Induction of c-fos and c-myc expression in T lymphocytes after treatment with recombinant interleukin 1-alpha

Our data demonstrate that an early-acting differentiation/growth factor, such as IL 1, can induce the sequential expression of c-fos and c-myc in lymphocytes. Because such a wide variety of agents induces c-onc expression in lymphocytes, we conclude that the expression of these cellular proto-oncogenes represents a common pathway of response of lymphocytes to an exogenous stimulatory signal regardless of the nature of the factor and its receptor.

Induction of c-fos and c-myc expression in T lymphocytes after treatment with recombinant interleukin 1-alpha

Our data demonstrate that an early-acting differentiation/growth factor, such as IL 1, can induce the sequential expression of c-fos and c-myc in lymphocytes. Because such a wide variety of agents induces c-onc expression in lymphocytes, we conclude that the expression of these cellular proto-oncogenes represents a common pathway of response of lymphocytes to an exogenous stimulatory signal regardless of the nature of the factor and its receptor.

Hemorrhage-induced alterations of rabbit basilar artery reactivity and sensitivity to serotonin

Subarachnoid hemorrhage has a profound effect on cerebrovascular reactivity. The present study noted a progressive change in the sensitivity and reactivity of rabbit basilar artery to serotonin after experimentally induced hemorrhage. The basilar artery exhibited an initial diminished response to serotonin for periods up to 6 hours after hemorrhage, whereafter the vessel gradually became hyperresponsive. The hypersensitivity became maximal 36 hours after hemorrhage and then began to return to normal. Such early onset of serotonin hypersensitivity and reactivity after subarachnoid hemorrhage has not been previously reported. The level of tension developed, however, suggests that serotonin alone is unlikely to cause vasospasm. The strict differentiation of spasm into early and delayed components is questioned.

Reactivity of rabbit basilar artery to alterations in extracellular potassium and calcium after subarachnoid hemorrhage

Hemolysis of periarterial clots after subarachnoid hemorrhage may liberate large quantities of K+ into the vicinity of cerebral blood vessels and possibly change their sensitivity to endogenous vasoactive agents. The current study examined the influence of subarachnoid hemorrhage on the sensitivity of rabbit basilar arterial segments to K+ and Ca++. An analysis of K+ and Ca++ dose-response curves demonstrated that incubated arterial segments isolated from animals with subarachnoid hemorrhage were substantially more sensitive to these cations than were corresponding controls. We speculate that chronically elevated K+ levels in areas of periarterial clot lysis or brain ischemia might initiate vascular smooth muscle depolarization and vasospasm. Our data provide additional rationale for the use of calcium channel blockers in preventing or treating vasospasm in cases of subarachnoid hemorrhage.

Detection of the intracellular ras p21 oncogene product by flow cytometry

Rapid identification of the expression of oncogene products in specific cell types could potentially be useful in the diagnosis and treatment of human malignancy. We have now observed that through the use of lysolecithin permeabilization and fluorescence-activated flow cytometry, cells expressing high levels of the v-Ha-ras oncogene product, p21, can readily be distinguished from the nontransformed parent cells in a rapid and quantitative manner.

Expression of transfected human interferon-gamma DNA: evidence for cell-specific regulation

The production of interferon-gamma (IFN-gamma) has been limited to two specific cell types of the immune system, T cells and large granular lymphocytes. Interleukin 2 (IL 2) appears to be the primary physiologic stimulus for IFN-gamma production in vitro, but other agents, such as antigens, phorbol myristic acetate, concanavalin A, or other plant lectins, may also act as effective inducing agents for IFN-gamma production. Little is known, however, as to the role, if any, that genetic factors may play in the induction process. We now report that, on stable transfection of the genomic human IFN-gamma 8.6 Kb BamH DNA fragment into a mouse T lymphoblast cell line, both mRNA expression and synthesis of human IFN-gamma were stimulated by both the physiologic ligand IL 2 and phorbol ester. In contrast, we have been unable to induce with extracellular stimulants IFN-gamma production or cytoplasmic mRNA after introduction of this gene into NIH 3T3 fibroblasts, thus suggesting that the extracellular regulation of the expression of IFN-gamma may be controlled by a developmental mechanism(s) intrinsic for cells of lymphoid lineage.

Expression of transfected human interferon-gamma DNA: evidence for cell-specific regulation

The production of interferon-gamma (IFN-gamma) has been limited to two specific cell types of the immune system, T cells and large granular lymphocytes. Interleukin 2 (IL 2) appears to be the primary physiologic stimulus for IFN-gamma production in vitro, but other agents, such as antigens, phorbol myristic acetate, concanavalin A, or other plant lectins, may also act as effective inducing agents for IFN-gamma production. Little is known, however, as to the role, if any, that genetic factors may play in the induction process. We now report that, on stable transfection of the genomic human IFN-gamma 8.6 Kb BamH DNA fragment into a mouse T lymphoblast cell line, both mRNA expression and synthesis of human IFN-gamma were stimulated by both the physiologic ligand IL 2 and phorbol ester. In contrast, we have been unable to induce with extracellular stimulants IFN-gamma production or cytoplasmic mRNA after introduction of this gene into NIH 3T3 fibroblasts, thus suggesting that the extracellular regulation of the expression of IFN-gamma may be controlled by a developmental mechanism(s) intrinsic for cells of lymphoid lineage.

