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Biomedical subjects

P Whitfield

Publications and source records attributed to P Whitfield.

16 recordsLinked to original sources
PubMed2006

Anatomical and surgical considerations of the external branch of the superior laryngeal nerve: a systematic review.

The anatomical course of the external branch of the superior laryngeal nerve (EBSLN) is variable, and a consistent approach to its preservation during thyroid surgery is needed to reduce risk of post-operative voice impairment. Despite agreement that careful dissection in the region of the superior thyroid pole is required, there is no accepted 'best' approach, nor any universal acknowledgement that location of the EBSLN is actually necessary. The popular cernea classification of EBSLN has limitations, including its decreased reliability with increased thyroid size and its irrelevance in cases of 'buried' variants. * Recent work has identified factors such as ethnicity and stature in the prevalence of EBSLN variants. Consistent approaches to the post-operative detection of EBSLN injury are needed to build an accurate picture of the incidence of surgical nerve injury. Then a standardised approach to EBSLN preservation may emerge.

Clinical Trials as Topic↗
PubMed2000

GM1-gangliosidosis in a cross-bred dog confirmed by detection of GM1-ganglioside using electrospray ionisation-tandem mass spectrometry.

The post-mortem diagnosis of lysosomal storage diseases can be confounded by the unavailability of suitable material. Here we report the diagnosis of GM1-gangliosidosis in a cross-bred dog, from which only formalin-fixed brain was available, by a combination of electron microscopy and the detection of elevated levels of GM1-ganglioside within the tissue using the novel technique of electrospray ionisation tandem mass spectrometry. Electron microscopic examination of ultrathin sections of resin-embedded tissue revealed cytoplasmic inclusions (membranous cytoplasmic and zebra bodies) in brain stem and cerebellar neurons that were characteristic of a gangliosidosis. Glycolipids were extracted from the fixed tissue and analysed by tandem mass spectrometry. Two major ions were detected, which corresponded to GM1 (d18:1-C18:0) and Gm1 (d20:1-C18:0). Their identity was confirmed by comparison of their fragmentation patterns with those of authentic standards. The concentration of GM1 was approximately sixfold higher on a wet weight basis than in the brain of a normal control dog, confirming the diagnosis of GM1-gangliosidosis.

Animals↗
PubMed1998

The role of phytosterols in the pathogenesis of liver complications of pediatric parenteral nutrition.

Long-term parenteral nutrition of infants who have had major gut resections is associated with a high incidence of cholestatic liver disease. Affected infants have high plasma concentrations of phytosterols--compounds that resemble cholesterol but have an alkylated side chain. The phytosterols that accumulate in patients receiving parenteral nutrition are derived from the soya oil and/or soya lecithin used to make the intravenous lipid emulsion. There is a striking association between phytosterolemia and cholestatic liver disease. This has led us to put forward the hypothesis that phytosterols can cause cholestasis in susceptible infants. Experiments using neonatal piglets indicate that phytosterols (given without any of the other components of parenteral nutrition) can indeed reduce bile flow. We suggest that increasing the content of phytosterols in cell membranes may interfere with the function of important transport proteins involved in the secretion of bile. Other factors that might contribute to cholestasis (such as inhibition of cholesterol 7 alpha-hydroxylase) are discussed.

Bile↗
PubMed1991

Host-parasite interface of the urinary bladder-inhabiting nematode Trichosomoides crassicauda: changes induced in the urothelium of infected rats.

The urinary bladders of rats infected with Trichosomoides crassicauda were studied by light, scanning and transmission electron microscopy. The bladder epithelium of infected rats showed a diffuse, mild, flat hyperplasia, four to six cells thick. The anterior parts of adult female worms were embedded in tunnels within the hyperplastic epithelium with the posterior portions of the parasites lying free in the bladder lumen. The hyperplastic epithelial cells forming the inner layer of the tunnel wall, adjacent to the parasite, showed degenerative changes. These cells contained single or multiple pycnotic nuclei. Their cytoplasm was fibro-granular in appearance, with few distinct organelles, and the luminal surfaces of the cells were not limited by plasma membranes. Small numbers of granular cells, similar in appearance to mast cells, were seen in, and possibly crossing, the epithelium. There was no infection-related increase in the number or type of inflammatory cells in the lamina propria. Questions of interest emerging from this study relate to the nutrition of an adult nematode occupying an intra-epithelial location, and the absence of a significant chronic inflammatory response to the mature worm. It is suggested that the avascular hyperplastic epithelium of the bladder is an immunologically 'protected site' for the mature female T. crassicauda.

Animals↗
PubMed1990

Motivational factors in women requesting augmentation and reduction mammaplasty.

