Preventive and therapeutic strategies for respiratory syncytial virus infection

Respiratory syncytial virus (RSV) remains an important cause of pneumonitis in infants and in the elderly and immunosuppressed. Passive immunoprophylaxis of high-risk infants with the humanised monoclonal antibody palivizumab reduces RSV-related hospitalisation and admission to intensive care units by about 50%, although optimal and cost-effective use of this agent remains undefined. The development of an RSV vaccine is the focus of much research and recent advances with live attenuated vaccines are promising--several agents are in clinical trials. The value of the only therapeutic agent available to treat established infection, the antiviral ribavirin, is now seriously doubted and the agent is little used. New RSV chemotherapeutics are just entering clinical trials.

An examination of signs of disease progression in survivors of the Sydney Blood Bank Cohort (SBBC)

BACKGROUND

The Sydney Blood Bank Cohort (SBBC) was infected between 1981 and 1984 with a nef/LTR defective strain of HIV-1. Different responses to HIV-1 infection have emerged between cohort members in the last 5 years. Three recipients (C135, C64 and C49) remain asymptomatic, have normal CD4 T cell counts, below detection (BD) viral loads (VL), remain therapy naive and are termed long-term non-progressors (LTNP). The donor (D36) and the two recipients (C98 and C54) have significantly declining CD4 T cell counts, detectable VL and are now long-term survivors (LTS). In contrast, in the SA cohort, comparison study group for the SBBC, five of 24 remain therapy naïve after 15 years infection with HIV-1 and all have detectable VL.

OBJECTIVES

This paper examines different outcomes to long-term infection with HIV-1 in the SBBC and provides a brief overview of the therapy naïve in a comparison study group, the SA cohort.

STUDY DESIGN

Retrospective epidemiological follow-up of the SBBC and the SA cohort has been conducted for >15 years. Analysis of CD4 T cell counts, VL and intermittent monitoring of HIV-specific proliferative responses are reviewed. Viral sequence changes in the SBBC will be considered.

RESULTS

Prior to therapy D36 had a CD4 T cell count of 160/mm(3) and plasma VL of 9900 copies/ml while C98 had a CD4 T cell count of 387/mm(3) and plasma VL of 11491 copies/ml. After 1 month of therapy, plasma VL was BD (<400 copies/ml) and both showed significant increase in CD4 T cell counts. Molecular changes have occurred in D36 and C98 viral strains, the most recently evolved quasispecies have larger deletions in the nef/LTR region.

CONCLUSIONS

Infection with nef/LTR deleted HIV-1 has resulted in slower disease progression for the SBBC. The three LTNP have maintained normal low levels of activated CD8 T cells and strong HIV-specific proliferative responses to HIV-1 p24, which are associated with control of viral replication.

Specific inhibition of human immunodeficiency virus type 1 (HIV-1) integration in cell culture: putative inhibitors of HIV-1 integrase

To study the effect of potential human immunodeficiency virus type 1 (HIV-1) integrase inhibitors during virus replication in cell culture, we used a modified nested Alu-PCR assay to quantify integrated HIV DNA in combination with the quantitative analysis of extrachromosomal HIV DNA. The two diketo acid integrase inhibitors (L-708,906 and L-731,988) blocked the accumulation of integrated HIV-1 DNA in T cells following infection but did not alter levels of newly synthesized extrachromosomal HIV DNA. In contrast, we demonstrated that L17 (a member of the bisaroyl hydrazine family of integrase inhibitors) and AR177 (an oligonucleotide inhibitor) blocked the HIV replication cycle at, or prior to, reverse transcription, although both drugs inhibited integrase activity in cell-free assays. Quercetin dihydrate (a flavone) was shown to not have any antiviral activity in our system despite reported anti-integration properties in cell-free assays. This refined Alu-PCR assay for HIV provirus is a useful tool for screening anti-integration compounds identified in biochemical assays for their ability to inhibit the accumulation of integrated HIV DNA in cell culture, and it may be useful for studying the effects of these inhibitors in clinical trials.

Comparison of genotyping and phenotyping methods for determining susceptibility of HIV-1 to antiretroviral drugs

OBJECTIVE(S)

To compare antiretroviral resistance susceptibility testing of patient HIV-1 strains using genotype and phenotype methods.

