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John Potter

Publications and source records attributed to John Potter.

15 recordsLinked to original sources
PubMed2007

Diet and lifestyle factor associations with CpG island methylator phenotype and BRAF mutations in colon cancer.

It has been proposed that dietary factors such as folate, alcohol and methionine may be associated with colon cancer because of their involvement in DNA methylation processes. Data from a large population-based case-control study of incident colon cancer were used to evaluate whether intake of dietary, obesity, physical activity and nonsteroidal antiinflammatory drugs are associated with a CpG island methylator phenotype (CIMP). The BRAF V600E mutation and 5 CpG island markers (MINT1, MINT2, MINT31, p16 and hMLH1) were assessed in 1154 cases of colon cancer. We hypothesized that dietary factors involved in DNA methylation, cruciferous vegetables and use of aspirin/NSAIDs would be associated with CIMP-high tumors. Dietary folate, vitamins B(6) and B(12), methionine and alcohol were not associated with increased likelihood of colon tumors with the CIMP-high (2 or more markers methylated) phenotype. Dietary fiber, physical activity and aspirin and other nonsteroidal antiinflammatory drugs were inversely associated with both CIMP-low and CIMP-high tumors. Our results also suggested non-CIMP pathways as well. Obese individuals were at 2-fold increased risk of having a CIMP-low tumor. Alcohol was associated with an increased risk of tumors that were MSI+ and CIMP-low. In the presence of smoking 20 or more cigarettes per day, use of NSAIDs did not protect against a BRAF mutation. Our data suggest multiple pathways to colon cancer. They do not support a unique role for dietary folate, alcohol, vitamins B(6) and B(12) and methionine in a CpG island methylator phenotype.

Adult↗
PubMed2006

Hispanic acculturation and utilization of colorectal cancer screening in the United States.

BACKGROUND: Despite the evidence on the effectiveness of colorectal cancer (CRC) screening procedures, its use remains low, especially among Hispanics. Social-cultural factors may play a role in the underutilization of cancer screening. This study aimed to examine whether low acculturation was a risk factor for the underutilization of colorectal cancer screening in the Hispanic population. METHODS: The subjects were adults aged 50-80 years who identified themselves as Hispanic and never were diagnosed with colorectal cancer. Colorectal cancer screening utilization was assessed based on the use of at-home Fecal Occult Blood Test (FOBT) and the use of endoscopies (sigmoidoscopy, colonoscopy, or proctoscopy). Respondents who underwent a test for diagnostic purposes were excluded from the study. RESULTS: Our data showed that colorectal screening was underused in Hispanics compared to non-Hispanic Whites. There was a trend that acculturation level was inversely correlated with having an endoscopy in the past 5 years. This trend was also seen with having a FOBT in the past year or an endoscopy in the past 5 years. However, the association disappeared after adjusting for factors pertaining to utilizing other health care services. Additionally, after stratifying by gender, the association between the two variables was diluted. CONCLUSIONS: The findings show that low acculturation was associated with the underutilization of endoscopic colorectal cancer screening. This association may be related to lower utilization of health care services and/or language barriers that may contribute to the lower utilization.

Acculturation↗
PubMed2006

Factors associated with the incompliance with mammogram screening among individuals with a family history of breast cancer or ovarian cancer.

