Development of a virtual reality training curriculum for laparoscopic cholecystectomy

Background

Training within a proficiency-based virtual reality (VR) curriculum may reduce errors during real surgical procedures. This study used a scientific methodology for development of a VR training curriculum for laparoscopic cholecystectomy.

Methods

Inexperienced (had performed fewer than ten laparoscopic cholecystectomies), intermediate (20–50) and experienced (more than 100) surgeons were recruited. Construct validity was defined as the ability to differentiate between the three levels of experience, based on simulator-derived metrics for nine basic skills, four procedural tasks and full laparoscopic cholecystectomy on a high-fidelity VR simulator. Inexperienced subjects performed ten repetitions for learning curve analysis. Proficiency measures were based on the performance of experienced surgeons.

Results

Thirty inexperienced, 11 intermediate and 16 experienced operators were recruited. Eight of nine basic skills and three of four procedural tasks were found to be construct valid. The full procedure revealed significant intergroup differences for time (1541, 673 and 816 s; P = 0·002), movements (1021, 595 and 638; P = 0·006) and path length (2038, 1235 and 1303 cm; P = 0·033). Learning curves plateaued between the second and ninth sessions.

Conclusion

This study shows that it is possible to define and develop a whole-procedure VR training curriculum for laparoscopic cholecystectomy using structured scientific methodology.

Closing the treatment gap for dementia in India

There is a rich epidemiological evidence base on dementia in India which shows that this neurodegenerative condition is an important public health problem, particularly in the context of the rapid demographic transition in many parts of the country. Research has shown that most people with dementia, and their caregivers, have significant unmet health and social welfare needs. Due to the great shortage of health care resources and the low levels of awareness about dementia, interventions addressing the needs of the people should be home based and directed at improving quality of life of the person with dementia and the caregiver. In view of the lack of specialists to deal with dementia, a group in Goa developed an alternate model of care which involved training lay health workers to provide home-based care for people with dementia under the supervision of a psychiatrist. This was successfully implemented and evaluated in a randomized controlled trial which showed clear benefits. This article concludes by considering the implication of these findings on strategies for scaling up services and close the treatment gap for dementia in India.

The effectiveness of a home care program for supporting caregivers of persons with dementia in developing countries: a randomised controlled trial from Goa, India

Objectives

To develop and evaluate the effectiveness of a home based intervention in reducing caregiver burden, promoting caregiver mental health and reducing behavioural problems in elderly persons with dementia.

Methodology and Principal Findings

This was a randomised controlled trial in which the person with dementia-caregiver dyad was randomly allocated either to receive the intervention immediately or to a waiting list group which received the intervention after 6 months. It was carried out in communities based in two talukas (administrative blocks) in Goa, India. Mild to moderate cases with dementia (diagnosed using the DSM IV criteria and graded using the Clinical Dementia Rating scale) and their caregivers were included in the trial. Community based intervention provided by a team consisting of Home Care Advisors who were supervised by a counselor and a psychiatrist, focusing on supporting the caregiver through information on dementia, guidance on behaviour management, a single psychiatric assessment and psychotropic medication if needed. We measured caregiver mental health (General Health Questionnaire), caregiver burden (Zarit Burden Score), distress due to behavioural disturbances (NPI-D), behavioural problems in the subject (NPI-S) and activities of daily living in the elder with dementia (EASI). Outcome evaluations were masked to the allocation status. We analysed each outcome with a mixed effects model. 81 families enrolled in the trial; 41 were randomly allocated to the intervention. 59 completed the trial and 18 died during the trial. The intervention led to a significant reduction of GHQ (−1.12, 95% CI −2.07 to −0.17) and NPI-D scores (−1.96, 95%CI −3.51 to −0.41) and non-significant reductions in the ZBS, EASI and NPI-S scores. We also observed a non-significant reduction in the total number of deaths in people with dementia in the intervention arm (OR 0.34, 95% CI 0.01 to 1.03).

Conclusion

Home based support for caregivers of persons with dementia, which emphasizes the use of locally available, low-cost human resources, is feasible, acceptable and leads to significant improvements in caregiver mental health and burden of caring.

