PubMed Health⌕ Search

Biomedical subjects

C M Bennett

Publications and source records attributed to C M Bennett.

At least 19 recordsLinked to original sources
PubMed2006

Impact of the 1998 Gobi dust event on hospital admissions in the Lower Fraser Valley, British Columbia.

The adverse public health impacts of anthropogenically derived particulate matter have been well documented, with measurable increases in both morbidity and mortality rates associated with high particulate matter pollution events. Most current research has focussed on the health impacts of anthropogenically derived particulate matter, and there is a distinct scarcity of literature that examines the role of naturally derived particulate matter and adverse health impacts in the urban context. This study of a Gobi desert dust event in the Greater Vancouver region of British Columbia, Canada, in spring of 1998 provided a unique opportunity to identify the adverse health effects related to naturally derived particulate matter in a large urban setting. Respiratory and cardiac hospitalizations were examined for a three-year period (January 1997 to December 1999), with the Gobi dust event occurring in late April 1998. A meteorological analogue was identified for spring 1997 in order to identify the public health impacts associated with anthropogenically derived particulate matter and those impacts associated with the presence of the Gobi desert dust. Results indicate that this Gobi dust event was not associated with an excess of hospitalizations in the Greater Vancouver region. Peak particulate matter concentrations of Gobi desert dust in the airshed were only associated with an additional one or two hospitalizations per 100,000 population for respiratory and cardiac illnesses, and these increases were not distinguishable from the 'normal' variability in hospitalization rates. Despite high particulate matter concentrations, fine particle size, presence of heavy metals in the dust and extended exposure periods, it appears that the Gobi desert dust event was not associated with significant risk to public health in Greater Vancouver, British Columbia. Therefore it is concluded that naturally derived particulate matter is more benign than particulate matter of anthropogenic origin, and thus poses a low risk to health for the general public.

Air Pollutants↗
PubMed2006

Rituximab for adolescents with haemophilia and high titre inhibitors.

Neutralizing alloantibodies (inhibitors) to factor VIII or factor IX develop in approximately 25% of patients with haemophilia A and <3% of patients with haemophilia B treated with factor concentrate. Patients with high titre inhibitors, in whom immune tolerance therapy fails, have few treatment options. Targeted anti-B-cell therapy with rituximab (chimeric anti-CD20) has been useful in several antibody-mediated autoimmune states. Case reports of rituximab treatment in small numbers of haemophilia patients with inhibitors have been inconclusive. We describe three adolescent patients with severe haemophilia and inhibitors treated with four weekly doses of rituximab, 375 mg m(-2). Treatment with rituximab was effective in reducing the inhibitor titre in two of three patients. Rituximab may be beneficial for patients with severe haemophilia and inhibitors in whom standard therapies have failed, but larger prospective studies are required to determine safety, efficacy and predictors of success.

Adolescent↗
PubMed2003

Is restricting tobacco sales the answer to adolescent smoking?

Enforcement of legislation restricting retail access to tobacco is increasingly relied on to reduce adolescent smoking rates. In 1996, health authorities in the Northern Sydney Health Area began monitoring tobacco retailer compliance (PROOF program) with staged purchase attempts by adolescents below the legal age (18 years). Repeat cross-sectional surveys before (1995) and after (2000) the introduction of PROOF monitored changes in adolescent smoking behaviour. Students aged 12 to 17 years from 11 Northern Sydney metropolitan public secondary schools were surveyed for self-reported smoking and tobacco purchasing behavior in 1995 (n = 5,206) and 2000 (n = 4,120). Between 1996 and 2000, 545 retailer compliance checks found 34% unlawfully sold cigarettes to minors and 28% of these repeated the offence. Nine prosecutions resulted. Modelling revealed a significant association between the intervention and never having smoked (adjusted OR = 1.16, 95% CI = 1.01-1.33) although there was no significant association with being a current smoker. The odds of being a smoker were greater for students from coeducational schools, with this effect being modified by gender. There was no reduction in adolescent smoking with active enforcement of tobacco access laws despite an apparent increase in students who reported never to have smoked.

