Biomedical subjects

W Schmidt

Publications and source records attributed to W Schmidt.

At least 379 records · Page 21Linked to original sources

PubMed1991

[Doppler ultrasonography--perinatal data in cases with end-diastolic block and reverse flow].

In 50 cases with an end-diastolic zero flow or reverse flow all antenatal and perinatal abnormalities have been recorded. The fetal outcome was registered. The percentage of highly dystrophic newborns (percentile less than 5) was 88%. The perinatal mortality counted up to 16% and the percentage of congenital malformations (including chromosomal anomalies) was 12%. A reverse flow was registered in 4 cases. The perinatal mortality of those cases with reverse flow was 100%. In approx. one-quarter of those pregnancies and in 50% of the perinatally deceased newborns, there were no pathological or suspicious changes in the antepartal and/or subpartal CTG-recordings. The Duplex sonographical diagnosis of an end-diastolic zero flow/reverse flow, has a highly positive predictive value, whereas its sensitivity is low. It can be regarded as a very helpful parameter in clinical diagnosis, particularly as it is independent of borderline values. The correct choice of the high-pass wall filter (50-100 Hz) is important.

Adult↗

PubMed1991

Measurement of rat brain kynurenine aminotransferase at physiological kynurenine concentrations.

The production of the neuroinhibitory and neuroprotective metabolite kynurenic acid (KYNA) was investigated in rat brain by examining its biosynthetic enzyme, kynurenine aminotransferase (KAT). By using physiological (low micromolar) concentrations of the substrate L-kynurenine (KYN) and by determining the irreversible conversion of [3H]KYN to [3H]KYNA as a measure of KAT activity, a novel, simple, and sensitive assay was developed which permitted the detailed characterization of the enzyme. Only a single protein, which under routine assay conditions showed approximately equal activity with 2-oxoglutarate and pyruvate as the aminoacceptor, was found in rat brain. The enzyme was distributed heterogeneously between the nine brain regions studied, with the KAT-rich olfactory bulb displaying approximately five times higher activity than the cerebellum, the area with lowest KAT activity. In subcellular fractionation studies, the majority of KAT was recovered in mitochondria. In contrast to many known aminotransferases, partially purified KAT was shown to be highly substrate-specific. Thus, of the amino acids tested, only alpha-aminoadipate and tryptophan displayed moderate competition with KYN. Notably, 3-hydroxykynurenine, reportedly a very good substrate of KAT, competed rather poorly with KYN as well. Aminooxyacetic acid, a nonspecific transaminase inhibitor, blocked KAT activity with an apparent Ki of 5 microM. Kinetic analyses with partially purified rat brain KAT revealed a Km of 17 microM for KYN with 1 mM 2-oxoglutarate, but a much higher Km (910 microM) with 1 mM pyruvate. Km values for 2-oxoglutarate and pyruvate were 150 and 160 microM, respectively. The cellular localization of KAT was examined in striatal homogenates obtained from rats 7 days after an intrastriatal injection of quinolinate.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMed1991

Trauma in cirrhosis: an indicator of the pattern of alcohol abuse in different societies.

While some morbidities associated with the excessive use of alcohol are related to the total amount of alcohol consumed--cirrhosis being an example--other pathologies, such as trauma and those of psycho-social origin, are mainly related to the frequency of acute alcoholic intoxication rather than to the total amount consumed. The balance between these two types of alcohol-associated morbidities can provide an indication of the relative frequency of intoxication, and thus of the pattern of alcohol abuse in a population. Since trauma is highly associated with acute alcoholic intoxication, the prevalence of bone fractures was determined in cirrhotics in nine countries. The prevalence of rib and vertebral fractures on routine chest x-rays showed a 17-fold variation in the different countries, from 2% and 6% in Spain and Italy to 30% and 34% in Canada and the USA, suggesting marked differences in the pattern of alcohol abuse to intoxication. Conversely, the prevalence of cirrhosis is twice as high in Spain and Italy than in Canada and the USA. A strong positive correlation between per capita consumption and cirrhosis mortality (r = 0.86; p less than 0.01) exists among the nine countries studied, while the correlation between per capita alcohol consumption and the prevalence of trauma is not statistically significant (r = 0.40). Supporting a strong association between trauma and alcoholic intoxication, the prevalence of trauma was found to be highly correlated: r = 0.88, p less than 0.002, with the degree of concern for the psycho-social consequences of alcohol abuse in the different countries. Data indicate that trauma can be used as an objective indicator to assess the pattern of alcohol abuse in a population.

