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M Banay-Schwartz

Publications and source records attributed to M Banay-Schwartz.

At least 37 records · Page 2Linked to original sources
PubMed1990

Calpain II activity and calpastatin content in brain regions of 3- and 24-month-old rats.

In previous studies, we found a significantly higher (100% or more) content of cathepsin D in the aging brain. In the present study, we determined activity of Ca2(+)-activated neutral protease requiring millimolar Ca2+ (calpain II, CANP II) and amount of its endogenous inhibitor, calpastatin, in extracts of various brain regions of 3-month-old and 24-month-old male Fischer-344 rats. Calpain II was separated from calpastatin in a single step (chromatography) and its activity was tested using as substrates [methyl-14C]alpha-casein, the cytoskeletal proteins desmin and actin, and a mixture of neurofilament triplet proteins and glial fibrillary acidic proteins (GFAP). We found no changes in calpain II activity in pons-medulla and spinal cord, but significant increases were detected in cortex (72%) and striatum (63%) of the 24-month-old rats using [methyl-14C]alpha-casein as substrate. The profile of desmin and actin breakdown showed regional variations somewhat different from those of [methyl-14C]alpha-casein. With desmin, the greatest increases with age were in the striatum (82%) and hypothalamus (46%), but there were no alterations in cortex, cerebellum, and pons-medulla. With actin, slightly enhanced activity in cortex and cerebellum was noticeable. Calpastatin content in brain regions was also increased, with the regional pattern of increase fairly similar to the pattern of enzyme activity increase. The causes and the physiological consequences of increased calpain and calpastatin content in the aged brain are being investigated. That changes with age are somewhat different with the various brain protein substrates indicates that some of the properties of the enzyme also undergo alteration with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1990

Plasma tryptophan to large neutral amino acid ratios in depressed and normal subjects.

The ratios of total and free plasma tryptophan to the sum of five large neutral amino acids (LNAAs) were found to be significantly lower in a group of 16 depressed inpatients compared to nine normal subjects after oral loading with L-tryptophan. The group differences in these ratios were significant before, and 2 weeks after starting treatment with a tricyclic antidepressant. Plasma tryptophan ratios and severity of depression were not significantly correlated.

Adolescent↗
PubMed1989

Amino acid analysis using 1-naphthylisocyanate as a precolumn high performance liquid chromatography derivatization reagent.

A method which uses 1-naphthylisocyanate as an HPLC precolumn derivatization reagent for amino acid analysis is described. Derivatization is carried out by adding the isocyanate dissolved in dry acetone to a buffered amino acid solution followed by extraction of the excess reagent with cyclohexane. The resulting naphthylcarbamoyl amino acids are stable and highly fluorescent, with excitation maxima at 238 and 305 nm and an emission maximum at 385 nm, for most amino acids. Ultraviolet detection near 222 nm, the absorption maximum, can also be employed. HPLC procedures permitting the analysis of protein hydrolysates, brain extract, cerebrospinal fluid, and blood plasma are presented. The method is particularly suitable for auto-sampler procedures since samples can be derivatized and diluted in advance and stored at room temperature in the sampler while awaiting injection. Other advantages include high sensitivity, the possibility of recovering the derivatives from the column effluent, and the absence of a reagent peak in the chromatograms.

1-Naphthylisothiocyanate↗
PubMed1989

Increase in cathepsin D activity in rat brain in aging.

Cathepsin D-like activity in homogenates of five brain areas of 3-month-old and 24-month-old Fischer 344 rats was measured. With hemoglobin as substrate at pH 3.2, more than 90% of the activity was inhibited by pepstatin. In each area studied, activity was more than twice as high in the old rat brain: 140-160% higher in the cortex, cerebellum, pons-medulla, and striatum and 90-100% higher in the hippocampus and spinal cord. The greatly increased metabolic capacity in the absence of an increase in protein turnover may have a role in age-related pathological degeneration in the brain.

Aging↗
PubMed1989

Changes with aging in the levels of amino acids in rat CNS structural elements. I. Glutamate and related amino acids.

