Relationships between muscle morphology and insulin sensitivity are improved after adjustment for intra-individual variability in 70-year-old men

The purpose of this investigation was to examine to what extent variability in the muscle morphology and insulin sensitivity influence the correlation between them. Reproducibility of muscle characteristics was estimated in duplicate biopsies from the same thigh of 23 subjects from a cohort of 70-year-old men. The coefficient of variation (CV) for different characteristics of muscle morphology was between 11 and 42% in duplicate biopsies. Coefficient of variation for markers of insulin sensitivity ranged between 12 and 39%. The variability reflected by intra-class correlation ranged from 0.23 to 0.60 for muscle morphology and from 0.68 to 0.96 for estimates of insulin sensitivity. The correlation analysis between muscle morphology and insulin resistance was performed in a sample of 515 men from the cohort, correlation coefficients were calculated with (rtrue) and without (r) adjustment for intra-individual variation. Insulin sensitivity showed a positive relationship with percentage of type I fibres (rtrue=0.33, r=0.21; P < 0.0001) and capillary density (rtrue=0.43, r=0.21; P < 0. 0001) and negative correlations with percentage of type IIB fibres (rtrue=-0.35, r=-0.24; P < 0.0001). Capillary density was inversely correlated to insulin. Thus, an obvious improvement of the correlation was seen after correcting intra-individual variation. In conclusion, owing to the low degree of reproducibility of muscle morphology variables and insulin sensitivity, implying a noticeable underestimation of correlations, the r-values should be adjusted for within-subject variation in order to demonstrate a more accurate estimate of the strength of the relationships studied.

Reliability of anthropometric measurements in overweight and lean subjects: consequences for correlations between anthropometric and other variables

OBJECTIVE

To estimate the reliability of anthropometric measurements in overweight and lean subjects, and to examine the influence of this reliability on correlations to other variables, since low reliability leads to underestimation of correlations.

DESIGN

Replicate measurements by two observers in 26 overweight and 25 lean subjects measured at two occasions.

MEASUREMENTS

Sagittal abdominal diameter (SAD), waist circumference (waist), waist-to-hip ratio (W/H) and skinfold measurements.

RESULTS

Intra-class correlation coefficients (ICCs) for SAD and waist were higher than for W/H (0.98 vs. 0.90, P<0.001, and 0.97 vs. 0.90, P = 0.001, respectively). For waist, the ICC was lower for overweight than for lean subjects (0.85 vs 0.95, P=0.030), but the ICC values were comparable for SAD and W/H (0.92 vs. 0.95 and 0.78 vs. 0.83, respectively). Intra-observer variations (IOV) for SAD and waist were lower than for W/H (coefficients of variation; 1.6%, 1.4% and 2.3%, respectively), as were intra-subject variations (ISV) (2.7%, 3.0% and 3.4%, respectively). ICC values ranged from 0.84 to 0.93 and were lower for overweight than for lean subjects for biceps, subscapular and umbilical skinfolds (P=0.031, P<0.001 and P=0.048, respectively). Coefficients of variations for skinfold measurements ranged between 7.3% and 16.0% for IOV and between 14.9% and 20.8% for ISV.

CONCLUSIONS

The low ICC values imply that correlations can be underestimated in overweight groups. We propose that, because of their higher reliability, SAD and waist have a higher predictive capacity for cardiovascular risk than W/H. SAD is the only measurement with high reliability in both weight groups and its use is recommended.

Ciprofloxacin for treatment of tularemia in children

BACKGROUND

Children with tularemia are, irrespective of severity of disease, usually subjected to parenteral treatment with aminoglycosides. Based on available susceptibility testing, quinolones might be effective oral alternatives of parenteral therapy. These drugs cause arthropathy in immature animals, but this risk is currently regarded to be low in humans.

PATIENTS AND METHODS

In 12 patients (median age, 4 years; range, 1 to 10) with ulceroglandular tularemia, a 10- to 14-day course of oral ciprofloxacin, 15 to 20 mg/kg daily in 2 divided doses, was prescribed. Microbiologic investigations included identification of the infectious agent by PCR and culture of wound specimens, as well as determination of antibiotic susceptibility of isolates of Francisella tularensis.

