Detection and Management of Amyloid-Related Imaging Abnormalities in Patients with Alzheimer's Disease Treated with Anti-Amyloid Beta Therapy

Amyloid-related imaging abnormalities (ARIA) are adverse events reported in Alzheimer's disease trials of anti-amyloid beta (Aβ) therapies. This review summarizes the existing literature on ARIA, including bapineuzumab, gantenerumab, donanemab, lecanemab, and aducanumab studies, with regard to potential risk factors, detection, and management. The pathophysiology of ARIA is unclear, but it may be related to binding of antibodies to accumulated Aβ in both the cerebral parenchyma and vasculature, resulting in loss of vessel wall integrity and increased leakage into surrounding tissues. Radiographically, ARIA-E is identified as vasogenic edema in the brain parenchyma or sulcal effusions in the leptomeninges/sulci, while ARIA-H is hemosiderin deposits presenting as microhemorrhages or superficial siderosis. ARIA tends to be transient and asymptomatic in most cases, typically occurring early in the course of treatment, with the risk decreasing later in treatment. Limited data are available on continued dosing following radiographic findings of ARIA; hence, in the event of ARIA, treatment should be continued with caution and regular monitoring. Clinical trials have implemented management approaches such as temporary suspension of treatment until symptoms or radiographic signs of ARIA have resolved or permanent discontinuation of treatment. ARIA largely resolves without concomitant treatment, and there are no systematic data on potential treatments for ARIA. Given the availability of an anti-Aβ therapy, ARIA monitoring will now be implemented in routine clinical practice. The simple magnetic resonance imaging sequences used in clinical trials are likely sufficient for effective detection of cases. Increased awareness and education of ARIA among clinicians and radiologists is vital.

Evaluation of virucidal activity of residual quaternary ammonium-treated surfaces on SARS-CoV-2

BACKGROUND

The COVID-19 pandemic has had an unprecedented impact on global health and the world's economies. Proliferation of virulent and deadly SARS-CoV-2 variants require effective transmission mitigation strategies. Under reasonable environmental conditions, culturable and infectious SARS-CoV-2 can survive on contaminated fomites from hours to months. In the present study we evaluated a surface-anchored polymeric quaternary ammonium antimicrobial to help reduce fomite transmission of SARS-CoV-2 from contaminated surfaces.

METHODS

Two studies were performed on antimicrobial pre-treated metal disks in March 2020 by two independent Biosafety Level III (BSL-3) equipped laboratories in April 2020. These facilities were in Belgium (the Rega Medical Research Institute) and Australia (the Peter Doherty Institute) and independently applied quantitative carrier-based methodologies using the authentic SARS-CoV-2 isolates (hCoV-19/Australia/VIC01/2020, hCoV-19/Belgium/GHB-03021/2020).

RESULTS

Residual dry tests were independently conducted at both facilities and demonstrated sustained virion destruction (108.23 TCID50/carrier GHB-03021 isolate, and 103.66 TCID50/carrier VIC01 isolate) 1 hour (drying) + 10 minutes after inoculation. Reductions are further supported by degradation of RNA on antimicrobial-treated surfaces using qRT-PCR.

CONCLUSIONS

Using a polymeric quaternary ammonium antimicrobial (EPA/PMRA registered) the results independently support a sustained antiviral effect via SARS-CoV-2 virion destruction and viral RNA degradation. This indicates that silane-anchored quaternary ammonium compound (SiQAC-18) treated surfaces could play an important role in mitigating the communicability and fomite transmission of SARS-CoV-2.

Water-Borne Nanocoating for Rapid Inactivation of SARS-CoV-2 and Other Viruses

The rise in coronavirus variants has resulted in surges of the disease across the globe. The mutations in the spike protein on the surface of the virion membrane not only allow for greater transmission but also raise concerns about vaccine effectiveness. Preventing the spread of SARS-CoV-2, its variants, and other viruses from person to person via airborne or surface transmission requires effective inactivation of the virus. Here, we report a water-borne spray-on coating for the complete inactivation of viral particles and degradation of their RNA. Our nanoworms efficiently bind and, through subsequent large nanoscale conformational changes, rupture the viral membrane and subsequently bind and degrade its RNA. Our coating completely inactivated SARS-CoV-2 (VIC01) and an evolved SARS-CoV-2 variant of concern (B.1.1.7 (alpha)), influenza A, and a surrogate capsid pseudovirus expressing the influenza A virus attachment glycoprotein, hemagglutinin. The polygalactose functionality on the nanoworms targets the conserved S2 subunit on the SARS-CoV-2 virion surface spike glycoprotein for stronger binding, and the additional attachment of guanidine groups catalyze the degradation of its RNA genome. Coating surgical masks with our nanoworms resulted in complete inactivation of VIC01 and B.1.1.7, providing a powerful control measure for SARS-CoV-2 and its variants. Inactivation was further observed for the influenza A and an AAV-HA capsid pseudovirus, providing broad viral inactivation when using the nanoworm system. The technology described here represents an environmentally friendly coating with a proposed nanomechanical mechanism for inactivation of both enveloped and capsid viruses. The functional nanoworms can be easily modified to target viruses in future pandemics, and is compatible with large scale manufacturing processes.