Alcohol Drinking↗

PubMed1991

Evidence against leukotrienes as mediators of brain edema.

Leukotrienes are powerful metabolites of arachidonic acid which are known to increase the permeability of peripheral blood vessels. These substances are found in brain tissue in association with cerebral ischemia, and in brain tumors. Therefore, it has been proposed that leukotrienes have a mediator function in brain edema. This hypothesis was subjected to further experimental analysis in this study, in which the authors investigated whether: 1) superfusion of the exposed brain surface with leukotrienes increases the permeability of extraparenchymal blood vessels in vivo; 2) intraparenchymal infusion of leukotrienes induces brain edema; and 3) pharmacological inhibition of leukotriene formation by BW755C, an inhibitor of leukotriene synthesis, reduces formation of brain edema from a standardized traumatic insult. The pial vessels of the parietal cortex of cats were examined by fluorescence microscopy during cerebral superfusion with the leukotrienes C4 (LTC4), D4 (LTD4), or E4 (LTE4) by using an open cranial window preparation. Intravenous Na(+)-fluorescein served as an in vivo blood-brain barrier (BBB) indicator. Superfusion of the pia with leukotrienes (up to 2 microM) did not open the barrier to fluorescein, but was associated with a significant constriction (up to 25%) of arterial and venous vessels. In experiments with slow infusion of leukotriene B4 (LTB4) or LTC4 into the white matter of feline brain, the tissue water content was subsequently determined in serial brain slices using the specific gravity method. Tissue water profiles obtained after a 15-microM infusion of either LTB4 or LTC4 were virtually identical with those of control animals infused with mock cerebrospinal fluid. Thus, neither LTB4 nor LTC4 led to an augmentation of infusion-induced brain edema. In a final series, a cold lesion of the left parietal cortex was induced in rabbits. Twenty-four hours later, swelling of the exposed hemisphere was quantified by gravimetrical comparison of its weight with that of the contralateral nontraumatized hemisphere. Eight animals received BW755C intravenously prior to and after trauma to inhibit formation of leukotrienes. Seven rabbits were infused with an equivalent volume of saline as a control study. The resulting hemispheric swelling was 7.7% +/- 0.6% (mean +/- standard error of the mean) 24 hours later in animals receiving BW755C and 7.8% +/- 1.2% in the control group, indicating that inhibition of leukotrienes was ineffective in preventing formation of vasogenic brain edema. The findings demonstrate that leukotrienes administered to the brain in concentrations occurring under pathological conditions do not open the BBB nor do they induce brain edema.(ABSTRACT TRUNCATED AT 400 WORDS)

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗

PubMed1991

[Histochemical study of carbohydrate metabolism in fetal membranes].

By means of histochemical methods, we investigated the location of carbohydrates and the carbohydrate metabolism in the fetal membranes. It was shown that the often extremely intense vacuolisation of the trophoblast cells is based on the excessive accumulation of glycogen. Perhaps the reason, that glycogen could not be shown up to now, is that it lies in an undetectable state. From our enzyme histochemical results, we conclude that out of glycogen, lipids, phospholipids, also mucopolysaccharides and collagen for the extracellular matrix are synthetized. Furthermore we assumed, that glycogen is partly depolymerized and transported towards the amniotic epithelial with a liquid flow. After uptake by the fibroblasts, it is used for the further production of extracellular matrix. The carbohydrate component of glycoproteins and proteoglycans were classified by the use of lectin-binding-studies. The amniotic epithelial cell does not only release glycoproteins and proteoglycans on the apical cell surface but also into the intercellular space. These substances are probably related to the intercellular liquid flow. 3H-labelled glucose passed through this intercellular space and transcellular through the amniotic epithelium.

Alcian Blue↗

PubMed1991

[Technique and complications of microvascular reanastomosis].

We describe 193 free tissue transfers for routine indications and for the solution of difficult problems. Some complex venous anastomoses are illustrated. The complete loss of a transplant is the most important complication of free tissue transfer. In most cases it is due to a thrombosis of the venous microanastomosis.

Anastomosis, Surgical↗

PubMed1991

[Clinical use of microvascular reanastomosed transplants].

