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J Contreras

Publications and source records attributed to J Contreras.

At least 19 recordsLinked to original sources
PubMed2006

Conservative treatment with transurethral resection, neoadjuvant chemotherapy followed by radiochemotherapy in stage T2-3 transitional bladder cancer.

PURPOSE: Organ preservation has been investigated in patients (p) with infiltrating transitional cell carcinoma (TCC) of the bladder over the past decade as an alternative to radical cystectomy. This is a trimodal schedule study, including transurethral resection of bladder tumor (TURB), neoadjuvant chemotherapy and concomitant radiochemotherapy (RTC). PATIENTS AND METHODS: From April 1996 until August 2005, 29 evaluable patients (p) with T2-T3NXM0 bladder cancer were enrolled. After a transurethral resection of bladder tumor (TURB), we administered 2 cycles of induction chemotherapy with CMV (15 p) or Gemcitabine-Cisplatin (14 p) followed by radiotherapy 45 Gy 1.8 Gy/fraction and two cycles of concomitant cisplatin 70 mg/m(2). 2-3 weeks later, a cystoscopy with tumor-site biopsy was performed. If complete histological response, p were treated with consolidation radiotherapy until 64.8 Gy. For p with residual or recurrent tumor, cystectomy was performed. RESULTS: We included 28 men and 1 women (median age 63, range 39-72 years) with PS (ECOG) 0-1. The stage was: 21 p T2; 6 p T3a; and 2 p T3b. Toxicity was higher in CMV compared with Gem- Cis: grade (3/4) neutropenia 4/15 (26%) vs 1/14 (7%); febrile neutropenia 3/15 (20%) vs 1/14 (7%); grade (3/4) trombocytopenia 2/15 (13%) vs 1/14 (7%). Toxicities with concomitant RCT were low-moderate: urocystitis (26%) and enteritis (18%). RESPONSE: microscopically complete TURB was obtained in 20 p (69%), but not in 9 p (31%) (7 microscopic, and 2 macroscopic residual tumor). We found a complete histologic response after induction RCT in 25 p (86%). After a median follow-up of 69.4 months (m) (range: 8-97.7), there were 8 deaths, with a overall survival of 72%. Furthermore 14 of 29 p (48%) were alive with intact bladder, and median survival time with intact bladder was 63.6 m (50.1-77.2); were predictive of best outcome T2 stage vs T3 (p < 0.0001), and complete histologic resection in initial TURB vs residual tumor (p = 0.0004). CONCLUSIONS: Combined treatment provide high response rates and can be offered as an alternative option to radical cystectomy in selected patients with TCC. Patients with T2 stage and complete histologic resection in initial TURB had the best outcome.

Adult↗
PubMed2006

Doppler ultrasonographic and scintigraphic assessment of an auxiliary heterotopic liver transplantation with portal vein arterialization in pigs.

OBJECTIVE: Our aim was to evaluate liver graft integrity and function using scintigraphy and ultrasonography in a porcine model of auxiliary heterotopic liver transplantation with portal vein arterialization (AHLT-PVA). MATERIALS AND METHODS: Using Doppler ultrasonography we evaluated eight AHLT-PVA by parenchymal echogenicity, portal and arterial anatomy, and portal and biliary system flow. Two types of scintigraphy were performed: microaggregated human albumin colloid scintigraphy and diisopropyl iminodiacetic acid (DISIDA) scintigraphy, both labeled with 99mTc. RESULTS: The animals were distributed into two groups. The first group consisted of three animals with clinical suspicion of graft dysfunction, in which the ultrasonographic study revealed areas of parenchymal destructuring. In the scintigraphic study, heterogenous uptake was observed; there was no uptake in one animal. Necropsy of these three animals revealed areas of graft necrosis. The second group consisted of five animals with good clinical evolutions, in which the ultrasonographic study showed portal dilation, portal flow with arterial spiculations, and homogenous echogenicity of the hepatic parenchyma. The scintigraphic study revealed homogenous uptake by the graft and an elimination speed of the hepatobiliary agent similar to that of the native liver. CONCLUSIONS: An heterogenous echostructure of the graft provided a sign of poor prognosis indicating necrosis in the same way as heterogenous uptake or nonuptake of radioisotope upon scintigraphy. Scintigraphy is a good method to evaluate biliary function and bile elimination. In an AHLT-PVA, the main ultrasound findings derived from arterialization were dilation of the portal system and portal flow with arterial spiculations.

