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PubMed1984

[Morphometric observations on the number of neurons in spinal ganglia].

Nerve cell number has been determined in the thoracic spinal ganglia XVII to XXII of chick embryos of 14-18 days of incubation. It is shown that these ganglia constitute a statistically homogeneous population in respect of the number of their constituent nerve cells. The statistical frequency distribution of the thoracic spinal ganglia according to the number of their neurons is unimodal, but markedly asymmetrical with a distinct positive skewness; the distribution differs significantly (P less than 0.05) from a normal (Gaussian) distribution.

Animals↗
PubMed1996

Restriction fragment length polymorphism of HLA-DR and HLA-DQ allotypes in four endogamous groups of western India.

HLA-DR and HLA-DQ allele frequencies in four populations (Brahmin, Maratha, Gujarati Hindu Patel, and Parsi) of Bombay, western India, were analyzed using TaqI RFLPs detected by the cDNA probes DRB, DQB, and DQA. Although the overall differences in the HLA-DR and HLA-DQ genotype frequencies among the populations were not statistically significant, several population-specific haplotypes were significant. Multivariate analyses using data on 2 loci (HLA-DR and HLA-DQ) produced a meaningful pattern of genetic affinity and differentiation that parallels the analysis made when frequency data on 23 loci (21 blood group and protein loci and 2 class II antigen loci) are used. The RST for class II loci was 0.006; the genetic differentiation increased to 0.01 when data on 23 polymorphic loci were analyzed. The genetic affinity analysis shows the isolated nature of the Parsi and close genetic affinity between the two local populations of Bombay. Although the RFLP technique has several limitations compared with newly defined PCR-based methods, our analysis shows that the RFLP technique is still a useful adjunct method for studying HLA polymorphisms for which only limited data from the populations of the Indian subcontinent are available.

Consanguinity↗
PubMed2003

Linkage disequilibrium between minisatellite loci supports clonal evolution of Mycobacterium tuberculosis in a high tuberculosis incidence area.

Deciphering the structure of pathogen populations is instrumental for the understanding of the epidemiology and history of infectious diseases and for their control. Although Mycobacterium tuberculosis is the most widespread infectious agent in humans, its actual population structure has remained hypothetical until now because: (i) its structural genes are poorly polymorphic; (ii) adequate samples and appropriate statistics for population genetic analysis have not been considered. To investigate this structure, we analysed the statistical associations (linkage disequilibrium) between 12 independent M. tuberculosis minisatellite-like loci by high-throughput genotyping within a model population of 209 isolates representative of the genetic diversity in an area with a very high incidence of tuberculosis. These loci contain variable number tandem repeats (VNTRs) of genetic elements named mycobacterial interspersed repetitive units (MIRUs). Highly significant linkage disequilibrium was detected among the MIRU-VNTR loci in this model. This linkage disequilibrium was also evident when the MIRU-VNTR types were compared with the IS6110 restriction fragment length polymorphism types. These results support a predominant clonal evolution of M. tuberculosis.

Bacterial Typing Techniques↗
PubMed1993

Measurement of HPRT mutant frequencies in T-lymphocytes from healthy human populations.

Somatic cell mutant frequencies at the hprt locus of the X-chromosome were measured with the T-lymphocyte cloning technique in healthy human populations. A statistical analysis was performed of assays from 232 individuals (77 males and 155 females) ranging in age from 19 to 80 years. Data from 4 donor groups were compiled: (a) 132 participants in a study of identical and fraternal twins; (b) 17 health care workers studied as part of an assessment of the risks of handling chemotherapeutic drugs; (c) 62 women with benign breast masses; and (d) 21 normal laboratory and office personnel. The relationship between age and mutant frequency (MF) was expressed by the equation: ln MF = 1.46 + 0.018 age (P < 0.001). Thus, MF increased by about 2% per year. Increases in cloning efficiency (CE) reduced the MF, as shown in the equation: ln MF = 2.91 - 1.32 CE (P < 0.001). CE was significantly related to age (CE = 0.47 - 0.002 age, P = 0.038), and the interdependent relationship between MF, age and CE expressed by the equation: ln MF = 1.99 - 1.13 CE + 0.016 age was significant at the P < 0.001 level. There was no statistically significant effect of donor gender or smoking history on MF in our population, but CE was significantly lower in males (P < 0.001). These findings confirm the importance of age and CE as factors which influence the thioguanine-resistant MF in circulating T-lymphocytes from normal adults.

