Adenosine triphosphate enhances osteoblast differentiation of rat dental pulp stem cells via the PLC-IP3 pathway and intracellular Ca 2+ signaling.

Intracellular Ca2+ signals are essential for stem cell function and play a significant role in the differentiation process. Dental pulp stem cells (DPSCs) are a potential source of stem cells; however, the mechanisms controlling cell differentiation remain largely unknown. Utilizing rat DPSCs, we examined the effect of adenosine triphosphate (ATP) on osteoblast differentiation and characterized its mechanism of action using real-time Ca 2+ imaging analysis. Our results revealed that ATP enhanced osteogenesis as indicated by Ca 2+ deposition in the extracellular matrix via Alizarin Red S staining. This was consistent with upregulation of osteoblast genes BMP2, Mmp13, Col3a1, Ctsk, Flt1, and Bgn. Stimulation of DPSCs with ATP (1-300 µM) increased intracellular Ca 2+ signals in a concentration-dependent manner, whereas histamine, acetylcholine, arginine vasopressin, carbachol, and stromal-cell-derived factor-1α failed to do so. Depletion of intracellular Ca 2+ stores in the endoplasmic reticulum by thapsigargin abolished the ATP responses which, nevertheless, remained detectable under extracellular Ca 2+ free condition. Furthermore, the phospholipase C (PLC) inhibitor U73122 and the inositol triphosphate (IP 3 ) receptor inhibitor 2-aminoethoxydiphenyl borate inhibited the Ca 2+ signals. Our findings provide a better understanding of how ATP controls osteogenesis in DPSCs, which involves a Ca 2+ -dependent mechanism via the PLC-IP 3 pathway. This knowledge could help improve osteogenic differentiation protocols for tissue regeneration of bone structures.

Progress towards rabies control and elimination in Vietnam.

Rabies is a fatal viral disease that causes an estimated 59,000 human deaths each year. The majority of these deaths occur in developing countries in Asia. Canine rabies is endemic to Vietnam, which is, however, moving towards the disease's elimination. Many countries, such as Vietnam, have invested tremendous resources in controlling rabies, highlighting the goal of regional and global elimination of this neglected disease. In Vietnam, rabies is recognised as one of five high-priority, zoonotic diseases by the Ministry of Health and the Ministry of Agriculture and Rural Development. Investment by the government and by international partners for rabies prevention and control has played a substantial role in reducing human rabies deaths from 404 cases in 1992 to 74 cases in 2017. The catalyst for this effort was the Prime Minister's creation of the National Rabies Program in 1996, which led to increased support and resources for rabies prevention and control. Interventions carried out since then include the expansion of post-exposure prophylaxis centres throughout the country, the introduction or revision of key legislation and guidelines, and improved multisectoral One Health collaboration. In addition, support from international partners, such as the World Organisation for Animal Health (OIE), the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO), and the Centers for Disease Control and Prevention (CDC), has helped to increase awareness, manage dog populations more effectively, and improve Vietnam's surveillance and diagnostic capabilities. To pursue the goal of eliminating dog-mediated rabies in Vietnam, political commitment is crucial. Resources must be made available to enforce the regulations and guidelines that will enable Vietnam to achieve greater canine rabies vaccination coverage. In this paper, the authors provide an overview of the animal and human health systems in Vietnam, as well as past, current and future directions of rabies prevention and control.

