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Biomedical subjects

A Fox

Publications and source records attributed to A Fox.

At least 19 recordsLinked to original sources
PubMed1998

Heterogeneity in Bacillus cereus PCR products detected by ESI-FTICR mass spectrometry.

PCR amplification of a segment of the 16/23S rDNA interspace region (ISR) from Bacillus cereus 6464 produced a mixture of products. An 89-bp product was predicted on the basis of the reported sequence. The ESI-FTICR analysis revealed three double-stranded products, differing in size by a single nucleotide corresponding to two homoduplexes of 89 and 88 base pairs and a heteroduplex of 89 and 88 nucleotide strands. These were produced from a single preparation of genomic DNA and a single primer pair. ESI-FTICR analysis of the single strands identified a deletion of a T in the coding strand and a corresponding loss of an A in the noncoding strand of this product. The ESI-FTICR analysis indicated the presence of an unreported sequence variation between rRNA operons in this organism. This report illustrates that PCR products amplified from templates differing by a single nucleotide can be resolved and identified using ESI-FTICR at the 89-bp level. Furthermore, the ESI-FTICR mass measurements provided the identity of the deletion, which is indicative of interoperon variability.

Bacillus cereus↗
PubMed1998

Preemptive treatment for the prevention of cytomegalovirus disease: in lung and heart transplant recipients.

BACKGROUND: Rapid quantifiable diagnostic techniques for the diagnosis of cytomegalovirus (CMV) infection may predict patients at risk of CMV pneumonitis and allow preemptive antiviral treatment. METHODS: Using CMV antigenemia as a prospective surveillance technique for CMV infection, we compared the outcome of preemptive treatment (PT) with ganciclovir, 10 mg/kg/day for 21 days directed by "high levels" of CMV antigenemia (PT group, n= 19), with the outcome in a group of historical controls (n=18) treated with ganciclovir when CMV illness occurred. Greater than 50 antigen-positive cells per 2 x 10(5) polymorphonuclear leukocytes was considered to be high-level antigenemia. RESULTS: Nine of the 18 controls developed high-level CMV antigenemia at a median of 33 days (range: 13-65 days) and 5 of the 9 developed CMV disease. Ten of the 19 PT group had high levels of CMV antigenemia detected at a median of 47 days (range: 20-63 days) and were given ganciclovir; none developed CMV disease. There was a significantly lower incidence of CMV disease in the PT group in comparison to controls (0 of 19 vs. 5 of 18: P=0.019). CONCLUSION: We have reduced the incidence of CMV disease using preemptive treatment, and because of a 100% negative predictive value, we omitted unnecessary antiviral prophylaxis for many at-risk patients.

Antibodies, Viral↗
PubMed1998

Morbidity of homebound versus inpatient elderly psychiatric patients.

This study compares the demographic and clinical characteristics of homebound (HB) elders referred for psychiatric services (N = 251) with those of inpatients (IP) admitted to a geriatric psychiatry unit (N = 594). Demographically, HB patients were older (78.8 vs 74.7 years), were more likely to be women (83% vs 68%), were widowed (54% vs. 44%), and had fewer years of education (10.3 vs. 11.1), but were similar in race, income, and proportion living alone. Clinically, HB patients had less functional disability, less severe depression, less cognitive impairment, and fewer medical problems. However, they were similar in the distribution of most psychiatric diagnoses except dementia (higher in the IP group) and dementia with depression (higher in the HB group). Outcome data for the HB group over 15 (range, 1 to 38) months revealed medical hospitalization in 20.7%, psychiatric hospitalization in 16.3%, nursing home placement in 9.2% and mortality in 8.4%. These preliminary data show that the HB group had psychiatric problems that were comparable to those of the IP group but were not as severely impaired.

Age Distribution↗
PubMed1998

Synthesis of microcapsule by Staphylococcus aureus is not responsive to environmental phosphate concentrations.

The polysaccharide microcapsule of Staphylococcus aureus has been reported to be differentially expressed depending on growth conditions, with phosphate concentration being the critical environmental component. This study evaluated the effect of growth of a serotype 8 strain of S. aureus in phosphate-replete and phosphate-limiting media on microcapsule production. The presence of the cell wall polymers microcapsule and teichoic acid was measured by both gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. Production of microcapsule was unaffected by changes in the environmental phosphate concentration. There was, additionally, no evidence for a shift from teichoic acid to teichuronic acid synthesis.

