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.

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.

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.

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.

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.

Manganese neurotoxicity, a continuum of dysfunction: results from a community based study

Excessive manganese (Mn) has been associated with neurobehavioral deficits and neurological and/or neuropsychiatric illness, but the level at which this metal can cause adverse neurotoxic effects, particularly with long-term exposure, is still unknown. The objective of the present study was to assess nervous system functions in residents exposed to manganese from a variety of environmental sources. A random stratified sampling procedure was used to select participants; persons with a history of workplace exposure to Mn and other neurotoxic substances were excluded. A self-administered questionnaire provided data on socio-demographic variables. Blood samples were analyzed for total manganese (MnB), lead, mercury and serum iron. Nervous system assessment included computer and hand-administered neurobehavioral tests, computerized neuromotor tests, sensory evaluation and a neurological examination. The present analyses include 273 persons (151 women and 122 men); MnB range: 2.5 micrograms/L-15.9 micrograms/L (median: 7.3 micrograms/L). Multivariate analyses were used and neuro-outcomes were examined with respect to MnB, taking into account potential confounders and covariables. Results were grouped according to neurofunctional areas and MANOVA analyses revealed that higher MnB (7.5 micrograms/L) was significantly associated with changes in coordinated upper limb movements (Wilks' lambda = 0.92; p = 0.04) and poorer learning and recall (men: Wilks' lambda = 0.77; p = 0.002; women: Wilks' lambda = 0.86; p = 0.04). Further analyses revealed that with increasing log MnB (Simple regression: p < 0.05) performance on a pointing task was poorer, frequency dispersion of hand-arm tremor decreased, while harmonic index increased, and the velocity of a pronation/supination arm movement was slower. An Mn-age interaction was observed for certain motor tasks, with the poorest performance observed among those _50 y and in the higher MnB category. Differences between genders suggest that men may be at greater risk than women, although effects were also observed in women. These findings are consistent with the hypothesis that Mn neurotoxicity can be viewed on a continuum of dysfunction, with early, subtle changes at lower exposure levels.

Bioindicator and exposure data for a population based study of manganese

Exposure data and bioindicators were obtained for a study whose objective was detection of early manifestations of manganese (Mn) neurotoxicity in a population with potential environmental exposure. The study included persons with no history of neurotoxic workplace exposure in Southwest Quebec, drawn from seven postal code regions, defining a set of geographically contiguous zones. Blood samples were analyzed for total Mn (MnB), lead (PbB), total mercury (HgT) and serum iron (FeS). Drinking water samples from participants' residences were analyzed for manganese (MnW). At 4 sites, limited 24-hour high volume air samples for total particulates (TP) and PM10, were analyzed for Mn and Pb. Sociodemographic and dietary information was obtained by self-administered questionnaire. The geometric mean (GM) for MnB values (n = 297) was 7.14 micrograms/L. Levels of MnB in women (n = 156; GM 7.50 micrograms/L) were significantly higher than in men (n = 141; GM 6.75 micrograms/L). No relationship was found between MnB and PbB or HgT. FeS was significantly higher in men (GM 18.38 mumol/L) than women (GM 15.0 mumol/L). For women, MnB was correlated to FeS, with a tendency to decrease with increasing age. For men, no relationship was found between MnB levels and either FeS or age, although FeS showed a strong inverse relationship with age. The 24-hour mean levels of MnTP at the 4 sites varied between 0.009 microgram/m3 and 0.035 microgram/m3; intersite differences were not significant. For Mn in PM10 (MnPM10), mean values ranged from 0.007 microgram/m3 to 0.019 microgram/m3; intersite differences were significant. A total of 278 MnW samples were obtained, 16 from residences served by wells. The GM for MnW was 4.11 micrograms/L (range: 0.50-71.1 micrograms/L, excluding wells; MnW for wells ranged from non-detectable to 158.9 micrograms/L. Individually, there was no relation between MnW and MnB. Geographic analysis of the MnB and MnW data by an algorithm grouping contiguous postal code zones, combined with air data, lead to definition of a geographic parameter, distinguishing two regions relative to a former manganese alloy plant, which contributed significantly to MnB. A multiple regression model was developed, explaining 6.7% of the variability in MnB (F = 5.12; p < 0.001); when controlling for gender, geographic region with higher levels of airborne manganese and the frequency of consumption of cereals and leaf vegetables contributed positively to MnB levels, while serum iron was negatively related.

