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Biomedical subjects

J G Muir

Publications and source records attributed to J G Muir.

18 recordsLinked to original sources
PubMed1992

Measurement of resistant starch: factors affecting the amount of starch escaping digestion in vitro.

We developed an in vitro assay system that mimics the physiological conditions for starch digestion. In this system all undigested starch was termed resistant starch (RS). The richest sources of RS were firm bananas and roasted chickpeas. Different food-processing techniques produced different amounts of RS. RS in uncooked oats (0.161 g/g dry wt) and firm bananas (0.247 g/g dry wt) was reduced by cooking to 0.028 and 0.032 g/g dry wt, respectively. Cooling boiled potato overnight at 4 degrees C produced a 2.8-fold increase in the amounts of RS. Whole rice contained more RS than did ground rice whereas grinding did not affect amounts of RS in roasted chickpeas. Amounts of RS in food decreased with increased chewing, indicating that chewing can also affect the amount of starch escaping digestion. This assay may be useful in predicting which foods and processing techniques result in high amounts of starch escaping digestion in the small intestine.

Dietary Carbohydrates↗
PubMed1990

Large volumes of apple juice preoperatively do not affect gastric pH and volume in children.

The effect on gastric pH and volume of 0, 6 and 10 ml.kg-1, of apple juice given 2.5 hours before surgery to children aged five to ten years was investigated in this prospective, randomized, single-blind study. Gastric contents were aspirated after induction of anaesthesia, and the volume measured. The pH of the gastric aspirate was then assessed using pH paper. Neither gastric volume nor pH immediately following the induction of general anaesthesia were significantly different among the three groups. Gastric volumes after 0, 6 and 10 ml.kg-1, of juice averaged (mean +/- SD) 0.45 +/- 0.31, 0.66 +/- 0.79 and 0.71 +/- 0.76 ml.kg-1, respectively; gastric pH averaged 1.7 +/- 0.6, 1.7 +/- 0.6 and 1.8 +/- 0.8, respectively. On the basis of questions asked immediately before induction of anaesthesia, patients who drank 6 ml.kg-1 of apple juice had decreased thirst and were less irritable and upset before anaesthesia than those who had not (P less than 0.05). It is concluded that drinking large volumes of clear apple juice 2.5 hours before scheduled surgery does not have a measurable effect on gastric volume and pH and may offer benefits such as improved patient comfort.

Beverages↗
PubMed1989

The effect of preoperative apple juice on gastric contents, thirst, and hunger in children.

The effect of 3 ml.kg-1 of apple juice given 2.6 +/- 0.4 hours preoperatively was investigated in 80 healthy children of ages five to ten years in this prospective, randomized, single blind study. The children who drank apple juice preoperatively had decreased gastric volume, thirst, and hunger (p less than 0.05). The gastric volume in the control group was 0.43 +/- 0.46 ml.kg-1 and in the patients who received apple juice the gastric volume was 0.24 +/- 0.31 ml.kg-1. The gastric pH was not significantly different, with the control group's gastric pH being 1.7 +/- 0.6 and the treated group's pH was 2.2 +/- 1.2. Further studies of the effects of different volumes and timing of preoperative clear fluids are indicated in paediatric patients.

Beverages↗
PubMed1988

Phosphatidylcholine synthesis in platelets is stimulated by diacylglycerol but not by phorbol ester.

The biosynthesis of phosphatidylcholine (PC) in platelets was followed by measuring the incorporation of 32Pi. Incorporation into PC was stimulated by treatment with Clostridium perfringens phospholipase C or with the synthetic diacylglycerol sn-1,2-dioctanoylglycerol. However, neither the phorbol ester tumour promoter 12-O-tetradecanoylphorbol-13-acetate or thrombin stimulated 32Pi incorporation into PC. We conclude that phorbol ester does not stimulate the hydrolysis of PC to diacylglycerol in platelets.

Blood Platelets↗
PubMed1987

Bombesin and phorbol ester stimulate phosphatidylcholine hydrolysis by phospholipase C: evidence for a role of protein kinase C.

