Biomedical subjects

A Yoshida

Publications and source records attributed to A Yoshida.

At least 19 recordsLinked to original sources

PubMed1992

HPC-1 is associated with synaptotagmin and omega-conotoxin receptor.

Monoclonal antibodies were produced that recognize a membrane protein of 35,000 Da (p35) expressed in brain and adrenal medulla. They immunoprecipitated 50% of omega-conotoxin (omega-CgTX) receptor, a putative N-type calcium channel, solubilized from rat brain. Anti-synaptotagmin (p65) antibodies also immunoprecipitate omega-CgTX receptor (Leveque, C., Hoshino, T., David, P., Shoji-Kasai, Y., Leys, K., Omori, A., Lang, B., El Far, O., Sato, K., Martin-Moutot, N., Newsom-Davis, J., Takahashi, M., and Seagar, M.J. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 3625-3629); however, immunoprecipitation by anti-p35 antibodies and anti-synaptotagmin antibodies was not additive. Furthermore, both p35 and synaptotagmin were recovered in the immunoprecipitates with anti-synaptotagmin and anti-p35 antibodies, respectively, indicating that a population of omega-CgTX receptor exists as a ternary complex with synaptotagmin and p35. A cDNA coding p35 was isolated from a rat brain cDNA library by immuno-screening, and the primary structure of the protein was revealed to be identical to that of HPC-1 (Inoue, A., Obata, K., and Akagawa, K. (1992) J. Biol. Chem. 267, 10613-10619). HPC-1 has a putative transmembrane segment at the C terminus and four heptad motifs, which may be involved in protein-protein interaction. These results suggest that HPC-1 may play a role in neurotransmitter release from nerve terminals by associating with omega-CgTX-sensitive N-type calcium channel and synaptotagmin.

Amino Acid Sequence↗

PubMed1992

Structural differences between heparan sulphates of proteoglycan involved in the formation of basement membranes in vivo by Lewis-lung-carcinoma-derived cloned cells with different metastatic potentials.

This study addresses the characterization of heparan sulphates of the basement-membrane proteoglycans in tumour formed after the subcutaneous implantation of Lewis-lung-carcinoma-derived different metastatic clones (P29, LM12-3 and LM60-D6 clones with low, medium and high metastatic potentials respectively). Heparan sulphate proteoglycans (125-158 micrograms of hexuronate/g dry weight of tissue) were isolated from chondroitin ABC lyase digests of a proteoglycan fraction obtained after DEAE-Sephacel chromatography of tissue extracts. The proteoglycans were separated into three molecular species by Sepharose CL-4B chromatography followed by CsCl-density-gradient centrifugation: large proteoglycans with an estimated M(r) of 820,000-130,000, which consisted of two components with low (< 1.34 g/ml; PGII-M) and high (> 1.37 g/ml; PGII-B) density, and a small proteoglycan with an M(r) of less than 80,000 (PGIII). Of these, only the PGII-M proteoglycan (34-37 micrograms of hexuronate/g dry weight) reacted with the antiserum against proteoglycan of Engelbreth-Holm-Swarm-tumour basement membrane, and represented, therefore, a basement-membrane proteoglycan. Digestion with heparan sulphate lyases I and II of the heparan sulphates (M(r) 36,000) from the PGII-M proteoglycan of the three tumours resulted in almost complete depolymerization to give six unsaturated disaccharides identified as 2-acetamido-2-deoxy-4-O-(4-deoxy-alpha-L-threo-hex-4-enopyranosyluron ic acid)-D-glucose, 2-acetamido-2-deoxy-4-O-(4-deoxy-alpha-L-threo-hex-4-enopyranosyluron ic acid)-6-O-sulpho-D-glucose, 2-deoxy-2-sulphamino-4-O-(4-deoxy-alpha-L-threo-hex-4-enopyrano syluronic acid)-D-glucose, 2-deoxy-2-sulphamino-4-O-(4-deoxy-alpha-L-threo-hex-4-enopyrano syluronic acid)-6-O-sulpho-D-glucose, 2-deoxy-2-sulphamino-4-O-(4-deoxy-2-O-sulpho-alpha-L-threo-hex-4- enopyranosyluronic acid)-D-glucose and 2-deoxy-2-sulphamino-4-O-(4-deoxy-2-O-sulpho-alpha-L-threo-hex-4- enopyranosyluronic acid)-6-O-sulpho-D-glucose. Comparison of the relative amounts of these disaccharides produced from the three tumour-derived heparan sulphates demonstrated that the degree of sulphation of the heparan sulphates correlated with the degree of morphological organization of the tumour basement membranes; the heparan sulphate from the more highly metastatic tumour with more highly organized basement membrane exhibited a higher degree of overall sulphation along the glycosaminoglycan chains, which was due to an increased content of the three repeating disaccharides having 6-O-sulphated glucosamine residues.

