Risk factors for hypertension in Kimberley Aborigines

OBJECTIVE

To determine physical, biochemical and lifestyle factors associated with high blood pressure among Aborigines in the Kimberley region.

DESIGN

Blood pressure and electrocardiographic (ECG) abnormalities in an age and sex stratified random sample of the Aboriginal population were related to other observations and measurements made at the same time specifically for the purpose of these comparisons.

SETTING

A field study in which subjects were interviewed and measurements made mostly in community clinics.

PARTICIPANTS

All 249 men and 241 women from the prevalence study were included although only complete data sets for the various comparisons were analysed.

INTERVENTIONS

A sample of venous blood was obtained in addition to physical measurements and information at interview.

MAIN OUTCOME MEASURES

Statistical analysis of the relationships between blood pressure or hypertension and alcohol consumption, plasma gamma-glutamyl transpeptidase (GGT) activity, use of tobacco, body mass index (BMI, kg/m2) and non-fasted plasma cholesterol level. Hypertension was defined as systolic blood pressure of 160 mmHg or greater or diastolic blood pressure of 95 mmHg or greater.

RESULTS

High blood pressure in Aboriginal men below 30 years was associated both with current drinking status and with circulating GGT level. There was a positive association of diastolic hypertension with consumption of alcohol in middle aged men (30 to 49 years) and in older women. Drinking was highly prevalent among men, especially below 30 years, but was less prevalent among women. Both systolic and diastolic blood pressure were positively related to BMI across the population but obesity (BMI greater than or equal to 30 kg/m2) was highly prevalent only among middle-aged women. Both systolic and diastolic blood pressure were positively and strongly related to plasma cholesterol level independently of the latter's relationship to age and BMI.

CONCLUSION

The high prevalence of drinking among Aboriginal men and of obesity among Aboriginal women involves a risk of hypertension. The association between plasma cholesterol and blood pressure in Aboriginal men and women may be relevant to the demonstrated link between systolic hypertension and ischaemic heart disease.

Ca2+/calmodulin-dependent NO synthase type I: a biopteroflavoprotein with Ca2+/calmodulin-independent diaphorase and reductase activities

NO synthase (NOS; EC 1.14.23) catalyzes the conversion of L-arginine into L-citrulline and a guanylyl cyclase-activating factor (GAF) that is chemically identical with nitric oxide or a nitric oxide-releasing compound (NO). Similar to the other isozymes of NOS that have been characterized to date, the soluble and Ca2+/calmodulin-regulated type I from rat cerebellum (homodimer of 160-kDa subunits) is dependent on NADPH for catalytic activity. The enzyme also possesses NADPH diaphorase activity in the presence of the electron acceptor nitroblue tetrazolium (NBT). We investigated the requirements of NOS and its content of the proposed additional cofactors tetrahydrobiopterin (H4biopterin) and flavins, further characterized the NADPH diaphorase activity, and quantified the NADPH binding site(s). Purified NOS type I Ca2+/calmodulin-independently bound the [32P]2',3'-dialdehyde analogue of NADPH (dNADPH), which, at near Km concentrations during 3-min incubations was utilized as a substrate and at higher concentrations or after prolonged incubations and cross-linking inhibited NOS activity. The NADPH diaphorase activity was Ca2+/calmodulin-independent, required higher NADPH concentrations than NOS activity, and was affected by dNADPH to a lesser degree. Divalent cations interfered with the diaphorase assay. Per dimer, native NOS contained about 1 mol each of H4biopterin, FAD, and FMN, classifying it as a biopteroflavoprotein, and incorporated 1 mol of dNADPH. No dihydrobiopterin (H2biopterin), biopterin, or riboflavin was detected. These findings suggest that NOS may share cofactors between two identical subunits via high-affinity binding sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-high-pH buffer eluent. Changes in selectivity with the age of the stationary phase

The long-term reproducibility of the separation of basic drugs by high-performance liquid chromatography using a silica column with a methanol-high-pH eluent was examined. The relative capacity factors of specific tertiary amines changed systematically compared with the other drugs on storage of the columns for 1 year. The changes were enhanced on storing the column in mobile phase and were accelerated by prolonged washing with water. A comparison of freshly packed columns suggested that similar changes also occurred with the dry silica on storage. These effects may be a contributor to previously observed batch-to-batch differences in the silica.

