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Biomedical subjects

W R Johnson

Publications and source records attributed to W R Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1984

Reduction in complement activation from biomaterials by removal of air nuclei from the surface roughness.

The activation of the rabbit complement system by each of three different synthetic materials is reported. Samples of each type of material were subjected to one of two different priming procedures. One priming procedure was intended to remove the air nuclei from the surface roughness of the materials; the other procedure was just the normal one. It was found that the removal of the air nuclei during priming reduced the complement activation by each of the two materials of lower surface tension, but not by a statistically significant amount for the material of highest surface tension, cellophane. For the denucleated samples of the three materials, the amount of complement activation was found to correlate with the critical surface tension of the materials; if the samples of the materials were normally primed, there was no correlation of the amount of complement activation with the critical surface tension of the material.

Air↗
PubMed1984

Altered blood lymphocyte subclasses in patients with ulcerative colitis.

Peripheral blood lymphocytes were studied by flow cytofluorimetry and monoclonal antibody techniques in 107 patients with ulcerative colitis and in 20 healthy controls of similar ages. Total T, T helper (TH), and T cytotoxic/suppressor (TC/S) lymphocytes were defined by the monoclonal antibodies OKT3, OKT4 and OKT8, respectively, while B lymphocytes were defined by surface immunoglobulin. Patients had a significantly (P less than 0.05) lower proportion of TC/S lymphocytes than the controls, and patients with quiescent disease had a reduced proportion of B lymphocytes compared to controls and those with active disease. Patients with marked mucosal dysplasia had a significantly (P less than 0.025) lower proportion of TH lymphocytes and a higher (P less than 0.01) proportion of B lymphocytes than those without dysplasia. There were no significant associations between lymphocyte levels and any other clinicopathological features assessed.

Adult↗
PubMed1984

Conformational stress and anastomotic hyperplasia.

Late failure of synthetic vascular grafts to small-diameter arteries (less than or equal to 4 mm) is commonly due to anastomotic hyperplasia. Theoretic analysis suggests that conformational changes at the anastomosis lead to high localized arterial wall stress caused by increases in radius of curvature of the artery (law of Laplace: tension = pressure X radius). Nine 3 kg rabbits had a plastic insert implanted into the infrarenal aorta. The insert was designed to recreate the conformational changes caused by the anastomosis of a synthetic graft to a small-diameter artery, without significantly altering blood flow. The increase in arterial wall tension created by the insert was calculated to be 80% to 100% over baseline values. Aortography, real-time ultrasound, and computed tomography (CT) scanning were done to confirm the absence of luminal thrombus formation or migration of the insert. Ultrasound and CT scans also confirmed the desired conformational changes in the aorta at the site of the insert. Aortas, with the inserts in place, were removed from 3 days to 6 months after implantation. Implantation times of 1 to 6 months resulted in a hyperplastic subintimal lesion characterized by fibrous tissue deposition, spindle cells (which may have been fibroblasts), and/or smooth muscle cells covered by endothelium. In contrast, two rabbits that had the insert placed and then removed at 1 minute and were allowed to survive for 37 and 72 days, respectively, demonstrated complete healing of the aorta without anastomotic hyperplasia. The arterial wall conformational changes induced in this experiment led to the formation of a lesion consistent with anastomotic hyperplasia. An increase in wall tension may have been the stimulus for this response. Prevention of anastomotic hyperplasia may require a means of uniting a graft to an artery without increasing wall tension.

Animals↗
PubMed1983

The leaking anus.

Explore the source record for details and available documents.

Anal Canal↗
PubMed1983

Tumor recurrence in the abdominal wall scar tissue after large-bowel cancer surgery.

In the Melbourne (Monash) series reviewed here the development of apparently isolated incisional scar tissue recurrences after curative excisions for large-bowel cancer proved unusual. Eleven patients with such a recurrence all died of disseminated disease within four years, and most within 12 months, of its development. This suggests that an incisional recurrence is a manifestation of disseminated cancer rather than isolated implantation.

Abdominal Muscles↗
PubMed1983

The risk of rectal carcinoma following colectomy in ulcerative colitis.

