Biomedical subjects

J Diaz

Publications and source records attributed to J Diaz.

At least 181 records · Page 10Linked to original sources

PubMed1989

Somatostatin inhibition of VIP-induced somatostatin release, cyclic AMP accumulation and 45Ca2+ uptake in diencephalic cells.

The effect of somatostatin (SRIF) on VIP induction of SRIF secretion, cyclic AMP accumulation and 45Ca2+ influx was investigated in cultured diencephalic cells. [D-Trp8]SRIF suppressed VIP-stimulated SRIF release and decreased VIP-stimulated cyclic AMP accumulation in a dose-dependent manner. SRIF-14 blocked basal and VIP-stimulated 45Ca2+ entry into cells. The data suggest that the inhibitory effect of SRIF on VIP-induced SRIF release is partly due to a decrease in Ca2+ entry into cells.

Animals↗

PubMed1989

Sprouting of frog motor nerve terminals after long-term paralysis by botulinum type A toxin.

A single sublethal injection of botulinum type A toxin (BoTx-A) to winter frogs induced a general and complete paralysis of skeletal muscles, which lasted several months. Quantitative analysis of 483 end-plates from 8 BoTx-A poisoned muscles and 495 endplates from 8 control muscles revealed a higher and significant incidence of terminal and ultraterminal sprouts in poisoned junctions when taking into account the normal remodelling of motor innervation. We conclude that prolonged neuromuscular blockade by BoTx-A results in the extension of the nerve terminal arborization.

Animals↗

PubMed1989

Terminal nerve sprouting at the frog neuromuscular junction induced by prolonged tetrodotoxin blockade of nerve conduction.

The effects of a prolonged blockade of nerve conduction by tetrodotoxin on frog motor innervation were studied in the cutaneous pectoris muscle of Rana esculenta. Prolonged nerve blockade (up to 22 days) was obtained by repeated subperineural injections of tetrodotoxin. Changes in morphological parameters of neuromuscular junctions were investigated in muscles after staining with a combined cholinesterase-silver method. In addition, changes in the incidence of polyneuronal innervation were investigated conjointly by electrophysiology and morphology. Morphometric analysis of singly innervated muscle fibres of 60 microns diameter revealed insignificant changes during the first week of tetrodotoxin-nerve blockade. After 15 days of paralysis, the mean length of synaptic contacts and the mean length of terminal arborization per synapse were significantly increased as compared to controls (contralateral muscles and citrate buffer-injected controls). After 20-22 days, differences in synaptic and aborization mean lengths were accentuated and reached 44 and 43%, respectively. At that time, the mean number of terminal branching points and of continuous synaptic contacts were also significantly increased (around 20 and 50%, respectively). No changes in the length of abandoned gutters were observed. The incidence of focal polyaxonal innervation (detected morphologically) and of polyneuronal innervation (determined electrophysiologically) was unchanged. The results show that prolonged tetrodotoxin blockade induces sprouting of the terminal arborization which results in an extension of pre-existing nerve terminals and an increase in the complexity of terminal arborization by addition of new branches. Nodal (collateral) sprouting was not changed.

Acetylcholinesterase↗

PubMed1989

Bacteriological study of choledochal bile in patients with common bile duct stones, with or without acute suppurative cholangitis.

Acute suppurative cholangitis is a serious complication in extrahepatic biliary tract obstruction. Bacteriological studies have shown that in these patients the bile cultures usually present several kinds of bacteria, especially Gram-negative aerobic bacteria such as E. coli and Klebsiella sp. The mortality rate in our patients with common bile duct stones and acute suppurative cholangitis is enhanced 5- to 10-fold. The aim of the present study was to analyse the bacterial properties of choledochal bile in a large number of patients with common bile duct stones, with or without acute suppurative cholangitis, and to determine the sensitivity of the isolated bacteria to several antibiotics used in clinical practice. The greatest sensitivity of the bacteria isolated from the common bile duct was seen for aminoglycosides (gentamicin and amikacin) and for cephalosporins, especially of the third generation (cefotaxime, ceftazidime, ceftriaxone and cefoperazone). Ampicillin showed a low sensitivity rate. The appropriate selection of the antibiotics used in acute suppurative cholangitis depends not only on the concentration of the antibiotic in the bile; a high plasma concentration is even more important to control the septic manifestations. A high excretion to the bile can affect the intestinal flora, leading to diarrhea (e. g. with cefoperazone). Ampicillin has been giving contradictory results in respect of bile and plasma concentrations. Gentamicin attains 30-40% of the plasma concentration in the bile, but persists for as long as 8 hours with excellent sensitivity and clinical efficacy. Amikacin reaches 44% of the plasma concentration with a very high sensitivity (96%).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1989

