The cell envelope structure of the lipopolysaccharide-lacking gram-negative bacterium Sphingomonas paucimobilis

From the cell envelope preparation of Sphingomonas paucimobilis two membrane fractions with different densities were separated by sucrose density gradient ultracentrifugation. The high-density fraction contained several major proteins, phospholipids, and glycosphingolipids, which are the only glycolipids of this lipopolysaccharide-lacking gram-negative bacterium. The low-density fraction showed many minor bands of proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and NADH oxidase activity was localized in this fraction. Combined with morphological data of vesicles formed by these membrane fractions, the high-density and low-density fractions were proposed to be an outer membrane and a cytoplasmic membrane, respectively. The localization of the glycosphingolipid was investigated also by means of immunoelectron microscopic analysis using a glycosphingolipid-specific antibody. The glycosphingolipid was shown to localize at the cell envelope, and the antigenic sugar portion was exposed to the bacterial cell surface. From these results the glycosphingolipid was assumed to have a function similar to that of the lipopolysaccharide of other gram-negative bacteria.

[The effects of short and long duration of hypothyroidism on prolactin secretion in rats]

The aim of the present study was to evaluate the time-dependent effect of an experimentally induced hypothyroid state on prolactin (PRL) secretion in rats. Treatment with radioactive iodine and propylthiouracil (PTU) resulted in reduced serum concentrations of total thyroxine and triiodothyronine, and increased serum TSH concentrations in rats one week after the start of the treatment. Basal serum PRL concentrations were not significantly altered in 1-, 2- and 4-week hypothyroid rats, whereas in 8-week hypothyroid rats, serum PRL concentrations were significantly reduced and remained depressed throughout 24 weeks of PTU ingestion. The PRL response to i.p. administration of haloperidol (0.5mg/kg) was significantly reduced after one week of PTU ingestion. When the duration of hypothyroidism was increased, there was a progressive fall in the PRL response to haloperidol that reached the lowest value after 12 weeks of PTU ingestion. The PRL response to an i.v. bolus injection of vasoactive intestinal peptide (VIP, 150 mu g/kg) was markedly reduced in hypothyroid rats after one week of PTU ingestion and reached the lowest value after two weeks. The PRL response to VIP was progressively recovered after treatment for 4 weeks with PTU, and reached the highest value in 24-week hypothyroid rats. However, the PRL response to VIP in 24-week hypothyroid rats was significantly lower than that in euthyroid rats. Serum PRL response to an i.v. bolus injection of beta -endorphin (450 mu g/kg) was significantly reduced in 8-week hypothyroid rats. Dopamine (DA) concentrations in the pituitary and the hypothalamus were not significantly altered in 2-week hypothyroid rats. In contrast, DA concentrations were significantly increased in both the pituitary and hypothalamus in 8- and 24-week hypothyroid rats. These findings observed in hypothyroid rats were reversed by the administration of thyroxine and triiodothyronine for 9 days. The present results support a modulatory role for thyroid status in regulating the concentration of DA in the pituitary and the hypothalamus, and consequently on PRL secretion by the pituitary. This suggests that PRL releasing factors do not appear to play a major role in PRL secretion in hypothyroid rats. These data also indicate that alterations in PRL secretion and DA concentrations in the pituitary and the hypothalamus in the hypothyroid state become more prominent as the duration of hypothyroidism increases.

[Adult case of bronchial asthma induced by chironomid midges]

A 48-year-old woman who was diagnosed to have bronchial asthma induced by chironomid midges is reported. In spring of 1985, massive growth of chironomid midges occurred in the river beside her house. Since then, moderate growth has occurred in every spring or summer. She had wheezing attacks every May or June since June 1986. On May 2, 1991, she was hospitalized because of exacerbation of wheezing and dyspnea. Wheezing attacks were improved by appropriate medical treatment during hospitalization. Examination was performed during the state of stable clinical symptoms. RAST scores to Chironomus thummi thummi (CTT) and Chironomus plumosus (CP) were 4 and 3, respectively. Allergic skin reaction showed the threshold dilution of CP of 10(-6). CP skin test concomitantly provoked a mild acute asthma attack. The midges found swarming around her house were identified as Chironomus nippodorsalis. According to her clinical history and allergic skin reactions followed by acute asthmatic attack, this patient was diagnosed to have bronchial asthma induced by chironomid midges. Chironomid midge can be one of the inhalant allergens in adults.

