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Biomedical subjects

M A Mayer

Publications and source records attributed to M A Mayer.

15 recordsLinked to original sources
PubMed2006

Oral treatment and in vitro incubation with fructose modify vascular prostanoid production in the rat.

1.-- In the rat, a fructose-enriched diet induces hyperglycaemia, hypertriglyceridaemia, insulin resistance and hypertension; a model which resembles the human metabolic syndrome. 2.-- Prostanoids, metabolites of arachidonic acid, include vasoactive substances synthesized and released from the vascular wall that have been implicated in the increase of peripheral resistance, one of the mechanisms involved in the fructose-induced hypertension. 3.-- The aim of the present study was to: (i) analyse the effects of the in vitro incubation with fructose on the production and release of prostanoids in rat thoracic aorta and in rat mesenteric bed and (ii) compare the effects of incubation with those of the in vivo acute and chronic treatment of rats with fructose and with the combination of both in vivo and in vitro procedures. 4.-- Blood pressure, glycaemia and triglyceridaemia were significantly elevated in both 4- and 22-week fructose-treated groups. Meanwhile, body and heart weight as well as insulinaemia were similar between experimental animals and controls. 5.-- In aortae, 4 weeks of Fructose treatment did not modify the prostanoid pattern release, but in vitro incubation decreased prostacyclin (PGI(2)) production. However, after 22 weeks, fructose treatment and incubation exerted the same effect. 6.-- In mesenteric bed, after 4 weeks, the incubation and the combination of both procedures reduced the release of the vasodilators PGI(2) and PGE(2), while fructose treatment only diminished the PGE(2) release. On the contrary, the production of the vasoconstrictor thromboxane A(2) (TXA(2)) was enhanced by incubation and both the procedures. After 22 weeks, fructose treatment increased PGI(2) release, while it was reduced by incubation. The combination of both did not modify this peripheral resistance when compared with controls. Finally, incubation of tissues from treated rats increased the release of the vasoconstrictors, PGF(2alpha) and TXA(2). 7.-- In conclusion, the mesenteric bed, a resistance vascular bed, seems to be more sensitive than the aorta, a conductance vessel, to the effects of fructose on prostanoid production. This difference could be related to a more relevant role of resistance vessels in the regulation of peripheral resistance and consequently of blood pressure. The observed effects should contribute to a shift in the balance of the release of prostanoid in favour of vasoconstrictor metabolites. This phenomenon could be related to an increase in the peripheral resistance and the mild hypertension observed in the fructose-treated rats.

6-Ketoprostaglandin F1 alpha↗
PubMed2004

Fructose overload modifies vascular morphology and prostaglandin production in rats.

1. A fructose (Fru)-enriched diet induces a mild increase in blood pressure associated with hyperglycaemia, hypertriglyceridaemia, and insulin resistance, resembling the human 'syndrome X', being an useful model to study hypertension and type 2 diabetes. 2. A sustained elevation of blood pressure is associated with cardiovascular structural modifications such as left ventricular hypertrophy and increased wall thickness:lumen diameter ratio in blood vessels. 3. Prostanoids (PR), metabolites of arachidonic acid through the cyclooxygenase pathway, include vasoactive substances synthesized and released by the vessel walls. 4. The aim of the present study was to analyse, in Fru-treated rats: (i) the morphology of mesenteric vessels and; (ii) the PR production in aorta and mesenteric vessels, in order to assess whether these parameters are related with the haemodynamic alterations observed in this experimental model. 5. Blood pressure, glycaemia and triglyceridaemia, were significantly elevated in both (4 and 22 weeks) Fru-treated groups. Meanwhile body and heart weight as well as insulinaemia were similar between experimental animals and controls. 6. The mesenteric vessels of Fru-treated rats (22 weeks) showed an increased thickness and area of the media when compared with the controls; meanwhile, the lumen diameter was similar in both groups. 7. The Fru treatment for 4 weeks did not modify PR production in aorta, whereas in the mesenteric bed it diminished prostaglandin (PG) E(2) release significantly compared with the controls. However, in the group treated for 22 weeks, Fru reduced PGI(2) production in the aorta, as assessed by 6-keto-PGF(1)alpha measurements. Meanwhile, in the mesenteric bed, the chronic Fru treatment decreased PGE(2) release but, rather surprisingly, increased the output of PGI(2) when compared with its corresponding controls. 8. In conclusion, the present study shows the existence of an alteration in the morphology of mesenteric vessels in Fru-treated rats, which could be related to an increase in peripheral resistance and the consequent mild hypertension observed in this model. However, a diminished release of vasodilator PRs, such as PGE(2) in mesenteric vessels at 4 and 22 weeks and PGI(2) in aorta at 22 weeks could further impair the vessel response. The increase in PGI(2) observed in the chronic group in mesenteric vessels could be attributed to a compensatory mechanism.

