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.

Domains of type X collagen: alteration of cartilage matrix by fibril association and proteoglycan accumulation

During endochondral bone formation, hypertrophic cartilage is replaced by bone or by a marrow cavity. The matrix of hypertrophic cartilage contains at least one tissue-specific component, type X collagen. Structurally type X collagen contains both a collagenous domain and a COOH-terminal non-collagenous one. However, the function(s) of this molecule have remained largely speculative. To examine the behavior and functions of type X collagen within hypertrophic cartilage, we (Chen, Q., E. Gibney, J. M. Fitch, C. Linsenmayer, T. M. Schmid, and T. F. Linsenmayer. 1990. Proc. Natl. Acad. Sci. USA. 87:8046-8050) recently devised an in vitro system in which exogenous type X collagen rapidly (15 min to several hours) moves into non-hypertrophic cartilage. There the molecule becomes associated with preexisting cartilage collagen fibrils. In the present investigation, we find that the isolated collagenous domain of type X collagen is sufficient for its association with fibrils. Furthermore, when non-hypertrophic cartilage is incubated for a longer time (overnight) with "intact" type X collagen, the molecule is found both in the matrix and inside of the chondrocytes. The properties of the matrix of such type X collagen-infiltrated cartilage become altered. Such changes include: (a) antigenic masking of type X collagen by proteoglycans; (b) loss of the permissiveness for further infiltration by type X collagen; and (c) enhanced accumulation of proteoglycans. Some of these changes are dependent on the presence of the COOH-terminal non-collagenous domain of the molecule. In fact, the isolated collagenous domain of type X collagen appears to exert an opposite effect on proteoglycan accumulation, producing a net decrease in their accumulation, particularly of the light form(s) of proteoglycans. Certain of these matrix alterations are similar to ones that have been observed to occur in vivo. This suggests that within hypertrophic cartilage type X collagen has regulatory as well as structural functions, and that these functions are achieved specifically by its two different domains.

Activation of the growth arrest and DNA damage-inducible gene gadd 153 by nephrotoxic cysteine conjugates and dithiothreitol

The cellular and biochemical events which transduce chemical insults into signals for increased expression of the stress-responsive gene gadd 153 were investigated using nephrotoxic cysteine conjugates. In LLC-PK1 cells, cysteine conjugate toxicity is initiated by covalent binding, but depletion of cellular thiols, an increase in cytosolic free calcium, and lipid peroxidation couple the binding to cell death (Chen, Q., Jones, T. W., Brown, P. C., and Stevens, J. L. (1990) J. Biol. Chem. 265, 21603-21611; Chen, Q., Jones, T. W., and Stevens, J. L. (1991) Toxicologist 11, 101, 1991). Three different toxic cysteine conjugates induced gadd 153 mRNA. With S-(1,2-dichlorovinyl)-L-cysteine (DCVC), the induction was both concentration and time-dependent. Preventing the metabolism of DCVC and covalent binding of DCVC-derived reactive metabolites to cellular macromolecules with the beta-lyase inhibitor (aminooxy)acetic acid blocked the induction. However, buffering free calcium with a cell permeable calcium chelator or blocking lipid peroxidation with an antioxidant did not affect the induction of gadd 153 mRNA by DCVC even though these treatments inhibit toxicity. These data suggest that covalent binding of reactive metabolites to cellular macromolecules may serve as a primary signal for the induction of gadd 153 mRNA by nephrotoxic cysteine conjugates. Interestingly, the sulfhydryl agent dithiothreitol, which was nontoxic and prevented the toxicity of DCVC, also induced an increase in gadd 153 mRNA. When both dithiothreitol and DCVC were added to cells, there were no inhibitory or additive effects on expression. Therefore, cellular thiol-disulfide status may also play a role in gadd 153 induction.

