[The role of ultrasonography and biopsy following kidney transplantation]

Several complications can occur during both the early and late postoperative periods after kidney transplantation. The methods used to follow up 575 kidney transplanted patients, (transplantations performed between October 1979 and November 1997) in the early (within 6 weeks) and late postoperative periods have been assessed. The diagnostic value of core biopsies and ultrasound examinations, the prevalence of complications, and the applicability of the diagnostic tools in the evaluation of the graft status and viability were analyzed. In the early postoperative period, graft rupture occurred more frequently after biopsy than in the late period (7.4% vs 0.82%), this leading graft loss in 18 of 20 cases. The sonographically diagnosed morphologic and functional changes were also analyzed. Sonography proved a very accurate method for the detection of perirenal fluid collections and masses and severe vascular complications. The data demonstrated that biopsy is indicated in the early postoperative period when the result of sonography is doubtful. In the late postoperative period, biopsy should be performed in every case.

Mitochondrial mutation as a probable causative factor in familial progressive tubulointerstitial nephritis

Renal biopsy of two children and a maternal relative, diagnosed with severe progressive tubulointerstitial nephritis, has shown the presence of distorted mitochondria. Mitochondrial DNA from the blood of these patients was analysed. No major deletions were found, but an A to G mutation was detected in position 5656. It is proposed that this mutation might play a causative role in the renal disease of the patients.

Quantitative ultrastructural study of afferent and efferent arterioles in IgA glomerulonephritis and benign nephrosclerosis

Arteriolosclerosis frequently occurs in IgA nephritis (IgAN), and it is the hallmark of benign nephrosclerosis (BNS). The quantitative ultrastructure of juxtaglomerular arterioles is not known in these disorders. We examined afferent and efferent arterioles in renal biopsies from 25 adult patients with IgAN (hypertension at biopsy: 14 patients) and 9 patients with BNS. Six age-matched living renal transplant donors acted as controls. A systematic independent sample of profiles was obtained in thin sections taken at predetermined levels. The thickness of the media (myomedial cells plus the matrix) and the thickness of the medial matrix were estimated stereologically. From these estimates, the matrix/myomedia ratio was calculated. In IgAN with normotension or hypertension, the afferent media and its compartments did not exhibit significant thickening compared with the controls, whereas in BNS the afferent media and its layers were markedly and significantly thickened. The efferent media in IgAN and BNS displayed mild and significant thickening, with significant thickening of the matrix in BNS and IgAN with normotension. The matrix/myomedia ratio was not altered significantly in any group. The results indicate that the afferent arterioles are not the main sites of IgAN-related arteriolosclerosis, that arteriolosclerosis in IgAN and arteriolosclerosis in BNS are different lesions, and that increased efferent arteriolar thickness, demonstrated here for the first time in IgAN and BNS, might be a manifestation of angiotensin II-mediated autoregulatory efferent vasoconstriction exerted to maintain the glomerular filtration pressure.

Acute tubulointerstitial nephritis: phenotype of infiltrating cells and prognostic impact of tubulitis

The prognostic impact of tubulitis and the phenotype of the infiltrating cells in the tubules were studied in ten percutaneous renal biopsies from six patients with acute tubulointerstitial nephritis (ATIN). The inflammatory cell subsets in the tubules and interstitium (CD3+, CD4+, CD8+, CD20+, CD45RO+, CD56+, CD57+, CD68+ and TIA-1+ cells), the expression of vimentin and the proliferation-associated antigen Ki-67 by cortical tubular cells, and the grade of tubulitis, interstitial infiltration and fibrosis were analysed. Cytotoxic injury to tubular cells in the vicinity of tubular-wall-localized lymphocytes was studied ultrastructurally. ATIN was drug-induced in three patients, related to Legionella infection in two and idiopathic in one patient. Four patients recovered, one with reduced renal function. Two patients developed end-stage renal disease. CD8+ and CD4+ lymphocytes, and a smaller number of macrophages, infiltrated the tubules. The predominant lymphocyte subset in the tubules was the same as in the interstitium. Cytotoxic injury to tubular cells was not seen electron microscopically. The tubular cells exhibited increased proliferative activity and expressed vimentin, indicating non-specific tubular damage. The cell subset, the severity of tubulitis, and the tubular expression of vimentin were not related to outcome. The main prognostic factor was the severity of the interstitial fibrosis. Tubulitis in ATIN may be a harmless non-immune reaction, mediated by tubular expression of cytokines, together with adhesion and other molecules.

