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Biomedical subjects

A Albrecht

Publications and source records attributed to A Albrecht.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Doppler ultrasound in cases of Rhesus incompatibility. Effect of intravascular punctures with or without transfusion on feto-placental Doppler blood flow velocity curves].

OBJECTIVE: To investigate the influence of cordocentesis with or without blood transfusion on umbilical and fetal blood flow characteristics. METHODS: Of 42 pregnant women suffering from Rh. incompatibility 15 had a puncture of the umbilical cord for diagnostic reasons only. In 27 cases a total of 86 punctures was done for blood transfusion. Fetal heart rate, umbilical artery A/B Ratio and Pulsatility Index (PI) in the fetal aorta were measured before and after cordocentesis in all cases having or having not a transfusion. RESULTS: Diagnostic and therapeutic cordocentesis resulted in a slight decrease of peripheral resistance. Significant differences were only observed in cases with a haematocrit < 20% compared to cases with values > 40% or if the final haematocrit after transfusion resulted in a value of < 30%. CONCLUSION: The decrease peripheral resistance in cases of therapeutic cordocentesis can be attributed to the increase in blood volume and sufficient oxygenation of blood improving fetal perfusion. Doppler sonography is not helpful in the clinical management of red blood cell immunisation.

Adult↗
PubMed1996

Local cholinergic mechanisms mediate nitric oxide-dependent flow-induced vasorelaxation in vitro.

To determine whether local cholinergic mechanisms evoke nitric oxide (NO)-mediated flow-induced vasorelaxation, canine coronary artery rings without endothelium were suspended beneath an organ chamber that contained a stainless steel tube and a femoral artery segment with endothelium. The rings were superfused at a basal rate of 1 ml/min with physiological salt solution that was bubbled with 95% O2-5% CO2 and maintained at 37 degrees C. They were stretched to optimal length and contracted with prostaglandin F 2 alpha (2 x 10(-6) M). When flow through the stainless steel tube (direct superfusion) was increased from the basal rate of 1 to 4 ml/min, coronary force did not change. Superfusion of the rings (n = 8) with effluent from the femoral segment (endothelial superfusion) at 4 ml/min to study flow-induced vasodilation caused a 67.3 +/- 10.8% relaxation. Treatment of the segment with the NO synthase blocker NG-monomethyl-L-arginine (10(-4) M) eliminated the relaxation seen during endothelial superfusion (P < 0.05 vs. control). Application of atropine (10(-6) M) to additional femoral segments (n = 8) abolished the coronary relaxation observed during endothelial superfusion at 1 ml/ min, and the flow-induced relaxation observed at 4 ml/min was reduced from 64 +/- 8.3 to 27 +/- 5.6% (P < 0.05 vs. control). In studies on additional segments and rings (n = 6), the flow-induced relaxations at 4 ml/min of endothelial superfusion were blunted from 86 +/- 10 to 28 +/- 13% after the segments were treated with acetylcholinesterase (0.00028 U/min for 20 min). These data indicate that basal- and flow-induced release of NO from the vascular endothelium can be mediated by local cholinergic mechanisms. It is possible that flow causes acetylcholine release from certain endothelial cells, which stimulates NO release from these cells or from neighboring endothelial cells.

Acetylcholine↗
PubMed1995

Effects of hormone replacement therapy on growth hormone secretion patterns in correlation to somatometric parameters in healthy postmenopausal women.

OBJECTIVES: The aim of the present study was to investigate the influence of a continuous estrogen, cyclic progesterone replacement therapy on the secretion of growth hormone (GH) and IGF I as well as of somatometric-GH correlation patterns. METHODS: The study included 23 healthy postmenopausal women. Of the proband group 13 randomly selected women were treated with orally applicated 2 mg estradiol-valerat (E2V) and 10 mg dydrogesterone for 10 months. Ten women did not receive any hormonal treatment during this time. After 10 months all probands were reexamined and their GH and IGF I secretion, as well as their somatometric-hormonal correlation patterns, compared with those of a fertile control group. RESULTS: It could be shown, that in postmenopausal women a 10-month oral hormone replacement therapy led to a significant increase of GH- and IGF I levels, however, the treated postmenopausal women did not reach the levels of the fertile controls. Those women who did not receive any hormonal treatment and the postmenopausal women before HRT showed nearly identical GH- and IGF I levels as well as somatometric-GH correlation patterns. CONCLUSIONS: The results of the present paper indicate a marked influence of estrogens on GH and IGF I secretion. Furthermore, hormonal replacement therapy (HRT) may influence somatometric GH correlation patterns too.

