Renal vascular walls in patients with preeclampsia superimposed on essential hypertension.

This study was performed to clarify the relationship between changes in contractile proteins in renal vascular walls and the prognosis of hypertension during pregnancy. Twenty preeclamptic patients underwent renal biopsies after delivery and were divided into the following three groups: group I, patients with persistent hypertension after delivery (n = 7; mean age, 34.8 +/- 1.4 years [SE]); group II, patients who became normotensive after delivery and hypertensive again during follow-up (n = 5; mean age, 34.8 +/- 1.6 years), and group III, patients who became normotensive after delivery (n = 8; mean age, 28.0 +/- 1.0 years). We also examined age-matched healthy controls (group IV; n = 7; mean age, 34.9 +/- 1.5 years). Renal biopsy specimens were immunohistochemically stained by the avidin-biotinylated peroxidase complex method using antimonoclonal smooth muscle cell myosin heavy chain isoform antibodies (SM-1, SM-2) and antimonoclonal alpha-smooth muscle cell actin antibody (actin). We estimated and semiquantitatively scored the degree of staining in each section. In interlobular arteries, SM-1, SM-2, and actin staining in group I were significantly reduced compared with group IV (SM-1, SM-2, P: < 0.05; actin, P: < 0.01). In afferent arterioles (Afs), SM-1, SM-2, and actin staining were reduced in group I. SM-2 staining in group I was significantly reduced compared with the other three groups (versus group II, P: < 0.05; versus groups III and IV, P: < 0.01). These findings suggest that phenotypic changes in vascular smooth muscle cells (especially the disappearance of SM-2 in Afs) reflect the stage of underlying essential hypertension and can predict from the change in hypertension during pregnancy whether it will persist after delivery.

An ultrastructural study of p75 neurotrophin receptor-immunoreactive fiber terminals in the reticular thalamic nucleus of young rats.

The reticular thalamic nucleus (RT) receives cholinergic fibers from both the basal forebrain and the brainstem. Recent studies have shown that the p75 neurotrophin receptor (p75NTR) is synthesized in cholinergic neurons in the basal forebrain but not in those in the brainstem. In this study, to identify cholinergic fibers originating from the basal forebrain, we used a monoclonal antibody against p75NTR (192-IgG) and characterized the ultrastructure of the immunoreactive fiber terminals in the rostral part of the RT in 3-week-old rats. Light microscopy revealed that p75NTR-immunoreactive fine fibers and varicosities were distributed throughout the nucleus. From electron micrographs, three types of labeled terminals were identified. The first type of labeled fiber terminals (63 out of 106) was consistently small, contained densely packed vesicles, and established asymmetrical synaptic contacts with heavy and bushy postsynaptic thickening on distal dendritic profiles; the second type (18 out of 106) established asymmetrical synaptic contacts with very slight postsynaptic thickening; and the third type (25 out of 106) of labeled terminals contained pleomorphic vesicles and established symmetrical synaptic contacts with more proximal dendritic surfaces than the first two types. In addition to the above, labeled dendritic profiles receiving non-labeled asymmetrical and symmetrical synaptic contacts were identified. These findings suggest that the basal forebrain cholinergic system establishes a variety of synaptic connections in the RT and influences cortical activity indirectly via thalamocortical pathways, as well as via direct projections to the cortex.

Immunohistochemical study of endothelin-1 in preeclamptic nephropathy.

