Synergistic neurotoxicity of carbon tetrachloride/carbon disulfide (80/20 fumigants) and other pesticides in grain storage workers

Neurophysiologic, neurobehavioral, and neuropsychologic profiles in 17 grain storage workers, 1 grain inspector, and 4 malting laboratory workers are described. The effects of CS2 toxicity as seen in viscose rayon workers as well as in experimental animals is remarkably similar to the clinical profile of our grain storage workers. CS2 use explains the dysfunction of peripheral axons, auditory nerve, the optic nerve, and the extrapyramidal system, as well as altered behavior and cognition changes. The signs and symptoms in these workers seem to be dose-related and we note that workers separated out from the areas where fumigation took place reported improvement not seen by fellow workers who continued the fumigant treatment routine. Likewise, malting laboratory workers exposed only to the grain dust from 3 to 7 years showed only minimal symptoms. Though a number of mechanism have been suggested for the alteration of neuropsychological function, the chelating ability of DDC derived from CS2 and its ability to markedly increase copper and zinc within the central nervous system suggests a mechanism of toxicity analogous to copper intoxication as in Wilson's Disease and may explain the production of extrapyramidal symptoms in these patients. Chelation of copper might prove therapeutic in CS2 poisoning. It is obvious that both basic and clinical research will be necessary to sort out the questions raised. We applaud the EPA's decision to ban the use of 80/20 fumigants and also methyl bromide, and trust that similar toxic substances be carefully studied before their selection for replacing these previous toxic agents. We further decry the technique of re-introducing grain dust into the food chain rather than destroying it, since the dust contains very high residues of fumigant material. We speculate on the possible role of CS2 and other pesticides in the food chain and the incidence of Parkinsonian symptoms in these patients and the general public.

A critical analysis of the benefits and limitations of an applied degree in undergraduate nursing education

The purpose of this paper is to present a critical analysis of the applied degree in nursing as an alternative to collaborative models of undergraduate education delivery by different post-secondary institutions. The notion of having multiple levels of entry into nursing (Northrup et al. 2004) and the authority of colleges to award degrees in nursing (Skolnik 1994) have important practical implications for the profession. Since there is a paucity of Canadian literature about applied degrees in nursing, this paper will make an important contribution to the field of nursing education. Due to the collaborative partnerships that have emerged in many jurisdictions in order to meet the baccalaureate degree as the entry-to-practice requirement, an analysis of the Applied Degree in Nursing is relevant and timely. The paper provides a brief history of the baccalaureate degree as the entry-to-practice requirement for nursing, along with an overview of the rationale for the baccalaureate degree from regulatory, research, academic and practice perspectives. Through an analysis of the benefits, limitations and implications of the applied degree, we conclude that this new applied baccalaureate challenges nursing's status as an academic discipline.

Investigation of retroviral involvement in chronic fatigue syndrome

Within the last few years significant efforts have been made to identify objective reliable diagnostic markers from individuals with chronic fatigue syndrome (CFS). We report the absence of a previously described retroviral marker (HTLV-II gag) in a blinded study of CFS cases. Even with excellent reproducible sensitivities, this marker failed in repeated attempts to distinguish cases from controls. In addition, four other retroviruses (simian T cell leukaemia virus, human spumavirus, bovine leukaemia virus and simian retrovirus) were examined for their presence in these CFS cases and found to be absent. Our findings suggest that these agents, at least as markers, are non-distinguishing for CFS and that other factors may be confounding the resolution of an aetiology to this syndrome.

Inter-Rater Reliability of the Diagnoses of Psychosis and Depression in Individuals with Intellectual Disabilities

BACKGROUND: There is a history of over-prescription of antipsychotics to individuals with intellectual disability (ID), while antidepressants may be under-prescribed. However, appropriate treatment is best supported when the diagnosis of psychosis or depression is valid and carries good predictive validity. The present authors report a study examining one aspect of validity, namely whether skilled clinicians can agree on whether an individual with an ID is psychotic or depressed. MATERIALS AND METHODS: Pairs of clinicians assessed 52 individuals. Agreement was assessed using Cohen's kappa statistic and agreement proportion. RESULTS: Overall agreement was high for both psychosis and depression. Whether the individual had mild ID or moderate/severe ID did not have a significant impact on agreement. CONCLUSIONS: Experienced clinicians achieved a high level of agreement as to whether a person with ID was psychotic or depressed similar to that found for those without ID. The findings provide some support for treatment interventions based on diagnosis.

DNA recognition by the oestrogen receptor: from solution to the crystal

BACKGROUND

The steroid/nuclear hormone receptors are a large family of conserved ligand-activated transcription factors that regulate gene expression through binding to response elements upstream of their target genes. Most members of this family bind to DNA as homodimers or heterodimers and recognize the sequence, spacing and orientation of the two half-sites of their response elements. The recognition and discrimination of the sequence and arrangements of these half-sites are mediated primarily by a highly conserved DNA-binding domain.

