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Biomedical subjects

P Hirsch

Publications and source records attributed to P Hirsch.

At least 73 records · Page 4Linked to original sources
PubMed1988

Characterization of 15 selected coccal bacteria isolated from Antarctic rock and soil samples from the McMurdo-Dry Valleys (South-Victoria Land).

Approximately 1500 cultures of microorganisms were isolated from rocks and soils of the Ross Desert (McMurdo-Dry Valleys). From these, 15 coccoid strains were chosen for more detailed investigation. They were characterized by morphological, physiological and chemotaxonomical properties. All isolates were Gram-positive, catalase-positive and nonmotile. Six strains showed red pigmentation and could be identified as members of the genera Micrococcus (M. roseus, M. agilis) or Deinococcus. In spite of their coccoid morphology, the remaining nine strains had to be associated with coryneform bacteria (Arthrobacter, Brevibacterium), because of their cell wall composition and G+C ratios. Most of the strains were psychrotrophic, but one strain was even obligately psychrophilic, with a temperature maximum below 20 degrees C. Red cocci had in vitro pH optima above 9.0 although they generally originated from acid samples. Most isolates showed a preference for sugar alcohols and organic acids, compounds which are commonly known to be released by lichens, molds and algae, the other components of the cryptoendolithic ecosystem. These properties indicate that our strains are autochthonous members of the natural Antarctic microbial population.

Antarctic Regions↗
PubMed1988

[Pregnancy following in vitro fertilization and intratubal embryo transfer].

The intratubar embryotransfer is a variation of the in vitro fertilization, where the procreated preimplantation-embryos are not transferred into the cavum uteri but the tube(s). The intracavitar embryotransfer is the only possibility to treat irreparable tubar sterility in contrary to sterility not caused by the tubes where the transfer can be effected directly into the tubes. Considering the gamete intrafallopian transfer (GIFT) one can assume, that the tubes are the best physiological place for the very young embryo's evolution. In opposition to the GIFT-method the embryotransfer into the tubes will be done only if a fertilization was proved: thereby superfluous operations can be avoided and additional diagnostic hints can be gained. The valuable indications are the following ones: idiopathic sterility, certain cases of andrological subfertility and immunological sterility; probably for some kinds of the last indication from the intratubar embryotransfer there will result a special area of application. It is reported about a viable pregnancy after in vitro fertilization and intratubar embryotransfer. The new method is supposed to be called IVF/IT-ET (i.e. in vitro fertilization and intratubar embryotransfer).

Adult↗
PubMed1988

[Pregnancy following intratubal gamete transfer by hysteroscopy].

The method of gamete intrafallopian transfer (GIFT) was first described by Asch and has since the been introduced into the treatment of sterility not caused by the tubes. Standard technique for this method is laparoscopy. We report on the first pregnancy in our hospital when gamete intrafallopian transfer was undertaken hysteroscopically, i.e. combined with a transvaginal ultrasound-guided puncture of follicles for obtaining oocytes. The procedure is described. The important aspects of this technique are discussed briefly and the advantages shown: Shorter duration of intervention, reduced traumatisation of the patient and the possibility of effecting the operation without anaesthesia. The stress resulting from this technique is hardly different from that during intratubal embryo transfer provided this too is effected with sonographically monitored transvaginal follicle puncture.

Adult↗
PubMed1988

New bacteriophages active on strains of Hyphomicrobium.

Fifty-five lytic bacteriophages isolated from water and soil samples were active on many strains of the genus Hyphomicrobium. The optimal isolation procedure was an adsorption method in which samples from a habitat similar to that of the respective host bacterium were used as the phage inoculum. According to the morphology and nucleic acid type these bacteriophages belonged to different families: Myoviridae (type A1: five phages); Styloviridae (type B1: 33 phages; type B2: eight phages) and Podoviridae (type C1: nine phages). The Styloviridae (type B1) appeared in two morphological variants (tails flexible or rigid). All phages investigated were specific for the genus Hyphomicrobium and were unable to lyse members of other genera of hyphal, budding bacteria (e.g. Hyphomonas, Pedomicrobium, genus D, genus T). The host specificity of 42 phages was tested with 156 Hyphomicrobium strains: 122 strains were lysed by at least one of these phages, but 34 Hyphomicrobium strains were not susceptible. Morphotype B1 phages with identical morphology could be distinguished according to their host-range properties on prophage-containing Hyphomicrobium strains. With regard to differences in morphology and host range, 25 phages were selected for more detailed investigations. From these phages DNA was isolated; the melting transition midpoints (Tm) ranged from 67 to 93 degrees C. The upper and higher values suggested the presence of DNA modifications. Six different adsorption patterns could be distinguished among the Hyphomicrobium phages. Preferred attachment sites were the proximal pole of the mother cell, the hyphal tip, the distal pole of the bud, and the distal pole of the swarmer cell.

