Biomedical subjects

H Miller

Publications and source records attributed to H Miller.

At least 73 records · Page 4Linked to original sources

PubMed1995

An L40C mutation converts the cysteine-sulfenic acid redox center in enterococcal NADH peroxidase to a disulfide.

Multiple sequence alignments including the enterococcal NADH peroxidase and NADH oxidase indicate that residues Ser38 and Cys42 align with the two cysteines of the redox-active disulfides found in glutathione reductase (GR), lipoamide dehydrogenase, mercuric reductase, and trypanothione reductase. In order to evaluate those structural determinants involved in the selection of the cysteine-sulfenic acid (Cys-SOH) redox centers found in the two peroxide reductases and the redox-active disulfides present in the GR class of disulfide reductases, NADH peroxidase residues Ser38, Phe39, Leu40, and Ser41 have been individually replaced with Cys. Both the F39C and L40C mutant peroxidases yield active-site disulfides involving the new Cys and the native Cys42; formation of the Cys39-Cys42 disulfide, however, precludes binding of the FAD coenzyme. In contrast, the L40C mutant contains tightly-bound FAD and has been analyzed by both kinetic and spectroscopic approaches. In addition, the L40C and S41C mutant structures have been determined at 2.1 and 2.0 A resolution, respectively, by X-ray crystallography. Formation of the Cys40-Cys42 disulfide bond requires a movement of Cys42-SG to a new position 5.9 A from the flavin-C(4a) position; this is consistent with the inability of the new disulfide to function as a redox center in concert with the flavin. Stereochemical constraints prohibit formation of the Cys41-Cys42 disulfide in the latter mutant.

Amino Acid Sequence↗

PubMed1995

Establishing benchmarks for ambulatory surgery costs.

The acceleration of managed care activity has made benchmark data on performance especially important. To date, benchmark data on financial and clinical performance in ambulatory surgery have been lacking in both hospital-based and independent, freestanding ambulatory surgery centers. This article discusses tools, empirical data, and strategies to assist financial (and clinical) managers in healthcare organizations critically examine the efficiency of their ambulatory surgery services.

Ambulatory Surgical Procedures↗

PubMed1995

A phase II study of menogaril (7R-O-methylnogarol) in patients with relapsed/refractory acute myeloid leukemia: a study of the Eastern Cooperative Oncology Group.

Fifty-one patients (47 evaluable) with AML, 27 in first relapse and 20 either in second relapse or refractory were treated with menogaril, 100 mg/m2/day as a 90-min infusion daily for 5 days. The complete response (CR) rate was 17% (8/47), and there was one partial response. Seven of eight responders were in first relapse with a 26% response rate among first relapse patients (7/27). The median duration of survival was 3 months for all first relapse patients and 4.3 months for all other patients. Toxicity included grades 3-4 pancytopenia and fever (100% of patients) and grades 3-4 stomatitis and hepatic enzyme elevation (25% of patients). Grades 3-4 cardiac toxicity occurred in three patients (two grade 3 arrhythmias and one heart block). All had previously received anthracyclines. Remission duration was 1.6-48+ months; two patients underwent bone marrow transplantation and continue in CR at 36+ and 48+ months. The nontransplanted patients remained in CR 1.6, 2.0, 3, 7, 14 and 27 months. Activity and toxicity of menogaril in this study were comparable to that of other clinically useful anthracyclines in AML. Further investigation of this agent in AML is warranted.

Acute Disease↗

PubMed1994

Identification of a 3'-->5'-exonuclease that removes cytosine arabinoside monophosphate from 3' termini of DNA.

Cytosine arabinoside monophosphate (araCMP) at the 3' terminus of DNA constitutes a lesion that impedes further synthesis by DNA polymerase alpha (DNA pol alpha). A biochemical assay has been designed to detect 3'-->5'-exonucleases in cell extracts that remove the 3'-araCMP lesion in an oligonucleotide template-primer and permit subsequent extension by DNA pol alpha. The major 3'-->5'-exonuclease activity in human myeloblast extracts has been purified, and gel filtration chromatography of the purified enzyme indicates that the exonuclease has an apparent native molecular mass of 52 kDa. Incubation of the enzyme with a 5'-32P-labeled araCMP template-primer results in exonucleolytic degradation of the primer exclusively in the 3'-->5' direction, demonstrating that the enzyme is a 3'-->5'-exonuclease. The products of the 3'-->5'-exonuclease reaction are 5'-mononucleotides. The apparent rate of araCMP removal by the exonuclease is approximately the same as the rate of deoxynucleoside monophosphate (dNMP) removal. Furthermore, the apparent rates of 3'-terminal excision are approximately the same whether the oligomer is hybridized to a complementary oligonucleotide, or not, indicating that the enzyme has both single- and double-stranded 3'-->5'-exonuclease activity. The enzyme does not possess 5'-->3'-exonuclease activity, nor is it associated with DNA polymerase activity. In addition, the enzyme does not cleave 3'-phosphoryl-terminated DNA, and it does not cleave RNA. The enzymatic characteristics of the isolated 3'-->5'-exonuclease indicate that it is distinct from previously identified mammalian deoxyribonucleases.

