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Biomedical subjects

M Baldwin

Publications and source records attributed to M Baldwin.

At least 19 recordsLinked to original sources
PubMed2007

Neurobehavioral functioning after cessation of manganese exposure: a follow-up after 14 years.

BACKGROUND: Little is known on the long-term course of early manganese (Mn) neurotoxic effects. Mn alloy workers were examined in a follow-up study 14 years after exposure ceased at a Canadian facility. METHODS: The same battery of neurofunctional tests used in the initial examination in 1990 was administered to 77 Mn-workers and 81 referents in 2004. RESULTS: Manganese-workers had poorer scores compared to referents both in the initial and follow-up examinations for several motor tasks of the Luria Motor Scale. At follow-up, older Mn-workers (>45 years at cessation of exposure) had poorer scores than referents for tests of cognitive flexibility. Cumulated exposure was associated with poorer test scores for certain neuromotor and cognitive tests and on a mood scale. Differences on certain tests observed at initial examination were not present at follow-up. CONCLUSIONS: Manganese exposure was associated with persistent deficits for certain neuromotor functions, cognitive flexibility, and adVerse mood states, while recovery occurred for other functions.

Air Pollutants, Occupational↗
PubMed2006

Reduction meatoplasty with a post-auricular island flap.

The importance of an adequate meatoplasty is often emphasised in mastoid surgery. However, bigger is not always better, as an excessively widened external meatus can be cosmetically unacceptable, provide little extra benefit for cleaning, be an obstacle to the good fitting of hearing aids and expose the mastoid cavity to exaggerated caloric effect. The problems created by an overly large meatus can occasionally be difficult to manage, prompting consideration of reduction of the meatus. We describe the use of a pedicled, post-auricular skin flap to achieve reduction of an excessively large meatus.

Ear Deformities, Acquired↗
PubMed2005

Field and model investigations of external gamma dose rates along the Cumbrian coast, NW England.

A survey of the contribution to external dose from gamma rays originating from intertidal sediments in the vicinity of the British Nuclear Group Sellafield site showed that the major anthropogenic contributions were due to (137)Cs and (60)Co. At some sites, traces of other anthropogenic radionuclides were detected, namely (106)Ru, (125)Sb, and (154)Eu. The proportions of fine grained material (<63 microm) were used to improve model predictions of dose contribution due to external exposure to gamma rays, using the CUMBRIA77/DOSE77 model. Model dose predictions were compared to those directly measured in the field. Using the new proportions of fine grained material (1-17.5%) in conjunction with field gamma-ray spectra, model predictions were improved considerably for most sites. Exceptions were at Drigg Barn Scar and Whitehaven Coal Sands sites, which had their own unique characteristics. The highest (60)Co activity concentrations in this study were detected at Drigg Barn Scar. These relatively high activity concentrations of (60)Co were due to the presence of (60)Co in mussels and barnacles, hence upsetting the fine sediment relationships used in previous dose calculations. Whitehaven Coal Sands was unusual in that it contained higher levels of radionuclides than would be expected in sandy sediment. The mineralogy of these sediments was the controlling factor on (137)Cs binding, rather than the proportion of fine grained material. By adjusting the effective fine grained sediment proportions for calculations involving (60)Co and (137)Cs at Drigg Barn Scar and Whitehaven Coal Sands respectively, the CUMBRIA77/DOSE77 model predictions could be improved upon significantly for these sites. This work highlights the influence of particle size and sediment composition on external dose rate calculations, as well as the potential for external dose contributions from biota.

Animals↗
PubMed2002

Malignancies of the external auditory canal and temporal bone: a review.

BACKGROUND: Malignancies of the external auditory canal and temporal bone are uncommon. A retrospective review was conducted of a large series treated at the Prince of Wales hospital between 1974 and 1995. METHODS: Retrospective review of 59 cases of ear canal and temporal bone malignancies. These were analysed according to histopathology, disease extent, surgery, margin status and survival. A TNM-type staging system was applied to 51 cases and Kaplan-Meier survival analysis applied to this group. RESULTS: The 5-year cancer-specific survival (CSS) for the series was 54%. For stages 1, 2, 3 and 4 disease, the CSS were 90, 45, 40 and 19%, respectively. Survival was significantly higher where clear surgical margins were achieved (80 vs 35%). CONCLUSIONS: Carcinoma of the external ear canal is rare and, in Australia, is often related to recurrence of periauricular cutaneous malignancy. Surgical extirpation with clear margins provides the best survival.

Adult↗
PubMed2001

Cumulative exposure to styrene and visual functions.

