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Biomedical subjects

R Garcia

Publications and source records attributed to R Garcia.

At least 55 records · Page 3Linked to original sources
PubMed2001

Regulation of Drosophila TRPL channels by immunophilin FKBP59.

Transient receptor potential and transient receptor potential-like (TRPL) are Ca(2+)-permeable cation channels found in Drosophila photoreceptor cells associated with large multimeric signaling complexes held together by the scaffolding protein, INAD. To identify novel proteins involved in channel regulation, Drosophila INAD was used as bait in a yeast two-hybrid screen of a Drosophila head cDNA library. Sequence analysis of one identified clone showed it to be identical to the Drosophila homolog of human FK506-binding protein, FKBP52 (previously known as FKBP59). To determine the function of dFKBP59, TRPL channels and dFKBP59 were co-expressed in Sf9 cells. Expression of dFKBP59 produced an inhibition of Ca(2+) influx via TRPL in fura-2 assays. Likewise, purified recombinant dFKBP59 produced a graded inhibition of TRPL single channel activity in excised inside-out patches when added to the cytoplasmic membrane surface. Immunoprecipitations from Sf9 cell lysates using recombinant tagged dFKBP59 and TRPL showed that these proteins directly interact with each other and with INAD. Addition of FK506 prior to immunoprecipitation resulted in a temperature-dependent dissociation of dFKBP59 and TRPL. Immunoprecipitations from Drosophila S2 cells and from fly head lysates demonstrated that dFKBP59, but not dFKBP12, interacts with TRPL in vivo. Likewise, INAD immunoprecipitates with dFKBP59 from S2 cell and head lysates. Immunocytochemical evaluation of thin sections of fly heads revealed specific FKBP immunoreactivity associated with the eye. Site-directed mutagenesis showed that mutations of P702Q or P709Q in the highly conserved TRPL sequence (701)LPPPFNVLP(709) eliminated interaction of the TRPL with dFKBP59. These results provide strong support for the hypothesis that immunophilin dFKBP59 is part of the TRPL-INAD signaling complex and plays an important role in modulation of channel activity via interaction with conserved leucyl-prolyl dipeptides located near the cytoplasmic mouth of the channel.

Amino Acid Motifs↗
PubMed2001

Cooperative regulation of Mcl-1 by Janus kinase/stat and phosphatidylinositol 3-kinase contribute to granulocyte-macrophage colony-stimulating factor-delayed apoptosis in human neutrophils.

Polymorphonuclear neutrophils (PMN) are phagocytic cells constitutively programmed for apoptotic cell death. Exposure to GM-CSF delays apoptosis as measured by annexin-V staining and cell morphological change. We found that STAT5B, STAT1, and STAT3 DNA-binding activity was induced by GM-CSF. We also detected activation of the phosphatidylinositol 3-kinase (PI 3-kinase) pathway after GM-CSF treatment which was inhibited by treatment with the PI 3-kinase inhibitors, wortmannin and LY294002. We investigated whether STAT or PI 3-kinase activity was necessary for the pro-survival response of GM-CSF in PMN. Exposure of PMN to GM-CSF in the presence of either AG-490, antisense STAT3 oligonucleotides, or wortmannin resulted in a partial inhibition of GM-CSF-mediated pro-survival activity. GM-CSF induced a time-dependent increase in the mRNA and protein expression of the anti-apoptotic Bcl-2-family protein, Mcl-1. We examined the hypothesis that Janus kinase/STAT and PI 3-kinase regulation of Mcl-1 contributed to GM-CSF-delayed apoptosis. Using either AG-490 or wortmannin alone, we observed a dose-dependent inhibition of GM-CSF-induced Mcl-1 expression. Using suboptimal doses of AG-490 and wortmannin, we found that both drugs together had an additive effect on delayed apoptosis and Mcl-1 expression. These data suggest that cooperative regulation of Mcl-1 by the Janus kinase/STAT and PI 3-kinase pathways contribute to GM-CSF-delayed apoptosis.

Apoptosis↗
PubMed2001

Stress, hippocampal plasticity, and spatial learning.