OBJECTIVE: The national guidelines recommend more intensive screening for breast cancer for women with a family history of breast or ovarian cancer. Using the data from the 2000 National Health Interview Survey (NHIS), we examined factors related to the underuse of mammogram in this population. METHOD: The study subjects were 1,215 women aged 30-79 who had a family history of breast or ovarian cancer in their first-degree relatives. According to the American Cancer Society's guidelines for breast cancer screening, having no mammogram in last year was used as an outcome for this study. Socio-demographic characteristics, health-related conditions, lifestyle factors, health behaviors, menstrual/reproductive information and health care access and utilization were analyzed to assess their relations to mammogram underuse using unconditional logistic regression method. RESULTS: The results showed that younger age, having no place to go when sick (OR = 2.2, 95% CI, 1.2-4.0), having no visits to a general doctor (OR = 1.7, 95% CI, 1.2-2.4) or medical specialist (OR = 2.2, 95% CI, 1.6-3.1) and having no influenza shot in last year (OR = 1.7, 95% CI, 1.2-2.3) increased the risk of underusing mammography screening among women who had a family history of breast or ovarian cancer. Women who had no home care from health professionals in the last year were less likely to underuse mammogram with an OR of 0.3 (95% CI, 0.1-0.6), compared with women who had. CONCLUSION: Medical care-related factors may affect the use of mammography screening in women with a family history of breast or ovarian cancer.

Adult↗
PubMed2006

Baroreflex sensitivity measured by spectral and sequence analysis in cerebrovascular disease : methodological considerations.

Baroreflex sensitivity (BRS) is impaired and of prognostic value in cerebrovascular disease. However, no studies to date have been published on the reproducibility of current methods of measuring BRS in this group. The reproducibility of sequence and spectral analysis methods were therefore assessed in subjects with cerebrovascular disease. A total of 14 subjects were assessed on 2 separate occasions at least 2 weeks apart, and beat-to-beat blood pressure (BP) and ECG trace were recorded for three 5-minute periods. These traces were then analyzed by spectral analysis using Fast Fourier Transform and sequence analysis. Reproducibility was calculated as the coefficient of variation (CV) and reproducibility coefficient (RC). There were no significant differences in heart rate, BP or BRS derived by either method between visits. Reproducibility was CV 22.2%, RC 6.04 ms/mmHg with spectral analysis, and CV 26.3%, RC 7.48 ms/mmHg for sequence analysis. There was close agreement between sequence and spectral derived BRS (r = 0.90). We have demonstrated that the use of spectral and sequence analysis to measure BRS is reproducible in subjects with cerebrovascular disease. These techniques are suitable for follow-up and intervention studies of BRS in this patient group.

Aged↗
PubMed2006

Body mass index and use of mammography screening in the United States.

BACKGROUND: Obese and underweight women may be less likely to seek cancer screening because of health status, self-perception, and body image related to non-desirable weight. This study examined the relationship between body mass index (BMI) and mammography screening, using the data from the year 2000 United States National Health Interview Survey. METHODS: This study included 7692 white and 1496 black female participants aged 40-80, who were randomly selected. Body mass index (kg/m2), based on self-reported weight and height, was compared between women with and without a mammogram in the past 2 years using logistic regression. RESULTS: Compared to women with normal body mass index, underweight and extremely obese women were more likely to have no screening mammograms in the past 2 years (odds ratio (OR) = 1.8, 95% confidence interval (CI), 1.2-2.6 for underweight women; odds ratio = 1.3, 95% confidence interval, 1.0-1.8 for extremely obese women). When data were analyzed by race, the odds ratio estimates were 1.8 for underweight white women (95% confidence interval, 1.3-2.7) and 1.4 for extremely obese white women (95% confidence interval, 1.0-1.9). The corresponding odds ratio estimates were close to 1.0 for black women. CONCLUSIONS: Underweight and extreme obesity may increase the risk of underusing screening mammography. The association between body mass index especially underweight and underuse of mammography might exist primarily in white women.

Adult↗
PubMed2006

Isolated urinary, fecal, and double incontinence: Prevalence and degree of soiling in stroke survivors.

