PubMed Health⌕ Search

Biomedical subjects

H Mason

Publications and source records attributed to H Mason.

At least 19 recordsLinked to original sources
PubMed2006

Enzyme exposure in the British baking industry.

OBJECTIVES: Enzymes are commonly used in the baking industry, as they can improve dough quality and texture and lengthen the shelf life of the final product. There is little published information highlighting exposure to enzymes (other than fungal alpha-amylase) in the baking industry, therefore the purpose of this study was to identify antibodies and develop assays for the measurement of a variety of such enzymes in samples of airborne flour dust. METHODS: Polyclonal antibodies to bacterial amylase, glucose oxidase and amyloglucosidase were identified and developed into ELISA assays. The assays showed limited cross-reactivity with other enzymes commonly used in the baking industry. RESULTS: We measured levels of airborne enzymes in 195 personal air samples taken from a sample of 55 craft baking establishments. We were able to detect amyloglucosidase in 9% (16/184) of the samples, fungal alpha-amylase in 6% (11/171), bacterial alpha-amylase in 7% (13/195). However, we were unable to detect glucose oxidase in any of the samples. Measurements for protease enzymes were not carried out. Median levels in detectable samples of amyloglucosidase, fungal alpha-amylase and bacterial amylase were similar at 10.3, 5.3 and 5.9 ng/m(3), respectively. These figures represent the total enzyme protein (active and inactive) measured. CONCLUSIONS: There are few data in the literature regarding sensitization and exposure-response relationships to these enzymes, and indeed there is often a lack of information within the industry as to the precise enzyme content of particular baking ingredients. As a precautionary measure, all enzymes are regarded as having the potential to cause respiratory sensitization. Consequently, exposures need to be controlled to as low a level as reasonably practicable, and future investigation may highlight the importance of measuring a variety of enzyme exposures and standardizing these methodologies to inform approaches to adequate control.

Air Pollutants, Occupational↗
PubMed2005

The decay of blood lead levels in workers suspended under the control of lead at work regulations.

AIMS: To study the rate of decline in blood lead levels post-suspension under Control of Lead at Work Regulations (CLAW) and thereby suggest sampling frequencies for follow-up blood lead measurements. METHODS: A retrospective cohort of lead workers with blood lead levels over the current suspension level were identified from blood lead records. Data on their suspension and follow-up blood lead measurements were obtained. RESULTS: Sixteen per cent of the identified cohort did not appear to return to lead work under CLAW. Twenty-seven suspension cases with an initial mean blood lead of 79 microg/dl (3.82 micromol/l) formed the dataset for analysis of decline in blood lead levels. The mean length of time between the blood sample indicating suspension and the first follow-up blood sample was 32 days. The mean length of suspension under CLAW was 61 days. The mean initial rate of blood lead decay was 0.659 microg/dl per day (0.032 micromol/l per day), although with a wide range. The rate of decline in blood lead after suspension was increased by the blood lead level at suspension, but was decreased by increasing past cumulative exposure. CONCLUSIONS: A follow-up blood lead sample 1 month after suspension should show a mean decrease between 13 and 26 microg/dl (0.63-1.25 micromol/l), which is substantially greater than that due to analytical 'noise' associated with two sequential measurements (approximately 5 microg/dl). Therefore, a follow-up blood sample taken around 3-4 weeks after suspension would seem practical. A decrease in blood lead of 7-8 mug/dl (0.36 micromol/l) or less in the month after suspension may suggest continuing lead exposure.

Adult↗
PubMed2005

A prospective study of the effectiveness of group and individual psychotherapy for women CSA survivors.

OBJECTIVES: There is little empirical evidence to guide clinical practice in treating adult patients presenting to adult mental health and primary care services with severe psychological difficulties consequent on childhood sexual abuse. The aim of this study was to determine the effectiveness of a model of short term, focal, integrative psychotherapy with this population of patients and to compare outcomes when the model is delivered on an individual or group basis. DESIGN: This study used a patient preference design with random allocation to one of two treatment modalities (individual or group treatment). There was a waiting list control. METHOD: A group of 48 women patients were assessed on 4 psychological measures when entering a waiting list condition, immediately before treatment and after completion of 12 sessions of psychotherapy, either in a group or individually. Follow-up data were collected at 4 months and 8 months. RESULTS: Both individual and group patients showed highly statistically and clinically significant improvements after treatment. These gains were maintained at follow-up with the exception of one measure that indicated a significant decline from post-treatment levels for the group patients. CONCLUSIONS: This model of psychotherapy is highly effective, when delivered by chartered clinical psychologists to patients whose preferences for individual or group therapy have been met.

