Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Poisson Distribution”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed1985

Evidence of an association between bullous pemphigoid and psoriasis.

The medical records of 62 consecutive patients with bullous pemphigoid and 62 case-matched leg ulcer controls were examined to determine whether psoriasis and bullous pemphigoid are associated. Psoriasis occurred in seven of the pemphigoid patients (11%) but in none of the controls. The prevalence of psoriasis in the pemphigoid sample was significantly higher than expected (P less than 0.01, Poisson distribution). This difference, together with the clinical course, suggests that there may be an association between pemphigoid and psoriasis.

Aged↗
PubMed1977

Planning the suicide experiments.

Suicide experiments involve a great degree of uncertainty in the counting of cell colonies. This work studies from a statistical point of view the precision of the estimation as a function of the number of experimental units which are used. Assuming that the colony numbers in recipients follow a Poisson distribution, we give the necessary number of recipients (a) to determine with a given accuracy the percentage of DNA synthesizing cells (S cells), (b) to test whether or not a cell population is quiescent, and (c) to compare the percentages of S cells in two cell populations.

Animals↗
PubMed1988

The spleen colony technique. III. Comparison of the overlap effect and of errors in CFU-s determination and the [3H]-thymidine suicide data for several strains of mice.

A mathematical model of errors of the spleen colony technique is applied to data obtained from four mouse strains and F1 hybrids. The variance of the colony counts was close to the Poisson distribution in inbred mice and F1 hybrids. However, it should be checked regularly. The magnitude of the error in CFU-s determination and of the estimations of the S phase fraction was derived, and is presented relative to the mean colony counts for all mouse strains studied. The optimum spleen colony counts are generally higher than those which are commonly used. However, the utilization of the optimum spleen colony counts requires a correction for the effect of colony overlap.

Animals↗
PubMed1995

An increased frequency of IgE-producing B cell precursors contributes to the elevated levels of plasma IgE in atopic subjects.

BACKGROUND: The production of specific IgE, which underlies the allergic response, may be a normal correlate of the immune response to a certain class of antigen (allergens), or could represent a unique response driven by regulatory signals that are absent in non-allergic individuals. If atopic subjects do possess a regulatory environment favoring IgE production, they may display not only allergen-specific IgE, but also higher levels of total IgE and higher frequencies of IgE-producing B lymphocytes. OBJECTIVE: To address the contribution of antibody-producing cell number to the circulating IgE titre in atopic vs non-atopic subjects. METHODS: Frequency determination by limiting dilution of EBV transformants and Poisson distribution analysis. Titres of total and allergen-specific IgM, IgG, and IgE by specific ELISA. RESULTS: In contrast to findings reported by others, the atopic subjects had a significantly higher frequency of IgE-producing B cells than non-atopics (0.79% of total Ig-producing cells, as compared with 0.17% for the control group; P < 0.01), suggesting that one factor contributing to the high plasma IgE titres in atopic subjects is the high frequency of B lymphocytes with the potential to produce IgE. Although only the atopic subjects produced allergen-specific IgE, the frequency of specific IgE-producing B cells was undetectable in both groups. CONCLUSION: Atopic subjects have higher frequencies of IgE-producing B cell precursors than non-atopics. A correlation exists between IgE-producing B cell frequency and levels of circulating IgE.

Animals↗
PubMed2006

The association between malignant melanoma and noncutaneous malignancies.

BACKGROUND: Both increases and decreases in the incidence of subsequent malignancies in melanoma patients have been reported. We examined the database of the Indiana University Cancer Center to determine whether there is an association between malignant melanoma and noncutaneous malignancies. OBJECTIVE: We searched for evidence of noncutaneous malignancies in a cohort of melanoma patients. METHODS: Patients with microscopically confirmed malignant melanoma diagnosed between January 1987 and March 2001 were analyzed. This cohort was investigated for noncutaneous malignancies occurring either before or after the diagnosis of melanoma. The standardized incidence ratios (SIR) were calculated as the ratio of the observed to the expected number of patients with second malignancies, and 95% confidence intervals (95% CI) around the SIR were estimated from the cumulative Poisson distribution. RESULTS: A total of 955 patients with melanoma (498 males and 457 females) were documented over the 14-year period. Sixty-nine noncutaneous malignancies were identified in 59 (6.2%) melanoma patients (39 males and 20 females). There was a higher risk of non-Hodgkin's lymphoma (SIR = 1.91; 95% CI, 0.88-3.62) in men and renal cell carcinoma (SIR = 2.41, 95% CI, 0.97-4.97) in men. In female patients, however, there was no higher risk of noncutaneous malignancies. CONCLUSIONS: This study did not show a higher risk of prostate cancer, gastrointestinal cancer, leukemia, endometrial cancer, or cancer of the nerve and neuroendocrine systems in melanoma patients. No female patients incurred a higher risk of noncutaneous cancers. The increased risk of non-Hodgkin's lymphoma and renal cell carcinoma in men might be attributed to a mutual carcinogenic exposure, an aberration of cell-mediated immunity, a shared genetic susceptibility, increased medical surveillance among cancer patients, a post-therapy effect after cancer management, or factors not as yet clear. Close monitoring of melanoma patients for signs of second malignancy is warranted.

