Synthesis, conformational analysis, and the glycosidic coupling reaction of substituted 2,7-dioxabicyclo[4.1.0]heptanes: 1,2-anhydro-3,4-di-O-benzyl-beta-L- and beta-D-rhamnopyranoses

1,2-Anhydro-3,4-di-O-benzyl-alpha-L-rhamnopyranose was synthesized from L-rhamnose, while the D-enantiomer was synthesized from methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-mannopyranoside. For both of the syntheses, the key intermediates were 2-O-acetyl-3,4-di-O-benzyl-alpha-D- and -alpha-L-rhamnopyranosyl chlorides that were quantitatively prepared from the corresponding diacetates by chlorination. Ring closure of the chlorides was carried out readily with potassium tert-butoxide in oxolane, and crystalline 1,2-anhydro-3,4-di-O-benzyl-beta-D- and beta-L-rhamnopyranose were obtained in high yields. Conformational calculations, which were carried out using vicinal proton-proton coupling constants by the modified Karplus equation, suggested that the conformations of the pyranose rings of the title compounds were basically a half chair (4H5) with some flattening at C-4. Force-field calculations (MMP2) confirmed the experimental conformation with good agreement. The coupling reaction of the 1,2-anhydro-L-rhamnose ether with 1,2;3,4-di-O-isopropylidene-alpha-D-galactopyranose was effected in oxolane by catalysis by a Lewis acid, and only the alpha-linked disaccharide was obtained.

Desaturation and chain elongation of n - 3 and n - 6 polyunsaturated fatty acids in the human CaCo-2 cell line

Human CaCo-2 cells were incubated with [14C]linoleic (18:2(n - 6)), [14C]linolenic (18:3(n - 3)) and [3H]eicosapentaenoic acid (20:5(n - 3)), and the interconversion of the radioactive fatty acids to higher homologues and their acylation into triacylglycerols (TG) and phospholipids were examined. An active conversion of [14C]18:3 to [14C]20:5 and [14C]docosapentaenoic acid (22:5(n - 3)) and of [3H]20:5 to [3H]22:5, but not to [3H]docosahexaenoic acid (22:6(n - 3)) was observed. In relation to the amounts that had been incorporated into cellular phospholipids and TG, the interconversion of [14C]18:3 clearly exceeded that of [14C]18:2. Addition of 10-100 microM 18:2 or 10-50 microM arachidonic acid (20:4(n - 6)) increased the percent interconversion of [14C]18:2 to [14C]20:4. E.g., addition of 50 microM 20:4 increased the formation of [14C]20:4 from 4.4 +/- 0.1% to 5.9 +/- 0.8%, decreased the incorporation into phospholipids from 64.8 +/- 6.3% to 31.4 +/- 1.2% and increased the incorporation into TG from 8.8 +/- 0.4% to 28.8 +/- 1.1%. In contrast, addition of 10-100 microM 18:3 or 20:5 significantly decreased the interconversion of both [14C]18:2 and [14C]18:3. E.g., addition of 50 microM 20:5 decreased the formation of [14C]20:4 from [14C]18:2 from 4.4 +/- 0.1% to 0.9 +/- 0.1%, whereas the effects on the acylation reactions were very similar to those of 20:4. 20:5 also decreased the formation of interconversion products from [14C]18:3. 18:2 and 20:4 caused a smaller decrease in the formation of [14C]20:5 and actually increased percent conversion to [14C]22:5. The percent conversion of [3H]20:5 to [3H]22:5 was also increased by the addition of 50-100 microM unlabeled 20:5. [14C]18:2 and [14C]18:3 were predominantly incorporated into phosphatidylcholine (PC) whereas more of the radioactive 20:4, 20:5 and 22:5 was incorporated into phosphatidylethanolamine (PE). An active fatty acid interconversion catalyzed by delta 6 and delta 5 desaturases thus occurs in the human CaCo-2 cell line, whereas conversion of 20:5(n - 3) to 22:6(n - 3) could not be demonstrated. The desaturation-elongation pathway has a preference for 18:3(n - 3) and is subjected to an efficient feedback regulation by 20:5(n - 3). Formation of 22:5 increases with available 20:5 mass and by the presence of other polyunsaturated fatty acids competing with 20:5 for acylation into phospholipids.

