Reduction of myocardial ischemia-reperfusion injury by isovolumic hemodilution

In order to study the effects of isovolumic hemodilution and its combination with Danshen solution on acute ischemic reperfused canine myocardium, 24 adult hybrid dogs were used and divided into four groups. Group I was the control group, groups II-IV were treated with Dextron 40, Danshen solution and a combination of the two, respectively. The results showed that either Dextron 40 or Danshen solution alone had a significant increase of +/- dp/dt-max when compared with group I (p < 0.05). Although no significant difference existed between group II and III, the former showed more rapid action. The combination of the two therapies improved +/- dp/dt-max and LVSP, and significantly reduced the necrotic sizes and the MDA contents in the ischemic myocardia compared with not only group I, but also group II or group III (all p < 0.05). The results suggest that isovolumic hemodilution or Danshen may protect the ischemic reperfused myocardium and the former may come into action more rapidly, and that the combination of the two may show a better synergism than each one of the two by itself.

[Determination of six trace elements in steels by ICP-AES with the changed internal standard]

This paper studies the direct determination of P, Si, Mn, Cu, Cr and Ni in steels with the changed internal standard. The standard curves are standardized with FULL STANDARDIZATION, and the results of the sample are calibrated with TYPE STANDARD in time. The signal intensity influenced by RF power, observation height and sample gas folw is discussed. Results obtained for the determination of every element in steels are satisfactory. The RSD is less than 0.5% and the recovery is about 96-103%. The detection limit is about 0. 002-0.07%.

Comments on "A self-organizing network for hyperellipsoidal clustering (HEC)" [and reply]

In the above paper by Mao-Jain (ibid., vol.7 (1996)), the Mahalanobis distance is used instead of Euclidean distance as the distance measure in order to acquire the hyperellipsoidal clustering. We prove that the clustering cost function is a constant under this condition, so hyperellipsoidal clustering cannot be realized. We also explains why the clustering algorithm developed in the above paper can get some good hyperellipsoidal clustering results. In reply, Mao-Jain state that the Wang-Xia failed to point out that their HEC clustering algorithm used a regularized Mahalanobis distance instead of the standard Mahalanobis distance. It is the regularized Mahalanobis distance which plays an important role in realizing hyperellipsoidal clusters. In conclusion, the comments made by Wang-Xia together with this response provide some new insights into the behavior of their HEC clustering algorithm. It further confirms that the HEC algorithm is a useful tool for understanding the structure of multidimensional data.

[Evaluation for therapeutic efficacy of decompression of optic nerve canal in 121 cases]

OBJECTIVE

To evaluate the therapeutic efficacy of decompression of optic nerve canal in the eye with indirect nerve injury in the optic nerve canal.

METHODS

121 patients with indirect injury of optic nerve in the canal were selected and decompression of optic nerve canal was performed on them. Then the outcomes were reviewed and analyzed.

RESULTS

Visual acuities of 76 patients (62.81%) were improved.

CONCLUSION

It is obvious that decompression of optic nerve canal is associated with significant improvement in cases with good preoperative vision. In cases without light perception, treatment of steroids and dehydrant should be firstly applied, afterwards according to the patient's individual situation, selectively the case is to perform the operation. Thus the therapeutic effectiveness can be greatly elevated. Decompression of optic nerve canal is safe and reliable.

Nucleotide homologies in genes encoding members of the S100 protein family

Members of the S100 protein family exhibit a unique pattern of cell/tissue-specific expression and approx. 50% similarity at the amino-acid level. The cDNAs encoding many of these proteins from a variety of species are now available making a comparison of these family members at the nucleotide level possible. With few exceptions, family members exhibited less nucleotide identity than amino-acid similarity. Furthermore, the pattern of divergence calculated on the basis of nucleotide identity did not always agree with that calculated on the basis of amino-acid similarity. The majority of sequence diversity occurred in the nontranslated regions suggesting that these regions may be involved in directing the expression of particular members of the family to specific cell types. When comparisons of individual family members were made across species, the following order of species diversity was observed: rat/mouse < human/bovine < porcine < rabbit/avian < Xenopus laevis. The structure of the gene loci encoding these proteins was remarkably conserved both within family members of a given species as well as in individual family members from different species. Although there appears to be great diversity in the 5' flanking regions of these genes, members of the family share at least one common potential regulatory element-the S100 protein element. Thus, membership in the S100 family could be ascertained on the basis of gene organization and the presence of an SPE. Although functional data are limited, the available data indicate that the regulation of the expression of S100 family members is complex and involves both positive and negative regulatory elements. Additional nucleic acid sequences and complimentary functional studies will be required to dissect the mechanisms which target the expression of the members of this family to specific cell types during development.

Increased expression of PDGF and c-myc genes in lungs and pulmonary arteries of pulmonary hypertensive rats induced by hypoxia

The role of growth factors and proto-oncogene in pulmonary vascular structural remodelling is not well known. The present study examined gene expression of platelet-derived growth factor (PDGF)-A and -B chain and proto-oncogene, c-myc, in lung tissue and pulmonary artery of rats exposed to hypoxia and compared to those levels of gene expression in normal rats. Normal lungs and pulmonary artery expressed PDGF-A chain transcript of 1.7 kb and PDGF-B chain transcript of 3.5 Kb. The c-myc transcript of 2.2 kb was expressed as well. After hypoxic exposure for 7 and 14 days mRNA levels of PDGF-B chain and c-myc were elevated significantly compared with those of control rats. PDGF-A chain mRNA increased after hypoxia for 7 days, and then declined. These results suggest that activation of autocrine and/or paracrine is important in proliferation mechanism of pulmonary artery smooth muscle cells in hypoxic pulmonary hypertensive rats.

