Application of the Zero-Order Reaction Rate Model and Transition State Theory to predict porous Ti6Al4V bending strength.

Porous Ti6Al4V samples were produced by microsphere sintering. The Zero-Order Reaction Rate Model and Transition State Theory were used to model the sintering process and to estimate the bending strength of the porous samples developed. The evolution of the surface area during the sintering process was used to obtain sintering parameters (sintering constant, activation energy, frequency factor, constant of activation and Gibbs energy of activation). These were then correlated with the bending strength in order to obtain a simple model with which to estimate the evolution of the bending strength of the samples when the sintering temperature and time are modified: σY=P+B·[lnT·t-ΔGa/R·T]. Although the sintering parameters were obtained only for the microsphere sizes analysed here, the strength of intermediate sizes could easily be estimated following this model.

Early detection of age-related memory deficits in individual mice.

To date, no consensus has been reached concerning the age of the earliest onset of age-related cognitive deficits in rodents. Our aim was to develop a behavioral model allowing early and individual detection of age-related cognitive impairments. We tested young (3 months), middle-aged (10 months) and aged (17 months) C57Bl/6 mice in the starmaze, a task allowing precise analysis of the search pattern of mice via standardized calculation of two navigation indices. We performed mouse-per-mouse analyses and compared each mouse's performance to a threshold based on young mice's performances. Using this method we identified impaired mice from the age of 10 months old. Their deficits were independent of any sensorimotor dysfunctions and were associated with an alteration of the maintenance of the hippocampal CA1 late-LTP. This study develops reliable methodology for early detection of age-related memory disorders and provides evidence that memory can decline in some individuals as early as from the age of 10 months.

[Values of GERMCIDE neuropsychological protocol in a sample of normal subjects]. / Valores del protocolo neuropsicológico GERMCIDE en una muestra de sujetos normales.

INTRODUCTION: The diagnosis of patients with cognitive deterioration or dementia requires a global approach in which the neuropsychological examination is a key piece. As part of the GERMCIDE study (Group for the Study and Multicenter Registry of Incident Cases of Dementia in Spain), a protocol was designed that included an assessment of the different cognitive functions that are most frequently altered in dementias (memory, orientation, speech, praxis, abstraction capacity and executive function). METHODS: In order to obtain data in normal subjects, this neuropsychological protocol was applied to a group of persons over 50 years without cognitive deterioration or dementia. RESULTS: A total of 103 subjects whose ages ranged from 50 to 95 years (mean: 73.5; SD: 9.3 years); 39 (37.9%) men and 64 (62.1%) women were studied. The mean score on the Mini-Mental State Examination (MMSE) was 27/30 (SD: 2.0). In the speech and praxis tests, 90% of the subjects obtained the maximum value, while performances were more unequal in memory, reasoning and programming. Mean score, standard deviation and distribution in percentages for each subtest are presented. CONCLUSIONS: The values obtained in this sample of normal subjects and their distribution in percentages may be very helpful to facilitate the interpretation of the findings of the neuropsychological examination with the GERMCIDE protocol in the general neurology clinic visits and also in the specialized visits in dementia.

Valores del protocolo neuropsicológico GERMCIDE en una muestra de sujetos normales / Values of GERMCIDE neuropsychological protocol in a sample of normal subjects

Introducción. El diagnóstico de los pacientes con deterioro cognitivo o demencia exige un enfoque global en el que la exploración neuropsicológica es una pieza clave. Como parte del estudio GERMCIDE (Grupo para el Estudio y Registro Multicéntrico de Casos Incidentes de Demencia en España) se diseñó un protocolo que incluye una valoración de las diferentes funciones cognitivas que con mayor frecuencia se alteran en las demencias (memoria, orientación, lenguaje, praxias, capacidad de abstracción y función ejecutiva). Métodos. Con el objetivo de obtener datos en sujetos normales este protocolo neuropsicológico se aplicó a un grupo de personas mayores de 50 años sin deterioro cognitivo ni demencia. Resultados. Se estudiaron 103 sujetos con edades comprendidas entre 50 y 95 años (media: 73,5; desviación estándar [DE]: '9,3 años); 39 (37,90J0) hombres y 64 (62,1 %) mujeres. La puntuación media en el Mini-Mental State Examination (MMSE) fue de 27/30 (DE: 2,0). En las pruebas de lenguaje y praxias el 900J0 de los sujetos obtuvieron el valor máximo, mientras que en memoria, razonamiento y programación los rendimientos fueron más dispares. Se presenta la puntuación media, DE y distribución en percentiles para cada subtest. Conclusiones. Los valores obtenidos en esta muestra de sujetos normales y su distribución en percentiles pueden ser de gran ayuda para facilitar la interpretación de los hallazgos de la exploración neuropsicológica con el protocolo GERMCIDE en las consultas de neurología general y también en las consultas especializadas en demencia

