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Context: Overweight and obesity are increasing in the United States. Changes in diet and physical activity are important for weight control.Objectives: To examine the prevalence of attempting to lose or to maintain weight and to describe weight control strategies among US adults.Design: The Behavioral Risk Factor Surveillance System, a random-digit telephone survey conducted in 1996 by state health departments. Setting The 49 states (and the District of Columbia) that participated in the survey.Participants: Adults aged 18 years and older (N = 107 804).Main Outcome Measures: Reported current weights and goal weights, prevalence of weight loss or maintenance attempts, and strategies used to control weight (eating fewer calories, eating less fat, or using physical activity) by population subgroup.Results: The prevalence of attempting to lose and maintain weight was 28.8% and 35.1 % among men and 43.6% and 34.4% among women, respectively. Among those attempting to lose weight, a common strategy was to consume less fat but not fewer calories (34.9% of men and 40.0% of women); only 21.5% of men and 19.4% of women reported using the recommended combination of eating fewer calories and engaging in at least 150 minutes of leisure-time physical activity per week. Among men trying to lose weight, the median weight was 90.4 kg with a goal weight of 81.4 kg. Among women, the median weight was 70.3 kg with a goal weight of 59.0 kg.Conclusions: Weight loss and weight maintenance are common concerns for US men and women. Most persons trying to lose weight are not using the recommended combination of reducing calorie intake and engaging in leisure-time physical activity 150 minutes or more per week. [ABSTRACT FROM AUTHOR]

Information about dietary behaviors, attitudes, and knowledge is important for state and local health agencies because national monitoring lacks the local representativeness and timeliness necessary to catalyze community interest and to design, target, and evaluate dietary intervention programs. Currently, however, both methods and resources are limited for surveying diet in the population of a state or community. Brief assessments are included in the Youth Risk Behavior Surveillance System for adolescents, which is conducted by state departments of education, and in the Behavioral Risk Factor Surveillance System for adults, which is operated by state departments of health. More quantitatively precise measurements are being made by a few states and communities but personnel and financial resources for such surveys are limited. Nutritionists in state and local health agencies should explore the possibility of developing public-private partnerships with food producers, retailers, and marketers to collect information about dietary determinants and behaviors in states and communities. Better standardization of dietary assessment methods is needed, as is development of better methods to identify attitudes about diet and barriers to dietary improvement. Most important, though, dietary surveillance in states and communities must be more strongly tied to intervention programs intended to improve nutrition in those populations. (C) 1997 American Society for Clinical Nutrition [ABSTRACT FROM AUTHOR]

Background: Modulating the epigenome has long been considered a potential opportunity for therapeutic intervention in numerous disease areas with several approved therapies marketed, primarily for cancer. Despite the overall promise of early approaches, however, these drugs have been plagued by poor pharmacokinetic and safety/tolerability profiles due in large part to off-target effects and a lack of specificity., Results: Recently, there has been marked progress in the field on a new generation of epigenomic therapies which address these challenges directly by targeting defined loci with highly precise, durable, and tunable approaches. Here, we review the promise and pitfalls of epigenetic drug development to date and provide an outlook on recent advances and their promise for future therapeutic applications., Conclusions: Novel therapeutic modalities leveraging epigenetics and epigenomics with increased precision are well positioned to advance the field and treat patients across disease areas in the coming years., (© 2023. The Author(s).)

Umbilical cord blood (UCB) is a valuable source of hematopoietic stem cells (HSCs) for use in allogeneic transplantation. Key advantages of UCB are rapid availability and less stringent requirements for HLA matching. However, UCB contains an inherently limited HSC count, which is associated with delayed time to engraftment, high graft failure rates, and early mortality. 16,16-Dimethyl prostaglandin E2 (dmPGE2) was previously identified to be a critical regulator of HSC homeostasis, and we hypothesized that brief ex vivo modulation with dmPGE2 could improve patient outcomes by increasing the "effective dose" of HSCs. Molecular profiling approaches were used to determine the optimal ex vivo modulation conditions (temperature, time, concentration, and media) for use in the clinical setting. A phase 1 trial was performed to evaluate the safety and therapeutic potential of ex vivo modulation of a single UCB unit using dmPGE2 before reduced-intensity, double UCB transplantation. Results from this study demonstrated clear safety with durable, multilineage engraftment of dmPGE2-treated UCB units. We observed encouraging trends in efficacy, with accelerated neutrophil recovery (17.5 vs 21 days, P = .045), coupled with preferential, long-term engraftment of the dmPGE2-treated UCB unit in 10 of 12 treated participants.