We report 155 free jejunal transplants carried out since August 1984. The complications and the indications for the use of free intestinal transplants in the reconstruction of defects of the oral cavity and pharynx are recorded. Also we report the use of the revascularised latissimus dorsi myocutaneous flap and the fascicutaneous radial forearm flap in head and neck reconstruction.

Anastomosis, Surgical↗

PubMed1991

[Modification of the microvascular reanastomosed latissimus dorsi flap for reconstruction after extensive maxillary resection].

Large defects after extended maxillectomy and orbital exenteration were immediately reconstructed using a modification of the revascularized musculocutaneous latissimus dorsi flap. Three skin islands were transplanted based on the muscular part of the flap. The first island replaced the hard palate, the second the lateral nasal wall and the third was used together with the preserved eyelids to reconstruct an eye socket. The muscular part of the flap was folded spirally so that each skin island reached the site to be reconstructed.

Anastomosis, Surgical↗

PubMed1991

[The properties and potential uses of the trimesic acid dosimeter].

The trimesic acid dosimeter developed by Matthews is extremely sensitive to ionizing radiation. Tests on the characteristics of this detector show two serious differences to the Fricke dosimeter. With trimesic acid (1, 3, 5-benzentricarboacid) absorbed doses can be detected which are 1000 times smaller than with the Fricke solution. The radiochemical turnover here, as opposed to the Fricke dosimeter, is dependent on the dose rate up to 2.2 Gy/min. With high dose rates the trimesic acid dosimeter is well suitable for thin-layer dosimetry. For example in front of metallic scattering bodies (Al, Ti, Cu, Mo, Ag, W, Pb) exposed to cobalt-60-gamma, 9- and 15-MV bremsstrahlung and electron radiation with initial energies of 6.0, 8.0, 10.0 and 19.45 MeV the back scatter radiation can be measured easily.

Cobalt Radioisotopes↗

PubMed1990

Adipose conversion of 3T3-L1 cells in a serum-free culture system depends on epidermal growth factor, insulin-like growth factor I, corticosterone, and cyclic AMP.

A culture system for 3T3-L1 preadipocytes based on a serum-free chemically defined medium containing fetuin, transferrin, and pantothenate is described. In this system, adipose conversion depends on the following conditions. 1) In the presence of high insulin concentrations (1 microM), addition of corticosterone together with 1-methyl-3-isobutylxanthine (MIX) for not more than the first 4 days after confluence to the culture medium induces maximal adipose conversion within 12-14 days. MIX may be replaced by forskolin or permeable analogues of cAMP, indicating that its effect is due to elevated cellular cAMP levels. 2) At low insulin concentrations (1 nM), adipose conversion is reduced. Growth hormone or insulin-like growth factor I together with epidermal growth factor have to be present as a medium supplement together with corticosterone and MIX to get maximal adipose conversion. 3) The induction of adipose conversion by corticosterone and MIX in the presence of either high insulin concentrations or insulin-like growth factor I together with epidermal growth factor is accompanied by post-confluent mitoses. Inhibitors of DNA replication markedly reduce adipose conversion. Fibroblast growth factor and platelet-derived growth factor, although acting as potent mitogens on 3T3-L1 cells, do not support adipose conversion induced by corticosterone and MIX.

1-Methyl-3-isobutylxanthine↗

PubMed1990

[Hepatitis B vaccination in nursing personnel. Experiences in an institute for mentally handicapped].

Vaccination of nursing staff against hepatitis B proved successful. Seroconversion was achieved in about 96 per cent after only three injections. This population has a high risk of contracting hepatitis B infections. After primary vaccination further injections were given to non-responders and law-responders. In these cases 50 per cent developed protective antibody-titers after a fourth injection. Booster injections often raised the titers to higher levels than did the primary injections.

Adult↗

PubMed1990

The effect of various steroid treatment regimens on cold-induced brain swelling.

The role of steroid therapy in brain oedema following acute cerebral lesions is still unsolved. This study was conducted to compare the efficacy of dexamethasone and triamcinolone, and to analyze the influence of timing and duration of treatment on cold-induced brain swelling. In rabbits, a cryogenic lesion of the left parietal cortex was induced. 24, or 48 hrs after trauma, hemispheric swelling, water- and electrolyte-contents were measured. A first series of animals received dexamethasone, triamcinolone or saline for 24 hrs, starting treatment 10 min after trauma. In a second series, steroid treatment lasted 48 hrs and in a third series the animals were additionally pretreated for 24 hrs. Dexamethasone and triamcinolone slightly decreased posttraumatic hemispheric swelling, from 7.7% in controls to 7.0% in treated animals. There was no significant difference between dexamethasone and triamcinolone. Reduction of swelling was most pronounced in animals with 48 hrs treatment. Pretreatment with steroids was not superior to early posttraumatic treatment. On the other hand, dexamethasone and triamcinolone significantly decreased cerebral water content in the traumatized and contralateral hemisphere, as well as in non-traumatized animals. The unspecific reduction of water content by steroids in rabbits might explain the moderate therapeutical effect on brain swelling. This effect might be beneficial, nevertheless, with respect to an improvement of the intracranial compliance.

