[Studies on the combination action of ampicillin and dicloxacillin (author's transl]

The combination action of ampicillin and dicloxacillin was studied in vitro. The following conclusions were obtained. 1) When both ampicillin and dicloxacillin were employed, an increase in antibacterial activity was observed against beta-lactamase producing E. coli No. 106 (clinical isolated strain). 2) A synergistic action of ampicillin and dicloxacillin was proved by chequer board dilution method for E. coli No. 106. 3) A same synergistic action of ampicillin and dicloxacillin was also proved by the growth curve for E. coli No. 106. 4) Dicloxacillin showed an inhibition in degradation of ampicillin brought about by beta-lactamase extracted from E. coli No. 106. 5) When the organisms of E. coli No. 106 were exposed to the combination of ampicillin and dicloxacillin, spheroplast-like structure and lysis were observed by scanning electron microscope.

Mechanism of supraventricular parasystole

Two patients with supraventricular parasystole (one atrioventricular and one auricular) are reported. In both patients, reentrant extrasystoles appeared to occur as the result of Mobitz type I second-degree entrance block. We believe that when a sinus impulse fell soon after the absolute refractory period of the pathway containing the parasytolic focus, it reached and discharged the focus after marked delay, and thereafter became a reentrant extrasystole. In interectopic intervals containing more than one sinus beat, the number of intervening sinus beats was always even, suggesting the presence of concealed reentrant extrasystolic bigeminy. The observations in the present report and in our previous patients with ventricular parasystole strongly suggest that most cases of parasystole, whether ventricular or supraventricular, or whether intermittent or "continuous," may be governed by second-degree entrance block.

NAD- and FAD-3'-pyrophosphates--enzymic synthesis and inertness

Computed tomography of the brain was performed as part of the initial staging evaluation of 84 patients with small cell lung cancer. Brain scans indicative of metastatic disease were obtained in 12 (14%) patients, two of whom had no neurologic signs or symptoms. One of these had no other extrathoracic disease. Brain scans without evidence of metastatic disease were obtained in 72 patients, 58 (80.5%) of whom had no signs or symptoms suggestive of metastatic intracranial disease. In the 14 patients with neurologic symptoms but negative computed tomographic scans, other explanations than brain metastases were found. It was concluded that head scanning is a sensitive and accurate method of detecting central nervous system metastases in patients with small cell lung cancer. However, head computed tomography should not be included as part of the initial staging evaluation of the neurologically asymptomatic patients. In only one of 60 such patients did the brain scan change the initial clinical staging, which included chest films, liver and bone scans, and bone marrow biopsy.

Changes in pattern of breathing following baroreceptor stimulation in cats

The effects of baroreceptor stimulation produced by a sudden rise in arterial pressure on respiratory pattern were studied at various levels of PaCO2 and PaO2 in 8 anesthetized cats. A sudden rise in arterial pressure decreased both tidal volume and respiratory frequency. For a given increase in arterial pressure, the decrease in tidal volume was constant at all levels of PaCO2 and PaO2 examined, whereas the decrease in respiratory frequency became progressively lower as the level of chemical drive increased, regardless of the type of chemical stimuli. Analysis of respiratory duration revealed that the decrease in respiratory frequency during baroreceptor stimulation was solely due to prolongation of expiration. These observations were obtained in the intact as well as in the vagotomized animals but were not seen after bilateral sinus nerve section. They suggest that the central respiratory mechanisms controlling respiratory frequency are directly involved in the reduction in respiratory frequency during baroreceptor stimulation.

Glucagon radioimmunoassay with use of antiserum to glucagon C-terminal fragment

In this pancreatic-glucagon-specific radioimmunoassay we used C-terminal-region-specific antiserum. OAL-123, produced against a 19-29 C-terminal fragment of porcine glucagon. On measurement of pooled plasma the ranges for intra- and inter-assay coefficients of variation were 4.8-8.1% and 7.5-10.7%, respectively. The concentration of immunoreactive glucagon in plasma of healthy subjects, as measured with the OAL-123 assay system, was 87.9 (SD 23.8) ng/L. Measurement of the same plasma samples with the 30K assay system (30K being an antiserum highly specific for pancreatic glucagon) showed a comparable value, 86.2 (SD 26.3) ng/L. We followed changes in human and dog plasma immunoreactive glucagon concentrations on arginine infusion and after glucose load, using the OAL-123 and the 30K assay systems, with identical results. Combining other results of comparative immunochemical characterization of the OAL-123 and 30K assay systems, we confirmed that the antisera raised against the C-terminal fragment of glucagon can be used in radioimmunoassay of pancreatic glucagon.

