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Biomedical subjects

D Russell

Publications and source records attributed to D Russell.

At least 127 records · Page 7Linked to original sources
PubMed1995

Manual compared with target-controlled infusion of propofol.

We studied 160 ASA I-II patients, anaesthetized with propofol by infusion, using either a manually controlled or target-controlled infusion system. Patients were anaesthetized by eight consultant anaesthetists who had little or no previous experience of the use of propofol by infusion. In addition to propofol, patients received temazepam premedication, a single dose of fentanyl and 67% nitrous oxide in oxygen. Each consultant anaesthetized 10 patients in sequential fashion with each system. Use of the target-controlled infusion resulted in more rapid induction of anaesthesia and allowed earlier insertion of a laryngeal mask airway. There was a tendency towards less movement in response to the initial surgical stimulus and significantly less movement during the remainder of surgery. Significantly more propofol was administered during both induction and maintenance of anaesthesia with the target-controlled system. This was associated with significantly increased end-tidal carbon dioxide measurements during the middle period of maintenance only, but recovery from anaesthesia was not significantly prolonged in the target-controlled group. With the exception of a clinically insignificant difference in heart rate, haemodynamic variables were similar in the two groups. Six of the eight anaesthetists found the target-controlled system easier to use, and seven would use the target-controlled system in preference to a manually controlled infusion. Anaesthetists without prior experience of propofol infusion anaesthesia quickly became familiar with both manual and target-controlled techniques, and expressed a clear preference for the target-controlled system.

Adolescent↗
PubMed1995

Cerebral vasoreactivity assessed with transcranial Doppler and regional cerebral blood flow measurements. Dose, serum concentration, and time course of the response to acetazolamide.

BACKGROUND AND PURPOSE: To improve the assessment of cerebral vasoreactivity using acetazolamide (ACZ), we studied the time course of the response and the relationship between dose, response, and serum concentration. METHODS: Blood flow velocities were measured with the use of transcranial Doppler ultrasonography in one of the middle cerebral arteries of 48 healthy subjects after the intravenous administration of 1 to 1.6 g ACZ. In 34 subjects (group 1), velocities were measured every second minute to detect the maximum middle cerebral artery velocity increase. We also measured regional cerebral blood flow using single-photon emission computed tomography in 27 of the subjects in group 1 before and approximately 15 to 20 minutes after the ACZ injection. The serum concentration of ACZ was measured in 15 subjects. In the remaining 14 subjects (group 2), middle cerebral artery velocity measurements were made 10, 25, 30, and 45 minutes after ACZ administration to obtain information regarding the late time course of the response. RESULTS: In group 1 the plateau phase of the velocity response was reached 8 to 15 minutes after ACZ administration. A large range of velocity increase was observed, and a significant correlation was found between the maximum velocity increase and the dose and serum concentration of ACZ. In group 2 subjects, maximum velocities were maintained 30 minutes after the injection, but after 45 minutes velocities had decreased to 68% of their highest level. No significant relationship was found between dose or serum concentration of ACZ and the regional cerebral blood flow increase. The velocity increase after ACZ was similar in both older and younger subjects. CONCLUSIONS: This study shows that cerebral vasoreactivity is best assessed 10 to 30 minutes after ACZ administration and that the dose should probably exceed 15 mg/kg if a maximum vasodilatory response in the cerebral circulation is to be obtained.

Acetazolamide↗
PubMed1995

Incidence and frequency of cerebral embolic signals in patients with a similar bileaflet mechanical heart valve.

BACKGROUND AND PURPOSE: The aim of this study was to determine the incidence and frequency of cerebral embolic signals in a patient population with the same mechanical heart valve using transcranial Doppler examination. Furthermore, it aimed to identify patient and valve characteristics that correlated with the occurrence of these signals. METHODS: Ninety-two patients with Carbomedics valves and 15 healthy control subjects took part in the study. Thirty-six patients were examined before and immediately after valve implantation (group 1), 34 patients 1 year after surgery (group 2), and 22 patients 5 years after surgery (group 3). Cerebral embolic signals were detected using transcranial Doppler monitoring of the right middle cerebral artery. RESULTS: Asymptomatic cerebral embolic signals were detected in 87% of the total 92 patients, in 77.8% of group 1 patients, in 91.2% of group 2 patients, and in 95.5% of group 3 patients. No cerebral embolic signals were detected in group 1 patients before surgery or in control subjects. The incidence (P = .04) and frequency (P = .002) of cerebral embolic signals increased significantly with longer duration of valve implantation. A significant positive correlation was also found between frequency of cerebral embolic signals and valve size (r = .4326, P = .00001). Median frequency of embolic signals in patients with a history suggestive of cerebrovascular events (n = 14) was 60 signals per hour compared with 11 signals per hour in those with no such history (n = 42; P = .04). CONCLUSIONS: The incidence and frequency of cerebral embolic signals increased with the duration of valve implantation. The frequency of these signals also was dependent on valve size. Patients who had experienced cerebrovascular symptoms had a higher frequency of cerebral embolic signals compared with those with no such signals. These results should be interpreted with caution but suggest that this method could be of help in assessing the risk of stroke in prosthetic heart valve patients and that prospective clinical studies should now be carried out.

