Recurrence of subsquamous dysplasia and carcinoma after successful endoscopic and radiofrequency ablation therapy for dysplastic Barrett's esophagus

Barrett's esophagus with dysplasia is commonly treated with radiofrequency ablation (RFA). Despite its effectiveness, a concern of any ablative technique is the development of subsquamous intestinal metaplasia, which could have potential for future neoplastic progression. To date, 34 cases of subsquamous neoplasia have been described in the literature after various ablation therapies. However, only three cases of subsquamous neoplasia have been reported after successful RFA treatment of dysplastic Barrett's esophagus. In this case series, we report on four additional cases of subsquamous neoplasia detected after successful endoscopic resection and RFA for neoplastic and dysplastic Barrett's esophagus. All four patients were treated successfully with endoscopic resection of their recurrent subsquamous neoplastic and dysplastic lesions. This case series highlights the need for continued surveillance following successful treatment of dysplastic Barrett's esophagus with RFA.

Purification and characterization of a beta-glucosidase from Citrus sinensis var. Valencia fruit tissue

A preliminary survey demonstrated activity for alpha-D-glucosidase, alpha-D-mannosidase, alpha-L-arabinosidase, beta-D-glucosidase, beta-D-xylosidase, and beta-D-galactosidase in orange fruit flavedo and albedo tissue. alpha-L-Rhamnosidase was not detected. Subsequently, a beta-glucosidase was purified from mature fruit rag tissue (composed of intersegmental septa, squeezed juice sacs, and fruit core tissue) of Citrus sinensis var. Valencia. The beta-glucosidase exhibited low levels of activity against p-nitrophenyl-beta-D-fucopyranoside (13.5%) and p-nitrophenyl-alpha-D-glucopyranoside (7.0%), compared to its activity against p-nitrophenyl-beta-D-glucopyranoside (pNPG, 100%). The enzyme was purified by a combination of ion exchange (anion and cation) and gel filtration (Superdex and Toyopearl HW-55S) chromatography. It has an apparent molecular mass of 64 kDa by denaturing electrophoresis or 55 kDa by gel filtration chromatography (BioGel P-100). Hydrolysis of pNPG demonstrated a pH optimum between 4.5 and 5.5. At pH 5.0 the temperature optimum was 40 degrees C. At pH 5.0 and 40 degrees C the K(m) for pNPG was 0.1146 mM and it had a V(max) of 5.2792 nkatal x mg(-1) protein (katal = 0.06 International Units = the amount of enzyme that produces, under standard conditions, one micromol of product per min). Of the substrates tested, the enzyme was most active against the disaccharide cellobiose (1-->4), but was not active against p-nitrophenyl-beta-D-cellobioside. High levels of activity also were observed with the disaccharides laminaribiose (1-->3), gentiobiose (1-->6), and sophorose (1-->2). Activity greater than that observed with pNPG was obtained with the flavonoids hesperetin-7-glucoside and prunin (naringenin-7-glucoside), salicin, mandelonitrile-beta-D-glucoside (a cyanogenic substrate), and sinigrin (a glucosinolate). The enzyme was not active against amygdalin, coniferin, or limonin glucoside.

Accumulation of macrophages in primary sclerosing cholangitis

OBJECTIVES

To determine what changes are occurring in patients with primary sclerosing cholangitis (PSC) by examining perisinusoidal macrophages (Kupffer cells) in liver biopsies; 2-to measure transforming growth factor beta (TGFbeta) as a marker of fibrosis in these patients.

DESIGN AND METHODS

Transmission electron microscopy and immunohistochemistry of 15 PSC, 26 primary biliary cirrhosis (PBC), 30 alcoholic liver disease (ALD) and 51 with normal histology was used. Five PSC, 30 ALD and 120 normal volunteers were sampled for serum levels of TGFbeta.

RESULTS

There was a three-fold increase in relative numbers of Kupffer cells in PSC compared to PBC and to patients whose livers had normal histology. In PSC there was an accumulation of perisinusoidal macrophages, which was not associated with focal necrosis or with cholestasis. The levels of TGFbeta in PSC were 54 +/- 2 in cirrhotic versus 34 +/- 5 in non-cirrhotic patients (p < 0.005).

CONCLUSION

The persistent activation of these macrophages may lead to the chronic release of TGFbeta and contribute to chronic inflammation, fibrosis and cirrhosis.

CYP2E1-mediated modulation of valproic acid-induced hepatocytotoxicity

OBJECTIVES

To determine the cytotoxicity of valproic acid (VPA) and its metabolite, 4-ene-valproic acid (4-ene-VPA) in human hepatoblastoma cells (Hep G2), and to study the modulatory effect of cytochrome P450 2E1 induction in this model.

METHODS

Cells were exposed to VPA or 4-ene-VPA in the presence of either ethanol (EtOH), or EtOH combined with disulphiram (DS). Some cells were exposed to alpha-fluoro-VPA or to alpha-fluoro-4-ene-VPA in the absence of CYP2E1 inducers. Apoptosis and necrosis were measured by analyzing 6000 cells per sample using transmission electron microscopy, while cytokine release and apoptosis were quantitated by ELISA.

RESULTS

VPA + EtOH increased VPA cytotoxicity. 4-ene-VPA + EtOH significantly increased toxicity, while DS + EtOH significantly reduced this toxicity. Alpha-fluorinated analogues reduced cytotoxicity compared to the corresponding VPA compounds. Neither VPA nor alpha-fluorinated VPA increased the release of IL-6 or TNF-alpha in media. A significant increase in the release of TNF-alpha was observed in cells exposed to 4-ene-VPA that further increased with EtOH exposure.

CONCLUSIONS

Cells exposed to 4-ene-VPA experience greater cytotoxicity than those treated with VPA. Cytochrome P450 2E1 inducers enhance toxicity in VPA-exposed cells, while alpha-fluorination of VPA diminishes cytotoxicity by directly interfering with the beta-oxidation of the 4-ene-VPA metabolite.

Mechanisms of alcoholic liver disease: cytokines

This article represents the proceedings of a workshop at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was Manuela G. Neuman. The presentations were (1) New aspects of hepatic fibrosis, by D. A. Brenner; (2) Cellular immune response in hepatitis C models, by B. Rehermann; (3) The role of interleukin-10 in acute alcoholic hepatitis, by J. Taieb, S. Chollet-Martin, M. Cohard, J. J. Garaud, and T. Poynard; (4) Cytokine-mediated apoptosis in vitro, by M. G. Neuman; (5) Signaling for apoptosis and repair in vitro, by G. G. Katz, R. G. Cameron, N. H. Shear, and M. G. Neuman; (6) Interferons activate the P42/44 mitogen-activated protein kinase and Janus Kinase signal transducers and activation of transcription (JAK-STAT) signaling pathways in hepatocytes: Differential regulation by acute ethanol via a protein kinase C-dependent mechanism, by B. Gao; (7) Genetic polymorphisms of interleukin-1 in association with the development of Japanese alcoholic liver disease, by M. Takamatsu, M. Yamauchi, M. Ohata, S. Saito, S. Maeyama, T. Uchikoshi, and G. Toda; and (8) Increased levels of macrophage migration inhibitory factor in sera from patients with alcoholic liver diseases, by T. Kumagi, S. M. F. Akbar, M. Abe, K. Michitaka, N. Horiike, and M. Onji.

