PubMed Health⌕ Search

Biomedical subjects

C Murphy

Publications and source records attributed to C Murphy.

At least 145 records · Page 8Linked to original sources
PubMed1993

Snurposomes and coiled bodies.

In the GV of amphibian oocytes, the splicing snRNPs (U1, U2, U4, U5, and U6) occur on most of the lampbrush chromosome loops in association with the nascent transcripts. They also occur in thousands of small extrachromosomal bodies (1-4 microns in diameter) designated B snurposomes. U7 snRNA, which is involved in processing the 3' end of histone pre-mRNAs, occurs in a few dozen extrachromosomal bodies (1-20 microns in diameter) called C snurposomes. C snurposomes often have B snurposomes attached to their surface and B-like inclusions; these compound structures are known as spheres or sphere organelles. One or two sphere organelles are attached to the lampbrush chromosomes at the histone gene loci. Two snRNAs (or snoRNAs) known to be involved in pre-rRNA processing (U3 and U8) occur in the 1000 or so extrachromosomal nucleoli of the GV. We looked for a snurposome that might contain U3 and U8 but not rDNA or rRNA. We were unable to find such a snurposome, but we did identify a hitherto unrecognized population of minute nucleoli in the size range of B snurposomes. Prenucleolar bodies in telophase/early interphase nuclei meet the definition of a pre-rRNA snurposome in that they contain U3 snoRNA and fibrillarin (and probably other processing components) but lack rDNA and do not synthesize rRNA. The structures previously identified as prenucleolar bodies in pronuclei formed in vitro in Xenopus egg extracts share many components with coiled bodies from HeLa nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Reversible inhibition of urea exchange in rat hepatocytes.

Urea exchange is enhanced in renal collecting duct cells and erythrocytes by transporters which can be inhibited by phloretin and urea analogs such as thiourea. In this study, evidence for a comparable transporter was found in rat livers perfused with solutions which contained no red cells and in suspensions of hepatocytes. Bolus injections containing 125I-albumin (intravascular indicator), 99mTc-DTPA (extracellular indicator), 3HOH (water indicator), and [14C]urea were administered into the portal vein and fluid was collected from the hepatic vein. Under control conditions, [14C]urea and 3HOH emerged from the hepatic vein at nearly the same rate. However when the perfusate contained 2.5 mM phloretin (equivalent to 0.058 mM phloretin not bound to albumin), the amount of [14C]urea which had been recovered in the hepatic venous outflow by the time of peak 125I-albumin concentrations exceeded 3HOH recovery by a factor of 2.31 +/- 0.23 (n = 7). When the perfusate contained 200 mM thiourea, the comparable recovery of [14C]urea from the hepatic veins exceeded that of 3HOH by a factor of 3.48 +/- 0.44 (n = 7). These effects were at least partially reversible and suggested inhibition of urea transporters in hepatocytes. This conclusion was supported by studies of unloading of [14C]urea from hepatocytes which were exposed to unlabeled solutions: in the presence of phloretin, the amount of [14C]urea remaining within hepatocytes at 4 s was approximately twice that remaining in hepatocytes which had not been exposed to phloretin. Rapid transport of urea out of hepatocytes may increase urea synthesis and minimize cellular swelling due to urea accumulation.

Animals↗
PubMed1993

The community's tolerance of the mentally ill.

A survey of attitudes to mental illness was conducted in a quota sample of about 2000 subjects in Malvern and Bromsgrove. Factor analysis showed three main components - benevolence, authoritarianism, and fear of the mentally ill. Residents of Bromsgrove, which is served by a traditional mental hospital, were slightly more tolerant than those living in Malvern, which has a community-based service, and has seen the closure of two mental hospitals in its vicinity during the last 10 years. The main demographic determinants of tolerance are age, education, occupation, and acquaintance with the mentally ill.

Adolescent↗
PubMed1993

A comparison of responses to the mentally ill in two communities.

Vignettes representing mentally ill people were presented to about 2000 randomly selected residents in Bromsgrove, served by a mental hospital, and Malvern, served by a community-based psychiatric service. They were asked about the likely cause of the condition, what action they would take, and what agencies were most likely to help. In Malvern, residents seemed more enterprising in involving various agencies and more tolerant. It is possible to derive simple 'action scores' as an indicator of such tolerance. Although there were significant demographic differences between subgroups, overall identification of vignette subjects as mentally ill was surprisingly low, and so was knowledge both of community psychiatric nurses as an agency, and of the location of dispersed treatment facilities in both areas.

Adolescent↗
PubMed1993

The interaction of the tyrosine kinase pp60src with membrane and cytoskeletal components.

