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Biomedical subjects

I Johnson

Publications and source records attributed to I Johnson.

At least 37 records · Page 2Linked to original sources
PubMed2001

An assessment of the feasibility of using image analysis in the oyster embryo-larval development test.

In this study the feasibility of using the latest image capture, processing, and analysis techniques in the oyster embryo-larval development (OEL) test was assessed. This initially involved determining whether the OEL test could be carried out in multiwell plates (which would assist in the application of the image analysis technique), based on data from tests with the reference toxicant zinc and industrial effluents. The study then ascertained which of the 31 image analysis parameters of the Image Pro Plus software used was most appropriate for differentiating between the D larvae and non-D larvae at the end of the test procedure in a manner similar to that of visual observations. On the basis of the zinc reference toxicant and effluent test data derived in this study, the OEL test can be effectively carried out in 24 chamber multiwell plates, which provides the opportunity to count objects with image analysis software. The use of the image analysis parameters area and size (length) in combination resulted in mean control abnormalities and EC50 values in zinc reference toxicant tests which were not significantly different statistically from corresponding values derived using visual observations. Discrimination using the area and length parameters may be improved by the inclusion of other parameters in a suite of measurements which would reduce interference from extraneous material or lighting artefacts. Furthermore, the use of multiwell plates and image analysis can eliminate the variability associated with sub-sampling and inter-operator differences in the counts of D larvae and non-D larvae which is evident with the current visual observation method.

Animals↗
PubMed2001

Inducible change in the behavior of resistance arteries from circulating factor in preeclampsia: an effect specific to myometrial vessels from pregnant women.

OBJECTIVE: It has previously been observed that a circulating factor or factors may be responsible for the changes in vessel behavior that are postulated to underlie the pathogenesis of preeclampsia. We wished to ascertain whether such changes in endothelial function are dependent on the vascular bed under investigation. STUDY DESIGN: Myometrial and infracolic omental vessels resistance vessels were obtained at cesarean delivery or hysterectomy. After incubation with either plasma from women with preeclampsia or plasma from normotensive pregnant women, myographic techniques were used to assess the endothelium-dependent relaxations of these vessels. RESULTS: Incubation of myometrial vessels from normotensive pregnant women with plasma from women with preeclampsia resulted in a significant reduction in endothelium-dependent relaxation, an effect that was independent of the parity of the patients from whom the vessels had been taken. Incubation of omental vessels from normotensive pregnant women and myometrial vessels from nonpregnant women with plasma from women with preeclampsia had no effect on the endothelium-dependent relaxation observed. CONCLUSIONS: This study demonstrates that the inducible changes in resistance vessel behavior are dependent on the tissue bed under investigation and on the pregnancy status of the patient.

Adult↗
PubMed2001

The preliminary characterization of a vasoactive circulating factor(s) in preeclampsia.

OBJECTIVE: The endothelium-dependent behavior of myometrial resistance vessels from women with preeclampsia differs dramatically from that of healthy pregnant women. Similar functional changes may be induced in vessels from healthy pregnant women by incubation with plasma from women with preeclampsia. STUDY DESIGN: Myometrial arterioles, obtained from healthy pregnant women at elective cesarean section, were incubated with plasma from women with preeclampsia or plasma from healthy pregnant women. Myographic techniques were used to study the endothelium-dependent relaxation to bradykinin. The effects of subjecting plasma from women with preeclampsia to heat treatment, charcoal stripping, protein extraction and digestion, and column fractionation on the inducible changes in endothelial function were likewise investigated. RESULTS: Incubation with plasma from women with preeclampsia resulted in a significant reduction in the vessel's endothelium-dependent relaxation, a change that was reversible. This effect was reduced by heat treating and charcoal stripping, maintained within a plasma protein concentrate, and completely removed by protease digestion. The vasoactive component(s) of the plasma had a molecular weight greater than 100 kd. CONCLUSIONS: Plasma of women with preeclampsia alters the endothelium-dependent relaxation of myometrial vessels. Our findings suggest that such alterations are induced by a high-molecular-weight protein/glycoprotein, with possible contributions from a hydrophobic, lipophilic factor.

