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Biomedical subjects

S Evers

Publications and source records attributed to S Evers.

At least 109 records · Page 6Linked to original sources
PubMed1998

Progressive peripheral and central sensory tract lesion in HIV-infected patients evidenced by evoked potentials (a three-year follow-up study).

OBJECTIVE: To investigate progression of peripheral and central sensory tract lesion and its correlation to immunological deterioration. METHODS: Clinical and neurophysiological investigation (evoked potentials of the median and tibial nerve) and immunological parameters (CD4-cells, beta 2-microglobuline) were followed up in 160 patients (24 females, 136 males, HIV infection for 2.7 +/- 2.3 years, mv +/- 1 sd) up to four times over approximately 3 years regardless of disease stage and evidence of neurological symptoms. Recordings were done using needle electrodes over the Th12 and C7 spinous process and from the scalp (10/20 system) in the conventional manner. Statistical analysis was performed intraindividually and in comparison to normal laboratory values (n = 96). RESULTS: All parameters deteriorated during the follow-up period. Statistical analysis showed significant differences between probands and patients for evoked potentials, but also a significant deterioration for evoked potentials after three years at the end of the follow-up study. A significant correlation between progressive impairment of evoked potentials and laboratory data was found. CONCLUSION: HIV infection induces a progressive lesion of the ascending sensory tracts. The results indicate a peripheral neuropathy as well as a progressive lesion of the ascending central sensory tracts. Pathogenesis of polyneuropathy and of central sensory tract lesion is up to now conjectural. Laboratory investigations indicate a clear-cut correlation between immunological alterations induced by HIV infection and its neurologic manifestation on ascending sensory tracts.

Adult↗
PubMed1998

Impact of antiretroviral treatment on AIDS dementia: a longitudinal prospective event-related potential study.

We investigated the impact of antiretroviral treatment on event-related potentials (ERP) as a possible marker of AIDS dementia. A total of 154 HIV-infected patients without central nervous system (CNS) neoplasm or opportunistic infection were examined and randomized to receive either zidovudine 500 mg/day or no antiretroviral treatment. The participants were prospectively examined by visually evoked ERP in a longitudinal design. Latencies and amplitudes of ERP were evaluated at the beginning of the study, after 1 year, and after 2 years. After 1 year, 98 patients could be analyzed, 47 of whom were taking zidovudine. In the treatment group, P3 latency was 419 +/- 55 msec at baseline and 424 +/- 52 msec at follow-up (not significant). In the patients without treatment, P3 latency was 437 +/- 42 msec at baseline and 462 +/- 53 msec at follow-up (p < .0001, Wilcoxon test). A significant inverse correlation existed between P3 latency and CD4 cell count in both groups. The increase of P3 latency in untreated patients and a stable P3 latency in treated patients could be confirmed in a subgroup analysis of 21 patients with a follow-up of three examinations in a 2-year period. Our data suggest that zidovudine has a positive impact on AIDS dementia as measured by ERP. This finding was observed in patients in different stages of HIV infection, thus suggesting that zidovudine is indicated in all stages of HIV infection to treat encephalopathy.

AIDS Dementia Complex↗
PubMed1998

Reference map of the low molecular mass proteins of Haemophilus influenzae.

Analysis of the proteome of Haemophilus influenzae by two-dimensional polyacrylamide gel electrophoresis on conventional Tris-glycine gels does not usually result in efficient separation of the proteins in the 5-20 kDa range, which are mainly accumulated in the lower acidic and basic regions. In order to improve the separation of the low molecular mass proteins, we used homogeneous Tricine gels of two urea concentrations in the second-dimensional separation. The Tricine gel systems allowed the efficient and reproducible separation of the proteins of the microorganism with masses between 5 and 20 kDa, however, no proteins with masses below 5 kDa could be visualized. Approximately 80 proteins migrating in the 5-25 kDa region were identified by matrix assisted laser desorption/ionization - mass spectrometry, of which 40 identified for the first time. The digestion of the low mass proteins often produced only few peptides, which were insufficient for confident identification by mass spectrometry. Therefore, the identification was occasionally achieved by a sequential digestion with two proteases, trypsin or endoproteinase Lys-C as first and carboxypeptidase P as second enzyme. The gel system described may be useful for the efficient separation of low molecular mass proteins from other organisms to construct standard maps.

