Biomedical subjects

M Jenkins

Publications and source records attributed to M Jenkins.

At least 37 records · Page 2Linked to original sources

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↗

PubMed1999

Fas is expressed early in human thymocyte development but does not transmit an apoptotic signal.

We investigated the expression and function of Fas on human thymocytes prepared from fetal and pediatric tissue specimens and from SCID-hu Thy/Liv grafts. Unlike mouse thymocytes, human thymocytes exhibited a pattern of Fas expression skewed to immature cells, in that the highest expression was seen on double negative thymocytes and on intrathymic T progenitor cells. Fas expression was intermediate on double positive human thymocytes, and low or negative on mature single positive CD4 and CD8 medullary thymocytes. In spite of this relatively abundant surface expression, cross-linking of Fas with agonist mAb was incapable of triggering an apoptotic signal in human thymocytes. Apoptotic signaling was not enhanced by treatment with cycloheximide, nor by restoring a cosignaling milieu by addition of thymic stromal cells. Mouse thymocytes were induced to apoptosis by cross-linked recombinant soluble human Fas ligand both in vitro and in vivo, though human thymocytes were also resistant to this mode of receptor ligation. Membrane-bound Fas ligand also induced apoptotic death in murine thymocytes but not in human thymocytes. Human thymocytes were as sensitive as Jurkat cells, however, to apoptosis induced by TNF-alpha, suggesting that these cells have a signaling defect before activation of the earliest caspases. These data demonstrate a durable and specific resistance of human thymocytes to apoptosis induced through Fas receptor engagement, and reveal significant species-specific differences in the biology of thymocyte-programmed cell death.

Animals↗

PubMed1999

Histopathologic evaluation of an expanded polytetrafluoroethylene-nitinol stent endoprosthesis in canine iliofemoral arteries.

PURPOSE: The authors assess a new ePTFE-nitinol stent for its long-term patency, healing, and properties of endothelialization. MATERIALS AND METHODS: Adult greyhounds (n = 18) underwent bilateral iliofemoral placement of an endoprosthesis (Hemobahn) consisting of a nitinol stent lined with an ultrathin expanded polytetrafluoroethylene (ePTFE) material. Histologic and quantitative morphometric analyses were performed on devices explanted at 2 weeks and 1, 3, 6, and 12 months. The source of endothelialization was examined in four additional devices modified by sealing either the proximal and distal ends or the entire graft with poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), a nonporous laminate to prevent potential transgraft endothelial cell migration. RESULTS: Device patency assessed with both intravascular ultrasound and histologic study showed minimal arterial stenosis, irrespective of implant duration. The neointima at less than 3 months consisted of fibrin and inflammatory infiltrate; at later time points, it was composed of mostly smooth muscle cells. Flow surfaces were more than 75% endothelialized by 3 months, which was nearly complete by 6 months. Modified endoprostheses entirely enveloped with FEP resulted in endothelialization of only the proximal and distal ends; the middle regions showed nonocclusive thrombi. Conversely, devices wrapped proximally and distally showed nearly complete endothelialization. CONCLUSIONS: This ePTFE-nitinol endoprosthesis demonstrated long-term patency at up to 1 year after implantation and showed early and nearly complete endothelialization by 6 months. The design promoted rapid endothelialization of flow surfaces, particularly in the midregion of the device possibly by transgraft migration.

Alloys↗

PubMed1999

Immature human monocyte-derived dendritic cells migrate rapidly to draining lymph nodes after intradermal injection for melanoma immunotherapy.