ClinicalTrials.gov NCT00479271

CLN2/TPP1 deficiency: the novel mutation IVS7-10A>G causes intron retention and is associated with a mild disease phenotype

The classical form of late infantile neuronal ceroid lipofuscinosis (LINCL) is a childhood hereditary neurodegenerative disease usually fatal in the first decade of life. The underlying gene, CLN2, encodes the lysosomal soluble enzyme tripeptidyl-peptidase 1 (TPP1). In a Portuguese patient with juvenile form of the disease, the histochemical study revealed the presence of curvilinear inclusions typical of LINCL. In vitro TPP1 activity was deficient in patient's cells. CLN2 gene analysis revealed the transition IVS7-10A>G (g.4196A>G) in both alleles. In silico analysis suggested that A-to-G change in the A-rich region of intron 7 could cause aberrant splicing of exon 8 by creating a novel acceptor splice site. However, because the wild-type acceptor of intron 7 is weak and it was not apparently affected, the severity of this mutation could not be established through sequencing data of gDNA. Normal level of spliced CLN2/mRNA was observed in patient's fibroblasts. In the cDNA, the 9-nt retention of intronic sequence (c.886_887ins9) was observed. The mutation is predicted to result in a protein with three extra amino acids between proline 295 and glycine 296. In patient's fibroblasts the level of mutant CLN2p was reduced to about 60% but the migration pattern was similar to the wild-type protein, suggesting that it was correctly targeted to the lysosomes. Taken together, these findings suggest that the first "ag" is selected for splicing and the mutant protein must retain some residual catalytic activity, thus explaining the late onset and the delayed progression of the disease.

Stereotypies in Rett syndrome: Analysis of 83 patients with and without detected MECP2 mutations

BACKGROUND

Hand stereotypies are considered a hallmark of Rett syndrome (RTT) and are usually described as symmetric movements at the midline. However, related pathologies may show the same type of involuntary movement. Furthermore, patients with RTT also have stereotypies with other localizations that are less well characterized.

METHODS

We analyzed stereotypies in 83 patients with RTT, 53 with and 30 without a mutation detected in the MECP2 gene. Patients were observed and videotaped always by the same pediatric neurologist. Stereotypies were classified, and data were submitted to statistical analysis for comparison of mutation-positive and -negative patients and analysis of their evolution with the disease.

RESULTS

All the patients showed hand stereotypies that coincided with or preceded the loss of purposeful hand movements in 62% of the patients with MECP2 mutations. The hair pulling stereotypy was more frequent in the group with detected mutations, whereas hand washing was not. Hand gaze was absent in all RTT patients with MECP2 mutations. Patients with MECP2 mutations also had more varied stereotypies, and the number of stereotypies displayed by each patient decreased significantly with age in this group. In all patients, stereotypies other than manual tended to disappear with the evolution of the disease.

CONCLUSIONS

Although symmetric midline hand stereotypies were not specific to patients with an MECP2 mutation, some of the other stereotypies seemed to be more characteristic of this group. In patients younger than 10 years and meeting the necessary diagnostic criteria of Rett syndrome, the association of hand stereotypies without hand gaze, bruxism, and two or more of the other stereotypies seemed to be highly indicative of the presence of an MECP2 mutation.

Two novel CLN5 mutations in a Portuguese patient with vLINCL: insights into molecular mechanisms of CLN5 deficiency

The neuronal ceroid-lipofuscinoses are the most common neurodegenerative disorders in childhood characterized by progressive blindness, epilepsy, brain atrophy, and premature death. Based on the age at onset, disease progression and ultrastructural features three classical (infantile, late-infantile, and juvenile) and three variant late-infantile forms are generally distinguished (Finnish variant, Costa Rican variant, and epilepsy with progressive motor retardation). The Finnish variant late-infantile form has been associated with CLN5 gene defects, with only five mutations described to date. We report a patient with vLINCL/CLN5 who represents the first evidence of the disease in the Portuguese population. Mutational screening revealed the previously described missense mutation c.835G>A (D279N) inherited from the mother, and two novel mutations, c.565C>T (Q189X) and c.335G>C (R112P) from paternal and maternal inheritance, respectively. Based on data here reported: (i) the number of possible mutations in CLN5 gene is now 7; (ii) the CLN5 Portuguese case represents the third description of the disease outside northern Europe; (iii) the CLN5/mRNA expression level reduced to 45% supports the existence of one mRNA non-producing allele, further noticeable at the protein level; (iv) Western blotting data using a specific antibody to human CLN5p provided evidence for the presence of four integral membrane isoforms in human fibroblasts; (v) data from differential expression of CLN2, CLN3, and CLN5 suggest down-regulation of CLN3 gene expression in CLN2 and CLN5-deficient human patients and this observation strengths the hypothesis of functional redundancy of the CLN system.

