Biomedical subjects

R Willey

Publications and source records attributed to R Willey.

At least 19 recordsLinked to original sources

PubMed1992

Molecular characterization of a polymerase mutant human immunodeficiency virus.

Explore the source record for details and available documents.

Amino Acid Sequence↗

PubMed1992

In-vivo comparisons of clot formation on titanium and hydroxyapatite-coated titanium.

We investigated in vivo clot formation on the surface of hydroxyapatite (HA)-coated titanium (Ti) implants and on non-coated Ti implants. Immediately after tooth extraction implant samples were inserted into the blood clot, in the same extraction site, for 1, 30, 60, or 120 seconds. Samples were processed for scanning electron microscopy (SEM). Qualitative observations of clotting topography were made by direct SEM viewing. Neither of the implant surfaces appeared to differ markedly in the degree of clotting during the 120 seconds of implantation; they revealed very early clot formation and limited clot attachment. These results were compared to the findings obtained in a previous study using identical methods with an intact periodontal ligament (PDL), root planed roots, and roots planed and treated with pH 1 citric acid. The PDL surface had the most rapid clot formation at all time periods. By 120 seconds, all root surfaces had completed clot formation.

Alloys↗

PubMed1988

Scanning electron microscopy observations of initial clot formation on treated root surfaces.

This study presents the morphological sequence of events in initial blood clot formation on various root surfaces of freshly extracted human teeth. Four teeth with periodontal disease (PD) and three teeth without PD were extracted and the roots sectioned into halves. Those root surfaces with PD had four treatment areas: (1) intact periodontal ligament (PDL), (2) unplanned PD, (3) PD plus planed, (4) PD plus planed plus application of pH 1 citric acid (CA). The roots with no PD had three treatment areas: (1) intact PDL, (2) planed, (3) planed plus CA. Both root halves were reinserted together into the original extraction site. Each root half was then removed at either zero, one, two or four minutes and prepared for scanning electron microscope (SEM) evaluation. SEM observations suggested that plasma proteins were deposited initially on all root surfaces. Platelets and erythrocytes enmeshed in fibrin deposited most rapidly and consistently over the plasma protein layer where intact PDL was present. Similar observations were noted on the planed plus CA surfaces and appeared to occur at an earlier time than on the planed-only surfaces. A constant feature at all time periods was the absence of organized clot formation over the plaque-free zone of the PD root surfaces. By two minutes all surfaces, except the plaque-free zone of the PD area, appeared to have clot lysis occurring. While clot formation appeared to occur more rapidly over surfaces in the non-PD roots, no marked morphological differences in clot formation were observed between PD and non-PD teeth with similar root surface treatments.

Blood Coagulation↗

PubMed1987

Molecular characterization of a polymerase mutant human immunodeficiency virus.

A cell line (8E5) containing a single defective copy of human immunodeficiency virus proviral DNA and producing noninfectious viral particles lacking reverse transcriptase (RT) and endonuclease proteins has recently been described (Folks, et al., (1986b) J. Exp. Med. 164, 280-290). In this report, the mutation in a full-length molecular clone of the provirus (p8E5) was mapped to a 1931-bp region of the pol gene encoding RT. The nucleotide sequence of this segment revealed a 1-base deletion 301 codons from the common amino terminus of the 64- and 51-kDa RTs. Expression of the p8E5 RT segment in Escherichia coli generated an enzymatically inactive and truncated 33-kDa protein.

Amino Acid Sequence↗

PubMed1987

Human retroviral sequences on the Y chromosome.

Novel endogenous human retroviral sequences were cloned by low-stringency hybridization, using the pol gene of endogenous human retrovirus 51-1. One clone, lambda NP-2, contained gag, pol, env, and long terminal repeat sequences related to the corresponding portions of clone 51-1 and the closely related full-length endogenous human retrovirus 4-1. The sequence of the env gene of NP-2 was 73% homologous to that of 4-1. Genomic Southern blots of male and female DNAs showed that NP-2 is located on the Y chromosome and that the Y chromosome also contains one other sequence closely related to the env and 3' flanking regions of NP-2. Conservation of flanking DNA suggests that the second Y chromosome copy of the NP-2 env sequence arose by gene duplication rather than provirus insertion.

