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Biomedical subjects

A Hidalgo

Publications and source records attributed to A Hidalgo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Chemokine stromal cell-derived factor-1alpha modulates VLA-4 integrin-dependent adhesion to fibronectin and VCAM-1 on bone marrow hematopoietic progenitor cells.

Stromal cell-derived factor-1alpha (SDF-1alpha) is a potent chemoattractant for hematopoietic progenitor cells (HPC), suggesting that it could play an important role during their migration within or to the bone marrow (BM). The integrin VLA-4 mediates HPC adhesion to BM stroma by interacting with CS-1/fibronectin and VCAM-1. It is required during hematopoiesis and homing of HPC to the BM. As HPC migration in response to SDF-1alpha might require dynamic regulation of integrin function, we investigated if SDF-1alpha could modulate VLA-4 function on BM CD34(hi) cells.CD34(hi) BM cells and hematopoietic cell lines were tested for the effect of SDF-1alpha on VLA-4-dependent adhesion to CS-1/fibronectin and VCAM-1, as well as to BM stroma. CD34(hi) BM cells that adhered to VLA-4 ligands after SDF-1alpha treatment were characterized in colony-forming and long-term culture-initiating cell (LTC-IC) assays.SDF-1alpha rapidly (1 minute) and transiently upregulated the adhesion of CD34(hi) BM cells and hematopoietic cell lines to both CS-1/fibronectin and VCAM-1, and to BM stromal cells. The upregulation of VLA-4-dependent cell adhesion by SDF-1alpha targeted primitive LTC-IC as well as committed CD34(hi) cells. SDF-1alpha-triggered enhancement in VLA-4 function was inhibited by pertussis toxin (PTx) and cytochalasin D, indicating the involvement of G(i) protein downstream signaling and an intact cytoskeleton. Instead, activation of p44/42 MAP kinases by SDF-1alpha did not functionally correlate with enhancement of VLA-4-dependent cell adhesion. Modulation of VLA-4-mediated CD34(hi) BM cell adhesion by SDF-1alpha could play a key role in their migration within and to the BM and therefore influence their proliferation and differentiation.

Animals↗
PubMed2001

The Drosophila neuregulin vein maintains glial survival during axon guidance in the CNS.

Neuron-glia interactions are necessary for the formation of the longitudinal axon trajectories in the Drosophila central nervous system. Longitudinal glial cells are required for axon guidance and fasciculation, and pioneer neurons for trophic support of the glia. Neuregulin is a neuronal molecule that controls glial survival in the vertebrate nervous system. The Drosophila protein Vein has structural similarities with Neuregulin. We show here that Vein functions like a Neuregulin to maintain glial cell survival. We present direct in vivo evidence at single-cell resolution that Vein is produced by pioneer neurons and maintains the survival of neighboring longitudinal glia. This mechanism links axon guidance to control of glial cell number and may contribute to plasticity during the establishment of normal axonal trajectories.

Animals↗
PubMed2001

Reaction between albumen and 3,3',5,5'-tetramethylbenzidine as a method to evaluate egg freshness.

The 3,3',5,5'-tetramethylbenzidine colorimetric test is proposed as a method for the evaluation of shell egg freshness. A simplification of the original method was tested on albumen, and the modified method was used to study the development of albumen-tetramethylbenzidine reaction in eggs stored at three temperatures for different times. The stability of the reagent solution and the repeatability of the analytical method were also studied. The reaction mechanism showed the predominant role of iron ions on the colorimetric response, and the secondary role of copper ions added to the reaction mix in order to enhance the response. The response coefficient of variation, due to the natural variability in eggs laid by hens of two breeds and different ages, was 10.3%, which is similar to the value obtained for furosine, but lower than those previously observed for other egg freshness indices such as Haugh Unit and air-cell height.

Animals↗
PubMed2001

Culture of porcine hepatocytes: the dogma of exogenous matrix revisited.

