Isolation and RNA-binding analysis of NAD+-isocitrate dehydrogenases from Kluyveromyces lactis and Schizosaccharomyces pombe

Krebs cycle NAD⁺-isocitrate dehydrogenase (Idh) binds to the 5-UTRs of all mitochondrial mRNAs in Saccharomyces cerevisiae. We hypothesize that this leader-binding activity plays a role in translational regulation, thereby linking mitochondrial biogenesis to the need for respiratory function. Analysis of effects of leader binding on mitochondrial translation is complicated by the involvement of the enzyme in mitochondrial metabolism. We have therefore searched for an Idh altered in RNA binding, but retaining full enzyme activity. Idh from Kluyveromyces lactis and Schizosaccharomyces pombe was partially purified and examined for the ability to bind Cox2 mRNA. Sch. pombe Idh, like the S. cerevisiae enzyme, has high affinity for both its own, K. lactis and S. cerevisiaeCOX2 leaders. In contrast, Idh purified from K. lactis shows only low affinity for all mRNAs tested. To determine what distinguishes K. lactis Idh from S. cerevisiae Idh, genes encoding the two subunits of Idh in K. lactis were cloned and sequenced. Sequence comparison revealed high levels of similarity throughout the proteins, in particular in regions involved in enzyme activity, co-factor and regulator binding. Non-conserved residues between the subunits from the two yeasts are candidates for involvement in the interaction with RNA. Received: 19 January 2000 / 24 March 2000     

Clinical significance of antibodies to nonstructural and core proteins of hepatitis C virus in posttransfusion hepatitis patients during long-term follow-up

The prevalence of hepatitis C antibodies (anti- HCV) among multitransfused patients was studied and compared with predicted values obtained from a post-transfusion hepatitis study and from data on the prevalence of anti-HCV among blood donors. The prevalence of hepatitis B core antibodies (anti-HBc) was also studied to determine the routes of transmission of hepatitis C virus. The patients consisted of 65 dialysis patients (57 on haemodialysis and 8 on continuous ambulatory peritoneal dialysis) and 71 leukemia patients in long-term remission [49 with acute myeloid leukemia (AML) and 22 with acute lymphatic leukemia (ALL)]. The presence of anti-HCV was investigated using a second generation enzyme-linked immunosorbent assay. Reactive samples were confirmed by a second generation recombinant immunoblot assay. Anti-HBc was studied in the 65 dialysis patients and in 40 of the leukemia patients. Three (4.6%) of the 65 dialysis patients and 12 (24.5%) of the 49 AML patients were anti-HCV positive whereas all of the ALL patients were seronegative. The total number of blood units transfused to 134 patients (data on two dialysis patients were not available) was 18,148, out of which 17,575 units had been transfused prior to the initiation of anti- HCV screening of blood donors. On the basis of the anti-HCV prevalence among blood donors and the incidence of post-transfusion hepatitis, the predicted number of seropositive patients was 11 and 18, respectively. Five of the 65 dialysis patients were anti-HBc positive, compared with only one of the 40 leukemia patients. It is concluded that the anti-HCV prevalence among dialysis and leukemia patients is concordant with the risk of receiving contaminated blood products, whereas hepatitis B infection may have other routes of transmission in dialysis patients. © 1993 Wiley-Liss, Inc.     

The exclusion among the Ustilago viruses — A dsRNA restriction modification system?

Summary Specific exclusion relations are know among the three Ustilago maydis viruses that are associated with the cytoplasmically transmitted killer phemomenon. Of the three viruses P1, P4 and P6, only P1, and P4 cancoexist in one host cell. Mutual exclusion occurs between P1 and P6 and P4 unilaterally excludes P6. The exclusion relations were originally defined among the wild-type viruses. Those relations can be modified by two specific segments that are a part of the P4 dsRNA genome and were also found in some sensitive strains that contained part of the viral genome. Also, deletion of the dsRNA segment that is assumed to encode the toxin information permits the formation of hybrid genomes that otherwise cannot be formed. The data is interpreted in terms of a dsRNA restriction modification system in which the killer toxin or a toxin-linked function acts as the restriction factor and segments H3 and H4 or H4 alone contain the necessary information for the modification of certain sites on the M and L segments of the P1 and P4 viruses but not on the P6 segments.     

