Solving the IRAK-4 enigma: application of kinase-dead knock-in mice

Interleukin-1 receptor-associated kinase (IRAK-4) is an essential component of the signal transduction complex downstream of the interleukin (IL)-1- and Toll-like receptors. Though regarded as the first kinase in the signaling cascade, the role of IRAK-4 kinase activity versus its scaffold function has been controversial. In order to investigate the role of IRAK-4 kinase function in vivo, we generated "knock-in" mice where the wild-type IRAK-4 gene is replaced with a mutant gene encoding kinase-deficient IRAK-4 protein (IRAK-4 KD). IRAK-4 kinase is rendered inactive by mutating the conserved lysine residues in the ATP pocket essential for coordinating ATP. Analyses of embryonic fibroblasts and macrophages obtained from IRAK-4 KD mice demonstrated lack of cellular responsiveness to stimulation with IL-1beta or Toll-like receptor 4 (TLR4) and TLR7 agonists. IRAK-4 KD cells were severely impaired in NF-kappaB, JNK, and p38 activation in response to IL-1beta or TLR7 ligand. In addition, activation of JNK and p38 was affected in lipopolysaccharide (LPS)-stimulated IRAK-4 KD macrophages. As a consequence, IL-1 receptor/TLR4/TLR7-mediated production of cytokines and chemokines was largely absent in these cells. Additionally, microarray analysis identified IL-1beta response genes and revealed that the induction of IL-1beta-responsive mRNAs is largely ablated in IRAK-4 KD cells. In summary, our results suggest that IRAK-4 kinase activity plays a critical role in IL-1R-, TLR4-, and TLR7-mediated induction of inflammatory responses.

Co-occurrence of autoimmune thyroid disease in a multiple sclerosis cohort

Background

Multiple sclerosis (MS), Hashimoto's disease and Graves' disease are autoimmune diseases that may share similar pathogenic mechanisms. The co-occurrence rates and demographic characteristics of Graves' disease and Hashimoto's disease (HT) in our MS population are compared with the general population.

Methods

The prevalence of thyroid disease in our MS patients was determined by chart review and survey. Previous diagnosis of thyroid disease, age at diagnosis, treatment used, and about the use of disease modifying medications used to treat their MS were asked. Chart reviews were used to estimate the population prevalence of Graves' disease and Hashimoto's disease and to estimate the demographics of patients with thyroid disease.

Results

A significant co-occurrence of Graves' disease with MS (p = 0.002), and a non-significant co-occurrence of Hashimoto's disease were noted (p = 0.097). No difference in the age of onset or gender of thyroid disease in MS patients compared to the general population was found.

Conclusion

There is a significant co-occurrence in patients with MS and Graves' disease, and a trend to co-occurrence in patients with MS and Hashimoto's disease. There are no differences in the demographics of patients with thyroid disease in our MS patients compared to the general population.

Pre-prandial vs. post-prandial capillary glucose measurements as targets for repaglinide dose titration in people with diet-treated or metformin-treated Type 2 diabetes: a randomized controlled clinical trial

OBJECTIVE

Repaglinide is an oral anti-diabetic agent that has a short duration of action, and is suitable for preventing post-prandial rises in glucose levels. Targeting post-prandial glucose levels may lead to lower HbA(1c) levels and rates of hypoglycaemia than targeting pre-prandial glucose levels.

RESEARCH DESIGN AND METHODS

In 42 centres, 193 drug-naive (n = 122) or metformin-treated (n = 71) individuals with Type 2 diabetes were randomly allocated to a 40-day period of repaglinide dose-titration (starting at 0.5 mg three times daily) based on either self-measured pre-prandial or post-prandial glucose levels. They were followed for a further 12 weeks and HbA(1c) and hypoglycaemia rates were recorded.

RESULTS

Repaglinide reduced HbA(1c) by 1.25 and 1.07% in the post-prandial and pre-prandial groups, respectively (P for difference = 0.6), and achieved target glucose levels in 80.7 and 66.7%, respectively (P = 0.16). The effect of titration strategy differed by baseline drug therapy, and was more effective in the metformin-treated individuals who experienced a HbA(1c) fall of 0.6 vs. 1.10% with pre-prandial vs. post-prandial titration (P for metformin-allocated group interaction = 0.043). The rate of hypoglycaemia did not differ by group.