OBJECTIVES: To investigate the prevalence of isolated urinary and fecal incontinence and double incontinence in community-living stroke survivors and to assess the degree of soiling. DESIGN: Community-based postal survey. SETTING: Leicestershire, United Kingdom. PARTICIPANTS: Sixty-four thousand seven hundred forty-nine community-dwelling residents (aged > or = 40) were randomly selected from the Leicestershire Health Authority register. Residents living in institutional settings were excluded. MEASUREMENTS: Respondents were asked about previous stroke, urinary and bowel symptoms, and general health and demographic details including age, sex, and ethnicity. Urinary incontinence was defined as leakage several times a month or more often. Major fecal incontinence was defined as soiling of underwear, outer clothing, furnishings, or bedding several times a month or more often. RESULTS: A 65% response rate to the postal survey was obtained, with the return of 39,519 eligible questionnaires; 4% (n = 1,483) reported stroke. Five percent of stroke survivors reported major fecal incontinence, with 4.3% reporting fecal and urinary incontinence and 0.8% reporting isolated fecal incontinence. Major fecal incontinence was four and a half times as prevalent in stroke survivors as in the nonstroke population, and stroke survivors were also twice as likely to report soiling of furnishings or bedding. Functional limitations influence the presence of fecal incontinence in the stroke and nonstroke population. CONCLUSION: Fecal incontinence is common in stroke survivors, and the degree of soiling can be considerable. Future research needs to explore the effect fecal incontinence can have on the lives of stroke survivors and on how it can best be managed in those living in the community.

Aged↗
PubMed2005

Hispanic acculturation and utilization of cervical cancer screening in the US.

BACKGROUND: Hispanic women have an incidence rate of invasive cervical cancer that is twice as high as that of non-Hispanic White women. Previous investigations have reported that Hispanics are less likely to utilize cancer screening services. Using data from the 2000 National Health Interview Survey, this study examined whether acculturation of Hispanic women was associated with cervical cancer screening. METHODS: The subjects included 2307 Hispanic women aged 21-70 who did not have a history of cervical cancer or a hysterectomy. Women were analyzed by acculturation level according to whether or not they ever had a Pap smear and had one in the previous year and previous 3 years. RESULTS: Acculturation levels tended to be inversely correlated with no Pap smear. Compared to lower acculturated women, women who were more acculturated were less likely to never had a Pap smear (OR = 0.86; 95% CI = 0.58-1.27 for moderate acculturated women and OR = 0.51; 95% CI = 0.29-0.89 for higher acculturated women). Similar results were found for having no Pap smear within the past 3 years (OR = 0.83; 95% CI = 0.61-1.13 for moderate acculturated women and OR = 0.73; 95% CI = 0.49-1.08 for higher acculturated women). CONCLUSION: The findings show that lower acculturation was associated with the under use of cervical cancer screening and suggest that these women might have barriers in accessing and utilizing Pap smears.

Acculturation↗
PubMed2005

Self-reported hepatitis and non-Hodgkin lymphoma: an analysis according to the time since hepatitis diagnosis.

PURPOSE: Using data from the Selected Cancers Study, the authors tested whether the association between hepatitis infection and non-Hodgkin lymphoma (NHL) varied according to the time since the diagnosis of hepatitis. METHODS: Cases were 1177 men ages 32-60 diagnosed with NHL between 1984 and 1988. Controls were men with no history of NHL who were frequency-matched to lymphoma cases by age and cancer registry (n = 1852). Interviews were conducted to collect data on risk factors including history of hepatitis. No information on types of hepatitis was obtained. RESULTS: Logistic regression analyses indicated that history of hepatitis diagnosed 3 or more years prior to the reference date was not a significant risk factor for NHL (OR [odds ratio] = 0.92, 95% CI: 0.63-1.35). In contrast, men with a history of hepatitis diagnosed within 3 years prior to the diagnosis date had more than a five-fold increased risk of NHL (OR = 5.77, 95% CI: 1.99-16.74). CONCLUSIONS: Although the study was limited by lack of information on different types of hepatitis, the increased OR for hepatitis diagnosed more closely to the NHL diagnosis suggests that the reported association between hepatitis and NHL might partly result from increased detection of NHL in patients with recently reported hepatitis virus infection.

