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Biomedical subjects

P Wright

Publications and source records attributed to P Wright.

At least 127 records · Page 7Linked to original sources
PubMed1995

Synthesis and purification in a single column on a high-throughput automated oligonucleotide production system.

Oligonucleotides are synthesized and purified in a single column filled with a mixture of nucleoside-loaded and underivatized, high-cross link, non-swelling polystryene beads. A new oligonucleotide production system has been developed to completely automate-the entire process of sequence entry, phosphoramidite synthesis, cleavage, deprotection, purification, quantitation, and sample collection. Up to 48 primer-length, high-purity oligonucleotides can be produced in a 24 hour period of unattended automation on the ABI 3948 DNA Synthesizer. Synthesis, cleavage, and purification occur within the unique OneStepTM column. Analyses by MicroGel capillary electrophoresis, anion-exchange HPLC, PAGE, and enzymatic digestion/HPLC routinely exhibit > 90% product purity. Stringent PCR, automated fluorescent sequencing, and genetic analysis experiments show the positive effects of the total automation of purified oligonucleotide production.

Base Sequence↗
PubMed1994

In situ hybridization of trkB and trkC receptor mRNA in rat forebrain and association with high-affinity binding of [125I]BDNF, [125I]NT-4/5 and [125I]NT-3.

The TrkB and TrkC receptor tyrosine kinases have been identified as high-affinity receptors for the neurotrophic factors brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT-4/5) and NT-3 respectively. These receptor classes were identified and mapped by the in situ hybridization of antisense riboprobes complementary to portions of the intracellular (tyrosine kinase) or extracellular (ligand-binding) domains of trkB and trkC mRNA, and by the distribution of high-affinity [125I]BDNF, [125I]NT-4/5 and [125I]NT-3 binding sites in adjacent rat brain sections. Both methods showed that TrkB and TrkC receptors are abundant and widely expressed throughout the brain. Kinase or extracellular domain trkC probes labelled neuronal somata in a qualitatively similar manner in virtually every major area of the forebrain. Neither trkC probe labelled non-neuronal cells except for elements within cerebral arteries and arterioles. The kinase domain trkB probe hybridized exclusively to neurons. Neurons expressing trkB were even more widely distributed than those expressing trkC. The extracellular domain trkB probe labelled neurons with the same relative distribution as the trkB kinase domain probe, but also hybridized extensively with non-neural cells, particularly astrocytes, ependyma and choroid epithelium cells. The distribution of [125I]NT-3 binding sites generally resembled that of trkC hybridization, particularly in the neocortex, striatum and thalamus. [125I]BDNF and [125I]NT-4/5 binding sites were more widely distributed and denser than those for [125I]NT-3, and resembled the trkB hybridization pattern. These patterns are consistent with the preferential binding in the brain of TrkC receptors by [125I]NT-3 and of TrkB receptors by [125I]BDNF and [125I]NT-4/5. That the predominantly neuronal patterns of hybridization obtained with kinase and extracellular domain probes for trkC are qualitatively indistinguishable suggests that truncated and full-length forms of TrkC are expressed within extensively overlapping populations of neurons. In marked contrast to TrkC, expression of the full-length and truncated forms of TrkB appears to be largely segregated, being expressed principally on neurons and non-neuronal cells respectively. The abundant and widespread neuronal distribution of full-length, signal-transducing forms of TrkB and TrkC predict that their cognate ligands, BDNF, NT-4/5 and NT-3, may exert direct effects on a large proportion of neurons within the mature brain.

Animals↗
PubMed1994

Neutralizing antibodies to HIV-1 in seronegative volunteers immunized with recombinant gp120 from the MN strain of HIV-1. NIAID AIDS Vaccine Clinical Trials Network.

