Beta-endorphin blunts phosphatidylinositol formation during in vitro activation of isolated human lymphocytes: preliminary report

We have previously described the regulatory effect of beta-endorphin on three human cytotoxic cell populations. We confirmed the variable nature of these effects on human natural killer cell (NK) activity, showed mixed effects on the generation of cytotoxic T lymphocyte (CTL) activity, and demonstrated the reproducible suppression of lymphokine-activated killer cell (LAK) activity. We and others also observed mixed effects of beta-endorphin on the proliferative response to mitogens and in mixed leukocyte reactions. In the study reported here, we test the effects of beta-endorphin on the formation of phosphatidylinositol during cell activation. 32P-radiolabeled peripheral blood mononuclear cells obtained from normal adult donors and CD2-depleted subpopulations were activated with phytohemagglutinin or in a NK, LAK, or CTL protocol in the absence or presence of recombinant beta-endorphin. The total lipidic extract was analyzed by thin-layer chromatography and autoradiography. The results of these studies indicate that beta-endorphin blunts the formation of phosphatidylinositol by about 20% in the four systems studied and in all the donors tested. This effect is dose-dependent and is blocked in part by the opioid antagonist, naltrexone, suggesting involvement of the opioid receptor.

Carbachol potentiates isoprenaline-induced mucin secretion by rat submandibular gland

We studied the effects of carbachol on isoprenaline-induced secretion of 3[H]glucosamine-labeled high molecular weight protein from in vitro fragments of rat submandibular gland. The concentration-response curve for isoprenaline was determined alone and in the presence of one of two concentrations of carbachol. Isobolic interaction indices were calculated from the resulting curves. The role of extracellular calcium on this interaction was assessed by examining the effect of increasing concentrations of [Ca2+]e on secretion induced by a fixed concentration of isoprenaline alone and in the presence of carbachol. Carbachol alone caused a small, but statistically significant, protein secretion. Carbachol markedly shifted the isoprenaline concentration-response curve to the left in a dose-dependent manner. In the absence of extracellular calcium, carbachol did not increase isoprenaline-induced secretion, but secretion increased as the [Ca2+]e was increased. The carbachol-induced increase in secretion reached a maximal level at approximately 2.0 mM [Ca2+]e. We conclude that carbachol's increase of isoprenaline-induced secretion of 3[H]glucosamine-labeled high molecular weight protein is not additive, but is true potentiation. This potentiation requires extracellular calcium, and may be maximal at physiological [Ca2+]e.

[Evaluation of the efficacy of mannitol in the treatment of ciguatera in French Polynesia]

Up till now, in the French Polynesia and in New Caledonia, people showing ciguatera intoxication receive a standard treatment: calcium + vitamins B6 and C by intravenous way and in addition, some drugs arriving to cure some symptomatic manifestations. In 1988, an investigation carried out in Majuro, Marshall Islands concluded that intravenous mannitol is efficient in the treatment of serious intoxications with suspecting cerebral oedema. Since, such a treatment has been utilized with success in several endemic areas. Our therapeutic evaluation was arrived to determine whether mannitol's efficiency is higher than the standard treatment in the ciguatera intoxications of mean seriousness. This investigation was carried out on two randomized groups: The first one receiving mannitol (250 cc intravenous at 20% injected in 1 h) the second one receiving the standard treatment (intravenous perfusion glucose serum 250 cc with 1 g of vitamins C, 250 mg of vitamin B6 and 1 g of calcium gluconate injected in 1 h). Seriousness of clinical status was evaluated according to a scale of score from 0 to 50, based on the importance of the clinical manifestations paresthesia, aches, asthenia, cardiovascular and digestive signs. Only patients getting a score at least 20 were included in this investigation. Clinical status of each patient was evaluated before any treatment (initial score) at the end of perfusion and at the 24th hour. Efficiency of each treatment respectively was evaluated according to the differences between these three different scores. CHI 2 and U Mann's and Whitney's tests were utilized for the statistical analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Cumulative mortality rates in Aedes polynesiensis after feeding on polynesian Wuchereria bancrofti carriers treated with single doses of ivermectin, diethylcarbamazine and placebo