Bacterial Proteins↗
PubMed1998

Strategies towards a better understanding of antibiotic action: folate pathway inhibition in Haemophilus influenzae as an example.

Two-dimensional electrophoresis was applied to the global analysis of the cellular response of Haemophilus influenzae to sulfamethoxazole and trimethoprim, both inhibitors of tetrahydrofolate synthesis. Deregulation of the synthesis rate of 118 proteins, involved in different metabolic pathways, was observed. The regulation of the genes involved in the metabolism of the amino acids methionine, threonine, serine, glycine, and aspartate was investigated in detail by analysis of protein synthesis and Northern hybridization. The results suggested that the synthesis of methionine biosynthetic enzymes in H. influenzae is regulated in a similar fashion as in Escherichia coli. A good correlation between the results obtained by Northern hybridization and quantification of protein synthesis was observed. In contrast to trimethoprim, sulfamethoxazole triggered the increased synthesis of the heat shock proteins DnaK, GroEL, and GroES.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1998

[Routine electroencephalogram in follow-up of patients with HIV infections of different stages. A long-term study].

Electroencephalography (EEG) is a well-tolerated non-invasive method and is therefore well suited for repetitive examinations. We performed serial EEG's on 117 HIV patients without any clinical signs of secondary neuromanifestation in order to document electroencephalographic changes in the course of HIV infection. Clinical signs of HIV-associated encephalopathy presented 18 patients at the first examination and 23 at reexamination. EEGs were analyzed visually; there was a mean interval of 20.3 +/- 13.7 months between the first and the second examination. Significant slowing of background activity occurred in the course of the disease; the alpha rhythm decreased from 10.7 +/- 2.3 Hz to 10.0 +/- 2.4 Hz (P < 0.05) with an increase in amplitudes from 60.9 +/- 24.6 microV to 69.5 +/- 33.7 microV (p < 0.05). The percentage of spontaneous dysrhythmias also increased from 30.7% to 41.8% (P < 0.05); pathological findings provoked by hyperventilation increased from 13.6% to 18.2%. Foci occurred rarely and did not increase in frequency with time. CD4 cell counts decreased from 294.2 +/- 209.5/microliter to 188.7 +/- 208.3/microliter (P < 0.01). The results of this study indicate progressive CNS dysfunction with worsening of the immunostatus.

AIDS Dementia Complex↗
PubMed1998

The influence of acetylsalicylic acid on cognitive processing: an event-related potentials study.

The central effects of acetylsalicylic acid (ASA) are discussed controversially. In animal models, it has been shown that ASA can interact with the central serotonergic and catecholaminergic neuronal system. However, the relevance of this interaction for humans is still unknown. We performed a study on the influence of ASA on central cognitive processing. In 25 healthy subjects (age 21-56 years), visually evoked event-related potentials (ERP) and reaction time under IV ASA medication were recorded. ERP were evoked by an oddball paradigm. As compared to placebo, ASA decreased the latency of the P3 component significantly in a time interval of 20-40 min after administration. The latency of the N2 component was significantly decreased about 25 min after administration; the latency of the exogenous P2 component was not influenced by ASA. The mean choice reaction time was significantly decreased by ASA 35 min after administration. At this time point, there was a significant correlation between decrease in reaction time and increase in ASA plasma level. The data show that IV administration of ASA has an accelerating effect on the endogenous components of visual ERP and on reaction time. This finding suggests that ASA can influence central cognitive processing, possibly by ASA induced changes of neurotransmitters. Since serotonin can be released by ASA and serotonin release leads to a decrease of ERP latencies. we assume that ASA most likely influences cognitive processing via the central serotonergic transmitter system.

Adult↗
PubMed1998

Prevalence of factor V Leiden mutation in young adults with cerebral ischaemia: a case-control study on 225 patients.

