Ana María Inda

Changes in VEGF expression and DNA synthesis in hepatocytes from hepatectomized and tumour-bearing mice

Transplanted tumours could modify the intensity and temporal distribution of the cellular proliferation in normal cell populations, and partial hepatectomy alters the serum concentrations of substances involved in cellular proliferation, leading to the compensatory liver hyperplasia. The following experiments were designed in order to study the SI (S‐phase index) and VEGF (vascular endothelial growth factor) expression in regenerating liver (after partial hepatectomy) of adult male mice bearing a hepatocellular carcinoma, throughout one complete circadian cycle. We used adult male C3H/S‐strain mice. After an appropriate period of synchronization, the C3H/S‐histocompatible ES2a hepatocellular carcinoma was grafted into the subcutaneous tissue of each animals flank. To determine the index of SI and VEGF expression of hepatocytes, we used immunohistochemistry. The animals were divided into two experimental groups: Group I, control, hepatectomized animals; Group II, hepatectomized tumour‐bearing animals. The statistical analysis of SI and VEGF expression was performed using Anova and Tukey as a postcomparison test. The results show that in the second group, the curve of SI changes the time points for maximum and minimum activity, and the peak of VEGF expression appears before the first group. In conclusion, in the hepatectomized mice, the increases of hepatic proliferation, measured by the SI index, may produce a rise in VEGF expression with the object of generating a vascular network for hepatic regeneration. Lastly, as we have mentioned, in hepatectomized and tumour‐bearing mice, the peak of VEGF expression appears before the one of DNA synthesis.

G2RESTRICTION POINT WITHIN POPULATIONS OF HEPATOCYTES AND TONGUE KERATINOCYTES IN YOUNG, GROWING MICE

The authors studied the effect of either extracts from liver (LE) or the malignant tumour ES2 (TE) or plasma from intact mice (PI) or tumour‐bearing animals (PT) on the mitotic activity of the hepatocytes and tongue keratinocytes in young, growing C3H/s male mice (28±1 days old). Animals standardized for periodicity analysis were injected intraperitoneally with either TE, LE, PI, PT, or saline (S) at 16:00h with 0.01ml of sample/g of body weight and were then killed at (time of day/h post‐injection) 20:00/04, 00:00/08, and 04:00/12. Colchicine (2μg/g) was injected 4h before death. Samples of the liver and tongue from each animal were processed for histology and assessment of mitotic index. The results were expressed as colchicine‐arrested metaphases/1000 nuclei. The TE and LE stimulated the mitotic activity of hepatocytes and tongue keratinocytes. Taking into account the time elapsed between the injections and the measurements made in these light‐dark synchronized animals, we conclude that the increase in mitotic index observed in those tissues stemmed from a reinitiation of cell‐cycle traverse in a subpopulation of G2‐arrested, noncycling cells.

Vascular endothelial growth factor expression along a circadian time span in intact adult mice liver

In the present study we analyzed VEGF-A expression in adult male and female C3H/S mice along a circadian time span. The animals were sacrificed at 00:00, 04:00, 08:00, 12:00, 16:00 and 20:00 h. Samples of the liver from each animal were processed for immunohistochemistry. The VEGF expression index was calculated as positives immunostaining hepatocytes x 100 and analyzed by ANOVA, and the Student–Newman–Keuls Multiple Comparison Test. The results show that in both male and female mice there were significant differences between the values corresponding to all the time points studied. In male mice the values of VEGF expression of 20:00 h are significantly higher than all the others analyzed while in females the value of the 20:00 h was significantly different from the value of the 04:00 h. In conclusion, the hepatocytes of the perivenular areas in the liver of intact adult male and female mice expressed VEGF with a defined circadian rhythm.

Circadian rhythm of VEGF expression in the liver of hepatectomized tumor bearing mice

In this study we analyzed VEGF-C expression in regenerating liver (after partial hepactectomy) of ES2 hepatocellular carcinoma bearing mice, throughout one complete circadian cycle. The animals were sacrificed every 4 h throughout one complete circadian cycle from 26 to 50 h post-hepatectomy. Tumor samples were processed for immunohistochemistry. The expression of VEGF was assessed according to the percentage of immunoreactive cells in a total of 1000 cells (quantitative analysis). The results show that controls and tumor bearing mice have statistical differences at all analysed time points, but the maximun value of VEGF expression of treated animals is significantly higher (p < 0.01) than the control group. We can conclude that when a partial hepatectomy is made with the purpose of eradicating a hepatic tumor, the presence of possible metastasis could release factors related with cellular proliferation that could increase the possibilities of tumoral recidives.

VEGF EXPRESSION IN HEPATECTOMIZED TUMOR-BEARING MICE

The experiments were designed in order to study the VEGF expression in intact (group I), hepatectomized (group II), and hepatectomized-tumor bearing mice (group III) throughout one complete circadian time span. Adult male mice were used for the VEGF expression study. The statistical analysis was performed using analysis of variance (ANOVA). The results showed statistical differences in the VEGF expression between groups I and II, but the most significant differences were found between groups I and III. In conclusion, these expressions have a circadian rhythm in all groups; moreover, in group III, this expression was higher and appeared before than in the others.