During a therapeutic trial, batches of 672 to 1979 laboratory-bred Aedes polynesiensis, the mosquito vector of lymphatic filariasis in French Polynesia, were fed on Wuchereria bancrofti carriers one, three and six months after they had been treated with either single doses of ivermectin at 100 mcg/kg, diethylcarbamazine (DEC) at 3 and 6 mg/kg or placebo. High mortality rates were observed during the 15-day period following the blood-meal in mosquitoes fed on carriers treated with microfilaricidal drugs and were significantly higher in mosquitoes fed on carriers treated with ivermectin than in those fed on carriers treated with DEC. Though its intensity decreased with the passage of time, the phenomenon was observed in mosquitoes fed on carriers up to six months after treatment, especially in those fed on carriers treated with ivermectin. By decreasing the number of mosquitoes able to transmit the infection, this lethal effect on Ae. polynesiensis might represent an additional advantage of ivermectin in lymphatic filariasis control programs.

The treatment of microfilaremia due to Wuchereria bancrofti var. pacifica: ivermectin versus diethylcarbamazine

In October 1989, a controlled, double-blind parallel group trial was implemented to compare both efficacy and tolerability of single doses of ivermectin and diethylcarbamazine (DEC). Fifty eight apparently healthy Wuchereria bancrofti carriers were hospitalized and randomly allocated to treatment with ivermectin 100 mcg/kg, DEC 3 or 6 mg/kg. Six months later, half of those initially treated with ivermectin 100 mcg/kg and DEC 3 mg/kg were given a second similar dose while the rest were given a placebo. After initial treatment, clearance of microfilaremia was complete in 22 of the 23 carriers treated with ivermectin and in one only of the 35 treated with DEC. Adjusted geometric mean microfilaremia was significantly lower (p less than 0.01) in carriers treated with ivermectin than in those treated with DEC at one, but neither at 3 (p = 0.26) nor at 6 months (p = 0.63). The comparison of adjusted geometric mean microfilaremia per group indicated that (i) regarding either ivermectin 100 mcg/kg or DEC 3 mg/kg, 2 successive doses resulted in higher efficacy than one annual dose and (ii) efficacy of 2 successive doses of ivermectin 100 mcg/kg or DEC 3 mg/kg were not significantly different. During the 3 days following initial treatment, adverse reactions were observed in 80% of the treated carriers of whom 14% suffered a grade 3 reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Polyamines in the anemia of end-stage renal disease

The improvement in the anemia in patients with end-stage renal disease (ESRD) on continuous ambulatory peritoneal dialysis (CAPD) suggests that dialyzable substances present in the sera of uremic patients either inhibit erythropoiesis directly or inactivate erythropoietin (EPO). In the present study predialysis sera from patients with ESRD inhibited erythroid colony (CFU-E) (N = 10) formation to a significantly (P less than 0.01) greater degree than granulocyte-macrophage (CFU-GM) (N = 7) colony formation in mouse bone marrow (MBM) cultures. The polyamines spermine (SP) (18 to 560 nm/ml) and spermidine (SD) (4 to 648 nm/ml) exerted a more significant (P less than 0.05) inhibition of CFU-E (N greater than or equal to 5) than that of CFU-GM (N greater than or equal to 5) growth. Concentrations of 0.80, 1.0, and 1.5 nm/ml of putrescine (PU) were 92%, 85%, and 77% of erythroid colony (CFU-E) controls (N = 4) and 104%, 130%, and 127% of CFU-GM controls (N = 4). Putrescine (PU) at 1.5 nm/ml also produced a significant (P less than 0.05) inhibition of CFU-E, whereas CFU-GM were stimulated by PU. These data suggest that predialysis sera from uremic patients, as well as SP, SD, and PU, are selectively more inhibitory to CFU-E than CFU-GM growth. The immunoreactivity of EPO was not significantly changed when it was coincubated with SP, SD and PU and measured by radioimmunoassay. PU was found to inhibit noncompetitively the bioactivity of EPO in a CFU-E assay. These data support the hypothesis that polyamines may be important uremic toxins in the anemia of ESRD.

