Effect of salt concentration on the pKa of acidic residues in lysozyme

We determined the pKa values of acidic residues in hen lysozyme by comparing the pH dependency of stability between wild type and mutant lysozymes in which a negative charge is eliminated. In the comparison of the stability between wild type and a mutant lysozyme, the difference in pH titration curve between them could be expressed as a two-state process involving protonation of a single acidic residue. The results strongly indicated that the Aune and Tanford theory of protein denaturation [Aune, K.C. and Tanford, C. (1969) Biochemistry 8, 4579-4585] is applicable to protein stability in solution. On the other hand, the pKa values of acidic residues in the presence of low (5 mM) or high (400 mM) salt concentration were determined by means of two-dimensional NMR. We found that the pKa values obtained from the pH dependency of stability were close to those from the NMR experiment under the high salt condition. Moreover, by comparing pKa values at high salt and low salt concentrations, we could evaluate the dependency of two electrostatic interactions (salt bridge and charge-helix dipole interaction) on salt concentration.

[Study of anti-tumor effects of hyperthermia combined with hydralazine on experimental tumor]

We analyzed tumor growth delay in experimental tumors after hyperthermia alone, hydralazine (HDZ) injection alone and the combination of these modalities. We also analyzed the energy parameter (ATP/Pi ratio) obtained by 31P-MRS (magnetic resonance spectroscopy). The purpose of this study was to evaluate the usefulness of 31P-MRS as an index of anti-tumor effect. FM3A tumor cells were transplanted subcutaneously in the hind legs of C3H/He mice. We dipped the tumors into a heated circulating water bath. 31P-MRS was performed with a CSI spectrometer. The anti-tumor effect obtained with HDZ alone was insignificant, but combined treatment with hyperthermia and HDZ had a significant synergistic effect. The ATP/Pi ratios for all groups treated separately with HDZ or hyperthermia were not different from the control, but the ATP/Pi ratio decreased after combined use of these agents. There was a significant correlation between the decrease in ATP/Pi ratio and tumor growth delay. We observed a direct relation between the delay in tumor growth and the decline in ATP/Pi ratio after combined treatment with HDZ and hyperthermia. The ATP/Pi ratio 24 hr after treatment may be useful in predicting the efficacy of the combined use of HDZ and hyperthermia.

The functional hepatic volume assessed by 99mTc-GSA hepatic scintigraphy

The accuracy of measurement of the functional hepatic volume by single photon emission computed tomography (SPECT) with 99mTc-galactosyl serum albumin (99mTc-GAS) was evaluated. 99mTc-GSA planar scintigraphic images were obtained dynamically and the hepatic SPECT imaging was then performed in 25 patients with hepatobiliary tumors. The patients were divided into 4 groups with normal hepatic function, and mild, moderate and severe hepatic dysfunction. The functional hepatic volume determined by SPECT was compared with the morphological hepatic volume determined by compute tomography. The ratio of the hepatic volumes obtained by the two methods was calculated. The mean hepatic volume ratio was 96.6 +/- 2.3% in the normal hepatic function group and 95.9 +/- 2.2% in the mild dysfunction group (n.s.). In both the moderate and severe hepatic dysfunction groups, the hepatic volume ratio was smaller than that in the normal group (87.9 +/- 5.2%, p < 0.0001, and 71.9 +/- 7.6%, p < 0.0001, respectively). There was a linear correlation between the hepatic volume ration and various indices of reserve hepatic function, such as LHL15 (r = 0.83, p < 0.0001), HH15(r = 0.74, p < 0.0001), and ICG15 (r = 0.75, p < 0.0005). These results indicate that the hepatic volume ratio is proportional to the severity of hepatic dysfunction, and suggest that the functional hepatic volume measured with 99mTc-GSA faithfully reflects the functioning hepatocyte mass. 99mTc-GSA scintigraphy and hepatic SPECT therefore provide information regarding global and regional reserve hepatic function.

