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Biomedical subjects

G Vogt

Publications and source records attributed to G Vogt.

At least 37 records · Page 2Linked to original sources
PubMed1997

Spontaneous formation of intercellular bile canaliculi and hybrid biliary-pancreatic canaliculi in co-culture of hepatocytes and exocrine pancreas cells from carp.

When cultured together in a primary serum-free hormone-free system, hepatocytes and exocrine pancreas cells from the carp, Cyprinus carpio, spontaneously establish unique morphological structures that do not occur in vivo. These structures include intercellular bile canaliculi between neighbouring hepatocytes and hybrid canaliculi between hepatocytes and pancreas cells. In vivo, carp hepatocytes form only unicellular bile canaliculi; hybrid canaliculi between hepatocytes and exocrine pancreas cells do not exist at all in nature. This study shows that, in an artificial environment, cells are able spontaneously to establish novel morphological structures that are absent in the animal from which the cells have been obtained.

Animals↗
PubMed1997

Protein thermal stability: hydrogen bonds or internal packing?

Thermally stable proteins are of interest for several reasons. They can be used to improve the efficiency of many industrial processes and provide insight into the general mechanisms of protein folding and stabilization. Comparison of tertiary structural properties of several protein families with members of different thermostability should help to delineate the role of individual factors in achieving stability at high temperature. In this work, 16 protein families with at least one known thermophilic and one known mesophilic tertiary structure were examined for the number and type of hydrogen bonds and salt links, polar surface composition, internal cavities and packing densities, and secondary structural composition. The results show a consistent increase in the number of hydrogen bonds and in polar surface area fraction with increased thermostability.

Hydrogen Bonding↗
PubMed1997

A novel field generator for magnetic stimulation in cell culture experiments.

A novel field generator specially designed to examine the influence of low frequency magnetic fields on specific cell material was constructed and characterized. The exposure unit described in this paper consists of a controller unit and three sets of coils. The field generator permits a precious definition of the revelant signal parameters and allows the superposition of alternating current (AC) and direct current (DC) magnetic fields. Critical system parameters were monitored continuously. The three sets of coils, each arranged in the Helmholtz Configuration were characterized. After data processing and visualization the results showed a constant and homogeneous field within the experimental area. The special coil design also allows their use in an incubator.

Cell Physiological Phenomena↗
PubMed1996

Cytopathology of Bay of Piran shrimp virus (BPSV), a new crustacean virus from the Mediterranean Sea.

A new picorna-like or parvo-like virus was found in the hepatopancreas of the shrimp Palaemon elegans from the Bay of Piran (Mediterranean Sea). Bay of Piran shrimp virus (BPSV) infects preferably the R-cells of the hepatopancreas and to a lesser extent the F-cells. In R-cells it is abundant in the cytoplasm and within membrane whorls. In lesser numbers it can also be present in cell organelles like the endoplasmic reticulum, autophagosomes, or mitochondria. Less contrasting virus-like particles are observed in the nucleoplasm, suggesting a nuclear replication of the virus and completion of assembly in the cytoplasm. In F-cells the virus is located mostly in cisternae of the Golgi bodies. Occasionally, there are also virus clusters in the cytoplasm. B-cells are only rarely infected. The virus seems to invade the host cells from the lumen of the hepatopancreatic tubules through the microvillous border. Mature viruses are released again into the hepatopancreatic lumen by discharge of lytic epithelial cells. Individual viruses can also penetrate through the basal cell membrane into the hemal space. Occasionally, fixed phagocytes are attached to the basal lamina of heavily infected hepatopancreas cells, indicating an activation of the immune defense system by the virus.

Animals↗
PubMed1996

Morphology and physiology of digestive epithelia in Decapod crustaceans.

The anatomy and cellular composition of the digestive tract of decapod crustaceans is in many aspects considerably different from the vertebrate system. These differences include primarily the gastric mill and a sophisticated filter apparatus in the stomach and the hepatopancreatic tubule system with its bi-directional movement of fluids. Further differences are the lack of a strongly acidic pH and pepsin in the stomach. Consequently, many of the physiological processes are fundamentally different as well, particularly the physical and chemical processing of the feed and the synthesis, storage and mode of action of the digestive enzymes. The hepatopancreas is a central organ of metabolism and includes functions which, in vertebrates, are confined to intestine, liver and pancreas.

