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Biomedical subjects

H Wetzel

Publications and source records attributed to H Wetzel.

89 records · Page 5Linked to original sources
PubMed1978

In vitro feeding in the rearing of tsetse flies (Glossina m. morsitans and G.p. palpalis, Diptera: Glossinidae).

The increasing demand for laboratory reared tsetse flies for research and biological control makes it necessary to develop effective and standardized tsetse fly feeding methods without using live animals for the daily blood uptake. The in vitro feeding technique, described in this paper, has been used for rearing G. m. morsitans by feeding them defibrinated equine blood through a silicone membrane. The results obtained for female longevity and productivity and mean weight of puparia are satisfactory. However, feeding defibrinated bovine blood results in significantly lighter puparia. A colony of G. p. palpalis feeding on defibrinated bovine blood is the only colony of this species that has been successfully maintained by in vitro feeding over several years. The survival rate of the females being fed defibrinated bovine, equine or porcine blood is equal. The number of larvae produced by females being fed defibrinated equine blood is significantly lower. Females younger than 50 days produce larvae which form a heavier puparia than females aged between 51 to 80 or 100 days, irrespective of blood source. Bovine blood used within the first 3 days after its collection leads to significantly higher mean weights of puparia than bovine blood used therafter. The increasing degree of haemolysis is most probably not the reason for this observation. A colony production model based on the performance of both species, G. m. morsitans and G. p. palpalis, fed in vitro, shows the importance of the first five age group periods (i.e. 45 to 50 days after emergence) for the overall performance of the flies. According to the results obtained, about 2,3 puparia per female are needed to maintain the same number of females in the colony. This level of production is reached in the fifth age group period. All larvae produced thereafter are available for colony expansion or experimental purposes. Rearing of both species with in vitro feeding is now a matter of routine.

Animal Feed↗
PubMedDate not supplied

Acute antagonism of dopamine D2-like receptors by amisulpride: effects on hormone secretion in healthy volunteers.

Amisulpride is a selective D2-like dopamine receptor antagonist with a high affinity for the cloned D2 and D3 receptors. At low doses it may improve depressive and negative schizophrenic symptoms whereas antipsychotic effects on positive schizophrenic symptomatology require higher dosages. Acute endocrine effects were studied for two doses of amisulpride with regard to the daytime secretion of prolactin, thyroidea stimulating hormone (TSH), growth hormone (GH), luteinizing hormone (LH) and cortisol. Amisulpride was administered i.v. to eight healthy male volunteers in a single-blind trial under a randomized cross-over, placebo-controlled design using doses of 20 mg or 100 mg, or saline. The drug was injected at 09:00 h, and plasma samples were withdrawn from 08:30 h to 16:00 h at intervals of 15 and 30 min, respectively. At both dosages, prolactin was significantly elevated to the eight- to ten-fold of baseline levels. Likewise, a significant 50% elevation of TSH concentrations with a trend to a greater increase under the 100 mg dose was observed. Plasma levels of LH and cortisol were not significantly affected by amisulpride. With regard to GH secretion, there was a trend to a decrease only with the 20 mg dose. These results indicate that the neuroendocrinological side-effect profile of acute amisulpride administration may be similar to conventional neuroleptics, and that there are only minor dose-dependent differential effects on hormone secretion in the dose range investigated.

Adult↗
PubMedDate not supplied

Primary enduring negative symptoms in schizophrenia and major depression.