Dementia care in India: a progress report

According to the 2001 census, India is home to more than 76 million people aged 60 years and over. This age-group, currently only 7.4% of the population, is expected to grow dramatically in the coming few decades. Analysis of the census data shows substantial variation in the rate of demographic ageing across India: at present, 10.5% of Kerala's population is older than 60 years, while in Dadra and Nagarhaveli this proportion is only 4%. Regions with more favourable health indicators seem to be ageing faster and the demand for specialist services will soon be evident in such places. There is a growing realisation that the care of older people with disabilities makes enormous demands on their carers. Terms such as 'dementia' and 'Alzheimer's disease' are now better understood. This was not the case when the Alzheimer's and Related Disorders Society of India (ARDSI) initiated awareness programmes. However, dementia remains a largely hidden problem in those disadvantaged parts of India where poverty and illiteracy remain prevalent.

Toxicological studies in tropical ecosystems: an ecotoxicological risk assessment of pesticide runoff in South Florida estuarine ecosystems

A multiyear study in the C-111 canal system and associated sites in Florida Bay was undertaken to determine the potential pesticide risk that exists in South Florida. After the examination of extensive pesticide concentration data in surface water, tissues, and semipermeable membrane devices (SPMDs), canal contamination seems to be derived from the extensive agricultural production that drains into the C-111 canal. The results of this study indicate that runoff from agricultural processes led to quantifiable pesticide residues in both canal and bay surface water, which occasionally exceeded current water quality criteria. The major pesticide of concern was endosulfan, which was detected at 100% of the sites sampled. Endosulfan exposure did not cause any acute effects in fish and crustaceans deployed in field bioassays. Chronic effects were observed in copepods, clams, and oysters but could not be attributed to endosulfan exposure. The decision to alter the C-111 canal flow and allow increased freshwater flow into the adjacent Everglades National Park may result in discharges of pesticides into the Everglades. Continued monitoring in this area is needed during this change in flow regime.

Low frequency noise and whole-body vibration cause increased levels of sister chromatid exchange in splenocytes of exposed mice

Chronic exposure to low frequency (LF) noise and whole-body vibration (WBV) induces both physiological and psychological alterations in man. Recently, we have shown that long-term occupational exposure to LF noise and WBV produces genotoxic effects in man expressed as an increase in sister chromatid exchange (SCE) levels in lymphocytes. The objectives of the present study were to investigate whether the observed effect could be reproduced in a murine model and, if so, which of the agents, LF noise alone or in combination with WBV, would be instrumental in the SCE induction. SCEs were analyzed in spleen lymphocytes of mice exposed to LF noise alone and in combination with WBV for 300 and 600 hr. An effect at the cell cycle kinetics level was also investigated. The results revealed significant increases in the mean SCE number per cell and in the proportion of cells with high frequency of SCEs (HFCs) in lymphocytes of mice submitted to combined noise and WBV over controls. No significant differences were found between single noise-exposed and control mice. A cell cycle delay was observed exclusively in the noise and WBV exposure groups. In conclusion, we demonstrated that, as in exposed workers, prolonged exposure to the combination of LF noise and WBV determines an increase in SCE level in mice while LF noise alone is not effective in SCE induction.

Digital image documentation for quality assessment

OBJECTIVE

To demonstrate the feasibility of the use of digital images to document routine cases and to perform diagnostic quality assessment.

METHODS

Pathologists documented cases by acquiring up to 12 digital images per case. The images were sampled at 25:1, 50:1, 100:1, 200:1, or 400:1 magnifications, according to adequacy in aiding diagnosis. After each acquisition, the referral pathologist marked a region of interest within each acquired image in order to evaluate intrinsic redundancy. The extrinsic redundancy was determined by counting the unnecessary images. Cases were randomly selected and reviewed by one pathologist. The quality of each image, the possibility of accomplishing a diagnosis based on images, and the degree of agreement was evaluated.

