PubMed Health⌕ Search

Biomedical subjects

A Fox

Publications and source records attributed to A Fox.

At least 37 records · Page 2Linked to original sources
PubMed1997

Pharmacokinetics of prostaglandin E1 and its main metabolites after intracavernous injection and short-term infusion of prostaglandin E1 in patients with erectile dysfunction.

PURPOSE: Alprostadil (prostaglandin E1) is the preferred monotherapy for intracavernous injection in the diagnosis and treatment of erectile dysfunction. Our study was designed to evaluate whether there is a difference in the pharmacokinetics of prostaglandin E1 and its main metabolites after intracavernous injection or short-term intravenous infusion. In addition, we also investigated the influence of the erectile response on prostaglandin E1 kinetics after intracavernous injection. MATERIALS AND METHODS: A total of 24 patients with erectile dysfunction received, in a randomized order at an interval of 5 hours, an intracavernous injection or a 30-minute intravenous infusion of 20 microg. of alprostadil alfadex (prostaglandin E1). Venous blood samples were obtained 5 minutes before and at various times after the applications. We used highly sensitive gas chromatography/double-mass spectrometry method to measure prostaglandin E1 and its metabolites in plasma. RESULTS: We demonstrated the presence of relevant systemic blood levels of prostaglandin E1 and its metabolites immediately after intracavernous injection. We found significantly lower systemic prostaglandin E1 concentrations between 7 and 20 minutes after intracavernous injection in patients with an erectile response compared with those without. CONCLUSIONS: We found significant systemic concentrations of prostaglandin E1 and its metabolites after intracavernous injection. The systemic presence did not lead to significant changes in vital signs.

Alprostadil↗
PubMed1997

Regulation of adenosine concentration and cytoprotective effects of novel reversible adenosine deaminase inhibitors.

The physiological role of adenosine (Ado) is well known. Although a number of pharmacological attempts have been made to manipulate Ado concentrations in ischemic conditions in different tissues, none have been clinically accepted up to now, mostly due to insufficient elevation of Ado concentrations or unacceptable toxicity. In this study, we evaluated the biochemical and pharmacological actions of several novel erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) analogs to identify new reversible adenosine deaminase (ADA) inhibitors with potential clinical utility. In cell culture experiments, these compounds elevate cellular Ado concentrations under conditions of simulated ischemic stress but very little, if any, under normoxic conditions. Two compounds were selected for study: 9'-chloro-EHNA (CPC-405) and 9'-phthalimido-EHNA (CPC-406), which specifically inhibit ADA in cell-free preparations as well as in intact cells. CPC-405 and CPC-406 do not affect adenosine kinase activity, and they do not affect adenosine transport (influx). CPC-405 and CPC-406 are also more potent than EHNA in elevating adenosine release from human astrocytoma cells and bovine heart microvascular endothelial cells in 2-deoxyglucose-simulated ischemia or under anaerobic conditions. Inhibition of adenosine deaminase by CPC-405 or CPC-406, as well as the 2'-deoxyadenosine toxicity expressed in the presence of these ADA inhibitors, is reversed when the inhibitors are removed by washing the cells. In the isolated rat heart model of ischemia, these novel ADA inhibitors showed enhanced recovery of left ventricular end-diastolic pressure, left ventricular developed pressure, +dP/dtmax and -dP/dtmax. In the rat hippocampal slice model of hypoxia, these compounds also showed neuroprotective effects on CA1 hypoxic injury. In conclusion, these novel ADA inhibitors may represent clinically useful Ado elevating compounds that show cardioprotective, as well as neuroprotective, effects. Also, their potential for immunotoxicity, if any, appears to be transient in nature, representing an important clinical advantage compared with tight-binding ADA inhibitors such as deoxycoformycin.

Adenine↗
PubMed1996

Characterization of PCR products from bacilli using electrospray ionization FTICR mass spectrometry.

