Search

To examine the relationship between acyclovir use and survival in AIDS, we performed a retrospective analysis of data collected through an observational cohort of the 17-site Community Program for Clinical Research on AIDS (CPCRA), under the sponsorship of the National Institute of Allergy and Infectious Diseases. Data were analyzed regarding 2,368 patients with CD4+ lymphocyte counts of < 500/mm3, and 7,836 follow-up visits were conducted from September 1990 to July 1994. Factors associated with use of acyclovir were studied by stratified analysis of variance and Mantel-Haenzel chi 2 tests. The association between acyclovir and survival was studied with use of the proportional hazards regression model. Individuals reporting acyclovir use were more likely to be white, male, and homosexual; to have a history of herpes simplex and zoster; and to have lower CD4+ T cell counts than those who did not. After adjustments for differences in baseline factors, acyclovir use was not associated with prolonged survival.

Murine coronavirus MHV-A59 normally infects only murine cells in vitro and causes transmissible infection only in mice. In the 17 C1 1 line of murine cells, the receptor for MHV-A59 is MHVR, a biliary glycoprotein in the carcinoembryonic antigen (CEA) family of glycoproteins. We found that virus released from the 600th passage of 17 C1 1 cells persistently infected with MHV-A59 (MHV/pi600) replicated in hamster (BHK-21) cells. The virus was passaged and plaque-purified in BHK-21 cells, yielding the MHV/BHK strain. Because murine cells persistently infected with MHV-A59 express a markedly reduced level of MHVR (Sawicki, et al., 1995), we tested whether virus with altered receptor interactions was selected in the persistently infected culture. Infection of 17 C1 1 cells by MHV-A59 can be blocked by treating the cells with anti-MHVR MAb-CC1, while infection by MHV/BHK was only partially blocked by MAb-CC1. MHV/BHK virus was also more resistant than wild-type MHV-A59 to neutralization by purified, recombinant, soluble MHVR glycoprotein (sMHVR). Cells in the persistently infected culture may also express reduced levels of and have altered interactions with some of the Bgp-related glycoproteins that can serve as alternative receptors for MHV-A59. Unlike the parental MHV-A59 which only infects murine cells, MHV/BHK virus was able to infect cell lines derived from mice, hamsters, rats, cats, cows, monkeys and humans. However, MHV/BHK was not able to infect all mammalian species, because a pig (ST) cell line and a dog cell line (MDCK I) were not susceptible to infection. MHV/pi600 and MHV/BHK replicated in murine cells more slowly than MHV-A59 and formed smaller plaques. Thus, in the persistently infected murine cells which expressed a markedly reduced level of MHVR, virus variants were selected that have altered interactions with MHVR and an extended host range. In vivo, in mice infected with coronavirus, virus variants with altered receptor recognition and extended host range might be selected in tissues that have low levels of receptors. Depending upon the tissue in which such a virus variant was selected, it might be shed from the infected animal or eaten by a predator, thus presenting a possible means for initiating the transition of a variant virus into a new host as a model for an emerging virus disease.

Many persons with HIV require and take several medications. The efficacy and safety of many of these medications are uncertain. Usually limited data on drug interactions are available. Thus simultaneous and sequential enrolment of patients into multiple studies is desired for reasons of science and efficiency. This paper discusses the analysis of data arising from coenrolment in multiple studies sponsored by the Community Programs for Clinical Research on AIDS (CPCRA). Factorial designs and those in which patients are sequentially instead of simultaneously randomized are compared. Approaches to data analysis, based on intention-to-treat, for individual and pairs of trials are described. An antiretroviral trial and a trial for prophylaxis of Pneumocystis carinii pneumonia (PCP) are used for illustration. We conclude that such analyses may yield useful information on drug interactions and that a more vigorous coenrolment policy should be pursued in AIDS research.