Effects of dietary cholesterol on hepatic production of lipids and lipoproteins in isolated hamster liver

The effect of 2-week 2% cholesterol vs. chow feeding on regulation of hepatic lipoprotein, lipids and apoprotein (Apo), and biliary lipids production was evaluated by the isolated perfused hamster liver model. Cholesterol feeding did not change very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) particle size but significantly increased the hepatic production of VLDL-cholesterol fourfold, VLDL-triglyceride two and one-half-fold but not phospholipid in VLDL. It also increased LDL-cholesterol fourfold but not triglyceride or phospholipid in LDL, whereas lipids in HDL remained unchanged. Gradient sodium dodecyl sulfate-polyacrylamide gel electrophesis (SDS-PAGE) and Western blot analysis (density of apoprotein/density of albumin/g liver) indicated that cholesterol feeding enhanced Apo B tenfold, Apo A-I fivefold but not Apo E in VLDL. Apo E and Apo B did not change in LDL. Apo E but not Apo A-I increased (threefold) in HDL by cholesterol feeding. Cholesterol feeding decreased bile salt secretion 28% but increased cholesterol secretion 118% in bile, whereas phospholipid and bile volume remained unchanged. Increased Apo A-I in VLDL suggested that Apo A-I is involved in enhanced hepatic export of cholesterol and triglyceride. Different patterns of lipid and Apos in VLDL and LDL after cholesterol feeding also suggested separate VLDL and LDL export mechanisms. Elevated Apo E but not lipids in HDL after cholesterol feeding suggests that hepatic HDL may function as a carrier of newly synthesized hepatic Apo E into the circulation for transfer to other lipoproteins (chylomicron [CM], CMr) to facilitate hepatic cholesterol uptake and clearance.

Delayed protection against ischaemia-induced ventricular arrhythmias and infarct size limitation by the prior administration of Escherichia coli endotoxin

1. Bacterial endotoxin (lipopolysaccharide derived from Escherichia coli) was injected intraperitoneally in conscious rats in doses ranging from 0.5 to 2.5 mg kg-1. At various times afterwards the animals were anaesthetized and subjected to a 30 min period of left coronary artery occlusion. 2. Under these conditions the severity of ventricular arrhythmias was markedly suppressed, in comparison with saline-injected controls, but this was particularly marked with the higher doses (1.5 and 2.5 mg kg-1); the number of ventricular premature beats was reduced from 1687 +/- 227 over the 0.5 h coronary artery occlusion period to 190 +/- 46 in those rats administered 2.5 mg kg-1 endotoxin 8 h previously (P < 0.05). The duration of ventricular tachycardia was also significantly reduced (138 +/- 26 s to 8.9 +/- 4.2 s; P < 0.01) and there was a reduction in the incidence of ventricular fibrillation (from 56% to 10%). 3. The time course of this protection was studied following the administration of a single dose of 2.5 mg kg-1 of endotoxin by anaesthetizing rats 4, 8 or 24 h later. Protection was apparent at each time but was particularly marked at 8 h. 4. No rat given the highest dose of endotoxin (32 in all) died as a result of ventricular fibrillation, or from any other cause, during an occlusion, in contrast to a 26% mortality in the controls (P < 0.01). 5. Infarct size, measured following a 30 min period of coronary artery occlusion followed by a 3 h reperfusion period, was reduced both 8 and 24 h after the administration of 2.5 mg kg-1 endotoxin (reductions of 24.3 and 23.1% respectively; P < 0.05). Endotoxin had no significant effect on the area at risk. 6. The beneficial effects of endotoxin on infarct size and on ventricular arrhythmias were markedly attenuated by the prior administration of dexamethasone, 3 mg kg-1 given 1 h prior to endotoxin administration. Dexamethasone itself reduced infarct size (P < 0.05) but had no direct effect on arrhythmia severity following coronary artery occlusion. 7. The mechanisms of this "cross-tolerance' induced by bacterial endotoxin against ischaemia-reperfusion injury remain to be elucidated but the most likely mechanisms appear to be the induction of protective enzymes or proteins (e.g. nitric oxide synthase, cyclo-oxygenase (COX) 2) probably mediated by cytokine release.

Protein phosphatase type 1 interacts with proteins required for meiosis and other cellular processes in Saccharomyces cerevisiae

Protein phosphatase type I (PP1) is involved in diverse cellular processes, and its activity toward specific substrates is thought to be controlled by different regulatory or targeting subunits. To identify regulatory subunits and substrates of the Saccharomyces cerevisiae PP1, encoded by GLC7, we used the two-hybrid system to detect interacting proteins. Among the many proteins identified were Gac1, a known glycogen regulatory subunit, and a protein with homology to Gac1. We also characterized a new gene designated GIP1, for Glc7-interacting protein. We show that a Gip1 fusion protein coimmunoprecipitates with PP1 from cell extracts. Molecular and genetic analyses indicate that GIP1 is expressed specifically during meiosis, affects transcription of late meiotic genes, and is essential for sporulation. Thus, the Gip1 protein is a candidate for a meiosis-specific substrate or regulator of PP1. Finally, we recovered two genes, RED1 and SCD5, with roles in meiosis and the vesicular secretory pathway, respectively. These results provide strong evidence implicating PP1 function in meiosis. In addition, this study indicates that the two-hybrid system offers a promising approach to understanding the multiple roles and interactions of PP1 in cellular regulation.