Animals↗

PubMed1992

Differential effect of vasoactive intestinal peptide, somatostatin, and substance P on human IgE and IgG subclass production.

We studied the effect of vasoactive intestinal peptide (VIP), somatostatin (SOM), and substance P (SP) on IL-4-stimulated human IgE and IgG subclass production. VIP and SOM, but not SP, inhibited IgE production without affecting IgM or IgA production by mononuclear cells (MNC) from nonatopic donors from 10 pM to 10 nM. These neuropeptides also differentially modulated IgG subclass production. While IgG1 production was not affected by VIP, SOM, or SP, all of the neuropeptides enhanced IgG2 production. By contrast, SOM and SP, but not VIP, inhibited IgG3 production, whereas VIP and SP, but not SOM, enhanced IgG4 production. The effect by neuropeptides was specific since each peptide effect was specifically blocked by each antagonist. To achieve this effect, neuropeptides must be added at the start of the culture and be present throughout the entire culture period. The inhibition of IgE production was not mediated by known inhibitors of IgE production, IFN-gamma or PGE2, because the addition of anti-IFN-gamma mAb (10 micrograms/ml) or indomethacin (0.1 microM) did not overcome the inhibition of IgE production. In contrast to MNC, neuropeptides did not affect IgG subclass production in purified B cells. IgE production was not induced by IL-4 in purified B cells. Neuropeptides also failed to modulate IgG subclass production in cultures of B cells with either T cells or monocytes. However, they modulated IgE production and IgG subclass production in B cells in the presence of T cells and monocytes. In purified B cells, IL-4 plus anti-CD40 mAb induced IgE production which was not inhibited by VIP or SOM. However, VIP or SOM, but not SP, inhibited IgE production in B cells cultured with both T cells and monocytes. Finally, the mechanism of modulation of IgE and IgG4 production was dependent on IL-4-induced switching, since neuropeptides modulated IgG4 and IgE production in surface IgG4-negative (sIgG4-) and sIgE- B cells, respectively. In contrast, modulation of IgG2 and IgG3 production was not due to switching, since neuropeptides did not affect either IgG2 or IgG3 production in sIgG2- or sIgG3- B cells, respectively.

Cells, Cultured↗

PubMed1992

The afferent and efferent connections of the nucleus submedius in the rat.

The afferent and efferent connections of the nucleus submedius (Sm) in the medial thalamus of the rat were examined. Injections of wheat-germ agglutinin conjugated horseradish peroxidase (WGA-HRP) into the Sm resulted in dense terminal labeling in the middle layers of the ipsilateral ventrolateral orbital cortex (VLO). Less dense labeling was also observed in the superficial and deep layers of VLO and in the medial part of the lateral orbital cortex (LO) and in the contralateral VLO. Retrogradely labeled neurons were observed primarily in the deep layers of VLO and the dorsal peduncular cortex (DP). Labeled neurons were also observed bilaterally, in the nucleus of the horizontal limb of the diagonal band, the lateral hypothalamus, the thalamic reticular nucleus (Rt), medial parabrachial nucleus (MPB), and the laterodorsal tegmental nucleus (LDT). Many labeled neurons were also observed in the trigeminal brain-stem complex. Injections of Fluoro-Gold (FG) into Sm resulted in a very similar distribution of retrogradely labeled neurons. Injections of WGA-HRP and FG in the orbital cortex confirmed the ipsilateral Sm projection to VLO and suggested that the middle and deep layers of VLO receive a specific ipsilateral projection from the dorsal Sm and that the superficial layers receive a projection primarily from the ventral Sm. Injections of WGA-HRP into the lateral hypothalamus, LDT, and MPB confirmed the retrograde labeling findings; the lateral hypothalamus was found to send a projection to the medial Sm, the LDT region to the ventromedial Sm and the MPB to the medial and dorsal Sm. These findings confirm and extend the results of previous studies in cat and rat indicating that Sm has a major and specific reciprocal connection with VLO. This finding, in conjunction with previous studies showing direct spinal and trigeminal inputs and the existence of nociceptive neurons in Sm and VLO, provides further support for a role of Sm in nociception.

