Search PubMed⌕ Search

Biomedical subjects

H Alexander

Publications and source records attributed to H Alexander.

At least 199 records · Page 11Linked to original sources
PubMed1978

Investigations of hormones during early abortion induced by prostaglandin F2alpha and 15(S)-methyl-PGF2alpha.

In early pregnancy up the 7th week of pregnancy PGF2alpha was infused and 15(S)-methyl-PGF2alpha was applied i. m. to induce menstruation in 20 or 19 cases, respectively. In the tested form of application 15(S)-methyl-PGF2alpha is effective in 89 per cent of the cases and in 74 per cent complete abortion was achieved. PGF2alpha produced bleeding in 80 per cent only and complete abortion in 55 per cent. The differences in these two groups were not statistically significant. The steroid hormones estradiol and progesterone decrease in a successful application of PGs for induction of abortion and reach a value of 75 per cent at the onset of bleeding. The LH concentration in plasma becomes smaller too. In some cases there is a temporary increase in hormones shortly after starting treatment. The results could indicate that the considerable decrease in hormones before the onset of bleeding might be caused by an alteration of the corpus luteum, which is effective during early pregnancy.

Abortion, Induced↗
PubMed1977

[Advances in sphygmomanometry (author's transl)].

Problems of the accuracy and reliability of Riva-Rocci's non-invasive method of measuring blood pressure always arise when the cuff does not fit well, i.e. with a very conical upper limb, adiposity or in neonates or patients in shock. From thorough clinical investigations it appeared that the cuff used for blood pressure measurements in adults and the few models for neonates and children are too inaccurate. The cuff must enclose the limb completely and have a minimum ratio of breadth to length of 1 : 3. An integral inflatable cuff unit has been developed and clinically tested in our laboratory during the last two years. It consists of a heat-sealed polyolefine film.

Adult↗
PubMed1977

[Genetic activity of mouse oocytes during in vitro "spontaneous" maturation].

Mouse oocytes, liberated from ovarian follicles, resume meiosis in the obligatory presence of Ca++. PHMPS exerts a toxic effect on this mechanism. m-RNA synthesis, in contrast to that of r-RNA. seems to be required during the first hours of maturation in order to ensure realization of the following steps: in addition the 2nd maturation period, corresponding to the first polar body extrusion, depends on the presence of proteins synthesized during the chromatin condensation process and germinal vesicle breakdown. We suggest that it might be a factor responsible for microtubule formation in metaphase I.

Animals↗
PubMed1977

Accounting for natural tension in the mechanical testing of human skin.

A low-pressure suction device has previously been used to obtain quantitative information on the mechanical properties of human skin. Reducing the raw data from this technique was complicated by the fact that the skin is already biaxially loaded in the natural state and a rational basis on which to compare results obtained from different subjects was not available. Using a strain gauged pretension device, a procedure for determining the natural state tension and extension fields in the skin has been developed. The natural tension was then relaxed in the direction of testing and the suction device used to determine the two-dimensional skin tension-extension ratio response of the skin at a constant testing rate. The data from a number of subjects have been used to develop a new multidimensional stress-strain theory in terms of two material constants that are related to basic material characteristics of the dermis and are uniquely determinable regardless of the natural state stress field. Tests performed on the upper backs of 23 healthy adult males were used to investigate the variations in the material constants with age and sun-exposure habits. Age variations were found to corroborate earlier studies, and variations with sun exposure habits were related to known dermal collagen and elastin changes due to ultraviolet radiation. The apparent sensitivity of the testing procedure to physiologic state variables holds out the hope that mechanical properties characterization will be a useful tool in the evaluation of the severity of certain pathologic states and the effect of therapy.

Adult↗
PubMedDate not supplied

Morphological characteristics of tendon cells cultured on synthetic fibers.

Filamentous carbon is currently being used as an implant material for tendon and ligament repair in humans. This material acts as a scaffold for the organization of new fibrous tissue growth. Primary cultures of rat tendon fibroblast cells (1 degrees RTF cells) were grown on carbon, Dacron, polyethylene and Nylon fibers in vitro. The morphological characteristics of these cells were examined. The process of cell migration from tendon explant to fiber substrate was similar for all four materials. Three morphological categories of cells were observed on these materials. (1) spherical dividing cells, (2) spindle-shaped migrating cells, (3) sheath-like migrating or stationary cells. The morphological characteristics and orientational behavior of cultured fibroblasts on these fiber materials were strongly influenced by the diameters of the fibers and by fiber surface characteristics such as longitudinal striations. The possible mechanisms of cell response to substrate geometric configuration are discussed along with the clinical significance of these experiments.