Adult↗
PubMed2003

The effect of polycystic ovary syndrome on health-related quality of life.

This article reviews current literature regarding polycystic ovary syndrome (PCOS) and health-related quality of life (HRQoL), as well as examining how some of the manifestations of PCOS affect HRQoL. The only quantitative study was performed in adolescent girls. It used a well-validated instrument and showed that HRQol was worse in those with PCOS in the areas of general health perceptions, behavior, physical functioning and family activity. No comparable study exists for adults with PCOS. However, qualitative psychological studies have demonstrated higher levels of depression, psychological and psychosexual morbidity and an increased response to stress in women with PCOS compared with controls. Low self-esteem, decreased social activity and less romantic contentment were reported in women with PCOS. Weight and hirsutism consistently caused more concern than menstrual problems or infertility. The symptoms associated with PCOS, namely hirsutism, acne, diabetes mellitus and obstructive sleep apnea syndrome (OSAS) were all reported to reduce HRQoL in separate studies. Encouragingly, treatment for acne and OSAS improved the HRQoL, although treatment for hirsutism did not. Quantitative studies on the effect of PCOS on HRQoL and the benefit of treatments need to be conducted.

Female↗
PubMed2003

Land contamination and urinary abnormalities: cause for concern?

AIMS: To determine the prevalence of proteinuira and enzymuria among a cohort of subjects exposed to hexachlorobutadiene (HCBD) in their homes and to determine whether there was a change in observed effects when exposure ceased. METHODS: Residents underwent a health check, which included a panel of urinary markers of both glomerular and tubular origin, within two months of cessation of long term exposure to HCBD and again at least 10 months after exposure ceased. Analysis of the results was performed to determine if there was any early evidence of renal effects, and to ascertain whether changes in these parameters occurred after exposure to HCBD ceased. RESULTS: Tubular proteinuria and enzymuria were increased in the initial health check and significantly decreased after the residents had left their homes for about 10 months. As the early renal tubular markers improved when exposure ceased it is anticipated that the long term nephrotoxic risk will be minimal, but the carcinogenic risk remains unknown. CONCLUSIONS: Results show there was a renal effect which improved when subjects left their homes. This suggests there was a local environmental factor responsible for the observations. This is consistent with the predicted toxicological effects of HCBD from animal studies.

Adolescent↗
PubMed2001

Quantification of cerebral perfusion with "Real-Time" contrast-enhanced ultrasound.

BACKGROUND: No noninvasive technique is currently capable of "real-time" assessment and monitoring of cerebral blood flow (CBF). We hypothesized that cerebral perfusion could be accurately measured and monitored in "real time" with contrast-enhanced ultrasound (CEU). METHODS AND RESULTS: Cerebral perfusion was assessed in 9 dogs through a craniotomy with CEU at baseline and during hypercapnia and hypocapnia while normoxia was maintained. Cerebral microvascular blood volume (A), microbubble velocity (beta), and blood flow (Axbeta) were calculated from time-versus-acoustic intensity relations. Compared with baseline, hypercapnia and hypocapnia significantly increased and decreased CBF, respectively, as measured by CEU. These changes in blood flow were mediated by changes in both A and beta. A good correlation was found between Axbeta derived from CEU and CBF measured by radiolabeled microspheres (y=0.67x-0.04, r=0.91, P<0.001). CONCLUSIONS: Changes in both cerebral microvascular blood volume and red blood cell velocity can be accurately assessed with CEU. Thus, CEU has the potential for bedside measurement and monitoring of cerebral perfusion in real time in patients with craniotomies or burr holes.

Animals↗
PubMed2001

Factors associated with intended staff turnover and job search behaviour in services for people with intellectual disability.

Staff turnover is a major problem in services for people with intellectual disability (ID). Therefore, understanding the reasons for staff turnover is vital for organizations seeking to improve their performance. The present study investigates the factors directly and indirectly associated with an intention to leave an organization and actual job search behaviour amongst staff in services for people with ID. As part of a large-scale survey of staff in services for people with ID, information was collected from 450 staff concerning intended turnover, job search behaviour and a wide range of factors potentially associated with these outcomes. Path analyses revealed that work satisfaction, job strain, younger staff age and easier subjective labour conditions were directly associated with intended turnover. The same factors, with the exception of younger staff age, were also directly associated with job search behaviour. Factors indirectly associated with these outcomes included wishful thinking, alienative commitment to the organization, lack of staff support, role ambiguity, working longer contracted hours, having a low-status job, a lack of influence over decisions at work and less orientation to working in community settings with people with ID. The models of staff turnover empirically derived in the present study confirm and extend previous research in this area. The implications for organizations are discussed.

