Postmortem studies in psychiatry

Neurochemical postmortem examination of brain tissue may never be completely replaced as a research tool in psychiatry. This method has already provided support for the hypotheses relating norepinephrine, dopamine, serotonin, peptides, and hemisphere asymmetries to psychiatric syndromes.     

Antisera specific for the oligoribonucleotide sequences AAU and A2U2 and their recognition of oligonucleotide conformation

Antisera specific for two synthetic oligoribonucleotide sequences, AAU and A2U2, were elicited in rabbits. The oligonucleotides were synthesized using polynucleotide phosphorylase under high salt conditions. Each oligomer was isolated by ion exchange chromatography, and was conjugated to bovine serum albumin, and injected into rabbits as an emulsion with complete Freund's adjuvant. The specificities of the resulting sera were analyzed using a modified Farr-type radioimmunoassay employing homologous oligonucleotide-protein conjugates radiolabeled with [3H]acetic anhydride and unlabeled free oligonucleotides as inhibitors. The antiserum elicited by AAU-BSA reacted well with AAU-RSA but a major fraction of the antibodies was directed to determinants of the conjugate that were not present on the free hapten. With respect to the haptenic determinants, AAU was a better inhibitor than any of the constituent mono- or dinucleotides, implying that features of the entire trinucleotide were being recognized. The other members of the A2Un family reacted to about the same extent as AAU, while other trinucleotides required an up to 21-fold higher concn in order to achieve similar inhibition. The most striking aspect of this antiserum was its failure to bind free ApA, although it could bind the ApA-containing oligonucleotides A3, AAG, AAC and A2Un. It seems likely that the ApA sequence in solution does not contain a significant proportion of a conformation present to a great extent in the ApA-containing oligomers. The antiserum elicited by A2U2-BSA was like anti-AAU-BSA in that some of the antibodies were directed against determinants not present on the free hapten. The most striking result of the inhibition experiments was the specificity of the antiserum for members of the A2Un series. When the A2Un series was compared with AA, AMP or any member of the Un series, approximately four orders of magnitude separated the inhibition curves. The poor binding of component mono- and dinucleotides implies that the conformation recognized by the antibody is present only to a significant extent in the trimeric sequence; the equality of binding of AAU with A2U2, A2U3 and A2U4 suggests that this conformation of the triplet is preserved in the longer sequences. These studies demonstrate the utility of immunochemical procedures for the study of oligonucleotide conformation in solution.     

PHOTOREGULATION OF BIOLOGICAL ACTIVITY BY PHOTOCHROMIC REAGENTS, III. PHOTOREGULATION OF BIOELECTRICITY BY ACETYLCHOLINE RECEPTOR INHIBITORS

The photochromic compounds N-p-phenylazophenyl-N-phenylcarbamylcholine chloride and p-phenylazophenyltrimethylammonium chloride inhibit the carbamylcholine-produced depolarization of the excitable membrane of the monocellular electroplax preparation of Electrophorus. The trans isomer of each predominates in the light of a photoflood (420 mmu) lamp; they are stronger inhibitors than the cis isomers, which predominate under ultraviolet (320 mmu) irradiation. The potential difference across the excitable membrane may be photoregulated by exposing an electroplax in the presence of a solution of carbamylcholine and either of the two compounds to light of appropriate wavelengths, since light shifts the cis-trans equilibrium. The system may be considered as a model illustrating how one may link a cis-trans isomerization, the first step in the initiation of a visual impulse, with substantial changes (20-30 mv) in the potential difference across an excitable membrane.     

Photochromic Activators of the Acetylcholine Receptor

Two photochromic activators of the electrogenic membrane of the electroplax of Electrophorus electricus are described. Trans-3,3'-bis[alpha-(trimethylammonium)methyl]azobenzene dibromide (Bis-Q), one of the most potent ever reported, is active at concentrations of less than 10(-7) M. Its cis isomer, which is obtained from the trans by exposure to light of 330 nm, is practically devoid of activity. Photoregulation of the potential of the membrane takes place in the presence of Bis-Q, presumably because of the conversion of the active trans isomer to the inactive cis isomer in the single-cell electroplax system. The second activator, 3-(alpha-bromomethyl)-3'-[alpha-(trimethylammonium)methyl]azobenzene bromide (QBr) can be covalently attached to the electroplax membrane after reduction of the membrane with dithiothreitol. Activation of the membrane is induced by the covalently linked reagent. Its cis isomer, obtained from the trans by exposure to light of 330 nm, is, like cis-Bis-Q, of very low activity. Both isomers of Bis-Q are equally active as inhibitors of acetylcholinesterase, 50% inhibition occurring at a concentration of 10(-5) M. The possibility of using trans-Bis-Q and trans-QBr to characterize and isolate the receptor protein is discussed.     

