Search

Diabetic kidney disease is a major cause of premature mortality in type 2 diabetes mellitus (T2DM). Worsening insulin sensitivity independent of glycemic control may contribute to the development of diabetic kidney disease. We investigated the longitudinal association of insulin sensitivity with hyperfiltration and increased albumin excretion in adolescents with T2DM.

Objective:Obstetric brachial plexus palsy (OBPP) at birth, is a serious neurologic injury that may lead to a long lasting disability. We aimed to examine the occurrence and risk factors associated with disability lasting >1 year.Study Design:A retrospective cohort study conducted between 1993 and 2012 included individuals with diagnosis of OBPP at birth. Affected individual’s motor function was evaluated by a direct physical exam based on a muscle grading system of the limb, shoulder, elbow and hand. When not feasible a telephone questionnaire was used. Participants reported on activities of daily living, disability duration and any type of intervention. Stepwise logistic regression model was used to identify demographic and obstetric risk factors for disability lasting >1 year.Results:Of all 83 806 deliveries during this period, 144 OBPP cases were identified (1.7/1000). Of the 91 (63.2%) individuals located 42 (46.2%) were evaluated by a physical exam and 49 (53.8%) answered a telephone questionnaire. In 12 (13.2%) disability lasted >1 year. Significant predictors for disability lasting >1 year included birthweight >4 kg (P=0.02; odds ratio (OR) 6.17; 95% confidence interval (CI) 1.33–28.65) and younger maternal age (P=0.02; OR 0.84; 95% CI: 0.73–0.97). OBPP decreased 16% per 1 year increase in maternal age.Conclusions:OBPP is a transient injury in most cases. Birthweight over 4 kg and younger maternal age maybe associated with disability lasting >1 year.

Context:Steroid sex hormones and SHBG may modify metabolism and diabetes risk, with implications for sex-specific diabetes risk and effects of prevention interventions.Objective:This study aimed to evaluate the relationships of steroid sex hormones, SHBG and SHBG single-nucleotide polymorphisms (SNPs) with diabetes risk factors and with progression to diabetes in the Diabetes Prevention Program (DPP).Design and Setting:This was a secondary analysis of a multicenter randomized clinical trial involving 27 U.S. academic institutions.Participants:The study included 2898 DPP participants: 969 men, 948 premenopausal women not taking exogenous sex hormones, 550 postmenopausal women not taking exogenous sex hormones, and 431 postmenopausal women taking exogenous sex hormones.Interventions:Participants were randomized to receive intensive lifestyle intervention, metformin, or placebo.Main Outcomes:Associations of steroid sex hormones, SHBG, and SHBG SNPs with glycemia and diabetes risk factors, and with incident diabetes over median 3.0 years (maximum, 5.0 y).Results:T and DHT were inversely associated with fasting glucose in men, and estrone sulfate was directly associated with 2-hour post-challenge glucose in men and premenopausal women. SHBG was associated with fasting glucose in premenopausal women not taking exogenous sex hormones, and in postmenopausal women taking exogenous sex hormones, but not in the other groups. Diabetes incidence was directly associated with estrone and estradiol and inversely with T in men; the association with T was lost after adjustment for waist circumference. Sex steroids were not associated with diabetes outcomes in women. SHBG and SHBGSNPs did not predict incident diabetes in the DPP population.Conclusions:Estrogens and T predicted diabetes risk in men but not in women. SHBG and its polymorphisms did not predict risk in men or women. Diabetes risk is more potently determined by obesity and glycemia than by sex hormones.

Abstract.: While most researchers agree on the global features of cooperative ligand binding to haemoglobin (Hb), the internal mechanisms remain open to debate. This is not due to inaccurate measurements, but is rather a consequence of the cooperative ligand binding that decreases the equilibrium populations of the partially liganded states and makes observation of the transitions between these substates more difficult. For example, the equilibrium population of the doubly liganded tetramers is typically less than 5% of the total Hb. As a result many models with widely varying mechanisms may fit the oxygen equilibrium curve, but may not be consistent with observations of other parameters, such as ligand-binding kinetics or subunit association equilibria. The wide range of methods and models has led to divergent conclusions about the properties of specific substates. One notable debate concerns the properties of the doubly liganded forms. The simple two-state model predicts a shift in the allosteric equilibrium based on the number of ligands bound, but not on their distribution within the tetramer. From studies of dimer-tetramer equilibria of various pure and hybrid forms, it was concluded that a tetramer with two ligands bound on the same α β dimer (species 21, an asymmetric hybrid) shows an enhanced tetramer stability, similar to singly liganded Hb, relative to the other three types of doubly liganded tetramers which resemble the triply liganded forms [Ackers et al. (1992), Science 255: 54–63]. The implications of this model and the relevant experiments will be reviewed here.

