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Biomedical subjects

M Green

Publications and source records attributed to M Green.

At least 289 records · Page 16Linked to original sources
PubMed1995

Evaluation of a portable clinical blood analyzer in the emergency department.

OBJECTIVE: To assess the potential effects of rapid bedside blood analysis on patient management in the ED. METHODS: A prospective, nonrandomized clinical study was conducted over a consecutive ten-month period (August 1992 to May 1993). Blood samples drawn from a convenience sample of 960 patients for analysis of Na+, K+, Cl-, BUN, glucose, and/or hematocrit (Hct) were simultaneously analyzed by portable clinical analyzer (PCA) and by routine methods in the central laboratory. Caregivers were blinded to the PCA values; patient care was based solely on central laboratory results. Physicians were surveyed after the completion of patient care. RESULTS: The PCA results were available 31 minutes (mean) sooner than were the central laboratory results for Hct, 43 minutes faster for Na+, K+, and Cl-, and 44 minutes faster for BUN and glucose. Except for Hct and glucose, the values obtained from the PCA were not significantly different from the central clinical blood analyzer laboratory values. When surveyed, the physicians caring for the patients reported that had the PCA results been available, a different or an earlier therapeutic approach would have resulted in 9.5% of the cases. The decision to release or admit the patient was based on one or more of the laboratory values for 10.7% of patients sampled. In no case in this series did a physician report that final ED clinical outcome would have been affected. CONCLUSIONS: In our ED, the PCA yielded faster reporting of laboratory values. These earlier results might have reduced the length of stay in the ED for 17.3% of patients studied. Selective use of a handheld portable analyzer might decrease time to therapeutic interventions and time to disposition.

Adult↗
PubMed1995

A new improved sub-unit vaccine for plague: the basis of protection.

In this study, we have determined the limit of protection achievable by immunisation with sub-units of Yersinia pestis against the development of plague in an experimental animal model. Co-immunisation with the purified culture-derived F1 and the recombinant V sub-units afforded a greater level of protection than with either sub-unit alone. The protection given by the combined sub-units was several orders of magnitude greater than that afforded by the whole cell killed (Cutter USP) vaccine and was equivalent to that achieved by vaccination with EV76, the live attenuated Y. pestis vaccine strain. However, the combined sub-unit vaccine has clear advantages over the live vaccine in terms of safety of use and absence of side-effects.

Animals↗
PubMed1995

DNA hybridization and contour-clamped homogeneous electric field electrophoresis for identification of enterococci to the species level.

In this study, 113 Enterococcus faecium, 37 Enterococcus faecalis, 24 Enterococcus gallinarum, 15 Enterococcus raffinosus, and 13 Enterococcus casseliflavus clinical isolates and American Type Culture Collection (ATCC) strains were evaluated by contour-clamped homogeneous electric field electrophoresis. Thirty-one of the E. faecium, 22 of the E. faecalis, 24 of the E. gallinarum, 15 of the E. raffinosus, and 13 of the E. casseliflavus isolates were also evaluated by DNA-DNA hybridization. Genomic DNAs from type strains E. faecalis ATCC 19433, E. faecium ATCC 19434, E. gallinarum ATCC 49573, E. raffinosus ATCC 49427, and E. casseliflavus ATCC 25788 were labeled with biotin for use as probes. E. faecalis differed from all other species in always having a largest fragment of > 400 kb. E. gallinarum was different from all other species in having all SmaI fragments of < 200 kb. Biotin-labeled probes showed a high degree of hybridization with genomic DNA from the same species and a low degree of hybridization when hybridized to genomic DNA from different species for all isolates tested except for four isolates identified as E. faecium by conventional biochemical methods. The DNA from these four isolates hybridized strongly to DNA from E. gallinarum ATCC 49573 and weakly to E. faecium ATCC 19434 DNA and had all SmaI fragments of < 200 kb in size. These data suggest that these isolates are nonmotile E. gallinarum. DNA from each ATCC type strain hybridized strongly with itself and had only a low degree of hybridization with DNA from other ATCC type strains tested. These results suggest that contour-clamped homogeneous electric field electrophoresis patterns and DNA-DNA hybridization with biotin-labeled probes may be of use for species differentiation of some enterococci.