Acid-catalyzed hydrolysis of hesperidin at elevated temperatures

Dilute sulfuric acid was used as a catalyst for hydrolysis of hesperidin suspensions in water at temperatures ranging from 25 to 180 degrees C. Significant acceleration of the reaction was observed at 120 degrees C and higher temperatures. This increase in the rate of hydrolysis can be attributed to increased solubilization of hesperidin in water at higher temperatures. Partial hydrolysis of hesperidin at 140 degrees C was used for the preparations of hesperetin-7-glucoside, which has a value in the synthesis of dihydrochalcone sweeteners. Simple separation of hesperetin and hesperetin-7-glucoside by extraction with dry acetone or lower alcohols has been developed.

A comparison of EGF and MAb 528 labeled with 111In for imaging human breast cancer

Our objective was to compare 111In-labeled human epidermal growth factor (hEGF), a 53-amino acid peptide with anti-epidermal growth factor receptor (EGFR) monoclonal antibody (MAb) 528 (IgG2a) for imaging EGFR-positive breast cancer.

METHODS

hEGF and MAb 528 were derivatized with diethylenetriamine pentaacetic acid (DTPA) and labeled with 111In acetate. Receptor binding assays were conducted in vitro against MDA-MB-468 human breast cancer cells. Biodistribution and tumor imaging studies were conducted after intravenous injection of the radiopharmaceuticals in athymic mice bearing subcutaneous MCF-7, MDA-MB-231, or MDA-MB-468 human breast cancer xenografts or in severe combined immunodeficiency mice implanted with a breast cancer metastasis (JW-97 cells). MCF-7, MDA-MB-231, JW-97, and MDA-MB-468 cells expressed 1.5 x 10(4), 1.3 x 10(5), 2.7 x 10(5), and 1.3 x 106 EGFR/cell, respectively in vitro.

RESULTS

111In-DTPA-hEGF and 111In-DTPA-MAb 528 bound with high affinity to MDA-MB-468 cells (Ka of 7.5 x 10(8) and 1.2 x 10(8) L/mol, respectively). 111In-DTPA-hEGF was eliminated rapidly from the blood with < 0.2% injected dose/g (%ID/g) circulating at 72 h after injection, whereas 111In-DTPA-MAb 528 was cleared more slowly (3%ID/g in the blood at 72 h). Maximum localization of 111In-DTPA-hEGF in MDA-MB-468 tumors (2.2 %ID/g) was 10-fold lower than with 111In-DTPA-MAb 528 (21.6 %ID/g). There was high uptake in the liver and kidneys for both radiopharmaceuticals. Tumor-to-blood ratios were greater for 111In-labeled hEGF than for MAb 528 (12:1 versus 6:1), but all other tumor-to-normal tissue ratios were higher for MAb 528. MDA-MB-468 and JW-97 tumors were imaged successfully with both radiopharmaceuticals, but tumors were more easily visualized using 111In-labeled MAb 528. There was no direct quantitative relationship between EGFR expression on breast cancer cell lines in vitro, and tumor uptake of the radiopharmaceuticals in vivo, but control studies showed that tumor uptake was receptor mediated.

CONCLUSION

Our results suggest that the tumor uptake in vivo of receptor-binding radiopharmaceuticals is controlled to a greater extent by their elimination rate from the blood than by the level of receptor expression on the cancer cells. Radiolabeled anti-EGFR MAbs would be more effective for tumor imaging in cancer patients than peptide-based radiopharmaceuticals such as hEGF, because they exhibit higher tumor uptake at only moderately lower tumor-to-blood ratios.

111In-labeled EGF is selectively radiotoxic to human breast cancer cells overexpressing EGFR

Our objective was to determine whether the internalization and nuclear translocation of human epidermal growth factor (hEGF) after binding to its cell surface receptor (EGFR) could be exploited to deliver the Auger electron emitter 111In into EGFR-positive breast cancer cells for targeted radiotherapy.

METHODS

hEGF was derivatized with diethylenetriamine pentaacetic acid (DTPA) and radiolabeled with 111In-acetate. The internalization of 111In-DTPA-hEGF by MDA-MB-468 breast cancer cells (1.3x10(6) EGFRs/cell) was determined by displacement of surface-bound radioactivity by an acid wash. The radioactivity in the cell nucleus and chromatin, isolated by differential centrifugation, was measured. The effect on the growth rate of MDA-MB-468 or MCF-7 (1.5x10(4) EGFRs/cell) cells was determined after treatment in vitro with 111In-DTPA-hEGF, unlabeled DTPA-hEGF, or 111In-DTPA. The surviving fraction of MDA-MB-468 or MCF-7 cells treated in vitro with 111In-DTPA-hEGF was determined in a clonogenic assay. The radiotoxicity in vivo against normal hepatocytes or renal tubular cells was evaluated by measuring alanine aminotransferase (ALT) or creatinine levels in mice administered high amounts of 111In-DTPA-hEGF (equivalent to human doses up to 14,208 MBq) and by light and electron microscopy of the tissues.

RESULTS

Approximately 70% of 111In-DTPA-hEGF was internalized by MDA-MB-468 cells within 15 min at 37 degrees C and up to 15% was translocated to the nucleus within 24 h. Chromatin contained 10% of internalized radioactivity. The growth rate of MDA-MB-468 cells was decreased 3-fold by treatment with 111In-DTPA-hEGF (45-60 mBq/cell). Treatment with unlabeled DTPA-hEGF caused a 1.5-fold decrease in growth rate, whereas treatment with 111In-DTPA had no effect. Targeting of MDA-MB-468 cells with up to 130 mBq/cell of 111In-DTPA-hEGF resulted in a 2-logarithm decrease in their surviving fraction. No decrease in the growth rate or surviving fraction of MCF-7 cells was evident. There was no evidence of hepatotoxicity or renal toxicity in mice administered high amounts of 111In-DTPA-hEGF. Radiation dosimetry estimates suggest that the radiation dose to an MDA-MB-468 cell targeted with 111In-DTPA-hEGF could be as high as 25 Gy with up to 19 Gy delivered to the cell nucleus.

CONCLUSION

111In-DTPA-hEGF is a promising novel radiopharmaceutical for targeted Auger electron radiotherapy of advanced, hormone-resistant breast cancer.

Purification of citrus peel juice and molasses

Citrus peel juice and molasses are extremely bitter and unpalatable byproducts of orange and grapefruit juice production. Major components of interest are soluble sugars, glucose, fructose, and sucrose, which account for 60-70% of the dry solids. Analyses indicate that the remaining components are suspended tissue fragments, proteins, organic acids, mineral ions, phenolic compounds, and polyols. A purification sequence that removed a majority of bitter limonoids and phenolic compounds by adsorption on nonionic, macroporous resins was tested. Residual phenolic compounds were removed by adsorption on activated carbon or anion-exchange resin, which also removed anions of organic and inorganic acids. Taste panel results suggested that debittered products could be acceptable for food uses.

Ethanol-induced apoptosis in vitro

OBJECTIVES

The aim is to study the apoptotic process in a human hepatocyte model for ethanol (EtOH)-induced apoptosis.

DESIGN AND METHODS

Normal human primary hepatocytes (HPH) and Hep G2 cells were exposed to increasing EtOH. 6000 cells/ sample were analyzed by transmission electron microscopy.

RESULTS

Apoptotic cells were observed (mmol/L EtOH): 40: 6 +/-0.5%, 60:13 +/- 2% (p < 0.05), 80: 26 +/- 1% (p < 0.001) (vs. control). Two consecutive doses of 80 mmol/L for 24 h each additionally increased apoptosis 55 +/- 3% (p < 0.0001 vs. control and p < 0.001 vs. single dose). In response to this exposure, there is a stronger apoptotic activity in HPH when compared to Hep G2 (p < 0.05).

