Synergistic neutralization of a chimeric SIV/HIV type 1 virus with combinations of human anti-HIV type 1 envelope monoclonal antibodies or hyperimmune globulins

A panel of 14 human IgG monoclonal antibodies (MAbs) specific for envelope antigens of the human immunodeficiency virus type 1 (HIV-1), 2 high-titer human anti-HIV-1 immunoglobulin (HIVIG) preparations, and 15 combinations of MAbs or MAb/HIVIG were tested for their ability to neutralize infection of cultured human T cells (MT-2) with a chimeric simian immunodeficiency virus (SHIV-vpu+), which expressed HIV-1 IIIB envelope antigens. Eleven MAbs and both HIVIGs were neutralizing. When used alone, the anti-CD4-binding site MAb b12, the anti-gp41 MAb 2F5, and the anti-gp120 MAb 2G12 were the most potent. When combination regimens involving two MAbs targeting different epitopes were tested, synergy was seen in all paired MAbs, except for one combination that revealed additive effects. The lowest effective antibody concentration for 50% viral neutralization (EC50) and EC90 were achieved with combinations of MAbs b12, 2F5, 2G12, and the anti-V3 MAb 694/98D. Depending on the combination regimen, the concentration of MAbs required to reach 90% virus neutralization was reduced approximately 2- to 25-fold as compared to the dose requirement of individual MAbs to produce the same effect. Synergy of the combination regimens implies that combinations of antibodies may have a role in passive immunoprophylaxis against HIV-1. The ability of SHIV to replicate in rhesus macaques will allow us to test such approaches in vivo.

Identification of a synthetic peptide that mimics an HIV glycoprotein 120 envelope conformational determinant exposed following ligation of glycoprotein 120 by CD4

CD4 ligation of HIV envelope gp120 results in conformational changes in gp120 that lead to exposure of the gp41 fusogenic domain and fusion with the host cell membrane. One determinant at or near the CD4-binding site exposed on gp120 subsequent to CD4 binding is defined by two human MAbs termed 17b and 48d. These MAbs do not block CD4 binding to gp120; rather, their binding to gp120 is upregulated following CD4 binding. To determine if synthetic peptide mimetopes could be found that reflect conformational determinants on the surface of gp120, synthetic gp120 peptides from 10 divergent HIV isolates were screened for their ability to bind to 17b and 48d in ELISAs. Although MAb 48d binds to HIV IIIB recombinant gp120 protein, in our studies 48d selectively bound only to the HIV Can0A V3 peptide and not to HIV IIIB V3 peptide, whereas MAb 17b bound none of the peptides tested. Monoclonal antibody 48d bound to the HIV Can0A V3 peptide both in solid-phase ELISA and in solution in a competitive ELISA, but could not bind to HIV Can0A V3 peptide bound to human T cells. The HIV Can0A V3 peptide induced anti-HIV antibodies in rhesus monkeys that neutralized the laboratory-adapted HIV MN strain but did not induce antibodies that neutralized HIV IIIB/LAI, HIV SF-2, or HIV RF isolates, or that neutralized HIV primary isolates. These data suggested that the primary sequence of the HIV Can0A V3 loop exists in a conformer that mimicks a non-V3 determinant of native gp120 exposed subsequent to CD4 binding on the surface of gp120 of laboratory-adapted HIV strains. Structural studies of the Can0A V3 peptide and/or the 48d MAb may provide important information regarding the nature of gp120 conformational changes that occur following gp120 ligation by CD4.

Combination treatment with zidovudine, didanosine, and nevirapine in infants with human immunodeficiency virus type 1 infection

BACKGROUND

In infants and children with maternally acquired human immunodeficiency virus type 1 (HIV-1) infection, treatment with a single antiretroviral agent has limited efficacy. We evaluated the safety and efficacy of a three-drug regimen in a small group of maternally infected infants.

METHODS

Zidovudine, didanosine, and nevirapine were administered in combination orally to eight infants 2 to 16 months of age. The efficacy of antiretroviral treatment was evaluated by serial measurements of plasma HIV-1 RNA, quantitative plasma cultures, and quantitative cultures of peripheral-blood mononuclear cells.

