Nicotine levels found in saliva were markedly influenced by repeated sampling. This was not the case for cotinine levels. With regard to laboratory techniques RIA seems to be more sensitive than gas chromatography (GC). The results of this study suggest that measuring cotinine levels in 24-h urine with RIA is presently the most sensitive and reliable criterion for estimating exposure to passive smoking and for validating questionnaires or interviews about short-term exposure to passive smoking.

Adolescent↗
PubMed1985

Chromosome replication in early Xenopus embryos.

Early embryos of X. laevis achieve exceptional rates of DNA replication and chromatin assembly. These processes have been studied by microinjecting DNA templates into eggs or by incubating DNA in egg extracts. The egg is able to regulate replication of injected DNA without requiring specialized DNA sequences. Assembly of DNA into the nucleosome subunits of chromatin involves interaction of DNA with complexes containing two classes of acidic protein, namely nucleoplasmin and N1/N2.

Animals↗
PubMed1985

The pharmacokinetics of the bronchosecretolytic ozothin after intravenous injection.

Blood concentrations of the terpenes myrtenal, myrtenol, pionocarveol, verbenon and terbinhydrate in ozothin were investigated as a function of time after intravenous injection of 10 ml ozothin in 36 subjects. On each occasion 10 ml of the terpene mixture was injected into the inside right elbow. During the first 60 minutes after injection several 7 ml samples of citrate blood were withdrawn from the inside left elbow, immediately spun down and analysed by gas chromatography. Elimination of the terpenes from the blood during the first 10 minutes after injection appeared to follow a half-life time of three to four minutes with a second half-life time of 60 to 65 minutes. The concentration of these terpenes in expired air was determined in 27 subjects. Approximately 7% of the substances were eliminated via the lungs during the first 60 minutes. In a further series of experiments the concentration in subcutaneous fat during the first 24 hours after injection was studied. The whole terpenes concentrations range from 2.4 ng terpenes/g fat tissue to 0.8 ng terpenes/g fat at 24 hours.

Adipose Tissue↗
PubMed1984

Uptake of 3H-glycine in the outer plexiform layer of the retina of the toad, Bufo marinus.

The uptake of 3H-glycine in the retina of the toad, Bufo marinus, was investigated by light and electron microscopical autoradiography. Uptake of 3H-glycine was very prominent in large cell bodies in the inner nuclear layer as well as in discrete clusters in both the outer plexiform layer (OPL) and the inner plexiform layer. This pattern in similar to that described for 3H-glycine-accumulating putative interplexiform cells in goldfish, frog, and Xenopus retinas. Electron microscopical autoradiography of the OPL revealed large, grain-containing varicosities which had electron-lucent cytoplasm and contained both small, agranular and large, dense-core vesicles. The varicosities made extensive en passant and spine synapses in the OPL. Definitive identification of their postsynaptic targets was not achieved. However, autoradiographic analysis with 3H-GABA uptake as well as electrophysiological evidence suggests that axons but not cell bodies or dendrites of 3H-GABA-accumulating horizontal cells (H1 cells) are postsynaptic targets of the varicosities. The presence of dense-core vesicles in the varicosities suggested co-occurrence of glycine and a biogenic amine or neuropeptide. The indirect immunofluorescence technique was used to determine whether any such substances were present in the OPL of the toad retina. However, no specific labeling was found in the OPL for any of 19 substances tested. The extensive synaptic output provided by glycine-accumulating varicosities in the toad OPL may indicate an important role of glycine in the synaptic function of the distal toad retina. We suggest that these varicosities derive from a presumably glycinergic interplexiform cell.

Animals↗
PubMed1983

Carrier-mediated release of GABA from retinal horizontal cells.

H1 horizontal cells in goldfish retina are probably GABAergic and receive excitatory synaptic input from red cones. This input should affect the synaptic release of GABA from H1 cells. We studied the uptake and release of [3H]GABA from the isolated goldfish retina by use of autoradiography. When retinas were incubated in the light for 15 min in 0.72 microM [3H]GABA, heavy label was found over the somata (HS) and axon terminals (HAT) of H1 horizontal cells, and over pyriform amacrine cell bodies and their processes in sublamina b of the IPL. Postincubation of retinas, preloaded with [3H]GABA, in 0.5-10 mM L-glutamate or 0.1-10 mM L-aspartate, resulted in a dose-dependent and selective loss of [3H]GABA from HS and very little loss from HAT. This loss was not due to an efflux of metabolites of [3H]GABA or to any calcium-dependent vesicular release of [3H]GABA from HS. The glutamate-evoked release of [3H]GABA by H1 cells was sodium dependent, sensitive to substitution of lithium for sodium, and inhibited by nipecotic acid. In addition, [3H]GABA was released from HS by 0.1 mM ouabain but not by 50 mM potassium chloride. Our results suggest that the chemically evoked release of [3H]GABA from HS is mediated by a sodium-dependent transport carrier which may be responsible for the high affinity uptake of [3H]GABA by H1 cells as well. Since synaptic vesicles are not found at presumed synaptic release sites in H1 cells, we suggest that the GABA which is released synaptically from H1 cells may derive from a cytoplasmic pool of GABA and is released by means of a transport carrier. This carrier appears to depend primarily on the sodium concentration gradient across the H1 cell membrane rather than on the membrane potential of the H1 cell for its action. The relevance of the carrier-mediated release of GABA from HS in regard to the synaptic function of H1 cells is discussed.

