Hypertensive glomerular damage as revealed by the expression of alpha-smooth muscle actin and non-muscle myosin

The aim of this study was to determine the phenotypic modulation in mesangial cells of glomeruli damaged by hypertension. Salt-loaded stroke-prone spontaneously hypertensive rats were untreated or treated with a calcium antagonist, manidipine (2 mg/kg/day) for eight weeks. In normotensive Wistar-Kyoto rats, alpha-smooth muscle actin was not expressed in any glomerular cells and a non-muscle myosin heavy chain isoform, SMemb, was slightly expressed in glomerular visceral epithelial cells. In the untreated hypertensive rats, the glomeruli showed sclerosis to various degrees and expressed alpha-smooth muscle actin and SMemb. Normal expression of SMemb in the epithelial cells disappeared. Notably, alpha-smooth muscle actin-positive fibroblast-like cells appeared in the interstitium, especially around the Bowman's capsules. Manidipine ameliorated the glomerulosclerosis and reduced the expression of alpha-smooth muscle actin in mesangial cells. In conclusion, the mesangial cells changed their phenotypes and expressed alpha-smooth muscle actin and SMemb in the glomeruli during the development of hypertensive renal damage. These phenotypically changed mesangial cells are considered to be activated and to produce various kinds of cytokines and extracellular matrix, which leads to glomerulosclerosis. Manidipine attenuated the glomerular damage and the phenotypic changes. The functional relevance of phenotypic changes in these cells should be elucidated in future studies.

Role of ouabain-like compound in the regulation of plasma aldosterone concentration in rats

A major biologically active Na,K-ATPase inhibitor in the mammalian circulation may be ouabain-like compound(OLC). We developed a population of immunized rats against ouabain to block the actions of circulating OLC. To investigate the roles of OLC in the regulation of aldosterone secretion and/or production, we measured plasma aldosterone concentration after a week of low salt diet. No significant changes in serum Na and K concentrations were observed in immune rats. The plasma aldosterone concentration was significantly decreased by 30% in 17 immune rats as compared with 11 control rats(control: 455 +/- 53, immune: 315 +/- 21 pg/mL, p < 0.05). These data indicate that chronic blockade of the circulating OLC significantly decreases plasma aldosterone concentration during salt depletion and suggest that endogenous OLC may play an important role in the regulation of aldosterone secretion and/or production.

Effects of intracerebroventricular administration of 6-hydroxydopamine on ouabain-like immunoreactivity in plasma and the hypothalamo-pituitary axis in rats

OBJECTIVE

To examine the role of central mechanisms on the production and release of an ouabain-like factor, the effects of intracerebroventricular injections of 6-hydroxydopamine on the tissue content and on the plasma level of the ouabain-like factor were determined in rats.

METHODS

The vehicle (0.1% ascorbic acid in 0.9% saline) and 6- hydroxydopamine (250 micrograms/rat) were injected into the left lateral ventricle in ether-anaesthetized Wistar rats. Hypothalamus, pituitary, adrenal and venous blood was sampled 24h and 7 days later. The procedure was repeated using another rat group 7 days later. Characteristics of immunoreactive ouabain-like factor were determined by a combination of high-performance liquid chromatography and a highly sensitive enzyme-linked immunosorbent assay for ouabain. The level of the ouabain-like factor in these tissues and in plasma extracts measured by the enzyme-linked immunosorbent assay was compared between the two groups receiving 6-hydroxydopamine and the vehicle.

RESULTS

Twenty-four hours after the intracerebroventricular injections of 6-hydroxydopamine, the ouabain-like factor level in the pituitary, hypothalamus and plasma had decreased significantly, whereas the ouabain-like factor level in the adrenal had not changed. The content of noradrenaline in the hypothalamus was also decreased markedly 7 days later and the content of ouabain-like factor in the pituitary remained low. On liquid chromatography the elution pattern of the ouabain-like factor in plasma and in tissue extracts coincided with that of authentic ouabain.

CONCLUSIONS

Intracerebroventricular treatments with 6-hydroxydopamine elicited decreases in ouabain-like factor contents in the pituitary, the hypothalamus and the plasma. These results suggest that the production and release of ouabain-like factor are closely associated with the brain, particularly the hypothalamus-pituitary axis, and that noradrenergic or dopaminergic neurons, or both, play a key role in this mechanism.