Saccharomyces cerevisiae cells lacking the SEP1 (also known as XRN1, KEM1, DST2, RAR5) gene function exhibit a number of phenotypes in cellular processes related to microtubule function. Mutant cells show increased sensitivity to the microtubule‐destabilizing drug benomyl, increased chromosome loss, a karyogamy defect, impaired spindle pole body separation, and defective nuclear migration towards the bud neck. Analysis of the arrest morphology and of the survival during arrest strongly suggests a structural defect accounting for the benomyl hypersensitivity, rather than a regulatory defect in a checkpoint. Biochemical analysis of the purified Sep1 protein demonstrates its ability to promote the polymerization of procine brain and authentic S.cerevisiae tubulin into flexible microtubules in vitro. Furthermore, Sep1 co‐sediments with these microtubules in sucrose cushion centrifugation. Genetic analysis of double mutant strains containing a mutation in SEP1 and in one of the genes coding for alpha‐ or beta‐tubulin further suggests interaction between Sep1 and microtubules. Taken together these three lines of evidence constitute compelling evidence for a role of Sep1 as an accessory protein in microtubule function in the yeast S.cerevisiae.

Decreased intestinal absorption of Ca2+ occurs in response to treatment with disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP). The effect is due to decreased 1-hydroxylation of calcidiol (25-hydroxycholecalciferol) in the kidney. In an attempt to establish whether impairment of vitamin D metabolism at steps beyond kidney hydroxylation occurs due to treatment with EHDP, chicks were depleted of vitamin D and were treated with calcitriol (1,25-dihydroxycholecalciferol) as their sole source of the vitamin. The chicks were then divided into two groups, one being treated with EHDP while the second group served as control. Intestinal absorption of Ca2+ in the EHDP-treated group was found to be impaired, along with decreases in concentrations of calbindin D28K (the 28,000-Mr vitamin D-dependent Ca2+-binding protein). When the chicks were dosed with [3H]calcitriol, significantly lower concentrations of the sterol were detected in the duodena of EHDP-treated birds. Measurement of levels of receptors for calcitriol in duodena showed no difference between groups, but levels of calcitriol in sera were considerably lower in the EHDP-treated group along with the elevated biliary and urinary excretion of glucuronidated conjugates. It is therefore concluded that treatment with EHDP results in increased catabolism of calcitriol in addition to the known suppression of the renal production of the hormone.

A 13-year-old girl with total alopecia who in infancy had rickets unresponsive to large doses of vitamin D2is described. She had profound hypocalcæmia which was resistant to treatment with high doses of dihydrotachysterol, 1α-hydroxycholecalciferol, and 1,25-dihydroxycholecalciferol. Serum concentrations of 25-hydroxyvitamin D were normal but those of 1,25-dihydroxycholecalciferol were markedly raised (674 and 745 pg/ml). In addition, 24,25-dihydroxyvitamin D was undetectable in serum. Administration of synthetic 24,25-dihydroxycholecalciferol was followed by normocalcæmia which persisted long after treatment was stopped. Her sister, who died at the age of 10 months, also had had total alopecia, rickets, and hypocalcæmia resistant to vitamin-D2therapy. In this familial syndrome there seems to be end-organ resistance to the action of 1,25-dihydroxycholecalciferol, possibly as a result of changes at the receptor sites.

Background. Previous studies have reported weak relationships between health beliefs and behavior change; few studied elderly populations. Methods. We examined the relation between self-reported behavior change and health-related beliefs among an educated, upper-middle-class population age 50 to 89 years. Results. More women reported decreasing dietary salt and fat, changing diet, and reading self-help materials than men. Younger respondents (age 50 to 69 years) reported more positive health behavior changes in diet and exercise than did older respondents (age 70 to 89 years). Respondants who agreed that diet and exercise were important for optimal health and/or spent money on healthful items reported more positive behavior change than those who disagreed. Those who reported confusion about how to stay healthy or a lack of motivation to engage in healthful behaviors were less likely to make positive lifestyle changes. Older respondents reported a higher rate of confusion regarding which foods to eat (53% vs 39%) and how to stay healthy (29% vs 19%) than younger respondents, while younger respondents were more likely to report a problem with motivation (40% vs 34%). Conclusions. These results suggest that increasing age does not diminish the relation between health beliefs and health behaviors. Health promotion campaigns aimed at older adults should strive to reduce confusion to improve health behavior.Copyright 1994, 1999 Academic Press, Inc.

Polymerization of the deoxy form of sickle cell hemoglobin (Hb S; beta 6 Glu----Val) involves both hydrophobic and electrostatic intermolecular contacts. These interactions drive the mutated molecules into long fibrous rods composed of seven pairs of strands. X-ray crystallography of Hb S and electron microscopy image reconstruction of the fibers have revealed the remarkable complementarity between one of the beta 6 valines of each molecule (the donor site) and an acceptor site at the EF corner of a neighboring tetramer. This interaction constitutes the major lateral contact between the two strands in a pair. To estimate the relative importance of this key hydrophobic contact in polymer formation we have generated a polymerizing Hb with isoleucine at the beta 6 position (beta E6I) by site-directed mutagenesis. The mutated beta chains were produced in Escherichia coli and reassembled into functional tetramers with native alpha chains. Compared to native Hb S, the beta E6I mutant polymerizes faster and with a shortened delay time in 1.8 M phosphate buffer, indicating an increased stability of the nuclei preceding fiber growth. The solubility of the beta E6I mutant Hb is half that of native Hb S. Computer modeling of the donor-acceptor interaction shows that the presence of an isoleucine side chain at the donor site induces increased contacts with the receptor site and an increased buried surface area, in agreement with the higher hydrophobicity of the isoleucine residue. The agreement between the predicted and experimental differences in solubility suggests that the transfer of the beta 6 valine or isoleucine side chain from water to a hydrophobic environment is sufficient to explain the observations.

