Biomedical subjects

S Lowe

Publications and source records attributed to S Lowe.

At least 55 records · Page 3Linked to original sources

PubMed1993

Thoracic epidural anaesthesia in infants and children.

When compared with conventional analgesic techniques, epidural anaesthesia not only provides improved analgesia, but also has several beneficial effects on the postoperative respiratory, cardiovascular, and metabolic status of the patient. Although the efficacy and safety of caudal and lumbar epidural anaesthesia in children has been demonstrated, there is little information concerning the use of thoracic epidural anaesthesia. The purpose of our review was to evaluate the safety of thoracic epidural anaesthesia in infants and children. We retrospectively reviewed our three-year experience with thoracic epidural anaesthesia for postoperative analgesia in children. Epidural catheters were placed at the thoracic level without difficulty in 63 children ranging in age from three months to 18 yr and in weight from 3.2 to 78 kg. Postoperative analgesia was provided by the continuous infusion of a bupivacaine/fentanyl mixture, supplemented with intermittent epidural fentanyl by bolus as needed. Epidural catheters were successfully placed in all patients. No inadvertent dural punctures were noted. No episodes of respiratory depression related to epidural analgesia occurred. Minor adverse effects including pruritus occurred in six patients, three of whom required pharmacological intervention with diphenhydramine. Our review suggests that this is a safe and effective method of postoperative analgesia following thoracic surgery in children.

Adolescent↗

PubMed1993

Continuous regional anaesthesia in infants.

Physiological immaturity of the respiratory musculature and central respiratory control centres leads to an increased risk of apnoea and respiratory complications following general anaesthesia in neonates. Regional anaesthetic techniques may obviate the need for general anaesthesia and lessen the risks of perioperative morbidity. Although these techniques have been described in infants, previous reports have dealt with single-shot techniques for brief surgical procedures (< 60 min). Experience with prolonged operative cases using regional anaesthesia via indwelling catheters in infants is limited. We present our experience with four infants in whom either caudal epidural or spinal anaesthesia was administered via indwelling catheters for operative procedures that lasted 90 to 180 min. We believe this technique is an alternative to general anaesthesia in these patients.

Anesthesia, Caudal↗

PubMed1993

The effect of captopril on the superior mesenteric artery and portal venous blood flow in normal man.

1. Measurements of superior mesenteric artery and portal venous blood flow were made non-invasively along with systemic and other regional (cardiac index, forearm and cutaneous blood flow) vascular responses to acute ingestion of the ACE inhibitor captopril (50 mg) or placebo (50 mg vitamin C), in 12 healthy subjects while supine and during head-up tilt. 2. After captopril, superior mesenteric artery and portal blood flow rose markedly with a reduction in superior mesenteric artery vascular resistance. Supine blood pressure was unchanged but cardiac index and forearm blood flow rose; during head-up tilt, blood pressure fell in some subjects. 3. There was a rise in levels of plasma renin activity and a fall in levels of plasma angiotensin II after captopril. After placebo, there were no significant changes in splanchnic blood flow, systemic or other regional responses and in biochemical measurements, while supine. 4. Our studies indicate that captopril is a potent dilator of the splanchnic vascular bed and suggest that this action may contribute to its therapeutic effects. The studies indicate a role for angiotensin II in the control of this large vascular bed although other agents (bradykinin, prostacyclin) may contribute.

Adult↗

PubMed1993

Effects of dietary fats from animal and plant sources on diet-induced fatty streak lesions in C57BL/6J mice.

This study was designed to determine the effects of a variety of naturally occurring saturated fats on aortic lesion formation in C57BL/6J mice that are susceptible to diet-induced fatty streak lesions. Groups of female mice were randomly assigned to one of seven treatment groups and were fed diets containing 15% (w/w) hydrogenated coconut oil, hydrogenated soy oil, hydrogenated palm oil, cocoa butter, lard, tallow, or dairy butter, 1% cholesterol, and 0.5% cholic acid. Plasma lipid levels were measured to determine whether lesion formation was related to specific changes in these parameters. Lesions, which were observed in all groups of mice, ranged from 420 to 3220 microns2/aortic cross section. Lesion area was positively correlated to the percentage of saturated fatty acids contained in the fat sources and the ratio of combined VLDL plus LDL-cholesterol to HDL-cholesterol and inversely correlated to monounsaturated fatty acids content and to HDL-cholesterol levels. Results from this study demonstrate that inbred mice may provide a good model for dissecting the genetic basis for the differential atherogenic responses to diet-induction and for studying the effects of dietary factors on aortic lesion development.

Animals↗

PubMed1992

Assessment of breast cancer size: a comparison of methods.