Cerebral ischaemia in young adults is a well-recognised disease, and approximately half of the cases remain aetiologically unclear despite extensive investigations. Thrombophilias are known to cause a subset of ischaemic strokes in this population. The factor V Leiden (FVL) mutation, causing resistance to activated protein C, has recently been recognised as the most important genetic thrombophilia in the Western population. Carriers of this gene mutation have a sevenfold increased risk of phlebothrombosis. We undertook this study to evaluate whether the FVL mutation constitutes a risk factor for juvenile cerebral ischaemias. A total of 225 patients aged < or = 45 years at onset of cerebral ischaemia and 200 age-matched healthy controls were investigated. The overall frequency of heterozygosity for the FVL mutation did not differ significantly between patients (8.4%) and controls [6.0%; odds ratio (OR) 1.4, 95% confidence interval (CI) 0.7-3.1]. In the subgroup of patients with cryptogenic cerebral ischaemia (n = 94), however, a significantly higher frequency of this gene defect (15.9%) was found compared with the controls (OR 3.0, CI 1.3-6.6). Further trends towards higher frequencies of the FVL mutation were found in patients with patent foramen ovale (OR 1.9), individual (OR 2.1) or family history of previous thrombembolisms (OR 2.0), and in those aged 25 years at onset of disease (OR 1.9, all not significant). In conclusion, the FVL mutation is not a risk factor for cerebral ischaemia of the young. However, our results suggest that this gene mutation plays an aetiological role in the subgroup of patients suffering from 'cryptogenic' ischaemic events.

Adolescent↗
PubMed1998

Peripheral autonomic potentials in primary headache and drug-induced headache.

Autonomic functions of different primary headache types have been investigated in several studies, most of them analyzing cardiovascular reflex mechanisms or biochemical changes. The results are contradictory; only in tension-type headache and in cluster headache has a sympathetic hypofunction been shown in a preponderance of studies. We analyzed the peripheral autonomous potentials (PAPs) in different primary headache types and in drug-induced headache and compared the results with those of healthy subjects and of patients with low back pain. Latencies of PAPs were significantly increased in all headache types but not in low back pain; amplitudes of PAPs did not show significant differences compared to healthy subjects. Patients with a long duration of drug abuse had increased PAP latencies, whereas patients with a high number of migraine attacks per year had decreased latencies. Our data suggest that sympathetic hypofunction as measured by PAP latencies is a general phenomenon in headache but not in all pain syndromes. Drug abuse leads to an increase of this hypofunction. While measuring PAPs is not an appropriate method by which to differentiate between headache disorders, it allows assessment of autonomic disturbances in primary and drug-induced headache.

Adult↗
PubMed1998

Influence of end-stage renal failure and hemodialysis on event-related potentials.

Chronic renal failure frequently causes uremic encephalopathy with impairment of different cognitive functions, but the pathophysiology of uremic encephalopathy is still unknown. We measured visually evoked event-related potentials (ERPs) in 33 neurologically asymptomatic patients before and after they underwent hemodialysis and compared their data with those of a strictly age-matched healthy control group. Before hemodialysis, the patients' P3 latency was significantly increased and P3 amplitude was significantly decreased as compared with that of the healthy control group. After hemodialysis, P3 latency of the patients showed a significant decrease (457+/-56 before and 438+/-54 ms after hemodialysis) and the P3 latency habituation during the ERP measurement was also significantly decreased. Patients with higher levels of blood urea nitrogen (BUN), creatinine, and uric acid performed better in ERP measurement than did patients with lower levels. Hemoglobin did not influence ERP latencies and amplitudes. Our data suggest that impaired cognitive processing can be disclosed by ERP even in neurologically asymptomatic chronic renal disease. Removal of uremic toxins by hemodialysis leads to an improvement in cognitive processing.

Adult↗
PubMed1998

Shifts of intracellular pH distribution as a part of the signal mechanism leading to the elicitation of benzophenanthridine alkaloids . Phytoalexin biosynthesis in cultured cells of eschscholtzia californica

Cultured cells of Eschscholtzia californica (Californian poppy) respond to a yeast elicitor preparation or Penicillium cyclopium spores with the production of benzophenanthridine alkaloids, which are potent phytoalexins. Confocal pH mapping with the probe carboxy-seminaphthorhodafluor-1-acetoxymethylester revealed characteristic shifts of the pH distribution in challenged cells: within a few minutes after elicitor contact a transient acidification of cytoplasmic and nuclear areas occurred in parallel with an increase of the vacuolar pH. The change of proton concentration in the vacuole and in the extravacuolar area showed a nearly constant relation, indicating an efflux of vacuolar protons into the cytosol. A 10-min treatment with 2 mM butyric or pivalic acid caused a transient acidification of the cytoplasm comparable to that observed after elicitor contact and also induced alkaloid biosynthesis. Experimental depletion of the vacuolar proton pool reversibly prevented both the elicitor-triggered pH shifts and the induction of alkaloid biosynthesis. pH shifts and induction of alkaloid biosynthesis showed a similar dependence on the elicitor concentration. Net efflux of K+, alkalinization of the outer medium, and browning of the cells were evoked only at higher elicitor concentrations. We suggest that transient acidification of the cytoplasm via efflux of vacuolar protons is both a necessary and sufficient step in the signal path toward biosynthesis of benzophenanthridine alkaloids in Californian poppy cells.

