Biomedical subjects

C C Johnson

Publications and source records attributed to C C Johnson.

At least 37 records · Page 2Linked to original sources

PubMed2000

High-risk behavior among gay adolescents: implications for treatment and support.

This article contrasts the experiences of most adolescents during social and psychological development with the special challenges faced by those developing an awareness of their homosexuality. Emphasis is placed upon the interplay between societal prejudices and discrimination toward homosexuality and personal development and risk-taking behavior in gay adolescents. The implications of these life stressors for gay adolescents are also discussed in terms of their consequences for mental health policy and treatment.

Adolescent↗

PubMed1999

Race and differences in breast cancer survival in a managed care population.

BACKGROUND: African-American women with breast cancer have poorer survival than European-American women. After adjustment for socioeconomic variables, survival differences diminish but do not disappear, possibly because of residual differences in health care access, biology, or behavior. This study compared breast cancer survival in African-American and European-American women with similar health care access. METHODS: We measured survival in women with breast cancer who are served by a large medical group and a metropolitan Detroit health maintenance organization where screening, diagnosis, treatment, and follow-up are based on standard practices and mammography is a covered benefit. We abstracted data on African-American and European-American women who had been diagnosed with breast cancer from January 1986 through April 1996 (n = 886) and followed these women for survival through April 1997 (137 deaths). RESULTS: African-American women were diagnosed at a later stage than were European-American women. Median follow-up was 50 months. Five-year survival was 77% for African-American and 84% for European-American women. The crude hazard ratio for African-American women relative to European-American women was 1.6 (95% confidence interval [CI] = 1.1-2.2). Adjusting only for stage, the hazard ratio was 1.3 (95% CI = 0.9-1.9). Adjusting only for sociodemographic factors (age, marital status, and income), the hazard ratio was 1.2 (95% CI = 0.8-1.9). After adjusting for age, marital status, income, and stage, the hazard ratio was 1.0 (95% CI = 0.7-1.5). CONCLUSION: Among women with similar medical care access since before their diagnoses, we found ethnic differences in stage of breast cancer at diagnosis. Adjustment for this difference and for income, age, and marital status resulted in a negligible effect of race on survival.

Adult↗

PubMed1999

Complete sequence of the 23-kilobase human COL9A3 gene. Detection of Gly-X-Y triplet deletions that represent neutral variants.

We report the complete sequence of the human COL9A3 gene that encodes the alpha3 chain of heterotrimeric type IX collagen, a member of the fibril-associated collagens with interrupted triple helices family of collagenous proteins. Nucleotide sequencing defined over 23,000 base pairs (bp) of the gene and about 3000 bp of the 5'-flanking sequences. The gene contains 32 exons. The domain and exon organization of the gene is almost identical to a related gene, the human COL9A2 gene. However, exon 2 of the COL9A3 gene codes for one -Gly-X-Y- triplet less than exon 2 of the COL9A2 gene. The difference is compensated by an insertion of 9 bp coding for an additional triplet in exon 4 of the COL9A3 gene. As a result, the number of -Gly-X-Y- repeats in the third collagenous domain remains the same in both genes and ensures the formation of an in-register triple helix. In the course of screening this gene for mutations, heterozygosity for separate 9-bp deletions within the COL1 domain were identified in two kindreds. In both instances, the deletions did not co-segregate with any disease phenotype, suggesting that they were neutral variants. In contrast, similar deletions in triple helical domain of type I collagen are lethal. To study whether alpha3(IX) chains with the deletion will participate in the formation of correctly folded heterotrimeric type IX collagen, we expressed mutant alpha3 chains together with normal alpha1 and alpha2 chains in insect cells. We show here that despite the deletion, mutant alpha3 chains were secreted as heterotrimeric, triple helical molecules consisting of three alpha chains in a 1:1:1 ratio. The results suggest that the next noncollagenous domain (NC2) is capable of correcting the alignment of the alpha chains, and this ensures the formation of an in-register triple helix.

Amino Acid Sequence↗

PubMed1999

Smoking and Parkinson's disease: a dose-response relationship.

