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Carlos Hernández

Publications and source records attributed to Carlos Hernández.

14 recordsLinked to original sources
PubMed2007

Silhouette coherence for camera calibration under circular motion.

We present a new approach to camera calibration as a part of a complete and practical system to recover digital copies of sculpture from uncalibrated image sequences taken under turntable motion. In this paper, we introduce the concept of the silhouette coherence of a set of silhouettes generated by a 3D object. We show how the maximization of the silhouette coherence can be exploited to recover the camera poses and focal length. Silhouette coherence can be considered as a generalization of the well-known epipolar tangency constraint for calculating motion from silhouettes or outlines alone. Further, silhouette coherence exploits all the geometric information encoded in the silhouette (not just at epipolar tangency points) and can be used in many practical situations where point correspondences or outer epipolar tangents are unavailable. We present an algorithm for exploiting silhouette coherence to efficiently and reliably estimate camera motion. We use this algorithm to reconstruct very high quality 3D models from uncalibrated circular motion sequences, even when epipolar tangency points are not available or the silhouettes are truncated. The algorithm has been integrated into a practical system and has been tested on more than 50 uncalibrated sequences to produce high quality photo-realistic models. Three illustrative examples are included in this paper. The algorithm is also evaluated quantitatively by comparing it to a state-of-the-art system that exploits only epipolar tangents.

Algorithms↗
PubMed2006

Gastrin induces leukocyte-endothelial cell interactions in vivo and contributes to the inflammation caused by Helicobacter pylori.

Gastric mucosal inflammation causes hypergastrinemia, and gastrin receptors have been detected in several leukocyte types. We have analyzed whether gastrin affects the leukocyte-endothelial cell interactions in vivo by monitoring leukocyte rolling, adhesion, and emigration in rat mesenteric venules using intravital microscopy. Mesenteric superfusion with exogenous gastrin increased these processes in a concentration- and time-dependent manner, effects prevented by the cholecystokinin (CCK)-2 receptor antagonists (proglumide, L-365,260) but not by the CCK-1 receptor antagonist devazepide. A similar response was induced by exogenous CCK or endogenously released gastrin. CCK-2 receptors were localized in mesenteric macrophages and polymorphonuclear leukocytes. This effect of gastrin is not modulated by somatostatin and is independent of the endogenous release of histamine. To analyze whether hypergastrinemia elicited by Helicobacter pylori (HP) modulates the inflammation induced by the germ, rats were chronically administered with an extract of a CagA+/VacA+ strain of HP. This protocol increased gastrinemia and induced an inflammatory response in the rat mesentery. Blockade of CCK-2 receptors attenuated this response and induced a qualitative change in the leukocyte infiltrate suggestive of a receding inflammatory process. Our results reveal a new proinflammatory role of gastrin that seems to contribute to the maintenance of the inflammation elicited by HP components.

Animals↗
PubMed2005

Transcriptional up-regulation of nNOS in the dorsal vagal complex during low endotoxemia.

The present study analyses the expression and distribution of neuronal nitric oxide synthase (nNOS) in the brainstem of animals pre-treated with Escherichia coli or Helicobacter pylori LPS, at doses that modulate gastric motor function. Systemic administration of H. pylori LPS prevented in a dose-dependent manner (5, 40 and 100 microg kg(-1), i.v.) the increase in intragastric pressure induced by 2-deoxy-D-glucose (200 mg kg(-1), i.v.) in urethane-anaesthetized rats. Quantitative analysis showed a significant increase in the amount of nNOS mRNA induced by E. coli or H. pylori LPS (2 h later), in a segment of the brainstem containing the dorsal vagal complex (DVC). Immunohistochemical studies showed nNOS presence in the DVC of vehicle-treated rats. Both E. coli (40 microg kg(-1), i.p.) and H. pylori LPS (100 microg kg(-1), i.p.) significantly increased (2 h later) the number of nNOS immunoreactive cells in this area, mainly at the most rostral level. The present study shows that systemic administration of E. coli or H. pylori LPS induces a transcriptional up-regulation of the nNOS in the DVC of the brainstem and suggests a role for NO synthesis in this area in the control of gastric motor function under endotoxemia.

