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Biomedical subjects

J Romero

Publications and source records attributed to J Romero.

At least 109 records · Page 6Linked to original sources
PubMed1998

Comparison of in vitro effects of triflusal and acetysalicylic acid on nitric oxide synthesis by human neutrophils.

Recent studies have suggested that the protective anti-ischemic effects of acetylsalicylic acid are stronger than the inhibition of platelet thromboxane A2 synthesis. Since ischemic events still occur in acetylsalicylic acid-treated patients, the development of new drugs with more powerful protective effects is needed. We compared the effects of a new platelet antiaggregating drug, 2-acetoxy-4-trifluoromethyl-benzoic acid (triflusal) and of acetylsalicylic acid on the interaction between human neutrophils and platelets, examining the capability of neutrophils to generate nitric oxide (NO). Triflusal, in the presence of neutrophils, showed a greater antiplatelet potency than acetylsalicylic acid to inhibit thrombin-induced platelet activation. Significant stimulation of NO-mediated mechanisms in the presence of acetylsalicylic acid or triflusal was demonstrated by the following findings: (1) increased metabolism of arginine to citrulline, (2) increase of cGMP in the platelet/neutrophil system and (3) the inhibitory action of the L-arginine (L-Arg) competitive analogue, NG-nitro-L-arginine-methyl ester (L-NAME), which was reversed by L-Arg. Triflusal increased the stimulation of NO synthesis by neutrophils more than did of acetylsalicylic acid. The main metabolite of triflusal, 2-hydroxy-4-trifluoromethylbenzoic acid (HTB), alone or in combination with acetylsalicylic acid, did not modify NO production by neutrophils. Therefore, the whole molecule of triflusal is needed to stimulate NO production by neutrophils. Our results show that, in the presence of neutrophils, triflusal exerts an antiplatelet effect greater than that of acetylsalicylic acid, demonstrating a more powerful stimulation of the NO/cGMP system. The present results indicate that it is possible to develop new and more potent acetylsalicylic acid-related antiplatelet drugs for the prevention of the myocardial ischemic/reperfusion processes.

Aspirin↗
PubMed1998

Time-course of the cannabinoid receptor down-regulation in the adult rat brain caused by repeated exposure to delta9-tetrahydrocannabinol.

Recent studies have demonstrated that the pharmacological tolerance observed after prolonged exposure to plant or synthetic cannabinoids in adult individuals seems to have a pharmacodynamic rather than pharmacokinetic basis, because down-regulation of cannabinoid receptors was assessed in the brain of cannabinoid-tolerant rats. In the present study, we have examined the time-course of cannabinoid receptor down-regulation by analyzing cannabinoid receptor binding, using autoradiography, and mRNA expression, using in situ hybridization, in several brain structures of male adult rats daily exposed to delta9-tetrahydrocannabinol (delta9-THC) for 1, 3, 7, or 14 days. With only the exception of a few number of areas, most of the brain regions exhibited a progressive decrease in cannabinoid receptor binding. Two facts deserve to be mentioned. First, the pattern of this down-regulation process presented significant regional differences in terms of onset of the decrease and magnitude reached. Second, the loss of cannabinoid receptor binding was usually accompanied by no changes in its mRNA expression. Thus, some structures, such as most of the subfields of the Ammon's horn and the dentate gyrus in the hippocampus, exhibited a rapid (it appeared after the first injection) and marked (it reached approximately 30% of decrease after 14 days) reduction of cannabinoid receptor binding as a consequence of the daily delta9-THC administration. However, no changes occurred in mRNA levels. Decreased binding was also found in most of the basal ganglia, but the onset of this reduction was slow in the lateral caudate-putamen and the substantia nigra (it needed at least three days of daily delta9-THC administration), and, in particular, in the globus pallidus (more than 3 days). The magnitude of the decrease in binding was also more moderate, with maximal reductions always less than 28%. No changes were seen in the entopeduncular nucleus and only a trend in the medial caudate-putamen. However, the decrease in binding in some basal ganglia was, in this case, accompanied by a decrease in mRNA levels in the lateral caudate-putamen, but this appeared after 7 days of daily delta9-THC administration and, hence, after the onset of binding decrease. In the limbic structures, cannabinoid receptor binding decreased in the septum nuclei (it needed at least 3 days of daily delta9-THC administration), tended to diminish in the nucleus accumbens and was unaltered in the basolateral amygdaloid nucleus, with no changes in mRNA levels in these last two regions. Binding also decreased in the superficial and deep layers of the cerebral cortex, but only accompanied by trends in mRNA expression. The decrease in binding was initiated promptly in the deep layer (after the first injection) and it reached more than 30% of reduction after 14 days of daily delta9-THC administration, whereas, in the superficial layer, it needed more than 3 days of daily delta9-THC administration and reached less than 30% of reduction. Finally, no changes in binding and mRNA levels were found in the ventromedial hypothalamic nucleus. In summary, the daily administration of delta9-THC resulted in a progressive decrease in cannabinoid receptor binding in most of the brain areas studied, and it was a fact that always occurred before the changes in mRNA expression in those areas where these existed. The onset of the decrease in binding exhibited regional differences with areas, such as most of the hippocampal structures and the deep layer of the cerebral cortex, where the decrease occurred after the first administration. Other structures, however, needed at least 3 days or more to initiate receptor binding decrease. Two structures, the entopeduncular nucleus and the ventromedial hypothalamic nucleus, were unresponsive to chronic delta9-THC administration, whereas others, the medial caudate-putamen and the basolateral amygdaloid nucleus, only exhibited trends.