Interleukin-1 beta stimulates bone resorption and inhibits bone formation in vivo

Interleukin-1 beta (IL-1 beta) and several other cytokines, including IL-1 alpha, tumor necrosis factor (TNF), and lymphotoxin, stimulate bone resorption and also inhibit bone formation in vitro. These effects are consistent with an uncoupling function for these mediators, although the effect of in vivo regulatory mechanism(s) that couple resorption and formation cannot be adequately evaluated in vitro. In the present studies, the effect of IL-1 beta on bone resorption and formation was determined in adult rats in vivo. Resorption was assessed by serum and urinary calcium levels, osteoclast number, and active resorption surface. Bone formation was determined by measurement of serum osteocalcin levels, and by quantitation of bone apposition rate using tetracycline labeling. A modest dose of IL-1 beta (1 microgram/kg) was found to stimulate transient increases in serum calcium, and a persistent elevation of urinary calcium excretion. IL-1 beta treatment also resulted in decreases in serum iron levels and in the albumin/globulin ratio, well-established in vivo effects of IL-1. SGOT, SGPT, BUN, creatinine, and total protein were unaffected, indicating that IL-1 beta treatment did not compromise kidney or liver function, and that animals were systemically healthy. This was further evidenced by normal weight gain in IL-1 beta-treated animals. Low doses (50 micrograms/kg) of synthetic human parathyroid hormone (PTH 1-34) also stimulated resorption, as shown by a sustained increase in serum calcium without increased urinary excretion. Both IL-1 beta and parathyroid hormone (PTH) stimulated similar increases in osteoclast number (N.Oc) and active resorption surface [Oc.S(%)].(ABSTRACT TRUNCATED AT 250 WORDS)

Double blind study on efficacy and safety of single doses of ivermectin and diethylcarbamazine for treatment of Polynesian Wuchereria bancrofti carriers. Results at six months

In 1989, a double-blind trial was implemented in Tahiti to compare both efficacy and tolerability of single doses of ivermectin and diethylcarbamazine (DEC) for treatment of Wuchereria bancrofti carriers. Of 58 carriers, in whom microfilarial (mf) density was greater than or equal to 100 mf/ml, 23, 24 and 11 were randomly allocated to treatment with respectively ivermectin 100 mcg/kg, DEC 3 and DEC 6 mg/kg. One week after treatment, clearance of microfilaremia was complete in 22 of the 23 carriers treated with ivermectin and in one only of the 35 treated with DEC. Adjusted geometric mean for mf densities was significantly lower (p less than 0.001) in carriers treated with ivermectin than in those treated with DEC at one, but neither at 3 (p = 0.26) nor at 6 months (p = 0.63). At 3 and 6 months, mf levels were 14 and 28%, 21.6 and 19.4%, and 10.2 and 8.4% of pretreatment mf levels in carriers treated respectively with ivermectin 100 mcg/kg, DEC 3 and DEC 6 mg/kg. Side effects were experienced by 51 carriers (88%) of whom only 8 (14%) suffered a grade 3 reaction. Onset and intensity of side effects were significantly associated (p less than 0.01) with both pretreatment mf densities and peripheral blood parasite clearance. Efficacy of ivermectin single dose was superior to that of DEC single dose in terms of immediate mf clearance but not in terms of sustained mf decrease at 6 months.

Differential effect of beta-endorphin on three human cytotoxic cell populations

We have examined in vitro the effect of the proopiomelanocortin gene product, beta-endorphin (bE), on the cytotoxic activity of natural killer (NK) cells, lymphokine activated killer (LAK) cells and cytotoxic T-lymphocytes (CTL). Our studies show that bE reproducibly suppressed LAK cytotoxic activity in all donors tested. The effect of bE on the generation of CTL varied, and was negligible on CTL cytotoxic function. Our study also confirms the variable nature of the effects of bE on NK cytotoxicity. In all instances, the effects of bE were generally small, but could be blocked by opioid receptor antagonists, or by prior heat-inactivation of the peptide. The magnitude of the effects was greatest at low effector:target ratios in all of the three systems studied. These results support the emerging body of evidence that the neuroendocrine system may influence host defense mechanisms mediated by cytotoxic cells.