La rage est une maladie virale à l'issue mortelle faisant chaque année un nombre estimé de 59 000 victimes humaines. La plupart de ces décès surviennent dans les pays en développement d'Asie. Au Vietnam, la rage canine est endémique mais le pays poursuit activement l'objectif d'éliminer la rage de son territoire. À l'instar du Vietnam, plusieurs pays ont investi des ressources colossales pour contrôler la rage, renforçant ainsi la dimension régionale et mondiale de l'objectif d'élimination de cette maladie négligée. Au Vietnam, la rage figure parmi les cinq zoonoses hautement prioritaires prises en compte par le ministère de la Santé et le ministère de l'Agriculture et du développement rural. Les investissements consacrés à la prévention et au contrôle de la rage par le gouvernement et ses partenaires internationaux ont joué un rôle déterminant dans la réduction du nombre de décès humains dus à la rage, qui est passé de 404 cas en 1992 à 74 cas en 2017. L'élément catalyseur de cet effort a été la création en 1996 du Programme national de lutte contre la rage par le premier ministre de l'époque, ce qui a permis de renforcer les ressources et le soutien dédiés à la prévention et à la lutte contre la rage. Depuis lors, les interventions ont porté sur la création de centres de prophylaxie post-exposition sur tout le territoire, l'introduction ou la révision de la législation et des lignes directrices applicables et l'amélioration de la collaboration Une seule santé. En outre, le soutien de partenaires internationaux tels que l'Organisation mondiale de la santé animale (OIE), l'Organisation mondiale de la santé (OMS), l'Organisation des Nations Unies pour l'alimentation et l'agriculture (FAO) et les Centres pour le contrôle et la prévention des maladies (CDC, États-Unis d'Amérique) a abouti à une meilleure sensibilisation, à une gestion plus efficace des populations de chiens et à un renforcement des capacités de surveillance et de diagnostic au Vietnam. Un engagement politique fort est indispensable pour réussir à éliminer totalement la rage transmise par les chiens au Vietnam. Des ressources doivent être rendues disponibles afin de mettre en oeuvre la réglementation et les lignes directrices pertinentes et d'augmenter ainsi la couverture vaccinale de la population canine du pays. Les auteurs décrivent les systèmes de santé animale et publique du Vietnam ainsi que les orientations passées, actuelles et futures de la prévention et du contrôle de la rage dans le pays.

La rabia es una enfermedad vírica fatal, que según las estimaciones mata a 59 000 personas al año, mayoritariamente en países en desarrollo asiáticos. La rabia canina es endémica en el Vietnam, país que no obstante avanza ahora hacia la eliminación de la enfermedad. Como el Vietnam, muchos países han invertido cantidades colosales de recursos en la lucha antirrábica, subrayando con ello su compromiso con el objetivo de eliminar esta enfermedad desatendida a escala regional y mundial. El Ministerio de Salud y el Ministerio de Agricultura y Desarrollo Rural del Vietnam tienen catalogada la rabia como una de las cinco enfermedades zoonóticas que revisten máxima prioridad. Las inversiones en prevención y control de la rabia realizadas por el gobierno y por asociados internacionales han ayudado sensiblemente a reducir el número de personas muertas por la rabia, que ha pasado de 404 casos en 1992 a 74 en 2017. El catalizador de este esfuerzo fue la creación en 1996, por iniciativa del Primer Ministro, del Programa Nacional contra la Rabia, que se tradujo en un aumento del apoyo y los recursos destinados a prevenir y combatir la enfermedad. Entre otras intervenciones, desde entonces se ha multiplicado en todo el país el número de centros donde se dispensa profilaxis tras la exposición, se han promulgado o revisado leyes, decretos y directrices fundamentales y se ha mejorado la colaboración multisectorial en clave de Una sola salud. Además, el respaldo de asociados internacionales como la Organización Mundial de Sanidad Animal (OIE), la Organización Mundial de la Salud (OMS), la Organización de las Naciones Unidas para la Alimentación y la Agricultura (FAO) o los Centros para el Control y la Prevención de Enfermedades (CDC) de los Estados Unidos ha ayudado a generar una mayor conciencia del problema, a gestionar más eficazmente las poblaciones de perros y a dotar al país de mejores medios de vigilancia y diagnóstico. Para hacer realidad el objetivo de eliminar del Vietnam la rabia transmitida por perros, la voluntad política es un factor clave, pues hay que poner sobre la mesa los recursos necesarios para aplicar los reglamentos y normas que permitirán al país ampliar la cobertura de vacunación canina antirrábica. Tras trazar una panorámica de los sistemas sanitario y zoosanitario del Vietnam, los autores describen el rumbo pasado, presente y futuro de las labores de prevención y control de la rabia en el país.

Emergence of New Delhi metallo-beta-lactamase 1 and other carbapenemase-producing Acinetobacter calcoaceticus-baumannii complex among patients in hospitals in Ha Noi, Viet Nam.

Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in Hanoi, Vietnam. We identified 23/582 isolates (4 %) (11 from hospital A, five from hospital B, and seven from hospital C) that were NDM-1 positive, and among them 18 carried additional carbapenemase genes, including seven isolates carrying NDM-1, IMP-1, and OXA-58 with high MICs for carbapenems. Genotyping indicated that NDM-1 carrying A. baumannii have expanded clonally in these hospitals. Five new STs (ST1135, ST1136, ST1137, ST1138, and ST1139) were identified. One isolate carried NDM-1 on a plasmid belonging to the N-repA replicon type; no NDM-1-positive plasmids were identified in the other isolates. We have shown the extent of the carbapenem resistance and the local clonal spread of A. baumannii carrying NDM-1 in these hospitals; coexistence of NDM-1 and IMP-1 is reported for the first time from Vietnam here, and this will further seriously limit future therapeutic options.

Clinical and epidemiological characteristics of acute respiratory virus infections in Vietnamese children.

Information about viral acute respiratory infections (ARIs) is essential for prevention, diagnosis and treatment, but it is limited in tropical developing countries. This study described the clinical and epidemiological characteristics of ARIs in children hospitalized in Vietnam. Nasopharyngeal samples were collected from children with ARIs at Ho Chi Minh City Children's Hospital 2 between April 2010 and May 2011 in order to detect respiratory viruses by polymerase chain reaction. Viruses were found in 64% of 1082 patients, with 12% being co-infections. The leading detected viruses were human rhinovirus (HRV; 30%), respiratory syncytial virus (RSV; 23·8%), and human bocavirus (HBoV; 7·2%). HRV was detected all year round, while RSV epidemics occurred mainly in the rainy season. Influenza A (FluA) was found in both seasons. The other viruses were predominant in the dry season. HRV was identified in children of all age groups. RSV, parainfluenza virus (PIV) 1, PIV3 and HBoV, and FluA were detected predominantly in children aged 24 months, respectively. Significant associations were found between PIV1 with croup (P < 0·005) and RSV with bronchiolitis (P < 0·005). HBoV and HRV were associated with hypoxia (P < 0·05) and RSV with retraction (P < 0·05). HRV, RSV, and HBoV were detected most frequently and they may increase the severity of ARIs in children.

Human rhinovirus infections in hospitalized children: clinical, epidemiological and virological features.

Molecular epidemiology and clinical impact of human rhinovirus (HRV) are not well documented in tropical regions. This study compared the clinical characteristics of HRV to other common viral infections and investigated the molecular epidemiology of HRV in hospitalized children with acute respiratory infections (ARIs) in Vietnam. From April 2010 to May 2011, 1082 nasopharyngeal swabs were screened for respiratory viruses by PCR. VP4/VP2 sequences of HRV were further characterized. HRV was the most commonly detected virus (30%), in which 70% were diagnosed as either pneumonia or bronchiolitis. Children with single HRV infections presented with significantly higher rate of hypoxia than those infected with respiratory syncytial virus or parainfluenza virus (PIV)-3 (12·4% vs. 3·8% and 0%, respectively, P < 0·05), higher rate of chest retraction than PIV-1 (57·3% vs. 34·5%, P = 0·028), higher rate of wheezing than influenza A (63·2% vs. 42·3%, P = 0·038). HRV-C did not differ to HRV-A clinically. The genetic diversity and changes of types over time were observed and may explain the year-round circulation of HRV. One novel HRV-A type was discovered which circulated locally for several years. In conclusion, HRV showed high genetic diversity and was associated with significant morbidity and severe ARIs in hospitalized children.

Immune responses against norovirus GII.4 virus-like particles in mice.

Norovirus (NoV) is a causative agent of gastroenteritis in children and adults worldwide. To evaluate the safety and effectiveness of a NoV vaccine candidate, 100 µg of GII.4 NoV-like particles (VLPs) was challenged orally (oral and intrabuccal administration) and by subcutaneous injection without adjuvant in mice. The subcutaneous injection induced IgG in sera, but not IgA in feces. The oral delivery method induced IgA in both sera and feces, but not IgG in sera. However, challenging by the intrabuccal administration induced IgG in sera and IgA in both sera and feces, especially by 2-dose immunization. The peak of specific immune responses by the intrabuccal administration was detected later than that of the oral delivery method. Heterologous immune responses against other genotypes were also recognized. NoV-specific IFN-γ was detected after the intrabuccal administration. These findings indicated that the administration of NoV VLPs by intrabuccal administration could induce the best immune responses against NoV in mice.

Common isolation of New Delhi metallo-beta-lactamase 1-producing Enterobacteriaceae in a large surgical hospital in Vietnam.