Animals↗
PubMed1998

Diagnostic imaging of lipoma arborescens.

OBJECTIVE: The imaging characteristics of lipoma arborescens using plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) are described. DESIGN AND PATIENTS: Five patients with a diagnosis of lipoma arborescens are presented. Three had monoarticular involvement of the knee joint. In the remaining two patients both knees and both hips, respectively, were affected. All patients were examined using plain radiographs and MRI. CT was employed in two cases. RESULTS AND CONCLUSIONS: A conclusive diagnosis with exclusion of other synovial pathologies having similar clinical and radiological behavior can be achieved on the basis of the MRI characteristics of lipoma arborescens. The aetiology of lipoma arborescens remains unknown, but its association with previous pathology of the affected joints in all our patients supports the theory of a non-neoplastic reactive process involving the synovial membrane.

Adult↗
PubMed1998

Havana tomato virus, a new bipartite geminivirus infecting tomatoes in Cuba.

The cloning and nucleotide sequence of a new bipartite geminivirus found in Cuba is described. DNA A (2620 nt) and DNA B (2586 nt) presented a genomic structure resembling that of other geminiviruses transmitted by Bemisia tabaci. Both components had a common region of 168 nt with a 95% identity. Typical elements involved in replication and transcription were found in this region, though group-characteristic arrangement of iterons was not conserved in this virus. Sequence was compared with geminivirus sequences deposited in the GenBank. Interestingly, when total DNAs or individual ORFs and deduced amino acid sequences were compared, the highest scores were for different viruses. It showed to be most closely related to tomato mottle virus (81.9% and 65.5% similarity with DNAs A and B, respectively) and a member of the abutilon mosaic cluster of New World Begomoviruses. When clones A and B were co-agroinoculated they resulted highly infectious and induced symptoms in Nicotiana benthamiana plants. The A component alone was infectious but induced only mild symptoms, while the B component was not infectious. The presence of viral DNA in N. benthamiana plants was confirmed by dot-blot hybridization using specific probes. These data show that the cuban isolate is a new geminivirus for which the name of Havana tomato virus is proposed.

Base Sequence↗
PubMed1998

A repeatable alignment method and local coordinate description for knee joint testing and kinematic measurement.

