A novel method for the evaluation of proximal tubule epithelial cellular necrosis in the intact rat kidney using ethidium homodimer

BACKGROUND: Ethidium homodimer is a cell-membrane impermeant nuclear fluorochrome that has been widely used to identify necrotic cells in culture. Here, we describe a novel technique for evaluating necrosis of epithelial cells in the proximal tubule that involves perfusing ethidium homodimer through the intact rat kidney. As a positive control for inducing necrosis, rats were treated with 3.5, 1.75, 0.87 and 0.43 mg/kg mercuric chloride (Hg(2+), intraperitoneal), treatments which have previously been shown to rapidly cause dose-dependent necrosis of the proximal tubule. Twenty-four h after the administration of Hg(2+), ethidium homodimer (5 μM) was perfused through the intact left kidney while the animal was anesthetized. The kidney was then removed, placed in embedding medium, frozen and cryosectioned at a thickness of 5 μm. Sections were permeabilized with -20°C methanol and then stained with 4',6-diamidino-2-phenylindole (DAPI) to label total nuclei. Total cell number was determined from the DAPI staining in random microscopic fields and the number of necrotic cells in the same field was determined by ethidium homodimer labeling. RESULTS: The Hg(2+)-treated animals showed a dose-dependent increase in the number of ethidium labeled cells in the proximal tubule, but not in other segments of the nephron. Other results showed that a nephrotoxic dose of gentamicin also caused a significant increase in the number of ethidium labeled cells in the proximal tubule. CONCLUSION: These results indicate that this simple and sensitive perfusion technique can be used to evaluate cellular necrosis in the proximal tubule with the three-dimensional cyto-architecture intact

Air-flow geometry in air sparging of fine-grained sands

Laboratory visualization experiments in fine- to very fine-grained sands (grain diameter <0.21 mm) reveal a previously unrecognized air-flow geometry. This air-flow geometry is termed "chamber flow" and is characterized by: (1) a significant horizontal component, (2) pervasive air-flow coverage within a region demarcated by a distinct, irregular boundary, and (3) the presence of predominantly vertical inlet and outlet channels. The attributes of chamber flow differ significantly from channelized flow and pervasive/bubbly flow, which occur at larger grain sizes and have been described in the literature by several researchers. Previous research, which indicates a dramatic increase in contaminant removal time in sediments <0.2 mm, indirectly corroborates the phenomena observed in this study. The extent of sediment column affected by chamber flow of sparge air ranges from 4–54% on an area basis, and is approximately 28% on a volume basis. These values indicate that chamber air flow has the potential to affect a much larger percentage of the sediment column than either channelized or pervasive/bubbly flow. Because of the irregularity of air-flow chambers, in terms of both form and frequency, a detailed knowledge of stratigraphy is important to maximize air-sparging efficiency at sites where chamber flow is likely to occur. Des expériences de visualisation en laboratoire dans des sables à grains fins à très fins (diamètre des grains inférieur à 0,21 mm) ont mis en évidence une géométrie des écoulements d'air non reconnue auparavant. Cette géométrie des écoulements d'air est nommée «écoulement en cavité» et est caractérisée par (1) une composante horizontale significative, (2) un domaine d'expansion de l'écoulement d'air dans une région délimitée par une frontière distincte et irrégulière, et (3) la présence de chenaux essentiellement verticaux d'entrée et de sortie. Les caractères de l'écoulement en cavité diffèrent significativement de l'écoulement en chenaux et de l'écoulement expansif en bulle, qui se produisent pour des tailles de grains plus grandes et qui ont été décrits dans la littérature par plusieurs chercheurs. Une étude antérieure, qui indique un accroissement considérable du temps de déplacement d'un polluant dans des sédiments de granulométrie inférieure à 0,2 mm, confirme indirectement les phénomènes observés dans ce travail. La part de la colonne de sédiment affectée par l'écoulement en cavité de l'air poussé et injecté va de 4 à 54% par rapport à la surface, et est d'environ 28% en volume. Ces valeurs indiquent que l'écoulement d'air en cavité a la capacité d'affecter une part de la colonne de sédiment bien plus vaste que l'écoulement en chenaux ou en bulles expansives. À cause de l'irrégularité des cavités d'écoulement d'air, à la fois en termes de forme et de fréquence, une connaissance détaillée de la stratigraphie est importante afin que l'injection de l'air soit maximale à des sites où il est probable que l'écoulement en cavité se produise. La visualización de experimentos de laboratorio con arenas de tamaño de grano fino a muy fino (diámetro de grano inferior a 0,21 mm) revela la existencia de una geometría de flujo de aire que no se había identificado previamente. Esta geometría es denominada "flujo en cámara" y se caracteriza por: (1) una componente horizontal significativa, (2) la cobertura generalizada del flujo de aire dentro de una región delimitada por un contorno distinto e irregular, y (3) la presencia de canales predominantemente verticales en las zonas de entrada y salida. Los atributos del flujo en cámara difieren significativamente del flujo en canales y el flujo generalizado/de burbujas, los cuales tienen lugar con tamaños mayores de grano y han sido descritos en la literatura por diversos investigadores. Las investigaciones previas, que indican un aumento enorme en el tiempo de descontaminación necesario para sedimentos de tamaño inferior a 0,2 mm, corroboran de forma indirecta los fenómenos observados en este estudio. La zona afectada por flujo en cámara durante la inyección de aire en la columna de sedimentos varía entre el 4 y el 54% en área, lo cual equivale aproximadamente al 28% en volumen. Estos valores indican que el flujo en cámara de aire tiene el potencial de afectar a un porcentaje de la columna mucho mayor que los otros mecanismos de flujo. Debido a la irregularidad de las cámaras de flujo de aire, tanto en forma como en frecuencia, es importante adquirir un conocimiento detallado de la estratigrafía para maximizar la eficacia de la inyección de aire en lugares en los que es probable el desarrollo de flujo en cámara.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42337/1/10040-9-2-168_s100400000104.pd

