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Biomedical subjects

M Morales

Publications and source records attributed to M Morales.

At least 55 records · Page 3Linked to original sources
PubMed2001

Fetal intra-nigral ventral mesencephalon and kidney tissue bridge transplantation restores the nigrostriatal dopamine pathway in hemi-parkinsonian rats.

We have previously demonstrated that intranigral transplantation of fetal ventral mesencephalic (VM) tissue and nigrostriatal administration of glial cell line-derived neurotrophic factor (GDNF) restores striatal dopamine input in hemiparkinsonian rats. Since it has been found that GDNF is highly expressed in fetal kidney, we examined the possibility that fetal kidney tissue may provide trophic support, similar to GDNF, to an intranigral dopamine (DA) transplant and restore the nigrostriatal pathway. Adult Sprague-Dawley rats were anesthetized and unilaterally injected with 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. Completeness of the lesion was evaluated by measuring amphetamine-induced rotation. One month after 6-OHDA lesioning, fetal VM cells were grafted into the lesioned nigral area followed by transplantation of fetal kidney tissue or vehicle along a pathway from nigra to striatum. Animals receiving these transplants showed a significant decrease both in amphetamine-induced rotation and in postural asymmetry 1 to 3 months after grafting. Immunocytochemical studies demonstrated tyrosine hydroxylase (TH) positive fiber tracts in the lesioned striatum. Control animals that received vehicle injection after the intranigral graft or no transplantation showed no alterations in amphetamine-induced turning and no TH-positive fibers in the lesioned striatum. These results indicate that combinations of fetal nigral and kidney transplants may restore the nigrostriatal DA pathway in Parkinsonian rats. As fetal kidney contains a variety of trophic proteins, it may provide a synergistic admixture to optimally promote DA fiber outgrowth.

Amphetamine↗
PubMed2001

Time course study of GFRalpha-1 expression in an animal model of stroke.

Previous studies have shown that intracerebral administration of glial cell line-derived neurotrophic factor (GDNF) reduces ischemia-mediated cerebral infarction. The biological effects of GDNF are mediated by GDNF-family receptor alpha-1 (GFRalpha-1) and c-Ret. In this study, we examined the levels of expression of GFRalpha-1 and c-Ret in a rat model of stroke. Adult Sprague-Dawley rats were anesthetized with chloral hydrate. The right middle cerebral artery was ligated at its distal branch for 90 min. Animals were sacrificed at 0, 6, 12, and 24 h after reperfusion and levels of expression of GFRalpha-1 and c-Ret mRNA were determined by in situ hybridization histochemistry. We found that GFRalpha-1 mRNA was up-regulated in CA3, dentate gyrus (DG), cortex, and striatum. The peak of up-regulation in DG was 6 h after reperfusion. GFRalpha-1 mRNA levels in CA3 were gradually up-regulated over the 24-h reperfusion period. In cortex, GFRalpha-1 mRNA was up-regulated at all time points; however, the peak of up-regulation was observed at 0 and 24 h after reperfusion. In striatum, an initial up-regulation of GFRalpha-1 was found at 0 h after ischemia. In striatum, up-regulation of c-Ret mRNA was detected as early as 0 h after reperfusion. A gradual increase was found at 6, 12, and 24 h after reperfusion. In conclusion, our results indicate that there are both regional and temporal differences in up-regulation of GFRalpha-1 and c-Ret after ischemia. Since GDNF is neuroprotective, up-regulation of GFRalpha-1 and c-Ret could enhance the responsiveness to GDNF and reduce neuronal damage. The selective up-regulation of GFRalpha-1 and c-Ret in different brain areas suggests that there may be regional differences in GDNF-induced neuroprotection in stroke.

Analysis of Variance↗
PubMed2001

In vivo extracellular recording of striatal neurons in the awake rat following unilateral 6-hydroxydopamine lesions.

