Microsatellite markers reveal a spectrum of population structures in the malaria parasite Plasmodium falciparum

Multilocus genotyping of microbial pathogens has revealed a range of population structures, with some bacteria showing extensive recombination and others showing almost complete clonality. The population structure of the protozoan parasite Plasmodium falciparum has been harder to evaluate, since most studies have used a limited number of antigen-encoding loci that are known to be under strong selection. We describe length variation at 12 microsatellite loci in 465 infections collected from 9 locations worldwide. These data reveal dramatic differences in parasite population structure in different locations. Strong linkage disequilibrium (LD) was observed in six of nine populations. Significant LD occurred in all locations with prevalence <1% and in only two of five of the populations from regions with higher transmission intensities. Where present, LD results largely from the presence of identical multilocus genotypes within populations, suggesting high levels of self-fertilization in populations with low levels of transmission. We also observed dramatic variation in diversity and geographical differentiation in different regions. Mean heterozygosities in South American countries (0.3-0.4) were less than half those observed in African locations (0. 76-0.8), with intermediate heterozygosities in the Southeast Asia/Pacific samples (0.51-0.65). Furthermore, variation was distributed among locations in South America (F:(ST) = 0.364) and within locations in Africa (F:(ST) = 0.007). The intraspecific patterns of diversity and genetic differentiation observed in P. falciparum are strikingly similar to those seen in interspecific comparisons of plants and animals with differing levels of outcrossing, suggesting that similar processes may be involved. The differences observed may also reflect the recent colonization of non-African populations from an African source, and the relative influences of epidemiology and population history are difficult to disentangle. These data reveal a range of population structures within a single pathogen species and suggest intimate links between patterns of epidemiology and genetic structure in this organism.

Cross-tissue immune cell analysis reveals tissue-specific features in humans

Despite their crucial role in health and disease, our knowledge of immune cells within human tissues remains limited. We surveyed the immune compartment of 16 tissues from 12 adult donors by single-cell RNA sequencing and VDJ sequencing generating a dataset of ~360,000 cells. To systematically resolve immune cell heterogeneity across tissues, we developed CellTypist, a machine learning tool for rapid and precise cell type annotation. Using this approach, combined with detailed curation, we determined the tissue distribution of finely phenotyped immune cell types, revealing hitherto unappreciated tissue-specific features and clonal architecture of T and B cells. Our multitissue approach lays the foundation for identifying highly resolved immune cell types by leveraging a common reference dataset, tissue-integrated expression analysis, and antigen receptor sequencing.

Salivary acinar cells from aquaporin 5-deficient mice have decreased membrane water permeability and altered cell volume regulation

Aquaporins (AQPs) are channel proteins that regulate the movement of water through the plasma membrane of secretory and absorptive cells in response to osmotic gradients. In the salivary gland, AQP5 is the major aquaporin expressed on the apical membrane of acinar cells. Previous studies have shown that the volume of saliva secreted by AQP5-deficient mice is decreased, indicating a role for AQP5 in saliva secretion; however, the mechanism by which AQP5 regulates water transport in salivary acinar cells remains to be determined. Here we show that the decreased salivary flow rate and increased tonicity of the saliva secreted by Aqp5(-)/- mice in response to pilocarpine stimulation are not caused by changes in whole body fluid homeostasis, indicated by similar blood gas and electrolyte concentrations in urine and blood in wild-type and AQP5-deficient mice. In contrast, the water permeability in parotid and sublingual acinar cells isolated from Aqp5(-)/- mice is decreased significantly. Water permeability decreased by 65% in parotid and 77% in sublingual acinar cells from Aqp5(-)/- mice in response to hypertonicity-induced cell shrinkage and hypotonicity-induced cell swelling. These data show that AQP5 is the major pathway for regulating the water permeability in acinar cells, a critical property of the plasma membrane which determines the flow rate and ionic composition of secreted saliva.