Glutamate and related amino acids were determined in 53 discrete brain areas of 3- and 29-month-old male Fischer 344 rats microdissected with the punch technique. The levels of amino acids showed high regional variation - the ratio of the highest to lowest level was 9 for aspartate, 5 for glutamate, 6 for glutamine, and 21 for GABA. Several areas were found to have all four amino acids at very high or at very low level, but also some areas had some amino acids at high, others at low level. With age, in more than half of the areas, significant changes could be observed; decrease occurred 5 times more frequently than increase. Changes occurred more often in levels of aspartate and GABA than in those of glutamate or glutamine. The regional levels of glutamate and its related amino acids show severalfold variations, with the levels tending to decrease in the aged brain.

Aging↗
PubMed1989

Changes with aging in the levels of amino acids in rat CNS structural elements. II. Taurine and small neutral amino acids.

Taurine (Tau) and the small neutral amino acids glycine (Gly), serine (Ser), threonine (Thr), and alanine (Ala) were measured in 53 brain areas of 3- and 29-month-old male Fisher 344 rats. The ratio of highest to lowest level was 34 for Tau, 9.1 for Thr, 7.6 for Gly and Ser, and 6.5 for Ala. The heterogeneity was found in numerous areas; for example, Tau levels were more than 90 nmol/mg protein in 6 areas, and less than 20 nmol/mg protein in 10 areas. Similar heterogeneity was found with the other amino acids. The relative distribution of the small neutral amino acids showed several similarities; Tau distribution was different. With age, four amino acids decreased in 10-18 areas, and increased in only 1-3, while Thr increased in more areas than it decreased. The five amino acids of this paper, and the four of the previous paper, are among the amino acids at highest level in the brain; the sequence in their levels shows considerable regional heterogeneity.

Aging↗
PubMed1989

The presence of ATP + ubiquitin-dependent proteinase and multicatalytic proteinase complex in bovine brain.

The presence of two distinct high-molecular-weight proteases with similar pH optima in the weakly alkaline region was shown in cytosol of the bovine brain cortex. They were separated by ammonium sulfate fractionation and each was further purified by DEAE-Sephacel, Sephacryl S-300, DEAE-Cibacron Blue 3GA-agarose, heparin-agarose, and Sepharose 6B chromatography. The larger enzyme (Mr 1,400 kDa), which precipitates at 0-38% ammonium sulfate saturation, seems to be active in ATP + ubiquitin (Ub)-dependent proteolysis; it has low basal caseinolytic activity that is stimulated 3-fold by ATP, and when Ub is present ATP causes a 4.5-fold stimulation. A second proteinase was also found to be present (Mr 700 kDa) that precipitates at 38-80% ammonium sulfate saturation, is composed of multiple subunits ranging in Mr from 18 to 30 kDa, and degrades both protein and peptide substrates, demonstrating trypsin-, chymotrypsin- and cucumisin-like activities. Catalytic, biochemical, and immunological characteristics of this proteinase indicate that it is a multicatalytic proteinase complex (MPC), whose enzyme activity, in contrast to that of MPC from bovine pituitaries (1-3), is stimulated 1.7-fold by addition of ATP in the absence of ubiquitin at the early steps of purification; this property is lost during the course of further purification. Both proteinases are present in the nerve cells, since the primary chicken embryonic telencephalon neuronal cell culture extracts contain both ATP + Ub-dependent proteinase and MPC activities.

Adenosine Triphosphate↗
PubMed1989

The effect of caffeine on some mouse brain free amino acid levels.

Changes in free amino acids were examined in the central nervous system of mice treated with caffeine for three weeks. Caffeine was administered in the drinking water, and at the end of three weeks the level of caffeine in the cerebral cortex was 113 +/- 19 micrograms/g. When amino acid levels in cerebral hemispheres, midbrain, pons and medulla, and cerebellum were measured a significant increase in glutamine levels was found in all four regions. Glycine, alanine, serine, threonine, and GABA were significantly reduced in some regions. Caffeine appears to alter some of the metabolic or transport processes regulating amino acid pools in the brain. The decrease of GABA found in pons and medulla may contribute to the observed increase in reflex excitability after caffeine.

