Control of gallbladder contractions by cholecystokinin through cholecystokinin-A receptors in the vagal pathway and gallbladder in the dog

The mechanism of CCK action on gallbladder contractions in the physiological condition is unclear. Gallbladder contractions were monitored by means of chronically implanted force transducers in conscious dogs. Postprandial gallbladder contractions were partially inhibited by atropine and hexamethonium, and completely inhibited by devazepide. In vitro contractile response of canine gallbladder muscle strips to CCK-8 was also studied. CCK-8-induced muscle strip contraction was atropine and tetrodotoxin resistant, but was completely eliminated by devazepide. The existence of CCK receptors in the vagal nerve and gallbladder was examined by means of autoradiography. Forty-eight hours after ligation of the abdominal vagus, CCK-8 binding sites were found to accumulate in the subdiaphragmatic vagal nerve immediately proximal to the ligature, and similar binding sites were also found in the gallbladder smooth muscle layer. These binding sites were displaced by the addition of 10(-7) mol/1 unlabeled CCK-8 and devazepide, but L-365,260 had no effect. In conclusion, it is considerable that postprandial CCK-induced gallbladder contractions are controlled through CCK-A receptors both on the vagal nerve in stimulating endogenous release of acetylcholine and on the gallbladder directly to stimulate muscle contraction in the dog.

Elucidation of nucleus-cytoplasm interaction: change in ability of the nucleus to express sexuality according to clonal age in Paramecium

The expression of sexual activity in Paramecium caudatum is repressed for about 50 fissions after conjugation. The ability of the macronucleus to affect the expression of sexual activity according to the age of clonal development was investigated using the macronuclear fusion-reorganization method. When a mature macronucleus was transplanted into an immature cell and fused with a macronucleus in the immature cell, the clones derived from the recipient showed sexual immaturity. In a reverse experiment, an immature macronucleus was transplanted into a mature cell, and the clones also showed sexual immaturity. The ability of the macronucleus to transform mature cells to immature cells was clonal age-dependent. The characteristics of the immature-mature hybrid macronucleus indicate that the immature macronucleus is dominant over the mature macronucleus with respect to the ability to express sexual activity. On the other hand, in cells of the early immaturity period, the micronucleus, known as the germ nucleus, shows the ability to undergo meiosis and eventually to produce progeny under control of the mature macronucleus. The expression of sexual activity is thought to be governed by the clonal age of the macronucleus and not by the clonal age of the micronucleus or cytoplasm. The macronucleus seems to determine the ability to express sexual activity by counting post-conjugation divisions and keeping track of the age of the clone.

Stimulatory mechanism of EM523-induced contractions in postprandial stomach of conscious dogs

BACKGROUND & AIMS

EM523, a motilin agonist, is intended to be used as a gastroprokinetic during the postprandial period, but the mechanism(s) by which EM523 stimulates postprandial contractions in the stomach has not been studied before. The aim of this study was to examine the mechanism of contraction-stimulating activity by EM523 in fed dogs.

METHODS

Contractile activity in the gastric antrum of 5 dogs was monitored using a long-term implanted force transducer and measured by integrating the area under the curve. Test materials were continuously infused or injected intravenously.

RESULTS

EM523 (1-30 micrograms/kg) induced a dose-dependent increase in fed-type contractions. EM523-induced contractile activity was partially inhibited by atropine, hexamethonium, dopamine, 5-hydroxytryptamine 3 (5-HT3) receptor antagonist, and substance P antagonist. Atropine-resistant and EM523-induced contractions were further inhibited by 5-HT3 receptor antagonist and substance P antagonist, and the combined use of the two antagonists completely eliminated the atropine-resistant and EM523-induced contractions.

CONCLUSIONS

EM523-induced contractions in the fed stomach are quite different from phase III contractions in the fasted state and are mediated partially through the cholinergic pathway. The noncholinergic pathway involves 5-HT3 and neurokinin 1 receptors.