OBJECTIVE: To evaluate the safety and immunogenicity of the MN strain of recombinant gp120 (MN rgp120) as a vaccine prototype to prevent human immunodeficiency virus (HIV). DESIGN: Double-blind, randomized, placebo-controlled study with subjects vaccinated at 0, 4, 24, and 48 weeks and followed up through 64 weeks. SETTING: The AIDS Vaccine Evaluation Units in St Louis, Mo, Nashville, Tenn, and Rochester, NY, conducted the clinical study. Laboratory studies were conducted at Duke University, Raleigh, NC; data analysis was done by the Data Coordinating and Analysis Center at the EMMES Corporation, Potomac, Md. PARTICIPANTS: Fifty-seven persons seronegative for HIV, at low risk for acquiring HIV infection, and 18 to 60 years of age. INTERVENTIONS: The MN rgp120 vaccine was administered to 12 volunteers each in doses of 100 micrograms, 300 micrograms, or 600 micrograms, and 12 volunteers received a combination of 300 micrograms of MN rgp120 vaccine and 300 micrograms of vaccine from rgp120 of strain IIIB. Nine volunteers received alum adjuvant alone (control). MAIN OUTCOME MEASURES: Safety was assessed by monitoring lymphocyte subsets, serum creatinine, and liver enzymes. Immunogenicity was measured by enzyme-linked immunosorbent assay using the immunogen and synthetic peptide corresponding to the variable region 3 domain of gp120. Functional antibody assays included CD4 binding blocking; antibody-dependent, cell-mediated cytotoxicity; and neutralization of homologous and heterologous HIV strains. RESULTS: No severe adverse reactions occurred. In 33 of 48 volunteers, two doses of vaccine induced antibodies that neutralized the homologous strain HIV-1/MN. Three doses of vaccine induced antibodies that neutralized MN (in 46 of 48 volunteers), SF-2 (in 45 of 48 volunteers), or IIIB strains of HIV-1 (in 30 of 48 volunteers). CONCLUSION: The vaccines were safe and immunogenic. Multiple injections of vaccine broadened and increased the neutralizing antibody response.

AIDS Vaccines↗
PubMed1994

Expression and regulation of a glutamate receptor subunit by bFGF in oligodendrocyte progenitors.

Oligodendrocyte progenitor cells (O-2A) express both kainate-preferring and AMPA-preferring glutamate receptors (Gallo et al., Soc. Neurosci. Abstr., 18:653, 1992b; Gallo et al., 1994). The expression and regulation of the GluR-4c, AMPA-preferring subunit by growth factors was studied by Northern blot analysis of total RNA from purified rat cortical O-2A progenitors. Differently from cortical neurons, O-2A progenitors only expressed two high molecular weight GluR-4c transcripts (6.2 and 4.2 kb), as observed also in cultured astrocytes. Basic fibroblast growth factor (bFGF) increased GluR-4c transcript levels in O-2A progenitors and its effects were not mimicked by platelet derived growth factor (PDGF) or fetal calf serum. Therefore, bFGF may regulate O-2A progenitor responsiveness to glutamate during development through the expression of glutamate receptor subunits.

Animals↗
PubMed1994

The value of biopsies in the evaluation of chronic progressive conjunctival cicatrisation.

BACKGROUND: Chronic progressive conjunctival cicatrisation is poorly understood, and therapy of this condition remains difficult. This study assessed the value of immunohistochemical investigations in the evaluation of patients who present with chronic cicatrising conjunctivitis similar to cicatricial pemphigoid (CP). METHODS: Bulbar conjunctival biopsies from 36 patients with acute (n = 5), subacute (n = 13) and chronic (n = 18) ocular disease were studied. The biopsy was retaken in 7 patients to evaluate the present immunological findings in comparison with a biopsy more then 5 years ago. All the specimens were investigated for the presence of immunoglobulins and complement at the epithelial basement membrane, and the phenotype of the inflammatory cellular infiltrate was analysed. Twenty-nine patients were evaluated for the presence of circulating IgG-anti-basement membrane zone antibodies. RESULTS: CP was confirmed by immunoglobulins and/or complement deposition at the epithelial basement membrane in 11 patients (31%). IgA was found to be the most frequent deposit. Eleven CP patients, mainly those with active or "burnt-out" disease, showed absence of immunoglobulins and/or complement at the conjunctival basement membrane. In 14 of 36 patients, conjunctival cicatrisation was subsequently felt to be caused by conditions other than CP. The cellular phenotype in the subepithelial conjunctiva was unspecific, but in CP the disease activity was reflected by the number of neutrophils and macrophages. Circulating IgG antibodies were found in none of the patients' serum. CONCLUSION: Immunoglobulin and/or complement deposition at the epithelial basement membrane confirms the diagnosis of mucous membrane pemphigoid. Their absence, however, does not rule it out and is a frequent feature in very active conjunctival disease or after immunosuppressive treatment. The analysis of the cellular phenotype in mucous membrane pemphigoid may be useful in the assessment of disease activity but does not help in determining the underlying disease process causing the cicatrising conjunctivitis.

