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Biomedical subjects

A Hoffmann

Publications and source records attributed to A Hoffmann.

At least 199 records · Page 11Linked to original sources
PubMed1996

Cholesterol lowering action of HOE 402 in the normolipidemic and hypercholesterolemic golden Syrian hamster.

The potent hypolipidemic activity of HOE 402 (4-amino-2-(4, 4-dimethyl-2-oxo-1-imidazolidinyl)pyrimidine-5-N-(trifluoromethyl-phenyl ) carboxamide monohydrochloride), which was previously demonstrated in rat and rabbit, was investigated in noncholesterol and cholesterol fed male hamsters. In normolipidemic hamsters fed a low cholesterol chow diet containing 0.10% or 0.15% HOE 402 for 3 weeks, the plasma total cholesterol level fell by 13% and 20% respectively, but no effect on hepatic total cholesterol content was detected. Hepatic sterol synthesis was increased 3-fold in hamsters fed 0.15% HOE 402. In hamsters fed a chow diet containing 0.25% cholesterol for 3 weeks, the plasma cholesterol level increased to 226 mg/dl (compared to 123 mg/dl in their chow fed controls) and the liver cholesterol content was 26.2 mg/g compared to 2.3 mg/g in the control group. However, 0.15% HOE 402 led to a 48% reduction and 0.20% HOE 402 to a 80% reduction, in total hepatic cholesterol concentration. There was a 43% fall in plasma cholesterol level being observed with the higher HOE 402 dose. Using the dual isotope plasma ratio method, no inhibition of intestinal cholesterol absorption by HOE 402 was found, either in the noncholesterol fed or in the cholesterol fed hamsters. Cholesterol feeding diminished the whole LDL animal clearance to 393 +/- 17 microliters/h per 100 g animal (control 666 +/- 81 microliters/h per 100 g). When treated with 0.20% HOE 402, the whole animal LDL clearance rate was enhanced 2.3-fold to 824 +/- 66 microliters/h per 100 g. In the hamsters fed 0.25% cholesterol alone whole liver LDL receptor activity was suppressed to 63 +/- 5%, compared to that in the untreated controls (100%). The addition of 0.20% HOE 402 to the cholesterol enriched diet not only reversed this suppression, but resulted in a marked stimulation of liver receptor activity to 165 +/- 15% (whole body LDL receptor activity 141 +/- 10%). These results indicate that HOE 402 exerts its lipid lowering effect by a more direct activation on hepatic LDL receptor activity rather than by an indirect intestinal effect on cholesterol absorption.

Animals↗
PubMed1996

Developmental expression of murine Beta-trace in embryos and adult animals suggests a function in maturation and maintenance of blood-tissue barriers.

The complete cDNA for murine Beta-trace protein was isolated by RT-PCR using degenerate primers designed according to amino acid sequences derived from tryptic peptides. It encodes a protein of 165 amino acids (calculated molecular weight 18,472 Da) with a predicted 24-amino-acid leader peptide. In situ analyses during mouse embryonic development and in adult animals revealed a specific temporal expression pattern of Beta-trace. Beta-Trace mRNA was initially detected at 14.5 days postconception in mesenchymal cells destined to become leptomeninges and in the developing testis. Later in development, a lower level of expression was additionally observed in choroid plexus epithelium, in strictly confined regions of the eye (pigment and ciliary epithelium), in the ear (cochlear duct), and within single cells in the brain. Expression was also found in epithelia of the epididymis and the testis Leydig cells of postpubertal animals. The highly specific expression at blood-tissue barriers such as the blood-cerebrospinal fluid, blood-retina blood-aqueous humor, and blood-testis barriers indicates a potential role for this lipocalin in transport and/or in maturation and maintenance of these barriers.

Amino Acid Sequence↗
PubMed1996

Constitutive secretion of beta-trace protein by cultivated porcine choroid plexus epithelial cells: elucidation of its complete amino acid and cDNA sequences.

