Plasma amino acid profile is associated with visceral fat accumulation in obese Japanese subjects

What is already known about this subject •  Asians with metabolic complications associated with obesity, a low body mass index and a low waist circumference have a greater proportion of visceral adipose tissue for a given amount of total body fat compared with Europeans. •  Apparent obese humans and obese animal models show an elevation of branched-chain amino acid levels in plasma. •  A multivariate logistic regression model of plasma free amino acids has been used to screen for several types of cancers in clinical settings. What this study adds •  A specific formula incorporating six amino acid values (Ala, Gly, Glu, Trp, Tyr and branched-chain amino acid) was developed for discrimination of subjects with high visceral fat area by multivariate logistic regression analyses. •  The generated amino acid formula was strongly correlated with visceral fat area in both apparent and non-apparent obese subjects. •  Measuring plasma free amino acids can be used to distinguish the non-apparent visceral obesity in clinical settings in Asian populations.

SUMMARY

Metabolic complications associated with obesity are becoming more common among Japanese subjects. However, visceral fat accumulation is not always apparent by measuring body mass index (BMI) or waist circumference in Asian populations because of the physiological characteristics particular to those ethnicities. Excess visceral fat accumulation raises the odds ratio for developing cardiovascular disease. Thus, high-throughput determination of the amount of abdominal adipose tissue is necessary. We hypothesized that accumulating visceral fat alters the peripheral amino acid profile and that a multivariate logistic regression model of plasma free amino acids can distinguish visceral obesity. A total of 1449 Japanese subjects (985 males and 464 females) who had undergone a comprehensive health screening were enrolled in this study. The visceral fat area was determined using computed tomography imaging, and a plasma free amino acid index to identify high visceral fat areas (≥100 cm(2) ) was developed. The sensitivity and specificity values of the generated amino acid index were 80% and 65%, respectively. In particular, the sensitivity of the generated index to identify subjects with non-apparent visceral obesity (BMI < 25 kg m(-2) ; visceral fat area ≥ 100 cm(2) ) was much greater than that of the waist circumference (73% vs. 46%, respectively). This index's high sensitivity and specificity may be the result of specific alterations in the patients' amino acid profiles, which were specifically correlated with the visceral fat areas and not with subcutaneous fat areas. This profile can be used as a predictor of elevated visceral obesity and a risk assessment tool for metabolic complications in Asian populations.

Pharmacodynamics of menatetrenone and effects on bone metabolism in continuous ambulatory peritoneal dialysis patients

Prevention of osteoporosis and renal osteodystrophy are important for the long-term quality of life in dialysis patients. We examined whether administration of menatetrenone (vitamin K2) improves bone metabolism in continuous ambulatory peritoneal dialysis (CAPD) patients. Administration of a single dose of menatetrenone (15 mg) revealed that the 24-h pharmacodynamics in CAPD patients were comparable to those in control individuals. In a 12-month period of oral menatetrenone administration (45 mg/day), eight stable CAPD patients were studied for blood-bone metabolism parameters and for bone mineral content. Blood concentration of menatetrenone was detectable during the experiment period. Only at 12 months did active vitamin D3 and bone-type alkaline phosphatase (ALP) fall significantly, while total ALP rose significantly. Bone mineral density measured by dual-energy X-ray absorptiometry remained at the same level throughout the study period, suggesting that menatetrenone may protect against bone mineral loss in CAPD patients. These results show that the same dose of oral menatetrenone can be given to CAPD patients as to control individuals, and that menatetrenone can be used safely for 1 year in CAPD patients.

Urinary prostaglandin D synthase (beta-trace) excretion increases in the early stage of diabetes mellitus

OBJECTIVE

Circulating levels of lipocalin-type prostaglandin D synthase (L-PGDS)/beta-trace reportedly increase in renal failure as well as in cardiovascular injuries. We investigated the alterations of L-PGDS in urine and plasma in the early stage of type-2 diabetic patients.

METHOD

Thirty-six type-2 diabetic patients and 29 normal subjects were studied. Overnight spot urine and plasma samples were obtained in the morning. L-PGDS was measured by ELISA method using anti-L-PGDS antibody. Variables indicating renal function were determined.

