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R Pardo

Publications and source records attributed to R Pardo.

At least 37 records · Page 2Linked to original sources

Formaldehyde derived from dietary aspartame binds to tissue components in vivo.

Adult male rats were given an oral dose of 10 mg/kg aspartame 14C-labelled in the methanol carbon. At timed intervals of up to 6 hours, the radioactivity in plasma and several organs was investigated. Most of the radioactivity found (>98% in plasma, >75% in liver) was bound to protein. Label present in liver, plasma and kidney was in the range of 1-2% of total radioactivity administered per g or mL, changing little with time. Other organs (brown and white adipose tissues, muscle, brain, cornea and retina) contained levels of label in the range of 1/12 to 1/10th of that of liver. In all, the rat retained, 6 hours after administration about 5% of the label, half of it in the liver. The specific radioactivity of tissue protein, RNA and DNA was quite uniform. The protein label was concentrated in amino acids, different from methionine, and largely coincident with the result of protein exposure to labelled formaldehyde. DNA radioactivity was essentially in a single different adduct base, different from the normal bases present in DNA. The nature of the tissue label accumulated was, thus, a direct consequence of formaldehyde binding to tissue structures. The administration of labelled aspartame to a group of cirrhotic rats resulted in comparable label retention by tissue components, which suggests that liver function (or its defect) has little effect on formaldehyde formation from aspartame and binding to biological components. The chronic treatment of a series of rats with 200 mg/kg of non-labelled aspartame during 10 days resulted in the accumulation of even more label when given the radioactive bolus, suggesting that the amount of formaldehyde adducts coming from aspartame in tissue proteins and nucleic acids may be cumulative. It is concluded that aspartame consumption may constitute a hazard because of its contribution to the formation of formaldehyde adducts.

Administration, Oral↗

Determination of copper and arsenic in refined beet sugar by stripping voltammetry without sample pretreatment.

Copper and arsenic have been analysed in refined beet sugar at the microgram kg-1 level by anodic stripping voltammetry (copper) and cathodic stripping voltammetry (arsenic) in the differential-pulse mode (DPASV and DPCSV) at a hanging mercury drop electrode (HMDE). DPCSV measurements of arsenic are based on its accumulation onto the HMDE as an intermetallic Cu-As compound followed by the reduction of As0 to arsine in hydrochloric acid medium. Measurements were directly carried out on untreated sugar solutions. The performance of the procedures was compared with electrothermal atomic absorption spectrometry and stripping voltammetry applied to digested sugar samples, and showed in general better accuracy. The procedures were applied to the determination of these toxic elements in commercial beet sugar samples of concentrations below 50 micrograms kg-1 copper and 15 micrograms kg-1 arsenic were found, which are much lower that those allowed by the current regulations.

Arsenic↗

Genetic structure of local populations of Lutzomyia longipalpis (Diptera: Psychodidae) in central Colombia.

Lutzomyia longipalpis (Lutz & Neiva), the sand fly vector of American visceral leishmaniasis in the New World tropics, has a broad but discontinuous geographical distribution from southern Mexico to Argentina. A baseline for population genetic structure and genetic variability for this species was obtained by analyzing 5 local, peridomestic populations at the approximate center of its distribution, the Magdalena River Valley of central Colombia. Three populations of L. longipalpis from El Callejón, a small rural community, were compared with 2 populations from neighboring areas 12 and 25 km distant for genetic variation at 15 isoenzyme loci. The mean heterozygosity ranged from 11 to 16%, with 1.2 to 2.3 alleles detected per locus. Nei's genetic distances among the populations were very low, ranging from 0.001 to 0.007. Gene flow estimates based on FST indicated high levels of gene flow among local L. longipalpis populations, with minimal population substructuring.

Alleles↗

Larval microhabitats of Lutzomyia longipalpis (Diptera: Psychodidae) in an endemic focus of visceral leishmaniasis in Colombia.

An intensive search for the larval habitats of Lutzomyia longipalpis (Lutz & Neiva) was conducted from November 1992 to October 1993 at a small rural community in Colombia where American visceral leishmaniasis is endemic. Emergence traps constructed from polyvinyl chloride pipes were used to sample a variety of soil microhabitats that included edge areas of covered pigpens, cattle corrals, the base of trees, and leaf litter at sites within 40 m of a house, rocks in fields located between 50 and 500 m from houses, and sites within a patch of secondary forest (rocks, base of palm trees, and leaf litter). The teneral status of the sand flies captured in the emergence traps was confirmed by laboratory studies that determined the rate of terminalia rotation in male L. longipalpis and the rate of cuticular growth layer formation of the thoracic phragma in both sexes of this species. A total of 58 teneral sand flies was captured during the study period (49 wk). Fifteen specimens were L. longipalpis; of these 11 (5 sand flies per square meter) were captured near pigpens, 3 (1.4 sand flies per square meter) were captured near rock resting sites, and 1 (1.6 sand flies per square meter) was collected at the base of a tree. The remainder of the sand flies were either L. trinidadensis (Newstead) or L. cayennensis (Flock & Abonnenc). Our results indicate that L. longipalpis larvae were dispersed widely in sites near houses, rather than concentrated in a few optimal microhabitats.

