Evidence against a role of insulin in hypertension in spontaneously hypertensive rats. CS-045 does not lower blood pressure despite improvement of insulin resistance

Hyperinsulinemia resulting from peripheral insulin resistance has been demonstrated both in spontaneously hypertensive rats (SHR) and in humans with essential hypertension. A new class of antidiabetic drugs, thiazolidinediones, which can improve insulin resistance, may be able to lower not only blood glucose levels but also blood pressure. The present study was therefore designed to clarify the proportion of SHR that are glucose intolerant and to observe the effect on blood pressure of CS-045 (troglitazone) administered at 70 mg/kg per day for 2 weeks to male SHR (n = 13). Among 67 male 8-week-old SHR, 74.6% were glucose intolerant and hyperinsulinemic. Systolic blood pressure did not correlate with plasma glucose or insulin levels before or after glucose loading. Treatment with CS-045 improved insulin resistance, as evidenced by a smaller area under the curve of plasma glucose and insulin levels in response to glucose loading. However, systolic blood pressure was not altered. When the data were reanalyzed according to the presence or absence of glucose intolerance before the treatment, blood pressure in the treated group was the same as in controls despite significant improvement in steady-state plasma glucose levels. These results suggest that hyperinsulinemia and/or insulin resistance may not be involved in the development or maintenance of hypertension in SHR, which is in contrast to models of hypertension such as obese Zucker rats or fructose-fed rats.

Involvement of protein kinase A and C in the production of interleukin-1 alpha-induced prostaglandin E2 from mouse osteoblast-like cell line, MC3T3-E1

Human recombinant interleukin-1 alpha (IL-1) stimulated the mouse osteoblast-like cell line, MC3T3-E1, to produce prostaglandin E2 (PGE2). This was inhibited by 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) in a dose-dependent manner. The protein kinase A (PKA)-specific inhibitor, KT5720, also inhibited the IL-1-induced PGE2 production in MC3T3-E1 cells, as did staurosporine, a potent inhibitor of protein kinase C (PKC). The PKA activator, 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP), weakly stimulated MC3T3-E1 cells to produce PGE2, as did the PKC activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). However, 8-Br-cAMP and TPA acted synergistically to induce PGE2 production equal to that of IL-1. These observations suggest that activation of both PKA and PKC are involved in IL-1-induced PGE2 production in MC3T3-E1 cells.

Felodipine therapy may not alter glucose and lipid metabolism in hypertensives. Felodipine Multicenter Prospective Study Group in Japan

The effects of long-term monotherapy with felodipine, a calcium antagonist, on blood pressure, glucose tolerance, and serum lipid profiles were prospectively investigated in 51 hypertensive patients: 13 with normal glucose tolerance and 38 with glucose intolerance. The levels of plasma glucose, serum lipids, and glycosylated hemoglobin A1c were determined before and during long-term (7.5 +/- 0.5 months; range, 6 to 9 months) therapy with felodipine. A 75-g oral glucose tolerance test was performed before and during long-term felodipine therapy. Significant decreases in both systolic and diastolic blood pressures in both patient groups were maintained during the therapy. Neither fasting nor post-glucose load venous plasma glucose levels were altered in either group of patients, and no patients with normal glucose tolerance developed diabetes mellitus during the study. Serum lipid levels did not change significantly in either group of patients except for significant decreases in high-density lipoprotein cholesterol and apolipoprotein A-I in the group with normal glucose tolerance tests, but those changes remained within the normal range. Furthermore, neither serum lipid nor apolipoprotein levels were altered, even in patients with hypercholesterolemia (total cholesterol levels, > 5.69 mmol/L = 220 mg/dL). These results suggest that long-term therapy with felodipine may not alter glucose and lipid metabolism in hypertensive patients, and felodipine appears to be useful as an antihypertensive agent for hypertensive patients with either dyslipidemia or impaired glucose metabolism.

