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Biomedical subjects

D Ebert

Publications and source records attributed to D Ebert.

At least 55 records · Page 3Linked to original sources
PubMed1998

Experimental evolution of parasites.

Serial passage experiments are a form of experimental evolution that is frequently used in applied sciences; for example, in vaccine development. During these experiments, molecular and phenotypic evolution can be monitored in real time, providing insights into the causes and consequences of parasite evolution. Within-host competition generally drives an increase in a parasite's virulence in a new host, whereas the parasite becomes avirulent to its former host, indicating a trade-off between parasite fitnesses on different hosts. Understanding why parasite virulence seldom escalates similarly in natural populations could help us to manage virulence and deal with emerging diseases.

Adaptation, Physiological↗
PubMed1998

[Atypical neuroleptics--the future of schizophrenia treatment?].

Since schizophrenia is not a rare occurrence and is often chronic, the general practitioner and internist providing primary care should also be informed on new developments in treatment with neuroleptics. A major new form of treatment is provided by the so-called atypical neuroleptics which, however, in terms of their receptor specificity are not a uniform group, and have only a few properties in common. A prototype of this group is clozapine (Leponex), which has a good antipsychotic effect and virtually no action on the extrapyramidal motor system (EPS). Whether clozapine is also capable of improving the primary negative symptoms of schizophrenia (e.g. flattering of affect, reduction of drive, cognitive disorders, etc.) has not yet been ascertained. On account of the rare but possibly fatal agranulocytosis it may induce, it may be prescribed only when certain safety precautions are taken. Risperidone (Risperdal) has similar efficacy against the classical positive symptoms, with no action on the EPS (up to a medium dosage), and has no hematological effects. Other atypical neuroleptics have recently become available: quetiapine, olanzapine and sertindole. They have at least some of the advantages of clozapine but a very low risk of producing hematological effects. However, before they are widely used in the doctor's practice, further clinical experience is needed.

Antipsychotic Agents↗
PubMed1998

[Sleep deprivation and subsequent sleep phase advance stabilizes the positive effect of sleep deprivation in depressive episodes].

Approximately 60% of patients with major depression disorder show a beneficial response to total sleep deprivation (TSD), but the positive effect of TSD is short, and naps or the following night's sleep destroy it. Various methods have been tried to stabilize the positive sleep-deprivation effect. A consecutive 1-week advance in the sleep phase stabilized mood in more than 50% of the sleep-deprivation responders. We examined 40 male patients with major depression who in addition to medical treatment took part in a phase advance study to prove possible synergistic effects. About 60% of the patients showed positive mood stabilization after 1-week of treatment when the patients were sleep-deprivation responders. These results support data from other groups.

Adult↗
PubMed1998

Neurobiological similarities in antidepressant sleep deprivation and psychostimulant use: a psychostimulant theory of antidepressant sleep deprivation.

This paper attempts to summarize the evidence for the hypothesis that psychostimulant-like neurotransmitter processes within certain regions of the limbic system induce the positive effects of antidepressant sleep deprivation (SD). Preclinical and human studies indicate similar neurobiological effects of psychostimulants such as amphetamines, cocaine and SD. In clinical use, SD and psychostimulants have similar characteristics and behavioral effects. Furthermore, acute psychostimulant challenge decreases limbic metabolism in imaging studies, and SD decreases elevated limbic metabolism in SD responders, indicating that psychostimulant-like neurotransmitter release could decrease limbic metabolism in SD responders. Most antidepressant pharmacotherapies change the reactivity of the dopamine system, and a decrease of presynaptic dopamine or postsynaptic availability can induce depression. Sleep is accompanied by a reduction of catecholamine release and those processes which are increased by psychostimulants. It is concluded that a proposed regional postsynaptic deficit in catecholaminergic neurotransmission can be overcome either acutely by enhanced release during SD or psychostimulant use, or chronically by changes in receptor sensitivity or gene expression due to antidepressant therapies. A postsynaptic deficit in these areas becomes evident if presynaptic release is reduced in conditions such as sleep. Therefore, sleep is depressiogenic for predisposed individuals and the reduction of sleep avoids understimulation of subsensitive postsynaptic processes, which are enhanced by psychostimulants.

Animals↗
PubMed1998

Sleep and the cholinergic rem sleep induction test in patients with primary alcoholism.

Sleep disturbances of alcoholics while actively drinking and at the beginning of, and during, abstinence were frequently reported. Recently, Gillin et al. (1994) showed that a high "REM sleep pressure" at the time of admission to a 1-month inpatient alcohol treatment program predicted the relapse in nondepressed patients with primary alcoholism at 3 months following hospital discharge. We investigated 24 patients with primary alcoholism after 2-3 weeks abstinence in the sleep laboratory; in 15 of these patients the cholinergic REM sleep induction test (CRIT) with 10 mg galanthamine was performed additionally. In comparison with an age- and sex-matched healthy control group, patients had a heightened "REM sleep pressure" including shortened REM latency and increased REM density. A decrease of serotonergic neurotransmission is proposed as being the neurochemical mechanism to explain the results in alcoholic subjects. Follow-up investigations will clarify whether the sleep abnormalities in alcoholism are state- or trait-markers and whether they are suitable to predict the relapse risk.