Delayed cardioprotection is associated with the sub-cellular relocalisation of ventricular protein kinase C epsilon, but not p42/44MAPK

Both noradrenaline administration to rats and rapid cardiac pacing in dogs induces delayed protection of the heart against ischaemia-induced ventricular arrhythmias. In an attempt to establish molecular mechanisms underlying the delayed cardioprotection, we have examined the potential role of two kinases, PKC epsilon and p42/44MAPK. These protein kinases are expressed in the ventricles of the heart and are characterised by their ability to regulate ion-flux and gene transcription. In the rat p42MAPK is predominantly localised in the high-speed supernatant fraction of the ventricle homogenate, whereas p44MAPK is enriched in the nuclear low speed pellet. A small proportion of the p42MAPK is activated even in hearts from control animals. However, neither kinase is relocalised or activated by noradrenaline administration and this provides preliminary evidence the p42/44MAPK may not play a significant role in delayed protection in this species. In contrast, noradrenaline does induce the translocation of PKC epsilon to cell membranes, a response that is sustained for up to 4 h. However, PKC epsilon is down-regulated from the cytoplasm after 24 h post noradrenaline treatment. PKC epsilon is also translocated to the membrane in dogs that have been classically pre-conditioned and cardiac paced. In the latter case, translocation of PKC epsilon from the cytoplasm to the cell membrane is evident 24 h after pacing. These results indicate that the release of endogenous mediators may either inhibit down-regulation or elicit an increase in PKC epsilon mRNA expression. Therefore, in dog heart the subcellular relocalisation of PKC epsilon persists into the 'second window' and may play a central role in the molecular mechanism governing delayed cardioprotection. It is important in the future to identify either the gene products that are induced or the target protein(s) that are phosphorylated by PKC epsilon.

Active expression of G gamma globin gene on chromosome 11 with Yunnanese A gamma delta beta)0-thalassemia deletion in MEL cells

A permanent lymphocyte cell line of a heterozygote with Yunnanese (A gamma delta beta)0-thalassemia deletion, associated with an increased production of G gamma globin in adult, was founded using Epstein-Barr virus transformation. The hybrids of the lymphocyte cell and mouse erythroleukemia cell (MEL) were achieved and the hybrids containing human chromosome 11 were selected with the monoclonal antibody 53/6. The subclones containing only either the normal or the abnormal human chromosome 11 were separated and the expression of the human globin genes was studied. Expression of the beta-globin gene, but not the G gamma and A gamma, was observed in the hybrids containing only the normal human chromosome 11, while active expression of the G gamma globin gene was observed in the hybrids containing only the abnormal human chromosome 11. These results have confirmed that the DNA deletion in the beta-globin gene cluster is the cause of persistent active expression of the G gamma globin gene in the Yunnanese mutant.

Expression of the rat S100A1 gene in neurons, glia, and skeletal muscle

Using a rat S100A1 cDNA probe, S100A1 expression has been documented in rat C6 glioma cells, a cell line previously thought to express only the S100B protein. To identify the molecular mechanisms which target S100A1 gene expression to specific cell types, the rat S100A1 gene was cloned, and functional analysis of the 5' flanking region of the gene was performed. The rat S100A1 gene was located in an 8.5 kb BamHI genomic fragment which contained 3 exons plus 1.6 kb of 5'-upstream and 0.37 kb of 3'-downstream flanking sequence. A single transcription initiation start site and a single polyadenylation signal were identified in this gene. A number of potential regulatory consensus sequences were identified in the rat S100A1 gene including general transcription factor binding sequences (TATA box, GC box and CCAAT box), cAMP regulated sequences (CRE), skeletal muscle specific sequences (E-box and M-CAT), an S100 protein element, and a (GCT) trinucleotide repeat. Analysis of an S100A1 promoter-CAT construct by ribonuclease protection assay demonstrated that this gene is functional in three S100A1 expressing cell lines, C6 cells, PC12 cells and L6 cells. CAT constructs containing progressive deletions of the S100A1 promoter region revealed a positive regulatory element in skeletal muscle (L6) cells between -1600/-1081. The fact that these same sequences were negative in glial (C6) cells and neutral in neuronal (PC12) cells suggests that this region plays a major role in targeting S100A1 expression to specific cell types. The -1081/+10 region contained both positive and negative elements, some of which were cell-type specific. Thus, S100A1 expression is under complex transcriptional control which involves positive and negative elements as well as cell type specific elements.

Endogenous 7-oxocholesterol is an enzymatic product: characterization of 7 alpha-hydroxycholesterol dehydrogenase activity of hamster liver microsomes

Previously, we described a new metabolite derived from endogenous cholesterol in the presence of hamster liver microsomal protein and NADPH (Song et al., 1991, Biochem. Pharmacol. 41, 1439-1447). Through gas chromatography/mass spectral analysis of the metabolite and its methoxime-3-dimethyl-t-butylsilyl ether derivative, this metabolite has been definitively identified as 7-oxocholesterol. Isotope incorporation experiments using molecular 18O2 demonstrated that no oxygen atoms from molecular oxygen were incorporated into the product, 7-oxocholesterol, when 7 alpha-hydroxycholesterol was used as substrate. In contrast, one atom of 18O was incorporated into cholesterol from 18O2 during its metabolism to form 7 alpha-hydroxycholesterol. Formation of 7-oxocholesterol was dependent upon the presence of NADP+, 7 alpha-hydroxycholesterol, and hamster liver microsomes. This enzyme appears to be a membrane-bound protein and its activity was most abundant in liver microsomal fractions and to a lesser extent in mitochondrial fractions; little or no activity was observed in nuclei or cytosol. The enzyme activity was present in highest content in the livers of hamsters and was also observed in human and bovine liver microsomes, but not those of mouse, rabbit, or rat. The reaction was inhibited by 2'-AMP, but not by anti-NADPH:cytochrome-P450 oxidoreductase globulin, carbon monoxide, metyrapone, nor miconazole. In contrast to the previously characterized 3 beta-hydroxy-delta 5-C27-steroid oxidoreductase activity, NAD+ did not serve as an effective cofactor for 7-oxocholesterol formation. The ability of NADPH to partially serve as a cofactor in this reaction was shown to be due to a high NADPH-oxidase activity of hamster liver microsomes, thereby providing sufficient NADP+ to serve as the oxidizing pyridine nucleotide for the reaction. These results document the existence of a non-P450, NADP(+)-dependent 7 alpha-hydroxycholesterol dehydrogenase in liver microsomes which catalyzes this reaction. The product, 7-oxocholesterol, is produced enzymatically in the livers of hamsters and other mammals and may regulate bile acid metabolism or other processes due to its action as an oxysterol.

