The effect of estradiol and a combined estradiol/progestagen preparation on insulin sensitivity in healthy postmenopausal women.

Abnormalities of carbohydrate metabolism and insulin sensitivity have been reported in estrogen deficiency. Estrogen replacement appears to result in an improvement in these parameters, although progestagens may antagonize these effects. We have examined the effects of transdermal estradiol and oral norethisterone on insulin sensitivity using the hyperinsulinemic euglycemic clamp method by performing a randomized, double blind, placebo-controlled study in 22 healthy women after a surgically induced menopause. After baseline measurements, subjects were randomized to receive either transdermal 17beta-estradiol (50 microg) or matching placebo patches for 6 weeks. The subjects were then further randomized to receive either estradiol in combination with oral norethisterone (1 mg) or a matching oral placebo preparation, crossing over after 6 weeks, with assessment of insulin sensitivity at the end of each treatment. No significant increase in insulin sensitivity was observed after 6 weeks of transdermal 17beta-estradiol treatment (95% confidence interval, -0.54, 1.86; P = 0.27). Addition of norethisterone for a further 6 weeks had no detectable effect on insulin sensitivity (95% confidence interval, -1.65, 1.10; P = 0.65). The results of this study using transdermal estradiol do not support previous reports that unopposed estrogens exert potentially beneficial effects on insulin sensitivity and suggest that the addition of an oral progestagen confers no clinically important risk or benefit. It is therefore unlikely that effects on insulin sensitivity contribute appreciably to the cardioprotective benefits attributed to hormone replacement therapy.     

Hip fracture incidence in nursing home residents and community-dwelling older people,Washington State, 1993-1995

OBJECTIVES: To establish and validate a method of linking data from the Minimum Data Set (MDS) and Medicare hospital claims, to estimate hip fracture incidence rates for Medicare beneficiaries aged 65 and older in Washington State, and to compare the incidence rates of hip fractures in nursing home and non-nursing home residents. DESIGN: Retrospective analysis of Medicare population-based enrollment, hospital claims, and nursing home administrative data sets. SETTING: Nursing home and non-nursing home setting. PARTICIPANTS: Medicare beneficiaries in Washington State residing in the community or in skilled nursing facilities. MEASUREMENTS: Crude age- and sex-specific and standardized age- and sex-adjusted hip fracture incidence for persons residing and not residing in nursing homes. RESULTS: From October 1, 1993, through September 30, 1995, 7,812 Medicare beneficiaries aged 65 or older were hospitalized for hip fractures (6,566 fractures for 1,155,234 person-years of exposure in non-nursing home residents and 1,246 fractures for 42,986 person-years of exposure in nursing home residents). The standardized age- and sex-adjusted hip fracture rate of nursing home residents (23.0 per 1,000 person-years) substantially exceeded that of non-nursing home residents (5.7 per 1,000 person-years) (incidence rate ratio = 4.0, 95% confidence interval = 3.7-4.5). CONCLUSION: The incidence of hip fracture in nursing home residents far exceeds that in noninstitutionalized older people. Linkage of MDS and Medicare hospital claims data is a useful tool for epidemiological surveillance regarding events in nursing homes that are likely to result in hospitalization.     

Association studies between microsatellite markers within the gene encoding human 11beta-hydroxysteroid dehydrogenase type 1 and body mass index,waist to hip ratio,and glucocorticoid metabolism

Two isozymes of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) interconvert active cortisol (F) and inactive cortisone (E). 11beta-HSD1 is an oxo-reductase (E to F) expressed in several glucocorticoid target tissues, including liver and adipose tissue, where it facilitates glucocorticoid-induced gluconeogenesis and adipocyte differentiation, respectively. We have isolated a full-length HSD11B1 genomic clone; the gene is more than 30 kb in length, not 9 kb in length as previously reported, principally due to a large intron 4. Two polymorphic (CA)(n) repeats have been characterized within intron 4: a CA(19) repeat 2.7 kb 3' of exon 4 and a CA(15) repeat 3 kb 5' of exon 5. The microsatellites, CA(19) and CA(15), were PCR amplified using fluorescent primers and were genotyped on an ABI 377 DNA sequencer from DNA of 413 normal individuals enrolled in the MONICA study of cardiovascular risk factors and 557 Danish men (ADIGEN study), of whom 234 were obese [body mass index (BMI), >/=31 kg/m(2) ] at draft board examination and 323 were randomly selected controls from the draftee population with BMI below 31 kg/m(2) (mean +/- SE, 21.7 +/- 0.41). Genotypic data from the normal MONICA cohort was compared with gender, 5beta-tetrahydrocortisol+5alpha-tetrahydrocortisol/tetrahydrocortisone ratio, and waist to hip (W:H) ratio. When analyzed by allele length (0, 1, or 2 short alleles) for the CA(19) marker, there was a trend toward a higher 5beta-tetrahydrocortisol+5alpha-tetrahydrocortisol/tetrahydrocortisone ratio (P = 0.058) and an increased W:H ratio (2 vs. 0.1 short; P(c) = 0.10) with overrepresentation of short alleles. The opposite was true for the CA(15) locus, with longer alleles at this locus predicting increased 11beta-HSD1 activity, particularly in females. Genotypic data from the ADIGEN case-control population was compared with clinical markers of obesity such as BMI and W:H ratio. There was no significant difference in the distribution of either microsatellite marker between lean and obese groups. Allele distributions were binomial, as seen for the MONICA cohort, and the data were split accordingly (zero, one, or two short alleles). No significant association was seen between grouped alleles and the clinical parameters. No association was observed between HSD11B1 genotype and BMI in either population. These data suggest that 11beta-HSD1 is not a major factor in explaining genetic susceptibility to obesity per se. However, weak associations between HSD11B1 genotype, increased 11beta-HSD1 activity, and W:H ratio suggest that polymorphic variability at the HSD11B1 locus may influence susceptibility to central obesity through enhanced 11beta-HSD1 activity (E to F conversion) in visceral adipose tissue.     

