Search PubMed⌕ Search

Biomedical subjects

M Gonzalez

Publications and source records attributed to M Gonzalez.

At least 73 records · Page 4Linked to original sources
PubMed2000

The role of CD40-CD154 interactions in the regulation of cell mediated immunity.

CD40 is expressed on a diverse array of cell types from the hematopoietic and non-hematopoietic compartments. Within the hematopoietic compartment, CD40 is found constitutively expressed on B cells, dendritic cells (DC) and macrophages. The function of CD40 in B cells has been documented as being essential in the control of humoral immunity. In DCs and macrophages, CD40 has been shown to be important in the induction of antigen-presenting cell (APC) maturation and effector function. CD40 is also expressed on non-hematopoietic cells like keratinocytes, epithelial cells, and vascular endothelial cells and has been shown to be functionally important on these cell types.

Animals↗
PubMed2000

Behavioural motor effects of MK-801 and DNQX parenteral administration in adult cats: dose-response analysis. Modulatory role of dopaminergic D1 and D2 antagonists on MK-801 induced motor behaviours.

1. Administration of MK-801 a selective antagonist of the NMDA receptors (50, 100 and 150 micrograms/kg, s.c.) elicited in adult cats ataxia and loss of equilibrium. A dose-response effect was observed. 2. Administration of DNQX, a selective antagonist of the non-NMDA receptors, even with doses 20 times higher than those employed with MK-801, did not produce any behavioural disturbances. 3. Previous injection of SCH 23390, a selective parenteral antagonist of dopamine D1 receptor, reduced significantly the intense ataxic effects of MK-801, while sulpiride only increased the latency of the symptoms. 4. The results are discussed considering the reported interactions between the dopaminergic and glutamatergic systems.

Animals↗
PubMed1999

Gap junctional coupling and patterns of connexin expression among neonatal rat lumbar spinal motor neurons.

Interneuronal gap junctional coupling is a hallmark of neural development whose functional significance is poorly understood. We have characterized the extent of electrical coupling and dye coupling and patterns of gap junction protein expression in lumbar spinal motor neurons of neonatal rats. Intracellular recordings showed that neonatal motor neurons are transiently electrically coupled and that electrical coupling is reversibly abolished by halothane, a gap junction blocker. Iontophoretic injection of Neurobiotin, a low molecular weight compound that passes across most gap junctions, into single motor neurons resulted in clusters of many labeled motor neurons at postnatal day 0 (P0)-P2, and single labeled motor neurons after P7. The compact distribution of dye-labeled motor neurons suggested that, after birth, gap junctional coupling is spatially restricted. RT-PCR, in situ hybridization, and immunostaining showed that motor neurons express five connexins, Cx36, Cx37, Cx40, Cx43, and Cx45, a repertoire distinct from that expressed by other neurons or glia. Although all five connexins are widely expressed among motor neurons in embryonic and neonatal life, Cx36, Cx37, and Cx43 continue to be expressed in many adult motor neurons, and expression of Cx45, and in particular Cx40, decreases after birth. The disappearance of electrical and dye coupling despite the persistent expression of several gap junction proteins suggests that gap junctional communication among motor neurons may be modulated by mechanisms that affect gap junction assembly, permeability, or open state.

Animals↗
PubMed1999

Splenogonadal fusion limb defect syndrome: report of five new cases and review.

Splenogonadal fusion (SGF) is a rare congenital malformation in which the spleen is abnormally connected to the gonad. SGF may occur as an isolated condition or may be associated with other malformations, especially with terminal limb defects in what is called splenogonadal fusion limb defect (SGFLD) syndrome. In this article, we report on 5 new cases of SGFLD and we review the 25 cases reported since 1889. Most cases reviewed here have a combination of severe limb and oro-mandibular defects, suggesting that SGFLD may be related to the broader group of Hanhart complex. In addition, several cases have limb malformations and facial anomalies, which suggest that SGFLD overlaps with both femur-fibula-ulna dysostosis and femoral-facial syndrome. The hypothesis of a vascular disruptive event, occurring between the 5th and the 7th weeks of gestation, could explain the limb defects, the mandibular hypoplasia, and the fusion of the spleen to the gonad observed in SGFLD. However, this heterogenous and polytopic condition could also be the consequence of a primary field defect. All the cases to date reported have been sporadic and the recurrence risk is probably low. However, a recent case of Roberts syndrome with SGF was reported that suggests careful examination of chromosomal status.

