Biomedical subjects

Juan Roa

Publications and source records attributed to Juan Roa.

10 recordsLinked to original sources

PubMed2007

Sexual differentiation of Kiss1 gene expression in the brain of the rat.

The Kiss1 gene codes for kisspeptins, which have been implicated in the neuroendocrine regulation of reproduction. In the brain, Kiss1 mRNA-expressing neurons are located in the arcuate (ARC) and anteroventral periventricular (AVPV) nuclei. Kiss1 neurons in the AVPV appear to play a role in generating the preovulatory GnRH/LH surge, which occurs only in females and is organized perinatally by gonadal steroids. Because Kiss1 is involved in the sexually dimorphic GnRH/LH surge, we hypothesized that Kiss1 expression is sexually differentiated, with females having more Kiss1 neurons than either males or neonatally androgenized females. To test this, male and female rats were neonatally treated with androgen or vehicle; then, as adults, they were left intact or gonadectomized and implanted with capsules containing sex steroids or nothing. Kiss1 mRNA levels in the AVPV and ARC were determined by in situ hybridization. Normal females expressed significantly more Kiss1 mRNA in the AVPV than normal males, even under identical adult hormonal conditions. This Kiss1 sex difference was organized perinatally, as demonstrated by the observation that neonatally androgenized females displayed a male-like pattern of adulthood Kiss1 expression in the AVPV. In contrast, there was neither a sex difference nor an influence of neonatal treatment on Kiss1 expression in the ARC. Using double-labeling techniques, we determined that the sexually differentiated Kiss1 neurons in the AVPV are distinct from the sexually differentiated population of tyrosine hydroxylase (dopaminergic) neurons in this region. Our findings suggest that sex differences in kisspeptin signaling from the AVPV subserve the cellular mechanisms controlling the sexually differentiated GnRH/LH surge.

Animals↗

PubMed2006

[Immunohistochemical expression of the E-cadherin-catenin complex in gastric cancer].

BACKGROUND: The E-cadherin/catenin complex plays an essential role in the control of epithelial differentiation. Abnormal expression in tumors correlates with histological grade, advanced stage and poor prognosis. AIM: To evaluate the expression pattern of E-cadherin/catenin complex in gastric carcinoma and analyze their association with tumor clinicopathological features and patient survival. MATERIAL AND METHODS: Inmunohistochemical staining of E-cadherin, alpha and ss-catenin was performed from paraffin specimens of 65 gastric carcinomas. RESULTS: Abnormal expression of E-cadherin, alpha and ss-catenin was demonstrated in 82%, 85% and 88% of gastric carcinomas, respectively. There was a significant correlation between abnormal expression and Lauren pathological classification and depth of infiltration, but not with tumor stage, positive lymph node metastases and survival. CONCLUSION: Abnormal expression of E-cadherin, alpha and ss-catenin occurs frequently in gastric carcinoma and correlates with histological grade.

Cadherins↗

PubMed2006

Preneoplastic lesions in gallbladder cancer.

BACKGROUND: Gallbladder cancer is an uncommon disease except in countries like Chile and areas of India and Japan. The knowledge regarding the etiology and mechanisms through which this neoplasia is developed is significantly less compared to other malignant tumors. RESULTS: The epithelial lesions involved in gallbladder carcinogenesis are dysplasia and adenomas that represent two biologically distinct carcinogenetic models. Dysplasia progresses to carcinoma in situ (CIS) and subsequently becomes invasive. Over 80% of invasive gallbladder cancers present areas adjacent to the CIS and epithelial dysplasia. Other authors have demonstrated adenomatous areas in carcinomas, or malignant transformation in an adenoma. The low incidence of gallbladder adenomas (0.14% of cholecystectomies) and the presence of adenomatous remnants in the neighboring mucosa to early carcinomas in less than 3% of the cases suggest the limited importance of this carcinogenic pathway. Epithelial dysplasia which is not associated with gallbladder cancer is observed in approximately 1% of cholecystectomies for symptomatic lithiasis. Metaplasia, dysplasia, and CIS are present in the mucosa adjacent to the cancer in 66%, 81.3%, and 69%, respectively. The average ages of patients with dysplasia not associated to cancer (51.9 years), early carcinomas (56.8 years), and advanced carcinomas (62.9 years) demonstrate a gradient which suggests the progression of these lesions. CONCLUSIONS: From the morphological point of view, the dysplasia-carcinoma sequence is the most plausible carcinogenic pathway for gallbladder cancer, a process which would require a period of approximately 10 years.

Adenocarcinoma↗

PubMed2006

Gallstones and gallbladder cancer-volume and weight of gallstones are associated with gallbladder cancer: a case-control study.