BACKGROUND: Results from a 1990-1992 longitudinal study of several reinforced plastics plants showed that for those workers whose styrene exposure had decreased, color vision (CV) improved; while near visual contrast sensitivity (CS) was poorer. METHODS: In 1999, we retested these visual functions in 18 workers with good visual acuity. A cumulative exposure index (CEI), corrected for respirator use, was calculated for each worker. RESULTS: Intra-individual comparison of mandelic acid (MA) showed a significant decrease over time (Friedman; P = 0.015), but current values were not related to CEI. For CV, no significant difference was observed between 1992 and 1999; present results were not related to MA or CEI. The CS profile decreased over time, with significant differences at 3 cpd (Friedman; P < 0.05). CS did not vary with MA levels, but was significantly depressed at the intermediate frequencies among those in the upper CEIH category (Kruskal-Wallis; P < 0.05). CONCLUSIONS: These findings suggest that CS loss increases with long-term cumulative exposure, reflecting chronic damage to the neuro-optic pathways.

Adult↗
PubMed2001

A model for providing prenatal health care to indigenous women living in remote areas.

OBJECTIVE: To describe a model for providing health care services for indigenous women of childbearing age who do not have ready access to health care. STUDY DESIGN: Program description and prospective annual survey medical records. RESULTS: Measures of the success of this model of prenatal care include prenatal care initiated in the first trimester of pregnancy, low preterm birth, and low out of hospital birth. In 1985, the first year statistics were maintained, 31 percent of women entered prenatal care in their first trimester, 58 percent in their second trimester and 11 percent in their third trimester. In 1999, ninety-one percent of women initiated prenatal care in their first trimester, 9 percent in their second trimester and none waited until their third trimester to initiate care. This compares favorably with Indian Health Service data indicating that in Alaska 77.4 percent of women with live births entered care in their first trimester of pregnancy. CONCLUSION: The Rural Maternal Child Health program at Alaska Native Medical Center has been successfully providing services to indigenous women and their families in 30 remote Alaska Native Villages.

Alaska↗
PubMed2001

[Association between work exposure to neurotoxic substances with workers' relationships with their social network].

BACKGROUND: This study explored the impact on family life and social relations that may result from symptoms associated with exposure to neurotoxic substances in the workplace. We assessed the associations between exposure to neurotoxic substances in the workplace, workers'mental health, and workers'relationships with their social network. METHODS: A sample of 53 workers and their spouse completed a series of questionnaires, an interview on work history, and a structured interview assessing their personal relationships. Exposure to neurotoxic substances in the workplace were assessed by an interview, using a semiquantitative classification system. Mental health was measured with the Profile of Mood States (POMS), and marital satisfaction with the Marital Adjustment Test (MAT). The social network's characteristics were assessed with the Northern California Community Study Interview Schedule (NCCS). The associations between exposure and social networks were assessed with regression analyses. RESULTS: There were no associations between exposure and marital satisfaction. However, we found a negative association between workers'exposure and degrees of overlap between husbands' and wives' social networks (Pearson's correlation r=-0.27; p<0.05) and a positive association between exposure and workers' dependency on their support network (r=0.46; p<0.01). CONCLUSION: The results are discussed in terms of variables potentially linking exposure to social relationships as well as in terms of couples' vulnerability to marital distress among exposed workers.

Adult↗
PubMed2000

Beyond the workplace: an exploratory study of the impact of neurotoxic workplace exposure on marital relations.

BACKGROUND: The impact on family life and social relations that may result from symptoms associated with exposure to neurotoxic substances has never been addressed. This exploratory study assessed the associations between exposure to neurotoxic agents in the workplace, mental health, and marital difficulties. METHODS: Fifty-five (55) male workers and their spouses completed standardized measures of mental health and marital difficulties. Workers' exposure to neurotoxic substances was evaluated by questionnaire and interview, using a semiquantitative classification system. RESULTS: A positive relation was observed between exposure level and measures of workers' psychological symptoms and marital stress; no relation was observed between workers' exposure level and wives' psychological symptoms. More severe exposure to neurotoxic substances was associated with wives' reports of more severe marital conflicts, and this association was mediated by husbands' psychological symptoms. As compared to low exposure husbands, high exposure husbands reported higher degrees of stress surrounding marital discussions, more consistent incidence of minor physical assaults by wives, and stronger associations between their levels of stress, the verbal aggressions of wives, and the number of marital conflicts. CONCLUSIONS: The results of this study confirm that neurotoxic exposure is a risk factor for mental health and suggest how this may influence marital relations. Because of the importance of these findings for the well-being of workers and their families, these associations should be further studied.

