Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Reverse Survival Method”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2002

[Effect of benzo[a]pyrene on DNA damage and expression of genes involved in nucleotide excision repair in lung cancer cells].

OBJECTIVE: To investigate the effect of benzo[a] pyrene(BaP) on DNA damage and expression of genes involved in nucleotide excision repair[xeroderma pigmentosum group B, C, G(XPB, XPC, XPG) and excision repair cross-complementing 1 (ERCC1)] in lung cancer A549 cells. METHODS: Cell survival was measured using MIT metabolic viability assay. Single cell gel assay was applied to determine the DNA damage and repair. The level of gene expression was measured by reverse transcription-polymerase chain reaction. RESULTS: The cell survival decreased from 95.0% to 70.0% after 24 h treatment with BaP of varying concentration ranging 0.625-20.000 mumol/L. The cell survival decreased to 87.0% and 73.0% respectively after 12 h and 24 h treatment with 10 mumol/L BaP, with DNA damage gradually elevated. At 12 h after 24 h treatment, the cell survival further decreased to 59.0% and DNA damage became most serious. At 24 h after 24 h treatment, cell survival recovered to 71.0%, and damaged DNA was repaired gradually. XPB and XPC gene expression increased to 4.5-fold and 11.2-fold respectively compared with basal level at 24 h treatment or 12 h after 24 h treatment with 10 mumol/L BaP respectively. However, ERCC1 and XPG gene expression was inhibited in 24 h treatment period, then recovered gradually after treatment. CONCLUSION: Benzo[a]pyrene could lead to DNA damage and expression level change of genes involved in nucleotide excision repair in lung cancer A549 cells.

Benzo(a)pyrene↗
PubMed2005

[Identification of the related gene of mouse tolerant to exposure to perfluoroisobutylene by DDRT-PCR].

OBJECTIVE: The mice surviving acute exposure to low dose of perfluoroisobutylene (PFIB) could tolerant to lethal dose of PFIB. Discovering the gene related with the tolerance would be significant to find preventive agents for PFIB. METHODS: By static exposure to PFIB for 3 times, the survival animals could tolerate to lethal dose of PFIB. Three anchoring primers and 4 arbitrary primers were applied in differential display reverse transcription PCR (DDRT-PCR) of lung tissues and the products were analyzed by sequencing PAGE and silver staining. The differential DNA fragments were cloned and sequenced. RESULTS: There were obvious differences of gene expression between control and tolerant animals. Three expressed sequence tags (EST) have been cloned and sequenced,which were homologous to some mouse gene in Genbank. CONCLUSION: Specific gene up-regulation might be the cause of tolerance to PFIB, and they are very important to clarity the tolerant mechanisms to PFIB.

Animals↗
PubMedDate not supplied

An 18-year retrospective survival study of full crowns with or without posts.

PURPOSE: This study of full crowns investigated long-term survival in relationship to biologic and technical variables. MATERIALS AND METHODS: A total of 1,037 full crowns in 456 patients, made in an undergraduate university clinic, were evaluated over an 18-year period. All patients were offered a supportive maintenance program. Failures of full crowns were classified as irreversible (loss of full crown and/or tooth) or reversible (full crown intact after conservative treatment) complications and as biologic or technical/patient-related failures. RESULTS: The Kaplan-Meier survival rate after 18 years was 78%. No statistically significant differences were found between restorations in the maxilla and mandible (P= .150); between restorations on molars, premolars, and anterior teeth (P = .671); and between restorations on posts and cores compared to restorations without posts and cores (P = .602). For the surviving restorations, the improved plaque score over time was statistically significant (P = .001). Biologic failures (66.4%) resulting in removal were more common than technical and patient-related failures (33.6%). Caries was the most frequent reason for failure (irreversible complication). CONCLUSION: The survival of full crowns made in an undergraduate university clinic during an 18-year period is comparable to the results published by university departments or private practitioners. Plaque scores and bleeding on probing were not directly related to failures. Occurrence of a previously reversible complication is a predicting factor for an irreversible complication. A reversible complication within the first 2 years will probably lead to an early irreversible complication.

