Global overview of HIV/AIDS--a challenge for nurses

The human immunodeficiency virus (HIV) continues to spread around the world, insinuating itself into communities previously little troubled by the epidemic and strengthening its grip on areas where AIDS is already the leading cause of death in adults. (See global estimates on page 176.) Below, the evolving picture region by region.

Beyond the dichotomy: linking HIV prevention with care

In the past decade, the global strategy against AIDS has focused primarily upon prevention. Regardless of the effectiveness of prevention efforts being made today and advances in treatments, the numbers of persons infected globally continues to grow at an alarming rate, especially in developing countries. With numbers of infections increasing, and the trend to more people learning their HIV status earlier, demands for care will mount dramatically into the next century. This paper examines the virtually unexplored role care can play in prevention and its potential to have a mitigating effect on the pandemic. Critical issues addressed include (i) the relationship between care, HIV and productivity; (ii) the role of both care and prevention in promoting acceptance of HIV/AIDS as a community problem; (iii) the role of care in decreasing the vulnerability to HIV in specific populations such as women and children; (iv) the role of care in sustaining behavior change over time for infected persons; and (v) the synergy between improved treatments and prevention. Future areas of research are proposed examining these prevention and care issues that move beyond the traditional dichotomy.

Induction of immunity to Schistosoma mansoni: interaction of schistosomula with accessory leucocytes in murine skin and draining lymph nodes

A single exposure to radiation-attenuated cercariae of Schistosoma mansoni induces a high level of protective immunity in C57BL/6 mice, which is mediated by Th1 responses. Events in the skin and/or draining lymph nodes early after exposure are crucial for the induction of protection, and we have investigated the interactions of vaccinating parasites with host leucocytes in these 2 locations. We observed extensive lateral spreading of cercarial secretions along layers of the stratum corneum but not between keratinocytes. There was little direct contact with host leucocytes during the first 1-2 days when the parasites lay at the base of the epidermis, but cells accumulated in the underlying dermis. In contrast to normal parasites, attenuated larvae persisted in the dermis for > 10 days, often surrounded by aggregates of macrophages/dendritic cells. Whilst cells bearing MHC II, CD11b or CD11c markers were present in the lymph nodes, particularly in the periphery and paracortical areas, no obvious redistribution was seen as a result of parasite residence there for 5-15 days. However, ultrastructural observations revealed numerous cells with macrophage/dendritic morphology in the vicinity of parasites, in some instances closely adherent to the tegument. The observations strongly suggest that the tegument is a potent source of the antigens which prime the immune system in the lymph nodes of vaccinated mice for a protective response.

Effect of amlodipine on mode of death among patients with advanced heart failure in the PRAISE trial. Prospective Randomized Amlodipine Survival Evaluation

Investigations of calcium antagonists in patients with advanced heart failure have raised concern over an increased risk of worsening heart failure and heart failure deaths. We assessed the effect of amlodipine on cause-specific mortality in such patients enrolled in a randomized, double-blind, placebo-controlled trial. In total, 1,153 patients in New York Heart Association class IIIb or IV heart failure were randomized to receive amlodipine or placebo, along with angiotensin-converting enzyme inhibitors, diuretics, and digitalis. Over a median 14.5 months of follow-up, 413 patients died. Cardiovascular deaths accounted for 89% of fatalities, 50% of which were sudden deaths and 45% of which were due to pump failure, with fewer attributed to myocardial infarction (3.3%) or other cardiovascular causes (1.6%). Amlodipine treatment resulted in a greater relative reduction in sudden deaths (21%) than in pump failure deaths (6.6%) overall. When patients were classified by etiology of heart failure (ischemic or nonischemic), cause-specific mortality did not differ significantly between treatment groups in the ischemic stratum. In the nonischemic stratum, however, sudden deaths and pump failure deaths were reduced by 38% and 45%, respectively, with amlodipine. Thus, when added to digitalis, diuretics, and angiotensin-converting enzyme inhibitors in patients with advanced heart failure, amlodipine appears to have no effect on cause-specific mortality in ischemic cardiomyopathy, but both pump failure and sudden deaths appear to be decreased in nonischemic heart failure patients treated with amlodipine.