RESULTS

The three-drug regimen was well tolerated, without clinically important adverse events. Within four weeks, there were reductions in plasma levels of HIV-1 RNA of at least 96 percent (1.5 log) in seven of the eight study patients. Over the 6-month study period, replication of HIV-1 was controlled in two infants who began therapy at 2 1/2 months of age. Plasma RNA levels were reduced by 0.5 to 1.5 log in five of the other six infants.

CONCLUSIONS

Although further observations are needed, it appears that in infants with maternally acquired HIV-1 infection, combined treatment with zidovudine, didanosine, and nevirapine is well tolerated and has sustained efficacy against HIV-1.

Psychosocial adjustment to unsuccessful IVF and GIFT treatment

Twenty-one couples for whom in vitro fertilisation (IVF) or GIFT treatment failed were followed-up 15-30 months after treatment and compared with 20 couples for whom IVF had been successful. Current mental health status, quality of life and marital adjustment were assessed via standardised questionnaires. In addition, couples' experiences of IVF/GIFT treatment were explored via a semi-structured interview. Questionnaire results showed that unsuccessful IVF/GIFT recipients cannot be distinguished from general population norms. However, these couples reported more emotional distress relative to those whom treatment had worked and females in particular indicated a lower quality of life. Couples who had at least one child prior to IVF/GIFT treatment tended to show greater emotional distress at follow-up. Both groups gave similar accounts of the positive and negative aspects of IVF/GIFT treatment, but the unsuccessful group felt less supported by the IVF Unit staff and were less satisfied with the counseling they received. The data indicate that post-treatment counseling may be particularly important for facilitating positive reconstructions of the IVF experience when treatment is unsuccessful.

Remote monitoring. Expanding a successful system

A successful telemetry placement system moves into five medical/surgical areas and two step-down units. The updated equipment included an alarm gateway with an arrhythmia detection system. Telemetry signals are transmitted to a pager worn by nurses; remote display monitors allow nurses to eyeball arrhythmias and reset their alarm without going to a central station.

Investigation of the association between the presence of cytoplasmic residues on the human sperm midpiece and defective sperm function

Defective sperm function has been identified as one of the most common causes of human infertility. The aim of this investigation was to identify whether the presence of retained cytoplasm on the human sperm midpiece is associated with defective sperm function. Statistical analysis of data demonstrated a strong negative correlation between the presence of residual cytoplasm on the midpiece of spermatozoa in the inseminate and fertilization rate during IVF. Significant negative correlations were also identified between the percentage of spermatozoa in the ejaculate bearing cytoplasmic residues and (i) spermatozoa having membrane integrity and (ii) sperm concentration. A highly significant positive correlation was also revealed between the percentage of spermatozoa in the ejaculate with membrane integrity and the percentage of motile spermatozoa. These correlations suggest that retained cytoplasm is a cause of subfertility. Measurements of the percentage of spermatozoa bearing residual cytoplasm in the IVF inseminate could provide the basis for a simple predictive test before IVF.

Valaciclovir for the suppression of recurrent genital HSV infection: a placebo controlled study of once daily therapy. International Valaciclovir HSV Study Group

OBJECTIVE

To determine the efficacy and safety of once daily valaciclovir for the suppression of recurrent genital herpes simplex virus (HSV) infection in immunocompetent patients.

METHODS

382 otherwise healthy patients with a history of frequently recurring genital HSV infection (eight recurrences per year) were randomly allocated to receive either oral valaciclovir (500 mg once daily) or placebo (3:1 ratio) for 16 weeks or until the first genital HSV recurrence, whichever occurred first. Patients were clinically assessed at regular intervals and also if they experienced a recurrence. Safety was evaluated through adverse experience reporting and monitoring of haematology and biochemistry variables. On completion of the double blind phase, patients were eligible for follow up to a maximum of 48 weeks' treatment with open label valaciclovir (500 mg once daily) for further safety monitoring. The results from the double blind phase of the study are reported here.