The purpose of this study was to further understand the functional effects of dopaminergic input to the dorsal striatum and to compare the effects of dopaminergic lesions in awake and anesthetized animals. We examined the effects of unilateral 6-hydroxydopamine (6-OHDA) lesions of the ascending dopaminergic bundle on the firing properties of dorsal striatal neurons in the awake freely moving rat using chronically implanted microwire electrode arrays. We recorded extracellular activity of striatal neurons under baseline conditions and following the systemic injection of apomorphine in awake and anesthetized subjects. Firing rates were higher in the hemisphere ipsilateral to the 6-OHDA lesion compared to rates of neurons from the contralateral unlesioned hemisphere. Striatal firing rates from sham and no-surgery control rats were, in general, higher than those from the contralateral unlesioned striatum of experimental subjects. Apomorphine (0.05 mg/kg, sc) normalized the differences in firing rates in lesioned animals by increasing firing of neurons within the contralateral unlesioned side, while simultaneously decreasing firing of neurons within the ipsilateral lesioned side. Mean firing rates were substantially higher in awake animals than in subjects anesthetized with chloral hydrate, perhaps reflecting anesthesia-induced decreases in excitatory input to striatal neurons. Chloral hydrate anesthesia decreased firing rates of neurons in the lesioned, unlesioned, and control striata to a similar degree, although absolute firing rates of neurons from the 6-OHDA-lesioned striata remained elevated over all other groups. Unilateral 6-OHDA lesions also altered the pattern of spike output in the awake animal as indicated by an increase in the number of bursts per minute following dopaminergic deafferentation. This and other burst parameters were altered by apomorphine. Our findings show that effects of dopaminergic deafferentation can be measured in the awake behaving animal; this model should prove useful for testing the behavioral and functional effects of experimental manipulations designed to reduce or reverse the effects of dopaminergic cell loss. In addition, these results suggest that the contralateral changes in striatal function which occur in the unilateral dopaminergic lesion model should be considered when evaluating experimental results.

Action Potentials↗
PubMed2001

Time-dependent changes in extinction behavior and stress-induced reinstatement of drug seeking following withdrawal from heroin in rats.

RATIONALE AND OBJECTIVES: Footshock stress reliably reinstates heroin seeking in rats, but the time course of the development of this effect following drug withdrawal is not known. Here we studied the effect of intermittent footshock stress on reinstatement of heroin seeking following different withdrawal periods (1-66 days). We also studied whether changes in corticotropin-releasing factor (CRF) mRNA in the central nucleus of the amygdala (CeA) and the bed nucleus of the stria terminalis (BNST) are correlated with this reinstatement after 1 day and 6 days of heroin withdrawal. METHODS: Rats were trained to self-administer heroin (9 h/day; 0.1 mg/kg per infusion) for 10 days. Tests for extinction behavior and footshock-induced reinstatement of heroin seeking were then conducted after 1, 6, 12, 25, or 66 days of heroin withdrawal. On the test day, rats were given five to ten 60-min extinction sessions until they reached the extinction criterion of less than 15 responses per 60 min on the lever previously associated with heroin. Rats were then exposed to intermittent foot-shock (0.8 mA; 10 min), and lever-pressing behavior was recorded for 120 min. RESULTS: Reinstatement of lever-pressing behavior by footshock followed an inverted U-shaped curve with maximal responding after 6 days and 12 days of heroin withdrawal. Surprisingly, foot-shock did not reinstate lever-pressing behavior on day 1 of withdrawal. Lever pressing during extinction, prior to exposure to footshock, also followed an inverted U-shaped curve, with higher responding after 6, 12, and 25 days of heroin withdrawal. Finally, compared with control groups not exposed to shock, CRF mRNA levels in response to footshock were increased in the CeA (day 1 of withdrawal) and the dorsal BNST (day 1 and day 6), but not in the ventral BNST. CONCLUSIONS: The duration of the heroin withdrawal period is an important factor in the manifestation of (1) footshock stress-induced reinstatement of heroin seeking and (2) extinction of the heroin-reinforced behavior. Finally, the time-dependent changes in footshock stress-induced reinstatement following withdrawal from heroin were not correlated with alterations in CRF mRNA in the CeA and BNST.

Animals↗
PubMed2001

Going home: giving voice to memory strategies of young Mayan refugees who returned to Guatemala as a community.

Around 1982, thousands of Guatemalan Mayas fled their villages and lands to escape the Rios Montt scorched-earth policy implemented in rural areas. After more than a decade of exile, many of those refugees have returned to their homeland. This paper looks at the ways in which young Mayan refugees who have returned home after extended exile in Mexico appropriate and distance themselves from the collective project of going home. Two Mayan communities of retornados (returnees), whose paths into exile and home again differ slightly, are compared. Outside support from international organizations and cohesion in the refugee camps enabled the young people of La Victoria to see disclosure of the traumatic past from a position of strength and confrontation as the key to social change. In La Esperanza, the past is rebuilt by the youth around avoidance of recent history, and tradition appears as a bridge between past and future. The way the youth of the two communities construct their homecoming demonstrates how small changes in the migration experience may result in considerable differences in the choice of strategies, and raises important questions about assistance programs that might be developed for these populations.