DESIGN

Eighteen plasma samples with viral load > 2000 HIV-1 RNA copies/ml were randomly selected for testing by both methods. Disease and treatment data were available for all patients.

METHODS

Samples were analysed genotypically using a kit assay (HIV-1 Genotyping Systems, Applied Biosystems), performed by the Clinical Research Laboratory at Macfarlane Burnet Centre for Medical Research. Samples were analysed phenotypically using a rapid phenotypic assay (PhenoSenseTM HIV, ViroLogic), performed by the manufacturer. Results from both methods were interpreted using a defined protocol. Each susceptibility assay was performed and interpreted by individuals unaware of either the clinical data or the results of the other susceptibility assay. Concordance was defined categorically as either the presence of reduced susceptibility (> 2.5-fold change) in the phenotypic assay and resistance associated mutations in the genotypic assay, or the absence of these findings in both assays.

RESULTS

Concordance between phenotypic and genotypic susceptibility testing was 81% for nucleoside reverse transcriptase inhibitors, 91% for non-nucleoside reverse transcriptase inhibitors and 90% for protease inhibitors. Complete concordance between phenotype and genotype for all 14 drugs evaluated was observed in three (17%) patient samples.

CONCLUSIONS

Phenotypic and genotypic susceptibility appear to provide similar results. However, interpretation of genotypic results can be complicated, and both methods still require clinical validation.

Horner's syndrome after carotid endarterectomy--a case report

Horner's syndrome is described in a patient with anisocoria and unilateral lid ptosis 48 hours after an ipsilateral carotid endarterectomy. This case illustrates a rare iatrogenic complication of sympathetic nerve dysfunction following elective surgery.

nef-deleted HIV-1 inhibits phagocytosis by monocyte-derived macrophages in vitro but not by peripheral blood monocytes in vivo

OBJECTIVE

HIV-1 infection impairs a number of macrophage effector functions, but the mechanism is unknown. We studied the role of HIV-1 Nef in modulating phagocytosis by human monocytes and monocyte-derived macrophages (MDM).

DESIGN AND METHODS

Using a flow cytometric assay, phagocytosis of Mycobacterium avium complex (MAC) by monocytes in whole blood of Sydney Blood Bank Cohort (SBBC) members infected with a nef-deleted (Delta nef) strain of HIV-1 was compared with that of monocytes from uninfected or wild-type (WT) HIV-infected subjects. The specific impact of Nef on phagocytosis by MDM was determined by either infecting cells in vitro with Delta nef strains of HIV-1 or electroporating Nef into uninfected MDM.

RESULTS

MAC phagocytic capacity of monocytes from SBBC members was equivalent to that of cells from uninfected individuals (P = 0.81); it was greater than that of cells from individuals infected with WT HIV-1 (P < 0.0001), irrespective of CD4 counts and HIV viral load. In contrast, in vitro infection of MDM with either Delta nef or WT strains of HIV-1 resulted in similar levels of HIV replication and equivalent impairment of phagocytosis via Fc gamma and complement receptors. Electroporation of Nef into MDM did not alter phagocytic capacity.

CONCLUSIONS

This study provides evidence demonstrating the complex indirect effect of Nef on phagocytosis by peripheral blood monocytes (infrequently infected with HIV-1) in vivo. Conversely, the fact that MDM infected with either Delta nef or WT HIV-1 in vitro (high multiplicity of infection) show comparably impaired phagocytosis, indicates that HIV-1 infection of macrophages can directly impair function, independent of Nef.