During the last two decades numerous studies have been conducted in an attempt to correlate the mechanisms of long-term potentiation (LTP) of hippocampal synaptic transmission with those required for spatial memory formation in the hippocampus. Because stressful events block the induction of hippocampal LTP, it has been suggested that deficits in spatial learning following stress may be related to suppression of LTP-like phenomena in the hippocampus. Here I review these studies and discuss them in light of the emerging view that stress may induce changes in thresholds for synaptic plasticity necessary for both LTP induction and spatial memory formation. This phenomenon, known as metaplasticity, may involve a glucocorticoid modulation of calcium homeostasis.

Animals↗
PubMed2001

Constitutive activation of Stat3 by the Src and JAK tyrosine kinases participates in growth regulation of human breast carcinoma cells.

Constitutive activation of signal transducer and activator of transcription (STAT) proteins has been detected in a wide variety of human primary tumor specimens and tumor cell lines including blood malignancies, head and neck cancer, and breast cancer. We have previously demonstrated a high frequency of Stat3 DNA-binding activity that is constitutively-induced by an unknown mechanism in human breast cancer cell lines possessing elevated EGF receptor (EGF-R) and c-Src kinase activities. Using tyrosine kinase selective inhibitors, we show here that Src and JAK family tyrosine kinases cooperate to mediate constitutive Stat3 activation in the absence of EGF stimulation in model human breast cancer cell lines. Inhibition of Src or JAKs results in dose-dependent suppression of Stat3 DNA-binding activity, which is accompanied by growth inhibition and induction of programmed cell death. In addition, transfection of a dominant-negative form of Stat3 leads to growth inhibition involving apoptosis of breast cancer cells. These results indicate that the biological effects of the Src and JAK tyrosine kinase inhibitors are at least partially mediated by blocking Stat3 signaling. While EGF-R kinase activity is not required for constitutive Stat3 activation in breast cancer cells, EGF stimulation further increases STAT DNA-binding activity, consistent with an important role for EGF-R in STAT signaling and malignant progression. Analysis of primary breast tumor specimens from patients with advanced disease revealed that the majority exhibit elevated STAT DNA-binding activity compared to adjacent non-tumor tissues. Our findings, taken together, suggest that tyrosine kinases transduce signals through Stat3 protein that contribute to the growth and survival of human breast cancer cells in culture and potentially in vivo.

Animals↗
PubMed2001

Application of experimental design in a method for screening sediments for global determination of organic tin by electrothermal atomic absorption spectrometry (ETAAS).

An experimental design was developed to obtain a simple procedure for global determination of organic tin compounds in sediment. Sediment was extracted by a two-phase method and tin was determined in the organic extract by electrothermal atomic absorption spectrometry (ETAAS), with palladium as chemical modifier. A Plackett-Burman design for screening and a fractional central composite design (CCD) for optimizing were used for evaluation of the effects of several variables. The results showed that sediment mass, volume and concentration of extracting acid, pyrolysis and atomization temperatures, and modifier concentration affect the determination. Reference material PACS-2 was analyzed to evaluate the procedure. It was possible to extract 82% of the organotin content certified in the reference sediment. The limit of detection (LOD) was 0.08 microg g(-1) and the relative standard deviation was 4%. The method was applied to the analysis of estuarine superficial sediments from Gipuzkoa (Spain). The organotin content of these samples ranged from 0.7 to 7.7 microg g(-1), as tin, on a dry-weight basis.

Acetic Acid↗
PubMed2001

IL-5 priming of the PMA-induced oxidative metabolism of human eosinophils from allergic and normal subjects during a pollen season.