Carcinoma, Renal Cell↗
PubMed2006

No evidence of West Nile virus infection in Dutch blood donors.

BACKGROUND AND OBJECTIVES: West Nile virus (WNV) can be transmitted by transfusion through infected blood components. This study aimed to determine the prevalence of WNV infection among Dutch blood donors to assess whether WNV is a possible threat for the Dutch blood supply. MATERIALS AND METHODS: Plasma samples from 61 992 blood donations were pooled in 7,749 test pools of eight donations using a Tecan robot. These samples were collected between April and October 2004. The pools were tested for the presence of WNV RNA by using the Procleix WNV assay. RESULTS: No WNV RNA-positive pools were detected. Based on Poisson distribution statistics, extrapolation of our data to all the Dutch donations in 2004 revealed that between 0 and 55 cases of WNV infection could be expected. CONCLUSIONS: No evidence of the presence of WNV RNA in Dutch blood donor samples from 2004 was found. However, surveillance of this emerging infection is of importance to safeguard the blood supply in the future because the transmission cycle of WNV is complex and hard to predict.

Blood Banks↗
PubMed2006

Stress as a cause of chronic recurrent vulvovaginal candidosis and the effectiveness of the conventional antimycotic therapy.

Chronic Candida vulvovaginitis cannot, at present, be treated effectively with local or oral antimycotic medication. Göttlicher & Meyer [Vulvovaginalmykose. Klinische Ergebnisse einer epidemiologischen Langzeitstudie, Thieme, Stuttgart (1998); Mycoses41 (1998) 49] formulated a hypothesis to explain this fact. They say that stress is the main cause of vulvovaginal mycosis, and that frequently cited predisposing somatic risk factors are not causing the illness. Two research projects were carried out to test this hypothesis. The first project was conceived to provide direct evidence for two empirical statements derived from the Göttlicher-Meyer hypothesis: (i) stress as a predictor of vulvovaginitis is least valid as the commonly assumed somatic factors and (ii) combinations of factors that reliably discriminate index women from symptom-free women point to aspects of psychosocial development, particularly stress, and not to somatic factors. Between March and November 1999, 309 successive patients were randomly chosen from those successively treated in one in-patient and two out-patient settings. Of those chosen, 117 had had at least one episode of vaginal candidosis within the 2 years prior to enlistment in the study. The remaining 192 patients had experienced no such illness. For the 117 index patients both of the above empirical statements were confirmed by statistical analyses. The second project was designed to test predictions concerning the ineffectiveness of traditional antimycotic treatment derived from the Göttlicher-Meyer hypothesis. Three different empirical statements were derived from the hypothesis--each based on the assumption of a Poisson distribution of relapses that remains uninfluenced by treatment attempts. Each of the statements was tested and confirmed in independent samples--the first in the sample used in project one, the second in a sample of 206 women insured by public Healths Management Organizations (HMOs) and the third in a sample of 179 women insured by private HMOs. Each patient had evidenced Candida albicans vulvovaginitis at least once in the time interval between 1996 and 2000. Statistical analyses confirmed each of the empirical statements, thereby substantiating the Göttlicher-Meyer hypothesis. The authors conclude that (i) psychosocial factors, particularly stress, are the primary causes of Candida albicans vulvovaginitis. Accompanying somatic factors are of little statistical significance in explaining occurrence and relapse. (ii) Traditional antimycotic treatment influences only the symptoms of the illness, not its causes, and has no effect on the probability of a relapse. Increased treatment effectiveness can be achieved only at the cost of a complete re-orientation concerning the causes of vaginal mycosis. Interventions designed to strengthen the patients' immune response are among the most promising.

