Reduced beta-cell glucose transporter in new onset diabetic BB rats.

Previous studies from our laboratories have suggested a defect in glucose transport in islets isolated from BB rats on the first day of overt diabetes. To quantitate by immunostaining the glucose transporter of beta-cells (GLUT-2) before and at the onset of autoimmune diabetes we employed an antibody to its COOH-terminal octapeptide. On the first day of overt diabetes, defined as the day the daily blood glucose first reached 200 mg/dl, the volume density ratio of GLUT-2-positive to insulin-positive beta-cells was only 0.48 +/- 0.06, compared to 0.91 +/- 0.02 in age-matched nondiabetic diabetes-resistant controls (P less than 0.001). In age-matched nondiabetic diabetes-prone rats, most of which would have become diabetic, the ratio was 0.85 +/- 0.02, also less than the controls (P less than 0.05). Protein A-gold labeling of GLUT-2 in beta-cells of day 1 diabetic rats revealed 2.17 +/- 0.16 gold particles per micrometer length of microvillar plasma membranes compared to 3.91 +/- 0.14 in controls (P less than 0.001) and 2.87 +/- 0.24 in the nondiabetic diabetes-prone rats (P less than 0.02). Reduction in GLUT-2 correlates temporally with and may contribute to the loss of glucose-stimulated insulin secretion that precedes profound beta-cell depletion of autoimmune diabetes.

Effects of hypoglycemia and prolonged fasting on insulin and glucagon gene expression. Studies with in situ hybridization.

In situ hybridization of proinsulin and proglucagon mRNA was performed in rat pancreas to assess prohormone gene expression during various glucopenic conditions. During a 4-d fast mean blood glucose declined by 48 mg/dl; proinsulin mRNA signal density remained normal while proglucagon mRNA signal density more than doubled. At the end of a continuous 12-d insulin infusion blood glucose averaged 53 +/- 12 mg/dl; proinsulin mRNA signal density declined to 30% of controls while proglucagon mRNA signal density more than doubled. In insulinoma-bearing NEDH rats blood glucose averaged 34 +/- 3.5 mg/dl; the proinsulin mRNA signal was virtually undetectable and proglucagon mRNA signal density was more than twice the controls. There was no detectable change in either beta-cell area or islet number in rats subjected to fasting or insulin infusion, but in insulinoma-bearing rats beta cell area was markedly reduced. Thus compensation during 4 d of starvation involves an increase in glucagon gene expression without change in insulin gene expression or beta cell mass. In moderate insulin-induced hypoglycemia glucagon gene expression is increased and insulin gene expression decreased. In more profound insulinoma-induced hypoglycemia, in addition to the foregoing changes in hormone gene expression, there is a profound reduction in the number of insulin-expressing cells.

Cytoplasmic pH in cultured porcine thyroid cells: alkalinization by epidermal growth factor.

We studied the effects of epidermal growth factor (EGF), thyroid-stimulating hormone (TSH) and amiloride on cytoplasmic pH (pHi) in cultured porcine thyroid cells. We used 2',7'-bis(2-carboxyethyl)-5- (and 6-)carboxyfluorescein (BCECF), an internalized fluorescent pH indicator, to measure pHi. EGF stimulated thyroid cell alkalinization and proliferation, which were blocked by amiloride. EGF-stimulated thyroid cell alkalinization depended on extracellular Na+ concentrations. EGF stimulation resulted in an activation of Na+/H+ exchange, which alkalinized the cells. The results indicated that Na+/H+ exchange or cell alkalinization might function as a transmembrane signal transducer in the action of EGF. In the present system, TSH did not stimulate alkalinization or proliferation.

Streptozocin- and alloxan-induced H2O2 generation and DNA fragmentation in pancreatic islets. H2O2 as mediator for DNA fragmentation.

