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Biomedical subjects

F Castañeda

Publications and source records attributed to F Castañeda.

At least 19 recordsLinked to original sources
PubMed2005

Preparation of Entamoeba histolytica antigens without enzymatic inhibitors.

The goal of this work is to report a novel assay that preserves antigenicity of extracts with high protease content without using enzymatic inhibitors. A great reduction of proteolytic activity in the insoluble chloroform/methanol and heated amoebic fraction (IC:MC) was obtained by this method, even in the presence of sodium dodecyl sulphate and 2-mercaptoethanol. The substrates azo-casein and the hide powder azure were used to determine the reduction of proteolytic activity of IC:MC compared with the activity of crude extract and crude extract with iodoacetamide. The IC:MC SDS-PAGE pattern shows a higher quantity of bands than extract with the inhibitor iodoacetamide or than crude extract. In addition, anti-Entamoeba histolytica antibodies from amoebic liver abscess patients recognized a richer antigenic Western blot pattern in the IC:MC fraction than in crude extract alone or with inhibitor. The described method has proved to be suitable to preserve amoebic antigens for its use in diagnostic tests and it can be used for immunological response studies against E. histolytica antigens. Furthermore we propose that this method to obtain the IC:MC fraction can be applied for the study of other microorganisms or cells with high enzymatic content.

Animals↗
PubMed2001

Apoptosis induced in HepG2 cells by short exposure to millimolar concentrations of ethanol involves the Fas-receptor pathway.

PURPOSE: We previously found that ethanol-induced apoptosis is associated with an activation of caspase-3. However, the initial triggering of this process is yet unknown. Therefore, the present study was designed to determine whether the Fas-receptor pathway plays a role in the initiation by ethanol of human hepatocellular carcinoma (HepG2) cell apoptosis. METHODS: HepG2 cells were incubated with or without 1 mM ethanol for 24 h. Apoptosis was assessed by DNA fragmentation and caspase-8 activity. Selective inhibitors of caspase-8 and caspase-9 were used to analyze the role of both caspases on apoptosis. Soluble human Fas ligand (Fas-L) was determined by enzyme-linked immunosorbent assay (ELISA). A fluorescent dye was used to investigate the permeability of the mitochondrial outer membrane. A recombinant Fas fusion protein was used to inhibit the activation of Fas receptors. Human anti-Fas-L antibody was employed to neutralize Fas-L released from the cells. RESULTS: Caspase-8 activity increased significantly threefold (P < 0.005) after 12 h incubation of HepG2 cells with 1 mM ethanol whereas no change was observed in control cells. Incubation with caspase-8 inhibitor completely prevented apoptosis induced by ethanol (P < 0.001). In contrast, a caspase-9 inhibitor did not significantly reduce apoptosis. The permeability of the outer mitochondrial membrane was not altered. Neutralization of Fas-receptors by Fas fusion proteins completely attenuated ethanol-induced apoptosis in HepG2 cells treated with ethanol. CONCLUSIONS: These findings show that apoptosis induced by low concentrations of ethanol in human HepG2 cells is associated with Fas-receptor activation and subsequent caspase-8 activation. Triggering of apoptosis through Fas-receptors represents a mechanism of action different from that observed with high concentrations of ethanol.

Antineoplastic Agents↗
PubMed2001

Transcatheter intraarterial infusion of rt-PA for acute lower limb ischemia: results and complications.