The colonization by streptomycin-resistant Streptococcus mutans strains of the teeth of conventional and ex-germfree Sprague-Dawley rats of various ages fed either a high-sucrose or a high-glucose diet was studied. Bacterial colonization occurred with increasingly greater difficulty as the rats became older. This was observed in studies of the implantation of the test organism after oral inoculation with different cell numbers as well as its transmission between infected and uninfected rats. With rat fed sucrose diet, the effect of age could not be demonstrated until they were age 3 months or older; the results from rats fed a glucose diet suggest that changes may already have occurred early after weaning. Changes in susceptibility to colonization during aging manifested themselves as a decrease in the proportions of rats which became infected as well as lower population levels in infected rats. The possible mechanism(s) involved as well as the possible significance of the findings was discussed.

Our goal was to design a single hemoglobin subunit able to assemble into a stable tetrameric structure with cooperative O2 binding and low oxygen affinity. We have synthesized in E. coll a chimeric β/α globin subunit composed of the first 73 residues of the β chain and the last 73 residues of the α chain. Molecular building indicated that this construction could result in Hb homotetramers possessing the α1β2 interface, responsible for the heme-heme interaction in Hb heterotetramers. The results show that the chimeric subunits assemble into tetramers which bind oxygen reversibly without cooperativity but with an oxygen affinity slightly lower than observed for human Hb. The strong effector RSR 4 lowers the oxygen affinity. Kinetics of CO recombination in the presence of RSR 4 reveal a biphasic bimolecular rebinding. Functional studies suggest that the quaternary structure of the oligomer is intermediary between R-and T-state.

1. Dunaliella bardawil, a β-carotene accumulating halo-tolerant alga, has been tested as a source of retinol in a chick diet.2. Chicks were fed diets deficient in retinol or supplemented with retinol, synthetic β-carotene or dry algae.3. After an initial lag, chicks grew equally well on diets supplemented with algae, retinol or β-carotene.4. Serum and liver analyses revealed a normal content of retinol in all chicks except those grown on the retinol-deficient diet. Chicks fed the algae-supplemented diet contained lutein but no β-carotene in their serum, even though the ratio of β-carotene to lutein in the algae was over 15:1.5. Laying hens fed with an algae-supplemented diet showed enhanced egg yolk colour attributable to a higher lutein content. No β-carotene was present in the egg-yolk.6. These studies demonstrate the possibility of using dried Dunaliella bardawil as a dietary supplement which can fully satisfy the retinol requirement and also serve as a yolk-colour enhancing agent.

OBJECTIVE--To determine whether infants who died of the sudden infant death syndrome routinely shared their parents' bed more commonly than control infants. DESIGN--Case-control study. SETTING--Southern California. SUBJECTS--200 white, African-American, Latin American, and Asian infants who died and 200 living controls, matched by birth hospital, date of birth, sex, and race. MAIN OUTCOME MEASURES--Routine bedding (for example, crib, cradle), day and night time sleeping arrangement (for example, alone or sharing a bed); for cases only, sleeping arrangement at death. Differences in bed sharing practices among races. RESULTS--Of the infants who died of the syndrome, 45 (22.4%) were sharing a bed. Daytime bed sharing was more common in African-American (P < 0.001) and Latin American families (P < 0.001) than in white families. The overall adjusted odds ratio for the syndrome and routine bed sharing in the daytime was 1.38 (95% confidence interval 0.59 to 3.22) and for night was 1.21 (0.59 to 2.48). These odds ratios were adjusted for routine sleep position, passive smoking, breast feeding, intercom use, infant birth weight, medical conditions at birth, and maternal age and education. There was no interaction between bed sharing and passive smoking or alcohol use by either parent. CONCLUSIONS--Although there was a significant difference between bed sharing among African-American and Latin American parents compared with white parents, there was no significant relation between routine bed sharing and the sudden infant death syndrome.

The vitamin D-induced calcium-binding protein calbindin-D (CaBP) was localized immunohistochemically in some but not all of the cell bodies and axons within the intestinalis nerve of the chicken. Unlike other nerve tissue thus far examined, the CaBP content of the intestinalis nerve was decreased in vitamin D deficiency and increased in chicken adapted to a calcium-deficient diet. These changes are qualitatively similar to the pattern of response of enterocytes. The inclusion of calcium-containing solutions within the duodenal lumen caused, directly or indirectly, a decrease in the amount of CaBP in this nerve in a dose-dependent manner. The exact role of CaBP in intestinalis nerve cells is unknown but may be in the regulation of intracellular ionic Ca2+ concentrations during excitation, although other functions of CaBP cannot be excluded.

