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Biomedical subjects

J T Stewart

Publications and source records attributed to J T Stewart.

At least 91 records · Page 5Linked to original sources
PubMed1995

Management of behavior problems in the demented patient.

Behavior problems are common in persons with dementia and often lead to caregiver stress and institutionalization for the patient. In most cases, however, these problems are amenable to treatment. Although drug therapy may be necessary to manage some behavior problems, nonpharmacologic strategies may work as well, if not better, with fewer adverse effects. Support and education for the patient's family are the cornerstone of management. At some point, most demented patients display agitation. Appropriate, often nonpharmacologic management of agitation may include establishing a "no-fail" environment, limiting goals and providing reassurance. While delusions and hallucinations are also common, they seldom lead to agitation. Sleep disturbance and wandering are particularly upsetting to the patient's family, but these problems often respond to nonpharmacologic strategies, such as restricting naps and providing more cues about time and place. Depression, which occurs in many demented patients, is an especially treatable cause of disability.

Alzheimer Disease↗
PubMed1994

High-performance thin-layer chromatographic determination of digoxin and related compounds, digoxigenin bisdigitoxoside and gitoxin, in digoxin drug substance and tablets.

A high-performance thin-layer chromatographic (HPTLC) method for the determination of digoxin and its related compounds digoxigenin bisdigitoxoside (DBD) and gitoxin in digoxin drug substance and tablets was developed. Separation of the three compounds was accomplished on a C18 wettable reversed-phase plate using water-methanol-ethyl acetate (50:48:2, v/v/v) as the mobile phase. The analytes were determined by densitometry using absorbance for digoxin and fluorescence for the two related compounds. All peaks were quantified by peak-height analysis. Linear regression analysis of the data was performed for all three compounds. The calibration range for digoxin was set at 320-480 ng per 5-mm band, equivalent to 80-120% (w/w) of a 400-ng band load, that for DBD was set at 4-12 ng per 5-mm band, equivalent to 1-3% (w/w) of the digoxin load, and that for gitoxin was set at 0.4-1.6 ng per 5-mm band, equivalent to 0.1-0.4% (w/w) of the digoxin load. The limit of quantification (LOQ) for digoxin was 64 ng per 5-mm band with a limit of detection (LOD) of 8 ng per 5-mm band. The LOQs for both DBD and gitoxin were 0.12 ng per 5-mm band with LODs of 0.4 ng per 5-mm band. The linearity range for the digoxin peak height in the absorbance mode was 0-5000 ng per 5-mm band. The linearity range for DBD and gitoxin peak heights in the fluorescence mode was 0-2000 ng per 5-mm band.

Carbohydrate Sequence↗
PubMed1994

Management of arrhythmias in hypertrophic cardiomyopathy.

In the management of hypertrophic cardiomyopathy the goals should be the control of symptoms, and the identification and treatment of those at high risk. Arrhythmias, particularly atrial fibrillation and nonsustained ventricular tachycardia, are common in adult patients with hypertrophic cardiomyopathy. Atrial fibrillation has long been thought to herald an ominous prognosis, but this is probably not the case, and in the majority of patients atrial fibrillation can be controlled without accelerated symptomatic deterioration. Uncontrolled observations indicate that low-dose amiodarone may be the most useful drug in both paroxysmal and chronic atrial fibrillation. The detection of nonsustained ventricular tachycardia on ambulatory ECG monitoring remains the single most useful indicator of the risk of sudden death in the adult patient, and the treatment of choice is again low-dose amiodarone. The mechanism of sudden death, and the mode of action of amiodarone in preventing it, are not known for certain in the majority of patients. The risk of sudden death is higher in children and adolescents, but arrhythmias are less common, and no useful predictive marker of increased risk has been found. The roles of invasive electrophysiological studies and the implantable cardioverter-defibrillator are still being evaluated.

Arrhythmias, Cardiac↗
PubMed1994

Chromatographic analysis of selected tetracyclines from dosage forms and bulk drug substance using polymeric columns with acidic mobile phases.

The LC analysis of selected tetracyclines from dosage forms and bulk drug substance using polymeric columns has been studied. Mobile phases containing acetonitrile-0.02 M sodium perchlorate (pH 2.0) were used. The tetracyclines were detected by their absorbance at 280 nm. The columns included: a polystyrene-divinylbenzene (PS-DVB) column and a polymethacrylate column with octadecyl ligands (PM-C18). Performance of the two columns was compared and applicability of the described methods for compendial use has been evaluated. The tetracyclines investigated include: minocycline, oxytetracycline, tetracycline, demeclocycline, chlortetracycline, methacycline, doxycycline and meclocycline.