[Chemical studies on immunologically active polysaccharides of Ganoderma lucidum(Leyss. ex Fr.) Karst]

BN3B, the polysaccharide component of the fruit of Ganoderma lucidum, has been shown to have immune activity. From BN3B four homogeneous polysaccharides were separated and purified. Chemical studies on the main components BN3B1 and BN3B3 indicated that BM3B1 contained only glucose and should be a glucan containing beta-(1----6) and (1----3)glycoside bonds and that BN3B3 was an arabinogalactan containing beta-(1----6) and (1----3)glycoside bonds.

Expression and transport of rabbit surfactant protein A in COS-1 cells

SV40-transformed green monkey kidney (COS-1) cells were transfected with expression plasmids that contained either the structural gene or cDNA for surfactant protein A (SP-A), a major protein of rabbit lung surfactant. The transfected COS-1 cells synthesized several isoforms of SP-A that were found to be less acidic than those produced in rabbit lung tissue. SP-A species with apparent molecular weight (M(r)) approximately equal to 29,000-33,000 were detected in the transfected cells, whereas glycosylated forms with apparent M(r) approximately equal to 33,000-38,000 were detectable only in the culture medium. Analysis of transfected cells by indirect immunofluorescence revealed that SP-A was localized in punctate bodies throughout the cytoplasm. Expressed SP-A was not detectable on the cell surface nor was there evidence that secreted SP-A was endocytosed by COS-1 cells. After subcellular fractionation of the transfected COS-1 cells, SP-A was found to be localized predominantly in the 5,000- and 18,000-g pellet fractions; little or no immunoreactive SP-A was detectable in cytosolic fractions. Treatment of transfected cells with the glycosylation inhibitor tunicamycin prevented secretion of SP-A into the medium, suggesting a role of glycosylation in secretion of SP-A. On the other hand, treatment of transfected cells with inhibitors of proline hydroxylation, which may cause destabilization of the collagen-like domain of SP-A, reduced but did not prevent secretion of SP-A into the culture medium.(ABSTRACT TRUNCATED AT 250 WORDS)

The superficial buffer barrier in vascular smooth muscle

Force development and fura-2 fluorescence were simultaneously measured in the rabbit inferior vena cava. Discharging SR Ca2+ with either caffeine or norepinephrine prior to stimulation of Ca2+ influx induced a delay of 30-70 s between the intracellular Ca2+ signal and development of force. This delay was abolished by the application of caffeine. These data support the superficial buffer barrier hypothesis, which holds that Ca2+ entry from the extracellular space proceeds via a restricted cytoplasmic region between the inner plasmalemmal surface and the peripheral sarcoplasmic reticulum (SR). Ca2+ accumulation by this SR fraction appears to be able to delay Ca2+ entry into the deeper myoplasm where it activates the myofilaments. Caffeine and thapsigargin elevated the steady-state [Ca2+]i, suggesting a contribution by the SR Ca2+ pump to Ca2+ extrusion from the cells. Norepinephrine enhanced myofilament Ca2+ sensitivity, while caffeine decreased it.

Targeting of «T» Lymphocytes against Human Hepatoma Cells by a Bispecific Monoclonal Antibody: Role of Different Lymphocyte Subsets

In an attempt to construct bispecific monoclonal antibodies (bimAbs) able to target cytotoxic T lymphocytes against human hepatoma cells, an HGPRT-deficient mutant of the Hepama-6 hybridoma, which produces an antihuman-hepatoma mAb, was directly fused with splenocytes from Balb/C mice immunized by a polyclonal cytotoxic T-cell line. Hybrid hybridomas were selected in HAT medium, and their supernatants were directly screened for the ability to induce IL-2-cultured cytotoxic T lymphocytes to kill hepatoma cells in a 51Cr-release assay. The selected hybrid hybridoma, termed DQ-33, secretes a bimAb, which reacts with a CD3-associated determinant. When resting peripheral-blood lymphocytes were used as effector cells, virtually no cytolytic activity could be induced by DQ-33, whereas phytohemagglutinin-activated lymphocytes that had been expanded in vitro in IL-2-containing medium could be efficiently targeted against hepatoma cells. Targeting by DQ-33 bimAb was analyzed on different subsets of IL-2-cultured lymphocytes. It was evident that CD+4–8+ TCRα/β+ and CD3+4–8-TCRγ/δ+ lymphocytes were efficiently induced by bimAb to lyse human hepatoma cells, whereas no induction of cytolysis could be observed when CD3 + 4+8-TCRα/β+ cells were used as effectors. DQ-33 bimAb was also able to induce lymphokine secretion (IL-2, GM-CSF and TNF-α) by all the different subsets of lymphocytes analyzed in the presence of target cells expressing the relevant antigen, independent of the expression of cytolytic activity.