Bacteria↗
PubMed1988

Isolation and partial characterization of a bacteriophage active on Hyphomicrobium sp. WI-926.

Isolation of a Hyphomicrobium phage from raw sewage from Athens, Ohio, was achieved by a combination of differential centrifugation, filtration, enrichment in mixed Hyphomicrobium cultures, and purification on individual host strains by subculturing single plaques in soft agar overlayers. Enrichments with water from Lake Erie and Lake Beechwood (Ohio) were unsuccessful. Out of 21 Hyphomicrobium strains and 22 other Gram-negative and Gram-positive bacteria tested, only Hyphomicrobium WI-926 (isolated from a German forest pond) was susceptible. This phage had an isometric head (diameter between opposite apices, 67 nm) and a short (12 nm), noncontractile tail and belongs thus to the morphogroup C1. It contained double-stranded DNA. The single-step growth curve showed a latent period of 9 h, a rise period of 6 h, and a burst size of 35. The various differentiation stages in the host development exhibited different affinities for phage adsorption and development. While all stages allowed phage adsorption, the daughter cells were most efficient. Phage multiplication was limited to daughter cells, and the development of infected swarmer cells was arrested permanently at this stage.

Bacteria↗
PubMed1986

Microbial life at extremely low nutrient levels.

Many microorganisms ("oligotrophs") grow in distilled water: Pseudomonas spp., Caulobacter spp., Hyphomicrobium spp., Arthrobacter spp., Seliberia spp., Bactoderma alba, Corynebacterium spp., Amycolata (Nocardia) autotrophica, Mycobacterium spp., yeasts, and Chlorella spp. Also, certain lower fungi can be found here. In the laboratory, these organisms thrive on contaminations of the air (CO, hydrocarbons, H2, alcohols etc.). All are euryosmotic and often grow also in higher concentrations of salts and nutrients. Natural locations with extremely low nutrient levels (snow, rain water pools, springs, free ocean water, Antarctic rocks and soils) do not contain more than 1-5 mg/l of organic carbon. Oligotrophs found here are especially adapted to constant famine: they frequently live attached to surfaces, form polymers and storage products even while starving, and often aggregate. Many of these oligotrophs alter their morphology (surface to volume ratio) with changing nutrient concentrations. Extreme oligotrophs also occur in generally nutrient-rich environments such as sewage aeration tanks or compost soil. Here they are thought to survive in nutrient-depauperate microhabitats.

Bacteria↗
PubMed1982

Isolation and properties of ferromanganese-depositing budding bacteria from baltic sea ferromanganese concretions.

Hyphal budding bacteria were observed by electron microscopy in thin sections of surface material from Baltic Sea ferromanganese concretions. Similar bacteria were also observed in and isolated from enrichment cultures prepared from the same concretion material. Three morphologically similar strains of Mn-Fe-depositing budding bacteria were isolated from the enrichment cultures. Strain B-4 possessed extracellular anionic polymers that accumulated Mn oxides. Mn deposition by B-4 was inhibited by elevated concentrations of Mn, 0.05% glutaraldehyde, 0.1 mM HgCl(2), and heating at 93 degrees C for 15 min, suggesting the participation of an enzyme protein in the Mn-depositing activity.

Journal Article↗
PubMed1979

Neutron activation analysis for the demonstration of amphibolite rock-weathering activity of a yeast.

