Biomedical subjects
Publications and source records attributed to A Rojas.
Ratibinolide II, a new eudesmanolide, and the known flavanone hispidulin have been isolated from Ratibida latipalearis. The structure elucidation of the new compound was unequivocally established by spectral and X-ray crystallographic analyses.
A panoramic sight of epidemiological, clinical and experimental studies, referring to Loxosceles laeta and loxoscelism, carried out in 1955-1988, in Santiago, Chile is presented. Two-hundred and sixteen cases of loxoscelism were studied. The most relevant features were: 84.3% corresponded to cutaneous loxoscelism (CL) and 15.7% to viscerocutaneous loxoscelism (VCL); 73.6% occurred in hot season; in 86.6% of cases the accident happened in the house, particularly in bedrooms, while the people were sleeping or dressing. The spider was seen in 60.2% of cases and identified in the laboratory as L. laeta in 10.6% of all cases. The sites more frequently bitten were the limbs with 67.6%; a burning-stinging was the most frequent initial symptom. Pain, edema and livedoid plaque, which developed later into a necrotic eschar, were the predominant local manifestations. In VCL, hematuria and hemoglobinuria were constant, while jaundice, fever and sensorial involvement were present in most of the cases. CL patients were parenterally treated with antihistaminic drugs or corticoids, while VCL ones were treated with corticoids by injection. The condition of patients in the last follow up was: complete cure in 75.5%, cure with a scarfed sequela in 8.3%, death in 3.7% (all VCL) and abandonment in 12.5%. Additionally, a series of experimental studies, both in vivo and in vitro, has been performed in order to clarify basic aspects on L. laeta venom and the treatment of loxoscelism.
A series of already published and unpublished seroepidemiological surveys for toxoplasmosis, carried out in Chile in 1982-1994, is reviewed, expanded and analyzed. The surveys included 76,317 apparently healthy individuals of different ages (0.57% of the country's total population), from 309 urban and rural-periurban localities. Urban groups were integrated by blood donors, delivering mothers and middle grade schoolchildren, while rural-periurban individuals corresponded to unselected family groups. Blood samples were collected in filter paper. The presence of antibodies to Toxoplasma gondii was determined by the indirect hemagglutination test (IHAT), titers > or = 16 were considered positive. The test resulted positive in 28,124 (36.9%) of the surveyed people. Two hundred and six (0.3%) individuals presented IHAT titers > or = 1000, probably corresponding to acute or reactivated infections. A progressive increase of positive IHAT from northern to southern regions of the country was noted, phenomenon probably related to geographical conditions and to a higher production and consumption of different types of meat in the latter regions. It is postulated that ingestion of T gondii cysts by humans is epidemiologically as important as ingestion of oocysts. The result presented stress the epidemiological importance of toxoplasmosis in humans, and warn about eventual implications in immunocompromised patients and in transplacental transmission, organ transplants and transfusions.
Congenital Chagas disease (CChD) has been reported in different countries, mostly in Latin America. In 1987 a fatal case of CChD of second generation (CChDSG) was published. Within a period of six months--1989-1990--two cases of CChDSG were diagnosed and studied in the city of Santiago. Two premature newborns, sons of two sisters, with moderate liver and spleen enlargement, were found to have positive serology for Chagas disease and xenodiagnoses. The mothers, urban residents all their lives, without antecedents of triatomine bugs contact or blood transfusions, showed positive serology and xenodiagnoses. Their mother (grandmother of the infants), lived 20 years in a Northern rural Chagas disease endemic locality, in a triatomine infested house. Afterwards, she moved to Santiago, where she married and has resided up to now. Serology and xenodiagnoses were also positive. All the Trypanosoma cruzi infected individuals were successfully treated with nifurtimox.
