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Biomedical subjects

J Guerrero

Publications and source records attributed to J Guerrero.

At least 55 records · Page 3Linked to original sources
PubMed1993

Mathematical models for the population biology of Ostertagia ostertagi and the significance of aggregated parasite distributions.

Parasite frequency distributions are frequently aggregated. Such distributions are conveniently described using the negative binomial frequency distribution. This distribution is completely characterized by two parameters: the mean of the distribution and an exponent, k. The degree of aggregation is inversely proportional to the value of k. Aggregated parasite distributions enhance the ability of regulatory processes to maintain parasite populations at or near their equilibrium level but incorporating parasite frequency distributions in realistic models of parasite population biology is fraught with difficulty (several simplified examples are given). Indeed, it is not always possible to incorporate parasite frequency distributions and the question arises whether this compromises model performance. Trichostronglyid nematodes, including Ostertagia ostertagi, are aggregated but the estimated value of k for such populations is usually greater than 1. This is typical of populations with high population means (tens of thousands). It is shown that when the degree of aggregation is such that k > 1, the results of a model which recognizes parasite frequency distribution is not much different from the results of a model which assumes all hosts contain exactly the same number of parasites.

Animals↗
PubMed1992

[Polyarteritis nodosa in a woman with temporal arteritis].

A case of a 74-year-old woman, with a histological diagnosis of Transient Arteritis two years before and Nodose Polyarteritis, is described. Although the coexistance of these two vasculitis in a same patient has been rarely described in the literature, we considered that the diagnostic suscpiction of Nodose Polyarteritis should be maintained in a patient with Transient Arteritis developing multisystemic signs.

Aged↗
PubMed1990

[The effect of the day of parturition in the technological cycle of maternity on the morbidity of diarrhea in lactating piglets].

The study investigated the frequency of piglet diarrhoea from birth to weaning (33rd day) in a farrowing pigsty with 3 rows of boxes during 7 rearing cycles with 240 piglets each, always related to the day of birth in connection with the onset of the cycle. 3 groups were differentiated according to the day of birth: 3 and 4, 5, 6 and 7, based on the disposition of the sow. Also investigated was the position of the litters in the middle or one of the marginal rows of boxes of the pigsty. The germ density of the air during 2 cycles each of the rainy and dry seasons was investigated in the empty pigsty as well as after the 6th day of occupation by means of sedimentation in endo agar. A significant influence was found of the day birth (p less than 0.05) and of the interaction of row of boxes and day of birth (p less than 0.05) as well as the row of boxes and season (p less than 0.05) on the morbidity and mortality due to piglet diarrhoea. The higher levels occurred in the groups of animals born later and housed in the central row of boxes. The number of units forming colonies increased significantly (p less than 0.05) in 10 cm2/min samples on endo agar from the 0th to the 6th day of the cycle and reached 100% of the samples from which also E. coli K 88 was isolated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Educational and research program on diagnosis and treatment of otitis media in Latin America].

Otitis media in Latin America is an important cause of hearing impairment and infectious complications which can be prevented without an inordinate effort or investment of resources. The Latin American Otitis Media Research and Training Program is a multidisciplinary, international project designed to improve the detection an treatment of otitis media in Latin America. Over 200 health care providers have already participated in pilot seminars presented in Brazil, Costa Rica, and Mexico. These sessions were highlighted by audiovisual presentations emphasizing pneumatic otoscopy. We conclude that this focused program of medical education can significantly contribute to improve primary health care in the region.

Adolescent↗
PubMed1988

Effects of propafenone on ventricular arrhythmias: double-blind, parallel, randomized, placebo-controlled dose-ranging study.