Bacterial Capsules↗
PubMed1997

Variations in the concentration of plutonium, strontium-90 and total alpha-emitters in human teeth collected within the British Isles.

Concentrations of plutonium-239, plutonium-240, strontium-90 and total alpha-emitters have been measured in children's teeth collected throughout Great Britain and Ireland. The concentrations of plutonium and strontium-90 were measured in batched samples, each containing approximately 50 teeth, using low-background radiochemical methods. The concentrations of total alpha-emitters were determined in single teeth using alpha-sensitive plastic track detectors. The results showed that the average concentrations of total alpha-emitters and strontium-90 were approximately one to three orders of magnitude greater than the equivalent concentrations of plutonium-239,240. Regression analyses indicated that the concentrations of plutonium, but not strontium-90 or total alpha-emitters, decreased with increasing distance from the Sellafield nuclear fuel reprocessing plant-suggesting that this plant is a source of plutonium contamination in the wider population of the British Isles. Nevertheless, the measured absolute concentrations of plutonium (mean = 5 +/- 4 mBq kg-1 ash wt.) were so low that they are considered to present an insignificant radiological hazard.

Adolescent↗
PubMed1997

Quantitative analysis of neutral and acidic sugars in whole bacterial cell hydrolysates using high-performance anion-exchange liquid chromatography-electrospray ionization tandem mass spectrometry.

A procedure for analysis of a mixture of neutral and acidic sugars in bacterial whole cell hydrolysates using high-performance anion-exchange liquid chromatography-electrospray ionization tandem mass spectrometry (HPAEC-ESI-MS-MS) is described. Certain bacteria (including bacilli), grown under phosphate-limited conditions, switch from producing a teichoic acid (containing ribitol) to a teichuronic acid (characterized by glucuronic acid content). Bacterial cells were hydrolyzed with sulfuric acid to release sugar monomers. The solution was neutralized by extraction with an organic base. Hydrophobic and cationic contaminants (including amino acids) were removed using C18 and SCX columns, respectively. HPAEC is well established as a high-resolution chromatographic technique, in conjunction with a pulsed amperometric detector. Alternatively, for more selective detection, sugars (as M-H- ions) were monitored using ESI-MS. In HPAEC, the mobile phase contains sodium hydroxide and sodium acetate, which are necessary for chromatographic separation of mixtures of neutral and acidic sugars. Elimination of this high ionic content prior to entry into the ESI ion source is vital to avoid compromising sensitivity. This was accomplished using an on-line suppressor and decreasing post-column flow-rates from 1 ml to 50 microliters/min. In the selected ion monitoring mode, background (from the complex sample matrix as well as the mobile phase) was eliminated, simplifying chromatograms. Sugar identification was achieved by MS-MS using collision-induced dissociation.

Bacillus subtilis↗
PubMed1997

Molecular epidemiology of glycopeptide-resistant Enterococcus faecium on a renal unit.

The clinical and molecular epidemiology of glycopeptide-resistant Enterococcus faecium was investigated during an outbreak on a renal unit. Forty-nine patients were colonized or infected during a 15-month period. Sites of colonization included faeces, urine, intravenous (IV) catheter tips and wound swabs. Ten patients had infections, which included five bacteraemias and three episodes of peritonitis. Pulsed-field gel electrophoresis of 43 patient isolates of glycopeptide-resistant E. faecium identified seven strains during the first 7 months of the outbreak. Three of these strains affected five or more patients. One strain accounted for 17/43 isolates. Isolates that were possibly related to another renal unit strain were cultured from patients at two other Manchester hospitals. These isolates were epidemiologically-related, and may represent a single Manchester epidemic strain. Of five patients who had multiple isolates of glycopeptide-resistant E. faecium, three had isolates representing a single strain and two were colonized or infected by more than one strain.

Adult↗
PubMed1997

Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-d-old domestic chicks.