Evaluation of 6 Commercial SARS-CoV-2 Serology Assays Detecting Different Antibodies for Clinical Testing and Serosurveillance

Background

Serological testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) complements nucleic acid tests for patient diagnosis and enables monitoring of population susceptibility to inform the coronavirus disease 2019 (COVID-19) pandemic response. It is important to understand the reliability of assays with different antigen or antibody targets to detect humoral immunity after SARS-CoV-2 infection and to understand how antibody (Ab) binding assays compare to those detecting neutralizing antibody (nAb), particularly as we move into the era of vaccines.

Methods

We evaluated the performance of 6 commercially available enzyme-linked immunosorbent assays (ELISAs), including a surrogate virus neutralization test (sVNT), for detection of SARS-CoV-2 immunoglobulins (IgA, IgM, IgG), total or nAb. A result subset was compared with a cell culture-based microneutralization (MN) assay. We tested sera from patients with prior reverse transcription polymerase chain reaction-confirmed SARS-CoV-2 infection, prepandemic sera, and potential cross-reactive sera from patients with other non-COVID-19 acute infections.

Results

For sera collected >14 days post-symptom onset, the assay achieving the highest sensitivity was the Wantai total Ab at 100% (95% CI, 94.6%-100%), followed by 93.1% for Euroimmun NCP-IgG, 93.1% for GenScript sVNT, 90.3% for Euroimmun S1-IgG, 88.9% for Euroimmun S1-IgA, and 83.3% for Wantai IgM. Specificity for the best-performing assay was 99.5% for the Wantai total Ab, and for the lowest-performing assay it was 97.1% for sVNT (as per the Instructions for Use [IFU]). The Wantai Total Ab had the best agreement with MN at 98% followed by Euroimmun S1-IgA, Euro NCP-IgG, and sVNT (as per IFU) with 97%, 97% and 95%, respectively; Wantai IgM had the poorest agreement at 93%.

Conclusions

Performance characteristics of the SARS-CoV-2 serology assays detecting different antibody types are consistent with those found in previously published reports. Evaluation of the surrogate virus neutralization test in comparison to the Ab binding assays and a cell culture-based neutralization assay showed good result correlation between all assays. However, correlation between the cell-based neutralization test and some assays detecting Ab's not specifically involved in neutralization was higher than with the sVNT. This study demonstrates the reliability of different assays to detect the humoral immune response following SARS-CoV-2 infection, which can be used to optimize serological test algorithms for assessing antibody responses post-SARS-CoV-2 infection or vaccination.

Optimal preparation of SARS-CoV-2 viral transport medium for culture

Introduction

The sudden arrival of the COVID-19 pandemic placed significant stresses on supply chains including viral transport medium (VTM). The VTM that was urgently required needed to support viral replication, as well as other routine diagnostic approaches. We describe the preparation and validation testing of VTM for rapidly expanding diagnostic testing, where the capacity of the VTM to preserve viral integrity, for culture, isolation and full sequence analysis, was maintained.

Methods

VTM was prepared using different methods of sterilization then ‘spiked’ with virus. The VTM was investigated using viral culture in Vero cells, and for nucleic acid detection by quantitative PCR.

Results

The best results were obtained by filter and autoclave-based sterilization. The VTM proved robust for culture-based analyses provided the inoculated VTM was stored at 4 °C, and tested within 48 h. The filtered VTM also supported PCR-based diagnosis for at least 5 days when the mock inoculated VTM was held at room temperature.

Discussion

The manual handling of VTM production, including filling and sterilization, was optimized. SARS-CoV-2 was spiked into VTM to assess different sterilization methods and measure the effects of storage time and temperature upon VTM performance. While most diagnostic protocols will not require replication competent virus, the use of high quality VTM will allow for the next phase of laboratory analysis in the COVID-19 pandemic, including drug and antibody susceptibility analysis of re-isolated SARS-CoV-2, and for the testing of vaccine escape mutants.

