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Biomedical subjects

R Schmidt

Publications and source records attributed to R Schmidt.

At least 613 records · Page 34Linked to original sources
PubMed1986

Effects of pre- and postnatal administration of antibodies to nerve growth factor on the morphological and biochemical development of the rat adrenal medulla: a reinvestigation.

Whether or not adrenal medullary (chromaffin) cells which respond to nerve growth factor (NGF) both in vitro and in vivo require NGF for their normal development is controversial. Systemic deprivation of endogenous NGF by injection of anti-NGF antibodies into rat fetuses or by transfer of anti-NGF to the offspring of autoimmunized mothers has provided conflicting results. We have reinvestigated the effects of a specific antiserum to NGF on the morphology, catecholamine (CA) and neuropeptide (Met-enkephalin, Met-ENK; substance P, SP) content, and choline acetyltransferase (ChAT) activity of the rat adrenal medulla. Fetuses were injected with anti-NGF antibodies on day 17 of gestation and postnatally at daily intervals for 7 days. The histological appearance of adrenal medullae of anti-NGF injected animals was not altered as compared to controls. Ultrastructurally, no degenerative changes or developmental retardation of chromaffin cells could be detected. However, numbers of chromaffin granules per micron 2 of cytoplasmic area were greater and the mean diameters of the cores of adrenaline storage granules were smaller in antibody-treated than in control animals. CA and SP content, ratios of adrenaline to noradrenaline and ChAT activities were identical in anti-NGF-treated and control animals. Anti-NGF antibodies caused a reduction of adrenal Met-ENK by 40% as compared to controls. Superior cervical ganglia from the same animals were used to document immunosympathectomy induced by the antiserum. They displayed the well-established structural alterations and a marked reduction of the CA content. We conclude that administration of anti-NGF antibodies to embryonic and early postnatal rats induces only subtle changes in the ultramorphology of chromaffin cells without altering the development of normal CA levels. The small, yet significant effects of anti-NGF antibodies on adrenal Met-ENK, however, may suggest a role for endogenous NGF in the regulation of opioid peptide metabolism in developing chromaffin cells.

Adrenal Medulla↗
PubMed1986

Modern physical methods for analysing elements and structures in histochemistry.

Chemical analysis supported to a greater and greater degree by physical principles and measurement techniques offers some advantages for application in biomedical research and is able to complete histochemical procedures in elemental analysis. The described methods, such as electron-probe X-ray microanalysis, Auger electron spectrometry, cathodoluminescence analysis, electron diffraction, secondary ion mass spectrometry, electron spectrometry for chemical analysis, laser microprobes based on emission spectrometry, mass spectrometry and luminescence spectrometry yield qualitative and quantitative information about the inorganic (and organic) constituents and their distributions of subcellular microvolumes of biological tissues. Information content, figure of merit, applications, and limitations of these methods, and the special preparation techniques of biological materials are discussed.

Electron Probe Microanalysis↗
PubMed1986

Intraoperative autotransfusion with a new disposable system.

In the past 2 years we have used a simple, disposable set for intraoperative autotransfusion. The system consists of a rigid plastic case with a flexible bag inside constituting a 600 ml reservoir which can be connected to any suitable vacuum source. We used it so far in 56 patients undergoing various vascular operations who were autotransfused a total of about 160 units of blood without any complications with regard to blood coagulation or hemolysis.

Blood Transfusion, Autologous↗
PubMed1986

[Pathological insertion of the placenta after the 20th week of pregnancy--its importance in the course of pregnancy and delivery].

The present paper reports on the results of sonographic diagnosis of a pathologic insertion of the placenta after the 20th week of pregnancy and its importance with regard to the course of pregnancy and birth. The conversion of a primarily pathologic placental insertion to a "normal" insertion at term depends on the severity of the placental insertion disorder and the date of diagnosis. The frequency of pathologic insertions after the 20th week of pregnancy amounted to 4.2% of the patients examined. The rate of conversion from pathologic to normal placental insertion was 91%, if marginal/partial and total placenta previa are accepted as definitive diagnoses at term. The insertion remained unchanged up to term in approximately 90% of the cases in which total placenta previa was sonographically diagnosed. The sonographic diagnosis of "pathologic insertion of the placenta" after the 20th week of pregnancy is associated with severe complications in the subsequent course of pregnancy and birth. There is a significant cluster of vaginal hemorrhage in the last trimester of pregnancy; cesarean deliveries are common; there are more cases of transfer to pediatric clinics, and the incidence of retarded fetal growth and perinatal mortality is higher. The present authors believe that where the diagnosis of placenta previa has been confirmed sonographically, prophylactic measures and, in the last resort, a planned cesarean delivery can contribute to a reduction in maternal morbidity and also to a decrease in perinatal morbidity and mortality.

Abortion, Spontaneous↗
PubMed1986

[Diagnosis of holoprosencephaly with cyclopia in the fetus].

