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Biomedical subjects

M Gut

Publications and source records attributed to M Gut.

At least 19 recordsLinked to original sources
PubMed2001

The effect of dorsal raphe nucleus (DRN) lesions on the locomotor activity rhythm in mice.

The study employed electrical lesions of dorsal raphe nucleus (DRN) to determine the functional significance of those nuclei in the regulation of wheel-running activity rhythm in mice in light/dark (LD 12:12), constant light (LL), and constant dark (DD) conditions. The wheel-running records showed that raphe nucleus lesions resulted in few days' decrease in common activity and amplitude in LD. The activity phase was not compact but in fragmentary form, especially in DD condition. In some animals an earlier onset of activity after DRN lesion in LD was observed. In LL extension of the rhythm period occurred. Destruction of DRN only slightly modulates the wheel-running circadian rhythm in mice.

Animals↗
PubMed1999

A highly specific and sensitive competitive enzyme-linked immunosorbent assay (ELISA) based on baculovirus expressed pseudorabies virus glycoprotein gE and gI complex.

A direct competition enzyme-linked immunosorbent assay (ELISA) based on baculovirus expressed complex of pseudorabies virus (PRV) glycoproteins E (gE) and I (gI) has been developed. For that purpose gE and gI genes of PRV were co-expressed in insect cells. Complex formation was confirmed by radioimmunoprecipitation assay. The specificity and sensitivity of the test were evaluated and compared with an ELISA using only gE as an antigen and a commercially available test. For validation, 245 negative sera and 165 positive sera have been tested. The gE/gI ELISA had a higher sensitivity and specificity when compared with the ELISA using only gE as the antigen. Both sensitivity and specificity were comparable with the commercially available test. Moreover, the test based on the baculovirus gE/gI complex allows the detection of anti-gE antibodies in pig serum as early as two weeks after infection. The gE/gI ELISA test is easy to perform; its additional advantage is that the gE/gI antigen can be produced in baculovirus system in large quantities without handling live pseudorabies virus.

Animals↗
PubMed1999

One-tube fluorogenic reverse transcription-polymerase chain reaction for the quantitation of feline coronaviruses.

A one-tube reverse transcription-polymerase chain reaction (RT-PCR) for absolute feline coronavirus (FCoV) quantitation was developed. The assay is based on the 5' nuclease activity of the Thermus flavus (Tfl) polymerase and a fluorogenic probe which generates fluorescence when it is cleaved. The fluorogenic probe, also called TaqMan(TM) probe (Perkin Elmer, Foster City, USA), is an oligonucleotide designed to bind between the two PCR primers to the target cDNA and is labeled with a reporter and a quencher dye. In the intact probe, the quencher dye suppresses the fluorescence of the reporter dye by Forster-type energy transfer. During the polymerase extension steps the Tfl exonuclease activity cleaves the hybridised probe resulting in the generation of fluorescent emission of the reporter dye. The threshold cycle (C(T) value) indicates the increase of reporter fluorescence and is directly related to the initial amount of target cDNA or RNA, respectively. Fluorescence is monitored in real time after each cycle by a Perkin-Elmer ABI Prism 7700 Sequence Detector. After completion of amplification, the C(T) values of the samples are calculated back to a standard curve, generated by amplification of diluted standard molecules. The one-tube RT-PCR described below allows precise quantitation, is highly sensitive, rapid (no separate reverse transcription step and no post-amplification steps), easy to handle, allows for a high sample throughput, shows a very good reproducibility, and can be executed with a low risk of contamination. The design of the primers probe combination enables the detection of all known FCoV strains and is also useful for the detection of canine coronavirus, transmissible gastroenteritis virus and porcine respiratory coronavirus.

Animals↗
PubMed1998

[Case presentation in small animal medicine. What is your diagnosis?].

Atrial fibrillation and dilated cardiomyopathy were diagnosed in a 9-year old boxer who was examined because of anorexia and ascites. Longterm treatment included a diuretic (furosemide), an ACE-inhibitor (benazepril), digoxin, and a betablocker (atenolol). The prognosis for DCMP is unfavorable--the described dog died 11 months after diagnosis.

Animals↗
PubMed1986

Bile acid synthesis. Metabolism of 3 beta-hydroxy-5-cholenoic acid to chenodeoxycholic acid.

