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Biomedical subjects

B Scholz

Publications and source records attributed to B Scholz.

At least 19 recordsLinked to original sources
PubMed1995

The separation of overlapping neuromagnetic sources in first and second somatosensory cortices.

In response to a somatosensory stimulus, two cortical centers in each hemisphere produce neural mass activity large enough to be detected with electric (EEG) or magnetic (MEG) measurements. Both the primary somatosensory cortex (S-I), located in the postcentral sulcus and in the depths of the central sulcus, as well as the secondary somatic sensory cortex (S-II), lying in the upper bank of the Sylvian fissure, respond within the first 100 ms such that the two activities overlap in time. We demonstrate that this overlap can be disentangled using a MUSIC-type approach, as suggested by Oppelt and Scholz. It needs no a priori information about the sources. As the results show, there are several instances in time in which only one of the two centers (SI, SII) is active. It is only for these time segments that a single moving dipole yields meaningful results. Such time intervals occur during the upstroke of the late component around 60 ms (only SI activity) and during the down-stroke around 120 ms (only SII activity). In these time intervals the activity of one of the somatosensory areas is still large enough, while the other center is not yet or is no longer active.

Adult↗
PubMed1992

Recombination between adenovirus type 12 DNA and a hamster preinsertion sequence in a cell-free system. Patch homologies and fractionation of nuclear extracts.

We have previously described a cell-free recombination system derived from hamster cell nuclear extracts in which the in vitro recombination between a hamster preinsertion sequence, the cloned 1768 base-pair p7 fragment, and adenovirus type 12 (Ad12) DNA has been demonstrated. The nuclear extracts have now been subfractionated by gel filtration on a Sephacryl S-300 column. The activity promoting cell-free recombination elutes from the Sephacryl S-300 matrix with the shoulder and not the peak fractions of the absorbancy profile. By using these protein subfractions, in vitro recombinants have been generated between the p7 preinsertion sequence and the 60 to 70 map unit fragment of Ad12 DNA, which has previously shown high recombination frequency. In all of the analyzed recombinants thus produced in vitro, striking patchy homologies have been observed between the p7 and Ad12 junction sequences, and between Ad12 DNA or p7 DNA and pBR322 DNA. The patchy homologies are similar to those found earlier during the analyses of some of the junction sequences in integrated Ad12 genomes in Ad12-induced hamster tumor cell lines. Proteins in the shoulder fractions of the gel-filtration experiment can form specific complexes with double-stranded synthetic oligodeoxyribonucleotides corresponding to several p7 and Ad12 DNA sequences. These sequences participate in the recombination reactions catalyzed by the same column fractions in the shoulder of the absorbancy profile. Such proteins have not been found in the peak fractions. Further work will be required to ascertain that the cell-free recombination system mimics certain elements of the mechanisms of integrative recombination and to purify the cellular components essential for recombination.

Adenoviridae↗
PubMed1992

Platelet-induced thrombin generation time: a new sensitive global assay for platelet function and coagulation. Method and first results.

A new sensitive test--platelet-induced thrombin generation time (PITT)--is described, in which the formation of thrombin in partially anticoagulated platelet-rich plasma (PRP) leads to aggregation immediately followed by coagulation of PRP. 0.6 ml PRP are rotated in a disk-shaped cuvette within the light beam of a photometer. In PITT, platelets stick to the cuvette wall and, mediated by a large PRP/surface/air interface at the cuvette wall, are activated and participate in thrombin formation which leads to aggregation and clotting. The times from onset of rotation until aggregation (Ta) and until coagulation (Tc) of the PRP samples are recorded. PITT was very sensitive and detected low concentrations of unfractionated heparin (0.01 IU/ml) in vitro. PITT parameters were significantly prolonged ex vivo 2 h after oral administration of acetylsalicylic acid (0.5 g) and after single subcutaneous injections of heparin (5,000 IU). Patients receiving phenprocoumon prophylaxis had markedly prolonged Ta and Tc values (longer than 20 min, n = 23). Patients with recent thrombotic episodes had markedly shorter values than healthy volunteers. PITT may become a very sensitive global test to detect mild hemorrhagic disorders, to monitor the effects of antithrombotic drugs and to detect patients with a risk of vascular occlusions.

Adult↗
PubMed1992

[Neurohistological findings in the parietal cortex of children with chromosome aberrations].

