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Clean Cut (adaptive, multimodal surgical infection prevention programme) for low-resource settings: a prospective quality improvement study. Br J Surg 2021; 108:727-734. [PMID: 34157086 PMCID: PMC10364890 DOI: 10.1002/bjs.11997] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/17/2020] [Accepted: 07/23/2020] [Indexed: 11/06/2022]
Abstract
BACKGROUND Clean Cut is an adaptive, multimodal programme to identify improvement opportunities and safety changes in surgery by enhancing outcomes surveillance, closing gaps in surgical infection prevention standards, and strengthening underlying processes of care. Surgical-site infections (SSIs) are common in low-income countries, so this study assessed a simple intervention to improve perioperative infection prevention practices in one. METHODS Clean Cut was implemented in five hospitals in Ethiopia from August 2016 to October 2018. Compliance data were collected from the operating room focused on six key perioperative infection prevention standards. Process-mapping exercises were employed to understand barriers to compliance and identify locally driven improvement opportunities. Thirty-day outcomes were recorded on patients for whom intraoperative compliance information had been collected. RESULTS Compliance data were collected from 2213 operations (374 at baseline and 1839 following process improvements) in 2202 patients. Follow-up was completed in 2159 patients (98·0 per cent). At baseline, perioperative teams complied with a mean of only 2·9 of the six critical perioperative infection prevention standards; following process improvement changes, compliance rose to a mean of 4·5 (P < 0·001). The relative risk of surgical infections after Clean Cut implementation was 0·65 (95 per cent c.i. 0·43 to 0·99; P = 0·043). Improved compliance with standards reduced the risk of postoperative infection by 46 per cent (relative risk 0·54, 95 per cent c.i. 0·30 to 0·97, for adherence score 3-6 versus 0-2; P = 0·038). CONCLUSION The Clean Cut programme improved infection prevention standards to reduce SSI without infrastructure expenses or resource investments.
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Intensified tuberculosis case finding among HIV-infected persons using a WHO symptom screen and Xpert(®) MTB/RIF. Int J Tuberc Lung Dis 2016; 19:1197-203. [PMID: 26459533 DOI: 10.5588/ijtld.15.0230] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
SETTING Human immunodeficiency virus (HIV) clinic in Addis Ababa, Ethiopia. The World Health Organization (WHO) recommends active tuberculosis (TB) case-finding among people living with HIV (PLHIV) in high-burden settings. OBJECTIVE To evaluate the effectiveness of combining a WHO-recommended symptom screen and the Xpert(®) MTB/RIF test to enhance TB case finding. DESIGN In this cross-sectional study, PLHIV were screened for TB using a WHO-recommended symptom-based algorithm (cough, fever, night sweats, weight loss). Those with a positive symptom screen (⩾1 symptom) underwent diagnostic testing with smear microscopy, culture, and Xpert. RESULTS Of 828 PLHIV (89% on antiretroviral therapy), 321 (39%) had a positive symptom screen. In multivariate analysis, an unscheduled clinic visit (aOR 3.78, 95%CI 2.69-5.32), CD4 count <100 cells/μl (aOR 2.62, 95%CI 1.23-5.59) and previous history of TB (aOR 1.62, 95%CI 1.12-2.31) were predictors of a positive symptom screen. Among those with a positive symptom screen, 6% had active pulmonary TB. Smear microscopy sensitivity for TB was poor (30%) compared to culture and Xpert. CONCLUSIONS A positive symptom screen was common among PLHIV, creating a substantial laboratory burden. Smear microscopy had poor sensitivity for active TB disease. Given the high rate of positive symptom screen, substantial additional resources are needed to implement intensified TB case finding among PLHIV in high-burden areas.
