Ribozymes as anti-HIV-1 therapeutic agents: principles, applications, and problems

An emerging strategy in the treatment of viral infections is the use of antisense DNA or RNA to pair with, and block expression of viral transcripts. RNA, in addition to being an informational molecule, can also possess enzymatic activity. Thus, by combining anti-sense and enzymatic functions into a single transcript, it is now possible to design catalytic RNAs, or ribozymes, which can specifically pair with virtually any viral RNA, and cleave the phosphodiester backbone at a specified location, thereby functionally inactivating the viral RNA. In carrying out this cleavage, the ribozyme is not itself altered, and is thus capable of recycling and cleaving other molecules, making it a true enzyme. There are several different catalytic motifs which possess enzymatic activity, and each one of these can be incorporated into an enzymatic antisense with site-specific cleavage capabilities. By focusing on one type of catalytic motif, the hammerhead, we describe the principles behind the development of ribozymes as transacting, site-specific ribonucleases, several applications of ribozymes in functional destruction of target RNAs, as well as several of the problems confronting their use. We also describe a liposome delivery system which facilitates intracellular inclusion of ribozymes, and may provide a means for therapeutic delivery of ribozymes to HIV-1 infected cells.

DOUBLE-BLIND PLACEBO CONTROLLED STUDY OF α-ADRENERGIC RECEPTOR ANTAGONISTS (DOXAZOSIN) FOR TREATMENT OF VOIDING DYSFUNCTION IN THE PEDIATRIC POPULATION

PURPOSE

We sought to determine whether the alpha-adrenergic antagonist doxazosin could be used as primary therapy in children with voiding dysfunction.

MATERIALS AND METHODS

Children were assigned to maintain a voiding diary and then randomly divided into a double-blind placebo controlled protocol (0.5 mg doxazosin or placebo). Duplicate uroflow studies with post-void residual evaluations and assessment of dysfunctional voiding scores were performed on initiation and completion of the study. At the conclusion parents were asked to rank the perceived improvement of the urinary incontinence (ie parental subjective perception of improvement).

RESULTS

No significant differences between doxazosin (18) and placebo (20) treated patients were found in the number of incontinent days per week, severity of incontinent episodes or alterations in uroflow patterns. Although not significant, 2 findings suggested a beneficial effect of doxazosin over placebo. Specifically, doxazosin decreased the number of incontinent episodes weekly from a median of 18 to 4, while the number of incontinent episodes weekly in the placebo group remained essentially unchanged, decreasing from 15 to 14 (p = 0.13). Doxazosin also improved the dysfunctional voiding scores over placebo, for an improvement of -3 vs 0 points. Further substantiating a doxazosin effect over placebo was the subjective perception of the parents that doxazosin significantly improved urinary continence (p <0.02).

CONCLUSIONS

Compared to placebo, doxazosin did not demonstrate a significant objective benefit, but produced a significant subjective benefit in the treatment of urinary incontinence secondary to voiding dysfunction.

The influence of individual, social group and household factors on the distribution of Ascaris lumbricoides within a community and implications for control strategies

The distribution of Ascaris lumbricoides within a community was examined at an initial mass anthelmintic treatment programme (January 1984) and following an 11-month period of reinfection (November 1984). Similar patterns of the negative binomial parameter kappa (an inverse measure of parasite aggregation) and the proportion of parasites within the most heavily infected quartile of the community were recorded at the two dates. The pattern of parasite aggregation within individuals, measured by parameter k, appears to be a stable characteristic of this host-parasite relationship. Significant variation in the intensity of infection was observed between households in the community. The number of family members living in the house strongly influenced the mean Ascaris burden and proportion of relatively heavy infections within adults and children. This finding suggests that the density of people in a house positively influences the frequency of exposure to infective stages of Ascaris, which in turn plays a major role in determining which individuals will harbour heavy infections. Positive correlations were recorded between the initial and reinfection burdens of individuals, relative to others in the community. The correlations were strongest in the youngest and oldest age groups and were more frequently significant among age-stratified groups of females, compared to males. A comparative examination of hypothetical treatment strategies suggests that for Ascaris infections in this community, targetting age groups with anthelmintic treatment would probably be more cost-effective in the long term in reducing the abundance of this parasite than selective treatment of individually identified heavy infections.