Tubulitis in primary vascular and glomerular renal disease

A semiquantitative light microscopic study of 274 renal biopsy and 12 nephrectomy specimens was carried out to assess the frequency and severity of tubulitis (mononuclear leukocytes in the renal tubular wall) in all common glomerular diseases, diabetic nephropathy, renal amyloidosis and renal artery stenosis. The extent of interstitial inflammatory infiltrates and severity of interstitial fibrosis were also graded. Tubulitis was 1) frequent in crescentic glomerulonephritis (GN) with pauci-immune, linear and granular immune deposits, renal artery stenosis, diabetic nephropathy, lupus GN of WHO type IV, and IgA GN; 2) rare in minimal change and idiopathic membranous nephropathy; 3) usually severe in crescentic GN and renal artery stenosis; and 4) predominantly located in atrophic tubules in renal artery stenosis, diabetic nephropathy and IgA GN. The most important parameter for the grading of tubulitis was interstitial infiltration. However, no correlation was found between the grades of tubulitis, interstitial infiltrates and interstitial fibrosis in crescentic and lupus GN. It is suggested that renal ischemic injury, by eliciting expression of proinflammatory cytokines and neo-antigens in the tubulointerstitial space, might play a role in the development of tubulitis in vascular and glomerular renal diseases.

[Comparative analysis of ultrasonic studies, histopathological data and clinical parameters in dysfunctioning renal transplantation]

The correlation of B mode and Doppler sonographic parameters and diagnoses established by histological examination of graft biopsies, nephrectomies and clinical data are discussed. 48 histological samples from 36 patients were reevaluated. The maximum interval between sonography and histology was 36 hours. The Banff classification criteria were used during histological examinations. Doppler examination evaluation was based on the resistance index (RI). Reproducibility was controlled by means of intra- and interobserver variability in 10 patients. RI values higher than 75% were regarded as abnormal. On the basis of these observations and the literature data specific sonographic features can be detected in renal artery occlusion and renal vein thrombosis. In pyelonephritis, dilatation of the collecting system was frequent. No morphological changes were detected in cyclosporin-A nephrotoxicity and the Doppler signs were not characteristic for this disease. No differentiation was found between acute rejection and acute tubular necrosis. The noninvasive duplex sonographic examinations can provide very important information regarding the flow situation of a transplanted kidney. In some cases a definitive diagnosis can be achieved, but in other cases biopsy is the method of choice.

Segmental localization and quantitative characteristics of tubulitis in kidney biopsies from patients undergoing acute rejection

The term tubulitis denotes infiltration of the renal tubular epithelium by mononuclear cells. Tubulitis is one of the most reliable signs of acute renal allograft rejection. However, its segmental localization and quantitative characteristics are not precisely known. To investigate this question, formalin-fixed kidney biopsy specimens from 15 patients with transplanted allografts undergoing acute rejection were studied stereologically by identifying cortical tubules with segment-specific markers. The periodic acid-Schiff reaction, peanut lectin, and antibodies against Tamm-Horsfall protein and epidermal cytokeratins, all applied to the same section, were used to identify the profiles of proximal tubules (PTs), distal convoluted tubules (DCTs), distal straight tubules (DSTs), and the cortical collecting system (CCS, connecting tubules and cortical collecting ducts), respectively. Two parameters, the relative intrasegmental length and the average intensity of tubular damage, were determined to describe the degree of tubulitis quantitatively. Tubulitis was most prominent in the DCTs, followed by the CCS. The average intensity of tubulitis was lowest in the DSTs. The results indicate that the PTs are not the main site of tubulitis, despite the fact that they are regarded primary targets of the rejection response.

