Long-term therapy of chronic hepatitis B with lamivudine

Lamivudine therapy induces improvements in chronic hepatitis B in a high proportion of patients, but prolonged therapy is limited by the development of viral resistance. We analyzed clinical responses and virologic resistance in 27 patients treated continuously with lamivudine for 2 to 4 years. Serum transaminases, hepatitis B virus (HBV) DNA by both branched DNA (bDNA) signal amplification and quantitative polymerase chain reaction were monitored at 4- to 8-week intervals. Virologic resistance to lamivudine was confirmed by the presence of mutations in the YMDD motif of the polymerase gene by restriction fragment-length polymorphism analysis. Serum HBV-DNA levels decreased rapidly in all treated patients, falling by 4 to 5 logs within 1 year. Transaminase levels also decreased and were normal in 70% of patients at 1 year, at which point liver histology had improved in 81% of patients. Viral resistance began to emerge after 8 months of therapy, eventually developing in 14 patients, including 76% of hepatitis B e antigen (HBeAg)-positive patients but only 10% of HBeAg-negative patients. Lamivudine withdrawal led to reappearance of wild-type HBV species, but retreatment led to more rapid reappearance of the mutant virus. Clinical, serum biochemical, and histologic improvements were maintained in the 13 patients who did not develop resistance. Thus, long-term therapy with lamivudine resulted in maintained improvements in virologic, biochemical, and histologic features of disease in most patients with HBeAg-negative chronic hepatitis B and in the subgroup of HBeAg-positive patients with high serum transaminase levels. A high rate of resistance limited efficacy, particularly in patients who remained HBeAg positive on therapy.

Efficacy and safety of troglitazone in the treatment of lipodystrophy syndromes

BACKGROUND

Troglitazone promotes adipocyte differentiation in vitro and increases insulin sensitivity in vivo. Therefore, troglitazone may have therapeutic benefit in lipoatrophic diabetes.

OBJECTIVE

To determine whether troglitazone ameliorates hyperglycemia and hypertriglyceridemia or increases fat mass in lipoatrophic patients.

DESIGN

Open-labeled prospective study.

SETTING

United States and Canada.

PATIENTS

20 patients with various syndromes associated with lipoatrophy or lipodystrophy.

INTERVENTION

6 months of therapy with troglitazone, 200 to 600 mg/d.

MEASUREMENTS

Levels of hemoglobin A1c triglycerides, free fatty acids, and insulin; respiratory quotient; percentage of body fat; liver volume; and regional fat mass.

RESULTS

In the 13 patients with diabetes who completed 6 months of troglitazone therapy, hemoglobin A1c levels decreased by a mean of 2.8% (95% CI, 1.9% to 3.7%; P < 0.001). In all 19 study patients, fasting triglyceride levels decreased by 2.6 mmol/L (230 mg/dL) (CI, 0.7 to 4.5 mmol/L [62 to 398 mg/dL]; P = 0.019) and free fatty acid levels decreased by 325 micromol/L (CI, 135 to 515 micromol/L; P = 0.035). The respiratory quotient decreased by a mean of 0.12 (CI, 0.08 to 0.16; P < 0.001), suggesting that troglitazone promoted oxidation of fat. Body fat increased by a mean of 2.4 percentage points (CI, 1.3 to 4.5 percentage points; P = 0.044). Magnetic resonance imaging showed an increase in subcutaneous adipose tissue but not in visceral fat. In one patient, the serum alanine aminotransferase level increased eightfold during the 10th months of troglitazone treatment but normalized 3 months after discontinuation of treatment Liver biopsy revealed an eosinophilic infiltrate, suggesting hypersensitivity reaction as a cause of hepatotoxicity.

CONCLUSION

Troglitazone therapy improved metabolic control and increased body fat in patients with lipoatrophic diabetes. The substantial benefits of troglitazone must be balanced against the risk for hepatotoxicity, which can occur relatively late in the treatment course.

Resolution of chronic delta hepatitis after 12 years of interferon alfa therapy

Chronic delta hepatitis is an uncommon but severe form of chronic viral hepatitis for which there is currently no satisfactory therapy. A patient with chronic delta hepatitis was treated with interferon alfa, 5 million units daily for 12 years. Serial serum samples were tested for routine liver tests and selected samples for quantitative levels of hepatitis B surface antigen (HBsAg) and hepatitis delta virus RNA. Liver biopsies were performed before, during, and after an initial 1-year course of therapy and again after 3 and 10 years of continuous therapy. With initiation of interferon therapy, serum aminotransferase levels decreased to normal range, became abnormal again when the dose was reduced, and increased to pretreatment levels when therapy was stopped. With reinstitution and prolonged therapy, aminotransferase levels became persistently normal; after several years, both hepatitis delta virus RNA and serum HBsAg became undetectable. Liver biopsy, which initially revealed cirrhosis, showed gradual improvement in inflammatory and fibrosis scores and, after 10 years, no abnormalities or fibrosis. Therapy was stopped, and the patient remained free of evidence of infection. In conclusion, long-term therapy with interferon alfa in high doses led to resolution of chronic delta hepatitis, disappearance of hepatitis delta and B virus markers, and improvement in fibrosis.

Expression in transgenic mice of dominant interfering Fas mutations: a model for human autoimmune lymphoproliferative syndrome

Most humans with autoimmune lymphoproliferative syndrome (ALPS) carry heterozygous dominant mutations in one allele of the gene encoding Fas/APO-1/CD95. ALPS patients, like Fas-deficient MRL lpr/lpr mice, have lymphoproliferation, autoimmunity, increased CD4(-)/CD8(-) T lymphocytes, and apoptosis defects. Consistent with the phenotypic variability of lpr/lpr mice of different background strains, human genetic studies indicate that a Fas mutation is insufficient to induce ALPS in all mutation carriers. To investigate the dominant function of human Fas mutations and the additional genetic factor(s) involved in the development of ALPS, we generated transgenic mice expressing, in addition to endogenous Fas, mouse Fas molecules bearing mutations in the intracellular death domain corresponding to mutations identified in ALPS patients. Transgenic mice developed mild features of ALPS, including hepatosplenomegaly, elevated proportions of lymphocytes in spleen and lymph nodes, apoptotic defects, and hepatic lymphocytic infiltrates. Therefore defective murine Fas proteins act in a dominant manner to impair apoptosis of activated lymphocytes and disrupt lymphocyte homeostasis. The influence of genetic background on phenotype was studied by comparing transgenic mice on FVB/N and (FVB/N x MRL) backgrounds with syngenetic control mice and with MRL and MRL lpr/lpr mice. While expression of transgenic mutant Fas contributed mainly to hepatosplenomegaly and accumulation of lymphocytes, MRL background genes played a major role in the production of autoantibodies and elevated serum immunoglobulin levels. Moreover, compared to FVB/N (+/+) mice, a substantial Fas-specific apoptotic defect was found in MRL (+/+) mice, suggesting a mechanism for the known tendency of this strain to develop autoimmunity.

Lamivudine for chronic delta hepatitis

Chronic delta hepatitis is a severe form of chronic liver disease caused by hepatitis delta virus (HDV) infection superimposed on chronic hepatitis B or the hepatitis B surface antigen (HBsAg) carrier state. Therapy of delta hepatitis is currently unsatisfactory. We have evaluated lamivudine (3-thiacytidine), an oral nucleoside analogue with marked effects against hepatitis B, as therapy in 5 patients with chronic hepatitis D. Five men, ages 38 to 65 years, were treated. All had HBsAg, antibody to HDV, and HDV RNA in serum, as well as persistent elevations in alanine aminotransferase (ALT) levels and liver histology showing severe chronic hepatitis with fibrosis or cirrhosis. Lamivudine was given in a dose of 100 mg orally daily for 12 months. Patients were monitored carefully and tested for HBsAg, HBV-DNA and HDV-RNA levels serially during the year of treatment and for 6 months thereafter. Liver biopsies were performed before therapy and repeated after 1 year. Serum levels of HBV DNA fell rapidly in all 5 patients, becoming undetectable even by polymerase chain reaction (PCR) in 4. However, all 5 patients remained HBsAg- and HDV-RNA-positive, and serum ALT levels and liver histology did not improve. All patients tolerated therapy well. When lamivudine was stopped, HBV-DNA levels returned to pretreatment values without a change in disease activity. Lamivudine is a potent inhibitor of HBV-DNA replication, but does not improve disease activity or lower HDV-RNA levels in patients with chronic delta hepatitis.