Evaluation of Serological Tests for SARS-CoV-2: Implications for Serology Testing in a Low-Prevalence Setting

BACKGROUND

Robust serological assays are essential for long-term control of the COVID-19 pandemic. Many recently released point-of-care (PoCT) serological assays have been distributed with little premarket validation.

METHODS

Performance characteristics for 5 PoCT lateral flow devices approved for use in Australia were compared to a commercial enzyme immunoassay (ELISA) and a recently described novel surrogate virus neutralization test (sVNT).

RESULTS

Sensitivities for PoCT ranged from 51.8% (95% confidence interval [CI], 43.1%-60.4%) to 67.9% (95% CI, 59.4%-75.6%), and specificities from 95.6% (95% CI, 89.2%-98.8%) to 100.0% (95% CI, 96.1%-100.0%). ELISA sensitivity for IgA or IgG detection was 67.9% (95% CI, 59.4%-75.6%), increasing to 93.8% (95% CI, 85.0%-98.3%) for samples >14 days post symptom onset. sVNT sensitivity was 60.9% (95% CI, 53.2%-68.4%), rising to 91.2% (95% CI, 81.8%-96.7%) for samples >14 days post symptom onset, with specificity 94.4% (95% CI, 89.2%-97.5%).

CONCLUSIONS

Performance characteristics for COVID-19 serological assays were generally lower than those reported by manufacturers. Timing of specimen collection relative to onset of illness or infection is crucial in reporting of performance characteristics for COVID-19 serological assays. The optimal algorithm for implementing serological testing for COVID-19 remains to be determined, particularly in low-prevalence settings.

Impact of Hepatitis B Virus Coinfection on Human T-Lymphotropic Virus Type 1 Clonality in an Indigenous Population of Central Australia

The prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and hepatitis B virus (HBV) coinfection is high in certain Indigenous Australian populations, but its impact on HTLV-1 has not been described. We compared 2 groups of Indigenous adults infected with HTLV-1, either alone or coinfected with HBV. The 2 groups had a similar HTLV-1 proviral load, but there was a significant increase in clonal expansion of HTLV-1-infected lymphocytes in coinfected asymptomatic individuals. The degree of clonal expansion was correlated with the titer of HBV surface antigen. We conclude that HTLV-1/HBV coinfection may predispose to HTLV-1-associated malignant disease.

Differentiating founder and chronic HIV envelope sequences

Significant progress has been made in characterizing broadly neutralizing antibodies against the HIV envelope glycoprotein Env, but an effective vaccine has proven elusive. Vaccine development would be facilitated if common features of early founder virus required for transmission could be identified. Here we employ a combination of bioinformatic and operations research methods to determine the most prevalent features that distinguish 78 subtype B and 55 subtype C founder Env sequences from an equal number of chronic sequences. There were a number of equivalent optimal networks (based on the fewest covarying amino acid (AA) pairs or a measure of maximal covariance) that separated founders from chronics: 13 pairs for subtype B and 75 for subtype C. Every subtype B optimal solution contained the founder pairs 178–346 Asn-Val, 232–236 Thr-Ser, 240–340 Lys-Lys, 279–315 Asp-Lys, 291–792 Ala-Ile, 322–347 Asp-Thr, 535–620 Leu-Asp, 742–837 Arg-Phe, and 750–836 Asp-Ile; the most common optimal pairs for subtype C were 644–781 Lys-Ala (74 of 75 networks), 133–287 Ala-Gln (73/75) and 307–337 Ile-Gln (73/75). No pair was present in all optimal subtype C solutions highlighting the difficulty in targeting transmission with a single vaccine strain. Relative to the size of its domain (0.35% of Env), the α₄β₇ binding site occurred most frequently among optimal pairs, especially for subtype C: 4.2% of optimal pairs (1.2% for subtype B). Early sequences from 5 subtype B pre-seroconverters each exhibited at least one clone containing an optimal feature 553–624 (Ser-Asn), 724–747 (Arg-Arg), or 46–293 (Arg-Glu).

