PubMed Health⌕ Search

Biomedical subjects

J Weiser

Publications and source records attributed to J Weiser.

At least 19 recordsLinked to original sources
PubMed1996

The Effect of Bacillus thuringiensis M-exotoxin on Trematode Cercariae

The effect of Bacillus thuringiensis israelensis eluate containing water-soluble exotoxin (M-exotoxin) was observed by its use on cercariae of seven trematode species. To the most sensitive species to the toxic effect of the mentioned toxin belonged schistosome furcocercariae (human species Schistosoma mansoni and avian parasite Trichobilharzia szidati). Under the influence of the toxin, surface syncytial structure (tegument) was separated from underlying tissues, with subsequent disintegration of internal organs connected with disruption of acetabular glands and release of their proteolytic content.

Journal Article↗
PubMed1995

Protein profiles of Streptomyces aureofaciens producing tetracyclines: reappraisal of the effect of benzyl thiocyanate.

Cell protein profiles of submerged cultures of Streptomyces aureofaciens cultivated in the absence or presence of 12 microM benzyl thiocyanate (BT) were analyzed by one-dimensional SDS polyacrylamide gel electrophoresis. Substantial increase in the intensity of the 13, 35, 37, 60, and 100 kDa protein bands was observed in cultures treated with BT. Similar increase in the 35, 37, and 60 kDa bands was found in a mutant blocked in the last chlortetracycline biosynthesis step. Effect of BT on the solid medium-grown cultures was also observed, with a more intensive substrate mycelium pigmentation and alteration in the spore size and shape as the most characteristic features. Earlier studies of BT effect involving those on the stimulation of chlortetracycline biosynthesis are summarized and a possible signal-transducing mechanism is discussed from the point of view of adaptation of S. aureofaciens to the uncoupling of oxidative phosphorylation.

Bacterial Proteins↗
PubMed1994

In vitro measurement of translation accuracy of ribosomes isolated from streptomycin-resistant mutant of Streptomyces granaticolor.

Accuracy of activity of ribosome isolated from UV-light-induced streptomycin-resistant R-21 mutant of Streptomyces granaticolor was measured in an E. coli-derived system translating poly(U) with a high rate and accuracy. Ribosomes from the R-21 mutant strain were shown to be resistant to streptomycin and about two-fold more accurate than those from the wild type. The mutant strain was found to be resistant to 1000 mg/L streptomycin (Stm) during vegetative growth while it sporulated on agar plates containing only up to 200 mg/L of Stm. The growth rate of the R-21 mutant in complex liquid medium was indistinguishable from that of the wild-type strain.

Drug Resistance, Microbial↗
PubMed1994

Effect of Bacillus thuringiensis beta exotoxin on ultrastructures of midgut cells of Culex sitiens.

In midgut cells of Culex sitiens intoxicated with beta exotoxin of Bacillus thuringiensis, the microvilli are greatly reduced. In the cytoplasm there is progressive disarrangement of the membranes of the rough endoplasmic reticulum, first to spherules, and later to a granular mass. Minute vacuoles appearing in the cytoplasm are parts of the distorted labyrinth and remains of the Golgi membranes. There is no disintegration of the outer cell membrane, and no hypertrophy of goblet cells. Nuclei remain in their posterior position and there are no cytoplasmic autophagic vacuoles in the centre. Cells in the same part of the midgut differ in the degree of disorganization.

Adenosine↗
PubMed1993

Early experiences with microsporidia of man and mammals.

Comparative data are given of microsporidian infections in insects and mammals. Due to minute size and diffuse distribution in mammals microsporidia were recognized in vertebrates only during search for virus infections. Early infections with Encephalitozoon in rearings of laboratory animals contaminated many isolates of other protozoan infections. Old separate descriptions of microsporidia in mice, rabbits or dogs have to be reevaluated with modern methods of molecular analysis. Old cases of infection of man known now as Encephalitozoon chagasi or Encephalitozoon sp. Matsubayashi are not belonging to the genus Encephalitozoon and should be jointly studied with Nosema connori as eventually identical. With actual improvements of methods of diagnostics the net of detection of microsporidia in man should be extended on routine testing of urine, faecal samples, eye and nose biopsies and other materials including vaginal smears. The way of circulation of the infections in the host organisms must be studied.

