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Biomedical subjects

G Randall

Publications and source records attributed to G Randall.

12 recordsLinked to original sources
PubMed1992

Distribution of dysplasias and early invasive carcinoma in Barrett's esophagus.

To assess the anatomic relationships between areas of dysplasia and "early" carcinoma, we evaluated histologically the entire mucosal surfaces of seven esophagectomy specimens resected for high-grade dysplasia or early invasive (intramucosal and submucosal) carcinoma. We developed surface area maps and assessed the various degrees of dysplasia or carcinoma at 10 equidistant points. Our analysis shows an equal likelihood of high-grade dysplasia and/or early invasive carcinoma occurring throughout the length of Barrett's epithelium. Foci of carcinoma appear within fields of Barrett's epithelium and adjacent to areas of dysplasia, supporting a dysplasia-carcinoma sequence. The amount of dysplastic epithelium appears related to the surface area of Barrett's epithelium present. However, we found no association between the extent of dysplasia and the likelihood of finding carcinoma. This study supports the current standard of practice for clinical surveillance of patients with Barrett's esophagus by uniformly distributed endoscopic biopsy of the complete length. In addition, the presence of any degree of dysplasia may be an indication for close clinical follow-up.

Aged↗
PubMed1992

In vivo growth hormone (GH) response to human GH-releasing factor (GRF) or somatostatin (SRIF) in foetal pigs.

The short-term effect of hypothalamic GRF and SRIF on the pituitary release of GH at different stages of gestation has been studied. In the present experiment eighteen gilts were used, six at each of 66, 88 and 110 days of gestation. Ventral laparotomy was performed under general anaesthesia and a section of uterus was exteriorized. Blood samples were obtained from the umbilical vein of three foetuses per gilt just prior to the injection of each foetus with either saline, 5 micrograms/kg of hGRF (1-44)NH2 or 50 micrograms/kg of SRIF into the umbilical vein. Additional blood samples were obtained 15, 30, 45 and 60 min post-injection. Serum samples were radioimmuno-assayed for GH (porcine). There was a treatment by gestational age interaction (P less than 0.01) on mean GH concentrations, area under the GH curve and GH peaks. While treatments had no effect (P greater than 0.1) on GH variables at 66 days of gestation, the area under the GH curve was slightly increased by GRF (P = 0.14) at day 88 and all GH variables were significantly increased (P less than 0.01)) by GRF at 110 days of gestation. There was a quadratic effect of time post-injection on GH concentrations at 88 (P less than 0.05) and 110 (P less than 0.001) days of gestation. There was no effect of SRIF injection (P greater than 0.1) on GH concentrations at any gestational age. In conclusion, the foetal pituitary responsiveness to GRF develops with foetal age and is maximal at the end of gestation, whereas there is no short-term response to a bolus of SRIF at any stage of gestation.

Animals↗
PubMed1989

The effects of the anti-tumor agent mezerein on the cytotoxic capacity and oxidative metabolism of human blood cells.

Mezerein, the most active antitumor compound isolated from the daphne species of plants, has a structural similarity to phorbol myristate acetate (PMA), the major active compound isolated from croton oil. PMA is known to have tumor promoting activity and is a potent inflammatory agent. Mezerein has similarly been reported to have potent inflammatory properties but appears to be a weaker tumor promoter than PMA. While the effect of PMA on the function and metabolism of human blood cells has been extensively studied, there is little similar information concerning mezerein. Therefore, in these studies, we have compared the capacities of mezerein and PMA to activate the cytotoxic capacity and oxidative metabolism of human granulocyte (PMNs), monocyte, lymphocyte, and mononuclear cell (lymphocytes and monocytes) cultures in vitro. Mezerein stimulated the oxidative metabolism of PMNs in an identical manner to PMA as indicated by a burst in the activity of the HMPS pathway, the production of H2O2, hydroxyl radical and stable oxidants. Mezerein also stimulated the release of thromboxane B2 from PMNs. Both compounds activated the oxidative metabolism of monocytes but not the oxidative metabolism of lymphocytes. The enhanced oxidative metabolism of the phagocytic cells was associated with an increased cytotoxicity against human red cells which are sensitive to oxidant damage but not against the NK resistant Raji lymphoblast cell line or the SW1116 colon tumor cell line. Of interest is that mezerein did not augment significantly the minimal cytotoxic capacity (NK activity) of mononuclear cells, monocytes or freshly isolated lymphocyte cultures against the tumor cell targets used in our experiments. However, lymphocyte cultures preincubated for 15 hours with mezerein had a marked enhancement of cytotoxicity against the tumor targets. This activation was not observed in similarly treated mononuclear cell cultures suggesting a suppressor activity of the monocytes. Our data suggest that the potent inflammatory activity of mezerein similar to PMA, may be related to its capacity to activate the oxidative and arachidonic metabolism of phagocytic cells. In addition, the capacity of mezerein to activate the cytotoxic capacity of lymphocytes may relate to its reported in vivo antitumor activity.

Antineoplastic Agents, Phytogenic↗
PubMed1988

Comparison of low-power YAG laser and BICAP tumor probe for palliation of esophageal cancer strictures.