Abnormalities, Multiple↗
PubMed1999

Cutting edge: sustained expansion of CD8+ T cells requires CD154 expression by Th cells in acute graft versus host disease.

Brief treatment with alphaCD154 Ab has been shown to prevent acute graft versus host disease (aGvHD). We extend these data to show that in the absence of CD154 function, donor T cells are unable to expand or generate high level anti-host CTL activity. Using transgenic (Tg) alloreactive CD8+ T cells adoptively transferred into allogeneic recipients, we show that short-term expansion of the CD8+ Tg T cells occurred in the absence of Th cells, and this short-term expansion could be facilitated with an agonistic alphaCD40. While CD40 agonism could enhance short-term expansion, sustained expansion of CD8+ Tg T cells required bona fide CD154-expressing CD4+ alloreactive Th cells. While CD154 was necessary for CD8+ Tg T cell sustained expansion, IL-2 was also implicated as essential. These observations suggest alphaCD154 therapy in GvHD is effective because the treatment causes an abortive CD8 alloresponse leading to the exhaustion or deletion of alloreactive CD8+ clones preventing the development of disease.

Acute Disease↗
PubMed1999

Lack of efficacy of oral bovine type II collagen added to existing therapy in rheumatoid arthritis.

OBJECTIVE: To investigate the efficacy of oral type II collagen (CII) in the treatment of rheumatoid arthritis (RA), when added to existing therapy. METHODS: Patients with active RA (n = 190) were randomized into a 6-month, double-blind, placebo-controlled trial. Patients continued to take their current arthritis medications. Patients received either placebo or bovine CII, 0.1 mg/day for 1 month, then 0.5 mg/day for 5 months. RESULTS: There were no significant differences between the baseline characteristics of either group. The primary response parameter was the American College of Rheumatology (ACR) preliminary definition of improvement in RA (ACR 20). There was no statistically significant difference in the ACR 20 after 6 months (20.0% of placebo patients; 16.84% of bovine CII patients). There were significant differences in several clinical variables after treatment, all favoring the placebo group. CONCLUSION: Oral solubilized bovine CII, added to existing therapy, did not improve disease activity in patients with RA.

Administration, Oral↗
PubMed1999

Immune complex size and complement regulate cytokine production by peripheral blood mononuclear cells.

We have previously shown that immune complexes isolated from children with juvenile rheumatoid arthritis are heterogeneous in their size, composition, and proinflammatory capacities. The experiments described here were undertaken to clarify further the roles of size and composition in determining the proinflammatory effects of immune complexes. We incubated peripheral blood mononuclear cells (PBMCs) with different soluble immune complex preparations: opsonized complexes, which were formed in the presence of serum, unopsonized complexes, which were formed in the absence of serum, and immune precipitates solubilized by complement after their formation. ELISA assays showed that immune complexes formed in the presence of complement were less efficient than unopsonized complexes in inducing IL-1beta and IL-8 secretion from leukocytes. Solubilized immune precipitates showed intermediate capacity to stimulate the release of both cytokines. Complexes formed in heat-inactivated serum were as efficient as unopsonized complexes in eliciting cytokine secretion from the cells. The capacity of complement to regulate cytokine secretion from leukocytes was related, at least in part, to immune complex size. Sucrose density gradients showed unopsonized complexes and solubilized immune precipitates were larger than opsonized immune complexes. In contrast, fluid-phase binding of C4 to immune complexes, which did not appreciably change immune complex size, substantially increased IL-1beta secretion from PBMC.

Antigen-Antibody Complex↗
PubMed1999

[Human "pancreatic" bladder. Two case reports].

The aim of this study is to report two similar cases with an "accessory biliary duct" confluent to the main pancreatic duct. There was pancreatic juice inside the "gallbladder". There was no connection between "accessory biliary duct" and intra or extrahepatic biliary ducts. This anomalous junction of the "cystic duct" and the main pancreatic duct may be explained by embryology. These two cases could be the first human "pancreatic" bladders reported.

Bile Ducts↗
PubMed1999

Lung transplantation from ventilated non-heart-beating donors: experimental study in a neonatal swine model.