Bombesin caused a marked stimulation of 32Pi into phosphatidylinositol (PI), with no apparent lag, and into phosphatidylcholine (PC), after a lag of about 20 min. Stimulation was blocked by the bombesin receptor antagonist, [D-Arg1, D-Pro2, D-Trp7,9, Leu11] substance P, indicating that the effects on both PI and PC were mediated through the same receptor. The tumor-promoting phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA) and dioctanoylglycerol (diC8) both directly activate protein kinase C and in this report were shown to stimulate 32Pi incorporation into PC but not into Pl. In addition, TPA stimulated the release of [3H]choline and [3H]phosphocholine and the accumulation of [3H]diacyglycerol from prelabelled cells. These results strongly suggest that TPA activates a phospholipase C specific for PC. Pretreatment of cells with phorbol-12, 13-dibutyrate (PDBu) for 24 h depleted cellular protein kinase C activity and inhibited the ability of TPA to induce these effects suggesting a direct involvement of protein kinase C. Similarly the bombesin stimulation of 32Pi into PC and of [3H]choline and [3H]phosphocholine release was inhibited by PDBu pretreatment. DiC8 and, to a lesser extent, TPA stimulated the translocation of CTP:phosphocholine cytidylytransferase from the cytosolic to the particulate fraction. DiC8 also stimulated this translocation in cells depleted of protein kinase C. It was concluded that both bombesin and TPA activated protein kinase C leading to activation of a phospholipase C specific for PC.

Animals↗
PubMed1987

Direct evidence for phorbol ester-stimulated accumulation of diacylglycerol derived from phosphatidylcholine.

A fluorescent analog of phosphatidylcholine, 1-acyl-2-[N-(4-nitrobenzo-2-oxa-1,3-diazole)aminocaproyl]phosphatidyl choline (NBD-PC), was inserted into the plasma membrane of HeLa cells. Treatment of NBD-PC-labelled cells with the tumour promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), resulted in the production of fluorescent diacylglycerol, 1-acyl-2-[N-(4-nitrobenzo-2-oxa-1,3-diazole)-aminocaproyl]diacylglycerol (NBD-DG), suggesting that phorbol ester activates a PC-specific phospholipase C in these cells. Furthermore pretreatment of cells with phorbol-12,13-dibutyrate for 24 h, a process which depletes cellular protein kinase C activity, inhibited the ability of TPA to induce this effect. These results suggest that TPA stimulation of a phospholipase C specific for PC in HeLa cells is mediated via protein kinase C.

Cell Membrane↗
PubMed1986

Mimicry of phorbol ester responses by diacylglycerols. Differential effects on phosphatidylcholine biosynthesis, cell-cell communication and epidermal growth factor binding.

The biosynthesis of phosphatidylcholine (PC) in HEL-37 cells was followed by measuring the incorporation of [32P]Pi into PC. Incorporation was stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) and by the synthetic diacylglycerol, sn-1,2-dioctanoylglycerol (diC8), but not by sn-1-oleoyl-2-acetylglycerol or sn-1,2-dihexanoylglycerol (diC6). DiC8 was rapidly metabolised by HEL-37 cells to the corresponding PC and phosphatidic acid derivatives. diC8, diC6 and oleoylacetylglycerol effectively displaced [3H]phorbol-12,13-dibutyrate bound to a soluble cell extract from HEL-37 cells, but only diC8 was able to displace the labelled phorbol ester from prelabelled cells. TPA, diC8, diC6 and oleoylacetylglycerol were all effective inhibitors of 125I-labelled epidermal growth factor binding to, and gap junctional communication between, HEL-37 cells. It is concluded that only cell-permeable diacylglycerols stimulate PC biosynthesis which may therefore require interaction with membranes other than the plasma membrane.

Animals↗
PubMed1985

Effect of orally administered nadolol on the intraocular pressure in normal volunteers.