Preliminary evidence of neurotoxicity associated with eating fish from the Upper St. Lawrence River Lakes

Pollution of hydrographic basins has affected the flora and fauna that thrive in these aquatic ecosystems, and fish, which constitute an important food resource, often contain a plethora of potentially toxic chemicals. In a major research project on early neurotoxic effects of environmental exposure to manganese among residents in Southwest Quebec, fish consumption from 2 lakes of the Upper St. Lawrence River System, was surveyed as a potential confounding factor. Participants were selected using a random, stratified sampling strategy from lists of the Quebec Health Plan. Following exclusions, 273 men and women between 20-69 years were retained for the present analysis. A total of 103 (37.7%) reported eating fish from the Upper St. Lawrence. Although fisheaters and non-fisheaters were similar for most socio-demographic variables, significantly more fisheaters (65.2%) reported consuming alcoholic beverages as compared to non-fisheaters (42.4%) (Chi Sq. <0.01). To eliminate this possible bias, fisheaters were matched to non-fisheaters for the variables sex, alcohol consumption (never or occasionally vs. regularly), age (+/-5y) and education (+/-2y). A total of 63 matched pairs were thus created. Paired analyses (t-test or Signed Rank) showed that fisheaters had higher levels of blood organic mercury and lead. Analysis of nervous system functions revealed that both groups performed similarly on tests of sensory function, visual memory and recognition, fine motor performance and some motor tests, but fisheaters performed significantly more poorly (p<0.05) on tests requiring cognitive flexibility, word naming, auditory recall, and more complex motor tasks. The profile of deficits is consistent with diminished capacity for information processing. These observations were made within a study that was not specifically designed to examine the effects of fish eating from these two lakes, and the characterization of fish dietary habits has many limitations. Nevertheless, the findings are sufficiently compelling to warrant further studies, since fish from the Upper St. Lawrence Lakes are known to contain multiple neurotoxic substances.

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.

Predicting the probability for falls in community-dwelling older adults

BACKGROUND AND PURPOSE

The objective of this retrospective case-control study was to develop a model for predicting the likelihood of falls among community-dwelling older adults.

SUBJECTS

Forty-four community-dwelling adults (> or = 65 years of age) with and without a history of falls participated.

METHODS

Subjects completed a health status questionnaire and underwent a clinical evaluation of balance and mobility function. Variables that differed between fallers and nonfallers were identified, using t tests and cross tabulation with chi-square tests. A forward stepwise regression analysis was carried out to identify a combination of variables that effectively predicted fall status.

RESULTS

Five variables were found to be associated with fall history. These variables were analyzed using logistic regression. The final model combined the score on the Berg Balance Scale with a self-reported history of imbalance to predict fall risk. Sensitivity was 91%, and specificity was 82%.

CONCLUSION AND DISCUSSION

A simple predictive model based on two risk factors can be used by physical therapists to quantify fall risk in community-dwelling older adults. Identification of patients with a high fall risk can lead to an appropriate referral into a fall prevention program. In addition, fall risk can be used to calculate change resulting from intervention.

The effects of two types of cognitive tasks on postural stability in older adults with and without a history of falls

BACKGROUND

This study used a dual task design to investigate the effects of two different types of cognitive tasks on stability (as measured by center of pressure displacement) in young vs older adults with and without a history of falls.

METHODS

Two secondary cognitive tasks, a sentence completion and a visual perceptual matching task, were used to produce changes in attention during quiet stance under flat vs compliant surface conditions in 20 healthy young adults, 20 healthy older adults, and 20 older adults with a history of imbalance and falls. Postural stability was quantified using forceplate measures of center of pressure (COP). Speed and accuracy of verbal response on the cognitive tasks were also quantified.

