Uncomplicated general anesthesia in the elderly results in cognitive decline: does cognitive decline predict morbidity and mortality?

Elderly surgical patients constitute a unique surgical group. They require special consideration in order to preempt the long term adverse effects of anesthesia. This paper examines the proposition that general anesthesia causes harm to elderly patients with its impact being felt long after the anesthetic agents are cleared from the body. One complication, Postoperative Cognitive Decline (POCD), is associated with the administration of anesthesia and deep sedation. Its' occurrence may herald an increase in morbidity and mortality. Based on both human and animal data, this paper outlines a unitary theoretical framework to explain these phenomena. If this hypothesis proves to be correct, anesthesiologist should consider regional rather than general anesthesia for equivalent surgical procedures to reduce POCD and consequently achieving superior patient outcome.

Pharmacological characterization and autoradiographic distribution of alpha2-adrenoceptor antagonist [3H]RX 821002 binding sites in the chicken brain.

Knowledge about the noradrenergic system in birds is very scarce even though their biological diversity and complex social behavior make them an excellent model for studying neuronal functions and developmental biology. While the role of norepinephrine has been described in depth in a large number of central and peripheral functions in mammals, reports for avian species are limited. The radioligand [(3)H]RX 821002 ([(3)H]1,4-[6,7(n)3H]-benzodioxan-2-methoxy-2-yl)-2-imidazol) has been used to map and characterize alpha(2)-adrenoceptors through the chicken brain using in vitro autoradiography and membrane homogenates binding assays. [(3)H]RX 821002 showed a saturable and high affinity binding to a site compatible with alpha(2)-adrenoceptor, and to a serotonergic component. The autoradiographic assays displayed a similar alpha(2)-adrenoceptor distribution than those previously reported in birds using other radioligands such as [(3)H]UK 14304 ([(3)H]5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine) or [(3)H]clonidine. [(3)H]RX 821002 binding pharmacological characterization was carried out in different chicken brain regions using membrane homogenates for competition assays with different alpha(2)-adrenoceptor agonists and antagonists drugs (oxymetazoline, BRL 44408 [2-(2H-(1-methyl-1,3-dihydroisoindole)methyl)-4,5-dihydroimidazole] ARC 239 [2-(2-4-(O-methoxyphenyl)-piperazin-1-yl)-ethyl-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione], prazosin, UK 14304 and RX 821002). The results showed alpha(2A) as the predominant alpha(2)-adrenoceptor subtype in the chicken brain while alpha(2B)- and/or alpha(2C)-adrenoceptor subtypes were detected only in the telencephalon. RX 821002, serotonin (5-HT) and 8-OH-DPAT [8-hydroxy-2-(di-n-propylamino)tetralin] competition assays, and competition binding assays performed in the presence of serotonin demonstrated that [(3)H]RX 821002 binds with higher affinity to a serotonergic component, probably 5-HT(1A) receptors, than to the alpha(2)-adrenoceptors. Similar pharmacological properties for the alpha(2)-adrenoceptor component were observed both in rat and chicken brain. The results demonstrate that the different alpha(2)-adrenoceptor subtypes are present in chicken brain and suggest that these receptors are highly conserved through evolution.

Cannabinoid system in the budgerigar brain.

Cannabinoid receptor density and cannabinoid receptor-mediated G protein stimulation were studied by autoradiographic techniques throughout the budgerigar (Melopsittacus undulatus) brain. The maximal CB(1) receptor density value (using [(3)H]CP55,940 as radioligand) was found in the molecular layer of the cerebellum (Mol), and high binding values were observed in the nucleus taeniae amygdalae (TnA), nucleus preopticus medialis, and nucleus pretectalis. The highest net-stimulated [(35)S]GTPgammaS binding values induced by the selective CB(1) receptor agonist WIN55,212-2 were observed in the nucleus paramedianus internus thalami, and high values of [(35)S]GTPgammaS binding were observed in the TnA, Mol, arcopallium dorsale and arcopallium intermedium. The distribution data suggest that in the budgerigar, as previously indicated in mammals, cannabinoid receptors may be related to the control of several brain functions in the motor system, memory, visual system, and reproductive behavior. The discrepancies between the cannabinoid receptor densities and the cannabinoid receptor-mediated stimulation found in several budgerigar brain nuclei support the hypothesis, previously described for mammals, of the existence of different G(i/o) protein populations able to associate with the cannabinoid receptors, depending on the brain structure, and could reflect the relative importance that cannabinoid transmission could exerts in each cerebral area.

Distribution of the gamma-aminobutyric acid(A) receptor complex alpha 5 subunit in chick brain. An immunocytochemical and autoradiographic study.

This work reports the distribution of the gamma-aminobutyric acid(A) (GABA(A)) receptor complex alpha5 subunit in the chick using an antibody raised against this subunit in the rat, an immunoprecipitation study and a comparative autoradiographic study using [(3)H]flunitrazepam in the presence of 1 microM zolpidem, which is considered to bind only to those areas presenting the alpha5 subunit. The specificity of the antibody for the chick GABA(A) receptor complex alpha5 subunit is supported by the similar bands obtained by Western blotting from rat and chick, the immunoprecipitation study and the general agreement in the distribution and pattern of labelling of this antibody in both species. The immunocytochemical and autoradiographic distributions in both the chick and rat are compared and some areas with disagreement between these distributions are discussed. The general conclusion is that the alpha5 subunit of the GABA(A) complex receptor seems to have been conserved along evolution.

Seizure-refractory period after a single stimulation and inhibition of seizures after repetitive stimulation in the gerbil: effects on blood cortisol levels.

PURPOSE: To determine the epileptic response of gerbils to external shock stimulus, assessing blood cortisol levels as a parameter to determine stress conditions. METHODS: Five sets of two-month-old Mongolian gerbils were stimulated to elicit seizures by the clapping of a sheaf of papers. Stimulation was done once a week over a 10-week period to obtain a stable situation and a similar response in all the animals. Four of the sets were killed to collect blood samples: those not manipulated; those stimulated twice a day for 5 days; those stimulated once to obtain samples immediately after seizure recovery; and those stimulated once to obtain samples 30 min after seizure recovery. Blood samples from the fifth set of animals were taken in vivo from the retro-orbital plexus. RESULTS: Eliciting seizures with this stimulus, twice a day in a repetitive way, prevented further induced seizures from the second day of stimulation on. Changes in the gerbils' behavior--from exploratory to escape mode--were also observed. The blood cortisol levels found in the sets of animals killed without induced seizures were similar to the others, regardless of whether the animals had been subjected to repetitive stimulation. Additionally, significant decreases in blood cortisol levels were detected in the animals killed immediately and 30 min after recovering from an induced epileptic episode. CONCLUSIONS: The normal refractory period in gerbils can be estimated at 1 h. The lack of correlation between cortisol levels and the inhibition of seizure-elicitation through repetitive stimulation supports the environmental and exploratory hypothesis of seizure generation rather than a stress hypothesis.

An organizational model for a primary care program of home health care in Spain: a description of the program.

The National Institute of Health (INSALUD) in Spain has successfully used a model of home care that has two major components, each using the physician as part of the team that provides care at home. The first component is home health care that is provided to chronically ill, terminally ill and homebound patients, whereby professionals of primary care provide care for the patient at home, along with other professionals who provide specialized care as support elements. The second component is hospitalization at home, whereby care is provided to acutely ill patients or patients with a precocious medical or surgical discharge from the hospital. The professionals from the hospital provide the basis of care. and the primary health care professionals are the support elements. Both components incorporate a team of support.