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Biomedical subjects

J Payne

Publications and source records attributed to J Payne.

At least 55 records · Page 3Linked to original sources
PubMed1998

The precursor form of the human kallikrein 2, a kallikrein homologous to prostate-specific antigen, is present in human sera and is increased in prostate cancer and benign prostatic hyperplasia.

Prostate-specific antigen (PSA, hK3) is a diagnostic marker for prostatic cancer but lacks the specificity to sufficiently distinguish between prostatic cancer and benign prostatic hyperplasia (BPH). Human glandular kallikrein 2 (hK2) has been proposed as a potential diagnostic marker for prostate cancer that could complement the current PSA test. Recently we demonstrated that proPSA is present in prostate cancer sera. This study examines the expression of prohK2 in prostate cells and its presence in human sera. Western blot analysis was used to assess prohK2 expression in the human carcinoma cell line, LNCaP. A highly specific and sensitive dual monoclonal immunoassay for prohK2 was developed and used to assess the presence of prohK2 in human sera. prohK2 was detected in the spent media of LNCaP cells. Furthermore, prohK2 was present at immunodetectable concentrations in human sera, and its concentration was increased in prostatic cancer and BPH. These results indicate for the first time that prohK2 is secreted by human prostate cells and is a major component of uncomplexed (free) hK2 in human sera. In addition, prohK2 in human sera is associated with prostate disease and thus may be a useful marker for prostatic cancer and BPH.

Antibodies, Monoclonal↗
PubMed1997

Spinal cord oligodendrocytes develop from a limited number of migratory highly proliferative precursors.

Oligodendrocytes are responsible for myelin formation in spinal cord white matter. In the mature spinal cord, the majority of white matter is localized peripherally. During early development, however, the first oligodendrocyte precursors arise in the ventral ventricular zone of the developing cord. Thus, prior to myelination, both migration and proliferation of oligodendrocyte precursors must occur. When and where these events occur is currently unclear. In the chick spinal cord, oligodendrocyte precursors express antigens recognized by the monoclonal antibody O4. Here we show that all chick spinal cord oligodendrocytes are derived from O4+ cells and all O4+ cells appear to give rise to oligodendrocytes. Analysis of the number and distribution of oligodendrocyte precursors in chick spinal cord at different stages of development suggests that relatively few cells migrate from the ventricular source which then proliferate extensively in white matter. This migration is guided by general dispersive cues. Clonal analysis of oligodendrocyte development in cultures derived from different regions of the rodent spinal cord indicated that the cells that initially populate dorsal and peripheral spinal cord retained similar clonal properties to those in ventral spinal cord, suggesting the migrating cells were immature, highly proliferative precursors. Consistent with these results, BrdU incorporation studies indicate that glial proliferation is extensive and persistent in postnatal rat spinal cord white matter. Together, these studies suggest that spinal cord white matter is initially populated by very immature precursors that then undergo extensive local proliferation prior to myelination.

Animals↗
PubMed1997

Spina bifida occulta in homozygous Patch mouse embryos.

In normal embryos, mRNA encoding platelet-derived growth factor A (PDGF A) and the platelet-derived growth factor receptor alpha (PDGFR alpha) are found within and adjacent to the site of vertebral development, the sclerotome. These patterns of expression are consistent with PDGF action on the developing sclerotome and dermis. Homozygous Patch (Ph) mutant mouse embryos lack the receptor gene (Pdgfra) due to an extensive deletion at that locus. Consistent with the spatial pattern of Pdgfra expression, striking deformities are found in the spine and ribcage of Ph/Ph embryos. In particular, we show that late-gestation Ph/Ph embryos have occult spina bifida involving the entire spinal column. We have analyzed the progression of the axial defects in homozygous Patch embryos in detail. By late gestation it appears that the components of the vertebrae are present, yet the neural arches of the spine are misshapen. We propose that PDGF A is required for proper positioning of the neural arch condensation at all axial levels. Furthermore, since the neural tube appears to close normally, we suggest that spina bifida in the Ph homozygote is caused primarily by a somitic mesoderm abnormality rather than a neural tube defect.

Animals↗
PubMed1997

Glucose transporter Glut 5 expression in microglial cells.