OBJECTIVE: To determine whether an inverse dose-response relationship exists between cigarette smoking and PD among ever-smokers and ex-smokers. METHODS: Smoking and alcohol consumption were analyzed in 144 PD patients and 464 control subjects, who were frequency matched for sex, race, and age (+/-5 years), in a population-based case-control study of men and women > or =50 years old in the Henry Ford Health System. RESULTS: With never-smokers as the reference category, there was an inverse association between current light smokers (>0 to 30 pack-years) and PD patients (odds ratio [OR], 0.59; 95% CI, 0.23 to 1.53), and a stronger inverse association of PD with current heavy smokers (>30 pack-years; OR, 0.08; 95% CI, 0.01 to 0.62). When former >30-pack-year smokers were stratified by the interval since quitting, there was an inverse association between those who stopped >20 years ago and PD (OR, 0.86; 95% CI, 0.42 to 1.75), and a greater inverse relationship with those who stopped 1 to 20 years ago (OR, 0.37; 95% CI, 0.19 to 0.72). Alcohol consumption had no independent, significant association with PD, but heavy drinking (>10 drink-years) had a greater effect than light-moderate drinking in reducing but not eliminating the inverse association between smoking and PD. CONCLUSIONS: The inverse dose-response relationship between PD and smoking and its cessation is unlikely to be due to bias or confounding, as discussed, providing indirect evidence that smoking is biologically protective.

Aged↗

PubMed1999

Evaluation of air and dust sampling schemes for Fel d 1, Der f 1, and Der p 1 allergens in homes in the Detroit area.

BACKGROUND: Studies often use a point estimate of allergen exposure without fully justifying the accuracy of this single measure as an estimate of total exposure. Many studies have reported relationships between indoor allergen concentrations and manifestations of allergic disease on the basis of single samples. OBJECTIVES: The purposes of this study were to (1) characterize the variability in dust and air concentrations of allergens, (2) assess the relationships between dust and air concentrations of allergens, and (3) determine the minimum number and timing of samples to characterize annual indoor allergen exposure. METHODS: As part of a prospective cohort study of asthma in children, air and dust samples were repeatedly obtained from the homes of children residing in suburban Detroit, Michigan. Concentrations of Fel d 1, Der f 1, and Der p 1 were measured in the samples. The results of various patterns of sampling were compared with yearly averages. RESULTS: The concentrations of all 3 allergens in both air and dust varied widely both within and between homes. The allergen concentrations had peak concentrations in the fall. There was little correlation between air and dust concentrations. Our results indicate that as few as 2 or 3 samples taken late in the year provide good estimates of the annual average concentrations. CONCLUSIONS: Two or 3 samples, obtained 1 month apart and taken late in the year, represent the best balance between sampling effort and accuracy of the yearly exposure estimates of Fel d 1, Der f 1, and Der p 1 in temperate climates similar to those of Detroit, Michigan.

Air Pollution↗

PubMed1999

Adult nutrient intake as a risk factor for Parkinson's disease.

BACKGROUND: This population-based case-control study evaluated nutrient intake as a risk factor for Parkinson's disease (PD) among people aged > or =50 years in metropolitan Detroit. METHODS: Cases (n = 126) were diagnosed between 1991 and 1995 and neurologist-confirmed. Controls (n = 432) were frequency-matched for sex, age (+/-5 years) and race. Using a standardized food frequency questionnaire, subjects reported the foods they ate within the past year. RESULTS: Estimating the association between PD and risk of being in the highest versus the lowest intake quartile, there were elevated odds ratios for total fat (OR 1.94, 95% confidence interval [CI] : 1.05-3.58), cholesterol (OR 2.11, 95% CI: 1.14-3.90), lutein (OR 2.52, 95% CI: 1.32-4.84) and iron (OR 1.88, 95% CI: 1.05-3.38). CONCLUSIONS: These results suggest an association of PD with high intake of total fat, saturated fats, cholesterol, lutein and iron.

Aged↗

PubMed1999

A family history of Parkinson's disease and its effect on other PD risk factors.