Central hypoxic-hypercapnic interaction in mild hypoxia in man

Hypoxic-hypercapnic interaction in mild hypoxia was studied in 12 healthy males. Steady state ventilatory responses to hypercapnic-hypoxia [delta V(s)] were obtained as the difference in ventilation between hypoxia (mean values +/- S.D. of PETO2 = 7.36 +/- 0.20 kPa or of PaO2 7.10 +/- 0.41 kPa) and hyperoxia (PETO2 greater than 26.7 kPa) with the same degree of hypercapnia (PETCO2 6.12 +/- 0.22 kPa). On the other hand, withdrawal responses [delta V(w)] were obtained as the magnitude of depression in ventilation caused by two breaths of O2 from the above mentioned hypoxic hypercapnia. Averaged delta V(s) and delta V(w) were 9.57 +/- 5.45 and 6.45 +/- 4.90 l/min, respectively, the difference being statistically significant (P less than 0.01). Furthermore, if we assume the presence of ventilatory depression to be due to tissue PCO2 fall resulting from an increase in cerebral blood flow caused by hypoxia, the magnitude of central hypoxic-hypercapnic interaction was estimated to be as great as the value of delta V(w).

Glucagon radioimmunoassay with use of antiserum to glucagon C-terminal fragment

In this pancreatic-glucagon-specific radioimmunoassay we used C-terminal-region-specific antiserum. OAL-123, produced against a 19-29 C-terminal fragment of porcine glucagon. On measurement of pooled plasma the ranges for intra- and inter-assay coefficients of variation were 4.8-8.1% and 7.5-10.7%, respectively. The concentration of immunoreactive glucagon in plasma of healthy subjects, as measured with the OAL-123 assay system, was 87.9 (SD 23.8) ng/L. Measurement of the same plasma samples with the 30K assay system (30K being an antiserum highly specific for pancreatic glucagon) showed a comparable value, 86.2 (SD 26.3) ng/L. We followed changes in human and dog plasma immunoreactive glucagon concentrations on arginine infusion and after glucose load, using the OAL-123 and the 30K assay systems, with identical results. Combining other results of comparative immunochemical characterization of the OAL-123 and 30K assay systems, we confirmed that the antisera raised against the C-terminal fragment of glucagon can be used in radioimmunoassay of pancreatic glucagon.

Modification of laryngospasm in response to changes in PaCO2 and PaO2 in the cat

In order to study the effects of PaCO2 and PaO2 on the laryngeal closure reflex, changes in laryngeal resistance of the isolated cat larynx were measured before and during the stimulation of the superior laryngeal nerve (SLN) at various levels of PaCO2 and PaO2. The results showed that laryngeal resistance before SLN stimulation [LR (baseline)] increased slightly during hypocapnia. SLN stimulation produced laryngospasm which was defined as a sharp rise in the laryngeal resistance. Hypercapnia alone and hypoxia alone increased ventilation but decreased the degree and duration of laryngospasm due to SLN stimulation. On the other hand, hypocapnia augmented and prolonged the duration of this laryngospasm. These results suggest that PaCO2 and PaO2 regulate the laryngeal closure reflex in a way such that the degree of laryngospasm changes in inverse proportion to the activity of the respiratory center.

Responses of aortic chemoreceptors before and after pneumothorax in the cat

That the response of aortic chemoreceptors to hypercapnia is considerably smaller than that of carotid chemoreceptors is well accepted, but the mechanism for the difference is not known. It has been suggested that surgical exposure of the carotid body may contribute to the difference. Accordingly, the response of aortic body chemoreceptors to CO2 would be expected to resemble quantitatively that of carotid chemoreceptors after exposure of the aortic bodies by pneumothorax. The effect of opening the chest on aortic and carotid chemoreceptor responses to several levels of arterial CO2 and O2 tension and arterial blood pressure were studied in anesthetized cats. The activity of aortic chemoreceptors increased in spite of a decreased stimulus level in the thoracic cavity after pneumothorax. The activity remained higher than the control at all levels of arterial CO2 and O2 tension and arterial blood pressure. However, the slopes of CO2 response curves, which were initially small, did not change after pneumothorax. Thus a change in the normal environment of the aortic bodies by experimental manipulation did not cause the aortic chemoreceptor responses to resemble those of carotid chemoreceptors.