Injected antigen-loaded immature monocyte-derived dendritic cells (DCs) may be incapable of migrating from skin to draining lymph nodes for antigen presentation. The in vivo migratory capacity of intradermally administered immature monocyte-derived DCs was therefore investigated during a phase I/II clinical trial for metastatic melanoma. DCs cultured from adherent monocytes in the presence of autologous serum, granulocyte-macrophage colony stimulating factor and interleukin-4 were pulsed with antigen and labelled with technetium-99m hexamethylpropylene-amineoxime (99mTc-HMPAO) ex vivo, then injected intradermally. A 99mTc-HMPAO control containing an equivalent amount of radioactivity was injected into the opposite thigh. The pelvis was then imaged with a gamma camera. The DCs were characterized as immature by functional and phenotypic analysis. Labelled DCs travelled to the draining inguinal lymph nodes within 10 min, and the draining lymph nodes were clearly outlined up to 4 h after injection. Free NmTc outlined draining lymph nodes after 10 min but was cleared from the nodes within 1 h. Thus, immature human monocyte-derived DCs migrate rapidly to and remain in draining lymph nodes after intradermal injection for immunotherapy.

Adult↗

PubMed1999

A comparison of the plasma disappearance of iohexol and 99mTc-DTPA for the measurement of glomerular filtration rate (GFR) in diabetes.

BACKGROUND: Changes in glomerular filtration rate (GFR) provide a valuable indicator of the progression of diabetic nephropathy. GFR is most commonly measured by the plasma clearance of radioisotopes, however, use of iohexol, a non-ionic radiocontrast medium, is a recently described alternative and has shown good agreement with inulin clearance. A one-compartment model is used for calculating GFR in most Australian centres but a two-compartment model is more accurate. AIMS: To set up a non-radioisotopic method for assessment of GFR using iohexol, and to compare this with the currently used 99mTc-diethylene-triamine-penta-acetic acid (DTPA) method. Secondly, to compare GFR results using an unmodified one-compartment model with a one-compartment model subjected to the Brochner-Mortensen modification. METHODS: Twenty-one patients with diabetes had assessment of GFR with simultaneous measurements of 99mTc-DTPA and iohexol plasma clearance. Plasma clearance was determined by the slope intercept method and then modified according to the Brochner-Mortensen equation. Plasma iohexol concentrations were determined by capillary electrophoresis. RESULTS: There was no significant difference between iohexol and 99mTc-DTPA derived GFR values, difference 4.3+/-7.7 mL/minute (mean+/-SD). This was despite 99mTc-DTPA protein binding demonstrated in the range of 5-10%. Comparison of GFR results using an unmodified one-compartment model with a Brochner-Mortensen corrected one-compartment model showed higher GFR values with the former, in the range of 20-30% for GFR values > 100 mL/minute. CONCLUSION: Iohexol provides an efficient alternative to radioisotopic methods for serial measurement of GFR in diabetic patients with hyperfiltration, incipient and overt nephropathy. A one-compartment model with its inherent overestimation of GFR should be replaced by the Brochner-Mortensen modified one-compartment model.

Adult↗

PubMed1998

Prevention of peripheral tolerance by a dendritic cell growth factor: flt3 ligand as an adjuvant.

Injections of soluble proteins are poorly immunogenic, and often elicit antigen-specific tolerance. The mechanism of this phenomenon has been an enduring puzzle, but it has been speculated that tolerance induction may be due to antigen presentation by poorly stimulatory, resting B cells, which lack specific immunoglobulin receptors for the protein. In contrast, adjuvants, or infectious agents, which cause the release of proinflammatory cytokines such as tumor necrosis factor alpha and interleukin 1beta in vivo are believed to recruit and activate professional antigen-presenting cells to the site(s) of infection, thereby eliciting immunity. Here we show that administration of Flt3 ligand (FL), a cytokine capable of inducing large numbers of dendritic cells (DCs) in vivo, (a) dramatically enhances the sensitivity of antigen-specific B and T cell responses to systemic injection of a soluble protein, through a CD40-CD40 ligand-dependent mechanism; (b) influences the class of antibody produced; and (c) enables productive immune responses to otherwise tolerogenic protocols. These data support the hypothesis that the delicate balance between immunity and tolerance in vivo is pivotally controlled by DCs, and underscore the potential of FL as a vaccine adjuvant for immunotherapy in infectious disease and other clinical settings.