RESULTS

Plasma L-PGDS concentration was slightly higher in the patients with diabetes mellitus than in the control subjects, whereas the urinary L-PGDS excretion almost doubled in the diabetic patients as compared with that in the control subjects. Plasma L-PGDS was determined by plasma creatinine (Cr) concentration while urinary L-PGDS excretion was correlated solely with urinary protein excretion. There was no relationship between plasma L-PGDS concentration and urinary L-PGDS excretion. The averaged plasma concentration of L-PGDS in the diabetics with a normal Cr level in plasma, corresponding to that in the controls, was determined by the plasma Cr concentration. On the other hand, the urinary L-PGDS excretion was determined by the amount of proteinuria and greater in the diabetics with a normal Cr level in plasma than in the controls even when the patients exhibited urinary protein excretion equal to that in the control subjects.

CONCLUSIONS

Urinary L-PGDS excretion increased in the early stage of kidney injury in patients with type-2 diabetes mellitus. The urinary excretion was correlated independently with urinary protein excretion even when there was no difference in urinary protein or albumin excretions, thereby suggesting that urinary L-PGDS excretion is possibly a more sensitive indicator of renal injuries than proteinuria. Urinary L-PGDS may thus predict the progression of renal injuries in diabetic patients.

Mechanism of oral absorbent AST-120 in lipid abnormalities in experimental uremic rats

BACKGROUND

We have reported that oral sorbent AST-120 (AST) is effective in delaying the induction of dialysis in patients with chronic renal failure (CRF) because of its effect on lipid metabolism. To clarify the precise mechanism of AST in lipid abnormalities in CRF, we examined the effect of AST on plasma lipid profile, total bile acids (TBA), and lipoprotein lipase (LPL) activity in experimental uremic rats.

METHODS

Uremic rats were prepared using male Wistar rats by ligating 5/6 of the renal artery. Uremic rats were randomly divided into two groups as follows: a control group in which rats were maintained on the standard diet and an AST group in which rats were maintained on a diet containing 5 g of AST per 100 g of standard diet for 10 weeks. Plasma LPL activity was measured as free fatty acid (FFA) generation after intravenous administration of heparin.

RESULTS

Plasma creatinine at 1.5 +/- 0.1 mg/dl was lower in the AST group than the 1.9 +/- 0.5 mg/ml level in the control group. AST significantly decreased plasma total cholesterol from 192 +/- 29 to 142 +/- 25 mg/dl, triglycerides from 198 +/- 71 to 99 +/- 38 mg/dl, and TBA from 19.6 +/- 2.6 mumol/liter to 8.8 +/- 3.5 mumol/ml. Plasma LPL activity at 0.22 +/- 0.01 mumol FFA/min/hr was significantly higher in the AST group than 0.15 +/- 0.03 mumol FFA/min/hr in the control group.

CONCLUSIONS

These results suggest that AST may improve plasma lipid abnormalities by binding to bile acids in the intestinal lumen and preventing their reabsorption and inhibiting the reduction of LPL activity in experimental uremic rats.

Reassemblage of primary cell aggregates and modulation of subcortical connections in the thalamic relay nucleus: effects of vibrissal damage in the developing whisker-to-barrel pathway in the mouse

To investigate the mechanisms underlying the reorganization of barrels in the whisker-tobarrel pathway, the facial vibrissae of mice were damaged by electrocauterization at alternate positions on either postnatal day 0 (P0) or P3, before or after the onset of cell aggregation in the thalamus and cortex. Animals were subsequently killed on P8, topographical changes were examined by cytochrome C oxidase histochemistry, and afferent connections were identified using DiI tracer. The cytoarchitecture was characterized with bisbenzimide counterstain. Regardless of when damage was done, the reorganized barreloids and barrels in the thalamus and cortex, respectively, were integrated in an array that represented the topography of undamaged vibrissae. In the brainstem, although the original framework of the array was preserved, defective cell aggregates remained, possibly still in contact with damaged vibrissae. During normal development, on P0 cell aggregates are formed only in the brainstem, and begin to be organized at the other levels of the pathway on P3. Therefore, when damage is induced on P3, the primary cell aggregates are replaced by new, possibly recombined, cell aggregates in the thalamus and cortex to represent the new peripheral topography. The presumably recombined aggregates indicate that cell reassemblage occurred between neighboring cell aggregates. Concomitant with these changes, afferent fibers originating in the brainstem and thalamus extended their terminal arborizations to delineate the new cell aggregates in the thalamus and cortex, respectively. These findings indicate that activity-dependent competitive interactions of afferents may play a crucial role in organizing the topography of cell aggregation and reassemblage in response to vibrissal damage at each level of the pathway.