Animals↗
PubMed2000

Craniofacial resection for paranasal sinus cancers.

BACKGROUND: Combined anterior craniofacial resection (CFR) has been in use for more than 25 years. The advent of the free revascularized tissue transfer flap in l980 permitted safe resection of tumors that had spread beyond the confines of the paranasal sinuses with immediate reconstruction of the sino-orbital cranial defect. The purpose of this study was to examine the outcomes and morbidity of a management policy of primary CFR and postoperative radiotherapy for paranasal sinus cancers infiltrating the skull base over a 21-year period. METHODS: Seventy-three patients with paranasal sinus cancers were treated at the Prince of Wales Hospital between l975 and l996. All were newly diagnosed with the exception of one patient who had received radiotherapy elsewhere 5 years earlier. Only 22% were early lesions and 31% were advanced (more than six sites involved). There were 59 men and 14 women. The mean age was 57 years. All but two patients had a performance status of either 0 or 1. Orbital exenteration was performed in 31 patients. Since l980, all major defects were reconstructed with free tissue transfer flaps. RESULTS: The 5-year cancer-specific survival (CSS) for the 73 patients was 69%, which was unchanged at 10 years. Twenty two patients died from or with their index cancer. An additional 11 patients died from unrelated causes. The actuarial overall survival (OS) at 5 and 10 years was 61% and 48%, respectively. The 5-year recurrence-free rate was 59%. The CSS for the three dominant pathologic conditions were adenocarcinoma 70%, squamous cancer 51%, and olfactory neuroblastoma 84%. The difference was not significant; however, there was a significant difference in OS, with olfactory neuroblastoma having the best prognosis. Orbital involvement, radiologic evidence of skull base erosion, and involvement of the infratemporal fossa were not poor prognostic indicators. Patients with a performance status of 0 had improved OS. There was no operative mortality. CONCLUSIONS: An aggressive policy of combined CFR and postoperative radiotherapy with free-flap reconstruction for large defects gave survival results that were comparable to less-advanced lesions and superior to many other treatment alternatives. There was a high exenteration rate (42%). Squamous cancers were associated with the greatest morbidity and poorest OS.

Adult↗
PubMed2000

Manual wheelchair pushrim biomechanics and axle position.

OBJECTIVE: The biomechanics of wheelchair propulsion have been linked to upper extremity injury. Specifically, prior studies have correlated increased median nerve dysfunction with increasing propulsion frequency and a higher rate of rise of the resultant, or total, pushrim force. Despite this link, there is little research on the effect of wheelchair setup on propulsion biomechanics. The objective of this study was to determine the effect of rear axle position relative to the shoulder on pushrim biomechanics. DESIGN: Case series. SETTING: Biomechanics laboratory. PARTICIPANTS: Forty individuals with paraplegia who use manual wheelchairs for mobility. INTERVENTION: Subjects propelled their own wheelchairs on a dynamometer at two different steady-state speeds and going from a dead stop to maximum speed. Bilateral biomechanical data were obtained using a force- and moment-sensing pushrim and a motion analysis system. MAIN OUTCOME MEASURES: Position of the axle relative to the shoulder at rest both horizontal (XPOS) and vertical (YPOS), and pushrim biomechanical variables including frequency of propulsion, peak and rate of rise of the resultant force, planar moment, and push angle. Partial correlation coefficients between relative axle position and propulsion biomechanics variables were calculated. RESULTS: After controlling for subject characteristics, XPOS was significantly correlated with the frequency of propulsion (p < .01) and the rate of rise of the resultant force (p < .05). In addition, both XPOS and YPOS were significantly correlated with the push angle at multiple speeds (p < .05). CONCLUSION: Specific biomechanical parameters known to correlate with median nerve injuries were found to be related to axle position relative to the shoulder. Providing wheelchair users with adjustable axle position and then fitting the user to the wheelchair can improve propulsion biomechanics and likely reduce the risk of injury.

Adult↗
PubMed2000

Assessment of exposure to manganese in welding operations during the assembly of heavy excavation machinery accessories.