Adult↗
PubMed2001

Membranous nephropathy, hydrocarbon exposure and genetic variants of hydrocarbon detoxification.

Modulation of biotransformation by genetic traits may be important in determining environmentally-induced nephrotoxicity. We conducted a case-control study to investigate the role of occupational hydrocarbon exposure, along with polymorphisms of the genes coding for N-acetyltransferase 2 (NAT2) and glutathione S-transferase mu (GSTmu), in the development of idiopathic membranous glomerulonephritis (IMGN). Patients (n=36) with biopsy-proven IMGN were matched with healthy controls for age, gender, and geographical area. Lifetime hydrocarbon exposure was assessed by a validated questionnaire. The polymorphisms of the NAT2 and GSTmu genes (GSTM1) were defined by use of a polymerase chain reaction on white-cell DNA from peripheral blood. Exposure to hydrocarbons was significantly greater in patients with IMGN than in controls (mean+/-SEM hydrocarbon exposure score 11 003+/-2955.7 vs. 4352+/-1418, p<0.02). NAT2 acetylator status was identical in patients and controls with 23 (63.9%) fast and 13 (36.1%) slow acetylators in each group. GSTmu was present in 15 (41.7%) patients and 16 (44.4%) controls. While occupational exposure to hydrocarbons remains a likely factor in its pathogenesis, further work is required to identify the genetic polymorphisms that modulate the risk of IMGN.

Arylamine N-Acetyltransferase↗
PubMed2000

Follicular dynamics in the polycystic ovary syndrome.

Anovulation in women with polycystic ovary syndrome (PCOS) is characterised by arrested growth of antral follicles. A relative lack of FSH may contribute to the persistence of anovulation but is unlikely, by itself, to be a major cause of it. Granulosa cells from anovulatory women with polycystic ovaries hypersecrete oestradiol, compared with size-matched follicles from normal ovaries or polycystic ovaries from ovulatory women. This phenomenon appears to reflect a condition of advanced maturation of medium-sized antral follicles. The underlying basis for the abnormalities in anovulatory PCOS remains uncertain, but it is possible that there are intrinsic differences in folliculogenesis between polycystic and normal ovaries which affect preantral as well as antral follicles. An alternative - but not mutually exclusive - explanation of this disorder is the abnormal endocrine environment. Hypersecretion of both LH and insulin are typical of anovulatory women with PCOS. Studies in isolated granulosa cells, have shown, that insulin greatly augments the action of LH on steroidogenesis but this interaction may compromise further growth of medium-sized antral follicles by generation of 'preovulatory' concentrations of cAMP within the granulosa cell and thereby leading, prematurely, to terminal differentiation of granulosa cells.

Anovulation↗
PubMed2000

In-vitro ovarian steroidogenesis in women with pelvic congestion.

Follicular fluid steroid content and theca and granulosa cell steroidogenesis in pelvic congestion cystic ovaries were compared with steroidogenic function in both normal and polycystic ovaries. Ovaries were obtained at oophorectomy for benign gynaecological conditions, and classified according to gross morphology at dissection. Individual follicles were dissected out, follicular fluid aspirated, and granulosa and theca cells cultured in vitro. Androstenedione, progesterone and oestradiol content of the follicular fluid and overlying culture medium were measured by radioimmunoassay. There was a significant elevation of both basal and LH-stimulated androstenedione production by theca from both polycystic ovaries (n = 10; P < 0.005) and pelvic congestion cystic ovaries (n = 8; P < 0.05 and < 0.01 respectively) as compared with normal ovaries (n = 5). Granulosa cells from pelvic congestion ovaries (n = 7) had a diminished oestradiol response to FSH as compared with those from normal ovaries (n = 8). Follicular fluid from the majority of follicles in the pelvic congestion cystic ovaries had a high androgen:oestrogen ratio consistent with atresia. For the first time, pelvic congestion ovaries characterized by predominantly atretic follicles scattered throughout the stroma in a normal volume ovary are reported. Follicular atresia was reflected by reduced granulosa cell responsiveness to FSH, theca cell hyperplasia and increased basal and LH-stimulated androgen production. These ovaries are functionally distinct from polycystic ovaries, which do not have a higher proportion of atretic follicles than normal ovaries.

Adult↗
PubMed2000

The in vitro percutaneous penetration of chlorpyrifos.