RESULTS

Here we describe the DNA-binding properties of the isolated DNA-binding domain of the oestrogen receptor, the ERDBD, and its refined NMR structure. This domain is monomeric in solution, but two molecules bind cooperatively to specific DNA sequences; this cooperativity determines the arrangement of half-sites that is recognized by the ERDBD. The 10 carboxy-terminal residues and a region of 15 residues within the domain are disordered in the solution structure, yet are important for DNA binding.

CONCLUSION

The cooperative nature of ERDBD binding to DNA is important. The previously-determined X-ray structure of the ERDBD dimer bound to DNA shows that the 15 internal residues disordered in solution make contact both with DNA and with the corresponding region of the other monomer. These results suggest that these residues become ordered during the process of binding to DNA, forming the dimer interface and thus contributing to the cooperative interaction between monomers.

Structure of the TRFH dimerization domain of the human telomeric proteins TRF1 and TRF2

TRF1 and TRF2 are key components of vertebrate telomeres. They bind to double-stranded telomeric DNA as homodimers. Dimerization involves the TRF homology (TRFH) domain, which also mediates interactions with other telomeric proteins. The crystal structures of the dimerization domains from human TRF1 and TRF2 were determined at 2.9 and 2.2 A resolution, respectively. Despite a modest sequence identity, the two TRFH domains have the same entirely alpha-helical architecture, resembling a twisted horseshoe. The dimerization interfaces feature unique interactions that prevent heterodimerization. Mutational analysis of TRF1 corroborates the structural data and underscores the importance of the TRFH domain in dimerization, DNA binding, and telomere localization. A possible structural homology between the TRFH domain of fission yeast telomeric protein Taz1 with those of the vertebrate TRFs is suggested.

Outbreak of vancomycin-resistant Enterococcus faecium in a neonatal intensive care unit

An outbreak of vancomycin-resistant Enterococcus faecium involving 28 infants in a neonatal intensive care unit was observed. Successful control of the outbreak was achieved following use of patient and staff cohorting, contact isolation precautions, patient and environmental surveillance cultures, environmental decontamination, molecular typing, introduction of an alcohol-based hand disinfectant, and decreased use of vancomycin.

Specific interactions of the telomeric protein Rap1p with nucleosomal binding sites

The telomeres of Saccharomyces cerevisiae are structurally and functionally well characterized. Their telomeric DNA is packaged by the protein Rap1p (repressor activator protein 1). Rap1p is a multifunctional, sequence-specific, DNA-binding protein which, besides participating in the regulation of telomeres structure and length, is also involved in transcriptional regulation of genes essential for cell growth and in silencing. Whereas the long tracts of telomeric DNA repeats of higher eukaryotes are mostly organized in closely spaced canonical nucleosomal arrays, it has been proposed that the 300 base-pairs of S. cerevisiae telomeric DNA are organized in a large non-nucleosomal structure that has been called the telosome. Recently, nucleosomes have been found also in Tetrahymena thermophila telomeres, suggesting that, in general, telomere structural differences between lower and higher eukaryotes could be quantitative, rather than qualitative. Using an in vitro model system, we have addressed the question of whether Rap1p can form a stable ternary complex with nucleosomes containing telomeric binding sites, or competes with nucleosome core formation. The approach we have taken is to place a single Rap1p-binding site at different positions within a nucleosome core and then test the binding of Rap1p and its DNA-binding domain (Rap1p-DBD). We show here that both proteins are able to specifically recognize their nucleosomal binding site, but that binding is dependent on the location of the site within the nucleosome core structure. These results show that a ternary complex between a nucleosome and Rap1p is stable and could be a possible intermediate between telomeric nucleosomes and telosomes in the dynamics of S. cerevisiae telomere organization.

Neural correlates of recovery from aphasia after damage to left inferior frontal cortex

OBJECTIVE

To determine neural correlates of recovery from aphasia after left frontal injury.

METHODS

The authors studied the verbal performance of patients with infarcts centered in the left inferior frontal gyrus (IFG), using a battery of attention-demanding lexical tasks that normally activate the left IFG and a simpler reading task that does not normally recruit the left IFG. The authors used positron emission tomography (PET) and functional MRI (fMRI) to record neural activity in the same group of patients during word-stem completion, one of the attention-demanding lexical tasks. To identify potential neural correlates of compensation/recovery, they analyzed the resulting data for the group as a whole (PET, fMRI) and also for each participant (fMRI).

RESULTS

Patients with damage to the left IFG were impaired on all attention-demanding lexical tasks, but they completed the word-reading tasks normally. The imaging studies demonstrated a stronger-than-normal response in the right IFG, a region homologous to the damaged left IFG. The level of activation in the right IFG did not correlate with verbal performance, however. In addition, a perilesional response within the damaged left IFG was localized in the two patients who gave the best performance in the word-stem completion task and showed the most complete recovery from aphasia.