With sequence analysis of the human genome well underway, there is an increasingly urgent challenge to understand the fundamental function and interplay of genes that build and maintain an organism. Several approaches will be critical for interpreting gene function, including random cDNA sequencing, expression profiling in different tissues, genetic analysis of human or model organism phenotypes, and creation of transgenic or "knockout" animals. Traditional gene-trapping approaches, in which genes are randomly disrupted with DNA elements inserted throughout the genome, have been used to generate large numbers of mutant organisms for genetic analysis. Recent modifications of gene-trapping methods and their increased use in mammalian systems are likely to result in a wealth of new information on gene function. Various trapping strategies allow genes to be segregated based on criteria like the specific subcellular location of an encoded protein, the tissue expression profile, or responsiveness to specific stimuli. Genome-wide gene-trapping strategies, which integrate gene discovery and expression profiling, can be applied in a massively parallel format to produce living assays for drug discovery.

As recently as 1990, there was no reservation-wide, population-based health status information about Navajo Indians. To remedy this shortcoming, the Navajo Health and Nutrition Survey was conducted from 1991 to 1992 to assess the health and nutritional status of Navajo Reservation residents using a population-based sample. Using a three-stage design, a representative sample of reservation households was selected for inclusion. All members of selected households 12 y of age and older were invited to participate. A total of 985 people in 459 households participated in the study. Survey protocols were modeled on those of previous national surveys and included a standard blood chemistry profile, complete blood count, oral glucose tolerance test, blood pressure, anthropometric measurements, a single 24-h dietary recall and a questionnaire on health behaviors. The findings from this survey, reported in the accompanying papers, inform efforts to prevent and control chronic disease among the Navajo. Lessons learned from this survey may be of interest to those conducting similar surveys in other American Indian and Alaska Native populations.

Noninsulin-dependent diabetes mellitus is a major health problem among most American Indian tribes. This is the first population-based reservation-wide study of the Navajo that has used oral glucose tolerance testing to determine diabetes status. Employing WHO criteria, we found an age-standardized prevalence of diabetes mellitus (DM) of 22.9% among persons aged 20 y and older. This prevalence is 40% higher than any previous age-standardized estimate for the Navajo and four times higher than the age-standardized U.S. estimate. More than 40% of Navajo aged 45 y and older had DM. About one third of those with DM were unaware of it, with men more likely to be unaware than women. Among persons with a medical history of DM, almost 40% had fasting plasma glucose values > or = 200 mg/dL. Persons with DM were heavier, more sedentary and more likely to have a family history of DM than were persons without DM. Persons with DM had more hypertension, lower HDL levels and higher triglyceride levels than their counterparts without DM. Insulin usage was infrequent among persons with a history of DM, and about one third of women with such a history used no medical therapy to control their diabetes. Although important measures to combat diabetes have already been undertaken by the Navajo, additional efforts are required to slow the progression of this disease and prevent its sequelae.

Coronary heart disease was uncommon among the Navajo in the past, but appears to have increased substantially over the last few decades. The 1991-1992 Navajo Health and Nutrition Survey, which included interviews and examinations of 303 men and 485 women between the ages of 20 and 91 y, is the first population-based examination of coronary heart disease risk factors in this tribe. Coronary heart disease risk characteristics were common, particularly overweight (men, 35%; women, 62%), hypertension (men, 23%; women, 14%) and diabetes mellitus (men, 17%; women, 25%). Among 20- to 39-y-olds, a large proportion of men reported that they currently smoked cigarettes (23%); use of chewing tobacco or snuff was also prevalent among these 20- to 39-y-old men (37%) and women (31%). Although serum concentrations of total cholesterol were fairly comparable to those seen in the general U.S. population, fasting serum triglyceride concentrations were high (median: men, 132 mg/dL; women, 137 mg/dL), and concentrations of HDL cholesterol were low, particularly among women (median: men, 42 mg/dL; women, 44 mg/dL). Body mass index was associated with levels of most risk factors, and, independently of the level of overweight, a truncal pattern of body fat was related to adverse lipid levels among men. A large proportion of men (20%) and women (30%) reported not having participated in physical activity during the preceding month. Lessons learned from past intervention activities among the Navajo, particularly those for diabetes, may be useful in managing these risk factors to reduce the future burden of coronary heart disease.