RESULTS

A significant difference was detected between valaciclovir and placebo in the time to first recurrence of genital HSV infection. The hazard ratio [95% confidence interval] for valaciclovir v placebo was 0.155 [0.112, 0.214], p < 0.0001. Valaciclovir prevented or delayed 85% of the recurrences that would have occurred with placebo. After 16 weeks (day 112) with treatment, 69% of patients receiving valaciclovir were recurrence free compared with only 9.5% of patients assigned to placebo. The safety profiles of valaciclovir and placebo were comparable, with adverse experiences being infrequent and generally mild.

CONCLUSION

This study has demonstrated that once daily valaciclovir (500 mg), is highly effective and well tolerated for the suppression of recurrent genital HSV infection. Once daily dosing with valaciclovir provides a more convenient dosing regimen than the more frequent aciclovir regimens.

Oral L-arginine improves endothelium-dependent dilatation and reduces monocyte adhesion to endothelial cells in young men with coronary artery disease

L-Arginine is the physiological substrate for nitric oxide synthesis by the vascular endothelium. In hypercholesterolaemic rabbits, oral L-arginine reduces atheroma, improves endothelium-dependent dilatation and reduces monocyte/endothelial cell adhesion. The effect of oral L-arginine on endothelial physiology is unknown, however, in humans with established atherosclerosis. In a prospective, double-blind, randomised crossover trial, ten men aged 41 +/- 2 years with angiographically proven coronary atherosclerosis took L-arginine (7 g three times per day) or placebo for 3 days each, with a washout period of 10 days. After L-arginine, compared to placebo, plasma levels of arginine were increased (318 +/- 18 vs. 124 +/- 9 mumol/l, P < 0.01) and endothelium-dependent dilatation of the brachial artery (measured as the change in diameter in response to reactive hyperaemia, using external vascular ultrasound) was improved (4.7 +/- 1.1 vs. 1.8 +/- 0.7%, P < 0.04). No changes were seen in endothelium-independent dilatation of the brachial artery (measured as the change in diameter in response to sublingual nitroglycerine), blood pressure, heart rate or fasting lipid levels. Serum from six of the ten subjects after L-arginine and placebo was then added to confluent monolayers of human umbilical vein endothelial cells for 24 h, before human monocytes obtained by countercurrent centrifiguation elutriation were added and cell adhesion assessed by light microscopy. Adhesion was reduced following L-arginine compared to placebo (42 +/- 2 vs. 50 +/- 1%, P < 0.01). In young men with coronary artery disease, oral L-arginine improves endothelium-dependent dilatation and reduces monocyte/endothelial cell adhesion.

Does ribavirin impact on the hospital course of children with respiratory syncytial virus (RSV) infection? An analysis using the pediatric investigators collaborative network on infections in Canada (PICNIC) RSV database

OBJECTIVES

To determine the relationship between receipt of aerosolized ribavirin and the hospital course of high-risk infants and children with respiratory syncytial virus (RSV) lower respiratory infection (LRI).

METHODS

The 1993-1994 Pediatric Investigators Collaborative Network on Infections in Canada (PICNIC) RSV database consists of prospectively enrolled children with acute RSV LRI, admitted to nine Canadian pediatric tertiary care centers. After excluding cases with compromised immunity and/or nosocomial infection, subsets with any congenital heart disease (CHD), chronic lung disease (CLD), age </=6 weeks (INFANT), gestation </=36 weeks (PREM), or severe disease within 48 hours of admission as shown by an oxygen saturation </=90% or an FiO2 requirement of >.35 (EARLY HYPOXIA) were studied in two ways. First, each risk group subset was analyzed separately to assess the association between ribavirin receipt and measures of disease severity including duration of intensive care, mechanical ventilation, hypoxia and RSV-attributable hospital stay. Secondly, ribavirin was added as an independent variable to a previously described multiple regression model for RSV-attributable length of hospital stay and two mutually exclusive subsets were analyzed: 1) previously healthy patients with >/=1 of: INFANT, PREM, or EARLY HYPOXIA; 2) patients with CHD and/or CLD.