[A case of localized fibrous tumor of the pleura with bloody pleural effusion]

A 25-year-old female came to our hospital with the chief complaint of right dorsal pain. On her initial chest X-ray, the tumor (5 x 3 cm) was recognized in the right lower lung field. The tumor grew rapidly during the three month period between the initial X-ray taken on her first visit and her getting admitted in the hospital. A preoperative diagnosis was done by percutaneous aspiration biopsy. Initial diagnosis of spindle cell tumor was made. Partial resection of right lower lobe with chest wall resection was carried out. There were about 500 ml of bloody pleural effusion. Macroscopically, the tumor was encapsulated, measuring 8.0 x 6.0 x 5.0 cm. The cross section was of a yellowish brown solid tumor. The histological diagnosis was of a low grade malignant fibrous mesothelioma. Only 14 cases of localized mesothelioma with pleural effusion including our case have been reported in Japan. She is still alive nine months after surgery. This patient should be carefully followed for the recurrence of the disease.

Kinetics and mechanism of photocycloaddition of deoxyuridines to 2,3-dimethyl-2-butene

The mechanism of photocycloaddition of 2'-deoxyuridine (1a) and thymidine (1b) to 2,3-dimethyl-2-butene (Bu) in acetonitrile by UV irradiation has been studied. The reciprocal quantum yield for the cycloaddition increased linearly with reciprocal concentrations of Bu in acetonitrile to give limiting quantum yields at infinite concentration of Bu as 0.030 and 0.0096 for 1a and 1b, respectively. This shows that the cycloaddition proceeds in a two-step mechanism between the triplet state of 1 and Bu through biradical intermediates. Addition of cis-1,3-pentadiene quenched the reaction obeying the Stern-Volmer equation. The above quenching experiments and laser transient spectroscopy revealed that the triplet state of 1a reacts with Bu with much larger rate constant (1.3-1.6 x 10(9) M-1 s-1) than that of 1b (4-5 x 10(7) M-1 s-1) reflecting larger steric hindrance exerted in the reaction of 1b than that of 1a.

Distribution of enteric neural peptide YY in the dog gastrointestinal tract

Various regions of the dog gastrointestinal tract were investigated for the distribution of peptide YY (PYY) neurons using immunocytochemistry and radioimmunoassay. PYY neurons that encircled non-PYY-immunoreactive neurons were mainly observed in the myenteric plexus from the stomach to the colon. There was more PYY-like immunoreactivity in the muscle layer of the stomach and ileum than in the other intestines. The results of high performance liquid chromatography revealed that neural PYY-immunoreactive substance is identical to authentic PYY. PYY was not localized in the cholinergic neurons. These results indicate that PYY, as a neuropeptide, is involved in the regulation of gastrointestinal function.

Inhibition of motilin-induced phase III contractions by pentagastrin in Heidenhain pouch dogs

We compared the inhibitory effects of histamine and pentagastrin (PG) on motilin-induced upper gastrointestinal phase III activity in conscious dogs that had surgically prepared Heidenhain pouchs (HP). Contractile activity was measured by means of chronically implanted force transducers, and changes in pH of the perfusate through the HP were monitored simultaneously. Intravenous infusion of PG (4 micrograms/kg-hr) inhibited motilin-induced phase III activity both in the main stomach and in the HP, whereas histamine (40 micrograms/kg-hr) inhibited activity only in the main stomach. Famotidine (0.3 mg/kg, i.v., the dose that completely inhibited gastric acid secretion by PG or histamine) blocked the inhibition of phase III activity induced by histamine but did not affect PG-induced inhibition. L-364,718 (1 mg/kg, i.v.), which had no effect on the PG-induced decrease in the pH of the perfusate lowered by PG, reversed the inhibition of phase III activity by PG in the HP but not in the main stomach. However, L-364,718, when combined with famotidine, potently reversed the PG-induced inhibition of phase III activity both in the main stomach and in the HP. These results show that the inhibitory effect of PG on motilin-induced phase III activity is brought about by two distinctive mechanisms, gastric acid and the cholecystokinin receptors-dependent mechanism, whereas the histamine-induced inhibition is mediated only by gastric acid. In the vagally denervated HP, however, gastric acid is not involved in an inhibitory effect of PG.

