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Biomedical subjects

D M Phillips

Publications and source records attributed to D M Phillips.

At least 55 records · Page 3Linked to original sources
PubMed1996

Proline-rich tandem repeats of antibody complementarity-determining regions bind and neutralize human immunodeficiency virus type 1 particles.

The proline-rich tandem repeat domain of human mucin MUC1 forms an extended structure containing large repeating loops that are crested by a turn. We show that the repeating-loop structure of MUC1 can be replaced by an antibody complementarity-determining region loop of a human immunodeficiency virus type 1 (HIV-1)-specific neutralizing antibody to create a chimeric, multivalent, mucin-like, anti-HIV-1 compound. We used 8 residues of an antibody molecule to replace 8 of 20 residues of the MUC1 tandem-repeat sequence. The antiviral peptide discussed here contains three copies of a 20-residue tandem repeat, (IYYDYEEDPAPGSTAPPAHG)3, for a total of 60 residues. We demonstrate that the mucin-antibody chimera retains the binding specificity of the parent antibody (monoclonal antibody F58), GPGR of the HIV-1 gp120 V3 neutralizing epitope, and the ability to neutralize virus particles. In inhibition enzyme-linked immunosorbent assay, the mucin-antibody chimeric peptide could inhibit 71 to 84% of binding to a V3 loop peptide by monoclonal antibodies known to be specific for GPGR in the V3 loop. The mucin-antibody chimeric peptide could also inhibit monoclonal antibody binding to native gp120 captured from virus particles. In addition, the chimeric peptide neutralized the homologous HIV-IIIB virus in a standard neutralization assay. The methods of antiviral peptide design and construction presented here are general and theoretically limited only by the size of the antibody repertoire. This approach could be used to synthesize peptides for a variety of therapeutic applications.

Amino Acid Sequence↗
PubMed1996

Directional budding of human immunodeficiency virus from monocytes.

Time-lapse cinematography revealed that activated human immunodeficiency virus (HIV)-infected monocytes crawl along surfaces, putting forward a leading pseudopod. Scanning electron micrographs showed monocyte pseudopods associated with spherical structures the size of HIV virions, and transmission electron micrographs revealed HIV virions budding from pseudopods. Filamentous actin (F-actin) was localized by electron microscopy in the pseudopod by heavy meromyosin decoration. Colocalization of F-actin and p24 viral antigen by light microscopy immunofluorescence indicated that F-actin and virus were present on the same pseudopod. These observations indicate that monocytes produce virus from a leading pseudopod. We suggest that HIV secretion at the leading edges of donor monocytes/macrophages may be an efficient way for HIV to infect target cells.

Actins↗
PubMed1996

Accuracy of automated finger blood pressure devices.

BACKGROUND AND OBJECTIVES: Automated finger blood pressure devices are marketed to consumers as accurate devices to monitor blood pressure. Our study compared the accuracy of these devices to standard blood pressure cuffs. METHODS: Three models were purchased and tested against standard cuff measurement. With the patient relaxed and seated for at least 5 minutes, cuff measurement was performed. The blood pressure was then measured by the three finger devices in quick succession. RESULTS: No statistically significant correlation was shown between cuff measurement and the finger device measurements. CONCLUSIONS: Patients should be cautioned that these devices may not be able to perform as they are marketed.

Adolescent↗
PubMed1995

An assay for HIV infection of cultured human cervix-derived cells.

There is a critical need to develop new strategies to prevent sexual transmission of HIV. Condoms have limited acceptance, and a vaccine may not be available for many years. A vaginal formulation could provide an alternative method if a compound that inhibits sexual transmission of HIV can be identified or synthesized, and if this agent can be formulated for vaginal use. In this report we describe an infection assay for testing compounds that may be useful in a vaginal formulation. This assay system utilizes a cell line (ME-180) derived from the human cervix which, on the basis of morphological features, is an appropriate model of female and male genital and urinary tract epithelia. These cells can be productively infected with HIV upon exposure to HIV-infected T-cell lines. Blocking experiments can be readily carried out in this model because in this p24 ELISA assay system the quantity of virus released by the infected epithelium over a 24-h period is 40 times background.

Cell Line↗
PubMed1995

Sulfated polyanions block Chlamydia trachomatis infection of cervix-derived human epithelia.

