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Biomedical subjects

S L Wilson

Publications and source records attributed to S L Wilson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Constructing arousal profiles for vegetative state patients--a preliminary report.

Arousal profiles are a method that we have developed for using data derived from time sampling to examine how behaviours such as the frequency with which the eyes are observed open, and the frequency of spontaneous movements, vary in the periods immediately before and immediately after sensory stimulation treatment. We believe changes in such behaviours reflect changes in arousal. The use of this new technique is illustrated with examples from a pilot study using data from 15-day treatment blocks, gathered for 10-minute periods immediately before and after sensory stimulation treatment from three patients using single-case research methods. The patients were diagnosed as being in vegetative state following traumatic brain injury. The possible significance of the differing characteristics of the profiles is discussed.

Adult↗
PubMed1992

A venous thrombosis technique for experimental thrombolytic therapy.

A technique for the experimental creation of a venous thrombus in the rat is described. This technique involves a circumferential stretching of the intima, which maximizes intraluminal collagen exposure without complete separation of the vessel wall. This thrombotic method was 94.4% effective at complete vessel occlusion after 24 hours in 40 treated veins. This model is of particular interest in the in vivo evaluation of thrombolytic agents in the laboratory setting and as an adjunct to thrombotic complications in microsurgery.

Animals↗
PubMed1991

Flexible sigmoidoscopy screening for asymptomatic colorectal disease in patients with and without inguinal hernia.

Several studies have evaluated the diagnostic value of flexible sigmoidoscopy for screening asymptomatic patients before hernia repair. All have shown a 16% to 28% incidence of neoplastic (malignant or premalignant) lesions. None of these studies compared a similar group of asymptomatic patients without hernia to determine whether the incidence is increased in patients with hernias. We reviewed 87 consecutive cases of male surgical patients without hernia or any anorectal disease who had flexible sigmoidoscopy between June 1986 and December 1989 (group 1) and compared them with a group of hernia patients that we previously reported (group 2). Patients with stool positive for occult blood were excluded from this study. Examinations in both groups were done under the direct supervision of an attending surgeon (W.W., C.S.C., or J.K.). No significant difference was noted between group 1 and group 2 in mean age (mean 65.6 vs 59.7 years), rate of normal findings (68% vs 63%), and incidence of neoplastic lesions (14% vs 22%). All patients tolerated the procedure well, and there were no complications.

Adenoma↗
PubMed1990

Comparison of free and liposome encapsulated doxorubicin tumor drug uptake and antitumor efficacy in the SC115 murine mammary tumor.

Tumor drug uptake and antitumor efficacy of free and liposomal doxorubicin (DOX) were determined in the SC115 Shionogi mouse mammary tumor. Liposomal DOX systems were prepared by pH gradient-driven drug encapsulation in 170 nm egg phosphatidylcholine/cholesterol (55:45, mol ratio) vesicles. Intravenous injection of free DOX at 6.5 mg/kg, the maximum tolerated dose for free drug in the multiple dose therapy regimen, resulted in tumor-associated drug levels of 2.0 micrograms/g tissue at 1 h which remained constant over 24 h. Liposomal DOX injected at 6.5 mg/kg led to an accumulation of drug in the tumor from 2.6 micrograms/g tissue to 5.5 micrograms/g tissue between 1 h and 24 h, respectively. Increasing the dose of liposomal DOX to 13.0 mg/kg increased tumor drug uptake levels to 5.7 micrograms/g and 10.2 micrograms/g tissue at 1 h and 24 h, respectively. Administration of free or liposome encapsulated DOX every 7 days for 3 weeks resulted in a dose-dependent decrease in tumor growth rate. However, liposomal DOX injected at 6.5 mg/kg exhibited enhanced tumor growth inhibition compared to an equivalent dose of free drug. Further, the ability to administer increased doses of the less toxic liposomal DOX not only resulted in a greater inhibition of tumor growth but also significantly reduced tumor weight. Tumors weighing as much as 5 g were diminished to less than 0.5 g upon treatment with liposomal DOX at a dose of 13 mg/kg. In addition, groups receiving the highest liposomal DOX dose exhibited 25% complete tumor regression which persisted over the 50-day study period. These results demonstrate the ability of appropriately designed liposomal DOX systems to significantly enhance the delivery and retention of drug at solid tumor sites, resulting in increased therapeutic activity.

