[The development of a fluid percussion device for brain injury of animals]

This paper discusses a fluid percussion device for brain injury. The injury is produced by striking the cork with a pendulum dropped from a known fall height to produce transient high pressure through a fluid transfer system. Experimental results show the device has the advantages of making a controllable, repeatable, and precise injury, and it can produce different levels of injury on different animals.

The zebrafish gene cloche acts upstream of a flk-1 homologue to regulate endothelial cell differentiation

The zebrafish cloche mutation affects both the endothelial and hematopoietic lineages at a very early stage (Stainier, D. Y. R., Weinstein, B. M., Detrich, H. W., Zon, L. I. and Fishman, M. C. (1995). Development 121, 3141–3150). The most striking vascular phenotype is the absence of endocardial cells from the heart. Microscopic examination of mutant embryos reveals the presence of endothelial-like cells in the lower trunk and tail regions while head vessels appear to be missing, indicating a molecular diversification of the endothelial lineage. Cell transplantation experiments show that cloche acts cell-autonomously within the endothelial lineage. To analyze further the role of cloche in regulating endothelial cell differentiation, we have examined the expression of flk-1 and tie, two receptor tyrosine kinase genes expressed early and sequentially in the endothelial lineage. In wild-type fish, flk-1-positive cells are found throughout the embryo and differentiate to form the nascent vasculature. In cloche mutants, flk-1-positive cells are found only in the lower trunk and tail regions, and this expression is delayed as compared to wild-type. Unlike the flk-1-positive cells in wild-type embryos, those in cloche mutants do not go on to express tie, suggesting that their differentiation is halted at an early stage. We also find that the cloche mutation is not linked to flk-1. These data indicate that cloche affects the differentiation of all endothelial cells and that it acts at a very early stage, either by directly regulating flk-1 expression or by controlling the differentiation of cells that normally develop to express flk-1. cloche mutants also have a blood deficit and their hematopoietic tissues show no expression of the hematopoietic transcription factor genes GATA-1 or GATA-2 at early stages. Because the appearance of distinct levels of flk-1 expression is delayed in cloche mutants, we examined GATA-1 expression at late embryonic stages and found some blood cell differentiation that appears to be limited to the region lined by the flk-1-expressing cells. The spatial restriction of blood in the ventroposterior-most region of cloche mutant embryos may be indicative of a ventral source of signal(s) controlling hematopoietic differentiation. In addition, the restricted colocalization of blood and endothelium in cloche mutants suggests that important interactions occur between these two lineages during normal development.

Contrasting effects of growth hormone and insulin-like growth factor I on the biological activities of endotoxin in the rat

We previously demonstrated that GH potentiates the biological activities of endotoxin in the rat. In the present study, we wanted to determine if the potentiating effects of GH on the biological activities of endotoxin could be reproduced by insulin-like growth factor I (IGF-I). Endotoxin (5 mg/kg BW) was injected in rats primed with or without GH or IGF-I for 3 days. As expected, endotoxin administration markedly increased circulating tumor necrosis factor (TNF) and interferon-gamma (IFN gamma) and induced organ injury, hypoglycemia, and hyperlipidemia. In GH-primed rats, endotoxin induced a further increase of serum IFN gamma (but not TNF); and five out of six of those rats died within 15 h after giving endotoxin. However, little difference between endotoxin-treated rats with and without IGF-I priming could be seen. Furthermore, IGF-I infusion altered blood glucose, urea, and circulating ICF-I levels more than GH infusion. Therefore, IGF-I does not enhance the biological activities of endotoxin in the rat, suggesting that the enhancement of endotoxin effects by GH is via an IGF-I-independent pathway. Priming rats by GH (but not by IGF-I) induced a further increased response of serum IFN gamma but not TNF to subsequent endotoxin challenge, suggesting that IFN gamma rather than TNF is likely to be involved in this process.