1. To examine the effects of beak trimming on behaviour, beak anatomy, weight gain, food intake and feather condition 360 ISA Brown chicks were trimmed by hot cut or cold cut at 1 d or 10 d of age or were sham-operated controls. The experiment was a 3 x 2 factorial design, with the chicks housed in littered pens in groups of 10 and observed for 6 weeks after trimming. 2. In the first week after trimming, when trimmed birds were compared with untrimmed controls, they were less active (sat and slept more), fed less, preened less and generally engaged in less beak-related behaviour. 3. These differences waned sharply during week 2 and had disappeared by week 5. There were very few differences between hot- and cold-cut birds. 4. There were also differences in production variables: trimmed birds grew more slowly during the week after trimming, their food intake was depressed for 3 weeks and food conversion efficiency improved for 2 weeks. 5. The only significant effect on feather scores was better plumage condition in the groups trimmed at 1 d and scored at 6 weeks. 6. To examine the anatomical effects 36 ISA Brown chicks trimmed by hot or cold cut at 1 d or 10 d of age were killed at 21 and 42 d after trimming, and their beaks were processed and examined histologically. In all trimmed groups healing was very rapid and no scar tissue was seen but, unlike the controls, the regrown tips contained no afferent nerves or sensory corpuscles. 7. Beak lengths immediately after trimming were 40% to 50% shorter than controls; the anatomical consequences of both methods were identical. 8. Overall, it was judged that the effects on behaviour and beak anatomy were much less severe than previously reported for birds trimmed at older ages. If birds do have to be trimmed then the procedure should be carried out in young birds: from the birds' standpoint 1 d appears to be the most suitable.

Aggression↗
PubMed1997

Penetrating esophageal injuries: time interval of safety for preoperative evaluation--how long is safe?

OBJECTIVES: This study was performed to assess the experience with penetrating esophageal injuries of an urban Level I trauma center and to attempt to correlate the time to establish a diagnosis with outcome including death, surgical intensive care unit length of stay, and esophageal-related complications. METHODS: Retrospective study over a 72-month period at a single institution comparing age, admission blood pressure, Revised Trauma Score (RTS), Injury Severity Score (ISS), mechanism and anatomic location of injury, and time interval from admission to the operating room (OR) between nonsurvivors and survivors. Patients who survived to reach the operating room were divided into two groups: those who went immediately to the operating room (no preoperative evaluation) and those who underwent diagnostic studies to identify their injuries (preoperative evaluation). Data analysis was done of the same parameters plus average number of associated injuries, complications, and intensive care unit length of stay. Statistical methods used univariate analysis (Fisher's exact test and Student's t test). RESULTS: Forty-three patients were identified with penetrating esophageal injuries and had the following characteristics: 36 males (84%) and 7 females (16%); mean RTS, 9.39; mean ISS, 28.1; mean time interval to OR, 9.8 hours. Associated injuries occurred with 42 patients (98%). The overall complication rate was 14 of 32 (44%), and the overall mortality was 11 of 43 (26%). Corrected mortality was 22%. Differences were noted between nonsurvivors and survivors in the following parameters: admission blood pressure < 90, 11 of 11 versus 3 of 29 (p < 0.001); RTS, 2.364 versus 11.406 (p < 0.001); ISS, 45 versus 21 (p < 0.001); time interval from admission to OR, 18.3 minutes versus 9.8 hours (p < 0.05). Thirty-six patients survived to reach the operating room, 18 in the no preoperative evaluation group and 17 in the preoperative evaluation group. No statistically significant differences were noted between these two groups in the following parameters: age, RTS, ISS, admission blood pressure, anatomic location of injury, number of associated injuries, or intensive care unit length of stay. Average length of time to the operating room was 16.7 hours in the preoperative evaluation group and 1.4 hours in the no preoperative evaluation group (p < 0.001). Twelve complications (all esophageal-related) occurred among seven patients in the preoperative evaluation group, and seven complications (five esophageal-related) occurred among seven patients in the no preoperative evaluation group. Because of the small sample size, this failed to reach a statistical difference (p < 0.05). CONCLUSIONS: Esophageal injuries carry a high morbidity and mortality. Although no definite conclusion can be drawn because of the small sample size, there does appear to be an increased morbidity associated with the diagnostic workup and its inherent delay in operative repair of these injuries. For centers practicing selective management of penetrating neck injuries and transmediastinal gunshot wounds, the rapid diagnosis and definitive repair of esophageal injury should be made a high priority.

Adult↗
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↗