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Biomedical subjects

L Alexander

Publications and source records attributed to L Alexander.

At least 19 recordsLinked to original sources
PubMed1992

Analysis of deaths in patients with an implantable cardioverter defibrillator.

The cause of death and clinical characteristics of 26 patients that died after implantable cardioverter defibrillator placement were reviewed and compared to the 145 patients still living after a mean follow-up of 17 months. Operative mortality was 4% (7/171) and resulted from postoperative ventricular arrhythmias (four patients), heart failure (two patients), and respiratory failure (one patient). Operative mortality was significantly higher (1.7% vs 9.6%, P less than 0.05) following concomitant surgical procedures. Total late mortality was 11% (18/171). Thirteen deaths (75%) occurred in-hospital from progressive deterioration of left ventricular function (nine patients), arrhythmia (two patients), and noncardiac causes (two patients). Outpatient mortality was 3.5% (6/171) and resulted from presumed sudden cardiac death in five of six patients; two of the five had devices that were inactive, one had high defibrillation thresholds, and two had suspected bradyarrhythmic deaths. One postoperative death and one late in-hospital death were also considered sudden cardiac deaths for a total of seven patients with defibrillation system failures. By multivariant analysis, preoperative clinical characteristics associated with a worse prognosis following defibrillator implantation were identified: presentation as ventricular tachycardia (P less than 0.02), induction of sustained monomorphic ventricular tachycardia (P less than 0.05), poor left ventricular performance (P less than 0.01), poor functional status (P less than 0.001), and the use of diuretics (P less than 0.01). Frequent device discharges (P less than 0.001) and concomitant antitachycardia pacing systems (P less than 0.001) were markers for greater arrhythmia recurrence and were potent predictors of a worse prognosis and particularly sudden death.

Arrhythmias, Cardiac↗
PubMed1992

Oesophageal propulsive force and its relation to manometric pressure.

A fixed volume capsule incorporating a force transducer and a side hole for manometric measurements was constructed and calibrated. Simultaneous measurements of the propulsive (aboral) force and the manometric pressure (intraluminal pressure) were made at 5, 10, and 15 cm above the lower oesophageal sphincter and in response to dry and wet (5, 10, and 15 ml) swallows. The propulsive force and manometric pressure waves had a simultaneous onset and were of similar duration. Peak values of propulsive force for wet swallows increased significantly as measurements were made progressively more distally within the oesophagus and were greatest in the distal oesophagus. The association between manometric pressure and propulsive force is not strong (r = 0.61) suggesting that intraluminal pressure is a poor predictor of propulsive force and hence an unreliable measure of oesophageal 'function'.

Adult↗
PubMed1991

The power of the therapeutic relationship.

A review of the psychotherapy research literature of the last decade shows that considerable advances of clinical significance have been made toward defining and measuring components of the treatment relationship. The relevance of the therapeutic alliance for predicting outcome in diverse models of treatment is emphasized, and the implications of the findings for clinical training, practice, and research are discussed.

Adaptation, Psychological↗
PubMed1991

Production of the mouse whey acidic protein in transgenic pigs during lactation.

The mouse whey acidic protein (WAP) gene was introduced into the genome of pigs and its expression was analyzed in the mammary gland. Mouse WAP was detected in milk of lactating females from five lines at levels between .5 and 1.5 g/liter, thereby representing as much as 2% of the total milk proteins. The corresponding mRNA was expressed in mammary tissue at levels similar to those of pig beta-lactoglobulin and beta-casein. The pattern of WAP secretion in three pigs over a period of 6 wk was quantitatively similar to that of pig beta-lactoglobulin. From the eight transgenic pigs analyzed, three successfully completed one lactational period, but five pigs stopped lactating a few days after parturition. Our results show that it is possible to produce large quantities of a foreign protein in milk of pigs over a full lactational period. However, expression of WAP can compromise the mammary gland and render it nonfunctional.

Animals↗
PubMed1990

Transcriptional regulation of the murine TSH subunit genes.

These studies have demonstrated that the murine TSH subunit genes are sensitively regulated by thyroid hormone. The T3 receptor complex interacts with both the TSH beta and alpha-subunit gene either in or near the 5' flanking region in close proximity to the transcriptional start sites. This interaction interrupts transcription from the start sites, thus decreasing transcription of the two genes. As a result steady state mRNA levels of both TSH beta and alpha-subunit genes are decreased in the cytoplasm of thyrotropic cells. This series of interactions explains most of the effects of T3 on TSH biosynthesis.

Animals↗
PubMed1989

Chromatographic separations of serum proteins on immobilized metal ion stationary phases.

The separation of proteins on stationary phases consisting of a bound organic chelator and a chelated divalent transition metal has been studied as a function of (A) metal ion species; (B) mobile phase composition and pH; and (C) anion and cation concentration. Optimum separation was observed at alkaline pH on chelated nickel stationary phases. Ammonium and Tris salts reduced the affinity of the metal chelate packing for serum proteins. Halide ions caused the proteins to be more strongly bound to the stationary phase. High salt concentrations had only a small effect on the binding of serum proteins in the absence of amine containing buffers or salts. It was also observed that the ease of elution and the recovery of protein were dependent on pH and upon the presence of halides. The general order of elution of serum proteins, based on isoelectric focusing, was independent of metal ion species and elution conditions, suggesting that a single mechanism or a unique sequence of mechanisms was operative. The results suggest that ligand exchange is the major mechanism of separation under basic conditions and that hydrophobic effects are the result of the competition of nonnitrogen ions with ammonium ions or amines for ligand binding sites modifying or participating in protein binding. Protein binding studies under weak acidic conditions are also presented although the mechanism responsible for protein binding is unclear.

Blood Protein Electrophoresis↗
PubMed1989

Ibuprofen, acetaminophen, and placebo treatment of febrile children.

