Search PubMed⌕ Search

Biomedical subjects

J Luna

Publications and source records attributed to J Luna.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of a rapid culture method for tuberculosis diagnosis: a Latin American multi-center study.

SETTINGS: Tuberculosis (TB) diagnostic laboratories in Latin America. OBJECTIVES: Evaluation of thin-layer agar (TLA) compared to Löwenstein-Jensen (LJ) culture for the diagnosis of TB. DESIGN: Phase II prospective study in six laboratories. Samples included sputum and extra-pulmonary specimens from patients with a clinical diagnosis of TB. Respiratory samples were decontaminated using NaOH/ NALC; all samples were centrifuged, stained with Ziehl-Neelsen for acid-fast bacilli (AFB), cultured on LJ and TLA and identified according to recommended procedures. Sensitivity and likelihood ratios (LR), growth detection time and contamination rate were calculated for both media. RESULTS: A total of 1118 clinical specimens were studied. Cultures detected Mycobacterium tuberculosis in all AFB-positive samples, whereas for AFB-negative specimens LJ detected 3.2% and TLA 4.4%. Sensitivity was 92.6% (95%CI 87.9-95.9) and 84.7% (95%CI 78.8-89.0) for TLA and LJ, respectively. Positive and negative LRs were similar. Contamination was 5.1% for TLA and 3.0% for LJ. Median time to detection of a positive culture was 11.5 days (95%CI 9.3-15.0) for TLA and 30.5 days (95%CI 26.9-39.0) for LJ (P < 0.0001). CONCLUSION: Difference in the characteristics of the participating laboratories, the disease prevalence and the number and type of specimens processed did not affect the overall performance of TLA as compared to LJ, supporting the robustness of the method and its feasibility in different laboratory settings.

Agar↗
PubMed2004

Silymarin induces recovery of pancreatic function after alloxan damage in rats.

Alloxan has been widely used to produce experimental diabetes mellitus syndrome. This compound causes necrosis of pancreatic beta-cells and, as is well known, induces oxidant free radicals which play a relevant role in the etiology and pathogenesis of both experimental and human diabetes mellitus. Previously we have reported hypoglycemic and antilipoperoxidative actions of silymarin in serum and pancreatic tissue respectively. The aim of this study was to test whether silymarin could reduce the hyperglycemia and revert the pancreatic damage in alloxan treated rats, tested with silymarin in two protocols: using both compounds simultaneously for four or eight doses, or using the compound 20 days after alloxan administration for 9 weeks. Serum glucose and insulin were determined, and pancreatic fragments were used for histology and insulin immunohistochemistry. Pancreatic islets were isolated to assess insulin and Pdx1 mRNA expression by RT-PCR. Our results showed that 72 hours after alloxan administration, serum glucose increased and serum insulin decreased significantly, whereas pancreatic tissue presented morphological abnormalities such as islet shrinkage, necrotic areas, loss of cell organization, widespread lipoid deposits throughout the exocrine tissue, and loss of beta cells, but insulin and glucagon immunoreactivity was scattered if any. In contrast the pancreatic tissue and both insulin and glucose serum levels of rats treated with silymarin were similar to those of control animals. In addition, insulin and glucagon immunoreactive cells patterns in Langerhans islets were also normal, and normal insulin and Pdx1 mRNA expression patterns were detected during pancreatic recovery in Langerhans islets. The overall results suggest that silymarin induces pancreatic function recovery demonstrated by insulin and glucagon expression protein and normoglycemia after alloxan pancreatic damage in rats.

Animals↗
PubMed2002

Lymphocytes and T lymphocyte subsets are regionally distributed in the female goat reproductive tract: influence of the stage of the oestrous cycle.