Adult↗
PubMed2001

Can we predict who will return to a genitourinary clinic?

One hundred and eighty-eight first-time attenders at a genitourinary (GU) clinic were monitored to establish who returned following discharge after treatment. Thirty-six (19%) returned within 2 years with a new infection. The re-attenders did not differ significantly from the rest of the cohort by age, gender or occupation, nor did they differ in their sexual history and psychological variables. Re-attenders were significantly more likely to have consulted their general practitioner (GP) in the 6 months prior to their first clinic attendance.

Female↗
PubMed2000

Alcohol problems in old age: a review of recent epidemiological research.

The subject of alcoholism in late life has received relatively little attention in the literature. This is despite the fact that elderly people are particularly vulnerable to the adverse effects of alcohol. Demographic data predicts that in the first half of the next century there will be an increase in the absolute number of elderly people with alcohol problems. The recognition and treatment of alcohol problems are likely therefore to become more important as this population expands. High rates of comorbidity with physical and psychiatric illness mean that elderly alcoholics are liable to be frequent users of health facilities. Concern has been expressed regarding the impact this trend will have upon health services, particularly the high costs of treatment and institutionalization. Previous researchers in this field have been disadvantaged by a lack of standardized diagnostic criteria and the absence of age-validated screening tools. This paper reviews recent publications relating to the epidemiology of alcohol problems in the elderly and focuses on comparing the prevalence rates of alcohol problems in various clinical settings. Epidemiological research is important as it improves the understanding of the scope and impact of a disease as well as being a vital component during the planning stage for new services. This review highlights some ongoing limitations in recent research.

Age Factors↗
PubMed2000

Dendritic cells enriched from swine thymus co-express CD1, CD2 and major histocompatibility complex class II and actively stimulate alloreactive T lymphocytes.

Initial characterization and partial purification of thymic dendritic cells (DC) from miniature swine were carried out with the ultimate goal of using these cells to induce transplantation tolerance in this preclinical animal model. Immunohistochemical analysis of swine thymic tissue sections has shown DC to be large cells located in the medullary and the cortico-medullary regions as evidenced by the presence of surrounding Hassal bodies. These cells exhibit membrane processes and express the CD1, granulocyte/macrophage (G/M), and major histocompatibility complex (MHC) class II surface antigens, as well as the S100 cytosolic and nuclear markers found in humans to be specific for DC. Dendritic cells were purified from thymi following collagenase treatment, Percoll gradient centrifugation, and adhesion steps to plastic. Cells similar in morphology and phenotype to those described in tissue sections were detected in the lighter density layers of the gradient and represented 0.02% of the starting cell number. Removal of plastic nonadherent cells showed enrichment levels similar to those reported for murine and human DC. Two-colour flow cytometric analysis of purified pig DC identified these cells as MHC class IIhi, CD1+, CD2+, and G/M+. The dendritic nature of these cells was confirmed by their potent ability to stimulate alloreactive T lymphocytes. Modification of porcine thymic DC by transfer of allogeneic MHC genes and reinjection into the DC donor should permit testing of the role of this DC subset in the induction of transplantation tolerance.

Animals↗
PubMed2000

Chemical and physiological characterization of fluo-4 Ca(2+)-indicator dyes.

We have developed fluo-4, a new fluorescent dye for quantifying cellular Ca2+ concentrations in the 100 nM to 1 microM range. Fluo-4 is similar in structure and spectral properties to the widely used fluorescent Ca(2+)-indicator dye, fluo-3, but it has certain advantages over fluo-3. Due to its greater absorption near 488 nm, fluo-4 offers substantially brighter fluorescence emission when used with excitation by argon-ion laser or other sources in conjunction with the standard fluorescein filter set. In vitro, fluo-4 exhibited high fluorescence emission, a high rate of cell permeation, and a large dynamic range for reporting [Ca2+] around a Kd(Ca2+) of 345 nM. We have also developed several Ca(2+)-indicators related to fluo-4 having lower affinities for Ca2+ that are useful in cellular studies requiring quantification of higher [Ca2+]. In a variety of physiological studies of live cells, fluo-4 labeled cells more brightly than did fluo-3, when challenged with procedures designed to elevate calcium levels. Fluo-4 is well suited for photometric and imaging applications that make use of confocal laser scanning microscopy, flow cytometry, or spectrofluorometry, or in fluorometric high-throughput microplate screening assays. Because of its higher fluorescence emission intensity, fluo-4 can be used at lower intracellular concentrations, making its use a less invasive practice.