A method for aligning cadaver knee specimens to a mechanical testing rig and determining local anatomical coordinate systems using landmarks identifiable on plane X-rays is introduced. Three sequential rotational alignments arc used to position the femur and tibia relative to the coordinate system of the testing mechanism. To validate this methodology five independent observers aligned the same knee specimen. The maximum error in the alignment orientations of the tibia and femur was 2.2 from the mean. These small misalignments produced variations of up to 4.7 in tibio-femoral rotations measured during knee flexion. Kinematic measurements of 15 specimens aligned using this procedure indicate that knee alignment is reproducible and physiologically relevant.

Biomechanical Phenomena↗
PubMed1998

The activation of cannabinoid receptors in striatonigral GABAergic neurons inhibited GABA uptake.

Cannabinoid receptors (CNRs) in basal ganglia are located on striatal efferent neurons which are gamma-aminobutiric acid (GABA)-containing neurons. Recently, we have demonstrated that CN-induced motor inhibition is reversed by GABA-B, but not GABA-A, receptor antagonists, presumably indicating that the activation of CNRs in striatal outflow nuclei, mainly in the substantia nigra, should be followed by an increase of GABA concentrations into the synaptic cleft of GABA-B receptor synapses. The present study was designed to examine whether this was originated by increasing GABA synthesis and/or release or by decreasing GABA uptake. We analyzed: (i) GABA synthesis, by measuring the activity of glutamic acid decarboxylase (GAD) and GABA contents in brain regions that contain striatonigral GABAergic neurons, after in vivo administration of CNs and/or the CNR antagonist SR141716; (ii) [3H]GABA release in vitro in the presence or the absence of a synthetic CN agonist, HU-210, by using perifusion of small fragments of substantia nigra; and (iii) [3H]GABA uptake in vitro in the presence or the absence of WIN-55,212-2, by using synaptosomes obtained from either globus pallidus or substantia nigra. Results were as follows. Delta9-tetrahydrocannabinol (delta9-THC) and HU-210, did not alter neither GAD activity nor GABA contents in both the striatum and the ventral midbrain at any of the two times tested, thus suggesting that CNs apparently failed to change GABA synthesis in striatonigral GABAergic neurons. A similar lack of effect of HU-210 on in vitro [3H]GABA release, both basal and K+-evoked, was seen when this CN was added to perifused substantia nigra fragments, also suggesting no changes at the level of GABA release. However, when synaptosome preparations obtained from the substantia nigra were incubated in the presence of WIN-55,212-2, a decrease in [3H]GABA uptake could be measured. This lowering effect was specific of striatonigral GABAergic neurons since it was not observed in synaptosome preparations obtained from the globus pallidus. In summary, the activation of CNRs located on striatonigral GABAergic neurons, which primarily access to GABA-B receptor synapses, was accompanied by a reduction in neurotransmitter uptake, thus prolonging the presence of GABA into the synaptic cleft. This mechanism might underly the CN-induced motor inhibition through the potentiation of the inhibitory effect of GABA on neuronal activity, in particular of nigrostriatal dopaminergic neurons.

Animals↗
PubMed1998

Cannabinoid receptor binding did not vary in several hypothalamic nuclei after hypothalamic deafferentation.

Cannabinoid receptors are sparsely distributed in the hypothalamic nuclei, although they seem to be located on key neurons because their activation produces important neuroendocrine effects. In the present study, we have examined whether cannabinoid receptor-containing hypothalamic neurons are intrinsic or extrinsic to this brain region. To this end, we have examined whether the hypothalamic deafferentation was followed by a general loss of cannabinoid receptor binding, thus suggesting that cannabinoid receptor-containing neurons would have their cell bodies outside the hypothalamus, or whether this was followed by no changes in binding, thus suggesting that cannabinoid receptors would be located on intrinsic neurons. Three experimental groups were then analyzed: (i) animals with complete hypothalamic deafferentation in both sides; (ii) hemideafferentated animals; and (iii) sham-operated animals. In the three cases, cannabinoid receptor binding did not vary among these three groups in any of the hypothalamic nuclei analyzed. These were the arcuate nucleus, ventromedial hypothalamic nucleus, lateral and dorsal hypothalamic areas, paraventricular nucleus and medial preoptic area. This clearly supports the view that cannabinoid receptor-containing neurons into the hypothalamus are all intrinsic to this brain region.