Adolescent↗
PubMed2002

[Influence of warm ischemia injury on energy metabolism and survival of liver graft in rats].

OBJECTIVES: To investigate the energy metabolism and post transplantation survival of liver graft under different warm ischemia times (WIT) in rats and determine the maximum limitation of liver graft to warm ischemia. METHODS: According to WIT, the rats were randomized into 7 groups, and WIT were 0, 10, 15, 20, 30, 45, 60 minutes respectively. The indexes of energy metabolism were measured by reversed-phase high performance liquid chromatography (HPLC) and all liver graft specimens were subjected to ultrastructural observation. After orthotopic liver transplantation (OLTx), the recovery of energy metabolism of liver graft after 24, 48 hours and the rats' survival were observed. RESULTS: The levels of adenosine triphosphate (ATP) and energy charge (EC) decreased gradually after different WIT in a time-dependent manner, and especially significant within 30 minutes. The levels of ATP and EC of liver grafts were largely recovered after 24 hours of OLT within 30 minutes of warm ischemia, partially recovered after 48 hours of OLT with 45 minutes of warm ischemia and hardly recovered even after 48 hours of OLT with 60 minutes of warm ischemia. The rat survival time after OLT was not significantly different within 30 minutes of WIT, while the long-term survival was insulted with 45 and 60 minutes of WIT. CONCLUSIONS: The levels of ATP and EC after OLT may be the important criteria to evaluate the quality of liver graft. WIT of liver graft is closely related to both the recovery of hepatic energy metabolism and the liver graft survival.

Adenosine Triphosphate↗
PubMed2005

Clinical and molecular prognostic factors in operable laryngeal cancer.

Many factors affect the prognosis in operable laryngeal squamous cell carcinoma (LSCC). Many clinical factors have been implicated in tumor recurrence and poor survival of the patients. The aim of the present study is to investigate the demographic, clinical and histological characteristics as prognostic factors. Moreover, our aim is to analyze the role of modern molecular biomarkers in the prognosis of patients with LSCC. One hundred patients with operable laryngeal carcinoma underwent surgery as primary treatment between April 1999 and April 2002. Ninety-four of them were men and 6 women, with a median age of 62 years (39-77). All demographic data of the patients were recorded. Staging of the tumor revealed 20 cases with T2 cancer, 46 cases with T3 and 34 cases with T4, while N classification included 91 patients with N0 tumor, 3 with N1 and 6 with N2. Among the 100 cases, 47 were located in the glottis, 46 in the supraglottic region and 7 were transglottic. Histology grading revealed 35 cases of grade G1, 50 cases of G2 and 15 cases of G3. Postoperatively, all patients were followed regularly for the possibility of tumor relapse, with a median follow-up period of 40.2 months (4.8-58.4). During the operation, a tissue specimen was collected from the tumor. The specimens were used for RNA and DNA extraction. Isolated RNA was used to investigate the expression of wt-p53, bcl-2, VEGF and EGFR by the reverse transcriptase PCR method (RT-PCR) using specific primers, while genomic DNA was used for the detection of EBV and HPV (16/18 subtypes) by the consensus primer-mediated polymerase chain reaction method (PCR). All data such as tumor recurrence and survival were recorded. Statistical analysis was performed using the SPSS and STATA statistical packages in order to investigate the role of all clinical and molecular factors and their combinations as significant prognostic markers. The tumor recurrence rate was 31%, while the tumor associated death rate was 27% and total death rate 30%. Univariate analysis for overall survival showed significance for the T stage, TNM stage and site of the tumor. Univariate analysis for the time to progression showed significance for the T stage, N stage, TNM stage, site of the tumor and tumors simultaneously positive for EGFR and VEGF, while EGFR expression was borderline insignificant. Multivariate analysis revealed TNM stage as the only significant factor for overall survival, and TNM stage, site of the tumor and EGFR expression as significant factors for time to progression. The molecular biomarkers EGFR and VEGF have a prognostic significance in laryngeal cancer in addition to the established clinical prognostic factors such as the stage and site of the tumor. These markers, apart from their role in carcinogenesis, seem to play an important role in tumor relapse.