Contexts and patterns of men's commercial sexual partnerships in northeastern Thailand: implications for AIDS prevention

Results of an exploratory research project elaborating the contexts, patterns and specific scenarios of the commercial sexual activity of northeastern Thai men are reported. Data were collected using face-to-face surveys, focus groups, key informant interviews and observations in 32 northeastern villages (n = 744 men), 18 migrant labour camps housing sugarcane workers (n = 219 men), and five cattlemarkets in northeast Thailand. Fifty percent of married men and 43% of single men had visited female sex workers (FSW). Female sex worker visits occurred primarily prior to marriage, though 13% of married men had purchased sexual services within the past year. Nonmarital sexual activity was set within the socio-cultural frameworks of poverty, circular migration, a large commercial sex sector, and a belief system about men's sexuality and men's and women's gender roles. Sexual services were typically purchased as part of friendship group partying (paiy tiaow) and generally included heavy alcohol consumption. The most common scenario for visiting FSWs involved brothels, though cattlemarkets, festivals, and migrant labour situations were also scenarios for FSW contact. These each had unique characteristics that affected the likelihood that condoms would be used. The further the specifics of a scenario (as evaluated by men) diverged from those of brothel contact with an FSW, the less likely men were to identify this as having the potential for HIV transmission and the less likely they were to use a condom. AIDS prevention campaigns must be developed that are sensitive to the socio-cultural framework, contexts and specific scenarios within which nonmarital sexual contacts occur.

Opisthorchis viverrini and cholangiocarcinoma in Northeast Thailand

Population-based research is beginning to show clearly the devastating impact that Opisthorchis viverrini infection has on the Laos-descendent population of Northeast Thailand who love to eat uncooked meat and fish, one of which being the parasite's intermediate host: cyprinoid fish. Here, Melissa Haswell-Elkins, Paiboon Sithithaworn and David Elkins discuss the parasite's life cycle and epidemiology, highlighting the close relationship between this infection and bile duct carcinoma, which is a major cause of death among adults in rural Northeast Thailand.

Utility of duplex surveillance following iliac artery angioplasty and primary stenting

PURPOSE

To evaluate the clinical outcome and patency rates after iliac artery angioplasty and primary stenting using a noninvasive surveillance protocol that includes duplex ultrasonography.

METHODS

Sixty-seven patients (64 men; mean age 61 +/- 9 years, range 45-83) underwent stenting of 84 iliac systems for claudication (63%), rest pain (9%), tissue loss (20%), or failing lower limb bypass graft (8%). The surveillance algorithm included aortoiliac duplex scanning within 1 month and serial limb pressure measurements and femoral artery waveform analyses during follow-up. Iliac systems with a peak systolic velocity >300 cm/s and velocity ratio >2.0 by duplex and/or symptomatic or hemodynamic deterioration were considered failing and an indication for angiography.

RESULTS

During intermediate-term follow-up ranging to 36 months (mean 12), life table primary, assisted primary, and secondary patency rates for the treated iliac systems were 78%, 90%, and 98%, respectively, at 18 months. Assisted primary iliac system patency at 18 months was significantly worse in the 20 (24%) limbs having an outflow bypass done with or prior to iliac stenting (83% versus 100% without bypass, p = 0.01). Indirect clinical indicators found 17 (20%) suspected failing iliac systems, in which duplex imaging correctly identified 5 of 6 recurrent iliac stenoses and facilitated secondary endovascular intervention. Three (4%) stent occlusions occurred in the treated iliac systems despite surveillance.

CONCLUSIONS

Duplex surveillance after iliac stenting localizes failing inflow segments, optimizes assisted patency of the treated iliac system, and possesses greatest utility in patients with multilevel occlusive disease and outflow reconstructions.

Lung lamellar body amphiphilic topography: a morphological evaluation using the continuum theory of liquid crystals: I. Closed surfaces: closed spheres, concentric tori, and Dupin cyclides

The structure and symmetry of the bilayers of in vivo phospholipid lung lamellar bodies is shown to be analogous to thermotropic smectic-A liquid crystals and in vitro lyotropic multilamellar liquid crystalline liposomes. This structural similarity has led us to extend biophysical and geometrical principles that have long been used to predict the layer conformation in these in vitro systems to in vivo lung lamellar bodies. These configurations were demonstrated by electron micrographs of thin sections of rodent, monkey, and human lung lamellar bodies prepared by lipid-retaining embedment procedures. The bilayer configurations in all species were consistent with the two geometries predicted by minimal energy solutions of a continuum theory of liquid crystals subject to the boundary conditions imposed by the amphiphilic nature of lung surfactant lipid: concentric (either closed or partially closed) spheres and Dupin cyclides. These bilayer arrangements in lung lamellar bodies were virtually identical to the bilayer configuration of in vitro multilamellar liposomes. The agreement between the two predicted configurations and our observations shows that multilamellar liquid crystalline bilayer aggregate organization is universal in any aqueous environment.