Streptozocin (STZ) and alloxan (ALX) exhibit the most potent diabetogenicity and are used for induction of experimental diabetes mellitus. An understanding of the mechanisms of action of the typical diabetogenic agents is important for elucidating the causes of diabetes. Okamoto proposed a model in which DNA fragmentation plays an important role in the development of diabetes. DNA fragmentation supposedly results from the accumulation of superoxide or hydroxyl radicals. However, direct evidence for this accumulation is lacking. With isolated rat pancreatic islets in vitro, we demonstrated that STZ and ALX stimulated H2O2 generation and caused DNA fragmentation. Addition of STZ or ALX resulted in an increase in H2O2 generation. On DNA analysis, when incubated without STZ or ALX, DNA sedimented as a single peak; when incubated with STZ or ALX, DNA sedimented slower as a broad peak and was fragmented. Graded doses of STZ and ALX stimulated H2O2 generation and induced DNA fragmentation; their effects on H2O2 generation and DNA fragmentation were evident at a concentration of 0.1 mM and were maximal at 1 mM. Administration of STX or ALX to rats in vivo stimulated H2O2 generation and caused DNA fragmentation in pancreatic islets. H2O2 itself also induced DNA fragmentation. These findings may support Okamoto's proposal that STZ and ALX induce diabetes through the following biochemical events: STZ and ALX----H2O2 generation----DNA fragmentation----beta-cell destruction. This study may constitute the first demonstration of STZ- and ALX-stimulated H2O2 generation, which probably acts as a mediator of STZ- and ALX-induced DNA fragmentation.

A screening test to identify aldosterone-producing adenoma by measuring plasma renin activity. Results in hypertensive patients.

In an attempt to devise a screening test for aldosterone-producing adenoma (APA) among hypertensive patients, the serum sodium and potassium levels, plasma renin activity (PRA), plasma aldosterone concentration, and aldosterone-PRA ratio were measured in 348 patients with hypertension. Nine patients with a substantially elevated aldosterone-PRA ratio were selected and hospitalized for further investigations. All nine patients were then recognized by scintigraphy with labeled cholesterol, venography, and surgical excision as having APA. The serum concentration of potassium was subnormal in three of nine patients with APA. In patients with APA, administration of diuretics and salt restriction significantly elevated PRA. However, even under notable diurnal and day-to-day variations of plasma aldosterone concentrations, the aldosterone-PRA ratio was always elevated inappropriately (more than 400) in patients with APA. In contrast, after administration of diuretics, both the PRA and aldosterone levels increased significantly in patients with essential hypertension, but the aldosterone-PRA ratio was less than 200. Since the renin-angiotensin system seems to be a major factor controlling aldosterone secretion in normal subjects, it is suggested that an elevation of aldosterone-PRA ratio more than 400 is a useful screening tool for the prediction of APA among hypertensive patients.

Effects of antithyroid drug therapy on blood glucose, serum insulin, and insulin binding to red blood cells in hyperthyroid patients of different ages.

The mechanism of glucose intolerance in thyrotoxicosis was investigated in 119 patients with Graves's disease with careful consideration of the age-related deterioration of glucose tolerance. Before and after treatment of thyrotoxicosis with antithyroid drug, changes of blood glucose (BG) and serum immunoreactive insulin (IRI) in response to 50 g oral glucose tolerance test (OGTT) and insulin binding to red blood cell (RBC) were evaluated. In control subjects, the sigma IRI/sigma BG ratio after 50-g OGTT decreased progressively with age without significant change in absolute sigma IRI value, suggesting the occurrence of age-related insulin resistance. Glucose intolerance was much more apparent in hyperthyroid patients because of age-related relative decrease of insulin secretion. Such a decrease of insulin secretion was not found in age-matched postgastrectomy patients with a similar degree of hyperglycemia, however. Maximal binding of labeled insulin and number of insulin receptors of RBC were decreased in old patients but binding affinity was unchanged. Elevation of BG was partially suppressed when serum thyroxine (T4) and triiodothyronine (T3) were reduced to moderately supernormal levels, whereas sigma BG, sigma IRI, sigma IRI/sigma BG ratio, and insulin binding to RBC were all returned to normal when normal serum thyroid hormone concentration was maintained. Our data indicate that insufficient insulin secretion and reduced insulin action at the target cell are responsible, at least in large part, for age-related glucose intolerance in hyperthyroid patients.

Association of CTLA-4 gene A/G polymorphism in Japanese type 1 diabetic patients with younger age of onset and autoimmune thyroid disease.

