Comparison of Effects of Sublethal Microwave Radiation and Conventional Heating on the Metabolic Activity of Staphylococcus aureus

This study was conducted in an attempt to characterize some of the effects of sublethal microwave radiation on cells of Staphylococcus aureus. Cultures were exposed to microwave radiation for 10, 20, 30, and 40 s. The effects of a conventional heat treatment were also compared by placing flasks containing cultures in a boiling water bath for the amount of time required to reach temperatures equivalent to those found in cultures exposed to microwave radiation. Control, microwave-treated, and conventionally heat-treated cultures were centrifuged, pellets were resuspended in distilled water, and the resulting suspensions were passed through a French pressure cell. Cell lysates and walls were then isolated and assayed for enzymatic activity. Thermonuclease production was also determined at various levels of exposure of cells to microwave radiation. Activities of malate and α-ketoglutarate dehydrogenases, cytochrome oxidase, and cytoplasmic adenosine triphosphatase were higher in microwave-treated cells than in control cells. Membrane adenosine triphosphatase, alkaline phosphatase, and lactate dehydrogenase activities were unaffected when cells were exposed to microwave radiation. The activity of glucose-6-phosphate dehydrogenase was decreased by exposure of cells to microwave radiation. In conventionally heated cells, activities of glucose-6-phosphate and malate dehydrogenases and cytoplasmic adenosine triphosphatase increased activities of α-ketoglutarate and lactate dehydrogenases decreased, and alkaline phosphatase activity remained unaffected. Increased levels of thermonuclease activity were observed when cells were exposed to microwave radiation for 10 or 20 s. Data indicate that microwave radiation affects S. aureus in a manner which cannot be explained solely by thermal effects.     

Quantitative enzyme histochemistry of rat foetal brain and trigeminal ganglion

Summary The increasing concern and the efforts in determining neurological effects in offsprings resulting from maternal exposure to xenobiotics are faced with several difficulties in monitoring damage to the central nervous system. In this paper, the efficiency of several enzyme histochemical reactions for analysing the forebrain and the trigeminal ganglia of rat foetuses are reported. Brains of 20-day-old Sprague-Dawley rat foetuses were frozen and analysed for 18 enzymes that had previously been used to monitor initial injury caused by toxic compounds in liver and other organs. Eight enzymes appeared suitable as histochemical markers for the functional integrity of different areas in brain and ganglia of rats exposed to xenobiotics. They were lactate, malate, glycerophosphate (NAD-linked), succinate, aldehyde and glucose 6-phosphate dehydrogenases, -glycerophosphate-menadione oxidoreductase and cytochromec oxidase. The activities of the enzymes were determined by microphotometry and the arrangement of absorbances of the enzyme final reaction products into appropriate analytical tables is proposed as an efficient procedure for data analysis.Abbreviations AcChE acetylcholinesterase - AldDH aldehyde dehydrogenase - ALKPase alkaline phosphatase - 5AMPase adenosine monophosphatase - ATPase Mg²⁺ dependent adenosine triphosphatase - CytOx cytochromec oxidase - GAPDH glyceraldehyde phosphate dehydrogenase - GIDH glutamate dehydrogenase - GLPDH glycerophosphate: NAD oxidoreductase - CPODH glycerophosphate:menadione oxidoreductase - G6Pase glucose-6-phosphatase - G6PDH glucose-6-phosphate dehydrogenase - IDH lactate dehydrogenase - MaDH malate dehydrogenase - MAO monoamine oxidase - NADPH, DH, NADPH tetrazolium oxidoreductase - SuDH succinate dehydrogenase - 6PGDH 6-phosphogluconate dehydrogenase     