Synthesis of a hexasaccharide acceptor corresponding to the reducing terminus of mycobacterial 3-O-methylmannose polysaccharide (MMP)

The title compound methyl O-(2,6-di-O-benzyl-3-O-methyl-alpha-D-mannopyranosyl)-[(1-->4) -O-(2,6-di-O-benzyl-3-O-methyl-alpha-D-mannopyranosyl)]4-(1-->4) -2,6-di-O-benzyl-3-O-methyl-alpha-D-mannopyranoside (2) was synthesized in a blockwise manner, employing trichloroacetimidate (11) and (20) as glycosyl donors. The strategy relies on the single-step preparation of the 3-O-methyl ethers (4) and (12) as starting materials. Since all intermediates contain one or more OCH3 groups, they are easily identified by NMR spectroscopy using the methyl proton signals. Compound 2 corresponds to the reducing terminal hexasaccharide of mycobacterial 3-O-methyl-mannose polysaccharide (MNP). MMP has the unusual property of stimulating the fatty acid synthetase multienzyme complex. Compound 2 can serve as a suitable glycosyl acceptor for the synthesis of extended fragments of MMP.

Major histocompatibility class II molecules in the CNS: increased microglial expression at the onset of narcolepsy in canine model

Human narcolepsy is a neurological disorder known to be closely associated with HLA-DR2 and DQB1*0602. Because most autoimmune diseases are HLA-associated, a similar mechanism has been proposed for narcolepsy. However, neither systemic nor CNS evidence of an autoimmune abnormality has ever been reported. In this study, major histocompatibility (MHC) class I and class II expression was studied in the CNS of human and canine narcoleptics using immunohistochemistry and Northern analysis. Results indicated that canine narcolepsy is associated with a significant increase of MHC class II expression by the microglia. Moreover, the highest values were found between 3 and 8 months of age, strikingly concomitant to the development of narcolepsy in the canine model. In humans, class II expression was not found significantly different between control and narcoleptic subjects. This result could be explained by the old age of the subjects (69.86 +/- 5.31 and 68.36 +/- 4.74 years in narcoleptics and controls, respectively), because class II expression is significantly correlated with age in both humans and dogs. For the first time, this study demonstrated that the expression of MHC class II molecules in the CNS is age-dependent and that a consistent increase of their expression by the microglia might be critically involved in the development of narcolepsy.

[Isolation of specific DNA probes from Cryptococcus neoformans]

OBJECTIVE

To construct plasmid library and screen specific DNA probes for Cryptococcus neoformans.

METHODS

Serotype A Cryptococcus neoformans was used as the study strain, plasmid pUC18 as vector, and Escherichia coli JM103 as host cell. The plasmid library of cryptococcus neoformans was constructed (pCN). Other pathogenes causing affection diseases which should be distinguished from cryptococcusis clinically, and other fungi similar to Cryptococcus neoformans with physiological and biochemical characteristics were used as a distinguishing system, specific colonies were screened by hibridization in double steps.

RESULTS

The inserts of the library were 280 to 1800 base pairs and 580 base pairs in average length. Repeated sequence was 32.43% and single copy sequence was 67.57% in genome of cryptococcus neoformans respectively. Three specific colonies were isolated from the library. Colony pCNII A6 was serotype A specific, pCNII B5 species specific and pCNIII G1-specific for var. neoformans.

CONCLUSION

A rapid diagnosis of Cryptococcus neoformans infection at early stage can be made by using species-specific probe, and serotype and variaty of neoformans and gattii be distinguished in epidemic study.

[Some aspects on surgical treatment of infratemporal fossa malignancies]

Thirteen patients with infratemporal fossa malignancies treated in the Sichuan Cancer Hospital from 1988 to 1993 are reported. All cases were treated surgically combined with pre-operative and post-operative radiotherapy with or without chemotherapy. The survival rate of the patients with survival period beyond 2 years was 53.8%. The survival was associated with the extent of dissection (P < 0.01). The operation value, surgical approaches, resection range, bone boundary of surgery, stylohamular line and repair are analysed and discussed.

