[Intermediate doses of cytosine arabinoside in the treatment of acute non-lymphoblastic leukaemia in children]

Between 1995-1997, at 7 centres of the Polish Paediatric Leukaemia/Lymphoma Study Group (PPLLSG) treatment was started in 102 children with acute non-lymphoblastic leukaemia. Sixty-two children treated according to the new protocol adjusted for risk factors were evaluated. Thirty-one patients belonged to standard risk and 23 to high risk group. Eight children were not evaluated due to early death. Out of 62 children, 44 (70,9%) achieved remission; in standard and high risk groups the rates of remission were 87,5% and 73%, respectively. Four-year event-free survival (EFS), relapse-free survival (RFS) and overall survival (OS) probability in all patients were: 40,2%, 42% and 59% respectively, in standard risk group: 49,5%, 52,5%, 59,1%; in high risk group: 42%, 43,4% and 57,8%. In comparison with the previous period (1983-1994) EFS increased from 30% to 42%, which was statistically insignificant.

Transmission of HCV infection among long-term hospitalized onco-haematological patients

Hepatitis C virus (HCV) infection is becoming a substantial problem in long-term hospitalized patients. Onco-haematological patients undergoing chemotherapy are especially prone to HCV infection. These patients are usually immunosuppressed and therefore antibodies to HCV are not produced despite the presence of HCV RNA in peripheral blood. The aim of the study was to see how often long-term hospitalized patients acquired HCV infection, and what were the possible sources and routes of virus transmission. The study involved 129 children with lymphoproliferative diseases, 36 patients with solid tumours, and 61 healthcare workers from onco-haematological wards. All were HCV RNA and anti-HCV negative at the time of first hospitalization. During a two and a half-year follow-up study among 165 onco-haematological patients, HCV RNA appeared in 87 in subsequent hospitalizations. The majority of infections were (82/87) were 1a genotype, 2 were 1b, 1 was 1a + 1b and 1 was 1a + 3a. In an attempt to establish the origin of HCV infection, healthcare workers were screened for HCV genotyping. All HCV-infected staff working on wards had the same genotype (1a). None of the staff was infected with 1b genotype. As the most prevalent genotype in Polish blood donors is 1b, HCV infection in onco-haematological patients is most likely due to horizontal transmission, probably involving genotype 1a, and potential horizontal transmission of HCV is implied by the presence of 1a genotype of HCV in saliva and urine of selected patients. Spread of hospital HCV infection among children may be facilitated by micro-injury of the skin and mucosa. Early detection of HCV RNA is important in such immunosuppressed patients, as they are not able to produce anti-HCV antibodies. This may enable the introduction of prophylactic steps to prevent the spread of HCV infection by horizontal transmission.

[Prevalence of TT virus in patients with hepatitis B,C and hepatitis of unknown etiology]

Discovery of TT virus in 1997 gave raise to intensive subsequent studies to learn about its structure, features and, what is the most important, about its role in pathogenesis of liver disease. The aim of the work was to analyze prevalence of TTV DNA in patients with diagnosed hepatitis B, C, that of unknown etiology and in healthy blood donors as well. Additionally the divergence of TTV sequence was estimated in selected cases. TTV DNA was detected by PCR technique using specific oligonucleotide primers for coding regions. TT virus has been detected in 25.6% (32/125) HBsAg positive patients and in 23.9% (51/213) HCV infected patients. In healthy blood donors the frequency of TTV was 24.3% (34/140) similarly to that found in HCV and HBV infected patients. The frequency of TTV DNA among patients with hepatitis of unknown etiology was 9.1%. This result was statistically significant lower than in the other groups. When detected sequences have been compared to these from NCBI base the homology result was 71% to 95%, and among different patients and groups of patients identity was 46% to 73%. On the basis of the obtained results it can be concluded that it is very unlikely that TTV coinfection plays any significant role in HCV or HBV infection. The hypothetical role of TTV infection in the etiopathogenesis of cryptogenic chronic hepatitis has not been confirmed. The results obtained in the small group of patients with hepatitis of unknown etiology are not conclusive and should be taken with some precaution. The final conclusion is the TTV coinfection does not contribute to the liver pathology. The divergence of TTV sequences may explain the various frequency of TTV viremia reported by other authors.

[Role of TT virus in pathogenesis of liver diseases--the prevalence of TTV in patients and healthy individuals]

Primarily TTV has been thought as an etiologic agent of post transfusion non-A to -G hepatitis. TTV can replicate in liver and bone marrow cells. The presence of TTV has been found in the serum of patients with acute as well as chronic hepatitis of known etiology. Patients with acute hepatitis A, B, C and hepatitis caused by EBV or CMV all have TTV viremia in a frequency up to 60%. In chronic viral hepatitis TTV was present in a wide range of 7-94.4%. Treatment of viral hepatitis patients with interferon alfa and rybawiryn leads to eradication of TTV viremia in 50% cases. TTV infection in hepatocellular carcinoma ranged from 8.1% up to 100% patients. In hepatitis of unknown etiology TTV infection was observed in 26% to 71% cases. In liver cirrhosis TTV infection has been evidenced in 10% to 66% patients. Some authors postulated that the frequency of TTV increased with the number of blood or blood products transfusions. Coinfection of TTV has been found in 34.9%-76% of HIV positive persons. The study of medical staff revealed no difference in TTV viremia with healthy individual control. TTV is widespread in healthy general population. Therefore based on so far published results the association between TTV infection and hepatitis is questionable.

