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Biomedical subjects

F Guerrero

Publications and source records attributed to F Guerrero.

At least 19 recordsLinked to original sources
PubMed1998

A scanning and immunohistochemical study in bovine haemal node.

The bovine haemal nodes are lymphatic organs with haemal circulation. The blood circulates inside of them through virtual cavities named sinuses. In these sinuses there is passage of cells and particulate materials from parenchyma to sinuses and vice versa. For this passage temporal overtures exist in the sinus walls. The sinus wall is composed of endothelial cells, basal membrane and reticular cells. Our results have demonstrated that type IV collagen was one of the basal membrane constituents in bovine haemal nodes and by this constitution a dynamic equilibrium of the sinus walls was permitted.

Animals↗
PubMed1997

Effect of Depo-Provera or Microgynon on the painful crises of sickle cell anemia patients.

Forty-three homozygous (SS) female sickle cell anemic patients with a history of at least one painful crisis per month and desiring a reversible contraceptive were administered DMPA/3 months or Microgynon monthly. A third group of 16 surgically sterilized patients served as control. Patients were followed for 1 year to assess possible effects of the contraceptives on the patients' painful crises. No changes were observed in any of the groups in the hematological parameters. At the end of the study, 70% of the patients receiving DMPA were pain-free and only 16% of those still reporting painful crises rated them as intense. Patients receiving Microgynon also had an amelioration of the painful crises, although at a lower rate; after 12 months, 45.5% still experienced some crises. Although less marked than in the other groups, 50.5% of the control patients also reported an improvement of their painful crisis, which may be a result of closer medical care.

Adolescent↗
PubMed1997

Hyperbaric-induced enhancement of noradrenaline-evoked contraction in rat thoracic aorta.

The aim of this study was to investigate the effects of a high ambient pressure of He on vascular contraction induced by noradrenaline and to distinguish the effects of ambient pressure per se from those of increased pressure of inert gas. Rings of thoracic aorta were isolated from male Wistar rats. Isometric tension was measured in preparations exposed to 7.1 MPa (absolute pressure) of He. Dose-response curves for noradrenaline and contractions elicited by 120 mM KCl were compared with time-matched experiments performed at atmospheric pressure. The same protocol was also carried out under 7.1 MPa of N2. At the high pressure of He, the contraction elicited by noradrenaline was increased with no change in the response to K(+)-evoked depolarization. The tension developed in response to noradrenaline also increased under 7.1 MPa of N2 but the effects were less marked than during the He experiments. Moreover, the response to KCl was reduced in this circumstance. Hyperbaric conditions enhance the noradrenaline-induced contraction of rat aorta in vitro. This effect probably results from an action of pressure per se on activation of adrenoceptors. However, the hyperbaric-induced increase in vascular smooth muscle contraction is partially counteracted by high pressures of inert gases (N2, but also probably He), which impair the efficiency of the contractile machinery.

Adrenergic alpha-Agonists↗
PubMed1996

Central inhibitory effect of adenosine deaminase on carotid blood flow increase at high pressure.

Carotid blood flow in rats was measured by implanted transit-time ultrasonic flowprobes throughout hyperbaric experiments conducted up to 70 bar (7 MPa) with a helium-oxygen hyperoxic (PO2 = 400 mbar) mixture. Before the hyperbaric experiment, an intracerebroventricular (ICV) injection of phosphate saline-buffered solution (PBS) or adenosine deaminase (ADA, 100 U.ml-1) in PBS was performed. Throughout the hyperbaric experiment carotid blood flow increased with ambiant pressure in PBS-treated rats. Conversely, the increase in carotid blood flow was attenuated by ADA treatment. These results suggest that the increase in carotid blood flow at high ambiant pressure could result from an increase of adenosine concentration in the rat brain.

Adenosine↗
PubMed1996

Changes of the basement membrane and type IV collagen in human skin during aging.

OBJECTIVES: To determine the relationship between skin collagen IV and basement membrane changes during aging, a total of 35 women who had been admitted for surgery, were studied. METHODS: Subjects were arranged into six age-groups (from 35 to 60 years). Skin biopsies were performed in all patients and the samples were taken from a site 6 cm above the pubic symphysis. The collagen IV content and the epithelial basement membrane were analyzed by using immunohistochemical, transmission electron microscopy and computer-assisted image analysis methods. The skin collagen IV content was measured by an image analysis program and expressed in arbitrary units of integrate optical density, and, the basement membrane thickness was expressed in nanometers. RESULTS: Type IV collagen content decreased with age after 35 years (r = -0.9561). The epithelial basement membrane thickness increased significantly with age (r = 0.98192; P < 0.01) and there is an inverse correlation between these two parameters (r = -0.990502). CONCLUSIONS: Although type IV collagen is a basement membrane component and declines with aging, the total thickness of this membrane increases, which suggests a reduction in tissue turnover.

