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Biomedical subjects

M H Bennett

Publications and source records attributed to M H Bennett.

At least 73 records · Page 4Linked to original sources
PubMed1984

Immunocytochemical localization of neuron specific enolase in small cell carcinomas and carcinoid tumours of the lung.

Carcinoid tumours and small cell carcinomas of the lung share many characteristics with normal neuroendocrine cells. While carcinoid tumours contain many dense-cored neurosecretory granules and are frequently argyrophil, small cell carcinomas are poorly granulated and rarely argyrophil, which casts doubt on their neuroendocrine nature. Immunostaining of the enzyme neuron specific enolase (NSE) was recently used to demonstrate the neuroendocrine components of the lung including nerves and neuroendocrine cells. We therefore used NSE immunostaining to investigate neuroendocrine differentiation in 79 lung tumours, including 18 bronchial carcinoids and 31 small cell carcinomas, and compared these results with those obtained with silver stains. Thirteen of the 18 carcinoids were reactive to silver, all other types being negative. NSE-immunoreactivity occurred in 16 carcinoids and 18 small cell carcinomas. None of the squamous cell carcinomas, large cell anaplastic carcinomas and adenocarcinomas examined showed NSE-immunoreactivity. Radioimmunoassay of extractable NSE from 10 fresh lung tumours correlated well with the immunostaining results, demonstrating large amounts in two small cell carcinomas (334 and 517 ng/mg protein) and three carcinoids (152, 908, and 1143 ng/mg protein). Values were much lower for four squamous cell carcinomas (31-44 ng/mg protein) and one large cell anaplastic carcinoma (30 ng/mg protein) and were accounted for by the presence of NSE-positive nerves and neuroendocrine cells in the surrounding lung. NSE immunostaining is a useful marker of neuroendocrine differentiation in lung tumours and should prove particularly valuable in the diagnosis of small cell anaplastic tumours and their metastases.

Carcinoid Tumor↗
PubMed1984

Percutaneous retrogasserian glycerol rhizotomy for tic douloureux: Part 1. Technique and results in 112 patients.

The technique and results of treatment of tic douloureux by percutaneous retrogasserian glycerol rhizotomy ( PRGR ) were assessed in a series of 112 patients. All patients were refractory to or intolerant of medical therapy. Many of these patients had recurrent pain despite such surgical treatment as microvascular decompression (21%) or one or more percutaneous radiofrequency thermal rhizotomies (19%). The follow-up duration after glycerol rhizotomy ranged from 4 to 28 months. At the final assessment, 67% had complete pain relief; 23% were improved, with pan relieved by minimal drug therapy; and 10% had poor results with unsatisfactory pain relief even with medications. Before the final assessment, 19 patients required a second PRGR because of an initially suboptimal injection (10%) or recurrent pain (16.9%). Seventy-three per cent had no demonstrable change in facial sensation after operation. H akanson 's original procedure based on anatomic verification by cisternography provided precise localization, required no intraoperative stimulation or lesion generators, and allowed varied anesthetic options during operation. In contrast to thermal rhizotomy, PRGR offers patients relief of painful tic douloureux without altering facial sensation in most cases.

Adult↗
PubMed1984

Percutaneous retrogasserian glycerol rhizotomy for tic douloureux: Part 2. Results nd implications of trigeminal evoked potential studies.

Trigeminal evoked potentials were recorded before and 6 weeks after a percutaneous retrogasserian glycerol rhizotomy was performed in 22 patients with tic douloureux. The latency of the trigeminal evoked potential (TEP) N20 peak and the sensory threshold to electrical stimulation of the maxillary gum were measured in each patient. The N20 latency differences between normal and affected sides for each patient were reduced after glycerol injection. Sensory thresholds were significantly different between the normal and the affected sides both before and after rhizotomy. These results were interpreted to indicate that glycerol more specifically affects the damaged myelinated axons implicated in the pathogenesis of trigeminal neuralgia. Of the 22 patients, 82% were either pain-free or significantly improved after operation. Postoperative normal N20 latencies were associated with pain relief in most cases. Our preliminary experience suggests that recurrent pain is more likely to develop in those patients whose postoperative TEP remains abnormal, especially if the abnormality cannot be ascribed to a prior surgical deafferentiation procedure. In addition to providing insight into the mechanism of pain relief, TEP measurements may help to predict the likelihood of long term relief after percutaneous retrogasserian glycerol rhizotomy.

Electrophysiology↗
PubMed1983

Effects of compression and ischemia on spinal cord evoked potentials.