Animals↗
PubMed2005

[Surgical treatment of renal adenocarcinoma with venous thrombus].

OBJECTIVES: To analyze therapeutic management and survival of renal adenocarcinoma with tumor venous extension treated by surgery in our experience. METHODS: We retrospectively evaluate a series of 29 cases of renal adenocarcinoma with venous thrombus who underwent radical nephrectomy and thrombectomy from January 1986 to November 2003. Mean age was 63.4 11.9 (29-79) years. 23 patients were males (79%) and 6 (21%) females. 17 (59%) patients had the tumor in the right kidney and 12 (42%) in the left kidney. Tumor thrombus level was: Level I (renal vein-inferior vena cava) 13 (45%), Level II (infrahepatic vena cava) 9 (31%), Level III (retrohepatic vena cava/suprahepatic) 3 (10%), and Level IV (auricula) 4 (14%). 92% of the cases presented perirenal fat involvement. Survival analysis was performed including 24 cases of the 29. We analyzed overall and cancer-specific survival, as well as possible influence of tumor thrombus level, fat involvement, and tumor grade as prognostic factors. RESULTS: Mean tumor size was 8.15 +/- 2.25 cm (5-13). Surgical approach was purely abdominal in 23 cases (79%) and thoraco-phreno-laparotomy in 6 (21%). Hepatic mobilization maneuvers and hepatic pedicle clamping were performed in 5 (17%) patients. Venous clamping was: renal-cava 13 cases (44%), triple clamping I1 (37%) (9 infrahepatic and 2 suprahepatic), and supradiaphragmatic-auricula 5 (17%). Conventional extracorporeal circulation (CEC) with moderate hypothermia (26-28 degrees C) was employed in 4 cases and CEC with heart arrest (4 min) in one. Mean follow-up was 52 months. At the time of review 9 patients were alive, 11 had died from tumor and 4 had died from other causes. Mean overall survival was 71 +/- 12 months and cancer specific survival 86 +/- 14 months. Neither renal fat involvement (p=0.6) nor tumor thrombus level (p = 0.9) were prognostic factors for survival in the univariant analysis, but tumor grade was (p = 0.03). CONCLUSIONS: Patients with venous tumor extension without lymph node involvement or metastasis should be treated by radical surgery with complete excision of the tumor thrombus. Tumor grade was a prognostic factor for survival, but venous involvement level and presence of perirenal fat involvement were not.

Adenocarcinoma↗
PubMed2004

Radiological assessment of penile prosthesis: the role of magnetic resonance imaging.

Penile implants offer a dependable way of restoring erections in virtually all motivated patients. The satisfaction rate among both patients and partners using these devices is high. Advances in technology have reduced the infection rate and increased the mechanical reliability of these products. However, too often, urologists do not present this option with the same authority as other treatments. The reason is fear of complications and lack of expertise in managing them. Although they are not very frequent, complications may be catastrophic. The most significant postoperative complication associated with the implant surgery is infection of the device, which is quite frequent, but some other important complications are distal and proximal perforation of the albuginea, SST deformity, "S-shaped" deformity of the penis, erosion of a component, and mechanical malfunction of the device. The best way to manage complications is to prevent them, but we do not have many diagnostic tools available. Diagnosis is based on clinical history and physical examination, but imaging techniques are also needed to explore the prosthesis "in situ" to plan the surgical approach if it is needed. In this article we review the different imaging techniques used for the diagnosis of complications of prosthetic surgery of the penis, including conventional radiology, use of sonography, the role of CT scan and the magnetic resonance imaging (MRI) of the penile prosthesis. We conclude that MRI is the most valuable method for the diagnosis of penile prosthesis complications. It is not an ionizing radiation imaging method and has the unique feature among imaging techniques of demonstrating penile anatomy in three orthogonal planes. It is superior to any other imaging method in the definition of soft tissue contrast.