Two hundred women presenting with primary breast carcinoma were studied to find the most accurate single or combination of methods to assess breast tumour size. Correlations of the maximum clinical, mammographic and ultrasound tumour diameter were made with maximum histological diameter. Tumour size could be assessed clinically in all 200 patients, and overestimated the size of small tumours and underestimated large tumours (P less than 0.001). Mammographic measurement, which was possible in 145 (72.5%), underestimated the size of large tumours (P less than 0.01). Only 100 women underwent ultrasound examination (size assessed in 86%) and this modality tended to underestimate the size of all tumours (P less than 0.05). All methods of measurement showed similar correlations with histological size. Stepwise linear regression showed that the most accurate and practical estimation could be made using the formula: Histological size = 0.5 x mammographic size + 0.5 x clinical size. We conclude that clinical measurement of breast cancer size is as accurate as that from mammography or ultrasound. Accuracy can be improved by the use of a simple formula of both clinical and mammographic measurements.

Breast Neoplasms↗

PubMed1991

Characterization of hypersensitive sites, protein-binding motifs, and regulatory elements in both promoters of the mouse porphobilinogen deaminase gene.

Porphobilinogen deaminase, the third enzyme in the heme biosynthetic pathway, is encoded by a gene having two different promoters. Differential splicing of transcripts from the promoters yields two distinct mRNA species that are translated to give two isoforms of the protein. One isoform is ubiquitous, whereas the other is erythroid-specific. In this study, we have analyzed the gene regulatory elements that contribute to the tissue-specific promoter utilization of the mouse porphobilinogen deaminase gene. Six nuclear DNase I-hypersensitive sites were mapped in erythroid and nonerythroid cells, and four of these regions were further analyzed for in vitro nuclear protein-binding sites. The erythroid-specific promoter contains three erythroid nuclear factor GF-1-binding sites. The proximal GF-1-binding site, together with an adjacent duplicated CACCC motif, was sufficient to confer erythroid-specific expression in functional studies. Furthermore, as upstream gene sequences were shown to greatly increase promoter activity in erythroid cells, it suggests an upstream erythroid-specific enhancer may also be required for the up-regulation of the erythroid-specific promoter during erythropoiesis.

Animals↗

PubMed1991

Enhancer dependent expression of the chicken beta-hatching globin gene during erythroid differentiation.

The activity of the chicken beta H globin gene promoter has been analysed in functional assays in both chicken and murine erythroleukaemia cells. Sequences between -251 and -146 bp, in the presence or absence of the chicken beta globin locus enhancer, strongly repress transcription in erythroid cells before and after the induction of terminal differentiation. A 50 bp sequence (-98 to -146 bp), which contains adjacent cGATA-1 and NF1 protein binding sites in vitro, and which is bound by non-histone protein in vivo, is essential for full promoter activity. Mutagenesis studies indicate that both protein binding sites are required. During terminal differentiation, both the absence of repressor and the presence of the erythroid enhancer are required for maximal promoter activity, suggesting that the beta A, beta epsilon and beta H globin gene promoters compete for the enhancer during development.

Animals↗

PubMed1991

Influence of CO(2)-HCO(3) Levels and pH on Growth, Succinate Production, and Enzyme Activities of Anaerobiospirillum succiniciproducens.

Growth and succinate versus lactate production from glucose by Anaerobiospirillum succiniciproducens was regulated by the level of available carbon dioxide and culture pH. At pH 7.2, the generation time was almost doubled and extensive amounts of lactate were formed in comparison with growth at pH 6.2. The succinate yield and the yield of ATP per mole of glucose were significantly enhanced under excess-CO(2)-HCO(3) growth conditions and suggest that there exists a threshold level of CO(2) for enhanced succinate production in A. succiniciproducens. Glucose was metabolized via the Embden-Meyerhof-Parnas route, and phosphoenolpyruvate carboxykinase levels increased while lactate dehydrogenase and alcohol dehydrogenase levels decreased under excess-CO(2)-HCO(3) growth conditions. Kinetic analysis of succinate and lactate formation in continuous culture indicated that the growth rate-linked production rate coefficient (K) cells was much higher for succinate (7.2 versus 1.0 g/g of cells per h) while the non-growth-rate-related formation rate coefficient (K') was higher for lactate (1.1 versus 0.3 g/g of cells per h). The data indicate that A. succiniciproducens, unlike other succinate-producing anaerobes which also form propionate, can grow rapidly and form high final yields of succinate at pH 6.2 and with excess CO(2)-HCO(3) as a consequence of regulating electron sink metabolism.

Journal Article↗

PubMed1990