Propafenone is a new class Ic antiarrhythmic compound with a broad pharmacologic profile. In this study, its dose-response relationship was examined in a double-blind, randomized, placebo-controlled five treatment parallel design protocol. Patients enrolled had heart disease with Lown grade 2 premature ventricular contractions (PVCs) (greater than or equal to 30/hr) documented on 24-hour Holter recordings. Propafenone was compared in four doses (337.5, 450, 675, and 900 mg/day) to placebo. The double-blind phase lasted 2 weeks. Two hundred twenty-six patients were enrolled, of whom 171 were men and 55 were women; their mean age was 59.8 years and 85% were Caucasian and 4% were black. The arrhythmias were symptomatic in 173. Twenty (8.8%) withdrew from the study before completion: 15 had adverse reactions, two had intercurrent illnesses, and three withdrew for administrative reasons. In one patient, the density of arrhythmia appeared to increase with propafenone. Side effects were of central nervous system or gastrointestinal origin; less than 5% of patients developed first-degree atrioventricular block or intraventricular conduction defect. There were no deaths in the study. The occurrence of side effects was not related to dose. Propafenone had no effect on heart rate. It increased the PR interval at all doses (9% to 22% compared to placebo at baseline; p less than 0.01) at 450 to 900 mg/day after 2 weeks of therapy. The drug increased the QRS duration at all doses, highly significantly at 675 mg/day (8.5 msec; p less than 0.01) and at 900 mg/day (15.7 msec; p less than 0.01) after 2 weeks of therapy. Only at the highest dose was the QTc slightly but significantly (14.3 msec; p less than 0.01) increased. Propafenone exerted a dose-dependent effect on PVCs recorded on serial 24-hour Holter recordings: compared to placebo, at 2 weeks 337.5 mg/day reduced PVCs by 70.8% (p less than 0.05), 450 mg/day reduced PVCs by 82.0% (p less than 0.01), 675 mg/day reduced PVCs by 90.2% (p less than 0.01) and 900 mg/day reduced PVCs by 95.3% (p less than 0.01). The effects of the two highest doses of propafenone were significantly greater than those of 337.5 mg/day. In 68% of the patients receiving 900 mg/day, 80% or greater reduction in total PVCs was found. In addition, there was a greater than 90% decrease in ventricular couplets, and 96% decrease in ventricular tachycardia (VT) beats. Propafenone eliminated PVCs in 8% of all patients, ventricular couplets in 58%, and VT beats in 91%.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1987

Ancrod decreases the frequency of cyclic flow variations and causes thrombolysis following acute coronary thrombosis.

The potential use of ancrod, a purified isolate from the venom of the Malaysian pit viper, Agkistrodon rhodostoma, in decreasing the frequency of cyclic flow variations in severely stenosed canine coronary arteries and causing thrombolysis of an acute coronary thrombus induced by a copper coil was evaluated. Open-chest, anesthetized dogs were used. Ancrod was given intravenously (8 U/kg) over 1 hour and caused a significant reduction in the frequency of cyclic flow variations (5.8 +/- 0.7 to 3.6 +/- 0.8 cyclic flow variations per 30 minutes, p less than 0.05), whereas control animals failed to decrease the frequency of their cyclic flow variations over the same time period (5.3 +/- 0.3 to 5.0 +/- 0.4 cyclic flow variations per 30-minute period). Twenty-seven dogs had a coronary thrombus induced by a copper coil positioned directly in a major coronary artery; of these, four died of ventricular fibrillation prior to treatment, eight received an infusion of saline and showed no thrombolysis over 5 hours, and three died of ventricular fibrillation during the initial part of an intravenous infusion of ancrod. The remaining 12 dogs received ancrod intravenously (16 U/kg); six demonstrated lysis of the coronary thrombus (mean time to lysis, 65 +/- 20 minutes). The concentrations of ancrod used in these studies produced a severe decrease in systemic fibrinogen concentration and a significant decrease in the inhibitor of plasminogen activator levels. Thus, ancrod decreases the frequency of cyclic flow variations in stenosed canine coronary arteries and may cause coronary thrombolysis in approximately 50% of animals within 65 +/- 20 minutes of its intravenous administration.