To study the mechanism of oncogenic transformation we have investigated the association of pp60v-src with the cytoskeleton using a variety of mutants. Transformation is associated with the interaction of pp60v-src with the cytoskeleton, specifically in adhesion plaques. Biochemical analysis has shown a correlation between tyrosine-specific phosphorylation of the fibronectin receptor and the loss of surface-bound fibronectin, but no such correlation with phosphorylation of vinculin or talin. The role of the nontransforming protooncogene product pp60c-src was studied in platelets, which express large amounts of this protein. In resting platelets pp60c-src was soluble in detergent-containing buffers, however it became associated with the cytoskeleton, but not the membrane skeleton, after platelet activation. This association was inhibited by EDTA or RGDS peptides and was therefore dependent on occupancy of a platelet integrin, gpIIb/IIIa. The role of pp60c-src-associated tyrosine phosphorylation in platelet activation was also investigated. Inhibitors of tyrosine phosphorylation inhibited integrin-dependent platelet aggregation and second messenger production, indicating a close linkage between matrix receptor occupancy, pp60c-src association with the cytoskeleton and platelet function.

Animals↗
PubMed1993

Psychosocial predictors of high-risk sexual behavior among HIV-negative homosexual men.

Despite general awareness that human immunodeficiency virus (HIV) is transmitted sexually, people continue to engage in high-risk behavior. As part of a larger HIV project, the Coping in Health and Illness Project (CHIP), we studied the association of psychosocial factors with sexual risk taking behaviors in 53 HIV-negative gay men residing in a HIV non-epicenter. Risk behavior was measured on a 3-point scale, taking into account condom use, number of sexual partners, and type of sexual activity. Independent variables included mood, coping, history of substance dependence, social support, and acceptance of sexual orientation. Sixty percent of the subjects practiced lower-risk, 17.3% practiced moderate-risk, and 23.1% practiced high-risk behavior. We found that risk behavior was positively correlated with optimism (Life Orientation Test) (OR = 2.7; 95% CI = 1.3-5.5), anger (POMS) (OR = 2.6; 95% CI = 1.2-5.7), and negatively related to emotional control (Courtauld) (OR = 0.5; 95% CI = 0.3-1.0), and gay self-acceptance (OR = 0.35; 95% CI = 0.2-0.8). Further study is needed to determine if sexual risk-taking behavior in HIV-negative gay men will be reduced by enhancing gay self-esteem, increased understanding and adaptive use of anger, and modifying overly optimistic attitudes to increase realism.

Adaptation, Psychological↗
PubMed1992

Sarcolipin, the "proteolipid" of skeletal muscle sarcoplasmic reticulum, is a unique, amphipathic, 31-residue peptide.

The sarcoplasmic reticulum of rabbit skeletal muscle contains a small "proteolipid," i.e., a protein which is soluble in acidic CHCl3/CH3OH. We propose the name sarcolipin for this small protein, to signify its lipid-like solubility and association with the sarcoplasmic reticulum. We have determined the following amino acid sequence for sarcolipin, using protein chemistry methods: M E R S T R E L C L N F T V V L I T V I L I W L L V R S Y Q Y. This 31-residue sequence includes a 19-residue hydrophobic segment which probably spans the sarcoplasmic reticulum membrane. The molecular weight calculated from the sequence, 3733, agrees with that measured by fast atom bombardment mass spectrometry, showing that sarcolipin contains no attached fatty acyl or other prosthetic groups.

Amino Acid Sequence↗
PubMed1992

5S rRNA-encoding genes of the marsupial frog Gastrotheca riobambae.

The major 5S rRNA gene repeat of the marsupial frog, Gastrotheca riobambae, is 1052 bp in length. It contains a 5S rRNA gene similar to the Xenopus laevis somatic gene, two spacer regions, and a pseudogene. The G. riobambae haploid genome contains about 500 copies of this predominant repeat. This relatively low number of 5S rRNA genes is associated with a limited amplification of the 18S, 5.8S and 28S rRNA genes in oocytes and with a slow rate of early development.

Animals↗
PubMed1992

Transcription on lampbrush chromosome loops in the absence of U2 snRNA.