Adolescent↗
PubMed2001

Dilated cardiomyopathy in Presa canario dogs: ECG findings.

Forty-seven Presa canario dogs were diagnosed with congestive heart failure due to dilated cardiomyopathy (DCM). Supraventricular or ventricular tachydysrhythmias were found in 29 dogs. Atrial fibrillation was the most common dysrhythmia. Ventricular dysrhythmias were observed infrequently and had a very important prognostic value in Presa canario dogs with DCM. Abnormalities of cardiac conduction were diagnosed in 16 (34%) dogs and changes in wave morphology were found in 29 (62%) dogs. Normal sinus rhythm was recorded in only 12 (26%) Presa canario dogs with DCM.

Animals↗
PubMed2001

Methyl tert-butyl ether (MTBE) degradation by a microbial consortium.

The widespread use of methyl tert-butyl ether (MTBE) as a gasoline additive has resulted in a large number of cases of groundwater contamination. Bioremediation is often proposed as the most promising alternative after treatment. However, MTBE biodegradation appears to be quite different from the biodegradation of usual gasoline contaminants such as benzene, toluene, ethyl benzene and xylene (BTEX). In the present paper, the characteristics of a consortium degrading MTBE in liquid cultures are presented and discussed. MTBE degradation rate was fast and followed zero order kinetics when added at 100 mg l(-1). The residual MTBE concentration in batch degradation experiments ranged from below the detection limit (1 microg l(-1)) to 50 microg l(-1). The specific activity of the consortium ranged from 7 to 52 mgMTBE g(dw)(-1) h(-1) (i.e. 19-141 mgCOD g(dw) (-1) h(-1)). Radioisotope experiments showed that 79% of the carbon-MTBE was converted to carbon-carbon dioxide. The consortium was also capable of degrading a variety of hydrocarbons, including tert-butyl alcohol (TBA), tert-amyl methyl ether (TAME) and gasoline constituents such as benzene, toluene, ethylbenzene and xylene (BTEX). The consortium was also characterized by a very slow growth rate (0.1 d(-1)), a low overall biomass yield (0.11 gdw g(-1)MTBE; i.e. 0.040 gdw gCOD(-1)), a high affinity for MTBE and a low affinity for oxygen, which may be a reason for the slow or absence of MTBE biodegradation in situ. Still, the results presented here show promising perspectives for engineering the in situ bioremediation of MTBE.

Bacteria↗
PubMed2001

Homeopathy in Cuban epidemic neuropathy: an open clinical trial.

In an outbreak of epidemic neuropathy (EN) in Cuba (1992-1993), most patients were improved by vitamin therapy. In subjects with residual symptoms, alternative treatments including homeopathy were suggested to ameliorate optic and peripheral signs of the disease. An open clinical pilot trial was conducted on 31 patients with long standing symptoms of optic (OPTI group, n=15) or peripheral EN (PERI group, n=16). During the trial, OPTI and PERI patients continued the same treatment that they received before. Carboneum sulphuratum and Tabacum in homeopathic dilutions were administered for 30 days. These medicines are specific to optic EN, but not closely linked with peripheral EN. Clinical status was evaluated by neurological and ophthalmologic tests at diagnosis (Ddiag), 7 days before homeopathic treatment (D0) and 90 days after (D90). From D0 to D90, the percentages of improvement were 73.3% for the OPTI form and 12.5% for the PERI form. The percentage of improved OPTI patients was significantly higher after the homeopathic treatment vs the period between Ddiag and D0 for optical EN (P<0.01), but not for PERI subjects (P>0.05). In the OPTI group, colour vision, visual acuity and visual field improved after homeopathic treatment (P<0.001), these parameters did not change between Ddiag and D90 (P>0.05). Carboneum sulphuratum and Tabacum showed a reasonable effectiveness in optical EN, but were not effective in PERI EN.

Cuba↗
PubMed2001

Sociodemographic characteristics and HIV risk behaviour patterns of male sex workers in Madrid, Spain.