Adolescent↗
PubMed2003

Fresh garlic: a possible vehicle for Salmonella Virchow.

A sustained increase in Salmonella enterica serovar Virchow notifications in South Eastern Australia between September 1997 and May 1998 instigated a case-control study and environmental investigations. Cases were defined as having locally acquired culture-confirmed S. Virchow phage-type 8 infection and diarrhoeal disease. Matched controls were selected by progressive digit dialling based on cases' telephone numbers. An exposure and food history questionnaire was administered by telephone. Phage typing and pulse field gel electrophoresis were performed on case and environmental isolates. Thirty-two notifications of S. Virchow infection met the case definition, 37% reported bloody diarrhoea and S. Virchow was isolated from blood in 13% of cases. Twelve patients were admitted to hospital and one died. Fresh garlic (OR 4.1, 95% CI 1.3-12.8) and semi-dried tomatoes (OR 12.6, 95% CI 1.5-103.1) were associated with these cases. The associations remained significant after adjusting for sex and age. S. Virchow (PT 8) was cultured from two brands of semi-dried tomatoes associated with cases in two different states. We provide sufficient evidence for semi-dried tomatoes and fresh garlic to be considered as potential risk foods in future Salmonella outbreak investigations.

Adolescent↗
PubMed2001

Myelopoiesis in the zebrafish, Danio rerio.

Genome-wide chemical mutagenesis screens in the zebrafish (Danio rerio) have led to the identification of novel genes affecting vertebrate erythropoiesis. In determining if this approach could also be used to clarify the molecular genetics of myelopoiesis, it was found that the developmental hierarchy of myeloid precursors in the zebrafish kidney is similar to that in human bone marrow. Zebrafish neutrophils resembled human neutrophils, possessing segmented nuclei and myeloperoxidase-positive cytoplasmic granules. The zebrafish homologue of the human myeloperoxidase (MPO) gene, which is specific to cells of the neutrophil lineage, was cloned and used to synthesize antisense RNA probes for in situ hybridization analyses of zebrafish embryos. Granulocytic cells expressing zebrafish mpo were first evident at 18 hours after fertilization (hpf) in the posterior intermediate cell mass (ICM) and on the anterior yolk sac by 20 hpf. By 24 hpf, mpo-expressing cells were observed along the ICM and within the developing vascular system. Thus, the mpo gene should provide a useful molecular probe for identifying zebrafish mutants with defects in granulopoiesis. The expression of zebrafish homologues was also examined in 2 other mammalian hematopoietic genes, Pu.1, which appears to initiate a commitment step in normal mammalian myeloid development, and L-Plastin, a gene expressed by human monocytes and macrophages. The results demonstrate a high level of conservation of the spatio-temporal expression patterns of these genes between zebrafish and mammals. The morphologic and molecular genetic evidence presented here supports the zebrafish as an informative model system for the study of normal and aberrant human myelopoiesis. (Blood. 2001;98:643-651)

Amino Acid Sequence↗
PubMed2000

Hypoglycaemia induced by exogenous insulin--'human' and animal insulin compared.