Glut 5 is a member of a family of facilitative glucose transporter proteins that are involved in the transportation of glucose and/or fructose across plasma membranes. Glut 5 is one of three isoforms expressed in brain. Using immunocytochemical and immunoblotting techniques in formalin fixed tissue, we have shown that Glut 5 is exclusively expressed in microglial cells of the human and rat brain. Our data demonstrate that unlike other microglial markers, Glut 5 can be used as a microglial marker in formalin fixed tissue.

Adolescent↗
PubMed1997

Telementoring: pushing the telemedicine envelope.

Telemedicine offers significant advantages in bringing consulting support to distant colleagues. Our aim in this study was to evaluate the role of telementoring in the training of advanced laparoscopic surgical procedures. Student surgeons received a uniform training format to enhance their laparoscopic skills and intracorporeal suturing techniques and specific procedural training in laparoscopic colonic resections and Nissen fundoplication. Subsequently, operating rooms were equipped with three cameras. A telestrator (teleguidance device), instant replay (to critique errors), and CD-ROM programs (to provide reference information) were used as intraoperative, educationally assistant tools. In phase 1, four colonic resections were performed with the mentor in the operating room (group A), and four colonic resections were performed with the mentor on the hospital grounds but not in the operating room (group B). The voice and video signals were received at the mentor's location using coaxial cable. In phase 2, two Nissen fundoplications were performed with the mentors in the operating room (group C), and two Nissen fundoplications were performed with the mentors 5 miles away from the operating room (group D) using existing land lines at the T1 level. We found no differences in the performances of the surgeons or the outcomes of the operations between groups A and B and groups C and D. Intraoperative problems were tackled effectively. Preliminarily, we conclude that the telementoring concept is potentially a safe and cost-effective option for advanced training in laparoscopic operations. Further investigation is necessary before routine transcontinental patient applications are attempted.

Colectomy↗
PubMed1996

DNA repair in cisplatin-sensitive and resistant human cell lines measured in specific genes by quantitative polymerase chain reaction.

More than 80% of patients with testicular germ cell tumours (TGCT) are cured using cisplatin-based combination chemotherapy, and resistance to cisplatin is the final barrier to the cure of nearly all patients with this disease. In this study, we used quantitative polymerase chain reaction (Q-PCR) to investigate the role of DNA repair in cisplatin resistance in two genes, one transcribed and one not transcribed. Three pairs of cisplatin-sensitive and resistant cell lines were used, two derived from TGCT and one from a bladder cancer. In these pairs of sublines, we observed no major differences between the repair of cisplatin-induced damage in the transcribed and nontranscribed genes, nor did there appear to be any relationship between DNA repair capacity and the development of cisplatin resistance. Despite the strong indication that the sensitivity of testis tumour cells to cisplatin is related to their reduced ability to repair cisplatin-damaged DNA, these cells apparently do not become resistant to cisplatin by acquiring DNA repair capacity.

Antineoplastic Agents↗
PubMed1996

Assessment of coronary arterial flow and flow reserve in humans with magnetic resonance imaging.

BACKGROUND: The noninvasive measurement of absolute epicardial coronary arterial flow and flow reserve would be useful in the evaluation of patients with coronary circulatory disorders. Phase-contrast magnetic resonance imaging (PC-MRI) has been used to measure coronary arterial flow in animals, but its accuracy in humans is unknown. METHODS AND RESULTS: Twelve subjects (7 men, 5 women: age 44 to 67 years) underwent PC-MRI measurements of flow in the left anterior descending coronary artery or one of its diagonal branches at rest and after administration of adenosine (140 microgram . kg(-1) . min (-1) IV). Immediately thereafter, intracoronary Doppler velocity (IDV) and flow measurements were made during cardiac catheterization at rest and after intravenous administration of adenosine. For the 12 patients, the correlation between MRI and invasive measurements of coronary arterial flow and coronary arterial flow reserve was excellent: coronary flow (MRI) (mL/min)= 0.85 x coronary flow (IDV) (mL/min)+17 (mL/min), r=.89, and coronary flow reserve (MRI) =0.79 x coronary velocity reserve (IDV) + 0.34, r=.89. For the range of coronary arterial flows (18 to 161 mL/min) measured by MRI, the limit of agreement between MRI and catheterization measurements of flow was -13+/-30 mL/min; for the range of coronary reserves (0.7 to 3.7) measured by MRI, the limit of agreement between the two techniques was 0.1+/-0.4. CONCLUSIONS: Cine velocity-encoded PC-MRI can noninvasively measure absolute coronary arterial flow in the left anterior descending artery in humans. PC-MRI can detect pharmacologically induced changes in coronary arterial flow and can reliably distinguish between those subjects with normal and abnormal coronary artery flow reserve.