Trimeric gp120-specific bovine monoclonal antibodies require cysteine and aromatic residues in CDRH3 for high affinity binding to HIV Env

We isolated HIV-1 Envelope (Env)-specific memory B cells from a cow that had developed high titer polyclonal immunoglobulin G (IgG) with broad neutralizing activity after a long duration vaccination with HIV-1_AD8 Env gp140 trimers. We cloned the bovine IgG matched heavy (H) and light (L) chain variable (V) genes from these memory B cells and constructed IgG monoclonal antibodies (mAbs) with either a human constant (C)-region/bovine V-region chimeric or fully bovine C and V regions. Among 42 selected Ig+ memory B cells, two mAbs (6A and 8C) showed high affinity binding to gp140 Env. Characterization of both the fully bovine and human chimeric isoforms of these two mAbs revealed them as highly type-specific and capable of binding only to soluble AD8 uncleaved gp140 trimers and covalently stabilized AD8 SOSIP gp140 cleaved trimers, but not monomeric gp120. Genomic sequence analysis of the V genes showed the third heavy complementarity-determining region (CDRH3) of 6A mAb was 21 amino acids in length while 8C CDRH3 was 14 amino acids long. The entire V heavy (VH) region was 27% and 25% diverged for 6A and 8C, respectively, from the best matched germline V genes available, and the CDRH3 regions of 6A and 8C were 47.62% and 78.57% somatically mutated, respectively, suggesting a high level of somatic hypermutation compared with CDRH3 of other species. Alanine mutagenesis of the VH genes of 6A and 8C, showed that CDRH3 cysteine and tryptophan amino acids were crucial for antigen binding. Therefore, these bovine vaccine-induced anti-HIV antibodies shared some of the notable structural features of elite human broadly neutralizing antibodies, such as CDRH3 size and somatic mutation during affinity-maturation. However, while the 6A and 8C mAbs inhibited soluble CD4 binding to gp140 Env, they did not recapitulate the neutralizing activity of the polyclonal antibodies against HIV infection.

Biology of mucosally transmitted sexual infection-translating the basic science into novel HIV intervention: a workshop summary

A group of over 200 international scientists came together on April 15 in Sydney, Australia just before the 2012 International Microbicides Conference as a part of a workshop to address the basic concepts and factors that modulate HIV infection at the mucosal surface. The meeting focused on defining the interaction between virus, prevailing host physiology, microbiota, and innate and adaptive immune responses and how they combine to impact the outcome at the moment of potential viral transmission. Speakers examined the biology of HIV entry during transmission, innate and natural antiviral mechanisms at the mucosa, microbicide efficacy, pharmacokinetic, and pharmacodynamics, animal models, and opportunities for combining HIV prevention strategies. Other viral infection models both in vivo and in vitro were considered for the insights they provided into HIV transmission events. The workshop raised important questions that we need to answer to further our basic understanding of host and viral factors influencing HIV transmission to inform the development of novel prevention strategies.

CD4+ T-cell deficiency in HIV patients responding to antiretroviral therapy is associated with increased expression of interferon-stimulated genes in CD4+ T cells

Most patients with human immunodeficiency virus (HIV) who remain CD4(+) T-cell deficient on antiretroviral therapy (ART) exhibit marked immune activation. As CD4(+) T-cell activation may be mediated by microbial translocation or interferon-alpha (IFN-α), we examined these factors in HIV patients with good or poor CD4(+) T-cell recovery on long-term ART. Messenger RNA levels for 3 interferon-stimulated genes were increased in CD4(+) T cells of patients with poor CD4(+) T-cell recovery, whereas levels in patients with good recovery did not differ from those in healthy controls. Poor CD4(+) T-cell recovery was also associated with CD4(+) T-cell expression of markers of activation, senescence, and apoptosis, and with increased serum levels of the lipopolysaccharide receptor and soluble CD14, but these were not significantly correlated with expression of the interferon-stimulated genes. Therefore, CD4(+) T-cell recovery may be adversely affected by the effects of IFN-α, which may be amenable to therapeutic intervention.

Expression and reactivation of HIV in a chemokine induced model of HIV latency in primary resting CD4+ T cells

Background

We recently described that HIV latent infection can be established in vitro following incubation of resting CD4+ T-cells with chemokines that bind to CCR7. The main aim of this study was to fully define the post-integration blocks to virus replication in this model of CCL19-induced HIV latency.

Results

High levels of integrated HIV DNA but low production of reverse transcriptase (RT) was found in CCL19-treated CD4+ T-cells infected with either wild type (WT) NL4.3 or single round envelope deleted NL4.3 pseudotyped virus (NL4.3- Δenv). Supernatants from CCL19-treated cells infected with either WT NL4.3 or NL4.3- Δenv did not induce luciferase expression in TZM-bl cells, and there was no expression of intracellular p24. Following infection of CCL19-treated CD4+ T-cells with NL4.3 with enhanced green fluorescent protein (EGFP) inserted into the nef open reading frame (NL4.3- Δnef-EGFP), there was no EGFP expression detected. These data are consistent with non-productive latent infection of CCL19-treated infected CD4+ T-cells. Treatment of cells with phytohemagluttinin (PHA)/IL-2 or CCL19, prior to infection with WT NL4.3, resulted in a mean fold change in unspliced (US) RNA at day 4 compared to day 0 of 21.2 and 1.1 respectively (p = 0.01; n = 5), and the mean expression of multiply spliced (MS) RNA was 56,000, and 5,000 copies/million cells respectively (p = 0.01; n = 5). In CCL19-treated infected CD4+ T-cells, MS-RNA was detected in the nucleus and not in the cytoplasm; in contrast to PHA/IL-2 activated infected cells where MS RNA was detected in both. Virus could be recovered from CCL19-treated infected CD4+ T-cells following mitogen stimulation (with PHA and phorbyl myristate acetate (PMA)) as well as TNFα, IL-7, prostratin and vorinostat.

