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Biomedical subjects

A Miller

Publications and source records attributed to A Miller.

At least 127 records · Page 7Linked to original sources
PubMed1999

Protein disulfide isomerase catalyzes the formation of disulfide-linked complexes of vitronectin with thrombin-antithrombin.

In this study, purified preparations of platelet protein disulfide isomerase (PDI), vitronectin, alpha-thrombin, and antithrombin (AT) were used to demonstrate that PDI catalyzes formation of vitronectin-thrombin-AT complexes. Complex formation requires reduced glutathione (GSH) and can be prevented by N-ethymaleimide, and the formed complex is dissociated by reducing agents such as mercaptoethanol. No vitronectin-thrombin complex formed in the absence of AT, indicating that the thrombin-AT complex is an obligate intermediate in the reaction. Under optimal conditions, the majority of the thrombin-AT is incorporated into the complex in 60 min. Thrombospondin-1, known to form disulfide-linked complexes with thrombin-AT [Milev, Y., and Essex, D. W. (1999) Arch. Biochem. Biophys. 361, 120-126], competes with vitronectin for thrombin-AT in the low-Ca(2+) environment that favors the active form of thrombospondin. The results presented here may also explain previous studies showing that vitronectin-thrombin-AT complexes form better in plasma (which contains PDI) than with purified proteins (where PDI was not used). We were able to purify a PDI from plasma that was immunologically identical to the platelet enzyme. We used the scrambled RNase assay to show that added purified PDI can function in a plasma environment. Complex formation in plasma was inhibited by inhibitors of PDI. PDI was released from the platelet surface in a soluble form at high pH (around the physiologic range), suggesting a source of the plasma PDI. In summary, these studies indicate that PDI functions to form disulfide-linked complexes of vitronectin with thrombin-AT.

Animals↗
PubMed1999

Changes in oxygenation during radiotherapy in carcinoma of the cervix.

PURPOSE: The aim of this study was to investigate changes in tumor oxygenation, assessed by polarographic needle electrode measurements, following fractionated external beam radiotherapy in carcinoma of the cervix. METHODS AND MATERIALS: Normal and tumor tissue oxygenation was measured in 19 patients prior to radiotherapy and after 40-45 Gy of external beam radiotherapy delivered in 20 fractions over 4 weeks. All measurements were performed during anesthesia. RESULTS: There was no significant difference in the level of normal tissue oxygenation pre- and post radiotherapy. The individual patient median tumor pO2 values ranged from 0 to 31 mmHg pre-radiotherapy and 1 to 61 mmHg post-radiotherapy. The mean of the 19 median pO2 values increased from 8 (SD +/- 10) mmHg to 20 (+/- 20) mmHg following external beam radiotherapy. The increase was significant by paired Wilcoxon test (p = 0.011). There was also a significant fall in the proportion of values < 5 mmHg (p = 0.040). Although this value remained constant, or fell, in the majority of patients (15/19), it increased in 4 tumors. Tumor size pre- and postradiotherapy did not correlate with the level of pretreatment oxygenation; neither did the change in tumor size and change in level of oxygenation. CONCLUSION: The level of tumor oxygenation increased in the majority of patients (15/19) following 40-45 Gy of radiotherapy in carcinoma of the cervix.

Adult↗
PubMed1999

Implementing effectiveness research and improving care for schizophrenia in real-world settings.

OBJECTIVE: To review recent advances in medication practices and standards of care in the treatment of schizophrenia and examine the disparity between the knowledge base and clinical practice. DATA SOURCES: Key literature on medication practices, novel pharmacotherapies, and the evolution of practice guidelines for schizophrenia were reviewed. DISCUSSION: Emerging data demonstrate a lack of consistent application of current knowledge and best practices, in part due to major structural inconsistencies in the public mental health system. Implementation of results from effectiveness research as well as the incorporation of practice guidelines may help bridge this gap. CONCLUSION: As standards of care for schizophrenia are developed, the following issues will need particular attention: coordination with the criminal justice system, comprehensive treatment of comorbid illnesses, outcomes based on symptoms in all domains, and continuous and integrated collection of data to produce rational cost justification.

Antipsychotic Agents↗
PubMed1999

Mutagenesis studies of the FeSII protein of Azotobacter vinelandii: roles of histidine and lysine residues in the protection of nitrogenase from oxygen damage.