CONCLUSIONS

In vitro, EtOH-induced apoptosis is regulated by dose level and the frequency of exposure.

Inducers of cytochrome P450 2E1 enhance methotrexate-induced hepatocytoxicity

OBJECTIVES

To study the effect of cytochrome P450 2E1-inducers on methotrexate (MTX)-induced cytotoxicity in human hepatocytes, and investigate the role of silymarin in preventing this toxicity.

DESIGN AND METHODS

Cells were exposed to MTX in the presence of either ethanol (EtOH) or acetaminophen (APAP), or either combined with silymarin (S). Apoptosis and necrosis were measured by analyzing 6000 cells/sample using transmission electron microscopy, while cytokine release and apoptosis were quantitated by ELISA. Cytokine expression was measured by RT-PCR. Gluthatione (GSH) content was determined in cytosolic (c) and mitochondrial (m) fractions.

RESULTS

MTX+EtOH and MTX+APAP increased MTX cytotoxicity 2.9-fold and 1.9-fold, respectively. S abolished this toxicity. MTX + EtOH increased the release of IL 6, IL 8 and TNF alpha by 1.0, 1.2, and 1.1 times, respectively. Cytokine expression was upregulated versus control for IL 6 (22%), IL 8 (38%), and TNF alpha (29%). Addition of 0.5 mmol/L S downregulated TNF alpha expression and reduced cytokine release. TNF alpha increased cytotoxicity by 22%, while anti-TNFalpha antibody eradicated it. MTX+EtOH depleted 45% mGSH (0 < 0.001) while S replenished it to 87% (p < 0.001), when both were compared to control levels.

CONCLUSIONS

Cytochrome P450 2E1-inducers contribute to increase oxidative stress in MTX-exposed cells by increasing TNF alpha and depleting both cGSH and mGSH. This enhances MTX-cytotoxicity and promotes apoptosis.

Novel morphologic findings in alcoholic liver disease

OBJECTIVES

To study light and electron microscopic changes in alcohol-liver disease (ALD) patients, and characterize the expression pattern of Kupffer and stellate cells, correlating changes with serum cytokine levels.

DESIGN AND METHODS

Liver biopsies studied in 35 ALD patients were compared to 51 normal histology patients. Quantitation was done using immunochemistry for Kupffer cells and morphometry, electron microscopy for stellate cells. ELISA was used to measure serum cytokines in 80 controls and ALD patients.

RESULTS

Biopsies of ALD patients confirmed increased number of perisinusoidal, multivesicular, and stellate cells compared to controls. There was a significant increase in the number and activity of multivesicular stellate cells in ALD patients (p < 0.001). These changes were associated with significant increase in the degree of perisinusoidal collagenisation (p < 0.001). The number of Kupffer cells, serum tumor necrosis factor (TNFalpha), interleukins-6 (IL-6) and IL-12 levels, were also significantly higher in ALD patients than controls.

CONCLUSIONS

In non-cirrhotic ALD, stellate cells may be involved in lipid transport and a cytokine network may influence liver inflammation.

Effect of juice extractor settings on juice cloud stability

Juice was extracted from Valencia oranges using three different extractor settings. Differential juice cloud stability was observed. Soft-extracted juice was the most stable, and hard-extracted juice was the least stable. The medium-extracted juice had intermediate cloud stability. Yearly (1997 versus 1998) differences were observed, but the relationship among the juices did not change. Addition of protein extracts, obtained from each juice, to pasteurized juice also resulted in differential cloud stability. Using pectinmethylesterase (PME) activity estimated at pH 4.5, the effects of the protein extract mirrored results from raw juice. Estimating PME activity at pH 7.5 produced contradictory results, indicating that predicting consequences of PME activity estimated at pH 7.5 is unreliable.

Zonal location of compensatory hepatocyte proliferation following chemically induced hepatotoxicity in rats and humans

Hepatocyte proliferation stimulated by partial hepatectomy occurs first in periportal cells, with midlobular and then perivenous cell division occurring later. We have previously shown that this pattern of compensatory cell proliferation also occurs following the hepatotoxicity of N-nitrosodimethylamine. We examined the generality of this pattern in livers of rats given a minimally toxic dose of an hepatotoxin and in liver biopsy samples from patients who had taken overdoses of acetaminophen. Proliferating hepatocytes were detected immunohistochemically (5'-bromodeoxyuridine or Ki-67 antigens). The perivenous necrogens N-nitrosodiethylamine, carbon tetrachloride (CCl4), bromobenzene, and acetaminophen all induced periportal hepatocyte proliferation. With CCl4, bromobenzene, and acetaminophen, the initial appearance of proliferating periportal hepatocytes was followed 12-24 hr later by division in the midlobular region, with a few cells dividing adjacent to the perivenous region of necrosis. The periportal necrogen allyl alcohol also induced periportal cell division. In the human studies, perivenous necrosis was accompanied by periportal and midlobular hepatocyte proliferation. These results suggest that regardless of its lobular location chemically induced hepatotoxicity stimulates cell proliferation that begins in the periportal zone and then moves in an orchestrated response into the midlobular and perivenous zones.

Long-term safety and effectiveness of iron-chelation therapy with deferiprone for thalassemia major

BACKGROUND

Deferiprone is an orally active iron-chelating agent that is being evaluated as a treatment for iron overload in thalassemia major. Studies in an animal model showed that prolonged treatment is associated with a decline in the effectiveness of deferiprone and exacerbation of hepatic fibrosis.

METHODS

Hepatic iron stores were determined yearly by chemical analysis of liver-biopsy specimens, magnetic susceptometry, or both. Three hepatopathologists who were unaware of the patients' clinical status, the time at which the specimens were obtained, and the iron content of the specimens examined 72 biopsy specimens from 19 patients treated with deferiprone for more than one year. For comparison, 48 liver-biopsy specimens obtained from 20 patients treated with parenteral deferoxamine for more than one year were similarly reviewed.

RESULTS

Of the 19 patients treated with deferiprone, 18 had received the drug continuously for a mean (+/-SE) of 4.6+/-0.3 years. At the final analysis, 7 of the 18 had hepatic iron concentrations of at least 80 micromol per gram of liver, wet weight (the value above which there is an increased risk of cardiac disease and early death in patients with thalassemia major). Of 19 patients in whom multiple biopsies were performed over a period of more than one year, 14 could be evaluated for progression of hepatic fibrosis; of the 20 deferoxamine-treated patients, 12 could be evaluated for progression. Five deferiprone-treated patients had progression of fibrosis, as compared with none of those given deferoxamine (P=0.04). By the life-table method, we estimated that the median time to progression of fibrosis was 3.2 years in deferiprone-treated patients. After adjustment for the initial hepatic iron concentration, the estimated odds of progression of fibrosis increased by a factor of 5.8 (95 percent confidence interval, 1.1 to 29.6) with each additional year of deferiprone treatment.

CONCLUSIONS

Deferiprone does not adequately control body iron burden in patients with thalassemia and may worsen hepatic fibrosis.

