Update on the role of triglycerides as a risk factor for coronary heart disease

Elevated triglyceride levels represent an independent risk factor for coronary heart disease, and recently the National Cholesterol Education Program revised the acceptable level of fasting triglycerides from less than 200 mg/dL to below 150 mg/dL. However, a sizeable proportion of people in Western societies has persistently elevated triglyceride levels. Fortunately, hygienic and pharmacologic measures can have a considerable impact on reducing triglyceride levels. However, an important yet unanswered question is whether decreasing triglycerides beyond low-density lipoprotein cholesterol lowering contributes significantly to additional coronary heart disease event reduction.

Lack of association between increased carotid intima-media thickening and decreased HDL-cholesterol in a family with a novel ABCA1 variant, G2265T

Low HDL-cholesterol (HDL-C) concentrations are inversely correlated with cardiovascular disease, and previous studies have demonstrated that variants in the ATP-binding cassette transporter, ABCA1, are responsible for a proportion of HDL-C deficiency states. We identified a novel variant in ABCA1 in a kindred with decreased HDL-C. This variant was not identified in >200 chromosomes of healthy individuals. The proband, a heterozygote for G2265T, developed premature coronary artery disease. In addition to low HDL-C, six biological family members heterozygous for the ABCA1 variant exhibited low HDL-C concentrations compared with unaffected family members (0.83 +/- 0.32 vs 1.33 +/- 0.36 mmol/L; P = 0.009). Despite the decreased HDL-C, carotid artery B-mode ultrasound studies failed to reveal increased intima-media thickening in affected individuals compared with age- and sex-matched controls. Although these data extend previous observations that a single defective ABCA1 allele may lead to decreased HDL-C, associated evidence of early atherosclerosis was not confirmed.

Lack of Association between Increased Carotid Intima-Media Thickening and Decreased HDL-Cholesterol in a Family with a Novel ABCA1 Variant, G2265T

Low HDL-cholesterol (HDL-C) concentrations are inversely correlated with cardiovascular disease, and previous studies have demonstrated that variants in the ATP-binding cassette transporter, ABCA1, are responsible for a proportion of HDL-C deficiency states. We identified a novel variant in ABCA1 in a kindred with decreased HDL-C. This variant was not identified in >200 chromosomes of healthy individuals. The proband, a heterozygote for G2265T, developed premature coronary artery disease. In addition to low HDL-C, six biological family members heterozygous for the ABCA1 variant exhibited low HDL-C concentrations compared with unaffected family members (0.83 ± 0.32 vs 1.33 ± 0.36 mmol/L; P = 0.009). Despite the decreased HDL-C, carotid artery B-mode ultrasound studies failed to reveal increased intima-media thickening in affected individuals compared with age- and sex-matched controls. Although these data extend previous observations that a single defective ABCA1 allele may lead to decreased HDL-C, associated evidence of early atherosclerosis was not confirmed.

[Atherosclerosis in HIV-positive patients]

Worldwide, human immunodeficiency virus (HIV) infection is one of the main health subjects. Even, the human immunodeficiency virus primarily effects the immune system, HIV infection also has an impact on other organs. Cardiovascular manifestations in HIV-infected patients could occur by the HI-virus itself or by opportunistic infections. Reports of myocardial infarction in young HIV-infected patients, who received protease inhibitors, have raised concerns about premature arteriosclerosis and coronary artery disease in this population. In the pre-protease inhibitor era, autopsy reports were the first to describe an association between coronary artery disease and HIV infection. Long-term antiretroviral therapy, including protease inhibitors, significantly reduced mortality, morbidity and revolutionized the care of HIV-infected patients. However, class-specific metabolic side effects, such as elevated total cholesterol and triglyceride levels and insulin resistance, have been described. These metabolic alterations of antiretroviral therapy impair the cardiovascular risk profile of HIV-infected patients. Even epidemiological studies found no significant effect of antiretroviral treatment type on coronary heart disease or myocardial infarction, an increase of arteriosclerosis in HIV-infected patients is suspected. Recent results of autopsy studies and analyses of endothelial function in patients with HIV infection described an effect of HIV and antiretroviral therapy on premature arteriosclerosis. The present article gives an overview about arteriosclerosis and coronary events in HIV-infected patients and the impact of antiretroviral therapy.