Arabinonucleotides↗

PubMed1994

Improvements to the differential display method for gene analysis.

Differential display requires two primers to identify discordantly expressed mRNAs. Anchored primers with at least one G residue were superior to those which had one C residue and those ending in A or T were the least efficient. Arbitrary primers with GC pairs at the 5'end were superior to primers with GC pairs at the 3'end. We found that screening of amplified DNA-fixed membranes by a slot blot manifold and hybridization with DNA probes made from sample RNA rapidly re-screened with DNA fragments for differential expression, requires less RNA and is faster than Northern analysis. Similarly, hybridization of DNA fragments to plasmid DNA fixed to membranes and direct PCR sequencing rapidly determine homology to common laboratory plasmids prior to any further manipulation. These modifications permit rapid isolation and characterization of DNA fragments identified by differential display.

Animals↗

PubMed1994

An evaluation of laparoscopic versus open cholecystectomy.

OBJECTIVE: To compare open cholecystectomy (OC) with laparoscopic cholecystectomy (LC) in terms of clinical aspects and a limited review of costs. SETTING: The Austin Hospital, Melbourne, a university teaching hospital. DESIGN: Prospective LC patients were compared with a retrospective group of OC patients whose surgery had been performed by the same surgeons. METHODS: Consecutive patients undergoing LC were interviewed, their medical records were analysed and the cost of their hospitalisation was assessed. Similar data, collected previously from patients undergoing OC, were used for comparison. RESULTS: There were 108 patients in each group, 93.5% treated electively. All had gallstones. No deaths or common bile duct injury occurred. The mean operating room time was 131 +/- 3.7 minutes for OC and 164 +/- 4.7 minutes for LC. Operative cholangiography was attempted in 80% in each group, being successful when attempted in all OCs and in 95% of LCs. The conversion rate of LCs to OCs was 4.5%. Minor complications were more frequent with OCs. The mean duration of hospital stay was 6.5 +/- 0.3 days for OCs and 2.0 +/- 0.2 days for LCs. The amount and period of analgesia were significantly less in the LC group. Patients recovered significantly faster after LC (P < 0.01) during the first eight weeks after surgery. There was no difference by 12 weeks. The overall cost for each LC was $838 less than OC for the entire hospital stay. CONCLUSION: These results support the view that LC is a safe and justified replacement for OC in the elective situation, with benefits to the patient, hospital and general community. The hospital cost for LC was less than for OC.

Adolescent↗

PubMed1994

Ontogeny of glycoprotein gB-specific antibody and neutralizing activity during natural cytomegalovirus infection.

The envelope glycoprotein gB (gpUL55) is a candidate for inclusion in subunit cytomegalovirus (CMV) vaccines, although data on gB antibody responses after natural infection are limited. [35S]-labeled gB was partially purified from cells infected with an adenovirus recombinant expressing gB and used in radioimmunoprecipitation assays to characterize responses in solid organ transplant recipients with primary (n = 11) or secondary (n = 8) CMV infection. Seropositive transplant patients without evidence of infection (n = 5) and healthy seroconverters (n = 7) were also studied. gB antibody developed concurrently with CMV-specific IgG, IgM, and neutralizing activity in transplant patients with primary infection. Sustained boosts in gB antibody were seen in patients with secondary infection, and healthy seroconverters developed early gB responses. These data imply that gB antibody is an integral part of the humoral response to CMV infection, and, in view of experimental data regarding immunogenicity, support a role for gB in subunit vaccines.

Adult↗

PubMed1994

The use of random-breakage mapping to locate the genes APN1 and YUH1 in the Saccharomyces genome, and to determine gene order near the left end of chromosome XI.