Animals↗
PubMed1996

Isolation of Thermus strains from hot composts (60 to 80 degrees C).

High numbers (10(7) to 10(10) cells per g [dry weight]) of heterotrophic, gram-negative, rod-shaped, non-sporeforming, aerobic, thermophilic bacteria related to the genus Thermus were isolated from thermogenic composts at temperatures between 65 and 82 degrees C. These bacteria were present in different types of wastes (garden and kitchen wastes and sewage sludge) and in all the industrial composting systems studied (open-air windows, boxes with automated turning and aeration, and closed bioreactors with aeration). Isolates grew fast on a rich complex medium at temperatures between 40 and 80 degrees C, with optimum growth between 65 and 75 degrees C. Nutritional characteristics, total protein profiles, DNA-DNA hybridization (except strain JT4), and restriction fragment length polymorphism profiles of the DNAs coding for the 16S rRNAs (16S rDNAs) showed that Thermus strains isolated from hot composts were closely related to Thermus thermophilus HB8. These newly isolated T. thermophilus strains have probably adapted to the conditions in the hot-compost ecosystem. Heterotrophic, ovalspore-forming, thermophilic bacilli were also isolated from hot composts, but none of the isolates was able to grow at temperatures above 70 degrees C. This is the first report of hot composts as habitats for a high number of thermophilic bacteria related to the genus Thermus. Our study suggests that Thermus strains play an important role in organic-matter degradation during the thermogenic phase (65 to 80 degrees C) of the composting process.

Environmental Microbiology↗
PubMed1995

An assessment of amino acid exchange matrices in aligning protein sequences: the twilight zone revisited.

The sensitivity of most protein sequence alignment methods depends strongly on the quality of the comparison matrices used. These matrices, which assign weights or similarity scores to every possible amino acid substitution pair, are utilized to differentiate amongst the various possible alignments of two or more sequences. There are many ways to generate these exchange weights and new matrices are constantly published. There has been no overall assessment of these various matrices when applied in different alignment techniques and over many protein folds and families, both close and distant and with the use of several gap penalty values. In this work, a set of amino acid sequences matched by superposition of known protein tertiary topologies is used to test the alignment accuracy of the different method/matrix/penalty combinations. The comparisons show relatively similar results for the top scoring matrices, a preference for the global alignment method of Needleman and Wunsch, and the importance of matrix modification and optimized gap penalties. The relationship between the percentage identity in a resulting alignment and the level of correctness to be expected are given for the top-performing matrix, resulting in a better definition of the so-called "twilight zone". Estimates are made for the probability that two sequences, aligned at a certain level of residue percentage identity, are in fact unrelated.

Amino Acid Sequence↗
PubMed1995

Heterologous HIV-2 challenge of rhesus monkeys immunized with recombinant vaccinia viruses and purified recombinant HIV-2 proteins.

In an attempt to analyse the role of anti-envelope immunity in the protection of rhesus monkeys against an HIV-2 intravenous challenge, rhesus macaques were immunized twice with recombinant HIV-2 ROD vaccinia viruses (10(8) p.f.u. each) at days 0 and 30, followed by booster injections of purified HIV-2 proteins at months 8, 9, 15 and 27. One group of five macaques was immunized with the Gag, Pol, Vif and Nef antigens, whereas a second group received the same antigens with the addition of HIV-2 Env protein. Eight months after the last boost, the animals were challenged by intravenous injection of 100 AID50 of a monkey PBMC-grown stock of HIV-2 SBL. None of the animals was protected in spite of high humoral immune responses on day of challenge as determined by ELISA and Western Blot assays.

AIDS Vaccines↗
PubMed1995

X-linked juvenile retinoschisis (RS) maps between DXS987 and DXS443.

X-linked juvenile retinoschisis (RS) has previously been localized to a 7-8 cM interval between markers at (DXS43, DXS207) and (DXS274, DXS41). Our analysis of more than 300 meioses in two multigeneration RS families identified eight recombinant RS chromosomes and narrowed the RS locus to an interval between DXS987 and DXS443. Our data suggest the following order of loci: Xpter-DXS207-DXS987-([DXS418-DXS999], RS)-DXS443-DXS365-DXS274-Xcen.