Pituitary-adrenal-immune system in normal subjects and in patients with anorexia nervosa: the number of circulating helper T lymphocytes (CD4) expressing the homing receptor Leu8 is regulated in part by pituitary-adrenal products

The association between plasma pituitary-adrenal (PA) hormones and the number of certain populations of peripheral blood lymphocytes (PBL) was examined in subjects with normal PA function and in patients with anorexia nervosa (AN). AN patients display several neuroendocrine dysfunctions, including hypercortisolemia. In the normal subjects there were positive correlations between adrenocorticotropic hormone (ACTH) and the number of PBL and helper T lymphocytes expressing the homing receptor Leu8 (CD4+Leu8+); there was a negative relationship between cortisol and these lymphocyte populations. These latter, inverse correlations did not occur in the AN patients, either while underweight or after weight recovery, with some persistence of hypercortisolemia. Administration of dexamethasone (DEX) suppressed cortisol levels and reduced, perhaps via a receptor-mediated mechanism, the number of circulating PBL and CD4+Leu8+ in the normal subjects but not in the AN patients. These results support the physiological relevance of PA-CMI interaction in subjects with normal PA function and indicate that the PA-CMI interrelationship is disrupted in AN patients with hypercortisolemia.

Prostatic acid phosphatase in serum of patients with prostatic cancer is a specific phosphotyrosine acid phosphatase

We developed an assay to measure at acid pH the phosphotyrosine phosphatase activity in sera from patients with prostatic cancer. The method used quantifies the inorganic phosphate liberated from phosphotyrosine after incubation with serum, followed by the deproteinization of the reaction mixture. A high acid phosphatase (EC 3.1.3.2) activity towards phosphotyrosine was observed in all sera from patients with increased activity of prostatic acid phosphatase. This activity represented 96% of prostatic acid phosphatase and 77% of total acid phosphatase activities. Moreover, it was correlated (r = 0.91) with the amount of serum prostatic acid phosphatase determined by radioimmunoassay. When serum acid phosphatase activity was measured on several phosphorylated substrates, preferential hydrolysis was demonstrated for those in which the phosphate group was esterified on an aromatic ring rather than those presenting an aliphatic chain. Among phosphoamino acids, only phosphotyrosine was a good substrate, with little or no activity observed with phosphoserine and phosphothreonine. Human seminal plasma and partially purified prostatic acid phosphatase, tested for their activity on some of these substrates, gave similar results. On the other hand, sera from patients with above-normal alkaline phosphatase activity and no prostatic disease showed little or no activity on phosphotyrosine at both acid and alkaline pH values. Evidence is presented that the prostatic acid phosphatase in serum is a specific phosphotyrosine acid phosphatase.

Feedback regulation of bile-acid synthesis in the rat. Differing effects of taurocholate and tauroursocholate

We studied the effect of the orientation of the 7-hydroxyl group in taurocholate (7 alpha) and tauroursocholate (7 beta) on the feedback regulation of bile-acid synthesis and its rate-controlling enzyme, cholesterol 7 alpha-hydroxylase, in bile-fistula rats. To ensure a constant supply of cholesterol and to label newly synthesized bile acids, RS[2-14C]mevalonolactone was infused intraduodenally at 154 mumol/h before and during bile-acid infusion. Mevalonolactone inhibited hydroxymethyl-glutaryl CoA reductase activity 90% but did not increase bile-acid synthesis and cholesterol 7 alpha-hydroxylase activity. When sodium taurocholate was infused at the rate of 27 mumol/100 g rat per h (equivalent to the hourly hepatic bile-acid flux), bile-acid synthesis decreased 82% and cholesterol 7 alpha-hydroxylase activity declined 78%. This inhibitory effect was observed in the absence of hepatic damage. In contrast, sodium tauroursocholate infused at the same rate did not decrease bile-acid synthesis nor cholesterol 7 alpha-hydroxylase activity. Hepatic cholesterol content rose 36% with sodium taurocholate but did not change during sodium tauroursocholate administration. These results demonstrate that the feedback inhibition of bile-acid synthesis is mediated through the regulation of cholesterol 7 alpha-hydroxylase. In these experiments, taurocholate was a far more potent inhibitor than its 7 beta-hydroxy epimer, tauroursocholate.

