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Biomedical subjects

S M Scott

Publications and source records attributed to S M Scott.

At least 19 recordsLinked to original sources
PubMed1995

Electrically stimulated colonic reservoir for total anorectal reconstruction.

Total anorectal reconstruction after abdominoperineal excision of the rectum has failed to achieve perfect continence. Electrically stimulated reservoir evacuation in combination with an electrically stimulated gracilis neoanal sphincter might improve results. A J pouch was constructed in an isolated colonic loop of seven dogs. Bipolar square wave pulses were delivered via two intramural stainless steel electrode pairs at 10 Hz. Stimulation parameters were varied to achieve adequate contraction. Serosal strain gauges recorded spontaneous and stimulated pouch motility. Evacuation was quantified by a volume displacement technique and observed fluoroscopically. Recordings were performed for a median of 3 (range 1-11) months. At 10 Hz and 0.5 ms pulse width, stimulation was required for 2 min and at voltages of 15 V (n = 4), 18 V (n = 1) and 20 V (n = 2) to obtain a contraction of amplitude comparable to that of a spontaneous contraction. Suprathreshold stimulation invariably resulted in colonic pouch contraction. The mean(95 per cent confidence interval (c.i.)) stimulus-response latency was 25.5(1.9) s. The mean(95 per cent c.i.) intraluminal pressure generated during stimulation was 114.1(17.0) cmH2O and 64.6(12.0) cmH2O during spontaneous activity (P < 0.001). In conclusion, electrical stimulation via intramural electrodes produced contraction generating sufficient intraluminal pressure to effect evacuation of a canine colonic pouch. This has potential for incorporation with an electrically stimulated neoanal sphincter in total anorectal reconstruction to improve evacuation and continence.

Animals↗
PubMed1995

Comparison of pediatric end-tidal CO2 measured with nasal/oral cannula circuit and capillary PCO2.

This study was designed to determine whether end-tidal carbon dioxide (ETCO2) values obtained by noninvasive oral/nasal cannula circuit with side-stream capnometry correlate reliably with capillary PCO2 (CapCO2) in a pediatric population without cardiopulmonary problems. Each patient was monitored until a reliable 5-minute ETCO2 waveform was obtained. A capillary blood gas sample was drawn while, simultaneously, ETCO2 was recorded. The difference between CapCO2 and ETCO2 levels was tested with a paired t-test at P < .001. The limits of agreement were established with a 95% confidence level. The stability of the measured difference across the range of mean scores (CapCO2 + ETCO2/2), age, and respiratory rate was tested using simple linear regression. Fifty-eight children (23 girls and 35 boys) had mean ETCO2 readings of 33.96 mm Hg (SD 4.26), and mean CapCO2 readings of 35.93 (SD 4.04). A relative average bias of 1.96 with ETCO2 lower than CapCO2 was established with 95% limits of agreement of +/- 5.2 mm Hg (t = 5.71). Variability of difference scores was not related to range of mean scores (r = .08), age (r = .09), or respiratory rate (r = .25). End-tidal CO2 measured by an oral/nasal cannula capnometry circuit is a noninvasive method of assessing indirect measurements of PCO2 in a normal pediatric population.

Adolescent↗
PubMed1995

Using mortality data to describe geographic variations in health status at sub-district level.

OBJECTIVE: To describe sub-district variations in health status, using mortality data that are processed locally. DESIGN: A descriptive study of routinely collected death registration data, using multicause coding. SETTING: The London Borough of Croydon, with a population of 319,200 divided into 27 electoral wards. SUBJECTS: Deaths of Croydon residents, registered with the Registrar of Births and Deaths, which occurred between January 1990 and December 1992 inclusive. MAIN OUTCOME MEASURES: Variations in life expectancy, all-cause standardised mortality ratios (SMRs), and disease-specific mortality ratios between selected wards. Deaths in nursing homes were excluded to avoid bias. RESULTS: Data from 8,930 death registrations, of which 852 occurred in nursing homes, were analysed by electoral ward. The range for all-cause SMRs, including nursing home deaths, was 153 (139-168) to 66 (58-75). When nursing home deaths were excluded, the SMRs for two wards that were significantly higher than the Croydon average fell into the average range. The range, excluding nursing home deaths, was 133 (113-153) to 71 (62-80). Life expectancy at birth varied from 79.8 years to 74.4 years, and life expectancy at age 65 by three years between wards at the two ends of the spectrum. The geographic distribution of ischaemic heart disease and diabetes showed significant differences. CONCLUSIONS: We contend that death registration data are a useful tool for describing sub-district variations in health status. Deaths of nursing home residents are a source of bias and should be excluded from the analysis. Multicause coding allows a more accurate description of geographic variations in specific diseases, such as ischaemic heart disease and diabetes.

