PubMed Health⌕ Search

Biomedical subjects

L Jimenez

Publications and source records attributed to L Jimenez.

At least 19 recordsLinked to original sources
PubMed2006

Bone marrow cells can give rise to ameloblast-like cells.

Post-eruptive loss of ameloblasts requires identification of alternative sources for these cells to realize tooth-tissue-engineering strategies. Recent reports showed that bone-marrow-derived cells can give rise to different types of epithelial cells, suggesting their potential to serve as a source for ameloblasts. To investigate this potential, we mixed c-Kit(+)-enriched bone marrow cells with embryonic dental epithelial cells and cultured them in re-association with dental mesenchyme. Non-dividing, polarized, and secretory ameloblast-like cells were achieved without cell fusion. Before basement membrane reconstitution, some bone marrow cells migrated to the mesenchyme, where they exhibited morphological, molecular, and functional characteristics of odontoblasts. These results show, for the first time, that bone-marrow-derived cells can be reprogrammed to give rise to ameloblast-like cells, offering novel possibilities for tooth-tissue engineering and the study of the simultaneous differentiation of one bone marrow cell subpopulation into cells of two different embryonic lineages.

Ameloblasts↗
PubMed2005

In vitro detection of differential and cell-specific hepatobiliary toxicity induced by geldanamycin and 17-allylaminogeldanamycin in rats.

The differential toxicity of two anticancer agents is described using the in vitro rat liver slice culture model. Liver slices from F-344 rats were cultured for 5 days in Waymouth's-based medium with exposure to a range of geldanamycin (GEL) or 17-allylaminogeldanamycin (17-AAG) concentrations. GEL induced concentration-dependent reduction of alkaline phosphatase and of gamma-glutamyl transferase levels, which are indicators of biliary epithelial cell(s) (BEC) viability, and exhibited hepatocellular toxicity at higher concentrations. Histologically, BEC cell injury was evident at the lowest GEL concentration (0.1 microM) and progressed to overt bile duct necrosis at 5 microM, a level at which hepatocellular damage was also more prominent. Slices exposed to the same concentrations were more sensitive to toxic effects of GEL than of 17-AAG. 17-AAG at the lowest concentration had more slice biomarker retention than GEL, and histological analysis revealed minimal toxic effect on BEC. With increasing concentration, BEC were progressively lost, and BEC proliferation was completely inhibited at 5 microM 17-AAG. Hepatocellular injury was evident only at high dose exposures. This is believed to be the first use of an in vitro liver tissue model to accurately predict the differential and concentration-dependent toxicities of these compounds.

Alanine Transaminase↗
PubMed2005

Contribution of NTRK2 to the genetic susceptibility to anorexia nervosa, harm avoidance and minimum body mass index.

Anorexia nervosa (AN) and bulimia nervosa (BN) are eating disorders (ED) with complex genetic and environmental components. Genetic studies and animal models support the participation of brain-derived neurotrophic factor (BDNF) in the vulnerability to AN and BN. We investigated the genetic contribution of the BDNF-specific receptor neurotrophic tyrosine kinase receptor type 2 (NTRK2) to the susceptibility to ED. We have screened the entire NTRK2 gene in 91 patients with ED and have identified 14 single-nucleotide polymorphisms (SNPs). A population-based association study with six SNPs from the NTRK2 locus was performed in 164 ED patients and 121 controls. Significant evidence of association for markers -69C>G and IVS13+40G>A was detected. We also observed a strong association between the C-A-insC haplotype (-69/IVS13+40/2784-2785) and binge-eating/purging AN (ANP, P=0.006; OR=2.27), and a reduced frequency of haplotype G-A-delCl in BN patients (P=0.034; OR=0.6). The analysis of ED-related phenotypes revealed a clear association between NTRK2, high scores of Harm avoidance measured by the temperament and character inventory (TCI-R; P=0.003) and minimum body mass index (minBMI; P<0.001). Our data support a contribution of NTRK2 to the genetic susceptibility of ED, mainly ANP, and ED-related phenotypic traits, such as Harm avoidance and minBMI.

Adult↗
PubMed2000

Use of PCR analysis for detecting low levels of bacteria and mold contamination in pharmaceutical samples.

PCR assays were developed and compared to standard methods for quality evaluation of pharmaceutical raw materials and finished products with low levels of microbial contamination. Samples were artificially contaminated with less than 10 CFU of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Aspergillus niger. Bacterial DNA was extracted from each enrichment broth by mild lysis in Tris-EDTA-Tween 20 buffer containing proteinase K while mold DNA was extracted by boiling samples in Tris-EDTA-SDS buffer for 1 h. A 10-microl aliquot of extracted DNA was added to Ready-To-Go PCR beads and specific primers for E. coli, S. aureus, and P. aeruginosa. However, 50-microl aliquots of extracted mold DNA were used for amplification of specific A. niger DNA sequences. Standard methods required 6-8 days while PCR detection of all microorganisms was completed within 27 h. Low levels of microbial contamination were detected in all raw materials and products using PCR assays. Rapid quality evaluation of pharmaceutical samples resulted in optimization of product manufacturing, quality control, and release of finished products.

Aspergillus niger↗
PubMed2000

Exercise does not induce oxidative stress in trained heart transplant recipients.