[Resuscitation from experimentally induced hemorrhagic shock with hypertonic saline (effects on thoracic duct lymph flow and tissue oxygen tension)]

We compared the effect of hypertonic salt solution (7.2%, HS) with that of normal saline (NS) and lactated Ringer's solution (LR) for the treatment of hemorrhagic shock. We monitored hemodynamic parameters, thoracic duct lymph flow, and tissue oxygen tension over 3 hours after hemorrhage. Twenty-seven anesthetized mongrel dogs (0.5% halothane) were bled to an aortic pressure of 60 mmHg for 90 min following 40 mmHg for 30 min and then they were resuscitated with each solution. In NS group, the volume transfused was twice the bled volume, and in other two groups, each solution was transfused providing equal amounts of sodium as NS group. We found that hemodynamics were restored in HS group as well as in other two groups. On the other hand, thoracic duct lymph flow and tissue oxygen tension of renal cortex and liver increased significantly over other two groups. We conclude that small volume resuscitation with 7.2% NaCl may be effective in the initial treatment of hemorrhagic shock from the view of tissue circulation in vital organs.

Limitation of stunning in dog myocardium by nucleoside and nucleotide mixture, OG-VI

BACKGROUND

OG-VI is a nucleoside-nucleotide solution composed of 30 mM inosine, 30 mM cytidine, 30 mM sodium 5'-guanylate, 22.5 mM uridine, and 7.4 mM thymidine. It is expected to enhance the efficacy of intravenous hyperalimentation in surgically stressed patients. One of the main causes of ischemic myocardial damage is loss of adenine nucleotides from heart cells. The aim of the present study, therefore, was to examine the effect of OG-VI on myocardial mechanical function and energy metabolism in stunned myocardium.

METHODS

Pentobarbital-anesthetized dogs were subjected to 20 min ligation of the left anterior descending (LAD) coronary artery, followed by reperfusion for 30 min. OG-VI at 0.1 or 0.2 ml/kg/min or saline was infused from the left femoral vein throughout the experiment. The tissue levels of high-energy phosphates in the hearts were determined after 30 min reperfusion.

RESULTS

LAD flow, first derivative of left ventricular pressure (LVdp/dt), and segment function were increased by OG-VI in a dose-dependent manner. OG-VI infusion resulted in a significant improvement in LVdP/dt and segment shortening in the ischemic/reperfused myocardium compared with saline infusion. The levels of segment shortening with saline, 0.1, and 0.2 ml/kg/min OG-VI after reperfusion for 30 min were -0.3, 75, and 82% of the preligation levels, respectively. The tissue level of adenosine triphosphate (ATP) after reperfusion in OG-VI-infused animals was significantly higher than that in saline-infused animals.

CONCLUSION

OG-VI has a positive inotropic action, and its infusion results in a marked cardioprotective effect in stunned myocardium associated with the restoration of tissue ATP level.

[Measurements of serum pituitary hormones and dynamic tests to evaluate the pituitary functions]

Hormones produced by the anterior pituitary have conventionally been measured in the serum by radioimmunoassays (RIA), whereas more sensitive immunoradiometric assays (IRMA) have now been developed and are replacing RIA. Dynamic tests (stimulatory tests and suppression tests) rather than single and random determinations are often important tools in the study of pituitary functions. Stimulatory tests (such as glucagon plus propranolol test for growth hormone and water deprivation test for arginine-vasopressin) are used to evaluate hypofunction and suppression tests (such as dexamethasone suppression test for adrenocorticotrophic hormone) are used to investigate hyperfunction. This chapter, mainly dealing with representative dynamic tests, describes test protocols and how to interpret test results.