Animals↗
PubMed2006

Description of endoscopic ventricular anatomy in myelomeningocele.

OBJECTIVE: The purpose of this work is to present our endoscopic neuroanatomical findings of a series of myelomeningocele and hydrocephalus patients, treated with endoscopic third ventricular cisternostomy (ETVC), in order to describe ventricular configuration abnormalities in this group of patients, in which this neurosurgical procedure has limited performance. METHOD: We checked the videos of 10 endoscopic third ventricular cisternostomies of myelomeningocele patients taken during 24 months as from December 1998. A previous guideline is designed to record anatomic variables in the lateral ventricles, IIIrd ventricle, and basal cisterns. The topic is analyzed in view of the necropsy and imaging background data. RESULTS: The ETVC of lateral ventricles showed: absence of septum (9/10); absence of anteroseptal vein (8/10); absence of choroid plexus and thalamostriate vein (0/10); absence of fornix (1/10): small foramen of Monro (4/10). The ETVC of the IIIrd ventricle showed: impossibility of recognizing any mammillary bodies (4/10); presence of septations (5/10); presence of atypical veins in the floor (6/10); translucent floor (5/10); floor umbilications (5/10); absence of infundibulum (4/10); arachnoid adherences (7/10); and visual contact of basilar artery (4/10). CONCLUSION: There are categorical structural alterations in the ventricular system of myelomeningocele patients that are well correlated with previous necropsy and imaging reports. The ventricular system of dysraphic children presents severe anatomic alterations, which alter the reference points of the classical endoscopic third ventricular cisternostomy.

Cisterna Magna↗
PubMed2006

Infectious haemolytic anaemia causes jaundice outbreaks in seawater-cultured coho salmon, Oncorhynchus kisutch (Walbaum), in Chile.

In the last 9 years, epizootics of an icterus condition has affected coho salmon, Oncorhynchus kisutch (Walbaum), reared in seawater cages in southern regions of Chile. At necropsy, fish from field cases exhibited signs of jaundice accompanied by pale light-brown livers and dark spleens. Histopathological and haematological results indicated that these fish presented haemolytic anaemia. After microbiological examination no bacterial or viral agents could be identified as aetiological agents of this disease. In an infectivity trial, coho salmon, Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), were inoculated intraperitoneally with a filtrate of an organ homogenate (0.45 microm) from a diseased coho salmon and held for 60 days in tanks supplied with fresh water. The disease was only reproduced in coho salmon in which mortalities, beginning at day 23 post-inoculation (p.i.), reached a cumulative value of 24% at day 27 p.i. This condition was transmitted to non-inoculated cohabiting coho salmon suggesting that it is a waterborne disease. Thus, this icteric condition is caused by an infectious form of haemolytic anaemia, probably of viral aetiology, and coho salmon are more susceptible than either Atlantic salmon or rainbow trout.

Anemia, Hemolytic↗
PubMed2006

Sensorineural hearing loss in insulin-like growth factor I-null mice: a new model of human deafness.

It has been reported that mutations in the gene encoding human insulin-like growth factor-I (IGF-I) cause syndromic hearing loss. To study the precise role of IGF-I in auditory function and to hypothesize the possible morphological and electrophysiological changes that may occur in the human inner ear, we have analysed the auditory brainstem response in a mouse model of IGF-I deficiency. We show here that homozygous Igf-1(-/-) mice present an all-frequency involved bilateral sensorineural hearing loss. Igf-1(-/-) mice also present a delayed response to acoustic stimuli; this increases along the auditory pathway, indicating a contribution of the central nervous system to the hearing loss in Igf-1(-/-) mice. These results support the use of the Igf-1(-/-) mouse as a new model for the study of human syndromic deafness.

Acoustic Stimulation↗
PubMed2004

Experimental infection of coho salmon Oncorhynchus kisutch by exposure of skin, gills and intestine with Piscirickettsia salmonis.

