Updated assessment of occupational safety and health hazards of climate change

Workers, particularly outdoor workers, are among the populations most disproportionately affected by climate-related hazards. However, scientific research and control actions to comprehensively address these hazards are notably absent. To assess this absence, a seven-category framework was developed in 2009 to characterize the scientific literature published from 1988-2008. Using this framework, a second assessment examined the literature published through 2014, and the current one examines literature from 2014-2021. The objectives were to present literature that updates the framework and related topics and increases awareness of the role of climate change in occupational safety and health. In general, there is substantial literature on worker hazards related to ambient temperatures, biological hazards, and extreme weather but less on air pollution, ultraviolet radiation, industrial transitions, and the built environment. There is growing literature on mental health and health equity issues related to climate change, but much more research is needed. The socioeconomic impacts of climate change also require more research. This study illustrates that workers are experiencing increased morbidity and mortality related to climate change. In all areas of climate-related worker risk, including geoengineering, research is needed on the causality and prevalence of hazards, along with surveillance to identify, and interventions for hazard prevention and control.

Longitudinal study of effects of alcohol use and/or personal exercise on high density lipoprotein cholesterol in aging humans

Self-controlled alcohol use and/or personal physical exercise is generally believed to be advantageous in extending good health in aging humans. We investigated whether data collected over 31 years in the same subjects (369 men, 75 women) in our Longitudinal Aging Study of humans (1969-2000) showed strong relationship between alcohol and/or physical exercise with High Density Lipoprotein Cholesterol (HDLC). Women s HDLC interactions among age, diet, alcohol use and/or exercise were not found to be statistically significant in our study. Men, however, showed a strong positive statistical significance (p<or= 0.0001) among alcohol, personal physical exercise and HDLC.

Cardiovascular complications of weight reduction diets

Weight reduction diets may reduce the severity of risk factors for coronary heart disease such as diabetes mellitus, hypertension, and dyslipidemia. Several case reports and small studies of patients receiving starvation diets have reported hypotension and sudden cardiac death. Myofibrillar damage was documented in 1 case. Very-low-calorie diets are generally safe and well-tolerated. However, low QRS voltage, QT interval prolongation, and both nonsustained ventricular arrhythmias and sudden cardiac death have been described in subjects treated with such diets. Orthostatic hypotension may complicate very-low-calorie protein diets because of sodium depletion and depressed sympathetic nervous system activity. Bariatric surgery is associated with disproportionately high mortality rates in both the perioperative and postoperative periods.

Facile entry to the tetracyclic 5-7-6-3 tigliane ring system

[figure: see text] A tandem anionic 5-exo-dig cyclization/Claisen rearrangement sequence was used to effect a facile, "one-pot" conversion of an appropriately substituted 4-alkyn-1-ol to the tetracyclic carbon core structure of phorbol. The synthesis was conducted using readily available nonracemic starting materials to provide the target structure as a single enantiomer in high chemical yield.

Electromagnetic guidance for catheter-based transendocardial injection: a platform for intramyocardial angiogenesis therapy. Results in normal and ischemic porcine models

OBJECTIVES

To test the feasibility of myocardial angiogenic gene expression using a novel catheter-based transendocardial injection system.

BACKGROUND

Angiogenesis has been induced by direct injection of growth factors into ischemic myocardium during open-heart surgery. Catheter-based transendocardial injection of angiogenic factors may provide equivalent benefit without need of surgery.

METHODS

A new guidance system for intramyocardial therapy utilizes magnetic fields and catheter-tip sensors to locate a position in space and reconstruct three-dimensional left ventricular (LV) electromechanical maps without using fluoroscopy. A retractable 27G needle was coupled with the guidance system for LV transendocardial injection. In 12 pigs, the catheter was used to inject 0.1 ml of methylene-blue (MB) dye and 8 pigs had myocardial injections of adenoviral vector (1 x 10(10) particles per site) containing the LacZ transgene. Ten pigs underwent catheter-based transendocardial injection and six pigs were injected using transepicardial approach with the gene encoding adenovirus vascular endothelial growth factor-121 (Ad.VEGF121; 1 x 10(10) viral particles x 6 sites) and sacrificed at 24 h. Injection sites were identified with ultraviolet light by coinjection of fluorescent beads.

RESULTS

Overall, 138 of 152 attempted injection MB tracks (91%) were found after sacrifice. Tissue staining was 7.1+/-2.1 mm in depth and 2.3+/-1.8 mm in width. No animal had pericardial effusion or tamponade. In Ad.LacZ injected animals, gross pathology showed positive staining in injected zones, and histology confirmed positive myocyte staining. Adenovirus vascular endothelial growth factor-121 injected sites showed high levels of VEGF121 production that was of similar magnitude whether injected using the transendocardial (880.4+/-412.2 pg VEGF121/mg protein) or transepicardial (838.3+/-270 pg VEGF121/mg protein) delivery approach (p = 0.62).

CONCLUSIONS

Using this magnetic guidance catheter-based navigational system, transgenes can effectively be transfected into designated myocardial sites. Thus, if it is determined that direct intramyocardial injection of angiogenic factors enhances collateral function in patients, this less invasive catheter-based system offers a similar gene delivery efficiency and, thus, may have clear advantages compared with the surgically-based transepicardial injection approach.

Use of fluorescent microspheres to localize in vivo gene transfer injection sites

The potential for using gene therapy to treat a variety of disease states is growing rapidly. Many vector types and delivery systems have been developed that allow the optimization of protein production levels and kinetics for a given therapeutic gene product. In cases in which a transient, localized delivery of gene product is desired, any determination of the locale of transfected tissue by non-marker genes is problematic. We describe a technique by which the use of fluorescent microspheres can help in identifying potentially transfected tissue. Adenovirus containing the gene for beta-galactosidase (beta-gal) was mixed with fluorescent microspheres and injected into rat skeletal muscle and porcine myocardium. The injection sites could be visualized under ultraviolet light and correlated with beta-gal enzyme expression. This method is simple, inexpensive and generally useful for in vivo gene transfer experiments.