Amino Acids↗
PubMed1989

Glycine adjuvant therapy to conventional neuroleptic treatment in schizophrenia: an open-label, pilot study.

In an open-label study, glycine was administered orally (10.8 g/day in three divided doses) to six chronically psychotic patients, as an adjunct to conventional neuroleptic therapy, for periods extending from 4 days to 8 weeks. Glycine was administered in an effort to facilitate endogenous glutamatergic transmission at the level of the N-methyl-D-aspartate (NMDA) receptor complex, since a glutamatergic deficiency in the pathophysiology of schizophrenia has been postulated. Therapeutic efficacy was assessed with standardized psychiatric rating scales. Beneficial effects on behavioral symptomatology were observed in two patients, whereas two others worsened. In one of the two responders, clinical deterioration occurred after glycine withdrawal consistent with a positive adjuvant effect in this patient. However, glycine rechallenge in this patient was not associated with the clinical improvement seen during the initial glycine period. Clinical worsening was not observed after glycine discontinuation in the second responder. Glycine administration reduced neuroleptic-induced muscle stiffness and extrapyramidal dysfunction in three of the six patients. All patients tolerated the clinical trial. The limited penetrability of glycine across the blood-brain barrier is a major limitation of this approach to facilitating glutamatergic transmission at the level of the NMDA receptor complex.

Adjuvants, Pharmaceutic↗
PubMed1987

Depolarization of brain cortex slices and synaptosomes by lithium. Determination of K+-equilibrium potential in cortex slices.

K+-equilibrium potential was determined in brain cortex slices of rat by measuring 86Rb+ distribution between the extra- and intracellular space. The ratio of internal to external Rb+ concentration was 39 +/- 1.8, corresponding to a resting membrane potential of 93.8 mV. Li+ (1-126 mM) decreased the membrane potential in both cortex slices and synaptosomes in a concentration-dependent manner. The presence of 1 mM Li+ was enough to cause a slight but distinct depolarization. During incubation in Li+-containing medium slices took up K+; however, for depolarization the presence of extracellular Li+ seemed to be necessary.

Animals↗
PubMed1987

Nicotine-induced changes in the metabolism of specific brain proteins.

The effect of acute and chronic nicotine on the metabolism of specific brain proteins was examined by measuring incorporation of labeled valine into protein, with densitometric scanning of proteins resolved by gel electrophoresis. Acute and chronic administration of nicotine (0.4 mg/kg per 30 min for 2 hours, s.c., or 0.5 mg/kg per 30 min for 5 days (Alzet mini-pump implanted subcutaneously] reduced incorporation of [14C]valine administered by approximately 6-7%. The results with chronic nicotine administration indicated a lack of tolerance for this effect of nicotine. Mecamylamine, a nicotinic ganglionic antagonist, does not seem to block the inhibition of protein synthesis. Small increases in protein content were observed in a high- and a low-molecular-weight region of SDS-polyacrylamide gel, used to separate proteins from newborn brain. In adult brain after chronic nicotine administration, selective increases and a decrease were seen in selective bands. Results are consonant with selective effects of nicotine on the synthesis or degradation of specific brain proteins.

Animals↗
PubMed1987

The breakdown of the individual neurofilament proteins by cathepsin D.

In a continuing study of proteolysis of CNS proteins by CNS enzymes, neurofilament proteins (210 K, 155 K, 70 K) and desmin were separated, and the breakdown of individual proteins by purified brain cathepsin D was measured and compared to breakdown by plasma thrombin. With both cathepsin D and thrombin, the rate of breakdown of the 70 K protein was the highest, followed by the 155 K, and that of the 210 K was the lowest. With each substrate cathepsin D breakdown was the highest at pH 3; small but significant breakdown could be seen at pH 6. The pattern of intermediate breakdown products depended on pH, with greater amounts of fragments detected at higher pH, and the patterns with the two enzymes were different. We showed that differences exist in cleavage sites and breakdown rates of the neurofilament proteins. The capacity of the cathepsin D present in the tissue to hydrolyze these substrates was high, even at pH close to neutral, and was greatly in excess of that needed for physiological neurofilament turnover.

