Transcriptional initiation and postinitiation effects of murine leukemia virus long terminal repeat R-region sequences

Sequences within the R components of the long terminal repeats (LTRs) of several retroviruses are known to be involved at various steps in expression of the viral genomes. A series of experiments was performed to test whether sequences within the R regions of the murine leukemia viruses Akv and SL3-3 affect viral expression. By using plasmid clones of the viral LTRs linked to a reporter gene, deletion of the R region was found to decrease expression to variable extents in a series of mammalian cell lines, with the largest effects being detected in murine fibroblasts. R-region sequences from the human immunodeficiency virus type 1 LTR or a random sequence were unable to substitute for the murine leukemia virus sequences. Transcripts from the R-region-deleted templates were initiated at the proper site in the LTR, but their levels were decreased at least 10-fold. Nuclear run-on assays showed that the decrease caused by the R-region deletions was due, in part, to an effect on RNA polymerase loading, suggesting an effect on transcriptional initiation. The remainder of the activity was presumably due to a posttranscriptional effect. Analysis of the R-region sequences of murine leukemia viruses and related retroviruses led to the prediction of a conserved secondary structure in the transcribed RNA that might have a role in activity. We conclude that R-region sequences are of importance for the expression of a variety of retroviruses.

DNA binding properties of YB-1 and dbpA: binding to double-stranded, single-stranded, and abasic site containing DNAs

A number of eukaryotic DNA binding proteins have been isolated by screening phage expression libraries with DNA probes containing the binding site of the DNA-binding protein. This methodology was employed here to isolate clones of the factor that interacts with the W box element of the human major histocompatibility complex HLA-DQB gene. Surprisingly, several cDNA clones of YB-1, a cDNA clone that was previously isolated with a CCAAT element-containing sequence were found. Independently, the screening of phage expression libraries with depurinated DNA resulted in the isolation of YB-1 and dbpA, a previously isolated cDNA that has homology to YB-1. Additional characterization of YB-1 showed that it bound a wide variety of DNA sequences and suggested that the binding of this protein is promiscuous. Furthermore, we show that both YB-1 and dbpA bind to depurinated DNA better than undamaged DNA and that the extent of specificity of binding is influenced by Mg2+. Due to the lack of sequence specificity and high degree of binding to depurinated DNA, we suggest that these proteins might be involved in chromosome functions such as maintenance of chromatin structure or DNA repair that do not require sequence-specific binding.

[Heparin-associated thrombocytopenia, thrombosis and embolism. Side effects of thromboembolism prevention with low molecular weight heparin enoxaparin?]

Heparin-associated thrombocytopenia (HAT) is a rarely described adverse reaction of systemic administration of heparin that may be complicated by thrombosis, embolism and bleeding. Unfractionated heparin as well as low molecular weight heparin may provoke HAT. A case of HAT complicated by thrombosis and pulmonary embolism is described that came about during preventive postoperative anticoagulation with the low molecular weight heparin enoxaparin. Pathogenesis, diagnosis, prophylaxis and therapy of HAT are discussed.

Construction of a replication-competent murine retrovirus vector expressing the human immunodeficiency virus type 1 tat transactivator protein

A replication-competent Akv murine leukemia virus-based vector encoding the human immunodeficiency virus tat cDNA under control of the simian virus 40 early promoter sequences was constructed. The simian virus 40 tat sequences were placed within the U3 region of the 3' long terminal repeat. The resulting virus, derived by transfection, replicated efficiently in mouse NIH 3T3 cells and maintained the tat cDNA insert. It has been suggested that Tat function requires the presence of a human-specific cofactor, which is absent in murine cells. However, infection of murine cells with the Akv virus encoding tat resulted in significant transactivation of a human immunodeficiency virus long terminal repeat-driven reporter gene, indicating that human cofactors are not always required for Tat function. The vector system described may be useful for introduction of foreign genes in vivo and in whole animals when virus spread is required for efficient infection and levels of gene expression.

Analysis of the significance of two single-base-pair differences in the SL3-3 and Akv virus long terminal repeats

Two single-base-pair differences between the long terminal repeats (LTRs) of the T-lymphomagenic murine retrovirus SL3-3 and nonleukemogenic Akv virus were tested for effects on activity of the LTRs. Evidence was obtained from electrophoretic mobility shift assays for the presence of at least one factor in both T and non-T cells that bound to the region of the viral enhancers that contained the differences. However, no significant differences in activity in expression assays were detected when the two base-pair differences were exchanged between the two LTRs. Therefore, they do not contribute to the higher activity of the SL3-3 LTR in T-lymphoma cell lines.