RESULTS

Defervescence occurred within 4 days of institution of oral ciprofloxacin in all patients. After a median period of 4.5 days (range, 2 to 24), the patients were capable of outdoor activities. In 2 cases, treatment was withdrawn after 3 and 7 days because of rash. In both cases a second episode of fever occurred. All children recovered without complications. In 7 cases F. tularensis was successfully cultured from ulcer specimens and tested for susceptibility to ciprofloxacin. MIC values for all isolates were 0.03 mg/l.

CONCLUSION

In our sample of 12 patients ciprofloxacin was satisfactory for outpatient treatment of tularemia in children.

Sagittal abdominal diameter compared with other anthropometric measurements in relation to cardiovascular risk

BACKGROUND

Abdominal adiposity has been described as an independent risk factor for coronary heart disease. Sagittal abdominal diameter has been found to be closely related to the amount of visceral adipose tissue.

AIM

To compare the sagittal abdominal diameter with other anthropometric measures regarding their relationships to risk factors for coronary heart disease (CHD).

DESIGN

A study of 885 men and women participating in a health survey.

MEASUREMENTS

Sagittal abdominal diameter, body mass index (BMI), waist and hip circumferences, waist-to-hip ratio, serum concentrations of risk factors for CHD, blood pressure.

RESULTS

In men the sagittal abdominal diameter showed stronger correlations to the CHD risk factors serum cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, glucose, insulin, apolipoprotein B (apoB), plasminogen activator inhibitor tissue-type plasminogen activator (t-PA) and lipid-corrected alpha tocopherol, and to systolic and diastolic blood pressures than the other anthropometric measurements. In women, compared with the other anthropometric measurements the sagittal abdominal diameter was more strongly correlated to serum cholesterol, LDL cholesterol, LDL/HDL (high-density lipoprotein), apo B and t-PA, and to systolic and diastolic blood pressure. The sagittal abdominal diameter showed a stronger correlation to 'total risk' for cardiovascular disease (+ 0.66 for men, 0.62 for women), than waist circumference (+ 0.63 for men, + 0.57 for women) and waist-to-hip ratio (+ 0.61 for men and +0.48 for women; P <0.0001 for all correlations). This diameter was also more strongly correlated to 'metabolic risk' (+ 0.64 for men, + 0.59 for women) than waist circumference (+ 0.60 for men, + 0.59 for women) and waist-to-hip ratio (+ 0.58 for men, + 0.52 for women)(P < 0.0001 for all correlations). In a regression analysis including the anthropometric measurements and the risk values, the sagittal diameter was the strongest measure of cardiovascular risk in both men and women.

CONCLUSIONS

Among both men and women in this study the sagittal abdominal diameter showed stronger correlations to cardiovascular risk and to other risk factors in the metabolic syndrome than other anthropometric variables such as waist circumference, waist-to hip ratio and BMI.

Normal ovulatory women with polycystic ovaries have hyperandrogenic pituitary-ovarian responses to gonadotropin-releasing hormone-agonist testing

Women with polycystic ovary syndrome (PCOS) have chronic anovulation and hyperandrogenism and frequently have abnormalities in their lipid profiles and insulin/insulin-like growth factor axis that increase their lifetime risk for cardiovascular disease. Normal ovulatory women may have polycystic ovaries on ultrasonography and yet lack the clinical features of PCOS. To further explore whether ovulatory women without clinical/biochemical hyperandrogenism but with polycystic appearing ovaries (ov-PAO) have subclinical features of PCOS, we prospectively characterized 26 ov-PAO women and matched them by age and body mass index to 25 ovulatory women with normal appearing ovaries (ov-NAO) and to 22 women with PCOS. After an overnight fast, all women had baseline endocrine and metabolic assessments. In addition, a subset of each group of women underwent GnRH-agonist (leuprolide acetate 1 mg s.c.) testing, ACTH stimulation, and an insulin tolerance test (ITT). At baseline, ov-PAO and ov-NAO women had similar endocrine profiles (LH, LH:FSH, androstenedione, and DHEAS). Compared with ov-NAO, 31% of ov-PAO women had reduced glucose responses after insulin (K(itt)), suggesting mild insulin resistance, and 35% had high density lipoprotein levels below 35 mg/dL, a level considered to represent significant cardiovascular risk. After GnRH-agonist, ov-PAO women had response patterns in LH, total testosterone, and 17-hydroxyprogesterone (17-OHP) that were intermediate between ov-NAO and women with PCOS. Ovarian responses were above the normal range in 30-40% of women with ov-PAO. In ov-PAO, peak responses of LH after leuprolide correlated with triglyceride levels (P < 0.05) and peak responses of 17-OHP correlated inversely with Kitt values (P < 0.05). No significant differences were noted with ACTH testing. In conclusion, occult biochemical ovarian hyperandrogenism may be uncovered using GnRH-agonist in ovulatory women with ov-PAO, while adrenal responses remain normal. Subtle metabolic abnormalities may also be prevalent.