AIM: To study the effect of IL-5 priming on the PMA-induced oxidative metabolism of blood eosinophils from allergic patients and healthy controls, during pollen exposure. METHODS: Twenty birch pollen allergic patients with seasonal symptoms of rhinitis or rhinitis plus asthma were studied during the birch pollen season of Sweden. Eosinophils were purified to > 95% by Percoll gradients followed by the MACS system. Oxidative metabolism was measured by a lucigenin enhanced chemiluminescence (CL) assay. Eosinophils were primed with IL-5 and subsequently stimulated with PMA. The signal transduction mechanisms of IL-5 priming were studied using the MEK inhibitor PD 98059, the PkC inhibitors Staurosporine, Ro 318220, Gö 6983 and the PI3kinase inhibitor Wortmannin. RESULTS: During the season, the eosinophils from the allergic patients showed a reduced t(1/2)rise compared to the non-allergic controls (P = 0.019) after stimulation. IL-5 reduced the total PMA CL response both in control and patients' cells (P = 0.012 and 0.0054 resp.), whereas it primed it in terms of the t(1/2)rise of the curves, in both groups (P = 0.012 and 0.0015 resp.). The PMA-induced CL reactions were inhibited by PD 98059, all PkC-inhibitors and Wortmannin. IL-5 priming counteracted only the MEK inhibition significantly. CONCLUSIONS: Blood eosinophils from allergic patients are primed in vivo, as compared to eosinophils from non-allergic controls, during a pollen season. Interleukin-5 primes equally the PMA-induced oxidative metabolism of human eosinophils from healthy or allergic subjects. The mechanism of IL-5 priming after PMA stimulation of oxygen radical production is MEK independent.

Carrier Proteins↗
PubMed2001

Orthotopic liver transplantation for alcoholic liver disease: a retrospective analysis of survival, recidivism, and risk factors predisposing to recidivism.

The aim of this study performed at the Liver Unit at the Queen Elizabeth Hospital, Birmingham, UK, is to assess posttransplantation alcohol consumption and identify risk factors associated with recidivism. This retrospective case-control study used a self-report questionnaire to assess pretransplantation and posttransplantation drinking, and a retrospective cohort study used patient notes to analyze risk factors for recidivism. Of 64 patients who underwent transplantation for alcoholic liver disease (ALD) between May 1996 and November 1999, a total of 49 surviving patients (40 men, 9 women) were available for study. The comparison group consisted of 49 patients matched for age, sex, and date of transplantation who underwent transplantation for non-alcohol-induced chronic liver disease. Two-year patient survival rates were 82% in both study groups. The questionnaire response rate was 69.3% and 75.5% in patients with and without ALD, respectively. Data on recidivism (defined as any alcohol consumption after transplantation) were available in 46 of the 49 patients with ALD. Of these, 45.6% were drinking; 21.7% reported only occasionally drinking; 17.3%, moderate drinking; and 6.5%, heavy drinking. Information on alcohol consumption was available from 41 of the 49 controls. Of these, 52.5% consumed alcohol; 22.0% reported drinking only on special occasions; 24.4%, moderate drinking; and 4.9%, a return to heavy drinking. However, these differences were not statistically significant, and log-rank analysis found no significant difference in time to resumption of drinking. In the ALD cohort, no significant risk factors were identified to predict recidivism. No pretransplantation risk factors (including period of abstinence before transplantation) correlated with recidivism. Survival after transplantation for ALD is similar to that in other forms of chronic liver disease. Recidivism rates for patients with ALD are high, but patients with ALD do not drink more than their control counterparts posttransplantation. In most instances, alcohol consumption posttransplantation is minimal to moderate (<20 units/wk) and seems to be controlled.

Adult↗
PubMed2001

Role of lateral cephalograms in assessing severity and difficulty of orthodontic cases.

To assess the role of lateral cephalometric films in the evaluation of orthodontic patients, 16 certified orthodontists examined 80 sets of dental casts and lateral cephalograms. The patients included 5 subgroups: Class I with mild crowding, Class II Division 2, Class III, open bites, and bimaxillary protrusion. A 5-point Visual Analogue Scale was used to assess the degree of severity and difficulty of each case. Severity was defined as the degree of deviation from ideal occlusion, while difficulty was defined as the probability of attaining an ideal occlusion when all treatment options were available. The examiner then chose one or more of the following treatment options: growth modification, extraction, nonextraction, and surgery. All examiners scored the degree of severity and difficulty of each case with casts only at Time 1 (T1), then with casts and cephalograms at Time 2 (T2). The observed ratings from the Visual Analogue Scale were scored by using the Rasch model, which transforms the nonlinear ordinal ratings to a linear interval scale. Intersubgroup differences and differences between T1 and T2 difficulty and severity were assessed by using a 5 x 2 repeated measures analysis of variance. A paired t test examined the amount and direction of the differences between T1 and T2 of each subgroup. Multiple contingency tables were used to compare treatment option changes between all subgroups at each time. Severity and difficulty scores highly correlated. Analysis of variance showed significant differences among subgroups for both severity and difficulty; however, there were significant time differences for severity only. Paired t tests revealed a small increase in severity for the bimaxillary protrusive group and small but significant decreases for the subgroups Class II Division 2 and Class III when cephalograms were added. The multicontingency table analysis demonstrated that a significant number of examiners did change their treatment options at T2 for bimaxillary protrusive, nonextraction, and Class II Division 2 patients. It was concluded that lateral cephalometric films showed a significant influence on a clinician's determination on severity of some types of orthodontic malocclusions.