Piscirickettsiosis pathogenesis was examined using some tissues as entry portals of Piscirickettsia salmonis in coho salmon. Juvenile fish, weighing approximately 8.4 g, were used in this trial. Inocula were prepared using the strain SLGO-95 of P. salmonis. The micro-organism was cultured in the CHSE-214 cell line as described by Fryer et al. (1990) and doses containing 10(4.7) and 10(3.7) TCID50 were prepared. Each dose was used to infect the fish via skin, gills and intestine. Skin and gills were exposed by calibrated drops, and the intestine by an intubation through the anal opening. Some fish were injected intraperitoneally with the same P. salmonis doses, as positive virulence controls. Sham-inoculated fish for each of the tested routes were also included as negative controls. Piscirickettsiosis was experimentally reproduced with all the inoculation methods. Cumulative mortalities and survival analyses showed that the most effective entry portal was skin followed by intestinal intubation and finally by gill infection.

Animals↗
PubMed2004

Development and validation of a reversed-phase liquid chromatographic method for analysis of D4T (Stavudine) in rat plasma.

An improved and simplified high-performance liquid chromatographic (HPLC) method at UV detection 265 nm is presented for the determination of d4T in rat plasma. The mobile phase consists of methanol-distilled water-acetic acid in the 23:77:0.2 (v/v) ratio. Quantification is achieved by the peak-area ratio method with reference to the internal standard. This paper presents linearity, accuracy, precision, limit of quantification and limit of detection, specificity-selectivity and sample stability data. Based on the intra and inter-day validation, all coefficients of variation (CV) were found less than 15%. The assay is sufficiently rapid and sensitive and was applied in a pharmacokinetic study in rats.

Animals↗
PubMed2003

Experimental vertical transmission of Piscirickettsia salmonis and in vitro study of attachment and mode of entrance into the fish ovum.

Piscirickettsia salmonis is a pathogenic bacterial agent causing septicaemic disease in salmon. Since its isolation in Chile in 1989, P. salmonis has continually produced high mortality rates in salmon farms. Little information exists regarding the mechanisms of vertical transmission of this pathogen. Experimental vertical transmission was established in the present study by inoculation of male and female rainbow trout broodstock with P. salmonis. The bacterium was subsequently detected using indirect immunofluorescence in milt and coelomic fluid of the majority of inoculated broodstock (14/15). Bacteria were detected in the fry when 1 or both parents were inoculated, although none of the infected fry presented signs of the disease. P. salmonis was also detected in progeny obtained through fertilisation ova from non-inoculated females incubated in a medium containing a bacterial suspension, demonstrating transmission during the process of fertilisation. Ova infected in vitro were examined at sample periods from 30 s to 60 min using scanning electron microscopy. This demonstrated that the bacterium attaches to the ova by means of membrane extensions, structures which we have called 'piscirickettsial attachment complex' (PAC) and which would allow later penetration into the ovum.

Animals↗
PubMed2001

Delayed inner ear maturation and neuronal loss in postnatal Igf-1-deficient mice.

Insulin-like growth factor-1 (IGF-1) has been shown to play a key role during embryonic and postnatal development of the CNS, but its effect on a sensory organ has not been studied in vivo. Therefore, we examined cochlear growth, differentiation, and maturation in Igf-1 gene knock-out mice at postnatal days 5 (P5), P8, and P20 by using stereological methods and immunohistochemistry. Mutant mice showed reduction in size of the cochlea and cochlear ganglion. An immature tectorial membrane and a significant decrease in the number and size of auditory neurons were also evident at P20. IGF-1-deficient cochlear neurons showed increased caspase-3-mediated apoptosis, along with aberrant expression of the early neural markers nestin and Islet 1/2. Cochlear ganglion and fibers innervating the sensory cells of the organ of Corti presented decreased levels of neurofilament and myelin P(0) in P20 mouse mutants. In addition, an abnormal synaptophysin expression in the somata of cochlear ganglion neurons and sensory hair cells suggested the persistence of an immature pattern of synapses distribution in the organ of Corti of these animals. These results demonstrate that lack of IGF-1 in mice severely affects postnatal survival, differentiation, and maturation of the cochlear ganglion cells and causes abnormal innervation of the sensory cells in the organ of Corti.