Adult↗
PubMed2005

4-Aminobiphenyl-hemoglobin adducts and risk of smoking-related disease in never smokers and former smokers in the European Prospective Investigation into Cancer and Nutrition prospective study.

The aim of this study was to evaluate whether biomarkers of environmental tobacco smoke exposure [i.e., 4-aminobiphenyl-hemoglobin (4-ABP-Hb) adducts] were predictive of the risk of tobacco-related cancers and diseases. We did a case-control study nested within the European Prospective Investigation into Cancer and Nutrition, involving 190 controls and 149 cases (incident cancer of the lung, bladder, pharynx, larynx, oral cavity, leukemias, and chronic obstructive pulmonary disease or emphysema deaths). All individuals were never smokers or ex smokers for >10 years. 4-ABP-Hb adducts were analyzed in peripheral blood collected before the onset of the disease (median, 7 years). Overall, 4-ABP-Hb adducts were higher, although not statistically significantly so, in cases (as a whole) than controls. In the control population, high fruit and vegetable consumption significantly lowered the frequency of detectable adducts (Fisher's exact test, P = 0.025). Restricting the analysis to women, 4-ABP-Hb adducts were higher in cases than controls (Mann-Whitney P = 0.036) and the odds ratio (OR) for the presence/absence of adducts was 2.42 [95% confidence interval (95% CI), 1.18-4.98]. Moreover, the association of adducts with the individual cancer types was stronger in women than in the whole study population, although statistically significant only for leukemias (OR, 2.77; 95% CI, 1.06-7.20). The results provide some evidence that women may be more susceptible to environmental tobacco smoke, as suggested by their higher adduct levels. The most important finding of this prospective study is that, at least in women, 4-ABP-Hb adducts may help identify subjects at high risk of cancers related to environmental tobacco smoke exposure.

Biomarkers↗
PubMed1998

How many physicians does Canada need to care for our aging population?

BACKGROUND: There is concern that the aging of Canada's population will strain our health care system. The authors address this concern by examining changes in the physician supply between 1986 and 1994 and by assessing the availability of physicians in 1994 relative to population growth and aging, and relative to supply levels in the benchmark province of Alberta. METHODS: Physician numbers were obtained from the Canadian Institute for Health Information. The amount of services provided by each specialty to each patient age group was analysed using Manitoba physician claims data. Population growth statistics were obtained from Statistics Canada. Age- and specialty-specific utilization data and age-specific population growth patterns were used to estimate the number and type of physicians that would have been required in each province to keep up with population growth between 1986 and 1994, in comparison with actual changes in the physician numbers. Physician supply in Alberta was used as a benchmark against which other provinces were measured. RESULTS: Overall, Canada's physician supply between 1986 and 1994 kept pace with population growth and aging. Some specialties grew much faster than population changes warranted, whereas others grew more slowly. By province, the supply of general practitioners (GPs) grew much faster than the population served in New Brunswick (16.6%), Alberta (6.5%) and Quebec (5.3%); the GP supply lagged behind in Prince Edward Island (-5.4%). Specialist supply outpaced population growth substantially in Nova Scotia (10.4%), Newfoundland (8.5%), New Brunswick (7.3%) and Saskatchewan (6.8%); it lagged behind in British Columbia (-9.2%). Using Alberta as the benchmark resulted in a different assessment: Newfoundland (15.5%) and BC (11.7%) had large surpluses of GPs by 1994, whereas PEI (-21.1%), New Brunswick (-14.8%) and Manitoba (-11.1%) had substantial deficits; Quebec (37.3%), Ontario (24.0%), Nova Scotia (11.6%), Manitoba (8.2%) and BC (7.6%) had large surpluses of specialists by 1994, whereas PEI (-28.6%), New Brunswick (-25.9%) and Newfoundland (-23.8%) had large deficits. INTERPRETATION: The aging of Canada's population poses no threat of shortage to the Canadian physician supply in general, nor to most specialist groups. The marked deviations in provincial physician supply from that of the benchmark province challenge us to understand the costs and benefits of variations in physician resources across Canada and to achieve a more equitable needs-based availability of physicians within provinces and across the country.