Animals↗
PubMed1998

[Thrombosis and coronary disease: neutrophils, nitric oxide and aspirin].

In recent years, relevant changes have occurred in the knowledge of the cellular mechanisms regulating platelet aggregation and adhesion to the endothelial surface. In particular, major aspects of the interactions between platelets and endothelial cells and neutrophils have been clarified. These interactions involve not only thrombosis-promoting or thrombosis-inhibiting properties but also several aspects of the regulation of vascular function. A new concept has progressively emerged showing thrombosis as a multicellular event in which cell-to cell interactions between platelets, neutrophils, and endothelium regulate the size of a growing thrombus. In brief, there is consistent evidence showing that two vasodilating mediators produced by endothelial cells and neutrophils (nitric oxide and prostacyclin) have antiaggregating platelet effects. Platelet activation is particularly relevant in myocardial ischemia, and several pharmacological strategies have been devised to prevent intravascular platelet activation. Aspirin remains a keystone of these preventive and damage-limiting strategies. Current knowledge maintains that low doses of aspirin decrease in vivo platelet aggregation by a selective inhibitory effect on thromboxane A2 production by platelets with maintenance of prostacyclin production by the endothelium. We have recently focussed our research on the basis that the antiaggregating effect of aspirin could be explained not only by the above-mentioned effects on thromboxane A2 synthesis, but also through its action on neutrophils. Our in vitro and ex vivo studies have demonstrated that neutrophils enhance the antiaggregating effects of acetylsalicilic acid on platelets. We have shown that acetylsalicilic acid stimulates nitric oxide production on neutrophils inhibiting the aggregating effects of thrombin, ADP or epinephrine on platelets. the role of the neutrophils in ischemic events enhancing the tissue damage through the release of several proteases, reactive oxygen species and tumor necrosis factor-alpha has been extensively demonstrated. In an experimental model of acute ischemia/reperfusion in rabbits, we have shown that acetylsalicilic acid is able to enhance the nitric oxide production by neutrophils providing a potential mechanism for the beneficial action of aspirin in the myocardial infarction. Further research is needed to assess the mechanisms of the action of aspirin during the thrombotic phenomena and its effects on the different types of cells that compound the microvascular environment.

Aspirin↗
PubMed1998

Loss of cannabinoid receptor binding and messenger RNA levels and cannabinoid agonist-stimulated [35S]guanylyl-5'O-(thio)-triphosphate binding in the basal ganglia of aged rats.

Recent reports have demonstrated that cannabinoid receptor binding decreases in several neurodegenerative diseases related to extrapyramidal function. However, there is little evidence with regard to potential changes of these receptors during senescence. The present study was designed to determine the possible existence of ageing-induced changes in cannabinoid receptor binding and gene expression in extrapyramidal areas. To this end, we analysed cannabinoid receptor binding and basal and cannabinoid receptor agonist-stimulated [35S]guanylyl-5'-O-(gamma-thio)-triphosphate binding, by using autoradiography, and cannabinoid receptor messenger RNA levels, by using in situ hybridization, in slide-mounted brain sections obtained from young (three-month-old) and aged (>two-year-old) rats. Results were as follows. Aged rats exhibited a marked decrease in cannabinoid receptor binding in most of the basal ganglia, excepting the globus pallidus which had similar binding levels in both young and aged rats. The highest decreases were in the entopeduncular nucleus (-49.6%) and substantia nigra pars reticulata (-45.2%), whereas more moderate decreases were found in the lateral caudate putamen (-29%) and only a decremental trend in the medial caudate putamen (-13.1%). These decreases in cannabinoid receptor binding were paralleled by less marked increases in WIN 55212-2-stimulated [35S]guanylyl-5'-O-(gamma-thio)-triphosphate binding in these structures in aged rats (% of agonist stimulation: 189% in the substantia nigra; 29.4% in the lateral caudate putamen) as compared to young rats (296% and 53.2%, respectively). Contrarily, the percentage of agonist stimulation was similar in the globus pallidus, an area where cannabinoid receptor binding did not change during ageing, of aged (205.5%) and young (215.5%) rats. In addition, aged rats also exhibited significant reductions in the cannabinoid receptor messenger RNA levels in the medial (-14.3%) and, in particular, in the lateral (-29.4%) caudate putamen, the area where the cell bodies of cannabinoid receptor-containing neurons, projecting to the substantia nigra, entopeduncular nucleus and globus pallidus, are located. In summary, the synthesis and binding levels of cannabinoid receptors markedly dropped in different structures of the extrapyramidal system of aged rats. Since these receptors, located in the basal ganglia, seem to play a role in motor control, this loss of cannabinoid receptors might be related to the motor impairment which progressively appears during senescence.