Esthetically compromised or nonrestorable implants present major clinical problems. Of 3,850 implants placed, 10 osseointegrated implants in 6 patients were surgically repositioned using maxillary or mandibular osteotomies and rigidly fixated, under intravenous sedation. The segments were predictably changed in a vertical, anteroposterior, transverse, or axial inclination manner. Excellent healing of bone and soft tissue was observed. This simple, reliable technique allowed these 10 implants to be esthetically and functionally restored with permanent prostheses.
During 1997 a seroepidemiological study on Chagas' disease was carried out in 18 localities of three provinces (Tocopilla, El Loa and Antofagasta) of Region II (20 degrees 56'-26 degrees South Lat.; 70 degrees 38'-67 degrees West Long.), in order to assess the impact of the control program against Triatoma infestans launched in 1988, based on insecticide spraying of dwellings. By means of ELISA and an indirect hemagglutination test for Chagas' disease blood samples from 1,034 children under 10 years of age were examined, arising a 0.5% (3 cases) positivity. Test resulted positive in 2 (0.9%) children from the locality of San Pedro de Atacama and 1 (0.4%) from Calama city, all in the age group 6-10 year-old. However, none of their dwellings were found infested with T. infestants. These results indicate that the control program has a good possibility to prevent new human infections. It is advisable to continue the seroepidemiological and entomological vigilance and remark the necessity of increasing the effort in the study of transmission through other routes, to adopt or reinforce the pertinent preventive measures.
A 2-5 years follow-up of parasitemia, by the use of xenodiagnosis (XD) was carried out in nine patients with chronic T. cruzi infection who proceeded from chagasic endemic areas of Chile. The patients (mean age 55 years) were hospitalized in the chronic section of a psychiatry institution sited in a permanent triatomines free urban area. Clinical examination, X-rays images (cardiovascular, esophagus and colon) and electrocardiogram resulted normal in all the patients. Basic study unit of parasitemia was a XD box which contained 7 nymphs III of Triatoma infestans which was used in a serial XD consisting in the simultaneous application of a pair of boxes a day during three consecutive days, making a total of six boxes (42 nymphs). The minimal time of duration of infection (M.D.I.) for each patient was estimated that this was adquired close to hospitalization. The M.D.I. varied between 6 and 45 years. The global positivity of XD boxes ranged between 6.3 and 84.7%, being in three patients lower than 12% and in six patients higher than 52%. In considering the yield of XD it is important to stress that during all the study of the nine patients with chronic chagasic infection 1282 XD boxes were applied resulting positive 582 (45.4%). At the end of the follow-up all patients received specific treatment for chagasic infection with nifurtimox at the daily dose of 10 mg/kg of body weight during 60 days. According to the result, two main conclusions arise: 1.--Serial XD has a high efficiency for detecting, evaluate and evolve parasitemia in patients with chronic chagasic infection. 2.--Parasitemia may present low, medium or high levels in different individuals and has a variable and fluctuating character.
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OBJECTIVE: Estrogens have a potent antioxidant effect on low-density lipoprotein (LDL) cholesterol in vitro and in vivo. A variety of compounds with antioxidant properties, such as vitamins and other hormones, also have been recommended in clinical practice to prevent several diseases related to oxidation. The aim of this study was to compare the antioxidant potency of estradiol (E2), the liposoluble vitamin E (both, alpha- and gamma-tocopherol), and melatonin. DESIGN: LDL was isolated by ultracentrifugation from the plasma of 11 healthy, untreated postmenopausal women. Aliquots containing 0.5 mg of LDL protein were incubated for 4 h with 15 microM of CuSO4 to induce oxidative stress and with one of the four compounds studied: E2, alpha-tocopherol, gamma-tocopherol, or melatonin in doses of 0, 5, 15, 50, and 500 microM and 1 and 2 mM. Malondialdehyde (MDA) was measured as a marker of LDL oxidation. RESULTS: E2 induced a dose-dependent decrease in MDA concentration (nmol/mg protein). MDA values were significantly different as compared with baseline at 5 microM of E2 (F = 47.17; p < 0.0001). Alpha-tocopherol, gamma-tocopherol, and melatonin also showed a significant decrease in MDA concentration but to a lesser degree. The reduction of MDA reached statistical significance at 50 microM with alpha-tocopherol, 500 microM with melatonin, and 1 mM with gamma-tocopherol. The antioxidant effect also reached a plateau at concentrations of 50 microM of E2 and 1 mM of alpha-tocopherol; gamma-tocopherol and melatonin did not reach a plateau at any dose tested. CONCLUSIONS: The antioxidant potency of E2 in vitro is at least 10-100 times greater than alpha- and gamma-tocopherol and melatonin. Whether this finding implies a better performance of E2 as a protective agent against oxidation-related diseases remains to be determined.