Background: Reduced parathyroid sensitivity to changes in calcium (Ca2+) has been observed in patients treated with lithium (Li+). In order to investigate this desensitization phenomenon, the effect of Li+ on cytosolic calcium (Cai2+) regulation was examined., Methods: Transmembrane signal transduction and Ca2+ sequestration were investigated in bovine parathyroid cells by measuring changes in [Cai2+] in response to 5 mmol/L magnesium (Mg2+), 0.5 to 2.5 mmol/L Ca2+, 25 mumol/L adenosine triphosphate (ATP), and 1 mumol/L ionomycin in cells pretreated with 1 to 10 mmol/L lithium chloride (LiCl) and control cells. Measurement of Cai2+ was made using fura-2., Results: Increases in [Cai2+] in response to Ca2+ and Mg2+ were blunted following overnight culture with as low as 1 mmol/L LiCl. In normocalcemic medium, 1 mmol/L Ca2+ produced an 81% increase in [Cai2+] in control cells compared with a 58% increase in cells pretreated with LiCl (P < 0.01), whereas in hypocalcemic medium, increases in [Cai2+] were similar in lithium-treated and control cells (78% versus 82%, P > 0.1). The ATP produced increases in [Cai2+] from 225 +/- 9 nmol/L to 366 +/- 10 nmol/L in control cells, compared with 221 +/- 7 nmol/L to 308 +/- 10 nmol/L in cells pretreated with 5 mmol/L LiCl (P < 0.01). Ionomycin-induced increases in [Cai2+] were unaffected by Li+., Conclusions: We concluded that the in vitro desensitizing effects of Li+ occur at therapeutic concentrations, but only in the presence of Ca2+ in concentrations that induce transmembrane signaling; and that Li+ blunts increases in [Cai2+] related to cation and ATP-induced transmembrane signal transduction without affecting ionomycin-releasable Ca2+ stores.

In most clinical trials of antiretroviral therapy for patients infected with HIV, the major outcome variable has been the combined clinical endpoint of any new or recurrent AIDS defining event. We review features of combined endpoints and use data from the Terry Beirn Community Programs for Clinical Research on AIDS (CPCRA) to evaluate this outcome measure in terms of relevance, diagnostic certainty and sensitivity. We conclude that this endpoint is not relevant because: (i) the 19 different events constituting the combined endpoint are equally weighted in analyses even though they vary considerably in terms of risk of death; and (ii) events after the first are ignored, thus the event profile of patients is not taken into account in making treatment comparisons. We also conclude that power may be low with use of this endpoint if treatments under study do not have an immediate impact on disease progression, if some events which occur soon after randomization represent a disease process that has already begun to incubate, or if treatment differences for the various events constituting the combined endpoint are differentially effected by treatment. Since the ease and certainty of diagnosis of each of the 19 events also vary, we recommend that survival be the primary endpoint of antiretroviral trials, and that all opportunistic events experienced by patients, not just the first, be collected and summarized. Trial reports should include comparisons of incidence of each event by treatment group so that readers can rank events as they please. A single summary measure which considers severity and the entire event profile, as described here, would also be useful for assessing the impact of treatments on quality of life. Further research on approaches for weighting and combining multiple outcome measures is needed.

Background: Hypocalcemia is a common sequela of thyroidectomy; however, its causative factors have not been completely delineated., Methods: A prospective study of 60 patients who underwent unilateral (n = 15) or bilateral (n = 45) thyroidectomy between 1990 and 1993 was completed to determine the incidence and risk factors for hypocalcemia. Free thyroxine, thyrotropin, and alkaline phosphatase levels were obtained before operation in all patients, together with preoperative and postoperative ionized calcium, parathyroid hormone (PTH), calcitonin, and 1,25-dihydroxyvitamin D3 levels. All patients were examined for age, gender, extent of thyroidectomy, initial versus reoperative neck surgery, weight and pathologic characteristics of resected thyroid tissue, substernal thyroid extension, and parathyroid resection and autotransplantation., Results: Hypocalcemia, defined by an ionized calcium level less than 4.5 mg/dl, occurred in 28 patients (47%), including nine (15%) symptomatic patients who required vitamin D and/or calcium for 2 to 6 weeks. In no patient did permanent hypoparathyroidism develop. With a multivariate logistic regression analysis, factors that were predictive of postoperative hypocalcemia included an elevated free thyroxine level (p = 0.003), cancer (p = 0.010), and substernal extension (p = 0.046)., Conclusions: Postoperative decline in parathyroid hormone was not an independent risk factor for hypocalcemia, indicating that other factors besides parathyroid injury, ischemia, or removal are involved in the pathogenesis of postthyroidectomy hypocalcemia. An elevated free thyroxine level, substernal thyroid disease, and carcinoma are risk factors for postthyroidectomy hypocalcemia, and their presence should warrant routine postoperative calcium measurement. In the absence of these risk factors, routine postoperative measurement of serum calcium is unnecessary.