Growth hormone potentiates the in vivo biological activities of endotoxin in the rat

To investigate if growth hormone (GH) alters the effects of endotoxin in rats, endotoxin (5 mg kg-1 body weight) was injected into normal rats and into rats primed with GH for 3 days. Endotoxin had injurious effects on renal and liver function and induced hypoglycaemia and hyperlipidaemia as expected. GH-primed rats became extremely sick after endotoxin challenge and had more marked abnormalities of renal and liver function and much more pronounced hypoglycaemia and hyperlipidaemia than non-primed rats. It is concluded that growth hormone potentiates the in vivo biological activities of endotoxin in the rat. The results may also suggest that caution should be exerted when considering GH treatment in catabolic situations with endotoxaemia and that special attention should be paid to the prevention of infection during GH therapy in such situations.

Endotoxin suppresses rat hepatic low-density lipoprotein receptor expression

Endotoxin induces hyperlipidaemia in experimental animals. In the current study, we investigated whether endotoxin alters hepatic low-density lipoprotein (LDL) receptor expression in rats. Endotoxin treatment suppressed hepatic LDL receptor expression in a dose- and time-dependent manner. Eighteen hours after intraperitoneal injection of increasing amounts of endotoxin, LDL receptor and its mRNA levels were determined by ligand blot and solution hybridization respectively. LDL receptor expression was inhibited by about 70% at a dose of 500 micrograms/100 g body weight. However, LDL receptor mRNA levels were markedly increased in all endotoxin-treated groups at this time point (by 83-136%; P < 0.001). Time-course experiments showed that LDL receptor expression was already reduced by 48% 4 h after endotoxin injection and was maximally reduced (by 63-65%) between 8 and 18 h. Changes in hepatic LDL receptor mRNA showed a different pattern. By 4 h after endotoxin injection, LDL receptor mRNA had decreased by 78% (P < 0.001). However, by 8 h after endotoxin injection, LDL receptor mRNA had returned to levels similar to controls, and 18 and 24 h after endotoxin injection, they were increased by about 60% (P < 0.05). Separation of plasma lipoproteins by FPLC demonstrated that endotoxin-induced changes in plasma triacylglycerols and cholesterol were due to accumulation of plasma apolipoprotein B-containing lipoproteins among very-low-density lipoprotein, intermediate-density lipoprotein and LDL. It is concluded that endotoxin suppresses hepatic LDL receptor expression in vivo in rats.

Activation of glycosylasparaginase. Formation of active N-terminal threonine by intramolecular autoproteolysis

The activation mechanism of glycosylasparaginase of Flavobacterium meningosepticum has been analyzed by site-directed mutagenesis and activation of purified precursors in vitro. Mutation of Thr-152 to Ser or Cys leads to gene products that are not activated in vivo but are activated in vitro because processing of the mutant precursors is inhibited by certain amino acids in the cell. Kinetic studies reveal that activation is an intramolecular autoproteolytic process. The involvement of His-150 and Thr/Ser/Cys-152 in activation suggests that autoproteolysis resembles proteolysis by serine/cysteine proteases. Multiple functions of the highly conserved active threonine residue are implicated.

[A comparison between astrocytoma cells and the developing astrocytes in human embryo brain by electron microscopy]

60 cases of astrocytoma of brain and 8 human embryo brains were studied with light and electron microscopy. The 5 types of tumor cells in astrocytoma include the undifferentiated, pre-astrocyte, astrocyte gemistocyte and tumor giant cells. Some similarities were found between the ultrastructure of astrocytoma and that of the developing astrocyte, the tumor cells somewhat resembling the cells of developing astrocytes. But certain differences were observed, the tumor cells were usually polymorphic with increased chromatin in nucleus, and asynchronism between nucleus and cytoplasm differentiation was sometimes found. The current nomenclature and classification of astrocytoma were evaluated and discussed, the author's opinion on classification was presented.