Animals↗

The treatment of scabies with ivermectin.

BACKGROUND: Ivermectin is an anthelmintic agent that has been a safe, effective treatment for onchocerciasis (river blindness) when given in a single oral dose of 150 to 200 micrograms per kilogram of body weight. Anecdotal reports of improvement in patients who suffered from infestation with the mite Sarcoptes scabiei suggest that the ectoparasitic disease scabies might be treated with ivermectin. METHODS: We conducted an open-label study in which ivermectin was administered in a single oral dose of 200 micrograms per kilogram to 11 otherwise healthy patients with scabies and to 11 patients with scabies who were also infected with the human immunodeficiency virus (HIV), 7 of whom had the acquired immunodeficiency syndrome. All patients received a full physical and dermatologic examination; scrapings from the skin of all patients tested positive for scabies. Patients were reexamined two and four weeks after treatment, when the scrapings for scabies were repeated. The patients used no other scabicides during the 30 days before ivermectin treatment or during the 4-week study period. RESULTS: None of the 11 otherwise healthy patients had evidence of scabies four weeks after a single dose of ivermectin. Of the 11 HIV-infected patients, 2 had < or = 10 scabies lesions before treatment, 3 had 11 to 49 lesions, 4 had > or = 50 lesions, and 2 had heavily crusted skin lesions. In eight of the patients the scabies was cured after a single dose of ivermectin. Two patients received a second dose two weeks after the first. Ten of the 11 patients with HIV infection (91 percent) had no evidence of scabies four weeks after their first treatment with ivermectin. CONCLUSIONS: The anthelmintic agent ivermectin, given in a single oral dose, is an effective treatment for scabies in otherwise healthy patients and in many patients with HIV infection.

Acquired Immunodeficiency Syndrome↗

Species composition and relative abundance of sand flies of the genus Lutzomyia (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1993 at a small rural community in Colombia where American visceral leishmaniasis is endemic. Weekly sand fly collections were made from pigpens, houses, and natural resting sites, using hand-held aspirators, sticky (oiled) paper traps, and opossum-baited Disney traps. In total, 263,094 sand flies were collected; L. longipalpis predominated (86.1%), followed by L. trinidadensis (11.0%), L. cayennensis (2.7%), and 8 other Lutzomyia species. The species composition and sex ratio of these sand flies varied among sites and by collection method. L. longipalpis were captured most efficiently by direct aspiration from animal bait. Conversely, sticky paper traps, especially inside houses and at rock resting sites, collected a greater diversity of species, but a lower relative abundance of L. longipalpis.

Animals↗

Seasonal abundance of Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1993 in a small rural community in Colombia where American visceral leishmaniasis is endemic. Standardized weekly sand fly collections made from pigpens and natural resting sites displayed a bimodal annual abundance cycle, with a small peak occurring in October-November and a larger one in April-May. Time series analysis was employed to quantify the associations between sand fly abundance and weather factors (temperature, relative humidity, and rainfall). In addition to a prominent 6-mo cycle. Fourier analysis of the collection data demonstrated that the L. longipalpis population also exhibited a 5- to 8-wk cycle that may represent the length of larval development. Autoregressive moving average models were fit to weekly collection data and their residuals were regressed against rainfall, temperature, and relative humidity. A significant positive association between female L. longipalpis abundance and the relative humidity and rainfall recorded 3 wk earlier was found, indicating that these factors may be of value in predicting sand fly abundance. Additionally, these data indicated that L. longipalpis larvae may become quiescent during adverse conditions.

Animals↗

Nocturnal activity patterns of Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Nocturnal activity of the sand fly Lutzomyia longipalpis (Lutz & Neiva) was studied from August 1991 to July 1992 in a small rural community in Colombia where American visceral leishmaniasis is endemic. During 2 or 3 nights each month, sand flies were collected with hand-held aspirators each hour between 1730 and 0630 hours, from a pigpen and a cattle corral located 30 m apart. Host-seeking activity of L. longipalpis adults was characterized by 2 general patterns: (1) adult sand fly activity increased shortly after sunset and continued until just after sunrise, and (2) peak sand fly activity was greatest early in the evening (1830-2330 hours) and then declined steadily toward morning. Female L. longipalpis activity generally increased after 2030 hours, whereas that of males remained constant or declined as the evening progressed. There were seasonal differences in sand fly abundance between the 2 sites: peak abundance in the cattle corral occurred during hot, dry periods, whereas maximum abundance in the pigpen occurred when relative humidity was higher. Influence of relative humidity on activity varied with season. Sand fly activity tended to decrease at temperatures below 24 degrees C and increase in the presence of moonlight.