Rapid and accurate detection of a virus in a population is a critical factor in the eventual treatment and/or control of the virus. In this study, we examined use of the polymerase chain reaction (PCR) to detect swine influenza virus in nasal swab specimens from infected pigs. This approach was first standardized, using viral RNA purified by guanidinium/phenol-chloroform extraction and placed in the same transport medium as the swabs. By using highly conserved primers for the swine H1 hemagglutinin, we amplified a 591-base pair fragment that was analyzed by use of agarose gel electrophoresis, Southern blot, and DNA sequencing. To evaluate PCR as a potential diagnostic tool for detection of swine influenza virus infection, we obtained nasal swab specimens from experimentally infected pigs. Amplification by PCR and reamplification of extracted samples with internal primers yielded detectable bands for an amount of virus less than that required to infect embryonating chicken eggs. We also tested swab specimens from pigs involved in 3 separate, natural episodes of swine influenza. These swab specimens were extracted, amplified and reamplified, producing visible bands on the gel and in Southern blots. We performed Southern blot analyses on all PCR products, to confirm that they were from viral H1 RNA. We also cloned and sequenced a 591-base pair product from 1 specimen and found that it was 100% identical to the hemagglutinin gene sequence of A/Sw/Ind/1726/88. Results indicate that PCR can be used to detect swine influenza virus, even in nasal swab specimens, the specimen typically collected for diagnosis of virus infection.

Pyrimethamine, 25 mg thrice weekly, was evaluated as primary prophylaxis for toxoplasmic encephalitis (TE) in a double-blind, randomized clinical trial in patients with human immunodeficiency virus (HIV) disease, absolute CD4 lymphocyte count of < 200/microL (or prior AIDS-defining opportunistic infection), and the presence of serum IgG to Toxoplasma gondii. Leucovorin was coadministered only for hematologic toxicity. There was a significantly higher death rate among patients receiving pyrimethamine (relative risk [RR], 2.5; 95% confidence interval [CI], 1.3-4.8; P = .006), even after adjusting for factors predictive of survival. The TE event rate was low in both treatment groups (not significant). Only 1 of 218 patients taking trimethoprim-sulfamethoxazole but 7 of 117 taking aerosolized pentamidine for prophylaxis against Pneumocystis carinii pneumonia developed TE (adjusted RR for the trimethoprim-sulfamethoxazole group, 0.16; 95% CI, 0.01-1.79; P = .14). Thus, for HIV-infected patients receiving trimethoprim-sulfamethoxazole, additional prophylaxis for TE appears unnecessary.