Multivesicular stellate cells in primary biliary cirrhosis

Stellate cells have only recently received attention in patients with primary biliary cirrhosis (PBC). We have used electron microscopy and morphometry to perform a qualitative and quantitative examination of lipid-storing activity of stellate cells in liver biopsies of 26 patients with noncirrhotic and cirrhotic PBC. In parallel with this study, a comparative analysis of the morphology of stellate cells in 51 patients with livers of normal histology was performed. There was a marked increased in the total number of lipid vesicles in stellate cells in all PBC patients when compared with livers with normal histology. Multiple multivesicular stellate cells were seen in the livers of 21 of 26 patients with PBC. There were 11 to 28 lipid vesicles per multivesicular stellate cell in sizes of 1 microm to 5 microm in diameter per lipid vesicle. Hepatocytes showed little or no steatosis in 24 of 26 (92%) PBC patients. Multivesicular stellate cells were not seen in female patients with normal liver histology. These results suggest that there is an alteration in hepatic lipid storage that involves stellate cells in PBC that could be an early manifestation of this disease. Its significance remains to be elucidated.

Multivesicular stellate cells in primary biliary cirrhosis

Stellate cells have only recently received attention in patients with primary biliary cirrhosis (PBC). We used electron microscopy and morphometry to perform a qualitative and quantitative examination of lipid-storing activity of stellate cells in liver biopsies of 26 patients with noncirrhotic and cirrhotic PBC. Parallel with this study, a comparative analysis of the morphology of stellate cells in 51 patients with livers of normal histology was performed. There was a marked increase in the total number of lipid vesicles in stellate cells in all PBC patients when compared to livers with normal histology. Multiple multivesicular stellate cells were seen in the livers of 21 out of 26 patients with PBC. There were 11 to 28 lipid vesicles per multivesicular stellate cell from 1 micromol/L to 5 micromol/L in diameter per lipid vesicle. Hepatocytes showed little or no steatosis in 24 out of 26 (92%) PBC patients. Multivesicular stellate cells were not seen in female patients with normal liver histology. These results suggest that there is an alteration in hepatic lipid-storage that involves stellate cells in PBC, which could be an early manifestation of this disease. Its significance remains to be determined.

Gastrointestinal, hepatic, and metabolic effects of enteral and parenteral nutrition in rats infused with tumor necrosis factor

BACKGROUND

We previously showed that continuous infusion of tumor necrosis factor-alpha (TNF-alpha) in orally fed rats caused weight and muscle wasting mainly because of anorexia. However, when we tried to prevent weight loss by giving total parenteral nutrition (TPN), TNF-infused rats developed hyperglycemia, azotemia, and hepatic abnormalities. The present study was designed to determine whether the enteral (ENT) feeding resulted in fewer complications than parenteral (TPN) feeding in TNF-infused rats (100 micrograms/kg/d).

METHODS

Forty-two rats were randomly allocated to four groups as follows: controls: TPN and ENT, and TNF-infused: TPN + TNF and ENT + TNF. All groups received the same liquid defined formula diet either enterally or parenterally (isocaloric and isonitrogenous). Twenty-six rats were used for studies of body composition and metabolism and 16 for vascular permeability.

RESULTS

TPN + TNF and ENT + TNF rats showed significantly increased liver weights and significantly reduced carcass weights compared with controls. A significant reduction in the muscle weights and total protein, as well as hyperglycemia, azotemia, and abnormal liver enzymes was also seen in ENT + TNF rats compared with ENT rats. The gastric and small intestinal mucosa was inflamed in the ENT + TNF but not in the ENT, TPN + TNF, and TPN rats. The plasma TNF levels determined by bioassay were significantly increased in the TPN + TNF and ENT + TNF rats compared with controls. There was increased vascular permeability in the stomach and small and large intestine in the ENT + TNF rats compared with ENT rats. No significant changes in vascular permeability were seen in TPN and TPN + TNF rats.

CONCLUSIONS

ENT, but not TPN, resulted in prominent changes in the body composition and marked metabolic effects in the TNF-infused rats.

Allele-specific PCR analysis of p53 codon 249 AGT transversion in liver tissues from patients with viral hepatitis

AGG to AGT mutations in codon 249 of the p53 tumor-suppressor gene are frequently observed in hepatocellular carcinomas (HCC) from areas where exposure to aflatoxin B1 (AFB) occurs. We developed a sensitive allele-specific polymerase chain reaction (AS-PCR) assay to detect this point mutation in non-neoplastic human liver tissues. Three oligonucleotide primers, 1 specific for the mutant allele and 2 specific for the wild-type allele were used. The mutant allele primer differed from the wild-type allele due to a G-to-T transversion in its terminal 3' nucleotide. The first stage involved amplification of exon 7 of p53 followed by a selective amplification of mutant codon 249 sequences. This method allowed for the detection of a mutant codon 249 allele in the presence of as many as 105 copies of the wild-type allele and was 100-fold more sensitive than the restriction fragment length polymorphism-PCR technique. We have applied this AS-PCR protocol to examine codon 249 AGT transversion in tumor and matched non-tumor liver samples from North American patients with hepatitis and from Mozambiquan patients exposed to AFB. Mutations were detected in 5 of 6 samples of non-neoplastic liver from Mozambiquan patients, all of whom were HBsAg- or HBcAg-positive and AFB-exposed. In contrast, no mutations were detected in non-neoplastic liver from North American patients with either HBV- or HCV-derived hepatitis and cirrhosis. This procedure is a simple and powerful approach for screening p53 codon 249 AGT mutation in heterogeneous non-neoplastic hepatocyte populations.

A comparison of the effects of oral prednisone and inhaled beclomethasone dipropionate on circulating leukocytes

BACKGROUND

While the side effects of oral glucocorticoids are well recognised there is debate about the systemic effects of high doses of inhaled glucocorticoids such as beclomethasone dipropionate and how these compare with the effects of oral prednisone.

AIMS

To compare the effects of different doses of oral prednisone and inhaled beclomethasone dipropionate (BDP) on changes in circulating leukocytes.

METHODS

Changes in different subsets of circulating leukocytes were measured as an index of the systemic effects of inhaled BDP and oral prednisone. We compared the effects of inhaled placebo and 500 and 1000 micrograms of inhaled BDP with oral placebo and 2.5, 5 and 10 mg of prednisone in eight healthy volunteers. Leukocyte numbers were measured before and four hours after each dose of medicine.

RESULTS

Compared with inhaled placebo, 1000 micrograms of inhaled BDP led to a significant increase in neutrophils as a percentage of the total white count (p < 0.05) and a significant decrease in the total lymphocyte number (p < 0.05) and in the number of CD4 lymphocytes (p < 0.05). For 1000 micrograms BDP the increase in the % neutrophil count was 8.55% (95% CI 5.17 to 11.93) and the fall in lymphocyte numbers was -0.14 x 10(9)/L (95% CI 0.06 to -0.34) while 2.5 mg prednisone led to an increase in the % neutrophil count of 9.31% (95% CI 5.82 to 12.80) and a fall in lymphocyte numbers of -0.07 x 10(9)/L (95% CI 0.05 to -0.19).

CONCLUSIONS

The systemic effects of 1000 micrograms inhaled BDP and 2.5 mg of prednisone are similar.

