Biomedical subjects

G Cano

Publications and source records attributed to G Cano.

At least 19 recordsLinked to original sources

PubMed2002

Distribution of fumonisins in dry-milled corn fractions in Argentina.

Corn samples and different dry-milled fractions collected from an industrial mill in Argentina were analysed. Average contaminations were FB(1) 1540 microg kg(-1), FB(2) 716 microg kg(-1) and FB(3) 152 microg kg(-1) in whole corn; FB(1) 135 microg kg(-1), FB(2) 39.1 microg kg(-1) and FB(3) 10.2 microg kg(-1) in corn grits; FB(1) 358 microg kg(-1), FB(2) 122 microg kg(-1) and FB(3) 45.9 microg kg(-1) in 'C' flour; FB(1) 148 microg kg(-1), FB(2) 52.5 microg kg(-1) and FB(3) 28.3 microg kg(-1) in corn meal; and FB(1) 4210 microg kg(-1), FB(2) 2010 microg kg(-1) and FB(3) 447 microg kg(-1) in germ and bran together. The fumonisin contamination level was approximately three times higher in germ and bran than in whole corn, 13 times higher than in 'C' flour and 29 times higher than in corn meal and corn grits. Taking into account the distribution of fumonisins in commercial dry-milled corn fractions and corn meal consumption in Argentina, a theoretical whole corn level of 6640 microg kg(-1) maximum of total fumonisins could be processed to obtain products considered safe for human health.

Argentina↗

PubMed2001

Characterization of the central nervous system innervation of the rat spleen using viral transneuronal tracing.

Splenic immune function is modulated by sympathetic innervation, which in turn is controlled by inputs from supraspinal regions. In the present study, the characterization of central circuits involved in the control of splenic function was accomplished by injecting pseudorabies virus (PRV), a retrograde transynaptic tracer, into the spleen and conducting a temporal analysis of the progression of the infection from 60 hours to 110 hours postinoculation. In addition, central noradrenergic cell groups involved in splenic innervation were characterized by dual immunohistochemical detection of dopamine-beta-hydroxylase and PRV. Infection in the CNS first appeared in the spinal cord. Splenic sympathetic preganglionic neurons, identified in rats injected with Fluoro-Gold i.p. prior to PRV inoculation of the spleen, were located in T(3)-T(12) bilaterally; numerous infected interneurons were also found in the thoracic spinal cord (T(1)-T(13)). Infected neurons in the brain were first observed in the A5 region, ventromedial medulla, rostral ventrolateral medulla, paraventricular hypothalamic nucleus, Barrington's nucleus, and caudal raphe. At intermediate survival times, the number of infected cells increased in previously infected areas, and infected neurons also appeared in lateral hypothalamus, A7 region, locus coeruleus, subcoeruleus region, nucleus of the solitary tract, and C3 cell group. At longer postinoculation intervals, infected neurons were found in additional hypothalamic areas, Edinger-Westphal nucleus, periaqueductal gray, pedunculopontine tegmental nucleus, caudal ventrolateral medulla, and area postrema. These results demonstrate that the sympathetic outflow to the spleen is controlled by a complex multisynaptic pathway that involves several brainstem and forebrain nuclei.

Animals↗

PubMed2000

Connections of Barrington's nucleus to the sympathetic nervous system in rats.