Posttranscriptional control of human gamma interferon gene expression in transfected mouse fibroblasts

Human gamma interferon genomic DNA was introduced into NIH 3T3 fibroblasts by calcium phosphate precipitation and was not expressed in these cells at the cytoplasmic mRNA or protein level. Treatment of the transfected cells with cycloheximide (1 microgram/ml) induced the accumulation of cytoplasmic gamma interferon mRNA and biologically active human gamma interferon. Analysis of the nuclear enriched RNA from untreated cells indicated that human gamma interferon mRNA was present, suggesting that cycloheximide may act by inhibiting a specific nuclease or may enhance the processing or transport of the RNA from the nucleus to the cytoplasm.

Intracellular localization of human monocyte associated interleukin 1 (IL 1) activity and release of biologically active IL 1 from monocytes by trypsin and plasmin

The production of interleukin (IL 1) by normal human peripheral blood monocytes purified by Ficoll-Hypaque density sedimentation, Percoll-gradient sedimentation, and plastic adherence can be detected as early as 30 min intracellularly, and extracellularly within 1 hr after stimulation with lipopolysaccharide (LPS). Production of mRNA coding for the isoelectric point 7.0 species of IL 1 was also detected as early as 1 hr after LPS stimulation and reached a maximum level at 6 hr. Cell-associated IL 1 activity could be extracted with CHAPS detergent from every cell fraction (i.e., membranes, cytosol, and particulates), but was present mainly (greater than 95%) in the cytosol of LPS-activated monocytes and the myelomonocytic cell line, THP-1. The apparent m.w. of IL 1 activity on high pressure liquid chromatography gel filtration in every cell fraction was approximately 23,000 daltons, with a minor peak at 31,000 daltons, whereas the IL 1 activity in the culture supernatants was 17,000 daltons. Western blotting analysis of LPS-stimulated monocyte extracts showed two forms of IL 1 corresponding to 31,000 daltons and 25,000 daltons. Exposure of viable cells to trypsin and plasmin released biologically active 23,000 dalton IL 1 only from IL 1-producing cells such as activated monocytes and IL 1-producing Ebstein-Barr virus B lymphocyte cell lines. Consequently, biologically active IL 1 is presumably exposed on the outer surface of cell membranes. Furthermore, IL 1 release by human monocytes in plasminogen-depleted fetal calf serum was considerably decreased. Conversely, supplementation of plasminogen-depleted serum with purified plasminogen restored the IL 1 production, suggesting that plasmin or plasmin-like factors may be involved in the regulation of the release of IL 1 from IL 1-producing cells. In conclusion, the results suggest that IL 1 is rapidly produced, is pooled in the cytosol, and in part is processed by enzymes, is transferred to the plasma membranes, and is then released from the cells. Tissue plasminogen activator and serum enzymes such as plasmin may therefore be involved in the release of IL 1 from IL 1-producing cells.

Intracellular localization of human monocyte associated interleukin 1 (IL 1) activity and release of biologically active IL 1 from monocytes by trypsin and plasmin

The production of interleukin (IL 1) by normal human peripheral blood monocytes purified by Ficoll-Hypaque density sedimentation, Percoll-gradient sedimentation, and plastic adherence can be detected as early as 30 min intracellularly, and extracellularly within 1 hr after stimulation with lipopolysaccharide (LPS). Production of mRNA coding for the isoelectric point 7.0 species of IL 1 was also detected as early as 1 hr after LPS stimulation and reached a maximum level at 6 hr. Cell-associated IL 1 activity could be extracted with CHAPS detergent from every cell fraction (i.e., membranes, cytosol, and particulates), but was present mainly (greater than 95%) in the cytosol of LPS-activated monocytes and the myelomonocytic cell line, THP-1. The apparent m.w. of IL 1 activity on high pressure liquid chromatography gel filtration in every cell fraction was approximately 23,000 daltons, with a minor peak at 31,000 daltons, whereas the IL 1 activity in the culture supernatants was 17,000 daltons. Western blotting analysis of LPS-stimulated monocyte extracts showed two forms of IL 1 corresponding to 31,000 daltons and 25,000 daltons. Exposure of viable cells to trypsin and plasmin released biologically active 23,000 dalton IL 1 only from IL 1-producing cells such as activated monocytes and IL 1-producing Ebstein-Barr virus B lymphocyte cell lines. Consequently, biologically active IL 1 is presumably exposed on the outer surface of cell membranes. Furthermore, IL 1 release by human monocytes in plasminogen-depleted fetal calf serum was considerably decreased. Conversely, supplementation of plasminogen-depleted serum with purified plasminogen restored the IL 1 production, suggesting that plasmin or plasmin-like factors may be involved in the regulation of the release of IL 1 from IL 1-producing cells. In conclusion, the results suggest that IL 1 is rapidly produced, is pooled in the cytosol, and in part is processed by enzymes, is transferred to the plasma membranes, and is then released from the cells. Tissue plasminogen activator and serum enzymes such as plasmin may therefore be involved in the release of IL 1 from IL 1-producing cells.