Production of antisera to des Asn28 Thr29 Homoser27-glucagon; the development of radioimmunoassay for total glucagon-like immunoreactivity in human plasma

Antisera having a strong and strictly constant cross-reactivity for gut-GLI were raised in seven rabbits immunized with immunogen, a conjugate of BSA and des-Asn28, Thr29, Homoser27 -glucagon (CNBr-glucagon). All of the anti-CNBr-glucagon sera exhibited titer and affinity for glucagon sufficiently high enough to develop a sensitive radioimmunoassay. The relative crossreactivity of the antisera to gut-GLI was comparable to that of antiserum K-4023 which strongly crossreacted with gut-GLI. One of the anti-CNBr-glucagon sera, OAL-196, did not react with the glucagon 19-29 fragment at all. The intra- and inter-assay coefficients of variation were 3.8-5.0 and 6.0-7.3%, respectively, in the radioimmunoassay system for total GLI in human plasma using OAL-196. The fasting plasma total GLI was 374 +/- 18 pg/ml. The plasma total GLI during 50 g oral glucose load in normal subjects increased significantly, whereas the plasma IRG level measured with the anti-glucagon 19-29 serum, OAL-123, assay system was lowered. In the gastrectomized subjects, plasma total GLI measured with the present assay system elicited a marked increase following an oral glucose load. These results suggest that the radioimmunoassay using anti-CNBr-glucagon sera will be useful in measuring plasma total GLI.

Comparison of aortic and carotid chemoreceptor responses to hypercapnia and hypoxia

A quantitative comparison of the responses between aortic and carotid chemoreceptors to steady-state levels of arterial CO2 and O2 partial pressure was made in 35 cats anesthetized, paralyzed, and artificially ventilated. The measurements on the two receptors were made simultaneously in 6 cats and separately in 29 cats. The response of aortic chemoreceptors to a CO2 stimulus was a fraction of that of carotid chemoreceptors, and the response to hypoxia was relatively blunted. The differences between the two chemoreceptors are quantitative rather than qualitative. Since a low arterial CO2 partial pressure stimulus is known to attenuate the hypoxic response of carotid chemoreceptors, it is suggested that the low CO2 response of aortic body chemoreceptors is responsible for their blunted hypoxic response.

Purification and properties of sterol-ester hydrolase from Saccharomyces cerevisiae

Sterol-ester hydrolase [EC 3.1.1.13] from Saccharomyces cerevisiae grown aerobically was solubilized with 1% Tween 20 and purified about 700-fold by the protamine sulfate treatment, DEAE-cellulose-, Sepharose 6B- and DEAE-cellulose column chromatographies. The molecular weight of the enzyme was estimated to be 70,000 by Sepharose 6B gel filtration. The enzyme activity showed two peaks of pH optimum at 4.4 and 6.8. Triton X-100 stimulated the activity as its low concentrations at both pH regions, but decreased the activity at its high concentrations at pH 6.8. The presence of Tween 20 or Tween 80 also stimulated the activity. These results were different from those in the previous report showing no stimulation of the crude enzyme by these detergents. The stimulation of the activity by phosphatidylcholine or low concentrations of lysophosphatidylcholine was similar to that by Triton X-100, and taurocholate was less effective than Triton X-100. The enzyme activity was inhibited by divalent cations such as Hg2+ and Cu2+.

Exaggerated response of plasma glucagon-like immunoreactivity (GLI) to oral glucose in patients with reactive hypoglycemia

In order to study the pathogenesis of reactive hypoglycemia, the responses of plasma glucose, IRI, glucagon immunoreactivity (GI) and total glucagon-like immunoreactivity (GLI) to 100 g oral glucose load were investigated in twenty-six patients of normal weight with reactive hypoglycemia. Of these patients, nineteen exhibited a diabetic OGTT curve. The findings in these patients were compared to normal control subjects (N = 20) and to disease-matched patients controls (N = 43). The psychological status was assessed by Cornell Medical Index Health Questionnaire in most of the subjects, who also received an x ray examination of the upper gastrointestinal tract. In addition, IVGTT was performed in the hypoglycemic patients. No apparent difference in plasma IRI response to oral glucose was observed between the hypoglycemic patients and their respective controls. Plasma total GLI concentrations were significantly increased during OGTT in both hypoglycemic groups. Following an oral glucose load, plasma GI levels were suppressed in the hypoglycemic groups to an extent similar to that in the control despite an apparent fall in their plasma glucose levels to the hypoglycemic range in the former. Radiological alterations in the upper gastrointestinal tract; deformity of the duodenal cap, gastric and/or duodenal ulcer, were found more frequently in the hypoglycemic groups. However, no characteristic change in personality was noticed in the patients. During IVGTT, neither plasma glucose nor total GLI level of the hypoglycemics differed from that of each control. The pathogenic factors responsible for reactive hypoglycemia will be discussed.

Subcellular localization of the enzymes involved in the late stage of ergosterol biosynthesis in yeast

The subcellular distribution of enzymes involved in the reaction sequence from zymosterol to ergosterol was studied. The spheroplasts obtained from cells aerobically grown on ethanol were gently disrupted and the homogenate was fractionated into the subcellular organelles by differential centrifugation. Inspection of the distribution of several marker enzymes revealed that the fractionation was reasonably effected. As a result of experiments, delta 8-delta 7-sterol isomerase, S-adenosylmethionine: delta 24-sterol methyltransferase and the enzyme involved in the reaction sequence from episterol to ergosterol were localized in microsomes. These results suggest the localization of enzymes involved in the late stage of ergosterol synthesis in microsomes.