Barrington's nucleus (BN) has been considered a pontine center related exclusively to the control of pelvic parasympathetic activity. The present study demonstrates an anatomical linkage between BN and autonomic outflow to visceral targets innervated exclusively by the sympathetic division of the autonomic nervous system. Temporal analysis of infection after injection of pseudorabies virus (PRV), a retrograde transynaptic tracer, into two sympathetically innervated organs, the spleen and the kidney, revealed the presence of infected neurons in BN at early post-inoculation survival intervals. Immunohistochemical localization of PRV after spleen injections showed that a small subpopulation of BN neurons became labeled in a time frame coincident with the appearance of infected neurons in other brain regions known to project to sympathetic preganglionic neurons (SPNs) in the thoracic spinal cord; a larger number of infected neurons appeared in BN at intermediate intervals after PRV injections into the spleen or kidney. Coinjection of the retrograde tracer Fluoro-Gold i.p. and PRV into the spleen demonstrated that parasympathetic preganglionic neurons in the caudal medulla or lumbo-sacral spinal cord were not infected, indicating that infected BN neurons were not infected via a parasympathetic route. Thus, BN neurons become infected after PRV injections into the spleen or kidney either directly through BN projections to SPNs, or secondarily via BN projections to infected pre-preganglionic neurons. These results demonstrate an anatomical linkage, either direct or indirect, between BN and sympathetic activity. Because BN receives numerous inputs from diverse brain regions, the relation of BN with both branches of the autonomic nervous system suggests that this nucleus might play a role in the integration of supraspinal inputs relevant to the central coordination of sympathetic and parasympathetic activity.

Animals↗

PubMed2000

Role of locus coeruleus in foot shock-evoked Fos expression in rat brain.

The robust activation of locus coeruleus neurons in response to a variety of stressors, in conjunction with the widespread outputs of the locus coeruleus, suggest that the locus coeruleus may be important in mediating responses to stress. Previous studies in rats have demonstrated that exposure to foot shock elicits Fos expression, a marker of neuronal activation, in the locus coeruleus and other brain sites. In order to evaluate the involvement of the locus coeruleus in foot shock-induced activation of other brain sites, shock-induced Fos expression was examined in the locus coeruleus and other brain areas known to be activated by foot shock, following direct inhibition of the locus coeruleus by local infusion of muscimol, a GABA agonist, prior to foot shock. Control rats received infusions of artificial cerebrospinal fluid into the locus coeruleus or muscimol into areas outside of locus coeruleus. Rats infused with artificial cerebrospinal fluid and then exposed to foot shock had significant increases in Fos expression in several brain areas, including locus coeruleus, nucleus O, several subdivisions of the hypothalamus, subnuclei of amygdala, bed nucleus of the stria terminalis and cingulate cortex. Inhibition of the locus coeruleus prior to foot shock significantly inhibited Fos expression in the locus coeruleus, nucleus O, some subdivisions of the hypothalamus including the magnocellular and medial parvicellular paraventricular hypothalamic nucleus, subnuclei of amygdala, and cingulate cortex. In contrast, inhibition of the locus coeruleus did not affect shock-induced Fos expression in other areas, including certain subdivisions of the hypothalamus and bed nucleus of the stria terminalis. We suggest that foot shock may activate multiple pathways, with activation of certain discrete nuclei requiring input from the locus coeruleus and activation of others occurring independently of locus coeruleus input.

Animals↗

PubMed1999

Dynorphin A increases substance P release from trigeminal primary afferent C-fibers.

Dynorphin A-(1-17) has been found to produce spinal antianalgesia and allodynia. Thus, we studied whether dynorphin A-(1-17) modulates substance P release evoked by the C-fiber-selective stimulant capsaicin (1 microM) from trigeminal nucleus caudalis slices. Very low concentrations of dynorphin A-(1-17) (0.01-0.1 nM) strongly facilitated capsaicin-evoked substance P release. This dynorphin A-(1-17) effect was not blocked by the opioid receptor antagonists naloxone (100 nM), beta-funaltrexamine (20 nM), naloxonazine (1 nM), nor-binaltorphimine (3 nM) and ICI 174,864 (N,N-dialyl-Tyr-Aib-Phe-Leu; 0.3 microM). Yet, the effect of dynorphin A-(1-17) was blocked by the NMDA receptor antagonist MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cyclohepten-5-10-imine maleate; 0.3 microM). Neonatal treatment with capsaicin (50 mg/kg s.c.), which destroys substance P-containing primary afferents, abolished the excitatory effect of dynorphin A-(1-17) on K+-evoked substance P release. In conclusion, dynorphin A-(1-17) increases substance P release from C-fibers by the activation of NMDA receptors which supports the involvement of presynaptic mechanisms in dynorphin-induced antianalgesia and allodynia.