Journal Article↗
PubMed1998

Secondary hyperkalaemic paralysis.

Besides the hereditary hyperkalaemic paralysis, a secondary form exists which often mimicks Guillain-Barre syndrome. A 62 year old patient is reported on who developed severe hyperkalaemic paralysis on the basis of mild renal failure and additive spironolactone intake. Neurophysiological examinations disclosed normal muscle fibre activity but delayed nerve conduction velocities indicating that the mechanism underlying secondary hyperkalaemic paralysis is different from channelopathies. Haemodialysis led to complete recovery. Review of the medical literature showed that spironolactone intake is the most common cause of secondary hyperkalaemic paralysis. Typical symptoms are flaccid tetraplegia sparing the cranial nerves with only mild or lacking sensory impairment. Symptoms promptly resolve after haemodialysis or after glucose and insulin infusion. Only three out of 18 patients reviewed died, because of cardiopulmonary complications. Thus the prognosis of secondary hyperkalaemic paralysis is good.

Diagnosis, Differential↗
PubMed1998

Event-related potentials (P300) in primary headache in childhood and adolescence.

There is strong evidence for a loss of habituation during cognitive processing in migraine as measured by P300 and contingent negative variation in adults. Event-related potentials evoked by an oddball paradigm have not yet been studied in children and adolescents suffering from different primary headache types. We recorded visually evoked event-related potentials (two consecutive trials, 200 stimuli each) in 48 children and adolescents suffering from migraine without or with aura, from episodic tension-type headache, and from ergotamine-induced headache and analyzed the latencies, amplitudes, and reaction times. No statistically significant differences were noted between all headache types and healthy controls analyzing the averaged parameters for the whole measurement. However, a highly significant loss of cortical habituation as measured by P300 amplitude and latency could be observed in migraine without and with aura by analyzing the first and the second trial of measurement separately. This phenomenon increased with age and could not be seen in healthy controls, or patients with tension-type headache or ergotamine-induced headache. Our data suggest a specific cognitive processing in migraine even in children and adolescents. Measurement of the habituation effect in P300 latency and amplitude provides a specific method to differentiate between primary headache types in childhood and adolescence.

Adolescent↗
PubMed1998

Transient ischemic attacks caused by trumpet playing.

We report a young musician who experienced transient ischemic attacks during trumpet playing. Cardiovascular examination revealed a patent foramen ovale; Doppler ultrasound of the middle cerebral arteries detected microembolic signals with increased rates during trumpet playing and Valsalva maneuver. After operative occlusion of the foramen ovale, the symptoms disappeared and no microembolic signals could be detected.

Adolescent↗
PubMed1998

Prostaglandin analog mechanisms are not effective in refractory chronic cluster headache.

Prostaglandin E analogs have been shown to be effective in the treatment of refractory trigeminal neuralgia in patients with multiple sclerosis. Prostaglandin E inhibits the functions of T lymphocytes which are involved in the pathophysiology of cluster headache. Therefore, a double-blind, placebo-controlled, crossover study on the efficacy of misoprostol in chronic refractory cluster headache was performed. Eight patients were treated with 600 micrograms misoprostol and with placebo for a 2-week period. No differences in attack frequency, intensity, global impression, and side effects could be detected, suggesting that prostaglandin E analogs are not effective in the treatment of chronic cluster headache.

Adult↗
PubMed1998

[Status of music therapy in inpatient pediatrics and child and adolescent psychiatry].

In order to study the present situation of music therapy in hospitals of pediatrics and of child and adolescent psychiatry in the FRG, a postal survey at these hospitals was performed. The personnel situation, methods of music therapy and indications for music therapy were examined. The data are analysed according to the kind and the size of hospital; they are compared to results obtained in a survey at out-patient pediatrics and to a similar survey from the year 1990.

Adolescent↗