Butenolide endothelin antagonists with improved aqueous solubility

Continued development around our ETA-selective endothelin (ET) antagonist 1 (CI-1020) has led to the synthesis of analogues with improved aqueous solubility profiles. Poor solubility characteristics displayed by 1 required a complex buffered formulation in order to conduct iv studies. To overcome the use of specific iv formulations for preclinical studies on additional drug candidates, analogues with improved aqueous solubility were desired. Several analogues were synthesized with substitution patterns that allowed for the formation of either acid or base addition salts. These derivatives had dramatically improved aqueous solubility. In addition, these analogues retained equivalent or improved ETA receptor selectivity and antagonist potency, versus 1, both in vitro and in vivo. Compound 29, which contains as a substituent the sodium salt of a sulfonic acid, has an ETA IC50 = 0.38 nM, ETA selectivity of 4200-fold, and ETA functional activity of KB = 7.8, all of which are similar or superior to those of 1. Compound 29 also has vastly superior aqueous solubility and solubility duration, compared to 1. Furthermore, 29 after iv infusion displays improved activity to 1 in preventing acute hypoxia-induced pulmonary hypertension in rats with an ED50 = 0.3 microg/kg/h.

Dehydroepiandrosterone replacement in aging humans

Because so much medical and media attention has been drawn to the alleged benefits of dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS), it is important to evaluate the effects of replacement therapy objectively using double blind, cross-over, randomized research methodology. In this 9-month study, healthy older men (n = 39) received replacement dose DHEA. Lean body mass, blood hematology, chemistry and endocrine values, as well as urological and psychological data were measured. Data showed some mild and temporary, but significant, changes during oral use of 100 mg DHEA for 3 months compared with placebo taken for 3 months. Body composition did not change during the 6 months of treatment, nor did any urological parameters. Concomitant with the endocrine changes, some small but, significant, variations in blood values (blood urea nitrogen, creatinine, uric acid, alanine transaminase, cholesterol, high density lipoprotein, and potassium) were found. After cessation of DHEA and placebo, followed by 3 months of no treatment, all values previously found to be altered returned to entry baseline. Well publicized effects of the drug reported by others, such as a sense of well-being or improved sexual function, were not found in this study.

An approach to the development of food-based dietary guidelines for Ireland

The aim of the present study was to analyse the different food and nutrient intakes of the adult Irish population from the lowest and highest quartiles of intake for total fat (%energy) dietary fibre (g/MJ) and fruit and vegetables (g/day). Data on Irish adults (n = 715) from the Irish National Nutrition Survey conducted in 1989 were used for the analyses and showed that the average diet is low in dietary fibre, with fruit and vegetables being only half the recommended level of 400 g. Comparisons of people with low or high intakes (from lowest and highest quartiles) of total fat (%energy), dietary fibre (g/MJ) and fruit and vegetables (g/day) show patterns of food intake differing in both the percentage of consumers and in the mean intakes among consumers only. This analysis provides data which may be useful as a first step towards the development of food-based dietary guidelines for Ireland. In particular, the low intake of fruit and vegetables in the adult Irish population deserves special attention.

Avian osteoclast cells are stimulated to resorb calcified matrices by and possess receptors for leukotriene B4

Leukotriene B4 (LTB4) is elevated in inflammatory conditions and appears to be a potential mediator of inflammation. We have recently shown that this 5-lipoxygenase metabolite of arachidonic acid stimulates bone resorption in vitro and in vivo. In order to determine the mechanism whereby LTB4 causes bone resorption, avian osteoclasts were examined for the effects of LTB4 and for the presence of LTB4 receptors. Isolated avian osteoclast mononuclear precursor cells, which fuse in culture to form multinucleated cells, were chosen for receptor binding studies because this population is a morphologically similar source of osteoclasts, and large numbers of these cells can be obtained from egg-laying hens. Binding of LTB4 and activation would support the hypothesis of a direct effect of this compound on osteoclasts. LTB4 stimulated isolated avian osteoclasts to form resorption lacunae on calcified matrices and to increase their content of tartrate-resistant acid phosphatase (TRAP), a marker of activated osteoclasts. Receptor binding studies were performed at day 1, when the cells were mononuclear, at day 4, when mononuclear precursors were actively fusing, and at day 7, when fusion has slowed. Scatchard analysis of saturation binding data showed two classes of binding sites, a high- and low-affinity binding site with dissociation constants (KD) of 0.2-0.4 nM and 5. 6-24 nM. Association studies showed rapid binding of LTB4 to the cells within 10 minutes. These data show that LTB4 accelerates fusion and activates highly enriched populations of avian osteoclasts and that LTB4 receptors are present in this cell population.

Endothelin B receptors on human endothelial and smooth-muscle cells show equivalent binding pharmacology

We have described the pharmacologic profiles of endothelin B receptors in human endothelial cells and vascular and nonvascular smooth-muscle cells. First, by amplifying endothelin B receptor numbers through the use of phosphoramidon and intact cell-binding techniques, we demonstrated the presence of these receptors in human umbilical vein endothelial cells (100% endothelin B receptors), human aortic smooth-muscle cells (22% endothelin B, 78% endothelin A receptors), and human bronchial smooth-muscle cells (55% endothelin B, 45% endothelin A receptors) by using [125I]-endothelin-1 radioligand binding. The typical binding profiles of the endothelin B receptors were established through competition binding curve analysis with endothelin-1, endothelin-3, sarafotoxin 6c, and the endothelin A receptor-selective antagonist BQ-123. In the presence of BQ-123, a diverse group of antagonists, including PD 142893, BQ-788, SB 209670, and Ro 47-0203, were used to probe for binding differences indicative of multiple endothelin B-receptor subtypes. The results indicate a rank order of potency for the antagonists of BQ-788 > SB 209670 > PD 142893 > Ro 47-0203 for each cell line, and that between any of these human cell lines, measurements of [125I]-endothelin-1-binding antagonism for each of the four test compounds differed by less than twofold. Although this study cannot discount the possibility of more than one endothelin B-receptor subtype in humans, it does indicate that these tissues express receptors that show equivalent binding pharmacology.