Acute Disease↗
PubMed1994

An association between sputum eosinophilia and carcinoma of the lung: a study of 549 patients.

A prospective 11 year study of sputum cytology in 5,475 patients with respiratory diseases other than asthma or Loeffler's syndrome showed that carcinoma of the lung was the commonest single condition associated with a sputum eosinophilia: it occurred in 68 (12.4%) of the 549 patients with pulmonary carcinoma. While clearly not a diagnostic finding, sputum eosinophilia should stimulate, in appropriate cases, a further search for carcinoma. The cause or causes of the eosinophilia are not known at present but the body's reaction to malignancy is a topical subject of study worldwide.

Eosinophils↗
PubMed1994

Simplified procedure for making gold occlusal surfaces on denture teeth.

The procedure described is used to reproduce, in gold, the occlusal morphology of complete and removable partial denture teeth or those of an implant-supported prosthesis. The gold occlusal surfaces are made after all adjustments are completed and the occlusion is harmonious. An acrylic resin strut reinforces the wax patterns, and a reline jig is used to accurately stamp out the occlusal anatomy in wax. Careful adherence to the step-by-step procedure is required to achieve an excellent result.

Dental Casting Technique↗
PubMed1994

Drug resistance and Acanthamoeba keratitis: the quest for alternative antiprotozoal chemotherapy.

Trophozoites and cysts of 20 isolates of Acanthamoeba from the cornea and five from related samples were tested in vitro for sensitivity to ten drugs (three aromatic diamidines, two aminoglycosides, two macrolides, a polyene macrolide antibiotic, an organoarsenical and an antimetabolite) and two cationic antiseptics (chlorhexidine and polyhexamethylene biguanide, PHMB). Only chlorhexidine and PHMB showed uniform amoebacidal activity. Aromatic diamidines (pentamidine isethionate, propamidine isethionate and diminazene aceturate) generally proved effective against both forms of the amoeba; only pentamidine gave synergy with the biguanide while propamidine gave an additive effect. Other drugs tested proved erratic or ineffective against different isolates. Chlorhexidine alone, or together with propamidine, was subsequently used in two patients with proven Acanthamoeba keratitis; the causative isolates were sensitive to the individual compounds and to the combination in vitro. The treatment provided resolution of the clinical disease; amoebae were shown to be nonviable by histology and culture. The combination of chlorhexidine and propamidine is recommended for treatment of proven Acanthamoeba keratitis.

Acanthamoeba↗
PubMed1994

Primary influenza A virus infection induces cross-reactive antibodies that enhance uptake of virus into Fc receptor-bearing cells.

Sera of young children who had had a primary infection with influenza A virus or were immunized with a live attenuated influenza A virus vaccine were examined for antibody responses that neutralized virus or enhanced uptake of virus into Fc receptor-bearing cells, because antibodies that enhance uptake of influenza virus into Fc receptor-bearing cells have been reported using mouse immune serum and monoclonal antibodies. The neutralizing antibody titers to the homologous infecting virus and to another H1N1 virus isolated several years later were higher after natural infection than after infection with the live attenuated virus. Natural infection and the attenuated vaccine induced antibodies that enhanced uptake of homologous virus and H1N1 virus isolated several years later. These results demonstrate that primary influenza A virus infection results in the induction of infection-enhancing antibodies.

Animals↗
PubMed1994

An association study of debrisoquine hydroxylase (CYP2D6) polymorphisms in schizophrenia.