High affinity IgE receptor-mediated prostaglandin E2 production by monocytes in atopic dermatitis

High affinity IgE receptor (Fc epsilon R I) expression on monocytes and its upregulation on monocytes from patients with atopic dermatitis (AD) have been recently reported. In this study, we investigated whether prostaglandin E2 (PGE2) release from AD monocytes was Fc epsilon R I-dependent or not. The monocytes were stimulated with anti-Fc epsilon R I monoclonal antibody (mAb) and anti-Fc epsilon R II mAb. Cross-linking of Fc epsilon R I, but not that of Fc epsilon R II induced PGE2 release from monocytes. In order to confirm that the PGE2 release is IgE-dependent, stimulation with IgE+anti-IgE, IgG+anti-IgG and immune complexes made by incubation with AD patients' serum and recombinant Der fII (rDer fII-IC) were carried out in the culture. Significant PGE2 release by all the stimulants was observed, as compared with spontaneous release. PGE2 release by immune complex made by incubation with IgE-absorbed AD serum and rDer fII was much lower than that by rDer fII-IC. In monocytes from nonatopic donors, significant PGE2 release was observed when stimulated with IgE+anti-IgE, IgG+anti-IgG, rDer fII-IC, but not with anti-FC epsilon R I mAb and anti-Fc epsilon R II mAb. However, the release were significantly lower than respective PGE2 releases from AD monocytes. Taken together, cross-linking of Fc epsilon R I and IgE induced a PGE2 release from monocytes. This is a first report demonstrating an Fc epsilon R I-dependent mediator release from monocytes of AD patients.

Stereospecific taurine conjugation of the trans-OH metabolite (active metabolite) of CS-670, a new 2-arylpropionic acid nonsteroidal anti-inflammatory drug, in dogs

CS-670, (+/-)-2-[4-(2-oxocyclohexylidenemethyl)phenyl]propionic acid, is a novel derivative of 2-arylpropionic acid non-steroidal anti-inflammatory drugs (profen NSAIDs). The major urinary metabolite of this drug from dogs was isolated and its chemical structure was determined by MS and NMR spectroscopy. The metabolite was identified as a taurine conjugate of the trans-OH form (trans-OH-taurine) which was first generated by stereoselective reduction of the double bond and the carbonyl function of the CS-670 molecule. The taurine conjugate was excreted in urine as the main metabolite, regardless of the optical configuration of CS-670 administered [2R)-enantiomer: 47.2% of the dose, (2S)-enantiomer: 70.9% of the dose]. The trans-OH-taurine was hydrolyzed by refluxing it in 6 N HCl without racemization. The released trans-OH was derivatized to diastereoamides with (+)-(R)-1-(1-naphthyl)ethylamine to examine the stereochemical properties of the 2-arylpropionic acid side chain. It was found that the configuration of the 2-carbon of the trans-OH-taurine was almost entirely (S). As the CoA thioesters are obligate intermediates for amino acid conjugation, the results suggest that the (2S)-enantiomer of the trans-OH metabolite serves as a substrate for canine acyl CoA ligase (EC 6.2.1.3) as well as the (2R)-enantiomer, but only the CoA thioester with a (2S)-configuration is a substrate for taurine N-acyl transferase. It is interesting to note that these results are not consistent with the chiral inversion mechanism by which the (2R)-enantiomers of profen NSAIDs are stereospecifically converted to CoA thioester intermediates.

Lung metastasis from parathyroid carcinoma causing recurrent renal hyperparathyroidism in a hemodialysis patient: report of a case

We report herein the case of a 46-year-old woman on hemodialysis (HD) who developed recurrent renal hyperparathyroidism induced by lung metastasis from parathyroid carcinoma. The patient had been commenced on HD for chronic renal failure about 20 years earlier and had undergone a parathyroidectomy for advanced renal hyperparathyroidism 8 years later. After the initial operation, further explorations of the neck were performed due to recurrence, despite which the hyperparathyroidism persisted and she was finally referred to our department. The appearance of multiple coinlike lesions on a chest X-ray and computed tomography led to the diagnosis of recurrent hyperparathyroidism induced by lung metastasis from parathyroid carcinoma. A pulmonary wedge resection was performed and the metastatic parathyroid nodules were removed. Of the several hypotheses about the etiology of parathyroid carcinoma in HD patients, it is most likely that the parathyroid hyperplasia induced by chronic renal failure develops into carcinoma. Even in renal hyperparathyroidism, we should bear in mind the possibility that metastatic parathyroid carcinoma is a possible source of excess parathyroid hormone secretion at recurrence.