Cardiac physiologic and tissue metabolic changes following chronic low-level cadmium and cadmium plus lead ingestion in the rat

Female Long-Evans hooded rats received Schroeder's rye-based diet and 0 or 1 μg/ml cadmium, or cadmium plus lead in mineral fortified drinking water from weaning to 18 months. The heavy metal-fed rats were normal with respect to control, including growth rates and final body weights. Rats receiving added cadmium and cadmium plus lead in the diet were characterized by a persistent hypertension which was evident after 2 months. Cardiac conduction system excitability was depressed preferentially in cadmium- (atrioventricular nodal region) and cadmium plus lead- (His-Purkinje system) fed rats. Although heart rates were comparable to control, myocardial contractile activity (peak active tension and $\text{dT}\text{dt}$) was significantly decreased in intact perfused heart preparations from both heavy metal-treated groups. In conjunction with the observed physiologic changes, various tissue-specific metabolic alterations were detected in heart, kidney, and liver. Generally, prolonged heavy-metal ingestion at these levels resulted in impaired energy metabolism (e.g., decreased ATP, PCr; increased P_i, ADP concentrations) and altered essential mineral composition (e.g., calcium, magnesium, zinc, and to a lesser extent, sodium and potassium; copper levels were unaffected) that varied in severity according to the tissue. The addition of lead to the cadmium diet had little additive effect on the cardiovascular system; however, renal and hepatic tissues did exhibit apparent additive effects further suggesting that cadmium and lead actions and interactions may be tissue dependent. These experimental findings and the biologic inferences derived are consonant with the hypothesis that chronic, life-long cadmium exposure approximating environmental levels may have significant adverse effects on mammalian systems, that include effects on cardiovascular tissues.     

B lymphocyte stimulator expression in pediatric systemic lupus erythematosus and juvenile idiopathic arthritis patients

Objective

To assess the expression of B lymphocyte stimulator (BLyS) in patients with pediatric systemic lupus erythematosus (SLE) or juvenile idiopathic arthritis (JIA).

Methods

Blood samples collected from patients with pediatric SLE (n = 56) and patients with JIA (n = 54) at the beginning and end of a 6‐month interval were analyzed for plasma BLyS protein levels by enzyme‐linked immunosorbent assay and for blood leukocyte full‐length BLyS and ΔBLyS messenger RNA (mRNA) levels by quantitative real‐time polymerase chain reaction (normalized to 18S expression). Healthy siblings (n = 34) of these patients served as controls.

Results

In pediatric SLE, plasma BLyS protein and blood leukocyte BLyS mRNA levels were each significantly elevated, and plasma BLyS protein levels, but not blood leukocyte BLyS mRNA levels, were correlated with disease activity. In contrast, plasma BLyS protein levels were normal in JIA despite blood leukocyte BLyS mRNA levels being elevated to degrees similar to those in pediatric SLE. Among JIA patients, neither BLyS parameter was correlated with disease activity. In both pediatric SLE and JIA, the BLyS expression profiles remained stable at 6 months.

Conclusion

Our findings indicate that, as previously noted in adult SLE, plasma BLyS protein and blood leukocyte BLyS mRNA levels are elevated in pediatric SLE. The correlation of plasma BLyS protein levels with disease activity points to BLyS as a candidate therapeutic target in pediatric SLE. Contrary to previous observations in adults with rheumatoid arthritis, plasma BLyS protein levels are normal in JIA despite elevated blood leukocyte BLyS mRNA levels. The absence of correlation between either of the BLyS parameters and disease activity in JIA calls for circumspection prior to assigning BLyS as a candidate therapeutic target in this disorder.