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Ambulatory care for multidrug-resistant tuberculosis: lessons learned in Addis Ababa, Ethiopia. Public Health Action 2014; 4:S37-41. [PMID: 26478512 PMCID: PMC4542066 DOI: 10.5588/pha.14.0058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 09/15/2014] [Indexed: 11/10/2022] Open
Abstract
SETTING Ethiopia is one of the high multidrug-resistant tuberculosis (MDR-TB) burden countries. Efforts by the National TB Programme to control MDR-TB include expanding ambulatory care. OBJECTIVE To investigate the opportunities and challenges faced by treatment follow-up health centres (TFCs) when managing MDR-TB patients, with greater focus on recording, TB infection control (IC) and supervision practices. METHODS A facility-based cross-sectional study was conducted by reviewing the records of all MDR-TB cases in all 25 TFCs in Addis Ababa, Ethiopia. The TB focal point, pharmacy and laboratory heads were also interviewed. RESULT A total of 221 MDR-TB patients were registered; 157 (71%) patients had been referred from one of the two treatment initiating centres. While some TFCs oversaw up to 41 patients, others had just one patient. The majority of the TFCs (n = 21, 84%) followed standardised TB IC procedures. Poor documentation of patient information was observed at all sites; for example, human immunodeficiency virus and current treatment status was not indicated for respectively 86 (38%) and 41 (18%) patients. CONCLUSION The study revealed that infection prevention practices were largely adhered to. Documentation of patient-related information was a major challenge, and regular supervision of the TFCs should be emphasised. Record keeping is critical.
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The significance of bowel involvement in advanced epithelial ovarian cancer. Gynecol Oncol 2012. [DOI: 10.1016/j.ygyno.2011.12.222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Ocular injuries in a rural Ethiopian community. EAST AFRICAN MEDICAL JOURNAL 2008; 85:593-596. [PMID: 19413215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
OBJECTIVE To assess the causes, magnitude, risk factors and visual impact of ocular injury. DESIGN Community-based cross sectional study. SETTING Goro District Central Ethiopia between November 2002 and January 2003. SUBJECTS Sixty four peasant associations, with 1,566 people per peasant association. RESULTS Out of a total of 1027 people interviewed, 52 (5.1%, 95% CI: 3.8, 6.4) cases with history of ocular trauma, 24 (46.2%) males and 28 (53.8%) females, were examined. The mean age was 29.5 years. Of them, 18 (34.6%) were visually impaired in the affected eye. Ocular injury occurred most commonly among farmers 39/52 (75.0%). The difference between the number of males and females was not statistically significant (p = 0.5). But the relative risk (RR) of females (28/515 = 5.44) sustaining ocular injury compared to males (24/512 = 4.69) was 1.16 indicating that females had a 16% excess risk of having ocular injury than males. The leading cause of ocular injury in this community was by stick (35/52 = 67.3%). CONCLUSION Ocular injury is significant (5.1%) in the community and causes monocular visual impairment in about one third (34.6%) of cases. Females are relatively at higher risk of having an eye injury (RR = 1.16) and this is mostly work related injury with stick during local food processing. Activities directed to improving the technology of food processing will ultimately reduce the rate of ocular injury in this community.
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First Report of a Begomovirus Associated with Tomato Yellow Leaf Curl Disease in Ethiopia. PLANT DISEASE 2006; 90:974. [PMID: 30781051 DOI: 10.1094/pd-90-0974a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
During December 2003, severe leaf yellowing, leaf curling, and stunting symptoms were observed in tomato (Lycopersicon esculentum) plantings in Melkassa (1,550 m above sea level), Ethiopia. Eleven symptomatic samples were collected and tested for the presence of a begomovirus using polymerase chain reaction (PCR) with the begomovirus-specific degenerate primer pair PAL1v1978/PAR1c715 (3). Samples were also tested for Cucumber mosaic virus (CMV), Potato virus Y (PVY), Tobacco etch virus (TEV), Pepper veinal mottle virus (PVMV), and Tomato mosaic virus (ToMV) using enzyme-linked immunosorbent assay (ELISA). All samples were negative for CMV, PVY, TEV, PVMV, and ToMV. However, the expected 1.4-kb PCR product for begomoviruses was obtained from all samples. DNA-B and DNA-beta were not detectable using PCR with the DNA-B specific