Effects of dopamine on chemoreflexes in breathing

The effects of intravenous infusion of dopamine (20 microgram.min) on the steady-state ventilatory and carotid chemoreceptor responses to successive levels of isocapnic hypoxia and hyperoxic hypercapnia were investigated in cats anesthetized with alpha-chloralose. Dopamine infusion was followed by a maximal decrease in ventilation in about 20 s. Thereafter, the effect diminished and stabilized. Termination of dopamine infusion was promptly followed by an increase in ventilation. These ventilatory responses were smaller than the corresponding carotid chemoreceptor responses. The steady-state effect of dopamine infusion was to diminish ventilation at all levels of arterial O2 tension, the decrease being greater during hypoxia than that during hyperoxia. Bilateral section of the carotid sinus nerves significantly diminished but did not abolish the inhibitory effect of dopamine on ventilation during hyperoxia. Thus the ventilatory depression due to dopamine infusion is not entirely due to its effect on the carotid chemoreceptors. Dopamine decreased ventilatory responses to successive levels of hypercapnia by the same magnitude without changing the slope of the response curves. The steady-state relationship between chemoreceptor activity and ventilation shows that the ventilatory equivalent for carotid chemoreceptor activity is increased during dopamine infusion because of its greater inhibitory effect on carotid chemoreceptor activity than on ventilation with the decrease of arterial O2 tension.

Relative responses of aortic body and carotid body chemoreceptors to carboxyhemoglobinemia

The effects of carbon monoxide inhalation and of consequent carboxyhemoglobinemia (HbCO) on the discharge rates of aortic body and carotid body chemoreceptor afferents were investigated in 18 anesthetized cats. In 10 experiments both aortic and carotid chemoreceptor activities were monitored simultaneously. Carbon monoxide inhalation during normoxia always stimulated aortic chemoreceptors before carotid chemoreceptors, and the steady-state response of aortic chemoreceptors to HbCO was greater than that of most carotid chemoreceptors. Only 2 of the 18 carotid chemoreceptor fibers tested showed a distinct increase in activity in response to moderate increases in HbCO%. Thus, oxyhemoglobin contributed substantially to maintain tissue PO2 of all aortic chemoreceptors and of a few carotid chemoreceptors. Hyperoxia diminished the response of both aortic and carotid chemoreceptors to HbCO, indicating a lowered tissue PO2 as the stimulus source. We hypothesize that the aortic bodies have a much lower perfusion relative to their O2 utilization compared to the carotid bodies. As a consequence, the aortic chemoreceptors are able to act as a sensitive monitor of O2 delivery and to generate a circulatory chemoreflex for O2 homeostasis. carotid chemoreceptors monitor O2 tension and initiate strong reflex effects on the level of ventilation.

Wound-induced Ethylene Formation in Albedo Tissue of Citrus Fruit

Excised albedo tissue of citrus fruit (Citrus unshiu and Citrus hassaku) produced ethylene at an increasing rate in response to wounding and aging. The application of 1-aminocyclopropane-1-carboxylic acid (ACC) enhanced ethylene production in both the fresh and aged tissues, but this increase was greater in the aged tissue than in the fresh tissue. ACC content was very low in fresh tissue but increased greatly in aging tissue, paralleling the rise in ethylene production. Aminoethoxyvinylglycine (AVG) strongly inhibited ethylene production in the aged tissue. In the presence of ACC, however, ethylene production was not inhibited by AVG. These results suggest that ACC is an intermediate in the pathway of ethylene biosynthesis in the albedo tissue and that both steps of ACC formation and ACC conversion to ethylene are enhanced by wounding and aging. Inhibitors of protein synthesis, cycloheximide and 2-(4-methyl-2,6-dinitroanilino)-N-methyl propionamide, strongly inhibited ethylene production in the albedo tissue, implying that protein synthesis is required to maintain the continuous evolution of ethylene. The stimulation of ethylene production by ACC was reduced by the addition of l-methionine, whereas d-methionine had very little inhibitory effect. Ethylene production in the albedo tissue was also inhibited by the addition of n-propyl gallate and 3,5-dibromo-4-hydroxybenzoic acid.

Sympathectomy does not alter the response of carotid chemoreceptors to hypoxemia during carboxyhemoglobinemia or anemia

We tested the effects of section of the sympathetic innervation to the carotid body on the responses of single carotid chemoreceptor fibers to carboxyhemoglobinemia (40-50%) and anemia (15-20% Hct) at various levels of paO2 (range: 20-450 Torr). Sympathectomy had virtually no effect on the steady-state response curves of carotid chemoreceptors to O2, either in normal cats or in those with reduced oxygen transport due to anemia or carboxyhemoglobinemia.