Aging↗
PubMed1998

Localization of mRNA expression and activation of signal transduction mechanisms for cannabinoid receptor in rat brain during fetal development.

In the present work, we analyzed cannabinoid receptor mRNA expression, binding and activation of signal transduction mechanisms in the fetal rat brain or in cultures of fetal neuronal or glial cells. Cannabinoid receptor binding and mRNA expression were already measurable at GD14, but they were only located in discrete regions at GD16. Among these, the hippocampus, the cerebellum and the caudate-putamen area, three regions that contain a marked signal for both binding and mRNA in the adult brain. Significant levels of binding and, in particular, of mRNA transcripts were also detected at GD16 in the cerebral cortex, midbrain and brainstem. These structures contain relatively low levels of binding and mRNA in the adult brain, suggesting that cannabinoid receptor gene is transiently expressed in atypical areas during the fetal period. The signal for cannabinoid receptor mRNA in the hippocampus, caudate-putamen and cerebral cortex progressively increased from GD16 up to GD21. At GD18 and GD21, mRNA transcripts could be measured in discrete nuclei, such as septum nuclei, ventromedial hypothalamic nucleus and others. The cerebral cortex exhibited the highest mRNA levels at GD21, although this was not accompanied by a parallel increase in binding. An important aspect is that binding measured at these ages represent binding to functional receptors because their activation by WIN-55,212-2 increased [35S]GTPgammaS binding in the same areas. This increase was reversed by a specific antagonist, SR141716. The areas where the stimulation was more marked were the midbrain and brainstem. Using cell cultures, we have observed that cannabinoid receptor mRNA is present in cortical and hippocampal neuronal cells, but not in the glial cells. However, WIN-55,212-2 was capable of stimulating [35S]GTPgammaS binding in membrane fractions obtained from cortical glial cells and this stimulation was reversed by SR141716. This was not seen with hippocampal glial cell cultures, but occurred in hippocampal and cortical neurons. In addition, the activation of these receptors with Delta9-tetrahydrocannabinol significantly reduced forskolin-stimulated cAMP production in cortical neuronal or glial cell cultures and this effect was reversed by SR141716. In summary, we have detected cannabinoid receptor binding, mRNA expression and activation of signal transduction mechanisms in the fetal rat brain (GD14-GD21), which support the view that the system constituted by these receptors and their putative endogenous ligands might play a role in specific molecular events of the brain development. Of relevance is that binding and mRNA expression appear atypically distributed in the fetal brain as compared with the adult brain, even, that their presence in white-matter-enriched areas might presumably indicate their location in non-neuronal cells. These studies with cell cultures suggest that CB1 receptor subtype is located in neuronal cells obtained from fetal brain, although preliminary evidence is provided of the existence of another receptor subtype operative in glial cells obtained from the cerebral cortex.

Animals↗
PubMed1998

Cannabinoid receptor and WIN-55,212-2-stimulated [35S]GTP gamma S binding and cannabinoid receptor mRNA levels in the basal ganglia and the cerebellum of adult male rats chronically exposed to delta 9-tetrahydrocannabinol.