The use of exogenous matrices has been described as an essential component in securing the viability and functionality of hepatocytes in vitro whether cultured for extracorporeal devices or cell transplantation. Here we report on the in vitro culture of porcine hepatocytes in polystyrene tissue-culture flasks without exogenous matrices showing adequate attachment and viability. Cell proliferation was evidenced by uptake of 5-bromo-2'-deoxyuridine, with peaks at Days 2 (19.7 +/- 8.5%), 15 (20.8 +/- 3.3%), and 35 (21.4 +/- 0.3%). Detoxification capacity was assessed by determination of monoethylglycinexylidide, a product of lidocaine metabolism (highest value 156.5 +/- 10.1 ng/ml at Day 4), and by diazepam clearance (maximum clearance 66.2% at Day 6). Diazepam metabolite levels were highest at Day 4 both for temazepam and oxazepam (6.5 +/- 0.1 and 0.10 +/- 0.01, respectively). These results suggest that the need for an exogenous matrix to achieve sustained proliferative activity and differentiated hepatocyte function should not necessarily be considered a sine qua non condition.

Animals↗
PubMed2001

Prospective evaluation of esophageal motor dysfunction in Down's syndrome.

OBJECTIVE: The aim of this study was to determine the prevalence and way of presentation of esophageal motor dysfunction in a nonselected population of subjects with Down's syndrome. METHODS: The study was conducted in 58 Down's syndrome patients and 38 healthy controls. A global symptom score and individual scores for dysphagia for liquids and solids, heartburn, vomiting/regurgitation, and chest pain were obtained. Esophageal function was evaluated initially by scintigraphy using liquid and semisolid bolus. Time-activity curves based on the mean condensed images were used to calculate residual activity at 100 s after swallowing. According to both scintigraphy and clinical evaluation results, participants underwent a radiological and manometric study. RESULTS: The most frequent symptoms in Down's syndrome patients were: dysphagia for liquids (n = 9), dysphagia for solids (n = 10), vomiting/regurgitation (n = 8), and chest pain (n = 2). Liquid and semisolid retention of the tracer was significantly higher in Down's syndrome patients than in controls (p < 0.05). In 15 participants with Down's syndrome, tracer retention was higher than the 95 percentile of controls' retention. No correlation was found between the global or individual symptom score and esophageal retention quantified by scintigraphy. Hypothyroidism was unrelated to esophageal symptoms or retention. Five of the 15 esophagograms performed were abnormal, showing barium retention and/or esophageal dilation. Manometry showed achalasia in two subjects, total body aperistalsis in one, and nonspecific esophageal motor disorder in two. CONCLUSION: Esophageal motor disorders, particularly achalasia, are frequent in individuals with Down's syndrome. Awareness of esophageal dysmotility in this population is important, even though symptoms are not evident, to avoid potential complications.

Adolescent↗
PubMed2001

Effects of the calcium release inhibitor dantrolene and the Ca2+-ATPase inhibitor thapsigargin on spinal nociception in rats.

The effects produced by the intrathecal administration of dantrolene and thapsigargin, measured in several analgesic tests in the rat are described. Dantrolene decreases the release of calcium from intracellular stores and thapsigargin is able to inhibit the reticular Ca2+-ATPase, avoiding intracellular calcium storage. Dantrolene (30-300 nmol/rat) and thapsigargin (3-30 nmol/rat) reduced the nociceptive behavior (biting, scratching, licking; BSL) produced by the NK(1) receptor agonist septide (0.5 microg), without affecting the BSL induced by AMPA (2 microg) or NMDA (4 microg). Also, both drugs elicited analgesia in the tail-flick test but not in the formalin test. The antinociceptive effects induced by thapsigargin were more intense and long-lasting than those produced by dantrolene. These results seem to indicate that the intracellular modulation of calcium homeostasis could be an interesting target in order to induce spinal analgesia.

Analgesics↗
PubMed2001

Roundabout signalling, cell contact and trophic support confine longitudinal glia and axons in the Drosophila CNS.