Insulin stimulates accumulation and efflux of macromolecules in isolated nuclei from H35 hepatoma cells

This study used 10-nm gold particles with 5-7 insulin molecules attached (Au10-Ins) to investigate the site of interaction of insulin with the nuclear envelope during insulin uptake into intact isolated nuclei. Despite its size, and in the absence of ATP, Au10-Ins entered nuclei through the nuclear pore and associated with the heterochromatin. Because Au10-Ins is essentially gold-bovine serum albumin (Au-BSA) with a few insulin molecules attached, the effect of insulin and other growth factors on the nuclear accumulation of BSA coupled to 10-, 15-, and 24-nm-diam colloidal gold particles (Au10-BSA, Au15-BSA, and Au24-BSA) was determined. The Au-BSA complexes were excluded from nuclei in the absence of insulin. Insulin (0.5-100 ng/ml) caused a dose-dependent accumulation of Au10-BSA in the nucleus. The nuclear membrane was shown to be intact by several criteria, therefore, accumulation of Au-BSA occurred via the nuclear pore and was not due to leakage across or through the membrane. Uptake of 15- and 24-nm Au-BSA molecules was not affected by insulin, suggesting the hormone had a limited effect in increasing the functional diameter of the nuclear pores. Glucagon, epidermal growth factor, platelet-derived growth factor, insulinlike growth factor I, and insulin A or B chains did not stimulate the accumulation of Au10-BSA. The insulin-stimulated accumulation of Au10-BSA was blocked by concanavalin A, mimicked by wheat-germ agglutinin, and did not require ATP. The Au10-BSA in the nucleus was associated with heterochromatin, suggesting it bound to a nuclear element.(ABSTRACT TRUNCATED AT 250 WORDS)

Tracheal collapse in a Holstein heifer

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Monoclonal antibodies: harnessing the potential

Antibody molecules help fulfil the mandate of the mammalian immune system to discriminate between the body's own proteins and the foreign antigens of infectious agents. The exquisite specificity they exhibit for their target molecules has lent itself to exploitation both in the laboratory and clinical medicine. Nevertheless, the early reliance on polyclonal antisera as a source of antibodies, has highlighted problems of homogeneity and reproducibility between immunizations. The advent of monoclonal antibodies displaying a single predefined specificity has, therefore, revolutionised many areas of the biomedical sciences. Eighteen years after their first description, it is, however, pertinent to ask whether monoclonal antibodies have yet fulfilled their true potential.

Insulin, insulin-like growth factors and glucose transporters: temporal patterns of gene expression in early murine and bovine embryos

mRNA phenotyping by the reverse transcription-polymerase chain reaction (RT-PCR) method was used to compare the patterns of expression of insulin and insulin-like growth factor (IGF) ligand and receptor genes in preimplantation bovine embryos with those established previously for preimplantation murine embryos. In the early bovine embryo, transcripts for IGF-I, IGF-II and mRNAs encoding receptors for insulin, IGF-I and IGF-II were all detectable at all embryo stages from the 1-cell zygote to the blastocyst. In the mouse, IGF-II ligand and receptor mRNAs were not expressed until the 2-cell stage, and the insulin and IGF-I receptor mRNAs were not detectable until the 8-cell stage. Since transcriptional activation of the embryonic genome occurs at the 8- to 16-cell stage in the bovine embryo and at the 2-cell stage in the murine embryo, it is suggested that these transcripts are products of both the maternal and embryonic genomes in the bovine embryo whereas in the mouse they are present only after activation of the embryonic genome. Transcripts for insulin were not detected in preimplantation embryos of either species. Colloidal-gold immunocytochemistry with antibodies directed against the insulin receptor, IGF-I receptor and IGF-I ligand has confirmed the presence of these molecules in bovine blastocysts. RT-PCR and indirect immunofluorescence procedures demonstrated that the glucose transporter (GLUT) isoform 1 is present in murine embryos from the oocyte to blastocyst stage whereas GLUT 2 expression begins at the 8-cell stage.

