Image processing techniques for identifying Mycobacterium tuberculosis in Ziehl-Neelsen stains.

Worldwide, laboratory technicians tediously read sputum smears for tuberculosis (TB) diagnosis. We demonstrate proof of principle of an innovative computational algorithm that successfully recognizes Ziehl-Neelsen (ZN) stained acid-fast bacilli (AFB) in digital images. Automated, multi-stage, color-based Bayesian segmentation identified possible 'TB objects', removed artifacts by shape comparison and color-labeled objects as 'definite', 'possible' or 'non-TB', bypassing photomicrographic calibration. Superimposed AFB clusters, extreme stain variation and low depth of field were challenges. Our novel method facilitates electronic diagnosis of TB, permitting wider application in developing countries where fluorescent microscopy is currently inaccessible and unaffordable. We plan refinement and validation in the future.

Recurrent tuberculosis and its risk factors: adequately treated patients are still at high risk.

Recurrent tuberculosis (TB) poses significant threats, including drug resistance, to TB control programs. However, recurrence and its causes, particularly in the era of epidemic human immunodeficiency virus (HIV), have not been well described. We systematically searched published material for studies reporting on recurrent TB following completion of standard treatment regimens to provide data on the issue. A total of 32 studies were reviewed. Among controlled trials, the overall recurrence rates (per 100,000 person-years) were respectively 3,010 (95%CI 2,230-3,970) and 2,290 (95%CI 1,730-2,940) at 6 and 12 months after treatment completion. Recurrence rates were higher among observational studies compared to controlled trials and in countries with high versus low background TB incidence. TB recurrence (%) was higher among HIV-infected (6.7, 95%CI 5.9-7.6) than non-HIV-infected individuals (3.3, 95%CI 2.8-3.9). Factors independently associated with recurrence in the literature included residual cavitation, greater area of involved lung tissue, positive sputum culture at 2 months of treatment and HIV infection. Among those with HIV infection, recurrent TB was associated with a low initial CD(4) count and receiving less than 37 weeks of anti-tuberculosis treatment. We argue that adequately treated patients are still at high risk for recurrent disease and should be considered in case-finding strategies. Moreover, those with multiple risk factors may benefit from modification of standard treatment.

Delayed tuberculosis diagnosis and tuberculosis transmission.

SETTING: Tuberculosis (TB) patients and their close contacts reported to the Maryland Department of Health and Mental Hygiene from 1 June 2000 to 30 November 2001. OBJECTIVES: A recent prospective study found that 49% of pulmonary TB patients had total treatment delays > or = 90 days. This cohort was analyzed to determine the association between total treatment delay and TB transmission. DESIGN: TB patient data were collected as part of a prospective cohort study; contact data were collected from local health departments. RESULTS: Close contacts of 54 US-born patients (n = 310) and those of 70 foreign-born cases (n = 393) received tuberculin skin tests (TSTs). Among contacts of US-born patients with a total treatment delay of > or = 90 days, 40% had positive TSTs vs. 24% contacts of patients with shorter delays (aOR 2.34; P = 0.03). Other patient factors associated with TST positivity among contacts of US-born cases were black race (aOR 3.03; P = 0.05), sputum smear positive for AFB (aOR 3.29; P = 0.01) and chest radiograph with cavitation (aOR 3.11; P = 0.01). No associations were observed between foreign-born patients and risk of TST positivity among their contacts. CONCLUSION: Among US-born patients, delay in TB diagnosis is associated with greater transmission of infection to contacts and could be used independently of other index patient factors to identify contacts at greatest risk of TB infection.

A cross-sectional study of vitamin C and cognitive function in older adults: the differential effects of gender.

