Biomedical subjects

T Reck

Publications and source records attributed to T Reck.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Contrast-enhanced ultrasound improves hepatic vessel visualization after orthotopic liver transplantation.

BACKGROUND: We investigated whether color-coded Doppler sonography combined with an ultrasound contrast medium would improve the assessment of liver-supplying vessels after orthotopic liver transplantation. METHODS: Forty-seven patients after orthotopic liver transplantation participated. Examinations were done without and then with the ultrasound contrast medium Levovist. Visualization of the liver-supplying vessels was assessed with a scoring system. RESULTS: Visualization of the portal vein was similar without and with contrast medium. Hepatic arteries were visualized in 39 patients without contrast medium and 46 patients with contrast medium. The remaining patient showed hepatic artery thrombosis, which was confirmed angiographically. With the use of Levovist, the examination took 3.7 min rather than the usual 6.4 min. CONCLUSION: Imaging of hepatic arteries after liver transplantation improved significantly with the use of ultrasound contrast medium. These findings are important because the early detection of blood flow through the liver after transplantation affects prognosis.

Adult↗

PubMedDate not supplied

Clinical value of MRC in the follow-up of liver transplant patients with a choledochojejunostomy.

BACKGROUND: We investigated the clinical value of magnetic resonance cholangiography (MRC) in liver transplant patients receiving choledochojejunostomy (CDJ). METHODS: Twenty-five MRCs were performed in 23 initially asymptomatic patients 19 months (mean) after liver transplantation with biliary reconstruction via CDJ. The images were evaluated by consensus (two investigators) for bile duct strictures and dilatations. As a standard of reference, clinical follow-up (including laboratory analysis) was used in 20 cases and direct cholangiography or surgery in three cases. RESULTS: Fourteen pathologic findings were observed in 11 patients (anastomotic strictures in four, left or right bile duct strictures in three, and peripheral segmental dilatations with or without strictures in seven). Patients with pathologic MRC findings had significantly higher levels of alkaline phosphatase (p < 0.05) and more frequently had histories of cholangitis than did patients with normal MRC. Four of six patients with stenoses of the central bile ducts subsequently developed biliary complications requiring treatment (three confirmed by direct cholangiography). In patients with unremarkable bile ducts or only peripherally located changes on MRC, no bile duct complications or relevant changes in the cholestasis parameters occurred during follow-up (mean = 30 months). CONCLUSION: MRC can noninvasively detect pathologic biliary tract changes in liver transplant patients in the asymptomatic stage and provide information for planning invasive therapeutic procedures.

Adult↗

PubMedDate not supplied

Changes in hepatic hemodynamics after orthotopic liver transplantation: color Doppler sonography.

BACKGROUND: Liver perfusion has an influence on therapy results in patients undergoing orthotopic liver transplantation (OLT). The objective of the present study was to investigate changes in hepatic hemodynamics in patients after OLT with color-coded Doppler sonography (CCDS). METHODS: Forty-five consecutive patients were included. The examinations were done before, on postoperative day 1, and then weekly until the patients were discharged. Mean velocity of the portal (PV-V) and splenic (SV-V) veins and the maximum velocity and resistance index of the hepatic artery were determined. RESULTS: After OLT a significant increase in PV-V and SV-V was observed. Twenty-five patients had normal perfusion of the hepatic artery, whereas 16 patients had abnormal flow patterns. In these patients prostaglandin I(2) was used until flow rates normalized. In four patients, CCDS could not detect perfusion of the hepatic artery. CONCLUSIONS: CCDS is a suitable method for evaluating hepatic hemodynamics before and after OLT. Changes in blood flow velocities in the liver-supplying vessels are detectable, but perfusion of the hepatic artery is seldom detectable. These observations are of special interest after OLT, where liver circulation has an influence on therapy results.

Adult↗

PubMedDate not supplied

Pyrrolo[1,4]benzodiazepine antitumor antibiotics: relationship of DNA alkylation and sequence specificity to the biological activity of natural and synthetic compounds.

The DNA alkylation and sequence specificity of a group of natural and synthetic pyrrolo-[1,4]benzodiazepines [P(1,4)Bs] were evaluated by using an exonuclease III stop assay, and the results were compared with in vitro and in vivo biological potency and antitumor activity. The P(1,4)B antibiotics are potent antitumor agents produced by various Actinomycetes, which are believed to mediate their cytotoxic effects by covalent bonding through N-2 of guanine in the minor groove of DNA. In this article we describe the results of a sensitive DNA alkylation assay using exonuclease III which permits both estimation of the extent of DNA modification as well as location of the precise guanines to which the drugs are covalently bound. Using this assay, we have evaluated a series of natural and synthetic compounds of the P(1,4)B class for their ability to bind to DNA and also determined their DNA sequence preference. The compounds included in this study are P(1,4)Bs carrying different substituents in the aromatic ring, having varying degrees of saturation in the five-membered ring, or differing in the stereochemistry at C-11a. These same compounds were evaluated for in vitro cytotoxic activity against B16 melanoma cells, for potency in vivo in B6D2F1 mice (LD50), and for antitumor activity (ILSmax) against P388 leukemia cells. A good correlation was found between extent of DNA alkylation and in vitro and in vivo potency. Furthermore, on the basis of electronic and steric considerations, it was possible to rationalize why those compounds that showed negligible biological activity were unable to bond covalently to DNA. Last, we have determined that the degree of saturation in the five-membered ring of the P(1,4)Bs has a significant effect on the DNA bonding reactivity and biological activity of this class of compounds.

Alkylation↗