Shigeru Matsukura

Cotinine excretion and daily cigarette smoking in habituated smokers

A sensitive and specific radioimmunoassay of cotinine, a major metabolite of nicotine, was developed using an antiserum raised against ∓‐1‐(β‐aminoethyl)‐cotinine coupled to bovine serum albumin (BSA) and l25I‐cotinine derivative. Inhibition studies with related compounds of cotinine revealed that the antiserum was not only specific for both the pyrrolidine and the pyridine ring but also highly reactive to the side chain attached to the latter ring for preparing the antigen and the labeled derivative of cotinine. The minimum detectable amount of cotinine was 1 ng. Urinary cotinine was extracted with chloroform and the mean recovery of cotinine added to nonsmokers urine was 81 ± 10 (SEM) percent. The intra‐assay and the inter‐assay coefficients of variation were 17% and 28%. Urinary excretion of cotinine was high in habituated smokers before smoking and increased slightly after smoking three cigarettes. There was no correlation between urinary cotinine excretion and pH or urine flow after smoking. Daily urinary excretion of cotinine in smokers tended to relate roughly to daily cigarette consumption although excretion varied even among the smokers who consumed approximately equal numbers of cigarettes. There was no urinary excretion of cotinine in nonsmokers. Successive determinations of the daily cotinine excretion in 7 smokers revealed that the excretion correlated well with cigarette consumption on the corresponding days. We suggest that the measurement of urinary cotinine excretion provides a good index of cigarette smoking.

Ectopic production of human chorionic gonadotropin in malignant tumors

The prevalence of human chorionic gonadotropin (hCG) was estimated by measuring immunoreactive hCG in plasmas and tumor tissues from patients with various neoplasms. To detect small amount of plasma hCG in the presence of luteinizing hormone (LH), plasma hCG level was measured by heterologous radioimmunoassay using anti‐hCG‐β antiserum and compared with plasma LH level measured by heterologous radioimmunoassay using anti‐LH‐β antiserum. All 56 samples obtained from control subjects were found to be negative for hCG, while 10 of 100 plasma samples from patients with malignancies were positive for hCG. The prevalence of hCG in 64 tumor tissues was 42% (27/64); it was 32% (8/25) in so‐called amine precursor uptake and decarboxylation (APUD) tumors and 49% (19/39) in non‐APUD tumors. The difference in the prevalence of hCG in APUD vs. non‐APUD tumors was not statistically significant. However, the amounts of hCG in APUD tumors were found to be less than 50 ng/g wet tissue, whereas those of non‐APUD tumors ranged from several ng to thousands of ng/g wet tissue. These results suggest the APUD tumors produce less amounts of hCG than do non‐APUD tumors. Cancer 42:2328–2333, 1978.

Qualitative and quantitative analyses of human chorionic gonadotropin and its subunits produced by malignant tumors

Human chorionic gonadotropin (hCG) and its subunits in plasma, urine, ascites, and tumor extracts from four patients with hCG‐producing tumors (undifferentiated cell carcinoma and choriocarcinoma of the bladder, malignant teratoma of the retroperitoneum, and pancreatic carcinoma) were measured by the radioimmunoassays specific to each component. While both free α and β subunits as well as the whole molecule of hCG were found in all these samples, the proportion of β subunit was much higher in these tumor extracts than in the placental extracts. Since the α and β subunits are known to be translated from separate mRNAs, such increase of subunit is probably due to the predominant increase of mRNA encoding β subunit of hCG in the hCG‐producing tumors. Gel filtration of the extracts of these four tumors on Sephadex G‐100 and G‐150 columns demonstrated a heterogeneity of hCG, α, and β subunits in these tumor extracts, and the elution profiles of plasma, urine and tumor extracts were slightly different. Lower molecular weight forms of hCG and its β subunit were present in all urine samples. The significance of these heterogeneities remains to be elucidated.

Somatostatin release from isolated perfused rat stomach.

Abstract Gastric somatostatin release from the isolated rat stomach was studied using a perfusion technique. Somatostatin released from the isolated perfused rat stomach was found to be identical in molecular size and immunoreactively with synthetic somatostatin. Infusion of glucagon (10−7 M) caused biphasic increase of gastric somatostatin release. Gastric somatostatin release was also stimulated by infusion of theophylline (10−3 M) and dibutyryl cyclic AMP (10−3 M). These results indicate the possible involvement of adenylate cyclase-cyclic AMP system in the regulatory mechanism of gastric somatostatin release.