Previous studies have suggested that vitamin C status may be associated with cognitive function in community-dwelling populations. However, this has not been consistent across all studies due to methodological differences. This cross-sectional study assessed the association between vitamin C and cognitive function in 544 community-dwelling older adults aged 65 or older who participated in both the Cardiovascular Health Study (CHS) and the CLUE II study in 1989. Three percent of the subjects had low plasma vitamin C concentrations (< 40 mg/dL) and 15% had low total vitamin C intake (< 60 mg/day). Most participants (96.7 percent) had normal cognitive function. In the unadjusted analyses, the highest fifth of plasma vitamin C concentration was associated with better Digit Symbol Substitution Test (DSST) scores and marginally associated with Mini-Mental State Examination (MMSE) compared to the lowest fifth. Total vitamin C intake, measured by Block's food frequency questionnaire, was generally associated with higher MMSE scores, though it was not significant. Adjusting for numerous factors did not substantially change results. In a stratified analysis by gender, higher plasma concentrations or intake were associated with higher MMSE scores for men but not for women. These mixed results do not provide strong evidence of an association between vitamin C concentrations or intake and cognitive function.

BCG vaccination and the subsequent development of cancer in humans.

In 1950 approximately one-half of the population of Muscogee County, Georgia, and Russell County, Alabama, who were over the age of 5 years took part in a tuberculosis survey that included a controlled trial of BCG vaccination. A total of 16,913 persons were classed as vaccinees and 17,854 as controls. By the end of 1977, nearly 28 years later, 423 controls and 429 vaccinees were known to have developed cancer. Inasmuch as only 379 cancer cases were expected among vaccinees, there was no indication of any general protective effect of BCG vaccination against cancer. There were 18 sites with 5 or more cancers among controls and vaccinees and with observed/expected ratios greater than 1.49 or less than 0.68. Fewer cancers among vaccinees than expected were found for only 6 of these 18 sites. Among the sites with excessive cases among vaccinees was the lymphoma-Hodgkin's disease-leukemia group [International Classification of Diseases (Eighth Revision) codes 200-202, 204-207], a group suspected from previous studies of occurring more frequently after BCG vaccination.

Efficacy of BCG vaccination in prevention of cancer.

From 1949 to 1951, a total of 191,827 children in Puerto Rico were enrolled in a controlled trial of BCG vaccination. Of these children, 1 through 18 years of age, 82,269 were classified as reactors to tuberculin and 109,558 as nonreactors. Of the nonreactors, 31,856 refused vaccination, 27,338 were left unvaccinated as controls, and 50,674 were vaccinated with BCG. By the end of June 1969, a total of 37 cases of cancer had been diagnosed among the controls and 98 among the "vaccinees," yielding average annual rates of 7.2 and 10.3 cases per 100,000 population, respectively. The vaccinated group had a slight deficiency of leukemia cases and an excess of lymphosarcoma and Hodgkin's disease. The excess risk of cancer was concentrated among children age 10 through 18 on entry into the trial.

Neoplasms following childhood radium irradiation of the nasopharynx.

Eighteen to 35 years after admission to a clinic for the prevention of deafness, no increased overall cancer risk could be detected among 904 persons who had been treated with nasopharyngeal radium irradiation when compared with the risk among 2,021 persons who were either treated surgically or not treated at all, although there were differences at specific sites. An increased risk of developing both benign and malignant head and neck tumors was found among irradiated persons. Whereas no one head and neck site showed a statistically significant excess, a slight excess of brain cancer occurred 15-20 years after radium treatment. No increase in thyroid cancer risk was observed, a result possibly attributable to the low radiation doses to this organ, and the relatively small population irradiated.

Serologic precursors of cancer. Retinol, carotenoids, and tocopherol and risk of prostate cancer.

We investigated the associations of serum retinol, the carotenoids beta-carotene and lycopene, and tocopherol (vitamin E) with the risk of prostate cancer in a nested case-control study. For the study, serum obtained in 1974 from 25,802 persons in Washington County, MD, was used. Serum levels of the nutrients in 103 men who developed prostate cancer during the subsequent 13 years were compared with levels in 103 control subjects matched for age and race. Although no significant associations were observed with beta-carotene, lycopene, or tocopherol, the data suggested an inverse relationship between serum retinol and risk of prostate cancer. We analyzed data on the distribution of serum retinol by quartiles, using the lowest quartile as the reference value. Odds ratios were 0.67, 0.39, and 0.40 for the second, third, and highest quartiles, respectively.