A procedure for rapid purification of polymerase chain reaction (PCR) products allowing precise molecular weight determination using electrospray ionization-Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry is described. PCR amplification utilized the DNA polymerase from Pyrococcus furiosus (Pfu) which, unlike Taq, does not incorporate a nontemplated terminal deoxyadenosine phosphate. An 89-base pair nucleotide portion of the spacer region between the 16S and 23S ribosomal rRNA genes was amplified from the genome of three members of Bacillus cereus group and a 114 nucleotide region from the Bacillus subtilis. PCR involves polymerization of nucleotide precursors using two oligonucleotide primers and an amplification enzyme, as well as the presence of metal ions. Mass spectrometric analysis greatly benefits from removal of the oligonucleotide primers (15- and 17-mers in this instance) and nucleotide precursors since they adversely affect sensitivity and metal ion adduction results in an inaccurate molecular weight determination. In the presence of guanidinium hydrochloride the PCR products bind preferentially to a silica resin, allowing removal of other components (i.e., dNTP's primers, and salts). Further removal of metal ions was accomplished using a microdialysis device, allowing samples to be pumped through a hollow cellulose fiber with external countercurrent flow of 2.5 mM ammonium acetate. Prior to injection into the mass spectrometer, the sample buffer was adjusted to 50 vol % acetronitrile, 25 mM piperidine, and 25 mM imidazole, which enhanced signal intensity. The molecular weights of the PCR products determined by nucleotide sequence and MS analysis were in excellent agreement, and several PCR products were analyzed where mass differences corresponding to single base substitutions could be accurately assigned. These assignments were possible due to the high mass precision, accuracy, and resolution FTICR inherently affords. This constitutes the first report demonstrating the ionization and detection of PCR products by mass spectrometry with mass precision and accuracy for assignment of such modifications or substitutions.

Bacillus↗
PubMed1996

Involvement of cytokines in lipopolysaccharide-induced facilitation of CGRP release from capsaicin-sensitive nerves in the trachea: studies with interleukin-1beta and tumor necrosis factor-alpha.

Lipopolysaccharide (LPS), an endotoxin, produces pain behavior, inflammation, and changes in immune function. Many of these effects are secondary to the production of cytokines. In the present study, we investigated the effect of LPS on the releasing function of afferent terminals as measured by calcitonin gene-related peptide (CGRP) release in ex vivo perfused rat trachea, and examined the possible role of the cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) as intermediaries in this effect. Systemic injection of LPS (0.75 mg/kg, i.p.) in adult rats induced an increase in body temperature followed by hypothermia, indicating ongoing infection. We observed that capsaicin-induced (0.1 microM) tracheal CGRP release was significantly enhanced in the LPS-treated animals after 5 hr. This enhancement of the peptide release by LPS was blocked by IL-1beta tripeptide antagonist Lys-D-Pro-Thr (10 microM) and mimicked by IL-1beta and TNF-alpha (10-100 pg/ml), suggesting that the potentiating effect of LPS on CGRP release is mediated by generation of IL-1beta and TNF-alpha. IL-1beta-induced augmentation of CGRP release was blocked by Lys-D-Pro-Thr. Additionally, the cyclooxygenase inhibitor ketorolac (10 microM) significantly attenuated the facilitatory effects of LPS and IL-1b, indicating involvement of prostanoids. These findings suggest that endotoxin treatment generated cytokines such as IL-1b and TNF-alpha that regulated the peripheral releasing function of primary sensory afferents by sensitizing the terminals and facilitating peptide release. This effect is prostanoid dependent.

Animals↗
PubMed1996

Peptides corresponding to CD4-interacting regions of murine MHC class II molecules modulate immune responses of CD4+ T lymphocytes in vitro and in vivo.

Immune responses mediated by CD4+ T cells depend on Ag-specific alpha beta TCRs that recognize the specific antigenic peptide presented by MHC class II molecules. Interactions between CD4 coreceptors and monomorphic regions of MHC class II molecules contribute to these responses. To examine whether immune reactions could be modulated by specifically interfering with CD4-MHC class II interactions, we have used, in various in vitro and in vivo assays, peptides that correspond to a region of MHC class II molecules previously shown to control interaction with CD4. Depending on the chemical nature and concentration of these peptides, they modulated Ag-specific responses of CD4+ T cells. At high concentrations, these peptides inhibited T cell responses in vitro. However, under conditions that can cause Ag-induced unresponsiveness, the peptides enhanced T cell responses. Also, primary in vivo immune responses to systemically administered soluble protein Ag, keyhole limpet hemocyanin, were enhanced when mice were treated with peptides corresponding to the CD4-interacting region of MHC class II molecules but not when treated with control peptides. Lymphokine profiles suggested that the peptides may favor the differentiation of Th1 cells, because lymphocytes from peptide-treated mice secreted more IL-2 and IFN-gamma than lymphocytes from nontreated or control-peptide-treated mice upon restimulation with Ag in vitro. These results demonstrate that MHC class II-derived peptides can directly interfere with interactions with CD4 and modulate T cell responses in vitro and in vivo.