The A3 pulley

The tendon-pulley geometry and gliding resistance with and without the A3 pulley were compared in 6 fresh human cadaver fingers. We measured the x-ray images of the distal A2 pulley-tendon angle and proximal A4 pulley-tendon angle with varying degrees of proximal interphalangeal joint flexion between 0 degrees and 120 degrees before and after A3 pulley resection. The gliding resistance of the flexor digitorum profundus tendon under the A2 pulley was also measured at varying tendon-pulley angles. With the A3 pulley removed, the tendon-pulley angle significantly increased compared with the A3 intact state. The gliding resistance between tendon and pulley quadratically increased as the tendon-pulley angle increase from 0 degrees to 60 degrees. These results indicate that the A3 pulley might serve to reduce tendon-pulley gliding resistance by reducing the tendon-pulley angle during finger flexion.

Polymorphism in the glycogen-associated regulatory subunit of type 1 protein phosphatase (PPP1R3) gene and insulin sensitivity

A polymorphism (PP1ARE) in the 3'-untranslated region of the gene encoding the glycogen-associated regulatory subunit of type 1 protein phosphatase PPP1R3 is associated with insulin resistance in Pima Indians. The aim of this study was to investigate whether two common variants in the PPP1R3 gene, Asp905Tyr and PP1ARE, are associated with reduced insulin sensitivity or can predict the development of impaired glucose tolerance (IGT) or type 2 diabetes during a 20-year follow-up period in 696 50-year-old Caucasian men. The allelic frequency of Tyr905 was 0.11 (95% CI 0.09-0.13) and of PP1ARE 0.34 (0.31-0.37) and the two polymorphisms were in linkage disequilibrium (chi2 = 46, P < 0.0001, Fisher's exact test). None of the polymorphisms was associated with the development of IGT or type 2 diabetes, but the PP1ARE polymorphism was weakly correlated to whole-body insulin sensitivity (r = -0.08, P = 0.04). In conclusion, we found no evidence in Swedish men that the PP1ARE or the Asp905Tyr variants over a 20-year period predict the development of IGT or type 2 diabetes, but the PP1ARE polymorphism could have a higher penetrance in other populations.

Comparative analysis of PCR versus culture for diagnosis of ulceroglandular tularemia

PCR and culture were comparatively evaluated for their abilities to demonstrate Francisella tularensis in wound specimens from tularemia patients during an outbreak in Sweden in 1998. For transport of the specimens used for PCR, a buffer solution containing a nuclease inhibitor was used, and for transport of the specimens used for culture, a commercial transport system was selected after experimental comparison of various systems. Of 40 patients with culture- and/or serology-verified ulceroglandular tularemia, PCR detected F. tularensis DNA in 30 (75%) patients, whereas culture detected bacterial growth in 25 (62%) patients. Compared to data from a previous study, the present inclusion of a nuclease inhibitor in the transport medium did not improve the sensitivity of the PCR, whereas the sensitivity of the culture procedure was significantly increased by selection of the system used for transport. Among eight patients with clinically suspected tularemia but with negative serology and culture, specimens from four patients showed detectable DNA. In three of these patients the diagnosis was verified by the demonstration of an F. tularensis-specific T-cell response in vitro. In conclusion, PCR was more sensitive than culture for demonstration of F. tularensis in wound specimens. Besides, we showed that tularemia may proceed without development of serum antibodies, and in these patients, PCR may be of special importance for verification of the diagnosis.

