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Biomedical subjects

H Ríos

Publications and source records attributed to H Ríos.

At least 19 recordsLinked to original sources
PubMed2003

[Helicobacter pylori seroprevalence in dialysis patients].

AIM: (a) to establish Hp infection seroprevalence among patients under chronic dialysis and to compare it with that of general population, (b) to assess the relationship between Hp prevalence and parameters associated with a higher morbidity, such as serum albumin levels, dialysis adequacy, and quality of life in this population. METHODS: Ninety-three consecutive patients of both genders (58 M/35 F), X 57.5 +/- 17.2 years old, with end-stage chronic renal failure on maintenance dialysis were included. All of them received dialysis at Hospital Italiano, Buenos Aires. The presence of anti-Hp antibodies was established and its prevalence was compared with a control group. In all cases, serum albumin levels and time in dialysis were determined. In addition, dialysis adequacy was established by KT/V and quality of life was measured with Karnofsky's index. Patients and controls were matched according variables associated with Hp infection in our country, i.e., age, socioeconomic and education levels. RESULTS: Ninety-three dialysis patients were matched with 93 controls. According to the quick serological test, 44 out of 93 (47.3%) dialyzed patients and 55 out of 93 (53.6%) controls were Hp positive (ns). Forty-one out of 76 patients (53.9%) with a serum albumin level 3.5 g/dl and 3/17 (17.6%) with a serum albumin level < 3.5 g/dl were anti-Hp positive (odds ratio, 0.06; 95% CI, 0.01-0.39; p < 0.01). Fifty-five out of 80 patients (69.2%) with Kt/V > 1.2 and 6/13 (43.8%) with Kt/V 1.2 Pounds were anti-Hp positive (odds ratio, 0.10; 95% CI, 0.02-0.65; p < 0.05). Four out of 15 patients (26.7%) with Karnofsky's index > 70, and 40/78 (51.3%) with Karnofsky's index < or = 70 were anti-Hp positive (odds ratio, 0.37; 95% CI, 0.06-2.95, p = 0.26). CONCLUSION: According to our results, dialysis patients do no represent a high-risk group of Hp infection. Those individuals with higher morbidity and mortality rates as evidenced by low serum albumin levels or by a low Kt/V have a lower Hp prevalence, perhaps due to a poor immune response o due to the use of antibiotics. Therefore, Hp infection screening en dialysis units does not differ from the guidelines developed in Maastrich for the general population.

Argentina↗
PubMed2001

Motor, cytoarchitectural and biochemical assessment of pharmacological neuroprotection against CNS damage induced by neonatal exposure to ionizing radiation.

Exposure of neonatal rats to a 5 Gy single dose of X-irradiation induces permanent abnormalities in cerebellar cortex cytoarchitecture and neurochemistry and motor function. This rodent model constitutes an useful tool to evaluate morphological, neurochemical and motor changes induced by ionizing radiation and the possible restorative effects of potential or clearly established neuroprotective drugs. After selection and administration of a neuroprotective agent to neonatally irradiated rats, quantitative evaluations of motor behavior (gait), cerebellar cortex cytoarchitecture and cerebellar monoamine levels are performed. Data are compared to those of both saline-injected, X-irradiated, and saline-injected, sham-irradiated controls. Evaluation of data from the different experimental groups is performed at postnatal days 30 and 90. After this postnatal interval, radiation-induced damage of cerebellar function in nonprotected rodents is considered to be permanent. The longitudinal evaluation of various parameters in the different experimental groups through a multidisciplinary approach, allows determination of the variables that are more sensitive to X-irradiation-induced damage and/or neuroprotective agent-induced restoration. Given the well-known correspondence in cerebellar developmental stages between rodents and humans, this model and related studies bring health-related implications, considering the accidental or therapeutic exposure of developing human beings to ionizing radiation.

Animals↗
PubMed2000

Development of nitric oxide neurons in the chick embryo retina.

