PubMed Health⌕ Search

Biomedical subjects

Daniel Malamud

Publications and source records attributed to Daniel Malamud.

17 recordsLinked to original sources
PubMed2006

The N-terminal SRCR-SID domain of gp-340 interacts with HIV type 1 gp120 sequences and inhibits viral infection.

Proteins encoded by the SRCR superfamily including gp340 recognize repeated patterns on pathogenic microorganisms and play important roles in innate immune defense as well as epithelial cell differentiation. Based upon the presence of SRCR domains in proteins with broad binding specificities and high amino acid sequence homology, it was speculated that SRCR domains may be involved in ligand binding. In this study, a truncated gp340 molecule representing the N-terminal sequence including the first SRCR and one-half of the first SID was expressed in mammalian 293 cells as a 35-kDa recombinant protein. The expressed protein was recognized by a panel of antibodies specific for human salivary agglutinin (SAG) and the full-length parental gp340 and exhibited biological properties similar to the entire 340-kDa glycoprotein. The truncated gp340 protein bound to the same HIV-1 V3 sequences previously identified to interact with full-length SAG in a Ca2+ -dependent manner. The recombinant N-terminal SRCR protein also demonstrated potent anti-HIV- 1 activity against both CCR5- and CXCR4-using isolates, similar to the full-length glycoprotein. We have, thus, demonstrated that the N-terminal SRCR of gp340 directly interacts with viral gp120 and likely mediates anti-HIV-1 activity via this interaction.

Anti-HIV Agents↗
PubMed2006

Mucosal innate immune factors in the female genital tract are associated with vaginal HIV-1 shedding independent of plasma viral load.

Recent studies indicate that mucosal innate immune factors modulate HIV-1 infection in vitro. Our interest was to examine the levels of innate mucosal factors for their potential association with HIV-1 shedding in the female genital tract. Vaginal lavages were collected from HIV-1-infected women who had vaginal viral loads (VVL) that were below, within, or above the 90% confidence interval (CI) predicted by their matched plasma viral loads. Innate immune factors [cathepsin D, lactoferrin (Lf), myeloid related protein (MRP)-8, MRP-8/14, secretory leukocyte protease inhibitor, and gp340], cytokines (IL-1beta and TNF-alpha), and chemokines (MIP-1alpha, MIP-1beta, RANTES, and SDF-1alpha) were quantified by ELISA. Leukocyte levels were determined using a leukocyte reagent strip for urinalysis. Lf, MRP-8/14, gp340, and IL-1beta levels were significantly higher in vaginal lavages above the 90% CI and generally correlated with each other and with VVL. Leukocyte levels were significantly higher in the lavages that had virus shedding above the 90% CI and correlated strongly with Lf levels and VVL. In this group of women, these results suggest that the levels of certain innate immune factors are more closely associated with HIV-1 shedding in the genital mucosa than plasma virus concentrations.

Adolescent↗
PubMed2006

Oral-based techniques for the diagnosis of infectious diseases.

Saliva and other types of oral samples can readily be used for noninvasive diagnosis of diseases of the oral cavity and systemic diseases. Following an introduction outlining the types of oral samples and the analytes that can be measured in these samples, a detailed description of a novel oral-based diagnostic system to detect multiple bacterial and/or viral pathogens is presented. A reasonably priced, portable, point-of-care diagnostic system should be available within five years.

Communicable Diseases↗
PubMed2005

Oral diagnostics for the geriatric populations: current status and future prospects.

Because it is a noninvasive technique, there is growing interest in replacing blood with oral-based methods of diagnostics. Oral diagnostics may be used for diagnosis and therapeutic drug monitoring of both oral diseases (eg, caries, periodontal disease,oral lesions, oral cancer) and systemic diseases (eg, infectious diseases, including HIV and AIDS, autoimmune diseases, cancer,and endocrine disorders). The authors address both existing techniques and oral-based diagnostics that will be applicable to the aging population in the future. They also highlight those techniques that are uniquely suited to point-of-care applications.

Aged↗
PubMed2005

Distribution of a 3.5-mL (1.0%) C31G vaginal gel using magnetic resonance imaging.

C31G (Savvy) has been developed as a topical vaginal microbicide with broad-spectrum antibacterial and antiviral properties. The objective of this study was to evaluate the distribution of a 1.0% concentration of (3.5 mL) C31G vaginal gel in the human pelvis using magnetic resonance imaging (MRI). Gel delivery with a standard applicator was primarily to the upper vagina and was well tolerated. Vaginal mucosal coverage at 18 min was excellent with 92% linear coverage and 75% surface contact coverage of the vagina. The upper vagina was almost completely covered and gel was also noted in the lower vagina. Coverage 6 h after application was substantially decreased, with 60% of maximal linear coverage and 41% surface contact. There was a very minimal coverage of the vaginal mucosa noted 24 h following insertion. Simulated intercourse resulted in relatively little change in overall distribution at all three time points. Repeat application of the gel may be necessary if intercourse has not occurred within the first few hours after initial insertion.

