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M Rapp

Publications and source records attributed to M Rapp.

At least 55 records · Page 3Linked to original sources
PubMed1994

The conditions of primary infection define the load of latent viral genome in organs and the risk of recurrent cytomegalovirus disease.

Recurrence of cytomegalovirus (CMV) from latency is a frequent cause of disease in immunocompromised patients. To date, there is no explanation for the diversity in the clinical manifestations. Primary infection can occur perinatally or later in life, and inevitably results in latent infection. Seropositivity for antibodies against CMV is indicative of latent infection, but is insufficient as a predictor for the risk of recurrence. As a model for this important medical problem, we compared the risks of murine CMV recurrence from latency established after neonatal primary infection and after infection at adult age. The risk of CMV recurrence was high only after neonatal infection. The copy number of latent viral genome in tissues was identified as the key parameter that determines the overall and organ-specific risks of recurrence. Latent CMV burden and risk of recurrence were related to the extent of virus multiplication during primary infection. The presence of latent CMV in multiple organs provides the molecular basis for stochastic events of recurrence in single organs or in any combination thereof. These findings are discussed as a concept of multifocal CMV latency and recurrence. It provides a rationale for the diversity in the clinical outcome of CMV disease.

Animals↗
PubMed1994

Physiology, morphology and detailed passive models of guinea-pig cerebellar Purkinje cells.

1. Purkinje cells (PCs) from guinea-pig cerebellar slices were physiologically characterized using intracellular techniques. Extracellular caesium ions were used to linearize the membrane properties of PCs near the resting potential. Under these conditions the average input resistance, RN, was 29 M omega, the average system time constant, tau 0, was 82 ms and the average cable length, LN, was 0.59. 2. Three PCs were fully reconstructed following physiological measurements and staining with horseradish peroxidase. Assuming that each spine has an area of 1 micron 2 and that the spine density over the spiny dendrites is ten spines per micrometre length, the total membrane area of each PC is approximately 150,000 microns 2, of which approximately 100,000 microns 2 is in the spines. 3. Detailed passive cable and compartmental models were built for each of the three reconstructed PCs. Computational methods were devised to incorporate globally the huge number of spines into these models. In all three cells the models predict that the specific membrane resistivity, Rm, of the soma is much lower than the dendritic Rm (approximately 500 and approximately 100,000 omega cm2 respectively). The specific membrane capacitance, Cm, is estimated to be 1.5-2 muF cm-2 and the specific cytoplasm resistivity, Ri, is 250 omega cm. 4. The average cable length of the dendrites according to the model is 0.13 lambda, suggesting that under caesium conditions PCs are electrically very compact. Brief somatic spikes, however, are expected to attenuate 30-fold when spreading passively into the dendritic terminals. A simulated 200 Hz train of fast, 90 mV somatic spikes produced a smooth 12 mV steady depolarization at the dendritic terminals. 5. A transient synaptic conductance increase, with a 1 nS peak at 0.5 ms and a driving force of 60 mV, is expected to produce approximately 20 mV peak depolarization at the spine head membrane. This EPSP then attenuates between 200- and 900-fold into the soma. Approximately 800 randomly distributed and synchronously activated spiny inputs are required to fire the soma. 6. The passive model of the PC predicts a poor resolution of the spatio-temporal pattern of the parallel fibre input. An equally sized, randomly distributed group of approximately 1% of the parallel fibres, activated within a time window of a few milliseconds, would result in approximately the same composite EPSP at the soma.

Animals↗
PubMed1994

Indolocarbazole protein kinase C inhibitors from rebeccamycin.

Structural modifications were carried out on rebeccamycin, an antitumour antibiotic, to obtain analogues. The inhibitory potencies of these analogues against protein kinase C are compared. The method described represents an alternative route to the staurosporine aglycone, a potent protein kinase C inhibitor.

Aminoglycosides↗
PubMed1994

Expression of the murine cytomegalovirus glycoprotein H by recombinant vaccinia virus.