primer pairs DNABLC1/DNABLV2 and DNABLC2/ DNABLV2 (2) and the DNA-beta primer pair Beta01/Beta02 (1), respectively. The 1.4-kb PCR product of one sample was cloned and sequenced. On the basis of the sequence of the 1.4-kb DNA product, specific primers were designed to complete the DNA-A sequence. The DNA-A consisted of 2,785 nucleotides (GenBank Accession No. DQ358913) and was found to contain the six predicted open reading frames (ORFs V1, V2, C1, C2, C3, and C4). A BLAST analysis was conducted with geminivirus sequences available in the GenBank database at the National Center for Biotechnology Information (Bethesda, MD), and DNAMAN software (Lynnon Corporation, Quebec, Canada) was used for further comparisons. The DNA-A sequence of the virus associated with yellow leaf curl disease of tomato from Ethiopia showed highest sequence identity (92%) with Tomato yellow leaf curl Mali virus (TYLCMLV; GenBank Accession No. AY502934). On the basis of the DNA-A sequence comparison and the ICTV demarcation of species at 89% sequence identity, the Ethiopian virus is a provisional strain of TYLCMLV described from Mali. To our knowledge, this is the first report of a begomovirus associated with tomato yellow leaf curl disease in Ethiopia. References: (1) R. W. Briddon et al. Mol. Biotechnol. 20:315, 2002. (2) S. K. Green et al. Plant Dis. 85:1286, 2001. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993.
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Abstract
This survey was conducted at three sites in Ethiopia. The purpose of the survey was to provide detailed information on donkey use in rural and peri-urban areas. The study revealed that donkeys are indeed of immense value to farmers and merchants, being used almost daily for income-generating activities. Unfortunately, they are rarely given any veterinary attention, they receive no feed supplements and their owners are often unaware of improved saddling techniques that would reduce the back sores their animals suffer from. An extension programme providing donkey owners with information on saddling, feeding and basic health care would improve the animals' productivity and improve the livelihoods of the owners.
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Field evaluation of a fast anti-Leishmania antibody detection assay in Ethiopia. Trans R Soc Trop Med Hyg 2006; 100:48-52. [PMID: 16203020 DOI: 10.1016/j.trstmh.2005.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Revised: 07/01/2005] [Accepted: 07/06/2005] [Indexed: 10/25/2022] Open
Abstract
A fast agglutination screening test (FAST) for the detection of Leishmania antibodies in human serum samples was evaluated under harsh field conditions in northern Ethiopia. Test performance was compared with a standard serological test, namely the direct agglutination test (DAT), and with parasitology. In total, 103 suspected cases were recruited for the study. Based on parasitological examination, 49 patients were confirmed of having visceral leishmaniasis (VL) and the other 54 suspected cases were parasitologically negative. Field evaluation of FAST was possible in blood samples of 89 patients. FAST had 4 false negative results and 13 false positive results. DAT had 2 false negative results and 20 false positive results. A good degree of agreement (86.9%) was observed between FAST and DAT (kappa value 0.73). In this field-based evalauation, the sensitivity and specificity of FAST were found to be 91.1% (95% CI 77.9-97.1) and 70.5% (95% CI 54.6-82.8), respectively, compared with 95.3% (95% CI 82.9-99.2) and 62.3% (95% CI 47.9-74.9) for DAT. FAST had a high predictive value of a negative test, demonstrating that FAST could be utilised to exclude rapidly non-VL patients from a large population of suspects with fever and splenomegaly in endemic areas.
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Technology transfer pathways and livelihood impact indicators in central Ethiopia. Trop Anim Health Prod 2005; 37 Suppl 1:101-22. [PMID: 16335074 DOI: 10.1007/s11250-005-9011-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A survey was conducted in central Ethiopia to elicit information on existing and potential dissemination pathways for technical information on donkey husbandry. A detailed socio-economic survey was also conducted to provide background information on the people and the region, and livelihood indicators were drawn out at the same time. The results showed that there are many opportunities for group dissemination by making use of existing social networks. There are also opportunities for dissemination through extension agents, farmer groups and radio broadcasting.