A randomized trial to evaluate the risk of gastrointestinal disease due to consumption of drinking water meeting current microbiological standards

BACKGROUND

This project directly and empirically measured the level of gastrointestinal (GI) illness related to the consumption of tapwater prepared from sewage-contaminated surface waters and meeting current water quality criteria.

METHODS

A randomized intervention trial was carried out; 299 eligible households were supplied with domestic water filters (reverse-osmosis) that eliminate microbial and chemical contaminants from their water, and 307 households were left with their usual tapwater without a filter. The GI symptomatology was evaluated by means of a family health diary maintained prospectively by all study families over a 15-month period.

RESULTS

The estimated annual incidence of GI illness was 0.76 among tapwater drinkers compared with 0.50 among filtered water drinkers (p less than 0.01). These findings were consistently observed in all population subgroups.

CONCLUSION

It is estimated that 35% of the reported GI illnesses among the tapwater drinkers were water-related and preventable. Our results raise questions about the adequacy of current standards of drinking water quality to prevent water-borne endemic gastrointestinal illness.

Mouse down-regulated in adenoma (DRA) is an intestinal Cl(-)/HCO(3)(-) exchanger and is up-regulated in colon of mice lacking the NHE3 Na(+)/H(+) exchanger

Mutations in human DRA cause congenital chloride diarrhea, thereby raising the possibility that it functions as a Cl(-)/HCO(3)(-) exchanger. To test this hypothesis we cloned a cDNA encoding mouse DRA (mDRA) and analyzed its activity in cultured mammalian cells. When expressed in HEK 293 cells, mDRA conferred Na(+)-independent, electroneutral Cl(-)/CHO(3)(-) exchange activity. Removal of extracellular Cl(-) from medium containing HCO(3)(-) caused a rapid intracellular alkalinization, whereas the intracellular pH increase following Cl(-) removal from HCO(3)(-)-free medium was reduced greater than 7-fold. The intracellular alkalinization in Cl(-)-free, HCO(3)(-)-containing medium was unaffected by removal of extracellular Na(+) or by depolarization of the membrane by addition of 75 mM K(+) to the medium. Like human DRA mRNA, mDRA transcripts were expressed at high levels in cecum and colon and at lower levels in small intestine. The expression of mDRA mRNA was modestly up-regulated in the colon of mice lacking the NHE3 Na(+)/H(+) exchanger. These results show that DRA is a Cl(-)/HCO(3)(-) exchanger and suggest that it normally acts in concert with NHE3 to absorb NaCl and that in NHE3-deficient mice its activity is coupled with those of the sharply up-regulated colonic H(+),K(+)-ATPase and epithelial Na(+) channel to mediate electrolyte and fluid absorption.

The tolerability of dothiepin: a review of clinical studies between 1963 and 1990 in over 13,000 depressed patients

1. A total of 13,834 depressed patients were exposed to dothiepin most frequently at a dose of 150 mg/day and over 6 weeks, in 116 clinical studies between 1963 and 1990. 2. Overall, 2,066 (15%) patients were withdrawn prematurely from dothiepin for a variety of reasons, the most commonly specified reason being due to drug-related events in 500 (4%) patients. 3. In the remaining 11,768 patients, there were 9,312 reports of unwanted events most typically associated with the pharmacological effects of a tricyclic antidepressant although no serious sequelae were reported. 4. This review indicates that the incidence of serious adverse events associated with dothiepin at therapeutic doses is very low.

Mammary cancer in transgenic mice expressing insulin-like growth factor II (IGF-II)

The effect of insulin-like growth factor II (IGF-II) on tumour development in the mouse mammary gland was studied. To promote extra IGF-II expression in the mammary gland, sheep beta-lactoglobulin regulatory elements were attached to the coding regions of the mouse Igf-2 gene and injected into the pronuclei of mouse zygotes. Mammary tumours developed in each of the four independent lines of mice which expressed transgene IGF-II in the gland. Tumours from two of the lines grew after transplantation to both male and female hosts. Primary tumours contained stromal and epithelial regions, but the tumours were dominated by mammary adenocarcinoma after transplantation. The tumours expressed high levels of Igf-2 mRNA transcribed from the integrated transgenes.

