A PMLRARalpha transgene initiates murine acute promyelocytic leukemia

The malignant cells of acute promyelocytic leukemia (APL) contain a reciprocal chromosomal translocation that fuses the promyelocytic leukemia gene (PML) with the retinoic acid receptor alpha gene (RAR alpha). To test the hypothesis that the chimera PMLRAR alpha plays a role in leukemogenesis, we expressed a PMLRAR alpha cDNA in myeloid cells of transgenic mice. PMLRAR alpha transgenic mice exhibited impaired neutrophil maturation early in life, which progressed at a low frequency over the course of several months to overt APL. Both the preleukemic state and the leukemia could be transplanted to nontransgenic mice, and the transplanted preleukemia could progress to APL. The APL recapitulated features of the human disease, including a response to retinoic acid. Retinoic acid caused the leukemic cells to differentiate in vitro and in vivo, eliciting remissions of both the preleukemic state and APL in mice. Our results demonstrate that PMLRAR alpha impairs neutrophil differentiation and initiates the development of APL. The transgenic mice described here provide an apparently accurate model for human APL that includes clear evidence of tumor progression. The model should be useful for exploring the molecular pathogenesis of APL and the mechanisms of the therapeutic response to retinoic acid, as well as for preclinical studies of therapeutic regimens.     

The isolability of the causative agent of pseudotuberculosis from rodents in Georgia

Since 1960 the cases of isolating the pseudopathogen agent have been recorded in Georgia at particular regular intervals. The accumulated material mainly involves epizootiological findings, which may provide a definite insight into the prevalence of this disease in Georgia. In 1960-1990, 31 strains were isolated in particular regions and populated areas; these included 17 strains from grey rats, 4 from house mice, 9 from common voles, and 1 from field mice. The particular constancy of isolation of the pseudotuberculosis pathogen from synanthropic rodents indicates that they may really infect humans, contrary to the opinion of G. P. Somov et al. who consider that among the synanthropic rodents there is only a chronic epizootic causing no animal death and that the role of the rodents in the spread of infection among humans is insignificant. However, doubt is cast on the validity of this proposition as the evidence for carriage alone among the rodents is lacking. The special literature contains no information on the dynamics of an epizootic process of pseudotuberculosis among the synanthropic rodents whereas the high pathogen detection rate in the viscera of these animals, recognized by Somov et al., mostly likely confirms the possibility of the course of epizootic manifested by the disease, but not only carriage. There is reason to consider pseudotuberculosis to be a naturally focal disease that is characterized by recurrent epizootics of varying intensity. Therefore, wild and synanthropic rodents may be as a reservoir and a source of infection. The circulation of the pathogen among wild and synanthropic rodents, in terms of their ability to be preserved and breed in the environmental objects, presents a permanent risk of not only sporadic cases, but also pseudotuberculosis outbreaks.     

Leptin levels do not change acutely with food administration in normal or obese subjects, but are negatively correlated with pituitary-adrenal activity

Modern liver surgery is based upon deep knowledge of the surgical anatomy of the liver and improvements with ultrasounds imaging techniques have provided multidimensional interpretations of the liver anatomy intraoperatively. The technical advances with real-time scanning combined with the pioneering efforts of the Japanese liver surgeons have permitted the dynamic adaptation of the functional liver anatomy to the real anatomy, thus intimately aiding in segment oriented anatomical resection. Intraoperative ultrasound afford several advantages such as viewing the internal anatomy in direct relationship to the surface landmarks under the probe, enabling higher frequencies resulting in greater image resolution. The utilization of intraoperative ultrasound can modify the tactics involved with resection of both primary and metastatic liver tumours. The routine use of intraoperative ultrasound is strongly advocated since more complex procedures can be performed safely since the surgeon proceeds with complete knowledge of the real liver anatomy when deciding the feasibility and extent of liver resection.     

Pancreatic cancer and comparison of a hospital-based tumor registry with a National Cancer Data Base

BACKGROUND: The Commission on Cancer of the American College of Surgeons has called upon institutions providing cancer care to compare practice patterns and outcomes with the National Cancer Data Base (NCDB). Using data from the Virginia Mason Tumor Registry (VMTR), we sought to compare our pancreatic cancer care patterns with those reported nationally, while critically evaluating the accuracy and usefulness of our registry. METHODS: A review of the 906 computerized patient files in the VMTR from 1973 to 1995 was performed, with more detailed data on patients from the last 5 years retrieved from 224 manual abstracts. These data were compared with the 1991 NCDB for pancreatic cancer. RESULTS: The percent of cases according to AJCC stage in the NCDB (n = 9,715) versus the VMTR (n = 149), respectively, with cases of unknown stage excluded, were stage I 22% versus 22%, stage II 9% versus 12%, stage III 17% versus 28% (P <0.05) stage IV 52% versus 38% (P <0.05). One-third of the cases in the VMTR 1991 to 1995 were of unknown stage; number of cases with unknown stage for NCDB was 26.6%. The percent of surgical procedures for the NCDB (n = 7,802) versus the VMTR (n = 224), respectively, was pancreatectomy 14% versus 11%, local excision 1% versus 0%, no cancer-directed surgery 83% versus 89% (P <0.05), unknown 2% versus 0% (P <0.05). The actuarial relative survival rates for the 1991 NCDB versus 1987 to 1995 VMTR was 3-year 18% versus 38%, and 5-year 14% versus 35%. CONCLUSIONS: In comparison with the NCDB, VMTR may have fewer stage IV pancreatic cancers, but improvement is needed in decreasing the number of patients for whom the stage is unknown, as many of these likely represent late stage disease. We have a similar resection rate and a higher survival compared with the NCDB, but a mechanism is not in place to statistically compare our survival data with those of the NCDB. Even though all accredited hospitals are required to have a tumor registry, our data were difficult to compare with those of the NCDB because of coding and reporting deficiencies and inability to statistically compare survival data. Before our practice patterns and outcomes can be compared with national standards, both the VMTR and the NCDB must have standardized data collection and better access to the data.     

