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Biomedical subjects

P Calderon

Publications and source records attributed to P Calderon.

At least 19 recordsLinked to original sources
PubMed2003

Survey of the growth characteristics and body composition of Fulani children in a rural hamlet in northern Nigeria.

This paper reports the results of a cross-sectional study of the growth of Fulani children, aged 1-16 years, living in the Jos Plateau of northern Nigeria. This particular population of Fulani are semi-nomadic pastoralists whose economy and culture are centered on cattle. We measured the heights and weights of 176 girls and 164 boys and determined their body composition parameters (fat content, fat-free mass, and phase angle) using bioelectrical impedance analysis. The body mass index values for the boys and girls were 14.9 and 15.0 kg/m2, respectively. When the heights and weights of the Fulani children were compared against World Health Organization standards, the incidence of stunting and underweight was high: 46 per cent of the girls and 57 per cent of the boys, respectively, had weight Z-scores below -1.0, and 42 per cent and 57 per cent had height Z-scores below -1.0. Even when weight was adjusted for height, the boys and girls fell well below their age- and gender-matched standards. The percentage fat content of the children declined with age such that by age 16 years the fat content of the boys was 10 per cent and that of the girls 20 per cent. Although the Fulani children were significantly shorter and lighter than the international standards, their phase angle value (determined by bioelectrical impedance analysis), which is a measure of body cell mass and the overall vitality and health of tissue membranes, was comparable to those of similarly aged healthy children in the United States. These results indicate that although a large proportion of the Fulani children who inhabit the Jos Plateau are stunted and underweight, the bioelectrical properties of their tissue membranes suggest that they are relatively healthy. It is not known if the slow growth of the Fulani children has a genetic basis or if it is the result of nutritional shortcomings.

Adolescent↗
PubMed1997

Comparison of bronchodilating effects of two salbutamol dry powder inhalers in asthmatic patients.

In an open, randomized crossover study two different types of dry powder inhalers (DPIs) were compared. Twenty-five adult asthmatic patients inhaled a single dose of 200 micrograms of salbutamol (CAS 18559-94-9) on two separate days. Salbutamol was administered either from a novel multidose DPI (Easyhaler, test DPI) or from another type of DPI (reference DPI). On both study days lung function, blood pressure and heart rate were measured during a 4-h follow-up period. Both powder inhalers caused a clear increase in lung function parameters. The mean (SD) maximum forced expiratory volume in 1 s (FEV1) after the test DPI was 3.25 (1.30) 1 and after the reference DPI 3.28 (1.29) 1. The mean relative change from the baseline in FEV1 was similar after administration of both preparations. The mean area under the curve (AUC0-4h) of the absolute FEV1 values was 729 (316) and 731 (309) 1 x min after test and reference DPIs, respectively. The salbutamol doses had no clinically significant effects on blood pressure or heart rate and were equally well tolerated. Furthermore, 41% of patients preferred the test DPI and 19% the reference DPI, while 40% felt there was no difference between the devices. In conclusion, the results of this study show that the test DPI, a novel multidose powder inhaler, is an effective, safe and convenient alternative when an inhaled bronchodilator treatment is considered for an obstructive patient.

Administration, Inhalation↗
PubMed1996

Pharmacokinetics of nitazoxanide after single oral dose administration in 6 healthy volunteers.

The objective of this study was to gather first information on the time course of plasma concentrations and urinary excretion of the antiprotozoal nitazoxanide (N) and to identify potential metabolites in healthy subjects after a single oral dose of 500 mg of nitazoxanide. The clinical trial was conducted as an open single oral dose study in 6 healthy male subjects. After a standardized continental breakfast the subjects took a single oral dose of 500 mg nitazoxanide (coated tablet) with 100 ml tap water. The plasma concentration and the urinary excretion of nitazoxanide (N), desacetyl-nitazoxanide (DN), aminonitrothiazole (ANT), acetylsalicylate (AS), salicylate (S), gentisate (G) and salicylurate (SU) were monitored up to 72 h after administration. The only measurable species in plasma was DN, which reached a Cmax of 1.9 mg/l (range 1.1-2.5) 2-6 h after dosing, and an AUC of 3.9-11.3 mg x h/l. Its terminal half-life ranged from 1.03 to 1.6 h. DN was extensively bound to plasma proteins (> 97.5%). Only 8% of the dose was recovered in the urine, in the form of DN (5%), SU (3%), and traces of ANT (0.1%). In vitro N was very rapidly hydrolyzed to DN by plasma esterases.

