Activation of adenylate cyclase by divalent cations and polyamines in saponin-treated Dictyostelium discoideum cells

Binding of an intrinsic agonist (cyclic AMP) to specific receptors on the cell surface induces transmembrane signals for the activation of adenylate cyclase in the cellular slime mold Dictyostelium discoideum. We found that stimulation by CaCl2, MgSO4 or polyamines having two to four positive charges induced the activation of adenylate cyclase in cells treated with saponin. The activation was roughly identical to the stimulation of the intrinsic agonist both in amount and in time course. The intact cells (saponin-untreated cells) responded to neither divalent cations nor polyamines. While saponin is known to have a detergent-like effect and to make the plasma membrane permeable, low molecular weight dyes did not penetrate the plasma membrane under our conditions for the saponin-treatment. Caffeine is known to inhibit the cAMP-induced activation of adenylate cyclase by blocking signal transduction, but not by acting directly on the enzyme [Brenner, M. and Thoms, S.D. (1984) Dev. Biol. 101, 136-146]. We found that caffeine inhibited the cation-induced activation. These results suggest that these divalent and polyvalent cations do not act directly on adenylate cyclase but that they mimic or induce the transmembrane activation signal for adenylate cyclase in the saponin-treated cells.

The sulphated carbohydrate-protein linkage region isolated from chondroitin 4-sulphate chains of inter-alpha-trypsin inhibitor in human plasma

Inter-alpha-trypsin inhibitor (ITI) in human plasma has a unique structural architecture composed of three polypeptide chains (H1, H2 and L chains), which are linked to each other through a chondroitin 4-sulphate chain. The structure of the carbohydrate-protein linkage region of the chondroitin 4-sulphate chain attached to the L chain was investigated. The peptide-chondroitin sulphate fraction was isolated by anion-exchange chromatography after exhaustive digestion with lysyl endopeptidase and then V8 protease. The chondroitin 4-sulphate chain was released from the peptides by beta-elimination using NaB3H4 and then digested with chondroitinase ABC. These treatments resulted in a single 3H-labelled hexasaccharide alditol fraction derived from the linkage region which had been associated with the L chain. Chemical and enzymatic analyses as well as fast-atom bombardment-mass spectrometry (FAB-MS) analysis revealed that the 3H-labelled hexasaccharide alditol had the following structure: delta HexA-alpha 1-3GalNAc(4-sulphate)beta 1-4GlcA beta 1-3Gal(4-sulphate)beta 1-3Gal beta 1-4Xyl-ol (where delta HexA is 4-deoxy-alpha-L-threo-hex-4-enepyranosyluronic acid and Xyl-ol is xylitol). The structure contained the novel 4-sulphated Gal residue, which was previously demonstrated in a linkage hexasaccharide isolated from chondroitin 4-sulphate of rat chondrosarcoma (Sugahara et al., J. Biol. Chem., 263, 10168-10174, 1988) and of whale cartilage (Sugahara et al., Eur. J. Biochem., 202, 805-811, 1991). The above disulphated hexasaccharide alditol was the only component detected in the linkage region fraction of the chondroitin 4-sulphate chain of ITI, which implies some biological significance of this novel structure.

Canal-expansive laminoplasty in 83 patients with cervical myelopathy. A comparative study of three different procedures

We have reviewed 83 patients who had undergone canal-expansive laminoplasty for the treatment of cervical myelopathy between 1982 and 1991. The procedures used for laminoplasty were a Z-plasty in 35 patients, unilateral laminoplasty in 19, and sagittal splitting of the spinous processes in 29. At an average follow-up of more than two years and five months, there were no significant differences in clinical results among the three operations, and excellent or good results were obtained in more than 70% of the patients. However, Z-plasty was the least preferable because this procedure had the longest operating time and the greatest intraoperative blood loss. The sagittal splitting procedure is recommended in routine laminoplasty in order to avoid complications at the site of osteotomy, and to allow simultaneous posterior fusion to be easily performed.