Phosphorylation and nuclear localization of the hepatitis B virus core protein: significance of serine in the three repeated SPRRR motifs

Hepatitis B virus core protein (antigen) is an important serologic marker of hepatitis B virus infection. This protein is found in the cytoplasm or the nuclei, or both, of infected hepatocytes. A nuclear localization signal has previously been identified in the core protein sequence. This signal overlaps three repeated SPRRR motifs. In this report, we demonstrate that substitution of all of the serine residues in these three SPRRR motifs with alanine can prevent almost entirely the phosphorylation of the core protein in Huh-7 hepatoma cells, enhance nuclear localization of the core protein in both Huh-7 and nonhepatic cells, and abolish cell cycle regulation of nuclear localization of the core protein. Since the three core protein mutants which retained only one serine residue of each of the three SPRRR motifs could be phosphorylated to similar degrees, these three serine residues likely could serve as the acceptor sites for phosphorylation with equal efficiency. These results, together with the observation that the three SPRRR motifs overlap the nuclear localization signal of the core protein, raise the possibility that nuclear localization of the core protein is negatively regulated by phosphorylation of the serine residues in the SPRRR motifs.

Upregulation of low density lipoprotein receptor activity by tumor necrosis factor, a process independent of tumor necrosis factor-induced lipid synthesis and secretion

It has been shown that tumor necrosis factor (TNF) rapidly upregulates expression of the low density lipoprotein (LDL) receptors on Hep G2 cells and acutely stimulates hepatic lipid synthesis and secretion in vivo. It may thus be possible that TNF-induced expression of LDL receptors is secondary to a decrease in cellular cholesterol content caused by TNF-stimulated lipid secretion. In order to know whether TNF upregulates LDL receptors by depletion of the cellular cholesterol content, the present experiments were designed to study the temporal relationship between TNF-stimulated expression of LDL receptor activity and TNF-induced changes in lipid synthesis and secretion in an in vitro setting by using Hep G2 cells (a highly differentiated human hepatoma cell line) as a hepatocyte model. Hep G2 cells were incubated with TNF (usually 2.5 nmol/L) for certain periods, and LDL receptor activity was evaluated by measuring [125I]LDL binding at 4 degrees C; lipid synthesis and secretion were assayed by measuring [3H]glycerol incorporation into triglycerides and phospholipids as well as [14C]acetate incorporation into cholesterol. We found that a 30-h exposure of the cells to TNF was needed for the effect of TNF to be seen on lipid synthesis and secretion as measured by incorporation of [3H]glycerol into triglycerides and phospholipids, whereas TNF rapidly (in several hours) upregulated LDL receptor activity. TNF stimulated triglyceride synthesis, but did not stimulate phospholipid synthesis. On the other hand, TNF stimulated phospholipid secretion, but did not stimulate triglyceride secretion. Exposure of the cells to TNF for 16 or 24 h neither decreased cholesterol synthesis nor stimulated cholesterol secretion as measured by [14C]acetate incorporation into cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Lactulose--a potential drug for the treatment of inflammatory bowel disease

Lactulose is a drug mainly used as a laxative and for the treatment of porto-systemic encephalopathy. Following oral administration, intact lactulose reaches the colon, where it is split by bacteria, leading to a reduction in faecal pH and creating intestinal conditions beneficial to Lactobacillus acidophilus and inhibitory to coliform bacteria, bacteroides, Salmonella and Shigella. It was shown that lactulose therapy clears faecal salmonella and shigella species and reduces the prevalence of urinary-tract infection and respiratory tract infections. Oral administration of lactulose abolishes and prevents systemic endotoxemia of gut origin. Therefore lactulose may be used for treatment of inflammatory bowel disease as bacteria and bacterial endotoxin have an important role in the pathogenesis of this disease.

[Clinical application of rhombotrapezious island musculocutaneous flap for skull base and/or craniomaxillary operation with malignant tumor]