Administration, Oral↗
PubMed1994

Exploratory study of the decongestive effect of Rhinopront syrup in adults and in children with acute rhinitis.

The decongestive effect of Rhinopront syrup was assessed in 18 adults and 18 children with acute rhinitis, by comparison to a matching placebo syrup and to a commercial standard decongestant (Triaminic tablets or drops). The evolution of symptoms following single dose administration of each treatment was estimated both by objective measurements of nasal resistance using bilateral rhinomanometry and by subjective evaluation of nasal congestion and aspect of the mucosa. In children, the treatment was continued over the next 4 days and the global clinical efficacy of the formulations was subjectively evaluated by the parents. In adult patients, a significant decrease in nasal resistance was obtained after a single dose of Rhinopront (15 g). The effect was already important after 0.5 h and reached a minimum of approximately 50% of baseline within 1 to 2 h; the drop in nasal resistance was significantly less intense for Triaminic (p < 0.05; 0.5-1-h period) and for the placebo (p < 0.05; 0.5-2-h period). In children, the scatter of rhinomanometric measurements precluded the observation of any significant within- or between-group differences; however, a significantly lower nasal congestion score was observed for Rhinopront than placebo, between 4 and 10 h after single dose administration (1 g per year of age). The present work suggests that Rhinopront is an effective nasal decongestant in adults and children with acute congestive rhinitis and supports the adequacy of the proposed twice-daily dosing rate.

Acute Disease↗
PubMed1988

Familial multiple trichodiscomas.

A familial multiple trichodiscoma involving two sisters is reported. Trichodiscoma is a benign neoplasm of the mesenchymal component of the hair disk characterized clinically by asymptomatic papules and histologically by a dermal fibrovascular proliferation. Familial involvement and associations with other follicular neoplasia should be investigated in all cases.

Adult↗
PubMed1987

Arterial reactivity, blood pressure, and plasma levels of atrial natriuretic peptides in normotensive and hypertensive rats: effects of acute and chronic administration of atriopeptin III.

We compared acute and chronic effects of atriopeptin III in normotensive and spontaneously hypertensive rats. Atriopeptin III relaxed isolated aortae and intrarenal microarteries but not coronary and mesenteric microarteries of normotensive rats. Effects on arterial smooth muscle were comparable in hypertensive and normotensive rats and were not affected by long-term treatment of the animals with the peptide. Acute administration of atriopeptin III (4-400 nmol/kg, intravenously) reduced systolic blood pressure in conscious spontaneously hypertensive and renal hypertensive rats but not in normotensive rats. In spontaneously hypertensive rats, nephrectomy increased the sensitivity to and the duration of the acute antihypertensive effect. Renal subcellular fractions rapidly inactivated atriopeptin III in vitro. This atriopeptinase activity was comparable for normotensive and spontaneously hypertensive rats and was not affected by long-term treatment of the rats with the peptide. Continuous administration of low doses of atriopeptin III (0.4 and 4.0 nmol/kg/h, intravenously (i.v.) during 7 days) caused a progressive reduction in systolic blood pressure in spontaneously hypertensive but not in normotensive rats. It did not affect plasma levels of aldosterone or renin and resulted in less than a doubling of the plasma levels of atrial natriuretic peptides. These findings confirm that atrial natriuretic peptides preferentially relax the renal microvasculature. They demonstrate that although atriopeptin III comparably relaxes arterial smooth muscle of normotensive and spontaneously hypertensive rats, both acute and chronic administration of the peptide preferentially lower blood pressure in hypertensive rats. Rather than contributing to the effects on blood pressure, the kidneys modulate the duration of action of atrial natriuretic peptides.

