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Biomedical subjects

A K House

Publications and source records attributed to A K House.

At least 55 records · Page 3Linked to original sources
PubMed1992

Influence of prazosin on experimental vein graft intimal thickening.

The influence of prazosin on experimental vein graft intimal thickening was studied in a rat model. The iliolumbar vein was grafted into the common iliac artery in a prazosin-treated group (n = 17) and a control group (n = 23). Three weeks after grafting the animals were killed and the grafts harvested. Longitudinal sections were prepared and the intimal thickness measured in the proximal, mid and distal graft. Intimal thickness varied considerably in both groups. Median (range) intimal thicknesses for the control group were: proximal 50 (10-120) microns; mid 30 (10-70) microns; and distal graft 30 (10-100) microns. Results for the prazosin-treated group were: proximal 70 (10-160) microns; mid 25 (5-60) microns; and distal graft 25 (5-135) microns. There was no statistically significant difference in median intimal thicknesses between the control and treated groups.

Anastomosis, Surgical↗
PubMed1992

Altered in vitro lymphocyte response in childhood nephrotic syndrome.

The immune system, and disturbed T lymphocyte function in particular, has previously been implicated in the pathogenesis of childhood idiopathic nephrotic syndrome. As this disorder is commonly responsive to steroid therapy, we set out to determine whether in vitro suppression of lymphocyte blastogenic response to the mitogen phytohaemagglutinin (PHA) could predict the clinical situation. Comparing nine nephrotic children with nine healthy controls we were able to show the inhibitory prednisolone dose that suppressed lymphocyte blastogenesis by 50% (ID50) at a known concentration of PHA was significantly greater (P < 0.005) for nephrotic individuals. However, the in vitro assay did not reliably predict the clinical response to prednisolone. This study further implicates altered lymphocyte function in the mechanisms underlying idiopathic nephrotic syndrome.

Adolescent↗
PubMed1992

The value of technetium-99M renography for the detection of renal artery stenosis in patients with aortic and lower limb vascular disease.

The results of technetium renography were compared with arteriography to determine whether this is a satisfactory screening test for renal artery stenosis (RAS). Sixty-three patients were studied before aortic surgery. All were investigated by aortography and isotope renography. These tests were assessed blind and all arteriograms were graded by a single independent radiologist. Renal artery stenosis was detected by arteriography in 34 (54%) patients. Twenty-three (37%) had mild (less than 50%) stenosis, seven (11%) had moderate (50-80%) stenosis and four (6%) had severe (greater than 80%) stenosis. Of these 34 patients, only 6 (18%) were correctly diagnosed by isotope renography. None of the four with severe stenosis were identified. Isotope renography resulted in six true positives, six false positives, 23 true negatives and 28 false negatives. It was concluded that isotope renography did not fulfil the criteria for a screening test for the detection of RAS and appeared to be of no value in those patients undergoing aortic surgery in whom arteriography was not indicated.

Aged↗
PubMed1991

Phenotype alteration in colon carcinoma cells: effect of in vivo passage?

A panel of rat colon adenocarcinoma cell lines (the Per series) were used to investigate the phenotype and karyotype changes induced by in vivo passage in the subcutis of athymic nude mice. One poorly and one well-differentiated tumor cell line were serially passaged through the athymic nude mouse and then back to the syngeneic rat host. Each of the primary and xenograft cell lines expressed fetal crypt cell ("CaCo") antigens. The well differentiated primary and xenograft lines (Per305, Per305N1, and Per305N2a) were different in each of their growth factor responsiveness in vitro [i.e. epidermal growth factor (EGF), bombesin, vasoactive intestinal peptide], their EGF receptor expression, their secretion of transforming growth factor-alpha, and their exhibition of anchorage independent (A-I) growth capabilities. The poorly differentiated primary and xenograft cell lines were also different but were all capable of A-I growth; their responsiveness to exogenous growth factor stimulation decreased with progressive in vivo passage, as did their basal unstimulated proliferation rate. Cytogenetic alterations detected were those associated with clinical specimens from various stages of malignancy, i. e. aneuploidy, structural aberrations, and marker chromosomes. Genetic and mitogenic individuality of each line demonstrated the diversity of the growth control mechanisms in neoplasms at different stages of progression.

Adenocarcinoma↗
PubMed1991

Heparin reduces the intimal hyperplasia seen in microvascular vein grafts.

The influence of heparin on microvascular vein graft intimal hyperplasia was studied in a rat model. The iliolumbar vein was grafted into the iliac artery in 80 rats. Heparin was delivered via a subcutaneous miniosmotic pump, starting either 2 days before grafting (early heparin group, n = 20) or immediately after grafting (heparin group, n = 30). Saline-containing pumps were placed in the control group (n = 30). Heparin activity was measured at 24 h, and again 3 weeks later when the animals were sacrificed. The grafts were harvested and prepared for histological examination. The intimal thickness was measured at the anastomoses and in the mid-graft region using an eye-piece graticule set at right angles to the graft internal elastic lamina. Heparin significantly reduced the intimal thickness at the anastomoses, from a median of 38 microns (range: 10-100 microns) in the control group to a median of 20 microns (range: 10-150 microns) in the heparin group. A similar reduction was seen in the mid-graft region. Although intimal thickening was reduced in the early heparin group, this reduction failed to reach statistical significance. The possible clinical application is discussed.

Anastomosis, Surgical↗
PubMed1989

Cholelithiasis in a teaching hospital: a review of clinical and post-mortem experiences.