Role of endogenous cholecystokinin in the regeneration of pancreatic tissue after acute hemorrhagic pancreatitis in rats

The aim of this study was to investigate the effect of endogenous cholecystokinin (CCK) on pancreatic regeneration after acute hemorrhagic pancreatitis. Acute hemorrhagic pancreatitis was induced in rats by two intraperitoneal cerulein injection (20 micrograms/kg BW) with 5h water-immersion stress once a day for successive 3 days. After the cessation of repetition of acute pancreatitis the rats were treated with successive feeding with 0.1% camostat-containing diet or SC injection of CR-1505 (CCK receptor antagonist, 50 mg/kg BW x 2/day) for 7 days. Zymogen enzymes and protein contents per DNA in pancreatic tissue were significantly higher in rats treated with camostat compared with control rats, and plasma CCK level was elevated. To the contrary, pancreatic regeneration was retarded in the rats treated with CR 1505. It is concluded that endogenous CCK has a trophic effect during regeneration after acute hemorrhagic pancreatitis.

Cloning of a second Arabidopsis peptide transport gene

Previously, we reported the isolation of a peptide transport gene designated AtPTR2 from Arabidopsis thaliana by functional complementation of a yeast peptide transport mutant. We now report the isolation of a second peptide transport gene (AtPTR2-B) from Arabidopsis using the same approach. Similar to the effects of transferring AtPTR2-A (previously called AtPTR2), transfer of AtPTR2-B to yeast peptide transport mutants restored the ability to grow on di- and tripeptides but not peptides four residues or longer. However, unlike yeast mutants complemented with either the yeast PTR2 gene or the AtPTR2-A gene, transformants expressing AtPTR2-B were only partially sensitive to toxic peptides. Northern analysis showed that AtPTR2-B was constitutively expressed in all plant organs. Studies of the kinetics indicated that AtPTR2-A and AtPTR2-B have Km values of 47 and 14 microM, respectively, with Vmax values of 0.061 and 0.013 nmol mg-1 cell dry weight s-1, respectively, when dileucine was used as a substrate. AtPTR2-B is encoded on a 2.0-kb cDNA corresponding to a 585-amino acid protein (64.4 kD). Hydropathy analysis indicates that the protein is highly hydrophobic and suggests that there are 12 putative transmembrane segments. AtPTR2-B, like AtPTR2-A, shares significant similarity to a number of other proteins involved in transport of peptides into cells.

[The effects of retinoic acid on the ultrastructure of cultured fibroblasts]

The paper reports the effects of retinoic acid on the ultrastructure of cultured fibroblasts. Electron microscopic observation (SEM and TEM) showed that fibrous substances on the cell surface and outside the cell had decreased. The results indicated that retinoic acid inhibits collagen synthesis of fibroblasts. The possible mechanism of the effect of retinoic acid in the treatment of scar is discussed.

SSN genes that affect transcriptional repression in Saccharomyces cerevisiae encode SIN4, ROX3, and SRB proteins associated with RNA polymerase II

The RNA polymerase II of Saccharomyces cerevisiae exists in holoenzyme forms containing a complex, known as the mediator, associated with the carboxyl-terminal domain. The mediator includes several SRB proteins and is required for transcriptional activation. Previous work showed that a cyclin-dependent kinase-cyclin pair encoded by SSN3 and SSN8, two members of the SSN suppressor family, are identical to two SRB proteins in the mediator. Here we have identified the remaining SSN genes by cloning and genetic analysis. SSN2 and SSN5 are identical to SRB9 and SRB8, respectively, which encode additional components of the mediator. Genetic evidence implicates the SSN genes in transcriptional repression. Thus, these identities provide genetic insight into mediator and carboxyl-terminal domain function, strongly suggesting a role in mediating transcriptional repression as well as activation. We also show that SSN4 and SSN7 are the same as SIN4 and ROX3, respectively, raising the possibility that these genes also encode mediator proteins.

Isla Vista virus: a genetically novel hantavirus of the California vole Microtus californicus

Prospect Hill virus (PH) was isolated from a meadow vole (Microtus pennsylvanicus) in 1982, and much of its genome has been sequenced. Hantaviruses of other New World microtine rodents have not been genetically characterized. We show that another Microtus species (the California vole M. californicus) from the United States is host to a genetically distinct PH-like hantavirus, Isla Vista virus (ILV). The nucleocapsid protein of ILV differs from that of PH by 11.1% and a portion of the G2 glycoprotein differs from that of PH by 19.6%. ILV antibodies were identified in five of 33 specimens of M. californicus collected in 1975 and 1994-1995. Enzymatic amplification studies showed that 1975 and 1994-1995 ILV genomes were highly similar. Secondary infection of Peromyscus californicus was identified in Santa Barbara County, California. A long-standing enzootic of a genetically distinct hantavirus lineage is present in California voles.

Molecular linkage of hantavirus pulmonary syndrome to the white-footed mouse, Peromyscus leucopus: genetic characterization of the M genome of New York virus

The complete M segment sequences of hantaviruses amplified from tissues of a patient with hantavirus pulmonary syndrome in the northeastern United States and from white-footed mice, Peromyscus leucopus, from New York were 99% identical and differed from those of Four Corners virus by 23%. The serum of this patient failed to recognize a conserved, immunodominant epitope of the Four Corners virus G1 glycoprotein. Collectively, these findings indicate that P. leucopus harbors a genetically and antigenically distinct hantavirus that causes hantavirus pulmonary syndrome.

Entry of B cell antigen receptor and antigen into class II peptide-loading compartment is independent of receptor cross-linking

The processing and presentation of Ag by B lymphocytes are initiated by Ag binding to the B cell Ag receptor (BCR). Using subcellular fractionation, we recently identified a compartment in B cells in which functional, processed Ag-class II complexes are formed following BCR-mediated Ag internalization, referred to as the peptide-loading compartment. These studies, however, did not address the transport of Ag or BCR from the cell surface to the peptide-loading compartment. In this work, we describe the intracellular trafficking of Ag and surface Ig (sIg) in B cells and evaluate the effect of cross-linking sIg on this intracellular movement. We show that sIg constitutively transports Ag from the plasma membrane, through endosomes, to the MHC class II peptide-loading compartment. The cross-linking of the BCR increases the rate of internalization of sIg and bound Ag, but does not alter the trafficking pathway. Thus, the delivery of Ag to the class II peptide-loading compartment by the sIg is independent of BCR cross-linking, but can be influenced by BCR cross-linking.