The five small nuclear RNAs (snRNAs) involved in splicing occur on the loops of amphibian lampbrush chromosomes and in hundreds to thousands of extrachromosomal granules called B snurposomes. To assess the role of these snRNAs during transcription and to explore possible relationships between the loops and B snurposomes, we injected single-stranded antisense oligodeoxynucleotides (oligos) against U1 and U2 snRNA into toad and newt oocytes. As shown before, antisense U1 and U2 oligos caused truncation of U1 and complete destruction of U2 snRNAs, respectively. However, injection of any oligo, regardless of sequence, brought on dramatic cytological changes, including shortening of the chromosomes and retraction of the lateral loops, with concomitant shutdown of polymerase II transcription, as well as disappearance of some or all of the B snurposomes. When injected oocytes were incubated for 12 h or longer in physiological saline, these changes were reversible; that is, the chromosomes lengthened, transcription (detected by 3H-UTP incorporation) resumed on newly extended lateral loops, and B snurposomes reappeared. In situ hybridization showed that loops and B snurposomes had negligible amounts of U2 snRNA after recovery from injection of the anti-U2 oligo, whereas these structures had normal levels of U2 snRNA after recovery from a control oligo. Thus, the morphological integrity of B snurposomes and lampbrush chromosome loops is not dependent on the presence of U2 snRNA. Because transcription occurs in the absence of U2 snRNA, we conclude that splicing is not required for transcription on lampbrush chromosome loops.

Animals↗
PubMed1992

Ascending aortic Doppler velocity and the prediction of exercise capacity in post-infarction left ventricular dysfunction.

A system to improve analysis of the aortic pulsed Doppler velocity signal has been developed and used to study cardiac performance during a 4 min, 25 W incremental stage supine bicycle exercise to exhaustion. Twenty-two male subjects with stable chronic ischaemic heart disease were studied (15 with NYHA class II/III heart failure, and seven age-matched class I subjects). None had evidence of reversible ischaemia. Peak velocity (PV) from the intensity weighted mean velocity profile, early acceleration (eA) and stroke distance (SD) were all significantly lower at rest in class II/III compared to class I. For the change from rest to 50 W, PV did not alter, eAC increased significantly (P less than 0.05) and to a similar extent in both groups (18.6% class II/III vs 16.4% class I) and SD was reduced from 7.8 to 5.9 in class II/III (P less than 0.01) but did not change in class I (12.4 vs 11.8, ns). There was also a greater increase in heart rate (HR) in class II/III subjects (P less than 0.05). The duration of exercise was correlated with resting PV (r = 0.48, P less than 0.025) but was correlated best with the change in blood momentum (PV x Stroke volume x HR) between rest and peak exercise (r = 0.80, P less than 0.001). Thus Doppler velocimetry can give quantitative information on the response to exercise which discriminates between grades of ventricular dysfunction and is predictive of exercise capacity.

Adult↗
PubMed1992

A prospective, randomised, cross-over study comparing the effects of clomiphene citrate and cyclofenil on endometrial morphology in the luteal phase of normal, fertile women.

OBJECTIVE: To examine the effect of two anti-oestrogens, clomiphene citrate and cyclofenil, on endometrial morphology in the luteal phase. DESIGN: A prospective, randomised, cross-over study. SETTING: Jessop Hospital for Women, Sheffield, UK. SUBJECTS: 10 women who were previously fertile and regularly cycling. INTERVENTION: The administration of clomiphene citrate or cyclofenil in the treatment cycles. A LH timed endometrial biopsy was taken on day LH + 6. MAIN OUTCOME MEASURES: Histological dating and morphometric analysis of the endometrial sample. RESULTS: Only one out of 10 subjects had abnormal endometrium. There was no difference in the results between cycles treated with clomiphene citrate and cyclofenil. CONCLUSIONS: Clomiphene citrate or cyclofenil does not have a major adverse effect on endometrial morphology in the luteal phase of normal fertile subjects. The possible adverse effects of anti-oestrogens on endometrium may have been previously overestimated.

Adult↗
PubMed1992

Validation of the beat to beat measurement of blood velocity in the human ascending aorta by a new high temporal resolution Doppler ultrasound spectral analyser.

OBJECTIVE: To develop and validate a high temporal resolution spectral analysis system for Doppler measurements of blood velocity in the ascending aorta. DESIGN: An observational laboratory and clinical study comparing Doppler velocity-based measurements with fluid collection, electromagnetic flow catheters and probes, and thermodilution. SETTING: Tertiary referral cardiology unit and cardiac catheter laboratory. PATIENTS: Patients undergoing routine cardiac catheterisation for ischaemic heart disease, cardiac failure, and primary pulmonary hypertension. RESULTS: There was good agreement between Doppler-derived and electromagnetic cuff or catheter measurements of velocity in an experimental flow rig (SD of differences 4.75% for velocity integral) and in the patients (SD of differences 4% for velocity integral). There was also reasonably good agreement between simultaneous Doppler-derived and thermodilution-estimated cardiac output measurements in patients undergoing cardiac catheterisation (SD of differences 12.6%). CONCLUSIONS: This new method of high temporal resolution spectral analysis improves the resolution of rapidly changing blood velocities and may improve the ability to describe blood velocity patterns in the ascending aorta.

