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Biomedical subjects

H Hecker

Publications and source records attributed to H Hecker.

At least 127 records · Page 7Linked to original sources
PubMed1983

Sequential patterning of emotional interaction in families with a schizophrenic son.

In 30 families with a schizophrenic son conjoint family discussions which had been generated by Strodtbeck's "Revealed Differences Technique" were analyzed on the strength of the "Relationship-Scale" developed by Riskin and Faunce. All three members of the family triad (two parents and son) proved to be more hostile and rejecting than their parallels in a control group of families whose sons had been admitted because of an acute surgical condition. However, no significant difference could be ascertained in the sequential patterning of interaction assessed by means of time-series analysis. In both family groups Bernoulli processes predominated, i.e. there was no dependence between the sequentially recorded speech units. A 2-year follow-up of the schizophrenic patients showed a contradictory pattern of results. In families with re-hospitalized sons there was only a slight and statistically insignificant tendency towards more negative relationships but the sub-groups of families containing a schizophrenic son differed clearly on the level of sequential data; more families with re-hospitalized sons showed autoregressive (morphogenetic) or moving average (morphostatic) processes.

Adult↗
PubMed1983

Peritrophic membranes and protease activity in the midgut of the malaria mosquito, Anopheles stephensi (Liston) (Insecta: Diptera) under normal and experimental conditions.

Formation and solubility of the peritrophic membranes (pm) in the midgut (stomach) of female Anopheles stephensi depended on salt concentration in the gut lumen. High calcium drastically reduced the solubility of the pm in vitro. Thin-layer chromatography revealed the presence of N-acetylgalactosamine and galactose in the pm. In contrast to Aedes aegypti no N-acetylglucosamine was present indicating significant differences between Anopheles and Aedes mosquitoes with respect to pm formation and composition. Experimental distension of the stomach epithelium did not trigger secretion of proteases, but membrane-bound granules were released from the stomach cells, and pm were formed. When females were fed blood 18 hr after an enema with salt solution, when practically no granules were present in the gut cells, protease activity was increased, and blood was digested normally, but no pm were formed. A functional correlation of the membrane-bound granules and pm formation is postulated. alpha-Amanitin prevented normal digestion, protease activity was only insignificantly increased, and no pm formed after blood intake.

Animals↗
PubMed1983

The subcapsular hydrostatic pressure of allogeneic kidney grafts: a new clinical method for postoperative transplant monitoring.

A method for the measurement of the subcapsular hydrostatic pressure in human kidney grafts is described. This method permits follow-up studies over periods up to 4 weeks. First results indicate that the method is a useful tool to monitor the condition of renal allografts in the early postoperative period. It allows the early recognition of acute rejection episodes and predicts their course and reversibility. The subcapsular hydrostatic pressure is a particularly valuable parameter in the differentiation of acute rejection and acute tubular necrosis.

Acute Kidney Injury↗
PubMed1982

Azathioprine in treatment of multiple sclerosis. Final results of a 41/2-year controlled study of its effectiveness covering 115 patients.

In an open, randomised, controlled follow-up study the effectiveness of continuous azathioprine therapy of multiple sclerosis with a dosage of 2 mg/kg/day was tested against a control group that was not treated with cytostatics. In the treated group the disease progressed less rapidly than in the untreated group. Statistically significant differences were only seen in patients having an intermittent-progressive course. The effect of azathioprine on the course was not dependent on the period or severity of illness nor on the patient's sex. In chronically progressive disease and with an intermittent disease course no influence of azathioprine was observed.

Adult↗
PubMed1982

Comparative morphometric analysis of bloodstream and lymph forms of Trypanosoma (T.) brucei brucei grown in vitro and in vivo.

The fine structure of bloodstream forms of Trypanosoma brucei cultivated in vitro, and of trypanosomes from lymph and blood of mammalian hosts, was compared morphometrically. The cell volume, quantitative parameters of the mitochondrion and of glycosomes were mainly investigated. A Coulter Channelyzer was used for the first time to measure the mean cell volume of living parasites. In vitro, the monomorphic trypanosomes between the feeder layer cells showed lower values for mitochondrial parameters than the slightly pleomorphic forms from the supernatant medium. Trypanosomes in culture were very similar morphologically to forms from lymph nodes of rats. Despite some morphometric differences between cultivated blood stream forms and those grown in vivo, the similarity of both populations was clear. Both populations, however, differed significantly from stages found in the vector or from procyclic culture forms.

Animals↗
PubMed1982

Functional morphology of the midgut of a sandfly as compared to other hematophagous nematocera.