Development of chronic renal failure in patients with multiple myeloma

Glomerulotubular disconnections at the immediate postglomerular segment of the proximal tubules, accounting for an impaired renal function, were demonstrated recently in several chronic nonglomerular renal disorders. To analyze the glomerulotubular junctions in Bence Jones cast nephropathy, paraffin blocks from the kidneys of nine deceased patients with myeloma and chronic renal failure on whom autopsies were performed were studied in serial sections. Kidneys from seven deceased patients without renal disease on whom autopsies also were done served as controls. For stereological estimations, the percentages of patent and sclerosed glomerular profiles, the relative volume fractions, and the absolute volumes of the interstitium, tubules, and glomeruli were determined. In Bence Jones cast nephropathy, 96% of the glomerular profiles were patent, and the reconstruction of randomly chosen glomerulotubular junctions revealed that 84% of the patent glomeruli had normal tubular connections. There was an increased relative interstitial volume (fibrous tissue) and a decreased relative tubular volume. The absolute values indicated severe interstitial fibrosis, but not tubular atrophy. The results show that in contrast with other chronic nonglomerular nephropathies, chronic renal failure in Bence Jones cast nephropathy does not result from nephron disconnection at the immediate postglomerular segment of the proximal tubules. The main factor responsible for the decrease in renal function appears to be the progressive severe fibrosis of the interstitium.

Postcapillary venule-like transformation of peritubular capillaries in acute renal allograft rejection. An ultrastructural study

To describe ultrastructural changes in renal peritubular capillaries during acute allograft rejection, biopsy specimens from five allografts with acute rejection were studied electron microscopically and compared with control specimens. The thickness, cross-sectional area, and luminal circumference of capillary endothelium were estimated morphometrically. Thickening of endothelial cells, loss of fenestration, increase in endothelial cell organelles, increased adherence and passage of lymphocytes and monocytes, and defects in the endothelial lining were demonstrated. The luminal circumference representing the size of the capillary was not changed. A balloonlike fragmentation of endothelial cells was sometimes observed around lymphocytes, suggesting cytotoxic injury to capillaries. The observations indicate that during rejection-induced endothelial activation, peritubular capillaries exhibit postcapillary venule-like transformation that enhances the influx of inflammatory cells into the kidney allograft.

[Simultaneous occurrence of persistent hematuria (thin basement membrane nephropathy) and light-chain proteinuria (benign monoclonal gammopathy) in a middle-aged male]

IgG lambda type of monoclonal gammopathy and thin basement membrane nephropathy were established in a middle-aged man examined because of persistent haematuria, lambda light-chain proteinuria and moderately diminished renal function. A 10% level of plasmocytosis was verified by bone-marrow aspiration. The more than 6-year follow-up showed the gammopathy to be benign. The thin basement membrane nephropathy was verified by electronmicroscopic analysis of renal tissue obtained by percutaneous renal biopsy: lamina densa of the glomerular capillaries thinned to 30-100 nm. In spite of the usually good outcome of thin basement membrane nephropathy, in this case it was accompanied by glomerular sclerosis, subsequent destruction of nephrons, hypertensive vascular alterations and a clinical deterioration of the renal function after 4 years. A rebiopsy excluded the possible complications (amyloidosis, non-amyloid immunoglobulin nephropathy, cylinder nephropathy, etc) of light-chain proteinuria.

[Successful treatment of acute tubulointerstitial nephritis associated with infectious mononucleosis and causing severe uremia]

A ten years old boy with severe acute renal failure was presented. The development of acute uremia was proceeded by infectious mononucleosis. Renal biopsy revealed acute tubulointerstitial nephritis. Peritoneal- and haemodialysis was completed by steroid therapy and cytostatic treatment when glomerular proteinuria was observed. Following a 2 months uremic period the patient cured completely.