Parkinson's disease (PD) is likely a result of both inherited and exogenous factors. In a study of 144 PD cases and 464 controls, we used PD family history as a surrogate for inherited PD susceptibility. Cases were more likely to report a first- or second-degree relative with PD: 16.0 vs. 4.3%; odds ratio (OR) = 4. 2; 95% confidence interval (CI) = 2.3-7.6. A PD family history was a greater risk factor for PD in subjects under age 70 (OR = 8.8; 95% CI = 3.4-22.8) compared with those over 70 (OR = 2.8; 95% CI = 1.3-6. 1) and in men (OR = 8.1; 95% CI = 3.4-19.2) compared with women (OR = 2.6; 95% CI = 1.1-6.0). We also tested whether a PD family history modified the effects of other PD risk factors. In subjects with a PD family history, occupational exposure to copper, lead or iron increased the risk for PD (OR = 3.0; 95% CI = 0.7-13.3), but this was not the case for those without a family history (OR = 1.1; 95% CI = 0.7-1.6). Ever smoking cigarettes was inversely associated with PD in those without a PD family history (OR = 0.6; 95% CI = 0.4-0.9), but was positively associated with PD in those with a PD family history (OR = 1.7; 95% CI = 0.5-5.9). In summary, our results suggest that a PD family history, and perhaps, therefore, an inherited susceptibility, confers a greater risk for PD in men and individuals under 70 years of age and may modify the effects of environmental risk factors for PD.

Adult↗

PubMed1999

Patterns and characteristics of repeat mammography among women 50 years and older.

Whereas efforts encouraging women to obtain initial mammograms are laudable, the importance of returning for subsequent routine mammograms cannot be minimized. The purpose of this study was to measure the timing, patterns, and characteristics of repeat screening mammography over time in a defined population of health maintenance organization members for whom mammography was a fully covered benefit. We identified all women ages 50-74 years who were enrolled in a southeastern Michigan health maintenance organization, assigned to a large medical group, and received at least one screening mammogram with a normal result between January 1, 1989 and December 31, 1996. Using administrative and radiology data, we calculated the proportion of women who received a subsequent mammogram within 2 years and the time to subsequent screening, both overall and stratified by demographic characteristics. We also examined screening patterns over a 5-year period. Of the 8749 women included in this study, 66.0% [95% confidence interval (CI), 65.0-67.0%] were subsequently screened within 2 years. We found slightly higher rates among Caucasians and married women. The proportion of women who received repeat mammography increased with estimated household income [9.5% difference between the highest and lowest categories (95% CI, 6.5-12.5%)]. The median time to subsequent screening was 17.7 months, and the probability of repeat screening was higher for women whose initial mammogram was between January 1992 and December 1994 compared to those receiving an initial mammogram between January 1989 and December 1991 (9.6% difference; 95% CI, 7.5-11.7%). Repeat mammography has improved over time; however, socioeconomic status could contribute to longer-than-intended intervals between screening when translated into real-world clinical practice. In a setting where most physicians recommended annual screening, we found that the median time to subsequent screening was delayed by 6 months. If annual mammography is the goal, recommendations should be made with the understanding of how the timing of repeat screening occurs in clinical practice.

Aged↗

PubMed1998

Gender differences in total and allergen-specific immunoglobulin E (IgE) concentrations in a population-based cohort from birth to age four years.

While serum immunoglobulin E (IgE) concentration has been shown to be related to allergic disease, there have been few studies of the natural history of IgE development in young children. This study compared total and allergen-specific serum IgE concentrations, by gender, from birth through 4 years of age using a population-based cohort of normal children followed from 1987 to 1993. Subjects were enrolled from a geographically defined area through membership in a large health maintenance organization, and they resided in the northern suburbs of Detroit, Michigan. Total IgE concentrations were measured at birth and at 2 and 4 years of age. Specific IgE concentrations to selected common inhalant allergens (dust mite (Dematophagoides farinae), cat, ragweed (Ambrosia artemisiifolia), and timothy grass (Pheleum pratense)) were measured at 2 and 4 years of age. Total IgE increased with age from birth to 4 years for boys and girls, and was higher in boys at 2 and 4 years of age. Girls demonstrated significant increases in IgE to mite and cat and decreases in IgE to ragweed and timothy from 2 to 4 years of age, whereas there was little change for boys except an increase in IgE to ragweed. Differences in IgE development between young boys and girls may partially account for the higher prevalence of asthma in boys than in girls.