Metabolism of 3 beta-hydroxy-5-cholenoic acid to chenodeoxycholic acid has been found to occur in rabbits and humans, species that cannot 7 alpha-hydroxylate lithocholic acid. This novel pathway for chenodeoxycholic acid synthesis from 3 beta-hydroxy-5-cholenoic acid led to a reinvestigation of the pathway for chenodeoxycholic acid from 3 beta-hydroxy-5-cholenoic acid in the hamster. Simultaneous infusion of equimolar [1,2-3H]lithocholic acid and 3 beta-hydroxy-5-[14C]cholenoic acid indicated that the 14C enrichment of chenodeoxycholic acid was much greater than that of lithocholic acid. Thus, in all these species, a novel 7 alpha-hydroxylation pathway exists that prevents the deleterious biologic effects of 3 beta-hydroxy-5-cholenoic acid.

Animals↗
PubMed1985

Effect of P-450scc inhibitors on corticosterone production by rat adrenal cells.

Suspensions of rat adrenocortical cells produce corticosterone as the major glucocorticoid. Cholesterol side-chain cleavage, the initial and rate-limiting step in the glucocorticoid biosynthetic pathway, is catalyzed by P-450scc. We have examined the effect of a variety of P-450scc inhibitors on corticosterone production by isolated rat adrenocortical cells. These inhibitors include reversible, noncovalently interacting inhibitors as well as mechanism-based inhibitors which irreversibly inactivate P-450scc in vitro. (20S)-22-nor-22-thiacholesterol and (22R)-22-aminocholesterol cause 50% inhibition of corticosterone production at 4 microM and 30 nM, respectively. Inhibition by these compounds was essentially not time-dependent. (20R)-20-(1-hexynyl)-pregn-5-en-3 beta, 20-diol and (20R)-20-(1,5-hexdiynyl)-pregn-5-en-3 beta, 20-diol at 10 microM inhibited corticosterone production in a time-dependent manner, resulting in 30% inhibition of corticosterone production during a 100-min incubation. (20S)-20-(2-trimethylsilyl ethyl)-pregn-5-en-3 beta, 20-diol inhibited in a strongly time-dependent manner. At 10 microM this compound irreversibly inhibited more than 90% of the side-chain cleavage capacity of the cell during a 40-min incubation. Cells treated with this steroid did not regain their capacity for side-chain cleavage after removal of free steroid. None of the inhibitors described above inhibited production of corticosterone by cells supplied with pregnenolone, the product of the P-450scc reaction. We suggest that the only significant effect of these compounds under these conditions is inhibition of the side-chain cleavage enzyme.

Adrenal Cortex↗
PubMed1985

Competitive inhibition of cytochrome P-450scc by (22R)- and (22S)-22-aminocholesterol. Side-chain stereochemical requirements for C-22 amine coordination to the active-site heme.

Two diastereomeric aminocholesterols, (22R)-22-aminocholesterol and (22S)-22-aminocholesterol, are both found to be potent inhibitors of the biosynthesis of pregnenolone from cholesterol by purified bovine mitochondrial P-450scc. Both steroids are competitive versus cholesterol, but the stereochemically correct analog (22R)-22-aminocholesterol is bound approximately 1000 times more tightly than (22S)-22-aminocholesterol. The dissociation constants are 25 nM and 13 microM, respectively. Direct comparisons between spectroscopic and enzymatic properties of the two enzymesterol complexes and the 22-amino-23,24-bisnor-5-cholen-3 beta-ol complex are made, underlining the importance of the stereochemistry at the C-22 position.

Animals↗
PubMed1983

Synthesis of 3 alpha,7 alpha-dihydroxy-5 beta-androstan-17-one.

A short and efficient method for the stereospecific synthesis of 3 alpha,7 alpha-dihydroxy-5 beta-androstan-17-one was accomplished from the readily available 4-androstene-3,17-dione. Key steps are the stereospecific and selective epoxidation of 4,6-androstadiene-3,17-dione, followed by hydrogenations with carefully selected reagents, solvents and reaction conditions.

Androstenedione↗
PubMed1981

Bile acid synthesis. Metabolism of 3 beta-hydroxy-5-cholenoic acid in the hamster.

Synthesis of 3 beta-hydroxy-5-[1,2-3H]cholenoic acid has permitted a study of its metabolism in bile-fistula hamsters that received the compound by intravenous infusion. Metabolites in bile were identified by reverse isotope dilution after their complete resolution by high pressure liquid chromatography using muPorasil. Recovery of administered radioactivity ranged from 21-60% in three animals. In each study, lithocholic acid (0.8-4.4%) and chenodeoxycholic acid (7.8-11.3%) were identified as metabolites of 3 beta-hydroxy-5-cholenoate and can be considered primary bile acids in the side-chain pathway of bile acid synthesis beginning with the oxidation of cholesterol to 26-hydroxycholesterol.