The inhibition of motor behavior in rodents caused by the exposure to plant or synthetic cannabinoids has been reported to develop tolerance after repeated exposure. This tolerance seems to have a pharmacodynamic basis, since downregulation of cannabinoid receptors in motor areas, basal ganglia and cerebellum, has been demonstrated in cannabinoid-tolerant rats. The present study was designed to further explore this previous evidence by analyzing simultaneously in several motor areas of delta 9-tetrahydrocannabinol- (delta 9-THC)-tolerant rats: 1. Cannabinoid receptor binding, by using [3H]WIN-55,212-2 autoradiography; 2. Cannabinoid receptor activation of signal transduction mechanisms, by using WIN-55,212-2-stimulated [35S]-guanylyl-5'-O-(gamma-thio)-triphosphate ([35S]-GTP gamma S) autoradiography; 3. Cannabinoid receptor mRNA expression, quantitated by in situ hybridization. Results were as follows. As expected, the exposure to delta 9-THC for 5 d resulted in a decrease of cannabinoid receptor binding in the molecular layer of the cerebellum, medial, and lateral caudate-putamen and, in particular, entopeduncular nucleus. We also found decreased cannabinoid receptor binding in the superficial and deep layers of the cerebral cortex, two regions used as a reference to test the specificity of changes observed in motor areas. There were only two brain regions, the globus pallidus and the substantia nigra, where the specific binding for cannabinoid receptors was unaltered after 5 d of a daily delta 9-THC administration. However, in the substantia nigra, the magnitude of WIN-55,212-2-stimulated [35S]-GTP gamma S binding was lesser in delta 9-THC-tolerant rats than controls, thus suggesting a possible specific change at the level of receptor coupling to GTP-binding proteins. This was not seen neither in the globus pallidus nor in the lateral caudate-putamen, where agonist stimulation produced similar [35S]-GTP gamma S binding levels in delta 9-THC-tolerant rats and controls. Finally, animals chronically exposed to delta 9-THC also exhibited a decrease in the levels of cannabinoid receptor mRNA in the medial and lateral caudate-putamen, but there were no changes in the cerebellum (granular layer) and cerebral cortex. In summary, the chronic exposure to delta 9-THC resulted in a decrease in cannabinoid receptor binding and mRNA levels in the caudate-putamen, where cell bodies of cannabinoid receptor-containing neurons in the basal ganglia are located. However, this decrease particularly affected the receptor binding levels in those neurons projecting to the entopeduncular nucleus, but not in those projecting to the globus pallidus and substantia nigra, although, in this last region, a specific decrease in the efficiency of receptor activation of signal transduction mechanisms was seen in delta 9-THC-tolerant rats. The chronic exposure to delta 9-THC also resulted in decreased cannabinoid receptor binding in the cerebellum, although without affecting mRNA expression.

Analgesics↗
PubMed1998

[Endothelial dysfunction: a global response].

The endothelium is a dynamic organ involved in the genesis and development of the cardiovascular diseases. Nitric oxide (NO) is one of the factors released from endothelium. NO is generated by endothelial cells through the activity of a constitutive nitric oxide synthase (cNOS). Smooth muscle cells generate NO by an inducible NOS isoform (iNOS). NO regulates vascular tone, different mechanisms involved in the interaction of blood cells to the vascular wall, the growth of smooth muscle cells and the matrix protein synthesis. The lack of an endothelium-dependent vasodilatory response has been defined as endothelial dysfunction. It has been demonstrated a reduced endothelium-dependent vasodilation response in hypertension, aging, atherosclerosis ... and in patients without evident coronary disease. Although the cNOS has been initially described as constitutive, in recent years it has been demonstrated that several pathophysiological stimuli such as hypoxia, chronic exercise, cytokines regulate its level of expression. Our laboratory has demonstrated that an endothelial cytosolic protein regulates the half-lives of eNOS mRNA. This endothelial cytosolic protein could be a target for specific drugs to prevent endothelial dysfunction.