Conclusions

In this model of CCL19-induced HIV latency, we demonstrate HIV integration without spontaneous production of infectious virus, detection of MS RNA in the nucleus only, and the induction of virus production with multiple activating stimuli. These data are consistent with ex vivo findings from latently infected CD4+ T-cells from patients on combination antiretroviral therapy, and therefore provide further support of this model as an excellent in vitro model of HIV latency.

Does RNA interference provide new hope for control of chronic hepatitis B infection?

Hepatitis B virus (HBV) infection is a global human health problem, with an estimated 350 million people having chronic hepatitis B (CHB) infection worldwide. The majority of infections acquired during adulthood are resolved without intervention; however, infections acquired at birth or during early childhood have a 90% chance of progressing to CHB, leading to a host of adverse effects on the liver, including cirrhosis and cancer. CHB is currently treated with a combination of cytokines and/or nucleoside/nucleotide analogues; however, adverse side effects to cytokine therapy and the selection of resistance mutations to nucleoside analogues often abrogate the efficacy of treatment. The recent discovery that small interfering RNA and microRNA are active in mammalian cells suggests it might be possible to supplement existing HBV therapies with small RNA-based therapeutic(s).

Identification and characterisation of the porcine 7SK RNA polymerase III promoter for short hairpin RNA expression

The RNA polymerase III (pol III) type III promoters U6 and 7SK are routinely used to express short hairpin RNA (shRNA) molecules from a DNA construct. In this study, we identified, characterised and compared the porcine 7SK promoter in porcine (homologous) and non-porcine (heterologous) derived cell lines. The porcine 7SK small nuclear RNA (snRNA) was identified by alignment with known sequences and further characterisation of the upstream regions determined the presence of typical RNA pol III sequence motifs. The porcine 7SK (po7SK) promoter was cloned and a one-step PCR strategy used to construct shRNA expression cassettes. The 7SK promoter activity was quantified by knockdown of the exogenous reporter gene encoding the enhanced green fluorescent protein (EGFP). Results indicated the po7SK promoter was functional in both homologous and heterologous cells lines. The identification and characterisation of the porcine RNA pol III promoter will contribute to the area of RNAi delivery and further develop our understanding of RNA promoter structure and function.

Oncogenic properties of HIV-Tat in colorectal cancer cells

With the advent of Highly-Active-Anti-Retroviral-Therapy (HAART), HIV patients can expect to live beyond 10-15 years following diagnosis. An unexpected result of increased survival is the emergence of opportunistic, oncogenic virus-associated cancers such as Burkitt's lymphoma (Epstein-Barr Virus), cervical cancer (Human Papilloma Virus) and Kaposi's sarcoma (Kaposi's sarcoma-associated herpesvirus) in this immuno-compromised population. Furthermore, there are reports of colorectal cancers (CRC) in long-term HIV-AIDS survivors. Compared to the general, non-immuno-compromised population, long-term AIDS patients have 4 and 3.3-fold increased risk of developing colorectal and anorectal cancer respectively. Unlike oncogenic virus-associated cancers, CRC is not known to have a viral etiology. Our study aimed to investigate one aspect of HIV infection and colorectal carcinogenesis. We proposed that the HIV transactivator protein Tat; a protein with known oncogenic properties that is secreted and can re-enter non-infected cells may have a role in CRC. Using two CRC cell lines, LIM1215 and LIM2537 we found that Tat inhibits epithelial cyto-differentiation, blocks apoptosis in vitro and accelerates tumour formation in vivo. In addition, Tat significantly increases in vitro migration in the absence of foetal calf serum. These properties underpin CRC, and as HIV infection is initiated in the gut lymphoid system, these data provide a basis for the increased incidence of CRC in long term AIDS patients.

