PubMed Health⌕ Search

Biomedical subjects

L Castillo

Publications and source records attributed to L Castillo.

At least 109 records · Page 6Linked to original sources
PubMed1993

Splanchnic metabolism of dietary arginine in relation to nitric oxide synthesis in normal adult man.

Urinary nitrate (NO3) is the stable end product of nitric oxide, which is formed, in turn, from a guanidino nitrogen of arginine. We have conducted two experiments, each in four healthy adult men receiving a low nitrate diet for 7-10 days, to investigate the in vivo conversion of arginine to nitrate. In the first study [guanidino-15N2, 5,5-2H2]arginine was given on day 7 via a primed continuous intravenous infusion for 8 h. In the second study, the labeled arginine was given for 8 h by the intragastric route on day 7 and by the intravenous route on day 10. Measurement of 15NO3 output in urine collected for 24 h beginning at the time of the arginine tracer infusion revealed a more extensive transfer of 15N when the arginine tracer was given intragastricly. From the comparative labeling of 15NO3 after administration of the tracer arginine via the intragastric and intravenous routes, we estimate that 16% +/- 2% of the daily production of nitrate arises from the metabolism of dietary arginine that is taken up during its "first pass" in the splanchnic region. Hence, nitric oxide production occurs, to a measurable extent, in this area in healthy subjects, raising the question as to how various pathophysiological states might alter the relations between exogenous and endogenous sources of arginine as precursors of NO. and the relative contributions made by various organs to whole body (NO.) NO3 formation. These results also raise important questions about the use of nitric oxide synthase inhibitors in animal and human studies.

Adult↗
PubMed1993

Experimental transmission of murine malaria by the oral route.

A total of 116 young male CD1 mice were orally inoculated with mouse blood; half of the animals received 0.2 ml of uninfected blood and the others were given 0.2 ml of Plasmodium berghei yoelii-infected blood in six experiments performed at different times. Almost 30% of the experimental mice acquired malaria as demonstrated by the observation of parasites in their blood. In no case were parasites found in the blood of control mice. Rodent malaria parasites may be transmitted to CD1 mice by the ingestion of mouse blood parasitized by P. b. yoelii. As far as we know, this study represents the first demonstration of oral transmission of murine malaria. Oral transmission studies in this mouse-Plasmodium model may produce very important information on the biology of the malaria parasites.

Administration, Oral↗
PubMed1993

Phenylalanine conversion to tyrosine: comparative determination with L-[ring-2H5]phenylalanine and L-[1-13C]phenylalanine as tracers in man.

The in vivo rate of conversion of phenylalanine to tyrosine (PheOH) can be estimated using combinations of stable isotope-labeled phenylalanine and tyrosine. We have compared in four healthy adult men the rates of phenylalanine conversion to tyrosine based on the following pairs of primed, continuous tracer infusions administered simultaneously: (1) L-[ring-2H5]phenylalanine and 2H2-tyrosine with a 2H4-tyrosine prime, and (2) L-[1-13C]phenylalanine and 2H2-tyrosine with a 1-13C-tyrosine prime. Phenylalanine oxidation was determined from measurement of 13CO2 excretion in expired air. Tracers were given for 8 hours, with subjects being in the postabsorptive state during the first 3 hours and in the fed state during the remaining 5 hours. Mean (+/- SD) rates (mumol.kg-1.h-1) of phenylalanine conversion to tyrosine for fasted and fed states, respectively, were 5.1 +/- 2.9 and 6.8 +/- 3.4 with 2H5-phenylalanine and significantly higher (P < .05) at 11.1 +/- 5.6 and 12.7 +/- 7.7 with 13C-phenylalanine as tracer. Phenylalanine oxidation was 9.9 +/- 2.0 and 13.5 +/- 2.6, respectively, for fasted and fed states, and these mean values did not differ (P > .1) from the rate of phenylalanine conversion to tyrosine determined using 13C-phenylalanine. These results indicate the need for caution in interpreting kinetic aspects of phenylalanine metabolism when based on isotopic data from multideuterated phenylalanine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Lack of effect of octreotide on parathyroid hormone levels and urinary excretion of epidermal growth factor.

To determine whether octreotide may acutely modify calcium homeostasis and/or inhibit the EGF production by the kidney, a subcutaneous injection of octreotide (100 micrograms) was administered to ten healthy volunteers. Blood and urine samples were collected at -30, 0, 60, 90, 120 and 180 minutes. Serum insulin, intact PTH, osteocalcin, total and ionized calcium and urinary EGF and creatinine were measured. There was no modification in serum PTH, osteocalcin and total or ionized calcium. There was no significant modification of urinary EGF, although a trend to decrease was evidenced.

Adult↗
PubMed1993

Dietary arginine uptake by the splanchnic region in adult humans.