Differential fasciculation of follicular nerves for transferring specifically localized cues of the vibrissa rudiments to the central trigeminal sensory system in mice, as exploited with DiI and DiA labeling

Vibrissa connections play a decisive role in setting the somatotopic coordinates in the trigeminal sensory system. Although previous studies have examined the development of peripheral patterning, certain questions are still in dispute, for example, the way vibrissa connections are structured, and the relationship between periphery and central organization, and ganglion cell organization. In order to fill the blanks left by previous studies, the extension of ganglionic branches and the formation of vibrissa connections were reexamined by using fluorescent carbocyanin dyes, DiI and DiA, during embryonic days 10 to 14 in mouse. Whole-mount preparations satisfactorily demonstrated the ganglionic fiber system, which allowed detailed analysis at both macroscopic and microscopic levels. We show here that the differential fasciculation of follicular nerves is the critical process for organizing vibrissa connections which modulate the initially extending fiber pattern. Follicular nerves developed by fine fibers arising from initially ordered root fascicles, so as to connect with vibrissa rudiments that developed on the facial prominences. During differential fasciculation, ganglion cells were segregated into distinct groups by the vibrissa connections, whereas central fiber terminals did not yet develop specific structures in the nuclear region. In the primary order of the trigeminal sensory system, vibrissa connections in the periphery were organized before those of the central structure. These results indicate that trigeminal ganglion cells have a critical binomial function in order to transfer the somatotopic relations among vibrissa rudiments into the topographic coordinates of the central system.

Influence of smoking on serum carcinoembryonic antigen levels in subjects who underwent multiphasic health testing and services

We quantified the effect of smoking on serum carcinoembryonic antigen (CEA) levels in 1341 subjects who underwent the multiphasic health testing and services in our center. Four hundred and sixty seven of them were smokers and the rest were nonsmokers. In males subjects, serum CEA levels were significantly higher in smokers (3.11 +/- 1.8 ng/ml) than in nonsmokers (2.14 +/- 1.8 ng/ml) (mean +/- SD; p < 0.01). For females, however, the levels had no significant differences between smokers (2.11 +/- 0.91 ng/ml) and nonsmokers (1.87 +2- 1.3 ng/ml). The CEA-positive subjects were 44, of whom 32 were male custom heavy smokers, and only 2 of them had gastrointestinal cancer. We concluded that the serum CEA level was influenced by smoking especially in males and its clinical significance for detection of carcinoma was doubtful.

Ultrasonographically assessed carotid intima-media thickness and risk for asymptomatic cerebral infarction

Cerebral infarction (CI) is still a leading cause of death in Japan. Thus, the management of risk factors for CI as primary prevention is one of the most important tasks in multiphasic health testing and services. To determine whether carotid intima-media thickness (IMT) is a risk for CI, ultrasonographically assessed carotid IMT was compared between normal subjects (N) and subjects with asymptomatic CI (ACI) in 243 subjects who underwent human brain dry dock. ACI was found in 68 people (28.0%). Age, body mass index, and mean blood pressure were higher in ACI than in N. Also, atherogenic index was higher in ACI than in N. Carotid IMT was significantly thicker in ACI than in N. Furthermore, incidence of atherogenic plaque in ACI was significantly higher than that in N. In conclusion, not only aging, obesity, blood pressure, and plasma lipids, but also carotid IMT may be a risk for ACI.

Selection of marker-free transgenic plants using the isopentenyl transferase gene

We have developed a new plant vector system for repeated transformation (called MAT for multi-auto-transformation) in which a chimeric ipt gene, inserted into the transposable element Ac, is used as a selectable marker for transformation. Selectable marker genes conferring antibiotic or herbicide resistance, used to introduce economically valuable genes into crop plants, have three major problems: (i) the selective agents have negative effects on proliferation and differentiation of plant cells; (ii) there is uncertainty regarding the environmental impact of many selectable marker genes; (iii) it is difficult to perform recurrent transformations using the same selectable marker to pyramid desirable genes. The MAT vector system containing the ipt gene and the Ac element is designed to overcome these difficulties. When tobacco leaf segments were transformed and selected, subsequent excision of the modified Ac produced marker-free transgenic tobacco plants without sexual crosses or seed production. In addition, the chimeric ipt gene could be visually used as a selectable marker for transformation of hybrid aspen (Populus sieboldii x Populus grandidentata). The chimeric ipt gene, therefore, is an attractive alternative to the most widely used selectable marker genes. The MAT vector system provides a promising way to shorten breeding time for genetically engineered crops. This method could be particularly valuable for fruit and forest trees, for which long generation times are a more significant barrier to breeding and genetic analysis.