Mutations in the MYB intron I regulatory sequence increase transcription in colon cancers

Although MYB overexpression in colorectal cancer (CRC) is known to be a prognostic indicator for poor survival, the basis for this overexpression is unclear. Among multiple levels of MYB regulation, the most dynamic is the control of transcriptional elongation by sequences within intron 1. The authors have proposed that this regulatory sequence is transcribed into an RNA stem-loop and 19-residue polyuridine tract, and is subject to mutation in CRC. When this region was examined in colorectal and breast carcinoma cell lines and tissues, the authors found frequent mutations only in CRC. It was determined that these mutations allowed increased transcription compared with the wild type sequence. These data suggest that this MYB regulatory region within intron 1 is subject to mutations in CRC but not breast cancer, perhaps consistent with the mutagenic insult that occurs within the colon and not mammary tissue. In CRC, these mutations may contribute to MYB overexpression, highlighting the importance of noncoding sequences in the regulation of key cancer genes.

Construction and expression of a Rev-dependent TNF-R1 expressing HIV-infected-cell injurious vectors

BACKGROUND

Rev is necessary for exporting unspliced and incompletely spliced intron containing HIV mRNAs and for HIV replication. The aim of this study is to develop a kind of selective suicide construct that can specifically and directly induce HIV infected cells into apoptosis based on the high affinity of Rev and Rev response element (RRE).

METHODS

Molecular-cloning technique was used to synthesis Rev dependent TNF-R1 expression construct pDM128-TNF-R1 (pT128) that contains RRE and TNFR1 gene. Restriction digestion, Polymerase Chain Reaction (PCR) and DNA sequencing were processed and the exactness and correctness of the inserted TNF-R1 gene in pT128 were confirmed repeatedly. The expression of pT128 co-transfected with different combination of other plasmids by calcium phosphate-DNA co-precipitation in Helas and by gene gun transfection in keratinocytes was further tested by flow-cytometry and cell counted under microscope.

RESULTS

The new plasmid specifically expressed TNF-R1 in Helas when co-transfected with pRev but did not when without pRev. Indirect expression of TNF-R1 from pT128 was slower than the direct expression of that from Hu p60 TNFR1 in pDC302 (pT60), but all those pT60 or pT128 transfected cells showed apoptosis at last while TNF-R1 was sufficiently expressed. Other kinds of Rev expression construct such as pAD8 and a chimeric HIV vaccine also can switched on the selective expression of pT128. Not only Rev-dependent expression in Helas, pT128 also normally expressed its TNF-R1 in keratinocytes. Co-transfected with pRev or pAD8 that expressed Rev, pT128 expressed TNF-R1 and induced apoptosis of green fluorescent keratinocytes in skin explant. The number of green fluorescent keratinocytes co-transfected by pT128 plus pRev or pAD8 was gradually outnumbered by that co-transfected by pT128 only. The difference was more significant after culturing for 72 hours.

CONCLUSIONS

Rev dependent pT128 is able to selectively induce apoptosis of HIV-infected or Rev-expressed target cells by expression of TNF-R1. The new strategy based on manipulation of the regulatory protein of HIV may be valuable in design of new HIV vaccine.

Childhood sexual abuse and sexual transmission risk behaviour among HIV-positive men who have sex with men

Previous studies have indicated an association between childhood sexual abuse (CSA) and adult sexual risk behaviour among women and among men who have sex with men (MSM). However, no studies to date have tested the hypothesis that a history of CSA predicts sexual behaviour carrying risk of transmission of HIV to others, i.e. in a known HIV-positive cohort. The present study tested this hypothesis among a sample of 456 HIV-positive MSM recruited from community venues in New York and San Francisco. CSA history was found to be significantly associated with past (in the last 90 days) unprotected anal sex acts, both insertive (33% versus 20%, p < 0.05) and receptive (43% versus 27%, p < 0.02), with partners of HIV-negative or unknown serostatus. Further, several potential mediators of this effect were tested, and three found to be predicted by CSA history. Each of these potential mediators was associated with sexual risk behaviour, but differentially: anxiety and hostility were significantly associated with insertive acts, while anxiety, hostility and suicidality were associated with receptive acts. Mediation analyses supported the hypothesis that these factors significantly (albeit partially) accounted for the association of CSA with receptive anal intercourse. Nonsignificant mediation effects were found for insertive sex, suggesting the operation of unmeasured mediating variables. These results highlight the importance of mental health services for individuals who have been sexually abused, both for personal and for public health benefit, and also indicate a need for further research into mediators of CSA effects on transmission-related behaviour.

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.

Objective calibration of bone conductors using otoacoustic emissions

OBJECTIVE

To demonstrate a technique for objectively calibrating bone conductors on an individual basis using distortion product otoacoustic emissions (DPOAEs).