Afferent Pathways↗

PubMed1992

Interleukin 8 (IL-8) selectively inhibits immunoglobulin E production induced by IL-4 in human B cells.

The effect of interleukin 8 (IL-8) on IL-4-induced immunoglobulin E (IgE) production was studied. IL-4 induced IgE and IgG4 production by tonsillar mononuclear cells (MNC) without affecting IgM, IgG1, IgA, IgG2, or IgG3 production. IL-8 inhibited IL-4-induced IgE and IgG4 production, whereas it had no effect on IgM, IgG1, IgA, IgG2, and IgG3 production. The inhibitory effect by IL-8 was specific, since it was blocked by anti-IL-8 mAb, but not by control IgG1. Although interferon gamma (IFN-gamma) also inhibited IgE and IgG4 production by MNC stimulated with IL-4, the inhibitory effect of IL-8 was not mediated by IFN-gamma, since the IL-8-induced inhibition could not be blocked by anti-IFN-gamma. Furthermore, anti-IL-8 mAb had no effect on IFN-gamma-induced inhibition. Moreover, addition of IL-5 or IL-6 did not reverse IL-8-induced inhibition of IgE production. In contrast to these observations with MNC, IL-4 failed to induce IgE and IgG4 production by purified B cells. However, combined treatment of purified B cells cells with IL-4 and anti-CD40 antibody resulted in IgE but not IgG4 production. IL-8 inhibited this IgE production without affecting IgM, IgG1, IgG2, IgG3, IgG4, or IgA production, whereas IFN-gamma, IFN-alpha, or prostaglandin E2 (PGE2) failed to do so. These results indicate that IL-8 antagonizes IL-4-induced IgE production by directly affecting B cells through a specific mechanism that is different from IFN-gamma, IFN-alpha, or PGE2.

Antibodies, Monoclonal↗

PubMed1992

Cyclic AMP-dependent phosphorylation and regulation of the cardiac dihydropyridine-sensitive Ca channel.

A polyclonal antibody, CR2, prepared using the C-terminal peptide of the alpha 1 subunit of the rabbit cardiac DHP-sensitive Ca channel, specifically immunoprecipitated the [3H]PN200-110-labeled Ca channel solubilized from cardiac microsomes. The antibody recognized 250 and 200-kDa cardiac microsomal proteins as determined by immunoblotting, and cAMP-dependent protein kinase phosphorylated the 250-kDa, but not the 200-kDa protein in vitro. CHO cells, transfected with the cardiac alpha 1 subunit cDNA carried by an expression vector, synthesized a 250-kDa protein which was recognized by CR2. Adding db-cAMP or forskolin to the transformed CHO cells induced phosphorylation of the 250-kDa protein and stimulated the DHP-sensitive Ba current under patch-clamp conditions. These results suggested that the cardiac DHP-sensitive Ca channel was regulated by cAMP-dependent phosphorylation of the alpha 1 subunit.

Animals↗

PubMed1992

Trigeminal and dorsal column nuclei projections to the anterior pretectal nucleus in the rat.