Adolescent↗
PubMed1995

Asymptomatic carotid artery stenosis and stroke in patients undergoing cardiopulmonary bypass.

PURPOSE: This study was undertaken to assess the natural history of carotid artery stenosis in patients undergoing cardiopulmonary bypass (CPB) at a Veterans Administration Medical Center. METHODS: Between January 1989 and August 1993, all patients undergoing CPB were offered preoperative carotid artery ultrasound screening as part of an investigative protocol. Patients were monitored in-hospital for the occurrence of perioperative neurologic deficit. RESULTS: A total of 582 patients underwent carotid artery ultrasound screening. Greater than 50% stenosis or occlusion of one or both internal carotid arteries was present in 130 patients (22%), with 80% or greater stenosis or occlusion of one or both arteries present in 70 patients (12%). In-hospital stroke or death occurred in 12 (2.1%) and 36 (6.2%) patients, respectively. Of the 12 strokes, five were global and seven were hemispheric in distribution. Of the five patients who had global events, none had evidence of carotid artery stenosis. However, of the seven patients who had hemispheric events, five had significant 50% or greater stenosis or occlusion of the internal carotid artery ipsilateral to the hemispheric stroke. Therefore the presence of carotid artery stenosis or occlusion was significantly associated with hemispheric stroke (no stenosis 0.34% vs stenosis 3.8%; p = 0.0072). Furthermore, the risk of hemispheric stroke in patients with unilateral 80% to 99% stenosis, bilateral 50% to 99% stenosis, or unilateral occlusion with contralateral 50% or greater stenosis was 5.3% (4 of 75). No strokes occurred in patients with unilateral 50% to 79% stenosis (n = 52). CONCLUSIONS: It is concluded that carotid atherosclerosis is a risk factor for hemispheric stroke in patients undergoing CPB.

Adult↗
PubMed1995

Prolonged ambulatory canine colonic motility.

Canine gastrointestinal motility is studied at present in animals confined to a small cage or sling. The aims of this study were to record colonic activity over a 24-h period in eight dogs by an ambulatory method. Motility signals from implanted strain gauges were processed and stored via a portable battery-operated amplifier and digital recorder housed in a jacket. Ambulant interdigestive activity was the same as observed in laboratory experiments, with migrating colonic motor complexes (CMCs) and infrequent giant contractions (GCs). Feeding caused a multiphasic alteration in motility for 582.1 +/- 18.1 min (mean +/- SE). There were four distinct phases. During the "early" (0-2 h) postprandial period, phase 1 (mean duration: 55.1 +/- 4.0 min), which was distinguished by CMCs of high frequency and elevated amplitude in the proximal colon, and phase 2 (78.2 +/- 6.2 min), which had CMC characteristics similar to those in the interdigestive period, occurred. Phase 3 (218.8 +/- 13.6 min), a further period of increased motility, and phase 4 (339.1 +/- 14.0 min), characterized by low-amplitude long-duration CMCs, occurred during the "late" (2 h onward) postprandial response. With the exception of phase 3, postprandial phases were not always present following food intake, and their expression was markedly influenced by variations in meal time and by defecation immediately following feeding. Spontaneous defecation was characterized by a variety of motor profiles, with a GC accompanying two-thirds of episodes. We conclude that a more complete picture of canine colonic motility has been documented because of the development of the ambulatory system.