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Abstract
The melanocortin receptors are peptide binding G-protein coupled receptors that play a role in important physiological functions such as energy balance, inflammatory processes and several aspects of reproduction. In this study, we synthesised 11 new linear MSH analogues and tested their binding to the human MC receptors (MC1, MC3, MC4 and MC5) expressed in COS cells. Our results show that introduction of Asp in position 4 similarly affects the binding to the MC1, MC4 and MC5 receptors, but drastically lowers the binding to the MC3 receptor. Arg(5) substitution shows relatively high affinity for the MC4 receptor, while the results also give further support for specific importance of His(6) for the MC1 receptor. Introduction of Asp in position 10, mimicking gamma-MSH, decreased the affinity for the MC3 receptor in similar manner as for the MC4 receptor, suggesting that there are important differences in the binding conformation of gamma-MSH and NPD-MSH. Our results provide further information about the ligand binding requirements for each of the MC receptor subtypes, and highlights differential influence of the core residues in the MSH peptides. The data set also provides useful information for further calculations and modeling of MC receptor binders.
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Relationships between reticular contractions and digesta passage in steers consuming alfalfa hay and barley straw combinations ad libitum. J Anim Sci 1993; 71:3043-51. [PMID: 8270526 DOI: 10.2527/1993.71113043x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A Latin square design experiment was conducted to determine changes in voluntary feed intake, passage of digesta from the ruminoreticulum, and changes in frequency, duration, and amplitude of reticular contractions in four Hereford crossbred steers (474 +/- 10 kg) fed diets consisting of different combinations of alfalfa hay and barley straw. Diets consisted of 1) 100% straw, 2) 67% straw and 33% hay, 3) 33% straw and 67% hay, and 4) 100% hay. The diets were offered at 110% of ad libitum intake. Intakes of DM, OM, and lignin decreased linearly (P = .009, .011, and .003, respectively) with increased dietary straw, whereas diet did not affect intakes of NDF. Daily flows of DM, cell-wall components, and total contents at the duodenum decreased linearly with increased percentage of straw in the diet. Total digesta and fluid in the rumen increased linearly (P = .03 and .02) with increased straw content in the diet. Diet did not affect mean characteristics of reticular contractions. However, flow of total digesta through the proximal duodenum per contraction, per minute, and per centimeter of Hg amplitude of contraction decreased linearly (P = .01 and .02), whereas flow per centimeter of Hg tended to decrease (P = .08) with increased percentage of straw in the diet. Similarly, the flow of NDF through the proximal duodenum per reticular contraction and per minute of contraction decreased linearly (P = .006 and .03) as the percentage of straw increased in the diet. However, when confounding effects of DMI were removed, the characteristics of reticular contractions were not related to DM and NDF flow at the duodenum.(ABSTRACT TRUNCATED AT 250 WORDS)
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Expression of 5-HT1C receptors in transfected MDCK cells is functionally and anatomically asymmetric. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 265:C193-200. [PMID: 8338130 DOI: 10.1152/ajpcell.1993.265.1.c193] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Madin-Darby canine kidney (MDCK) cells were transfected with the cDNA for the rat 5-HT1C receptor (pMV7-SR1c) using electroporation. Cells that survived G418 selection medium were loaded with indo-1 and run through a fluorescence-activated cell sorter (FACS); 10% responded to serotonin (5-HT) with an increase in intracellular Ca2+ concentration ([Ca2+]i). Responding cells were separated with the FACS, grown to confluence, and resorted two more times until a clone of 100% respondents was obtained (SR-MDCK). In SR-MDCK cells grown on porous filters, [Ca2+]i increased only when 5-HT was applied to the basolateral membrane (change in [Ca2+]i = 190 +/- 43 nM); there was no response of [Ca2+]i to apical application of 5-HT. The asymmetric response to 5-HT was likely due to targeting of 5-HT1C receptors exclusively to the basolateral membrane of SR-MDCK cells; 125I-labeled lysergic acid diethylamide binding sites, a marker of high-affinity 5-HT receptors, were located only in the basolateral membrane. These experiments demonstrate that epithelial cells can be stably transfected to express G protein-linked, calcium-mobilizing receptors and that the receptors may be targeted asymmetrically to specific domains of the plasma membrane.