Nitric oxide release from kidneys of hypertensive rats treated with imidapril

To examine whether endothelial dysfunction in hypertension is reversible or not, we studied the effects of imidapril, an angiotensin-converting enzyme inhibitor, on nitric oxide release in stroke-prone spontaneously hypertensive rats (SHR) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. After a 4-week treatment with imidapril (1 or 10 mg/d SC) or vehicle, acetylcholine-induced vasodilation and nitric oxide release in the isolated kidneys were determined. Nitric oxide release was measured by a chemiluminescense assay. Imidapril lowered blood pressure in stroke-prone SHR in a dose-dependent manner. Untreated stroke-prone SHR exhibited significantly attenuated responses to acetylcholine (10(-8) mol/L) of both renal perfusion pressure (stroke-prone SHE 42 +/- 4% versus Wistar-Kyoto rats [WKY] 58 +/- 4% [mean +/- SE], P < .01) and nitric oxide release (stroke-prone SHR +7.6 +/- 2.1 versus WKY +29.7 +/- 9.7 fmol/min per gram of kidney wt, P < .01). Imidapril at 10 mg/d significantly increased acetylcholine-induced renal vasodilation and nitric oxide release in stroke-prone SHR (renal perfusion pressure, 56 +/- 3%; nitric oxide release, +27.1 +/- 6.4 fmol/min per gram of kidney wt; both P < .01 versus stroke-prone SHR treated with vehicle). On the other hand, imidapril neither decreased blood pressure nor changed nitric oxide release induced by acetylcholine in DOCA-salt hypertensive rats. Staining for endothelial nitric oxide synthase and brain nitric oxide synthase was clearly detected in the kidneys of both stroke-prone SHR and WKY, whereas staining intensity was weaker in DOCA-salt hypertensive rats. Inducible nitric oxide synthase immunoreactivity was barely noticeable in any type of rat. Thus, imidapril restored endothelial damage by pressure-dependent mechanisms. Most of the nitric oxide detected in the perfusate seemed to be derived from constitutive nitric oxide synthase.

Miller-Dieker syndrome due to maternal cryptic translocation t(10;17) (q26.3;p13.3)

We report on a 3-month-old girl with Miller-Dieker syndrome resulting from a maternal full-cryptic translocation t(10;17) (q26.3;p13.3) detectable only by using fluorescence in situ hybridization (FISH). Parental studies using FISH are crucial for genetic counselling in cases of Miller-Dieker syndrome with submicroscopic deletion at 17p13.3. In a family with a parental cryptic translocation and high recurrence risk, parental diagnosis using FISH is feasible.

Congenital hypomyelination neuropathy: decreased expression of the P2 protein in peripheral nerve with normal DNA sequence of the coding region

Congenital hypomyelination neuropathy (Lyon type) is characterized by a non-progressive clinical course and a histopathological formation of atypical onion-bulb. We have studied the immunohistochemical expression of the major peripheral myelin proteins including P0 protein, myelin basic protein (MBP) and P2 protein in three such patients. No significant difference was observed between the patients and the controls, as to the P0 and MBP staining. In contrast, P2 protein antiserum scarcely stained the patients' nerve fibers except for a few scattered adequately myelinated fibers. Assuming the pathogenetic contribution of the extremely decreased P2 protein to the disease, we investigated P2 protein gene by sequencing all coding regions but failed to detect any change in the nucleotide sequence. Further investigation including the analysis of promoter region of P2 protein gene is needed to elucidate the mechanism of congenital hypomyelination neuropathy.

