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Biomedical subjects

A Wolfe

Publications and source records attributed to A Wolfe.

14 recordsLinked to original sources
PubMed1995

Inhibition of human immunodeficiency virus integrase by bis-catechols.

The human immunodeficiency virus type 1 (HIV-1) integrase protein is required for the productive infection of T-lymphoid cells in culture (R. L. LaFemina, C. L. Schneider, H. L. Robbins, P. L. Callahan, K. LeGrow, E. Roth, W. A. Schleif, and E. A. Emini, J. Virol. 66:7414-7419, 1992). This observation suggests that chemical inhibitors of integrase may prevent the spread of HIV in infected individuals. In our search for such potential chemotherapeutic agents, we observed that beta-conidendrol inhibits both the sequence-dependent and sequence-independent endonucleolytic activities of integrase with comparable potencies in vitro (50% inhibitory concentration, 500 nM). Structurally related compounds tested for their abilities to inhibit integrase generated a limited structure-activity analysis which demonstrated that potency is associated with the bis-catechol structure: two pairs of adjacent hydroxyls on separate benzene rings. beta-Conidendrol did not inhibit several other endonucleases and/or phosphoryltransferases. Although beta-conidendrol was not effective in preventing HIV-1 infection in cell culture, the in vitro data demonstrate that it is possible to identify selective agents targeted against this essential HIV-1 function.

Base Sequence↗
PubMed1995

CheA, CheW, and CheY are required for chemotaxis to oxygen and sugars of the phosphotransferase system in Escherichia coli.

We carried out studies with Escherichia coli to determine the site at which the methylation-independent pathways for taxis to oxygen and to sugars of the phosphoenolpyruvate:sugar phosphotransferase transport system converge with the methylation-dependent chemotaxis pathways. Using genetic reconstitution of the pathways in a null strain, we determined that all pathways examined required the products of the genes cheA, cheW, and cheY. Thus, we conclude that both the methylation-independent and methylation-dependent pathways converge at CheA, the histidine kinase product of cheA.

Bacterial Proteins↗
PubMed1995

A case management program for chemically dependent clients with multiple needs.

As part of a 3-year federal demonstration project, San Francisco health clinics provided case management services to chemically dependent individuals who were low-income and often homeless. Many of those participating in the project had also been diagnosed with HIV infection and/or mental illness. The intent of the demonstration project was to use case management as a mechanism for strengthening the linkages between substance abuse treatment and primary care systems. Case management was adopted as the catalyst for increased communication between medical personnel and other service providers to develop a more comprehensive approach to responding to the myriad of client needs. A specially designed management information system (MIS) was developed to help document client information and case management activities, as well as provide a tickler system to improve client continuity. This report integrates both qualitative and quantitative findings to provide a context for understanding case management activities, client problems and successes, and the systemic problems facing clients and case managers in linking primary care, substance abuse treatment, and mental health services.

Adolescent↗
PubMed1994

Large-scale production and characterization of recombinant human immunodeficiency virus type 1 Nef.

Sequences encoding the 27K and 25K nef gene products (Nef 27 and Nef 25) were amplified by PCR from a human immunodeficiency virus type 1 infectious clone and subcloned directly into Escherichia coli, yeast and baculovirus expression vectors. The yeast- and baculovirus-derived Nef had native N termini but the expression levels were low. The expression levels of the E. coli-derived glutathione S-transferase-Nef fusion proteins were very high and a major portion was soluble. Large-scale production of E. coli-derived Nef 27 and Nef 25 was carried out by growing recombinant cells in a fermenter under fed-batch conditions followed by affinity purification on glutathione-Sepharose before and after thrombin cleavage. Large quantities of highly purified recombinant Nef proteins have been produced for functional and structural studies. Under non-reducing conditions both Nef 27 and Nef 25 existed as a mixture of monomers, dimers and small amounts of higher oligomers, but when reduced were monomeric. The highly purified Nef proteins had no G protein activities, however Nef 27 was biologically active. When electroporated into uninfected CD4+ T lymphocytes both E. coli-derived Nef 27 and yeast-derived myristylated Nef 27 down-regulated the surface expression of CD4, demonstrating that this method can be used to assess the biological activity of purified recombinant Nef.

Base Sequence↗
PubMed1993

Differential gonadotropin responses to N-methyl-D,L-aspartate in intact and castrated male rats.

Peripheral administration of N-methyl-D,L-aspartate (NMA), a neuroexcitatory amino acid agonist, probably stimulates LH release through an increase in endogenous LHRH secretion. In the present study, NMA and a potent LHRH antagonist were used to determine the degree to which release of FSH is similarly dependent upon the acute secretion of LHRH. A second aim was to compare responsiveness of LHRH neurons to NMA in castrated and intact male rats. Adult male rats were castrated (n = 10) or sham castrated (n = 11) on the morning of Day 0. After 8 days, rats were fitted with atrial catheters between 0900 and 1200 h; at 2100 h they received s.c. either oil vehicle or 100 micrograms of an LHRH antagonist. Starting at 0900 h on Day 9, 0.5-ml blood samples were collected every 10 min for 3 h. After 1 h of sampling each animal received i.v. 5 mg of NMA in 0.5 ml 0.9% saline. An hour later each rat received i.v. 500 ng of LHRH in 0.5 ml saline. Plasma LH, FSH, and prolactin (PRL) levels were determined by RIA. In the oil-treated sham castrates, mean plasma LH levels were increased by 110% (p < 0.01) within 10 min and remained elevated for 30 min after the injection of NMA. The profile of this LH secretory response was similar to or slightly more robust than endogenous LH pulses observed previously. The NMA-induced LH release was completely blocked by pretreatment with LHRH antagonist. In both oil- and antagonist-treated sham-castrated rats, NMA administration failed to elicit a concomitant increase in plasma FSH levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Correlating infectious outcome with clinical parameters of 1130 consecutive febrile infants aged zero to eight weeks.