Chlorpyrifos is a widely used organophosphate pesticide. In order to study the pharmacokinetics of the penetration of chlorpyrifos through human skin we measured the percutaneous penetration of chlorpyrifos through human skin using an in vitro flow through apparatus. The chlorpyrifos was applied to the skin as a commercial concentrate or as a reference standard dissolved in ethanol. There was a significant difference (P=0.03) between the rate of penetration from the commercial concentrate (9.0 nmoles cm(-2) h(-1)) and that from the reference standard (4.9 nmoles cm(-2) h(-1)). Each experiment was run for 24 h. The recoveries from experiments where chlorpyrifos was applied to the skin as a commercial concentrate and as a reference standard dissolved in ethanol were, respectively, in total 91 and 87% of the applied dose of which 15 and 10% was recovered from the skin, 56 and 66% was recovered from the surface of the skin and 20 and 11% was recovered from the receptor fluid. There was a significant difference in the recoveries from the skin but there was no significant difference in the recoveries from the surface of the skin. We concluded that the majority of a dermal dose of chlorpyrifos was still present at or in the surface of the skin 24 h after application of a dermal dose. Because chlorpyrifos was recovered from the skin after 24 h, it is possible that the skin could act as a reservoir and release chlorpyrifos over a longer period. We also conclude that the solvent vehicle for chlorpyrifos can affect the rate of penetration of the pesticide.

Administration, Cutaneous↗
PubMed1999

Design and structure-activity relationships of potent and selective inhibitors of blood coagulation factor Xa.

The discovery of a series of non-peptide factor Xa (FXa) inhibitors incorporating 3-(S)-amino-2-pyrrolidinone as a central template is described. After identifying compound 4, improvements in in vitro potency involved modifications of the liphophilic group and optimizing the angle of presentation of the amidine group to the S1 pocket of FXa. These studies ultimately led to compound RPR120844, a potent inhibitor of FXa (K(i) = 7 nM) which shows selectivity for FXa over trypsin, thrombin, and several fibrinolytic serine proteinases. RPR120844 is an effective anticoagulant in both the rat model of FeCl(2)-induced carotid artery thrombosis and the rabbit model of jugular vein thrombus formation.

Animals↗
PubMed1999

Organizational culture and staff outcomes in services for people with intellectual disabilities.

Organizational culture has been shown by organizational psychology to influence important aspects of staff behaviour. In particular, mismatches between staff perceptions of real and ideal organizational cultures have been shown to be associated with a range of negative outcomes for staff, such as stress, sickness and staff turnover. The present study investigates organizational culture in services for people with intellectual disabilities. The aim was to discover the prevalent organizational cultures in these services, and associations between organizational culture and staff outcomes. As part of a large-scale survey of staff in services for people with intellectual disabilities, information concerning organizational culture and staff outcomes was collected from 450 staff. A self-report measure of real and ideal organizational culture produced nine dimensions of organizational culture: (I) tolerant/staff-oriented; (2) achievement-oriented; (3) innovative; (4) analytical; (5) social relationships; (6) rewarding staff; (7) stable work environment; (8) demanding; and (9) conflict management. These nine dimensions of organizational culture showed generally adequate psychometric properties. While there was some variation in organizational culture across services, there is little variation across staff with different job titles. Overall, the staff rated real organizational cultures to be relatively high in achievement orientation and fostering social relationships, and relatively low in managing conflict and providing rewards for staff. Staff rated ideal organizational cultures to be high in rewarding staff, being tolerant/staff-oriented and fostering social relationships, and low in demands on staff. Except for the dimension of making demands on staff, where staff rated organizations as considerably higher than ideal, staff generally rated organizations as being less than ideal on all dimensions of organizational culture. Organizational psychology theory predicts that poor 'person-organization fit' (i.e. a greater mismatch between real and ideal organizational culture) will be associated with a range of negative staff outcomes. This theory was largely supported by findings of the present study. The implications for practice and for future research are discussed.

Adaptation, Psychological↗
PubMed1999

Factors associated with staff stress and work satisfaction in services for people with intellectual disability.