The pursuit of thinness: a study of Dublin schoolgirls aged 15 y

Despite increasing trends in the prevalence of overweight and obesity, fatness phobia is common during female adolescence. This study has demonstrated a high level of dissatisfaction with body weight in a sample of Dublin schoolgirls aged 15 y. Of 420 subjects, 59% reported that they wanted to be slimmer and 68% had previously tried to lose weight. Contrary to expectations, overweight girls were not found to hold the monopoly on such dissatisfactions. Normal weight and even underweight girls also expressed a desire to be thinner and reported using unhealthy weight control practices including random avoidance of staple foods, fasting, smoking and purging, in their pursuit of the 'perfect' female figure. Obesity prevention programmes which target adolescent girls 'at risk' of overweight and obesity, must take cognizance of their profound fear of fatness, otherwise the use of harmful slimming strategies may be further increased as teenage girls frantically try to lose weight and to avoid the stigma associated with female fatness.

Atherogenesis and the homocysteine-folate-cobalamin triad: do we need standardized analyses?

BACKGROUND

Bioscientists, physicians and nutritionists are newly interested in the homocysteine-folate-cobalamin triad, in part because homocysteine may be important both in atherogenesis and thrombogenesis. Homocysteine imbalance may be an early marker for cobalamin disorders because cobalamin is a cofactor in remethylation of homocysteine to methionine.

METHODS

In 139 men and 32 women of similar mean age of 65 years, we measured markers which have been cited as risk for atherosclerosis: serum homocysteine, folate, total cobalamin, holotranscobalamin I and II, (TCI and TCII), total serum cholesterol (SCHOL), high density lipoprotein cholesterol (HDLC), triglycerides (STG) as well as red blood cell (RBC) folate, food records and body composition by whole body counting of potassium-forty (40K).

RESULTS

Statistical relationships among the data showed healthy women had lower mean serum homocysteine and their mean RBC folate and TCI and TCII were higher than men. Eighty-three subjects had TCII much lower than 60 pg/ml (subnormal), yet only 11 of these men and two women had total cobalamin < 200 pg/ml (abnormal). Fifty-two subjects with serum homocysteine greater than 17.5 nmol/ml had TCII less than 60 pg/ml, suggesting serum homocysteine may be a marker for early cobalamin negative balance. None of the subjects in the study had serum folate below abnormal values, i.e., less than 1.6 mg/ml. All subjects had RBC folate within normal range. Serum homocysteine showed inverse relationship with RBC folate and serum total cobalamin, TCI and TCII.

CONCLUSIONS

1) importance of using serum holotranscobalamin TCI and TCII as markers of cobalamin deficiency, 2) necessity to use documented quantitative components of dietary intake if strong comparisons are to be made among quantitative values of serum or plasma homocysteine, folate, cobalamin, and nutrients in food intake.

Risk factors for recurrence of hemorrhagic endovasculitis of the placenta

OBJECTIVE

To assess the potential for recurrence of placental hemorrhagic endovasculitis and to identify clinical or pathologic cofactors that might influence recurrence of this lesion or subsequent pregnancy outcome.

METHODS

Ninety-seven women with a placenta affected by hemorrhagic endovasculitis, who also had at least one placenta referred to the Michigan Placental Tissue Registry from a subsequent pregnancy, were identified from 10,531 referrals between 1978 and 1988. Histologic slides from 209 placentas and clinical data from 211 infants (two sets of twins) from initial (first) and subsequent referrals were analyzed. Placentas were graded for the presence, extent, and severity of hemorrhagic endovasculitis and chronic villitis of unknown etiology; for placental lesions indicative of hypertensive maternal vessel disease; and for intravascular nucleated erythrocytes and chorionic thrombi. Maternal data included age, gravidity, number of previous losses, and history of toxemia or hypertension. All data were analyzed for significance using chi2 and t tests. Outcome assessment was based on recurrence of hemorrhagic endovasculitis and infant viability with the second referral.

RESULTS

With first referrals, 80 of 98 infants (81.6%) were stillborn. Among second referrals, 26 of 98 infants (26.5%) were stillborn. Hemorrhagic endovasculitis recurred in 28 second placentas (28.9%); of these, 18 infants (64.3%) were stillborn. Higher rates of recurrence were found with progressively higher first-referral chronic villitis severity scores (P < .02), higher hypertensive placental lesion scores (P < .001), and first referrals with a history of toxemia or hypertension (P < .02). Recurrence of hemorrhagic endovasculitis was higher in patients with two or more of these factors in first referrals (P < .001). Subsequent stillbirth was more frequent with progressively higher first-referral hypertensive placental lesion scores (P < .01) and in first placentas with two or more risk factors (P = .064). Hemorrhagic endovasculitis severity scores, intravascular nucleated erythrocytes, and chorionic thrombi were associated with stillbirth in index pregnancies only. Maternal age, gravidity, or history of prior losses were not predictive.

CONCLUSIONS

Placental hemorrhagic endovasculitis is associated with pregnancy loss and can recur in some patients. Interrelations among placental hemorrhagic endovasculitis, chronic villitis, maternal hypertension, and adverse outcomes in subsequent pregnancies are apparent. This information may be useful in patient counseling.