Efficacy of BCG vaccination in prevention of cancer: an update.

From 1949 to 1951, a controlled trial of BCG vaccinations was conducted in Puerto Rico. The 191,827 children, 1-18 years of age, initially enrolled in the study were skin-tested with tuberculin to determine their eligibility for vaccination. A total of 82,269 children were classified as reactors and not vaccinated. Of the 109, 558 nonreactors, 31,586 refused vaccination, 50,634 were vaccinated with BCG, and 27,338 were left unvaccinated as controls. We ascertained the incidence of cancer over an average follow-up period of 23.3 years in the latter two groups using the Puerto Rico Central Cancer Registry. By the end of December 1973, a total of 77 cancers had been diagnosed among the controls and 150 among the vaccinees. The overall incidence of cancer among the two groups was similar. Although a number of differences existed between the vaccinee group and the controls in regard to the incidence of cancer at various "sites", none of these differences was statistically significant. However, when cases of lymphosarcoma and Hodgkin's disease were combined for analysis, a statistically significant excess of cases occurred among the vaccinees. We concluded that BCG vaccination had no protective effect on the subsequent development of cancer in this population. The slight excess of cases of lymphosarcoma and Hodgkin's disease among the vaccinees raised the possibility that BCG may have had an adverse effect.

Cigarette smoking and the risk of colorectal cancer in women.

Colorectal cancer incidence rates for smokers, nonsmokers living with smokers (i.e., passive smokers), and nonsmokers in smoke-free households were compared in a 12-year prospective study of 25,369 women who participated in a private census conducted in Washington County, MD, in 1963. Women who smoked had a decreased relative risk of colorectal cancer compared with the risk for nonsmokers (age-adjusted relative risk, 0.76; 95% confidence interval, 0.52-1.10). The risk for passive smokers was similar to that for smokers. The relative risks were significantly reduced for older women; relative risks were 0.42 for smokers and 0.66 for passive smokers over age 65. The data suggest that older women who smoke have a lower risk of colorectal cancer than nonsmokers. The effect may be mediated by an antiestrogenic effect of smoking.

Association between alpha-tocopherol, gamma-tocopherol, selenium, and subsequent prostate cancer.

BACKGROUND: Selenium and alpha-tocopherol, the major form of vitamin E in supplements, appear to have a protective effect against prostate cancer. However, little attention has been paid to the possible role of gamma-tocopherol, a major component of vitamin E in the U.S. diet and the second most common tocopherol in human serum. A nested case-control study was conducted to examine the associations of alpha-tocopherol, gamma-tocopherol, and selenium with incident prostate cancer. METHODS: In 1989, a total of 10,456 male residents of Washington County, MD, donated blood for a specimen bank. A total of 117 of 145 men who developed prostate cancer and 233 matched control subjects had toenail and plasma samples available for assays of selenium, alpha-tocopherol, and gamma-tocopherol. The association between the micronutrient concentrations and the development of prostate cancer was assessed by conditional logistic regression analysis. All statistical tests were two-sided. RESULTS: The risk of prostate cancer declined, but not linearly, with increasing concentrations of alpha-tocopherol (odds ratio (highest versus lowest fifth) = 0.65; 95% confidence interval = 0.32--1.32; P(trend) =.28). For gamma-tocopherol, men in the highest fifth of the distribution had a fivefold reduction in the risk of developing prostate cancer than men in the lowest fifth (P:(trend) =.002). The association between selenium and prostate cancer risk was in the protective direction with individuals in the top four fifths of the distribution having a reduced risk of prostate cancer compared with individuals in the bottom fifth (P(trend) =.27). Statistically significant protective associations for high levels of selenium and alpha-tocopherol were observed only when gamma-tocopherol concentrations were high. CONCLUSIONS: The use of combined alpha- and gamma- tocopherol supplements should be considered in upcoming prostate cancer prevention trials, given the observed interaction between alpha-tocopherol, gamma-tocopherol, and selenium.