The reproductive tract of the female is a part of the mucosal system which protects from pathogens invasion. We have analysed the presence and distribution of total lymphocytes, plasma cells (antibody secreting B cells) and T lymphocytes subsets in the reproductive tract of the female goat. The influence of the oestrous cycle on the densities of lymphocytes and plasma cells of the cervix and uterus horn was evaluated in sections prepared for conventional histology. Immunocytochemistry was used for the study of lymphocyte subsets by confocal microscopy and immunoperoxidase techniques. Present results show that the reproductive tract of the goat is a site rich in lymphocytes. These cells were found mingled with the epithelial cells of the endometrium and distributed throughout the stroma. Lymphocyte aggregates were observed in the stroma. Lymphocyte but not plasma cell number changed depending on the reproductive stage of the goats. The impact of the hormonal environment was different for the cervix and uterine horn. Immunocytochemistry studies evidenced the presence of cells displaying immunoreactivity for both CD 4+ and CD 8+ antibodies in the epithelial layer and stroma of the cervix and uterine horn. These cells were more numerous in the cervix and were also found infiltrating the luminal epithelia of endometrial glands. Overall, our results indicate that lymphocyte distribution is different in the cervix and the horn, and is influenced by the stage of the reproductive cycle. In summary, CD 4+ and CD 8+ T lymphocytes subsets could be found in the endometrium of both the cervix and uterine horn of the goat reproductive tract.

Animals↗
PubMed2001

Fractional flow reserve compared with intravascular ultrasound guidance for optimizing stent deployment.

BACKGROUND: Determination of fractional flow reserve (FFR) has been proposed as a means to assess stent deployment. In this prospective, multicenter trial, we evaluate the use of FFR to optimize stenting by comparing it with standard intravascular ultrasound (IVUS) criteria. METHODS AND RESULTS: Eighty-four stable patients with isolated coronary lesions underwent coronary stent deployment starting at 10 atm and increased serially by 2 atm until the FFR was >/=0.94 or 16 atm was achieved. IVUS was then performed. FFR was measured with a coronary pressure wire with intracoronary adenosine to induce hyperemia. The diagnostic characteristics of an FFR <0.94 to predict suboptimal stent expansion by IVUS, defined in both absolute and relative terms, were calculated. Over a range of IVUS criteria, the highest sensitivity, specificity, and predictive accuracy of FFR were 80%, 30%, and 42%, respectively. Receiver operator characteristic analysis defined an optimal FFR cut point at >/=0.96; at this threshold, the sensitivity, specificity, and predictive accuracy of FFR were 75%, 58%, and 62%, respectively (P=0.03 for comparison of predictive accuracy, P=0.01 for concordance between FFR and IVUS). The negative predictive value was 88%. Significantly better diagnostic performance was achieved in a subgroup that received higher doses (>30 microgram) of intracoronary adenosine during pressure measurements, suggesting that FFR might be overestimated in the other group. CONCLUSIONS: A fractional flow reserve <0.96, measured after stent deployment, predicts a suboptimal result based on validated intravascular ultrasound criteria; however, an FFR >/=0.96 does not reliably predict an optimal stent result. Higher doses of intracoronary adenosine than previously used to measure FFR improve these results.

Adenosine↗
PubMed2001

Regional and temporal progression of reactive astrocytosis in the brain of the myelin mutant taiep rat.

Reactive astrocytosis in taiep rats was shown by glial fibrillary acidic protein (GFAP) immunoreactivity measured by means of enzyme-linked immunosorbent assay and indirect immunofluorescence. Increased GFAP immunoreactivity was first observed in the brainstem of 15-day-old taiep rats and was widespread throughout all brain regions at 6 months of age. Characteristically, astrocytes were hypertrophic and displayed strong GFAP fluorescence. The pattern of these reactive cells may correlate with the process of dysmyelination in the taiep rat.

Animals↗
PubMed2001

Biochemical and histochemical analysis of 71 kDa dystrophin isoform (Dp71f) in rat brain.

