PubMed Health⌕ Search

Biomedical subjects

C Arroyo

Publications and source records attributed to C Arroyo.

At least 19 recordsLinked to original sources
PubMed2006

Observation of muon neutrino disappearance with the MINOS detectors in the NuMI neutrino beam.

This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current nu(mu) interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27 x 10(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336+/-14 events. The data are consistent with nu(mu) disappearance via oscillations with |Delta(m)2/32|=2.74 +0.44/-0.26 x10(-3)eV(2) and sin(2)(2theta(23))>0.87 (68% C.L.).

Journal Article↗
PubMed2006

[Use of a virtual immersion computer simulator as a model for basic training in laparoscopic urology].

BACKGROUND: to date, it has not been defined the best method for teaching urologic laparoscopy, however it is well recognized that it involves a steep learning curve. METHODS: A course of Laparoscopic Urology was done in our Institute. The program included skill practices in a virtual immersion simulator which evaluated, the score and time to complete each activity. This was done in a group of residents with previous experience with this virtual simulator (group 1) and another group of residents with no experience (group 2). Four different basic tasks were performed in the virtual simulator, which included: coordination, cutting, clip application and performing a simple suture. RESULTS: When we compared the scores between both groups the mean scores for each task were superior in group 1 compared to the group 2, with no statistically significant difference, however when we compared the time to complete each task, it was shorter in group 1 compared to group 2 with a statistically significant difference. CONCLUSIONS: The performance of residents without experience in a virtual simulator was similar to that of previously trained residents, however it takes less time to complete each task as the resident gains experience in these simulators. The use of virtual simulators for laparoscopy training are useful when learning basic techniques allowing the surgeon to improve hand dexterity and coordination in laparoscopic surgery.

Computer Simulation↗
PubMed2005

Precision measurement of the weak mixing angle in Møller scattering.

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.

Journal Article↗
PubMed2004

Observation of parity nonconservation in møller scattering.

We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV)=[-175+/-30(stat)+/-20(syst)] x 10(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron's weak charge at low energy Q(e)(W)=-0.053+/-0.011. This is consistent with the standard model expectation at the current level of precision: sin((2)theta(W)(M(Z))((-)MS)=0.2293+/-0.0024(stat)+/-0.0016(syst)+/-0.0006(theory).

Journal Article↗
PubMed2001

Weekly trastuzumab and paclitaxel therapy for metastatic breast cancer with analysis of efficacy by HER2 immunophenotype and gene amplification.

PURPOSE: This phase II study evaluated weekly trastuzumab and paclitaxel therapy in women with HER2-normal and HER2-overexpressing metastatic breast cancer. Efficacy was correlated with immunohistochemical and fluorescent in situ hybridization (FISH) assay results. PATIENTS AND METHODS: Eligible patients had bidimensionally measurable metastatic breast cancer. Up to three prior chemotherapy regimens, including prior anthracycline and taxane therapy, were allowed. Trastuzumab 4 mg/kg and paclitaxel 90 mg/m2 were administered on week 1, with trastuzumab 2 mg/kg and paclitaxel 90 mg/m2 administered on subsequent weeks. HER2 status was evaluated using four different immunohistochemical assays and FISH. RESULTS: Patients received a median of 25 weekly infusions (range, one to 85 infusions). Median delivered paclitaxel dose-intensity was 82 mg/m2/wk (range, 52 to 90 mg/m2/wk). The intent-to-treat response rate for all 95 patients enrolled was 56.8% (95% confidence interval, 47% to 67%). A response rate of 61.4% (4.5% complete response, 56.8% partial response) was observed in 88 fully assessable patients. In patients with HER2-overexpressing tumors, overall response rates ranged from 67% to 81% compared with 41% to 46% in patients with HER2-normal expression (ranges reflect the different assay methods used to assess HER2 status). Differences in response rates between patients with HER2-overexpressing tumors and those with normal HER2 expression were statistically significant for all assay methods, with CB11 and TAB250 antibodies and FISH having the strongest significance. Therapy was generally well tolerated, although three patients had serious cardiac complications. CONCLUSION: Weekly trastuzumab and paclitaxel therapy is active in women with metastatic breast cancer. Therapy was relatively well tolerated; however, attention to cardiac function is necessary.

Adult↗
PubMed2001

[Infection of ascending aortic graft: treatment with surgical cleaning, graft preservation and transposition of muscle flaps. Report of two cases].

Mediastinitis with graft infection is a serious complication of ascending aorta replacement. We report two cases of graft infection, treated with surgical cleaning, graft preservation and transposition of muscle flaps. A 62 years old male was admitted 34 days after an ascending aortic grafting due to a sternal dehiscence and mediastinitis. Antimicrobial treatment was started and a surgical cleaning performed, leaving an open sternotomy. Three days later, the thoracic cavity was closed with a rectus abdominis muscle flap. After 23 months of follow up, the patient is well and without evidence of infection. A 74 years old male was subjected to an aortic valve and ascending aorta replacement and a myocardial revascularization. In the postoperative period, the patient developed septic signs, and a purulent drainage. A CAT scan showed a liquid collection surrounding the aortic graft. On tW Sixteenth postoperative day, a surgical cleaning was performed and the thorax was closed with the pectoralis major muscle. After 10 months of follow up, the patient is in Good condition and without evidence of infection.