Six hundred and eighty cadavers and 307 patients with gallstones who presented over a three-year period at a WA teaching hospital were studied to assess the prevalence, morbidity and mortality of cholelithiasis. In particular, the outcome of surgical treatment compared with that of conservative treatment was assessed. In the post-mortem series, 17.9%, of men and 29.7% of women either had gallstones or had undergone a cholecystectomy previously. In 12 patients (1.8% of patients over all or 10% of those patients with gallstones), the gallstones were responsible for the death of the patient. In the clinical series, of the 248 patients who were treated surgically, 68 patients suffered one or more non-specific postoperative complications and 10 patients suffered specific postoperative complications. However, only one (0.4% operative mortality) postoperative death occurred, the result of a stroke in a patient with previously-known cerebrovascular disease. Of the 59 patients whose gallstones were treated conservatively, 16 patients developed further complications of cholelithiasis with one patient dying of renal failure that was subsequent to biliary pancreatitis. This study shows that to perform cholecystectomy at an early stage in patients with biliary pain is safe and can abort the progression to more-serious complications.

Adult↗
PubMed1988

Prognostic significance of lymphatic permeation in Dukes' B colorectal cancer.

The survival of 78 patients with Dukes' B colorectal carcinoma was evaluated in relation to the presence (36 patients) or absence (42 patients) of tumour cells within lymphatic capillaries. Age-adjusted survival analysis did not reveal a statistically significant difference in survival between these two groups.

Aged↗
PubMed1987

Single chromosome defect, partial trisomy 1q, in a colon cancer cell line.

The characterization of a single chromosome defect previously reported in a case of inherited nonpolyposis colorectal cancer is the essence of this communication. The defect, originally described as 13p+, is now being defined and the karyotype designated as 46,XY,-13,+der(13)t(1;13)(q32.1;p11).

Cell Line↗
PubMed1987

Interleukin 2 synthesis in the presence of steroids: a model of steroid resistance.

In this study interleukin 2 (IL-2) synthesis by human lymphocytes in the presence and absence of prednisolone in a group of normal subjects has been assessed. An association between suppression in vitro of induced phytohaemagglutinin-blastogenesis by prednisolone and synthesis of IL-2 was found. Those subjects whose lymphocytes are identified as steroid-resistant have significantly higher IL-2 activity in the supernatants of both steroid and non-steroid treated lymphocyte cultures than steroid sensitive subjects. The addition of exogenous IL-2 was found to ablate the suppressive effects of steroids on lymphocyte blastogenesis. These results suggest that significantly greater activity of IL-2 in the culture supernatants of steroid resistant subjects may represent a mechanism for glucocorticoid resistance in vitro and help explain the relationship between increased loss of grafts and steroid resistance in renal allograft recipients.

Adult↗
PubMed1987

Three new rat colon tumour cell lines from 1,2-dimethylhydrazine induced adenocarcinomas: morphology, karyotype and clonogenicity.

Three different tumour cell lines (Per113, Per192, Per237) were established from colon adenocarcinomas induced by 1,2-dimethylhydrazine (DMH) inbred male Wistar/Wag rats. Each cell line had epithelial morphology and an abnormal karyotype. The three cell lines were clonogenic in semi-solid medium, but differed in growth factor response, culture characteristics and karyotype. Each cell line was stimulated differentially by epidermal growth factor (EGF) and bombesin in culture. Only Per192 would passage in vivo in athymic nude mice. Per 113 had modal chromosome number of 70 with multiple structural abnormalities; Per237 had 43 chromosomes with consistent trisomy of chromosome I; 20-25% of the cells in line Per192 were in the tetraploid range with multiple copies of chromosome I.

1,2-Dimethylhydrazine↗
PubMed1986

Colorectal carcinoma in a rat model: suppression of tumour development and altered host immune status following treatment with anti B-lymphocyte serum.

The rate of colonic tumour development and immune capability in rats whose B-lymphocyte function was suppressed by injections of rabbit anti-rat IgM and also given the carcinogen dimethylhydrazine (DMH) were studied. Four rat groups were arranged to receive either DMH + anti-IgM, DMH + normal rabbit serum (NRS), saline + anti-IgM, or saline + NRS. Tumour weight, blood and mesenteric lymph node B-lymphocyte numbers, in vivo allograft response, in vitro lymphocytotoxicity, and leucocyte migration inhibition response (LMI) were recorded fortnightly. Tumour induction was delayed in the DMH + anti-IgM (treated tumour) group, which developed less tumour than the DMH + NRS (untreated tumour) group (p less than 0.001). Spleen cell lymphocytotoxicities were depressed in treated rats when compared to either the saline + anti-IgM (treated control) rats or the untreated rats (P less than 0.02), whereas anti-IgM treatment suppressed lymphocytotoxicity responses in control rats (p less than 0.05). The untreated tumour rats were tumour immune by LMI; however, the treated tumour rats did not express this in vitro tumour immunity. The B-lymphocyte levels in the mesenteric lymph nodes of untreated tumour rats increased with tumour induction (p less than 0.05), whereas in the treated tumour rats B-lymphocyte levels were not similarly stimulated.

Animals↗
PubMed1986

Growth factor-induced proliferative responses of human and DMH-induced rat colorectal tumour cell lines.

The proliferative response of three human and three 1,2-dimethylhydrazine (DMH)-induced rat colon tumour cell lines to mouse epidermal growth factor (mEGF) and human urogastrone was examined in two in vitro assays (3H-thymidine uptake in liquid microculture and clonogenicity in semi-solid medium). In the 3H-thymidine uptake assay, one of three rat and one of three human colon tumour cell lines, i.e., r237 and LIM1215, were stimulated by mEGF. In the clonogenic assay, mEGF stimulated the one clonogenic rat tumour cell line r113, which did not respond in the 3H-thymidine uptake assay, and the human tumour cell line LIM1215. Urogastrone stimulated LIM1215 in both assay systems. The significance of these in vitro patterns of response to growth stimulatory factors is discussed.

1,2-Dimethylhydrazine↗