RESULTS

During the simultaneous performance of a cognitive and postural task, decrements in performance were found in the postural stability measures rather than the cognitive measures for all three groups. While no differences were found between the young adults and the older healthy adults on the firm surface, no task condition, when task complexity was increased (either through the introduction of a secondary cognitive task, or a more challenging postural condition such as standing on the compliant surface), significant differences in postural stability between the two groups became apparent. In contrast to the young and healthy older adults, postural stability in older adults with a history of falls was significantly affected by both cognitive tasks.

CONCLUSION

Results suggest that when postural stability is impaired, even relatively simple cognitive tasks can further impact balance. Results further suggest that the allocation of attention during the performance of concurrent tasks is complex; depending on many factors including the nature of both the cognitive and postural task, the goal of the subject and the instructions.

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.

The effect of multidimensional exercises on balance, mobility, and fall risk in community-dwelling older adults

BACKGROUND AND PURPOSE

This prospective clinical investigation examined the effects of a multidimensional exercise program on balance, mobility, and risk for falls in community-dwelling older adults with a history of falling. Factors used to predict adherence and a successful response to exercise were identified.

SUBJECTS

A total of 105 community-dwelling older adults (> or = 65 years of age) with a history of two or more falls in the previous 6 months (no neurologic diagnosis) participated. They were classified into (1) a control group of fallers (n = 21), (2) a fully adherent exercise group (n = 52), and (3) a partially adherent exercise group (n = 32).

METHODS

Following evaluation, each patient received an individualized exercise program addressing the impairments and functional disabilities identified during the assessment. The control group received no intervention. Changes in performance on five clinical tests of balance and mobility and fall risk were compared among groups.

RESULTS

Both exercise groups scored better than the control group on all measures of balance and mobility. Although both exercise groups showed a reduction in fall risk compared with the control group, the greatest reduction was found in the fully adherent exercise group. Factors associated with successful response to exercise included degree of adherence to exercise program and pretest score on the Tinetti Mobility Assessment.

CONCLUSION AND DISCUSSION

Exercise can improve balance and mobility function and reduce the likelihood for falls among community-dwelling older adults with a history of falling. The amount of exercise needed to achieve these results, however, could not be determined from this study.

Solid-state NMR studies of the prion protein H1 fragment

Conformational changes in the prion protein (PrP) seem to be responsible for prion diseases. We have used conformation-dependent chemical-shift measurements and rotational-resonance distance measurements to analyze the conformation of solid-state peptides lacking long-range order, corresponding to a region of PrP designated H1. This region is predicted to undergo a transformation of secondary structure in generating the infectious form of the protein. Solid-state NMR spectra of specifically 13C-enriched samples of H1, residues 109-122 (MKHMAGAAAAGAVV) of Syrian hamster PrP, have been acquired under cross-polarization and magic-angle spinning conditions. Samples lyophilized from 50% acetonitrile/50% water show chemical shifts characteristic of a beta-sheet conformation in the region corresponding to residues 112-121, whereas samples lyophilized from hexafluoroisopropanol display shifts indicative of alpha-helical secondary structure in the region corresponding to residues 113-117. Complete conversion to the helical conformation was not observed and conversion from alpha-helix back to beta-sheet, as inferred from the solid-state NMR spectra, occurred when samples were exposed to water. Rotational-resonance experiments were performed on seven doubly 13C-labeled H1 samples dried from water. Measured distances suggest that the peptide is in an extended, possibly beta-strand, conformation. These results are consistent with the experimental observation that PrP can exist in different conformational states and with structural predictions based on biological data and theoretical modeling that suggest that H1 may play a key role in the conformational transition involved in the development of prion diseases.

Expression of HIV regulatory and structural mRNA in the central nervous system

OBJECTIVE

HIV encephalitis is observed in approximately one-half of AIDS autopsies. Although most investigators would agree that central nervous system (CNS) macrophages are the predominant infected cell in HIV encephalitis, there remains some controversy regarding whether other CNS cells can be infected by HIV and thus show the molecular characteristics of such an infection.

DESIGN AND METHODS

Using reverse transcriptase polymerase chain reaction (PCR) and immunocytochemistry (ICC), we examined CNS tissues from AIDS and control autopsies for the presence of non-productive HIV infection.

