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Biomedical subjects

R Robles

Publications and source records attributed to R Robles.

At least 109 records · Page 6Linked to original sources
PubMed1999

Localization, regulation and possible consequences of apoptotic protease-activating factor-1 (Apaf-1) expression in granulosa cells of the mouse ovary.

The recent characterization of apoptotic protease-activating factor-1 (Apaf-1) in vertebrates as a putative homolog of the Caenorhabditis elegans gene, ced-4, indicates that the third major arm of the C. elegans programmed cell death machinery has also been conserved through evolution. Although apoptosis is now known to be important for ovarian follicular atresia in vertebrates, nothing is known of the role of Apaf-1 in ovarian function. Herein we show by immunohistochemical analysis that Apaf-1 is abundant in granulosa cells of early antral follicles whereas in vivo gonadotropin priming completely suppresses Apaf-1 expression and granulosa cell apoptosis. Western blot analysis of fractionated protein extracts prepared from granulosa cells before and after in vitro culture without hormonal support to induce apoptosis indicated that mitochondrial cytochrome c release, a biochemical step required for the activation of Apaf-1, occurs in granulosa cells cultured in vitro. Moreover, Western blot analysis of procaspase-3 processing, a principal downstream event set in motion by activated Apaf-1, indicated that healthy granulosa cells possess almost exclusively the inactive (pro-) form of the enzyme whereas granulosa cells deprived of hormonal support rapidly process procaspase-3 to the active enzyme. Lastly, we show that serum-starved granulosa cells activate caspase-3-like enzymes both prior to and after nuclear pyknosis, as revealed by a single-cell fluorescent caspase activity assay. These data, combined with previous observations regarding the role of homologs of the two other C. elegans cell death regulatory genes, ced-9 (Bcl-2 family members) and ced-3 (caspases), in atresia fully support the hypothesis that granulosa cell apoptosis is precisely coordinated by all three major arms of a cell death program conserved through evolution.

Animals↗
PubMed1999

Recovery and half-life of von Willebrand factor-cleaving protease after plasma therapy in patients with thrombotic thrombocytopenic purpura.

Plasma exchange using fresh-frozen plasma (FFP) for replacement was given to two brothers during a relapse of thrombotic thrombocytopenic purpura (TTP). A constitutional deficiency of von Willebrand factor(vWF)-cleaving protease had been previously established in both patients. No inhibitor of vWF-cleaving protease was present in patients' plasmas. They received plasma exchange for four and three consecutive days, respectively. In both patients, the activity of vWF-cleaving protease after the first plasmapheresis session was evaluated and was found to be virtually identical to anticipated activity calculated from predicted patient plasma volume and volume of exchanged plasma. Pathologic platelet counts and lactate dehydrogenase levels were normalized in both patients within 4-6 days. The biologic half-life of vWF-cleaving protease was determined in these patients following the last plasma exchange. The respective half-lives of 3.3 and 2.1 days represent the lowest known clearance rates of proteases in circulating human plasma. Another patient with relapsing TTP was treated with plasma exchange and/or plasma infusion for 10 consecutive days during the first relapse, 221-231 days after the initial TTP event. Pharmacokinetic studies of vWF-cleaving protease were performed after plasma exchange on day 221 and after plasma infusion on day 231. High level of an IgG in patient plasma, capable of completely inhibiting protease activity in an equal volume of normal plasma, had been established prior to first plasmapheresis. There was no measurable protease activity at any time during plasma therapy. Following plasma exchange, the level of the inhibitor was transiently slightly depressed. After 10 days of plasma therapy, the concentration of the inhibitor in patient plasma was increased about 5-fold. We suggest that, in contrast to protease deficient patients without circulating inhibitor, complementary therapy including immunosuppressive treatment, vincristine and/or splenectomy is indicated in patients with acquired inhibitors of vWF-cleaving protease. Testing for vWF-cleaving protease inhibitor may be useful in predicting the response to plasma exchange in patients with TTP.

ADAM Proteins↗
PubMed1998

von Willebrand factor-cleaving protease in thrombotic thrombocytopenic purpura and the hemolytic-uremic syndrome.