Association between glutathione S-transferase M1, P1, and T1 genetic polymorphisms and development of breast cancer.

BACKGROUND: Glutathione S-transferases (GSTs) are encoded by a superfamily of genes and play a role in the detoxification of potential carcinogens. In a nested case-control study, we investigated associations between genetic variability in specific GST genes (GSTM1, GSTT1, and GSTP1) and susceptibility to breast cancer. METHODS: In 1989, a total of 32 898 individuals donated blood samples to a research specimen bank established in Washington County, MD. Genotypes of blood specimen DNA were determined for 110 of 115 women with incident cases of breast cancer diagnosed during the period from 1990 through 1995 and up to 113 of 115 control subjects. Associations between specific genotypes and the development of breast cancer were examined by use of logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: The GSTM1 homozygous null genotype was associated with an increased risk of developing breast cancer (OR = 2.10; 95% CI = 1.22-3.64), principally due to an association with postmenopausal breast cancer (OR = 2.50; 95% CI = 1.34-4.65). For GSTP1, the data were suggestive of a trend of increasing risk with higher numbers of codon 105 valine alleles (compared with isoleucine alleles); a 1.97-fold increased risk of breast cancer (95% CI = 0.77-5.02) was associated with valine/valine homozygosity. The risk of breast cancer associated with the GSTT1 homozygous null genotype was 1.50 (95 % CI = 0.76-2.95). The risk of breast cancer increased as the number of putative high-risk genotypes increased (P for trend <.001) (OR = 3.77; 95% CI = 1.10-12.88 for a combined genotype of GSTM1 null, GSTT1 null, and either GSTP1 valine heterozygosity or GSTP1 valine homozygosity). CONCLUSIONS: Our findings suggest that genetic variability in members of the GST gene family may be associated with an increased susceptibility to breast cancer.

Prospective study of serum micronutrients and ovarian cancer.

BACKGROUND: Antioxidant micronutrients, such as alpha-tocopherol (vitamin E), the carotenoids, and selenium, may protect against the development of cancer by preventing free radical damage at the cellular level. PURPOSE: A nested case--control study was conducted among donors to a serum bank to examine the association between levels of serum micronutrients and/or cholesterol and the development of ovarian cancer. METHODS: In 1974, sera were collected from 20,305 residents of Washington County, MD, over a 4-month period and stored at -70 degrees C. Serum micronutrient concentrations of women who developed ovarian cancer (case subjects, n = 35) were compared with those of women who remained free of cancer and who were matched to case subjects on age and menopausal status (control subjects, n = 67). Serum levels of retinol (vitamin A), alpha- and beta-carotene (the major provitamin A), lycopene (a carotenoid), and alpha- and gamma-tocopherol were measured using high-performance liquid chromatography. Serum selenium was measured by neutron activation analysis. Cholesterol was measured by enzymatic assay. The data were categorized into thirds and conditional logistic regression analyses were performed to determine the association between prediagnostic serum cholesterol and micronutrient levels and the development of ovarian cancer; matched odds ratios (ORs) were determined from these regression analyses. P values for trend and for interaction were calculated with the use of two-sided likelihood ratio tests. RESULTS: Higher serum alpha-tocopherol levels were associated with an increased risk of ovarian cancer (P for trend = .04); however, this association diminished after adjustment for cholesterol. Women with higher serum cholesterol levels had an increased risk of ovarian cancer compared with women in the lowest third of cholesterol levels (OR = 3.2; 95% confidence interval = 0.9-11.3). The association between serum cholesterol levels and the risk of ovarian cancer was examined, stratifying by micronutrient level. The general pattern observed was an increased risk of ovarian cancer associated with cholesterol levels greater than 200 mg/dL, regardless of the micronutrient level. Serum selenium was associated with a decreased risk of ovarian cancer only among case participants diagnosed 4 or more years after blood collections (P for trend = .02). Concentrations of carotenoids and retinol were not associated with the development of ovarian cancer. CONCLUSIONS: Selenium may have a protective role against the development of ovarian cancer. Higher serum cholesterol levels were associated with an increased risk of developing ovarian cancer; an association that persisted regardless of serum micronutrient level. IMPLICATIONS: Given the small size of this study and the inconsistency of results among the few prospective studies of ovarian cancer conducted to test these associations, replications of these findings are highly desirable.