Effects of captopril or nitrendipine on left ventricular collagen or laminin B2 gene expression

A study was designed to clarify the effects of captopril (CAP) or nitrendipine (NITR) on cardiac hypertrophy and left ventricular expression of the laminin B2 or collagen (COL) gene in spontaneously hypertensive rats (SHRs). Cardiac weight was significantly increased in 20-week-old SHRs. Gene expression of the alpha 1 chain of type IV COL determined by northern blot analysis decreased with age in Wistar-Kyoto rats and SHRs. Left ventricular laminin B2 mRNA was decreased at 12 weeks and increased again at 20 weeks in both strains. Daily oral administration of CAP (40 mg/kg, n = 5) or NITR (30 mg/kg, n = 4) to SHRs from 8 to 20 weeks decreased blood pressure to 142 mmHg (p < 0.01 vs 197 mmHg in controls, n = 5). Cardiac weight was 1.26 +/- 0.04 (SE) g in controls and was reduced to 1.03 +/- 0.05 g (p < 0.01) by CAP, but not by NITR (1.24 +/- 0.04). Left ventricular laminin B2 gene expression was attenuated by CAP and NITR to 41% and 32% of the control value, respectively. CAP significantly decreased left ventricular alpha 1 type IV COL mRNA to 11% of the control level, whereas NITR caused a reduction only to 75%. CAP also decreased alpha 1 or alpha 2 type I COL mRNA. These results suggest that angiotensin converting enzyme inhibitors prevent and/or cause regression of cardiac hypertrophy by inhibiting the gene expression of extracellular matrix, and that angiotensin II may have a pivotal role in cardiac hypertrophy.

[Recent progress in experimental pituitary tumors in various animals]

This article briefly describes the recent progress and opinion on experimental pituitary tumors in various animals. 1) A high incidence of spontaneous pituitary tumor is known in Sprague-Dawley and Wistar rats. 2) Recent studies suggest that the pituitaries of estrogen-treated animals are not tumoral and only hyperplastic. 3) Salmon calcitonin injection for 6 months caused a higher incidence of pituitary hyperplasia or non-functioning adenoma. 4) Mice transgenic by hGRF shows GH-producing hyperplasia or adenoma in the pituitary. 5) Introduction of choleratoxin transgene into mice caused gigantism. 6) Transgenic mice, that develop ACTH-producing pituitary tumor, were generated by PyLT. 7) Mice transgenic for vasopressin-SV 40 hybrid oncogene develop tumors of the endocrine pancreas and the pituitary (as a model of MEN type II).

[Iodination and binding characteristics of 125I-d(CH2)5 [Tyr(Me)2, Tyr(NH2)9] AVP]

With iodinated vasopressin analogue, d(CH2)5[Tyr(Me)2, Tyr(NH2)9] AVP, at position 9, followed by purification by HPLC (specific activity 473-543Ci/mmol), a specific binding was observed in the rat liver plasma membrane fraction. Scatchard analysis indicated a single class of high-affinity binding sites with a Kd of 0.23nM and Bmax of 142fmol/mg protein. V2-agonist, DDAVP, did not displace 125I-vasopressin analogue. These results suggest that 125I-d(CH2)5[Tyr(Me)2, Tyr(NH2)9] AVP with a high specific activity is a useful tool to investigate V1-receptors.

Criteria for differentiating superficial from deep lobe tumours of the parotid gland by computed tomography

A retrospective analysis of the CT images of 36 parotid tumours was undertaken to evaluate the potential value of certain criteria for distinguishing tumours of the superficial lobe from those of deep lobe. The criteria were one of three hypothetical lines indicating the course of the facial nerve, or the course of Stensen's duct. The lines representing the course of the facial nerve are straight lines connecting the main facial nerve trunk with the lateral border of the masseter (line 1), the lateral border of the mandible (line 2) and the retromandibular vein (line 3). Line 1 was significantly more accurate than line 2 or line 3 (P < 0.05); all of superficial (28/28) and 63% of deep lobe tumours (5/8) were correctly diagnosed. On the other hand, when Stensen's duct was used as the criterion, all the superficial (8/8) and deep lobe tumours (3/3) were correctly diagnosed. However, this criterion could be applied only to those cases where both the tumour and Stensen's duct were demonstrated on the same CT-sialogram.

Lipopolysaccharide promoted opening of the porin channel

We show here that the imipenem (a carbapenem, beta-lactam antibiotic)-permeable porin channels (protein D2 or OprD2) of Pseudomonas aeruginosa were closed mostly in the lipopolysaccharide (LPS)-free membrane and were openable by adding LPS to the membrane as assayed by ion conductivity measurements using planar lipid bilayers. Open and closed states of the OprD2 channels exhibited conductivities of about 400 and 30 pS, respectively, in 1 M NaCl. The OprD2 channel in the LPS-containing membrane showed very rapid opening and closing events in a second order and the duration of closure became longer at low membrane potentials.