Value of radiograph audit in an accident service department

In our accident service department all trauma radiographs are reported acutely and those misinterpreted by the casualty officers are presented at the daily clinicoradiological conference. We have reviewed this practice over a 6-month period. From over 25,000 patients attending the accident service, 16,246 radiographs were requested and reported. Of these, 456 (2.8 per cent) were considered to have been potentially misinterpreted. The errors included 167 (1 per cent) missed fractures, 55 (0.3 per cent) suspected fractures and 72 (0.4 per cent) false-positive diagnoses of fracture. Subsequently, 114 (0.7 per cent) patients required recall for treatment or further imaging. Incorrect diagnoses were seen most frequently in the more commonly injured anatomical sites--the ankle, wrist, foot, elbow and hand. However, the incidence of misinterpretation was highest in examination of the fingers, especially in children. We believe that these low figures are principally the result of involving both orthopaedic surgeons and radiologists at the formal daily conference. We regard our system of audit as beneficial to patients' care and anticipate reduced litigation which may offset the increased cost of audit.

Subcellular distribution of the alpha subunit(s) of Gi: visualization by immunofluorescent and immunogold labeling

The subcellular distribution of the alpha subunit(s) of Gi has an obvious bearing on the ability of this protein to interact with receptors and targets and on its potential to serve in still unexplored capacities. In this study, we have examined the distribution of Gi alpha by means of light and electron microscopy. The cells employed were mouse 3T3 fibroblasts, normal rat kidney fibroblasts, rat C6 glioma cells, human umbilical vein endothelial cells, and human 293 kidney fibroblasts. By indirect immunofluorescence, two patterns of Gi alpha were evident. The more prominent was that associated with phase-dense, cytoplasmic structures exhibiting a tubule-like morphology. A similar distribution was noted for mitochondria, indicating attachment to a subset of microtubules. The second pattern appeared as a diffuse, particulate fluorescence associated with the plasma membrane. By immunogold labeling and electron microscopy, two populations of Gi alpha were again evident. In this instance, labeling of the plasma membrane was the more prominent. Gold particles were most often evenly distributed along the plasma membrane and were concentrated along microspikes. The second, less abundant population of Gi alpha represented the subunit (or fragments) within lysosomes. Specificity in immunolabeling was confirmed in all instances by immunotransfer blotting, the use of antibodies differing in specificities for epitopes within Gi alpha, the absence of labeling with preimmune sera, and the decrease in labeling after preincubation of antisera with appropriate peptides. These results support the proposal that several populations of Gi alpha exist: those evident within the cytoplasm by immunofluorescence, those present at the plasma membrane, and those evident within lysosomes by immunogold labeling.

Effects of long-term dietary cadmium chloride on tissue, milk, and urine mineral concentrations of lactating dairy cows

The effects of long-term consumption of 1 and 5 ppm of Cd on Cd, Cu, Fe, and Zn concentrations in milk and a variety of tissues of first-lactation dairy cows was investigated. Thirty-six Holstein heifers were allocated to three groups and fed similar diets differing only in the concentration of Cd (.25, 1, and 5 ppm) for a 394-d period before calving. One- and 5-ppm Cd concentrations were achieved using CdCl2. Liver, kidney cortex, and muscle were biopsied from one-half of the heifers of each group before Cd supplementation and again from the same heifers within 5 d after parturition. Colostrum and milk were sampled throughout the 150 d of lactation. Urine was sampled after an average of 450 d of Cd exposure. At slaughter (after an average of 554 d), 11 tissues were sampled from 12 cows representing all treatment groups. During the first 394 d, Cd accumulated in kidney and liver with increasing dietary concentrations of Cd but did not further increase by 554 d. However, by 554 d Cd had also accumulated in the adrenal glands, ovaries, spleen, and uteri of cows consuming 5 ppm of Cd. Dietary Cd did not influence the concentration of Cd, Cu, Fe, or Zn in colostrum or milk. However, urine pH, Zn, and K were lower in cows consuming 5 ppm of Cd. Liver Cu was reduced by 1 and 5 ppm of Cd at both 394 and 554 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dietary cadmium chloride throughout gestation on blood and tissue metabolites of primigravid and neonatal dairy cattle