Sulfated oligosaccharides promote hepatocyte growth factor association and govern its mitogenic activity

Hepatocyte growth factor (HGF) is a potent mitogen, motogen, and morphogen for various epithelial cell types. The pleiotropic effects of HGF are mediated by its binding to a specific high affinity receptor, c-Met. In addition, HGF binds to heparan sulfate proteoglycans on cell surfaces and within the extracellular matrix. Incubation of HGF with 0.1, 1.0, and 10 micrograms/ml of heparin, heparan sulfate, or dextran sulfate resulted in a concentration-dependent increase in mitogenic potency in a primary rat hepatocyte bioassay, whereas sodium sulfate or fucoidan did not. Although co-incubation of HGF with sulfated compounds that enhanced HGF-dependent mitogenesis did not alter the binding isotherm of HGF for the c-Met receptor in a solid phase assay, an increase in autophosphorylation of the c-Met receptor in intact A549 cells was observed upon their addition. A series of chemically sulfated malto-oligosaccharides varying in unit size and charge was tested in the bioassay in order to provide additional insights into the nature of the HGF-heparin interaction. While sulfated di-, tri-, tetra-, and pentasaccharides did not significantly potentiate HGF-dependent mitogenesis, larger oligosaccharides such as the sulfated hexa-, hepta-, or a sulfated oligosaccharide mixture containing decasaccharides resulted in an approximate 2-, 4-, and 7-fold enhancement, respectively. We observed a correlation between the sulfated oligosaccharide preparations that enhanced mitogenic potency and those that promoted HGF oligomerization in vitro, as measured by gel filtration and analytical ultracentrifugation. These findings indicate that heparin-like molecules can stabilize HGF oligomers, which may facilitate c-Met receptor dimerization and activation.

Characterization of proteins secreted by sheep oviduct epithelial cells and their function in embryonic development

The role in early development of proteins secreted by oviduct epithelial cells has been investigated. Secreted proteins devoid of serum contamination have been produced by the surgical removal and immediate incubation of oviduct cells in [35S]methionine-containing medium. After electrophoretic separation, secreted polypeptides could be divided into those that were secreted uniformly throughout the oestrous cycle and a second class that showed a cyclical pattern of secretion. The first class of proteins represented a small proportion of total output whilst the predominant second class was composed mainly of polypeptides of Mr 92 and 46 × 10(3), respectively. Both of these polypeptide species, referred to as sheep oviduct proteins 92 and 46 (SOP 92, SOP 46), are detected only during the first 4 to 5 days after oestrus when the embryos are located in the oviduct. Oviduct cells collected at oestrus and maintained thereafter in culture secrete the same pattern of proteins and follow the same time course as their counterparts in vivo. The interaction between the oviduct proteins and the developing embryo was studied firstly by determining whether any of the secreted proteins bound to the zona pellucida. The results of iodination studies showed that two polypeptides of Mr 92 and 46 × 10(3), respectively, were bound to the zona pellucida of eggs removed from the oviduct but were absent from eggs that had not had contact with the oviduct epithelium. That these newly acquired proteins represent SOP 92 and 46 is suggested by their electrophoretic mobility and their ability to bind to the zona of follicular eggs when added in vitro and by the fact that they both disappear from the zonae of embryos after exit from the oviduct. The collection of unlabelled secreted proteins enabled us to produce a monoclonal antibody, which was used in the second series of experiments on oviduct-embryo interactions. The results confirmed that SOP 92 binds to the zona pellucida and moreover showed that this protein crosses the zona and becomes associated with the individual blastomeres of the developing embryo. These findings provide evidence that the mammalian oviduct probably plays a direct role in supporting embryonic development through specific polypeptides produced by its epithelium.