Humans↗
PubMed2004

Synthesis of nitric oxide in postganglionic myenteric neurons during endotoxemia: implications for gastric motor function in rats.

We have investigated the mechanisms underlying acute changes in gastric motor function triggered by endotoxemia. In fundal strips from rats pre-treated with endotoxin (40 microg/kg, i.p. 30 min), mechanical activity was analyzed and the source of nitric oxide (NO) was visualized by confocal microscopy of tissue loaded with the fluorescent dye DAF-FM. NOS expression was determined by quantitative RT-PCR and Western blot, and enzyme activity by the citrulline assay. Strips from endotoxin-treated rats were hypo-contractile. This was prevented by pre-incubation with the neurotoxin tetrodotoxin, the gangliar blocker hexamethonium, or non-selective and neuronal-specific NOS inhibitors (L-NOARG and TRIM, respectively). The soluble guanylyl cyclase (sGC) inhibitor ODQ and the inhibitor of small conductance Ca2+-activated K+ channels apamin prevented relaxation induced by endotoxin, nicotine, exogenous NO (DETA-NONOate), and the NO-independent sGC activator BAY 41-2272. NO synthesis was observed in neuronal soma, axons, and nerve endings of the myenteric plexus in the fundus of endotoxin-treated rats and was prevented by L-NAME, tetrodotoxin, and hexamethonium. nNOS and iNOS mRNA and protein contents were unchanged. Our findings demonstrate synthesis of NO in post-ganglionic myenteric neurons during early endotoxemia that mediates gastric hypo-contractility. The effect of NO is mediated via sGC and small conductance Ca2+-activated K+channels.

Animals↗
PubMed2004

Efficacy of sildenafil citrate at 12 hours after dosing: re-exploring the therapeutic window.

OBJECTIVE: This open-label study investigated the efficacy of sildenafil citrate at 12 hours postdose among prior treatment responders. PATIENTS AND METHODS: Eight 100-mg doses of sildenafil were provided to 40 eligible patients with erectile dysfunction (ED), who were to record the results of each sexual attempt in a patient diary. Each patient was instructed to make a sexual attempt at 1 and 12 hours postdose on 4 occasions (part 1) and only at 12 hours postdose on 4 subsequent occasions (part 2). RESULTS: Of 40 enrolled patients, 34 (85%) completed the study. In these evaluable patients, 97% and 74% of patients achieved erections that resulted in successful intercourse at 1 hour and 12 hours postdose, respectively. There was a nonsignificant reduction in the percentage of responders at 12 hours during part 1 versus part 2 of this study (71% versus 78%). CONCLUSIONS: This study demonstrates that, in the majority of these patients with ED, sildenafil remains clinically active 12 hours after administration. Larger studies may be necessary to confirm and clarify the therapeutic window of sildenafil.

Adult↗
PubMed2004

[Methodology in infertility studies. Outcome measures for therapeutic success. When should we consider that has been a change in semen quality?].

OBJECTIVES: Surgery has been largely indicated for varicocele with the aim of improving semen parameters in male patients with subfertility or infertility. However, the criteria for therapeutic success in which its usefulness has been based on have never been clear. Our objective was to analyze current criteria for therapeutic success after surgical treatment of varicocele, studying in depth the possible influence of varicocele on semen quality, its impact on fertility, and possible advantages of treatment. METHODS: We reviewed a group of original articles, systematic reviews, and metanalysis on the issue after MEDLINE search. We mainly focus on randomized placebo-controlled prospective studies the aim of which was to evaluate the improvement in semen quality and/or pregnancy rates in subfertile/infertile couples after treatment of varicocele. CONCLUSIONS: There is great study heterogeneity, both in methods and possible interpretation of results. Although it seems treatment of varicocele may improve some semen quality parameters, it does not seem to represent an effective treatment for male subfertility.

Humans↗
PubMed2003

Regulation of hypoxia-inducible factor-1alpha by nitric oxide through mitochondria-dependent and -independent pathways.

