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Background: Mechanical neck pain is a common condition that affects an estimated 70% of persons at some point in their lives. Little research exists to guide the choice of therapy for acute and subacute neck pain.Objective: To determine the relative efficacy of spinal manipulation therapy (SMT), medication, and home exercise with advice (HEA) for acute and subacute neck pain in both the short and long term.Design: Randomized, controlled trial. (ClinicalTrials.gov registration number: NCT00029770)Setting: 1 university research center and 1 pain management clinic in Minnesota.Participants: 272 persons aged 18 to 65 years who had nonspecific neck pain for 2 to 12 weeks.Intervention: 12 weeks of SMT, medication, or HEA.Measurements: The primary outcome was participant-rated pain, measured at 2, 4, 8, 12, 26, and 52 weeks after randomization. Secondary measures were self-reported disability, global improvement, medication use, satisfaction, general health status (Short Form-36 Health Survey physical and mental health scales), and adverse events. Blinded evaluation of neck motion was performed at 4 and 12 weeks.Results: For pain, SMT had a statistically significant advantage over medication after 8, 12, 26, and 52 weeks (P ≤ 0.010), and HEA was superior to medication at 26 weeks (P = 0.02). No important differences in pain were found between SMT and HEA at any time point. Results for most of the secondary outcomes were similar to those of the primary outcome.Limitations: Participants and providers could not be blinded. No specific criteria for defining clinically important group differences were prespecified or available from the literature.Conclusion: For participants with acute and subacute neck pain, SMT was more effective than medication in both the short and long term. However, a few instructional sessions of HEA resulted in similar outcomes at most time points.Primary Funding Source: National Center for Complementary and Alternative Medicine, National Institutes of Health. [ABSTRACT FROM AUTHOR]

Background: Weight loss and increased physical exercise reduce the risk for diabetes in people with impaired glucose tolerance. Randomized trial evidence on the effect of these interventions on people without impaired glucose tolerance is lacking.Objective: To examine the influence of a comprehensive intervention program on the risk for developing diabetes in men without impaired glucose tolerance and in a post hoc subgroup analysis by baseline cigarette smoking status.Design: Randomized, controlled trial.Setting: 22 clinical centers for the Multiple Risk Factor Intervention Trial (MRFIT).Participants: 12,866 men age 35 to 57 years at risk for cardiovascular disease were randomly assigned to either a special intervention or usual care group and followed for 6 to 7 years; this report focuses on 11,827 men without diabetes or impaired glucose tolerance at entry for whom follow-up glucose measurements were available.Measurements: Cardiovascular disease risk factors, fasting blood glucose levels, and diabetes medication history were assessed before randomization and annually.Intervention: Men in the special intervention group were counseled to change diet (reduce saturated fat, cholesterol, and calorie intake), to stop smoking, and to increase physical activity. Blood pressure was treated more intensively in the special intervention group than in the usual care group.Results: 11.5% of the special intervention group and 10.8% of the usual care group developed diabetes over 6 years of follow-up (hazard ratio, 1.08 [95% CI, 0.96 to 1.20]). The special intervention-usual care hazard ratio for diabetes was 1.26 (CI, 1.10 to 1.45) among smokers (63%) and 0.82 (CI, 0.68 to 0.98) among nonsmokers (37%). These estimates differed significantly (P = 0.0003). Weight gain after smoking cessation and the use of antihypertensive drugs may have counterbalanced the beneficial effect of the lifestyle intervention for the special intervention group smokers, while the lifestyle intervention was beneficial among nonsmokers.Limitations: Principal findings are based on a post hoc subgroup analysis.Conclusions: In nonsmokers, an intervention program that included nutrition counseling to produce reductions in weight, serum cholesterol, and (along with antihypertensive medication) blood pressure reduced the risk for diabetes. [ABSTRACT FROM AUTHOR]