Dp71 is a member of the dystrophin family and the most abundant dmd gene product in the brain. In the present study, we focused on a short dystrophin transcript named Dp71f, which is alternatively spliced when exon 78 is absent The topographic localization of this protein in the encephalon has not been properly described yet, nor its cellular or subcellular localization, and even less its functions. Dp71f was found to be a cytoplasmic 70 kDa protein and localized in all encephalon regions studied. Double labeling using specific markers for various cell types confirmed Dp71f distribution in the cytoplasm of all cell types studied. Labeling was more conspicuous near the nucleus and diminished towards the periphery of cells. In some cases, we observed cells that were positive for actin and Dp71f in regions corresponding to lamellipodia-like structures. Dp71f and Dp71d isoforms were differently distributed. Our study is the first specific and unambiguous description of the topography and cellular localization patterns of Dp71f in brain, suggesting that Dp71f is a ubiquitous protein.

Animals↗
PubMed2001

Plasmid-encoded toxin of enteroaggregative Escherichia coli is internalized by epithelial cells.

We have previously described a 104-kDa protein termed Pet (for plasmid-encoded toxin) secreted by some strains of enteroaggregative Escherichia coli (EAEC). Through an unknown mechanism, this toxin (i) raises transepithelial short-circuit current (Isc) and decreases the electrical resistance of rat jejunum mounted in the Ussing chamber, (ii) causes cytoskeletal alterations in HEp-2 cells and HT29/C1 cells, and (iii) is required for histopathologic effects of EAEC on human intestinal mucosa. Pet is a member of the autotransporter class of secreted proteins and together with Tsh, EspP, EspC, ShMu, and SepA proteins comprises the SPATE subfamily. Here, we show that Pet is internalized by HEp-2 cells and that internalization appears to be required for the induction of cytopathic effects. Evidence supporting Pet internalization includes the facts that (i) the effects of Pet on epithelial cells were inhibited by brefeldin A, which interferes with various steps of intracellular vesicular transport; (ii) immunoblots using anti-Pet antibodies detected Pet in the cytoplasmic fraction of intoxicated HEp-2 cells; (iii) Pet was detected inside HEp-2 cells by confocal microscopy; and (iv) a mutant in the passenger domain cleavage site, which prevents Pet release from the bacterial outer membrane, did not produce cytopathic effects on epithelial cells, whereas the release of mutant Pet from the outer membrane with trypsin yielded active toxin. We have also shown that the Pet serine protease motif is required to produce cytopathic effects but not for Pet secretion. Our results suggest an intracellular mode of action for the Pet protease and are consistent with we our recent report suggesting an intracellular mode of action for Pet.

Amino Acid Motifs↗
PubMed2000

Clinical trial evaluating a new hub device designed to prevent catheter-related sepsis.

A new commercial hub device designed to minimise catheter-related infections was evaluated in a prospective, randomised trial in the intensive care and surgical units of the Hospital de Tortosa Verge de la Cinta in patients in whom the central venous catheters were expected to remain indwelling for at least 7 days. The assessments conducted at catheter withdrawal included cultures of the skin at the catheter site and cultures of the catheter tip and the catheter hubs; moreover, in cases of suspected catheter-related sepsis, samples of peripheral blood and infusion solutions were also cultured. Of the 130 catheters evaluated, 26 (20%) were withdrawn because of suspected catheter-related sepsis; 10 (15%) were in the control group and 16 (24%) in the new product group. Catheter-related sepsis was diagnosed in nine patients, six of whom were in the new product group and three in the control group; all infections in the former group and only one in the latter group were caused by the catheter connection. The rates of catheter hub colonisation (10 cfu) and catheter colonisation (15 cfu in semiquantitative culture and/or >1,000 cfu in quantitative culture) of hub origin were not significantly different between the groups (15 cases in the control group vs. 20 cases in the new product group, and 5 cases in the control group vs. 11 cases in the new product group, respectively). The data indicate that the use of the new catheter hub device is no more effective in preventing catheter-related infection than standard good clinical procedures.

Aged↗
PubMed2000

Tight junction proteins ZO-1, ZO-2, and occludin along isolated renal tubules.