Validation of short term recall of mobile phone use for the Interphone study

AIM

To validate short term recall of mobile phone use within Interphone, an international collaborative case control study of tumours of the brain, acoustic nerve, and salivary glands related to mobile telephone use.

METHODS

Mobile phone use of 672 volunteers in 11 countries was recorded by operators or through the use of software modified phones, and compared to use recalled six months later using the Interphone study questionnaire. Agreement between recalled and actual phone use was analysed using both categorical and continuous measures of number and duration of phone calls.

RESULTS

Correlations between recalled and actual phone use were moderate to high (ranging from 0.5 to 0.8 across countries) and of the same order for number and duration of calls. The kappa statistic demonstrated fair to moderate agreement for both number and duration of calls (weighted kappa ranging from 0.20 to 0.60 across countries). On average, subjects underestimated the number of calls per month (geometric mean ratio of recalled to actual = 0.92, 95% CI 0.85 to 0.99), whereas duration of calls was overestimated (geometric mean ratio = 1.42, 95% CI 1.29 to 1.56). The ratio of recalled to actual use increased with level of use, showing underestimation in light users and overestimation in heavy users. There was substantial heterogeneity in this ratio between countries. Inter-individual variation was also large, and increased with level of use.

CONCLUSIONS

Volunteer subjects recalled their recent phone use with moderate systematic error and substantial random error. This large random error can be expected to reduce the power of the Interphone study to detect an increase in risk of brain, acoustic nerve, and parotid gland tumours with increasing mobile phone use, if one exists.

The rat cim effect: TAP allele-dependent changes in a class I MHC anchor motif and evidence against C-terminal trimming of peptides in the ER

Functional polymorphism in the rat peptide transporter associated with antigen processing (TAP) changes the peptide pool available for binding and presentation by a class I MHC allele, RT1.Aa. The peptide binding motif for RT1.Aa, determined by stabilization with synthetic peptides, included a strong preference for arginine at the peptide C terminus. Analysis of natural peptides bound to RT1.Aa by both pool sequencing and anhydrotrypsin chromatography revealed that TAP polymorphism determined the presence or absence of arginine as the peptide C-terminal residue. This result highlights the in vivo impact of TAP-peptide selectivity, and provides evidence against a high rate of generation of new C termini by protease activity in the endoplasmic reticulum.

Risk of brain tumours in relation to estimated RF dose from mobile phones: results from five Interphone countries

Objectives

The objective of this study was to examine the associations of brain tumours with radio frequency (RF) fields from mobile phones.

Methods

Patients with brain tumour from the Australian, Canadian, French, Israeli and New Zealand components of the Interphone Study, whose tumours were localised by neuroradiologists, were analysed. Controls were matched on age, sex and region and allocated the ‘tumour location’ of their matched case. Analyses included 553 glioma and 676 meningioma cases and 1762 and 1911 controls, respectively. RF dose was estimated as total cumulative specific energy (TCSE; J/kg) absorbed at the tumour's estimated centre taking into account multiple RF exposure determinants.

Results

ORs with ever having been a regular mobile phone user were 0.93 (95% CI 0.73 to 1.18) for glioma and 0.80 (95% CI 0.66 to 0.96) for meningioma. ORs for glioma were below 1 in the first four quintiles of TCSE but above 1 in the highest quintile, 1.35 (95% CI 0.96 to 1.90). The OR increased with increasing TCSE 7+ years before diagnosis (p-trend 0.01; OR 1.91, 95% CI 1.05 to 3.47 in the highest quintile). A complementary analysis in which 44 glioma and 135 meningioma cases in the most exposed area of the brain were compared with gliomas and meningiomas located elsewhere in the brain showed increased ORs for tumours in the most exposed part of the brain in those with 10+ years of mobile phone use (OR 2.80, 95% CI 1.13 to 6.94 for glioma). Patterns for meningioma were similar, but ORs were lower, many below 1.0.

Conclusions

There were suggestions of an increased risk of glioma in long-term mobile phone users with high RF exposure and of similar, but apparently much smaller, increases in meningioma risk. The uncertainty of these results requires that they be replicated before a causal interpretation can be made.