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Carbachol increases basolateral K+ conductance in T84 cells. Simultaneous measurements of cell [Ca] and gK explore calcium's role. J Gen Physiol 1990; 96:1271-85. [PMID: 2126802 PMCID: PMC2229035 DOI: 10.1085/jgp.96.6.1271] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
To explore the role of calcium in mediating the action of carbachol in chloride-secreting epithelia, we simultaneously measured intracellular free [Ca] ([Ca]i) and the potassium conductance (gK) of the basolateral membrane in T84 cells grown on collagen-coated filters. [Ca]i was measured with fura-2 and fluorescence microscopy and expressed as a relative value ([Ca]'i) normalized to control. To assess changes in basolateral gK, we measured the short circuit current (Isc) in the presence of luminal amphotericin and a transepithelial mucosa-to-serosa K+ gradient (Germann, W. J., M. E. Lowy, S. A. Ernst, and D. C. Dawson. 1986. J. Gen. Physiol. 88:237-251). Treatment of the monolayers with carbachol resulted in a parallel increase and then decrease in [Ca]'i and gK. The carbachol-induced changes in gK appeared to be dependent on the increase in [Ca]i because stimulation of gK was significantly diminished when the hormone-induced increase in [Ca]'i was blunted, either by loading the cells with BAPTA or by reducing the extracellular [Ca]. The carbachol-stimulated increase in gK appeared to be the direct result of the increase in steady-state [Ca]'i. The changes in gK and [Ca]'i after stimulation with carbachol were correlated and ionomycin also increased gK and [Ca]'i in a parallel manner. The carbachol-induced delta gK per delta[Ca]'i, however, was greater than that after ionomycin. Because ionomycin and carbachol appear to open the same channel, a conclusion based on inhibitor and selectivity experiments, carbachol may have a second action that amplifies the effect of calcium on gK.
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Abstract
Transgenic constructs containing the murine L-myc gene under the control of the immunoglobulin transcriptional enhancer element (Emu) are expressed at unexpectedly high levels in thymocytes and proliferating T cells compared with cells from bone marrow and proliferating B cells. In contrast, double transgenic animals bearing constructs containing the L- and N-myc genes similarly linked to the Emu element maintain preferential L-myc expression in T cells but express the N-myc transgene preferentially in B cells. These results indicate that the L-myc gene contains elements that act in concert with the Emu element to allow preferential expression in T lineage cells. In correspondence to the expression pattern, Emu-L-myc transgenic mice show expanded thymic cortices and irregularly formed splenic follicles with expanded T cell areas. Moreover, the percentage of thymocytes positive for the surface marker 1C11, which defines thymic progenitor cells, activated T cells and preleukemic T cells, is dramatically raised in transgenic mice compared with normal littermates. Emu-L-myc transgenic animals are predisposed to clonal lymphoid tumors, most of which are T cell lymphomas. The relative incidence, latency period, and degree of malignancy of Emu-L-myc tumors compared with Emu-N- or c-myc tumors is consistent with a lower oncogenic potential of the L-myc gene. However, the Emu-L-myc tumors do not express detectable levels of endogenous myc family genes indicating that the L-myc protein can substitute for c- or N-myc in the generation and growth of lymphoid neoplasms.
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IgH enhancer-mediated deregulation of N-myc gene expression in transgenic mice: generation of lymphoid neoplasias that lack c-myc expression. EMBO J 1989; 8:1121-8. [PMID: 2501083 PMCID: PMC400923 DOI: 10.1002/j.1460-2075.1989.tb03482.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have generated transgenic mouse lines that carry one of three different constructs in which the murine N-myc gene is expressed under the control of the immunoglobulin heavy chain transcriptional enhancer element (E mu-N-myc genes). High-level expression of the E mu-N-myc transgenes occurred in lymphoid tissues; correspondingly, many of these E mu-N-myc lines reproducibly developed pre-B- and B-lymphoid malignancies. The E mu-N-myc transgene also appeared to participate in the generation of a T cell malignancy that developed in one E mu-N-myc mouse. These tumors and cell lines adapted from them expressed exceptionally high levels of the E mu-N-myc transgene; the levels were comparable to those observed in human neuroblastomas with highly amplified N-myc genes. In contrast, all of the E mu-N-myc cell lines had exceptionally low or undetectable levels of the c-myc RNA sequences, consistent with the possibility that high-level N-myc expression can participate in the negative 'cross-regulation' of c-myc gene expression. Our findings demonstrate that deregulated expression of the N-myc gene has potent oncogenic potential within the B-lymphoid lineage despite the fact that the N-myc gene has never been implicated in naturally occurring B-lymphoid malignancies. Our results also are discussed in the context of differential myc gene activity in normal and transformed cells.
