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Biomedical subjects

M C Lewis

Publications and source records attributed to M C Lewis.

18 recordsLinked to original sources
PubMed1995

Cardiopulmonary complications during laparoscopy: two case reports.

Laparoscopic surgery is growing in popularity. As a result, laparoscopic procedures are being done on a broader and older patient population. These patients may have underlying cardiopulmonary disease that predisposes them to complications not seen in younger patients. Anesthesiologists should be aware of this possibility and of the problems inherent to the pneumoperitoneum necessary for laparoscopy. We present two cases involving elderly patients to illustrate cardiopulmonary complications that can occur during establishment or maintenance of the increased intra-abdominal pressures required for laparoscopic surgery. The first case describes a patient who developed bradycardia and asystole during insufflation for a laparoscopic hernia repair. The second case involves severe hypercarbia and a pneumothorax due to massive subcutaneous emphysema that developed during a laparoscopic colon resection.

Adenocarcinoma↗
PubMed1995

Effects of 2164U90 on ileal bile acid absorption and serum cholesterol in rats and mice.

2164U90, [(3R,5R)-trans-3-butyl-3-ethyl-2,3,4,5-tetrahydro-5-phenyl-1,4- benzothiazepine 1,1-dioxide], was found to be a potent inhibitor of the ileal bile acid active transport system. In vitro, 2164U90 decreased uptake and active transport of taurocholic acid by rat everted ileal sacs with IC50s of 4.0 microM and 1.5 microM, respectively. In vivo, 2164U90 produced dose-dependent increases in 23,25-75Se-labeled homocholic acid taurine (SeHCAT) fecal excretion in rats and mice at doses of 3-30 mg/kg and 1-10 mg/kg, respectively. In rats, 30 mg/kg 2164U90 was equivalent to 500 mg/kg cholestyramine. Two days oral administration of 10 mg/kg 2164U90 to rats decreased the bile concentrations of total bile acids 42%, orally administered [3H]taurocholic acid ([3H]TC) 82%, and cholesterol 35%. Cholestyramine (500 mg/kg) had effects similar to 2164U90 on total bile acid and orally administered [3H]TC concentrations but had no effect on biliary cholesterol. The hypocholesterolemic activity of 2164U90 was determined in cholesterol-cholic acid-fed rats and cholesterol-cholic acid-coconut oil-fed mice. 2164U90 inhibited the dietary-induced increase in dextran sulfate-precipitable lipoprotein cholesterol (VLDL+LDL) at doses comparable to doses needed to increase the fecal excretion of bile acids. These data indicate that 2164U90 decreases bile acid absorption by inhibiting the ileal bile acid active transport system, resulting in hypocholesterolemic activity.

Administration, Oral↗
PubMed1995

Inhibition of ileal sodium-dependent bile acid transport by 2164U90.

Inhibition of the ileal bile acid active transport system, previously shown to be mechanism underlying the hypocholesterolemic activity of 2164U90 in rodents, was further characterized in isolated intestinal preparations from three species. 2164U90 inhibited sodium-dependent transport of taurocholic acid by Caco-2 cells and by monkey and human ileal brush border membrane vesicles in a concentration-dependent manner with IC50s of 7 microM, 5 microM, and 2 microM, respectively. In rat ileal brush border membrane vesicles, 2164U90 was a competitive inhibitor of sodium-dependent taurocholic acid uptake with an estimated Ki of 1.8 +/- 0.2 microM. In anesthetized rats, 5 microM 2164U90 placed in the isolated distal ileum with 3 mM [3H]taurocholic acid decreased ileal uptake, transport into the bile, and transport rate of taurocholic acid by 31-35%. Stereospecificity of inhibition by 2164U90 was demonstrated by the relative inactivity of three other possible stereoisomers in rat ileal sacs and brush border membrane vesicles. 2164U90 did not inhibit sodium-dependent glucose transport by monkey jejunal brush border membrane vesicles, indicating that 2164U90 may be specific for the bile acid transporter. These results suggest that 2164U90 is a potent, selective, stereospecific, competitive inhibitor of the sodium-dependent bile acid transporter in the ileal mucosal cell brush border membrane.

Animals↗
PubMed1991

Studies on muscle cells isolated from Schistosoma mansoni: a Ca(2+)-dependent K+ channel.