Animals↗

PubMed1990

Atrial natriuretic peptide during and after maximal and submaximal exercise under normoxic and hypoxic conditions.

The present study was designed to investigate the influence of exercise intensity and duration as well as of inspiratory oxygen content on plasma atrial natriuretic peptide concentration [( ANP]) and furthermore to compare ANP with the effect on aldosterone concentration [( Aldo]). Ten untrained male subjects performed a maximal exercise test (ME) on a cycle ergometer and a submaximal test of 60-min duration at 60% of maximal performance (SE) under normoxia (N) and normobaric hypoxia (H) (partial pressure of oxygen: 12.3 kPa). Five subjects were exposed to hypoxia at rest for 90 min. The [ANP] was mostly affected by exercise intensity (5 min after ME-N, +298.1%, SEM 39.1%) and less by exercise duration (at the end of SE-N: +229.5%, SEM 33.2%). Hypoxia had no effect at rest and reduced the exercise response (ME-H, +184.3%, SEM 27.2%; SE-H, +172.4%, SEM 15.7%). In contrast to ANP, the Aldo response was affected more by duration at submaximal level (+290.1%, SEM 34.0%) than by short maximal exercise (+235.7%, SEM 22.2%). Exposure to hypoxia rapidly decreased [Aldo] (-28.5%, SEM 3.7% after 30 min, P less than 0.01), but did not influence the exercise effects (ME-H, +206.2%, SEM 26.4%; SE-H, +321.6%, SEM 51.6%). The [ANP] increase was faster than that of [Aldo] during the maximal tests and there was no difference during submaximal exercise. Changes in plasma volume (PV), sodium concentration, and osmolality (Osm) were most pronounced during maximal exercise (for ME-N: PV -13.1%, SD 3.6%, sodium +6.2 mmol.l-1, SD 2.7, Osm +18.4 mosmol.kg H2O-1, SD 6.5). Regression analysis showed high correlations between changes in [ANP] and in Osm during and after maximal exercise and between changes in [ANP] and heart rate for submaximal exercise. It is concluded that besides other mechanisms increased Osm might be involved in the exercise-dependent increase of plasma [ANP].

Adult↗

PubMed1990

Hepatic encephalopathy influences high-affinity uptake of transmitter glutamate and aspartate into the hippocampal formation.

The present work was carried out to study the influence of ammonia and factors from sera and cerebrospinal fluid (CSF) from patients with different degrees of chronic liver diseases on [3H]D-aspartate (Asp) and [3H]L-glutamate (Glu) high-affinity uptake into the rat hippocampal formation. For comparison, high-affinity uptake of Glu and Asp was determined in human hippocampal brain tissue obtained at autopsy from cirrhotic patients dying in hepatic coma and from control brains free from neurological, psychiatric, or hepatic diseases. Sera and CSF from patients with chronic liver failure and hepatic encephalopathy (HE) were seen to reduce dramatically Glu and Asp uptake into rat hippocampal dendritic layers. A close inverse relationship was found to exist between the level of ammonia in the sera and the inhibition of uptake, both phenomena correlating highly with the extent of liver failure. The present findings, obtained after dilution of sera from patients with HE while maintaining initial ammonium levels, elucidate, however, that ammonia alone cannot account for the reduction in Glu/Asp uptake capacity. The inhibition of Asp uptake into human hippocampal formation of patients dying in hepatic coma was even more pronounced when compared to that found in rat hippocampus incubated in sera and CSF from patients. Glu/Asp uptake into brain tissue is supposed to be an important factor in the pathogenesis of HE accompanying liver dysfunctions.

Adult↗

PubMed1990

Quinolinate neurotoxicity and glutamatergic structures.