The impact of smoking cessation on coronary heart disease (CHD) and lung cancer was assessed after 10.5 years of follow-up in the 12,866 men in the Multiple Risk Factor Intervention Trial (MRFIT). Those men who died of lung cancer (n = 119) were either cigarette smokers at entry or ex-smokers; no lung cancer deaths occurred among the 1,859 men who reported never smoking cigarettes. The risk of lung cancer for smokers, adjusted for selected baseline variables using a Cox proportional hazards model, increased as the number of cigarettes smoked increased (B = 0.0203, SE = 0.0076). there was not the same graded response for CHD among smokers at entry. The risk of CHD death was greater among smokers than nonsmokers (RR = 1.57)(B = -0.0034, S.E. = 0.0048). After one year of cessation, the relative risk of dying of CHD for the quitters as compared to non-quitters (RR = 0.63) was significantly lower even after adjusting for baseline differences and changes in other risk factors. The relative risk for smokers who quit for at least the first three years of the trial was even lower compared to non-quitters (RR = 0.38). However, the relative risk for lung cancer for quitters versus non-quitters was close to 1 both for quitters at 12 months and at three years. These data support the benefits of cessation in relation to CHD and are consistent with other epidemiologic studies which suggest that the lag time for a beneficial effect of smoking cessation on lung cancer may be as long as 20 years. [ABSTRACT FROM AUTHOR]

Community-based AIDS research programs were initially federally funded in 1989. Since then, the Terry Beirn Community Programs for Clinical Research on AIDS has mandated that research units develop and maintain community advisory boards to provide advice and communicate community preferences in AIDS research. Seventeen community-based AIDS research units formed community advisory boards (CABs) based on a model developed by the Community Consortium at San Francisco General Hospital. Social workers employed by these AIDS research units surveyed 267 CAB members to ascertain board characteristics and members' perceptions of program activities. Implications for social work and future research are discussed. [ABSTRACT FROM AUTHOR]

Objectives: Workers at sewage treatment plants are exposed to a complex mixture of toxins, including hydrogen sulphide (H2S). An issue of concern among sewage workers, is possible negative nervous system effects from low-level H2S exposure. Empirical neuropsychological evidence indicates both that low-dose exposure to H2S exposure affects the nervous system, and the contrary, that such exposure may facilitate nervous system function, since H2S is an endogenously produced central nervous system (CNS) gasotransmitter. The aim of this study is to describe a possible association between the H2S component of the total exposure and long-term effects on neuropsychological motor function among wastewater workers., Methods: Workers (N = 138) treating wastewater in 6 sewage-treatment plants, or in the sewer net system participated in a cross-sectional study. H2S exposure was expressed in a dichotomous exposure variable defining currently H2S-exposed (N = 112) and unexposed referent workers (N = 26), and a variable defining a job-exposure matrix for long-term total typical workplace H2S exposure. The participants went through neuropsychological tests for hand coordination, reaction time (SRT), and balance, and completed questionnaires. Pearson chi-square test or independent samples t-test was used when comparing the currently H2S-exposed workers with the unexposed control group. Multiple linear regression was used to assess associations between the independent variables age, smoking and exposure variables, and the neuropsychological tests., Results: The analyses indicate increased SRT in the currently H2S-exposed group compared to controls (mean [SD] = 225.8 [29.9] versus 210.7 [26.3] ms, P = 0.019), and an association between increased SRT and current H2S-exposure in the total study sample (β = 14.7, P = 0.026, R2 = 0.06, P = 0.050). Blindfolded balance testing indicates a nonsignificant trend in the total study sample, of reduced balance in the highest versus lowest H2S total long-term exposure-index group (Sway area [mean {SD}, mm2: 702 [410] versus 581 [278]), and a significant association between total long-term H2S exposure and reduced balance among smokers (Sway area, mm2 [β = 38.7, P = 0.039], mean sway, mm [β = 0.3, P = 0.015])., Conclusion: The observed trends and associations may be due to exposure peaks in certain work operations and pinpoint the importance of minimizing and avoiding exposure peaks, also when H2S time-weighted average measurements do not exceed an occupational exposure limit of 5 ppm., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.)