Blotting, Southern↗
PubMed1995

Comparison of field inversion gel electrophoresis with contour-clamped homogeneous electric field electrophoresis as a typing method for Enterococcus faecium.

Direct comparisons between contour-clamped homogeneous electric field (CHEF) electrophoresis and field inversion gel electrophoresis (FIGE) to determine the epidemiology of antibiotic-resistant enterococci have not been previously published. Fifty non-beta-lactamase-producing, ampicillin-resistant Enterococcus faecium isolates and 10 vancomycin-resistant E. faecium strains collected from multiple centers were analyzed in a blinded fashion by CHEF electrophoresis and FIGE after digestion with SmaI. Isolates were considered clonally related if there was a difference of three of fewer bands between electrophoretic patterns. Agreement between CHEF electrophoresis and FIGE was seen for 12 of 13 identified groups of ampicillin-resistant E. faecium and 7 of 7 groups of vancomycin-resistant E. faecium. The lone discordance was accounted for by a fourth band difference between two strains recognized near 350 kb by CHEF electrophoresis but not by FIGE, placing them into different clonal groups. Better band separation was noted in the 50- to 200-kb range for FIGE, while CHEF electrophoresis revealed better resolution over 250 kb more reliably, including detection of some bands not seen on FIGE. Molecular epidemiologic investigations of E. faecium by either technique should provide comparable results.

Ampicillin Resistance↗
PubMed1995

Repression in vitro, by human adenovirus E1A protein domains, of basal or Tat-activated transcription of the human immunodeficiency virus type 1 long terminal repeat.

Human adenovirus E1A proteins can repress the expression of several viral and cellular genes. By using a cell-free transcription system, we demonstrated that the gene product of the E1A 12S mRNA, the 243-residue protein E1A243R, inhibits basal transcription from the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR). The HIV-1 transactivator protein Tat greatly stimulates transcription from the viral promoter in vitro. However, E1A243R can repress Tat-activated transcription in vitro. Strong repression of both basal and Tat-activated transcriptions requires only E1A N-terminal amino acid residues 1 to 80. Deletion analysis showed that E1A N-terminal amino acids 4 to 25 are essential for repression, whereas amino acid residues 30 to 49 and 70 to 80 are dispensable. Transcriptional repression by E1A in the cell-free transcription system is promoter specific, since under identical conditions, transcription of the adenovirus major late promoter and the Rous sarcoma virus LTR promoter was unaffected. The repression of transcription by small E1A peptides in vitro provides an assay for investigation of molecular mechanisms governing E1A-mediated repression of both basal and Tat-activated transcriptions of the HIV-1 LTR promoter.

Adenovirus E1A Proteins↗
PubMed1995

Molecular cloning and characterization of a cellular protein that interacts with the human immunodeficiency virus type 1 Tat transactivator and encodes a strong transcriptional activation domain.

The mechanism by which human immunodeficiency virus type 1 Tat transactivates the long terminal repeat promoter is not understood. It is generally believed that Tat has one or more transcription factors as its cellular target. One might expect a cellular target for Tat to possess several properties, including (i) the ability to bind to the Tat activation region, (ii) the possession of a transcriptional activation domain, and (iii) the ability to contact the cellular transcription machinery. Here we describe the cloning, expression, and characterization of a human protein, termed TAP (Tat-associated protein), which possesses some of these properties. TAP is highly conserved in eukaryotes and is expressed in a variety of human tissues. The major intracellular species of TAP is a highly acidic 209-amino-acid protein that likely is formed by removal of a highly basic 70-amino-acid N-terminal segment from a primary translation product. By deletion analysis, we have identified a TAP C-terminal region rich in acidic amino acids and leucine residues which acts as a strong transcriptional activator when bound through GAL4 sites upstream of the core long terminal repeat promoter, as well as flanking sequences that mask the activation function. Amino acid substitution of two leucine residues within the core activation region results in loss of the TAP activation function. Two lines of evidence suggest that Tat interacts with TAP in vivo. First, promoter-bound Tat can recruit a TAP/VP16 fusion protein to the promoter. Second, transiently expressed Tat is found associated with endogenous TAP, as demonstrated by coimmuno-precipitation analysis. As shown in an accompanying report, the TAP activation region binds the Tat core activation region and general transcription factor TFIIB (L. Yu, P.M. Loewenstein, Z. Zhang, and M. Green, J. Virol. 69:3017-3023, 1995). These combined results suggest the hypothesis that TAP may function as a coactivator that bridges Tat to the general transcription machinery of the cell via TFIIB.