Neurotoxic properties of quinolinic acid following intracerebroventricular application were investigated in the hippocampal formation of 12- and 30-day-old rats. Quinolinic acid neurodegenerative potency was found to depend on the survival time, the dose applied and the developmental stage of the animal. Pretreatment with kynurenic acid and ketamine as well as the transection of the perforant path were noted to protect major parts of the hippocampal cell layers from quinolinic acid-induced degenerative effects. The results are interpreted in view of a putative dependence of quinolinic acid neurotoxicity on the presence of established synaptic, in particular glutamatergic, processes which play a major role in the hippocampal formation and mature during the first postnatal weeks. For comparison, we studied local effects of quinolinic acid on superior cervical and dorsal root ganglia in which glutamate inputs obviously do not occur; no signs of neuronal vulnerability were seen.

Age Factors↗

PubMed1990

A radiological analysis of uncemented PCA tibial implants with a follow-up period of 4-7 years.

A total of 63 uncemented PCA tibial implants were followed radiologically for a period of 4-7 years to establish whether primary fit, alignment, bone quality, age, and diagnosis have an effect on radiological results. Fifty-eight of the 63 tibial plateaus investigated (92%) showed excellent or good radiological results. In three cases the implant was rated radiologically endangered and in two cases radiologically loose. The results show that successful long-term anchorage depends principally on a primary stable fit. If implantation is inexact, poor bone quality, improper alignment, advanced age, and rheumatoid arthritis may be responsible for unsatisfactory radiological results. The authors conclude that particular importance must be attached to exact primary fixation when several unfavorable factors are encountered.

Aged↗

PubMed1990

Blood gas transport properties in endurance-trained athletes living at different altitudes.

Hemoglobin oxygen binding properties and acid-base status were investigated in Colombian athletes (A) and controls (C) from Cali (C-1000 m) and Bogotá (B-2600 m). [Hb] and Hct values were not influenced by altitude, but Hct was lower in the blood of athletes (in Cali 2.6%, in Bogotá 1.4%). Both training and altitude produced a right-shift of the standard oxygen dissociation curve (P50 in CC 28.5 +/- 0.9 mmHg, AC 31.0 +/- 1.4 mmHg, CB 29.6 +/- 1.5 mmHg) leading to highest P50 in blood of altitude athletes (32.3 +/- 1.1 mmHg). Opposite to the position of the ODC the slope "n" was only increased by altitude influence (delta "n" in controls 0.07, in athletes 0.28). The BCCO2 was increased in AC over the whole saturation range, whereas BCLac was neither significantly influenced by training nor by altitude. All altitude effects can be explained by higher [DPG] (delta[DPG] in controls 5.0 mumol/gHb, in athletes 3.9 mumol/gHb), but the cause for the training effects still remains unclear. The acid base status in altitude residents was characterized by low BE and pCO2, which was most pronounced in altitude athletes, the latter correcting the actual venous pH to normal values. No significant variations of the Hb-O2-binding properties could be detected in athletes one day after leaving high altitude when compared with blood samples of athletes taken at high altitude, whereas BE and venous pCO2 were already increased. It is concluded that high altitude athletes are favoured during aerobic and handicapped during anaerobic exercise after the rapid descent to low altitude.

Acid-Base Equilibrium↗

PubMed1990

[The extent of radical axillary lymph node excision].

A study on histological findings in 1047 patients who underwent total axillary lymph node dissection (topographical levels I-III), was conducted. A mean of 20.3 lymph nodes (LN) was assessed; LN metastases were detected in 492 cases. Retrospective analysis showed that, by mere dissection of LNs level I, 10 of the 492 nodal positive cases (2.0%) would have been classified false negative. Additionally, according to the number of positive LNs detected in stage I, 85 of the 492 patients (17%) would have been assigned to a group with a better prognosis (prognostic groups 1-3, 4-9, greater than or equal to 10 pos. LNs). By mere dissection of LNs levels I and II, only 1 of 492 (0.2%) patients would have been categorized false negative and only 24 patients (5%) would have been included in a group with a better prognosis, on the basis of the number of positive LNs dissected. Thus dissection of LNs stages I and II provides sufficient prognostic information. Since, however, in 145 nodal positive cases (14% of the entire collective e.g. 29.5% of all patients with positive lymph nodes), metastases were detected in level III, these LNs should be removed as well, in order to prevent axillary recurrences. One could only dispense with dissection of level III, if LN metastases levels I and II could be excluded during the operation.

Axilla↗