PURPOSE: The objectives of this study were twofold: 1) to determine the effect of incremental exercise to volitional fatigue on plasma levels of lipid peroxidation (malondialdehyde) in heart transplant recipients (HRT) and 2) to examine blood antioxidant capacity in HTR by assessment of antioxidant enzyme activities and vitamin E levels. METHODS: Seven endurance-trained HTR (mean +/- SD; age 39.7 +/- 12.8 yr) and seven endurance-trained healthy, age-matched control subjects (HC) (mean age 40.6 +/- 10.7 yr) performed a symptom-limited incremental exercise test on a cycle ergometer. Venous blood samples were obtained at rest, exercise, and during recovery and analyzed for plasma levels of malondialdehyde (MDA) as well as markers of blood antioxidant capacity. After exercise and during recovery, all dependent measures were corrected for plasma volume changes induced by exercise. Significance was established at (P < 0.05). RESULTS: No group differences existed in plasma levels of MDA at rest. Further, graded exercise did not alter plasma levels of MDA in either group. Resting erythrocyte glutathione peroxidase (GPX) activity was significantly lower and erythrocyte superoxide dismutase (SOD) activity was higher in HTR compared with HC. Finally, at rest, no group differences existed in plasma GPX activity or vitamin E levels. CONCLUSIONS: Graded exercise to fatigue does not promote an increase in oxidative stress in blood of exercise trained HTR. Therefore, physical exercise does not appear to pose an oxidative-stress risk for these patients.

Adult↗
PubMed1995

Will young children comply and follow instructions to successfully wear soft contact lenses?

We fit eighty-five children between the ages of 11 years and 13 years, 11 months with soft contact lenses to study safety of soft contact lens wear in children. We report the results at 6 months of a 3 year longitudinal study. Contact lens care compliance, a critical factor in successful lens wear, was evaluated using a questionnaire. The questionnaire was completed by 74 subjects at dispensing and at 1-week and 6-months post-dipensing visits. Subjects found contact lens removal to be the easiest and lens insertion the most difficult procedures. After 6 months, 85% of the children correctly identified the purpose of lens care solutions, 90% knew that daily cleaning was necessary, 96% understood lens disinfection, and 99% expressed confidence in their ability to care for their lenses.

Adolescent↗
PubMed1992

Soluble and membrane-bound Met-enkephalin degrading peptidases in Mytilus edulis hemolymph.

Recent reports have provided strong evidence indicating that Met-enkephalin is serving as a neuroimmune modulator. It acts as a bidirectional signal molecule in transmitting message between the endocrine system and the immune cells in the circulating fluid. In this study, we investigated peptidases which are capable of degrading Met-enkephalin in the hemolymph fluid and hemocyte membrane. Our results showed that aminopeptidase is present at a high level in the fluid and a low level in the membrane. Carboxypeptidase is not present in the fluid but it is present at a level higher than that of aminopeptidase in the membrane. Either ACE or neutral endopeptidase is also present in the hemolymph fluid and hemocyte membrane. Functional role of these peptidases in the overall scheme of the neuroimmune mechanism is currently under investigation.

Amino Acid Sequence↗
PubMed1990

Endothelin releasing activity in calf serum and porcine follicular fluid.

Bovine calf serum (CS) and porcine follicular fluid (PFF) added to bovine aortic endothelial cells (BAEC) in culture stimulate endothelin (ET) release. Sorbent extraction of acidified calf serum and PFF using Bond Elut C18 yields a product with an activity 30% that of the starting material. Fractionation of Bond Elut C18 extracted CS or PFF using HPLC yields peaks of activity with retention times similar to those of TGF beta and activin A, respectively. TGF beta is 10-fold more potent than activin A to stimulate ET release from BAECs. The observation that TGF beta and activin A are dose-additive but not effect-additive to stimulate ET release is compatible with the conclusion that these two substances act through a similar mechanism. Thus, TGF beta and/or activin A-related peptides may contribute to the ET releasing activity observed in acidified Bond Elut C18 extracted CS and PFF. The identity of ET-releasing activity in native CS and PFF remains to be established.

Activins↗
PubMed1984

Intraepithelial leukocytes in the Myotis myotis mammary gland.

The morphological and ultrastructural characteristics of intraepithelial leukocytes in the alveolar epithelium of the mammary gland were described in female bats during late pregnancy and lactation. Intraepithelial lymphocytes were principally located in the basal portion of the alveolar epithelium, intermixed with alveolar epithelial cells. They exhibited a spherical shape, with some cytoplasmic prolongations or pseudopodia in association with adjacent epithelial cells. Some eosinophils were observed in the alveolar epithelium of the Myotis myotis mammary gland during the above mentioned periods. Eosinophils often presented pseudopodia that projected themselves between the epithelial cells. In addition, cells of the lymphoid series were observed in the alveol and ductal lumina, forming an integral part of the secreted material (mammary exosecretion).

Animals↗
PubMed1984

Interstitial cells of Myotis myotis ovary during gestation. An ultrastructural study.

The purpose of this paper was to describe the ultrastructure of the interstitial cells of the bat ovary (Myotis myotis) during gestation (May and June). The Myotis myotis ovary has great amounts of interstitial tissue comprising of polyhedral elements with abundant cytoplasm filled with lipid droplets. Large mitochondria with an unusual parallel arrangement of the tubular cristae were observed. They consisted in four or five piled tubular elements. Numerous concentrically disposed agranular membranes were observed. The occupied large cytoplasm areas around some lipid droplets. These three strictly associated cellular components are interpreted as the expression of the steroidogenic activity of the interstitial cells.

Animals↗