[A preliminary study of the chord and specific time constants in 342 healthy children]

Using Knudson's method, the chord time constant, tau ch, tau ch75, tau ch50, tau ch25, and specific time constant, S tau, 1/V75, 1/V50, 1/V25, at high, middle and low lung volumes were calculated from V75, V50 and V25 of the MEFV curves measured previously from 342 healthy children of 3-6 years of age in a nursery. The multiple stepwise regression equation were built with age, height and FVC as independent variables by the IBM-XT/PC computer. The result showed that the S tau corrected by volume from tau ch could reflect the time required for change of unit lung volume more precisely than tau ch owing to the elimination of the influence of lung volume. The S tau was shortened with the increase of age, and was negatively correlate with age and FVC. These facts reflected the growth of lung elastic pressure (PLel) and airway conductance (Gaw) with the increase of age. The prolongation of S tau with the decay of lung volume just reflected the decrease of PLel and Gaw with the decay of lung volume. No regular changes of tau h were observed with age and lung volume. Probably, it was concerned with the complexity of factors affecting the tau ch.

Digital subtraction angiography in the preoperative diagnosis of congenital heart disease

From December of 1986 through February of 1990, digital subtraction angiography was performed on 156 patients, and specific diagnoses of congenital heart disease were made on the basis of information gathered by this imaging technique, supplemented by the physical examination. No other imaging techniques were used, for this was a prospective study designed to determine the accuracy of digital subtraction angiography alone in the diagnosis of congenital heart disease. When 80 of these 156 patients underwent subsequent operation, 75 were shown to have been diagnosed correctly, for an accuracy rate of 93.75%. Two patients died, for a mortality rate of 2.5%. The diagnostic value of digital subtraction angiography is discussed, as well as the compensative management of its artifacts.

Transferrin subtypes in 11 south China minority populations

Transferrin subtypes were determined by isoelectric focussing (IEF) in a total of 2,121 individuals from 11 South China minority populations. The C1, C2 and DCHI alleles were present in all the populations; B alleles were lacking, C4 was found in 3 populations and C3 in 6. C2 and C4 allele frequencies are notable in these minority groups. The frequency of the C2 allele was higher (0.25-0.38) than that of Han Chinese (0.18-0.25). In Bai the C2 frequency was as high as 0.38. The C4 allele was present at a low frequency (less than 0.01), which suggests that this allele probably existed in the ancestral Mongoloid population at a low frequency and increased in frequency in Amerindians due to genetic drift or other factors.

Irreversible inactivation of diacylglycerol kinase-II requires a mediator

Cytosolic diacylglycerol kinase was irreversibly inactivated by 5'-AMP since the enzyme remained less active after the removal of 5'-AMP by P-10 gel chromatography. The inactivation was time-dependent, suggesting the involvement of a covalent bond modification. A reconstitution experiment detected a rat brain cytosolic mediator for the effect of 5'-AMP. A protein kinase rich fraction prepared from rat liver was also capable of restoring the sensitivity of diacylglycerol kinase-II to 5'-AMP. We propose that 5'-AMP-activated protein kinase is the mediator which inactivates diacylglycerol kinase-II, possibly by phosphorylation.