Unexpected failure of bile acid malabsorption to stimulate cholesterol synthesis in sitosterolemia with xanthomatosis. Comparison with lovastatin

We examined the relationship between cholesterol synthesis and high affinity low density lipoprotein (LDL) catabolism in freshly isolated mononuclear leukocytes and plasma sterols and apolipoprotein concentrations in three homozygous and one heterozygous subject with sitosterolemia with xanthomatosis and in 12 control subjects. Observations in untreated subjects were compared during therapy with lovastatin or interruption of the enterohepatic circulation of bile acids. Plasma cholesterol, plant sterol, and apolipoprotein B concentrations declined more than 50% in the two homozygous sitosterolemic subjects after ileal bypass surgery. In contrast, plasma cholesterol, plant sterol, and apolipoprotein B concentrations remained constant in a homozygous sitosterolemic subject and declined only 7% in a heterozygous sitosterolemic subject during 20 weeks of lovastatin (40 mg/day) treatment compared to a 28% decrease in similarly treated control subjects. Lovastatin treatment decreased cholesterol synthesis more than 60% but did not increase high affinity catabolism of LDL further in the sitosterolemic cells, compared to a more than 20% rise in control mononuclear leukocytes. Conversely, bile acid malabsorption increased cholesterol synthesis 59%, total hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase activity 13%, and receptor-mediated LDL degradation 41% in control cells, but did not stimulate cholesterol synthesis or microsomal HMG-CoA reductase activity in sitosterolemic mononuclear leukocytes although receptor-mediated LDL catabolism rose an additional 26%. These results demonstrate a greater than expected decrease in plasma sterols and apolipoprotein B concentrations in sitosterolemic subjects after stimulation of bile acid synthesis because of the inability to up-regulate cholesterol production. We suggest that bile acid-sequestering drugs or ileal exclusion surgery may be more effective treatments to mobilize accumulated sterol deposits and prevent atherosclerosis in this disease.

[Perpropionic and peracetic acids destroy HIV in suspension, but do not inhibit the virus in contaminated units of blood]

The virucidal activity of peracetic and perpropionic acids was evaluated against HIV in an attempt to inactivate the virus which might contaminate blood units collected from donors. The results showed first that doses of peracids as weak as 50 ppm were able to kill the virus in free suspension, but that the doses that did not adversely affect blood components did not inactivate the virus in those components.

Increased sitosterol absorption, decreased removal, and expanded body pools compensate for reduced cholesterol synthesis in sitosterolemia with xanthomatosis

We measured the turnover and absorption of sitosterol and cholesterol, along with plasma sterol and lipoprotein concentrations, in one control and two subjects with sitosterolemia with xanthomatosis. All individuals consumed the same diet which contained approximately 500 mg/day of cholesterol and 250 mg/day of sitosterol. Sterol absorption was measured by the plasma dual-isotope ratio method and turnover by plasma isotope-kinetic analysis. In two sitosterolemic subjects, 28% and 63% of the sitosterol and 69% and 49% of the cholesterol were absorbed, respectively, compared to 4% of the sitosterol and 44% of the cholesterol in the control. As expected, plasma sitosterol specific activities decayed much more rapidly than cholesterol in the control subject. In contrast, plasma sitosterol and cholesterol specific activity-time curves were similar and decayed more slowly in the sitosterolemic subjects. In the control subject, the total sitotterol pool was 290 mg and was linearly related to low absorption (18 mg/day); whereas the total sitosterol pool was 17 times (4800 mg) and 13 times (3500 mg) larger, respectively, in the sitosterolemic subjects and was expanded out of proportion to increased absorption because of decreased removal. Daily cholesterol turnover and synthesis were markedly reduced in the sitosterolemic subjects. In four sitosterolemic subjects, plasma concentrations of total sterols, low density lipoproteins, and apolipoprotein B were increased, while those of high density lipoproteins and apolipoprotein A-I were low to normal. The low density lipoproteins were very similar to those of normal control subjects in density distribution, peak flotation rate, sterol-to-protein (apolipoprotein B) ratio, particle size, and morphology. These results demonstrate in patients with sitosterolemia with xanthomatosis that: 1) the absorption of sitosterol and cholesterol is enhanced; 2) tissue recognition between cholesterol and sitosterol is lost; 3) total exchangeable sitosterol pools are expanded out of proportion to absorption because of decreased excretion; 4) plasma sterol and lipoprotein concentrations favor tissue deposition; and 5) cholesterol synthesis is diminished. We postulate that the changes in sitosterol metabolism (increased absorption, loss of tissue sterol structural recognition, expanded pools, and hepatic retention) are a response to reduced cholesterol synthesis in these subject.