Administration, Intravaginal↗
PubMed2005

Comparative safety evaluation of the candidate vaginal microbicide C31G.

C31G is currently the focus of clinical trials designed to evaluate this agent as a microbicidal and spermicidal agent. In the following studies, the in vivo safety of C31G was assessed with a Swiss Webster mouse model of cervicovaginal toxicity and correlated with results from in vitro cytotoxicity experiments and published clinical observations. A single exposure of unformulated 1% C31G resulted in mild-to-moderate epithelial disruption and inflammation at 2 and 4 h postapplication. The columnar epithelium of the cervix was the primary site of damage, while no perturbation of the vaginal mucosa was observed. In contrast, application of unformulated 1.7% C31G resulted in greater levels of inflammation in the cervical epithelium at 2 h postapplication and severe epithelial disruption that persisted to 8 h postapplication. Application of a nonionic aqueous gel formulation containing 1% C31G resulted in no apparent cervicovaginal toxicity at any time point evaluated. However, formulation of 1.7% C31G did not substantially reduce the toxicity associated with unformulated C31G at that concentration. These observations correlate with findings gathered during a recent clinical trial, in which once-daily applications resulted in no adverse events in women receiving the formulation containing 1% C31G, compared to moderate-to-severe adverse events in 30% of women receiving the 1.7% C31G formulation. The Swiss Webster mouse model was able to effectively discriminate between concentrations and formulations of C31G that produced distinct clinical effects in human trials. The Swiss Webster animal model may be a highly valuable tool for preclinical evaluation of candidate vaginal microbicides.

Administration, Intravaginal↗
PubMed2004

Thermosiphon-based PCR reactor: experiment and modeling.

A self-actuated, flow-cycling polymerase chain reaction (PCR) reactor that takes advantage of buoyancy forces to continuously circulate reagents in a closed loop through various thermal zones has been constructed, tested, and modeled. The heating required for the PCR is advantageously used to induce fluid motion without the need for a pump. Flow velocities on the order of millimeters per second are readily attainable. In our preliminary prototype, we measured a cross-sectionally averaged velocity of 2.5 mm/s and a cycle time of 104 s. The flow velocity is nearly independent of the loop's length, making the device readily scalable. Successful amplifications of 700- and 305-bp fragments of Bacillus cereus genomic DNA have been demonstrated. Since the device does not require any moving parts, it is particularly suitable for miniature systems.

Bacillus cereus↗
PubMed2004

In vitro test to evaluate the interaction between synthetic cervical mucus and vaginal formulations.

The interaction and mixing between a bilayer sample of mucus and vaginal formulation was evaluated through viscosity measurements with respect to time and shear. Physical mixtures of mucus and vaginal formulation were used as controls. Three test protocols were designed: (1) constant shear, (2) intermittent shear, and (3) delayed shear. Several marketed vaginal products (Gynol II, KY Plus, KY, and Advantage-S) and experimental formulations (C31G with hydroxyethylcellulose [HEC]) were evaluated and compared by these tests. The results of the constant shear test showed that the shear stress profile of the bilayer approached that of the corresponding physical mixture, consistent with complete mixing of the bilayer under shear. The time taken for the bilayer to mix completely was in the following order: KY Plus > Gynol II and C31G > KY > Advantage-S. Under the intermittent shear protocol, the following order for complete mixing was observed: KY Plus > C31G > Gynol II > KY > Advantage-S. The 2 products evaluated by the delayed shear test, C31G and Gynol II, were both completely mixed at 180 minutes. The development of an in vitro test, when coupled with in vivo data, should serve in the screening and evaluation of future vaginal formulations.

Administration, Intravaginal↗
PubMed2004

In vivo distribution of a vaginal gel: MRI evaluation of the effects of gel volume, time and simulated intercourse.

A microbicide is designed to coat the vaginal epithelium and prevent transmission of HIV. Complete coverage is desired for optimal protection. In vivo factors affecting coverage have not yet been studied. This randomized crossover trial evaluates the effect of gel volume and patient activity upon vaginal epithelial coating. Gynol II gel was mixed with a magnetic resonance imaging (MRI) contrast agent. Ten women self-inserted, on separate visits, 3 or 5 mL of gel and underwent serial MRI scanning both before and after simulated intercourse. Gel spread was dependent upon time and volume. There was modest spread during the first hour and greater spread 6 h after insertion. Five milliliters of gel resulted in statistically significantly greater coverage immediately following insertion, within the first 30 min and at 6 h after insertion. Simulated intercourse greatly enhances gel spread. After simulated intercourse, the distribution of the gel at each volume was similar. Less leakage of gel was reported with the smaller volume.