Acetonitriles↗
PubMed1994

Stability of cefmetazole-doxycycline mixtures in sodium chloride and dextrose injections.

This study involved the mixing of cefmetazole 1 and 2 Gm with doxycycline 100 and 200 mg, in sodium chloride and dextrose injections. The mixtures were stored either at ambient temperature for 96 h or at 4 degrees C for 168 h followed by 8 h at ambient temperature. HPLC assay of both cefmetazole and doxycycline levels were performed at prescribed sampling times. Cefmetazole 1 Gm in doxycycline 100 and 200 mg mixtures, in sodium chloride injection was not stable up to 4 h, but cefmetazole 2 Gm in doxycycline 100 and 200 mg mixtures, in sodium chloride injection was stable for up to 24 h. The cefmetazole controls were stable for 72 h in sodium chloride injection. Cefmetazole 1 Gm with doxycycline 100 mg, in dextrose injection was stable up to 72 h. The 2 Gm cefmetazole and 100 mg doxycycline mixture in dextrose injection was stable for 96 h. Cefmetazole 1 Gm and doxycycline 200 mg in dextrose injection was stable up to 96 h, but the 2 Gm cefmetazole-200 mg doxycycline mixture was only stable for 72 h. Cefmetazole controls in dextrose injection were stable for 24 h. Doxycycline 100 and 200 mg were stable with cefmetazole 1 and 2 Gm, in both sodium chloride and dextrose injections for 96 h at ambient temperature. Doxycycline control solutions were also stable for 96 h. Cefmetazole 1 and 2 Gm and doxycycline 100 and 200 mg were generally stable in both sodium chloride and dextrose injections at 4 degrees C for 168 h, and at ambient temperature for 8 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Cefmetazole↗
PubMed1993

High-performance liquid chromatographic separation of ondansetron enantiomers in serum using a cellulose-derivatized stationary phase and solid-phase extraction.

R(-)-Ondansetron and S(+)-ondansetron in human serum were resolved and quantified using a stereospecific HPLC method. Each enantiomer and the internal standard prazosin were isolated from serum using a solid-phase extraction procedure on a cyanopropyl column. Recoveries of 97, 96 and 88% were obtained for the R(-)-enantiomer, the S(+)-enantiomer, and the internal standard, respectively. A cellulose-based chiral analytical column (Chiralcel OD) was used with a mobile phase consisting of hexane-95% ethanol-2-propanol-acetonitrile (65:25:10:1, v/v). Linear calibration curves were obtained for each enantiomer in serum in the concentration range 10-200 ng/ml. The limit of quantitation of each enantiomer was 10 ng/ml. The detection limit for each enantiomer in serum using UV detection at 216 nm was 2.5 ng/ml (signal-to-noise ratio of 3).

Cellulose↗
PubMed1993

Separation of tetracyclines by liquid chromatography with acidic mobile phases and polymeric columns.

The LC separation of selected tetracyclines has been studied using polymeric columns. Mobile phases containing acetonitrile-0.02 M sodium perchlorate, pH 2.0, were used. Asymmetry factor and number of theoretical plates were calculated for the tetracyclines investigated on four polymeric columns. The columns included: two polystyrene-divinylbenzene (PS-DVB) copolymeric columns, a PS-DVB column with octadecyl ligands and a polymethacrylate column with octadecyl ligands (PM-C18). The PLRP-S (PS-DVB) column and the PM-C18 column were found to be the most suitable for the analysis of the selected tetracyclines. Resolutions between pairs of selected tetracyclines were calculated and compared for the latter two columns, with the PLRP-S (PS-DVB) columns showing the best results. The PM-C18 column has the advantage of allowing the use of higher flow rates, which minimized analysis times. The tetracyclines included minocycline, oxytetracycline, tetracycline, demeclocycline, chlortetracycline, methacycline, doxycycline and meclocycline. Representative degradation products and impurities for selected tetracyclines were also included.

Chromatography, High Pressure Liquid↗
PubMed1993

Percutaneous transluminal coronary angioplasty in chronic coronary artery occlusion.