This study confirms that women requesting breast reduction and breast augmentation differ beyond the anatomical. There were significantly more single and co-habiting women in the breast reduction group, and significantly more separated and divorced women in the breast augmentation group, compared to women attending an obstetric clinic. The majority of women requesting surgery agreed that to feel more confident was an important reason for seeking surgery, but those requesting breast augmentation also stressed the need to feel more feminine and less shy with men. A significantly higher percentage of the breast augmentation group had been pregnant, and they had a higher average number of pregnancies than the obstetric comparison group, together with a significantly higher experience of miscarriage. The psychodynamic proposal that women requesting breast augmentation are seeking to symbolically boost their sense of femininity and womanliness is supported by this study.

Adaptation, Psychological↗
PubMed1985

Comparison of weight, depth, and diagnostic adequacy of specimens obtained with 16 different biopsy forceps designed for upper gastrointestinal endoscopy.

The influence of endoscopic forceps variables (size, design, and make) on biopsy specimen weight, depth, and diagnostic adequacy has been studied in vitro on normal human stomach, and in vivo at endoscopy in dog and in patients. Greater pressure during the biopsy procedure yielded significantly heavier, deeper, and histologically more acceptable specimens. Standard sized forceps (diameter 2.4 mm) and those with ellipsoid cups consistently produced larger specimens than the smaller 'paediatric' forceps (1.8 mm) and those with round cups. Deeper specimens were also obtained using the standard forceps. In vitro and in vivo in the dog, the standard sized forceps also produced specimens of greater diagnostic adequacy than the paediatric forceps. At endoscopy in patients, however, we could not detect any influence of the size, shape, and presence of forceps spike or fenestration on the diagnostic adequacy of the specimens.

Animals↗
PubMed1978

The significance of urinary melanoma antigen excretion and the ability of thymosin to raise the level of depleted lymphocytes in vitro in malignant melanoma.

One hundred and fifty-six patients were screened for the presence of urinary melanoma antigen and serum cytoplasmic antibody. It was found that 44% of symptomless Stage 1 patients tested five to 15 years after operation had detectable antigen (Ag) in their urine; the urines of 67% of Stage 2A (local recurrence) patients were positive for Ag; while in only 38% of those patients graded 2B (lymph-node involvement) were these tests positive. Urines of 83% of patients with generalized metastases (Stage 3) were positive. A sequential study was made of 23 patients seen and treated in 1976. Of this group, 14 reverted from a positive state to a negative one following excision of their tumour, while six were negative on first postoperative testing and subsequently became positive. Three out of the 23 remained persistently negative. T lymphocyte levels were assessed in 71 melanoma patients, and a stage-related fall was noticed. Thymosin (Hoffman LaRoche) on in vitro incubation significantly raised the levels of T lymphocytes.

Adult↗
PubMed1975

The predictive accuracy of the postvagotomy insulin test: A new interpretation.

Insulin-stimulated gastric secretion alone, without reference to basal secretion, has been examined in 45 male patients with duodenal ulcer in whom no gastric operation had been performed and in 124 patients following vagotomy for duodenal ulcer. Gastric juice was examined in terms not only of conventional indices, observed volume, titratable acidity and acid output, but also Vg, the volume corrected for pyloric loss and duodenal reflux. The range of secretion of the unoperated subjects was established in terms of peak and half-totwo-hour values for all indices. By reference to these ranges, secretion of postvagotomy subjects could be divided into two groups: (a) those with secretion within the preperative range, and (b) those with secretion less than the lower limit of the preoperative range. The best discrimination was given by Vg; those within the preoperative range (peak Vg in excess of 140 ml/hour and Vg half to two hours in excess of 105 ml/hour) had a 50% liability to recurrent ulcer, while those below the preoperative range had a zero liability to recurrent ulcer. Of the conventional indices acid output gave the best discrimination, which was almost as good as Vg. Peak acid output of 8 mmol/hour or acid output one half to two hours of 525 mmol/hour discriminated into two groups, with a 50% or zero liability to recurrent ulcer. Titratable acidity (Hollander's index of secretion), being highly susceptible to reflux, was not an adequate discriminant.

Chlorides↗
PubMed1974

Duodenal reflux during insulin-stimulated secretion.

Insulin-stimulated secretion has been studied in 67 subjects with intact vagi. The relationship between the changes in the concentrations of hydrogen and sodium ions in individual 10-minute samples showed a highly significant negative correlation. In quantitative terms, this correlation could be explained by the mixing of isotonic gastric juice and duodenal reflux but not by back-diffusion. In 37 subjects duodenal juice was labelled with either bromsulphalein (BSP) or indocyanine green (ICG), both dyes being excreted only in the bile. In aspirated gastric juice there were highly significant positive correlations between the concentration of the dye and the concentration of duodenal reflux calculated from a formula based on the output of sodium ions. The volume of duodenal reflux occurring during insulin-stimulated secretion was estimated from the sodium output in normal controls, in preoperative patients with duodenal ulcer, and in patients following vagotomy with or without a drainage procedure. Reflux following gastrojejunostomy greatly exceeded that occurring in all other groups. Reflux following vagotomy with no drainage procedure was less than that in preoperative patients, and in patients in whom pyloroplasty or gastrojejunostomy had been performed.

Duodenal Diseases↗