Associations between several sites of cancer and nine organic dusts: results from an hypothesis-generating case-control study in Montreal, 1979-1983

A multi-cancer site, multi-factor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with over 2,000 subjects. All incident cases of 19 sites of cancer in males aged 35-70 and resident in Montreal were eligible. The interview was designed to obtain detailed lifetime job histories, and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included. For each site of cancer analyzed as a case series, controls were selected from among the other cancer sites in the study. This report concerns the associations between sites of cancer for which there were over 100 cases processed (stomach; colorectal, also analyzed by subsites; lung; prostate; bladder; kidney; non-Hodgkin's lymphoma) and nine organic dusts (wood; paper; grain; flour; fabrics; cotton; wool; synthetics; fur). All site-exposure combinations were investigated. The ones that provided the most interesting leads were lung-wood dust (odds ratio (OR) = 1.5), stomach-wood dust (OR = 1.5), colorectal-synthetic fiber (OR = 1.5), bladder-synthetic fiber (OR = 1.8), non-Hodgkin's lymphoma-cotton dust (OR = 1.9), colon-grain dust (OR = 2.6), prostate-grain dust (OR = 2.2), and prostate-paper dust (OR = 2.0). Only the associations with wood dust, synthetic fibers and cotton dust showed some evidence of "dose-response" with duration of exposure. Because it is such a common exposure and appears to increase lung and stomach cancer risks, wood dust may be responsible for a great deal of occupational cancer.

Self-assessed versus expert-assessed occupational exposures

While self-response to a checklist of substances may be a convenient and inexpensive method for obtaining information on occupational exposure, the validity of such information has not been evaluated. The objective of this report is to provide some evidence concerning validity of self-reported occupational exposures. In the context of a large case-control study, it was possible to compare self-reports with expert assessment, in which a team of industrial hygienists and chemists examined each job history individually and decided on likelihood of exposure. The subjects were 1,910 males who had participated in a population-based case-control study of cancer and occupational exposures conducted in Montreal, Canada, between 1979 and 1985. For each of 11 substances, the two methods of exposure assessment were compared by means of a kappa statistic and by computing the sensitivity and specificity of self-assessment against expert assessment. Kappa values ranged from 0.33 to 0.64. Compared with the expert assessment, specificities of the self-assessment were generally high (0.83-0.97, with a median of 0.90), but sensitivities were low (0.39-0.91, with a median of 0.61). The authors conclude that self-reports of occupational exposure are not sufficiently accurate to warrant their sole use in most community-based studies.

Associations between several sites of cancer and twelve petroleum-derived liquids. Results from a case-referent study in Montreal

A population-based case-referent study provided information on the associations between several types of cancer and 12 petroleum-derived liquids. All site-exposure combinations were investigated. The most interesting results concerned the following combinations: leaded gasoline-stomach cancer, aviation gasoline-kidney cancer (and the possible implications of this association for a similar effect of unleaded automotive gasoline), mineral spirits-squamous-cell cancer of the lung, diesel fuel-nonadenocarcinoma lung cancer, lubricating oils-squamous-cell lung cancer, cutting fluids-bladder cancer, other mineral oils-bladder cancer, mineral spirits-prostate cancer, diesel fuel-prostate cancer, and lubricating oils-prostate cancer.

Degree of confounding bias related to smoking, ethnic group, and socioeconomic status in estimates of the associations between occupation and cancer