Analysis of T cell receptors in highly purified rat and human large granular lymphocytes (LGL): lack of functional 1.3 kb beta-chain mRNA

Recent reports have suggested that the T cell receptor for antigen is somehow involved in the cytotoxicity of natural killer (NK) cells. However, we now report that highly purified, freshly isolated large granular lymphocytes (LGL) from both the human and rat, as well as LGL cultured in the presence of recombinant IL 2, express only the 1.0 kb beta-chain mRNA. The lack of a 1.3 kb mRNA, indicative of a functional beta-chain rearrangement, strongly suggests that a functional T cell receptor beta-chain is absent in freshly isolated LGL, thus making it extremely unlikely that this molecule is involved in target cell recognition by NK cells. These results also suggest that LGL are derived from a lineage distinct from T cells or develop before a functional rearrangement of the T cell receptor beta-chain.

Analysis of T cell receptors in highly purified rat and human large granular lymphocytes (LGL): lack of functional 1.3 kb beta-chain mRNA

Recent reports have suggested that the T cell receptor for antigen is somehow involved in the cytotoxicity of natural killer (NK) cells. However, we now report that highly purified, freshly isolated large granular lymphocytes (LGL) from both the human and rat, as well as LGL cultured in the presence of recombinant IL 2, express only the 1.0 kb beta-chain mRNA. The lack of a 1.3 kb mRNA, indicative of a functional beta-chain rearrangement, strongly suggests that a functional T cell receptor beta-chain is absent in freshly isolated LGL, thus making it extremely unlikely that this molecule is involved in target cell recognition by NK cells. These results also suggest that LGL are derived from a lineage distinct from T cells or develop before a functional rearrangement of the T cell receptor beta-chain.

Lack of gene rearrangement and mRNA expression of the beta chain of the T cell receptor in spontaneous rat large granular lymphocyte leukemia lines

Using the murine cDNA clone for the beta chain of the T cell antigen receptor, we have examined four highly cytotoxic rat large granular lymphocyte (LGL) leukemia lines for the expression of unique rearrangements and mRNA transcription of the genes coding for the T cell antigen receptor. In contrast to normal rat T cells and nine rat T cell lines, the LGL leukemia lines exhibited no detectable gene rearrangements in the beta chain locus after digestion of LGL DNA by four restriction enzymes. Northern blots containing RNA from these LGL tumor lines demonstrated a low level of aberrant or nonrearranged beta chain transcription (less than 10 copies per cell) but virtually no translatable 1.3 kilobase message. These results demonstrate that LGL leukemia lines which mediate both natural killer (NK) and antibody-dependent cell-mediated cytotoxicity (ADCC) activities do not express the beta chain of the T cell receptor. The nature of the NK cell receptor for antigen remains elusive.

Opportunistic pasteurella multocida meningitis

Pasteurella multocida bacteraemia and meningitis followed elective surgery on the sinuses. The organism is thought to have been derived from close contact with dogs, and the infection responded to appropriate antimicrobial drugs, the patient making a complete recovery.

Intracranial meningioma unmasked by elective general anesthesia: report of three cases

Three cases of intracranial meningioma unmasked by elective general anesthesia are reported. In each case, the meningioma was either asymptomatic or so subtly symptomatic that no suspicion of intracranial tumor had been entertained preoperatively. Each patient presented with failure to wake up after routine general anesthesia for a nonneurosurgical procedure. The management of unexplained failure to wake up after uncomplicated general anesthesia is discussed. Early computed tomographic scanning and neurosurgical consultation are suggested in such situations.

Delayed traumatic intracerebral hematoma: report of 15 cases operatively treated

Fifteen cases of delayed traumatic intracerebral hematoma (DTICH) operatively treated are reported. Patients who are awake or only drowsy on admission (Coma Grades 1 and 2, Grady scale) often undergo dramatic sudden neurological deterioration 48 to 72 hours after admission. Emergency computed tomographic scanning and prompt craniotomy for hematoma evacuation yield excellent clinical results in the majority of cases. Patients presenting in deeper grades of coma (Grades 3 to 5, Grady scale) who develop DTICH do quite poorly, often because the diagnosis is difficult to make and consequently is delayed. The development of DTICH is in our experience highly unpredictable, and often no clear secondary cause (hypercapnia, hypoxia, bleeding diathesis) can be demonstrated.

Large intramedullary neurofibroma of the conus medullaris: case report

A case of a very large intramedullary neurofibroma of the conus medullaris extending over 3 1/2 segments is reported. The tumor was successfully treated by midline myelotomy and radical excision with no exacerbation of the preoperative neurological deficit. Intramedullary neurofibroma is extremely rare, accounting for less than 1% of spinal neurofibromas. Myelotomy and radical excision under the operating microscope are recommended in such cases.