The distal nephron is preferentially infiltrated by inflammatory cells in acute interstitial nephritis

In acute interstitial nephritis (AIN), mononuclear cells invade the tubules (tubulitis). The segmental localization of tubulitis is not precisely known. To clarify this question, formalin-fixed kidney biopsy specimens from 13 patients with AIN were studied stereologically by identifying cortical tubules with segment-specific markers. The periodic acid-Schiff reaction, peanut lectin, and antibodies against Tamm-Horsfall protein and epidermal cytokeratins all applied to the same section were used to identify the proximal tubules (PTs), distal convoluted tubules, distal straight tubules, and the cortical collecting system (connecting tubules and cortical collecting ducts), respectively. Morphometrically, an estimate of the relative volume of the inflammatory cell infiltrates within each category of tubular segments was obtained. Inflammatory cells were infrequently found in PTs (1.2%) but were frequently localized in distal tubules and the cortical collecting system (7.6%). There was no difference in the amount of the inflammatory cell infiltrate within these segments. Re-examination of an electron microscopic study of AIN carried out in this laboratory revealed that mononuclear cells were rarely seen in convoluted PTs but were frequently observed in straight PTs and all segments distal to them. The observations indicate that it is the distal nephron which is primarily affected by inflammatory cell infiltration in AIN.

Immunohistochemical identification of tubular segments in percutaneous renal biopsies

To identify the renal cortical tubular segments involved in tubulo-interstitial disease in formalin-fixed, paraffin-embedded percutaneous kidney biopsies, we developed multiple immunolabeling protocols using segment-specific tubular markers. The present study of biopsies from patients with minimal change or thin basement membrane nephropathy provides a baseline for interpretation of histopathology. Proximal tubules were stained either by the PAS reaction or by the biotinylated Phaseolus vulgaris erythroagglutinin (PHA-E)-streptavidin-gold-silver system (brush borders black). The anti-Tamm-Horsfall (THP) antibody-immunoperoxidase (aminoethylcarbazole, AEC-IPO), and anti-epidermal cytokeratins (ECK) antibodies-immunoalkaline-Fast Blue BB methods marked the distal straight tubules and the cortical collecting system red-brown and blue, respectively. When these immunolabelings were combined, the coapplication of AEC-PO-labeled peanut agglutinin (PNA) or anti-epithelial membrane antigen antibody-AEC-IPO technique (both are markers for distal nephron) visualized the apical membranes of distal convoluted tubules. In the protocol PHA-E + PNA + THP + ECK, the tubular basement membranes were outlined by the anti-laminin antibody-AEC-IPO staining, carried out simultaneously. The protocol PNA + THP + ECK + PAS was found to be quite appropriate multiple immunolabeling method for the tubules, and is recommended for use as a tool in the study of tubulo-interstitial diseases.

[Surgical treatment of stomach cancer with extended removal of lymph nodes]

The authors evaluate the results of extensive lymph node dissection for gastric cancer at 50 patients. It has been found that the lymph node dissection did not increase the risk of operation. The mortality rate was 2%. The average number of removed and histologically examined lymph nodes was 26. The extensive lymph node dissection and the accurate histology provided opportunity for precise staging. Their first evaluation of survival showed an encouraging improvement of prognosis regard to that of patients survival treated by traditional surgical method. Besides it they reviewed the classification of Japanese Research Society for Gastric Cancer for the lymph drainage of the stomach and the surgical technique of the lymph node dissection.

Double and triple immunocytochemical labelling at the light microscope level in histopathology

Double and triple immunocytochemical detection methods for routine use in histopathology were investigated. For double immunostaining, the combinations of immunogold-silver staining (IGSS, black) with an immunoperoxidase method (3-amino-9-ethylcarbazole, red-brown) or with an immunoalkaline phosphatase method (Fast Red TR, red) proved very useful. These were followed by a Haematoxylin counterstain. An alternative approach using immunoperoxidase (red-brown) and immunoalkaline phosphatase (Fast Blue, BB, blue) methods was also successful, particularly for frozen sections of unfixed tissue and for the establishment of intermediate filament coexpression in tumours. The coexistence of desmin with vimentin in rhabdomyosarcoma, and of glial fibrillary acidic protein with vimentin in ependymoma, could be demonstrated directly by means of non-crossreacting murine and rabbit antibodies in the above combinations. The black (IGSS), red-brown (immunoperoxidase) and blue (immunoalkaline phosphatase) colours gave excellent contrast in triple immunostaining. The side-by-side demonstration of helper and suppressor T lymphocytes during renal allograft rejection, of kappa and lambda light chains in B-immunoblastic lymphoma, and of T and B lymphocyte populations in non-Hodgkin's lymphomas provided immediate information on the topography and cellular organization of the tissues.