Antifungal Agents↗
PubMed1994

Trends in the incidence of end-stage renal failure due to hypertension and vascular disease in Australia, 1972-1991.

BACKGROUND: Despite the known protective effects upon renal function of lowering blood pressure in primary chronic renal disease, diabetes and malignant hypertension, the number of patients entering dialysis and transplantation programmes with renal failure due to hypertension or vascular disease remains high. AIMS: To analyse the trends in incidence of arteriopathic end-stage renal failure. METHODS: Calculation of mean annual age- and sex-specific rates (by decade) and truncated age-standardised rates for entry into Australian end-stage renal failure programmes in the period 1972-1991. Statistical analysis by chi-squared test, assuming a Poisson distribution of cases. RESULTS: End-stage renal failure attributed primarily to hypertension or vascular disease fell to less than half its former level over the period of observation in persons aged 15-54 years. This change has occurred only in the diagnostic category 'malignant hypertension'. Trends in persons aged 55 years and over are more difficult to analyse because of changing criteria for entry into renal failure programmes, but there has been no indication of any fall in incidence. CONCLUSIONS: The aetiology and pathology of arteriopathic renal failure is diverse, with different patterns in young and old adults. The formerly common pathology in young adults is largely preventable by modern antihypertensive therapy, while arteriopathic renal disease in older persons is not.

Adolescent↗
PubMed1979

An alternative model of recombination and interference.

A model of four-strand crossing-over is presented in which all non-randomness is attributed to the non-Poisson distribution of the number of exchanges. Nth order recombination fractions and the coefficient of coincidence are calculated in terms of the model. It is shown that coincidence may be greater or less than unity depending on the prior distribution of exchanges. An obligate exchange is a sufficient condition for coincidence to be less than unity if there is a maximum of four exchanges, but not necessarily if five or more are possible. It is also shown that marginal coincidence is an insufficient concept to explain the behaviour of coincidence over its entire two-dimensional domain.

Chromosome Mapping↗
PubMed1992

Prevalence of hepatitis B and C viruses and human immunodeficiency virus infections in women of reproductive age.

OBJECTIVE: To determine the prevalence of hepatitis B and C viruses, and human immunodeficiency virus infections in women of reproductive age attending a health care system. DESIGN: Prospective cross-sectional study. SETTING: Public Obstetric Clinic and Service for Pre- and Perinatal Prevention of Infectious Diseases, Rome, Latium Region, Italy. SUBJECTS: 1142 women attending our centres consecutively for delivery, miscarriage, voluntary interruption of pregnancy or screening for pre- and perinatal prevention of infectious diseases. INTERVENTIONS: Serum samples, collected after informed consent over a period of 2 months, were tested for hepatitis B virus markers (anti-HBc and HBsAg) by enzyme linked immunosorbent assay (ELISA), for antibodies against hepatitis C virus (by ELISA and, if positive, by RIBA) and for human immunodeficiency virus antibodies (by ELISA and, if positive by Western blot). RESULTS: The seroprevalence of hepatitis B virus was 14.4% (95% CI Poisson distribution 12.2-16.5) for anti-HBc and 1.6% (95% CI, 0.9-2.5) for HBsAg. Antibodies against hepatitis C virus were detected by ELISA in 2.4% (CI 1.6-3.5) and by first generation RIBA in 0.9% (CI 0.4-1.6). Human immunodeficiency virus seroprevalence was 1.0% (CI 0.5-1.7). No significant differences were observed by age or by reason for attending. CONCLUSIONS: Women attending our centres have a higher prevalence of hepatitis B virus, hepatitis C virus and human immunodeficiency virus infection than those observed in our country in larger national surveys of newborn babies, in reproductive-aged women or in other selected low-risk groups such as blood donors. This could be due to the attendance of women at increased risk such as drug addicts. The information has the additional value of emphasizing the need for adherence by health care personnel, to the recommendations issued for the prevention of occupational infections.

Adult↗
PubMed1985

What is the actual incidence of peritonitis in maintenance peritoneal dialysis? A prospective study.