The enzyme histochemistry of developing odontoblasts in cattle, pigs and horses

Synopsis The histochemical distribution of some hydrolytic and oxidative enzymes in developing odontoblasts and subodontoblasts in cattle, pigs and horses has been observed in cryostat sections of teeth that have been decalcified with neutral EDTA.Undifferentiated dental epithelium and immature odontoblasts of the bell stage tooth germ showed lower levels of enzymatic activity as compared with the well-developed tooth germ.When the dentine matrix began to form, the young odontoblasts appeared to have a significantly positive reaction for acid phosphatase, and gradually other enzymes developed an activity at the top of the cusp.Odontoblasts as well as subodontoblastic-rich cells showed strong enzymatic activities for hydrolytic and oxidative enzymes, that is, they were strongly reactive for alkaline and acid phosphatase and lactate and malate dehydrogenases, and moderately reactive for other oxidative enzyme systems.It is suggested that the subodontoblastic layer is concerned with the biosynthesis of dentinal matrix as well as with the odontoblasts themselves.     

Enzyme histochemical studies on rat lungs 2. Normal enzyme distribution in the alveolar tissue of the mature lung

Synopsis The activity and distribution of the following eighteen oxidative and hydrolytic enzyme systems have been investigated in the lung of the adult rat: reduced NAD dehydrogenase, reduced NADP dehydrogenase, succinate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, glucose dehydrogenase, glutamate dehydrogenase, -hydroxybutyrate dehydrogenase, acid phosphatase, alkaline phosphatase, glucose-6-phosphatase, adenosine triphosphatase, 5-nucleotidase, non-specific esterase, cytochrome oxidase and -glucuronidase.The low concentration of cells in sections of inflated lung may have made histochemical demonstration of some enzymes impossible because the enzyme concentration was below that detectable by the method employed.The carboxylic acid cycle and the hexose monophosphate shunt were potentially active but fatty acid metabolism was not indicated.The granular reaction sometimes encountered in alveolar cell cytoplasm may be useful for differentiating alveolar cell types, but further cytochemical studies are required to resolve the possible metabolic differences of alveolar cells.     

Semipermeable membranes for improving the histochemical demonstration of enzyme activities in tissue sections. V. Isocitrate: NADP+ oxidoreductase (decarboxylating) and malate: NADP+ oxidoreductase (decarboxylating).

Improved histochemical techniques for the demonstration of NADP+-specific isocitrate dehydrogenase and malate dehydrogenase in tissue sections are described. With these techniques a semipermeable membrane is interposed between the incubating solutions and the tissue sections preventing diffusion of enzymes into the medium during incubation. In the histochemical system the NADP+-dependent enzymes catalyze the electron transfer from threo-Ds-isocitrate or L-malate into NADP+. Phenazine methosulphate and menadione serve as intermediate electron acceptors between reduced coenzyme and nitro-BT. Sodium-azide and amytal are incorporated into the incubating-medium to block electron transfer to the cytochromes. For demonstrating enzyme activities in sections containing non-specific alkaline phosphatase, a phosphatase inhibitor is added into the incubation media. Problems involved in the histochemical demonstration of both enzymes are discussed.     

Cultured human fibroblast enzymes. III. Enzyme activity in a triploid strain]

Complex investigation of 5 enzymes was carried out in a cell strain with triploidy 69, XXY, derived from a human spontaneous abortus. The activity of 3 enzymes (acid phosphatase, lactate and malate dehydrogenases) in triploid cells proved to be significantly increased as compared to those of 3 diploid strains, whereas the activity of alkaline phosphatase was decreased. The activity of glutamate-oxalacetate transaminase did not change. The absence of the pronounced genetic dose effect and different alteration of the activities of the enzymes studied may be considered as an expression of a disbalance of enzymes in cytogenetically defective cells.     