Modificaciones de la estructura ósea del fémur proximal. Análisis de una muestra esqueletal

Resumen Objetivo Los analisis de osteoporosis en restos oseos cobran relevancia en tanto permiten evaluar el estado de salud osea de una poblacion. Una de las regiones oseas utilizadas para la estimacion de la perdida de la densidad mineral osea es la epifisis proximal del femur. El objetivo del trabajo fue analizar, a partir de restos esqueletarios, la variacion de la estructura osea del femur proximal en adultos y estudiar su relacion con la masa corporal, sexo y edad. Materiales y metodos Se tomo una muestra de 30 femures izquierdos pertenecientes a la coleccion osteologica «Prof. Dr. Romulo Lambre» de la Facultad de Ciencias Medicas (Universidad Nacional de La Plata), y se estimaron 2 indices radiologicos, el indice cortico metafisario y el indice trabecular. Posteriormente, se estudio la relacion entre los valores obtenidos y la masa corporal, el sexo y la edad de los individuos. Resultados El valor promedio estimado por el indice cortico metafisario senalo una baja calidad osea, sin diferencias entre sexos, y no presento correlaciones con la edad ni con el peso de los individuos. El 50% de los femures presento un valor de indice trabecular indicativo de osteoporosis, sin una diferencia significativa entre sexos. Conclusion La baja calidad osea del material se ajusto a lo esperado, debido a la edad de los sujetos analizados. Esto puede haber interferido en la visibilidad de otros procesos, ocurridos en vida, que podrian haber sido causantes de la perdida de densidad mineral osea.

Circadian rhythm of VEGF expression in the liver of hepatectomized-tumor-bearing adult and young mice

Abstract We analyzed VEGF expression in regenerating liver (after partial hepatectomy) of tumor-bearing adult and young mice, throughout one complete circadian cycle. The animals were sacrificed every 4 h, from 26 to 46 h post-hepatectomy. Liver samples were processed for immunohistochemistry. The results showed circadian variation of VEGF expression in hepatectomized mice (control group) and hepatectomized-tumor-bearing mice. The maximum value of VEGF expression was found at 16:00/30 h of day/hour post-hepatectomy (HD/HPH) in tumor-bearing young mice, and at 20:00/34 HD/HPH in the controls. In adult mice the maximum values of VEGF expression were at 16:00/30 HD/HPH in tumor-bearing mice, and at 08:00/46 HD/HPH in the controls. Young tumor-bearing mice showed significantly higher mean values than the controls. In conclusion, the presence of the tumor in the animals induces modifications in the intensity and the temporal distribution of the circadian curves of VEGF expression.

HIPEROSTOSIS ESQUELÉTICA DIFUSA IDIOPÁTICA EN UNA COLECCIÓN OSTEOLÓGICA CONTEMPORÁNEA (LA PLATA, BUENOS AIRES, ARGENTINA) / Difusse Idiopathic Skeletal Hyperostosis in a contemporary osteological collection (La Plata, Buenos Aires, Argentina)

La Hiperostosis Esqueletica Difusa Idiopatica (DISH) es una enfermedad caracterizada por provocar anquilosis entre cuerpos vertebrales, sumada a la osificacion masiva de ligamentos y tendones en el resto del sistema esqueletal. El objetivo del presente trabajo es establecer la prevalencia de DISH en una coleccion osteologica documentada contemporanea y discutir rasgos patognomonicos y factores de riesgo asociados. A fin de establecer un diagnostico se relevo, en 100 individuos adultos, la formacion de bloques oseos de al menos tres vertebras fusionadas por la osificacion de ligamento vertebral anterior. Se considero ademas que no estuvieran comprometidos los espacios intervertebrales y la articulacion sacroiliaca. En la zona extra espinal se registraron como evidencia complementaria la presencia de entesopatias. Como resultado del analisis se observaron seis individuos con DISH, sin diferencias significativas entre ambos sexos. El segmento vertebral principalmente afectado fue el toracico, los espacios intervertebrales no se vieron comprometidos en ningun caso y la articulacion sacroiliaca tampoco presento senales de osificacion patologica; a la vez que se relevaron numerosas entesopatias. Las prevalencias observadas se deberian a la avanzada edad de los individuos analizados y las caracteristicas nutricionales de la poblacion de referencia. Abstract The diffuse idiopathic skeletal hyperostosis (DISH) is a disease characterized by vertebral ankylosis , with massive ligaments and tendons ossification in the rest of the skeletal system. The aim of this study is to establish the prevalence of DISH in a well-documented and contemporary osteological collection, and to discuss pathognomonic features and associated risk factors. In order to establish the diagnosis, we registered, in 100 adults, the formation of bone blocks, with at least three fused vertebrae by ossification of the anterior vertebral ligament. It was also considered that were not compromise of the intervertebral spaces and sacroiliac joint. The extra-spinal area was analyzed as additional evidence because of enthesopathies .The results showed six individuals with DISH, with no significant differences between the sexes. The thoracic segment was the most affected, intervertebral spaces were not compromised in any way and the sacroiliac joint did not provide signs of ossification, while numerous enthesopathies were detected. The prevalences observed are due to the advanced age of the individuals analyzed and the nutritional characteristics of the reference population.

Circadian rhythms of proliferation events in two mouse carcinomas

We studied the index of DNA synthesis (DNAs) of two cellular carcinomas: the hepatocellular ES12a and the mammary TN60 of mice, throughout one circadian cycle. In the results, we observed that both tumors have circadian rhythms (CRs), but the peaks of DNAs vary. Besides, the mean of DNAs along 24 h shows significative differences, the TN60 has higher values than the ES12a. These observed CR in the DNAs index in both carcinomas mean that, at least in partly, the proliferation of cancer cells can be regulated by endocrine factor as it normally occurs in ordinary cells. The big problem we can find for the chronopharmacology is that it is impossible to know in advance the rate of proliferation of each tumor.