A double-blind, parallel-group, triple-dummy-designed, single-oral-dose study compared the efficacy, tolerability, safety, and dose-response of 5 mg/kg (n = 32) and 10 mg/kg (n = 28) ibuprofen suspension, 10 mg/kg acetaminophen elixir (n = 33), and placebo liquids (n = 34) in 127 children (2 to 11 years of age) with fever (101 degrees to 104 degrees F). Blood samples, oral temperatures, pulse, blood pressure, and respiration were obtained before and 1/2, 1, 2, 3, 4, 5, 6, and 8 hours after the dose was administered. The study was terminated early if oral temperature was greater than 104 degrees F or if it increased 1 degree F above baseline. All agents were well tolerated and more effective than placebo (p less than 0.05) for fever control. Ibuprofen, 10 mg/kg, was favored over 10 mg/kg acetaminophen (p less than 0.05). For temperatures greater than 102.5 degrees F, a dose-response relationship for 5 and 10 mg/kg ibuprofen was demonstrated in terms of percentage of fever reduction and in terms of the initial 2-hour rate of decrease in temperature. Antipyretic efficacy for temperatures greater than 102.5 degrees F was 10 mg/kg ibuprofen greater than 5 mg/kg greater than 10 mg/kg acetaminophen greater than placebo. All treatments were well tolerated. No significant clinical or laboratory abnormalities were noted. Ibuprofen suspension may be a safe and effective antipyretic in children.

Acetaminophen↗
PubMed1986

The effects of diabetes mellitus, exercise, and single doses of biguanides upon lactate metabolism in man.

The polymorphism of phenformin oxidation has been investigated in 103 non-insulin-dependent (Type II) diabetics. The frequency distribution was clearly bimodal and 14 poor metabolisers were identified. The frequency of the recessive allele (0.369) was not significantly different from that found previously in non-diabetics. Six of the extensive metabolisers of phenformin were matched for age, sex and oxidizer phenotype with non-diabetic controls. All subjects underwent a standard 3-min exercise test, using a bicycle ergometer, after which plasma lactate concentration was monitored for 90 min. There was no significant difference between groups in lactate accumulation or elimination. Ten extensive metabolisers, ten poor metabolisers and seven non-diabetics (matched for age, sex and phenotype with seven of the diabetic extensive metabolisers) were challenged with a fasting oral dose of phenformin (50 mg), after which plasma lactate, and blood pyruvate and glucose concentrations were monitored for 4 h. A further ten diabetics (five extensive and five poor metabolisers of phenformin) received a single dose of metformin (1 g) following an identical protocol. No significant changes were observed in any group.

Adult↗
PubMed1986

Acoustic emission cochleography--practical aspects.

Otoacoustic emissions are discussed as a means of objectively examining cochlear status. Practical uses of otoacoustic emission recording are reviewed, and the technical requirements of a clinical test are discussed. Details are given of an advanced cochlear echo test procedure, and results from normal and hearing impaired ears are discussed. Finally the alternative technique of distortion product analysis is discussed and results are given.

Biomechanical Phenomena↗
PubMed1985

Ornithodoros coriaceus (pajaroello tick) as a vector of bluetongue virus.

Preliminary studies demonstrated that the argasid tick, Ornithodoros coriaceus Koch, could become infected with bluetongue virus (BTV). Ticks became infected after feeding through artificial membranes on BTV-infected suspensions of cell cultures, chicken embryos, and sheep blood. Ticks also became infected after natural feeding on viremic sheep (BTV serotype 17) and cattle (BTV serotype 11). Virus was recovered from the hemolymph and salivary glands of ticks which had ingested BTV either through an artificial membrane or by natural feeding on a host animal. Ticks infected with BTV serotype 13 were capable of transmitting the virus to a susceptible cow at 42 days after ingestion of virus-infected cultures, thus demonstrating the potential of the tick to serve as a biological vector of BTV.

Animals↗
PubMed1979

Unusual leiomyoblastoma of the stomach.

Only about 250 cases of benign gastric leiomyoblastoma of the stomach have been reported. Most occur in the smooth muscle of the antrum, and may be intramural, intraluminal, or exogastric in position. A pedunculated gastric leiomyoblastoma occurs less frequently, and those containing radiographically identifiable calcifications are extremely rare.

Aged↗
PubMed1979

Long-term survival in a case of stage IV carcinoma of the ovary treated with a single chemotherapeutic agent.

A case of stage IV carcinoma of the ovary is presented which was treated approximately six years ago in the Department of Radiation Therapy at Queens Hospital Center. On September 12, 1972, the patient had a total abdominal hysterectomy and bilateral salpingo-oophorectomy for a papillary scirrhous cystadenocarcinoma of the left ovary. At the time of the operation, the patient was found to have stage IV carcinoma of the ovary due to metastases of the liver and rectum. She was scheduled to receive pelvic-abdominal postoperative radiation therapy via the moving strip technique. Unfortunately, after completion of two strips, the patient could not tolerate treatment. She then began chemotherapy with a single agent, chlorambucil.Chlorambucil, 0.2 mg/kg/day×25 days/course was administered. The patient received 18 courses. Treatment dosage on a few occasions was decreased and increased again, due to drops in hemoglobin level and white blood cell and platelet counts. At the time of this presentation, the patient has no signs or symptoms of the disease. The introduction of megavoltage radiotherapy and adjuvant chemotherapy postoperatively has significantly improved the prognosis for patients with ovarian carcinoma. However, despite progress in radiotherapy, some patients cannot sustain this kind of treatment due to the unwanted side effects. Such was the case in this patient. She was switched to chemotherapy with excellent results in response and survival, even cure.

Adenocarcinoma, Scirrhous↗