This study sought to monitor the presence of carbapenem-resistant Enterobacteriaceae (CRE) and the proportion New Delhi metallo-beta-lactamase 1 (NDM-1)-producing bacteria between August 2010 and December 2012 in a surgical hospital in Vietnam. We identified 47 CRE strains from a total of 4,096 Enterobacteriaceae isolates (1.1 %) that were NDM-1-positive from 45 patients admitted to 11 different departments, with the majority being from the urology department. The NDM-1 gene was found in seven different species. Genotyping revealed limited clonality of NDM-1-positive isolates. Most of the isolates carried the NDM-1 gene on a plasmid and 17.8 % (8/45) of those were readily transferable. We found five patients at admission and one patient at discharge with NDM-1-positive bacteria in their stool. From 200 screening environmental hospital samples, five were confirmed to be NDM-1-positive and included Acinetobacter species (n = 3) and Enterobacter aerogenes (n = 2). The results reveal that NDM-1-producing Enterobacteriaceae are commonly isolated in patients admitted to a Vietnamese surgical hospital and are also detected in the hospital environment.

Economic outcomes among microfinance group members receiving community-based chronic disease care: Cluster randomized trial evidence from Kenya.

BACKGROUND: Poverty can be a robust barrier to HIV care engagement. We assessed the extent to which delivering care for HIV, diabetes and hypertension within community-based microfinance groups increased savings and reduced loan defaults among microfinance members living with HIV. METHODS: We analyzed cluster randomized trial data ascertained during November 2020-May 2023 from 57 self-formed microfinance groups in western Kenya. Groups were randomized 1:1 to receive care for HIV and non-communicable diseases in the community during regular microfinance meetings (intervention) or at a health facility during routine appointments (standard care). Community and facility care provided clinical evaluations, medications, and point-of-care testing. The trial enrolled 900 microfinance members, with data collected quarterly for 18-months. We used a two-part model to estimate intervention effects on microfinance shares purchased, and a negative binomial regression model to estimate differences in loan default rates between trial arms. We estimated effects overall and by participant characteristics. RESULTS: Participants' median age and distance from a health facility was 52 years and 5.6 km, respectively, and 50% reported earning less than $50 per month. The probability of saving any amount (>$0) through purchasing microfinance shares was 2.7 percentage points higher among microfinance group members receiving community vs. facility care. Community care recipients and facility care patients saved $44.90 and $25.24 over 18-months, respectively, and the additional amount saved by community care recipients was statistically significant (p = 0.036). Overall and in stratified analyses, loan defaults rates were not statistically significantly different between community and facility care patients. CONCLUSIONS: Receiving integrated care in the community was significantly associated with modest increases in savings. We did not find any significant association between community-delivered care and reductions in loan defaults among HIV-positive microfinance group members. Longer follow up examination and formal mediation analyses are warranted.

Initial phase establishment of an in vitro method for developmental neurotoxicity test using Ki-67 in human neural progenitor cells.

Building a precise alternative neurotoxicological test is of great importance to respond to societal and ethical requirements. In this study, a new developmental neurotoxicity test (DNT) was established with the human neural progenitor cell line. ReNcell CX cells were exposed to neurotoxic chemicals (aphidicolin, hydroxyurea, cytosine arabinoside, 5-fluorouracil, and ochratoxin A) or non-neurotoxic chemicals (sodium gluconate, sodium bicarbonate, penicillin G, and saccharin). Propidium iodide (PI) was used to evaluate cell viability. BrdU and Ki-76 were employed to determine cell proliferation. Based on the cell viability and proliferation, mathematical models were built by linear discriminant analysis. Furthermore, the neurotoxic-considered chemicals inhibited cell cycle progression at the protein level, supporting the biomolecular rationale for the predictive model. Overall, these results show that the new test method can be used to determine the potential developmental neurotoxicants or new drug candidates.

Cigarette smoke extraxt influences intracellular calcium concentration in A549 cells.