Adult↗
PubMed1995

Postinfarct cardiac free wall rupture: the relationship of rupture site to papillary muscle insertion.

The objective of this study was to examine for any relationship between the sites of papillary muscle insertion in left ventricular free wall (LVFW) and the site of LVFW rupture postinfarct. Twenty-five consecutive patients with LVFW rupture (12 men and 13 women, mean age 72.3 yr, range = 48 to 93) at the University of Ottawa Heart Institute during the period of July 1, 1988 to 1992 were studied. Clinical charts were reviewed, and the Formalin-fixed hearts were re-examined grossly and microscopically. Each patient died of tamponade or after surgery for tamponade. Eight (32%) of the 25 infarcts were anteroseptal or anterior, 11 of 25 (44%) were lateral, and 6 of 25 (24%) were inferior or inferoseptal. Four (16%) of the 25 infarcts were less than 2 days old, 9 of 25 (36%) were 2 to 5 days old, and 12 of 25 (48%) were 5 to 10 days old. A separate pre-existent and healed infarct was noted in 36% of patients; however, rupture adjacent to these areas of old infarct occurred in only 8% of cases. In 15 of 25 (60%) cases, free wall rupture occurred in the lateral wall between and at the level of the two papillary muscles. In a further 5 of 25 (20%) cases, the rupture was beside one of the papillary muscles but in anterior or posterior walls. In 20 of 25 (80%) cases, the endocardial tear associated with the LVFW rupture was within 1 cm of the base of one of the papillary muscles as they inserted in LVFW.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Immune responses in patients with T-cell lymphoma treated with an anti-idiotype antibody mimicking a highly restricted T-cell antigen.

We generated an IgG1 murine monoclonal anti-idiotype antibody (Ab2) to a highly restricted T-cell antigen designated glycoprotein (gp) 37 that is found on T-cell malignancies but not on normal cells. gp37 is identified by the murine monoclonal antibody SN2 (Ab1) against which the Ab2 was raised. Each of four patients with T-cell lymphoma predominantly confined to the skin received a minimum of four intracutaneous injections of aluminum hydroxide precipitated anti-idiotype murine monoclonal antibody (1 mg/injection) given every 2 weeks. For responding patients, injections were continued on a monthly basis. All tumors were measured along orthogonal major and minor axes, using a ruler and/or calipers, by the same observer. Tumor sizes were documented photographically. Three of the four patients developed specific idiotypic humoral immune responses, and two of the four patients also demonstrated idiotypic cell-mediated responses. Humoral responses included binding of the patients' sera to the anti-idiotype antibody as well as specific inhibition of binding of the SN2 antibody (Ab1) to the anti-idiotype antibody (Ab2). Anti-anti-idiotypic (Ab3) antibody from one patient's serum bound specifically to the gp37-positive cell line MOLT-4 and also to semipurified gp37 antigen. Cell-mediated responses were demonstrated by specific proliferative response to the aluminum hydroxide precipitated anti-idiotype antibody by patients' peripheral blood mononuclear cells. While three of the four patients had extensive disease and did not have clinical responses, one of the patients who had nine discrete skin tumors and peripheral blood involvement without other detectable disease had virtually complete disappearance of the tumors lasting over 11 months. Our results demonstrate that this particular anti-idiotype antibody can induce humoral and cellular immune responses, and at least in one patient led to a meaningful therapeutic response. Future trials should focus on immunocompetent patients with minimal disease.

Amino Acid Sequence↗
PubMed1994

Grommets, tonsillectomies, and deprivation in Scotland.

OBJECTIVE: To see whether there is a relation between grommet insertion operation and tonsillectomy rates, otolaryngology services, and deprivation scores in Scotland. DESIGN: Analysis of routine 1990 NHS data on grommet insertions and tonsillectomies in Scottish children aged 0-15 years compared with data on general practitioner and otolaryngology services and Carstairs deprivation scores. SETTING: All 15 Scottish health boards. SUBJECTS: All children aged 0-15 (1,021,933). RESULTS: Tonsillectomy was more common than grommet insertion operations in Scotland (6182:4850). Health boards with high grommet insertion rates were more likely to have low tonsillectomy rates (Spearman's rank correlation -0.59; 95% confidence interval -0.87 to -0.03). Grommet insertion rates varied fourfold (from 2.4/1000 to 9.2/1000) and tonsillectomy rates twofold (from 3.6/1000 to 8.0/1000) across Scottish health boards. Variation between health boards had changed over the 15 years 1975-90. Variation in grommet insertion rates did not reflect variation in the supply of otolaryngology consultants (Spearman's rank correlation -0.25). There was a non-significant tendency for high general practitioner referral rates to be associated with high grommet insertion rates, low tonsillectomy rates, and less deprived areas (Spearman's rank correlation coefficients 0.50, -0.53, and -0.43). Deprivation (measured by Carstairs scoring for each health board) was associated with higher tonsillectomy rates (Spearman's rank correlation 0.41; 95% confidence interval -0.22 to 0.80) and significantly lower grommet insertion rates (-0.73; -0.92 to -0.28). CONCLUSION: Social factors as well as differences in disease prevalence and medical practice need to be considered when studying variation in childhood grommet insertion and tonsillectomy rates.

