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Biomedical subjects

G McGuire

Publications and source records attributed to G McGuire.

At least 19 recordsLinked to original sources
PubMed1999

Complete upper airway obstruction during awake fibreoptic intubation in patients with unstable cervical spine fractures.

PURPOSE: To describe the presentation and management of complete upper airway obstruction with life threatening arterial oxygen desaturation that occurred during attempted awake fibreoptic intubation in two patients presenting with unstable C-spine injury. CLINICAL FEATURE: Complete upper airway obstruction occurred during awake fibreoptic intubation of two men (ASA II; 68 & 55 yr old) presenting with unstable C-spine fractures. In both cases, bag and mask ventilation with CPAP failed to relieve the progressive hypoxemia. A surgical airway was established urgently to oxygenate the two patients who were suffering progressive life-threatening oxygen desaturation. One patient had trans-cricothyroid jet ventilation performed through a 16G intravenous cannula prior to an urgent tracheostomy. In the other patient, an emergency tracheostomy was inserted. Interestingly, both patients had been sedated in the Neurosurgical Intensive Care Unit with morphine and benzodiazepines before their scheduled surgeries. The most likely etiology for the complete upper airway obstruction was laryngospasm due to inadequate topicalization of the airway and additional sedation given in the operating room. Neither patients suffered any new neurological deficits following these events. They went on to have uneventful surgeries. CONCLUSION: This case report suggest that prior to awake fibreoptic intubation, oxygenation, adequate topicalization with testing to verify the lack of pharyngeal and laryngeal responses and careful assessment of sedation levels in the operating room are prudent for a safe endoscopic intubation.

Aged↗
PubMed1998

TOPAL: recombination detection in DNA and protein sequences.

UNLABELLED: TOPAL scans a multiple sequence alignment for evidence of recombinant sequences, prior to phylogenetic analysis. AVAILABILITY: The TOPAL package may be accessed at http://www.bioss.sari.ac.uk/grainne, and by anonymous ftp at ftp.bioss. sari.ac.uk in the directory pub/phylogeny/topal. CONTACT: grainne@bioss.sari.ac.uk

Computational Biology↗
PubMed1997

Construction of a transcription map around the gene for ataxia telangiectasia: identification of at least four novel genes.

We have constructed YAC, PAC, and cosmid contigs in the ataxia-telangiectasia gene region and used the assembled clones to isolate expressed sequences by exon trapping and hybridization selection. In the interval between D11S1819 and D11S2029, exons and cDNAs for potentially 13 different genes were identified. Three of these genes, F37, K28, and 6.82, are large novel genes expressed in a variety of different tissues. K28 shows sequence homology to the Rab GTP binding protein family and gene 6.82 homology to the rabbit vasopressin activated calcium mobilizing receptor, while gene F37 has no homology to any known sequence in the database. Three further clones, exon 6.41 and cDNAs K22 and E74, from the interval between D11S1819 and D11S2029, appear to be expressed endogenous retrovirus sequences. The fourth large novel genes, E14, together with two further possible novel genes, E13 and E3, was identified from exons and cDNAs in the more telomeric 300-kb interval between markers D11S2029 and D11S2179. These are in addition to the genes for mitochondrial acetoacetyl-CoA-acetyltransferase (ACAT) and the ATM gene in the same region. Genes E3, E13, and E14 do not show homology to any known genes. K28, 6.82, ACAT, and ATM all appear to have the same transcriptional orientation toward the telomere.

Acetyl-CoA C-Acetyltransferase↗
PubMed1997

A graphical method for detecting recombination in phylogenetic data sets.

Current phylogenetic tree reconstruction methods assume that there is a single underlying tree topology for all sites along the sequence. The presence of mosaic sequences due to recombination violates this assumption and will cause phylogenetic methods to give misleading results due to the imposition of a single tree topology on all sites. The detection of mosaic sequences caused by recombination is therefore an important first step in phylogenetic analysis. A graphical method for the detection of recombination, based on the least squares method of phylogenetic estimation, is presented here. This method locates putative recombination breakpoints by moving a window along the sequence. The performance of the method is assessed by simulation and by its application to a real data set.