Unlabelled: The objective of this study was to investigate risk factors for death from different types of stroke among men screened for the Multiple Risk Factor Intervention Trial (MRFIT). A total of 353,340 men were screened by 20 centers for the MRFIT in 1973 to 1975; vital status has been ascertained over an average of 12 years of follow-up (range: 11 to 13 years). Death certificates were coded using the International Classification of Diseases (ICD), ninth revision. Deaths from stroke were classified as death from subarachnoid hemorrhage (ICD code 430), death from intracranial hemorrhage (ICD codes 431 and 432), death from nonhemorrhagic stroke (ICD codes 433 through 438), and death from any type of stroke (ICD codes 430 through 438)., Results: During an average of approximately 12 years of follow-up, 765 deaths from stroke were identified; 139 of these deaths were attributable to subarachnoid hemorrhage; 227, to intracranial hemorrhage; and 399 were classified as nonhemorrhagic stroke. Blood pressure and cigarette smoking were strongly related to each type of stroke. Systolic blood pressure was a stronger predictor than diastolic blood pressure. With the exception of subarachnoid hemorrhage, death rates from each type of stroke increased with age and were higher for black men. The positive association of age and race with subarachnoid hemorrhage was much weaker than for the other types of stroke and was not significant. Income was inversely associated with risk of death from nonhemorrhagic stroke and was not associated with either subarachnoid or intracranial hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Background: With increased efforts to lower serum cholesterol levels, it is important to quantify associations between serum cholesterol level and causes of death other than coronary heart disease, for which an etiologic relationship has been established., Methods: For an average of 12 years, 350,977 men aged 35 to 57 years who had been screened for the Multiple Risk Factor Intervention Trial were followed up following a single standardized measurement of serum cholesterol level and other coronary heart disease risk factors; 21,499 deaths were identified., Results: A strong, positive, graded relationship was evident between serum cholesterol level measured at initial screening and death from coronary heart disease. This relationship persisted over the 12-year follow-up period. No association was noted between serum cholesterol level and stroke. The absence of an association overall was due to different relationships of serum cholesterol level with intracranial hemorrhage and nonhemorrhagic stroke. For the latter, a positive, graded association with serum cholesterol level was evident. For intracranial hemorrhage, cholesterol levels less than 4.14 mmol/L (less than 160 mg/dL) were associated with a twofold increase in risk. A serum cholesterol level less than 4.14 mmol/L (less than 160 mg/dL) was also associated with a significantly increased risk of death from cancer of the liver and pancreas; digestive diseases, particularly hepatic cirrhosis; suicide; and alcohol dependence syndrome. In addition, significant inverse graded associations were found between serum cholesterol level and cancers of the lung, lymphatic, and hematopoietic systems, and chronic obstructive pulmonary disease. No significant associations were found of serum cholesterol level with death from colon cancer, with accidental deaths, or with homicides. Overall, the inverse association between serum cholesterol level and most cancers weakened with increasing follow-up but did not disappear. The association between cholesterol level and death due to cancer of the lung and liver, chronic obstructive pulmonary disease, cirrhosis, and suicide weakened little over follow-up., Conclusions: The association of serum cholesterol with specific causes of death varies in direction, strength, gradation, and persistence. Further research on the determinants of low serum cholesterol level in populations and long-term follow-up of participants in clinical trials are necessary to assess whether inverse associations with noncardiovascular disease causes of death are consequences of noncardiovascular disease, whether serum cholesterol level and noncardiovascular disease are both consequences of other factors, or whether these associations are causal.

A double-blind, placebo-controlled trial was set up to compare clindamycin and pyrimethamine as prophylaxis for toxoplasmic encephalitis (TE) in HIV-infected patients at risk of the disorder. Interim analysis showed that clindamycin-treated patients were 4.4 (95% confidence interval 1.3-15.2) times more likely to experience an adverse effect that necessitated withdrawal of the study drug than those who received placebo. Diarrhoea and rash were reported in 16 (31%) and 11 (21%), respectively, of 52 patients treated with clindamycin (300 mg twice daily) compared with 2 (6%; p = 0.06) and none (p = 0.01) of the 32 placebo-treated patients. The clindamycin arm of the trial was prematurely terminated, although recruitment to the pyrimethamine arm continues.

To assess the combined influence of blood pressure (BP), serum cholesterol level, and cigarette smoking on death from coronary heart disease (CHD) and to describe how these associations vary with age, data on those factors and on mortality for 316,099 men screened for the Multiple Risk Factor Intervention Trial (MRFIT) were examined. Vital status of participants has been determined after an average follow-up of 12 years; 6327 deaths from CHD have been identified. Strong graded relationships between serum cholesterol levels above 4.65 mmol/L (180 mg/dL), systolic BP above 110 mm Hg, and diastolic BP above 70 mm Hg and mortality due to CHD were evident. Smokers with serum cholesterol and systolic BP levels in the highest quintiles had CHD death rates that were approximately 20 times greater than nonsmoking men with systolic BP and cholesterol levels in the lowest quintile. Systolic and diastolic BP, serum cholesterol level, and cigarettes per day were significant predictors of death due to CHD in all age groups. Systolic BP was a stronger predictor than diastolic BP. These results, together with the findings of clinical trials, offer strong support for intensified preventive efforts in all age groups.

