[The mechanism of the decrease in serum potassium during insulin-induced hypoglycemia (author's transl)]

This study was made to investigate the mechanisms of the changes in serum potassium during a period of insulin-induced hypoglycemia. The following experiments were performed: I) A relationship was observed between the amount of insulin dosage and the levels of serum potassium, blood sugar, and plasma cyclic AMP or plasma cyclic GMP in normal controls and rats. In humans, regular insulin (0.025 approximately 0.15 U/kg) was injected intravenously, and blood samples drawn at intervals were used for estimation. Regular insulin (0.1 approximately 1.0 U/kg) was injected into Wistar strain male rats and blood was drawn at intervals. II) A relationship was observed between those items mentioned above in patients with thyroid diseases or diabetes mellitus. They were injected with regular insulin (0.1 U/kg). III) An effect of spironolactone was observed on the levels of the above mentioned items. Regular insulin (0.075 U/kg) was injected into normal controls after the ingestion of spironolactone. IV) An effect of non-selective beta-blocker was observed on the levels of the above mentioned items. Regular insulin (0.1 U/kg) was injected into normal controls and patients with hyperthyroidism after the ingestion of 20 mg of propranolol. The results obtained were as follows: 1) There was a significant logarithmic dose-response relationship between insulin dose and maximum per cent decrease in serum potassium, and maximum per cent increase in plasma cyclic AMP. (p less than 0.02 approximately 0.01) 2) A significant positive correlation was observed between the maximum per cent decrease in serum potassium and the maximum per cent increase in plasma cyclic AMP during the period of insulin-induced hypoglycemia. (p less than 0.001) 3) The changes in serum potassium and plasma cyclic AMP were significantly greater in patients with hyperthyroidism who were possibly in a hyperdynamic beta-adrenergic circulatory state, and these changes were smaller in patients with hypothyroidism than in the normal controls. When their thyroid functions were normalized by the treatment, the changes in serum potassium and plasma cyclic AMP behaved in the same manner as those in the normal controls. 4) Spironolactone had no effect on any change observed in this study. 5) Neither per cent decrease of serum potassium nor per cent increase of cyclic AMP were influenced by propranolol at 15 minutes, but they decreased 30 minutes after the insulin injection. These results may indicate that a decrease of serum potassium levels during the period of insulin-induced hypoglycemia in both the early and late phases is caused by different mechanisms. The change in serum potassium was accompanied by an increase of plasma cyclic AMP, and furthermore this change was inhibited by beta-blocker. It was suggested that beta-adrenoreceptor play a role in a decrease of serum potassium, especially 30 minutes after a injection of insulin.

Evaluation of ototoxicity of amino-glycoside antibiotics in rabbits

It is generally accepted that the ototoxicity of aminoglycoside antibiotics is gentamicin (GM) greater than dibekacin (DKB) greater than kanamycin (KM) greater than amikacin (AMK) based on the results of animal experiments. However, clinical data reveals that the ototoxicity caused by each of the aminoglycoside antibiotics does not coincide with the ototoxicity in the animals. The present study was intended histopathologically for comparative evaluation of above-mentioned antibiotics using rabbits. The ototoxicity was GM greater than DKB greater than KM greater than AMK with the dose of 100 mg/kg, which coincide with many of the conventional reports on animal experiments. However, with the dose of 50 mg/kg, the order was GM greater than AMK greater than KM greater than DKB. With the dose of 30 mg/kg, hardly any differences were noted between the ototoxicity of GM and that of AMK. It was found out that the evaluation of the ototoxicity of drugs in high doses does not always correspond to that of lower doses. Therefore, the ototoxicity should be evaluated in strict consideration of dose of drugs. Usually, the doses of drugs used in the ototoxicity studies with animals are more than 10 times higher than those used clinically. Consequently, problems still exist in infering the ototoxicity of drugs in humans directly from the results obtained from animal experiments.

Ototoxicity of aminoglycoside antibiotics by rapid intravenous injection

The ototoxicity and nephrotoxicity of aminoglycoside antibiotics (dibekacin, gentamicin and kanamycin) administered to rabbits by rapid intravenous or intramuscular injections were histopathologically compared. Comparative evaluations between the two routes were further made concerning the levels of the antibiotics in serum and in perilymph. The results revealed that, although the peak serum level after a rapid intravenous injection was significantly higher than that observed after an intramuscular injection, no differences in the transfer into the perilymph, and in inner ear or renal damage were seen between the two different routes. In other words, the results of the present study did not support the conventional idea that the higher the peak blood levels of the aminoglycoside antibiotics, the greater the risk of damage to the inner ear or kidney.