Hybrid hemoglobin molecules prepared with beta chains from hemoglobin S (beta 6 Glu leads to Val) and alpha chains from hemoglobin Sealy (alpha 47 Asp leads to His) form fibers with a novel structure. In contrast to the typical fibers of hemoglobin S with an average diameter of 22 nm and a solid cross section composed of 10 outer filaments surrounding a 4-filament core, the fibers of the alpha Sealy2 beta S2 hybrid are much larger, with a mean diameter of 32 nm and a unique double-hollow arrangement of filaments. Sealy--S fibers can be described by a model in which the two pairs of filaments most readily lost from fibers of hemoglobin S are missing to form the hollow regions, with an additional sheath of filaments added to form the overall larger structure.

The levels of the active metabolites of vitamin D were measured in the callus and in the epiphyseal growth plate of chicks given radioactive cholecalciferol during fracture healing. Those levels were correlated with the histological findings. Three groups of chicks were studied: a control group with no fracture, chicks with fractures fixed by Kirschner wire, and chicks with unfixed fractures. A significant increase in the levels of the active metabolites was found in the callus during the first few days after fracture. The levels of 25-hydroxycholecalciferol [25(OH)D3] and of 24,25-dihydroxycholecalciferol [24,25(OH)2D3] were higher when there was no fixation, while those of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] were higher after fixation. The concentrations of these metabolites in the proximal epiphysis of the tibia were similar to those found in the callus. Based on these findings it is suggested that the active metabolites of vitamin D are directly involved in the process of fracture repair.

Injection of 1,25 dihydroxycholecalciferol (1,25(OH)2D3, 10 μg) directly into the in situligated duodenal loop of rachitic chicks significantly elevated the tissue accumulation of 47Ca within 20–30 min. The transfer of 47Ca from lumen to blood, during the same time period, was not increased nor was there any measurable intestinal calcium-binding protein synthesized. Lesser amounts of 1,25(OH)2D3(1 or 5 μg) did not result in any statistically significant elevation of 47Ca tissue accumulation, nor did they have any effect on 47Ca transfer from lumen to blood (transmural). Ten micrograms of 1,24R,25(OH)3D3was similarly effective in elevating tissue accumulation, whereas 24R,25(OH)2D3and 25(OH)D3were not. These results provide additional evidence for an early and direct action of 1,25(OH)2D3in altering intestinal epithelial membrane transport prior to the induction of synthesis of specific transport proteins.

The bovine and chick vitamin D-induced intestinal calcium-binding proteins (CaBP) bind lead. Bovine CaBP binds 2 atoms of lead/molecule, and chick CaBP binds 4 atoms of lead per molecule and these values are identical to those for calcium binding. 45Calcium-displacement studies indicate significantly higher affinities for lead than for calcium for both proteins. All evidence indicates that lead is bound to the 4 high affinity calcium-binding sites on chick CaBP and to the corresponding 2 high affinity sites on bovine CaBP, and that binding of lead to sulfhydryl groups is, relatively, not significant. Calmodulin, troponin C, and oncomodulin also bind lead with high affinities and in preference to calcium, indicating that lead binding is a general property of proteins belonging to the troponin C superfamily of calcium-binding proteins.

The relation of fasting and 2-hour serum insulin to the risk for fatal cardiovascular disease was examined in men and women without diabetes. Between 1984 and 1987, 80% of all surviving local members of the Rancho Bernardo Study cohort had measures of insulin and glucose levels obtained before and after a 75-g oral glucose tolerance test. Over the next 5 years, there were 24 cardiovascular disease deaths among 538 men and 21 cardiovascular disease deaths among 705 women. Fasting insulin was unrelated to cardiovascular disease death in men or women; 2-hour insulin was significantly lower in men (but not in women) who died from cardiovascular disease. In men, a 1-standard deviation increase in 2-hour insulin was associated with a 36% reduction in cardiovascular disease mortality (p = 0.01). The significant inverse association of 2-hour insulin with cardiovascular disease death persisted in multiply adjusted models (relative hazard = 0.68; 95% confidence interval 0.47-0.96). Patterns were similar when the analysis was repeated, including men with non-insulin-dependent diabetes mellitus or heart disease at baseline. These findings were not explained by antihypertensive drug use or cigarette smoking. Hyperinsulinemia was not a risk factor for cardiovascular disease in these older men or women. The role of insulin as a cardiovascular disease risk factor requires further investigation.

This cross-sectional study of the Rancho Bernardo, California, cohort examines the relation between bone mineral density and eight measures of body size (total weight, body mass index, waist-hip ratio, lean mass, fat mass, percentage fat mass, and current and maximum adult height) measured between 1988 and 1991 in 1,492 ambulatory white adults aged 55-84 years. Lean mass, fat mass, and percentage fat mass were measured by bioelectric impedance. Bone mineral density was measured at the hip and lumbar spine with dual-energy x-ray absorptiometry and at the midshaft and ultradistal radius with single photon absorptiometry. In multiple linear regression models adjusted for age, smoking, exercise, alcohol, thiazide use, and estrogen use (in women), total weight was the most consistent marker of bone mineral density overall. In this cohort, all measures of body size were associated with bone mineral density in both sexes and were better markers of bone mineral density in the weight-bearing sites than in the non-weight-bearing sites, implying a mechanical effect of weight on bone mineral density.