Type II collagen during cartilage and corneal development: immunohistochemical analysis with an anti-telopeptide antibody

We have examined the pattern of immunoreactivity of a monoclonal antibody, II-5B2, with specificity for an epitope which resides within the NH2-terminal extension peptide (telopeptide) of the avian type II collagen molecule. This epitope is available in regions of matrix where de novo synthesis of the molecule is ongoing, but not where synthesis has ceased and maturation and crosslink formation have occurred. Within the cartilaginous growth plate, the epitope disappears from the matrix soon after the chondrocytes become hypertrophic; within the cornea, the epitope disappears subjacent to the epithelium. The II-5B2 epitope is not made available by a variety of procedures shown to remove potentially masking substances and to disrupt fibrillar organization. It is rendered available, however, when covalent crosslink formation between collagen molecules is blocked through administration of beta-aminopropionitrile or penicillamine. In contrast, the epitope of another monoclonal antibody against type II collagen, II-II6B3, which resides in the triple-helical domain of the molecule, in cartilage is present throughout the growth plate including the hypertrophic zone, and in cornea extends for a considerable distance into the stroma. Thus, it is available for antibody binding regardless of fibril maturation and crosslinking. These data suggest that the II-5B2 epitope becomes unavailable when the telopeptide becomes crosslinked. By using these two monoclonal antibodies in serial sections, one can establish the crosslinking pattern of type II collagen in the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Chicken tibial dyschondroplasia: a limb mutant with two growth plates and possible defects of collagen crosslinking

In the cartilaginous epiphyseal growth plate, extracellular matrix molecules such as collagens are believed to play important roles during both normal and abnormal development. One defect of the epiphyseal plate occurs in chickens with a condition termed tibial dyschondroplasia (TD). This abnormality occurs in certain strains of juvenile chickens and other rapidly developing animals. It is characterized by the presence of a mass of avascular, uncalcified cartilage which is retained in the proximal metaphysis of the tibiotarsus. To elucidate the developmental events which may be involved in this lesion, we have performed both immunohistochemistry and in situ hybridizations for collagen types II and X, known components of the extracellular matrix of the growth plate. By immunohistochemical analyses, the TD lesion contains both of these collagen types; therefore, the presence of these molecules per se is not sufficient for calcification of vascularization to occur. Since type X collagen is expressed exclusively in hypertrophic cartilage, the chondrocytes in the lesion must have undergone hypertrophy before their developmental arrest. The matrix of the lesion also reacted with a monoclonal antibody which is directed against an epitope in the NH2-terminal telopeptide of the alpha 1(II) chain. Our previous data suggest that this epitope is rendered unavailable in type II collagen which has undergone crosslink formation; its availability in the lesion suggests that crosslinking may be abnormal. Lastly, analyses by in situ hybridization failed to detect mRNA for either type II or type X collagen within the lesion, but chondrocytes distal to the lesion do contain mRNAs for these collagens in a spatial pattern suggesting the presence of a second growth plate.

Regulation of the cellular stress response by reactive electrophiles. The role of covalent binding and cellular thiols in transcriptional activation of the 70-kilodalton heat shock protein gene by nephrotoxic cysteine conjugates

The cytotoxicity of nephrotoxic cysteine conjugates (NCC) in the renal epithelial cell line, LLC-PK1, is due to the covalent binding of a reactive electrophilic metabolite produced from NCC metabolism by cysteine conjugate beta-lyase. Covalent binding of NCC-derived reactive metabolites leads to a cascade of events including depletion of cellular non-protein sulfhydryls, increased cytosolic free calcium, and lipid peroxidation, which is ultimately responsible for cell death. We have used this model to investigate the signalling mechanism(s) through which reactive electrophiles increase synthesis of the 70-kD heat shock protein (HSP70). NCC treatment resulted in increased HSP70 synthesis as well as time- and dose-dependent increases in hsp70 mRNA in LLC-PK1 cells. The induction of hsp70 mRNA was blocked by actinomycin D, and nuclear run-on experiments showed that the hsp70 gene was transcriptionally activated. Inhibition of protein synthesis did not block the increase in hsp70 mRNA or transcriptional activation of the hsp70 gene suggesting that induction occurs due to activation of existing transcription factors. Inhibiting the covalent binding with a beta-lyase inhibitor, aminooxyacetic acid, blocked the increase in hsp70 mRNA. Agents which do not alter binding but do prevent toxicity by blocking the rise in cytosolic free calcium and lipid peroxidation were not effective inhibitors of hsp70 mRNA accumulation. However, the thiol reducing agent, dithiothreitol, inhibited induction of hsp70 mRNA by NCC. The data suggest that covalent binding and alterations in cellular non-protein thiols serve as signals for activation of pre-existing transcription factors which increase hsp70 gene expression. It is proposed that reactive electrophiles may have a primary effect on protein conformation resulting in activation of the hsp70 gene.