CONCLUSIONS

In drug-naive individuals with Type 2 diabetes, similar HbA(1c) levels are achieved with repaglinide when dosing is adjusted according to either post-prandial or pre-prandial levels. Conversely, in metformin-treated individuals, repaglinide dosing according to post-prandial levels may lead to better glycaemic control than dosing according to pre-prandial levels.

The association between osteoporotic fractures and health-related quality of life as measured by the Health Utilities Index in the Canadian Multicentre Osteoporosis Study (CaMos)

Osteoporotic fractures can be a major cause of morbidity. It is important to determine the impact of fractures on health-related quality of life (HRQL). A total of 3,394 women and 1,122 men 50 years of age and older, who were recruited for the Canadian Multicentre Osteoporosis Study (CaMos), participated in this cross-sectional study. Minimal trauma fractures of the hip, pelvis, spine, lower body (included upper and lower leg, knee, ankle, and foot), upper body (included arm, elbow, sternum, shoulder, and clavicle), wrist and hand (included forearm, hand, and finger), and ribs were studied. Participants with subclinical vertebral deformities were also examined. The Health Utilities Index Mark II and III Systems were used to assess HRQL. Past osteoporotic fractures varied in prevalence from 1.2% (pelvis) to 27.8% (lower body) in women and 0.3% (pelvis) to 29.3% (wrist) in men. Multivariate linear regression analyses [parameter estimates and corresponding 95% confidence intervals (CI)] indicated that minimal trauma fractures were negatively associated with HRQL and that this relationship depends on fracture type and gender. The multi-attribute scores for the Mark II system were negatively related to hip (-0.05; 95% CI: -0.09, -0.01), lower body (-0.02; 95% CI: -0.03, -0.000), and subclinical vertebral fractures (-0.02; 95% CI: -0.03, -0.00) for women. The multi-attribute scores for the Mark III system were negatively related to hip (-0.09; 95% CI: -0.14, -0.03) and rib fractures (-0.06; 95% CI: -0.11, -0.00) for women, and rib fractures (-0.06; 95% CI: -0.12, -0.00) for men. In conclusion, this study demonstrates a negative association between osteoporotic fractures and quality of life in both women and men.

Associations among disease conditions, bone mineral density, and prevalent vertebral deformities in men and women 50 years of age and older: cross-sectional results from the Canadian Multicentre Osteoporosis Study

This cross-sectional cohort study of 5566 women and 2187 men 50 years of age and older in the population-based Canadian Multicentre Osteoporosis Study was conducted to determine whether reported past diseases are associated with bone mineral density or prevalent vertebral deformities. We examined 12 self-reported disease conditions including diabetes mellitus (types 1 or 2), nephrolithiasis, hypertension, heart attack, rheumatoid arthritis, thyroid disease, breast cancer, inflammatory bowel disease, neuromuscular disease, Paget's disease, and chronic obstructive pulmonary disease. Multivariate linear and logistic regression analyses were performed to determine whether there were associations among these disease conditions and bone mineral density of the lumbar spine, femoral neck, and trochanter, as well as prevalent vertebral deformities. Bone mineral density measurements were higher in women and men with type 2 diabetes compared with those without after appropriate adjustments. The differences were most notable at the lumbar spine (+0.053 g/cm2), femoral neck (+0.028 g/cm2), and trochanter (+0.025 g/cm2) in women, and at the femoral neck (+0.025 g/cm2) in men. Hypertension was also associated with higher bone mineral density measurements for both women and men. The differences were most pronounced at the lumbar spine (+0.022 g/cm2) and femoral neck (+0.007 g/cm2) in women and at the lumbar spine (+0.028 g/cm2) in men. Although results were statistically inconclusive, men reporting versus not reporting past nephrolithiasis appeared to have clinically relevant lower bone mineral density values. Bone mineral density differences were -0.022, -0.015, and -0.016 g/cm2 at the lumbar spine, femoral neck, and trochanter, respectively. Disease conditions were not strongly associated with vertebral deformities. In summary, these cross-sectional population-based data show that type 2 diabetes and hypertension are associated with higher bone mineral density in women and men, and nephrolithiasis may be associated with lower bone mineral density in men. The importance of these associations for osteoporosis case finding and management require further and prospective studies.

