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Biomedical subjects

M Jenkins

Publications and source records attributed to M Jenkins.

At least 19 recordsLinked to original sources
PubMed2003

Evaluation of a commercial ELISA for detecting Norwalk-like virus antigen in faeces.

A commercially available enzyme immunoassay, the IDEIA Norwalk-like virus (NLV) enzyme linked immunosorbent assay (ELISA; Dako Cytomation, Ely, UK) for detecting NLV antigen in faecal samples and determining the NLV genogroup was evaluated. The performance of the ELISA was compared with that of electron microscopy and the reverse transcription polymerase chain reaction by testing a panel of faecal samples collected from patients involved in outbreaks of gastroenteritis. When compared with reverse transcription-polymerase chain reaction (RT-PCR), the ELISA had a sensitivity and specificity of 55.5 and 98.3%, respectively. This compares with a sensitivity and specificity for EM of 23.9 and 99.2%, respectively. The sensitivity and specificity of the ELISA for determining the aetiology of a Norwalk virus-like outbreak, based on two or more positive samples within an outbreak, were 52.2 and 100% when two samples were collected from an outbreak and 71.4 and 100% when six or more samples were collected. The ELISA correctly identified the NLV genogroups of viruses previously characterised by partial DNA sequencing. The ELISA is a suitable alternative to the preliminary screening by EM for investigating outbreaks of gastroenteritis. Outbreaks, negative by ELISA should be examined by RT-PCR in order to detect strains non-reactive in the assay and virus strains from representative ELISA positive outbreaks should be characterised fully to allow the genetic diversity of NLVs co-circulating in the population to be described.

Antigens, Viral↗
PubMed2002

Comparison of tests for viable and infectious Cryptosporidium parvum oocysts.

The purpose of this study was to compare different assays for viable Cryptosporidium parvum incubated in water at a temperature commonly found in the environment. C. parvum oocysts were stored in sterile water for 9 months at 15 degrees C. A sample was removed monthly and analyzed by five different assays to determine oocyst viability. Mouse infection and cell culture showed that C. parvum oocysts remained viable and infectious when stored for 7 months at this temperature. Fluorescence in situ hybridization (FISH) using probes directed to ribosomal RNA was also applied to these oocysts. The proportion of FISH-positive oocysts was 70-80% for the first 2 months of storage, decreased and remained nearly constant at 40-50% for 3-7 months, then decreased to 20% by 8 months, and to 0% by 9 months. Amylopectin content and mRNA for amyloglucosidase (CPAG), as measured by RT-PCR, decreased much more rapidly. By 3 months and for the remainder of the incubation period, amylopectin content was 20% of the original amount present in the oocysts. The CPAG RT-PCR signal at 3 months was 50% of that observed after 1 month storage, 20% at 4 months, and was not detected thereafter. Thus, results from cell culture and mouse infection assay exhibited the best agreement, the FISH assay showed modest agreement with these assays, and CPAG RT-PCR and the amylopectin assay displayed marginal agreement with the other three assays.

Amylopectin↗
PubMed2002

Safety toxicity study of plasmid-based IL-12 therapy in Cynomolgus monkeys.

We have investigated the potential toxicity of hlL-12 DNA plasmid formulated with 5% polyvinylpyrrolidone (PVP) administered twice weekly via subcutaneous injections to Cynomolgus monkeys for four weeks, and have evaluated recovery from any effects of the test article over a four-week treatment-free period. Doses of the formulated hIL-12 plasmid were selected based on anti-tumour efficacy studies previously conducted in mice. The duration of the study and the frequency of dosing were designed to support clinical trials. No clinical signs indicative of an adverse effect of administration of formulated hIL-12 plasmid were observed. There were no apparent effects of the formulated hIL-12 plasmid on body weights or on serum chemistry, haematology, coagulation or urinalysis parameters. No treatment-elated ocular abnormalities were evident. In addition, examination of the electrocardiograms from all monkeys at the pre-study, week-4, and week-8 time points did not reveal any treatment-related effects. No treatment-related gross lesions were noted at days 28 or 57. Slight histopathological changes associated with high doses of PVP vehicle were observed at both time points. These results suggested that the administration of formulated hIL-12 plasmid at a dose level up to 18 mg kg(-1) dose twice per week for four weeks to experimentally naïve Cynomolgus monkeys did not result in significant toxicity. These results support further testing of this gene therapy in clinical trials.