Adult↗
PubMed1995

Hysterectomy increases the symptomatology of postmenopausal syndrome.

The purpose of our investigation was to verify whether or not women who have undergone hysterectomy react differently to the menopause compared with women who have not. The study was performed in a prospective documentation on 203 women, and the assessments of discomforts were provided by the patients themselves using questionnaires. For statistical purposes, the Mann-Whitney test and chi 2 test were used. In both groups of patients--with and without hysterectomy--a determination was made concerning the significance of differences in the degree of intensity of problems: breast tension (p < 0.05), muscle pains (p < 0.05), palpitations (p < 0.05) and dizziness (p < 0.01). Concerning the frequency of climacteric symptoms, a significant difference was noted for urogenital ailments. While only 29.6% of women who had not been operated on complained about discomfort caused by atrophy of the urogenital tract, the number of women with such discomfort who had had a hysterectomy was 42.6% (p < 0.01). In other words, women who underwent hysterectomy suffered more discomfort and showed frequent symptoms of urogenital atrophy.

Anxiety↗
PubMed1994

The mutator gene swi8 effects specific mutations in the mating-type region of Schizosaccharomyces pombe.

The swi8+ gene of Schizosaccharomyces pombe appears to be involved in the termination step of copy synthesis during mating-type (MT) switching. Mutations in swi8 confer a general mutator phenotype and, in particular, generate specific mutations in the MT region. Sequencing of the MT cassettes of the h90 swi8-137 mutant revealed three altered sites. One is situated at the switching (smt) signal adjacent to the H1 homology box of the expression locus mat1:1. It reduces the rate of MT switching. The alteration at the smt signal arose frequently in other h90 swi8 strains and is probably caused by gene conversion in which the sequence adjacent to the H1 box of mat2:2 is used as template. This change might be generated during the process of MT switching when hybrid DNA formation is anomalously extended into the more heterologous region flanking the H1 homology box. In addition to the gene conversion at mat1:1, two mutations were found in the H3 homology boxes of the silent cassettes mat2:2 and mat3:3.

Base Sequence↗
PubMed1994

Absorption of orally supplied natural estrogens correlated with age and somatometric parameters.

The plasma levels of estradiol were studied in 20 postmenopausal women over a period of 8 h following the ingestion of a single dose of 2 mg estradiol valerate and 2 mg micronized estradiol. The determined plasma estradiol concentrations were correlated with somatometric characteristics and age. Twenty-six postcephalic body measurements, the body weight and six skin-fold thickness measurements were taken and the body mass index computed; estradiol serum concentration was measured before and after administration of micronized estradiol and estradiol valerate, respectively. It was shown that estradiol concentrations obtained after estradiol valerate and micronized estradiol ingestion were dependent on the patient's age as well as on the constitutional type. Additionally, we found that there were differences in the reachable estradiol plasma concentrations following the application of the two preparations. Our results justify the individual and differentiated estrogen replacement therapy of the postmenopausal woman.

Administration, Oral↗
PubMed1993

A simple and inexpensive high density dialysis tubing cell culture system for the in vitro production of monoclonal antibodies in high concentration.

This paper describes the construction and application of a low-cost roller bottle-like culture appliance in which hybridoma cells can be cultivated in high density in dialysis tubing. The appliance facilitates the simultaneous culture of up to four cell lines yielding 50 ml culture volume of each. Samples for follow-up analysis of the cultures can easily be taken when needed through sample ports. In order to obtain high cell densities (at least 10(7) cells/ml), high cell viability (at least 50%) and high antibody yield (at least 1.0 mg/ml) the bottle is rolled at a speed of 4-6 rpm and is gassed continuously by a micropump driven by rechargeable NiCd batteries fixed to the culture flask. Depending on the individual properties of the hybridoma lines tested, the cells may be cultured for 1-2 weeks, and cell densities of up to 30 x 10(6) cells/ml with viabilities of approximately 50% and monoclonal antibodies in concentrations of up to 2.8 mg/ml may be obtained. In their properties the monoclonal antibodies produced by this in vitro procedure are indistinguishable from those prepared in the form of conventional stationary culture supernatant or of ascitic fluid. Specific antibody content is within the same range as in ascitic fluid. Consequently, the monoclonal antibodies can be purified in one step, e.g., by ion exchange chromatography from the culture supernatant. Therefore, the newly developed culture device and the culture method described is a useful alternative to ascites production in live mice.