Animals↗
PubMed1986

In vitro vasorelaxing activity of suloctidil.

The vasorelaxing effect of suloctidil was evaluated in isolated rat and rabbit aorta and in isolated rabbit mesenteric and saphenous artery. Suloctidil inhibited contractions induced by increasing extracellular calcium in depolarized arteries, mainly in a competitive way. In the rat aorta, the pA2 value was 7.50 for suloctidil, while pA2 values of 9.96, 7.90 and 8.10 were obtained for nifedipine, cinnarizine and verapamil, respectively. Suloctidil more potently inhibited calcium-induced contractions in small arteries (mesenteric and saphenous artery), than in the aorta. Suloctidil also reduced the tonic component of the responses to norepinephrine. In contrast to the effects on calcium-induced contractions, the effects of suloctidil on norepinephrine-induced responses was mainly noncompetitive. In addition, and unlike cinnarizine and verapamil, high concentration of suloctidil also reduced the phasic component of contractile responses to norepinephrine. Furthermore, unlike nifedipine, verapamil, diltiazem and cinnarizine, suloctidil was devoid of a negative inotropic effect in spontaneously beating guinea-pig atria. In conclusion, suloctidil behaves as a Ca2+-channel blocker in arteries and displays an additional mode of action that could include receptor-operated Ca2+-channels or an intracellular site of action. In addition, suloctidil was found to affect small arteries more than the aorta, and not to affect the atria.

Animals↗
PubMed1983

Familial focal segmental glomerulosclerosis.

We have observed the nephrotic syndrome in more than one sibling in three unrelated hispanic families. The histological lesion in the involved children was either focal segmental glomerulosclerosis or IgM nephropathy evolving into focal sclerosis. Tissue typing revealed the presence of HLA DRw8 in six out of eight patients. The frequency of this antigen in our patients, when compared with its frequency in a group of unrelated normal hispanic children was highly significant (p less than 0.0001). Our study suggests that there may be a genetic predilection towards developing focal segmental glomerulosclerosis.

Adolescent↗
PubMed1980

Phosphatidylinositol turnover and calcium movement in the rat pancreas.

Carbamylcholine, bombesin, pancreozymin, and pentagastrin elicited a similar increase in amylase secretion and phosphatidylinositol turnover in rat pancreatic fragments. The concentration of each secretagogue that provoked half-maximal stimulation of amylase secretion was three to six times lower than that which induced half-maximal stimulation of phosphatidylinositol turnover. The increased turnover of phosphatidylinositols due to carbamylcholine or pancreozymin, but not the secretory response, persisted in a calcium-free medium or in 90% heavy water. The replacement of the media Na+ with Li+ increased an atropine-resistant turnover of phosphatidylinositols, but did not stimulate secretion. The ionophore A-23187 (in a medium containing 2.5 mM Ca2+) and 10 mM NaF induced a high secretory response, but exerted no effect on phosphatidylinositol turnover. K+ at a 70 mM concentration provoked a phosphatidylinositol effect and hypersecretion. Secretin, vasoactive intestinal peptide, dibutyryl cAMP, dibutyryl cGMP, 8-bromo cGMP, and N2-monobutyryl cGMP stimulated amylase secretion without an increased turnover of phosphatidylinositols. It is concluded that, in the rat pancreas, the increased turnover of phosphatidylinositols was directly associated with secretagogues inducing calcium movements.

Amylases↗
PubMed1979

In vitro lipid metabolism in the rat pancreas. I. Basal lipid metabolism.