Adolescent↗
PubMed1994

Simultaneous assessment of vasoreactivity using transcranial Doppler ultrasound and cerebral blood flow in healthy subjects.

Blood flow velocities in both middle cerebral arteries and regional cerebral blood flow in their perfusion territories were measured simultaneously in 36 healthy subjects. In 20 subjects, the measurements were first performed under basal conditions and then repeated 15-20 min after an intravenous injection of 1 g of acetazolamide. Reproducibility of simultaneous blood flow and velocity measurements was tested by examining 16 subjects on two occasions under basal conditions with an interval of 20 min. Relatively good reproducibility was found for repeated measurements of velocity and blood flow, being best when side-to-side asymmetry was assessed. The increase in blood flow velocities after acetazolamide was symmetrical (right side, 34.2%; and left side, 35.5%), and the velocity increase was significantly correlated with basal values. The increase in cerebral blood flow was also symmetrical (right side, 29.8%; left side, 30.1%) but not correlated with basal flow values. No significant relationship was found between velocity increase and increase in regional cerebral blood flow. This finding is probably not only due to methodological inaccuracies but may suggest that acetazolamide has an effect on the diameter of the middle cerebral artery or on the magnitude of this artery's perfusion territory. This study supports the use of acetazolamide for assessing cerebral vasoreactivity following the definition of lower limits for velocity and flow increase and for asymmetry of the response.

Acetazolamide↗
PubMed1994

Cerebral vasoreactivity in unilateral carotid artery disease. A comparison of blood flow velocity and regional cerebral blood flow measurements.

BACKGROUND AND PURPOSE: Hemodynamic information obtained by assessing cerebral vasoreactivity is of clinical interest and may have prognostic significance in patients with occlusive carotid disease. The aim of this study was to compare the results of transcranial Doppler and regional cerebral blood flow studies when used to assess cerebral vasoreactivity. METHODS: Blood flow velocities in both middle cerebral arteries and regional cerebral blood flow in their respective perfusion territories were compared in 52 patients with severe unilateral carotid stenosis or occlusion. The studies were first performed under basal conditions and repeated after the intravenous administration of 1 g acetazolamide. RESULTS: Asymmetry (normal compared with pathological side) in middle cerebral artery blood velocity increase was significantly greater than the asymmetry in cerebral blood flow increase in the perfusion territories of the arteries. A significant correlation (r = .63, P < .0001) was found between asymmetry in percent velocity increase and asymmetry in absolute cerebral blood flow increase. The two methods agreed in their assessment of either a normal or a reduced vasoreactivity in 38 subjects and disagreed in 14. In six of the latter patients, who had no evidence of cerebral infarction, the asymmetry in velocity increase was abnormal, whereas asymmetry in flow increase was assessed as normal. CONCLUSIONS: We found a good correlation between the asymmetry in regional cerebral blood flow increase in the middle cerebral artery perfusion territories and asymmetry in the velocity increase in the middle cerebral arteries after administration of acetazolamide. These results suggest that transcranial Doppler examination combined with the acetazolamide test may be used in clinical situations to assess cerebral vasoreactivity.

Adult↗
PubMed1994

Recombinant human insulin-like growth factor (IGF)-binding protein-1 inhibits somatic growth stimulated by IGF-I and growth hormone in hypophysectomized rats.