Allele-specific PCR analysis of p53 codon 249 AGT transversion in liver tissues from patients with viral hepatitis

AGG to AGT mutations in codon 249 of the p53 tumor-suppressor gene are frequently observed in hepatocellular carcinomas (HCC) from areas where exposure to aflatoxin B1 (AFB) occurs. We developed a sensitive allele-specific polymerase chain reaction (AS-PCR) assay to detect this point mutation in non-neoplastic human liver tissues. Three oligonucleotide primers, 1 specific for the mutant allele and 2 specific for the wild-type allele were used. The mutant allele primer differed from the wild-type allele due to a G-to-T transversion in its terminal 3' nucleotide. The first stage involved amplification of exon 7 of p53 followed by a selective amplification of mutant codon 249 sequences. This method allowed for the detection of a mutant codon 249 allele in the presence of as many as 105 copies of the wild-type allele and was 100-fold more sensitive than the restriction fragment length polymorphism-PCR technique. We have applied this AS-PCR protocol to examine codon 249 AGT transversion in tumor and matched non-tumor liver samples from North American patients with hepatitis and from Mozambiquan patients exposed to AFB. Mutations were detected in 5 of 6 samples of non-neoplastic liver from Mozambiquan patients, all of whom were HBsAg- or HBcAg-positive and AFB-exposed. In contrast, no mutations were detected in non-neoplastic liver from North American patients with either HBV- or HCV-derived hepatitis and cirrhosis. This procedure is a simple and powerful approach for screening p53 codon 249 AGT mutation in heterogeneous non-neoplastic hepatocyte populations.

Overexpression of cytochrome P-450 isoforms involved in aflatoxin B1 bioactivation in human liver with cirrhosis and hepatitis

Studies were carried out to test the hypothesis that inflammatory liver disease increases the expression of specific cytochrome P-450 isoenzymes involved in aflatoxin B1 (AFB) activation. The immunohistochemical expression and localization of various human cytochrome P-450 isoforms, including CYP2A6, CYP1A2, CYP3A4, and CYP2B1, were examined in normal human liver and liver with hepatitis and cirrhosis. The constitutive expression of CYP3A4 in normal liver showed a characteristic pattern of distribution in centrilobular hepatocytes, whereas CYP1A2, CYP2A6, and CYP2B1 were expressed uniformly throughout the liver acinus. In sections of liver infected with hepatitis B virus (HBV) or hepatitis C virus (HCV), the expression of CYP2A6 was markedly increased in hepatocytes immediately adjacent to areas of fibrosis and inflammation. CYP3A4 and CYP2B1 were induced to a lesser degree, and expression of CYP1A2 was unaffected. In HBV-infected liver, double immunostaining revealed that overexpression of CYP2A6 occurred in hepatocytes expressing the HBV core antigen. In HCV-infected liver, CYP2A6, CYP3A4, and CYP2B1 were overexpressed in hepatocytes with hemosiderin pigmentation. These results suggest that alterations in phenotypic expression of specific P-450 isoenzymes in hepatocytes associated with hepatic inflammation and cirrhosis might increase susceptibility to AFB genotoxicity.

Efficacy of deferiprone in the treatment of acute iron intoxication in rats

BACKGROUND

Deferiprone [(1,2-dimethyl-3-hydroxypyrid-4-one) (L1)], is the first orally active iron chelating agent to reach clinical trials in patients with chronic iron overload. Its efficacy in preventing morbidity and mortality in acute iron poisoning has not been tested.

OBJECTIVE

To determine whether deferiprone can reduce the mortality of rats following toxic oral doses of iron.

METHODS

Rats were administered 612 mg/kg elemental iron by gavage, corresponding to the LD58. A parallel group received the same oral dose of iron followed by deferiprone intraperitoneally at 400 mg/kg (loading dose), followed by additional intraperitoneal injections of 200 mg/kg, 100 mg/kg and 100 mg/kg of deferiprone at one hour intervals.

RESULTS

Coadministering deferiprone with the iron decreased mortality from 58% (11/19) to 15% (3/20) (p = 0.013). The administration of deferiprone was associated with urinary excretion of iron (which did not occur with iron alone) and the production of the red deferiprone-iron complex. On histological examination there appeared to be less iron in the liver and gastrointestinal tract.

CONCLUSION

The coadministration of deferiprone can decrease morbidity and mortality caused by acute iron overdose. Deferiprone holds promise for the treatment of iron poisoning but additional study is required.

Fermentation of orange peel hydrolysates by ethanologenic Escherichia coli. Effects of nutritional supplements

Orange peel, an abundant byproduct of the citrus processing industry, is converted to a mixture of glucose, galacturonic acid, fructose, arabinose, galactose, and xylose by hydrolysis with mixed pectinase and cellulase enzymes. All these sugars can be fermented to ethanol or ethanol and acetic acid by the recombinant bacterium Escherichia coli KO11. The fermentation efficiency is improved by the addition of yeast extract, tryptone, mixed amino acids, corn steep liquor, or by proteolytic digestion of endogenous proteins. Batch fermentations of supplemented peel hydrolysate containing 111 g/L of initial total sugars produced 35-38 g/L of ethanol in 48-72 h and a 75-85% yield.

Fermentation of sugars in orange peel hydrolysates to ethanol by recombinant Escherichia coli KO11

The conversion of monosaccharides in orange peel hydrolysates to ethanol by recombinant Escherichia coli KO11 has been investigated in pH-controlled batch fermentations at 32 and 37 degrees C. pH values and concentration of peel hydrolysate were varied to determine approximate optimal conditions and limitations of these fermentations. Very high yields of ethanol were achieved by this microorganism at reasonable ethanol concentrations (28-48 g/L). The pH range between 5.8 and 6.2 appears to be optimal. The microorganism can convert all major monosaccharides in orange peel hydrolysates to ethanol and to smaller amounts of acetic and lactic acids. Acetic acid is coproduced in equimolar amounts with ethanol by catabolism of salts of galacturonic acid.

Effect of tauroursodeoxycholic and ursodeoxycholic acid on ethanol-induced cell injuries in the human Hep G2 cell line

BACKGROUND & AIMS

Taurodeoxycholic acid (TUDCA) and ursodeoxycholic acid (UDCA) exert a protective effect in chronic cholestasis. This study reports the effect of TUDCA and UDCA on an in vitro model for ethanol-induced liver damage.

METHODS

Hep G2 cells were incubated for 24 hours with 80 mmol/L ethanol in the presence or absence of 50 mumol/L TUDCA or UDCA. Cells were also pretreated with 80 mmol/L EtOH and then exposed to 50 mumol/L bile acids. Cytotoxicity was assessed by the metabolism of formazan (3-(4,5-dimethyl-thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide and sodium 3,3'-(phenylamino) carbonyl-3,4-tetrazolium-bis (4-methoxy-6-nitro) benzene sulfonic acid hydrase and by the release into the culture medium of different enzymes (aspartate aminotransferase, glutamate dehydrogenase, gamma-glutamyl transferase, and lactate dehydrogenase).

RESULTS

The incubation of Hep G2 with EtOH significantly (P < 0.001) increased cytotoxicity. Both TUDCA or UDCA reduced cytoxicity to a similar extent (P < 0.001). Cells pretreated with EtOH and then added with TUDCA or UDCA responded differently because TUDCA was significantly more effective (P < 0.05) than an equimolar dose of UDCA in reversing the damage. Electron microscopic examination revealed that TUDCA and UDCA were both able to prevent mitochondrial damage and to reduce steatosis induced by EtOH.

CONCLUSIONS

Low doses of TUDCA and UDCA protect Hep G2 cells from EtOH-induced cytotoxicity. However, TUDCA seems to be more effective than UDCA in reversing the damage.

Severe hepatotoxicity from granulocyte-macrophage colony-stimulating factor administered after autologous bone marrow transplantation

We report a case of life-threatening hepatotoxicity following GM-CSF therapy after autologous bone marrow transplantation. GM-CSF hepatotoxicity should now be considered in the differential diagnosis of post-transplant liver disease.

