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H Otani

Publications and source records attributed to H Otani.

At least 127 records · Page 7Linked to original sources
PubMed1996

Elevated basic fibroblast growth factor in pericardial fluid of patients with unstable angina.

BACKGROUND: Collateral growth is induced by chemical signals from the ischemic myocardium. We hypothesized that angiogenic growth factors are produced by cardiac tissue; they are diffusible, more concentrated in pericardial fluids, and are increased by myocardial ischemia. METHODS AND RESULTS: With the use of an enzyme-linked immunosorbent assay, we measured the concentrations of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in pericardial fluids of 12 patients with unstable angina (group 1) and of 8 patients with nonischemic heart diseases (group 2). The levels of protein in pericardial fluids were quite comparable between the two groups (34 +/- 2 versus 32 +/- 4 mg/mL). The concentration of bFGF in pericardial fluids in group 1 was 2036 +/- 357 pg/mL, significantly (P < .001) higher than the 289 +/- 72 pg/mL in group 2. The amount of bFGF per milligram of protein was also significantly (P < .05) higher in group 1 than in group 2 (67 +/- 15 versus 12 +/- 4 pg/mg). The concentration of VEGF in pericandial fluids tended to be higher in group 1, but the difference was statistically insignificant (39 +/- 7 versus 22 +/- 6 pg/mL). The amount of VEGF per milligram of protein was 1.2 +/- 0.3 pg/mg in group 1, similar to the 0.8 +/- 0.4 pg/mg in group 2. CONCLUSIONS: This finding provides new evidence that bFGF plays an important role in mediating collateral growth in humans.

Aged↗
PubMed1996

RAP, a specialized chaperone, prevents ligand-induced ER retention and degradation of LDL receptor-related endocytic receptors.

The multifunctional low density lipoprotein (LDL) receptor-related protein (LRP) forms a complex with a receptor-associated protein (RAP) within the secretory pathway. RAP inhibits ligand binding to LRP and is required for normal functional expression of LRP in vivo, suggesting a physiological function as a specialized chaperone. We have used RAP-deficient mice, generated by gene targeting, to investigate the role of RAP in the biosynthesis and biological activity of LRP and other members of the LDL receptor gene family in various organs and in embryonic fibroblasts. Our results demonstrate that RAP is required for the proper folding and export of the receptors from the endoplasmic reticulum (ER) by preventing the premature binding of co-expressed ligands. Overexpression of apolipoprotein E (apoE), a high affinity ligand for LRP, results in dramatically reduced cellular LRP expression, an effect that is prevented by co-expression of RAP. RAP thus defines a novel class of molecular chaperones that selectively protect endocytic receptors by binding to newly synthesized receptor polypeptides, thereby preventing ligand-induced aggregation and subsequent degradation in the ER.

Animals↗
PubMed1996

Intracellular signaling pathway of substance P-induced superoxide production in human neutrophils.

We examined the intracellular mechanisms of substance P-induced superoxide anion (O2-) production in human neutrophils. Addition of substance P (30 microM) caused O2- production and biphasic increases in intracellular Ca2+ concentrations ([Ca2+]i) (early transient and subsequent sustained components) associated with the formation of inositol 1,4,5-trisphosphate (IP3). O2- and [Ca2+]i were assayed by using ferricytochrome C and fura 2-AM, respectively. These responses were abolished by tachykinin NK1 receptor antagonists, [D- Pro9[spiro-gamma-lactam],Leu10,Trp11]physalaemin-(1-11) (GR82334) or [D-Arg1,D-Trp7,9,Leu11]substance P (spantide), and an intracellular Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM). Inhibition of IP3 formation by GTP-binding protein (G-protein) inactivators such as guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) and islet-activating protein (IAP), or a phospholipase C inhibitor, 1-[6-[[17 beta-3-methoxyestra-1,3,5(10)- trien-17-yl]amino]hexyl]1 H-pyrrole-2,5-dione (U-73122), blocked the substance P-induced O2- production and biphasic increases in [Ca2+]i. An IP3 receptor antagonist, heparin, reduced both the substance P-induced O2- production and the transient increase in [Ca2+]i without any significant effects on the sustained increase in [Ca2+]i. Protein kinase C inhibitors, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7) and calphostin C, only slightly suppressed O2- production, and abolished the sustained increase in [Ca2+]i without any significant effects on the transient increase in [Ca2+]i. A Ca2+ entry blocker, nicardipine, completely inhibited the sustained increase in [Ca2+]i without affecting O2- production and the transient increase in [Ca2+]i. These results suggest that the tachykinin NK1 receptor/G-protein-linked IP3 formation with the resulting IP3-induced transient increase in [Ca2+]i is the main signal transduction pathway for substance P-stimulated O2- production in neutrophils.