Amyloid bone cysts of the femoral neck. Impending fractures treated by curettage and bone grafting

We performed curettage and bone grafting of amyloid cysts of the femoral neck in five patients on long-term haemodialysis. All had had hip pain on weight-bearing. The duration of haemodialysis before the operation averaged 15 years and the average age of the patients was 53 years. All the large cystic lesions were located in the anterosuperior quadrant of the femoral neck. At operation, they were found to consist of fibrous tissue containing amyloid deposits. Postoperatively, all five patients had painless hips and the grafts had incorporated into the bone defects.

Amyloid bone cysts of the femoral neck. Impending fractures treated by curettage and bone grafting

We performed curettage and bone grafting of amyloid cysts of the femoral neck in five patients on long-term haemodialysis. All had had hip pain on weight-bearing. The duration of haemodialysis before the operation averaged 15 years and the average age of the patients was 53 years. All the large cystic lesions were located in the anterosuperior quadrant of the femoral neck. At operation, they were found to consist of fibrous tissue containing amyloid deposits. Postoperatively, all five patients had painless hips and the grafts had incorporated into the bone defects.

Analysis of a novel cyclic Amp inducible prespore gene in Dictyostelium discoideum: evidence for different patterns of cAMP regulation

The D7 cDNA clone hybridizes to a 2.8 kb mRNA which first appears at the mound stage of development in the cellular slime mold Dictyostelium discoideum. This gene which is cyclic AMP (cAMP) inducible and is expressed specifically in the prespore cells contains an open reading frame interrupted by only one intron. The predicted amino acid sequence indicates a novel prespore protein which differs from all of the previously described prespore proteins in that it contains no internal repeats and does not share any homology with any of the other prespore genes. The amino acid sequence predicts a protein of 850 amino acids with a molecular weight of 95,343 daltons and an isoelectric point of 4.25. The protein is very rich in glutamine (13.8%), asparagine (10.6%) and glutamic acid (10.4%) with one potential glycosylation site and 28 possible sites for phosphorylation. The amino terminus is hydrophobic with characteristics of a signal sequence while the entire carboxyl half of the protein is notable for its hydrophilicity. Comparison of cAMP regulation of the D7 gene with the regulation of two other cAMP regulated prespore genes, the PL3(SP87) gene and the Psa(D19), reveals some striking differences. Disaggregation in the presence of cAMP results in transient degradation of mRNA for all three genes. The transcription rate for the D7 and PsA(D19) genes remains relatively unaffected by disaggregation but there is a rapid although transient decline in the transcription rate of the PL3(SP87) gene. Although the accumulation of all three mRNAs is first detectable at mound stage, transcription of the D7 and PsA(D19) genes is detected earlier in development, at rippling aggregate stage several hours prior to the earliest time when transcription of the PL3(SP87) gene is detected. Analysis of the promoter region of the D7 gene reveals three CA like boxes flanked by direct repeats as well as four G rich regions that may serve as regulatory elements.

Pancreastatin-like immunoreactivity of cerebrospinal fluid in patients with Alzheimer type dementia: evidence of aberrant processing of pancreastatin in Alzheimer type dementia

The concentrations of pancreastatin-like immunoreactivity (PST-LI) of the cerebrospinal fluid (CSF) were measured in the patients with Alzheimer type dementia (ATD) and in age-matched normal subjects. The mean PST-LI concentration in the CSF of ATD patients was significantly lower than that of normal subjects. Gel chromatographic analysis revealed that the main PST-LI peak of ATD's CSF eluted at molecular weight (MW) 13.5 kDa. However, the age-related change of the molecular forms of PST-LI in CSF was observed in normal subjects as following; PST-LI in neonatal CSF showed one peak at MW 13.5 kDa, that of 16-64-year-old showed two peaks at MW 13.5 and 5.4 kDa, however, only one main peak was shown at MW 5.4 kDa in the CSFs of 72-85-year-old. These findings suggest that the production of PST-LI was decreased and the proteolytic cleavage, which should process big PST to PST (1-52) in normal subjects, was altered to that of neonatal type in the CNS of the patients with ATD.

