Correlates of non-adherence to antiretroviral therapy in a cohort of HIV-positive drug users receiving antiretroviral therapy in Hanoi, Vietnam

The HIV epidemic in Vietnam is concentrated, with high prevalence estimates among injection drug users and commercial sex workers. Socio-demographics, substance use and clinical correlates of antiretroviral therapy non-adherence were studied in 100 HIV-1 infected drug users receiving antiretroviral therapy for at least 6 months in Hanoi, Vietnam. All study participants were men with a mean age of 29.9 ± 4.9 years. The median duration on antiretroviral therapy was 16.2 ± 12.7 months; 83% reported 'very good' or 'perfect' adherence in the past 30 days on a subjective one-item Likert scale at time of study enrollment; 48% of participants reported drug use within the previous 6 months, with 22% reporting current drug use. Injection drug use with or without non-injection drug use in the past 6 months (95% C.I. 2.19, 1.30-3.69) and years on antiretroviral therapy (95% C.I. 1.43, 1.14-1.78) were correlated with suboptimal adherence. These findings support Vietnam's ongoing scale-up of harm reduction programmes for injection drug users and their integration with antiretroviral therapy delivery. Moreover, results highlight the need to identify and implement new ways to support high levels of antiretroviral therapy adherence as duration on antiretroviral therapy increases.

Color and scent: how single genes influence pollinator attraction

A major function of angiosperm flowers is the recruitment of animal pollinators that serve to transfer pollen among conspecific plants. Distinct sets of floral characteristics, called pollination syndromes, are correlated with visitation by specific groups of pollinators. Switches among pollination syndromes have occurred in many plant families. Such switches must have involved coordinated changes in multiple traits and multiple genes. Two well-studied floral traits affecting pollinator attraction are petal color and scent production. We review current knowledge about the biosynthetic pathways for floral color and scent production and their interaction at the genetic and biochemical levels. A key question in the field concerns the genes that underlie natural variation in color and scent and how such genes affect pollinator preference, reproductive isolation, and ultimately speciation.

Correlates of HIV-1 viral suppression in a cohort of HIV-positive drug users receiving antiretroviral therapy in Hanoi, Vietnam

Injection drug users bear the burden of HIV in Vietnam and are a focus of national treatment programmes. To date, determinants of successful therapy in this population are unknown. Substance use and clinical correlates of viral suppression were studied in 100 HIV-1-infected drug users receiving antiretroviral therapy (ART) for at least six months in Hanoi, Vietnam. The mean age of the cohort was 29.9 + 4.9 years; all were men. A majority of patients (73%) achieved viral suppression (HIV-RNA <1000 copies/mL). Correlates of viral suppression include self-reported > or = 95% adherence (P < 0.01) and current use of trimethoprim/sulphamethoxazole (P < 0.01); current or ever diagnosed with tuberculosis was associated with viral non-suppression (P = 0.006). Tobacco use was prevalent (84%), and surprisingly 48% of patients reported active drug use; neither was associated with viral non-suppression. This is the first study to document successful ART treatment in a population of Vietnamese drug users; rates of viral suppression are comparable to other international populations. The 28% of patients without HIV-1 suppression highlight the need for adherence promotion, risk reduction programmes, and population-based surveillance strategies for assessing the emergence of HIV drug resistance in settings where access to viral load and drug resistance testing is limited.

Analysis of the relation between stent implantation pressure and expansion. Optimal Stent Implantation (OSTI) Investigators

Palmaz-Schatz stents were implanted in 79 lesions in 76 patients, and serially expanded at 12, 15, and 18 atm of pressure using noncompliant balloons. By core lab analysis, intravascular ultrasound demonstrated marked stent expansion as pressure was raised, which was not apparent by angiography.