Background: The purpose of this study is to investigate whether airborne exposure to endotoxins, hydrogen sulphide (H2S), and inhalable particles negatively impacts the respiratory system and inflammatory blood proteins in sewage plant and sewer net system workers and, further, to determine dose-response associations between exposure and health outcomes., Methods: In total, 148 waste water workers (WWWs) from urban and rural sewage plants and the sewer net system participated. One hundred and twenty-one workers were exposed to sewage, 46 from sewage plants and 75 from the sewer net system. Twenty-seven workers were characterized as little or not exposed and served as an internal reference group. Personal inhalable samples were analysed for endotoxins (Limulus assay), particle dust (gravimetrically) and Salmonella and Yersinia spp. (polymerase chain reaction method, PCR). Levels of H2S were measured using personal electro chemical sensors. Intercellular adhesion molecule 1 (ICAM-1), interleukin 8 (IL-8), surfactant protein D (SP-D), club cell protein 16 (CC16), and macrophage inflammatory protein (MIP) were determined by enzyme-linked immunosorbent assay and C-reactive protein (CRP) by an HS-MicroCRP assay in blood samples., Results: Workers in sewage plants were exposed to significantly higher levels of endotoxins compared to workers in the sewer net system [median 55 EU m-3 (4-262 EU m-3) and median 27 EU m-3 (1-304 EU m-3), respectively]. The estimated H2S index showed higher values when working in the sewer net system [median 3.1 (0.5-78.1)] compared to workers at the sewage plants [median 1.3 (0.5-9.3)], and the most excessive exposure was collecting sewage from cesspools (273 p.p.m.). No viable airborne Salmonella and Yersinia spp. were detected. The exposed workers had significantly higher CRP compared to the referents [1.2 µg ml-1 (0.1-19.0 µg ml-1) and 0.8 µg ml-1 (0.1-5.0 µg ml-1), respectively] and lower forced expiratory volume in 1 s (FEV1)% [92.6%, standard deviation (SD) 14.6 and 102.0%, SD 10.1, respectively], with numbers given as mean and SD. The serum concentration of CRP was significantly and negatively associated with FEV1% (β = -7.7, R2 = 0.05) and forced vital capacity % (β = -8.5, R2 = 0.08), and the serum concentration of ICAM-1 with the estimated exposure to H2S (β = -19.9, R2 = 0.07)., Conclusion: Despite moderate levels of endotoxin and H2S exposure, the results indicate an impact of these agents on lung function and the adhesion molecule ICAM-1, and a low-grade systemic inflammation was indicated in increased levels of CRP., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.)

The incidence of ESRD is increasing rapidly. Limited information exists regarding early markers for the development of ESRD. This study aimed to determine over 25 yr the risk for ESRD associated with proteinuria, estimated GFR (eGFR), and hematocrit in men who did not have identified kidney disease and were randomly assigned into the Multiple Risk Factor Intervention Study (MRFIT). A total of 12,866 men who were at high risk for heart disease were enrolled (1973 to 1975) and followed through 1999. Renal replacement therapy was ascertained by matching identifiers with the United States Renal Data System's data; vital status was from the National Death Index. Men who initiated renal replacement therapy or died as a result of kidney disease were deemed to have developed ESRD. Dipstick urine for proteinuria, eGFR, and hematocrit were related to development of ESRD. During 25 yr, 213 (1.7%) men developed ESRD. Predictors of ESRD were dipstick proteinuria of 1+ or > or =2+ (hazard ratio [HR] 3.1 [95% confidence interval (CI) 1.8 to 5.4] and 15.7 [95% CI 10.3 to 23.9] respectively) and an eGFR of <60 ml/min per 1.73 m(2) (HR 2.4; 95% CI 1.5 to 3.8). Correlation between eGFR and serum creatinine was 0.9; the risk for ESRD with a 1-SD difference of each was identical (HR 1.21). Bivariate analysis demonstrated a 41-fold increase in ESRD risk in those with an eGFR <60 ml/min per 1.73 m(2) and > or =2+ proteinuria (95% CI 15.2 to 71.1). There was no association between hematocrit and ESRD. Other baseline measures that independently predicted ESRD included age, cigarette smoking, BP, low HDL cholesterol, and fasting glucose. Among middle-aged men who were at high risk for cardiovascular disease but had no clinical evidence of cardiovascular disease or significant kidney disease, dipstick proteinuria and an eGFR value <60 ml/min per 1.73 m(2) were strong predictors of long-term development of ESRD. It remains unknown whether intervention for proteinuria or early identification of those with chronic kidney disease reduces the risk for ESRD.