3T3 Cells↗
PubMed2000

Glutamine and arginine: immunonutrients for improved health.

There is considerable literature demonstrating that specific nutrients can influence immune function in health and disease. This review will examine the literature and the rational for classifying two amino acids, glutamine (gln) and arginine (arg), as "immunonutrients" during infections. An understanding of immune defenses during infections (virus, parasite, bacteria, protozoa) and metabolism of gln and arg by immune cells is necessary to understand how these nutrients can influence specific functions of the immune system. This review focuses on several key clinical studies in immunosuppressed individuals (burn patients, individuals with cancer and HIV infection, and those undergoing surgery or who have experienced major traumas) that have tested the hypothesis that the provision of gln and/or arg is beneficial to immune function and clinical outcome. These clinical studies support the dietary "essentiality" of these two nutrients for improving immune responses in most immunosuppressive states associated with high rates of infection. However, the role of these nutrients in modulating the immune changes that occur with exercise in healthy athletes demands additional experiments.

Arginine↗
PubMed2000

Plasma from women with pre-eclampsia induces an in vitro alteration in the endothelium-dependent behaviour of myometrial resistance arteries.

OBJECTIVE: To compare the in vitro effect of plasma from normal pregnant women and women with pre-eclampsia on the endothelium-dependent behaviour of myometrial resistance arteries from normal pregnant women. DESIGN: An in vitro comparative study. SETTING: Nottingham City Hospital. SAMPLE: Uterine biopsy specimens were obtained from normal pregnant women delivered by elective caesarean section at term. Plasma was collected from nulliparous women with pre-eclampsia (n = 18), and from multiparous normal pregnant women (n = 18), all samples being matched for maternal age and gestation at venepuncture. Pools of plasma from women with pre-eclampsia and normal pregnant women were formed from these samples and were used in all the experiments. METHODS: Myometrial resistance vessels obtained from the uterine biopsies were incubated with normal pregnant plasma, plasma from women with pre-eclampsia, or without plasma. Wire myography was employed to study the effect of plasma on the endothelium-dependent behaviour of these vessels. RESULTS: Incubation of vessels from normal pregnant women with plasma from women with pre-eclampsia resulted in a significant reduction in endothelium-dependent relaxation, compared with vessels incubated either with plasma from normal pregnant women or without plasma. This alteration in endothelial function occurred after an incubation period of one hour and required a threshold concentration for its effect to become established. Removal of the vascular endothelium abolished these changes in vessel behaviour. There were no plasma-induced alterations in the endothelium-independent behaviour of the vascular smooth muscle. CONCLUSIONS: This study supports the hypothesis that plasma from women with pre-eclampsia is capable of altering endothelium-dependent myometrial relaxation in vessels from pregnant women.

Adult↗
PubMed2000

Factors influencing delay in treatment seeking by first-time attenders at a genitourinary clinic.

We examined treatment-seeking behaviours amongst a consecutive sample of 188 first-time attenders at a busy genitourinary (GU) clinic in a general hospital. Participants were interviewed and completed a battery of questionnaires prior to receiving diagnosis or treatment. Delay in treatment seeking was measured in 3 ways: utilization delay, illness behaviour delay and appraisal delay. Appraisal delay and illness behaviour were significantly related, but were unrelated to utilization delay. Substantial delays were reported before seeking treatment, with a median of 30 days elapsing between first noticing symptoms and attending the clinic. Analysis of age groups indicated that the oldest groups--45 and above were likely to delay longest, on all 3 measures of delay.

