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Biomedical subjects

W Horstmann

Publications and source records attributed to W Horstmann.

16 recordsLinked to original sources
PubMed2000

Synaptic interactions increase optic flow specificity.

Representations of optic flow are encoded in fly tangential neurons by pooling the signals of many retinotopically organized local motion-sensitive inputs as well as of other tangential cells originating in the ipsi- and contralateral half of the brain. In the so called HSE cell, a neuron involved in optomotor course control, two contralateral input elements, the H1 and H2 cells, mediate distinct EPSPs. These EPSPs frequently elicit spike-like depolarizations in the HSE cell. The synaptic transmission between the H2 and the HSE cell is analysed in detail and shown to be very reliable with respect to the amplitude and time-course of the postsynaptic potential. As a consequence of its synaptic input, the HSE cell responds best to wide-field motion, such as that generated on the eyes when the animal turns about its vertical body axis. It is shown that the specificity of the HSE cell for this type of optic flow is much enhanced if rapid membrane depolarizations, such as large-amplitude EPSPs or spike-like depolarizations, are taken into account rather than the average membrane potential.

Action Potentials↗
PubMed1999

Temperature-dependence of neuronal performance in the motion pathway of the blowfly calliphora erythrocephala

Raising the head temperature within a behaviourally relevant range has strong effects on the performance of an identified neuron, the H1 neuron, in the visual motion pathway of blowflies. The effect is seen as an increase in the mean amplitude of the responses to motion under both transient and steady-state conditions, a considerable decrease in the response latency and an improvement in the reliability of the responses to motion. These temperature-dependent effects are independent of whether the animal is exposed to transient temperature changes or is maintained continuously at the same temperature for its entire life. The changes in the neuronal response properties with temperature may be of immediate functional significance for the animal under its normal operating conditions. In particular, the decrease in latency and the improvement in the reliability with increasing temperature may be relevant for the fly when executing its extremely virtuosic flight manoeuvres.

Journal Article↗
PubMed1991

[Herpes simplex encephalitis in childhood].

This is a report on diagnostic and therapeutic experience in 6 patients aged 3 weeks to 6.3 years suffering from herpes simplex encephalitis. In 2 patients, a 3-week-old newborn and a 1.3-year-old boy, acyclovir-therapy started at days 8 and 17 respectively, following the demonstration of hemorrhagic necrosis in the brain by cranial CT-scan and IgM-specific HSV-antibodies in the blood. A 6.3-year-old girl was treated with acyclovir at day 10 of her illness, when cCT showed hemorrhagic necrosis in the brain. It was not before the 21st day, that diagnosis of HSE could be confirmed serologically. She suffered a relapse of encephalitis 5 weeks later. In a 3-month-old boy, treated with acyclovir at day 4 of his illness, IgM-specific HSV-antibodies were found already at day 4. His clinical course was complicated by subdural effusion. These 4 children survived with severe neurologic sequelae. Another 2 patients, a 5- and 7.5-month-old boy respectively, survived without apparent defect. In both cases vesicles upon the tongue appeared in the beginning of illness. Acyclovir-therapy started at day 7, diagnosis being confirmed serologically later. In our experience HSE should be suspected in children suffering from fever, drowsiness and focal or secondarily generalizing seizures. In these cases antiviral therapy should not depend on serologic findings.

Acyclovir↗
PubMed1984

[Postmortem evaluation of barbiturate poisonings].

The evaluation of barbiturate intoxication as the cause of death is often difficult when the concentration in body fluids and organs is not extremely high. The problem arises because of the great capacity of barbiturates to produce tolerance after chronic use, a property that is often unknown. Therefore, the most abused barbiturates were studied to assess whether chronic intake causes morphological liver changes or not. It was found that the chronic abuse of drugs containing seco-, cyclo-, brallo-, and/or pentobarbital produces hypertrophy of the smooth endoplasmic reticulum of hepatocytes corresponding to that of phenobarbital. Neither acute barbiturate overdose (without a history of abuse) nor chronic abuse of opiates causes similar liver changes. In conclusion, barbiturate tolerance can be evaluated postmortem by light microscopic examination of the liver.

Animals↗
PubMed1981

Two cases of ring chromosome 13. Chromosome banding patterns and mosaic configuration.

Two ring chromosomes 13 were studied by means of various cytogenetic techniques in two psychomotorically retarded male infants. Common features of our patients include microcephalia, hypertelorism, wide and prominent nose bridge, and cryptorchism. Various configurations of the aberrant chromosomes could be identified in cultured skin fibroblasts and peripheral lymphocytes from both patients. Chromosome heteromorphisms and analysis of silver stained nucleolus organizer regions (Ag-NOR) substantiated the parental origin of the ring chromosomes. The more severely affected patient showed a break point at band 13q32 in the long arm of the ring, whereas in the less severely affected the loss of material during ring formation was restricted to the telomere. This provides further evidence for a clinical relevance of the detected mosaic configurations of the rings.

Chromosome Aberrations↗
PubMed1980

Tandem duplication dup(X)(q13q22) in a male proband inherited from the mother showing mosaicism of X-inactivation.

An aberrant X chromosome containing extra material in the long arm was observed in a psychomotoric retarded boy and his healthy, short-statured mother. The proband showed generalized muscular hypotony, growth retardation, and somatic anomalies including hypoplastic genitalia and cryptorchism. Chromosomal banding techniques suggested a tandem duplication of the segment Xq13 leads to Xq22. In the mother the vast majority of lymphocytes showed late replication of the aberrant X chromosome. Some of her cells, however, contained an apparently active aberrant X. Both the early- and late-replicating aberrant X exhibited late replication patterns very similar to those described for normal X chromosomes in lymphocytes. Asynchrony of DNA replication among the two segments Xq13 leads to Xq22 in the dup(X) was never observed. We consider that the clinical picture of the proband is caused by an excess of active X material.

Chromosome Banding↗
PubMed1976

[Results of radiotherapy of bronchial carcinoma (author's transl)].

In a joint retrospective study by 17 radiotherapy clinics in German-speaking countries the results of treatment of bronchial carcinoma after radiotherapy were analysed in 7503 cases. The age peak was between the 60th and 70th year. Squamous-cell carcinoma was the most frequent histological type, followed by anaplastic carcinoma, with adenocarcinoma being rare. There was a high proportion of histologically not clearly identified cases (27% in central and 35% in peripheral carcinomas). Survival rate at one year was 31% for central (3662 patients) and peripheral (961 patients) tumours, but only 2% at five years. Prognostically there was no difference between histological types and kind of radiotherapy or technique, but total dose affected survival rate. At a total dose of less than 5000 rd the survival rate at five years was minimal. The prognosis of combined surgical and radiotherapeutic measures was slightly better than with a radiotherapy alone, but results were unpredictable for the individual case. It is concluded that radiotherapy aiming at cure should be used in imoperable bronchial carcinoma if the tumour state and general condition of the patient appear to make a cure possible. But if this is not the case, radiotherapy should be used only palliatively, i.e. only to ameliorate symptoms.

Adenocarcinoma↗
PubMedDate not supplied

[Tumor markers and endocrinologic aspects in intracranial germinoma].

This report outlines the endocrine abnormalities associated with intracranial germinoma in childhood. The presence of special tumoral markers as alpha 1-fetoprotein and beta-HCG could be of diagnostic value and is important in respect to therapy control. However the reported case shows that despite known radiosensitivity and appropriate radiotherapy localized tumor relapse may arise soon after treatment.

Adolescent↗