Adult↗
PubMed1999

Parametric analysis for matched pair survival data.

Hougaard's (1986) bivariate Weibull distribution with positive stable frailties is applied to matched pairs survival data when either or both components of the pair may be censored and covariate vectors may be of arbitrary fixed length. When there is no censoring, we quantify the corresponding gain in Fisher information over a fixed-effects analysis. With the appropriate parameterization, the results take a simple algebraic form. An alternative marginal ("independence working model") approach to estimation is also considered. This method ignores the correlation between the two survival times in the derivation of the estimator, but provides a valid estimate of standard error. It is shown that when both the correlation between the two survival times is high, and the ratio of the within-pair variability to the between-pair variability of the covariates is high, the fixed-effects analysis captures most of the information about the regression coefficient but the independence working model does badly. When the correlation is low, and/or most of the variability of the covariates occurs between pairs, the reverse is true. The random effects model is applied to data on skin grafts, and on loss of visual acuity among diabetics. In conclusion some extensions of the methods are indicated and they are placed in a wider context of Generalized Estimation Equation methodology.

Epidemiologic Methods↗
PubMed2004

Inducible, reversible, and stable RNA interference in mammalian cells.

RNA interference is a powerful genetic approach for efficiently silencing target genes. The existing method of gene suppression by the constitutive expression of short hairpin RNAs (shRNAs) allows analysis of the consequences of stably silencing genes but limits the analysis of genes essential for cell survival, cell cycle regulation, and cell development. We have developed an inducible U6 promoter for synthesis of shRNAs in both human and murine cells. Cells containing stably integrated shRNA expression constructs demonstrate stringent dosage- and time-dependent kinetics of induction with undetectable background expression in the absence of the inducer ecdysone. Inducible suppression of human p53 in glioblastoma cells shows striking morphological changes and defects in cell cycle arrest caused by DNA damage, as expected. Remarkably, the inducibility is reversible after withdrawal of the inducer, as observed by reappearance of the protein and a restoration of the original cell phenotype. Inducible and reversible regulation of RNA interference has broad applications in the areas of mammalian genetics and molecular therapeutics.

Animals↗
PubMed2004

Mammaglobin is associated with low-grade, steroid receptor-positive breast tumors from postmenopausal patients, and has independent prognostic value for relapse-free survival time.

PURPOSE: The tumor mRNA expression levels of mammaglobin, a novel breast-specific and breast cancer-associated marker, were correlated with disease outcome in 280 patients with primary breast cancer. PATIENTS AND METHODS: Mammaglobin expression levels were assessed by quantitative reverse transcriptase polymerase chain reaction in frozen tumor tissue from breast cancer patients with a median age of 60 years (range, 30 to 88 years) and a median follow-up of 85 months (range, 2 to 169 months). RESULTS: High expression levels were associated with low-grade tumors (P =.018), with positive estrogen and progesterone receptor status (P <.001), and postmenopausal status (P =.010). In the analysis of all patients, low tumor mammaglobin expression levels predicted an early relapse both in Cox univariate (hazard ratio [HR], 0.52; 95% CI, 0.34 to 0.79; P =.002) and multivariate regression analyses corrected for the traditional prognostic factors (HR, 0.55; 95% CI, 0.35 to 0.88; P =.012). The association of mammaglobin expression with the rate of relapse was particularly favorable in patients who received adjuvant tamoxifen treatment (HR, 0.35; 95% CI, 0.17 to 0.71; P =.004). CONCLUSION: These results demonstrate that the assessment of the tumor mRNA expression level of the breast-specific protein mammaglobin could be useful to stratify patients for individual adjuvant treatment strategies.

Adult↗
PubMed1998

Quantitative analysis of the expression of apoptosis-related genes.