Animals↗

PubMed1999

Opposite modulation of capsaicin-evoked substance P release by glutamate receptors.

Substance P and glutamate are present in primary afferent C-fibers and play important roles in persistent inflammatory and neuropathic pain. In the present study, we have examined whether activation of different glutamate receptor subtypes modulates the release of substance P evoked by the C-fiber selective stimulant capsaicin (1 microM) from rat trigeminal nucleus slices. The selective NMDA glutamate receptor agonist L-CCG-IV (1-10 microM) enhanced capsaicin-evoked substance P release about 100%. This facilitatory effect was blocked by 0.3 microM MK-801, a selective NMDA receptor antagonist. The metabotropic glutamate receptor agonists L-AP4 (group III) and DHPG (group I) (30-100 microM) inhibited capsaicin-evoked substance P release by approximately 60%. These inhibitory effects were blocked by the selective metabotropic glutamate receptor antagonist (+/-)-MCPG (5 microM). On the other hand, AMPA and kainate (0.1-10 microM), did not significantly affect capsaicin-evoked substance P release. Thus, substance P release from non-myelinated primary afferents, and possibly nociception, may be under the functional antagonistic control of some metabotropic and ionotropic glutamate receptor subtypes.

Afferent Pathways↗

PubMed1999

Multiphasic morphine modulation of substance P release from capsaicin-sensitive primary afferent fibers.

Morphine produces a multiphasic modulation of K+-evoked substance P release from trigeminal slices and dorsal root ganglion neurons in culture. We now found that the C-fiber stimulant, capsaicin (1 microM), evoked release of substance P that was inhibited, enhanced and inhibited by 0.1 nM, 1 microM, and 10 microM morphine, respectively. This morphine's multiphasic effect was blocked by naloxone (100 nM). Neonatal treatment with capsaicin produced thermal hypoalgesia and abolished the multiphasic effect of morphine on substance P release evoked by 50 mM K+. These findings suggest that the multiphasic modulation of substance P release by morphine is dependent on C-type afferents and may be of relevance to nociception.

Animals↗

PubMed1999

A survey of fumonisins, deoxynivalenol, zearalenone and aflatoxins contamination in corn-based food products in Argentina.

The presence of mycotoxins in corn-based foods available in Argentina was determined in order to make a preliminary exposure assessment. Thirty-eight samples [corn meal ('polenta') and corn flakes] of different local brands were analysed for zearalenone, deoxynivalenol and aflatoxins by TLC and fumonisins (FB1, FB2 and FB3) by HPLC. None of the 38 samples contained any detectable amount of aflatoxins (< 2 micrograms/kg), zearalenone (< 50 micrograms/kg) and deoxynivalenol (< 50 micrograms/kg). By contrast fumonisin contamination was found in 95% of the samples. The highest fumonisin levels were found in corn meal: FB1 (range positives: 60-2860 micrograms/kg; mean positive value: 556 micrograms/kg), FB2 (61-1090 micrograms/kg; 232 micrograms/kg) and FB3 (18-1015 micrograms/kg; 150 micrograms/kg). Low levels of fumonisin B1 were detected in 16/17 corn flakes samples (2-38 micrograms/kg). Total fumonisin levels in corn meal were more than 1000 micrograms/kg in 24% (5/21) of the samples. Although it is not the staple food in Argentina, maize consumption is very important, especially among children. A daily fumonisin intake of 11.3 micrograms/kg of body weight was estimated for child consumers (1-5 years old) based on an average consumption of 200 g of corn meal/day. Calculated at an average rate for all children (consumers or not) the intake estimate was 0.9 microgram/kg of body weight.

