Biomedical subjects

S Marcus

Publications and source records attributed to S Marcus.

At least 73 records · Page 4Linked to original sources

PubMed1994

Complexes between STE5 and components of the pheromone-responsive mitogen-activated protein kinase module.

We present genetic evidence for complex formation of STE5 and the STE11, STE7, and FUS3 protein kinases, the pheromone-responsive mitogen-activated protein kinase module of Saccharomyces cerevisiae. Interaction between STE5 and STE11 is not dependent on STE7, and interaction between STE5 and STE7 does not require STE11. The N-terminal regulatory domain of STE11 is both necessary and sufficient for interaction with STE5. Interaction between STE7 and STE11 is bridged by STE5, suggesting the formation of a multiprotein complex. We also demonstrate biochemical interaction between STE5 and STE11 by using a combination of bacterially expressed fusion proteins and extracts prepared from yeast. Our results suggest that STE5 is a scaffolding protein that facilitates interactions between components of the pheromone-responsive mitogen-activated protein kinase module. We further propose that such scaffolding proteins serve to inhibit cross-talk between functionally unrelated mitogen-activated protein kinase modules within the same cell.

Adaptor Proteins, Signal Transducing↗

PubMed1994

Norfloxacin nicotinate in the treatment of Pseudomonas aeruginosa infection in the genital tract of a bull.

Consecutively collected semen samples from a breeding bull were found to be contaminated with Pseudomonas aeruginosa. Palpation through the bull's scrotum revealed inflammatory changes suggestive of chronic orchiepididymitis in one testicle. For 10 months, all the bull's 13 ejaculates were discarded because the post-thaw viability was < 20%. Norfloxacin nicotinate was injected intramuscularly into the bull at 5 mg/kg daily for 7 days. Serum and semen samples were collected at 24-h intervals during the course of treatment and afterwards and were assayed for NFN concentrations. Drug concentrations in the semen, by microbiological assay, during treatment and up to 120 h after the last treatment ranged from 2.6 to 5.1 micrograms/ml, 14.2 to 43.2 times the corresponding serum drug levels. P. aeruginosa was not isolated from the semen 4 or 15 days after the last injection but was re-isolated after 32 and 64 days. A second similar course of NFN was administered and P. aeruginosa was not isolated from semen samples collected on four occasions, 6, 22, 44 and 94 days after the last treatment.

Animals↗

PubMed1994

Lincomycin and spectinomycin in the treatment of breeding rams with semen contaminated with ureaplasmas.

Ureaplasma species were isolated from semen samples collected sequentially from one Awassi and three Assaf breeding rams. Each ram was injected subcutaneously with an aqueous solution of lincomycin and spectinomycin for five consecutive days at a dose equivalent to 4.5 mg kg-1 lincomycin and 9.0 mg kg-1 spectinomycin daily. Serum and semen samples were collected at intervals during the treatment and assayed for lincomycin. No Ureaplasma species were isolated from semen samples collected during the course of the treatment and at intervals for 17 days after the last treatment. The concentration of lincomycin in semen ranged from 0.51 microgram ml-1 four hours after treatment to 0.08 microgram ml-1 24 hours after treatment, and these levels were three to nine times higher than the corresponding serum concentrations.

Animals↗

PubMed1994

Parotid function and composition of parotid saliva among elderly edentulous African-American diabetics.

This study examined parotid salivary flow rate and composition in three groups of differently treated diabetics and a control group of non-diabetics. The study population was composed of edentulous African-Americans at least 65 years of age. Group A was the control, Group B insulin-dependent (Regular Iletin, U-100 qd.), Group C controlled by oral medication (Tolbutamide, 500 mg qd.), and Group D was diet controlled. All diabetic patients had serum glucose values under 250 mg/dl. Salivary flow rates, secretory IgA, electrolytes (Na+, Cl-, K+, Ca++) and total protein concentrations were evaluated. The results showed no significant differences between groups with respect to salivary flow rates, electrolytes and IgA concentrations. Additionally, all diabetic groups demonstrated a significantly lower salivary total protein concentration when compared to the controls. There appears to be no evident decrease in salivary flow rate in these three differently controlled diabetic groups compared with healthy non-diabetics.

Aged↗

PubMed1994

Concerted action of RAS and G proteins in the sexual response pathways of Schizosaccharomyces pombe.