BACKGROUND: The development and subsequent introduction of current molecular biology techniques allows the elucidation of some of the mechanisms of the programmed cell death (apoptosis). The overexpression of the genes directly (B-cell leukemia/lymphoma-2, BCL-2) or indirectly (multidrug resistance gene-1, MDR1) involved in the suppression of apoptosis, as well as the low-level expression of their antagonists (BCL-2 associated X-protein, BAX) result in longer survival and the development of drug resistance in malignant cells. AIM: The objective of this study was to design our own appropriate primers and to synthesize internal RNA standards and this way to evaluate the rate of expression of the MDR1, BCL-2 and BAX genes using a competitive reverse transcription and polymerase chain reaction (cRT-PCR). MATERIAL AND METHODS: Peripheral blood or bone marrow aspirates from 5 patients and 3 healthy controls were used for RNA extraction. Competitive RT-PCR was employed utilizing the constructed specific primers and synthesized internal RNA standards. Following electrophoresis, the PCR products stained with ethidium bromide were evaluated on the "Gel Doc 1000TM" video image system. RESULTS: The constructed primers specific for each of the three genes and synthesized internal RNA standards with a suitable deletion allow receiving the yield of well-separated competitive amplicons. The measured band's intensity of light and the calculated standard/patient ratio were employed in the analysis of the MDR1, BCL-2 and BAX gene expression. CONCLUSIONS: Competitive RT-PCR is a non-radioactive and comparatively rapid molecular biology method suitable for everyday laboratory practice. The possibility for simultaneous evaluation of the expression of several genes could help in the elucidation of some of the mechanisms underlying the prolonged survival of malignant cells.

Apoptosis↗
PubMed2000

Clinical significance of micrometastases in axillary lymph nodes assessed by reverse transcription-polymerase chain reaction in breast cancer patients.

We evaluated the clinical significance of micrometastases in axillary lymph nodes (AxLNs) of breast cancer patients for prediction of prognosis. Archived formalin-fixed paraffin-embedded AxLN specimens from 129 node-negative breast cancer patients diagnosed by routine H&E staining between 1986 and 1990 were subjected to carcinoembryonic antigen-specific reverse transcription-PCR analysis. Micrometastases were detected in 40 of 129 (31.0%) node-negative breast cancer patients. After a median follow-up period of 105.6 months, log-rank test analysis indicated that 10-year disease-free and overall survival rates by Kaplan-Meier methods were significantly better in patients without micrometastases than in patients with micrometastases [disease-free survival, 87.6% versus 66.1% (P = 0.0008); overall survival, 93.7% versus 67.8% (P = 0.0024)]. The presence of micrometastases in AxLNs was revealed by multivariate analyses to be an independent and significant predictor of clinical outcome. The hazard ratio was 3.992 (95% confidence interval, 1.293-12.323; P = 0.0161) for relapse and 4.293 (95% confidence interval, 1.043-17.675; P = 0.0436) for cancer-related death. The molecular staging of AxLNs using reverse transcription-PCR is useful for prediction of clinical outcome in early-stage breast cancer patients and can provide a powerful and sensitive complement to routine histopathological analysis.

Adult↗
PubMedDate not supplied

A 20-year retrospective survival study of fixed partial dentures.

PURPOSE: This study of fixed partial dentures (FPDs) evaluated the long-term efficacy and determined frequencies and causes of failures. MATERIALS AND METHODS: A total of 322 FPDs in 193 patients, fabricated at an undergraduate university clinic, were evaluated over a 20-year period. All patients were invited to participate in a supportive maintenance program. Failures of the FPDs were divided into irreversible complications (loss of FPD/abutment) and reversible complications (FPD intact after conservative treatment) and into biologic and technical/patient-related failures. RESULTS: The Kaplan-Meier survival rate after 20 years was 66.2%. Statistically significant differences in survival rates were found between FPDs without post-and-core abutment teeth as compared to FPDs with at least one post-and-core abutment tooth (P = .002) and for vital abutments versus post-and-core abutments (P = .001), but significant differences were not found between restorations in the maxilla and mandible (P = .27). Caries and loss of retention were the main reasons for failure and accounted for 61% of the failures. CONCLUSION: The survival of FPDs by undergraduate students at a university clinic during a 20-year period was comparable to the results published by university departments or general practitioners. Occurrence of a previously reversible complication is a predictive factor for an irreversible complication later on. A reversible complication within the first 2 years will probably lead to an early irreversible complication.