[TT virus--characteristics, occurrence and routes of transmission]

Recent discovery of a novel DNA virus from the serum of a Japanese patient (T.T.) has prompted further studies directed on possible role of TT virus in the development of cryptogenic hepatitis. The TT is an unenveloped and circular DNA virus. TTV possesses single stranded DNA genome and comprises 3537 to 3853 nucleotides. TTV is similar to the Circoviridae and possesses three open reading frames. Phylogenetic analysis revealed up to 30% nucleotide sequence divergence in the 16 virus genotypes. TTV infection can be detected by polymerase chain reactions, in situ hybridization and by specific antibodies to TTV. TTV DNA has been identified in the serum of patients with cryptogenic hepatitis, hepatitis B and C, hepatocellular carcinoma as well as in healthy individuals. TTV has been found also in the peripheral blood leukocytes, bone marrow cells, liver biopsies as well as in feces and breast milk. Some animals including cattle, sheep, pigs and chicken appeared to have TTV viremia. Recent detection of TTV in nonblood products, such as saliva and feces suggest in addition to parenteral also nonparenteral routes of TTV transmissions including sexual and fecal-oral.

Significance of molecular identification of hepatitis C virus RNA in diagnosis of cryptogenic hepatitis in children

Viral etiology of hepatitis is routinely proved by standard immunological tests detecting specific antibodies. However, identification of specific antibodies cannot always be conclusive. Since specific hepatitis C virus (HCV) antibodies may appear after some months of the infection, identification of HCV RNA and/or hepatitis G virus (HGV) RNA should clarify the etiology of hepatitis. The aim of this study was to diagnose etiologically unknown hepatitis by a reverse transcription-polymerase chain reaction (RT-PCR) testing of the presence of HCV RNA and HGV RNA. The study involved 33 children with histologically proved hepatitis. The presence of HCV and any signs of autoimmune disease were not observed at the beginning of the follow-up study. During 2.5 years of the follow-up HCV-RNA was found in the blood and liver biopsies in 17 patients. Eight of them became HCV antibodies-positive during the follow-up. None of them eliminated the virus from the blood during the follow-up. In two other patients HCV-RNA was found only in the liver. HGV infection in all cryptogenic patients was excluded by PCR testing. Identification of HCV RNA RT-PCR allowed to diagnose 19 out of 33 (57.6%) patients with cryptogenic hepatitis. The etiology of the hepatitis in remaining 12 patients has to be established.

Hepatitis G virus co-infection may affect the elimination of hepatitis C virus RNA from the peripheral blood of hemodialysis patients

Hemodialysis patients are at risk for hepatitis C virus (HCV) and hepatitis G virus (HGV) infection. The aim of this study was to investigate the possible influence of HGV co-infection on HCV RNA elimination from the peripheral blood of hemodialysis patients. The study involved 144 persons, all with HCV antibodies and HCV RNA. Among 144 patients 24 (16.7%) were positive for HGV RNA. After 2.5 years of observation 80 patients (55.6%) were still HCV RNA-positive. In the latter group 18 patients were co-infected with HGV and 62 were HGV RNA-negative. During 2.5 years of the follow-up study 64 patients eliminated HCV RNA from the serum. In this group only 6 patients were HGV co-infected. None of the HGV-positive patients eliminated HGV RNA from the serum. The higher incidence of HGV co-infection in the group of patients who remained HCV RNA-positive (18/80, 22.5%), in comparison to the group of HCV antibodies-positive patients who lost HCV in the blood (6/64, 9.4%, P < 0.0001) suggests, that the co-infection with HGV may delay the spontaneous elimination of HCV RNA from the blood.

[Genetic determination of smell]

The recent study of olfactory receptor genes sheds new light on the significance of this receptor not only for smell recognition but also in human embryogenesis. In this work current data concerning the role of olfactory receptors in human as well as their genetic determination are presented. Olfactory receptors are encoding approximately by 1000 hOR genes. The hOR gene family is most likely the largest in human genome. Among 1000 hOR genes, 347 are functional, the rest 70% being pseudogenes are not expressed. HOR genes reside at 25 locations in human genome in multiple clusters on all human chromosomes, except 2, 4, 18, 20, 21, and Y. Each receptor recognizes single as well as multiple odorant, and each odorant binds to multiple receptors to generate specific activation patterns for each of a great number of distinct smells. There is more and more evidence showing close correlation between HLA complex and smell recognition, which influence mating behavior in animals, consequently leading to increase immune response to various pathogens. The last investigations showed hOR expression in germinal cells and in developing embryo, suggest that hOR may play functional role in cell recognition in organogenesis.