RESULTS

During routine practice, 1469 cases were documented using 3902 images. Most of the images were acquired at higher power magnifications. From all acquired cases, 143 cases and their 373 related images were randomly selected for review. In 88.1% (126/143) of reviewed cases, it was possible to accomplish the diagnosis based on images. In 30.2% (38/126) of these cases, the reviewer considered that the diagnosis could be accomplished with fewer images. The referral pathologist and the reviewer found intrinsic redundancy in 57.8% and 54.5% of images, respectively.

CONCLUSIONS

Our results showed that digital image documentation to perform diagnostic quality assessment is a feasible solution. However, owing to the impact on routine practice, guidelines for acquisition and documentation of cases may be needed.

Fetal adenomas and minimally invasive follicular carcinomas of the thyroid frequently display a triploid or near triploid DNA pattern

The ploidy pattern and the percentage of S-phase cells were investigated by means of flow cytometry using fresh or frozen samples in a series of 143 tumors and tumor-like lesions of the thyroid in an attempt to find whether there is any relationship between the histological characteristics of the lesions and their DNA content. The percentages of aneuploidy cases per category were: nodular goiter, 18.5% (15/81); fetal adenoma (including cases with trabecular/solid growth pattern), 58.3% (14/24); follicular adenoma other than fetal adenoma, 0% (0/18); papillary carcinoma, 11.1% (1/9); and minimally invasive follicular carcinoma, 57.1% (4/7). Regardless of the histological category, aneuploid lesions had a significantly higher (P < 0.001) percentage of S-phase cells (7.3%) than diploid lesions (4.1%). All the six cases with a DNA content within the triploid range were fetal adenomas, but one was a follicular carcinoma displaying a fetal adenoma-like growth pattern. The other three follicular carcinomas with an aneuploid DNA pattern also displayed foci of fetal adenoma-like growth pattern. Image cytometry of the four aneuploid follicular carcinomas showed similar DNA indexes in the peripheral, invasive foci of the lesions and in the central fetal adenoma-like areas. These results demonstrate that aneuploidy in benign tumors is restricted to adenomas displaying a fetal or fetal/embryonal growth pattern and support the concept that chromosome instability is a major pathway of tumorigenesis in thyroid follicular neoplasms.

Microvessel density counting in breast cancer. Slides vs. digital images

OBJECTIVE

To develop a program to assist the pathologist in the acquisition and evaluation of digital images to determine microvessel density (MVD) in tissues.

STUDY DESIGN

Ten cases of breast cancer with a high degree of neovascularization were selected. A standard immunohistochemical method was used to highlight the microvessels (monoclonal anti-factor VIII, avidinbiotin-peroxidase complex method). Two pathologists (one senior [S] and one junior [J]) evaluated four areas of highest neovascularization ("hot spots") in the tumors. Microscopically MVD was determined in four chosen areas (400:1). From the center of each area two digital images were acquired at a magnification of 200:1. All counts made by microscopic observation were compared with those made on the digital images. To compare MVD counting at different resolution, two sets of images at different sampling densities (320 x 240 and 1,600 x 1,200) were assessed by the two pathologists.

RESULTS

We obtained a good correlation (r = .98 for S and .96 for J) between the MVD counts obtained at the microscope (192.8 MV/mm2 [mean of S] and 181.8 MV/mm2 [mean of J]) and the MVD counts from digital images (153.2 MV/mm2 [mean of S] and 171.0 MV/mm2 [mean of J]) at high resolution. The counts were lower for digital images at lower sampling density (125.0 MV/mm2 [mean of S] and 78.2 MV/mm2 [mean of J]). With low-resolution digital images only S maintained a good correlation (r = .96 for S and .34 for J) with the microscopic evaluation of MVD. Interobserver analysis showed a good correlation (r = .82 for the microscope and r = .78 for the digital images) of MVD evaluated either at the microscope or in high-resolution digital images.

CONCLUSION

We demonstrated the functionality and usefulness of our program in performing MVD evaluation. Considering the capabilities of the program to store all images and microvessel marks and the reliability of MVD evaluation based on digital images, we consider this program the first step toward fully automated MVD assessment.

