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Biomedical subjects

M Santos

Publications and source records attributed to M Santos.

At least 127 records · Page 7Linked to original sources
PubMed1996

Cardiopulmonary and analgesic effects of xylazine, detomidine, medetomidine, and the antagonist atipamezole in isoflurane-anesthetized swine.

The cardiovascular and respiratory effects of three alpha(2)-adrenergic agonists (xylazine 2mg/kg of body weight; detomidine, 40 micrograms/kg; medetomidine, 40 micrograms/kg) and their specific antagonist, atipamezole (200 micrograms/kg) were examined in young, isoflurane-anesthetized (1.3% end-tidal concentration) swine (weight range, 15 to 35 kg). The intravenous administration of all three alpha(2)-agonists caused an initial significant (P < 0.05) but short-lived increase in arterial blood pressure. Atipamezole also increased blood pressure, and this effect persisted throughout the period of observation. All agonists caused a sustained significant bradycardia, whereas atipamezole significantly increased heart rate (30 +/- 7 beats per min). The cardiac index tended to transiently decrease 5 to 10 min after agonist injection (significant only for xylazine at 2 min after injection) from an average pre-injection value of 166 ml/kg per min and did not change in response to atipamezole. None of the drugs significantly modified arterial blood gas (PaO2, PaCO2) or pH values. Xylazine and medetomidine but not detomidine or atipamezole manifested short-lived analgesic properties in response to clamping of the interdigital fold.

Adrenergic alpha-Agonists↗
PubMed1996

[Cardiorespiratory and analgesic effects of continuous infusion of propofol in swine as experimental animals].

HYPOTHESIS AND OBJECTIVES: To study the effects of 3 doses of continuous infusion of propofol on heart rate (HR), arterial pressure (AP), cardiac output (CO), pulmonary artery pressure (PAP), pulmonary capillary pressure (PCP), central venous pressure, flow volume, minute volume, arterial gases and analgesic effect. MATERIAL AND METHODS: Eighteen Landrace-Large-White pigs were randomly assigned to 3 groups of 6 based on dose of propofol used. An intravenous dose of 2 mg/kg propofol was followed by the continuous infusion corresponding to each group: group I (GI) received 9 mg/kg/h, group II (GII) received 11 mg/kg/h and group III (GIII) received 13 mg/kg/h, each for a period of 1 hour. Variables were recorded 5, 15, 30, 45 and 60 min after the intravenous induction dose. When the infusion was withdrawn, the time elapsing before recovery of sternal decubitus (SDT) position was recorded for each animal. RESULTS: The following changes from baseline values were statistically significant: AP and PAP increased and PaO2 and MV decreased in GI, with SDT recovery after 27 +/- 4 min; PA increased and FV decreased in GII, while SDT recovery was at 29 +/- 5 min; and diastolic arterial pressure, PCP, CO and HR decreased in GIII. All the pigs in the last group experienced apnea requiring mechanical ventilation and SDT was recovered after 63 +/- 7 min. PCP was significantly higher in GII and GIII than in GI. None of the doses produced an analgesic effect.

Analgesia↗
PubMed1996

Morphometric evidence of the regulation of the activity of LH-immunoreactive cells by corticosterone. An in vivo and in vitro study.

The present study was performed to investigate the morphometric effects of the administration of corticosterone on LH-immunoreactive cells of pituitary monolayer cultures. In addition, the effect of bilateral adrenalectomy on the LH-adenohypophyseal cells was explored. In vitro administration of corticosterone induced a marked decrease in the morphometric parameters considered (cellular, cytoplasmic and nuclear areas). In vivo, bilateral adrenalectomy produced a significant increase in these parameters when compared to those obtained in normal and sham-operated animals. However, when the bilaterally adrenalectomized rats received a daily dose of corticosterone no significant changes in the morphometric parameters were found. Morphometrically, these combined in vivo-in vitro findings confirm a corticosterone-induced hypoactivity of LH-cells together with a direct effect of this glucocorticoid on LH-adenohypophyseal cells.

Adrenalectomy↗
PubMed1995

Expression of a dominant negative mutant of epidermal growth factor receptor in the epidermis of transgenic mice elicits striking alterations in hair follicle development and skin structure.

Epidermal growth factor receptor (EGFR) is a key regulator of keratinocyte biology. However, the physiological role of EGFR in vivo has not been well established. To analyze the role of EGFR in skin, we have generated transgenic mice expressing an EGFR dominant negative mutant in the basal layer of epidermis and outer root sheath of hair follicles. Mice expressing the mutant receptor display short and waved pelage hair and curly whiskers during the first weeks of age, but subsequently pelage and vibrissa hairs become progressively sparser and atrophic. Eventually, most mice present severe alopecia. Histological examination of the skin of transgenic mice shows striking alterations in the development of hair follicles, which fail to enter into catagen stage. These alterations eventually lead to necrosis and disappearance of the follicles, accompanied by strong infiltration of the skin with inflammatory elements. The interfollicular epidermis of these mice shows marked hyperplasia, expression of hyperproliferation-associated keratin K6 and increased 5-bromo-2-deoxyuridine incorporation. EGFR function was inhibited in transgenic skin keratinocytes, since in vivo and in vitro autophosphorylation of EGFR was almost completely abolished on EGF stimulation. These results implicate EGFR in the control of hair cycle progression, and provide new information about its role in epidermal growth and differentiation.

