Evaluación del polimorfismo Arg72Pro de p53 como factor pronóstico del traumatismo craneoencefálico grave y su participación en la construcción de un modelo predictivo / Evaluation of the p53 Arg72Pro polymorphism as a prognostic factor in severe head injury and the inclusion of this indicator in a predictive model

OBJETIVO: Clásicamente se han estudiado variablesfisiológicas para conocer los factores pronósticos en laevolución de los pacientes que han padecido un traumatismocraneoencefálico grave, pero hasta hace poco tiempono se pensaba que los factores genéticos pudieraninfluir. El objetivo principal del estudio fue elaborar unmodelo de regresión logística que agrupara parámetrosfisiológicos y el polimorfismo genético Arg72Pro de p53,ya que éste puede condicionar la muerte neuronal porapoptosis.MATERIAL Y MÉTODO: Incluimos en el estudio 90pacientes que ingresaron en la Unidad de Reanimacióncon traumatismo craneoencefálico grave. Se excluyeronaquellos con déficit neurológico previo. Se registraronlas variables clínicas y se analizó el polimorfismoArg72Pro de p53 mediante amplificación por PCR(Polymerase Chain Reaction) de ADN sanguíneo. La evoluciónneurológica se valoró con la Glasgow OutcomeScale. Posteriormente se elaboró un modelo de regresiónlogística con fines predictivos con aquellas variablesrelevantes (que resultaron ser sexo, edad, peor Glasgow,APACHE II, tamaño de las pupilas, reactividad de laspupilas, hemorragia subaracnoidea, número de días deestancia en reanimación, número de días con ventilaciónmecánica y aparición de hipotensión arterial precoz), asícomo el polimorfismo genético Arg72Pro de p53.RESULTADOS: El polimorfismo Arg/Arg fue un predictorindependiente de mala evolución (OR: 3,55; IC del95%: 1,11-11,32; p=0,032). El modelo seleccionado incluyólas variables edad, polimorfismo genético, reactividadpupilar y escala de Glasgow, cuyo poder de discriminaciónes adecuado [sensibilidad 82,3% (IC del 95% 72,8-91,8) y especificidad 78,6% (IC del 95% 63,4-93,8)], presentandoun 81,1% de clasificaciones correctas...(AU)

BACKGROUND AND OBJECTIVE: Physiologic variableshave traditionally been studied as prognostic factors insevere head injury. Until recently it was not thought thatgenetic factors might play a role. The main objective ofthis study was to construct a logistic regression modelincluding physiologic variables and the p53 Arg72Propolymorphism, which can promote neuron deaththrough apoptosis.MATERIAL AND METHODS: We included 90 patientsadmitted to the postoperative recovery unit with severehead injury. Patients with previous neurologic deficitswere excluded. Clinical variables were recorded. Thep53 Arg72Pro polymorphism was analyzed using polymerasechain reaction of DNA in blood. Neurologic outcomewas assessed on the Glasgow Outcome Scale. Apredictive logistic regression model was then constructedbased on relevant candidate variables (sex, age, poorGlasgow score, the Acute Physiology and ChronicHealth Evaluation II score, pupil size, pupil reactivity,subarachnoid hemorrhage, number of days in the recoveryunit, number of days on mechanical ventilation, andthe early development of hypotension) in addition to thep53 Arg72Pro polymorphism.RESULTS: The Arg/Arg polymorphism was an independentpredictor of poor outcome (odds ratio, 3.55;95% confidence interval [CI], 1.11-11.32; P=.032). Theselected model (including the variables age, gene polymorphism,pupil reactivity, and Glasgow score) had funcioadequatediscriminatory power (sensitivity 82.3%, 95%CI 72.8%-91.8%; specificity 78.6%, 95% CI 63.4%-93.8%), classifying 81.1% of the patients correctly. Thep53 Arg72Pro polymorphism, along with pupil reactivity,age and Glasgow score, is useful in a predictivemodel of good or poor outcome on discharge after headinjury(AU)

[Evaluation of the p53 Arg72Pro polymorphism as a prognostic factor in severe head injury and the inclusion of this indicator in a predictive model]. / Evaluación del polimorfismo Arg72Pro de p53 como factor pronóstico del traumatismo craneoencefálico grave y su participación en la construcción de un modelo predictivo.

BACKGROUND AND OBJECTIVE: Physiologic variables have traditionally been studied as prognostic factors in severe head injury. Until recently it was not thought that genetic factors might play a role. The main objective of this study was to construct a logistic regression model including physiologic variables and the p53 Arg72Pro polymorphism, which can promote neuron death through apoptosis. MATERIAL AND METHODS: We included 90 patients admitted to the postoperative recovery unit with severe head injury. Patients with previous neurologic deficits were excluded. Clinical variables were recorded. The p53 Arg72Pro polymorphism was analyzed using polymerase chain reaction of DNA in blood. Neurologic outcome was assessed on the Glasgow Outcome Scale. A predictive logistic regression model was then constructed based on relevant candidate variables (sex, age, poor Glasgow score, the Acute Physiology and Chronic Health Evaluation II score, pupil size, pupil reactivity, subarachnoid hemorrhage, number of days in the recovery unit, number of days on mechanical ventilation, and the early development of hypotension) in addition to the p53 Arg72Pro polymorphism. RESULTS: The Arg/Arg polymorphism was an independent predictor of poor outcome (odds ratio, 3.55; 95% confidence interval [CI], 1.11-1132; P = .032). The selected model (including the variables age, gene polymorphism, pupil reactivity, and Glasgow score) had adequate discriminatory power (sensitivity 823%, 95% CI 72.8%-91.8%; specificity 78.6%, 95% CI 63.4%-93.8%), classifying 81.1% of the patients correctly. The p53 Arg72Pro polymorphism, along with pupil reactivity, age and Glasgow score, is useful in a predictive model of good or poor outcome on discharge after head injury.