Ancestral origins of the Machado-Joseph disease mutation: a worldwide haplotype study

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder originally described in families of Portuguese-Azorean ancestry. The cloning of the MJD1 gene allowed identification of the disease in many other populations, and MJD is now known to be the most common cause of dominant spinocerebellar ataxia. The hypothesis that its present world distribution could result from the spread of an original founder mutation has been raised, both at historical and molecular levels. In the present study, we tested this hypothesis by linkage-disequilibrium analysis of tightly linked polymorphisms and by haplotype comparison, in 249 families from different countries. We typed five microsatellite markers surrounding the MJD1 locus (D14S1015, D14S995, D14S973, D14S1016, and D14S977), and three intragenic single-base-pair polymorphisms (A(669)TG/G(669)TG, C(987)GG/G(987)GG, and TAA(1118)/TAC(1118)). The results show two different haplotypes, specific to the island of origin, in families of Azorean extraction. In families from mainland Portugal, both Azorean haplotypes can be found. The majority of the non-Portuguese families also share the same intragenic haplotype seen in the families coming from the island of Flores, but at least three other haplotypes were seen. These findings suggest two introductions of the mutation into the Portuguese population. Worldwide, the sharing of one intragenic haplotype by the majority of the families studied implies a founder mutation in MJD.

Evidence for an involvement of vitellogenin in the steroidogenic activity of rainbow trout (Oncorhynchus mykiss) vitellogenic oocytes

In vivo and in vitro the concentration of vitellogenin (VTG) inside the oocyte can alter VTG production by the liver, modulating the synthesis of 17beta-estradiol (E(2)) by the ovary. To gain a greater insight into this mechanism, the in vitro production of free and conjugated testosterone (T), E(2), and androstenedione (A) by rainbow trout oocytes from the early and middle vitellogenic stage was measured by radioimmunoassay. There was a decreased E(2) production that was greater in September (40%) than October (30%), by the oocytes incubated with the vitellogenic fraction. The production of E(2) conjugated as glucuronide was lower than sulfate (P < 0.05), but similar in control and VTG-incubated oocytes. Levels of free T increased from September to October, and conjugates were both produced at low levels, and no differences were detected between control and incubated VTG oocytes. The decreased synthesis of E(2) by oocytes incubated with VTG was not followed by an increase in the amount of T or conjugated E(2), because there were no differences under the two circumstances. However, there was a reduced synthesis of A with oocytes producing low levels of E(2). These results suggest that the presence of high levels of VTG in the oocyte suppresses the synthesis of A and E(2), affecting the activities of the enzymes C17,20 lyase and aromatase and probably interfering with the heme protein cytochrome P450 which in the ovary catalyses C 17,20 lyase (P450 c17) and aromatase (P450 arom).

[Evaluation of the prognostic value of cardiac troponin i in patients with unstable angina]

OBJECTIVE

The purpose of this study was to evaluate the in-hospital and follow-up prognostic value of cardiac troponin I in patients admitted in the Coronary Care Unit and discharged with the diagnosis of unstable angina.

POPULATION AND METHODS

118 patients were admitted in the Coronary Care Unit, discharged with the diagnosis of unstable angina with a follow-up of 13.5 months. Cardiac Troponin I (cTnI) was measured on admission, 4 and 12 hours later. For the purposes of the study, we chose a cut-off value of 0.4 ng/mL as the minimal acceptable concentration of cTnI. The patients were divided in two groups: Group A (n = 82) if all measurements with cTnI < or = 0.4 ng/mL and Group B (n = 36) if any measurement with cTnI > 0.4 ng/mL. In both groups, multiple coronary events during hospitalisation and follow-up were evaluated: death; acute myocardial infarction; angina; hospitalisation; coronary surgery or angioplasty; and also the severity of coronary artery disease and the number of patients without coronary events. The results were compared by the Student's unpaired t-test and by chi-square test.

RESULTS

Age, sex and vascular risk factors were similar in both groups. There was a statistically significant increase in angina and coronary surgery with increasing levels of cardiac troponin I (Group B) (13 vs 5, p < 0.0001), multiple vessel disease (16 vs 18, p < 0.0008) and myocardial infarction (12% vs 0%, p < 0.03). Sixty patients had no coronary events in Group A compared to thirteen in Group B (p < 0.0001). There were no significant differences between the groups with respect to hospitalisation and angioplasty (17% in Group B vs 7% in Group A) and death (3% vs 0%).

CONCLUSIONS

In this population with unstable angina, cardiac troponin I level greater than 0.4 ng/mL measured in the 12 hours after admission provides useful prognostic information. It permits the early identification of patients with an increased risk of in-hospital and follow-up cardiac events and could be correlated with the severity of coronary artery disease.