In occupational cancer epidemiology, many studies are carried out without access to information on smoking and other potential confounding variables. It is unclear whether such deficiencies are likely to cause serious bias in estimates of cancer-occupation associations. An empiric investigation was carried out to determine the effect of inclusion or exclusion of three variables--smoking, ethnic group, and socioeconomic status--on estimates of odds ratios (OR) between 25 occupations and three types of cancer--lung, bladder, and stomach. Of the 75 associations studied, only one OR was distorted by more than 40% when comparing unadjusted with adjusted estimates; three were distorted by between 30% and 40%; four others by between 20% and 30%. Of the eight associations which were distorted by more than 20%, seven involved lung cancer and one involved bladder cancer; none involved stomach cancer. An additional analysis was carried out on the 25 lung cancer-occupation associations to determine whether the nature of the stratification on smoking (ie, whether crude or "precise" categories were used) gave different OR estimates. The differences in ORs induced by different parametrizations of the smoking variable were relatively small. Our results support the view that relative risks between lung cancer and occupation in excess of 1.4 are unlikely to be artifacts due to uncontrolled confounding. For bladder and stomach cancer, the corresponding cut point may be as low as 1.2. In studies of occupation and cancer, uncontrolled confounding due to smoking and social class may not be as serious a threat to the integrity of results as is sometimes feared.

Defective fluid secretion and NaCl absorption in the parotid glands of Na+/H+ exchanger-deficient mice

Multiple Na(+)/H(+) exchangers (NHEs) are expressed in salivary gland cells; however, their functions in the secretion of saliva by acinar cells and the subsequent modification of the ionic composition of this fluid by the ducts are unclear. Mice with targeted disruptions of the Nhe1, Nhe2, and Nhe3 genes were used to study the in vivo functions of these exchangers in parotid glands. Immunohistochemistry indicated that NHE1 was localized to the basolateral and NHE2 to apical membranes of both acinar and duct cells, whereas NHE3 was restricted to the apical region of duct cells. Na(+)/H(+) exchange was reduced more than 95% in acinar cells and greater than 80% in duct cells of NHE1-deficient mice (Nhe1(-/-)). Salivation in response to pilocarpine stimulation was reduced significantly in both Nhe1(-/-) and Nhe2(-/-) mice, particularly during prolonged stimulation, whereas the loss of NHE3 had no effect on secretion. Expression of Na(+)/K(+)/2Cl(-) cotransporter mRNA increased dramatically in Nhe1(-/-) parotid glands but not in those of Nhe2(-/-) or Nhe3(-/-) mice, suggesting that compensation occurs for the loss of NHE1. The sodium content, chloride activity and osmolality of saliva in Nhe2(-/-) or Nhe3(-/-) mice were comparable with those of wild-type mice. In contrast, Nhe1(-/-) mice displayed impaired NaCl absorption. These results suggest that in parotid duct cells apical NHE2 and NHE3 do not play a major role in Na(+) absorption. These results also demonstrate that basolateral NHE1 and apical NHE2 modulate saliva secretion in vivo, especially during sustained stimulation when secretion depends less on Na(+)/K(+)/2Cl(-) cotransporter activity.

Disproportionate growth in mice with Igf-2 transgenes

Injection transgenesis was used to study the long-term effects of excess insulin-like growth factor II on mouse growth and differentiation. By using a construct in which the coding region of the mouse insulin like growth factor II gene (Igf-2) was placed under the control of a keratin gene promoter, four transgenic lines were established, all of which displayed overgrowth of the skin as judged by wrinkling. In addition to high levels of expression in the skin, transgene transcripts were also present in the alimentary canal and uterus. At most of the sites of transgene expression the cell number (DNA content) was greatly increased, indicating a local action of the excess insulin-like growth factor II on cell multiplication. Adult total live weight was slightly increased and there was no macroscopic evidence of tumor formation. The characteristics of these transgenic mice indicate distinct local and systemic actions for insulin-like growth factor II.