Regional pedicled musculocutaneous flaps are the mainstay of the head and neck reconstruction. They provide a rapid, highly reliable and single-staged technique that is applicable in most cases. The rhombotrapezious island musculocutaneous flap is valuable in the base and craniomaxilloface reconstruction. In this study we updated our experience with the rhombotrapezious island musculocutaneous flap (RTIMF) in 6 cases from 1989 to 1993. Dissections were performed on 9 cadavers, 4 preserved and 5 fresh, yielding 18 pairs or dorsal scapular and transverse cervical artery for evaluation. In the five fresh cadavers, the arteries were selectively cannulated and injected with colored latex. 67% with dorsal scapular and transverse cervical artery commonly arose from the thyro-cervical trunk. 33% with the dorsal scapular artery directly arose from the second part of the subclavian artery. In the period of 1989-1993, 6 rhombotrapezious island musculocutaneous flaps with vascularized pedicle were used for immediate repair in the skull base or craniomaxillary cancer operations. There was no complication of the flaps. Donor site complications were relatively minor. The disturbance in shoulder function was well tolerated. We advocated the incorporation of both the greater and lesser rhomboid muscle to form the compound rhombotrapezious flaps to enhance the vascular supply to the overlying skin. The major advantage of the RTIMF are that it provides a long paddle of thin pliant, hairless skin and muscle that can be rotated as far as the craniomaxilloface and scalp in a single stage. It offers the longest arc of rotation and thus the greatest versatility for the skull base or craniomaxillary reconstruction.

[Comparison of protein assays for ejiao]

Ejiao exhibits identical spectral characteristics with those of reference gelatin in Murphy's UV spectrophotometry and color-yielding reactions performed according to Gornall's biuret and Lowry's Folin phenol procedures respectively. Results of protein assays of Ejiao measured by above-mentioned photometric methods were in good approximation to each other using gelatin as standard and comparable with that of Kjeldahl nitrogen determination.

Enhancement by lipoprotein-free plasma of the inhibitory effect of endotoxin on endocytotic catabolism of low density lipoproteins in Hep G2 cells

We previously showed that the presence of microgram levels of endotoxin inhibited low-density lipoprotein (LDL) uptake and degradation in Hep G2 cells. We also showed that both the polysaccharide and lipid A parts of endotoxins are needed for the inhibitory effects of endotoxins on cellular LDL uptake. The current study was carried out by inclusion of lipoprotein-free plasma (LFP) in tissue culture medium to observe the modulatory influence of non-lipoprotein factor(s) on endotoxin-induced inhibition of endocytotic catabolism of LDL in Hep G2 cells. We found that LFP dramatically promotes the inhibitory effect of endotoxins with a complete polysaccharide, but has no influence on the effect of the Re mutant endotoxin (from S. minnesota Re595), which lacks polysaccharide. By using gel-filtration chromatography, agarose electrophoresis and agarose isoelectric focusing, we further showed that in the presence of LFP, both the endotoxins with a complete polysaccharide and the Re mutant endotoxin complex with and anionize LDL, while in the absence of LFP, these endotoxins poorly interact with LDL. Thus, endotoxin inhibits cellular endocytotic catabolism of LDL by forming LDL-endotoxin complexes, and LFP enhances endotoxin-induced inhibition of endocytotic catabolism of LDL by promoting the interaction between endotoxin and LDL. In addition, our finding that the Re mutant endotoxin also interacts with LDL to form LDL-endotoxin complexes, but has no significant effect on LDL uptake and degradation, further supports the notion that both the polysaccharide and lipid A parts of endotoxins are needed for the inhibitory effects of endotoxins on cellular LDL uptake.

Interactions between cultured bovine arterial endothelial and smooth muscle cells: studies on uptake and degradation of low density lipoproteins by smooth muscle cells

This study was designed to investigate the effects of substances released from non-injured and injured bovine arterial endothelial cells on 125I-low density lipoprotein uptake and degradation by smooth muscle cells in culture. It was demonstrated that endothelial cell-released non-dialysable (molecular weight cut off 12-14000) substances significantly stimulated 125I-low density lipoprotein uptake and degradation by smooth muscle cells. Endothelial cell-released dialysable substances and endothelin-1 did not cause this stimulation. The increase in 125I-low density lipoprotein uptake and degradation by smooth muscle cells could be dissociated from cell proliferation. However, in endothelial cell-smooth muscle cell co-culture 125I-low density lipoprotein uptake and degradation by smooth muscle cells were not stimulated. Injury to endothelial cells by lipid-soluble smoke particles or ultraviolet light, which reduced total cellular protein by 15-25%, enhanced the endothelial cell release of the substances stimulating 125I-low density lipoprotein uptake. The results are discussed in relation to atherogenesis.