Magnetic fields associated with anoxic depolarization in anesthetized rats

We have performed simultaneous measurements of the DC-magnetoencephalogram (DC-MEG) and DC-electrocorticogram (DC-ECoG) in rats (n = 6) subjected to 90 s of reversible anoxia. The onset of major shifts of electric and magnetic signals occurred at 52 +/- 18 (S.D.) and 68 +/- 14 (S.D.), respectively, and reached a peak at 83 +/- 27 and 102 +/- 19 (S.D.) s, respectively, after termination of mechanical ventilation. DC-ECoG signal deflections were always associated with DC-MEG deflections. The time of onset and peak signals in both DC-MEG and DC-ECoG changes caused by asphyxia were highly correlated (r + 0.83, 0.94; P less than 0.05, 0.001; respectively). Our observations suggest that the non-invasive technique of DC-MEG is reliable and may provide insight into the mechanisms of anoxic cerebral depolarization.

[Determination of the partial mean transit time with "convenient calculation" in young children]

A "convenient calculation" of MTTp = 0.1 FVC/2 Vp was derived from the principle of Jordanoglou to measure the partial mean transit time (MTTp). It was used to calculate the MTTp from the maximal expiratory flow volume (MEFV) curve of 342 healthy young children. The multiple regression equations were built with age, height and FVC as independent variables. The result showed that the MTTp of all children were elongated with the decay of lung volume with a similar rule as in the old, middle-aged and young people. No regular changes of MTTp in age groups were noticed. The regression equations showed that the MTTp of boys were positively correlated with FVC; while those of girls were negatively correlated with age; besides, MTT20-30% and MTT70-80% were positively correlated with FVC. The age and FVC just had the opposite effects so that little regular changes of MTTp occurred in the age groups.

Enhancer-binding activity of the tal-1 oncoprotein in association with the E47/E12 helix-loop-helix proteins

Almost 30% of patients with T-cell acute lymphoblastic leukemia (T-ALL) bear structural alterations of tal-1, a presumptive proto-oncogene that encodes sequences homologous to the helix-loop-helix (HLH) DNA-binding and dimerization domain. Analysis of the tal-1 gene product reveals that its HLH domain mediates protein-protein interactions with either of the ubiquitously expressed HLH proteins E47 and E12. The resultant tal-1/E47 and tal-1/E12 heterodimers specifically recognize the E-box DNA sequence motif found in eucaryotic transcriptional enhancers. Hence, the tal-1 protein shares biochemical properties with other tissue-specific HLH proteins that control cell type determination during myogenesis (e.g., MyoD1) and neurogenesis (e.g., achaete-scute). The data suggest that HLH heterodimers involving tal-1 may function in vivo as transcriptional regulatory factors that influence cell type determination during hematopoietic development.

Bispecific monoclonal antibodies directed to CD16 and to a tumor-associated antigen induce target-cell lysis by resting NK cells and by a subset of NK clones

CD16 surface antigens represent activatory molecules in CD3-16+ NK cells. In order to target NK cells against relatively NK-resistant ovarian carcinomas, we used an anti-CD16 monoclonal antibody (MAb) (VD4), together with an anti-ovarian carcinoma-associated antigen (MOV19), to construct biMAbs. To this end, hybrid hybridomas were generated by fusing a TK-deficient VD4 hybridoma mutant with a HGPRT-deficient MOV19 hybrid. Supernatants from hybrid hybridomas that had been selected in HAT medium were screened for their ability to induce a CD3-16+ NK clone to lyse an MOV19+ ovarian carcinoma cell line in a 4-hr 51Cr-release assay. The NMB.45 hybrid hybridoma secreted a biMAb which triggered lysis of MOV19+ but not of MOV19- target cells. Some degree of target cell lysis was also observed with MOV19 MAb (due to ADCC mechanisms), while the VD4 MAb was ineffective. HPLC fractionation of MAbs secreted by the hybrid hybridoma made it possible to identify 4 different peaks, one of which appeared to contain functional biMAb molecules. HPLC-purified biMAb (100 ng/ml) induced resting PBL to lyse the "NK-resistant" IGROVI ovarian carcinoma cell line. Fresh MOV19+ tumor cells were also lysed, although with lower efficiency. When IL-2-activated lymphocytes were used as a source of effectors, biMAb caused only minor increases in the IL-2-induced cytolytic activity. Further analyses of the effect of biMAb were performed at the clonal level. Among CD3-16+ NK cell clones, a clear enhancing effect could be observed only in GL183+ but not in GL183- clones. In CD3+ cytotoxic clones a triggering effect could be detected in one out of 4 TCR gamma/delta+ clones but not in TCR alpha/beta+ clones.

