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Biomedical subjects

M T Anderson

Publications and source records attributed to M T Anderson.

At least 19 recordsLinked to original sources
PubMed2006

Food-service establishment wastewater characterization.

Food-service establishments that use on-site wastewater treatment systems are experiencing pretreatment system and/or drain field hydraulic and/or organic overloading. This study included characterization of four wastewater parameters (five-day biochemical oxygen demand [BOD5]; total suspended solids [TSS]; food, oil, and grease [FOG]; and flow) from 28 restaurants located in Texas during June, July, and August 2002. The field sampling methodology included taking a grab sample from each restaurant for 6 consecutive days at approximately the same time each day, followed by a 2-week break, and then sampling again for another 6 consecutive days, for a total of 12 samples per restaurant and 336 total observations. The analysis indicates higher organic (BOD5) and hydraulic values for restaurants than those typically found in the literature. The design values for this study for BOD5, TSS, FOG, and flow were 1523, 664, and 197 mg/L, and 96 L/day-seat respectively, which captured over 80% of the data collected.

Food Services↗
PubMed2001

Routine fiberoptic endoscopic evaluation of swallowing following prolonged intubation: implications for management.

HYPOTHESIS: Fiberoptic endoscopic evaluation of swallowing (FEES) will identify patients who are at high risk for pulmonary aspiration due to swallowing dysfunction after prolonged intubation. Based on the results of FEES, dietary recommendations can be made to decrease the incidence of aspiration after prolonged intubation. DESIGN: Patients who were intubated for at least 48 hours were evaluated for swallowing dysfunction by bedside FEES within 48 hours of extubation. Differences in potential risk factors between aspirators and nonaspirators were analyzed. Dietary recommendations were made and patients were followed up for signs of clinically significant aspiration. SETTING: Community teaching hospital. PATIENTS: Fifty-one consecutive patients with no previously documented swallowing disorder who required a minimum of 48 hours of intubation for mechanical ventilation. INTERVENTIONS: Fiberoptic endoscopic evaluation of swallowing was performed by a speech pathologist. Initial diet orders were determined by results of the swallowing study. MAIN OUTCOME MEASURES: Incidence of swallowing dysfunction following prolonged intubation and incidence of clinically significant aspiration following initiation of oral feeding. RESULTS: Incidence of swallowing dysfunction was 56% (27/48); 12 (25%) of 48 patients were silent aspirators. In comparing aspirators with nonaspirators, no significant differences in potential risk factors or comorbidities were seen. Nineteen (70%) of the 27 patients aspirated with thin-consistency test liquids, and the other 8 (30%) with puree consistency. No patients in this study group developed a clinically significant aspiration following initiation of appropriately modified diets. CONCLUSIONS: Fiberoptic endoscopic evaluation of swallowing identified swallowing dysfunction in more than 50% of patients intubated for longer than 48 hours, many of whom are silent aspirators. Dietary recommendations based on FEES results prevented clinically significant aspiration.

Aged↗
PubMed2000

The dose-related effects of bolus esmolol on heart rate and blood pressure following laryngoscopy and intubation.

Many researchers have studied esmolol and its effects on heart rate and blood pressure. All studied relatively large doses of esmolol. Therefore, the purpose of the present study was to determine whether small doses of esmolol would blunt the transient increases in blood pressure and heart rate caused by laryngoscopy. This double-blind, prospective, randomized study included 61 subjects. The subjects were randomized to 1 of 3 groups: group 1 received esmolol, 0.2 mg/kg; group 2 received esmolol, 0.4 mg/kg; and group 3 received saline placebo. Groups 1 and 2 had smaller increases in heart rate than group 3. We also found that the 0.4 mg/kg dose significantly blunted the increase in mean arterial pressure seen in group 3. This study shows that small doses of esmolol may block the increases in heart rate and blood pressure resulting from laryngoscopy and intubation.

Adolescent↗
PubMed1998

Pairs of violet-light-excited fluorochromes for flow cytometric analysis.