Thoracic outlet syndrome

Thoracic outlet syndrome can usefully be regarded as a peripheral entrapment syndrome. Disease processes or anatomical anomalies at the thoracic outlet may in suitable circumstances give rise to compression of neurological or vascular structures traversing the outlet. Investigation involves careful radiological and electrical assessment. Myelography is usually necessary and angiography may be required. Ninety per cent of patients present with neurological complaints and these can normally be managed conservatively. In the 10 per cent of patients who have vascular involvement urgent investigation and early surgery may be necessary if ischaemic complications are to be avoided.

Osteogenic sarcoma of the skull complicating Paget's disease: case report

A case of osteogenic sarcoma of the skull in a patient with a long-standing Paget's disease is reported. Osteogenic sarcoma arising within the skull is rare in Paget's disease, although the recent literature emphasizes that it is more common than was realized previously. Intraparenchymal brain invasion, which is rare and present usually only as a preterminal event, was found in this patient who presented initially with minimal neurological findings. Rapid neurological deterioration in this patient was due to macroscopic hemorrhage into tumor. Although microscopic hemorrhage is characteristic of this tumor, gross hemorrhage into osteosarcoma of the skull as a cause of sudden neurological deterioration has not been reported previously. Radical resection is the treatment of choice, although the prognosis for this tumor remains dismal.

Molecular cloning, genomic analysis, and biological properties of rat leukemia virus and the onc sequences of Rasheed rat sarcoma virus

Rasheed rat sarcoma virus (RaSV) has been shown to code for a protein of 29,000 Mr not present in replication-competent rat type C helper virus (RaLV)-infected cells. This protein is a fused gene product consisting of a portion of the RaLV p15 gag protein and the transformation-specific 21,000 Mr (p21) ras protein, which is also found in Harvey murine sarcoma virus. We now report the molecular cloning of both the SD-1 (Sprague-Dawley) strain of RaLV and the transforming ras sequences of RaSV. Heteroduplex analysis of these cloned DNAs demonstrated that the RaSV ras gene (v-Ra-ras) was inserted into the rat type C viral genome with a small deletion of RaLV genetic information in the 5' region of the gag gene and that the v-Ra-ras gene (0.72 kilobase pair) is homologous to and colinear with the p21 ras gene of Harvey murine sarcoma virus (v-Ha-ras). Restriction enzyme mapping confirmed the homology demonstrated by heteroduplex mapping, showing strong site conservation of restriction endonucleases known to cleave v-Ha-ras. Cloned v-Ra-ras DNA transformed NIH 3T3 cells, inducing the synthesis of the p29 RaSVgag-ras protein.

Complications accompanying occipital skull fracture

One hundred thirty-four cases of occipital skull fracture seen over the past 15 years at the Medical Center Hospital of Vermont have been analyzed with respect to their clinical course and neurologic outcome. Among the cases reviewed, one third of patients had an uncomplicated course, 24% recovered with mild neurologic findings (such as cranial nerve palsy), and 13% died as a result of neurologic insult. This high morbidity results from combinations of traumatic subarachnoid hemorrhage, coup and contrecoup brain lesions, and injury at the skull base. Posterior fossa hematoma, cerebellar contusion, parietal and occipital lobe injury, and cranial nerve injuries associated with this lesion are discussed in detail. CAT scanning is now part of our diagnostic routine in patients with occipital fracture in coma grades 1-5 (Grady scale).

The p21 src genes of Harvey and Kirsten sarcoma viruses originate from divergent members of a family of normal vertebrate genes

The Harvey and Kirsten strains of murine sarcoma virus encode enzymatically and serologically related p21 src proteins which are required for virally mediated cellular transformation. The genes in each virus encoding p21 show such extensive divergence from each other that cloned probes from these genes detect distinct sets of cellular genes in the DNA from several vertebrate species. These data suggest that cellular p21 sarc genes constitute a divergent family of vertebrate genes that can regulate the growth of cells.

Analysis of two divergent rat genomic clones homologous to the transforming gene of Harvey murine sarcoma virus

Harvey murine sarcoma virus (Ha-MuSV) is a mouse-rat recombinant retrovirus that encodes a protein designated p21, required for virally induced transformation. Using a radiolabeled DNA fragment from the p21 coding region, we have detected homologous DNA sequences in the normal DNA of rats and of several other vertebrate species. Moreover, many tested cells from these species contain low levels of a p21 protein that is highly related to viral 21. Now we report two independent fragments from normal rat DNA containing sequences (sarc) homologous to the Ha-MuSV transforming region that were cloned in the bacteriophage vector Charon 4A. Sarc sequences in the one fragment are completely colinear with the viral sequences and share apparently all restriction endonuclease sites. Sarc sequences in the second fragment have several sets of intervening sequences and lack some restriction endonuclease sites found in the viral transforming region. Despite the presence of these intervening sequences in the second sarc fragment, we have been able to ligate this sarc fragment to the long terminal repeat sequence of HaMuSV and to induce cellular transformation and high levels of p21 expression upon transfection of this DNA to NIH 3T3 mouse cells. These results suggest that elevated levels of p21, normally expressed at low levels in a variety of cells, can induce cellular transformation.