Neutron activation analysis was employed in a survey of weathering abilities of rock surface microorganisms. A yeast isolated from an amphibolite of a megalithic grave was found actively to concentrate, in media and in or on cells, iron and other elements when grown in the presence of ground rock. This was demonstrated by comparing a spectrum of neutron-activated amphibolite powder (particle size, 50 to 100 mum) with the spectra of neutron-activated, lyophilized yeast cells which had grown with or without amphibolite powder added to different media. The most active yeast (IFAM 1171) did not only solubilize Fe from the rock powder, but significant amounts of Co, Eu, Yb, Ca, Ba, Sc, Lu, Cr, Th, and U were also mobilized. The latter two elements occurred as natural radioactive isotopes in this amphibolite. When the yeast cells were grown with neutron-activated amphibolite, the cells contained the same elements. Furthermore, the growth medium contained Fe, Co, and Eu which had been solubilized from the amphibolite. This indicates the presence, in this yeast strain, of active rockweathering abilities as well as of uptake mechanisms for solubilized rock components.

Journal Article↗
PubMed1978

Aggressive basal cell carcinoma of the scalp.

Three examples of an unusually aggressive form of basal cell carcinoma in the skin of the scalp were treated surgically. The extent of each tumor was verified with gross and microscopic examination. The tumors invaded fat, muscle, fascia, and bone. Dural involvement was seen in one case. Light microscopy showed a marked variation in growth patterns and cytologic types from one portion of the tumor to another. Characteristics included a diffusely infiltrating pattern with a fibrotic stromal response, rare intraepidermal tumor nests, formation of occasional duct-like structures, poor cellular cohesion with single-life invasion through dermal collagen, perineural invasion, and pleomorphism with varying nuclear cytoplasmic ratios. Basaloid populations with peripheral palisading were seen in each tumor. These malignancies may be representative of an unusual basal cell carcinoma variant unique to the scalp.

Adult↗
PubMed1977

Morphology and ultrastructure of Crenothrix polyspora Cohn.

Naturally grown cell material of Crenothrix polyspora from the well of a waterworks was studied by means of phase-contrast and Nomarski interference microscopy as well as by transmission electron microscopy. The material consisted of clusters of sheathed filaments up to 2 cm long. Propagation forms observed were nonmotile, spherical cells that arose by simple ("macrogonidia") or multiple ("microgonidia") septation of the filamental tips. Ultrastructural analysis revealed Crenothrix to be procaryotic and gram negative, with several layers of sheath material surrounding the filaments. On thin sections, individual cells had elaborate membrane systems in the form of lamellar stacks. They resembled thylakoids of photosynthetic bacteria. Spectrophotometric analysis gave no indication of photosynthetic pigments. The cells also contained large hexagonal bodies, rod-shaped fibrillar elements, and polyphosphate granules.

Bacteria↗
PubMed1974

Budding bacteria.

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Bacteria↗
PubMed1973

First generation synchrony of isolated Hyphomicrobium swarmer populations.

A method is described for obtaining synchronously growing swarmer cell populations of Hyphomicrobium sp. strain B-522. This was accomplished by isolating young swarmers from random cultures by centrifugation and filtration. Cell multiplication occurred during 38% of the growth cycle in populations synchronized in this manner. Observations were made of the changes in cellular morphology which occurred during the growth cycle. Of the 14.25 h required for the doubling in cell numbers, an average of 5 h passed before the swarmer cells began to develop their hyphae. This time varied over a range of 10 h. The time interval between the beginning of hyphal development and the beginning of bud formation was 3.5 to 4.5 h. The maturation of the first buds and their separation from the mother cells were completed in 5.5 h. The duration of these steps is compared to those measured previously in agar slide cultures.

Bacteria↗
PubMed1973

Nuclear apparatus of Hyphomicrobium.

The nuclear apparatus of Hyphomicrobium sp. strain B-522 is examined by various microscopy and radiolabeling techniques to determine its behavior during the reproductive cycle of these bacteria. The young, swarmer cell contains a single nucleoid comprised of a deoxyribonucleic acid (DNA) molecule with a molecular weight of 3.1 x 10(9). After development of the swarmer into a mature mother cell with a hypha and bud, the nucleoid replicates and separates into two daughter nucleoids during the initial stages of bud formation. After further development of the bud, one of the daughter nucleoids in the mother cell is rapidly transferred through the hypha to the bud. Half of the old DNA strands pass to each consecutive generation of daughter cells, but only 43% of the stable ribonucleic acid is transferred. The role which the hypha plays in the developmental cycle of these bacteria is discussed, and a mechanism for nuclear transfer is proposed.

Adenine↗