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Biomedical subjects

T Stewart

Publications and source records attributed to T Stewart.

At least 55 records · Page 3Linked to original sources
PubMed1996

Renal cell carcinoma in children: the Detroit experience.

PURPOSE: We analyzed the presentation, treatment and survival of 6 children with renal cell carcinoma. MATERIALS AND METHODS: We retrospectively reviewed the pathological and hospital records of 6 children diagnosed with renal cell carcinoma at Children's Hospital of Michigan (5) and Henry Ford Hospital (1) from 1980 to 1995. RESULTS: The most common presenting complaints were flank pain (50%) and a palpable abdominal mass (50%), while gross hematuria was present in only 1 patient (16%). No patient had the classic triad of flank pain, hematuria and palpable mass. Only 1 patient had localized disease (stage II), while 5 of the 6 presented with stage III or IV disease. While followup is limited, all patients with stage III disease are without evidence of recurrence at a mean 38.5 months and 1 of 2 with stage IV disease is without evidence of disease at 22 months. CONCLUSIONS: Although renal cell carcinoma in childhood often presents at an advanced stage, the prognosis for those with isolated regional lymph node involvement appears to be encouraging.

Adolescent↗
PubMed1995

Incidence of de-novo breast cancer in women chronically immunosuppressed after organ transplantation.

In mice, retrovirus-associated breast cancers are promoted by immune mechanisms, and immunosuppression during the premalignant phase reduces the incidence of breast cancer and prolongs life. If some women likewise have immune promotion of breast cancer, the incidence of breast cancer in patients receiving therapeutic immunosuppression should be lower than that in a comparable cohort of non-immunosuppressed women. We examined the incidence of de-novo breast cancer arising in women receiving immunosuppressive therapy after kidney or heart transplantation, comparing the figures with published rates. In 25,914 immunosuppressed women followed for 1-11 years there were 86 cases of breast cancer compared with 113.8 expected (p = 0.009). Incidence was particularly low in the first transplant year with relative risk 0.49, rising to 0.84 in subsequent years. For all other major cancers the incidence was higher in the immunosuppressed women. If, as in mice, the reduced incidence of breast cancer is a direct effect of immunosuppression, these observations raise the possibility of therapeutic manipulation of specific immune mechanisms that promote tumour growth.

Adult↗
PubMed1995

Spread of bloodborne viruses among Australian prison entrants.

OBJECTIVES: To assess spread of bloodborne viruses among prison entrants in Victoria, Australia. DESIGN: Voluntary confidential testing of all prison entrants for markers of exposure to bloodborne viruses with collection of minimal data on demography and risk factors over 12 months. SETTING: Her Majesty's Prisons, Pentridge and Fairlea, Victoria, Australia. SUBJECTS: 3429 male and 198 female prison entrants (> 99% of all prison entrants); 344 entered prison and were tested more than once. MAIN OUTCOME MEASURES: Prevalence and incidence of antibodies to HIV, hepatitis B, and hepatitis C viruses, and minimal data on risk factors. RESULTS: 1562 (46%) gave a history of use of injected drugs, 1171 (33%) had antibody to hepatitis B core antigen, 1418 (39%) were anti-hepatitis C positive including 914 (64%) of the men who injected drugs, 91 (2.5%) were positive for hepatitis B surface antigen, and 17 (0.47%) were positive for antibody to HIV. Incidence rates for infection with hepatitis B and C virus were 12.6 and 18.3 per 100 person years, respectively; in men who injected drugs and were aged less than 30 years (29% of all prison entrants) these were 21 and 41 per 100 person years. Seroconversion to hepatitis B or C was associated with young age and shorter stay in prison. Only 5% of those who were not immune to hepatitis B reported hepatitis B immunisation. CONCLUSIONS: Hepatitis B and C are spreading rapidly through some populations of injecting drug users in Victoria, particularly among men aged less than 30 years at risk of imprisonment in whom rates of spread are extreme; this group constitutes a sizeable at risk population for spread of HIV. This spread is occurring in a context of integrated harm reduction measures outside prisons for prevention of viral spread but few programmes within or on transition from prisons; it poses an urgent challenge to these programmes.