VHL protein alterations in sporadic renal cell carcinoma.

AIMS: The vhl gene is a tumour suppressor gene implicated in renal tumorigenesis in both familial and sporadic renal cell carcinoma (RCC). Alterations in the gene may modify its suppressor function and allow the formation of renal tumours. The purpose of this study was to determine the existence of vhl gene mutations in renal tumour tissue among patients with sporadic RCC and to assess the effects on the structure of the VHL protein. MATERIALS AND METHODS: This was an observational, analytical and descriptive study of 96 patients who had undergone surgery for sporadic RCC. In surgical specimens of tumour tissue, the three exons of the vhl gene were amplified by polymerase chain reaction and subjected to automatic sequencing. The consequences of the mutations detected on the VHL protein were analysed, taking into account the physical and chemical properties of the amino acids changed by the mutations, the location of the alterations in the protein sequence, the degree of conservation throughout evolution, and prediction of the secondary structure of the protein. RESULTS: In total, 22 vhl gene mutations were detected in 21 (21.9%) patients; in particular, 13 exonic point mutations consisting of 11 sense mutations, one silent mutation and one missense mutation, plus five exon deletions and one insertion. The remaining three were intronic mutations. All changes occurred in protein functional domains and in regions that have been well conserved throughout evolution. Two-thirds of the intronic mutations were considered relevant for protein function. Among the mutations detected, 72.7% were considered capable of compromising the VHL protein suppressor function. CONCLUSIONS: Mutations in the vhl gene result in amino acid changes in the protein that usually occur at important functional sites that have been conserved throughout evolution and where the binding domains for other proteins are located and exert their suppressor function.

p53 Gene mutations in superficial bladder cancer.

OBJECTIVES: To assess the presence of p53 gene mutations in superficial tumors of the urinary bladder (transitional cell carcinoma) and their relationship to classic prognostic factors for cancer recurrence and progression. To analyze the implication of these mutations on the P53 protein structure. MATERIALS AND METHODS: Observational, cross-sectional study of 90 consecutive patients, 60 with superficial transitional cell carcinoma (pTa and pT1) and 30 without neoplastic disease (control group). Samples of bladder tumor and control normal mucosa were analyzed by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) to detect p53 mutations in exons 5-9. Automatic sequencing was used to characterize the mutations and their effect on the P53 protein was analyzed. Bivariate analysis was used to assess the association with other prognostic factors. RESULTS: PCR-SSCP found no mutations in any control group patient, whereas 38.3% of patients with superficial transitional cell carcinoma had one or more mutations in the exons analyzed. Thirty mutations were sequenced; all were point mutations and 86.67% were considered relevant for the P53 structure. A total of 93.3% of the mutations were located in highly conserved regions and 73.3% in mutational hot spots. The highest cell differentiation grades and pT1 stage were associated with a higher incidence of p53 gene mutations. Previous recurrences and other tumor-related histological variables were not associated with a higher percentage of mutations. CONCLUSION: Mutations at p53 did not appear in healthy bladder mucosa and were significantly more frequent in pT1 and high-grade (G-II and G-III) tumors. All mutations detected were point mutations and most caused considerable P53 structural abnormalities, implying major repercussions on P53 function. These data suggest that certain p53 mutations may have prognostic value, even though they were not associated with other classic recurrence and tumor progression parameters. Future analyses of the progress of patients with superficial bladder transitional cell carcinoma and mutated p53 will help clarify this aspect.

Prognostic implications of p53 gene mutations in bladder tumors.

PURPOSE: Alterations in the p53 gene related to neoplastic progression were studied in tumor tissue samples from patients with transitional cell carcinoma and correlated with classic staging parameters. On this basis, biological characterization of the tumor was performed to establish subgroups of patients at high risk and those with a more favorable prognosis. MATERIALS AND METHODS: This observational, analytical and cross-sectional study included 115 patients divided into 4 homogeneous groups of 1-control, 2-primary superficial transitional cell carcinoma, 3-recurrent superficial transitional cell carcinoma, and 4-infiltrative transitional cell carcinoma. DNA was obtained from tumor tissue samples and polymerase chain reaction-single strand conformational polymorphism analysis was performed on exons 5 to 9 of the p53 gene. Samples showing mutations were submitted to automatic sequencing. Statistics included bivariate analysis and logistic regression. RESULTS: Of the tumors the 63.8% were superficial and 37.2% were infiltrative transitional cell carcinoma. Of the infiltrative tumors 23.5% (8 of 34) resulted from recurrent transitional cell carcinoma. Mutations were found in samples from 46.8% of patients, all with bladder tumors. There was a trend toward increasing appearance of mutations as the size of the tumor, number of tumor implants, degree of dedifferentiation and stage of local infiltration increased. The presence of mutations in p53 was 2.5 times greater in infiltrative tumors than in low stage and 4.3 times greater in moderate to high grade than in low grade tumors. All mutations found were point mutations and 79.25% provoked severe alterations in protein structure. CONCLUSIONS: Mutations in the p53 gene are mainly point mutations that aggregate in hot spots, and provoke genetic instability and substantial changes that alter p53 function, implying a trend to tumor progression and dissemination (with a greater proportion of mutations in high stage high grade tumors). Since a large percentage of bladder tumors are under staged, analysis of p53 gene mutations could be useful as a factor for prognosis and therapeutic decisions.