Regulation of 18-oxocortisol and 18-hydroxycortisol by the renin-angiotensin system and ACTH in man

Based on urinary excretion studies the secretion of the cortisol derivatives, 18-oxocortisol and 18-hydroxycortisol are believed to be regulated by ACTH and to a lesser degree by the renin-angiotensin system. Plasma concentrations of 18-oxocortisol and 18-hydroxycortisol were measured during the simultaneous activation of the renin-angiotensin system and inhibition of ACTH secretion. Five healthy male subjects consuming a sodium diet ad libitum were studied. Blood was drawn at 0800 h after 1 h in the supine position. In the first set of experiments, the subjects remained in the supine position from 0800 to 1000 h with or without the oral administration of 2 mg dexamethasone at 0800 h. In the second set of experiments the subjects were placed in the upright position after drawing the 0800 h sample. The subjects were studied with and without dexamethasone administered at 0800 h. Blood was drawn again at 1000 h. Plasma levels of 18-oxocortisol, 18-hydroxycortisol, ACTH, plasma renin activity (PRA), cortisol, aldosterone and 18-hydroxycorticosterone were measured by radioimmunoassay. None of these parameters changed during the 2 h in the supine position. 18-Oxocortisol, 18-hydroxycortisol, aldosterone, 18-hydroxycorticosterone and PRA increased, but ACTH and cortisol did not change when the subjects were placed in the upright position. After dexamethasone administration, 18-oxocortisol, 18-hydroxycortisol, cortisol, aldosterone and 18-hydroxycorticosterone decreased in the supine position and no increase occurred in 18-oxocortisol, 18-hydroxycortisol and 18-hydroxycorticosterone in the upright position. PRA and aldosterone increased and ACTH and cortisol decreased in these subjects. 18-Oxocortisol and 18-hydroxycortisol were more dependent on ACTH regulation and less on the renin-angiotensin system than aldosterone.

Protective effect of dihydroheptaprenol in combination with vaccine to experimental Actinobacillus pleuropneumoniae infection in guinea pigs and pigs

We investigated the effects of dihydroheptaprenol (DHP) on resistance of guinea pigs and pigs inoculated with Actinobacillus pleuropneumoniae (Apn) vaccine to subsequent challenge with Apn. Guinea pigs with complement-fixation (CF) antibody titers of 1:8 and 1:16 after intramuscular (i.m.) inoculation with inactivated Apn vaccine showed enhanced resistance to intraperitoneal (i.p.) infection with a homologous Apn strain (5 x 10(10) CFU/animal) when injected with DHP (20 mg/kg, i.m.) on the day before infection. The survival rates of the control, vehicle (lecithin solution without DHP), and DHP groups were 33%, 37%, and 63%, respectively, and that of the DHP group was significantly higher than the rates of the other groups (P < 0.05). Pigs with CF antibody titers of 1:8 and 1:16 after i.m. inoculation with inactivated Apn vaccine showed enhanced resistance to intratracheal infection with 5 x 10(10) CFU of Apn when injected with DHP (1, 2.5, or 5 mg/kg, i.m.) on the day before infection. The survival rates of the control, vehicle, DHP 1 mg/kg, DHP 2.5 mg/kg, and DHP 5 mg/kg groups were 37%, 38%, 47%, 60%, and 73%, respectively, and pigs given DHP at a dose of 5 mg/kg showed a significantly higher survival rate than the vaccinated control pigs (P < 0.05). The protective effect of DHP in vaccinated guinea pigs and pigs suggests that phagocytosis and bactericidal activity may be enhanced by this agent, depending on some opsonification effect on Apn antibody.