Nitric oxide (NO) is a gas involved in neurotransmission in the central nervous system (CNS) and in vertebrate retinas. This paper describes five types of nitrergic neurons in developing and adult chick retina using the nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) reaction. Three of them, nitrergic types 1, 2 and 3, were observed in the inner nuclear layer, while nitrergic type 4 was observed in the ganglion cell layer; nitrergic type 5 were the retinal photoreceptors. Cell processes formed four nitrergic networks, which could be observed in the inner plexiform layer (IPL), at sublayers 1, 3a, 3b and 4. Another nitrergic network was observed in the outer plexiform layer (OPL). From hatching, the dendritic branches were completely developed in the IPL and in the OPL, forming the mentioned networks. Current evidence suggests that NO is coexpressed with other neurotransmitters in neurons of the CNS. Double-staining procedures, using NADPHd and 5HT immunohistochemistry in chicken retina, in a sequential or in an alternative manner, did not reveal the coexistence of these two neurotransmitters in the same neurons, but their networks matched in sublayers 1 and 4 of the IPL.

Animals↗
PubMed2000

GM1 ganglioside treatment protects against long-term neurotoxic effects of neonatal X-irradiation on cerebellar cortex cytoarchitecture and motor function.

Exposure of neonatal rats to a 5 Gy dose of X-irradiation induces permanent abnormalities in cerebellar cortex cytoarchitecture (disarrangement of Purkinje cells, reduction of thickness of granular cortex) and neurochemistry (late increase in noradrenaline levels), and motor function (ataxic gait). The neuroprotective effects of gangliosides have been demonstrated using a variety of CNS injuries, including mechanical, electrolytic, neurotoxic, ischemic, and surgical lesions. Here, we evaluated whether systemically administered GM1 ganglioside protects against the long-term CNS abnormalities induced by a single exposure to ionizing radiation in the early post-natal period. Thus, neonatal rats were exposed to 5 Gy X-irradiation, and subcutaneously injected with one dose (30 mg/kg weight) of GM1 on h after exposure followed by three daily doses. Both at post-natal days 30 and 90, gait and cerebellar cytoarchitecture in X-irradiated rats were significantly impaired when compared to age-matched controls. By contrast, both at post-natal days 30 and 90, gait in X-irradiated rats that were treated with GM1 was not significantly different from that in non-irradiated animals. Furthermore, at post-natal day 90, cerebellar cytoarchitecture was still well preserved in GM1-treated, X-irradiated animals. GM1 failed to modify the radiation-induced increase in cerebellar noradrenaline levels. Present data indicate that exogenous GM1, repeatedly administered after neonatal X-irradiation, produces a long-term radioprotection, demonstrated at both cytoarchitectural and motor levels.

Animals↗
PubMed2000

Chronic corticosterone impairs inhibitory avoidance in rats: possible link with atrophy of hippocampal CA3 neurons.

The aim of our work was to evaluate the effect of a chronic (22 days) administration of corticosterone, which induces supraphysiological serum levels of the hormone, on an inhibitory avoidance learning in rats (one-trial step-through learning task, footshock: 0.5 mA, 2 s). We also studied hippocampal markers of neuroanatomical CA3 pyramidal neuron atrophy by using the Golgi staining method. Chronic exposure to high CORT serum levels induced a significant impairment of inhibitory avoidance learning. The CORT group also showed hippocampal glucocorticoid receptor (GR) downregulation and the decrease of hippocampal CA3 branch points and total dendritic length in the apical tree that would be causally related with the learning impairment.

Adrenal Glands↗
PubMed2000

Oral ciprofloxacin after a short course of intravenous ciprofloxacin in the treatment of spontaneous bacterial peritonitis: results of a multicenter, randomized study.