Contrary to our knowledge of the genetic control of midline crossing, the mechanisms that generate and maintain the longitudinal axon pathways of the Drosophila CNS are largely unknown. The longitudinal pathways are formed by ipsilateral pioneer axons and the longitudinal glia. The longitudinal glia dictate these axonal trajectories and provide trophic support to later projecting follower neurons. Follower interneuron axons cross the midline once and join these pathways to form the longitudinal connectives. Once on the contralateral side, longitudinal axons are repelled from recrossing the midline by the midline repulsive signal Slit and its axonal receptor Roundabout. We show that longitudinal glia also transiently express roundabout, which halts their ventral migration short of the midline. Once in contact with axons, glia cease to express roundabout and become dependent on neurons for their survival. Trophic support and cell-cell contact restrict glial movement and axonal trajectories. The significance of this relationship is revealed when neuron-glia interactions are disrupted by neuronal ablation or mutation in the glial cells missing gene, which eliminates glia, when axons and glia cross the midline despite continued midline repellent signalling.

Animals↗
PubMed2001

High prevalence of RET tyrosine kinase activation in Mexican patients with papillary thyroid carcinomas.

RET/PTC oncogene expression is restricted to papillary thyroid carcinomas (PTC). At least three forms of this oncogene have been described. These are generated by the rearrangement of the 5'-terminal region of different expressed genes with the tyrosine-kinase (TK) domain of the ret proto-oncogene. Several studies showing the correlation between the expression of this oncogene, clinical outcome, and histological subtypes have been published. Thirty-five paraffin-embedded PTC samples from patients without a history of radiation exposure were studied. Immunohistochemistry (IHC) and in situ hybridization (ISH) were used to determine a possible correlation between RET activation, clinical outcome, and tumor subtype. Almost half of the studied cases presented with tumoral extension or metastases. Ret gene transcripts and protein were found in all PTC variants as well as in their corresponding metastases. In contrast, none of the follicular adenomas, goiters, or normal follicular cells from the thyroid gland showed evidence of ret activation. We observed a high frequency of ret expression in PTCs, suggesting that ret activation is a common event in nonradiation-related PTC from Mexican patients.

Adult↗
PubMed2000

Mechanisms involved in kaempferol-induced relaxation in rat uterine smooth muscle.

The effect of kaempferol on KCI (60 mM)-induced tonic contraction in isolated rat uterus and its modification by inhibitors of cAMP-dependent protein kinase (PKA) (Rp-cAMPS and TPCK), phosphodiesterase (papaverine), adenylyl cyclase (2',3'-dideoxyadenosine, DDA), transcription (actinomycin D), protein synthesis (cycloheximide) and ornithine decarboxylase (alpha-difluoromethyl-ornithine, DFMO), as well as a polyamine, spermine, have been assayed. Kaempferol (3 to 60 microM) induced concentration-dependent relaxation on KCl-induced tonic contraction (IC50: 10.1 +/- 1.89 microM). This relaxing effect was antagonized (p<0.05) by Rp-cAMPS (10 microM), TPCK (3 microM), DDA (100 microM), actinomycin D (4 and 12 microM), cycloheximide (100 microM), DFMO (10 mM), actinomycin D (12 microM) plus TPCK and actinomycin D (12 microM) plus spermine (1 mM). Furthermore, the displacement obtained with actinomycin D plus DFMO was not statistically significant. Our results suggest that kaempferol through cAMP produces transcriptional events and polyamines are, at least partially, involved in the relaxant effect of kaempferol.

Adenylyl Cyclase Inhibitors↗
PubMed2000

Mechanism of mifepristone-induced spasmolytic effect on isolated rat uterus.

Mifepristone, a synthetic 19-norsteroid, relaxed the KCl-induced tonic contraction in isolated rat uterus in a concentration-dependent way and CaCl2 (0.1 to 10 mM) counteracted it. This effect was similar to other steroids although the mechanisms involved are unclear. Before adding the contracturant, tissue was incubated with actinomycin D (10 microM), cycloheximide (300 microM), TPCK (3 and 10 microM), Rp-cAMPS (30 microM), DDA (100 microM) and H-7 (1 microM). None of these modified the relaxing effect of mifepristone. Incubation with drugs that interfere with cGMP such as a nucleotide analogue DDG (100 microM), a soluble guanylyl cyclase inhibitor ODQ (1 microM) and an inhibitor of protein kinase G 8pCPTcGMPS (1 microM) significantly modified the effect of mifepristone, increasing its IC50.