ABCA1 overexpression leads to hyperalphalipoproteinemia and increased biliary cholesterol excretion in transgenic mice

The discovery of the ABCA1 lipid transporter has generated interest in modulating human plasma HDL levels and atherogenic risk by enhancing ABCA1 gene expression. To determine if increased ABCA1 expression modulates HDL metabolism in vivo, we generated transgenic mice that overexpress human ABCA1 (hABCA1-Tg). Hepatic and macrophage expression of hABCA1 enhanced macrophage cholesterol efflux to apoA-I; increased plasma cholesterol, cholesteryl esters (CEs), free cholesterol, phospholipids, HDL cholesterol, and apoA-I and apoB levels; and led to the accumulation of apoE-rich HDL1. ABCA1 transgene expression delayed 125I-apoA-I catabolism in both liver and kidney, leading to increased plasma apoA-I levels, but had no effect on apoB secretion after infusion of Triton WR1339. Although the plasma clearance of HDL-CE was not significantly altered in hABCA1-Tg mice, the net hepatic delivery of exogenous 3H-CEt-HDL, which is dependent on the HDL pool size, was increased 1.5-fold. In addition, the cholesterol and phospholipid concentrations in hABCA1-Tg bile were increased 1.8-fold. These studies show that steady-state overexpression of ABCA1 in vivo (a) raises plasma apoB levels without altering apoB secretion and (b) raises plasma HDL-C and apoA-I levels, facilitating hepatic reverse cholesterol transport and biliary cholesterol excretion. Similar metabolic changes may modify atherogenic risk in humans.

Albuminuria and risk of cardiovascular events, death, and heart failure in diabetic and nondiabetic individuals

CONTEXT

Microalbuminuria is a risk factor for cardiovascular (CV) events. The relationship between the degree of albuminuria and CV risk is unclear.

OBJECTIVES

To estimate the risk of CV events in high-risk individuals with diabetes mellitus (DM) and without DM who have microalbuminuria and to determine whether levels of albuminuria below the microalbuminuria threshold increase CV risk.

DESIGN

The Heart Outcomes Prevention Evaluation study, a cohort study conducted between 1994 and 1999 with a median 4.5 years of follow-up.

SETTING

Community and academic practices in North and South America and Europe.

PARTICIPANTS

Individuals aged 55 years or more with a history of CV disease (n = 5545) or DM and at least 1 CV risk factor (n = 3498) and a baseline urine albumin/creatinine ratio (ACR) measurement.

MAIN OUTCOME MEASURES

Cardiovascular events (myocardial infarction, stroke, or CV death); all-cause death; and hospitalization for congestive heart failure.

RESULTS

Microalbuminuria was detected in 1140 (32.6%) of those with DM and 823 (14.8%) of those without DM at baseline. Microalbuminuria increased the adjusted relative risk (RR) of major CV events (RR, 1.83; 95% confidence interval [CI], 1.64-2.05), all-cause death (RR, 2.09; 95% CI, 1.84-2.38), and hospitalization for congestive heart failure (RR, 3.23; 95% CI, 2.54-4.10). Similar RRs were seen for participants with or without DM, even after adjusting for other CV risk factors (eg, the adjusted RR of the primary aggregate end point was 1.97 [95% CI, 1.68-2.31] in those with DM and 1.61 [95% CI, 1.36-1.90] in those without DM). Compared with the lowest quartile of ACR (<0.22 mg/mmol), the RRs of the primary aggregate end point in the second quartile (ie, ACR range, 0.22-0.57 mg/mmol) was 1.11 (95% CI, 0.95-1.30); third quartile, 1.38 (95% CI, 1.19-1.60; ACR range, 0.58-1.62 mg/mmol); and fourth quartile, 1.97 (95% CI, 1.73-2.25; ACR range, >1.62 mg/mmol) (P for trend <.001, even after excluding those with microalbuminuria). For every 0.4-mg/mmol increase in ACR level, the adjusted hazard of major CV events increased by 5.9% (95% CI, 4.9%-7.0%).

CONCLUSIONS

Our results indicate that any degree of albuminuria is a risk factor for CV events in individuals with or without DM; the risk increases with the ACR, starting well below the microalbuminuria cutoff. Screening for albuminuria identifies people at high risk for CV events.