Muscle cells from adult male Schistosoma mansoni have been isolated using a combination of papain digestions and mechanical dissociation procedures. The muscle fibres isolated in this way lacked nuclei but they did contract and relax in response to high [K+], a response which was blocked in the presence of Co2+. From this we conclude that the isolation procedure yields viable muscle fibres useful for physiological studies. Patch-clamp recordings taken from the isolated fibres show a variety of discrete ionic conductances. In inside-out patches one prominent channel was a Ca(2+)-activated K+ channel with a conductance of 195 pS and a selectivity greater than 10:1 for K+ over Na+, Cs+ or NH4+. Percentage open time was dependent on [Ca2+] at the intracellular face. With [Ca2+] at 1 microM or greater percentage open time was greater than 95%; at 0.1 microM it was less than 2%. No voltage sensitivity could be detected in the voltage range from -50 to -10 mV membrane potential. Ba2+ (10 mM), but neither tetraethylammonium nor 3,4-diaminopyridine blocked the channel from the intracellular face. This Ca(2+)-activated K+ channel in the muscle membrane of this acoelomate animal is similar in most respects to the maxi-K+ channels which have been described in a variety of cells from more highly evolved animals.

Animals↗
PubMed1990

Blood irradiation: rationale and technique.

Upon request by the local American Red Cross, the Savannah Regional Center for Cancer Care irradiates whole blood or blood components to prevent post-transfusion graft-versus-host reaction in patients who have severely depressed immune systems. The rationale for blood irradiation, the total absorbed dose, the type of patients who require irradiated blood, and the regulations that apply to irradiated blood are presented. A method of irradiating blood using a linear accelerator is described.

Blood↗
PubMed1990

In vivo transport kinetics and distribution of taurocholate by rat ileum and jejunum.

The transport kinetics and distribution of taurocholate (TC) from the ileum and jejunum were evaluated in anesthetized Sprague-Dawley rats. Uptake and transport kinetics were determined after simultaneous administration of equimolar solutions of [3H]taurocholic acid ([3H]TC) in the ileum and [24-14C]taurocholic acid ([14C]TC) in the jejunum of anesthetized rats. At TC concentrations between 0.3 and 15 mM, total ileal absorption exceeded jejunal absorption 15- to 25-fold. The apparent Km and Vmax for ileal absorption of TC were 5.6 mM and 65.5 nmol.min-1.cm-1, respectively. Tissue distribution studies following uptake from the ileum and jejunum were done with 75Se-labeled homocholic acid taurine (75Se-HCAT). In the ileum, 82% of the 75Se-HCAT removed from the lumen was found in the bile, 10.6% was found in the ileal wall, and 7.3% was found in the liver. In the jejunum, 24.1% was found in bile, 0.6% was found in the liver, and 75.3% remained in the jejunal wall. These data show that the ileum is much more efficient and better equipped than the jejunum to take up and transport TC at concentrations up to 15 mM.

Animals↗
PubMed1988

Midazolam infusion and the benzodiazepine antagonist flumazenil for sedation of intensive care patients.

ICU patients often require sedation. Midazolam (M), a new imidazobenzodiazepine, features rapid onset and rapid elimination time. Flumazenil (Ro 15-1788) is a new benzodiazepine antagonist. We studied the efficacy and safety of M by continuous infusion in 28 ICU patients: 16 post major surgery, and 12 medical patients, aged 20-77 years. M was administered as a loading dose of 0.05-0.15 mg/kg per min followed by continuous infusion of 0.05-0.1 mg/kg per h titrated to maintain patients asleep but arousable. M was administered for up to 14 days in doses of 1-15 mg/h and cumulative doses of up to 1915 mg. No untoward effects were noted except for slight decreases in blood pressure following the loading dose. ACTH challenge tests performed before and 24 h or more following the start of M showed no depression of adrenal responsivity. All patients meeting weaning criteria were weaned off mechanical ventilation while still on M. In 13 patients extubation was performed immediately after M was stopped, and flumazenil (0.38 +/- 0.27 mg, i.v.) given until full awakening. Patients remained awake yet calm. Vital signs remained stable after flumazenil. Midazolam by continuous infusion appears to be a safe and effective mode of sedation in ICU patients. Flumazenil may increase the flexibility and safety of this mode of sedation.

Adult↗
PubMed1987

Evaluation of the hypolipidemic activity of xenalipin in experimental animals.