BACKGROUND/PURPOSE: A shortage of transplantable lungs is a constant and frustrating reality. The use of organs retrieved from ventilated non-heart-beating donors (VNHBD) may alleviate this problem. The purpose of this work was to assess lung function of donor grafts subjected to different time lengths of in situ warm ischemia (WIT). METHODS: Twenty piglets weighing between 6 and 8 kg were allocated randomly to the following study groups: Sham (n = 5), heart-beating donors, non warm ischemia; I-30 (n = 5), I-60 (n = 5) and I-90 (n = 5), VNHBD-WIT of 30, 60, and 90 minutes, respectively. Recipients were rendered dependent on the single left transplanted lung by clamping right pulmonary artery and bronchus 1 hour after transplantation. Assessment of pulmonary function was monitored hourly by hemodynamic, oxygenation, and pulmonary mechanic measurements during a period of 6 hours after reperfusion. Lung grafts were weighed pre- and posttransplantation. RESULTS: Final mean lung weight was significantly greater in VNHBD (92.5+/-3.1 v Sham values 75.6 g+/-2.4; P < .01). Cold ischemic time averaged 80.1+/-2.7 minutes. After right lung exclusion, hemodynamic changes consisted of a sustained increase in pulmonary vascular resistance and a reduction in cardiac output. Lung mechanics also deteriorated with a gradual rise in airway resistance and a fall in compliance. CONCLUSIONS: These data suggest that posttransplantation lung graft function from VNHBD with up to 90 minutes of WIT, is preserved and equivalent to those achieved by grafts harvested after heart-beating donation.

Analysis of Variance↗
PubMed1999

Intraoral widening and lengthening of the mandible in baboons by distraction osteogenesis.

PURPOSE: The purpose of this study was to analyze the skeletal and dental positional changes and histomorphology of the distraction regenerates and mucogingival periosteal tissues that occurred after simultaneous widening and bilateral lengthening of the mandible in baboons by a miniaturized intraoral bone-borne distraction appliance. MATERIALS AND METHODS: Distraction appliances were activated 5 days after vertical ramus and symphyseal osteotomies at a rate of 0.9 mm/d for 10 days. The appliances were then stabilized for 8 weeks, after which the animals were killed. The distraction gaps and gingival tissues were analyzed clinically, histologically, and by standardized radiographic studies. RESULTS: Positional changes of the canines and incisor apices were proportional to the skeletal movements. Tipping of both incisors toward the center of the distraction gap was observed. Proportionate movement of the superior and inferior portion of the distracted segments was noted. Newly formed longitudinal trabecular columns parallel to the vector of distraction originated from the intact margins of alveolar bone contiguous with the adjacent teeth. Active histogenesis occurred in the stretched mucogingival periosteal tissues located in the distraction gaps. CONCLUSIONS: The results of this investigation support the clinical use of the miniaturized intraoral bone-borne distraction appliance to selectively widen and lengthen the mandible. The orientation of the mandibular distractors must be parallel to the common vector of distraction, which should be parallel to the maxillary occlusal plane. The formation of a bone regenerate in the alveolar region depends on the presence of an adequate bone interface on either side of the distraction gap.

Alveolar Process↗
PubMed1999

Disruption of Trkb-mediated signaling induces disassembly of postsynaptic receptor clusters at neuromuscular junctions.

Neurotrophins and tyrosine receptor kinase (Trk) receptors are expressed in skeletal muscle, but it is unclear what functional role Trk-mediated signaling plays during postnatal life. Full-length TrkB (trkB.FL) as well as truncated TrkB (trkB.t1) were found to be localized primarily to the postsynaptic acetylcholine receptor- (AChR-) rich membrane at neuromuscular junctions. In vivo, dominant-negative manipulation of TrkB signaling using adenovirus to overexpress trkB.t1 in mouse sternomastoid muscle fibers resulted in the disassembly of postsynaptic AChR clusters at neuromuscular junctions, similar to that observed in mutant trkB+/- mice. When TrkB-mediated signaling was disrupted in cultured myotubes in the absence of motor nerve terminals and Schwann cells, agrin-induced AChR clusters were also disassembled. These results demonstrate a novel role for neurotrophin signaling through TrkB receptors on muscle fibers in the ongoing maintenance of postsynaptic AChR regions.

Adenoviridae↗
PubMed1999

Monitoring of CD34+ cells during leukapheresis allows a single, successful collection of hemopoietic progenitors in patients with low numbers of circulating stem cells.