Adult↗
PubMed2006

Retrospective study of reverse dorsal metacarpal flap and compound flap: a review of 122 cases.

OBJECTIVE: To evaluate the clinical application and discuss the operative indication of the reverse dorsal metacarpal flap and its compound flap on the skin defects of hand. METHODS: From 1990 to 2003, we applied the reverse dorsal metacarpal flap and its compound flap to repair soft tissue defects of fingers in 122 cases, which included 90 cases of the reverse metacarpal flap and 32 cases of its compound flaps with tendon grafts, nerve grafts or bone grafts. Based on the follow-up observations, we analyzed the indications of the reverse metacarpal flap and its compound flaps, the postoperative contours, flap colors and textures in comparison to contralateral fingers retrospectively. RESULTS: In the series of 122 cases, flaps survived and the donor site defects were closed directly. The follow-up period ranged from 1-12 years. The postoperative contours, colors and textures of the flaps and its compound flaps were similar to those of normal fingers, although linear scar remained. According to standards of sense recovery (British Medical Research Council, BMRC), the sense function of the flaps resumed S3 after operation for 1 year. In 10 cases with the tendon defects treated by the flap with tendon grafts, function of flexion-extension of fingers resumed 50%-75% in comparison to the contralateral fingers using the method of measurement of total active motion. In 7 cases with the phalangeal nonunion or bone defects treated by the flap with bone grafts, union occurred after operation for 3 months. CONCLUSIONS: To soft tissue defects on fingers with bone or tendon exposure, the reverse metacarpal flap and its compound flap are a better choice for repairing. The range of repairing is up to the distal interphalangeal joint of fingers. The second dorsal metacarpal artery is more consistent and larger as the choice of vascular pedicle, in comparison with other dorsal metacarpal arteries. Postoperative flap color and texture are similar to normal fingers.

Adolescent↗
PubMed2003

Simvastatin rescues rats from fatal pulmonary hypertension by inducing apoptosis of neointimal smooth muscle cells.

BACKGROUND: Pulmonary vascular injury by toxins can induce neointimal formation, pulmonary arterial hypertension (PAH), right ventricular failure, and death. We showed previously that simvastatin attenuates smooth muscle neointimal proliferation and pulmonary hypertension in pneumonectomized rats injected with the alkaloid toxin monocrotaline. The present study was undertaken to investigate the efficacy of simvastatin and its mechanism of reversing established neointimal vascular occlusion and pulmonary hypertension. METHODS AND RESULTS: Pneumonectomized rats injected with monocrotaline at 4 weeks demonstrated severe PAH at 11 weeks (mean pulmonary artery pressure [mPAP]=42 versus 17 mm Hg in normal rats) and death by 15 weeks. When rats with severe PAH received simvastatin (2 mg x kg(-1) x d(-1) by gavage) from week 11, there was 100% survival and reversal of PAH after 2 weeks (mPAP=36 mm Hg) and 6 weeks (mPAP=24 mm Hg) of therapy. Simvastatin treatment reduced right ventricular hypertrophy and reduced proliferation and increased apoptosis of pathological smooth muscle cells in the neointima and medial walls of pulmonary arteries. Longitudinal transcriptional profiling revealed that simvastatin downregulated the inflammatory genes fos, jun, and tumor necrosis factor-alpha and upregulated the cell cycle inhibitor p27Kip1, endothelial nitric oxide synthase, and bone morphogenetic protein receptor type 1a. CONCLUSIONS: Simvastatin reverses pulmonary arterial neointimal formation and PAH after toxic injury.

Animals↗
PubMed2000

Analysis strategies for longitudinal attachment loss data.