OBJECTIVE: We studied the association between type 1 diabetes with autoimmune thyroid disease (AITD) and A/G allele polymorphism in exon 1 of the CTLA-4 gene in a Japanese population. RESEARCH DESIGN AND METHODS: We studied 74 Japanese type 1 diabetic patients with or without AITD and 107 normal subjects to identify the association between CTLA-4 polymorphism and type 1 diabetes using polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: The frequency of the CTLA-4 G allele differed significantly between the type 1 diabetic patients (61%) and the normal control subjects (48%) (P = 0.016). The difference in the CTLA-4 G allele became greater between patients with a younger age of onset of type 1 diabetes (age at onset <30 years) and the normal control subjects (64% and 48%, respectively). However, the frequency of the CTLA-4 G allele did not differ between type 1 diabetic patients with younger and older age of onset (64% vs. 57%). The G allele frequencies in the patients with younger-onset type 1 diabetes and AITD increased more than in the control patients (P = 0.025). These differences reflected a significant increase in the frequency of G/G genotype--that is, 54% in those with younger-onset type 1 diabetes and AITD, 39% in those without AITD, and 28% in control subjects. CONCLUSIONS: An association was detected between the CTLA-4 gene polymorphism and younger-onset type 1 diabetes with AITD. The G variant was suggested to be genetically linked to AITD-associated type 1 diabetes of younger onset in this apanese population. The defect in these patients presumably lies in a T-cell-mediated autoimmune mechanism.

In vitro and in vivo effects of MDP-Lys(L18) on mouse megakaryocyte progenitor cells (CFU-Meg).

We investigated the in vitro and in vivo effects of MDP-Lys(L18), a derivative of muramyl dipeptide (MDP), on megakaryocyte progenitor cells (megakaryocyte colony-forming units, CFU-Meg) in the mouse bone marrow and spleen. When CFU-Meg culture was performed with a suboptimum concentration (2%) of pokeweed mitogen-stimulated mouse spleen-conditioned medium (PWM-SCM), addition of 0.1-20 micrograms/ml of MDP-Lys(L18) increased the number of megakaryocyte colonies. The size of the megakaryocyte colonies (the number of megakaryocytes per colony) was also significantly increased by the addition of MDP-Lys(L18) under the same culture conditions in comparison with cultures without MDP-Lys(L18). MDP-Lys(L18) itself did not stimulate megakaryocyte colony formation without PWM-SCM, and it failed to enhance megakaryocyte colony formation in cultures with an optimum PWM-SCM concentration (10%). Furthermore, no effect of MDP-Lys(L18) was observed in cultures of phagocytic cell-depleted bone marrow cells. However, MDP-Lys(L18) enhanced megakaryocyte colony formation in cultures of T-lymphocyte-depleted bone marrow cells. The culture supernatant from a macrophage cell line, J774.1, plus MDP-Lys(L18) enhanced in vitro megakaryocyte colony formation in cultures with a suboptimum PWM-SCM concentration. Although interleukin 1 (IL-1)beta in the culture supernatant of J774.1 plus MDP-Lys(L18) was increased in a dose-dependent manner in response to MDP-Lys(L18), the effect of the culture supernatant was not blocked by an anti-IL-1 antibody, and IL-1 beta failed to enhance megakaryocyte colony formation in the presence of suboptimum PWM-SCM levels. The enhancement of megakaryocyte colony formation by MDP-Lys(L18) could be neutralized, however, by an anti-interleukin 6 (IL-6) antibody. Intraperitoneal administration of MDP-Lys(L18) (100 micrograms daily for 3 days) significantly increased the number of bone marrow and spleen megakaryocyte colonies at 24 to 72 h after the final injection. These in vitro and in vivo observations strongly suggest that MDP-Lys(L18) indirectly enhances the proliferation and differentiation of mouse CFU-Meg via colony-stimulating factor(s) other than IL-1, probably as a result of the stimulation of macrophages to produce IL-6.

Requirements of follicle structure for thyroid hormone synthesis; cytoskeletons and iodine metabolism in polarized monolayer cells on collagen gel and in double layered, follicle-forming cells.