Pathologic dislocation of the hip in von Recklinghausen's disease: a report of two cases

We report two cases of von Recklinghausen's disease in which hip dislocations occurred gradually without trauma. In one case, the right hip joint dislocated at the age of 8 years, and in another case, the left hip dislocated at 2 years and the right hip at 3 years. Each case was accompanied by bone changes around the affected hips, vertebral deformity, and spinal tumor. One case had hemihypertrophy of the involved lower extremity. Both structural changes around the hip joint and paralysis may have resulted in the hip dislocation.

Vagovagal inhibition of motilin-induced phase III contractions by antral acidification in dog stomach

Gastric acidification at pH 1.0 strongly inhibits the spontaneously occurring and motilin-induced phase III contractions in canine and human stomach. In this study, we examined inhibition by gastric acidification in dogs following gastrojejunostomy, truncal vagotomy, and antrectomy. As a result, gastric acidification with 0.1 N HCl solution at pH 1.0 for 30 min at a rate of 1.0 ml/min significantly inhibited motilin-induced phase III activity to 23.5 +/- 5.9% of the control in the normal intact dogs and to 17.2 +/- 3.4% in the gastrojejunostomized dogs. In the antrectomized dogs, gastric acidification did not significantly inhibit the action of motilin (81.7 +/- 10%), but, in the vagotomized dogs, gastric acidification inhibited the action of motilin to 72.0 +/- 4.9%; the inhibition was much weaker than in the intact and gastrojejunostomized dogs but was significant. The duodenal acidification had no effect at all on the action of motilin (94.6 +/- 12.5%) in the gastrojejunostomized dogs. These findings strongly suggest the existence of a vagovagal reflex in the inhibition of motilin-induced phase III contractions by gastric antral acidification, although the involvement of sympathetic regulation cannot be completely ruled out.

Inhibition of phase III activity by acid in canine stomach

Very few phase III activity of the interdigestive migrating contractions (phase III) occurs in the stomach of fasted duodenal ulcer patients. But the mechanism is not well understood. In this study, we studied the effect of gastric and duodenal acidification on the spontaneous phase III activity in the upper gastrointestinal tract of conscious dogs. Gastric and duodenal motor activity in 5 conscious dogs was monitored by means of chronically implanted force transducers. Intragastric pH changes were measured by placing a pH glass electrode in the gastric antrum. Intragastric and intraduodenal acidification was achieved by i.v. infusion of histamine, and by intragastric and intraduodenal instillation of acidic solutions of different pHs. The plasma motilin concentrations were measured by radioimmunoassay. Histamine (40 micrograms/kg/h) inhibited spontaneous phase III activity, but the histamine-induced inhibition was completely prevented by pretreatment with famotidine, a potent histamine H2 receptor antagonist (0.3 mg/kg, i.v.). Intragastric acidification at pH 1.0 strongly inhibited spontaneous phase III activity, but an acidic solution at pH 2.0 had no effect in inhibiting phase III activity. Intraduodenal acidification at pH 1.0 also inhibited spontaneous phase III activity. Histamine injection and gastric and duodenal acidification at pH 1.0 strongly suppressed motilin release. It is concluded that gastric and duodenal acidification at pH 1.0 inhibits the occurrence of the spontaneous phase III activity, and the suppression of endogenous release of motilin due to gastric and duodenal acidification at pH 1.0 is involved in this inhibitory mechanism.

Inhibition of phase III activity by acidifying stomach in vagally denervated and innervated dogs with gastric pouches

BACKGROUND/AIMS

Intragastric acidification at pH 1.0 strongly inhibits phase III contractions in the dog, but this mechanism is not well known. We studied the mechanism in conscious dogs.

METHODS

Vagally denervated and innervated gastric pouch dogs were prepared. Force transducers were chronically implanted on the serosa of the pouch, main stomach, and mid-duodenum. The pH of the perfusate was monitored.

RESULTS

Administration of histamine (40 micrograms.kg-1.h-1 intravenously [i.v.]) and instillation of acidic saline at pH 1.0, but not pH 2.0, into the main stomach strongly inhibited the motilin-induced (0.1 microgram/kg i.v.) phase III activity in the main stomach and the innervated pouch but did not influence contractions in the extrinsically denervated pouch. Famotidine completely reversed the histamine-induced inhibition of phase III in the main stomach and Pavlov pouch. Acidification of the pouch itself or duodenum at pH 1.0 did not affect contractions in the main stomach and pouch of either type.