Whether the serum levels of endothelin, a vasoconstrictive peptide produced in the endothelial cell, increase in preeclamptic patients is still controversial. We performed immunohistochemical studies to observe the changes in endothelin-1 (ET-1) in preeclamptic kidney tissues. The monoclonal anti-human ET-1 antibody (Yamasa, Japan) and anti-von Willebrand factor (vWF, Dako, Denmark), a marker of endothelial cells, were used for the studies by the strepto-avidin-biotin peroxidase method (ABC-POD Kit, Wako, Japan). Twenty-nine patients and 12 normal controls were divided into four groups. The preeclamptic group included 14 patients diagnosed with preeclampsia by clinical symptoms of hypertension, proteinuria, and edema occurring in late pregnancy and as having preeclamptic nephropathy. They underwent renal biopsy 16.7 +/- 1.0 (mean +/- SEM) days after delivery. The nephrotic group comprised 10 normotensive nonpregnant patients with nephrotic-range proteinuria examined through biopsy before treatment (six cases of minimal change, two of focal segmental glomerulosclerosis, one of membranous nephropathy, and one of IgA nephropathy). The pregnant women with preexisting glomerular disease group included five pregnant women with normal renal function who were normotensive and had no increase in the amount of proteinuria throughout pregnancy. They underwent renal biopsy 10.8 +/- 2.9 days after delivery (two cases of membranous nephropathy, one of focal segmental glomerulosclerosis, one of thin basement membrane disease, and one of non-IgA mesangioproliferative glomerulonephritis). The normal kidney group comprised 12 healthy tissue samples taken from nephrectomized kidneys (five cases of renal cell carcinoma, one case of lipofibrosarcoma, and six cases of kidney transplant donors). In these four groups, ET-1 and vWF showed equally positive staining in small arteries. VWF also showed positive staining in arterioles and peritubular capillaries in all groups. Although the glomeruli showed positive staining with ET-1 along the capillary walls in the normal group and the nonpregnant nephrotic group, they showed very weak or negative results in the preeclamptic group. Moreover, gravida with underlying glomerular disease without superimposed preeclampsia also showed negative findings of ET-1 in the glomeruli. The glomeruli in the four groups showed positive findings, with vWF readings the same as in the controls. These results indicate that the production of ET-1 in the glomerular endothelial cells decreases in cases of both preeclampsia and normal pregnancy, and the condition may be caused by pregnancy itself.

A case report of nephrotic syndrome associated with rifampicin therapy.

We describe nephrotic syndrome occurring in a 53-year-old male patient on continuous rifampicin (RFP) therapy for pulmonary tuberculosis. After the pulmonary tuberculosis was improved by chemotherapy that included RFP, administration of Isoniazid and RFP was continued. After 16 weeks, he suddenly developed nephrotic syndrome, but never developed acute renal failure. He was admitted to hospital and renal biopsy was performed revealing minor glomerular abnormalities and few interstitial changes in light microscopy. No positive immunofluorescent microscopic findings were obtained without fibrinogen. Thus, minimal change nephrotic syndrome (MCNS) was diagnosed. In contrast, electron microscopy showed several injurious glomerular changes, such as the elevation of the endothelial layer, local widening of the subendothelial space which was filled with fine granular or fibrillar materials, irregularity of the endothelial investment, swelling or shrinkage of the endothelial cells, compatible with those seen in many diseased conditions supposedly caused by clinical or subclinical localized intravascular coagulation. Discontinuation of RFP administration completely relieved the patient of MCNS with the aid of predonisolone therapy. Thus, this patient might not have been a case of incidental, but rather drug (RFP)-induced MCNS.

A single Ser-180 mutation desensitizes feedback inhibition of the phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthetase in Escherichia coli.

The Escherichia coli phenylalanine-sensitive DAHP (3-deoxy-D-arabino-heptulosonate 7-phosphate) synthetase (aroG product) is one of the DAHP synthetase isozymes that catalyze the first committed step in the biosynthesis of aromatic amino acids and vitamins. Through target-directed mutagenesis of the cloned aroG on a plasmid vector, followed by screening of phenylalanine-resistant colonies, we isolated a clone (pG908) showing feedback-insensitive mutation of DAHP synthetase. The mutations were identified as a T-->A mutation at nucleotide 22, and a C-->T mutation at nucleotide 539, causing a Leu-8 to Ile-8 mutation and a Ser-180 to Phe-180 substitution, respectively. The resulting enzyme exhibited comparable enzymatic activity to the wild type, but the degree of feedback inhibition had declined from approximately 60% to less than 10% in the presence of 20 mM phenylalanine in the assay medium. Replacement of Ile-8 by Leu, and substitution of Phe-180 with Ser, Asn and Cys, using site-directed mutagenesis, demonstrated that Ser-180 is a critical residue in the feedback inhibition of AroG. The result suggests that the major role played by Ser-180 may not involve a simple charge-size effect in the Phe-binding site of the enzyme molecule, but rather may involve more complicated molecular interactions occurring in the feedback inhibition mechanisms.

FSGS-like lesions in pre-eclampsia.