BACKGROUND: Thrombotic thrombocytopenic purpura and the hemolytic-uremic syndrome are severe microvascular disorders of platelet clumping with similar signs and symptoms. Unusually large multimers of von Willebrand factor, capable of agglutinating circulating platelets under high shear stress, occur in the two conditions. We investigated the prevalence of von Willebrand factor-cleaving protease deficiency in patients with familial and nonfamilial forms of these disorders. METHODS: Plasma samples were obtained from 53 patients with thrombotic thrombocytopenic purpura or hemolytic-uremic syndrome. Von Willebrand factor-cleaving protease was assayed in diluted plasma samples with purified normal von Willebrand factor as the substrate. The extent of the degradation of von Willebrand factor was assessed by electrophoresis in sodium dodecyl sulfate-agarose gels and immunoblotting. To determine whether an inhibitor of von Willebrand factor-cleaving protease was present, we measured the protease activity in normal plasma after incubation with plasma from the patients. RESULTS: We examined 30 patients with thrombotic thrombocytopenic purpura and 23 patients with the hemolytic-uremic syndrome. Of 24 patients with nonfamilial thrombotic thrombocytopenic purpura, 20 had severe and 4 had moderate protease deficiency during an acute event. An inhibitor found in 20 of these patients was shown to be IgG in five of five tested plasma samples. Of 13 patients with nonfamilial hemolytic-uremic syndrome, 11 had normal levels of activity of von Willebrand factor-cleaving protease during the acute episode, whereas in 2 patients, the activity was slightly decreased. All 6 patients with familial thrombotic thrombocytopenic purpura lacked von Willebrand factor-cleaving protease activity but had no inhibitor, whereas all 10 patients with familial hemolytic-uremic syndrome had normal protease activity. In vitro proteolytic degradation of von Willebrand factor by the protease was studied in 5 patients with familial and 7 patients with nonfamilial hemolytic-uremic syndrome and was normal in all 12 patients. CONCLUSIONS: Nonfamilial thrombotic thrombocytopenic purpura is due to an inhibitor of von Willebrand factor-cleaving protease, whereas the familial form seems to be caused by a constitutional deficiency of the protease. Patients with the hemolyticuremic syndrome do not have a deficiency of von Willebrand factor-cleaving protease or a defect in von Willebrand factor that leads to its resistance to protease.

ADAM Proteins↗
PubMed1998

Acquired deficiency of von Willebrand factor-cleaving protease in a patient with thrombotic thrombocytopenic purpura.

Plasma of patients with thrombotic thrombocytopenic purpura (TTP) has been shown to contain unusually large von Willebrand factor (vWF) multimers that may cause platelet agglutination in vivo. Fresh frozen plasma infusions and plasma exchange represent the most efficient therapy of acute TTP. A specific protease responsible for cleavage of vWF multimers has been recently isolated from normal human plasma and was found to be deficient in four patients with chronic relapsing TTP. We examined the activity of the vWF-cleaving protease in plasma samples collected over a period of 400 days from a further patient with recurrent episodes of TTP who was treated by plasma exchange, plasma infusion, vincristine, corticosteroid therapy, and splenectomy. Complete deficiency of the vWF-cleaving protease was established during the first episode of TTP. The ensuing normalization of the platelet count was associated with the appearance of the protease activity. Three months after remission from the initial TTP event, the vWF-cleaving protease again disappeared and the platelet count gradually decreased. Relapses of severe thrombocytopenia occurred 7 and 11 months after the first acute episode of TTP. Deficient protease activity was associated with the presence in the patient plasma of an inhibitor that was found to be an IgG. Plasma exchange/infusion was followed by a temporary increase in the antibody titer, whereas treatment with vincristine led to a recovery of the platelet count without affecting the inhibitor concentration. Splenectomy and corticosteroid treatment resulted in disappearance of the autoantibody and normalization of the protease activity and of the platelet count. Our data suggest that the thrombocytopenia in this patient with TTP was associated with a lack of the vWF-cleaving protease activity depleted by an autoimmune mechanism. This case, together with our previously reported patients, leads us to conclude that acquired as well as constitutional deficiency of the vWF-cleaving protease may predispose to TTP.