The sequence of the gene encoding glycoprotein H (gH) of murine cytomegalovirus (MCMV) strain Smith was determined and compared with the sequence of the gH of MCMV strain K181. Transcriptional analysis showed that gH is encoded by a large mRNA of 5.0 kb, which is synthesized late in infection. A recombinant vaccinia virus expressing the MCMV gH open reading frame was constructed (Vac-gH). Anti-MCMV serum precipitated a protein of 87K from Vac-gH-infected cells. Reactivity with a monoclonal antibody showed the identity of the MCMV gH with a 87K envelope glycoprotein described previously by Loh and Qualtiere. Immunization of mice with the Vac-gH recombinant gave rise to an anti-gH serum, which neutralized MCMV without complement in vitro.

Amino Acid Sequence↗
PubMed1994

Disposition in rat of a new fluorinated, biocompatible, non-ionic telomeric carrier.

1. The disposition of the new fluorinated, biocompatible, non-ionic telomeric carrier trisacryl conjugate (F-TAC) labelled with 13C and 14C on the amide function has been studied in the rat after p.o. and i.v. administration. 2. After i.v. administration, excretion measurements have shown that radioactivity was eliminated mainly in the urine (69% within 24 h), and that faecal excretion was low (8% within 72 h). After p.o. administration, faecal elimination was significantly increased (30% within 72 h). No radioactivity was eliminated as 14CO2, after either route of administration. 3. After i.v. administration, plasma radioactivity exhibited a biphasic decrease, with t1/2 = 20 min for the first phase and 29.5 h for the second phase. The maximal plasma concentration was obtained 40 min after oral dosing, followed by a monoexponential decrease with t1/2 = 38.1 h. The ratio AUC (p.o.)/AUC (i.v.) as an assessment of bioavailability was 0.22. 4. After both i.v. and p.o. administration, a relatively homogeneous concentration of radioactivity was found in most organs, close or below the plasma concentration, indicating that tissues do not exhibit a high affinity for this molecule. In addition, F-TAC did not cross the blood-brain barrier. 5. Analysis of urine and plasma on DOWEX AG1X2 anionic resin showed that < 20% of the radioactivity was bound to this support. 13C- and 19F-nmr analysis of the non-bound radioactivity identified it to unchanged F-TAC, with bound radioactivity being due to polyanionic telomers arising from the hydrolysis of the amide function.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1994

Enhancement by O6-benzyl-N-acetylguanosine derivatives of chloroethylnitrosourea antitumor action in chloroethylnitrosourea-resistant human malignant melanocytes.

The exposure of cells to O6-methylguanine or O6-benzylguanine is known to reduce the enzymatic activity of O6-alkylguanine-DNA alkyltransferase, which leads to a sensitivity enhancement to chloroethylnitrosourea cytotoxic effects. The main disadvantage of the guanine derivatives is their low water solubility, which makes their formulation difficult for clinical use in humans. To overcome this problem, water-soluble O6-alkylguanine-DNA alkyltransferase inhibitors have been synthesized and their ability to increase the chloroethylnitrosourea potency in vitro and in vivo was evaluated. Four water-soluble molecules (O6-methyl-N-acetylguanosine; O6-methyl-N-acetyldeoxyguanosine; O6-benzyl-N-acetylguanosine, BNAG; and O6-benzyl-N-acetyldeoxyguanosine, BNADG) were tested for sensitivity of M4Beu cells to N'-(2-chloroethyl]-N[2-(methylsulfonyl)ethyl]-N'-nitrosourea (cystemustine) based on the colony-forming ability of M4Beu melanoma cells. The cell sensitivity to cystemustine was increased by benzylated derivative pretreatment but not with methylated derivative pretreatment. Furthermore, BNAG or BNADG pretreatment followed by cystemustine was less cytotoxic than BNAG or BNADG given simultaneously and followed 24 hr later by BNAG or BNADG. Comparative studies performed with O6-benzylguanine on the same model showed that this inhibitor was effective at lower concentrations than the corresponding guanosine or deoxyguanosine analogs. Preliminary pharmacological assays were carried out in nude mice bearing the M4Beu tumor to determine whether the BNAG-cystemustine combination has greater antitumor activity than cystemustine alone. Simultaneous i.p. injection of 200 mg/kg of BNAG and 15 mg/kg of cystemustine followed by an i.p. injection 4 hr later of 200 mg/kg of BNAG led to a significant enhancement of inhibition of tumor growth.

Animals↗
PubMed1993

Evaluation of cefixime in the treatment of bacterial maxillary sinusitis.