We describe pairs of fluorochromes for use with the 407-nm line of a violet-light-enhanced krypton ion laser. These fluorochromes and a previously described violet-light-excited reporter variant, GFP-Vex, fall into two emission classes: blue for Cascade Blue, and green/yellow for Cascade Yellow, Lucifer Yellow, and GFP-Vex. Cascade Yellow is a new fluorochrome that we have synthesized and is used for the first time in the present study. The two emission classes are sufficiently different that Cascade Blue can be paired with Cascade Yellow, Lucifer Yellow, or GFP-Vex in flow cytometric analysis. Furthermore, with proper detection filters, these fluorochromes can be combined with all of the currently used fluorochromes in a three-laser FACS system. With these data, the total number of fluorochromes that can be used as antibody labels for simultaneous detection in combined FACS analysis increases to nine. This study demonstrates the sensitivity and power of the combined use of these reagents in a single eight-color analysis by identifying murine T-lymphocyte subsets that could not otherwise be readily distinguished.

Animals↗
PubMed1997

Glutathione deficiency is associated with impaired survival in HIV disease.

Glutathione (GSH), a cysteine-containing tripeptide, is essential for the viability and function of virtually all cells. In vitro studies showing that low GSH levels both promote HIV expression and impair T cell function suggested a link between GSH depletion and HIV disease progression. Clinical studies presented here directly demonstrate that low GSH levels predict poor survival in otherwise indistinguishable HIV-infected subjects. Specifically, we show that GSH deficiency in CD4 T cells from such subjects is associated with markedly decreased survival 2-3 years after baseline data collection (Kaplan-Meier and logistic regression analyses, P < 0.0001 for both analyses). This finding, supported by evidence demonstrating that oral administration of the GSH prodrug N-acetylcysteine replenishes GSH in these subjects and suggesting that N-acetylcysteine administration can improve their survival, establishes GSH deficiency as a key determinant of survival in HIV disease. Further, it argues strongly that the unnecessary or excessive use of acetaminophen, alcohol, or other drugs known to deplete GSH should be avoided by HIV-infected individuals.

Acetylcysteine↗
PubMed1997

Adjustable model of chronic left ventricular dysfunction.

BACKGROUND: As an adjunct to the development of skeletal muscle-powered left ventricular assist devices, an adjustable model of chronic left ventricular failure was developed. METHODS: Implantation of a left ventricular balloon to induce heart failure was accomplished via left thoracotomy. Upon recovery, left ventricular failure was simulated by manipulation of left ventricular balloon volume to chronically raise left atrial pressure. RESULTS: Left atrial pressure increased from a baseline of 9.3 +/- 0.7 mm Hg to 18.5 +/- 1.2 mm Hg, 20.2 +/- 1.8 mm Hg, and 26.0 +/- 1.2 mm Hg by the 2nd, 6th, and 10th postoperative week, respectively. Cardiac index declined from a baseline of 4.4 +/- 0.3 L x min(-1) x m(-2), reaching stability by the 8th postoperative week at 3.0 +/- 0.4 L x min(-1) x m(-2). Stroke volume index declined from 1.12 +/- 0.1 mL x kg(-1) x beat(-1) to 0.60 +/- 0.1 mL x kg(-1) x beat(-1) by the 10th postoperative week. Mean survival was 75 +/- 7 days. Causes of death included left ventricular failure, thromboembolism, and euthanasia. CONCLUSIONS: This method of simulating chronic left ventricular dysfunction proved to be stable and adjustable and has been useful in the development of ventricular assist systems.

Animals↗
PubMed1996

Simultaneous fluorescence-activated cell sorter analysis of two distinct transcriptional elements within a single cell using engineered green fluorescent proteins.

Green fluorescent protein (GFP) is widely used as a reporter gene in both prokaryotes and eukaryotes. However, the fluorescence levels of wild-type GFP (wtGFP) are not bright enough for fluorescence-activated cell sorting or flow cytometry. Several GFP variants were generated that are brighter or have altered excitation spectra when expressed in prokaryotic cells. We engineered two GFP genes with different combinations of these mutations, GFP(S65T,V163A) termed GFP-Bex1, and GFP(S202F,T203I,V163A) termed GFP-Vex1. Both show enhanced brightness and improved signal-to-noise ratios when expressed in mammalian cells and appropriately excited, compared with wtGFP. Each mutant retains only one of the two excitation peaks of the wild-type protein. GFP-Bex1 excites at 488 nm (blue) and GFP-Vex1 excites at 406 nm (violet), both of which are available laser lines. Excitation at these wavelengths allows for the independent analyses of these mutants by fluorescence-activated cell sorting, permitting simultaneous, quantitative detection of expression from two different genes within single mammalian cells.