Introduction. The diagnosis of patients with cognitive deterioration or dementia requires a global approach in which the neuropsychological examination is a key piece. As part of the GERMCIDE study (Group for the Study and Multicenter Registry of Incident Cases of Dementia in Spain), a protocol was designed that included an assessment of the different cognitive functions that are most frequently altered in dementias (memory, orientation, speech, praxis, abstraction capacity and executive function). Methods. In order to obtain data in normal subjects, this neuropsychological protocol was applied to a group of persons over 50 years without cognitive deterioration or dementia. Results. A total of 103 subjects whose ages ranged from 50 to 95 years (mean: 73.5; SD: 9.3 years); 39 (37.9%) men and 64 (62.1%) women were studied. The mean score on the Mini-Mental State Examination (MMSE) was 27/30 (SD: 2.0). In the speech and praxis tests, 90% of the subjects obtained the maximum value, while performances were more unequal in memory, reasoning and programming. Mean score, standard deviation and distribution in percentages for each subtest are presented. Conclusions. The values obtained in this sample of normal subjects and their distribution in percentages may be very helpful to facilitate the interpretation of the findings of the neuropsychological examination with the GERMCIDE protocol in the general neurology clinic visits and also in the specialized visits in dementia

[Parascalene block for shoulder arthroscopic surgery]. / Bloqueo paraescalénico para cirugía artroscópica de hombro.

OBJECTIVE: To evaluate the effectiveness of a parascalene block of the brachial plexus as the single form of anesthesia for arthroscopic surgery on the shoulder and for postoperative analgesia. MATERIAL AND METHODS: A parascalene block was performed in 151 ASA I-III patients using a plumb-bob technique with the aid of nerve stimulation and with the needle entering at a point 3 cm cephalad to the clavicle and 0.5-1 cm lateral to (and outside) the sternocleidomastoid muscle. We recorded the success or not of blockade, the incidence of side effects, clinical course during and after surgery, and patient and surgeon satisfaction with the technique. RESULTS: A full block was achieved in all patients, although 19 (13%) requiered a second puncture. Midazolam was administered to 34 patients for anxiety and 48 required urapidil to normalize blood pressure. Complications (incidental blocks) were rare, transitory, and mild: 6 patients with Claude Bernard-Horner syndrome, 13 with dysphonia due to recurrent nerve blockade, and 1 with diaphragmatic paresis. Postoperative pain was practically nonexistent. Administration of diclofenac as indicated was sufficient for 91.2% of the patients. The remaining 8.8% needed top-up doses. Patients and surgeons assessed the block as excellent. CONCLUSION: The parascalene technique to provide a brachial plexus block is effective for arthroscopic shoulder surgery.

Forebrain-specific calcineurin knockout selectively impairs bidirectional synaptic plasticity and working/episodic-like memory.

Calcineurin is a calcium-dependent protein phosphatase that has been implicated in various aspects of synaptic plasticity. By using conditional gene-targeting techniques, we created mice in which calcineurin activity is disrupted specifically in the adult forebrain. At hippocampal Schaffer collateral-CA1 synapses, LTD was significantly diminished, and there was a significant shift in the LTD/LTP modification threshold in mutant mice. Strikingly, although performance was normal in hippocampus-dependent reference memory tasks, including contextual fear conditioning and the Morris water maze, the mutant mice were impaired in hippocampus-dependent working and episodic-like memory tasks, including the delayed matching-to-place task and the radial maze task. Our results define a critical role for calcineurin in bidirectional synaptic plasticity and suggest a novel mechanistic distinction between working/episodic-like memory and reference memory.

Transgenic mice with neuronal overexpression of bcl-2 gene present navigation disabilities in a water task.

In the CNS, Bcl-2 is an antiapoptotic gene involved in the regulation of neuronal death. Transgenic mice overexpressing the human gene Bcl-2 (Hu-bcl-2 mice) showed delayed acquisition in two tasks requiring them to find a hidden platform starting from either a random or a constant starting location. The same mice were not deficient in another task requiring them to find a visible platform suggesting that the delay observed was not due to motor, visual or motivational deficits in the water. The delay observed in Hu-bcl-2 mice was more important in the random starting test in which the allocentric demand for navigation was stronger. The results suggested that allocentric navigation is particularly sensitive to abnormal CNS maturation following the overexpression of the bcl-2 gene. The specific deficits (motor learning, fear-related behavior and allocentric navigation) observed in Hu-bcl-2 mice suggest that the regulation of developmental neuronal death is crucial for multisensorial learning and emotional behavior.