3T3 Cells↗
PubMed1995

In vitro interaction of the human immunodeficiency virus type 1 Tat transactivator and the general transcription factor TFIIB with the cellular protein TAP.

We have reported the molecular cloning, expression, and characterization of a human cellular protein, TAP, which possesses a strong transcriptional activation domain and binds the human immunodeficiency virus type 1 Tat transactivator in vitro and in vivo (L. Yu, Z. Zhang, P.M. Loewenstein, K. Desai, Q. Tang, D. Mao, J.S. Symington, and M. Green, J. Virol. 69:3007-3016, 1995). Here we show that TAP binds the general transcription factor TFIIB. Furthermore, we delineate the binding domains of TAP, Tat, and TFIIB, as well as measure the strengths and specificity of these protein-protein interactions. TAP binds strongly to Tat, with a Kd of (approximately 2 to 5) x 10(-7) M. The Tat activation region contains a 17-amino-acid conserved core domain which is the single contact site for TAP. Single-amino-acid substitutions within the Tat core domain inactivate transactivation in vivo and in vitro and greatly reduce binding of Tat to TAP in vitro. TAP binds strongly to TFIIB, with about the same Kd as for Tat. The interaction between TAP and TFIIB requires a sequence near the carboxy terminus of TFIIB which is also required for binding the strong acidic activator VP16. The contact sites for Tat and TFIIB map within the TAP C-terminal region, which contains the TAP activation domain. These combined results are consistent with the hypothesis that TAP is a cellular coactivator that bridges the Tat transactivator to the general transcription machinery via TFIIB.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1995

A heat shock-responsive domain of human HSF1 that regulates transcription activation domain function.

Human heat shock factor 1 (HSF1) stimulates transcription from heat shock protein genes following stress. We have used chimeric proteins containing the GAL4 DNA binding domain to identify the transcriptional activation domains of HSF1 and a separate domain that is capable of regulating activation domain function. This regulatory domain conferred heat shock inducibility to chimeric proteins containing the activation domains. The regulatory domain is located between the transcriptional activation domains and the DNA binding domain of HSF1 and is conserved between mammalian and chicken HSF1 but is not found in HSF2 or HSF3. The regulatory domain was found to be functionally homologous between chicken and human HSF1. This domain does not affect DNA binding by the chimeric proteins and does not contain any of the sequences previously postulated to regulate DNA binding of HSF1. Thus, we suggest that activation of HSF1 by stress in humans is controlled by two regulatory mechanisms that separately confer heat shock-induced DNA binding and transcriptional stimulation.

Amino Acid Sequence↗
PubMed1995

Unilateral magnetic stimulation of the phrenic nerve.

