Review on estimation of postmortem interval using FTIR spectroscopy / 法医学杂志

Estimation of the postmortem interval (PMI) is a practical task in daily forensic casework. Researches on PMI is an important practical project in forensic field. Estimation of the time since death is influenced by internal and external, antemortem and postmortem factors, thus the old methods have limitations. Fourier transform infrared (FTIR) spectroscopy has been applied to study the pure protein, nucleic acid and carbohydrate and to detect the changes in complex cells and tissues. At present because the powerful software has could be used to achieve the spectrum transformation, smoothing, baseline correction and normalization, it is possible to analyze the samples quantitatively with the FTIR which has been applied in the biology and clinical medicine. This paper has reviewed the mechanism of FTIR and its application in biomedicine. The postmortem FTIR spectral changes were also discussed, which showed its potential for estimating PMI.

Protection against cephalosporin-induced lipid peroxidation and nephrotoxicity by (+)-cyanidanol-3 and vitamin E

The ability of the clinically used cephalosporins: cephalothin, cefotaxime and cefotiam to induce lipid peroxidation (LPO) and renal damage was compared to that of nephrotoxic cephaloridine under in vivo conditions. Glutathione was measured in rat liver or in renal cortex as non-protein sulfhydryls. LPO was measured in plasma, renal cortex and liver by the generation of malondialdehyde or as the increase in renal cortical concentration of conjugated dienes. Impairment of renal function was measured as the decrease in renal cortical accumulation of the organic anion p-aminohippurate (PAH). Administration of cephalosporins to rats as a single dose (2000 mg/kg, ip) induced a significant glutathione-depletion in the renal cortex with cephaloridine, and in the liver with cephaloridine, cephalothin and cefotiam. Treatment of rats with cephaloridine, cephalothin and cefotiam (200, 500, or 1000 mg kg-1 day-1, ip) for 5 days resulted in a dose-dependent increase of LPO in the renal cortex. While cephaloridine induced the highest concentration of conjugated diene, cefotaxime had no effect. Measurements of PAH accumulation in renal cortical slices from cephalosporin-treated rats showed a dose-dependent decrease in the renal cortical accumulation of PAH. Pretreatment with the antioxidants vitamin E or cyanidanol (400 mg kg-1 day-1, ip) 1 h before treatment with cephaloridine, cephalothin or cefotiam (1000 mg kg-1 day-1, ip) for 3 days inhibited cephalosporin-induced LPO and significantly reduced the impairment of renal cortical accumulation of PAH. The potential of different cephalosporins for inducing LPO and reducing PAH accumulation was ranked as follows: cephaloridine > cephalothin > cefotiam > cefotaxime.

Life-long food restriction prevents renal membrane lipid deposition and lowers renal work in rats.

Renal cortical brush-border (BBM), basolateral membrane (BLM), and medullary plasma membrane (mPM) preparations were analyzed to assess the effects of life-long food restriction in aged rats on membrane lipid content. Young male Fischer 344 x Brown-Norway F1 rats consumed food ad libitum (young AL) or were food-restricted (FR, 60% of AL consumption) for either 6 weeks (young FR) or until the age of 30 months old (old FR). Senescent FR rats had 50 per cent decreases in fractional excretion of Na and K (p < 0.001) as compared with the young AL rats. Long-term FR reduced phosphate and titratable acid excretion by 80 per cent (p < 0.001). These values were not significantly different from those observed in young rats during 6 weeks of FR. Food restriction decreased renal Na, K-ATPase activity by 50 per cent (p < 0.001) in both old and young FR animals. Reduction of food intake, in old and young rats, decreased all BBM phospholipid concentrations (phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin) by 50 per cent than in the AL rats (p < 0.001). In BLM, chronic FR resulted only in lower phosphatidylcholine concentration (by 21%, p < 0.05) while phosphatidylethanolamine was increased approximately 80 per cent (p < 0.001). Total phospholipid content in mPM was progressively decreased by 23 per cent (p < 0.05) in the young FR group to be 55 per cent (p < 0.001) in the old FR rats. Cholesterol content was reduced in BBM and mPM by 38 per cent and 25 per cent (p < 0.05), respectively, during long-term FR. Both total phospholipid and cholesterol contents detected in mPM of the old FR rats were significantly lower than those obtained from the young FR animals (by 42%, p < 0.001 and 12%, p < 0.05, respectively). Plasma glucose, blood urea nitrogen, and body weight maintained at significantly lower levels during chronic FR. That life-long FR could prevent renal membrane lipid deposition and could lower renal work may explain the mechanisms that FR can delay the onset and diminish the severity of age-associated renal diseases.