Animals↗
PubMed1977

Specificity of the cholesterol side-chain cleavage enzyme system of adrenal cortex.

Incubation of lanosta-8, 24-dien-3beta-o1-1,2-3H and lanost-8-en-3beta-o1-1,2-3H with an adrenocortical bovine mitochondrial acetone-dried preparation did not yield any significant (less than 0.01%) 3beta-hydroxy-4, 4, 14-trimethyl-5alpha-pregn-8-en-20-one. Under the same conditions cholesterol-1,2-3H yielded 8.3% pregnenolone. Incubation of (20S)-17alpha, 20-di-hydroxycholesterol-7-3H yielded 0.6 to 1.6% (20S,22R)-17alpha, 20, 22-trihydroxycholesterol, 1.0 to 3.2% of 17alpha-hydroxy-pregnenolone, but no significant (less than 0.02%) (20S,22S)-17alpha,20,22-trihydroxycholesterol. In another experiment incubation of cholesterol-1,2-3H yielded 5% pregnenolone, 0.5% 17alpha-hydroxypregnenolone, 0.2% (20R,22R)-20,22-dihydroxy-cholesterol, but no significant ( less than 0.01%) 17alpha-hydroxy-cholesterol, (20S)-17alpha, 20-dihydroxycholesterol or (20S,22R)-17alpha, 20,22-trihydroxycholesterol.

Adrenal Cortex↗
PubMed1977

Bile acid synthesis in man. II. Determination of 7 alpha-hydroxycholesterol, (22R)-22-hydroxycholesterol, and 26-hydroxycholesterol in human meconium.

7 alpha-Hydroxycholesterol, (22R)-22-hydroxycholesterol and 26-hydroxycholesterol have been quantitated in human meconium. The method used tetrahydrofuran for extraction and solvolysis of the sulfate esters, liquid partition chromatography for the separation of the hydroxysterols, gas-liquid chromatography for quantitation, gas-liquid chromatography-mass spectrometry for identification, and tritiated and 14C-labeled tracers for overall recovery standards. (22R)-22-Hydroxycholesterol and 26-hydroxycholesterol were present almost entirely, ( greater than 93%) in the sulfate fraction at concentrations of 3.8-6.4 and 0.4-0.8 mg per 100 g meconium, respectively. Since free tritiated (22R)-22-hydroxycholesterol was used as the tracer to assess recovery of this hydroxysterol, the concentrations found for this compound may be minimal. Tritiated 26-hydroxycholesterol 3,26-disulfate was used as tracer to determine the levels of this compound, and the solvolysis procedure was optimized for recovery of 26-hydroxycholesterol and least decomposition of 7 alpha-hydroxycholesterol. No significant amounts of 7 alpha-hydroxycholesterol were found based on the tracer-free hydroxysterol as recovery standard.

Cholesterol↗
PubMed1976

Inhibition of the conversion of cholesterol to pregnenolone in bovine adrenocortical preparations.

The inhibition of the conversion of [4-14C] cholesterol to [4-14C] pregnenolone by a number of steroids has been studied in bovine adrenocortical mitochondrial acetonedried preparations. At equimolar substrate and inhibitor concentrations (3.3 muM) the most potent inhibitors were cholesterol derivatives containing a nitrogen function at c-22, followed by derivatives containing oxygen functions at c-22 or c-20 or both. The presence of a hydroxyl group at c-17 or the replacement of the 3beta-hydroxyl group by fluorine reduced the inhibitory efficacy. In the presence of inhibitors that were also relatively good substrates of the cholesterol side-chain cleavage system, such as some cholesterol derivatives hydroxylated in the side-chain,the rate of [4-14C] pregnenolone formation increased with time as the inhibitor was consumed. (20S)-20,21-Dihydroxycholesterol exerted such an effect on the kinetics of [4-14C]pregnenolone formation, and yielded 21-hydroxypregnenolone which was identified by gas chromatography-mass spectrometry. The synthesis of (20R)-22-ketocholesterol, of (20R,22R)-22hydroxycholesterol, (20R,22S)-hydroxycholesterol, and of (20S)-desmosterol is described.

Adrenal Cortex↗