Computer Simulation↗
PubMed1997

Upper airway edema after carotid endarterectomy: the effect of steroid administration.

The objective of this study was to evaluate the effect of preoperative steroid administration on the site and extent of upper airway edema after carotid endarterectomy. The design was a randomized, prospective, double-blind controlled trial. Thirty-eight patients undergoing elective carotid endarterectomy (17 patients were in the steroid-treated group and 21 in the control group) were administered either 16 mg of dexamethasone or saline placebo prior to surgery. Computed tomograms (CT) scans of the neck were performed on the patients preoperatively and 24 h postoperatively. Measurements were taken from the CT scans of the airway transverse and anterior-posterior diameters at the levels of the hyoid bone, arytenoid cartilage, and cricoid cartilage. No postoperative neck hematomas were seen on the CT scans. Although neck edema was observed postoperatively, the upper airway dimensions were not statistically significantly different between the steroid and the control groups. We conclude that steroid administration immediately preoperatively has no clinical effect in reducing edema formation in the upper airway postcarotid endarterectomy.

Aged↗
PubMed1997

Evaluation of morphine versus fentanyl for postoperative analgesia after ambulatory surgical procedures.

Adequate postoperative analgesia without side effects is necessary to facilitate same-day discharge of ambulatory patients after ambulatory surgery. This study compared the use of intravenous morphine and fentanyl after painful ambulatory procedures with respect to analgesic efficacy, the incidence of side effects, and impact on the patient's readiness for discharge. Fifty-eight patients undergoing ambulatory surgery were prospectively randomized to receive morphine or fentanyl for postoperative analgesia and studied in double-blind fashion. The drugs were administered in equipotent doses in the postanesthesia care unit (PACU) and were titrated against pain scores until a visual analog score < 40 mm was achieved and the patient was satisfied with the level of analgesia. In the ambulatory surgical unit, oral analgesia was available. Pain scores, amount of analgesia used, the incidence of side-effects (nausea and vomiting, sedation and dizziness), the times to achieve recovery milestones, and fitness for discharge were studied. Equal amounts of morphine and fentanyl were used in the PACU, but pain scores were higher in the fentanyl group in the ambulatory surgical unit. In addition, the fentanyl group required more oral analgesia than the morphine group (69% vs 17%; P < 0.0002). The incidence of in-hospital side effects was similar. However, the morphine group had a more frequent incidence of postdischarge nausea and vomiting than the fentanyl group (59% vs 24%; P < 0.016). There was no significant difference in the duration of stay in the PACU (morphine vs fentanyl, 69 +/- 15 min vs 71 +/- 20 min), the times to achieve recovery milestones, and fitness for discharge (morphine vs fentanyl, 136 +/- 41 min vs 132 +/- 40 min). The short duration of fentanyl was not associated with faster discharge times; most patients required additional analgesia to control pain. Morphine produced a better quality of analgesia but was associated with an increased incidence of nausea and vomiting, the majority of which occurred after discharge.

Adult↗
PubMed1997

Effects of varying levels of positive end-expiratory pressure on intracranial pressure and cerebral perfusion pressure.