Animals↗
PubMed1993

[Mediastinal chloroma with right heart involvement. Unusual cause of a superior vena cava syndrome].

For four months a 28-year-old man had been suffering from a sensation of pressure in his head when lying down, swelling of the face, exertional dyspnoea and weight gain of 9 kg. Biochemical tests and chest radiograph were unremarkable. Echocardiography revealed a 3 x 5 cm mass in the right atrium, extending into the superior vena cava whose lumen was narrowed to a few millimetres. Computed tomography and magnetic resonance imaging were suggestive of a malignant tumour. Bone marrow biopsy as well as transvascular and mediastinoscopically obtained biopsies failed to provide a pathological diagnosis. Exploratory thoracotomy uncovered a nonresectable chloroma surrounding both venae cavae. It had penetrated into the right and left atria, as well as the pulmonary veins. A Gore-tex bypass was placed between the innominate vein and right atrial appendage. The tumour was identified as a local manifestation of acute myeloid leukaemia. Treatment with idarubicin (12 mg/m2 daily for 3 days) and adriamycin (1.5 mg/m2 daily for 4 days) followed by radiotherapy with 35 Gy achieved partial remission and 15 months after onset of treatment the patient is in a good general condition.

Adult↗
PubMed1993

An automatic dehydrogenase-based flow-injection system: application for the continuous determination of glucose and lactate in mammalian cell-cultures.

A concept for the development of an automatic flow-injection analyzer with integrated dehydrogenase columns and its application in the control of industrial processes is presented. The system is based upon a kernel consisting of a nested-loop injection unit, pumps for the filling of the injection loops and the transport of buffer and values for switching on the one hand between sample and standard solutions and on the other hand between different enzyme columns. A Microsoft Windows 3.x application 'WIN-FIA' controls interactively the whole system and can be easily adapted to a specific solution of an analytical problem. As an example, the flow-injection system was used for the continuous determination of glucose and lactate, using glucose dehydrogenase (GDH) and lactate dehydrogenase (LDH) as indicator enzymes, in a mammalian cell-culture fermentation process. The resulting concentration values are in good agreement with those obtained by discontinuously taken standard spectrophotometric enzyme assays.

Animals↗
PubMed1993

Intestinal vitamin A metabolism: coordinate distribution of enzymes and CRBP(II).

In the mucosal layer of the small intestine, we found nearly identical gradients of CRBP(II), retinal reductase, and LRAT levels down the duodenal-ileal axis, suggesting coordinate regulation of these three proteins. In all cases the level of binding protein or enzyme activity was greatest in the proximal intestine and then decreased sharply in the distal half. This pattern fits with the known capacity of the intestine to absorb vitamin A. In addition, the retinal reductase activity was found predominantly in the intestinal mucosa, while LRAT activity was found in both the intestinal mucosa and muscle. An even distribution of LRAT activity along the longitudinal axis of the intestinal muscle was consistent with an even distribution of CRBP in that tissue. In conjunction with LRAT activity and CRBP, we found endogenous retinyl ester stores in the intestinal muscle layer. The patterns of retinyl ester produced by LRAT in vitro and found in vivo were similar, with retinyl palmitate predominating and a high percentage comprised of retinyl stearate. We also observed a bile salt-independent retinyl ester hydrolase activity in intestinal muscle whose distribution paralleled the retinyl ester stores and LRAT levels. This hydrolase appears to be distinct from retinyl ester hydrolases described from other organs as its activity was insensitive to retinyl ester chain length, the presence of bile salts, or the addition of apo-CRBP. This activity was inhibited by diethyl-p-nitrophenyl-phosphate (IC50 100 microM) and diethylpyrocarbonate (IC50 10 microM), demonstrating a requirement for active serine and histidine residues. In addition, we describe an activity present in some intestinal microsomal preparations that can perturb determinations of reductase and LRAT activity and must be avoided.

Acyltransferases↗