Adult↗
PubMed1998

Cystic adventitial degeneration and entrapment syndrome of the popliteal artery as a differential diagnosis of popliteal stenosis or occlusion in the younger age group.

Differential diagnosis in angiographically found popliteal artery stenosis or occlusion comprises some distinct and clinically important entities that should be considered as management and prognosis may vary considerably. We present two patients with the final diagnosis of cystic adventitial disease of the popliteal artery and popliteal artery entrapment syndrome. Angiographic findings and the value of additional diagnostic imaging are discussed.

Adult↗
PubMed1997

Optimal killing for obligate killers: the evolution of life histories and virulence of semelparous parasites.

Many viral, bacterial and protozoan parasites of invertebrates first propagate inside their host without releasing any transmission stages and then kill their host to release all transmission stages at once. Life history and the evolution of virulence of these obligately killing parasites are modelled, assuming that within-host growth is density dependent. We find that the parasite should kill the host when its per capita growth rate falls to the level of the host mortality rate. The parasite should kill its host later when the carrying capacity, K, is higher, but should kill it earlier when the parasite-independent host mortality increases or when the parasite has a higher birth rate. When K(t), for parasite growth, is not constant over the duration of an infection, but increases with time, the parasite should kill the host around the stage when the growth rate of the carrying capacity decelerates strongly. In case that K(t) relates to host body size, this deceleration in growth is around host maturation.

Animals↗
PubMed1997

1H-magnetic resonance spectroscopy in obsessive-compulsive disorder: evidence for neuronal loss in the cingulate gyrus and the right striatum.

We compared 12 patients with obsessive-compulsive disorder (OCD) and six control subjects by 1H-magnetic resonance spectroscopy. Significantly lower relative N-acetyl-aspartate (NAA) levels were found in the right striatum of OCD patients, as well as a decrease of anterior cingulate NAA that correlated with severity of illness. Age and sex were correlated to striatal NAA levels.

Adult↗
PubMed1997

Duration of lithium treatment and brain lithium concentration in patients with unipolar and schizoaffective disorder--a study with magnetic resonance spectroscopy.

Twenty psychiatric patients on lithium medication were examined with 7-Li-magnetic resonance spectroscopy of the brain. Patients on long-term lithium treatment (> 6 months) were compared with a short-term group who had been taking lithium for between 4 and 8 weeks. Patients met DSM-III-R criteria for either recurrent unipolar depressive disorder (DSM-III-R 296.3x) or schizoaffective disorder, depressive type (DSM-III-R 295.70). The brain:serum lithium ratio was 0.76 +/- 0.26; there was no significant difference between short-term and long-term treatment. In the group of long-term treatment patients there was a positive correlation between lithium dose per day and brain lithium concentration (R = .72, p < .01), and between lithium plasma concentration and brain lithium concentration (R = .65, p < .05). In the short-term group, however, there was no significant correlation for these parameters. No differences between unipolar and schizoaffective disorder were found.

Adult↗
PubMed1997

[The central dopaminergic system and depression].

This review presents data supporting the involvement of the dopaminergic system in depressive illness. Neuroanatomical research, animal research and clinical studies have shown that a dysfunction of the mesolimbic dopaminergic system could be associated with depressive symptoms. Furthermore, the chronic administration of antidepressants in animals provokes a sensitisation and enhanced expression of dopaminergic receptors. Although the dopaminergic system has received little attention in biological research on depression in the last decades, current research on the dopaminergic system is about to change this situation

Animals↗
PubMed1997

The serotonin syndrome and psychosis-like side-effects of fluvoxamine clinical use--an estimation of incidence.

OBJECTIVE: The incidence of the serotonin syndrome or serotonin-syndrome-like side effects during treatment with the selective serotonin reuptake inhibitor (SSRI) fluvoxamine should be evaluated. METHOD: 200 inpatients treated for the first time with fluvoxamine were prospectively evaluated for the occurrence of a serotonin syndrome over a period of 8200 treatment days. Retrospective follow-up data of outpatient treatment covered 8891 days. RESULTS: No full-blown serotonin syndrome occurred, but 3 patients developed a reversible change of mental status with insomnia, agitation, confusion and incoherent thoughts without other symptoms of the serotonin syndrome. CONCLUSIONS: It is concluded that the occurrence of a potentially lethal serotonin syndrome is rare in fluvoxamine treatment psychosis-like syndromes as a side effect of serotonergic stimulation might occur. In the investigated sample the rate was 0.006-0.04 per 100 treatment days.

Adolescent↗
PubMed1997

Acceptance of a speech interface for biomedical data collection.

Speech interfaces have the potential to address the data entry bottleneck of many applications is the field of medical informatics. An experimental study evaluated the effect of perceptual structure on a multimodal speech interface for the collection of histopathology data. A perceptually structured multimodal interface, using speech and direct manipulation, was shown to increase speed and accuracy. Factors influencing user acceptance are also discussed.