A study of the physiological role of glucagon. Passive immunization with antiserum specific for pancreatic glucagon in rats

To investigate the physiological role of glucagon in the maintenance of euglycemia, the effect of the neutralization of glucagon by an antiserum specific for glucagon on blood glucose and C-peptide immunoreactivity (CPR) levels was studied in the basal as well as in the hyperglucagonemic states caused by hypoglycemia or an intravenous infusion of arginine in rats. The antiserum employed in this study was raised in rabbits by subcutaneous injection as a conjugate of BSA and the C-terminal fragment of glucagon. Since the antiserum was found to contain 896 ng/ml of antibody-bound glucagon, the antigen-stripped glucagon antibody was prepared. Its affinity constant and binding capacity were 2.57 x 10(10) M-1 and 147 nM, respectively. After the administration of 1 ml of the antiserum in 24-hr-fasted rats, no free immuno reactive glucagon (IRG) was detected during the experiment for 60 min. Likewise, antiserum treatment prevented a rise in the plasma IRG level following an arginine infusion and insulin-induced hypoglycemia. Plasma CPR levels tended to be lower in antiserum-treated rats than in the control in any conditions covered by the present study. However, changes in blood glucose levels the both groups were comparable. These results demonstrate that in the presence of glucagon antibodies euglycemia can be maintained with a reduced supply of insulin.

Inhibitory and excitatory effects of dopamine on carotid chemoreceptors

The effect of intravenous dopamine on carotid body chemoreceptor activity was investigated in 6 anesthetized cats which were paralyzed and artificially ventilated. Studies were performed at 4 steady-state PaO2 levels at a constant PaCO2 and at 4 levels of PaCO2 during hyperoxia. Dopamine inhibited carotid chemoreceptors before and excited them after haloperidol. Moderate stimulation of the receptors by hypoxia and hypercapnia augmented dopamine's effects. These results indicate that both inhibitory and excitatory dopamine receptors are present in the carotid body.

Changes in the respiratory pattern induced by halothane in the cat

The effect of halothane on the respiratory pattern was investigated in lightly anaesthetized cats. Following the administration of 2.0% halothane there was a transient increase in respiratory frequency because of a decrease in the duration of expiration, followed by a progressive decrease in respiratory frequency as a result of prolongation of inspiration; both events could be demonstrated before and after vagotomy. During the steady state obtained following the administration of 0.5, 1.0 and 1.5% halothane and after vagotomy there was a decrease in the duration of expiration and a progressive increase in the duration of inspiration. Tidal phrenic output decreased progressively as the concentration of halothane was increased. These results suggest that changes in respiratory pattern seen during halothane anaesthesia might involve some excitatory central mechanisms other than the bulbopontine system.

Cronkhite-Canada syndrome associated with sigmoid cancer case report and review of 54 cases with the syndrome

The case of a 78-year-old man with the characteristic clinical and pathologico-anatomic pictures of the Cronkhite-Canada syndrome associated with sigmoid cancer is reported. He died ten months after the onset of his disease. Autopsy findings of the patient are described in detail. The other fifty three cases of the syndrome are reviewed, and clinical and pathologico-anatomic features of the Cronkhite-Canada syndrome are discussed.

Heterogeneity of plasma motilin in patients with chronic renal failure

Plasma immunoreactive motilin (IRM) concentrations were strikingly higher in patients with chronic renal failure (CRF) than in normal subjects. IRM in azotemic plasma was heterogeneous in gel-filtration profile. The first peak eluted in the void volume of the column and the second and the third one, comprising a major portion of IRM content, came out coincidentally with insulin and authentic motilin, respectively. By contrast, no discernible amount of IRM was found in the region corresponding with the second peak in gel-filtration of the plasma from normals and very little in a patient with ileus whole plasma IRM level was elevated. The hypermotilinemia and the accumulation of this high molecular weight motilin in patients with CRF suggest that the kidney plays some role in the elimination of motilin, and further, that the clearance of the high molecular motilin is more dependent on renal function than that of authentic motilin. The present paper emphasizes the necessity for clarifying the significance of the heterogeneity of IRM in CRF.

Interaction of dopamine and haloperidol with O2 and CO2 chemoreception in carotid body

Effects of dopamine and of a dopaminergic blocker, haloperidol, on the responses of carotid body chemoreceptors to hypoxia and hypercapnia were investigated in 16 anesthetized cats. Intravenous infusion of dopamine (10-20 micrograms.min-1) decreased carotid body chemoreceptor responses to hypoxia and hypercapnia. The effect was greater at higher levels of arterial oxygen and carbon dioxide tension (PaO2 and PaCO2) stimulus. Thus, the magnitude of the dopamine effect depended on the degree of both PO2- and PCO2-mediated excitation of the receptors. Haloperidol potentiated responses to both hypoxia and hypercapnia but apparently did not stimulate the receptors in the absence of these stimuli. Potentiation by haloperidol and inhibition by dopamine of excitatory effects due to PaO2 decrease and PaCO2 increase are complementary. The data suggest that chemoreception of dopamine, O2, and CO2 converge at some site in the carotid body. Persistence of hypoxic and hypercapnic responses, following dopamine-blocking doses of haloperidol, does not support the theory that regulation of dopamine release is responsible for O2 and CO2 chemoreception in carotid body of the cat.