In a series of 1439 patients with ulcerative colitis, managed by one of the authors (E.S.R.H.), surgical resection was performed on 374 patients (26 per cent): colectomy, 273 (subtotal colectomy and mucous fistula, 172, colectomy and primary ileorectal anastomosis, 101); proctocolectomy, 61; and miscellaneous procedures, 40. Of the 172 patients undergoing subtotal colectomy and mucous fistula, 93 (54 per cent) subsequently required rectal excision, 33 (19 per cent) had ileorectal anastomosis performed as a second procedure, and in 46 (27 per cent) the rectum has remained as a mucous fistula. Two hundred seventy-three patients were at risk for the development of rectal cancer after subtotal colectomy; ten patients (3.6 per cent) subsequently developed rectal cancer. The cumulative probability of developing rectal cancer after subtotal colectomy reached 17 per cent at 27 years from disease onset. The tumors were more advanced in stage and of higher grade malignancy than those of a parallel general series of patients with rectal cancer uncomplicated by inflammatory bowel disease. Colectomy and ileorectal anastomosis has been successful for most patients. However, the experience of this series highlights the danger of carcinomatous transformation in the retained rectum, the requirement for regular long-term follow-up, the need for markers of precancerous change, and the value, where relevant, of prophylactic proctectomy.

Adolescent↗
PubMed1983

Mucosal dysplasia. A major predictor of cancer following ileorectal anastomosis.

Fifty patients with ulcerative colitis managed by colectomy and ileorectal anastomosis had rectal biopsies performed in the period 1967 to 1972. Follow-up information was available on all patients. Thirty-nine patients were reviewed and rectal biopsies performed in the 1980 to 1982 period. Three patients had developed rectal cancer in the period 1975 to 1980, and two rectal cancers were detected in the 1980 to 1982 follow-up period. All cancers occurred in patients with a diagnosis of moderate or severe dysplasia in biopsy specimens from the 1969 to 1972 period. The probability of developing rectal cancer after a diagnosis of moderate or severe dysplasia in this series reached 42 per cent at nine years from diagnosis.

Adult↗
PubMed1983

Immunoglobulins intrinsic to colorectal carcinoma: an unfavorable prognostic association with IgM.

Immunoglobulin (Ig) eluates prepared from cell membrane fractions of 50 colorectal carcinomas were found to contain significantly (P less than .001) less IgA and IgM and marginally less IgG than normal colon mucosa. IgA and IgG were present in all tumors, but IgM was present in only 20 of 50 tumors (40%). Small (less than or equal to the median vol) tumors contained significantly (P less than .05) more IgA and IgG per gram tissue than did large tumors. Tumors with a large (greater than the median) proportion of stroma contained more IgG than did those with less stroma. No associations were found between Ig and amount of viable-appearing tumor tissue, necrosis, mucin production, and staging. Patients whose tumors contained measurable amounts of IgM had a significantly (P = .012) shorter survival than did patients without intrinsic IgM (12 and 27 mo at the 75th percentile, respectively). The difference could not be explained by conventional staging.

Adenocarcinoma↗
PubMed1983

Fracture studies on a mammalian semicircular canal.

In the present work the pressures necessary to fracture the semicircular canal of the mammalian inner ear, specifically the squirrel monkey, have been investigated experimentally. The results indicate that individual canals can fracture when subjected to internal pressures of approximately 1.6 +/- 0.4 MPa. Simulation testing using Plexiglas and polycarbonate specimens, to represent the location of a possible osteoclast site within the bone forming a semicircular canal, demonstrates further that fracture of the canal can be initiated at this or even lower pressures when the pressure is generated within a simulated osteoclast site. These results provide useful information for a better understanding of the mechanisms by which bubble nucleation and growth could cause pressures of this magnitude within an osteoclast cavity during the decompression phase of a diving schedule.

Animals↗
PubMed1982

Resection of lung metastases in large bowel cancer.

A series of 14 patients had partial or, in one case, total excision of the lung for metastatic tumour originating in the large bowel. Two patients have survived long periods (9 years and 12 years) and are now apparently free of the disease. A third patient shows no recurrence after bilateral lobectomy 2 years ago. Six of the remaining 11 patients developed isolated pulmonary metastases 5 years and 4 months to 11 years and 4 months after the original bowel resection. All 6 survived for 9 months to 11 years after pulmonary resection before succumbing to the disease. In all 11 patients who died, death was caused by systemic metastases in the brain, spinal cord or bone.

Adenocarcinoma↗