Cigarette smoking is a major risk factor for pulmonary diseases, including chronic obstructive pulmonary disease (COPD) and cancer. Cigarette smoke is reported to contain over 4,000 chemical compounds. Therefore, it needs to study the effects of cigarette smoke extract (CSE) administration on intracellular calcium concentration. In this study, we investigated how CSE influences intracellular calcium concentration in human lung adenocarcinoma A549 cells. The CSE concentrations used (0.4, 2, 3%) did not influence cell viability. However, at these CSE concentrations, calcium influx transient receptor potential vanilloid 4 (TRPV4) and transient receptor potential vanilloid 6 (TRPV6) proteins significantly increased, whereas calcium efflux sodium-calcium exchanger (NCX1) and plasma membrane Ca2+ ATPase (PMCA1) proteins significantly decreased from those of the control cells. The 3% CSE treatment produced an intracellular calcium concentration higher than that of the control treatment through methods of co-transfection of pGP-CMV-GCaMP6f/CMV-R-GECO1.2 and Rhod-4 Assay. CSE induced concentration-dependent increments in hypoxia-inducible factor (HIF)-1α and HIF-2α protein levels. Moreover, phosphorylation of ERK and Akt was induced by CSE treatment. Also, mitochondrial marker B-cell lymphoma 2 (Bcl-2) protein level decreased and Bcl-2-associated X (Bax) protein level increased following CSE treatment. Also, endoplasmic reticulum (ER) stress markers BiP, CHOP, p-SAPK, and p-eIF2α levels were increased by CSE treatment. These results suggest that CSE may increase the concentration of intracellular calcium, thus increasing mitochondrial and ER stress.

Potassium-dependent sodium/calcium exchanger 3 (Nckx3) depletion leads to abnormal motor function and social behavior in mice.

Transcellular calcium transport is an essential activity in mineralized tissue formation, including that in nervous systems. Dysregulation of Ca2+ homeostasis can induce excitotoxicity and neurodegeneration in the central nervous system. Nckx3, a potassium-dependent Na+/Ca2+ exchanger, is most abundant in the brain and has a critical role in the transport of intracellular calcium across the cell membrane. However, the roles of Nckx3 in neuron development and function remain unreported. Herein, we examined the behaviors of Nckx3-knock-out mice at the age of six weeks. Detailed behavioral analyses showed Nckx3-/- mice exhibited an increase in moving distances in the open field test. Additionally, the rotarod test revealed motor learning defects in Nckx3-/- mice. Both Nckx3+/- and Nckx-/- mice also exhibited deficits in sociability and social novelty preference. Furthermore, Nckx-/- mice displayed increased depression-related behavior. However, there was no significant change in cognition function detected in Nckx-/- mice. This study demonstrates that NCKX3 is involved in behavior and neuronal function.

Applying the transtheoretical model to cervical cancer screening in Vietnamese-American women.

BACKGROUND: Low levels of Papanicolaou (Pap) screening participation in Vietnamese-American women remain a significant public health problem. The transtheoretical model (TTM) suggests that individuals adopting Pap smear behaviour move through a series of stages of readiness to change. Determining a woman's level of readiness for regular Pap testing and identifying the screening behaviour that an individual already performs is important in the development of successful intervention programmes that address the specific needs of Vietnamese-American women in different stages. AIMS: To describe Pap smear screening behaviours of Vietnamese-American women, and to examine whether constructs (stages of change, self-efficacy and perceived benefits/barriers) from the TTM are applicable to Vietnamese-American women relative to Pap testing. METHODS: A descriptive, cross-sectional design with snowball sampling was used to recruit participants. A total of 80 Vietnamese-American women completed the self-administered questionnaire. RESULTS: Most respondents (62.5%) reported previous Pap testing and only 46.3% receiving regular Pap testing. Compared with those in the pre-contemplation stage of the TTM, participants in maintenance reported significantly less self-efficacy (F (3, 73) = 4.85, P = 0.00), a lower level of perceived barriers (F (3, 75) = 5.99, P = 0.00) and a higher level of perceived benefits (F (3, 76) = 3.91, P = 0.01) relative to Pap smear. CONCLUSIONS: The results support some of the assumptions of the TTM but raise questions about the predicted relationships between stages of change and self-efficacy. Continued research is needed to identify the most effective theory-based interventions for evidence-based nursing practice in this population.

Arginine vasopressin inhibits adipogenesis in human adipose-derived stem cells.