Studies on epitopes on low-density lipoprotein modified by 4-hydroxynonenal. Biochemical characterization and determination

Oxidation of human low-density lipoprotein (LDL) was found to be accompanied by the generation of various reactive aldehydes. One of them, 4-hydroxynonenal (HNE), was shown to modify LDL to a form which represents a good model of oxidized LDL (ox-LDL). In order to investigate the epitopes newly formed on HNE-modified LDL, a polyvalent antiserum to HNE-LDL [anti-(HNE-LDL)] was raised in rabbits and the non-specific components were removed with native LDL coupled to CNBr-Sepharose 4B. Competitive fluorescence immunoassay analysis showed that anti-(HNE-LDL) recognized HNE-LDL, copper-oxidized LDL, HNE-albumin and to a lower extent HNE-modified high-density lipoprotein 3 (HNE-HDL3) and ox-HDL3 but not native LDL. A certain degree of cross-reactivity of the antibody with LDLs modified by either hexanal or 2,4-heptadienal was found. No reaction was obtained with LDL labelled with malondialdehyde. From the abilities of HNE-modified poly(L-amino acids) to compete with HNE-LDL for binding to anti-(HNE-LDL), it is postulated that lysine, tyrosine, arginine and histidine are involved in the formation of HNE-derived epitopes on apolipoprotein B (apo B). Using a double-sandwich fluorescence immunoassay [capture antibody: anti-(apo B); detection antibody: anti-(HNE-LDL)] we found that the HNE-derived epitopes were expressed at a far higher degree in ox-LDL and HNE-LDL than in native LDL.

[Lead concentrations in urine correlated with cytogenetic damages in workers exposed to lead]

The lead concentrations in urine and the frequency of chromosomal aberrations and sister chromatid exchanges in lymphocytes of 84 printers exposed to lead were investigated. The results demonstrated that the lead concentrations in urine of printers were higher than normal subjects. The frequency of chromosomal aberrations and sister chromatid exchanges increased significantly with the rise of lead concentrations in urine, showing a linear correlation. The regression equations were Y = 1.31 + 9.07 X and Y = 4.24 + 14.91 X respectively. Therefore, the genetic condition of workers who have high lead concentrations in urine should be attended to and appropriate protective measures should be under-taken.

The effect of light fluence rate in photodynamic therapy of normal rat brain

This paper reports the effect of incident light fluence rate on the depth to which necrotic lesions are produced by photodynamic therapy (PDT) in the brains of normal Fisher rats. The rats were injected intraperitoneally with Photofrin (12.5 mg kg-1) 48 h prior to PDT with a fixed incident fluence of 35 J cm-2. The treatment was performed at 10, 50, 100, and 200 mW cm-2 and also in a periodic manner (30 s "on" at 100 mW cm-2, 30 s "off"). The depth to which necrosis occurred was determined 24 h after treatment by microscopic examination of tissue sections. No differences were found in the depth to which necrosis was produced by any of the five irradiation schedules. This finding is discussed in the context of other published dose-rate experiments.