Sex hormones induce insulin resistance in 3T3-L1 adipocytes by reducing cellular content of IRS proteins

Aim/hypothesis. Numerous studies have suggested a relation between sex hormones and insulin sensitivity but the ability of sex hormones to directly influence insulin action in peripheral tissues has not been investigated.¶Methods. We have examined the effects of estriol, estradiol and estrone on insulin action in cultured 3T3-L1 adipocytes, a useful model of adipocytes.¶Results. Treatment of these cells with each of these sex hormones resulted in a statistically significant reduction in the ability of insulin to stimulate glucose transport independently of a reduction in total cellular GLUT-4 content. This diminished ability of insulin to stimulate glucose transport was accompanied by a reduction in the total cellular content of insulin receptor substrates –1 and –2 and the p85α subunit of phosphatidylinositol 3'-kinase. By contrast, cellular content of protein kinase B was unchanged by hormone treatment but the magnitude of insulin-stimulated kinase activity was statistically significantly reduced after incubation with each of the sex hormones tested. We have further shown that treatment of 3T3-L1 adipocytes with these hormones alters the subcellular distribution of insulin receptor substrate proteins such that the particulate and soluble pools of these proteins were differentially affected by hormone treatment.¶Conclusion/interpretation. These data show that sex hormones can directly induce a state of insulin resistance in 3T3-L1 adipocytes in culture. The mechanism of this defect seems to be at least in part due to decreased cellular content and altered subcellular distribution of insulin receptor substrate proteins which in turn results in a reduction in proximal insulin-stimulated signalling cascades. [Diabetologia (2000) 43: 1374–1380]     

'You can't tell by looking': pilot study of a community-based intervention to detect asymptomatic sexually transmitted infections

Innovative and non-stigmatizing interventions are required to reduce ethnic inequalities in rates of sexually transmitted infections among young people. We therefore designed an intervention, 'You can't tell by looking,' which combined health promotion with testing for gonorrhoea and chlamydia using nucleic acid amplification technology and treatment and partner notification delivered in the non-clinical settings. One hundred and eighty-one participants were seen in 13 sessions in local further education colleges. Forty-three percent of participants were from Black Caribbean or Black Other ethnic groups and 39% were Black African: 125 of 181 participants were sexually active and 109 of these (87%) provided a urine specimen. 10/109 (9.2%, 95% confidence interval 4.5-16.2%) samples were confirmed positive for Chlamydia trachomatis and two were also positive for Neisseria gonorrhoeae. Only 7% of those tested found it embarrassing. The intervention was both feasible and acceptable to young people. It could be tested in a wider variety of non-clinical settings and evaluated in a cluster randomized trial.     

Late-onset apparent mineralocorticoid excess caused by novel compound heterozygous mutations in the HSD11B2 gene