Generally, the incidence of peritonitis in maintenance peritoneal dialysis programs is calculated as a percentage of the total number of treatments or as the number of episodes per patient-months. Both statistical methods give the wrong impression that peritonitis is seldom observed. However, peritonitis is still the major and unsolved challenge to successful long-term peritoneal dialysis. The lack of a standard and homogeneous definition of peritonitis is another critical point that prevents a rational interpretation of the published experiences. In the present study, dialysate cell counts of greater than 1,100 cells/mm3 were assumed to be the first sign of peritoneal infection. As long as more signs and symptoms are required for recognizing peritonitis (fever, abdominal pains, positive cultures), the statistical probability of making such a diagnosis shows the characteristics of a Poisson distribution. It is concluded that in long-term peritoneal dialysis, the currently used statistical methodology for evaluation of the incidence of peritonitis, including the clinical definition of this complication, is misleading. Dialysate cell counts appear to be the more sensitive sign for early diagnosis of peritonitis.

Adult↗
PubMed2005

Collaborative study to evaluate a working reagent for West Nile virus RNA detection by nucleic acid testing.

BACKGROUND: A nucleic acid test (NAT) assay reference reagent for West Nile virus (WNV) RNA, consisting of heat-inactivated WNV grown in tissue culture and diluted in pooled, negative human plasma, was evaluated and quantitated in a collaborative study in which 14 laboratories participated. STUDY DESIGN AND METHODS: Participants were requested to assay serial half-log and log dilutions of the reagent to determine the RNA endpoint. A single endpoint for each such dilution series was calculated with the maximum likelihood method, which assumes that the probability of a positive result at a given dilution follows a Poisson distribution. The calculated endpoint was used to give an estimated "NAT-detectable units per mL" (not necessarily equivalent to genome equivalents/mL or copies/mL). The assays used by participants included qualitative and quantitative NAT assays and both the commercial WNV assays (Chiron and Roche). RESULTS: The estimated number of detectable units per mL for the 14 laboratories varied from log 2.0 to 3.0 with the exception of two outliers. The overall mean titer for all the assays was log 2.52 detectable units per mL (330 detectable units/mL). Multiple testing of individual vials by two laboratories indicated that there was no evidence of vial-to-vial variation in WNV content of the reference reagent. CONCLUSION: A reference reagent for WNV NAT assays has been established. The mean titer of the reagent, with the results from 14 laboratories, was 330 detectable units per mL.

Humans↗
PubMed1994

Estimated risk of occupational fatalities associated with hazardous waste site remediation.

This study presents a method to assess short term traumatic fatality risks for workers involved in hazardous waste site remediation to provide a quantitative, rather than qualitative, basis for evaluating occupational exposures in remediation feasibility studies. Occupational employment and fatality data for the years 1979-1981 and 1983 were compiled from Bureau of Labor Statistics data for 11 states. These data were analyzed for 17 occupations associated with three common remediation alternatives: excavation and landfill, capping, and capping plus slurry wall. The two occupations with the highest death rates, truck driver and laborer, contributed most to total exposure hours in each alternative. Weighted average death rates were produced for each alternative and multiplied by respective total person-years of exposure. The resultant expected number of fatalities was converted, using the Poisson distribution, to the risk of experiencing at least one fatality, as follows: 0.149 for excavation and landfill, 0.012 for capping, and 0.014 for capping plus slurry wall. These risks were discussed in light of the need to obtain more reliable and comprehensive data than are currently available on the occupational safety and health risks associated with hazardous waste site remediation and the need for a more scientific, quantitative approach to remediation decisions involving risks to workers.

Accidents, Occupational↗
PubMed1999

Attempted suicide and major public holidays in Europe: findings from the WHO/EURO Multicentre Study on Parasuicide.

OBJECTIVE: The aim of the study was to examine the relationship between suicide attempts and major public holidays in Europe. METHOD: The analysis was based on data on 24 388 suicide attempts by persons aged 15 years or older in the period 1989-1996. Data from 13 centres (representing 11 countries) participating in the WHO/EURO Multicentre Study on Parasuicide were analysed. The analysis of the fluctuation of suicide attempts around public holidays was based on the daily number of suicide attempts for each centre. For each day in the period under examination a mean number of suicide attempts (mu) was calculated. The analysis was based on the assumption that the data followed a Poisson distribution. The observed number of daily suicide attempts was compared with the expected number of attempts. A multiplicative model for the expected number in each centre was developed. RESULTS: Before Christmas there were fewer suicide attempts than expected, and after Christmas there were approximately 40% more attempts than expected. In addition, more attempts than expected were registered on New Year's Day. In countries where people have the day off work on Whit Monday there were significantly fewer attempts during the 3 days before, but where Whit Monday is a normal working day significantly fewer attempts occurred on the Monday to Wednesday after Whit Sunday. CONCLUSION: There appears to be a transposition of a significant number of suicide attempts from before (and during) a major public holiday until after it. The division of holidays into non-working and working days showed that a 'holiday effect' could only be found around major public holidays, particularly Christmas, Easter and Whitsun. These findings support the theory of the 'broken-promise effect' for major public holidays.