Structure-activity relationships in a series of orally active gamma-hydroxy butenolide endothelin antagonists

The design of potent and selective non-peptide antagonists of endothelin-1 (ET-1) and its related isopeptides are important tools defining the role of ET in human diseases. In this report we will describe the detailed structure-activity relationship (SAR) studies that led to the discovery of a potent series of butenolide ETA selective antagonists. Starting from a micromolar screening hit, PD012527, use of Topliss decision tree analysis led to the discovery of the nanomolar ET(A) selective antagonist PD155080. Further structural modifications around the butenolide ring led directly to the subnanomolar ETA selective antagonist PD156707, IC50's = 0.3 (ET(A)) and 780 nM (ET(B)). This series of compounds exhibited functional activity exemplified by PD156707. This derivative inhibited the ETA receptor mediated release of arachidonic acid from rabbit renal artery vascular smooth muscle cells with an IC50 = 1.1 nM and also inhibited the ET-1 induced contraction of rabbit femoral artery rings (ETA mediated) with a pA2 = 7.6. PD156707 also displayed in vivo functional activity inhibiting the hemodynamic responses due to exogenous administration of ET-1 in rats in a dose dependent fashion. Evidence for the pH dependence of the open and closed tautomerization forms of PD156707 was demonstrated by an NMR study. X-ray crystallographic analysis of the closed butenolide form of PD156707 shows the benzylic group located on the same side of the butenolide ring as the gamma-hydroxyl and the remaining two phenyl groups on the butenolide ring essentially orthogonal to the butenolide ring. Pharmacokinetic parameters for PD156707 in dogs are also presented.

Women's dietary fat and sugar intakes: implications for food based guidelines

OBJECTIVE

To examine how women's dietary data can be used to formulate food based dietary guidelines for fat.

DESIGN

Dietary intake data was assessed cross-sectionally using the 7 d diet history method. Subjects were divided into quartiles on the basis of their intakes of total fat and saturated fatty acids (% energy) and the diets of those in the lowest and highest quartiles were compared.

SUBJECTS AND SETTING

Subjects studied were socially advantaged and disadvantaged women (n = 83, mean age 35 years) recruited from their workplaces.

RESULTS

The inverse relationship between intakes of sugar and total fat (P < 0.0001) found in this study also extended to saturated fatty acids (P = 0.0007). Women in the lowest quartile of total fat, in common with those in the lowest quartile of saturated fatty acids, were found to have higher intakes of fibre (P < 0.005), vitamin C (P < 0.01), folate (P < 0.005) and vitamin B6 (P < 0.05) while their intakes of vitamin A were lower (P = 0.01). Most (76%) of the differences in sugars intake between women of low and high total fat consumption were accounted for by added sugars, particularly non-fat containing confectionery/drink food sources where median daily intake values were 15 g vs 7 g sugars (P = 0.05) respectively. The finding that at best only 62% of the women had total fat and saturated fatty acids intake in similar quartiles, together with the differences that emerged in their food intake patterns, indicate that the goals for these nutrients may be separately achieved.

CONCLUSION

Existing dietary data can be useful for the formulation of specific food based dietary guidelines and diets higher in sugar are not necessarily more dilute in micronutrients.

Endothelin A receptor antagonism by PD 156707 does not reduce infarct size after coronary artery occlusion/reperfusion in pigs

Episodes of myocardial ischemia are associated with increases in cardiac venous plasma endothelin (ET) concentrations, suggesting that ET may play a role in the development of myocardial infarction. The purpose of this study was to determine if selective blockade of ET(A) receptors by PD 156707 reduces infarct size caused by coronary artery occlusion and reperfusion in pentobarbital-anesthetized micropigs. A PD 156707 dose which selectively blocks the ET(A)-mediated vasopressor response, but not the ET(B)-mediated vasodepressor response to i.v. ET-1 challenges (0.3 nmol/kg), was established in dose ranging studies in anesthetized micropigs. In myocardial infarction studies, micropigs received either saline vehicle (n = 7) or PD 156707 (n = 8) at a loading dose of 10 mg/kg/1 hr, followed by a maintenance dose of 7 mg/kg/hr. Coinciding with the start of the maintenance dose, the left anterior descending coronary artery was occluded for 1 hr followed by 3 hr of reperfusion. PD 156707 caused a significant (29 mm Hg) decrease in arterial blood pressure before occlusion. PD 156707 had no effect on infarct size (61.1 +/- 5.6% of the region at risk in the PD 156707 treatment group vs. 70.1 +/- 3.9% in the control group). These results suggest that ET(A) receptor activation does not substantially contribute to coronary artery occlusion/reperfusion-induced myocardial infarction.

Endothelin and PDGF enhance arachidonic acid release and DNA synthesis in vascular smooth muscle cells

Intracellular signaling mechanisms affected by endothelin (ET), a hypertrophic agonist, and platelet-derived growth factor (PDGF)-BB, a proliferative agonist, in vascular smooth muscle cells were examined. PDGF-BB was a potent mitogen compared with untreated cultures, stimulating both [3H]thymidine incorporation and cell number. In contrast, ET was a poor mitogen, enhancing [3H]thymidine incorporation but not cell number. Simultaneous ET and PDGF-BB treatment was significantly more effective than either agonist alone at stimulating both [3H]thymidine uptake and cell number. Although either ET or PDGF-BB alone stimulated arachidonic acid release, phosphoinositide hydrolysis, protein kinase C activation, PDGF receptor phosphorylation, and mitogen-activated protein kinase activity, of these effectors, only arachidonic acid release was further enhanced by simultaneous ET and PDGF-BB treatment. These results link proliferative and hypertrophic signal transduction pathways in these cells and suggest that arachidonic acid or its metabolites mediate the observed effects of ET on PDGF-BB-stimulated vascular smooth muscle cell proliferation.