Background: Weight loss and increased physical exercise reduce the risk for diabetes in people with impaired glucose tolerance. Randomized trial evidence on the effect of these interventions on people without impaired glucose tolerance is lacking., Objective: To examine the influence of a comprehensive intervention program on the risk for developing diabetes in men without impaired glucose tolerance and in a post hoc subgroup analysis by baseline cigarette smoking status., Design: Randomized, controlled trial., Setting: 22 clinical centers for the Multiple Risk Factor Intervention Trial (MRFIT)., Participants: 12,866 men age 35 to 57 years at risk for cardiovascular disease were randomly assigned to either a special intervention or usual care group and followed for 6 to 7 years; this report focuses on 11,827 men without diabetes or impaired glucose tolerance at entry for whom follow-up glucose measurements were available., Measurements: Cardiovascular disease risk factors, fasting blood glucose levels, and diabetes medication history were assessed before randomization and annually., Intervention: Men in the special intervention group were counseled to change diet (reduce saturated fat, cholesterol, and calorie intake), to stop smoking, and to increase physical activity. Blood pressure was treated more intensively in the special intervention group than in the usual care group., Results: 11.5% of the special intervention group and 10.8% of the usual care group developed diabetes over 6 years of follow-up (hazard ratio, 1.08 [95% CI, 0.96 to 1.20]). The special intervention-usual care hazard ratio for diabetes was 1.26 (CI, 1.10 to 1.45) among smokers (63%) and 0.82 (CI, 0.68 to 0.98) among nonsmokers (37%). These estimates differed significantly (P = 0.0003). Weight gain after smoking cessation and the use of antihypertensive drugs may have counterbalanced the beneficial effect of the lifestyle intervention for the special intervention group smokers, while the lifestyle intervention was beneficial among nonsmokers., Limitations: Principal findings are based on a post hoc subgroup analysis., Conclusions: In nonsmokers, an intervention program that included nutrition counseling to produce reductions in weight, serum cholesterol, and (along with antihypertensive medication) blood pressure reduced the risk for diabetes.

Objective: Intrathecal narcotics (ITNs) are being used in some settings as a sole labor analgesic. However, they have not been directly compared to epidural analgesia., Study Design: We used a prospective observational design., Population: Eighty-two women with uncomplicated full-term pregnancies were enrolled upon analgesia request during spontaneous labor with cervical dilation 3 to 7 cm. Sixty-three chose ITNs (morphine and fentanyl), and 19 chose epidural analgesia (continuous infusion of bupivacaine and fentanyl)., Outcomes Measured: Pain scores were documented using a visual analog scale. Satisfaction and side effects were rated with Likert scales during a structured interview on the first postpartum day. Outcomes were analyzed with multivariate regression techniques., Results: Intrathecal narcotics were associated with significantly higher pain scores than was epidural analgesia during the first and second stages of labor and on an overall postpartum rating. The median effective duration of action for ITNs was between 60 and 120 minutes; however, ITNs provided excellent analgesia for a subgroup of women who delivered within 2 to 3 hours of receiving them. Although women in both groups were satisfied with their pain management, women receiving ITNs had statistically lower overall satisfaction scores., Conclusions: Within the limitations of a nonrandomized study, a single intrathecal injection of morphine and fentanyl has a shorter duration of action and provides less effective pain control than a continuous epidural infusion of bupivacaine and fentanyl. However, ITNs may have a role in settings with limited support from anesthesiologists or for women whose labors are progressing rapidly.

The high Na/low K environment of modern society is related to the genesis of hypertension and stroke. There is prior evidence of racial, geographical, and social class differences in Na and K intake and blood pressure. Baseline data from the Treatment of Mild Hypertension Study (TOMHS) was used to assess urinary Na and K excretion profiles by race, clinic geographic area, and education. Participants were adult black and white hypertensive patients from the Birmingham, Alabama, and Chicago, Illinois, area. Level of education was categorized as: less than college graduate and college graduate or more. Two overnight urine samples were collected and analyzed for Na and K at entry from 154 blacks and 281 whites. The urinary Na:K ratio was significantly higher in both blacks (5.1 v 3.8, P < .001) and whites (4.1 v 3.4, P < .005) in Birmingham compared with Chicago. This was primarily due to the lower excretion of urinary K in blacks (12.8 v 16.9 mmol/8 h, P < .01) and whites (14.0 v 16.5 mmol/8 h, P < .01). The highest urinary Na:K ratio was observed in blacks in Birmingham with lower education level; urinary Na excretion was high in blacks with a lower education level in both cities. No such differences were seen in whites. Although TOMHS was not population-based, these findings suggest the possibility that potassium intake among persons with stage 1 hypertension is related to geographic area in both blacks and whites, and sodium intake is inversely related to education level in blacks.

