Hyphal anastomosis and complementary growth of fused cells inAlternaria alternata

Hyphal anastomosis and complementary growth of fused cells inAlternaria alternata were investigated. Sixty-four experimental isolates were divided into anastomosis-positive (A⁺) and anastomosis-negative (A⁻) groups based on their self-anastomosing ability. Nonself-anastomoses (interisolate) were readily distinguished from self-anastomoses (intraisolate) by using a mixed culture of conidia and hyphal fragments prepared from the respective isolates. Nonself-anastomosis occurred only between the A⁺ isolates irrespective of their pathogenicity and geographic origin. The breakdown of cell walls and the establishment of cytoplasmic continuity between fused cells were microscopically observed only in the self-anastomoses. The frequency of the nonself-anastomosis was, in general, lower than that of the self-anastomosis. For analysis of complementation between the fused cells, mutants doubly marked with auxotrophy and hygromycin B (Hyg) resistance were prepared from wild-type isolates. The identity of the mutants was confirmed by RAPD analysis using three arbitrary primers. Complementary growth occurred only between an A⁺ isolate and its mutant(s) on a minimal medium containing Hyg, demonstrating that the self-anastomoses resulted in perfect cell fusions and the nonself-anastomoses were contact or imperfect fusions.     

Content of Quinolinic Acid and of Other Tryptophan Metabolites Increases in Brain Regions of Rats Used as Experimental Models of Hepatic Encephalopathy

The content of the tryptophan metabolites quinolinic acid (QUIN), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) was measured in various brain areas of rats bearing a portocaval anastomosis (PCA) for 4 weeks, using mass fragmentography or HPLC. In these animals, the content of the excitotoxic compound QUIN increased by 75% in the cortex and 125% in the cerebellum. The content of 5-HT increased by 27% in the brainstem. No changes occurred in other brain areas. On the other hand, the content of 5-HIAA increased by 66% in the cortex, 65% in the caudate, 64% in the hippocampus, 120% in the diencephalon, and 185% in the brainstem. Probenecid administration caused a larger increase of 5-HIAA accumulation in various brain areas of PCA-bearing rats than in those of sham-operated controls. The cortical content of QUIN and 5-HIAA increased after administration of ammonium acetate (7 mmol/kg), whereas an equimolar amount of sodium acetate was inactive. These results confirm that profound changes in the disposition of tryptophan occur in the brains of experimental animals used as models of hepatic encephalopathy. Furthermore, this study adds the excitotoxic compound QUIN to the list of molecules possibly involved in the pathogenesis of this brain disorder.     

Failure of Glucose and Branched-Chain Amino Acids to Normalize Brain Glucose Use in Portacaval Shunted Rats

Several abnormalities in brain and plasma amino acid concentrations caused by portacaval shunting in rats return toward normal after 4 days of intravenous infusion with either glucose or glucose with branched-chain amino acids. To assess the effect of such treatment on brain energy metabolism, regional brain glucose use was measured using [14C]glucose and autoradiography, 5 weeks after portacaval shunting. In one experiment intravenous glucose or glucose with branched-chain amino acids was given for 4 days. In a separate experiment the treatment was given orally for 2 weeks, and in addition to glucose use, brain monoamines and amino acids were measured. No other food was provided; the rats had free access to water. Normally fed shunted rats and sham-operated rats served as controls. Both types of oral treatment lowered the high concentrations of tyrosine, phenylalanine, and glutamine in plasma and brain. Glucose without amino acids normalized brain tryptophan. Levels of brain norepinephrine, 5-hydroxytryptamine (serotonin), and 5-hydroxyindoleacetic acid were significantly raised after shunting. Treatment had no effect on norepinephrine but the glucose diet brought the indoles into the normal range. In contrast, neither intravenous nor oral treatment affected brain glucose use, which remained depressed by 25-30% in all brain areas examined.     

Regional Cerebral Glucose Utilization in Rats with Portacaval Anastomosis

Regional cerebral glucose utilization was measured using [2-¹⁴C]glucose in rats with an end-to-side portacaval anastomosis. The experiments were conducted in two groups of rats 4 to 8 weeks after portacaval shunting was established. One group was paralyzed and given N₂O:O₂ (70:30), whereas the other was conscious, unstressed, and unaware of the experiment. In both groups the rate of glucose utilization was decreased in almost all brain structures by an average of 20% after portacaval shunting. The results showed definitively that cerebral energy metabolism was reduced at a time when there were no obvious neurological abnormalities.     

Uptake of Amino Acids by Brain Microvessels Isolated from Rats after Portacaval Anastomosis

Abstract: The uptake of amino acids by microvessels isolated from brains of rats was studied. Previous studies have demonstrated alterations in blood-brain amino acid transport after portacaval shunt in rats. In order to elucidate whether such changes in the blood-brain barrier were located in the microvessels, brain microvessels were isolated from both rats with portacaval shunt and controls. Brain microvessels from rats 2 weeks after shunt operations took up significantly greater amounts of ¹⁴C-labeled neutral amino acids, but not of glutamic acid. lysine, or α-methylaminoisobutyric acid than microvessels from sham-operated controls. Measurement of uptake kinetics showed a higher V _max for phenylalanine and leucine uptake and a lower V _max for lysine uptake in microvessels from shunted rats compared with control, whereas the respective K _m's of uptake were similar in both preparations. The results suggest that changes in brain microvessel transport activity account for altered brain neutral amino acid concentrations after portacaval shunt and that such changes can be studied in vitro in isolated microvessels.     

