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Biomedical subjects

M Klein

Publications and source records attributed to M Klein.

At least 451 records · Page 25Linked to original sources
PubMed1991

The influence of birth setting on the father's behavior toward his partner and infant.

As part of a controlled, clinical trial conducted to compare medical and psychological outcomes of a birth room and a conventional hospital setting, we examined the behavior of fathers toward their partners and infants. One hundred fourteen couples were systematically assigned to either locale by strict alternation. They learned about this allocation on arrival at the hospital in labor. Observations of fathers' behavior were made at midlabor and during home visits at three months and one year. During labor, fathers assigned to the conventional setting were more involved in helping and encouraging their partners. Parenting behavior was not influenced by the birth setting. Unexpectedly, fathers were more involved with their infants when the mothers had expressed less satisfaction with childbirth. Compensation behavior may explain these results, which can be seen as appropriately adaptive in the face of perceived environmental deficiencies affecting the laboring woman and the infant.

Adult↗
PubMed1991

Mapping of B-cell epitopes on the outer membrane P2 porin protein of Haemophilus influenzae by using recombinant proteins and synthetic peptides.

The P2 protein of Haemophilus influenzae type b has a porin activity and is the most abundant protein in the outer membrane. We have employed fusion protein constructs and synthetic peptides along with monoclonal antibodies to map B-cell epitopes in this protein. A linear, surface-exposed epitope was identified between residues 158 and 174. A second surface-exposed epitope was identified near the carboxy-terminal end of the protein (residues 319 to 341). Two additional B-cell epitopes were identified. One was localized between residues 28 and 55, whereas the other was located between residues 148 and 174. These epitopes were not present on the surface of intact H. influenzae cells. Thus, four distinct immunogenic and antigenic regions on the P2 protein have been identified.

Amino Acid Sequence↗
PubMed1991

Hydration in severe acute asthma.

Twenty children were studied during severe attacks of acute asthma to find out how dehydrated they were on admission to hospital. Mean body weight on admission was 97.8% of their reference stable weight seven to 10 days after the attack and in only three children was it less than 95% of the stable weight. Bedside assessment of dehydration was unreliable. The mean packed cell volume was significantly higher on admission than 7-10 days later (0.44 compared with 0.42, difference 0.02 SE 0.01). Serum sodium and potassium concentrations and osmolality on admission were within normal ranges. The degree of dehydration correlated best with a fall in blood pH. There was no association between the degree of dehydration and the recovery of the peak expiratory flow rate during the first 24 hours or thereafter. We conclude that mild dehydration is common in severe acute childhood asthma. Fluid given at a rate of 50 ml/kg/24 hours was safe and appropriate for these children.

Asthma↗
PubMed1991

31P-NMR study of different hypothyroid states in rat leg muscle.

Using phosphorus nuclear magnetic resonance spectroscopy, this study was undertaken to determine the effects of experimental hypothyroidism on muscle bioenergetics. The peaks of phosphocreatine (PCr), Pi, phosphodiesters (PDE), sugar phosphomonoesters, and ATP were obtained at rest, during a 2-Hz hindleg muscle stimulation, and during a subsequent recovery period from four groups of anesthetized rats as follows: one control and three hypothyroid (HT) groups treated by propylthyouracil during 2, 4, and 6 wk, respectively. Resting spectra showed a significant rise in Pi by 30% and decreased intracellular pH and PCr/Pi in all three HT groups. PDE progressively increased to 200% of its initial value with hypothyroidism duration. Muscle stimulation did not lead to significant differences in PCr depletion. The percentage of PCr recovery is less in HT muscle than in control muscle. An abnormal H+ metabolism is obvious in all three HT groups. These results indicate abnormal bioenergetics in HT muscle and suggest an impairment of mitochondrial metabolism and of the H+ efflux. They also evoke a high sensitivity of cellular energetics to thyroid deficiency.

Animals↗
PubMed1991

Muscle bioenergetic impairment in hyperthyroid man: a study by 31P NMR spectroscopy.