We have used the previously described technique of random-breakage mapping to locate the two yeast genes APN1 and YUH1. The APN1 locus is located approximately 235 kb from the left telomere of chromosome XI, and shows weak (approximately 53 cM) genetic linkage to ura1. The YUH1 locus is located approximately 140 kb from the right telomere of chromosome X, and genetically maps 3.6 cM distal to cdc11. In addition, we show by random-breakage mapping that TRP3 is located approximately 45 kb from the left telomere of chromosome XI, whereas FAS1 is approximately 110 kb from the same telomere. This supports a gene order on the left distal portion of chromosome XI that agrees with other physical reports but is inverted with respect to Edition 11 of the published genetic map. This report confirms that random-breakage mapping is a rapid and convenient method of locating cloned genes.

Chromosome Mapping↗

PubMed1994

Measurement of surgical costs: a clinical analysis.

Because of reduced health care funding it is becoming necessary for surgeons to take a greater interest in the costs of individual operations. This study reports costs directly measurable to the patient, and also the indirect costs of hospital overheads, an operating suite and teaching, which were 37, 10 and 15%, respectively (62%), of hospital budget. A scheme has been developed which could give surgeons a standard to report direct costs. Pre-admission, ward, operating room, recovery, intensive care and post-admission are defined as cost periods and the modalities of staff, equipment (capital, maintenance and replacement), imaging, laboratory and consumables apply to each. This strategy was applied to assess open cholecystectomy (OC) and laparoscopic cholecystectomy (LC) as an example. The direct costs for OC were $3706 and LC $2868, a difference of $838; the indirect and direct costs were OC $6004 and LC $4646, a difference of $1358. Thus indirect cost magnified the difference between the operations. Bed stay, density of nursing and use of disposable instruments were the major influence on direct costs. The individual cost advantage of a shorter bed stay may be countervailed by an increased hospital activity. The main patient benefit of new operations may be improved quality of life and more rapid return to work with prevention of salary losses. A method has been developed to define costs of a particular surgical operation with the purpose of stimulating surgeons' interest in this topic and developing a common style of reporting.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholecystectomy↗

PubMed1994

IL-6 mediated isotype specific suppression of hapten specific IgE in serum of BPO-KLH sensitized mice: role of IFN alpha in maintainance of hapten specific IgE responses.

The ability of IL-6 or IFN alpha or antibodies to these cytokines to regulate serum levels of hapten specific immunoglobulins (IgM, IgG1, IgE, IgA) was studied in BPO-KLH (benzylpenicilloyl-keyhole limpet hemocyanin) sensitized BALB/c mice at the peak of a hapten specific IgE antibody forming cell (AFC) response. To induce peak IgE responses, mice were injected intraperitonealy (i.p.) with BPO-KLH (10 micrograms) in aluminum hydroxide gel (alum) on days 0, 21, and 42. On day 44, mice were injected s.c. with IL-6 (100-1000 U), IFN alpha (1000-10,000 U), anti-IL-6 (100-1000 neutralizing units [NU]), or anti-IFN alpha (1000-10,000 NU). On day 46, levels of BPO specific IgM, IgG1, IgE and IgA in serum were determined (ELISA). Data are expressed as micrograms/ml. IL-6 suppressed BPO specific IgE in serum in isotype specific fashion (to > 90%), increasing IgA (approximately 3 fold), and leaving IgM and IgG1 unchanged. Since removal of endogenous IL-6 with anti-IL-6 increased serum IgE, and suppressed IgG1 (approximately 50%), with IgM and IgA unchanged, this suggests that IL-6 is an isotype specific suppressor of peak IgE responses and as such may be useful in the therapeutic management of atopic disease. IFN alpha treatment increased serum IgE levels (60%), and potentiated IgA responses (> 30 fold), with IgM and IgG1 unchanged. Since removal of endogenous IFN alpha with anti-IFN alpha decreased IgE levels (approximately 50%), increasing IgA, with IgM and IgG1 unchanged, this suggests a role for IFN alpha as an isotype specific helper of peak IgE responses and in maintenance of IgA responses.

Animals↗

PubMed1994

LIF and OM directly interact with a soluble form of gp130, the IL-6 receptor signal transducing subunit.