Biophysical and functional characterization of full-length, recombinant human tissue inhibitor of metalloproteinases-2 (TIMP-2) produced in Escherichia coli. Comparison of wild type and amino-terminal alanine appended variant with implications for the mechanism of TIMP functions

Matrix metalloproteinases (MMPs) function in the remodeling of the extracellular matrix that is integral for many normal and pathological processes. The tissue inhibitor of metalloproteinases family, including tissue inhibitor of metalloproteinases-2 (TIMP-2), regulates the activity of these multifunctional metalloproteinases. TIMP family members are proteinase inhibitors that contain six conserved disulfide bonds, one involving an amino-terminal cysteine residue that is critical for MMP inhibitor activity. TIMP-2 has been expressed in Escherichia coli, folded from insoluble protein, and functionally characterized. The wild type protein inhibited gelatinase A (MMP-2), whereas a variant with an alanine appended to the amino terminus (Ala+TIMP-2) was inactive. Removal of amino-terminal alanine by exopeptidase digestion restored protease inhibitor activity. This confirms the mechanistic importance of the amino-terminal amino group in the metalloproteinase inhibitory activity, as originally suggested from the x-ray structure of a complex of MMP-3 with TIMP-1 and a complex of TIMP-2 with MT-1-MMP. The Ala+TIMP-2 variant exhibited conformational, pro-MMP-2 complex formation and fibroblast growth modulating properties of the wild type protein. These findings demonstrate that Ala+TIMP-2 is an excellent biochemical tool for examining the specific role of MMP inhibition in the multiple functions ascribed to TIMPs.

Matrix metalloproteinases and metastasis

Metastatic disease is responsible for the majority of cancer-related deaths, either directly due to tumor involvement of critical organs or indirectly due to complications of therapy to control tumor growth and spread. An understanding of the mechanisms of tumor cell invasion and metastasis may be important for devising therapies aimed at preventing tumor cell spread. Matrix metalloproteinases (MMPs) are a family of zinc-dependent endoproteinases whose enzymatic activity is directed against components of the extracellular matrix (ECM). In humans, 16 members of this family have been identified by cloning and sequencing. These proteinases are linked by a core of common domain structures and by their relationship to a family of proteinase inhibitors called the tissue inhibitors of metalloproteinases (TIMPs). Four members of the TIMP family have been cloned and sequenced in humans and they inhibit MMPs by forming tight-binding, noncovalent associations with the active site of the MMPs. MMPs facilitate tumor cell invasion and metastasis by at least three distinct mechanisms. First, proteinase action removes physical barriers to invasion through degradation of ECM macromolecules such as collagens, laminins, and proteoglycans. This has been demonstrated in vitro through the use of chemoinvasion assays and in vivo by the presence of active MMPs at the invasive front of tumors. Second, MMPs have the ability to modulate cell adhesion. For cells to move through the ECM, they must be able to form new cell-matrix and cell-cell attachments and break existing ones. Using a cell transfection system that altered the ratio of MMP-2 to TIMP-2 we have demonstrated significant variation in the adhesive phenotype of tumor cells. Finally, MMPs may act on ECM components or other proteins to uncover hidden biologic activities. For example, the angiogenesis inhibitor angiostatin may be produced from plasminogen by MMP action and laminin-5 is specifically degraded by MMP-2 to produce a soluble chemotactic fragment. Thus MMPs play multiple key roles in facilitating the metastasis of tumor cells. Therapies designed to interfere with specific MMP actions may be useful in the control of metastatic disease.

Melanoma-associated antigen recognized by T cells (MART-1): the advent of a preferred immunocytochemical antibody for the diagnosis of metastatic malignant melanoma with fine-needle aspiration

BACKGROUND

HMB-45, an antibody directed against a premelanosome glycoprotein, has thus far been considered the most specific antibody for the immunocytochemical substantiation of the diagnosis of malignant melanoma (MM). A recently described antigen, MART-1, is a transmembrane protein that is present in normal melanocytes and widely expressed in MM. Antibodies to MART-1 have recently become commercially available. Both HMB-45 and MART-1 form the basis of ongoing immunotherapy protocols at the National Institutes of Health/National Cancer Institute.

METHODS

The authors evaluated 207 lesions from 160 patients with metastatic MM procured via fine-needle aspiration (FNA) for expression of MART-1 (clone M2-7C10) and HMB-45 prior to commencement of immunotherapy. FNAs were performed on subcutaneous soft tissue masses (190 lesions), lung (8 lesions), liver (5 lesions), pancreas (3 lesions), and brain (1 lesion). To test the specificity of the monoclonal antibody directed against MART-1, the authors evaluated its reactivity in normal tissues as well as in various nonpigmented neoplasms that are often included in the differential diagnosis of MM.

RESULTS

Of all lesions tested, 13 (6%) were negative for both MART-1 and HMB-45. Of all patients tested, 20% had 1 or more lesions that were non-immunoreactive with HMB-45, whereas only 10% had 1 or more lesions that were nonimmunoreactive for MART-1. Eight percent of the lesions tested were negative for MART-1 only, whereas 16% of lesions tested were negative for HMB-45 only. In 35% of the lesions, MART-1 stained more cells than HMB-45. In 13%, MART-1 stained fewer cells than HMB-45, and in 52% both antibodies stained an equivalent number of cells. All samples of normal tissue were negative for staining with MART-1, as were the nonpigmented lesions tested. Melanocytes in normal skin samples stained positively for MART-1.

CONCLUSIONS

The MART-1 antibody is a superior immunohistochemical marker for the diagnosis of MM. It has the potential to become the preferred antibody over HMB-45 for the diagnosis of metastatic MM in FNA material, as MART-1 stains a higher percentage of lesions in a higher percentage of patients than does HMB-45.

10-Year follow-up after interferon-alpha therapy for chronic hepatitis C

Sustained responses to interferon-alpha occur in 10% to 25% of patients with chronic hepatitis C, but the long-term outcome is not well defined. We evaluated the long-term clinical, histological, and virological outcomes of 10 patients with chronic hepatitis C who were treated between 1984 and 1987 with interferon-alpha-2b for 52 +/- 6 weeks (total doses of 492 +/- 116 MU). Before therapy, all 10 had hepatitis C virus (HCV) RNA, elevations of serum aminotransferases, and chronic hepatitis with fibrosis on liver biopsy. Clinical follow up was 6 to 13 years, and liver biopsies were done 5 to 11 years after initiation of therapy. HCV RNA was assayed by qualitative and quantitative reverse transcriptase-polymerase chain reaction assays. Among 5 patients who had a 6-month sustained response after therapy, all remained HCV RNA negative, and at last follow-up, 4 had normal and 1 minimally elevated serum aminotransferase levels. Liver biopsy specimens were nonreactive for HCV RNA, and all the patients showed improvements in both inflammation and fibrosis and were either normal or had mild, nonspecific inflammatory changes. Among 5 patients without a sustained response, all continued to have HCV RNA in serum and persistent or intermittent aminotransferase elevations. Liver biopsy specimens showed little or no change in necrosis and inflammation; all except 1 patient had progression of fibrosis scores or cirrhosis. All 5 patients had symptoms of chronic hepatitis, 1 underwent liver transplantation, and another had progressive hepatic decompensation. In conclusion, patients with a 6-month posttreatment virological response have a favorable long-term clinical and histological outcome.