[Angioplasty with stenting in single vessel disease: non invasive methods for detecting restenosis]

OBJECTIVE

To compare the value of the myocardial perfusion imaging with 99Tc sestamibi (MIBI) with clinical data and stress EKG (SEKG) variables, in the detection of angiographic restenosis (AR: lesion > 50%), in a group of patients (pts) with single vessel disease (angiographic lesion above 70% in one epicardial artery), submitted to coronary angioplasty (PTCA) with stenting.

POPULATION AND METHODS

Fifty-nine pts, followed prospectively, (49 males and 10 females aged 57 +/- 10) were submitted to 61 angioplasties, with dilatation of 59 vessels, and with stenting in 63 (1.07 stent/vessel). Clinical evaluation was performed in the first, third and sixth month, SEKG with MIBI in the fourth month and recatheterization for angiographic control in the sixth month. The pts were divided in two groups: R-positive angiographic restenosis (AR)--14 pts: NR--without AR--45 pts; the angiographic restenosis rate was 23.7%. The patients' history, cause of admission, procedure characteristics, medication at discharge, clinical events during follow-up, variables of stress EKG associated with myocardial perfusion and angiographic control were analyzed.

RESULTS

The cause of admission was the same in both groups (MI in R group: 28.6%; NR: 46.7%; p = ns). There was no difference in the discharge medication. The R group was more symptomatic (Angina: R = 50.0% vs NR = 11.1%; p < 0.001 clinical restenosis rate = 11.8%), and had more revascularization procedures (PTCA: R = 57.1% vs NR = 2.8%; p < 0.001/Bypass surgery: R = 14.3% vs NR = 0%; p = 0.01). This group had abnormal stress EKG more frequently (42.9 vs 20.0%, p = ns) and ischemia in the myocardial perfusion scintigraphy (57.1 vs 6.7% p < 0.001). [table: see text]

CONCLUSION

The clinical and diagnostic tests evaluated in this study showed a limited sensitivity in the detection of angiographic restenosis in a group of patients with single vessel disease submitted to coronary angioplasty and stenting. Myocardial scintigraphy was the best method for the detection of angiographic restenosis, showing a high specificity and a reasonable sensitivity.

Increased levels of sister chromatid exchanges in military aircraft pilots

Sister chromatid exchanges (SCEs) were scored in lymphocytes of nine high-performance pilots of alphajet aircrafts and of ten control individuals from the same air base. Statistical analysis of the mean SCE count per cell in the total number of cells analyzed as well as in those having 12 or more SCEs (high-frequency cells, HFCs) revealed a significant difference between pilots and controls, after adjusting for the effect of smoking. Analysis of the cell cycle kinetic data (replication and mitotic indices) revealed no significant differences either between pilots and controls or between smokers and nonsmokers. Previously, we reported an increase in the SCE levels in workers of the aeronautical industry exposed to noise and whole-body vibration. The present results corroborate those findings and indicate that noise and whole-body vibration may cause genotoxic effects in man.

Sister chromatid exchange analysis in workers exposed to noise and vibration

BACKGROUND

There has been a growing interest in the combined effects of noise and vibration. In a population of aeronautical workers diagnosed with vibroacoustic disease (VAD), a large incidence of malignancy was detected. These workers were exposed to large pressure amplitude (LPA) (> or = 90 dB SPL) noise, with energy content concentrated within the low frequency (LF) bands (< or = 500 Hz) and whole-body vibration (WBV). To our knowledge, there are no studies conducted in humans or animals that address the issue of the potential genotoxic effects of vibration combined with noise. In the present study, the levels of sister chromatid exchanges (SCE) and of cells with high frequencies of SCE (HFC) were analyzed in peripheral blood lymphocytes of workers employed in various occupations within the aeronautical industry.

METHODS

SCE and HFC were analyzed in lymphocytes of 50 workers occupationally exposed to noise and vibration and of 34 office-worker controls (G0). The exposed group included: 10 hand-vibrating tool operators (G1), 15 engine test cell technicians (G2), 12 aircraft run-up technicians (G3) and 13 Portuguese Air Force helicopter pilots (G4). Groups 2-4 were exposed to WBV and LPALF noise; group 1 was exposed to LPA high frequency noise and local vibration. Statistical analysis of the mean SCE count per cell was carried out by multiple regression analysis comparing various predictor variables: type of exposure, duration of exposure, age, and cigarette consumption.

