Search PubMed⌕ Search

Biomedical subjects

J Roca

Publications and source records attributed to J Roca.

At least 217 records · Page 12Linked to original sources
PubMed1993

Preventing asthma epidemics due to soybeans by dust-control measures.

BACKGROUND: The inhalation of soybean dust released during the unloading of soybeans into a silo caused outbreaks of asthma in Barcelona, Spain. This study was designed to determine morbidity due to asthma and serum IgE reactivity before and after the installation of filters in the silo. METHODS: We measured soybean-allergen concentrations in 136 samples of air collected for 9 months before and 24 months after the installation of filters. We compared the number of days on which there was an unexpected increase in emergency room visits for asthma, the number of days on which the number of emergency room visits for asthma in one four-hour period was so high that it was unlikely to be due to chance, and the mean daily number of emergency room and intensive care unit admissions for asthma for a total of 60 months before and after filter installation. Serum IgE antibodies against soybean allergens were measured in 38 patients before and after filter installation. RESULTS: The concentration of airborne soybean allergens on days when soybeans were unloaded decreased from 324 to 25 U per cubic meter after the installation of filters (P < 0.001). The number of days on which there was an unusually large number of visits to the hospital for asthma and the number of days on which asthma was epidemic both decreased significantly (both P < 0.001), from 29 to 6 and from 18 to 0, respectively. The mean daily number of emergency room and intensive care unit admissions for asthma on days when soybeans were unloaded decreased from 8.3 to 5.4 and from 0.26 to 0.01, respectively (both P < 0.001). The mean serum IgE antibody concentrations in the 38 patients studied decreased from 2 Pharmacia reference units per milliliter to 1 (P < 0.001). CONCLUSIONS: Installing filters on silos to prevent airborne dissemination of allergenic soybean dust eliminates outbreaks of asthma caused by inhalation of the dust, thus supporting the idea that the avoidance of allergens helps prevent asthma.

Adolescent↗
PubMed1993

Novel antagonists of 5-HT3 receptors. Synthesis and biological evaluation of piperazinylquinoxaline derivatives.

A series of piperazinylquinoxalines has been synthesized and studied as 5-HT3 receptor antagonists in different preparations. Antagonism to 5-HT in the longitudinal muscle of the guinea pig ileum was particularly prominent in cyanoquinoxaline derivatives with an alkyl substitutuent on the piperazine moiety. The pA2 of some selected compounds against the 5-HT3 agonist 2-methyl-5HT in the guinea pig ileum was in the range of tropisetron or ondansetron, and one of them, 7e, was more potent than these reference compounds by approximately 2 or 3 orders of magnitude. However, these compounds were markedly less potent than either tropisetron or ondansetron as displacers of 3H-BRL 43694 binding to rat cortical membranes or as antagonists of the Bezold-Jarisch reflex in rats. Piperazinylcyanoquinoxalines represent a new class of 5-HT3 antagonists with a selective effect on guinea pig peripheral receptors.

Animals↗
PubMed1993

On the simultaneous binding of eukaryotic DNA topoisomerase II to a pair of double-stranded DNA helices.

Stabilization of crossings of pairs of DNA helices by binding of eukaryotic DNA topoisomerase II was studied by two types of experiments. In one, mixtures of yeast DNA topoisomerase II and supercoiled DNA were incubated with vaccinia virus topoisomerase, and the linking numbers of the DNA products were measured to quantitate supercoils that were constrained by the stoichiometrically bound yeast enzyme molecules; in parallel, the same yeast enzyme-supercoiled DNA mixtures were incubated with a nonhydrolyzable ATP analog AMPPNP (adenosine 5'-(beta, gamma-imido)triphosphate) instead of the vaccinia enzyme, and DNA linking number changes following the addition of AMPPNP were measured to monitor DNA transport mediated by the yeast enzyme and AMPPNP. In the second type of experiments, formation of knotted DNA rings by the addition of AMPPNP to mixtures of yeast DNA topoisomerase II and different topological forms of DNA rings was studied. These experiments indicate that binding of yeast DNA topoisomerase II to DNA crossings is significant, especially in low salt media containing Mg(II), and that this mode of binding strongly affects DNA knotting. It appears, however, that stabilization of DNA crossovers by the eukaryotic type II enzyme is not directly related to its DNA transport activity.

Adenylyl Imidodiphosphate↗
PubMed1993

Separation of rooster spermatogenic nuclei by means of centrifugal elutriation.