Endothelium, Vascular↗
PubMed1998

Testicular sperm extraction and intracytoplasmic sperm injection: a chance of fertility in nonobstructive azoospermia.

PURPOSE: We evaluate the efficacy of testicular sperm extraction and results of intracytoplasmic sperm injection in cases of nonobstructive azoospermia. In addition, we define predictive parameters for successful testicular sperm extraction in these patients. MATERIALS AND METHODS: A total of 154 patients with nonobstructive azoospermia underwent multiple testicular biopsies to obtain testicular spermatozoa and for histopathological diagnosis. Results of testicular sperm extraction were related to suspected etiology of azoospermia, patient age, maximal testicular volume, serum follicle-stimulating hormone and histopathology. When testicular sperm extraction was successful, intracytoplasmic sperm injection was performed. RESULTS: Spermatozoa were obtained from 63 patients (41%). No potential predictive parameters precluded successful testicular sperm retrieval. Fertilization was achieved in 74 of 76 intracytoplasmic sperm injection cycles. Normal 2 pronuclear fertilization was observed in 55% of the intact oocytes after microinjection. Clinical pregnancies were achieved in 21 cases for a pregnancy rate of 28% per started cycle. There were 4 miscarriages and 11 live births from 9 deliveries. In addition, a set of twins died after birth because of prematurity. Seven pregnancies were ongoing. CONCLUSIONS: Men with nonobstructive azoospermia may have areas of preserved spermatogenesis in the testicles, and these spermatozoa can be retrieved for intracytoplasmic sperm injection. Although some clinical and histopathological parameters are associated with significantly different sperm recovery rates, it is not possible to predict with certainty the outcome of testicular sperm extraction in an individual patient. If testicular sperm extraction is successful, intracytoplasmic sperm injection offers the chance of pregnancy to these otherwise intractably infertile couples.

Adult↗
PubMed1998

[Dislocated proximal humerus fracture--results after stabilization with a double plate].

Between October 1995 und December 1997, 57 patients with displaced 2-, 3- and 4-part fractures of the proximal humerus were treated by open reduction and internal fixation with two one-third tubular plates which were applied to the anterior and lateral aspect of the proximal humerus. For the follow-up evaluation shoulder function was assessed in 38 patients after an average of 16.8 +/- 4.2 months using the Constant-score: 32% of the patients showed excellent, 37% good, 21% satisfactory, and 10% unsatisfactory results. The high stability of this technique allows intensive physiotherapy in the early post-operative period and early reintegration in activities of daily living.

Aged↗
PubMed1997

Introduction of p53 induces cell-cycle arrest in p53-deficient human medullary-thyroid-carcinoma cells.

The structural integrity of the p53 gene in a human thyroid-medullary-carcinoma-derived cell line has been studied. Analysis of high-molecular-weight DNA showed that the p53 locus is severely rearranged. PCR and single-strand conformation polymorphism analysis revealed that a large portion of the 5' end of the p53 gene is lost, while a region encompassing exons 8 and 9 is rearranged. As a consequence, no virtual expression of a p53-specific transcript is detected in mRNA from the medullary-carcinoma cell line. The absence of a p53 protein prompted us to analyze the biological effect of exogenous expression of this tumor-suppressor gene on cell growth and viability, introducing retroviral constructs carrying full-length human wild-type p53 cDNA. Contrary to what has been described for other cell types, including most thyroid-carcinoma cell lines of follicular origin, these experiments allowed us to establish clonal-cell populations which constitutively express p53. Cytometric analysis revealed G1-specific cell-cycle arrest, responsible for growth retardation in the transfected clones when compared with the parental cell line. However, medullary-thyroid-carcinoma cells expressing p53 are able to partially overcome the G1 block and progress through the cell cycle. In the search of the mechanism(s) involved in these processes, we describe the interaction of p53 with specific p21WAF1/Cip1 promoter sequences by gel-retardation assays.