Spontaneous production of various cytokines except IL-4 from CD4+ T cells in the affected organs of sarcoidosis patients

We investigated surface antigens and spontaneous cytokine production of T cells from bronchoalveolar lavage fluid (BALF) and aqueous humor (AH) from pulmonary sarcoidosis patients for a better understanding of the role of T cells in granuloma formation. The levels of CD3, CD11b, and CD28 antigen expression on freshly isolated T cells in the BALF of patients were significantly lower than those in peripheral blood lymphocytes (PBL) of either sarcoidosis patients or healthy donors (HD). In contrast, the levels of CD80 (B7/B7-1) and CD86 (B70/B7-2) antigen expression were significantly higher on these T cells and alveolar macrophages in the BALF of patients. Fifty-three T cell clones (TCC) established from the BALF and AH of the three sarcoidosis patients displayed primarily either CD4+ CD11b+ CD28+ or CD4+ CD11b- CD28- phenotypes. Most (61-90%) of these TCC spontaneously produced greater amounts of IL-1 alpha, IL-10, tumour necrosis factor (TNF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) than did TCC from the PBL from sarcoidosis patients or HD (P < 0.05). Interferon-gamma (IFN-gamma), IL-6, and IL-2, but not IL-4, were also produced by 40-48% of these TCC. These results suggest that CD4+ T cells of the affected organs of sarcoidosis patients are activated and involved in the immunopathogenesis of sarcoidosis through production of various cytokines.

Senescence-induced expression of a homologue of delta 9 desaturase in rose petals

cDNAs for senescence-inducible genes were isolated by differential hybridization from a cDNA library derived from mRNAs from the petals of rose flowers. The amino acid sequence deduced from these cDNAs exhibited significant homology to those of delta 9 acyl-lipid desaturases of cyanobacteria and of delta 9 acyl-CoA desaturases of a yeast and mammals. There was no amino-terminal sequence indicative of a leader peptide for targeting to the chloroplasts or to mitochondria. Northern blot analysis indicated that the transcripts of the cDNAs were expressed specifically in petals at late developmental stages and during senescence. It is proposed that a delta 9 desaturase in the senescing petals play an important role in the degradation of saturated fatty acids of membrane lipids.

Partial purification and characterization of histidine acetyltransferase in brain of Nile tilapia (Oreochromis niloticus)

High activity of histidine acetyltransferase (HISAT) was found in the brain and the lens of Nile tilapia Oreochromis niloticus. HISAT was semi-purified 4166-fold from the brain of Nile tilapia. The affinity chromatography using a Blue Sepharose 6 FF column was very effective for purification of this enzyme. The enzyme had a broad pH optimum from pH 7.0 to pH 9.5, and did not require any divalent metal ion. The semi-purified HISAT showed a strict substrate specificity for L-histidine (and its methyl derivatives) and acetylcoenzyme A (CoASAc). The reaction velocity fits normal Michaelis-Menten kinetics with respect to both L-histidine (Km, 0.45 mM) and CoASAc (Km, 0.027 mM). Gel filtration on Superdex 200 HR indicated the molecular weight of 39,000. It was presumed that the 38.5 kDa protein, which was intensely visualized in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was a single subunit derived from HISAT.

Establishment of an enzyme-linked immunosorbent assay (ELISA) for measuring cellular MAGE-4 protein on human cancers

The MAGE genes encoding tumor-rejection antigens are expressed on various human cancers. An enzyme-linked immunosorbent assay (ELISA) was established for measuring cellular MAGE-4 protein (MAGE-4a and/or -4b) expressed on human tumor cells using a monoclonal antibody (mAb) and polyclonal Ab to recombinant MAGE-4b protein. Both the R5 mAb (IgG1) and the polyclonal Ab recognized a 45 kDa protein in extracts of MAGE-4 mRNA positive cancers, and showed no apparent cross-reactivity to the other MAGE gene products (MAGE-1, -2, -3, -6, and -12) by the immunoblot analyses. The R5 mAb and the polyclonal Ab primarily recognized one (the position 119-133) and two oligopeptides (the positions 119-133 and 259-273), respectively, among a series of 31 different MAGE-4b oligopeptides. The amino acid sequences of these two peptides were identical to those of MAGE-4a and -4b, but differed from those of all the other MAGE proteins (MAGE-1, -2, -3, -6, and -12). Substitution of glycine for amino acid in position 123 (arginine, R), 124 (lysine, K), 126 (R) or 128 (K) in a MAGE-4b oligopeptide of the position 119-132 severely decreased the reactivity of the R5 mAb to the oligopeptide. This ELISA also showed no apparent cross-reactivity with the other MAGE gene products (MAGE-1, -2, -3, -6, and -12). The minimum detectable level of MAGE-4 protein was determined to be 10 pg/well (100 pg/ml). The results suggest that this ELISA is a reliable and quantitative method to measure cellular MAGE-4 protein that is a potential target molecule for specific immunotherapy of human cancers.