Regression of nifedipine-induced gingival hyperplasia following switch to a same class calcium channel blocker, isradipine

Patients with nifedipine-induced gingival hyperplasia (GH) often require continued calcium channel blocker therapy. Switches to diltiazem and verapamil have been described; however, these drugs are of a different chemical class and present therapeutic limitations in some patients. The purpose of this study was to evaluate the effect on nifedipine-induced GH of a switch to a dihydropyridine derivative with a low incidence of GH. Fourteen patients with nifedipine-induced GH were given a medical exam and a periodontal exam. The following parameters were assessed: probing depth (PD), gingival margin (GM), gingival thickness (GT), plaque index (PI), and gingival index (GI). Intraoral photographs, study models, and a gingival biopsy for histological examination were taken. Following baseline measures, patients were randomized to continued treatment with nifedipine or an equivalent dose of isradipine in a single-blind fashion. Biweekly periodontal parameters were taken for 8 weeks. At the end of 8 weeks, some patients elected to receive 4 weeks of open label isradipine therapy, with biweekly examination continuing through the open label phase. The isradipine treatment arm showed a mean decrease in PD of 0.59 mm at week 8 (P < 0.05). No other measured parameter (GM, GT, PI, GI) was significantly changed, compared either to baseline or to the alternate treatment arm. Clinically, 60% of patients treated with isradipine exhibited a decrease in hyperplasia, while 66% of patients treated with nifedipine demonstrated an increase in hyperplasia, a significant difference (P < 0.05). When combined with open label data, patients switching therapy to isradipine exhibited an increase in GM (increase in recession) of 0.74 mm from baseline to week 12 (P < 0.05). No patients treated with isradipine exhibited an increase in gingival overgrowth. All patients exhibited adequate control of hypertension. We conclude that in hypertensive patients with nifedipine-induced GH, switching hypertensive therapy to isradipine may result in a regression of GH. When coupled with aggressive oral hygiene treatment, this drug may provide a reasonable option for patients requiring dihydropyridine treatment.

Improved procedural results of coronary angioplasty with intravascular ultrasound-guided balloon sizing: the CLOUT Pilot Trial. Clinical Outcomes With Ultrasound Trial (CLOUT) Investigators

BACKGROUND

Indiscriminate use of balloons larger than the angiographic reference segment lumen results in high rates of ischemic complications after percutaneous transluminal coronary angioplasty (PTCA). We hypothesized that angiographically unsuspected atheromatous remodeling with vessel expansion (the Glagov phenomenon) at and adjacent to PTCA target lesions would safely accommodate oversized balloons in selected patients undergoing PTCA with intravascular ultrasound (IVUS) guidance.

METHODS AND RESULTS

After angiographically guided PTCA of 104 lesions in 102 patients, IVUS was performed, and if atheromatous remodeling was present, PTCA was repeated with larger balloons sized halfway between the lumen and external elastic membrane. Plaque occupied a mean of 51+/-15% of the angiographically "normal" reference segments. Further balloon upsizing by 0.25 to 1.25 mm was therefore performed in 76 lesions (73%), increasing the nominal balloon-to-artery ratio from 1.12+/-0.15 after standard PTCA to 1.30+/-0.17 after IVUS-guided PTCA (P<.0001). As a result, the angiographic minimal luminal diameter further increased from 1.95+/-0.49 to 2.21+/-0.47 mm, the % diameter stenosis fell from 28+/-15% to 18+/-14%, and the IVUS lumen area rose from 3.16+/-1.04 to 4.52+/-1.14 mm2 (all P<.0001). The incidence of angiographic dissection was not increased after IVUS-guided balloon upsizing (37% versus 40%, P=.67), and major complications occurred in only 2 patients (1.9%).

CONCLUSIONS

The demonstration by IVUS of atheromatous remodeling permits the safe use of balloons traditionally considered oversized, resulting in significantly improved luminal dimensions without increased rates of dissection or ischemic complications.

Correlation of intracoronary ultrasound plaque characteristics in atherosclerotic coronary artery disease patients with clinical variables

It was examined whether intracoronary ultrasound-defined plaque morphology of symptom-producing, severely stenosed, atherosclerotic coronary artery lesions is related to patient-related clinical variables. Data regarding anginal pattern (stable vs unstable), age, sex, history of smoking, diabetes, hypertension, hypercholesterolemia and lesion location were recorded in 146 hemodynamically stable patients referred for clinically indicated balloon angioplasty or directional atherectomy. Intracoronary ultrasound images of the lesions were obtained before and after the intervention. Lesions were classified as soft (homogeneous echoes less dense than adventitia) or hard (bright echoes with or without acoustic shadowing). Eighty-three lesions (57%) were classified as soft and 63 (43%) as hard. Univariate analysis showed anginal pattern, age, vessel location and history of smoking to be significantly related to plaque morphology. Multivariate analysis revealed only anginal pattern, age and vessel location to be independent predictors of plaque morphology. The frequency of echogenic hard plaque was significantly higher in patients aged > 60 years (56 vs 30%; p = 0.001), those with stable angina (69 vs 35%; p = 0.002), and lesions located in the distal arterial segments (68 vs 31%; p < 0.001) than in younger ones, those with unstable angina, and lesions in proximal segments, respectively. Based on previous studies, echogenic hard plaques are likely to be predominantly fibrous or calcific, or both, whereas low-echogenicity soft plaques are likely to be fibrocellular, lipid rich or thrombotic, or a combination. This difference in plaque morphology is probably due to differences in the predominant mechanism of plaque formation (i.e., slow growth vs rupture/thrombosis).(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous intravascular ultrasound imaging: validation of a real-time synthetic aperture array catheter

