Biomedical subjects

J Blaney

Publications and source records attributed to J Blaney.

7 recordsLinked to original sources

PubMed1998

Modification of a receptor-binding surface of epidermal growth factor (EGF): analogs with enhanced receptor affinity at low pH or at neutrality.

Six mutants of human epidermal growth factor (EGF), which carry single point substitutions within a surface patch proposed to juxtapose the bound receptor, were prepared and characterized for receptor affinity and mitogenicity. Receptor affinities relative to EGF are G12Q > H16D > Y13W > Q43A approximately = H16A approximately = EGF >> L15A. Notably, the reduced receptor affinity of mutant L15A indicates that Leu15 probably contributes substantially to receptor binding whereas unaltered receptor affinities observed for analogs H16A and Q43A indicate that neither His16 nor Gln43 contributes significantly to this interaction. On the other hand, the observed enhanced receptor affinities of analogs G12Q, Y13W and H16D highlight surface loci where additional productive receptor-binding contacts can be introduced. Interestingly, at acidic pH analog H16A reveals substantially greater receptor affinity than that of EGF, a property which may offer enhanced therapeutic utility in acidic environments in vivo.

Amino Acid Sequence↗

PubMed1996

Differential effects of I kappa B molecules on Tat-mediated transactivation of HIV-1 LTR.

The tat gene product of the human immunodeficiency virus type 1 (HIV-1) strongly induces the transcription directed by the viral long terminal repeat (LTR). Tat acts by interacting with a target RNA element located immediately downstream of the initiation site. In addition, the action of Tat appears to be assisted by the upstream DNA enhancer elements, including the binding sites for the NF-kappa B/Rel family of host transcription factors. In the present study, we demonstrate that Tat transactivation of the HIV-1 LTR is markedly inhibited by several cytoplasmic inhibitors of NF-kappa B/Rel, suggesting the critical involvement of these host transcription factors in the function of the viral Tat protein. Furthermore, the various NF-kappa B inhibitors appear to have differential effects on Tat. While I kappa B alpha, I kappa B beta, and p100 potently inhibit Tat-mediated transactivation, p105 fails to inhibit, but even moderately synergizes, the action of Tat. We further demonstrate that the action of these NF-kappa B/Rel inhibitors on Tat correlates with their inhibitory activities on the RelA subunit of NF-kappa B. Finally, we show that a degradation-resistant I kappa B alpha mutant is able to potently inhibit Tat-mediated activation of the HIV-1 LTR in both untreated and tumor necrosis factor alpha-stimulated T cells, thus suggesting that such an I kappa B alpha mutant may serve as a constitutive repressor of HIV-1 LTR.

Cell Line↗

PubMed1996

Screening of the PDE6B gene in patients with autosomal dominant retinitis pigmentosa.

Each of the 22 exons and 140 bp of the 5' untranslated region of the gene encoding the beta-subunit of cGMP-phosphodiesterase (PDE6B) were screened by denaturing gradient gel electrophoresis for mutations in the DNAs of 54 unrelated individuals with autosomal dominant retinitis pigmentosa. Six different sequence variants were found in seven patients. Four of the sequence variants did not segregate with disease in the families of the respective probands and/or were present in control DNAs. The remaining two sequence variants, a Leu228His missense in exon 3 and a G to A transition in the tenth base of the splice acceptor site of intron 8, were both present in the same proband. One or the other of the two sequence variants was present in each affected member of the proband's small family and neither sequence variant was present in the one unaffected member nor in 75 unrelated controls. However, no effect on splicing of mRNA was observed in expression studies of DNA constructs containing the G to A transition. Therefore, mutations in PDE6B could not be shown to be the cause of adRP in this group of patients.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1995

Mutations in the PDE6B gene in autosomal recessive retinitis pigmentosa.

