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Biomedical subjects

G Smith

Publications and source records attributed to G Smith.

At least 739 records · Page 41Linked to original sources
PubMed1984

Density-dependent mechanisms in the regulation of Fasciola hepatica populations in sheep.

Populations of Fasciola hepatica infecting sheep are regulated by at least 3 density-dependent processes. Parasite deaths due to parasite-induced primary host mortality, fluke fecundity and asexual multiplication in the intermediate snail host, Lymnaea truncatula, vary according to the intensity of infection. Empirical and theoretical evidence is used to assess the extent to which each of these processes in turn affects parasite population numbers.

Animals↗
PubMed1984

Long-term outcome after repair of fractured neck of femur. Comparison of subarachnoid and general anaesthesia.

One hundred and forty-eight patients undergoing "pin-and-plate" repair of fractured neck of femur received either subarachnoid blockade or general anaesthesia. The patients were followed up for 1 year after surgery. At the end of the year, 34% had died and 50% had returned home. Twelve per cent were either in hospital or in institutional care; 4% were lost to follow up. The mean duration of acute plus convalescent hospital bed occupancy was 84.4 days. There was a significantly lower mortality in the subarachnoid anaesthetic group by 14 days after surgery. The majority of the deaths in the general anaesthetic group were clustered between 6 and 16 days. However, at the end of 2 months the mortality rates were similar in both groups. It is conceivable that the difference in the distribution of deaths between the groups was a result of thrombo-embolism.

Aged↗
PubMed1984

Pharmacokinetics of single-dose i.v. morphine in normal volunteers and patients with end-stage renal failure.

Morphine 0.125 mg kg-1 was administered i.v. to 11 normal subjects and nine patients with chronic renal failure requiring regular haemodialysis. Plasma morphine concentrations were measured using high pressure liquid chromatography (HPLC). Although there was considerable individual variation in both groups, mean plasma concentrations of morphine were significantly higher in the patients with renal failure for 15 min after administration. The decay of plasma concentration fitted a three-compartment mamillary pharmacokinetic model in all subjects. Derived values (mean +/- SEM) of T 1/2 alpha, volume of distribution of the second compartment (V2), total volume of distribution at steady state (Vss) and transfer rate constant from the first to the second compartment (k12), were significantly different between groups. Mean values of terminal elimination half-life (T 1/2 gamma) and total body clearance were similar in the two groups. It was concluded that elimination of unchanged morphine is not impaired significantly in patients with chronic renal failure, although accumulation of morphine-3-glucuronide probably occurs. Although the pharmacological effect of morphine is not related temporally to plasma morphine concentrations, the higher values in patients with renal failure may be implicated in their increased sensitivity to the drug.

Adult↗
PubMed1984

Pharmacokinetics and analgesic effect of slow-release oral morphine sulphate in volunteers.

Sustained-release oral morphine sulphate (MST) 20 mg was administered to 11 healthy volunteers. Mean peak plasma morphine concentration was 14.8 ng ml-1, and occurred at a mean time of 142.5 min after ingestion. Analgesia assessed by an ischaemic forearm pain test increased to a maximum approximately 40 min after the calculated peak plasma concentration of morphine had been achieved, and remained greater than control values as plasma morphine concentration decayed. However, there was not a significant correlation between analgesia and plasma morphine concentration. This may result from delay in brain penetration by morphine. The mean systemic availability of morphine in the first 7 h after administration of MST was 18.3%.

Administration, Oral↗
PubMed1984

Clinical trial with commercial aspheric aphakic lenses.