BACKGROUND: Gallstones are considered the most important risk factor for gallbladder cancer. AIM: To identify differences in the number, weight, volume, and density of gallstones associated with chronic cholecystitis (CC), gallbladder dysplasia (GD), and gallbladder cancer (GBC). METHODS: A total of 125 cases were selected, of which 93 had gallstones associated with GBC and 31 had gallstones associated with GD. The controls were those with CC, matched by sex and age. The number, weight, volume, and density of these gallstones were examined in order to determine differences and relative cancer risk. RESULTS: Number: Multiple gallstones were present in over 76% of cases (GBC and GD) and controls (P = ns). The average number of multiple stones was 21 in GBC versus 14 in controls (P < 0.01). Weight: The average weight of the gallstones was 9.6 g in GBC versus 6.0 g in controls (P = 0.0004). The average weight in multiple stones over 10 g had strong association with GBC (P = 0.0006). Volume: The average volume was 11.7 and 6.48 ml in GBC and controls (P = 0.0002). Average volumes of 6, 8, and 10 ml had a relative cancer risk of 5, 7, and 11 times, respectively. Size: No differences were shown between GBC, GD, and controls. CONCLUSIONS: The volume of gallstones associated with other risk factors of GBC may be helpful in prioritizing cholecystectomies in symptomatic patients.

Analysis of Variance↗

PubMed2006

Expression of hypothalamic KiSS-1 system and rescue of defective gonadotropic responses by kisspeptin in streptozotocin-induced diabetic male rats.

Hypogonadotropism is a common feature of uncontrolled diabetes, for which the ultimate mechanism remains to be elucidated. Kisspeptins, ligands of G protein-coupled receptor 54 (GPR54) encoded by the KiSS-1 gene, have recently emerged as major gatekeepers of the gonadotropic axis. Alteration in the hypothalamic KiSS-1 system has been reported in adverse metabolic conditions linked to suppressed gonadotropins, such as undernutrition. However, its potential contribution to defective gonadotropin secretion in diabetes has not been evaluated. We report herein analyses of luteinizing hormone (LH) responses to kisspeptin and hypothalamic expression of the KiSS-1 gene in streptozotocin (STZ)-induced diabetic male rats. In addition, functional studies involving kisspeptin replacement or continuous administration of leptin and insulin to diabetic male rats are presented. Kisspeptin administration evoked robust LH and testosterone bursts and enhanced postgonadectomy LH concentrations, despite prevailing attenuation of gonadotropic axis in diabetic animals. In addition, hypothalamic KiSS-1 mRNA levels were unambiguously decreased in diabetic male rats, and the postorchidectomy rise in KiSS-1 mRNA was severely blunted. Repeated administration of kisspeptin to diabetic rats evoked persistent LH and testosterone responses and partially rescued prostate and testis weights. In addition, central infusion of leptin, but not insulin, was sufficient to normalize hypothalamic KiSS-1 mRNA levels, as well as LH and testosterone concentrations. In summary, we provide evidence for altered expression of the hypothalamic KiSS-1 system in a model of uncontrolled diabetes. This observation, together with the ability of exogenous kisspeptin to rescue defective LH responses in diabetic rats, unravel the physiopathological implication, and potential therapeutic intervention, of the KiSS-1 system in altered gonadotropin secretion of type 1 diabetes.

Animals↗

PubMed2004

[Clinicopathological features of gallbladder polyps and adenomas].

BACKGROUND: Chile has a high frequency of gallbladder cancer. Polyps are common lesions of gallbladder mucosa but there is little information about their morphological features. AIM: To report the clinical and pathological features of 219 gallbladder polyps. MATERIAL AND METHODS: Cholecystectomites samples in which a polypoid lesion was diagnosed microscopically. In all cases, complete clinical information and digitalized images of the complete surgical specimens was reviewed. RESULTS: In a period of 10 years, 21,412 gall-bladders were processed. Among these, 884 carcinomas were diagnosed and in 219 cases (1%) a polyp was found. One hundred and eighty three patients were females (mean age 49.3 years) and 36 males (mean age 53.4 years). The preoperative diagnosis of gallbladder polyp wars done only in 26 cases (12%). Eighty five percent of polyps were non-neoplastic (metaplastic in 32%, cholesterol in 29%, hyperplastic in 22% and inflammatory in 2%). The remaining 15% were adenomas. Seventy five percent of non-neoplastic polyps were located in the proximal half of the gallbladder and 88% of adenomas in the distal half. Ninety five percent of non-neoplastic polyps measured less than 10 mm. Among adenomas, 47% measured less than 5 mm and 28% more than 10 mm. Smaller polyps were of cholesterol and larger polyps were adenomas. Eight adenomas were associated with an adenocarcinoma, two had less than 5 mm length. Mean age of patients with adenomas associated to cancer was higher than patients with pure adenomas (64.6 and 44.3 years respectively, p > 0.001). CONCLUSIONS: There are size and location differences between non neoplastic polyps and adenomas. Adenomas associated to cancer may measure less than 5 mm. Therefore the polyp size criteria to decide surgical behavior in symptomatic gallstone patients may be misleading.