Aging↗
PubMed2001

Effect of sildenafil on non-adrenergic non-cholinergic neurotransmission in bovine penile small arteries.

The purpose of the present study was to investigate the effect of the phosphodiesterase isoenzyme V inhibitor, sildenafil, on non-adrenergic non-cholinergic neurogenic relaxations of intracavernous isolated penile small arteries. Dense plexes of nerve fibres immunoreactive for neural nitric oxide (NO) synthase were observed in the adventitia-media junction of the penile small arteries. In 5-hydroxytryptamine-contracted preparations, the inhibitor of NO synthase, N(G)-nitro-L-arginine (L-NOARG), and of soluble guanylyl cyclase, 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ), reduced the electrical field stimulation-induced relaxations. Sildenafil and exogenous NO induced relaxations of penile small arteries. Sildenafil enhanced NO and vasoactive intestinal peptide-induced relaxations. Moreover, sildenafil increased the duration of the relaxations elicited by electrical field stimulation in penile small arteries and corpus cavernosum tissue. In the presence of L-NOARG, sildenafil only at supratherapeutic concentrations reduced the prazosin-sensitive contractions elicited by EFS in penile small arteries. Neurogenic NO-mediated and guanylyl cyclase-dependent relaxations of penile small arteries and corpus cavernosum tissue, considered to be associated with the vasodilatation leading to erection, are selectively enhanced by an inhibitor of phosphodiesterase V.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2001

[Prognostic factors in colorectal neoplasm. Multivariate analysis in 224 patients].

BACKGROUND: Staging of colorectal carcinoma has prognostic value and allows to take decisions about adjuvant therapy and follow up. Prognostic factors are not universally accepted and there are different staging classifications. AIM: To assess the prognostic value of clinical and pathological variables in 224 patients subjected to a curative resection of a colorectal carcinoma. PATIENTS AND METHODS: A retrospective analysis of 99 men and 125 women, aged 23 to 91 years old subjected to a curative resection of a colorectal carcinoma and followed up for a mean of 72 months. RESULTS: Global survival at 60 months was 72%. Univariate analysis showed that tumor localization, vascular permeation, wall infiltration and number of involved lymph nodes had an influence on survival. A Cox regression model disclosed tumor localization (colon versus rectum), a carcino-embryonic antigen over 30 ng/ml, vascular permeation, presence of 1 to 4 involved lymph nodes, or 5 or more lymph nodes and the presence of an apical lymph node as variables with significant prognostic value. CONCLUSIONS: Our series confirms the prognostic importance of lymph node involvement. This parameter is incorporated in Jass, GITSG (both modifications of Dukes classIfication) and TNM staging scores.

Adenocarcinoma↗
PubMed2001

[Usefulness of the statistical bulletin of deaths to identify extrahospital deaths in the context of a myocardial infarction population registry].

INTRODUCTION AND AIMS: This paper aimed to study the usefulness of the Statistical Bulletin of Deaths (SBD) for identifying extrahospital deaths due to acute coronary ischaemia, and to determine the most efficient strategy in the selection of death causes that appear in the SBD, which are the most efficient for the identification. METHODS: Those extrahospital deaths, which, among the causes of death, recorded a diagnostic code indicating that they might have been caused by coronary ischaemia, were included. To study the usefulness of the death certificate we calculated the sensitivity and the positive predictive value of cardiac ischaemia. To determine the most efficient strategy for selecting causes of death we compared two selection strategies: the first, using only the basic cause of death; and the second using all the causes appearing in the SBD. RESULTS: Of the 395 SBD selected, 161 were classed as acute heart attacks. In those SBD in which cardiac ischaemic disease was given as the basic cause of death, we obtained a sensitivity of 82.6% (CI 95%: 75.9-88.1) and a positive predictive value of 72.7% (CI 95%: 65.6-79). The most efficient strategy in SBD selection proved to be the investigation of death certificates in which cardiac ischaemia appeared as one of all the causes of death, and death certificates in which the basic cause of death was coded as diabetes mellitus, essential arterial hypertension, hypertensive heart disease, cardiac dysrhythmia, and cardiac insufficiency. CONCLUSIONS: The information provided by death certificates for extrahospital deaths due to coronary ischaemia is reliable. A sensitive and efficient SBD selection strategy is proposed for the detection of cases.