To determine the uptake of dietary arginine and leucine by the splanchnic region, two experiments were carried out, each involving four healthy young adult men who received a diet supplying 1 g protein.kg-1.day-1 for 7 and 10 days before conducting a primed constant tracer infusion protocol. In study 1, subjects received for 8 h (3-h fast; 5-h fed state, achieved by a constant intragastric infusion of the diet formula) L-[5,5-2H2; guanidino-15N2]arginine ([M4]Arg), L-[guanidino-13C]arginine ([13C]Arg), and L-[5,5,5-2H3]leucine ([2H3]Leu) simultaneously by an intragastric infusion on day 7 and a repeat of this protocol on day 10 except with tracer administration given by vein. Plasma arginine fluxes were essentially the same for the two arginine tracers but differed significantly with route of administration. In study 2 the subjects received on day 7 a constant intravenous infusion of [13C]Arg and [2H3]Leu and a simultaneous intragastric infusion of [M4]Arg and [1-13C]leucine. On day 10 the routes of administration of these tracer pairs were reversed. During the fed state in study 1, splanchnic uptake of dietary arginine was 31 +/- 10 and 34 +/- 8%, based on the [13C]Arg and [M4]Arg tracers, respectively, and it was significantly higher (P < 0.01) than for leucine, which was 10 +/- 6%. In study 2, splanchnic uptake of dietary arginine, estimated from a series of tracer-protocol combinations for the fed state, was approximately 38% compared with a lower (P < 0.01) value of approximately 15% for leucine.

Adult↗
PubMed1993

Transcriptional and posttranscriptional control in synthesis of growth marker polypeptides in mouse parotids.

The chronic daily administration of isoproterenol provokes in mouse parotid glands the induction and progressive accumulation of a family of secretory polypeptides named polypeptides C, D, E, F, and G (polypeptides C-G). These polypeptides, which seem to be part of the family of proline-rich proteins, have been considered as molecular markers of the growth-in-size response in the mouse parotid acinar cells. In the present study, two pharmacological approaches were used to determine whether the induction and the postsecretory reappearance of polypeptides C-G may be distinguished from each other. First, actinomycin D, a transcriptional inhibitor, was found to interfere with the induction by isoproterenol but not with the postsecretory reappearance. Second, pilocarpine, a secretagogue that was found to be a very weak inducer of polypeptides C-G, was able to provoke secretion and then reappearance of the whole group of isoproterenol-induced polypeptides. Accordingly, these data suggest that the induction of polypeptides C-G is dependent on transcriptional activity and that it is unrelated to secretion stimulation. By contrast, the postsecretory reappearance of polypeptides C-G may occur even when transcriptional activity is inhibited and it would be related to the secretory activity.

Animals↗
PubMed1993

Pesticide poisonings in Costa Rica.

A descriptive epidemiologic study, conducted in Costa Rica, investigated the incidence of pesticide poisonings with special attention to agricultural workers and occupational exposure. Information from three national registers (occupational accident and disease reports, hospitalizations, and deaths) were used. During 1986, 1800 occupational accidents caused by pesticides were reported; between 1980 and 1986 altogether 3330 persons were hospitalized and 429 died. Cholinesterase inhibitors caused 71% of the reported occupational accidents, 63% of the hospitalizations, and 36% of the deaths. Paraquat caused 21% of the occupational accidents, 24% of the hospitalizations, and 60% of the deaths. Hospitalizations and deaths were 13 and 11 times, respectively, more frequent among agricultural workers than among the rest of the population. High-risk groups for occupational poisonings included agricultural workers aged 15-29 years, female workers, and banana plantation workers. The yearly incidence of symptomatic occupational pesticide poisonings among agricultural workers was estimated at 4.5%.

Adolescent↗
PubMed1993

[Prevalence of hepatitis C virus antibodies in chronic hemodialysis and kidney transplantation patients].

Hepatitis C virus antibodies were measured in 26 chronic hemodialyzed patients and 43 kidney transplant recipients, using a second generation ELISA method. Fifty four percent of hemodialyzed had a longer duration of dialysis treatment compared with patients with negative antibodies (57.6 +/- 30.5 vs 15.4 +/- 7.3 months), and did not differ in the number of transfusions. Seven patients had elevated serum transaminase values, all with positive antibodies. Thirty five percent of kidney transplant recipients had positive antibodies. In these subjects, no relation was observed between the number of transfusions or length of dialysis treatment and the presence of positive hepatitis C antibodies.

Adult↗
PubMed1992

[Creutzfeldt-Jakob disease. The first case with histopathological study in Panama].

We studied the clinical and histopathology findings of the first proved case of Creutzfeldt-Jakob disease in Panama. A sixty-five-years-old female patient referred from Santiago de Veraguas was admitted to Santo Tomás Hospital with a progressive clinical picture of dementia, incoordination and generalized myoclonia. The electroencephalogram showed periodic paroxysmal activity. The patient died eight months after initiated the disease. The cerebral histopathologic study was characteristic of Creutzfeldt-Jakob disease: status spongiform, neuronal loss and non-inflammatory gliosis was found.

Aged↗
PubMed1990

Human T-cell lymphotropic virus type I and neurologic disease in Panama, 1985 and 1986.