The relation between fasting plasma glucose and mortality from ischemic heart disease was examined in a population of 3,458 nondiabetics (aged 40-79 years) in Rancho Bernardo, California, who were free of heart disease at baseline and were followed for an average of 14 years, from 1972 to 1987. A linear increase of age-adjusted ischemic heart disease mortality rates with fasting glucose was observed in men, and a threshold relation at 110 mg/100 ml plasma glucose was observed in women. On the basis of Cox proportional hazards analysis, the observed sex differential in the association between plasma glucose and ischemic heart disease mortality proved to be statistically significant and independent of the effects of age, systolic blood pressure, body mass index, plasma cholesterol, plasma triglyceride, and, in women, estrogen use. In sex-specific multivariate models, interaction terms representing a threshold effect at glucose levels greater than or equal to 110 mg/100 ml were statistically significant in women (p = 0.007), but not in men, and interaction between sex and the glucose threshold term was observed in multivariate analysis of men and women combined (p = 0.07). The authors conclude that sex differences in the effect of fasting glycemia on ischemic heart disease mortality among nondiabetics exist and are unexplained. Elucidation may hold a key to the sex difference in heart disease and the relatively greater importance of diabetes and impaired glucose tolerance as risk factors for ischemic heart disease in women compared with men.

G. Weber [(1984) Proc. Natl. Acad. Sci. USA 81, 7098-7102] has inferred that the Monod-Wyman-Changeux (MWC) model for ligand binding by hemoglobin would require (contrary to experimental evidence) that increased ligand binding must promote stabilization of alpha 2 beta 2 tetramers with respect to dissociation into alpha beta dimers. Reexamination of the MWC model, however, in the light of general linkage principles and the specific analysis by G. K. Ackers and M. L. Johnson [(1981) J. Mol. Biol. 147, 559-582] shows that the opposite relation must hold, in agreement with experiment. The T form of the tetramer, with low ligand affinity, must be destabilized and progressively dissociates into the high-affinity dimers, designated D, as ligand binding increases. Each ligand molecule bound shifts the standard Gibbs free energy delta G2T for the D-T equilibrium by approximately 3 kcal/mol in favor of the dimer. Thus, T must exist in (at least) five delta G levels of cooperative free energy as it becomes progressively destabilized by successive binding of ligand molecules. Dissociation of the R tetramer to dimers, in contrast, is independent of the amount of ligand bound, so long as dimers and R-state tetramers possess the same (high) affinity for ligand. While the intrinsic ligand-binding constants of the T and R states (KT and KR) remain unchanged throughout by the postulates of the model, the model should not be regarded as a strictly two-state system in view of the multiple free-energy levels indicated above. The present analysis gives approximate, though not precise, agreement with experimental findings on the dimer-tetramer equilibrium considered by Weber and provides a rationale for interpreting other recent experiments concerning this equilibrium.

1. The effect of bicarbonate (NaHCO3) feeding on intestinal absorption of calcium and phosphorus and vitamin D metabolism was investigated. Gut sac uptake of 45Ca and [32P]phosphate in vitro, as well as the plasma level of vitamin D metabolites, was determined in rats fed with NaHCO3 for 9 days and their pair-fed controls. 2. Duodenal uptake of 45Ca and [32P]phosphate by alkalotic rats was less than duodenal uptake by controls. 1,25(OH)2D plasma level was much higher in alkalotic rats than in their controls, and 25(OH)D slightly higher than in controls. 3. These data suggest that NaHCO3 feeding causes a substantial increase in 1,25(OH)2D plasma level, but interferes with calcium and phosphorus absorption in the duodenum.

1. One-day-old chicks were depleted of vitamin D. At 3 weeks their right tibiae, and those of a control group given vitamin D3, were fractured and pinned. After fracture the controls were kept on vitamin D3. Another group was left vitamin D-deficient. The remaining depleted chicks, divided into four groups, were given vitamin D3, 24,25-dihydroxyvitamin D3 [24,25(OH)2D3], 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] or a combination of 24,25(OH)2D3 and 1,25(OH)2D3. 2. The callus obtained after 9 and 14 days was subjected to torsional stress. The callus of chicks given vitamin D continuously showed the greatest resistance, whereas that of vitamin D-deficient chicks showed the smallest resistance. Repletion with either vitamin D3 or its metabolites increased the strength of the callus. Repletion with the combination of 24,25(OH)2D3 and 1,25(OH)2D3 produced the most marked results, in that the callus was even stronger than that of chicks replete with vitamin D3. 3. It is concluded that 24,25(OH)2D3 is essential for bone formation in addition to the known active vitamin D metabolite 1,25(OH)2D3, and the possible clinical implications of these findings are discussed.