[The effect of arotinolol on the thyroid function and the autonomic nerve systems]

beta-blockers have been accepted as a reasonable adjunct therapy for the treatment of hyperthyroidism. They lessen the sympathetic symptoms such as tachycardia and finger tremor. On the other hand, many studies have demonstrated a decrease in 3, 3', 5-triiodothyronine (T3) during treatment with beta-blockers (especially propranolol). The purpose of this study is to clarify the effect of arotinolol (alpha 1, beta-blocker) on the thyroid functions and autonomic nerve systems (ANS) of patients with Graves' disease. Arotinolol 20mg a day p.o. was given to untreated patients with Graves' disease (n = 16) for 2 weeks. Blood sampling and the ANS function-tests were done before and after the treatment. In addition, the in vitro effects of arotinolol on the cAMP production and the radioactive iodine uptake (RAIU) using rat thyroid cell line FRTL5 were evaluated to examine the direct influence on thyroid cells. Arotinolol improved hyperthyroid symptoms including tachycardia, but had no effect on ANS function-tests. It is of interest that not only T3 but also T4 decreased after the arotinolol treatment. We therefore suspected the direct suppressive effects of arotinolol on the thyroid. There were, however, no in vitro inhibitory effects on the cAMP production and the RAIU in TSH-stimulated FRTL5 cells. The reason why serum T4 levels in patients with untreated Graves' disease have decreased after the treatment of arotinolol could not be clarified. In conclusion, arotinolol is a very useful drug for the initial therapy of patients with Graves' disease to reduce the serum thyroid hormone levels and symptoms of hyperthyroidism when combined with antithyroid drugs.

The nasal cycle in patients with autonomic nervous disturbance

The nasal cycle is thought to be controlled by the autonomic nervous system. In this study, we measured nasal airflow resistance in patients with lesions of the autonomic nerves that supply the nasal mucosa. We examined 20 patients with facial palsy as examples of parasympathetic disturbance, five with Horner's syndrome as examples of sympathetic disturbance, and one with acute pandysautonomia. The nasal cycle was observed in 13 patients with facial palsy and four patients with Horner's syndrome. The nasal cycle was also observed in one patient with acute pandysautonomia and disturbance of the sympathetic-parasympathetic nerves. Our results indicate that disturbance of the parasympathetic and sympathetic nerves has little influence on the nasal cycle.

Ultrasonic diagnosis of oral and neck malignant lymphoma

A series of 14 patients with nodal and extranodal non-Hodgkin's lymphoma of the oral and neck region was analyzed by ultrasonogram evaluation. Eight nodal lymphomas and six extranodal lymphomas commonly exhibited almost completely similar ultrasonographic findings, specifically, clear delineation of the boundary echo and a homogeneous, weak internal echo, the so-called pseudo-liquid-like images. The results derived from our study suggest that ultrasonic diagnosis is also helpful in evaluating patients with lymphoma during the initial diagnosis and initial treatment like other diagnostic imaging modalities.

Evaluation of the effect of PTCR/PTCA by 99mTc-MIBI myocardial imaging in acute and old myocardial infarction

This study is to clarify the ability of technetium-99m-Hexakis-2-methoxyisobutyl isonitrile(MIBI) myocardial scintigraphy for assessment of the effect of PTCR/PTCA as compared with conventional thallium-201 myocardial scintigraphy (201Tl). 99mTc-MIBI (740-888MBq) was injected before emergency PTCR/PTCA, and the initial imaging was performed immediately after PTCR/PTCA in 4 patients with acute myocardial infarction (AMI). On the other hand, in 2 patients with old myocardial infarction (OMI), 201Tl and MIBI myocardial imagings were performed before and one week after rescue PTCA. The defect area on the follow-up MIBI imaging was smaller than that on the initial MIBI imaging in 2 patients with successful emergency PTCR/PTCA. But in the other 2 AMI patients with unsuccessful reperfusion, the defect area did not significantly decrease after PTCR/PTCA. Reperfusion was successful in one of the two patients with OMI. In both the two patients with OMI, the MIBI defect area did not significantly decrease after rescue PTCA. MIBI myocardial scintigraphy is a useful noninvasive method for evaluating the effect of emergency PTCR/PTCA for myocardial salvage in patients with AMI, because MIBI is a kit type agent, and it does not redistribute.