Welder exposure to metals in various industrial sectors is poorly characterized. We had the opportunity to carry out an exploratory study to characterize manganese exposure in welding operations in a recently established Quebec factory that assembled accessories for heavy excavation machinery. Ten workers were sampled for total manganese for at least two consecutive days out of three followed by two consecutive days for respirable manganese (with a size selective sampler with a median cut-off of 4 microns), during a typical week in the summer of 1998. Parts being welded were characterized as large or small. Small parts were those being welded on tables during subassembly. Workers were divided into two groups according to the parts they were welding. Seventy-eight percent of the total manganese exposure levels of welding operations during the assembly of large accessories of heavy excavation machinery exceeded the manganese American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 0.20 mg/m3 (GM 0.24 mg/m3, n = 14) while none exceeded the TLV during the assembly of small pieces (GM 0.06 mg/m3, n = 8). Welding operations during the assembly of large heavy excavation machinery accessories may pose a significant health hazard. Considering the importance of task-related variables affecting exposure among workers, further studies are needed to better characterize exposure determinants of welding operations during the assembly of heavy excavation machinery accessories.

Adult↗
PubMed1999

Confirmation of deafness in infancy.

AIM: To assess delay in confirming hearing impairment in infants identified by universal neonatal screening and to investigate the causes. PATIENTS: Infants identified from 25 199 babies screened from January 1992 to December 1997. METHODS: A two stage transient evoked oto-acoustic emission test (TEOAE), with a threshold auditory brainstem response (ABR) recording undertaken on those who failed. The screen identified infants with a permanent congenital hearing impairment (PCHI) averaging 40 dBnHL or worse in the best ear. Those with less impairment were also ascertained. The positive predictive value (PPV) of the ABR test and measures of delay between identification and eventual diagnosis were analysed. RESULTS: A targeted PCHI was found in 1.18/1000 neonates. The PPV of the ABR for confirming a targeted PCHI was 100% when the ABR threshold was >/= 80 dBnHL. Nine of 11 infants with this threshold had severe or profound permanent deafness. The delay from ABR to audiological certainty was about 1 month-diagnosis was confirmed around 3 months. There was uncertainty when the ABR was 40-80 dBnHL. The PPV was 60% and 8% when the ABR thresholds were 70 dBnHL and 50 dBnHL, respectively. 85 of 111 infants with ABR thresholds in this range had a temporary conductive impairment. Their early diagnosis depended upon the type and degree of hearing impairment and diagnosis was delayed to about 8 months in these infants. CONCLUSIONS: Hearing impairments identified by universal screening are delayed in all but those with severe or profound bilateral PCHI. This delay can be reduced by applying in early infancy a battery of audiological tests and requires further exploration.

Acoustic Impedance Tests↗
PubMed1998

Maternal anxiety and attitudes to universal neonatal hearing screening.

Neonatal hearing screening of all babies within the maternity unit is now feasible using transient evoked otoacoustic emission (TEOAE) recording. However, in many maternity units in the United Kingdom, the majority of babies are discharged within the first 48 hours. During the first two days of life, there is a higher proportion of babies in whom emissions cannot be recorded. A universal TEOAE hearing screen has been implemented in Whipps Cross Hospital. As 70% of the babies are discharged from the maternity unit before they are 48 hours old, a two stage screen was implemented, with failure at the initial TEOAE test being followed by a retest after 4-6 weeks. The maternal anxiety caused by this model was investigated in 288 mothers enrolled for the initial TEOAE test. Generally, anxiety was low and attitudes towards the screen were positive. Ninety-seven per cent of mothers considered the screen to be worthwhile at the initial test with 15% feeling it had caused some anxiety but less than 1% being very worried. The mothers who had some anxieties were not dissatisfied with the screen, and within this group there was no increase in the proportion of babies who had failed the initial test. At the retest, two of 57 mothers (3.5%) considered they were very worried, but there was no significant deterioration in attitude towards the screen. Spielberger's State-Trait Anxiety Inventory revealed no significant difference in the anxiety state of the retest group when compared with a control group whose babies had not received a neonatal hearing test. The results of the initial test and the retest did not influence the anxiety state of the mothers. Ways of minimizing anxiety caused to a minority of mothers whilst maintaining positive attitudes to the screen are discussed.

Anxiety↗
PubMed1997

Early manifestations of manganese neurotoxicity in humans: an update.

It is possible to detect early signs of neurotoxic dysfunction associated with occupational and environmental exposure to manganese; neurophysiologic and neurobehavioral tests can be used in the absence of clinical manifestations. Although outcomes from individual studies vary, they collectively show a pattern of slowing motor functions, increased tremor, reduced response speed, enhanced olfactory sense, possible memory and intellectual deficits, and mood changes. This overall portrait is consistent with the action of manganese on the central nervous system. In reports to date, there is little consistency in dose-effect relationships between internal parameters of manganese exposure (blood manganese, urinary manganese, hair manganese) and external measures and neurologic outcomes. Several studies suggest the existence of dose-effect relationships, but additional clarification is needed.

Environmental Exposure↗