CONCLUSIONS

The mechanism of inhibition of motilin-induced phase III activity by acid in the stomach involves the intact vagovagal reflex, but sympathetic participation is not completely ruled out. The inhibition of motilin-induced phase III activity may originate in the antral mucosa of the stomach.

A novel class of platelet activating factor (PAF) antagonists. II. Modification of the 2-position of the glycerol backbone of PAF-sulfonamide isosteres

In a continuing effort to obtain more potent platelet activating factor (PAF) antagonists, we tried to synthesize a series of PAF-sulfonamide isosteres in which the substituent at the 2-position was modified to an acetoxy equivalent other than the methoxy group. These modifications produced highly active PAF antagonists. Compound 3-[2-(5-methyl-2H-tetrazol-2-yl)-3-(octadecylcarbamoyloxy) propylaminosulfonyl]propylquinolinium iodide (52) showed the most potent activity in the in vitro inhibitory effect on PAF-induced platelet aggregation in rabbit platelet-rich plasma (IC50 = 125 nM) and also in the in vivo protective effect on PAF-induced lethality in mice, with prolonged duration of action. Optically active enantiomers of this compound were synthesized and the (S)-(-)-isomer (IC50 = 87 nM) was found to be three times more potent that the (R)-(+)-isomer (IC50 = 289 nM), clearly exemplifying the enantioselectivity in the PAF-antagonist action of this novel compound.

A novel class of platelet activating factor (PAF) antagonists. I. Synthesis and structure-activity studies on PAF-sulfonamide isosteres

New platelet activating factor (PAF) antagonists, 3 were synthesized by replacing the charged phosphate and trimethylammonium moieties with sulfonamide and heterocyclic quaternary ammonium functionalities, respectively (PAF-sulfonamide isosteres). Darmstoff phosphatidic acid analogues of this class (Darmstoff-sulfonamide isosteres), 6 were also synthesized. The activity of these compounds as PAF antagonists was evaluated from their in vitro inhibitory effect on PAF-induced platelet aggregation in rabbit platelet-rich plasma. Among the compounds tested, some of the 2-methoxypropane derivatives with an octadecylcarbamoyloxy or octadecylcarbamoylthio side chain at the 1-position and a propylsulfonamide function bearing a terminal polar substituent such as a quaternary quinolinium or substituted quinolinium group at the 3-position were found to be the most potent (IC50 = 0.3-0.6 microM).

Synthesis of thromboxane receptor antagonists with bicyclo[3.1.0]hexane ring systems

Thromboxane A2 receptor antagonists 11a, 15a, 26a, 30a, 34a, 36a, 46a, 52a, 61a, 72a, and 82a, which contain 6-oxabicyclo[3.1.0]hexane, 6-thiabicyclo[3.1.0]hexane, bicyclo[3.1.0]hexane, or 6,6-dimethylbicyclo[3.1.0]hexane ring systems with heptenoic and (phenylsulfonyl)amino side chains, and their corresponding sodium salts and methyl esters were synthesized. This study then examined the inhibitory effects of their sodium salts for the platelet aggregation induced by arachidonic acid with rabbit platelet-rich plasma and platelet aggregation induced by collagen with rat washed platelets.

Aldosterone antagonists. 2. Synthesis and biological activities of 11,12-dehydropregnane derivatives

Several steroid derivatives having the delta 11-pregnane skeleton with a 17-gamma-spirolactone function were synthesized to evaluate their antialdosterone activity and to elucidate the relation between their binding affinity to mineralocorticoid receptor (MR) and their mineralo- and/or antimineralocorticoid activity. Although many of the synthesized compounds showed strong binding affinity for the MR and aldosterone agonist activity, 3-(17 beta-hydroxy-3-oxoandrosta-1,4,6,11-tetraen-17 alpha-yl)propionic acid gamma-lactone exhibited good aldosterone antagonist activity in an in vivo assay. Its in vivo antiandrogenic activity was also found to be relatively weak.