Adolescent↗
PubMed2000

A randomized trial of winged Vialon cannulae and metal butterfly needles.

The purpose of this parallel randomized study was to evaluate whether subcutaneous infusion sites initiated with winged vialon cannulae would have fewer skin reactions and longer site duration than metal butterfly needles and reduce needlestick injuries to staff. Data were collected on 42 hospice inpatients from the time of insertion of the first needle or cannula to the time of the first replacement of that device. A non-parametric survival plot for time (Kaplan-Meier method) was conducted and the survival time to replacement of the Vialon cannula was found to be longer than the metal butterfly needle. During the study period there were a total of four needlestick injuries to staff from metal butterfly needles. The authors conclude that Vialon cannulae reduce the frequency of site changes and are safer for staff to use because of the reduced risk of needlestick injuries.

Accidents, Occupational↗
PubMed2000

The North Staffordshire Maternity Hospital prospective study of pregnancy-associated depression.

The objective of the study was to establish the frequency of depression during pregnancy and the puerperium, and its relationship to marital disharmony and sociodemographic variables. A prospective longitudinal study was carried out in a district general hospital in the West Midlands, UK. The cohort consisted of 417 women booked for confinement at the hospital. Depression was measured as a proportion of high scores (> 14) on the Edinburgh Postnatal Depression Scale (EPDS) and marital disharmony was determined by the Spanier Dyadic Adjustment Scale. Using recommended cut-offs, 41/417 (9.8%) of the women were depressed during pregnancy and 31/417 (7.4%) were depressed at 3 months postpartum. There was a significant association between antenatal and postnatal depression, seven of the 31 women who were depressed postpartum had also been depressed in the antenatal period. Only five of the 41 women with antenatal depression and eight of the 31 women with postnatal depression were identified by their general practitioners as depressed. Marital disharmony was sequentially associated with depression before and after delivery. We conclude that antenatal depression is more common than generally thought, and that both antenatal and postnatal depression are frequently missed during routine consultation. Pregnancy-associated depression is more common where marital disharmony exists. More widespread use of the EPDS during pregnancy may help to highlight these often unidentified mental health problems.

Adolescent↗
PubMed1999

VEGF via VEGF receptor-1 (Flt-1) mimics preeclamptic plasma in inhibiting uterine blood vessel relaxation in pregnancy: implications in the pathogenesis of preeclampsia.

Preeclampsia is a multisystem disorder characterized by hypertension and proteinuria. There is accumulating evidence that this is a disease of the endothelium, with an as-yet unidentified circulating factor, or factors, causing the observed alteration in vascular function. We previously reported that the function of myometrial vessels is altered on exposure to plasma from women with preeclampsia. Vascular endothelial growth factor (VEGF) is an angiogenic growth factor that acts via two high-affinity receptors (KDR and Flt-1), and its production is increased in preeclampsia. Here we report that VEGF and its Flt-1 receptor may play a pivotal role in the altered vascular function of preeclampsia. Myometrial resistance vessels were obtained at the time of cesarean section. Using the Mulvany wire myograph, the endothelium-dependent behavior of these vessels was studied. Incubation of vessels from pregnant women with VEGF resulted in a reduction of endothelium-dependent relaxation that mimicked the reduction induced by plasma from women with preeclampsia. The altered function that occurred upon exposure of vessels to VEGF or plasma from women with preeclampsia did not occur when plasma was incubated with antibodies to VEGF before vessel incubation. The presence of an anti-KDR receptor antibody had no effect on VEGF response. However, in the presence of an anti-Flt-1 receptor antibody, VEGF or plasma from women with preeclampsia no longer attenuated the endothelium-dependent relaxation (p < 0.05). The changes observed with VEGF and plasma from women with preeclampsia and their subsequent blockade with anti-VEGF antibody and anti-Flt-1 receptor antibody strongly suggest that VEGF acting through the Flt-1 receptor is pivotal in the pathogenesis of this disease.

Adolescent↗