Using a cell line derived from the human cervix and a rapid fluorescence cytotoxicity assay, we have shown that Chlamydia trachomatis infection can be blocked by certain sulfated polysaccharides (carrageenan, pentosan polysulfate, fucoidan, and dextran sulfate) and glycosaminoglycans (heparin, heparan sulfate, and dermatan sulfate) but not by other glycosaminoglycans (chondroitin sulfate A or C, keratan sulfate, and hyaluronic acid). The most negatively charged molecules are the most effective at blocking infection. Results of infection at 4 degrees C suggest that sulfated polyanions act by preventing the adherence of chlamydiae to target cells. These and additional blocking studies with enzymes suggest that a heparan sulfate-like glycosaminoglycan on the surface of elementary bodies is involved in the adherence of chlamydiae to target cells, probably through a nonspecific charge interaction or possibly a heparin-binding protein. We previously observed that the same sulfated polysaccharides inhibit transmission of human immunodeficiency virus in vitro and suggested that these compounds could be used in a vaginal formulation to inhibit infection by human immunodeficiency virus. The results of the present study suggest that the same type of formulation may inhibit sexual transmission of chlamydia.

Animals↗
PubMed1995

Activin promotes ovarian follicle development in vitro.

Activin is a protein originally isolated from follicular fluid as a factor stimulating FSH release from the pituitary. The present experiments support the hypothesis that activins may also regulate follicle development by autocrine/paracrine mechanisms. Granulosa-oocyte complexes were isolated by collagenase/dispase dispersion of ovaries from 14- or 21-day-old rats and cultured in serum-free medium. Within 24 h, the cells had spread to form a monolayer. Hormones and growth factors were added at this time. Cell number and thymidine incorporation were measured after an additional 72 h. In the presence of insulin and transferrin, activin-A increased both granulosa cell number and thymidine incorporation more than 2-fold. This effect could be inhibited by follistatin, an activin-binding protein. In addition, activin-A, in the presence of FSH, induced reorganization of follicular structures from monolayer culture of cells from 14-day-old rats and caused cells from primary follicles to develop into large follicle-like structures. These structures contained oocytes, a cumulus layer, an antrum, and a multilayered follicular wall with a diameter of more than 1 mm. Electron microscopy revealed that the cells in the follicle-like structure were connected by gap junctions. Oocytes showed a mature morphology and had closely associated cumulus layers. Dissociation of the follicular wall in these follicle-like structures was induced by the addition of LH, resembling the induction of ovulation in vivo. The findings are important for understanding follicular development and atresia.

Activins↗
PubMed1995

Economic viability of a model rural family practice.

BACKGROUND AND OBJECTIVES: A model rural clinic was established by the Quincy Family Practice Residency Program with the financial support of sponsoring local hospitals. The purpose of the study was 1) to determine the financial viability of such a model practice and 2) to determine the practice's financial effect on the sponsoring hospitals. METHODS: The rural practice was established in a medically underserved area 30 miles from the sponsoring hospitals. A cost analysis of months 7-18 of operation was performed, including an analysis of charges generated at the sponsoring hospitals. Theoretical models of practice to enhance economic viability were explored. RESULTS: The 3,051 office visits fell short of expectations. These visits generated a net practice income of $18,596. Had the practice sought full payment for these visits instead of accepting Medicare assignments, the net income potential would have been $39,182. Growth of the practice until it reached the average size of a typical rural family practice (6,000 annual visits) would produce a net income of $67,113 with Medicare assignments and $103,578 if Medicare assignments were not accepted. Had the practice been a federally designated rural health clinic, a mid-level practitioner with physician supervision could have generated a net practice income of $53,640 for 3,051 visits or $138,863 for 6,000 visits. Referrals from the model clinic for laboratory work, radiology, and hospital admissions generated $9.17 in charges for the sponsoring hospitals for each dollar charged by the clinic. CONCLUSIONS: The financial viability of rural practices is adversely affected by the Medicare reimbursement system. Our model clinic had a positive economic effect on the sponsoring hospitals, suggesting that innovative collaborative sponsorship of such clinics may be mutually beneficial.

Costs and Cost Analysis↗
PubMed1994

Fate of sperm organelles during early embryogenesis in the rat.

This report is part of a continuing study in which we employ monoclonal antibodies to membrane domains and internal organelles of rat spermatozoa in order to trace events during maturation, capacitation, fertilization, and early development. In the present study, we have used immunocytochemistry at the light and EM levels to localize one antibody, 5A5, to the fibrous sheath and a second, 3D5, to the outer mitochondrial membrane. Antibody 5A5 does not stain the fibrous sheath of spermatozoa of rodents other than the rat, while 3D5 can be localized to the outer mitochondrial membrane of rat, hamster, and mouse spermatozoa. In order to follow these antibodies during fertilization and early embryogenesis, we developed a method to stain internal components of zygotes and early embryos. Our findings suggests that the fibrous sheath disappears prior to the first cleavage and that mitochondria can be detected up to the 2-cell stage in mouse and the 4-cell stage in rat.

Animals↗
PubMed1994

Mechanisms of sexual transmission of HIV: does HIV infect intact epithelia?

The prevailing view of sexual transmission of HIV has been that the virus enters the body through lesions in the epithelium of the genital tract. We propose that transmission of HIV can occur via the infection of intact epithelial cells, and that it is mediated by HIV-infected mononuclear cells in genital-tract secretions.