The efficacy and safety of cefixime, the first oral third-generation cephalosporin, were evaluated in a multicenter clinical trial involving 118 adult patients with acute sinusitis or acute exacerbations of chronic sinusitis. Patients received a single daily dose of 400 mg of cefixime for a mean duration of 10 days; 106 patients completed a course of therapy. Clinical cure and improvement were achieved in 90% of these patients (61% cured and 29% improved). Among the patients evaluated again 2 weeks after therapy, 91% had a sustained clinical cure or improvement. Sinus exudate specimens were obtained from all patients by transantral puncture before therapy. Pathogens were isolated from 76 patients (66%), the most common pathogens being Haemophilus influenzae, alpha-hemolytic streptococci, and Streptococcus pneumoniae. Eighty-six percent of pathogens were presumed eradicated. Three patients discontinued therapy because of side effects. The most frequently reported adverse effects were gastrointestinal, with 20% of patients reporting diarrhea. Cefixime was effective in the treatment of bacterial sinus infections in adults and was well tolerated.

Acute Disease↗
PubMed1993

Disposition of stiripentol in the pregnant and non-pregnant female rat.

1. The disposition of stiripentol labelled with 14C and 3H on two positions has been studied in the pregnant and non-pregnant female rat after p.o. administration of a 200 mg/kg dose. 2. For both labelled species radioactivity was eliminated mainly in the faeces (69% within 72 h). Urinary excretion was rather low (22% within 72 h). No significant difference was found between the disposition of the two labelled species. 3. For both labelled species concentrations of radioactivity reached a plateau in the plasma and tissues between 1 and 6 h after administration. The liver, fat, mammary gland and adrenal gland were the most extensively-labelled organs. The affinity for the mammary gland was significantly greater in pregnant rats and for the adrenal gland was significantly greater in the non-pregnant rats. The fact that the concentration in the placenta was higher than in the foetus demonstrated that this membrane acts as a barrier for the penetration of the drug in the amniotic fluid. 4. Chromatographic analysis of the faeces and urine showed that an important portion of the dose remained unabsorbed through the gastrointestinal tract. The absorbed fraction undergoes an extensive first-pass metabolism involving mainly the oxidative cleavage of the methylenedioxy ring. Comparison with the results of other work conducted on the non-pregnant rat demonstrated that pregnancy did not affect the disposition and metabolic process.

Adrenal Glands↗
PubMed1993

In vitro uptake of technetium-99m-teboroxime in carcinoma cell lines and normal cells: comparison with technetium-99m-sestamibi and thallium-201.

Since 201Tl, 99mTc-sestamibi and 99mTc-teboroxime concentrate in cardiac cells through different mechanisms, we compared their uptake in cultured normal cells and carcinoma cell lines in order to define their possible use for tumor evaluation in vivo. Four lines of normal cells from animals, including myocytes from newborn rats, and four lines of human carcinoma cell lines were incubated for 1 hr with 37 kBq of either tracer. Results, expressed in percent of the total activity taken up by 1 million cells, showed a 9% difference between the uptake of teboroxime by normal and carcinoma lines (24.6% +/- 2.8% versus 22.5% +/- 2.1%, respectively, p < 0.05). Mean uptake was 80% higher in tumor than in normal cells for 201Tl (5.39% +/- 1.33% versus 3.00% +/- 1.08%, respectively, p < 0.001) and nearly 4 times higher for sestamibi (5.37% +/- 2.34% versus 1.44% +/- 1.88%, p < 0.001). For both agents, uptake by the myocytes and carcinoma cells was comparable (5.14% +/- 0.11% for 201Tl and 5.28% +/- 1.03% for sestamibi). When the myocytes are excluded from the group of normal cells, the uptake is 112% higher in tumor than in normal cells for 201Tl (5.39% +/- 1.33% versus 2.54% +/- 0.44%, p < 0.001) but it becomes nearly nine times higher for sestamibi (5.37% +/- 2.34% versus 0.60% +/- 0.23%, p < 0.001). It is concluded that these experiments show that the uptake of sestamibi was the most discriminant to separate between normal and malignant cells, while teboroxime was the less discriminant. Potential clinical applications for tumor visualization based on differences in sestamibi and teboroxime uptake could be envisioned.

Animals↗
PubMed1992

Fluoxetine shortens circadian period for wheel running activity in mice.

