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Biomedical subjects

W Miles

Publications and source records attributed to W Miles.

13 recordsLinked to original sources
PubMed2000

Cardiac troponin I predicts myocardial dysfunction in aneurysmal subarachnoid hemorrhage.

OBJECTIVES: We studied the incidence of myocardial injury in aneurysmal subarachnoid hemorrhage (SAH) using the more sensitive cardiac troponin I (cTnI) assay, correlated changes in cTnI with creatine kinase, MB fraction (CK-MB), myoglobin, and catecholamine metabolite assays, and examined the predictive value of changes in cTnI for myocardial dysfunction. BACKGROUND: Myocardial injury in aneurysmal SAH as evidenced by elevated CK-MB fraction has been reported. Little published data exist on the value of cTnI measurements in aneurysmal SAH. METHODS: Thirty-nine patients were studied for seven days. Clinical cardiovascular assessment, electrocardiographic (ECG), echocardiography, cTnI, CK, CK-MB and CK-MB index, myoglobin and 24-h urinary catecholamine assays were performed in all patients. The ECG abnormalities were defined by the presence of ST-T changes, prolonged QT intervals, and arrhythmias. An abnormal echocardiogram was defined by the presence of wall-motion abnormalities and a reduced ejection fraction. The severity of SAH was graded clinically and radiologically. RESULTS: Eight patients demonstrated elevations in cTnI (upper limit of normal is 0.1 microg/liter with the immunoenzymatic assay and 0.4 microg/liter with the sandwich immunoassay), while five had abnormal CK-MB levels (upper limit of normal is 8 microg/liter). Patients with more severe grades of SAH were more likely to develop a cTnI leak (p < 0.05). Patients with cTnI elevations were more likely to demonstrate ECG abnormalities (p < 0.01) and manifest clinical myocardial dysfunction (p < 0.01) as evidenced by the presence of a gallop rhythm on auscultation and clinical or radiological evidence of pulmonary edema as compared to those with CK-MB elevations. The sensitivity and specificity of cTnI to predict myocardial dysfunction were 100% and 91%, respectively, whereas the corresponding figures for CK-MB were 60% and 94%, respectively. Elevations in myoglobin levels (upper limit of normal <70 microg/liter) and urinary catecholamine metabolites (urinary vanilmandelate/creatinine ratio upper limit of normal, 2.6) are a nonspecific finding. CONCLUSIONS: Measurements of cTnI reveal a higher incidence of myocardial injury than predicted by CK-MB in aneurysmal SAH, and elevations of cTnI are associated with a higher incidence of myocardial dysfunction. Thus, cTnI is a highly sensitive and specific indicator of myocardial dysfunction in aneurysmal SAH.

Adult↗
PubMed2000

Tenoxicam i.v. in major gynaecological surgery--pharmacokinetic, pain relief and haematological effects.

This study compared postoperative analgesic dispensation and measures relating to haemostasis following intravenous administration, in a randomized double-blinded manner, of either placebo or tenoxicam 20 mg to 30 women presenting for major gynaecological oncology surgery under a standardized, combined epidural/general anaesthetic technique. Pharmacokinetic disposition of tenoxicam in this patient cohort was also described. There was no objective or subjective alteration in haemostatic function or increase in blood loss, nor any deviation from the normal range of values. Postoperative analgesia during the first 48 hours was delivered to achieve a VAS endpoint of less than five on leg-raising, by a combination of a nurse-controlled low-dose background epidural infusion and patient-administered epidural bolus. Greater VAS variability was observed during the first four postoperative hours (P = 0.08). The tenoxicam group self-administered significantly fewer epidural bolus doses to maintain satisfactory analgesia compared with the placebo group during the first 24 hours (P = 0.004) and 48 hours (P = 0.01) postoperatively. Similar differences between the groups in the total dose of the epidural bupivacaine/fentanyl mixture delivered were described (4 h: P = 0.148; 24 h: P = 0.033; 48 h: P = 0.001) (Figure 2). Despite surgery, transfusion and the use of a renal protective fluid administration strategy, tenoxicam disposition was not greatly different from that widely described for healthy volunteers. There were no significant side-effects and no adverse events attributable to tenoxicam. In this small study we have shown that tenoxicam administered preoperatively reduced the epidural analgesic requirements during the first 48 hours following major gynaecological surgery. There was no clinical or pathological evidence of haematological impairment following a single i.v. administration of tenoxicam 20 mg.

Aged↗
PubMed2000

Tenoxicam i.v. for major gynaecological surgery--effects on renal function.