Acute Disease↗
PubMed1987

Serum protein binding of sulfisoxazole and diazepam in patients with chronic obstructive pulmonary disease.

Binding of two acidic drugs, sulfisoxazole and diazepam, to serum proteins has been investigated in patients with chronic obstructive pulmonary disease and in a control group of healthy volunteers. Marked increases in the free fraction of both drugs in serum were detected in patients (14.5 +/- 0.8% versus 6.1 +/- 0.3% in the case of sulfisoxazole, and 5.8 +/- 0.5% versus 3.2 +/- 0.0% in the case of diazepam). Decreased serum albumin concentration appeared to play a role in the defective binding of sulfisoxazole, although when this factor was corrected, some correlation between serum binding of sulfisoxazole and PaO2 values was detected. Other factors have to be considered to explain the decreased binding of diazepam in the serum of patients with chronic obstructive pulmonary disease.

Aged↗
PubMed1986

Seasonal comparisons of anthelmintic activity of levamisole pour-on in cattle in the USA.

Anthelmintic activity of a pour-on formulation of levamisole, applied during warm weather (16 degrees to 36 degrees C) at 10 mg/kg bodyweight, was evaluated in groups of naturally parasitised calves. This activity was compared to that obtained in similar groups of calves treated in the winter (-4 degrees to +7 degrees C). Controlled efficacy of the pour-on formulation was determined for each season by comparing mean worm burdens in treated calves sacrificed seven to nine days after treatment to non-treated controls. In these trials, burdens of Bunostomum phlebotomum, Cooperia species, Haemonchus placei, Nematodirus species, Oesophagostomum radiatum, Ostertagia ostertagi and Trichostrongylus axei in treated calves were reduced by 83.3 to 100 per cent in the summer and 89.2 to 100 per cent in the winter. Field investigations at nine locations across the USA compared changes in faecal egg counts for cattle treated and evaluated during warm summer months (27 degrees to 36 degrees C) to those treated during cold winter months (-18 degrees to +10 degrees C). Overall, faecal egg counts were reduced by 90.2 per cent in the summer trials and 94.0 per cent in the winter trials. The results of these trials indicate that there is no seasonal variation in the anthelmintic activity of this pour-on formulation of levamisole.

Animals↗
PubMed1985

Activity of closantel in the prevention of Gasterophilus and Strongylus vulgaris larval infections in equine foals and yearlings.

Two controlled tests were conducted in equine foals and yearlings to determine the optimal oral dosage and the duration of activity of closantel for the prevention of Gasterophilus spp larval infections. Additional data were collected on the activity of closantel against Strongylus vulgaris larval infections. In experiment 1, 12 foals and 12 yearlings were equally allocated to 4 experimental groups, and were given oral treatments with closantel at dosages of 0 (nontreated controls), 2, 5, or 8 mg/kg of body weight every 2 months during bot season. The foals and yearlings were allowed to graze on open pasture throughout the experiment to provide a natural source for bot and helminth infections. All animals were euthanatized and necropsied 6 weeks after the final treatment. Closantel was highly effective (98.6% to 100%) at all doses in preventing Gasterophilus spp larval infections in the foals, but only the 8 mg/kg dose had significant (P less than 0.05) activity (99.7%) in the yearlings. This dose also significantly reduced the numbers of 4th-stage and immature adult S vulgaris (86.0%) in the mesenteric arteries as compared with nontreated controls. In experiment 2, 9 foals and 9 yearlings received a single oral treatment of 8 mg of closantel/kg of body weight; 3 foals and 3 yearlings were kept as nontreated controls. Groups of 6 treated (3 foals, 3 yearlings) and 2 control (1 foal, 1 yearling) animals were euthanatized and necropsied 1, 2, and 3 months after treatment. Closantel remained effective for 2 months in preventing infections of G intestinalis larvae in these foals and yearlings. Clinical signs of toxicosis were not observed in the treated animals of either study.