Animals↗
PubMed1992

Bacillary epithelioid angiomatosis involving the liver, spleen, and skin in an AIDS patient with concurrent Kaposi's sarcoma.

The simultaneous findings of bacillary epithelioid angiomatosis and Kaposi's sarcoma of the skin with visceral hepatosplenic bacillary epithelioid angiomatosis is reported in a patient with acquired immune deficiency syndrome. Liver biopsy showed periportal peliotic spindle cell foci that initially were misinterpreted as Kaposi's sarcoma. After antibiotic therapy induced rapid clinical improvement, repeated liver biopsy showed resolution of the previously noted lesions. Although the violaceous skin lesions all appeared similar clinically, some resolved completely and some progressed. One of the latter was biopsied and had the histologic features of Kaposi's sarcoma. The differential diagnosis is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

The mosquitocidal activity of conidia of Tolypocladium tundrense and Tolypocladium terricola.

Tolypocladium tundrense and T. terricola UV-irradiated conidia exhibited acute toxicity to Aedes aegypti larvae in concentrations of 5 x 10(5) and 5 x 10(6) ml-1, respectively. Substances deposited on the surface of conidia following sporulation appear to be responsible for rapid intoxication and killing of mosquito larvae. Treatment of larvae with dried methanolic extract of the spores also induced a high level of mortality accompanied by the same histological changes, including vacuolization and subsequent destruction of mitochondria of the midgut cells. Cyclosporin A was identified as a predominant metabolite forming the spore surface layer.

Aedes↗
PubMed1992

Ultrastructural changes in Culex pipiens larvae treated with tolypin, the insecticidal metabolite of Tolypocladium inflatum gams (Deuteromycetes).

Tolypin, the insecticidal metabolite of the entomopathogenic fungus of the genus Tolypocladium, causes knock-down effect followed by high mortality in treated Culex pipiens molestus larvae. Histopathological changes accompanying the knock-down symptoms were similar in all tissues. Mitochondria, the main target in the cells, were destroyed and consecutively changed into vacuoles with the remains of cristae and lysed internal structures. Despite destruction of the internal content of individual organelles, the membranes of the cell surfaces, the endoplasmic reticulum, the nuclei, and the covering membranes of tissues and organs, were not affected and remained intact until final autolysis of the tissues. Some mitochondria in intoxicated cells were destroyed completely, but others remained intact and apparently structurally unchanged.

Animals↗
PubMed1991

Characterization of an asporogenous mutant of Streptomyces aureofaciens with increased resistance to several aminoglycoside antibiotics.

An asporogenous spontaneous mutant of Streptomyces aureofaciens named ASR1 was selected on streptomycin gradient plates. The mutant is very stable and differs in ultrastructure and morphology, it is prototrophic but it lost the ability to grow well on soybean extract medium and produces one-tenth tetracyclines of the parent. The ASR1 mutant has a 3-4-fold increased resistance to streptomycin and is cross-resistant to other aminoglycosides. Comparison of the protein profiles from both strains on SDS gels revealed a very low expression of a 29.5 kDa protein in the ASR1 mutant which is overexpressed in both vegetative cells and spores of the parental strain.

Aminoglycosides↗
PubMed1991

[Epidemiologic data of rupture of the fibular ligament of the upper ankle joint].

Epidemical studies of fibular ligament lesions of the ankle joint lateral ligamentous lesions at the ankle joint are one of the most accidental injuries. It is necessary to bestow great care on prevention and therapy to avoid after effects. We report about 150 cases of acute injuries of the fibular ligament lesions of the ankle joint in 1987 treated by surgery and followed up to explore the cause of injury, its dimensions, the groups of patients and time of accident. Corresponding to literature sports activities were mostly the reason of accidents followed by casional accidents and industrial accidents. Mainly young people suffered from this injury preferring men. The part of reruptures was 14%. In 61.3% both Lig. fibulotal. ant. and Lig. fibulocalc. were ruptured followed by isolated rupture of the Lig. fibulotal.ant. in 32.7% of the cases.

Adolescent↗
PubMed1991

Tolypocladium terricola sp. N., a new mosquito-killing species of the genus Tolypocladium Gams (Hyphomycetes).