OBJECTIVE: To determine the influence of positive end-expiratory pressure (PEEP) on intracranial pressure and cerebral perfusion pressure. DESIGN: Neurosurgical intensive care patients requiring intracranial pressure monitoring and mechanical ventilation were studied in a randomized, controlled study. SETTING: Tertiary care, neurosurgical intensive care unit. PATIENTS: Eighteen patients were enrolled in the study. Patients had posttraumatic head injuries (n = 9), subarachnoid hemorrhage (n = 7), obstructive hydrocephalus (n = 1), and intracerebral hemorrhage of unknown cause (n = 1). INTERVENTIONS: Patients had PEEP levels of 5, 10, and 15 cm H2O applied to their lungs. MEASUREMENTS AND MAIN RESULTS: Changes in intracranial pressure, mean arterial pressure, and cerebral perfusion pressure were measured. The results were analyzed separately for patients with normal and increased intracranial pressure (> 15 mm Hg). PEEP at 5 cm H2O had no effect on intracranial pressure in the group with normal intracranial pressure. However, PEEP at 10 and 15 cm H2O produced a significant (p < .05) increase in intracranial pressure (1.9 and 1.5 mm Hg, respectively). In the group with increased intracranial pressure, no significant change in intracranial pressure occurred at any of the PEEP levels used. In both groups, cerebral perfusion pressure was unchanged throughout. CONCLUSIONS: In patients with normal intracranial pressure, PEEP at 5 cm H2O did not significantly alter intracranial pressure. The clinical relevance of the intracranial pressure increase at PEEP levels of 10 and 15 cm H2O is questionable because cerebral perfusion pressure did not change and remained > 60 mm Hg. In patients with increased intracranial pressure, higher levels of PEEP did not significantly change intracranial pressure or cerebral perfusion pressure.

Adult↗
PubMed1995

The excitability of human corticospinal neurons is depressed by thiopental.

BACKGROUND: We tested the effect of thiopental on the excitability of the corticospinal-motoneuron axis in normal human subjects. METHODS: Magnetic stimulation was used to excite the neurons in the motor cortex which give rise to the fast conducting corticospinal pathway. The characteristics of the composite excitatory post-synaptic potentials (EPSPs) produced in individual spinal motoneurons by cortical stimulation were derived from changes in the firing probability of voluntarily activated motor units of the first dorsal interosseous muscle. RESULTS: In 5 normal subjects, we found that thiopental, in incremental doses sufficient to sustain drowsiness (total dose 75 to 175 mg), significantly reduced the amplitude of these composite EPSPs. CONCLUSIONS: Thiopental reduced the facilitation of motoneurons from the cortex most likely by depressing cortical neurons.

Adult↗
PubMed1991

Hydrogen peroxide pretreatment of perfused canine vessels induces ICAM-1 and CD18-dependent neutrophil adherence.

BACKGROUND: Cytotoxic products of neutrophils (polymorphonuclear leukocytes, PMNs) contribute to ischemia-reperfusion injury of several tissues. Hydrogen peroxide (H2O2), one of the cytotoxic products of PMNs, also promotes the adherence of PMNs to cultured vascular endothelial cells in vitro. The present study was undertaken to determine if H2O2 also augmented adhesion of PMNs to intact vessels perfused ex vivo and to determine if H2O2-induced PMN adherence to intact canine carotid arteries and external jugular veins or to cultured canine venous endothelium is mediated by specific adherence ligands on the neutrophil and/or the endothelium. METHODS AND RESULTS: Vessels were perfused for 20 minutes with oxygenated Krebs-Henseleit bicarbonate buffer with and without H2O2, washed with buffer alone, and then exposed to 111In-labeled isolated PMNs (10(7) cells/vessel) under static conditions for up to 20 minutes before being washed again. Residual radioactivity retained by the washed vessel was counted as an index of PMN retention. The adherence of unlabeled PMNs to cultured endothelial cells was determined by a visual assay method after pretreatment of the endothelium with H2O2 for brief periods followed by washing. Perfusion of vessels with H2O2 produced a transient, concentration-dependent increase in PMN adhesion to both canine carotid arteries and external jugular veins that was two to four times that of control values at 1 mmol/l and declined at higher H2O2 concentrations. Peak retention of PMNs by canine carotid arteries occurred 10 minutes after exposure to 1 mmol/l H2O2 and then rapidly declined to control values; this effect was replicated by a second 20-minute exposure of canine carotid arteries to 1 mmol/l H2O2 60 minutes after the first exposure. Scanning and transmission electron microscopy revealed not only adherence of PMNs to but migration through the vascular endothelium of the carotid artery after H2O2 perfusion. The endothelium was intact in H2O2-treated arteries not exposed to PMNs. H2O2-induced PMN retention was completely inhibited by addition of catalase or the hydroxyl radical scavenger dimethylthiourea to the perfusate by incubation of the PMN with a monoclonal antibody (Mab) against CD18 (R15.7) or by perfusion of the H2O2-treated vessel with CL18/6, a Mab against canine ICAM-1 (intercellular adhesion molecule-1). Similar effects of Mabs on PMN adhesion to H2O2-pretreated cultured endothelium were noted. The retention of PMNs by vessels mechanically denuded of endothelial cells was markedly increased. H2O2 pretreatment of these vessels did not further augment PMN adherence, and no inhibitory effect of R15.7 was noted. Incubation of carotid arteries and PMNs with a specific platelet-activating factor antagonist, WEB2086, completely inhibited the H2O2-induced increased PMN retention by these vessels. CONCLUSIONS: These results indicate that H2O2 in the absence of evidence for permanent endothelial cell injury, can induce a transient, reversible, platelet-activating factor-dependent adherence of PMNs to vessels by mechanisms that depend on an intact endothelium and involve CD18 on the PMN and ICAM-1 on the endothelium.