Transthyretin in high density lipoproteins: association with apolipoprotein A-I

Previous studies have revealed the presence of transthyretin (TTR) on lipoproteins. To further address this issue, we fractionated plasma lipoproteins from 9 normal individuals, 10 familial amyloidotic polyneuropathy (FAP) patients, and 19 hyperlipidemic subjects using gel filtration. In the majority of the subjects, as well as in 9 of the 10 FAP patients and 14 of the 19 patients with hyperlipidemia, TTR was detected by ELISA in the high density lipoprotein (HDL) fraction. The presence of TTR in HDL was confirmed by direct sequencing and by immunoblotting; using non-reducing conditions, TTR was found by immunoblotting in a high molecular weight complex, which reacted also for apolipoprotein A-I (apoA-I). The amount of TTR present in HDL (HDL-TTR), as quantified by ELISA corresponded to 1;-2% of total plasma TTR. However, no detectable TTR levels were found in HDL fraction from 6 of the hyperlipidemic subjects. No correlation was found between the lack of TTR in HDL and plasma levels of total, LDL-, or HDL-associated cholesterol as well as levels of apoA-I and total plasma TTR. Ligand binding experiments showed that radiolabeled TTR binds to the HDL fraction of individuals with HDL-TTR but not to the corresponding fractions of individuals devoid of HDL-TTR, suggesting that HDL composition may interfere with TTR binding. The component(s) to which TTR binds in the HDL fraction were investigated. Polyclonal antibody against apoA-I was able to block the interaction of TTR with HDL, suggesting that the interaction of TTR with the HDL particle occurs via apoA-I. This hypothesis was further demonstrated by showing the formation of a complex of TTR with HDL and apoA-I by crosslinking experiments. Furthermore, anti-apoA-I immunoblot under native conditions suggested the existence of differences in HDL particle properties and/or stability between individuals with and without HDL-TTR.

Regulated exocytosis in immune function: are SNARE-proteins involved?

Inflammation is an important feature in the pathogenesis of most chronic lung diseases. It is characterized by tissue infiltration with various inflammatory cells, including eosinophils, mast cells, basophils, macrophages, neutrophils, T- and B-lymphocytes and dendritic cells (1). In the tissue granulocytes release their toxic granule proteins after being stimulated by soluble mediators released by other inflammatory cells (2). Therefore, it is important to characterize the intracellular mechanisms regulating the transport of the granule contents in inflammatory cells. Intracellular vesicle-traffic in mammalian cells is mediated by transport vesicles that emerge from donor compartments and are specifically targeted to acceptor compartments where they deliver their contents after membrane fusion (3). This traffic leads to three types of fusion: vesicle-intracellular membranes, vesicle-vesicle or vesicle-plasma membrane. The process leading to fusion of vesicle-plasma membrane is called exocytosis, and it delivers proteins to the cell surface (receptors e.g. CD11b, CD18) and exports soluble molecules (mediators e.g. ECP) from the cell. A number of key proteins involved in regulated exocytosis have been identified from inflammatory cells. This review is a brief summary of these proteins and it includes recent results from studies on regulated exocytosis in inflammatory cells.

HDL-subpopulation patterns in response to reductions in dietary total and saturated fat intakes in healthy subjects

BACKGROUND

Little information is available about HDL subpopulations during dietary changes.

OBJECTIVE

The objective was to investigate the effect of reductions in total and saturated fat intakes on HDL subpopulations.

DESIGN

Multiracial, young and elderly men and women (n = 103) participating in the double-blind, randomized DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activities) Study consumed 3 different diets, each for 8 wk: an average American diet (AAD: 34.3% total fat,15.0% saturated fat), the American Heart Association Step I diet (28.6% total fat, 9.0% saturated fat), and a diet low in saturated fat (25.3% total fat, 6.1% saturated fat).

RESULTS

HDL(2)-cholesterol concentrations, by differential precipitation, decreased (P < 0.001) in a stepwise fashion after the reduction of total and saturated fat: 0.58 +/- 0.21, 0.53 +/- 0.19, and 0.48 +/- 0.18 mmol/L with the AAD, Step I, and low-fat diets, respectively. HDL(3) cholesterol decreased (P < 0.01) less: 0.76 +/- 0.13, 0.73 +/- 0.12, and 0.72 +/- 0.11 mmol/L with the AAD, Step I, and low-fat diets, respectively. As measured by nondenaturing gradient gel electrophoresis, the larger-size HDL(2b) subpopulation decreased with the reduction in dietary fat, and a corresponding relative increase was seen for the smaller-sized HDL(3a, 3b), and (3c) subpopulations (P < 0.01). HDL(2)-cholesterol concentrations correlated negatively with serum triacylglycerol concentrations on all 3 diets: r = -0.46, -0.37, and -0.45 with the AAD, Step I, and low-fat diets, respectively (P < 0.0001). A similar negative correlation was seen for HDL(2b), whereas HDL(3a, 3b), and (3c) correlated positively with triacylglycerol concentrations. Diet-induced changes in serum triacylglycerol were negatively correlated with changes in HDL(2) and HDL(2b) cholesterol.