A new entomopathogenic species of the genus Tolypocladium, T. terricola is described from a soil sample from Finalnd. From other known Tolypocladium species, T. terricola differs in morphology, production of secondary metabolites and possession of relatively strong mosquitocidal activity. The fungus is characterized by broad oval conidia (2.5 x 2 microns) with one pointed end which are produced in grape-like clusters, and are not firmly adherent. When treated with T. terricola, mosquito larvae show typical features of intoxication characterized by the concentration of larvae in the centre of cup, hanging by their siphons on the surface.

Animals↗
PubMed1991

Distinguishing benign and malignant melanocytic lesions with the AgNOR method.

A silver staining technique has recently been devised to aid in the differentiation between benign and malignant melanocytic lesions. This study showed a statistically significant difference between the staining of silver-nucleolar organizer regions (AgNORs) in melanocytic nevi and that of AgNORs in malignant melanomas.

Diagnosis, Differential↗
PubMed1991

Effect of ichthyomycin on the ultrastructure of tissues of Culex pipiens.

A new antibiotic ichthyomycin produced by Streptomyces sp. strain 1107 was tested for its toxicity and effect on the ultrastructure of tissues of larvae of Culex pipiens autogenicus. Concentrations used were 5 x 10(-7), 2.5 x 10(-7), 1.5 x 10(-7) and 1 x 10(-7) g ml-1. The mortality of larvae after 24 h exposure was 90, 30, 0 and 0%, and after 48 h was 100, 100, 87 and 0%, respectively. The effect of the antibiotic was most evident on mitochondria. They distended and ruptured with subsequent dissolution of their cristae. The microvilli of the brush border of the midgut cells and cell membranes were unchanged, and the peritrophic membrane remained coherent. Cisternae of the rough endoplasmic reticulum and microbodies filled the cytoplasm. Chromatin of the nuclei was aggregated into amorphous masses on the wall, but the nucleolus remained intact. Some cells showed large vacuoles in their cytoplasm from destroyed mitochondria. In muscle cells the mitochondria were in the process of dissolving and the sarcoplasmic reticulum formed elongate cisternae.

Animals↗
PubMed1990

How many EF-Tu molecules participate in aminoacyl-tRNA binding and peptide bond formation in Escherichia coli translation?

We have observed that two EF-Tu.GTP cycles are required to make one peptide bond during steady-state translation in an accurate and fast poly(U) translation system prepared from Escherichia coli. We have also found that there are two complexes of EF-Tu.GTP bound to one molecule of aminoacyl-tRNA under our experimental conditions. We suggest, on the basis of these data, that aminoacyl-tRNA enters the ribosomal A-site in a pentameric complex together with two EF-Tu and two GTP molecules. When the tRNA is delivered to the ribosome two GTP molecules are hydrolyzed. It is possible that the functional role of such an EF-Tu dimer is related to the function of the two L7/L12 dimers in the large ribosomal subunit.

Escherichia coli↗
PubMed1989

Content, distribution and stability of protein-synthesis elongation factor Tu in subcellular fractions of vegetative cells and spores of Streptomyces aureofaciens.

The protein synthesis elongation factor Tu (EF-Tu) was identified in dormant spores of Streptomyces aureofaciens and its content and distribution in vegetative cells and dormant spores were determined. Cell-free homogenates from spores were found to contain a EF-Tu cleaving membrane bound protease. The protease cleaved aggregated EF-Tu much less efficiently than non-aggregated factor in cell homogenates. The relative content of EF-Tu and ribosomes in dormant spores was very similar to that found in exponentially growing vegetative cells.

Cell Membrane↗
PubMed1989

Ultrastructural effects of macrotetrolides of Streptomyces griseus LKS-1 in tissues of Culex pipiens larvae.

The isolate of macrotetrolides produced by Streptomyces griseus strain LKS-1 was tested in its effect on the ultrastructure of larvae of Culex pipiens autogenicus. Changes were mainly in mitochondria where the cristae were destroyed and the outer membrane inflated. The endoplasmic reticulum was vacuolized and subsequently the nuclear membranes were seriously affected. Microvilli of the midgut epithelial cells and the surface membrane of these cells were unaltered and there were no changes in the arrangement of cells in the tissues. The effect of macrotetrolides on insect tissues is analogous to the effect of secondary metabolites of fungi such as beauvericin, destruxin E, cyclosporin or tolypin, and differs from the effects of bacterial endotoxins of Bacillus thuringiensis or B. sphaericus.

Animals↗