Thyroid cells take up iodine and synthesize thyroid hormones. Thyroid cell polarity plays an important role in the uptake of iodine. However, we do not know whether polarity itself is enough for thyroid hormone synthesis or whether follicle structure is required for it. Using polarized monolayer porcine thyroid cells, cultured on collagen-coated filters, and double layered, follicle-forming cells, we analyzed the relationships of iodine metabolism and cell polarity (and follicle formation). We demonstrated that follicle structure was required for thyroid hormone synthesis. A quick-freezing and deep-etching method revealed the three-dimensional ultrastructures of cytoskeletons in the thyroid cells. On the collagen gel, the thyroid cells are reorganized into polarized monolayer cells; the basal cell membranes are in contact with the collagen gel and the apical ones face the culture medium. Actin microfilaments predominate under the apical cell membranes and intermediate filaments in the basal cytoplasm. The arrangement of these cytoskeletons determines the polarity of the cells. When the cells are cultured as double layers, follicle structures are reconstructed between the two monolayers. When apical cell membranes are in contact with other apical ones or when the cells are cultured as double layers, the cells are reorganized into follicles; the basal cell membranes are in contact with the collagen gel, and the apical ones face the follicle cavities. Actin microfilaments predominate at the apical cell membranes and intermediate filaments in the basal cytoplasm. Polarized thyroid cells transport iodine from the basal compartments to the apical ones, but cannot organify iodine into thyroid hormones. However, follicle-forming cells, cultured as double layers, take up iodine and organify it into thyroid hormones. Polarity is important for iodine uptake, and follicle structure is required for thyroid hormone synthesis.

Thyrotropin-induced acceleration of calcium efflux from mouse thyroid: evidence for inhibition by excess iodide.

We investigated the effect of TSH on calcium transport in mouse thyroid, as well as the influence of iodide thereupon. Thyroid lobes were incubated in Krebs-Ringer bicarbonate buffer containing [45Ca2+] and the time-dependent uptake of [45Ca2+] by the lobes was observed. In the presence of 0.5 mU/ml TSH, the uptake of [45Ca2+] was significantly depressed at early phases of incubation (from 20 to 40 min). Similarly, (Bu)2cAMP (DBC) depressed the [45Ca2+] uptake. The efflux of calcium was also studied by using thyroid lobes preloaded with [45Ca2+]. In the presence of 0.5 mU/ml TSH, [45Ca2+] release from the lobes was doubled in comparison with the control lobes incubated without TSH. DBC similarly accelerated [45Ca2+] release from the lobes. The acute administration of excess iodide to mice fed a low iodine diet inhibits the TSH-induced adenylate cyclase activation in thyroids. The acceleration of calcium efflux induced by TSH was completely abolished by the acute administration of excess iodide in thyroids obtained from animals fed a low iodine diet. Similarly, DBC-induced acceleration of calcium efflux was inhibited by pretreatment with excess iodide. However, the inhibitory effect of iodide on TSH- or DBC-induced acceleration of calcium efflux was not observed in thyroids obtained from mice fed a regular diet. Inhibition of TSH-induced acceleration of calcium efflux by iodide was diminished by treatment of mice with methimazole before iodide. These results suggest that 1) TSH accelerates calcium efflux from the thyroid as a result of accumulation of cAMP in the thyroid, and that 2) iodide inhibits calcium efflux by inhibition of TSH-induced adenylate cyclase activation and by inhibition of the mechanism(s) which is (are) activated by cAMP.

Increased sensitivity of the thyrotroph to thyrotropin-releasing hormones in rats with hypothalamic hypothyroidism.

The status of TSH secretion in hypothalamic hypothyroidism was evaluated by using rats with anterior medial basal hypothalamic deafferentation as the experimental model of the disorder. In the deafferented rats, the basal serum thyroid hormone concentrations as well as that of TSH was significantly lower than normal and cold exposure failed to increase serum TSH, indicating they were in fact in a hypothalamic hypothyroid state. The minimum effective dose of TRH to elicit an increase in serum TSH was smaller in the deafferented rats than in the controls, whereas the response to the maximum dose of TRH was similar in both groups. Although the radioimmunoassayable TSH of the adenohypophysis was significantly decreased in the deafferented rats, it was qualitatively similar to that of the control rats, since the peak of TSH immunoreactivity was eluted at exactly the same position on the gel filtration column in the pituitaries from normal and deafferented rats. When the adenohypophysis was perifused in vitro with Krebs-Ringer solution buffered with Hepes, the minimum effective dose of TRH was similar in both cases. This finding suggests that the exposure to the perifusion medium completely devoid of thyroid and hypothalamic hormones erased the difference in sensitivity to TRH between the two groups as observed in vivo, although in vivo experiments on deafferented rats with normal thyroid hormone induced by exogenous thyroid hormone were not performed. Our results indicate that in hypothalamic hypothyroid rats: 1) the sensitivity but not the responsiveness of the thyrotroph to TRH is increased; and 2) the readily releasable fraction of pituitary TSH pool in response to exogenous TRH is increased. It is also suggested that the difference in the milieu between the pituitary of normal and deafferented rats in vivo is critically important for the latter to retain hypersensitivity to TRH.