Impaired release of cholecystokinin (CCK) from synaptosomes in old rats

Cholecystokinin (CCK) is an abundant neurotransmitter peptide in the brain. CCK release from synaptosomes obtained from the cerebral cortex, the level of CCK mRNA and the tissue concentration of CCK were examined in young and old rats. CCK release stimulated by KCl was attenuated in old rats but that stimulated by calcium ionophore was comparable in animals at both ages. The CCK mRNA level in the cerebral cortex was decreased significantly in old rats despite the significant increase in CCK content. These results suggested that aging impaired CCK release, resulting in tissue accumulation and a decrease in the synthesis of CCK (the level of CCK mRNA).

Osteoblasts are regulated by the cellular adhesion through ICAM-1 and VCAM-1

The two major processes of bone metabolism--bone formation and resorption--are regulated by cellular interactions. Osteoblasts and osteoclasts play a significant role in bone metabolism, which is known to be regulated by local soluble factors and systemic hormones. Although bone is a heterogeneous tissue comprised of osteogenic and hematopoietic cells, cellular adhesion of osteoblasts and its regulation remains to be understood. We first demonstrate that cellular adhesion by which osteoblasts communicate with opposing cells in bone milieu is involved in the osteoblast activation: (a) purified human osteoblasts obtained from osteoarthritis patients expressed particular adhesion molecules, ICAM-1, VCAM-1, and LFA-3; (b) toe osteoblasts adhered to T cells which were used as representative adhesive partners, since T cells possess all the receptors to these adhesion molecules; (c) mRNA transcription and secretion of IL-1beta and IL-6 were induced in the osteoblasts by the cellular adhesion to T cells and they were reduced by interrupting the adhesion; (d) cross-linking of ICAM-1 and VCAM-1 on the osteoblasts induced IL-6 secretion from the osteoblasts. These results indicate that osteoblasts adhere to opposing cells through particular adhesion molecules on their surface and that the adhesion molecules on the osteoblasts not only function as glue with opposing partners but transduce activation signals that facilitate the production of bone-resorbing cytokines. We propose that cellular adhesion of osteoblasts as well as soluble factors is significant for the regulation of bone metabolism.

Direct presentation of nonpeptide prenyl pyrophosphate antigens to human gamma delta T cells

Human V gamma 2V delta 2+ T cells recognize mycobacterial nonpeptide antigens, such as isopentenyl pyrophosphate, and their synthetic analogs, such as monoethyl phosphate, through a TCR-dependent process. Here, we examine the presentation of these antigens. V gamma 2V delta 2+ T cells recognized secreted prenyl pyrophosphate antigens in the absence of other accessory cells but, under such conditions, required T cell-T cell contact. Recognition required neither the expression of classical MHC class I, MHC class II, or CD1a, CD1b, and CD1c molecules, nor MHC class I or class II peptide loading pathways. Fixed accessory cells also presented the prenyl pyrophosphate antigens to gamma delta T cells. Thus, in contrast with the presentation of conventional peptide antigens, protein antigens, and superantigens to alpha beta T cells, prenyl pyrophosphate antigens are presented to gamma delta T cells through a novel extracellular pathway that does not require antigen uptake, antigen processing, or MHC class I or class II expression. This pathway allows for the rapid recognition of bacteria by gamma delta T cells and suggests that gamma delta T cells play a role in the early response to bacterial infection.

Sensitive chemiluminescence enzyme immunoassay for vascular endothelial growth factor/vascular permeability factor in human serum

A sandwich chemiluminescence enzyme immunoassay for measuring the level of VEGF/VPF in serum was constructed. The detectability of the assay is very low (1.0 pg/ml) and the measurable range of the assay was very wide (1-1000 pg/ml). The assay showed that the average level of VEGF/VPF in human sera from healthy blood donors was approximately 19 pg/ml.