Mass spectrometric analysis of cyanogen bromide fragments of integral membrane proteins at the picomole level: application to rhodopsin

Advances in time-of-flight mass spectrometry allow unit mass resolution of proteins and peptides up to about 6000 Da molecular weight. Identification of larger proteins and study of their posttranslational or experimental modifications by mass analysis is greatly enhanced by cleavage into smaller fragments. Most membrane proteins are difficult to mass analyze because of their high hydrophobicity, typical expression in low quantities, and because the detergents commonly used for solubilization may be deleterious to mass analysis. Cleavage with cyanogen bromide is beneficial for analysis of membrane proteins since the methionine cleavage sites are typically located in hydrophobic domains and cleavage at these points reduces the size of the hydrophobic fragments. Cyanogen bromide also gives high cleavage yields and introduces only volatile contaminants. Even after cleavage membrane proteins often contain fragments that are difficult to chromatograph. Matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) is capable of analyzing complex mixtures without chromatography. We present a MALDI MS method that quickly and reliably identifies the cyanogen bromide fragments and posttranslational modifications of reduced and alkylated bovine rhodopsin from as little as 30 pmol of rhodopsin in detergent-solubilized retinal rod disk membranes, using 1-5 pmol of digest per sample. The amino acid sequences of some of the peptides in the digest were confirmed by post source decomposition MS analysis of the same samples. The method appears to be general and applicable to the analysis of membrane proteins and the protein composition of membrane preparations.

Serologic evidence of hantavirus infection in sigmodontine rodents in Mexico

Antibodies to hantaviruses in two species of sigmodontine rodents (Peromyscus maniculatus and Reithrodontomys sumichrasti) collected in central Mexico are reported. Peromyscus maniculatus, a common species throughout much of Mexico, is the reservoir of Sin Nombre virus (SNV), the etiologic agent of the great majority of cases of hantavirus pulmonary syndrome (HPS) in North America. Although the identity of the virus detected in P. maniculatus in Mexico could not be determined by these serologic results, our findings suggest that SNV may occur throughout the range of P. maniculatus in North America. If true, the failure to identify HPS in Mexico is not due to the absence of pathogenic hantaviruses in Mexico.

Clinical, manometric, and EMG characteristics of patients with fecal incontinence

Fecal incontinence occurs frequently in both men and women. Yet, few studies on fecal incontinence have separated the evaluation and interpretation of data by gender. This study was designed to identify differences in the clinical, anorectal manometry, and electromyography (EMG) characteristics between male and female patients with fecal incontinence. We compared 53 incontinent males (mean age, 64 years) with 72 incontinent females (mean age, 61 years). Each patient underwent computerized anorectal manometry, and invasive (pudendal nerve conduction studies and concentric needle EMG) and noninvasive EMG (anal sensor surface electrode). An anal incontinence score (AIS) ranging from 0 to 6 was used to categorize patients. Male patients had higher incontinence scores at presentation (AIS greater than 4, 70% vs. 54%). Female patients had significantly lower resting pressure (40 vs. 53 mmHg, p < 0.05) and more women had sphincter asymmetry (36% vs. 25%, p < 0.05). Both groups had similar PNTMLs (2.41 vs. 2.47 ms). Difference was seen in the net strength of the sphincter (women 4.0 microV vs. men 8.0 microV, p < 0.05), as measured by noninvasive EMG. In conclusion, it is well known that there are differences in anorectal physiologic function between male and female patients with normal continence. Comparing male and female patients with fecal incontinence suggests that female patients tend to have worse sphincter function that men. Both groups had similar EMG alterations, suggesting a common neurogenic injury as etiology. Future studies are needed to address the sexes separately.

The natural history of Hendra and Nipah viruses

Pteropid bats (flying foxes), species of which are the probable natural host of both Hendra and Nipah viruses, occur in overlapping populations from India to Australia. Ecological changes associated with land use and with animal husbandry practices appear most likely to be associated with the emergence of these two agents.

Live attenuated HIV vaccines: predicting the tradeoff between efficacy and safety

