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E Perez

Publications and source records attributed to E Perez.

At least 109 records · Page 6Linked to original sources
PubMed1987

Kinetic parameters of tyrosine hydroxylase in the rat's preoptic region during sleep deprivation and recovery induced by ambient temperature.

The role of catecholaminergic mechanisms in determining the changes in the rat's preoptic cyclic adenosine monophosphate (cAMP) concentration during sleep deprivation and recovery induced by ambient temperature was investigated in the present study. To this end, the activity of tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, was measured in the preoptic region of rats maintained in: (a) control (22 degrees C for 52 h), (b) deprivation (-10 degrees C for 52 h), and (c) recovery (22 degrees C for 4 h after 48 h at -10 degrees C) conditions. The enzyme followed a Michaelis-Menten kinetic. The analysis of substrate-related kinetic parameters (Km and Vmax) did not show any clear-cut difference between experimental conditions, which, as already known, induce both sleep deprivation and recovery in relation to significant cAMP changes.

Animals↗
PubMed1987

Chronic stimulation of ocular sympathetic fibers in unanesthetized rabbits.

The goal of this study was to devise a technique to implant permanent electrodes in the cervical sympathetic trunk, to stimulate the ocular adrenergic fibers for periods of hours or days in awake, unrestrained rabbits. Electrodes were made of a silver wire soldered to a multistranded wire and enclosed in silicone. Two of these electrodes were wrapped around the preganglionic sympathetic nerve, their leads emerging through a hole in the back of the neck. Success of the procedure was confirmed by the mydriasis elicited by electrical stimulation of the nerve following surgery; threshold voltages for the pupillary response varied between 5-10 volts. In eight rabbits, suprathreshold sympathetic stimulation was performed on the following days by means of a portable stimulator using increasing frequencies (1, 3, 5, 8, and 10 Hz) during a 20-hr period. Dilation of the ipsilateral pupil and vasoconstriction in the ear, measured by the fall in temperature of the ear's surface, was observed as long as stimulation was maintained. Both effects were proportional to the frequency of stimulation. Maximal mydriasis was obtained at 8 Hz, whereas full vasoconstriction was elicited with 5 Hz. Intraocular pressure, measured in 10 rabbits with a Perkins tonometer at the end of a 24-hr stimulation period, did not differ from pre-stimulation values. It was concluded that chronic stimulation of the sympathetic nerve allows to maintain known levels of adrenergic activity in the eye, and may be a useful method to study the actions of the adrenergic system on various ocular functions in unanesthetized animals.

Animals↗
PubMed1987

Effects of chronic sympathetic stimulation on corneal wound healing.

To explore the possibility that adrenergic fibers influence epithelial wound healing in the rabbit cornea, chronic electrodes were implanted in the left cervical sympathetic nerve, and symmetrical wounds were produced on the corneal epithelium of both eyes by means of n-heptanol. Continuous sympathetic stimulation was applied to awake, unrestrained animals during the wound-healing process (2-3 days) by use of a portable stimulator that delivered 1 ms, 3-Hz electric pulses at an amplitude necessary to evoke mydriasis. Migration rates of epithelial cells surrounding the wound and estimated wound closure times were calculated by measuring the reduction in wound size. In stimulated corneas, the epithelial migration rate was smaller (36.9 +/- 6.2 microns/hr) than in control corneas (49.4 +/- 5.4 microns/hr), the differences being significant (P < 0.05). Significant differences in wound closure times between stimulated (53.2 +/- 6.8 hr) and control (41.3 +/- 5.5 hr) corneas were also observed. These results suggest a modulatory influence of corneal adrenergic fibers on the processes that follow epithelial injury of the cornea.

Adrenergic Fibers↗
PubMed1986

Collagen at interfaces. I. In situ collagen adsorption at solution/air and solution/polymer interfaces.

Collagen was isolated from rat tail tendons and acetylated with 1-14C acetic anhydride. In situ adsorption of this collagen from a buffer solution (pH = 2.7) was measured at the interfaces to air, polyethylene and polyethylene grafted with poly(maleic acid), respectively. The kinetics of adsorption were recorded for all surfaces studied and the corresponding diffusion coefficients for collagen in solution with various protein concentrations were calculated. The desorption of collagen from polymer surfaces was also studied. These experiments reveal the existence of both a reversibly and an irreversibly adsorbed collagen layer on the polymers tested. The desorption/adsorption ratio for the polyethylene is higher than that for the grafted polyethylene indicating stronger interactions of collagen with the grafted surface than with the non-modified polyethylene.