Adult↗
PubMed2000

The safety and efficacy of a two-dose daclizumab (zenapax) induction therapy in liver transplant recipients.

BACKGROUND: Induction therapy with daclizumab has been shown to be efficacious in the prevention of acute rejection in kidney transplant patients. The routine use of antibody induction therapy in liver transplantation has not gained widespread acceptance, except in the cases of renal insufficiency. The recent approval of daclizumab prompted us to initiate this pilot study using induction therapy in those patients at risk for developing posttransplant renal insufficiency. METHODS: This nonrandomized study examined the use of daclizumab in 39 of the last 97 liver transplants performed at the University of Alabama in Birmingham. The daclizumab group received 2 mg/kg intravenously before organ engraftment, and 38 of the 39 received 1 mg/kg intravenously on postoperative day 5. The control group consisted of the remaining 58 contemporary patients. Additional immunosuppression consisted of steroids, tacrolimus, or microemulsion cyclosporine in all patients and mycophenolate mofetil in selected patients. RESULTS: Pretransplant demographics were not significantly different between the groups. In the induction group there were significantly fewer males, 14 (36%) vs. 34 (59%) (P=0.03). They had greater renal insufficiency at the time of transplant, serum creatine 1.9+/-0.37 mg/dl vs. 0.8+/-0.5; P=0.0009, and more patients were at higher acuity (status 1 and 2A): 12 (31%) vs. 3 (5%) P=0.0006 than in the noninduction group. By postoperative day 7, renal function improved in the induction group such that it was not significantly different from the noninduction group and remained similar throughout the rest of the follow-up. The induction group also experienced significantly less acute rejection, 7 (18%) vs. 23 (40%) (P=0.02) than in the noninduction group in the first 6 months. The 1-, 3-, and 6-month patient survival rates were similar in the induction group, 97.4%, 97.4%, and 97.4%, vs. non-induction 94.8%, 93.0%, and 93% (P=NS). The incidence of cytomegalovirus, in the first 6 months, in the induction group was four (10%) vs. five (9%) (P=NS) in the noninduction group. CONCLUSION: In the pilot study, induction therapy with daclizumab was safe, facilitated improvement in renal function, and appeared to reduce the incidence of acute rejection. Combination therapy with daclizumab may be an important adjunct in immunosuppressive strategies for liver transplant recipients.

Adult↗
PubMed2000

Hypersensitivity of malignant hyperthermia-susceptible swine skeletal muscle to caffeine is mediated by high resting myoplasmic [Ca2+ ].

BACKGROUND: Malignant hyperthermia (MH) is an inherited pharmacogenetic syndrome that is triggered by halogenated anesthetics and/or depolarizing muscle relaxants. MH-susceptible (MHS) skeletal muscle has been shown to be more sensitive to caffeine-induced contracture than muscle from nonsusceptible (MHN) subjects and is the basis for the most commonly used clinical diagnostic test to determine MH susceptibility. METHODS: We studied the effects of caffeine on myoplasmic free calcium concentration ([Ca2+]i) in MHN and MHS swine muscle fibers by means of Ca2+-selective microelectrodes before and after K+-induced partial depolarization. RESULTS: [Ca2+]i in untreated MHN fibers was 123 +/- 8 nm versus 342 +/- 33 nm in MHS fibers. Caffeine (2 mm) caused an increase in [Ca2+]i in both groups (296 +/- 41 nm MHN vs. 1,159 +/- 235 nm MHS) with no change in resting membrane potential. When either MHN or MHS, muscle fibers were incubated in 10 mm K+ [Ca2+]i transiently increased to 272 +/- 22 nm in MHN and 967 +/- 38 nm in MHS for 6-8 min. Exposure of MHN fibers to 2 mm caffeine while resting [Ca2+]i was elevated induced an increment in [Ca2+]i to 940 +/- 37 nm. After 6-8 min of exposure to 10 mm K+, [Ca2+]i returned to control levels in all fibers, and the effect of 2 mm caffeine on resting [Ca2+]i returned to control, despite continued partial membrane depolarization. CONCLUSIONS: These results suggest that the increased "sensitivity" to caffeine of MHS swine muscle fibers is a nonspecific response related, at least in part, to the high resting [Ca2+]i and not an increased caffeine sensitivity of the sarcoplasmic reticulum Ca2+ release channel per se.