Adult↗
PubMed1995

Ergonomics standards concerning human-system interaction: visual displays, controls and environmental requirements.

The main purpose of this paper is to explain one of the most important ergonomics standards for computer equipment (ISO 9241), and help the reader to understand how to use it when selecting or designing visual display unit (VDU) equipment and systems. In this paper, we cover general issues, then consider hardware and environmental issues. The software ergonomics and dialogue design issues and corresponding parts will be addressed by Susan Harker in another paper in this special issue.

Journal Article↗
PubMed1995

A vaccine conjugate of 'ISCAR' immunocarrier and peptide epitopes of the E7 cervical cancer-associated protein of human papillomavirus type 16 elicits specific Th1- and Th2-type responses in immunized mice in the absence of oil-based adjuvants.

TraT protein, known as ISCAR (= Immunostimulatory Carrier), is one of a family of integral membrane proteins (Imps) of Escherichia coli representing powerful carrier molecules which when injected into experimental animals generate substantial antibody and T proliferative responses to molecules conjugated to it. We extend these findings to show that ISCAR functions to stimulate Th1- and Th2-type responses, including specific cytotoxic T cells and tumour protection. We report here that by conjugating to ISCAR a 19mer peptide containing linear B epitopes, a T helper (Th) epitope, and a H-2b-restricted T cytotoxic (CTL) epitope of E7 protein of human papillomavirus type 16 (HPV16), and immunizing C57B1/6 (H-2b) mice, we elicited (i) specific IgG2a and IgG1 antibodies; (ii) IL-2 and IL-4 production by specifically recalled lymph node cells in vitro; (iii) cytotoxic T lymphocytes which specifically killed both E7 peptide-pulsed, and whole E7 gene-transfected tumour target cells; and (iv) in vivo protection against an E7 gene-transfected tumour cell inoculum. These findings have implications for the design of vaccines to stimulate immune responses to endogenously processed target antigens (e.g. tumour-associated antigens) without the unwanted side effects of oil-based adjuvants. In addition they support the case for a E7-targeted therapeutic vaccine for HPV-associated human cervical cancer.

Adjuvants, Immunologic↗
PubMed1995

The incidence, numbers and types of Listeria monocytogenes isolated from farm bulk tank milks.

Bulk tank milk from 160 producers was tested for Listeria monocytogenes at three monthly intervals over 1 year. Twenty-five producers were positive, most on a single occasion, only seven were positive on three or more of the four samplings. Listeria monocytogenes numbers were low, usually < 1 ml-1, the highest was 35 ml-1. All isolates were serotype 1, the use of multilocus enzyme electrophoresis on representative isolates gave nine different electrophoretic types, two have been associated with listeriosis in humans or animals, a further two had only been isolated from one other source (silage or faeces), while the majority (5) were unique to milk.

Animals↗
PubMed1995

Factors influencing cardiopulmonary effects of inhaled nitric oxide in acute respiratory failure.