An elevation of serum immunoglobulin E provides a new aspect of hyperthyroid Graves' disease.

In hyperthyroid Graves' disease, short-term methimazole is sufficient to induce lasting remission in some patients, but even long-term treatment fails to do so in others. We have evaluated the role of autoimmune abnormalities in the helper T cell type 2 (TH2)-interleukin-13 (IL-13)-TSH receptor system in maintaining hyperthyroidism by comparing IgE levels in patients with various thyroid diseases. One hundred and ninety-three patients with hyperthyroid Graves' disease were treated with methimazole, and blood samples were obtained to measure serum levels of T4, T3, TSH, thyroglobulin, antimicrosomal antibody, TSH binding inhibitory Ig (TBII), thyroid-stimulating antibody, thyroid stimulation-blocking antibody, IgE, interferon-gamma, IL-4, and IL-13. Elevation of serum IgE (> or = 170 U/mL) was found in 35.5% of patients with hyperthyroid Graves' disease, and serum levels of T4, T:1, antimicrosomal antibody, and TBII were significantly greater in patients with IgE elevation than in those with normal serum IgE. During methimazole treatment, there was a parallel decrease in the serum T4 concentration in the presence or absence of an IgE elevation. However, there was a significantly smaller decrease in TBII in patients with elevated IgE than in those with normal IgE. As a result, the remission rate was significantly greater in patients with normal IgE than in those with IgE elevation. Serum levels of IL-13 were elevated in 64.7% of patients with IgE elevation in the absence of detectable TH1 marker, interferon-gamma. These findings suggest that in one third of patients with hyperthyroid Graves' disease, TH2 cells are stimulated and secrete excess amounts of IL-13, which subsequently stimulates B cells to synthesize more TSH receptor antibody and IgE, so that during methimazole treatment TBII decreases less in patients with IgE elevation, producing a lower remission rate.

Effect of thyrotropin-releasing hormone on serum thyroid hormones: a study in the patients with untreated and treated Graves' disease and subacute thyroiditis.

In order to investigate the extrapituitary action of TRH on the thyroid, serum T3, T4, and TSH levels after im administration of TRH were analyzed in 63 patients with untreated hyperthyroid Graves' disease, in 60 euthyroid patients with treated Graves' disease, in 8 patients with subacute thyroiditis, and in 140 healthy subjects. TRH administration in the healthy subjects resulted in a significant increase in serum T3 and T4 levels after 2 h. However, in the patients with untreated hyperthyroid Graves' disease, a significant decrease in serum T3 and T4 levels with undetectable TSH was found 2 h after TRH administration. In the patients with subacute thyroiditis, serum T3 levels also significantly decreased after TRH administration. When a decrease in serum T3 and T4 levels after TRH administration in the patients with hyperthyroid Graves' disease was analyzed in terms of thyroid microsomal antibody and thyroglobulin antibody, a decrease in serum T3 and T4 levels was largest in patients with thyroid microsomal antibody and thyroglobulin antibody. In contrast, an increase in serum T3 and T4 levels in response to TRH in the euthyroid patients with Graves' disease was largest in patients without thyroid autoantibodies. It is concluded that TRH acts directly on the thyroid to suppress the thyroid hormone secreting activity in the absence of circulating TSH and that thyroid autoantibodies affect thyroidal response after TRH administration.

Seventeen alpha-hydroxylase deficiency with one base pair deletion of the cytochrome P450c17 (CYP17) gene.

Mutation of the cytochrome P450c17 (CYP17) gene causes 17 alpha-hydroxylase deficiency (17OHD). Recently, several researchers have elucidated the molecular basis of 17OHD by gene analysis. We experienced a case of 17OHD and intended to reveal the abnormality of the CYP17 gene in this Japanese female with 17OHD. Leukocytes were obtained from the patient, her mother and sister, and normal control subjects. We amplified the CYP17 gene using polymerase chain reaction and performed the sequence analysis using the dideoxy terminator method and restriction enzyme analysis. We found that the patient had one base-pair deletion at the position of amino acid 438. An identical result was obtained with restriction enzyme analysis. This G deletion altered the reading frame and resulted in a premature stop codon at position 443; the ligand of heme iron (Cys: cystine 442) was absent. This small mutation may account for the patient's clinical manifestations of 17OHD. This is the first case of 17OHD with only one base pair deletion of the CYP17 gene.