Animals↗
PubMed2000

Differential expression of amiloride-sensitive Na+ channel subunits messenger RNA in the rat uterus.

The expression of the amiloride-sensitive Na+ channel was investigated by reverse transcription-polymerase chain reaction (RT-PCR) in uteri from pregnant and non-pregnant rats. Three subunits (alpha,beta,gamma) of this epithelial Na+ channel have been characterized in the rat. All three subunit mRNAs were present in day 16 pregnant uteri while only alpha and beta subunit mRNAs were detected in uteri from non-pregnant or day 1 postpartum rats. The level of expression of the alpha subunit was similar in day 16 pregnant and non-pregnant animals while the level of expression of the beta subunit was higher in pregnant than in non-pregnant rats. These findings show that amiloride-sensitive Na+ channels are expressed in the rat uterus and that mRNA expression levels of the alpha, beta and gamma subunits are selectively and differentially regulated during pregnancy in the rat.

Amiloride↗
PubMed2000

Mechanisms involved in UTP-induced contraction in isolated rat aorta.

The mechanisms of UTP-induced contractions in the rat aorta strips were studied. These were only partially inhibited in a Ca(2+)-free medium or by incubation with verapamil or nifedipine. Successive challenges did not decrease the magnitude of the contraction in the absence of external Ca(2+). Quin 2(acetoxymethyl) ester (Quin 2AM), 8-(N,N-diethylamino)octyl 3,4,5-trimetoxybenzoate (TMB-8), thapsigargin and ryanodine inhibited these contractions. The participation of protein kinase C is also very likely, since downregulation by the phorbol 12,13 dibutyrate (PDB) decreased UTP-induced contraction, and staurosporine and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) antagonized UTP-induced contractions and relaxed UTP-induced tonic contractions. Therefore, different pools of intracellular Ca(2+) and protein kinase C seem to participate in UTP-induced contraction and in the mechanisms of maintenance in a Ca(2+)-free medium.

Animals↗
PubMed2000

Intrathecal N-methyl-D-aspartate (NMDA) induces paradoxical analgesia in the tail-flick test in rats.

The intrathecal (IT) administration of NMDA in rodents has usually been reported to produce hyperalgesic reactions, although some articles describe that spinal NMDA can lead to analgesia. We show here that the nociceptive behavior (biting, scratching, licking; BSL) observed after NMDA injection (1-8 microg/rat; IT) is followed by a long period of increased tail-flick latencies, not longer detected 24 h after NMDA administration. The NMDA-receptor antagonist CPP (10-100 ng/rat; IT) blocked the BSL behavior induced by NMDA. In the tail-flick test, this antagonist induced analgesia by itself, and was able, at 30 ng/rat, to prevent the NMDA-mediated analgesia. The implication of opiate mechanisms was discarded since naloxone (3 and 10 mg/kg; IP) did not antagonize NMDA-induced analgesia. Finally, the involvement of the intracellular calcium binding protein calmodulin was assessed. The calmodulin inhibitor, calmidazolium (30-300 microg/rat; IT) only blocked the excitatory effect (BSL) without modifying the tail-flick analgesia produced by NMDA (4 microg). These results show that a single intrathecal administration of NMDA sequentially induces both nociceptive and antinociceptive, nonopiate responses in rats.

Analgesics, Non-Narcotic↗
PubMed2000

Human papilloma virus status and chromosomal imbalances in primary cervical carcinomas and tumour cell lines.