[Effects of cilostazol, a cyclic AMP phosphodiesterase inhibitor, on pulmonary vascular tone]

We examined the effect of Cilostazol, a cyclic AMP phosphodiesterase inhibitor, rat isolated pulmonary arterial ring tone. Cilostazol dilated pulmonary arterial rings pre-contracted with 10(-6) M phenylephrine in a dose-dependent manner (ED50 3.00 x 10(-6) M). This vasodilatory effect of Cilostazol was not affected by pretreatment with meclofenamate (10(-5) M), mechanical endothelium denudation, methylene blue (10(-5) M) or nitro-L-arginine (2 x 10(-4) M). The vasodilatory effect of Cilostazol on rat thoracic aortic rings was stronger than that on rat pulmonary arterial ring (ED50 1.89 x 10(-6) M). Cilostazol (10(-6) M-10(-4) M) inhibited hypoxic contraction of rat pulmonary rings in a dose-dependent manner. Our experimental data indicated that Cilostazol caused vasodilation regardless of vascular endothelium function and inhibited hypoxic contraction due to inhibition of cyclic AMP phosphodiesterase.

Changes in CA125 release and surface expression caused by drugs in uterine cervix adenocarcinoma cells

The effect of drugs on the release of CA125 antigen and the binding of anti-CA125 monoclonal antibody (MoAb) to malignant cells was evaluated in vitro. TMCC-1, uterine cervical adenocarcinoma cells, were exposed to dexamethasone (DEX), sodium n-butyrate (NaB), dibutyryl cyclic AMP (dbcAMP), retinoic acid (RA), calcitriol (VD3), and interferon-gamma (IFN-gamma). NaB, RA and VD3 increased CA125 release per cell and 125I-labeled anti-CA125 MoAb binding to the cells. DEX also increased the 125I-labeled anti-CA125 MoAb binding to the cells, and CA125 antigen release per cell was also slightly increased. IFN-gamma suppressed both CA125 release and 125I-labeled MoAb binding. A combination of DEX, VD3 and RA and increased the binding of MoAb to TMCC-1 cells, but the amount of bound MoAb was not significantly different from that obtained by single drug treatment. DbcAMP had no significant effect on enhancing MoAb binding. Drugs can increase the binding of anti-CA125 MoAb to malignant cells and they may be applied to increase the tumor uptake of radiolabeled MoAbs in vivo.

Total parenteral nutrition in posthepatectomy patients

Blood biochemical and nutritional metabolism indices were examined in eight patients who received infusion containing glucose, fructose, and xylitol in a 4:2:1 ratio (group GFX) after liver resection compared with those in six patients who received only glucose (group G). Preoperative patient-selection criteria consisted of a parabolic oral glucose tolerance test level over time, a total activity of coagulation factors II, VII, and X of > or = 60%, and an indocyanine green disappearance rate (ICG K) of > or = 0.13. Total parenteral nutrition (TPN) was started on the 3rd postoperative day. Levels of blood biochemical indices, rapid-turnover proteins, and urinary 3-methylhistidine were measured, and amino acids and nitrogen balance were analyzed preoperatively and on the 2nd, 5th, and 7th postoperative days. In group GFX, serum glutamic oxaloacetic transaminase and glutamic pyruvic transaminase levels decreased soon after TPN was begun, being 47 +/- 8 and 84 +/- 14 U/L, respectively, on the 7th postoperative day. This level was significantly lower (p < 0.05) than that in group G on the same day (94 +/- 18 and 141 +/- 22 U/L, respectively). There was no difference between the two groups in levels of rapid-turnover proteins or in Fischer ratio of amino acids. Urinary 3-methylhistidine level decreased soon after TPN in group GFX. Nitrogen balance became positive on the 7th postoperative day in group GFX, whereas it remained negative until the 7th postoperative day in group G.(ABSTRACT TRUNCATED AT 250 WORDS)

Increase in [3H]cAMP binding sites and decrease in Gi alpha and Go alpha immunoreactivities in left temporal cortices from patients with schizophrenia