The asymmetries in morphology, desoxyribonucleic acid, protein and ribonucleic acid of the two hemispheres induced by monolateral removal of the olfactory bulb and retrobulbar structures in neonatal rats

Monolateral removal of the olfactory bulb and the olfactory penduncular structures in the neonatal rat resulted in a profound morphological and biochemical asymmetry between the two hemispheres. The experimental hemisphere, ipsilateral to the lesion, protruded into the space normally occupied by the olfactory bulb and showed enlarged ventricles. The brain loci were displaced rostrally in this hemisphere.The desoxyribonucleic acid, ribonucleic acid and protein contents of the experimental hemisphere at 25 and 60 days of age were all significantly lower than that found in the control hemisphere contralateral to the lesion.To resolve between the two possible causes of this asymmetry (i.e. atrophy of the experimental or hypertrophy of the control hemisphere) hemispheres of the asymmetric brain were compared with homonymous hemispheres of unoperated normal rats. This comparison revealed that the asymmetry is basically due to an excess of desoxyribonucleic acid synthesis in the control hemisphere, which continues even after postnatal day 25, on the one hand, and a dearth of protein in the experimental hemisphere on the other. This finding implies two separate mechanisms for the processes that underlie the asymmetries observed for these two substances.Our results demonstrate two important characteristics of the developing brain. Firstly they indicate that removal of the olfactory bulb and the olfactory peduncle can produce considerable changes in the hemispheres, and secondly they unravel the strong latent potential of the brain for cell proliferation beyond the usual period of cell division in the brain. As in these experiments regulation of cell division is affected, this system might serve as a model for the study of aberrant cell division found in tumor formation and the process of carcinogenesis.     

Integrated medical informatics with small group teaching in medical education

National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.     

Molecular identification of a novel human rotavirus in relation to subgroup and electropherotype of genomic RNA

A total of 41 stool rotavirus specimens collected from children with acute diarrhea at four different locations in Akita Prefecture, Japan, during the peak of the winter diarrhea epidemic in 1988 were analyzed by polyacrylamide gel electrophoresis of viral RNA in conjunction with subgrouping assay. We found that a single strain predominated, with cocirculating strains with less common electropherotypes at a given location, and that two different strains could predominate at geographically close but different locations even during a very limited time of the epidemic season. Furthermore, we isolated a human rotavirus strain (AU125) that was similar to the AU-1 strain in that it possessed a long RNA pattern yet belonged to subgroup I. Genetic analysis by RNA-RNA hybridization assay indicated that the AU125 strain was distinct from two previously identified human rotavirus gene groups (genogroups) represented by the Wa strain (subgroup II with long RNA electropherotype) and the DS-1 strain (subgroup I with short RNA electropherotype), but was very closely related to the AU-1 strain. These data suggest that the genetic diversity of human rotaviruses may be more extensive than was previously thought.     

Neurological Manifestations of COVID-19 Feature T Cell Exhaustion and Dedifferentiated Monocytes in Cerebrospinal Fluid

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Metastatic potential of human CX-1 colon adenocarcinoma cells is dependent on the expression of sialosyl Le a antigen

Several lines of evidence indicate that sialosyl Le a , tumor-associated carbohydrate antigen present on human colon carcinoma cells, is involved in formation of metastases. To study the role of this carbohydrate structure in development of metastases, we have used the clone of human colon carcinoma CX-1 cells transfected with antisense expression vector containing fragment of cDNA for a1,3/4-fucosyltransferase (FT III), which is involved in synthesis of sialosyl Le a tetrasaccharide. It has been reported previously that, in contrast to the parental cells, the antisense-transfected CX-1.1AS5 cells do not express sialosyl Le a and do not adhere to E-selectin-expressing CHO cells. In the present work we have studied the formation of liver metastases by CX-1.1AS5 cells after their orthotopic or intrasplenic implantation into athymic nu/nu mice. After orthotopic implantation of sialosyl Le a -negative colon carcinoma CX-1.1AS5 cells, the number of mice with liver metas-tases was markedly lower (21% of mice) in comparison with their number after implantation of the parental CX-1.1 cells (86% of mice). However, no differences in ability to form colonies in liver were observed between parental CX-1.1 cells and antisense-transfected CX-1.1AS5 cells after intrasplenic inoculation. The liver metastases were formed in 89% and 84% of mice, respectively. Our data support the thesis on the importance of sialosyl Le a antigen expression in the development of liver metastases by colon cancer cells, and indicate the role of transplantation route and primary tumor localization in formation of metastases.© Kluwer Academic Publishers 1998     

Differential RNA fingerprinting as a tool in the analysis of spermatozoal gene expression

The apparent decline in human male fertility and the concomitantincrease in testicular pathology have prompted discussion ofthe underlying molecular mechanisms which may underpin theseobservations. While monitoring the expression of protamlne-2genes in the human ejaculate, we found a representative complementof sperm mRNAs following sequence-independent amplificationof reverse-transcribed cDNAs with the polymerase chain reaction(RT-PCR). The revelation of unique sperm-derived PCR productsusing this method suggests that it should now be possible toinvestigate gene expression in human spermatogenesis by differentialRNA fingerprinting of ejaculate spermatozoa. The Identificationof molecular markers and the corresponding genes associatedwith male Infertility will be considerably enhanced by theseinvestigations while obviating the requirement for invasivebiopsy.