Biosynthesis of ergosterol in cell-free system of yeast

We previously proposed the occurrence of multiple pathways in the ergosterol biosynthesis of yeast, based on the results of examination of 14C-incorporation into sterols from L-[methyl-14C]methionine which was given to the intact cells of yeast. This led us to investigate the validity of the pathways by experiments with the cell-free system. Highly active cell-free extracts could be prepared by disruption of yeast cells with a Vibrogen Cell Mill in the presence of 0.1 mM dithiothreitol. This preparation catalyzed 14C-incorporation from [14C]methionine into ergosterol with a high yield. This preparation was found to be favorable for elucidation of ergosterol synthesis, since only a small amount of radioactivity was incorporated into fatty acid ester form of sterols which were reported to be inactive as a substrate for sterol synthesis reaction. Time course experiment of 14C-incorporation from [14C]methionine into various sterols under aerobic conditions showed that ergosta-8,24(28)-dien-3 beta-ol was a precursor for ergosta-7,24(28)-dien-3 beta-ol and that radioactivities were converted through ergosta-5,7,24(28)-trien-3 beta-ol and ergosta-5,7,22,24(28)-tetraen-3 beta-ol into ergosterol with time. In contrast, similar experiments under anaerobic conditions showed that ergosta-7,24(28)-dien-3 beta-ol accumulated and very little conversion of radioactivity into ergosterol occurred. In addition, the results indicated that oxygen was required for the introduction of double bond into 22 position as well as into 5 position. The results obtained with the cell-free system supported the validity of the proposal of multiple pathways of ergosterol synthesis in the intact cells.

[Experimental studies on administration method of chemotherapeutic agents. 16. Effect of polymyxin B against Pseudomonas aeruginosa (author's transl)]

The most effective administration method of polymyxin B (PL-B), a peptide antibiotic, has been studied in the experimental mice infection with Pseudomonas aeruginosa. 1) Pseudomonas aeruginosa damaged by PL-B, when the drug was free, immediately began to regrow in vitro. 2) the therapeutic efficacy of PL-B on multiple administration was less effective than its single administration. 3) An important factor to decide the therapeutic efficacy of PL-B was the high drug concentration in plasma and peritoneal fluid.

Relative responses of aortic body and carotid body chemoreceptors to hypotension

Responses to acute arterial blood pressure changes of a single or a few chemoreceptor afferents from the aortic body and carotid body at constant arterial blood gases and pH were measured in 16 adult cats. During normocapnic normoxia and moderate hypoxia (arterial oxygen tension of 60 Torr) an induced hypotension of 80 Torr increased strikingly the discharge rate of all aortic chemoreceptors but not of most carotid chemoreceptors; hypotension down to the level of 50 Torr stimulated most carotid chemoreceptors only slightly. Hyperoxia eliminated the stimulatory effect of this degree of hypotension on carotid chemoreceptors; it did not affect aortic chemoreceptors to the same extent. Hypoxia augmented the effect on aortic chemoreceptors more than the effect on carotid chemoreceptors. Thus the effect of hypotension was dependent on arterial oxygen tension. The greater effect of hypotension on aortic body chemoreceptor activity indicates a greater normal circulatory constraint for the aortic body. Accordingly, aortic chemoreceptors are more suited to monitor circulatory changes in O2 flow, and carotid chemoreceptors are more suited to monitor arterial gas pressure changes due to respiration.

Chemical modifications of D-amino acid oxidase. Evidence for active site histidine, tyrosine, and arginine residues

1. D-amino acid oxidase is inactivated by reaction with a low molar excess of dansyl chloride at pH 6.6, with complete inactivation accompanied by incorporation of 1.7 dansyl residues per mol of enzyme-bound flavin. The presence of benzoate, a potent competitive inhibitor, protects substantially against inactivation. Evidence is presented that the inactivation is due to dansylation of an active site histidine residue. Reactivation may be obtained by incubation with hydroxylamine. Diethylpyrocarbonate also inactivates the enzyme and modifies the labeling pattern with dansyl chloride. 2. Butanedione in the presence of borate reacts rapidly to inactivate D-amino acid oxidase. Reactivation is obtained spontaneously on removal of borate, implicating reaction of butanedione with an active site arginine residue. 3. Fluorodinitrobenzene appears to behave as an active site-directed reagent when mixed with D-amino acid oxidase at pH 7.4. Complete inactivation is obtained with incorporation of 2.0 dinitrophenyl residues per mol of enzyme-bound flavin. Again benzoate protects against inactivation; only one dinitrophenyl residue is incorporated in the presence of benzoate. The active site residue attacked by fluorodinitrobenzene has been identified as tyrosine.