The midgut epithelium of female Lutzomyia longipalpis was investigated by means of electron microscopic morphometry before and during blood digestion. Ultrastructure and cytological changes of the stomach cells upon blood feeding were generally similar to the ones described for Phlebotomus longipes (Gemetchu, 1974) and for mosquitoes (Hecker, 1977). In addition, the quantitative composition of the cells resembled the one of mosquitoes in many respects. Despite some morphological differences in the functional gut cytology, it can be admitted that, in general, digestive processes may run similarly in the midguts of sandflies and mosquitoes.

Animals↗
PubMed1982

[Dose dependence of reproductive lethal cell damage after X-ray irradiation or exposition to adriamycin at low doses (author's transl)].

The effect exerted by X-rays, adriamycin and combined adriamycin and X-ray exposition on the median colony size differences (MCD) on synchronized or partially synchronized hypotetraploid CHO-T71 fibroblasts proves that the MCD method is much more sensible in low dose regions than the normally used colony survival test. In dose regions lower than 1 Gy, the MCD shows a linear dependence on the radiation dose. As compared to the effect exerted by the cytostatic drug alone, the combined effect of adriamycin and X-rays shows a dose factor of 0,4 for the logarithmically rising scope of MCD. The possible reduction of adriamycin doses applied hitherto together with an additional irradiation provides a possibility to diminish toxic side effects for the patient and to preserve the local therapeutic effect. The authors underline the suitability of the MCD method for delicate biologic measurements on human cells in order to replace expensive experimentation on animals effected in order to test the individual efficacy of therapeutic combinations of cytostatic drugs and to ameliorate the demonstration of teratogenic and carcinogenic substances and substances with other toxic effects at low active ingredient concentrations.

Animals↗
PubMed1981

Morphometric parameters of the midgut cells of Aedes aegypti L. (Insecta, Diptera) under various conditions.

Previous morphometric or biochemical investigations have yielded different data on the distribution of free and membrane-bound ribosomes in midgut cells of Aedes aegypti. In the present paper ribosomal distribution has been morphometrically analysed to determine whether different mosquito strains, different food and different narcosis used in these previous studies, and/or methodological errors, could account for the different results. Most of the cellular parameters in the stomach epithelium of female A. aegypti, strain Rockefeller, and their changes during blood digestion, are comparable to those measured for another Aedes strain (Segemaganga, Hecker and Rudin, 1979), and ae generally similar to those of Anopheles stephensi (Hecker 1978). Proteolytic activity against casein is similar for both Aedes strains with a maximum activity being registered around 30 h after a blood meal. During digestion of human serum there is no increase in the ratio of membrane-bound to free ribosomes, and no significant increase in the surface area of the rough endoplasmic reticulum or of the number of bound or free ribosomes. Proteolytic activity is distinctly lower than during blood digestion. Immobilization of mosquitoes prior to dissection by either narcosis or by shaking in a test tube has no significant influence on cellular parameters in females fed on sugar solution and investigated 3 days after emergence. It is concluded that the differences in ribosomal parameters previously obtained by morphometrical (Hecker and Rudin 1979) and biochemical (Gander et al. 1980) methods, can only partly be explained by the selection of different food for the mosquitoes, and must also have been caused by methodological inadequacies.

Aedes↗
PubMed1980

Characterization of Trypanosoma brucei isolated from lymph nodes of rats.

Forms of Trypanosoma brucei isolated from lymph nodes of cyclically or intravenously infected rats, at different stages of infection, were morphologically compared with the corresponding bloodstream forms. Unlike the pleomorphic bloodstream trypanosome population, the lymph node trypanosome population was essentially monomorphic and resembled the slender forms of the bloodstream. Values for the morphometric parameters indicated a position between the slender and the stumpy forms. The number of trypanosomes/ml of blood showed the well-known periodic fluctuations while the number of trypanosomes/g of lymph node remained fairly constant. Serology revealed that lymph node trypanosome populations differed antigenically from the trypanosome populations isolated simultaneously frrom the bloodstream.

Animals↗
PubMed1980

Distribution and attachment of Trypanosoma (Nannomonas) congolense in the proximal part of the proboscis of Glossina morsitans morsitans.