This study was designed to validate the dimensional accuracy and ability to characterize atherosclerotic vessel morphology of a new percutaneously passed ultrasound catheter. The 5.5F catheter used for this study has a synthetic aperture array transducer providing a radial field of view perpendicular to the catheter and can be passed over a standard 0.014-in guide wire. Initial in vitro studies were performed to assess accuracy of dimensional and morphologic information. In vitro images of fixed human vessels demonstrated good boundary definition, and dimensional measurements were closely correlated with histological samples (luminal area, r = .97; maximal lumen diameter, r = .95; maximal wall thickness, r = .83). Morphological subtypes were also closely correlated, with increasing severity of histological atherosclerosis characterized by predictable changes in the ultrasound images. Subsequently, the catheter was passed percutaneously in 28 patients to obtain images of coronary (n = 20) and pelvic (n = 12) vessels. Ultrasound images were compared with simultaneous digital angiograms. Correlation between ultrasonic and angiographic estimations of vessel diameters was good (r = .92). We conclude that intravascular ultrasound imaging will be useful for dimensional and morphological characterization of vascular disease, for the study of regression or progression of atherosclerosis, and, potentially, for guidance of therapeutic interventions such as atherectomy and angioplasty.

Sexual function after heart transplantation

To define sexual interest, ability, and activity before and after heart transplantation, we surveyed all discharged, male heart transplant recipients from our institution. Of the 115 potential subjects, 71 (62%) responded. Respondents were predominantly (89%) white, had a mean age of 47.9 years (24 to 64 years), and most (74%) were living with their spouses. Pretransplant libido was strong and remained unchanged after heart transplantation. Transplant recipients reported their partner's libido to be strong, and even stronger after transplantation than before (p = 0.033). In contrast, erectile rigidity and orgasmic ability were impaired before, and declined further after, the transplant procedure. Respondents perceived this gap between libido and sexual ability to be a problem, and interest in evaluation and treatment was high.

Investigation of the properties of bovine heart creatine kinase cross-linked with dimethyl suberimidate

Dimeric bovine heart creatine kinase (EC 2.7.3.2, ATP: creatine N-phosphotransferase) has been cross-linked with the bifunctional reagent dimethyl suberimidate at several concentrations to yield modified enzyme with enhanced stability towards heat denaturation. The degree of thermal stability is dependent on the degree of cross-linking with optimal stabilization occurring when approx. half of all the available amino groups are covalently attached to dimethyl suberimidate. Accelerated storage studies were performed and the results used to predict the storage time of the native and modified enzyme at lower temperatures. The cross-linked derivative was predicted to have a longer shelf-life at 4 degrees C than the native enzyme. Modification caused a reduction in the specific activity of the enzyme. The pH profile was altered following cross-linking, but the Michaelis constants were not changed. The modified enzyme exhibited a marked resistance to the action of some denaturing agents.

Arrhythmias in patients with CHF. Should they be treated?

Ventricular arrhythmias are a major cause of death in patients with congestive heart failure. Dr Ellenbogen and his associates discuss the current thinking, based on recent studies, concerning use of antiarrhythmic agents to prevent sudden cardiac death in these patients. As they point out, the proper antiarrhythmic therapy may be crucial to long-term survival.