The study objectives were to characterize the infectious outcomes and associated clinical parameters of a large group of febrile young infants who received outpatient sepsis evaluation. This retrospective review of consecutive cases during a seven-year period was set in an urban pediatric emergency department. Febrile infants, aged zero to eight weeks, were the participants. All received a standard evaluation for sepsis, including complete blood count/blood culture, lumbar puncture/cerebrospinal fluid culture, and urinalysis/urine culture. Of 1130 patients, 447 (42%) were aged zero to four weeks, and 683 (58%) were aged four to eight weeks. In 96 cases (8.5%), a bacterial pathogen was isolated by culture of cerebrospinal fluid, blood, urine, or stool; 58% were aged zero to four weeks and 42% were aged four to eight weeks. The rate of positive cultures per patient age was doubled in those aged zero to four weeks (12%) compared with those aged four to eight weeks (6%). The 49 cases of invasive bacterial infections (bacterial meningitis/bacteremia) were most commonly associated with lower degrees of fever, as slightly over one half (25/49) had temperature < 39 degrees C. The most common pathogens of invasive bacterial infection were group B streptococcus and Escherichia coli, accounting for 33 of 49 cases (67%); the most common pathogens of invasive bacterial infection in older children (Haemophilus influenzae type b and Streptococcus pneumoniae) were relatively underrepresented, accounting for only five of these 49 (10%) cases.

Age Factors↗
PubMed1987

Polycyclic aromatic hydrocarbons physically intercalate into duplex regions of denatured DNA.

We have investigated the physical binding of pyrene and benzo[a]pyrene derivatives to denatured DNA. These compounds exhibit a red shift in their absorbance spectra of 9 nm when bound to denatured calf thymus DNA, compared to a shift of 10 nm when binding occurs to native DNA. Fluorescence from the hydrocarbons is severely quenched when bound to both native and denatured DNA. Increasing sodium ion concentration decreases binding of neutral polycyclic aromatic hydrocarbons to native DNA and increases binding to denatured DNA. The direct relationship between binding to denatured DNA and salt concentration appears to be a general property of neutral polycyclic aromatic hydrocarbons. Absorption measurements at 260 nm were used to determine the duplex content of denatured DNA. When calculated on the basis of duplex binding sites, equilibrium constants for binding of 7,8,9,10-tetrahydroxy-7,8,9,10-tetrahydro-benzo[a]pyrene to denatured DNA are an order of magnitude larger than for binding to native DNA. The effect of salt on the binding constant was used to calculate the sodium ion release per bound ligand, which was 0.36 for both native and denatured DNA. Increasing salt concentration increases the duplex content of denatured DNA, and it appears that physical binding of polycyclic aromatic hydrocarbons consists of intercalation into these sites.

DNA↗
PubMed1987

Tumors secreting human TNF/cachectin induce cachexia in mice.

Anorexia and weight loss are serious complications that adversely effect the prognosis of cancer patients. It has been suggested that TNF/cachectin may cause cachexia. To determine if TNF/cachectin can induce progressive weight loss in tumor-bearing animals, a clone of the human TNF/cachectin gene was isolated and inserted into a mammalian expression vector. This construct was transfected into CHO cells, and a cell line (CHO/TNF-20) that secretes TNF/cachectin was isolated. A cell line (CHO/CMV-Neo) that contains the same expression vector without the TNF/cachectin gene was also isolated. Nude mice injected intraperitoneally with CHO/TNF-20 cells died more quickly than mice injected with CHO/CMV-Neo cells. Eighty-seven percent of mice inoculated intramuscularly with CHO/TNF-20 cells developed severe cachexia and weight loss. All mice bearing CHO/CMV-Neo tumors maintained or increased their body weight. We conclude that mice bearing tumors that secrete TNF/cachectin develop progressive wasting and die more quickly than mice bearing control tumors.

Animals↗
PubMed1975

Letter: Z-plasty.

Explore the source record for details and available documents.

Cicatrix↗
PubMedDate not supplied

Factors contributing to helical shape determination and maintenance in Bacillus subtilis macrofibres.

Bacillus subtilis, normally a rod-shaped organism, can grow in the form of a helix with pitch ranging over a spectrum from tight right-handed to tight left-handed depending upon the growth environment and genetic composition of the strain. Five factors have been identified which contribute either to the helical shape deformation or its maintenance: 1) a biomechanical component involving blocked rotation during growth; 2) cell wall polymer conformation; 3) a protein(s) concerned with the left-hand form produced at high temperature; 4) electrostatic aspects of the cell wall; and 5) water, as it affects the mechanical properties of cell walls and the structure of cell wall polymers. The findings are compatible with a model in which the cell wall polymers are inserted in helical orientation along the cylindrical portion of the cell during growth.

Bacillus subtilis↗
PubMedDate not supplied

The nurse's role in office hysteroscopy.

In recent years, hysteroscopy has been developed to provide physicians with direct visibility of the uterine cavity. Using carbon dioxide gas as a distending medium, office hysteroscopy has few side effects for women. It is also more cost effective than outpatient surgery. The nurse's role is pivotal in simplifying office hysteroscopy through empathetic preparation and support of women, careful planning, procurement of necessary items, and finally, conscientious care of the instruments.

Female↗