Staff stress and morale have been identified as major issues affecting the quality of services for people with intellectual disability. The present study investigates factors directly and indirectly associated with staff general distress, job strain and work satisfaction amongst staff in services for people with intellectual disability. As part of a large-scale survey of staff in services for people with intellectual disability, information was collected from 450 staff concerning general distress, job strain and work satisfaction, and a wide range of factors potentially associated with these outcomes. Path analyses revealed that three factors accounted for 28% of the variance in general distress scores: (I) wishful thinking, (2) stress linked to work-home conflict and (3) role ambiguity. Six factors accounted for 50% of the variance in job strain scores: (I) wishful thinking, (2) stress linked to a lack of staff support, (3) alienative commitment, (4) role ambiguity, (5) stressors linked to a low status job and (6) working longer contracted hours. Six factors accounted for 66% of the variance in work satisfaction scores: (I) stress linked to a low status job, (2) support from supervisors, (3) influence over work decisions, (4) alienative commitment, (5) support from colleagues and (6) older staff age. A range of factors indirectly associated with the three outcome measures was also identified. The models of general distress, job strain and work satisfaction empirically derived in the present study confirm and extend previous research in this area. The implications for organizations and future research are discussed.

Adult↗
PubMed1999

Priming with a secreted form of the fusion protein of respiratory syncytial virus (RSV) promotes interleukin-4 (IL-4) and IL-5 production but not pulmonary eosinophilia following RSV challenge.

The attachment (G) protein of respiratory syncytial virus (RSV) is synthesized as two mature forms: a membrane-anchored form and a smaller secreted form. BALB/c mice scarified with vaccinia virus (VV) expressing the secreted form develop a greater pulmonary eosinophilic influx following RSV challenge than do mice scarified with VV expressing the membrane-anchored form. To determine if a soluble form of an RSV protein was sufficient to induce eosinophilia following RSV challenge, a cDNA that encoded a secreted form of the fusion (F) protein of RSV was constructed and expressed in VV (VV-Ftm(-)). Splenocytes and lung lymphocytes from mice primed with VV-Ftm(-) produced significantly more of the Th2 cytokines interleukin-4 (IL-4) and IL-5 than did mice vaccinated with VV expressing either the native (membrane-anchored) form of the F protein or the G protein. Although mice scarified with VV-Ftm(-) developed a slight increase in the number of pulmonary eosinophils following RSV infection, the increase was not as great as that seen in VV-G-primed mice. Despite the increased IL-4 and IL-5 production and in contrast to mice primed with VV-G, mice primed with VV-Ftm(-) developed RSV-specific cytotoxic T lymphocytes (CTL) and maintained high levels of gamma interferon production. These data demonstrate that recombinant VV strains expressing soluble forms of RSV proteins induce immune responses that are more Th2-like. However, this change alone does not appear sufficient to induce vaccine-augmented disease in the face of active CD8(+) CTL populations.

Animals↗
PubMed1999

Oral and dermal absorption of chlorpyrifos: a human volunteer study.

OBJECTIVES: To determine the kinetics of elimination of urinary dialkylphosphate metabolites after oral and dermally applied doses of the organophosphate pesticide chlorpyrifos to human volunteers and to determine whether these doses affected plasma and erythrocyte cholinesterase activity. METHOD: Five volunteers ingested 1 mg (2852 nmol) of chlorpyrifos. Blood samples were taken over 24 hours and total void volumes of urine were collected over 100 hours. Four weeks later 28.59 mg (81567 nmol) of chlorpyrifos was administered dermally to each volunteer for 8 hours. Unabsorbed chlorpyrifos was washed from the skin and retained for subsequent measurement. The same blood and urine sampling regime was followed as for the oral administration. Plasma and erythrocyte cholinesterase concentrations were determined for each blood sample. The concentration of two urinary metabolites of chlorpyrifos--diethylphosphate and diethyl-thiophosphate--was determined for each urine sample. RESULTS: The apparent elimination half life of urinary dialkylphosphates after the oral dose was 15.5 hours and after the dermal dose it was 30 hours. Most of the oral dose (mean (range) 93% (55-115%)) and 1% of the applied dermal dose was recovered as urinary metabolites. About half (53%) of the dermal dose was recovered from the skin surface. The absorption rate through the skin, as measured by urinary metabolites was 456 ng/cm2/h. Blood plasma and erythrocyte cholinesterase activity did not fall significantly during either dosing regime. CONCLUSION: An oral dose of chlorpyrifos was readily absorbed through the skin and almost all of the dose was recovered as urinary dialkylphosphate metabolites. Excretion was delayed compared with the oral dose. Only a small proportion of the applied dose was recovered during the course of the experiment. The best time to collect urine samples for biological monitoring after dermal exposure is before the shift the next day. The amounts of chlorpyrifos used did not depress acetyl cholinesterase activity but could be readily detected as urinary dialkylphosphate metabolites indicating that the urinary assay is a more sensitive indicator of exposure.

Administration, Cutaneous↗