A clinical trial with 11 subjects was conducted to compare the Armorlite Multiple Drop, the Signet Hyperaspheric, the Sola Hi-Drop, and the American Optical Fulvue types of aspheric aphakic lenses. Reasonable off-axis visual acuities were obtained with the Signet, Sola, and Fulvue types, but poor visual acuities were found with the Armorlite type. Similar visual field limits were found with the armorlite, Signet, and Sola types. Considerably larger limits were found with the Fulvue type than with the other types. However, subjects failed to appreciate these larger limits; this was attributed to the extremely poor image quality near the edge of the visual field with this lens type. Some subjects disliked the poor off-axis image quality with the Armorlite lens type, and it had poor acceptance relative to the other types. Concerning subjective perception of weight, cosmetic appearance, and visual field size, and subjective evaluation of performance of everyday activities, there were no significant differences between lens types. It was concluded that reducing lens off-axis power errors, corresponding to the rotating eye, should remain the most important principle of aphakic spectacle lens design.

Aged↗
PubMed1984

Meridional variations of corneal shape.

The corneal shape of 196 eyes was determined by photokeratoscopy and subsequent fitting of a conicoid equation to four individual corneal meridians. This conicoid was found in almost all instances to be ellipsoidal, with the asphericity not varying between meridians. The corneal radius of curvature did vary as expected between meridians. The radii of curvature of these corneal meridians also varied with the age of the subjects, resulting in reduced corneal astigmatism, while the asphericity of each meridian did not vary substantially with age.

Adolescent↗
PubMed1984

Non-parenteral postoperative analgesia. A comparison of sublingual buprenorphine and morphine sulphate (slow release) tablets.

Sixty-nine patients undergoing upper and lower abdominal surgery were studied after operation to compare the analgesic effects of sublingual buprenorphine (0.4 mg) and slow release morphine sulphate tablets (MST, 20 mg) given 6 hourly in a double-blind, double-dummy trial. Both MST and buprenorphine produced satisfactory postoperative analgesia but the linear analogue pain scores were significantly lower on the second post operative day with MST.

Abdomen↗
PubMed1984

Barrier pressure and muscle relaxants. Comparison of the effects of pancuronium and vecuronium on the lower oesophageal sphincter.

The effects of pancuronium and vecuronium on the lower oesophageal sphincter pressure were studied in 24 healthy patients anaesthetised with 0.5% halothane in nitrous oxide and oxygen. Following pancuronium 0.1 mg/kg intravenously, there was a significant increase in barrier pressure from a control value of 2.0 (SEM 0.14) kPa to 3.0 (SEM 0.27) kPa 1 minute after injection (p less than 0.05). This increase was sustained throughout the 15 minute period of recording and was accompanied by a significant increase in heart rate (p less than 0.001). Following administration of vecuronium 0.1 mg/kg intravenously there was an initial modest, though not significant increase in barrier pressure. This increase was significant (p less than 0.05) at 15 minutes. There were no cardiovascular changes following vecuronium.

Anesthesia, Inhalation↗
PubMed1984

Plasma catecholamine concentrations. The effects of infiltration with local analgesics and vasoconstrictors during nasal operations.

Plasma catecholamine concentrations were measured in 19 patients allocated randomly to receive submucous infiltration with 4 ml of either 0.5% lignocaine with adrenaline 1:200 000 or prilocaine 0.5% with octapressin 0.03 iu per ml. Venous blood samples were obtained before and at 2, 5, and 10 minutes following infiltration. Plasma adrenaline increased from 0.35 to 1.72 p mol/ml at 2 minutes infiltration with the former solution whilst there was little change in plasma noradrenaline concentration. No similar peak in adrenaline concentration occurred after infiltration with prilocaine/ octapressin solutions but with both solutions there was a small increase in plasma noradrenaline and adrenaline concentrations 10 minutes after infiltration, at the time of surgical stimulation.

Adolescent↗
PubMed1984

Effects of ascorbic acid and disodium edetate on the stability of isoprenaline hydrochloride injection.

Disodium edetate (0.01%), either alone or in combination with ascorbic acid (0.1%) was an effective stabilizer for isoprenaline injection B.P. but adjustment to pH 2.8 was necessary. The bubbling of nitrogen through the solution in the ampoule before sealing did not prevent degradation in unprotected solutions. Solutions sterilized by filtration or by autoclaving for 30 min at 116 degrees C were stable for at least 1 year at 5 degrees C or 25 degrees C.