Intracellular Ca(2+) signaling is important for stem cell differentiation and there is evidence it may coordinate the process. Arginine vasopressin (AVP) is a neuropeptide hormone secreted mostly from the posterior pituitary gland and increases Ca(2+) signals mainly via V1 receptors. However, the role of AVP in adipogenesis of human adipose-derived stem cells (hASCs) is unknown. In this study, we identified the V1a receptor gene in hASCs and demonstrated that AVP stimulation increased intracellular Ca(2+) concentration during adipogenesis. This effect was mediated via V1a receptors, Gq-proteins and the PLC-IP3 pathway. These Ca(2+) signals were due to endoplasmic reticulum release and influx from the extracellular space. Furthermore, AVP supplementation to the adipogenic medium decreased the number of adipocytes and adipocyte marker genes during differentiation. The effect of AVP on adipocyte formation was reversed by the V1a receptor blocker V2255. These findings suggested that AVP may function to inhibit adipocyte differentiation.

Irisin Controls Growth, Intracellular Ca2+ Signals, and Mitochondrial Thermogenesis in Cardiomyoblasts.

Exercise offers short-term and long-term health benefits, including an increased metabolic rate and energy expenditure in myocardium. The newly-discovered exercise-induced myokine, irisin, stimulates conversion of white into brown adipocytes as well as increased mitochondrial biogenesis and energy expenditure. Remarkably, irisin is highly expressed in myocardium, but its physiological effects in the heart are unknown. The objective of this work is to investigate irisin's potential multifaceted effects on cardiomyoblasts and myocardium. For this purpose, H9C2 cells were treated with recombinant irisin produced in yeast cells (r-irisin) and in HEK293 cells (hr-irisin) for examining its effects on cell proliferation by MTT [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and on gene transcription profiles by qRT-PCR. R-irisin and hr-irisin both inhibited cell proliferation and activated genes related to cardiomyocyte metabolic function and differentiation, including myocardin, follistatin, smooth muscle actin, and nuclear respiratory factor-1. Signal transduction pathways affected by r-irisin in H9C2 cells and C57BL/6 mice were examined by detecting phosphorylation of PI3K-AKT, p38, ERK or STAT3. We also measured intracellular Ca2+ signaling and mitochondrial thermogenesis and energy expenditure in r-irisin-treated H9C2 cells. The results showed that r-irisin, in a certain concentration rage, could activate PI3K-AKT and intracellular Ca2+ signaling and increase cellular oxygen consumption in H9C2 cells. Our study also suggests the existence of irisin-specific receptor on the membrane of H9C2 cells. In conclusion, irisin in a certain concentration rage increased myocardial cell metabolism, inhibited cell proliferation and promoted cell differentiation. These effects might be mediated through PI3K-AKT and Ca2+ signaling, which are known to activate expression of exercise-related genes such as follistatin and myocardin. This work supports the value of exercise, which promotes irisin release.

Involvement of angiotensin receptor subtypes in osmotically induced release of vasopressin.

We have previously shown that AT1 and AT2 angiotensin II (Ang II) receptors mediate the release of arginine vasopressin (AVP) to central injections of Ang II. In this study we have tested the hypothesis that Ang II, acting at AT1 and AT2 receptors in the brain, is involved in mediating osmotically stimulated AVP release. Adult Sprague-Dawley rats were fitted with intraventricular (i.v.t.) cannulas and catheters in the carotid artery and the femoral vein. Intraventricular injections of Ang II receptor antagonists specific to different subtypes of the receptor (AT1 and AT2) were given before a 30 min infusion of hypertonic (2.5 M) saline. Arterial blood samples were collected 5 min before and at two time points after (+15 min and +30 min) beginning the saline infusion. We found that both losartan (AT1 specific) and CGP42112A (AT2 specific) significantly reduced osmotically induced release of AVP. PD123319 (AT2 specific) had no effect of osmotically stimulated AVP release. A combined treatment of losartan + PD123319 was no more effective than losartan in blocking the AVP response. Since losartan was the most rapid and effective antagonist of osmotically stimulated AVP release, we conclude that AT1 receptors are directly involved in the response. However, but since CGP42112A was also an effective antagonist and since, AT2 receptors are located at sites distant from the hypothalamus, such as the locus ceruleus, they may also contribute to this response. We conclude that brain Ang II receptors are involved in osmotically stimulated AVP release.

Mapping the determinants of the CCR5 amino-terminal sulfopeptide interaction with soluble human immunodeficiency virus type 1 gp120-CD4 complexes.