The typical ultrasound findings in cases of fetal holoprosencephaly with hypotelorism and cyclopia are explained with reference to a case history. Hypotelorism was confirmed by measurement of the distance between the orbits of the fetus.

Abnormalities, Multiple↗
PubMed1986

Gamma loop contributing to maximal voluntary contractions in man.

A local anaesthetic drug was injected around the peroneal nerve in healthy subjects in order to investigate whether the resulting loss in foot dorsiflexion power in part depended on a gamma-fibre block preventing 'internal' activation of spindle end-organs and thereby depriving the alpha-motoneurones of an excitatory spindle inflow during contraction. The motor outcome of maximal dorsiflexion efforts was assessed by measuring firing rates of individual motor units in the anterior tibial (t.a.) muscle, mean voltage e.m.g. from the pretibial muscles, dorsiflexion force and range of voluntary foot dorsiflexion movements. The tests were performed with and without peripheral conditioning stimuli, such as agonist or antagonist muscle vibration or imposed stretch of the contracting muscles. As compared to control values of t.a. motor unit firing rates in maximal isometric voluntary contractions, the firing rates were lower and more irregular during maximal dorsiflexion efforts performed during subtotal peroneal nerve blocks. During the development of paresis a gradual reduction of motor unit firing rates was observed before the units ceased responding to the voluntary commands. This change in motor unit behaviour was accompanied by a reduction of the mean voltage e.m.g. activity in the pretibial muscles. At a given stage of anaesthesia the e.m.g. responses to maximal voluntary efforts were more affected than the responses evoked by electric nerve stimuli delivered proximal to the block, indicating that impaired impulse transmission in alpha motor fibres was not the sole cause of the paresis. The inability to generate high and regular motor unit firing rates during peroneal nerve blocks was accentuated by vibration applied over the antagonistic calf muscles. By contrast, in eight out of ten experiments agonist stretch or vibration caused an enhancement of motor unit firing during the maximal force tasks. The reverse effects of agonist and antagonist vibration on the ability to activate the paretic muscles were evidenced also by alterations induced in mean voltage e.m.g. activity, dorsiflexion force and range of dorsiflexion movements. The autogenetic excitatory and the reciprocal inhibitory effects of muscle vibration rose in strength as the vibration frequency was raised from 90 to 165 Hz. Reflex effects on maximal voluntary contraction strength similar to those observed during partial nerve blocks were not seen under normal conditions when the nerve supply was intact.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1986

Prospective randomized trial concerning hyper- and normoprolactinemia and the use of bromoergocryptine in patients with metastatic breast cancer.

This prospective trial was designed to help in selecting therapy for patients with elevated and normal plasma prolactin. Ninety-two patients entered this trial, of whom 86 were evaluable for final analysis. Hyperprolactinemic patients (n = 31) were randomized to receive VAC/FMC chemotherapy with or without bromoergocryptine. Normoprolactinemic patients with 'low risk' metastatic disease (disease-free interval greater than 30 months, ER/PR positive or unknown) were treated with medroxyprogesterone acetate or VAC/FMC chemotherapy. Normoprolactinemic 'high risk' patients (n = 42) (disease-free interval less than 30 months, EP/PR negative) received VAC/FMC chemotherapy with or without medroxyprogesterone acetate (MAP). The results show that bromoergocryptine does not improve response rate, duration of response and survival. Median survival of patients with elevated basal plasma prolactin (greater than 15 ng/ml) is reduced to 9 months compared to patients with normal basal plasma prolactin (17 months, log-rank p = 0.005). Unexpectedly, TRH stimulation proved inappropriate to separate normo- and hyperprolactinemic patients in terms of survival. Normoprolactinemic 'low risks' (tamoxifen failures) were observed to qualify for further hormone therapy (median survival 21+ months). Normoprolactinemic 'high risks' showed median survival of about 12 months with no apparent benefit for those receiving MAP, additionally. The results suggest that basal hyperprolactinemia, disease free interval, ER/PR receptor status, and liver metastasis are important prognostic variables. Endocrine and cytotoxic chemotherapy should be selected according to these risk factors.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

[Atomic absorption spectrophotometric determination of zinc in granulocytes, lymphocytes and serum of untreated and alloxan diabetic rats].

Atomic absorptions spectrophotometric determinations of zinc in serum, granulocytes and lymphocytes after separation of blood samples of normal and alloxan diabetic rats, control persons and diabetics by the method of Böyum verify our conception that changes of metal content and structure in cells by metal chelating agents are induced primary by chemical and secondary by disturbed carbohydrate metabolism conditions. Alloxan (200 mg/kg of body weight, intraperitoneally) destroys selectively not only the B-cells of the islets of Langerhans but also the granulocytes, while the lymphocytes are not changed in respect to the zinc content and cell count. The lymphocytes of diabetics are unchanged in the zinc content, too. The earlier opinion that leucocytes belong to the slowly exchanging zinc compartments of the blood is only exact for lymphocytes, whereas the granulocytes and the serum, corresponding to an exchange pool of metal ions, may play a more important role in the transport system of the zinc.

