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Biomedical subjects

P J Boyd

Publications and source records attributed to P J Boyd.

14 recordsLinked to original sources
PubMed1991

Application of phase-induced lateralization to the Stenger test.

The Stenger test was employed to estimate the genuine hearing thresholds in normally hearing volunteer subjects simulating a total unilateral loss. The test was carried out in its standard form and in a modified form in which a phase shift was introduced between the signal delivered to the two ears, set to produce phase-induced lateralization towards the 'poor' ear. The standard test estimated the thresholds at a mean of 13.5 dB above the true thresholds at five frequencies from 250 Hz to 4 kHz. Thresholds at the different frequencies were compared, and although thresholds were lower for the higher frequencies, the apparent effect of frequency was not statistically significant. The modified test, using a 90 degrees phase shift, was found to enhance the test at 250 and 500 Hz (thresholds estimated at about 7 dB above true values), but not significantly at 1 kHz.

Adult↗
PubMed1987

Localization of ARG-vasopressin-like material in central neurones and mechanism of action of ARG-vasotocin on identified neurones of the snail Helix aspersa.

Immunocytochemical and electrophysiological studies were made on neurones in the suboesophageal ganglia of Helix aspersa. A group of neurones in the anterior dorsal surface of each parietal ganglion showed positive immunoreactivity to an antibody to arginine vasopressin (AVP), as did the neuropile and the nerves associated with the parietal and visceral ganglia. The only peripheral tissue to exhibit positive immunoreactivity to AVP was the optic tentacle, where positive immunoreactive fibres were present in the optic nerve and cell bodies below the retinal cell layer. Two central neurones, F1 and E13 were excited by arginine vasotocin (AVT), threshold 1-10 nM, and the ionic mechanism associated with this response was investigated. This excitation involved both sodium and calcium ions with an overall increase in resistance. In low sodium Ringer, the AVT response was greatly reduced, while in calcium-free 3 mM cobalt Ringer, the response was potentiated. Changing the external concentrations of potassium and chloride ions had no apparent effect on the response. The amplitude of the excitation induced by AVT was enhanced when the cells were hyperpolarized. Most of the other neurones tested failed to respond to AVT though the excitatory response of certain cells to acetylcholine was enhanced by 0.1 microM AVT. Excitation by 5-hydroxytryptamine was unaffected in the cells tested. This study provides further evidence for a role for an AVT-like peptide in the nervous system of Helix.

Acetylcholine↗
PubMed1987

Comparison of the effects of FMRF-amide and pQDPFLRF-amide on identified Helix neurons.

Intracellular recordings were made from a selection of identified neurons in the sub-oesophageal ganglia of Helix aspersa, and their responses to the molluscan neuropeptides FMRF-amide and pQDPFLRF-amide compared. While FMRF-amide excited certain neurons and inhibited others, pQDPFLRF-amide did not produce excitation in any of the cells tested. A few cells were unresponsive to pQDPFLRF-amide, but most were inhibited with varying potency. FMRF-amide was generally 10-100 times more potent than pQDPFLRF-amide, but one cell, E13 in the visceral ganglion, showed equal sensitivity to the two peptides. On most cells there was no clear evidence for cross desensitization between the two peptides, although it is possible that in some cases where both peptides are inhibitory they may be acting on a single receptor.

Action Potentials↗
PubMed1986

Substance P-like immunoreactivity in the retina and optic lobe of the squid.

The distribution of substance P-like immunoreactivity within the squid retina and brain was studied by immunofluorescence. Positive immunoreactivity was observed as a single layer of fibres in the retina. The retina was devoid of tyrosine-hydroxylase, serotonin, gamma-aminobutyric acid, cholecystokinin, neuropeptide Y, somatostatin, enkephalin and vasoactive intestinal peptide immunoreactivities. Substance P immunoreactivity was particularly abundant in the optic lobe. The optic lobe had a distinct layer of substance P fibres near the periphery. Immunoreactive cell bodies, fibres and varicosities were additionally present in various areas of the optic lobe. Substance P immunoreactivity in the other ganglia of the brain was restricted to a few scattered fibres.

Animals↗
PubMed1986

Localization of a substance P-like material in the central and peripheral nervous system of the snail Helix aspersa.

A monoclonal antibody against substance P was used for immunocytochemical staining of the central ganglia of the snail Helix aspersa and several peripheral tissues including the gut, reproductive system, cardiovascular system, tentacle and other muscles. Within the central ganglia many neurons, and many fibres in the neuropile and the nerves entering the ganglia, were stained for the SP-like material. The largest numbers of reactive cell bodies were in the pleural ganglia and on the dorsal surfaces of the pedal ganglia. A group of cells was also found, surrounding the right pedal-cerebral connective, that did not fluoresce, but were enveloped by reactive processes terminating directly onto the neurone somata. Specific staining was observed in all peripheral tissues examined and always appeared to be concentrated in nerve terminals. Most particularly these occurred in the heart and aorta, the pharyngeal retractor muscle and the tentacle. Although mostly present in muscular tissues, some fluorescence was also observed in the nervous layer surrounding the retina. The tentacular ganglion also contained immunoreactive cell bodies.