[A study on the transcriptional expression of oncogenes in human primary brain tumors]

The c-myc, L-myc, N-myc, Ha-ras, c-fos, and v-erbB oncogenes were used as probes to detect the total RNA of 5 cases of normal human brain tissues and 29 cases of brain tumor tissues by RNA dot hybridization analysis. The results showed that the increasing expressions of cerbB and c-fos were the highest, being 88.2% and 82.4%, respectively, the next was c-myc with an increased expression of 46.1%; the increasing expressions of L-myc (29.3%) and N-myc (31.6%) were observed in a few samples only. There was no significant difference of Ha-ras gene expression between normal brain and brain tumor. In addition, we observed the increasing expression of more than one oncogene in one sample. These results suggest that c-erbB and c-fos oncogenes may play an important role in the pathogenesis of human primary brain tumors, and that multiple genetic changes are implicated in genesis of human brain tumors.

Polymyxin B complexes with and cationizes low density lipoproteins. The cause of polymyxin B-induced enhancement of endocytotic catabolism of low density lipoproteins

We previously reported that polymyxin B (PMB) enhances cellular catabolism of low density lipoproteins (LDLs) through a non-LDL receptor-mediated endocytotic pathway. These data were obtained mainly by using Hep G2 cells, a well differentiated human hepatoma cell line. In the current study, we explore the mechanisms of PMB-mediated endocytotic catabolism of LDL. We found that PMB enhanced LDL catabolism also in homozygous familial hypercholesterolemia fibroblasts, thereby establishing that PMB-mediated cellular catabolism of LDL does not involve LDL receptors. By using [14C]sucrose, and ligands for the asialoglycoprotein (ASGP) receptors, possibilities were excluded that PMB enhances cellular endocytosis of LDL, by inducing a general increase of cellular pinocytic activity or by causing endocytosis of LDL via the ASGP receptors in Hep G2 cells. We further show, by using polymyxin B coupled Sepharose 4B (PMB-Sepharose 4B) beads, that PMB binds to LDL to form a complex. This binding was tight, and changes in pH and salt concentrations had no significant effect on the binding, but unlabelled LDL competed with 125I-LDL to bind to PMB-Sepharose 4B. Urea and endotoxins decreased this binding, suggesting that PMB binds to LDL at least partially through hydrophobic interactions. Agarose gel electrophoresis of PMB-LDL indicates that PMB cationizes LDL. In conclusion, PMB binds to LDL to form a PMB-LDL complex presumably through interactions between lipid groups. This endows LDL with positive charges, which enhances LDL binding to negatively charged cell membranes, and such bound LDL is rapidly internalized through absorptive endocytosis.

Retinoic acid is a negative regulator of the Epstein-Barr virus protein (BZLF1) that mediates disruption of latent infection

Disruption of latent Epstein-Barr virus (EBV) infection is induced by the key immediate-early protein BZLF1 (or Z, a member of the basic leucine-zipper family), which transactivates the viral early promoters. Viral reactivation is marked by renewed synthesis of early gene products such as EBV early antigen-diffuse (EA-D). Retinoic acid has been previously shown to inhibit reactivation of EBV infection. Retinoic acid responsive receptors are known to act as positively regulating transcription factors but can also negatively regulate AP-1 responsive genes. Here we demonstrate that the retinoic acid receptor alpha (RAR alpha) and retinoid X receptor alpha (RXR alpha) inhibit the ability of the Z protein to transactivate the viral early promoter BMRF1, which directs transcription of EA-D. Z can also reciprocally inhibit RAR alpha- and RXR alpha-induced activation of an autoregulated cellular promoter for the RAR beta gene (BRE) through a non-DNA binding mechanism. RXR alpha inhibits Z from binding to the AP-1 motif in the BMRF1 promoter and, reciprocally, Z inhibits RAR alpha from binding to its retinoic acid response element in the BRE promoter. Furthermore, a glutathione-S-transferase-RXR alpha fusion protein can interact directly with the Z protein. These results suggest that a direct protein-protein interaction between Z (the viral protein) and RAR alpha and RXR alpha (cellular proteins) can modulate the reactivation of latent EBV infection.