Distribution of D1S80 alleles in the Jordanian population

This study demonstrates that the locus D1S80 is highly polymorphic, with 24 different alleles and 66 genotypes in 215 Jordanians. This data set conforms to Hardy-Weinberg expectations(HWE).

Impaired development of Th2 cells in IL-13-deficient mice

We report that Th2 cell cultures generated using T cells or splenocytes from IL-13-deficient mice produce significantly reduced levels of IL-4, IL-5, and IL-10 compared with wild-type. In contrast, IL-4 and IL-5 production by mast cells stimulated in vitro with PMA, ionomycin, or IgE cross-linking are unaffected. In vitro Th2 cell differentiation cannot be rescued by the addition of exogenous factors, but in vivo antigen challenge and administration of IL-13 can increase Th2-like cytokine responses as can infection with the parasitic nematode Nippostrongylus brasiliensis. IL-13-deficient mice also have lower basal levels of serum IgE and biased antigen-specific immunoglobulin responses. Thus, IL-13 is an important regulator of Th2 commitment and may therefore play a central role in atopy and infectious diseases.

In the absence of IL-12, the induction of Th1-mediated protective immunity by the attenuated schistosome vaccine is impaired, revealing an alternative pathway with Th2-type characteristics

Vaccination of mice with irradiated Schistosoma mansoni larvae confers high levels of immunity which is mediated by Th1-type lymphocytes. To investigate a possible role for IL-12 in the induction of protection, we have compared the immune response of IL-12 p40-deficient (KO) mice and their C57BL/6 (WT) counterparts following vaccination. Cultured lymph node cells from KO mice had markedly altered cytokine profiles with significantly decreased production of IFN-gamma increased IL-4. Correspondingly, KO mice had enhanced levels of IgE. After challenge, cells recovered from the lungs of KO mice secreted abundant IL-4 and IL-5 but little IFN-gamma, while flow cytometric and histological analysis of lung cell populations recorded a very high proportion of eosinophils. The levels of protection in KO mice were substantially lower than in their WT counterparts, demonstrating the importance of IL-12 and Th1-mediated immune responses. This conclusion is reinforced by the administration of rIL-12 to KO mice immediately after vaccination which led to increased IFN-gamma and the restoration of protective immunity. Nevertheless, the data also indicated that the limited levels of protection induced in KO mice occur via an IL-12-independent pathway, possibly mediated by Th2 cells.

A comparison of two different systems for CD34+ selection of autologous or allogeneic PBSC collections

This study compared CD34 selection procedures using the CellPro CEPRATE and the Baxter Isolex 300 systems. Thirty-two procedures were performed, 19 CEPRATE and 13 Isolex. Median starting CD34 percentages were (CEPRATE/Isolex) 0.80% (range 0.24%-7.73%) and 0.85% (range 0.27%-10.17%), respectively (p = 0.788). After selection, there was a highly significant difference in purity of the product (CEPRATE/Isolex), 54% and 82% respectively (p < 0.0001). There was no significant difference in median recovery (CEPRATE/Isolex), 43% and 50%, respectively (p = 0.383). The starting CD34 percentage influenced the purity of the final product, and at high and low starting percentages, the Isolex produced superior purity. Improved efficacy of T cell depletion was observed with the Isolex, a median log depletion of 3.4 compared with 2.9 for the CEPRATE system (p = 0.012). In conclusion, the Isolex 300i produced a significantly higher purity CD34+ fraction, even at starting CD34+ levels of <0.5%, with no significant difference in recovery when compared with the CEPRATE system. The associated log T cell depletion is significantly improved with the Isolex system, with possible implications for use in CD34-selected allogeneic transplants.