CA1-specific N-methyl-D-aspartate receptor knockout mice are deficient in solving a nonspatial transverse patterning task.

In both humans and animals, the hippocampus is critical to memory across modalities of information (e.g., spatial and nonspatial memory) and plays a critical role in the organization and flexible expression of memories. Recent studies have advanced our understanding of cellular basis of hippocampal function, showing that N-methyl-d-aspartate (NMDA) receptors in area CA1 are required in both the spatial and nonspatial domains of learning. Here we examined whether CA1 NMDA receptors are specifically required for the acquisition and flexible expression of nonspatial memory. Mice lacking CA1 NMDA receptors were impaired in solving a transverse patterning problem that required the simultaneous acquisition of three overlapping odor discriminations, and their impairment was related to an abnormal strategy by which they failed to adequately sample and compare the critical odor stimuli. By contrast, they performed normally, and used normal stimulus sampling strategies, in the concurrent learning of three nonoverlapping concurrent odor discriminations. These results suggest that CA1 NMDA receptors play a crucial role in the encoding and flexible expression of stimulus relations in nonspatial memory.

Hu-Bcl-2 transgenic mice with supernumerary neurons exhibit timing impairment in a complex motor task.

Programmed neuronal cell death is common during development, and is thought to be important in the elimination of errors in axonal projection, cell position and sculpting of neuronal circuits. However, the potential importance of programmed cell death for complex behaviour in the adult animal has never been addressed. We studied motor abilities in a strain of transgenic mice with neuronal overexpression of the human Bcl-2 protein, which have supernumerary neurons due to reduced developmental cell death. Our results show that these mice have a clear deficiency in fine timing of motor coordination without impairment of basic motor functions. This is the first indication that altered developmental cell death and the consequent neuronal surplus can impair complex behaviour in the adult animal.

Overexpression of a Hu-bcl-2 transgene in Lurcher mutant mice delays Purkinje cell death.

Cerebellar Purkinje cells in the heterozygous Lurcher mutant undergo cell autonomous degeneration beginning in the second week of postnatal development and becoming almost total around 30-45 days. The Lurcher mutation was recently identified as gain-of-function defect in the delta 2 glutamate receptor causing a constitutive current leak, suggesting that +/Lc Purkinje cells die by an excitotoxic mechanism. In previous studies we have shown that overexpression of bcl-2, a key regulator of cell death, in the heterozygous Lurcher mutant does not prevent +/Lc Purkinje cell death. To investigate further the mechanisms of +/Lc Purkinje cell death, we have crossed +/Lc mutants with a second line of Hu-bcl-2 transgenics (NSE73a) that shows an earlier onset of transgene expression and higher expression levels. Analysis of eight +/Lc-NSE73a mutants (4 at 2 months and 4 at 5-6 months) showed that Hu-bcl-2 overexpression delayed, but ultimately could not prevent +/Lc Purkinje cell death.

staggerer phenotype in retinoid-related orphan receptor alpha-deficient mice.

Retinoid-related orphan receptor alpha (RORalpha) is a member of the nuclear receptor superfamily. To study its physiological role we generated null-mutant mice by targeted insertion of a lacZ reporter gene encoding the enzyme beta-galactosidase. In heterozygous RORalpha+/- mice we found beta-galactosidase activity, indicative of RORalpha protein expression, confined to the central nervous system, skin and testis. In the central nervous system, the RORalpha gene is expressed in cerebellar Purkinje cells, the thalamus, the suprachiasmatic nuclei, and retinal ganglion cells. In skin, RORalpha is strongly expressed in the hair follicle, the epidermis, and the sebaceous gland. Finally, the peritubular cells of the testis and the epithelial cells of the epididymis also strongly express RORalpha. Recently, it was reported that the ataxic mouse mutant staggerer (sg/sg) is caused by a deletion in the RORalpha gene. The analysis of the cerebellar and the behavioral phenotype of homozygous RORalpha-/- mice proves identity to sg/sg mice. Although the absence of RORalpha causes dramatic developmental effects in the cerebellum, it has no apparent morphological effect on thalamus, hypothalamus, and retina. Similarly, testis and skin of RORalpha-/- mice display a normal phenotype. However, the pelage hair of both sg/sg and RORalpha-/- is significantly less dense and when shaved shows reluctance to regrow.