Attitude to Computers↗
PubMed1997

[Overview of the most frequent clinical manifestations of peripheral arterial occlusive disease in the elderly, its diagnosis and stage-related therapy].

The peripheral artery occlusive disease is a widely spread disease and its diagnosis, treatment options and consequences are frequently underestimated. Especially for the old patient, preservation of an extremity may mean mobility and quality of life. The increasing life expectancy and behaviour of prosperity including a lack of mobility are causing a rise in the frequence of atherosclerotic diseases. The prevalence of occlusive vascular diseases in patients between 55 to 64 years of age is currently 11% and is, therefore, a wide-spread disease. However, the socio-economic relevance of the occlusive vascular diseases is frequently underestimated. It causes both very high direct costs (treatment procedures, prostheses etc) as well as high indirect costs (permanent disability). Therefore, early diagnosis and treatment plays an important role in the avoidance of a progression of the disease. For an early diagnosis of the stage I of occlusive vascular diseases it makes sense to examine the vessels of patients at risk (i.e. diabetes mellitus, hypertension, hyperlipidemia, nicotine abuse, and overweight). Dopplerultra-sound and oscillometry are highly sensitive and specific diagnostic measures. The eradication of risk factor and the treatment of the secondary diseases plays the most important role in this disease stage without symptoms. A specific vessel training is indicated during stage II to encourage the development of collateral blood flow. Additionally, an interventional diagnostic and therapy should be considered in this stage with limitations in the daily activities. The administration of vasoactive drugs is controversly discussed. The acetylsalicylic acid (ASA) is remaining the most investigated substance for reducing the progress of the arteriosclerotic process. The administration of ticlopidine is justified in cases of ASA-allergies. The stages III and IV are characterized by pain at rest and necrosis. Firstly, the indication for a transcutaneous transluminal angioplasty, thrombolysis or bypass-surgery should be proofed. If procedures of revascularization are not possible, prostaglandines may improve the pain at rest and wound healing. Beside the stage of the occlusive vascular disease, the presence of risk factors, the physical status of the patient, and the location of the occlusion are of great importance for the decision about the treatment procedure.

Adult↗
PubMed1996

Contributions of the mitogen-activated protein (MAP) kinase backbone and phosphorylation loop to MEK specificity.

To examine the specificity of MEKs for MAP kinase family members, we determined the abilities of several MEK isoforms to phosphorylate mutants of the MAP kinase ERK2 and the related kinase ERK3 which are modified in the phosphorylation loop. The ERK2 mutants included mutations of the two phosphorylation sites, mutations of the acidic residue between these two sites, and mutations that shorten the length of this loop. All mutants were tested for phosphorylation by six mammalian MEKs and compared with several wild type MAP kinases. MEK1 and MEK2 phosphorylate a majority of the ERK2 mutants. MEK2 but not MEK1 will phosphorylate ERK3. Alteration of the residue between the two phosphorylation sites neither dramatically affected the activity of MEK1 and MEK2 toward ERK2 nor conferred recognition by other MEKs. Likewise, reduction of the length of the phosphorylation loop only partially reduces recognition by MEK1 and MEK2 but does not promote recognition by other MEKs. Thus other yet to be identified factors must contribute to the specificity of MEK recognition of MAP kinases.

Amino Acid Sequence↗
PubMed1996

[Therapy with selective serotonin reuptake inhibitors (SSRI). Indications, uses and risks].

Indications, efficacy and side-effects of the selective serotonin reuptake inhibitors (SSRI) have now been investigated in numerous studies of varying quality. In the case of some disorders, SSRI have been shown to produce a very positive response-for example compulsive disorders and seasonal winter depression, so-called. In view of their effectiveness, SSRI are now considered first-line drugs for these indications. With respect to other disorders, SSRI are recommended because of their favorable side-effect profile. In further indications the efficacy reported in individual studies need further corroboration. Differences between individual SSRI, which mainly concern kinetics, are described.

Depressive Disorder↗
PubMed1996

The curse of the pharaoh: the evolution of virulence in pathogens with long living propagules.

We used a mathematical model to evaluate the hypothesis that parasites and pathogens with long living propagules should evolve high levels of virulence, i.e. high rates of pathogen-induced host mortality. Our model shows that the optimal level of virulence is independent of the longevity of the propagules either: (i) if the density or the prevalence of infected hosts is in (or fluctuates around) equilibrium; or (ii) if the death rate of the infected host population is high compared with that of the propagules. The level of virulence that maximizes the parasite's fitness (Multhusian parameter) increases with increasing longevity of its propagules only if the host-parasite system has not reached equilibrium and the death rate of the propagules is high relative to that of the infected hosts. Therefore, for parasites that have recently invaded a susceptible host population, greater propagule longevity may initially favour higher virulence; but once the equilibrium is reached the optimal virulence is independent of propagule longevity.

Animals↗