Rat sarcoma virus: further analysis of individual viral isolates and the gene product

Rasheed rat sarcoma virus, derived by in vitro cocultivation of two rat cell lines (Rasheed et al., Proc. Natl. Acad. Sci. U.S.A. 75:2972-2976, 1978), has been reported to code for a protein of 29,000 Mr, immunologically related to the 21,000 Mr src gene product of Harvey and Kirsten sarcoma viruses. Rat sarcoma virus p29 was thought to contain at least part of a rat type C virus structural protein, since antiserum prepared against whole rat virus was able to immunoprecipitate rat sarcoma virus p29 but not Harvey or Kirsten sarcoma virus p21 (Young et al., Proc. Natl. Acad. Sci. U.S.A. 76:3523-3527, 1979). We now report that antiserum directed against rat type C virus p15, but not viral p12, p10, or p27, immunoprecipitated rat sarcoma virus p29. The p15 antiserum was also able to immunoprecipitate both denatured p29 and a peptide derived by V-8 protease cleavage of p29, indicating that this antiserum contains antibodies directed against primary amino acid determinants. Finally, five separate isolates of rat sarcoma virus were found to code for p29, which indicates that a highly specific site of recombination is involved in the generation of sarcoma viruses in rat cells.

Dual evolutionary origin for the rat genetic sequences of Harvey murine sarcoma virus

Detailed restriction endonuclease maps were developed for Harvey murine sarcoma virus (Ha-MuSV) DNA (clone H-1), molecularly closed at its unique EcoRI site in pBR322, for three nonoverlapping subgenomic HindIII clones which together span the entire H-1 clone and for a molecularly cloned DNA copy of a portion of rat 30S RNA (which represents the majority of the rat genetic sequences in Ha-MuSV). Molecular hybridization of the 30S clone to small restriction fragments of clone H-1 revealed a 0.9-to-1.0-kilobase pair region in the 5' half of the Ha-MuSV genome not homologous to the 30S clone, although the 30S clone did contain related sequences in Ha-MuSV on both sides of this nonhomologous region. By using cloned sequences from a segment of the Ha-MuSV nonhomology region as a probe for hybridization to Southern blots of DNA from rat, mouse, bat, and chicken cells, one to three bands were detected in DNA of each species. By contrast, the 30S clone DNA was highly related to many sequences in rat DNA, partially related to fewer mouse DNA sequences, and homologous only to one to three bands in bat and chicken DNA. Earlier work had shown that the 5' half of the Ha-MuSV genome coded for transformation and for the viral p21 protein (Chang et al., J. Virol. 35: 76--92, 1980; Wei et al., Proc. Natl. Acad. Sci. U.S.A., in press). We used two subgenomic HindIII clones whose shared HindIII site mapped within the 5' region of clone H-1 nonhomologous to the 30S clone to test whether the nonhomologous segment might encode the transforming and p21 functions. Although neither of the subgenomic HindIII fragments by themselves induced transformation, ligation of these two nontransforming DNAs to each other did restore p21-mediated transformation. A conclusion consistent with these results is that a region in the 5' half of the Ha-MuSV genome evolutionarily distinct from and not present in rat 30S RNA is essential for transformation and for p21 encoding.

Contrecoup intracerebellar hemorrhage: report of a case

A case of contrecoup intracerebellar hematoma is reported. Only one other similar case has been reported in the literature. This complication must be considered in head-injured patients, particularly in the presence of neurological deterioration in association with a cerebellar contusion demonstrated on the initial computed tomographic (CT) scan. Serial CT scanning is particularly important because of delayed intraparenchymal hemorrhage, which in this case occurred in the cerebellum.

Fractures of the sella turcica

Five recent cases of sella turcica fracture examined at the Medical Center Hospital of Vermont are reported. These fractures are most commonly associated with frontal or maxillofacial trauma and are complicated by cranial nerve palsies, chiasmatic injury, and cerebrospinal fluid rhinorrhea and otorrhea. The mortality rate with these fractures is high because of the associated brain injury. The importance of a detailed endocrine evaluation to detect developing pituitary abnormalities is also emphasized. The accuracy of radiographic diagnosis of these fractures utilizing plain skull films, tomography, and computed axial tomography is reviewed. the importance of cerebral angiography to evaluate the intracavernous internal carotid arteries and the basilar artery is also emphasized, as is the theoretical basis of the pathological findings associated with these fractures.

p21 of Kirsten murine sarcoma virus is thermolabile in a viral mutant temperature sensitive for the maintenance of transformation

We have recently described an intracellular protein, p21, in nonproducer cells transformed by either the Kirsten (Ki-MSV) or Harvey (Ha-MSV) strain of murine sarcoma virus (Shih et al., Virology, in press). The p21 is phosphorylated and has been shown to be coded for by either Ki-MSV or Ha-MSV. In this report, we compare the thermal stability of the newly synthesized [35S]methionine-labeled p21 in cells transformed by the wild-type Ki-MSV or by a mutant of Ki-MSV (ts 371) which is temperature sensitive in a viral function required for the maintenance of several properties of the transformed phenotype. The immunoprecipitability of the p21 coded for by the ts 371 Ki-MSV was markedly more thermolabile than the p21 of the wild-type Ki-MSV when the cell extracts are heated in vitro. The present finding suggests that the p21 is required for the maintenance of transformation induced by Ki-MSV.