Animals↗
PubMed1984

Anthelmintic efficacy of mebendazole suspension against induced helminth infections in South African sheep and cattle.

Critical controlled tests were performed in 157 sheep (8 experiments) and 34 cattle (2 experiments) to evaluate the anthelmintic activity of mebendazole suspension, administered intraruminally via a stomach tube at a dosage rate of 15 mg of mebendazole/kg of body weight, against induced infections of immature and adult stages of commonly encountered nematode parasites in South Africa. In the sheep, the controlled efficacy of mebendazole suspension was good to excellent (90.1% to 100%) against all stages of Haemonchus contortus, Trichostrongylus colubriformis, Gaigeria pachyscelis, Ostertagia circumcincta, Nematodirus spathiger, and Chabertia ovina species. Mebendazole was also highly effective (97.3% to 99.9%) against 4th, 5th, and adult stages of Oesophagostomum columbianum and 5th-stage and adult Dictyocaulus filaria. Moderate activity was obtained (79.8% to 82.2%) against 3rd-stage O columbianum, 3rd- and 4th-stage D filaria, and 5th-stage and adult Strongyloides papillosus. In the cattle, mebendazole was effective (91.5% to 100%) against 4th-stage and adult H placei, Cooperia pectinata, Bunostomum phlebotomum, and Oesophagostomum radiatum species, but did not exhibit any appreciable activity (27.3% to 41.5%) against 4th-stage and adult O ostertagi.

Administration, Oral↗
PubMed1984

Controlled and clinical evaluations of the anthelmintic activity of a levamisole pour-on formulation against gastrointestinal nematodes in cattle.

Beef-type calves (n = 107) with naturally occurring helminth infections were used in a series of 3 controlled experiments to study the anthelmintic activity of a new pour-on formulation of levamisole. In the 1st experiment, the efficacy of a single treatment of levamisole pour-on at a rate of 10 mg/kg of body weight was determined, using a placebo pour-on in a similar volume as a control. In the 2nd experiment, calves were treated with levamisole pour-on at doses 0 (nontreated control), 7.5, 10, or 12.5 mg/kg of body weight. In the 3rd experiment, the anthelmintic efficacy of the optimal dose of levamisole pour-on (10 mg/kg of body weight) was compared with that of injectable levamisole at the recommended rate (6 mg/kg of body weight). In all 3 studies, levamisole pour-on, at a dosage of 10 mg/kg of body weight, was efficacious (90% to 100%) against the adult forms of Trichostrongylus axei, Haemonchus placei, Ostertagia ostertagi, Cooperia spp, Oesophagostomum radiatum, Nematodirus spp, and Bunostomum phlebotomum. Efficacy was moderate to good against Capillaria bovis, and poor or inconsistent against Strongyloides papillosus and Trichuris ovis. Clinical tests of anthelmintic efficacy and local tolerance of levamisole pour-on were conducted in 371 beef and dairy cattle in Mexico. Fecal egg counts were consistently reduced 2 weeks after a single application of levamisole pour-on at a dosage of 10 mg/kg of body weight. Local reactions were limited to various degrees of dry hair coat for up to 2 weeks at the application site. Hair loss or skin abnormalities were not observed in any of the treated cattle.

Animals↗
PubMed1983

Verapamil improves exercise capacity in chronic atrial fibrillation: double-blind crossover study.

Oral verapamil has previously been shown to reduce heart rate at rest and during mild exercise in chronic atrial fibrillation. Its efficacy in improving cardiovascular performance at higher levels of exercise and its safety were investigated in a prospective, randomized, placebo controlled double-blind study preceded by an open label titration phase in 20 digitalized patients with chronic atrial fibrillation. Maximal exercise capacity was improved (from 522 +/- 257 to 806 +/- 348 work units, p less than 0.0005) when tested by a standardized multistage ergometry exercise test. Heart rate was also reduced at rest, at the end of 3 minutes of 300 KPM exercise, and at the point of maximal exercise. Blood pressure and double product were also reduced. Its efficacy and safety may make verapamil the treatment of choice in chronic atrial fibrillation.