Adjuvants, Immunologic↗
PubMed1996

Analysis of double-stranded polymerase chain reaction products from the Bacillus cereus group by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

The analysis of polymerase chain reaction (PCR) products by electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR) has been achieved. Specifically, a 105 base-pair nucleotide portion of the ribosomal spacer region was amplified in two members of the B. cereus group (i.e. B. thuringiensis and B. cereus) using PCR. These amplified regions were then analyzed by gel electrophoresis and ESI-FTICR. Based on the predicted sequence of the PCR products for each organism, the mass measurement using ESI-FTICR matched the theoretical mass within experimental error and was consistent with gel electrophoresis results. In contrast, for the typical several hour time-scale of the gel electrophoresis experiment, the mass spectrometric analysis was completed in a matter of minutes. To our knowledge, this constitutes the first report demonstrating the ionization and detection of a double-stranded PCR product by ESI-MS. This preliminary result indicates the potential use of ESI-MS to analyze PCR products on a rapid time-scale, with potential for medical and taxonomic applications.

Bacillus cereus↗
PubMed1996

Epidemiology of an outbreak due to glycopeptide-resistant Enterococcus faecium on a leukaemia unit.

The clinical and molecular epidemiology of two clusters of colonization and infection of patients by glycopeptide-resistant enterococci (GRE) on a leukaemia and bone marrow transplantation unit was studied over a two-and-a half-year period. Thirty-five patients became colonized, of whom six developed clinical infections. Of the 53 isolates of GRE, 49 were Enterococcus faecium, multiply-resistant to vancomycin and ampicillin. DNA fingerprinting of 48 E. faecium isolates by pulsed-field gel electrophoresis identified six DNA types. One strain of VanB phenotype E. faecium predominated during the initial outbreak, and an unrelated strain of the VanA phenotype was present in a second cluster. Environmental and patient isolates of E. faecium were indistinguishable by DNA typing. The VanA phenotype enterococci probably arose by transfer from the renal ward at a nearby hospital, and a patient with persistent diarrhoea may have contributed to contamination and cross-infection. GRE may cause significant infections in immunocompromised patients, and are readily transmitted between them. GRE were controlled, but not eradicated on the unit; infection control measures included improved environmental cleaning and modification of antibiotic use. In order to control GRE, it is necessary to educate healthcare workers and implement the traditional, effective values of good personal hygiene and environmental cleanliness.

Adult↗
PubMed1996

Moexipril versus captopril in patients with mild to moderate hypertension.

Moexipril is a new, long-acting angiotensin-converting enzyme (ACE) inhibitor. In contrast to captopril, it is a prodrug of the pharmacologically active agent moexiprilat and will be administered once daily. The objective of this study was to compare the efficacy, safety, and tolerability of moexipril with that of captopril during a 12-week treatment of patients with mild to moderate hypertension. Patients with a sitting diastolic blood pressure (SDBP) of 95-114 mm Hg, inclusive, were randomized in a 2:1 ratio to receive moexipril, 7.5 mg, once daily or captopril, 25 mg, twice daily. After 6 weeks of treatment, the dose of moexipril and captopril was increased to 15 mg once daily and 50 mg twice daily, respectively, if the patient's SDBP remained > or = 90 mm Hg. Blood pressure was measured at biweekly visits. At study endpoint, adjusted mean reductions in SDBP were comparable between the moexipril and captopril groups (-9.8 vs. -8.7 mm Hg), and moexipril was more effective than captopril in reducing sitting systolic blood pressure. Adverse experiences (headache, dizziness, and upper respiratory infection) occurred at similar frequencies in the moexipril and in the captopril groups. The data indicate that moexipril at dosages of 7.5 and 15 mg once daily is as efficacious as twice daily captopril in reducing blood pressure in patients with mild to moderate hypertension.

Adult↗
PubMed1996

Capsule phase variation in Neisseria meningitidis serogroup B by slipped-strand mispairing in the polysialyltransferase gene (siaD): correlation with bacterial invasion and the outbreak of meningococcal disease.

A mechanism of capsular polysaccharide phase variation in Neisseria meningitidis is described. Meningococcal cells of an encapsulated serogroup B strain were used in invasion assays. Only unencapsulated variants were found to enter epithelial cells. Analysis of one group of capsule-deficient variants indicated that the capsular polysaccharide was re-expressed at a frequency of 10(-3). Measurement of enzymatic activities involved in the biosynthesis of the alpha-2,8 polysialic acid capsule showed that polysialyltransferase (PST) activity was absent in these capsule-negative variants. Nucleotide sequence analysis of siaD revealed an insertion or a deletion of one cytidine residue within a run of (dC)7 residues at position 89, resulting in a frameshift and premature termination of translation. We analysed unencapsulated isolates from carriers and encapsulated case isolates collected during an outbreak of meningococcal disease. Further paired blood-culture isolates and unencapsulated nasopharyngeal isolates from patients with meningococcal meningitis were examined. In all unencapsulated strains analysed we found an insertion or deletion within the oligo-(dC) stretch within siaD, resulting in a frameshift and loss of capsule formation. All encapsulated isolates, however, had seven dC residues at this position, indicating a correlation between capsule phase variation and bacterial invasion and the outbreak of meningococcal disease.