Standardization of a fluorimetric assay for the determination of tissue angiotensin-converting enzyme activity in rats

The tripeptide Hip-His-Leu was used to standardize a fluorimetric method to measure tissue angiotensin-converting enzyme (ACE) activity in rats. The fluorescence of the o-phthaldialdehyde-His-Leu adduct was compared in the presence and absence of the homogenate (25 µl) to determine whether the homogenate from different tissues interfered with the fluorimetric determination of the His-Leu product. Only homogenates from lung and renal medulla and cortex showed significantly altered fluorescence intensity. To overcome this problem, the homogenate from these tissues were diluted 10 times with assay buffer. The specificity of the assay was demonstrated by the inhibition of ACE activity with 3 µM enalaprilat (MK-422). There was a linear relationship between product formation and incubation time for up to 90 min for homogenates of renal cortex and medulla and liver, for up to 60 min for ventricles and adrenals and for up to 30 min for the aorta, lung and atrium homogenates. In addition, there was a linear relationship between product formation and the amount of protein in the homogenates within the following range: lung, 30-600 µg; renal cortex and medulla, 40-400 µg; atrium and ventricles, 20-200 µg; adrenal, 20-100 µg; aorta, 5-100 µg; liver, 5-25 µg. No peptidase activity against the His-Leu product (31 nmol), assayed in borate buffer (BB), was detected in the different homogenates except the liver homogenate, which was inhibited by 0.1 mM r-chloromercuribenzoic acid. ACE activity in BB was higher than in phosphate buffer (PB) due, at least in part, to a greater hydrolysis of the His-Leu product in PB. ACE activity of lung increased 20 percent when BB plus Triton was used. Enzyme activity was stable when the homogenates were stored at -20o or -70oC for at least 30 days. These results indicate a condition whereby ACE activity can be easily and efficiently assayed in rat tissue samples homogenized in BB using a fluorimetric method with Hip-His-Leu as a substrate.

Individual or combined effects of enalapril and verapamil on chronic cyclosporine nephrotoxicity in rats

Previous studies have demonstrated that enalapril and verapamil seem to attenuate the cyclosporine nephrotoxicity. However, the mechanisms have not been completely understood, especially on molecular events. The aim of this study was to examine the effect of individual or combined treatment on osteopontin, TGF-beta, endothelin-1 and procollagen alpha 1(I) mRNA expressions. Enalapril (50 mg/L in drinking water) and verapamil (0.5 mg/kg/day, subcutaneously), alone or in combination, were administered to rats with chronic cyclosporine nephrotoxicity (cyclosporine, 25 mg/kg/day, subcutaneously) (n = 5 each). Five rats treated with olive oil vehicle were used as control. After 4 weeks, biochemical parameters were measured, and renal cortical mRNA levels were evaluated by Northern blot analysis. Cyclosporine reduced renal creatinine clearance significantly and induced renal cortical osteopontin, TGF-beta, endothelin-1 and procollagen alpha 1(I) gene expressions around 13.5 +/- 1.3, 2.4 +/- 0.2, 1.5 +/- 0.1, 1.9 +/- 0.1 folds, respectively. Individual treatment with enalapril or verapamil significantly suppressed the osteopontin and TGF-beta mRNA expression, but not endothelin-1 and procollagen alpha 1(I). Combined treatment also inhibited the osteopontin and TGF-beta mRNA expression but there was no difference between combined and individual treatment. In conclusion, enalapril or verapamil significantly blunted the cyclosporine-induced osteopontin and TGF-beta gene expressions. However, combined treatment did not show any additive effect.

Receptores adrenérgicos y transporte activo de iones en rebanadas de corteza renal de cobayo / Adrenergic receptors and active ion transport in guinea pig kidney cortex slices

Se estudió el efecto de agonistas alfa y beta sobre los mecanismos de transporte de electrolitos a nivel de las células de túbulo proximal en rebanadas de corteza renal de cobayo, a saber: el mecanismo que intercambia Na+ por K+ y el mecanismo que expulsa Na+ acompañado de Cl- y agua. Los resultados fueron los siguientes: 1) Todas las drogas simpaticomiméticas, indistintamente de su potencia relativa para estimular un tipo de receptor, estimularon la expulsión de Cl- y agua, mientras que inhibieron parcialmente la ganancia de K+. 2) Los effectos anteriormente descritos, fueron mimetizados por un aumento en el gradiente de Ca2+ externo y por la teofilina, la cual actuó en ausencia de Ca2+ externo. 3) En ausencia de Ca2+ externo, la norepinefrina (agonista alfa) fue incapaz de producir efecto alguno; por el contrario, el isoproterenol (agonista beta) no necesitó Ca2+ externo para producir su efecto. 4) Con los resultados presentados, se puede sugerir que los agonistas alfa pudieran afectar los movimientos activos de iones en este tejido a través de Ca2+ extracelular mientras que los agonistas beta lo harían mediante la liberación de Ca2+ endógeno