Serum cortisol levels are increased in patients after thermal injury. Lymphocyte function is altered in these patients, which renders them susceptible to infections. Elevated cortisol levels may contribute to this compromised state. In this study, we have demonstrated that cortisol directly affects lymphocyte membrane fluidity as measured by the polarization of fluorescence from the membrane-associated probe diphenylhexatriene in peripheral blood lymphocytes. Membrane fluidity increased in vitro with short- or long-term cortisol exposure. However, membranes of control peripheral blood lymphocytes that were previously exposed to cortisol became resistant to the fluidizing effect of cortisol, which implies membrane adaptation to long-term cortisol exposure. Cortisol effects were similar to those associated with ethanol, a known membrane-fluidizing agent, in peripheral blood lymphocytes and cytotoxic T lymphocytes. Membrane fluidity was compared in peripheral blood lymphocytes from thermally injured patients and peripheral blood lymphocytes from normal (control) subjects. Peripheral blood lymphocyte membrane fluidity increased in major thermal injury. Our data suggest that cortisol affects lymphocyte membrane fluidity in vitro in a manner similar to the membrane fluidity alterations that are observed in vivo after thermal injury. These observations reflect a direct membrane effect of cortisol, which may explain, in part, the cellular dysfunction and immunologic suppression that is observed after thermal injury.

Nifedipine is a calcium channel antagonist known to inhibit smooth muscle contraction and cell-mediated immunity. The clinical and local immune response to nifedipine was investigated in an open trial with 10 female interstitial cystitis patients, whose disease was diagnosed according to the consensus criteria developed in 1987 at a National Institutes of Health workshop. To evaluate the symptoms and clinical response of the patients objectively we scored the symptoms of frequency, urgency, nocturia, dysuria and suprapubic pain on a scale of 0 to 2. Nifedipine was administered as a single daily dose determined by a dose-titration test. Urinary interleukin-2 inhibitor activity, a marker of cell-mediated inflammation, was measured using a murine interleukin-2 dependent cell line. Before nifedipine therapy the symptom scores (total of the 5 symptoms) ranged between 5 and 9, and after 2 months they ranged between 0 and 6. Of the 9 patients followed for at least 4 months only 1 failed to have a significant clinical improvement, 5 showed at least a 50% decrease in symptom scores and 3 were asymptomatic. Drug side effects were minimal. Urinary interleukin-2 inhibitor activity before nifedipine therapy confirmed the presence of cell-mediated inflammation. After 4 months of therapy interleukin-2 inhibitor activity was normal in 7 of 9 patients regardless of the severity of symptoms, which indicated that nifedipine exerted an immunosuppressive effect. Although our data suggest that nifedipine is an efficacious, well tolerated, convenient oral medication for the treatment of interstitial cystitis, the true value of nifedipine for patients with this disease must be determined by a prospective, randomized trial of nifedipine versus placebo.

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.

Results of the Prism Adaptation Study (PAS) indicate that prism adaptation improves the success rate of strabismus surgery for patients with acquired esotropia. Patients who show a fusion response to the prisms benefit most from this preoperative treatment. This study analyzes the characteristics of those patients who were and were not prism responders in the PAS. Significant factors predicting a prism response included: patients who were older at the time of onset of their esodeviation (P = .007), duration of deviation less than 1 year (P = .04), alternating fixation (P = .003), fusion on the Worth four-dot test at near with prism neutralization (P = .008), and equal vision (P = .009). Demographic characteristics were similar for both responders and nonresponders except that non-Hispanic patients were significantly more likely to respond to prisms than Hispanic patients (P less than .002). No test or characteristic was found which could reliably predict the prism response. Therefore, all patients with acquired esodeviations should be considered candidates for prism adaptation prior to strabismus surgery.

We observed a human urine-derived protein complex (IL-2-IN) which competitively inhibits interleukin-2 (IL-2) dependent murine lymphocyte proliferation. Measurements of urinary IL-2-IN have been used to stratify the immune response of patients to bacteria in the bladder. Partial characterization of IL-2-IN indicates that it is a heat-stable, 75 kDa complex comprised of interleukin-2 bound to another protein(s). Although the IL-2-IN complex is stable in physiologic buffers, the complex can be disrupted using acidic or low-ionic strength buffers, thereby liberating IL-2. IL-2-IN activity is susceptible to bacterial and endogenous urinary proteolysis. The IL-2 bound in the IL-2-IN complex cannot be detected using a double monoclonal antibody radioimmunoassay for IL-2. Unlike other IL-2 binding proteins, the IL-2 binding protein of the IL-2-IN complex is not a soluble interleukin-2 receptor. A modification of the bioassay for interleukin-2 activity is the method of choice for the detection and quantification of urinary IL-2-IN.

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.