The Azotobacter FeSII protein, also known as the Shethna protein, forms a protective complex with nitrogenase during periods when nitrogenase is exposed to oxygen. One possible mechanism for its action is an oxidation state-dependent conformational interaction with nitrogenase whereby the FeSII protein dissociates from the MoFe and Fe proteins of nitrogenase under reducing conditions. Herein we report the construction and characterization of five site-directed mutants of the FeSII protein (H12Q, H55Q, K14A, K15A, and the double mutant K14A/K15A) which were individually purified after being individually overexpressed in Escherichia coli. These mutant FeSII proteins maintain native-like assembly and orientation of the 2Fe-2S center on the basis of EPR and NMR spectroscopic characterization and their redox midpoint potentials, which are within 25 mV of that of the wild type protein. The abilities of the individual mutant proteins to protect nitrogenase were assessed by determining the remaining nitrogenase activities after adding each pure version back to extracts from an FeSII deletion strain, and then exposing the mixture to oxygen. In these assays, the H12Q mutant functioned as well as the wild type protein. However, mutation of His55, a few residues away from a cluster-liganding cysteine, results in much less efficient protection of nitrogenase. These results are consistent with pH titrations in both oxidation states, which show that His12 is insensitive to 2Fe-2S cluster oxidation state. His55's pK is weakly responsive to oxidation state, and the pK increase of 0. 16 pH unit upon 2Fe-2S cluster oxidation is indicative of ionization of another group between His55 and the 2Fe-2S cluster, which could modulate the FeSII protein's affinity for nitrogenase in a redox state-dependent manner. Both K14A and K15A mutant FeSII proteins partially lost their ability to protect nitrogenase, but the lysine double mutant lost almost all its protective ability. The nitrogenase component proteins in an Azotobacter strain bearing the double lysine mutation (in the chromosome) were degraded much more rapidly in vivo than those in the wild type strain under carbon substrate-limited conditions. These results indicate that the two lysines may have an important role in FeSII function, perhaps in the initial steps of recognizing the nitrogenase component proteins.

Azotobacter vinelandii↗
PubMed1999

Infectious complications related to the use of the angio-seal hemostatic puncture closure device.

One hundred and eight coronary angiography procedures in which the Angio-Seal device was utilized were complicated by eight (7.4%) hematomas, of which two (1.9%) subsequently developed infection (Staphylococcus aureus endarteritis and S. aureus septic hematoma). The Angio-Seal device may be a risk factor for infection for two reasons: excessive hematoma formation (a known risk factor for endarteritis), and foreign material remaining within the arterial lumen and wall, thereby creating a nidus for infection.

Adult↗
PubMed1999

Older patients' health-related quality of life around an episode of emergency illness.

STUDY OBJECTIVES: We sought to describe older patients' health-related quality of life during a 4-month period surrounding a visit to the emergency department and to identify factors associated with less recovery. METHODS: We prospectively studied 983 patients 65 years or older who presented to an urban academic ED in 1995 and 1996. Eighty percent of the patients were African American, and 63% were women. The primary outcome measures were the Katz Index of Activities of Daily Living and revised validated questions from the Medical Outcomes Study Health Survey at 1 month before the ED visit, the time of the ED visit, and 2-week and 3-month follow-up periods. RESULTS: In general, patients worsened markedly during the illness and then improved, although not to baseline levels. After adjustment for demographic and social factors, the most consistently powerful predictors of poor recovery were more deficiencies in activities of daily living at baseline, reports of needing more help with everyday tasks, increasing Charlson Comorbidity Index scores, and requiring a proxy for the initial survey. CONCLUSION: Emergency physicians and primary care physicians should consider inquiring about functional status and the adequacy of help at home in addition to comorbid conditions for their acutely ill older patients to target those at greatest risk for poor recovery. Future work needs to test interventions that may improve the health-related quality of life of these vulnerable patients.

Activities of Daily Living↗
PubMed1999

Microinjection of cyclic ADP-ribose triggers a regenerative wave of Ca2+ release and exocytosis of cortical alveoli in medaka eggs.