[A prospective randomized clinical trial comparing intra-arterial chemotherapy alone and when combined with hyperthermia for metastatic liver cancer]

To evaluate the efficacy of intra-arterial chemotherapy combined with hyperthermia for metastatic liver cancer, our cooperative study group carried out a randomized clinical trial comparing intra-arterial chemotherapy alone and intra-arterial chemotherapy combined with hyperthermia. Patients were treated with combined chemotherapy of epirubicin (EPIR), mitomycin C (MMC), 5-fluorouracil (5-FU), by hepatic infusion using a subcutaneously implanted reservoir. Hyperthermia (8MHz radiofrequency) was usually performed for 40-60 min every week, and intra-arterial chemotherapy was performed immediately before hyperthermia. Twenty-six patients were registered by telephone contact and allocated at random to groups treated with either intra-arterial chemotherapy alone (14 patients) or combination therapy (12 patients). The response rate was 7% in the chemotherapy alone group (1 PR among 14 evaluable patients), and 40% in the combination therapy group (4 PR among 10 evaluable patients). Our results suggest that intra-arterial chemotherapy combined with hyperthermia is a useful modality for the treatment of metastatic liver cancer.

[Adenosine deaminase isoenzymes in patients with Graves' disease]

CD26, the T cell activation antigen, is identical to the ADA binding protein and is considered to interact with ADA to activate the T cells on the surface. Therefore, we examined the activity of serum ADA isoenzymes in patients with Graves' disease in whom CD26 presented T cells were increased. The activities of total ADA and ADA2 were significantly higher in Graves' disease than normals. We also observed that the levels of soluble interleukin-2 receptor (sIL-2R) and neopterin, markers of T cell activation, were significantly higher in Graves' disease. The correlation coefficients among ADA2, neopterin, and sIL-2R were significantly high (p < 0.001). Among these parameters, only sIL-2R was correlated with the thyroid hormones. ADA2 activity was considered to reflect the activated state of T cells and to be, independent of the thyroid hormone levels.

Detection of an increase in ascorbate radical in an irradiated experimental tumour system using ESR

We measured Asc.- (ascorbate radical) produced by the reaction of AscH- (ascorbic acid) with HO. or O2.- after irradiation in mouse. It is possible to measure Asc.- easily using ESR and a dialysis method in which Asc.- was collected at room temperature in the interstitial fluid through the dialysis membrane. After irradiation, Asc.- increased in both normal muscle and tumour tissues (SCC-VII) in proportion to the radiation dose. Asc.- increased after treatment with the agents H2O2 and FeCl2, while it decreased after treatment with SOD and catalase. These results suggest that the amount of HO. and O2.- produced is reflected in the Asc.- production. Also, the increase in Asc.- production when WR-2721 was administered prior to irradiation was less than for experiments in which irradiation only was performed. This method is useful for the following reasons. First, no special treatment, such as freezing of the sample, and no administration of noxious agents are necessary to measure Asc.-. Second, irradiation using a dose of only a few Gy shows an increase in production of Asc.-. Third, this method does not require removal of organs. Using this method, Asc.- can serve as an indicator of the amount of HO. and O2.- produced by irradiation in vivo.

[Effects of ethyl all-cis-5,8,11,14,17-icosapentaenoate on low density lipoprotein in rabbits]

The hypolipidemic effects of ethyl all-cis-5,8,11,14,17-icosapentaenoate (EPA-E) on cholesterol diet-fed rabbits were studied. EPA-E (300 mg/kg, p.o. x 4 weeks) decreased total cholesterols in the lipoprotein fractions of very low-density lipoprotein and intermediate lipoprotein+low-density lipoprotein (LDL), but not in high-density lipoprotein. Furthermore, the properties of LDL were investigated in rabbits given EPA-E (300 mg/kg, p.o. x 2 weeks). EPA-E had no influence on the lipid composition in LDL, and the cholesterol accumulation into macrophages was not increased by the incubation with EPA-E-treated LDL. However, the omega 3 polyunsaturated fatty acids contents of LDL were increased by the administration of EPA-E. EPA-E-treated LDL was also studied on the binding to the hepatic membranes. The binding of EPA-E-treated LDL to the hepatic membranes was higher than that of ordinary LDL. These results suggest that EPA-E causes a modification of LDL, such that EPA-E has an enhancing effect on the hepatic uptake of LDL. These effects may contribute to the hypolipidemic action of EPA-E.