Animals↗
PubMed2001

Factor V Leiden and factor V R2 allele: high-throughput analysis and association with venous thromboembolism.

Thrombophilia is a multigenic disease in which the combination of genetic polymorphisms increases the risk of deep vein thrombosis (DVT). The rapid identification of these genetic combinations requires high-throughput analysis of single nucleotide polymorphisms (SNPs). The TaqMan fluorogenic 5'-->*3' nuclease assay (PE/Applied Biosystems, Foster City, CA) with custom-designed primers, probes and controls has provided a highly efficient platform for high throughput. This assay was used to rapidly detect two SNPs, FV Leiden (G1691A) and FV A4070G (R2 allele), in a study of 6295 subjects. With one thermal cycler, we completed sample set-up, PCR and analysis on 84 samples in 3 h with an additional 12 wells containing 4 "no template controls" (NTC), 4 "allele-1 controls", and 4 "allele-2 controls" in a 96-well plate. When additional thermal cyclers were used and more assays were set up while the initial sets of reactions were in the PCR machines, the output could correspondingly be increased. The TaqMan assay was extremely accurate, avoided contamination by using uracil-N-glycolase (UNG) in a single, closed tube, and offered the possibility for additional automation with robotic equipment to implement the PCR. This TaqMan assay facilitates high throughput to screen large populations quickly and economically while utilizing a simple protocol that requires minimal expenditure of personnel time. Our results demonstrated a prevalence of the R2 allele of 11.9% in U.S. Caucasians, 5.6% in African-Americans, 13.4% in Asian or Pacific Islanders and 11.3% in Hispanics. No association between venous thromboembolism and the R2 allele was noted, and furthermore no interaction with FV Leiden was observed.

Alleles↗
PubMed2000

Peptoid-containing collagen mimetics with cell binding activity.

Collagen mimetic peptides containing the peptoid residue Nleu (Goodman Bhumralkar, Jefferson, Kwak, Locardi. Biopolymers 1998;47:127-142) were tested for interactions with epithelial cells and fibroblasts. Molecules containing the sequence Gly-Pro-Nleu with a minimum of nine repeats showed cell binding activity. The activity of these molecules appeared to be conformationally sensitive, with the triple-helical form being preferred. When immobilized on a surface, the (Gly-Pro-Nleu)(10)-Gly-Pro-NH(2) sequence stimulated the attachment and growth of corneal epithelial cells and fibroblasts and the migration of epithelial tissue. The peptide sequence KDGEA inhibited cell attachment to the (Gly-Pro-Nleu)(10)-Gly-Pro-NH(2) sequence, suggesting that cell binding to this collagen mimetic involves the alpha2beta1 heterodimer integrin receptor. Interestingly, peptides containing the sequence (GlyNleu-Pro-)(10)-NH(2) did not have cell binding activity. The discovery that triple-helical peptides containing the Gly-Pro-Nleu sequences interact with cells opens up new opportunities in the design of collagen mimetic biomaterials.

Amino Acid Sequence↗
PubMed2000

A membrane-bound Fas decoy receptor expressed by human thymocytes.

Human thymocytes at several stages of maturation express Fas, yet resist apoptosis induction through its ligation. A proximal step in apoptotic signaling through Fas is implicated in this resistance, as these cells undergo normal levels of apoptosis induction after exposure to tumor necrosis factor-alpha. We studied the Fas receptors expressed in human thymocytes to search for mechanisms of receptor-mediated inhibition of Fas signaling in these cells. We describe here a unique, membrane-bound form of Fas receptor that contained a complete extracellular domain of Fas but that lacked a death domain due to alternative splicing of exon 7. This Fas decoy receptor (FDR) was shown to have nearly wild-type ability to bind native human Fas ligand and was expressed predominantly at the plasma membrane. Unlike soluble forms of Fas receptor, FDR dominantly inhibited apoptosis induction by Fas ligand in transfected human embryonic kidney cells. Titration of FDR in Fas-expressing cells suggests that FDR may operate through the formation of mixed receptor complexes. FDR also dominantly inhibited Fas-induced apoptosis in Jurkat T cells. In mixing experiments with wild-type Fas, FDR was capable of inhibiting death signaling at molar ratios less than 0.5, and this relative level of FDR:wild type message was observed in at least some thymocytes tested. The data suggest that Fas signal pathways in primary human cells may be regulated by expression of a membrane-bound decoy receptor, analogous to the regulation of tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-induced apoptosis by decoy receptors.