Animals↗
PubMed1985

Actions of the molluscan neuropeptide FMRF-amide on neurones in the suboesophageal ganglia of the snail Helix aspersa.

The effects of the molluscan neuropeptide FMRF-amide were tested on several neurones in the suboesophageal ganglia of the snail Helix aspersa. Almost all neurones tested responded to the peptide, some being hyperpolarized (H response) and others depolarized (D response). The H response is due primarily to an inward potassium current and may be blocked in 20 microM 4-aminopyridine. The hyperpolarizing actions of FMRF-amide and dopamine may be separated by ergometrine which blocks the response to dopamine but not to FMRF-amide. The D response is due mainly to an inward sodium current but this is not blocked by d-tubocurarine, morphine or TTX. It appears to be mediated by a distinct receptor/ionophore as excitation by ACh and 5-HT are both antagonized by d-tubocurarine. The Leu2-substituted analogue FLRF-amide was found to produce similar H responses to FMRF-amide, but was much less potent at producing D responses. It did, however, produce cross-desensitization of the D response to FMRF-amide, suggesting that it does bind to the FMRF-amide receptor.

Animals↗
PubMed1978

CT scanning and the surgery of metastatic teratoma of the testis: a preliminary report.

Accurate definition of metastases in para-aortic lymph nodes and lungs is essential in planning treatment for patients with testicular teratoma. The addition of CT scanning to routine investigation of these patients has given additional sensitivity in detection and localisation of metastases. The extent of para-aortic metastases could be clearly defined, even when bulk replacement of nodes prevented definition by lymphography. This information was used in planning the best surgical approach for para-aortic lymphadenectomy, which was done as part of combined treatment of large volume metastases.

Humans↗
PubMed1977

Haematuria.

Explore the source record for details and available documents.

Cystoscopy↗
PubMed1977

Survival in 200 patients treated by haemodialysis and renal transplantation.

The survival rates in 200 patients with terminal renal failure treated by maintenance haemodialysis and renal transplantation were analysed. The overall survival rate (+/- SE) was 81-4 +/- 3% at two years, 68-4 +/- 4% at five years, and 60-8 +/- 4-8% at eight years. Survival was inversely related to age: in those aged 15-34 years overall survival was 89-7 +/- 3-7% at two years, 87-8 +/- 4-1% at five years, and 83-9 +/- 5-5% at eight years. Eighty per cent of the surviving patients were able to work full time. The survival rate in patients returned to dialysis after graft rejection was 87-5% +/- 8-3 at three years.

Adolescent↗
PubMed1976

Single dose intravesical thiotepa as an adjuvant to cystodiathermy in the treatment of transitional cell bladder carcinoma.

Tumour cell implantation may be a factor in the aetiology of recurrent well-differentiated superficial bladder tumours. A prospective trial is reported in which single dose intravesical thiotepa was administered to a group of randomly selected patients immediately after cystodiathermy. A control group of patients was treated by cystodiathermy alone and tumour recurrence in the 2 groups was compared. Significantly fewer patients in the thiotepa-treated group developed recurrent tumour and there was also a significantly reduced incidence of pure vault recurrence in this group. The beneficial effects of adjuvant thiotepa were apparent after 1 treatment. In this series of patients no benefit resulted from the continued use of adjuvant thiotepa once a patient developed a recurrent tumor.

Carcinoma, Transitional Cell↗
PubMed1975

Staphylococcus aureus transmitted in transplanted kidneys.

Staphylococcus aureus septicaemia developed shortly after transplantation in both recipients of transplanted kidneys from a donor who had received electrical burns. In each case the organism appeared initially in the urine. All staphylococci isolated were phage type 6/47/54/75. Transplant nephrectomy was necessary in both recipients because of complications of infection, and one recipient died. These results draw attention to the possible significance of Staph. aureus in the urine of recipients after transplantation and to the potential risk of transplanting kidneys from a burned donor.

Adult↗
PubMed1975

Automated assay of N-acetyl-beta-glucosaminidase in normal and pathological human urine.

An automated method for the assay of N-acetyl-beta-glucosaminidase in human urine is described and a normal range of urinary N-acetyl-beta-glucosaminidase activity is reported. The automated method has been used routinely over a twelve month period in two London hospitals for monitoring the excretion of N-acetyl-beta-glucosaminidase in renal transplant patients. The abnormal elevation of urinary N-acetyl-beta-glucosaminidase provides an early warning of rejection by indicating the presence of renal parenchymal damage. The automated assay of urinary N-acetyl-beta-glucosaminidase may also be used in screening for the presence of renal disease.

Acetylglucosaminidase↗