ABCA1 overexpression leads to hyperalphalipoproteinemia and increased biliary cholesterol excretion in transgenic mice

The discovery of the ABCA1 lipid transporter has generated interest in modulating human plasma HDL levels and atherogenic risk by enhancing ABCA1 gene expression. To determine if increased ABCA1 expression modulates HDL metabolism in vivo, we generated transgenic mice that overexpress human ABCA1 (hABCA1-Tg). Hepatic and macrophage expression of hABCA1 enhanced macrophage cholesterol efflux to apoA-I; increased plasma cholesterol, cholesteryl esters (CEs), free cholesterol, phospholipids, HDL cholesterol, and apoA-I and apoB levels; and led to the accumulation of apoE-rich HDL1. ABCA1 transgene expression delayed 125I-apoA-I catabolism in both liver and kidney, leading to increased plasma apoA-I levels, but had no effect on apoB secretion after infusion of Triton WR1339. Although the plasma clearance of HDL-CE was not significantly altered in hABCA1-Tg mice, the net hepatic delivery of exogenous 3H-CEt-HDL, which is dependent on the HDL pool size, was increased 1.5-fold. In addition, the cholesterol and phospholipid concentrations in hABCA1-Tg bile were increased 1.8-fold. These studies show that steady-state overexpression of ABCA1 in vivo (a) raises plasma apoB levels without altering apoB secretion and (b) raises plasma HDL-C and apoA-I levels, facilitating hepatic reverse cholesterol transport and biliary cholesterol excretion. Similar metabolic changes may modify atherogenic risk in humans.

Rapid-onset dystonia-parkinsonism: a clinical and genetic analysis of a new kindred

BACKGROUND

Rapid-onset dystonia-parkinsonism (RDP) is an autosomal dominant disorder linked to chromosome 19q13 that is characterized by sudden onset of primarily bulbar and upper limb dystonia with parkinsonism.

METHODS

The authors evaluated 12 individuals from three generations of an Irish family and obtained detailed medical records on a deceased member. The authors describe the clinical, psychiatric, and genetic features of the affected individuals.

RESULTS

Five of eight affected members developed sudden-onset (several hours to days) dystonia with postural instability. Four of the five also had bulbar symptoms. Two have stable focal or segmental limb dystonia. One has intermittent hemidystonia with dysarthria that comes on abruptly in times of stress or anxiety. Three had a history of profound difficulty socializing, and at presentation two developed depression. Three patients had a trial of dopamine agonists without benefit. Genetic analysis suggests linkage to chromosome 19 with lod score of 2.1 at zero recombination.

CONCLUSION

This is the third reported family with chromosome 19q13 rapid-onset dystonia-parkinsonism. Psychiatric morbidity appeared common in affected members of this family and may be part of the RDP phenotype.

Prevalence and determinants of microalbuminuria in high-risk diabetic and nondiabetic patients in the Heart Outcomes Prevention Evaluation Study. The HOPE Study Investigators

OBJECTIVE

To describe the characteristics of diabetic and nondiabetic participants in the Heart Outcomes Prevention Evaluation (HOPE) Study who are at high risk of developing cardiovascular (CV) disease and who have microalbuminuria (MA), and to identify the key determinants of MA in these two groups.

RESEARCH DESIGN AND METHODS

Albuminuria was measured in 97% of patients enrolled in the HOPE Study as part of the MICRO-HOPE (MA, CV, and Renal Outcomes in HOPE) substudy. Baseline clinical characteristics of diabetic and nondiabetic participants with MA were recorded, and the univariate and multivariate relationship between these characteristics and the presence of MA was estimated for both groups.

RESULTS

Baseline urinary albumin determinations were available in 3,574 (97.8%) diabetic participants and 5,708 (97.0%) nondiabetic participants. MA was detected in 1,151 (32.2%) diabetic participants and 837 (14.7%) nondiabetic participants. Age, waist-to-hip ratio, diabetes, smoking, hypertension, vascular disease, and left ventricular hypertrophy were independent determinants of MA in all participants. In diabetic participants, the odds of MA increased 16% for every 10.4 years of diabetes duration, and increased 8% for every 0.9% increase in glycated hemoglobin (assuming a GHb assay with an upper limit of 6% in the nondiabetic range).