Forty six normal volunteers were randomly assigned in double-blind fashion to once daily orally administered nadolol 10, 20, 40, or 80 mg for five days. Significant and dose related intraocular pressure (IOP) reductions (range 20-40%) were demonstrated both at three hours and 24 hours post dosing (p less than 0.001, all dosages). The reductions in IOP were dose related (p less than 0.05). One subject (in the 10 mg group) failed to show a significant intraocular pressure reduction. Significant reductions in blood pressure and heart rate also were recorded at all dose levels (with the exception of diastolic pressure in the 10 mg group), though considerably less in degree than IOP reductions. Two subjects (20 mg and 80 mg groups) experienced known side effects of beta blocker therapy necessitating termination of the drug, and four others experienced mild side effects but had no difficulty completing the study. The results have prompted further investigation of the usefulness of low doses of oral nadolol as therapy in chronic simple glaucoma patients.

Administration, Oral↗
PubMed1975

Properties of a free and a solubilized form of bound alpha,alpha-trehalase purified from honey bee thorax.

The free and bound forms of alpha,alpha-trehalase (EC 3.2.1.28) of the honey bee thorax were separated and the bound enzyme was solubilized by raising the pH to 8.0 for 10 h. Both enzymes were purified. They were homogeneous as determined by several electrophoretic criteria. It was found that the two enzymes had very similar Km's (each about 0.89 mM), Vm's (53.2 and 54.3 U/mg for free and solubilized, respectively), inhibition characteristics, specificities (both only hydrolyzed alpha,alpha-trehalose), pH maxima (each had maxima at about 3.5 and 6.5), molecular weights (65,000), isoelectric points (5.1), reactivities to sulfhydryl reagents, electrophoretic mobilities, activation energies (about 12.8 kcal/mol), and similar stabilities to heat, pH, and urea. Some significant differences between the two enzymes were, however, found: the solubilized alpha,alpha-trehalase floated at 70% saturation of ammonium sulfate while the free alpha,alpha-trehalase did not; the solubilized alpha,alpha-trehalase did not dissociate into subunits as readily as did the free one; and the solubilized alpha,alpha-trehalase was found to bind more readily to a hydrophobic grouping than the free enzyme. In addition to these comparisons, three new findings relating to thorax alpha,alpha-trehalases are reported. (1) Thorax alpha,alpha-trehalases are strongly inhibited by beta-glucosides (Ki values of about 8 x 10(-4) M); (2) under certain conditions thorax alpha,alpha-trehalases from honey bees dissociated into subunits of one-half the normal molecular weight; (3) honey bee thorax alpha,alpha-trehalases have unusual biphasic pH activity profiles.

Animals↗
PubMedDate not supplied

Summary of worldwide clinical trials of aztreonam in patients with lower respiratory tract infections.

Aztreonam was administered to 226 patients with lower respiratory tract infections--primarily pneumonia (181 patients)--due to gram-negative bacilli. The clinical response rate was 93%, and the microbiologic cure rate was 78%. Most patients received 1-g or 2-g intravenous doses of aztreonam three times daily for at least five days. Ninety-eight of the 226 patients were involved in a randomized comparison of aztreonam with tobramycin; the latter drug was administered to a group of 34 patients. The overall microbiologic cure rates for the two drugs were 86% and 71%, respectively. Aztreonam is effective for the treatment of lower respiratory tract infections due to susceptible gram-negative bacilli.

Aztreonam↗
PubMedDate not supplied

Summary of worldwide clinical trials of aztreonam in patients with urinary tract infections.

Aztreonam was administered to a total of 681 patients with urinary tract infections due to susceptible gram-negative bacteria; 56 patients received a single 1-g intramuscular dose for acute uncomplicated cystitis, and 625 patients received multiple parenteral doses (usually a five-day course of 1 g two or three times daily) for a variety of urinary tract infections, including pyelonephritis, cystitis, prostatitis, and epididymitis. Microbiologic cure was achieved in 84% of patients in the single-dose study and in 85% of patients in the multiple-dose studies. In the latter studies the microbiologic cure rates for infections with Escherichia coli, the Klebsiella-Enterobacter-Serratia group, and Pseudomonas aeruginosa were 87%, 90%, and 76%, respectively. In a comparative study of aztreonam and cefamandole, the overall microbiologic cure rates were 89% and 80%, respectively. Of the 625 patients receiving multiple-dose therapy, 149 had urinary tract infections due to multiply drug-resistant bacteria; among these patients the microbiologic cure rate was 93%. Aztreonam constitutes effective therapy for urinary tract infections due to susceptible gram-negative bacilli.

Adult↗