Animals↗
PubMed1989

Identification of a 150-kilodalton polypeptide that copurifies with yeast TFIIIC and binds specifically to tRNA genes.

The transcription in vitro of eucaryotic tRNA genes by RNA polymerase III requires two transcription factors, designated TFIIIB and TFIIIC. One of the critical functions of TFIIIC in the transcription of tRNA genes is that it interacts directly and specifically with the two internal promoter elements of these genes. We have partially purified Saccharomyces cerevisiae TFIIIC by chromatography on Bio-Rex 70, DEAE-cellulose, and phosphocellulose resins. A 150-kilodalton (kDa) DNA-binding polypeptide copurified with TFIIIC activity. This 150-kDa protein coeluted with the DNA-binding activity of TFIIIC after rechromatography of TFIIIC on phosphocellulose and its elution with a linear salt gradient. The stable and high-affinity interaction of this protein with tRNA genes was demonstrated by the maintenance of a protein-DNA complex under conditions of high ionic strength. Finally, we showed by two criteria that the interaction of this protein with tRNA genes was specific. First, the protein-DNA complex was competed with only by DNA-containing tRNA genes; second, the protein preferentially bound to DNA fragments containing a tRNA gene. These results strongly suggest that the DNA-binding domain of the yeast TFIIIC is contained within this 150-kDa polypeptide.

Binding Sites↗
PubMed1989

Utilization of allied health personnel in HMOs.

Health Maintenance Organizations (HMOs) have become a significant component of the health care delivery system and thus provide employment opportunities for allied health professionals. This study investigated the utilization of selected allied health services and personnel in a national sample of HMO settings. Significant utilization of allied health services were reported both through provision of services in-house and through contractual arrangements. Smaller HMOs tended to use several allied health services in-house, while larger HMOs used both in-house and contractual services. Younger HMOs tended to utilize contractual arrangements while older HMOs utilized in-house services. Staff and group HMOs tended to have the highest utilization of health manpower with the larger, older HMOs employing more of those personnel.

Allied Health Personnel↗
PubMed1987

Brain stem evoked response in the assessment of learning disabilities.

Evidence has accumulated rapidly to support the hypothesis that neurological anomalies underlie specific forms of learning disability (LD). This article reviews recent studies directed at the electrophysiological assessment of LD children, with emphasis on the brain stem evoked response(BSER) methodology. Child studies appear to indicate that there are significant differences in BSERs between LD and age-matched normal controls. The methodological and statistical differences among these studies, which have clouded the findings and made replication difficult, are reviewed. Improvements in sampling and empirical procedures are suggested, including the use of discriminant analysis to explore BSER asymmetries in LD children. Future inquiry into the measurement and analysis of BSER activity in LD populations is warranted on the basis of these preliminary findings. New information may bring professionals closer to an understanding of the neurological causes of specific subtypes of LD and permit earlier identification of these "at risk" populations.

Adolescent↗
PubMed1984

Management of ventriculomegaly in the fetus.

We studied 24 human fetuses with cerebral ventriculomegaly by serial obstetric ultrasound to define the natural history of fetal ventricular enlargement and to develop a management strategy. In 10 fetuses, ventriculomegaly was associated with other severe anomalies; nine of these families chose to terminate the pregnancy. In three other severely affected fetuses in whom ventriculomegaly was detected serendipitously late in gestation, routine obstetrical management was performed; none survived. Eleven fetuses had ventriculomegaly without associated severe anomalies. Ventriculomegaly remained stable or of moderate severity throughout gestation in nine, resolved gradually in one, and progressed in one who did not have signs of increased intracranial pressure at birth. All of these fetuses were viable; three patients required shunting in the neonatal period, and two others by 5 months of age. Although obstetric ultrasound usually can detect anomalies associated with fetal ventriculomegaly, three fetuses with isolated ventriculomegaly had midline brain malformations that could not be distinguished in utero from hydrocephalus, even in retrospect. Prenatal diagnosis improves perinatal management by allowing counseling, and selective pregnancy termination, or selection of the timing, mode, and place of delivery to optimize outcome. Most fetuses with ventriculomegaly do not require intervention before birth.

Abnormalities, Multiple↗
PubMed1982

Breathing pattern and transcutaneous oxygen tension during motor activity in preterm infants.