BACKGROUND: Electrical stimulation of the phrenic nerve is a useful non-volitional method of assessing diaphragm contractility. During the assessment of hemidiaphragm contractility with electrical stimulation, low twitch transdiaphragmatic pressures may result from difficulty in locating and stimulating the phrenic nerve. Cervical magnetic stimulation overcomes some of these problems, but this technique may not be absolutely specific and does not allow the contractility of one hemidiaphragm to be assessed. This study assesses both the best means of producing supramaximal unilateral magnetic phrenic stimulation and its reproducibility. This technique is then applied to patients. METHODS: The ability of four different magnetic coils to produce unilateral phrenic stimulation in five normal subjects was assessed from twitch transdiaphragmatic pressure (TwPDI) measurements and diaphragmatic electromyogram (EMG) recordings. The results from magnetic stimulation were compared with those from electrical stimulation. To determine whether the magnetic field affects the contralateral phrenic nerve as well as the intended phrenic nerve, EMG recordings from each hemidiaphragm were compared during stimulation on the same side and the opposite side relative to the recording electrodes. The EMG recordings were made from skin surface electrodes in five normal subjects and from needle electrodes placed in the diaphragm during cardiac surgery in six patients. Similarly, the direction of hemidiaphragm movement was evaluated by ultrasonography. To determine the usefulness of the technique in patients the 43 mm mean diameter double coil was used in 54 patients referred for assessment of possible respiratory muscle weakness. These results were compared with unilateral electrical phrenic stimulation, maximum sniff PDI, and TwPDI during cervical magnetic stimulation. RESULTS: In the five normal subjects supramaximal stimulation was established for eight out of 10 phrenic nerves with the 43 mm double coil. Supramaximal unilateral magnetic stimulation produced a higher TwPDI than electrical stimulation (mean (SD) 13.4 (2.5) cm H2O with 35 mm coil; 14.1 (3.8) cm H2O with 43 mm coil; 10.0 (1.7) cm H2O with electrical stimulation). Spread of the magnetic field to the opposite phrenic nerve produced a small amplitude contralateral diaphragm EMG measured from skin surface electrodes which reached a mean of 15% of the maximum EMG amplitude produced by ipsilateral stimulation. Similarly, in six patients with EMG activity recorded directly from needle electrodes, the contralateral spread of the magnetic field produced EMG activity up to a mean of 3% and a maximum of 6% of that seen with ipsilateral stimulation. Unilateral magnetic stimulation of the phrenic nerve was rapidly achieved and well tolerated. In the 54 patients unilateral magnetic TwPDI was more closely related than unilateral electrical TwPDI to transdiaphragmatic pressure produced during maximum sniffs and cervical magnetic stimulation. Unilateral magnetic stimulation eliminated the problem of producing a falsely low TwPDI because of technical difficulties in locating and adequately stimulating the nerve. Eight patients with unilateral phrenic nerve paresis, as indicated by a unilaterally elevated hemidiaphragm on a chest radiograph and maximum sniff PDI consistent with hemidiaphragm weakness, were all accurately identified by unilateral magnetic stimulation. CONCLUSIONS: Unilateral magnetic phrenic nerve stimulation is easy to apply and is a reproducible technique in the assessment of hemidiaphragm contractility. It is well tolerated and allows hemidiaphragm contractility to be rapidly and reliably assessed because precise positioning of the coils is not necessary. This may be particularly useful in patients. In addition, the anterolateral positioning of the coil allows the use of the magnet in the supine patient such as in the operating theatre or intensive care unit.

Adult↗
PubMed1995

Mouth pressure in response to magnetic stimulation of the phrenic nerves.

BACKGROUND: Diaphragm strength can be assessed by the measurement of gastric (TW PGA), oesophageal (TW POES), and transdiaphragmatic (TW PDI) pressure in response to phrenic nerve stimulation. However, this requires the passage of two balloon catheters. A less invasive method of assessing diaphragm contractility during stimulation of the phrenic nerves would be of clinical value. A study was undertaken to determine whether pressure measured at the mouth (TW PM) during magnetic stimulation of the phrenic nerves accurately reflects TW POES, and to investigate the relations between TW PM and TW PDI; and also to see whether glottic closure and twitch potentiation can be avoided during these measurements. METHODS: Eight normal subjects and eight patients with suspected respiratory muscle weakness without lung disease were studied. To prevent glottic closure magnetic stimulation of the phrenic nerves was performed at functional residual capacity during a gentle expiratory effort against an occluded airway incorporating a small leak. TW PDI, TW POES, and TW PM were recorded. Care was taken to avoid potentiation of the diaphragm. RESULTS: In normal subjects mean TW PM was 13.7 cm H2O (range 11.3-16.1) and TW POES was 13.3 cm H2O (range 10.4-15.9) with a mean (SD) difference of 0.4 (0.81) cm H2O. In patients mean TW PM was 9.1 cm H2O (range 0.5-18.2) and TW POES was 9.3 (range 0.7-18.7) with a mean (SD) difference of -0.2 (0.84) cm H2O. The relation between TW PM and TW PDI was less close but was well described by a linear function. In patients with diaphragm weakness (low sniff PDI) TW PM was < 10 cm H2O. CONCLUSIONS: TW PM reliably reflects TW POES and can be used to predict TW PDI in normal subjects and patients without lung disease. TW PM may therefore be a promising non-invasive, non-volitional technique for the assessment of diaphragm strength.

Adult↗
PubMed1995

Measurement of urinary desmosine as an indicator of acute pulmonary disease.