Comparison of body composition measured by total body potassium and infrared interactance

OBJECTIVE

The purpose of this study was to find how closely a near infrared instrument (IRI), Futrex 5000, would compare to whole body counting (WBC) of potassium-40 (40K) in assessing body composition.

DESIGN

We measured lean body mass (LBM) and percent total body fat (PCF) in 177 males and 27 females by total body potassium (TBK) and by infrared interactance (IRI). TBK was assessed by 2 pi whole body counter (WBC) and IRI by Futrex (F) instrument. These subjects were measured for TBK and for IRI within 1 week of each other.

RESULT

A large mean difference (p < or = 0.001) was found between the results using the two instruments: IRI data for LBM were higher and PCF lower compared to TBK.

CONCLUSION

As shown by repeated TBK measurements over a 22-year period in these same volunteers, this technique is reliable. The IRI assessments did not come to a close fit with TBK.

Structure-activity relationships of the potent combined endothelin-A/endothelin-B receptor antagonist Ac-DDip16-Leu-Asp-Ile-Ile-Trp21: development of endothelin-B receptor selective antagonists

The endothelins (ETs) are a family of bicyclic 21-amino acid-containing peptides that are highly potent and prolonged vasoconstrictors. The discovery of potent ET antagonists will facilitate the understanding of the physiological and/or pathophysiological role of ET. Structure-activity studies have revealed the importance of the C-terminal hexapeptide (residues 16-21) of ET (His16-Leu17-Asp18-Ile19-Ile20-Trp21) to the development of potent antagonists at both receptor subtypes (ETA and ETB). In particular, it has been shown that Ac-DDip16-Leu-Asp-Ile-Ile-Trp21 (Dip = 3,3-diphenylalanine) has low nanomolar affinity for the two endothelin receptor subtypes and is a functional antagonist of ET activity, both in vitro and in vivo at both receptors. Herein, we will describe the structure-activity relationships of Ac-DDip16-Leu-Asp-Ile-Ile-Trp21 (PD 142893) with a particular emphasis on modifications that lead to enhanced receptor affinity and/or individual receptor subtype selectivity. In particular, we will demonstrate how we utilized PD 142893 to develop ETB receptor selective ligands and the pharmacological differences that exist between species ETB receptors with respect to their affinity for C-terminal hexapeptide antagonists.

Pharmacological characterization of PD 156707, an orally active ETA receptor antagonist

We describe the pharmacological characteristics of PD 156707 (sodium 2-benzo[1,3]dioxol-5-yl-4-(4-methoxy-phenyl)-4-oxo-3-(3,4,5- trimethoxy-benzyl)-but-2-enoate), a potent, orally active, nonpeptide antagonist of the endothelin A (ETA) receptor subtype. PD 156707 was designed on the basis of a compound identified by screening the Parke-Davis chemical library. PD 156707 is highly selective for the ETA receptor (ETAR) and inhibits the binding of [125I]-ET-1 to cloned human ETAR and ETBR with Ki values of 0.17 and 133.8 nM, respectively. PD 156707 antagonizes ET-1-stimulated phosphoinositide hydrolysis in Ltk- cells expressing cloned human ETAR with an IC50 value of 2.4 nM. PD 156707 inhibits vasoconstriction in isolated blood vessels mediated by ETAR (rabbit femoral artery) and ETBR (rabbit pulmonary artery) with pA2 values of 7.5 and 4.7, respectively. PD 156707 administered orally to rats blocked subsequent ETAR-mediated pressor responses in vivo but had no effect on ETBR-mediated dilator responses. As a potent and orally active ETA-selective antagonist, PD 156707 will be useful in defining the physiological and pathological roles of ETAR.

Pharmacological differences between rat and human endothelin B receptors

Cloned rat and human endothelin-B receptors (ETBR) were utilized to determine if there are significant pharmacological differences between highly homologous ETBR from different species. Recombinant rat and human ETBR were expressed in CHO-K1 cells, and radioligand binding studies were carried out with [125I]-ET-3 to determine the affinities of various ET receptor agonists and antagonists for rat and human ETBR. These receptors had similar affinities for a number of ETBR agonists (ET-1, ET-3, S6C, BQ 3020) and antagonists (Ro 47-0203, PD 142893). However, several peptide (PD 147452, PD 151583, BQ 788) and non-peptide (PD 156707, SB 209670) antagonists had different affinities for rat and human ETBR, with differences in Ki values between species ranging from 4.1- to 53.4-fold. The ETBR-selective agonist IRL 1620 also had a 5.7-fold higher affinity for rat ETBR than human ETBR. Thus despite their high degree of homology, rat and human ETBR show significant pharmacological differences with respect to both antagonist and agonist binding.

The effect of folate and cobalamin on osteoarthritic hands

OBJECTIVE

Historically diet and arthritis have been cause/effect associated but the idea is controversial with little evidence that specific diet components are effective treatment. This controlled, double-blinded, crossover study reports the effect of folate and cobalamin supplements in 26 humans diagnosed for an average 5.7 years with idiopathic osteoarthritis of the hands who had been medicated by prescribed nonsteroidal anti-inflammatory drugs (NSAID).

METHODS

Subjects entered the study after a 10-day washout period from use of all anti-arthritis drugs, vitamins, and minerals. They were randomly allocated to consume daily 6400 micrograms folate or 6400 micrograms folate plus 20 micrograms cobalamin or lactose placebo each for 2 months within self-selected diets. Pain was to be medicated by acetaminophen as needed, and at the end of each phase they returned for assessment and dispensing of the next treatment. Serum folate and cobalamin, red blood cell folate, blood smears, diet records, standard rheumatology assessment and hand grip measurements were reviewed and statistically analyzed.