Calcium↗
PubMed1996

Mechanisms of oxyradical production in substance P stimulated rheumatoid synovial cells.

We examined the intracellular mechanisms of substance P induced oxyradical production in rheumatoid synovial cells by the luminol-dependent chemiluminescence method. After stimulation with substance P (30 microM), single synovial A (macrophage-like) or B (fibroblast-like) cells released oxyradicals such as superoxide anions (O2-) and/or hypochlorous anions (OCl-) under a microscope equipped with an ultrasensitive photonic image intensifier. The substance P induced oxyradical production was blocked by a tachykinin NK1 (NK1) receptor antagonist, GR82334, GTP-binding protein (G-protein) inactivators, GDP beta S and islet-activating protein (IAP), and a phospholipase C (PLC) inhibitor, U-73122. Substance P (30 microM) also induced a transient increase in the intracellular Ca2+ concentration ([Ca2+]i) in both synovial A and B cells as measured by a Ca2+ indicator, fura 2, BAPTA-AM and an inositol-1,4-5-triphosphate (IP3) receptor antagonist, heparin, inhibited the substance P induced increase in [Ca2+]i, but they had no effects on oxyradical production. In contrast to the effects of BAPTA-AM and heparin, protein kinase C (PKC) inhibitors, H-7 and calphostin C, completely inhibited substance P induced oxyradical production without any significant effects on [Ca2+]i increase. These findings suggest that the NK1 receptor/PLC-linked diacylglycerol (DAG) formation with the resulting activation of PKC is the main signal transduction pathway for substance P stimulated oxyradical production in synovial cells.

Arthritis, Rheumatoid↗
PubMed1996

Immunohistochemical study of 28-kD heat shock protein in the lens of young human embryos.

The localization of 28-kD heat shock protein (HSP28) in the lenses of human embryos (Carnegie stages 13-21) was studied immunohistochemically using antibodies for HSP28. At stage 13, HSP28 was observed in the lens placode. At stage 15, when the lens vesicle is formed by the invagination of the lens placode, HSP28 was observed in the posterior portion of the lens vesicle. From stages 16 to 18, when the posterior portion of the lens epithelium elongates toward the anterior lens epithelium and forms the primary lens fiber, HSP28 was observed in the apical and basal sides of the primary lens fiber. At stage 19, when the primary lens fiber attaches to the anterior lens epithelium, immunoreactivity to HSP28 appeared in the anterior lens epithelium. At stage 21, the anterior lens epithelium and the equator portion of the lens, where the secondary lens fiber is formed, were intensely immunoreactive to HSP28. Although alpha B-crystallin is thought to be one of the small HSPs, the distribution of HSP28 in the lenses of human embryos was different from that of alpha B-crystallin which we previously reported.

Gestational Age↗
PubMed1996

Suppression of interleukin-2 receptor expression on mouse CD4+ T cells by bovine kappa-caseinoglycopeptide.

Bovine kappa-caseinoglycopeptide (residues 106-169, CGP) completely inhibited the PHA-induced proliferation of mouse splenocytes when CGP was added simultaneously with PHA. The inhibitory effect, however, was reduced to about one-half when CGP was added after 24 h of cultivating the splenocytes with PHA or when anti-IL-1ra antibody was added simultaneously with PHA and CGP. On the other hand, CGP bound to mouse CD4+ T cells but not to CD8+ T cells. CGP suppressed IL-2 receptor expression of the PHA-stimulated mouse CD4+ T cells.

Animals↗
PubMed1996

Presence and localization of endothelin receptor in the rat ovary and its regulation by pituitary gonadotropins.