Modulation of vascular calcium channel activity in response to acute volume expansion in rats

The mechanisms of the increased resistance in hypertension are still unclear. Several studies have indicated that the potential-sensitive Ca2+ channels (PSC) are altered in arteries isolated from hypertensive patients or animals. An expansion of body fluid volume may trigger local autoregulatory responses or may induce the release of humoral factors, either of which could increase systemic vascular resistance and cause volume-dependent forms of hypertension. We tested the hypothesis that volume expansion per se may cause the alterations of PSC similar to those seen in hypertension. For this, we examined the alterations of PSC in aortas from volume-expanded rats with the use of dihydropyridine-type Ca2+ channel activator, BayK 8644, in parallel with the changes in endothelium-dependent relaxation. Volume expansion was produced by a rapid intravenous infusion of saline (10% of body weight) over 30 min in rats. At the end of infusion, rats were killed and aorta removed for in vitro measurement of isometric tension. Relaxation to acetylcholine (10(-7)-10(-5) mol/L, % relaxation to 10(-7) mmol/L norepinephrine contraction) was not significantly changed. In contrast, contractile response to BayK 8644 (10(-9)-10(-6) mol/L, % response to 50 mmol/L KCl) was significantly enhanced in rats with volume expansion (12 control rats: 11.6 +/- 4.9%; 18 volume-expanded rats: 40.9 +/- 10.4% at 10(-6) mol/L, p < 0.05). These findings suggest that acute volume expansion could induce a similar enhanced vascular Ca2+ channel activity to that seen in hypertension in rats.

Stress-induced elevation of ouabainlike compound in rat plasma and adrenal

Recent observations demonstrate the presence of neurosteroids and their rapid increase in response to acute stress. In view of a steroidal nature of ouabainlike compound, we tested the hypothesis that ouabainlike compound may participate in a homeostatic response to acute stress. Male Wistar rats were subjected to acute stress by swimming in water (22 degrees C) for 10 minutes. The levels of ouabainlike compound in plasma, hypothalamus, pituitary, and adrenal at 10, 40, and 70 minutes (n = 8 for each) after the end of swim stress were compared with nonstressed control levels (n = 10). Ouabainlike compound was measured by a radioimmunoassay for ouabain. Plasma levels of corticosterone and catecholamines were also measured. Plasma corticosterone concentrations increased rapidly at 10 minutes (P < .01) and then declined. A trend for a rise in plasma catecholamines was found at 10 minutes. Adrenal levels of ouabainlike compound concomitantly increased at 10 minutes (P < .01, control: 58.9 +/- 5.9 pmol ouabain equivalents per gram; 10 minutes: 92.5 +/- 4.8; 40 minutes: 47.3 +/- 9.6; 70 minutes: 45.1 +/- 6.3). In contrast, the response of plasma ouabainlike compound was slow and doubled at 40 minutes (P < .01, control: 115 +/- 12 pmol ouabain equivalents per liter; 10 minutes: 132 +/- 23; 40 minutes: 226 +/- 53; 70 minutes: 117 +/- 16). Ouabainlike compound levels in hypothalamus and pituitary remained unaltered. These findings suggest that ouabainlike compound may function as a stress hormone.

A new adenosine subtype-1 receptor antagonist, FK-838, attenuates salt-induced hypertension in Dahl salt-sensitive rats

We investigated the effects of the adenosine type-1 receptor antagonist FK-838 on salt-induced hypertension in Dahl-Sea salt-sensitive (Dahl S) rats. Dahl S rats fed a high-salt (4% NaCl) diet for 4 weeks were treated with FK-838 or hydrochlorothiazide for 4 weeks and alterations in kidney function and morphologic changes were assessed. FK-838 attenuated the development of hypertension in Dahl S rats, and caused a decrease in aortic weight in a dose dependent fashion. The adenosine antagonist did not produce any detectable metabolic disturbance. The blood pressure reduction by FK-838 was associated with attenuation of glomerular and arterial injury in the kidney. The renal protective effect of FK-838 treatment was associated with a reduction of plasma renin activity and plasma aldosterone concentration. In contrast, the thiazide diuretic, which produced almost the same blood pressure reduction as FK-838, did not attenuate renal damage. These data indicate that adenosine A1 receptor antagonism reduces salt-induced hypertension and the consequent renal injuries.