Incidence of anti-mouse IgG in normal subjects and patients with autoimmune thyroid disease

Serum antibodies to mouse IgG occasionally interfere with two-site immunometric assays in which mouse monoclonal antibodies are used. We examined the titers of antibodies to mouse IgG in serum samples from normal subjects and patients with autoimmune thyroid disease (AITD) using an enzyme-linked immunosorbent assay. Anti-mouse IgG antibodies were positive in 7/119 patients with Graves' disease (5.9%) and 3/60 patients with Hashimoto's thyroiditis (5.0%). One of the 15 patients with a thyroid neoplasm (6.7%) also had antibodies to mouse IgG, as did 5/60 healthy subjects (8.3%). These antibodies were either of the IgG or IgM class. There was no significant difference in the incidence of positive anti-mouse IgG antibody between normal subjects and patients with AITD. It is important to note this high incidence of antibodies to mouse IgG due to the potential of interference with immunometric assays employing mouse monoclonal antibodies.

Computed tomography and ultrasonography in submandibular tumours

The value of computed tomography (CT) and ultrasound (US) for assessing submandibular tumours has been assessed. Thirty-five patients with 23 benign submandibular gland tumours and 12 malignant tumours have been investigated. In 33/35 patients, 18 plain CT (PCT), 19 CT sialography (CTS), and eight intravenous contrast-enhanced CT (CECT) procedures were performed. PCT did not allow clear delineation of 78% of the lesions, due to the similar density of the tumour and normal submandibular gland parenchyma. The tumours were easily recognized as low-echogenic or low-density masses by US, CTS and CECT. Benign lesions were usually sharply demarcated and had smooth borders on US, CTS and CECT. In addition, lobulation was often recognized in pleomorphic adenomas. Malignant tumours were poorly defined with irregular borders in 11/12 cases on US, CTS and CECT. CECT was superior to PCT and CTS in providing images of the tumour and its involvement of adjacent structures. It was concluded that US is the most useful primary examination method for submandibular tumours, while CECT provides the best evaluation of extension to the surrounding structures and/or adjacent lymph nodes. CTS seems to be unnecessary, if a submandibular tumour can be visualized by US and CECT.

A case of Graves' disease with false hyperthyrotropinemia who developed silent thyroiditis

We encountered a patient who developed silent thyroiditis during the course of Graves' disease. The diagnosis of silent thyroiditis was made on the basis of a low thyroidal 131I uptake, no response to the thyrotropin releasing hormone (TRH) test, and subsequent hypothyroidism despite the presence of high titers of thyrotropin (TSH) receptor antibody (TRAb) and thyroid stimulating antibody (TSAb). The patient, in addition, had a discrepancy between serum TSH and thyroid hormone values. This was due to the presence of interfering substances that react to mouse IgG in the sera since serum TSH levels were decreased in a dose dependent manner by the addition of increasing amounts of mouse IgG to the sera. It should therefore be noted that silent thyroiditis can develop in patients with Graves' disease. Furthermore, clinicians should be aware that two-site immunoassay kits that use mouse monoclonal antibodies are subject to interference by some substances, possibly antibodies which react to mouse IgG.

Disturbance of thyroidal iodine metabolism in BB/W rat

To investigate the thyroid function in Bio-Breeding Worcester (BB/W) rats, we have examined the iodine metabolism, serum TSH and thyroid hormone levels in 8- and 16-week-old BB/W and normal Wistar (W) rats. At 8 weeks of age, serum TSH levels were significantly higher in BB/W rats than in W rats, although there was no difference in the serum levels of free T3 and free T4. Furthermore, the thyroidal radioactive iodine incorporation at 48 h was significantly lower in BB/W rats, suggesting that they might have some defects in iodine organification. At 16 weeks of age, serum TSH levels were also significantly higher in BB/W rats than in W rats. Furthermore, serum TSH levels in 16-week-old BB/W rats were significantly higher than in 8-week-old BB/W rats. The thyroid weight was significantly greater in BB/W rats, probably due to the increased serum TSH. The thyroidal radioactive iodine uptake at 48 h and the iodine content in the thyroid homogenates were significantly lower in BB/W rats. These results suggest that BB/W rats have some defect in iodine metabolism resulting in impaired thyroid hormone synthesis.