Relationships of the molecular structure of aldosterone derivatives with their binding affinity for mineralocorticoid receptor

The molecular structures of 19-nor-11-deoxycorticosterone (III) and 21-hydroxypregna-4,11-diene-3,20-dione (IV) were determined by X-ray crystallographic analysis and the factors affecting the binding affinities for the mineralocorticoid receptor were examined with six aldosterone derivatives (I-VI) containing these two compounds. The most important factor was found to be the steric one; affinity increased with increasing flatness of the structure. The electronic factor may be a minor influence although a good relationship was found between the affinity and the 13C-NMR chemical shift of the C(5) atom. The factor playing no role in the binding is the hydrophobic one.

Microinjection of immaturin rejuvenates sexual activity of old Paramecium

The sexual activity of aged Paramecium that underwent about 700 fissions after conjugation was remarkably decreased. Microinjection of a soluble cytoplasmic fraction prepared from young immature cells (about 20 fissions after conjugation) restored the sexual activity of the aged cells to that of presenescent mature cells. The factor responsible for the recovery of the sexual activity was shown to have the same characteristics as immaturin in terms of molecular size and net charge. Rejuvenation of sexual activity lasted up to 20 fissions after microinjection. However, cell division rate or fertility after self-conjugation was not increased by the microinjection. Our finding indicates that the decrease in sexual activity caused by aging was not due to defects in the genes for mating substances but to a decrease in the activity of a soluble protein responsible for the expression of mating activity. This is the first description of the restoration of a senescent defect by microinjection of young cytoplasmic components into Paramecium.

Effect of dilazep on decrease in myocardial pH during ischemia in dogs

The present study was undertaken in order to examine whether dilazep (1,4-bis-[3-(3,4,5-trimethoxybenzoyloxy)propyl]perhydro-1, 4-diazepine dihydrochloride monohydrate) attenuates myocardial acidosis induced by coronary artery occlusion in dogs. In dogs with nonischemic normal heart, dilazep (300 or 500 micrograms/kg i.v.) increased blood flow in the left anterior descending coronary artery (LAD) with a decrease in heart rate and diastolic blood pressure. In other dogs, LAD flow was reduced by an occluder by 57 to 68% (partial occlusion) for 90 min. Partial occlusion for 30 min decreased myocardial pH by 0.67 to 0.87 pH units, increased ST segment of the surface electrocardiogram, and decreased regional myocardial contractile force. Dilazep was injected i.v. 30 min after partial occlusion. The decrease in myocardial pH induced by partial occlusion was attenuated by the injection of 300 micrograms/kg of dilazep insignificantly and by that of 500 micrograms/kg of dilazep significantly. Restoration of myocardial [H+] induced by dilazep was calculated from the myocardial pH data. Dilazep (500 micrograms/kg) restored myocardial [H+] induced by partial occlusion by 56.7%, and saline solution restored it by 27.4% 60 min after the drug injection, the actual restoration induced by dilazep being 29.3%. Dilazep, however, did not restore the ST segment elevation and contractile force decrease. It is concluded that dilazep attenuates myocardial acidosis during ischemia.

Attenuation by isosorbide dinitrate of coronary occlusion-induced acidosis in the dog myocardium

In dogs anaesthetized with pentobarbitone, the thorax was opened and myocardial pH measured continuously by the use of a glass pH electrode inserted in the left ventricular wall. The left anterior descending coronary artery (LAD) was partially occluded so that the LAD flow could be reduced to a half or one-third of the original flow (partial occlusion). LAD partial occlusion was continued for 90 min, drug or saline being infused for the last 60 min of this period. LAD occlusion decreased myocardial pH significantly by 0.41 to 0.67 pH units, and increased ST segment of the surface electrocardiogram from 11.7 to 12.1 mV. In dogs with non-ischaemic normal hearts, isosorbide dinitrate (ISDN; 1 mg kg-1) did not change markedly either the LAD flow, myocardial pH or heart rate, whereas it decreased myocardial contractile force (determined by a strain gauge arch) slightly and both the systolic and diastolic blood pressure markedly. In dogs with partial LAD occlusion, ISDN (1 mg kg-1) increased myocardial pH significantly and decreased blood pressure, but did not change ST segment elevation in an epicardial lead. These results indicate that ISDN attenuates ischaemia-induced acidosis without attenuating ischaemia-induced ST elevation in the dog myocardium.