DESIGN

Individual calibrations were obtained using DPOAEs recorded from a single ear of 21 normally hearing adults. Validity and robustness of the technique were investigated through subjective phase cancellation measurements and sensitivity analysis.

RESULTS

Calibrations obtained using the DPOAE method were well supported by phase cancellation results. Intersession repeatability was good, and manipulation of the DPOAE data showed that the calculated calibration is relatively insensitive to small variations of emission magnitude. Bilateral stimulation through bone conduction did not display an apparent effect on emission magnitude in a single individual.

CONCLUSION

Bone conductors can be accurately calibrated on an individual basis with good repeatability using DPOAEs. The technique is robust and offers an objective, noninvasive calibration method for research and specialized clinical applications. No training and only passive cooperation are required, making the procedure ideal for special groups such as children. A number of limitations will reduce the clinical utility of this technique. Important audiometric frequencies below 1 kHz cannot be tested because of noise, because individuals with significant hearing loss are unlikely to produce sufficient DPOAEs, and because commercial bone conductors typically have poor high-frequency response above 4 kHz.

Suicide among the elderly in Honolulu County: a multiethnic comparative study (1987-1992)

Suicide rates for the elderly continue to be the highest for any age group. Although these rates are known to be significant, little study has been given to the ethnic variability associated with this phenomenon. This retrospective study was undertaken to explore this issue and involved a review of the coroner's reports for completed elder suicides (65 years of age or older) for Honolulu County from 1987 through 1992 inclusive. The results showed a mean age of 75 years, with the highest incidence of completion in the 80+ age group. The predominant method of suicide completion in this study group was found to be hanging, followed by jumping, firearms, and poisoning. There were significant gender and ethnic differences in the method of suicide completion. Almost half of the sample saw a healthcare provider within the 6 months before their death. Comparisons with other elder suicide studies are presented.

Distortion product otoacoustic emissions stimulated through bone conduction

OBJECTIVE

To demonstrate the viability of bone conduction as a novel method for stimulation of distortion product otoacoustic emissions (DPOAEs).

DESIGN

DPOAEs were recorded from a single ear of 23 normally hearing adults using bone and air conduction for the delivery of stimulus tones. Exploration of the input-output function was performed by varying stimulus frequency and magnitude.

RESULTS

Bone-stimulated emissions demonstrated similar characteristics to those obtained through standard air transmission techniques. Characteristic nonlinear DPOAE growth was found as the magnitude of the higher frequency stimulus tone, L2, was increased monotonically with other parameters fixed. Bilateral stimulation due to using bone conduction did not saturate the mechanisms of emission suppression. Emission magnitude was not altered substantially by occlusion of the ear canal.

CONCLUSION

Bone conduction can be used successfully to elicit DPOAEs. Absolute comparison of air- and bone-stimulated DPOAEs was difficult because of imprecise calibration of the bone conductors for each individual and particular placement. Properties unique to bone conduction, such as simultaneous bilateral stimulation and reduction of stimulus magnitude in the ear canal, may make bone conduction attractive for clinical measurement of DPOAEs.

Restricted HIV-1 infection of human astrocytes: potential role of nef in the regulation of virus replication

A small percentage of astrocytes are consistently infected in vivo by HIV-1 and may contribute to neuropathogenesis despite a non-productive infection. Overexpression of the nef gene product has been associated with their infection both in vivo and in vitro. We examined the role of the nef gene during HIV replication in astrocytes (U251MG cells) following transfection with pNL4-3 proviral plasmid or isogenic strains containing a deletion or point mutation in the nef gene (pNL4-3deltaNef; pNL4-3-nef-stop). We were able to initiate virus replication which peaked at 5 days post-transfection and became non-productive after 21 days. Nef protein expression by wild type pNL4-3 was observed at low levels compared to control HeLa cells at peak virus replication. At later time points after development of a non-productive infection, viral antigen and Nef protein was not detectable however virus was readily recovered by co-culture with CD4+T-cells. Interestingly, virus production was significantly enhanced by a 222 base pair deletion in the nef reading frame. This was not observed with a frame shifting point mutation in nef, indicating a suppressive effect of nef on virus production in astrocytes. The enhanced virus production from nef-deleted pNL4-3 in U251MG cells was not reversed by co-expression of Nef from a second Nef-expressing plasmid, and in fact Nef expression in trans had a further positive effect on virus production. This suggested opposing effects of the Nef protein and elements contained within the nef sequence on virus production in astrocytes. Despite the low expression of Nef by U251MG astrocytes, relatively high amounts of multiply spliced 2 kb mRNA were present compared to HeLa cells. These data demonstrate that an acute low-level infection of astrocytes rapidly becomes a non-productive infection and this process is assisted by sequences in nef. The low level Nef protein expression, despite high levels of mRNA, suggests a block in translation of multiply spliced HIV mRNA in astrocytes, or a translational control mechanism not yet characterised.