Unique change of pancreastatin-like immunoreactivity in cerebrospinal fluid by aging

Using a specific antiserum for the C-terminal glycine amide region of human pancreastatin (PST), pancreastatin-like immunoreactivity (PST-LI) was measured in cerebrospinal fluid (CSF) from 447 subjects (368 +/- 10.8 pmol/l, mean +/- S.E.M.) free from endocrine diseases. The CSF contents of PST-LI showed a mountain-shape type change which peaked at 40 years of age. The highest concentration was found in the group of ages 40-49 years old (412 +/- 22.9 pmol/l) and the lowest concentration was found in the group of ages 80-89 years old (293.2 +/- 45.2 pmol/l) among various age groups. Gel chromatographic examination revealed the presence of two major forms (MW 13,500 and 5,400) of PST-LI in CSF. Because of the character of this antibody, the large molecular form is possibly an N-terminally elongated PST and the other may be PST-52. This may be the first report on the unique age-related change of PST concentration in CSF.

Induction of antibiotic production by protease in Bacillus brevis (ATCC 8185)

Bacillus brevis (ATCC 8185) produces an antibiotic peptide, linear gramicidin, in the early stationary growth phase. Since we observed that preculture in milk medium is essential for production of the antibiotic in broth medium, we studied the role of the preculture in the antibiotic production. We found that addition of the supernatant of the precultured milk medium was sufficient to induce gramicidin production in broth medium. Fresh milk medium had no effect. The effector substance in the overnight cultured milk medium was labile at both acidic and alkaline pH and was destroyed by heat. We also found that addition of a protease (for example, bovine pancreas chymotrypsin or Streptomyces griseus protease) instead of the supernatant could induce the gramicidin production. Addition of Mn2+ was not required for the protease-induced production of gramicidin. It is known that B. brevis cells secrete protease into milk medium. But neither use of the protease-pretreated broth medium nor addition of casamino acids to broth medium induced gramicidin production. These results suggest that B. brevis cells secrete a factor for linear gramicidin production, that the inducing factor is protease and that the target of the protease is a substance(s) produced by the bacteria.

Anterior cervical fusion with the Caspar instrumentation system

We reviewed 106 consecutive patients who had undergone anterior cervical fusion with the Caspar instrumentation system between 1984 and 1989. Preoperative diagnoses were cervical spondylosis in 73 patients, a traumatic lesion in 12, ossification of the posterior longitudinal ligament in 9, cervical disc herniation in 6, and tumour or miscellaneous lesions in 6. In the 106 patients, 56 had two levels fused and 27 had three levels fused. At an average duration of follow-up of 4 years and 7 months, nonunion occurred in 3 of the 83 patients with multiple level fusions. Screw loosening occurred in 8 of the 106 patients, but there was no oesophageal perforation.

[Face recognition in preschool children: effects of familiarity, facial expression and angle of view]

The purpose of this study was to investigate the face recognition processes in preschool children. Two experiments were carried out to examine the effects, on face recognition, of familiarity, facial expression and angle of view of faces as well as changes or no changes in facial expression and/or angle of view occurring between the first presentation and the subsequent recognition test. The subjects were 188 five- and six-year old children. In Experiments 1 and 2, half of the faces were highly familiar to the subjects, and the remaining half unfamiliar to them. In Experiment 1, the facial expressions (e.g., smiling or serious) were either changed or unchanged. In Experiment 2, the facial expressions or angles of view (e.g., full-face views or three-quarter views of faces) were either changed or unchanged. The major findings were that the familiar faces and the smiling faces were recognized more correctly than the unfamiliar faces and the serious faces respectively. The results were discussed in terms of 'identity-specific semantic codes' and 'visually-derived semantic codes'.