Selenium, lycopene, alpha-tocopherol, beta-carotene, retinol, and subsequent bladder cancer.

To examine the association between serum nutrients and the development of bladder cancer we measured selenium, alpha-tocopherol, lycopene, beta-carotene, retinol, and retinol-binding protein in serum collected from 25,802 persons in Washington County, MD, in 1974. Serum samples were kept frozen at -70 degrees C. In the subsequent 12-year period, 35 cases of bladder cancer developed among participants. Comparisons of serum levels in 1974 among cases and two matched controls for each case showed that selenium was significantly lower among cases than controls (P = 0.03), lycopene was lower among cases at a borderline level of significance (P = 0.07), and alpha-tocopherol was nonsignificantly lower (P = 0.13). For selenium there was a nearly linear increase in risk with decreasing serum levels (P = 0.03). When examined by tertiles, the odds ratio associated with the lowest tertile of selenium compared to the highest tertile was 2.06. Serum levels of retinol, retinol-binding protein, and beta-carotene were similar among cases and controls. These results support a role for selenium in the prevention of bladder cancer.

Serum levels of dehydroepiandrosterone and its sulfate and the risk of developing bladder cancer.

Dehydroepiandrosterone and dehydroepiandrosterone sulfate are endogenous steroids largely produced in the adrenal cortex and excreted in the urine. Many studies have demonstrated that administration of dehydroepiandrosterone to animals protects against a variety of chemical carcinogens. Epidemiological studies suggest that the circulating levels of these steroids in humans are related to the risk of developing some cancers and of dying from atherosclerotic cardiovascular disease. We measured serum levels of both of these steroids in 35 individuals who donated serum to a community-based serum bank in 1974 and who subsequently developed bladder cancer and in 69 matched controls from the same cohort of volunteers. Prediagnostic serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate were significantly lower among cases compared with controls. The risk of developing bladder cancer increased monotonically with decreasing serum levels of both steroids. The observed associations were not affected by adjustment for smoking or the time interval between serum collection and diagnosis. These results support a role for dehydroepiandrosterone and/or dehydroepiandrosterone sulfate in the prevention of bladder cancer.

Relationship of serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate to the risk of developing postmenopausal breast cancer.

Dehydroepiandrosterone and dehydroepiandrosterone sulfate are endogenous steroids that are produced in the adrenal cortex. A number of studies have suggested that circulating levels of these hormones are related in some way to the risk of developing breast cancer. We measured serum levels of these steroids in 30 postmenopausal women who donated blood in 1974 for a community-based serum bank and who subsequently, at least 9 years later, developed breast cancer and in 59 matched controls from the same group of volunteers. Significantly elevated serum levels of dehydroepiandrosterone were found among cases prior to diagnosis compared to controls; serum levels of dehydroepiandrosterone sulfate were slightly increased among cases. In controls, current cigarette use was associated with increased serum levels of these steroids, and levels of both steroids decreased with age.

Relationship of prediagnostic serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate to the risk of developing premenopausal breast cancer.

Dehydroepiandrosterone and dehydroepiandrosterone sulfate are steroids which may be associated with the development of breast cancer. To examine the association between serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate and the risk of developing premenopausal breast cancer, we measured hormone levels in 15 women who donated blood to a community-based serum bank in 1974 and who subsequently developed premenopausal breast cancer and in 29 matched controls from the same group of volunteers. The mean serum level of dehydroepiandrosterone among cases was 10% lower than among controls. The risk of developing breast cancer for women in the highest tertile compared with the lowest tertile of serum dehydroepiandrosterone was 0.40 with a suggestion of a dose-response trend with increasing levels. No consistent association between dehydroepiandrosterone sulfate and the risk of premenopausal breast cancer was evident. In contrast to postmenopausal breast cancer, a protective effect of dehydroepiandrosterone against premenopausal breast cancer is suggested, but because of the small sample size, the results of this study need to be replicated by others.