Nitric oxide (NO) has been reported both to promote and to inhibit the activity of the transcription factor hypoxia-inducible factor-1 (HIF-1). In order to avoid the pitfalls associated with the use of NO donors, we have developed a human cell line (Tet-iNOS 293) that expresses the inducible NO synthase (iNOS) under the control of a tetracycline-inducible promoter. Using this system to generate finely controlled amounts of NO, we have demonstrated that the stability of the alpha-subunit of HIF-1 is regulated by NO through two separate mechanisms, only one of which is dependent on a functional respiratory chain. HIF-1alpha is unstable in cells maintained at 21% O(2), but is progressively stabilized as the O(2) concentration decreases, resulting in augmented HIF-1 DNA-binding activity. High concentrations of NO (>1 microM) stabilize HIF-1alpha at all O(2) concentrations tested. This effect does not involve the respiratory chain, since it is preserved in cells lacking functional mitochondria (rho(0)-cells) and is not reproduced by other inhibitors of the cytochrome c oxidase. By contrast, lower concentrations of NO (<400 nM) cause a rapid decrease in HIF-1alpha stabilized by exposure of the cells to 3% O(2). This effect of NO is dependent on the inhibition of mitochondrial respiration, since it is mimicked by other inhibitors of mitochondrial respiration, including those not acting at cytochrome c oxidase. We suggest that, although stabilization of HIF-1alpha by high concentrations of NO might have implications in pathophysiological processes, the inhibitory effect of lower NO concentrations is likely to be of physiological relevance.

Cell Hypoxia↗
PubMed2003

Low endotoxemia prevents the reduction of gastric blood flow induced by NSAIDs: role of nitric oxide.

1 The role of nitric oxide (NO) in the effects of low endotoxemia on gastric damage and blood flow has been evaluated in indomethacin-treated rats. 2 Pretreatment (-1 h) with endotoxin (40 micro g kg(-1)) reduced gastric damage induced by indomethacin (20 mg kg(-1)) in conscious rats. 3 Endotoxin prevented the reduction in gastric blood flow (laser Doppler flowmetry) induced by indomethacin in pentobarbital-anaesthetised rats. 4 Pretreatment with an NO-synthase (NOS) inhibitor (L-NAME, 1 mg kg(-1)) reversed the protective effect of endotoxin on gastric blood perfusion. 5 Endotoxin did not modify the expression of mRNA for endothelial NOS or inducible NOS in the gastric corpus when evaluated 1 h postinjection. However, a 3.8-fold increase in inducible NOS mRNA and a 61% reduction in endothelial NOS mRNA were observed in the gastric corpus 4 h after endotoxin administration. 6 Evaluation of both total and Ca(2+)-dependent NOS activity by analysing the rate of conversion of L-arginine to L-citrulline in gastric corpus homogenates showed no differences between animals treated with endotoxin and those treated with saline 1 or 4 h beforehand. Ca(2+)-independent NOS activity was almost non-apparent in control as well as in endotoxin-treated rats at all the time points analysed. 7 Low endotoxemia preserves blood perfusion and protects the gastric mucosa against the deleterious effects of indomethacin through the endogenous NO release. NO synthesis in response to endotoxin does not involve the inducible NOS, but probably depends on the post-translational/biochemical regulation in vivo of a Ca(2+)-dependent NOS, most probably endothelial NOS.

Animals↗
PubMed2002

Interleukin 1 beta-induced inhibition of gastric acid secretion involves glutamate, NO and cGMP synthesis in the brain.

