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Biomedical subjects

F Guerrero

Publications and source records attributed to F Guerrero.

At least 37 records · Page 2Linked to original sources
PubMed2000

Clinical parameters (body mass index and age) are the best predictors for the need of insulin therapy during the first 18 months of diabetes mellitus in young adult patients.

To address the question whether there are simple clinical predictors of need for insulin in the first 18 months of treatment of diabetes presenting in young adult subjects, a prospective study of 24 patients with diabetes mellitus (age: 18-40 years) was designed. At diagnosis of diabetes, age, sex, body mass index (BMI), glycemia, ketonuria, C-peptide, insulin autoantibodies, islet cell antibodies and glutamic acid decarboxylase antibodies were recorded before starting any treatment. At the end of the follow-up (18 +/- 4 months), they were divided into two groups according to their need for insulin therapy: group 1 (n=15; 62%), who needed insulin therapy, and group 2 (n=9; 38%), who did not. Each marker was related to actual need for therapy necessity. Multivariate analysis showed that BMI and age were the variables with greatest predictive value regarding need for insulin. These data reveal that the need for insulin therapy in young adult diabetic patients may be supported by the clinical criteria of age and BMI, which are both easily and quickly determined.

Adolescent↗
PubMed2000

Improvement in the efficiency of oxidative phosphorylation in the freshwater eel acclimated to 10.1 MPa hydrostatic pressure.

Previous studies have suggested that the efficiency of oxidative phosphorylation in the freshwater eel (Anguilla anguilla) is increased after acclimation to high hydrostatic pressure. Analysis at atmospheric pressure of the respiratory chain complexes showed that, after 21 days at 10.1 MPa, the activity of complex II was decreased to approximately 50 % (P<0.01) of the control value and that cytochrome c oxidase (complex IV) activity was significantly increased to 149 % of the control value (P<0.05). ADP/O ratios calculated from mitochondrial respiration measurements were significantly increased after acclimation to high hydrostatic pressure (2.87 versus 2.52, P<0.001) when measured in the presence of pyruvate plus malate at atmospheric pressure. These results clearly show an increased oxidative phosphorylation efficiency in response to high-pressure acclimation.

Adaptation, Physiological↗
PubMed2000

Consistent production of a higher TH1:TH2 cytokine ratio by stimulated T cells in men compared with women.

OBJECTIVE: To evaluate the T helper 1 (T(H)1)/T helper 2 (T(H)2) lymphocyte cytokine profiles in women and men and to study the in vitro effects of sex hormones on lymphocyte secretion of cytokines. METHODS: Analysis of serum concentration and lymphocyte synthesis of T(H)1 (gamma interferon (INF-gamma) and interleukin 2 (IL-2)) and T(H)2 (interleukin 4 (IL-4) and interleukin 10 (IL-10)) cytokines was performed in 20 women and 15 men. Analysis of modifications in cytokine secretion induced by supplementation of lymphocyte culture with increasing concentrations of sex hormones was carried out. RESULTS: Higher levels of INF-gamma and IL-2 and lower levels of IL-4 and IL-10 were detected in the phytohemagglutinin-stimulated lymphocyte culture supernatants of men compared with women; the INF-gamma:IL-4 ratio was significantly higher in men. In women, similar concentrations of all the cytokines were detected in culture supernatants obtained during the follicular and the luteal phases. The addition of sex hormones did not modify the concentration of cytokines in supernatants of phytohemagglutinin-stimulated T-cell cultures. CONCLUSIONS: Women present a predominant T(H)2 cytokine profile, which could be involved in immune responses characterized principally by the secretion of antibodies. This could be a factor implicated in the higher concentration of immunoglobulins or the increased prevalence of autoimmune diseases detected in females.

Adult↗
PubMed2000

In vitro reactivity of ventral aorta to acetylcholine and noradrenaline in yellow freshwater eel (Anguilla anguilla L.) acclimatized to 10.1 MPa hydrostatic pressure.

We examined in vitro vascular reactivity of eels previously acclimatized to 10.1 MPa hydrostatic pressure (HP) for 21 days. The isometric tension developed by ventral aortic rings was measured at atmospheric pressure. Dose-response curves for either acetylcholine (ACh) or noradrenaline (NA), as well as contractions evoked by 80 mM K+, were compared with time-matched experiments conducted on rings obtained from control eels. Results showed that neither the optimal tension nor the maximal force of the K+-evoked contraction were significantly modified, suggesting that acclimatization to high HP did not change the vascular smooth muscle contractile machinery. The dose-response curve to ACh was not significantly changed. Conversely, although NA always relaxed aortic rings, the response of acclimatized eels was significantly reduced over the entire range of the agonist concentration tested (10(-8) to 10(-3) M), except for the lowest one (10(-9) M). The maximal amplitude of the NA-induced relaxation was significantly reduced in aortic rings from acclimatized eels as compared with non-acclimatized samples (339.3 +/- 86.5 vs. 744.3 +/- 72.1 mg x mg(-1) dry weight, P < 0.005). Our results suggest that acclimatization to high HP could selectively alter the control of vascular tone by catecholamines.

Acclimatization↗
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↗