The purposes of this study were (a) to determine the applicability of endoscopic palliation for patients with esophagogastric cancer strictures in a referral center, and (b) to compare the efficacy and safety of the BICAP tumor probe with the neodymiumyttrium-aluminum-garnet (YAG) laser for such palliation. Forty-two consecutive patients with weight loss and obstructive symptoms from an unresectable, malignant esophageal stricture were referred for endoscopic palliation. Fourteen patients did not meet the criteria for YAG laser or BICAP tumor probe treatment and other therapies were recommended. Twenty-eight patients were treated, the first 14 with low-power YAG laser and the last 14 with BICAP tumor probe. All patients had coagulation of malignant strictures in one session. Treated patients were similar in background variables and stricture lengths but twice as much thermal energy was needed for the YAG laser as the BICAP tumor probe treatment. Treatment results were not statistically different during the median follow-up and survival of 16 wk. As minor complications, either pain or edema requiring dilatation was more common in the YAG laser-treated group than the BICAP tumor probe group. Treatment-related esophageal strictures developed in 21% of patients treated with YAG laser. A fistula developed in 1 patient with noncircumferential cancer in the BICAP tumor probe group. Compared with only the intake of liquids before treatment, 86% of patients could eat a soft or solid diet after initial treatment with BICAP tumor probe or YAG laser. Our conclusions were that for BICAP tumor probe and YAG laser, endoscopic palliation efficacy and safety for circumferential esophageal cancer strictures were similar. The advantages of using the BICAP tumor probe were portability, lower equipment costs, and the ability to treat submucosal, long, or high esophageal cancer strictures in one session. Treatment with YAG laser was safer than BICAP tumor probe for exophytic, noncircumferential cancers because the laser could be directed endoscopically. Use of the BICAP tumor probe is not recommended for noncircumferential esophagogastric cancer strictures.

Adenocarcinoma↗
PubMed1985

Malaria.

Malaria continues to present staggering morbidity and mortality statistics. In this well-detailed article, the authors examine the increased incidence of malaria in many areas, describe the malarial parasites, discuss the clinical course, pathogenesis, diagnosis, and treatment, and address the issues of transfusion malaria, congenital malaria, immunity, chemoprophylaxis, and vaccine.

Adolescent↗
PubMed1985

Cyclosporin-A radioimmunoassay: a modified method for whole blood determination.

Cyclosporin-A levels were determined by radioimmunoassay in plasma or whole blood, using split samples collected from patients receiving this agent as the only form of immunosuppression following allogeneic bone marrow transplantation. In the plasma assay the temperature at which centrifugation took place was critical since the mean levels were approximately 30% higher with separation at 37 degrees C in comparison to 20 degrees C or lower. Furthermore, the level in whole blood samples was 2.4 times higher than that from the matching serum. In addition, anticoagulated blood that had been frozen and then thawed was technically more difficult to pipette and resulted in a recovery of only 83% of the cyclosporin when compared with assay using fresh blood. In contrast, consistent measurements were obtained either when whole blood was stored at 4 degrees C and then well mixed and diluted in buffer immediately prior to use or when such buffered samples were frozen and thawed immediately before analysis. The latter modifications render the whole blood assay a practical and reliable means for monitoring cyclosporin-A concentrations and may avoid excessive and the potentially nephrotoxic levels achieved when plasma levels are held in ranges previously considered therapeutic.

Animals↗
PubMed1979

Bone marrow culture in vitro. A technique for analysis and permanent recording of cellular composition.

The in vitro cloning of haematopoietic progenitor cells derived from blood or bone marrow is now an established technique for the study of normal and abnormal blood formation. In semi-solid agar the results are conventionally recorded as the number of clusters or colonies that grow on the plate under controlled culture conditions. However, the demonstration of detailed morphology within these cellular aggregates remains unsatisfactory. Aspiration techniques are cumbersome and invariably disturb cellular relationships within the supporting matrix while supravital staining is limited by variable uptake of dye by the agar. We describe a method in which the entire cell-containing layer is removed from the Petri dish, fixed, and after mounting on a glass-slide, is air-dried. This preparation stains well with a wide variety of biological dyes, is minimally influenced by background colouration of the culture medium and excellent demonstration of morphologic detail is possible. A permanent record of the cellular composition of the culture is easily obtained by mounting the stained agar disc.

Animals↗
PubMed1976

Acute leukaemia and allogeneic granulocyte support.

Infusion of functional allogeneic granulocytes is rational therapy in pyrexial patients with severe neutropenia when combined with appropriate antibiotic administration. On the basis of our first year's experience we endorse this approach, but emphasise the need for further critical evaluation of these cells, and present an approach to placing this procedure on a more scientific basis.

Acute Disease↗
PubMed1975

Spindle cell carcinoma (pseudosarcoma) of the larynx.

"Pseudosarcoma", initially considered a benign response of connective tissue to an adjacent squamous carcinoma, is now regarded as a spindle cell variant of epidermoid carcinoma. Nine cases of spindle cell carcinoma of the larynx are presented. Characteristically, the lesion appears as a large, gray, polypoid tumor. In contrast to other reports, a correlation between gross morphology and prognosis could not be made. The prognosis is more closely related to the size and location of the tumor. Biopsy specimens of the tumors in seven of the nine cases showed only the spindle cell pattern. This may be confused with granulation tissue. Spindle cell carcinoma was metastatic to the neck and lungs in three patients. Our average follow-up time was 3.8 years with two of the nine patients dying of recurrent disease. Most of our patients were successfully treated with conservation surgery.

Adult↗