Histochemical observations on the exoerythrocytic malaria parasite Plasmodium berghei in rat liver

Summary Enzyme histochemical methods were performed on sporozoite infected liver tissue of rats in order to gain insight into the nutrition and metabolism of exoerythrocytic forms of Plasmodium berghei. The following enzymes were demonstrated in the hepatocytic stages of the parasites, obtained 41 and 48 h after inoculation of sporozoites: acid phosphatase, cytochrome oxidase, NADH-tetrazolium reductase, succinate dehydrogenase, NAD⁺ and NADP⁺ dependent isocitrate dehydrogenase, NADP⁺-dependent malate dehydrogenase, lactate dehydrogenases, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenases and -glycerol-phosphate dehydrogenase. The results suggest that a conventional Embden-Meyerhoff pathway, pentose phosphate pathway and Krebs' citric acid cycle may in part be present in these exoerythrocytic parasites. Alkaline phosphatase, nucleoside polyphosphatase, 5nucleotidase. glucose-6-phosphatase, -glucan phosphorylase, NAD⁺ dependent malate dehydrogenase, amino-peptidase M and non-specific esterases were not detected by our techniques in the parasite. The enzyme distribution of this intrahepatocytic malaria parasite revealed by histochemistry is compared with the enzyme distribution in the other phases of the parasite's life cycle.This study was made possible by grants from the Jan Dekker Foundation for Biomedical Research and the Niels Stensen Foundation, The Netherlands, to the first author     

Histochemical observations on the exoerythrocytic malaria parasite Plasmodium berghei in rat liver

Enzyme histochemical methods were performed on sporozoite infected liver tissue of rats in order to gain insight into the nutrition and metabolism of exoerythrocytic forms of Plasmodium berghei. The following enzymes were demonstrated in the hepatocytic stages of the parasites, obtained 41 and 48 h after inoculation of sporozoites: acid phosphatase, cytochrome oxidase, NADH-tetrazolium reductase, succinate dehydrogenase, NAD+ and NADP+ dependent isocitrate dehydrogenase, NADP+-dependent malate dehydrogenase, lactate dehydrogenases, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenases and alpha-glycerol-phosphate dehydrogenase. The results suggest that a conventional Embden-Meyerhoff pathway, pentose phosphate pathway and Krebs' citric acid cycle may in part be present in these exoerythrocytic parasites. Alkaline phosphatase, nucleoside polyphosphatase, 5' nucleotidase, glucose-6-phosphatase, alpha-glucan phosphorylase, NAD+ dependent malate dehydrogenase, amino-peptidase M and non-specific esterases were not detected by our techniques in the parasite. The enzyme distribution of this intrahepatocytic malaria parasite revealed by histochemistry is compared with the enzyme distribution in the other phases of the parasite's life cycle.     

Enzyme histochemistry of the sheep uterus during the oestrous cycle

Enzyme histochemical techniques were applied to frozen sheep uteri from different stages of the oestrous cycle. The localization and activities of succinate, lactate, glucose-6-phosphate, and isocitrate (NADP+) dehydrogenases and acid and alkaline phosphatases were studied in the luminal and glandular epithelia, caruncle and myometrium. Enzyme activity in the sections was scored on a scale of 0--5. In general the enzyme activity in the uterine caruncles and epithelia was higher than in the myometrium. The myometrium did not show any alkaline phosphatase activity and isocitrate dehydrogenase (NADP+) activity was negligible. The low activities of acid phosphatase and lactate dehydrogenase and the moderate levels of glucose-6-phosphate and succinate dehydrogenases in the myometrium were constant. The caruncular tissue showed high levels of phosphatases and glucose-6-phosphate dehydrogenase, moderate levels of lactate and succinate dehydrogenases, and low levels of isocitrate dehydrogenase (NADP+) throughout the oestrous cycle. Much lower phosphatase and isocitrate dehydrogenase (NADP+) levels were found in the epithelium of deep glands compared with superficial glands. The high activity of acid and alkaline phosphatases in the luminal epithelium and the superficial glands was constant from mid-cycle to ovulation, but a significant decrease was observed immediately after ovulation. The level of dehydrogenases in epithelia was generally high and did not change during the oestrous cycle.     

