Experimental infection of chimpanzees with hepatitis G virus and genetic analysis of the virus.

Hepatitis G virus (HGV) was transmitted to 2 chimpanzees by inoculation with human plasma containing approximately 10(8) genome equivalents (GE) of HGV. The infection was characterized by the late appearance (weeks 10 and 11 after inoculation [pi]) of viremia that persisted throughout the 120-week follow-up. Serum HGV titer increased steadily until it plateaued at 10(6)-10(7) GE/mL. However, despite this relatively high titer, neither of the chimpanzees developed hepatitis. The sequence of the viral genome, recovered from each chimpanzee at week 77 pi, differed from that of the inoculum by 5 nt (2 aa) and 27 nt (2 aa). Two more chimpanzees were inoculated with a first-passage plasma pool. The chimpanzee inoculated with approximately 10(6.7) GE of HGV had viremia at week 1 pi. However, the viral titer increased with the same kinetics as observed in the first passage. The second chimpanzee inoculated with approximately 10(4.7) GE of HGV had late appearance (week 7 pi) of viremia.

Hepatitis G virus infection before and after liver transplantation. Liver Transplantation Database.

The hepatitis G virus is a newly discovered flavivirus that has been linked to acute and chronic hepatitis of unknown cause. We determined the prevalence of hepatitis G virus infection in 179 selected patients undergoing liver transplantation at three centers participating in the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Liver Transplantation Database. Pretransplantation and posttransplantation specimens were tested for hepatitis G virus RNA by polymerase chain reaction. Before transplantation, 9 of 38 (24%) patients with fulminant hepatic failure, 9 of 62 (15%) with cryptogenic cirrhosis, 3 of 35 (9%) with cholestatic liver disease, and 5 of 44 (11%) with chronic hepatitis C were positive for hepatitis G virus RNA (P = .27). Patients with and without viral RNA were similar in clinical features, liver test abnormalities, and survival after transplantation. Posttransplantation serum specimens were tested from 73 patients; 9 of 11 (82%) who were positive for viral RNA before transplantation remained positive, but 35 of 62 (56%) patients who were initially negative became positive after transplantation, a rate consistent with that predicted from the number of blood products administered. Only 5% of de novo HGV infections could be attributed to preexisting hepatitis G virus RNA in the donor. Comparison of patients with and without hepatitis G virus infection showed no difference in incidence of hepatitis after transplantation. Thus, hepatitis G virus infection was present in 15% of patients before and appeared de novo in half of patients after liver transplantation. Although hepatitis G virus infection was not associated with poor outcome, the frequency of this infection after transplantation calls for further long-term evaluation.

Hepatitis G virus in patients with cryptogenic liver disease undergoing liver transplantation.

To examine the prevalence of hepatitis G virus (HGV) in end-stage liver disease of unknown cause and the role of HGV infection in posttransplantation hepatitis, we studied 46 patients undergoing liver transplantation (mean age, 50 years; M:F, 18:28) with cryptogenic cirrhosis. HGV RNA was detected by polymerase chain reaction (PCR) and was quantified by a branched DNA (bDNA) assay. The prevalence of HGV RNA was determined in samples collected before and after liver transplantation and was found to be 22% and 67%, respectively. We evaluated the prevalence of posttransplantation hepatitis in 25 patients, 16 of whom were HGV-positive and 9 were HGV-negative. The proportion of patients with hepatitis was not significantly different in the two groups (38% in HGV-positive and 22% in HGV-negative patients). The median histological scores were significantly higher in liver biopsies from patients with HGV infection than in those without HGV infection (2 [range, 0-14] and 1 [range, 0-3]; P = .01), but the histological scores were low overall. The duration of follow-up was similar in the two groups. HGV RNA levels were not correlated with the severity of liver disease based on histological score (r = -.08). Graft survival and patient survival were not significantly different. We concluded that liver disease was frequent (32%) after transplantation in patients with a pretransplantation diagnosis of cryptogenic cirrhosis, although the disease was generally mild. Although HGV RNA was demonstrable in the majority (67%) of patients after transplantation, there was no relationship between the presence of HGV RNA and the presence of posttransplantation liver disease. The finding of posttransplantation hepatitis in the absence of known viruses (A-G), suggests that other, as-yet-unidentified viruses may be important.

