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.

Effect of cholera toxin on serum levels of thyrotropin and thyroid autoantibodies in biobreeding/Tokyo (BB/TKY) rats

The effect of cholera toxin (CT) on the thyroid-pituitary axis and the immune system was examined in Bio-Breeding/Tokyo (BB/TKY) rats, which spontaneously develop insulin-dependent diabetes mellitus (DM) and lymphocytic thyroiditis (LT). Intravenous administration of CT (5 micrograms/100 g body weight) every other week starting at 6 weeks of age resulted in a significant decrease in the serum thyrotropin (TSH) level at 12 and 14 weeks of age when compared with saline treated littermates. CT stimulated rat thyroid cells to proliferate in vitro. Furthermore, serum anti-thyroglobulin antibody (ATA) titers were also significantly decreased in 14-week-old rats treated with CT. In vitro ATA production by spleen cells from BB/TKY rats was inhibited by CT. Antibodies to thyroxine were detected in both CT-treated and control rats. It is of interest that the ratio of W3/25+ helper/inducer cells to OX8+ suppressor/cytotoxic cells was significantly decreased in CT-treated rats. However, there was no significant difference in the incidence of DM and LT between the two groups of rats. The present study showed that CT suppressed ATA production both in vivo and in vitro, and had a stimulatory effect on thyrocytes in BB/TKY rats.

Overexpression of low density lipoprotein receptor on Chinese hamster ovary cells generates foam cells

The atherosclerotic lesion is characterized by the presence of cholesterol-loaded foam cells. Chinese hamster ovary (CHO) cells do not normally store cholesteryl esters because low density lipoprotein (LDL) receptors are suppressed by exposure of these cells to LDL cholesterol. We transfected LDL receptor cDNA linked to the simian virus 40 early promoter into CHO cells (CHO 29) and found that LDL receptor binding in these cells was not suppressed by an excess amount of LDL cholesterol, indicating no regulation of the LDL receptor in CHO 29 cells. Furthermore, CHO 29 cells showed a high activity of LDL uptake and intracellular accumulation of cholesteryl esters. Light-microscopic examination demonstrated the resulting formation of foam cells in CHO 29 cells in the presence of 5 micrograms LDL/ml. These results demonstrated that foam cell changes in atherosclerotic lesions can be reproduced in CHO cells, whose LDL receptor activity is overexpressed, through the mechanism of LDL receptor-mediated endocytosis of native LDL.

Effect of alpha 1-blockade on diminished forearm blood flow in diabetics

An increased risk of atherosclerotic disease has been reported in patients with diabetes mellitus. The present study was therefore designed to determine forearm blood flow (FBF) in patients with essential hypertension or those with diabetes mellitus with or without hypertension. FBF determined by venous occlusion plethysmography decreased with age in controls as well as in patients with essential hypertension, whereas FBF in diabetics was significantly lower irrespective of age or blood pressure. As a result, vascular resistance was significantly higher in diabetics than in controls or patients with essential hypertension. Glycemic control in normotensive diabetics during 3 weeks significantly augmented a diminished FBF. alpha 1-Blockade by oral administration of 1 mg of prazosin also augmented the diminished FBF in diabetics, in association with a significant decrease in mean blood pressure and vascular resistance. These results suggest that FBF may be a simple and useful index for determining arterial and/or venous distensibility, and that alpha 1-blocker therapy, in addition to glycemic control, may be a first-line antihypertensive treatment for diabetics with associated hypertension.

Factors that influence the permeability assay of the outer membrane of Pseudomonas aeruginosa

Brief exposure of Pseudomonas aeruginosa to a temperature of 10 degrees C or lower caused a significant leakage of the periplasmic beta-lactamase into the medium. The extent of leakage increased as the incubation temperature was lowered to 4 degrees C and reached a maximum at 0 degrees C. Cells grown in the presence of beta-lactamase inducers were unsuitable for the permeability assay. It was found that the diffusion rates of beta-lactams through the outer membrane of P. aeruginosa were much lower than those previously reported, as assayed under refined conditions. The diffusion rates of beta-lactams in one of the mutants tested were an order of magnitude lower than those of the other strains, despite the fact that the outer membrane protein profile of the strain appeared to be indistinguishable from those of the others. These results suggest that beta-lactam antibiotics diffuse through the outer membrane of P. aeruginosa, at least partly, through a non-porin pathway.