AIMS: A systematic review of the literature was carried out to examine whether published evidence suggests a difference in the frequency and awareness of hypoglycaemia induced by 'human' and animal insulin. METHODS: The review identified randomized controlled trials and studies of other designs including observational comparisons, case series and case reports in which the use of 'human' insulin was compared to animal insulin in people with diabetes. These were identified from bibliographic databases and hand-searches of key journals. The main outcome measures were frequency, severity, awareness and symptoms of insulin induced hypoglycaemia. RESULTS: Fifty-two randomized controlled trials, 37 of double-blind design, were identified which included one or more of the relevant outcome measures. Of these, 21 specifically investigated hypoglycaemic frequency and awareness as primary outcomes (six in people with previously reported reduced hypoglycaemic awareness). The remainder of the identified trials reported hypoglycaemic outcomes as a secondary or incidental outcome during comparative investigations of efficacy or immunogenicity. Seven of the double-blind studies reported differences in frequency of hypoglycaemia or awareness of symptoms, although none of the studies which selected subjects on the basis of previously reported impaired awareness demonstrated significant differences between insulin species. Four of the unblinded trials reported differences in hypoglycaemia. This reached statistical significance in two of the studies. A further 56 studies of other designs and case reports were considered. In addition to the 10 case reports describing individuals with impaired hypoglycaemic awareness, nine studies reported differences in the incidence and manifestation of hypoglycaemia during 'human' insulin treatment. Notably, none of the four population time trend studies found any relationship between the increasing use of 'human' insulin and hospital admission for hypoglycaemia or unexplained death among those with diabetes. The largest case series could find no support for the hypothesis that an influence of treatment with 'human' insulin on hypoglycaemia had contributed to any of the 50 deaths investigated. When all types of studies considered are ranked in order of rigour (according to the accepted 'hierarchy of evidence'), it is the least rigorous which lend most support to the notion that treatment with 'human' insulin has an effect on the frequency, severity or symptoms of hypoglycaemia. CONCLUSIONS: Evidence does not support the contention that treatment with 'human' insulin per se affects the frequency, severity or symptoms of hypoglycaemia. However, a number of studies, mainly those of less rigorous design, describe an effect when people are transferred from animal insulin to 'human' insulin. It is not possible to state how common this is or whether the phenomenon is specific to 'human' insulin or an effect resulting from stricter glycaemic control (perhaps compounded, in some cases, by neurological complications in long-standing diabetes). This remaining uncertainty makes it essential that insulin from animal sources continues to be available so that clinicians and patients may retain this choice of treatment.

Animals↗
PubMed1999

Respiratory symptoms and duration of residence in immigrant teenagers living in Melbourne, Australia.

OBJECTIVE: Examination of the relation between respiratory symptoms and time since arrival in Australia in immigrant teenagers living in Melbourne. DESIGN: Two stage, stratified, cross sectional survey. SETTING: High schools (n = 51). SUBJECTS: 9794 people aged 13-19 years. MAIN OUTCOME MEASURES: Prevalence of wheeze during a 12 month period, region of birth, duration of residence in Australia. RESULTS: The estimated population 12 month period prevalence of wheeze was 18.9% (95% confidence interval (CI), 18.0 to 19.9). In subjects born outside Australia, residence for five to nine years in Australia was associated with a 2.1-fold (CI, 1.1 to 4.0) increase in the odds of self reported wheeze; after 10-14 years, this risk increased 3.4-fold (CI, 1.8 to 6.7). There was no difference in severity of wheeze, measured by reported frequency of attacks, between Australian born and non-Australian born subjects. CONCLUSIONS: The notion of a continued secular increase in the prevalence of wheezing is not supported. There is a time dose effect on the prevalence of symptoms in subjects born outside Australia and now living in Melbourne, which is independent of age and country of birth.

Adolescent↗
PubMed1998

Prevalence of tuberculosis infection in Melbourne secondary school students.