The effect of age on glucose tolerance and plasma insulin level in hypertensive and normotensive subjects

To elucidate the effect of aging and blood pressure on glucose tolerance, we examined the subjects who received 75g OGTT annually for 10 years. They were classified into 2 groups by blood pressure, and into 4 groups by age. The study group consisted of 34 cases (mean 62 years old), including 11 hypertensive (HT) and 23 normotensive (NT) control. All cases had their body weight fluctuate in less than 4 kgs. After blood pressure was measured, blood was drawn for determination of plasma glucose and insulin concentrations in each subject before 75g OGTT and 30, 60, 90, 120 minutes afterward. sigma BS and sigma IRI were defined as the sum of 5 points in BS and IRI, respectively. Insulinogenic index (I.I) was defined as deltaIRI/deltaBS in 30 min. sigma IRI/sigma BS and I.I of each year were calculated serially. They were compared between HT and NT group, and among 4 groups of age; 40s, 50s, 60s and 70s. sigma IRI/sigma BS was significantly decreased in both HT and NT groups (0.52 +/- 0.05 (mean +/- SE) to 0.29 +/- 0.04; p <0.0001 vs. 0.42 +/- 0.05 to 0.23 +/- 0.02; p < 0.0001, respectively). But significant difference between the 2 groups was not observed. No significant difference of sigma IRI/sigma BS among 4 groups of age was found. There were significant differences between I.I of the first year and that of several years, but they did not correlate linearly. These data indicate that the effect of age on the diminution of sigma IRI/sigma BS was significant for 10 years follow-up of the same subjects in both HT and NT groups. But there were no significant differences in classified groups by blood pressure and age.

Remodelling in the array of cell aggregates in somatotopic representation of the facial vibrissae through the trigeminal sensory system of the mouse

The disposition of the facial vibrissae of the mouse is represented as a matrix-like array of cell aggregates in rows and columns at every station of the whisker-to-barrel pathway. In order to evaluate the role of each station in this pathway, lesions were made in the facial vibrissae of the mystacial group on P0-P3, and the animals were sacrificed on P8. The effects of the lesions on the cell aggregates in the array were analyzed by using cytochrome oxidase and gallocyanin cell-staining methods. Division of cell aggregates in the array was controlled by row basis interactions through the pathway up to the cerebral cortex. In this organization, affected cell aggregates which corresponded to the damaged vibrissae were eliminated and/or fused together in the array of the thalamic relay nucleus. On the basis of thalamic modification, the final array of cell aggregates was remodelled in the cerebral cortex. In contrast, affected cell aggregates remained degenerative spaces at the original sites in the array in relation to the damaged vibrissae in the brain stem trigeminal nuclear complex. These results indicate that a protoframework with row basis orientation for the division of cell aggregates is prepared in every station of the pathway at the time of lesioning, and adjustment of subcortical alterations in the thalamic relay nucleus is a decisive process to let the cerebral cortex remodel the topographic array of cell aggregates.

[A case of sporadic acute type A hepatitis associated with acute renal failure]

We report a case of sporadic acute type A hepatitis associated with acute renal failure, due to mesangioproliferative glomerulonephritis and interstitial nephritis. A 42 year-old-man was admitted to Mitsui Memorial Hospital because of jaundice and oliguria with fever in February, 1989. His serum creatinine was 12.2 mg/dl, BUN 87 mg/dl, GOT 57 U/l and GPT 358 U/l. The serum IgM antibody to hepatitis A virus was positive, which indicated recent infection with hepatitis A virus. Hemodialysis and steroidal therapy were started, and the patient's acute renal failure and liver dysfunction ameliorated within one month. Light microscopic examinations showed an increased number of mesangial cells and an increased amount of mesangial matrix, and also showed inflammatory cell invasion in the interstitium. Electron microscopic examinations showed proliferation of mesangial cells and matrix, and a dense deposit along the basement membrane. On immunofluoresent studies, fine granular deposits of IgA and Clq were observed in the mesangium.

[A case of Crow-Fukase syndrome associated with membranoproliferative glomerulonephritis]

Crow-Fukase syndrome is a rare multiorgan disorder. Although renal disorders, such as proteinuria, and renal impairment, have been observed in half the cases of this syndrome, there have been few reports describing the renal lesions. We report here a case of this syndrome associated with membranoproliferative glomerulonephritis. A 43-year-old woman was referred to our hospital because of hyperglycemia. She had also been suffering from hyperpigmentation, hepatosplenomegaly, lymphadenopathy, polyneuropathy and endocrine dysfunction, including diabetes mellitus and amenorrhea. Serum electrophoresis showed M protein and immunoelectrophoresis revealed IgA (lambda). Bone marrow aspiration showed a slight increase in the number of plasma cells. Urine protein was 30 mg/dl, BUN was 17 mg/dl and creatinine 0.8 mg/dl. Light microscopic examinations showed enlargement of glomeruli with proliferation of mesangial cells and matrix, a lobular pattern of the glomeruli and thickening of the glomerular basement membrane and associated double contour. Electron microscopic examinations showed thickened capillary walls, associated mesangial interposition and subendothelial dense deposits. Moreover, fine granular deposits of IgM, C3, and fibrinogen along the basement membrane were observed on immunofluorescent studies.