Cancer-screening behaviors, reproductive history, risk behaviors during pregnancy and chronic disease risk factors were examined in a representative sample of 566 Navajo women residing on the Navajo Reservation in 1991-1992. Among all women 15 y and older, 59% were overweight, 4% were current smokers, 10% currently used smokeless tobacco and 12% were anemic. Seventy-one percent of Navajo women aged 18 and older reported ever having had a Pap smear, but only 35% of women aged 50 and over reported ever having had a mammogram. Among parous women, the prevalence of having received no prenatal care for any pregnancy declined from 60% among women 60 and older to 13% among women 20-29 y of age, and the prevalence of ever having had a child born at home declined from 82 to 2%. These data suggest marked secular improvement in these pregnancy-related risk behaviors. However, data on cancer-screening behaviors indicate opportunities to improve health of Navajo women by increasing their use of mammography and Pap smear screening services.

Historically, the Navajo exhibited a low prevalence of overweight, but a number of small studies over the past few decades indicate that the prevalence is increasing. In the population-based Navajo Health and Nutrition Survey conducted in 1991-92, overweight was defined as a body mass index (BMI, kg/m2) at or above the 85th percentile (BMI > 27.8 for men, > 27.3 for women) of the Second National Health and Nutrition Examination Survey. One third of men age 20 and 39 and one half of men age 40 and 59, but fewer than 10% of men age 60 and older were overweight. Two thirds or more of women in all age groups were overweight. Nineteen percent of the participants underestimated their weight status (underweight, appropriate, overweight) relative to their BMI category and 17% overestimated their weight status. Women overestimated their weight status more often than men (P < 0.05), and participants age 20-39 overestimated their weight status more often than older participants (P < 0.001). Men and women age 60 and older preferred heavier body shape models as ideals of health more often than younger participants (P < 0.001). Nearly half of the participants, regardless of their weight status, reported that they were trying to lose weight; most reported using diet and exercise. Because overweight is an important risk factor for many chronic diseases, including diabetes mellitus, cardiovascular disease and cancer, primary prevention of overweight and weight management for adults are recommended to prevent an increase in the burden of chronic disease among the Navajo.

Diet has been implicated in the etiology of chronic diseases in many populations, including the Navajo and other American Indian tribes. This report describes the current nutrient intake of the Navajo and identifies the primary food sources of key nutrients. In the Navajo Health and Nutrition Survey, interviewers obtained single 24-h diet recalls from 946 nonpregnant participants age 12-91 between October 1991 and December 1992. Among various sex and age groups, total fat contributed 33-35% of energy and saturated fat contributed 10-11% of energy in the diets. Median fiber intake was 11-14 g/d. Median intakes of vitamin A, vitamin E, vitamin B-6, folate, calcium and magnesium were below sex- and age-specific recommended dietary allowances (RDA) for men and women of all age groups. Intake of vitamin C was below the RDA for men and women age 20 and older. Median iron intake was below the RDA for women under age 60. Fruits and vegetables were each consumed less than once per day per person, as were dairy products. Fry bread and Navajo tortillas, home-fried potatoes, mutton, bacon and sausage, soft drinks, coffee and tea provided 41% of the energy and 15-46% of the macronutrients consumed. Recommendations to increase the intake of essential micronutrients in the Navajo diet are presented.