In Golgi-Cox impregnated parietal cortex (regio postcentralis) of two children (20 months of age or 6 years of age) with Down's syndrome the pyramidal neurons of lamina III and V were investigated qualitatively and quantitatively. Fives types of pyramidal neurons were classified and compared statistically. As parameters for characterizing pyramidal neurons served dendritic lengths for all dendritic orders, within single dendritic fields, in apical and basal parts of the dendritic tree, and of the whole neuron. Normal values obtained in brains of the same age were not available, therefore, we compared our results with those published by other authors. To study the developmental stage of the pyramidal neurons in both our cases, we compared analogue pyramid types in both brains. The pyramidal neurons showed different qualitative abnormalities in their dendritic tree configuration. The comparison of quantitative parameters suggests the pyramidal cells of the older child show more degenerative changes, concerning especially lamina III pyramids but in lamina V pyramids as well. These changes might be structural correlates of the mental retardation: the 6 year old child was strongly retarded in clinical symptoms, too. The results are discussed and critically evaluated in view of the clinical signs of Morbus Down. Finally we should await the investigations of more cases for demonstrating the normal as well as the abnormal development of the human cerebral cortex.

Child↗
PubMed1990

Increased brain uptake of gamma-aminobutyric acid in a rabbit model of hepatic encephalopathy.

Transfer of the inhibitory neurotransmitter gamma-aminobutyric acid across the normal blood-brain barrier is minimal. One prerequisite for gamma-aminobutyric acid in plasma contributing to the neural inhibition of hepatic encephalopathy would be that increased transfer of gamma-aminobutyric acid across the blood-brain barrier occurs in liver failure. The aim of the present study was to determine if brain gamma-aminobutyric acid uptake is increased in rabbits with stage II-III (precoma) hepatic encephalopathy due to galactosamine-induced fulminant hepatic failure. A modification of the Oldendorf intracarotid artery-injection technique was applied. [3H] gamma-aminobutyric acid, [14C] butanol, and 113mIn-labeled serum protein (transferrin) were injected simultaneously 4 s before decapitation. The ipsilateral brain uptake index of gamma-aminobutyric acid was determined from measurements of the 3 isotopes in 5 brain regions. Uncorrected or simple brain uptake indices of [3H] gamma-aminobutyric acid and [113mIn] transferrin were calculated using [14C] butanol as the highly extracted reference compound. The [113mIn] transferrin data were also used to "correct" the brain uptake index of [3H] gamma-aminobutyric acid for intravascular retention of [3H] gamma-aminobutyric acid. The methodology adopted minimized problems attributable to rapid [3H] gamma-aminobutyric acid metabolism, and slow brain washout and recirculation of the radiolabeled tracers. Both the uncorrected and corrected brain uptake indices of gamma-aminobutyric acid as well as the simple brain uptake index of transferrin were significantly increased in both stage II and III hepatic encephalopathy in all brain regions studied. Moreover, these brain uptake indices were significantly greater in stage III hepatic encephalopathy than in stage II hepatic encephalopathy. These findings indicate that transfer of gamma-aminobutyric acid from plasma to brain extracellular fluid is increased in the model of hepatic encephalopathy studied; hence, they provide support for the hypothesis that plasma-derived gamma-aminobutyric acid may contribute to the neural inhibition of hepatic encephalopathy due to fulminant hepatic failure.

Animals↗
PubMed1988

[Release of estrogen-induced positive feedback in the follicular phase].

Influence of estradiol on the secretion of pituitary gonadotropins in a sense of positive feedback in formating not until the progress of development of puberty. Appearance of positive feedback mechanism, which cause the secretion of LH and FSH reason of increasing estrogen doses, induces menstrual cycle. In 10 healthy, normally menstruating women plasma LH and FSH have been measured before and every 12 hours after an intramuscular injection of 50 micrograms estradiol benzoate per kg body weight. A positive feedback could be observed between the 5th and 14th day of the menstrual cycle. At first the LH-concentration decreased and then after 36-48 hours estradiol benzoate injection induced an increase of LH.

Adult↗
PubMed1987

The modulating effect of estrogens on luteinizing hormone release in complete androgen insensitivity syndrome before and after gonadectomy and cyclic steroid application.

The response of LH release to exogenous estrogens was studied in three patients with androgen insensitivity syndrome (AIS) before and after gonadectomy and a prolonged treatment with a sequential pill. Estrogen provocation tests were performed in which 0.05 mg/kg body weight estradiol benzoate was administered intramuscularly and serum FSH and LH levels were assessed every 12 hours for 96 hours after gonadectomy, three months after a prolonged treatment with a sequential pill (16 cycles: 9 days mestranol 100 micrograms, 12 days mestranol 80 micrograms and chlormadinone acetate 2 mg) and in one patient before gonadectomy. The control group consisted of 10 normal females during the follicular phase. A positive feedback effect was induced in normal females and in AIS patients after prolonged treatment with a sequential pill.