RESULTS

Between January 1993 and June 1994, 1425 community-acquired hospitalized cases of RSV LRI were entered into the RSV database. Among these 750 (52.6%) fit into one or more of the defined subsets including 97 CHD, 134 CLD, 213 INFANT, 211 PREM, and 463 EARLY HYPOXIA. The proportion ventilated in each group was 20.6%, 20.9%, 15.5%, 15.2%, and 13.3%, respectively. Across the subsets ribavirin use ranged from 36% to 57% of ventilated patients and 6% to 39% of nonventilated patients. For nonventilated patients in each subset the median RSV-attributable hospital length of stay (RSV-LOS) was 2 to 3 days longer for ribavirin recipients and the duration of hypoxia was significantly increased. Duration of intensive care unit (ICU) stay was also increased for all ribavirin-treated subgroups except those with CHD. In contrast, for ventilated patients, ribavirin therapy was not significantly associated with any of the outcome measures regardless of risk group. In the multiple regression model, ribavirin was significantly associated with a prolonged RSV-LOS both for children with CHD and/or CLD as well as for those whose only risk factors included INFANT, PREM, and/or EARLY HYPOXIA.

CONCLUSIONS

These data raise further doubts about the clinical effectiveness of ribavirin in infants and children with risk factors for severe disease. Selection bias, with ribavirin used for sicker children, may have influenced outcome. Nevertheless the long durations of hospitalization, ICU, ventilation, and oxygen supplementation in nonventilated ribavirin recipients stress the need for further randomized trials to assess its efficacy.

The Pyloritek test and the CLO test: accuracy and incremental cost analysis

OBJECTIVE

The aim of this study was to compare the Pyloritek test (a 1-h rapid urease test) to the widely used CLO test.

METHODS

Seventy-one patients undergoing upper endoscopy were studied. All patients gave informed consent. A single antral biopsy specimen was obtained for the CLO test, and another was obtained for the Pyloritek test. Additional specimens were obtained for culture and processed in the event of a discordant result. The Pyloritek assay was read at 1 h by one observer. The CLO test was read at 24 h by an observer blinded to the results of the Pyloritek assay.

RESULTS

There were 18 males and 53 females, and the mean age (+/- SEM) was 53 +/- 17 yr. Thirty-two patients had a positive result on the CLO test, and 39 had a negative test result. Of the 32 patients with a positive CLO test result at 24 h, 31 were positive by the Pyloritek test at 1 h. All 39 patients with negative CLO test results had negative Pyloritek test results as well. There was one discordant result, a negative Pyloritek test result and a positive CLO test result. Culture demonstrated growth of Helicobacter pylori. The kappa value, a measure of the reliability of the Pyloritek test compared with the CLO test, was 0.972 (SE, 0.0284; 95% confidence interval, 0.925-1). Marginal cost-effectiveness analysis favored the Pyloritek test.

CONCLUSIONS

Results of the Pyloritek test at 1 h and the CLO test at 24 h are comparable in terms of detection of urease activity.

A model for the maturation of protective antibody responses to SIV envelope proteins in experimentally immunized monkeys

Studies using live attenuated virus vaccines in the simian immunodeficiency virus (SIV) rhesus macaque model have demonstrated broad protection against experimental challenge. Protection in these studies was found to be critically dependent on the length of time postvaccination, suggesting that protective immunity involves a necessary maturation of immune responses. The current study characterizes the evolution of protective envelope-specific antibody responses from monkeys inoculated with the highly attenuated SIV/17E-Cl virus vaccine. For comparison, the same antibody assays were used to characterize the properties of SIV envelope-specific antibodies elicited by inactivated whole virus and envelope subunit vaccines that failed to provide protection from experimental virus challenge. Results of these studies identify a continuous and complex maturation of envelope-specific antibody responses during the first six to eight months postinfection. Furthermore, the time required for maturation of SIV envelope-specific antibodies parallels the time required for the development of protective immunity against experimental challenge with heterologous strains of SIV. While no single immune correlate of protection has been identified, we suggest that a combination of antibody parameters may serve as prognostic indicators in the development of candidate AIDS vaccines.