Background: Although diet is implicated in the elevated rate of cardiovascular disease among some American Indian tribes, the dietary intakes of these individuals have not been described. The Strong Heart Dietary Study compared diets of 10 tribes in Arizona, Oklahoma, and the Dakotas to examine the possible contribution of diet to cardiovascular and other chronic diseases., Methods: During 1988-1991, 892 people responded to a 24 hr diet recall questionnaire. Nutrient intake by study area, sex, and age group were compared by analysis of variance, and intakes were compared with nutrient intakes reported by participants in Phase 1 of the Third National Health and Nutrition Examination Survey and with dietary recommendations of the National Research Council, the American Heart Association, and the Healthy People 2000 objectives., Results: The intake of energy and nutrients varied significantly by sex and age. Men consumed more energy, macronutrients, and sodium than did women (P < or = 0.001). Women's diets were denser in carbohydrate, beta-carotene, vitamin C, and vitamin E than were men's diets (P < or = 0.001). Younger participants consumed more energy, macronutrients, vitamin E, and sodium than did older participants (P < or = 0.001). Older participants had diets denser in protein and beta-carotene than did younger participants (P < or = 0.001). Energy intake did not differ significantly by study area, but men in Arizona consumed more energy from carbohydrate and less energy from total fat than did men elsewhere (P < or = 0.01). Men and women in Arizona consumed more cholesterol and fiber than did other participants (P < or = 0.01) and less of the antioxidant vitamins (P < or = 0.01). Participants in the Strong Heart Diet Study reported diets higher in fats and cholesterol than did participants in Phase 1 of the Third National Health and Nutrition Examination Survey. Few Strong Heart participants achieved dietary recommendations for the reduction of risk of chronic disease., Conclusions: Area differences in nutrient intake were observed, but most participants consumed diets associated with increased risk of heart disease and other chronic diseases. Women and older participants in general reported healthier nutrient intakes. Dietary intervention programs should educate American Indians about dietary modifications to reduce the risk of cardiovascular and other nutrition-related disorders.

Tornado preparedness warning system effectiveness, and shelter-seeking behavior were examined in two Alabama areas after tornado warnings. In the area without sirens, only 28.9% of 194 respondents heard a tornado warning of these, 73.2% first received the warning from radios or television. In the area with sirens, 88.1% of 193 respondents heard a warning, and 61.8% first received the warning from a siren. Knowledge of warnings, access to shelter, and education were key predictors for seeking shelter. Our findings indicate that installing sirens, providing access to shelter, and teaching appropriate responses to warnings are important elements of an effective disaster prevention system.

A 1-stage, random-digit dial telephone survey was conducted to obtain information on characteristics of pet populations and pet-owning households in 1988 in Marion and Tippecanoe Counties, Indiana. Interviews for 653 out of 731 eligible households were completed (response rate, 88%). Approximately half of the households in each county owned a pet. Of these, 35% owned at least 1 dog, and 23% owned at least 1 cat. Households with pets were more likely to be larger and have a higher median income score than were households without pets. Households with children between 6 and 17 years old were more likely to own pets than were households with no children; however, no difference in pet ownership proportions was determined for households with children < or = 5 years old, compared with households without children. For dogs, younger dogs and male dogs were less likely to have been neutered than older dogs and female dogs. Older cats were more likely to have been neutered than younger cats, with neutering percentages of > 90% for cats in the oldest age group. Approximately 20% of dogs and 40% of cats had not been seen by a veterinarian in the 12 months preceding the interview.

Using a 1-stage random-digit dial telephone survey, we estimated the number of pet dogs and cats and cancer case ascertainment in the principal catchment area of an animal tumor registry in Indiana, the Purdue Comparative Oncology Program (PCOP). These findings will assist in the estimation of pet cancer incidence rates for the PCOP. The estimated canine and feline populations for Marion County were 144,039 (95% confidence interval, 121,555 to 166,523) and 94,998 (74,384 to 115,648), respectively. For Tippecanoe County (excluding university housing residences), the estimated canine population was 18,000 (14,445 to 21,555), whereas the estimated feline population was 17,165 (12,569 to 21,761). The estimated cancer case ascertainment was 88.3% (dogs, 92.5%; cats, 83.0%) with no statistically significant difference in the estimated ascertainment by county of residence or by species of pet. The amount that owners report themselves willing to pay for treatment of cancer in dogs or cats, however, differed in counties polled. This method's appropriateness for estimating pet populations in general and the validity of the data gathered were supported by response rate of 88.0% and by concurrence with census data for household characteristics previously documented to be associated with pet dog and cat ownership.

The initial stages in the biosynthesis of the cloned Na+/glucose cotransporter were examined by in vitro expression of the protein in the absence and presence of pancreatic microsomes. Glycosylation was detected by endoglycosidase-H shifts in the apparent size of the proteins on SDS-PAGE. In the presence of microsomes, Mr increased from 52,000 to 58,000, and this was reversed by endo-H. This demonstrates that the protein is glycosylated and that there is no large cleavable signal sequence. Using partial transcripts and site-directed mutagenesis, we established that Asn-248 is glycosylated. Glycosylation was not required for the functional expression of the transporter in Xenopus oocytes. In terms of the topology of the protein, these results suggest that Asn-248 is on the external surface of the membrane.