Changes of the expression and distribution of retinoic acid receptors during neurogenesis in mouse embryos

The expression and distribution of three retinoic acid receptors, alpha, beta, and gamma, were investigated in the CNS of mouse embryos during development. mRNAs and protein of RAR-beta that were expressed in the spinal cord of the 12.5-day mouse embryo decreased during development but they were not decreased in the brain. The RAR-beta-positive cells were already present in the ventral region of the spinal cord of 10.5-day mouse embryos, gradually appeared in the dorsal region during development and then disappeared from the spinal cord after birth. In the brain, RAR-beta-positive cells were detected in the mesencephalon and rhombencephalon but not in the telencephalon of the 12.5-day mouse embryos. RAR-beta-positive cells were present in the hippocampus and cingulum but not in the neocortex of 14.5-day mouse embryos. Most neurons in the hippocampus of 16.5-day mouse embryos and the cortex of newborn mice were RAR-beta-positive. In the spinal cord, RAR-alpha mRNAs and proteins also decreased during development but more gradually than RAR-beta mRNAs and proteins. During development, the distributions of RAR-alpha and -beta in the spinal cord and brain did not differ substantially. The main difference was the appearance of a subtypes of RAR-alpha, a 52-kDa protein, in the brain of newborn mice. On the other hand, RAR-gamma proteins were only faintly detected in the spinal cord and the brain of the mice during the embryonal stages but these increased after birth. The distribution of RAR-alpha- or -beta-positive cells were consistent with the neurogenesis during development in the spinal cord and brain.

Corticotropin-releasing hormone, proopiomelanocortin, and glucocorticoid receptor gene expression in adrenocorticotropin-producing tumors in vitro

To differentiate between ectopic ACTH syndrome and Cushing's disease, gene expression of corticotropin-releasing hormone (CRH), proopiomelanocortin (POMC), and glucocorticoid receptor was examined in 10 pituitary adenomas (Cushing's disease) and in 10 ectopic ACTH-producing tumors. CRH increased plasma ACTH levels in all patients with Cushing's disease and in five patients with ectopic ACTH syndrome whose tumors contained CRH and CRH mRNA. In five CRH nonresponders, CRH was not detected in tumors that contained no CRH mRNA or that contained only long-size CRH mRNA. Dexamethasone (Dex) decreased plasma ACTH levels in all patients with Cushing's disease and in three patients with ectopic ACTH-producing bronchial carcinoid. These tumors contained glucocorticoid receptor mRNA. CRH increased and Dex decreased ACTH release and POMC mRNA levels in pituitary adenoma and bronchial carcinoid cells. PMA increased POMC mRNA levels only in carcinoid cells. These results reveal characteristics of ectopic ACTH-producing tumors: long-size CRH mRNA and PMA-induced POMC gene expression. In addition, there are two ectopic ACTH syndrome subtypes: tumors containing ACTH with CRH (CRH responder) and tumors without CRH. Dex decreases ACTH release and POMC mRNA levels in some bronchial carcinoids. Therefore, CRH and Dex tests have limited usefulness in differentiating between Cushing's disease and ectopic ACTH syndrome.

A patient with a prolactinoma associated with an aldosterone producing adrenal adenoma: differences in dopaminergic regulation of PRL and aldosterone secretion

A patient with a rare combination of prolactinoma and aldosterone producing adrenal adenoma (APA) was reported in relation to studies concerning dopaminergic regulation of PRL and aldosterone secretion. The patient is a 38-year-old female with plasma PRL and aldosterone concentrations (PAC) of 563 ng/ml and 54 ng/dl, respectively. A bolus of 10 mg of metoclopramide significantly increased plasma PRL in 6 normal subjects and in 4 patients with APA, whereas the responses were blunted in 7 patients with prolactinoma and in our patient. The response of aldosterone to metoclopramide was less than that of PRL, but similar in all studied subjects, indicating that the dopaminergic inhibition of aldosterone secretion is less than that of PRL in normal subjects and did not change in patients with APA or prolactinoma. Oral administration of 2.5 mg of bromocriptine suppressed plasma PRL significantly in all the subjects studied, but did not produce any consistent changes in PAC. Discrepancies in the response of PRL and aldosterone to metoclopramide and to bromocriptine suggest a difference in the dopaminergic regulation of PRL and aldosterone secretion in both normal subjects and patients with prolactinoma and APA. It is unlikely that reduced dopaminergic inhibition is the basis for hypersecretion of PRL and aldosterone in our patient.