High glucose concentration suppresses mesangial laminin B2 gene expression

To study the role of laminin in the rat mesangial cell attachment, cell adhesion to laminin-coated dishes was assayed by adding various amounts of a pentapeptide (YIGSR). YIGSR (20-100 micrograms/mL) inhibited the cell attachment to laminin-coated dishes. Mesangial laminin B2 messenger RNA (mRNA) levels were attenuated during exposure to 30 mM glucose or high osmolarity achieved by the addition of 25 mM choline chloride to 5 mM glucose (310 mOsm/kg H2O) for 3 hours. These results suggest that laminin, which may have a physiologic role in mesangial cell attachment, is produced in mesangial cells, and that the decrease of laminin B2 mRNA during hyperglycemia or exposure to high osmolarity may have some pathophysiologic significance in the development of diabetic nephropathy.

US and CT evaluation of cervical lymph node metastasis from oral cancer

A comparison was made of clinical diagnosis by ultrasound (US) and CT examination in 52 patients who had undergone radical neck dissection. The site, size, depth and other patterns concerning the nodes which could not be detected by physical examination was examined. US and CT examination proved superior to conventional clinical examination in detecting metastatic nodes. US and CT revealed that the disease stage in nine necks had increased from N1 to N2b and in seven of 11 necks from N0 to N positive. The characteristic features of US and CT diagnosis of metastatic lymph nodes were elucidated. Specifically, the diagnosis of cervical metastatic nodes by a combination of US and CT was found to be the most reliable method for detection of subclinical lymph nodes.

Serum or urinary concentration of type IV collagen in diabetics

Concentrations of serum or urinary type IV collagen, determined by sandwich enzyme immunoassay, were significantly elevated in diabetics compared to controls (P less than .01). Serum or urinary levels of type IV collagen were significantly increased in patients with microangiopathy compared to those without microvascular disease (P less than .05). Serum type IV collagen levels were also augmented in diabetics who showed an increased albumin index for 1 year. Serum levels of type IV collagen were not affected by any conditions of metabolic control. The measurement of serum or urinary type IV collagen may be a useful indicator for monitoring the development of diabetic microangiopathy, especially in early diabetic nephropathy.

Glucose-induced production of type IV collagen and laminin P1 from cultured human umbilical vein endothelial cells

To study the effect of high glucose on the production of type IV collagen and laminin P1 from the cultured human umbilical vein endothelial cells (HUVEC), we measured type N collagen and laminin P1 from HUVEC that were cultured under different conditions. The concentrations of type IV collagen in the cultured medium for high glucose (30 mM D-glucose) were significantly higher than those for low glucose (5.6 mM D-glucose), L-glucose (30 mM), or mannitol (30 mM). The increase of type IV collagen was dependent on the glucose concentration in the medium. The contents of type IV collagen in the cultured cells were also increased in high-glucose incubation compared with low glucose or L-glucose incubation. In contrast, the levels of laminin P1 in the medium cultured with high glucose were similar to those with low glucose or L-glucose. These results suggest that the increased production of type IV collagen may contribute to the thickening of basement membranes and may be linked to the development of diabetic nephropathy.