3T3 Cells↗
PubMed1996

Elevation of plasma thioredoxin levels in HIV-infected individuals.

Thioredoxin (Trx), a ubiquitous protein intimately involved in redox and protein disulfide reductions, has been shown to be released from cells and to have cytokine-like activities. In addition, Trx has been implicated in the redox regulation of immunological responses and shown to be deficient in tissues from AIDS patients. In studies presented here, plasma Trx levels were measured by ELISA in plasma samples from HIV-infected individuals (n = 136) and HIV-negative controls (n = 47). To account for the release of Trx into plasma due to hemolysis, the Trx measurements were corrected according to the level of hemoglobin in the plasma sample. Data presented show that, in contrast to tissue Trx levels, corrected plasma Trx levels are significantly higher in HIV-infected individuals than in controls (P < 0.0001). Furthermore, approximately 25% of the HIV-infected individuals studied have plasma Trx levels greater than the highest levels found in controls (37 ng/ml). Detailed multiparameter FACS analysis of peripheral blood mononuclear cells (PBMC) from the infected individuals demonstrates that those with higher plasma Trx levels (37 ng/ml or greater) tend to have lower overall CD4 counts. In addition, increases in plasma Trx levels correlate with decreases in monochlorobimane staining (indicative of lower intracellular glutathione levels in PBMC) and with changes in surface antigen expression (CD62L, CD38 and CD20) that occur in the later stages of HIV infection. These correlations suggest that elevation of plasma Trx levels may be an important component of advanced HIV disease, perhaps related to the oxidative stress that often occurs at this stage.

Antigens, CD↗
PubMed1996

The importance of the postoperative anesthetic visit: do repeated visits improve patient satisfaction or physician recognition?

This study evaluates whether repeated postoperative visits by the anesthesiologist improve patient ability to recall the anesthesiologist's name and the patient's perception of and satisfaction with anesthesia services. In a randomized, prospective trial, 144 patients with an anticipated postoperative length of stay of at least three days were enrolled in three groups: Group A patients (n = 48) had one postoperative visit, Group B (n = 48) had two postoperative visits, and Group C (n = 48) had three postoperative visits. All postoperative visits were performed by the attending anesthesiologist on consecutive postoperative days. Patients were contacted two days after their last postoperative visit to complete a study questionnaire. Patients were able to recall the anesthesiologist's name significantly less frequently than the surgeon's name, and there was no difference in name recall among groups. Recall was not affected by patient age, sex, or ASA physical status; the mode of contact (telephone versus personal visit); the anesthesiologist's gender; the presence of preoperative medication; or the identity of the preoperative evaluator. Patients could identify the anesthesiologist's gender approximately 85% of the time, regardless of group, and were more likely to identify female anesthesiologists (P = 0.026, odds ratio 3.3). Patient evaluation of hospital, surgical, and anesthesia care was favorable in all groups and did not vary with group. Increasing the number of postoperative visits does not improve patient name recognition of the anesthesiologist or increase patient satisfaction with or perception of anesthesia services.

Age Factors↗
PubMed1995

CD8 naive T cell counts decrease progressively in HIV-infected adults.

We show here that CD8 naive T cells are depleted during the asymptomatic stage of HIV infection. Although overall CD8 T cell numbers are increased during this stage, the naive CD8 T cells are progressively lost and fall in parallel with overall CD4 T cell counts. In addition, we show that naive CD4 T cells are preferentially lost as total CD4 cell counts fall. These findings, presented here for adults, and in the accompanying study for children, represent the first demonstration that HIV disease involves the loss of both CD4 T cells and CD8 T cells. Furthermore, they provide a new insight into the mechanisms underlying the immunodeficiency of HIV-infected individuals, since naive T cells are required for all new T cell-mediated immune responses. Studies presented here also show that the well-known increase in total CD8 counts in most HIV-infected individuals is primarily due to an expansion of memory cells. Thus, memory CD8 T cells comprise over 80% of the T cells in PBMC from individuals with < 200 CD4/microliter, whereas they comprise roughly 15% in uninfected individuals. Since the naive and memory subsets have very different functional activities, this altered naive/memory T cell representation has significant consequences for the interpretation of data from in vitro functional studies.

Adult↗
PubMed1994

Separation of oxidant-initiated and redox-regulated steps in the NF-kappa B signal transduction pathway.

