Biomedical subjects

F Araya

Publications and source records attributed to F Araya.

At least 19 recordsLinked to original sources

PubMed2001

[Restless legs syndrome: a clinical study in adult general population and in uremic patients].

BACKGROUND: The restless legs syndrome (RLS) is a movement disorder characterized by an imperative urge to move the legs, associated with paraesthesias, motor restlessness and worsening of symptoms at night with at least partial relief by activity. Its prevalence ranges between 2-15% of general adult population and 20-30% of uremic patients. AIM: To evaluate the frequency and the clinical features of RLS in a sample of general adult population and in uremic patients, in Chile, correlating it with biochemical parameters. METHOD: 100 relatives of outpatients and 166 uremic patients undergoing chronic haemodialysis were interviewed assessing the presence and severity of RLS according to current diagnostic criteria. Biochemical parameters assessed were hematocrit, serum ferritin, phosphate, intact parathyroid hormone (iPTH) levels. RESULTS: 13% of the general population sample was affected, 15% of them were severe. Forty three cases were found among uremic patients (25.9%) (p < 0.01 vs general population), 60% of them were severe and women were affected with higher frequency (p < 0.05) and severity (p < 0.01). Four patients presented RLS even during hemodialysis. No correlation was found with biochemical parameters. Most RLS cases had not been diagnosed previously. CONCLUSIONS: In our population RLS is common and undetected. It is especially prevalent and severe in uremic patients: we found no evidence that anaemia, iron deficiency or iPTH level play a major pathogenic role. Our findings emphasize the need of greater medical awareness of RLS because available therapy may improve the quality of life.

Adolescent↗

PubMed2001

Tropical spastic paraparesis.

Human T-cell lymphotropic virus type I (HTLV-I) is the cause of endemic tropical spastic paraparesis (TSP) or HTLV-I-associated myelopathy (HAM). Because TSP/HAM is not a fatal disease, the neuropathology of this disease, albeit relatively well understood, is based on the examination of just a few incidental cases. We summarise our experience with the neuropathology of tropical spastic paraparesis/HTLV-I associated myelopathy (TSP/HAM). We studied three cases of TSP/HAM from different parts of the world. We demonstrated peculiar lamellated structures, called "multilamellar bodies" (MLB). It is tempting to suggest that MLB may represent specific ultrastructural markers of TSP/HAM. The pathology of the anteriorand posterior horns was similar and comprised axonal degeneration, accompanied by extensive astrocytic gliosis. Lymphocytic infiltration, particularly observed as "cuffs" around blood vessels, was scattered among other cellular elements. Ultrastructurally, myelin sheaths were relatively well preserved, and some demyelinated but not remyelinated fibres were observed. Moreover, axons with abnormal accumulations of neurofilaments, suggestive of axonal degeneration, were detected. Several axons contained Hirano bodies. In many samples glial processes replaced most of the remaining neuropil.

Ganglia, Spinal↗

PubMed1999

[Cerebral hemorrhage and angiopathy amyloid].

BACKGROUND: Cerebral amyloid angiopathy is considered pathogenic in non traumatic cerebral lobar hemorrhages. AIM: To study the frequency of cerebral amyloid angiopathy in brains of patients dying of non traumatic cerebral hemorrhages. MATERIAL AND METHODS: Thirty seven brains from patients, 25 men and aged 65 +/- 10 years old, with cerebral hemorrhages (14 lobar, 18 in basal ganglia and 5 in cerebellum or brainstem) were studied. As controls, the brains of 30 subjects, 14 men and aged 64 +/- 16 years old, dying of non neurological causes were studied. Deep and cortical vessels were stained with hematoxylin eosin, Gomori, Thioflavin T and Bodian. Definitive cerebral amyloid angiopathy was diagnosed when amyloid deposition was observed in the media of vessels. RESULTS: Twenty six out of 32 patients dying of cerebral hemorrhage and 3 of 21 controls had chronic hypertension. Cerebral amyloid angiopathy was present in 19 of 37 brains of patients with cerebral hemorrhage and 13 of 30 control brains. In patients with hypertension, vascular changes independent of the location and volume of amyloid deposition, were observed. Such changes were dilatation, tortuousness, thickening of walls specially in muscular and adventitia and hyaline degeneration. Thirteen brains with hemorrhage had fibrinoid necrosis and 10 had microaneurysms. CONCLUSIONS: In this series of patients, cerebral amyloid deposition was unspecific and its role in the pathogenesis of cerebral hemorrhages was not confirmed. Hypertension was associated with vascular degenerative changes that can lead to cerebral hemorrhages.