Adult↗
PubMed1983

The activity of closantel as an equine antiparasitic agent.

Eighteen pony foals were experimentally infected with 500 third stage larvae of Strongylus vulgaris at 2 weeks, and at 2, 4, 6 and 8 months after birth. For the duration of the study, all foals were kept in the same pasture with their mothers to allow natural infection with other parasites by exposure to a contaminated environment. Twelve of the foals were utilized in groups of 3 and treated orally five times at two month intervals starting at one month of age with closantel at doses of 5, 10, 20 or 40 mg kg-1. Ten months after birth the foals were necropsied to determine the parasitic burdens in the gastrointestinal tracts and the cranial mesenteric arteries. The results indicate a high antiparasitic activity of closantel against larval stages of Gasterophilus intestinalis and S. vulgaris, as well as against adult S. vulgaris, S. edentatus, Anoplocephala perfoliata and Triodontophorus spp., when used at doses of 20 or 40 mg kg-1.

Animals↗
PubMed1983

The acute hemodynamic effects of intravenous verapamil in coronary artery disease. Assessment by equilibrium-gated radionuclide ventriculography.

The acute hemodynamic effects of an i.v. bolus of verapamil, 0.1 mg/kg or 0.06-0.075 mg/kg, were examined by serial radionuclide studies in 46 patients with coronary artery disease. In 20 patients with ejection fractions (EFs) greater than 35% (group 1A), verapamil, 0.1 mg/kg given over 1-11/2 minutes, had a biphasic effect: first, a transient decrease in EF accompanied by increased left ventricular (LV) volumes and cardiac output equivalents; then, an overshoot of EF to values above control, accompanied by a decrease in peripheral vascular resistance and a drastic decrease in LV volumes, while cardiac output equivalent remained slightly elevated. In eight patients with EFs less than 35% (group 1B), only the first effect on EF was noted. In 10 patients with EFs greater than 35% (group 2), verapamil, 0.06-0.075 mg/kg, exerted qualitatively similar but milder effects on hemodynamic function. Finally, verapamil, 0.1 mg/kg given more slowly, over 2-21/2 minutes, produced no significant changes in EF or LV volumes in another eight patients (group 3). The acute effects of verapamil are thus both time-related and dose-dependent. They are also related to the baseline functional reserve of the left ventricle. This study documents that verapamil exerts a depressant effect on LV function. However, the transient nature of this depression and the quick recovery to normal or above-normal values indicate that verapamil, in the doses used in this study, is safe to use intravenously in patients with coronary artery disease.

Adult↗
PubMed1983

Superiority of oral verapamil therapy to digoxin in treatment of chronic atrial fibrillation.

The efficacy and safety of oral verapamil, 240 mg, with or without digoxin were studied in 52 patients with chronic atrial fibrillation at rest, and during mild and maximal exercise. Twenty-four patients were studied during the following therapeutic modalities: no therapy; digoxin, 0.25 mg and 0.5 mg daily; digoxin, 0.25 mg and verapamil; and verapamil alone. Heart rate at rest and during all levels of exercise was decreased significantly (p less than 0.005), either by combining digoxin with verapamil or by verapamil therapy alone. In contrast, the excessive heart rate response to exercise was not prevented by digoxin even with good serum concentrations. The improved control of heart rate with verapamil was associated with a significantly improved exercise capacity. Verapamil is an important and safe modality of treatment, with or without digoxin, in the long-term control of heart rate in chronic atrial fibrillation. It is superior to digoxin in controlling the ventricular rate and in improving exercise capacity.

Administration, Oral↗