Remission and recurrence of hyperthyroid Graves' disease during and after methimazole treatment when assessed by IgE and interleukin 13.

We analyzed the relationship between serum IgE concentrations and the remission or recurrence of Graves' disease. One hundred seven patients with Graves' disease were treated with methimazole (MMI). Serum IgE concentration greater than 170 IU/ml was found in 41 of 107 untreated patients (38.3%). However, the presence of TSH-binding inhibiting immunoglobulin or thyroid-stimulating antibody did not correlate with the IgE concentrations. Remission was found in 20 of 41 patients with elevated IgE concentrations (48.8%) after 18 months of MMI treatment, as opposed to 53 of 66 patients with normal concentrations (80.3%) (P = 0.0014). MMI treatment was discontinued in 73 patients who were followed for 26-48 months. The recurrence of Graves' disease was found in 13 patients, whereas the remaining 60 were still in remission. The rate of long-standing remission was lower in patients with elevated than normal IgE concentration (34.1% vs. 69.7%, P = 0.0007). We also analyzed serum levels of interleukin (IL)-13. Although IL-13 was not detected in all patients, the detection rate was higher in patients without remission and in those with recurrence than in those with long-standing remission (47.1%, 38.5%, and 13.3%, respectively; P = 0.0012). More patients with elevated IgE were positive for allergic diseases and for family history of allergic diseases in their first-degree relatives. We conclude that the elevation of IgE and the higher detection rate of IL-13 are associated with both remission and recurrence of Graves' disease.

Inhibitory action of thyrotropin-releasing hormone on serum amylase activity and its mechanism.

The effect of im administration of 500 micrograms TRH on serum amylase activity was studied in 34 normal women, 6 women with primary hypothyroidism, 1 woman with anorexia nervosa, 6 women with hyperthyroidism due to Graves' disease, and 5 women with renal failure on chronic hemodialysis. Serum amylase activity decreased significantly in 31 of 34 normal subjects 60 to 120 min after administration of TRH. However, amylase isoenzymes were not significantly affected after administration of TRH, suggesting that TRH equally affects pancreatic and salivary amylase activity. TRH was also effective in patients on chronic hemodialysis, indicating that TRH does not reduce serum amylase activity by increasing urinary excretion of amylase. Since TRH reduced serum amylase activity in hyperthyroid patients in whom TRH failed to stimulate TSH secretion, TRH does not reduce serum amylase activity through increased secretion of TSH. The action of TRH was not mediated by serum thyroid hormone levels since TRH was similarly effective in patients with hypothyroidism or hyperthyroidism. TRH did not inhibit or interfere with amylase determination when added in vitro to heparinized blood. Perfusion of the dog pancreas with TRH reduced amylase activity in pancreatic juice and pancreatic venous blood. The magnitude of the decrease was related to the dose of TRH used. Since decrease in amylase activity of the pancreatic juice preceded that in pancreatic venous blood, TRH probably directly acts on the pancreas to reduce amylase secretion. As a result, serum amylase activity decreased after administration of TRH.

Black (or brown) adrenal cortical adenoma: its characteristic features on computed tomography and endocrine data.

Seventeen patients with adrenal adenoma causing Cushing's syndrome, eight patients with Cushing's disease due to hypersecretion of ACTH, and five patients with primary aldosteronism due to an aldosteronoma were studied for their computed tomographic (CT) patterns, hormonal profiles, and macroscopic and microscopic findings of the adrenal gland. Black (or brown) adrenal adenomas were found in 71% of the patients with Cushing's syndrome, but not in patients with aldosteronoma. The adrenal tissue of patients with Cushing's disease was predominantly yellow. The number of compact cells was larger in black or brown adenomas than in yellow tumors or hyperplastic adrenal tissue. In patients with Cushing's syndrome, urinary excretion of 17-ketosteroids (17-KS) and serum aldosterone concentrations were lower in those with black or brown adenomas than in those with yellow adenomas (P less than 0.05). Patients with Cushing's disease had even higher 17-KS and serum aldosterone levels. No difference was found in serum cortisol concentrations and dexamethasone suppressibility in two types of adenomas causing Cushing's syndrome. Visual estimation of radiological density of the adrenal tissue relative to the kidney on CT scan and quantitative measurement of it by CT number revealed a difference between the two types of adrenal tumors causing Cushing's syndrome. Adrenal tumors with decreased density on CT scan were yellow adenomas with predominantly clear cells, and those with equal or increased density were black or brown adenomas with predominantly compact cells. All aldosteronomas had decreased density and consisted of clear cells. It is suggested that black or brown adenomas of the adrenal gland have higher radiological density and accompanying lower serum aldosterone and urinary 17-KS levels than ordinary yellow tumors. The abundance of compact cells may have some significance for the development of this particular type of adrenal tumor.