Pruritus as a presenting symptom of chronic hepatitis C

Pruritus is a common symptom in cholestatic liver disease but is rare in chronic hepatitis C. Eight patients with chronic hepatitis C and severe pruritus were compared with regard to biochemical, serological, and histological features to eight disease controls with primary biliary cirrhosis and seven with cirrhosis due to hepatitis C. Among those with severe pruritus associated with chronic hepatitis C, serum aminotransferases were raised in all, alkaline phosphatase in four, and gamma-glutamyl-transpeptidase levels in all except one. Serum cholylglycine levels were elevated in seven of eight patients. Liver biopsies showed moderate to severe fibrosis in all patients and cirrhosis in five. Compared to control subjects with cirrhosis due to hepatitis C but no pruritus, ductopenia, and cholestatic changes were prominent, although less so than in controls with primary biliary cirrhosis. Chronic hepatitis C with moderate to severe fibrosis may result in low-grade cholestasis with pruritus, possibly in association with bile duct disappearance.

Polypoid lesions of airways: early experience with computer-assisted detection by using virtual bronchoscopy and surface curvature

PURPOSE

To test the application of a technique developed by the authors for the computer-assisted diagnosis of polypoid airway lesions from surface rendered virtual bronchoscopic reconstructions.

MATERIALS AND METHODS

A computer algorithm was developed to detect polypoid airway lesions by means of segmentation of the bronchial surface with curvature classification. This method was tested with a bronchial phantom, five cadaveric lung specimens, and virtual bronchoscopic studies in 16 patients.

RESULTS

For the patient studies, the sensitivity and specificity of the method were 47%-88% and 58%-89%, respectively, depending on the value of an adjustable parameter (the mean curvature threshold). The sensitivity increased (by 20% to 34%) when only lesions larger than 5 mm in diameter were considered.

CONCLUSION

With this method, polypoid airway lesions can be detected automatically, although false-positive diagnoses present an important limitation.

Chemically modified tetracyclines inhibit human melanoma cell invasion and metastasis

Recent work has shown that chemically modified tetracyclines (CMTs) are potent inhibitors of matrix metalloproteinase (MMP) activity, both in vitro and in vivo, which is distinct from their antimicrobial activities (Golub et al. Crit Rev Oral Biol Med, 2, 297-321, 1991; Ryan et al. Curr Opin Rheumatol, 8, 23847, 1996). The process of tumor cell invasion requires MMP-mediated degradation of extracellular matrix barriers as a key step in the metastasic cascade. In this study, we examined the effect(s) of doxycycline and CMTs on extracellular levels of gelatinase A and B activity from a highly invasive and metastatic human melanoma cell line C8161, and correlated these observations with changes in the cells' biological behavior in an in vitro invasion assay and in an in vivo SCID mouse model. The results indicate that coincident with the ability of these compounds to differentially suppress extracellular levels of gelatinase activity, C8161 cells treated with doxycycline, CMT-1, CMT-3, or CMT-6 were less invasive in vitro in a dose-dependent manner (3-50 microg/ml). Furthermore, data derived from the in vivo model indicate that SCID mice dosed orally with CMT-1 or CMT-3 contained a reduced number of lung metastases following i.v. injection of C8161 cells via tail vein inoculation. These observations suggest that careful screening of different CMTs could lead to the identification of compounds which suppress the formation and magnitude of metastases associated with certain cancers, and if used as an adjunct to other treatment regimes, lead to greater efficacy in the treatment of metastatic cancers.

Long-term follow-up of patients with chronic hepatitis B treated with interferon alfa

BACKGROUND & AIMS

Therapy with interferon alfa (IFN-alpha) leads to remission of disease in one third of patients with chronic hepatitis B. The aim of this study was to better define the long-term prognosis of this outcome.

METHODS

One hundred three patients with chronic hepatitis B who underwent IFN-alpha therapy in three clinical trials between 1984 and 1991 were followed up for serological status, biochemical evidence of liver disease, and liver complications or mortality through 1994.

RESULTS

Among 103 patients, 31 (30%) responded to therapy with loss of hepatitis B e antigen and viral DNA from serum. Responders were more likely than nonresponders to be women, black, and to have more severe liver disease including cirrhosis (P < 0.05). Up to 11 years (mean, 6.2 years) after therapy, a higher percentage of responders than nonresponders were still negative for hepatitis B e antigen (94% vs. 40%; P < 0.001) and hepatitis B surface antigen (71% vs 8.3%; P < 0.001). Overall, the rate of liver-related complications and death did not differ by IFN-alpha response, but with adjustment for cirrhosis, nonresponders had higher rates of liver-related complications and mortality (hazard ratio, 13.7; 95% confidence interval, 3.0-63.5).

CONCLUSIONS

The response to IFN-alpha therapy in chronic hepatitis B is usually a sustained improvement in disease markers and, when cirrhosis is considered, patient outcome.

Assessment of monoethylglycinexylidide as measure of liver function for patients with chronic viral hepatitis

The liver metabolizes lidocaine by oxidative deethylation to form monoethylglycinexylidide (MEGX), an analyte proposed as an index of liver function. We determined MEGX and lidocaine serum concentrations with the TDx (Abbott Laboratories) at baseline and 15, 30, 60, and 90 min after the intravenous administration of lidocaine (1 mg/kg), analyzing specimens from 12 apparently healthy volunteers and 40 patients with chronic viral hepatitis diagnosed by liver biopsy and serum tests. The patients were grouped on the basis of the histology activity index. The following laboratory tests were performed on serum specimens from all subjects: albumin (ALB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, total bilirubin, and prothrombin time. The results showed no significant difference among the four groups for the concentrations of MEGX, lidocaine, and lidocaine/MEGX at the four time points. However, the concentrations of ALB, ALT, AST, AST/ALT, and prothrombin time were substantially different among the four groups. Thus, we conclude that assay of MEGX in our patients with chronic viral hepatitis did not contribute to the assessment of liver function when compared with apparently healthy volunteers and traditional tests of liver function.

Assessment of monoethylglycinexylidide as measure of liver function for patients with chronic viral hepatitis

The liver metabolizes lidocaine by oxidative deethylation to form monoethylglycinexylidide (MEGX), an analyte proposed as an index of liver function. We determined MEGX and lidocaine serum concentrations with the TDx (Abbott Laboratories) at baseline and 15, 30, 60, and 90 min after the intravenous administration of lidocaine (1 mg/kg), analyzing specimens from 12 apparently healthy volunteers and 40 patients with chronic viral hepatitis diagnosed by liver biopsy and serum tests. The patients were grouped on the basis of the histology activity index. The following laboratory tests were performed on serum specimens from all subjects: albumin (ALB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, total bilirubin, and prothrombin time. The results showed no significant difference among the four groups for the concentrations of MEGX, lidocaine, and lidocaine/MEGX at the four time points. However, the concentrations of ALB, ALT, AST, AST/ALT, and prothrombin time were substantially different among the four groups. Thus, we conclude that assay of MEGX in our patients with chronic viral hepatitis did not contribute to the assessment of liver function when compared with apparently healthy volunteers and traditional tests of liver function.

Progelatinase A mRNA expression in cell lines derived from tumors in patients with metastatic renal cell carcinoma correlates inversely with survival

OBJECTIVES

Tumors are thought to metastasize by a process involving tumor cell attachment to extracellular matrix, degradation of matrix components by tumor-associated proteases, and cellular movement into the area modified by protease activity. Type IV collagen comprises the major element tumor cells must degrade to gain access to the rest of the body. Renal cancer cell line progelatinase A (E.C. 3.4.24.24; 72-kDa type IV collagenase; MMP-2) mRNA expression was correlated with patient survival.