Medicare records represent a potential resource for surveillance data on hospitalizations among the elderly. Several features make these data useful for describing hospitalization patterns: a) Medicare covers hospitalization expenses for approximately 95% of the U.S. population greater than or equal to 65 years, and these data are considered to represent accurately the hospitalization patterns of this group; b) The comprehensive nature of the information about the beneficiary population provides public health researchers with data to generate accurate rates for well-defined demographic and geographic subgroups; c) Because data for all covered hospitalizations have been included in the file since 1984, stable estimates for even relatively rare conditions can be generated for any years since then; d) A unique personal identifier on each record permits the differentiation of first from subsequent hospitalizations, thereby permitting public health researchers to generate both counts and rates of hospitalizations by person and by event; and e) Temporal trends in hospitalization can be generated for 1980 through 1988, because data are available in machine-readable form. This report presents surveillance data for elderly persons hospitalized in 1988 for several diseases of public health importance. In 1988, approximately 9.1 million hospitalizations covered by Medicare occurred among persons greater than or equal to 65 years. For major disease categories, the rates of persons discharged ranged from 7,448/100,000 for circulatory diseases to 274/100,000 for blood diseases. For the 49 discrete diseases and conditions studied, rates varied widely by gender, race, and age. Conditions also varied widely in the mean number of discharges per person and in the probability that the condition would be recorded as the principal diagnosis.

The binding and conformational properties of the divalent cation site required for H+,K(+)-ATPase catalysis have been explored by using Ca2+ as a substitute for Mg2+. 45Ca2+ binding was measured with either a filtration assay or by passage over Dowex cation exchange columns on ice. In the absence of ATP, Ca2+ was bound in a saturating fashion with a stoichiometry of 0.9 mol of Ca2+ per active site and an apparent Kd for free Ca2+ of 332 +/- 39 microM. At ATP concentrations sufficient for maximal phosphorylation (10 microM), 1.2 mol of Ca2+ was bound per active site with an apparent Kd for free Ca2+ of 110 +/- 22 microM. At ATP concentrations greater than or equal to 100 microM, 2.2 mol of Ca2+ were bound per active site, suggesting that an additional mole of Ca2+ bound in association with low affinity nucleotide binding. At concentrations sufficient for maximal phosphorylation by ATP (less than or equal to 10 microM), APD, ADP + Pi, beta,gamma-methylene-ATP, CTP, and GTP were unable to substitute for ATP. Active site ligands such as acetyl phosphate, phosphate, and p-nitrophenyl phosphate were also ineffective at increasing the Ca2+ affinity. However, vanadate, a transition state analog of the phosphoenzyme, gave a binding capacity of 1.0 mol/active site and the apparent Kd for free Ca2+ was less than or equal to 18 microM. Mg2+ displaced bound Ca2+ in the absence and presence of ATP but Ca2+ was bound about 10-20 times more tightly than Mg2+. The free Mg2+ affinity, like Ca2+, increased in the presence of ATP. Monovalent cations had no effect on Ca2+ binding in the absence of ATP but dit reduce Ca2+ binding in the presence of ATP (K+ = Rb+ = NH4 + greater than Na+ greater than Li+ greater than Cs+ greater than TMA+, where TMA is tetramethylammonium chloride) by reducing phosphorylation. These results indicate that the Ca2+ and Mg2+ bound more tightly to the phosphoenzyme conformation. Eosin fluorescence changes showed that both Ca2+ and Mg2+ stabilized E1 conformations (i.e. cytosolic conformations of the monovalent cation site(s)) (Ca.E1 and Mg.E1). Addition of the substrate acetyl phosphate to either Ca.E1 or Mg.E1 produced identical eosin fluorescence showing that Ca2+ and Mg2+ gave similar E2 (extracytosolic) conformations at the eosin (nucleotide) site. In the presence of acetyl phosphate and K+, the conformations with Ca2+ or Mg2+ were also similar. Comparison of the kinetics of the phosphoenzyme and Ca2+ binding showed that Ca2+ bound prior to phosphorylation and dissociated after dephosphorylation.(ABSTRACT TRUNCATED AT 400 WORDS)