• From among the pregnant women in the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke, we identified 508 who had migraine, and 3192 who had no history of migraine, of taking headache medication during the previous 12 months, and of headaches during the pregnancy. Migraineurs smoked more heavily and had a longer smoking history than their headache-free peers. Among migraineurs, smokers were not more likely to consume analgesics than nonsmokers. Regardless of smoking classification, more migraineurs consumed tranquilizers, amphetamines, and sleeping pills than headache-free women. Among smokers only, migraine was associated with heart disease, thrombosis/ phlebitis, asthma, peptic ulcer, and pneumonia. In nonsmokers, migraine was associated with drug sensitivity and other allergies.

Calcium is one of the most important substances affecting the life of molluscs, and vitamin D was shown to be an essential nutrient for land snails. In an attempt to elucidate the role that vitamin D plays in calcium metabolism of land snails, we have developed a procedure for the isolation of specialized calcium cells from digestive gland of land snails, and were able to culture these cells. The effect of vitamin D metabolites on the intracellular exchangeable calcium and alkaline phosphatase activity was studied. The metabolites tested were 25-hydroxycholecalciferol (25(OH)D3), 24,25-dihydroxycholecalciferol (24,25(OH)2D3), 1,25-dihydroxycholecalciferol (1,25(OH)2D3), and the molluscan metabolite E. 25(OH)D3 was found to be the most active sterol in elevating intracellular exchangeable calcium and the activity of alkaline phosphatase, and the molluscan metabolite E was found to be the most potent sterol in the suppression of alkaline phosphatase activity. 1,25(OH)2D3 was shown to suppress both activities at high concentrations, and 24,25(OH)2D3 increased the intracellular exchangeable calcium only at high concentrations. Thus, 25(OH)D3 which is regarded as a storage form of vitamin D and devoid of biological activity, seems to be biologically active in invertebrates.

Summary: Experimental fractures were performed on tibiae of vitamin D-depleted chicks. The chicks were divided into three groups; they were treated daily with (a) cholecalciferol or (b) 1α-hydroxycholecalciferol (1α(OH)D3), or (c) they received no treatment. Microscopic examination of the calluses formed at the fractured sites and of the proximal tibiae of the contralateral legs showed that treatment with 1α(OH)D3 failed to heal most of the rachitic signs seen in the nontreated chicks, despite normal plasma concentrations of calcium and of inorganic phosphorus. In a second experiment, experimental fractures were performed on tibiae of chicks that were fed a vitamin D-deficient diet, but were dosed continuously with radioactive cholecalciferol. Analysis of cholecalciferol metabolites in the callus tissue showed perferential accumulation of 25-hydroxycholecalciferol (25(OH)D3) and of 24,25-dihydroxycholecalciferol (24,25(OH)2D3). Very little 1α, 25-dihydroxycholecalciferol (1α,25(OH)2D3) was detected in bones or in calluses. Based on the data obtained, the following conclusions were drawn: (a) that cholecalciferol is directly involved in bone formation; and (b) that 1α, 25(OH)2D3 is not the sole metabolite of cholecalciferol involved in this process.

Intracellular exchangeable calcium and calcium efflux were investigated in cultured amoebocytes of land snails. Low extracellular calcium concentration (0.32 mM) initiated a rapid increase of outward calcium currents and decrease of intracellular exchangeable calcium. On the other hand, high extracellular calcium concentration (32 mM) increased intracellular exchangeable calcium. Actions of vitamin D metabolites were most prominent under non-physiological concentrations of extracellular calcium. Metabolite E activated a calcium pump while 25-hydroxy-vitamin D3deactivated the pump. Both metabolites increased calcium transfer into stored pools.

The perturbations of the conformation of human deoxyhemoglobin induced by the covalent attachment of glutathione at cysteine beta 93 have been investigated by computer simulation in conjunction with molecular graphics. In the first phase of the analysis, a systematic search was carried out of the conformational space of glutathione attached to deoxyhemoglobin. In this search, the conformation of the hemoglobin molecule was held constant, while the relative energies of a series of 186,624 glutathione conformations involving systematic variation of six dihedral angels were calculated. From this search, the most favorable conformation was selected as the starting conformation for energy minimization of the glutathionyl hemoglobin molecule as a function of all Cartesian coordinates. In order to provide a reference state, an independent minimization by the same procedures was carried out for deoxyhemoglobin in the absence of glutathione. Comparison of the minimized structures with and without glutathione attached revealed a number of significant differences. The most conspicuous difference in the protein moiety concerned the salt bridge between aspartate beta 94 and histidine beta 146 which is destabilized upon minimization of the glutathionyl-hemoglobin complex due to interactions of the aspartate residue with the glycyl NH group of glutathione. Other observed differences in the minimized structures are located at the alpha 1-beta 2 interface and include displacement of the carboxyl group of aspartate beta 99. In the minimized complex, the glutathione portion assumes a quasi-cyclic conformation stabilized through interactions between the free (gamma-glutamyl) amino and (glycyl) carboxyl ends of the tripeptide and between this carboxyl end and the epsilon amino group of lysine alpha 40. In a parallel conformational study of glutathione alone, a similar structure was found as the lowest energy form. These quasi-cyclic conformations contrast with the extended structures reported by Wright (Wright, W.B. (1955) Acta Crystallogr. 11, 632-642) for crystals of glutathione where interactions between molecules play a major role. The conclusions of our analysis are in agreement with the experimental investigations reported in the two preceding papers and permit, moreover, a coherent interpretation of the observed functional and structural changes in deoxyhemoglobin induced by glutathione.