Fluoxetine is a potent and specific serotonin re-uptake inhibitor and an effective antidepressant drug. Male mice were treated with either fluoxetine (8 mg/kg body weight per day) or saline. Wheel running activity was monitored for 2 weeks in a 12:12 LD cycle followed by 2 weeks in constant darkness (DD). Fluoxetine significantly shortened free-running circadian period for wheel running activity (23.93 +/- 0.08 h for fluoxetine treated mice versus 24.17 +/- 0.07 h for saline treated mice; p less than 0.03). These results are consistent with a role for serotonin in the regulation of circadian period in mice.

Animals↗
PubMed1992

Synthesis of potential 99mTc nitrido tumor imaging disposition in mice.

Several cationic or neutral technetium-nitrido complexes of Schiff bases [for which 5-methyl 3-(2-hydroxyphenyl methylene) dithiocarbazate (L1) was a prototype], bis-aminoethanethiol (BAT-TM) and macrocyclic amines were prepared. We report here, the synthesis and isolation of these TcNLn complexes from reaction mixtures by high pressure liquid chromatography or sephadex G25 column. In vivo tissue distribution studies were performed on tumor bearing mice (B16, EMT6, 3LL) after i.v. injection of 10-20 microCi of TcNLn. Although pharmacokinetic differences appeared between the three studied ranges, we did not obtain proof of any particular specificity to tumor tissues. Nevertheless, the complexes were very stable and some of the ligands could be used as chelators after linking side chains or groups inducing specific tumor localization.

Animals↗
PubMed1992

Identification of the murine cytomegalovirus glycoprotein B gene and its expression by recombinant vaccinia virus.

The gene encoding glycoprotein B (gB) of murine cytomegalovirus (MCMV) strain Smith was identified, sequenced, and expressed by recombinant vaccinia virus. The gB gene was found adjacent to the polymerase gene, as it is in the genome of human cytomegalovirus (HCMV). The open reading frame consists of 2,784 nucleotides capable of encoding a protein of 928 amino acids. Comparison with gB homologs of other herpesviruses revealed a high degree of homology. The similarity between the MCMV gB and the HCMV gB is most prominent, since 45% of the amino acids are identical. In addition, all cysteine residues are at homologous positions, indicating a similar tertiary structure of the two proteins. In contrast to HCMV, the MCMV gB mRNA is a true late transcript. A recombinant vaccinia virus expressing the MCMV gB gene has been constructed (Vac-gB). Antibodies raised against the Vac-gB recombinant precipitated proteins of 130, 105, and 52 kDa from MCMV-infected cells. The identity of the MCMV gB with the major envelope glycoprotein of MCMV described by Loh et al. was shown (L. C. Loh, N. Balachandran, and L. F. Qualtiere, Virology 166:206-216, 1988). Immunization of mice with the Vac-gB recombinant gave rise to neutralizing antibodies.

Amino Acid Sequence↗
PubMed1992

Evidence for the presence of endogenous 19-nortestosterone in the cow peripartum and in the neonatal calf.

Urine samples were collected from five Brown Swiss cows during the 18 days prior to and 11 days after parturition and were analysed for 19-nortestosterone using an enzyme immunoassay. Nortestosterone concentrations ranged from 70 to 130 nmol/l in all samples taken before parturition. The levels declined within two days, and 11 days post partum no nortestosterone was detectable. In urine from newborn calves, maximal nortestosterone concentrations were determined during the first day of life (10.9-120 nmol/l), declining below 7.3 nmol/l until day 3 in most animals and remaining below the detection limit (less than 3.6 nmol/l) after day 8 in all animals. There was no obvious difference between cows carrying a male or a female calf nor between newborn male or female calves. Using the combined methods high performance liquid chromatography/enzyme immunoassay and high performance liquid chromatography/gas chromatography-mass spectrometry, the immunoreactivity in urine was identified to be 19-nortestosterone-17 alpha. Although there is unequivocal evidence for the endogenous production of nortestosterone in pregnant cows, its function for placenta physiology, pregnancy anabolism and parturition remains unclear. However, new threshold levels for residue control of nortestosterone need to be fixed in accordance with the endocrine status of the animals.

Animals↗
PubMed1990

DNA damage induced by a new 2-chloroethyl nitrosourea on malignant melanoma cells.