OBJECTIVES: This study was conducted to determine the procedural success rate, complication rate and long-term outcome of percutaneous transluminal coronary angioplasty in chronically occluded coronary arteries. BACKGROUND: Coronary angioplasty of chronically occluded vessels has a lower success rate than has angioplasty of nonoccluded vessels, but it is frequently considered safe because the target vessel is already occluded. The purpose of this study was to determine the reliability of these assumptions at our institution, with the objectives stated above. METHODS: We identified from the angioplasty data base at our institution 100 consecutive coronary angioplasty procedures performed between 1987 and 1991 for chronic total occlusion, defined as complete occlusion (Thrombolysis in Myocardial Infarction [TIMI] grades 0 and 1 flow) for > or = 3 months. The records of the 95 patients who underwent these procedures were reviewed to determine procedural outcome and medium-term results. RESULTS: Procedural success was obtained in 47 occluded vessels (47%). Significantly fewer successes were obtained in the right coronary artery (26.8%) than in either the left anterior descending (57.1%) or the left circumflex (45%) coronary artery (p < 0.05). A procedural failure without serious adverse consequences occurred in 45 procedures (45%), but in eight patients (right coronary artery in five, left anterior descending artery in three) attempted recanalization was complicated by extensive coronary dissection with acute myocardial ischemia, and one of these patients died. There were no emergency operations, but elective coronary artery bypass surgery was undertaken in 26 patients (in 3 after extensive dissection, in 7 after an apparently good result and in 16 in whom the procedure failed). At 12 months after the procedure, 64.1% of those with a procedural success were event free compared with 32.6% of those whose procedure was both unsuccessful and uncomplicated (p < 0.025) and 25% of those in whom it was unsuccessful and complicated by coronary dissection (p < 0.025). CONCLUSIONS: In this series of recanalization of chronically occluded coronary arteries, there was a low procedural success rate, particularly for the right coronary artery. However, when procedural success was obtained, the long-term outlook was good. The overall risk of coronary dissection was comparable to the risk in nonoccluded vessels but was particularly high in the right coronary artery (13%).

Adult↗
PubMed1993

Differential protein binding of ceftizoxime in cord versus maternal serum.

Ceftizoxime concentrations are higher in cord blood and amniotic fluid than in maternal blood. More avid binding to fetal serum proteins is a suggested mechanism. We measured ceftizoxime protein binding in fetal and maternal blood and documented significantly less protein binding to fetal proteins (21.9% vs 57.8%).

Amniotic Fluid↗
PubMed1993

Left ventricular energetics: heat production by the human heart.

OBJECTIVE: The aim was to examine the effect of coronary artery disease on human left ventricular energetics by a comparison of left ventricular oxygen consumption and heat production. The usefulness of measurement of left ventricular heat production for the detection of the expected change in left ventricular energetics produced by atrial pacing to a faster heart rate was also assessed. METHODS: Forty six patients (mean age 57 years; 31 men) undergoing cardiac catheterisation and coronary arteriography for the investigation of chest pain were studied. Normal left ventricular function and normal coronary arteries were present in eight and 38 had atheromatous coronary artery disease. Left ventricular heat production was calculated from coronary blood flow, the coronary arteriovenous (aorta-coronary sinus) temperature difference, and the areas under thermodilution curves recorded in the aorta and coronary sinus after injection of cold saline into the pulmonary artery. Mean external left ventricular power was calculated from mean arterial blood pressure and cardiac output. Left ventricular mechanical efficiency was derived from heat production and the energy value of myocardial oxygen use, assuming aerobic metabolism. In 27 patients studies were repeated during atrial pacing from the coronary sinus. RESULTS: At rest under basal conditions left ventricular heat production was 2.4(SD 1.0) W in patients with normal hearts and 3.1(1.4) W in patients with coronary disease (NS). Mechanical efficiency was 44.2(9.7)% in the normal patients and 30.7(10.9)% in those with coronary disease (p = 0.003). During atrial pacing to a faster heart rate left ventricular energy supply increased from 4.6(2.7) W to 5.9(3.3) W (p < 0.0005), and heat production increased from 3.0(1.6) W to 4.6(2.4) W (p < 0.0005), but mean external power was not altered. As the extra energy used during pacing was "wasted" as heat, there was a significant fall in left ventricular mechanical efficiency with pacing from 33.9(13.5)% to 18.9(15.2)% (p < 0.0005). CONCLUSIONS: These results show the effect of coronary artery disease on the energetics of left ventricular function. They also show that the method and equipment can detect the expected alteration in left ventricular energetics produced by atrial pacing. The measurement of left ventricular heat production and oxygen consumption allows assessment of the total left ventricular energy flux, and may be useful for the evaluation of drug treatment with such as inotropes and vasodilators, and for the investigation of the functional consequences of left ventricular disease.

Adult↗
PubMed1993

Case management in Alzheimer's disease.

Patients with a diagnosis of Alzheimer's disease and their families need the assistance of a case manager to deal with the issues of long-term care. The case manager assists with education, planning, linking to formal and informal resources, and addressing emotional needs in the family unit. This article discusses specific suggestions to address problems in the three stages of Alzheimer's disease from the time of medical diagnosis to the end of life.

Alzheimer Disease↗