Alternative Splicing↗
PubMed2000

Genetic diversity at the FMR1 locus in the Indonesian population.

We report an analysis of allelic diversity at short tandem repeat polymorphisms within the fragile XA locus in 1069 male volunteers from twelve Indonesian sub-populations. An odd numbered allele of DXS548 was found at high frequency in all Indonesian populations. Greater allelic diversity was identified at the loci under study than has been previously reported for an Asian population. These differences distinguish the Indonesian population from all previously reported Asian, European and African populations. A high frequency of small premutation alleles, 4/120 (3.3%, 95% CI 0.9-8.3%), was identified in the Moluccan population of Hiri Island.

Alleles↗
PubMed2000

General practitioners: their contact with maternal and child health nurses in postnatal care.

OBJECTIVE: To assess the level of contact of general practitioners (GP) with maternal and child health nurses (MCHN) in postnatal care. METHODOLOGY: A postal survey of 1104 Victorian GP was used, with a response rate of 70%. To account for the clustered sampling frame, hierarchical data analysis techniques were used. RESULTS: Half of the GP (351/710) had no contact with their local MCHN in the previous month; and one in 10 had four or more contacts. Eighty-eight per cent of GP described the contact as helpful. In 56% of cases the MCHN was reported as the usual initiator of the contact. The most common reason for contact concerned the baby's physical problems (42%). After adjusting for the number of women seen for the routine 6-week postnatal review and other GP characteristics, male GP were as likely as female GP to report MCHN contact (odds ratio (OR) = 1.00; 95% confidence interval (CI) = 0.67-1.62). General practitioners aged 31-40 years were more likely to report contact with MCHN than GP aged 51-60 (OR = 0.45; 95% CI = 0.22-0.86) as were GP with the FRACGP qualification (OR = 1.64; 95% CI = 1.21-2.45). CONCLUSIONS: This study provides baseline information on the level of GP contact with MCHN as they provide postnatal care. Although there were GP in Victoria who maintained a level of contact with MCHN, almost half reported no contact in the previous month. Most GP who reported contact with MCHN found it useful. This finding should encourage GP and MCHN coordination to improve continuity and postnatal care outcomes.

Attitude of Health Personnel↗
PubMed2000

A new anthropometric phantom for calibrating in vivo measurements of stable lead in the human leg using x-ray fluorescence.

A new anthropometric phantom has been developed for calibrating in vivo measurements of stable lead deposited in bone using x-ray fluorescence. The phantom reproduces the shape of the mid shaft of the adult human leg and is fabricated using polyurethanes and calcium carbonate to produce materials that exhibit the same density, energy transmission, and calcium content as cortical bone, bone marrow, and muscle. The phantom includes a removable tibia fabricated using simulants for cortical bone and bone marrow to which a precise amount of stable lead has been added to cortical bone. The formulations used in fabricating the new anthropometric phantom are much more uniform in density and composition than the conventional phantom made from Plexiglas cylinders filled with plaster-of-Paris. The energy spectrum from an x-ray fluorescence measurement of the phantom using a 109Cd source is indistinguishable from an in vivo x-ray fluorescence measurement of the human leg, demonstrating that the materials used in the phantom exhibit the same radiological properties as human tissue. Likewise, results from x-ray fluorescence measurements of the phantom exhibit the same positional dependency as the human leg and vary by approximately 36% when, for example, the phantom containing 54 ppm of stable lead in the tibia was rotated by only 15 degrees. The detection limit for a 30 min 109Cd K shell x-ray fluorescence in vivo measurement is approximately 20 ppm determined from a background measurement using the new phantom containing no added lead in the muscle, bone, or bone marrow. The new anthropometric phantom significantly improves in vivo x-ray fluorescence calibration measurements by (1) faithfully reproducing the anatomy of the human leg, (2) having components that exhibit radiological properties similar to that of human tissue, and (3) providing a realistic calibration standard that can be used for in vivo x-ray fluorescence intercomparison measurements.

Adult↗
PubMed2000

A telephone call reminder to improve outpatient attendance in patients referred from the emergency department: a randomised controlled trial.