Serum micronutrients and the subsequent risk of oral and pharyngeal cancer.

To investigate the relationship between serum micronutrients and the subsequent risk of oral and pharyngeal cancer, a nested case-control study was conducted within a cohort of 25,802 adults in Washington County, MD, whose blood samples were collected in 1974 and stored at -70 degrees C for subsequent assays. The serum levels of nutrients in 28 individuals who developed oral and pharyngeal cancer during 1975 to 1990 were compared with levels in 112 matched controls. Serum levels of all individual carotenoids, particularly beta-carotene, were lower among subjects who developed oral and pharyngeal cancer. The risks of this malignancy decreased substantially with increasing serum level of each individual carotenoid. Persons in the highest tertile of total carotenoids had about one-third the cancer risk as those in the lowest tertile. High serum levels of alpha-tocopherol also were related to a low oral cancer risk in later years, but the risks were elevated significantly with increasing serum levels of gamma-tocopherol and selenium. The findings from this study are consistent with many previous epidemiological investigations of dietary factors for oral and pharyngeal cancer and provide further evidence for the potential role of carotenoids and alpha-tocopherol in the chemoprevention of these malignancies.

An association between the allele coding for a low activity variant of catechol-O-methyltransferase and the risk for breast cancer.

Mounting evidence suggests that catechol metabolites of estradiol may contribute to the development of estrogen-induced cancers. O-Methylation, catalyzed by catechol-O-methyltransferase (COMT), inactivates catechol estrogens. COMT is polymorphic in the human population, with 25% of Caucasians being homozygous for a low activity allele of the enzyme (COMT(LL)). We hypothesized that low activity COMT may be a risk factor for human breast cancer and designed a PCR-based RFLP assay to determine COMT genotype in a cohort of 112 matched, nested case-control samples. In the total study population, the odds ratios for the association of breast cancer risk with COMT(HL) and COMT(LL) genotypes were 1.30 [confidence interval (CI), 0.66-2.58] and 1.45 (CI, 0.69-3.07), respectively. Postmenopausal COMT(LL) women had a greater than 2-fold increased risk of developing breast cancer [odds ratio (OR), 2.18; CI, 0.93-5.11]. The association of COMT(LL) with the development of postmenopausal breast cancer was stronger and statistically significant in those women with a body mass index >24.47 kg/m2 (OR, 3.58; CI, 1.07-11.98). When COMT(LL) was combined with either glutathione S-transferase (GST) M1 null or with GSTP1 Ile-105-Val/Val-105-Val (intermediate/low activity, respectively) genotypes, the risk for developing postmenopausal breast cancer was also significantly increased. Our findings suggest that the allele encoding low activity COMT may be an important contributor to the postmenopausal development of breast cancer in certain women.

Comparison of erythema and induration as results of tuberculin tests.

SETTING: Schoolchildren, tuberculosis (TB) patients, and hospital employees in Tokyo, Japan. OBJECTIVE: To compare erythema and induration resulting from tuberculin tests among TB patients, normal children, and hospital employees with and without evidence of atopy. DESIGN: The distributions of diameters of erythema and induration were compared among three groups: 951 TB patients, 6139 first-grade and 6185 seventh-grade children, and 97 volunteer employees classified as atopic or non-atopic on the basis of skin tests and serum immunoglobulin E (IgE) concentrations. RESULTS: Erythema and induration were highly correlated. The distribution of erythema diameters was unimodal, and the distribution of induration diameters was bimodal. Erythema was considerably greater than induration among persons classified as being atopic. CONCLUSION: Both erythema and induration appear to be adequate indices of tuberculin sensitivity. However, because most of the world uses induration as the index and virtually all studies of tuberculin sensitivity rely on induration, there are advantages in the use of induration. It would be desirable to initiate a large prospective study to see whether erythema or induration is the better predictor of subsequent tuberculous disease, and to confirm our finding that erythema is more likely to be confounded by atopy than induration.