CONCLUSIONS

Right-IFG activity may represent either the recruitment of a preexisting neural pathway through alternative behavioral strategies or an anomalous response caused by removal of the left IFG. Perilesional activity in the left IFG may represent sparing or restoration of normal function in peri-infarctual tissue that was inactive early on after injury. This activity may be of greater functional significance than right IFG activity because it was associated with more normal verbal performance.

The influence of nutrition on methyl mercury intoxication

This article reviews progress in the research of methyl mercury (MeHg) and nutrient interactions during the past two decades. Special emphasis is placed on the following three major areas: a) effects on kinetics, b) effects on toxicity, and c) possible mechanisms. Dietary information is not usually collected in most epidemiologic studies examining of the effects of MeHg exposure. However, inconsistency of the MeHg toxicity observed in different populations is commonly attributed to possible effects of dietary modulation. Even though the mechanisms of interaction have not been totally elucidated, research in nutritional toxicology has provided insights into the understanding of the effects of nutrients on MeHg toxicity. Some of this information can be readily incorporated into the risk assessment of MeHg in the diets of fish-eating populations. It is also clear that there is a need for more studies designed specifically to address the role of nutrition in the metabolism and detoxification of MeHg. It is also important to collect more detailed dietary information in future epidemiologic studies of MeHg exposure.

Simian foamy virus infection among zoo keepers

We investigated 322 North American zoo workers in an anonymous serosurvey for antibodies to simian foamy viruses to establish the potential risk of zoonotic transmission by these retroviruses. 4 of 133 (3%) individuals who worked specifically with mammals including primates were seropositive, primarily with chimp-like viruses, indicating the importance of work practices to reduce exposure to these agents.

Distance learning for post-registered nursing: the facts

AIM

To explore nurses' perceptions and evaluate the potential of distance learning as a method of teaching for post-registered nurses working in the community.

METHOD

The study used open-ended questions in focus groups. Each group consisted of nine students each with an interest in post-registration learning. The interviews were taped and transcribed (n = 18).

RESULTS

The respondents saw distance learning as a necessary way of updating their knowledge, as long as the education provided was relevant to their practice. They also saw this method of learning as an opportunity to take responsibility for their own learning. There was a conflict of opinion, however, as some respondents felt the courses to be a flexible way to teach and learn, while others found the courses to be too focussed and not necessarily relevant.

CONCLUSION

The study provides an insight into distance learning and what some post-registered nurses perceive to be important factors associated with it as a method of teaching. It suggests that post-registered nurses working in the community will benefit from distance learning as a method of teaching.

Localization of a putative transcriptional regulator (ATRX) at pericentromeric heterochromatin and the short arms of acrocentric chromosomes

ATRX is a member of the SNF2 family of helicase/ATPases that is thought to regulate gene expression via an effect on chromatin structure and/or function. Mutations in the hATRX gene cause severe syndromal mental retardation associated with alpha-thalassemia. Using indirect immunofluorescence and confocal microscopy we have shown that ATRX protein is associated with pericentromeric heterochromatin during interphase and mitosis. By coimmunofluorescence, ATRX localizes with a mouse homologue of the Drosophila heterochromatic protein HP1 in vivo, consistent with a previous two-hybrid screen identifying this interaction. From the analysis of a trap assay for nuclear proteins, we have shown that the localization of ATRX to heterochromatin is encoded by its N-terminal region, which contains a conserved plant homeodomain-like finger and a coiled-coil domain. In addition to its association with heterochromatin, at metaphase ATRX clearly binds to the short arms of human acrocentric chromosomes, where the arrays of ribosomal DNA are located. The unexpected association of a putative transcriptional regulator with highly repetitive DNA provides a potential explanation for the variability in phenotype of patients with identical mutations in the ATRX gene.

Marked improvement in asthma after Lap-Band surgery for morbid obesity

BACKGROUND

Asthma and morbid obesity are common chronic conditions that may be related. Laparoscopic banding provides effective weight control of morbid obesity. The aim of this study was to evaluate the prevalence of asthma in the morbidly obese and the changes in asthma after laparoscopic adjustable gastric banding (LAGB) (Lap-Band) surgery for morbid obesity.

METHODS

Asthma was assessed preoperatively in all patients presenting for LAGB. 32 consecutive asthmatic patients were followed up clinically and by a standard questionnaire at least 12 months after surgery, and any change in asthma impact was recorded.