ADAM Proteins↗
PubMed1998

Laparoscopic cholecystectomy vs open cholecystectomy in the treatment of acute cholecystitis: a prospective study.

OBJECTIVE: To compare the results of laparoscopic cholecystectomy (LC) with those of open cholecystectomy (OC) in the treatment of acute cholecystitis. DESIGN: A prospective, nonrandomized trial. SETTING: "Virgen de la Arrixaca" University Hospital, El Palmar (Murcia), Spain. PATIENTS: One hundred fourteen patients underwent LC, and 110 underwent OC. The patients underwent surgery within 72 hours of the onset of symptoms. The patients were selected for LC or OC depending on the surgeon's experience in laparoscopic surgery. MAIN OUTCOME MEASURES: Operating time, rate of conversion from LC to OC, complications, and length of hospital stay. RESULTS: Conversion from LC to OC was necessary in 15% of the patients. The mean operating time was 77 minutes for the OC group and 88 minutes for the LC group (P<.001). Complications occurred in 14% of the patients in the LC group and in 23% of the patients in the OC group, with no significant differences between the 2 groups (P=.06). The number of moderate or severe complications was similar in both groups, whereas mild complications were more common in the OC group (P<.02). The length of the hospital stay averaged 8.1 days for the OC group and 3.3 days for the LC group (P<.001). CONCLUSIONS: Laparoscopic cholecystectomy is a safe, valid alternative to OC in patients with acute cholecystitis. The technique has a low rate of complications, implies a shorter hospital stay, and offers the patient a more comfortable postoperative period than OC.

Acute Disease↗
PubMed1998

Lipid peroxidation and antioxidants in erythrocyte membranes of full-term and preterm newborns.

The most probable factor connecting premature infant problems such as retinopathy, intraventricular hemorrhage and chronic lung disease appears to be the excessive production of oxygen free radicals which can occur as a consequence of oxygen therapy. The aim of our investigation was to elucidate the possible correlations between lipid peroxidation, in this study measured as hydroperoxides production, and antioxidant concentrations in erythrocyte membranes of both full term and preterm infants. Hydroperoxide concentrations were found to be high, especially in premature infants, in erythrocyte membranes at birth and in the initial days of life. The erythrocyte membranes were also found to contain low levels and/or low activities of antioxidant defense mechanisms which was more evident in premature newborns where alpha-tochopherol levels were significantly lower in comparison to full term infant levels. Furthermore, when premature infants undergo oxygen therapy these effects were exacerbated. These results demonstrate that at birth, particularly in the premature newborn, the degree of oxidative stress outweighs the antioxidant defense mechanisms.

Antioxidants↗
PubMed1998

Subtotal colectomy vs. intraoperative colonic irrigation in the management of obstructed left colon carcinoma.

PURPOSE: Whether primary anastomosis should be performed after segmental resection with intraoperative colonic irrigation or subtotal colectomy is not yet established in the surgical treatment of obstructive left colon carcinoma. In this prospective, nonrandomized study, we present the results of 66 patients undergoing one-stage surgery for obstructed left colon carcinoma. PATIENTS AND METHODS: We compared two techniques, subtotal colectomy (35 patients) and intraoperative colonic irrigation with segmental resection and immediate anastomosis (31 patients). RESULTS: The mortality rate was similar in both groups, 8.5 percent in the subtotal colectomy group and 3.2 percent in the intraoperative colonic irrigation group. The surgical complication rate was significantly higher in the intraoperative colonic irrigation group (41.9 percent) than in the subtotal colectomy group (14.2 percent; P < 0.05). Mean operating time was significantly lower in the subtotal colectomy group than in the intraoperative colonic irrigation group (P < 0.05). Both groups had a similar mean duration of hospital stay. Ten patients who underwent subtotal colectomy (31.2 percent) presented with diarrhea in the immediate postoperative period, which disappeared spontaneously or with antidiarrheal medication; a disabling diarrhea persisted in two patients only (6.2 percent). CONCLUSION: We believe that subtotal colectomy is the treatment of choice for obstructed left-sided colonic carcinoma. Segmental resection with intraoperative colonic irrigation is more appropriate than subtotal colectomy only in patients with carcinomas of the rectosigmoid junction or with previous anal incontinence to avoid the appearance of postoperative diarrhea.