Identification of a sarcoma virus-coded phosphoprotein in nonproducer cells transformed by Kirsten or Harvey murine sarcoma virus

A similar protein of 21,000 MW (p21) coded for by Harvey or Kirsten murine sarcoma virus has been identified in nonproducer cells transformed by these two viruses. Antisera prepared from rats bearing tumors induced by syngeneic transplantation of NRK cells transformed by Harvey murine sarcoma virus (Ha-MuSV) specifically precipitated the Ha-MuSV p21 from a nonproducer Balb/c mouse cell and a nonproducer dog cell transformed by Ha-MuSV. The same antisera also precipitated a similar protein, Ki-MuSV p21, from a nonproducer mink cell transformed by Kirsten murine sarcoma virus (Ki-MuSV). Both the p21 of Ha-MuSV and of Ki-MuSV are phosphoproteins. Previous studies have reported a virus-specific p21 polypeptide from translation of Ha-MuSV RNA in cell-free protein synthesis systems (W. P. Parks and E. M. Scolnick, 1977, J. Virol. 22, 711-719; T. Y. Shih, D. R. Williams, M. O. Weeks, J. M. Maryak, W. C. Vass, and E. M. Scolnick, 1978, J. Virol 27, 45-55). This p21 protein was specifically precipitated by the same anti-tumor sera. Similarly, a p21 polypeptide translated from Ki-MuSV RNA was also specifically precipitated by the antitumor sera. Therefore, it is concluded that the p21 of Ha-MuSV and Ki-MuSV are homologous proteins coded for bv homologous sequences found in the recombinant genomes of Ha-MuSV and Ki-MuSV.

Different rat-derived transforming retroviruses code for an immunologically related intracellular phosphoprotein

Kirsten sarcoma virus (Ki-MSV) and Harvey sarcoma virus (Ha-MSV) are mouse-rat recombinant viruses that were originally isolated by experimental inoculation of rats with helper-independent mouse type C viruses. We have recently identified in cells transformed by Ki-MSV or Ha-MSV, a phosphoprotein, p21, coded for by Ki-MSV and Ha-MSV [Shih, T.Y., Weeks, M.O., Young, H.A. & Scolnick, E.M. (1979) Virology 95, in press]. The p21, which is not a virion structural protein, was identified with antisera prepared by transplantation in rats of syngeneic Ha-MSV- or Ki-MSV-transformed nonproducer cells. In this study, we have applied the same methodology to examine a purely rat sarcoma virus (RaSV), which was isolated in cell culture by using helper-independent rat type C viruses [Rasheed, S., Gardner, M.B. & Huebner, R.J. (1978) Proc. Natl. Acad. Sci. USA 75, 2972-2976]. We report here that this new, purely rat sarcoma virus apparently codes for a p29, which shares immunological determinants and common V-8 protease-generated peptides with the p21 of Ha-MSV. The data suggest that the RaSV has acquired genetic information with similar coding capacity to some rat genetic information with similar coding combinant viruses, Ki-MSV and Ha-MSV. Based on data obtained on the p21 of a mutant of Ki-MSV temperature-sensitive for the maintenance of transformation, we suggest that the gene in RaSV that codes for the p29 is also required for the maintenance of RaSV-induced fibroblast transformation.

Expression of RNA of an endogenous replication-defective retrovirus in rat mammary adenocarcinomas induced by 7,12-dimethylbenz[a]anthracene

An investigation into the possible relationship between chemical carcinogen induction of rat mammary tumors and the expression of an endogenous retroviral genome was initiated. Mammary tumors were induced in female SD rats with 7,12-dimethylbenz[a]anthracene (DMBA). Tumors, identified histologically as mammary adenocarcinomas, were analyzed for RNA of a replication-defective endogenous retrovirus or RNA of a helper-independent endogenous type C virus. Expression of RNA of the replication-defective virus was detected in mammary tumors weighing 0.2--2.0 g. Larger tumors, for which histologic examination revealed proportionally more fibroblastic tissue than epithelial cells, did not contain comparable concentrations of this viral RNA. RNA homologous to a helper-independent rat type C retrovirus was not detected in tumors of any size. A cell line was established from a primary DMBA-induced mammary adenocarcinoma and appeared similar to the small mammary tumors with respect to endogenous type C viral RNA expression. We discuss possible implications of the expression of endogenous replication-defective viruses for use as markers for the effects of chemical carcinogens.