The cytochrome P450 mono-oxygenases are a group of enzymes that metabolize a variety of exogenous and endogenous compounds, some of which are potentially toxic. Individual variations in the metabolism of potential toxins could influence susceptibility to disorders having genetic and environmental components, such as schizophrenia. The frequency of two common mutant alleles of the gene for the cytochrome P450 enzyme debrisoquine-4-hydroxylase (CYP2D6) was determined in 264 Caucasian schizophrenic patients and 217 controls, using the polymerase chain reaction and restriction enzyme digestions. The patient and control samples showed no significant deviation from Hardy-Weinberg equilibrium and the frequency of each mutant allele (CYP2D6A and CYP2D6B) did not differ between patients and controls.

Alleles↗
PubMed1994

AMMONIA EXCRETION IN FRESHWATER RAINBOW TROUT (ONCORHYNCHUS MYKISS) AND THE IMPORTANCE OF GILL BOUNDARY LAYER ACIDIFICATION: LACK OF EVIDENCE FOR Na+/NH4+ EXCHANGE

Net ammonia fluxes (JAmm) were measured in adult freshwater rainbow trout in vivo under a variety of conditions designed to inhibit unidirectional sodium uptake (JinNa; low external [NaCl], 10(-4) mol l-1 amiloride), alter transbranchial PNH3 and NH4+ gradients [24 h continuous (NH4)2SO4 infusion, or exposure to 1 mmol l-1 external total ammonia at pH 8] and prevent gill boundary layer acidification (5 mmol l-1 Hepes buffer). Inhibition of JinNa with amiloride or low external [NaCl] under normal conditions reduced JAmm by about 20 %, but did not prevent the net excretion of ammonia during exposure to high concentrations of external ammonia. Increasing the buffer capacity of the ventilatory water with Hepes buffer (pH 8) reduced JAmm by 36 % and abolished the effect of amiloride on ammonia excretion. No evidence could be found to support a directly coupled apical Na+/NH4+ exchange. We suggest that any dependence of ammonia excretion on sodium uptake is caused by alteration of transbranchial PNH3 gradients within the gill microenvironment secondary to changes in net H+ excretion. Under normal conditions (pH 8, low external ammonia) gill boundary layer acidification facilitates over one-third of the total ammonia excretion. During exposure to high concentrations of external ammonia in poorly buffered water, estimates of transbranchial PNH3 gradients from measurements of bulk water pH and total ammonia concentration (TAmm) may be grossly in error because of boundary layer acidification. Prevention of boundary layer acidification with Hepes buffer during exposure to high cocncentrations of external ammonia revealed that the local transbranchial PNH3 gradient at the gill may in fact be positive (blood to water), negating the need for an active NH4+ transport mechanism. In freshwater trout, NH3 diffusion may account for all ammonia excretion under all experimental conditions used in the present study.

Journal Article↗
PubMed1994

[Immunohistologic findings in chronic cicatricial conjunctivitis].

BACKGROUND: Chronic progressive conjunctival cicatrization is found in some mucocutaneous disorders (cicatricial pemphigoid, linear IgA disease) and after long-term treatment with certain topical medications (pseudo-pemphigoid). Little is known about the mechanisms of conjunctival shrinkage, and therapy for these conditions remains difficult. OBJECTIVES: To elucidate the immune mechanisms and assess the main factors involved in conjunctival scar tissue formation in patients with chronic progressive conjunctival cicatrization. PATIENTS AND METHOD: We examined 14 bulbar conjunctival biopsy specimens from patients with chronic progressive conjunctival cicatrization (8 with benign mucous membrane pemphigoid confirmed by biopsy, 4 with the ocular features of benign mucous membrane pemphigoid and 2 with pseudopemphigoid) and 10 biopsies from matched healthy individuals: 1.5 mm sections of glycol methacrylate embedded tissue were analysed with the aid of a panel of monoclonal antibodies. MAIN RESULTS: Cell counts in the subepithelial substantia propria showed a marked increase in T-cells over normal controls (up to 30-fold). Among the T-cell subsets, there were more CD8 than CD4-positive cells observed. Only about 5% of the T-cells were activated (IL-2 receptor-positive). Macrophages were--as in normal tissues--the second most predominant cell. The absolute number was 2-3 times as high in diseased conjunctiva as in controls. There was increased expression of MHC II molecules on macrophages, lymphocytes und fibroblasts. The numbers of B-cells and NK were not increased. CONCLUSIONS: The analysis of the cellular infiltrate showed nonspecific immunopathological characteristics. Thus, the cellular infiltrate gives no explanation for the progressive cicatrization. There is evidence that soluble factors, especially fibrogenic cytokines, play an important role.