Adjuvants, Immunologic↗

PubMed1998

Human immunodeficiency virus-1 infection interrupts thymopoiesis and multilineage hematopoiesis in vivo.

It is still uncertain whether multilineage hematopoietic progenitor cells are affected by human immunodeficiency virus-1 (HIV-1) infection in vivo. The SCID-hu Thy/Liv model is permissive of long-term multilineage human hematopoiesis, including T lymphopoiesis. This model was used to investigate the effects of HIV-1 infection on early hematopoietic progenitor function. We found that both lineage-restricted and multilineage hematopoietic progenitors were depleted from grafts infected with either a molecular clone or a primary isolate of HIV-1. Depletion of hematopoietic progenitors (including CD34(+) cells, colony-forming units in methylcellulose, and long-term culture-initiating cells) occurred several days before the onset of thymocyte depletion, indicating that the subsequent rapid decline in thymocyte numbers was due at least in part to loss of thymocyte progenitors. HIV-1 proviral genomes were not detected at high frequency in hematopoietic cells earlier than the intrathymic T-progenitor cell stage, despite the depletion of such cells in infected grafts. Proviral genomes were also not detected in colonies derived from progenitor cells from infected grafts. These data demonstrate that HIV-1 infection interrupts both lineage-restricted and multilineage hematopoiesis in vivo and suggest that depletion of early hematopoietic progenitor cells occurs in the absence of direct viral infection.

Animals↗

PubMed1998

Kinetics of CD4+ T cell repopulation of lymphoid tissues after treatment of HIV-1 infection.

Potent combinations of antiretroviral drugs diminish the turnover of CD4+ T lymphocytes productively infected with HIV-1 and reduce the large pool of virions deposited in lymphoid tissue (LT). To determine to what extent suppression of viral replication and reduction in viral antigens in LT might lead correspondingly to repopulation of the immune system, we characterized CD4+ T lymphocyte populations in LT in which we previously had quantitated viral load and turnover of infected cells before and after treatment. We directly measured by quantitative image analysis changes in total CD4+ T cell counts, the CD45RA+ subset, and fractions of proliferating or apoptotic CD4+ T cells. Compared with normal controls, we documented decreased numbers of CD4+ T cells and increased proliferation and apoptosis. After treatment, proliferation returned to normal levels, and total CD4+ T and CD45RA+ cells increased. We discuss the effects of HIV-1 on this subset based on the concept that renewal mechanisms in the adult are operating at full capacity before infection and cannot meet the additional demand imposed by the loss of productively infected cells. The slow increases in the CD45RA+ CD4+ T cells are consistent with the optimistic conclusions that (i) renewal mechanisms have not been damaged irreparably even at relatively advanced stages of infection and (ii) CD4+ T cell populations can be partially restored by control of active replication without eradication of HIV-1.

Adult↗

PubMed1998

Identification and characterisation of a dense granule-associated protein in Neospora caninum tachyzoites.

Neospora caninum is an apicomplexan parasite which is morphologically and ultrastructurally very similar to Toxoplasma gondii. In order to identify molecules involved in host cell entry and subsequent modification of the parasitophorous vacuole, a polyclonal antiserum directed against N. caninum tachyzoites was raised in a rabbit. Subcellular fractionation of tachyzoites was performed using the non-ionic detergent Triton-X-114. Membrane fractions were analysed by immunoblotting using the polyclonal antiserum. One of the immunoreactive protein bands had a mol. wt of 33,000 and was subsequently named Nc-p33. Affinity-purified anti-Nc-p33 antibodies were used to characterise this polypeptide using SDS-PAGE, isoelectric focusing, Western blot analysis and immuno-EM. Nc-p33 was found in two isolates of N. caninum (NC-1 and Liverpool), but could not be detected in T. gondii tachyzoites. Immunogold EM revealed that Nc-p33 constituted a dense granule-associated protein, and Western blotting demonstrated that Nc-p33 was most likely identical to the recently described antigen NCDG1. Shortly after invasion, this dense granule protein was targeted to the parasitophorous vacuole membrane, and, at later timepoints after infection, was also found on the parasitophorous vacuolar network. This suggested that Nc-p33 could play a functional role in the modification of the parasitophorous vacuole and its membrane.

