Dorsal fracture of the hamate: distinctive radiographic appearance

Six patients who injured their wrists had radiographs documenting a dorsal, 5- to 10-mm oblong fragment of bone immediately proximal to the base of the fourth and/or fifth metacarpal bones. The fragment was seen on the pronation oblique and/or lateral projections, but not on the posteroanterior projection. The radiographic appearance of the fragment was remarkably similar in all cases. In the one patient in which it was performed, pluridirectional tomography demonstrated that the fragment originated from the dorsal surface of the hamate. Five of the six patients also had associated posterior dislocation of the fourth and/or fifth metacarpals. We conclude that this fragment represents a coronal fracture through the body of the hamate resulting from posterior dislocation or subluxation of the fourth and/or fifth metacarpal.     

Increase in survival time of liver transplants by protease inhibitors and a calcium channel blocker, nisoldipine

Kupffer cells are activated by calcium and release a variety of toxic mediators, including proteases. The purpose of these studies, therefore, was to determine if protease inhibitors and a calcium channel blocker could increase survival time in the rat model of orthotopic liver transplantation. Survival for 30 days was greater than 90% in this model when livers were stored for 1 hr in Ringer's solution (survival conditions)--however, grafts stored for 4 hr in Euro-Collins solution or 8 hr in University of Wisconsin (UW) solution survived postoperatively only 1.2 and 0.7 days, respectively (nonsurvival conditions). When livers were stored for 4 hr in Euro-Collins containing a cocktail of protease inhibitors (leupeptin, pepstatin A, phenylmethylsulfonyl fluoride, 20 ng/ml each; diisopropyl fluorophosphate, 100 microM) and subsequently transplanted, however, survival time was increased significantly to 11.5 days. Inclusion of a calcium channel blocker, nisoldipine (1.4 microM), in the protease inhibitor cocktail increased survival time to 23 days. Actually, nisoldipine alone increased survival time to 25 days. Nisoldipine alone also increased survival time in livers stored for 8 or 16 hr in UW solution to between 15 and 20 days. Serum transaminase levels reached peak values greater than 2400 U/L one day postoperatively in the nonsurvival groups, and liver injury assessed histologically was apparent. Under these conditions, pulmonary infiltration of inflammatory cells was observed in about 60% of the lungs examined and was associated with massive bleeding. Inclusion of the protease cocktail, nisoldipine, or both in the storage solutions decreased maximal SGOT levels and injury to both liver and lung significantly by about 50% postoperatively. Nisoldipine also decreased phagocytosis of carbon particles by the perfused liver 2- to 3-fold following storage under nonsurvival conditions (half-maximal effect = 0.3-0.4 microM nisoldipine). Moreover, nisoldipine improved hepatic microcirculation. It accelerated blood flow into the liver, as indexed by hemoglobin reflectance from the liver surface. These data support the hypothesis that Kupffer cells are activated early in the sequence of events that causes graft failure leading to endothelial cell-mediated alterations in the microcirculation. This work demonstrates clearly that dihydropyridine-type calcium channel blockers such as nisoldipine may be clinically useful in storage solutions for liver prior to transplantation.     

Mutagenicity of benzo(a)pyrenyl-1-sulfate in the Ames test.

Comparison of the mutagenicity of nine isomeric benzo(a)pyrenyl [B(a)P] phenols conjugated with either sulfate or glucuronide was carried out using strain Salmonella typhimurium TA98. Of the nine conjugates tested, only B(a)P-1-sulfate was mutagenic. Accordingly, the mutagenicity of B(a)P-1-sulfate was compared with that of B(a)P and 1-hydroxybenzo(a)pyrene [B(a)P-1-OH] in the presence and absence of rat lung S9 and Aroclor-induced liver S9 with and without an NADPH-generating system. B(a)P-1-sulfate was slightly mutagenic, whereas B(a)P and the 1-hydroxy derivative were nonmutagenic when S9 fractions and NADPH were omitted. Addition of induced liver S9 with NADPH caused mutagenicity with B(a) -1-OH greater than B(a)P greater than B(a)P-1-sulfate. B(a)P-1-sulfate was the only mutagenic species when lung S9 was added. This mutagenicity did not require NADPH. Sodium sulfite, an inhibitor of arylsulfatase, decreased the mutagenicity of B(a)P-1-sulfate. These data suggest that a unique mutagenic species is generated from B(a)P-1-sulfate via arylsulfatase in rat lung.     