RESULTS

The prevalence of the doctors' diagnosis of asthma was 24.6% (73 of 296 consecutive patients). This was significantly higher than the prevalence in the Australian community of 12% to 13% (P < 0.001). The 32 patients who were followed up had a mean body weight of 125.2 kg and a body mass index (BMI) of 45.7 kg/m2 prior to operation, and a weight of 89.3 kg (BMI 32.9 kg/m2) at follow-up. All 32 patients recorded a lower asthma score postoperatively. There were significant improvements in all aspects of asthma assessed. These included severity, daily impact, medications needed, hospitalization, sleep, and exercise. The mean preoperative scaled asthma score was 44.5 +/- 16. There was a highly significant reduction at follow-up to a mean value of 14.3 +/- 11 (P < 0.001).

CONCLUSIONS

There is a high prevalence of asthma in morbidly obese adults, and major reductions in asthma severity occur after Lap-Band(r) surgery and weight loss. Mechanisms other than direct weight loss appear to play a part in this improvement. Prevention of gastroesophageal reflux may be an important factor.

Polymerase chain reaction assays for the diagnosis of infection with the porcine endogenous retrovirus and the detection of pig cells in human and nonhuman recipients of pig xenografts

BACKGROUND

Pigs offer an unlimited source of xenografts for humans. However, recipients of pig xenografts are inevitably exposed to the porcine endogenous retrovirus (PERV), which is carried in the pig germline. The ability of PERV to infect human cells in vitro has heightened safety concerns regarding the transmission of PERV to pig xenograft recipients.

METHODS

In response to the need to establish laboratory tests for the surveillance of PERV infection, we have developed polymerase chain reaction (PCR) assays to detect PERV pol and gag sequences by using conserved primers and probes. In addition, we have developed a PCR assay to detect pig-specific mitochondrial DNA (mtDNA) sequences as a marker of pig cells.

RESULTS

Analysis of assay sensitivities using cloned target copies in a background of human DNA demonstrated a detection threshold of 1, 5, and 1 copy for the PERV gag, pol, and pig mtDNA PCR assays, respectively. All three PCR assays gave negative results on peripheral blood lymphocyte samples from 69 humans, as well as 6 baboons and 6 macaques, demonstrating 100% specificity. The PERV and pig mtDNA assays were integrated into a simple testing algorithm that allows the differentiation between pig cell microchimerism and true xenogeneic infection. To allow for monitoring of PERV expression, a reverse transcriptase-PCR assay was also developed to detect cell-free PERV RNA.

CONCLUSION

The use of the diagnostic tests described here will help define the risks of PERV transmission associated with the use of pig xenografts in humans and nonhuman primates.

Saponins and phenolic content in plant dietary additives of a traditional subsistence community, the Batemi of Ngorongoro District, Tanzania

Reports of plants added to milk and meat-based soups by the Maasai and Batemi in East Africa support a role for phenolic antioxidants and hypocholesterolemic agents in the diet, and provide explanation of the low incidence of cardiovascular disease of populations that traditionally consume high levels of dietary fat and cholesterol. Plant food additives used by the Batemi of Ngorongoro District, Tanzania, were tabulated, based on interviews with 22 informants, while 17 specimens were collected in the field and analyzed for saponin and phenolic content. A total of 81% of the Batemi additives and 82% of those known to be used by the Maasai contain potentially hypocholesterolemic saponins and/or phenolics.

Effects of psycho-educational interventions on sexual health risks and psycho-social adaptation in young adults with genital herpes

The purpose of this study was to test the outcomes of group psycho-educational intervention (PEI) led by nurses on sexual health risks (knowledge, behaviour, disease burden) and psycho-social adaptation (depression, mood states, self-efficacy) in young adults with the chronic disease, genital herpes. Two hundred and fifty-two young adults with symptomatic genital herpes participated in a randomized controlled trial (RCT). The intervention was participation in a three-session group PEI facilitated by a nurse in the community. Participants completed questionnaires measuring sexual health risks (herpes knowledge, sexual risk behaviour, disease burden of patterns of recurrences of outbreaks of the disease), and psycho-social adaptation (depression using the Beck Depression Inventory [BDI], mood states using the Profile of Mood States [POMS], and feelings of self-efficacy for protection from sexually transmitted diseases [PSTD]) at induction into the study, and at 3 and 6 months. Participants were mainly employed, Caucasian, single women in their twenties (X = 27.1 years, SD = 4.3), with some college education; 23% of the sample were men. After controlling for baseline knowledge about genital herpes, the experimental group had significantly more knowledge than the control group at 3 and 6 months' post-intervention. They also reported using condoms and spermicides to prevent the spread of genital herpes more often than did the control group. The implications for nurses in the community include the following: (a) PEI is an intervention that can be used by nurses in the community with a high-risk population; (b) group intervention is a viable treatment for people with a highly stigmatized, chronic sexually transmitted disease (STD); and (c) further testing of the use of PEI by nurses in the community with other high-risk populations is needed.