Chile is located in the southwestern border of South America. The country is 4,329 km long and 96-342 wide. From north to south it is divided into five marked different biogeographical zones: deserts, steppes, bushes, forests (cattle raising) and austral (sheep raising). Population (June 1999) 15,017,760 (14.6% rural). Human hydatidosis is endemic in Chile. According to Ministry of Health information about 320 cases are registered each year. In order to find out the likely prevalence of human hydatidosis in Chile, a series of serosurveys was carried out in 1988-1997 throughout the total country. By using the indirect hemagglutination reaction and ELISA for hydatidosis (tests with good sensibility and specificity) 60,790 unselected apparently healthy persons: 41,399 from urban areas (16,428 blood donors, 13,894 delivering mothers and 11,077 middle grade schoolchildren) and 19,361 from rural areas--from randomly selected family groupings--were studied. A total individuals 82 (136/100,000) resulted positive: 36 (87/100,000) urban and 46 (241/100,000) rural, being the prevalence higher in rural areas, particularly in the southern austral zone (mean 1068/100,00). These figures agree with those observed in clinical epidemiological studies. In conformity with the present results, in the whole country 17,002 individuals should have hydatidosis: 10,318 urban and 6,784 rural. All these possible infected people, not necessarily should present pathology in the future, as it has been observed in autopsies from unselected individuals, performed at the Medico-Legal Service in Santiago, in whom 71.3% of diagnosed hydatosis with hydatid cysts in many different locations, was an autopsy finding.
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Evaluation of desinsectation programs carried out in the two Health Services from the V Region, was undertaken by comparing serologic prevalences of T. cruzi infection age groups exposed to the risk of infection in rural areas during the antivectorial campaign activities (1982 vs 1995). Thus, were studied 2,193 blood samples from children under 10 years of age, proceeding from six chagasic endemic provinces in which antitriatomic domiciliary insecticide sprayings had been performed. Indirect hemagglutination and ELISA tests were carried out to each of the blood samples. A total de 42 (1.9%) children resulted positive. As in five counties no positive cases were detected in the last five years it is possible to assume that vector transmission of T. cruzi should have been interrupted in them. When comparing prevalences existing in 1982 with the present ones, it is possible to observe a 63.5% of reduction of transmission in the V Region, been this reduction higher in the Aconcagua Health Service with 79.6% and lower in the Viña del Mar--Quillota Health Service with 55.6%. According to these results, comparison of prevalence of T. cruzi infection in children less than 10-year-old in diverse periods, allows evaluate the vectorial control of Triatoma infestans programs.
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Chagas' disease, produced by Trypanosoma cruzi and transmitted by hematophagous triatomine bugs, exists in the Western Hemisphere from the south-western United States to central Chile and Argentina. It exists in rural and periurban sections of the northern half of Chile, with a prevalence of 16.9%. Constant rural-urban migrations have contributed to its spreading to urban sections. In order to investigate the impact of these migrations on the population susceptible of being blood donors and the probable increasing of the risk of T. cruzi transmission by blood transfusion, epidemiological surveys were carried out in donors from 22 hospitals located in the northern half of Chile. By means of an indirect hemagglutination test for Chagas' disease 16,841 blood donors were examined, arising a 2.7% of positivity, percentage that permitted to estimate that 126,477 potential blood donors infected with T. cruzi should be in the urban sections studied. These facts strengthen the need that serology for Chagas' disease must be routinely performed in endemic regions of the country, to adopt or reinforce the pertinent preventive measures.