Adsorption↗
PubMed1986

Monoclonal antibodies to bovine and human acrosin.

Monoclonal antibodies to human acrosin were required for studies of immunological interference with fertilization. Since human acrosin was not available in adequate amounts, monoclonal antibodies have been raised in mice against purified bovine acrosin and screened for cross-reaction with human sperm cells. Two of these antibodies are described, B4F6 and C2E5. Data from enzyme-linked immunosorbent assays, immunoblots, immunoprecipitation, and indirect immunofluorescence on sperm cells indicate that B4F6 binds only to bovine acrosin, and that C2E5 binds both to bovine and to human acrosin at a conformationally determined epitope. The antibodies do not inhibit the hydrolysis of benzoylarginine ethyl ester by acrosin, but C2E5 did inhibit the dissolution of the hamster zona pellucida by purified human acrosin. The antibodies have also been used for affinity purification of acrosin and proacrosin.

Acrosin↗
PubMed1986

[Intra-abdominal pseudotumorous panniculitis. CAT scan aspects of a case localized in the greater omentum].

Intra-abdominal panniculitis is an inflammatory and necrotic reaction to local, general or undetermined aggressions to intra- or retro-peritoneal fatty tissue. A case localized to the greater omentum is described and findings on CT scan imaging reported: encapsulated, heterogeneous mass of fatty density with fibrous bands and with fascial thickenings. Diagnosis is based mainly on histopathology, the CT scan being incapable, despite the clinical context, of formally rejecting a diagnosis of liposarcoma.

Adipose Tissue↗
PubMed1985

Compliance to referrals from the psychiatric emergency room.

Factors affecting compliance to referrals in the psychiatric emergency room (ER) were studied in a sample of 468 patients referred for ambulatory care. Compliance was defined as attendance at the first appointment. The overall compliance rate was 59%. Compliance rates were higher among those patients who were receiving psychiatric treatment (active) when they visited the ER. Those in treatment tended to have either Schizophrenic or Personality Disorders with fewer social supports. Different factors affected those in treatment and those not in treatment. The results suggest that those not in treatment would comply more frequently with specific instructions outlining the benefits of psychiatric follow-up.

Adult↗
PubMed1984

Hypothalamic temperature during desynchronized sleep.

The influence of changes in heat loss at specific heat exchangers, appraised by recording ear skin temperature (Ts), on the hypothalamic temperature (Thy) rise during desynchronized sleep (DS) was studied in unrestrained cats at different ambient temperatures (Ta). The correlations of initial and final Thy changes (delta iThy and delta fThy) with initial and final Ts changes (delta iTs and delta fTs), respectively, are statistically not significant. However, a significant negative correlation was found between delta fiThy, i.e. delta fThy-delta iThy, and delta fiTs, i.e. delta fTs-delta iTs. The latter result shows that only after its initial rise is Thy affected by changes in heat loss at specific heat exchangers during DS. Accordingly, delta fThy and delta fiThy are positively correlated with Ta. However, also delta iThy, although not affected by heat loss changes at specific heat exchangers, shows a positive correlation with Ta. On the basis of these results and of the data in the literature, it is concluded that three independent factors underlie Thy changes during DS, namely heat loss at specific heat exchangers, hypothalamic blood flow and thermogenesis.

Animals↗
PubMed1982

cAMP concentration in the rat's preoptic region and cerebral cortex during sleep deprivation and recovery induced by ambient temperature.

cAMP concentrations in the preoptic region and cerebral cortex were studied in rats during exposure to low ambient temperature (-10 degrees C) and after return to control ambient temperature (22 degrees C). Significant changes in cAMP concentration were found only in the preoptic region. On prolonged exposure to low ambient temperature the nucleotide concentration decreased and the circadian rhythm, observed in control conditions, disappeared. Return to control ambient temperature after exposure to low ambient temperature induced a steep increase and a long-lasting plateau in cAMP concentration. The results are discussed in terms of interaction between thermoregulatory and sleep-wakefulness processes.