METHODS

Total cellular mRNA was extracted from tumor cell lines derived from patients with metastatic renal cell carcinoma. The results of the densitometric analysis of Northern blots were correlated with patient survival. Formalin-fixed, paraffin-embedded tissue sections of primary renal cancers were examined for immunohistochemical expression of MMP-2.

RESULTS

Cell lines established from 23 primary renal tumors and six metastatic sites in 26 patients with metastatic renal carcinoma were studied. Variable expression of progelatinase A, relative to A2058 melanoma cells (mean +/- SEM, 0.60 +/- 0.21; median, 0.082; range, 0 to 4.78), was found. There was a significant inverse association between patient survival and the log of the MMP-2 expression (P = 0.045 by the Cox proportional-hazards model). Using a cutoff value of 0.10, the closest round number to the median expression of MMP-2, a significant difference between survival of patients with lower and higher MMP-2 expression in their primary renal cell line was found (P = 0.0054). Cell lines with low, intermediate, and high expression of MMP-2 mRNA all had primary tumors with high tissue immunohistochemical expression of MMP-2.

CONCLUSIONS

These studies demonstrate an inverse relationship between renal cancer cell line MMP-2 mRNA expression and patient survival. Immunohistochemical studies of the primary tumors from which the cell lines were derived uniformly showed high MMP-2 expression. Previous work suggests local renal factors upregulate cellular expression of MMP-2 in the primary tumor, and are not active at extrarenal sites.

Adrenocortical neoplasms: role of prognostic markers MIB-1, P53, and RB

Differentiation between benign and malignant adrenocortical neoplasms is made using a combination of clinical and pathologic parameters. Despite these parameters, it is still difficult to predict the biologic potential of some tumors. Forty adrenocortical lesions, including 10 hyperplasias, 10 adenomas, 12 carcinomas and eight metastatic/recurrent adrenocortical carcinomas were studied for the expression of MiB-1, p53, and the retinoblastoma gene product (RB) utilizing immunohistochemical techniques. The mean tumor proliferating fraction (TPF), expressed as the number of MiB-1-positive nuclei per 1,000 tumor cells, was 14.9 in adenomas, 31.5 in hyperplasias, 208.1 in carcinomas and 166.1 in recurrent or metastatic disease. None of the 20 benign lesions had a TPF of > 80, and only one of the 20 malignancies had a TPF of < 80. Nine of the 20 carcinomas were positive for p53. None of the benign lesions were p53 positive. Thirty-nine cases, including benign and malignant ones, were RB positive, and one was uninterpretable. We conclude that prognostic markers can be of great assistance in recognizing adrenocortical carcinomas. High TPF (> 80), as measured by staining with MiB-1, and positive p53 strongly correlate with malignant behavior and therefore may be useful in distinguishing benign from malignant adrenal lesions. Staining for RB does not appear to be a helpful technique.

Histopathologic changes associated with fialuridine hepatotoxicity

Chronic hepatitis B is a widespread viral illness with the serious sequelae of cirrhosis and hepatocellular carcinoma. Current therapy with interferon is not universally efficacious, and this has led to the evaluation of other antiviral agents. A recent Phase II trial of the nucleoside analogue, fluoroiodoarabinofuranosyluracil (fialuridine, FIAU) was halted because of the sudden development of severe multisystem toxicity characterized by hepatic failure, lactic acidosis, and pancreatitis, which resulted in the deaths of five patients. We systematically evaluated pre- and post-therapy biopsy, explant, and autopsy specimens from the 15 patients involved in this trial to define the hepatic changes of fialuridine toxicity and to determine whether the degree of pre-existing hepatitis contributed to the severity of toxicity. Severe hepatotoxicity from fialuridine was characterized by hepatomegaly with diffuse, predominantly microvesicular steatosis, hepatocellular glycogen depletion, marked bile ductular proliferation, and cholestasis. Ultrastructural examination revealed intracytoplasmic lipid droplets and marked mitochondrial injury. Patients in whom severe toxicity did not develop mainly showed changes caused by the underlying chronic hepatitis B alone. There was a subtle increase in the amount of microvesicular steatosis in two of six patients with mild or no symptoms of toxicity. The microscopic and ultrastructural pattern of injury and systemic symptoms in patients with fialuridine toxicity are consistent with severe mitochondrial and metabolic derangements. Similar hepatic pathologic findings have been reported rarely for other antiviral nucleoside analogues, which suggests that the mechanisms of toxicity might be related.

The role of prognostic markers (MiB-1, RB, and bcl-2) in the diagnosis of parathyroid tumors

Assessment of the malignant potential of parathyroid tumors in the absence of metastasis can be difficult using morphologic criteria alone. The role of prognostic markers that may assist in evaluating aggressive behavior in these tumors has not been fully studied. We performed a retrospective study of 31 parathyroid lesions, including 10 adenomas, 10 atypical lesions, and 11 carcinomas, to evaluate the diagnostic and prognostic role of the MiB-1, p53, RB, and bcl-2 markers by immunohistochemical techniques. The mean tumor proliferative fraction (TPF), expressed as the number of MiB-1-positive nuclei per 1000 cells, was 20.3 in adenomas (range, 5-51), 20.0 in atypical lesions (range, 8-36), and 79.8 in carcinomas (range, 4-133). Only 1 of 20 benign lesions had a TPF more than 40, and only 2 of 11 carcinomas had a TPF less than 40. One atypical lesion and two carcinomas showed scattered cells positive for p53. Patients with the adenoma with increased TPF and the atypical lesion with positive p53 have been free of disease for 16 months. bcl-2 was expressed in 7 (70%) of 10 adenomas, 2 (20%) of 10 atypical lesions, and 4 (36%) of 11 carcinomas. Two of the 11 carcinomas were RB negative, whereas all of the 20 benign lesions were RB positive. We conclude that high TPF (greater than 40 as measured by staining with MiB-1) strongly correlates with malignancy and, therefore, may be useful in the diagnosis of carcinomas. Negative RB stain, although not a common event, may be helpful to exclude benign lesions. Other tumor markers (p53 and bcl-2) were not useful in distinguishing malignant from benign lesions.

Quantitative reverse zymography: analysis of picogram amounts of metalloproteinase inhibitors using gelatinase A and B reverse zymograms

Matrix metalloproteinases are a growing family of neutral pH optima, zinc atom-dependent endopeptidases that collectively degrade all components of the extracellular matrix. This family of related proteases is further defined by their inhibition of protease activity by a class of low-molecular-weight endogenous inhibitors known as tissue inhibitors of metalloproteinases or TIMPs. Reverse zymography is an electrophoretic technique used to identify TIMP inhibitory activity within acrylamide gels. Previous methods have generally used biochemically complex sources of proteolytic activity (such as cell culture conditioned media) copolymerized with a proteinase substrate in the gel to identify the zones of inhibited proteolysis. We describe a novel system for reverse zymography using purified recombinant human gelatinase A or gelatinase B in place of conditioned media. These reverse zymograms using recombinant gelatinase have sensitivities for TIMPs that are favorable in comparison to immunoblotting techniques but have the benefit of visualizing multiple inhibitors simultaneously. We have developed and characterized these methods for the evaluation of inhibitors and have shown them to be highly sensitive, convenient, and reproducible. Both systems detect TIMPs 1, 2, and 3 simultaneously, but with differential sensitivities for TIMPs 1 and 2. Using gelatinase A the system can detect as little as 1 pg of rTIMP-2, but the limit of detection for rTIMP-1 is 40 pg. Gelatinase B shows less differential activity in that the limits of detection are 60 and 40 pg for TIMP-2 and TIMP-1, respectively. We demonstrate how these varied sensitivities of the gelatinases for the TIMPs can contribute to potential pitfalls in systems using uncharacterized reagents (i.e., conditioned media).