Salmon calcitonin induces pituitary tumor in rats

Calcitonin is widely used in the treatment of post-menopausal osteoporosis. The present study was designed to investigate the effects of salmon calcitonin (SCT) on the incidence of the pituitary tumors in Sprague-Dawley (SD) rats. Subcutaneous injections of SCT at a dose of 160 IU/kg/day for 6 months reduced body weight and induced one pituitary hyperplasia and three pituitary adenomas in 4 of 5 animals, while 5 controls did not show any changes. Prolactin-positive cells were located at the periphery of the affected pituitaries adjacent to the prolactin-negative adenomas. In addition, serum concentrations of prolactin and TSH were lower than in the controls, although serum calcium or LH levels were not significantly different from the controls. Among 7 animals treated with SCT for 6 months followed by no medication for another 6 months, 5 adenomas were detected, one of which had invasive growth toward the adjacent tissue, whereas only one adenoma was found in 9 controls. These results suggest that SCT administration at a high dose may induce the formation of pituitary adenoma, or may accelerate the development of spontaneous pituitary adenomas, some of which show frequent mitotic figures and invasive growth into the surrounding tissue, possibly resulting in malignant transformation. This indicates the need for caution in considering whether calcitonin injections into patients with osteoporosis as well as Paget's disease may induce such pituitary tumors.

Effects of PGE1 on the development of diabetes and surface markers of lymphocytes in BB/W/Tky rats

To study the effect of an oral prostaglandin E1 (PGE1) derivative and/or lipo PGE1 on the onset of diabetes, these agents were administered to Bio-Breeding/Worcester/Tokyo (BB/W/Tky) rats from 4 to 13 weeks of age. Lymphocyte subsets in peripheral blood from normal Wistar and BB/W/Tky rats were measured before and for one week after administration of PGE1 using laser flow cytometry. Results showed that 14/16 (87.5%) of the BB/W/Tky rats administered PGE1 developed diabetes vs. 6/12 (50%) in the control BB/W/Tky rats. In normal Wistar rats, PGE1 significantly increased the W3/25+OX39+ and OX8+OX39+ cells. In BB/W/Tky rats, PGE1 significantly increased the OX19+OX6+, OX19+OX39+, W3/25+OX6+, W3/25+OX39+, OX8+, OX8+OX6+, OX8+OX39+ and OX39+ cells, while decreasing the OX6+ cells. We conclude that the administration of PGE1 to BB/W/Tky rats accelerates the development of spontaneous diabetes and alters the surface markers of lymphocytes.

Effects of arginine vasopressin on blood pressure and renal prostaglandin E2 in rabbits

The role of arginine vasopressin (AVP) in blood pressure regulation in humans and animals is still controversial. The present study was designed to investigate the effects of AVP on blood pressure and the excretion of sodium and prostaglandin (PG) E2 in rabbits. AVP dissolved in 0.01 M acetic acid was infused subcutaneously at a rate of 0.86 ng/kg/min with a miniosmotic pump into 12 New Zealand white rabbits (2.7-3.4 kg), while 10 controls were given vehicle alone. AVP infusion resulted in a 3.5-fold rise in the level of plasma AVP (21.8 +/- 4.4 (SEM) pg/ml) as compared with controls, associated with a significant decrease in the urine volume and urinary excretion of sodium. The PGE2 excretion was increased 1.8-fold after AVP infusion. In the chronic AVP-infused group, blood pressure was not significantly increased, but the acute vascular response to AVP was significantly attenuated without any changes in the vasopressor response to angiotensin II. Preadministration of V1-antagonist completely abolished the vasopressor action of AVP, but not that of angiotensin II, in either group. These results suggest that circulating AVP within physiological range of concentrations may stimulate renal PGE2 synthesis and attenuate the vascular response through vascular V1 receptors without affecting the baroreflex, which may be attenuated through V2 receptors.

Blood ketone bodies in NIDDM: relationship with diabetic control and endogenous insulin secretion

To evaluate the relationship of blood ketone bodies with diabetic control and endogenous insulin secretion, fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), fasting serum C-peptide (CPR), blood total ketone-bodies (TKB), blood acetoacetate (AcAc) and blood 3-hydroxybutyrate (3-OHB) were compared in 78 outpatients with non-insulin-dependent diabetes mellitus (NIDDM) treated with diet (n = 13), sulfonylurea (n = 52) and insulin (n = 13). TKB, AcAc and 3-OHB in patients treated with insulin were significantly higher than in patients treated with diet or sulfonylurea. In patients given diet therapy, log 3-OHB showed significant negative correlations with FPG, HbA1c and CPR. In patients treated with sulfonylurea, log 3-OHB showed significant positive correlations with FPG and HbA1c, but not with CPR. In patients treated with insulin, there were no correlations of log 3-OHB with FPG, HbA1c and CPR. For evaluation of the metabolic state in diabetes mellitus, measurement of blood ketone bodies is useful, and moreover necessary, in addition to diabetic control or determination of the endogenous insulin level.