CD4 and CCR5 mediate fusion and entry of R5 human immunodeficiency virus type 1 (HIV-1) strains. Sulfotyrosine and other negatively charged residues in the CCR5 amino-terminal domain (Nt) are crucial for gp120 binding and viral entry. We previously showed that a soluble gp120-CD4 complex specifically binds to a peptide corresponding to CCR5 Nt residues 2 to 18, with sulfotyrosines in positions 10 and 14. This sulfopeptide also inhibits soluble gp120-CD4 binding to cell surface CCR5 as well as infection by an R5 virus. Here we show that residues 10 to 18 constitute the minimal domain of the CCR5 Nt that is able to specifically interact with soluble gp120-CD4 complexes. In addition to sulfotyrosines in positions 10 and 14, negatively charged residues in positions 11 and 18 participate in this interaction. Furthermore, the CCR5 Nt binds to a CD4-induced surface on gp120 that is composed of conserved residues in the V3 loop stem and the C4 domain. Binding of gp120 to cell surface CCR5 is further influenced by residues in the crown of the V3 loop, C1, C2, and C3. Our data suggest that gp120 docking to CCR5 is a multistep process involving several independent regions of the envelope glycoprotein and the coreceptor.

Single-dose safety, pharmacology, and antiviral activity of the human immunodeficiency virus (HIV) type 1 entry inhibitor PRO 542 in HIV-infected adults.

PRO 542 (CD4-IgG2) is a recombinant antibody-like fusion protein wherein the Fv portions of both the heavy and light chains of human IgG2 have been replaced with the D1D2 domains of human CD4. Unlike monovalent and divalent CD4-based proteins, tetravalent PRO 542 potently neutralizes diverse primary human immunodeficiency virus (HIV) type 1 isolates. In this phase 1 study, the first evaluation of this compound in humans, HIV-infected adults were treated with a single intravenous infusion of PRO 542 at doses of 0.2-10 mg/kg. PRO 542 was well tolerated, and no dose-limiting toxicities were identified. Area under the concentration-time curve, and peak serum concentrations increased linearly with dose, and a terminal serum half-life of 3-4 days was observed. No patient developed antibodies to PRO 542. Preliminary evidence of antiviral activity was observed as reductions in both plasma HIV RNA and plasma viremia. Sustained antiviral effects may be achieved with repeat dosing with PRO 542.

Differential inhibition of human immunodeficiency virus type 1 fusion, gp120 binding, and CC-chemokine activity by monoclonal antibodies to CCR5.

The CC-chemokine receptor CCR5 mediates fusion and entry of the most commonly transmitted human immunodeficiency virus type 1 (HIV-1) strains. We have isolated six new anti-CCR5 murine monoclonal antibodies (MAbs), designated PA8, PA9, PA10, PA11, PA12, and PA14. A panel of CCR5 alanine point mutants was used to map the epitopes of these MAbs and the previously described MAb 2D7 to specific amino acid residues in the N terminus and/or second extracellular loop regions of CCR5. This structural information was correlated with the MAbs' abilities to inhibit (i) HIV-1 entry, (ii) HIV-1 envelope glycoprotein-mediated membrane fusion, (iii) gp120 binding to CCR5, and (iv) CC-chemokine activity. Surprisingly, there was no correlation between the ability of a MAb to inhibit HIV-1 fusion-entry and its ability to inhibit either the binding of a gp120-soluble CD4 complex to CCR5 or CC-chemokine activity. MAbs PA9 to PA12, whose epitopes include residues in the CCR5 N terminus, strongly inhibited gp120 binding but only moderately inhibited HIV-1 fusion and entry and had no effect on RANTES-induced calcium mobilization. MAbs PA14 and 2D7, the most potent inhibitors of HIV-1 entry and fusion, were less effective at inhibiting gp120 binding and were variably potent at inhibiting RANTES-induced signaling. With respect to inhibiting HIV-1 entry and fusion, PA12 but not PA14 was potently synergistic when used in combination with 2D7, RANTES, and CD4-immunoglobulin G2, which inhibits HIV-1 attachment. The data support a model wherein HIV-1 entry occurs in three stages: receptor (CD4) binding, coreceptor (CCR5) binding, and coreceptor-mediated membrane fusion. The antibodies described will be useful for further dissecting these events.