Iron-chelation therapy with oral deferiprone in patients with thalassemia major

BACKGROUND

To determine whether the orally active iron chelator deferiprone (1,2-dimethyl-3-hydroxy-pyridin-4-one) is efficacious in the treatment of iron overload in patients with thalassemia major, we conducted a prospective trial of deferiprone in 21 patients unable or unwilling to use standard chelation therapy with parenteral deferoxamine.

METHODS

Hepatic iron stores were determined yearly by chemical analysis of liver-biopsy specimens or magnetic-susceptibility measurements. Detailed clinical and laboratory studies were used to monitor safety and compliance.

RESULTS

The patients received deferiprone therapy for a mean (+/-SE) of 3.1 +/- 0.3 years. Ten patients in whom previous chelation therapy with deferoxamine had been ineffective had initial hepatic iron concentrations of at least 80 mumol per gram of liver, wet weight -- values associated with complications of iron overload. Hepatic iron concentrations decreased in all 10 patients, from 125.3 +/- 11.5 to 60.3 +/- 9.6 mumol per gram (P < 0.005), with values that were less than 80 mumol per gram in 8 of the 10 patients (P < 0.005). In all 11 patients in whom deferoxamine therapy had previously been effective, deferiprone maintained hepatic iron concentrations below 80 mumol of iron per gram.

CONCLUSIONS

Oral deferiprone induces sustained decreases in body iron to concentrations compatible with the avoidance of complications from iron overload. The risk of agranulocytosis associated with deferiprone may restrict its administration to patients who are unable or unwilling to use deferoxamine.

Identification, characterization, and partial purification of glucoamylase from Aspergillus niger (syn A. ficuum) NRRL 3135

The crude extracellular extract of Aspergillus niger (syn A. ficuum) NRRL 3135 contains glucoamylase (exo-1,4-alpha-D-glucanohydrolase, EC 3.2.1.2). The enzyme, a glycoprotein, was purified 7-fold by ion-exchange chromatography, chromatofocusing, and conconavalin A affinity chromatography. The molecular weight of the enzyme was estimated to be 90 kDa by SDS-PAGE and gel permeation chromatography. The pI of the enzyme was 3.4. The temperature optimum of the enzyme was 60 degrees C and the pH optimum was 5.0. The Vmax values for soluble starch, maltose, maltotriose, maltotretraose, maltopentaose, and isomaltose were 55.2, 11.7, 32.3, 47.8, 59.2, 12.5 nKat glucose/sec, respectively and the Km values for the same substrates were 0.09%, 0.67 mM, 0.76 mM, 0.76 mM, 0.68 mM, and 122.01 mM, respectively.

Influences of dietary deoxycholic acid on progression of hepatocellular neoplasms and expression of glutathione S-transferases in rats

Serial magnetic resonance imaging (MRI) was used to evaluate the influences of dietary deoxycholic acid (DCA) on the rate of progression of chemically induced hepatocellular neoplasms in rats. Male Fischer-344 rats with established persistent hepatocellular nodules generated by the Solt-Farber protocol were exposed to dietary DCA (0.3%) between 6 and 12 mo of age. Growth of nodules and carcinomas in vivo was measured by morphometric quantification of tumor images obtained every 6 wk. The final stages of neoplastic progression were determined by terminal histopathological examination and by expression and functional evaluation of glutathione S-transferase (GST) isoenzyme phenotypes. Dietary DCA increased the number of hepatocellular neoplasms per rat, accelerated the rate of growth of persistent nodules, and increased the histological progression of liver tumors. Expression of immunoreactive GST subunits Yf, Ya, and Yb1 was induced in early persistent nodules, a pattern that was maintained throughout the study in both basal diet and DCA-fed groups. However, 5% of early nodules and about 75% of advanced neoplasms were partially or completely deficient in GST Yb2 expression in both groups. DCA did not alter the cytosolic activity for the GST substrates 1-chloro-2,4-dinitrobenzene (CDNB) or trans-4-phenyl-3-buten-2-one (tPBO) in tumors or surrounding liver. However, in both groups, CDNB activity was increased in the tumors relative to the surrounding nonneoplastic tissue, whereas activity for tPBO, a substrate more specific for the Yb2 subunit, was reduced in the tumors. All advanced neoplasms were similarly more resistant than surrounding liver to DNA-binding metabolites of aflatoxin B1 or benzo[a]pyrene. These data demonstrate that DCA can increase the progression of established hepatocellular nodules to larger, more advanced neoplasms but does not preferentially select for a specific GST phenotype. Preferential loss of constitutively expressed GST Yb2 in both basal diet and DCA-fed groups may be an important aspect of progression from resistant nodules to advanced cancers in this model. These studies also demonstrate that serial MRI is a useful tool for measuring the rates of enlargement and patterns of growth in established hepatocellular neoplasms.

In situ hybridization for the Y chromosome reveals a donor origin for a posttransplant lymphoproliferative disorder in a sex-mismatched hepatic allograft

We report a case of posttransplant lymphoproliferative disorder diagnosed within 4 weeks of orthotopic liver transplantation from a male donor to a female recipient. To determine whether the posttransplant lymphoproliferative disorder was of donor or recipient origin, nonisotopic in situ hybridization for the human Y chromosome was performed on formalin-fixed, paraffin-embedded sections of the donor liver using a digoxigenin-labeled probe. The lymphoid cells hybridized with the Y chromosome probe, indicative of a male genotype consistent with posttransplant lymphoproliferative disorder of donor origin. This case illustrates that nonisotopic in situ hybridization for the Y chromosome can discriminate between donor and recipient cells in sex-mismatched organ transplants.

Small encapsulated hepatocellular carcinoma of the liver. Provisional analysis of pathogenetic mechanisms

BACKGROUND

Small hepatocellular carcinomas frequently were found incidentally during routine pathologic examinations of adult livers removed at liver transplant.

METHODS

Sixty-nine carcinomas of all sizes were found in 25 patients; 39 of the tumors were smaller than 1 cm in diameter, and 18 of the carcinomas in five patients were not clinically suspected. These small incidental carcinomas lend themselves to analysis of the morphologic basis of human hepatocellular carcinogenesis.

RESULTS

All of these tumors arose in cirrhotic livers. Most of the small carcinomas were multilobulated and subdivided by pre-existing fibrous septa. The surrounding capsule usually was not a true capsule. They were all well differentiated, most formed bile, Mallory bodies, or showed alpha-1-antitrypsin (A1AT) positivity. Transition from cirrhotic nodular parenchyma to areas of hyperplasia or atypical hyperplasia to well-differentiated carcinoma were common. Large cell dysplasia also was common.

CONCLUSIONS

These morphologic transitions closely parallel changes seen in experimental chemical carcinogenesis. They also strongly suggest a multicentric origin of the tumors. In addition, in every instance, the lesions were multiple in the liver and involved both lobes. This latter finding has possible implications for recurrence after local surgical excision of small hepatocellular carcinomas.