Effect of cinpropazide on ischemic myocardial acidosis in dogs

In dogs anesthetized with pentobarbital, the left anterior descending coronary artery (LAD) was occluded by an occluder so that the LAD flow could be set to about half the original flow (partial occlusion). Partial occlusion of the LAD continued for 90 min, and myocardial pH decreased by 0.71 pH unit 30 min after the start of partial occlusion. Cinpropazide, a coronary vasodilator, was injected intravenously 30 min after partial occlusion. Cinpropazide at the dose of 1 mg/kg, which increased LAD flow insignificantly in the nonischemic normal heart, attenuated the myocardial pH that has been reduced by partial occlusion, with a slight reduction in diastolic blood pressure. Restoration of myocardial [H+] 60 min after the injection of cinpropazide was 75.3%, and that of saline solution was 29.5%, indicating that cinpropazide restored the myocardial [H+] by 45.8% during ischemia. The effect of cinpropazide to increase myocardial pH was not observed in the dog with nonischemic heart, however. It is concluded that cinpropazide attenuates myocardial acidosis during ischemia.

A gamma ray-induced non-excitable membrane mutant in Paramecium caudatum: a behavioral and genetic analysis

A new CNR (caudatumnon-reversal) mutant ofParamecium caudatumwas isolated after gamma ray mutagenesis. This CNR lacks not only the transient inward Ca2+current but also the sustained Ca2+current. It was shown to complement the three known CNR mutants ofP. caudatum(cnrA, cnrBandcnrC) by crossbreeding analyses. Thus, this new mutant belongs to a 4th CNR locus, designatedcnrD. The defect ofcnrDcan be partially rescued by microinjection of cytoplasm from any of the three CNR mutants or the three Pawns (pwA, pwBandpwC) inP. tetraurelia. Since the three CNR genes have been shown to be different from the three Pawn genes by cytoplasmic complementation test (Hagaet al.1983), this result suggests thatcnrDis the 7th non-excitable mutant inParamecium. Thus, there are at least seven genes controlling Ca2+channel function inParamecium.

Aldosterone antagonists. 1. Synthesis and biological activities of 11 beta,18-epoxypregnane derivatives

Several steroid derivatives having the 11 beta,18-epoxypregnane skeleton, 7, 8, 19, 20, 21, and 31, were synthesized to evaluate their antialdosterone activity. Among them, 3-(9 alpha-fluoro-17 beta-hydroxy-3-oxoandrost-4-en-17 alpha-yl)propionic acid gamma-lactone (31) possessed fairly strong binding affinity for the cytoplasmic mineralocorticoid receptor of rat kidney and exhibited good aldosterone antagonist activity in an in vivo assay. However, its agonistic nature cannot be ignored. The properties of 31 as an aldosterone antagonist were enhanced by its very low to negligible binding affinity for the androgen, progestin, estrogen, and glucocorticoid receptors.

Effect of NCO-700, an inhibitor of protease, on myocardial pH decreased by coronary occlusion in dogs

During myocardial ischemia in dogs effects of NCO-700, a protease inhibitor on myocardial pH, were investigated. Ischemia was produced for 90 min by partial occlusion of the left anterior descending coronary artery (LAD). Myocardial pH was measured by a micro glass pH electrode inserted in the subendocardium of the LAD area. Before partial occlusion, myocardial pH was 7.50-7.67. It decreased by 0.65 to 0.86 pH units after partial occlusion. NCO-700 was injected intravenously after 30 min partial occlusion. At a dose of 5 or 20 mg/kg NCO-700 increased myocardial pH, which had been decreased by LAD partial occlusion, by 0.26 or 0.31 pH units, respectively. In the nonischemic myocardium pH increased only 0.03 units. Drug-induced restoration of myocardial [H+] was then calculated. At a dose of 5 or 20 mg/kg NCO-700 restored myocardial [H+], which had been increased by partial occlusion. However, NCO-700 did not attenuate the ischemia-induced elevation of ST segment of the surface electrocardiogram. These observations demonstrate that NCO-700 attenuates myocardial pH depressed by partial occlusion of LAD.