Mutations in the gene encoding 11beta-hydroxysteroid dehydrogenase type 2, 11beta-HSD2 (HSD11B2), explain the molecular basis for the syndrome of apparent mineralocorticoid excess (AME), characterized by severe hypertension and hypokalemic alkalosis. Cortisol is the offending mineralocorticoid in AME, as the result of a lack of 11beta-HSD2-mediated cortisol to cortisone inactivation. In this study, we describe mutations in the HSD11B2 gene in 3 additional AME kindreds in which probands presented in adult life, with milder phenotypes including the original seminal case reported by Stewart and Edwards. Genetic analysis of the HSD11B2 gene revealed that all probands were compound heterozygotes, for a total of 7 novel coding and noncoding mutations. Of the 7 mutations detected, 6 were investigated for their effects on gene expression and enzyme activity by the use of mutant cDNA and minigene constructs transfected into HEK 293 cells. Four missense mutations resulted in enzymes with varying degrees of activity, all <10% of wild type. A further 2 mutations generated incorrectly spliced mRNA and predicted severely truncated, inactive enzyme. The mothers of 2 probands heterozygous for missense mutations have presented with a phenotype indistinguishable from "essential" hypertension. These genetic and biochemical data emphasize the heterogeneous nature of AME and the effects that heterozygosity at the HSD11B2 locus can have on blood pressure in later life.     

Is altered adrenal steroid biosynthesis a key intermediate phenotype in hypertension?

Approximately 10% of patients with hypertension have a high ratio of aldosterone to renin, but the reason for this and the relationships among low-renin essential hypertension, elevation of the ratio, and true primary aldosteronism are unclear. We have previously reported that a polymorphism of the gene (C-to-T conversion at position -344) encoding aldosterone synthase is associated with hypertension, particularly in patients with a high ratio. However, the most consistent association with this variant is a relative impairment of adrenal 11beta-hydroxylation. In this review, we propose that altered conversion of deoxycortisol to cortisol leads to a subtle, chronic increase in adrenocortrophin drive to the adrenal cortex, with eventual development of hyperplasia. In combination with other genetic or environmental factors (such as dietary sodium intake), we suggest that this might be responsible for the long-term development of a resetting of the aldosterone response to angiotensin II, giving rise to the phenotype of hypertension with a raised ratio. In some subjects, this may progress further to true primary aldosteronism with a dominant adrenal nodule. Thus, there may be a genetically influenced continuum from hypertension with a normal ratio, through hypertension with a raised ratio, and primary aldosteronism.     

The atrioventricular junctions in Ebstein malformation

OBJECTIVE—To review the anatomical structure of the right atrioventricular junction, including the specialised atrioventricular conduction system, in hearts with Ebstein's malformation, to identify potential substrates for the abnormalities in conduction.
METHODS—Five heart specimens representing the morphological spectrum of Ebstein malformation were examined grossly and histologically.
RESULTS—On the endocardial surface, the atrioventricular junction was marked by a faint line in two hearts, and by a small ridge in the other three. Analysis of the right parietal junction in four hearts revealed only two accessory muscular atrioventricular connections. A plane of fibrofatty tissue separated atrial from ventricular myocardium in the right parietal junction in all hearts. The compact atrioventricular node was closer to the coronary sinus than usual. Accessory nodoventricular connections were present in four hearts, while accessory fasciculo-ventricular connections were found in one. The right bundle branch was hypoplastic or absent in four hearts.
CONCLUSIONS—In this small series, the parietal atrioventricular junction was better developed than previously thought. Structural abnormalities of the atrioventricular conduction system, however, were present. These may account for some of the conduction abnormalities frequently observed with the Ebstein malformation.


Keywords: Ebstein's anomaly; atrioventricular node; bundle branch block; Wolff-Parkinson-White syndrome     

Use and effectiveness of dapagliflozin in routine clinical practice: An Italian multicentre retrospective study

In randomized controlled trials (RCTs), sodium‐glucose co‐transporter‐2 (SGLT2) inhibitors have been shown to confer glycaemic and extra‐glycaemic benefits. The DARWIN‐T2D (DApagliflozin Real World evIdeNce in Type 2 Diabetes) study was a multicentre retrospective study designed to evaluate the baseline characteristics of patients receiving dapagliflozin vs those receiving selected comparators (dipeptidyl peptidase‐4 inhibitors, gliclazide, or glucagon‐like peptide‐1 receptor agonists), and drug effectiveness in routine clinical practice. From a population of 281 217, the analysis included 17 285 patients initiating dapagliflozin or comparator glucose‐lowering medications (GLMs), 6751 of whom had a follow‐up examination. At baseline, participants starting dapagliflozin were younger, had a longer disease duration, higher glycated haemoglobin (HbA1c) concentration, and a more complex history of previous GLM use, but the clinical profile of patients receiving dapagliflozin changed during the study period. Dapagliflozin reduced HbA1c by 0.7%, body weight by 2.7 kg, and systolic blood pressure by 3.0 mm Hg. Effects of comparator GLMs were also within the expected range, based on RCTs. This real‐world study shows an initial channelling of dapagliflozin to difficult‐to‐treat patients. Nonetheless, dapagliflozin provided significant benefits with regard to glucose control, body weight and blood pressure that were in line with findings from RCTs.