Aged↗
PubMed2000

Improved branching ratio measurement for the decay K(0)(L) --> &mgr;(+)&mgr;(-)

We report results from Experiment 871, performed at the BNL AGS, of a measurement of the branching ratio K(0)(L)-->&mgr;(+)&mgr;(-) with respect to the CP-violating mode K(0)(L)-->pi(+)pi(-). This experiment detected over 6200 candidate &mgr;(+)&mgr;(-) events, a factor of 6 more than that seen in all previous measurements combined. The resulting branching ratio gamma(K(0)(L)-->&mgr;(+)&mgr;(-))/gamma(K(0)(L)-->pi(+)pi(-)) = (3. 474+/-0.057)x10(-6) leads to a branching fraction B(K(0)(L)-->&mgr;(+)&mgr;(-)) = (7.18+/-0.17)x10(-9), which is consistent with the current world average, and reduces the uncertainty in this decay mode by a factor of 3.

Journal Article↗
PubMed2000

Role of mast cells in the pathogenesis of postburn inflammatory response: reactive oxygen species as mast cell stimulators.

Thermal trauma has a direct effect on mast cells, triggering the secretion of histamine. This secretion leads to an enhanced xanthine oxidase activity and an increased production of reactive oxygen species (ROS), the latter being produced after burns through differing mechanisms. As ROS have been shown to have deleterious effects on cellular membranes, a lesion of the mast cell membrane could close the circle of autoinjury due to the vasoactive actions of mast cell mediators. Our studies were designed to assess the potentiality of ROS as stimulators of mast cell degranulation after burns by comparing two groups of rats treated, respectively, with SOD and saline solution after a scald injury. Plasma levels of tryptase and histamine were analyzed as markers of mast cell activity. A comparison of the mean increases of tryptase between baseline and 3-h postburn levels in the two groups shows significant differences (p < 0.001) (control: 0.13+/-0.04, SOD: 0.03+/-0.01). When comparing the mean increases between the baseline and 3 h postburn levels of histamine in the two groups, significant differences were also found (p < 0.001) (control group: 2.70+/-0.57. SOD group: 1.22+/-0.32). The lower levels of histamine and tryptase induced by SOD provides indirect evidence that ROS are involved in the process, causing the release of such mediators by mast cells, which may in turn suggest that ROS can act as stimulators of mast cell degranulation in burns.

Animals↗
PubMed1999

[Popliteal vein aneurysm].

The popliteal vein aneurysm is a rare condition that can lead to local symptoms, thrombosis and pulmonary embolism. We report the case of a 67 years old, otherwise healthy white male, who presented to us with localised swelling and pain in the left popliteal fossa. Duplex ultrasound and venography were obtained, confirming the diagnosis of popliteal vein aneurysm. The patient underwent tangential aneurysmectomy and lateral venorrhaphy, recovery was uneventful remaining asymptomatic. The reconstruction was demonstrated patent on a duplex scan. The popliteal vein aneurysm is a potentially fatal condition for which surgical treatment is recommended.

Aged↗
PubMed1998

High-performance liquid chromatography analysis of Bobel-24 in biological samples for pharmacokinetic, metabolic and tissue distribution studies.

A rapid and simple HPLC method is described for the determination of Bobel-24 (2,4,6-triiodophenol) and other iodinated derivatives in biological samples. The sample preparation was liquid-liquid extraction before injection onto the HPLC system. 2,6-Diiodo-4-methylphenol was used as internal standard. Separation was obtained using a reversed-phase column under isocratic conditions. The mobile phase consisted of water-acetonitrile (62:38). 2,4,6-Triiodophenol was detected at 277 nm. This method was used for Bobel-24 determination in plasma, urine, synovial liquid and different tissues. The assay was applied to pharmacokinetic studies in dog and horse plasma and different dog tissues for tissue distribution profiles toxicological and metabolic studies. In addition, this method for biological samples can be applied to non-biological samples such as pharmaceutical formulations in stability studies and quality control assays.

Animals↗
PubMed1997

Simple and robust high-performance liquid chromatographic method for the determination of ranitidine in microvolumes of human serum.

A simple robust high-performance liquid chromatographic method is described for the determination of ranitidine in microvolumes of human serum. The drug of interest was isolated using liquid-liquid extraction with dichloromethane and back-extraction with 0.1% phosphoric acid and separation was obtained using a reversed-phase column under isocratic conditions, with ultraviolet detection at 313 nm. Intra-day and inter-day coefficients of variation ranged from 1 to 6% and 3 to 10%, respectively. Accuracy of the assay was less than 10% at all concentrations. The limit of detection and the limit of quantitation were 2 and 7 ng/ml, respectively. The linearity was assessed in the range 10-1000 ng/ml. It was shown that a group of common drugs co-administered with ranitidine did not interfere with its determination. The applicability of this method for the pharmacokinetic study of ranitidine following i.v. infusion in patients was demonstrated using only 100 microl of serum. The ruggedness of the assay was demonstrated over a three-year period.