Effect of dietary calcium on renal prostaglandins

The present study was designed to clarify the possible role of renal prostaglandins (PGs) on blood pressure (BP) regulation during calcium (Ca) restriction or supplementation. Twelve normotensive women with a mean age of 21.2 years participated in the study. After 1 week of normal Ca intake (mean +/- SE, 536 +/- 2 mg/day), a low-Ca diet (163 +/- 1 mg/day) was given for a further 1 week. Additional asparagine Ca (3 g as Ca/day) was also given to half of the subjects. BP, heart rate, and serum total and ionized Ca concentrations were measured at the end of each period. Levels of Ca, sodium, PGE2, 6-keto-PGF1 alpha and thromboxane (TX) B2 excreted into urine were also determined. The plasma level of ionized Ca was significantly increased without any change in total Ca in both groups. Low and high Ca intake decreased and increased urinary Ca excretion by 28% and 56%, respectively. BP was not altered after Ca deprivation or loading. However, urinary PGE2 excretion was significantly augmented from 668.9 +/- 68.1 to 959.7 +/- 183.1 ng/day by Ca loading, whereas Ca deprivation decreased PGE2 excretion (695.4 +/- 108.1 to 513.2 +/- 55.2 ng/day). No changes were observed in 6-keto-PGF1 alpha or TXB2 urinary excretion. These results suggest that renal PGE2 synthesis is stimulated or decreased by 1-week Ca loading or deprivation, indicating a possible antihypertensive role of renal PGE2 during high-Ca intake in hypertensives.

Effects of slow-release nifedipine on nighttime blood pressure

With the advent of long-acting or slow-release antihypertensive drugs, we should be aware of a fall in nighttime blood pressure (BP) as well as daytime blood pressure. In the present study, casual BPs at the physician's office as well as ambulatory BP was recorded every hour throughout 24 hours with a noninvasive automated BP monitoring device in 24 essential hypertensives treated with slow-release nifedipine. Administration of slow-release nifedipine (20-40 mg, b.i.d.) decreased not only casual BPs but also ambulatory mean BP during the whole day or daytime (6 am to 10 pm). Slow-release nifedipine at 10 mg in the morning did not affect casual BPs at the office. However, mean BP obtained by ambulatory BP monitoring during the daytime was significantly attenuated. In addition, a profound fall in mean BP amounting to more than 20 mmHg during the night in some of the patients was observed during treatment with slow-release nifedipine not only at 20-40 mg (b.i.d.) but also at 10 mg once a day. These results suggest that we have to take into consideration the possibility that long-acting hypotensive agents may cause a great fall in nighttime BP during sleep, especially in the elderly.

[Studies on thyroid hormone autoantibody (THAA) in 2 cases of Graves' disease with spuriously high free thyroxine values]

Two patients with Graves' disease treated with methimazole (MMI) showed a discrepancy between serum free T4 (FT4) values and other hormone values (especially total T4) which was due to the presence of potent binding activity to labelled T4 analogue (125I-aT4) in their serum. This activity was demonstrated to be in immunoglobulin G (IgG) with kappa light chain isotype in both patients. The binding of 125I-aT4 to their serum was inhibited by unlabelled T4 in a dose-dependent manner. Autoantibodies had almost identical binding affinity to T4 and aT4, although they precipitated more radioactivity when 125I-aT4 was used. The binding of IgG purified from patients' sera to labelled T4 or aT4 was not greater than the corresponding sera, suggesting that the thyroxine binding proteins did not interfere with the assay. Since the specific radioactivity of 125I-aT4 is almost 10 times higher than that of 125I-T4, autoantibodies can precipitate almost 10 times more radioactivity in the FT4 assay than the total T4 assay, thus leading to the spuriously high FT4 values and large discrepancy between FT4 and TT4 values.

Clinical significance of ambulatory blood pressure monitoring. Evaluation of severity of hypertension, efficacy of treatment and effects on nighttime blood pressure