Population differences in von Willebrand factor levels affect the diagnosis of von Willebrand disease in African-American women

Diagnosis of von Willebrand disease (vWD) is based on a panel of laboratory tests that measure the amount and function of von Willebrand factor (vWF). In population studies, vWF is higher in African Americans than Caucasians. Bleeding time, factor VIII activity (FVIII), vWF antigen (vWF:Ag), "vWF activity" ELISA (vWF:Act), ristocetin cofactor (vWF:RCof), and ristocetin-induced platelet aggregation (RIPA) were measured on 123 women with menorrhagia and 123 randomly selected control women; 70 cases and 76 controls were African American. Among controls, African Americans had significantly higher levels of vWF:Ag (mean 120 vs. 102 U/dl, P = 0.017). Among all subjects, African Americans had higher levels of vWF:Ag (mean 123 vs. 103, P = 0.001), vWF:Act (mean 101 vs. 89, P = 0.006), and FVIII (mean 118 vs. 104, P = 0.008). VWF:RCof did not differ between races (93 vs. 94 U/dl). RIPA was reduced in African Americans (P < 0.0001). In both races, women with type O blood differed significantly from those with other ABO types in vWF:Ag, vWF:Act, FVIII, and vWF:RCof. Based on criteria of two or more tests below race- and ABO-specific reference ranges, 6.5% of menorrhagia cases and 0.8% of controls were classified as having vWD, or its phenocopy. Among Caucasians, no controls and 7 cases (15.6%) were classified as affected, and in African Americans, 1 control (1.3%) and 1 case (1.4%) were so classified. Racial differences in vWF further complicate the issues surrounding diagnosis of vWD. The finding of increased vWF:Ag not accompanied by increased vWF:RCof has implications for understanding the structure-function relationships of vWF. Published 2001 Wiley-Liss, Inc.

Associations between several sites of cancer and ten types of exhaust and combustion products. Results from a case-referent study in Montreal

A population-based case-referent study provided information on the associations between several types of cancer and 10 types of exhaust and combustion products. All site-exposure combinations were investigated. An increased lung cancer risk, in particular squamous-cell cancers, due to exposure to gasoline and diesel exhausts was found. Among the associations that have not been subject to previous attention, the most promising leads for further investigation are the possible relations between gasoline and diesel exhaust and colorectal cancers, gasoline exhaust and kidney cancer, coal combustion products and pancreatic cancer (and possibly nonadenocarcinoma lung cancer), combustion products of heating oil and prostatic cancer, and natural-gas combustion products and bladder cancer.

Interference between non-A, non-B and hepatitis B virus infection in chimpanzees

Pre-existing chronic or concurrent acute non-A, non-B (NANB) virus infection has been found to interfere with hepatitis B virus (HBV) replication and to delay and moderate markedly the appearance of disease related to HBV infection in chimpanzees. The mechanism for this phenomenon remains unclear. These findings are of practical significance for vaccine safety testing and evaluation of methods for virus inactivation in chimpanzees. The possible occurrence of dual NANB and HBV infection requires that prolonged follow-up be carried out. Attempts to carry out inactivation studies on materials containing both types of virus may also provide misleading observations.

Discovering carcinogens in the occupational environment. Methods of data collection and analysis of a large case-referent monitoring system

A multi-cancer site, multi-factor, case-referent study was undertaken to generate hypotheses about possible occupational carcinogens. About 20 types of cancer were included. Incident cases among men aged 35-70 years and diagnosed in any of the major Montreal hospitals were eligible. Probing interviews were carried out for 3 726 eligible cases. The interview was designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included. For each site of cancer analyzed, referents were selected from among the other sites in the study. The analysis was carried out in stages. First a Mantel-Haenszel analysis was undertaken of all cancer-substance associations, stratifying on a limited number of covariates, and, then, for those associations which were noteworthy in the initial analysis, a logistic regression analysis was made taking into account all potential confounders. This report describes the fieldwork and analytical methods.

Patterns and predictors of asthma-related emergency department use in Harlem

STUDY OBJECTIVES

To assess the roles of poor access to care, psychological risk factors, and asthma severity in frequent emergency department (ED) use.

DESIGN

A cross-sectional survey.

SETTING

Harlem Hospital Center ED and outpatient chest clinic.

PARTICIPANTS

Three hundred seventy-five adult residents of Harlem, a predominantly African-American community in New York City.