Animals↗
PubMed1995

Effect of gestational age, postnatal age, and illness on plasma cortisol concentrations in premature infants.

The purpose of this study was to define the pattern of postnatal plasma cortisol concentrations during the first week of life in premature infants, and to evaluate the effect of developmental and clinical factors on this pattern. We measured plasma cortisol concentrations in the morning and afternoon on d 2, 4, and 6 in 120 premature infants (gestational age 24-36 wk) and examined the effects of gestational age, postnatal age, and illness. We described an inverse relationship between gestational age and cortisol concentrations, with the youngest infants having the highest random cortisol values (F = 5.14, p = 0.0073). Illness had a significant negative effect such that the cofactors ventilatory support pattern (F = 6.62, p = 0.0016) or "use of surfactant" (F = 6.63, p = 0.001) defined a pattern where cortisol values were lower in infants that had the highest ventilatory requirements or that received surfactant compared with values from those infants who did not have these requirements. The postnatal pattern in cortisol values depended on gestational age. Ill infants more than 27 wk gestational age increased their cortisol values from d 2 to d 6 although cortisol values decreased in well infants. These patterns resulted in a nonsignificant change over time for these age groups. In contrast, cortisol values significantly decreased from d 2 to d 6 in both well and ill infants that were less than or equal to 27 wk. We conclude that plasma cortisol concentrations in the premature infant are significantly correlated with gestational age and to markers of illness.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1995

Dexamethasone therapy is associated with a rise in urinary epidermal growth factor concentrations in the preterm infant.

The effect of glucocorticoid hormones on epidermal growth factor (EGF) concentrations has not been described in the premature infant. We examined this relationship in a group of infants treated with dexamethasone for airway edema (three to five doses) or chronic lung disease (six weeks of a tapering protocol). We collected urinary samples in 45 infants (25 for airway edema, 20 for chronic lung disease) before, during and after the use of dexamethasone. The EGF values were unchanged in infants that were given dexamethasone for airway edema. In contrast, all infants treated for chronic lung disease increased their EGF values by 1 week of therapy. At the end of the dexamethasone taper, ten of the infants had recovered successfully from ventilatory support. This group of infants had post-therapy EGF values that were significantly higher than pretherapy values. In the ten infants that were still ventilator dependent at the end of therapy, EGF values were not different from pretherapy values. We conclude that dexamethasone therapy was associated with an increase in urinary EGF values in the preterm infant treated for at least 1 week. The positive correlation of tapering from ventilatory support with increases in EGF values suggests that EGF may be a marker of dexamethasone effect or an effector of dexamethasone action.

Adrenocorticotropic Hormone↗
PubMed1995

Compartment syndrome in the forearm following fractures of the radial head or neck in children.

A volar compartment syndrome of the forearm was identified following a minimally displaced or angulated fracture of the radial head or neck in three children. The fractures were due to a fall from a bed or from a standing height on an outstretched hand. All three patients had symptoms and signs that were consistent with elevated intracompartmental pressure in the forearm when they were first examined, twelve to twenty-four hours after the injury, and all were managed with an emergency fasciotomy of the forearm. The radial fracture was treated without reduction in the first patient, with manipulative closed reduction in the second patient, and with open reduction and stabilization with Kirschner wires in the third patient. All three patients had a full functional recovery.

Child↗
PubMed1995

Evidence of early adrenal insufficiency in babies who develop bronchopulmonary dysplasia.