Adult↗
PubMed1998

Use of bile cytology for early diagnosis of complications in orthotopic liver transplantation.

We conducted a daily analysis of bile cellularity in 25 patients undergoing 29 orthotopic liver transplants (OLT) and correlated the cytological parameters with the clinical outcome of each patient. The 16 patients without complications only showed slides with cells during the first 4-5 postoperative days. The four patients with primary non-function (PNF) of the graft had a high cell density up to the time of the retransplant, with a preponderance of polymorphonuclear (PMN) leucocytes (59.2%) and epithelial cells (29.2%). During the episodes of sepsis (n = 3) and rejection (n = 7) we noted the sudden appearance of high cellularity, almost exclusively PMN leucocytes (96.5%), and a preponderance of PMN leucocytes (84.2%) with appreciable percentages of mononuclear cells and macrophages as well as the early appearance of lymphoblasts in the rejection episodes. Our results show that bile cytology can be a useful method for diagnosing graft complications in liver transplantation.

Adult↗
PubMed1998

Help seeking for mental health care among poor Puerto Ricans: problem recognition, service use, and type of provider.

OBJECTIVES: This study examines the effects of health, predisposing, and enabling factors on recognition of a mental health problem, use of formal mental health care, and contact with a specialized mental health provider. METHODS: Interviews were conducted with a probability sample of 3,435 adults. The variables examined include measures of mental health; social and demographic factors; and enabling factors relevant to the help-seeking process. RESULTS: Subjective and objective measures of mental health were associated with the recognition of a mental health problem. The objective assessment of definite need for services was relevant for the use of formal services. However, the subjects' perception of poor mental health was strongly related to receiving care from a mental health specialist. Although interaction with social networks is associated with use of formal services, low economic strain is related to receiving care from the specialty sector. CONCLUSIONS: The results support the importance of using multiple measures of mental health problems. The finding that individuals' perceived economic strain increases the likelihood of receiving specialized care suggests that studies of economic barriers to the use of mental health services might benefit from the adoption of measures that assess perceived economic circumstances.

Adolescent↗
PubMed1998

Treatment of primary and secondary spontaneous pneumothorax using videothoracoscopy.

Our aim is to assess the results of surgical treatment for spontaneous pneumothorax (SP) using video-assisted thoracoscopic surgery (VATS) and to determine whether this technique is equally effective for primary SP (PSP) and secondary SP (SSP). A prospective study was performed on 54 patients with persistent and recurrent SP (42 PSPs and 12 SSPs). Mean operating time, time before drainage removal, and hospital stay were significantly longer with SSP (67.1 vs. 48.1 minutes; 5.4 vs. 3.6 days; and 7.7 vs. 5.3 days; p < 0.01, respectively). There was one conversion due to bleeding (PSP). Postoperative complications were greater with SSP (33% vs. 12%; p = 0.09). Although these were mild in all cases, the most common was air leak (25 vs. 5%; p = 0.06). The SP persisted in three cases [2 (5%) with PSP, and 1 (8%) with SSP] and recurred in 2 (1 in each group; 2% and 8%, respectively). Follow-up averaged 24 months. VATS is effective in the surgical treatment of PSP and SSP, although the technical difficulty, morbidity rate, hospital stay, and incidence of persistences and recurrences are greater in the latter than in the former.

Adult↗
PubMed1998

Laparoscopic vs. open cholecystectomy in patients aged 65 and older.

