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Biomedical subjects

T J Hall

Publications and source records attributed to T J Hall.

125 records · Page 7Linked to original sources
PubMed1979

Cations and the accessibility of chromatin to nucleases.

When rat liver nuclei prepared with polyamines as stabilising cations are digested with DNAase II, release of both inactive chromatin and Mg-soluble, active chromatin is greatly reduced, in comparison to digestion of liver nuclei prepared with Mg2+ as stabilising cation. Chromatin release from polyamine stabilised nuclei is also inhibited relative to Mg-stabilised nuclei following digestion with micrococcal nuclease under two very different cation conditions. Nuclei prepared with polyamines and monovalent ions as stabilising cations exhibit properties intermediate between these two extremes with both nucleases. These effects are due to residual binding of polyamines to chromatin, which is thus maintained in a condensed state, inaccessible to nucleases. Since polyamine binding is not easily reversed, concentrations of polyamines and other cations must be rigidly controlled in experiments on chromatin structure if artefacts are to be avoided. The significance of these findings to the nature and properties of active chromatin within the intact nucleus is considered.

Animals↗
PubMed1979

Choleresis and cholestasis produced by infusion of taurocholic acid or taurodehydrocholic acid combined with BSP in the rhesus monkey.

To study the determinants of BSP Tm in rhesus monkeys, animals with indwelling silastic catheters were infused with sufficient BSP to produce a rising plasma concentration and normal saline or taurocholic acid 3.5 mumol/min, 7.0 mumol/min, or 10.5 mumol/min. BSP Tm was 3.84 +/- 0.11 mg/kg/10 min during normal saline infusion, 5.52 +/- 0.53 mg/kg/10 min during taurocholic acid 3.5 mumol/min, despite greater bile flow with the latter compound. Higher infusion rates of taurocholic acid inhibited BSP Tm and the proportion of conjugated BSP secreted into bile, as well as bile flow and bile acid secretion. Taurodehydrocholic acid 7.0 mumol/min produced similar but less marked effects. These results indicate that bile flow does not explain the effects of bile acids on BSP Tm and suggests that bile acids exert varying effects on BSP transport or binding in micelles. The cholestasis observed with combined BSP and higher bile acid infusion rates is probably due to inhibition of liver cell intermediary metabolism or to liver cell toxicity.

Animals↗
PubMed1978

Prospective evaluation of endoscopic retrograde cholangiopancreatography in the diagnosis of periampullary cancers.

In a prospective study of 112 patients suspected of periampullary cancer endoscopic retrograde cholangiopancreatography (ERCP) was successfully performed in 87 patients (78%). Technical failures were due to gastric outlet obstruction in four patients and inability to cannulate the ampulla of Vater in 21 patients. Successfully performed ERCP had both a high sensitivity (92%) and specificity (90%) for periampullary cancer. The few errors in pancreatogram interpretation were due to juxta-ductal cancers and difficulty in differentiating duct changes of cancer from those of chronic pancreatitis. Pancreatic cytology, performed in 21 patients, was reliable, diagnosed two pancreatic cancers when the pancreatogram failed and, if used routinely, assists interpretation of the pancreatogram. Retrograde cholangiography provided a correct diagnosis in six jaundiced patients with normal pancreatograms. Three complications of ERCP occurred in this series.

Ampulla of Vater↗
PubMed1978

The prognosis of carcinoma of the colon and rectum complicating ulcerative colitis.

Thirty-three carcinomas of the colon and rectum occurring in patients with ulcerative colitis have been compared with matched controls from a population without colitis. There is no difference in length of survival between the patients in the two groups. More extensive tumor spread in the control group is due to the method of selection.

Adenocarcinoma↗
PubMed1977

Pancreatic cancer screening. Analysis of the problem and the role of radionuclide imaging.

The clinical, surgical, and pathologic findings in a five year prospective study of 192 patients referred with a high probability of pancreatic cancer are reported. We have defined the requirements of any pancreatic imaging procedure as its ability to distinguish a normal pancreas from pancreatic cancer or chronic pancreatitis and the capability of detecting tumors less than 5 cm in diameter. There was a 47 percent incidence of pancreatic disease (27 percent pancreatic cancer and 20 percent chronic pancreatitis). Prospective radionuclide imaging as routinely performed was found to be of little clinical value in this patient population; it was neither specific nor sensitive to pancreatic cancer or chronic pancreatitis. Preliminary data with longitudinal multiplane emission tomography show an improved diagnostic accuracy and the ability to detect resectable tumors, but its efficacy needs to be prospectively compared with other screening tests on a carefully defined patient population.

Adenoma↗
PubMed1975

Meckel's bleeding diverticulum diagnosed by mesenteric arteriography.

The details of a young adult patient who presented with chronic gastro-intestinal blood loss as a complication of Meckel's diverticulum are reported. A preoperative diagnosis was made using superior mesenteric arteriography. The merits of superior mesenteric arteriography and other investigations currently available in the diagnosis of Meckel's diverticulum are discussed.

Adult↗
PubMedDate not supplied

Ultrasound contrast-detail analysis: a preliminary study in human observer performance.

Results of a human observer performance study using a new ultrasound contrast-detail (CD) phantom are reported. The new phantom allows estimates of the fundamental statistical uncertainties involved in CD analysis. Results of these experiments show that observers generally considered to be "trained" require experience at the specific task of low-contrast target detection under signal known exactly (SKE) conditions, and that observers require an orientation period at the beginning of each observation session to obtain stable responses. The results obtained in this study can be used to estimate the number of independent images, observers, and repeat observation sessions required for a desired uncertainty in CD curves, and show that 10% fractional standard deviations are obtainable with modest observer effort.

Biometry↗