Medaka (Oryzias latipes) eggs microinjected with the Ca(2+)-mobilising messenger cyclic adenosine diphosphate ribose (cADPR) underwent a wave of exocytosis of cortical alveoli and were thus activated. The number of eggs activated was sharply dependent on the concentration of cADPR in the pipette, the threshold concentration was approximately 60 nM. After injection, a pronounced latency preceded the onset of cortical alveoli exocytosis; this latency was independent of the concentration of cADPR but decreased markedly with increasing temperature. Heat-treated cADPR, which yields the inert non-cyclised product ADP-ribose, was ineffective in activating eggs. When cADPR was injected into aequorin-loaded eggs, a wave of luminescence arose at the site of cADPR injection and then swept out across the egg with a mean velocity of approximately 13 microns/s; the velocity was independent of the concentration of injected cADPR. In such a large cell (diameter of around 1 mm), this is considerably faster than that possible by simple diffusion of cADPR, which unambiguously demonstrates that cADPR must activate a regenerative process. cADPR has been demonstrated to modulate Ca(2+)-induced Ca2+ release (CICR) via ryanodine receptors (RyRs) in many cell types, and consistent with this was the finding that microinjection of the pharmacological RyR modulator, ryanodine, also activated medaka eggs. These results suggest that a cADPR-sensitive Ca2+ release mechanism is present in the medaka egg, that cADPR is the most potent activator of medaka eggs described to date, and that it activates eggs by triggering a wave of CICR from internal stores that in turn stimulates a wave of exocytosis.

Adenosine Diphosphate Ribose↗
PubMed1999

High-dose paclitaxel plus G-CSF for malignant mesothelioma: CALGB phase II study 9234.

BACKGROUND: New agents with activity in mesothelioma are sorely needed. The Cancer and Leukemia Group B (CALGB) therefore performed a phase II study of high-dose paclitaxel in patients with malignant mesothelioma who had no prior chemotherapy. PATIENTS AND METHODS: Thirty-five patients accrued to this multi-institutional phase II study of paclitaxel given as a 24-hour infusion at 250 mg/m2 every three weeks plus filgrastim (G-CSF) 300 mcg subcutaneously days 3-18. RESULTS: There were three (9%) regressions of evaluable disease. The median survival was five months (95% confidence interval (95% CI): 1.9-9.6 months), the one-year survival rate was 14% and the two-year survival rate was 6%. Toxicity was tolerable with one death from pneumonia (without neutropenia) on day 18 and a 23% rate of grade 4 granulocytopenia. CONCLUSIONS: The level of activity seen with paclitaxel is similar to that seen in other CALGB trials of the single agents carboplatin, trimetrexate and 5-azacytidine. Future studies of of paclitaxel (at lower doses) in combination with synergistic agents could be considered.

Adult↗
PubMed1999

The effect of alcohol abuse on the health status of older adults seen in the emergency department.

OBJECTIVE: To examine the effect of alcohol abuse on the subsequent health status of elderly patients seen in an emergency department (ED). PATIENTS AND METHODS: A sample of 966 patients aged 65 or older who presented to one urban academic ED between the hours of 8 A.M. and 12 midnight was followed for 1 year. A personal interview was administered during the ED visit. Current problem drinkers had a score of 1 or greater on the CAGE questionnaire at ED presentation and drank within the prior 6 months; former problem drinkers had a score of 1 or greater on the CAGE questionnaire at ED presentation and a last drink more than 6 months previously. We used 13 items from the Medical Outcomes Study short form adapted to the ED setting and 6 items from the Index of Activities of Daily Living (ADL) to measure health status. RESULTS: In multivariate models for repeated-measures controlling for potential confounding factors, current problem drinkers had worse overall health (parameter estimate beta -3.6; 95% CI -7.1 to -0.04), and former problem drinkers had worse mental health (beta -3.6; CI -6.9 to -0.24) on follow-up. We could find no effect of problem drinking on physical health or social function. CONCLUSIONS: Current problem drinking is associated with worse self-perceived health among elderly patients in the year following presentation to an ED. The magnitude of decline in health perception may approximate the effect of having back pain, sciatica, or other musculoskeletal complaints. Elderly former problem drinkers suffer from more severe mental health problems over that same period.

Activities of Daily Living↗
PubMed1999

Anti-transglutaminase antibodies and coeliac disease.

