Zero balance ultrafiltration for the correction of acute acidosis after a period of prolonged deep hypothermic circulatory arrest

A 36-year-old woman with normal renal function underwent a total arch replacement requiring 110 minutes of deep hypothermic circulatory arrest. Prior to rewarming, a pH of 7.063 with a base deficit of 10.8 was obtained. Zero-balance ultrafiltration (Z-BUF) was initiated during rewarming 7 minutes after resumption of cardiopulmonary bypass. After one hour (10L) of Z-BUF, all electrolyte and acid-base disturbances were fully corrected. Our case illustrates that Z-BUF offers a valuable option for the correction of severe electrolyte and acid-base disturbances in adults undergoing cardiac surgery. Its use should be considered in addition to the more standard pharmacologic approaches to such derangements as it offers rapid and predictable electrolyte and acid-base correction and potential anti-inflammatory benefits.

Lack of genetic linkage or association between a functional serotonin transporter polymorphism and panic disorder

Given the efficacy of medications that interact with the serotonin transporter (5-HTT) in the treatment of panic disorder, we have used a family-based design to test for genetic association and linkage between panic disorder and a functional polymorphism in the promoter of the gene for 5-HTT. In this study, 340 individuals in 45 families, as well as 74 haplotype relative risk 'trios' were genotyped at the polymorphic locus, which consists of a 44 base pair deletion/insertion. There were no significant differences in allele frequencies or occurrence of genotypes within the triads. No linkage between the 5-HTT polymorphism and panic disorder was observed in the multiplex families, using a variety of simulations for dominant and recessive models of inheritance. Recent reports suggest an association between the 5-HTT polymorphism and anxiety-related traits, as measured with personality assessment. The results reported here provide evidence that the genetic basis of panic disorder may be distinct from anxiety-related traits assessed by personality inventories in normal populations.

Results of a genome-wide genetic screen for panic disorder

Panic disorder is characterized by spontaneous and recurrent panic attacks, often accompanied by agoraphobia. The results of family, twin, and segregation studies suggest a genetic role in the etiology of the illness. We have genotyped up to 23 families that have a high density of panic disorder with 540 microsatellite DNA markers in a first-pass genomic screen. The thirteen best families (ELOD > 6.0 under the dominant genetic model) have been genotyped with an ordered set of markers encompassing all the autosomes, at an average marker density of 11 cM. Over 110,000 genotypes have been generated on the whole set of families, and the data have been analyzed under both a dominant and a recessive model, and with the program SIBPAIR. No lod scores exceed 2.0 for either parametric model. Two markers give lod scores over 1.0 under the dominant model (chromosomes 1p and 20p), and four do under the recessive model (7p, 17p, 20q, and X/Y). One of these (20p) may be particularly promising. Analysis with SIBPAIR yielded P values equivalent to a lod score of 1.0 or greater (i.e., P < .016, one-sided, uncorrected for multiple tests) for 11 marker loci (2, 7p, 8p, 8q, 9p, 11q, 12q, 16p, 20p and 20q).

Inhibition of nitric oxide synthase blocks N-methyl-D-aspartate-, quisqualate-, kainate-, harmaline-, and pentylenetetrazole-dependent increases in cerebellar cyclic GMP in vivo

The synthesis of nitric oxide by brain slices has been demonstrated in several laboratories. In addition, in vitro studies have demonstrated stimulation of nitric oxide synthesis by excitatory amino acid receptor agonists. These data have led to the hypothesis that this readily diffusible "intercellular messenger molecule" acts to generate a cascade effect by activating guanylate cyclase in several cell types and thereby augment levels of the second messenger cyclic GMP (cGMP). Therefore, we evaluated this hypothesis in vivo, by testing the actions of the nitric oxide synthase inhibitor N-mono-methyl-L-arginine (NMMA) on elevations in level of mouse cerebellar cGMP generated by excitatory amino acid receptor agonists. The stimulatory effects of D-serine, quisqualate, and kainate were all found to be antagonized by this enzyme inhibitor. In addition, NMMA antagonized the increases in cerebellar cGMP level elicited by harmaline and pentylenetetrazole, pharmacological agents that augment endogenous excitatory amino acid transmission. Our data are, therefore, the first in vivo demonstration that nitric oxide is an important "messenger molecule" in the cerebellum, mediating the actions of kainate, quisqualate, and N-methyl-D-aspartate receptor agonists on guanylate cyclase. These data are consistent with previous in vitro findings with kainate and N-methyl-D-aspartate.

In vivo antagonism of agonist actions at N-methyl-D-aspartate and N-methyl-D-aspartate-associated glycine receptors in mouse cerebellum: studies of 1-hydroxy-3-aminopyrrolidone-2

Intracerebellar injections of either NMDA or D-serine dramatically elevated levels of cGMP in the cerebellum of the mouse, in vivo. These actions were both antagonized by simultaneous injection of the NMDA-associated glycine receptor antagonist, HA-966. Intracerebellar injections of D-serine were also antagonized by peripheral (s.c.) injections of HA-966, demonstrating the bioavailability of this glycine receptor antagonist. Parenteral administration of HA-966 was also effective in antagonizing the actions of intravenously injected harmaline, an activator of the cerebellar climbing fiber pathway, on cGMP in the cerebellum. An evaluation of the parenteral dose-response curve for HA-966, revealed no effect on basal activity within the cerebellum. This contrasts sharply with the abilities of both competitive and non-competitive NMDA antagonists to decrease basal levels of cGMP in the cerebellum. In summary, these studies demonstrate that HA-966 is a bioavailable antagonist of the NMDA-associated glycine receptor and that this compound can limit excessive stimulation of the NMDA receptor by exogenous application of agonist, with minimal effects on basal activity. These data suggest that antagonists of the NMDA-associated glycine receptor may be optimal therapies in the treatment of stroke and epilepsy.