PURPOSE: To determine the success and complication rates of intraarterial recombinant tissue-type plasminogen activator (rt-PA) infusion for the treatment of acute lower extremity artery and bypass graft occlusions. MATERIALS AND METHODS: The results of 74 limbs in 70 patients (mean age, 66 y) treated with catheter-directed rt-PA infusion for the treatment of acute lower extremity ischemia were retrospectively evaluated. The group included 42 bypass grafts and 32 native arteries. All limbs were viable at presentation. The mean duration of symptoms was 11.9 days. rt-PA was infused for a mean of 27.9 hours for a mean total dose of 38.7 mg. Initial infusion rates of 3-6 mg/h were lowered to a preferred rate of 1.5 mg/h. Thrombolytic success was defined as 95% thrombolysis of an occluded segment with return of antegrade flow. Major bleeding complications were defined as any hemorrhagic event leading to surgery, extended or unexpected hospitalization, transfusion, death, intracranial hemorrhage, or a decrease in hemoglobin of 5 g/dL or in hematocrit of 15%. Thirty-day mortality and amputation rates were calculated. Patient characteristics and infusion parameters were evaluated as to whether they contributed to thrombolytic success or major bleeding events. RESULTS: Thrombolytic success was achieved in 64 limbs (86%). Major bleeding complications occurred in 33 (47%) patients. In 22 of these patients, bleeding occurred at a vascular puncture site, whereas remote bleeding occurred in seven patients. Remote bleeding complications included two retroperitoneal hematomas, two rectus sheath hematomas, one lower gastrointestinal hemorrhage, one episode of hemoptysis, and one dehiscence of a femoral-popliteal bypass graft revision. No parameters were found to be predictive of thrombolytic success, whereas a negative history of smoking, increasing duration of infusion, and a low preprocedural ankle-brachial index (ABI) were found to be associated with major hemorrhagic events. Four patients (6%) underwent amputation and one patient (1%) died, resulting in a 30-day amputation-free survival rate of 93%. CONCLUSION: Catheter-directed rt-PA infusion is effective in achieving thrombolysis. Despite a significant number of bleeding complications, 30-day mortality and amputation rates were favorable. Nonetheless, complication rates related to bleeding were not trivial and further evaluation with use of variable dosing regimens is indicated.

Adult↗
PubMed2001

Comparison of three mechanical thrombus removal devices in thrombosed canine iliac arteries.

PURPOSE: To assess and compare intimal and medial vascular damage caused by three mechanical wall-contact thrombectomy devices: Fogarty embolectomy catheter, Arrow-Trerotola peripheral thrombectomy device, and MTI-Castañeda over-the-wire brush. MATERIALS AND METHODS: Bilateral external iliac arteries of 15 canines were thrombosed before mechanical thrombolysis. Ten thrombosed arteries were randomly assigned to receive each device. Animals were sacrificed immediately, and histologic assessment of endothelial and medial damage in the vessels was performed. RESULTS: The vascular damage found with all devices extended into the tunica media. The Fogarty embolectomy catheter and the Arrow-Trerotola device caused significantly more damage than the Castañeda brush. CONCLUSION: All devices caused lesions extending into the media. Previous research has shown that the extent and depth of the vascular lesion may be contributing factors in promoting early atherosclerotic and accelerated hyperplastic intimal and medial changes. These findings warrant further study of these devices in an atherosclerotic model with longer follow-up.

Angiography↗
PubMed2000

Cytotoxicity of millimolar concentrations of ethanol on HepG2 human tumor cell line compared to normal rat hepatocytes in vitro.