This paper describes the sociodemographic and work characteristics, prevalence of HIV infection and associated risk behaviours among male sex workers (MSWs) in Madrid (Spain). Using an anonymous semi-structured questionnaire, educators attached to a mobile unit under a street-based prostitution programme surveyed 84 MSWs from several Madrid areas. Of the total surveyed: 35% were immigrants, mean age was 23 years, mean period in prostitution was four years; 21% had no primary education; 16% had injected drugs at some time; 11% reported private sexual relationships exclusively with women; 89% always used condoms in anal practices with clients; and 41% were in sexual relationships with their partners. Only 11% had ever used fortified condoms. In the preceding month, 37% had experienced condom failure, 82% without having used any lubricant. In all, 67% reported having undergone HIV testing, with a higher percentage of positive results among injecting (60%) versus non-injecting drug users (17%). Immigrants had a lower level of education, made less use of condoms, had more condom failures and, in their private lives, a greater proportion reported sexual relationships exclusively with women. In Spain, MSWs should be included in HIV prevention programmes, which ought to be specifically adapted to immigrants. Priority should be given to reducing the condom failure rate in anal intercourse, by improving access to fortified condoms.

Adolescent↗
PubMed2001

Bioelectrical impedance analysis of the body composition of Nigerian children with calcium-deficiency rickets.

Children with calcium-deficiency rickets experience increased urinary excretion of both essential and non-essential amino acids compared to non-rachitic children of the same age. Chronic wastage of amino acids into the urine could lead to a deficit in fat-free mass (FFM) in rachitic children. We therefore determined the FFM of children with calcium-deficiency rickets in northern Nigeria using bioelectrical impedance analysis. Because of the leg deformities present in the rachitic subjects, we calculated a 'corrected' height for each rachitic subject using the relationship between arm length and height in non-rachitic subjects over the same age range (r = 0.94). A total of 28 children (4 male and 24 female), 2-9 years of age with calcium-deficiency rickets and an equal number of age- and gender-matched controls were recruited into the study. Resistance and reactance measurements were obtained for all subjects and the total body water was calculated using age-specific equations. FFM was then calculated using age- and gender-specific hydration constants. No significant differences were found in the weights or FFM between the rachitic subjects and the controls (8.41 kg +/- 2.19 vs. 8.85 kg +/- 1.90, respectively). We conclude that chronic urinary wastage of amino acids by rachitic children does not result in a deficit in FFM.

Amino Acids↗
PubMed2001

Exocrine pancreatic insufficiency in tropical sprue.

BACKGROUND: Pancreatic insufficiency may appear secondary to several intestinal disorders. It may contribute to malabsorption in tropical sprue (TS). METHODS: The exocrine pancreatic function was evaluated with the indirect pancreolauryl test (PT) in 56 patients with TS. The PT results were analyzed and correlated with serum albumin levels, degree of intestinal atrophy, and steatorrhea. RESULTS: Abnormally low values were found in 36 (64.2%) cases. A significant relationship was not observed between PT and hypoalbuminemia. Patients with more severe damage by intestinal biopsy tended to have lower PT values. No relationship was found between pancreatic insufficiency and steatorrhea (expressed as g/24 h), but patients with pancreatic insufficiency had increased stool fat concentrations (expressed as percentage of wet stool weight). All patients responded favorably to treatment with folic acid and tetracycline. Fifteen patients with abnormal initial PT values underwent a repeat PT after a 6-week therapy; all of them showed normalization of PT values. CONCLUSIONS: The abnormal exocrine pancreatic function found with an indirect test in patients with TS is probably secondary to a low pancreatic hormonal stimulation due to intestinal damage, as occurs in celiac sprue. These abnormalities are reversible after specific treatment for TS.

Adolescent↗
PubMed2001

Bone morphogenetic protein-6 reduces ischemia-induced brain damage in rats.

BACKGROUND AND PURPOSE: Bone morphogenetic protein-6 (BMP6) and its receptors are expressed in adult and fetal brain. Receptors for BMP6 are upregulated in adult brain after injury, leading to the suggestion that BMP6 is involved in the physiological response to neuronal injury. The purpose of this study was to determine whether there was a neuroprotective effect of BMP6 in vivo and in vitro. METHODS: Lactate dehydrogenase and microtubule-associated protein-2 (MAP-2) activities were used to determine the protective effect of BMP6 against H(2)O(2) in primary cortical cultures. The neuroprotective effects of BMP6 were also studied in chloral hydrate-anesthetized rats. BMP6 or vehicle was injected into right cerebral cortex before transient right middle cerebral artery (MCA) ligation. Animals were killed for triphenyl-tetrazolium chloride staining, caspase-3 immunoreactivity and enzymatic assays, and TUNEL assay. A subgroup of animals were used for locomotor behavioral assays. RESULTS: Application of H(2)O(2) increased lactate dehydrogenase activity and decreased the density of MAP-2(+) neurons in culture. Both responses were attenuated by BMP6 pretreatment. Complementary in vivo studies showed that pretreatment with BMP6 increased motor performance and generated less cerebral infarction induced by MCA ligation/reperfusion in rats. Pretreatment with BMP6 did not alter cerebral blood flow or physiological parameters. There was decreased ischemia-induced caspase-3 immunoreactivity, caspase-3 enzymatic activity, and density of TUNEL-positive cells in ischemic cortex in BMP6-treated animals. CONCLUSIONS: BMP6 reduces ischemia/reperfusion injury, perhaps by attenuating molecular events underlying apoptosis.

