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Biomedical subjects

J Diaz

Publications and source records attributed to J Diaz.

At least 199 records · Page 11Linked to original sources
PubMed1986

Ontogenetic changes in vasopressin binding site distribution in rat brain: an autoradiographic study.

Binding sites for [3H]vasopressin were identified in brains of neonatal (days 0-23) and adult (90 day) Long-Evans and Brattleboro rats, using a technique of in vitro receptor autoradiography. Results indicate that the regional distribution of binding sites for [3H]vasopressin in the brain changes markedly during postnatal development. Binding sites in the septum proliferated slowly to attain adult distribution in the dorsal and lateral septum, while in other regions, such as the caudate, hippocampus and cingulate gyrus, intense labeling appeared early in development but disappeared by adulthood. In the amygdala, binding did not change during postnatal development. Binding sites in the septum appeared before vasopressinergic fibers are present. Also, binding was present for vasopressin in regions which have not yet been reported to receive vasopressinergic innervation. Therefore, it is proposed that the presence of binding sites for vasopressin is independent of the presence of vasopressin itself. This hypothesis is supported by labeling in the Brattleboro rat which was comparable to that in the Long-Evans.

Amygdala↗
PubMed1986

Pepstatin analogues as novel renin inhibitors.

Pepstatin analogues corresponding to the general formula A-X-Y-Sta-Ala-Sta-R were synthesized in solution phase. Various changes in the nature of the A, X, and Y groups were made to improve the inhibitory potency against human plasma renin activity. The results were interpreted by use of the active-site model based on the sequence of human angiotensinogen. The tert-butyloxycarbonyl group and the isovaleryl group were found to be the most effective acyl groups (A). The analogues having a Phe residue in place of Val1 (X) and His or amino acid with an aliphatic side chain such as norleucine or norvaline in the Y position showed the highest inhibition of human plasma renin activity with IC50 values of about 10(-8)M. Esterification or amidification of the carboxyl group of the C-terminal statine did not change the inhibitory potency. The selectivity for rat, dog, pig, and monkey plasma renin of the most interesting compounds was studied.

Binding Sites↗
PubMed1986

Bronchodilator effect of the association ipratropium bromide plus fenoterol (low doses) versus terbutaline and salbutamol in bronchitic patients.

In 12 chronic bronchitic out-patients, during 3 successive days, the variations of FEV1 and Vmax25 were studied at 15, 30, 45, 60, 120, and 180 min after inhalation of: [0.1 mg fenoterol (F) associated with 0.04 mg ipratropium bromide (IB)]; [0.2 mg salbutamol (S)], and [0.5 mg terbutaline (T)]. There were no secondary effects resulting from any treatment. Maximum effectiveness appeared on FEV1 at 60 min with F + IB, and at 45 min with S and T. On Vmax25, it was produced after 30 min with F + IB and no modifications in this parameter were observed either with S or with T. After 15 min, there were changes on FEV1 with the three products: P less than 0.001 for F + IB and S; p less than 0.01 for T. The variation persisted for up to 120 min with F + IB (p less than 0.001) and with S (p less than 0.05), and for up to 60 min with T (p less than 0.01). With F + IB, Vmax25 increased since after 15 min (p less than 0.001) and up to 60 min (p less than 0.01). In conclusion, the association of a small dose of F to IB provides as positive results as S, and better than T, in a group of chronic bronchitic out-patients.

Adult↗
PubMed1986

[Economic losses from hoof diseases in cows].

Investigations were carried out under productional conditions with a total of 100 high-producing cows in lactation to disclose the effect of diseased hooves or hooves that had not been taken care of over the period in the stable as well as the effect of hoof trimming and treatment on the daily and monthly milk yield and the total losses associated with deformations and diseases in 20,980 cows. It was found that 'stable' hooves and disease processes developing in them and in the body as a whole lowered the milk yield by 3.3 l, on an average, per cow (4.5 l, respectively). Trimming of hooves and medical treatment were found to avoid the drop of the daily milk yield along with the recovering all losses and coming back to normal levels. Opportunely used treatment prevented the losses associated with live weight, lowered the percent of premature culling and emergency slaughter and reduced or fully ruled out the death cases. Economic losses could be kept to a minimum if the efforts described above ate coupled with periodic hoof trimming (at least twice a month).