Age Factors↗

PubMed1998

Racial differences in emergency department use persist despite allergist visits and prescriptions filled for antiinflammatory medications.

BACKGROUND: African-American children use the emergency department (ED) for asthma care more than their Caucasian counterparts. OBJECTIVE: We sought to compare ED utilization for asthma care by race, adjusting for prescriptions filled for antiinflammatory medications, type of index visit (specialist vs nonspecialist), and demographic variables. METHODS: An index asthma visit was identified for a cohort of managed care enrollees aged 4 to 11 years. Information on asthma encounters and drug claims data was evaluated during a prospective observation period of 12 months. RESULTS: African-American race was associated with one or more ED visits during the observation period (relative risk [RR] = 1.8, 95% CI = 1.3 to 2.5, p < 0.01). After adjusting for index visit type, prescriptions filled, and selected demographic variables, African-American race remained associated with post-index ED utilization (adjusted RR = 1.6, 95% CI = 1.0 to 2.4, p = 0.05). Additional findings included an inverse relationship between African-American race and antiinflammatory medications among children with nonspecialist index visits (RR = 0.5, 95% CI = 0.3 to 0.9, p = 0.02) and a positive relationship between African-American race and hospitalization after an ED visit for asthma care (RR = 10.2, 95% CI = 1.4 to 74.8, p < 0.01). CONCLUSION: African-American children were more likely to use ED asthma care even after adjusting for the type of index visit, prescriptions filled for antiinflammatory medications, and selected demographic variables. Racial differences in ED utilization for asthma care could be caused by a higher prevalence of uncontrolled or undertreated disease among African-American children not receiving specialty care.

Anti-Inflammatory Agents↗

PubMed1998

Intra- and inter-rater agreement in the assessment of occupational exposure to metals.

BACKGROUND: Among the methods of retrospective occupational exposure assessment, expert review is considered the most accurate. Although expert review provides a more objective measure of exposure, depending on the exposure of interest it may still result in a significant degree of misclassification. METHODS: To evaluate the reliability in occupational metal exposure assessment by expert review, we analysed job history data from a case-control study of a neurological disease. First, one industrial hygienist (IH) did an initial exposure assessment of the metals copper, iron and lead, blinded to case-control status, for 608 subjects who had 3033 total jobs. We then compared exposure assessments from the original review with a second blinded review of 60 job histories (306 jobs) by the same IH (intra-rater) and of 64 job histories (361 jobs) by a different IH (inter-rater). RESULTS: The per cent agreements for the intra-IH comparisons were 89.6 for copper, 87.9 for iron and 94.6 for lead, whereas the inter-IH per cent agreements were 86.4 for copper, 81.1 for iron and 76.2 for lead. Based on the assumption that reliability is related to validity, we calculated an estimate of misclassification of metal exposure by one IH. Our exposure misclassification estimates show a sizable attenuation of the odds ratio, with the expected bias similar for copper and iron when using either intra- or inter-reliability results to estimate misclassification. CONCLUSION: Our results suggest that variation in the expert assessment of metal exposure is due mainly to the difficulties involved in transforming an occupational history into an estimate of exposure.

Aged↗

PubMed1998

The transepicondylar axis approximates the optimal flexion axis of the knee.