Animals↗
PubMed1995

Previous aspirin use may attenuate the severity of the manifestation of acute ischemic syndromes.

BACKGROUND: The present study was designed to investigate whether the prior use of aspirin could influence the severity of the manifestation of acute coronary artery syndromes, given the well-documented observations that aspirin can prevent myocardial infarction, stroke, and death in cardiovascular disease. METHODS AND RESULTS: A series of 539 consecutive patients admitted to the Coronary Care Unit of a General Hospital was carefully characterized in a study with an ambidirectional design, with regard to previous medical history, aspirin use, and subsequent hospital diagnosis. Among the 214 patients previously taking aspirin, the hospital diagnosis was myocardial infarction in 24% and unstable angina in 76% compared with 54% and 46%, respectively, among the 325 not taking aspirin (P < .0001), for a reduction in the odds ratio of myocardial infarction with aspirin of 72% (95% CI, 59% to 90%). The decrease in odds was homogeneous in all subsets studied and independent of age, sex, previous angina, or previous myocardial infarction. The myocardial infarction was of a Q-wave type in 62% of aspirin users compared with 76% of nonusers (P < .05). By multivariate analysis, previous aspirin use was a strong predictor of unstable angina versus myocardial infarction and the only independent predictor of non-Q-wave versus Q-wave myocardial infarction. CONCLUSIONS: This study, thus, suggests a shift to less severe manifestation of acute coronary syndromes with aspirin use, implying that the failure of the drug in many patients with an acute coronary syndrome is only partial and that aspirin has the potential of attenuating the severity of the underlying acute thrombotic disease process.

Angina, Unstable↗
PubMed1995

Calbindin D-28k and parvalbumin expression in mitotic cells of rat primary cortical cultures.

Calbindin D-28k and parvalbumin expression was studied immunocytochemically in monolayer mixed cortical cultures from rats aged 16 (E16), 17 (E17), and 19 (E19) days of gestation using monoclonal antibodies and the avidin-biotin immunoperoxidase method. Whereas in vivo both calcium-binding proteins are exclusively expressed in postmitotic neuronal populations, they were demonstrated in mitotic cultured cells at the three fetal ages and the three maturation times considered (6, 12, and 15 days). A subpopulation of immunostained mitotic cells was identified as astroglial cells after a double labelling study using an antibody against glial fibrillary acidic protein. These results suggest that conditions in vitro may induce the expression of calbindin D-28 and parvalbumin in mitotic cells.

Animals↗
PubMed1995

Adrenalectomy increases the glial fibrillary acidic immunoreactive-elements in the ventricular ependyma and adjacent neuropil of the rat third ventricle.

The reactions of bilateral adrenalectomy (14 days) on the rat glial fibrillary acidic-immunoreactive elements of the third ventricular ependyma and adjacent neuropil were analyzed using histological, immunohistochemical and morphometric methods. Bilateral adrenalectomy led to a drastic increase in the number of immunoreactive elements located in the neuropil adjacent to the third ventricle and the optic chiasm when compared to normal and sham-operated animals (p < 0.05). By contrast, the adrenalectomized animals receiving corticosterone showed the same characteristics and morphometric values as those found in normal and sham-operated animals. The results show that the participation of the adrenal gland in astroglial responses should be taken into account.

Adrenalectomy↗
PubMed1995

The evolutionary history of Drosophila buzzatii. XXXII. Linkage disequilibrium between allozymes and chromosome inversions in two colonizing populations.

Chromosome polymorphism in Drosophila buzzatii is under selection but the genes responsible for the effect of the inversions of fitness are unknown. On the other hand, there is evidence for selection on several allozyme loci but the presence of paracentric inversions on the second chromosome, where most of the polymorphic loci are located, complicates the interpretation. Studies of the associations between allozymes and inversions are thus necessary to help understand the effect of selection at both the chromosomal and allozymic level. Until now this kind of information has only been available in D. buzzatii for two loci, Est-1 and Est-2, in Australian populations. Here we describe the genetic constitution of two Old World populations, Carboneras and Colera. Emphasis has been placed on the analysis of the linkage disequilibria between the second chromosome arrangements and three allozyme loci, Est-2, Pept-2 and Aldox, located on this chromosome. In addition, the recombination frequencies between the loci, and between the loci and the inversion breakpoints, have been estimated and a genetic map of the three loci has been produced. The two populations differ in allele and arrangement frequencies, as well as in the pattern of one-locus disequilibria. Est-2 and Aldox are associated with the second chromosome arrangements in both populations. On the other hand, Pept-2 is associated with the inversions in Colera but not in Carboneras. The gametic associations among the three loci are discussed taking into account the position of these loci on the chromosome map and the lack of recombination in the heterokaryotypes.