Amino Acid Sequence↗
PubMed1996

Characteristics of rural homebound older adults: a community-based study.

OBJECTIVE: To determine the frequency and characteristics of homebound older adults in a rural community. DESIGN: An epidemiological survey of an age-stratified random community sample. SETTING: The rural mid-Monongahela Valley in Southwestern Pennsylvania. PARTICIPANTS: A total of 878 noninstitutionalized persons aged 68 years and older, fluent in English, and with at least grade 6 education. MEASUREMENTS: The frequency with which subjects left their homes, the Mini-Mental State Examination (MMSE) score, and additional information on demographics, self-reported health problems, health services utilization, IADLs, depression, and social support were measured. RESULTS: 10.3% of the sample was classified as homebound. In univariate analyses, being homebound was found to be associated significantly (P < .001) with being older, female, and widowed and with MMSE and IADL impairment, with more depressive symptoms and worse social supports, fair to poor self-rated general health, weight loss, and histories of stroke, angina, arthritis of the spine, and falls. In a multiple regression model, variables associated independently with homebound status were gender (odds ratio = 9.4, 95% confidence interval = 3.6 - 24.9), weight loss (OR = 3.7, CI = 1.7 - 8.2), IADL impairment (OR = 2.6, CI = 2.1 - 3.1), and depressive symptoms (OR = 2.1, CI = 1.3 - 3.2). Being homebound was also associated with recent acute hospitalization and use of home health and social services. CONCLUSIONS: These data provide evidence that homebound older adults have a disproportionate share of morbidity and disability and suggest a sociodemographic and clinical profile to help identify those older people at risk of being or becoming homebound. They also point to the need for home-based health services for the older adults, particularly in medically underserved communities such as rural areas.

Activities of Daily Living↗
PubMed1996

Absolute identification of muramic acid, at trace levels, in human septic synovial fluids in vivo and absence in aseptic fluids.

This is the first report of a study employing the state-of-the-art technique of gas chromatography-tandem mass spectrometry for absolute identification of muramic acid (a marker for peptidoglycan) at trace levels in a human or animal body fluid or tissue. Daughter mass spectra of synovial fluid muramic acid peaks (> or = 30 ng/ml) were identical to those of pure muramic acid. Absolute chemical identification at this level represents a 1,000-fold increase in sensitivity over previous gas chromatography-mass spectrometry identifications. Muramic acid was positively identified in synovial fluids during infection and was eliminated over time but was absent from aseptic fluids.

Arthritis, Infectious↗
PubMed1995

Do intracarotid barbiturate injections offer a way to investigate hemispheric models of anosognosia?

In a sample of 83 patients counterbalanced for side of temporal-lobe seizure focus, we examined unawareness of hemiplegia upon clearing of the deficit after bilateral sodium amobarbital injections. Unawareness occurred commonly (66%) and with equal frequency following left and right injections. These findings were not moderated by speech dominance, handedness, sex, or side of seizure focus. Unawareness occurred more frequently after injections contralateral to than ipsilateral to the major seizure focus and was related to objective memory performance after contralateral, but not after ipsilateral, injections. Unawareness of drug-induced hemiplegia was related to the functional status of the temporal lobe independently of hemispheric laterality or degree of frontal lobe inactivation as measured by filling of the anterior cerebral arteries.

Adolescent↗
PubMed1995

Antihypertensive effects of moexipril, a new ACE inhibitor, as add-on therapy to nifedipine in patients with essential hypertension.

Moexipril is a new nonpeptide angiotensin-converting enzyme (ACE) inhibitor with an intermediate duration of action. The antihypertensive efficacy and safety of moexipril as add-on therapy to nifedipine retard (20 mg b.i.d) was compared to placebo during 8 weeks in a double-blind trial with a parallel group design. A total of 203 patients with essential hypertension and a sitting diastolic blood pressure (DBP) > or = 95 mm Hg on nifedipine alone were randomly assigned to placebo or moexipril 3.75 mg o.d., 7.5 mg o.d., or 15 mg o.d.. At endpoint, the adjusted mean reductions in DBP from baseline were 6 mm Hg, 9 mm Hg (p < 0.01), and 9 mm Hg (p < 0.05) in the moexipril 3.75 mg, 7.5 mg, and 15 mg groups, respectively, compared to 5 mm Hg in the placebo group. All dosages of moexipril were well tolerated, and the overall percentages of patients who reported adverse experiences were smaller than in the placebo group. We concluded that moexipril as add-on therapy to nifedipine is well tolerated and gives additional antihypertensive effects.

Adolescent↗