We studied breathing pattern and transcutaneous oxygen tension (TcPO2) during episodes of sustained generalized motor activity in 18 hospitalized preterm infants. We used a newly developed quantitative method for assessing minute ventilation in infants during vigorous motor activity. We recorded respiratory air flow, tidal volume, esophageal pressure, TcPO2, and electromyograms of various muscle groups. We observed a distinctive pattern of breathing ("exertional breathing pattern") that was invariably associated with episodes of "squirming" motor activity. This breathing pattern is characterized by reduced minute volume, intermittent Valsalva maneuvers, and obstructed inspiratory effects (obstructive apnea). Episodes of squirming with the accompanying altered breathing pattern were usually followed by a decrease in TcPO2. These episodes occurred spontaneously or could be induced by sensory stimulation. They appear to be a significant cause of obstructive apnea and TcPO2 instability in hospitalized preterm infants, and were responsible for 30% of sudden decreases in TcP[O2 of 10 mmHg or greater.

Heart Rate↗
PubMed1981

Coordination of breathing and swallowing in human infants.

Spontaneous nonfeeding swallows taken during wakefulness and sleep were identified in nine preterm infants by characteristic patterns in pharyngeal pressure, submental electromyogram, and respiratory airflow. Two hundred and seventeen swallows during ongoing respiration interrupted either inspiratory or expiratory airflow with airway closure for approximately 1 s. The duration of airway closure was independent of respiratory rate. A brief "swallow-breath" was associated with swallow onset in most instances. The respiratory nature of this movement was confirmed by simultaneous recording of a fall in pharyngeal or esophageal pressure and outward movement of the abdomen. Prolongation of the respiratory cycle was generally observed when a swallow interrupted ventilation at higher lung volumes, i.e., in late inspiration or early expiration. When the swallow interrupted ventilation at lower lung volume, i.e, in late expiration or early inspiration, the subsequent inspiratory effort was usually obstructed as it preceded airway opening at the end of the swallow synergism.

Deglutition↗
PubMed1981

Effects of atropine, glycopyrrolate, and cimetidine on gastric secretions in morbidly obese patients.

Gastric volume and pH were studied immediately after induction of anesthesia and endotracheal intubation in 40 morbidly obese patients undergoing gastric bypass procedures. Of 14 patients receiving intramuscular atropine (0.6 mg) preoperatively, 67% had gastric pH values < 2.5; 33% of these patients had both a gastric pH < 2.5 and a volume > 20 ml. When the drug administered was intramuscular glycopyrrolate (0.3 mg), 62% of the patients had gastric pH values > 2.5; 30% had both gastric pH values < 2.5 and volumes > 20 ml. Differences between the two drugs were not significant. Thirteen patients received cimetidine orally at midnight preoperatively and again 2 to 4 hours before the induction of anesthesia. Patients in this group had gastric pH values that were significantly higher than those observed in patients given anticholinergic drugs. Only 15% had gastric pH values < 2.5. Gastric volumes observed in patients receiving cimetidine were not significantly different from those receiving anticholinergic drugs. Whereas only 7.9% of patients receiving cimetidine had both low pH values and gastric volumes > 20 ml, this was not statistically different from the observations made in patients receiving atropine or glycopyrrolate. Despite this, it is concluded that cimetidine administered before the induction of anesthesia in morbidly obese patients may reduce the high risk of aspiration pneumonitis in such patients.

Adult↗
PubMed1980

Hiccups in infants: characteristics and effects on ventilation.

Twenty-seven polygraphic recordings of respiration were obtained on 20 infants, providing data on the frequency, distinguishing features, and medical significance of hiccupping episodes. Eight hiccupping episodes were recorded in seven subjects. The mean duration of the spells was 8.4 +/- 4.2 (SD) minutes. Unintubated subjects, not selected because they were hiccupping, hiccupped 2.5% of the time that they were monitored. Each hiccup was a brief, powerful inspiratory muscle contraction. In unintubated subjects, hiccups were marked by upper airway obstruction, whereas in intubated patients, hiccups were unobstructed inspirations. In unintubated subjects, hiccups were associated with an increase in obstructed eupneic breaths and with decreases in respiratory frequency and minute ventilation; in three subjects hiccups precipitated episodes of mixed apnea. In intubated patients, hiccupping spells were characterized by hyperventilation and respiratory alkalosis. Two types of ECG artifacts were seen with hiccups: high-frequency spikes, mimicking abnormal QRS complexes, and low-frequency waves. From these studies, it appears that hiccups occur frequently in young infants and may affect breathing in clinically significant ways.

Alkalosis, Respiratory↗