Thirty-six postpubertal Holstein heifers were allocated to three groups and fed the same diet, which differed only in the concentration of Cd: control group (.25 ppm of Cd), low-Cd group (1 ppm of Cd), and high-Cd group (5 ppm of Cd). Cadmium was supplemented to the low-Cd and high-Cd groups using CdCl2. Liver, kidney cortex, and abdominal muscle were biopsied for mineral analysis from one-half of the heifers of each group before Cd supplementation and again from the same animals within 5 d after parturition, 394 d later. Blood, liver, and muscle were collected from each calf within 5 h after birth. In the dam, 5 ppm of dietary Cd caused a 62-, 27-, and 4-fold increase in Cd of the kidney, liver, and muscle, respectively; kidney Zn and Fe increased (76%) and decreased (33%), respectively, whereas the serum Cu was reduced (31%). Liver Cu was reduced to 40 and 17% by dietary Cd of 1 and 5 ppm, respectively, in the dams. Calves from dams consuming 5 ppm of Cd had a 29 and 43% reduction in liver Cu and Zn, respectively. In these same calves, packed cell volume, hemoglobin concentration, and serum Cu were decreased by 17, 18, and 25%, respectively, whereas serum Zn was increased (55%). Serum sodium and potassium were reduced by 4 and 13%, respectively, and blood urea nitrogen was increased by 63% in calves from dams consuming 5 ppm of Cd. Feeding primigravid dairy cattle up to 5 ppm of Cd as CdCl2 throughout gestation did not influence the concentration of Cd in the neonate but caused reductions in liver Cu and Zn; teratogenesis was not apparent.

Dietary fish oil administration retards the development of hypertension and influences vascular neuroeffector function in the stroke prone spontaneously hypertensive rat (SHRSP)

An influence of fish oils (rich in eicosapentaenoic acid, EPA) in modulating (a) the development of hypertension in the stroke prone spontaneously hypertensive rat (SHRSP) and (b) vascular neuroeffector mechanisms in the SHRSP was explored. Rats (SHRSP) were placed on a series of diets for a period of 13 weeks from 4 weeks of age. The fatty acid composition of the diets was derived from fish oil, olive oil, safflower oil or beef fat. After 13 weeks, rats fed diets containing fish oil (at a total dietary fat level of either 5% or 15%) had mean blood pressures approximately 20-25 mmHg lower than other SHRSP rats maintained on diets containing either olive oil, safflower oil or beef fat. The dietary schedules providing fish oil depressed the contractile responses mediated by sympathetic nerve stimulation in the mesenteric vascular bed preparation. The results suggest that the n-3 polyunsaturated fatty acids retard the development of hypertension in the SHRSP rat and modulate the contractile responses of blood vessels mediated by sympathetic nerves in the isolated perfused mesenteric vascular bed preparation.

Tyrosine kinase-defective insulin receptors undergo insulin-induced microaggregation but do not concentrate in coated pits

Biologically active colloid-gold complexes were used to compare ligand-induced microaggregation, redistribution, and internalization of insulin receptors on Rat 1 fibroblasts expressing wild type (HIRc) or tyrosine kinase-defective (HIR A/K1018) human insulin receptors. Insulin-like growth factor I (IGF I) and alpha 2-macroglobulin receptors also were compared. On both cell types, all four unoccupied receptor types occurred predominantly as single receptors. Ligand binding caused receptor microaggregation. Microaggregation of wild type or kinase-defective insulin receptors or IGF I receptors was not different. alpha 2-Macroglobulin receptors formed larger microaggregates. Compared to wild type insulin or IGF I receptors, accumulation of kinase-defective insulin receptor microaggregates in endocytic structures was decreased, and the size of microaggregates in coated pits was significantly smaller. As a result, receptor-mediated internalization of gold-insulin by HIR A/K1018 cells was less than 6% of the cell-associated particles compared to approximately 60% of the particles in HIRc cells. On HIR A/K1018 cells, alpha 2-macroglobulin and IGF I were internalized via coated pits demonstrating that those structures were functional. These results suggest that: 1) ATP binding, receptor autophosphorylation, and activation of receptor kinase activity are not required for receptor microaggregation; 2) receptor microaggregation per se is not sufficient to cause ligand-induced receptor-mediated internalization or the biological effects of insulin; and 3) autophosphorylation of the beta-subunit or activation of the receptor kinase activity is required for the insulin-induced concentration of occupied receptors in coated pits.

