PubMed Health⌕ Search

Biomedical subjects

R G Willis

Publications and source records attributed to R G Willis.

18 recordsLinked to original sources
PubMed2006

Urethral dilatation in women: urologists' practice patterns in the UK.

INTRODUCTION: Review of the literature reveals little evidence to prove the efficacy of urethral dilatation for adult women with various lower urinary tract complaints. We conducted a postal survey to ascertain the actual practice of urethral dilatation among urologists in the UK. MATERIALS AND METHODS: A questionnaire was mailed to 428 consultant urologists listed as full members of the British Association of Urological Surgeons. The questionnaire consisted of 8 items about urologists' perception of indications, efficacy, and the need for repeated dilatation and anaesthesia. RESULTS: The questionnaire response rate was 42%. Although urethral stenosis was the most common indication (97%), the majority of urologists (69%) indicated that fewer than 25% of patients had evidence of stenosis. Overall, 61% of urologists performed dilatation 7 times or more during the last year and 55% believed that less than half of the patients experienced long-term improvement. CONCLUSIONS: Despite the lack of strong evidence to support the use of urethral dilatation in women, many urologists continue to find it a useful tool in approaching women with lower urinary tract complaints.

Adult↗
PubMed1998

Chemical composition of smoke produced by high-frequency electrosurgery in a closed gaseous environment. An in vitro study.

BACKGROUND: High-frequency (HF) electrocoagulation and cutting procedures produce smoke by high-temperature pyrolysis of tissues. As distinct from the experience of conventional surgery, electrosurgical smoke is produced in a closed gaseous environment during laparoscopic operations. As a result, toxic chemicals may be absorbed into the circulation. The effects of this absorption are not known. Furthermore, the chemical composition of electrosurgical smoke produced in an anoxic environment may be different from that produced in air. METHODS: Smoke was produced in vitro by HF electrocutting of fresh porcine liver in helium, CO2, and air-saturated closed environments. Smoke samples were collected and analyzed by gas chromatography-mass spectrometry (GC-MS). RESULTS: The chemical constituents of electrosurgical smoke produced in air, CO2, and helium were similar. To date, 21 chemicals, some highly toxic, have been identified in the electrosurgical smoke produced in a closed environment. These consist of hydrocarbons, nitriles, fatty acids, and phenols. CONCLUSIONS: Electrosurgical smoke produced in a closed environment contains several toxic chemicals. The effects of these on cell viability, macrophage, and endothelial cell activation are not known but are being investigated. Meantime, measures to reduce smoke and evacuate it during endoscopic surgery are advisable.

Air Pollutants↗
PubMed1991

In vitro studies on the deacetylation-reacetylation of arylamides and the transacetylation of arylamines by human and rat whole blood.

Human and rat whole blood were shown to metabolize the aromatic amides acetanilide and phenacetin by deacetylation followed by reacetylation in vitro. Derivatives of the parent compounds labelled with deuterium in the N-acetyl group produced non-labelled material after incubation. The reaction was monitored by capillary gas chromatographic-mass spectrometric (GC-MS) analysis. There was no significant difference in the acetyl group exchange of these substrates using blood samples donated by non-diabetic volunteers or Type 2 diabetic patients (respective mean +/- SEM values = 4.0 +/- 0.2% and 4.2 +/- 0.3% for trideuteroacetanilide, 6.2 +/- 0.6% and 6.1 +/- 0.3% for trideuterophenacetin). Increasing the glucose concentration in the incubation medium by 50 mmol/L significantly (P less than 0.01) increased deacetylation-reacetylation of trideuteroacetanilide in each group (4.6 +/- 0.2% and 4.7 +/- 0.2% for non-diabetic and diabetic subjects, respectively). In rat blood the amount of deacetylation-reacetylation was much higher: 7.2 +/- 0.6% and 8.3 +/- 0.7% for trideuteroacetanilide and trideuterophenacetin, respectively. Induction of experimental diabetes using streptozotocin did not significantly change the extent of deacetylation-reacetylation of either deuterated substrate (10.1 +/- 2.1% and 9.5 +/- 1.1%). Elevation of the incubation glucose concentration by 50 mmol/L produced an increase in acetyl group exchange (for trideuteroacetanilide) in diabetic (14.3 +/- 2.2%) and non-diabetic (10.6 +/- 1.0%) rats. The donation of acetyl groups (transacetylation) was observed after incubation of blood samples from both diabetic and non-diabetic human subjects and rats with trideuterophenacetin and a molar excess of aniline. This reaction significantly (P less than 0.001) decreased the acetyl group exchange of trideuterophenacetin (these values were 4.5 +/- 0.4% and 3.4 +/- 0.6% using samples from non-diabetic human subjects and rats, respectively) and demonstrated the ability of whole blood to catalyse transacetylation (acetyl-CoA-independent acetylation). There was correlation between the amount of (unlabelled) acetanilide produced by acetylation with acetyl-CoA and the percentage present as trideuteroacetanilide. The proportion of trideuteroacetanilide was higher using rat blood (e.g. the values for non-diabetic subjects were 25.5 +/- 1.7% vs 8.5 +/- 0.3%; P less than 0.001) although the total amount of acetanilide produced was lower (0.54 +/- 0.14 nmol vs 1.82 +/- 0.23 nmol; P less than 0.05) than that observed using human blood.