Between 1988 and 1991, the relation between leisure time physical activity, bone mineral density (BMD), and osteoporotic fracture was evaluated in a cohort of community-dwelling California adults (1,014 women and 689 men) with a mean age of 73 years. By means of a modified Paffenbarger questionnaire, participants were asked to report exercise from the past year and to recall their level of exercise during three other periods: the teenage years, age 30 years, and age 50 years. The survey asked the number of times strenuous (e.g., jogging), moderate (e.g., fast walking), or mild (e.g., golfing) exercise was undertaken in an average week. A summary score was constructed to represent lifetime exercise. Analysis of the exercise-fracture and exercise-BMD associations were performed using logistic and linear regression analyses, respectively. Linear regression models were controlled for age, body mass index, sex, diagnosis of arthritis, dietary calcium intake, and use of cigarettes, alcohol, thiazides, and estrogen (women only). No association between current or former exercise and BMD at the radius, wrist, or spine was found. A positive association between current exercise and BMD was found at the total hip (p = 0.001) and at each hip component--greater trochanter (p = 0.02), intertrochanter (p = 0.001), and femoral neck (p = 0.02). Mean hip bone densities of strenuous (p = 0.004) and moderate (p = 0.004) current exercisers were higher than those of mild or less than mild exercisers. Lifetime exercise was also positively associated with BMD of the total hip (p = 0.008) and hip components, and demonstrated a borderline-significant association (p = 0.06) with spine BMD. At the hip, each pairwise comparison between the highest and lowest tertiles of lifetime exercise showed a significant difference (p < or = 0.007). Exercise was unassociated with minimal trauma fracture occurring at any site between 1972 and 1991. These data suggest a protective effect of current and lifelong exercise on hip BMD, but not on osteoporotic fracture, in older men and women.

In vitamin D-fed chicks 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 were implanted into experimentally-produced fractures of the mid-tibia. The mechanical and biochemical properties of the tibia were evaluated for two weeks, including torsion tests, measurement of alkaline phosphatase activity, 45Ca incorporation, and Ca2+ content. Both dihydroxylated metabolites of vitamin D3 had a direct effect on endochondral bone formation. 24,25(OH)2D3 strengthened the callus, and raised alkaline phosphate activity in the first seven days after fracture. 1,25(OH)2D3 decreased the strength of the callus concomitant with a reduction in 45Ca incorporation. It is suggested that local application of 24,25(OH)2D3 into fractures may accelerate healing and prevent non-union.

Summary: Chicks were depleted of vitamin D, divided into groups, and treated daily with (a) cholecalciferol, (b) 1α-hydroxycholecalciferol [1α(OH)-D3], (c) 24R, 25-dihydroxycholecalciferol [24R,25-(OH)2D3], or (d) 1α(OH)D3 and 24R,25(OH)2D3. Two additional groups of chicks were studied, one that was continuously depleted of vitamin D, and another that was continuously supplemented with the vitamin, since day 1. After killing, the tibiae were removed and tested for their mechanical properties. Bending load was applied to the midshaft, and the intrinsic properties of this site, its quantity and geometry were analyzed. From a mechanical point of view, the weakest bones found were of birds depleted of vitamin D, whereas the strongest were of those treated with 1α(OH)D3. Only the bones of the 24R,25(OH)2D3-treated or the 1α(OH)D3 and 24R,25(OH)2D3-treated groups of birds showed mechanical properties comparable to those obtained with vitamin D-replete chicks.

Summary: Vitamin D3 deficient (D−) mice show a depressed inflammatory response and both inflammatory peritoneal macrophages and bone marrow polymorphonuclear leukocytes of D− mice exhibit a decreased spontaneous migration under agarose. The impaired phagocytic response of peritoneal macrophages from D− mice can be corrected by incubation with 1,25-dihydroxyvitamin D3 and is not affected by interaction with other vitamin D3 metabolites. Transfer of mice from the D− to the D+ state results in correction of both the inflammatory and the phagocytic response. Intactness of phagocyte function is thus directly dependent on vitamin D3 metabolism.