CONCLUSIONS

A reduction in dietary total and saturated fat decreased both large (HDL(2) and HDL(2b)) and small, dense HDL subpopulations, although decreases in HDL(2) and HDL(2b) were most pronounced.

Insulin-mediated vasodilation and glucose uptake are independently related to fasting serum nonesterified fatty acids in elderly men

OBJECTIVES

To investigate candidate predictors for insulin sensitivity in healthy elderly males, with special reference to the influence of insulin-mediated skeletal muscle blood flow and serum nonesterified fatty acids (NEFA).

SUBJECTS

From the participants in a health survey of 70-year-old males, focusing on cardiovascular risk factors, a subgroup of 46 men was sampled. Only men who declared themselves healthy and without medication were included.

INTERVENTIONS

Insulin sensitivity was measured with the euglycaemic hyperinsulinaemic clamp. Leg blood flow was measured before and during the clamp, using the Doppler ultrasound technique.

RESULTS

Hyperinsulinaemia [steady-state plasma insulin 105(15) mU L-1] increased leg blood flow by 10% (P < 0.004). When tested in bivariate analysis incremental leg blood flow was only significantly related to the serum NEFA concentration (r = - 0.38, P < 0.01) amongst a number of measured variables. Insulin-mediated glucose disposal was related to body mass index (BMI) (r = -0.49, P = 0. 0006), waist/hip ratio (r = - 0.31, P = 0.036), NEFA (r = - 0.50, P = 0.0004) and heart rate (r = - 0.34, P = 0.02). In multivariate analysis only BMI and NEFA remained significantly related to whole-body glucose uptake.

CONCLUSIONS

The study demonstrates that in elderly men BMI and fasting serum NEFA but not insulin-induced vasodilation are related to insulin sensitivity. High fasting levels of NEFA relate to both impaired insulin-mediated vasodilation and impaired glucose disposal, respectively. These two insulin actions were not interrelated, however, a finding which may indicate dissociated mechanisms.

Isolation of adipophilin and butyrophilin from bovine milk and characterization of a cDNA encoding adipophilin

The milk fat globule membrane-associated proteins adipophilin (alias adipocyte differentiation-related protein) and butyrophilin were purified from bovine milk by reverse-phase chromatography. The nucleotide sequence of bovine adipophilin was obtained via peptide mapping and sequencing of a mammary gland cDNA clone, which comprises 1841 nucleotides and has an open reading frame of 450 amino acids. By peptide mapping, 19% of the amino acid sequence was confirmed. The obtained amino acid sequence has 87 and 80% identical residues with human and mouse adipophilin, respectively. Alignment with the proteins perilipin and TIP47 revealed two highly conserved segments, which may assemble into amphipathic alpha-helices.

VAMP-1 has a highly variable C-terminus generated by alternative splicing

VAMP-1 (synaptobrevin1) is one of the key proteins in the SNARE complex which is involved in regulated exocytosis. Recently, Isenmann et al. (1998, Mol. Biol. Cell 9, 1649-1660) showed the extreme C-terminal region of VAMP-1A and 1B to be involved in subcellular targeting of the isoforms. Four new splice variants (VAMP-1C to F) were identified in addition to the previously published variants VAMP-1A and VAMP-1B. Interestingly, the four new isoforms also have variable sequences only at the extreme C-terminus. This suggests that the C-terminal region has an important function for VAMP-1 and vesicle targeting. All six variants were a result of alternative splicing that linked exons 1-4 which encode the conserved region of VAMP-1 with one of the exons 5A to 5F that encodes the highly variable extreme C-terminus. Exon (5A-E) encode C-termini of two to five amino acid residues, whereas exon 5F encoded a long C-terminal amino acid extension. The splice variants were differentially expressed in human brain, kidney, and inflammatory cells.

Search for variants of the gene-promoter and the potential phosphotyrosine encoding sequence of the insulin receptor substrate-2 gene: evaluation of their relation with alterations in insulin secretion and insulin sensitivity

AIMS/HYPOTHESIS

The aim of this study was to screen part of the putative promoter sequence in addition to 14 potential phosphotyrosine residues of human IRS-2 for genetic variability which might cause changes in protein expression or function. Furthermore, the potential impact on insulin secretion and sensitivity of a previously identified IRS-2 variant (Gly1057Asp) was analysed.