Penicillin allergy.

Explore the source record for details and available documents.

Drug Hypersensitivity↗

PubMed1988

Ontogeny of susceptibility to experimental febrile seizures in rats.

Two experiments were conducted using microwave hyperthermia (MHT) to induce seizures among limited numbers of Long-Evans rat pups. The MHT model of febrile seizures eliminates several methodological complications inherent in previous animal models of the disorder. In Experiment 1, rat pups were rendered hyperthermic with MHT or were sham-irradiated on Days 11, 13, 15 or 17 postpartum. The results indicate a statistically significant decline in seizure susceptibility with age. In Experiment 2, rats were subjected to either single or multiple hyperthermic episodes on Days 11, 13, 15, or 17 postpartum. The results indicate an increase in susceptibility to seizures attributable to prior seizure history. In both experiments, seizures were induced with increases in rectal temperature of 1 to 3 degrees C. The results parallel many clinical features of febrile seizures and argue the efficacy of the MHT model.

Animals↗

PubMed1988

Electrophysiological and morphological study of polyneuronal innervation in the cutaneous pectoris muscle of adult frog (Rana esculenta).

The incidence of polyneuronal innervation in the cutaneous pectoris muscle of the adult frog, Rana esculenta, was determined quantitatively using electrophysiological and morphological techniques. The mean percentages of multiple innervated endplates obtained with both techniques from a series of 19 muscles examined at all times of the year were in very good correlation: 30.7% (196/639 endplates) by electrophysiology and 30.5% (478/1569 endplates) by morphology. In nine muscles examined during the period from December to March the mean percentages, 36.8% (110/299) by electrophysiology and 38.6% (281/727) by morphology, were significantly higher than those obtained for 10 muscles investigated during the period from May to November, 25.3% (86/340) and 23.4% (197/842) with both techniques respectively. The higher incidence of collateral sprouted branches detected at polyinnervated endplate sites in muscles of winter frogs might be related to these seasonal variations. Most of the 1688 fibres from 26 muscles examined throughout the year exhibited one centrally located endplate. However, around 11% of them were found to be innervated at two separate endplate sites. Muscle fibres exhibiting this type of innervation were invariably the largest fibres in each muscle tested, having an apparent diameter greater than 48 micron. The distance between the endplates of these fibres represented between 10 and 30% of their total length. No significant seasonal variations were observed in the incidence of these dually innervated fibres. In conclusion, both electrophysiological and morphological results show that the normal incidence of polyneuronal innervation in the cutaneous pectoris muscle of adult Rana esculenta is affected by seasonal related factors which influence the nodal sprouting activity. Moreover, they show that a dual pattern of innervation is a common feature in large fibres of this muscle.

Animals↗

PubMed1988

Measurement of parathyrin in blood from thyroid veins: two radioimmunoassays compared in patients with primary hyperparathyroidism.

We measured parathyrin (PTH) in peripheral venous blood samples and in thyroid veins (both homolateral and contralateral to the lesion) in 13 patients with surgically confirmed parathyroid adenomas. Two different RIAs were used, one specific to the mid-region of the molecule (44-68, M-PTH), the other specific to the carboxy-terminal region (65-84, C-PTH). With the M-PTH assay we established a statistically significant multiple correlation (P less than 0.05) between the PTH concentrations in blood from the peripheral and thyroid veins; no significant correlation was found when we used the C-PTH assay. Our results confirm the superiority of the M-PTH RIA over the C-PTH RIA for study of hormonal secretion in primary hyperparathyroidism.