Crystal structure of 2,5-diketo-D-gluconic acid reductase A complexed with NADPH at 2.1-A resolution

The three-dimensional structure of Corynebacterium 2, 5-diketo-D-gluconic acid reductase A (2,5-DKGR A; EC 1.1.1.-), in complex with cofactor NADPH, has been solved by using x-ray crystallographic data to 2.1-A resolution. This enzyme catalyzes stereospecific reduction of 2,5-diketo-D-gluconate (2,5-DKG) to 2-keto-L-gulonate. Thus the three-dimensional structure has now been solved for a prokaryotic example of the aldo-keto reductase superfamily. The details of the binding of the NADPH cofactor help to explain why 2,5-DKGR exhibits lower binding affinity for cofactor than the related human aldose reductase does. Furthermore, changes in the local loop structure near the cofactor suggest that 2,5-DKGR will not exhibit the biphasic cofactor binding characteristics observed in aldose reductase. Although the crystal structure does not include substrate, the two ordered water molecules present within the substrate-binding pocket are postulated to provide positional landmarks for the substrate 5-keto and 4-hydroxyl groups. The structural basis for several previously described active-site mutants of 2,5-DKGR A is also proposed. Recent research efforts have described a novel approach to the synthesis of L-ascorbate (vitamin C) by using a genetically engineered microorganism that is capable of synthesizing 2,5-DKG from glucose and subsequently is transformed with the gene for 2,5-DKGR. These modifications create a microorganism capable of direct production of 2-keto-L-gulonate from D-glucose, and the gulonate can subsequently be converted into vitamin C. In economic terms, vitamin C is the single most important specialty chemical manufactured in the world. Understanding the structural determinants of specificity, catalysis, and stability for 2,5-DKGR A is of substantial commercial interest.

Randomized multicentre trial of filgrastim as an adjunct to combination chemotherapy for Hodgkin's disease. West of Scotland Lymphoma Group

This study was intended to ascertain whether the adjunctive administration of filgrastim (r metHuG-CSF, Amgen) would influence the dose intensity of chemotherapy or the morbidity of myelosuppression in patients receiving MOPP or MOPP/EVAP hybrid chemotherapy for Hodgkin's disease. In a prospective randomized trial, two regimens for the treatment of Hodgkin's disease were compared. The substudy described here randomized patients receiving either regimen to receive filgrastim on the days when chemotherapy was not administered. During chemotherapy, parameters of myelosuppression were documented, including dose delays, the severity and duration of neutrophil and platelet nadirs, infective episodes, and resulting hospital admissions. In the MOPP arm, 13/25 eligible patients, and, in the MOPP/EVAP arm, 12/22 eligible patients, received filgrastim. The use of filgrastim made no statistically significant difference to the administered dose intensity for either MOPP (P = 0.57, 95% confidence interval (CI) 15-point increase to 8-point reduction) or MOPP/EVAP (P = 0.53; 95% CI 7-point increase to 11-point reduction). In patients receiving MOPP, filgrastim reduced the median duration of leucopenia (P = 0.007) and the severity of the white blood cell nadir (P = 0.036); however, no statistically significant effect (at the 5% level) was seen in platelet or haemoglobin nadirs, the number of days of in-patient hospitalization, the number of admissions for infective complications, the incidence, grade or duration of infections, or the incidence of febrile neutropenia. In patients receiving MOPP/EVAP, filgrastim had no significant effect on the duration or depth of leucopenia but was associated with a reduction in the median haemoglobin (P = 0.002) and platelet nadirs (P = 0.015). No effect on the above listed sequelae of myelosuppression was influenced by the administration of filgrastim. This study, although small, suggests that the routine use of filgrastim, aimed at influencing the administered dose intensity of conventional dose chemotherapy in Hodgkin's disease, is not warranted.

Should we adjust for covariates in nonlinear regression analyses of randomized trials?

The analyses of the primary objectives of randomized clinical trials often are not adjusted for covariates, except possibly for stratification variables. For analyses with linear models, adjustment is a precision issue only. We review the literature regarding logistic and Cox (proportional hazards) regression models. For these nonlinear analyses, omitting covariates from the analysis of randomized trials leads to a loss of efficiency as well as a change in the treatment effect being estimated. We recommend that the primary analyses adjust for important prognostic covariates in order to come as close as possible to the clinically most relevant subject-specific measure of treatment effect. Additional benefits would be an increase in efficiency of tests for no treatment effect and improved external validity. The latter is particularly relevant to meta-analyses.