This study examines the role of a central pathway involving glutamate receptors, nitric oxide (NO) and cGMP in the acute inhibitory effects of central interleukin 1beta on pentagastrin-stimulated acid production.The acid-inhibitory effect of central interleukin 1beta was prevented by intracisternal (i.c.) microinjections of interleukin 1beta together with the NMDA receptor antagonist, dizocilpine maleate (MK-801). Intracisternal co-administration of the nitric oxide synthase inhibitor, N(G)-nitro- L-arginine methyl esther ( L-NAME) or 1H-[1,2,4]oxazodiolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase (sGC) blocker, both reversed the hyposecretory effect of central interleukin 1beta. Peripheral administration of endotoxin significantly reduced pentagastrin-stimulated gastric acid secretion. I.c. pre-treatment with the interleukin 1 receptor antagonist, IL-1ra, failed to restore acid secretory responses in these rats. In addition, endotoxin did not modify the levels of endogenous mRNA for IL-1beta in the brainstem. We conclude that central glutamate receptors are involved in the acid inhibitory effect of centrally administered interleukin 1beta. This central pathway involves synthesis of NO, which acts on the enzyme sGC. However, endogenous interleukin 1beta does not seem to be involved in the inhibition of gastric acid secretion elicited by peripheral endotoxin.

Animals↗
PubMed2002

Downregulation of nNOS and synthesis of PGs associated with endotoxin-induced delay in gastric emptying.

A single intraperitoneal injection of endotoxin (40 microg/kg) significantly delayed gastric emptying of a solid nutrient meal. Blockade of nitric oxide synthase (NOS) with 30 mg/kg ip N(G)-nitro-L-arginine methyl ester or 20 mg/kg ip 7-nitroindazole [neuronal NOS (nNOS) inhibitor] significantly delayed gastric emptying in control animals but failed to modify gastric emptying in endotoxin-treated rats. Administration of 2.5, 5, and 10 mg/kg ip N(6)-iminoethyl-L-lysine [inducible NOS (iNOS) inhibitor] had no effect in either experimental group. Indomethacin (5 mg/kg sc), NS-398 (cyclooxygenase-2 inhibitor; 10 mg/kg ip), and dexamethasone (10 mg/kg sc) but not quinacrine (20 mg/kg ip) significantly prevented delay in gastric emptying induced by endotoxin but failed to modify gastric emptying in vehicle-treated animals. Ca(2+)-dependent NOS activity in the antrum pylorus of the stomach was diminished by endotoxin, whereas Ca(2+)-independent NOS activity was not changed. In addition, decreased nNOS mRNA and protein were observed in the antrum pylorus of endotoxin-treated rats. Our results suggest that downregulation of nNOS in the antrum pylorus of the stomach and synthesis of prostaglandins mediate the delay in gastric emptying of a solid nutrient meal induced by endotoxin.

Animals↗
PubMedDate not supplied

Tamsulosin: effect on quality of life in 2740 patients with lower urinary tract symptoms managed in real-life practice in Spain.

OBJECTIVE: To investigate the influence of tamsulosin treatment on the severity of lower urinary tract symptoms (LUTS) and the impact on quality of life (QoL), including daily life activities and mental well being, in real life practice in Spain. METHODS: 2740 LUTS patients aged 45-75 years who visited a urologist office in Spain received tamsulosin 0.4 mg o.d.. At baseline, after 3 months and after 6 months of treatment a questionnaire was completed by the urologist and the patient. The urologist estimated some aspects of the patient's QoL related to his LUTS. The International Prostate Symptom Score (I-PSS) was used to assess the severity of LUTS, while the BPH-Specific Interference with Activities (BSIA) and the Total Mental Health Rate assessed the impact on daily life activities and psychological well being respectively. RESULTS: After 3 months of treatment tamsulosin significantly improved the mean total I-PSS compared to baseline. After 6 months, the mean total I-PSS was reduced by 11.0 points from a baseline score of 20.3 (> 50% reduction). Tamsulosin also significantly improved the mean total BSIA score and the mean Total Mental Health Rate. These observations were confirmed by the urologists' assessment of the patient's condition: an increase of more than 50% of patients with no or mild voiding and filling LUTS and an increase of 45% of patients with no or only a small interference of their LUTS with daily life activities. The withdrawal rate due to adverse reactions was 2.4%. CONCLUSION: This study shows that tamsulosin improves LUTS and their impact on the patient's QoL and daily life activities, in the opinion of both the patients and the urologists.

Activities of Daily Living↗