Eukaryotic gene regulation studies with mouse mammary tumor virus in tissue culture cells

The transcriptional regulation of mouse mammary tumor virus has been investigated in cell culture systems. These systems offer several insights into mechanisms of gene control including tenfold stimulation by glucocorticoids and spontaneous alterations in levels of constitutive transcription.

In vitro transcription of mouse mammary tumor virus RNA into DNA

The in vitro transcription of the B-type mouse mammary tumor virus RNA into DNA is similar to that obtained with certain C-type viruses: synthesis can be initiated on an RNA primer molecule approximately the size of a tRNA, and a unique linkage (rA-dC) exists between this primer and the DNA product.

Physical map of the Kirsten sarcoma virus genome as determined by fingerprinting RNase T1-resistant oligonucleotides

From analysis of the large RNase T1-resistant oligonucleotides of Kirsten sarcoma virus (Ki-SV), a physical map of the virus genome was deduced. Kirsten murine leukemia virus (Ki-MuLV) sequences were detected in T1 oligonucleotides closest to the 3' end of the viral RNA and extended approximately 1,000 nucleotides into the genome. The rat genetic sequences started at this point and extended all the way to the very 5' end of the RNA molecules, where a small stretch of Ki-MuLV sequence was detected. By comparison of the fingerprints of Ki-SV RNA and the RNA of the endogenous rat src genetic sequences, it was found that more than 50% of the T1 oligonucleotides were similar between Ki-SV and the endogenous rat src RNA, suggesting an identical primary nucleotide sequence in over 50% of the viral genomes. The results indicate that Ki-SV arose by recombination between the 5' and 3' ends of Ki-MuLV and a large portion of the homologous sequences of the endogenous rat src RNA.

In vitro transcription of Moloney leukemia virus genes in infected cell nuclei and chromatin: elongation of chromatin associated ribonucleic acid by Escherichia coli ribonucleic acid polymerase

The in vitro transcription of viral specific DNA sequences in nuclei and chromatin isolated from mouse cells chronically infected with Moloney murine leukemia virus (Mo-MuLV) has been studied. The in vitro RNA synthesized by Escherichia coli RNA polymerase has been isolated by sulfhydryl affinity column following reaction in the presence of 5-mercuriuridine triphosphate. By comparison of the Crt curves of the in vitro RNA with that of 70S viral RNA, the content of viral sequences is found to be 1.3% in nuclei product and 0.24% in chromatin product which is lower than the 2.5% found in chromatin associated RNA. This latter value, however, is very close to the in vivo viral RNA content in pulse-labeled [3H]RNA of the infected cells. Unexpectedly, it is observed that over 20% of the chromatin associated RNA prelabeled in vivo with [5-3H]uridine is elongated and tagged with Hg atoms during RNA synthesis catalyzed by the exogenous E. coli RNA polymerase in the presence of Hg-UTP. The elongation reaction is dependent on the presence of all four nucleotide triphosphates and appears to be due to E. coli RNA polymerase per se. It is suggested that most of the viral specific sequences observed in the in vitro RNA products are very likely initiated and derived from the chromatin associated species. The implication of the present findings for in vitro RNA synthesis in nuclei and chromatin as related to regulation of gene expression is discussed.

Laryngeal tetany: an unusual presentation of chronic renal failure

The presenting features and subsequent management of two adult patients with chronic renal failure complicated by laryngospasm are described. Possible mechanisms to explain this uncommon phenomenon are discussed but its rarity remains unexplained.

Detachment of the trachea following total laryngectomy

Two cases of tracheal detachment following laryngectomy are described and a suitable method of repair is suggested. The possible causes of detachment of the trachea following total laryngectomy may be summarized as follows: (a) Poor surgical technique when fashioning the tracheostome. (b) Poor quality of the tissues. (c) Poor general condition of the patient. (d) Excessive tension on the trachea. Reconstruction of the tracheostome requires:- (a) Elimination of infection by antibiotics and total debridement of non-viable tissue. (b) Absence of tension on the wound and the raising of adequate skin flaps. Should these conditions be met, the method of repair described above has been shown to be satisfactory.

Steroid induction of mouse mammary tumor virus: effect upon synthesis and degradation of viral RNA

Steroid hormones have been demonstrated to induce in tissue culture the production of mouse mammary tumor viral (MMTV) RNA, proteins, and particles 10-fold compared with constitutive levels. However, previous data of increased viral RNA levels did not distinguish between an increased rate of viral-specific RNA synthesis and a slower rate of viral RNA degradation. According to the recently developed assay of Coffin et al. (1974) for measuring rates of viral RNA synthesis, short-term labeling experiments of a mouse mammary tumor cell line indicate that the glucocorticoid hormone dexamethasone stimulates a 3-fold increase in the synthesis of MMTV-specific RNA within 10 min after the addition of hormone and that stimulation of RNA synthesis reaches 5- to 10-fold within 30 to 60 min, while the synthesis of Moloney leukemia virus-specific RNA in the same cell is unaffected by steroids. The decay rates of pulse-labeled and accumulated MMTV RNA in the presence or absence of dexamethasone show this RNA to have a half-life of greater than 8 h. In addition, hormone-stimulated MMTV RNA appears to have an increased rate of decay compared to basal MMTV RNA, thus ruling out an increased stability of MMTV RNA in the presence of steroid hormones as the basis for increased RNA levels. Thus, the magnitude, rapidity, and specificity of hormone action on MMTV RNA synthesis indicate a primary effect upon transcription.