Adolescent↗
PubMed2001

Wavelet transforms of TM joint vibrations: a feature extraction tool for detecting reducing displaced disks.

The objective of this study was to determine if wavelet transforms (WTs) of vibrations recorded from temporomandibular joints (TMJs) with reducing displaced disks could be visually separated from WTs of vibrations recorded from normal TM joints by blinded observers. From a continuous series of 124 diagnosed TMD patients, 28 were confirmed with at least one reducing displaced disk. Vibrations were recorded from each affected joint, together with incisal point movements, using BioPAK (BioResearch, Inc., Milwaukee, WI) during opening, closing, and lateral excursions. Identical recordings were taken from 28 patients who were determined to have normal "nondisplacing, nondisplaced" joints. A 3x7 Biorthogonal Spline Wavelet Transform was used to create three-dimensional time-frequency graphs of the vibration events for each subject. Printed copies of the graphs were then shown sequentially to seven blinded observers who were asked to separate them into two groups without any knowledge of their significance. Each observer was independently able to separate the two groups without committing more than one error. We conclude that the vibrations generated by reducing displaced disks are sufficiently different from the vibrations of normal joints to be separable by visual inspection of their respective wavelet transforms.

Humans↗
PubMed2001

Phase II trial of the use of paclitaxel and gemcitabine as a salvage treatment in metastatic breast cancer.

The purpose of this study was to evaluate gemcitabine plus paclitaxel in heavily pretreated patients with metastatic breast cancer (MBC). Patients with MBC with second or third relapse to anthracycline-containing regimens received a 3-hour infusion of paclitaxel 175 mg/m2 on day 1, and gemcitabine 1.0 g/m2 on days 1, 8, and 15, every 28 days. Because of unacceptable thrombocytopenia seen in the first 5 patients, the gemcitabine schedule was changed to days 1 and 8 (G-1,8) for the remainder of the study, every 21 days. Twenty-nine patients (median age, 46 years; range, 32-68 years) received 137 cycles (median: 4 per patient). The regimen was well tolerated. World Health Organization grades III and IV thrombocytopenia were observed in 5 (18.5%) of the first 27 cycles (G-1,8,15), and in 6 (5.4%) of the 110 subsequent cycles (G-1,8)--p = 0.04 for the difference between schedules. Five patients had grade I and two had grade III neuropathy. Eight patients had grade III neutropenia, two had grade IV neutropenia associated with fever (G-1,8,15), and eight had grades I and II myalgia and fatigue. There were 16 (55%) objective responses (95% CI 36-73%); 5 (17%) complete responses, 11 (38%) partial responses (95% CI 3-30% and 19-56%, respectively), and 6 (20.5%) patients with stable disease. Median response duration was 8 months (range, 4-26 months). Median overall survival was 12 months (range, 4-28+ months), and 1-year and 2-year survival rates were 45% and 30%, respectively. This phase II study demonstrated a manageable toxicity profile with the gemcitabine day 1, 8 schedule in combination with paclitaxel and significant and promising activity in heavily pretreated patients with MBC. A confirmatory phase III trial is warranted.

Adult↗
PubMed2001

Radionuclides in Peconic River fish, mussels, and sediments.