METHODS

The screenings were carried out by the SSCP-heteroduplex technique on DNA from Type II (non-insulin-dependent) diabetic patients. The impact of the Gly1057Asp variant was analysed in four glucose-tolerant Scandinavian study groups.

RESULTS

The results showed no nucleotide substitutions in the promoter sequence, however, a novel heterozygous amino acid variant was identified (Leu647Val). In an association study, the new variant was found in 3 of 413 diabetic patients and in none of 280 glucose tolerant subjects. The variant did not affect the binding of IRS-2 to the insulin receptor or p85alpha of phosphatidylinositol 3-kinase when measured in the yeast two-hybrid system. Examination of the common Gly1057Asp variant in 363 young healthy subjects and in 228 glucose tolerant offspring of one diabetic parent showed no differences in insulin secretion or insulin sensitivity after an intravenous glucose tolerance test. Glucose tolerant middle-aged subjects homozygous for the polymorphism (n = 31), however, had on average a 25 % decrease in fasting serum insulin concentrations (p = 0.009) and 28 % (p = 0.01) and 34 % (p = 0.003) reductions in serum insulin concentrations at 30 and 60 min, respectively, during an OGTT compared with wildtype carriers (n = 107). In a cohort of 639 elderly Swedish men the amino acid variant did not have any detectable impact on insulin secretion after an OGTT.

CONCLUSION/INTERPRETATION

No genetic variability was found in the IRS-2 promoter. A rare IRS-2 variant at codon 647 has been identified in Type II diabetic patients. The prevalent codon 1057 polymorphism had no consistent effect on insulin secretion or insulin sensitivity. [Diabetologia (1999) 42: 1244-1249]

Relations of plasma fibrinogen level in children to measures of obesity, the (G-455-->A) mutation in the beta-fibrinogen promoter gene, and family history of ischemic heart disease: the Columbia University BioMarkers Study

Higher plasma fibrinogen levels are associated with increased risk of myocardial infarction in adults, but little is known about factors that influence fibrinogen levels in childhood. The authors examined the associations of measures of obesity, presence of the (G-455-->A) allele in the beta-fibrinogen promoter gene, and family history of early onset of ischemic heart disease with plasma fibrinogen levels in children. Children (n = 299) were recruited during 1994-1997 from 276 families living in a racially mixed area of New York City. The mean age of the study children was 9.9 years; 79% were Hispanic. The frequency of the (G-455-->A) allele was lower in Hispanics than in non-Hispanic Whites (15.5% vs. 28.3% in children (p < 0.01) and 13.9% vs. 28.3% in parents (p < 0.001)). Graded relations of children's plasma fibrinogen levels were found with tertiles of body mass index (weight (kg)/height (m)2) and sum of skinfolds (tests for linear trend: p < 0.001). Plasma fibrinogen levels in the children were not related to race/ethnicity, presence of the (G-455-->A) allele, or family history. Multiple linear regression analyses adjusting plasma fibrinogen levels for age, sex, race/ethnicity, the (G-455-->A) allele, and family history of early onset of heart disease showed a significant association with either body mass index or sum of skinfolds (p < 0.001 for both models) but not with the other variables.

Sequence, S-S bridges, and spectra of bovine transcobalamin expressed in Pichia pastoris

Transcobalamin (TC) -encoding cDNA was isolated from a bovine mammary gland cDNA library. Hybridization of the cloned bovine TC-cDNA to RNA samples from bovine tissues showed that the most intensive synthesis of a TC positive 1.9-kilobase mRNA occurred in kidney, lymphatic nodes, and liver. Bovine TC was expressed in yeast Pichia pastoris, and the isolated recombinant protein showed cobalamin (Cbl) and receptor binding properties similar to TCs from other sources. Alignment of the related Cbl carriers (haptocorrins and intrinsic factors from other species) with bovine TC (414 residues) revealed four conservative clusters in the sequence (85-98, 137-147, 178-190, and 268-288), which may be responsible for Cbl binding. Three S-S bonds connected Cys residues 3-252, 98-294, and 147-190. Treatment with an S-S reducing agent caused liberation of Cbl from TC-Cbl. A significant change was observed in the TC-Cbl absorbance spectrum upon substitution of Co(2+)-coordinated H(2)O by azide. The reaction developed several orders of magnitude slower, and the spectral distortions were much stronger than those in free Cbl. This may be caused by significant deformation of the Cbl molecule and/or by its shielding when bound to TC.