Myopathy and spontaneous Pasteurella pneumotropica-induced abscess formation in an HIV-1 transgenic mouse model

In an effort to augment human immunodeficiency virus type 1 (HIV-1) gene expression in transgenic mice, an infectious proviral DNA clone was modified by deleting the two NF kappa B binding sites and some adjacent upstream LTR sequences and replacing them with the core enhancer of Moloney murine leukemia virus (MLV). Two independent lines of MLV/HIV transgenic mice were established that expressed HIV-1-specific RNA in lymphoid tissue, striated skeletal muscle, and the eye lens. Heterozygous animals from each transgenic line spontaneously developed an inflammatory disease of the eye associated with the production of copious amounts of purulent lacrimal secretions beginning at 2 weeks of age. Periorbital abscess formation became grossly apparent by 2 months of age and Pasteurella pneumotropica was cultured from the harderian glands and conjunctival surfaces of many of the MLV/HIV animals but not their nontransgenic, cohabiting littermates. This gram-negative commensal bacterium has been previously associated with a similar disease phenotype in immunocompromised (e.g., nude mice) rodent colonies. MLV/HIV mice developed normally until 15 weeks of age, when weight loss and wasting occurred, culminating in premature death (as earlier as 6 months of age). The cachexia was associated with an initially focal and subsequently progressive myopathy, coinciding with age-related increases of HIV gene expression in muscle.

Effect of poultry waste feeding on intake, body weight and milk yield of Holstein cows

Forty lactating Holstein cows were fed 0, 5.9, 11.7, or 17.4% processed poultry excreta in total mixed rations. The effect of treatment was evaluated on feed intake, BW, milk yield, and composition. Processes poultry excreta appeared to be well accepted by cows even when included in rations at 17.4% of total DM. Mean DM intake averaged 19.3, 19.7, 19.5, and 19.7 kg/d for cows fed 0, 5.9, 11.7, and 17.4% processed poultry excreta, respectively. Body weight change averaged 2.0, 1.7, -1.7, and 1.4 kg/wk from 90 to 180 d of lactation for cows fed from 0 to 17.4% processed poultry excreta, respectively. Fat-corrected milk (4%) yield was similar among treatment groups, averaging 24.2, 26.1, 24.6, and 25.1 kg/d for cows fed 0, 5.9, 11.7, and 17.4% processed poultry excreta. No differences were found for milk and fat yields of percentage fat among treatment means. No off flavors in milk could be attributed to processed poultry excreta added to feed. Processed poultry excreta fed up to 17.4% of total mixed rations supported both adequate feed intake and high milk yields of mid-lactation cows.

Routine intraoperative angioscopy in lower extremity revascularization

The inability to see through blood remains the main obstacle to the widespread and routine use of angioscopy. Local irrigation with a balanced salt solution is presently the most widely used method to clear the blood. By applying basic principles of irrigation and using a unique, dedicated, irrigation pump, we found that routine angioscopy during lower extremity revascularization that yields consistent high-quality studies is feasible, clinically useful, and safe. Between May 1, 1987, and July 31, 1988, 136 intraoperative angioscopies were performed during 112 peripheral bypass procedures, 15 thrombectomies, 2 embolectomies, and 7 miscellaneous revascularization procedures. Mean total irrigation fluid used in the peripheral bypasses was 398 mL (range, 0 to 1400 mL). Good visual quality was obtained in more than 80% of angioscopies and the failure rate was only 1.8%. On the basis of the findings in 71 of the 136 angioscopies, 78 clinical or surgical decisions were made. No complications were directly attributable to the insertion of the angioscope or use of the pump.

Does integration produce masking or protect from it?

To examine the role of integration in pattern masking, possible disruptive effects of integration were minimized by using a mask that overlaid completely all targets. Exposure durations were 10 ms, so under energy summation the target area was much darker than the rest. In another condition the mask was red and targets were blue, so under energy summation the target area could also be distinguished by hue. Masking magnitude increased with delay of mask onset, and it was established by four independent criteria that integration was negligible in the condition which produced most masking. It is deduced that integration is not necessary for masking; furthermore it is suggested that integration never produces masking, but rather may or may not protect from a disruptive effect of interruption. The argument is that were the visual system to have better visual resolution, it would suffer more given the same masking parameters. It is argued that type B masking functions arise from a combination of the facilitatory effect of integration and the detrimental effect of interruption.