An anatomic study of the internal mammary veins: clinical implications for free-tissue-transfer breast reconstruction

The anatomy of the internal mammary vessels is poorly understood and thought to be unreliable clinically for use as a recipient vein in free-tissue-transfer breast reconstruction. This study of 10 fresh cadaver thoracic cavities demonstrated by anatomic and dye resection studies that the internal mammary veins become smaller (< or = 2 mm) distally (fourth rib) and bifurcate [left (90 percent) > right (40 percent)], becoming unsuitable for consistent venous anastomoses at or below the fourth interspace. Furthermore, this study suggests that the most consistent interval is the third rib, which offers an appropriate recipient vein (40 percent > or = 3 mm on the left and 70 percent > or = 3 mm on the right). However, at the fourth interspace, 20 percent of the cadaver specimens had a vein on one side that was 1 mm or less and therefore unsuitable as a recipient. This enhanced understanding of the anatomy (size, location, and consistency) of the internal mammary recipient veins offers our patients another recipient option to enhance the safety and technical ease of microvascular breast reconstruction.

Characterization of adult alpha- and beta-globin genes in the zebrafish

Developmental switching of hemoglobins (Hbs) occurs in most vertebrates, yet the cellular and molecular basis for this process remains elusive. The zebrafish is a new genetic and developmental system that can be used to study embryogenesis, and mutants with a variety of defects in hematopoiesis have recently been derived. To initiate our studies on Hb switching in this organism, we have characterized the globins expressed in the adult. Reversed-phase high performance liquid chromatography and mass spectrometric analyses of adult peripheral blood hemolysates showed that there are three major alpha globins and two beta globins in circulating erythroid cells. In addition, we have isolated and characterized zebrafish adult alpha- and beta-globin cDNA clones that encode some of these globins. High levels of alpha- and beta-globin gene expression were detected in adult erythroid cells, whereas embryonic erythroid cells expressed little, if any, of these RNAs. We have also shown that the alpha- and beta-globin genes are tightly linked on the same chromosome and are arrayed in a 3'-5' to 5'-3' configuration, respectively. The characterization of these genes and regulatory elements in this globin locus will provide insight into the process of globin gene transcription. With these reagents, future studies of Hb switching in zebrafish mutants with defective hematopoiesis will be possible.

A longitudinal twin study of intelligence in the second year

Data from 408 pairs of identical and same-sex fraternal twins assessed at home and in the laboratory at 14, 20, and 24 months are used to describe cognitive development in the second year and to identify genetic and environmental influences on phenotypic similarity. The primary dependent variables are the Bayley Mental Development Index and separate constructs (based on items from the Bayley and the Sequenced Inventory of Communication Development) to measure nonverbal ability, expressive language, and receptive language. These variables are supplemented with laboratory tests of word comprehension, visual attentiveness, and memory for locations. Various patterns of development emerge for separate constructs, for females versus males on each construct, and for individuals across constructs. These data suggest developmental transitions for many infants during the second year, but the timing of these transitions varies by measure. The dependent variables tend to be intercorrelated and are reasonably stable for individuals, with greater stability late in the second year, suggesting either increasing stability or more effective measurement. Expressive and receptive language scores are correlated and have comparable patterns of change within individuals, but there are also differences (e.g., receptive language accounts for the most variance in MDI at each age and across ages). There are genetic effects on MDI at each age and effects of shared environment at 20 and 24 months. Analyses of separate constructs reveal distinct patterns. Effects on nonverbal abilities are entirely genetic. Effects on language are primarily environmental, but genetic influence emerges for expressive language at 20 and 24 months and for receptive language at 14 months. Visual attentiveness tended to reveal effects comparable to the nonverbal construct, and word comprehension was related to the receptive composite. Scores on the memory for locations task were relatively uninformative. A Cholesky decomposition is used to identify influences that account for the same variance at each age (i.e., promote continuity) and that account for new variance at each assessment (i.e., promote change) and to explore overlap and distinctiveness among measures at each age.