CONCLUSIONS

MA is independently associated with several risk factors for CV and renal disease in both diabetic and nondiabetic individuals at high risk for CV disease.

Acyl-coenzyme A:cholesteryl acyltransferase 2

In addition to acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1), an enzyme in the endoplasmic reticulum of cells found ubiquitously throughout the body, data recently obtained in at least three mammalian species, including nonhuman primates, mice and humans, demonstrate the presence of an additional ACAT (EC 2.1.3.26), termed ACAT2, which is localized to the endoplasmic reticulum of liver and intestine. Data suggest that ACAT2 may be the enzyme responsible for cholesteryl ester secretion into apolipoprotein B-containing lipoproteins. We have hypothesized that oversecretion of cholesteryl esters produced by the action of hepatic ACAT2 could account for the increased atherogenicity associated with cholesteryl ester-enriched LDL in nonhuman primates. In such cases, ACAT2 is an appealing target for therapy to reduce coronary heart disease.

Hyperinsulinism: molecular aetiology of focal disease

Persistent hypoglycaemia in infancy is most commonly caused by hyperinsulinism. A case is reported of the somatic loss of the maternal 11p in an insulin secreting focal adenoma in association with a germline SUR-1 mutation on the paternal allele in a baby boy with hyperinsulinism diagnosed at 49 days old. A reduction to homozygosity of an SUR-1 mutation is proposed as a critical part of the cause of focal hyperinsulinism.

Identification of a form of acyl-CoA:cholesterol acyltransferase specific to liver and intestine in nonhuman primates

The present study demonstrates that two different forms of the intracellular cholesterol esterification enzyme acyl-CoA:cholesterol acyltransferase (ACAT) are present in the nonhuman primate hepatocyte; one is similar to that originally cloned from human genomic DNA, here termed ACAT1, while a second gene product, termed ACAT2, is reported here. The primate ACAT2 gene product was cloned from an African green monkey liver cDNA library. Sequence analysis of an isolated, full-length clone of ACAT2 cDNA identified an open reading frame encoding a 526-amino acid protein with essentially no sequence similarity to the ACAT1 cDNA over the N-terminal 101 amino acids but with 57% identity predicted over the remaining 425 amino acids. Transfection of the cloned ACAT2 cDNA into two different mammalian cell types resulted in the production of abundant ACAT activity which was sensitive to ACAT inhibitors. Northern blot analysis showed that the ACAT2 mRNA was expressed primarily in liver and intestine in monkeys. In contrast, ACAT1 mRNA was expressed in almost all tissues examined. Topologic predictions from the amino acid sequence of ACAT2 indicates that it has seven trans-membrane domains in a configuration that places the putative active site of the enzyme in the lumen of the endoplasmic reticulum. This orientation of ACAT2 in the endoplasmic reticulum membrane, in addition to its expression only in liver and intestine, suggests that this enzyme may have as a primary function, the secretion of cholesteryl esters into apoB-containing lipoproteins.

Mosaicism for trisomy 3q arising from an unbalanced, de novo t(3;15)

We report on a 2 1/2 year old girl who is dysmorphic, developmentally delayed, and mosaic for an unbalanced, de novo translocation between chromosomes 3 and 15. The karyotype from peripheral blood lymphocytes is 46,XX (50) and the karyotype from skin fibroblasts is 46,XX (28)/46,XX,der(15)t(3;15)(q11;p11) (23). The mechanism for the generation of this unbalanced, de novo translocation is discussed.

Mutation of RET codon 768 is associated with the FMTC phenotype

Multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B), and familial medullary thyroid carcinoma (FMTC) are inherited cancer syndromes resulting from mutations in the RET proto-oncogene. Missense mutations of five codons in exons 10 and 11 are found in both MEN 2A and FMTC families, while mutations at codon 768 in exon 13 have been identified in three FMTC families. We report here the results of mutation analysis on a large multi-generation family with multiple cases of medullary thyroid carcinoma (MTC) or C-cell hyperplasia and two individuals with isolated adrenal medullary hyperplasia. A mutation in exon 13, which alters codon 768 from a GAG (Glu) to a GAC (Asp), was found to segregate with the FMTC phenotype in this family but not with the adrenal medullary hyperplasia. These findings suggest that the codon 768 mutation does not predispose to adrenal medullary hyperplasia, but is an accurate predictor of the MTC phenotype in this family.