BACKGROUND: Anti-endomysial antibodies have high specificity for coeliac disease but measurements are limited by the requirement for monkey oesophagus, a substrate that is expensive, and of limited availability and ethical acceptance. Tissue transglutaminase has recently been identified as the endomysial autoantigen in coeliac disease. AIMS: To examine the validity of serum tissue transglutaminase antibody levels in patients with coeliac disease and to assess their sensitivity and specificity against standard serological tests. METHODS: Serum IgA anti-tissue transglutaminase antibody titres (measured by ELISA), IgA anti-gliadin antibody titres (measured by a commercial ELISA) and anti-endomysial antibody titres (measured by indirect immunofluorescence) were determined in 46 untreated and 14 treated patients biopsy-proven coeliac disease and 145 disease and healthy controls. RESULTS: All patients with untreated coeliac disease were positive for anti-endomysial and anti-tissue transglutaminase antibodies (sensitivity 100%). Seventy-one per cent of treated coeliac patients were anti-tissue transglutaminase antibody negative. Five of 145 disease and healthy controls had low titres of anti-tissue transglutaminase antibody (specificity 97%); no controls were anti-endomysial antibody positive. CONCLUSIONS: Our results demonstrated the sensitivity and specificity of IgA anti-tissue transglutaminase antibodies to correlate highly with anti-endomysial antibodies in the diagnosis of coeliac disease. The ELISA for IgA anti-tissue transglutaminase antibodies is quantitative and easy to perform and is a valid alternative to indirect immunofluorescence for anti-endomysial antibodies in screening for suspected coeliac disease.

Antibodies↗
PubMed1999

Appropriateness of medication selection for older persons in an urban academic emergency department.

OBJECTIVES: To determine the frequency of potentially inappropriate medication selection for older persons presenting to the ED, the most common problematic drugs, risk factors for suboptimal medication selection, and whether use of these medications is associated with worse outcomes. METHODS: The authors performed a prospective cohort study of 898 patients 65 years or older who presented to an urban academic ED in 1995 and 1996. Seventy-nine percent of the patients were African-American and 43% did not graduate from high school. Potentially inappropriate medications and adverse drug-disease interactions were identified using the 1997 Beers explicit criteria for elders. During the three months after the initial visit, revisits to the ED or hospital, death, and changes in health-related quality of life were analyzed as measured by validated questions adapted from the Medical Outcomes Study. RESULTS: Upon presentation, 10.6% of the patients were taking a potentially inappropriate medication, 3.6% were given one in the ED, and 5.6% were prescribed one upon discharge from the ED. The most frequently prescribed potentially inappropriate medications in the ED were diphenhydramine, indomethacin, meperidine, and cyclobenzaprine. Emergency physicians added potentially inappropriate medications most often to patients with discharge diagnoses of musculoskeletal disorder, back pain, gout, and allergy or urticaria. Potentially adverse drug-disease interactions were relatively uncommon at presentation (5.2%), in the ED (0.6%), and on discharge from the ED (1.2%). Potentially inappropriate medications and adverse drug-disease interactions prescribed in the ED were not associated with higher rates of revisit to the ED, hospitalization, or death, but were correlated with worse physical function and pain. However, confidence intervals were wide for analyses of revisits and death. CONCLUSIONS: Suboptimal medication selection was fairly common and was associated with worse patient-reported health-related quality of life.

Accidental Falls↗
PubMed1999

Cloning, molecular analysis, and expression of the polyhydroxyalkanoic acid synthase (phaC) gene from Chromobacterium violaceum.

The polyhydroxyalkanoic acid synthase gene from Chromobacterium violaceum (phaC(Cv)) was cloned and characterized. A 6.3-kb BamHI fragment was found to contain both phaC(Cv) and the polyhydroxyalkanoic acid (PHA)-specific 3-ketothiolase (phaA(Cv)). Escherichia coli strains harboring this fragment produced significant levels of PHA synthase and 3-ketothiolase, as judged by their activities. While C. violaceum accumulated poly(3-hydroxybutyrate) or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) when grown on a fatty acid carbon source, Klebsiella aerogenes and Ralstonia eutropha (formerly Alcaligenes eutrophus), harboring phaC(Cv), accumulated the above-mentioned polymers and, additionally, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) when even-chain-length fatty acids were utilized as the carbon source. This finding suggests that the metabolic environments of these organisms are sufficiently different to alter the product range of the C. violaceum PHA synthase. Neither recombinant E. coli nor recombinant Pseudomonas putida harboring phaC(Cv) accumulated significant levels of PHA. Sequence analysis of the phaC(Cv) product shows homology with several PHA synthases, most notably a 48% identity with that of Alcaligenes latus (GenBank accession no. AAD10274).