PURPOSE: The antiproliferative effect of high concentrations of ethanol (80-100 mmol) on liver carcinoma is well known. However, the high concentrations of ethanol affect both tumor cells and normal hepatocytes. The present study was designed to determine the effect of low ethanol concentrations (0-10 mmol) on cell proliferation and cell death (apoptosis and necrosis) in a human tumor cell line HepG2 and in normal rat hepatocytes. METHODS: Primary cultures of normal rat hepatocytes and HepG2 cells cultures were used. Cells were incubated with increasing ethanol concentrations or without ethanol (control group) for 24 h and analyzed immediately (group I) or after an additional incubation time of 48 h without additional ethanol application (group II). Cell proliferation was determined by assessing 5-bromo-2'-deoxyuridine (BrdU) incorporation. Apoptosis was assessed by means of DNA fragmentation and cysteine aspartate-specific protease (caspase-3) activity. Necrosis was analyzed by quantification of lactate dehydrogenase (LDH) release into culture medium. RESULTS: Twenty-four h exposure to 1 mmol ethanol inhibited cell proliferation in HepG2 cells by 75% (P < 0.05), while it remained unaltered in rat hepatocytes. The effect of ethanol persisted for another 48 h where cell proliferation was 5% of control in HepG2 cells and 70% of control in rat hepatocytes (P < 0.005). After 24 h incubation with 1 mmol ethanol 28% of HepG2 cells and 12% of rat hepatocytes showed DNA fragmentation as sign of apoptosis (P < 0.001). In group II 39% of HepG2 cells and 26% of rat hepatocytes were apoptotic (P < 0.001). Caspase-3 activation progressively increased after ethanol treatment in HepG2 cells and rat hepatocytes. The first significant difference was observed after 4 h (activity in HepG2 was 68% higher than in rat hepatocytes) and was maximum after 10 to 12 h where the activity in HepG2 was 180% of the activity in rat hepatocytes. Lactate dehydrogenase release into culture medium as an indicator of necrosis in HepG2 cells, increased from 0.5% in group I to 12% in group II, and from 0.1% to 8% in rat hepatocytes (P < 0.005). Increasing ethanol concentration to 10 mmol increased necrosis to 75% in HepG2 cells, and to 45% in rat hepatocytes (P < 0.05) whereas the effects on cell proliferation and apoptosis were not significantly different. CONCLUSIONS: Small ethanol concentrations (equivalent to 1 mmol) inhibit cell proliferation and increase apoptosis more strongly in HepG2 cells than in normal rat hepatocytes. These findings suggest the use of 1 mmol ethanol as a treatment for hepatocellular carcinoma because this mainly affects tumor cells but not surrounding normal tissue.

Alcohol Dehydrogenase↗
PubMed2000

Short exposure to millimolar concentrations of ethanol induces apoptotic cell death in multicellular HepG2 spheroids.

PURPOSE: We have shown previously that 1 mM ethanol reduces cell proliferation and increases apoptosis in monolayers of human hepatocellular carcinoma (HepG2) cells. However, in vivo liver tumors are usually three-dimensional and multicellular. The purpose of this study was therefore to determine the effect of ethanol in multicellular tumor spheroids (MCTS) as a model system in vitro. METHODS: After the application of 1 mM ethanol for 24 h and 48 h, viable, apoptotic and necrotic cells within MCTS were stained with specific fluorescent dyes, and their amount and distribution within the MCTS were assessed by confocal laser scanning microscopy. To evaluate the effect on HepG2 cell migration and cell proliferation, the outgrowth potential after 1 week in culture was evaluated. RESULTS: As assessed by YO-PRO-1 staining, ethanol increased the number of apoptotic cells from 21.5 units (U) in control spheroids to 364 U and 482.2 U after 24 h and 48 h in ethanol-treated spheroids, respectively (P < 0.001). Merocyanine staining fluorescence increased from 10.7 U in the control to 122 U after 24 h and 293.2 U after 48 h (P < 0.001). Cell viability, as determined by staining with the acetoxymethyl ester of calcein, decreased from 578.5 U in the control to 236 U and 73.4 U after 24 h and 48 h of ethanol exposure respectively (P < 0.001). Necrosis showed an increase from 2 U in control to 24.9 after 24 h and 54 U after 48 h. MCTS treated with ethanol showed almost complete inhibition of outgrowth potential after 1 week in culture, compared to controls (P < 0.005). CONCLUSIONS: Small concentrations of ethanol (1 mM) induced apoptosis in HepG2 MCTS with a concomitant inhibition on outgrowth potential, accompanied with a low degree of necrosis. These findings suggest that low concentrations of ethanol may already be sufficient for the treatment of hepatocellular carcinoma.

Antineoplastic Agents↗
PubMed2000

Assessment of a polyester-covered nitinol stent in an atherosclerotic swine model.