Primary porcine choroid plexus epithelial cells cultivated in chemically defined medium maintain their epithelial characteristics and form confluent monolayers. They produce a fluid the composition of which resembles cerebrospinal fluid. The present study demonstrates constitutive secretion of large amounts of beta-trace protein. This intrathecally synthesized protein is a prominent polypeptide constituent of natural cerebrospinal fluid. According to the identity of amino acid sequences it has previously been tentatively identified as a prostaglandin-D synthase and as a member of the lipocalin protein family. beta-Trace was purified from cell culture supernatants and was subjected to tryptic digestion and amino acid sequencing of the resulting peptides. The complete primary structure of the protein was obtained by additional isolation of the cDNA from cultured epithelial cells. The porcine 163-amino acid polypeptide showed 69% identity with the human beta-trace and contained two N-glycosylation sites occupied by complex-type oligosaccharides as is the case for the human protein. The amino acid sequences around the N-glycosylation sites of mammalian beta-trace proteins (porcine, human, murine, and rat) were highly conserved. The nucleotide sequence was found to be less conserved; the porcine cDNA had a strikingly high GC-content (67%). The constitutive secretion of beta-trace protein from the in vitro cultivated porcine choroid plexus epithelial cells demonstrates that the cells have retained their major in vivo physiological properties: secretion of cerebrospinal fluid proteins. Therefore, this in vitro culture system may be used as a versatile tool for studying the regulation of the formation of cerebrospinal fluid.

Amino Acid Sequence↗
PubMed1996

Limited heterogeneity of rearranged T cell receptor V alpha and V beta transcripts in synovial fluid T cells in early stages of rheumatoid arthritis.

OBJECTIVE: The identification of activated T cells in synovial fluid and synovium, and the association of rheumatoid arthritis (RA) with specific HLA-DR restriction elements, strongly suggest that these T cells play a critical role in the etiology and pathogenesis of RA. Analysis of the T cell receptor (TCR) repertoire in the early stages of RA might be an approach to identify those T cells involved in the initiation and/or perpetuation of the disease. METHODS: TCR V alpha and V beta transcripts of synovial T cells, sampled at the early stages of RA, were amplified by reverse transcriptase-polymerase chain reaction. HLA-DR subtyping was determined by serologic analysis and dot-blot hybridization of polymerase chain reaction amplification products using digoxigenin-labeled, sequence-specific oligonucleotide probes. RESULTS: Our findings showed a limited heterogeneity of V alpha and V beta TCRs in synovial fluid T cells, and a preferential usage of TCR V alpha 17 in early RA. In contrast, in the later stages of RA, a more polyclonal TCR V alpha and V beta gene usage was observed. CONCLUSION: Our results support the view that induction of RA is driven by an oligoclonal immune response to an unknown antigen. These findings also suggest a pathogenetic role for V alpha 17 T cells in the early stages of RA.

Adult↗
PubMed1996

Use of alfentanil for in vitro fertilization oocyte retrieval.

STUDY OBJECTIVES: To determine alfentanil levels with a specific radioimmunoassay in serum and ovarian follicular fluid. DESIGN: Observational study. SETTING: University hospital. PATIENTS: 14 ASA status I women undergoing oocyte retrieval for in vitro fertilization. INTERVENTIONS: General anesthesia was induced with alfentanil 15 micrograms/kg and midazolam 2 mg and maintained with alfentanil 0.5 mg, 60% nitrous oxide (N2O) in oxygen (O2) and midazolam up to a total of 4 mg. Oocyte retrieval was performed using a transvaginal ultrasound guided technique, 34 to 36 hours after human chorionic gonadotrophin administration. MEASUREMENTS AND MAIN RESULTS: Mean procedure time for oocyte retrieval was 18 +/- 2.4 (SEM) minutes. All patients were fully awake within 5 minutes and all patients except one were able to move from the operating table to the stretcher with minimal help. Mean total protein concentration in the follicular fluid was 3.8 +/- 0.4 mg%. Maximal serum alfentanil concentrations (Cmax) were attained 5 minutes after start of the procedure (tmax) and were 92 +/- 20 ng/ml. In contrast, alfentanil concentrations in the follicular fluid increased constantly throughout the procedure up to 8.9 +/- 0.8 ng/ml at 15 minutes. Clinical pregnancy rate was 3 of 14 patients. CONCLUSION: It is evident that during the oocyte retrieval procedure, the alfentanil concentrations in the follicular fluid are about ten-fold smaller than the serum alfentanil concentrations at the same time points. Similar pharmacokinetics have been shown when propofol was used as anesthetic. The low accumulation of alfentanil in the follicular fluid increases the attractiveness of alfentanil for anesthesia during oocyte retrieval for in vitro fertilization.