[Genetic analysis by fluorescence in situ hybridization of lung cancer cells obtained by bronchial brushing]

Fluorescence in situ hybridization was done with specimens obtained by bronchial brushing from 25 patients with abnormal lung shadows. A satellite DNA probe, specific for chromosome 11, was used to detect numerical chromosome aberrations in tumor cell nuclei. Normal diploid human lymphocyte nuclei, which served as control, had two signal spots in 99.6% of the nuclei in response to the chromosome 11 probe. The most frequent signal spots in class V cells (Case 1-7) ranged from 3 to 5, followed by 6 to 8, regardless of histopathological findings of lung cancer. In class I cells (cases 8-11) the signal appearance was similar to that in class V cells. The disease in patients from whom class I cells were obtained was found to be malignant by other diagnostic procedures performed afterward. The abnormalities in cases 13-25 were diagnosed as non-malignant by brush cytology, and clinical course showed a little more than 3 spots. These data indicate that fluorescence in situ hybridization with specimens obtained by bronchial brushing can be useful for detecting numerical chromosome abnormalities and can aid in the rapid diagnosis of lung cancer.

[Microorganisms cultured from sputum and blood in association with episodes of fever during anti-cancer therapy in patients with lung cancer]

We examined the clinical features and significance of pathogenic microbes isolated from sputum and blood of patients with lung cancer during anti-cancer therapy. Pathogenic bacteria were more likely to be isolated from patients with episodes of fever than from afebrile patients. The major species of bacteria isolated from sputum were Staphylococcus aureus, including methicillin-resistant strains, and Gram-negative bacilli, which are known to be frequently involved in hospital-acquired infections. The presence of an indwelling central venous catheter for intravenous hyperalimentation was an important risk factor for the development of a febrile episode, which indicates that bacteremia was a major cause of fever. In one quarter of the blood cultures from the patients with persistent fever, various species of pathogenic microbes were recovered, one-third of which were fungi. Bacteriological examinations done before and after the introduction of granulocyte-colony stimulating factor (G-CSF) revealed that strains of Klebsiella spp. decreased and those of methicillin-resistant S. aureus increased. There was no firm evidence that G-CSF decreased the incidence of episodes of fever. However, remains G-CSF may a allow the dose intensity of anti-cancer agents to be increased, which would lead to severe leukocytopenia. However, more detailed investigation is needed to clarify the role of G-CSF against bacterial infection during anti-cancer therapy.

Pathogenic Nocardia isolated from clinical specimens including those of AIDS patients in Thailand

Forty strains of nocardioform microorganisms were isolated as clinical specimens including several from AIDS patients in Thailand. Among them, 37 strains were found to belong to the genus Nocardia. Our identification studies revealed that most of the strains (25 strains) belong to the N. asteroides group, i.e., N. asteroides sensu stricto and N. farcinica. Three strains were identified as N. otitidiscaviarum and two strains N. brasiliensis. In addition, 7 strains of rare pathogenic N. transvalensis were also isolated.

Effect of specific binding of high density lipoprotein to eel hepatocytes on their secretion of lipoprotein

Specific binding of eel serum high-density lipoprotein (HDL) to eel hepatocytes was demonstrated by using a synthesized fluorescent lipophilic dye. HDL binding was inhibited by the addition of unlabeled HDL. The binding of HDL to the hepatocytes was saturated at concentrations over 100 micrograms HDL protein/ml and Kd value was 20 micrograms HDL protein/ml. A fluorescent photomicrograph of the cultured eel hepatocytes which were incubated with the dye showed the bright, circumferential plasma membranes stained with the dye. 125I-HDL was incorporated into the acid insoluble- and soluble-fractions of the cultured hepatocytes during incubation at 28 degrees C for 1 h. There are three remarkable characteristics of the effect of HDL on the cultured hepatocytes. One is that the addition of HDL to the hepatocytes induced the efflux of cholesterol, triacylglycerol, and phospholipid from the hepatocytes. The second characteristic is that the efflux of the intracellular lipids was carried out with very-low-density-like or chylomicron-like lipoprotein secreted by the hepatocytes. The third characteristic is that HDL specifically stimulated the synthesis of the lipoprotein and had no effect on the synthesis of intracellular proteins and the secreted proteins except for the lipoprotein.