PURPOSE: To evaluate the short-term patency and healing characteristics of the Cragg EndoPro covered stent in an atherosclerotic model as one of the Food and Drug Administration requirements before possible approval of the device for human use in the United States. MATERIALS AND METHODS: Seventeen self-expanding stent-grafts were placed in the aorta and right and left iliac arteries of six Yucatan microswine exposed to a regimen of accelerated atherosclerosis. The stent-grafts were constructed from nitinol wire formed into a tubular zigzag configuration. The stent frame was covered by a thin woven polyester fabric tube, with medium permeability, available in multiple diameters and lengths. The animals were killed at 24 hours, 3 months, and 6 months. Assessment was done by angiography and histology. RESULTS: All stents were patent immediately after deployment. Two stents were occluded at follow-up, indicating an 88% patency rate. Minor lumen narrowing was found at the follow-up intervals. Histologic examination revealed a mixture of mature and immature endothelial cells lining both the native and stented regions in all vessels examined. The new endoluminal surface was composed primarily of fibrocollagen and elastic fibers and smooth muscle cells. Intimal thickness was inversely correlated to medial thickness. Medial compression with atrophy was observed routinely with rare necrosis. Complete tissue ingrowth was seen by 3 months. The degree of vascular inflammation increased over time, as well as the foreign body giant cell reaction to the polyester fabric. CONCLUSION: The patency rate does not appear to be better than that with angioplasty or noncovered stent placement in the studied time frame. The progressive vascular inflammatory changes noted should be further investigated in longer-term animal trials to ensure its safety in humans because this device is meant to be permanent.

Alloys↗
PubMed2000

Pharmacomechanical thrombolysis with use of the brush catheter in canine thrombosed femoropopliteal arterial PTFE bypass grafts.

PURPOSE: To assess the efficacy, acute endothelial changes, and distal arterial emboli after use of the Cragg thrombolytic brush catheter in mature thrombosed polytetrafluoroethylene (PTFE) femoropopliteal arterial grafts in canines. MATERIALS AND METHODS: PTFE femoropopliteal arterial grafts were implanted in 10 canines and were allowed to mature for approximately 4 weeks. The grafts were thrombosed by mechanical means and allowed to remain thrombosed for 24-72 hours. Through a left carotid cut-down, standard Seldinger arterial puncture was performed, followed by catheterization of the thrombosed graft. A soft, low-speed, brush (6 mm in diameter) aided by preprocedure pulse-spray urokinase infusion was utilized for thrombolysis. The native vessels, just proximal and distal to the anastomosis, were evaluated microscopically for endothelial damage. Arteriography was used for assessment of distal embolus. RESULTS: All grafts were successfully thrombosed before thrombolysis. One graft could not be traversed with a wire and catheter and was, therefore, not treated. Immediate preprocedure pulse-spray urokinase infusion in the remaining nine grafts did not reconstitute antegrade flow in any instance and left significant amounts of residual thrombus in all treated grafts. Mechanical brush thrombolysis reconstituted antegrade flow in all nine treated grafts and complete graft thrombolysis was obtained in most. This was accomplished in a mean time of less than 4 minutes. Emboli were noted angiographically in 67% of cases. Histologic studies showed vessel wall damage limited to the intima or media in 67% of anastomoses. CONCLUSION: This method offers a simple and rapid means of recanalizing thrombosed PTFE femoropopliteal arterial grafts in the studied model. This technique provides a means of rapidly "debulking" most intragraft thrombi. This may result in a shorter course of thrombolytic infusion. Potential benefits may include shortening the total treatment time and decreasing morbidity and cost associated with percutaneous thrombolysis. The occurrence of distal emboli in a majority of cases is a concerning limitation of this technique.

Animals↗
PubMed1999

Effects of doxorubicin, mitomycin C, and ethanol on Hep-G2 cells in vitro.