Thirty women presenting for major gynaecological oncology surgery under a standardized, combined epidural/general anaesthetic technique received either placebo or tenoxicam 20 mg intravenously, in a randomized double-blinded manner prior to surgery. Plasma and urinary electrolytes, creatinine, prostaglandins PgE2 and PgF1 alpha, and thromboxane (TxB2) were collected 12 hours preoperatively and then for four days postoperatively. There were no significant differences in any of the measured parameters between the groups, at any of the measurement times. Mean (SD) creatinine clearance at baseline, 24 h and 48 h was 100.4 (29.7) and 86.9 (27.5), 128.1 (45.9) and 115.0 (40.3), 137.5 (50.7) and 121.6 (38.6) in the placebo and tenoxicam groups respectively (P = 0.28). Both groups required similar amounts of intraoperative ephedrine and intravenous fluids to maintain blood pressure. The minimal changes in plasma and renal parameters reflect predictable responses to major surgery and rehydration rather than any response to cyclooxygenase inhibition. This may underscore the importance of maintenance of blood pressure during the course of surgery and postoperative care, and perhaps the usefulness of a fluid loading regimen to preserve renal function during surgery. The predicted attenuation of renal prostaglandin-mediated protective mechanisms and enhancement of the catecholamine-mediated renal vasoconstriction by the use of a single 20 mg dose of tenoxicam in this study were not seen. Modulation of renal concentrating mechanisms or excretion of sodium and potassium by tenoxicam was not apparent and a large increase in study size would be required to detect a significant difference in these parameters as a consequence of the drug, over and above any changes in response to surgery and epidural anaesthesia.

Aged↗
PubMed1997

Motor power pharmacodynamics of subarachnoid hyperbaric 5% lidocaine in the sitting position.

BACKGROUND: Repetitive dynamometric measurement using a plantar flexion power device (PFPD) provides detailed data describing the onset and offset of motor block following spinal administration of lidocaine. The aim of this study was to evaluate administration of two doses of spinal lidocaine in the sitting position to determine whether our dynamometric model produces data consistent with our current understanding of the pharmacokinetics of subarachnoid, hyperbaric, 5% lidocaine. METHODS: Twenty male patients (54 to 80 yr) undergoing cystoscopy received spinal anaesthesia with either 75 mg (n = 10) or 100 mg of hyperbaric lidocaine 5%, in the sitting position, under standardised conditions. Plantar flexion muscle power was recorded during onset and offset of anaesthesia using a load cell interfaced with a computer (PFPD). RESULTS: Onset of paralysis following spinal block in the sitting position was rapid and complete with motor power declining exponentially to 5% of preoperative values by 8.5 min in all patients. There was no difference in decay or recovery of plantar flexion motor power data between dosage groups in the sitting position. Measurement using the PFPD shows that onset of motor paralysis is described by an exponential decay and that motor recovery occurs at a fixed rate. Extent of block to cold and pinprick was similar in both dosage groups in the sitting position (median T4). CONCLUSION: This study shows that in the sitting position, doses less than 75 mg of 5% hyperbaric lidocaine are required to significantly improve ambulatory times.

Aged↗
PubMed1990

Adenosine for paroxysmal supraventricular tachycardia: dose ranging and comparison with verapamil. Assessment in placebo-controlled, multicenter trials. The Adenosine for PSVT Study Group.

OBJECTIVE: To assess the safety and efficacy of intravenous adenosine in terminating acute episodes of paroxysmal supraventricular tachycardia. DESIGN: Two prospective, double-blind, randomized, placebo-controlled trials to evaluate dose response in patients receiving adenosine and to compare the effects of adenosine with those of verapamil. PATIENTS: A total of 359 patients with a tachycardia electrocardiographically consistent with paroxysmal supraventricular tachycardia were entered into the two protocols. Patients subsequently found to have arrhythmias other than paroxysmal supraventricular tachycardia were excluded from the efficacy analysis. INTERVENTIONS: The first protocol compared sequential intravenous bolus doses of 3, 6, 9, and 12 mg of adenosine to equal volumes of saline. In the second protocol, patients received either 6 mg and, if necessary, 12 mg of adenosine or 5 mg and, if necessary, 7.5 mg of verapamil. MEASUREMENTS AND MAIN RESULTS: When data are expressed in terms of cumulative response in eligible patients, intravenous adenosine terminated acute episodes of paroxysmal supraventricular tachycardia in 35.2%, 62.3%, 80.2%, and 91.4% of patients who received maximum doses of 3, 6, 9, and 12 mg, respectively, in a four-dose sequence, whereas 8.9%, 10.7%, 14.3%, and 16.1% of patients responded to four sequential placebo doses (P less than 0.0001). In the second trial, cumulative response rates after 6 mg followed, if necessary, by 12 mg of adenosine were 57.4% and 93.4%, and after 5 mg followed, if necessary, by 7.5 mg of verapamil were 81.3% and 91.4%. The average time after injection to termination of tachycardia by adenosine was 30 seconds. Adenosine caused adverse effects in 36% of patients, but they lasted less than 1 minute and were usually mild. CONCLUSIONS: Adenosine in graded doses up to 12 mg rapidly and effectively terminates acute episodes of paroxysmal supraventricular tachycardia in which the atrioventricular node is an integral part of the re-entrant circuit. The overall efficacy of adenosine is similar to that of verapamil, but its onset of action is more rapid. Adverse reactions to adenosine are common but are minor and brief.