Inhibition of glucuronidation of benzo(a)pyrene phenols by long-chain fatty acids

Long-chain fatty acids inhibit glucuronidation of benzo(a)pyrene phenols in perfused liver; therefore, this study was designed to investigate interactions of fatty acids with beta-glucuronidase, glucuronosyl transferase, and energy supply. In beta-glucuronidase-deficient C3H/He mice, infusion of oleate (250 microM) increased the release of free benzo(a)pyrene phenols from 14 to 33 nmol/g/h and decreased release of glucuronides into the perfusate from 25 to 17 nmol/g/h. Rates of accumulation of glucuronides in the liver were also diminished from 11 to 4 nmol/g/h after infusion of oleate (250 microM). Fatty acids did not affect the release of benzo(a)pyrene metabolites into bile, and the ratio of free phenol to glucuronide production was increased from 0.57 to 1.30. A similar trend was observed in livers from DBA/2 mice that have beta-glucuronidase. Rates of hydrolysis of benzo(a)pyrene-O-glucuronide were not altered in isolated microsomes by addition of oleoyl coenzyme A (CoA) or octanoyl CoA (10- approximately 100 microM). Thus, we conclude that fatty acids do not alter glucuronidation by acting on beta-glucuronidase. The concentration of cofactors (UDP-glucuronic acid, UDP-glucose, and adenine nucleotides) involved in hepatic conjugation was not altered by infusion of concentrations of oleate (300 microM) that inhibited glucuronidation in perfused livers. When oleate concentrations were increased to 600 microM, UDP-glucuronic acid and UDP-glucose decreased 44 and 49%, respectively, and the ATP:ADP ratio declined concomitantly. Oleoyl CoA inhibited UDP-glucuronosyl transferase noncompetitively (half-maximal inhibition, 10 microM) in microsomes with 3-hydroxy-benzo(a)pyrene or p-nitrophenol as substrate. In contrast, octanoyl CoA was a very poor inhibitor of transferase activity. Inhibition of the transferase by oleoyl CoA was increased markedly by treatment with detergents (Triton X-100), i.e., half-inhibition of glucuronosyl transferase was obtained with about 2 microM oleoyl CoA. Inhibition of UDP-glucuronosyl transferase by oleoyl CoA was also increased in a dose-dependent manner by albumin, possibly due to increasing access of the CoA derivative to the enzyme. Collectively, these data indicate that fatty acids diminish glucuronidation via the formation of acyl CoA compounds that inhibit UDP-glucuronosyl transferase noncompetitively.     

Conjugation of benzo(a)pyrene 7,8-dihydrodiol-9,10-epoxide in infant Swiss-Webster mice.

Benzo(a)pyrene 7,8-dihydrodiol-9,10-epoxide (BPDE), accepted as the ultimate carcinogen of benzo(a)pyrene, has a very short half-life in aqueous solutions yet induces lung tumors when injected into infant mice. To evaluate the possibility that metabolites of BPDE, principally in the form of stable conjugates, contribute to binding to DNA in peripheral tissues, infant mice were injected i.p. with 39 nmol (+/- ) anti-BPDE. One h after injection, 5% of the dose was recovered in serum and appeared mostly as conjugated metabolites (54% as glucuronides and 16% as glutathione conjugates). Amounts of direct acting electrophiles in serum estimated by trapping with DNA comprised less than 0.02% of the injected dose. No more than 10% of the radioactivity in extracts of liver, lung, and kidney was recovered as BPDE. Glutathione conjugates predominated in the liver and lung, whereas glucuronides were the major metabolites in kidney. Radioactivity bound to DNA in liver, lung, and kidney was 21.5, 42.7, and 7.8 pmol/mg, respectively. Despite the rapid conversion of BPDE to stable conjugates, 32P-postlabeling profiles of DNA adducts in lung closely resembled that noted after addition of BPDE directly to lung homogenate. Thus, the reactive intermediate as well as stable conjugates of BPDE may be transported to target tissues where they initiate tumors.     

Radiological images on personal computers: Introduction and fundamental principles of digital images

This series of articles will explore the issues related to displaying, manipulating, and analyzing radiological images on personal computers (PC). This first article discusses the digital image data file, standard PC graphic file formats, and various methods for importing radiological images into the PC.     

NADPH oxidase activity of neutrophil specific granules: requirements for cytosolic components and evidence of assembly during cell activation

Neutrophils and other phagocytic cells support host defense by ingesting microbes and destroying them with reactive oxygen species or oxygen independent mechanisms. Production of ROS is initiated by the phagocyte NADPH oxidase (phox), an enzyme system composed of several constituents. During activation of the cell cytosolic phox proteins (p47phox, p67phox, p40phox, and Rac2) translocate to the plasma membrane and specific granules fuse with the plasma membrane increasing the amount of flavocytochrome b(558). The resultant assembly of phox components results in formation of a complete complex and expression of activity. In this study, we evaluated the oxidase activity of specific granules. In the SDS cell-free system, specific granules expressed oxidase activity in the presence of cytosol in a manner similar to plasma membrane. In contrast to plasma membrane, activity of specific granules was latent, diminishing rapidly over time. In addition, this subcellular fraction contained an inhibitor, possibly related to contamination with azurophilic granules explaining previously published discrepant results. Experiments with recombinant p47phox, p67phox, and dilute cytosol or fractionated cytosol as a source of Rac demonstrated that specific granules have requirements identical to specific granules for oxidase activity. Finally, analysis of neutrophils stimulated with PMA demonstrated translocation of p47phox and to p67phox to specific granules as well as plasma membrane. Both plasma membrane and specific granules from PMA stimulated cells expressed oxidase activity with addition of NADPH demonstrating an assembled oxidase complex. These studies establish a critical role for specific granules as a site for assembly and activation of the oxidase enzyme system and an important constituent for the microbicidal activity of the neutrophil.