The transverse plane deformity of structural scoliosis

An examination of the transverse plane aspect of deformed vertebrae from specimens of both human and animal scoliosis identified a consistent pattern of intravertebral deformity. In the animal model, dynamic bone growth studies illustrated bone drift in the opposite direction to the rotation of the scoliosis, suggesting that the bone growth in the transverse plane was attempting to correct rather than produce the deformity. The observed pattern of vertebral deformity can be explained in simple terms because it obeys the standard laws of bone growth and remodeling. This observed growth pattern is consistent only with the production of idiopathic scoliosis by the rotation of a primary lordosis.

Immunoelectron microscopic demonstration of insulin-stimulated translocation of glucose transporters to the plasma membrane of isolated rat adipocytes and masking of the carboxyl-terminal epitope of intracellular GLUT4

Polyclonal antibodies to the amino- or carboxyl-terminated peptide sequences of the GLUT4 transporter protein were used in immunoelectron microscopic studies to demonstrate the location and insulin-induced translocation of GLUT4 in intact isolated rat adipocytes. Labeling of untreated adipocytes with the amino-terminal antibody revealed 95% of GLUT4 was intracellular, associated with plasma membrane invaginations or vesicles contiguous with or within 75 nm of the cell membrane. Insulin treatment increased plasma membrane labeling approximately 13-fold, to 52% of the total transporters, and decreased intracellular labeling proportionately. In contrast, labeling of untreated adipocytes with the carboxyl-terminal antibody or with a monoclonal antibody (1F8) that binds to the carboxyl terminus of GLUT4 detected fewer transporters, only approximately 40% of which were intracellular. In insulin-treated cells, plasma membrane labeling increased approximately 20-fold, but the total number of labeled transporters also increased approximately 13-fold. The number of intracellular transporters was not changed. The insulin-induced increase in plasma membrane labeling was reversible. Thus, the vast majority of GLUT4 transporters in untreated adipocytes are intracellular in invaginations or vesicles attached or close to the plasma membrane. Insulin treatment causes translocation of transporters to the plasma membrane, which involves flow of transporters from invaginations to the cell surface and possible fusion of subplasma membrane vesicles with the plasma membrane. Differences in the labeling of intracellular transporters by peptide antibodies suggested the carboxyl-terminal epitope of intracellular transporters was masked. The unmasking of the carboxyl terminus during translocation to the plasma membrane may be part of the mechanism by which insulin stimulates glucose transport in rat adipocytes.

Effects of dietary sodium and fish oil on blood pressure development in stroke-prone spontaneously hypertensive rats

The postulated antihypertensive effect of dietary fish oil and the influence of dietary sodium on this effect were evaluated in young stroke-prone spontaneously hypertensive rats (SHRSP) by direct intra-arterial measurement of blood pressure. Weaning rats were fed synthetic diets containing olive oil or eicosapentaenoic acid-enriched fish oil (5% of dry weight) with normal (0.23%) or high (2.8%) sodium content. Catheters were implanted after 3 months for blood pressure measurement under resting conditions and to sample blood for catecholamine determinations. Effects of fish oil on vascular reactivity were assessed in the in situ blood-perfused mesentery. The overall observation, from a series of experiments, was that feeding diets containing 5% fish oil to young SHRSP resulted in a small but consistent suppression of the development of hypertension. This effect could be counteracted, however, by increasing dietary sodium intake. Observations after ganglion blockade indicate that the antihypertensive effect of fish oil is unlikely to result from a reduction in sympathetic vascular tone.