The aim of this prospective study was to determine factors influencing effects of inhaled nitric oxide (NO) on the pulmonary circulation and on gas exchange in critically ill patients with acute lung injury. Twenty-one hypoxemic patients with acute respiratory failure (PaO2 = 127 +/- 69 mm Hg during intermittent positive pressure ventilation, FiO2 = 1), were mechanically ventilated with 2 ppm NO and pure oxygen. The effect of positive end-expiratory pressure (PEEP) on alveolar recruitment was assessed on an anatomic basis using a high-resolution and spiral thoracic computed tomographic (CT) scan. Four conditions were studied in random order: zero end-expiratory pressure (ZEEP), ZEEP + 2 ppm NO, 10 cm H2O PEEP, 10 cm H2O PEEP + 2 ppm NO. During ZEEP and PEEP, NO significantly decreased pulmonary vascular resistance index (PVRI), mean pulmonary arterial pressure (MPAP), true pulmonary shunt (Qs/QT), and alveolar dead space (VDA/VT) and significantly increased PaO2 (p < 0.01). During ZEEP, NO-induced decreases in PVRI (delta PVRI) and MPAP (delta MPAP) were significantly correlated to baseline PVRI and MPAP (delta PVRI = -0.5 PVRI + 125, r = 0.97, p < 0.01 and delta MPAP = -0.28 MPAP + 4.8, r = 0.69, p < 0.05). These changes were not potentiated by PEEP-induced alveolar recruitment. The NO-induced increase in PaO2 (delta PaO2) was not significantly correlated with baseline PaO2 but was correlated with baseline PVRI (delta PaO2 = 0.11 PVRI + 30, r = 0.67, p < 0.05). In patients in whom PEEP was associated with alveolar recruitment, NO increased PaO2 by 66 +/- 24 mm Hg during ZEEP and by 104 +/- 26 mm Hg during PEEP (p < 0.01). In patients in whom PEEP did not induce alveolar recruitment, the NO-induced increase in PaO2 was similar during ZEEP and PEEP conditions (+70 +/- 15 mm Hg versus +76 +/- 12 mm Hg, NS). In patients with adult respiratory distress syndrome, factors determining NO-induced improvement in arterial oxygenation and pulmonary vascular effects are PEEP-induced alveolar recruitment and the baseline level of pulmonary vascular resistance.

Administration, Inhalation↗
PubMed1995

Doctors' holding power in practice: section 5(2) of the Mental Health Act 1983.

Section 5(2) of the Mental Health Act 1983 (England and Wales) is a commonly used short term power of detention often implemented by junior medical staff, which has no statutory right of appeal. There is little published analysis of its use in clinical practice. A detailed case note study of its use in a psychiatric service with a large catchment area is presented. Fifty-seven per cent of the patients detained under s.5(2) were female. Affective psychosis was over-represented in detained females, while schizophrenia and paranoid states were over-represented in males. Eight per cent of s.5(2) detentions were initiated via the nurses' holding power, s.5(4). None of these patients were subsequently regraded to s.2 or 3, which may be accounted for by the finding that personality disorder and alcohol dependence were more commonly diagnosed in this subgroup. Of s.5(2) detainees, none of those with a non-psychotic disorder were regraded to s.2 or 3. Three patients had not accepted in-patient admission prior to implementation of s.5(2). Moreover, 38 per cent of all s.5(2) detentions took place within 24 hours of admission. Patients with a psychotic disorder were more likely to be detained within 24 hours of admission. Doubts regarding the validity of consent to voluntary admission in these patients are raised.

Commitment of Persons with Psychiatric Disorders↗
PubMed1995

Contact pressure prediction in total knee joint replacements. Part 2: Application to the design of total knee joint replacements.

The general elasticity contact theory for elliptical geometry developed in Part 1 (1) has been applied to the design of current total knee joint replacements. A two-step curve-fitting technique using cubic spline interpolation routines has been adopted to represent the full elasticity solutions. The curve fit results of the maximum contact pressure have been compared with the full elasticity solution for a specified elliptical geometry and different polyethylene thicknesses and good agreement has been demonstrated. The computing time required by the curve-fitting technique is very small compared with the full elasticity solution and therefore can readily be applied to the design of knee joint replacements. Furthermore, reasonable agreement has also been found for the contact area for a typical knee joint design between the present theoretical prediction and the experimental measurement using pressure-sensitive film. Predictions of the maximum contact pressure have been made for an existing knee joint replacement in order to illustrate the present analysis in the design cycle. It has been shown that the effect of the thickness of ultra high molecular weight polyethylene is relatively small on contact stress predictions provided a sufficiently large value is chosen. On the other hand, the effect of conformity has a much greater influence on the contact stress distribution, particularly in the direction of the smaller principal radius.

Elasticity↗
PubMed1995

Experimental and theoretical study of the contact mechanics of five total knee joint replacements.