1. The in vitro basal lipid metabolism of rat pancreatic fragments was compared with that in adipose tissue fragments and liver slices. 2. [1-14C]Acetate added to the media was mostly incorporated into palmitic acid and to a lesser extent into oleic acid. In addition, pancreatic tissue exhibited a marked capacity for elongation of polyunsaturated fatty acids by [1-14C]acetate and resulting desaturation when compared to adipose tissue and liver. 3. Data obtained in the presence of [U-14C]glucose, [1-14C]palmitate and 3H20 indicate that acetyl-CoA derived from glucose and from beta-oxidation of fatty acids contributed to de novo lipogenesis. 4. Oxidation of [1-14C]palmitic acid was 9-13 times higher in the pancreas than in adipose tissue or liver when expressed on a wet weight basis. 5. The fatty acid moiety of pancreatic glycerolipids could be derived from de novo synthesis, fatty acids added to the medium, or from fatty acids formed from the hydrolysis of endogenous lipids. The glycerol moiety could be derived either from glucose, or directly from glycerol through participation of glycerol kinase.

Acetates↗
PubMed1979

In vitro lipid metabolism in the rat pancreas. II. Effects of secretagogues on fatty acid metabolism, net lipolysis and ATP levels.

1. The concentration of carbamylcholine, bombesin, pancreozymin, pentagastrin and secretin evoking a similar 4--5-fold maximal increase in amylase secretion from rat pancreatic fragments were 3.10(-6), 10(-7), 10(-8), 3.10(-6), and 3.10(-6) M, respectively. The maximal concentration of vasoactive intestinal peptide tested (3.10(-6) M) increased amylase secretion by 250%. The six secretagogues could be separated into two groups according to their effects on lipid metabolism and ATP levels. 2. When used at their optimal concentrations, carbamylcholine, bombesin, pancreozymin, and pentagastrin lowered pancreatic ATP levels by 18-26% and increased net release of free fatty acids by 68-105%. 3. The effects of 3.10(-6) M carbamylcholine and 10(-8) M pancreozymin on the metabolism of 3H2O, D-[U-14C]glucose and [1-14C]acetate were similar; the incorporation of radioactivity in the fatty acid moiety of glycerolipids decreased by 20--50% whereas the incorporation of 3H from 3H2O and of 14C from [U-14C]glucose increased by 20--35% in the glycerol moiety. In addition, the oxidation of [U-14C]glucose, [1-14C]acetate and [1-14C]palmitate to 14CO2 increased by 15--32% while the esterification of [1-14C]palmitate, [1-14C]-linoleate, and [1-14C]arachidonate was inhibited by 14--23%. The spectrum of fatty acids labeled with [1-14C]acetate indicated an inhibition of the malonic acid pathway whereas the elongation of polyenoic fatty acids was unaltered.

Acetyl Coenzyme A↗
PubMed1979

In vitro lipid metabolism in the rat pancreas. III. Effects of carbamylcholine and pancreozymin on the turnover of phosphatidylinositols, 1,2-diacylglycerols and phosphatidylcholines.

1. The turnover of phosphatidylinositols and other glycerolipids was examined in rat pancreatic fragments incubated in the presence of carbamylcholine and pancreozymin used at a concentration inducing maximal alpha-amylase hypersecretion. 2. In stimulated tissue, [1-14C]acetate-labeled fatty acids were incorporated into phosphatidylinositols, 1,2-diacylglycerols, and phosphatidic acids in preference to phosphatidylcholines, phosphatidylethanolamines, triacylglycerols, monoacylglycerols, and free fatty acids. Variations in the percent distribution of 14C among fatty acids and in specific activity of individual fatty acids in each lipid class suggested that the secretagogues reduced selection of newly synthesized 1,2-diacylglycerols which occurred in the resting state before their incorporation into phosphatidylinositols. Secretagogues also promoted recycling of endogenous 1,2-diacylglycerols (produced from hydrolysis of unlabeled glycerolipids) for the biosynthesis of phosphatidylinositols. 3. Increased rate of incorporation of [1-14C]palmitate, [1-14C]linoleate, [1-14C]arachidonate and [1(3)(n)-3H]glycerol into phosphatidylinositols was detrimental to phosphatidylcholines. 4. The lipolytic effects of carbamylcholine and pancreozymin as illustrated by the release of 1,2-diacylglycerols and free fatty acids, were markedly inhibited in calcium-free medium enriched with 1 mM EGTA but increased turnover of phosphatidylinositols as determined from incorporation of radioactive precursors was only moderately affected.

Animals↗