Continuing transmission of sexually transmitted diseases among patients infected with HIV-1 attending genitourinary medicine clinics in England and Wales

OBJECTIVE

To determine whether those who are aware of being infected with HIV continue to adopt behaviours that place others at risk of HIV infection.

DESIGN

Ongoing survey of current diagnosis of sexually transmitted disease and awareness of HIV infection among patients attending genitourinary medicine clinics.

SETTING

Six genitourinary medicine clinics in England and Wales (two in London and four outside) participating in unlinked anonymous HIV serosurveillance during 1990-3.

SUBJECTS

All attenders having blood drawn for syphilis serology for the first time during the calendar quarter of attendance.

MAIN OUTCOME MEASURES

The proportion of syphilis serology specimens with antibody to HIV-1 detected by unlinked anonymous testing of the residue. The proportion of attenders infected with HIV-1 who remained clinically undetected, and the proportion who had another recently acquired sexually transmitted disease.

RESULTS

Of 85441 specimens tested, 2328 (2.7%) were positive for antibodies to HIV-1. About 30% of these specimens were from attenders whose HIV-1 infection remained clinically undetected. HIV-1 infection was found to coexist with another recently acquired sexually transmitted disease in 651 attenders, of whom 522 were homosexual or bisexual men. Of these, 245 (47%) already knew themselves to be infected with HIV-1. This proportion increased between 1990 and 1993.

CONCLUSIONS

A considerable proportion of patients infected with HIV-1 are not identified by voluntary confidential HIV testing in genitourinary medicine clinics. Substantial numbers of homosexual or bisexual men attending genitourinary medicine clinics continue to practise unsafe sex despite being aware of their infection with HIV-1.

Detection of the heat-stable toxin coding gene (ST-gene) in enterotoxigenic Escherichia coli: development of a colour amplified PCR detection system

Screening biological samples using the polymerase chain reaction (PCR) has obvious advantages compared with current molecular analytical methods based on gel electrophoresis and/or hybridisation, both of which are expensive and time-consuming, therefore the development of a PCR assay format that is applicable to large sample numbers and that can readily use equipment commonly found in diagnostic laboratories would be advantageous. This report describes the development of a colour amplified PCR detection system which is simple in design and could be universally applied to the detection of any DNA template. As an example, the system has been applied in the detection of the heat-stable toxin coding gene (ST-gene) from enterotoxigenic Escherichia coli (ETEC). The assay is sensitive, detecting 10 fg of a purified DNA template and 270 cfu of an ST-gene-positive ETEC strain.

Permissive hypercapnia in ARDS and its effect on tissue oxygenation

Many experimental studies have shown that mechanical ventilation with high tidal volumes (Vt) or with a low end-expiratory volume allowing repeated end-expiratory collapse, can result in acute parenchymal lung injury and probably an inflammatory response. Low volume ventilation with permissive hypercapnia has been used in an attempt to avoid such injury in ARDS. Such management can affect oxygenation in many complex ways. The right-shift of the haemoglobin-oxygen dissociation curve during acute respiratory acidosis may increase venous oxygen tension (PvO2) which could allow increased O2 uptake in ischaemic tissues. Acidosis may reduce intrapulmonary shunt (Qs/Qt) by potentiating hypoxic pulmonary vasoconstriction, and there may also be direct and autonomically mediated effects of hypercapnia both on the lung vasculature and on the airways. Cardiac output usually increases as a consequence of hypercapnia and perhaps as a result of reduced intrathoracic pressure, further increasing PvO2 and CvO2, but the increase in cardiac output (CO) may tend to increase Qs/Qt as flow increases preferentially in unventilated lung. The reduction of mean airway pressure may directly increase Qs/Qt. Hypercapnia may affect the distribution of systemic blood flow both within organs and between organs. Limited clinical studies suggest that tissue oxygenation is usually unchanged or improved during permissive hypercapnia with increased CO, reduced arterio-venous O2 content difference and reduced blood lactate concentration. However, acute hypercapnia per se can reduce lactate production. Further studies are required of this complex issue.