BACKGROUND/AIMS: Oral quinolones have been suggested as treatment of cirrhotic patients with uncomplicated spontaneous bacterial peritonitis. To evaluate the efficacy of oral quinolones in all patients with this complication, oral ciprofloxacin after a short course of intravenous (i.v.) ciprofloxacin was compared to i.v. ciprofloxacin. METHODS: Eighty patients were allocated to receive ciprofloxacin i.v. 200 mg/12 h for 7 days (group A, n= 40) or i.v. 200 mg/12 h during 2 days followed by oral 500 mg/12 h for 5 days (group B, n=40). All patients with spontaneous bacterial peritonitis admitted to the hospital were included. Twenty-five variables obtained 48 h after treatment were introduced into univariate and multivariate analyses to identify predictors of survival and outcome. RESULTS: In the baseline condition, no differences were found between the two groups in clinical data, hepatic and renal function tests and Child Pugh score. The infection resolution rate was 76.3 % in group A and 78.4 % in group B, and hospital survival was 77.5% in both groups. In multivariate analysis serum creatinine and serum leukocytes 48 h after treatment were associated with prognosis. CONCLUSIONS: Oral ciprofloxacin after a short course of i.v. ciprofloxacin is effective in the treatment of spontaneous bacterial peritonitis. This regimen can be applied to all patients admitted to the hospital with this complication, and could be an alternative to treating these patients as outpatients.

Administration, Oral↗
PubMed2000

Prevalence of Helicobacter pylori infection in Argentina: results of a nationwide epidemiologic study. Argentinean Hp Epidemiologic Study Group.

Our aim was to assess the prevalence of Helicobacter pylori (Hp) infection in Argentina, in the general population and by age groups, and to determine the value of various epidemiologic variables as predictors of Hp infection. The study comprised 754 subjects (443 women 158.7%], 311 men [41.3%]) from both genders, consecutively recruited from health centers where patients were undergoing routine medical analyses. Average age was 32 +/- 22 years. The pediatric group included subjects < or =18 years of age (n = 261). Stratification was based primarily on climatic factors and secondarily on sanitary and demographic considerations. Hp infection status was assessed through a quick serologic test. The overall Hp infection prevalence in Argentina was 35.7 +/- 3.8%. The age was statistically significant using a multiple regression test (p < 0.01). Furthermore, the socioeconomic (p < 0.05) and educational level (0 < 0.01) in the adults and the water sources (p < 0.01) in the pediatric group were all statistically significant according the multiple regression test. The overall Hp infection prevalence in Argentina was 35.7 +/- 3.8%. Age was a predictor of Hp infection status. There is evidence of low infection prevalence in children. a higher prevalence in adolescents, and a more noticeable increase at 40 years of age. Furthermore, the socioeconomic and educational level in adults and the water sources in the pediatric group explained, in part, the occurrence of Hp infection.

Adolescent↗
PubMed1997

Development of serotoninergic chick retinal neurons.

Numerous neurotransmitters have been studied in detail in the developing retina. Almost all known neurotransmitters and neuromodulators were demonstrated in vertebrate retinas using formaldehyde-induced fluorescence, uptake autoradiography or immunohistochemistry procedures. Serotoninergic (5HT) amacrine neurons were described in the inner nuclear layer (INL) of the retina with their dendrites spreading within the inner plexiform layer (IPL). The present work describes the morphological pattern of development of serotoninergic amacrine neurons with a stratified dendritic branching pattern in the chick retina from embryonic day 12 to postnatal day 7. Serotoninergic-bipolar neurons are also described. SHT-amacrine neurons have round or pear-shaped somata and primary dendritic trees oriented toward the IPL that runs through the INL, showing several varicosities. Secondary dendrites then go through the INL, without any collateral branch. At the outer and inner margin of the IPL the primary and secondary dendrites originate an outer and an inner serotoninergic network, respectively. When the primary dendritic tree reaches the IPL it deflects laterally in sublayer 1-the outer serotoninergic network. Tertiary branches then arise from the secondary dendrite and deflect in the innermost sublayer of the IPL-the inner serotoninergic network. The final pattern of branching of 5HT amacrine cells was present at embryonic day 14 and was completely developed at hatching. Serotoninergic (5HT) bipolar neurons were also present in the INL at hatching. They are weakly immunoreactive and are probably a subset of bipolar cells that accumulate serotonin from the intersynaptic cleft and are not "true" 5HT neurons.

Animals↗
PubMed1997

Differential staining of two subpopulations of Purkinje neurons in rat cerebellum with acid dyes.