Role of DL α-lipoic acid in gentamicin induced nephrotoxicity

The effect of DL -lipoic acid on the nephrotoxic potential of gentamicin was examined. Intraperitoneal injection of gentamicin (100 mg/kg/day) to rats resulted in decreased activity of the glycolytic enzymes-hexokinase, phosphoglucoisomerase, aldolase and lactate dehydrogenase. The two gluconeogenic enzymes—glucose-6-phosphatase and fructose-1, 6-diphosphatase, the transmembrane enzymes namely the Na⁺, K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase and the brushborder enzyme alkaline phosphatase, also showed decreased activities. This decrease in the activities of ATPases and alkaline phosphatase suggests basolateral and brush border membrane damage. Decreased activity of the TCA cycle enzymes isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH), suggests a loss in mitochondrial integrity. These biochemical disturbances were effectively counteracted by lipoic acid administration. Lipoic acid administration by gastric intubation at two different concentrations (10 mg and 25 mg/kg/day) brought about an increase in the activity of the glycolytic enzymes, ATPases and the TCA cycle enzymes. The gluconeogenic enzymes however showed a further decrease in their activities at both the concentrations of lipoic acid administered. These observations shed light on the nephroprotective action of lipoic acid against experimental aminoglycoside toxicity and the protection afforded at 25 mg/kg/day of lipoic acid was noted to be higher than that at 10 mg level.     

The influence of lipoic acid on adriamycin induced nephrotoxicity in rats

Adriamycin, which is widely used in the treatment of various neoplastic conditions, exerts toxic effects in several organs. Adriamycin nephrotoxicity has been recently documented in a variety of animal species. The present study was designed to investigate the effect of lipoic acid on the nephrotoxic potential of adriamycin. The study was carried out with adult male albino rats of Wistar strain. Test animals were divided into four groups of six rats each as follows: Group I (control) received only normal saline throughout the course of the experiment. Group II (ADR) received intravenous injections of adriamycin through the tail vein (1 mg kg^–1 body wt day^–1) once a week for a period of 12 weeks. Group III (LA) received lipoic acid (35 mg kg^–1 body wt day^–1) intraperitoneally once a week for a period of 12 weeks. Group IV (ADR + LA) received a single injection of lipoic acid intraperitoneally 24 h prior to the administration of adriamycin through the tail vein once a week for a period of 12 weeks. Intravenous injections of adriamycin resulted in decreased activities of the glycolytic enzymes; hexokinase, phosphoglucoisomerase, aldolase and lactate dehydrogenase in the rat renal tissue. The gluconeogenic enzymes; glucose-6-phosphatase and fructose-1,6-diphosphatase, showed a decline in their activities on adriamycin administration. The transmembrane enzymes namely the Na⁺,K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase and the brush-border enzyme alkaline phosphatase also showed a decrease in their activities. This decrease in the activities of ATPases and alkaline phosphatase suggests basolateral and brush-border membrane damage. Decreased activities of the TCA cycle enzymes isocitrate dehydrogenase, succinate dehydrogenase and malate dehydrogenase, suggest a loss in mitochondrial function and integrity. Nephrotoxicity was evident from the increased excretions of N-acetyl--D-glucosaminidase and -glutamyl transferase in the urine of adriamycin administered rats. These biochemical disturbances were effectively counteracted on pretreatment with lipoic acid, which brought about an increase in the activities of glycolytic enzymes, ATPases and the TCA cycle enzymes. On the other hand, the gluconeogenic enzymes showed a further decrease in their activities on lipoic acid pretreatment. LA pretreatment also restored the activities of the urinary enzymes to normal. These observations shed light on the nephroprotective action of lipoic acid rendered against experimental aminoglycoside toxicity.     