Differential expression of two functional serine/threonine protein kinases from soybean that have an unusual acidic domain at the carboxy terminus

Two soybean cDNA clones, SPK-3 and SPK-4, encoding putative protein kinases were isolated and characterized. Both cDNAs encoded approximately 40-kDa serine/threonine kinases with unusual stretches of acidic amino acids in their carboxy-terminal regions, which are highly homologous to PKABA1 from wheat and ASKs from Arabidopsis. These kinases are encoded by one- or two-copy genes in the soybean genome. Notably, SPK-3 and -4 showed different patterns of expression in various soybean tissues. SPK-3 is highly expressed in dividing and elongating tissues of young seedlings but relatively weakly in tissues of mature plants. In contrast, SPK-4 showed relatively high and constitutive expression in all the tissues examined except for leaf tissues of mature plants. Although various stressors, such as dehydration and high salinity, increased the expression of both genes, the induction kinetics were different. The two genes also differed in their response to abscisic acid (ABA). SPK-3 was induced but SPK-4 was not affected by exogenously supplied abscisic acid. In accordance with these expression data analysis of the activity of a chimeric SPK-3 promoter::beta-glucuronidase (GUS) reporter gene by transient expression in tobacco leaves confirmed the inducibility of SPK-3 by salt and ABA. Polyclonal antibodies raised against a recombinant SPK-4 protein produced in Escherichia coli specifically recognized both recombinant SPK-3 and -4 proteins. Kinase assays using affinity-purified SPK-4/ antibody complexes with crude soybean extracts as substrate identified specific phosphorylation of two 41 and 170 kDa soybean proteins that were phosphorylated on serine residues. Taken together, our results suggest that SPK-3, and/or SPK-4 are functional serine protein kinase(s). Furthermore, SPK-3 and -4 may play different roles in the transduction of various environmental stresses.     

MMP and TIMP expression pattern in pleural effusions of different origins

The matrix metalloproteinases (MMP) are proteolytic enzymes that are essentially involved in the turnover of the extracellular matrix (ECM). Their activity is counterbalanced by specific antagonists, the tissue inhibitors of metalloproteinases (TIMP). In this study, we sought to analyze the expression of MMP and TIMP isoforms in pleural effusions from 88 patients. We compared MMP and TIMP isoform expression in transudates (n = 21) and exudates (n = 67), the latter divided into exudates of paraneoplastic (n = 46) or parainfectious (n = 21) origin. Zymographic and Western blot analyses revealed constant expression of interstitial collagenase (MMP-1), gelatinase-A (MMP-2), and TIMP-1 in all 88 samples. In contrast, analyses of gelatinase-B (MMP-9) demonstrated a specific expression pattern, with high expression in exudates and lack of expression in transudates. Neutrophil collagenase (MMP-8) was detected in trace amounts, and correlated with the number of neutrophils in the effusion. Low levels of TIMP-2 were detected only in exudates and not in transudates. Quantitative analysis of the expression ratio of gelatinase-B to gelatinase-A revealed statistically significant differences between effusions of different origin. The ratio was highest in exudates of paraneoplastic origin and lowest in transudates. Our data thus suggest that interstitial collagenase, gelatinase-A, and TIMP-1 play a role in homeostasis of the pleural space in vivo as constitutively expressed proteins, whereas gelatinase-B and TIMP-2 expression are induced in specific disease states. These observations contribute to the understanding of the pathophysiology of pleural effusions, and may help to characterize and possibly distinguish effusions of different origin.     

Persistence of hepatitis C virus in newborn mice brain cell culture

A model of chronic infection of primary cultures of suckling mouse brain (SMB) cells actively producing hepatitis C virus (HCV) is developed. Destruction and repopulation of cells was observed for at least 6 months; this phenomenon was paralleled by virus release in culture medium. Persistent HCV contained in SMB cultures induced a cytopathogenic effect in PS, BHK-21, Vero, HAK, and click embryo cell cultures, its infective titers being 10.0-12.0 lg TCD50/0.2 ml. Persistent HCV formed heterogeneous plaques under agar in chick embryo cells. The polymerase chain reaction (PCR) regularly detected the HCV RNA at the stage of cell destruction in the culture fluid of HCV-infected cell cultures. The cytopathogenic activity of persistent HCV was neutralized by anti-HCV positive patients' sera with the neutralization index of 8.0-9.0 lg. The results of persistent HCV neutralization were confirmed by PCR. Immunofluorescence detected virus-specific HCV antigens in 15-40% of infected cells. Hence, the SMB-HCV system realized the cytopathogenic potential of HCV circulating in the blood of patients with hepatitis C. This system is promising for the study of the pathogenesis of HCV infection at a cellular level, for screening for specific and nonspecific antiviral agents, and for preparing native virus-specific proteins and RNA.