Constraint and material properties of the subregions of the scapholunate interosseous ligament

The material and constraint properties of the dorsal, proximal, and palmar regions of the scapholunate ligament were studied using isolated bone-ligament-bone preparations from 24 adult intact cadaver wrists. Determinations of constraint to differential rotation and translation as well as failure strength were made using a servohydraulic testing machine incorporating an additional rotatory actuator. The dorsal region of the scapholunate ligament offered the greatest constraint to differential translation, while both the dorsal and palmar regions demonstrated statistically significant combined constraints to differential rotation between the scaphoid and lunate. The greatest yield strength was found in the dorsal region (260.3 N +/- 118.1 N), followed by the palmar region (117.9 N +/- 21.3 N) and the proximal region (62.7 N +/- 32.2 N).

APOE genotype, plasma lipids, lipoproteins, and AD in community elderly

BACKGROUND

Genetic variation at the APOE locus has a major influence on both plasma lipid levels and the risk of AD. The relationship between APOE genotype and plasma lipids may influence the risk of AD.

OBJECTIVE

In a community-based study of white, African American, and Caribbean Hispanic elderly in New York City, we investigated the relationship between plasma lipids and AD as well as the possible influence of APOE genotype on this relationship.

METHODS

Total plasma cholesterol (TC), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride levels were investigated in a cross-sectional study of nondemented elderly and patients with AD and in a prospective study of incident AD. Analyses included APOE genotype, gender, ethnicity, body mass index, and other potential confounders such as a history of hypertension, smoking, aspirin use, previous stroke, or ischemic heart disease.

RESULTS

Compared with nondemented elderly, decreased TC level had a weak but significant inverse association with incident AD, independent of APOE genotype. No other lipoprotein fragment was associated with either prevalent or incident AD.

CONCLUSION

Our results suggest that no consistent relationship exists between APOE genotype, plasma lipoproteins, and AD.

Plasma endothelin-1 and total insulin exposure in diabetes mellitus

Insulin stimulates endothelin-1 (ET-1) expression in a dose-response relationship, and ET-1 effects on vascular wall structure are similar to the long-term complications of diabetes. We therefore determined whether the plasma ET-1 concentration in patients with diabetes is associated with their total insulin exposure to see if plasma ET-1 might be a link between insulin exposure and long-term complications of diabetes. We studied 69 patients with Type I and 40 patients with Type II diabetes mellitus in equally tight glycaemic control for 2 years in a cross-sectional design. We measured basal and glucagon-stimulated plasma C-peptide, abdominal sagittal diameter, skinfold thickness, glomerular filtration rate, albumin excretion rate and standard clinical characteristics. Mean HbA1c was 6.4% in Type I and 6.3% in Type II diabetes. Patients with an albumin excretion rate >300 microg/min were excluded. Adjusted mean plasma ET-1 was 4.11 (S.E.M. 0.39) pg/ml in 21 normal subjects, 3.47 (0.19) pg/ml in Type I diabetes and 4.84 (0.26) pg/ml in Type II diabetes (P=0.0001). In all patients with measurable plasma C-peptide, plasma ET-1 was associated with basal plasma C-peptide (r=0.5018, P<0.0001), with stimulated plasma C-peptide (r=0.5379, P<0.0001), and with total daily insulin dose (r=0.2219, P=0.00851). Abdominal obesity, metabolic abnormalities, blood pressure and glomerular filtration rate were not associated with plasma ET-1, when corrected for C-peptide and daily insulin dose. Our study shows that the plasma concentration of ET-1 is closely associated with insulin secretion and insulin dose in patients with diabetes. Plasma ET-1 is higher in Type II diabetes than in Type I diabetes. Increased insulin exposure in patients with diabetes may have long-term effects on vascular wall structure through its stimulation of ET-1 expression.

Effect of long-term beta-carotene and vitamin A on serum cholesterol and triglyceride levels among participants in the Carotene and Retinol Efficacy Trial (CARET)

OBJECTIVE

The Carotene and Retinol Efficacy Lung Cancer Chemoprevention Trial (CARET) ended prematurely due to the unexpected findings that the active treatment group on the combination of 30 mg beta-carotene and 25,000 IU retinyl palmitate had a 46% increased lung cancer mortality and a 26% increased cardiovascular mortality compared with placebo. This study was designed when the CARET intervention was halted to evaluate the effects of long-term supplementation with beta-carotene and retinol on serum triglyceride and cholesterol levels, in an attempt to explore possible explanations for the CARET result.