Regulation of chylomicron remnant uptake in the human hepatoma cell-line Hep G2. Role of the low-density lipoprotein receptor

Uptake and degradation of chylomicron remnants by the human hepatoma cell line Hep G2 was studied. Mesenteric lymph was collected from rats and injected into hepatectomized rats to obtain chylomicron remnants. This remnant preparation was taken up and catabolized by Hep G2 cells. The uptake process was dependent on cell growth and was regulated by compactin (a HMG-CoA reductase inhibitor) which suppresses cholesterol synthesis and by mevalonolactone, which enhances cholesterol synthesis. A monoclonal anti LDL receptor antibody blocked binding of chylomicron remnants to Hep G2 cells to a degree, which was comparable to but generally lower than the suppression of low-density lipoprotein binding. The results thus indicate that in Hep G2 cells, chylomicron remnant uptake is regulated, similarly to low-density lipoprotein uptake and that a significant part of the remnant uptake is mediated through the LDL receptor.

Neomycin inhibits the phosphatidylinositol monophosphate and phosphatidylinositol bisphosphate stimulation of plasma membrane ATPase activity

The inositol phospholipids, phosphatidylinositol monophosphate (PIP) and phosphatidylinositol bisphosphate (PIP(2)), have been shown to increase the vanadate-sensitive ATPase activity of plant plasma membranes (AR Memon, Q Chen, WF Boss [1989] Biochem Biophys Res Commun 162: 1295-1301). In this paper, we show the effect of various concentrations of phosphatidyinositol, PIP, and PIP(2) on the plasma membrane vanadate-sensitive ATPase activity. PIP and PIP(2) at concentrations of 10 nanomoles per 30 microgram membrane protein per milliliter of reaction mixture caused a twofold and 1.8-fold increase in the ATPase activity, respectively. The effect of these negatively charged phospholipids on the ATPase activity was inhibited by adding the positively charged aminoglycoside, neomycin. Neomycin did not affect the endogenous plasma membrane ATPase activity in the absence of exogenous lipids.

Analysis of conserved domains identifies a unique structural feature of a chloroplast heat shock protein

A low molecular weight heat shock protein which localizes to chloroplasts has been identified in several plant species. This protein belongs to a eukaryotic superfamily of small HSPs, all of which contain a conserved carboxyl-terminal domain. To investigate further the structure of this HSP, we isolated and sequenced cDNA clones for the chloroplast LMW HSPs from Petunia hybrida and Arabidopsis thaliana. The cloning of chloroplast HSPs from these two species enabled us to compare the amino acid sequences of this protein from plant species (petunia, Arabidopsis, pea, soybean and maize) that represent evolutionarily divergent taxonomic subclasses. Three conserved regions were identified, which are designated as regions I, II and III. Regions I and II are also shared by cytoplasmic LMW HSPs and therefore are likely to have functional roles common to all eukaryotic LMW HSPs. In contrast, consensus region III is not found in other LMW HSPs. Secondary structure analysis predicts that this region forms an amphipathic alpha-helix with high conservation of methionine residues on the hydrophobic face and 100% conservation of residues on the hydrophilic face. This structure is similar to three helices, termed "methionine bristles", which are found in a methionine-rich domain of a 54 kDa protein component of signal recognition particle (SRP54). The conservation of regions I and II among LMW cytoplasmic and chloroplast HSPs suggests that these HSPs perform related functions in different cellular compartments. However, identification of the methionine bristle domain suggests that chloroplast HSPs also have unique functions or substrates within the special environment of the chloroplast or other plastids.

