Cortical hypometabolism in injured brain: New correlations with the noradrenergic and serotonergic systems and with behavioral deficits

Changes with time after injury in behavioral deficits, as determined by the Morris swim test, and the in vivo specific binding of HEAT, a selective ₁-adrenoreceptor ligand, were compared with the time-course of development of cortical hypometabolism in rats with focal freezing lesions. In our trauma model, cortical hypometabolism was detectable in the lesioned hemisphere at 4 hr, became maximal (50% of normal) at 3 days and diminished towards normal on days 5 and 10 post-injury. Progressive impairment of acquisition of the Morris water maze task was demonstrated up to day 3 post-lesion with improvement thereafter. On day 3 the latency to reach criterion was 60% longer in lesioned animals than in corresponding sham-operated ones. An increase in the volume of distribution of HEAT, limited to cortical areas of the lesioned hemisphere, was demonstrable at 4 hr post-lesion and reached its maximum on day 3 (200% of normal) with subsequent return toward normal on days 5 and 10. Several types of drugs were shown previously to modify the cortical hypometabolism associated with cerebral injury. The present data indicate that the same drugs also modify the in vivo binding of HEAT and the behavioral deficits induced by brain lesions. Ibuprofen, a non-steroidal anti-inflammatory drug, p-chlorophenylalanine, an inhibitor of serotonin synthesis, ketanserin, a specific 5HT₂-receptor antagonist, and prazosin, an ₁-adrenergic receptor blocker all normalized the in vivo binding of HEAT in the cortical areas of the lesioned hemisphere. All groups of animals treated with these drugs also showed subtle, but statistically highly significant improvements in latency to locate the platform in the Morris water maze. Taken together these results show good correlation between behavioral deficits, changes in ₁-noradrenergic receptor binding and cortical hypometabolism in injured brain. This supports the hypothesis that post-injury cortical hypometabolism is a reflection of cortical functional depression in which both the serotonergic and noradrenergic neurotransmitter systems play a role, compatible with their inhibitory effects in the cortex and their postulated involvement in cortical information processing.Special issue dedicated to Dr. Leon S. Wolfe.     

Effective cryoprotection of thylakoid membranes by ATP

Freezing of isolated spinach thylakoids in the presence of NaCl uncoupled photophosphorylation from electron flow and increased the permeability of the membranes to protons. Addition of ATP prior to freezing diminished membrane inactivation. On a molar basis, ATP was at least 100 times more effective in protecting thylakoids from freezing damage than low-molecularweight carbohydrates such as sucrose and glucose. The cryoprotective effectiveness of ATP was increased by Mg²⁺. In the absence of carbohydrates, preservation of thylakoids during freezing in 100 mM NaCl was saturated at about 1–2 mM ATP, but under these conditions membranes were not fully protected. However, in the presence of small amounts of sugars which did not significantly prevent thylakoid inactivation during freezing, ATP concentrations considerably lower than 0.5 mM caused nearly complete membrane protection. Neither ADP nor AMP could substitute for ATP. These findings indicate that cryoprotection by ATP cannot be explained by a colligative mechanism. It is suggested that ATP acts on the chloroplast coupling factor, either by modifying its conformation or by preventing its release from the membranes. The results are discussed in regard to freezing injury and resistance in vivo.Abbreviations CF₁ chloroplast coupling factor - Hepes 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - PMS phenazine methosulfate - Tris 2-amino-2-(hydroxymethyl)-1,3-propandiol     

Studies on the damage to Escherichia coli cell membrane caused by different rates of freeze-thawing

Freeze-thawing of Escherichia coli cells caused a release of cell membrane components such as protein, phospholipids and lipopolysaccharides. A greater amount of release and a lesser extent of cell survival were seen in slow freeze-thawing than in rapid freeze-thawing. Several dehydrogenases in the cells were also freed. The mode of release was also dependent on the rate of freeze-thawing.The materials released by slow freeze-thawing were found to be mostly composed of outer membrane components, whereas the materials released by rapid freeze-thawing contained cytoplasmic as well as outer membrane components. The chemical composition of these fragments differed significantly from that of the original membranes. The relative content of cytoplasmic membrane-bound enzymes in these fragments also differed from that of the cytoplasmic membrane.The fragmentation was assumed to have resulted mainly from the crystallization of external water. In slow freeze-thawing, it was considered that the phase separation of the membrane phospholipid bilayer increased the possibility of outer membrane fragmentation. Rapid freeze-thawing caused cytoplasmic membrane damage to the cells as well as to the outer membrane. In rapid freeze-thawing, the effect of phase separation appeared to be small because of rapid passage through the transition temperatures.The presence of 10% glycerol completely inhibited the release of cellular materials and enzymes. Cell survival was maintained at a high level in the glycerol-treated samples whether freeze-thawed slowly or rapidly.     