Blood pressure (BP) obtained by the physician in his office and ambulatory BP recorded every hour throughout 24 hours with a noninvasive automated BP monitoring device were compared in 10 normotensives and 162 hypertensives. Casual BPs significantly correlated with averages in ambulatory BPs (ABPs) throughout the whole day, day (7 am - 10 pm) and night (0-5 am). However, it was noted that 6 of 10 normotensives and all of the moderate to severe hypertensives had ABPs of more than 150/90 mmHg at least once during the 24-hour period. The incidence of ABPs greater than 150/90 mmHg among all readings was higher in untreated and treated hypertensives with diastolic BPs in the office of more than 105 mmHg, and, when checked along with the clock time, higher not only in the morning but also in the evening. On the other hand, one-third or one-fifth of treated hypertensives with diastolic office BPs less than 90 mmHg or between 90 and 105 mmHg respectively had ABPs less than 150/90 mmHg throughout the whole day. When the effect of nicardipine (60 mg, t.i.d.) or slow-release nifedipine (27.3 +/- 3.0 mg, b.i.d.) on minimum BP during the night was analyzed, long-acting nifedipine decreased BP throughout the night to levels not significantly different from normotensive controls, whereas short-acting nicardipine did not affect nighttime BPs. These results suggest that simple ABP monitoring throughout the day gives us useful information to evaluate the severity of hypertension and the efficacy of antihypertensive medication as well as to avoid overtreatment with long-acting hypotensive agents resulting in a great fall in BP during sleep.

Effect of captopril on glucose concentration. Possible role of augmented postprandial forearm blood flow

The goal of this study was to evaluate the effects of captopril on plasma glucose concentration. The daily profiles of the plasma glucose levels were determined in 12 non-insulin-dependent diabetic normotensive subjects, treated with or without captopril at a dose of 25 mg 3 times/day. Forearm blood flow was also measured by strain-gauge plethysmography. Administration of captopril improved the daily profile of the plasma glucose level. Postprandial forearm blood flow was also augmented 2 h after a meal. These results suggest that angiotensin-converting enzyme inhibitors may improve glucose metabolism in diabetic subjects, possibly through enhancement of blood flow to skeletal muscle.

[Ultrasound and CT evaluation of cervical lymph node metastasis of oral cancer]

A comparison of the results of clinical diagnosis and ultrasound (US) and CT examinations was carried out in 43 patients who underwent radical neck dissection. We examined the site, size, depth and other features of lymph nodes which were unable to be detected by physical examination. US and CT proved superior to conventional clinical examination in detecting metastatic nodes. US and CT revealed that the disease in seven necks (12%) was not N1 but N2b, while in six of nine necks it changed from N0 to N positive. The features of metastatic lymph nodes on US and CT were clarified, and it was found that the detection of cervical metastatic nodes by a combination of US and CT is the most reliable method for assessing metastasis from tumors of the oral cavity.

The mechanism for the discrepancy between serum total and free thyroxine values induced by autoantibodies: report on two patients with Graves' disease

The sera from two patients with Graves' disease gave abnormally high serum free T4 values as compared with the total T4 and other hormone values, suggesting the presence of autoantibodies to labelled T4 analogue used in the Amersham free T4 assay kit. The autoantibodies appeared to develop after the initiation of methimazole therapy and disappeared again after the cessation of methimazole. This binding activity to labelled T4 analogue was demonstrated to be in the immunoglobulin G with a kappa light chain isotype in both sera, and was displaced by unlabelled T4 in a dose-dependent manner. The binding of immunoglobulin G purified from these sera to labelled T4 or T4 analogue was found to be almost identical to that of the corresponding serum binding. Since the specific radioactivity of labelled T4 analogue used in the Amersham free T4 assay kit is about 10 times higher than that of the labelled T4 in the Amersham total T4 assay kit, serum free T4 determinations are much more vulnerable to thyroid hormone autoantibodies. Thus, in the presence of autoantibodies, a large discrepancy develops between free T4 and total T4 values.