RESULTS

For all subjects mean right and left hand grip values were higher with combined cobalamin-folate ingestion than with other "vitamin" supplements and were equivalent to NSAID use. Number of tender hand joints were greater with use of NSAID than with use of cobalamin-folate. Side effects with the vitamin combination were none; side effects of NSAID are many, and the cost of vitamins and acetaminophen also is lower.

CONCLUSION

The limited number of subjects in this study demonstrates that ingestion of a prescribed cobalamin-folate supplement and acetaminophen as needed resulted in positive outcomes.

Experience with Enterobacter bacteraemia in a Dublin teaching hospital

In a review of Enterobacter bacteraemia in a 600-bedded teaching hospital, 22 episodes were identified in 20 patients over a 2-year period. An evaluation of risk factors suggested an association between Enterobacter infection and the presence of central venous catheters or use of H-2 receptor antagonists. These factors together with previous exposure of the patient to gentamicin, and prolonged stay in the intensive care unit, increased the likelihood of gentamicin-resistant Enterobacter bacteraemia. This finding has implications for the choice of antibiotic regimen in the empirical treatment of suspected Gram-negative septicaemia.

Comparison of different measurements of lean body mass in normal individuals and in chronic peritoneal dialysis patients

To evaluate different methods of measuring lean body mass (LBM) in chronic peritoneal dialysis (CPD) patients, we first made comparisons in seven normal subjects. Seven methods (total body potassium [TBK] counting, bioelectrical impedance with calculations according to Segal and Deurenberg, near-infrared interactance with and without exercise level included as a variable, anthropometric measurements, and creatinine kinetics) were compared with the standard method of underwater weighing (UW) for measuring LBM. Significant correlations with LBM measured by UW (r > 0.938) were found with LBM measured by all other methods. Compared with UW, the best result in normals was found with TBK as it had high r values, small y-intercepts, and slopes of regression lines close to unity in both measurements of LBM and %LBM; in addition, fat-free mass index by TBK best approximated that by UW and TBK had the lowest mean prediction error with UW. In 11 patients on CPD, LBM was measured by all the above methods except UW. Significant correlations of all methods with LBM measured by TBK used as the reference standard were noted (all r > 0.76) in the CPD population. The LBM measured by creatinine kinetics correlated best (by kilograms or percentage of body weight [%BW]) with LBM from TBK compared with the other methods in which values tended to be higher. The fat-free mass index by creatinine output was nearest to the fat-free mass index by TBK. The root mean square prediction error was lowest between LBM by creatinine output and that by TBK. The findings support the concept of measuring creatinine outputs in CPD patients for estimates of LBM as an index of nutritional status as well as for creatinine clearances as an index of adequacy. Total body potassium and creatinine output measurements of LBM reflect the LBM at normal body fluid volumes ("dry weight") and may be better indices of nutrition in dialysis patients than the other techniques, which include excess fluid in the LBM.

Indices of obesity and body fat distribution in arteriographically defined coronary artery disease in men

Anthropometric measurements descriptive of obesity, body fat distribution and body build were made in 186 males undergoing diagnostic coronary arteriography. Using stepwise multiple logistic regression analysis, two indices of body fat distribution were independently associated with coronary disease, while the widely used indices of obesity, namely body mass index and percentage body fat, were not. A significant association with disease was found for the ratio of waist to thigh circumferences (waist/thigh ratio), which emerged in the first step of the multivariate model (p < 0.005). The ratio of waist to hip circumferences (waist/hip ratio), a widely used index of body fat distribution, was found to have a negative association with disease (p < 0.05). This study suggests that use of body fat distribution indices may assist in the assessment of the risk factor profile of cardiac patients.

ETA and ETB receptors coexist on rabbit pulmonary artery vascular smooth muscle mediating contraction

The possibility that both ETA and ETB endothelin receptor subtypes could mediate contractile activity in the same tissue was investigated in isolated, endothelium denuded rabbit pulmonary arteries. The ETB selective agonist, sarafotoxin 6c (S6c), produced potent contractile activity, equal to the non-selective ETA and ETB receptor agonist endothelin-1 (ET-1), indicating a contractile role for ETB receptors in this tissue. In addition BQ-123 (10.0 microM), the ETA selective antagonist, was only partially effective in blocking ET-1 induced contractions further indicating a contractile role for ETB receptors. However, the partial blockade by BQ-123 suggested a possible contractile role for ETA receptors. To address this possibility, ETB receptors were desensitized with a 30 minute pretreatment of S6c (0.01 microM). Under these conditions, we were able to demonstrate full ET-1 contractile activity that was now sensitive to blockade by BQ-123. The coexistence of both ETA and ETB receptors was confirmed through receptor binding experiments indicating 40/60 ratio, respectively. We conclude that 1) both ETA and ETB receptors coexist on vascular smooth muscle of rabbit pulmonary artery, 2) activation of either receptors subtype results in contraction, and 3) prolong activation of the ETB receptor subtype produces tachyphylaxis preventing further activation by S6c or ET-1.

Truncated analogues of endothelin and sarafotoxin are selective for the ETB receptor subtype

The sarafotoxins (SRTXs) are a family of 21-amino acid bicyclic peptides that are structurally similar to the potent vasoconstrictors, the endothelins (ETs). SRTX-6c exhibits high selectivity for the ETB receptor subtype over the ETA subtype. This selectivity may be a result of a modification at positions 9 or 13, which are Glu9 and Asn13 in SRTX-6c and Lys9 and Tyr13 in ET-1. The truncated linear endothelin [Ala11,15]ET-18-21 was also on ETB receptor-selective ligand with 6-nM binding affinity. Therefore, a series of truncated endothelin/sarafotoxin (8-21) hybrid analogues were prepared, varying the amino acid at residues 9 and/or 13. These peptides were assayed for binding in tissues selectively expressing either the ETA or the ETB receptor subtypes. All linear analogues showed poor ETA binding, while ETB affinity was sequence dependent. Monocyclic 11-15 disulfide-containing analogues failed to bind to either ETA or ETB receptors at concentrations of up to 10 microM.