Characterization and purification of a soluble protein controlling Ca-channel activity in paramecium

The analysis of the voltage-sensitive Ca++ channel of the unicellular eucaryote, Paramecium has been extended to a biochemical level based on recent observations that the transfer of cytoplasm from wild-type cells into mutants lacking Ca++-channel function ("pawn" in P. tetraurelia and "CNR" in P. caudatum) causes mutant cells to regain Ca++-channel function. We have microinjected various cytoplasmic fractions into mutant cells and measured the restored Ca++-channel function using a convenient behavioral assay. Following the "curing" activity, we characterized and purified the component from wild-type cytoplasm that can restore the function missing in cells carrying mutations in the cnrC gene. The curing factor is not an RNA, but a heat-labile, -SH-containing protein that appears to affect existing mutant channels on the ciliary membrane. We have purified this factor over 500-fold from the soluble cytoplasm using conventional techniques. The protein is of low apparent molecular weight (less than 30,000 daltons), acidic, soluble, and does not have the properties of calmodulin.

Characterization of cytoplasmic factors which complement Ca2+ channel mutations in Paramecium tetraurelia

The analysis of Ca2+-channel function in the single-celled eukaryote Paramecium can be extended to a biochemical based on recent observations that transfer of cytoplasm from wild-type cells into mutants lacking Ca2+-channel function ("pawn" mutants) causes the mutant cells to regain Ca2-channel activity. Using a convenient behavioral assay for Ca2+-channel function, we have used microinjection of cytoplasmic fractions into mutant cells to enrich for and characterize those components from wild-type cytoplasm which can "cure" cells carrying mutations in the 3 different pawn genes affecting Ca2+-channel activity (pwA,pwB, and pwC). In each case, the curing factor appears to be a protein component of an intracellular membrane. They are distinguishable on the basis of thermal, pH and divalent ion sensitivities. In addition, the factor curing the pwC mutational defect has been purified more than 180-fold. Furthermore, the pwB curing activity appears to be amplified during sequential transfer between pwB cells.

Is ischemia-induced pH decrease of dog myocardium respiratory or metabolic acidosis?

Ischemia causes myocardial acidosis and elevation of myocardial CO2 tension (PCO2). We performed the present study to examine whether accumulation of hydrogen ion is a cause or result of accumulation of CO2. The myocardial pH and PCO2 were measured simultaneously in the dog heart, and the concentration of HCO-3 [( HCO-3]) was calculated according to the Henderson-Hasselbalch equation. Ischemia was induced by either partial or complete occlusion of the left anterior descending coronary artery (LAD). After LAD occlusion, the myocardial pH decreased with a marked decrease in [HCO-3], indicating that metabolic acidosis occurred. We ascertained in experiments with blood sample in vitro that an addition of lactic acid into blood decreased both [HCO-3] and pH (metabolic acidosis), whereas an addition of CO2 gas into blood increased [HCO-3] and decreased pH (respiratory acidosis). These findings suggest that ischemic acidosis is not respiratory in nature, but metabolic. The myocardial pH decrease due to ischemia, however, cannot be explained by the tissue lactate accumulation alone, because the decrease of [HCO-3] is far greater than the increase of lactic acid during ischemia.

Ultrastructural localization of hCG in the placenta and in testicular germ cell tumors

Human chorionic gonadotrophin(hCG)-producing cells in the human placenta and in testicular germ cell tumors have been investigated by ultrastructural immunohistochemistry using labeled Fab'fragments of anti-hCG-alpha and anti-hCG-beta. Most reaction products were demonstrated in the rough endoplasmic reticulum (rER) and perinuclear spaces of syncytiotrophoblastic giant cells ( STGC ) occurring in embryonal carcinomas and in syncytial cells observed in choriocarcinomas and in normal placenta. The rER of placental and choriocarcinomatous syncytial cells was highly developed and invariably showed a positive reaction. However, the rER of STGCs varied both with regard to its degree of development and its immunoreactivity with hCG. Localization of hCG in the Golgi apparatus and in cytoplasmic granules was indefinite. Mononuclear cells reacting positively with anti-hCG-alpha or -beta were also demonstrated. Cytotrophoblast-like cells which failed to react with anti-hCG-alpha or -beta were noted adjacent to sTGCs and the significance of these cells is discussed.