A modified radioimmunoassay (RIA) for desmosine in the urine was investigated as a tool for the rapid estimation of lung elastin catabolism. Cystic fibrosis (CF) and oxygen toxicity were chosen as conditions that might show altered elastin destruction. Using an antibody bound to magnetic particles the RIA was adapted to handle large numbers of samples requiring only 50 microliters or urine. The experiments show that it was not necessary to hydrolyze or extract the urine prior to assay and that collecting spot urines and normalizing the data to urine creatinine gives the same interpretation of the data as total desmosine in a 24-hour collection. Urine desmosine levels were elevated in 10 of 16 patients with CF; however, daily fluctuations were considerable in some subjects, varying as much as 5-fold and underlining the importance of assaying several consecutive days of urine in acute disorders for an accurate estimate of desmosine excretion. The RIA for desmosine is a rapid and sensitive assay that requires no sample preparation and could be applied to clinical situations that require large numbers of samples.

Acute Disease↗
PubMed1995

Exhaustive treadmill exercise does not reduce twitch transdiaphragmatic pressure in patients with COPD.

Reduced diaphragm contractility has been described in normal subjects after whole body endurance exercise, and it indicates low frequency fatigue (LFF); it is unknown whether LFF is of clinical importance. We therefore studied the effect of treadmill exercise to exhaustion on diaphragm contractility in six patients with severe chronic obstructive pulmonary disease (COPD) (mean FEV1, 0.71, 27% predicted). The subjects first performed a short (control), treadmill walk and then, after resting, a second walk to a state of severe dyspnea. Cervical magnetic stimulation of the phrenic nerve roots was performed at the start of the study and 20 and 30 min after each walk. The twitch transdiaphragmatic pressure (Tw Pdi) was reproducible (mean coefficient of variation, 5.3%; range, 2 to 12.5%). Mean Twi Pdis were 18.4 cm H2O at baseline and 19.6 cm H2O and 19.2 cm H2O 20 and 30 min after the control walk. At the same times after the exhaustive walk, mean Tw Pdis were 19.6 and 20.4 cm H20. Tw Pdi was not reduced by exhaustive treadmill walking (p > 0.9), and a power calculation showed that the study had a 95% chance of detecting a 10% fall at the 5% significance level. We conclude that Tw Pdi is not reduced when patients with severe COPD walk to a state of extreme breathlessness and that therefore low frequency fatigue of the diaphragm does not occur.

Aged↗
PubMed1995

Anxiety in elderly hearing impaired persons.

The association between experiences of hearing impairment and signs of anxiety in 42 elderly hearing impaired patients at a hearing aid centre was investigated. Subjects completed the Hearing Coping Assessment, the Beck Anxiety Inventory, and an audiometric test of hearing. Analysis showed low scores on anxiety and hearing problems compared with other studies. Moreover, scores on anxiety did not correlate with pure tone thresholds for hearing but with self-reported hearing problems (r = .31). Anxiety is important, but it is possible that signs of depression are more strongly related to self-perceived hearing handicap.

Aged↗
PubMed1995

Comparison of M and T type antigen testing to field inversion gel electrophoresis in the differentiation of strains of group A streptococcus.

Recent clusters of patients with acute rheumatic fever and invasive group A Streptococcus (GAS) have stimulated renewed interest in the epidemiology of streptococcal infections. We compared conventional serotyping for M and T antigens and serum opacity factor with field inversion gel electrophoresis (FIGE) for distinguishing among GAS. Fifteen pairs of throat isolates obtained from children positive for GAS before and after therapy were evaluated by conventional serotyping and by FIGE after SmaI digestion. Ten of the 15 pairs were identical by serotyping. FIGE correctly identified the 10 concordant and 5 discordant pairs. Individual clones were identified within each M type tested, including analysis performed on additional isolates of M1 and M3 obtained from the Centers for Disease Control and Prevention. This preliminary experience suggests that FIGE can successfully determine whether serial isolates from a given patient represent persistence of one strain or acquisition of a new strain of GAS and that this method might provide an alternative typing system for GAS.

Antigens, Bacterial↗
PubMed1995

The cost effectiveness of stereotactic radiosurgery versus surgical resection in the treatment of solitary metastatic brain tumors.