In vitro and in vivo studies with a series of hexapeptide endothelin antagonists

The effects of different amino acids incorporated into the 16 and 17 positions of the C-terminal hexapeptide of ET-1 were examined. Structure-activity relationships (SAR) of the ET receptor antagonists PD 142893 [Ac-(D-Dip16-L-Leu17-L-Asp-L-Ile-L-Ile-L-Trp) (D-Dip = 3,3-D-diphenylalanine)] and PD 145065 [Ac-(D-Bhg16-L-Leu17-L-Asp-L-Ile-L-Ile-L-Trp) (D-Bhg = 5H-dibenzyl[a,d]cycloheptene-10,11-dihydro-glycine)] uncovered certain requirements for high potency. The disodium salt of PD 145065 has 4.0 and 15 nM binding affinity (IC50 values) for the ETA (rabbit renal artery vascular smooth-muscle cells) and ETB receptor (rat cerebellum), respectively. The compound is also an antagonist of ET-1- and SRTX-6c-stimulated vasoconstrictor activity, with pA2 values of 6.9 (rabbit femoral artery, ETA assay) and 7.1 (rabbit pulmonary artery, ETB assay). The tripeptidic ETA antagonist FR 139317 was found to be less active in the rabbit femoral artery, with a pA2 value of 6.0, and inactive in the rabbit pulmonary artery. Substitution of acidic and basic residues at position 17 in PD 142893 and PD 145065 indicates differences in selectivity. Incorporation of bulky non-natural amino acids at position 16 has led to potent nonselective analogues, including Ac-D-Bheg16-L-Leu-L-Asp-L-Ile-L-Ile-L-Trp [D-Bheg (5H-dibenzo[a,d]cycloheptene glycine)]. The in vivo effects of single-bolus doses of selected ET antagonists on depressor and pressor responses to ET-1 in anesthetized ganglion-blocked rats were evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging in humans: a continuous 20-year study of physiologic and dietary parameters

The old adage, "You are what you eat," is not always reliable, as demonstrated in this mixed-longitudinal study of men that began in 1969. Mean values of percent body fat, total body potassium (TBK), and total serum cholesterol (SCHOL) did not show changes that correlated with any studied nutrient from repeated 4-day diet records. Mean blood pressure increased with increased body weight as age increased. High-density lipoprotein cholesterol decreased when polyunsaturated fat intake increased. The men had decreased mean height, TBK and increase in percent body fat as age increased. Food energy intake decreased equally from carbohydrates, protein and fat as age increased. Large standard deviations of mean values of measured parameters document heterogeneity of these subjects. A subset of 144 male cohorts was studied serially for 20 years in time-age, cross-sectional and longitudinal series. As they aged, height and TBK decreased (p < or = 0.05), percent body fat and blood pressure increased (p < or = 0.04) and SCHOL had no significant change. Intake of all nutrients decreased significantly (p < or = 0.03) longitudinally and with time, showing a time effect.

Effects of cholesterol and fat modification of self-selected diets on serum lipids and their specific fatty acids in normocholesterolemic and hypercholesterolemic humans

A 6-month crossover diet plan was employed to study the effects on human serum lipids of adding margarine or butter to otherwise self-selected diets that included two eggs daily. Two groups of subjects were studied: 51 free-living normocholesterolemic and 20 hypercholesterolemic (greater than 240 mg dl). Four-day diet records in each interval showed that subjects ate about 16% of total dietary fat as either butter or margarine. Blood samples taken every 6 weeks showed variable mean serum total cholesterol (SCHOL), high-density-lipoprotein cholesterol (HDL-C), and serum triglycerides (STG). The normocholesterolemic subjects who ate butter first had by 24 weeks mean SCHOL values equal to their entry values; those who ate margarine first had increased SCHOL values throughout the study. By the end of the study, the hypercholesterolemic subjects showed either no change or a slight decrease in both SCHOL and HDL-C values. Specific fatty acids were distributed differently in the serum fractions of triacylglycerol (TGFA), cholesteryl esters (CEFA), and phospholipids (PLFA). These distributions remained constant in both normocholesterolemic and hypercholesterolemic subjects regardless of the type and amount of fat consumed.

Melanotic schwannoma of the sympathetic ganglia: pathological and clinical characteristics

Reports of melanin-producing tumors of Schwann cell origin are extremely rare. Reports of only 9 such tumors arising from sympathetic ganglia have been published previously. Two new cases of melanotic schwannoma of sympathetic ganglia are reported. The pathological and clinical characteristics of these unusual melanotic tumors are discussed.

Total body potassium in aging humans: a longitudinal study

Total body potassium (TBK) data calculated from longitudinal measurements over 18 y of 40K by whole-body counting of 564 male and 61 female healthy humans in a 2-pi liquid scintillation counter show little change in females younger than 50 y compared with males of those ages. Males show less TBK from 41 y onward as they age, with most rapid rate of loss between 41 and 60 y. Females have a rapid loss of TBK when they are older than 60 y; the loss is at a greater rate than that of males. Percent total body fat calculated from total body weight and lean body mass (LBM) derived from TBK document greater adiposity in females at all ages except ages 51-60 y when females are similar to males in change in percent fat per year per centimeter.