Entry of B cell antigen receptor and antigen into class II peptide-loading compartment is independent of receptor cross-linking

The processing and presentation of Ag by B lymphocytes are initiated by Ag binding to the B cell Ag receptor (BCR). Using subcellular fractionation, we recently identified a compartment in B cells in which functional, processed Ag-class II complexes are formed following BCR-mediated Ag internalization, referred to as the peptide-loading compartment. These studies, however, did not address the transport of Ag or BCR from the cell surface to the peptide-loading compartment. In this work, we describe the intracellular trafficking of Ag and surface Ig (sIg) in B cells and evaluate the effect of cross-linking sIg on this intracellular movement. We show that sIg constitutively transports Ag from the plasma membrane, through endosomes, to the MHC class II peptide-loading compartment. The cross-linking of the BCR increases the rate of internalization of sIg and bound Ag, but does not alter the trafficking pathway. Thus, the delivery of Ag to the class II peptide-loading compartment by the sIg is independent of BCR cross-linking, but can be influenced by BCR cross-linking.

Retroviral vector-transduced cells expressing the core polyprotein induce feline immunodeficiency virus-specific cytotoxic T-lymphocytes from infected cats

The core polyprotein of feline immunodeficiency virus (FIV) was expressed in primary feline T-lymphocytes using a retroviral vector. These cells were used as antigen-presenting stimulator cells (APSC) for the in vitro induction of cytotoxic T-lymphocytes (CTL) from feline peripheral blood mononuclear cells (PBMC). CTL from 4 cats chronically infected with the Petaluma strain of FIV specifically lysed autologous FIV-infected targets in an MHC-restricted manner. The CD8 phenotype of more than 70% of the induced effector cells (97% for cells from one cat) was consistent with MHC class I-restricted cytotoxicity. In addition, it was possible to detect low levels of core polyprotein-specific lysis from effector cells of two of the FIV-infected cats. When observed, the level of lysis, measured as a percentage of specific 111In release, was lower for the transgenic gag-expressing targets than for FIV-infected targets. The difference in killing may reflect the low level of core CTL were not detected in either PBMC stimulated with cells transduced by a retroviral vector without the FIV gag sequence or PBMC from an uninfected cat stimulated with autologous transgenic APSC. The detection of FIV-specific CTL from infected cats following stimulation with transgenic APSC suggests a role for retroviral vectors in determining CTL specific for individual lentiviral proteins in protective immunity.

Intracellular transport of invariant chain-MHC class II complexes to the peptide-loading compartment

Th cells recognize peptide fragments of foreign Ags bound to MHC class II molecules. Upon synthesis in the endoplasmic reticulum, the alpha- and beta-chains of the class II molecules rapidly associate with invariant chains (li). The dissociation of li from class II molecules precedes binding of processed Ag and the formation of SDS-stable alpha beta dimers. We previously showed that functional, processed Ag-class II complexes are assembled in a dense lysosome-like compartment that contains stable class II molecules, but no li, referred to in this work as the peptide-loading compartment. We also identified a separate compartment that contains predominantly SDS-unstable li-class II complexes. Because we were unable to identify known organelle markers associated with this compartment, we refer to it as the X compartment. In this work, we provide results that indicate that the X compartment is composed of transport vesicles that move li-class II complexes to the peptide-loading compartment, where all events in the assembly of processed Ag-class II complexes occur.

Intracellular transport of invariant chain-MHC class II complexes to the peptide-loading compartment

Th cells recognize peptide fragments of foreign Ags bound to MHC class II molecules. Upon synthesis in the endoplasmic reticulum, the alpha- and beta-chains of the class II molecules rapidly associate with invariant chains (li). The dissociation of li from class II molecules precedes binding of processed Ag and the formation of SDS-stable alpha beta dimers. We previously showed that functional, processed Ag-class II complexes are assembled in a dense lysosome-like compartment that contains stable class II molecules, but no li, referred to in this work as the peptide-loading compartment. We also identified a separate compartment that contains predominantly SDS-unstable li-class II complexes. Because we were unable to identify known organelle markers associated with this compartment, we refer to it as the X compartment. In this work, we provide results that indicate that the X compartment is composed of transport vesicles that move li-class II complexes to the peptide-loading compartment, where all events in the assembly of processed Ag-class II complexes occur.

Efficient transfection of DNA by mixing cells in suspension with calcium phosphate

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Nucleotide sequence analysis of the M genomic segment of El Moro Canyon hantavirus: antigenic distinction from four corners hantavirus

El Moro Canyon hantavirus (ELMC, previously known as HMV-1) is associated with the western harvest mouse Reithrodontomys megalotis. The interpretation that ELMC is a novel hantavirus was based upon comparisons of the nucleotide sequence of the S genomic segment with those of other hantaviruses. We now show that the ELMC M genome, like the S genome, is genetically similar to but distinct from that of Four Corners hantavirus (FC). The ELMC M genome is 3801 nt in length and encodes a glycoprotein precursor of 1139 amino acids. The G1 and G2 genes are 71 and 73.1% identical to those of FC and the corresponding glycoproteins are 73.5 and 82.3% identical. A portion of the G1 glycoprotein of ELMC that is homologous to an important linear epitope of FC differs from the FC epitope by 10 of 31 residues. That domain and flanking sequences were expressed in Escherichia coli. G1 antibodies from 3 of 19 FC-infected patients showed cross-reactivity with ELMC by Western blot assay. The portion of the ELMC G1 antigen recognized by those antibodies is the region of homology to the FC epitope. These data support our previous interpretation that ELMC is distinct from FC and other hantaviruses.