Adolescent↗
PubMed1994

Future manpower needs in caring for an older cancer-patient population.

The Minnesota Cancer Surveillance System provides data for almost all cancers newly diagnosed in residents of Minnesota. A statistical method, Population Cancer Risk (PCR), estimates the total number of cancers that will occur in the lifetimes of 1,000 people, based on the Minnesota cancer incidence and life expectancy rates from 1988-1990. The overall PCR is 459 cancers per 1,000 lifetimes of persons born today. By year 2020 the Minnesota population will have increased 12% since 1990, but the total cancer incidence will have increased 60%. As a result, there will be an increased demand for medical oncologists, radiotherapists, and surgical subspecialists. Primary care physicians will play an increasing role in cancer prevention, early detection, therapies, and long-term follow-up. Physician's assistants and skilled nurses will add further to patient cancer management. Cancer patients will be older, on average. The future will include changes in the methods of care of the older cancer patients and in economic, social, and bioethical issues involving older persons.

Adult↗
PubMed2003

Mitochondrial diversity evaluated by the single strand conformation polymorphism method in African and North American house flies (Musca domestica L.).

Single strand conformation polymorphisms (SSCPs) provide a convenient and inexpensive method of surveying mitochondrial genetic variation in large samples. We investigated how much variation should be incorporated into such surveys by scoring SSCP variation at eight mitochondrial loci in each of four sub-Saharan African and four North American house fly (Diptera: Muscidae.) populations. Hierarchical analysis of diversity was performed on haplotype frequencies at each locus and on haplotype frequencies formed by combining haplotypes from two, three, four, five and eight loci. Composite haplotypes at two loci were as informative about population structure as those composed of a greater number of loci. Increasing the number of loci increased diversity estimates within, but not between, populations. Mean composite haplotype diversities (16S2 and COII) were 0.49 +/- 0.09 among the African populations and 0.32 +/- 0.08 among the North American populations. Only two of 16 haplotypes were shared between continents. Nei's genetic differentiation statistic between populations in continents GPC was 0.30 +/- 0.06 and mean genetic differentiation between continents GCT was 0.39 +/- 0.06. We conclude that there has been little detectable gene flow between North America and sub-Saharan Africa.

Africa South of the Sahara↗
PubMed2002

Variable response to exogenous Lactobacillus acidophilus NCFM consumed in different delivery vehicles.

AIMS: To study the effects of the delivery vehicle for Lactobacillus acidophilus on the human faecal microbiota. Our hypotheses were that (i) the delivery vehicle would influence faecal lactobacilli numbers and (ii) consumption of Lact. acidophilus would influence the populations of Bifidobacterium and hydrogen sulphide-producing bacteria. METHODS AND RESULTS: Ten subjects each received Lact. acidophilus with skim milk or water. Lactobacillus, Bifidobacterium and hydrogen sulphide-producing bacterial populations were analysed before, during and after each treatment. Regardless of the vehicle, faecal lactobacilli populations changed during treatment. Bifidobacteria and the hydrogen sulphide-producing bacteria underwent no statistically significant population changes. Intra- and intersubject variability was observed. CONCLUSIONS: The vehicle in which Lact. acidophilus was delivered did not influence faecal lactobacilli numbers. Consumption of Lact. acidophilus did not influence the populations of Bifidobacterium and hydrogen sulphide-producing bacteria. The lactobacilli populations of subjects were variable. The fed lactobacilli did not appear to colonize the gastrointestinal tract. SIGNIFICANCE AND IMPACT OF THE STUDY: We provide evidence that (i) there was no collective advantage to using skim milk as a delivery vehicle vs water; (ii) exogenous Lact. acidophilus did not affect endogenous bifidobacteria or hydrogen sulphide-producing bacteria; (iii) data should be carefully examined before pooling for analysis and (iv) continuous feeding was required to maintain an elevated lactobacilli population.

Adult↗