The tibio-femoral contact area in five current popular total knee joint replacements has been measured using pressure-sensitive film under a normal load of 2.5 kN and at several angles of flexion. The corresponding maximum contact pressure has been estimated from the measured contact areas and found to exceed the point at which plastic deformation is expected in the ultra-high molecular weight polyethylene (UHMWPE) component, particularly at flexion angles near 90 degrees. The measured contact area and the estimated maximum contact stress have been found to be similar in magnitude for all of the five knee joint replacements tested. A significant difference, however, has been found in maximum contact pressure predicted from linear elasticity analysis for the different knee joints. This indicates that varying amounts of plastic deformation occurred in the polyethylene component in the different knee designs. It is important to know the extent of damage as knees with large amounts of plastic deformation are more likely to suffer low cycle fatigue failure. It is therefore concluded that the measurement of contact areas alone can be misleading in the design of and deformation in total knee joint replacements. It is important to modify geometries to reduce the maximum contact stress as predicted from the linear elasticity analysis, to below the linear elastic limit of the plastic component.

Anthropometry↗
PubMed1994

Anti-immunoglobulin E treatment decreases worm burden and egg production in Schistosoma mansoni-infected normal and interferon gamma knockout mice.

The immunoglobulin E (IgE) response is generally considered an essential component of the host defense against parasitic helminths such as Schistosoma mansoni. In contrast, work on antischistosome vaccines suggests that interferon gamma (IFN-gamma) is the critical immune mediator for vaccine-induced immunity to the parasite. In this study, the total IgE response to a primary S. mansoni infection was suppressed by anti-IgE treatment in both normal mice and in mice with defective IFN genes (gene knockout [GKO]). Reduction of the IgE response resulted in decreased worm burden and a decrease in the number of eggs produced per worm in both normal and GKO mice. Whereas anti-IgE treatment also resulted in reduced hepatosplenomegaly, granulomas around existing schistosome eggs showed normal cellularity. Serum interleukin 4 levels fell in response to the reduction in serum IgE as well. The data suggest that IgE plays a detrimental, rather than beneficial, role for the host in schistosomiasis. Furthermore, the absence of IFN-gamma was found to be of little consequence to the host-response to adults or eggs in a primary schistosome infection.

Animals↗
PubMed1994

Observations on the adrenocortical structure of the female brush-tailed possum (Trichosurus vulpecula) and locations of cell division.

Twenty mature female possums (Trichosurus vulpecula) were captured at the Harry Waring Marsupial Reserve, some 30 km south of Perth in Western Australia, and injected simultaneously with tritiated thymidine in order to label dividing cells within the adrenal gland. The conservation status of the possum precluded killing all animals and adrenal glands were removed and examined histologically and autoradiographically in four experimental groups, timed for 1 hr, 1 week, and 2, 3, and 7 weeks following the injection. In two of the groups [untreated and FSH-1 (injected with an urogonadotrophin)] the left gland was obtained by unilateral adrenalectomy, whereas in the other two groups (ACTH and FSH-2, of pituitary origin) the animals were killed at the specified intervals. The precise location of labeled adrenocytes with time was measured in autoradiogrammes of adrenal sections. The labeled cells were counted and the distance from the outer connective-tissue capsule was measured with a MOP-Videoplan, calibrated for distance. The widths of the various cortical zones and the medulla were also estimated. The study focused primarily on the "Special Zone" (SZ) which is unique to the adrenals of the mature female possum. The only effect of hormonal treatments discerned was a slight hypertrophic effect of porcine FSH on the size of the SZ. Labeled cells indicative of cell division were found randomly distributed throughout the SZ, as well as in the cortex and occasionally, the medulla. Time series analysis gave no evidence of the progressive centripetal movement of cells within the SZ and our data are thus not consistent with the "Cell Migration Theory" concerning the differentiation of adrenocytes and accord instead with the "Zonal Theory" proposed to account for the maintenance of the classical zones in the eutherian adrenal cortex.