Animals↗
PubMed1983

Neurofilaments contain alpha-melanocyte-stimulating hormone (alpha-MSH)-like immunoreactivity.

An antiserum to alpha-melanocyte-stimulating hormone (alpha-MSH) was found to contain antibodies to at least two types of determinants on the alpha-MSH peptide: one is present only on the free peptide, the other is shared with neurofilaments. Immunoblots from mouse brain showed the neurofilament crossreactivity to be located on proteins in the Mr 140,000 range. The neurofilament-crossreactive portion of the antiserum could be selectively absorbed out with a cytoskeletal preparation, which abolished all affinity of the antiserum to the retina but did not affect the labeling pattern in the pituitary. Absorptions with desacetyl-alpha-MSH and corticotropin seemed to indicate that the determinant shared with neurofilaments is not located at either end of the alpha-MSH peptide, but somewhere in between. The immunohistochemical labeling of the retina with the alpha-MSH antiserum was compared to the labeling with monoclonal antibodies against Mr 200,000 neurofilaments. In the adult retina the alpha-MSH-like immunoreactivity was found to be slightly more widespread; most consistently it was detectable in cell bodies of large ganglion cells, whereas the heavy neurofilament subunit was absent from somata and proximal axons of these cells. In the developing mouse brain, expression of the heavy subunit was found to lag 2-3 wk behind expression of the Mr 140,000 proteins. This confirms previous reports of a more restricted distribution and late expression of high molecular weight neurofilaments as compared to the lower subunits.

Animals↗
PubMed1981

[Hydrotherapy in swellings with special reference to lymphedema].

Is is to be stated in summary that the majority of positive arguments in the literature publications so far for the application of hydrotherapy in swellings there are weighty counter-arguments especially in lymphatic edema in the narrow sense. The present study (which is only preliminary because of the small number of cases) appears to indicate that these arguments are evidently not so weighty as was assumed hitherto. Even though unfortunately few clinically relevant alterations occurred with hydrotherapy alone, on the other hand, study indicates that we would have to prohibit patients with lymphatic edema from taking cold immersion baths. Hydrotherapy tends to have if anything a favorable influence on the basic psychological condition and according to the data available can be recommended as an additional measure.

Adult↗
PubMed1980

The effects of intraocular injection of kainic acid on the synaptic organization of the goldfish retina.

Kainic acid (KA), an extended analog of L-glutamate, was injected into the eyes of living goldfish. After survival times ranging from 15 min to 6 days, retinae were inspected for KA-induced degeneration at both the LM and EM levels. KA had little effect on photoreceptors, mixed rod-cone bipolar cells, Müller cells, at least two types of amacrine cells and the optic nerve. Reversible edema was seen in both rod and cone horizontal cells. Pure cone bipolar cells and the majority of amacrine cells appeared to be destroyed by KA. The effect of KA is selective not only on the cell types involved, but also in the location of KA-induced edema on the affected cells, i.e., soma and proximal portions of dendrites of cone horizontal cells as opposed to the distal ends of dendrites of rod horizontal cells. Implications of these data are discussed in regard to the use of KA as a probe for glutamatergic pathways in the retina. One hypothesis suggested by our results is that rods use glutamate whereas cones use aspartate as their neurotransmitter.

Animals↗
PubMed1979

[Model for the study of influences on fracture healing. Animal experiments].

Primary and secondary bone healing were studied for 30 and 60 days, respectively, by means of X rays, scintigraphy, determination of callus thickness, scintillation counter, and determination of bone mineral content. Primary bone healing was terminated after 30 days, secondary healing after 60 days. Scintillation counting proved to be a quantitative method, the other methods serving as controls. The different influences on bone healing can be quantitatively studied by means of this model.

Animals↗
PubMed1977

[Quantitative serum immunoglobulin determination: differential diagnostic significance for liver disease (author's transl)s].