[Poly-, multiple trauma and intra-abdominal injuries]

The present work deals with the problem of abdominal injuries in polytraumatized patients. The results were obtained from a retrospective study of the records of 530 polytraumatized patients treated at the Central Hospital of the German Federal Armed Forces (Bundeswehr). In all, 193 of these patients had abdominal injuries. The overall mortality was 23.8% (n = 126): mortality among the patients with abdominal injuries was 26% (n = 50). Abdominal injuries alone led to death in 9.1% (n = 1), but mortality increased to 18.4% when at least one extra-abdominal injuries was also present. A combination of abdominal injuries and two or more extra-abdominal lesion led to a mortality rate of 27%. Mortality was found to be age- and sex-related: in young children and patients over 55 years (especially those around 70) mortality was 33.3%-72%. Among the cases with fatal outcome there was a female-to-male ratio of 3:2. The most common causes of death were: hemorrhage shock (62.3%), head injuries (37.7%), septicemia (8.1%), pneumonia, and ARDS (5.4% each). Within the last eight years we have used the following supplementary examination methods: computed tomography, peritoneal lavage, and ultrasonography. The retrospective study has shown that CT is not the examination of choice. The reliability with lavage and ultrasonography was approximately the same, but lavage was found to be more dangerous. Therefore, we abandoned lavage and used sonography only. However, we are of the opinion that any surgeon should use the examination method that has yielded the best results for him or her, to ensure the best possible outcome for the patient.

[Correlation of lymph node size and metastatic involvement of lymph nodes in bronchial cancer]

For preoperative staging in lung cancer mediastinoscopy is in competition with X-ray, tomography, and computer-tomography (CT). Many authors certify a high sensitivity and specificity to CT in staging lung cancer preoperatively by measuring the diameter of the hilar and mediastinal lymph nodes. In this study we measured the diameter of 162 lymph nodes from 83 patients postoperatively. In view of staging we found no sufficient correlation between the diameter of the lymph nodes and their infiltration by cancer cells. Even 35.7% of the nodes with a diameter of more than 2 cm were not infiltrated. The data support the opinion that CT alone is not sufficient for preoperative staging in lung cancer.

Identification of a mammalian nuclear factor and human cDNA-encoded proteins that recognize DNA containing apurinic sites

Damage to DNA can have lethal or mutagenic consequences for cells unless it is detected and repaired by cellular proteins. Repair depends on the ability of cellular factors to distinguish the damaged sites. Electrophoretic binding assays were used to identify a factor from the nuclei of mammalian cells that bound to DNA containing apurinic sites. A binding assay based on the use of beta-galactosidase fusion proteins was subsequently used to isolate recombinant clones of human cDNAs that encoded apurinic DNA-binding proteins. Two distinct human cDNAs were identified that encoded proteins that bound apurinic DNA preferentially over undamaged, methylated, or UV-irradiated DNA. These approaches may offer a general method for the detection of proteins that recognize various types of DNA damage and for the cloning of genes encoding such proteins.

Relative importance of elements within the SL3-3 virus enhancer for T-cell specificity

Elements within the enhancer of T-lymphomagenic SL3-3 virus were examined for their contributions to transcriptional activity in T lymphocytes and non-T cells. A region containing two sequences homologous to the enhancer core consensus sequence and a sequence homologous to the binding site for factor LVb was found to have the largest effect on activity. Evidence was obtained that suggests that the activity of this region was greater in T lymphocytes than in non-T cells and that multiple elements within it were necessary for activity. A second region, containing sequences homologous to the binding site of factor NF-I and the glucocorticoid response element, had about a twofold effect on transcription in both T lymphocytes and non-T cell lines. The twofold effect was seen whether the region containing the cores and LVb site was present or not. These results indicate that the most important region for the specificity of SL3-3 enhancer activity and, presumably, for viral leukemogenicity comprises the core elements and the LVb site. DNA-protein-binding studies demonstrated that one cellular factor, S/A-CBF, bound to both core elements, while a second cellular factor, S-CBF, bound to only one of them. In combination with earlier studies, this indicates that cells contain multiple factors that bind to the critical region.

Types and correlates of blood/injury-related vasovagal syncope

This study investigated by interview, the initial syncopal episode of 103 blood/injury-related vasovagal fainters in order to examine two competing hypotheses concerning their origins. Graham (Circulation, 23, 901-906, 1961) postulated that the faint resulted when sympathetic nervous system (SNS) activity ceased on termination of a threat, leaving parasympathetic nervous system (PNS) activation unopposed. Engel [Fainting (2nd edn), 1962; Annals of Internal Medicine, 89, 901-906, 1978] proposed that when in the face of threat with SNS activation, escape is blocked, the PNS becomes activated as the conservation-withdrawal response, leading to syncope. We found cases clearly conforming to each of these formulations as well as some with characteristics of both, and some who fainted in response to blood or injury but with no perception of threat. The Graham and Engel types did not differ in terms of fear or avoidance of blood, injury, or medically-related situations nor did they differ in the frequency with which their parents reported blood/injury-related syncopal episodes. It is proposed that both may be activated by a common psychological mechanism involving cessation of a defensive posture. In contrast, the non-threat fainters showed significantly less medically-related avoidance and had a greater percentage (94%) of parents with positive faint histories.