Cavity solitons as pixels in semiconductor microcavities

Cavity solitons are localized intensity peaks that can form in a homogeneous background of radiation. They are generated by shining laser pulses into optical cavities that contain a nonlinear medium driven by a coherent field (holding beam). The ability to switch cavity solitons on and off and to control their location and motion by applying laser pulses makes them interesting as potential 'pixels' for reconfigurable arrays or all-optical processing units. Theoretical work on cavity solitons has stimulated a variety of experiments in macroscopic cavities and in systems with optical feedback. But for practical devices, it is desirable to generate cavity solitons in semiconductor structures, which would allow fast response and miniaturization. The existence of cavity solitons in semiconductor microcavities has been predicted theoretically, and precursors of cavity solitons have been observed, but clear experimental realization has been hindered by boundary-dependence of the resulting optical patterns-cavity solitons should be self-confined. Here we demonstrate the generation of cavity solitons in vertical cavity semiconductor microresonators that are electrically pumped above transparency but slightly below lasing threshold. We show that the generated optical spots can be written, erased and manipulated as objects independent of each other and of the boundary. Numerical simulations allow for a clearer interpretation of experimental results.

Dioxin exposure is an environmental risk factor for ischemic heart disease

Epidemiologic studies have linked dioxin exposure to increased mortality caused by ischemic heart disease. To test the hypothesis that dioxin exposure may constitute an environmental risk factor for atherosclerosis, we exposed C57BL/6J mice to 5 microg/kg of dioxin daily for 3 d, and measured various molecular and physiological markers of heart disease. Dioxin treatment led to an increase in the urinary excretion of vasoactive eicosanoids and an elevation in the mean tail-cuff blood pressure. In addition, dioxin exposure led to an increase in triglycerides, but not in high-density lipoproteins, in both Apoe(+/+) mice and in hyperlipidemic Apoe(-/- mice. Dioxin exposure also led to an increase in low-density lipoproteins in Apoe(-/-) mice. After treatment, dioxin was associated with low-density lipoprotein particles, which might serve as a vehicle to deliver the compound to atherosclerotic plaques. Dioxin treatment of vascular smooth-muscle cells taken from C57Bl/6J mice resulted in the deregulation of several genes involved in cell proliferation and apoptosis. Subchronic treatment of Apoe(-/-) mice with dioxin (150 ng/kg, three times weekly) for 7 or 26 wk caused a trend toward earlier onset and greater severity of atherosclerotic lesions compared to those of vehicle treated mice. These results suggest that dioxin may increase the incidence of ischemic heart disease by exacerbating its severity.

ABCA1(Alabama): a novel variant associated with HDL deficiency and premature coronary artery disease

The ATP-binding cassette transporter, ABCA1, is a member of the ABC superfamily of proteins involved in the active transport of substrates across cellular membranes. Recent studies have implicated mutations in ABCA1 as the cause of Tangier disease (TD) and familial hypoalphalipoproteinemia (FHA). To evaluate the molecular basis of low high density lipoprotein (HDL) in a family with premature coronary artery disease, single strand conformational polymorphism analysis was performed for all coding regions and splice site junctions of ABCA1 with the genomic DNA of the proband. The proband and affected individuals were heterozygotes for C254T with proline converted to leucine (P85L). This mutation was not identified in over 400 chromosomes of healthy subjects. In the FHA kindred, family members heterozygous for the ABCA1 variant also exhibited corresponding low levels of HDL cholesterol. These data confirm recent data that a single defective allele in ABCA1 may be associated with reduced HDL cholesterol and FHA.

1,3,4-Trisubstituted pyrrolidine CCR5 receptor antagonists. Part 4: Synthesis of N-1 acidic functionality affording analogues with enhanced antiviral activity against HIV

A series of alpha-(pyrrolidin-1-yl)acetic acids is presented as selective and potent antivirals against HIV. Several of the pyrrolidine zwitterions demonstrated reasonable in vitro properties, enhanced antiviral activities and improved pharmacokinetic profiles over pyrrolidine 1.

Clerkship timing and disparity in performance of racial-ethnic minorities in the medicine clerkship

PURPOSE

To determine the effect of the timing of the medicine clerkship on academic performance in different racial-ethnic student groups.

METHOD

Performance was measured by the average assessment of clinical preceptors, an OSCE (objective structured clinical examination), and the NBME (National Board of Medical Examiners) medicine subject examination. Outcomes were analyzed by student racial-ethnicity and clerkship sequence.

RESULTS

Of the 650 students who took the clerkship over four years, 6.9% were African American, 34.6% were Asian-Pacific Islander, 9.1% were Hispanic and 49.4% were white. African American and Hispanic students were in the earliest clerkship sequence 46.7% and 30.5% of the time, respectively, compared to 20% of Asian-Pacific Islanders and 27.4% of white students. Academic performance improved with time and varied among the racial-ethnic groups. All groups achieved higher scores in the NBME medicine examination later in the year but scores of African American and Hispanic students increased to a greater degree than other students.