Base Sequence↗
PubMed1994

Induction of humoral and cellular immunity to simian immunodeficiency virus: what are the requirements for protection?

In an effort to produce a strong humoral and cellular immune response that might protect against simian immunodeficiency virus (SIV) infection, groups of five rhesus macaques each were immunized intramuscularly at 0, 2 and 6 months with 100 micrograms of an inactivated preparation of SIV/Delta B670 in either an oil-in-water emulsion with Ribi Detox, containing mycobacterial cell wall skeleton and monophosphoryl lipid A (CWS/MPL) (group A) or a water-in-oil emulsion with incomplete Freund's adjuvant, containing CWS/MPL for the first two injections (group B). Animals were challenged with 10-100 monkey ID50 of monkey-cell-grown SIVmac251 3 months after the last injection, along with a group of four unvaccinated controls. Group B animals demonstrated the strongest immune responses following immunization, including neutralizing antibody titres against the challenge virus ranging from 160 to 320 and SIV-specific ELISA titres ranging from 10(5)-10(6) on the day of challenge, as well as strong in vitro lymphoproliferative and interleukin-2 (IL-2) production responses to the immunogen. Neutralizing antibody was not detectable in group A animals, ELISA titres were lower (10(2)-10(4)), no in vitro lymphoproliferative responses were observed, and in vitro IL-2 production was less pronounced. No protection against challenge was observed in either group. Moreover, group B animals exhibited a more pronounced clinical response following challenge than either group A animals or controls, consisting of hyperthermia and a greater degree of lymphadenopathy on day 7, followed by hypothermia and generally higher levels of serum viraemia on day 14.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Sorsby's fundus dystrophy is genetically linked to chromosome 22q13-qter.

Sorsby's fundus dystrophy (SFD) is an autosomal dominant macular degeneration developing in the third or fourth decade. Patients lose central vision from subretinal neovascularization and atrophy of the choriocapillaris, pigment epithelium and retina. SFD shares some striking clinical features with age-related macular degeneration (AMD), the most common cause of blindness in western countries thereby providing a valuable genetic model for AMD. To map the SFD locus, we performed linkage analysis in a single large SFD family. After exclusion of approximately 65% of the autosomal genome, we found significant linkage to several markers from chromosome 22. Recombinant chromosomes sublocalize the SFD gene to 22q13-qter between D22S275 and D22S274.

Chromosomes, Human, Pair 22↗
PubMed1994

Mutations in the tissue inhibitor of metalloproteinases-3 (TIMP3) in patients with Sorsby's fundus dystrophy.

The hereditary macular dystrophies are progressive degenerations of the central retina and contribute significantly to irreversible visual loss in developed countries. Among these disorders, Sorsby's fundus dystrophy (SFD), an autosomal dominant condition, provides an excellent mendelian model for the study of the genetically complex age-related macular degeneration (AMD), the most common maculopathy in the elderly. Recently, we mapped the SFD locus to 22q13-qter. This same region contains the gene for tissue inhibitor of metalloproteinases-3 (TIMP3), which is known to play a pivotal role in extracellular matrix remodeling. We have now identified point mutations in the TIMP3 gene in affected members of two SFD pedigrees. These mutations are predicted to disrupt the tertiary structure and thus the functional properties of the mature protein.

Amino Acid Sequence↗
PubMed1994

Evolution of the human immunodeficiency virus type 2 envelope gene in preimmunized and persistently infected rhesus macaques.

The V3 and V4 domains of human immunodeficiency virus type 2 (HIV-2) env genes from 14 rhesus macaques experimentally infected by HIV-2 SBL6669/H5 were sequenced. No variation was observed in viral sequences from sera and from uncultured peripheral blood mononuclear cells during primary infection. The first mutations were detected 17 months after infection; they mainly concerned the region between the V3 and V4 domains and not those domains themselves, which are known to be hypervariable, suggesting that variation of V3 is a late event of HIV infection.