Direct stimulatory effect of histamine on aldosterone secretion of the perfused dog adrenal gland

The left adrenal gland of the hypophysectomized-nephrectomized dog was perfused in situ with the blood from the femoral artery of the hypophysectomized-nephrectomized donor dog. After infusion of histamine (0.1 mg/min for 5 min) into the arterial inflow circuit, the rates of secretion of aldosterone, corticosterone and cortisol (ng/100 mg adrenal wt. each min) increased from the basal level of 0.66+/-0.21 (mean+/-S.E.M.) to 2.24+/-0.45 at 10 min, from 4+/-1 to 20+/-4 at 5 min and from 19+/-5 to 64+/-15 at 5 min, respectively. The maximal increments above the basal value after the infusion of histamine in the secretory rates of aldosterone, corticosterone and cortisol were 51, 16, and 13% that of the respective steroid after the infusion of ACTH (20mIU/min for 5 min). The results indicate that histamine has a direct stimulatory effect on the secretion of aldosterone by the adrenal gland as well as on that of corticosterone and cortisol.

Adrenal secretion of aldosterone in response to anaphylactic shock in hypophysectomized-nephrectomized dogs

The adrenal secretion of aldosterone in response to anaphylactic shock was examined in intact and hypophysectomized-nephrectomized dogs which had been sensitized by horse serum injections (s.c. and i.v.) 24-30 days before the experiment. On the day of the experiment, dogs were injected intravenously with horse serum under pentobarbital anesthesia. During anaphylactic shock induced by horse serum, the adrenal secretion of aldosterone in intact and hypophysectomized-nephrectomized dogs increased from 1.32 +/- 0.55 (mean +/- S.E.M.) to 8.43 +/- 1.99 ng/(kg.min) and from 0.23 +/- 0.10 to 2.38 +/- 0.63 ng/(kg.min), respectively. Plasma potassium concentration increased slightly and plasma sodium concentration did not change after the injection of horse serum in hypophysectomized-nephrectomized dogs. The results suggest the possibility that the adrenal secretion of aldosterone in response to anaphylactic shock in hypophysectomized-nephrectomized dogs is due mainly to a direct effect of histamine on the adrenal cortex or occurs via some unknown factors, and only in a small part to an increase in plasma potassium concentration. The adrenal secretion of corticosterone and cortisol during anaphylactic shock increased slightly but significantly in hypophysectomized-nephrectomized dogs, whereas it increased markedly in intact dogs.

Direct effect of histamine on the production of adrenocortical hormone by guinea-pig adrenal cells

In trypsin-dispersed adrenal cells of the guinea-pig, the production of 11-hydroxycorticosteroids in vitro was found to be significantly stimulated by 10(-7) -10(-4)M histamine and the maximum steroidogenic response (1.7-fold increase in 11-hydroxycorticosteroid production) was observed at 10(-6)M. The stimulatory action of histamine on steroidogenesis was blocked by cycloheximide treatment.

Effects of prostaglandin E2 and dibutyryl cyclic AMP on the histamine-induced production of cortisol and corticosterone in isolated canine adrenal cells

The steroidogenic effect of histamine in isolated adrenocortical cells of the dog was investigated in the presence of prostaglandin E2 (PGE2) and/or dibutyryl cyclic AMP (dbcAMP) in the medium. The effect of histamine, in combination with PGE2 was less than their total individual effects in the production of cortisol, but not ofcorticosterone. With dbcAMP the effect was just equal to them. However, the combination of histamine, PGE2 and dbcAMP showed an increase twice that of their total individual effects in the production of both steroids. These results indicate that, in the dog, histamine, PGE2 and dbcAMP may act synergistically in the adrenocortical cells.

Enzyme immunoassay of angiotensin I

A very sensitive and specific enzyme immunoassay has been developed for angiotensin I. Angiotensin I was coupled to beta-D-galactosidase by a novel cross-linking reagent, N-(meta-maleimidobenzoyloxy)succinimide. No decrease in the enzyme activity was observed during the coupling procedure. In the angiotensin I-beta-D-galactosidase conjugate, 0.39 mol immunoreactive angiotensin I/mol enzyme were present. A competitive assay with the enzyme-labeled angiotensin I was performed. Antibody-bound and free labeled antigen were separated from each other by the second antibody method, and the enzyme activity of the former was estimated. Using this assay, angiotensin I could be detected in the range of 1.2--50 pg. The sensitivity was 4.5-fold higher than that of the usual RIA. This assay distinguished clearly angiotensin I from angiotensin II, angiotensin III, and (Sar1, Ile8)-angiotensin II. The present method was applied to measure PRA in dogs; the results correlated fairly well with those obtained by the RIA (r = 0.94).