Mechanisms of hypertension induced by erythropoietin in patients on hemodialysis

To investigate the mechanisms of hypertension induced by recombinant human erythropoietin (rHuEPO) in patients on hemodialysis (HD), mean blood pressure (MBP), plasma renin activity (PRA), whole blood viscosity, blood volume (BV), cardiac index (CI) and total peripheral resistance index (TPRI) were measured before and after treatment with rHuEPO for 3 months in 9 patients on HD. Pressor responsiveness to exogenous norepinephrine (NE) and angiotensin II (AII) were also compared before and after treatment. Four patients were 'responders' (R) whose MBP increased by more than 10 mmHg, and 5 patients were 'non-responders' (non-R) whose MBP was unchanged or increased by less than 10 mmHg. Initial PRA and TPRI were significantly higher and BV was significantly lower in R than in non-R. After treatment, TPRI was increased in both groups, but CI was decreased in non-R. There was a significant correlation between changes in MBP and blood viscosity to rHuEPO. Pressor responsiveness to NE and AII were significantly enhanced after rHuEPO treatment in responders. These results suggest that inappropriate cardiovascular responses to the correction of anemia, increased blood viscosity, and enhanced pressor responsiveness may participate in the development of rHuEPO-related hypertension.

Pathophysiological role of endothelin in renal transplantation

To assess the pathophysiological role of endothelin (ET) in the early post-transplantation period, we followed plasma ET concentrations for 2 months from 1 week prior to surgery in four renal transplant patients. Plasma ET concentrations were elevated before transplantation in all patients. In two patients who developed marked pretibial edema, plasma ET concentrations increased before the onset of edema and before the increase in plasma atrial natriuretic peptide (ANP) concentrations, and remained high while the edema persisted. In the other two patients without edema, plasma ET and ANP concentrations fell toward normal immediately after transplantation. Plasma ET concentration increased transiently again in one of these patients when acute rejection occurred. After recovery from this rejection episode, the plasma ET concentration again fell to the normal range. There were significant correlations between plasma ET concentrations and changes in body weight and urine volume. These results suggest that the plasma ET concentration may reflect the function of transplanted kidneys and that ET may modulate body fluid volume regulation after transplantation. In addition, ET may participate in the pathogenesis of acute rejection.

Echocardiographic findings in hemodialysis patients treated with recombinant human erythropoietin: proposal for a hematocrit most beneficial to hemodynamics

We investigated the hemodynamic effects of the correction of anemia with recombinant human erythropoietin (rHuEPO) in 28 hemodialysis patients with severe anemia. Echocardiograms were recorded before the administration of rHuEPO (period I) with a hematocrit of 19.2 +/- 1.5% (mean +/- SD) and repeated twice (periods II and III) when the hematocrit was increased to 25.7 +/- 1.1% and to 30.0 +/- 1.0%. Left ventricular end-diastolic dimension (LVDd) decreased from 51.0 +/- 6.1 to 48.8 +/- 5.8 and to 48.3 +/- 7.1 mm, but no changes were observed in left ventricular end-systolic dimension. Cardiac output (CO) decreased from 5.89 +/- 1.46 to 5.00 +/- 1.44 and to 4.67 +/- 1.33 l/min. The thickness of the interventricular septum and the left ventricular posterior wall remained unchanged. Blood pressure was kept rather constant, although antihypertensive therapy needed to be adjusted to prevent the occurrence or aggravation of hypertension. Total peripheral resistance increased from 1481 +/- 359 to 1832 +/- 487 and to 1946 +/- 493 dynes.sec/cm5. The decreases in LVDd and CO were significant between periods I and II, without further changes between periods II and III. More antihypertensive therapy was needed in period III than in period II. Similar echocardiographic results were observed in 10 patients in whom antihypertensive therapy was not required throughout the study. In conclusion, an increase in hematocrit to 25% would be appropriate in order to obtain an effective hemodynamic improvement with rHuEPO therapy in dialysis patients although a higher hematocrit level might be desirable in order to improve working capacity.