The relationship between hepatic low-density lipoprotein receptor activity and serum cholesterol level in the human fetus

We found that the binding of 125I-low-density lipoprotein to fetal liver low-density lipoprotein receptor rose progressively with the increase in fetal age. During this period, total cholesterol and low-density lipoprotein-cholesterol levels in fetal serum declined significantly. The correlation coefficients between fetal age and concentration of serum total cholesterol and low-density lipoprotein cholesterol were -0.80 (p less than 0.001) and -0.77 (p less than 0.001), respectively. A significant inverse correlation also existed between the liver low-density lipoprotein receptor activity and the serum total cholesterol (r = -0.96, p less than 0.001) and low-density lipoprotein cholesterol (r = -0.95, p less than 0.001) but not high-density lipoprotein cholesterol. It is suggested that the low-density lipoprotein receptors in human fetal liver may play a key role in the regulation of the serum cholesterol levels during gestation.

[Effects of SC1001-sodium on hippocampal kindled seizures by coriaria lactone in rabbits]

Healthy rabbits weighing 1.7-2.4 kg were used. According to Sawyer's atlas the stainless steel cannula and recording electrode were implanted into the left hippocampus of each animal. The kindling experiments were started one week after the surgical operation. For kindling, all animals received injection of 2 microliters of diluted solution containing 0.55 or 0.32 microgram of coriaria lactone (CL) every second day, through the single stainless steel cannula previously implanted in the hippocampus. Hippocampal EEG of all the animals was recorded by telemetric method and the behavior of them was observed at the same time. Eighteen fully kindled rabbits were separated into three groups. The SC1001 Na group of six rabbits was treated with SC1001 Na (100 mg/kg, i.m.), the PB Na group (six rabbits) received phenobarbital Na (30 mg/kg, i.m.), and the control group of six was treated with placebo (normal saline, i.m., in the same volume as that of the SC1001 Na injection); injections were administered once a day for two courses of treatment (one course of treatment was 1 week). The results of the experiment indicated that SC1001 Na (100 mg/kg) had certain effects on hippocampal kindled seizures induced by CL, but its curative effects were not more notable than those of PB Na (30 mg/kg).

Histopathological, cytogenetic, and molecular characterization of renal cortical tumors

We used cytogenetic and restriction fragment length polymorphism (RFLP) analysis methods to define genetic alterations and also correlate the changes with histopathology in renal cortical tumors. The study series is comprised of 50 renal tumors in 4 histological categories: (a) clear cell, nonpapillary, renal cell carcinoma (RCC) (n = 32); (b) nonclear cell, nonpapillary RCC (n = 10); (c) papillary RCC (n = 3); and (d) oncocytic tumors (n = 5). Successful karyotypes were obtained from 28 tumors (56%), of which 17 (61%) were abnormal. Abnormalities of chromosome 3p were seen in 9 tumors, which included unbalanced translocations and terminal or interstitial deletions. Abnormalities of chromosome 5 were identified in 11 tumors, 8 of which were due to unbalanced translocations between 3p and 5q, resulting in an extra copy for the region 5q22----ter. In addition, trisomy or tetrasomy of chromosome 17 was seen in 6 (5 with normal chromosome 3 and one with 3p deletion), trisomy or more copies of chromosome 7 in 8 (4 with 3p deletion, 2 with trisomy or tetrasomy 17, and 2 with trisomy alone), and trisomy 12 in 3 (all with trisomy 17) tumors. Furthermore, relative deficiency of chromosome 17p was seen in 3 (all with deletion 3p) and chromosome 18 in 4 (all with deletion 3p) tumors. RFLP analysis with four chromosome 3 specific probes detected 3p deletions in 19 tumors with the most common breakpoint located between 3p14-21. The 19 3p deletions detected by RFLP included tumors that also showed rearrangement of 3p by cytogenetics (n = 4) and those that showed normal karyotypes (n = 3) in addition to cytogenetic failures (n = 12). Deletions of 17p were seen in 5 of 31 informative cases. Thus, deletions of 3p were seen in a total of 24 tumors by cytogenetic and/or RFLP analysis, 21 of which were clear cell, nonpapillary RCC, whereas 3 had a minor clear-cell component. Oncocytic and nonclear, nonpapillary tumors, on the other hand, did not demonstrate 3p deletions by either technique, whereas trisomy 17 was seen in 3 of the 3 papillary tumors. The loss of alleles from chromosome 17p and 18 and an increased dosage of gene or genes on chromosomes 5q and 7 as seen in high-stage tumors of various histological subtypes may be associated with progression of disease.