Frequency of light chain deposition nephropathy relative to renal amyloidosis and Bence Jones cast nephropathy in a necropsy study of patients with myeloma

The frequency of light chain deposition nephropathy relative to renal amyloidosis and Bence Jones cast nephropathy was determined in a necropsy study of 57 patients with myeloma. The diagnosis of light chain deposition nephropathy was established by immunofluorescence microscopic examination of kidney tissue demonstrating linear deposits of a single light chain isotype along tubular and other renal basement membranes, and by electron microscopy, which showed the characteristic granular nature of the deposits. In this study, 3 patients (5%) had kappa light chain deposition nephropathy, 6 (11%) had renal amyloidosis, and 18 (32%) had Bence Jones cast nephropathy. The data indicate that light chain deposition nephropathy is a rare complication of multiple myeloma.

[Light-chain nephropathy]

The authors deal with the clinicopathology of the renal, alterations in light-chain disease in connection with 6 cases. The disease was recognized by the monotype (in 5 cases kappa, in 1 case lambda) immunoreactivity of the light-chain paraprotein deposited in the basal membranes of the renal tissue. Electron microscopic examinations proved the fine-granulated, electrodense character of the paraprotein. Multiple myeloma was found in 3 cases and plasma cell dyscrasia of non-tumorous characteristic in 3 cases in the background of the deposition. The renal involvement appeared clinically in the picture of proteinuria without nephrosis syndrome and in progressing azotemia. Chronic renal insufficiency developed during some months in 5 patients. Morphologically renal impairment manifested in interstitial fibrosis, tubular atrophy and ateriolar hyalinosis was seen. These were associated with different glomerular alterations, for instance in 3 cases with nodular glomerulosclerosis. In 1 patient with plasma cell dyscrasia of non-tumorous characteristic nodular glomerulosclerosis and semilunar formation was observed in 56% of the glomeruli. In an other patient with myeloma the simultaneous existence of cylinder nephropathy and light-chain nephropathy was demonstrated. Both observations are unusual phenomena in plasma cell dyscrasia.

[Recurrence of focal sclerosing glomerulonephritis in the kidney graft]

This is the first report on the recurrence of a glomerular disease in renal transplant in Hungary. The primary disease of the girl died at the age of 13 was focal sclerosing glomerulonephritis with slight mesangial cell proliferation. The first symptoms appeared at the age of 6.5 and they progressed rapidly. Four years later, because of the severe nephrotic syndrome and chronic renal failure, renal transplantation was performed with the synchronous removal of the patient's own kidneys. In the latter an interesting immunohistological finding has been observed: beside the usual positivities, the basement membrane of the distal tubule at the opposite side of the macula densa showed a strong reaction with anti IgM and a somewhat weaker positivity with anti C3 sera. The primary disease recurred very soon. A mesangial cell proliferation, however did not develop, in contrary to the primary disease, which contradicts the theory that the mesangioproliferative form would be a distinct clinicopathological entity.

[Morphologic changes in tubulo-interstitial diseases of the kidney]

Morphological changes providing basis for the diagnosis of certain tubular-interstitial diseases of kidney are surveyed in this paper. Different cylinders in tubular lumen, changes of tubular epithelium of endocytotic and of other origin and inflammatory cell reactions of interstice should be considered light microscopically. Immune histological examination of tubular basal membrane is essential for proper diagnosis.