Adult↗

PubMed1987

Two years of intrauterine contraception with levonorgestrel and with copper: a randomized comparison of the TCu 380Ag and levonorgestrel 20 mcg/day devices.

IUDs releasing 20 mcg/day of levonorgestrel (LNg20) were in randomized trial together with the Copper T, model TCu 380Ag, in seven centers involving 2244 women. Two-year (25 months) gross cumulative pregnancy rates were 0.2 +/- 0.2 and 0.9 +/- 0.3 for the levonorgestrel and copper releasing devices, respectively (P greater than 0.05). There were no ectopic pregnancies in more than 1600 woman-years of use of each device. Removal rates for bleeding and/or pain or for medical reasons other than menstrual problems did not differ significantly between devices. Oligomenorrhea or amenorrhea prompted 10.7 per hundred (gross rate, 8.4 net rate) women using the LNg 20 IUD to request removal in the two-year period, significantly above the 0.2 per hundred rate among women with the Copper IUD (P less than 0.001). At the end of two years an estimated 59.4 per 100 women were continuing use of the LNg 20 IUD, and 67.5 per 100 (P less than 0.001) with the TCu 380Ag. This difference is almost wholly ascribable to a marked reduction in bleeding episodes and days among women using the LNg 20 device with concomitant removal of device. Hemoglobin rose an average of 0.5 g/dl (P less than 0.001) for this group whereas women using the TCu 380Ag experienced a decline of 0.2 g/dl compared with baseline values (P less than 0.001).

Adolescent↗

PubMed1987

Structural responsiveness of filamentous bacteriophage Pf1: comparison of virion structure in fibers and solution. The effect of temperature and ionic strength.

X-ray diffraction from fibers and magnetically oriented solutions has been used to study the effect of changes in environment on the helical symmetry and radial structure of the Pf1 virus particle. Detailed analysis of equatorial scattering to a spacing of 8-10 A was used to identify small radial motions of structural elements in the virus particle. R-factor ratios were used to determine the statistical significance of observed changes. Comparison of the structure of virus particles in fibers with those in solution indicated that the helical symmetry of the virions remains unchanged during fiber formation. In most fibers the virions appear to be slightly distorted by the tight packing of virus particles. This distortion results in an apparent increase in the radius of the virus particle of approximately 0.6 A. A change in the radius of the DNA is also observed. Increase in the concentration of solvent molecules during fiber formation results in penetration of the virus interior by some solvent components. NaCl is also able to enter the virus interior. The change in the helical symmetry of the virions at approximately 8 degrees C appears to be the same whether observed by diffraction from fibers or from solutions. Only subtle changes in radial structure are associated with the temperature transition.

Coliphages↗

PubMed1987

Results of in vitro fertilization attempts in women 40 years of age and older: the Norfolk experience.

Twenty-nine patients 40 years of age or older were stimulated with gonadotropins, starting on day 3 of the cycle, in a total of 64 cycles (January 1983 to June 1985) for multiple follicular development for in vitro fertilization. Most patients' infertility was due to tubal disease (n = 8) or pelvic endometriosis (n = 14). The mean number of preovulatory and immature oocytes recovered per laparoscopy was 2.53 +/- 1.73 and 1.57 +/- 1.58, respectively. There were no statistically significant differences between the number of preovulatory and immature oocytes harvested, fertilized, or transferred in this group and the number in patients younger than 40 years of age. No statistically significant differences were observed between peripheral estradiol and progesterone levels in patients 40 years of age or older and levels in patients 39 years of age or younger. There were 15 pregnancies in this group of patients, for a pregnancy rate of 23.4% per stimulated cycle, 27.7% per laparoscopy, and 29.4% per transfer. The ongoing pregnancy rate (12%) was lower, and the total abortion rate (60%) was higher, in patients 40 years of age or older in comparison with patients 39 years of age or younger. Patients 40 years of age or older should be counseled regarding the high abortion rate in this group.