Isolation and characterization of a cDNA encoding a synaptonemal complex protein

A gene encoding a 65-kilodalton antigen of the rat synaptonemal complex, SC65, has been cloned by screening rat testis λgt11 and λZAPII cDNA expression libraries using polyclonal antibodies against rat synaptonemal complex proteins. The longest open reading frame, initiating at an ATG codon in the cDNA, encodes a protein of 431 amino acids, with a relative molecular mass of 50 000. Immunological analysis locates the SC65 gene product on the synaptonemal complex between the pairing faces of the parallel aligned cores of homologous chromosomes in spermatocytes. Of the rat tissues examined, the SC65 gene is transcribed in testis, brain, and heart at similar levels, and in the liver at a much lower level. The DNA sequence extending about 80 base pairs downstream of the translation termination codon has 93% similarity to the identifier sequence present in the rat genome in 1 × 105 – 1.5 × 105 copies and in cDNA clones of precursors of brain-specific mRNAs. The amino acid sequence encoded by the SC65 gene contains an acidic region in the C-terminal domain of the protein, potential glycosylation sites, and at least one possible phosphorylation site. The protein shows no overall similarity to proteins of known function, nor is there similarity to protein sequences present in GenBank or EMBL data bases.Key words: meiosis, synaptonemal complex, antibody, rat testis cDNA library, molecular cloning.

Induction of dystrophin localization in cultured Xenopus muscle cells by latex beads

The distribution of dystrophin in Xenopus myotomal muscle cells was examined in conventional and confocal immunofluorescence microscopy. By labeling dissociated single muscle fibers with a monoclonal or a polyclonal antibody against dystrophin, we found that dystrophin is ten times more concentrated at the myotendinous junction (MTJ) than at the extrajunctional sarcolemma. At the MTJ, dystrophin lines the membrane invaginations where myofibrils attach to the membrane. It is colocalized with talin, but is not related to the distribution of acetylcholine receptors (AChRs) which are clustered at the postsynaptic membrane in the vicinity of the MTJ in these fibers. We found that the localization of dystrophin can be induced in cultured Xenopus myotomal muscle cells by treating them with polystyrene latex beads. Dystrophin is discretely localized at the bead-muscle contacts. With electron microscopy, a sarcolemma specialization with all the salient features of the MTJ, including basal lamina-lined membrane invaginations along which myofibrils make attachment. Although these beads also induce clustering of AChRs, the patterns of dystrophin and AChR localization are distinct. The appearance of dystrophin at the bead-contacted sarcolemma is coincident with the development of the membrane invaginations. This, together with its concentration along membrane invaginations at the MTJ in vivo, suggests a role for dystrophin in the formation of this junctional specialization. Since the signal for MTJ development can be presented to cultured muscle cells in a temporally and spatially controlled manner by beads, this system offers a simple model for analyzing the mechanism of this sarcolemma specialization.

Magnetoencephalography of focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

The purpose of this study was to use magnetoencephalography to record magnetic field changes in the brain during middle cerebral artery occlusion.

METHODS

A direct-current electrocorticogram (two channels) and a direct-current magnetoencephalogram (seven channels) were simultaneously recorded from five rats subjected to middle cerebral artery occlusion for 1-2 hours.

RESULTS

Direct-current electrocorticographic and direct-current magnetoencephalographic signal deflections were observed after the onset of middle cerebral artery occlusion and occurred repeatedly throughout the ischemic period, with a mean +/- SD time interval of 12 +/- 5 minutes. A one-to-one correspondence of the electrocorticographic and magnetoencephalographic signal deflections was demonstrated.

CONCLUSIONS

Direct-current magnetoencephalography can provide a new noninvasive technique for studying depolarization and/or spreading depression in focal cerebral ischemia.

[Effects of calcium channel blocker verapamil on hippocampal kindled seizures induced by coriaria lactone in rabbits]

Eighteen fully kindled rabbits, whose epilepsy had been produced by intrahippocampal (i.h.) injections of 2 microliters of diluted solution containing 0.32 or 0.55 micrograms of coriaria lactone (CL), were separated into three groups. One of them was used as the control group. For seizure, all animals were given CL (0.6-1 micrograms/2 microliter i.h.). Ten minutes later, the verapamil (VR) group of six rabbits was treated with VR (1.5 or 2 mg/kg i.m. 2.5 or 5 micrograms/2 microliters i.h.); the normal saline (NS) group (six rabbits) received 0.8 ml/kg (i.m., in the same volume as that of the VR 2 mg/kg injection) or 2 microliters (i.h.) of NS; the control group of six received neither VR nor NS. The experiments were made once every eight days. Hippocampal EEGs of all animals were recorded by telemetric method and their behavior after injection was observed continuously in 4-7 hours. The results of the experiment indicated that the i.h. administration of 2.5 or 5 micrograms/2 microliters of VR is effective on hippocampal kindled seizures induced by CL in rabbits, but the curative effects of the i.m. administration of 1.5 or 2 mg/kg of VR were less notable than those of the i.h. administration.