BACKGROUND: Tight junctions play a critical role in tubular function. In mammalian kidney, the transepithelial electrical resistance and the complexity of the tight junction increase from the proximal to the collecting tubule. The differential expression of three tight junction proteins, ZO-1, ZO-2, and occludin, along isolated rabbit renal tubules is examined in this article. METHODS: Microdissected rabbit renal tubules were processed for immunofluorescence detection of ZO-1, ZO-2, and occludin. The quantitation of these proteins was done by Western blot determinations in Percoll isolated tubules. RESULTS: ZO-1 stained cell boundaries independently of the identity of the tubule. However, the amount found in distal segments was significantly higher than that expressed in proximal regions. ZO-2 in the proximal region was found diffusely distributed in the cytoplasm, with faint staining at cell borders, while a clear signal at cell perimeters was detectable from the Henle's loop to collecting tubules. Nuclear staining of ZO-2 was found along the whole nephron. The presence of occludin at the proximal region was faint and discontinuous, while its expression in the more distant portions was conspicuous. The quantity of ZO-2 and occludin present at the distal region was significantly higher compared with the proximal segment. CONCLUSIONS: The distribution of ZO-1, ZO-2, and occludin follows the increase in junction complexity encountered in renal tubules. The amount of the three proteins found in proximal and distal segments is significantly higher in the latter.

Animals↗
PubMed1999

TT virus is present in a high frequency of Italian hemophilic patients transfused with plasma-derived clotting factor concentrates.

The prevalence of the blood-borne TT virus (TTV) in Italian hemophiliacs treated with different preparations of factor VIII was determined. Of the 178 hemophilic patients (mean age, 29 years), TTV-DNA was found in 123 (69%), in comparison to 22 of 100 (22%) blood donors (P <.0001). Of the 123 patients who tested positive for TTV, significant numbers were also infected with human hepatitis viruses and/or human immunodeficiency virus (HIV): 31% had TTV and hepatitis C virus (HCV), 22% had TTV, and at least 2 of the 4 known human blood-borne viruses tested, whereas 15% had TTV alone. The risk of acquiring TTV alone was only slightly higher in recipients of unmodified plasma factor concentrates (78%, odds ratio, 1.24; 95% confidence interval [CI], 0.27 to 5.79) than in patients treated with virus inactivated concentrates (67%), whereas the risk was significantly lower in recipients of recombinant factors (11%, odds ratio, 0.09; 95% CI, 0.01 to 0.52). Serum alanine aminotransferase (ALT) levels were elevated in 2 of 27 patients (7%) with TTV alone compared with 43 of 56 patients (77%) coinfected with TTV and HCV and compared with 16 of 21 patients (76%) with HCV alone. Taken together, these results indicate that TTV frequently infects Italian hemophiliacs treated with plasma-derived factor VIII concentrates, both unmodified and virus-inactivated. Our results do not suggest a causal effect of TTV on chronic liver disease in these patients.

Adolescent↗
PubMed1999

Neurotensin-SPDP-poly-L-lysine conjugate: a nonviral vector for targeted gene delivery to neural cells.