Ascending and descending spinal cord potentials were recorded during conduction block produced by compression and ischemia to the spinal cord of cats. Dorsally and ventrally applied compression produced proportional changes in both ascending and descending potentials. Results for induced ischemia were much more variable. Although both systems were significantly affected by extreme ischemia, loss of descending activity was not always accompanied by a loss of ascending activity for lesser ischemic insults. This finding was attributed to the variability of the spinal cord vascular supply. It is concluded that monitoring of ascending evoked activity (e.g., somatosensory evoked potentials) would reflect changes in descending spinal cord conduction for compressive and higher magnitude ischemic spinal cord insult. It is also pointed out that lesser degrees of spinal cord ischemia can produce dysfunction in descending systems which may not be detected by monitoring of somatosensory evoked potentials. The significance of the observed relationship between ascending spinal cord and cortical evoked potentials is also discussed.

Animals↗
PubMed1983

The prognostic significance of cellular subtypes in nodular sclerosing Hodgkin's disease: an analysis of 271 non-laparotomised cases (BNLI report no. 22).

A histological review of 271 cases of nodular sclerosing Hodgkin's disease, patients presenting with clinical Stage I, II and III disease but not subjected to a staging laparotomy, has been undertaken. Cases were categorised according to the cytological appearances of the cellular nodules and the degree of sclerosis was examined. Cytological subtypes with extensive and easily recognised areas of lymphocyte depletion or numerous pleomorphic Hodgkin's cells were associated with a decreased survival and clinical stage did not appear to be a good indicator of prognosis in these patients. Pronounced nodal sclerosis was associated with a higher relative frequency of mediastinal disease and the lymphocyte-depleted cytological subtypes.

Actuarial Analysis↗
PubMed1983

Evoked potentials in trigeminal neuralgia.

Trigeminal evoked potentials and sensory thresholds in response to maxillary gum stimulation were obtained in patients with a complaint of unilateral face pain. The patients and the volunteer, normal control groups had undergone no prior surgical or other procedures involving cranial or cervical structures. For statistical purposes, patient data were analyzed with respect to the diagnostic classification of classical trigeminal neuralgia, atypical trigeminal neuralgia, or other face pain states in which the pain extended beyond the trigeminal nerve distribution. Latencies of trigeminal evoked potentials on the affected side were significantly increased (compared to normal control group responses) in patients with classical but not in those with atypical trigeminal neuralgia nor other face pain syndromes. All three patient groups had statistically significant threshold elevations on the affected side compared to the unaffected side. A high level of significance for this test was obtained for the classical trigeminal neuralgia group. Ratings for patients based upon the preoperative electrophysiological findings were highly correlated with long term results of microvascular decompression of the 5th nerve root for classical, but not for atypical trigeminal neuralgia patients. These results support the view that atypical and classical trigeminal neuralgia symptom complexes are caused by different types of physiological dysfunction and that classical trigeminal neuralgia is associated with compression of the trigeminal nerve root. It was suggested that the rating system may be a useful, objective, clinical adjunct in evaluating patients with classical trigeminal neuralgia.

Afferent Pathways↗
PubMed1982

Interstitial radiation therapeutic techniques at Mount Vernon Hospital.

Retrospective analysis of 56 cases of carcinoma on the lateral border of the anterior two thirds of the tongue treated at Mount Vernon Hospital using radium needle implant alone yielded 5-year actuarial survivals of 75.3 per cent in 25 T1N0 cases and 81.8 per cent in 25 T2N0 cases. Five-year actuarial local recurrence of 17.5 per cent was recorded in the T1 group and 35 per cent in the T2 group. Local recurrences were attributed to failure of the implant to encompass extensions of the tumour along the lateral border or into the musculature of the tongue. Five-year actuarial local recurrence of 66.2 per cent was recorded in 18 patients with carcinoma of the breast treated by radium needle implant alone; 4 of these 9 local recurrences occurred at some distance from the treated area and could not be classed as marginal recurrences. A preliminary investigation carried out in 1981 indicated that significant improvements in source distribution, particularly at poorly accessible sites, could be achieved using afterloading techniques. In addition the use of 192Ir as a source could result in improvements in staff protection.

Adult↗
PubMed1981

Feedback controlled nerve fiber impalement.

A device has been described for the automatic impalement of nerve fibers. Although developed specifically for that task, the technique can be applied for intracellular recording from other cells or processes. The basis of the techniques is to use the cell membrane potential to stop the advance of a fast moving microelectrode. With slight modification it can be used to stop microdrive advance upon receipt of an action potential. The circuit was constructed by interconnecting commercially available instruments found in most electrophysiology laboratories. Use of the device for recording from the dorsal column fibers of the cat increased the number of stable cell penetrations per unit of time by between one and two orders of magnitude.