Percutaneous intracoronary ultrasound imaging: initial applications in patients

This study was designed to evaluate the feasibility and potential clinical utility of intracoronary ultrasound imaging in patients using a 5.5 F synthetic aperture array, over-a-wire ultrasound catheter. Thirty patients underwent percutaneous intracoronary (n = 22) or peripheral (n = 8) ultrasound imaging at the time of cardiac catheterization. Ultrasound images were compared to simultaneous digital angiograms. Correlation between ultrasonic and angiographic estimation of coronary diameters was good (r = 0.80). Morphological analysis of ultrasound images obtained in patients revealed a pattern consistent with mild-to-minimal atherosclerosis, as defined by prior in vitro studies. In 15 patients, imaging was performed during intracoronary infusion of vasoactive medications (papaverine 15 mg, nitroglycerine 100 mugm, and acetylcholine 2 x 10 -5 or 2 x 10 -6M). These medications were also infused during continuous intracoronary Doppler catheter monitoring of velocity and pressure, thus allowing calculation of volume flow and coronary resistance indices. Serial determination of ultrasound-derived epicardial vessel cross-sectional area demonstrated no change (-1 +/- 1%) after papaverine, an 8 +/- 2% increase after nitroglycerine, and a 9 +/- 3% decrease after acetylcholine. Calculated resistance fell 53 +/- 4% after acetylcholine and 60 +/- 3% after papaverine. Preliminary in vitro studies using a combination angioplasty balloon/ultrasound catheter demonstrated the ability to visualize vessel dilation in real time. We conclude that intravascular ultrasound imaging will be useful for dimensional and morphological characterization of vascular disease, for beat-to-beat monitoring of vasomotion, and potentially as a real-time adjunct to therapeutic interventions.

Electrophysiological effects of adenosine in the transplanted human heart. Evidence of supersensitivity

After cardiac transplantation, the denervated donor atria and ventricles demonstrate increased sensitivity to infusions of sympathomimetic amines. Recently, supersensitivity of the canine sinus and atrioventricular (AV) nodes to acetylcholine has also been demonstrated after parasympathetic denervation. Acetylcholine and the endogenous nucleoside adenosine exert similar electrophysiological effects in both the sinus and AV nodes, and share a common transduction process. We, therefore, hypothesized that after orthotopic cardiac transplantation, the donor (denervated) sinus node would demonstrate greater sensitivity to exogenous adenosine than the recipient (innervated) sinus node. The effects of incremental doses of intravenous adenosine (37-112 micrograms/kg) on changes in sinus cycle length (SCL) (delta SCLmax%), changes in PR interval (delta PRmax%), time to peak effect (sec), and duration of electrophysiological effects (sec) were prospectively measured in 28 orthotopic cardiac transplant patients and nine control subjects. The baseline SCL was 795 +/- 71 msec for the control subjects, 891 +/- 43 msec for the recipient atria, and 700 +/- 18 msec for the donor atria (p less than 0.05, donor vs. recipient). The delta SCLmax% for each dose of adenosine was similar in the innervated control and recipient atria. In contrast, the donor sinus node demonstrated a threefold to fourfold increased response to adenosine as compared with the recipient sinus node and a threefold to sixfold increased response as compared with control subjects. Similarly, the donor AV node demonstrated a threefold to fivefold increase in PR interval as compared with control subjects. The duration of sinus node slowing in the denervated atria was threefold to fivefold longer than in the recipient and control atria (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical percutaneous imaging of coronary anatomy using an over-the-wire ultrasound catheter system

This manuscript describes initial applications of a unique new intravascular ultrasound imaging catheter. This 5.5F catheter uses an over-the-wire design and incorporates a phased array transducer at its tip. There are no moving parts. A 360 degree image is produced perpendicular to the catheter axis using a 20 MHz center frequency. A dedicated minicomputer is used for initial image processing, as well as enhancement and analysis. Initial studies using phantoms demonstrated excellent accuracy for linear dimensions (r = 0.99, range 3.0 to 7.6 mm, image = 1.0 phantom + 0.1). Serial imaging of the same arterial segment in vitro showed good reproducibility (coefficients of variance 2.5-5.2%). Likewise, intra- and inter-observer variability in image analysis was minimal (r = 0.92-0.99). Initial in vivo studies were performed in dogs. The catheter was easily passed over a wire into mesenteric, cerebral and coronary vessels without evidence of significant vessel trauma. Subsequently, 20 patients had percutaneous coronary imaging performed during cardiac catheterization. Cardiac motion was rarely a problem and acceptable images were obtained in all but two patients. Areas of calcification, mild stenoses, branching vessels and graft atherosclerosis could be identified. We conclude that intracoronary ultrasound imaging will be useful for assessing vascular pathology, for studying both rapid change in vessel size as well as chronic progression or regression of atherosclerosis, and for assisting with new therapeutic interventions.