In-situ end labelling with bromodeoxyuridine--an advanced technique for the visualization of apoptotic cells in histological specimens

DNA Fragmentation in Acute and Chronic Rejection After Renal Transplantation

Acute and chronic rejections are important denominators for the long-term function of renal grafts. One important indicator of cell damage is enzymatic DNA fragmentation. To investigate possible mechanisms, the rate of DNA fragmentation (TUNEL staining), the expression of tissue transglutaminase II (a marker of advanced DNA damage), and 8-hydroxy-2'-deoxyguanosine (8-OhdG), an indicator of oxidative injury of nucleic acids, were studied by immunohistochemistry. Semithin sections of renal biopsies revealed 23 patients to show acute interstitial rejections (Banff 97 IA, IB); eight patients, acute vascular rejection (Banff 97 IIA, IIB); and 20 patients, chronic allograft nephropathy (Banff 97 I to III). Correlations were calculated between apoptotic cells and serum creatinine at the time of biopsy and after 6 months. In acute rejection, the proximal tubular cells were apoptotic, particularly in regions with mononuclear infiltrates. In consecutive sections, these apoptotic tubular cells also showed damage by reactive oxygen species (positive 8-OhdG staining). Patients with acute interstitial rejection revealed the highest number of tubular DNA fragmentation (14.9 +/- 10.3) versus chronic allograft nephropathy (9.2 +/- 5.6) as TUNEL-positive cells per 80,000 micro m(2) (P < .05). Patients with acute vascular rejection showed a low degree of tubular apoptosis (6.8 +/- 5.1). There was no significant difference in glomerular DNA fragmentation between acute interstitial and chronic rejections: acute interstitial rejection = 7.1 +/- 5.9 versus chronic allograft nephropathy=6.1 +/- 3.9 TUNEL-positive cells per 80,000 micro m(2). There was a significant negative correlation between the degree of tubular (P < .01) and glomerular (P < .05) apoptosis and the serum creatinine at the time of biopsy as well as after 6 months in all patients irrespective of the Banff class. However, there was heterogeneity in the correlation between renal function and the degree of apoptosis in the glomerular and tubular compartments in the various Banff classes. A positive correlation (P < .01) was observed between the degree of tubular apoptosis and serum creatinine at 6 months after biopsy among patients with acute vascular rejection (Banff 97 IIA, IIB). The present data revealed a high degree of tubular DNA fragmentation associated with oxidative stress in acute interstitial rejection. Nevertheless, apoptosis did not generally negatively influence future renal function and may be important to clear proliferating cells. Apoptosis may also play a different pathophysiological role depending on the type of rejection.

Modern laser scanning microscopy in biology, biotechnology and medicine

Laser microscopic techniques currently used in morphology and cell biology represent highly sensitive tools for detecting biomolecules within their natural environment. Use of the fluorescence-, reflectance- and transmission modes of confocal laser scanning microscopes (CLSM) equipped with He-Ne- and Ar+-ion lasers for CeIV and DAB based detection of endogenous or immunobound enzymatic activities in tissue sections (vibratome, cryostat, paraffin and semithin plastic sections) opens a wide range of interesting new possibilities in cellular and molecular biology. Increased resolution power, blur-free confocal imaging, higher sensitivity, optical sectioning capability and 3D-image analysis provide a large quantity of valuable information about biological objects specimens. The new infrared multiphoton laser scanning microscopy (NIR-LSM) is increasingly becoming the optical tool of choice for (a) fluorescence imaging of cellular and subcellular components with high spatial and temporal resolution, (b) fluorescence resonance energy transfer between physiologically relevant molecular species involving protein-protein interactions, (c) nanoprocessing within living cells and tissues, with varied applications in (d) photochemistry and (e) medical diagnostics as well. Both, CLSM and NIR-LSM as modern microscopical strategies are indispensable in basic research and will prove to be invaluable for clinical diagnostic studies and therapy in the near future.

Damaged myocytes as detected by the colocalization of DNA fragmentation and tissue transglutaminase and their prognostic significance in enterovirus-associated dilated cardiomyopathy

BACKGROUND

Apoptotic cardiac myocytes have been described in chronic heart failure, but no data exist on the relationship between these 'damaged' myocytes and myocardial detection of enterovirus RNA often associated with dilated cardiomyopathy (DCM).

DESIGN

In patients with idiopathic DCM, endomyocardial biopsy samples were studied for enteroviral RNA by one step reverse transcription-polymerase chain reaction (PCR) and a subsequent hybridization of the PCR product using a Southern blot technique. The endomyocardial biopsies were further investigated for markers of cell damage and apoptosis: DNA fragmentation and expression of tissue-transglutaminase (TTG) in the myocytes using the in-situ endlabelling method or an anti-TTG-staining, respectively. To assess the prognostic significance of these two markers the correlation between the percentage of myocytes positive both for DNA fragmentation and TTG (the index of damaged myocytes) and the hemodynamic course of the patients during a mean follow-up period of 15.9 +/- 6.2 months was investigated prospectively by echocardiography.

RESULTS

In 14 (45%) of the 31 patients with idiopathic DCM, enteroviral RNA was found in the endomyocardial biopsy samples, while 17 patients (55%) were enterovirus-negative. In enterovirus-positive patients, the index of 'damaged' myocytes was significantly lower (10.7 +/- 4.9% vs. 19.2 +/- 8.8%, P = 0.002) and the left ventricular ejection fraction (LVEF) improved significantly (P = 0.00017 vs. P = 0.13) during long-term follow-up. In addition, a weak negative correlation was seen between the index of damaged myocytes and the changes in LVEF in all patients during long-term follow-up (r = - 0.48, P = 0.004).

CONCLUSION

Our results favour the view that enterovirus-positive patients with DCM have less damaged myocytes and a better haemodynamic course than enterovirus-negative patients.

Advances in cytochemical methods for detection of apoptosis

In an earlier article from this laboratory, the current methods developed to detect apoptosis in cells and tissues were highlighted, along with the challenges in their interpretation. Recent discoveries concerning the underlying biochemical mechanisms of apoptotic effector pathways have made possible further assays that allow a more direct measure of the activation of the apoptotic machinery in cells. This article summarizes some of these newer methods and extends the interpretation of the more classical assays of apoptosis in a defined cell system. We present data in KB and PC3 cell model culture systems induced to undergo apoptosis by the plant toxin ricin. Using a modified in situ nick translation assay (ISNT) with either Bodipy or BUdR labeling, we confirm that most cells showing altered nuclear morphology do not show reactivity with this assay until very late in the apoptotic process. We also show that only a minority of cells label with fluorescent annexin V during apoptosis but that apoptotic cells continue to internalize material from the cell surface through endocytosis after becoming reactive with annexin V. In addition, we describe the utility of a prototype of new assays for caspase substrate cleavage products, the detection of cleaved cytokeratin 18. It is these newer cleavage product assays that perhaps hold the greatest promise for specific detection of apoptosis in cells either in cell culture or in intact tissues. (J Histochem Cytochem 49:821-832, 2001)