Biomedical subjects

C Riquelme

Publications and source records attributed to C Riquelme.

9 recordsLinked to original sources

PubMed2003

Giant spinal perimedullary fistula in hereditary haemorrhagic telangiectasia: diagnosis, endovascular treatment and review of the literature.

Hereditary hemorrhagic telangiectasia (HHT, Rendu-Osler-Weber disease) is a vascular disorder with dominant autosomal transmission characterised usually by multiple mucocutaneous and visceral abnormalities. Neurological manifestations due to the primary involvement of spinal cord by vascular malformations are rare. We present a young man with HHT associated with a central nervous system arteriovenous malformation and a giant perimedullary fistula, that was manifested as progressive myelopathy. The diagnosis was made coupling magnetic resonance imaging to selective spinal arteriography. The therapeutic option was endovascular treatment by mechanically detachable coils which resulted in full exclusion of the fistula with full improvement of symptoms. During follow-up a stable clinical and morphological outcome was achieved. Clinical manifestations in HHT, with emphasis on neurological symptoms, are reviewed as well as the therapeutic options to deal with giant perimedullary fistula.

Adolescent↗

PubMed2003

Posterior cervical haemangiopericytoma with intracranial and skull base extension. Diagnostic and therapeutic challenge of a rare hypervascular neoplasm.

Haemangiopericytomas are rare hypervascular tumors arising from pericytes. They may occur anywhere in the body, but posterior cervical location is rather uncommon. A case of posterior cervical haemangiopericytoma with posterior fossa and temporal bone extension is reported. Although the patient had undergone preoperative endovascular embolization and surgical resection on three separate occasions, control of the skull base extension was not successful. Following endovascular embolization combined with radiotherapy, the patient has been asymptomatic for 48 months. Angiographic features may help in differentiating haemangiopericytomas from other hypervascular lesions. Preoperative endovascular embolization is recommended due to the pronounced tendency for haemorrhage throughout biopsy and surgical procedures.

Cervical Vertebrae↗

PubMed2001

Coronavirus derived expression systems.

Both helper dependent expression systems, based on two components, and single genomes constructed by targeted recombination, or by using infectious cDNA clones, have been developed. The sequences that regulate transcription have been characterized mainly using helper dependent expression systems and it will now be possible to validate them using single genomes. The genome of coronaviruses has been engineered by modification of the infectious cDNA leading to an efficient (>20 microg ml(-1)) and stable (>20 passages) expression of the foreign gene. The possibility of engineering the tissue and species tropism to target expression to different organs and animal species, including humans, increases the potential of coronaviruses as vectors. Thus, coronaviruses are promising virus vectors for vaccine development and, possibly, for gene therapy.

Coronavirus↗

PubMed2001

Chemonucleolysis of lumbar disc herniation with ethanol.

PURPOSE: To demonstrate the efficiency of the treatment of the lumbar disk herniation (LDH) with absolute alcohol. MATERIALS/METHODS: From June 1997 to September 2000, 118 patients with 126 LDH, 69 males and 49 females, aged 19 to 77 (mean age: 51.1 years) were treated with absolute alcohol nucleolysis. In 75 cases, the LDH were parasagittal, in 30 foraminal, in 17 medial and in 4 extraforaminal. In most cases, the sensitive symptoms and motor or reflex abnormalities corresponded to the lumbar disc herniation level. Nucleolysis was made in ambulatory condition and each patient underwent general anesthesia. All procedures were performed in surgical conditions and controlled under digital fluoroscopy. The disc puncture was laterally made at the junction of middle and posterior thirds of the disc, under strict lateral fluoroscopic control. A discogram was obtained before ethanol injection. Injection dose of absolute alcohol was 0.4 ml. The realization time was about 15 minutes. RESULT: Total improvement of symptoms was obtained in 97.55% of cases. Two patients remained with low-back pain and the failure treatment rate was 0.84% (1 case). CONCLUSION: Nucleolysis with ethanol is a very effective, safe and low cost treatment for any kind of LDH, that allows to treat several levels during the same procedure, and can be repeated several times. Nucleolysis with ethanol can be made in ambulatory condition and be proposed to patients who refuse surgical treatment and have allergic background.

Adult↗

PubMed2000

Antisense inhibition of decorin expression in myoblasts decreases cell responsiveness to transforming growth factor beta and accelerates skeletal muscle differentiation.

Decorin is a member of the family of the small leucine-rich proteoglycans. In addition to its function as an extracellular matrix organizer, it has the ability to activate the epidermal growth factor receptor, and it forms complexes with various isoforms of transforming growth factor beta (TGF-beta). Decorin is expressed during skeletal muscle differentiation and is up-regulated in dystrophic muscle. In this study we investigated the role of decorin in TGF-beta-dependent inhibition of myogenesis. To probe the function of decorin during myogenesis, C(2)C(12) myoblasts were stably transfected with a plasmid expressing antisense decorin mRNA. The resulting inhibition of decorin expression led to the expression of myogenin, a master transcription factor for muscle differentiation, under growth conditions and accelerated skeletal muscle differentiation as determined by the expression of creatine kinase. In contrast myogenin expression was inhibited by adenovirally induced decorin expression or by adding exogenous decorin. Reduced synthesis of decorin resulted in a 7-fold decreased sensitivity to TGF-beta-mediated inhibition of myogenin expression. In contrast, adenovirally induced decorin expression in wild type cells resulted in a 5-fold increased sensitivity to TGF-beta-mediated inhibition of myogenin expression. Transfection studies with the TGF-beta-dependent promoter of the plasminogen activator inhibitor-1 coupled with luciferase revealed that the transducing receptors for TGF-beta1 and TGF-beta2 were involved in the different responses of wild type and antisense decorin myoblasts. These results demonstrate that a reduction of decorin expression or of decorin availability results in a decreased responsiveness to TGF-beta. These findings strongly suggest a new role for decorin during skeletal muscle terminal differentiation by activating TGF-beta-dependent signaling pathways.