Inhibition of iodoacetamide and t-butylhydroperoxide toxicity in LLC-PK1 cells by antioxidants: a role for lipid peroxidation in alkylation induced cytotoxicity

Previously we reported that thiol depletion and lipid peroxidation were associated with the cytotoxicity of nephrotoxic cysteine S-conjugates, a group of toxins which kill LLC-PK1 cells after metabolic activation and covalent binding. To determine if this is a general mechanism of cytotoxicity in these cells, we compared the effect of antioxidants, an iron chelator, and a thiol reducing agent on the toxicity of an alkylating agent, iodoacetamide (IDAM), and an organic peroxidant, t-butylhydroperoxide (TBHP). IDAM or TBHP toxicity was concentration (0.01 to 1.0 mM) and time (1 to 6 h) dependent. Both toxins caused lipid peroxidation which occurred prior to cell death as determined by leakage of lactate dehydrogenase (LDH). The alkylating agent IDAM bound to cellular macromolecules and depleted cellular non-protein thiols almost completely by 1 h, while LDH release occurred first at 2 to 3 h. The toxicity of IDAM and TBHP was inhibited by the antioxidants DPPD, BHA, BHQ, PGA, and BHT and the iron chelator deferoxamine. However, DPPD blocked TBHP- and IDAM-induced lipid peroxidation and toxicity without affecting binding and depletion of cellular nonprotein thiols. Furthermore, the thiol reducing agent dithiothreitol was able to block lipid peroxidation and toxicity. Therefore it is possible that with an alkylating agent, depletion of cellular nonprotein thiols cooperates with covalent binding and contributes to lipid peroxidation and cell death. There appear to be common elements in the toxicity of alkylating agents and organic peroxidants in LLC-PK1 cells.

Induction of synaptic development in cultured muscle cells by basic fibroblast growth factor

The role of basic fibroblast growth factor (bFGF) in signaling the development of the neuromuscular junction was examined. Beads coated with bFGF induced the formation of acetylcholine receptor (AChR) clusters in cultured Xenopus myotomal muscle cells. Tyrphostin, a tyrosine kinase inhibitor, abolished AChR clustering induced by bFGF beads, suggesting a role of tyrosine kinase activation in AChR clustering. Using specific antibodies, we demonstrated the presence of both bFGF and its receptor in the myotomal muscle in vivo during the period of neuromuscular connection. However, similar tissue from older animals with mature neuromuscular junctions showed an apparently truncated form of the bFGF receptor. These data suggest that bFGF may play a role in signaling synaptogenesis in skeletal muscle.

[Effect of pulsed electromagnetic field on orthodontic tooth movement through transmission electromicroscopy]

This experiment is to observe the effect of pulsed electromagnetic field (PEMF) on orthodontic tooth movement of guinea pigs through transmission electron microscope (TEM). 14-days observations indicate that PEMF could accelerate the rate of orthodontic tooth movement as a result of the increase in quantity of active cell without changing the ultrastructures of cells and have no unfavorable effects on periodontal tissues.