Adult↗
PubMed2004

gp340 (SAG) binds to the V3 sequence of gp120 important for chemokine receptor interaction.

Human saliva contains multiple components that inhibit HIV-1 infection in vitro, which may contribute to low oral HIV-1 transmission. Salivary agglutinin (SAG) is a high-molecular-weight glycoprotein encoded by DMBT-1 and identical to gp340, a member of the lung scavange receptor, cysteine-rich receptor family. gp340 binds to surfactants A and D, which is believed to function in the clearance of microorganisms from the lung, as part of the innate immune response. Previously we reported that SAG (gp340) specifically inhibits HIV-1 infection with broad activity against diverse HIV-1 isolates. This gp340 inhibitory activity is mediated by binding to viral gp120 and involves a region different from the CD4-binding site on gp120. Here, we report that the gp340-binding region is localized to a linear, highly conserved sequence near the stem of the V3 loop that is critical for chemokine receptor interaction during viral binding and infection. The interaction of gp340 with gp120 is enhanced by prebinding of sCD4 to gp120, suggesting that gp340 inhibitory activity is mediated by blocking access of the gp120 to the chemokine receptor.

Agglutinins↗
PubMed2004

Comparison of oral fluid collectors for use in a rapid point-of-care diagnostic device.

Orally based diagnostic testing is emerging as an alternative, noninvasive method for analyzing a variety of analytes. These analytes include pathogens, antibodies, drugs, and nucleic acids. In the present study we developed a protocol for evaluation of collectors that could be used in orally based, point-of-care diagnostics. A performance comparison was carried out with a number of commercially available collectors, and their ability to deliver fluid, proteins, bacteria, and nucleic acid from pathogens compatible with PCR was assessed. The collectors were all capable of picking up and delivering test materials, albeit at various levels.

Diagnostic Techniques and Procedures↗
PubMed2003

Salivary agglutinin inhibits HIV type 1 infectivity through interaction with viral glycoprotein 120.

Salivary agglutinin (SAG) is a high molecular mass glycoprotein (340 kDa) that plays important roles in innate immunity. SAG has been found to specifically inhibit HIV-1 infectivity and to bind to virus through the envelope protein gp120. Although SAG binds to gp120 of the virus, the exact nature of this binding has not been characterized. Using surface plasmon resonance technology, we have found that SAG interacts with recombinant envelopes derived from diverse HIV-1 isolates with K(D) values ranging from 10(-7) to 10(-10) M, comparable to gp120-sCD4 binding. Furthermore, SAG binding to gp120 is Ca(2+) dependent. sCD4 prebound to gp120 failed to abrogate SAG binding, suggesting a distinct mechanism for SAG inhibition of HIV-1 infectivity. Inhibition by monoclonal antibodies specific for carbohydrates also implicates the involvement of carbohydrates in the interaction between SAG and gp120. These results argue that the anti-HIV-1 activity of SAG is due to carbohydrate-mediated binding to gp120. A demonstration that SAG is related to lung scavenger receptor, gp-340, further suggests the roles of SAG in preventing pathogen invasion at the entry portal and raises its potential as an anti-HIV-1 drug candidate.

Agglutinins↗
PubMed2002

Synthetic cervical mucus formulation.

A synthetic formulation has been developed with viscosity, spinnbarkeit, and pH comparable to that reported for human cervical mucus. The formulation contains guar gum crosslinked with borate ion, mucin (dried porcine gastric), and a mixed preservative system in pH 7.4, 0.1M phosphate buffer. The guar gum source, mucin concentration, and method of preparation were shown to be critical factors in the performance of the formulation.

Borates↗
PubMed2002

Comparative in vitro sensitivities of human immune cell lines, vaginal and cervical epithelial cell lines, and primary cells to candidate microbicides nonoxynol 9, C31G, and sodium dodecyl sulfate.

In experiments to assess the in vitro impact of the candidate microbicides nonoxynol 9 (N-9), C31G, and sodium dodecyl sulfate (SDS) on human immune and epithelial cell viability, cell lines and primary cell populations of lymphocytic and monocytic origin were generally shown to be equally sensitive to exposures ranging from 10 min to 48 h. However, U-937 cells were more sensitive to N-9 and C31G after 48 h than were primary monocyte-derived macrophages. Cytokine activation of monocytes and lymphocytes had no effect on cell viability following exposure to these microbicidal compounds. Primary and passaged vaginal epithelial cultures and cell lines differed in sensitivity to N-9 and C31G but not SDS. These studies provide a foundation for in vitro experiments in which cell lines of human immune and epithelial origin can be used as suitable surrogates for primary cells to further investigate the effects of microbicides on cell metabolism, membrane composition, and integrity and the effects of cell type, proliferation, and differentiation on microbicide sensitivity.

Betaine↗