Animals↗
PubMed2003

MedCIRCLE: collaboration for Internet rating, certification, labelling and evaluation of health information on the World-Wide-Web.

We describe MedCIRCLE, an EU-funded semantic web project to implement the first steps towards a global, collaborative rating and guidance system for health information proposed in the MedCERTAIN project. In MedCIRCLE, three European gateway sites for consumer health information will implement the metadata vocabulary HIDDEL (Health Information Disclosure, Description and Evaluation Language). HIDDEL allows portals and gateways to make the results of their evaluations accessible as XML/RDF. The three participating national portals are: AQUMED (Agency for Quality in Medicine) patienten-information, de, COMB (Official Medical College of Barcelona) and CISMeF, a quality-controlled health gateway developed at Rouen University Hospital. Other health subject gateways, accreditation, or rating services are invited to join the collaboration simply by implementing HIDDEL on their gateways. Widespread implementation HIDDEL will allow intelligent agents or client-side software to harvest statements and opinions about the trustworthiness of other websites, assisting users in selecting trustworthy websites. The MedCIRCLE project builds on, expands and continues work on rating health information on the Internet piloted within the MedCERTAIN project. While MedCERTAIN provided the core technologies and software for rating and "trustmarking" health information, MedCIRCLE is built around these technologies and involves a wider medical community to assess health information, demonstrating the power of collaborative and interoperable evaluations in a semantic web environment. MedCIRCLE is a project with the overall objective to develop and promote technologies able to guide consumers to trustworthy health information on the Internet, to establish a global web of trust for networked health information, and to empower consumers to positively select high quality health information on the web. Other aims include refinement and expansion of HIDDEL, to become a standard vocabulary and interchange format for self- and third-party ratings of health information.

Europe↗
PubMed1988

Analysis of information processing and cognitive disability theory.

This study used the information-processing approach to conceptualize planning and problem-solving abilities and to expand the theoretical and empirical data base of Claudia Allen's cognitive disability model. The congruent validity of the Allen Cognitive Levels (ACL) test as a measure of cognition, specifically of the fluid information-processing abilities that underlie learning, was investigated. Criterion measures used were subtests of the Wechsler Adult Intelligence Scale-Revised edition (WAIS-R). Forty adult psychiatric patients participated in the study. Spearman r coefficients showed moderately high correlations between the ACL test and the WAIS-R subtests measuring fluid abilities, and Performance scale IQ. These results indicate that Allen's model and test can be useful in guiding occupational therapy planning when expected outcomes depend on the patient's learning potential.

Adolescent↗
PubMedDate not supplied

Effects of alpha methyl-para-tyrosine on the recall of a passive avoidance response.

Treatment with alpha methyl-para-tyrosine 4 hr before training on a passive avoidance task altered recall in mice tested 24 hr after training. The observed alterations were dependent on the intensity of the footshock used during training. Retention of the avoidance habit was reduced by drug treatment when a footshock of 1.6 milliamperes (mA) was employed, while retention by drug-treated mice was enhanced when a footshock of 0.16 mA was used. No significant differences in retention were noted when a footshock of 0.8 mA or no footshock was employed. These results could not be explained on the basis of drug-induced changes in activity or sensitivity to footshock, of to state-dependent learning.

Animals↗