B-Lymphocytes↗
PubMed1994

Psychological considerations for women in sports.

In this article, we have tried to provide a context in which to understand the complexities of the psychological experience of being female and being an athlete. To this end, we have included general information about the socialization process, as well as a more detailed discussion of sports socialization and the impact of external influences (such as the media and role models) on the activities of young women. Information about the psychological characteristics of women athletes was provided as were brief descriptions of a number of issues common to the experience of athletes in general and the female athlete in particular. This is an exciting time for women in sports; laws are changing, opportunities have become available, and women are discovering their athletic potential. The women athlete also has choices that were not available to previous generations. It is a time of discovery as we learn what the female athlete is capable of accomplishing. "We" includes all of us, as coaches, parents, friends, the media, treating professionals, fans, and young athletes themselves. In some ways, what we learn about women athletes will be similar to what is expected in male athletics; however, the female athlete will bring a whole new set of attributes and stylistic differences to sport. It will be important not to limit her with our expectations; rather, we must encourage her to excel to her fullest capabilities.

Adolescent↗
PubMed1994

Overlapping and distinct actions of the neurotrophins BDNF, NT-3, and NT-4/5 on cultured dopaminergic and GABAergic neurons of the ventral mesencephalon.

The neurotrophins brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5) were compared for their effects in promoting the survival and/or regulation of expression of phenotypic markers of dopaminergic and GABAergic neurons in cultures derived from embryonic rat ventral mesencephalon. Dopaminergic neuron number and phenotypic expression were monitored by tyrosine hydroxylase (TH) immunocytochemistry, and measurement of high-affinity dopamine uptake activity and dopamine content, respectively. High-affinity GABA uptake, glutamic acid decarboxylase (GAD) activity, and endogenous GABA content were used to detect GABAergic neurons. Seven days of treatment with either BDNF or NT-3 resulted in dose-dependent increases in the number of TH-positive neurons, with maximal responses of 3-fold and 2.3-fold, respectively. Dopamine uptake activity and dopamine content were similarly increased. The effects of BDNF and NT-3 on dopamine uptake activity showed no additivity. NT-4/5 treatment elicited the greatest increase (7-fold) in the number of TH-positive neurons, as well as a 2.6-fold increase in dopamine content. In marked contrast to BDNF or NT-3, NT-4/5 had no effect on dopamine uptake capacity. BDNF, NT-3, or NT-4/5 also produced dose-dependent elevations of 2-3-fold in GABA uptake activity. These effects were not additive. GAD activity was increased by BDNF (1.8-fold) and NT-3 (threefold) treatment, but not by NT-4/5, whereas GABA content was increased to a similar extent by all three neurotrophins. NGF had no effect on any of the parameters measured in this study. Northern analyses indicated that the mRNAs encoding TrkB and TrkC, the functional high-affinity receptors for BDNF and NT-4/5, and NT-3, respectively, are expressed in the substantia nigra of adult rat brain, as well as in cultures of developing ventral mesencephalon. Taken together, our results indicate that BDNF and NT-3 have broadly similar effects in promoting the survival and differentiated phenotype of both dopaminergic and GABAergic neurons of the developing substantia nigra. Although BDNF and NT-4/5 are thought to act through the same high-affinity receptor, TrkB, it is evident that these two neurotrophins have distinct as well as overlapping actions toward mesencephalic dopaminergic or GABAergic neurons.

Animals↗