The projections of the trigeminal (V) sensory nuclei (VSN) and the dorsal column nuclei (DCN) to the anterior pretectal nucleus (APT) of the rat were investigated by the use of anterograde and retrograde transport of wheat-germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). Injections of WGA-HRP into the APT retrogradely labeled neurons in the contralateral VSN and DCN. The labeled neurons in the VSN were most concentrated in the rostral V subnucleus interpolaris (Vi), but were also found in caudal V subnucleus oralis (Vo). No labeled neurons were seen in V subnucleus caudalis. In the DCN, retrogradely labeled neurons were observed in rostral portions of both the cuneate (Cu) and gracile (Gr) nuclei. Injections of WGA-HRP into the rostral Vi or caudal Vo resulted in dense anterograde terminal labeling in the ventral two-thirds of the APT; the labeling was maximal in the ventromedial part of the caudal half of the APT and did not extend into its most rostral portion. Labeling resulting from injections of tracer into Cu or Gr was located primarily in the ventral half of the APT, was maximal in the mid-levels of the nucleus and extended into its rostral portions. These results indicate the existence of prominent somatosensory projections to the APT and are consistent with recent findings suggesting a role for the APT in sensorimotor integration.

Animals↗

PubMed1992

Neurotransmitter release from synaptotagmin-deficient clonal variants of PC12 cells.

Synaptotagmin (p65) is an abundant synaptic vesicle protein of neurons and contains regions similar to the regulatory domain of protein kinase C. These domains are thought to be involved in calcium-dependent interaction with membrane phospholipids during exocytosis. To assess the functional role of synaptotagmin, synaptotagmin-deficient clonal variants of PC12 cells were isolated. All of the variant cells released catecholamine and adenosine triphosphate in response to elevated intracellular concentrations of calcium, which suggests that synaptotagmin is not essential for secretion of catecholamine and adenosine triphosphate from PC12 cells.

Adenosine Triphosphate↗

PubMed1992

Blockade by trifluoperazine of a Ca(2+)-activated K+ channel in rat hippocampal pyramidal neurons.

The effects of trifluoperazine, a phenothiazine derivative, on the large-conductance Ca(2+)-activated K+ channel (BKCa) in dissociated rat hippocampal pyramidal neurons were examined using the inside-out configuration of the patch-clamp technique. The BKCa was activated by 12.6 microM Ca2+ on the internal surface of the membrane patch. The single channel conductance of the BKCa was 244 +/- 17.5 pS (n = 10) in symmetrical solutions of 150 mM K+. Trifluoperazine, applied on the internal surface of the membrane, decreased the open probability of the channel without changing the single channel conductance. The reduction in the open probability was well described by a block of the open state of the channel in a simple sequential model. The apparent dissociation constant (KD) for the reduction was calculated to be 1.4 microM and the Hill coefficient 0.69 at +20 mV. The inhibition was voltage dependent, being more pronounced at depolarized voltages. The voltage dependence enabled us to estimate that the binding site for the agent in the channel lies about half way across the membrane electrical field. It is concluded that trifluoperazine blocks the open state of the BKCa, which is known to provide an outward current for repolarization and afterhyperpolarization of the neuronal action potential. This may result in a decrease in spike intervals during burst firing of neurons.

Action Potentials↗

PubMed1992

Proliferative activity in thyroid tumors.

To clarify the proliferative activity of papillary thyroid carcinoma, the bromodeoxyuridine (BrdU) labeling index (LI) of 61 various thyroid tumors was investigated using an in vitro labeling technique and immunohistochemical staining with anti-BrdU monoclonal antibody. The mean LI (+/- standard deviation) of 31 papillary carcinomas, 12 adenomas, 10 adenomatous goiters, 3 follicular carcinomas, and 2 medullary carcinomas were 1.2% (+/- 1.3%), 0.6% (+/- 0.3%), 0.7% (+/- 0.6%), 1.5% (+/- 2.2%), and 0.7% (+/- 0.6%), respectively. The LI of the papillary carcinomas ranged from 0.1% to 4.6%, and approximately 66% of these showed less than a 1% similarity with almost all benign tumors. However, the LI of the two malignant lymphomas and the one anaplastic carcinoma were more than 13%. When the LI of the papillary carcinomas was compared with their various prognostic factors, there was no correlation with tumor size, nodal status, or morphologic features. However, the patients who were 50 years of age or older tended to have relatively high LI, and the LI of the papillary carcinomas correlated with patient age. According to these results, the biologic characteristics of papillary carcinomas vary with age and high proliferative activity may contribute to the poor prognosis of this tumor in elderly patients.