Effects of chilling on tomato fruit texture

The effects of chilling on tomato ( Lycopersicon esculentum Mill cv. Caruso) texture were investigated using fruit stored at 22°C (nonchilled) or 5°C (chilled) for 28 days. or at 5°C for 15 days before transfer to 22°C to facilitate ripening during and additional 13 days (prechilled). Prechilled fruit exhibited symptoms of slight chilling injury, i.e. development of mealiness, accelerated softening relative to that of nonchilled fruit and nonuniform surface colour development. The firmness of all fruit decreased during ripening and chilled storage when measured by flat plate compression and puncture, especially during the early stages of ripening of nonchilled and prechilled fruit. The compression firmness of pericarp tissue similarly decreased during ripening of nonchilled and prechilled fruit, but was maintained during chilling. Total moisture content (ca 94%) of tissue, uronide content (32-35% w/w) and extracted β-galactosidase activity did not differ significantly ( P > 0.05) among fruit during ripening and chilled storage. The degree of uronide methyl esterification in ethanol-insoluble solids prepared from pericarp tissue (EIS) was relatively low for all fruit. i.e. <40%. EIS from which greater levels of pectinesterase were extracted (i.e. nonchilled>chilled>prechilled) exhibited decreased levels of uronide methyl esterification. Markedly elevated levels of β-glucosidase activity were extracted from prechilled EIS. Total polygalacturonase activity (mainly as PGI) and autolysis of enzyme-extracted EIS were inversely correlated ( P ≤ 0.05) only with the loss of nonchilled fruit and tissue firmness and prechilled fruit firmness. Results suggest a possible role for β-glucosidase in textural changes of prechilled fruit and tissue (e.g. loss of firmness, development of mealiness) and also implicate loss of skin strength in the softening of whole fruit during chilling.     

Mechanisms towards compensation of long-term haemopoietic injury in mice after 5 Gy irradiation:In vivo andin vitro enhancement of superoxide anion production by granulocytes

This paper analyzes the long-term (6 and 12 months) function of mouse granulocytes after total body irradiation with a single dose (5 Gy) of X-rays. Superoxide anion production has been investigated in granulocytes from peripheral blood, and also in those harvested from long term bone marrow cultures, with the aim of correlating the environmental damage induced by radiation with the functional properties of granulocytes. Anin vivo andin vitro enhancement of superoxide anion production and protein levels in granulocytes from irradiated mice is described. The presence of some colony stimulating factor in the supernatant of cultures from irradiated mice could play an important role in the priming of granulocytes.     

Breakup and re-formation of colony in the first-instar larvae of the winter cherry bug,Acanthocoris sordidus thunberg (Hemiptera: Coreidae), in relation to the defence against their enemies

The winter cherry bug, Acanthocoris sordidusThunberg , lives in aggregation especially in their early larval instars. Using the 1st-instar larvae of this species, the author tried to clarify both the processes and the mechanisms of the breakup and later re-formation of colony in relation to the defence against their enemies. The results obtained were summarized as follows.

1. In the field population, there is a high possibility of dispersal of the 1st-instar larvae from a colony possibly through the disturbance by some predators but they can re-form a colony with each other or join, with colonies of different instar larvae.
2. The individuals in a colony immediately disperse through the attack of predatory coccinellid beetle, Harmonica axyridis but tend to re-form a colony in a short time.
3. The breakup of colony is caused by the secretion from the attacked individual.
4. The formation of colony is attributed to the habit closely related with the senses of smell and/or contact.

From these results, it was concluded that the dispersal of 1st-instar larvae from a colony, followed by the re-formation of a colony, is an an adaptive behaviour to escape from the attack by their predators.     

Putative therapeutic impacts of cardiac CTRP9 in ischaemia/reperfusion injury

Recently, cytokines belonging to C1q/tumour necrosis factor‐related proteins (CTRPs) superfamily have attracted increasing attention due to multiple metabolic functions and desirable anti‐inflammatory effects. These various molecular effectors exhibit key roles upon the onset of cardiovascular diseases, making them novel adipo/cardiokines. This review article aimed to highlight recent findings correlated with therapeutic effects and additional mechanisms specific to the CTRP9, particularly in cardiac ischaemia/reperfusion injury (IRI). Besides, the network of the CTPR9 signalling pathway and its possible relationship with IRI were discussed. Together, the discovery of all involved underlying mechanisms could shed light to alleviate the pathological sequelae after the occurrence of IRI.