Animals↗
PubMedDate not supplied

Mimicking the alloantigenicity of proteins with chemically synthesized peptides differing in single amino acids.

Recent studies have shown that short chemically synthesized peptides very often induce antibodies which react with the cognate sequence in the intact folded protein. Since such antibodies react with known regions of proteins, they are of predetermined specificity and offer a precision not previously possible with immunological probes. A basic concept emerging from the use of such antibodies in viral systems is that the differential immunogenicity of closely related proteins can be mimicked by short peptides which span the regions of sequence variation. To generalize this concept, we have studied the two Thy-1 proteins which vary by only a single amino acid. Chemically synthesized peptides differing in only one out of 19 amino acids were able to induce allospecific antisera. Thus, single amino acid changes have similar effects on the immunogenicity of proteins and small peptides, even though the latter are free from constraints provided by neighbouring structures in the tertiary configuration of the intact folded proteins.

Amino Acid Sequence↗
PubMedDate not supplied

The reactivity of anti-peptide antibodies is a function of the atomic mobility of sites in a protein.

To study the nature of antigenic recognition, antibodies have been prepared against a set of peptide sequences representing both highly mobile and well-ordered regions of myohaemerythrin, based on X-ray crystallographic temperature factors. Anti-peptide antibodies against highly mobile regions react strongly with the native protein; anti-peptide antibodies from well-ordered regions do not. Mobility is a major factor in the recognition of the native protein by anti-peptide antibodies; this may be of general significance in protein-protein interactions.

Animals↗
PubMedDate not supplied

Absence of Yq microdeletions in infertile men.

Microdeletions of the long arm of the Y chromosome (Yq) were described in men with idiopathic azoo- or oligozoospermia and seem to cause impairment of spermatogenesis. Deletion frequencies differ considerably among selected infertile men. The aim of this study was to investigate the prevalence of Yq microdeletions in patients with idiopathic infertility. Men with azoospermia or oligozoospermia resulting from endocrine or obstructive causes or with a constitutional cytogenetic anomaly were excluded. Ninety-seven patients presenting at infertility centers in Leipzig and Zurich were included in the study. Sixty-four (66%) of them were severely oligozoospermic (sperm concentrations < 5 x 10(6)/mL) and 33 (36%) were azoospermic. A sequence-tagged site (STS) PCR strategy was applied for the microdeletion screening. Thirteen STS markers spanning the whole euchromatic region of Yq were used. No Y-chromosomal microdeletion could be detected in these 97 infertile men. This result suggests a much lower Yq deletion frequency than previously thought, even among strictly selected patients with idiopathic azoo- or oligozoospermia.

Adolescent↗
PubMedDate not supplied

Utero-ovarian interaction in the regulation of reproductive function.

The physiological regulation of fertile reproductive cycle in mammals depends on interactions between hypothalamus-pituitary, ovarian and uterine stimuli. Over the past 20 years, much has been learned about the interrelation between the affluent and effluent lymph and vascular drainage in and around both ovarian and uterine tissues. An essential feature in the regulation of the fertile cycle is the functional status of the ovary, particularly the corpus luteum. During the time of implantation and the early pregnancy, an active corpus luteum is essential. As human chorionic gonadotrophin (HCG) is important in the maintenance of the corpus luteum, we investigated if it was produced by the cyclic endometrium. Immunohistochemical and in-situ hybridization reactions were performed but neither identified the presence of HCG during the proliferative phase. Positive staining and beta-human chorionic gonadotrophin (beta-HCG) mRNA were observed during the secretory phase in the glandular cells of the endometrium. The results were confirmed by Western blotting of secretory phase endometrium extracts and assessment of the functional secretory capacity of primary endometrial cultures. Polymerase chain reaction (PCR) investigations showed a positive result in the secretory phase. We postulate that, based on the very close morphological interrelation between the uterus and the ovary, the beta-HCG of the endometrium is the primary factor for the maintenance of the corpus luteum and early pregnancy.

Animals↗