Laparoscopic cholecystectomy (LC) has displaced open cholecystectomy (OC) in the management of cholelithiasis. However, there are few studies on the role of this technique in patients who run a high risk of surgical complications. We performed a prospective study in 264 patients aged >65 years undergoing surgery for symptomatic cholelithiasis. They were divided into two groups according to the surgical technique performed: OC (131 patients) and LC (133 patients). Conversion from LC to OC was necessary in 11 patients (8.3%). Mean surgery time was 70.9 min for the OC group and 75 min for the LC group. The LC group had a lower rate of postoperative complications (13.53%) than the OC group (23.6%). The incidence of mild complications was similar in both groups; however, the rate of moderate complications was significantly higher in the OC group. Hospital stay was significantly longer in the OC group (9.9 days) than in the LC group (3.71 days). These results suggest that LC should be indicated in elderly patients, as they are better than those obtained with with OC and involve a lower morbidity rate and shorter hospital stay.

Age Factors↗
PubMed1997

Long-term results of liver transplantation in familial amyloidotic polyneuropathy type I.

BACKGROUND: The aim of this article is to report our experience regarding the survival and the evolution of polyneuropathy of the extremities and autonomic dysfunction in 18 liver transplant patients with familial amyloidotic polyneuropathy type I after a mean follow-up of more than 2.5 years for 13 patients. METHODS: The actuarial survival rate of the 18 patients is 72.2% and 60.1%, respectively, at 12 and 58 months. RESULTS: In all the patients we noted clinical improvement of the polyneuropathy of the extremities and autonomic dysfunction during the first 6 months after transplant. The clinical data due to autonomic nervous system involvement showed an earlier improvement than those due to nervous motor involvement. CONCLUSIONS: In conclusion, our results suggest that liver transplant may be useful in the treatment of certain cases of familial amyloidotic polyneuropathy to stop the neurological deterioration of the patients and to avoid the fatal end of the disease.

Adult↗
PubMed1997

Deficient activity of von Willebrand factor-cleaving protease in chronic relapsing thrombotic thrombocytopenic purpura.

In patients with thrombotic thrombocytopenic purpura (TTP), excessive intravascular platelet aggregation has been associated with appearance in plasma of unusually large von Willebrand factor (vWF) multimers. These extremely adhesive vWF multimers may arise due to deficiency of a "depolymerase" cleaving vWF to smaller molecular forms, either by reducing the interdimeric disulfide bridges or by proteolytic degradation. We studied the activity of a recently described vWF-cleaving protease in four patients with chronic relapsing TTP. Diluted plasma samples of TTP patients were incubated with purified normal human vWF in the presence of a serine protease inhibitor, at low ionic strength, and in the presence of urea and barium ions. The extent of vWF degradation was assayed by electrophoresis in sodium dodecyl sulfate-agarose gels and immunoblotting. Four patients, that included two brothers, with chronic relapsing TTP displayed either substantially reduced levels or a complete absence of vWF-cleaving protease activity. In none of these patient plasmas was an inhibitor of or an antibody against the vWF-cleaving protease established. Our data suggest that the unusually large vWF multimers found in TTP patients may be caused by deficient vWF-cleaving protease activity. Deficiency of this protease may be inherited in an autosomal recessive manner and seems to predispose to chronic relapsing TTP. The assay of the vWF-cleaving protease activity may be used as a sensitive diagnostic tool for identification of subjects with a latent TTP tendency.

ADAM Proteins↗
PubMed1997

Thoracoscopic partial pericardiectomy in the diagnosis and management of pericardial effusion.

BACKGROUND: An effort was made to present our experience with thoracoscopy in the diagnosis and management of pericardial effusions. METHODS: Twenty-two partial pericardiectomies were performed with the thoracoscopic approach in patients with pericardial effusions, the etiology of which was uremic (n = 7), neoplastic (n = 8), idiopathic (n = 5), septicemia (n = 1), and postpericardiotomy (n = 1). All cases had grade III-IV/IV radiological cardiomegaly and ultrasonographic confirmation of the effusion. We found hemodynamic compromise in 17 patients. The operation, requiring the insertion of three trocars, enabled us to remove a large part (approximately 6 x 10 cm) of the left anterolateral side of the pericardium and aspirate the effusion contents for diagnostic and therapeutic purposes. RESULTS: In five cases we found coexisting pleural effusions. The pericardial effusion had a mean volume of 817 ml, which was serous in 11 cases, hematic in six, serohematic in four, and purulent in one. Cytology of the pericardial effusion was positive for neoplasia in four cases (one pulmonary neoplasia, two breast carcinomas, and one lymphoma). We observed conversion to grade I/IV cardiomegaly in 16 cases and a return to normality in the other six, with the absence of ultrasonographic effusion in all cases. There was no recurrence during the mean follow-up period of 20.5 months (range: 2-47). CONCLUSIONS: The thoracoscopic management of pericardial effusions is a simple and effective technique that allows us to create a large pericardial window that drains the effusion definitively, determines its etiology, and explores and treats coexisting pleural lesions, all without recurrences.