METHODS

Serum triglyceride levels, and total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol levels were determined in a subgroup of 52 CARET participants. Baseline and mid-trial levels were available on 23 participants on placebo and 29 on active treatment who were then serially followed for 10 months after trial termination.

RESULTS

Triglyceride, and total, HDL and LDL cholesterol levels were similar in the two groups at baseline. After a mean of 5 years on the intervention there was a small nonsignificant increase in serum triglyceride levels in the active group, but no difference in total, HDL, or LDL cholesterol levels. After stopping the intervention there was a decrease in triglyceride levels in the active intervention group, and no change in the other parameters.

CONCLUSION

Based on a small convenience sample, CARET participants in the active treatment arm had a small nonsignificant increase in serum triglyceride levels while on the intervention, and a decrease in serum triglyceride levels after the intervention was discontinued. No significant changes in total or HDL cholesterol were noted. These results argue against a major contribution of treatment-induced changes in serum lipid and lipoprotein levels to the increased cardiovascular mortality in the active treatment group.

Low-density lipoprotein cholesterol and the risk of dementia with stroke

CONTEXT

Next to Alzheimer disease, vascular dementia is the second most common form of dementia in the elderly, yet few specific risk factors have been identified.

OBJECTIVE

To investigate the relationship of plasma lipids and lipoproteins to dementia with stroke.

DESIGN AND SETTING

Prospective longitudinal community-based study over a 7-year period (1991-1998).

PARTICIPANTS

A total of 1111 nondemented participants (mean [SD] age, 75.0 [5.9] years) were followed up for an average of 2.1 years (range, 1-7.8 years).

MAIN OUTCOME MEASURE

Incident dementia with stroke according to standardized criteria, by baseline levels of total plasma cholesterol and triglycerides, low-density lipoprotein (LDL) cholesterol, LDL levels corrected for lipoprotein(a), high-density lipoprotein cholesterol, lipoprotein(a), and apolipoprotein E genotype.

RESULTS

Two hundred eighty-six (25.7%) of the 1111 subjects developed dementia during follow-up; 61 (21.3%) were classified as having dementia with stroke and 225 (78.7%) as having probable Alzheimer disease. Levels of LDL cholesterol were significantly associated with an increased risk of dementia with stroke. Compared with the lowest quartile, the highest quartile of LDL cholesterol was associated with an approximately 3-fold increase in risk of dementia with stroke, adjusting for vascular risk factors and demographic variables (relative risk [RR], 3.1; 95% confidence interval [CI], 1.5-6.1). Levels of LDL corrected for lipoprotein(a) were an even stronger predictor of dementia with stroke in the adjusted multivariate analysis. Compared with the lowest quartile, the RR of dementia with stroke for the highest quartile of lipoprotein(a)-corrected LDL cholesterol was 4.1 (95% CI, 1.8-9.6) after adjusting for vascular factors and demographic variables. Lipid or lipoprotein levels were not associated with the development of Alzheimer disease in our cohort.

CONCLUSIONS

Elevated levels of LDL cholesterol were associated with the risk of dementia with stroke in elderly patients. Further study is needed to determine whether treatment of elevated LDL cholesterol levels will reduce the risk of dementia with stroke.

Heme oxygenase inhibitors transiently increase serum ferritin concentrations without altering other acute-phase reactants in man

Sn protoporphyrin (SnPP) and Sn mesoporphyrin (SnMP), potent inhibitors of heme oxygenase (HO), significantly suppress bilirubin production, lower serum and biliary bilirubin levels and increase biliary heme output in animals and man. In this study, 20 healthy volunteers, 7 patients with primary biliary cirrhosis and 4 patients with idiopathic hemochromatosis were treated with SnPP and 4 healthy volunteers with SnMP. In all cases, serum ferritin levels increased substantially but transiently after administration of these HO inhibitors. Values returned to baseline within a few days. Infusion of hematin in 4 healthy volunteers did not significantly affect ferritin levels. No increases occurred in 7 other acute-phase reactants. The observation that these HO inhibitors transiently increase serum ferritin levels implies a link between ferritin, iron metabolism and HO activity which may be usefully explored in disorders of iron metabolism.