To search for possible alterations in second messenger systems in the temporal cortex (Brodmann's area 22) of patients with schizophrenia, we measured the binding activities of [3H]adenosine 3',5'-cyclic monophosphate ([3H]cAMP) and [3H]4 beta-phorbol 12,13-dibutyrate ([3H]PDBu) which can label the regulatory subunit of cAMP-dependent protein kinase (protein kinase A) and the regulatory domain of Ca2+/phospholipid-dependent protein kinase (protein kinase C), respectively. We also immunoquantified the variable subunits of guanine nucleotide binding proteins (G-proteins), using specific polyclonal antisera against Gs alpha, Gi alpha and Go alpha. Brains were obtained at autopsy on 10 patients with schizophrenia and 10 age-matched control subjects. Representative Scatchard plots for specific [3H]cAMP bindings to the soluble fraction consisted of a single component with high affinity (Kd = 2.36 nM, Bmax = 737 fmol/mg protein). Among the tested adenyl and guanyl nucleotides, or neuroleptics, cAMP alone potently inhibited the binding (Ki = 4.95 nM). The binding sites for [3H]cAMP were discretely localized, and were in the order of: cerebral cortex = hypothalamus = amygdala > hippocampus = neostriatum = thalamus = nucleus accumbens > globus pallidus = cerebellum. Specific [3H]cAMP bindings to the soluble fractions were about 30% greater in the left temporal cortices of schizophrenic patients, as compared to findings in the right side of the patients and the left side of the control subjects, no control brain showed this asymmetry. The specific [3H]PDBu binding in schizophrenic and control groups did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

[Home intermittent negative pressure ventilation in a case of chronic respiratory failure due to old tuberculous pleuritis]

A 64-year-old male with a history of tuberculous pleuritis at age 29 had received home oxygen therapy since age 58 because of chronic respiratory failure. He was admitted with symptoms of dyspnea at rest and myoclonus at age 62. Because CO2 narcosis occurred twice, we performed intermittent negative pressure ventilation (INPV) after short-term positive pressure ventilation with transnasal intubation. He has received INPV for 7 hours every day at his home for 20 months without acute exacerbation of respiratory failure, and his activity of daily life subsequently improved. In conclusion, INPV seems to be useful for patients with chronic hypercapnic respiratory failure due to lung disease.

Effects of nicorandil on cell proliferation and cholesteryl ester accumulation in arterial smooth muscle cells in culture

Ca2+ regulates a variety of cellular mechanisms in vascular cells as well as in platelets. Nicorandil interacts with the intracellular Ca(2+)-activated processes in vascular smooth muscle cells, while Ca2+ channel blockers such as verapamil and diltiazem block voltage-dependent Ca2+ channels. The effects of nicorandil are due to the hyperpolarization of the membrane, interference with mobilization of Ca2+ from the intracellular storage sites, and blockade of receptor-operated Ca2+ channels. In the present study, the effects of nicorandil on cell proliferation and cholesteryl ester accumulation in rat arterial smooth muscle cells in culture were compared to Ca2+ channel blockers. Smooth muscle cells were prepared from rat thoracic aorta, and the rate of proliferation was determined by measuring the cell number and by [3H]-thymidine incorporation into cellular DNA. The effect of nicorandil on cholesteryl ester content in smooth muscle cells was determined by thin-layer chromatography of the cell extracts. Nicorandil at concentrations of 10(-6) to 10(-4) M, as well as Ca2+ channel blockers (verapamil and diltiazem) inhibited the proliferation and DNA synthesis of cultured smooth muscle cells. The acute inhibitory effects on cell proliferation were observed significantly 16 hours after the addition of the three agents in serum-stimulated cells. These effects were dose dependent, both in acute and in chronic treatment with the three agents. Addition of 10(-5) M nicorandil to medium supplemented with 10% serum resulted in a decrease of the net cholesteryl ester content by 18 +/- 1%, while cellular free cholesterol content was the same as control. Similar results were also obtained in the presence of verapamil and diltiazem.(ABSTRACT TRUNCATED AT 250 WORDS)