[Renal complications of multiple myeloma]

In connection with the analyses of 84 post-mortem examinations (47 men, 37 women, average age: 66.3 years) the author dealt with the renal complications of multiple myeloma. The signs of cylinder nephropathy, light-chain nephropathy, amyloidosis, nephrocalcinosis, urate nephropathy, acute renal insufficiency, renal vein thrombosis, acute and chronic pyelonephritis as well as the tumorous infiltration of the renal tissue have been sought for. The severity of the lesions were ranged into minimal, slight, moderate, and severe groups. On the basis of the semiquantitative morphological picture and the clinical data: 1. intact kidney (41 patients), 2. involvement of the kidney without azotemia (10 patients), 3. involvement of the kidney with azotemia (17 patients, serum creatinine level: greater than 177 mumol/l) and 4. renal involvement with chronic renal insufficiency associated with uremia (16 patients) were discerned. In the background of 33 cases (39%) with deteriorated renal function cylinder nephropathy was found most frequently (27 occasions) (32%). Every other complication occurred significantly less frequently e.g. amyloidosis or kappa-light-chain nephropathy occurred in 3 cases each.

[Immunohistochemical, immunocytochemical and electron microscope studies in experimental E. coli pyelonephritis]

Authors have studied in apostematous pyelonephritis induced by the ligation of the ureter and the intravenous injection of E coli bacteria the localization and elimination with time of the pathogen. The pathogen was demonstrated by light and electron microscopy, its parietel antigen was localized with the light microscopic peroxidase antiperoxidase and post-embedding electron microscopic immunogold techniques. Two days after inoculation the suppurative inflammation of tubulo-interstitial foci was observed; in the capillaries, interstitium, and tubuli, free and phagocyted bacteria were encountered. In the interstitium, in the proximal tubuli and in the capillary space of some glomeruli bacterial groups were observed. Intracapillary bacteria were attached by their outer wall to the surface of endothelial cells. In the tubuli this adherence occurred with pili or with the outer layer of bacterial wall. From the seventh day after inoculation macrophages containing PAS-positive globuli appeared in the interstitium. Under the electron microscope these globuli proved to be features composed of myelin figures of phagolysosomal origin. Globuli and the myelin figures possessed an E. coli antigenicity. Thirteen weeks after inoculation E. coli antigen positivity was found in the cytoplasm of inflammatory cells in the tubular walls and in the suppurative cylinders, The organism was apparently unable to eliminate the materials derived from the pathogenic microorganisms.

Acute human pyelonephritis: leukocytic infiltration of tubules and localization of bacteria

The fine structural details of how leukocytes appear in the lumen of tubules and the localization of bacteria in the tubulo-interstitial space were studied by light and electronmicroscopy in renal cortical biopsy specimens from three patients with acute pyelonephritis. The cells of interstitial infiltrates infiltrated and sometimes disrupted the cortical collecting tubules preferentially, while inflammatory infiltration of the proximal and distal convoluted tubules occurred more rarely. Since the emigration of tubular wall-localized individual leukocytes into the lumen was not observed even in long series of thin sections, focal inflammatory disruption of the uriniferous ducts was considered to be the morphological basis of the intratubular accumulation of leukocytes. The structural simplicity of the collecting tubular cells is suggested to be the reason for their preferential involvement in the drainage of the interstitial suppuration, although a role for specific carbohydrate receptors cannot be excluded. The bacteria were usually found within the neutrophilic granulocytes and macrophages of the interstitial infiltrates, and within and among the cells of leukocyte casts. Additionally, pure bacterial colonies were noticed in the lumen of a few collecting tubules. The problem of the adherence of the bacteria to the surface of the tubular cells is discussed.

Microvascular injury and repair in acute human bacterial pyelonephritis

Acute inflammatory cell-capillary endothelial cell interactions, related to injury and repair, were investigated light and electron microscopically in acute human bacterial pyelonephritis. In inflammatory infiltrate-adjacent microvessels, the small capillaries were completely occluded by leukocyte plugs and the large capillaries were densely filled with acute inflammatory cells adhering to the endothelium. Severe damage to small and large capillaries was observed around endothelium adherent, degranulated neutrophil granulocytes containing phagocytosed bacteria. There were spaces in the endothelium, degradation of the vascular basement membrane, of the perivascular interstitial matrix and of collagen fibrils, with fibrin deposition and vessel wall fragmentation. In the small capillaries relatively distant from the interstitial infiltrates, emigration of leukocytes was frequently seen. Around the escaping cells the endothelial lining displayed occasional discontinuities, allowing leakage of vascular fluid into the interstitial space. Some small capillaries not related to the infiltrate were occluded by fibrin thrombi with apparent damage to the endothelial cells and disruption of the capillary wall. Various reparative changes were noticed in association with this change including capillary neovascularization. The findings confirm the existence of polymorphonuclear leukocyte-mediated injury of capillaries during the development of inflammatory responses in acute pyelonephritis.