Intra- and interspecific complementation of membrane-inexcitable mutants of Paramecium

Membrane excitation was the basis for backward swimming of Paramecium facing stimulus. According to standard genetic tests, inexcitable mutants fell into three complementation groups for both Paramecium tetraurelia (pwA, pwB, and pwC) and Paramecium caudatum (cnrA, cnrB, and cnrC). Cytoplasm from a wild type transferred to a mutant through microinjection restored the excitability. Transfusions between genetically defined complementation groups of the same species effected curing, whereas transfusions between different mutants (alleles) of the same group or between sister cells of the same mutant clone did not. Cytoplasmic transfers of all combinations among the six groups of mutants of the two species showed that any cytoplasm, except those from the same group, was able to cure. Since the pawns and the caudatum nonreversals complement one another through transfusion, they appeared to belong to six different complementation groups. The extent of curing, the amount of transfer needed to cure, and the time course of curing were characteristic of the group that received the transfusion. Variations in these parameters further suggested that the six groups represented six different genes. Because the donor cytoplasms from either species were equally effective quantitatively in curing a given mutant, the curing factors were not species specific. These factors are discussed.

Microinjection of cytoplasm as a test of complementation in Paramecium

Mutants in Paramecium tetraurelia, unable to generate action potentials, have been isolated as cells which show no backward swimming in response to ionic stimulation. These "pawn" mutants belong to at least three complementation groups designated pwA, pwB, and pwC. We have found that microinjection of cytoplasm from a wild-type donor into a pawn recipient of any of the three complementation groups restores the ability of the pawn to generate action potentials and hence swim backward. In addition, the cytoplasm from a pawn cannot restore a recipient of the same complementation group, but that from a pawn of a different group can. Electrophysiological analysis had demonstrated that the restoration of backward swimming is not due to a simple addition of ions but represents a profound change in the excitable membrane of the recipient pawn cells. Using known pawn mutants and those which had previously been unclassified, we have been able to establish a perfect concordance of genetic complementation and complementation by cytoplasmic transfer through microinjection. This method has been used to classify pawn mutants that are sterile or hard-to-mate and to examine the ability of cytoplasms from different species of ciliated protozoa to restore the ability to swim backward in the pawn mutants of P. tetraurelia. A cell homogenate has also been fractionated by centrifugation to further purify the active components. These results demonstrate that transfer of cytoplasm between cells by microinjection can be a valid and systematic method to classify mutants. This test is simpler to perform than the genetic complementation test and can be used under favorable conditions in mutants that are sterile and in cells of different species.

A protein called immaturin controlling sexual immaturity in Paramecium

As in many metazoans, clones of some species of Paramecium have, after conjugation, a period of immaturity during which the cells cannot mate. The duration of immaturity is measured by the number of cell generations, which remains fairly constant, although duration in time varies with rate of cell reproduction. Genic involvement is shown by mutants with reduced periods of immaturity. In three different groups of Paramecium species, the cytoplasm of immature cells apparently contains the same substance which represses mating activity when injected into sexually mature cells. The immaturity-inducing substance seems to be absent from sexually mature cells, as brei made not only from mature cells in the stationary phase (mating-reactive cells), but also from those in the log phase (mating-non-reactive cells), does not repress mating activity when injected into mature cells. Variations in the amount of the substance during immaturity suggest that it controls the duration of the period. We have isolated and partially characterized the substance-a single protein called immaturin. The activity of immaturin is dose dependent and associated with a heat-labile protein of molecular weight (MW) 10,000.

Restoration of membrane excitability in a behavioral mutant of Paramecium caudatum during conjugation and by microinjection of wild-type cytoplasm

When cells of the behavioral mutant cnrC of Paramecium caudatum were mated with the wild type, phenotype change from CNR (no backward swinning) to wild type in the cnrC mate occurred immediately after the formation of tight pairs. No change of phenotype occurred when cells of cnrA or cnrB were mated with wild type. Phenotypic change from CNR to wild type in cells of cnrC was also induced by microinjection of wild-type cytoplasm. Microinjection of wild-type cytoplasm induced no change in cells of cnrA or cnrB. Phenotypic change in the cnrC mate during conjugation can be explained by cytoplasmic exchange during conjugation, though transfer of membrane sites for excitability through membrane fluidity cannot be ruled out.