N-acetylgalactosamine (GalNAc) transfer to the common carbohydrate-protein linkage region of sulfated glycosaminoglycans. Identification of UDP-GalNAc:chondro-oligosaccharide alpha-N-acetylgalactosaminyltransferase in fetal bovine serum

During the course of a study of elucidate the role of modification of the common polysaccharide-protein linkage structure, GlcA beta 1-3Gal beta 1-3Gal beta 1-4Xyl beta 1-O-Ser, in biosynthetic sorting mechanisms of the different sulfated glycosaminoglycan chains, a novel N-acetylgalactosamine (GalNAc) transferase was discovered in fetal bovine serum. The enzyme catalyzed the transfer of [3H]GalNAc from UDP-[3H]GalNAc to linkage tetrasaccharide and hexasaccharide serines synthesized chemically and to various regular oligosaccharides containing terminal D-glucuronic acid (GlcA), which were prepared from chondroitin and chondroitin sulfate using testicular hyaluronidase digestion. The labeled products obtained with the linkage tetra- and hexasaccharide serines and with the tetrasaccharide (GlcA beta 1-3GalNAc)2 were resistant to digestion with chondroitinase AC-II and beta-N-acetylhexosaminidase but sensitive to alpha-N-acetylgalactosaminidase digestion, indicating that the enzyme is an alpha-N-acetylgalactosaminyltransferase. This finding is in contrast to that of Rohrmann et al. (Rohrmann, K., Niemann, R., and Buddecke, E. (1985) Eur. J. Biochem., 148, 463-469), who reported that a corresponding product was susceptible to digestion with beta-N-acetylhexosaminidase. The presence of a sulfate group at C4 of the penultimate GalNAc or Gal units markedly inhibited the transfer of GalNAc to the terminal GlcA, while a sulfate group at C6 of the GalNAc had little effect on the transfer. Moreover, a slight but significant transfer of [3H]GalNAc was observed to an oligosaccharide containing terminal 2-O-sulfated GlcA as acceptor, whereas no incorporation was detected into oligosaccharides containing terminal unsaturated or 3-O-sulfated GlcA units. These results suggest that this novel serum enzyme is a UDP-GalNAc:chondro-oligosaccharide alpha 1-3- or 1-4-N-acetylgalactosaminyltransferase. The possibility of involvement of this enzyme in glycosaminoglycan biosynthesis is discussed.

Calcium-dependent homotypic adhesion through leukocyte function-associated antigen-1/intracellular adhesion molecule-1 induces interleukin-1 and parathyroid hormone-related protein production on adult T-cell leukemia cells in vitro

Adult T-cell leukemia (ATL) is a human T-cell leukemia virus type I (HTLV-I)-infected lymphoproliferative disorder that shows a characteristic nodular infiltration into various tissues, hypercalcemia, and subsequent rapid increase of peripheral ATL cell number. ATL cells and HTLV-I-infected T-cell lines also make cluster formation rapidly after the non-stimulative culture. However, the mechanism of the acute proliferation of ATL cells remains to be understood. We report the following novel features of homotypic adhesion via leukocyte function-associated antigen-1 (LFA-1)/intracellular adhesion molecule-1 (ICAM-1) pathway that suggest a role for it in cytokine production and rapid proliferation of ATL cells: (1) ATL cells show clustering in a calcium dependent manner, even at the higher concentration; (2) ATL cells consistently and highly express ICAM-1 and an active form of LFA-1, whereas integrin expression, except for LFA-1, is rather lower compared with that of normal CD4+ T cells; (3) ATL cells make conjugate formation within 6 minutes and clustering within 48 hours, both of which are inhibited by the addition of monoclonal antibodies (MoAbs) against LFA-1 and ICAM-1; (4) spontaneous mRNA transcription and protein secretion of both interleukin-1 and parathyroid hormone-related protein are observed consistently in ATL cells, and these productions are inhibited by anti-LFA-1 and anti-ICAM-1 MoAbs but are markedly increased by cross-linking of LFA-1 and ICAM-1 by the immobilized specific MoAbs; and (5) proliferative responses of ATL cells are also inhibited by these MoAbs. We propose that ATL cells proliferate in sequential events: the homotypic and calcium-dependent adhesion through LFA-1/ICAM-1, the signal transduction through these adhesion molecules, the production of cytokines, and the proliferation.