Aflatoxins↗

PubMed1999

Coronal suture response to distraction osteogenesis in rabbits with delayed-onset craniosynostosis.

Recent studies have identified a subpopulation of persons with craniosynostosis who exhibit progressive or delayed-onset synostosis and mild cranial vault deformities. These persons may be good candidates for nonextirpation distraction osteogenesis. The present studies were designed to determine force-displacement parameters and assess the effects of distraction osteogenesis on coronal suture growth and morphologic characteristics in a rabbit model with congenital, delayed-onset craniosynostosis. Data were collected from a total of 178 rabbits: 71 normal controls; 16 normal controls with distraction; 72 with delayed-onset coronal suture synostosis; and 19 with delayed-onset coronal suture synostosis and distraction. At 10 days of age, all rabbits had amalgam markers placed on both sides of the coronal suture. In the force-displacement study, force-displacement distractors were placed across the coronal suture and distracted acutely for 1.0 mm at 42 days of age. Force-displacement curves for the coronal suture were best described by a third-order polynomial regression equation for both normal and synostosed groups. Significant differences (P < 0.05) were found in the mean force necessary to distract a normal suture 1 mm in distance (13.72 kg) compared with a suture with delayed-onset synostosis (48.39 kg). A significant (P < 0.05) relationship was also found between the extent of synostosis and the distractive force in rabbits with delayed-onset synostosis. In the distraction study, internal distractors were fixed across the coronal suture at 25 days of age and percutaneously and intermittently activated at an average of 0.11 mm/day for 42 days (4.54 mm total). Serial radiographs were taken at 10, 25, 42, and 84 days of age. Results revealed that rabbits with delayed-onset synostosis and distraction had significantly (P < 0.01) more coronal suture growth rates compared with rabbits with delayed-onset synostosis and no distraction. Coronal sutures were harvested at 84 days of age for qualitative histologic examination. Normal, distracted coronal sutures showed widened sutural ligaments and thin, active osteogenic fronts. In contrast, distracted coronal sutures from rabbits with delayed-onset synostosis showed narrowed sutural ligaments, thickened and blunt osteogenic fronts, and increased collagen and bony matrix deposition compared with controls. Results suggest that distraction osteogenesis without corticotomy may be a treatment alternative in persons with progressive, delayed-onset synostosis. However, these preliminary data also suggest that distractive forces may accelerate or stimulate osteogenesis differentially in persons with craniosynostosis, possibly through an underlying genetic disorder of bone and cytokine regulation. These differential osteogenic responses to distraction, if validated clinically, will need to be taken into account when planning distraction rate and rhythm protocols for patients with craniosynostosis.

Age of Onset↗

PubMed1997

Motor activity and quantitative autoradiographic analysis of muscarinic receptors in the brain of rats subjected to the forced swimming test.

A cholinergic dysfunction has been involved in the neurobiological mechanisms of stress and depression. In the present study, we determined the autoradiographic distribution of muscarinic cholinergic receptors in the brain of rats subjected to the forced swimming test for 15 days. Motor activity was automatically analyzed daily before swimming. In the forced swimming test group, both total horizontal activity and ambulatory movements exhibited a significant decrease, when the data from 1st and 15th day were compared. Neither the affinity of [3H]-quinuclidinyl benzilate nor the maximal number of receptors were affected by the forced swimming test in the caudate-putamen, cortex, and hippocampus. The distribution of [3H]-quinuclidinyl benzilate binding sites did not show significant differences in the 30 analyzed areas. Further analysis of muscarinic receptor subtypes after forced swimming test would be necessary to discard any cholinergic involvement.

Animals↗

PubMed1996

Manganese poisoning reduces strychnine-insensitive glycine binding sites in the globus pallidus of the mouse brain.