Oncostatin M and LIF are related members of a cytokine family that also includes IL-6, CNTF and G-CSF. These proteins exhibit overlapping biological properties and with the exception of G-CSF, they all appear to utilize gp130 as a signaling component of their high affinity receptor complexes. Recently it has been demonstrated that monomeric, membrane bound gp130 can directly bind OM. To further investigate the binding properties of gp130 we generated a soluble form of gp130, sgp130-Rg, to investigate potential gp130 interactions with OM and other members of this cytokine family. Using chemical crosslinking techniques we demonstrate that OM and LIF but not CNTF or IL-6 directly interact with sgp130-Rg. Since OM signaling can be prevented by binding gp130 with anti gp130 mAbs we also investigated the potential of sgp130-Rg to prevent the biological activities of both LIF and OM. Here we demonstrate that sgp130-Rg can bind LIF and OM preventing their biological activities on the TF-1 erythroleukemia cell line. This property suggests that sgp130-Rg may have therapeutic value in the specific prevention of LIF or OM mediated pathologies.

Animals↗

PubMed1993

Home truths.

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Aftercare↗

PubMed1993

Purification and analysis of streptococcal NADH peroxidase expressed in Escherichia coli.

Using the T7 RNA polymerase expression system, a modified plasmid vector has been developed which gives reliable, high level expression in Escherichia coli of the gene encoding streptococcal NADH peroxidase. The recombinant enzyme has been purified to homogeneity using a revised protocol which yields over 35 mg of pure protein per liter of culture. Recombinant NADH peroxidase is fully active and exhibits spectroscopic and redox properties identical to those for the enzyme purified from Streptococcus faecalis 10C1. Reductive titrations and thiol analyses confirm the presence of the unusual cysteine-sulfenic acid (Cys-SOH) redox center identified previously. N-terminal sequence analysis, analytical gel filtration, and preliminary x-ray diffraction data all confirm the structural identity of the recombinant and S. faecalis enzymes. Steady-state kinetic analysis of the peroxidase, coupled with results from static titration experiments is consistent with a limiting type of ternary complex mechanism and allows the determination of many of the corresponding kinetic constants. In addition, preliminary 1H NMR spectra of the enzyme at millimolar concentrations show good dispersion in the amide region and indicate that the recombinant peroxidase is suitable for one-dimensional NMR work with labeled amino acids.

Amino Acid Sequence↗

PubMed1993

Photodynamic therapy of subretinal neovascularization in the monkey eye.

Experimental subretinal neovascularization in the monkey eye was treated by photodynamic therapy with rose bengal. Following intravenous injection of rose bengal, the subretinal vessels were irradiated with filtered light. Successful treatment was achieved, provided the subretinal vessels were irradiated during the period in which the dye was present in and around the subretinal vessels but had already cleared from the retinal vasculature. The successfully treated lesions demonstrated replacement of the leaking and pooling subretinal vessels with a non-leaky scar. Morphologic evaluation revealed immediate destruction of the subretinal plexus, with minimal damage to the overlying retina. The destroyed subretinal tuft was replaced by a scar containing mainly fibroblasts embedded in collagen fibers. Our results suggest that photodynamic therapy is potentially useful for destruction of subretinal vessels without damaging the overlying retina.

Animals↗

PubMed1993

Diagnostic strategies in the management of acute upper gastrointestinal bleeding: patient and physician preferences.

BACKGROUND: Routine diagnostic endoscopy is commonly obtained for low-risk patients with acute upper gastrointestinal bleeding despite evidence from controlled trials that it does not improve patient outcome. OBJECTIVE: To determine whether endoscopy is being overutilized for these patients or whether considerations not addressed in the trials could justify its widespread use. METHODS: Twenty-five patients recovering from a recent hemorrhage and 22 primary care physicians used the analytic hierarchy process to perform an individualized analysis regarding the diagnostic management of acute upper gastrointestinal bleeding. The results were used to determine whether routine endoscopy was consistent with each subject's interpretation of relevant data and judgments regarding the relative importance of five management goals. The authors then compared the proportion of subjects in each group who preferred endoscopy over two non-endoscopy strategies (upper gastrointestinal series and no routine diagnostic test) with 85%, the current rate of endoscopy at the authors' hospital. RESULTS: Endoscopy was preferred by 92% (97.5% CI: 70%-98%) of the patients and 55% (97.5% CI: 31%-77%) of the physicians. The patients ranked identifying the cause of bleeding the second most important management goal after avoiding a poor outcome from the acute bleeding episode. CONCLUSIONS: The current rate of diagnostic endoscopy is higher than would be expected based on physicians' preferences but quite consistent with patients' preferences. Patients regard knowledge of the bleeding site as important, even if this information will not affect management or prognosis. Attempts to assess the use of diagnostic endoscopy and other diagnostic tests should take both patient preferences and the pure value of diagnostic information into account.