Proteinuria has been shown to be strongly associated with the prevalence and incidence of cardiovascular disease. It has been difficult to determine if the link is causal and independent. The mortality follow-up for the Multiple Risk Factor Intervention Trial (MRFIT) randomized cohort provides an opportunity to examine these relationships. Between 1973 and 1975, 361,662 men, ages 35 to 57, were screened for blood pressure, serum cholesterol, and cigarette smoking. Patients receiving medication for diabetes were excluded. Men in the upper 10 to 15% of coronary heart disease (CHD) risk (12,866) were randomized into the MRFIT trial. Standard casual urine dipstick determinations (Labstix) for protein were done at baseline and annually for six years. Post-trial cause-specific mortality was ascertained using the National Death Index. During the trial, 2326 (18.1%) of participants had + or higher proteinuria, and 593 (4.6%) had +2 or higher proteinuria. The presence of proteinuria during the six years of follow-up was consistently associated with higher all cause, cardiovascular disease (CVD) and CHD mortality, even after adjusting for other risk factors. The higher and more persistent the proteinuria, the greater the risk. In this data set, proteinuria is a strong and independent risk factor for CVD mortality.

In the United States, blacks have higher rates of hypertension than whites. A possible contributing factor to this higher rate of hypertension could be dietary differences between blacks and whites relating to sodium and potassium intake, which in turn could be related to socioeconomic differences between blacks and whites. Baseline data from the Treatment of Mild Hypertension Study (TOMHS) was used to assess differences in the urinary excretion of sodium and potassium, and the Na:K ratio between black and white participants, and also to explore the relationship of socioeconomic status (SES) and urinary electrolyte excretion within each ethnic group. Participants were men and women ages 45 to 69 with stage I diastolic hypertension (DBP < or = 99 mm Hg). Level of education and annual household income were used as indicators of SES. Two overnight urine samples were collected and analyzed for Na and K at entry on 172 black and 710 white participants. Blacks had a significantly higher mean Na:K ratio than whites, 4.3 v 3.6 (P < .001). This was primarily due to higher urinary Na excretion in blacks than whites, 57.8 v 52.7 mmol/8 h (P = .05). Analysis by education and income level showed that higher levels of urinary Na and Na:K in blacks than whites was restricted to those with lower education and income levels. For higher education and income levels, blacks had slightly lower levels of urinary Na and Na:K than whites. Correspondingly, education and income levels were related to urinary Na and Na:K in blacks but not in whites. This suggests that lower SES blacks could benefit from interventions to reduce dietary Na and increase dietary K, which would decrease their urinary Na:K ratio and may make them less prone to developing hypertension.

Renal effects of mild hypertension and therapy have not been established. Since urinary albumin and N-acetyl-beta-D-glucosaminidase excretions reflect renal effects of hypertension, they were related to blood pressure, other cardiovascular risk factors, cardiac target organ effects, and response to therapy in mild hypertension (diastolic blood pressure 85-99 mm Hg). Participants were from two clinics of the Treatment of Mild Hypertension Study (TOMHS), a multicenter randomized, double-blind, controlled trial. Participants received nutritional-hygienic therapy and one of five active drugs or placebo. Urinary albumin and N-acetyl-beta-D-glucosaminidase excretions were assessed prospectively using office "spot" collections from one clinic (n = 213) and retrospectively using overnight collections from the other clinic (n = 210). Relationships were determined between protein excretions and blood pressure, age, gender, race, blood glucose, cholesterol concentrations, and indices of body mass and left ventricular mass and function at baseline. Treatment effects were assessed after 3 to 12 months. Spot and overnight albumin excretions related positively to baseline systolic blood pressure by univariate analyses. Spot albumin excretion related positively to systolic blood pressure, age, creatinine clearance, and left ventricular function while overnight albumin excretion related positively to left ventricular mass and female gender by multiple regression analyses. Spot, but not overnight, albumin excretion declined significantly with active drug therapy. N-acetyl-beta-D-glucosaminidase excretion did not relate to blood pressure or decline with therapy. The combined results suggest albumin excretion correlates with blood pressure, decreases with antihypertensive drug therapy, and is associated with greater left ventricular function and mass, as well as glomerular filtration rate, even at mild levels of hypertension.