Human papilloma virus (HPV) infection is the crucial step in the initiation of cervical carcinomas. In addition, HPV18 has been implicated in tumour progression and adverse clinical outcome. We determined the HPV types in 12 primary cervical carcinomas and 12 cell lines and compared the findings with the comparative genetic hybridisation (CGH) pattern of chromosomal alterations. The most frequent alteration was the deletion at 3p14 followed by the loss of 2q34-q36 along with 3q gain. High risk HPV types were detected in all samples except one primary tumour. In contrast to the normal distribution, HPV18 was present in 75% of cases including all cell lines. The cell lines carried a higher number of genetic alterations and a different CGH pattern for several chromosomes than the primary tumours, despite microdissection. Purely HPV18 positive cases indicated a high incidence of imbalances at specific loci with peaks of the histogram coinciding with known HPV integration sites. The study suggests that HPV infection is associated with a recurrent pattern of chromosomal changes in cervical carcinomas and that the development and progression of these alterations is triggered by integration into the host genome.

Carcinoma, Squamous Cell↗
PubMed2000

Hydroxymethylfurfural and furosine reaction kinetics in tomato products.

The reaction kinetics of two heat damage indices, HMF and furosine, were examined in four tomato products with different dry matter contents (10.2, 25.5, 28.6, and 34.5%) over a temperature-time range of 80-120 degrees C and 0-255 min. The reactions followed pseudo-zero order kinetics. E(a) and z-value were, respectively, 139. 9 kJ/mol and 19.2 degrees C for HMF, and 93.9 kJ/mol and 28.4 degrees C for furosine. The analyses of both indices in several samples of commercial and industrial tomato products showed very low levels of HMF (from 1 to 42 ppm) and a lack of correlation between HMF and furosine mainly because of the different evolution of the two indices during storage. The HMF level of a tomato paste sample stored at 25 degrees C decreased from 609 to 17 ppm after 98 days, while furosine increased from 458 to 550 mg/100 g of protein.

Food Preservation↗
PubMed2000

Chromosomal imbalances in brain metastases of solid tumors.

Metastases account for approximately 50% of the malignant tumors in the brain. In order to identify structural alterations that are associated with tumor dissemination into the central nervous system we used Comparative Genomic Hybridization (CGH) to investigate 42 brain metastases and 3 primary tumors of 40 patients. The metastases originated from lung cancer (14 cases), melanomas (7), carcinomas of breast (5), colon (5), kidney (5), adrenal gland (1) and thyroid (1). In addition, tumors of initially unknown primaries were assessed in 3 cases. The highest incidence of DNA gains were observed for the chromosomal regions 1q23, 8q24, 17q24-q25, 20q13 (>80% of cases) followed by the gain on 7p12 (77%). DNA losses were slightly less frequent with 4q22, 4q26, 5q21, 9p21 being affected in at least 70% of the cases followed by deletions at 17p12, 4q32q34, 10q21, 10q23-q24 and 18q21-q22 in 67.5% of cases. Two unusual narrow regional peaks were observed for the gain on 17q24-q25 and loss on 17p12. The incidence at individual loci can be viewed at our CGH online tumor database at http:// amba.charite.de/cgh/. The metastases of each tumor type showed a recurrent pattern of changes. In those cases with primary tumor and metastases available, the CGH pattern exhibited a high degree of conformity. In conclusion, our data suggests that specific genetic lesions are associated with tumor dissemination into the nervous system and that CGH analysis may be a useful supplementary tool for classification of metastases with unknown origin.

Brain Neoplasms↗
PubMed2000

Glia maintain follower neuron survival during Drosophila CNS development.

While survival of CNS neurons appears to depend on multiple neuronal and non-neuronal factors, it remains largely unknown how neuronal survival is controlled during development. Here we show that glia regulate neuronal survival during formation of the Drosophila embryonic CNS. When glial function is impaired either by mutation of the glial cells missing gene, which transforms glia toward a neuronal fate, or by targeted genetic glial ablation, neuronal death is induced non-autonomously. Pioneer neurons, which establish the first longitudinal axon fascicles, are insensitive to glial depletion whereas the later extending follower neurons die. This differential requirement of neurons for glia is instructive in patterning and links control of cell number with axon guidance during CNS development.

Animals↗