Adenoma↗

PubMed1992

Molecular abnormalities of a phosphoglycerate kinase variant generated by spontaneous mutation.

A new case of X chromosome-linked phosphoglycerate kinase (PGK) abnormality is described. The male proband was mentally retarded, had behavior disorders, and displayed episodes of hemolytic anemia. The enzyme activity of red blood cells from the patient was about 10% of normal, and that of the cultured fibroblasts was about 50% of normal cells. The variant PGK was characterized by a lower affinity for the substrates, reduced thermostability, and increased anodal electrophoretic mobility. The pH activity profile of the variant enzyme was different from that of normal. The amount of messenger RNA (mRNA) in the variant fibroblasts was comparable to that of normal fibroblasts. The mRNA coding for PGK was subjected to coupled reverse transcription followed by amplification by the polymerase chain reaction. Nucleotide sequence of the variant cDNA showed a point mutation, T/A----C/G transition, in exon 9 of the variant gene. No other mutation was found in all coding regions of the variant. The mutation should cause Cys----Arg substitution at the 315th position from the NH2-terminal Ser of PGK, and it created an additional Ava II (or isoschimatic) cleavage site in the variant gene. Because the variant gene was not detected in the proband's mother and siblings, it must have been generated by spontaneous mutation during oogenesis.

Adult↗

PubMed1992

Human stomach aldehyde dehydrogenase cDNA and genomic cloning, primary structure, and expression in Escherichia coli.

An aldehyde dehydrogenase isozyme, ALDH3, which is strongly expressed in the stomach, may play a role in the oxidation of toxic aldehydes. Using reverse genetic approach, we cloned and characterized the cDNA and the gene for the ALDH3. The full length cDNA is 1624 base pairs (bp) in length and contains an open reading frame encoding 453 amino acid residues. The deduced amino acid sequence shows a high degree of resemblance to that of rat hepatocarcinoma ALDH. The human ALDH3 gene spans about 8 kb in length and consists of 10 exons. The putative TATA and CCAAT boxes are located in the consensus upstream distance from the transcription initiation site. Southern blot analysis of total genomic DNA argues against the proposed two-gene model for the ALDH3 isozymes (Yin, S.-J., Cheng, T.-C., Chang, C.-P., Chen, Y.-J., Chao, Y.-C., Tang, H.-S., Chang, T.-M., and Wu, C.-W. (1988) Biochem. Genet. 26, 343-360). Northern blot hybridization and analysis of PCR amplification products of cellular RNA demonstrated the existence of a high level of ALDH3 mRNA in human stomach and hepatoma cells, but a very low level in the normal liver. Expression of ALDH3 cDNA in Escherichia coli yielded a protein of 55 kDa, which exhibited kinetic properties similar to that found in ALDH3 isozyme purified from human stomach and liver, and was hybridizable with rabbit anti-human-hepatoma ALDH serum.

Aldehyde Dehydrogenase↗

PubMed1992

Deficiency of P62, a putative collagen receptor, in platelets from a patient with defective collagen-induced platelet aggregation.