Dimeric and tetrameric IgA are transcytosed equally by the polymeric Ig receptor

Polymeric IgA (pIgA) is transcytosed across epithelial cells and into external secretions by the polymeric Ig receptor (pIgR). Binding of dimeric IgA (dIgA) to the pIgR stimulates transcytosis of the pIgR. The pIgA in secretions is found as dimers (dIgA) and higher polymers, such as tetramers (tIgA), but little is known of the functional significance of the different sizes. Here we compared the ability of dIgA and tIgA to perform three functions that are essential to their transport into mucosal secretions. 1) Equilibrium binding studies showed that there were twice as many binding sites for tIgA as dIgA at the basolateral cell surface, but that the affinity of these sites for tIgA was one-half of that for dIgA. 2) Both dIgA and tIgA were rapidly transcytosed by the pIgR, although transcytosis of tIgA was slower. 3) Both dIgA and tIgA could stimulate transcytosis of the pIgR, although tIgA was less effective. The possible implications of these findings for the relative biologic roles of dIgA and tIgA are discussed.

Dimeric and tetrameric IgA are transcytosed equally by the polymeric Ig receptor

Polymeric IgA (pIgA) is transcytosed across epithelial cells and into external secretions by the polymeric Ig receptor (pIgR). Binding of dimeric IgA (dIgA) to the pIgR stimulates transcytosis of the pIgR. The pIgA in secretions is found as dimers (dIgA) and higher polymers, such as tetramers (tIgA), but little is known of the functional significance of the different sizes. Here we compared the ability of dIgA and tIgA to perform three functions that are essential to their transport into mucosal secretions. 1) Equilibrium binding studies showed that there were twice as many binding sites for tIgA as dIgA at the basolateral cell surface, but that the affinity of these sites for tIgA was one-half of that for dIgA. 2) Both dIgA and tIgA were rapidly transcytosed by the pIgR, although transcytosis of tIgA was slower. 3) Both dIgA and tIgA could stimulate transcytosis of the pIgR, although tIgA was less effective. The possible implications of these findings for the relative biologic roles of dIgA and tIgA are discussed.

Feline immunodeficiency virus (FIV)-specific cytotoxic T lymphocytes from chronically infected cats are induced in vitro by retroviral vector-transduced feline T cells expressing the FIV capsid protein

We have previously reported the presence of feline immunodeficiency virus (FIV)-specific, major histocompatibility complex (MHC)-restricted cytolytic T lymphocytes (CTL) in experimentally FIV-infected cats. However, the fine specificity of the CTL and the role of individual FIV proteins in inducing FIV-specific CTL responses remain unknown. In this study, we examined the in vitro induction and activity of FIV p24 capsid-specific CTL obtained from cats that had been experimentally infected with FIV Petaluma for 30 to 56 months. An amphotropic murine retroviral vector was used to generate transgenic primary feline T lymphoblasts that expressed the FIV capsid protein. When the autologous capsid-transduced T cells were used in vitro to stimulate CTL responses from peripheral blood mononuclear cells of chronically infected cats, MHC-restricted lysis of virus-infected target cells was observed. The majority of the CTL expressed CD8, and depletion of this population, but not CD4+ cells, effectively diminished the CTL activity. When the autologous capsid-transduced T cells were used as target cells, lysis by capsid-induced effectors was not observed. Analysis of capsid-transduced T cell clones revealed a variable and low level of capsid expression among the clones. This study demonstrates the potential for using retroviral vectors as a means of inducing CTL effector cells that will specifically kill lentivirus-infected cells during lentiviral infection.

[Structural changes of extra pulmonary artery and pulmonary arterioles of rats during chronic hypoxia and their significance]

The structural changes of extra pulmonary artery (PA) and pulmonary arterioles and their effects on the pulmonary arterial pressure (PAP) under chronically hypobaric hypoxia (5000 m) were studied. The results showed that (1) The endothelial edema of extra PA and pulmonary arterioles gradually reduced and the endothelial proliferation took place along with the prolongation of hypoxic exposure followed by the recovery of endothelium-dependent relaxation evoked by Ach from depression. This result suggested that the release of E-DRFs from endothelium increased with the structural changes of endothelium in the course of hypoxic exposure, which may be a reason why PAP did not increase any more after 21 to 40 of days exposure. However, the strengthened contraction of PA, the proliferation of cells on the vascular wall, and the muscularity of pulmonary arterioles being related to the hypoxic endothelium may produce a negative effect on decrease of PAP, resulting in persistently higher PAP. (2) The structural changes of pulmonary arteriole endothelium were more severe than those of extra PA endothelium, indicating that pulmonary arterioles might be more sensitive to the stimulation of hypoxia.

Prevalence and geographic genetic variation of hantaviruses of New World harvest mice (Reithrodontomys): identification of a divergent genotype from a Costa Rican Reithrodontomys mexicanus

We recently described a novel hantavirus (HMV-1) of the western harvest mouse Reithrodontomys megalotis. Screening of 181 additional specimens of Reithrodontomys from the United States and Mexico, including samples of R. mexicanus, R. sumichrasti, and R. gracilis of Costa Rica, for antibodies to hantavirus nucleocapsid protein revealed a widespread enzootic of hantavirus infection. Genetic analyses of 7 S genomes of Reithrodontomys-associated hantaviruses demonstrated that the enzootic of HMV-1 extends from central Mexico into the southwestern United States. A presumed deer mouse hantavirus was found in an R. megalotis animal in Mexico. A highly divergent HMV-1-like virus, tentatively called HMV-2, was identified in a Costa Rican R. mexicanus. These data suggest a longstanding radiation of hantaviruses among New World harvest mice. We identify possible opportunities for genetic exchange among hantaviruses of related rodent hosts.