Phosphorus nuclear magnetic resonance spectroscopy was used to investigate muscle bioenergetics in 9 hyperthyroid patients who were compared with 9 normal subjects. Using the thenar muscle group as reference, the inorganic phosphate, phosphocreatine and intracellular pH were calculated at rest, during aerobic exercise (0.13 w) and post-exercise recovery. No difference was found at rest. After 5 min of exercise, the hyperthyroid patients exhibited a more important phosphocreatine depletion (41.2 +/- 8.2 vs 31.1% +/- 6.5, p less than 0.02) and a larger pH fall (6.65 +/- 0.04 vs 7.01 +/- 0.10, p less than 0.001) than the control subjects. The phosphocreatine recovery rate was not significantly different in hyperthyroid patients and control subjects. These results suggest that exercise requires more ATP in hyperthyroid patients than in normal subjects and that there is excessive dependence on glycolytic metabolism for ATP synthesis in hyperthyroidism. Phosphocreatine resynthesis, reflecting the oxidative metabolism, is not increased. These metabolic disturbances could also supply a partial explanation to the frequent exercise intolerance in hyperthyroid patients.

Adenosine Triphosphate↗
PubMed1990

Structural characterization of the human DNA topoisomerase I gene promoter.

We have isolated a genomic DNA fragment from HeLa cells containing the promoter region and the first two exons of the human gene encoding DNA topoisomerase I (hTOP1). Transcription of hTOP1 mRNA initiates at multiple sites which are clustered 247 nucleotides and 210 nucleotides upstream of the translation-initiation site of the protein coding region. The nucleotide sequence of the region preceding the transcription-initiation sites is G/C rich and contains sequence motifs which are known binding sites of the transcription factors Oct1 (octameric transcription factor 1), Sp1 and AP2 (activator protein 2). Furthermore, one cAMP-responsive element is present 50 nucleotides upstream of the transcription-initiation site nearest the 5' end. Neither TATA nor CAAT boxes were found in the promoter region of the hTOP1 gene. A 918-bp fragment containing the sequence elements described above drives the transient expression of a chloramphenicol acetyl transferase (CAT) gene sequence in transfected HeLa and 293 cells. In addition we analyzed a 10-kb fragment containing the promoter and exons 1 and 2 for regions of DNase I hypersensitivity. We detected one prominent DNase-I-hypersensitive region in the promoter close to the putative transcription-factor-binding sites and several weaker regions in intron 2.

Autoradiography↗
PubMed1990

Contributions of two types of calcium channels to synaptic transmission and plasticity.

In Aplysia sensory and motor neurons in culture, the contributions of the major classes of calcium current can be selectively examined while transmitter release and its modulation are examined. A slowly inactivating, dihydropyridine-sensitive calcium current does not contribute either to normal synaptic transmission or to any of three different forms of plasticity: presynaptic inhibition, homosynaptic depression, and presynaptic facilitation. This current does contribute, however, to a fourth form of plasticity--modulation of transmitter release by tonic depolarization of the sensory neuron. By contrast, a second calcium current, which is rapidly inactivating and dihydropyridine-insensitive, contributes to release elicited by the transient depolarization of an action potential and to the other three forms of plasticity.

Action Potentials↗
PubMed1990

[Myasthenia gravis: results of thymectomy in 550 patients].

Report is giving on 550 myasthenic patients who underwent thymectomy during the last 18 years. Results of thymectomy are analysed in separate groups and according to different aspects, including thymic tumours (13.63%), operations in childhood (9.64%), and combined cases (11.1%). The results are evaluated according to Disability Status Scale based on a point-system. Successive improvement was observed in the three series concerning the results of operation. Childhood myasthenia gravis gave the best results but thymectomy was beneficial in the combined group, in long-lasting myasthenia and in tumourous cases, too. There are quite a few factors influencing the results, such as the interval between the disease onset and thymectomy, the patients' age, thymoma, crisis-danger and the activity of the thymus gland reflecting in the number of the germinative centres. The more active the thymus, the better the results.

Humans↗
PubMed1990

Isotype modulation of idiotypic expression in recombinant isotypic variants of MOPC 315.