We report herein the synthesis of a novel DNA delivery system and in vitro evidence of its ability to transfect cell lines by binding to the high-affinity neurotensin receptor and subsequent internalization of ligand-receptor complexes. The targeting vehicle consisted of neurotensin crosslinked with poly-L-lysine via N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP). The SPDP-derivatives with either neurotensin or poly-L-lysine were purified by gel filtration. The conjugate resulting of the reaction of neurotensin-SPDP with HS-SPDP-poly-L-lysine was purified through Biogel A 1.5. The neurotensin-SPDP-poly-L-lysine conjugate was able to bind plasmidic DNAs (pSV2cat and pGreen Lantern-1) at optimal molar ratios of 1:5 and 1:6 (DNA: conjugate), respectively. The conjugate internalized those plasmids in the cell lines (N1E-115 and HT-29) bearing the high-affinity neurotensin receptor. Expression of the plasmid products, chloramphenicol acetyltransferase and green fluorescent protein, was observed in such cell lines. Both internalization and expression of the plasmids transferred by the neurotensin-SPDP-poly-L-lysine conjugate were prevented by neurotensin (1 microM) and SR-48692 (100 nM), a specific antagonist of the high-affinity neurotensin receptor. The neurotensin-SPDP-poly-L-lysine conjugate was unable to transfect cell lines lacking the neurotensin receptor (COS-7 and L-929). In rat brain, the high-affinity neurotensin receptor is expressed by specific neurons such as those of the nigrostriatal and mesolimbic dopaminergic systems. Therefore, the neurotensin-SPDP-poly-L-lysine conjugate could be a useful tool for gene delivery to those neuronal systems.

Animals↗
PubMed1999

Developmental changes in LH secretion by male pituitaries in vitro: from the infantile to adult period.

The secretion of LH from the anterior pituitary of male rats was studied at different periods of postnatal development. According to an established classification we used rats 14 (infantile), 23 (juvenile), 45 (pubertal) and 90 (adult) days old. By using an in vitro incubation system, both basal and stimulated LH secretion were studied in the same gland. Age-related differences were observed in basal LH secretion, with juvenile and pubertal pituitaries showing higher secretion compared with infantile and adult pituitaries. However, the GnRH-induced secretory response was significantly higher in the infantile rats than in other ages. LH secretion was also studied in primary cultures from infantile or adult pituitaries. In 24 and 48 h cultures, infantile cells showed a significantly larger response to GnRH than that of adult cells. In the infantile pituitary LH-immunopositive cells showed differences in size at different locations in the gland. At the periphery of the lobes the predominant cells were smaller and angular shaped, whereas in the center of the gland the majority of the cells were ovoid shaped. In the adult pituitary, the predominant LH-positive cells were ovoid in shape and larger in size. Furthermore, 10% more LH-positive cells were observed in infantile pituitaries. On the basis of these data we propose that at the infantile period the male rat pituitary has two populations of LH-secreting cells, one with adult secretory function and shape and a second with increased sensitivity to GnRH and with a morphology atypical of the adult cell. The results presented support the hypothesis that the infantile period is a transitional stage in the rat pituitary development.

Analysis of Variance↗
PubMed1998

Use of microscopical techniques in the study of human chondrocytes from osteoarthritic cartilage: an overview.

Several microscopical techniques, such as high resolution light microscopy, Normaski microscopy, laser confocal and transmission electron microscopy, were used in a correlative morphological study of human osteoarthritic (OA) cartilage. Emphasis was made on the characterization of chondrocytes heterogeneity observed in this tissue. Novel findings were assessed in the morphological and immunocytological study of the chondrocytes organized in aggregates or "clones" typical of this degenerative disease, consisting of the modification of certain elements of the cytoskeleton that influence changes in the cell shape. Also, the presence of cilia and centrioles found in certain cell raised the question if chondrocytes are able to move and regroup as an alternative mechanism to mitosis in the formation of cell clusters or "clones." The presence of two types of secretory chondrocytes was observed and discussed. The use of a correlative approach of several microscopical techniques in a systematic morphological and immunocytological characterization of chondrocyte population within the fibrillated and nonfibrillated human osteoarthritic cartilage gave complementary information that could be important for a better understanding of the histopathogenesis of OA.

Cartilage, Articular↗
PubMed1998

Altered glycosylation pattern of proteins in Alzheimer disease.