[The effect of retinoic acid on DNA synthesis of fibroblast in vitro culture]

The effect of retinoic acid on DNA synthesis of fibroblast was studied in vitro culture. The results demonstrated that retinoic acid significantly (P < 0.01) inhibited the DNA synthesis of fibroblast in vitro culture and a dose-dependent relationship between DNA synthesis and retinoic acid concentration was observed. The possible mechanism of retinoic acid used for the treatment of scar was discussed.

The intracellular assembly of antigenic-peptide-class II complexes

The immune system employs remarkable strategies to ensure that foreign antigens, from the most complex pathogens to the simplest proteins, are displayed on the surfaces of cells which are targets of T lymphocyte recognition. At the heart of these strategies is the molecular transformation of a soluble protein antigen to a complex of a small peptide containing the antigenic determinant bound to a cell surface Major Histocompatibility Complex class I or class II protein. This process is termed antigen presentation. Progress in a variety of laboratories over the last several years has yielded a wealth of information about the molecular mechanisms underlying antigen presentation, providing potential new approaches to vaccine design. Here we describe recent studies in our laboratory aimed at elucidating the intracellular site in B lymphocytes in which antigenic peptide-class II complexes are assembled for recognition by helper T cells and the regulation of this assembly process. Our results suggest that processed antigen-class II complexes are assembled in a unique compartment in the endocytic route which contains all the necessary cellular and molecular machinery for assembly and that B cells regulate the assembly process in response to external and internal signals.

Immunoglobulin and non-immunoglobulin components of human milk inhibit Clostridium difficile toxin A-receptor binding

Clostridium difficile is isolated from the intestinal tracts of > 50% of healthy infants. The mechanism by which intestinal colonisation of infants by toxigenic C. difficile is generally asymptomatic is unknown but may reflect the presence in human milk of neutralising activity against C. difficile toxin A. On this basis, the ability of human milk to inhibit the binding of toxin A to a purified hamster brush border membrane receptor was determined. Ten milk samples from healthy volunteers in various stages of lactation inhibited the binding of toxin A to the receptor by an average of 90%. Heating and dialysis did not significantly alter the inhibitory activity of any of the milk samples. Human milk protected adult hamsters against a lethal challenge with toxin A but had no effect on the cytotoxic activity of the toxin. SDS-PAGE and ligand blot analyses showed that there were at least four distinct factors in human milk that specifically bound toxin A. Thiophilic adsorption chromatography was used to separate immunoglobulin from non-immunoglobulin components of human milk. IgA was the only immunoglobulin detected in human milk and > 90% of this immunoglobulin was recovered after purification by thiophilic adsorption. Both the unbound non-immunoglobulin and bound immunoglobulin fractions of human milk inhibited the binding of toxin A to the purified receptor. These results suggest that human milk may be important in protecting infants against C. difficile-associated intestinal disease.

Tumor suppressive role of an androgen-regulated epithelial cell adhesion molecule (C-CAM) in prostate carcinoma cell revealed by sense and antisense approaches

We recently demonstrated that C-CAM, an epithelial-cell adhesion molecule of the immunoglobulin supergene family, could be regulated by androgen and might act as a growth repressor during differentiation of the prostatic epithelium. To define the role of C-CAM in prostatic tumorigenesis, a tumorigenic human prostatic cancer cell line, PC-3, was transfected with an expression plasmid containing C-CAM1 (a C-CAM isoform). Transfected clones showed significantly lower growth rates, reduced anchorage-independent growth, and less tumorigenicity in vivo than control cells. Furthermore, transfection of an antisense vector into a nontumorigenic prostatic epithelial cell line, NbE, resulted in tumor formation in nude mice. Sublines derived from these NbE-induced tumors had lower levels of C-CAM than did control cells. These data suggest that C-CAM1 can function as a tumor suppressor in prostate tumorigenesis.

The S100 protein family: history, function, and expression

The S100 family of calcium binding proteins contains approximately 16 members each of which exhibits a unique pattern of tissue/cell type specific expression. Although the distribution of these proteins is not restricted to the nervous system, the implication of several members of this family in nervous system development, function, and disease has sparked new interest in these proteins. We now know that the original two members of this family, S100A1 and S100B, can regulate a diverse group of cellular functions including cell-cell communication, cell growth, cell structure, energy metabolism, contraction and intracellular signal transduction. Although some members of the family may function extracellularly, most appear to function as intracellular calcium-modulated proteins and couple extracellular stimuli to cellular responses via interaction with other cellular proteins called target proteins. Interaction of these proteins with target proteins appear to involve cysteine residues (one in S100A1 and two in S100B), as well as a stretch of 13 amino acids, in the middle of the molecule called the linker region, which connects the two EF-hand calcium binding domains. In addition to the amino acid sequence and secondary structures of these proteins, the structures of the genes encoding these proteins are highly conserved. Studies on the expression of these proteins have demonstrated that a complex mixture of transcriptional and postranscriptional mechanisms regulate S100 expression. Further analysis of the function and expression of these proteins in both nervous and nonnervous tissues will provide important information regarding the role of altered S100 expression in nervous system development, function and disease.

Attenuation by dexamethasone of endotoxin protection against ischaemia-induced ventricular arrhythmias

Ventricular arrhythmias from a 30 min occlusion of the left coronary artery were assessed in Langendorff perfused isolated hearts removed from rats administered either saline, or endotoxin derived from Escherichia coli (2.5 mg kg-1 i.p.) given either 2, 4, 8, 24 or 48 h previously. Arrhythmia severity was markedly reduced in those hearts removed from rats administered endotoxin with a maximum protection at 8h; there was a marked reduction in the incidence of ventricular fibrillation (from 54% to 4%) and in the number of ventricular premature beats during the occlusion period (e.g. from 1165 +/- 144 to 37 +/- 19; P < 0.01). Dexamethasone (3 mg kg-1, given 1 h prior to endotoxin or saline) markedly attenuated the protection afforded by endotoxin.