Effects of light beam size on fluence distribution and depth of necrosis in superficially applied photodynamic therapy of normal rat brain

The light fluence distributions of 632.8 nm light incident on the exposed surface of normal rat brain in vivo have been measured using an interstitial, stereotactically-mounted optical fiber detector with isotropic response. The dependence of the relative fluence rate on depth and the spatial distribution of fluence were compared for incident beam diameters of 3 and 5 mm. The fluence rate at depth of 1-6 mm along the optical axis within the brain tissue was approximately 70% greater for a 5 mm diameter beam than for a 3 mm beam, at the same incident fluence rate, although the plots of the relative fluence rate vs depth were parallel over the depth range 1-6 mm. The depths of necrosis resulting from photodynamic treatment of brain tissue using the photosensitizer Photofrin and irradiation by 632 nm light with 3 and 5 mm incident beams were also measured. The observed difference in necrosis depths was consistent with the measured difference in fluence. The importance of beam size in photodynamic treatment with small diameter incident light fields is discussed.

Lipoprotein receptor mediated metabolism of [14C]arachidonic acid labeled chylomicron remnants by Hep G2 cells

During lipolysis of chylomicron triacylglycerol by lipoprotein lipase, arachidonic acid (AA) esters are hydrolyzed at a slower rate than the predominant 16-18 carbon fatty acid esters. The further metabolism of the AA that is hereby enriched in the chylomicron remnant acylglycerols has not been investigated. In the present study, we examined the low density lipoprotein (LDL) dependent and independent metabolism of [14C]AA present in chylomicron remnants in the human hepatoma cell line Hep G2. Mesenteric duct cannulated rats were fed [14C]AA and [3H]cholesterol in corn oil, and the chyle obtained was injected intravenously into hepatectomized rats to form chylomicron remnants labeled with [14C]AA in the triacylglycerol (TG) and with 3H in the cholesteryl ester portion. The remnants were then incubated with Hep G2 cells. The uptake of [14C]AA within 2-4 h was similar to that of [3H]cholesteryl ester. After uptake into the cells, [14C]AA was preferentially incorporated into phospholipids, a high proportion being found in phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol. [14C]AA and [3H]cholesteryl ester uptake were influenced to similar extents by factors unknown to regulate the LDL receptor and by an anti-LDL receptor antibody. Addition of compactin thus increased the uptake of [14C]AA by 50% in 4 h and mevalonolactone decreased the uptake by 86%. Using an anti-LDL receptor antibody, 25.0% of [3H]cholesterol/cholesteryl ester and 37.7% of [14C]AA binding to the cells at 4 degrees C were blocked. There was no lipolysis of [14C]TG or [14C]diacylglycerol by lipase secreted into the medium during incubations.(ABSTRACT TRUNCATED AT 250 WORDS)

Production and cytogenetic analysis of BC1, BC 2, and BC 3 progenies of an intergeneric hybrid between Triticum aestivum (L.) Thell. and tetraploid Agropyron cristatum (L.) Gaertn

Intergeneric hybrids between Triticum aestivum cv 'Chinese Spring' and Agropyron cristatum 4x (2n= 5x=35, ABDPP genomes) with a high level of homoeologous meiotic pairing between the wheat chromosomes were backcrossed 3 times to wheat. Pollination of the F1 hybrid with 'Chinese Spring' resulted in 22 BC1 seeds with an average seed set of 1.52%. Five BC1 plants with 39-41 chromosomes were raised using embryo rescue techniques. Chromosome pairing in the BC1 was characterized by a high frequency of multivalent associations, but in spite of this there was no evidence of homoeologous pairing between chromosomes of wheat and those of Agropyron. All of the plants were self sterile. The embryo rescue technique was again essential to produce 39 BC2 plants with chromosome numbers ranging from 37 to 67. The phenomenon of meiotic non-reduction was also observed in the BC3 progenies. In this generation male and female fertility greatly increased, and meiotic pairing was fairly regular. Some monosomic (2n=43) and double monosomic (2n=44) lines were produced. Analysis of these progenies should permit the extraction of the seven possible wheat-Agropyron disomic addition lines including those with the added chromosomes carrying the genes involved in meiotic non-reduction and in suppression of Ph activity.