Base Sequence↗

PubMed1986

Production of acquired immunodeficiency syndrome-associated retrovirus in human and nonhuman cells transfected with an infectious molecular clone.

We constructed an infectious molecular clone of acquired immunodeficiency syndrome-associated retrovirus. Upon transfection, this clone directed the production of infectious virus particles in a wide variety of cells in addition to human T4 cells. The progeny, infectious virions, were synthesized in mouse, mink, monkey, and several human non-T cell lines, indicating the absence of any intracellular obstacle to viral RNA or protein production or assembly. During the course of these studies, a human colon carcinoma cell line, exquisitely sensitive to DNA transfection, was identified.

Animals↗

PubMed1986

Extravascular clot formation and platelet activation on variously treated root surfaces.

The platelet attachment and activation potential of a variety of treated, human root surfaces was studied employing an established in vitro method for determining thrombogenicity. In addition, scanning electron microscopic observations were made of the morphological appearance of blood components in initial clot formation on root surfaces containing periodontal ligament (PDL). For the platelet study, the crowns were removed from freshly extracted teeth with and without periodontal disease (PD) and the roots were sectioned. The following surface conditions were created: (1) PDL present, (2) PD, (3) PD planed, (4) PD planed and demineralized, (5) Condition 4 treated with collagenase. All conditions were incubated with Indium-1 ll-labeled platelets with and without the addition of prostacyclin, an inhibitor of platelet activation. It was observed that the greatest number of attached platelets were found in Condition 1, that platelet activation was significantly enhanced in Condition 4 and this effect was reversed by Condition 5. The scanning electron microscopic observations were made on freshly extracted teeth with an intact PDL in which the roots were sectioned and either reinserted immediately into the extraction site or incubated in platelet-rich plasma. It was seen that platelets were involved early in clotting and activated by this surface. This study suggests the possible use of platelet attachment and activation as an indicator for root surface thrombogenicity and perhaps of the fibrous attachment potential.

Blood Coagulation↗

PubMed1984

Scanning electron microscopic studies of root dentin surfaces treated with citric acid, elastase, hyaluronidase, pronase and collagenase.

The effect of topical application of various enzymes to citric acid-demineralized root surface dentin was evaluated using the scanning electron microscope. All of the enzyme treatments appeared to expose more collagen than demineralization alone. Collagenase application appeared to clear all ground substance from the collagen fibrils and may have hydrolyzed some of the fibrils themselves. The other enzymes appeared to clear partially the intercollagenous ground substance.

Citrates↗

PubMed1978

Body-wise with yoga.

Explore the source record for details and available documents.

Physical Exertion↗

PubMed1978

Circulating inhibitors of blood coagulation associated with procainamide-induced lupus erythematosus.

We studied a patient being treated with procainamide in whom we observed a high antinuclear antibody titer and prolonged activated partial thromboplastin (PTT), prothrombin (PT), and Stypven times (ST). Serum antibody concentrations against single-stranded DNA were elevated while those aginst native DNA were not elevated, suggesting the procainamide-induced lupus syndrome. Dilution of the patient's plasma with normal plasma failed to correct the PTT and PT, indicating the presence of an inhibitor(s) to blood coagulation. The anticoagulant activity was associated with the IgG fraction of the patient's serum. Addition of purified or partially purified human factors IX, X, VIII, VII, XIa, prekallikrein, high molecular weight kininogen, or phospholipids to the patient's plasma failed to correct the PTT, PT, or ST; however, purified human factor XII and prothrombin corrected the PTT and ST, respectively. These results indicate that production of antibodies directed against antigenic determinants on coagulation proteins can be a manifestation of procainamide-induced lupus erythematosus.

Blood Coagulation↗

PubMed1978