Expression of cellular retinoic acid binding protein in the developing nervous system of mouse embryo

The expression of cellular retinoic acid binding protein, CRABP, in developing mouse embryos was immunohistochemically analyzed. Differentiating young neurons and neuronal fibers in the myelencephalon, metencephalon, mesencephalon and spinal cord in 10.5- and 12.5-day embryos showed intense expression of CRABP, but undifferentiated cells in the neural tube did not. Neural tissue in 16.5-day embryos expressed less amount of binding protein than the tissues of the younger stages. These expressions of CRABP suggest that retinoic acid participates in neurogenesis at early developmental stages via expression of cellular retinoic acid binding protein.

Regulatory mechanisms of erythropoietin levels in dialysis patients

We described a radioimmunoassay system for measuring blood erythropoietin (Epo) levels using recombinant human Epo and evaluated the regulatory mechanisms of Epo in dialysis patients. A satisfactory dose-response relationship for Epo levels was observed within the wide range of 3-250 mU/ml with a sensitivity of approximately 5 mU/ml. The Epo levels were found to be 16.1 +/- 8.6 mU/ml (m +/- SD) in 422 uremic patients on maintenance dialysis and 17.1 +/- 7.2 mU/ml in 86 normal subjects. The Epo levels were not statistically different between the two groups, although the hematocrit was significantly lower in the dialysis patients. No correlation was observed between the Epo levels and hematocrit in the dialysis patients. Patients with polycystic kidneys had higher hematocrits and Epo levels than patients with chronic nephritis. No changes in Epo levels were observed with age and with the period of dialysis. Diurnal variations in the Epo levels revealed a significant increase after hemodialysis, and an acute reduction in hematocrit following massive hemorrhage raised the Epo levels up to 3,180 mU/ml. These findings indicate that the Epo levels in dialysis patients are inappropriately low for the severity of anemia and suggest that a negative feedback mechanism of the hematocrit on the Epo secretion may exist in uremic patients as well as in normal subjects and that the threshold for Epo secretion might be 'reset' at a low hematocrit level.

[Plasma beta-endorphin in patients on maintenance hemodialysis]

A sensitive and specific radioimmunoassay for beta-endorphin without gel filtration of plasma extracts has been developed by using newly raised antibody. The minimal detectable quantity was 5 pg, and ED 50 was 23 pg/ml. The crossreactivity of antibody with beta-lipotropin was 3.3%, but not showed crossreaction with other fragments of beta-lipotropin, beta-MSH and ACTH. The inter-assay coefficient of variation was 2.7% to 17.4%, and the intra-assay coefficient of variation was 4.5% to 26.4%, respectively. The mean recovery for unlabeled beta-endorphin added to plasma and extracted was 92.1% to 110.4%. Plasma levels of beta-endorphin in 40 normal subjects was 14.7 +/- 3.1 pg/ml and 14.8 +/- 1.1 pg/ml in 10 patients with chronic glomerulonephritis whose renal function was normal. There was no significant difference between the two groups. On the other hand, plasma levels of beta-endorphin in 16 patients on maintenance hemodialysis was significantly increased of 56.3 +/- 6.3 pg/ml than the other two groups. Physiological role of this high beta-endorphinemia in patients on maintenance hemodialysis still remains to be resolved.

Clinical significance of cerebral aneurysm in renovascular hypertension due to fibromuscular dysplasia: two cases in siblings

Two cases, in siblings, of renovascular hypertension caused by fibromuscular dysplasia (FMD) of the renal artery associated with cerebral aneurysms are reported. Both of the cases were found to have cerebral aneurysm, as well as multiple stenotic or occluded lesions in arteries such as renal, mesenteric, celiac, and internal carotid arteries. One case died of subarachnoid hemorrhage and the other case was successfully operated on for the aneurysm. This report suggests that FMD should be considered to be a systemic angiopathy including the cerebral artery, as well as the renal artery. Thus, cerebral angiography is recommended to detect the association with cerebral aneurysm, at least, in cases with multiple lesions of FMD. Occurrence of FMD in siblings also indicates that a genetic factor might be involved in the pathogenesis of FMD.

Immunoreactive prorenin and its profragment peptide are present in human juxtaglomerular cells

Although prorenin appears to be activated through the cleavage of its prosegment in the juxtaglomerular cells, the presence of prosegment peptide has never been demonstrated. We therefore studied prorenin in juxtaglomerular tumour cells, both by immunohistochemistry and by radio-immunoassay. Synthetic peptide covering the 14-carboxyterminal sequence of human renin prosegment was used to prepare both antibody and radiolabelled tracer. Intense immunostaining of prorenin was demonstrated in the tumour cells. By gel filtration, however, immunoreactive prorenin was shown to consist of two major components. The first peak, located at the elution position of activatable inactive renin, was regarded as prorenin. The other peak was located at an elution position with a smaller molecular weight, which was assumed to represent the profragment. These results suggest that both prosegment peptide and prorenin are present in the juxtaglomerular cells.