AIDS Vaccines↗
PubMed1994

High-resolution meiotic and physical mapping of the best vitelliform macular dystrophy (VMD2) locus to pericentromeric chromosome 11.

Best vitelliform macular dystrophy (VMD2) has previously been linked to several microsatellite markers from chromosome 11. Subsequently, additional genetic studies have refined the Best disease region to a 3.7-cM interval flanked by markers at D11S903 and PYGM. To further narrow the interval containing the Best disease gene and to obtain an estimate of the physical size of the minimal candidate region, we used a combination of high-resolution PCR hybrid mapping and analysis of recombinant Best disease chromosomes. We identified six markers from within the D11S903-PYGM interval that show no recombination with the defective gene in three multigeneration Best disease pedigrees. Our hybrid panel localizes these markers on either side of the centromere on chromosome 11. The closest markers flanking the disease gene are at D11S986 in band p12-11.22 on the short arm and at D11S480 in band q13.2-13.3 on the proximal long arm. This study demonstrates that the physical size of the Best disease region is exceedingly larger than previously estimated from the genetic data, because of the proximity of the defective gene to the centromere of chromosome 11.

Base Sequence↗
PubMed1994

Mimosine-induced cell death and related chromatin changes.

The non-protein amino acid mimosine has recently been shown to induce an unusual mode of cell death that differs from necrosis and apoptosis, the two fundamental schemes of cell death. The drug affects primarily the cell nucleus and induces first condensation of the chromatin into a regular network of fibrils and then gradual decondensation. The present study was performed to evaluate effective mimosine concentrations, time dependency of toxicity, and mimosine-related alterations of the chromatin, DNA and histones. To this end, primarily cultured carp hepatocytes were exposed to a wide range of mimosine (10(-1) to 10(-4) M) up to 12 h and investigated by means of light microscopy, electron microscopy, and histochemistry for DNA and histones. With 10(-1) M mimosine severe cytopathological transformations were obtained already after 3 h whereas 10(-2) M was cytotoxic only after 12 h. Lower concentrations were ineffective within the experimental period. Cytopathology started with condensation of the chromatin into a homogeneous network of ca. 25 nm wide fibrils and segregation of the nucleolus. In parallel, the nuclei were depleted from histones leaving the pattern of DNA fluorescence largely unchanged. The following period of chromatin decondensation was characterized by removal of electron-dense components from the condensed chromatin fibrils and gradual loss of the DNA. The segregated nucleolus and also the nuclear pores remained well preserved until final cell lysis.

Animals↗
PubMed1993

The two isoforms of the mouse somatostatin receptor (mSSTR2A and mSSTR2B) differ in coupling efficiency to adenylate cyclase and in agonist-induced receptor desensitization.

The somatostatin receptor 2 (mSSTR2) is alternatively spliced into two isoforms (mSSTR2A and mSSTR2B) which differ at the C-terminus. Both receptors bind somatostatin peptides with a similar high affinity when stably expressed in CHO-K1 cells. However, the spliced form (mSSTR2B) mediates a more efficient inhibition of adenylate cyclase and is much more resistant to agonist-induced reduction of binding than the longer form (mSSTR2A). These findings indicate that alternative splicing may be a physiological mechanism to modulate receptor desensitization and G-protein coupling of mSSTR2.

Adenylate Cyclase Toxin↗
PubMed1993

Profile sequence analysis and database searches on a transputer machine connected to a Macintosh computer.

An implementation of Profilesearch (a technique to search for relationships between a protein sequence and multiply aligned sequences) for a parallel computer is described. The number-crunching machine, consisting of 21 T800 transputers, is connected to a Macintosh IIcx host computer. The program utilizes a standard Macintosh application as its user-interface, resulting in a transparent and user-friendly environment for addressing the parallel computer. The program is independent of the number of available processors and exceeds the speed of a VAXstation 3200 with only one transputer in operation, thus allowing cheap and fast database searches with a PC front-end. For a larger number of processors, the speed increase is approximately linear with no obvious symptoms of saturation with the available maximum of 21 transputers. The program and environment are useful to search quickly and easily for similarities between a single sequence or sequence set and individual sequences contained in a large database. The alignment is determined by typical dynamic programming techniques.

Amino Acid Sequence↗