Primary enduring negative symptoms (PENS) were studied in 26 patients with DSM-III-R schizophrenia and in 94 patients with unipolar major depressive episodes 5 years after the index episode. PENS were assessed with the Schedule for Deficit Syndrome (SDS). Negative symptoms were also assessed with the Scale for Assessment of Negative Symptoms (SANS) and subclassified into primary and secondary according to the SDS. The frequency of PENS did not differ significantly between schizophrenics and non-schizophrenic patients. Enduring negative symptoms (regardless of whether primary or not) were more frequently observed in schizophrenia (65% according to the SDS, and 88% according to the SANS) than in patients who had major depressive episodes (29% according to the SDS and 32% according to the SANS). By applying the SDS criteria for PENS, their frequency decreased in a manner which would probably affect the availability of patients samples for testing antinegative drugs. The results suggest that neither the negative symptomatology nor the primary enduring subtype ("deficit") is specific for schizophrenia. This finding might imply potential advantages of non-nosological, functional approaches for research into PENS.

Adult↗
PubMedDate not supplied

Three dimensions of depression in patients with acute psychotic disorders: a replication study.

Depressive symptoms in psychotic disorders are of high relevance but seem to be heterogeneous when assessed with a standard rating scale. The present analysis is a replication study on the dimensionality of the Bech-Rafaelsen Melancholia Scale (BRMES) in acutely psychotic patients with substantial depression defined according to a functional approach across the nosological borders of schizophrenia with major affective symptoms, schizoaffective disorder, depressed subtype, and major depression with psychotic features. The baseline data of 123 patients participating in a multicenter pharmacological trial were evaluated with structural equation models. A previously reported three-dimensional model of the BRMES comprising the facets retardation, depressive core symptoms, and accessory depressive symptoms was cross-validated by confirmatory factor analysis (CFA). The three-dimensional model proved to be superior to one-, two-, or four-factor models with respect to goodness-of-fit (goodness-of-fit index [GFI] = 0.91 and comparative fit index [CFI] = 0.89) and parsimony (adjusted GFI [AGFI] = 0.85). When comparing the present model with the previously reported model, a highly satisfactory correspondence emerged (CFI = 0.87). The results corroborate our previous findings that depression-like symptoms in acutely psychotic patients assessed by the BRMES can best be represented by a three-dimensional model and should not be treated as a homogeneous syndrome.

Acute Disease↗
PubMedDate not supplied

A randomized, double-blind comparison of a rapidly escalating dose of venlafaxine and imipramine in inpatients with major depression and melancholia.

A double-blind, randomized, parallel study in 167 hospitalized patients with major depression and melancholia was conducted to determine if rapidly escalated doses of venlafaxine produced an earlier response, compared with rapidly escalated doses of imipramine. The daily dose of venlafaxine was rapidly increased to 375 mg/day over a five-day period, was maintained at this level for 10 days, and then was reduced to 150 mg/day for the remainder of the study. The imipramine dose was rapidly increased to 200 mg/day over five days and was maintained at this level to the end of the study. The primary efficacy variables were time to response and time to sustained response on the HAM-D and MADRS. No differences in the response rates on the HAM-D or MADRS were observed between treatments. However, among patients who demonstrated a response on the HAM-D, there was a significantly faster onset of response (p = 0.036) and sustained response (p = 0.018) in the venlafaxine group. The median time to response on the HAM-D among responders was 14 days with venlafaxine and 21 days with imipramine. However, no differences between treatments were observed among responders on the MADRS (median time to response: 15 days for venlafaxine, 18 days for imipramine). Study events were reported in 69% of venlafaxine-treated patients and 76% of imipramine-treated patients. In severely depressed patients with melancholia, a faster onset of response was observed with venlafaxine on the HAM-D, but not the MADRS, and maximal tolerated doses of venlafaxine and imipramine were comparable for overall efficacy. These results confirm and extend previous observations and suggest that venlafaxine may have an early onset of action and may produce a rapid response in hospitalized patients with severe depression complicated by melancholia.

Adult↗
PubMedDate not supplied

Dimensionality of depression in acute schizophrenia: a methodological study using the Bech-Rafaelsen Melancholia Scale (BRMES).