Adenosine↗
PubMed1996

Exploitation of a chromosomally integrated lactose operon for controlled gene expression in Lactococcus lactis.

Lactococcus lactis MG5267 is a plasmid-free strain in which the lactose operon is integrated in the bacterial chromosome. The chromosomal lacG gene which encodes phospho-beta-galactosidase was inactivated by a double cross-over integration event. Unexpectedly, the resultant mutant was shown to retain a Lac-positive phenotype. The lysin gene from Listeria monocytogenes bacteriophage LM-4 was subsequently integrated into the chromosome of this strain such that expression of the heterologous gene was mediated by the lactose operon promoter. Expression of the lysin gene was shown to be regulated by growth on lactose. This represents an important strategy for the controlled and stabilised expression of biotechnologically useful genes in L. lactis.

Bacteriophages↗
PubMed1996

Sequencing of a 35.71 kb DNA segment on the right arm of yeast chromosome XV reveals regions of similarity to chromosomes I and XIII.

In a shotgun approach we sequenced the cosmid pEOA284 containing a fragment derived from the right arm of chromosome XV of Saccharomyces cerevisiae. An analysis of the sequence revealed that it contained open reading frames (ORFs) corresponding to the known genes SLY41, SPS4, COT1, FAA1, PMT3, PRO2 and MYO2. Of the 18 unknown ORFs, five are contained totally within, and two, O6105 and O6163, partially overlap other ORFs. ORF O6116 and O6139 have putative introns. Regions of similarity with chromosomes I and XIII have been uncovered. Interestingly, most of the paired ORFs encode proteins of the same gene family. The relatedness of these ORFs suggests gene duplication.

Amino Acid Sequence↗
PubMed1996

Postoperative analgesia by continuous extradural infusion of ropivacaine after upper abdominal surgery.

Ropivacaine is a new local anaesthetic with advantages that suggest an important role in the provision of postoperative analgesia. The main aim of this study was to investigate the dose-response relationship of extradural infusion of ropivacaine. We studied 36 ASA I-III patients undergoing upper abdominal surgery during general anaesthesia and extradural block (catheter insertion at T6-9) using 0.5% ropivacaine in a randomized, double-blind study. After surgery nine patients each received an extradural infusion of either ropivacaine 0.1%, 0.2%, 0.3% or saline at a rate of 10 ml h-1 for 21 h. All patients had access to i.v. morphine via a PCA device. The ropivacaine groups consumed significantly less morphine over the 21-h infusion period than the saline group (medians: saline 75 mg; 0.1% ropivacaine 32 mg; 0.2% ropivacaine 39 mg; 0.3% ropivacaine 13 mg) (P < 0.05). Pain (VAS scores) at rest was significantly lower in all ropivacaine groups than in the saline group after 4 h of infusion (medians: saline 45 mm; 0.1% ropivacaine 15 mm; 0.2% ropivacaine 12 mm; 0.3% ropivacaine 0 mm). Pain on coughing was significantly less in all ropivacaine groups than in the saline group after 4 h infusion (medians: saline 67 mm; 0.1% ropivacaine 44 mm; 0.2% ropivacaine 33 mm; 0.3% ropivacaine 0 mm) and for 0.2% and 0.3% ropivacaine at later times. Motor block was negligible throughout the infusion. Patient satisfaction was higher in the 0.2% and 0.3% ropivacaine groups than in the two other groups.

Abdomen↗
PubMed1996

A novel 66-kilodalton protein complexes with Rrn6, Rrn7, and TATA-binding protein to promote polymerase I transcription initiation in Saccharomyces cerevisiae.