Acute Disease↗
PubMed1986

Soft tissue trauma.

With any soft tissue injury that involves a great deal of skin loss, the basic goals of therapy are edema control and management of scar tissue. The key to treatment is early intervention with the use of elevation, exercise, pressure, and splinting to prevent the all too frequent soft tissue and joint contractures. Management is not short-term as maturation of the scar can take up to 1 year. Experienced evaluation and consistency in carrying out the therapeutic program are necessary if full function is to be restored.

Adolescent↗
PubMed1979

Gas-liquid chromatographic-mass spectrometric determination of alpha- and beta-naphthylamines in FD&C Red No. 2 (amaranth).

A method is described for the simultaneous quantitation of trace amounts of alpha- (alpha-NA) and beta-naphthylamines (beta-NA) with detectability in the 0.1 ppb range and sensitivity of 50 picomoles in certified food grade amaranth (FD&C Red No. 2; C.I. Food Red 9; CI 16185). The amaranth sample is extracted with benzene, and the evoporated residue is derivatized with perfluorooctanoic anhydride. The resulting derivatives are separated by gas-liquid chromatography and identified and quantitated by mass spectrometric monitoring of the m/e at 539.04. The method was used for quantitation of alpha-NA and beta-NA in randomly chosen samples of amaranth. Of 11 samples from different manufacturers, 5 were free of the beta-isomer; the remaining samples contained up to 1.2 ppb beta-NA. The concentration of alpha-NA ranged from no detectable amount to 970 ppb; the majority of the samples contained less than 7 ppb.

1-Naphthylamine↗
PubMed1977

N-Nitrosodiethanolamine in synthetic cutting fluids: a part-per-hundred impurity.

N-nitrosodiethanolamine has been found to be present at a concentration of 0.02 to 3 percent in several brands of synthetic cutting fluids. Its identity was confirmed by three independent techniques: (i) by measuring the retention times on two different high-performance liquid-chromatography columns, (ii) by dehydration to N-nitrosomorpholine, and (iii) by preparation of the O-methyl ether derivative.

Environmental Pollutants↗
PubMed1977

Implications of inorganic/organic interconversion on fluxes of arsenic in marine food webs.

An organic form of arsenic is commonly encountered in marine organisms; in greysole and shrimp, it accounted for all arsenic found in muscle tissue. It has been isolated from flounder tissue by two independent procedures; it was hydrophilic, cationic, and was not decomposed to inorganic arsenic by hot nitric and sulfuric acids. NMR spectroscopy indicated all nonexchangeable protons to be equivalent; they behaved more like N-methyl protons than As-methyl protons. High-resolution mass spectroscopy from a heated probe yielded a spectrum corresponding to tetramethylarsonium (AsMe4+); the authentic ion, however, had TLC and ion-exchange behavior different from that of the natural product. Infrared spectrometry likewise produced conflicting or uninterpretable data. Decomposition of the compound for analytical purposes was accomplished by dry ashing under oxidizing conditions. Sea urchins, like trout, converted arsenic to an organic form, but to a more limited degree. Arsenic found naturally in sea urchins and in a species of macroalga was also organic. In individual containers, sea urchins were fed on the alga for 7 weeks. During this time they consumed 0.203 +/- 0.075 mg total As and excreted only 0.036 +/- 0.015 mg as feces. Measurement of inorganic As in the seawater did not account for the discrepancy, but measurements of total As did (0.202 +/- 0.095 mg). Sea urchins, like humans, appear to be able to rapidly excrete these organic forms of arsenic.

Animals↗