Metabolic and hormonal studies of Type 1 (insulin-dependent) diabetic patients after successful pancreas and kidney transplantation

Long-term normalization of glucose metabolism is necessary to prevent or ameliorate diabetic complications. Although pancreatic grafting is able to restore normal blood glucose and glycated haemoglobin, the degree of normalization of the deranged diabetic metabolism after pancreas transplantation is still questionable. Consequently glucose, insulin, C-peptide, glucagon, and pancreatic polypeptide responses to oral glucose and i.v. arginine were measured in 36 Type 1 (insulin-dependent) diabetic recipients of pancreas and kidney allografts and compared to ten healthy control subjects. Despite normal HbA1 (7.2±0.2%; normal <8%) glucose disposal was normal only in 44% and impaired in 56% of the graft recipients. Normalization of glucose tolerance was achieved at the expense of hyperinsulinaemia in 52% of the subjects. C-peptide and glucagon were normal, while pancreatic polypeptide was significantly higher in the graft recipients. Intravenous glucose tolerance (n=21) was normal in 67% and borderline in 23%. Biphasic insulin release was seen in patients with normal glucose tolerance. Glucose tolerance did not deteriorate up to 7 years post-transplant. In addition, stress hormone release (cortisol, growth hormone, prolactin, glucagon, catecholamines) to insulin-induced hypoglycaemia was examined in 20 graft recipients and compared to eight healthy subjects. Reduced blood glucose decline indicates insulin resistance, but glucose recovery was normal, despite markedly reduced catecholamine and glucagon release. These data demonstrate the effectiveness of pancreatic grafting in normalizing glucose metabolism, although hyperinsulinaemia and deranged counterregulatory hormone response are observed frequently

Psychological and physiological predictors of lipids in black males

The association between lipids and both psychological and physiological measures were examined in this study of healthy black males. The results revealed that certain psychological measures, namely, State and Trait Curiosity and Trait Anger, explained a significant proportion of the variance in high-density lipoproteins (HDL), low-density lipoproteins (LDL), and triglycerides. Although psychological factors accounted for a significant proportion of the variance in lipids (29% for HDL, 25% for LDL, 64% for LDL/HDL, 29% for triglyceride), the amount of explained variance was significantly increased by the inclusion of both psychological and physiological variables in the regression equation. However, neither of the psychological variables explained any of the variance for total cholesterol when physiological variables were included in the regression analysis. The overall pattern of the findings suggests that black males who are at increased risk for elevated lipid levels may be identified by their level of mental vigilance, the frequency at which their anger is experienced, and the presence of other traditional risk factors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44812/1/10865_2004_Article_BF00845357.pd