OBJECTIVE: To estimate the prevalence of asymptomatic Mycobacterium tuberculosis infection in Melbourne secondary school students. DESIGN: Cross-sectional Mantoux testing of a partly random and partly targeted sample of secondary school students, designed to enable estimation of prevalence by region of birth. SETTING: Fifty-one State and Catholic secondary schools in metropolitan Melbourne during 1995. PARTICIPANTS: Australian and overseas-born students in Years 9 and 10. OUTCOME MEASURES: Proportions of students with positive Mantoux reactions (defined as induration at 48 hours of > or = 5 mm with a history of recent exposure; > or = 10 mm and no prior BCG vaccination; > or = 15 mm and prior BCG vaccination). RESULTS: Of 2586 students potentially eligible for testing, evaluable results were obtained from 1274 (49%). The overall prevalence of infection for Melbourne students in Years 9 and 10 was 2.5% (95% CI, 1.1-3.9%). Main predictors of a positive test were birth overseas and number of years residing overseas. Prevalence varied considerably by region of birth, and was very low in students born in Australia (0.7%), "other developed countries" (0.7%), and Southern Europe (0). The highest rates were observed in students born in Indochina (15.9%), other countries in South East Asia (10.2%), and Eastern Europe (10.2%). CONCLUSIONS: The risk of a young person becoming infected with M. tuberculosis while living in Melbourne is very low. Our results do not indicate a need for the reintroduction of mass screening in Victorian schools. If targeted screening were to be considered, the group most likely to benefit would be recently arrived migrants from Indochina.

Adjuvants, Immunologic↗
PubMed1997

Walking to school and traffic exposure in Australian children.

Daily patterns of pedestrian activity in young children have important health implications, primarily because of the risk of road traffic injury, but also because they may reflect the commencement of exercise habits with long-term consequences. A cross-sectional survey in two Australian cities, Melbourne and Perth, aimed to collect, by parent self-administered questionnaire, population-based data on modes of travel, numbers of street crossings (both accompanied and unaccompanied by an adult), and sociodemographic factors for six- and nine-year-old children. Results indicate that 35 per cent (95 per cent confidence interval (CI) 31 to 39 per cent) and 31 per cent (CI 28 to 34 per cent) walk to school in Melbourne and Perth respectively, while over 60 per cent are driven to school by car, with very small proportions riding bicycles or taking public transport. A higher level of walking was associated with lower levels of several indicators of socioeconomic status. Logistic regression analysis showed that the strongest predictor of walking activity was school type (government versus independent), and after adjusting for this, lesser car ownership, non-English-speaking background and lower occupational category were associated with walking to school, while a different set of predictors--age, sex and maternal education--was associated with the unaccompanied crossing of streets. There was little difference in overall walking levels between boys and girls, but boys were significantly more likely to cross streets unaccompanied (adjusted odds ratio 1.41, CI 1.14 to 1.72), providing a partial explanation of documented sex differences in injury rates.

Accidents, Traffic↗
PubMed1993

Australian Rules football injuries in children and adolescents.

OBJECTIVE: To ascertain the incidence, severity, risk factors, and outcomes of injuries in children and adolescents playing Australian Rules football. DESIGN SETTING AND SUBJECTS: A prospective cohort study of football injuries in children and adolescents playing community football. We studied a stratified random sample of 54 teams and clinics (18 under-15 teams, 18 under-10 teams and 18 Vickick clinics for children under 10 years) from the Melbourne metropolitan area. Football exposure, injuries and associated risk factors were recorded for 1253 players during the 1992 football season. RESULTS: Vickick, a modified form of the game, had the lowest rates of injury for all levels of injury severity, with an overall rate of 3.49 injuries per 1000 player-hours. The rate in the under-10 age group was 2.4 times higher (95% confidence interval [CI], 1.5-3.8) than that in Vickick, and the under-15 rate was 1.2 times (95% CI, 0.9-1.6) that of the under-10s. The under-15 age group had significantly more injuries that led to use of health services than the under-10 and Vickick groups, with rates of 3.93 (95% CI, 2.9-4.9), 0.64 (95% CI, 0.2-1.4), and 0.33 (95% CI, 0.1-0.8) injuries per 1000 players-hours respectively. Injuries were largely to soft tissues (sprains 26%, haematomas 25%) and to the lower limb (43%). Very few serious injuries occurred (19 fractures and three injuries with loss of consciousness); nearly all of these were in the under-15s. Rule modifications in under-10 teams and clinics were associated with an injury rate of 5.8 injuries per 1000 player-hours (95% CI, 4.4-7.3) compared with 7.5 injuries per 1000 player-hours (95% CI, 5.2-9.8) when no modification was used. Alterations to the ruck contest, decreased contact, field size and player numbers were significantly associated with lower injury rates, while body size was not. Of the 30% of injuries resulting in a health service consultation, the most common health provider was a medical practitioner. Very few required expensive investigation or treatment. CONCLUSION: Injury rates were low in children under age 10, but higher in adolescents. Most injuries were minor, and did not result in a health professional consultation. Rule modifications were associated with substantially lower injury rates at the under-10 level, and should be promoted as a safe way to learn football skills.