In contrast to the rapid inhibition of bacterial cytidine deaminase by 3,4,5,6-tetrahydrouridine, the onset of inhibition of the enzyme from human liver was found to be relatively slow. Inhibition was found to be reversible, and the corrected rate constants for binding (kon = 2.4 x 10(4) M-1 sec-1) and release (koff = 5.6 x 10(-4) sec-1) were in reasonable agreement with a Ki value (2.9 x 10(-8) M) measured separately under steady-state conditions, which was several orders of magnitude lower than estimates previously reported in the literature. Rates of binding and release of this potential transition state analogue were not appreciably affected by the substitution of deuterium oxide for solvent water. The slow onset of inhibition, which was also observed for cytidine deaminase from HeLa cells, suggests that structural reorganization precedes the formation of a stable enzyme-inhibitor complex. 6-Azacytidine, which favors a "high-anti" configuration at the glycosidic bond, was found to be active as a substrate for cytidine deaminase, with a turnover number exceeding that of cytidine. 2,2'-Anhydro-1-beta-D-arabinofuranosylcytosine, which is restricted to the "syn" configuration, was found to be without activity as a substrate or an inhibitor.

Vertebrate genomes contain an extensive family of genes possessing varying degrees of homology to the v-src oncogene. Most src-related proteins identified to date are intracellular and membrane-associated, although some are transmembrane proteins and function as receptors for peptide growth factors. Three Drosophila gene sequences related to the v-src gene have been identified, each exhibiting a high degree of homology to one or more of the src-family members encoding an intracellular protein. We have isolated a panel of cloned Drosophila sequences exhibiting weak v-src hybridization and were interested to determine whether any members of this group represented homologues of additional known src-family genes, especially those functioning as growth factor receptors. As we report here, four of these clones, representing overlapping portions of the same genomic segment, hybridized preferentially with the v-erb-B oncogene and were further characterized. The deduced amino-acid sequence from a portion of this Drosophila genomic segment is 77% homologous to the kinase domain of human epidermal growth factor (EGF) receptor, a substantially greater degree of homology than was observed with any other known src-family member. By hybridization with a human EGF receptor complementary DNA clone probe, we demonstrate that the same genomic segment showing homology with the kinase domain also contains sequences related to the extracellular domain of the EGF receptor gene.

Several prospective studies have demonstrated an association between low serum cholesterol level and subsequent mortality from cancer. This finding was explored in the large cohort (361,662) of men aged 35 to 57 years who were screened for possible randomization to the Multiple Risk Factor Intervention Trial. Mortality follow-up revealed a significant excess of cancer in the lowest decile of serum cholesterol level during the early years of follow-up, which attenuated over time. In contrast, the association between high serum cholesterol and coronary heart disease did not diminish during the average of seven years of follow-up. These findings are consistent with the inference that the association between low serum cholesterol level and cancer is at least in part due to an effect of preclinical cancer on serum cholesterol level. A subset of the cohort (12,866 men) participated in the randomized Multiple Risk Factor Intervention Trial protocol, which called for annual measurements of serum cholesterol level. Among the 150 of these men who died of cancer during the trial, cholesterol level fell 22.7 mg/dL (0.59 mmol/L) more than in the survivors over an equivalent period. These data are consistent with the foregoing inference.

The Multiple Risk Factor Intervention Trial screening program provided an opportunity (1) to study the association of diastolic blood pressure level, serum cholesterol concentration, and cigarettes per day with all-cause and cause-specific mortality after 5 years among 23,490 black males and (2) to compare these associations with those observed among 325,384 white males. The relationship of serum cholesterol concentration and reported cigarettes per day to all-cause, coronary heart disease (CHD), and cerebrovascular disease mortality was similar for black and white males. Diastolic blood pressure was more positively associated with cerebrovascular disease death among black males than white males (p = 0.047) according to logistic regression analysis. The lower CHD mortality among black males compared to white males was most apparent among hypertensive males (diastolic blood pressure greater than or equal to 90 mm Hg). The relative risk (black vs white) of CHD death adjusted for age, serum cholesterol concentration, and cigarettes per day was 0.69 for hypertensive males compared to 1.15 for nonhypertensive males (p = 0.012 for difference in relative risk estimates). These findings suggest that the causes of CHD and cerebrovascular disease may be different for black and white males, particularly in regard to how these disease processes relate to blood pressure.