Animals↗
PubMed2001

Uterine prolapse in 2 dromedary camels.

Two cases of uterine prolapse in dromedary camels in a herd with concomitant cases of white muscle disease are described. Serum selenium and glutathione peroxidase in whole blood were investigated in both patients and showed statistical difference compared with a control group. Results suggest that selenium deficiency could promote uterine prolapse in dromedary camels.

Animals↗
PubMed2001

[Spontaneous bacterial peritonitis in hepatic cirrhosis with ascites: incidence, bacteriology and mortality in Uruguay].

Spontaneous bacterial peritonitis (SBP) is a frequent and severe complication of cirrhotic patients with ascites. In order to analyze the incidence, bacteriology and in-hospital mortality, we studied 64 consecutive patients with cirrhosis and ascites (47 males, 17 females average age 59 years) hospitalized in a general adults 3rd level hospital (Pasteur hospital, Montevideo, Uruguay), between September 1998 and May 2000. The diagnostic criteria was more than 250 polymorphonuclear cells/cu.mm. in ascitic fluid and/or a positive culture. We found 17 SBP in 17 patients (10 males 24-81 years) which means an incidence of 26.56%. 15 alcoholic cirrhosis and 2 autoimmune disease. 12% (2/17) were asymptomatic; 8/17 were SBP culture positive (5 E. Coli, 2 St. Pneumoniae, 1 Klebsiella sp.), and 9 were culture negative. The mortality rate associated with SBP was 47% (8/17), greater than the cirrhotic group without SBP (12.7% p < 0.01).

Adult↗
PubMed2000

GFR alpha-1 is expressed in parvalbumin GABAergic neurons in the hippocampus.

Glial cell line derived neurotrophic factor (GDNF) is a potent survival factor for several types of neurons. GDNF binds with high affinity to GDNF-family receptor alpha-1 (GFR alpha-1). This receptor is expressed in different areas of the brain, including the hippocampus and dentate gyrus. By using in situ hybridization and immunohistochemistry, we found that 19% to 37% of glutamic acid decarboxylase (GAD) expressing neurons co-expressed GFR alpha-1 in the hippocampus. GFR alpha-1/GAD co-expression was found mainly in the stratum (s) pyramidale (29-37%) and s. oriens (20-25%). Further characterization of GFR alpha-1 expressing interneurons, based on their calcium-binding protein immunoreactivity, demonstrated that many parvalbumin (PV) immunoreactive neurons express GFR alpha-1 in the s. pyramidale of CA1 (72%), CA2 (70%) and CA3 (70%) subfields of the hippocampus. GFR alpha-1/PV double labeled neurons were also detected in the s. oriens of CA1 (52%), CA2 (27%) and CA3 (36%) subfields. The expression of GFR alpha-1 in principal neurons and in a specific sub-population of GABAergic neurons (PV-containing neurons) suggest that GDNF might modulate, in a selective manner, functions of the entire adult hippocampus.

Animals↗
PubMed2000

Safety evaluation of a recombinant myxoma-RHDV virus inducing horizontal transmissible protection against myxomatosis and rabbit haemorrhagic disease.

We have recently developed a transmissible vaccine to immunize rabbits against myxomatosis and rabbit haemorrhagic disease based on a recombinant myxoma virus (MV) expressing the rabbit haemorrhagic disease virus (RHDV) capsid protein [Bárcena et al. Horizontal transmissible protection against myxomatosis and rabbit haemorragic disease using a recombinant myxoma virus. J. Virol. 2000;74:1114-23]. Administration of the recombinant virus protects rabbits against lethal RHDV and MV challenges. Furthermore, the recombinant virus is capable of horizontal spreading promoting protection of contact animals, thus providing the opportunity to immunize wild rabbit populations. However, potential risks must be extensively evaluated before considering its field use. In this study several safety issues concerning the proposed vaccine have been evaluated under laboratory conditions. Results indicated that vaccine administration is safe even at a 100-fold overdose. No undesirable effects were detected upon administration to immunosuppressed or pregnant rabbits. The recombinant virus maintained its attenuated phenotype after 10 passages in vivo.

Animals↗