Lambda-cyhalothrin (LCT) is a new broad-spectrum synthetic pyrethroid insecticide with efficient immediate and persistent activity against a great variety of arthropods harmful both to human and animal health and to vegetal production. In many countries this insecticide has been successfully used in the control of infectious diseases vectors, such as mosquitoes, triatomine bugs (transmitters of Trypanosoma cruzi, agent of Chagas' disease) and other arthropods. In order to test the immediate and persistent activity of LCT under laboratory conditions (27 degrees C and 75-80% humidity) on laboratory reared Triatoma infestans--the most resistant instar of this insect to the commonest insecticides used--a series of six experiments was performed in 1-year period. Previous to experiments, the interior surface (400 cm2) of 36 specially manufactured cardboard boxes was uniformly sprayed with 2 ml of the following substrates: 12 with 0.6% LCT suspension, 12 with 1.0% LCT suspension and 12 with water (controls). Twenty four hours, 30 - 90 - 150 - 270 and 360 days later, in two pairs of each six boxes, lots of 10 T. infestans IV nymphs were deposited inside of them. In each of the six experiments, daily observations of the conditions of the insects (unaffected, affected in terms of various grades of progressive uncoordination, or dead) after exposure to the insecticide were performed to end with the register of these conditions 96 hours later. Moreover, after 7 and 10 days of exposure in the immediate and persistent effect of LCT respectively a 100% of mortality was verified.(ABSTRACT TRUNCATED AT 250 WORDS)
An ELISA-IgG test using a soluble extract of Trypanosoma cruzi antigen has been developed. One hundred and seventy eight sera (74 healthy people, 44 chagasic patients with positive xenodiagnosis and 60 with clinical symptoms), and 64 paper filter blood eluates (35 healthy people, 10 chagasic patients and 19 with clinical symptoms) were tested by ELISA-IgG and an indirect hemagglutination test. Both types of methods presented an overall average concordance of 98.3% and 100.0% with sera and filter paper blood eluates respectively. A cut off (average of optical density plus 3 standard deviations) of 0.365 and 0.379 for sera and eluates was found. The use of ELISA-IgG in Chagas' disease clinical diagnosis and seroepidemiological studies is discussed.
To each of 11,161 randomly taken people from urban and peri-urban localities of the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country), with negative serology for Chagas' disease, an indirect hemagglutination test (IHAT) for toxoplasmosis and an EKG were practiced. The IHAT for toxoplasmosis resulted positive in 3,519 individuals (31.5%). The EKG showed alterations in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. This difference between the proportion of altered EKG in IHAT positive people and altered EKG in those with negative IHAT is statistically significative with p < 0.001. These results suggest the convenience of considering toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, since not discard the presence of Toxoplasma gondii infection should overvaluete the magnitude of the impact of Trypanosoma cruzi in the genesis of such a myocardiopathy.
In August-December 1992, 500 diaphragm muscle samples taken at random from people who were autopsied at the Santiago Medico-Legal Service, were submitted to phototrichinoscopy to search for encysted larvae of Trichinella spiralis. For each sample seven small pieces were examined. Three hundred and eighty nine (77.8%) cadavers corresponded to males and one hundred and eleven (22.2%) to females. Ages ranged from 1 to 90 years. Ten (2.0%) of the individuals examined resulted positive, the higher frequencies corresponding to individuals over 20 years of age. The prevalence rate of T. spiralis infection found is rather similar to those detected in 1966-1967, 1972 and 1982, with percentages of 2.2, 3.4 and 2.8 respectively.