High-resolution computed tomography of the mammalian lung

High-resolution computed tomography (HRCT) was performed in 21 isolated animal lungs, from 4 mammalian species (pigs, rabbits, dogs, sheep). Gross and subgross central and peripheral lung morphology was determined by HRCT. Three distinct types of lungs can be identified, principally based on the extent of interlobular septal development; the relationship of major vessels to airways; and the thickness of the visceral pleura. Type-I lung is found in pigs, sheep, and cattle; type-II lung is found in rabbits, dogs, cats, and monkeys; and type-III lung is found in human beings and horses. These mammalian lungs were compared with human lungs. The potential use of HRCT to investigate specific human lung diseases in the aforementioned species also was considered.

Induction of acetylcholine receptor clustering by native polystyrene beads. Implication of an endogenous muscle-derived signalling system

Aneural muscle cells in culture often form acetylcholine receptor (AChR) clusters, termed hot spots, which are similar to those found at the postsynaptic membrane both in structure and in molecular composition. Although hot spots form on both dorsal and ventral surfaces of the cell, the ventral ones are better characterized because of their association with sites of cell-substratum contact. To understand the stimuli and mechanisms involved in ventral hot spot formation, native, uncoated polystyrene beads were applied to cultured Xenopus myotomal muscle cells to create local membrane-substratum contacts. These beads were able to induce a postsynaptic-type development as evidenced by the clustering of AChRs and the development of a set of ultrastructural specializations, including membrane infoldings and a basement membrane. Whereas these native beads were effective in inducing clustering, beads coated with bovine serum albumin or treated with serum-containing medium were ineffective. Native beads were also capable of inducing clusters in serum-free medium, indicating that their effect was mediated by endogenous molecules that were locally presented by the beads, rather than by bead adsorption of components in the medium. Heparan sulfate proteoglycan (HSPG) is a major component of the muscle extracellular matrix and our previous study has shown that basic fibroblast growth factor (bFGF), a member of the heparin-binding growth factor (HBGF) family, and its receptor are present in Xenopus myotomal muscle during the period of synaptogenesis. Therefore, we tested the involvement of HBGF in bead induction. The results of this study show the following: (1) preincubation of cultures in heparin, which solubilizes matrix-bound HBGFs, suppressed the bead-induced AChR clustering. (2) Suramin, which interferes with the interaction between several growth factors and their receptors, also inhibited bead-induced clustering. (3) Tyrphostin, which blocks tyrosine kinase activity associated with a number of growth factor receptors, was also inhibitory to the bead effect. (4) The percentage of bead-induced AChR clusters was significantly enhanced by pretreating the cultures with bFGF prior to bead application. This exogenously applied bFGF could be largely removed by treatment of cultures with heparin, suggesting its association with HSPG at the cell surface. (5) An anti-bFGF neutralizing antiserum significantly reduced the efficacy of the bead stimulation. These data suggest that uncoated beads, which adhere to the cell surface and can mimic the cell-substratum interaction, effect a local presentation of HBGFs, such as bFGF, residing with the HSPG to their membrane receptors, thereby locally activating receptor-associated tyrosine kinases.(ABSTRACT TRUNCATED AT 400 WORDS)

Antioxidative effect of polyphenol extract prepared from various Chinese teas

METHODS. Twelve different types of Chinese teas, including green, semifermented, and black tea, were studied for their antioxidant activities and active components. Compositions of (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate, and gallic acid were identified by fast atom bombardment-mass spectrometry and high-performance liquid chromatography-mass spectrometry and quantified by high-performance liquid chromatography. Antioxidant activities in lard were measured by the Rancimat method. RESULTS. The results showed that both yields of polyphenol extract and antioxidant activities varied with different tea processing methods. It was found that (-)-epigallocatechin gallate, (-)-epigallocatechin, and (-)-epicatechin gallate inhibited soybean lipoxygenase at the IC50 values ranging from 10 to 20 microM.