Adolescent↗
PubMed1997

Lipid peroxidation and antioxidants in newborns.

The aim of this investigation was to elucidate a possible correlation between lipid peroxidation, antioxidant concentrations and erythrocyte membrane fluidity in plasma from newborns. Ten healthy newborns were recruited. Venous blood samples were collected at birth, and thereafter at 3 and 72 h postnatal age. The following parameters were assessed: hydroperoxides, Coenzyme Q10 and alpha-tocopherol both in plasma and in erythrocyte membranes, and fluorescence polarization (as a tool for assessing membrane fluidity). Hydroperoxides were shown to be high in erythrocyte membranes at birth and significantly decreased at 3 and 72 h after birth. In the erythrocyte membranes, coenzyme Q10 content showed an opposite behaviour with respect to the plasma compartment. Membrane fluidity appeared unchanged even in the presence of the above mentioned modifications.

Antioxidants↗
PubMed1997

Quantification of duodenogastric reflux in Barrett's esophagus.

OBJECTIVES: Our objective was to assess the role of reflux of duodenal contents in the genesis of Barrett's esophagus. Therefore, we performed a study to quantify duodenogastric reflux, using 99mTc-HIDA quantification in gastric juice after continuous intravenous infusion of the same. METHODS: The study contained 20 patients with Barrett's esophagus (10 uncomplicated and 10 complicated by ulcers and/or stenosis), 10 patients with peptic esophagitis without Barrett's esophagus (two grade I, four grade II, and four grade III, according to Savary-Miller), and 10 healthy volunteers who made up the control group. Comparisons were made between the groups. RESULTS: When we considered the groups overall, we observed that the 20 patients with Barrett's esophagus had higher reflux rates (p < 0.01) than either the 10 patients with peptic esophagitis without Barrett's esophagus, or the 10 controls. Complicated Barrett's esophagus presented higher reflux rates than uncomplicated Barrett's esophagus, although the differences were not statistically significant. However, on analyzing the results after considering the groups case by case, we see that the mean reflux rate in the Barrett's esophagus groups is due to five patients presenting much higher rates than the rest. CONCLUSIONS: Our results suggest that duodenogastric reflux might be involved in the appearance of Barrett's esophagus and its related complications, although only in certain cases. The pathogenesis of Barrett's esophagus is probably multifactorial, and other factors must be involved.

Adult↗
PubMed1997

[Familial visceral myopathy].

We report a patient with intestinal pseudo-obstruction in which both the histopathological findings and the clinical history strongly suggest a visceral myopathy of familial type. Reviewing the clinicopathological descriptions of the different families appearing in the literature, is evident that both the presentation (severity, distribution of lesions, etc) and the inheritance pattern seem not to be clearly delimitated, and it has been recently suggested that it may be related to the mitochondrial myopathies. The useless of conventional biopsy procedures (due to the almost exclusive affectation of the external muscle layer of the intestinal wall); the frequently patchy distribution of the lesions (which might be overlooked in a routine histological handling of a resection specimen) and the extensive range of symptoms of the disease, support the paramount importance of a high index of suspicion (obviously, the clinical history plays a fundamental role). In this setting, it is also interesting to emphasize the utility of manometric studies for the correct diagnosis and management of these patients; as well their possible application to identify asymptomatic heterozygotes.

Adolescent↗