For regulatory oversight and quality control of Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) actions, fish, mussels, and sediments were analyzed from the Peconic River system on Long Island, NY, downstream of the Brookhaven National Laboratory, as well as from control locations. The analyses were for photon-emitting radionuclides (notably 60Co and 137Cs), uranium, plutonium, and americium. Sediments were cored in 4 sections to 0.37 m depth, whole fish were analyzed, and mussels were separated into flesh and shells. Radioisotopes of the cited elements were detected in sediment, some of the fish contained 137Cs, 241Am, and uranium, and mussel flesh contained 137Cs and uranium. All of the 60Co, 233U, and enriched uranium, and some of the 137Cs and 241Am, can most likely be attributed to Brookhaven National Laboratory. The other radionuclides (and some of the 137Cs and 241Am) are believed to have either fallout or nature as their origin. The New York State Department of Health (NYSDOH) evaluated the radiological data in terms of adverse health implications due to consumption of fish with the levels of reported radioactivity. The NYSDOH determined that the added radiation doses likely to result from eating this fish are a small fraction of the radiation dose that normally results from radionuclides present in the body from natural sources.

Animals↗
PubMed2001

Immunohistochemical distinction of endometrial stromal sarcoma and cellular leiomyoma.

Distinguishing low grade endometrial stromal sarcoma (ESS) from benign smooth muscle proliferations like cellular leiomyoma (CL) can be problematic; because of differing treatments and prognosis, this distinction is important. The authors tested the hypothesis that low grade ESS could be distinguished from CL by immunohistochemistry using a panel of antibodies that have not previously been used in this setting. Antibodies to calponin, smooth muscle myosin heavy chain (SMM-HC), the Wilms tumor gene product (WT-1), and CD10 were applied to 14 cases of ESS (10 low grade, 4 high grade) and 9 CL. Among low grade ESS, 3 of 10, 3 of 10, 9 of 10, and 10 of 10 were positive for expression of calponin, SMM-HC, WT-1, and CD10, respectively. Of CL, all 9 were positive for calponin, SMM-HC, and WT-1, whereas 3 of 9 marked with antibodies to CD10. Overall, SMM-HC and calponin were expressed strongly in CL but weakly expressed in ESS; the converse was true for CD10. Expression of WT-1 and the reticulin-staining pattern do not discriminate between these two tumors. Antibodies to SMM-HC, CD10, and calponin can reliably distinguish ESS from CL.

Calcium-Binding Proteins↗
PubMed2001

A novel mouse model of lipotoxic cardiomyopathy.

Inherited and acquired cardiomyopathies are associated with marked intracellular lipid accumulation in the heart. To test the hypothesis that mismatch between myocardial fatty acid uptake and utilization leads to the accumulation of cardiotoxic lipid species, and to establish a mouse model of metabolic cardiomyopathy, we generated transgenic mouse lines that overexpress long-chain acyl-CoA synthetase in the heart (MHC-ACS). This protein plays an important role in vectorial fatty acid transport across the plasma membrane. MHC-ACS mice demonstrate cardiac-restricted expression of the transgene and marked cardiac myocyte triglyceride accumulation. Lipid accumulation is associated with initial cardiac hypertrophy, followed by the development of left-ventricular dysfunction and premature death. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining and cytochrome c release in transgenic hearts suggest that cardiac myocyte death occurs, in part, by lipid-induced programmed cell death. Taken together, our data demonstrate that fatty acid uptake/utilization mismatch in the heart leads to accumulation of lipid species toxic to cardiac myocytes. This novel mouse model will provide insight into the role of perturbations in myocardial lipid metabolism in the pathogenesis of inherited and acquired forms of heart failure.

Animals↗
PubMed2001

Attenuation coefficient and sound speed in human myometrium and uterine fibroid tumors.