Recently, we described a platelet antibody against a putative collagen receptor (P62), which was found in a patient with idiopathic thrombocytopenic purpura (ITP) (Blood 69:1712). We now report a deficiency of the P62 receptor in a young man whose platelets showed defective collagen-induced platelet aggregation. He had a mild bleeding tendency and slight thrombocytopenia. The results of coagulation and fibrinolysis studies were normal. The patient's platelets were partially unresponsive to collagen, although aggregation in response to ADP, thrombin, ristocetin, and calcium ionophore (A23187) was almost normal. Adhesion of his platelets to bovine collagen was markedly reduced. Addition of collagen caused no synthesis of thromboxane (TX)B2 in platelet rich plasma (PRP) from this patient. Furthermore, collagen produced no rise of cytosolic free calcium ([Ca2+]i) in fura2-loaded platelets. In contrast, thrombin caused TXB2 formation and an increase of [Ca2+]i in his platelets. These results suggest defective interaction between the platelets and collagen. The IgG from the ITP-patient induced irreversible aggregation in normal PRP, but caused no aggregation of the young man's platelets. Immunoblot studies showed that normal platelets had antigens with a molecular weight of 62 KDa under reducing conditions and of 57 KDa under nonreducing conditions. In contrast, the young man's platelets had no P62 band, although GPIa/IIa and thrombospondin were normally present. These results indicate that impaired collagen-induced aggregation in the patient's platelets was due to a deficiency of P62 and confirm that P62 may play a crucial role as a collagen receptor in platelet activation.

Adenosine Triphosphate↗

PubMed1992

Outward permeability of the blood-retinal barrier.

To characterize quantitatively the active transport mechanism of the blood-retinal barrier (BRB), we estimated the inward (Pin) and outward permeability (Pout) of the BRB in monkey eyes using vitreous fluorophotometry. Pin values for fluorescein (F) and fluorescein glucuronide (FG) were simulated by computer in separate experiments following measurements of intraocular fluorescence at 1 h following the intravenous injection of F or FG. The estimated mean Pin values for F and FG were 4.7 +/- 1.6 and 5.9 +/- 1.7 x 10(-6) cm/min, respectively, in ten eyes of five monkeys. At 1 month thereafter, F was injected into the right vitreous cavity and the same amount of FG was injected into the left vitreous cavity. The intraocular kinetics of fluorescence were measured at 6-24 h postinjection. As estimated by the simulation model, the mean Pout values were 7.7 +/- 2.6 and 1.7 +/- 0.9 x 10(-4) cm/min for F and FG, respectively. The Pout/Pin ratio was 160 +/- 78 for F and 26 +/- 9 for FG. The intraperitoneal injection of probenecid resulted in a significant decrease in the Pout value for F (P less than 0.005) but had no significant effect on that for FG, suggesting that F is excreted from the retina via an active transport mechanism; as characterized by the Pout/Pin ratio, the actual magnitude of the latter is far greater than that previously reported.

Animals↗

PubMed1992

Immunohistochemical studies on oncogene products (EGF-R, c-erbB-2) and growth factors (EGF, TGF-alpha) in human breast cancer: their relationship to oestrogen receptor status, histological grade, mitotic index and nodal status.

In this investigation, 83 human mammary carcinomas were examined for the expression of oestrogen receptor (ER), epidermal growth factor receptor (EGF-R), epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), c-erbB-2, histological grade, mitotic index and nodal status, all of which are reportedly prognostically significant factors (Bloom and Richardson 1957; Baak et al. 1985; Wright et al. 1989). ER expression was biochemically recognized in 43.4% of mammary carcinomas, and EGF-R, EGF, TGF-alpha and c-erbB-2 were histochemically recognized in 25.3, 14.5, 27.7 and 18.0% of mammary carcinomas examined respectively, using conventional sections of buffered formalin-fixed, paraffin-embedded tissue and monoclonal or polyclonal antibodies. There were significant relationships between negative ER and positive EGF-R or TGF-alpha; positive EGF-R and TGF-alpha; positive EGF-R and c-erbB-2; and positive c-erbB-2 and TGF-alpha. The single changes which were the negative ER and the positive c-erbB-2 correlated with histological grade and mitotic index. Co-expression of EGF-R and TGF-alpha correlated with positive nodal status. Therefore, the present investigation indicates that the negative ER, single expression of c-erbB-2 and co-expression of EGF-R and TGF-alpha are important markers which contribute indirectly to prognosis, which reconfirms previous findings on the former two while adding the new finding that immunohistochemical demonstration of expression of EGF-R and TGF-alpha may provide useful information for selecting the appropriate treatment.

Biomarkers, Tumor↗

PubMed1992

Morphological characteristics of tumours formed by Lewis lung carcinoma-derived cloned cell lines with different metastatic potentials: structural differences in their basement membranes formed in vivo.