Adult↗

PubMed1987

Characteristics of growth hormone response to the administration of growth hormone-releasing hormone (GRF) in the lamb.

Human growth hormone releasing hormone (GRF 1-44 or GRF 1-29) was administered to lambs at two different physiological stages (suckling: 5-6 week-old and weaned: 14-15 week-old) when growth hormone (GH) secretory patterns were different: suckling lambs exhibited flat basal GH profiles (5-10 ng/ml) while the weaned lambs had frequent spontaneous episodes of GH release (15-65 ng/ml). The iv injection of GRF evoked an immediate release of GH. In each case, plasma GH levels reached a maximum 1-4 min after the injection. The secretory spike was multiphasic and lasted 30-60 min. Administration of GRF (0.1 microgram/kg) in weaned lambs induced GH pulses with an amplitude comparable to that of endogenous peaks. The induction of a GH peak occurred even when a spontaneous peak immediately preceded the GRF injection. Also, spontaneous peaks were observed during the hour following a GRF-induced GH peak. In suckling lambs, GRF injected intravenously as a single bolus in a range of 0.01 to 0.5 microgram/kg (2 to 100 pmoles/kg) stimulated GH release in a dose-dependent manner. Chronic administration of GRF (0.75 nmole GRF 1-44 or GRF 1-29 per kg twice daily for 21 days) in newborn lambs increased significantly (p less than 0.001) the acute response to GRF during the course of the treatment. GH response to GRF 1-44 and GRF 1-29 was the same. These data show that lambs are highly responsive to GRF action during both suckling and weaning and suggest that there is no in vivo desensitization of the pituitary gland after acute or chronic GRF administration.

Animals↗

PubMed1987

Long-term effects on adiposity after preweaning nutritional manipulations in the gastrostomy-reared rat.

Male Long-Evans rat pups were either fed by continuous intragastric infusion of a milk formula to match the growth rate of their normally reared siblings, or overfed by continuous infusion of a fat-supplemented formula from d 4 through d 18 postpartum. The early overfeeding accelerated growth and the overfed rats remained significantly heavier than normally reared siblings as adults. Early overfeeding with this procedure led to an adult obesity at 14 mo characterized by significantly larger epididymal and retroperitoneal fat depots resulting from an increase of both fat cell size and number, and by an increase in adipose tissue lipoprotein lipase activity. Gastrostomy rearing per se, without overfeeding, resulted in adult rats that weighed the same as normally reared siblings but had significantly larger retroperitoneal fat depots because of more adipocytes. These findings suggest that the quantity of food consumed during early growth and development, and the quality of early nutrition and/or the early rearing environment affect adipose tissue development and have long-term consequences that persist in the rat.

Animal Nutritional Physiological Phenomena↗

PubMed1987

The effect of phenytoin on the magnitude and duration of neuromuscular block following atracurium or vecuronium.

Patients chronically receiving anticonvulsants have been reported to be resistant to the long-acting competitive neuromuscular blockers. This study examines the effects of atracurium and vecuronium on 100 neurosurgical patients; 50 receiving chronic phenytoin therapy (group I) and 50 controls (group II). During O2/N2O/halothane anesthesia, five patients in each group were given a bolus of vecuronium 0.1 mg/kg, and a different five patients in each group were given atracurium 0.5 mg/kg, to produce neuromuscular blockade in excess of 95%. The time to maximum blockade and the recovery from atracurium was unaffected by phenytoin therapy. Recovery from vecuronium was enhanced in the phenytoin group, as demonstrated by the recovery index, defined as the time required for recovery from 25-75% of the control neuromuscular response (7.9 +/- 2.2 min compared with 17.8 +/- 5.1 min in controls, P less than 0.005). Similarly, the total duration of neuromuscular blockade, defined as recovery to 90% of control response, was significantly shorter in the phenytoin group (31.9 +/- 6.0 min compared with 69.7 +/- 12.9 min in controls, P less than 0.001). The remaining 40 patients from each group were given a preselected dose of either vecuronium (0.02-0.06 mg/kg) or atracurium (0.10-0.25 mg/kg) during anesthesia with O2/N2O/fentanyl, to generate dose-response curves for the relaxants. Using analysis of covariance, the slopes and elevations for atracurium were found to be essentially identical in the two groups; as were the calculated ED50 and ED95. Patients receiving chronic phenytoin therapy were resistant to vecuronium-induced neuromuscular blockade. With vecuronium, the dose-response curves for the two groups were parallel; the curve for phenytoin patients was shifted to the right.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