Adult↗

PubMed1993

Porphyrin profiles in the nestling European starling (Sturnus vulgaris): a potential biomarker of field contaminant exposure.

Porphyrin patterns in avian and mammalian tissues and/or excreta have been proposed as qualitative and quantitative biomarkers of exposure to polyhalogenated hydrocarbons, heavy metals, and other environmental contaminants. However, no widely distributed terrestrial species has been characterized as a suitable model in which to assess porphyrin profiles in the evaluation of environmental contaminant exposure. The European starling, whose nests can be readily established and manipulated on contaminated sites, has many qualities that accommodate controlled field research and that suggest its suitability for such assessments. In the present studies, we measured the total and individual porphyrin concentrations in liver, kidney, and fecal-urate excreta of nestling starlings from a noncontaminated field site from day of hatch through d 17 of the nestling period. Total as well as individual 8-, 7-, 6-, 5-, 4-, and 2-carboxyl porphyrin concentrations in liver, kidney, and fecal-urate excreta were readily detectable by high-performance liquid chromatography (HPLC) spectrofluorometric techniques and displayed tissue-specific patterns throughout the developmental period. Liver and fecal-urate porphyrin patterns were established by d 4 subsequent to hatch and remained constant through d 17 of development, whereas renal porphyrin profiles were constant throughout the entire developmental period. In controlled field studies, nestling starlings were treated with either HgCl2 or hexachlorobenzene (HCB), and tissue and excreta porphyrins were extracted and evaluated. The findings suggest that the nestling starling may serve as a suitable model species in which to monitor the effects of field contaminant exposure to wildlife based on chemical-induced changes in tissue or excreta porphyrin levels.

Animals↗

PubMed1993

Protein-sulfenic acid stabilization and function in enzyme catalysis and gene regulation.

Sulfenic acids (R-SOH) result from the stoichiometric oxidations of thiols with mild oxidants such as H2O2; in solution, however, these derivatives accumulate only transiently due to rapid self-condensation reactions, further oxidations to the sulfinic and/or sulfonic acids, and reactions with nucleophiles such as R-SH. In contrast, oxidations of cysteinyl side chains in proteins, where disulfide bond formation can be prevented and where the reactivity of the nascent cysteine-sulfenic acid (Cys-SOH) can be controlled, have previously been shown to yield stable active-site Cys-SOH derivatives of papain and glyceraldehyde-3-phosphate dehydrogenase. More recently, however, functional Cys-SOH residues have been identified in the native oxidized forms of the FAD-containing NADH peroxidase and NADH oxidase from Streptococcus faecalis; these two proteins constitute a new class within the flavoprotein disulfide reductase family. In addition, Cys-SOH derivatives have been suggested to play important roles in redox regulation of the DNA-binding activities of transcription factors such as Fos and Jun, OxyR, and bovine papillomavirus type 1 E2 protein. Structural inferences for the stabilization of protein-sulfenic acids, drawn from the refined 2.16-A structure of the streptococcal NADH peroxidase, provide a molecular basis for understanding the proposed redox functions of these novel cofactors in both enzyme catalysis and transcriptional regulation.

Catalysis↗

PubMed1993

The development of outpatient prospective payment systems and the use of ambulatory patient groups by private insurers.

Private insurers will likely move to APGs rapidly because of the key advantages that APGs provide. Not only is it necessary to have an outpatient classification system to make utilization review, quality assurance, and customer reporting more meaningful, outpatient prospective payment provides a foundation for the controls on outpatient payments that insurers have been seeking. Because of outpatient volume increases and constraints on inpatient payments that have led hospitals to increase outpatient charges more rapidly, most insurers believe that outpatient payment levels are currently beyond their control. Introduction of an outpatient prospective payment system will shift control over outpatient payment increases from providers to insurers, as has been the case for many insurers who have adopted DRG payment for inpatient services. Once APGs are in place, annual increases in payment amounts will be determined through insurer-provider negotiation or through contractual approaches that limit payment increases to changes in a price index.

Ambulatory Care↗