RESULTS

Only cigarette consumption and type of exposure were found to be significantly correlated with the mean SCE frequency. After allowing for the effects of smoking, the analysis indicates that: 1) there was no significant difference between G1 and G0 (p > 0.05); 2) the differences between G2 and G0, G3 and G0, G4 and G0 were all highly significant (p < 0.001); 3) there was no significant difference between G2 and G3 (p > 0.05), nor between G2 and G3 combined and G4 (p > 0.05); and 4) G2 and G4 combined had a significantly elevated mean SCE frequency compared G0 (p < 0.001). Statistical analysis of the proportion of HFC was consistent with these results.

CONCLUSION

Our data suggest that occupational exposure to LPALF noise and WBV may lead to increased levels of SCE in men. These results also suggest a reason for the high incidence of malignancy in VAD patients. The observed effects may not reflect a direct action of these physical agents on DNA. Alternative explanations may lie in the noise-, vibration-, and/or stress-induced pathophysiological changes.

Study of three intragenic polymorphisms in the Machado-Joseph disease gene (MJD1) in relation to genetic instability of the (CAG)n tract

Intergenerational instability is one of the most important features of the disease-associated trinucleotide expansions, leading to variation in size of the repeat among and within families, which manifests as variable age at onset and severity, and is probably the basis for the occurrence of anticipation. Several factors are known to affect the degree of instability, namely the type of repeated sequence, its initial size, the presence or absence of interruptions in the repetitive tract and the gender of the transmitting parent. A recent study demonstrated the effect of an intragenic polymorphism (C987GG/G987GG) in the Machado-Joseph disease causative gene, immediately downstream of the CAG repeat, on the intergenerational instability of the expanded repeat. Surprisingly, there was an effect not only of the specific allele in cis to the disease chromosome, but also of the allele on the normal chromosome, suggesting the existence of an interaction between the normal and expanded alleles that affects the fidelity of replication of the (CAG)n tract. This effect could be a direct effect of the polymorphism studied or, alternatively, this polymorphism could be in disequilibrium with some other flanking sequence which affects the instability of the repetitive (CAG)n tract. In order to confirm the previous results in a different population and to distinguish between a direct and indirect effect of the CGG/GGG polymorphism, we typed 70 parent-progeny pairs for which the variation in the (CAG)n length in the MJD1 gene was known, for three intragenic polymorphisms: C987GG/G987GG and two additional, newly described ones, TAA1118/TAC1118 and A669TG/G669TG. We also typed a control population of 125 individuals for the A669TG/G669TG, C987GG/G987GG and TAA1118/TAC1118 polymorphisms, in an attempt to identify any association between haplotype and (CAG)n length in normal chromosomes, suggestive of an instability-predisposing effect of the repeat-flanking sequences, which could have led to the origin of the MJD mutation in the human population. We confirmed the effect of the C987GG/G987GG polymorphism on intergenerational instability when present in trans. Our results suggest that this effect is restricted to a small region of the gene, immediately downstream of the CAG repeat, which includes this particular nucleotide substitution and the stop codon of the MJD1 cDNA, and is not a more widespread chromosomal effect. The lack of a significant association of any specific intragenic haplotype with larger CAG repeats in normal chromosomes, together with the absence of an effect of the intragenic haplotype in cis on the intergenerational instability of the expanded (CAG)n in MJD families does not indicate the existence of an instability-predisposing haplotype.

Analysis of SCA1, DRPLA, MJD, SCA2, and SCA6 CAG repeats in 48 Portuguese ataxia families