In the present study we examined the regulation of receptors for endothelin 1 (ET-1) in rat granulosa cells. We examined the localization and regulation of ET receptors in immature rat ovary and the effects of ET-1 on steroidogenesis in cultured rat granulosa cells. The ovaries used in autoradiography were derived from pregnant mare serum gonadotropin and human chorionic gonadotropin-treated immature rats. Granulosa cells were obtained from diethylstilbestrol-treated immature rats and incubated with 125I-ET-1. Granulosa cells were cultured with ET-1 in the presence or absence of ovine follicle-stimulating hormone. The concentrations of sex steroid hormones in conditioned media were measured by radioimmunoassay. The binding site for ET-1 was localized in the granulosa cells, but not in thecal and luteal cells. Follicle-stimulating hormone (FSH) induced a dose-dependent increase in specific binding for ET-1 to cultured rat granulosa cells. In contrast, luteinizing hormone (LH) induced a dose-dependent decrease in specific binding for ET-1 to cultured rat granulosa cells. Conversely, treatment with prolactin and several sex steroid hormones had no effects on the specific binding of ET-1. Treatment with ET-1 inhibited FSH-stimulated accumulation of progesterone and estradiol in cultured rat granulosa cells. The results indicate that both FSH and LH influence the expression of ET-1 receptor, and that ET-1 may play a regulatory role in the ontogeny of the granulosa cell.

Animals↗
PubMed1996

Cytokine modulation of inhibin secretion in cultured rat granulosa cells.

In the present study, we examined the effects of tumour necrosis factor alpha (TNF alpha) and interleukin-1 beta (IL-1 beta) on inhibin secretion by cultured rat granulosa cells using immunoblotting and two-site enzyme immunoassay for inhibin A (alpha-beta A dimer). FSH stimulated the secretion of the inhibin alpha-beta A dimer (32 kDa) by the cells in a dose-dependent manner. In addition to the predominant 32 kDa inhibin alpha-beta A dimer staining, staining of minor immunoreactive bands was also enhanced by FSH. TNF alpha alone did not have any effect on inhibin secretion. Immunoblot analyses using an antiserum against alpha-subunit and an antiserum against beta A-subunit revealed a dose-dependent inhibition by TNF alpha of FSH-stimulated secretion of inhibin by rat granulosa cells. Similarly, TNF alpha inhibited in a dose-dependent manner FSH-stimulated inhibin secretion when measured using a two-site enzyme immunoassay. IL-1 beta alone did not exert any effect on inhibin secretion but it inhibited FSH-stimulated inhibin release in a dose-dependent manner (using both immunoblotting and a two-site assay for inhibin A). The present observations suggest that TNF alpha and IL-1 beta inhibit gonadotrophin-stimulated inhibin production by cultured rat granulosa cells.

Animals↗
PubMed1996

Beyond category sorting and pleasantness rating: inducing relational and item-specific processing.

In most studies of relational and item-specific processing, category sorting and pleasantness rating have been the main procedures used to induce these two types of processing. Because the two types of processing have been studied in a wide range of memory phenomena (Hunt & McDaniel, 1993), it is strange that other tasks have not been proposed and tested. The present experiment demonstrates that equivalent results can be obtained with three relational processing tasks (category sorting, narrative construction, and relational imagery) and equivalent results with three item-specific processing tasks (pleasantness ratings, familiarity ratings, and single imagery).

Adult↗
PubMed1996

[Significance of hot shot in patients with unstable angina undergoing emergency coronary artery bypass graft surgery].

We investigated the efficacy of terminal warm blood cardioplegia (hot shot) in patients with cardioplegic techniques. From January 1991 through April 1993, 68 patients recieved hypothermic cardioplegia induced by cold modified St. Thomas' Hospital solution containing 10mg/L of diltiazem hydrochloride followed by intermittent infusion of the cold crystalloid solution or cold blood cardioplegia without hot shot. From May 1993 through December 1994, 65 patients recieved hot shot before removal of aortic cross-clamp following the hypothermic cardioplegia. The earlier group consisted of 51 patients with stable angina undergoing elective CABG and 17 patients with unstable angina undergoing emergency of urgent CABG. The later group consisted of 44 patients with stable angina and 21 patients with unstable angina. The unstable angina undergoing coronary artery bypass graft surgery (CABG) using antegrade incidence of perioperative myocardial infarction was significantly higher in patients with unstable angina without hot shot (35%) compared to those with stable angina with and without hot shot (2% and 4%, respectively) and those with unstable angina with hot shot (5%). The level of maximum creatine kinase-MB (IU/L) was significantly greater in patients with unstable angina without hot shot (134 +/- 26) compared to those with stable angina with and without hot shot (57 +/- 7 and 65 +/- 4, respectively) and those with unstable angina with hot shot (57 +/- 8). The doses of dopamine and dobutamine (mg/kg) administered during 48 hours after CABG was not different between patients with stable angina with and without hot shot (13.9 +/- 0.9 vs 13.9 +/- 0.9), but tended to be lower in patients with unstable angina with hot shot (13.7 +/- 1.3) compared to those without hot shot (18.6 +/- 2.1). Left ventricular stroke work index (g.m/m2/b) immediately after CABG was comparable between patients with stable angina with and without hot shot (40 +/- 2.0 vs 36 +/- 1.5), but significantly greater in patients with unstable angina with hot shot (39 +/- 2.3) compared to those without hot shot (29 +/- 2.2). These results suggest that hot shot may provide a significant benefit in myocardial preservation during CABG especially in patients with unstable angina.