Absence of mouse mammary tumor virus proviral amplification in chemically induced lymphomas of RF/J mice

RF/J mice are susceptible to the induction of thymic lymphomas by the carcinogens 3-methylcholanthrene and N-methyl-N-nitrosourea. Given the association of mouse mammary tumor virus (MMTV) with certain thymomas, we examined genomic DNA from chemically induced lymphomas of RF/J mice for new MMTV proviruses. Of 13 tissue culture lines derived from 3-methylcholanthrene-induced tumors, 5 had acquired new proviruses. MMTV amplification coincided with the appearance of viral mRNAs and proteins. However, no primary tumors or animal-passaged tumors contained new proviruses. These observations indicate that MMTV does not have a role in the tumor induction process, although it may become activated and amplified in tissue culture lines derived from tumors.

Differences in activities of murine retroviral long terminal repeats in cytotoxic T lymphocytes and T-lymphoma cells

Transcriptional activities of the long terminal repeats (LTRs) of various murine leukemia viruses were tested in the cytotoxic T-cell lines CTLL-1 and CTLL-2. In contrast to T-lymphoma cells, in which the LTRs of T-lymphomagenic virus SL3-3 and Moloney murine leukemia virus are more active than those of other viruses, transcriptional activity in these mature, interleukin-2-dependent cells is not correlated with the specificity of viral leukemogenicity. Several approaches were used to investigate the molecular basis for LTR activity differences in lymphoma cells and mature cytotoxic T cells. Deletion analysis of the Moloney virus LTR showed that the direct repeats associated with enhancer activity have, at most, a slight effect on expression in CTLL-1 cells, whereas they stimulate expression six- to eightfold in T-lymphoma cells. This suggests that the mature T-cell line lacks one or more factors present in T-lymphoma cells that function to augment transcription from the Moloney murine leukemia virus LTR. We also used recombinant viral LTRs to investigate the role of the enhancer core element of SL3-3 in CTLL-1 and CTLL-2 cells. A one-base-pair difference between the core sequences of SL3-3 and nonleukemogenic Akv virus, which is important for SL3-3 activity in T-lymphoma cells, had no effect in these cells. The inability to distinguish the single-base-pair difference in expression assays was correlated with the absence of binding of a cellular factor, S-CBF, to the SL3-3 enhancer core in extracts of CTLL-1 and CTLL-2 nuclei. These studies may have implications for identification of the target cells for viral leukemogenesis, as well as for tracing of changes in the transcriptional machinery during T-lymphocyte differentiation.

Identification of the SL3-3 virus enhancer core as a T-lymphoma cell-specific element

Transient expression assays were used to determine the sequences within the long terminal repeat (LTR) that define the high activity in T-lymphoma cells of the leukemogenic SL3-3 virus in comparison with that of the nonleukemogenic Akv virus. Each of these viruses contains sequences related to the consensus element, the enhancer core. The SL3-3 and Akv enhancer cores differ at a single base pair. Substitution of the Akv core element into the SL3-3 LTR decreased expression in T-lymphoma cells but not in other cell types. Likewise, substitution of the SL3-3 core sequence into the Akv LTR increased expression in T-lymphoma cells but not in other types of hematopoietic cells. These data indicate that the SL3-3 enhancer core sequence functions better than that of Akv in T-lymphoma cells, but in other hematopoietic cell types the two are approximately equivalent. Competition DNA-protein binding assays were used to assess what nuclear factors from T-lymphoma lines and non-T lines bound to the SL3-3 and Akv core elements. Factors were detected that bound specifically to either the SL3-3 or Akv core but not to the other. Another factor was detected that bound equally well to both. However, none of these factors was specific to T-lymphoma cells.

[Detection of glycosphingolipids of ABH and Le antigens on thin-layer plates using the PAP method]

Stroma from hemolyzed erythrocytes of blood groups 0, A1, B and A1B were obtained and subjected to butanol/phosphate buffer extraction. This extract was separated using HPTLC, and the ABH and Le substances were detected on the chromatogram using the PAP technique. The staining of the bands allowed specific demonstration of the serologically active glycosphingolipids present in the ABH and Le blood group substances. The antigens of the AB0 system showed a 3- to 12-band pattern. Each of the antigens Lea and Leb presented 3 bands. The slight differences in the levels of glycosphingolipids of equal chain lengths are probably due to differences in their chemical structures.

Blood/injury fear, fainting and avoidance of medically-related situations: a family correspondence study

The relationship of mutilation fear and fainting was examined in 204 students, (103 fainters and 101 non-fainters) by administering a series of questionnaires and a structured interview concerning the history, effects and circumstances of their fear and fainting. Two hundred and sixty of their parents completed the same scales along with a self-report version of the structured interview. Subjects were classified according to their fainting status and level of fear based on Mutilation Questionnaire scores, as phobic, fearful, and non-fearful fainters, and fearful non-fainters. Phobic and fearful fainters avoided significantly more medical and related situations due to their fear and fainting than fearful non-fainters and non-fearful fainters. Medical avoidance was best predicted by a linear combination of subjects' estimated probability of future fainting and number of past faint episodes. More females reported fainting and females reported greater fear, but they did not differ from males in fear-motivated avoidance of medical situations. A significant parent-child correspondence was found for fainting, but not for fear nor for avoidances. Implications of these findings for fear and fainting acquisition and its relation to avoidance were discussed.