Animals↗
PubMed1982

Consultation liaison training in Canadian psychiatric residency programs.

Canadian Psychiatry Residency programs were surveyed through questionnaires to determine the status of Consultation Liaison Training (CLT) for the year 1979/80. Virtually all the programs offered CLT as lecture/seminars and clinical postings. The majority of residents who received CLT were in their first and second years, with the average trainee spending less than 6% of total clinical training time in Consultation Liaison work. About 9% of the total core teaching time was devoted to Consultation liaison Psychiatry (CLP) and related topics. Canadian medical students are exposed to CLP in various forms during their training. There is little interdisciplinary collaboration or post-residency fellowships in CLP at this time. The authors suggest that CLT be offered in the last two years of training when the trainee can be an effective consultant with a consolidated identity as physician and psychiatrist. They also recommend an increase in inter-departmental collaboration and further development of post-residency fellowships in Consultation Liaison Psychiatry.

Canada↗
PubMed1980

Neuraminidase from influenza virus A (H3N2): specificity towards several substrates and procedure of activity determination.

Neuraminidase (acylneuraminyl hydrolase, EC 3.2.1.18) from the influenza virus A/Hong Kong/68 (H3N2) was purified after treatment of the purified virus with sarcosyl (sodium laurylsarcosinate), centrifugation at 110 000 x g, and chromatography on DEAE-Sephadex and Sephadex G-200. It migrated as a single component during electrophoresis on polyacrylamide gel, and its molecular weight was estimated about 270 000. The enzyme was thermolabile, the activity being reduced to 60% in 10 min at 50 degrees C. The purified neuraminidase had an apparent Km value of 4.1 . 10(-3) M for 5-N-acetyl-2-O-(3-methoxyphenyl)-alpha-D-neuraminic acid and was able to release sialic acid with linkages alpha 2-3, alpha 2-6 and alpha 2-8 (with very different efficiency) from fetuin, gangliosides, colominic acid, and bovine and porcine submaxillary mucins. The enzymic activity was measured by several procedures: (A) spectrophotometric determination at 340 nm of the NADH produced in the reaction catalysed by beta-galactose dehydrogenase on beta-galactose + NAD+, this beta-galactose was the product released from lactose by beta-galactosidase and lactose was the product of the neuraminidase activity on N-acetylneuraminyl-lactose; (B) determination of the colored quinone yielded by the liberated methoxyphenol with 4-aminoantipyrine (Santer, U.V., Yee-Foon, J. and Glick, M.C. (1978) Biochim. Biophys. Acta 523, 435-442); (C) periodate-thiobarbiturate procedures (Warren, L. (1959) J. Biol. Chem 234, 1971-1975 or Aminoff, D. (1961) Biochem. J. 81, 384-391). Some peculiarities of these methods are discussed.

Gangliosides↗
PubMed1980

Photoperiodic rhythm of cAMP concentration in the rat's preoptic region.

Photoperiodic influences on cAMP concentrations in the preoptic region and parietal cortex of the rat were studied at different ambient temperatures. In the preoptic region a photoperiodic rhythm is present at control Ta (22 degrees C) and is strongly attenuated at low Ta (-10 degrees C). In the parietal cortex no statistically significant photoperiodic changes were observed either at control or low T(a)s.

Animals↗
PubMed1980

[Changes in cyclic AMP concentration of the rat preoptic region as a result of long term exposure to cold].

The cAMP concentration in the preoptic region was studied in rats during exposure to low ambient temperature (Ta: -10 degrees C) and after return to control Ta (22 degrees C). With respect to control cAMP concentration, changes were observed consisting of a decrease (delta cAMP: 4.19 /+- 0.15 pM/mg Pr; p < 0.001) at low Ta and an increase (delta cAMP: 1.40 /+- 0.13 pM/mg Pr; P < 0.05) after return to control Ta. In contrast, cortical cAMP concentration decreased both at low Ta (delta cAMP: 2.94 /+- 0.09 pM/mg Pr; P < 0.005) and after return to control Ta (delta cAMP: 3.21 /+- 0.09 pM/mg Pr; P < 0.001). such cAMP changes in the preoptic region may be related to different activation levels of thermoregulatory and sleep mechanisms.

Animals↗