[Interaction between vecuronium and pancuronium]

Interaction between vecuronium bromide (VB) and pancuronium bromide (PB) with regard to a change in duration of action was investigated in 32 elective surgical patients divided into four groups. Initial and supplemental drugs were as follow; group I: VB-->VB, group II: PB-->VB, group III: VB-->PB, group IV: PB-->PB. The muscle response was quantified electromyographically. Anesthesia was induced with thiopental. VB or PB 0.08 mg.kg-1 (initial dose) was given to facilitate endotracheal intubation. Anesthesia was maintained with 66% nitrous oxide and 2% sevoflurane in oxygen. Supplemental dose (0.015 mg.kg-1) of the muscle relaxants was administered at 10% recovery of twitch height. Duration of action was defined as the interval between administration and 10% recovery. Duration of action of supplemental doses of VB was significantly longer in group II than in group I. That of PB was significantly shorter in group III than in group IV. Therefore, it should be noticed that duration of action of supplemental relaxant is largely modified by the initial one.

Ca(2+)-dependent stimulatory effect of pituitary adenylate cyclase-activating polypeptide on catecholamine secretion from cultured porcine adrenal medullary chromaffin cells

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates catecholamine secretion from cultured porcine adrenal medullary chromaffin cells in a dose-dependent manner with the half-maximal and maximal doses of 30 nM and 1 microM, respectively. Either removal of extracellular Ca2+ or addition of Gd3+, an inorganic Ca2+ channel blocker, very potently inhibits PACAP-induced catecholamine secretion. Both nicardipine (1 microM) and methoxyverapamil (1 microM), blockers of voltage-dependent Ca2+ channels, are also effective in inhibiting PACAP-induced catecholamine secretion. When the intracellular free Ca2+ concentration ([Ca2+]i) is measured in a fura 2-loaded single chromaffin cell, PACAP is found to cause a sustained increase in [Ca2+]i by mobilizing Ca2+ from both extra- and intracellular pools. It is also found that PACAP stimulates the production of inositol phosphates in a dose-dependent manner, which is not abolished by removal of extracellular Ca2+ unlike the case of nicotine. PACAP increases cAMP content in chromaffin cells in a dose-dependent manner. Removal of extracellular Ca2+ enhances PACAP-induced cAMP production but strongly inhibits PACAP-induced catecholamine secretion. Pretreatment of cells with adenosine-3':5'-monophosphothioate, cyclic, Rp-isomer, a cAMP antagonist, does not block PACAP-induced catecholamine secretion. The addition of forskolin or 3-isobutyl-1-methylxanthine does not enhance the PACAP-induced catecholamine secretion. These results indicate that PACAP activates voltage-dependent Ca2+ channels and phospholipase C as well as adenylate cyclase in cultured porcine adrenal medullary cells and strongly suggest that PACAP-induced catecholamine secretion is mainly mediated by activation of voltage-dependent Ca2+ channels.

Tauroursodeoxycholate and tauro-beta-muricholate exert cytoprotection by reducing intrahepatocyte taurochenodeoxycholate content

