Evaluation of the portal venous system before liver transplantation: value of phase-contrast MR angiography.

OBJECTIVE: The purpose of this study was to assess the accuracy of phase-contrast MR angiography with gadolinium in evaluating the patency and blood flow direction of the portal venous system; the presence, extent, and type of varices; and the patency of surgical decompressive shunts in patients before liver transplantation. This information is essential in management and care of patients with chronic liver disease and portal hypertension and those who are candidates for liver transplantation. SUBJECTS AND METHODS: Twenty-four patients with portal venous hypertension were evaluated with phase-contrast MR angiography. Two patients had surgical splenorenal shunts and one had a mesocaval shunt. Phase-contrast angiograms were acquired as a series of two-dimensional sequential coronal sections during breath-holding and after IV administration of gadopentetate dimeglumine. Correlative findings from color flow Doppler sonography, contrast-enhanced CT scanning, and conventional angiography were available in 23, 20, and 10 patients, respectively, and were used as standards. The images from each technique were analyzed independently for patency of and flow direction in the portal vein, splenic vein, superior mesenteric vein, and surgically created shunts, and for detection, distribution, and extent of five variceal groups. RESULTS: Findings from phase-contrast MR angiography completely agreed with those of sonography, CT scanning, and conventional angiography. The main portal vein was patent in 18 patients, stenosed in one, partially thrombosed in one, and occluded in four. Phase-contrast MR angiography correctly showed hepatofugal flow in three patients and hepatopetal flow in 17 patients. Both the splenic and superior mesenteric veins were patent in 20, partially thrombosed in one, and occluded in three cases. Phase-contrast MR angiograms showed 85% of the variceal groups, and MR rating of variceal size was not significantly different from that of CT rating. Phase-contrast MR angiography correctly showed the patency of all three surgical decompressive shunts. CONCLUSION: Phase-contrast MR angiography is accurate for evaluating the patency and flow direction of the portal venous system, detecting and determining the distribution and extent of varices, and assessing the patency of surgically created shunts. Therefore, it is a reliable and noninvasive technique that can provide crucial information in the preoperative workup of liver transplant recipients.

Analysis of milk-based infant formula. Phase IV. Iodide, linoleic acid, and vitamins D and K: U.S. Food and Drug Administration-Infant Formula Council: collaborative study.

In 1982, the U.S. Food and Drug Administration, the Infant Formula Council and its member companies, contract laboratories, and other government laboratories began a study of analytical methods for the nutrients listed in the Infant Formula Act of 1980. Phases I, II, III, and V have been completed. The present report provides data on Phase IV, in which 13 laboratories collaboratively studied an ion-selective electrode method for analyzing iodide, a gas chromatographic method for linoleic acid, and 2 liquid chromatographic (LC) methods each for vitamins D and K. Data were insufficient to evaluate one each of the LC methods studied for vitamins K and D. The relative standard deviations (RSD) are sufficient for the nutrient levels found in infant formula. RSDs (%) for repeatability (RSDr) and reproducibility (RSDR), respectively, were as follows: iodide, 4.0-11.4 and 13.5-18.2; linoleic acid, 1.0-1.6 and 3.5-5.1; vitamin K1, 3.2-16.0 and 6.2-19.4; and vitamin D3, 4.2 and 35.0. The recommendation to adopt the method for vitamin D was supported by the results of a ministudy. All laboratories were capable of using these methods with little training. The methods for determination of iodide, linoleic acid, and vitamins D and K in ready-to-feed milk-based infant formula have been adopted first action by AOAC International.

Infant formulas: evidence of the absence of pesticide residues.

Concern about the effect of potential pesticide residues on the safety of the U.S. food supply has led to extensive modeling and projections of worst-case scenarios. Many risk assessment models project risk based on an assumption of the presence of pesticide residues at the tolerance level or at a level equivalent to the limit of analytical detectability. Often, actual residue data, and the variability of analytical detection limits, are ignored in favor of simpler models. Data presented here demonstrate the absence of detectable levels of pesticides in infant formula. The range of detection limits of analytical methodology employed also are presented. A rationale for the absence of pesticide residues in infant formulas derived from plant and animal sources is presented which obviates worst-case scenario calculations of risk based on pesticide residue tolerance levels or method detection limits.

Analysis of milk-based infant formula. Phase V. Vitamins A and E, folic acid, and pantothenic acid: Food and Drug Administration-Infant Formula Council: collaborative study.

In 1982, the U.S. Food and Drug Administration, the Infant Formula Council and its member companies, contract laboratories, and other government laboratories began a study of analytical methods for the nutrients listed in the Infant Formula Act of 1980 (P.L. 96-359). Four phases of the study have been completed and are discussed in earlier reports. The present report provides data on Phase V, in which 13 laboratories collaboratively studied individual methods for folic acid, pantothenic acid, and vitamin E, in addition to 2 methods for vitamin A. Vitamins A and E are determined by liquid chromatography. Folic acid and pantothenic acid are determined by microbiological methods using acidimetric and/or turbidimetric assays as the determinative step. In most cases, relative standard deviations for repeatability, RSDr, and reproducibility, RSDR, are as good as those that would be predicted from other collaborative studies. RSDr and RSDR values obtained for the 5 methods are 9.35 and 25.44% for folic acid, 4.59 and 10.23% for pantothenic acid, 8.46 and 11.69% for vitamin E, 3.62 and 9.72% for vitamin A (retinol isomers), and 4.9 and 10.5% for vitamin A (retinol). The 5 methods have been adopted first action by AOAC International.

Neutron irradiation of human melanoma cells.

The biological characteristics and in vitro radiosensitivity of melanoma cells to thermal neutrons were investigated as a guide to the effectiveness of boron neutron capture therapy. Plateau phase cultures of three human malignant melanoma-established cell lines were examined for cell density at confluence, doubling time, cell cycle parameters, chromosome constitution, and melanin content. Cell survival dose-response curves, for cells preincubated in the presence or absence of p-boronophenylalanine. HCl (10B1-BPA), were measured over the dose range 0.6-8.0 Gy (N + gamma). The neutron fluence rate was 2.6 x 10(9) n/cm2/s and the total dose rate 3.7 Gy/h (31% gamma). Considerable differences were observed in the morphology and cellular properties of the cell lines. Two cell lines (96E and 96L) were amelanotic, and one was melanotic (418). An enhanced killing for neutron irradiation was found only for the melanotic cells after 20 h preincubation with 10 micrograms/ml 10B1-BPA. In view of the doubling times of the cell lines of about 23 h (96E and 96L) or of 36 h (418), it seems likely that an increased boron uptake, and hence increased radiosensitivity, might result if the preincubation period with 10B1-BPA is extended to several hours longer than the respective cell cycle times.

Morphological changes in human melanoma cells following irradiation with thermal neutrons.

Morphological changes in two human melanoma cell lines, MM96 and MM418, following irradiation with thermal neutrons, were studied using light and electron microscopy. The results show that the response of human malignant melanoma cells to neutron irradiation is both cell line dependent and dose dependent, and that in any given cell line, some cells are more resistant to irradiation than others, thus demonstrating heterogeneity in respect to radiosensitivity. Cells repopulating MM96 flasks after irradiation were morphologically similar to the cells of origin whereas in MM418 flasks cells differentiated into five morphologically distinct subgroups and showed increased melanization. The results also show that radiation causes distinctive morphological patterns of damage although ultrastructural changes unique to the high LET particles released from boron 10 neutron capture are yet to be identified.