We examined the relation between the serum total cholesterol level and the risk of death from stroke during six years of follow-up in 350,977 men, 35 to 57 years of age, who had no history of heart attack and were not currently being treated for diabetes mellitus. The diagnosis of stroke and the type of stroke were obtained from death certificates. Using proportional-hazards regression to control for age, cigarette smoking, diastolic blood pressure, and race or ethnic group, we found that the six-year risk of death from intracranial hemorrhage (International Classification of Diseases, ninth edition [ICD-9], categories 431 and 432) was three times higher in men with serum cholesterol levels under 4.14 mmol per liter (160 mg per deciliter) than in those with higher cholesterol levels (P = 0.05 by omnibus test across five cholesterol levels). On the other hand, a positive association was observed between the serum cholesterol level and death from nonhemorrhagic stroke (P = 0.007). The inverse association of the serum cholesterol level with the risk of death from intracranial hemorrhage was confined to men with diastolic blood pressure greater than or equal to 90 mm Hg, in whom death from intracranial hemorrhage is relatively common. We conclude that there is an inverse relation between the serum cholesterol level and the risk of death from hemorrhagic stroke in middle-aged American men, but that its public health impact is overwhelmed by the positive association of higher serum cholesterol levels with death from nonhemorrhagic stroke and total cardiovascular disease (ICD-9 categories 390 through 459).

The 356,222 men aged 35 to 57 years, who were free of a history of hospitalization for myocardial infarction, screened by the Multiple Risk Factor Intervention Trial (MRFIT) in its recruitment effort, constitute the largest cohort with standardized serum cholesterol measurements and long-term mortality follow-up. For each five-year age group, the relationship between serum cholesterol and coronary heart disease (CHD) death rate was continuous, graded, and strong. For the entire group aged 35 to 57 years at entry, the age-adjusted risks of CHD death in cholesterol quintiles 2 through 5 (182 to 202, 203 to 220, 221 to 244, and greater than or equal to 245 mg/dL [4.71 to 5.22, 5.25 to 5.69, 5.72 to 6.31, and greater than or equal to 6.34 mmol/L]) relative to the lowest quintile were 1.29, 1.73, 2.21, and 3.42. Of all CHD deaths, 46% were estimated to be excess deaths attributable to serum cholesterol levels 180 mg/dL or greater (greater than or equal to 4.65 mmol/L), with almost half the excess deaths in serum cholesterol quintiles 2 through 4. The pattern of a continuous, graded, strong relationship between serum cholesterol and six-year age-adjusted CHD death rate prevailed for nonhypertensive nonsmokers, nonhypertensive smokers, hypertensive nonsmokers, and hypertensive smokers. These data of high precision show that the relationship between serum cholesterol and CHD is not a threshold one, with increased risk confined to the two highest quintiles, but rather is a continuously graded one that powerfully affects risk for the great majority of middle-aged American men.

The potential determinants of the changes in chronic obstructive pulmonary disease (COPD) mortality were evaluated using both the Multiple Risk Factor Intervention Trial (MRFIT) screenees, the longitudinal analysis of the participants, and the differences in special intervention (SI) and usual care (UC) groups. COPD was the underlying cause for only one third of all death certificates listing COPD. Small changes in classification will have a major impact on reported COPD death rates. Cigarette smoking is clearly the primary determinant of COPD mortality. Decreased pulmonary function is an independent risk factor for coronary heart disease (CHD) mortality. Smoking cessation results in a slower rate of decline in pulmonary function over time, especially among heavy smokers. Careful evaluation of smoking cessation, including repeat chemical measures, suggest that the percentage of long-term quitters, especially among heavy smokers has been overestimated. The low percentage of quitters substantially reduced the power to detect an intervention effect. The increased cigarette smoking among recent older cohorts, and failure to substantially reduce smoking, especially among heavy smokers, may be an important factor accounting for the failure to note a decline in COPD mortality among older persons.