Adult↗
PubMed2005

Lower cancer incidence in Amsterdam-I criteria families without mismatch repair deficiency: familial colorectal cancer type X.

CONTEXT: Approximately 60% of families that meet the Amsterdam-I criteria (AC-I) for hereditary nonpolyposis colorectal cancer (HNPCC) have a hereditary abnormality in a DNA mismatch repair (MMR) gene. Cancer incidence in AC-I families with MMR gene mutations is reported to be very high, but cancer incidence for individuals in AC-I families with no evidence of an MMR defect is unknown. OBJECTIVE: To determine if cancer risks in AC-I families with no apparent deficiency in DNA MMR are different from cancer risks in AC-I families with DNA MMR abnormalities. DESIGN, SETTING, AND PARTICIPANTS: Identification (1997-2001) of 161 AC-I pedigrees from multiple population- and clinic-based sources in North America and Germany, with families grouped into those with (group A) or without (group B) MMR deficiency by tumor testing. A total of 3422 relatives were included in the analyses. MAIN OUTCOME MEASURES: Cancer incidence in groups A and B (excluding the 3 affected members used to define each pedigree as AC-I) and computed age- and sex-adjusted standardized incidence ratios (SIRs) using Surveillance, Epidemiology, and End Results data. RESULTS: Group A families from both population- and clinic-based series showed increased incidence of the HNPCC-related cancers. Group B families showed increased incidence only for colorectal cancer (SIR, 2.3; 95% confidence interval, 1.7-3.0) and to a lesser extent than group A (SIR, 6.1; 95% confidence interval, 5.2-7.2) (P<.001). CONCLUSIONS: Families who fulfill AC-I criteria but who have no evidence of a DNA MMR defect do not share the same cancer incidence as families with HNPCC-Lynch syndrome (ie, hereditary MMR deficiency). Relatives in such families have a lower incidence of colorectal cancer than those in families with HNPCC-Lynch syndrome, and incidence may not be increased for other cancers. These families should not be described or counseled as having HNPCC-Lynch syndrome. To facilitate distinguishing these entities, the designation of "familial colorectal cancer type X" is suggested to describe this type of familial aggregation of colorectal cancer.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Associations among circulating sex hormones, insulin-like growth factor, lipids, and mammographic density in postmenopausal women.

OBJECTIVE: Hormone therapy use has been positively associated with mammographic density in several studies. However, few studies have examined the association between endogenous hormone levels and mammographic density. Therefore, we evaluated the relationship of endogenous sex hormones, insulin-like growth factor (IGF), and lipids with mammographic density in 88 overweight, postmenopausal women not taking hormone therapy. METHODS: Percent density and dense area were evaluated as continuous measures using a computer-assisted program. We used multiple linear regression to evaluate the associations of sex hormones, IGF, and cholesterol with mammographic density, adjusting for confounders, including adiposity. We evaluated stratification by history of hormone therapy use (former versus never) and hormone therapy latency (<5 versus > or = 5 years). RESULTS: Among former hormone therapy users, mammographic density was inversely associated with circulating levels of estrone (P = 0.01), estradiol (P = 0.003), free estradiol (P = 0.004), testosterone (P = 0.04), free testosterone (P = 0.02), androstenedione (P < 0.001), dehydroepiandrosterone (P = 0.01), and the ratio of IGF-I to its binding protein (IGF-I/IGFBP-3; P = 0.04). We found similar associations when we limited the analyses to women who had used hormone therapy within the past 5 years. We also noted positive associations of mammographic density with total cholesterol (P = 0.03) and low-density lipoprotein (P = 0.03) among former hormone therapy users. No associations were noted among women who had never used hormone therapy. CONCLUSIONS: These results suggest that there is an inverse relationship between endogenous sex hormones and mammographic density in postmenopausal women among former users of hormone therapy. This is not consistent with the hormone therapy literature and should be confirmed in larger studies.