Fasciola hepatica: collagen deposition and other histopathology in the rat host's bile duct caused by the parasite and by proline infusion

Bile ducts were examined histochemically to compare the effects of proline infusion with Fasciola hepatica implantation in rats. After 3 weeks of infusion or implantation, both proline and F. hepatica produced increases in the luminal perimeter and collagen content of the bile duct. However, the effect of the parasite was significantly greater than that of proline, and the parasite produced significant increases in the bile duct wall. These results corroborate earlier biochemical and histological studies indicating the important role of proline in the enlargement of the bile duct in fascioliasis.     

改良单层胰肠吻合术在胰十二指肠切除术带蒂大网膜包埋中的应用

目的:探讨带蒂大网膜包埋的改良单层胰肠吻合法重建消化道的胰十二指肠术的临床疗效。方法:回顾性分析2012年9月-2014年12月在我院行胰十二指肠切除术带蒂大网膜包埋改良单层胰肠吻合术的34例患者的临床资料。统计患者的手术时间、胰肠吻合时间、术后出血量、住院时间以及并发症的发生情况。结果:(1)手术平均时间(2.9±1.4)h,胰肠吻合平均时间(14±2.1)min,术后平均出血量(380±60)m L。所有患者经治疗后均治愈出院,住院时间平均(13.0±2.4)天。(2)术后并发症发生率为8例(23.5%),其中胰瘘2例(5.8%),为A级胰瘘;腹部感染3例(8.8%);腹腔出血2例(5.8%);胃排空延迟1例(2.9%)。无手术死亡者,无因严重并发症需要再次手术者。术后病理学诊断胰头癌18例,胆总管下癌8例,壶腹部癌5例,十二指肠乳头癌3例。结论:带蒂大网膜包埋的改良单层胰肠吻合能够减少术后胰瘘、出血、感染等并发症,提高手术成功率,值得临床进一步推广。     

Long-Term Effects of Portacaval Anastomosis on the 5-Hydroxytryptamine, Histamine, and Catecholamine Neurotransmitter Systems in Rat Brain

Abstract: Portacaval anastomosis (PCA) in the rat is used as a model for portal systemic encephalopathy. Changes in the serotonergic, histaminergic, and catecholaminergic neurotransmitter systems are often found shortly after PCA. We have examined the long-term effects of PCA on the aminergic systems in brains of male Wistar rats, which 8 months previously had been subjected to PCA. Precursors, amines, and metabolites were assayed by HPLC. Eight months after PCA, the catecholamine levels were unchanged in all brain regions. In contrast, tryptophan was evenly increased throughout the brain. The accumulation of 5-hydroxytryptophan after decarboxylase inhibition (NSD-1015; 100 mg/kg i.p.) and the endogenous levels of 5-hydroxyindoleacetic acid were significantly higher in PCA rats, particularly in the hypothalamus and midbrain, whereas 5-hydroxytryptamine concentrations were unchanged. Histamine levels were elevated throughout the brain with the greatest increase found in the hypothalamus and in the striatum. tele -Methylhistamine levels were significantly elevated in cortex and hypothalamus. We conclude that 8 months after PCA, catecholaminergic systems had reestablished their homeostasis, whereas serotonergic and histaminergic systems still show profound disturbances in their function. With histamine, this is reflected as an increase in the amounts of both transmitter and metabolite; serotonergic neurons respond by increasing only the level of the metabolite.     

Regional Blood-Brain Barrier Permeability to Amino Acids After Portacaval Anastomosis

Abstract: The influx of phenylalanine, tryptophan, leucine, and lysine across the blood-brain barrier of individual brain structures was studied in rats 7–8 weeks after a portacaval shunt or sham operation. The method involved a brief infusion of labeled amino acid in tracer quantity and quantitative autoradiography. The clearance rates of phenylalanine, tryptophan, and leucine were increased in proportion to each other in every region examined, but not by the same factor. Tryptophan clearance increased the most (about 200%) and leucine the least (about 30%), compared with phenylalanine (about 80%). This was unexpected, as all three amino acids are believed to be transported by the same mechanism. The changes were most marked in several limbic structures and the reticular formation, whereas the hypothalamus was least affected. Plasma clearance of lysine was decreased in all areas by about 70%. Since the circulating lysine concentration was decreased by 13%, the actual rate of lysine influx was even more reduced. The results demonstrate specific alterations in two different amino acid transport systems. The resulting excess brain neutral amino acids, some of which are neurotransmitter precursors, as well as reduced basic amino acid availability, may be of etiological significance in hepatic encephalopathy.