The utility of live attenuated vaccines for controlling HIV epidemics is being debated. Live attenuated HIV vaccines (LAHVs) could be extremely effective in protecting against infection with wild-type strains, but may not be completely safe as the attenuated strain could cause AIDS in some vaccinated individuals. We present a theoretical framework for evaluating the consequences of the tradeoff between vaccine efficacy (in terms of preventing new infections with wild-type strains) and safety (in terms of vaccine-induced AIDS deaths). We use our framework to predict, for Zimbabwe and Thailand, the epidemiological impact of 1,000 different (specified by efficacy and safety characteristics) LAHVs. We predict that paradoxically: (i) in Zimbabwe (where transmission is high) LAHVs would significantly decrease the AIDS death rate, but (ii) in Thailand (where transmission is low) exactly the same vaccines (in terms of efficacy and safety characteristics) would increase the AIDS death rate. Our results imply that a threshold transmission rate exists that determines whether any given LAHV has a beneficial or a detrimental impact. We also determine the vaccine perversity point, which is defined in terms of the fraction of vaccinated individuals who progress to AIDS as a result of the vaccine strain. Vaccination with any LAHV that causes more than 5% of vaccinated individuals to progress to AIDS in 25 years would, even 50 years later, lead to perversity (i.e., increase the annual AIDS death rate) in Thailand; these same vaccines would lead to decreases in the annual AIDS death rate in Zimbabwe.

Carboxyl-terminal fragments of Alzheimer beta-amyloid precursor protein accumulate in restricted and unpredicted intracellular compartments in presenilin 1-deficient cells

Absence of functional presenilin 1 (PS1) protein leads to loss of gamma-secretase cleavage of the amyloid precursor protein (betaAPP), resulting in a dramatic reduction in amyloid beta peptide (Abeta) production and accumulation of alpha- or beta-secretase-cleaved COOH-terminal fragments of betaAPP (alpha- or beta-CTFs). The major COOH-terminal fragment (CTF) in brain was identified as betaAPP-CTF-(11-98), which is consistent with the observation that cultured neurons generate primarily Abeta-(11-40). In PS1(-/-) murine neurons and fibroblasts expressing the loss-of-function PS1(D385A) mutant, CTFs accumulated in the endoplasmic reticulum, Golgi, and lysosomes, but not late endosomes. There were some subtle differences in the subcellular distribution of CTFs in PS1(-/-) neurons as compared with PS1(D385A) mutant fibroblasts. However, there was no obvious redistribution of full-length betaAPP or of markers of other organelles in either mutant. Blockade of endoplasmic reticulum-to-Golgi trafficking indicated that in PS1(-/-) neurons (as in normal cells) trafficking of betaAPP to the Golgi compartment is necessary before alpha- and beta-secretase cleavages occur. Thus, although we cannot exclude a specific role for PS1 in trafficking of CTFs, these data argue against a major role in general protein trafficking. These results are more compatible with a role for PS1 either as the actual gamma-secretase catalytic activity or in other functions indirectly related to gamma-secretase catalysis (e.g. an activator of gamma-secretase, a substrate adaptor for gamma-secretase, or delivery of gamma-secretase to betaAPP-containing compartments).

Nutritional status of patients in a long-stay hospital for people with mental handicap

OBJECTIVE

To investigate the general nutritional status of patients in Alexandra Hospital, Cape Town, and to determine whether dietary copper deficiency was causing anaemia in hospital patients.

DESIGN

Descriptive and cross-sectional analytical studies.

SETTING

A long-stay hospital for people with mental handicap.

SUBJECTS

Information was obtained from the total hospital population. In addition, groups of 15 patients were selected from each of two specific wards, one with active and the other inactive patients. To determine whether copper deficiency was causing anaemia, a sample of 30 patients, divided into three groups (a hypochromic microcytic, a normochromic anaemic and a non-anaemic group) was studied.

MAIN OUTCOME MEASURES

Body mass indices (BMI) and daily dietary intakes were compared with Recommended Daily Allowance (RDA) values. Serum copper and serum caeruloplasmin levels were used to detect possible copper deficiency.

RESULTS

A considerable number of patients were found to be underweight (32% of males and 26% of females had BMIs < 20). A smaller number were obese (6% of males and 17% of females had BMIs > 30). Poor nutrition was more common in severely handicapped patients and those with acquired causes of their mental handicap. Subjects with Down syndrome were generally well nourished and occasionally obese. Poor dietary intakes of biotin, pantothenic acid, vitamin D and copper were encountered. The serum copper and caeruloplasmin values were found to be within normal limits. Patients with hypochromic, microcytic anaemia had higher serum copper and caeruloplasmin levels than those with normochromic anaemia and the control group.