We present a new method that stains differently two subpopulations of Purkinje cells in the adult rat. Deparaffinized sections of cerebella, fixed by perfusion with buffered glutaraldehyde or Bouin's fluid were stained with 0.5% light green in 50% ethanol (10-30 min). The excess dye was removed with saturated aqueous picric acid (10-30 min). At this point some Purkinje cells appeared as lightly stained neurons, while others were strongly stained. Slides were immersed in 0.5% aqueous acid fuchsin for approximately 1 min until the lightly stained neurons acquired a red color. Following immersion in 1% phosphotungstic acid, slides were rapidly dehydrated in ethanol, passed to xylene and mounted in Canada balsam. Two subpopulations of Purkinje cells differing in their protein content in somata and proximal dendrites stained differentially by this method. They occurred in all coronal and sagittal sections and in patches or stripes. Their relative proportion varied from lobule to lobule. A second staining method used potassium permanganate as the sole staining reagent. The staining reagent can be used on sections previously stained with the acid dyes. Purkinje cells appeared as subsets of brownish to deep brown stained neurons, the latter ones corresponding to green stained cells in the dichromic method. The results obtained indicated that the subpopulations reflect real differences among individual neurons and are not artifacts. The technique holds promise for identifying and localizing sub-sets of Purkinje cells differing in their protein content under normal and experimental conditions and for their further characterization by combined staining and histochemical procedures.

Animals↗
PubMed1993

Motor abnormalities and changes in the noradrenaline content and the cytoarchitecture of developing cerebellum following X-irradiation at birth.

We have studied the developmental time-course of changes in the noradrenaline (NA) content of cerebellum (CE), cytoarchitecture of the cerebellar cortex, and motor abnormalities induced by the exposure of the cephalic end of rats to a single dose (5 Gy) of X-irradiation immediately after birth. At all ages examined, i.e., from postnatal (PN) d 5 to 90, CE from exposed animals show a marked atrophy, with an agranular cortex that has lost its layered structure. Purkinje cells are scattered at all depths in the cortex, and their primary dendrite is randomly oriented. The motor syndrome includes dystonia-like movements, a fine tremor, and an ataxic gait. Being progressive, the abnormal movements are evident from PN d 10, and fully developed by d 30. On the other hand, no differences in cerebellar NA content between X-irradiated rats and age-matched nonirradiated controls were detected from PN d 5 to 60. However, at PN d 90 a significant increase in NA content of CE from exposed animals is found when compared to either age-matched controls (+36%, p < 0.01), or data from irradiated rats obtained at PN d 5 to 60 (p < 0.01). These results indicate a temporal dissociation between the motor and cytoarchitectural abnormalities and the increase in cerebellar NA content produced by a single dose of X-rays at birth. The late increase in cerebellar NA content might represent a compensatory response of noradrenergic terminals to an altered information flow out of the cerebellar cortex induced by the ionizing noxa.

Animals↗
PubMed1990

[Perspectives of liver transplantation in Chile].

After an initial experience with 4 patients who received orthotopic liver transplant (OLT) we analyze the perspectives of establishing liver transplantation programs in Chile. An estimated 100 adult and pediatric patients require OLT a year and no more than 3 centers are required to deal with this and acquire experience with the procedure. A national organization for organ procurement is essential, given the marked difficulties in obtaining cadaver organs at present. Each procedure has an estimated cost of $5 million with 2 more millions in the first year. Thus a program for 15 patients a year may cost $ 100 million, personnel expenses not included.

Adult↗
PubMed1987

Effects of light- and dark-rearing on the postnatal development of GABA receptor sites in the chick optic lobe.