Serum lipids and eggs

This study shows the variability of response of serum cholesterol to whole food dietary cholesterol eaten by free-living people. Divided into two groups in a crossover design, normolipemic, healthy volunteers in Group A showed statistically significant increases in mean serum cholesterol after eating three eggs daily for 10 weeks (p less than or equal to .01) and a significant decrease within 2 weeks of crossover to eating no eggs (p less than or equal to .03). Group B exhibited a significant decrease in mean serum cholesterol after eating no eggs for 12 weeks (p less than or equal to .02) but, after crossing over to eating 3 eggs daily for 10 weeks, showed no longitudinally significant increases. Only Group A showed statistically significant changes in mean high-density-lipoprotein cholesterol, i.e., an increase at the end of 12 weeks of eating three eggs daily (p less than or equal to .001). Mean serum triglycerides showed no significant change.

Hemorrhagic acalculous cholecystitis causing acute pancreatitis after trauma

Hemobilia is an uncommonly recognized entity and postoperative acute acalculous cholecystitis is an uncommon clinical entity. Hemorrhagic acalculous cholecystitis causing pancreatitis has apparently not been reported before. We report the case of a multiple trauma victim who, several weeks after his initial injuries, developed acute pancreatitis secondary to hemobilia caused by postoperative hemorrhagic acalculous cholecystitis.

Eggs, serum lipids, emotional stress, and blood pressure in medical students

Emotional stress that occurred as a result of anticipation and participation in final exams did not change mean serum total cholesterol or high density lipoprotein cholesterol significantly in 26 male students who had eaten two eggs daily while maintaining a controlled diet for 12 wk. These same men continued to maintain a controlled diet but abstained from eating eggs for 12 wk which resulted in a statistically significant lower total cholesterol level at the end of 6 wk and on the day of final exams at the end of 12 wk. Mean values for high-density lipoprotein cholesterol in abstainers were significantly reduced at the end of 6 wk, but did not change further by 12 wk. Mean serum triglycerides values were variable. Blood pressures were not changed significantly.

Dietary "meats" and serum lipids

The mean values for serum total cholesterol for 47 males, aged 32 to 62 yr who, over a 10 1/2 month study ate, within a self-selected diet, beef as the only meat for 3 months, poultry and fish for 3 months, and pork for 3 months showed no statistically significant difference, whereas 17 of 29 females of the same age who participated in the same study had borderline statistically significant differences in mean values (p less than 0.055). When data from all subjects were considered together, no statistically significant changes in mean serum total cholesterol or serum triglycerides were noted, but there were significant changes in mean high-density lipoprotein cholesterol values, both upward and downward. The important results of this study are documentary to the lack of influence of "meat" and its fat on effecting a significant change in serum total cholesterol within a self-selected diet.

Serum lipids in humans fed diets containing beef or fish and poultry

One half of a group of 129 men and women (74 men and 55 women), in a cross-over design at, within a self-selected diet, one egg and at least 5 oz of beef daily for 3 months while the other half at one egg and at least 5 oz of poultry and fish daily. Then they reversed their diets for 3 months. Blood samples were drawn by venipuncture before the study started and at the end of the 3 and 6 months, for analyses of serum total cholesterol, triglycerides, and high density lipoprotein cholesterol. No statistically significant changes were found in serum lipids in men. In women serum triglycerides but not other serum lipids were significantly higher when poultry and fish had been ingested.

Effects of medroxyprogesterone acetate and caloric restriction on the distribution of serum and liver lipids and proteins in female rats

The effects of a large dose (2 mg/100 g body weight) of medroxyprogesterone acetate (MPA), restricted feeding (50% of normal intake) and their interaction were investigated on the serum and liver lipid and protein distribution in female rats. MPA increased serum cholesterol and triglyceride levels in rats on ad libitum food intake without having any effect in the animals on restricted diet. There was no statistical difference in the total serum protein or albumin levels among the groups. The serum levels of alpha and gamma globulin were significantly lower in the underfed rats. MPA increased the concentration of gamma globulin in well nourished rats but interacted with dietary restriction to further reduce the level of this protein in the undernourished animals. There was no difference in the levels of hepatic phospholipids or free cholesterol among groups, However, cholesterol ester and triglyceride levels in liver were significantly elevated in the MPA-treated group fed ad libitum. A similar increase was not found in underfed rats. This study indicates that MPA exerts significant effects on the distribution of serum and hepatic lipids and serum globulin levels and that the effects are dependent upon the nutritional status of the subject.

Total body potassium--a guide to nutritional health in patients undergoing continuous ambulatory peritoneal dialysis

Nutritional status in patients undergoing continuous ambulatory peritoneal dialysis was estimated by serial simultaneous measurements (3 to 6 months) of total body potassium, weight, serum, albumin, total serum globulins and IgG, IgA, IgM, total iron binding capacity, and hematocrit. Correlations were performed between the changes per month in these measurements and with episodes of peritonitis per month. Changes per month in serum albumin and total iron binding capacity correlated with total body potassium. Serum immunoglobulins fell with time on continuous ambulatory peritoneal dialysis but there was no correlation with the other measurements. Changes in total body potassium per month correlated negatively with episodes of peritonitis per month. Of these measured parameters only the change in total body potassium per month reflected long-term clinical consequences of peritonitis. The studies suggest that lower rates of infection, hopefully now possible with solutions in plastic bags, will prevent catabolism.

Effect of dietary egg on human serum cholesterol and triglycerides

One hundred sixteen male volunteers between the ages of 32 and 62 years (mean age 46) consumed two whole fresh eggs daily in their customary diets for 3 months and also eliminated eggs for 3 months before or after eating eggs. The men had had normal-range serum cholesterol and triglycerides for the past 7 years. Four-day food records kept by them in each experimental period were assessed for nutrient intake. A Latin square design allowed analyses for season and sequential effects on serum lipids. The serum cholesterol and triglyceride levels at the end of 6 months were compared with their initial levels on customary free choice diets as well as their levels after the first 3 months of study. No significant increase in mean serum cholesterol was found nor was there a significant association of dietary cholesterol intake with either serum cholesterol or triglyceride.