The purpose of this invited review is to describe and discuss methods currently in use to quantify the progression of attachment loss in epidemiological studies of periodontal disease, and to make recommendations for specific analytic methods based upon the particular design of the study and structure of the data. The review concentrates on the definition of incident attachment loss (ALOSS) and its component parts; measurement issues including thresholds and regression to the mean; methods of accounting for longitudinal change, including changes in means, changes in proportions of affected sites, incidence density, the effect of tooth loss and reversals, and repeated events; statistical models of longitudinal change, including the incorporation of the time element, use of linear, logistic or Poisson regression or survival analysis, and statistical tests; site vs person level of analysis, including statistical adjustment for correlated data; the strengths and limitations of ALOSS data. Examples from the Piedmont 65+ Dental Study are used to illustrate specific concepts. We conclude that incidence density is the preferred methodology to use for periodontal studies with more than one period of follow-up and that the use of studies not employing methods for dealing with complex samples, correlated data, and repeated measures does not take advantage of our current understanding of the site- and person-level variables important in periodontal disease and may generate biased results.

Disease Progression↗
PubMed1994

Fetal hemoglobin synthesis in sickle cell anemia: some molecular considerations.

An ability to maintain high levels of fetal hemoglobin (Hb F) has been associated with the amelioration of the clinical severity of the sickle cell disease (SS). Clinical efforts to increase the Hb F level of the patients have, however, yielded variable therapeutic response. In an attempt to further elucidate the underlying molecular basis, in vitro Hb F synthesis was studied in erythroid progenitor (BFU-E) cells obtained from SS patients and their heterozygous (AS) relatives with varying genetic backgrounds. This allows us to study the Hb F biosynthesis pattern uncomplicated by the influence of the preferential survival of "F cells" in vivo. The Hb F levels and the relative concentrations of its constituent gamma globin chains, G gamma and A gamma, were assayed using the reversed phase HPLC method. A percentage increase in the fetal hemoglobin content was observed in the lysates of the erythroid progenitor cells relative to the circulating peripheral blood erythrocyte values in SS patients and their AS relatives with different beta S haplotypes reflecting the intrinsic capacity of fetal hemoglobin synthesis in these subjects. No such increase was observed in the patient with the Mor haplotype. Furthermore, the Hb F synthesized in the BFU-E colonies was more of the adult type, as evidenced by the decrease in the percent G gamma level relative to the corresponding peripheral blood values of the subjects in all the haplotype groups studied. The Mor haplotype was again an exception, synthesizing fetal hemoglobin more of the fetal type.

Anemia, Sickle Cell↗
PubMed2003

The diagnostic and prognostic relevance of human telomerase reverse transcriptase mRNA expression detected in situ in patients with nonsmall cell lung carcinoma.

BACKGROUND: The objectives of this study were to evaluate the diagnostic and prognostic relevance of human telomerase reverse transcriptase (hTERT) detected in situ in patients with nonsmall cell lung carcinoma (NSCLC) and to investigate the possible correlations between hTERT mRNA in NSCLC and the patients' clinicopathologic features, including survival. METHODS: hTERT mRNA was detected by in situ hybridization in 146 samples from patients with NSCLC. The signal intensity of hTERT mRNA expression was evaluated by two independent observers. The expression level was defined subjectively as strong, moderate, or weak. RESULTS: hTERT mRNA was detected mainly in the cytoplasm of tumor cells. It was detected in the cytoplasm of 100% of samples from patients with NSCLC but was not detected in normal lung tissue, except in activated lymphocytes. There was a significant correlation between hTERT mRNA expression and pathologic tumor status, pathologic disease stage (pStage), and Ki-67 labeling index. There was no significant correlation between hTERT mRNA expression and age, gender, pathologic lymph node status (pN), histology, or tumor differentiation. The 5-year survival rates for patients with strong and moderate hTERT mRNA expression levels were 46.9% and 77.9%, respectively; the difference was statistically significant (P = 0.0001). A multivariate analysis of survival using a stepwise procedure revealed that hTERT mRNA expression, pN status, pStage, and age were statistically significant prognostic factors (P = 0.0029, P = 0.0012, P = 0.0237, and P = 0.0496, respectively). CONCLUSIONS: The findings suggested that hTERT mRNA expression may be useful for the diagnosis of NSCLC and also may be an independent prognostic factor for patients with NSCLC.