The spinocerebellar ataxias (SCAs) are clinically and genetically a heterogeneous group of neurodegenerative disorders. To date, eight different loci causing SCA have been identified: SCA1, SCA2, Machado-Joseph disease (MJD)/SCA3, SCA4, SCA5, SCA6, SCA7, and dentatorubropallidoluysian atrophy (DRPLA). Expansion of a CAG repeat in the disease genes has been found in five of these disorders. To estimate the relative frequencies of the SCA1, DRPLA, MJD, SCA2, and SCA6 mutations among Portuguese ataxia patients, we collected DNA samples from 48 ataxia families and performed polymerase chain reaction (PCR) amplification of the CAG repeat mutations on chromosomes 6p, 12p, 14q, 12q, and 19p, respectively. Fifty-five individuals belonging to 34 dominant families (74%) had an expanded CAG repeat at the MJD gene. In five individuals from two kindreds with a dominant pattern of inheritance (4%), an expanded CAG repeat at the SCA2 gene was found. In MJD patients, the normal allele size ranged from 13 to 41, whereas the mutant alleles contained 65 to 80 repeats. For the SCA2 patients, normal alleles had 22 or 23, while expanded alleles had between 36 and 47 CAG units. We did not find the SCA1, DRPLA, or SCA6 mutations in our group of families. The MJD mutation remains the most common cause of SCA in Portugal, while a small number of cases are caused by mutations at the SCA2 gene, and 22% are due to still unidentified genes.

Sister chromatid exchange analysis in workers exposed to noise and vibration

Workers chronically exposed to whole-body vibration and noise are known to develop pathophysiological and psychological disturbances. The frequencies of sister chromatid exchanges (SCEs) and of cells with high frequencies of SCEs (HFCs) were analyzed in lymphocytes of 50 workers occupationally exposed to vibration and noise and of 34 controls. The exposed group included: individuals operating hand-vibrating tools (group 1), 'test-cell operators' (group 2) and 'run-up' operators (group 3) from an air base and helicopter pilots (group 4). The statistical analysis of the mean SCE count per cell was carried out by multiple regression analysis, comparing various predictor variables: exposure group, duration of exposure, age and cigarette consumption. Only cigarette consumption and exposure group were found to be significantly correlated with the mean SCE frequency. After allowing for the effects of smoking, the analysis indicates that: (1) there was no significant difference between group 1 and controls (p > 0.05); (2) the differences between group 2 and group 0, group 3 and group 0 and group 4 and group 0 were all highly significant (p < 0.001); (3) there was no significant difference between groups 2 and 3 (p > 0.05), nor between groups 2 and 3 combined and group 4 (p > 0.05); (4) exposure groups 2, 3 and 4 combined, had a significantly elevated mean SCE frequency compared to the control group (p < 0.0001). Statistical analysis of the proportion of HFCs was consistent with these results. Our data suggest that chronic exposure to whole-body vibration and noise may lead to an increase in the level of SCEs in man. The observed effects may not reflect a direct action of these physical agents on DNA. Alternative explanations may include some of the whole-body vibration and noise-induced or stress-induced pathophysiological alterations which may indirectly induce SCE formation.

Dose dependence of radiation-induced micronuclei in cytokinesis-blocked human lymphocytes

Following selection of appropriate culture conditions, various experiments were conducted to evaluate the suitability of the micronucleus assay in cytokinesis-blocked lymphocytes for biological dosimetry purposes. A dose-effect relationship was determined, based on the frequency of micronuclei induced by various doses of 60Co gamma-rays. The data were best fitted to a linear-quadratic model. To validate the system, an attempt was made to estimate unknown dose levels from the yield of micronuclei, by inverting the derived dose-response function. It was concluded that the assay provides a valid approach for dose assessment. The size of radiation-induced micronuclei was measured in relation to the dose. A significant difference in the proportion of large micronuclei between high and low doses was observed. The chromosomal composition of micronuclei, detected by immunofluorescent staining of kinetochores, showed that only a small proportion of micronuclei contains kinetochore. The possible contribution of various mechanisms for the formation of large radiation-induced micronuclei is discussed.

Xylanolytic enzyme production by an Aspergillus niger isolate

Production of xylanolytic enzymes by an Aspergillus niger CCMI 850 isolate was investigated in batch cultures. The effect of the composition of a fermentation medium that did not include chemical inducers, on beta-xylanase, beta-xylosidase, alpha-L-arabinofuranosidase, and total cellulase activity was studied. With 4% xylan as the carbon source, about 65 U/mL of beta-xylanase was obtained, whereas the total cellulase activity was undetectable, under the specified conditions. This beta-xylanase activity represents the highest reported for a wild-type strain of A. niger. The effect of pH and temperature on the activity of beta-xylanase was studied. Partial characterization of the beta-xylanase showed that with insoluble birchwood as substrate the Km and Vmax were 0.3 mM and 19 mumol/min, respectively. Aspects of using the crude beta-xylanase preparation for applications in the pulp and paper industry were discussed.