We have studied a total of 188 patients with hematological malignancies, submitted to mobilization therapy with G-CSF associated or not with chemotherapy in order to: (1) establish the lower limit of circulating progenitor cells that allows the collection of 2 x 10(6) CD34+ cells/kg by a single leukapheresis, utilizing the instrument set on standard parameters; (2) evaluate whether the number and quality of CD34+ cells collected remain stable during leukapheresis; and (3) collect a sufficient number of circulating CD34+ cells by a single procedure in patients in whom such an approach would have been insufficient to reach the target with the instrument set on standard parameters. The retrospective analysis conducted in 85 patients showed that 19 circulating CD34+ cells/microl represented the cut-off number capable of discriminating between patients who will require one or more apheresis to collect 2 x 10(6) CD34+ cells/kg. The validity of this value was prospectively confirmed in 70 subsequent patients. Based on in vitro results that showed the stability in the number of CD34+ cells, the proportion of different CD34+ cell subpopulations and the clonogenic capacity of the stem cell compartment during leukapheresis both in the blood of the patients and in samples taken directly from the instrument, we have adapted the blood volume to be processed in 33 patients with <19 PB CD34+ cells/microl. Stem cell collection was monitored during the leukapheresis and the procedure was prolonged for a time period estimated to be sufficient to reach the target number of CD34+ cells with a single procedure. The median increment of the total blood volume processed, calculated from the volume set automatically by the instrument was 25.2%, with a median of 3.3-fold total blood volume processed. In all cases, a sufficient CD34+ cell collection was completed in a single procedure. After autograft, the pattern of blood reconstitution was similar to that of all the other patients.

Adolescent↗
PubMed1999

Clinical significance of CD34+ cell dose in long-term engraftment following autologous peripheral blood stem cell transplantation.

The number of CD34+ cells has been described as the best parameter for predicting the quality of engraftment in peripheral blood progenitor cell (PBPC) transplantation in the early post-transplant period. In this study we have determined the optimal number of CD34+cells in order to maintain engraftment in the long term in a series of 100 patients receiving autologous PBPC transplantation. Based on our previous experience on the speed of early hematopoietic recovery, four subgroups of patients were established: patients infused less than 0.75 x 106/kg CD34+ (n = 9), 0.75 to 1.25 (n = 24), 1.25 to 2.0 (n = 37) and more than 2.0 (n = 30). These groups were designated as low, intermediate-low, intermediate-high and high CD34 groups, respectively. Transitory loss of neutrophil engraftment was observed in 67%, 30%, 16% and 6% of patients in the four mentioned CD34 groups respectively, with statistically significant differences between the different groups. Significant differences were also observed between the low CD34 group and the rest of the groups as regards platelet and red blood cell transfusion requirements, fever episodes, days of hospitalization and antibiotic requirements throughout the first year. Our results show that the dose of CD34+ cells influences engraftment also in the late post-transplant period, and correlates with transfusion and antibiotic requirements, fever episodes and days of hospitalization during the first year post-transplant.

Anti-Bacterial Agents↗
PubMed1999

Primers and protocols for standardized detection of minimal residual disease in acute lymphoblastic leukemia using immunoglobulin and T cell receptor gene rearrangements and TAL1 deletions as PCR targets: report of the BIOMED-1 CONCERTED ACTION: investigation of minimal residual disease in acute leukemia.

It is now widely accepted that the detection of minimal residual disease (MRD) has prognostic value in acute leukemia. However clinical MRD studies need standardized techniques. Therefore, several European laboratories have aligned their goals and performed comparative studies to achieve optimization and standardization of MRD techniques. This was achieved via the BIOMED-1 Concerted Action "Investigation of minimal residual disease in acute leukemia: International standardization and clinical evaluation." This report describes the development of PCR primers and protocols for the detection of MRD in acute lymphoblastic leukemia (ALL) using clone-specific junctional regions of immunoglobulin and T cell receptor gene rearrangements and TAL1 deletions as PCR targets. A total of 54 primers was developed (1) to amplify rearrangements of the TCRD, TCRG, and IGK (Kde) genes as well as TAL1 deletions; (2) to sequence the junctional regions and breakpoint fusion regions; and (3) to perform MRD detection in bone marrow or peripheral blood samples during follow-up of ALL patients. Protocols were established to identify PCR targets at diagnosis by performing 25 PCR reactions per patient using appropriate positive and negative controls. Standardized protocols were developed for MRD monitoring via single amplification of the PCR target followed by dot blot hybridization with the corresponding patient-specific junctional region probe. In addition, alternative approaches were designed for cases where the target sensitivity of at least 10(-4) was not obtained. The standardization described here of MRD-PCR techniques is essential for the process of translating MRD research into clinical practice.

Base Sequence↗