The mechanism of cysteine conjugate cytotoxicity in renal epithelial cells. Covalent binding leads to thiol depletion and lipid peroxidation

Nephrotoxic cysteine conjugates kill cells after they are metabolized by the enzyme cysteine conjugate beta-lyase to reactive fragments which bind to cellular macromolecules. We have investigated the cellular events which occur after the binding and lead ultimately to cell death in renal epithelial cells. Using S-(1,2-dichlorovinyl)-L-cysteine (DCVC) as a model conjugate, we found that the phenolic antioxidants N,N'-diphenyl-p-phenylenediamine (DPPD), butylated hydroxyanisole, butylated hydroxytoluene, propyl galate, and butylated hydroxyquinone, and the iron chelator deferoxamine inhibited the cytotoxicity significantly. Among the five antioxidants, DPPD was most potent. DPPD blocked DCVC toxicity over an extended time period, and the rescued cells remained functional as measured by protein synthetic activity. DPPD was able to block the toxicity of two other toxic cysteine conjugates S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine and S-(1,1,2,2-tetrafluoroethyl)-L-cysteine. In addition to LLC-PK1 cells, DPPD also protected freshly isolated rat kidney epithelial cells in suspension and in primary culture. In suspension cells, DPPD was effective at low doses of DCVC (25-50 microM) but not at high concentrations (250-500 microM). DPPD inhibition was not due to an inactivation of beta-lyase or a decrease in the binding of [35S]DCVC metabolites to cellular macromolecules and occurred at a step after the activation of the toxins. During DCVC treatment, lipid peroxidation products were detectable prior to cell death. DPPD blocked lipid peroxidation over the whole time course. Depletion of nonprotein thiols also occurred prior to cell death. DPPD did not prevent the loss of nonprotein thiols. However, the sulfhydryl-reducing agent DTT blocked lipid peroxidation and toxicity at a step after the activation of DCVC. Therefore, it appears that cysteine conjugates kill renal epithelial cells by a combination of covalent binding, depletion of nonprotein thiols, and lipid peroxidation.

Short-term treatment with cell wall degrading enzymes increases the activity of the inositol phospholipid kinases and the vanadate-sensitive ATPase of carrot cells

Treating carrot (Daucus carota L.) suspension culture cells with a mixture of cell wall degrading enzymes, Driselase, resulted in an increase in the percentage of [(3)H]phosphatidylinositol bisphosphate. Analysis of the lipid kinase activities in the isolated plasma membranes after whole cell treatment indicated that treatment with Driselase (2% weight/volume; the equivalent of 340 units per milliliter of hemicellulase and 400 units per milliliter of cellulase activity) or treatment with hemicellulase (31.7% weight/volume, 20.7 units per milliliter) resulted in an increase in the inositol phospholipid kinase activity. However, treatment with cellulase alone had no effect at 0.5% (weight/volume, 17.2 units per milliliter) or inhibited the kinase activity at 1% (weight/volume, 34.4 units per milliliter). The active stimulus in Driselase was heat sensitive. The plasma membrane vanadate-sensitive ATPase activity also increased when the cells were treated with Driselase. A time course study indicated that both the inositol phospholipid kinases and the plasma membrane vanadate-sensitive ATPase responded to as little as 5 seconds of treatment with 2% Driselase. However, at the lowest concentration of Driselase (0.04%, weight/volume) that resulted in an increase in inositol phospholipid kinase activity, the ATPase activity was not affected. Because inositol phospholipids have been shown to activate the vanadate-sensitive ATPase from plants (AR Memon, Q Chen, WF Boss [1989] Biochem Biophys Res Commun 162: 1295-1301), a stimulus-response pathway involving both the inositol phospholipid kinases and the plasma membrane vanadate-sensitive ATPase activity is discussed.