RESULTS

Single-spliced mRNA for structural envelope proteins were detected in the basal ganglia of only one of nine HIV-seropositive autopsies without HIV encephalitis and none of five seronegative autopsy controls. Double-spliced mRNA for regulatory proteins (e.g., Nef and Tat) were not detected in either the seropositive non-HIV encephalitis or seronegative controls. Both single and double-spliced viral RNA could be detected in basal ganglia of 10 out of 13 autopsies with HIV encephalitis. Similar findings were obtained when cerebral white matter was examined. Using PCR primers that distinguish single from double-spliced mRNA, we found no evidence for selective expression of the Nef regulatory gene.

CONCLUSIONS

These data suggest that expression of HIV mRNA in the CNS is limited to those patients with HIV encephalitis. Further HIV encephalitis appears to be a chronic permissive infection of the CNS, without evidence of restricted Nef transcript expression.

Macrophage Activation Factors in the Brains of AIDS Patients

HIV, soluble HLA class I (sHLA-I), quinolinic acid (QUIN), and the monokines IL-1&beta;, IL-6, and TNF-&#945; were measured by ELISA and PCR in brain tissue of 60 AIDS autopsies without evidence of CNS opportunistic infections. Individual cases showed good interrogational correlations for the factors measured. There was a positive correlation between concentrations of IL-1&beta; and IL-6. Brain viral burden correlated with intraparenchymal levels of sHLA-I, IL-1&beta;, and IL-6. Comparison of neuritic damage and levels of immune mediators implicates macrophage activation factors in the etiology of neurologic damage in AIDS.

High-level expression and characterization of a purified 142-residue polypeptide of the prion protein

The major, and possible only, component of the infectious prion is the scrapie prion protein (PrPSc); the protease resistant core of PrPSc is PrP 27-30, a protein of approximately 142 amino acids. PrPSc is derived from the cellular PrP isoform (PrPC) by a post-transliatonal process in which a profound conformational change occurs. Syrian hamster (SHa) PrP genes of varying length ranging from the N- and C- terminally truncated 90-228 up to the full-length mature protein 23-231 were inserted into various secretion and intracellular expression vectors that were transformed into Escherichia coli deficient for proteases. Maximum expression was obtained for a truncated SHaPrP containing residues 90-231, which correspond to the sequence of PrP 27-30; disruption of the bacteria using a microfluidizer produced the highest yields of this protein designated rPrP. After solubilization of rPrP in 8 M GdnHC1, it was purified by size exclusion chromatography and reversed phase chromatography. During purification the recovery was approximately 50%, and from each liter of E. coli culture, approximately 50 mg of purified rPrP was obtained. Expression of the longer species containing the basic N-terminal region was less successful and was not pursued further. The primary structure of rPrP was verified by Edman sequencing and mass spectrometry, and secondary structure determined by circular dichroism and Fourier transform infrared spectroscopy. When rPrP was purified under reducing conditions, it had a high beta-sheet content and relatively low solubility similar to PrPSc, particularly at pH values > 7. Refolding of rPrP by oxidation to form a disulfide bond between the two Cys residues of this polypeptide produced a soluble protein with a high alpha-helical content similar to PrPC. These multiple conformations of rPrP are reminiscent of the structural plurality that characterizes the naturally occurring PrP isoforms. The high levels of purified rPrP which can now be obtained should facilitate determination of the multiple tertiary structures that Prp can adopt.

The views of parents of hearing impaired children on the need for neonatal hearing screening

Much research is now being undertaken into the implementation of universal neonatal hearing screens, but consumer opinion about such screening has not been widely available. The opinions of the parents of 356 children and young adults, with varying degrees of permanent hearing impairment were sought for the current study. They were questioned about their satisfaction with the age at which the hearing impairment was confirmed to be present in their child. Of 208 responses, only 58 were reasonably satisfied with the age at which their child's impairment had been confirmed. They were also asked whether they would have wanted a neonatal hearing screen had it been available. The overwhelming majority (166) would have welcomed such a test. This opinion was shared by the parents, even when their child had a mild or unilateral impairment. Parental comments about the advantages and disadvantages of neonatal screening are discussed.