Aged↗

PubMed1999

Gelatinase activity of matrix metalloproteinases in the cerebrospinal fluid of various patient populations.

We have studied the enzymatic gelatinolytic activity of matrix metalloproteinases (MMPs) present in cerebrospinal fluid (CSF) of samples obtained from 67 individuals, twenty-one nonneurological patients (considered controls) and 46 subjects with various neurological disorders e.g., vascular lesions, demyelination, inflammatory, degenerative and prion diseases. Biochemical characterization of MMPs, a family of neutral proteolytic enzymes involved in extracellular matrix modeling, included determination of substrate specificity and Ca+2 dependency, as well as the effects of protease inactivators, carboxylic and His (histidine) residue modifiers, and antibiotics. Whereas all CSF samples expressed MMP-2 (gelatinase A) activity, it corresponded in most cases (normal and pathological samples) to its latent form (proenzyme; pMMP-2). In general, inflammatory neurological diseases (especially meningitis and neurocisticercosis) were associated with the presence of a second enzyme, MMP-9 (or gelatinase B). Whereas MMP-9 was found in the CSF of every tropical spastic paraparesis patient studied, its presence in samples from individuals with vascular lesions was uncommon. Patients blood-brain barrier damage was ascertained by determining total CSF protein content using both, the conventional polyacrylamide gel electrophoresis procedure under denaturing conditions and capillary zone electrophoresis.

Enzyme Activation↗

PubMed1999

[Intravenous tissue plasminogen activator in the treatment of acute ischemic stroke: feasibility, safety, and efficiency in the 2 first years of the clinical practice].

BACKGROUND: The only effective therapy for the treatment of acute ischemic stroke is the infusion of tissue plasminogen activator in the first three hours after the onset of symptoms. AIM: To report the experience with tissue plasminogen activator infusion in the treatment of acute ischemic stroke. PATIENTS AND METHODS: Ten males and 10 females, aged 52 to 85 years old with an acute ischemic stroke, admitted within 89 min after the onset of symptoms were studied. Tissue plasminogen activator was infused following the guidelines designed by the National Institute of Neurological Disorders and Stroke (NINDS). Patients were assessed according to Rankin scale after three months of follow up. RESULTS: All patients had normal CAT scans. The delay between the onset of symptoms and the infusion ranged from 75 to 180 min. One patient had a gastrointestinal bleeding due to a gastric ulcer and one patient had a fatal intracranial hemorrhage. After three months of follow up, 38% of patients had a good recuperation (Rankin 0 to 1), 33% had a mild to moderate disability (Rankin 2 or 3) and 14% had a moderate to severe disability (Rankin 4). There was a 15% mortality. CONCLUSIONS: This series show that treatment of acute ischemic stroke with tissue plasminogen activator is feasible and safe. The obtained results are similar to those reported abroad.

Acute Disease↗

PubMed1998

[Optic neuromyelitis: a necrotizing disease of the central nervous system].

Optic neuromyelitis is characterized by simultaneous or successive necrotizing lesions involving the optic nerves and the spinal cord. We report two females with the disease, aged 30 and 34 years old. In the latter, a neuropathological study was done. Both patients had clinical, neuroradiological and pathological features that differed from those of primary demyelinating syndromes such as multiple sclerosis. These patients illustrate the selectivity of optic nerve and spinal cord lesions. The latter involve mainly pyramidal and Goll tracts while, within the necrotizing lesions of the optic chiasma, the fibers of the unaffected optic nerve are spared. This pattern suggests a selective injury to some population of axons. Blood vessels were not affected in the necrotizing areas and the lesions did not follow a vascular territory, therefore a vascular mechanism causing the disease is unlikely. The clinical and neuropathological features of neuromyelitis optic suggest a selective involvement of some axons.