OBJECTIVES: To test the cortisol response to adrenocorticotrophic hormone (ACTH) in a population of very low birth weight newborns at the end of the first week of life, and to evaluate the relationship of this response to the subsequent development of bronchopulmonary dysplasia and to the total length of oxygen dependence. METHODS: Appropriate for gestational age newborns < 1500 g birth weight were enrolled prospectively. Response to ACTH stimulation was tested on days 5, 6, or 7. Baseline cortisol, stimulated cortisol, and magnitude of response were compared between babies who developed bronchopulmonary dysplasia (BPD), defined as oxygen dependence at 28 days, and those who recovered without BPD. RESULTS: In this population, the cortisol response to ATCH increased with increasing birth weight (P < .001). Using birth weight as a cofactor, analysis of variance showed that patients who developed BPD (n = 34, BW 974 +/- 192 g, mean +/- S.D.) had significantly reduced responses to ACTH at 5 to 7 days of age compared to those who recovered (n = 25, BW 1251 +/- 194 g), P = .006. Additionally, 84% of patients who recovered without BPD, but only 26% of BPD patients, achieved a prospectively defined positive cortisol response to ACTH (> or = 9 micrograms/dL; P < .005). Supplemental oxygen was discontinued at a younger postconceptional age in babies with a positive cortisol response to ACTH (P < .01) and fewer of those babies were on supplemental oxygen at 36-week postconceptional age (P < .01). CONCLUSIONS: At the end of the first week of life, infants who subsequently developed BPD and prolonged oxygen dependence had significantly lower cortisol secretion in response to ACTH than infants who recovered without BPD. We speculate that these babies may be unable to secrete adequate amounts of cortisol in a setting of increased stress, leaving them vulnerable to continuing lung injury.

Adrenocorticotropic Hormone↗
PubMed1994

Identification of unstable angina patients who have favorable outcome with medical or surgical therapy (eight-year follow-up of the Veterans Administration Cooperative Study).

To identify patients with unstable angina (UA) who have favorable outcomes with medical therapy or surgery, 468 patients who had been randomized in the Veterans Administration Cooperative Study of UA were risk-stratified based on angiographic criteria of the number of coronary arteries diseased and left ventricular ejection fraction (LVEF). Patients at high risk for UA were defined as those with 3-vessel disease or LVEF of < or = 58%, and patients at low risk were those with 1- or 2-vessel disease and LVEF of > 58%. Of the 468 UA patients randomized, 287 patients belonged to the high-risk and 181 to the low-risk category. In the low-risk group, cumulative mortality after 8 years of follow-up was significantly lower in the medically treated patients (16.8%) than in the surgically treated patients (32.2%) (p = 0.022); in the high-risk group, cumulative mortality was significantly lower in the surgically treated patients (24.1%) than in the medically treated patients (35.3%) (p = 0.03). The relative risk of surgery (the ratio of surgical to medical risk) in the low-risk patients was 1.67, indicating a significant survival advantage with medical treatment (p = 0.05), whereas the relative risk of surgery for the high-risk group was 0.71, indicating a significant survival benefit with surgical treatment (p < 0.05). Thus, medical therapy appears to be the preferred therapy for UA patients with only 1- or 2-vessel disease and normal LVEF, and surgery is preferred for UA patients with 3-vessel disease or LVEF in the lowest tercile.

Angina, Unstable↗
PubMed1994

Serious group A beta-hemolytic streptococcal infections complicating varicella.

STUDY OBJECTIVE: To alert practicing emergency physicians to an important and possibly increasing relationship between life-threatening group A beta-hemolytic streptococcal (GABHS) infections and children recovering from varicella. DESIGN: A case series of six patients managed from January through March 1993. SETTING: A university-affiliated pediatric specialty emergency department. TYPE OF PARTICIPANTS: Six previously healthy immunocompetent children between 1 and 5 years of age seen in our ED over a nine-week period. RESULTS: Six children had onset of varicella two days to two weeks before developing a serious life-threatening GABHS infection. Children presented with clinical symptoms of invasive GABHS infection with bacteremia (one patient); streptococcal toxic shock syndrome with negative blood culture (two), pneumonia with pleural effusion and streptococcal toxic shock syndrome (one), pneumonia with pleural effusion (one), and pyomyositis of the thigh (one). Four of six patients required intensive care admissions and aggressive support of vital signs. All six survived. CONCLUSION: Emergency physicians should be aware of the association between varicella and serious GABHS infections and be prepared to recognize and aggressively manage serious complications should they occur.

Cellulitis↗
PubMed1994

The role of circulating cells in the healing of vascular prostheses.

