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Biomedical subjects

C Murphy

Publications and source records attributed to C Murphy.

At least 19 recordsLinked to original sources
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↗
PubMed1991

Histone genes are located at the sphere loci of Xenopus lampbrush chromosomes.

In the anuran Xenopus, as has been demonstrated previously in several species of urodele Amphibia, histone genes lie at the sphere organizer loci of the lampbrush chromosomes. They were located by in situ hybridization of a 3H-labelled histone H4 anti-sense cRNA probe applied to lampbrush preparations in which transcript RNA had been retained, and likewise to preparations in which transcripts were absent but whose DNA had been denatured prior to hybridization. In Xenopus the histone genes lie in intimate association with the spheres that are attached to the lampbrush chromosomes, but they are absent from spheres that lie free in the germinal vesicle. The Anura separated from the Urodela several hundred million years ago, so the sphere organizer/histone gene association is of great antiquity. This suggests that the association has a functional significance, though it is one that has yet to be discovered.

Animals↗
PubMed1991

A mass spectrometry method for mapping the interface topography of interacting proteins, illustrated by the melittin-calmodulin system.

The shielding of lysine groups from acetylation by acetic anhydride has been used to identify the regions of calmodulin in contact with melittin in the 1:1 complex. The estimation of the degree of acetylation was done by examining cyanogen bromide and cyanogen bromide/trypsin digests by mass spectrometry. Evidence was obtained that lysines-21, -75, and -148 are protected to some extent, with the implication that both the N- and C-terminal lobes and the connecting strand are involved in the interaction.

Acetylation↗
PubMed1991

Small nuclear ribonucleoproteins and heterogeneous nuclear ribonucleoproteins in the amphibian germinal vesicle: loops, spheres, and snurposomes.

We have examined the distribution of snRNPs in the germinal vesicle (GV) of frogs and salamanders by immunofluorescent staining and in situ nucleic acid hybridization. The major snRNAs involved in pre-mRNA splicing (U1, U2, U4, U5, and U6) occur together in nearly all loops of the lampbrush chromosomes, and in hundreds to thousands of small granules (1-4 microns diameter) suspended in the nucleoplasm. The loops and granules also contain several antigens that are regularly associated with snRNAs or spliceosomes (the Sm antigen, U1- and U2-specific antigens, and the splicing factor SC35). A second type of granule, often distinguishable by morphology, contains only U1 snRNA and associated antigens. We propose the term "snurposome" to describe the granules that contain snRNPs ("snurps"). Those that contain only U1 snRNA are A snurposomes, whereas those that contain all the splicing snRNAs are B snurposomes. GVs contain a third type of snRNP granule, which we call the C snurposome. C snurposomes range in size from less than 1 micron to giant structures greater than 20 microns in diameter. Usually, although not invariably, they have B snurposomes on their surface. They may also contain from one to hundreds of inclusions. Because of their remarkably spherical shape, C snurposomes with their associated B snurposomes have long been referred to as spheres or sphere organelles. Most spheres are free in the nucleoplasm, but a few are attached to chromosomes at specific chromosome loci, the sphere organizers (SOs). The relationship of sphere organelles to other snRNP-containing structures in the GV is obscure. We show by immunofluorescent staining that the lampbrush loops and B snurposomes also react with antibodies against heterogeneous nuclear ribonucleoproteins (hnRNPs). Transcription units on the loops are uniformly stained by anti-hnRNP and anti-snRNP antibodies, suggesting that nascent transcripts are associated with hnRNPs and snRNPs along their entire length, perhaps in the form of a unitary hnRNP/snRNP particle. That B snurposomes contain so many components involved in pre-mRNA packaging and processing suggests that they may serve as sites for assembly and storage of hnRNP/snRNP complexes destined for transport to the nascent transcripts on the lampbrush chromosome loops.

Animals↗
PubMed1991

Enlisting the eccentric photoscreener in a public hospital eye department.

We analysed retrospectively non-acute new referrals of children to Waikato Hospital over one year. It was found that children were required to wait unacceptably long to be seen. Almost half the children with established amblyopia were not seen until after the age of five years (42% were not referred until after that age). On the other hand, half the children seen had no significant pathology, and the high level of non-attendance also wasted clinic time. An attempt was made to address these problems by holding regular screening clinics using a photoscreener, assessing all children within three weeks of referral so that children with pathology could be examined and treated promptly. Preliminary investigations into mass community photoscreening produced an average recall rate of 11% (54% of whom fell into our definition of pathological). We feel that enlisting the photoscreener has provided a much more efficient paediatric service, which it is hoped will lead to a reduction in visual loss due to amblyopia.

Adolescent↗
PubMed1991

On mischief.

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Child, Preschool↗
PubMed1991

The rhinologic evaluation of Alzheimer's disease.

Olfactory dysfunction is currently not listed among the NINCDS-ADRDA clinical criteria for the diagnosis of Alzheimer's disease. There is a large amount of psychophysical and neuropathologic evidence to suggest that patients with Alzheimer's type dementia have olfactory system abnormalities. The rhinologic status of this group has not been characterized. The authors examined 21 Alzheimer's patients and 21 age-matched controls to determine whether 1. the Alzheimer's group, in fact, had a diminished sense of smell, and whether 2. rhinologic factors were responsible for this nasal dysfunction. The findings support a neurologically mediated phenomenon as the cause for significant impairment in olfactory function in patients with probable Alzheimer's disease.

Aged↗
PubMed1991

Disulfide bonds in native and recombinant fish growth hormones.

Disulfide linkages were characterized for the first time in a fish growth hormone. Trypsin digestion of chum salmon growth hormone, followed by mass spectrometry established that Cys-49 is linked to Cys-161, while Cys-178 is linked to Cys-186. This is analogous to the big loop, little loop pattern found in human growth hormone. Ninety-three percent of the primary structure of a recombinant rainbow trout growth hormone whose cDNA codes for the same amino acid sequence as chum salmon growth hormone was confirmed by mass spectrometric peptide mapping.

Amino Acid Sequence↗