Manganese (Mn) poisoning is characterized by central nervous system manifestations, including psychiatric disturbances and extrapyramidal disorders. This metal is thought to produce neuronal degeneration due to cytotoxic products originated by oxidative stress and through an indirect excitotoxic process. In previous studies, we have found a reduction in the density of N-methyl-D-aspartate (NMDA) recognition sites in some brain areas of Mn-treated mice. Due to the close relationship between NMDA sites and strychnine-insensitive glycine (Gly) modulatory sites in the NMDA receptor complex, the [3H]-glycine ([3H]-Gly) binding was analyzed by autoradiographic methods in the brain of mice treated with manganese chloride for 8 weeks. Among all analyzed areas, only the globus pallidus showed a significant reduction in [3H]-Gly binding (27-28%). The Gly binding decrease, focalized in the globus pallidus, could reflect a degeneration of structures containing strychnine-insensitive Gly receptors, since this area is the most frequently reported damaged brain region in Mn intoxication. However, it might also be due to a Gly receptor down-regulation to control NMDA complex activation during Mn poisoning.

Animals↗

PubMed1993

Hydromyelia associated with a posterior fossa cyst.

There are rare reports of children with hydromyelia in association with arachnoid cysts at the foramen of Magendie, and these cases have uniformly been associated with hydrocephalus. We report a case of a 45-year-old woman with a posterior fossa cyst associated with hydromyelia and normal ventricles. This was successfully treated with a cystoperitoneal shunt. We believe this unusual condition is of interest in elucidating potential mechanisms of hydromyelia.

Cerebellar Diseases↗

PubMed1993

Pylephlebitis associated with diverticulitis.

We have reported the cases of two patients who had acute pylephlebitis associated with portal vein thrombosis and septic hepatic emboli as a result of right colonic diverticulitis. Although rare, pylephlebitis is a treatable but often lethal complication of intra-abdominal sepsis. Several bacterial pathogens, especially Escherichia coli are associated with pylephlebitis. Early suspicion and prompt antibiotic therapy can lead to resolution of portal vein thrombosis and hepatic abscess formation, resulting in full recovery for the patient. Surgery may not be required. Our two patients received ampicillin--the best first-line drug--until specific antibiotic therapy could be given. Early administration of a broad spectrum antibiotic is essential.

Acute Disease↗

PubMed1993

Cryptosporidium infections in a suburban community in Maracaibo, Venezuela.

A point prevalence survey for Cryptosporidium was conducted in 212 subjects two months to 70 years of age in a suburban area with a low socioeconomic status in Maracaibo City, Venezuela. Single stool specimens were collected and modified Ziehl-Neelsen carbol-fuchsin staining of 10% formalin-preserved stool was used to identify Cryptosporidium oocysts. Direct wet mounts, iron-hematoxylin-stained smears and formalin-ether concentrates were examined to determine the presence of other intestinal parasites. Cryptosporidium infections were identified in 21 subjects (9.9%), with a high percentage of asymptomatic carriers (15 of 21, 71.4%). Six children (28.5%) had gastrointestinal symptoms and four of them were infants. Cryptosporidium was the single detectable potential pathogenic parasite in only five (23.8%) of 21 patients. The infection rate with one or more parasites was high (82%) and multiple infections, including pathogenic helminths and protozoa, were observed in the majority of patients who passed oocysts. Our findings suggest that although Cryptosporidium is an important pathogen, the proportion of asymptomatic carriers may be high in areas of low socioeconomic status in developing countries.

Adolescent↗

PubMed1992

Boron neutron capture therapy for murine malignant gliomas.