Animals↗
PubMed1985

Resistance to metocurine-induced neuromuscular blockade in patients receiving phenytoin.

Recent reports have described resistance to pancuronium-induced neuromuscular blockade in patients chronically receiving anticonvulsants. This study examines the pharmacokinetics and pharmacodynamics of metocurine (MTC) in 12 patients undergoing craniotomy--six on chronic phenytoin therapy and six comparable controls. Each patient received MTC 0.2 mg/kg during the induction of general anesthesia. Quantification of plasma MTC concentration was performed by radioimmunoassay, while the response to MTC was evaluated by evoked compound electromyography (ECEMG). Patients in the phenytoin group were resistant to this dosage of MTC, as demonstrated by their response (83 +/- 16% compared with 98 +/- 2% depression of ECEMG in control patients, P less than 0.05) and by recovery index, defined as the time required for recovery from 25 to 75% of the control ECEMG (53 +/- 22 min compared with 125 +/- 54 min in control patients, P less than 0.01). Similarly, the total duration of neuromuscular blockade, measured to recovery to 90% of control ECEMG, was significantly shorter in the phenytoin group (122 +/- 25 min compared with 269 +/- 64 min in the control group, P less than 0.01). Plasma concentration-time curves were fit to biexponential equations for both groups. These were used to generate two-compartment models. Neither the model parameters nor the plasma concentrations of MTC at any time in the study were significantly different for the two groups. The pharmacodynamic analysis, however, showed that patients on phenytoin require a higher plasma concentration of MTC (0.415 +/- 0.095 microgram/ml compared with 0.249 +/- 0.066 microgram/ml in control patients at 50% ECEMG, P less than 0.01) to effect a given level of neuromuscular blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Pharmacokinetics and pharmacodynamics of d-tubocurarine and metocurine in the elderly.

The effects of age (older than 70 yr) on the pharmacokinetics and pharmacodynamics of d-tubocurarine (dTc) and metocurine (MTc) were evaluated in studies of 21 patients aged 70-87 and 21 patients aged 29-59. There was a significant difference in the pharmacokinetic parameters of all elderly patients compared with younger controls. With both dTc and MTc, the elderly exhibited a decreased plasma clearance, decreased initial volume of distribution, decreased volume of distribution, and a prolonged elimination half-life. After 0.3 mg/kg of dTc, the times for 50% return of twitch and recovery index (25-75% return of twitch response) in the elderly were significantly longer than in the young (P less than 0.02). A similar observation was made for the elderly patients receiving 0.15 mg/kg of MTc. No significant difference was seen in the log plasma concentration-twitch response relationship between 20-80% paralysis in young and in elderly patients receiving dTc. There was a similar lack of significant difference between the log plasma concentration-twitch response lines for elderly and young patients receiving MTc. Because there was no difference between the plasma concentration-response relationships in the elderly and young, altered sensitivity to dTc or MTc cannot explain the longer duration of action seen in the elderly. The most likely explanation for this difference is the altered pharmacokinetics of these two drugs in the elderly.

Adult↗
PubMed1984

Intrauterine contraception with copper and with levonorgestrel: a randomized study of the TCu 380Ag and levonorgestrel 20 mcg/day devices.

First year results of a randomized study of 1509 users of the Copper T380Ag with a silver core or of an IUD releasing 20 mcg day of levonorgestrel are reported. The cumulative gross pregnancy rate for each device was 0.3 per 100 at one year, with more than 490 women having one year of use with each device. The levonorgestrel-releasing device was associated with significantly fewer bleeding days and significantly increased hemoglobin levels when compared with pre-admission values or the one year values observed among users of the TCu380Ag. Terminations attributable to amenorrhea were significantly more frequent among users of the levonorgestrel-releasing device. The TCu 380Ag was associated with increased frequency and severity of dysmenorrhea compared with pre-admission levels or with the steroid-releasing device. Hemoglobin levels were somewhat reduced among users of the TCu 380Ag device. Terminations attributable to pain were, however, not significantly different by device. Continuation rates at the end of the first year were not significantly different by device.

Adolescent↗
PubMed1984

Distribution, elimination, and action of d-tubocurarine in neonates, infants, children, and adults.