We report the cloning of RRN11, a gene coding for a 66-kDa protein essential for transcription initiation by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae. Rrn11 specifically complexes with two previously identified transcription factors, Rrn6 and Rrn7 (D. A. Keys, J. S. Steffan, J. A. Dodd, R. T. Yamamoto, Y. Nogi, and M. Nomura, Genes Dev. 8:2349-2362, 1994). The Rrn11-Rrn6-Rrn7 complex also binds the TATA-binding protein and is required for transcription by the core domain of the Pol I promoter. Therefore, we have designated the Rrn11-Rrn6-Rrn7-TATA-binding protein complex the yeast Pol I core factor. A two-hybrid assay was used to demonstrate involvement of short leucine heptad repeats on both Rrn11 and Rrn6 in the in vivo association of these two proteins. This assay also verified the previously described strong association between Rrn6 and Rrn7, independent of the Rrn6 leucine repeat.

Amino Acid Sequence↗
PubMed1995

Three-dimensional structure of cat tibialis anterior motor units.

The motor unit is the basic unit for force production in a muscle. However, the position and shape of the territory of a motor unit within the muscle have not been defined precisely. The territories of five motor units in the cat tibialis anterior muscle were reconstructed three-dimensionally (3-D) from tracings of the glycogen-depleted fibers belonging to each unit. The motor unit territories did not span the entire length of the muscle and their cross-sectional areas tapered along the proximodistal axis producing a conical shape. In addition, the position of the territory of each unit shifted in an anterior-posterior plane along the longitudinal axis of the muscle, presumably as a consequence of the pinnation of the fibers. The area of the motor unit territory at any given level along the proximodistal axis was highly correlated with the number of fibers within the territory at that level. Connective tissue boundaries (outlining fascicles) appeared to have a strong influence on the shape of the territory, territories showed abrupt changes at connective tissue boundaries as groups of motor unit fibers within a fascicle often terminated together while motor unit fibers in neighboring fascicles did not terminate. It is likely that the mechanical impact of the recruitment of a motor unit is affected by the location and shape of motor units within the same muscle area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Increased lipolysis to beta-adrenergic stimulation after dehydroepiandrosterone treatment in rats.

Young adult male rats were treated with 4 mg dehydroepiandrosterone (DHEA)/100-g diet for 4 wk or were fed the same purified diet unadulterated (51 carbohydrate:20 fat: 23.5 protein; wt/wt). After 1 wk body weight and fat mass of the DHEA-fed rats were significantly less than the controls. By the end of week 3, fat-free mass of the DHEA rats was less than the controls. Neither food intake nor resting metabolism, measured by indirect calorimetry, was different between groups. Isolated epididymal adipocytes of DHEA rats were significantly smaller and isoproterenol (x 10(7) M) stimulation of glycerol release was 53% greater (P < 0.01) than the controls. Basal rate of glycerol release increased significantly for both groups in response to the adenosine inhibitor adenosine deaminase; there were no significant interaction effects. Inhibition of lipolysis by the adenosine analogue phenylisopropyladenosine was similar between groups. Findings support the hypothesis that DHEA reduces adiposity directly by increased lipolysis, but the mechanism of action does not involve a change in the antilipolytic function of adenosine.

Adenosine Deaminase↗
PubMed1995

Early development and dispersal of oligodendrocyte precursors in the embryonic chick spinal cord.

Oligodendrocytes, the myelinating cells of the vertebrate CNS, originally develop from cells of the neuroepithelium. Recent studies suggest that spinal cord oligodendrocyte precursors are initially localized in the region of the ventral ventricular zone and subsequently disperse throughout the spinal cord. The characteristics of these early oligodendrocyte precursors and their subsequent migration has been difficult to assay directly in the rodent spinal cord due to a lack of appropriate reagents. In the developing chick spinal cord, we show that oligodendrocyte precursors can be specifically identified by labeling with O4 monoclonal antibody. In contrast to rodent oligodendrocyte precursors, which express O4 immunoreactivity only during the later stages of maturation, in the chick O4 immunoreactivity appears very early and its expression is retained through cellular maturation. In embryos older than stage 35, O4+ cells represent the most immature, self-renewing, cells of the chick spinal cord oligodendrocyte lineage. In the intact chick spinal cord, the earliest O4+ cells are located at the ventral ventricular zone where they actually contribute to the ventricular lining of the central canal. The subsequent migration of O4+ cells into the dorsal region of the spinal cord temporally correlates with the capacity of isolated dorsal spinal cord to generate oligodendrocytes in vitro. Biochemical analysis suggests O4 labels a POA-like antigen on the surface of chick spinal cord oligodendrocyte precursors. These studies provide direct evidence for the ventral ventricular origin of spinal cord oligodendrocytes, and suggest that this focal source of oligodendrocytes is a general characteristic of vertebrate development.