Juvenile rheumatoid arthritis in a Canadian First Nations (aboriginal) population: onset subtypes and HLA associations

OBJECTIVE

To determine onset subtypes and HLA associations of juvenile rheumatoid arthritis (JRA) in a First Nations (aboriginal) population; to determine whether population frequencies of HLA antigens may explain the distribution of subtypes of JRA in this population.

METHODS

All patients were children from Manitoba and Northwestern Ontario seen in a single pediatric rheumatology clinic between 1975 and 1996. Patients were identified from a clinic registry. Controls were adults of Algonkian Cree and Ojibway heritage. Class I and II major histocompatibility (HLA) typing was performed for First Nations patients and controls.

RESULTS

There were a total of 74 First Nations patients with JRA. The relative frequency of rheumatoid factor (RF) positive polyarticular JRA was higher and that of pauciarticular JRA was lower in First Nations compared with Caucasian patients (42 versus 3% and 22 versus 58%, respectively; p = 0.00000). HLA-DRB1*04 (63%), 08 (43%), and 1402 (25%) were the most common DRB1 antigens among controls. The main subtypes of DRB1*04 were 0404 (33% of controls) and 0407 (23%). HLA typing was performed for 39 First Nations patients; 27 were Cree or Ojibway, 4 were from other tribes, and 8 were part First Nations. Among Cree and Ojibway, 59% of controls and 63% of patients with RF positive polyarticular JRA (n = 16) had HLA-DRB1 antigens bearing the rheumatoid arthritis (RA) shared epitope (OR 1.16, 95% CI: 0.38, 3.48). The OR for polyarticular RF positive JRA in those with DRB1*0802 and 0901 were 0.15, 95% CI: 0.02; and 1.24 and 5.83, 95% CI: 1.58, 28.38, respectively.

CONCLUSION

There was a high frequency of the RA shared epitope represented by both HLA-DRB1*0404 and 1402 in this Algonkian population. This high frequency may explain the high frequency of RF positive polyarticular JRA. DRB1*0802 may be protective, whereas DRB1*0901 may increase the risk for this subtype of JRA.

Nitrofurantoin prophylaxis for bacteriuria and urinary tract infection in children with neurogenic bladder on intermittent catheterization

OBJECTIVE

To determine the effect of nitrofurantoin prophylaxis on rates of bacteriuria and symptomatic urinary tract infection in children with chronic neurogenic bladder receiving clean intermittent catheterization.

DESIGN

Double-blind, placebo-controlled, crossover trial of 15 children receiving nitrofurantoin or placebo for 11 months (5 months receiving one drug, then 1 month of washout followed by 5 months of the alternate drug). Weekly home visits were made. During each visit a sample of bladder urine was obtained by intermittent catheterization, signs and symptoms of urinary tract infection were recorded, and all medications were recorded as well as a capsule count of the study drug.

RESULTS

During nitrofurantoin the frequency of bacteriuria remained high. Cultures of 74% (203 of 274) of the 274 samples on placebo were positive for a pathogen (> or = 10(4) colony-forming units per milliliter) compared with 65% (165 of 252) of the 252 samples on nitrofurantoin. The bacterial species responsible for bacteriuria, however, were altered; Escherichia coli, the most common pathogen isolated during placebo, was replaced by resistant Klebsiella spp. and Pseudomonas spp. during nitrofurantoin. The carriage of these resistant organisms tripled during nitrofurantoin. Symptomatic infection dropped in half on nitrofurantoin, but this decline was due solely to infections caused by E. coli. Despite an increased frequency of resistant organisms on nitrofurantoin prophylaxis, an increase in urinary tract infections caused by these resistant organisms did not occur.

CONCLUSION

Routine use of nitrofurantoin prophylaxis in an attempt to eradicate bacteriuria in patients with chronic neurogenic bladder is not effective.