Tumour basement membrane (BM) is an extracellular matrix produced by tumour cells of epithelial origin. We examined the structure and function of the tumour BM of tumour tissues formed by Lewis lung carcinoma-derived cloned cell lines (P29, LM12-3 and LM60-D6 cells) with low, medium and high metastatic potentials, respectively. Immunohistochemical staining of major BM constituents laminin and type IV collagen demonstrated that all the cell lines produced and deposited these materials extracellularly in vivo. However, the continuity of the tumour BM composed of these materials was much greater in the higher metastatic LM12-3 and LM60-D6 tumours than in those with the low metastatic P29 tumour. Electron microscopic examination revealed that in the higher metastatic tumours, especially the LM60-D6 tumour, the tumour BM had a highly organized structure consisting of lamina densa and lamina rara. Parallel bilayers of BM and their fusion were often observed and tumour cells were in direct contact with the BM. In the vicinity of tumour blood vessels, similar interactions between the tumour BM and the vascular BM were observed, and the tumour cells rested on their own BM, the fused BM or the vascular BM. In contrast, in the low metastatic tumour in which the tumour BM was not clearly defined, this close contact between tumour cells and the vascular BM was not observed. In vitro studies showed that the higher metastatic cells adhered more firmly than the LMP cells to a subendothelial matrix. These results suggest that the adhesiveness of tumour cells to the vascular BM in vivo is correlated with their ability to form an integrated BM in vivo, and that this adhesiveness of the tumour cells may be mediated in part by the tumour BM via BM fusion.

Animals↗

PubMed1992

The effect of a histidine-excess diet on cholesterol synthesis and degradation in rats.

Feeding a diet high in excess histidine (5% L-histidine) resulted in hypercholesterolemia and enlargement of the liver in rats. To clarify the mechanism of the hypercholesterolemia, cholesterol synthesis and degradation were followed. We found that hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity in histidine-excess diet rats was significantly higher than in rats fed a basal diet. Incorporation of [3H] water into cholesterol of liver slices from rats fed the histidine-excess diet was higher than incorporation into liver slices from rats fed the basal diet (expressed per liver per 100 g body weight). In vivo incorporation of [3H] water into hepatic cholesterol was also higher, but the incorporation into cholesterol of the small intestine was lower in histidine-fed rats than in rats fed the basal diet (expressed per liver per 100 g body weight). Hepatic cholesterol 7 alpha-hydroxylase activity was similar in both groups. The data suggest that the hypercholesterolemia caused by histidine-excess diet appears to be due to the stimulation of cholesterol synthesis in the liver.

Animals↗

PubMed1992

Eosinophil cationic protein inhibits immunoglobulin production and proliferation in vitro in human plasma cells.

The effect of eosinophil cationic protein (ECP) on immunoglobulin (Ig) production by and proliferation of human plasma cells was studied. ECP inhibited Ig production by and proliferation of the human plasma cell lines, IM-9 and AF-10, in a dose-dependent fashion. As little as 0.05 ng/ml ECP was found to be inhibitory, and the maximal inhibition was achieved at doses of 0.1-0.5 ng/ml ECP. This inhibition was not due to cytotoxicity, since viability was always greater than 98%. Kinetic experiments demonstrated that inhibition was observable after 24 hr of culture with ECP and that the inhibitory effect of ECP was reversible. The inhibitory effect of ECP could be blocked by anti-ECP serum, but not by control serum. Of the various cytokines tested, including interleukin (IL)-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, interferon (IFN)-alpha, IFN-gamma, granulocyte-macrophage colony-stimulating factor (GM-CSF) and erythropoietin (Epo), IL-6 reversed the inhibition, while other cytokines failed to do so. ECP also inhibited Ig (IgG1, IgG2, IgG3, IgG4, IgM, and IgA) production by and proliferation of PCA-1+ plasma cells generated in vitro with a similar dose-response pattern. This inhibition also was blocked by anti-ECP serum but not by control serum, and was restored by IL-6. These results suggest that ECP may interact with IL-6 in controlling plasma cell responses.

Blood Proteins↗