Adolescent↗
PubMed1984

Extracellular fluid expansion and autoregulation in nephrotoxic serum nephritis in rats.

Previous studies of the early autologous phase of bilateral nephrotoxic serum nephritis (NSN) in rats showed that whole kidney and single nephron glomerular filtration rate (GFR) were maintained at normal levels despite a 60% reduction in the product of surface area and hydraulic permeability (Kf). Factors responsible for this compensation were an increase of net ultrafiltration pressure, due primarily to an increased glomerular capillary pressure (PGC). This study was designed to investigate some possible causes of the compensation. Rats with bilateral NSN and normal GFR had an increased extracellular fluid volume (ECFV) 2 weeks after induction of NSN; control subjects did not change. To determine whether this ECFV expansion was responsible for triggering the compensation, we developed a unilateral NSN model with one diseased and one normal kidney. Unilaterally diseased rats did not experience an increase of ECFV. Values of Kf were 0.069 +/- 0.012 nl sec-1 mm Hg-1 in control subjects, 0.037 +/- 0.005 in bilateral NSN, and 0.043 +/- 0.006 in unilateral NSN. The elevation in PGC was the same in unilateral NSN as in bilateral NSN subjects and the same was true for the hydrostatic pressure difference across glomerular capillaries (delta P). Furthermore, in paired measurements on both kidneys of rats with unilateral NSN, PGC was significantly higher in the unilaterally diseased kidney than in the nondiseased kidney; sham control subjects had no difference. These results are interpreted to indicate that the signal that causes elevation of net ultrafiltration pressure is not a consequence of a systemic effect of NSN, but arises within the diseased kidney itself. To determine whether that signal involved some change in the mechanisms mediating autoregulation measurements were made of the response of whole kidney GFR and RBF to acute changes in arterial BP. Control rats and rats with NSN autoregulated both GFR and blood flow equally well. Tubuloglomerular feedback was studied by microperfusing loops of Henle and measuring proximal stop-flow pressure and early proximal flow rate. Stop-flow pressure was 4.0 mm Hg higher in rats with NSN at a loop perfusion rate of 10 nl/min, approximately the same difference that was found by direct measurement of PGC, but the sensitivity of response to changes in perfusion rate was the same in NSN as in control subjects. Finally, end proximal tubule flow rate was higher in NSN than in control subjects reflecting decreased proximal reabsorption. Thus, a normal feedback mechanism receives a signal that should cause afferent arteriolar constriction in NSN rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1982

Pindolol: effects on blood pressure and plasma renin activity.

The influence of pindolol, other antihypertensive agents, or placebo upon plasma renin activity (PRA) was examined in five separate studies involving 249 subjects (pindolol), n = 149; propranolol, n = 43; methyldopa, n = 13; chlorthalidone, n = 16; placebo, n = 28). In addition, the subjects were stratified in for studies into low (n = 104), medium (n = 96), or high (n = 15) PRA categories according to baseline PRA and sodium excretion measurements. The response to antihypertensive therapy was analyzed in each PRA category. Pindolol and propranolol lowered PRA comparably at equivalent dosages, although this effect was not consistently observed in all studies or at all dosage levels. Methyldopa therapy was not associated with a decline in PRA and chlorthalidone elevated PRA. Pindolol and propranolol lowered both supine and erect diastolic blood pressure (BP) comparably. This effect was similar in subjects categorized as having low or medium PRA. Too few patients were studied with high PRA to derive statistically meaningful data. Pindolol lowered standing systolic BP to a greater extent than did propranolol, especially in the medium PRA category. It was concluded that pindolol, like other beta-adrenergic blockers, lowers PRA, that the effect of pindolol on diastolic BP is independent of the baseline PRA category, and that pindolol is more effective than propranolol in lowering standing systolic BP, at least in the medium PRA category.