Despite the great clinical importance of depressive symptoms in schizophrenia there is a lack of studies on the assessment and evaluation of depression in acutely psychotic patients. For the Bech-Rafaelsen Melancholia Scale (BRMES), among other advantages, the concept of unidimensionality was confirmed in patients with major depression by different methodological approaches including Rasch analysis. The present evaluation was designed to investigate the scale properties of the BRMES in acutely schizophrenic patients with particular emphasis on the dimensionality of the scale. Three different statistical approaches were used: principal component analysis in combination with computer simulation, polytomous Rasch analysis using advanced latent trait and latent class models and confirmatory factor analysis (CFA) by means of linear structure model approaches. The statistical methods were applied to BRMES baseline data of 132 acutely schizophrenic patients with predominantly positive symptoms participating in a multi-center pharmacological trial. The different methodological approaches revealed converging results indicating: (1) a substantial proportion of acutely ill schizophrenic patients showed depressive symptoms; (2) the hypothesis of unidimensionality of the BRMES had to be rejected for the sample of acutely schizophrenic patients and (3) a three-factorial model of depressive symptoms as measured by the BRMES ('retardation', 'depressive core symptoms', 'unspecific depressive symptoms') yielded the best fit of the present data. Depression in acutely psychotic patients has to be considered rather as a heterogeneous construct than as a well-defined syndrome. The differentiation of depressive symptomatology should facilitate treatment evaluation and help to clarify relationships between different symptom classes in further studies.

Adult↗
PubMedDate not supplied

The Calgary Depression Rating Scale for Schizophrenia: development and interrater reliability of a German version (CDSS-G).

A German version of the Calgary Depression Rating Scale for Schizophrenia (CDSS-G) approved by the author of the original scale is presented comprising a semi-structured interview for 9 items to sensitively and specifically assess depression in schizophrenia and related disorders. The process of translation is outlined and the finally derived CDSS-G was investigated with respect to interrater reliability in three studies. To keep comparability with the CDSS source version a standard procedure was used. Two trained raters jointly assessed ten schizophrenic patients (study I). In a second study, videotapes with the CDSS-G were presented to clinically inexperienced raters (study II, N = 14/15) to test the agreement on the CDSS-G in this sample. Finally, in a third study clinically experienced researchers participated in a rater training (study III, N = 34). They carried out CDSS ratings on three patients with mild depressive symptoms. The dependence of interrater reliability on depression severity was investigated for all studied patients. Both intraclass correlation coefficients (ICC) and weighted kappa coefficients (kappa(w)) were calculated. The results revealed a high ICC = 0.97 in study I for the total CDSS-G score. Single item ICC values were all above 0.70. The results of study II revealed somewhat lower agreement on CDSS-G items and total scores in psychiatric novices with however acceptable values of kappa(w)>0.50 for the total scores. Study III yielded satisfactory results (0.66<kappa(w)<0.76) for clinically experienced psychiatrists in schizophrenic patients with mild depression. The results demonstrate adequate to excellent interrater reliability of the CDSS-G corroborating the results of the original version in different settings.

Adult↗
PubMedDate not supplied

Adenylyl cyclase activity is increased in younger, but decreased in older, alcoholic patients after detoxification.

Acute and chronic administration of ethanol leads to alterations of the adenylyl cyclase (AC) signal transduction pathway. This study examined whether the formation of cAMP by AC in lymphocytes correlates with age in alcoholic patients and in healthy controls. Blood was drawn for preparation of lymphocyte membranes and for determination of basal, GTPgammaS-stimulated, and forskolin-stimulated AC activity from 68 actively drinking alcoholic patients (age, mean +/- SD: 45 +/- 10; range: 26-69 years) after ethanol detoxification. The patients' AC activity correlated negatively with age. In contrast, no effect of age was observed in the healthy controls (age, mean +/- SD: 42 +/- 11; range: 24-65 years). The age-related decrease in AC activity of alcoholic patients could not be attributed to the duration of regular alcohol intake. It was partly due to the large variance of AC activity in younger and middle-aged alcoholics.

Adenylyl Cyclases↗