Aged↗
PubMed2003

Reproducibility of circulatory changes to head-up tilt in healthy elderly subjects.

OBJECTIVE: to assess the reproducibility of the cardiovascular responses to head-up tilt including cardiac output, stroke volume and peripheral resistance, in healthy older subjects using non-invasive methods. PARTICIPANTS: twenty-five healthy community-dwelling volunteers with a mean age of 69+/-3 years. METHODS: the subjects underwent head-up tilt table testing on two occasions at an interval of 6 weeks. Pulse interval and blood pressure data were collected, on a beat-to-beat basis using a non-invasive monitor (Finapres, Ohmeda), during 70 degrees head-up tilt table testing and stored for analysis. ANALYSIS: the pulse interval and blood pressure data for the group were pooled and the relative changes in cardiac output, stroke volume and peripheral resistance were calculated using pulse contour analysis. RESULTS: the systolic blood pressure, pulse interval, cardiac output and stroke volume fell immediately after tilt with a rise in peripheral resistance. These responses were similar, though the baseline systolic blood pressure levels were lower at the second visit (P=0.06). CONCLUSION: these non-invasively assessed cardiovascular responses to head-up tilt in healthy older subjects show little variation between visits. The reproducibility of the responses in subjects with syncope and autonomic failure warrants further investigation.

Aged↗
PubMed2002

Direct and simultaneous analysis of sinigrin and allyl isothiocyanate in mustard samples by high-performance liquid chromatography.

A reversed-phase HPLC method for the simultaneous determination of the glucosinolate sinigrin and its major degradation product allyl isothiocyanate (AITC) was developed and used for direct analysis of aqueous extracts from Oriental mustard (Brassica juncea L.) related materials (ground and cracked seeds, powders, and bran) and from soil samples. The lowest detection limit was 0.1 microg/mL for both sinigrin and AITC). The developed method was used to trace the degradation of sinigrin to AITC in aqueous extracts. One of the major advantages of this method is the complete estimation of sinigrin content. The simultaneous analysis of both sinigrin and AITC in a single run avoided the underestimation caused by separate analyses.

Acetates↗
PubMed2002

GSTM-1 and NAT2 and genetic alterations in colon tumors.

OBJECTIVE: Phase II metabolizing enzymes such as glutathione S-transferases and N-acetyltransferase are involved in the detoxification of carcinogens. Genetic variants of genes coding for these enzymes have been evaluated as to their association with colon cancer, both as independent risk factors and as effect modifiers for associations with diet and cigarette smoking. In this study, we evaluate associations between the GSTM-1 genotype and the NAT2-imputed phenotype and acquired mutations in tumors. METHODS: Data is taken from a set of 1836 cases and 1958 controls with colon cancer who were part of a large case-control study of colon cancer and whose tumors were previously analyzed for Ki-ras, p53, and microsatellite instability (MSI). We also evaluate the modifying effects of these genetic variants with diet and cigarette smoking, factors previously identified as being associated with specific tumor alterations. RESULTS: Neither GSTM-1 nor the NAT2-imputed phenotype was independently associated with Ki-ras, p53, or MSI. Cigarette smoking significantly increased the risk of tumors involving the MSI pathway. Additionally, cigarette smoking doubled the risk of p53 transversion mutations among those who were GSTM-1 present. Cases were slightly more likely to have a p53 mutation if they frequently consumed red meat and had the imputed NAT2 intermediate/rapid phenotype relative to slow phenotype/infrequent consumers of red meat (OR 2.0, 95% CI 1.3-3.0 for intermediate/rapid). CONCLUSIONS: These data provide support that diet and cigarette smoking may be associated with specific disease pathways, although GSTM-1 and NAT2 do not independently appear to alter susceptibility to these diet and lifestyle factors.

Adult↗
PubMed1982

The Arthur case.

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Criminal Law↗