A dual high-energy radiography platform with 15 µm resolution at the National Ignition Facility.

To study matter at extreme densities and pressures, we need mega laser facilities such as the National Ignition Facility as well as creative methods to make observations during timescales of a billionth of a second. To facilitate this, we developed a platform and diagnostic to characterize a new point-projection radiography configuration using two micro-wires irradiated by a short pulse laser system that provides a large field of view with up to 3.6 ns separation between images. We used tungsten-carbide solid spheres as reference objects and inferred characteristics of the back-lighter source using a forward-fitting algorithm. The resolution of the system is inferred to be 15 µm (using 12.5 µm diameter wires). The bremsstrahlung temperature of the source is 70-300 keV, depending on laser energy and coupling efficiency. By adding the images recorded on multiple stacked image plates, the signal-to-noise of the system is nearly doubled. The imaging characterization technique described here can be adapted to most point-projection platforms where the resolution, spectral contrast, and signal-to-noise are important.

Simultaneous application of microbial transglutaminase and high hydrostatic pressure to improve heat induced gelation of pork plasma.

The effects of treating porcine plasma with microbial tranglutaminase (MTGase) under high hydrostatic pressure (HHP) were studied as a means of improving its gel-forming properties when subsequently heated at pH 5.5, near the pH of meats. Plasma containing varying levels of commercial MTGase was pressurized (400MPa, room temperature, pH 7) for different times, and adjusted to pH 5.5 prior to heating to induce gelation. MTGase-treatment under HHP led to greater enhancement of heat-induced plasma gel properties as compared to control samples. The greatest improvements were achieved by pressurising plasma with 43.3U MTGase/g protein for 30min, thereby achieving recoveries of 49% and 63% in fracture force (gel strength) and fracture distance (gel deformability) of the subsequently heat-induced gels, respectively, relative to gel properties obtained by heating untreated plasma at physiological conditions (pH 7.5).

Inhibition of protease in intact fish fillets by soaking in or injection of recombinant soy cystatin or bovine plasma.

Arrowtooth flounder (AF) fillets are known to contain a heat-activated cysteine protease similar to that found in Pacific whiting, which results in soft texture upon cooking. A crude recombinant soy cystatin (CRSC) produced by Escherichia coli, which has been shown to inhibit the protease(s) in Pacific whiting, was introduced into AF fillets by immersion or injection at one of three levels of inhibitory activity: 10 times less than, equal to, or 10 times greater than that of a 20% bovine plasma protein (BPP) solution, a known inhibitor of AF protease(s). Fillets treated with CRSC or BPP at equal inhibitory strength subsequently exhibited the same degree of protection against textural degradation during cooking. Fillets treated with CRSC at lesser or greater levels of inhibitory activity than those of BPP exhibited lesser or higher protection, accordingly. As revealed by SDS-PAGE, the outer portion of fillets soaked with inhibitory solutions was more effectively protected than the inner portion. Such differences between the outer and inner portions of the fillets were not evident when inhibitory solutions were injected into the fillets.

Meningioma of the fourth ventricle.

Meningiomas are primary meningeal based tumors of the central nervous system that rarely are located strictly within the fourth ventricle. We report a 72-year-old man operated upon for such a tumor. The pre-operative magnetic resonance images revealed a well circumscribed mass in the fourth ventricle that exhibited a low signal on T1-weighted magnetic resonance images and homogenously enhanced with gadolinium. By light microscopy the tumor was composed of tightly packed spindle cells separated by collagen. Immunohistochemistry showed the tumor cells to be positive for vimentin and epithelial membrane antigen, and negative for glial fibrillary acidic protein. Electron microscopy revealed typical findings of meningioma, including interdigitating cell processes, desmosomes, and intermediate filaments. Although rare, fibroblastic meningioma must be included in the differential diagnosis of a fourth ventricular spindle cell tumor in elderly patients.

High pressure processing effects on fish proteins.

Salted pastes of surimi, a myofibrillar concentrate of fish muscle, gel at pressures near 300 MPa. High pressure processing has been thought to induce denaturation and gelation of myofibrillar proteins mainly by disruption of protein intramolecular hydrophobic interactions which subsequently reform intennolecularly. We have shown that pressure-induced surimi gels evidence disulfide bonding as well. Endogenous transglutaminase (TGase) evidently survives the pressure treatment, and subsequent TGase-mediated setting of Alaska pollock surimi pastes at 25 degrees C results in very strong gels as compared to those prepared without prior pressurization. High pressure during freezing or thawing greatly accelerates these operations and can reduce ice crystal size and associated tissue damage. Yet pressure treatment can destabilize proteins which might lower fish quality. Infusion of certain carbohydrates into muscle prior to pressure-assisted freezing/thawing can achieve both baroprotection and cryoprotection of the muscle proteins. Pressure treatment has not proven useful for inactivation of proteolytic enzymes that degrade fish quality.

Tophaceous pseudogout.