Aged↗
PubMed1996

[MRSA-induced prosthetic valve endocarditis complicated by synthetic graft infection that did not respond to repeated vancomycin administration but improved after surgery].

We performed AVR and OMC in a 55-year-old male with ASR complicated by MS and ASO. Postoperatively, an ulcer formed on the left lower extremity, resulting in methicillin-resistant Staphylococcus aureus (MRSA) infection. Axillo-bilateral-femoral artery bypass was performed using synthetic grafts. However, infection developed in the anastomosis site, leading to MRSA sepsis. Since MRSA is highly susceptible to vancomycin (VCM), this drug was administered at a dose of 1.5 g/day. With negative conversion of MRSA, the infected wound healed, and the general status improved. However, after discontinuation of VCM administration, sepsis recurred. VCM administration was resumed with prolongation of the administration period and an increase in the dose. Drug administration was discontinued 3 times after 2-4 weeks each, but recurrence was observed each time. During this period, AR due to prosthetic valve endocarditis (PVE) developed. AVR and MVR were performed again, and the synthetic graft was left in place. However, after discontinuation of postoperative VCM administration, infection of the synthetic graft was also demonstrated. The graft was removed, and revascularization was performed by another route. The patient improved after these procedures. When MRSA-induced PVE or synthetic graft infection develops, the infectious foreign material should be completely removed at an early stage before progression of tissue destruction or ulcer formation even if antibiotics are effective.

Anti-Bacterial Agents↗
PubMed1995

Regulation of apolipoprotein B secretion in hepatocytes from Watanabe heritable hyperlipidemic rabbit, an animal model for familial hypercholesterolemia.

Regulation of apolipoprotein B-100 (apo B) secretion in the liver in familial hypercholesterolemia (FH) remains largely unknown. In a previous study, we developed a rabbit hepatocyte culture system and investigated a cellular mechanism which regulates apo B secretion from hepatocytes in response to cellular cholesteryl ester contents [18]. Using this system, in the present study, we investigated regulation of apo B secretion in hepatocytes from the Watanabe heritable hyperlipidemic (WHHL) rabbit, an animal model for FH. Incubation with low density lipoproteins (LDL) at concentrations of 50 or 200 micrograms/ml, which increased both cellular cholesteryl ester and apo B secretion significantly in normal rabbit hepatocytes, did not cause such increases in WHHL rabbit hepatocytes. However, when WHHL rabbit hepatocytes were incubated with LDL at a concentration of 500 micrograms/ml, a significant increase in cellular cholesteryl ester and apo B secretion was observed. The effect of the increase in cellular level of cholesteryl ester upon apo B secretion in WHHL rabbit hepatocytes was compatible with that in normal rabbit hepatocytes. Indeed, when WHHL rabbit hepatocytes were incubated with LDL at 1680 micrograms/ml, a concentration comparable to that of WHHL rabbit plasma, the amount of LDL degradation, cellular cholesteryl ester level, and level of apo B secretion were the same as those in normal rabbit hepatocytes that were incubated with LDL at 160 micrograms/ml, a concentration comparable to that of normal rabbit plasma. In summary, our present study suggests that, at a steady state with such a high plasma concentration of LDL, the hepatic cholesterol content in WHHL rabbits could be set at the same level as in normal rabbits. It was also shown that cellular cholesteryl ester contents had the same regulatory effect on apo B secretion in WHHL rabbit hepatocytes as in normal rabbit hepatocytes. Therefore, we conclude that in the presence of the genetic defect of the LDL receptor, plasma cholesterol in WHHL rabbit is maintained at a concentration such that apo B secretion is similar to that in normal rabbit.