Automated electrocardiogram analysis: the state of the art

The overwhelming number of electrocardiograms (ECGs) now recorded routinely has prompted the development of computer analysis which in turn has benefited electrocardiography with important technological advances. All automated ECG analysis systems adopt a similar approach: a measurement program and a program that interprets the clinical significance of these measurements along with a rhythm analysis algorithm. Measurement, selection and classification of parameters vary according to the program used. Data compression is applied to the signal to reduce processing time and allow long-term storage. Diagnostic accuracy, however, is not greatly improved over that of experienced cardiologists. Programs studied using a validated data bank provided by an international group of cardiologists show a variability not only in parameter measurement but also in diagnostic statement and in the way in which such statements are expressed. Recommendations for measurement standards have been made to fulfil the need for exchange of diagnostic criteria. No recommendations concerning the selection of parameters have been proposed, and so new parameters or combinations of parameters can be introduced with the ultimate aim of increased diagnostic performance.

Practice patterns, attitudes and activities of Caucasian vs. Asian University of California-San Francisco PharmD graduates

The results of a 1982 survey of graduates of the University of California at San Francisco (UCSF) doctor of pharmacy degree program were re-analyzed to explore whether cultural differences between Asian and Caucasian PharmD graduates affected professional practice patterns, attitudes and activities. Of the 732 respondents, 408 (56 percent) were Caucasians and 262 (36 percent) were Asians. Asian females had significantly fewer years of college education before entering pharmacy school and spend significantly fewer hours in the practice of pharmacy or related activities. Caucasians had a slightly higher grade point average than Asians. The mean score on the California State Board of Pharmacy Licensure Examination did not differ between the groups. For their first position following graduation, Asians predominated in operational positions, while Caucasians held clinical positions more frequently. Thirty-eight percent of Caucasians vs. 18 percent of Asians were taking or had completed postgraduate residency or fellowship training. An analysis of current jobs revealed that Asian males had the greatest increase in clinical positions when compared to the first position. Males of both ethnicities made the greatest gains in annual salary and in management positions compared to females.

Competitive inhibition of bile acid synthesis by endogenous cholestanol and sitosterol in sitosterolemia with xanthomatosis. Effect on cholesterol 7 alpha-hydroxylase

The 7 alpha-hydroxylation of two cholesterol analogues, sitosterol and cholestanol, and their effect on the 7 alpha-hydroxylation of cholesterol were measured in rat and human hepatic microsomes. In untreated rat liver microsomes, the 7 alpha-hydroxylation of cholesterol was higher than that of cholestanol (1.4-fold) and sitosterol (30-fold). After removal of endogenous sterols from the microsomes by acetone treatment, the 7 alpha-hydroxylation of cholesterol was similar to that of cholestanol and only fourfold higher than that of sitosterol. Cholestanol and sitosterol competitively inhibited cholesterol 7 alpha-hydroxylase in both rat and human liver microsomes, with cholestanol the more potent inhibitor. Patients with sitosterolemia with xanthomatosis, who have elevated microsomal cholestanol and sitosterol, showed reduced cholesterol 7 alpha-hydroxylase activity relative to the activity in control subjects (13.9 and 14.7 vs. 20.3 +/- 0.9 pmol/nmol P-450 per min, P less than 0.01). Enzyme activity in these patients was 40% higher when measured in microsomes from which competing sterols had been removed. Ileal bypass surgery in one sitosterolemic patient decreased plasma cholestanol and sitosterol concentrations and resulted in a 30% increase in hepatic microsomal cholesterol 7 alpha-hydroxylase activity. Cholesterol 7 alpha-hydroxylase appears to have a specific apolar binding site for the side chain of cholesterol and is affected by the presence of cholestanol and sitosterol in the microsomal substrate pool. Reduced bile acid synthesis in sitosterolemia with xanthomatosis may be related to the inhibition of cholesterol 7 alpha-hydroxylase activity by endogenous cholesterol analogues.