Defining the structural and catalytic properties of the ion transport site(s) of enzyme-phosphorylating ATPases is of key importance in understanding the mechanism of ion transport by these enzymes. In the case of the H+, K(+)-ATPase, SCH 28080 (3-(cyanomethyl)-2-methyl-8-(phenylmethoxy)imidazo[1,2a]-pyridine) has been shown to act as a high affinity, extracytosolic, K(+)-competitive inhibitor of Mg2+, K(+)-ATPase activity (Wallmark, B., Briving, C., Fryklund, J., Munson, K., Jackson, R., Mendlein, J., Rabon, E., and Sachs, G. (1987) J. Biol. Chem. 262, 2077-2084). To define the nature of the SCH 28080-binding site in relation to the catalytic cycle of the enzyme, we have investigated the effects of this potential K+ transport site probe on the steady-state and partial reactions of the H+, K(+)-ATPase. In the absence of K+, SCH 28080 inhibits Mg2(+)-ATPase activity with high affinity (apparent Ki = 30 nM). Inhibition is due to K(+)-like prevention of phosphoenzyme formation. SCH 28080 has no effect on Mg2(+)-catalyzed dephosphorylation. SCH 28080, at concentrations less than 0.5 microM, increases the apparent Km for K+ for Mg2+, K(+)-ATPase activity with little effect on the maximum velocity. At higher concentrations of SCH 28080, reversal of inhibition by higher K+ concentrations is not complete, due to inhibition of ATPase activity by high K+. In contrast, SCH 28080 inhibits K(+)-stimulated dephosphorylation by competitively displacing K+ from phosphoenzyme with an extracytosolic conformation of the monovalent cation site (E2P) at low concentrations of SCH 28080 and K+. At higher concentrations, 10 microM SCH 28080 and 50 mM K+, a slowly dephosphorylating complex with both SCH 28080 and K+ bound to E2P may form which represents a small fraction of the total E2P (15-25%). Preincubation of SCH 28080 with E2P completely blocks K(+)-stimulated dephosphorylation, and K+ is unable to reverse this preincubation effect, indicating that the SCH 28080 dissociation rate is at least as slow as K(+)-independent dephosphorylation of E2P. These findings indicate that SCH 28080 inhibits K(+)-stimulated ATPase activity by competing with K+ for binding to E2P and blocking K(+)-stimulated dephosphorylation. In the absence of K+, SCH 28080 has a higher apparent affinity for E2P, but it permits K(+)-independent dephosphorylation. Since the dissociation rate of SCH 28080 from the enzyme is slow, phosphoenzyme formation is prevented by SCH 28080 remaining bound to the extracytosolic conformation of the monovalent cation site, thereby reducing the steady-state level of phosphoenzyme.

H-FLUX is an interactive computer program designated to facilitate the calculation of acid or base efflux from a tissue or organism into the surrounding media. It will accept data derived from different experimental protocols and allows for a high level of experimental flexibility. An example calculation of acid efflux from the marine fish Opsanus beta is given.

Fluorescein isothiocyanate was used to covalently label the gastric (H+ + K+)-ATPase. FITC treatment of the enzyme inhibited the ATPase activity while largely sparing partial reactions such as the associated p-nitrophenylphosphatase activity. ATP protected against inhibition suggesting the ligand binds at or near an ATP binding site. At 100% inhibition the stoichiometry of binding was 1.5 nmol FITC per mg Lowry protein a value corresponding to maximal phosphoenzyme formation. Binding occurred largely to a peptide of 6.2 isoelectric point, although minor labelling of a peptide of pI 5.6 was also noted. Fluorescence was quenched by K+, Rb+ and Tl+ in a dose-dependent manner, and the K0.5 values of 0.28, 0.83 and 0.025 mM correspond rather well to the values required for dephosphorylation at a luminal site. Vanadate, a known inhibitor of the gastric ATPase produced a slow Mg2+-dependent fluorescent quench. Ca2+ reversed the K+-dependent loss of fluorescence and inhibited it when added prior to K+. This may relate to the slow phosphorylation in the presence of ATP found when Ca2+ was substituted for Mg2+ and the absence of K+-dependent dephosphorylation. The results with FITC-modified gastric ATPase provide evidence for a conformational change with K+ binding to the enzyme.