Methods: The relationship of cigarette smoking and smoking cessation to mortality was investigated among men screened for and also among those randomized to the Multiple Risk Factor Intervention Trial (MRFIT)., Results: Among the 361,662 men screened for the MRFIT, cigarette smoking was an important risk factor for all-cause, coronary heart disease (CHD), stroke, and cancer mortality. These risks, on the log relative scale, were strongest for cancers of the lung, mouth, and larynx. The excess risk associated with cigarette smoking was greatest for death from CHD. Overall, approximately one-half of all deaths were associated with cigarette smoking. Among the 12,866 randomized participants, weak positive associations with duration of cigarette smoking habit and tar and nicotine levels were found with all-cause mortality. For both SI and UC men, substantial differences in subsequent CHD (34-49%) and all-cause (35-47%) mortality were evident for men who reported cigarette smoking cessation by the end of the trial compared with those continuing to smoke. There was no evidence that lung cancer death rates were lower among cigarette smokers who quite compared with those who continued to smoke in this 10-year follow-up period., Conclusion: The data are consistent with results of previous epidemiologic studies indicating that the benefits of smoking cessation on CHD are rapid, while for lung cancer, the benefit is not evident in a 10-year follow-up period.

For men participating in the Multiple Risk Factor Intervention Trial, the authors evaluated the relation between the baseline forced expiratory volume in one second and lung cancer mortality among smokers between the third and tenth years of follow-up (1973-1974 to 1984). This measure of ventilatory function was a powerful predictor of lung cancer deaths, with rates that increased from 3.02 per 1,000 person-years in the lowest quintile of forced expiratory volume to 0.43 in the highest quintile. This relation was not weakened by adjustments for smoking dose, including number of cigarettes smoked per day, tar and nicotine content, duration of smoking, or age at onset of smoking. Nor was forced expiratory volume related to time between its determination and lung cancer death. If these observations can be verified in other studies, the forced expiratory volume in one second may identify smokers at very high risk of lung cancer and, hence, in need of more aggressive preventive approaches.

Clinical and epidemiologic studies suggest that the intake of potassium chloride lowers blood pressure. To investigate whether supplemental potassium chloride (96 mmol of microcrystalline potassium chloride a day) reduced the need for antihypertensive medication in hypertensive men on a restricted-sodium diet, we conducted a randomized, placebo-controlled, double-blind clinical trial. A total of 287 men 45 to 68 years of age, 142 given potassium chloride and 145 given placebo, were followed for an average of 2.2 years after the withdrawal of their antihypertensive medication. Men in both groups received instructions on following a low-sodium diet. Overnight urinary sodium excretion fell from 63 mmol per eight hours at base line to an average of 45 mmol per eight hours during follow-up. Participants given supplemental potassium chloride had significantly higher (P less than 0.001) serum potassium levels and urinary potassium excretion (averaging 4.5 mmol per liter and 42.5 mmol per eight hours, respectively) during follow-up than participants given placebo (4.2 mmol per liter and 20.0 mmol per eight hours). Seventy-nine participants in each group required reinstitution of antihypertensive medication according to strict indications defined by the protocol. No significant differences in systolic or diastolic blood pressure were observed between the two groups. During follow-up, systolic and diastolic blood pressure averaged 130.6 and 82.5 mm Hg, respectively, for participants given supplemental potassium, and 132.5 and 83.1 mm Hg for participants given placebo. We conclude that supplemental potassium chloride does not reduce the need for antihypertensive medication in hypertensive men on a restricted-sodium diet.

The cost and efficiency of training clinical centre staff and of duplicate data entry in clinical trials is reviewed. Training is an essential component of quality assurance programmes and it is usually carried out at regular intervals in long-term clinical trials. Initial training of staff and regular retraining is important to assure standardization and it can lead to reduced trial costs. Interim training for new staff and for remedial purposes is less efficient than regularly scheduled training sessions. Regional centres for training and the use of computer aided instruction are two ways such interim training can be made more efficient and standardized. Duplicate data entry or verification can result in a substantial reduction in data entry errors depending on the nature of the data being keyed. Selective verification should especially be considered for important fields for which consistency checks cannot be performed, that are alphabetic or that are several characters in length. Quality assurance procedures should be implemented to monitor data entry accuracy in clinical trials.