Adenocarcinoma↗

PubMed2004

[DNA content and survival in subserous gallbladder carcinoma].

BACKGROUND: The clinical and morphological characterization of the subserous gallbladder carcinomas is controversial. AIM: To study the prognostic importance of DNA content of subserous gallbladder carcinoma. MATERIAL AND METHODS: We studied 104 females aged 60+/-12 years old and 16 men aged 70+/-13 years old. In all of them diagnosis was established after mapping of cholecystectomy sample and had a complete clinical follow up. DNA content was measured by flow cytometry. RESULTS: All tumors were adenocarcinoma, and only 16% were well differentiated. Aneuploidy was observed in 29 cases (26%) with DNA index fluctuating between 1.1 and 1.8. Lymphatic vessel tumor involvement was present in 16 of 22 cases with aneuploidy and in 22 of 46 diploid tumors (p=0.05). Eighty nine percent of aneuploid tumors were detected macroscopically and 11% were unapparent. Five years survival was non significantly better among patients with diploid tumors than in patients with aneuploid tumors (45 and 28%, respectively, p=0.2). The histological differentiation was the only variable significantly associated with survival. CONCLUSIONS: Aneuploidy is present in 26% of subserous gallbladder carcinoma. It is not related with any of the morphological or clinical variables studied in this series of patients.

Adenocarcinoma↗

PubMed2002

[Morphological prognostic elements in gallbladder cancer].

BACKGROUND: The exact survival rates and prognostic factors of gallbladder cancer are still incompletely known. AIM: To report the actuarial survival of patients with gallbladder cancer. MATERIAL AND METHODS: Six hundred thirty seven women, aged 59 years old as a mean and 108 men, aged 64 years old as a mean, with gallbladder cancer are reported. Patients were followed for up to 150 months. RESULTS: Two hundred twenty four patients had an early and 521 had an advanced carcinoma. Overall survival was 38% at ten years. Sex or ethnic origin did not influence survival. Early tumors had a 92% survival at 10 years whereas the survival of advanced tumors was 16% at 5 years. Subserous tumors had a 5 years survival of 32% whereas serous tumors had a 5 years survival of 11%. Well-differentiated advanced tumors had a significantly better survival than moderately or poorly differentiated tumors. Vascular or lymphatic infiltration was also associated to a lower survival. All patients with advanced tumors and vascular infiltration died before 5 years. CONCLUSIONS: Tumor infiltration and differentiation degree were the most important prognostic independent factors in gallbladder cancer.

Adenocarcinoma↗

PubMed2002

[Is gallbladder cancer a disease with bad prognosis?].

Gallbladder cancer is frequent in Chile, but it is not uniformly mortal. The diagnosis is usually made after a cholecystectomy, indicated for a symptomatic cholelithiasis. Global survival of gallbladder cancer can be as high as 40% at five years. In 69% of women of less than 30 years old, the tumor is detected in early stages. In these cases, cholecystectomy is the curative procedure, with a 90% survival at five years. According to our experience, cholecystectomies should be performed between 40 and 50 years of age in men and between 30 and 40 years in women. The prognostic factors that should be considered are symptoms associated to lithiasis, age, parity, obesity, size of stones and the size of the gallbladder. If the tumor is detected in early stages, the survival is good. The natural history of the disease would change significantly if all women with symptomatic stones were operated.

Adult↗

PubMed2002

[Subserous gallbladder carcinoma: expression of cadherine-catenine complex].

BACKGROUND: Subserous gallbladder carcinoma is difficult to diagnose and treat. There are no tissue markers with prognostic value in this type of tumor. AIM: To study the immunohistochemical expression of E-cadherin alpha and beta catenin in subserous gallbladder carcinoma. PATIENTS AND METHODS: One hundred seventeen subjects (103 women and 14 men aged 62 and 69 years as a mean, respectively), were studied. Thirty five gallbladder samples without evidence of cancer were used as controls. Expression of markers was studied with standard immunohistochemical techniques for formalin fixed and paraffin embedded tissue. RESULTS: Ninety seven percent of tumors were adenocarcinoma. A lower or absent expression of E-cadherin, alpha catenin and beta catenin was observed in 26, 33 and 29% of tumors, respectively. Actuarial five years survival was 37%. No association between macroscopic features of the tumor and survival was observed. Well differentiated tumors had a 73% survival, whereas less differentiated tumors had a 30% survival. Tumors with a normal expression of the markers had a slightly better survival, although not significant (p = 0.06). CONCLUSIONS: Approximately 30% of subserous gallbladder carcinoma have an abnormal expression of E-cadherin, alpha catenin and beta catenin. This abnormal expression has no relationship with prognosis and is probably secondary to the aberrant genic expression of the tumor.

Adult↗