The influence of the CH1 domains of various isotypes on the expression of four Id of the IgA 2 mouse myeloma protein MOPC 315 was assessed. To this end, mammalian expression vectors containing the rearranged MOPC 315 VH gene along with the H chain genes of various isotypes were constructed. These vectors were then transfected into the L chain-expressing MOPC 315.26 cell line to produce the rIg. The effect of polyvalency on the ability of Ig to bind anti-idiotypic antibodies was tested by comparing idiotypic expression in a competitive ELISA using reduced and nonreduced MOPC 315 IgA and IgM species. Reduction produced a two- to fivefold decrease in their ability to inhibit the binding of three anti-idiotypic antibodies, but not that of the functionally univalent antibody D10. In contrast, reduction of MOPC 315 IgG proteins did not affect the binding of the anti-Id mAb, indicating that reduction of the interchain disulfide bonds did not alter idiotypic expression. The expression of idiotopes on reduced mouse rIgA, IgM and IgG and human IgG MOPC 315 molecules was then compared. The results showed that both human and mouse IgG recombinant antibodies exhibited an enhanced expression of the idiotopes recognized by antibodies D10 and F1, as compared to MOPC 315 IgA and IgM molecules. In contrast, the expression of idiotopes recognized by A2 and G3 mAb was not influenced by the H chain isotype. These data support the hypothesis that the conformation of certain idiotopes is modulated by the isotype of the CH1 domain.

Alkylation↗
PubMed1990

[Criteria and diagnosis of brain death].

"Brain death" ist the irreversible loss of function of the whole brain. The syndrome is identical with individual death. The correct determination of brain death is important as further treatment makes no sense and as tissue donation now can be taken into account. The recommendations of the scientific advisory board of the German General Medical Council for determination of brain death from 1986 as well as the own experiences with the "brain death syndrome" and the preparations for tissue donation are discussed.

Brain Death↗
PubMed1990

Simultaneous determination of Bordetella pertussis toxin and filamentous haemagglutinin concentrations by hydroxyapatite high-performance liquid chromatography.

A simple and rapid method for the simultaneous determination of Bordetella pertussis toxin (PT) and filamentous haemagglutinin (FHA) concentrations in fermentation broths has been developed. The rapid single-step analysis performed by hydroxyapatite high-performance liquid chromatography using a salt gradient with UV detection allows both the separation of PT from FHA and the measurement of their respective concentrations. The assay is highly reproducible. Over 35 lots of acellular B. pertussis vaccine production lots were examined and PT concentrations measured by high-performance liquid chromatography were found to be in good agreement with the values obtained by sodium dodecyl sulphate-polyacrylamide gel electrophoresis densitometry. The chromatographic conditions have been optimized to separate the intact holotoxin from its B-oligomer subunits.

Amino Acids↗
PubMed1990

A randomized, controlled trial of vitamin A in children with severe measles.

BACKGROUND: Measles kills about 2 million children annually, and there is no specific therapy for the disease. It has been suggested that vitamin A may be of benefit in the treatment of measles. METHODS: We conducted a randomized, double-blind trial involving 189 children who were hospitalized at a regional center in South Africa because of measles complicated by pneumonia, diarrhea, or croup. The children (median age, 10 months) were assigned to receive either vitamin A (total dose, 400,000 IU of retinyl palmitate, given orally; n = 92) or placebo (n = 97), beginning within five days of the onset of the rash. At base line, the characteristics of the two groups were similar. RESULTS: Although clinically apparent vitamin A deficiency is rare in this population, the children's serum retinol levels were markedly depressed (mean [+/- SEM], 0.405 +/- 0.021 mumols per liter [11.6 +/- 0.6 micrograms per deciliter]), and 92 percent of them had hyporetinemia (serum retinol level less than 0.7 mumols per liter [20 micrograms per deciliter]). Serum concentrations of retinol-binding protein (mean, 30.1 +/- 2.0 mg per liter) and albumin (mean, 33.4 +/- 0.5 g per liter) were also low. As compared with the placebo group, the children who received vitamin A recovered more rapidly from pneumonia (mean, 6.3 vs. 12.4 days, respectively; P less than 0.001) and diarrhea (mean, 5.6 vs. 8.5 days; P less than 0.001), had less croup (13 vs. 27 cases; P = 0.03), and spent fewer days in the hospital (mean, 10.6 vs. 14.8 days; P = 0.01). Of the 12 children who died, 10 were among those given placebo (P = 0.05). For the group treated with vitamin A, the risk of death or a major complication during the hospital stay was half that of the control group (relative risk, 0.51; 95 percent confidence interval, 0.35 to 0.74). CONCLUSIONS: Treatment with vitamin A reduces morbidity and mortality in measles, and all children with severe measles should be given vitamin A supplements, whether or not they are thought to have a nutritional deficiency.

Administration, Oral↗