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Differential expression of myc-family genes during development: normal and deregulated N-myc expression in transgenic mice. Curr Top Microbiol Immunol 1988; 141:100-9. [PMID: 3215042 DOI: 10.1007/978-3-642-74006-0_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Abstract
We have determined the nucleotide sequence and transforming activity of the human L-myc gene and a processed L-myc pseudogene (L-myc psi). We demonstrate by cotransformation assays that a 10.6-kb EcoRI fragment derived from a human placental library contains a complete and functional L-myc gene including transcriptional regulatory sequences sufficient for expression in rat embryo fibroblasts. Organization of the L-myc gene was determined by comparing its sequence to those of the L-myc psi gene and an L-myc cDNA clone derived from a human small cell lung carcinoma. Our results show that L-myc has a three-exon organization similar to that of the c-myc and N-myc genes. The putative L-myc gene product consists of 364 amino acids and contains five of the seven homology regions highly conserved between c-myc and N-myc. These conserved regions are located along the entire length of the putative L-myc protein and are interspersed among nonconserved regions. While the putative L-myc gene product is of a smaller size when compared to the c- and N-myc proteins, the relative positions of certain conserved residues occur in corresponding locations along the peptide backbone of the three proteins. In addition, comparison of the human and murine L-myc gene sequences indicate that the relatively large 5' and 3' untranslated regions are evolutionarily conserved, but that these sequences are totally divergent between the L-, c-, and N-myc genes. Finally, we demonstrate that, like the N- and c-myc genes, the L-myc gene can cooperate with a mutant Ha-ras gene to cause malignant transformation of rat embryo fibroblasts in culture. Our analyses clearly prove that L-myc represents a functional member of the myc oncogene family and further delineate structural features that may be important for the common and divergent functions of the members of this gene family.
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Abstract
The myc family of cellular oncogenes contains three well-defined members: c-myc, N-myc and L-myc. Additional structural and functional evidence now suggests that other myc-family oncogenes exist. The overall structure and organization of the c-, N-, and L-myc genes and transcripts are very similar. Each gene contains three exons: encoding a long 5' untranslated leader and a long 3' untranslated region. The proteins encoded by these myc genes share several stretches of significant homology. The conservation of sequences at the carboxyterminus of the L-myc protein suggests that it is also a DNA-binding, nuclear-associated protein. Each myc gene will cooperate with an activated Ha-ras oncogene to cause transformation of primary rat embryo fibroblasts. Characteristics of several new myc-family members are described.
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Abstract
N-myc, a cellular gene bearing homology to the c-myc protooncogene, is frequently amplified and overexpressed in a highly restricted set of related tumors, most notably neuroblastomas and retinoblastomas. We have examined the possibility that N-myc may play a causal role in the genesis of these tumors by defining its ability to transform primary cells in tissue culture. Using an N-myc expression construct capable of producing constitutively deregulated levels of full-length murine N-myc mRNA, we demonstrate that a deregulated N-myc gene can cooperate with the activated Ha-ras oncogene to cause tumorigenic conversion of normal embryonic fibroblasts in a manner indistinguishable from the deregulated c-myc oncogene. Cell lines established from N-myc/ras-transformed foci express high levels of the N-myc gene, and such lines are similar to c-myc/ras transformants in their ability to grow in soft agar and cause tumors in syngeneic rats. These results illustrate that N-myc does encode a c-myc-like transforming activity and that this transforming activity is not specific for the very restricted set of tumors in which N-myc is normally amplified or overexpressed.
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