To investigate the ability of GABA receptor sites to undergo environmental-dependent plastic changes, the postnatal developmental pattern of GABA receptors was studied under different levels of light stimulation, i.e. normal-, light- and dark-rearing. At hatching the specific binding of [3H]GABA was 1.74 +/- 0.36 pmol/optic lobe. In normally reared chicks the number of GABA binding sites showed a transient increase with the highest value at the 6th day (7.0 +/- 1.32 pmol/optic lobe). This value is higher than the one reached at the adult stage. Between the 3rd and 6th day, there was a 33.7% increase in specific [3H]GABA binding in light-reared compared with normally reared animals (P less than 0.05). In the dark-reared chicks, the specific binding was 36.4% lower than that found in normally reared (P less than 0.02). However, the changes in receptor density were transient since at the 17th day the number of GABA binding sites returned to adult levels. Scatchard analysis revealed that the differences observed in the high affinity GABA binding sites between the three groups were due to modifications in the total number of binding sites while the affinity remained unchanged. The maximal number of binding sites were: 2.71, 7.01 and 1.79 pmol/mg protein in normally, light- and dark-reared chicks, respectively; while the apparent dissociation constants were unaffected: 3.2, 3.4 and 3.6 nM, respectively. These results show that, during postnatal development, different conditions of visual experience produce synaptic changes at the molecular level. These changes probably occur within a period of high plasticity, prior to the end of a critical period.

Aging↗
PubMedDate not supplied

Increased activity of tyrosine hydroxylase in the cerebellum of the X-irradiated dystonic rat.

The exposure of the cephalic end of rats to repeated doses of X-irradiation (150 rad) immediately after birth induces a long-term increase in the noradrenaline (NA) content of cerebellum (CE) (+ 37.8%), and a decrease in cerebellar weight (65.2% of controls), which results in an increased NA concentration (+ 109%). This increase in the neurotransmitter level is accompanied by a dystonic syndrome and histological abnormalities: Purkinje cells (the target cells for NA afferents to CE) fail to arrange in a characteristic monolayer, and their primary dendritic tree appears randomly oriented. The injection of reserpine 0.9 and 1.2 mg/kg ip to adult rats for 18 h depletes cerebellar NA content in both controls (15.7 +/- 4 ng/CE and 2.8 +/- 1.5 ng/CE, respectively) and X-irradiated rats (17.1 +/- 1 ng/CE and 8.3 +/- 2 ng/CE, respectively). The activity of tyrosine hydroxylase (TH) in CE of adult rats, measured by an in vitro assay, is significantly increased in neonatally X-irradiated animals when compared to age-matched controls (16.4 +/- 1.4 vs 6.32 +/- 0.6 nmol CO2/h/mg prot., p less than 0.01). As observed for NA levels, a net increase in TH activity induced by the ionizing radiation is also measured: 308.9 +/- 23.8 vs 408.2 +/- 21.5 nmol CO2/h/CE, p less than 0.01 (controls and X-treated, respectively). These results suggest that X-irradiation at birth may induce an abnormal sprouting of noradrenergic afferents to CE. The possibility that these changes represent a response of the NA system to the dystonic syndrome is discussed.

Afferent Pathways↗
PubMedDate not supplied

Validation of defining characteristics of four nursing diagnoses using a computerized data base.

As the use of nursing diagnoses in clinical practice increases, systematic research is necessary to appropriately validate them. Validity studies could be expedited by the use of information technology and computerized clinical data bases. The purpose of the following descriptive study was to validate the defining characteristics (risk factors for potential diagnoses) of the four nursing diagnoses related to alterations in fluid volume proposed by the North American Nursing Diagnosis Association using a nursing minimum data set (NMDS) collected from a computerized nursing data base. A sensitivity measure, the proportion of subjects with specific defining characteristics for a given diagnosis among the total number of subjects with the respective diagnosis, was used to estimate validity. The study was conducted in a 265-bed, mid-western, community hospital in which computerized nursing diagnosis care planning is used. The elements of the NMDS and defining characteristics were collected from a systematic sample (N = 191). The sample consisted of a proportion of about half of computerized discharge patient care plan summaries from each of the four diagnostic labels related to alteration in fluid volume obtained from medical records during the 1987 calendar year. Discharge patient care plan summaries contained at least one of four nursing diagnoses related to alteration in fluid volume. The results show the existence of individual defining characteristics as well as combinations of defining characteristics meeting validation criteria for each diagnostic label. Never-documented defining characteristics also were identified.

Adolescent↗