An improved combined cholinesterase stain and silver impregnation method for quantitative analysis of innervation patterns in frog muscle.

The original method combining Karnovsky's cholinesterase stain and Bodian silver impregnation has been modified to stain both myelinated and unmyelinated axons and to reduce background staining. The improvements were obtained by adding nitric acid to a paraformaldehyde-acetone fixative and by carrying out the silver impregnation of axons in an alcoholic solution. The method is especially suitable for quantitative estimation of the different kinds of nerve sprouting as well as for study of the remodeling of neuromuscular junctions in normal and experimental frog muscles.

Animals↗

PubMed1987

Morphometry of nuclear rings at high electron microscopic resolution.

In studying the fine structure of the nuclear chromatin, a new organelle was discovered, the nuclear ring. In its isolated form, this structure is rather like a geometric torus: a smooth, structureless ring. This paper presents the results of electron microscopic morphologic measurements on 424 isolated rings, i.e., rings found free of any fibrous connections. From the measurements of inner and outer diameters, other geometric features were also calculated. Overall, the size of the rings varied about fivefold. Inner and outer diameters were closely correlated, suggesting a rather stable thickness of the ring itself. The significance of the nuclear ring is as yet poorly understood. With its occasionally intimate connections to both chromatin fibers and to the inside of the inner nuclear envelope, its role is likely to be a crucial one. The membrane covering its opening is none other than the bilayer of the nuclear envelope. The concept of a patent opening or "pore" does not appear tenable in the face of this and related findings.

Chromatin↗

PubMed1986

Preliminary experiment with computerized anamnesis in gynecology and reproductive health.

The Hospital of the Faculty of Medical Sciences of the State University of Campinas is implementing an Integrated Health Care Programme, whose objectives are early detection of risk factors of several diseases and the evaluation of the patient's reproductive health at the moment of the first visit to the Hospital. The initial results of this program encouraged us to try to apply it all to our own clientele. The present lack of material resources and qualified manpower leads us to concentrate all our attention on the patient's immediate complaints. This situation indicated to us that the only way to implement the program should be by means of a computerized questionnaire able to detect diseases and risk factors early. This paper presents the preliminary results of the application of computerized questionnaires to evaluate health risks. The authors conclude: The application of a computerized questionnaire met with very favorable reception by the clientele; In some segments of the population, the questionnaire can be answered by the patients in direct interaction with the computer; Programmes which evaluate risk factors need to be carefully revised before being put to use; The system operates on a relatively low cost basis, which could bring undeniable benefits to primary health care.

Computers↗

PubMed1986

Influence of taste stimulation during the suckling period on adult taste preference in rats.

Effects of taste deprivation and selective taste exposure during the suckling period on adult preference for flavored solutions was examined. Taste deprivation was achieved by rearing rat pups "artificially," in individual cups with intragastric feeding from Postnatal Days 4 through 17 or 18. In the first study the effects of artificial rearing on male Long-Evans rats were examined. In the second study female Wistar rats were exposed to a single tastant, sucrose, which was introduced on a background of taste deprivation. Results of both studies were similar. No differences in taste sensitivity or preference were detected between animals subjected to taste deprivation or selective taste exposure and their normally reared littermates. These results suggest that suckling stimulation is not necessary for normal taste development and that the taste system of the rat is not particularly susceptible to the influence of early experience. Other interpretations of these results are also discussed.

Animal Population Groups↗