We have shown that the expression of mam2, the gene encoding the Schizosaccharomyces pombe P-factor pheromone receptor, is dependent upon components of the pheromone signal transduction pathway, including Ras1, Gpa1, Byr1 and Byr2, each of which is required for both conjugation and sporulation. Studies of the expression of mam2 in mutant S. pombe cells confirm previous conclusions, based on the ability of cells to sporulate, that the Byr1 protein kinase acts downstream of the Byr2 protein kinase and that both act downstream of Ras1, the S. pombe RAS homolog, and Gpa1, the G alpha component that mediates the occupancy of the mam2 receptor. In addition, our present studies show that Ras1 and Gpa1 each act downstream from the other and hence act in concert. The Spk1 kinase, which is required for conjugation and sporulation and which is a structural and functional homolog of the vertebrate MAP kinases, is not required for mam2 expression.

Base Sequence↗

PubMed1994

Localization of cyclooxygenase and production of prostaglandins in bovine spermatozoa.

Ejaculated bovine spermatozoa were examined for their capacity to synthesize prostaglandins E2 and F2 alpha (PGE2, PGF2 alpha). It was found that in the absence of exogenous substrate, arachidonic acid, basal PGF2 alpha production was less than that of PGE2. However, addition of 61 mumol arachidonic acid I-1 resulted in at least a twofold increase in PGE2 and PGF2 alpha above control values (1.3 ng and 0.3 ng per 10(8) spermatozoa, respectively). Addition of calcium and the calcium ionophore A23187 to the incubation medium did not cause a significant increase in the production of either PG. The presence of indomethacin (100-200 micrograms ml-1) caused a 50-70% inhibition of the production of both PGs. Activity of cyclooxygenase was determined by western blot analysis, using a specific polyclonal antiserum, and by fluorescence immunohistochemistry using a monoclonal antibody. The western blot displayed a clear signal for the presence of cyclooxygenase in ejaculated and epididymal spermatozoa. The immunohistochemical studies showed that the enzyme is localized in the apical region of the head, the post-acrosomal region and the mid-piece of the tail. Since the synthesis of PGs in the absence of exogenous arachidonic acid is low, the effect of melittin, a known phospholipase A2 activator, on PG production was examined. Incubation of spermatozoa with melittin produced a threefold increase in PGE2 and a sixfold increase in PGF2 alpha. Staurosporine, a protein kinase C inhibitor, inhibited the effect of melittin indicating that activation of phospholipase A2 by protein kinase C is an obligatory step in PG synthesis by bovine spermatozoa.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Bovine besnoitiosis: transfer of colostral antibodies with observations possibly relating to natural transmission of the infection.

Colostral antibodies to B. besnoiti were detected by immunofluorescence in four calves born to two Besnoitia-infected dams, with titres ranging from 1:64 to 1:1024. A specific antibody titre of 1:1024 was found in colostrum collected from one of the dams. Two of the newborn calves, when sampled immediately after birth, were serologically negative to B. besnoiti, but became positive on the next day. In all the calves, antibodies were detectable up to the age of 4 months. Observations concerning passive transfer of antibodies from Besnoitia-infected dams to offspring, and transmission of the infection among infected and non-infected closely kept cows, are discussed.

Animals↗

PubMed1993

Complex formation between RAS and RAF and other protein kinases.

We used a Saccharomyces cerevisiae genetic system to detect the physical interaction of RAS and RAF oncoproteins. We also observed interaction between RAS and byr2, a protein kinase implicated as a mediator of the Schizosaccharomyces pombe ras1 protein. Interaction with RAS required only the N-terminal domains of RAF or byr2 and was disrupted by mutations in either the guanine nucleotide-binding or effector-loop domains of RAS. We observed interaction between MEK (a kinase that phosphorylates mitogen-activated protein kinases) and the catalytic domain of RAF. RAS and MEK also interacted but only when RAF was overexpressed.

Base Sequence↗

PubMed1993

Effect of rest interval on tumor and normal tissue response--a report of phase III study of accelerated split course palliative radiation for advanced pelvic malignancies (RTOG-8502)

From August 1985 through September 1989, 284 patients with advanced pelvic malignancies were entered into a trial (RTOG 8502) of palliative split course radiation (4440 cGy in three courses of 1480 cGy/2 days/4 fractions with a rest of 2-4 weeks between courses). The initial 148 patients were part of a Phase II acceptable response rate and minimal acute or late toxicity (IJRBP 17:659-662, 1989). The present analysis is a report of the subsequent 136 patients randomized between rest intervals of 2 weeks versus 4 weeks to determine if length of rest would influence tumor response or patient toxicity. The patients were stratified for performance status (Karnofsky Performance Status) and histology. The patients were evenly matched for age and sex. There was a trend toward increased acute toxicity incidence in patients with shorter rest interval (5/68 versus 0/68; p = .07). Late toxicity was not significantly different between the two groups. Decreasing the interval between courses did not result in a significant improvement in tumor response (CR+PR = 34% vs. 26%, p = n.s.). More patients in the 2 week groups completed all three courses (72% vs. 63%). Not surprisingly, patients completing cell three courses had a significantly higher overall response rate than for patients completing less than three courses (42% vs. 5%) and higher complete response rate (17% vs. 1%). A multivariate analysis indicated performance status as the significant predictor for number of courses completed. For Karnofsky Performance Status greater than or equal to 80, the survival at 12 months was 40% for the 2 week interval and 25% for the 4 week interval. Performance status and histology were the only significant variables in a multivariate analysis of survival.