Animals↗

PubMed1999

MR imaging of coarctation of the aorta and its postoperative complications in adults: assessment with spin-echo and cine-MR imaging.

To evaluate the ability of ECG-gated spin-echo (SE)-MR imaging vs. cine-MR imaging to assess coarctation of the aorta, 11 patients aged 15-45 years, with known or suspected coarctation of the aorta, and five patients suspected of re-stenosis or postoperative false-aneurysms after coarctation repair were examined by multisection SE-MR imaging and single-section multiphase cine-MR imaging on a 1.0 Tesla device. Aortography was performed in 15, and surgery in 14 of these 16 patients. Qualitatively, the location, severity, and length of the coarctation were shown in all cases with MR imaging, as well as the relationship with the arteries arising from the aortic arch. The respective sensitivities and specificities in the assessment of severity of stenoses were 86% and 100% for SE MR images, and 100% and 100% for cine-MR images. Cine-MR imaging was superior to SE imaging in stenosis diameter assessment with contrast angiography as reference, as well as to identify the site of leakage in cases of postoperative pseudoaneurysm. Pre-stenotic dilation or post-stenotic aneurysm, collateral channels, and associated malformations were better identified on SE images. Quantitatively, a better stenosis diameter correlation was found between cine-MR images and angiography than between SE-MR images and angiography (r=0.99 vs. r=0.78; p=0.001 vs. p=0.004), related to overestimation of stenoses with SE-MR imaging. The use of a combination of spin-echo and cine-MR imaging correlates well with conventional angiographic findings in this small series of patients with coarctation of aorta or postoperative pseudoaneurysmal complications. Cine-MRI can provide anatomic information that is equivalent to angiography for surgical planning.

Adolescent↗

PubMed1999

[Efficacy of lumbar chemonucleolysis in the treatment of foraminal and extra-foraminal hernias].

A retrospective review of 1,200 nucleolyses performed over a three year period from January 1995 to December 1997 showed 116 discal treatments for foraminal and extra-foraminal localizations. The anatomic localization through the foramen and the intense clinical signs typify these anatomoclinical forms of lumbar hernia. In contrast with complex and disruptive surgical cure, percutaneous nucleolysis offers a precise and rapid method which can be performed in a very short time in outpatients with a success rate of 80%. Most localizations concern L3-L4 and L4-L5 hernias which give the best clinical outcomes.

Adult↗

PubMed1996

Association of Aeromonas hydrophila and Vibrio alginolyticus with Larval Mortalities of Scallop (Argopecten purpuratus)

A bacteriological study was carried out in a hatchery of Argopecten purpuratus located in northern Chile which had been affected by severe larval mortalities. The phenotypic characterization of the bacterial strains revealed that Vibrio alginolyticus was the predominant species isolated in the majority of samples taken from the different units of the hatchery (microalgae, swimming larvae, seawater of larval culture tanks, and a reservoir tank of 50-μm filtered seawater). However, the bacterial population of dying larvae was composed of only Aeromonas hydrophila strains which proved to be resistant to most of the chemotherapeutic agents tested. The bioassays conducted to evaluate the effect of these bacteria on larval survival showed that all of the isolated Vibrio and Aeromonas strains possessed a high degree of pathogenicity, since they produced dying larvae on concentrations ranging from 5.5 x 10(4) to 5.5 x 10(2) cells/ml. The possible virulence mechanism of these bacteria is discussed, as well as the potential use of drugs to prevent larval mortalities.

Journal Article↗

PubMed1996

Assessment of deep venous thrombosis in the lower limbs and pelvis: MR venography versus duplex Doppler sonography.

OBJECTIVE: This study was designed to compare the diagnostic value of MR venography and color Doppler sonography in the assessment of deep venous thrombosis. SUBJECTS AND METHODS: MR venograms and color Doppler examinations were obtained in 37 patients either with suspected deep venous thrombosis of the lower limbs or pelvis or with pulmonary embolism. Two-dimensional time-of-flight venography was used for all studies. MR and color Doppler data were collected prospectively and analyzed in a blinded manner. In a subset of 21 patients, MR venography and color Doppler sonography were prospectively compared with contrast-enhanced venography. RESULTS: When compared with contrast-enhanced venography, MR venography was 100% sensitive and 100% specific in the diagnosis of deep venous thrombosis above the knee. Color Doppler imaging depicted 13 of 15 cases of deep venous thrombosis and 5 of 6 venous examinations that had normal results, yielding a sensitivity and a specificity of 87% and 83%, respectively. The differences in sensitivity and specificity between MR venography and color Doppler sonography were not statistically significant. MR venography was 95% sensitive and 99% specific in detecting the extension of deep venous thrombosis, compared with the 46% sensitivity and 100% specificity of color Doppler sonography (differences in sensitivity, p < .01). MR images showed 29 collateral vessels, whereas only 21 were detected by contrast-enhanced venography (p < .04). CONCLUSION: MR venography seems to be more accurate than color Doppler sonography in detecting the extension of deep venous thrombosis. The positive diagnosis and extent of deep venous thrombosis can be easily detected and monitored by a noninvasive technique such as MR venography.

Adult↗