Adolescent↗
PubMed1987

[Can changes in the gonadotropin response in androgen insensitivity syndrome be detected with the GnRH test following gonadectomy and steroid administration?].

Information about the reaction of the hypothalamic pituitary axis by Gn-Rh-stimulation dependent from gonadectomy and steroid substitution in 3 patients with androgen insensitivity syndrome. The test was done before and after gonadectomy, under receipt of within the intake of a sequential hormonal contraceptive (Sequenz-Ovosiston) in the 16th cycle and after a pill free interval of 3 months, LH and FSH were estimated with a RIA-method. The LH-base-concentration is independent from the moment of the gonadectomy normogonadotrop and indicate after Gn-Rh-stimulation a regular LH-answer. The FSH-reaction is clearly dependent from the moment of gonadectomy. Not the gonadectomy but the steroid substitution over a long time is decisive about the reaction of the adenohypophysis.

Adolescent↗
PubMed1986

Organization of the thymidylate synthase gene of herpesvirus saimiri.

Herpesvirus saimiri codes, unlike most other herpesviruses, for a thymidylate synthase (TS). The TS gene of herpesvirus saimiri is unusual in structure and regulation of expression. It is transcribed into a nonspliced mRNA of 2,190 nucleotides. The single open reading frame of the viral TS gene, instructing a polypeptide of 33.5 kilodaltons, has extensive sequence homology with the corresponding TS coding sequences of human cells and of various procaryotes; the putative polypeptide derived from the nucleotide sequence of the herpesvirus saimiri TS gene is 70% identical with the human enzyme. The untranslated regions of the herpesvirus saimiri TS gene do not share homology with the other characterized eucaryotic or bacterial TS genes. The 5' untranslated sequence has 22 ATG triplets shortly followed by stop codons. The herpesvirus saimiri TS gene, which may be weakly transcribed during immediate early and early times of virus replication, is maximally expressed at the late phase. Various parameters suggest that the TS gene has been acquired in virus evolution by an ancestral herpesvirus from the cellular genome.

Amino Acid Sequence↗
PubMed1981

[Sexual development -- sexual advice -- sexual education -- Paedagogico-psychological aspects in gynaecological practice (author's transl)].

Sexuality of man is conceived as a psycho-physical phenomenon, and in gynaecological practice particular attention must be given to psychogenic components, whenever it comes to disorders of sexual organs and functions. It is also desirable and necessary to attend to patients not only in terms of medical findings and their communication. They also should be offered advice and recommendations. Fears and anxiety should be taken from them regarding their own sexual behaviour and experience and partnership relations. Findings obtained from empirical studies into sexual development together with results of an analysis of expectations and attitudes of gynaecological patients. -- Recommendations are given on how to brief patients, with particular reference being made to group briefing. -- Conclusions are suggested for training and upgrading of gynaecologists under the auspices of the Society of Gynaecology and Obstetrics.

Adolescent↗
PubMed1979

[Common antigen for serological detection of urinary tract infections during pregnancy (author's transl)].

All urinary tract infections cannot be safely detected by bacterial urine testing during pregnancy. Therefore, the question was studied whether detection of antibody to the "enterobacterial common antigen" (ECA) might be important to screening of pregnant women for urinary tract infections. Tests were applied to 202 sera obtained from 42 pregnant women with urinary tract infection, with pathological titres having been recorded from 21.8 per cent.--Detection of antibody to ECA, consequently, is not believed to be helpful in improving diagnosis of urinary tract infections during pregnancy.

Antigens, Bacterial↗
PubMed1977

[Demonstration of antibody-coated bacteria in the urine of pregnant women].

Urinary sediments of 64 pregnant women with significant bacteriuria which has been demonstrated several times before, have been investigated for the presence of antibody coated bacteria. Antibody titers were determined in the corresponding serum samples in addition and the results were compared with the clinical diagnosis. In 50% of pregnant women with pyelonephritis antibody coated bacteria could be demonstrated, while 60% of them had elevated serum titers. Taking into account both results in 80% of the pregnant women the clinical diagnosis of pyelonephritis could be confirmed. Pregnant women with asymptomatically significant bacteriuria never gave positive results, whereas pregnant women with cystitis mainly did have negative results. The demonstration of antibody coated bacteria in the urinary sediments of pregnant women with significant bacteriuria as well as the detection of elevated serum antibody titers with the indirect immunofluorescence technique against the urinary strain were found to be of importance for the valuation of a significant bacteriuria.

Antibodies, Bacterial↗