Role of tissue factor in disseminated intravascular coagulation

We examined plasma antigen levels of tissue factor (TF) in 95 cases of disseminated intravascular coagulation (DIC), to investigate the role of TF in DIC. A significant elevation of plasma antigen levels of TF was observed in cases of DIC associated with cancer. However, no such significant elevation was observed in cases of DIC associated with acute promyelocytic leukemia (APL), acute leukemia except APL, blastic crisis of chronic myelogenous leukemia, non-Hodgkin lymphoma (NHL), sepsis or fulminant hepatitis. No significant elevation of TF was observed in patients without DIC, except 4 cases of cancer who developed DIC thereafter. Plasma antigen levels of TF were higher in both cases of DIC with renal failure and chronic renal failure without DIC than its levels in those without renal failure. Therefore, plasma antigen levels of TF in DIC patients with renal failure were considered to be carefully estimated. The levels of TF were decreased with the clinical improvement in some cases of DIC but were further increased or remained at high levels in patients who showed no improvement of DIC. Thus, plasma antigen levels of TF is an important marker to predict the development and/or prognosis of DIC, especially in patients with cancer.

[Aplastic anemia associated with ovarian bleeding]

A 22-year-old female was admitted on June 19, 1993 with pancytopenia. Aplastic anemia was diagnosed and she was treated with anti-thymocyte globulin. After one month, she started to feel abdominal pain. Her platelet count was 1.3 x 10(4)/microliters at that time. Computed tomography revealed vast accumulation of blood in the abdomen and pelvis. A total of 1,000 ml blood was obtained from the right ovarium and she underwent right partial oophorectomy. Although ovarian bleeding is rarely reported in aplastic anemia, we should always keep in mind this possibility when abdominal pain occurs in a female patient.

Possible linkage between renal injury and cardiac remodeling in Dahl salt-sensitive rats treated with the calcium channel antagonist benidipine

Interest in cardiovascular protection by calcium channel antagonists has grown over the past decade. We investigated the prevention of cardiac remodeling and renal injury by the long-acting calcium channel antagonist benidipine using 12 week-old Dahl salt-sensitive (Dahl S) rats fed a high-salt (4% NaCl) diet. Six-week benidipine treatment (10 mg/kg chow) decreased systolic blood pressure by 22% in Dahl S rats. This blood pressure reduction was associated with decreases in cardiac mass and weight of the aortic wall. Collagen content in the left ventricle tended to decline with benidipine treatment. In addition, glomerular filtration rate increased by 33% and arterial and glomerular lesions improved morphologically with this treatment. Regression of cardiac mass and collagen content in the left ventricle was due mainly to blood pressure reduction; however, collagen content in the low-pressure right ventricle was not only related to systemic blood pressure but to the severity of renal lesions. These data suggest that the calcium channel antagonist benidipine attenuates cardiac and renal injury in hypertensive Dahl S rats, and that part of the cardiac hypertrophy is due to a non-hemodynamic mechanism that might be responsible for, or be a consequence of, the lesions in the kidney.

Perinatal intracranial hemorrhage due to severe neonatal alloimmune thrombocytopenic purpura (NAITP) associated with anti-Yukb (HPA-4a) antibodies

Neonatal alloimmune thrombocytopenic purpura (NAITP) is one of the causes of thrombocytopenia in the newborn period. The thrombocytopenia is caused by maternal transplacental antiplatelet alloantibodies. We report a case of NAITP in a newborn infant having subarachnoid hemorrhage. Examination of platelet antibodies revealed anti-Yukb, that is, human platelet antigen (HPA)-4a incompatibility. Cranial ultrasound and brain magnetic resonance imaging revealed subarachnoid hemorrhage in the temporal region inferior to the cephalohematoma. The lesion seemed to have been sustained during delivery. The patient was treated with high-dose gamma-globulin and several transfusions of random donor platelets and showed a good clinical course. This is the second reported case of NAITP associated with the Yuk antigen system having intracranial hemorrhage.