[Ultrastructural observation of SC1001-sodium on brain neurons kindled seizures by coriaria lactone in rabbits]

The ultrastructural changes of hippocampus and cerebral cortex neurons were derived from the rabbits kindled by coriaria lactone and from the kindled rabbits after treatment with SC1001 Na. The results of experiment showed that the hippocampus and cerebral cortex neurons in the kindled group had some degenerative changes, such as the swelling mitochondria, dilated rough endoplasmic reticulum and Golgi complexes when the injuries of neurons were not serious, but the seriously injured neurons were subjected to rupture of the cell membrane and solution of most organella, with only a small amount of degenerative organella. In the group treated with SC1001 Na, the ultrastructure of brain neurons demonstrated a tendency of recreation to normal which showed that SC1001 Na had cured many of the degenerative brain cells. This suggested that active treatment is very important for the epileptic patients.

Rabbit lung surfactant protein A gene: identification of a lung-specific DNase I hypersensitive site

Expression of the gene encoding pulmonary surfactant protein A, SP-A, is lung specific and developmentally and hormonally regulated. Previously, we observed that SP-A gene transcription is initiated in fetal rabbit lung after day 21 of gestation and reaches maximal levels by day 28. In the present study, a cDNA specific for rabbit SP-A was used to isolate the SP-A gene from a rabbit genomic library. A 7.6-kb fragment containing the entire structural gene and approximately 380 bp of 5'-flanking DNA was isolated and characterized. The transcription initiation site, mapped by primer extension analysis, was localized 23 bp downstream of a putative TATA element. The structural gene is composed of five exons and four introns. The first exon encodes the 5'-untranslated region of the mRNA; the translation initiation site is in exon II, and exon V contains the two polyadenylation sites that give rise to the 2.0- and 3.0-kb species of SP-A mRNA. A potential adenosine 3',5'-cyclic monophosphate (cAMP)-regulatory element (CRE) was identified at -261 bp, and sequences with homology to glucocorticoid-regulatory element (GRE) half-sites were found at -150 and -190 bp upstream of the transcription initiation site and within the first intron. A DNase I hypersensitive site was identified in genomic DNA isolated from 21- and 28-day fetal and adult rabbit lung tissues. This site was mapped within the 5'-flanking region of the SP-A gene, at approximately -80 to -180 bp upstream of the transcription initiation site. The absence of this hypersensitive site in genomic DNA of liver, kidney, and heart tissues suggests that altered chromatin structure may serve a role in lung-specific SP-A gene expression. The presence of this tissue-specific DNase I hypersensitive site in lung nuclei from 21-day gestational age fetal rabbits suggests that the SP-A gene may exist in an accessible conformation prior to the time of transcription initiation.

MHC-restricted responses of CD8+ and CD4+ T-cell clones from regional lymph nodes of melanoma patients

Regional lymph-node (LN) lymphocytes may constitute an important defence against the spread of human melanoma beyond regional LNs. The present study was directed to clonal analysis of lymphocytes cultured either directly from the LNs or after stimulation in cultures with autologous melanoma (MLTC). T-cell clones derived from MLTC reactions had either CD4+ or CD8+ phenotypes. Inhibition studies with monoclonal antibodies (MAbs) suggested that the CD8+ cytotoxic T-cell (CTL) clones had MHC-class-I-restricted cytotoxic activity against the autologous and a proportion of HLA-class-I-compatible allogeneic melanomas. The pattern of cytotoxicity against a panel of HLA-typed melanoma cells and inhibition by (polyclonal) HLA-typing sera suggested the CD8+ CTL were restricted by HLA-A3. The CD4+ T-cell clones had weak cytotoxic activity which appeared restricted by HLA-DR2. T cells cultured from unstimulated lymphocytes were all CD4+. One of the clones exhibited cytotoxic activity against both the autologous and HLA-DR2-compatible allogeneic melanoma cells, whereas another 2 had cytotoxic activity only against a HLA-DR2-compatible allogeneic melanoma established from a primary melanoma. IL-2 production by a 4th non-cytotoxic clone had similar specificity. These results suggest that HLA-A3 and DR2 may act as restricting elements in recognition of melanoma antigens by T cells from LNs and that they may have recognized at least 2 different antigens on the melanoma cells.