Relative latency of responses of chemoreceptor afferents from aortic and carotid bodies

Discharges from aortic and carotid body chemoreceptor afferents were simultaneously recorded in 18 anesthetized cats to test the hypothesis that aortic chemoreceptors, because of their proximity to the heart, respond to changes in arterial blood gases before carotid chemoreceptors. We found that carotid chemoreceptor responses to the onset of hypoxia and hypercapnia, and to the intravenously administered excitatory drugs (cyanide, nicotine, and doxapram), preceded those of aortic chemoreceptors. Postulating that this unexpected result was due to differences in microcirculation and mass transport, we also investigated their relative speed of responses to changes in arterial blood pressure. The aortic chemoreceptors responded to decreases in arterial blood pressure before the carotid chemoreceptors, supporting the idea that the aortic body has microcirculatory impediments not generally present in the carotid body. These findings strengthened the concept that carotid bodies are more suited for monitoring blood gas changes due to respiration, whereas aortic bodies are for monitoring circulation.

Effects of chemical drive on the inhibition of respiration produced by laryngeal stimulation in cats

In 8 anesthetized cats the acute respiratory responses to laryngeal stimulation were studied under various levels of chemical drive. Under air breathing condition with strong stimulation the animals showed either cough or apnea, whereas with relatively weak stimulation the animals showed smooth reduction in respiration due to a decrease in tidal volume and prolongation of both inspiratory and expiratory time. Although the inhibitory effect of laryngeal stimulation on tidal volume was independent of the level of chemical drive, the inhibition of respiration, when analyzed in terms of decrease in the minute ventilation, was greater the higher the chemical drive regardless of the type of chemical stimulus. Although bilateral vagotomy decreased the threshold of stimulus intensity for changes in respiratory pattern, especially under hypoxia, the effects of laryngeal stimulation on respiratory pattern in vagotomized animals were qualitatively similar to those obtained in the intact animals. We concluded that laryngeal stimulation has a direct action on the central respiratory mechanism regulating respiratory duration and that the interaction between laryngeal stimulation and chemical drive causes multiplicative inhibitory effects on ventilation.

Regulatory nucleotides involved in the Rel function of Bacillus subtilis

We have examined the accumulation of polyphosphorylated nucleotides in Bacillus subtilis in relation to the function of the rel gene. Our results are as follows. (i) During inhibition of isoleucine activation by O-methylthreonine, wildtype B. subtilis cells accumulate unusual nucleotides with the chromatographic and chemical properties of pppApp, ppApp, pppGpp, ppGpp, pGpp, and ppGp. (ii) During the carbon source downshift elicited by inhibiting glucose uptake, we observed accumulation of the polyphosphorylated guanosine but not adenosine nucleotides. (iii) At the end of long phase in sporulation medium, we observed a small transient accumulation of the polyphosphorylated guanosine but not adenosine nucleotides. (iv) We were unable to detect a nucleotide with chromatographic behavior expected for pppAppp under any conditions. (v) The rel mutant of Swanton and Edlin (Biochem. Biophys. Res. Commun. 46-583-588, 1972) did not accumulate any of these polyphosphorylated nucleotides under any of the conditions examined. (vi) the rel mutant is unimpaired in sporulation. We conclude that one or more of the nucleotides we have detected may be involved in controlling the specificity of transcription during the stringent response, but none of them are required for sporogenesis.

Aortic body chemoreceptor responses to changes in PCO2 and PO2 in the cat

Responses of aortic chemoreceptor afferents to a range of arterial carbon dioxide tension (Paco2) changes at various levels of arterial oxygen tension (Pao2) were investigated in 18 cats anesthetized with alpha-chloralose and maintained at 38 degrees C. Aortic chemoreceptor activity, end-tidal oxygen pressure, end-tidal carbon dioxide pressure, and arterial blood pressure were continuously monitored. Arterial blood gases were measured in steady states. Single or a few clearly identifiable afferents were studied during changes and steady states of Pao2 and Paco2. All the aortic chemoreceptor afferent discharge rates increased with Paco2 increases from hypercapnia (10-15 Torr) to normocapnia and moderate hypercapnia (30-50 Torr) and with Pao2 decreases from above 400 to 30 Torr. Hypoxia augmented the response to Paco2 most effectively in the range of 10-40 Torr. At any Pao2, the discharge rate reached a plateau with sufficient intensity of hypercapnia. The Paco2 stimulus threshold at a Pao2 of 440 Torr was about 15 Torr, and at a Pao2 of 60 Torr it was 10 Torr. In the transition from hypocapnia to hypercapnia, responses increased gradually, usually without an overshoot. The steady-state responses to Paco2 of the majority of aortic chemoreceptors resembled those of carotid chemoreceptors. The responses of both receptors can be attributed to the same basic type of mechanism.