Animals↗
PubMed1995

Independent regulation of sterol regulatory element-binding proteins 1 and 2 in hamster liver.

Two sterol regulatory element-binding proteins (SREBPs, designated SREBP-1 and SREBP-2), each approximately 1150 amino acids in length, are attached to membranes of the endoplasmic reticulum and nuclear envelope in human and hamster tissue culture cells. In the absence of sterols, soluble fragments of approximately 470 amino acids are released from both proteins by proteolytic cleavage. The soluble fragments enter the nucleus, where they bind to sterol regulatory elements in the promoters of genes encoding the low density lipoprotein receptor and 3-hydroxy-3-methylglutaryl CoA synthase, thereby activating transcription. Proteolytic processing of both SREBPs is blocked coordinately by sterol overloading and enhanced coordinately when sterols are depleted by treatment with an inhibitor of cholesterol synthesis. In contrast to these findings in cultured cells, the current data show that SREBP-1 and -2 are not coordinately regulated in hamster liver. In untreated animals the soluble fragment of SREBP-1, but not of SREBP-2, was detected by immunoblotting of a liver nuclear extract. Depletion of sterols by treatment with a bile acid-binding resin (colestipol) and a cholesterol synthesis inhibitor (mevinolin) led to a marked increase in the nuclear form of SREBP-2 and a reciprocal decline in the nuclear form of SREBP-1. These findings suggest that SREBP-1 is responsible for basal transcription of the low density lipoprotein receptor and 3-hydroxy-3-methylglutaryl CoA synthase genes in hamster liver and that SREBP-2 is responsible for the increased transcription that follows sterol depletion with a bile acid-binding resin and a cholesterol synthesis inhibitor.

Animals↗
PubMed1995

The LIM class homeobox gene lim5: implied role in CNS patterning in Xenopus and zebrafish.

LIM homeobox genes are characterized by encoding proteins in which two cysteine-rich LIM domains are associated with a homeodomain. We report the isolation of a gene, named Xlim-5 in Xenopus and lim5 in the zebrafish, that is highly similar in sequence but quite distinct in expression pattern from the previously described Xlim-1/lim1 gene. In both species studied the lim5 gene is expressed in the entire ectoderm in the early gastrula embryo. The Xlim-5 gene is activated in a cell autonomous manner in ectodermal cells, and this activation is suppressed by the mesoderm inducer activin. During neurulation, expression of the lim5 gene in both the frog and fish embryo is rapidly restricted to an anterior region in the developing neural plate/keel. In the 2-day Xenopus and 24-hr zebrafish embryo, this region becomes more sharply defined, forming a strongly lim5-expressing domain in the diencephalon anterior to the midbrain-forebrain boundary. In addition, regions of less intense lim5 expression are seen in the zebrafish embryo in parts of the telencephalon, in the anterior diencephalon coincident with the postoptic commissure, and in restricted regions of the midbrain, hindbrain, and spinal cord. Expression in ventral forebrain is abolished from the 5-somite stage onward in cyclops mutant fish. These results imply a role for lim5 in the patterning of the nervous system, in particular in the early specification of the diencephalon.

Amino Acid Sequence↗
PubMed1995

Histocytochemical and immunohistochemical studies related to the role of glycogen in human developing digestive organs.

To elucidate the role of glycogen in the epithelium of developing digestive organs, we investigated the appearance of glycogen and glycogen phosphorylase (GP) in these organs. We studied 64 externally normal human embryos at Carnegie stages 13-23 (5.1-28.0 mm in crown-rump length, 4-8 weeks of gestation) by histocytochemical staining for glycogen and immunohistochemical staining with antibodies against two isoenzymes of GP: brain-type (BGP) and muscle-brain-type (MBGP) GP. At stage 13, glycogen appeared in the epithelium of the digestive tract and the parenchyma of the pancreas. As development advanced, glycogen granules increased in number and size in these tissues, and they became evenly distributed in the epithelium of the digestive tract as either single particles or aggregates, as deduced by electron microscopy at late embryonic stages. Immunoreactivity specific both for BGP and for MBGP was detected in the digestive tract and the pancreas from stage 13. As development advanced, both BGP- and MBGP-immunoreactive cells increased in number and in immunoreactivity, and the number of MBGP-immunoreactive cells became larger than that of BGP-immunoreactive cells. By contrast, in hepatic cells, which serve as a major storage site for glycogen in adults, glycogen was detected only from stage 20, in smaller amounts, without formation of aggregates, and no immunoreactivity specific for BGP or MBGP was apparent throughout the embryonic stages examined. Thus, in the epithelium of the digestive tract and the parenchyma of the pancreas, but not in hepatic cells, the appearance and localization of GP coincided almost exactly with that of glycogen. These observations suggest that glycogen in the epithelium of the digestive tract and the parenchyma of the pancreas has not only been synthesized but also degraded from an early embryonic period and may, thus, be related to active cellular metabolism that is specific for embryonic development, including proliferation of the epithelium and interactions between epithelium and mesenchyme.