Animals↗
PubMed2000

Tachykininergic excitatory neurotransmission in the pig intravesical ureter.

PURPOSE: The present investigation was designed to study the role played by neurokinin A (NKA) in the non adrenergic non cholinergic (NANC) neurotransmission of the pig intravesical ureter. MATERIALS AND METHODS: We used immunohistochemical techniques to evidence the distribution of NKA-immunoreactive (NKA-IR) fibers in the pig intravesical ureter. We have also performed isolated organ bath experiments to release endogenous tachykinins from ureteral nerves and to characterize the functionally active receptor through which endogenous ligands evoke contraction, and to show the effect of exogenous tachykinins on intravesical ureteral smooth muscle. RESULTS: NKA-IR fibers were found penetrating through ureteral adventitia and distributed in the subepithelial and muscular layers. NKA-IR fibers were not found around small arteries supplying the ureter or in the associated intramural ganglia. Electrical field stimulation (EFS, 1 ms duration, 2 to 16 Hz, 20 s trains) performed in NANC conditions evoked frequency-dependent contractions which were reduced by capsaicin (10-5 M) and GR 94800 (3 x 10-8 M), sensory neurotoxin and NK2 receptor antagonist, respectively. Contractions to EFS were abolished by tetrodotoxin (10-6 M). Exogenous NKA and substance P (SP) induced dose-dependent contractions, characterized by an increase of the ureteral basal tone, NKA being more potent than SP. CONCLUSIONS: These results suggest that tachykinins, especially NKA, released from capsaicin-sensitive primary afferents, are involved in the NANC excitatory neurotransmission, contracting the smooth muscle via NK2 receptors activation, in the pig intravesical ureter. NKA at this level does not seem to participate in the regulation of local blood flow, plasmatic extravasation or ganglionar transmission.

Animals↗
PubMed1999

Routes of entry of Piscirickettsia salmonis in rainbow trout Oncorhynchus mykiss.

Since 1989, Piscirickettsia salmonis, the causal agent of piscirickettsiosis, has killed millions of farmed salmonids each year in southern Chile. The portal of entry for the pathogen was investigated by use of selected experimental infections in juvenile rainbow trout (12 g). The methods used were intraperitoneal injection, subcutaneous injection, patch contact on skin, patch contact on gills, intestinal intubation and gastric intubation. Cumulative mortalities at Day 33 post-inoculation were 98, 100, 52, 24, 24, and 2%, respectively. It was shown that intact skin and gills could be penetrated by P. salmonis. The high mortality obtained in subcutaneously injected fish indicated that skin injuries could facilitate the invasion of this pathogen. Results suggested that the main entry sites are through the skin and gills and that the oral route may not be the normal method by which P. salmonis initiates infection of salmonids.

Administration, Topical↗
PubMed1999

Chemical composition, digestibility and antinutritional factors content of two wild legumes: Styphonolobium burseroides and Acacia bilimekii.

The chemical composition, digestibility and toxin contents of two wild legumes: Styphnolobium burseroides and Acacia bilimekii, collected in a semi-arid zone of Mexico, were determined. Both legumes had a high fiber content. The seeds of Styphnolobium burseroides had a low protein content (14%), and the pod a high content of reducing sugars. However the seeds of Acacia bilimekii had a high protein concentration (35%). The seed proteins were low in sulphur amino acids and tryptophan in both legumes but were rich in lysine. Trypsin inhibitors and lectins were present in low concentrations; alkaloids and cyanogenic glucosides were not detected. The in vitro digestibility for monogastric animals was low but the same test with ruminal juice showed a high digestibility for both legumes. Based on their chemical composition and digestibility, these legumes could be a good alternative source in the feeding of ruminants.

Amino Acids↗