CONCLUSION

Sometimes, a "few points" on the NBME medicine examination can affect students' final grades and alter their attractiveness to competitive residency training programs. All students, but African American and Hispanic students, in particular, can significantly improve their scores in the NBME medicine examination by taking the clerkship later in the year. Students should be counseled regarding the timing effect and methods to neutralize the disparity should be considered.

Design and implementation of microarray gene expression markup language (MAGE-ML)

BACKGROUND

Meaningful exchange of microarray data is currently difficult because it is rare that published data provide sufficient information depth or are even in the same format from one publication to another. Only when data can be easily exchanged will the entire biological community be able to derive the full benefit from such microarray studies.

RESULTS

To this end we have developed three key ingredients towards standardizing the storage and exchange of microarray data. First, we have created a minimal information for the annotation of a microarray experiment (MIAME)-compliant conceptualization of microarray experiments modeled using the unified modeling language (UML) named MAGE-OM (microarray gene expression object model). Second, we have translated MAGE-OM into an XML-based data format, MAGE-ML, to facilitate the exchange of data. Third, some of us are now using MAGE (or its progenitors) in data production settings. Finally, we have developed a freely available software tool kit (MAGE-STK) that eases the integration of MAGE-ML into end users' systems.

CONCLUSIONS

MAGE will help microarray data producers and users to exchange information by providing a common platform for data exchange, and MAGE-STK will make the adoption of MAGE easier.

High efficiency transgene segregation in co-transformed maize plants using an Agrobacterium tumefaciens 2 T-DNA binary system

For regulatory issues and research purposes it would be desirable to have the ability to segregate transgenes in co-transformed maize. We have developed a highly efficient system to segregate transgenes in maize that was co-transformed using an Agrobacterium tumefaciens 2 T-DNA binary system. Three vector treatments were compared in this study; (1) a 2 T-DNA vector, where the selectable marker gene bar (confers resistance to bialaphos) and the beta-glucuronidase (GUS) reporter gene are on two separate T-DNA's contained on a single binary vector; (2) a mixed strain treatment, where bar and GUS are contained on single T-DNA vectors in two separate Agrobacterium strains; (3) and a single T-DNA binary vector containing both bar and GUS as control treatment. Bialaphos resistant calli were generated from 52 to 59% of inoculated immature embryos depending on treatment. A total of 93.4% of the bialaphos selected calli from the 2 T-DNA vector treatment exhibited GUS activity compared to 11.7% for the mixed strain treatment and 98.2% for the cis control vector treatment. For the 2 T-DNA vector treatment, 86.7% of the bialaphos resistant/GUS active calli produced R0 plants exhibiting both transgenic phenotypes compared to 10% for the mixed strain treatment and 99% for the single T-DNA control vector treatment. A total of 87 Liberty herbicide (contains bialaphos as the active ingredient) resistant/GUS active R0 events from the 2 T-DNA binary vector treatment were evaluated for phenotypic segregation of these traits in the R1 generation. Of these R0 events, 71.4% exhibited segregation of Liberty resistance and GUS activity in the R1 generation. A total of 64.4% of the R0 2 T-DNA vector events produced Liberty sensitive/GUS active (indicating selectable-marker-free) R1 progeny. A high frequency of phenotypic segregation was also observed using the mixed strain approach, but a low frequency of calli producing R0 plants displaying both transgenic phenotypes makes this method less efficient. Molecular analyses were then used to confirm that the observed segregation of R1 phenotypes were highly correlated to genetic segregation of the bar and GUS genes. A high efficiency system to segregate transgenes in co-transformed maize plants has now been demonstrated.

High frequency of human cytomegalovirus (HCMV)-specific CD8+ T cells detected in a healthy CMV-seropositive donor

Human cytomegalovirus (HCMV) persists after infection but is controlled by cellular immune responses, particularly by CD8+ T cells. If infected individuals are immunosuppressed, HCMV can be reactivated. Upon testing the blood of healthy donors with human lymphocyte antigen tetramers, we found one individual with about 50% of his CD8+ T cells being specific for the immunodominant pp65 epitope NLVPMVATV Over a period of 2 years the high level of HCMV-specific T cells was maintained, and no HCMV DNA could be detected. At one timepoint, however, HCMV-specific DNA was detected, while 65% of CD8+ T cells were specific for HCMV. When virus was detectable, a lower percentage of HCMV-specific CD8+ T cells showed interferon gamma (IFN-gamma) production after peptide stimulation in vitro. These data suggest that HCMV reactivation may also occur in immunocompetent persons, accompanied by the presence of HCMV-specific CD8+ T cells which are not producing IFNy, and therefore potentially anergic or in vivo exhausted.