The traditional understanding of knee kinematics holds that no single fixed axis of rotation exists in the knee. In contrast, a recent hypothesis suggests that knee kinematics are better described simply as two simultaneous rotations occurring about fixed axes. Knee flexion and extension occurs about an optimal flexion axis fixed in the femur, whereas tibial internal and external rotations occur about a longitudinal rotation axis fixed in the tibia. No other translations or rotations exist. This hypothesis has been tested. Tibiofemoral kinematics were measured for 15 cadaveric knees undergoing a realistic loadbearing activity (simulated squatting). An optimization technique was used to identify the locations of the optimal flexion and longitudinal rotation axes such that simultaneous rotations about them could best represent the measured kinematics. The optimal flexion axis was compared with the transepicondylar axis defined by bony landmarks. The longitudinal rotation axis was found to pass through the medial joint compartment. The optimal flexion axis passed through the centers of the posterior femoral condyles. No significant difference was found between the optimal flexion and transepicondylar axes. To an average accuracy of better than 3.4 mm in translation, and 2.9 degrees in orientation, knee kinematics were represented successfully by simple rotations about the optimal flexion and longitudinal rotation axes. The optimal flexion axis is fixed in the femur and can be considered the true flexion axis of the knee. The transepicondylar axis axis, which is identified easily by palpation, closely approximates the optimal flexion axis.

Adult↗

PubMed1998

Outcomes of a high school program to increase fruit and vegetable consumption: Gimme 5--a fresh nutrition concept for students.

This paper describes an intervention to increase high school students' fruit and vegetable consumption. Twelve schools were randomized to intervention or control conditions. The cohort (2,213 students; 56% females, 84% Caucasian) were followed from 9th to 12th grades. Interventions comprised a media campaign, classroom workshops, school meal modification, and parental support. Usual daily servings of fruit/vegetables increased 14% in the intervention compared to the control group (p > 0.001) the first three years. At follow-up, consumption within the control group also increased, resulting in no significant difference between groups. Intervention group knowledge scores and awareness indicators were significantly higher than those of the control group (p < 0.0001). Gimme 5 provided a first model to show that dietary habits of high school students can be influenced by positive media messages relative to that age group, increased exposure to a variety of tasty products, and minimal classroom activity.

Adolescent↗

PubMed1998

The risk of Parkinson's disease with exposure to pesticides, farming, well water, and rural living.

We assessed exposure to pesticides, farming, well water use, and rural living as risk factors for Parkinson's disease (PD) in a population-based case-control study consisting of men and women > or = 50 years of age who had primary medical care at Henry Ford Health System in metropolitan Detroit. Enrolled PD patients (n = 144) and control subjects (n = 464) were frequency-matched for age, race, and sex. When adjusted for these variables and smoking status, there was a significant association of occupational exposure to herbicides (odds ratio [OR], 4.10; 95% CI, 1.37, 12.24) and insecticides (OR, 3.55; 95% CI, 1.75, 7.18) with PD, but no relation was found with fungicide exposure. Farming as an occupation was significantly associated with PD (OR, 2.79; 95% CI, 1.03, 7.55), but there was no increased risk of the disease with rural or farm residence or well water use. The association of occupational exposure to herbicides or insecticides with PD remained after adjustment for farming. The association of farming with PD was maintained after adjustment for occupational herbicide exposure and was of borderline significance after adjustment for occupational insecticide exposure. These results suggest that PD is associated with occupational exposure to herbicides and insecticides and to farming and that the risk of farming cannot be accounted for by pesticide exposure alone.

Agricultural Workers' Diseases↗

PubMed1997

Cancer incidence among an HIV-infected cohort. Pulmonary Complications of HIV Infection Study Group.

Malignancies, particularly Kaposi's sarcoma and non-Hodgkin's lymphoma (NHL), are associated with human immunodeficiency virus (HIV) infection. Cancer incidence among 1,073 asymptomatic HIV-infected individuals from the Pulmonary Complications of HIV Infection Study cohort, persons from six states followed from 1988 to 1994, was examined. Total cancer incidence was 3.99/100 person-years; for Kaposi's sarcoma, incidence was 2.64 cases/100 person-years, and for NHL, it was 1.18 cases/100 person-years. Total cancer (n = 156 cases) was higher among nonblacks than among blacks (rate ratio = 2.8, 95% confidence interval 1.3-6.1), with similar results for Kaposi's sarcoma and NHL. The rate of lung cancer (n = 5) among white, homosexual/bisexual males was 0.18 per 100 person-years, suggesting a high risk of lung cancer.

Adult↗

PubMed1997

School-based programs for health-risk reduction.