Adult↗
PubMed1995

Effects of intracerebroventricular administration of aminophylline on hyperbaric-induced increase in carotid blood flow.

Carotid blood flow was measured in rats by implanted transit-time ultrasonic flowprobes during hyperbaric experiments at up to 70 bar (7 MPa) using an helium-oxygen hyperoxic (partial pressure of O2 = 400 mbar) mixture. Before the hyperbaric experiment, an intracerebroventricular injection of phosphate saline buffered solution (PBS) or aminophylline, an adenosine receptor blocker, in PBS was given. Throughout the hyperbaric experiment carotid blood flow increased with ambient pressure in both PBS, i.e. control, and aminophylline treated rats. The increase in carotid blood flow was significantly attenuated in aminophylline treated rats. Additional experiments showed that the increased carotid blood flow was independent of hyperoxia as well as of temperature. The hypothesis that the hyperbaric dependent increase in carotid blood flow was mediated by brain adenosine receptors and its implication regarding a cerebral vasodilatation are discussed.

Altitude↗
PubMed1995

Experimental Aujeszky's disease in blue foxes (Alopex lagopus).

Blue foxes were inoculated orally with Aujeszky's disease virus. Several foxes were killed at the onset of clinical signs and other animals spontaneously died. The incubation period ranged from 3 to 6 days and was followed by a short illness characterized by anorexia, depression and coma. At autopsy, no specific gross findings were observed. Microscopically, lesions included a non-suppurative meningoencephalitis with neuronal necrosis, gliosis, neuronophagia and mononuclear cell cuffing. Viral antigen was detected by immunoperoxidase technique.

Animals↗
PubMed1995

Effects of compression rate on rats carotid blood flow.

The effects of compression rate on carotid blood flow were investigated in awake rats submitted to hyperbaric experiments conducted up to 70 bar (7 MPa, gauge pressure) with either slow compression (0.1 bar/min), i.e., inducing only mild High Pressure Neurological Syndrome (HPNS), or fast compression (2 bar/min), i.e., in the earlier time course of experiments leading to epileptic seizures. Implanted transit-time ultrasonic flowprobes were used, and data were analyzed by regression methods. Mean carotid blood flow increased with ambient pressure during either low or high compression rate, but the increase was significantly more important with the latter. These results evidenced that carotid blood flow increased with ambient pressure, and moreover that this enhancement depends on compression rate.

Animals↗
PubMed1994

[The psychological factors that affect the making of a decision for surgical sterilization and the likely later changes].

The practice of female surgical sterilization in Panama during the past decades, motivated the realization of this study, to determine the factors which caused women to use this permanent contraceptive method, and to see if regrets later occurred after that decision, in the sterilized women. A sample of 151 women were selected, between the ages of 28 and 45 years, concurrently pregnant and with 2 or more living children at the moment of the study. Psychological tests were applied during three different phases (pre-operatively and subsequently 12 and 24 months, post operatively). Results showed that female sterilization did not cause long term complications, and amongst the majority of women conforming the sample, a stable psychological profile was found up to 24 months after the interventions, with a significant improvement in the last evaluation of the social adaptation variable, in comparison to the pre-operative assessment.

Adult↗
PubMed1994

[The history of family planning among women who opt for surgical sterilization in the Social Security Fund of Panama].

In this study, the previous history of family planning and prior usage of contraceptive methods are analyzed, in a sample of 175 women who voluntarily opted for surgical sterilization as a permanent method of fertility regulation, in the Panamanian Social Security System. A questionnaire was applied during the second trimester of pregnancy, by which information would be gathered in regard to knowledge, usage and adverse effects of the contraceptive methods used prior to the intervention. Results showed that 99% of the sample had heard, on some occasion about oral contraceptives (OC) and, in lesser proportion to intrauterine devices (IUD), barrier methods and hormonal inyectables. The first contraceptive method used, and the one of longest usage, was the combined OC, of which 43% begun between 17 and 25 years of age. In contrast, 7.4% initiated contraception with IUD, from the age of 26 years. The health personnel constituted the major source of recommendation for contraceptive usage and, despite the fact that 37% of the sample did not use contraception prior to the last pregnancy, over half of the subjects responded that combined OC were considered as the most secure method.

Adult↗
PubMed1992

Lipid and hormonal profile of Panamanian women during the menstrual cycle.