Adult↗

PubMed1997

Clinical and neuropathological study of six patients with spastic paraparesis associated with HTLV-I: an axomyelinic degeneration of the central nervous system.

Between 1990 to 1994, 6 TSP/HAM patients, 3 women and 3 men with an average age of 57.1 years (39 to 76 years old), who died in the Salvador Hospital were submitted to postmortem examination. The mean time of paraparesis was 7 years (3 to 17 years), and 2 patients had pseudobulbar signs. Three cases had macroscopic atrophy of the spinal cord. Histologically, all cases had lesions in the pyramidal tracts and 4 cases showed somatotopic lesions of the Goll's tracts which followed a "dying back" ascendant and descendant distribution, respectively. In 2 cases, both of which had intellectual impairment, demyelination of the subcortical and parathalamic areas was observed without U fiber involvement. Abnormal vessels with gross thickening of the adventitia, many of them with lymphocytic cuffs, were seen everywhere, especially in the spinal cord, brain stem, midbrain and meninges, but no relation between these findings and the parenchymal lesions was observed. Also, in the cases with posterior column involvement, neuronal changes and proliferation of satellite cells in the dorsal ganglia were found. All cases showed histological sialoadenitis and none had inflammatory muscle changes. We conclude that the lesions affected the neuraxis in a systemic axial fashion as in degenerative diseases, and did not seem to be secondary to vascular or inflammatory abnormalities.

Adult↗

PubMed1997

[Transient ischemic attacks in Chilean patients and their relationship with the country's pattern of cerebrovascular disease].

BACKGROUND: It has been postulated that in Chile, transient ischemic attacks (TIA) are much less frequent than in Caucasian populations. A lesser frequency of these attacks would be due to a higher frequency of intracranial atheromas, whereas an abundance of TIA would be a result of a higher prevalence of extracranial atheromas. AIM: To study the history of TIA in a group of Chilean patients with an acute episode of cerebrovascular disease. PATIENTS AND METHODS: One hundred forty nine patients admitted to a Neurology service of a public hospital in Santiago, with an acute stroke, were studied. Patients and close relatives were interrogated about previous symptoms of TIA using a structured questionnaire. RESULTS: One hundred nine patients had an ischemic and 40 patients a hemorrhagic stroke. Twenty patients with ischemic stroke had a history of TIA (18%). Fifteen out of 74 patients without a cardiac source of emboli (20%) and five out of 35 cases with an embolic source (14%) had a TIA preceding their stroke. Three out of 40 patients (8%) with hemorrhagic stroke had a history of TIA. CONCLUSIONS: This study does not support nor reject the hypothesis of a Chilean pattern of cerebrovascular disease unlike that found in Northern Caucasians.

Acute Disease↗

PubMed1997

[Copper intake and blood levels as risk factors for atheromatous disease].

BACKGROUND: Copper is part of antioxidant enzymes and could have a cardiovascular protective effect. A higher cardiovascular risk has been associated with high as well as low plasma copper levels. AIM: To search for differences in copper intake and plasma levels between patients with coronary artery or cerebrovascular diseases and normal subjects. PATIENTS AND METHODS: Zinc and copper intake, plasma levels and serum lipid levels were measured in 20 patients with cerebrovascular disease, 20 patients with an acute myocardial infarction and 40 subjects hospitalized for elective surgery, that served as controls. RESULTS: Copper and zinc intake was below recommended allowances in all subjects. Serum zinc and copper levels did not differ in the three study groups. In patients with myocardial infarction a weak correlation was found between serum copper and total cholesterol (r = 0.24; p < 0.05) and LDL cholesterol (r = 0.31; p < 0.05). CONCLUSIONS: No differences in copper levels were found in subjects with atherosclerosis and controls. The correlation between serum copper and cholesterol deserves further investigation.

Aged↗

PubMed1996

[Somatosensory evoked potentials and symptomatic response to dopaminergic drugs in Parkinson's disease].