Flow cytometric HLA-B27 typing using CD3 gating and molecules of equivalent soluble fluorochrome (MESF) quantitation

The determination of HLA-B27 (B27) status is important in the diagnosis of ankylosing spondylitis, Reiter's disease, and other arthropathies. Flow cytometric (FCM) typing of B27 is a relatively new method which allows for rapid turnaround time and low cost. However, different leukocyte populations may manifest significant variation in staining intensity with B27 antibodies. Therefore, gating utilizing only light scatter properties of cells may lead to high readings in some B27-negative samples. Fluorescence gating on CD3+ cells were postulated as a means to eliminate these anomalies. Furthermore, quantitative FCM measurements, as afforded through use of molecules of equivalent soluble fluorochrome (MESF) units, can minimize day-to-day and instrument-to-instrument variabilities in fluorescence measurements. We compared CD3 gating to light scatter gating and MESF analysis on 123 specimens in a 4-month period and found: 1) CD3 gating gave the lowest nonspecific B27 antibody binding among B27-negative subjects; 2) there was no significant difference in MESF values between CD3 gating and light scatter gating of B27-positive samples; 3) there was a wide range of B27 antibody binding fluorescence intensities among B27-positive subjects; 4) identification of patients with low B27 expression may require the use of CD3 gating in order to avoid costly confirmation testing; 5) fluorescent standard beads are stable for routine use in a clinical flow cytometry laboratory.

The protective action of polyvinylpyrrolidone-Percoll during the cryopreservation of mouse 2-cell embryos and its effect on subsequent developmental potential post-thaw in vitro and in vivo

The effects of cryopreservation, in media containing (FS3+) or omitting (FS3) polyvinylpyrrolidone (PVP) in the form of Percoll (PVP-Percoll), on the survival of 2-cell mouse embryos was studied. Survival and zona pellucida disruption post-thaw, growth (assessed by in-vitro culture until the blastocyst stage) and development in vivo (assessed by implantation and living fetus rates and the birth of live progeny) were all investigated. Initial post-thaw survival showed no statistically significant difference (P > 0.05) between FS3+ (91.1 +/- 9.8%) and FS3 (84.5 +/- 6.6%). However, there was a statistically significant (P < 0.05) reduction in the incidence of zona damage when the freezing solution contained PVP-Percoll compared to the control (3.6 +/- 1.0 and 8.7 +/- 0.6% respectively) and a statistically significant (P < 0.05) greater number of embryos developing in vitro to the blastocyst stage (84.8 +/- 7.1 and 72.3 +/- 6.1% respectively). The rates of implantation were not significantly different: 72.2 +/- 7.0% for FS3+ and 51.2 +/- 30.7% for the non-frozen control group. The percentage of live fetuses was also similar between the experimental and control groups: 27.4 +/- 10.6 and 24.3 +/- 11.3% respectively. We conclude that the presence of polymers can protect embryos against cryoinjury and that PVP in the form of PVP-Percoll provides a non-toxic alternative to PVP in its native form, during the cryopreservation of mouse 2-cell embryos.

Fluorescence spectral properties of troponin C mutant F22W with one-, two-, and three-photon excitation

We report the first measurements of protein fluorescence with three-photon excitation, using a mutant of troponin C (TnC) that contains a single tryptophan residue F22W. From the emission intensity dependence on laser power we determine that TnC F22W displays one-, two-, and three-photon excitation at 285, 570, and 855 nm, respectively. The emission spectra and intensity decays are identical for one-, two-, or three-photon excitation. The steady-state and time 0 anisotropies are distinct for each mode of excitation, but the correlation times were the same, suggesting that three-photon excitation of proteins can be accomplished without significant effects of the locally intense illumination. The excitation anisotropy spectrum from 830 to 900 nm displays only negative values, suggesting dominant excitation via the 1Lb state of tryptophan from 830 to 900 nm.