Two classes of N-methyl-D-aspartate recognition sites: differential distribution and differential regulation by glycine

The N-methyl-D-aspartate (NMDA) receptor, a subtype of excitatory amino acid receptor, mediates synaptic responses in many regions of the central nervous system. This receptor plays a critical role in the mechanisms of both synaptic plasticity and excitotoxicity. Although these receptors were generally thought to be a single homogeneous receptor population, we report observations indicating that two anatomically distinct forms of the NMDA-receptor complex exist. (i) The distribution of NMDA receptors, as labeled by the NMDA agonist L-[3H]glutamate, differs from that obtained with the radiolabeled antagonist 3H-labeled 3-[(+/-)2-carboxypiperazine-4-yl]propyl-1-phosphonic acid [( 3H]CPP). Relative to L-[3H]glutamate, [3H]CPP binding is low in the striatum and septum and high in the thalamus and inner cerebral cortex. (ii) NMDA antagonists are relatively more potent than agonists at displacing L-[3H]glutamate binding in the thalamus and cerebral cortex; agonists are relatively more potent in the striatum and cerebellum. (iii) Glycine, which potentiates NMDA-receptor responses to glutamate, causes a greater percentage increase in L-[3H]glutamate binding to NMDA receptors in the thalamus and cerebral cortex than in the striatum, septum, and cerebellum. Radiolabeled NMDA-antagonist binding, in contrast, is inhibited by glycine. Thus, as observed for gamma-aminobutyric acid type A receptors, NMDA receptors have an agonist-preferring binding-site population and an antagonist-preferring binding site population. These may represent two distinct receptors and/or two interconverting forms. It could be of significant clinical importance if these two sites differ in their response to NMDA.

An Intelligent Display System for psychiatric education in primary care

We have shown how new concepts for displaying knowledge and data may overcome some of the limitations of existing decisionmaking and educational aids and how they may improve psychiatric diagnosis and education. Elsewhere, we illustrated how these concepts can also be applied in redesigning ordinary textbooks in many other areas of medicine. Using such ideas to simplify decisionmaking without oversimplifying and without reducing physician participation may help us to cope with the enormous growth of information and knowledge. This is a problem common to many areas of medicine, one that demands new ways of thinking about how to simplify educational methods.

The distribution of [3H]kainate binding sites in primate hippocampus is similar to the distribution of both Ca2+-sensitive and Ca2+-insensitive [3H]kainate binding sites in rat hippocampus

The distribution of [3H]kainate binding sites was determined by quantitative autoradiography in three vertebrate species: rat, monkey, and human. These animals displayed a similar pattern of binding site density in the hippocampus. Highest levels were found within the stratum lucidum and moderate levels in the inner portion of the dentate gyrus molecular layer. Although the distribution is similar, there is a lower density of binding sites in the stratum lucidum of primates than in rodents. Experiments using rat brain synaptic plasma membrane fractions indicated that inclusion of Ca2+ ions results in a selective reduction in binding at the high affinity sites. The Ca2+-inhibited and Ca2+-inhibited binding sites in the high affinity sites. The Ca2+ -inhibited and Ca2+ -insensitive binding sites in the rat hippocampus exhibited a similar distribution. Together, these results suggest that in a variety of mammalian species kainate receptors exhibit similar regional distributions, and that the high and low affinity kainate binding sites also exhibit similar regional distributions.