The parietal cell occupies a unique niche among eukaryotic cells in that it develops a proton gradient of more than 4 million-fold across the membrane of the secretory canaliculus. At rest, the cell is still able to develop a proton gradient across intracellular membranes, such that the acid compartment has a pH of less than 4. Acidification depends on the simultaneous presence of ATP, K+ and Cl- as demonstrated in permeabilized cells. With acidification of the luminal side of the proton pump, there is a corresponding alkalinization of the cytosolic face as revealed by carboxyfluorescein fluorescence enhancement. Disposal of the resultant alkali depends on carbonic anhydrase activity and the functioning of a coupled Na+:H+ and Cl-:OH-antiport across the basal lateral membrane. Accordingly, with secretion there is an increased cellular Cl- level, which is exported across the apical membrane in association with K+. The Na+ pump dependent secretion of KCl across this membrane is one of the major sites of the gastric ATPase. Membranes isolated from secreting tissue contain a KCl permeation pathway largely absent from membranes isolated from resting tissue. The pump itself acts as an H+ for K+ exchange ATPase which is most probably composed of at least two peptides of 100 000 Mr. That catalytic cycle consists of formation and breakdown of a covalent aspartyl phosphate. Formation of the intermediate depends on loss of K+ from cytosolic binding sites, and breakdown of the intermediate depends on K+ binding to the luminal face of the enzyme. During breakdown, an acid labile E . P is formed, and, at high ATP concentrations, loss of this form of the enzyme is probably the rate limiting step.

A health survey of 2,039 persons in 606 households located near the Stringfellow Hazardous Waste Disposal site, Riverside County, California, and in a reference community was conducted to assess whether rates of adverse health outcomes were elevated among persons living near the site. Data included a household questionnaire, medical records of reported cancers and pregnancies, and birth and death certificates. The study areas appeared similar with respect to mortality, cancer incidence, and pregnancy outcomes. In contrast, rate ratios were greater than 1.5 for 5 of 19 reported diseases, i.e., ear infections, bronchitis, asthma, angina pectoris, and skin rashes. Prevalence odds ratios for 23 symptoms were uniformly greater than 1.0, and 8 symptoms had odds ratios greater than 1.5: blurred vision, pain in ears, daily cough for more than a month, nausea, frequent diarrhea, unsteady when walking, and frequent urination. The apparent broad-based elevation in reported diseases and symptoms may reflect increased perception or recall of conditions by respondents living near the site. These results indicate that future community-based health studies should include medical and psychosocial assessment instruments sufficient to distinguish between changes in health status and effects of resident reporting tendency.

The mechanism of gastric antisecretory action for trifluoperazine, verapamil and 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) has been studied utilizing isolated hog gastric membranes enriched with (H+ + K+)-ATPase. The drugs inhibited the gastric ATPase due to their apparent competition with K+ for the luminal high-affinity K+-site of the ATPase. The dose to inhibit 50% (ID50) of the ATPase in the membranes rendered freely permeable to K+ (20 mM) was 50 microM for trifluoperazine and 1.5 mM for verapamil and TMB-8. In intact hog gastric membranes which develop a pH gradient in the presence of valinomycin, ATP and KCl, however, trifluoperazine at 4 microM, verapamil and TMB-8 at 15 microM inhibited 40 and 30% of the valinomycin-stimulated ATPase activity, respectively, and also blocked the ionophore-dependent intravesicular acidification as measured by aminopyrine accumulation. The enhanced potency of the drugs to inhibit the ATPase in the intact membrane vesicles may be attributed to the accumulation of the drugs as a weak base within the vesicles, where the luminal K+-site of the ATPase is accessible. Calmodulin and Ca2+ had no effect on the extent of H+-accumulation as measured by aminopyrine accumulation in the membrane vesicles which were prepared in the presence of 1 mM EGTA. Since the drugs showed similar potency in interfering with H+ movements either in the membrane vesicles or isolated rabbit gastric glands stimulated by dibutyryl cAMP, it is reasonable to suggest the inhibitory effect of the drugs on (H+ + K+)-ATPase as a primary cause for such interferences in both cases. A trifluoperazine analog and other lipophilic amine drugs similarly inhibited (H+ + K+)-ATPase and H+ accumulation in the membrane vesicles or in the glands. We have concluded that a tertiary amine, the only common functional group among these drugs, is primarily responsible for their ability to interact with the high-affinity K+ site of the gastric ATPase.