Activation of proximal tubular Na(+)-H+ exchange by angiotensin II

Stimulation of Na(+)-H+ exchange by angiotensin II (ANG II) was characterized in renal proximal tubular cells. Rabbit proximal nephron segments were incubated in the presence or absence of ANG II (5 x 10(-10) M), after which brush-border membrane vesicles (BBMV) were isolated and assayed for Na(+)-H+ antiporter activity using the acridine orange technique. Both the affinity (for sodium) and capacity of the carrier were elevated significantly (P less than 0.05) within 15 min of incubation with ANG II. To determine whether the stimulation of transport capacity involved a change in Na(+)-H+ antiporter density in the luminal membrane, binding of tritiated 5-(N-methyl-N-isobutyl)amiloride ([3H]MIA) was measured in BBMV derived from control and ANG II-treated nephron segments, following maximal stimulation. This demonstrated a significant (P less than 0.05) increase in the maximal specific binding (Bmax) of [3H]MIA binding in the ANG II-treated group compared with control, of a magnitude sufficient to account for the observed change in maximal velocity (Vmax). The data indicate that the Vmax effect is caused by an apparent increase in the number (density) of active Na(+)-H+ carriers present in the luminal membrane. Finally, to test the possibility that the observed kinetic change involves an exocytic mechanism, the effect of colchicine on ANG II-stimulated antiporter activity was examined. The increase in Vmax due to ANG II was blocked by the addition of 0.5 mM colchicine to the incubation medium, whereas colchicine alone had no significant effect on the Vmax of Na(+)-H+ kinetics.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of .ALPHA.1-adrenoceptor blockade on the left ventricular force-length relationship in dogs

We used the left ventricular (LV) end-systolic force-diameter (Fes-Des) relation to evaluate the effect of an alpha1-adrenoceptor antagonist (bunazosin hydrochloride) on the contractility of the beta-blocked left ventricle. Nine adult mongrel dogs were instrumented with ultrasonic crystals to measure LV diameter and a micromanometer to measure LV pressure. Beta-adrenergic and vagal blockade was induced with intravenous propranolol (2 mg/kg) and atropine (0.2 mg/kg), respectively, and preload was decreased by inferior vena caval occlusion. The slope (Ec) and extrapolated diameter intercept (Do) of the LV Fes-Des relation were derived from end-systolic data obtained in the control state (after beta-blockade) and after bunazosin infusion (1 mg/kg). Ec was used as a new index of LV contractility. After bunazosin infusion, the heart rate and Ec were decreased by 7 and 22%, respectively, in comparison with the control state, whereas Do did not change. These results indicate that alpha1-adrenoceptor blockade significantly reduces myocardial contractility in the beta-blocked canine heart, perhaps by decreasing the intracellular calcium concentration and/or myosin ATPase activity.

Reducing reagent-induced activation of adenylate cyclase in the cellular slime mold, Dictyostelium discoideum

Binding of an intrinsic agonist (cAMP) to specific receptors on the cell surface induces transmembrane signals for activation and desensitization (adaptation and down regulation) of adenylate cyclase in the cellular slime mold, Dictyostelium discoideum. It is generally believed that dithiothreitol (DTT) induces the activation through interaction between the receptor and gradually accumulated cAMP, since DTT is known to inhibit cAMP-phosphodiesterase which degrades cAMP. In the present paper, we investigated the mechanism of activation of adenylate cyclase by the thiol-reducing agents, DTT and 2,3-dimercapto-1-propanol (BAL). We found that BAL activated adenylate cyclase transiently even under conditions where the intrinsic agonist supersaturated the cAMP-receptors and competitively inhibited phosphodiesterase. This result is inconsistent with the generally accepted notion. We conclude that BAL has an independent effect from those of the intrinsic agonist (cAMP) and phosphodiesterase in activation of adenylate cyclase. Since BAL could induce activation just after the activation induced by a supersaturating concentration of the intrinsic agonist had ceased, the independent effect of BAL is not a simple enhancement of the cAMP-induced activation. Our result also suggests that the cAMP-induced adaptation (but not down regulation) suppresses the BAL-induced activation while BAL itself does not induce adaptation to cAMP or BAL. We propose that the thiol-reducing reagent induces or modifies the transmembrane activation signal for adenylate cyclase.