Australian Longitudinal Study of Ageing: prospective evaluation of anthropometric indices in terms of four year mortality in community-living older adults

The Australian Longitudinal Study of Ageing (ALSA) aims to identify factors that contribute to & predict the health & social well-being of older Australians. Analyses were performed to determine the predictive value of anthropometric measurements in older Australians for four-year mortality. Weight, height, skinfolds (triceps, abdominal, supra-spinale, sub-scapular, medial calf, and front thigh) & girth (arm, waist, hip, calf) measurements were performed on a randomly selected community-living sample of 772 men & 624 women aged>70 years. Waist: Hip, % weight loss, corrected-arm-muscle area (CAMA) & BMI were calculated. These measures were categorised into quartiles & also according to commonly adopted definitions of nutritional status. Cox regression analysis was undertaken to assess the predictive value of the independent anthropometric variables for four-year mortality, adjusting for potential confounders (age, gender, marital status, smoking, alcohol status, self-rated health, basic activities of daily living & co-morbidity). Risk of four-year mortality increased with weight loss >10% over two years (HR=2.53, CI=1.37-4.67) & CAMA <21.4cm2(M) & <21.6cm2(F) (HR=1.93, CI=1.03-3.60) independent of confounding variables. These results confirm that selected anthropometric indices (weight loss, CAMA) independently increase the risk of four-year mortality & highlights their potential use in the nutrition screening and assessment of community-living older adults.

Novel ABCA1 compound variant associated with HDL cholesterol deficiency

The recent discovery of an ATP-binding cassette transporter, ABCA1, as an important regulator of high density lipoprotein (HDL) metabolism and reverse cholesterol transport has facilitated the identification of novel variants associated with HDL cholesterol deficiency states. We identified a subject with HDL cholesterol deficiency (4 mg/dl) who developed and died of complications related to cerebral amyloid angiopathy (CAA). The proband had a compound heterozygous mutation. One mutation was a G3295T substitution with conversion of asparagine to tyrosine (D1099Y) in ABCA1. The single-base substitution at codon 1099 resulted in the abolition of an RsaI cleavage site. The proband and affected individuals having another mutation were heterozygotes for T5966C with phenylalanine converted to serine (F2009S). The presence of the T5966C mutation was detected by restriction digestion with HinfI. These variants were not identified in over 400 chromosomes of healthy subjects. In the kindred, family members heterozygous for the ABCA1 variant exhibited low levels of HDL cholesterol. Direct sequencing of all coding regions and splice site junctions of other HDL candidate genes revealed no additional mutations, indicating that combined defective ABCA1 alleles may result in familial HDL deficiency.

Cognitive functioning of long-term heavy cannabis users seeking treatment

CONTEXT

Cognitive impairments are associated with long-term cannabis use, but the parameters of use that contribute to impairments and the nature and endurance of cognitive dysfunction remain uncertain.

OBJECTIVE

To examine the effects of duration of cannabis use on specific areas of cognitive functioning among users seeking treatment for cannabis dependence.

DESIGN, SETTING, AND PARTICIPANTS

Multisite retrospective cross-sectional neuropsychological study conducted in the United States (Seattle, Wash; Farmington, Conn; and Miami, Fla) between 1997 and 2000 among 102 near-daily cannabis users (51 long-term users: mean, 23.9 years of use; 51 shorter-term users: mean, 10.2 years of use) compared with 33 nonuser controls.

MAIN OUTCOME MEASURES

Measures from 9 standard neuropsychological tests that assessed attention, memory, and executive functioning, and were administered prior to entry to a treatment program and following a median 17-hour abstinence.

RESULTS

Long-term cannabis users performed significantly less well than shorter-term users and controls on tests of memory and attention. On the Rey Auditory Verbal Learning Test, long-term users recalled significantly fewer words than either shorter-term users (P =.001) or controls (P =.005); there was no difference between shorter-term users and controls. Long-term users showed impaired learning (P =.007), retention (P =.003), and retrieval (P =.002) compared with controls. Both user groups performed poorly on a time estimation task (P<.001 vs controls). Performance measures often correlated significantly with the duration of cannabis use, being worse with increasing years of use, but were unrelated to withdrawal symptoms and persisted after controlling for recent cannabis use and other drug use.

CONCLUSIONS

These results confirm that long-term heavy cannabis users show impairments in memory and attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis use.

CCR5 antagonists: bicyclic isoxazolidines as conformationally constrained N-1-substituted pyrrolidines

A series of CCR5 antagonists containing bicyclic isoxazolidines was generated through a nitrone mediated cycloaddition with olefins bearing the preferred pharmacophores previously described. Potent antagonists (3 and 16) were generated with enhanced affinity for the CCR5 receptor while maintaining antiviral activity against HIV.