Animals↗
PubMed1986

Modulation of the serotonin S2-receptor in brain after chronic lithium.

In vivo effects of chronic lithium administration on dopaminergic and serotonergic receptor binding were studied in the striatum and cerebral cortex of the rat. [3H]Domperidone was used as the ligand for the dopaminergic receptor, and [3H]ketanserin for the serotonergic system. Long-term ingestion of lithium (2-3 months) resulted in high levels of lithium in the cerebral cortex and significantly higher potassium levels; the sodium content remained at normal levels. The kinetic constants (Kd and Bmax) of [3H]domperidone binding sites measured in the striatum did not show any deviation from control values, but the receptor concentration (Bmax) of [3H]ketanserin binding sites was significantly reduced in the cerebral cortex of lithium-treated rats. The apparent dissociation constant (Kd) was not changed. The results indicate that the serotonergic component of the [3H]spiperone binding site, which we had previously found to be affected by chronic lithium treatment and which was shown by Peroutka and Snyder to be the 5-HT2 receptor, is selectively affected by lithium.

Animals↗
PubMed1986

Separation and purification of individual neurofilament proteins by reverse-phase high-performance liquid chromatography.

A reverse-phase HPLC method was developed to separate individual neurofilament proteins (210,000, 160,000 and 70,000 Da) from the glial fibrillary acid protein. It is useful for analytical or preparative methods, with yields higher than 80%. The method represents improvement over previous methods in speed, efficiency, and purity. Combining this HPLC method with the conventional chromatographic method on DEAE-cellulose, highly purified individual neurofilament proteins can be obtained in large scale.

Animals↗
PubMed1983

Dietary lithium during development: changes in amino acid levels, ionic content, and [3H]spiperone binding in the brain of rats.

We found that chronic lithium diet affects the sensitivity of neuroleptic receptors and the content of amino acids in the brain, and that the changes in adult animals differ from those in young rats. Pregnant rats were kept on lithium diet (pellets with 0.21% Li2CO3 and 0.21% NaCl) during the gestation period and the offspring were kept on lithium for six weeks after delivery. Control rats were kept on normal diet under identical conditions. In corpus striatum and cerebral cortex of lithium-treated young rats a reduction in apparent dissociation constant and no change in (3H)spiperone total binding sites were found, suggesting a sensitization of the neuroleptic receptor; this result was unlike that obtained with adult lithium-treated rats, where the total number of binding sites was decreased. The lithium content of brain was very high (2.32 meq/kg of wet weight), whereas in the serum only 0.75 meq/l was recorded. K+ and Na+ levels increased by 20% and 9% respectively in the brain and remained at normal levels in the serum. Analysis of free amino acids in the cerebral cortex, midbrain, and cerebellum showed increases in GABA and glycine levels in all three regions, a significant increase in taurine in midbrain, and an increase in lysine in cerebral cortex and cerebellum. The results indicate that the effect of chronic dietary lithium given during pregnancy on the neuroleptic receptor in young rats is different from that in adult animals. It produces an increase in the number of the neuroleptic receptor sites instead of the decline in the number of binding sites found in adult rats. It remains to be established whether this effect is related more to the age of the animal tested or to the stage of development of the CNS at which the lithium was administered.

Amino Acids↗
PubMed1983

Developmental changes in the breakdown of brain tubulin by cerebral cathepsin D.

The activity of cathepsin D on hemoglobin and on cytoplasmic tubulin was measured in brain preparations at different ages--in newborn, 10- and 21-day-old, and young adult rats. Enzyme activity increased after birth, reaching a maximum at around 21 days, and then declined. This increase was not parallel with decreased turnover of proteins during development, but was parallel with decreasing level and increasing microheterogeneity and rate of assembly of tubulin during development. The breakdown of tubulin was heterogeneous, with initial fast breakdown of a large portion, followed by breakdown at a lower rate. This heterogeneity in breakdown persisted throughout development. The breakdown of tubulin, unlike that of hemoglobin, was at all ages greater at pH 5.8 than at pH 3.2. The possible role of cathepsin D in tubulin metabolism and the developmental changes under physiological conditions need further exploration.

Aging↗