Reducing reagent-induced activation of guanylate cyclase in the cellular slime mold, Dictyostelium discoideum

Binding of folic acid (an intrinsic agonist) to the cell surface receptors evokes transmembrane signals for activation and adaptation of guanylate cyclase in Dictyostelium discoideum. The activation signal activates this enzyme and then the adaptation signal terminates the activation. As a result, these two signals cooperatively induce a transient activation of guanylate cyclase. We investigated transmembrane signal transduction for guanylate cyclase using 2,3-dimercapto-1-propanol (BAL, a thiol-reducing reagent) since BAL induces or modifies the transmembrane signal(s). We found that BAL induced prolonged or continuous activation of guanylate cyclase. Thus, the mode of the activation is drastically different (transient versus continuous) between folic acid and BAL. We also found that the BAL-induced continuous activation was not observed when the cells were stimulated with BAL + folic acid, while folic acid + BAL transiently induced more cGMP accumulation than folic acid alone. We lastly showed that K252a, a protein kinase inhibitor, enhanced both the folic acid-induced and the BAL-induced activation of guanylate cyclase. Our results suggest that BAL induces or mimics the activation signal for guanylate cyclase. The lack of termination in the BAL-induced activation suggests that BAL does not induce the adaptation signal or that the adaptation does not inhibit the BAL-induced activation. The former possibility is more likely since folic acid suppresses the BAL-induced continuous activation. The effect of K252a suggests that protein phosphorylation plays a role in suppression of guanylate cyclase.

[Acute megakaryoblastic leukemia with leukemia cutis, meningeal leukemia, and myelofibrosis]

A 64-year-old man was admitted to our hospital with leukopenia. On admission, leukocyte count in the peripheral blood was 1,600/microliters, containing 24.5% blasts of lymphoid appearance, which were negative for myeloperoxidase. A bone marrow aspiration showed hypoplasia with increased blasts (31.6%). The blasts were ultrastructurally positive for platelet peroxidase (PPO) and positive for platelet membrane glycoprotein IIb/IIIa complex. A diagnosis of acute megakaryoblastic leukemia was made. Chemotherapy with behenoyl-ara C (BH-AC) (150 mg/day) was transiently effective. However, after three months, numerous nodules without itching appeared over the entire body, particularly on the anterior chest. A biopsy of the skin lesion revealed a diffuse fibrosis with infiltrations of the blasts. Bone marrow aspirations were dry tap, and a bone marrow biopsy showed marked myelofibrosis. Then, severe headache, vomiting, and loss of consciousness developed, and a lumbar puncture revealed infiltrations of blasts. Although methotrexate was intrathecally injected, he died due to the respiratory failure. As far as we know, a case of acute megakaryoblastic leukemia with leukemia cutis and meningeal leukemia is quite rare. In addition, it is interesting that megakaryoblastic leukemia was accompanied with both the fibrosis of skin and the myelofibrosis.

Low-Temperature Properties of Hydrogenated Nitrile Rubber (HNBR)

HNBR, hydrogenated nitrile rubber, is a heat-, oil-, and fuel-resistant elastomer produced by the selective hydrogenation of NBR. As shown in Table I, HNBR is a highly saturated nitrile elastomer consisting of units of acrylonitrile, ethylene, unsaturated butadiene, and hydrogenated vinyl butadiene. The acrylonitrile gives excellent oil resistance, fuel resistance, and high tensile strength to NBR. The ethylene provides not only excellent rubber elasticity, heat resistance, chemical resistance, and ozone resistance, but also good low-temperature flexibility. The presence of a small unsaturated portion in the butadiene unit makes possible the easy vulcanization of HNBR with either sulfur or peroxide. The vinyl butadiene segments (6–8%) are preferentially hydrogenated at the beginning of the reaction and assist in maintaining the amorphous nature of the elastomer. The low-temperature flexibility of ordinary NBR varies in inverse proportion to its acrylonitrile content. Therefore, low-acrylonitrile NBR has better low-temperature flexibility than high-acrylonitrile NBR. The low-temperature properties of HNBR are different than those of NBR. This paper will show the relation between the acrylonitrile content and degree of hydrogenation and the glass-transition temperature (Tg) and low-temperature flexibility of HNBR. The Tg and low-temperature flexibility as measured by the TR-test and Gehman Torsional Stiffness test of HNBR showed the different behaviors for the various degrees of hydrogenation and acrylonitrile contents. Conversely, the brittle temperature of HNBR becomes lower with an increase in degree of hydrogenation. This paper also describes the effects of polymer composition and of various plasticizers on the low-temperature flexibility of HNBR.