Hormonal and renal effects of atrial natriuretic peptide in patients with secondary hypertension

To investigate the involvement of atrial natriuretic peptide (ANP) in secondary hypertension, we examined hormonal and renal responses to ANP infusion (0.025 microgram/kg/min) in 27 patients with renal parenchymal hypertension, 10 with primary aldosteronism, 8 with renovascular hypertension, and 15 normotensive subjects. The preinfusion plasma concentration of ANP was significantly higher in patients with renal parenchymal hypertension (120 pg/ml, p less than 0.01) and in patients with primary aldosteronism (98 pg/ml, p less than 0.05) than in the normotensive subjects (40 pg/ml), but it was not greater than in the patients with renovascular hypertension (73 pg/ml, NS). In the patients with renal parenchymal hypertension, plasma ANP correlated negatively with creatinine clearance (r = -0.76, p less than 0.001). Mean blood pressure (-5%, p less than 0.01) and plasma aldosterone (-40%, p less than 0.001) decreased to a similar degree in the four groups during ANP infusion. However, an increase in urinary sodium excretion caused by ANP was higher in the hypertensive than in the normotensive patients (+250% vs. +70%, p less than 0.01) and correlated positively with mean blood pressure during ANP infusion (r = 0.47, p less than 0.001). The removal of adenomas in the patients with primary aldosteronism significantly lowered both plasma levels of ANP and cyclic guanosine 2',3'-monophosphate and reduced an increase in sodium excretion during ANP infusion, whereas the responses of blood pressure and plasma aldosterone to ANP infusion were not altered by the operation. Thus, these results suggest that elevated ANP secretion and increased natriuretic responses to ANP may modify the blood pressure and body fluid volume status in some types of secondary hypertension.

Extrarenal role of aldosterone in the regulation of blood pressure

To assess the hypothesis that aldosterone may have direct vasoconstrictive action, the acute effects of canrenoate potassium (Soldactone, S), an aldosterone antagonist, on hemodynamics and hormonal responses were determined before and after the intravenous administration of 2 mg/kg S in 11 patients with primary aldosteronism (PA), 9 patients with essential hypertension (EH), and 5 patients with renovascular hypertension (RVH). S caused a significant -12 +/- 2 mm Hg decrease in MBP in PA, -5 +/- 2 mm Hg in EH, and -4 +/- 1 mm Hg in RVH. Reduction in MBP was significantly higher in PA than in the others and there was a negative correlation between changes in MBP and basal PAC. The cardiac index did not change throughout the study in all groups, which led to a significant reduction in total peripheral resistance index (TPRI) in PA but not in the others. There was a significant correlation between changes in MBP and TPRI (r = 0.82, p less than 0.01). PRA did not change throughout the study, but PAC and cortisol were significantly elevated. There were no correlations between changes in MBP and hormonal responses. In conclusion, S resulted in a significant reduction of MBP mediated by a significant reduction of TPRI. These results suggest that aldosterone may have direct vasoconstrictive action and this extrarenal effect of aldosterone may be involved in the regulation of blood pressure.

Sites of action of beta-melanocyte stimulating hormone in aldosterone biosynthesis in the rat

The sites of action of beta-melanocyte stimulating hormone (beta-MSH) on aldosterone biosynthesis were studied using collagenase-dispersed adrenal glomerulosa cells from rats maintained on either normal or sodium-deficient diets for 2 weeks. Isolated cells were treated with a cyanoketone derivative (WIN 19,578) to isolate the early and late steps in aldosterone biosynthesis. WIN 19,578 (1 microM) completely blocked aldosterone production stimulated by sodium depletion, AII, ACTH, and beta-MSH. beta-MSH (1 microM) significantly stimulated pregnenolone production (early step) and the conversion of corticosterone to aldosterone (late step) in aldosterone biosynthesis. The effect of beta-MSH was similar to AII and ACTH. Sodium depletion enhanced the effect of beta-MSH only on the late step in aldosterone biosynthesis. In conclusion, beta-MSH stimulates both the early and late steps of aldosterone biosynthesis. These results suggest that beta-MSH or peptides containing beta-MSH may play a role in the regulation of aldosterone production.