Animals↗
PubMed1988

Hospice care of the intravenous drug user AIDS patient in a skilled nurse facility.

We report on the initial experience in hospice care for a predominantly poor, black and Hispanic intravenous drug user AIDS population in New York City. Hospice care was provided in a skilled nursing facility with a certified hospice program delivering home care and inpatient care. A formal education program preceded patient admission to familiarize the staff and institution with AIDS issues. Between February 1986 and January 1988, 62 of 175 referred patients were accepted for hospice admission. The patients' mean age was 39 years and all had AIDS dementia complex. The mean length of stay was 35 days (range 1-280 days) and a total of 2011 days of hospice care was provided. Ninety-one percent of hospice days were spent on the inpatient unit; only 9% of hospice days were provided at home. Despite the requirement of expensive inpatient hospice care for most patient days, the estimated savings in decreased costs compared to acute hospital inpatient care was $751,488 for these 62 patients. Continuing fear of transmission among hospice staff was not a major problem; however, several unanticipated problems arose including (a) inability to provide home services, (b) continued drug abuse, (c) increased staff stress, (d) difficulty maintaining confidentiality, (e) difficult interactions with funeral directors, and (f) unsupportive and inappropriate funding requirements. Hospice care of AIDS patients is feasible, humane, and cost effective but problems of the intravenous drug using population require special attention and program modifications if hospice care is to be provided for this substantial and growing AIDS population.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Raised liver associated enzyme activity and post-prandial bile acid concentrations in sera from treated diabetic outpatients.

Aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transferase activities were measured in sera from 411 diabetic outpatients and were raised in 26 (6.4%), 34 (8.3%) and 62 (15.2%) patients, respectively. Serum total bile acid concentrations were raised in 4 patients (1%). Percentage glycated hemoglobin A1, serum fructosamine concentration and plasma glucose concentration were also measured. No relationship between the presence of raised enzyme activity and mature age, short duration of diabetic treatment regimen or glycemic control was found. Twenty-six patients with an alanine aminotransferase activity greater than 60 U/l were reviewed at 23 +/- 6.5 weeks. The activity of this enzyme had fallen to within the reference interval in 15 (58%). In the other 11 patients, its median activity was 75 U/l (range 51-181 U/l). Median gamma-glutamyl transferase activity had risen in these 11 patients from 78 U/l to 93 U/l (P less than 0.01). No statistical differences in treatment regimen or glycemic control were found between these two groups. Raised liver-associated enzyme activity in treated stabilised diabetic outpatients should therefore not be attributed to poor glycemic control or diabetic treatment regimen.

Alanine Transaminase↗