[Experimental changes in BDNF- and NT-3-like immunoreactivities in the spinal cord following its transection]

Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are neurotrophic factors involved in the neurotrophin family. However, while their biological activities on cultured neurons and their distribution have been reported, their functions in the central nervous system including the spinal cord are still unknown. We have recently developed antibodies to BDNF and to NT-3 synthetic peptides with different amino acid sequences as tools to visualize these molecules in in vivo tissue. Each antibody was specific to either BDNF or NT-3. Using these antibodies, we investigated the distribution of BDNF- or NT-3-like immunoreactivities (LI) in the spinal cord following transection in rats. In Group with an uninjured spinal cord as control, both BDNF-LI and NT-3-LI were localized in the gray matter, and particularly in the motor neurons of the ventral horn, and in some axons and glial cells of the white matter. In Group after transection of the spinal cord as a model of spinal injury, the motor neurons in the spinal cord, were strongly stained by anti-NT-3 antibodies and less strong by anti-BDNF antibodies at 3 weeks after injury. In the gray matter at 4 weeks after injury, astrocyte-like cells were markedly stained with anti-BDNF antibodies These findings indicate that in the spinal cord after injury, the biosynthesis of BDNF was upregulated in a different manner from that of NT-3 and that BDNF and NT-3 were both involved in the repair mechanisms, directing the amelioration of the spinal cord injury.

The effect of dietary protein levels on the responses of the taste nerve to sodium chloride in spontaneously hypertensive rats (SHRs)

The present study was undertaken to clarify the effect of dietary protein level on the response of the taste nerve to NaCl solutions in spontaneously hypertensive rats (SHRs). The results showed that the taste sensitivity to NaCl in SHRs fed a 5% whole-egg protein diet for 3 weeks was significantly lower than in those fed a 15% protein diet. This observation suggests that chronic feeding of a low-protein diet causes an impairment of salt-taste reception or subsequent transduction.

Effects of intracerebroventricular infusion of Fab fragments of digoxin antibody (Digibind) on development of reduced renal mass-saline hypertension in rats

To clarify the role of brain ouabain-like compound in reduced renal mass-saline hypertension, we examined the effects of intracerebroventricular infusion of the Fab fragments of antidigoxin antibody (Digibind) on the change in blood pressure of saline-drinking subtotally nephrectomized rats. Twenty male Wistar rats weighing 250 g each underwent subtotal nephrectomy. Two groups of 10 rats received intracerebroventricular infusion of Digibind (20 mg/ml) or normal sheep IgG (20 mg/ml) at a rate of 0.5 microliters/h for 11 days. All rats began to drink 1% NaCl solution after two days of infusion. Systolic blood pressure was measured by the tail-cuff method on days 2, 6 and 9 of infusion. Two groups of saline-drinking rats with reduced renal mass developed hypertension. However, systolic blood pressure was significantly higher in Digibind-infused rats than in IgG-infused rats (day 2, 144 +/- 3(SEM) vs. 133 +/- 1 mmHg, p < 0.05; day 6, 161 +/- 4 vs. 151 +/- 2 mmHg, 0.05 < p < 0.1, day 9, 181 +/- 8 vs. 155 +/- 2 mmHg, p < 0.05). In spite of similar renal dysfunction, plasma aldosterone concentrations, and plasma OLC levels, the accelerated increase in blood pressure was accompanied by a significantly impaired pressure-natriuresis relationship (0.089 +/- 0.013 vs. 0.131 +/- 0.013 mmol/day/mmHg, p < 0.05). These results indicate that chronic intracerebroventricular infusion of Digibind augmented reduced renal mass-saline hypertension in rats and suggest that brain ouabain-like compound may play a protective role against the elevation of blood pressure, at least in this model of hypertension.

Isolation and characterization of the cDNA for pea chloroplast SecA. Evolutionary conservation of the bacterial-type SecA-dependent protein transport within chloroplasts

We report here the isolation of the cDNA for pea chloroplast SecA. Pea SecA encodes a polypeptide of 1,011 amino acids and shows high sequence similarity with cyanobacterial SecA. Pea SecA was synthesized as a larger precursor and was imported into isolated chloroplasts in vitro. The purified pea SecA, which was expressed in Escherichia coli cells, stimulated the in vitro import of the 33 kDa protein of the oxygen-evolving complex into thylakoids. These results indicate that higher plant chloroplasts contain a bacterial-type SecA protein-dependent system for the intraorganellar protein transport into thylakoids.