Cytoprotection by tauroursodeoxycholic acid and tauro-beta-muricholic acid against taurochenodeoxycholic acid-induced toxicity was examined with reference to intracellular bile acid content in primary cultured rat hepatocytes. In comparison with levels in the group administered taurochenodeoxycholic acid 1 mmol/L alone, lactate dehydrogenase levels in the culture medium decreased significantly in groups simultaneously administered taurochenodeoxycholic acid 1 mmol/L and tauroursodeoxycholic acid 0.5 to 2 mmol/L or tauro-beta-muricholic acid. Results of the trypan blue uptake test indicated that the lactate dehydrogenase release was indeed caused by cell damage. After the administration of tauroursodeoxycholic acid 2 mmol/L or tauro-beta-muricholic acid 2 mmol/L, intracellular taurochenodeoxycholic acid content was consistently reduced to half of that after administration of taurochenodeoxycholic acid alone. Simultaneous administration of dibutyl cyclic AMP also reduced intracellular taurochenodeoxycholic acid content and lactate dehydrogenase release. Being rinsed with tauroursodeoxycholic acid and tauro-beta-muricholic acid after being precultured in taurochenodeoxycholic acid 1 mmol/L also markedly reduced their taurochenodeoxycholic acid content. Taurocholic acid caused limited reduction of intracellular taurochenodeoxycholic acid but not suppression of lactate dehydrogenase release. Taurodehydrocholic acid showed no reduction of taurochenodeoxycholic acid content and no decrease of lactate dehydrogenase release. Although only small amounts of tauroursodeoxycholic acid or tauro-beta-muricholic acid were found to accumulate in hepatocytes, taurocholic acid increased as if replacing taurochenodeoxycholic acid. The results suggest that tauroursodeoxycholic acid or tauro-beta-muricholic acid may exert cytoprotective effects by lowering intracellular taurochenodeoxycholic acid levels associated with their optimal hydrophilicity.

[Extracellular ATP evoked catecholamine release and inositol phosphates formation in cultured porcine adrenal medullary cells]

ATP is ubiquitously present in neural tissues and is released during nerve stimulation. It is known that splanchnic nerve terminals located in adrenal medulla also contain acetylcholine and ATP. These substances may be released concomitantly with nerve stimulation. ATP can exert its effects on neuron-effector junctions by acting directly as a neurotransmitter by increasing or decreasing the release of other neurotransmitters or by modulating their actions. Chern et al. reported that ATP and adenosine inhibited acetylcholine stimulated secretion of catecholamine from isolated bovine adrenal medullary cells. However, Kim et al. showed that extracellular ATP stimulated catecholamine secretion from cultured bovine adrenal medullary cells. Therefore, we investigated the effect of ATP on second messengers levels in cultured porcine adrenal medullary cells as well as catecholamine release from the cells. ATP (500 microM-5mM) evoked catecholamine release significantly (p < 0.05). An unhydrolyzable ATP analogue, ATP gamma S, was several times more potent than ATP in the secretion. ATP-evoked maximal secretion of catecholamine was several times less potent than that evoked by carbachol. Removal of extracellular Ca2+ did not effectively inhibit ATP-induced secretion. 45Ca2+ influx was not observed by the addition of ATP. These results indicated that the catecholamine secretion induced by ATP was independent of extracellular Ca2+. ATP evoked cAMP production slightly at 1mM and did not affect cGMP content. On the other hand, ATP (100 microM-5mM) induced a remarkable increase in inositol trisphosphate, a messenger for mobilization of Ca2+ from intracellular storage sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of a key protein in the mechanism of the excitation-contraction coupling process of frog skeletal muscle, using phenylglyoxal

The excitation-contraction (E-C) coupling process in single twitch fibres from frog toe muscle was inhibited selectively by phenylglyoxal (PGO), a specific guanidyl modifying reagent. A new protein (31.5 kDa), which has PGO-binding ability and seems to play a key role in the E-C coupling process, was solubilized from transverse tubule membrane-junctional sarcoplasmic reticulum complexes (TTM-JSR) of frog skeletal muscles, using 14C-PGO. The monoclonal antibody against this protein applied extracellularly inhibited the E-C coupling process of the single fibres. This protein appears to constitute the very first step of input for E-C coupling. It is considered to behave as an indispensable part of an 'electrometer' to measure membrane potentials. Therefore, the name 'electrometrin' is suggested for the new protein.