Background. There have been significant efforts in the United States to lower high cholesterol levels. Studies of men, however, have found a higher total cancer mortality rate at lower levels of plasma cholesterol. Many of these studies have found that lung cancer is more closely associated than other cancers with low cholesterol. Of the studies that include women, none has demonstrated a statistically significant inverse association between low cholesterol and lung cancer. Methods. We examined the relation between very low plasma cholesterol levels (<160 mg/dl) and lung cancer death in an 18-year prospective study of 2,011 men and 2,327 women. Results. After adjusting for age, body mass index, smoking, and education, the relative hazard of lung cancer mortality for those with low cholesterol (<160 mg/dl) compared with all other cholesterol levels (≥ 160 mg/dl) was 1.75 among men (P= 0.28) and 3.29 among women (P= 0.02). Excluding those who died within 5 years of baseline did not change the results. Conclusions. Both men and women with baseline plasma cholesterol levels <160 mg/dl were more likely to die of lung cancer. This difference was statistically significant in women. The association could not be explained by occult malignancy, smoking, or socioeconomic status.

The effect of 24,25-dihydroxyvitamin D3on some of the activities of 1,25-dihydroxyvitamin D3was studied in cultures of cartilage cells obtained from the tibial growth plate of rachitic chicks. The activities that were tested are those associated with intracellular exchangeable calcium, alkaline-phosphatase activity and the incorporation of thymidine and proline. 24,25-dihydroxyvitamin D3was shown in this system to antagonize the suppressive effect of 1,25-dihydroxyvitamin D3on intracellular exchangeable calcium and on proline incorporation. A similar effect on alkaline phosphatase activity and thymidine incorporation was not observed.

Fibers of deoxyHb S have been investigated by thin-section electron microscopy, utilizing a tannic acid embedding procedure. On the basis of numerous measurements of cross-sectional center-to-center distances for adjacent fibers in pairs or arrays, fiber diameters (mean +/- SD) of 205 +/- 5 A in embedded cells and 212 +/- 8 A in embedded hemolysates were obtained. This is an agreement with values obtained by conventional embedding procedures [Crepeau, R. H., Dykes, G., Garrell, R. L. & Edelstein, S. J. (1978) Nature (London) 274, 616--617]. The use of tannic acid has resulted in improved resolution of fiber cross sections, revealing individual strands of Hb S molecules. Because the section thickness corresponds to approximately one-fifth of the fiber helical repeat distance, the strands in projection superimpose to form characteristic image patterns. Additional superposition patterns arise in sections taken at small deviations from perpendicularity to the longitudinal fiber axis. These patterns are consistent with the 14-strand structure for hemoglobin S fibers [Dykes, G., Crepeau, R. H. & Edelstein, S. J. (1978) Nature (London) 272, 506--510], as indicated by computer models of cross-sectional patterns for various thicknesses and angular deviations of sections.

Mills and Ackers (Mills, F.C., and Ackers, G.K. (1979) J. Biol. Chem. 254, 2881-2887) have reported the subunit interactions of hemoglobin to decrease on binding of the fourth molecule of oxygen to hemoglobin. This effect, which they called quaternary enhancement, is incompatible with the two-state Monod, Wyman, and Changeux allosteric model. Their free energy of binding of the fourth molecule (-9.3 kcal/mol) has been compared with independent kinetic estimates which give -8.6 kcal/mol. This smaller value is consistent with literature values and allows reasonable representation of the equilibrium curve using the two-state model without invoking quaternary enhancement.

A key statement of the 1965 Monod-Wyman-Changeux (MWC) model for allosteric proteins concerns the distinction between the ligand-binding function ( ) and the relevant state function ( ). Sequential models predict overlapping behavior of the two functions. In contrast, a straightforward experimental consequence of the MWC model is that for an oligomeric protein the parameters which characterize the two functions should differ significantly. Two situations, where \bar Y$$ " /> and the system ishyper-responsive or where and the system ishypo-responsive, have been encountered. Indeed, the hyper-responsive pattern was first observed for the enzyme aspartate transcarbamoylase, by comparing with monitored by a change in sedimentation. Extensions of the theory to ligand-gated channels led to the suggestion that, on the one hand, hyper-responsive properties also occur with high-affinity mutants. On the other hand, native channels of the acetylcholine neuronalα7 receptor and low-affinity mutants of the glycine receptor can be interpreted in terms of the hypo-responsive pattern. For the ligand-gated channels, whereas is detected directly by ion flux, ligand binding has rarely been measured and the formation of desensitized states may complicate the analysis. However, stochastic models incorporating both binding and channel opening for single molecules predict differences that should be measurable with new experimental approaches, particularly fluorescence correlation spectroscopy.

The purpose of this study was to prospectively examine the relation of dehydroepiandrosterone sulfate (DHEAS) to bone mineral density in a community-based sample of 260 men and 162 women who were residents of Rancho Bernardo, California. DHEAS levels had been measured in plasma obtained in 1972-1974 when the men were 50-74 years of age and the women were 55-74. In 1988-1991, bone mineral density was measured at the lumbar spine and hip using dual x-ray absorptiometry, and at the mid-radius and ultradistal radius using single photon absorptiometry. Among men, there was a significant decrease in DHEAS levels and bone mineral density at the hip, ultradistal radius, and midshaft radius with increasing age. However, for both men and women, there was no significant association of DHEAS levels with bone mineral density at any site, both before and after adjustment for age, obesity, cigarette smoking, and use of antihypertensive medications. These data do not support the hypothesis of DHEAS having a causal role in senile osteoporosis.