A hydrophobic amine, SCH 28080, 2-methyl-8-(phenylmethoxy)imidazo(1,2a)pyridine-3-acetonitrile, previously shown to inhibit gastric acid secretion in vivo and in vitro, was also shown to inhibit basal and stimulated aminopyrine accumulation in isolated gastric glands when histamine, high K+ concentrations, or dibutyryl cAMP were used as secretagogues. Stimulated, but not basal, oxygen consumption was also inhibited. Neutralization of the acid space of the parietal cell by high concentrations of the weak base, imidazole, reduced the potency of the drug, suggesting that SCH 28080 was active when protonated. Studies on the isolated H+,K+-ATPase showed that the compound inhibited the enzyme competitively with K+, whether ATP or p-nitrophenyl phosphate were used as substrates. In contrast, the inhibition was mixed with respect to p-nitrophenyl phosphate and uncompetitive with respect to ATP. The drug reduced the steady state level of the phosphoenzyme but not the observed rate constant for phosphoenzyme formation in the absence of K+ nor the quantity of phosphoenzyme reacting with K+. The drug quenched the fluorescence of fluorescein isothiocyanate-modified enzyme and also inhibited the ATP-independent K+ exchange reaction of the H+,K+-ATPase. Its action on gastric acid secretion can be explained by inhibition of the H+,K+-ATPase by reversible complexation of the enzyme. This class of compound, therefore, acts as a reversible inhibitor of gastric acid secretion.

In order to determine the role of divalent cations in the reaction mechanism of the H+,K+-ATPase, we have substituted calcium for magnesium, which is required by the H+,K+-ATPase for phosphorylation from ATP and from PO4. Calcium was chosen over other divalent cations assayed (barium and manganese) because in the absence of magnesium, calcium activated ATP hydrolysis, generated sufficiently high levels of phosphoenzyme (573 +/- 51 pmol.mg-1) from [gamma-32P]ATP to study dephosphorylation, and inhibited K+-stimulated ATP hydrolysis. The Ca2+-ATPase activity of the H+,K+-ATPase was 40% of the basal Mg2+-ATPase activity. However, the Ca2+,K+-ATPase activity (minus the Ca2+ basal activity) was only 0.7% of the Mg2+,K+-ATPase, indicating that calcium could partially substitute for Mg2+ in activating ATP hydrolysis but not in K+ stimulation of ATP hydrolysis. Approximately 0.1 mM calcium inhibited 50% of the Mg2+-ATPase or Mg2+,K+-ATPase activities. Inhibition of Mg2+,K+-ATPase activity was not competitive with respect to K+. Inhibition by calcium of Mg2+,K+ activity p-nitrophenyl phosphatase activity was competitive with respect to Mg2+ with an apparent Ki of 0.27 mM. Proton transport measured by acridine orange uptake was not detected in the presence of Ca2+ and K+. In the presence of Mg2+ and K+, Ca2+ inhibited proton transport with an apparent affinity similar to the inhibition of the Mg2+, K+-ATPase activity. The site of calcium inhibition was on the exterior of the vesicle. These results suggest that calcium activates basal turnover and inhibits K+ stimulation of the H+,K+-ATPase by binding at a cytosolic divalent cation site. The pseudo-first order rate constant for phosphoenzyme formation from 5 microM [gamma-32P]ATP was at least 22 times slower in the presence of calcium (0.015 s-1) than magnesium (greater than 0.310 s-1). The Ca.EP (phosphoenzyme formed in the presence of Ca2+) formed dephosphorylated four to five times more slowly that the Mg.EP (phosphoenzyme formed in the presence of Mg2+) in the presence of 8 mm trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA) or 250 microM ATP. Approximately 10% of the Ca.EP formed was sensitive to a 100 mM KCl chase compared with greater than 85% of the Mg.EP. By comparing the transient kinetics of the phosphoenzyme formed in the presence of magnesium (Mg.EP) and calcium (Ca.EP), we found two actions of divalent cations on dephosphorylation.(ABSTRACT TRUNCATED AT 400 WORDS)