The relation of plasma concentration of d-tubocurarine (dTc) to neuromuscular blockade, and the distribution and urinary excretion of dTc was determined in neonates (n = 4), infants (n = 6), children (n = 8), and adults (n = 8). The plasma concentration-time course curves to 24 hr are best described for all groups by three-compartment models. Both neonates and infants exhibit decreased plasma clearance (CLP), 1.1 +/- 0.08 and 1.0 +/- 0.06 ml X kg-1 X min-1, and in addition a prolonged t1/2 terminal phase, 311 +/- 44 and 306 +/- 35 (mean +/- SEM, min). The neonates' 24-hr urinary excretion, 27 +/- 2 (mean +/- SEM, % total dose) is significantly less than the adult value, 45 +/- 4% total dose. There was no significant difference seen in the log plasma concentration-evoked compound electromyogram (ECEMG) response between 20-80% paralysis for adults, children, infants, and five of the seven neonates studied. Two of the neonates had a significant shift of their log concentration-response curve to the right. There was also no significant difference between any of the groups in the time for 50% return of ECEMG stimulus height or the time required for recovery of the ECEMG from 25 to 75% of control value. for recovery of the ECEMG from 25 to 75% of control value.

Adult↗
PubMed1984

Chemiluminescence from an erythrocyte folic acid oxidase from normal individuals and from cancer patients.

Folic acid oxidase from erythrocytes oxidatively cleaves folic acid at the C-9-N-10 bond to yield pterin-6-aldehyde and p-aminobenzoyl glutamic acid, with the concomitant generation of singlet oxygen. The emission from singlet oxygen is proportional to the enzyme activity. DABCO was used as a singlet oxygen emission enhancer to increase the sensitivity of the measurement. In general, pregnant women show high enzymatic activity, but the emission is strongly quenched by DABCO. This is contrary to normal and cancer cases in which an increase in the emission was observed. This effect is larger in cancer cases. These results are presented as a potential method for detecting physiological and pathological human conditions.

Erythrocytes↗
PubMed1983

A microwave-hyperthermia model of febrile convulsions.

While convulsions associated with fever represent a serious problem in pediatric medicine, conventional animal models of febrile convulsions suffer numerous technical limitations. A microwave-hyperthermia model that eliminates these problems was tested. Microwave energy was used to increase the core temperature of 13- and 17-day-old rats, resulting in convulsions similar to febrile convulsions in human infants. Rats were irradiated for 10 min in circularly polarized waveguides at 918 MHz, CW (average SAR = 9.4 W/kg at 13 days and 18.0 W/kg at 17 days as determined by twin-well calorimetry). Day 17 irradiated rats were less susceptible to convulsions that were day 13 irradiated rats, indicating an age-dependent decline in susceptibility. Contrary to findings of earlier models using infrared or hot-oven heating, convulsions induced with microwave hyperthermia impaired neither brain growth nor subsequent performance during behavioral testing. Simultaneous measurement of brain and rectal temperatures during microwave irradiation revealed differential heating rates that favor thermal homeostasis in brain tissue.

Animals↗
PubMed1983

Disruption of the brain growth spurt in adolescent rats by chronic phenobarbital administration.

Postweanling rats received daily injections of either 60 mg/kg phenobarbital, 15 mg/kg phenobarbital, or the drug vehicle from their postnatal days 25 through 39. Even though there were no differences among the groups in body weight, the group receiving 50 mg/kg phenobarbital had significantly smaller whole brain weights and larger liver weights than the other groups. These data suggest that, (i) brain growth may be vulnerable to disruption even in its late stages and (ii) barbiturates may constitute a threat to normal brain growth.

Animals↗
PubMed1983

Somatic and central nervous system growth in artificially reared rat pups.

Rearing preweanling rat pups away from their mothers by feeding through chronic intragastric cannulas has been shown to result in alterations in the growth of specific organs. In the present study, artificially reared (AR) rats and their normally reared (NR) siblings were sacrificed at various ages during this procedure to determine the time course of these alterations. Brain growth deficits were detected within 24 hours, peaked after 8 days of artificial rearing and showed some recovery by the end of the study. By day 18, the livers, kidneys and spleens of the AR pups were significantly larger than those of their NR siblings. The spleens showed an initial decrease in weight compared to the spleens of the NR pups. However, by day 18, the spleens of the AR group were significantly larger than those of the NR group.