Boron neutron capture therapy (BNCT) involves administration of a boron compound followed by neutron irradiation of the target organ. The boron atom captures a neutron, which results in the release of densely ionizing helium and lithium ions that are highly damaging and usually lethal to cells within their combined track length of approximately 12 microns. Prior to Phase I clinical trials for patients with malignant gliomas, mice with glioma 261 intracerebral tumors were fed D,L-3-(p-boronophenyl)alanine and irradiated with total tumor doses of 1000-5000 RBE-cGy of single fraction thermal neutrons to determine the maximum tolerated dose and effect on survival. These mice were compared to mice that received D,L-3-(p-boronophenyl)alanine alone, neutron irradiation alone, photon irradiation alone, or no treatment. Additional normal mice received escalating doses of neutron irradiation to determine its toxicity to normal brain. BNCT caused a dose-dependent, statistically significant prolongation in survival at 1000-5000 RBE-cGy. At 3000 RBE-cGy, median survival rates of the BNCT and untreated control groups were 68 and 22 days, respectively, with a long-term survival rate of 33%. At 4000 RBE-cGy, median survival was 72 and 21 days, respectively, with a long-term survival rate of 43%. At lower radiation doses, the extended survival was comparable between the BNCT and photon-irradiated mice; however, at 3000 and 4000 RBE-cGy the median survival of BNCT-treated mice was significantly greater than photon-irradiated mice. The maximum tolerated single fraction dose to normal brain was approximately 2000 RBE-cGy.

Animals↗

PubMed1992

Cryptosporidiosis among patients with acquired immunodeficiency syndrome in Zulia State, Venezuela.

We studied the prevalence of Cryptosporidium in 29 patients with acquired immunodeficiency syndrome (AIDS) from Zulia State, Venezuela. They ranged in age from five months to 46 years. Two were children and 27 were adults, of which six were women. Of the 21 men, 66.6% reported homosexual behavior. Three stool samples from each patient were examined, and modified Ziehl-Neelsen carbolfuchsin staining of formalinether stool concentrates was used to identify Cryptosporidium oocysts. To detect the presence of other intestinal parasites, direct wet mounts and iron-hematoxylin-stained smears were examined. Cryptosporidium was found in 12 (41.3%) of the patients and was identified as a single parasitic infection in seven of the 12 patients (58.3%). Other pathogenic parasites encountered were Giardia lamblia (3 of 12, 25%), Entamoeba histolytica (1 of 12, 8.3%), Ascaris lumbricoides, Trichuris trichiura, and Strongyloides stercoralis (each 1 of 12, 8.3%). Blastocystis hominis, an organism with an uncertain taxonomic position and pathogenicity, was observed in three of 12 patients (25%). An inflammatory exudate was observed in 10 of 12 patients infected with Cryptosporidium. Most of the patients with this infection presented with chronic watery diarrhea and weight loss. Our results suggest that Cryptosporidium is very common in AIDS patients with diarrhea in Venezuela. However, the role of this parasite as an enteropathogen in these patients is uncertain.

AIDS-Related Opportunistic Infections↗

PubMed1992

[Chronic manganese poisoning: autoradiographic quantification of cholinergic muscarinic receptors in mouse brain].

Chronic administration of manganese chloride (5 mg Mn/kg body weight/day) during nine weeks, did not affect the [3H]-quinuclidinyl benzilate binding to muscarinic cholinergic receptors in mouse brain. The quantitation and anatomical distribution of the receptors were determined by autoradiographic methods on coronal sections of midbrain and olfactory bulb. It is concluded that, in our experimental conditions, no alteration in the density of the muscarinic cholinergic receptors is produced in the brain of manganese intoxicated mouse.

Animals↗

PubMed1990

[Pulmonary hydatid cyst. Presentation of a case].

One case of pulmonary hydatid cyst from Venezuela is reported. A 54-year-old man from Syria, was admitted to the hospital because of dyspnoea, fever and weight loss. A thoracic roentgenogram revealed a tumor in the basis of the left lung; a lobectomy was carried out. Histological study showed an unilocular hydatid cyst. The presence of scolices in alveoli and vessels suggest a probable dissemination of the parasite. Due to the rarity of the pulmonary hydatid cyst in Venezuela, the case is reported to call the attention about the existence of this pathology in the country, so that it can be diagnosed and treated correctly.

Echinococcosis, Pulmonary↗