Studies on delta8-delta7 isomerization and methyl transfer of sterols in ergosterol biosynthesis of yeast

The formation of cholesta-7,24-dien-3 beta-ol and its activity as a substrate for the sterol side-chain methyltransferase in yeast have not previously been studied. Experiments with acetone-powder extracts of yeast showed that the sterol is formed from zymosterol by delta8-delta7 isomerization. However, direct conversion of cholesta-7,24-dien-3 beta-ol into zymosterol could not be demonstrated. The reversibility of the reaction was proved by the detection of 3H-incorporation into cholesta-8-en-3 beta-ol (with lathosterol as a carrier) from [3H]H2O in the medium. Incubation of cholesta-7,24-dien-3 beta-ol and S-adenosyl-L-[methyl-14C]methionine with the acetone-powder extract resulted in methylation of the sterol to form episterol. Similar incubation of zymosterol gave fecosterol and episterol, suggesting that fecosterol initially formed by the methylation was isomerized to episterol. In intact cells, however, an alternative pathway (zymosterol yields cholesta-7,24-dien-3 beta-ol yields episterol) may also operate. The relative importance of the two pathways is not known.

Studies on the delta 5-desaturation in ergosterol biosynthesis in yeast

Studies were carried out on the delta 5-desaturation reaction in ergosterol biosynthesis with a particulate fraction of cell-free extract of yeast. A reduced pyridine nucleotide coenzyme and molecular oxygen were required for the reaction. It was shown that the enzyme activity is located in a fraction corresponding to microsomes. The reaction was inhibited by KCN, but not by CO. Menadione and potassium ferricyanide inhibited the NADPH- and NADH-dependent reactions, respectively, and cytochrome c inhibited both of them. These results suggested an involvement in delta 5-desaturation of a mixed function oxidase system resembling that for the fatty acyl-CoA desaturation reaction.

Production of anti-glucagon sera with a C-terminal fragment of pancreatic glucagon

The C-terminal region-sepcific anti-glucagon sera were raised in rabbits using as immunogen, and conjugate of BSA and a C-terminal fragment of pancreatic glucagon. The hapten was prepared by trypsin digestion of the glucagon, which was proved to be a 1:3 mixture of glucagon (18--29) and (19--29). Six rabbits were immunized by subcutaneous injection of an emulsion of the conjugate with complete Freund's adjuvant and five of the rabbits produced antibodies to the glucagon (GC-1, GC-2, GC-3, GC-5 and GC-6). For comparison, rabbit antisera were also produced against glucagon polymer (GA-10) and syrupy glucagon fibrils (PGA-2). All these antisera as well as the pancreatic glucagon-specific antiserum 30 K were characterized with dog gut-extract (gut-GLI) and glucagon-related peptide fragments in the radioimmunoassay systems. The assay systems utilized 125 I-monosubstituted pancreatic glucagon as tracer and human mono-component glucagon as standard. All sera of the GC-series crossreacted with the dog gut-extract very weakly and antisera GC-5 and GC-6 exhibited the lowest crossreactivities with the extract, which were shown to be as low as that of 30k. Characterization of the antiserum GC-5 with purified glucagon related fragments indicated that the major antigenic determinant located exactly in the C-terminal region of glucagon. The present results clearly showed high efficiency of the use of the glucagon C-terminal fragment as hepatenic immunogen in obtaining the C-terminal region-specific, i.e., pancreatic glucagon-specific antisera.

A quantitative evaluation for peripheral respiratory chemosensitivities by the withdrawal test in man

Ten healthy subjects were tested for their peripheral respiratory chemosensitivities by the withdrawal technique two times on separate days. Hypoxic hypercapnia of PET, O2 75, 65 AND 55 mmHg with PET, CO2, 5 mmHg higher than the control level was replaced by 100% O2 two times with spontaneous respiration. Then, breath-by-breath depression calculated in minute ventilation (delta V) was observed during the period 5-20 sec after the first O2 inhalation. The results were analyzed by the linear relationship between PET, O2 and 1n delta V, and PaO2 and 1n delta V. Delta V at P02 50 mmHg, delta V50, was 9.09 +/- 6.81 liters/min (mean +/- SD) in PET, O2-1n delta V analysis and 9.22 +/- 7.46 liters/min in PaO2-1n delta V analysis, respectively. The averaged day to day variation of delta V50 expressed by SE in % was 5.3% in PET, O2-1n delta V analysis and 11.5% in PaO2-1n delta V analysis, respectively.