Cytoplasmic pH in cultured porcine thyroid cells: alkalinization by Ca2+.

The role of calcium in cytoplasmic pH (pHi) changes was studied using 2',7'-bis(2-carboxyethyl)-5-(and 6-)carboxyfluorescein, an internalized fluorescent pH indicator, in cultured porcine thyroid cells. The Ca2+ ionophores A23187 and ionomycin stimulated thyroid cell alkalinization. An increase in cytoplasmic free calcium resulted in activation of Na+/H+ exchange which alkalinized the cells.

Concurrent hypersecretion of aldosterone and cortisol from the adrenal cortical adenoma.

Hypertension, hypokalemia, suppressed plasma renin activity and increased plasma aldosterone were found in a middle-aged woman. Following removal of the tumor in the left adrenal gland these abnormalities disappeared. Concurrently, however, the plasma cortisol level did not show normal diurnal change, although the value at 6 A.M. was within the normal range. Administration of 2 mg dexamethasone failed to depress the plasma cortisol level and urinary 17-OHCS concentrations. Postoperatively, plasma cortisol and urinary 17-OHCS were below normal. Histologic examination of the tumor indicated the presence of two types of adenoma cells; one was a large watery clear cell with rich lipid and possibly with aldosterone secretion and the other was an acidophilic cell with poor lipid and possibly with cortisol secretion. It is suggested that, in addition to oversecretion of aldosterone, the tumor autonomously secreted cortisol, although the amount of cortisol secreted was not large enough to produce typical Cushing's syndrome.

An abnormal sodium metabolism in Japanese patients with essential hypertension, judged by serum sodium distribution, renal function and the renin-aldosterone system.

OBJECTIVE: The role of the renin-aldosterone system and the ability of renal sodium reabsorption to facilitate pressure natriuresis were analyzed by using a sufficient number of Japanese patients with essential hypertension. METHODS: We studied 3222 normal Japanese subjects (610 in Kashiwa City Hospital and 2612 in Shinshu University Hospital), 741 Japanese patients with essential hypertension (256 in Kashiwa City Hospital and 485 in Shinshu University Hospital), 20 patients with aldosterone-producing adenomas and 11 patients with idiopathic hyperaldosteronism to determine the possible roles of sodium, renal function, and plasma aldosterone concentration (PAC) on blood pressure elevation. Inappropriate elevation of aldosterone levels [elevation of the aldosterone:plasma renin activity (PRA) ratio] was used to assess aldosterone action. RESULTS: The peak of the serum sodium distribution curve was approximately 2 mmol/l higher in the patients with essential hypertension than it was in controls. The prevalence of higher serum sodium concentrations (> or = 147 mmol/l) also was increased significantly hypertensive patients. Age-related deterioration of renal function did not explain the hypertension and abnormal sodium metabolism in the hypertensive patients. In stepwise regression analysis, the serum sodium concentration was related inversely to the PRA and positively to the PAC:PRA ratio. Although there was an inverse relationship between urinary sodium excretion (representing sodium intake) and the PRA, urinary sodium excretion proved not to be significant as a source of variation in the PAC or in the PAC:PRA ratio in the hypertensive patients. Although the PAC was within the normal range in patients with serum sodium concentrations of 147 mmol/l or more and an elevated PAC:PRA ratio, it was inappropriately high for the stimulus applied, as indicated by the PRA; this is similar to the situation with aldosterone-producing adenomas or idiopathic hyperaldosteronism. CONCLUSION: Serum sodium distribution patterns differed between normal subjects and patients with essential hypertension in this Japanese population. The deterioration of renal function and increased sodium intake did not explain this abnormal sodium metabolism. A higher serum sodium concentration is related to an elevated blood pressure, and, in some patients, an inappropriate elevation of plasma aldosterone levels. Of the Japanese hypertensive patients, 10-14% exhibited serum sodium concentrations of 147 mmol/l or more and inappropriate elevations of aldosterone level (suppressed PRA and normal aldosterone level). The defect in these patients presumably lies in the inappropriately high secretion of aldosterone.