Cerebral oedema with coning in diabetic keto-acidosis. Report of 2 survivors

Two children presented with a first episode of diabetic ketoacidosis. Initially both patients made a good clinical and biochemical recovery, but suddenly developed neurological signs consistent with a diagnosis of tentorial herniation. Cranial computed tomography showed signs of cerebral oedema in both cases with evidence of uncal and tentorial herniation in 1 patient, which resolved after the appropriate treatment. The excellent neurological outcome emphasises the need for early recognition and treatment of sudden onset brain oedema in diabetic keto-acidosis.

Embryonic chicken lens cells cultured in reconstituted basement membrane: an experimental model to maintain the epithelial phenotype in culture

The action of a reconstituted basement membrane has been studied on primary cultures of embryonic lens cells. When a solution of this matrix (Matrigel) was included in the culture medium, a high percentage of cells maintained the epithelial phenotype, judged by electron microscopy criteria, in contrast to the differentiated state induced by serum. Complete matrix stimulated by 6-fold the incorporation of 3H-thymidine into the cells, while one of its defined components, laminin, only had a 2-fold stimulatory effect. Thus, the basement membrane may stimulate mitogenesis and play a role complementary to that of growth factors in development.

One hour in 1 ATA oxygen enhances rat alveolar macrophage chemiluminescence and fungal cytotoxicity

The purpose of this study was to determine if 100% O2 would enhance rat pulmonary alveolar macrophage (PAM) oxidative killing of conidia of the fungus Neurospora crassa. First, we found that incubation in 100% O2 had no effect on conidia viability in the absence of PAM. We obtained resident PAM from nonpretreated anesthetized male Sprague-Dawley rats by bronchoalveolar lavage. Compared with similar air exposures we found that 1 h in vitro exposure of PAM to 100% O2 (1.0 atmosphere absolute) increased their killing of opsonized phagocytized conidia by 52%, without altering phagocytosis. A reactive oxygen killing mechanism is suggested because 1) 100% O2 increased PAM chemiluminescence (CL) by 60% both at rest and during 1 h of phagocytosis, and 2) PAM in 100% O2 killed albino conidia (lacking free radical-quenching carotenoids) 2.9 times more readily than they killed wild-type conidia. Compared with air, 100% O2 delayed the PAM respiratory burst time to peak by 18% but did not alter the burst maximal acceleration. The latter and the similar 60% increase in PAM CL in 100% O2 both at rest and during 1 h of phagocytosis suggests a nonenzymatic O2 enhancement of the respiratory burst. Changed timing of burst events in 100% O2 suggests early O2 toxicity. We conclude that 1 h in 100% O2 increases PAM free radical production and fungicidal activity.

Identification of the NADPH-binding subunit of the respiratory burst oxidase

The respiratory burst oxidase is a multicomponent membrane-bound enzyme that uses NADPH to reduce oxygen to O2-. When oxidase-containing membranes from activated neutrophils are treated with 0.3 M KCl, the NADPH-binding component of the oxidase elutes from the membranes in an active form. Treatment of this eluate with [32P]NADPH dialdehyde labels an approximately 32-kDa protein that is absent from eluates obtained from normal resting membranes or from resting or activated membranes from patients with one form of chronic granulomatous disease. We propose that this approximately 32-kDa protein is the NADPH-binding component of the oxidase.

Respiratory burst oxidase and three of four oxidase-related polypeptides are associated with the cytoskeleton of human neutrophils

Resting and phorbol-activated human neutrophils were separated by treatment with Triton X-100 into detergent-extractable and cytoskeleton fractions. Respiratory burst oxidase activity was restricted entirely to the cytoskeleton. The cytoskeleton also contained approximately 15% of the neutrophil cytochrome b558, an oxidase-associated heme protein, as well as most of the oxidase-related cytosolic polypeptide p67phox. In contrast, the components of the oxidase-associated phosphoprotein family p47phox were found almost exclusively in the detergent extract, suggesting that p47phox is needed for oxidase activation but not for O2- production by the activated oxidase. Activation of the oxidase had no apparent effect on the distribution of any of these species between the cytoskeleton and the detergent extract. Our results support earlier studies implying that the cytoskeleton participates in an important way in regulating the activity of the O2(-)-forming respiratory burst oxidase of neutrophils.