BACKGROUND: Poor compliance with attendance at outpatient clinic appointments in patients referred from emergency departments (EDs) is a major problem in public hospitals. AIMS: To determine whether the intervention of a telephone call within three days of ED attendance would improve: 1. the proportion of patients making recommended outpatient appointments; and 2. the proportion of patients attending scheduled appointments. To characterise reasons for non-attendance at appointments made by patients referred from the ED. METHODS: A randomised controlled trial was undertaken of 400 patients recommended to make outpatient appointments during attendance at The Royal Melbourne Hospital ED in July-August 1999. INTERVENTION: a telephone call one to three days after attendance to remind the patient about the appointment (and its importance for medical follow-up) if one had been made and to offer to make an appointment if one had not been made. OUTCOME MEASURES: 1. making the recommended appointment; 2. attendance at the scheduled appointment; and 3. reasons for non-attendance at scheduled appointments. RESULTS: The telephone intervention improved attendance at scheduled appointments from 54.4% to 70.7% (p=0.002). The proportion of patients making appointments was not significantly affected. The commonest reasons given for non-attendance were: attended general practitioner (13%), attended private specialist (6.6%), inpatient in hospital at time of appointment (6.6%), too busy or inconvenient (5.3%), claimed to have attended (5.3%) and did not differ by intervention. CONCLUSIONS: A significant improvement in the proportion of patients attending outpatients appointments can be made by a simple reminder telephone call one to three days after attendance at the ED.

Adolescent↗
PubMed2000

Reflex responses induced by tooth unloading.

The reflex response of the masseter muscle to the rapid unloading of a single maxillary incisor tooth was studied. Unloading of a static force of 2 N in the horizontal direction resulted in a short-latency excitation, inhibition, and long-latency excitation of masseter muscle activity occurring at latencies of approximately 13, 20, and 40 ms, respectively, with a corresponding change in bite force occurring slightly later in each case. Following the blocking of periodontal input by the injection of local anesthetic around the stimulated tooth, inhibitory responses were abolished. Therefore, it is concluded that the observed masseteric inhibition was caused by the unloading of periodontal mechanoreceptors and thus that these receptors may contribute to the jaw unloading reflex.

Adult↗
PubMed2000

Retrograde nailing for subtrochanteric femur fractures.

This study reviews the results of subtrochanteric femur fractures treated with a retrograde nail at a level 1 trauma center. Sixteen patients with 17 fractures were followed up until union. The average Injury Severity Score (ISS) was 19, and average knee range of motion was 127 degrees. Four patients required dynamization of their nail, and three healed over a prolonged period of time. Two patients required exchange nailing: one after failure of union after dynamization and one with a broken nail that was revised to an antegrade nailing. The average varus deformity was 5.06 degrees and only 35% of fractures healed in greater than 5 degrees of varus, with an average time to union of 22.4 weeks (range, 6-54 weeks). Antegrade nailing remains the treatment of choice for the vast majority of subtrochanteric femur fractures. However, retrograde femoral nailing may be an effective treatment option for some subtrochanteric fractures in a selected group of patients.

Adolescent↗
PubMed1999

Direct evidence for thymic function in adult humans.

The understanding of human thymic function and evaluation of its contribution to T cell homeostasis are matters of great importance. Here we report the development of a novel assay to quantitate the frequency and diversity of recent thymic emigrants (RTEs) in the peripheral blood of humans. Such cells were defined by the presence of T cell receptor (TCR) rearrangement deletion circles (DCs), episomal byproducts of TCR-beta V(D)J rearrangement. DCs were detected in T cells in the thymus, cord blood, and adult peripheral blood. In the peripheral blood of adults aged 22 to 76 years, their frequency was highest in the CD4(+)CD45RA(+) CD62L(+) subpopulation of naive T cells. TCR DCs were also observed in other subpopulations of peripheral blood T cells, including those with the CD4(+)CD45RO(-)CD62L(+) and CD4(+)CD45RO(+)CD62L(+) phenotypes. RTEs were observed to have more than one Vbeta rearrangement, suggesting that replenishment of the repertoire in the adult is at least oligoclonal. These results demonstrate that the normal adult thymus continues to contribute, even in older individuals, a diverse set of new T cells to the peripheral circulation.

Adult↗