Human T-cell lymphotropic virus type I (HTLV-I) causes adult T-cell leukemia and has recently been associated with HTLV-associated myelopathy/tropical spastic paraparesis. The HTLV-I is endemic throughout the Caribbean basin and parts of South America, and HTLV-associated myelopathy/tropical spastic paraparesis also seems to be common in this area. This 2-year study, 1985 and 1986, was designed to evaluate the occurrence of HTLV-I infection in all newly diagnosed cases of selected neurologic diseases in Panama City, Panama. Six (8%) of 71 patients had antibody to HTLV-I detected by immunofluorescence, enzyme-linked immunosorbent assay, radioimmunoassay, and Western blot assays; 5 patients' conditions were diagnosed as spastic paraparesis, and all 5 were seropositive and also had HTLV-I antibody in cerebrospinal fluid. The remaining seropositive patient had multiple sclerosis, and no antibody was detected in her cerebrospinal fluid. Clinical and electrophysiologic studies indicated that HTLV-I-associated spastic paraparesis is a multifocal, primarily demyelinating disease that principally involves the spinal cord.

Adult↗
PubMed1990

Isolation of human T-cell lymphotropic virus type 2 from Guaymi Indians in Panama.

Human T-lymphotropic virus type I (HTLV-I) is associated with adult T-cell leukemia/lymphoma and with a chronic degenerative myelopathy. However, another major type of HTLV, HTLV-II, has been isolated only sporadically, and little is known of disease associations, transmission routes, and risk factors for HTLV-II infection. Recent studies indicate that a high percentage of certain groups of i.v. drug users and blood donors are infected with HTLV-II. Seroepidemiologic studies have found an elevated rate of seroreactivity to HTLV among Guaymi Indians from Bocas del Toro Province, Panama. To identify the cause of seroreactivity among this unique population we used HTLV-II-specific polymerase chain reaction techniques to detect HTLV genetic sequences from blood leukocytes of three seropositive Guaymi Indians. The HTLV-II primer-amplified polymerase chain reaction products from two of these subjects were partially sequenced and matched published HTLV-II nucleotide sequences in both p24 gag (94% of 107 bases) and pol (98% of 112 bases) regions. A CD4+ T-lymphocyte line established from one of these same subjects produced HTLV-II-specific proteins when tested in antigen-capture and immunoblot assays, as well as mature HTLV particles. The demonstration of HTLV-II infection in this geographically and culturally isolated Central American Indian population without typical risk factors for HTLV infection suggests that HTLV-II infection is endemic in this population and provides an important clue to potential natural reservoir for this virus.

Base Sequence↗
PubMed1990

Neurocysticercosis in Panama: preliminary epidemiologic study in the Azuero region.

Neurocysticercosis was not been reported from Panama until 1984. The first documented case was a 5-year-old male who lived with his family in a typical subsistence agriculture environment lacking all sanitary amenities. Pigs and other animals ranged freely in and around the home. This report concerns clinical studies of the patient and his family conducted 4 years later. The index case had neurologic sequelae and was strongly seropositive. A cerebral CT scan revealed multiple intracerebral calcifications. Three family members had antibody to Cysticercus detected by immunoblot assay. A 7-year-old seropositive sister had an intracerebral calcification detected by CT scan. All 6 family members had completely normal neurologic examinations.

Adolescent↗
PubMed1990

Human T cell lymphotropic virus infection in Guaymi Indians from Panama.

Preliminary studies found that 9% of Guaymi Indians from Bocas del Toro province have antibody to human T cell lymphotropic virus (HTLV-I/II). The present study enrolled 317 (21% of the population) Guaymi Indians from Changuinola, the capital of Bocas del Toro province and 333 (70% of the population) from Canquintu, an isolated rural village. Demographic information and family relationships were ascertained and subjects were screened for neurologic diseases. Serum specimens were screened by an enzyme-linked immunosorbent assay for HTLV-I/II antibody and positives were confirmed according to U.S. Public Health Service criteria. Twenty-five (8%) Guaymi residing in Changuinola and 7 (2.1%) from Canquintu were confirmed seropositive. In Changuinola, antibody was virtually limited to residents greater than or equal to 15 years of age (24 [16%] of 153) and rates were slightly higher in males than in females; in Canquintu, antibody rates did not increase significantly with age and appeared higher in females than in males. In Changuinola, there was no evidence for household clustering of infection. In contrast, HTLV antibody among Canquintu residents clustered significantly by household. HTLV-associated neurologic disease was not detected in either population. The atypical seroepidemiology observed in both locations might be explained if the virus endemic to the Guaymi differed from HTLV-I previously described in the Caribbean basin and Japan.

Adolescent↗
PubMed1990

[Fractures of the mandible. A critical study of repair procedures].

Based on their personal experience of 110 patients operated on for mandibular trauma, the authors analyse the results of the various techniques used. Screwed micro-plates may be very useful but only complete the therapeutic arsenal of the surgeon. In fact classical methods continue to provide satisfactory results. Poorer results may occur with fractures which combine involvement of the articular surfaces with a lesion of the body of the mandible.

Adolescent↗