Participation of endogenous atrial natriuretic peptide in the regulation of urinary protein excretion in experimental diabetic rats

1. In order to determine whether atrial natriuretic peptide might play a role in the development of glomerular hyperfiltration in diabetes mellitus, we examined the effects of administration of glucose, albumin, atrial natriuretic peptide and an atrial natriuretic peptide receptor antagonist on renal function in rats with streptozotocin-induced diabetes mellitus and vehicle-treated control rats. 2. Four weeks after treatment, rats with diabetes mellitus had a higher mean plasma atrial natriuretic peptide concentration than controls [152 +/- 5 (SE) versus 115 +/- 6 pg/ml, P < 0.01] and a higher glomerular filtration rate (3.3 +/- 0.1 versus 2.7 +/- 0.2 ml min-1 kg-1, P < 0.05). 3. Infusion of albumin or glucose caused significant increases in atrial pressure, plasma atrial natriuretic peptide concentration and urinary excretion of sodium and protein in both groups of rats. 4. Increasing plasma atrial natriuretic peptide concentration by 60% via atrial natriuretic peptide infusion increased urinary excretion of sodium and protein in both control rats and rats with diabetic mellitus. 5. Administration of the atrial natriuretic peptide receptor antagonist HS-142-1 to diabetic rats resulted in diminished urinary excretion of both sodium (-61 +/- 14%, P < 0.02) and protein (-51 +/- 17%, P < 0.05). These changes were associated with a significant reduction in glomerular filtration rate (-32 +/- 11%, P < 0.05) and urinary cGMP excretion (-40 +/- 14%, P < 0.05). No significant effects of HS-42-1 on renal function were observed in control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma adenosine concentrations are elevated in Dahl salt-sensitive rats

We measured plasma levels of adenosine in Dahl salt-sensitive rats (DS) and Dahl salt-resistant rats (DR) to examine the potential role of adenosine in cardiovascular regulation in this type of hypertension. Plasma adenosine concentrations were significantly higher in DS than in DR. The NaCl content in the diet did not affect plasma adenosine concentration in either DS or DR. Significant positive correlation was found between adenosine concentrations and systolic blood pressure when the data for DS and DR were analyzed together. These results suggest that adenosine may play an important role in the pathophysiology of hypertension in DS.

Modulation of the levels of ouabain-like compound by central catecholamine neurons in rats

Catecholamine regulates the Na+,K(+)-ATPase activity in the central nervous system and the Na+,K(+)-ATPase has been shown to have endogenous ligands (ouabain-like compound; OLC). To examine the relationship between OLC and central adrenergic neurons, we evaluated the effects of central sympathectomies with intracerebroventricular (i.c.v.) injection of 6-hydroxydopamine (6-OHDA; 250 micrograms) on brain and plasma OLC levels and brain catecholamine levels. In centrally sympathectomized rats, hypothalamic OLC content and plasma OLC level were significantly decreased by 90% (P < 0.01) and 70% (P < 0.01), respectively, in accordance with reduced brain norepinephrine content compared with control rats pretreated by i.c.v. injection of vehicle (ascorbic acid). On the other hand, peripheral sympathectomy with a similar manner did not affect plasma OLC level at all. These findings suggest that central adrenergic neurons may be involved in the synthesis and/or release of circulating OLC.

[Clinical analysis of 130 cases of Siberian silicosis]

One hundred thirty patients with Siberian silicosis occurring under exposure to large amounts of dust at labor in a siberian mine were analyzed for 67 clinical and 122 laboratory data. Eighty-eight of 130 patients are now alive, but 42 have already died. When they started work, 122 of the patients were under thirty years of age. The duration of work was 7 to 12 months for 17 patients, 13 to 18 for 43, and 19 to 24 for 40. Seventy-six of 99 patients were initially diagnosed with lung tuberculosis and 23 with silicosis. Almost all patients have complained of respiratory symptoms such as shortness of breath, cough, sputum, and cyanosis. All of the pulmonary function tests including %VC, FEV1.0/FVC, V25/height, RV, TLC, and DLco showed abnormal values. The chest roentogenograms showed 3 of type 1, 22 of type 2, 55 of type 3, and 124 of type 4. Of 124 type-4, large opacities, 84 were type A, 28 B, and 12 C. Of 416 small opacities, 144 were type P, 191 Q, and 81 R. The complications and secondary changes that appeared with progression of the disease were lung emphysema, hilar and mediastinal lymphnode enlargement, egg shell calcification in lymphnode, and bulla or bleb.