Survey of isoenzymes in the snail Cepaea nemoralis using different buffer/gel systems in polyacrylamide disc gel electrophoresis: Validity of comparisons and effect of “Nothing dehydrogenase” activity

An investigation into isoenzymic analysis using four different buffer/gel systems was carried out. Fourteen different isoenzyme systems were surveyed on each buffer/gel system. It is shown that comparable results are not obtained between different systems. Previous workers in Cepaea nemoralis have used different buffer/gel systems from one another. Alkaline phosphatase and acid phosphatase and certain lactate and malate dehydrogenases are shown to behave similarly in three different systems. It is tentatively suggested that these isoenzymes may be genetically identical. Nothing dehydrogenase activity is demonstrated in gels stained for other dehydrogenases. It is suggested that nothing dehydrogenase activity may be attributable to glutamate or malate dehydrogenase.This work was supported by the Science Research Council.     

Quantitative aspects of enzyme histochemistry on sections of freeze-substituted glycol methacrylate-embedded rat liver

Freeze-substituted rat liver embedded in glycol methacrylate (GMA) has been used to demonstrate the activities of several enzymes. The following enzymes could be detected in GMA-sections by the indicated histochemical procedure(s): 5-nucleotidase (lead salt, cerium-diaminobenzidine), alkaline phosphatase (indoxyl-tetrazolium salt), catalase (diaminobenzidine), acid phosphatase (diazonium salt), lactate dehydrogenase (tetrazolium salt) and glutamate dehydrogenase (tetrazolium salt). The activities of all these enzymes were dramatically decreased compared with the activities demonstrated in unfixed cryostat sections, with the exception of catalase. The activities of the following enzymes could not be detected in GMA-sections: glucose-6-phosphate dehydrogenase (tetrazolium salt), xanthine oxidoreductase (tetrazolium salt), d-amino acid oxidase (cerium-diaminobenzidine-cobalt-hydrogen peroxide) and glucose-6-phosphatase (cerium-diaminobenzidine). The possible role of restricted penetration of reagents into the resin was studied by measuring cytophotometrically the enzyme activities in GMA-sections of 3 and 6 m in thickness. For all the enzymes that could be detected, the 6 m : 3 m ratio varied from 1.4 to 2.7. An eventual retarded penetration of reagents into the resin was investigated by measuring cytophotometrically the amount of final reaction product during incubation for acid phosphatase and glutamate dehydrogenase activities. In both cases linear relationships without a lag phase were found for the specific enzyme activities with incubation time. Chemical denaturation of proteins or masking of active sites in proteins due to embedding in the resin monomer may be considered to be the main cause of decreased enzyme activities.     

Enzyme histochemical properties of kitten osteoclasts in bone imprint preparations

Synopsis The enzyme histochemical characteristics of osteoclasts in imprints of the metaphyseal regions of femurs, from male kittens aged approximately 18 weeks, were investigated. A selected number of enzymes representative of a variety of metabolic pathways were studied. The enzyme profile, time for the first appearance of detectable reaction product, intensity of the reactions, and localization of the reaction products were noted.Osteoclasts are rich in enzymes, and metabolic pathways are well developed in respect of the utilization of the reduced coenzymes NADP and NADPH, succinic, malic, lactic, and isocitric acids, -hydroxybutyrate and glucose-6-phosphate, the reactions being mediated by the diaphorases and dehydrogenases. The activities of acid and neutral phosphatases, non-specific esterases, and leucine naphthylamidase were high in these cells. However, little or no activity was demonstrated in respect of glutamate and -glycerophosphate dehydrogenases or of aryl sulphatase, glucose-6-phosphatase and alkaline phosphatase.     