To assess the impact of serum cholesterol level on the risk of fatal coronary heart disease for men with high blood pressure, the six-year follow-up data from 361,662 men (aged 35 to 57 years) screened in 18 cities in the recruitment effort for the Multiple Risk Factor Intervention Trial were evaluated. Of these men, 356,222 reported no history of hospitalization for myocardial infarction; 100,032 of these 356,222 had a baseline mean diastolic blood pressure equal to or greater than 90 mm Hg. For those men with high blood pressure, the overall age-adjusted six-year rate of coronary heart disease death was 79 percent higher than for those with diastolic blood pressure less than 90 mm Hg. Compared with men with diastolic blood pressure less than 90 mm Hg and serum cholesterol below 182 mg/dl, men with diastolic blood pressure equal to or greater than 90 mm Hg had the following relative risks, based on the serum cholesterol level: for those with a serum cholesterol level less than 182 mg/dl, risk was 1.64; for those with a level of 182 to 202 mg/dl, risk was 2.14; for those with a level of 203 to 220 mg/dl, risk was 3.14; for those with a level of 221 to 244 mg/dl, risk was 3.29; and for those with a level equal to or greater than 245 mg/dl, risk was 5.14. Thus, for men with high blood pressure, serum cholesterol related to coronary heart disease risk in a strong, graded way, over the entire distribution of serum cholesterol, from levels of 182 mg/dl and higher. This was the case for hypertensive male smokers and nonsmokers, with cigarette use associated with a further marked increase in risk--at least a doubling of the mortality rate--at any level of serum cholesterol. These data underscore the necessity for a strategy of comprehensive care for persons with high blood pressure, including approaches to both nutritional and hygienic counseling and drug treatment, aimed at controlling all of the established major risk factors influencing prognosis.

The Drosophila genome contains three major sequences related to the v-src gene. Previously published molecular studies have confirmed the structural homology between v-src and two of the Drosophila sequences. We have sequenced a portion of the third v-src-related Drosophila gene and found that it also shares structural homology with vertebrate and Drosophila src-family genes. RNA sequences from each of the src genes are present in pre-blastoderm embryos indicating that they are of maternal origin. As embryogenesis proceeds, the levels of each of the src RNA sequences decline. The pre-blastoderm src gene transcripts contain poly(A) and are present on polyribosomes suggesting that they are functional mRNAs. Since the Drosophila src transcripts were maternally inherited, we also investigated their distribution in adult females. The majority of the src transcripts in adult females were contained in ovaries. Only low levels of the transcripts were detected in males. These results strongly suggest that an abundant supply of src protein is required during early embryogenesis, perhaps at the time of cellularization of the blastoderm nuclei.

Adenosine deaminase from calf intestine hydrolyzes adenine at a limiting rate four orders of magnitude lower than that for adenosine, while Km values for these substrates are about the same (Wolfenden, R., et al. (1969), Biochemistry 8, 2412-2415). Reactivity of 6-substituents, toward nucleophilic displacement, is found to be affected only slightly by removal of ribose as a 9-substituent, in model reactions. Substituent ribose thus appears to stabilize, selectively, the transition state for enzymatic deamination. In contrast with the small influence of substituent ribose on the apparent binding affinity of substrates, removal of substituent ribose from a potential transition state analogue, 1,6-dihydro-6-hydroxy-methylpurine ribonucleoside, results in a lowering of its affinity for the enzyme by several orders of magnitude. The synthesis of the analogue and related compounds is described, and their properties compared with those of other photoadducts and of the naturally occurring inhibitors covidarabine and coformycin. Binding of these inhibitors is found to result in the appearance of ultraviolet-absorbing bands in the neighborhood of 323 nm.

The risks associated with various levels of serum cholesterol were determined by analysis of 6-year mortality in 361,662 men aged 35-57. Above the 20th percentile for serum cholesterol (greater than 181 mg/dl, greater than 4.68 mmol/l), coronary heart disease (CHD) mortality increased progressively; the relative risk was large (3.8) in the men with cholesterol levels above the 85th percentile (greater than 253 mg/dl, greater than 6.54 mmol/l). When men below the 20th cholesterol percentile were used as the baseline risk group, half of all CHD deaths were associated with raised serum cholesterol concentrations; half of these excess deaths were in men with cholesterol levels above the 85th percentile. For both CHD and total mortality, serum cholesterol was similar to diastolic blood pressure in the shape of the risk curve and in the size of the high-risk group. This new evidence supports the policy of a moderate fat intake for the general population and intensive treatment for those at high risk. There is a striking analogy between serum cholesterol and blood pressure in the epidemiological basis for identifying a large segment of the population (10-15%) for intensive treatment.