Age Factors↗
PubMed1983

Two years' experience with two levonorgestrel-releasing intrauterine devices and one copper-releasing intrauterine device: a randomized comparative performance study.

A randomized comparative performance study of two levonorgestrel intrauterine devices (IUDs) and a copper (Nova-T) IUD (Leiras, Turku, Finland) was performed at two clinics in Finland and one in Brazil. The 24-month cumulative event rates per 100 women are reported. Six thousand woman-months of use were recorded with the levonorgestrel IUD and 3000 with the Nova-T device. Pregnancy rates at 2 years of use were 0.6 and 0 with the two levonorgestrel IUDs and 3.3 with the Nova-T IUD. Removal rates because of bleeding and/or pain were low with all three IUDs: 7.5, 7.6, and 7.1, respectively, at 24 months. Recordings of the number of days of bleeding showed significantly fewer days of bleeding during use of the levonorgestrel IUDs than the Nova-T IUD from the second month of use onward, until the end of the second year. No infections were recorded in association with use of the levonorgestrel IUDs, and only one termination because of infection was recorded for the Nova-T IUD. The continuation rates of use at 24 months were 66.6, 60.7, and 71.9 for the two levonorgestrel IUDs and the Nova-T IUD, respectively; the differences were not statistically significant.

Adolescent↗
PubMed1982

Clinical performance of a new levonorgestrel-releasing intrauterine device. A randomized comparison with a nova-T-copper device.

The clinical performance of two levonorgestrel-releasing intrauterine devices (IUDs) with different release rates was studied and compared with a copper-releasing Nova-T device in a randomized partly double-blind multiclinical trial. Special attention was given to patterns of bleeding, hormonal side-effects, blood pressure and body weight. The clinical acceptability of the levonorgestrel IUDs was as good as that of the copper-releasing IUD. A highly significant decrease in the amount of menstrual blood loss was seen with the levonorgestrel-IUDs, the users of which experienced fewer days of bleeding than prior to insertion. Patients suffering from dysmenorrhea experienced relief from this symptom after insertion of a levonorgestrel-IUD. Some side-effects, usually referred to as hormonal, increased during the levonorgestrel-IUD use, but did not result in higher termination rates than with the Nova-T device. No changes in body weight were recorded for the levonorgestrel-IUDs and a slight decrease in both systolic and diastolic blood pressure was found after one year of use. No infections were recorded.

Adolescent↗
PubMed1982

Artificial rearing of rat pups with a protein-enriched formula.

Neonatal Long-Evans hooded rat pups were assigned to one of three groups: 1) pups normally reared, 2) pups implanted with intragastric cannulas and artificially reared with a common milk replacement formula, 3) pups implanted with intragastric cannulas and artificially reared with a protein-enriched milk formula. Daily body weights were recorded, as were the ontogeny of various reflexes. On day 18, the animals were behaviorally tested and then killed. There were no differences among the three groups in daily body weights, nor in the ontogeny of reflexive behavior. There were no differences in the wet weights of caudal brain sections, but the normally reared animals had significantly larger rostral brain sections than either artificially reared group. While cerebella of normally reared animals were significantly larger than those of the two artificially reared groups, there was a significant trend towards more normal cerebellar weights with the addition of protein in the formula of artificially reared animals. Behavioral tests indicated that the animals artificially reared have significantly different behavior than normally reared animals. However, compared to animals artificially reared using a common milk formula, animals artificially reared with additional protein in their formula behave more like normally reared animals.

Animals↗
PubMed1982

Infant gastrostomy and chronic formula infusion as a technique to overfeed and accelerate weight gain of neonatal rats.

Female rat pups were overfed by continuous intragastric infusion of a milk formula from day 4 through day 128 postpartum. These rats dramatically accelerated weight gain after day 109. By day 18 the overfed pups weighted significantly more than both normally reared 18-day-old pups and pups reared artificially but maintained at the same growth rate as normally reared pups. On day 18 the catheters were removed from gastrostomized pups and normally reared pups were removed from their dams. Thereafter, all groups were maintained ad libitum on a standard diet. The body weights of overfed pups were still significantly greater than those of both other groups on day 120. The procedure provides an important new tool to examine the role of early nutrition in the etiology of obesity.

Animals↗