Effect of chemical inactivating agents on glucocorticoid receptor proteins in mouse and hamster cells

The ffect of N-ethylmaleimide and iodoacetamide on the glucocorticoid receptor activity extracted from the cytosol of either mouse of hamster cells has been investigated. Treatment of mouse or hamster cytosol with N-ethylmaleimide or iodoacetamide rapidly inactivates the [3H]glucocorticoid hormone binding activity of either cytosol. Prebinding the glucocorticoid hormone, dexamethasone, to the cytosol receptor blocks the rapid inactivation of the receptor by N-ethylmaleimide. Treatment of the prebound hormone-receptor complex with iodoacetamide prevents the subsequent binding of the hormone-receptor complex to DNA without causing a dissociation of the complex. Although the conclusions may be limited by the lack of purity of the receptor, the results suggest that a sulfhydryl group is involved in the binding of glucocorticoid hormones to the receptor protein. In addition, the results suggest that iodoacetamide is inactivating a separate chemical site which is necessary for the binding of the hormone-receptor complex to DNA.

Mammary tumor virus induction by glucocorticoids. Characterization of specific transcriptional regulation

Dexamethasone (1,4-pregnadiene-9-fluor-16alpha-methyl-11beta,17alpha,21-triol-3,20-dione), a potent synthetic glucocorticoid, stimulates mouse mammary tumor virus expression 10- to 20-fold in tissue culture cells. This hormone effect was observed at concentrations as low as 1 times 10-10 M and was maximal at 10-7 to 10-8 M. The time course of induction indicated that detectable increases in extracellular viral DNA polymerase were first noted 18 to 24 hours following the addition of dexamethasone, and cells produced the highest polymerase levels at the time monolayers approached confluence. Steroid responsiveness was associated with specific increases in type B murine mammary tumor virus structural polypeptide (gp52(sl) expression and murine mammary tumor virus RNA that quantitatively paralleled the increase in extracellular virus production as measured by electron microscopy and supernatant RNA-dependent DNA polymerase activity. Another virally transformed murine cell line, KA 31, did not contain detectable levels of murine mammary tumor virus gp52(sl) or RNA before or after dexamethasone stimulation; thus induction was noted only in murine cells with pre-existing murine mammary tumor virus expression. No increase in basal levels of type C murine leukemia viral proteins or RNA was detected in dexamethasone-treated mammary cell lines which were producing increased levels of murine mammary tumor virus. Therefore, increases in murine mammary tumor virus gene products are specific for murine mammary tumor virus DNA sequences under these conditions.

Glucocorticoid-receptor interaction and induction of murine mammary tumor virus

The relationship between the cellular uptake of glucocorticoid hormones, the binding of these hormones to specific in vitro receptors, and the induction of mouse mammary tumor viruses in an established mouse mammary tumor cell line was highly correlated. These results suggest that the induction of mouse mammary tumor virus by glucocorticoid hormones is a physiological process acting through a mechanism of high affinity, saturable steroid-receptors. A temperature-sensitive or salt-dependent step following glucocorticoid-receptor interaction was required for nuclear uptake of the steroid. Induction studies with different adrenocorticoids indicate that the synthetic glucocorticoid, dexamethasone (1,4-pregnadiene-9-fluor-16alpha-methyl-11beta,17alpha,21-triol-3,20-dione), is the most potent inducer of mouse mammary tumor viruses and all steroids which caused significant induction were glucocorticoids. Other glucocorticoids appear to stimulate murine mammary tumor virus production by a mechanism similar to that of dexamethasone; for example, corticosterone competes with dexamethasone for binding to the glucocorticoid receptor and blocks the uptake of dexamethasone into cells. Progesterone also blocks the cellular uptake of dexamethasone and can bind to the glucocorticoid receptor at low concentrations (10-7 to 10-8 M) but progesterone does not consistently induce virus at hormone concentrations even as high as 10-4 M. Thus, in this system, binding to a cytoplasmic receptor is necessary but not sufficient for induction by glucocorticoids. Estrogens and androgens interfere with receptor binding and cellular uptake of dexamethasone but only at much higher concentration (10-4 M) than progesterone, and do not induce mammary tumor virus production. Although there was a positive correlation between steroid structure, binding, and biologic induction, other factors clearly affect the physiological manifestations of steroid actions. Mouse cells with comparable cytoplasmic receptor levels and comparable nuclear uptake differed absolutely in their degree of murine mammary tumor virus induction following hormone treatment. Although all mouse cells examined contain comparable levels of murine mammary tumor virus DNA, only cells producing constitutive levels of murine mammary tumor virus RNA could be induced to higher levels by a variety of glucocorticoids.