Adult↗
PubMed1982

Slow release dietary carbohydrate improves second meal tolerance.

Breakfasts of lentils or wholemeal bread of identical carbohydrate content were taken by seven healthy volunteers. The lentils produced a significant 71% (p less than 0.001) reduction in the blood glucose area and flattened the plasma insulin and gastric inhibitory polypeptide responses by comparison with the bread. In addition, the lentil breakfast was followed by a significantly flatter blood glucose response to the standard bread lunch which followed 4 h later (by 38%, p less than 0.01). The blood glucose pattern was mimicked by feeding the bread breakfast slowly over the 4 h before lunch. Giving a bread breakfast containing a quarter of the carbohydrate reduced the breakfast glucose profile but resulted in a significantly impaired blood glucose response to lunch (168% of control, p less than 0.01). These results, together with breath hydrogen studies, performed on a separate group of four volunteers, indicate that the flattened response to lentils is not due to carbohydrate malabsorption. Slow release or "lente" carbohydrate foods such as lentils may form a useful part of the diets of those with impaired carbohydrate tolerance.

Adult↗
PubMed1978

Estimation of relative glomerular capillary surface area in normal and hypertrophic rat kidneys.

The quantity of antiglomerular baSEMent membrane antibodies (antiGBM) binding to the glomeruli of rats 4 hr after i.v. injection of 660 microgram of antiGBM was used as a measure of relative glomerular capillary surface area (Sr). Intact immature and adult rats (N = 27) weighing 46 to 440 g were studied to assess the effect of normal growth on Sr. Young adult rats (N = 36) were studied at 0, 8, 15, and 22 days following uninephrectomy or sham operation to assess the effect of hypertrophic kidney growth on Sr. Bound antiGBM increased from 95 microgram to approximately 350 microgram as rats grew from 46 to 200 g; further growth was associated with no further growth was associated with no further increases in bound antiGBM. In contrast, there was no progressive increase in Sr following uninephrectomy or sham operation despite as 45% increase in kidney weight at 22 days over the comparable kidney in the sham-operated rats (1.32 +/- SEM 0.06 g vs. 0.91 +/- SEM 0.01 g, P less than 0.0001). Thus, increases in GFR during early normal kidney growth parallel anatomic increases in Sr, but increases in GFR with later growth or with compensatory hypertrophy in young adult rats are not accompanied by changes in Sr.

Animals↗
PubMed1978

Juxtaglomerular cell tumor.

A 15-year-old female with primary reninism presented with benign hypertension, normokalemia, normal aortagram and normal intravenous pyelogram. The diagnosis was suggested only by a remarkably elevated plasma renin activity (PRA). Selective catheterization of renal vein branches was necessary to make the diagnosis of a tumor. A local resection of the tumor resulted in normalization of blood pressure and PRA. Prior to the definitive surgery, oral propranolol was effective in lowering PRA and blood pressure.

Adolescent↗
PubMed1977

Segmental intrarenal catheterization in renin-mediated hypertension.

Segmental renal vein blood was collected in 9 hypertensive patients who had a focal renal lesion on excretory urography and/or a high peripheral plasma renin activity. The main renal vein catheterization was normal in all patients. Segmental renal vein catheterization demonstrated a renin-producing lesion in 3 patients, all of whom were cured of the hypertension postoperatively. Segmental renal vein catheterization is safe and allows the recognition of increased renin production from focal lesions of the kidney that may not be demonstrated radiographically or by main vein catheterization.

Adolescent↗