Adolescent↗

PubMed1993

RAS function and protein kinase cascades.

This paper reviews recent progress in understanding the function of RAS in three systems: the budding yeast (Saccharomyces cerevisiae), the fission yeast (Schizosaccharomyces pombe) and Xenopus laevis oocytes. One of the functions of RAS in S. cerevisiae is the stimulation of adenylate cyclase. This leads to the activation of the cAMP-dependent protein kinases--a function that has probably not been conserved in evolution. The immediate function of RAS in S. pombe is not known, but it may lead to the activation of a protein kinase cascade. This cascade has likely been conserved in evolution and linkage between it and RAS can be demonstrated in cell-free extracts from Xenopus oocytes. The Xenopus cell-free system provides a means to test specific hypotheses about RAS function and to isolate targets of RAS.

Adenylyl Cyclases↗

PubMed1993

Molecular analysis of the mutations in five unrelated patients with the Lesch Nyhan syndrome.

We have identified the mutations in the hypoxanthine phosphoribosyltransferase (hprt) gene in five patients with the Lesch Nyhan syndrome (LN) by direct sequencing of hprt cDNA and genomic DNA. Three of the mutations affect splicing of exons 1, 2, and 9, respectively, while two are missense mutations in exons 3 and 8. All 5 mutations result in profound hprt deficiency as measured in fibroblast lysates. However, small differences in the clinical phenotype are seen between the patients. All these mutations are unique and have not been reported previously.

Adolescent↗

PubMed1993

Duplication in the hypoxanthine phosphoribosyl-transferase gene caused by Alu-Alu recombination in a patient with Lesch Nyhan syndrome.

We have determined the structure, at the nucleotide sequence level, of a duplication in the hprt gene in a patient with Lesch-Nyhan syndrome (LN). The duplication extends over exons 7 and 8 and approximately 1.8 kb of the surrounding hprt sequence. The duplication junction is localized within two Alu sequences and has apparently been generated by unequal homologous recombination. This is the second reported case of a partial duplication of the hprt gene in an LN patient, and the first that involves an Alu-Alu recombination.

Base Sequence↗

PubMed1993

Prostaglandin production by the oocyte cumulus complex around the time of fertilization and the effect of prostaglandin E on the development of the early bovine embryo.

The oocyte-cumulus complex (25 oocytes per 250 microL medium) produced prostaglandin-F2 alpha (PGF2 alpha) and PGE2 during maturation, immediately following fertilization and for at least 48 h after fertilization. The data suggest that PG production is important in the development of the oocyte; addition of PGE2 (5 ng mL-1) to the fertilization medium increased the rate of cleavage and groups of oocytes with low cleavage rates produced far less PG than groups with high cleavage rates. Measurement of PG in the maturation medium could therefore be a means of assessing the suitability of oocytes for fertilization.

Animals↗

PubMed1993

Functional homology of protein kinases required for sexual differentiation in Schizosaccharomyces pombe and Saccharomyces cerevisiae suggests a conserved signal transduction module in eukaryotic organisms.

We present genetic evidence that three presumptive protein kinases of Schizosaccharomyces pombe, byr2, byr1, and spk1 that are structurally related to protein kinases of Saccharomyces cerevisiae, STE11, STE7, and FUS3, respectively, are also functionally related. In some cases, introduction of the heterologous protein kinase into a mutant was sufficient for complementation. In other cases (as in a ste11- mutant of S. cerevisiae), expression of two S. pombe protein kinases (byr2 and byr1) was required to observe complementation, suggesting that byr2 and byr1 act cooperatively. Complementation in S. pombe mutants is observed as restoration of sporulation and conjugation and in S. cerevisiae as restoration of conjugation, pheromone-induced cell cycle arrest, and pheromone-induced transcription of the FUS1 gene. We also show that the S. pombe kinases bear a similar relationship to the mating pheromone receptor apparatus as do their S. cerevisiae counterparts. Our results indicate that pheromone-induced signal transduction employs a conserved set of kinases in these two evolutionarily distant yeasts despite an apparently significant difference in function of the heterotrimeric G proteins. We suggest that the STE11/byr2, STE7/byr1, and FUS3/spk1 kinases comprise a signal transduction module that may be conserved in higher eukaryotes. Consistent with this hypothesis, we show that a mammalian mitogen-activated protein (MAP) kinase, ERK2, can partially replace spk1 function in S. pombe.