Adult↗
PubMed2005

Combined high cervical spine and brain stem injuries: a complex and devastating injury in children.

BACKGROUND: In young children, high cervical spine injuries (HCSI) can result in inaugural reversible, cardiac arrest or apnea. We noted in children sustaining such injuries an unusual incidence of associated brain stem injuries and defined a special pattern of combined lesions. METHODS: Children with HSCI surviving inaugural cardiac arrest/apnea were selected for a retrospective analysis of a trauma data bank. Epidemiologic, clinical, and radiological characteristics, and outcome were reviewed and compared with those of the rest of the trauma population with severe neurologic injuries (defined by a Glasgow Coma Scale < 8). RESULTS: Thirteen children with HCSI above the C3 spinal level and inaugural cardiac arrest/apnea were identified and compared with 819 severely head injured children without HSCI. Mean age was 4.7 +/- 2.9 years, and median Glasgow Coma Scale was 3 (3-6) after resuscitation. Initial standard x-ray views missed spine injuries in 6 patients. Spiral computed tomographic (CT) scan showed cervical fracture-dislocations associated with diffuse brain lesions and brain stem injury in all patients. Children with combined lesions had more frequent severe facial and skull base fractures compared with the rest of the population. They also were younger and sustained more frequent severe distracting injury to the neck than the rest of the population. Mortality rate (69%) was 2.6-fold higher than that observed in children without HCSI. In survivors, none demonstrated spinal cord injury resulting in persistent peripheral neurologic deficits, but only one achieved a good recovery. CONCLUSIONS: Combined HCSI and brain stem injuries must be suspected in young children sustaining a severe distracting injury to the craniocervical junction. Early recognition of these catastrophic injuries by systematic spiral cervical spine and brain stem computed tomographic scan evaluation is mandatory.

Algorithms↗
PubMed2000

Construction of a non-tumorigenic rat hepatocyte cell line for transplantation: reversal of hepatocyte immortalization by site-specific excision of the SV40 T antigen.

BACKGROUND/AIMS: Hepatocytes immortalized with a temperature-sensitive SV40 large T antigen (SV40Tag) function as well as primary hepatocytes following transplantation to reverse hepatic encephalopathy and improve survival in rodents with liver failure. The continued presence of SV40Tag in the conditionally immortalized hepatocytes may increase the risk of malignant tumor growth in transplant recipients. METHODS: We immortalized hepatocytes using a recombinant retrovirus containing the gene encoding SV40Tag flanked by loxP recombination target sites. Excision of SV40Tag from immortalized cells could then be accomplished by site-specific recombination with Cre-recombinase. RESULTS: Cells immortalized with this recombinant virus expressed SV40Tag and doubled in number every 48 h. After excision of the gene encoding SV40Tag with Cre-recombinase, cells stopped growing, DNA synthesis fell by 90%, and production of liver-specific mRNAs was either increased or became newly detectable. In addition, the morphology and epithelial cell polarity of the cells became more characteristic of differentiated hepatocytes. To determine their malignant potential, immortalized hepatocytes were transfected to express a second oncogene, activated H-ras. SV40Tag+/H-ras+-immortalized cells were capable of anchorage-independent growth and developed into tumors when injected in severe combined immunodeficiency mice. While Cre-recombinase delivery by recombinant adenovirus infection was not 100% efficient, when SV40Tag excision occurred anchorage-independent growth stopped and tumor formation in immunodeficient mice was abolished. Immortalized hepatocytes also contained the gene encoding herpes simplex virus thymidine kinase and treatment with ganciclovir produced complete regression of established tumors in mice. CONCLUSIONS: These studies extend previous work that indicates that a transplantable hepatocyte cell line could be developed for clinical use.

Animals↗