Adrenal Cortex↗
PubMed1994

Inhaled nitric oxide reverses the increase in pulmonary vascular resistance induced by permissive hypercapnia in patients with acute respiratory distress syndrome.

BACKGROUND: The aim of this prospective study was to determine if inhaled nitric oxide (NO) would reverse the increase in pulmonary arterial pressures and in pulmonary vascular resistance induced by acute permissive hypercapnia in patients with acute respiratory distress syndrome. METHODS: In 11 critically ill patients (mean age 59 +/- 22 yr) with acute respiratory distress syndrome (Murray Score > or = 2.5), the lungs were mechanically ventilated with NO 2 ppm during both normocapnic and hypercapnic conditions. Four phases were studied: normocapnia (arterial carbon dioxide tension 38 +/- 6 mmHg, tidal volume (655 +/- 132 ml); normocapnia plus inhaled NO 2 ppm; hypercapnia (arterial carbon dioxide tension 65 +/- 15 mmHg, tidal volume 330 +/- 93 ml); and hypercapnia plus inhaled NO 2 ppm. Continuous recordings were made of heart rate, arterial pressure, pulmonary artery pressure, tracheal pressure, and tidal volume (by pneumotachograph). At the end of each condition, arterial pressure, pulmonary artery pressure, cardiac filling pressures, and cardiac output were measured. Simultaneous arterial and mixed venous blood samples were obtained to measure arterial oxygen tension, arterial carbon dioxide tension, mixed venous oxygen tension, arterial hemoglobin oxygen saturation, mixed venous hemoglobin oxygen saturation, pH, and blood hemoglobin and methemoglobin concentrations (by hemoximeter). In addition, plasma concentrations of catecholamines were measured with a radioenzymatic assay. In 5 patients, end-tidal carbon dioxide tension was measured with a nonaspirative infrared capnometer. Calculations were made of pulmonary vascular resistance index, systemic vascular resistance index, true pulmonary shunt, and alveolar dead space. RESULTS: During hypercapnia, NO decreased pulmonary vascular resistance index from 525 +/- 223 to 393 +/- 142 dyn.s.cm-5.m-2 (P < 0.01), a value similar to that measured in normocapnic conditions (391 +/- 122 dyn.s.cm-5.m-2). It also reduced mean pulmonary artery pressure from 40 +/- 9 to 35 +/- 8 mmHg (P < 0.01). NO increased arterial oxygen tension (inspired oxygen fraction 1) from 184 +/- 67 to 270 +/- 87 mmHg during normocapnia and from 189 +/- 73 to 258 +/- 101 mmHg during hypercapnia (P < 0.01). NO decreased true pulmonary shunt during normocapnia (from 34 +/- 3% to 28 +/- 4%, P < 0.001) but had no significant effect on it during hypercapnia (39 +/- 7% vs. 38 +/- 8.5%). In five patients, NO resulted in a decrease in alveolar dead space from 34 +/- 7% to 28 +/- 10% in normocapnic conditions and from 30 +/- 9% to 22 +/- 10% in hypercapnic conditions (P < 0.05). CONCLUSIONS: Inhaled NO completely reversed the increase in pulmonary vascular resistance index induced by acute permissive hypercapnia. It only partially reduced the pulmonary hypertension induced by acute permissive hypercapnia, probably because the flow component of the increase in pulmonary pressure (i.e., the increase in cardiac output) was not reduced by inhaled NO. A significant increase in arterial oxygenation after NO administration was observed during normocapnic and hypercapnic conditions. A ventilation strategy combining permissive hypercapnia and inhaled NO may reduce the potentially deleterious effects that permissive hypercapnia alone has on lung parenchyma and pulmonary circulation.

Administration, Inhalation↗
PubMed1994

Legislation for school entry immunisation certificates in Victoria.