Histochemistry of implantation in the rabbit

Summary The distribution of glycogen, acid and neutral mucopolysaccharides, hydrolases alkaline phosphatases, and carbohydrate dehydrogenases is described in the rabbit blastocyst and its surroundings over the implantation period from 5 to 9 days.Glycogen is found mainly in the embryonic tissues, where peaks of concentration coincide with differentiation, some is also seen in the uterine epithelium and secretion, and large quantities accumulate in the developing decidua.Neutral mucopolysaccharide is found in the yolk-sac and embryonic endoderm, and as secretion droplets in the uterine epithelium and secretion.Acid mucopolysaccharide occurs in the embryonic coverings and uterine secretion.RNA is associated in the embryo with developing tissues, and accumulates in the developing decidual cells.Hydrolases (acid phosphatase, and B esterase) increase their activity in the trophoblast knobs, in developing syncytiotrophoblast, and in the embryonic endoderm. Degeneration of the uterine epithelium is associated with maximal hydrolase activity.Trophoblastic alkaline phosphatase activity (non-specific and specific) decreases from 5 to 7 days of gestation, then increases markedly in the developing syncytiotrophoblast. AMPase appears in the embryonic mesoderm. In the uterine epithelium intense brush border staining is seen, and TPPase and UDPase become visible for a short period in the Golgi region. Phosphatases increase their activity in the decidua to 8 days and then decrease.Carbohydrate dehydrogenases (except -glycero-phosphate and -hydroxy-butyrate dehydrogenases) increase their activity in embryonic tissues, particularly in the developing syncytiotrophoblast and endoderm. Symplasma formation in the uterine epithelium is also associated with increase in enzyme activity, and a similar increase, up to 8 days of gestation, is seen in the decidua with isocitrate, malate, glucose-6-phosphate, lactate, succinate, and furfuryl alcohol dehydrogenases.Some correlation is found between the histochemical findings and the phenomena of epithelial removal, uterine secretion, decidual formation and function, giant cell function, morphogenesis, and histiotrophic nutrition, and the results are compared with previous findings for the rat in which implantation is morphologically, and probably physiologically a very different process.     

The influence of freezing and freeze-drying of tissue specimens on enzyme activity

Summary In the presented study the influence of freezing and freeze-drying on enzyme activity is described. Attention is paid to 16 enzymes which can be used for quantitative enzyme histochemical techniques.With the exception of succinate dehydrogenase only, no significant inactivation during freezing and freeze-drying procedures could be demonstrated with lactate dehydrogenase, malate dehydrogenase (NAD⁺), malate dehydrogenase (decarboxylating) (NADP⁺), isocitrate dehydrogenase (NADP⁺), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, NADH-oxydoreductase, mitochondrial glycerol-3-phosphate dehydrogenase, cytochrome c oxidase, phosphoglucomutase, glucosephosphate isomerase, glucose-6-phosphatase, acid phosphatase, -glucuronidase and non specific aryl esterase. Therefore the results supply a sound foundation for those quantitative enzyme histochemical techniques in which tissue specimens are frozen or frozen-dried before enzyme estimations are performed.     

Characterization of Enterobacter cloacae and E. sakazakii by electrophoretic polymorphism of acid phosphatase, esterases, and glutamate, lactate and malate dehydrogenases

Acid phosphatase, esterases, and glutamate, lactate and malate dehydrogenases of 34 strains of Enterobacter cloacae and 22 strains of Enterobacter sakazakii were analysed by horizontal polyacrylamide agarose gel electrophoresis and by isoelectrofocusing in thin-layer polyacrylamide gel. The two species could be separated on the basis of distinct electrophoretic patterns of all enzymes analysed. Glutamate dehydrogenase and acid phosphatase were detected exclusively in E. cloacae, whereas esterase bands were more intensively stained in E. sakazakii. For each species, two zymotypes could be distinguished, on the basis of electrophoretic mobilities of malate dehydrogenase and banding patterns of esterase for E. cloacae, and by both isoelectric point and electrophoretic mobilities of an esterase and of lactate and malate dehydrogenases for E. sakazakii. The high degree of enzyme polymorphism within the two species permitted precise identification of strains. The variations in electrophoretic patterns might therefore provide useful epidemiological markers.     