Solitary metastatic brain tumors are the most common intracranial neoplasms encountered by neurosurgeons. Surgical resection of brain metastasis with whole brain radiotherapy (WBR) significantly increases survival in comparison with WBR alone. Stereotactic radiosurgery (SR) seems to provide results that are similar to those of surgical resection. To analyze the economic efficiency of these different treatments, we compared the results of surgical resection and SR as reported in the medical literature between 1974 and 1994. We included studies in which: 1) at least 75% of patients received WBR; 2) study dates were in the computed tomography era (after 1975); 3) operative morbidity, mortality, and median survival were reported; 4) study dates were not included in a more recent update or review; 5) tumor histologies were reported; and 6) the cobalt-60 gamma unit was used for SR. Three surgical resection studies and one SR study met all entry requirements. The WBR baseline was developed from two prospective, randomized trials and used for incremental cost effectiveness analysis. We developed a model of typical resource usage for uncomplicated procedures, reported complications, and subsequent craniotomies (for recurrent tumor or radiation necrosis) for both treatment options. Costs were estimated from the societal viewpoint using the 1992 Medicare Provider Analysis and Review database with average cost:charge ratios for surgery and WBR. A survey of capital and operating costs from five sites was used for radiosurgery. Our analysis revealed that radiosurgery had a lower uncomplicated procedure cost ($20,209 versus $27,587), a lower average complication cost per case ($2,534 versus $2,874), and a lower total cost per procedure ($22,743 versus $30,461), was more cost effective ($24,811 versus $32,149 per life year), and had a better incremental cost effectiveness ($40,648 versus $52,384 per life year) than surgical resection. A sensitivity analysis revealed that large changes in key assumptions would be required to change the analysis outcome. Equalization of the incremental cost effectiveness of the two treatments would require one of the following: 1) a 38.7% reduction in SR annual case volume, 2) a 34.7% increase in SR procedure cost, 3) a 18.8% reduction in surgical resection procedure cost, 4) a 240.5% increase in SR morbidity cost, 5) a 12.7% reduction in SR median survival, 6) a 16.8% increase in surgical resection median survival. Elimination of all surgical resection morbidity cost would still result in superior incremental cost effectiveness for SR.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain Neoplasms↗
PubMed1995

Successful alternatives to alternate site testing. Use of a pneumatic tube system to the central laboratory.

We evaluated the use of several modes of alternate site versus central laboratory testing in our hospital to provide improved processing of stat specimens from the Emergency Department and the Operating Room. Using the principle of parallel processing for sample analysis, coupled with installation of a computerized pneumatic tube specimen delivery system, we provided improved turnaround time, a larger test menu, and 24-hour-a-day service from the central laboratory. As a result, the satellite laboratory in the Emergency Department was closed and 16 full-time equivalent positions were saved in the hospital. A separate tube zone was established for the Operating Room, and a critical care whole-blood test unit was established in the central laboratory, providing 7-minute turnaround time for blood gases, electrolytes, and glucose. Testing in the Operating Room by nonlaboratory personnel was discontinued.

Centralized Hospital Services↗
PubMed1995

Influence of temperature on long-term keratin immunoreactivity for oral exfoliative cytology.

We previously showed that keratin profiles can be of value in the diagnosis of oral cancer when using exfoliative cytology. In the future, they may form part of a screening program for oral cancer. This study evaluated the influence of long-term storage on keratin expression. Smears were collected from the clinically normal buccal mucosa and dorsal tongue of 22 patients. Half were stored in a refrigerator (5 degrees C) and half in a freezer (-70 degrees C). A total of 528 smears were collected. A panel of three antikeratin antibodies (LP34, AE8 and 1C7) was used to identify the preservation of keratin expression (graded as absent, few cells positive or many cells positive). The results for smears from dorsal tongue indicated that many cells were impermeable by the antikeratin antibodies. However, a satisfactory level of keratin immunoreactivity was observed in smears from buccal mucosa stored at -70 degrees C for over one year. Results for storage at 5 degrees C for both sites were inadequate after one month. Thus, smears from nonkeratinized oral sites may be stored at -70 degrees C for at least one year without a profound loss of keratin immunoreactivity, thus allowing examination of archival material.

Cold Temperature↗