OBJECTIVE: To develop a noninvasive method for treatment of uterine fibroid tumors using high-intensity focused ultrasound. Optimal high-intensity focused ultrasound treatment would be dependent on quantitative information about ultrasonic tissue characteristics. METHODS: Ultrasonic attenuation and the sound speed of fresh human fibroid tumors and myometrium were measured as a function of frequency (1-3 MHz) by using a pulse transmission technique before and after in vitro high-intensity focused ultrasound treatment (3.5 MHz at an intensity of 2,000 W/cm2). RESULTS: The ranges of the attenuation coefficients, before and after high-intensity focused ultrasound treatment, were 0.9 to 2.2 and 1.8 to 3.9 dB/cm2, respectively, for fibroid tumors and 0.5 to 1.6 and 1.7 to 3.3 dB/cm2, respectively, for myometrium. Although the sound speed appeared to be independent of frequency (1,611 to 1,616 m/s at 1 to 3 MHz) in both types of tissues, a slight increase of approximately 4 to 14 m/s was observed after high-intensity focused ultrasound treatment. CONCLUSIONS: The results of this study represent our first reported values of the attenuation coefficient and sound speed in fibroid tumors and myometrium before and after high-intensity focused ultrasound treatment.

Acoustics↗
PubMed2001

Gemcitabine and paclitaxel as salvage therapy in metastatic breast cancer.

In a phase II trial, 29 patients with anthracycline-pretreated or anthracycline-resistant metastatic breast cancer in whom anthracycline-containing first- or second-line chemotherapy failed received combination paclitaxel (Taxol)/gemcitabine (Gemzar). The initial regimen of paclitaxel at 175 mg/m2 on day 1 and gemcitabine at 1,000 mg/m2 on days 1, 8, and 15 of a 28-day cycle was given to five patients for a total of 27 cycles. The regimen resulted in excessive thrombocytopenia and was subsequently changed to gemcitabine at the same dose on days 1 and 8 of a 21-day cycle, with study treatment being given for a maximum of eight cycles. This regimen was well tolerated. Further evaluation of this regimen in minimally and heavily pretreated patients with advanced breast cancer is warranted.

Adult↗
PubMed2001

Electromyographic evidence of reduced muscle activity when ULF-TENS is applied to the Vth and VIIth cranial nerves.

The object of this study was to determine if the resting muscle activity of TMD patients with measured hyperactivity (EMGave > 2.0 microvolts) could be reduced by the application of ULF-TENS (Ultra-Low-Frequency-Transcutaneous Electrical Neural Stimulation) [(BioTENS) BioResearch, Inc. Milwaukee, WI]. Twenty-nine patients with resting muscle hyperactivity and ten without resting muscle hyperactivity were selected from a series of 124 consecutively diagnosed TMD patients. Electromyographic records were taken bilaterally (with the mandible at rest) from the superficial masseter, anterior temporalis, anterior digastric, and posterior temporalis muscles before and after the application of ULF-TENS. The EMG data were averaged. For the 85 muscles that were found initially to exceed the usual cutoff of 2.0 microvolts, means and standard deviations were calculated. The "before TENS" levels were: mean = 3.353 +/- 1.44227 and the "after TENS" values were: mean = 1.844 +/- 0.92421. Using a student t-test, we found the difference between the before and after levels significant (p < .0005). Additionally, means and standard deviations were calculated for each muscle (Ta, Mm, etc.) separately and also found to be significantly different (before Vs after TENS). In these "hyperactive" patients, the nonhyperactive muscles were also pooled, the means calculated before (mean = 1.21 +/- 0.456) and after (mean = 1.00 +/- 0.345) TENS and found to be significantly different (p < 0.01). For the ten patients exhibiting no muscle exceeding the 2.0 microvolt cutoff (mean = 1.08 +/- 0.415), no significant change (in levels) was observed after ULF-TENS (mean = 0.96 +/- 0.359; p > 0.88); however, when we calculated the "paired difference," we found a significant reduction, albeit very slight, in these patients' muscles, too. We conclude that ULF-TENS has an activity-reducing effect on the resting EMG levels of both hyperactive and relaxed muscles. It also appears that while the > 2.0 microvolt cutoff is useful for identifying patients that are hyperactive at rest, it does not identify complete relaxation of masticatory muscles.

Adult↗
PubMed2001

[Are there physical, technical and morphological limits to conformational radiotherapy?].

Conformal radiotherapy results from several technical and data processing advances. The treatment planning and the daily treatments have benefited from a significant improvement of the quality control. However, all the steps of the process contain various limitations of varying effects. It appear important to identify, describe and exploit those limits to better drive the procedures and optimise the quality. Identifying the limits of the conformal radiotherapy should be an important help to implement intensity modulation radiotherapy.

Anthropometry↗