By application of minor variations in the usual method of centrifugal elutriation, we have been able to separate a nuclear suspension from rooster testes. We have obtained a population of elongated or late spermatid nuclei (98% purity), a population of round or early spermatid nuclei (90% purity), and, finally, a mixed population of meiotic and pre-meiotic nuclei.

Animals↗
PubMed1993

Acrosome reaction of boar spermatozoa in homologous in vitro fertilization.

Ejaculated spermatozoa from four different boars were used to evaluate the acrosome reaction during in vitro fertilization with homologous ovulated oocytes. The acrosome reaction was assessed according to a peroxidase-labeling peanut agglutinin method and a triple-stain technique. An increase in the proportion of living sperm with reacted acrosomes was observed after preincubation and 2 hr of coincubation (P < 0.05). The percentage of true acrosome-reacted sperm remained reasonably constant throughout coincubation. In vitro penetration rates of oocytes varied among boars, but no relationship was found between fertilization rates of oocytes and maximum percentages of acrosome reacted living sperm.

Acrosome↗
PubMed1993

The results of surgical treatment of lumbar arachnoiditis.

Forty patients with lumbar arachnoiditis, following previous operations, were classified into 4 myelographic types. Most patients with type I images had herniated disc symptoms with unilateral leg pain and limited straight-leg raising. Patients with types II and III myelographic appearances had bilateral leg pain, absent ankle jerks, weakness, cramps and signs of diffuse sensory deficit; some also had neurogenic claudication and urinary sphincter dysfunction. All patients with type IV had dysesthesia. Twenty-three of the 40 patients underwent reoperation and those with types I and II had acceptable results, but poor results occurred in those with types III and IV myelograms.

Adult↗
PubMed1993

In vitro fertilization of pig oocytes after different coincubation intervals.

The effects of gamete coincubation time on porcine in vitro fertilization for 4, 6 or 8 hours in Trial 1 or for 1, 2, 3 or 4 hours in Trial 2 were studied. The 876 oocytes were recovered from oviducts of prepubertal gilts. Ovulation was induced. Excessive spermatozoa attached to zona pellucida were removed by pippeting after coincubation (1 to 8 hours). Optimum results were obtained after 3 to 4 hours of coincubation, when 23 to 29% of the oocytes were fertilized by a single spermatozoa. Shorter intervals of coincubation were characterized by reduced percentages of fertilized oocytes and longer intervals of coincubation by increased rates of polyspermic fertilization. The employed sperm concentration was deliberately high (2 x 10(6) sperm/ml). The results show that a coincubation time of 4 hours may be optimal for pig in vitro fertilization. Under these assay conditions, modification of other factors such as sperm concentration, medium volume and physiological environment may increase the percentage of monospermic fertilization.

Journal Article↗
PubMed1993

Sperm concentration influences fertilization and male pronuclear formation in vitro in pigs.

To study the effect of sperm concentration on the results of pig in vitro fertilization (IVF), 313 oocytes recovered from oviducts of prepubertal gilts after induction of ovulation were used. After capacitation, the number of live spermatozoa in the fertilization dishes was adjusted to 3 x 10(5), 6 x 10(5) and 12 x 10(5) cell/ml. After 4 hours of co-culture in TCM-199, the oocytes were pippeted to remove cumulus cells and the excess spermatozoa around the zona pellucida, and were transferred to fresh TCM-199 for another 12/14 hours. The results showed that 6 x 10(5) spermatozoa/ml is the optimum concentration for this system; the percentage of fertilized ova (71.6%) was not different from the best (76.8%), that was obtained with the highest concentration, and the percentage of monospermy (62.3%) was not different from the best (68.1%), that was obtained with the lowest concentration. The percentage of spermatozoa that reached the pronuclear stage increased while sperm concentration was decreased. The percentage of spermatozoa at the decondensed stage was decreased when the sperm concentration increased.

Journal Article↗
PubMed1993

Evaluation of boar spermatozoa penetrating capacity using pig oocytes at the germinal vesicle stage.