The role of hepatocyte heterogeneity in the initiation of hepatocarcinogenesis

N-Nitrosodimethylamine (NDMA) is a carcinogen in rat liver while N-nitrosomethylbenzylamine (NMBzA) produces no liver tumors but is a potent esophageal carcinogen in the rat. Both nitrosamines, however, are metabolically activated in the liver and methylate hepatic DNA. The reasons for their different carcinogenic properties in rat liver are unclear. Here we show that as expected, NDMA produces large numbers of putative initiated hepatocytes that overexpress the placental form of glutathione S-transferase (GST-P+ hepatocytes). Hepatocyte division induced by the hepatotoxic effect of NDMA occurs principally in the periportal region of the liver lobule, while O6-methylguanine formation is principally in the DNA of perivenous cells. These two effects lead to the production of GST-P+ hepatocytes in roughly equal numbers throughout the liver lobule. NMBzA also induces the formation of a small, but significant number of GST-P+ hepatocytes. The NMBzA-induced GST-P+ hepatocytes are localized within the perivenous zone of the liver lobule. Since, unlike NDMA, NMBzA produces no hepatocellular necrosis and hence does not induce regenerative cell division, these results suggest that NMBzA initiates only those hepatocytes adjacent to the hepatic vein that are spontaneously dividing at the time their DNA becomes methylated by the nitrosamine. We used partial hepatectomy to stimulate cell division in specific regions of the liver lobule. When the peak of DNA methylation produced by NMBzA in the perivenous cells coincided with a peak of cell division in that region, an increased number of GST-P+ hepatocytes was induced. Our results suggest that the potency of initiating agents in the liver depends both on their ability to form mutagenic lesions in DNA and to induce division in the specific hepatocytes that contain the modified DNA.

Nutritional, hepatic, and metabolic effects of cachectin/tumor necrosis factor in rats receiving total parenteral nutrition

BACKGROUND

In orally fed animals, infusion of cachectin/tumor necrosis factor (TNF) caused weight loss and muscular wasting, accompanied by anorexia. Despite muscle wasting, there were gains in weight and protein and DNA contents of the viscera, but no significant metabolic abnormalities.

METHODS

To observe the effect of cachectin/TNF on the nutritional-metabolic status, and without the confounding effect of anorexia, cachectin/TNF was infused into rats receiving total parenteral nutrition in sufficient amounts to induce weight gain in controls at the same rate as in orally fed rats.

RESULTS

TPN prevented loss of body weight, but cachectin-treated animals had reduced nitrogen retention and carcass weight. By contrast, there were gains in visceral protein levels, which in the liver was due to a marked proliferation of biliary epithelium. In addition, cachectin-treated animals receiving TPN developed hyperglycemia, hyperosmolality, diuresis, and dehydration. They also had azotemia and cholestasis.

CONCLUSIONS

In the absence of the effects of anorexia, cachectin reduced nitrogen retention and caused metabolic and multisystem dysfunction, comparable with the effects of clinical sepsis.

Utilization of circulating glutathione by nodular and cancerous intact rat liver

The relationship of the rate of extraction of circulating glutathione (GSH) to the level of activity of gamma-glutamyltransferase (GGT) of hepatocytes of nodular and of cancer-bearing livers was studied in rats perfused in situ via the portal vein. Fischer adult male rats with many nodules (10 rats) or few (nine rats) liver nodules and four rats with hepatomas were compared as to their ability to remove GSH (10 microM) from the perfusate. The rate of extraction of infused GSH was directly proportional to the numbers of GGT(+)-hepatocytes in the liver tissue, inhibitable completely by adding the GGT inhibitor serine borate at 6-8 mM in the perfusate, and significantly enhanced in all rats by adding the gamma-glutamyl acceptor glycyl-glycine to the perfusate. These results suggest that nodules and cancers are able to remove GSH much more efficiently from the circulation than the surrounding liver tissue and that their enhanced GSH utilization is directly dependent on their GGT activity, which is present at much higher levels than in the surrounding tissues. The increases in GGT activity in nodule hepatocytes and enhanced ability to utilize GSH could be critical factors in the response to resistance selection of chemical hepatocarcinogenesis.

Comparison of liver cancer and nodules induced in rats by deoxycholic acid diet with or without prior initiation

The neoplastic responses of liver to prolonged continuous exposures of deoxycholic acid (DCA) in the diet with or without prior initiation was examined in Fischer 344 (F-344) and Sprague-Dawley (SD) male rats. In both rat strains, 7 months of continuous feeding of 0.5% (F-344 rats) or 1.0% (SD rats) of deoxycholic acid in chow diet generated hepatic nodules which persisted up to 8 months after deoxycholic acid was stopped. In one group of Sprague-Dawley male rats, 7 months of deoxycholic acid was preceded by an initiating dose of diethylnitrosamine. In 10 out of 15 of these rats, not only persistent nodules but also 26 liver cancers (large, multifocal, invasive, lung metastases) become evident by 8 months after cessation of deoxycholic acid.

Diploid growth pattern of hepatocellular tumours induced by various carcinogenic treatments

Hepatocellular carcinomas from rats of different strains, subjected to a variety of carcinogenic treatment regimens in different laboratories (initiation by diethylnitrosamine or dimethylhydrazine, promotion by phenobarbital, 2-acetylaminofluorene, nafenopin, orotic acid or deoxycholic acid, growth stimulation by partial hepatectomy or necrogenic CCl4 treatment), were all found to be predominantly diploid by flow cytometric analysis, in contrast to normal liver tissue in which polyploid nuclei were predominant. A switch from polyploidization to diploid growth would thus seem to be a common property of malignant liver tumours. Benign neoplastic liver nodules were likewise predominantly diploid, with the exception of nodules induced by long-term deoxycholic acid treatment in Fischer rats. In addition to containing a majority of polyploid cells, the latter nodules failed to progress to the carcinoma stage.

Body composition and metabolic rate in rat during a continuous infusion of cachectin

Changes in brain metabolites, energy balance, resting metabolic rate, body composition, and organ histology were studied over 10 days in control (C), cachectin-infused (CIR), and pair-fed (PFR) (in relation to CIR) rats. The cachectin was continuously infused for the 10 days into the superior vena cava at the rate of approximately 100 micrograms.kg-1.day-1. The brain of the CIR had significantly more tryptophan and 5-hydroxyindole-3-acetic acid than C and PFR. The CIR rats were anorexic, hypermetabolic, relatively hyperglycemic, and had raised blood urea nitrogen with comparable creatinine levels when compared with similarly wasted PFR. They had significant loss of muscle mass, especially in muscles with a predominance of type II fibers. However they gained liver, heart, and lung mass. The loss of muscle mass could be ascribed to dietary deficiency, but the gain in visceral mass was associated with an increase in organ DNA and protein. Histology showed that there was cell proliferation in the liver, heart, and kidneys. The data are consistent with centrally mediated anorexia with nutritionally mediated muscle wasting but with visceral hypermetabolism, protein accumulation, and cell proliferation.