A geometrical constraint approach for reproducing the native backbone conformation of a protein

It is known that the backbone conformation of a protein can be reproduced with precision once a correct contact map (two-dimensional representation showing residue pairs in contact) is given as geometrical constraints. There is, however, no way to infer the correct contact map for a protein of unknown structure. We started with one-dimensional constraints using the quantity N14 (the number of neighboring residues within the radius of 14 A). Since the plot of N14 along a chain shows a good correlation with the corresponding amino acid sequence, the N14 profile obtained from the X-ray structure is predictable from the sequence. Construction of backbone conformations under a given N14 profile was carried out in the following two steps: (1) a contact map from the N14 profile was produced by taking the product of N14 values of every two residues; (2) backbone conformations were generated by applying the distance geometry technique to distance constraints given by the contact map. If present, disulfide bonds in a protein, as well as the secondary structure, were treated as additional constraints, and both cases with or without the additional information were examined. The method was tested for 11 proteins of known structure, and the results indicated that the reproduced conformation was fairly good, using an X-ray structure for comparison, for small proteins of less than 80 residues long. The basic assumption and effectiveness of the present method were compared with those of previous studies employing the geometrical constraint approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal myelolipoma: comparison of diagnostic imaging and pathological findings

Myelolipoma of the adrenal gland is a rare, benign, nonfunctioning lesion consisting of fat and bone marrow elements in varying proportions. This tumor is commonly asymptomatic and usually discovered during various diagnostic imaging examinations performed for unrelated diseases. If a primary malignant or metastatic adrenal tumor cannot be excluded, ultrasound- or computed tomography-guided needle biopsy of the tumor is necessary. We report a case of adrenal myelolipoma associated with advanced gastric carcinoma and compare the diagnostic imaging findings with the pathological findings of the adrenal myelolipoma.

[Advances in diagnostic procedures for detection of pheochromocytoma]

Pheochromocytoma arises from chromaffin tissue, usually in the adrenal medulla, and is a cause of curable hypertension. In most cases, clinical acumen alone is not sufficient to diagnose pheochromocytoma. Therefore, the diagnosis of this disorder has become almost totally dependent on laboratory test results. The most widely used biochemical procedures for detection of pheochromocytoma are measurements of urinary catecholamines or their metabolites, such as vanillylmandelic acid (VMA) or total metanephrine (MN). Traditional spectrophotometric and fluorometric methods for urinary catecholamines and their metabolites are being replaced by highly sensitive and selective chromatographic methods. Plasma noradrenaline and adrenaline measurements are of additional diagnostic value in determining recent catecholamine release and response to clonidine suppression. For either urine or plasma measurements, appropriate patient preparation, sample collection and method validation along with an understanding of the variable pattern of catecholamine secretion and metabolism in pheochromocytoma are essential. Localization of tumors is important for the surgeon and is accomplished by CT scan, 131I-metaiodobenzylguanidine scintiscans or abdominal aortography.

Microtubule-independent choleresis and anti-cholestatic action of tauroursodeoxycholate in colchicine-treated rat liver

In order to cast light on the anti-cholestatic and cytoprotective properties of ursodeoxycholic acid (UDCA), intrahepatic transport and secretion of bile salts and biliary phospholipids were investigated by using isolated perfused livers from colchicine-pretreated rats. Administration of taurocholic acid (TCA) after colchicine pretreatment induced marked cholestasis. Tauroursodeoxycholic acid (TUDCA) treatment, in contrast, was associated with maintenance of bile flow, with excretion rates of bile acids and phospholipids similar to those in control animals. Furthermore, TCA-induced cholestasis in colchicine-treated rat livers was clearly decreased by co-administration of TUDCA. Although simultaneous addition of UDCA also showed slight improvement, with or without taurine pre-treatment, biliary bile-salt analysis also showed that cholestasis was markedly remitted as the excretion of taurine-conjugated UDCA was increased. The results suggest that the cytoprotective and anti-cholestatic effects of TUDCA may be linked to action at the intrahepatocyte level, represented by mild detergent effects on organelle lipids and preservation of intracellular transport even under microtubule-dysfunctional conditions. In addition, it was indicated that cytoprotective effects of UDCA may also be exerted after its conjugation with taurine inside hepatocytes.