Short latency somatosensory evoked potentials were measured in 10 patients with Parkinson's disease before and after the administration of Apomorphine 5 mg sc. Eight of these subjects were reassessed after one month of treatment with Levo-Dopa. These potentials were measured in other nine subjects before and after one month of treatment with Selegiline 10 mg od. There was a significant increase of frontal potential N30 in nine of 10 subjects that received apomorphine, in seven of eight patients treated with Levo-dopa and seven of nine patients treated with Selegiline. No changes in N20 parietal potential were observed. During apomorphine test, changes in N30 potential preceded clinical improvement in six patients and occurred simultaneously in three patients. No changes with apomorphine in N30 potential were observed in two healthy males. There was no relationship between electrophysiological changes and duration of disease or motor fluctuations. It is concluded that short latency somatosensory evoked potentials are an objective means of measuring dopaminergic response in patients with Parkinson's disease.

Adult↗

PubMed1995

HTLV-I positive progressive spastic paraparesis (TSP) associated with a lymphoid disorder in three Chilean patients.

We describe the clinical and laboratory features in three Caucasian Chilean patients with tropical spastic paraparesis (TSP) associated with/or preceded by a lymphoproliferative disorder involving cutaneous lesions and localised lymphadenopathy. The neurological symptoms and signs were characteristic of TSP and CSF examination revealed the presence of oligoclonal bands. All three patients had a moderate leucocytosis (10-14 x 10(9)/l) with eosinophilia and a minority (2-4%) of circulating atypical polylobed or ATLL-like lymphocytes. Lymph node histology showed a diffuse pattern of infiltration (1 case) and marked expansion of the paracortical zone with convoluted lymphocytes and immunoblasts (2 cases). Skin biopsy demonstrated a dermal lymphoid infiltration with epidermotropism. Antibodies to HTLV-I were detected in the serum and CSF in the three patients and Southern blot analysis of peripheral blood mononuclear cells showed a monoclonal integration of HTLV-I proviral DNA in one case whereas in the two others the pattern was indicative of low level polyclonal integration. All three patients were treated with prednisolone and one with PUVA with transient partial response on the skin and neurological manifestations. Two patients died months to 5 years from presentation and the other is alive 12 years from diagnosis with active neurological and skin disease. The simultaneous occurrence of HTLV-I associated TSP with smouldering ATLL and a cutaneous ATLL or pre-leukaemic form is discussed.

Adult↗

PubMed1995

[Validation of a screening instrument for studying the prevalence of cerebrovascular diseases in the Chilean population].

We assessed a screening instrument, adapted from a model suggested by WHO, aimed to perform population studies on the prevalence of cerebrovascular disease in Chile. Sixty-two subjects, 31 with cerebrovascular diseases and 31 without, were asked about symptoms and requested to do simple movements by trained interviewers. The results of the instrument were compared with a neurological examination performed by two specialists. Global sensitivity and specificity of the instrument, using WHO evaluation criteria, were 100 and 38.7% respectively. When three or more symptoms and one positive sign were considered as cutoff points, global specificity increased to 61% and sensitivity decreased to 93%. It is concluded that the present instrument is highly sensitive but lacks specificity.

Aged↗

PubMed1994

[Dissection of vertebral artery: report of a case and review of the literature].

Vertebral artery dissection seems to be a frequent cause of stroke in young adults. We report a 34 years old female that suffered a cardiac arrest while practicing aerobics, with complete recovery and four months later developed an acute Wallenberg's syndrome. Magnetic resonance imaging showed an infarction in the right posterolateral medulla oblongata and in the right cerebellar hemisphere. Angiography revealed an occlusion of the third segment (V3) of the right vertebral artery which was hypoplastic. The patient was anticoagulated with a favorable clinical outcome. A follow up angiography, performed six months later, showed an incomplete recanalization of the vessel. Vertebral artery dissection should be suspected in every patient with ischemic symptoms or signs related to the vertebrobasilar territory, specially in young or middle aged patients with a history of trauma. Magnetic resonance imaging and ultrasound-doppler examinations are the diagnostic test of choice.

Adult↗

PubMed1993

Southernmost carriers of HTLV-I/II in the world.

To clarify the real distribution of HTLV-I and -II carriers among indigenous people in central and South America, blood samples collected from indigenous people in isolated regions of Southern Chile were examined. Among 199 inhabitants from Chiloe Island and Pitrufquen town, three cases (1.5%) showed positive anti-HTLV-I antibodies. Two out of the three (82-year-old male and 58-year-old female) reacted to HTLV-II-specific Gag and/or Env proteins but not to HTLV-I-specific ones. The latter case was confirmed as an HTLV-II carrier by polymerase chain reaction test.