Animals↗
PubMed1986

Effect of hypometabolism on cell injury.

Rats were given galactosamine 1 g/kg i.p. Pretreatment with propylthiouracil 14 days prior to intoxication and surgical thyroidectomy 10 days prior to intoxication significantly reduced the elevation of SGOT and GLDH activities and protected against hepatocellular necrosis 28 h after intoxication. T3 and T4 levels decreased significantly within the first 2 days in patients with acute myocardial infarction, while rT3 levels were found to be elevated within this period. TRH and TSH decreased during the first 2 days of the observation period and increased in course of time. The protective role of the "hypometabolic" state is discussed.

Animals↗
PubMed1986

[The quality of washed autotransfused erythrocytes. The elimination of plasma hemoglobin, osmotic fragility and survival rate of retransfused erythrocytes].

Intraoperative transfusion has until recently been understood to mean full retransfusion of the blood removed by a suction pump without significant changes due to external influences, which considerably limited its utilization. Intraoperative transfusion can only be performed without decisive disadvantages when the blood can be suctionally removed in large amounts and immediately retransfused. In recent years, the Cell Saver has provided a system which can also prepare soiled blood for retransfusion. Extensive orthopedic surgery entails large blood losses due to oozing from expanded wound areas; only rarely does acute bleeding occur. Because of intensive tissue contact, the suctioned blood has been soiled with activated clotting factors, lytic enzymes, free haemoglobin from damaged red cells, cleaning solutions, and other undesired elements. With the Cell Saver system, it is possible to remove the plasma and recover 70-80% of the intact red cells sufficiently freed from stroma and free haemoglobin. The osmotic fragility of these cells served as a measure of integrity and membrane stability. They were compared to red cells withdrawn preoperatively and showed an identical osmotic relationship. Determining the survival rate of the retransfused cells in vivo shows that they provide a high-quality and in most cases, a sufficient replacement of blood loss. Even after 6 days, over 70% were found in the circulating blood. Premature, disproportionate elimination, which could be dangerous for the patient, does not occur.

Blood Preservation↗
PubMed1985

[Erythema migrans borreliosis in the Federal Republic of Germany. Epidemiology and clinical aspects].

A positive antibody titre against Ixodes-ricinus-Borrelia (burgdorferi), using indirect immunofluorescence or ELISA, could be detected in serum and (or) liquor of 935 (32%) out of a total of 2955 patients between January 1984 and July 1985. In 289 of these cases the typical clinical manifestations were lacking whereas a characteristic disease picture enabled a diagnosis to be made in 171 patients with negative or borderline antibody titres. The 1106 cases of infection observed covered all regions of the country. A typical clinical syndrome was seen in 817 (74%) of these. Most common were erythema chronicum migrans (n = 458) and meningopolyneuritis Garin-Bujadoux-Bannwarth (n = 404); in 42% of the cases meningopolyneuritis was preceded by an erythema. Arthritis (n = 63), acrodermatitis chronica atrophicans (n = 72), carditis (n = 13) and lymphadenosis benigna cutis (n = 5) were much less common. Chronic Borrelian encephalomyelitis (n = 45) appeared surprisingly often (n = 45). The fact that in 73% of cases the various syndromes appeared alone, were double in 24% and combined only in 3%, illustrates the polymorphic nature of this disease.

Adolescent↗
PubMed1985

Plasma membrane transglutaminase and cornified envelope competence in cultured human keratinocytes.

When confluent cultures of the transformed human keratinocyte line SV-K14 are shifted to serum-free medium the cells achieve, within 4 days, the ability to synthesize a cornified envelope after challenge with the Ca2+ ionophore A23187. During these 4 days the enzyme transglutaminase (EC 2.3.2.13), which catalyses the cross-linking of different envelope precursor proteins, is partially transferred from the cytosolic pool into the plasma membrane. The association of the enzyme with the plasma membrane proves to be an essential step in the envelope formation since a direct correlation between plasma membrane-bound transglutaminase and envelope competence is observed. Retinoids block the insertion of the enzyme and therefore prevent envelope formation.

Acyltransferases↗
PubMed1985

[Infrared erythema].

This article deals with the immediate effect of infra-red (IR) irradiation on human skin. The cutaneous response to IR significantly differed from that to polychromatic UV rays. The IR erythema showed a reticular pattern and was monophasic. Minimal erythema (ME) appeared without latency and faded a few minutes later. Induction of IR-ME required a radiation doses about 15,000 times higher (187-295 J/m2) than was needed for UVB erythema. The maximum erythema also occurred immediately after exposure to IR and faded away within one to four hours. The response was biphasic in only one of 28 test persons. Histological studies revealed dilated vessels and perivascular accumulation of degranulated mast cells.

Adult↗