CD4-Positive T-Lymphocytes↗
PubMed1994

Human gamete fusion test: an experimental model for assessing the fusion potential of sperm from nonfertilizing normospermic patients.

OBJECTIVE: To develop an experimental model for assessing the ability of sperm to bind and subsequently fuse with the oolema and to use this test for evaluating the fusion potential of nonfertilizing human sperm. DESIGN: Aged human oocytes (n = 108) were denuded of their zonae and loaded with DNA-specific bisbenzamidazole fluorochrome. Sibling oocytes were inseminated by semen samples from either normospermic patients (study group; n = 12) who have repeatedly failed to achieve fertilization in vitro or patients demonstrating high fertilization rates (control; n = 12). Gamete fusion was ascertained by fluorescent microscopy and validated by scanning electron microscopy. Test results were analyzed in relation to current partial zona dissection treatment outcome. SETTING: Infertility and IVF Unit of an academic tertiary referral medical center and university-based basic research laboratory. RESULTS: In samples achieving fertilization by partial zona dissection (7/12; 9% to 23% fertilization rate), the mean numbers of fused spermatozoa were similar to those of the control (2.1 compared with 2.6) and significantly higher than in the partial zona dissection-failed fertilization subgroup. In six of seven cases in which partial zona dissection yielded embryos, fluorescent spermatozoa were detected on the oolema, whereas in all but one partial zona dissection-failed cases gamete fusion was not observed. CONCLUSIONS: The suggested human gamete fusion test may help focus on specific sperm dysfunction in nonfertilizing patients. It correlates well with the outcome of partial zona dissection-assisted IVF trials and may provide useful information before this treatment is attempted.

Cellular Senescence↗
PubMed1994

Distinctive features of the gametes and reproductive tracts of the Asian musk shrew, Suncus murinus.

Insectivora are of special interest as the most primitive of the eutherian mammals, but essentially nothing is known of their gamete function. In this respect, the Asian musk shrew (Suncus murinus), investigated in the present study, displays many idiosyncrasies. In the epididymis, the giant acrosome undergoes further stabilization, its unusual resilience being especially evident in a "rim" created by a persistent close alignment of the outer acrosomal and overlying plasma membranes. However, until spermatozoa reached a gland on the vas deferens, no post-testicular change was demonstrable in the sperm head surface, the unusual nature of which was indicated by a dorso-ventral differentiation, by an inability to auto-agglutinate or to bind to the homologous zona pellucida, and by an insensitivity to anti-sperm immunoglobulin IgG in fresh serum. At mating, only about 1 x 10(6) spermatozoa are inseminated as far as the anterior vagina with plug formation. Within the small (6 mm) fallopian tube, the isthmus and ampulla are sharply delineated by their contractile activity and epithelial character; there is evidence of some sperm entry into isthmic crypts and a tendency for ipsilateral ovarian control of sperm transport to the tubal ampulla. The cumulus oophorus does not undergo preovulatory mucification and expansion, is characterized by persistent intercellular gap junctions, and is insensitive to hyaluronidase and trypsin. It is unclear how the compact cumulus is penetrated at fertilization. The giant acrosome contains acrosin and an unusually temperature-dependent cumulytic activity; it is intact in motile ampullary spermatozoa but appears to be discharged before reaching the zona pellucida. Since eggs were not penetrated in the presence of ampullary spermatozoa until 4-10 h after ovulation, Suncus spermatozoa spend a long period in the female before they can fertilize. The determinants of sperm function, including capacitation and the acrosome reaction (AR), may depend on a different set of controls in Suncus, perhaps as a legacy of the resilient giant acrosome. This possibility could be examined in other Crociduran and Soricine shrews selected according to acrosome size.

Acrosome↗
PubMed1994

Role of the cytoskeleton in cell-to-cell transmission of human immunodeficiency virus.

We previously observed that when human immunodeficiency virus (HIV)-infected T lymphocytes are added to epithelial cells, they adhere, polarize, and secrete virions unidirectionally onto the epithelium. Epithelial cells subsequently take up virus and become productively infected. We report here that colchicine treatment of T-lymphocyte suspensions induced lymphocyte polarization, redistribution of F-actin into a pseudopod, and secretion of HIV from the pseudopod. Immobilization of T lymphocytes on negatively charged plastic also caused redistribution of F-actin and unidirectional secretion of HIV onto the plastic. As neither colchicine nor adhesion caused an increase in HIV secretion, they apparently act by focusing secretion to the tip of the pseudopod. We speculate that adhesion-induced polar secretion of HIV, from activated mononuclear cells onto epithelia, is a cytoskeleton-mediated process which may be involved in HIV transmission in vivo.

Actins↗