Based on implications from the pediatric studies of cardiovascular risk, it has become imperative that practical methods be developed to begin prevention of heart disease early in life. Schools provide an excellent setting for introducing comprehensive health education and promotion as a public health approach to the general population. A number of school-based health education programs have been developed (Heart Ahead/Heart Smart, CATCH, Gimme 5) for children in kindergarten through high school, in which education and environmental changes have been shown to be effective in promoting healthful behaviors. The effective implementation of health education depends to a large extent on the training and motivation of teachers, administrators, and food service staff. Training Institutes can be important for increasing personal awareness, disseminating information and materials, motivating health education efforts for teachers, food service staff and their students, and evaluating the health risk of school personnel.

Adolescent↗

PubMed1997

Effect of test environment on intervertebral disc hydration.

STUDY DESIGN: Water content of fresh human lumbar intervertebral discs (with adjacent endplates) was assessed in three studies: 1) after each of seven specimen preparation steps. 2) during exposure to either saline spray or a saline bath, and 3) during exposure to a saline bath and 445 N axial compression, either without or with previous exposure to the bath and no compression ("free swelling"). OBJECTIVE: To assess the effect on disc hydration of various aspects of specimen preparation and testing environments. SUMMARY OF BACKGROUND DATA: Water content is an important determinant of disc behavior. Specimen preparation method and testing environments may be important determinants of water content, yet no work appears to have been reported specifically on this topic. METHODS: Endplate-disc-endplate specimens were prepared from refrigerated cadavers within 24 hours of death by transverse sectioning of adjacent vertebral bodies. Water content change was determined by specimen weight change across each time interval of interest. RESULTS: Specimen preparation (including multiple freeze-thaw cycles) produced no water content change. Saline spray and plastic film wrap resulted in no change, but saline bath exposure resulted in a 24% increase over 7 hours, 44% of which occurred in the first 0.5 hour. A subsequent 7 hours of 445 N compression reduced the overall increase to 10%. This was not significantly different from the 8% increase that resulted from initial exposure to saline bath and compression. CONCLUSIONS: Specimen preparation as typically performed and specimen exposure to saline spray and plastic film wrap do not result in hydration change. Exposure to saline bath results in substantial swelling, which can either be reversed or prevented by axial compression in the physiologic range. Whether discs exposed to saline spray and wrap without compression and those exposed to saline bath with compression behave the same and which of these more closely mimics the in vivo condition are important issues for the experimentalist to test.

Adult↗

PubMed1997

Comparability of different methods of retrospective exposure assessment of metals in manufacturing industries.

Many occupational case-control studies have relied on either self-report or exposure assessment based on job titles linked to a job exposure matrix (JEM) as opposed to the generally considered more accurate, but labor intensive, method of expert review of job histories. Our study examined the comparability of these different methods in assessing occupational exposure to the metals copper (Cu), lead (Pb), and iron (Fe) in manufacturing industries. Subjects were older people from a case-control study of a neurologic disease, and consisted of 188 individuals (72% male, 85% white) who had worked an average of 22.4 years in the manufacturing industry. An industrial hygienist review (IHR) of occupational history data from a comprehensive questionnaire was used as the reference method. The percent agreement (%A), sensitivity (SE), and specificity (SP) for direct self-report of metal exposures were: Cu, %A = 94.6, SE = 83.6, SP = 96.1; Pb, %A = 91.9, SE = 72.5, SP = 93.5; and Fe, %A = 82.7, SE = 64.5, SP = 88.1. Using the National Institute for Occupational Safety and Health (NIOSH) JEM, we analyzed the jobs of 115 of the 188 study subjects who had all their jobs listed in the JEM. Exposure assessment based on the NIOSH JEM compared with the IHR resulted in greater misclassification relative to direct self-report: Cu, %A = 81.5, SE = 21.2, SP = 89.2; Pb, %A = 86.0, SE = 0.0, SP = 92.6; and Fe, %A = 69.2, SE = 15.5, SP = 86.4. For all three study metals, combining the information from both direct self-report and the JEM did not improve upon the results compared with direct self-report alone. Due to the complex nature of metal exposure assessment, we suggest using an expert review of job histories whenever possible to minimize potential misclassification.

Aged↗