Animals↗
PubMed1994

Effects of low-dose aspirin on in vitro platelet aggregation in the early minutes after ingestion in normal subjects.

Aspirin interferes with platelet aggregation by inhibiting the metabolism of arachidonic acid to thromboxane A2. Although both high- and low-dose aspirin therapies are effective for secondary prophylaxis in patients with atherosclerotic vascular disease, the acute response to low-dose aspirin therapy is controversial. Eighteen volunteer subjects ingested 81, 162, or 324 mg of aspirin in a longitudinal crossover study design. Initial doses were randomly assigned and dosing intervals were separated by 2 weeks. Platelet aggregation in response to 0.9 mM arachidonic acid was measured at baseline, 15, 30, 60, and 90 minutes after ingestion. Thromboxane B2 production was assayed on simultaneously obtained samples after stimulation with arachidonic acid. The median inhibition of aggregation was 97%, 97%, and 97% 15 minutes after ingestion of 81, 162, and 324 mg, respectively. Four subjects had < 20% inhibition 15 minutes after ingesting 81 mg, but all 4 had > 90% inhibition after 30 minutes. Thromboxane B2 production declined by > 93% in all subjects at each dose. There was no difference between doses in inhibition of thromboxane B2 production.

Administration, Oral↗
PubMed1994

The burden of Haemophilus influenzae type b disease in Australia and an economic appraisal of the vaccine PRP-OMP.

OBJECTIVES: To estimate the incidence and sequelae of Haemophilus influenzae type b disease (Hib) in the Australian population, and to evaluate the costs and outcomes of a vaccination program using the vaccine PRP-OMP at two, four and 12 months. DESIGN: The evaluation was based on a decision analytic model developed by Merck Sharp and Dohme (Australia) Pty Ltd, to predict the number of children who would contract Hib, and suffer mild or severe sequelae or die as a result. The state of health of a cohort of children was modelled each month over a five-year period. A survey of medical records and interviews with parents of children who contracted meningitis in Western Australia from 1984-1990 was undertaken to provide data on the extent and costs of sequelae. RESULTS: The incidence of Hib among non-Aboriginal Australians under five years of age was estimated as 53 per 100,000, and 460 per 100,000 among Aborigines. In a single year at least 630 children may contract Hib, up to 19 may die, and a further 46 may have neurological damage, this being severe in up to 18 children. The number of deaths could be reduced by 17 per year and a further 25 cases of severe and 16 cases of mild disability could be averted. At a price of $20 per dose, and a 5% discount rate, the expected cost per year of life extended by a vaccination program is $3148. When adjusted for the increased number of years without neurological impairment, the incremental cost per quality adjusted life year (QALY) is $1965. Compared with a single vaccine at 18 months, the incremental cost per additional QALY gained is $5047. A separate analysis of the Aboriginal population showed that the proposed vaccination program would be of significant benefit, leading to a saving of resources.

Age Factors↗
PubMed1994

Stability of amoxycillin and potassium clavulanate in co-amoxiclav oral suspension.

A study was carried out using high performance liquid chromatography (HPLC) to determine the chemical stability of amoxycillin and potassium clavulanate in 250/62 co-amoxyclav oral suspension (Augmentin), stored at room temperature (RT, 20 degrees C) and 8 degrees C over a period of 11 days. The suspension was judged to be acceptable if its components maintained at least 90% of their label concentrations. During the test period, the amoxycillin component was found to be more stable than the clavulanate. Amoxycillin was stable for 7 days at both temperatures. Potassium clavulanate maintained at least 90% of its initial concentration for 7 days at 8 degrees C but showed more than 40% degradation in the same time period at RT. For potassium clavulate the shelf-life, or time taken for the original concentration to drop to 90% of its value (t90) at RT was found to be 2 days.

Amoxicillin↗