Adolescent↗
PubMed1984

Differences in phagocytic/adherence properties between normal neutrophils.

Neutrophils, serum opsonins and staphylococci were incubated at 37 degrees C with continuous end-over-end rotation. The observed frequency of neutrophils with 0, 1, 2... staphylococci deviated systematically from that expected for a Poisson distribution. This suggests marked differences in phagocytosis/adherence between the neutrophils, indicating different neutrophil populations.

Cell Adhesion↗
PubMed1993

Sister chromatid exchange in the goat (Capra hircus).

Lymphocyte cells from 30 Maltese and Syrian derivative goats (13 males and 17 females) reared in southern Italy underwent sister chromatid exchange (SCE) test. For the 902 cells we studied, the SCE-mean values were 6.6 +/- 3.0 per cell for both breeds. The SCE-frequency did not follow a Poisson distribution. The simultaneous visualization of SCEs and G-bands in the lightly stained chromatid allowed the study of SCE-distribution in chromosomes 1 and X. The number of SCEs in chromosome 1 was significantly higher (P > 0.001) than expected from relative chromosome length. No statistical differences between the numbers of SCEs in the active (early-replicating) and inactive (late-replicating) X-chromosomes of female cells were found.

Animals↗
PubMed2004

Statistical and image analysis of sister chromatid exchange in maize.

The present study reports the use of the fluorescence plus Giemsa (FPG) technique, image analysis and statistical methods to assess the sister chromatid exchanges (SCEs) frequency in maize. Roots derived from germinated maize seeds were treated with BrdU solution and fixed. The slides were prepared by enzymatic cellular dissociation, air-drying technique, stained with Hoechst 33258 fluorochrome, and incubated in salt solution. The chromosomes were irradiated with ultraviolet light and stained with Giemsa solution. The FPG technique associated with digital analysis system was used to measure the length of 597 BrdU-incorporated maize chromosomes and to identify 0.5243 SCE per chromosome. A range from 0 to 4 SCE events were classified and the chi-square test (chi2=1.586, P=0.662) showed a good fit to the hypothesis that the SCEs are independent and random events that follow Poisson distribution. The SCE frequencies in long and short chromosome arms corresponded to a mean value of 0.876 SCE microm(-1). Considering that the maize line used in this study contains 5.78 picogram (pg) DNA (2C value) in interphasic G0/G1 nuclei or 11.56 pg DNA (4C value) in metaphase, and that the DNA mean value corresponds to 0.578 pg/metaphasic chromosome, the analysis suggests an occurrence of approximately 0.9 SCE/pg DNA.

Azure Stains↗
PubMed1981

Loss of Treponema pallidum during incubation in Nelson's survival medium with or without serum added.

Treponema pallidum organisms suspended in equal parts of Nelson's survival medium alone and with addition of various sera were counted in 5 microliters samples before and after 18 hours' anaerobic incubation at 35 degrees C. Samples in which the treponemes were not Poisson-distributed were excluded from the study. A loss of greater than 30% occurred in 230 out of 391 samples. The disappearance of treponemes did not seem to be caused by treponemal agglutination during incubation. There was no adherence of treponemes to the formed elements remaining in the suspension. The loss was not dependent on the concentration of syphilitic serum, nor was it influenced by the presence of immobilizing antibody in the serum. Lack of rigorous anaerobiosis during the manipulations did not influence the treponemal loss. The loss was independent of the density of the treponemal suspensions which did not contain unheated guinea-pig serum (GPS). The relative frequency of the loss exceeding 30% was highest in suspensions containing unheated GPS. However, the extent of loss in individual samples was haphazardly distributed among suspensions of all the compositions examined. The loss of treponemes seems to depend on at least two factors: a) a factor which is eluted together with the treponemes from the syphilitic orchitis and b) the presence of active guinea-pig complement. It is conjectured that the complement is non-immunologically activated and acts through the alternative pathway.

Agglutination↗