Different biological aspects of a novel 2-chloroethyl nitrosourea derived from cysteamine, N'-(2-chloroethyl)-N-[2-(methylsulfinyl)ethyl]-N'- nitrosourea (CMSOEN2), were studied. Drug-induced cytotoxic effects, uptake kinetics, DNA damage, and O6-alkylguanine-DNA alkyltransferase activity were determined in 3 melanoma cell lines: the murine B16 and 2 human metastatic-derived cell lines (M4 Beu and M3 Dau). We found that radioactivity uptake and incorporation in acido-precipitable material was inversely proportional to cell drug viability. The highly CMSOEN2-sensitive B16 line showed the lowest total radioactivity uptake. In fact, among the melanoma cell parameters studied, 3 of them were well correlated: (a) cytotoxicity as reflected by the colony-forming assay; (b) DNA cross-link frequency estimated by the alkaline elution technique; and (c) O6-alkylguanine-DNA alkyltransferase activity (Mer phenotype), defined as the ability of cell extracts to remove O6-methylguanine from N-methyl-N-nitrosourea-alkylated DNA. The 2 human cell lines (M4 Beu and M3 Dau), the most resistant to the cytostatic drug effects, showed little or no ability to form DNA lethal cross-links. These results correspond to the higher O6-alkylguanine-DNA alkyltransferase activity found in human-derived cell lines compared with that present in murine B16 cell lines. This study confirms that the cell content in this repair DNA protein is certainly one of the important factors implicated in the variability of response to 2-chloroethyl nitrosourea treatment observed in a number of established malignant cell lines. It has been shown that pretreatment of derived cell lines with methylating agents (N-methyl-N-nitrosourea, N-methyl-N'-nitro-N-nitrosoguanidine) or O6-methylguanine used as a free base, increased cytotoxic effects of this class of anticancer agents, likely by saturating receptor sites (sulfhydryl groups) of this specific DNA repair enzyme. Nevertheless, in preliminary Phase I and II clinical trials, 2 patients who had been treated with multiple chemotherapies including alkylating agents [1-(2-chloroethyl)-3- cyclohexyl-1-nitrosourea, 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide, platinum derivatives], presented complete or partial remission after CMSOEN2 treatment. Our results raise the question of the exact relation between the Mer phenotype determined in derived murine or human cultured cells and that directly observed on surgically excised tumors in cancer patients. The original Mer phenotype could be modified by cell culture conditions since it has been shown that O6-alkylguanine-DNA alkyltransferase activity is widely distributed between normal and tumoral tissues without any real difference.

Antineoplastic Agents↗
PubMed1989

Distinction between oral and parenteral application of 19-nortestosterone by residue analysis in kidney fat from veal calves using high-performance liquid chromatography and enzyme immunoassay.

Kidney fat samples from animals either untreated or after different treatments with 19-nortestosterone (NT) were cleaned up and NT-17 beta and 19-norandrostenedione (NA) were purified using high-performance liquid chromatographic (HPLC) systems that allowed their complete separation from other steroids and interfering physiological compounds. HPLC fractions and urine samples were analysed by an enzyme immunoassay that measures both steroids equally well (antigen: NT-17 beta-hemisuccinate-bovine serum albumin). In samples from untreated animals no NT metabolites were detectable (less than 10 pg/g NT-17 beta and less than 10 pg/g NA in fat; less than 0.25 pg/ml NT-17 beta + NT-17 alpha in urine). After adding NT to animal feed the urine became positive, whereas in the fat no residues were detectable. After different injections of NT both the fat and urine were positive. Only after parenteral application did free steroids enter the circulation and adipose tissues.

Adipose Tissue↗
PubMed1989

Determination of hormone contaminants in milk replacers by high-performance liquid chromatography and immunoassay.

Certain milk replacers were reported to cause 19-nortestosterone (NT)-positive urine samples after feeding them to veal calves. In order to find the possible source of contamination, milk replacers and crude fat and meat meal from homogenized veal calves and commercial crude fat from a rendering plant were analysed for NT plus its metabolites and constituents of illicit 'cocktails' (NT esters, estradiol benzoate and medroxyprogesterone acetate). The steroids were separated using different high-performance liquid chromatographic systems and measured by specific immunoassays. The results show that animal food processed from carcasses of treated animals contains hormone concentrations that may cause positive urine samples in animals fed on such feed.

Anabolic Agents↗