Adult↗
PubMed1996

Mice lacking both subunits of lysosomal beta-hexosaminidase display gangliosidosis and mucopolysaccharidosis.

The GM2 gangliosidoses, Tay-Sachs and Sandhoff diseases, are caused by mutations in the HEXA (alpha-subunit) and HEXB (beta-subunit) genes, respectively. Each gene encodes a subunit for the heterodimeric lysosomal enzyme, beta-hexosaminidase A (alpha beta), as well as for the homodimers beta-hexosaminidase B (beta beta) and S (alpha alpha). In this study, we have produced mice that have both Hexa and Hexb genes disrupted through interbreeding Tay-Sachs (Hexa-/-) and Sandhoff (Hexb-/-) disease model mice. Lacking both the alpha and beta-subunits these 'double knockout' mice displayed a total deficiency of all forms of lysosomal beta-hexosaminidase including the small amount of beta-hexosaminidase S present in the Sandhoff disease model mice. More surprisingly, these mice showed the phenotypic, pathologic and biochemical features of the mucopolysaccharidoses, lysosomal storage diseases caused by the accumulation of glycosaminoglycans. The mucopolysaccharidosis phenotype is not seen in the Tay-Sachs or Sandhoff disease model mice or in the corresponding human patients. This result demonstrates that glycosaminoglycans are crucial substrates for beta-hexosaminidase and that their lack of storage in Tay-Sachs and Sandhoff diseases is due to functional redundancy in the beta-hexosaminidase enzyme system.

Animals↗
PubMed1996

Correlations between subjective compliance, objective compliance, and factors determining compliance in geriatric hypertensive patients treated with triamterene and hydrochlorothiazide.

There are correlations between objective and subjective compliances on the one hand and factors determining compliance (3 times drug intake per day, no support by the family to get over the disease and no nicotine abuse). In agreement with the literature, mainly subjective criteria (due to disease, therapy, doctor, and environment) influence compliance strongly. To realize their personal psychological task to help the patients even better it is of importance for the doctors to analyze the variability of these parameters. Measures to improve compliance, such as better psychological guidance for the patient taking these factors and the patient's personality into consideration, can be helpful to improve the relatively poor compliance reported in the literature to be as little as 20-50%.

Age Factors↗
PubMed1996

A fixed-dose combination of low molecular weight heparin with dihydroergotamine versus adjusted-dose unfractionated heparin in the prevention of deep-vein thrombosis after total hip replacement.