Aged↗

PubMed1993

[Preliminary study of HTLV-I seroprevalence in Chilean Indian populations].

Aiming to seek the origin and define the prevalence of HTLV-1 infections, 464 blood samples from aboriginal populations proceeding from isolated regions of the north and south of Chile were studied. Antibodies against HTLV were measured with agglutination tests and confirmed with immuno-fluorescence and Western Blotting. Seven out of 107 (6.5%) blood samples from Atacama indians, 2 out of 202 (1%) from Mapuche indians and 3 out of 155 (1.9%) from Huilliche aborigines were positive. These results highlight an important presence of the virus in indigenous populations, specially in the extremes of the country. These findings could suggest an indigenous (mongoloid) origin of HTLV-1 in Chile, specially in Chiloe, where apparently there has been no contact with african or japanese populations, that could be the origin of the contamination.

Adolescent↗

PubMed1992

Progressive spastic paraparesis associated with human T-cell leukemia virus type I (HTLV-I).

Patients with progressive spastic paraparesis (PSP), commonly middle-aged women, are distributed throughout the country of Chile. During the three years from 1987 to 1990, we collected 83 cases of PSP from among 225 patients with various neurological diseases. The clinical picture was of a bilateral pyramidal syndrome, with sensory deficits in only 15.5% of the cases, and a slow illness progression in the majority of them. In patients with PSP, antibody to human T-cell leukemia virus type I (HTLV-I) was analyzed by enzyme linked immunosorbent assay (ELISA) and confirmed by western blot analysis. Forty-five (54.2%) patients were anti-HTLV-I antibody positive in cerebrospinal fluid (CSF) and peripheral blood. Among them, 2 patients had leukemia/lymphoma and one had Sjögren syndrome. In the laboratory study of seropositive PSP, mononuclear pleocytosis was found in 35.7%; there was an abnormal increase of the IgG index in 66.6% and an increase in CD2 in blood and CSF, and CD4 in blood. A delayed latency of somatosensory evoked potentials was observed in 90.9%. The neuropsychological study revealed a WAIS with a mean verbal IQ of 80.7 and a mean performance IQ of 84.8. The most impaired items were digit symbol and digit span. Seven subjects (18.9%) with anti-HTLV-I antibody were found among 37 relatives from 19 anti-HTLV-I positive cases of PSP.

Adult↗

PubMed1992

[HTLV-I clinical pathological spectrum].

HTLV-I has been revealed as the etiological factor of the Tropical Spastic Paraparesis (TSP) and of the T-cell leukemia-lymphoma of the adult (ATLL). Recently, it has also been associated to some forms of polymyositis, polyarthritis, polyneuropathies, Sjögren's syndrome, thrombocytopenia and lympho-alveolitis. The clinical and pathological spectrum of this retrovirus is analyzed taking into account the Chilean cases and those reported by the international medical literature.

Arthritis, Infectious↗

PubMed1991

Evoked potential abnormalities in progressive spastic paraparesis associated to HTLV-1.

The electrophysiological features of progressive spastic paraparesis (PSP) associated with HTLV-1 in Chile, a non-tropical country, are presented. Twenty-two of 45 PSP subjects were positive for HTLV-1 antibodies. Trimodal evoked potentials were all normal in only 2 of these cases (9.1%). Somatosensory evoked potentials (SSEPs) were abnormal in 19 patients (86.3%) with a mean amplitude of 1.31 uV SD 0.92. Visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) were normal in all patients except four. Peripheral nerve conduction was normal in all but one who showed discrete slowness of the motor conduction velocity in the peroneal nerves. EMG was normal in 15 cases in whom it was performed. SSEP's were abnormal in 2 (8.7%) of 23 HTLV-1 negative cases with a mean amplitude of 2.4 uV SD 1.5, which is statistically different with respect to the positive cases (p less than 0.001). These results support an involvement of the spinal cord not restricted to the pyramidal tracts but also including subclinical damage of the posterior columns in PSP associated to HTLV-1.

Adult↗