Anti-Ulcer Agents↗
PubMed1997

Determination of imipenem in plasma by high-performance liquid chromatography for pharmacokinetic studies in patients.

A rapid and simple HPLC method is described for the determination of imipenem in human plasma. After blood collection, plasma was separated by centrifugation and immediately stabilized with 3-morpholinopropanesulfonic acid (MOPS) and ethylene glycol solution (1:1). The sample preparation, before injection into HPLC, was ultrafiltration. The mobile phase was boric acid buffer. The imipenem was detected at 300 nm and cilastatin sodium, coadministered, did not interfere. Calibration curves in human plasma were linear from 0.1 to 100 microg/ml. The limit of detection was 0.030 microg/ml. Inter-day precision at 0.1 microg/ml, determined as the coefficient of variation, was 6.26%. Only 250 microl of plasma was required in our assay. Due to the limited stability of imipenem [G.B. Smith et al., J. Pharm. Sci., 79 (1990) 732], stability studies in plasma were done to establish appropriate storage conditions. The assay was applied to pharmacokinetic studies in patients.

Chromatography, High Pressure Liquid↗
PubMed1997

Determination of captopril in plasma by high-performance liquid chromatography for pharmacokinetic studies.

A high-performance liquid chromatographic method is described for the determination of free captopril in human plasma N-Acetyl-L-cysteine (NAC) was used as an internal standard. Plasma samples were immediately derivatized with N-(1-pyrenyl)maleimide (NPM) and stabilized with 11 M HCl. The drug of interest was isolated using a liquid-liquid extraction with ethyl acetate and separation was obtained using a reversed-phase column under isocratic conditions with fluorescence detection. The sample volume was 150 microliters plasma. The intra- and inter-day accuracy and precision, determined as relative error and coefficient of variation respectively, were less than 10%. The lower limit of quantitation, based on standards with acceptable coefficients of variation, was 25 ng/ml. No endogenous compounds were found to interfere. The linearity was assessed in the range of 25-600 ng/ml. This method has been demonstrated to be suitable for pharmacokinetic studies in humans.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Melanocyte reservoir in vitiligo.

BACKGROUND: Dopa-negative, inactive melanocytes, present in the middle portion of the hair follicle, but also in hair bulbs, have been reported as a source of pigment cells, when repopulation of epidermal melanocytes occurs. A melanocyte reservoir in these anatomical sites has been suggested. Our objective was to investigate the ability of the lower third of the hair follicle (hair bulb) to repigment achromic skin in vitiligo. METHODS: Scalp hair bulbs were transplanted within leukodermic areas in 10 patients with vitiligo. RESULTS: Repigmentation around the grafts was suitable for evaluation in four cases. Dopa-positive (+) cells were seen in the epidermal basal cell layer of the repigmented areas. CONCLUSIONS: Although these findings were observed only in a few patients, they suggest that melanocytes from the implanted lower third portion of the hair follicle (hair bulb) act as a reservoir in this anatomic location and are able to migrate and repigment achromic areas in vitiligo.

Adult↗
PubMed1994

The pathology of low-grade adenosquamous carcinoma of the breast. An immunohistochemical study.

Low-grade adenosquamous carcinoma of the breast is a variant of metaplastic mammary carcinoma characterized by a locally invasive growth pattern and a low risk for metastases. In this study none of the carcinomas exhibited greater than 5 percent nuclear immunoreactivity for estrogen or progesterone receptors, and as a result they were classified as negative for these receptors. Reactivity for cathepsin D was found in 39 percent of the tumors, largely limited to areas of epidermoid differentiation. Membrane immunoreactivity for HER-2/neu oncogenes was present in glandular components of 46 percent of the carcinomas. Immunoreactivity for p53 (greater than 10 percent of nuclei) was present in 13 percent of the tumors, also in glandular elements. Six different patterns of coexpression of p53, HER-2/neu and cathepsin D were found, the most frequent being the following: HER-2/neu(+), p53(-), cathepsin D(-) (9 cases, 39%); cathepsin D(+), p53(-), HER-2/neu(-) (5 cases, 22%); and the three markers negative (5 cases, 22 percent). Coexpression of the two oncogenes was found in only one tumor which was also positive for cathepsin D. These results indicate that the expression of various immunohistochemical prognostic markers may be heterogeneous and that there may not be a specific pattern of marker coexpression within a carefully defined histologic subtype of mammary carcinoma. Furthermore, characteristics reported to be associated with an unfavorable prognosis (negative hormone receptors, presence of cathepsin D, and expression of oncogenes such as HER-2/neu) may be found in a substantial proportion of tumors that comprise this clinically and histologically low-grade variant of mammary carcinoma. This disassociation between expected prognosis based on expression of current prognostic markers and observed prognosis occurs in other forms of mammary carcinoma. Medullary carcinoma, when diagnosed on the basis of rigorously defined criteria, has an excellent prognosis despite the fact that these tumors are characterized by absence of estrogen and progesterone receptors and a high proliferative rate. The histological classification of mammary carcinomas is itself an important prognostic variable that may take precedence over selected biochemical markers.

Adult↗