Animals↗

PubMed1998

Thumb joint flexion. What is normal?

The purpose of this study was to measure the amount of active flexion from a neutral position in normal thumb metacarpophalangeal and interphalangeal joints and compare the results with previously published reports. One hundred and nineteen subjects (238 thumbs) volunteered to have active flexion of the metacarpophalangeal (MP) and interphalangeal (IP) joints of the thumb measured with a computerized Greenleaf goniometer by a certified hand therapist. The mean MP flexion was 59 degrees and IP flexion was 67 degrees. The results of this study suggest that the accepted normal values of thumb flexion should be reconsidered, particularly as a guide for determining impairment.

Adolescent↗

PubMed1998

The naming deficit in early Alzheimer's and vascular dementia.

Patients with early Alzheimer's disease (AD) were compared to normal controls and patients with early vascular dementia (VaD) on their naming errors using the Boston Naming Test (H. Goodglass & E. Kaplan, 1983). All naming errors were classified into three general error categories: visuoperceptual, semantic, and phonemic. Semantic errors were further classified into coordinate errors (responses that belong to the same semantic category as the target words), superordinate errors (responses that belong to a broader semantic category than the target word), and functional-circumlocutory errors (circumlocutions and responses that functionally describe the target word). The findings indicated that AD participants display more overall naming errors than VaD participants, although the pattern of general errors was similar between the patient groups. However, the qualitative difference between the patient groups was observed within the semantic errors because the AD group made more superordinate errors.

Aged↗

PubMed1998

Unreliability of IgE/IgG4 antibody testing as a diagnostic tool in food intolerance.

BACKGROUND: Some clinicians link chronic disease in certain patients to 'food intolerance'. This is currently diagnosed by exclusion dieting, a time-consuming and tedious technique. It has been claimed that IgE/IgG4 antibody testing is a rapid and valid method of determining food intolerance. OBJECTIVE: To determine the test/retest reliability of IgE/IgG4 antibody testing as a diagnostic tool. METHODS: Blinded testing of duplicate blood samples from nine patients with suspected food intolerance was undertaken by tertiary referral centre using the services of a commercial laboratory. The proportions of consistent and inconsistent results for tests of 95 different foods were analysed. RESULTS: Test/retest reliability was low. Even though the study method systematically overestimated kappa, this value never exceeded 0.51, regardless of the statistical model used. All but one patient had a greater number of inconsistent results than had been prespecified as an unacceptable level of disagreement. In one case, 50 out of 95 test results were inconsistent on retest. CONCLUSIONS: We found no evidence that IgE/IgG4 antibody testing as performed by this laboratory is a reliable diagnostic tool.

Allergens↗

PubMed1998

Assessment of pelvic stabilization devices for improved field reproducibility.

The aim of this study was to evaluate the improvement in patient comfort and field positional accuracy provided by a new pelvic stabilization system when delivering multiple field radiotherapy to the pelvis. The Pelvic Cradle (BEHTS Manufacturing, Brisbane, Qld, Australia) is a stabilization device that provides reproducible patient positioning and levelling. Ninety patients were randomized into three groups. The first group was treated using the Pelvic Cradle, the second group was treated using current stabilization practices, and the third group was treated using the Pron Pillo (Chattanooga Pharmacal Company, USA) and current stabilization practices. Port films were assessed for field displacement in the lateral and cranio-caudal directions. A patient survey was used to evaluate the patient's perception of comfort while receiving treatment. When compared to the control group, the pelvic cradle group demonstrated a 48% improvement in the mean lateral deviation from 3.8 mm to 2.0 mm (P < 0.001) and a 36% improvement in the mean cranio-caudal deviation from 3.9 mm to 2.5 mm (P < 0.001). The Pelvic Cradle was found to provide an improved level of field positional accuracy while maintaining patient comfort.

Aged↗