Base Sequence↗

PubMed1993

Virological and immunological studies in patients with acute viral hepatitis.

One hundred and seven patients with acute viral hepatitis (AVH) were studied prospectively regarding the viral aetiological agent HAV, HBV and NANB (by exclusion) using radioimmunoassay. Acute HAV infection occurred in 43 patients, and acute HBV infection in 34 patients, while HDS occurred in two patients only. Acute, presumably NANB, infection occurred in 28 patients. Ten out of 28 sera of patients with AHBV infection were positive for smooth muscle antibody by immunofluorescence. Important findings include: (1) presence of delta superinfection in the absence of HBsAg; (2) HBsAg as the only marker in two patients with AHBV infection; (3) concurrent presence of HBsAg and anti-HBsAg in three patients with AHBV infection.

Acute Disease↗

PubMed1993

A missense mutation in the hypoxanthine phosphoribosyltransferase gene in a pediatric patient with hyperuricemia.

We have identified a mutation in the gene coding for the enzyme hypoxanthine phosphoribosyltransferase in a pediatric patient with hyperuricemia and nephrolithiasis. The mutation is a nucleotide substitution causing an amino acid substitution in the hypoxanthine phosphoribosyltransferase protein. In this patient, fibroblasts but not lymphocytes showed resistance to 6-thioguanine, and reduced enzyme activity was detected in lymphocytes. These results are consistent with the intermediary phenotype associated with partial hypoxanthine phosphoribosyltransferase enzyme deficiency. Altogether, six males in this family suffered from hyperuricemic symptoms, and small differences in phenotype were seen.

Adult↗

PubMed1992

Mutation analysis and prenatal diagnosis in a Lesch-Nyhan family showing non-random X-inactivation interfering with carrier detection tests.

A nonsense mutation at the CpG-site in the codon for Arg(169) in the gene for hypoxanthine phosphoribosyltransferase (hprt) was identified by genomic polymerase chain reaction (PCR) and DNA sequencing in cultured fibroblasts from two brothers with Lesch Nyhan's syndrome. The recurrence of mutation at this CpG-site in several unrelated Lesch-Nyhan families suggests that deamination of 5-methylcytosine is a possible mechanism for mutagenesis. The level of hprt-mRNA in the fibroblasts of the patients was similar to that in healthy controls, whereas hprt-enzyme activity was not detectable. The mutation in this family was also identified in five female relatives and prenatally in a male fetus. Unexpectedly, results from hair follicle analyses and fibroblast selection studies in 8-azaguanine and 6-thioguanine medium showed a non-carrier phenotype in three of the female heterozygotes, whereas X-inactivation mosaicism was demonstrated in one heterozygote. A possible explanation for the apparent non-random X-inactivation in this family is the co-existence of the hprt mutation with an undefined X-linked lethal mutation. This observation is of practical relevance for carrier detection in other Lesch-Nyhan families.

Base Sequence↗

PubMed1992

Dexamethasone inhibition of cyclooxygenase expression in bovine term placenta.

Since both prostaglandin (PG) F2 alpha and corticosteroids are elevated in mammals before the onset of parturition, we studied the effect of the synthetic corticosteroid dexamethasone on PGF2 alpha accumulation and cyclooxygenase (prostaglandin synthase, PGS) expression in the bovine fetal placenta. Cultures were prepared from cotyledons at different stages of gestation. The effect of dexamethasone on PGF2 alpha accumulation and PGS expression was determined by radioimmunoassay and [35S]methionine metabolic labeling followed by immunoprecipitation with specific anti-cyclooxygenase antibodies, respectively. Data demonstrate that in fetal placental cells at term, both PGF2 alpha accumulation and cyclooxygenase expression are significantly inhibited after 18 hours of dexamethasone treatment (150 nM). In contrast, neither first nor second trimester cells were sensitive to dexamethasone treatment. Dexamethasone inhibition of PGF2 alpha synthesis in fetal cells at term was abolished in the presence of RNA or protein synthesis inhibitors (actinomycin D or puromycin, 10 micrograms/ml each). Neither progesterone nor 17 beta-estradiol accumulation were affected by dexamethasone treatment at any stage of gestation. Data suggest that corticosteroids play a role in parturition through PGF2 alpha synthesis regulation by fetal placental cells. Since abnormalities during parturition e.g. retained placenta, are common following dexamethasone induction of labor in cows, we postulate that the local inhibition of PGF2 alpha accumulation by cotyledon cells after corticosteroid administration, may be involved in placental retention.

Animals↗