Animals↗

Age structure, blood-feeding behavior, and Leishmania chagasi infection in Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1992 in a small rural community in Colombia where American visceral leishmaniasis (AVL) is endemic. Subsamples of sand flies collected weekly from pigpens, the interior of houses, and natural outdoor resting sites were dissected to determine physiological age and Leishmania chagasi Cunha & Chagas infection rates. Eleven female L. longipalpis had flagellates in their gut, 2 of which were successfully cultured and identified as Leishmania chagasi. The reproductive status, stage of ovarian development, and trophic history of female sand flies varied among sites, habitats, and time of collection. The percentage of parous females ranged from about one-third to two-thirds overall and varied seasonally. Of most relevance to AVL transmission was the finding that 8% of L. longipalpis females were multiparous. In addition, our data suggest that L. longipalpis rest inside houses after blood-feeding outdoors, and that this species can blood-feed more than once during a single gonotrophic cycle.

Aging↗

Endoscopic retrograde cholangiopancreatography: before and after laparoscopic cholecystectomy.

In 39 patients with indication of laparoscopic cholecystectomy (LC), an endoscopic cholangiopancreatography (ERCP) was performed before the procedure whenever intermittent cholestasis, acute pancreatitis or ultrasonografic biliary tract dilatation were detected. No abnormality was found in 24 of them. In 14, bile duct stones were removed by endoscopic sphincterotomy (EST). Later they were submitted to LC, and no complication was observed. Only 1 patient with cholangiografic diagnosis of Mirizzi's syndrome underwent open cholecystectomy. Twenty-four patients were referred to ERCP between 2 and 210 days following LC, after development of complications. The etiology of these complications could be established in all the cases. Sixteen patients had bile duct stones, 14 of them were treated successfully by EST and 2, with multiple stones, required open surgery extraction. Four patients had cystic bile leaks, of which 1 healed spontaneously, 1 closed his fistula after EST and removal of stones, 1 cured after a nasobiliary tube was inserted endoscopically and 1 required surgical treatment. Four patients with complete obstruction of common bile duct by misplaced clips received surgical treatment. We conclude that ERCP is indicated before LC in patients with clinical, humoral or ultrasound findings of extrahepatic cholestasis. The application of EST plus LC systematically in cases of biliary duct stones remains still controversial. We agree that ERCP is an excellent method in the diagnosis and treatment of LC complications.

Adult↗

[Misoprostol and cimetidine in the treatment of active duodenal ulcer. Multicenter, double-blind, clinico-endoscopic study. The Argentine experience].

Ten Argentine centers participated in this cooperative trial. One hundred and sixteen patients with endoscopically proven duodenal ulcer entered the study and were randomly assigned to receive either Misoprostol 800 micrograms or Cimetidine 1200 mg, q.i.d. per day, during four weeks of treatment. Patients were allowed to take Amphogel tablets for relief of ulcer pain when necessary, and clinical, lab-tests and adverse effects were evaluated weekly. Ninety-nine patients (Misoprostol 54, Cimetidine 45) completed the study and were evaluable. Success/failure criteria were based on endoscopically documented complete healing at the end of treatment period. Healing rate of four week was 85.2 per cent (46/54) for Misoprostol and 75.5 per cent (34/45) for Cimetidine, with no statistically significant difference. It is concluded that Misoprostol and Cimetidine are highly effective and safety in the healing of active duodenal ulcer. Misoprostol is a new therapeutical alternative for the treatment of duodenal ulcer patients.

Adolescent↗

Segmental myoclonus. Clinical and pharmacologic study.

We observed 37 patients (mean age at onset, 48.5 years; range, 13 to 84 years) with segmental myoclonus (18 branchial, 19 spinal). Etiologies for branchial myoclonus included brain-stem demyelination, cerebrovascular disease, Meige's syndrome, cerebral arteritis secondary to bacterial meningitis, central nervous system Whipple's disease, acute cervicomedullary trauma, and cerebellar degeneration. Spinal myoclonus was associated with laminectomy, remote effect of cancer, spinal cord injury, post-operative pseudomeningocele, laparotomy, thoracic sympathectomy, poliomyelitis, herpes myelitis, lumbosacral radiculopathy, spinal extradural block, and myelopathy due to demyelination, electrical injury, acquired immunodeficiency syndrome, and cervical spondylosis. The latency between the predisposing condition and the onset of myoclonus ranged from immediate to 33 years (mean, 2.9 years). In six patients, the myoclonus was the presenting symptom of a serious underlying disease. Treatment with clonazepam, tetrabenazine hydrochloride, or other medications provides a satisfactory control in most patients.

Adolescent↗

Immunocytochemical localization of relaxin in endometrial glands of the pregnant guinea pig.

Relaxin was localized in the cytoplasm of endometrial gland cells in the uterus of day 60 pregnant guinea pigs with the peroxidase-antiperoxidase method. The immunoprecipitate was located over the apical portions of the glandular cells. Stain was not found over non-endometrial portions of the uterus, endometrial surface epithelium or cells of the uterine cervical glands. Agar double-immunodiffusion analyses demonstrated a reaction of identity when extracts of uterus from day 60 pregnant guinea pigs and a porcine relaxin standard were tested with an antiserum produced against highly purified porcine relaxin. An extract of uteri from day 60 pregnant guinea pigs gave a positive response in the mouse uterus bioassay for relaxin.

Animals↗