Resistance of human immunodeficiency virus type 1 to neutralization by natural antisera occurs through single amino acid substitutions that cause changes in antibody binding at multiple sites

The ability of human immunodeficiency virus type 1 (HIV-1) to replicate in the presence of strong immune responses to the virus may be due to its high mutation rate, which provides envelope gene variability for selection of neutralization-resistant variants. Understanding neutralization escape mechanisms is therefore important for the design of HIV-1 vaccines and our understanding of the disease process. In this report, we analyze mutations at amino acid positions 281 and 582 in the HIV-1 envelope, where substitutions confer resistance to broadly reactive neutralizing antisera from seropositive individuals. Neither of these mutations lies within an antibody-binding site, and therefore the mechanism of immune escape in both cases is by alteration of the shape of the envelope proteins. The conformation of the CD4-binding site is shown to be critical with regard to presentation of other discontinuous epitopes. From our analysis of the neutralization of these variants, we conclude that escape from polyclonal sera occurs through alterations at several different epitopes, generally resulting from single amino acid substitutions which influence envelope conformation. Experiments on a double mutant showed that the combination of both mutations is not additive, suggesting that these variants utilized alternate pathways to elicit similar alterations of the HIV-1 envelope structure.

CD4-dependent, antibody-sensitive interactions between HIV-1 and its co-receptor CCR-5

The beta-chemokine receptor CCR-5 is an essential co-factor for fusion of HIV-1 strains of the non-syncytium-inducing (NSI) phenotype with CD4+ T-cells. The primary binding site for human immunodeficiency virus (HIV)-1 is the CD4 molecule, and the interaction is mediated by the viral surface glycoprotein gp120 (refs 6, 7). The mechanism of CCR-5 function during HIV-1 entry has not been defined, but we have shown previously that its beta-chemokine ligands prevent HIV-1 from fusing with the cell. We therefore investigated whether CCR-5 acts as a second binding site for HIV-1 simultaneously with or subsequent to the interaction between gp120 and CD4. We used a competition assay based on gp120 inhibition of the binding of the CCR-5 ligand, macrophage inflammatory protein (MIP)-1beta, to its receptor on activated CD4+ T cells or CCR-5-positive CD4- cells. We conclude that CD4 binding, although not absolutely necessary for the gp120-CCR-5 interaction, greatly increases its efficiency. Neutralizing monoclonal antibodies against several sites on gp120, including the V3 loop and CD4-induced epitopes, inhibited the interaction of gp120 with CCR-5, without affecting gp120-CD4 binding. Interference with HIV-1 binding to one or both of its receptors (CD4 and CCR-5) may be an important mechanism of virus neutralization.

An ex vivo method for studying inflammation in cynomolgus monkeys: analysis of interleukin-1 receptor antagonist

Nonhuman primates have been used as models for testing the role of interleukin-1 (IL-1) in inflammatory diseases, including endotoxemia. The objective of this investigation was to develop a reproducible and rapid method for in vivo evaluation of IL-1 antagonists using cynomolgus monkeys. IL-1 alone can induce many of the symptoms of endotoxemia in monkeys including fever, loss of appetite, and lethargy, however, test animals are slow to recover and may become desensitized to IL-1. We have developed an ex vivo method using whole blood for analysis of IL-1 antagonists administered in vivo to the monkeys and report here results for the naturally occurring IL-1 receptor antagonist, IL-1ra. In this procedure, animals are given an i.v. infusion of IL-1ra, and blood samples are taken preinfusion and during the infusion. The samples are incubated with or without IL-1 beta and the subsequent ex vivo induction of IL-6 determined. This allows analysis of the effects of in vivo pharmacodynamics on the efficacy of antagonists without exposing the test animals to IL-1. In this ex vivo protocol, each animal serves as its own control, eliminating from the assessment the large animal to animal variation observed with in vivo responses. By testing various doses, we estimate that 50% inhibition of IL-1 induced IL-6 can be achieved with an infusion of IL-1ra at 5 micrograms/kg/15 min. This method allows simple and efficient analysis of inhibitors and antagonists of IL-1 and, potentially, other effectors.

Architectural features and perceptions of community residences for people with mental retardation

Architects, group home administrators, people with mental retardation, family members of people with mental retardation, and college undergraduates substantially agreed regarding the rated homelikeness of slides of interiors of 20 community residences for people with mental retardation ranging from institutional to homey, mean r = .87. Clusters of physical features identified using an architectural inventory were found to be associated with homelikeness ratings. Adjectives applied to rooms with these features were determined using a Q-sort method. Two factors were identified from Q-sort correlations: Homelikeness-Institutionality and Spatial Organization as well as a third variable, privacy.