Adolescent↗
PubMed1992

Kinetics of urea exchange in air-filled and fluid-filled rat lungs.

Urea has been used as an indicator for estimating 1) the dilution of epithelial lining fluid (ELF) that occurs during bronchoalveolar lavage (BAL) and 2) the permeability-surface area product (PS) of the pulmonary endothelium to this solute. Because relatively little is known about how urea equilibrates with fluid in the lung tissues and airspaces, we have undertaken a study of the kinetics of movement from the vasculature into the tissues of isolated, perfused rat lungs. Although instillation of 5 ml of 154 mM saline into the airspaces of this preparation increased the calculated extravascular volume of 3HOH from 0.64 +/- 0.23 to 2.10 +/- 0.58 ml (SE, n = 6) during a single transit through the pulmonary circulation, it did not have a detectable effect on the distribution of [14C]urea in the lung tissues. However, leakage of [14C]urea into saline within the airspaces was detected during constant infusions: concentrations in the airspace fluid reached 1.1 +/- 0.2% of those in the perfusate by 90 s and 1.90 +/- 0.2% at 120 s, levels that would significantly reduce estimates of the dilution of ELF by BAL. In contrast, concentrations of 99mTc-diethylenetriaminepentaacetic acetic acid (DTPA) in the airspaces remained < 0.2% of those in the perfusate, suggesting that 99mTc-DTPA may be a superior indicator for estimating dilution of ELF by BAL.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed1992

A simple technique for laparoscopic gastrostomy.

While endoscopically placed gastrostomy tubes are routinely simple, they are not always feasible. Endoscopic technique also does not uniformly secure the tube to the abdominal wall, which presents possible complications, including leakage, accidental early tube removal, intraperitoneal catheter migration and necrosis of the stomach or abdominal wall because of excessive traction. Presented herein is a technique that is rapid, simple and eliminates some of these potential complications. The technique is easily combined with other operative procedures, such as tracheostomy, is done under direct vision, can be performed quickly with intravenous sedation and local anesthetic and is a safe method of tube placement for enteral feeding or gastric decompression.

Gastrostomy↗
PubMed1991

Lobster troponin C: amino acid sequences of three isoforms.

We have determined the amino acid sequences of the three major isoforms of lobster troponin C, using protein chemistry methods. Each isoform contains 150 amino acid residues, with a calculated Mr of 17,000 +/- 100. Sequence differences occur in all regions of the polypeptides, indicating that the isoforms are products of three different genes, rather than alternative transcripts of a single gene. Analysis of the sequences predicts that functional Ca(2+)-binding sites are present only in regions II and IV of four ancestral regions.

Amino Acid Sequence↗
PubMed1991

Serologic and chemical differentiation of human lambda III light chain variable regions.

Human lambda L chains of a major V lambda subgroup, V lambda III, have been differentiated serologically and chemically into three V lambda III sub-subgroups designated V lambda IIIa, V lambda IIIb, and V lambda IIIc. Antisera prepared against lambda III Bence Jones proteins were obtained that recognized distinctive V lambda III-related epitopes expressed by monoclonal lambda III L chains. After appropriate absorption, these reagents were rendered specific for three distinct populations of lambda III proteins--lambda IIIa, lambda IIIb, and lambda IIIc. The antisera were used in comparative immunodiffusion analyses of 28 monoclonal lambda III L chains, 10 of which were classified as lambda IIIa, 4 as lambda IIIb, and 14 as lambda IIIc. The isotypic nature of the three lambda III sub-subgroups was demonstrated serologically through analyses of lambda-chains derived from the serum IgG molecules of normal individuals. The amino acid sequences of five serologically classified lambda III chains, which included members of the three V lambda III sub-subgroups, had been previously determined. This information, in addition to our establishment of the complete (or virtually complete) V region sequence of 15 and the partial sequence of eight other lambda IIIa, lambda IIIb, and lambda IIIc proteins, made it possible to correlate chemical data with serologic classification. Proteins within each of the three serologically-classified lambda III sub-subgroups typically possessed a high degree (approximately 83%) of intra-sub-subgroup sequence homology that included both framework and complementarity determining region residues. Furthermore, within the framework and complementarity determining regions, sub-subgroup-specific residues were identified. Taken together, these data reveal that the human V lambda III genome consists of (at least) three distinct V lambda IIIa, V lambda IIIb, and V lambda IIIc germline genes that encode for lambda IIIa, lambda IIIb, and lambda IIIc L chains, respectively.

Amino Acid Sequence↗