Immunofluorescent examination of the kidney post mortem

106 selected kidneys removed at autopsy were studied by direct immunofluorescence using polyvalent antisera against human immunoglobulins, light chains, complement fractions and fibrinogen. The immunofluorescence was a suitable method to solve differential diagnostic problems that arose at autopsy. The diagnostic value was the most obvious in cases of immunologically mediated renal diseases and in immunologically mediated systemic diseases involving the kidneys. Negative immunofluorescence findings were also useful to determine the pathogenesis of renal lesions, especially in vasculopathies. The immunofluorescence of postmortem material showed similar disturbances to that obtained with biopsy material. At various sites, especially in the tubulo-interstitium, additional electron microscopical study was sometimes needed to localise the immune deposits exactly. The fluorescent microscopical examination of frozen sections of kidney taken at necropsy turned out to be more adequate than the immunoperoxidase examination of formalin-fixed, paraffin-embedded sections.

Phagocytosis of bacteria by proximal tubular epithelium in experimental pyelonephritis

Acute pyelonephritis was induced in rats by temporary unilateral ureteric obstruction and the intravenous injection of Escherichia coli. Animals were sacrificed 48 h after infection and changes in renal cortical tubules due to the presence of bacteria were studied. Bacteria appeared and multiplied in the tubular lumina and proximal tubular epithelial cells endocytosed the microorganisms in large numbers. Coalescence of phagosomes with lysosomes resulted in the surrounding of engulfed bacteria with acid phosphatase. However, the lysosomal apparatus of the cells did not eliminate Escherichia coli since the bacteria multiplied within phagosomes and destroyed the normal cell architecture. The peritubular interstitial inflammatory infiltrate caused ischemia of tubules, enhancing bacterial damage to the proximal tubules. The cytoplasm of the injured tubular cells was sometimes detached from the basement membrane. Cells of the distal tubules and collecting ducts did not show significant endocytosis or bacterial tubular damage.

Arteriolar lesions in human renal biopsy material with special regard to the ultrastructural changes in the basal lamina network of the vascular wall

The arteriolar changes in renal biopsy samples were studied by light and electron microscopy and immunohistologic observations. Arteriolar hyaline thickening was found to occur in virtually all renal diseases, regardless of whether these were accompanied by hypertension or not. Only amyloidosis and dense deposit glomerulonephritis were accompanied by specific ultrastructural arteriolar changes. The nonspecific "hyalin" was shown ultrastructurally to contain various components: accumulated basement membrane material, fine granular deposit (with filamentous or lipid details), and granulovesicular and threadlike membrane structures. Presumably the material constituting these structures originates partly from the blood and partly from elements of the vascular wall itself.

Tubulointerstitial inflammation, cast formation, and renal parenchymal damage in experimental pyelonephritis

Some basic changes in experimental pyelonephritis were studied by transmission and scanning electron microscope. Initially, bacteria settled and multiplied in capillaries and venules. Leukocytes first marginated and then escaped from the capillaries, particularly to the wide peritubular interstitium. After opening the tubular basement membrane, the infiltrating leukocytes were immediately localized in the tubular wall between epithelial cells but were never seen between the epithelial cells and the underlying basement membrane. The inflammatory cells seemed not to be able to pass through the tight junctions of the nonnecrotic tubular epithelium. As a consequence of severe inflammatory injury, the tight junctions exhibited alterations of intermediate junction type. Where circumscribed necrosis of the tubular walls occurred, leukocytes appeared in the lumen. Thus, pus casts originated from these sites, apparently as drainage of interstitial abscesses. The secondary/regressive and regenerative/tubular changes were similar to those occurring after various tubular lesions.