In 1982 the National Health and Medical Research Council recommended that every state introduce legislation requiring immunisation certificates at school entry. Victoria was the first state to enact such legislation. This paper explores the process and difficulties encountered in achieving this legal requirement, describes the requirements under the legislation as it was finally introduced, and examines the early data available to the state health department regarding its implementation. Compliance with the legislation and immunisation status of children enrolling in government primary schools were ascertained from mid-year census data. In 1992 almost 90 per cent of children complied with the legislation, but because 10.2 per cent of children did not present a certificate it was possible to estimate only the lower limit of statewide coverage at 85 per cent against the prescribed diseases. School entry immunisation legislation may provide an important safety net to identify children with incomplete immunisation. However, the effectiveness of the legislation in Victoria remains unproven, and the requirements of the legislation are demanding for parents, local councils, and schools. The failure to document immunisation status in over 10 per cent of children indicates that further efforts to increase compliance are needed. This will require information on the vaccination status of those without certificates and the reasons they have not complied. The impact of the legislation needs further evaluation, although it may be years before its effectiveness can be gauged. Its effectiveness may depend upon enforcement of the requirement to exclude unimmunised children in disease outbreaks.

Child↗
PubMed1994

Surveillance for sexually transmissible diseases in Victoria, 1983 to 1992.

Surveillance systems have been developed in Victoria to determine trends in sexually transmissible diseases (STDs). Notifications to the Health Department (including laboratory notification since May 1990) have been supplemented by data about strains of Neisseria gonorrhoeae and cultures for Chlamydia trachomatis processed by the Microbiological Diagnostic Unit, enhanced laboratory surveillance of syphilis, and data on genital herpes and genital warts from the Melbourne Sexual Health Centre. During the period under review the incidence of gonorrhoea declined, rapidly at first, and then more slowly. For women, this trend has continued, while gonorrhoea acquired abroad by men has become relatively more important. Since 1988, gonorrhoea in homosexual men has increased, and rectal isolates have increased concurrently, raising concerns about HIV risk behaviour. Cases of syphilis are likely to be ascertained through STD, antenatal and refugee screening, rather than because of symptoms or contact tracing. Chlamydia is a the most common notifiable STD, despite underreporting and underdiagnosis. In 1991, 832 cases were notified, increasing to 1377 in 1992. In 1992, of the 73 cases (65 per cent of notifications) where the doctor identified a risk, 15 per cent was attributed to homosexual contact, and 27.4 per cent to heterosexual exposure. Limitations in the data include inadequate standard case definitions for many STDs, changes in the statutory requirement for notifications in 1990, underreporting, changes in diagnostic and screening patterns, and lack of detailed demographic data. Education of general practitioners is needed to improve diagnosis and notification of chlamydia.

Adult↗
PubMed1994

Comparison of litter adjustment factors in Yorkshire and Landrace data.

National Swine Improvement Federation (NSIF) adjustment factors presently used to standardize litter data for age at 21 d, number born alive (NBA), 21-d litter weight, and number after transfer (NAT) were evaluated using 104,884 litters in 1,348 Yorkshire herds and 20,370 litters in 197 Landrace herds. In addition, adjustment factors for number weaned were calculated for standardization of this trait. Number weaned is adjusted for parity and NAT. The mixed-model least squares, maximum likelihood computer program described by Harvey was used in the analyses. Yorkshire and Landrace data were combined to test for breed effects and interactions involving breed. Breed interactions were different (P < .05). Therefore, breed-specific adjustment factors were calculated for Yorkshire and Landrace data sets. Also, adjustment factors were calculated for combined data that might be appropriate to use for breeds without specific adjustments available. Parity adjustment factors for NBA and 21-d litter weight were different (P < .05) from current NSIF recommendations, as was the NAT adjustment for 21-d litter weight. The age-at-weaning multiplicative factors were not different (P > .05) from current NSIF values. However, in all three data sets, the intercepts and linear coefficients of the quadratic regression for age at weaning were different (P < .05) from NSIF's. A Student-Newman-Keuls (SNK) test was used to evaluate the NSIF groupings of parity and number after transfer.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