We present an unusual case of tophaceous pseudogout in the atlantoaxial joint with progressive cervical cord compression symptoms and lack of additional clinical manifestations of CPPD crystal deposition disease. This represents only the fourth reported case in the medical literature.

Pharmacokinetics of dirithromycin in patients with impaired hepatic function.

Dirithromycin is a new macrolide antibiotic. A non-blinded, non-comparative study was performed in patients with mild, (Pugh and Childs Grade A) chronic, stable, impaired hepatic function (CSIHF) to determine the single- and multiple-dose pharmacokinetics and safety in such patients. Eight volunteers had disease affecting primarily the hepatic parenchyma, eight had primarily biliary system diseases and five healthy volunteers served as the control population. CSIHF patients and healthy volunteers all received a single dose of dirithromycin 500 mg po and 2 weeks later a 10-day course of dirithromycin 500 mg po once a day. Blood and urine samples were obtained with single dose administration and on days 1 and 10 of multiple-dose administration. The area under the serum concentration versus time curve (AUC) was higher with multiple-dose administration than with single-dose administration in all three treatment groups; however, the difference was not statistically significant between the treatment groups. With multiple-dose administration, peak serum concentrations (Cmax) were 0.69 +/- 0.74, 0.34 +/- 0.15, and 0.78 +/- 0.25 mg/L and the AUC0-24 were 6.45 +/- 6.27, 4.05 +/- 1.59, and 6.60 +/- 2.89 mg.h/L in normal, parenchymal, and biliary volunteers, respectively. Cmax and AUC were consistently lower in subjects with parenchymal disease than those with biliary disease or normal volunteers but the reason for this is unclear. Statistically significant differences in clearance, due to lower non-renal and renal clearances in the biliary volunteers with single- or multiple-dose administration were found between the groups but these differences were not thought to be clinically or pharmacokinetically relevant for short-term antibiotic administration. With dirithromycin administered for 14 days or less, no dosage adjustment should be necessary in patients with mild hepatic insufficiency.

Use of chuck muscles and their acceptability in restructured beef/surimi steaks.

Ten major muscles along with any unidentifiable lean, were carefully excised from 16 Choice square-cut chucks Yield Grade 2, and placed according to previously determined tenderness rankings, into one of three muscle groups. Group 1 was composed of the most tender muscles, and contained the infraspinatus, longissimus, and triceps brachii. Group 2 contained intermediate tenderness muscles and was composed of the serratus ventralis, deep pectoral, and complexus. Group 3 contained the least tender muscles and was composed of the biceps brachii, supraspinatus, rhomboideus, trapezius, deltoids, and neck muscles. Each group was restructured into beef/surimi steaks and was evaluated. Total muscle yield before trimming accounted for 66.2% of the chuck. Careful fat trimming, desinewing, and internal seam cutting on individual muscles resulted in 34.7% lean available for the restructuring of steaks. The triceps brachii, longissimus, supraspinatus, and infraspinatus required the least trimming and were easiest to excise. These muscles made up 49% of the trimmed meat and 13.7% of the total chuck. Steaks were evaluated by a consumer sensory panel for tenderness, flavor, overall preference, and intent to purchase. There were no differences detected by consumers among the muscle groups for the sensory traits studied. Tenderness and flavor were rated equal to intact steaks for all muscle groups studied. The consumer sensory panel indicated that Groups 1 and 2 would be purchased twice a month and Group 3 once a month.

Effect of the peroxisome proliferator LY171883 on hepatocellular replication in female B6C3F1 mice.

LY171883 was shown to increase the incidence of hepatocellular carcinomas and other proliferative lesions in female B6C3F1 mice. This appeared to be unrelated to the induction of peroxisomal beta-oxidation. Experiments were conducted to determine the effect of dietary LY171883 for 7 or 94 days on hepatocellular replication using continuous 7-day infusion of bromodeoxyuridine. LY171883 caused a dose-related increase in hepatocyte replication during the first 7 days, with statistical significance in the two higher dose groups. There was no effect on hepatocyte replication after 94 days of treatment. Liver weight and peroxisomal beta-oxidation were increased in the two higher dose groups after 7 and 94 days, indicating there was not a general loss of hepatic responsiveness to LY171883. The data indicate that the hepatocarcinogenesis of LY171883 in female B6C3F1 mice is not associated with sustained replication in the general population of hepatocytes. It is possible that a mitogenic effect of LY171883 exerted on spontaneously initiated cells is involved in the development of the proliferative lesions; however, further work is needed to determine this.

Hepatocellular DNA synthesis in rats given peroxisome proliferating agents: comparison of WY-14,643 to clofibric acid, nafenopin and LY171883.