Post-translational modifications due to glycosylation of proteins in human brains from patients with Alzheimer disease (AD) were analyzed using lectin histochemistry. Results indicate a significant increase in the production of O-glycosylated (containing Galbeta1,3GalNAc alpha1,0 Ser/Thr or GalNAc alpha1,0 Ser/Thr) proteins in neuritic plaques and neurofibrillary tangles which are the major histopathological hallmarks of AD brains. These alterations were determined by positive labelling with lectins obtained from Amaranthus leucocarpus (ALL) and Macrobrachium rosenbergii (MRL) respectively. Immunohistochemistry indicated that the lectin-staining labelled specifically both neurofibrillary tangles and neuritic plaques. In contrast, lectins labelling was restricted to microvessels in normal control brains. These results provide evidence that modifications of the specific glycosylation patterns are closely related with the presence of the hallmark lesions of this disease, suggesting that an abnormal enzymatic processing of proteins may be an early event in the neuronal degeneration which characterises AD.

Aged↗
PubMed1997

Functional transplant of megabase human immunoglobulin loci recapitulates human antibody response in mice.

We constructed two megabase-sized YACs containing large contiguous fragments of the human heavy and kappa (kappa) light chain immunoglobulin (Ig) loci in nearly germline configuration, including approximately 66 VH and 32 V kappa genes. We introduced these YACs into Ig-inactivated mice and observed human antibody production which closely resembled that seen in humans in all respects, including gene rearrangement, assembly, and repertoire. Diverse Ig gene usage together with somatic hypermutation enables the mice to generate high affinity fully human antibodies to multiple antigens, including human proteins. Our results underscore the importance of the large Ig fragments with multiple V genes for restoration of a normal humoral immune response. These mice are likely to be a valuable tool for the generation of therapeutic antibodies.

Amino Acid Sequence↗
PubMed1996

A factorial design to determine the effects of some variables in the long-term stability of methylmercury standard solutions in water.

A factorial composite design has been employed for a rapid exploration of the effect of some parameters on the stability of spiked methylmercury iodide solutions. The analysis has been performed by capillary gas chromatography with electron-capture detection. The results obtained by the factorial and the univariate methods are in a good agreement. Although, the factorial design does not allow a discrimination of the significance among the same kind of factors, it greatly reduces the number of experiments when the different variables are investigated.

Journal Article↗
PubMed1996

Accuracy of high-resolution CT in identifying chronic pulmonary thromboembolic disease.

OBJECTIVE: The aims of this study were to determine the reliability of the high-resolution CT (HRCT) appearance of the lung parenchyma in distinguishing patients with chronic pulmonary thromboembolism (CPTE) from those with other pulmonary diseases and to compare HRCT with radionuclide scanning. SUBJECTS AND METHODS: Sixty-seven patients for whom HRCT scans were available for review were included in the study. Twenty-eight had proven pulmonary arterial hypertension (PAH), 17 cases of which were caused by CPTE, and 39 had other pulmonary abnormalities. Diagnosis based on the HRCT appearance was attempted by two radiologists, who independently evaluated pulmonary parenchyma for a mosaic pattern of variable attenuation, for a measurable disparity in the size of pulmonary vessels, and for the presence of peripheral scars. HRCT findings were compared with radionuclide scan findings and pulmonary angiography findings. RESULTS: For both readers (readers 1 and 2), sensitivity (94% and 100%, respectively) and specificity (96% and 98%, respectively) were high for distinguishing patients with CPTE from patients with other pulmonary abnormalities, including those with nonthromboembolic PAH. The average ratios of segmental vessel size were 2.2 for patients with CPTE and 1.1 for those with nonthromboembolic diseases. Mosaic attenuation was identified in all patients with CPTE but was also seen in 22% (reader 1) and 14% (reader 2) of patients with no evidence of CPTE. Radionuclide scans revealed a high probability for pulmonary emboli for all but one patient with CPTE but also revealed a high probability for three patients who had no emboli. CONCLUSION: HRCT findings of disparity in the size of segmental vessels and a mosaic pattern of variable attenuation reliably distinguished patients with CPTE from those with nonthromboembolic PAH and from those with other pulmonary abnormalities. In addition, HRCT was more specific than radionuclide scanning in identifying patients with CPTE.

Adolescent↗