Perirenal myelolipoma

Extra-adrenal myelolipomas are rare, benign tumors composed of hematopoietic and adipose elements. Although these tumors can cause local symptoms or hemorrhage, they are generally asymptomatic. However, when discovered intraoperatively, they pose a diagnostic dilemma to the urologic surgeon. We present a case of perirenal extra-adrenal myelolipoma discovered intraoperatively in a patient with von Hippel-Lindau disease undergoing partial nephrectomy.

Pilot study of low dose oral methotrexate treatment for primary biliary cirrhosis

OBJECTIVE

To assess the efficacy of low doses of oral methotrexate as therapy for primary biliary cirrhosis.

METHODS

Ten symptomatic patients with this disease were treated with methotrexate at a dose of 15 mg/wk in an open label trial.

RESULTS

Eight patients completed 1 yr of treatment and six completed 2. Pruritus and fatigue decreased in all patients treated for at least 1 yr. Mean levels of serum alkaline phosphatase, ALT, and IgM were less at 1 and 2 yr than corresponding baseline means. Total serum bilirubin increased in three patients during treatment. Serum aminotransferases and alkaline phosphatase became normal in one patient with stage I disease. Although liver biopsies at 1 and 2 yr revealed a decrease in the intensity of the inflammatory infiltrate, they also showed an increase in fibrosis suggestive of disease progression. Methotrexate was discontinued in five patients: for disease progression in four (one at 4 months, one at 1 yr, and two at 2 yr) and for intractable pruritus in one (at 4 months). All patients experienced transient mucositis and intermittent dyspepsia.

CONCLUSIONS

These findings suggest that methotrexate treatment in patients with primary biliary cirrhosis is not beneficial in patients with advanced disease; in patients with early disease, methotrexate may be associated with amelioration of symptoms, reduction in serum biochemical indices of liver disease, and reduction in hepatic inflammation. However, prospective, randomized controlled trials will be necessary for definitive evaluation of the effects of methotrexate on the quality of life and survival of patients with primary biliary cirrhosis.

MMP-2: expression, activation and inhibition

Remodeling of the extracellular matrix (ECM), which occurs during many physiological and pathological processes, is one of the requisite events of cellular invasion. The matrix metalloproteinases (MMPs) are a family of zinc-dependent proteases that are responsible for proteolytic degradation of specific ECM components. Regulating the activity of the MMPs at both mRNA and/or protein levels modulates the degradation of the ECM components which in turn alter cellular invasion. Although most MMPs are regulated via similar mechanisms at the mRNA and protein levels, the modulation of gelatinase A is unique. Understanding the mechanisms that regulate gelatinase A is important since expression and activation of this particular MMP is consistently correlated with a majority of malignant phenotypes. In this report, we will contrast the mechanisms that regulate the expression, activation and inhibition of gelatinase A with the mechanisms that modulate the rest the MMP family.

Molecular regulation of cellular invasion--role of gelatinase A and TIMP-2

Extracellular matrix (ECM) turnover is an event that is tightly regulated. Much of the coordinate (physiological) or discoordinate (pathological) degradation of the ECM is catalyzed by a class of proteases known as the matrix metalloproteinases (MMPs) or matrixins. Matrixins are a family of homologous Zn atom dependent endopeptidases that are usually secreted from cells as inactive zymogens. Net degradative activity in the extracellular environment is regulated by specific activators and inhibitors. One member of the matrixin family, gelatinase A, is regulated differently from other MMPs, suggesting that it may play a unique role in cell-matrix interactions, including cell invasion. The conversion from the 72 kDa progelatinase A to the active 62 kDa species may be a key event in the acquisition of invasive potential. This discussion reviews some recent findings on the cellular mechanisms involved in progelatinase A activation and, in particular, the role of tissue inhibitor of matrix metalloproteinases-2 (TIMP-2) and transmembrane containing metalloproteinases (MT-MMP) in this process.

Ribavirin as therapy for chronic hepatitis C. A randomized, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate ribavirin, an oral antiviral agent, as therapy for chronic hepatitis C.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

Clinical Center of the National Institutes of Health, a tertiary referral research hospital.

PATIENTS

29 patients with chronic hepatitis C who received oral ribavirin (600 mg twice daily) for 12 months and 29 controls with chronic hepatitis C who received placebo for 12 months.

MEASUREMENTS

Effects of therapy were evaluated by measuring serum aminotransferase and hepatitis C virus (HCV) RNA levels before, during, and for 6 months after therapy and by histologic examination of liver specimens before and at the end of treatment.

RESULTS

Patients treated with ribavirin had a prompt decrease in serum aminotransferase levels (54% overall) compared with levels before treatment and levels in controls (5% decrease). Serum aminotransferase levels became normal or nearly normal in 10 patients treated with ribavirin (35% [95% CI, 18% to 54%]) but in no controls (0% [CI, 0% to 12%]). Aminotransferase levels remained normal in only 2 patients after ribavirin therapy was discontinued (7% [CI, 1% to 23%]). Serum HCV RNA levels did not change during or after therapy. Liver biopsy specimens showed a decrease in hepatic inflammation and necrosis among ribavirin-treated patients whose aminotransferase levels became normal.

CONCLUSIONS

Ribavirin has beneficial effects on serum aminotransferase levels and histologic findings in the liver in patients with chronic hepatitis C, but these effects are not accompanied by changes in HCV RNA levels and are not sustained when ribavirin therapy is discontinued. Thus, ribavirin alone for periods as long as 12 months is unlikely to be of value as therapy for chronic hepatitis C.

Hepatic involvement in mastocytosis: clinicopathologic correlations in 41 cases

Mastocytosis is a disease of mast cell hyperplasia that may involve several organ systems, including liver. Between 1988 and 1991, we conducted a retrospective-prospective study of 41 patients with mastocytosis and found 61% had evidence of liver disease. Hepatomegaly was detected in 24%, splenomegaly in 41%, and elevated serum alkaline phosphatase, serum aminotransaminases, 5'nucleotidase, or gamma-glutamyltranspeptidase (GGTP) in 54% of the patients. Alkaline phosphatase levels directly correlated with GGTP levels, hepatomegaly, splenomegaly, and liver mast cell infiltration and fibrosis. Elevated alkaline phosphatase levels and splenomegaly were observed more frequently in patients with categories II and III mastocytosis. Five patients in combined disease categories II or III developed ascites or portal hypertension and died of complications of mastocytosis; three had hypoprothrombinemia at the time of death. Thirty-five liver biopsy specimens from 25 patients were examined. Mast cell infiltration was commonly observed in the biopsy specimens, more severe in those patients with either category II or III disease, and correlated with hepatomegaly, splenomegaly, alkaline phosphatase levels, and GGTP levels. Mast cells were often only detected by using special stains (toluidine blue and chloracetate esterase). Increased portal fibrosis was seen in 68% of the biopsy specimens and correlated with mast cell infiltration and portal inflammation. Cirrhosis was not observed. Nodular regenerative hyperplasia, portal venopathy, and venoocclusive disease was observed in eight biopsy specimens and may have been the cause of the portal hypertension or ascites in four patients. These findings demonstrate that liver disease with mast cell infiltration is a common finding in patients with mastocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of transforming growth factor alpha in the liver before and after interferon alfa therapy for chronic hepatitis B

The effect of interferon alfa (IFN-alpha) therapy on the expression of transforming growth factor alpha (TGF-alpha) in the liver during chronic hepatitis B was investigated. Serial liver biopsy specimens were evaluated from 35 patients who had participated in a randomized, controlled trial of recombinant human IFN-alpha for the treatment of chronic hepatitis B. Percutaneous liver biopsy specimens obtained before and 1 year after entry in the trial were sectioned and stained with a monoclonal antibody to TGF-alpha in an avidin-biotin-peroxidase-complex system. The expression of TGF-alpha in each section was evaluated blindly (with respect to treatment group and order of biopsies) and was numerically scored. There was no significant difference in TGF-alpha expression before or after therapy between 13 patients receiving daily IFN-alpha, 13 receiving alternate-day IFN-alpha, and 9 receiving no therapy. Sustained clearance of HBV-DNA and DNA polymerase activity occurred in 8 of 26 treated patients ("responders"); the 18 other patients were "nonresponders." Expression of TGF-alpha before IFN-alpha therapy was significantly higher in responders than in nonresponders; after IFN-alpha therapy, TGF-alpha expression decreased significantly among responders compared with nonresponders and untreated controls. Thus, the level of expression of TGF-alpha in the liver, which was correlated with the severity of inflammation in the liver in this study, appeared to be predictive of the response to IFN-alpha therapy in chronic hepatitis B, with a higher level of expression indicating a greater likelihood that the patient would respond.