The serum immunoglobulin (Ig) G, A, and M levels were investigated with respect to their differential diagnostic significance, pathogenesis and estimation of prognosis of different forms of liver disease. The sera of 204 patients with acute hepatitis, fatty liver I and II, and cirrhosis, and of 110 healthy adutls were quantitatively determined for immunoglobulins. 1. IgG- and IgA-concentrations higher than 2000 mg% and 330 mg%, respectively, indicate chronic aggressive hepatitis or cirrhosis, and exclude all other groups. 2. A clear correlation between HBsAG (Australia Antigen) and immunoglobulin content could not be demonstrated in any group; 3. A significantly elevated level of IgA was observed in alcoholic cirrhosis when compared to non-alcoholic cirrhosis. No such differences were found inhe other groups. 4. Acute and chronic persistent hepatitis show a similar increase of immunoglobulins. Thus persistent high levels of Ig following acute hepatitis indicate the development into a chronic hepatitis. 5. A relative increase of IgA rather than IgG corresponds to the degree of inflammatory activity of a liver process.

Chronic Disease↗
PubMed1975

Intracellular recordings from gecko photoreceptors during light and dark adaptation.

Intracellular recordings were obtained from rods in the Gekko gekko retina and the adaptation characteristics of their responses studied during light and dark adaptation. Steady background illumination induced graded and sustained hyperpolarizing potentials and compressed the incremental voltage range of the receptor. Steady backgrounds also shifted the receptor's voltage-intensity curve along the intensity axis, and bright backgrounds lowered the saturation potential of the receptor. Increment thresholds of single receptors followed Weber's law over a range of about 3.5 log units and then saturated. Most of the receptor sensitivity change in light derived from the shift of the voltage-intensity curve, only little from the voltage compression. Treatment of the eyecup with sodium aspartate at concentrations sufficient to eliminate the beta-wave of the electroretinogram (ERG) abolished initial transients in the receptor response, possibly indicating the removal of horizontal cell feedback. Aspartate treatment, however, did not significantly alter the adaptation characteristics of receptor responses, indicating that they derive from processes intrinsic to the receptors. Dark adaptation after a strongly adapting stimulus was similarly associated with temporary elevation of membrane potential, initial lowering of the saturation potential, and shift of the voltage-intensity curve. Under all conditions of adaptation studied, small amplitude responses were linear with light intensity. Further, there was no unique relation between sensitivity and membrane potential suggesting that receptor sensitivity is controlled at least in part by a step of visual transduction preceding the generation of membrane voltage change.

Adaptation, Ocular↗
PubMedDate not supplied

Efficient recombinant adeno-associated virus production by a stable rep-cap HeLa cell line correlates with adenovirus-induced amplification of the integrated rep-cap genome.

BACKGROUND: A possible procedure for the production of clinical grade recombinant adeno-associated virus type 2 (rAAV) would include the use of packaging cell lines, harboring the rep-cap genes and the vector, combined with a replication defective adenoviral plasmid to provide the helper activities. Several studies have already shown that rAAV can be efficiently assembled by infecting the stable packaging cell line with adenovirus. However, the direct comparison with an adenoviral plasmid has never been reported. METHODS: To investigate this point, a clone of HeLa and 293 cells harboring one to two rep-cap copies per cell genome (HeRC32 and 293RC21, respectively) were generated. Recombinant AAV was produced by transiently transfecting the AAVCMVLacZ vector and supplying the adenoviral helper activities by either wild-type adenovirus or an adenoviral plasmid (pAdc). As a control, rAAV was similarly produced from naive Hela and 293 cells additionally transfected with a rep-cap plasmid. RESULTS: Despite satisfactory rAAV yields from Hela and 293 cells, we show that those from HeRC32 and 293RC21 cells dramatically decrease when adenovirus is replaced by the adenoviral plasmid (pAdc). The analysis performed to identify the factors hampering efficient rAAV assembly by HeRC32 cells in the presence of pAdc shows that: (1) while upon adenovirus infection the integrated rep-cap genome undergoes a dramatic amplification leading to a 100-fold increase in the rep-cap copy number, no amplification is detected upon transfection of pAdc; (2) in pAdc-transfected HeRC32 cells, the intracellular localization of the adenovirus E4orf6 and E1B-55kDa proteins is abnormal as compared to adenovirus-infected cells. CONCLUSIONS: This study documents that stable rep-cap cells lines are severely hampered for rAAV assembly when a replicative adenovirus is substituted with an adenoviral plasmid. Furthermore, our results also suggest that the lack of amplification of the rep-cap genes, eventually combined with the altered distribution of the adenoviral proteins, E4orf6 and E1B-55kDa, is related to the low rAAV yields observed under these conditions.

Adenovirus E1B Proteins↗