Effect of predischarge interventions on aftercare attendance: process and outcome

A widely recognized problem in the mental health services delivery system is that of patients' early discontinuance of therapy. But less attention has been given to the high rate of nonattendance at initial appointments in outpatient mental health settings. The purpose of the study discussed in this article was to determine if particular predischarge interventions had an effect on whether psychiatric patients attended their initial aftercare appointments at a Veterans Administration mental health clinic. Two groups of patients were given predischarge interventions and one was not (a control group). Results showed a trend of greater attendance at initial aftercare appointments by those who received a predischarge intervention; however, the differences were not statistically significant. Suggestions for clinicians and researchers are provided.

Evaluation of HIV/AIDS education initiatives among women in northeastern Thai villages

A longitudinal, naturalistic experimental design was used in an evaluation of the effects of an HIV/AIDS educational pamphlet controlling for secular trends (most specifically media coverage of HIV/AIDS) in Northeastern Thailand. Nine hundred and fifty-four women from 18 villages completed KAP interviews either in the autumn of 1991 or 1992 with HIV/AIDS education pamphlets distributed to every household in 12 of these villages in the spring of 1992. Pamphlets influenced women's perceptions of personal risk from casual sources and the degree to which they volunteered that condoms were a means of prevention of HIV transmission. Both results were related to the content and style of presentation of information about sources of risk and about condoms in the pamphlets. Secular trends and an increase in communication between villagers had a significant influence on knowledge, perceived efficacy of self protection, readiness to use condoms, and perception of levels and sources of personal risk.

A research-based HIV intervention in northeast Thailand

This paper presents a case study of the development, implementation and evaluation of an HIV prevention strategy for rural, married women in the northeastern, Isan region of Thailand. The strategy is based on established principles of behaviour change, social learning, and community health promotion; grounded in baseline research, that identifies relevant contextual factors; community-based; evaluated; and applicable elsewhere. The methodology of the project includes four phases: data collection, strategy design, implementation, and evaluation. Baseline data were collected from an age-stratified sample of married women from 24 randomly chosen villages in Khon Kaen province in two waves. A total of 654 women participated in structured face-to-face interviews and 150 also participated in focus groups. Using the baseline data, a health promotion strategy including three components was designed: meetings with and training of village leaders and health workers; a five-part week long audio-drama, together with posters and other publicity conducted in villages; and village meetings to discuss the potential impact of HIV/AIDS on the village and to establish a village strategy to address this. This paper reports the results of the baseline data collection, how the data were used to produce an HIV prevention initiative for rural villages, results of the process evaluation and future development in HIV/AIDS prevention initiatives in this region.

Toward reducing the spread of HIV in northeastern Thai villages: evaluation of a village-based intervention

This paper presents results of the evaluation of an intervention designed for northeastern Thai villages and particularly for village women. The intervention was based on established principles of behavior change, social learning theory, and community health promotion, and it was grounded in elicitation research. A total of 600 women and 479 men and 12 villages participated in the evaluation which used data collected from face-to-face knowledge, attitude, practices (KAP) surveys, focus groups, and village meetings in a quasi-experimental pre- and post-control group design. Eight of the nine outcome goals set for the intervention were achieved with significant increases in married women taking the initiative in reducing the risk posed to them by the sexual activities of their husbands.

Supervisors' perceptions of the relationship between therapist self-disclosure and clinical effectiveness

The findings suggest that the clinical supervisors surveyed associate therapist effectiveness (i.e., competence and sophistication) with capacity for self-revelation in the presence of clients. Trainee maturity as therapist was not correlated highly with self-disclosure, a finding that may indicate that self-disclosure is (a) more independent of the training process than competence and sophistication, and (b) that self-disclosure, as manifested in the clinical context, may be more of a trait than a state-like personality characteristic.