Acyltransferases↗
PubMed1999

Two new early bacteriophage T4 genes, repEA and repEB, that are important for DNA replication initiated from origin E.

Two new, small, early bacteriophage T4 genes, repEA and repEB, located within the origin E (oriE) region of T4 DNA replication, affect functioning of this origin. An important and unusual property of the oriE region is that it is transcribed at early and late periods after infection, but in opposite directions (from complementary DNA strands). The early transcripts are mRNAs for RepEA and RepEB proteins, and they can serve as primers for leading-strand DNA synthesis. The late transcripts, which are genuine antisense RNAs for the early transcripts, direct synthesis of virion components. Because the T4 genome contains several origins, and because recombination can bypass a primase requirement for retrograde synthesis, neither defects in a single origin nor primase deficiencies are lethal in T4 (Mosig et al., FEMS Microbiol. Rev. 17:83-98, 1995). Therefore, repEA and repEB were expected and found to be important for T4 DNA replication only when activities of other origins were reduced. To investigate the in vivo roles of the two repE genes, we constructed nonsense mutations in each of them and combined them with the motA mutation sip1 that greatly reduces initiation from other origins. As expected, T4 DNA synthesis and progeny production were severely reduced in the double mutants as compared with the single motA mutant, but early transcription of oriE was reduced neither in the motA nor in the repE mutants. Moreover, residual DNA replication and growth of the double mutants were different at different temperatures, suggesting different functions for repEA and repEB. We surmise that the different structures and protein requirements for functioning of the different origins enhance the flexibility of T4 to adapt to varied growth conditions, and we expect that different origins in other organisms with multiorigin chromosomes might differ in structure and function for similar reasons.

Amino Acid Sequence↗
PubMed1999

Exacerbation of bleomycin-induced lung injury in mice by amifostine.

Bleomycin (BLM) induces lung injury and fibrosis in the murine lung and enhances tumor necrosis factor (TNF)-alpha and collagen mRNA expression in the murine lung. Amifostine is a cytoprotective agent that protects normal tissues from the cytotoxic effects of chemo- and radiation therapy. We investigated the effect of amifostine in BLM-induced lung injury in mice. Mice received intraperitoneal amifostine (200 mg/kg) 30 min before and/or 1, 3, and 7 days after an intratracheal injection of saline or BLM (4 U/kg). The animals were killed 14 days after BLM exposure, and their lungs were studied for TNF-alpha and collagen mRNA expression, hydroxyproline content, and histopathology. Light microscopy demonstrated that amifostine exacerbated the BLM-induced lung injury in mice. Increased TNF-alpha mRNA expression as a result of BLM exposure was not modulated by amifostine treatment. In contrast, amifostine treatment enhanced the BLM-induced expression of alpha(1)(I) procollagen mRNA in the lung. Similarly, mice treated with amifostine before BLM exposure accumulated significantly higher amounts of hydroxyproline (111 +/- 5 microg/lung) than BLM-treated animals (90 +/- 6 microg/lung). These data suggest that amifostine treatment exacerbates BLM-induced lung injury in mice.

Amifostine↗
PubMed1999

Attention-deficit hyperactivity disorder in children and youth: a quantitative systematic review of the efficacy of different management strategies.

OBJECTIVE: To obtain estimates of the relative efficacy of 3 main treatment strategies for attention-deficit hyperactivity disorder (ADHD) in children and youth (age < 18 years). METHODS DESIGN: quantitative systematic review of randomized trials. SUBJECTS: 999 patients with ADHD from 26 randomized trials. INTERVENTIONS: medications alone, behavioural interventions alone, and a combination of these 2 modalities. MAIN OUTCOME MEASURE: differences in scores between treatment groups on commonly used teacher- and parent-completed behaviour rating scales. RESULTS: Medication-only therapy was efficacious in ADHD. Behavioural therapies used alone appeared not to be efficacious in ADHD. Combination therapy was more efficacious than placebo or no treatment for parent but not teacher ratings, not more efficacious than drug therapy alone, and more efficacious than behavioural treatments alone based on parent but not teacher ratings. CONCLUSION: Though stimulant medications were found to be an effective treatment strategy for ADHD in children and youth, it proved difficult to assess the relative benefits of behavioural interventions alone and combined medication and behavioural therapy because of the paucity of treatment studies other than medication-only treatment studies and heterogeneity of various kinds that exist in relation to ADHD studies and treatments.

Adolescent↗