The low dose heparin regimen (LDH) is not appropriate for prevention of intra- and postoperative thromboembolic complications in high risk patients, especially those undergoing elective hip replacement. Despite LDH prophylaxis, the incidence of deep-vein thrombosis (DVT) remains in a range of 20 to 35%. Adjusted-dose unfractionated heparin prophylaxis is thought to be one of the most effective regimens for thrombosis prophylaxis in this indication, but it requires two or three daily injections as well as precise monitoring of the activated partial thromboplastin time (aPTT). As an attractive alternative, we investigated the efficacy and safety of the low molecular weight heparin (LMWH) certoparin combined with dihydroergotamine (DHE) given once daily. In a randomised, open clinical trial, a total number of 305 patients undergoing total elective hip replacement were enrolled and divided into two groups, either receiving a fixed-dose combination of LMWH (3,000 IU) and DHE (0.5 mg) subcutaneously once daily, or adjusted-dose unfractionated heparin (UFH) subcutaneously every 8 h. The UFH dosage was adjusted daily to keep an aPTT of about 50 s. The aPTT was determined 3 h after the morning injection. During the study, the starting dose (15,000 IU/day) was increased to a plateau value of 28,800 +/- 7,150 IU/day (mean +/- SD) to maintain the aPTT in the prescribed range. The plateau value was achieved after 8 postoperative days. For analysis of efficacy 289 patients were evaluable. The occurrence of deep vein thrombosis was determined by bilateral ascending venography, which was performed on the same day in patients with clinical signs suggesting DVT; and in all remaining patients at the end of the prophylaxis period. Deep vein thrombosis was diagnosed in 17 of 142 patients (12.0%) treated with LMWH/DHE and in 13 of 147 patients (8.8%) treated with adjusted-dose UFH. Combined distalproximal thrombosis was more frequently in patients receiving UFH (n = 5; 3.4%) compared to the LMWH/DHE group (n = 2; 1.4%). These differences are statistically not significant. In the UFH group one case of non-fatal pulmonary embolism occurred. Both prophylaxis regimens were well tolerated; wound bleeding was observed in 8 (5.3%) patients in the LMWH group and in 6 (4.0%) patients in the UFH group. Intraoperative blood-loss volume (mean +/- SD) was 751 +/- 339 mL (LMWH/DHE) and 736 +/- 380 mL (UFH), whereas postoperative drain-loss volume (mean +/- SD) was found to be 523 +/- 333 mL (LMWH/DHE) and 581 +/- 404 mL (UFH). Whole blood transfusion volumes (mean +/- SD) were 570 +/- 202 mL (LMWH/DHE) and 748 +/- 455 mL (UFH). Additionally, red cell replacement volumes (mean +/- SD) were 804 +/- 435 mL (LMWH/DHE) and 720 +/- 328 mL (UHF). Revision of wound or additional drainage were necessary in 3 LMWH/DHE and 7 UFH patients. One patient needed reoperation due to bleeding, 3 (2.0%) had petechia and 1 exhibited an allergic exanthema, all of them in the UFH group. A slight erythema at the injection site was observed in 6 (3.9%) patients receiving LMWH/DHE. During the course of prophylaxis, injection hematomas were documented in 57.9% (LMWH/DHE) and in 61.4% (UFH) of the patients. All differences were statistically not significant. Single daily subcutaneous injections of LMWH/DHE appeared to be safe and efficacious compared to adjusted-dose UFH for prophylaxis of DVT in high-risk patients.

Aged↗
PubMed1996

Molecular analysis of a GM2-activator deficiency in two patients with GM2-gangliosidosis AB variant.

Lysosomal degradation of ganglioside GM2 by beta-hexosaminidase A (hex A) requires the presence of the GM2 activator protein (GM2AP) as an essential cofactor. A deficiency of the GM2 activator causes the AB variant of GM2 gangliosidosis, a recessively inherited disorder characterized by excessive neuronal accumulation of GM2 and related glycolipids. Two novel mutations in the GM2 activator gene (GM2A) have been identified by the reverse-transcriptase-PCR method--a three-base deletion, AAG262-264, resulting in a deletion of Lys88, and a single-base deletion, A410, that causes a frameshift. The latter results in substitution of 33 amino acids and the loss of another 24 amino acid residues. Both patients are homoallelic for their respective mutations inherited from their parents, who are heteroallelic at the GM2A locus. Although the cultured fibroblasts of both patients produce normal levels of activator mRNA, they lack a lysosomal form of GM2AP. Pulse/chase labeling of cultured fibroblasts of the patients, in presence and absence of brefeldin A, indicates a premature degradation of both--mutant and truncated--GM2APs in the endoplasmic reticulum or Golgi. These results were supported by in vitro translation experiments and expression of the mutated proteins. When the mutated GM2APs were expressed in Escherichia coli, both mature GM2AP forms turned proved to exhibit only residual activities in an in vitro assay.

Adult↗
PubMed1996

Epidemiological data on drug use during pregnancy in Thuringia, East Germany, 1993.

An international collaborative WHO-study on drug use in pregnancy of 1987 involving 300 puerperae from Thuringia, East Germany (the former GDR), has partly shown great differences in drug use habits between the countries which had participated on the study. In 1993--after the radical change on the socioeconomic situation in East Germany by the reunification of Germany leading also to changes in health service--an update of the East German data was carried out by repeating the investigation in the same Thuringian region as in 1987. Whereas drug therapy of chronic diseases in pregnancy and drug administration under delivery were widely similar in both investigations, we found a marked increase in drug use in case of illness in the course of pregnancy before admission to hospital for delivery but also in the treatment of nursing women. The differences can be partly put down to socioeconomic development. Because of the continuously enlarging drug market on the one hand and a small data basis on drug risks and side-effects for unborn life on the other hand, a large screening on drug exposition in pregnancy including recording of newborns' data ought to be performed.