Effects of anti-inflammatory drugs on platelet aggregation in rabbits

Effects of non-steroidal anti-inflammatory drugs (aspirin, indimethacin, flufenamic acid, tiaramide and HG-70) on rabbit platelet aggregation were studied using Evans aggoregometer and a modified form of Chandler's loop method. Tiaramide in 10(-4) and 10(-5)M inhibited effectively the aggregation caused by ADP in the optical density method and accelerated the restoration of the time course of disaggregation in the loop method. The other 4 drugs were ineffective. In collagen-induced aggregation all 5 drugs inhibited the aggregation. Among them tiaramide was most potent. Only tiaramide prolonged the time taken to induce snow storm and aggregates in the loop method.

Secretion of aldosterone in response to histamine in hypophysectomized-nephrectomized dogs

In hypophysectomized-nephrectomized dogs after intravenous injection of histamine, a marked increase was observed in the rate of secretion of aldosterone, although it was smaller than that in intact dogs. Hypophysectomy plus bilateral nephrectomy greatly impaired the secretion of corticosterone and cortisol in the dog in response to histamine. However, a small yet significant increase in corticosterone and cortisol secretion was observed in hypophysectomized-nephrectomized dogs after intravenous injection of histamine. Additional experiments showed that plasma concentrations of potassium and sodium in hypophysectomized-nephrectomized dogs remained unchanged after intravenous injection of histamine. These results suggest that histamine stimulates aldosterone secretion in the dog partly by a direct effect on the adrenal cortical cells, whereas the effect of histamine on corticosterone and cortisol secretion is mediated mainly, but not totally, by pituitary release of ACTH.

Clinical application of breath analysis for dimethyl sulfide following ingestion of DL-methionine

After overnight-fasting, the concentration of dimethyl sulfide in expired alveolar gas (alv-DMS) was determined serially following ingestion of 2 g of DL-methionine in normal subjects and patients with liver diseases. Alv-DMS rose to a peak in 30 to 90 min, declined markedly within 3 h, and then decreased gradually. Half-disappearance times (T 1/2) (mean +/- S.E. min) in each experimental group were: normal (N = 9) 61.7 +/- 4.7, acute hepatitis (N = 6) 62.5 +/- 6.8, chronic hepatitis (N = 10) 84.0 +/- 13.0, and liver cirrhosis (N = 13) 159.2 +/- 30.4, respectively. Cirrhotics had a T 1/2 significantly longer than that of the other three groups: vs. normal P less than 0.02, vs. acute hepatitis P less than 0.05, and vs. chronic hepatitis P less than 0.05. T 1/2 of alv-DMS following ingestion of DL-methionine seems to be of clinical interest.

Inhibitory effect of tiaramide on ADP-induced aggregation in rabbit platelets

Tiaramide in 10(-4) or 10(-5) M depressed the ADP-induced aggregation of rabbit platelets using the turbidimetric method. In modified Chandler's loop method, tiaramide in the same concentration accelerated the restoration of the time course of disaggregation.

Enzyme immunoassay of viomycin. New cross-linking reagent for enzyme labelling and a preparation method for antiserum to viomycin

A new cross-linking reagent of the hetero-bisfunctional type, a N-(maleimidobenzoyloxy)-succinimide (MBS) was prepared and used for enzyme labelling of viomycin under mild aqueous conditions by a two-step process. In the first step a maleimide residue was selectively introduced onto the N1-amino group of viomycin with a limited amount of MBS. The second step consisted of thioether formation between the maleimide residue and free thiol groups of beta-D-galactosidase. An antiserum to viomycin was raised in rabbit by immunization with a viomycin-BSA conjugate. The conjugate was prepared by protecting N6-amino group of viomycin with an acetyl group and succinylating the N1-amino group, activating the carboxyl group by a mixed anhydride method and coupling it with the amino groups of bovine serum albumin (BSA). The specificity of the antiserum was proved by an enzyme immunoassay based on the competition between viomycin and its enzyme conjugate toward diluted solutions of the antiserum. By use of the viomycin-enzyme conjugate and the antiserum to viomycin, enzyme immunoassay of viomycin was successfully performed by the competitive binding procedure with the double-antibody method, and 0.1 to 4 ng of the antibiotic could be detected.