The effect of sodium ethylenediaminetetra-acetate (na2 edta) on the histochemical demonstration of some enzyme activities in neonatal mouse molar tissues

Summary Décalcification of neonatal mouse tissues, including the first molar germs, by 10 per cent ethylenediaminetetra-acetate (Na₂EDTA) containing 7.5 per cent polyvinylpyrrolidone (PVP) was found to increase the histochemical reactions of lactate and malate dehydrogenase activities, as compared with non-decalcified preparations. The activity of glucose-6-phosphate dehydrogenase was not significantly affected by the demineralization procedure. Adenosinetriphosphatases (ATPases) in the endothelial cells and in the nuclei of most of the cells in the cryostat sections (8 ) showed enhanced activities after the EDTA-treatment (48 hours at 4° C). ATPase in matrix-forming odontoblasts and ameloblasts, however, was consistently inhibited.The biochemical test indicated that the EDTA- and PVP-solutions, according to Fullmer (1966), allowed only a trace amount of protein leakage into the decalcification fluid.Preservation and retention of protein molecules and a simultaneous removal of contaminating ions and de-masking of active sites of the enzymes might be responsible for some of the effects observed in enzyme histochemical registrations.     

Microwave-stimulated brain enzyme incubations are possible at the unphysiological condition of 50 degrees C

Microwave-stimulated enzyme incubations for acetylcholinesterase, 5'-nucleotidase, alkaline phosphatase, lactate dehydrogenase, malate dehydrogenase, succinic dehydrogenase and isocitric dehydrogenase were studied, and compared with incubations in a waterbath. Temperature settings of 37 degrees C and 50 degrees C were used, and the incubation times were varied from 30 seconds to 30 minutes. The desired temperature of the incubation solution was reached in the microwave oven within 1 minute, whilst in the waterbath it took 10 to 25 minutes. The microscopic results for alkaline phosphatase and succinic dehydrogenase at a temperature setting of 50 degrees C were superior in the microwave method for incubation times less than 15 minutes. It is postulated that the increased reaction product of alkaline phosphatase and succinic dehydrogenase is due to a temperature effect, which has to be large enough to be of practical value. For the other enzymes studied, microwave-stimulated incubations were no better than the conventional incubations at corresponding temperatures. For 5'-nucleotidase there were aspecific lead deposits in the microwave method. All enzymes performed at the elevated, unphysiological temperature of 50 degrees C proved to have advantages, except for 5'-nucleotidase, whilst for malate dehydrogenase there was an aspecific reduction of the colour developer at this temperature.     

Experimental protein malnutrition in primates: Cytochemical studies on the cerebellum of the squirrel monkey,Saimiri Sciureus

Synopsis The cerebellum of healthy and malnourished squirrel monkeys was studied histopathologically and cytochemically for a number of important enzymes such as phosphatases (acid and alkaline phosphatase, ATPase, thiamine pyrophosphatase), esterases (simple esterase and acetylcholinesterase), dehydrogenases (succinate, malate and isocitrate dehydrogenase, lactate dehydrogenase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase), monoamine oxidase and phosphorylase. The Purkinje cells, stellate and basket cells were found to be more sensitive to protein malnutrition compared to the other types of cells in the cerebellum. An increase in the number of dark cells with large amounts of ribonucleoprotein complex in the Purkinje cell layer of the extremely malnourished animals sacrificed after 15 weeks on a low protein diet may be significant and may reflect either an abnormal metabolic process or an interruption in the axonal transport of RNA complex. This may also be directly related to a significant reduction in the level of oxidative enzymes, especially those of the tricarboxylic acid cycle, these being the main source of energy stored in ATP. At the same time the level of lysosomal enzymes, which are responsible for the catalysis of the different degradation reactions, is greatly increased and indicates cellular catabolism. The present investigations point to the probability that the neurons adapt to the changed environment by beginning to utilize structural proteins for their basic metabolism.