We evaluated the ability of immature pig oocytes (at germinal vesicle stage) to detect differences in the in vitro penetration rates of boar spermatozoa. In Experiment 1, immature and ovulated oocytes (n=303) were exposed to capacitated boar spermatozoa to determine if the penetrability of immature pig oocytes was comparable to that of ovulated oocytes. The percentages of penetrated oocytes and the mean number of spermatozoa per oocyte were similar for immature (88.82 and 7.42+/-0.41) and ovulated oocytes (90.97 and 7.95+/-0.34, respectively). In Experiment 2, immature oocytes (n=1230) were inseminated with semen from 2 boars (A and B) with satisfactory semen characteristics to establish the variability of in vitro penetrating capacity between the boars. Semen was examined for motility, movement quality, acrosome integrity and plasma membrane integrity at various stages of the in vitro procedure. Although the sperm evaluation results were similar between boars, Boar A exhibited a significantly higher (P<0.001) penetration rate (91.49%) and number of spermatozoa penetrated per oocyte (5.90+/-0.25) than Boar B (52.87% and 2.03+/-0.12, respectively). Increasing the sperm concentration at insemination from 1 x 10(6) to 10 x 10(6) cells/ml resulted in an increased penetrating capacity for both boars, and the differences in the number of spermatozoa per oocyte between boars also increased. These results indicate that immature pig oocytes can be used in a homologous in vitro fertilization assay, and that despite similarities in semen characteristics a significant boar effect is evident for parameters of in vitro penetration of oocytes.

Journal Article↗
PubMed1993

Environment and medium volume influence in vitro fertilisation of pig oocytes.

Oviductal oocytes (n = 795) were obtained from ovulation-induced prepubertal gilts. In the first experiment, different parameters related to in vitro fertilisation (IVF) were compared in the presence and absence of cumulus matrix (which is shed with the oocytes at ovulation). The results show that the presence of this matrix is beneficial because the rates of fertilisation (69%) and monospermy (number of monospermic oocytes/total number of healthy mature oocytes; 42%), and the median number of spermatozoa per oocyte (1.52 +/- 0.06), were improved with respect to those obtained in its absence (54%, 22% and 2.33 +/- 0.08, respectively; p < 0.01). In the second experiment the effect of two different volumes of co-incubation medium (2 ml and 0.4 ml) on the same parameters of porcine IVF were compared. No significant differences between volumes were observed, except in the mean number of spermatozoa per oocyte and the percentage of dispermic oocytes.

Animals↗
PubMed1993

Effects of adrenaline on ventricular function and coronary haemodynamics in relation to catecholamine handling in transplanted human hearts.

We investigated cardiovascular and coronary responses to intravenous infusions of adrenaline, which raised arterial concentrations in a stepwise fashion from basal to about 5-6 nmol.l-1, in 11 non-rejecting heart transplanted patients, and in eight intact innervated subjects. Cardiac adrenaline extraction and noradrenaline release rate were also measured. The transplanted patients showed larger increases in heart rate (36 +/- 11% vs 16 +/- 6%, P < 0.0001) and cardiac index (80 +/- 30% vs 56 +/- 19%, P < 0.05), while stroke volume increments were similar in the two groups (32 +/- 17% vs 35 +/- 13%). The study groups did not differ with respect to changes in arterial pressure, cardiac work or peripheral resistances. Coronary sinus blood flow increased to a greater extent in the transplanted group (75 +/- 35% vs 48 +/- 31%, P < 0.05) and myocardial oxygen consumption also tended to increase more in these patients (78 +/- 42% vs 48 +/- 34%, NS). Myocardial adrenaline extraction was greatly reduced in the transplant patients (-6 +/- 25% vs 64 +/- 18%, P < 0.001), while forearm adrenaline extraction was similar in the two groups (41 +/- 22% vs 40 +/- 23%, NS). Cardiac noradrenaline overflow tended to be lower in the transplanted group (12 +/- 62 vs 48 +/- 43 pmol.min-1, NS). There was a wide range of noradrenaline overflow values (-64 to 147 pmol.min-1) and definite high values in three patients. Cardiac noradrenaline overflow was not correlated to heart rate responsiveness to adrenaline. We conclude that patients with cardiac transplantation respond to adrenaline with exaggerated increases in heart rate and thus in cardiac output. High values of cardiac noradrenaline overflow are seen in some transplant recipients and may suggest reinnervation. Signs of reinnervation are not associated with consistently lower heart rate responses to beta-adrenergic stimulation.

Adult↗
PubMed1993

Airway obstruction and ventilation-perfusion relationships in acute severe asthma.