Renal-biopsy specimens taken from pre-eclamptic patients are associated sometimes with focal-segmental glomerular sclerotic lesions (FSGS-like lesions) that closely resemble those of primary focal-segmental glomerulosclerosis. We studied a series of 60 sections from each of 19 cases of "pure" pre-eclampsia by light microscopy. Group I comprised 13 patients with FSGS-like lesions in their glomeruli, group II comprised 6 patients without such lesions. FSGS-like lesions were observed in 20.7 +/- 4.6% of glomeruli in group I. Epithelial droplets were observed in 12 of 13 cases in group I, but only one of 6 cases in group II. The incidence of granulated glomerular epithelial cells was significantly higher in group I (p less than 0.0005). The double contour of the basement membrane was more severe in group I than in group II (p less than 0.03). The percentage of glomeruli with FSGS and the number of weeks during which proteinuria of greater than or equal to g/day continued after delivery were positively correlated (r = 0.76, p less than 0.0002). We also found a significant positive correlation between the percentage of glomeruli with FSGS and the amount of proteinuria at delivery and biopsy (r = 0.66, p less than 0.003; r = 0.51, p less than 0.03). However, proteinuria disappeared in all patients. Three of them had successful second pregnancies. We consider that FSGS-like lesions can occur during pregnancy in "pure" pre-eclamptic patients but the lesions may not be progressive. We also suggest that proteinuria and epithelial cell change may be closely related with such lesions.

[A renal biopsy study in pre-eclampsia: clinical-pathological correlations in 20 cases].

Twenty cases of pre-eclamptic toxemia were examined clinicopathologically. Twelve primipara and 6 multipara underwent renal biopsy at 1-24 (3.5 +/- 5.4, mean +/- SD) weeks after delivery. Specimens were examined by light and electron microscopy and immunofluorescence. Their mean blood pressure at delivery was 177.0 +/- 19.4/116.3 +/- 10.2 mmHg, proteinuria was 9.5 +/- 8.4 g/day. Follow-up period was 23.0 +/- 19.3 months after delivery. The severity of double contour of the glomerular basement membrane and mesangial interposition were correlated with the amount of proteinuria at biopsy (r = 0.40, p less than 0.05, r = 0.51, p less than 0.05, respectively). Proteinuria disappeared in all cases after delivery. The length of the hypertensive period after delivery correlated with the severity of glomerular lesions (r = 0.63, p less than 0.05), but did not correlated with the severity of vascular lesions. All patients became normotensive within three months after delivery. No patients showed microhematuria during pregnancy or after delivery.

Actin filament alterations in glomerular epithelial cells of adriamycin-induced nephrotic rats.

The alterations of actin filaments in the glomerular epithelial cells of adriamycin-induced nephrotic rats were studied by electron microscopy and immunohistochemistry using both of the peroxidase-antiperoxidase and avidin-biotin methods. After the administration of adriamycin, the glomerular epithelial cells showed cell swelling, deformation of cell shape, vacuole formations, retraction or fusion of foot processes, detachment of the plasma membrane from the glomerular besement membrane (GBM), and an increase of cellular organelles. In parallel with these alterations, abnormal distribution of intracytoplasmic microfilaments of 5-6 nm in diameter was observed, which formed clusters, particularly gathering densely along the plasma membrane of the fused foot processes that abutted the GBM. Immnohistochemically, actin was demonstrated on the site of the above described filaments. The above results suggest that actin filaments may closely relate to the morphological maintenance of the glomerular epithelial cells and to their function as well.

Distribution of actin in mesangial cell of rat glomerulus.

The localization of actin in the renal glomerulus of normal and streptozotocin (SZ) or aminonucleoside (AN) administered rats was studied by immunofluorescent and electron microscopy. The immunofluorescence (IF) for actin in normal rats showed a fine granular mesangial pattern, but the intensity was weak. An increase in positivity and an enlargement of the distribution of IF were observed in both SZ and AN administered rats, and the pattern of staining was still mesangial. Under an electron microscope, the mesangial cells showed an increase in number of microfilaments of 5 nm in diameter as well as in other cellular organelles, such as rERs and free ribosomes. These results suggest that the IF-positive substance for actin in the mesangium and the microfilaments observed in the mesangial cells by electron microscopy are identical with each other, i.e. actin filaments. Further, the mesangial cells may react by stimulation from injurious agents, such as SZ or AN, to increase the amount of actin as well as the number of other cellular organelles.