We have examined the effects of exogenously administered recombinant human insulin-like growth factor-binding protein-1 (rhIGFBP-1) alone and in combination with recombinant human insulin-like growth factor-I (rhIGF-I) or human GH on weight gain and tibial epiphysis enlargement in hypophysectomized rats. rhIGF-I, given twice daily by sc injection, increased both growth parameters in a dose-dependent manner. Coadministration of increasing amounts of rhIGFBP-1 with a constant amount of rhIGF-I (80 micrograms/injection, given twice daily) resulted in a dose-dependent inhibition of the growth-promoting effects of rhIGF-I. A rhIGFBP-1 dose of 9.8 micrograms/injection (an IGFBP-1/IGF-I molar ratio of 0.04:1) caused no significant effect on rhIGF-I-stimulated growth parameters, whereas a rhIGFBP-1 dose of 1200 micrograms/injection (IGFBP-1/IGF-I molar ratio of 5:1) resulted in 78% or greater inhibition of rhIGF-I-stimulated growth (P < 0.05). rhIGFBP-1 doses of 48 and 240 micrograms/injection (IGFBP-1/IGF-I molar ratios of 0.2:1 and 1:1, respectively) had intermediate inhibitory effects. None of the rhIGFBP-1 doses potentiated the growth-promoting effects of rhIGF-I. Rats treated with rhIGFBP-1 alone (twice daily injections of 9.8, 48, 240, or 1200 micrograms) showed no significant differences in growth parameters compared to rats treated with vehicle. Coadministration of rhIGFBP-1 (1200 micrograms/injection, given twice daily) with GH (15 mU/injection, given twice daily) inhibited weight gain and tibial epiphysis enlargement stimulated by GH by at least 50% in each of two experiments (P < 0.05). These studies demonstrate that nonphosphorylated rhIGFBP-1 can inhibit the growth-promoting effects of rhIGF-I and GH in vivo. The results suggest that in addition to its proposed role in glucose homeostasis, IGFBP-1 may play a role in inhibiting somatic growth and other physiological functions stimulated by IGF-I and GH.

Animals↗
PubMed1994

Incidence of renal failure in NIDDM. The Oklahoma Indian Diabetes Study.

The incidence of and risk factors for renal failure were determined in 912 Oklahoma Indians with non-insulin-dependent diabetes mellitus in a follow-up study conducted between 1987 and 1990. The incidence rate was 15.7/1,000 person-years after an average follow-up time of 10.2 years. Among those who had no qualitatively positive proteinuria at baseline, the incidence of renal failure was 10.3/1,000 person-years compared with 19.3- and 56.2/1,000 person-years, respectively, in those with slight and heavy proteinuria at baseline. Fasting plasma glucose (FPG) > or = 11.1 mM (200 mg/dl) increased the risk of renal failure to 2.9-fold (95% confidence interval [CI] = 1.9-4.6) higher than a level < 7.8 mM (140 mg/dl), and twofold (95% CI = 1.4-3.1) higher than a level between 7.8 (140 mg/dl) and 11.1 mM (200 mg/dl). The hypertensive patient had twice the incidence of renal failure than the normotensive subject (rate ratio = 2.1, 95% CI = 1.4-3.0). Patients with a lower blood pressure under antihypertensive medication had a lower incidence of renal failure than those whose hypertension remained uncontrolled with or without use of medication. Significant independent risk factors for renal failure, identified from Cox's proportional hazards model, were duration of diabetes, FPG, age, hypertension, and insulin use (P < 0.05). In patients without proteinuria at baseline, FPG and hypertension were significant predictors of renal failure as identified by multivariate analyses, whereas in patients who had proteinuria at baseline, insulin use was significant. Thus, hyperglycemic and hypertension control are suggested strongly for diabetic Oklahoma Indians as potential strategies to prevent the development of renal failure.

Adult↗
PubMed1994

Maternal attitudes as predictors of infant feeding decisions.

To achieve the goal of Healthy People 2000 of increasing the rate and duration of breast-feeding in the United States, it is important to determine how maternal attitudes influence choice of infant feeding method. This study of postpartum women explores the extent to which maternal attitudes concerning process (how the baby is fed) and product (what the baby is fed) can predict the method of infant feeding during the hospital stay. A cross-sectional analysis of mothers' attitudes and infant feeding behavior was conducted. The participants included 216 mothers of infants less than 48 hours of age. Sociodemographic characteristics and maternal attitudes were analyzed to determine their ability to predict choice of feeding method. The results of the study indicate that maternal attitudes are better predictors of feeding method than are sociodemographic factors. These attitudinal variables, reflecting concerns over food intake, infant nutrition, and parental role, were most strongly related to choice of infant feeding method. The study indicates that maternal attitudes concerning the process and product dimensions of infant feeding provide valuable information regarding the women most likely to select either breast-feeding or formula-feeding. To increase the rate of breast-feeding, interventions should be developed that are consonant with positive maternal attitudes concerning the process and product dimensions of breast-feeding.

Adolescent↗
PubMed1994

A rare cause of intra-operative hypoxaemia.

A 25-year-old man underwent left inguinal hernia repair. Following induction of anaesthesia, desaturation below 90% was noted which persisted despite correct placement of an endotracheal tube and ventilation with 100% oxygen. Surgery was allowed to continue, and the suspected diagnosis of pulmonary arterio-venous malformation was confirmed post-operatively by computerized axial tomography and arteriography. The investigation and treatment are described, and the diagnostic value of pulse oximetry in this case is emphasized.

Adult↗