PURPOSE: Cells covering the flow surface of vascular prostheses are derived in part from endothelium of adjacent native artery and from capillaries that extend through the pores of the graft. This study is designed to determine whether these endothelial-like cells can also originate from circulating blood cells and if so to identify them with protein markers. METHODS: Pledgets of vascular graft material were suspended within the aortas of dogs with metal stents that isolated the pledgets from the aortic wall. Explanted pledgets were examined for cells containing factor VIII-related antigen and other markers identified with monoclonal antibodies. RESULTS: A monolayer of cells that stained positive for factor VIII formed on pledgets after 7 days. Pledgets removed after 55 days had endothelial cells, smooth muscle cells, macrophages, monocytes, and capillary-like structures which were identified by staining for the monoclonal antibodies 43 beta E3 (vimentin), HHF35 (alpha and gamma muscle actin), CGA7 (smooth muscle actin), and HAM56 (macrophage). Woven and knitted polyester and extruded polytetrafluoroethylene pledgets healed in a similar manner. CONCLUSION: The origin of the cells identified is speculative but they appear to have been derived from circulating cells, possibly stem cells, which are capable of differentiation because the pledgets on which the cells were identified were isolated from aortic wall endothelium and perivascular capillaries.

Animals↗
PubMed1994

VA Study of Unstable Angina. 10-year results show duration of surgical advantage for patients with impaired ejection fraction.

BACKGROUND: In a randomized study of unstable angina, medically treated patients with impaired left ventricular (LV) ejection fractions (EF = 0.3 to 0.58) were at significantly higher risk of mortality than patients treated by coronary artery bypass graft surgery (CABG). Because the duration of this surgical advantage is unknown, 10-year cumulative mortality rates of patients with impaired LVEF were determined and compared with the previously observed rates at 2, 5, and 8 years. METHODS AND RESULTS: Of 468 patients with unstable angina, 237 were randomized to receive medical treatment alone and 231 patients to have CABG. Baseline characteristics, which were equally distributed between the two treatment groups, included age, LVEF, number of diseased coronary arteries, diabetes, clinical presentation (type I or type II), prior myocardial infarction, and smoking. Mortality was determined by life-table analysis and risk factors by logistic regression analysis. Patients were divided into terciles according to LVEF, and the mortality rates of medical and surgical patients in the lowest tercile were compared. The 10-year mortality rate for all medical patients was 38% and for all surgical patients, 39%. When LVEF was treated as a continuous variable, there was a significant relation between mortality and LVEF for medically treated patients but not for surgical patients. The cumulative mortality rate for the lowest-tercile (EF 0.3 to 0.58) medical patients was 49%; for the lowest-tercile surgical patients, 41% (P = .15). CONCLUSIONS: The surgical advantage for patients with impaired LVEF that was significant at 5 years (P = .03) and 8 years (P = .05) appears to have diminished at 10 years (P = .15).

Angina, Unstable↗
PubMed1991

Effects of subchronic amphetamine or amfonelic acid on rat brain dopaminergic and serotonergic function.

Repeated doses of direct or indirect CNS stimulants are known to cause behavioral hypersensitivity. The biochemical basis for hypersensitization remains unclear. Since the dopaminergic system uses a large storage pool that is only slowly mobilized to releasable sites, a change in this relationship may underlie the biochemical changes leading to increased responsiveness to stimulants. To test this hypothesis, rats were first tested with low doses of 2.5 mg/kg amphetamine or 1.0 mg/kg amfonelic acid (AFA) for their locomotor response, then 5.0 mg/kg amphetamine or 2.5 mg/kg AFA were injected daily for 7 days and the rats retested with the lower doses of amphetamine or AFA, respectively. Both drugs produced hypersensitivity, but the cataleptic response to acute dopamine (DA) receptor blockade by haloperidol was unaltered. The ability of haloperidol to increase DA metabolism was unaltered and the ability of acute AFA to synergize with haloperidol was similar in the striatum of stimulant and saline treated rats, but reduced in the medial prefrontal cortex of both AFA and d-amphetamine treated rats. Additional rats had DA2 receptor sensitivity measured in the striatum and frontal cortex, but no significant differences were found. Only amphetamine caused a significant decrease in frontal cortex serotonin type 2 receptors. Since there was no alteration in the ability of AFA to increase neurogenic release of DA in the striatum and a decrease occurred in prefrontal cortex, an increase in the storage to functional pool exchange in the nigrostriatal and mesocortical DA containing neurons seems unlikely. In contrast, both the amphetamine and AFA treatment groups had their brain 5HT and 5HIAA levels reduced by about 50%. This suggests that changes in other transmitter systems may have a permissive effect allowing exaggerated responses to excessive DA release.