Direct effect of histamine on cortisol and corticosterone production by isolated dog adrenal cells

Department of Physiology, Nagasaki University School of Medicine, Nagasaki, Japan

(Received 2 September 1977)

In the dog, intravenous injection of histamine produces a marked increase in adrenocortical secretion (Suzuki, Hirai, Yoshio, Kurouji & Yamashita, 1963; Papp, Stark, Ács & Varga, 1964; Asano, 1966; Katsuki, Ito, Watanabe, lino, Yuji & Kondo, 1967; Tanigawa, 1967; Narita, 1971; Yamashita, Shimizu, Mieno & Kawao, 1973; Hirose, Matsumoto & Suzuki, 1976; Hirose, Matsumoto, Aikawa & Suzuki, 1977). The adrenocortical response of the dog to histamine was found to be markedly reduced, although not completely eliminated, by hypophysectomy (Hirose et al. 1976, 1977). This indicates that the response, although dependent for the main part on the pituitary gland, may involve a direct effect of histamine on the adrenal cortex or some other extrapituitary factor. In the present study, a direct stimulatory effect of histamine on the adrenal cortex was examined by evaluating the production of cortisol

Difference of hepatic circulation between alcoholic and non-alcoholic hepatic cirrhosis

Comparisons were made of hepatic circulation between alcoholic and non-alcoholic cirrhosis. The wedged hepatic venous pressure and per cent intrahepatic shunt measured by the method of continuous infusion of D-galactose-1-14C were similarly markedly increased. On the other hand, the wedged hepatic venography showed the main portal trunk and extrahepatic collaterals, namely, the tendency of reverse or stagnant portal flow, more frequently in alcoholic cirrhosis than in non-alcoholic cirrhosis. The nodules shown by slow low-pressure hepatic sinusoidography were larger in non-alcoholic cirrhosis than in alcoholic cirrhosis.

Alcoholic hepatitis with and without alcoholic hyaline

Sixteen cases of alcoholic hepatitis with alcoholic hyaline (Group I) and 13 cases without alcoholic hyaline (Group II) have been collected since 1970. These were most frequently found in the fifth decade in both groups. One female was found in Group I. Cases of about two-thirds of both groups were comsumers of 110 g or more of alcohol per day. No significant differences except fever and erythrocyte sedimentation rate were found in clinical and laboratory changes between both groups. Fatty change in liver biopsy specimens were more frequently seen in Group I than in Group II. The wedged hepatic venous pressure was markedly elevated in alcoholic hepatitis with cirrhosis and moderately elevated in alcoholic hepatitis without cirrhosis. Wedged hepatic venography showed the main portal trunk and extrahepatic collaterals, namely, reversal of the portal flow or such tendency in 2 out of 5 patients of Group I.

Purification and properties of the adenosine deaminase from the midgut gland of a marine bivalved mollusc, Atrina spp

1. The adenosine deaminase has an approximate molecular weight of 130,000-140,000 and the composition of two polypeptide units (mol. wt about 68,000) is suggested, by means of SDS disc electrophoresis. 2. Both the alpha (Vm/Km) and beta (Vm) parameters were varied with pH and temperature. RSS (relative substrate specificity) adenosine and deoxyadenosine values for alpha and beta were 1.2 and 1.1, respectively. 3. Adenine, 2'-, 3', 5'-AMP, 5'-deoxyAMP, ADP and ATP were not deaminated by the enzyme. 4. Inhibition by Mg2+ was found in reaction with adenosine at pH 8 but not with deoxyadenosine at the same pH. Mn2+, which did not affect the reaction rate at pH 4 and 5, showed competitive inhibitory effects at pH 6, 7 and 8.

Unusual Enterobacteriaceae: H2S+ Shigella sonnei, one authentic and one false positive due to contamination with the obligate anaerobe Eubacterium lentum

A mixture of Shigella sonnei and Eubacterium lentum produced H2S in triple sugar iron agar; however, neither produced any in pure culture. A second culture of S. sonnei, isolated in Japan, is thought to be the first documented H2S+ Shigella.

Enzyme coupled immunoassay of insulin using a novel coupling reagent

A novel coupling reagent, meta-maleimidobenzoyl N-hydroxysuccinimide ester was synthesized. Using this reagent, insulin was conjugated very easily with beta-D-galactosidase [EC 3.2.1.23] in neutral, aqueous solution. No reduction of the enzyme activity was observed during the coupling procedure. The competitive bindings of the conjugate and insulin to anti-insulin serum were tested. The results indicated that the conjugate has enough immune reactivity for use in enzyme coupled immunoassay. Using this assay 20-800 pg of insulin were detectable.