Animals↗
PubMed1995

Intraoperative radiation therapy in malignant glioma: early clinical results.

Intraoperative radiation therapy (IORT) with high energy electron beams is a treatment modality that has been included in multimodal programs in oncology to improve local tumor control. From August 1991 to December 1993, 17 patients with primary (8) or recurrent (9) high grade malignant gliomas, anaplastic astrocytoma (4), anaplastic oligodendroglioma (6) and glioblastoma multiforme (7), underwent surgical resection and a single dose of 10-20 Gy intraoperative radiation therapy was delivered in tumor bed. Fourteen patients received either pre-operative (8) or post-operative (6) external beam radiation therapy. Primary gliomas: 18-months actuarial survival rate has been 56% (range: 1-21+ months) and the median survival time has not yet been achieved. Four patients developed tumor progression (median time to tumor progression: 9 months). Recurrent gliomas: 18-months actuarial survival rate and median survival time has been 47% and 13 months (range: 6-32+ months) respectively. The median time to tumor progression was 11 months. No IORT related mortality has been observed. IORT is an attractive, tolerable and feasible treatment modality as antitumoral intensification procedure in high grade malignant gliomas.

Adolescent↗
PubMed1995

Heritability and selection on body size in a natural population of Drosophila buzzatii.

An attempt was made to assess whether the phenotypic differences in body size (as measured by wing length) between wild-caught mating and single Drosophila buzzatii males could be attributed to genetic differences between the samples. Mating males were found to be larger and less variable than a random sample of the population. The progeny of the mating males (produced by crossing to a random female from a stock derived from the same population) were on average larger than those of the single males, but not significantly so (P = 0.063), and less phenotypically variable. This difference in variance between the samples suggests that there are indeed genetic differences between the paternal samples but tests for significant differences in the additive genetic component of variance proved inconclusive. For both samples it was found that while the ratio of additive genetic variation in the laboratory to phenotypic variation in the field yielded estimates of ĥs2(N) congruent to 10% the regression of offspring reared in the laboratory on parents from the wild was not significantly different from zero. In addition, it was found that the average development time of the progeny of the mating males is shorter than that of the random sample.

Analysis of Variance↗
PubMed1995

Design and development of a utilization review program in Portugal.

This paper describes the work that has been under way in the Portuguese government hospital sector, with respect to the use of an adapted version of the Appropriateness Evaluation Protocol (AEP). Modifications to the original system were determined through a series of experiments at pilot hospitals and reliability and user profile studies were subsequently conducted using the modified criteria. Results were of great value in terms of the identification and quantification of problems. On average, approximately one in every four non-obstetric admissions and one in every 2 days of stay were deemed inappropriate and 75% of all inappropriate days were related to patients who were ready for discharge. It is expected that the use of the modified AEP will be extended and enhanced over the next few years. In this regard, advantage has already been taken of the implementation of an output-based funding system, combining retrospective statistical analysis of the hospitals' inpatient databases with targeted reviews of individual patients.

Health Services Research↗
PubMed1995

In vitro morphometric and proliferative variations in VIP-immunoreactive pituitary cells induced by estradiol.

Using double labelling for proliferating cell nuclear antigen (PCNA) and vasoactive intestinal peptide (VIP), a study was conducted to elucidate the repercussions of the addition of estradiol to monolayer pituitary cultures on the morphology, size, number, mitotic index and PCNA labelling index of VIP-immunoreactive cells, comparing the results with those obtained in control cultures. The addition of estradiol (100 nM) over 3 h of incubation led to a significant increase (p < 0.01) in the cellular, cytoplasmic and nuclear areas of VIP-immunoreactive cells and in the number of these cells. The same treatment elicited an even greater increase in the mitotic index (p < 0.01) and PCNA labelling index (p < 0.01) of VIP-immunoreactive cells. The results obtained suggest that estrogens induce proliferation and hyperplasia of in vitro VIP-immunoreactive pituitary cells.

Animals↗
PubMed1994

In vitro modulation of T-cell surface molecules by iron.

Iron and zinc are known to have immunomodulatory functions. In the present work, iron (FeC6H5O7) and zinc (ZnCl2) were tested in comparison to nickel (NiCl2) and cobalt (CoCl2) for their effect on six different surface molecules known to be involved in recognition and activation processes, namely CD4, CD2, CD3, CD8, HLA-ABC, and HLA-DR. Iron was seen to down-modulate expression of the CD4 and the CD2 molecules on the surface of T-lymphocytes, as indicated by a decrease in the mean fluorescence intensity measured by FACS analysis. None of the other T-cell molecules tested were significantly affected. In addition, the iron-mediated CD4 down-modulation reached its lowest level by 12 hr, at which time a striking decrease in the percentage of CD4+, but not CD8+, cells was observed. This decrease was followed by a gradual recovery starting at 18 hr and reaching its highest level at 48 hr. When cells were treated with other metal salts, none of those effects were observed. The present results suggest that iron may play a regulatory role in processes of T-cell recognition and T-cell activation by selectively down-modulating T-cell molecules known to be involved in these processes.

CD4 Antigens↗