The distribution and attachment of Trypanosoma congolense were investigated in the proximal part of the proboscis of Glossina m. morsitans. In the food canal, epimastigotes and trypomastigotes formed tufts or compact layers. Trypanosomes were attached to the cuticle by their flagella, which formed zonar hemidesmosomes. The flagella were mostly attached parallel to the axis of the labrum and often pointed to its tip. Foot-like processes of the flagella came into contact with adjacent flagella leading to dense grouping of the trypanosomes. Despite narrow contacts between adjacent flagella, no desmosomes were differentiated. The trypanosomes were attached to all parts of the LCI sensilla and might thus impair their function. Uncoated and coated forms were present in the labrum, which indicated that transformation to metacyclic forms is not strictly limited to the hypopharynx. Uncoated forms were often attached to the cuticle of the common salivary duct and hypopharynx by hemidesmosomes. Coated forms could also be attached. Neither compact layers nor tufts of trypanosomes were found. This attachment may partly explain the low number of metacyclics deposited when flies probed on a warm glass slide.

Animals↗
PubMed1979

Functional morphology of the midgut of Aedes aegypti L. (Insecta, Diptera) during blood digestion.

Morphometric analysis of the epithelial lining of the stomach of A. aegypti suggests that digestion of the first blood meal in the stomach of this species can be viewed as a series of phases that can be correlated with physiological data from the literature. In phase Ia (0-10 h after blood meal [abm]) the whorls of the rough endoplasmic reticulum unfold, the Golgi zones increase, and the basal labyrinth is enlarged. This coincides with processes of synthesis and secretion (e.g., peritrophic membrane, esterases and lipases) and transport by the stomach epithelium. In phase Ib (10-20 habm) the cellular parameters measured further increase, indicating high synthetic and secretory activities (e.g., digestive enzymes). In phase Ic (20-30 habm) cell structures involved in synthesis and secretion still exhibit high values coinciding with maximal activity of proteases in the gut. Enhanced surface area of microvilli, prominent lipid inclusions, and appearance of glycogen deposits in the gut epithelium suggest increased absorption, storage, and transport functions of the stomach cells. In phase II (30-36 habm) structural alteration points to a gradual shift from synthesis and secretion to absorption, partial storage, and transport of nutrients. In phase III (36-72 habm) the cellular apparatus is reduced concomitant with the ending of the digestive cycle. Lipid inclusions and glycogen deposits disappear from the stomach epithelium.

Aedes↗
PubMed1979

Normal versus alpha-amanitin induced cellular dynamics of the midgut epithelium in female Aedes aegypti L. (Insecta, Diptera) in response to blood feeding.

In midgut epithelial cells (stomach) of untreated female A. aegypti an increase in the surface area of the rough endoplasmic reticulum (rer) and in the ratio of membrane-bound to free ribosomes is morphometrically measured during digestion of the first blood meal. This can be correlated with the synthesis and release of digestive proteases. The dynamics of the ribosomes in A. aegypti are similar to those in A. stephensi. 3 ng alpha-amanitin per mosquito prevent normal blood digestion, the proliferation of the rer and the increase in the ratio of bound to free ribosomes. On the other hand, some synthesis of new ribosomes takes place.

Aedes↗
PubMed1977

Ultrastructural changes in midgut cells of female Aedes aegypti L. (Insecta, Diptera) after starvation or sugar diet.

The ultrastructure of the epithelial cells in the posterior part of the midgut in female Aedes aegypti was partly changed after starvation periods of 5 or 8 days. Most obvious is a drastic reduction of the amount of rough endoplasmic reticulum (rer), which is responsible for the synthesis of enzymes for blood digestion. A similar influence on rer membranes is to be observed in mosquitoes fed on sucrose solution only, without additional blood meals.

Aedes↗
PubMed1976

Morphometric comparison of the midgut epithelial cells in male and female Aedes aegypti L. (Insecta, Diptera).

Midgut epithelial cells of male and female Aedes aegypti, 3 days after emergence, were compared morphometrically. The results of the present investigation concerning the female, are in good agreement with those of a previous study (Hecker et al., 1974), demonstrating that morphometric investigation of midgut epithelia in A. aegypti can successfully be reproduced, and that the mosquito strain used did not show quantitative morphological changes due to laboratory rearing. In males, the cells of the anterior (A) and posterior part (P, 'stomach') of the midgut differ in their quantitative composition. Higher values are found for the microvilli and for the basal labyrinth in the A-part. On the other hand a higher volume density of the mitochondria is present in the P-part. No significant differences are found in the A-part between males and females. Significant differences, however, are present in the P-part. Distinctly more rer in the female stomach can be correlated with the synthesis of enzymes for blood digestion, which are absent in the male. In addition, the more complex functions of the female P-part are also reflected by higher values for other organelles and membrane systems (e.g. mitochondria, basal labyrinth).

Aedes↗