Digestive System↗
PubMed1995

Role of sodium pump activity in warm induction of cardioplegia combined with reperfusion of oxygenated cardioplegic solution.

Na+/K+ adenosinetriphosphatase (sodium pump) may play a key role in the prevention of reperfusion injury caused by Ca2+ overload. The present study was undertaken to investigate the role of sodium pump activity in warm induction of cardioplegia combined with reperfusion of oxygenated cardioplegic solution. Isolated and perfused rat hearts were subjected to 15 minutes of normothermic ischemia to produce a model of severely failing heart. The hearts then received myocardial preservation. Warm (37 degrees C) or cold (4 degrees C) oxygenated modified St. Thomas' Hospital solution was given for 5 minutes before and after 120 minutes of hypothermic cardioplegic arrest. Reduced myocardial pH during normothermic ischemia was adjusted toward the baseline level by administration of cold or warm oxygenated cardioplegic solution without a significant intergroup difference. Myocardial adenosine triphosphate levels decreased to less than 30% of the preischemic level during 15 minutes of normothermic ischemia, but were increased partly by induction of cold or warm oxygenated cardioplegia. Thus these metabolic indices failed to demonstrate the superiority of warm over cold oxygenated cardioplegia. Na+/K+ adenosinetriphosphatase activity in the membrane fraction was significantly stimulated by a cardioplegic dose of K+ with maximum activity at 16 mEq/L. The enzyme activity of the heart measured after normothermic ischemia was reduced to less than 50% of that in the nonischemic heart. Although warm induction of cardioplegia and reperfusion of oxygenated cardioplegic solution maintained Na+/K+ adenosinetriphosphatase activity at the preischemic level, the enzyme activity was abolished at 4 degrees C, which is the temperature used in cold cardioplegia. A subtoxic dose of ouabain (0.1 mmol/L) inhibited the enzyme activity of the heart undergoing this preservation regimen to approximately 50%. Warm induction and reperfusion of oxygenated cardioplegic solution showed significantly better recovery of isovolumic left ventricular function during reperfusion compared with that obtained with cold oxygenated cardioplegia. However, the beneficial effect of warm oxygenated cardioplegia on left ventricular function was compromised by inclusion of 0.1 mmol/L ouabain without a significant effect on myocardial metabolic parameters. These results suggest that stimulation of Na+ pump activity may account for the beneficial effect of warm induction and reperfusion of oxygenated cardioplegic solution in the energy-depleted heart.

Acid-Base Equilibrium↗
PubMed1995

Inhibition of proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells by bovine milk caseins and their digests.

The modulating effect of bovine milk casein components and their digests on the proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells induced or not induced by mitogens has been studied with a colorimetric assay using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. All the casein components and their digests tested had little mitogenic effect on the proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells. Intact kappa-casein significantly inhibited the proliferative responses of mouse spleen lymphocytes and Peyer's patch cells induced by mitogens such as lipopolysaccharide from Salmonella typhimurium, concanavalin A, phytohaemagglutinin and pokeweed mitogen. In contrast, intact alpha s1-casein and beta-casein had little effect. kappa-Casein had an inhibitory effect after digestion by pancreatin or trypsin, but not after pepsin or chymotrypsin digestion. Both pancreatin and trypsin digests of alpha s1-casein and beta-casein significantly inhibited the proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells induced by mitogens, whereas pepsin and chymotrypsin digests of both caseins were without effect. Moreover, the trypsin digest of each casein component had an inhibitory effect on mouse spleen lymphocyte proliferation in the absence of mitogen. Since trypsin is a major proteinase in pancreatin, the substrate specificity of trypsin seems to be important for the formation of the inhibitory peptides from casein components. These observations suggest that intact kappa-casein and some peptides formed from milk casein components by the action of trypsin may suppress the immune responsiveness of neonates.

Animals↗