Acetanilides↗
PubMed1990

Identification of triacylglycerols by high-performance liquid chromatography-gas-liquid chromatography and liquid chromatography-mass spectrometry.

Triacylglycerols from rat adipose tissue were chromatographed by high-performance liquid chromatography (HPLC), with a gradient of propan-2-ol in acetonitrile as the mobile phase. Fractions of the material eluting from the column were collected and analysed by automated gas - liquid chromatography of the fatty acid methyl esters obtained after transmethylation. Triacylglycerols were identified by using a combination of their fatty acid content and elution time from the HPLC column. Fractions corresponding to whole peaks or groups of peaks were also collected and re-chromatographed on a liquid chromatography - mass spectrometry system equipped with a belt interface. For most triacylglycerols, good agreement was obtained between the two methods, although mass spectrometric identification of the early eluting peaks was complicated by poor resolution of the triacylglycerols on the HPLC system.

Adipose Tissue↗
PubMed1988

Stable isotopes as probes for the metabolism of acetanilide in man and the rat.

Acetanilide with the three hydrogens of the acetyl group replaced by deuterium was administered to 9 human volunteers (50 mg p.o.) and 5 male Sprague-Dawley rats (10 mg kg-1 p.o. and 100 mg kg-1 p.o.) and urine samples collected for 8 and 48 h, respectively. Capillary gas chromatography/mass spectrometry (GC/MS) was used to determine if the major metabolite was deuterated paracetamol or a mixture of this compound with paracetamol produced by deacetylation followed by reacetylation. Acetyl group exchange of the parent compound was also studied. Conjugates of the metabolite were hydrolysed and the free compound derivatized to an O-propionyl ester before GC/MS analysis. Paracetamol containing no deuterated acetyl group was detected in all studies, together with the labelled metabolite. The mean ratio of deuterated to unlabelled paracetamol in man was approximately 8:1 and was independent of acetylator status. The acetyl group exchange measured in the rat was time-dependent but was always significantly higher than in man. The mean ratios of deuterated to unlabelled paracetamol in urine samples collected 0-4 h and 24-48 h after administration of the higher trideuteroacetanilide dose to the rats were approximately 2:1 and 4:1, respectively.

Acetanilides↗
PubMed1986

A comparison of methods for the high-performance liquid chromatographic and capillary gas-liquid chromatographic analysis of fatty acid esters.

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method for the analysis of free fatty acids in plasma was compared with a method using capillary gas-liquid chromatography (GLC). The same extraction procedure was used for both assays. In the RP-HPLC method, the acids were separated as their anthrylmethyl esters on a C18 reversed-phase column, and detected by fluorescence. The coupling agent 2-bromo-1-methylpyridinium iodide was used with 9-(hydroxymethyl)anthracene. A mobile phase of acetonitrile-water (98:2) was used with flow programming. The derivatives of the C14:0, C16:1 and C18:2 acids could not be fully resolved. For capillary GLC, the acids were separated as their methyl esters following on-column injection into a 25-m OV-101 glass capillary column and detected using flame ionization detection. The esterifying agent used was diazomethane. The C18:2 and C18:3 esters were not fully resolved. The precision and sensitivity of both methods were similar. In an application of the methods, the free fatty acid concentrations in the plasma of a group of diabetic patients and their age-matched controls were estimated. Fatty acid concentrations tended to be higher in the diabetic group but, in the small number of patients studied, wide inter-individual variations prevented a significant difference from being detected. Estimates of individual fatty acids were higher by the RP-HPLC method. The identity of the acids in the extract was confirmed by gas chromatography-mass spectrometry of their methyl esters.

Chromatography, Gas↗
PubMed1985

Liquid chromatography/mass spectrometry of fatty acids as their anthrylmethyl esters.

The mass spectra of a series of saturated and unsaturated fatty acids have been recorded as their anthrylmethyl esters using a liquid chromatographic mass spectrometric interface. The spectra show an intense peak for the aromatic nucleus, and a molecular ion. The liquid chromatographic/mass spectrometric separation was performed on a reverse phase column using a solvent system of acetone + acetonitrile. While a complete separation of the fatty acids known to occur in man was not achieved, the recognition of all of these acids is possible using a scanning mode or by ion monitoring.

Anthracenes↗
PubMed1984

Are bile bacteria relevant to septic complications following biliary surgery?

Bile bacteriology, wound sepsis and the effect of prophylactic antibiotics have been studied in a controlled prospective double blind randomized trial on 375 patients undergoing elective cholecystectomy at a district general hospital. We have examined the overall prevalence of bacteria in bile and have identified several factors associated with an increased incidence. The identity of organisms isolated from a total of 21 patients with infected wound swabs was compared with isolates from the bile at operation, and in only two instances was there a correlation. Cephazolin, given either pre-operatively, or into the wound, reduced wound infection rates compared with a control group (from 11.8 to 2.4 per cent, P less than 0.005). We conclude that the majority of wound infections in this series were caused by organisms from the patients' skin or exogenous sources, rather than by bacteria from the biliary system.

Adolescent↗