Studies presented here show that overall NF-kappa B signal transduction begins with a parallel series of stimuli-specific pathways through which cytokines (tumor necrosis factor alpha), oxidants (hydrogen peroxide and mitomycin C), and phorbol ester (phorbol 12-myristate 13-acetate) individually initiate signaling. These initial pathways culminate in a common pathway through which all of the stimulating agents ultimately signal NF-kappa B activation. We distinguish the stimuli-specific pathways by showing that the oxidative stimuli trigger NF-kappa B activation in only one of two human T-cell lines (Wurzburg but not Jurkat), whereas tumor necrosis factor alpha and phorbol 12-myristate 13-acetate readily stimulate in both lines. We propose the common pathway as the simplest way of accounting for the common requirements and properties of the signaling pathway. We include a redox-regulatory mechanism(s) in this common pathway to account for the previously demonstrated redox regulation of NF-kappa B activation in Jurkat cells (in which oxidants don't activate NF-kappa B); we put tyrosine phosphorylation in the common pathway by showing that kinase activity (inhibitable by herbimycin A and tyrphostin 47) is required for NF-kappa B activation by all stimuli tested in both cell lines. Since internal sites of oxidant production have been shown to play a key role in the cytokine-stimulated activation of NF-kappa B, and since tyrosine kinase and phosphatase activities are known to be altered by oxidants, these findings suggest that intracellular redox status controls NF-kappa B activation by regulating tyrosine phosphorylation event(s) within the common step of the NF-kappa B signal transduction pathway.

Benzoquinones↗
PubMed1994

Redox regulation of signal transduction: tyrosine phosphorylation and calcium influx.

Studies presented here show that altering the intracellular redox balance by decreasing glutathione levels profoundly affects early signal transduction events in human T cells. In a T-cell receptor (TCR) signaling model, short-term pretreatment with buthionine sulfoximine, which specifically decreases intracellular glutathione, essentially abrogates the stimulation of calcium influx by anti-CD3 antibodies without significantly impairing other aspects of TCR-initiated signal transduction, such as overall levels of TCR-stimulated tyrosine phosphorylation. In an inflammatory-cytokine signaling model, the failure of tumor necrosis factor alpha to stimulate more than minimal tyrosine phosphorylation in lymphocytes is overcome by buthionine sulfoximine pretreatment--i.e., tumor necrosis factor alpha stimulates extensive tyrosine phosphorylation in glutathione-depleted lymphocytes. These redox-dependent changes in T-cell responsiveness suggest that the glutathione deficiency that we and others have demonstrated in human immunodeficiency virus-infected individuals may contribute significantly to the immunodeficiency and the increased inflammatory reactions in these individuals.

Aluminum Compounds↗
PubMed1994

Intrathecal sufentanil compared to epidural bupivacaine for labor analgesia.

BACKGROUND: Although intrathecal sufentanil has been reported to provide rapid-onset, complete analgesia lasting 1-3 h for the first stage of labor, no well-controlled double-blind study has compared this technique to the use of epidurally administered local anesthetics. METHODS: Fifty healthy parturient women requesting labor analgesia were studied. In a combined spinal-epidural technique, a spinal needle was inserted through the epidural needle before insertion of the epidural catheter. Patients were randomly assigned to receive either intrathecal sufentanil (10 micrograms) and epidural saline, or intrathecal saline and epidural bupivacaine (30 mg). Visual analog scores for pain, blood pressure, heart rate, sensory levels, and the incidence of nausea, pruritus, and motor blockade were recorded. RESULTS: Patients receiving intrathecal sufentanil had significantly lower visual analog pain scores at 5, 15, and 30 min after injection and a greater duration of analgesia before requesting additional medication (mean 123 vs. 68 min for those receiving bupivacaine; P < 0.05). These patients also experienced pruritus more frequently but motor blockade less frequently than patients receiving epidural bupivacaine. The groups exhibited dermatomal sensory deficits to pin prick as well as bradycardia and hypotension with equal frequency. The length of labor and type of delivery were similar between the groups. No patient experienced a post-dural puncture headache. CONCLUSIONS: The rapid onset of analgesia and lack of motor blockade from intrathecal sufentanil injection may be advantageous in certain clinical situations. With this technique, however, pruritus is common; hypotension may occur; and extensive dermatomal spread suggests that early-onset respiratory depression could occur. Therefore, blood pressure and respiratory adequacy should be monitored if intrathecal sufentanil is used.

Adult↗