Amphetamine↗
PubMed1991

Intraoperative management of severe endobronchial hemorrhage.

Endobronchial hemorrhage due to pulmonary artery perforation by a Swan-Ganz catheter developed during coronary artery bypass grafting while weaning from cardiopulmonary bypass. After reinstitution of cardio-pulmonary bypass with pulmonary artery venting, bleeding was localized to the right lower lobe bronchus using fiberoptic bronchoscopy. A Fogarty embolectomy catheter was inflated in the bronchus to tamponade successfully only the right lower lobe. This case illustrates a method of distal bronchial blockade for maximal retention of pulmonary function and avoidance of pulmonary resection.

Blood Loss, Surgical↗
PubMed1991

Quality of life after bypass surgery for unstable angina. 5-year follow-up results of a Veterans Affairs Cooperative Study.

To assess the effect of bypass surgery on outcome from unstable angina, 468 patients were randomized to medical treatment (237 patients) or surgery plus medical treatment (231 patients) and have been followed for comparison of survival, cardiac end points, and quality of life; the latter end point is discussed in the present report. Data were available at 3 and 5 years for 80% and 82% of patients in the medical group, respectively, and 77% and 80% of patients in the surgery group, respectively. At 3 months after randomization to therapy, 79.8% of patients in the surgery group reported subjective improvement, compared with 58% of the medical group, 12.6% of the surgery group reported no change compared with 24.5% of the medical group, and 5.5% of the surgery group reported worsening compared with 24.5% of the medical group (p less than 0.01 by chi 2). Similar data were found for chest pain status, and the benefit to the surgery group remained statistically significant through 5 years of follow-up. Crossover rate to surgery was 43% by 5 years. Treadmill duration was increased in the surgery group compared with the medical group (6.5 +/- 0.25 versus 5.3 +/- 0.25 minutes at 6 months, p less than 0.01), and a significant difference was again demonstrated at 3 and 5 years. A trend toward decreased recurrence of unstable angina was present in the surgery group at 1 year (six of 168 [3.6%] versus 13 of 187 [6.9%] in the medical group, p = 0.158), but the two groups were similar at 3 and 5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina, Unstable↗
PubMed1991

Developmental pattern of urinary epidermal growth factor in the premature infant and the influence of gender.

We report the cross-sectional pattern of first day urinary epidermal growth factor/creatinine (EGF/Cr) levels in 159 appropriate for gestational age infants born at 26-41 weeks gestation. EGF/Cr levels rose significantly earlier in female infants than levels in male infants. In female infants levels were similar to term levels beginning at 30-32 weeks. Mean EGF/Cr levels in male infants were similar to term values beginning at 32-34 weeks. We could not demonstrate any influence from acute perinatal events on EGF/Cr levels. In a subset of 28 infants, a weekly longitudinal study of urinary EGF/Cr levels was undertaken. The urinary EGF/Cr pattern correlated significantly with both corrected gestational and postnatal ages. A significant change in the EGF/Cr pattern was observed at a corrected gestational age of 32 weeks and at 4 weeks postnatal age. There was no significant difference in EGF/Cr levels between males and females. Our results demonstrated a significant difference in first day urinary EGF/Cr levels between female and male preterm infants during the early third trimester. This difference was seen at a time in gestation when other gender-specific maturational and growth differences are noted. When infants born at less than 32 weeks gestational age were followed longitudinally, the urinary EGF/Cr pattern, when expressed by corrected gestational age, was significantly modified from that in the cross-sectional study.

Creatinine↗