Volunteer blood donors with antibody to hepatitis C virus: clinical, biochemical, virologic, and histologic features. The Hepatitis C Study Group

OBJECTIVE

To assess the clinical significance of antibody to hepatitis C virus (anti-HCV) in volunteer blood donors.

DESIGN

Prospective cohort study.

SETTING

National Institutes of Health Clinical Center, a tertiary referral research hospital.

PATIENTS

60 anti-HCV-positive blood donors, divided into three groups of 20 persons each: Group I had normal alanine aminotransferase levels, group II had levels elevated to values less than twice the normal range, and group III had levels elevated to values greater than twice the normal range.

MEASUREMENTS

Medical history, results of laboratory and virologic testing, and percutaneous liver biopsy findings.

RESULTS

Participants with normal alanine aminotransferase levels were older and more often female than those with abnormal levels. The source of infection, duration of disease, symptom score, and amount of alcohol consumed were similar in the three groups. Hepatitis C virus RNA was detectable in 85% of participants, more commonly in the groups with elevated alanine aminotransferase levels (95%) than in the group with normal levels (65%); however, titers were similar in all groups. Examination of liver biopsy specimens showed chronic hepatitis in 54 participants (90%) and cirrhosis in 1 participant. The only normal liver biopsy specimens (n = 3) were those from participants who were HCV RNA negative and had normal alanine aminotransferase levels.

CONCLUSIONS

Most blood donors with anti-HCV have chronic hepatitis C regardless of their serum alanine aminotransferase levels. Donors with normal alanine aminotransferase levels and no HCV RNA in their serum generally have normal liver histologic findings or minimal changes and have probably recovered from HCV infection.

Increased human immunodeficiency virus (HIV) type 1 DNA content and quinolinic acid concentration in brain tissues from patients with HIV encephalopathy

Levels of human immunodeficiency virus type 1 (HIV-1) DNA and quinolinic acid were examined in areas of the central nervous system (CNS) and lymphoid organs (LN) from 5 AIDS patients with no clinically apparent CNS compromise (group I), 7 with CNS opportunistic diseases (group II), and 8 with HIV encephalopathy (group III). The brains from patients with HIV encephalopathy not only contained higher levels of HIV-1 DNA (cerebrum, P < .01; cerebellum, P < .05) as assessed by quantitative polymerase chain reaction but also showed a higher rate of viral pol region mutations suggestive of zidovudine or didanosine resistance than brains from patients in group I or II (P < .01). CNS quinolinic acid concentrations were significantly higher in group II and III patients than in group I (P = .03), even though quinolinic acid levels in LN were comparable among the 3 groups. These data suggest that CNS inflammatory changes associated with HIV encephalopathy may be triggered by a local productive HIV-1 infection within the CNS.

Cholestasis is associated with preproenkephalin mRNA expression in the adult rat liver

Cholestatic liver disease is associated with clinical and experimental findings consistent with increased opioidergic neuromodulation, increased plasma total opioid activity, and elevated plasma enkephalin concentrations. In contrast to the normal adult rat liver, preproenkephalin mRNA was detected by Northern blotting in livers of adult rats with cholestasis due to bile duct resection and not in the sham-resected controls. Preprodynorphin mRNA was not detected in livers of either group, while preproopiomelanocortin mRNA was found in very low levels in both groups. Preproenkephalin mRNA was not expressed in the livers of rats with acute hepatocellular necrosis induced by thioacetamide. Hybridization histochemistry of cholestatic livers demonstrated the presence of preproenkephalin mRNA primarily over cells in the periportal areas, some of which appeared to be proliferating bile ductular cells. Immunohistochemical staining of cholestatic liver indicated the production of at least Met-enkephalin in association with preproenkephalin gene expression. These findings suggest that the liver itself, by synthesizing enkephalins, contributes directly to the abnormalities of the opioid system reported in cholestasis.

Increase in hepatic iron stores following prolonged therapy with ribavirin in patients with chronic hepatitis C

Ribavirin, an oral nucleoside analogue being evaluated as therapy for chronic hepatitis C, is associated with hemolysis. Other hemolytic conditions are known to be associated with accumulation of iron within the liver. We therefore examined hepatic iron stores before and after 6 to 12 months of therapy with ribavirin in 15 patients with chronic hepatitis C. Although there were no significant changes in serum iron or ferritin levels, hepatic iron staining increased in almost all patients. Using a ranking system to quantitate the amount of hepatic iron staining, we found that the mean rank increased from 3.9 to 8.5 after therapy (p < 0.01). In six patients in whom hepatic tissue was available for determination of hepatic iron, concentrations also increased in all cases from a mean of 826 to 1857 micrograms/g dry weight (p < 0.01). The average rate of iron accumulation in these six patients was approximately 1500 micrograms/g per year. Thus hepatic iron concentrations might enter the range clearly associated with hepatic fibrosis after approximately 15 years of continuous therapy.

Galectin-3 is a novel substrate for human matrix metalloproteinases-2 and -9

The primary structure of galectin-3, a approximately 30 kDa galactoside-binding protein (aka CBP-35, mL-34, hL-31, L-29, Mac-2, and epsilon BP), reveals two structural domains: an amino-terminal domain consists of a Pro-Gly-rich motif, and a globular carboxyl-terminal domain containing a carbohydrate-binding site. In this study, we report that the amino-terminal domain of galectin-3 contains a cleavage site for two members of the matrix metalloproteinase family of enzymes: the 72 kDa (gelatinase A, MMP-2) and the 92 kDa (gelatinase B, MMP-9) proteinases. The major cleavage site for the gelatinases in galectin-3 is at the Ala62-Tyr63 bond, and its hydrolysis by these enzymes was inhibited by TIMP-2. Cell-surface expression of galectin-3 was reduced following treatment of viable T47D human breast carcinoma cells with gelatinase A. These results suggest that galectin-3 may be a substrate for gelatinases and that its degradation may play a role in modulating the biological activities of galectin-3.

RB tumor suppressor gene expression in hepatocellular carcinomas from patients infected with the hepatitis B virus

Hepatitis B virus (HBV) infection is closely associated with the development of hepatocellular carcinoma (HCC), but definite mechanisms by which it could play an etiologic role have not yet been identified. Modifications of the function of the RB tumor suppressor gene, which regulates the cell cycle, could provide such a mechanism. In the present study, the expression of the protein product of RB, pRB, was evaluated by immunohistochemical staining in HCC tissues from 25 patients from China and the United States, adjacent nontumorous liver from 19 of those patients, five human HCC cell lines, three human hepatoblastoma cell lines, and five specimens of normal human liver. Representative samples were also evaluated by western blot. Altered expression of RB was detected in eight HCC tissues (pRB undetectable in five HCCs and detected in < 1% of nuclei of HCC cells in three others); all eight had detectable hepatitis B surface or core antigen in the adjacent nontumorous liver, indicating active HBV infection. pRB was detected in 10-95% of nuclei (normal expression) in the remaining 17 HCCs, and in many nuclei in all 19 nontumorous livers, and in the 5 normal livers. No pRB staining was detected in the nuclei of three HCC cell lines, but pRB was detected in > 90% of nuclei of the other HCC and hepatoblastoma cell lines. The relationship of pRB expression to mutations of the p53 tumor suppressor gene was also examined. The absence of detectable nuclear pRB by immunohistochemical staining was associated with the presence of presumed mutant p53 detected by immunohistochemical staining in four out of five HCC cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative analysis of viral burden in tissues from adults and children with symptomatic human immunodeficiency virus type 1 infection assessed by polymerase chain reaction