Gastric carcinoid with ectopic production of ACTH and β‐MSH

A 51‐year‐old woman with typical Cushings syndrome of about 9 years duration was shown to have a gastric carcinoid tumor. Plasma levels of ACTH and cortisol were elevated and lacked the normal diurnal rhythm. Urinary excretion of steroids was unaffected by the administration of either metyrapone or dexamethasone. Fluctuation in urinary steroid excretion, as well as transient hypokalemic alkalosis and glycosuria suggested periodic hormonogenesis. The extirpated gastric carcinoid was shown to contain immunoreactive ACTH and β‐MSH. However, the biologic ACTH activity was undetectable by in vivo steroidogenic assay. By gel filtration, it was demonstrated that both tumor and plasma ACTH was predominately “big” ACTH. Although postoperatively she developed hypoadrenocorticism severe enough to require ACTH treatment, her pituitary‐adrenal function was gradually restored. This is the first documented case of ectopic ACTH syndrome caused by gastric carcinoid in which successful cure was achieved by surgery.

Multiple-hormone producing lung carcinoma

Endocrine and immunohistochemical studies were performed in a patient with lung cancer associated with gynecomastia. Elevated level of human chorionic gonadotropin (hCG) in plasma and mild hyperadrenocorticism were demonstrated by hormone assays. Postmortem examination proved the existence of anaplastic small cell carcinoma of the lung mixed with a feature of chorioepithelioma. The presence of significant amounts of adrenocorticotropic hormone (ACTH), β‐melanocyte stimulating hormone (β‐MSH), calcitonin, gastrin, hCG, hCG‐α, hCG‐β and human chorionic somatomammotropin (hCS) in tumor tissues was demonstrated by radioimmunoassays, bioassay and immunohistochemical techniques. We present here a unique case of multiple hormones producing tumor elaborating both hormones of amine precursor uptake and decarboxylation (APUD) series (ACTH, β‐MSH, calcitonin and gastrin) and of placentral origin (hCG, hCG‐α, hCG‐β and hCS).

Hypogastrinemia in hypothyroidism.

Fasting plasma gastrin levels measured by radioimmunoassay were found to be low in patients with hypothyroidism. The intravenous injection of arginine caused an increase of plasma gastrin in hypothyroid patients but was significantly lower than those in normal subjects. The decreased gastrin level in patients with hypothyroidism was significantly improved after the thyroid function was normalized by treatment.

Somatostatin release from isolated perfused rat pancreas. Possible role of endogenous somatostatin on insulin release

In order to elucidate the role of endogenous somatostatin in the control of insulin and glucagon secretion, glucagon- or insulin-induced somatostatin release from the isolated perfused rat pancreas was studied. Immunoreactive somatostatin was persistently released for 60 min in response to perfusion by 5.5 mM glucose at concentrations ranging between 10 and 15 pg/ml. The addition of glucagon (10−8, 10−7, and 10−6 M) caused a dose-related increase of somatostatin release. In contrast, insulin release, especially its first phase, was suppressed when concentrations of glucagon were increased. The addition of insulin (10−7 M and 10−6 M) had no significant effect on somatostatin and glucagon release. These results raise the possibility that endogenous somatostatin and glucagon together regulate insulin secretion, suggesting a close interrelationship between insulin, glucagon, and somatostatin secretion within the iSlet.

Radioimmunoassay of nicotine

Abstract A sensitive and specific radioimmunoassay of nicotine was developed using antisera raised against 6-(p-aminobenzamido) nicotine coupled to bovine serum albumin. Inhibition studies with various nicotine analogues revealed that the antisera are highly specific for both the N-methylpyrrolidine ring and the pyridine ring of nicotine, and especially for the structural changes of the former. The use of these antisera in an assay of nicotine in biological fluids is desirable, since the pyrrolidine ring of nicotine is first metabolized in vivo and antibodies must, therefore, discriminate nicotine from other nicotine metabolites.

Effect of pH and urine flow on urinary nicotine excretion after smoking cigarettes

Effects of pH and urine flow on urinary excretion of nicotine were examined in 11 smokers after they had smoked 3 cigarettes during water diuresis. Plasma nicotine showed a slight but nonsignificant rise after smoking. Urinary excretion of nicotine increased significantly from the pre‐smoking levels of 258 ± 76 and 252 ± 147 (mean ± SEM) ng/15 min to the peaks of 2,587 ± 1,224 and 2,561 ± 584 ng/15 min 30 and 45 min after the start of smoking. Thereafter, urinary nicotine tended to decrease and rise with changes in urinary flow. There was a correlation between urinary nicotine and urinary flow after smoking (r = 0.26, p < 0.05). Eleven subjects were grouped based on the mean urinary pH throughout the experiment. No significant amount of nicotine was excreted in the group with pH above 7.5 while groups with pH below 7.4 excreted substantial nicotine after smoking. There was a negative correlation between urinary pH and nicotine excretion (r = −0.58, p < 0.001). Urinary excretion of nicotine cannot be used as an index of smoking unless pH and urine flow are controlled.