There are conflicting results for experiments aimed at determining whether anticancer drug therapy of human hepatocellular carcinoma prolongs the survival rate effectively. The purpose of this study was to assess the effect of low concentrations of doxorubicin, mitomycin C, and ethanol on cell replication (cell number and proliferation), and cell apoptosis of cultured human hepatocellular carcinoma (Hep-G2) cells. After 1 day of exposure doxorubicin inhibited cell replication initially by 72%, but a partial recovery of the cell number was observed. Mitomycin C inhibited to the same extent but without recovery. Ethanol reduced the cell number even further, the maximum inhibition (12 days after exposure) being 96.4%. After 3 days of exposure all three agents stopped cell replication at a level of 2%-4% of the control (P < 0.001). Cell apoptosis was activated most strikingly by mitomycin C (5 microg/ml) after 1 day of exposure and by ethanol (150 microl/ml) after 3 days of exposure. Two-way repeated-measures analysis of variance showed statistically significant differences, with ethanol being the most significant followed by mitomycin C doxorubicin, and the control (P < 0.01). Thus, a low dose of ethanol combined with an exposure time of up to 3 days appears to be an effective regimen to control growth of human hepatocellular carcinoma cells in vitro. The strong induction of apoptosis by ethanol might be of additional benefit for a local application in vivo.

Analysis of Variance↗
PubMed1995

Angioplasty-induced pseudoaneurysm successfully treated with a Palmaz stent. A case report.

Pseudoaneurysm formation and vessel rupture are considered rare complications of percutaneous transluminal angioplasty (PTA), and few reported cases exist in the literature. The true incidence of pseudoaneurysm formation is unknown, for follow-up angiography is not routinely performed unless symptoms recur or persist. Currently, the only intervention widely accepted for angioplasty-induced pseudoaneurysm involves surgical excision or repair. The authors describe a case of successfully treated pseudoaneurysm with a noncovered stent.

Aneurysm, False↗
PubMed1993

[Malignant melanoma of the nasal cavities. Our experience from two cases].

Malignant Melanoma of the nasal cavity is a rare occurrence. Its clinical manifestations at beginning are non-specific and its macroscopical appearance is variable due to the several pigmentation tonalities which render sometimes difficult the diagnosis. The confirmed diagnosis result from the histopathologic study of the tissue. The treatment is surgery, when the cases are operable, and radiotherapy, chemotherapy and immunotherapy either as adjuvant or as palliative management in inoperable cases.

Adult↗
PubMed1990

Prostatic urethroplasty with balloon catheter as a nonsurgical alternative for prostatic hyperplasia.

Prostatic urethroplasty with balloon catheter is a new interventional uroradiological procedure that appears promising in treating benign prostatic hyperplasia in selected patients. As with many of the interventional radiographic procedures, it reduces the cost of therapy, it is associated with very low morbidity in an outpatient setting, and it can be performed in almost any patient, regardless of their medical condition. The recovery period is minimal. The procedure is easy to perform, but certain guidelines have to be followed to avoid complications. The workup of these patients is relatively the same as a patient undergoing surgical intervention. The patient needs to be thoroughly assessed to exclude the possibility of prostatic malignancy.

Catheterization↗
PubMed1989

The importance of separation of prostatic lobes in relief of prostatic obstruction by balloon catheter urethroplasty: studies in dogs and humans.

We performed balloon urethroplasty in six older normal dogs and 10 patients with benign prostatic hypertrophy to establish the mechanism by which this technique results in relief of bladder outlet obstruction. Thirty-millimeter balloon catheters were used in both the animal and human studies. Autopsy studies showed disruption of the anterior prostatic commissure in four of the six dogs, disruption of both anterior and posterior commissures in one dog, and no disruption in the remaining dog. In all 10 patients, cystoscopy and urethrography showed disruption of the anterior commissure. Separation of the prostatic lobes by disruption of the prostatic commissures may be the most important mechanism by which balloon urethroplasty relieves urethral obstruction.

Animals↗
PubMed1988

Balloon dilatation of the prostate for treatment of benign hyperplasia.

Trasurethral balloon dilatation of the prostate is a safe and simple procedure. It can be performed on an outpatient basis using topical anesthesia and sedation. The morbidity is minimal. The short-term results are encouraging. Prospective randomized studies are needed to determine the role of transurethral dilatation in the treatment of benign prostatic hyperplasia.

Catheterization↗