Adult↗
PubMed1996

Lack of pharmacokinetic interaction between dextromethorphan, coumarin and mephenytoin in man after simultaneous administration.

The possible interference of simultaneously given dextromethorphan (10 mg dextromethorphan-HBr-H2O), coumarin (10 mg), and mephenytoin (100 mg (R/S)-mephenytoin) on oxidative routes of drug metabolism performed by different cytochrome P450 enzymes and the possibility to detect all of the three substances and their metabolites in urine were investigated in 12 healthy subjects. The concentrations of parent drugs and main metabolites were measured in urine using modified HPLC-methods. All subjects were extensive metabolizers of mephenytoin and dextromethorphan as calculated using hydroxylation index (HI) for mephenytoin and as seen in the quantification of urinary dextromethorphan/dextrophan. A combined determination of coumarin and dextromethorphan with their metabolites or of coumarin and mephenytoin with their metabolites in urine is possible. The combined HPLC separation of all parent compounds and metabolites, however, is not useful because of the necessity to treat the urine samples in very different ways. An overlapping of retention times of the substances in HPLC does not occur. With it a simultaneous administration of all three drugs is possible. A following collection of urine over a period of 8-12 h serves for characterizing activities of different cytochrome P450 enzymes of patients. So particularly the influence of a long term drug therapy on the hydroxylation activities of these cytochromes is easily definable without the disturbing influence of intraindividual variation of drug oxidation with time.

Administration, Oral↗
PubMed1996

[Comparison of serum concentrations of caffeine, 4-methylaminoantipyrine, sulfamethazine and debrisoquin following oral administration of these substances as a cocktail in type II diabetics before and after insulin therapy].

A cocktail of 4 substances (caffeine/CYP1A/CYP1A2, metamizol/CYP2B, debrisoquin/CYP2D6 and sulfamethazine/N-acetyltransferase) was administered to 15 maturity-onset diabetics before and 6 months after insulin therapy (IT) to examine changes in hepatic biotransformation capacity in humans under pathological conditions. Blood and urine samples were taken 6 h after oral administration of the drugs. There were no differences in acetylation- and hydroxylationsphenotyping before or during IT. However, a significant increase in concentration of free sulfamethazine during IT can be interpreted as induction of N-acetyltransferase by poor metabolic control. Comparison of caffeine-concentration showed no significant differences. Obviously in humans CYP1A2 is not influenced by type-II-diabetes mellitus. Concentration of 4-methyl-antityprine (4-MAA), a metabolite of metamizol, was significantly increased during IT. This results shows a possible induction of CYP2B by poor metabolic control.

Adult↗
PubMed1996

Heart rate and temperature in the snail Megalobulimus sanctipauli: role of the cardiac nerve.

The effects of five levels of temperature (15, 20, 25, 30, and 35 degrees C) on the heart rate of Megalobulimus sanctipauli were determined in a group of intact snails (n = 8). The results indicate that heart rate increased almost linearly with temperature over the tested range. The average Q10 calculated for the 15 to 25 degrees C range (1.9) did not differ from that calculated for the 25 to 35 degrees C range (1.7). To investigate the role of the cardiac nerve in mediating these heart rate alterations two others groups were tested: denervated animals (n = 8) and sham-operated control animals (n = 8). The results showed that the relationship between heart rate and each temperature level was not altered by cutting the visceral nerve that innervates the heart, indicating that the nervous system is not implicated in the increase in heart rate induced by increasing temperature. These changes in heart rate are probably due to a direct action of temperature on heart muscle by accelerating the myogenic self-excitation process.

Animals↗
PubMed1995

Construction of stable BHK-21 cells coexpressing human secretory glycoproteins and human Gal(beta 1-4)GlcNAc-R alpha 2,6-sialyltransferase alpha 2,6-linked NeuAc is preferentially attached to the Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-3)-branch of diantennary oligosaccharides from secreted recombinant beta-trace protein.