We have studied 24 small families with presumed autosomal recessive inheritance of retinitis pigmentosa by a combination of haplotype analysis and exon screening. Initial analysis of the families was made with a dinucleotide repeat polymorphism adjacent to the gene for rod cGMP-phosphodiesterase (PDE6B). This was followed by denaturing gradient gel electrophoresis (DGGE) and single-strand conformation polymorphism electrophoresis (SSCPE) of the 22 exons and a portion of the 5' untranslated region of the PDE6B gene in the probands of each family in which the PDE6B locus could not be ruled out from segregating with disease. Two probands were found with compound heterozygous mutations: Gly576Asp and His620(1-bp del) mutations were present in one proband, and a Lys706X null mutation and an AG to AT splice acceptor site mutation in intron 2 were present in the other. Only the affecteds of each of the two families carried both corresponding mutations.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1992

Heart rate response of firefighters to actual emergencies. Implications for cardiorespiratory fitness.

Heart rate (HR) and oxygen consumption (VO2) responses during actual fire-suppression emergencies were monitored in 10 male firefighters. These firefighters worked at 157 +/- 8 beats per minute (bpm) for 15 +/- 7 minutes. This was 88 +/- 6% of their previously determined HR max. Based on treadmill testing, the HR x VO2 relationship was established for each firefighter. The predicted VO2 derived from HR monitoring in actual emergencies was 25.6 +/- 8.7 mL.kg-1.min-1 or 63 +/- 14% of VO2 max (40.0 +/- 6.5 mL.kg-1.min-1). These values on the cardiorespiratory response to actual emergencies are very similar to results derived from studies employing fire-suppression simulations. Recommendations for the VO2 max of firefighters ranging from 33.5 to 42.0 mL.kg-1.min-1 that have been generated from simulation testing appear appropriate given the cardiorespiratory responses to actual emergencies.

Adult↗

PubMed1990

Impact of exercise training on plasma adrenocorticotropin response to a well-learned vigilance task.

Plasma adrenocorticotropin hormone (ACTH), cortisol, heart rate, self-reported state anxiety and total reaction time responses in physically active (n = 8) and sedentary (n = 11) middle-aged men were compared during performance of a well-learned, psychologically challenging task. The groups were similar in age (active: 39.9 +/- 8.4 yr vs. sedentary: 44.4 +/- 7.2 yr) and trait anxiety (29.4 +/- 5.2 vs. 34.5 +/- 12.6), but they had different maximal oxygen consumption relative to lean body weight (68.6 +/- 7.1 vs. 44.7 +/- 4.6 ml.kg(-1).min(-1)). During performance of the psychological protocol, the total group had significant increases in heart rate and state anxiety, whereas both ACTH and cortisol remained near baseline levels. ACTH and cortisol were not different between the groups. The sedentary group exercise trained for 4 mo, which resulted in an 18% improvement in maximal aerobic capacity (vO2 max). Exercise intervention did not significantly alter the neuroendocrine response compared to pre-training values or compared to a corresponding control group. These findings suggest that enhanced cardiovascular fitness resulting from exercise training does not affect anterior pituitary-adrenocortical activity during performance of a practiced vigilance task.

Adrenocorticotropic Hormone↗

PubMed1990

Plasma free and sulfoconjugated catecholamines during sustained exercise.

Previous research established a relationship between circulating sulfoconjugated norepinephrine (NE-SO4) and oxygen consumption at various exercise intensities. In this study, the stability of the NE-SO4 response was examined during sustained exercise at a constant relative intensity. Seven trained men bicycled at 78 +/- 3% of their maximal O2 consumption for 28 min and then rested on the ergometer for a comparable duration. After a 30-min rest, plasma samples were collected through an indwelling catheter at 7-min intervals during the exercise and recovery periods. Free NE and epinephrine increased sixfold during exercise. These changes were accompanied by increases in sulfoconjugated catecholamines, but only NE-SO4 achieved statistical significance (rest, 712 +/- 602; exercise, 1,329 +/- 1,163 pg/ml). This occurred at three collection periods (14, 21, and 28 min). Approximately 35, 52, and 95% of NE, epinephrine, and dopamine, respectively, existed as sulfoconjugated during exercise. Subject variation was present in the sulfoconjugated catecholamine response that could not be attributed to corresponding differences in circulating free catecholamine release. These findings implicate blood flow as a factor in the sulfoconjugation of NE, but not epinephrine or dopamine.

Adult↗