It has long been suspected that sodium and potassium intake influence blood pressure. Since both these electrolytes can be modified by diet, attention has focused on decreasing sodium intake and increasing potassium intake as a potential way of treating and preventing hypertension. Several short-term controlled clinical trials have examined the effect of supplemental potassium intake on blood pressure, but with inconsistent results. The Minnesota Mount Sinai Hypertension Trial (MSHT) is a double-blind study comparing placebo with potassium supplementation for controlling blood pressure in hypertensive men on a sodium-restricted diet over a 2-3 year follow-up period. At the time of randomization to placebo or supplemental potassium and through 12 weeks of follow-up, the patients were taking antihypertensive medication. This preliminary report compares blood pressure changes between the placebo and supplemental potassium groups over the first 12 weeks of the trial.

The Multiple Risk Factor Intervention Trial (MRFIT), conducted in 1973-1982, provided a unique opportunity to study the effect of passive smoking on men whose wives smoke. MRFIT participants who reported at entry that they had never smoked tobacco products were classified according to the smoking status of their wives. Men with wives who smoked had similar mean levels of serum thiocyanate (54.3 vs. 53.9 mumol/liter, p = 0.83) but higher mean levels of expired carbon monoxide (7.7 vs. 7.1 ppm, p = 0.001). Lower levels of pulmonary function (by maximum forced expiratory volume in one second) were also observed in these men (3,493.1 vs. 3,591.9 ml, p = 0.04). The relative risks, for men whose wives smoked compared with men whose wives did not smoke, for the endpoints coronary heart disease death, fatal or nonfatal coronary heart disease event, and death from any cause were 2.11 (p = 0.19, 95% confidence interval (CI) 0.69-6.46), 1.48 (p = 0.13, 95% CI 0.89-2.47), and 1.96 (p = 0.08, 95% CI 0.93-4.11), respectively. When smokers who quit prior to entry were included in the analyses, the relative risks, for men whose wives smoked compared with men whose wives did not smoke, for the above endpoints were 1.45 (p = 0.25, 95% CI 0.77-2.73), 1.19 (p = 0.29, 95% CI 0.85-1.65), and 1.72 (p = 0.01, 95% CI 1.12-2.64), respectively. These relative risk estimates did not change appreciably after adjusting for other baseline risk factors. The results suggest that passive exposure to cigarette smoke may have a deleterious impact on the health of nonsmokers and that nonsmokers may be at an increased risk of death through passive exposure to cigarette smoke.

Clamping of tendon fibers is a major concern in connective tissue biomechanics. We present here a new clamping method. Also the stretching procedure is different from the conventional extension until the point of failure. Thus we have used a procedure of interval stretches, where 0.01 extensions during 2.5 s are succeeded by periods of relaxation. This procedure reduces the stress on clamps and transducers which causes serious problems in conventional extensions of some older specimen. The influence of stretching rate and periods of relaxation on the observed values of stiffness has been tested and discussed. The fibers from rat tail tendons only show a minor increase in stiffness between 40 day and 90 day old animals, and do not show significant changes from the age of 90 to 240 days. The values of stiffness expressed as Young's modulus of elasticity, had maximal values of 1.2, 1.8 and 1.9 kNmm-2 at the three ages investigated. The fiber strength, however, increases dramatically, thus the ultimate value was 18 Nmm-2 for 40 day old fibers, while at 90 days and 240 days it had increased to 102 Nmm-2 and to 106 Nmm-2, respectively.

X-ray diffraction patterns of fibres from 90 day (mature) rat-tail tendons were investigated using synchrotron radiation. The specimens were kept isometric at their corresponding in vitro rest length, and effects of pH and ionic strength were studied during short X-ray exposures. The results indicate that fibrils, equilibrated in physiological Ringer prior to exposure, have segregated lateral regions of well ordered collagen molecular packing. Lowering the ionic strength or the pH to 4.0 causes an order/disorder transition during which the fibril crystallinity decreases. At pH 3.5 a dramatic increase in the lateral swelling was observed. This effect was absent for fibres pretreated with sodium borohydride. The results are interpreted on the basis of cross-linking phenomena whereby the aldimine cross-link seems to be a controlling component of the lateral packing arrangement of collagen molecules.