The amount of human immunodeficiency virus type 1 (HIV-1) in various tissues was investigated by polymerase chain reaction (PCR) in 16 patients with end-stage HIV-1 infection and 7 patients with symptomatic but less advanced disease. During postmortem study of the 16 end-stage patients, HIV-1 DNA was found most often in lymph nodes and the spleen (both 100%), lung (93.8%), and colon (87.5%). Biopsied lymph nodes from the 7 symptomatic patients contained substantially higher copy numbers of HIV-1 RNA and DNA than did peripheral blood mononuclear cells (PBMC). Plasma viral RNA levels correlated significantly with the amount of HIV-1 RNA in PBMC (r2 = .86, P = .0025) but not with the level of viral RNA in lymph nodes in patients with symptomatic HIV-1 infection. These data suggest that although lymph nodes represent the main site for HIV-1 infection and replication, the level of circulating viral burden may not be solely determined by the magnitude of active HIV-1 replication in lymph nodes.

Quantitative zymography: detection of picogram quantities of gelatinases

Zymography is an electrophoretic technique used to identify proteolytic activity in enzymes separated in polyacrylamide gels under nonreducing conditions. It has been used extensively in the qualitative evaluation of proteases present in tumors and cell culture conditioned media. Using commercially available precast gels and a modern image analysis system, we have evaluated zymography as a quantitative technique. The degree of digestion of gelatin within the zymogram by purified gelatinase A, a matrix metalloprotease, is directly proportional to the amount of enzyme loaded over a 10- to 20-fold range. With an overnight (18 h) digestion period, the linear range of this assay extended from 10 to 120 pg of enzyme. The initial rate of digestion is proportional to the enzyme loading and varying the incubation time results in a shift in the linear range of the assay. Active and latent forms of gelatinase A show the same degree of digestion in this assay system. These results justify the use of zymography in the quantitative assessment of gelatinase activity as well as demonstrate its usefulness as a qualitative technique for the analysis of gelatinase species present.

Extracellular matrix 6: role of matrix metalloproteinases in tumor invasion and metastasis

Tumor invasion and metastasis formation are major obstacles for successful cancer therapy. Metastasis is a complex multistep process that requires sequential interactions between the invasive cell and the extracellular matrix. A model system for tumor invasion of extracellular matrix barriers has been developed, and application of this model has facilitated our understanding of the molecular mechanisms of metastasis formation. This model consists of three steps: tumor cell adhesion, extracellular matrix proteolysis, and cell migration. The role of the matrix metalloprotease enzymes in tumor cell-mediated extracellular matrix proteolysis is well established. We review the functional domain structure of the matrix metalloprotease enzymes in general and specifically the interaction of metastasis-associated gelatinase A (72-kDa type IV collagenase) with the tissue inhibitor of metalloproteases-2 (TIMP-2). We also discuss the physiologic activation of the matrix metalloprotease enzymes and the specific cellular mechanism of action of gelatinase A.

Structural biochemistry and activation of matrix metalloproteases

The degradation of the extracellular matrix is part of many pathological and physiological processes. Of the several proteases involved in extracellular matrix turnover, the plasmin/plasminogen activator system and the family of matrix metalloproteases have received the most attention. Recent investigations in the field of matrix metalloprotease biochemistry have focused on the functions of the various enzyme domains and their interactions with inhibitor domains. Research into physiological activation mechanisms has demonstrated a plasmin/plasminogen activator-metalloprotease cascade, as well as providing an initial characterization of cell surface associated metalloprotease activation.

Stability analysis of latent and active 72-kDa type IV collagenase: the role of tissue inhibitor of metalloproteinases-2 (TIMP-2)

The degradation of extracellular matrix is an important facet of many physiological and pathological processes. The collagenases form a family of matrix degradative enzymes that have similar active site sequences and activation mechanisms and are inhibited by a specific class of proteinase inhibitors referred to as tissue inhibitors of metalloproteinases. Regulation of enzyme activity is a complex process involving control at multiple levels: message transcription and translation, activation of latent proenzymes, inhibition of activity by specific inhibitors, and degradation of activated enzymes. We have examined the role of the proteinase inhibitor tissue inhibitor of metalloproteinases-2 (TIMP-2) on two of these processes: the autoactivation and autodegradation of the human 72-kDa type IV collagenase. We compared the stability of the enzyme in these two processes using three different enzyme preparations: the enzyme-inhibitor complex as isolated from human A2058 melanoma cells, recombinant enzyme free of TIMP-2, and enzyme separated from TIMP-2 by acid denaturation. We have found little evidence to support the hypothesis that the enzyme is able to autoactive, as no autoactivation occurs in the presence of TIMP-2 and only 20% autoactivation occurs in its absence, and then only after 24 h of incubation at 37 degrees C. However, TIMP-2 does appear to inhibit autodegradation, possibly by a mechanism distinct from its ability to inhibit substrate proteolysis. Enzyme isolated via chromatography involving acid mobile phases produces a mixture of cleavage products that is mostly denatured, inactive enzyme fragments. The role of TIMP-2 as an inhibitor of autodegradation suggests that the enzyme may show two physiological phenotypes: the free enzyme having a high level of activity and rapid autodegradation and enzyme-inhibitor complex having a low level of activity resistant to autodegradation.

Cellular activation of the 72 kDa type IV procollagenase/TIMP-2 complex

Members of the collagenase family of enzymes have been implicated as central mediators of a number of both physiologic and pathologic processes. The 72-kDa type IV collagenase is secreted as a latent proenzyme, complexed with tissue inhibitor of metalloproteinase-2 (TIMP-2). Like other members of the collagenase family, this enzyme complex must be converted to a catalytically active form for proteolytic remodeling of extracellular matrix to occur. In the current study we demonstrate an inducible cell-mediated activation of the 72-kDa type IV procollagenase/TIMP-2 complex. Isolation of the 62 kDa activated enzyme/TIMP-2 complex from conditioned media of concanavalin A treated WI-38 fibroblasts demonstrated that the cell activated species was proteolytically active and amino terminal sequencing gave the sequence YNFF. This is identical to that of the 62 kDa species generated following organomercurial activation of purified 72-kDa type IV procollagenase/TIMP-2 complex. We have also isolated biosynthetically 35S-labeled 72-kDa type IV procollagenase/TIMP-2 complex and used this to further study the cellular activation process. In cell lines tested the activator was retained in the residual cell fraction following lysis in the presence of 0.2% (wt/vol) Brij-35. Inhibitor studies demonstrated that processing and activation of 72-kDa type IV procollagenase/TIMP-2 complex by the residual fraction was inhibited by 5 mM ethylenediaminetetraacetic acid and 0.5 mM 1,10-phenanthroline demonstrating a metal atom dependence. The species responsible for activation could be partially recovered in soluble form with 0.5% (vol/vol) Triton X-100 and 0.25% (wt/vol) CHAPS but was not salt extractable.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutations of p53 gene in hepatocellular carcinoma: roles of hepatitis B virus and aflatoxin contamination in the diet

BACKGROUND

Mutations of the p53 tumor suppressor gene have been reported in 50% of patients with hepatocellular carcinoma (HCC) from China and South Africa. These reports suggested an association of p53 mutations with high levels of aflatoxin in the diet. Most studies of p53 and HCC, however, have not fully evaluated the possible role of the hepatitis B virus (HBV). Aflatoxin is a substance produced by food mold that is known to cause HCC in experimental animals.

PURPOSE

The purpose of this study was to evaluate the relationship of p53 gene mutation to high or low levels of aflatoxin in the diet and to HBV infection.