Hyperreninemia due to increased renal renin synthesis in BioBreeding Worcester rats

It is well known that diabetes mellitus is often associated with hypertension. We previously reported the unresponsiveness of renin release to volume depletion with impaired renal prostaglandin E2 synthesis in rats with streptozotocin-induced diabetes. However, we have found that BioBreeding Worcester rats, spontaneously susceptible to diabetes mellitus either before or after the onset of diabetes, showed a pronounced fourfold to ninefold increase in plasma renin activity in comparison with control Wistar rats. Furthermore, these rats developed mild hypertension as high as 134 mm Hg after the age of 90 days. The hyperreninemia responded to 1-week sodium loading or restriction; the blood pressure increased during sodium loading. Oral administration of captopril (30 mg/kg) for 1 week resulted in a large blood pressure decrease (-47.1 +/- 5.9 mm Hg, n = 10) in comparison with controls (-17.0 +/- 4.7 mm Hg, n = 12). Vascular response to angiotensin II was also attenuated. Plasma angiotensin II levels were 5.7-fold higher and associated with a 1.5-fold increase of plasma aldosterone concentration compared with control rats, whereas angiotensinogen-plasma concentrations were lower than in control rats. The renal renin content determined enzymatically or histochemically was more enhanced in BioBreeding Worcester rats than in control rats, but the renal renin messenger RNA levels did not differ. These results suggest that the strain-specific hyperreninemia in BioBreeding Worcester rats might be due to posttranscriptional abnormalities of renal renin synthesis. Further work is needed to elucidate the specific mechanism or mechanisms responsible.

MHC class II molecules (Ia-antigens) on macrophages in BB/W rats

The percentage, absolute number and expression of Ia-antigen of macrophages (Mø) in peripheral blood cells (PBC) and splenocytes from Bio-Breeding/Worcester (BB/W) rats were evaluated. The percentage of Mø in PBC and splenocytes from BB/W rats was significantly higher than those in normal Wistar rats from Clea Japan Inc. (NW/C) and Charles River Japan Inc. (NW/CR). The percentage of Ia-positive Mø in PBC and splenocytes from BB/W rats was significantly increased compared with that in NW/C rats. On the other hand, there was no significant difference in the percentage of Ia-positive Mø of PBC between BB/W and NW/CR rats, and the percentage of Ia-positive Mø in the spleen from BB/W rats was significantly lower than those in NW/CR rats. Thus, the quantity of MHC class II molecules on circulating Mø is not related to the pathogenesis of diabetes mellitus in BB/W rats.

Increased renal TXA2 synthesis in diabetes mellitus: simultaneous determination of urinary TXB2 and 2,3-dinor-TXB2

The present study was designed to determine urinary excretion of kallikrein(KAL)-kinin as well as prostaglandin (PG) E2, TXB2 and 2,3-dinor-TXB2, a major urinary metabolite of TXA2 synthesized in platelets, by specific RIAs in patients with diabetes mellitus (DM). KAL or kinin excretion in 26 type II DM did not differ from control values obtained in 18 age-matched healthy subjects (C), although DM with HbA1 greater than 11% excreted less KAL. Urinary PGE2 excretion (7.6 +/- 2.8 ng/mg creatinine, mean +/- SE) was significantly lower in DM compared to C (17.5 +/- 3.9, p less than 0.05), while DM excreted more TXB2 (0.57 +/- 0.09, p less than 0.01) and 2,3-dinor-TXB2 (0.56 +/- 0.12, N.S.) than C (0.19 +/- 0.02 or 0.33 +/- 0.01). DM with or without mild proteinuria demonstrated lower PGE2, but higher TXB2 and 2,3-dinor-TXB2 excretion. A positive correlation of TXB2/2,3-dinor-TXB2 with proteinuria was observed in this group. However, in DM with massive proteinuria over 500 micrograms/mg creatinine, TXB2 and 2,3-dinor-TXB2 excretion decreased to levels almost identical to C. As a whole, a ratio of TXB2 to PGE2 or 2,3-dinor-TXB2 in DM was significantly higher than in C. The results suggest that a relative preponderance of TXB2 to 2,3-dinor-TXB2 may indicate an augmented renal, in addition to platelet, TXA2 synthesis. An excessive vasoconstrictive and proaggregatory TXA2 renal synthesis, concomitant with a decrease in vasodilatory and antiaggregatory PGE2, may have profound effects on renal functions such as protein excretion in DM.