CONCLUSIONS

A number of nutritional problems among the inpatient population were found. Many were undernourished, while a smaller number of patients were overweight. In both the active and inactive wards macronutrient intakes were generally within normal limits. However, some micronutrient nutritional deficiencies were encountered. We were unable to establish that dietary copper deficiency was the cause of anaemia in our patients. Elevated serum copper and caeruloplasmin levels found in hypochromic, microcytic patients were thought to result from the existence of low-grade infection, associated with elevation of the acute-phase protein, caeruloplasmin.

An epidemic without illness. Using dna markers to model infection

PURPOSE: Combining molecular biology with infection control interventions can increase compliance and allow objective measurement of effectiveness. We developed a group of PCR detectable non-infectious DNA markers that can be used to model infection and provide immediate feedback on hygiene practices in institutional settings. In previous studies, we illustrated that the markers were spread in the environment in the same manner as infectious particles.METHODS: We are conducting a prospective study in 10 child care centers in order to 1) confirm that the DNA markers are valid surrogates for bacteria and viruses; 2) identify specific foci of contamination and modes of transmission; 3) illustrate the effectiveness of infection control programs utilizing the DNA markers. Centers are randomized to receive an interactive educational infection control intervention or a standard immunization intervention. The DNA markers are introduced into the center and the rate of dispersion of the DNA markers is compared with directly observed changes in hygiene behavior among the staff.RESULTS: Initial results indicate that the markers can be removed mechanically by hand washing and that common over-the-counter cleaners are effective in inactivating the markers. Toys, countertops and doorknobs appear to be more important as infectious reservoirs than brief casual contact. Data from the prospective study will be available prior to September, 2000.CONCLUSIONS: This novel approach utilizing an objective measurement will be used to identify the interaction between behavior and environmental reservoirs of infection and drive future strategies for infection control.

Interactions between poly(2-ethylacrylic acid) and lipid bilayer membranes: effects of cholesterol and grafted poly(ethylene glycol)

The exchange of the protonatable polymer, poly(2-ethylacrylic acid) (PEAA), has been studied with vesicle membranes containing cholesterol from 0 to 60 mol% or PEG2000-lipid (5 mol%). The release of an entrapped dye from 100 nm extruded liposomes was used as an assay for membrane perturbation by the polymer as a function of pH. The inclusion of cholesterol was found to reduce the pH at which the polymer caused release of the dye from the lipid vesicles, and the degree of polymer protonation (i.e., degree of hydrophobicity) correlated well with the increase in elastic expansion modulus of the vesicle bilayer. The results are discussed in terms of a balance between polymer solubility and membrane expansion. With respect to the PEG barrier, the presence of 5 mol% PEG2000, which represents full surface coverage, did not prevent PEAA from inducing contents release, demonstrating that highly hydrated polymeric layers are not effective barriers for other water soluble polymers, and may point to some association between the two polymers.

Ventral marsupialisation in the treatment of gastric dilatation-volvulus in two dogs

A ventral marsupialisation technique is described which was used successfully to manage gastric dilatation-volvulus (GDV) in two large breed dogs. The procedure allowed the stomach to be completely and rapidly emptied and lavaged without peritoneal contamination. Drainage was maintained in the postoperative period for both dogs and the technique was expected to result in a permanent ventral gastropexy.

The role of C-peptide in the classification of diabetes mellitus

We investigated twenty-one insulin-using patients, who had all been labelled as having insulin dependent diabetes mellitus (IDDM) or type 1 diabetes. Physicians have been erroneously using the term IDDM loosely to include all diabetics on insulin. The clinical criteria of the National Diabetes Data Group/WHO were used to reclassify these patients. Only thirteen were found to have IDDM and eight non-insulin dependent diabetes mellitus (NIDDM). Using fasting C-peptide values, only five of the thirteen with clinical IDDM truly had IDDM, the others might have maturity onset diabetes of the young (MODY) or diabetes in the young. Of the eight with clinical NIDDM seven had normal to high C-peptide values; the lone patient with low C-peptide values had diabetes diagnosed at age 64 years. We conclude that the clinical classification of diabetes mellitus may be inaccurate and that C-peptide evaluation improves the accuracy of the classification.