Transcytosis of the polymeric immunoglobulin receptor is regulated in multiple intracellular compartments

Transcytosis of the polymeric immunoglobulin receptor (pIgR) can be experimentally divided into three steps: 1) internalization from the basolateral plasma membrane and delivery to basolateral early endosomes, 2) microtubule-dependent movement from basolateral early endosomes to apical recycling endosomes, and 3) delivery from apical recycling endosomes to the apical surface and cleavage of the pIgR to secretory component, which is released into the apical medium. Transcytosis of the pIgR is stimulated by two signals, phosphorylation of Ser-664 in the cytoplasmic domain of the pIgR and binding of the ligand, dimeric IgA, to the pIgR. These signals do not detectably alter step 1 of transcytosis. Here, we show that phosphorylation of Ser-664 stimulates both steps 2 and 3, whereas binding of dimeric IgA stimulates only step 3 of transcytosis.

Requirement for RGR1 and SIN4 in RME1-dependent repression in Saccharomyces cerevisiae

RME1 is a zinc-finger protein homolog that functions as a repressor of the meiotic activator IME1. RME1 is unusual among yeast repressors in two respects: it acts over a considerable distance (2 kbp) and it can activate transcription from a binding site separated from its natural flanking region. To identify genes required for RME1 to exert repression, we have selected mutants with improved RME1-dependent activation. One rare mutant was defective in RME1-dependent repression of an artificial reporter gene as well as the native IME1 gene. The mutation permits sporulation of a/a diploids, which express RME1 from its natural promoter, and of a/alpha diploids constructed to express RME1 from the GAL1 promoter. The mutation also causes temperature-sensitive growth and a methionine or cysteine requirement. Analysis of a complementing genomic clone indicates that the mutation lies in a known essential gene, RGR1. Prior studies have indicated a functional relationship between RGR1 and SIN4 (also called TSF3); we have found that a sin4 null mutation also causes a defect in RME1-dependent repression and a methionine or cysteine requirement. The rgr1 and sin4 mutations do not cause a reduction of RME1 polypeptide levels. The defect in RME1-dependent repression may result from effects of sin4 and, presumably, rgr1 on chromatin structure.

An Arabidopsis peptide transporter is a member of a new class of membrane transport proteins

An Arabidopsis peptide transport gene was cloned from an Arabidopsis cDNA library by functionally complementing a yeast peptide transport mutant. The Arabidopsis plant peptide transporter (AtPTR2) allowed growth of yeast cells on dipeptides and tripeptides but not peptides four residues and higher. The plant peptide transporter also conferred sensitivity to a number of ethionine-containing, toxic peptides of chain length three or less and restored the ability to take up radiolabeled dileucine at levels similar to that of the wild type. Dileucine uptake was reduced by the addition of a variety of growth-promoting peptides. The sequence of a cDNA insert of 2.8 kb indicated an open reading frame encoding a 610-amino acid polypeptide (67.5 kD). Hydropathy analysis predicted a highly hydrophobic protein with a number of potential transmembrane segments. At the amino acid level, the Arabidopsis plant peptide transporter shows 24.6, 28.5, and 45.2% identity to the Arabidopsis nitrate-inducible nitrate transporter (CHL1), the rabbit small intestine oligopeptide transporter (PepT1), and the yeast peptide transporter (Ptr2p), respectively, but little identity to other proteins known to be involved in peptide transport. Root growth of Arabidopsis seedlings exposed to ethionine-containing toxic peptides was inhibited, and growth was restored by the addition of certain peptides shown to compete with dileucine uptake in yeast expressing the Arabidopsis transport gene. Consistent with the observed inhibition of root growth by toxic peptides, the peptide transporter is expressed in the roots of Arabidopsis seedlings. This study represents the characterization of a plant peptide transporter that is a member of a new class of related membrane transport proteins.

[The phenotypic change of smooth muscle cells in the media of pulmonary intra-acinar arteries during hypoxia]

The phenotypic change of smooth muscle cells (SMCs) in the media of pulmonary intraacinar arteries (IAA) was observed in rats during hypoxia. From 3 to 40 exposure days, pulmonary arterial pressure (PAP) and right ventricular hypertrophy increased parallely. From 1 to 5 exposure days, SMCs still displayed the "contractile" phenotype, but the amount of intercellular collagen slightly increased. After 7 exposure days, some medial SMCs changed into the "fully" or "partially" "synthetic" phenotype with an excess of intercellular collagen. From 14 to 40 exposure days, other than some SMCs of partially "synthetic" phenotype, a great number of SMCs acquired the "contractile" phenotype characteristics, but the synthetic and secretive organelles and intercellular collagen were still more than those in the groups from 1 to 5 exposure days. Our results suggested that along with the prolongation of hypoxic exposure, the kinetic changes of SMC phenotype might not parallel with PAP change.

Rapid internalization of the polymeric immunoglobulin receptor requires phosphorylated serine 726

S726 of the cytoplasmic domain of the polymeric immunoglobulin receptor (pIgR) resides within a consensus sequence for phosphorylation by protein kinases A, G, and C, and casein kinase II. Mutation of S726 to Ala and expression of this mutant pIgR in Madin-Darby canine kidney cells results in a receptor in which steady-state phosphorylation is reduced to 49% of wild-type levels. This mutant receptor is also significantly impaired in its internalization from the basolateral membrane. During the first minute, internalization of radioiodinated ligands (either dIgA or monovalent anti-pIgR Fabs) by this mutant pIgR is only 35% of that by wild-type pIgR. Internalization of unoccupied mutant receptors is similarly inhibited. Delivery of newly made mutant receptor from the trans-Golgi network to the basolateral surface is completely normal. The only other trafficking step inhibited by this mutation is the transcytosis of radioiodinated dIgA. Within 2 h, the mutant pIgR will transcytose 58% of a preinternalized cohort of dIgA, while the wild-type transcytoses 76%. This inhibition of transcytosis may be an indirect consequence of impaired internalization. The correlation between the loss of phosphorylation and inhibition of internalization suggests that phosphorylation of S726 may represent a novel mechanism for regulation of internalization of the pIgR.