A case of leiomyoblastoma (epithelioid leiomyosarcoma) of the greater omentum

A 59-year-old male complained of a palpable abdominal mass which was revealed to be a primary omental tumor by means of abdominal ultrasonography, computed tomography, angiography and laparoscopy. Histological examinations of the surgically resected tumor further disclosed leiomyoblastoma with positive stainings of both vimentin and desmin, markers for mesenchymal cells and for muscle cells, respectively. He has been well for 2 years since resection, without any relapse or distant metastasis of the tumor. Leiomyoblastoma of the greater omentum is very rare, and is important to distinguish from extraluminal tumor of the abdomen.

Regulation of guanylate cyclase by a guanine nucleotide binding protein, G alpha 2, in Dictyostelium discoideum

Binding of cyclic AMP (cAMP) to the cell surface receptor induces a transient activation of guanylate cyclase in Dictyostelium discoideum. A frigid mutant (HC85) which lacks G alpha 2, a guanine nucleotide binding protein, does not respond to cAMP. We found that 2,3-dimercapto-1-propanol (BAL) induced a continuous activation both in the frigid and in its parents. Therefore, the BAL-induced continuous activation of guanylate cyclase is independent of G alpha 2. We also found that cAMP enhanced the BAL-induced continuous activation in the frigid mutant. This result suggests that an unidentified signal transduction mechanism from the cAMP-receptor besides the one involving G alpha 2 plays a role in the enhancement of activation. Lastly, we found that the BAL-induced continuous activation was terminated by cAMP in the parental strain, but not in the frigid mutant. Therefore, the cAMP-induced suppression on the BAL-induced continuous activation is mediated through G alpha 2.

Inhibition by EDTA and enhancement by divalent cations or polyamines of the dithiothreitol-induced activation of adenylate cyclase in the cellular slime mold, Dictyostelium discoideum

Binding of cAMP to cell surface receptors evokes the transient activation of of adenylate cyclase in Dictyostelium discoideum. Dithiothreitol is also known as an activator of this enzyme. We found that the dithiothreitol-induced activation was specifically enhanced by extracellular polyamines or divalent cations. Furthermore, EDTA, a chelating agent of divalent cations, completely inhibited the dithiothreitol-induced activation of adenylate cyclase while EDTA did not inhibit the cAMP-induced activation. The inhibition was nullified by addition of polyamines or divalent cations. These results suggest that extracellular polyamines and divalent cations play a specific role in the dithiothreitol-induced activation of adenylate cyclase.

[Pharmacological study on citrus fruits. II. Anti-allergic effect of fruit of Citrus unshiu MARKOVICH (2). On flavonoid components]

A study was carried out to clarify the active component of green fruit of Citrus unshiu MAKOVICH on the type I allergic reaction. The flavonoid component, isolated from its methanolic extract, hesperidin, was found to inhibit histamine release from peritoneal mast cells of rats induced by compound 48/80. Forty eight-hour homologous passive cutaneous anaphylaxis (PCA) in intact rats was significantly inhibited by the oral administration of hesperidin. However, the anti-allergic action on PCA was not observed in adrenalectomized rats. These results suggests that hesperidin is an effective component of the fruit of Citrus unshiu with the anti-allergic action against the type I reaction.

Role of a guanine nucleotide binding protein, G alpha 2, in regulation of adenylate cyclase in Dictyostelium discoideum

Two substances, cAMP and 2,3-dimercapto-1-propanol (BAL) are known to induce transient activation of adenylate cyclase in Dictyostelium discoideum. A frigid mutant (HC85) has a deletion in a gene for G alpha 2, a guanine nucleotide binding protein and cannot activate the cyclase in response to cAMP. We found that BAL induced activation in the frigid mutant. This result suggests that the BAL-induced activation is independent of G alpha 2 and that BAL mimics a role of activated G alpha 2. We also found that cAMP promoted the BAL-induced activation. This result suggests that cAMP plays a role in activation through a mechanism in which G alpha 2 is not involved. We lastly showed that continuous cAMP stimulation could not inhibit the BAL-induced activation in the frigid mutant. Since the cAMP-induced inhibition observed in the wild type strain (NC4) proceeds with the time course identical to the cAMP-induced adaptation (Oyama, submitted), this result suggests that G alpha 2 is involved in adaptation of adenylate cyclase.