Forty-one women of reproductive age were included in the study, to establish the variation of serum lipids during the menstrual cycle and simultaneously, to determine the physiological fluctuation of FSH, LH, prolactin (PRL), progesterone (P4) and estradiol (E2) concentration in serum, during the menstrual cycle. A significant decrease of total serum cholesterol (165.29 +/- 3.6 mg/dl) and triglycerides (108.99 +/- 9.65) occurred during the luteal phase, as compared with the follicular phase (176.16 +/- 3.51, 108.99 +/- 9.65). Changes were not observed with HDL-cholesterol during the cycle. On the other hand, FSH showed an initial rise (mean 5 IU/l) followed by a surge (10 IU/l) and a progressive fall toward the midcycle. In contrast LH secretion showed a steady increase with a maximal concentration at surge (32.1 IU/l). PRL mean value was observed, with a discrete increase after day 13 of the menstrual cycle, that was more noticeable at the end of the cycle. Forty-eight hours after the FSH and LH midcycle surge, elevation of progesterone was observed, with maximal concentration occurring on day 24 (23 nmol/l) and later on progesterone levels fell rapidly. Thirty-six to 24 h before the surge of LH and FSH at midcycle was observed the peak serum concentration of estradiol (1300 pmol/l) followed by a progressive fall. Changes in the concentration of serum lipids during the menstrual cycle are presumably due to a direct or indirect effect of physiological fluctuation of sex hormones.

Adolescent↗
PubMed1992

T wave changes in humans and dogs during experimental dives.

Electrocardiogram (ECG) analysis was performed in three human divers studied at 21 and 23.5 ATA while they breathed various gas mixtures containing H2 and/or He (COMEX HYDRA IX experiment) and in five dogs exposed to 91 ATA of He-O2 or He-N2-O2. In all cases, the O2 partial pressure was slightly higher than its physiological value. These human and animal studies reveal that elevated pressure of different inert gases did not change the resting heart rate or its respiratory fluctuation. However, the T wave amplitude increased in proportion to the gas density in the three divers; this was also found in four of the five dogs studied. Changes in peak T wave configurations were also observed in the dog experiments. Positional changes in QRS or T vectors cannot explain these T wave changes.

Animals↗
PubMed1987

GNRH induces activation of Leydig-like cells in Pleurodeles waltlii. A morphometric study.

The ultrastructure of the interstitial cells of the glandular tissue of Pleurodeles waltlii was studied in testis of animals obtained in early breeding season (January) under gonadotropic releasing hormone (GNRH) treatments and controls. These cells (parenchymal or Leydig-like cells) displayed the structural characteristics of steroid-producing cells. GNRH administration for 24 hours induced a significant decrease of both medial volume and volume density of lipid droplets. On the other hand, cell volume, nucleus, mitochondria, mitochondrial cristae and tubules of smooth endoplasmic reticulum were increased. The surface density of mitochondrial cristae was also increased.

Animals↗
PubMed1986

Human cellular immune response to copolymer I and myelin basic protein.

Copolymer I (Cop I) is being tested as a treatment for MS because it protects animals against experimental allergic encephalomyelitis, and because there is immunologic cross-reactivity reported between Cop I and myelin basic protein (MBP). From the peripheral blood mononuclear cells of four normal individuals, we isolated helper-phenotype T-cell lines that reacted in vitro with Cop I or MBP. Cop I-reactive cell lines did not respond to MBP, nor did MBP-reactive T-cell lines respond to Cop I. Antigen-specific immune tolerance was induced in MBP-reactive cell lines by exposure to MBP in vitro, but similar exposure to Cop I did not induce tolerance in the MBP-reactive cell lines. We found no evidence of immunologic cross-reactivity between Cop I and MBP.

Animals↗
PubMed1985

Circulating T-cell subsets in Guillain-Barré syndrome.

We compared the distribution of circulating T-cell subsets within 2 weeks of onset of symptoms in 14 patients with acute Guillain-Barré syndrome (GBS) and 37 normal controls. The levels of OKT4+ (putative helper-inducer) cells was definitely abnormal (decreased) in 3/13 tested. The levels of OKT8+ (putative suppressor-cytotoxic) cells were elevated in 3 and decreased in 2 of the 14 tested. Abnormal OKT4/OKT8 ratios were detected in 5 (2 elevated and 3 decreased) patients. Four of the 5 GBS patients with abnormal OKT4+/OKT8+ ratios were studied sequentially at least 4 times over 1-10 months; there was a return towards a normal ratio in all. Serial studies in 3 other GBS patients showed consistently normal values. In comparison, sequential studies over 5-24 months in 7 normals showed no abnormal OKT4+/OKT8+ ratios. Thus, abnormalities in OKT4+/OKT8+ ratios appear to be a marker of systemic events during symptomatic phases of GBS. It is not as yet known whether this is related to the cause or is secondary to the clinical manifestations of GBS.

Antibodies, Monoclonal↗