Animals↗
PubMed1981

The concentration of desmethylmisonidazole in human tumours and in cerebrospinal fluid.

The concentration of desmethylmisonidazole (DESMISO) was determined in 60 biopsy samples taken from 13 human tumours and in cerebrospinal fluid (CSF) from 8 patients after oral administration. In comparison with misonidazole (MISO), peak concentrations in plasma were reached at earlier times and half-lives were shorter, so that the area under the curve of plasma concentration with time (AUC) was reduced by 45%; the AUC of CSF concentration with time was reduced by 67%. Between 1 and 2 h after administration of DESMISO, concentrations in tumours were generally 85-90% of those of MISO estimated approximately 4 h after it was given. The two drugs when tested in equimolar concentrations have been found in laboratory experiment to be equally potent as hypoxic cell radiosensitizers. Recognizing the lower mol. wt of DESMISO and the trend to higher concentrations in the more necrotic areas of the tumours studied equal doses by weight of the two drugs given orally may give equal radiosensitization of hypoxic cells in human tumours.

Breast Neoplasms↗
PubMed1981

Fibroblast adhesion on collagen substrata in the presence and absence of plasma fibronectin.

We have used scanning electron microscopy and transmission electron microscopy to compare the initial adhesion of baby hamster kidney (BHK) cells and early passage human skin fibroblasts on glass, dried collagen, and hydrated collagen substrata. On glass or dried collagen substrata, BHK cell spreading required fibronectin and the cells were extensively flattened, with broad lamellipodia. In marked contrast, BHK cell spreading on hydrated collagen substrata did not require fibronectin and the cell bodies tended to be rounded, with one or several large filipodia. These filipodia generally penetrated into collagen lattice where they interwove with the collagen fibrils. Proteolysis of the collagen was not evident. In the presence of fibronectin, the morphology of BHK cell spreading on hydrated collagen substrata was similar, except that there was an increase in the number of cells that spread with lamellipodia that did not penetrate the collagen lattice. Human fibroblasts also demonstrated marked differences in cell spreading on glass or dried collagen compared to hydrated collagen substrata. Spreading was characterized by lamellipodia on glass or dried collagen but by multiple filipodia on hydrated collagen. In the latter case, the filipodia penetrated just beneath the surface of the collagen lattice. Added fibronectin was not required for spreading on human fibroblasts on any of the substrata and the presence of added fibronectin had no effect on cell morphology. Finally, the human fibroblasts were observed to form adhesion plaques in some cases where the fibroblasts made close contacts with individual collagen fibrils. The results are discussed in terms of connective tissue organization.

Animals↗
PubMed1980

Trigeminal evoked potentials in humans.

Techniques were described for recording trigeminal evoked potentials in humans in response to maxillary gum stimulation. Variations in the responses as a function of stimulating and recording electrode position and stimulus intensity were presented. A standard methodology was proposed in order to obtain the characteristic response repeatedly. The characteristic triphasic wave form consisted, primarily, of an N20, P34, N51 sequence of deflections. Average latencies of components were derived from recordings following stimulation of the asymptomatic side of the face in a patient population. Indirect tests supported the view that muscle potentials did not significantly contribute to the characteristic response. It was concluded that the techniques were suitable for electrophysiological testing of fifth nerve function in routine clinical applications.

Bicuspid↗
PubMed1980

Tumour regression as a guide to prognosis: a clinical study.

The response seen at the end of a course of radiotherapy in 116 patients with advanced carcinoma of the cervix included in hyperbaric oxygen trials was assessed by reduction in bulk and by histological examination. These patients have now been carefully followed for a minimum of three and a maximum of 13 years. The degree of regression, three and a maximum of 13 years. The degree of regression, as measured by reduction in bulk at the primary site, was as measured by reduction in bulk at the primary site, was found to predict closely the subsequent local tumour failure, survival and freedom from metastasis. The histological assessment also could be associated with the subsequent course, but the correlation was much weaker. In a trial of hyperbaric oxygen, where radiotherapy was given in 27 fractions to both groups, the immediate response was significantly better in the patients treated in oxygen, so predicting the result of the trial seen in long-term follow up. In the radiotherapy of carcinoma of cervix, reduction in bulk of the primary tumour at the end of treatment is a valuable prognostic index.

Female↗