Inhibition of neuronal (type 1) nitric oxide synthase prevents hyperaemia and hippocampal lesions resulting from kainate-induced seizures.

The possible roles for nitric oxide produced by neurons in epileptic conditions have been investigated from two different aspects: microcirculation and delayed damage. Our aim was to determine whether the selective inhibition of neuronal (type 1) nitric oxide synthase by 7-nitroindazole, during seizures induced by systemic kainate, modifies hippocampal blood flow and oxygen supply and influences the subsequent hippocampal damage. Experiments were performed in conscious Wistar rats whose electroencephalogram was recorded. 7-Nitroindazole (25 mg/kg, i.p.) or its vehicle was injected 30 min before kainate administration (10 mg/kg, i.p.) and then twice at 1-h intervals. Kainate triggered typical limbic seizures evolving into status epilepticus, identified by uninterrupted electroencephalographic spike activity. The seizures were stopped by diazepam (5 mg/kg, i.p.) after 1 h of status epilepticus. Three types of experiments were performed in vehicle- and 7-nitroindazole-treated rats. (1) Hippocampal nitric oxide synthase activity was measured under basal conditions, at 1 h after the onset of the status epilepticus and at 24 h after its termination (n = 4-6 per group). (2) Hippocampal blood flow and tissue partial pressure of oxygen were measured simultaneously by mass spectrometry for the whole duration of the experiment, while systemic variables and body temperature were monitored (n = 6 per group). (3) Hippocampal damage was revealed by Cresyl Violet staining and evaluated with a lesion score seven days after status epilepticus (n = 12 per group). Hippocampal nitric oxide synthase activity was not significantly modified during status epilepticus or the following day in vehicle-treated rats. In contrast, it was inhibited by 57% in 7-nitroindazole-treated rats, both in basal conditions and after 1 h of status epilepticus, but was not different from its basal level 24 h later. 7-Nitroindazole significantly decreased basal hippocampal blood flow and tissue partial pressure in oxygen by 30% and 35%, respectively without affecting any systemic or thermal variable. During status epilepticus, 7-nitroindazole significantly reduced the increase in hippocampal blood flow by 70% and prevented any increase in the tissue partial pressure of oxygen. Seven days later, the hippocampal damage in the CA1 and CA3 layers was significantly less in 7-nitroindazole-treated rats than in vehicle-treated rats. These results indicate that the inhibition of neuronal nitric oxide synthase by 7-nitroindazole protects neurons from seizure-induced toxicity despite reducing blood flow and oxygen supply to the hippocampus.

Fear decrease in transgenic mice overexpressing bcl-2 in neurons.

Neuronal destruction in the amygdala, hypothalamus and cerebellum provokes a diminution in anxiety and neophobia. In transgenic mice that express the human bcl-2 gene under the control of neuron specific enolase promotor (Hu-bcl-2), BCL-2 overexpression reduces the naturally occurring neuronal death, producing an increase of the number of neurons and brain size. Since BCL-2 over-expression has been observed in different parts of the brain and especially in the amygdaloid nuclei, the hypothalamus and the cerebellum, we studied the fear-related behavior of these transgenic mice. Hu-bcl-2 transgenic mice showed a decrease in anxiety and neophobia, indicating that, for this particular behavior, supernumerary neurons elicit the same modification as that observed after neuronal destruction.

Role of the inferior olivary complex in motor skills and motor learning in the adult rat.

The inferior olivary complex of adult rats was chemically destroyed using intraperitoneal injection of 3-acetylpyridine. Animals were submitted to different motor tasks: hanging test, equilibrium test and motor co-ordination test. The different scores show that 3-acetylpyridine-treated rats had motor co-ordination and static equilibrium deficiencies, whereas their rod suspension capabilities were intact. Animals were also trained on an unrotated rod or on a rod rotating at 5, 10 or 20 r.p.m. 3-Acetylpyridine-treated rats were able to maintain their equilibrium on the unrotated rod and at 5 r.p.m. Moreover, after motor training at 5 r.p.m., rats were able to improve their motor skills and reached the same score as controls. Despite their good motor skills, animals were unable to maintain their equilibrium when rotated at 10 and 20 r.p.m. These results suggest that the inferior olivary complex is needed for motor learning involving the temporal organization of movement.