The human beta-trace protein has been cloned and has been expressed for the first time in a mammalian host cell line. Stable BHK-21 cell lines exhibiting altered terminal sialylation properties were constructed by cotransfection of cells with the plasmids pMT-beta TP or pAB3-1 which contain the cDNAs encoding the human secretory glycoproteins beta-trace protein or antithrombin III and pABSial containing the human Golgi enzyme CMP-NeuAc:Gal(beta 1-4)GlcNAc-R alpha 2,6-sialyltransferase (ST6N) gene. The beta-trace protein was purified by immunoaffinity chromatography and N-linked oligosaccharides were subjected to carbohydrate structural analysis. The enzymically liberated oligosaccharides were found to consist of 90% of diantennary chains as is the case for natural beta-trace protein from human cerebrospinal fluid. About 90% of the total oligosaccharides were recovered in the monosialo and disialo fractions in a ratio of 1:5. The monosialylated oligosaccharides of beta-trace protein coexpressed with human ST6N were found to contain NeuAc in alpha 2,6- or alpha 2,3-linkage in the same ratio. From 1H-NMR analysis as well as calculations of peak areas obtained by HPLC, 60% of the molecules of the disialo fraction were found to contain NeuAc in both alpha 2,3- and alpha 2,6-linkage to Gal beta(1-4)GlcNAc-R, whereas 40% of the molecules of this fraction contained NeuAc in only alpha 2,3-linkage to Gal(beta 1-4)GlcNAc-R. The alpha 2,6-linked NeuAc was shown to be attached preferentially to the Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-3) branch of the diantennary structure. Therefore the in vivo specificity of the newly introduced recombinant human ST6N observed in this study supports the previously reported in vitro branch specificity of the bovine colostrum ST6N activity. Furthermore, these studies demonstrate the suitability of genetically engineered mammalian host cell lines with novel glycosylation properties for the production of human-type glycosylated secretory recombinant polypeptides.

Animals↗
PubMed1995

'Brain-type' N-glycosylation of asialo-transferrin from human cerebrospinal fluid.

Asialo-transferrin from human cerebrospinal fluid was purified to homogeneity. Investigation of the structural characteristics of its oligosaccharides support our hypothesis of 'brain-type' glycosylation of intrathecally synthesized cerebrospinal fluid proteins. For carbohydrate structural analysis, high-pH anion-exchange chromatography, methylation analysis, liquid secondary ion- and matrix-assisted laser desorption/ ionization mass spectrometry of the permethylated derivatives were used. The major structure turned out to be a complex-type agalactodiantennary oligosaccharide with bisecting N-acetylglucosamine and proximal fucose. Analysis of a second transferrin preparation containing both asialo- and sialo-transferrin revealed another major glycan species derived from the sialylated transferrin variant which is galactosylated and lacks bisecting N-acetylglucosamine and fucose.

Amino Acid Sequence↗
PubMed1995

Temporal modulation of antinociception by reciprocal connections between the dorsomedial medulla and parabrachial region.

Microinjection of carbachol into the dorsal parabrachial regio (PBRd) of guinea pigs induces analgesia from the 5th to the 15th min postinjection, as evaluated by the reduction of the vocalization in response to an electric shock applied to one paw. When reversible blockade of the dorsomedial medulla or specifically of the nucleus tractus solitarius (NTS) is performed with xylocaine 5 min after microinjection of carbachol into the PBRd, the analgesic effect continues up to the 45th and to the 60th min, respectively. Blockade of the dorsomedial medulla is achieved by topical application of xylocaine to the area postrema (AP) or microinjection of the drug into the NTS. A prolongation of the duration of the analgesic effect also occurs after the inverse procedure, i.e., after reversible blockade of the PBRd 5 min after topical application of carbachol (1 microgram/microliter)to the AP or microinjection of carbachol into the NTS. In this case, the analgesic action, which lasted up to 30 min when carbachol was applied to the AP and 60 min when microinjected into the NTS, was prolonged up to 60 min and to 80 min, respectively, after reversible blockade of PBR. The present data suggest that the reciprocal connections between the different regions of the dorsomedial medulla and the PBR play an important role in the modulation of the duration of the analgesic effect, and that this fact may be of adaptive importance in the defensive analgesia that occurs in the confrontation between prey and predator.

Analgesics↗