Protective activity of different hepatic cytosolic glutathione S-transferases against DNA-binding metabolites of aflatoxin B1

To evaluate the role of glutathione S-transferase (GST) isoenzymes in induced resistance of hepatocytes to aflatoxin B1 (AFB1), we compared DNA protective activities of different hepatic cytosol preparations and purified GSTs from normal rats, rats exposed to different polychlorinated biphenyls (PCBs), and rats with carcinogen-induced hepatocellular neoplasms, with cytosols or purified GSTs from mouse, rainbow trout, and human livers. These comparisons were performed in an in vitro assay for [3H]AFB1-DNA binding after activation by rat liver microsomes. Cytosol and S-hexylglutathione-affinity-purified GST preparations from livers of mice consistently had strong protective activity against AFB1-DNA binding. The majority of this activity was dependent on the presence of reduced glutathione (GSH) but some GSH-independent protection was observed in mouse hepatic cytosol, but not in purified GST preparations. We found that all of the GSH-dependent DNA-protective activity in mouse liver eluted as a single GST isoenzyme by hydroxyapatite chromatography. Preparations of cytosol and purified GSTs from normal rat liver, rainbow trout liver, and human liver had much less AFB1-specific DNA protective activity than GSTs found in mouse liver preparations. Cytosol from rats with carcinogen-generated liver neoplasms and livers induced with 3,3',4,4'-tetrachlorobiphenyl and 2,2',4,4',5,5'-hexachlorobiphenyl had more GST activity toward CDNB than cytosol from normal rat liver. When equivalent units of GST activity (CDNB) were compared, there was little difference observed between the DNA-protective activities of PCB-induced and normal rat liver cytosols, yet cytosol from rat liver neoplasms was more protective. Purified GST-P (7-7), the GST isoenzyme most induced in carcinogen-generated rat liver neoplasms, was not protective when added at protein concentrations found to be protective for total GSTs isolated from these neoplasms. These studies demonstrate that the resistance of mouse liver to AFB1 can be explained primarily by a single constitutive GST isoenzyme (YaYa or 4-4) with a relatively high activity toward DNA-binding metabolites of AFB1. GST isoenzymes with such high specific DNA protective activity against AFB1 metabolites were not evident in human, rat, or rainbow trout liver or in PCB-induced or neoplastic rat liver preparations.

Sex differences in response to four promotion regimens in spite of common first cellular steps in the hepatocellular cancer process initiated by diethylnitrosamine

Female adult rats were as responsive as males to initiation by diethylnitrosamine (DEN) as measured by numbers of GST-P positive hepatocytes appearing early, and do develop hepatocellular cancers. However, when females and males were exposed to four promotion regimens including orotic acid (OA), choline deficiency, deoxycholic acid (DOC), or selection for resistance (to 2-acetylaminofluorene; 2-AAF) after DEN initiation, very significant sex differences were observed with respect to oval cell proliferation and growth rates of hepatocytic foci. These results suggest that responses to promotion such as growth of foci and oval cell proliferation can accompany carcinogenesis but may not be essential to the development of hepatocellular cancer.

Identification of the putative first cellular step of chemical hepatocarcinogenesis

A first cellular step of chemical hepatocarcinogenesis is characterized by identifying hepatocytes with preneoplastic properties: positivity for glutathione transferase-P or GST-P+, cell proliferation marked by bromodeoxyuridine or BUDR+, resistance to hepatotoxins and persistence. Hepatocellular doublets, both GST-P+ and BUDR+, are located immunohistochemically 4 days after a single dose of diethylnitrosamine, 25 mg/kg, using antibodies bound to different chromogens. GST-P+ hepatocytes proliferate after selection for resistance to 2-acetylaminofluorene, and persist in the absence of selection for 6 weeks. The actual probability of the same cell being GST-P+ and BUDR+ is 200 times the expected value implying close links between cell proliferation and GST-P expression at initiation.

Transfer of C(4) Photosynthetic Characters through Hybridization of Flaveria Species

Transfer of C(4) photosynthetic traits was studied through hybridization of Flaveria trinervia (Spreng.) Mohr (C(4)) and Flaveria brownii A.M. Powell (C(4)-like) with Flaveria linearis Lag. (C(3)-C(4)) and the C(3) species Flaveria pringlei Gandoger (C(3)). Fertility was low, based on irregular chromosome pairing and low pollen stainability, except in F. brownii x F. linearis which had bivalent pairing and 76% stainable pollen. Hybrids had apparent photosynthesis values of 71 to 148% of the midparental means, while the CO(2) compensation concentration was similar to the C(4) or C(4)-like parent, except in hybrids having the C(3) species F. pringlei as a parent. Inhibition of apparent photosynthesis by O(2), and phosphoenolpyruvate carboxylase and NADP-malic enzyme activities and subunit levels in the hybrids were closer to the C(3) or C(3)-C(4) parent. The species F. brownii and F. trinervia were equal in their capacity to transfer reduced O(2) inhibition of AP and CO(2) compensation concentration values to hybrids with F. linearis (C(3)-C(4)), although hybrids with F. trinervia had higher PEPC activity. The O(2) inhibition of AP was correlated with the logarithm of activities of phosphoenolpyruvate carboxylase (r = -0.95) and NADP-malic enzyme (r = -0.87). These results confirm that C(4) traits can be transferred by hybridization of C(3)-C(4) and C(4) or C(4)-like species, with a higher degree of C(4) photosynthesis than exists in C(3)-C(4) species, and at least in F. brownii x F. linearis, fertile progeny are obtained.

Inheritance of c(4) enzymes associated with carbon fixation in flaveria species

Activities and subunit levels of three C(4) enzymes were determined for F(1) hybrids between C(4) and C(3)-C(4)Flaveria species. For phosphoenolpyruvate carboxylase and pyruvate orthophosphate, dikinase, enzyme amounts in the hybrids were close to the mid-parent means. However, activity and subunit levels of NADP-malic enzyme were approximately one-half the mid-parent mean.

Closed-loop control of the partial pressure of arterial oxygen in neonates

A closed-loop control system has been developed to regulate automatically the partial pressure of arterial oxygen (PaO2) to a pre-set level in neonates with RDS (Respiratory Distress Syndrome). A microcomputer-based system is described which uses the PaO2 value from an indwelling umbilical artery electrode as the input to a robust control algorithm. The derived control signal is used to modify the position of a motor driven oxygen/air blender, thus regulating the percentage of oxygen delivered in the inspired gas mixture. The parameters of the control algorithm were conservatively chosen, and the safety aspects of the system are discussed. A total of 48 h of closed-loop control were recorded on seven pre-term infants with mild-to-moderate RDS being nursed in headboxes. Ten separate closed-loop control intervals were recorded, and overall the results showed a marked improvement over comparable periods of manual control. The percentage of time for which the recorded PaO2 was within +/- 1 kPa of the chosen target value (10 kPa) was 74.9 +/- 10.2% when averaged over the ten closed-loop control periods. The corresponding figure for the comparable manual control intervals was 45.2 +/- 16.0%.

Purification and characterization of P-52 (glutathione S-transferase-P or 7-7) from normal liver and putative preneoplastic liver nodules

A previous study from our laboratory (L.C. Eriksson et al., Biochem. Biophys. Res. Commun., 117: 740-745, 1983) revealed that a cytosolic polypeptide of approximate Mr 21,000 (designated P-21) was markedly elevated in amount in hepatocyte nodules induced by six different regimens. The molecular weight of this polypeptide, subsequently revised to approximately 26,000, was redesignated P-26 and was identified (T.H. Rushmore et al., Biochem. Biophys. Res. Commun., 143: 98-103, 1987) as a subunit of a placental form of glutathione S-transferase (K. Sato et al., Gann 75: 199-202, 1984), also named glutathione S-transferase 7-7 (H. Jensson et al., FEBS Lett., 187: 115-120, 1985). We describe here a convenient method for purifying relatively large amounts of P-26 from hepatocyte nodules involving the sequential use of affinity chromatography on S-hexyl glutathione-Sepharose 4B, CM-Sephadex, and DEAE-Sephacel. Evidence is presented that P-26 exists as a dimer of approximate Mr 52,000 (P-52). Analyses by two-dimensional electrophoresis have indicated that the subunits of Mr 26,000 may consist of five separate charged isomers. Investigations using appropriate antisera and analysis by amino acid sequencing have provided additional confirmation that P-52 is probably identical to rat placental glutathione S-transferase. Antibodies to P-52 are proving to be useful as a marker of new cell populations that appear regularly during hepatocarcinogenesis.