MEASUREMENTS

Asthma severity was assessed by self-reported symptoms using National Asthma Education and Prevention Program guidelines, health-care utilization, and psychometric scales.

RESULTS

Respondents with more severe asthma were more likely to have a primary asthma care provider, and to have had more scheduled office visits for asthma in the year prior to the interview (mean number of visits for patients with severe asthma, 3.6 visits; moderate asthma, 2.4 visits; and mild asthma, 1.7 visits). Despite having a regular source of care, 69% of respondents identified the ED as their preferred source of care; 82% visited the ED more than once in the year prior to interview (median, four visits). Persons with moderate or severe asthma were 3.8 times more likely to be frequent ED users compared to those with mild asthma (odds ratio [OR], 3.8; 95% confidence interval [CI], 2.2 to 6.6). This was the strongest predictor of frequent ED use. Other predictors of ED use were number of comorbid disorders (OR, 1.5; 95% CI, 1.1 to 2.1) and self-reported global health in the year prior to the ED visit (OR, 1.8; 95% CI, 1.2 to 2.7). Psychological characteristics were not predictive of frequent ED use when controlling for disease severity.

CONCLUSIONS

Frequent ED users present with serious medical conditions. They do not substitute physician care with ED care; they augment it to address serious health needs.

Race-specific results of Papanicolaou testing and the rate of cervical neoplasia in the National Breast and Cervical Cancer Early Detection Program, 1991-1998 (United States)

OBJECTIVE

To describe differences in cervical screening and biopsy results by race or ethnicity from women in the National Breast and Cervical Cancer Early Detection Program (NBCCEDP).

METHODS

We examined the percentage of abnormalities detected by Papanicolaou (Pap) tests and the rate of biopsy-diagnosed high-grade precancerous or cancerous lesions by racial or ethnic group.

RESULTS

Almost half the 628,085 women screened were members of racial or ethnic minority groups. American Indian or Alaska Native women were more likely than others to report never having had a prior Pap test. American Indian or Alaska Native women had the highest proportion of abnormal Pap tests for first program screens (4.4%), followed by blacks (3.2%), whites (3.0%), Hispanics (2.7%), and Asians or Pacific Islanders (1.9%). Whites had the highest biopsy detection rate of high-grade lesions for first program screens (9.9 per 1000 Pap tests), followed by Hispanics (7.6), blacks (7.1), American Indians or Alaska Natives (6.7), and Asians or Pacific Islanders (5.4).

CONCLUSIONS

This program provides important data on the prevalence of cervical neoplasia among diverse populations. Our findings that black women with a high-grade Pap test were less likely to get a work-up are disconcerting and merit further study and ultimate correction.

E-learning vs lecture: which is the best approach to surgical teaching?

AIM

Most medical teaching is still delivered by traditional face-to-face interaction. E-learning has the potential benefit of instilling deeper learning of topics by virtue of repeated and convenient access to content presented in a range of media. We aimed to evaluate objectively the benefit of educating medical students on a common surgical topic (haemorrhoids), through a website and podcast package vs a traditional lecture.

METHOD

Baseline knowledge was established by a questionnaire given to two different groups of third-year medical students starting their first clinical attachment. Group A (n = 73) was given a lecture and group B (n = 75) was asked to use a website containing text and pictures augmented by a podcast. Students were reassessed using the same preintervention questionnaire, and satisfaction was acquired from details given in a feedback form.

RESULTS

There was no difference in knowledge between the two groups at baseline. Both groups demonstrated significant gains in knowledge after intervention (P < 0.0001). Group B (Web/podcast) showed a significantly greater increase in knowledge (P < 0.05) than group A (lecture). Preintervention subjective assessment of knowledge rated by the students showed no difference between the groups. Both groups of students were equally satisfied with the educational method.

CONCLUSION

E-learning supplemented with a podcast results in greater knowledge acquisition when compared with a traditional lecture, without a loss of satisfaction with teaching. Using augmented Web-based educational tools reduces demands on teaching time with no decrease in quality for selected parts of the curriculum.