METHODS

p53 protein and hepatitis B surface antigen (HBsAg) were evaluated by immunohistochemistry using the avidin-biotin-peroxidase system in paraffin-embedded specimens of HCC and of adjacent nontumorous liver tissue from 43 patients. Tissue specimens from three normal human livers were also evaluated. HCCs and adjacent nontumorous liver tissues were obtained from 23 patients from Qidong, China, where aflatoxin levels in the diet are high, and from 20 patients from two regions in the United States (patients from the National Institutes of Health, Bethesda, Md., and Kuakini Medical Center, Honolulu, Hawaii), where aflatoxin levels in the diet are low.

RESULTS

Mutant p53 protein was detected in the nuclei of HCCs from 14 (61%) of 23 patients from China and from three (30%) of 10 patients and six (60%) of 10 patients, respectively, from the two regions of the United States. A statistically significant association between detection of mutant p53 protein in HCC cells and the detection of HBsAg in hepatocytes of the adjacent nontumorous liver tissue was observed in patients from China and the United States considered together.

CONCLUSION

Mutations of the tumor suppressor gene p53 in hepatocellular carcinomas are not limited to patients from geographic regions where the ingestion of aflatoxin is high. In many patients, these mutations may be associated with HBV infection.

IMPLICATIONS

The possible interaction of chronic HBV infection and p53 gene mutation, suggested by these data, indicates a mechanism by which HBV infection beginning early in life could contribute to the subsequent development of HCC.

Higher-order complex formation between the 72-kilodalton type IV collagenase and tissue inhibitor of metalloproteinases-2

The collagenases are a class of matrix degradative enzymes whose actions are important in physiological and pathological processes. The human 72-kDa type IV collagenase (matrix metalloproteinase-2) and its proteinase inhibitor, tissue inhibitor of metalloproteinases-2 (TIMP-2), are produced as a proenzyme-inhibitor complex by numerous cell lines. We analyzed the quaternary structure of and enzyme-inhibitor interactions in the native enzyme-inhibitor complex by studying the pattern of complexes demonstrated by molecular weight determination in nondenaturing polyacrylamide gels and evaluating the products formed by reaction of the native complexes with cross-linking agents. Electrophoresis in native polyacrylamide gels demonstrates that approximately 79% of the latent enzyme is present in a 1:1 bimolecular complex with the inhibitor TIMP-2, with 21% present as a complete tetrameric complex of two molecules of collagenase combined with two molecules of TIMP-2. The enzyme complex activated with organomercurials displays a shift to a higher proportion of the bimolecular complex with only 5% present as higher molecular weight complexes. Cross-linking of the latent and active forms of the complex with bis(sulfosuccinimidyl) suberate (BS3) and bis(sulfosuccinimidyl) tartarate demonstrates both the 1:1 and 2:2 complexes as well as an intermediate form that appears to be a complex composed of two molecules of collagenase and one of TIMP-2. The distribution of cross-linked products is unchanged with the addition of excess TIMP-2 to the reaction mix, implying that the binding sites for TIMP-2 to the initial enzyme-inhibitor complex are all occupied when the stoichiometry is 1 to 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Unusual aspects of allergic bronchopulmonary fungal disease: report of two cases due to Curvularia organisms associated with allergic fungal sinusitis

We report two cases of allergic bronchopulmonary fungal disease (ABPFD) caused by Curvularia sp and associated with allergic fungal sinusitis (AFS). Curvularia lunata was cultured in one case and Curvularia senegalensis was cultured in the other. Based on these cases and a review of the literature, we discuss unusual clinical and pathologic features that can occur in ABPFD. Unusual clinical aspects of ABPFD include associated AFS, absence of asthma, progression to Churg-Strauss angiitis and granulomatosis, concomitant hypersensitivity pneumonitis, and underlying cystic fibrosis. Atypical pathologic features that may occur in ABPFD include follicular bronchiolitis, xanthomatous bronchiolitis, limited tissue invasion, fungus balls, and association with unusual fungi. Prominent follicular bronchiolitis and xanthomatous bronchiolitis were misleading histologic features in one of our cases and led to a delay in recognition of the diagnosis. Both patients presented primarily with AFS; ABPFD was detected subsequently. This suggests that a small subset of patients with AFS may be at risk for ABPFD. The goal of this review is to increase awareness of unusual clinical and pathologic manifestations of ABPFD. It is hoped that this will result in accurate diagnosis and proper therapy, especially for patients who present with atypical features. Unusual fungal species should be considered in patients who have clinical findings compatible with ABPFD but who do not demonstrate immunologic reactivity to Aspergillus sp, especially Aspergillus fumigatus. In addition, ABPFD should be considered in patients with AFS who develop new pulmonary lesions.

Primary lymphoma of the liver in a patient with acquired immune deficiency syndrome and chronic hepatitis B

We describe the case of a homosexual man with asymptomatic infection with human immunodeficiency virus and hepatitis B virus who developed primary hepatic lymphoma. The lymphoma presented with rapid enlargement of the liver, and ultrasound examination revealed multiple hypoechoic lesions within the liver. Histological examination of the liver showed massive replacement by lymphomatous tissue, as well as changes of chronic active hepatitis B. Immunohistochemical stains for hepatitis B surface and core antigens were strongly positive in almost all hepatocytes, but not in tumor tissue. Whereas the occurrence of lymphoma probably is related to HIV infection, possible interactions between hepatitis B virus and HIV infection are discussed. Thus, the presence of mass lesions within the liver in a patient with HIV infection should raise the possibility of hepatic lymphoma even if there is no evidence of generalized lymphadenopathy.

Purification and properties of a secondary alcohol dehydrogenase from the parasitic protozoan Tritrichomonas foetus

A novel secondary alcohol dehydrogenase has been isolated from Tritrichomonas foetus, the protozoan parasite which is responsible for bovine trichomonal abortion. The enzyme has been obtained in apparently homogeneous form after a 120-fold purification from cell homogenates, thus indicating that this activity constitutes an unusually high 1% of the total cytosolic protein. The native Mr = 115,000, determined by polyacrylamide gel electrophoresis. Mobility on sodium dodecyl sulfate gels suggests that the enzyme is composed of 6-8 subunits, identical as to molecular size (Mr = 17,000). The enzyme catalyzes the reversible oxidation of 2-propanol to acetone, using NADP+ (and not NAD+) as the redox-active co-substrate. Other small secondary alcohols, such as 2-butanol, 2- and 3-pentanol, cyclobutanol, and cyclopentanol are substrates, as are the corresponding ketones of these alcohols. Primary alcohols, such as ethanol and 1-propanol, are oxidized at rates less than 5% of that observed for 2-propanol. Product inhibition studies demonstrate an ordered kinetic mechanism, wherein the co-substrate (NADP+/NADPH) binds to the enzyme prior to binding of the substrate (alcohol/ketone).

The effect of a phase transition on penetration of phospholipid monolayers by melittin and glucagon

The penetration of melittin and glucagon into phospholipid monolayers was studied by measuring compression isotherms of phospholipids in the absence and presence of various concentrations of protein in the subphase. Differences in molecular area were calculated as a function of protein concentration at constant pressure. Area change as a function of surface pressure at constant protein concentration was also calculated. Melittin showed greater affinity for penetration into phosphatidylglycerol (PG) than into phosphatidylcholine (PC) monolayers. The cutoff pressure for melittin penetration was 45 mN/m with PC and 60 mN/m (extrapolated) with PG. Dipalmitoyl PC and PG monolayers show phase transitions upon compression at 25 degrees C. Both melittin and glucagon showed increased penetration as measured by area change within the region of the phase transition with both lipids. Glucagon showed a cutoff pressure of 25 mN/m for penetration into dimyristoyl PC. The preference of glucagon for interaction with lipid bilayers in the gel phase is discussed with respect to monolayer penetration as a function of surface pressure.