The mitogenic effects of peroxisome proliferating agents have been implicated in their carcinogenicity. WY-14,643 stimulates an increase in hepatocellular DNA replication that persists with continued administration, but it is unclear if other peroxisome proliferators share this property. In these studies, WY-14,643 was compared to clofibric acid, nafenopin and LY171883 given to rats in the diet for up to 30 days. DNA replication in the rat liver was quantified by immunohistochemical methods after continuous s.c. infusion of bromodeoxyuridine by osmotic minipump. During the first 7 days of treatment, WY-14,643 (0.1% in diet) and nafenopin (0.05%) increased the percentage of bromodeoxyuridine-labeled hepatocytes to greater than 50%, from 3% in controls. Clofibric acid (0.5%) and LY171883 (0.3%) increased the labeling to approximately 33%. The replicative response to each of the compounds was localized primarily to the periportal region of the liver lobule. The time-course of replication induced by clofibric acid and WY-14,64.3 was examined over 3 day intervals. The peak of replication in response to clofibric acid occurred during days 4-6, whereas the effect of WY-14,643 peaked during days 1-3 and was much greater than clofibric acid. The replicative response to WY-14,643 persisted through 30 days at dietary concentrations of 0.1 and 0.005%. Nafenopin, LY171883 and clofibric acid were without effect on DNA replication on days 28-30 even though the hepatomegaly and induction of peroxisomal beta-oxidation persisted. Thus, under the conditions of these experiments, the persistent replicative effect through 30 days was unique to WY-14,643. Although sustained replication in the general population of hepatocytes may be involved in the carcinogenesis of WY-14,643, it does not appear to be a factor in the hepatocarcinogenesis of the other peroxisome proliferators.

Selective inhibition of cholesterol synthesis in liver versus extrahepatic tissues by HMG-CoA reductase inhibitors.

Hepatic specificity of inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase may be achieved by efficient first-pass liver extraction resulting in low circulating drug levels, as with lovastatin, or by lower cellular uptake in peripheral tissues, seen with pravastatin. BMY-21950 and its lactone form BMY-22089, new synthetic inhibitors of HMG-CoA reductase, were compared with the major reference agent lovastatin and with the synthetic inhibitor fluindostatin in several in vitro and in vivo models of potency and tissue selectivity. The kinetic mechanism and the potency of BMY-21950 as a competitive inhibitor of isolated HMG-CoA reductase were comparable to the reference agents. The inhibitory potency (cholesterol synthesis assayed by 3H2O or [14C]acetate incorporation) of BMY-21950 in rat hepatocytes (IC50 = 21 nM) and dog liver slices (IC50 = 23 nM) equalled or exceeded the potencies of the reference agents. Hepatic cholesterol synthesis in vivo in rats was effectively inhibited by BMY-21950 and its lactone form BMY-22089 (ED50 = 0.1 mg/kg p.o.), but oral doses (20 mg/kg) that suppressed liver synthesis by 83-95% inhibited sterol synthesis by only 17-24% in the ileum. In contrast, equivalent doses of lovastatin markedly inhibited cholesterol synthesis in both organs. In tissue slices from rat ileum, cell dispersions from testes, adrenal, and spleen, and in bovine ocular lens epithelial cells, BMY-21950 inhibited sterol synthesis weakly in vitro with IC50 values 76- and 188-times higher than in hepatocytes; similar effects were seen for BMY-22089. However, the IC50 ratios (tissue/hepatocyte) for lovastatin and fluindostatin were near unity in these models. Thus, BMY-21950 and BMY-22089 are the first potent synthetic HMG-CoA reductase inhibitors that possess a very high degree of liver selectivity based upon differential inhibition sensitivities in tissues. This cellular uptake-based property of hepatic specificity of BMY-21950 and BMY-22089, also manifest in pravastatin, is biochemically distinct from the pharmacodynamic-based disposition of lovastatin, which along with fluindostatin exhibited potent inhibition in all tissues that were exposed to it.

Comparison of 5-bromo-2-deoxyuridine and [3H]thymidine for studies of hepatocellular proliferation in rodents.

Hepatocyte replication traditionally has been studied by [3H]thymidine (TdR) incorporation into DNA, and more recently using incorporation of 5-bromo-2-deoxyuridine (BUdR), a synthetic analog of thymidine which is measured by immunohistochemistry. In studies to compare TdR and BUdR, mice were given the peroxisome proliferator [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid (WY-14643) in the diet (0.1%) for 5 days and either TdR (1 microCi/g) or BUdR (100 mg/kg) on days 2-5. The labeling index (LI) for hepatocytes of WY-14643-treated mice was 4.7% with BUdR and 5.2% with TdR. The LI for control mice was 0.3-0.4% with either label. Partially hepatectomized rats given TdR had a mean LI of 30.0 versus 32.0% in rats labeled with BUdR. Sham-operated controls given TdR had a mean LI of 0.2% and BUdR controls had a mean LI of 0.1%. Hepatectomized rats given TdR and BUdR simultaneously had an LI of 20.1% for TdR and 22.4% for BUdR. In these rats, 94.1% of the labeled cells contained both markers, whereas 1.9% had only TdR and 4.0% had only BUdR. Comparable labeling indices using either TdR or BUdR indicate that the analogs may be used interchangeably in short-term in vivo studies of liver cell proliferation.