We have investigated the time course of ventilation-perfusion (VA/Q) mismatch and airflow obstruction in 18 patients with acute severe asthma with the objective to identify potential differences according to the clinical severity of the attacks. Nine patients were hospitalized and nine were discharged (emergency room stay < 24 h) according to the clinical criteria of the attending physicians. Spirometry and VA/Q inequality (multiple inert gas technique) were measured within the first 6 h of treatment in the emergency room, and at Weeks 1,2,3, and 4 thereafter. In the emergency room [corrected] hospitalized patients (in relation to those discharged) showed lower airflow rates (FEV1, 31 +/- 3 versus 46 +/- 6% predicted SEM) and greater VA/Q mismatch (as assessed by the dispersion of blood flow distributions (logSD Q) (1.28 +/- 0.11 versus 0.92 +/- 0.11; normal values < 0.6). Even though the rate of improvement of airflow was similar in both groups (without returning to normal limits), VA/Q relationships improved at different rates in each group and reached normal values at the end of the study. Although in hospitalized patients the recovery of VA/Q abnormalities was delayed in relation to airflow rates, the time course in discharged patients was the same. Previous studies have shown a dissociation between spirometry and VA/Q inequality, suggesting that whereas airflow rates predominantly reflect bronchoconstriction of large airways, VA/Q mismatch is more related to obstructive changes in peripheral airways. Our results support this hypothesis and suggest that the more severe the asthma attacks, the more severe the obstructive changes involving peripheral airways for a given degree of widespread airway narrowing.

Acute Disease↗
PubMed1993

[Multiple antibiotic resistance in Haemophilus influenzae related to serogroup B].

AIM: To study the association between multiply antibiotic resistance in Haemophilus influenzae and H. influenzae type B, and to describe levels and patterns of antibiotic resistance. METHODS: Statistical analysis and susceptibility of 231 H. influenzae strains (52 type B and 179 non-typable ) isolated consecutively from pediatric patients. RESULTS: Resistance levels for type B and non-typable strains were: Ampicillin, 55.3% vs 28.8%; Chloramphenicol, 44.7% vs 9.2%; Ampicillin plus chloramphenicol, 40.4% vs 7.6%; cotrimoxazole, 89.3% vs 67.4%; resistance to six or more antibiotics, 36.0% vs 3.8%. CONCLUSION: Multiply antibiotic resistance in H. influenzae is strongly associated with type B strains, with age of 4 or younger, and with isolation from CSF or blood. Resistance is sustained over long periods of time.

Child, Preschool↗
PubMed1993

BAL lymphocyte activation antigens and diffusing capacity are related in mild to moderate pulmonary sarcoidosis.

To investigate the relationship [corrected] between immunocytological features of bronchoalveolar lavage (BAL) and clinical indices in sarcoidosis, we studied the lymphocyte subsets, as well as the expression of human leucocyte antigen-DR (HLA-DR) and interleukin 2 receptor (IL-2R) antigens in BAL lymphocytes. We studied 16 patients with untreated sarcoidosis and 12 control subjects. We found significantly higher absolute numbers of lymphocytes bearing the IL-2R antigen in sarcoidosis. A stronger difference between groups was observed in both the percentage and absolute numbers of HLA-DR+ lymphocytes. We also found a moderate but significant correlation between the number of lymphocytes expressing the activation antigens and single breath carbon monoxide diffusing capacity in patients with sarcoidosis: DLCO vs HLA-DR+ lymphocytes (r = -0.60); DLCO vs IL-2R+ lymphocytes (r = -0.62); carbon monoxide transfer coefficient (KCO vs HLA-DR+ lymphocytes (r = -0.53); and KCO vs IL-2R+ lymphocytes (r = -0.58). Our results suggest that the reduction in diffusing capacity, expressed as either DLCO or KCO, results from the severity of alveolitis in mild to moderate sarcoidosis.

Adult↗
PubMed1992

The capture of a DNA double helix by an ATP-dependent protein clamp: a key step in DNA transport by type II DNA topoisomerases.

The binding of linear and circular forms of DNA to yeast DNA topoisomerase II or its complex with AMPPNP, the nonhydrolyzable beta,gamma-imido analog of ATP, was carried out to probe the ATP analog-induced conformational change of the enzyme. Binding of the ATP analog is shown to convert the enzyme to a circular clamp with an annulet, through which only a linear DNA can pass; subsequent circularization of the bound linear DNA forms a salt-stable catenane between the protein circular clamp and the DNA ring. Analysis of catenane formation between a small DNA ring originally bound to the topoisomerase and a large DNA ring subsequently added, under conditions such that the two do not exchange, supports a model in which a second DNA double-helix can enter the open jaws of a DNA-bound protein clamp, and the closure of the jaws upon ATP-binding traps the second duplex and transports it through an enzyme-operated gate in the first DNA duplex.

Adenosine Triphosphatases↗