Prediction of breast cancer malignancy using an artificial neural network.

BACKGROUND: An artificial neural network (ANN) was developed to predict breast cancer from mammographic findings. This network was evaluated in a retrospective study. METHODS: For a set of patients who were scheduled for biopsy, radiologists interpreted the mammograms and provided data on eight mammographic findings as part of the standard mammographic workup. These findings were encoded as features for an ANN. Results of biopsies were taken as truth in the diagnosis of malignancy. The ANN was trained and evaluated using a jackknife sampling on a set of 260 patient records. Performance of the network was evaluated in terms of sensitivity and specificity over a range of decision thresholds and was expressed as a receiver operating characteristic curve. RESULTS: The ANN performed more accurately than the radiologists (P < 0.08) with a relative sensitivity of 1.0 and specificity of 0.59. CONCLUSIONS: An ANN can be trained to predict malignancy from mammographic findings with a high degree of accuracy.

Proteins secreted by human trabecular cells. Glucocorticoid and other effects.

The capacity of cultured human trabecular meshwork (HTM) cells to secrete an extracellular matrix was studied by indirect immunofluorescence. Synthesis of nine extracellular matrix (ECM) proteins known to be present in the normal trabecular meshwork was assessed in three HTM cell lines. Fourteen primary antibodies were used and cultures were labeled two and four weeks after confluence. The HTM cell lines showed consistent labelling patterns for the normal extracellular connective tissue constituents including collagens (types I, III, IV, V and VI), glycoproteins (laminin and fibronectin) and a basement membrane-associated proteoglycan. These antigens were localized to the basal cell surface in an extracellular reticular pattern corresponding to cell margins. Dextran addition at confluence helped to intensify the staining of these components, but ascorbate had no apparent effect. Interestingly, elastin, another normal component of the trabecular meshwork, was not identified under standard conditions, or after addition of ascorbate or dextran. However, elastin could be detected intracellularly following dexamethasone treatment for three days, and extracellularly in punctate deposits when this treatment was used for 1 or 2 weeks. Our findings indicate that HTM cells may be responsible for the secretion and maintenance of all the major ECM constituents of the trabecular meshwork. The elastin results suggest a possible mechanism contributing to obstruction of outflow in steroid glaucoma if increased amounts of elastin are also produced in vivo. This approach can also serve as a useful baseline for comparison with HTM cell lines treated with glaucoma medications or obtained from patients with glaucoma.

Localization of extracellular proteins of the human trabecular meshwork by indirect immunofluorescence.

We used monospecific antibodies on semithin frozen sections to identify and localize the major tissue constituents of the nonglaucomatous human trabecular meshwork. The trabecular beams (sheets and cords) consist of a basement membrane (subendothelial extracellular matrix) surrounding an interstitial central core of connective tissue (substantia propria). The basement membrane contains collagen types III, IV, and V, the glycoproteins laminin and fibronectin, and the basement membrane-associated heparan sulfate proteoglycan. The trabecular basement membrane is unlike most subendothelial basement membranes because it contains collagen type III and a relatively disorganized structure. The central core contains collagen types I and III, and elastin. The closely linked juxtacanalicular meshwork contains collagen type III, but no collagen type I or elastin. The connective tissue composition of the trabecular meshwork appears similar to other highly compliant and resilient tissues, such as lung, blood vessels, and conjunctiva.

Juxtacanalicular tissue in primary open angle glaucoma and in nonglaucomatous normals.

The juxtacanalicular (JXT) tissue was evaluated in 64 specimens from 36 nonglaucomatous normal persons and 28 specimens from 26 patients with primary open angle glaucoma (POAG). Morphometry was performed on more than 2000 electron micrographs taken from the entire JXT region of each of the 64 specimens studied. The concentration of three electron-dense materials (EDMs) believed to obstruct the JXT tissue in POAG was measured using precise and reproducible morphometric methods. There is a great deal of variability in the EDM concentration, but we could still measure a significant increase in EDM of about 0.2% each year in normal specimens. Specimens from patients with POAG who are younger than 40 years of age have an EDM concentration similar to that in normal specimens. After the approximate age of 40 years, a significant difference is observed in the EDM concentration between nonglaucomatous and POAG specimens. This difference represents an average increase of 23% in POAG. Such a difference is probably too small to account for the decrease in outflow facility characteristic of POAG.