BMY-14802 antagonizes harmaline- and D-serine-induced increases in mouse cerebellar cyclic GMP: neurochemical evidence for a sigma receptor-mediated functional modulation of responses mediated by the N-methyl-D-aspartate receptor complex in vivo

BMY-14802 [alpha-(4-flurophenyl)-4-(5-fluoro-pyramidinyl)-1-piperazine butanol], a potent sigma ligand with poor affinity for dopamine and phencyclidine receptors in vitro, attenuated parenteral harmaline- and direct intracerebellar D-serine-induced increases in mouse cerebellar cGMP. Intracerebroventricularly injected BMY-14802 also antagonized the effects of intracerebellar D-serine, indicating a central mechanism. However, direct co-injection of BMY-14802 into the cerebellum failed to antagonize the D-serine-induced increases in cGMP, indicating a locus of action outside the cerebellum. In contrast, quisqualate-induced cGMP increases were not attenuated by BMY-14802. These results indicate a functional modulation of the N-methyl-D-aspartate/glycine/phencyclidine/ion channel complex-mediated events by BMY-14802, possibly through a transsynaptic mechanism, thus representing the first in vivo demonstration of a sigma ligand modulation of a response mediated through the N-methyl-D-aspartate receptor complex.

Neuropharmacological characterization of 1-aminocyclopropane-1-carboxylate and 1-aminocyclobutane-1-carboxylate, ligands of the N-methyl-D-aspartate-associated glycine receptor

Following intravenous administration, 1-aminocyclobutane-1-carboxylate (ACBC, 100 mg/kg), a N-methyl-D-aspartate (NMDA)-associated glycine receptor antagonist, was eliminated with a T1/2 of 5 min in mouse brain and 4 min in rat cerebrospinal fluid (CSF). 1-Aminocyclopropane-1-carboxylate (ACC), a NMDA-associated glycine receptor agonist, was found to have a T1/2 of less than 5 min in mouse brain. ACC and ACBC did not alter basal cerebellar cGMP. Glycine and D-serine increased cGMP, and 1-hydroxy-3-aminopyrrolidone-2 (HA-966), a glycine antagonist, reversed the D-serine-induced increases in cGMP. In contrast, ACBC did not reverse the D-serine-induced increases in cGMP. These data suggest that despite their brain bioavailability and marked potency at the glycine receptor in vitro, ACC and ACBC are rapidly inactivated and thus have limited in vivo utility.

Sigma receptors modulate the hypothalamic-pituitary-adrenal (HPA) axis centrally: evidence for a functional interaction with NMDA receptors, in vivo

The present report investigates the modulation of the hypothalamic-pituitary-adrenal (HPA) axis in the rat by sigma receptors, using a selective ligand, (+) pentazocine, and comparing the effects with (+) SKF 10, 047. Both compounds stimulate ACTH release potently after central and peripheral administration. These effects are centrally mediated, since they did not release ACTH from anterior pituitary primary cultures. The effects are not blocked by naloxone, but are blocked by the NMDA antagonist, CPP, indicating a centrally mediated functional interaction between NMDA and sigma receptors, in vivo.

Continuity and change in preferred provider organizations

This paper presents the results from a national survey of preferred provider organizations (PPOs) that was conducted in 1988. It is based on telephone interviews conducted by the authors with executives in over 170 PPOs in the United States. We compare the survey results with those obtained from similar surveys conducted in 1985 and 1986, allowing us to assess the extent to which PPOs have grown and changed. We found that PPOs have continued to grow at an extremely rapid rate. During the Summer and Fall of 1988, the time in which the survey took place, 37.6 million people were eligible to use PPO benefits, compared to the 16.5 million figure we obtained two years earlier. We did not find, however, that PPOs are moving in the direction of providing more innovative forms of health care cost containment. Most PPOs still rely on discounts from providers and utilization review to achieve savings. There is little trend towards using incentive reimbursement techniques and choosing preferred providers that have shown themselves to be cost-efficient. We conclude that in the coming years PPOs must demonstrate the ability to control rising health care costs. To accomplish this, they will need to put more pressure on providers to use resources more sparingly. Otherwise, they may lose their market share to other forms of managed care.

In vivo modulation of the N-methyl-D-aspartate receptor complex by D-serine: potentiation of ongoing neuronal activity as evidenced by increased cerebellar cyclic GMP

Direct intracerebellar injections of N-methyl-D-aspartate (NMDA) or D-serine elicited dose-dependent increases in cerebellar cyclic GMP levels, in vivo in the mouse. The actions of D-serine were antagonized by the competitive NMDA receptor antagonist 3-(2-carboxypiperazin-4-yl) propyl-1-phosphonic acid and by the phencyclidine receptor agonist MK-801, observations supporting actions at the NMDA-coupled glycine receptor. In addition, the actions of D-serine were antagonized by a partial agonist (D-cycloserine) and an antagonist (HA-966) of the NMDA-coupled glycine receptor. These data are all consistent with D-serine acting at the NMDA-coupled glycine receptor and represent the first demonstration of glycine receptor potentiation of ongoing NMDA-mediated neuronal activity in the CNS, rather than potentiation of exogenous NMDA.