Blotting, Southern↗
PubMed1997

Time course of the effects of different cannabimimetics on prolactin and gonadotrophin secretion: evidence for the presence of CB1 receptors in hypothalamic structures and their involvement in the effects of cannabimimetics.

Several reports have demonstrated that (-)-delta9-tetrahydrocannabinol (delta9-THC) and arachidonylethanolamide [anandamide (AEA)] were able to inhibit prolactin (PRL) secretion from the anterior pituitary gland in male rodents, whereas ovarian phase-dependent effects were seen in females. However, in most of these studies, the analysis of PRL levels was performed at times longer than 30 min after cannabinoid administration. In the present study, we examined the time course of the effects of three different cannabimimetics, delta9-THC, AEA, and AM356 (R-methanandamide), a more stable analog of AEA, on PRL and gonadotrophin secretion in male Wistar rats. In addition, we characterized the presence of cannabinoid receptors in hypothalamic structures related to neuroendocrine control and studied their potential involvement in the effects of cannabimimetics. We found that the three compounds decreased plasma luteinizing hormone (LH) levels, although only the effects of delta9-THC were statistically significant. The inhibitory effect was already apparent at 40 min after administration, but only in the case of delta9-THC did it persist up to 180 min after administration. No significant changes were seen in plasma follicle-stimulating hormone (FSH) levels after the administration of any of the three different cannabimimetics at any of the four times analyzed. Both AEA and AM356 produced a significant decrease in plasma PRL levels, which appeared at 20 min after administration and persisted up to 60 min, waning after this time. Interestingly, the time course of the effect of delta9-THC resembled that of AEA and AM356 only during the later part of the response, because delta9-THC produced a marked increase in plasma PRL levels at 20 min, no changes at 40 min and a decrease from 60 min up to 180 min. In additional experiments, we tried to elucidate which of these two phases observed after delta9-THC administration was mediated by the activation of cannabinoid receptors. These receptors are present in hypothalamic structures related to neuroendocrine control, with the highest densities in the arcuate nucleus (dorsal area) and the medial preoptic area, and the lowest in the lateral hypothalamic area, although none of these regions exhibited high densities for this receptor as compared with classical regions containing cannabinoid receptors, such as the basal ganglia. The activation of these receptors by delta9-THC seems to be involved in the inhibitory phase of the effect of this cannabinoid on PRL release, but not in the early stimulation; when these receptors were blocked with a specific antagonist, SR141716, the stimulation by delta9-THC was still observed, but the late inhibition was abolished. In summary, AEA and AM356 markedly decreased PRL release and slightly decreased LH secretion, with no changes on FSH release. delta9-THC also produced a marked inhibition of LH secretion, but its effects on PRL were biphasic with an early stimulation not mediated by the activation of cannabinoid receptors, followed by a late and cannabinoid receptor-mediated inhibition. Their site of action may well be the hypothalamic structures related to neuroendocrine control, which contain a small, but probably very active, population of cannabinoid receptors.

Animals↗
PubMed1997

Effect of 5' and 3' terminal sequences, overall length, and coding capacity on the accumulation of defective RNAs associated with broad bean mottle bromovirus in planta.

Broad bean mottle bromovirus (BBMV) was shown to accumulate RNA2-derived defective interfering (DI) RNAs [Romero et al., Virology 194, 576-584 (1993); Pogany et al., Virology 212, 574-586 (1995)]. In this work, we utilize three sets of BBMV RNA2-derived artificial DI RNA constructs to determine factors that affect the accumulation of defective RNAs in planta. One set of deletion constructs was used to localize sequences required for efficient accumulation within the 5' 883 nt and the 3' 387 nt of the DI RNAs. The second set had a gradually increasing size of 3' nested deletions to determine the minimal length required for efficient DI RNA accumulation. The smallest DI RNA still accumulating in plants was found to be 1712 nt long. The third set consisted of frameshift mutants which showed that at least 64.4% of BBMV DI RNA sequences must have the 5' portion of the 2a open reading frame to ensure efficient accumulation. The importance of these factors in the selection of DI RNAs is discussed.

Bromovirus↗