Xenalipin (4'-trifluoromethyl-2-biphenylcarboxylic acid) is a chemically novel compound which has been found to be an effective hypolipidemic agent in two animal species. Significant reductions in serum cholesterol and triglycerides were observed in cholesterol-cholic acid-fed rats following oral doses of 10-30 mg/kg/day. Xenalipin was considerably more potent than clofibrate, nicotinic acid, and cholestyramine in the same model. Lipoprotein analysis showed that xenalipin reduced cholesterol and protein content in very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and low density lipoprotein (LDL). Triglycerides were reduced in VLDL and IDL. Xenalipin was also effective in reducing serum cholesterol and triglyceride concentrations in normocholesterolemic rats. In diet-induced hypercholesterolemic African green monkeys, xenalipin at oral doses of 15-60 mg/kg b.i.d. reduced serum LDL-cholesterol concentrations. These results suggest that xenalipin has a profile of activity which would be beneficial in therapy for hyperlipidemia.

Animals↗
PubMed1987

Colostomy or ileostomy after colorectal anastomosis?: a randomised trial.

Sixty one patients were entered in a randomised trial to compare transverse loop colostomy with loop ileostomy after a colorectal anastomosis thought to be at risk of dehiscence. Radiologically proven breakdown of the colorectal anastomosis occurred in 13% of these selected patients and most frequently in the colostomy group. Ileostomies functioned earlier than colostomies (P less than 0.001) but there was no other significant difference in outcome between the groups. In 52 patients intestinal continuity was restored by excision of the stoma within a month of construction with no difference in morbidity between the two groups. A loop ileostomy, closed as soon as the colorectal anastomosis has healed, is recommended as an alternative to transverse colostomy.

Aged↗
PubMed1986

Specificity of the surface aminopeptidase in Moniliformis moniliformis (Acanthocephala).

The hydrolysis of various oligopeptides in solution by intact Moniliformis moniliformis was examined using paper chromatographic analysis of the incubation medium. In the presence of transport inhibitors, the respective peptide sub-units and/or amino acid residues accumulated in the bathing medium. Only peptides with serine, methionine, leucine or alanine at the NH2-terminal end of the peptide were hydrolysed. There was no hydrolysis when these amino acids were located internally or at the COOH-terminus indicating genuine aminopeptidase activity of the class, alpha-aminoacylpeptide hydrolase. Hydrolysis was negligible when the NH2-terminus was arginine, aspartic acid, glutamic acid, glycine, histidine, lysine, phenylalanine, proline, tryptophan, tyrosine, or valine. In separate experiments, mediated uptake of 0.1 mM 3H-leucine by the worms in 2 min was inhibited 100% by 5 mM unlabelled leucine or tri-serine, but only partially inhibited by 5 mM Ser-Gly (66%), 10 mM Ser-Gly (74%), 5 mM Leu-Leu (69%), 10 mM Leu-Leu (70%), 5 mM Leu-Gly (58%) or 5 mM Met-Met (69%). Because the inhibitions produced by 5 mM Leu-Leu plus 5 mM Met-Met (79%) or 5 mM Leu-Leu plus 5 mM Ser-Gly (76%) were not additive, a single enzyme is indicated. The name serine aminopeptidase is proposed because of its preference for serine.

Acanthocephala↗
PubMed1985

A randomized trial to compare single with multiple phenol injection treatment for haemorrhoids.

One hundred and twenty consecutive patients were entered into a randomized trial of single versus multiple phenol injection for the treatment of haemorrhoids. Follow-up at 3 and 12 months was available in 105 patients (56 in the single group and 49 in the multiple group). The results have shown that injection therapy, whether this be single or multiple, is an extremely effective form of therapy for patients with first or second degree haemorrhoids.

Adult↗
PubMed1975

Determinants of visual attention in real-wound scenes.

The present study examined the saliency of size, movement, and human content variables in visual selective attention. Ss named stimuli present in motion pictures of real world scenes or in animated cartoon controls during a 15-sec. exposure period. Regardless of the type of presentation that they saw, Ss tended to name large and/or moving stimuli more often than small and/or nonmoving stimuli. Also, small human stimuli were named more frequently than small nonhuman stimuli, while there were no differences between the frequencies with which large human and nonhuman stimuli were named. The order in which Ss named stimuli was not related to either the size, movement, or human content variables. Results are discussed in terms of the generalizability of the results of previous studies to conditions simulating the real world.

Attention↗