Ascorbic Acid↗
PubMed1984

Intravesical methotrexate in the treatment of superficial bladder cancer.

Thirty patients with superficial bladder cancer (Tis, Ta, Tl) difficult to control by endoscopic means were given a total of 49 courses of methotrexate at fortnightly intervals. Four concentrations were investigated. In 14 courses this was the sole treatment and in the remainder the methotrexate was given as prophylaxis. Toxicity was not a problem but in both groups, although there was some evidence of anti-tumour activity, there were high recurrence rates and intravesical methotrexate cannot be recommended.

Carcinoma, Transitional Cell↗
PubMed1984

Changes in salivary peroxidase activity observed during experimentally-induced gingivitis.

Gingivitis was experimentally induced in 8 human subjects using an acrylic overlay to cover the teeth in the experimental area during any oral hygiene procedures. The overlays were used for a period of 3 weeks, after which the subjects received a scale and polish and then practised normal oral hygiene. At regular intervals during the experimental period, mixed saliva was collected for assay of peroxidase activity by spectrophotometric and test-strip procedures and plaque and gingival indices were assessed clinically. A considerable increase in peroxidase activity was observed during the experimental period, which declined after normal hygiene was resumed. This procedure may allow assessment of the progression of gingivitis under experimental conditions.

Adolescent↗
PubMed1984

Glycosaminoglycans in fluid aspirates from odontogenic cysts.

Glycosaminoglycans and proteoglycans were analysed in keratinizing and nonkeratinizing odontogenic cyst fluids. Hyaluronic acid showed the highest incidence and abundance amongst the glycosaminoglycans detected. Appreciable amounts of chondroitin-4-sulphate were also observed, particularly in the dental cysts, with lesser amounts of the other glycosaminoglycans. Heparan sulphate showed a higher incidence and abundance in the keratocyst than the other cysts, whilst chondroitin-6-sulphate could not be detected in any of the cysts. A considerable proportion of the glycosaminoglycans of the fluids appeared to be complexed with protein and was released only after proteolytic digestion. The origin of these macromolecules is uncertain although it is likely that they are derived from both the connective tissue and the epithelium of the cyst wall.

Ameloblastoma↗
PubMed1984

Effects of feeding lupin seed naturally infected with Phomopsis leptostromiformis to sheep and pigs.

Lupin seed, 10% of which was naturally infected with Phomopsis leptostromiformis was obtained from 2 different sources and stored either conventionally, or in a warm and humid environment, for 45 weeks. Only very low levels of toxicity were apparent during the storage period and in the warm, humid environment the level of infection of P. leptostromiformis was gradually reduced and eventually eliminated. The 2 batches of infected seed, and non-infected lupin seed, were fed to sheep as sole rations for 40 weeks, or as part of feedlot rations for 10 weeks, and to baconer pigs as part of grower and finisher rations for 16 weeks. In the 40-week feeding trial mild lupinosis developed in sheep fed from one batch of infected seed, but there was no evidence of lupinosis in sheep fed the feedlot rations, or pigs fed the grower and finisher rations. It is suggested that lupin seed with levels of Phomopsis-infection of up to 10% could be safely fed to sheep and pigs under commercial conditions.

Animal Feed↗
PubMed1984

Capacity of a cis-diammineplatinum[II]-polyglutamic acid complex to cure Trypanosoma congolense infections in mice.

A cis-diammineplatinum(II)-polyglutamic acid complex proved to have marked trypanocidal activity in vivo. When 5 mg of platinum per kg was administered daily for 5 days or when 20 mg of platinum per kg was administered on days 1, 3, and 6, five of five treated Trypanosoma congolense-infected mice were cured. In contrast, cis-platin was ineffective at all doses tested. We believe that the complex has a much higher therapeutic ratio than does uncomplexed drug because it is less toxic.

Animals↗