Mechanism of elevation of serum alkaline phosphatase activity in biliary obstruction: an experimental study

Oral Toxicity and Hypotensive Influence of Sericin-Derived Oligopeptides (SDOs) from Yellow Silk Cocoons of Bombyx mori in Rodent Studies

Sericin-derived oligopeptides (SDOs) from yellow silk cocoons exhibit antihypertensive and hypoglycemic properties in both in vitro and in vivo studies. This study investigated the acute toxicity of SDOs as a novel food for human consumption using female ICR mice and Wistar rats, as well as the chronic toxicity test on both sexes of Wistar rats. Clinical chemistry, hematology, and histopathological studies revealed that SDOs were safe for a single dose of 2000 mg kg-1 body weight (BW) and daily oral administration of 50, 100, and 200 mg kg-1 BW for six months. The chronic toxicity study additionally measured the rats' systolic blood pressure (SBP) and blood sugar monthly as they slowly aged. In the 2nd month for male rats and the 4th month for both sexes, SDOs had a significant hypotensive effect on Wistar rats' blood pressure, lowering it from 130 mmHg to a plateau at 110-115 mmHg. In contrast, the blood pressure of the control rats exceeded 140 mmHg after five months. Nonetheless, the hypoglycemic effect was not observed. Measurements of SBP and blood glucose in aged rats during chronic toxicity tests yielded insights beyond ordinary toxicity, including the health and fitness of the lab rats, perhaps resulting in novel discoveries or areas of study that justify the sacrifice of the animals' lives.

Morinda lucida stem bark reversed the pattern and extent of lead nitrate-induced liver injury in Wistar rats

Lead toxicity remains one of the most important occupational and environmental health problems with characteristic features that are incompatible with life. Considering the foregoing, we investigated the ameliorative potentials of Morinda lucida stem bark (MLSB) extract on lead nitrate-induced hepatic injury with particular emphasis on its effects on the pattern and extent of lead nitrate toxicity. Thirty-six adult Wistar rats were randomly assigned into six groups (n=6). Normal control group received 2.2mL/kg distilled water only for 4 weeks while hepatic injury was induced by 2-week oral administration of 30mg/kg lead nitrate to experimental rats in the remaining five groups. Following induction, test groups were treated with MLSB for another 2 weeks at 100, 250, and 500mg/kg concentrations respectively while silymarin was administered orally for 2 weeks to positive control group. At the end of the study, serum activities of liver function enzymes and tissue levels of malondialdehyde were determined. Patterns and extent of injury were determined in hematoxylin and eosin-stained section. The result revealed a significant reduction in sera levels of liver function enzymes and tissue level of malondialdehyde (MDA) in extract treated groups. Lead nitrate-induced necrotic changes and other deranged features observed in histological sections were multifocal and they span through multiple zones of hepatic acini (panacinar), MLSB at 250mg/kg concentration reversed by some of these effects. The study concluded that ameliorative property of MLSB could be due to the antioxidant and membrane stabilizing properties of its phenolic compounds.

Dynamic serum alkaline phosphatase is an indicator of overall survival in pancreatic cancer

Background

The prognostic role of serum alkaline phosphatase (ALP) has been found in several kinds of solid malignant tumor, but has never been extensively discussed in pancreatic cancer, especially through the application of dynamic survival model which incorporates the varying nature of ALP measurements.

Methods

We conducted a retrospective study which successfully collected 551 histopathologically confirmed pancreatic ductal adenocarcinoma (PDAC) patients from a cancer specialized hospital in southwest China. The association between variant ALP which measured during the whole survival period and the overall survival (OS) of PDAC patients was evaluated by using dynamic Anderson-Gill (AG) model. Exhaustive sensitivity analysis was performed by adopting continuous cut-offs of ALP.

Results

After adjusted for possible confounding of serum albumin, total bilirubin and leukocyte counts, AG model revealed that, serum ALP during the survival period was nonlinearly associated with the OS of PDAC: for resected patients, compared with those whose ALP results ranged within the first quartile (<P₂₅), patients whose ALP measurements belonged to the second (P₂₅-P₅₀), the third (P₅₀-P₇₅), and the forth (>P₇₅) quartiles were observed 1.14 (95% CI: 0.29–4.56), 3.93 (95% CI: 1.23–12.60), 3.87 (95% CI: 1.32–11.36) folds of death hazard; whereas in un-resected PDAC patients, the hazard ratios (HRs) were 1.15 (95% CI: 0.79–1.68), 1.92 (95% CI: 1.32–2.78), and 1.97 (95% CI: 1.30–2.98), respectively. Sensitivity analysis revealed that, for both resected and un-resected patients, the results of AG model were robust with regard to various cut-offs of ALP, and an increased ALP was in general associated with significantly increased hazard of death.

Conclusion

Serum ALP during the survival period was significantly associated with the OS of PDAC patients, especially for resected early stage PDAC patients. Future studies with expanded sample size and refined prospective design should be implemented to corroborate our major findings. Besides, the underlying mechanism for this possible hazardous role of ALP should also be investigated.

Clinical Pathology Approaches to Hepatic Injury

Testing the blood for evidence of hepatic damage and dysfunction frequently involves measuring several blood constituents simultaneously to screen for disease. While useful, this approach occasionally leads to apparent disparities between the blood test results, and the results of other diagnostic tests such as histology. In part, these perceived discrepancies may stem from a lack of appreciation for tissue, cellular, and molecular factors that affect the appearance of hepatic disease biomarkers in the blood. Further confusing the matter is that in some instances the mechanisms responsible for the appearance of diagnostic compounds in blood are only partially understood. Many of the known factors that affect hepatic biomarkers are similar to those affecting other tissue markers, while others are unique to the liver, such as those involved with cholestasis. Disease conditions can also cause misleading results by affecting tissue concentrations of test compounds, hepatic mass, and the clearance rate of compounds from the blood. Knowledge of the factors affecting the blood concentrations of biomarkers, as well as investigations into the mechanisms behind changes to hepatic biomarker concentrations, may allow for a better interpretation of blood test results and fewer inconsistencies between diagnostic results.

Comparison of rat and human alkaline phosphatase isoenzymes and isoforms using HPLC and electrophoresis

Total activity of alkaline phosphatase (ALP) in serum represents the sum of activities of some isoenzymes and their numerous isoforms derived from various tissues of the organism. The aim of this work was to separate ALP isoenzymes and their isoforms in rat and human serum, compare the properties of serum ALP isoforms in rats and humans, and determine the usefulness of some analytical methods for specific measurements of ALP isoenzyme and isoform activities. Two methods of separation, i.e. high-performance liquid chromatography (HPLC) and agarose gel electrophoresis were chosen. The combination of HPLC with electrophoresis of the eluted fractions and with ALP inhibition methods (urea, l-phenylalanine), inactivation (heat) and precipitation (wheat-germ lectins) enabled the identification of isoenzymes and isoforms of ALP in serum. Using chromatography and a post-column reactor, three isoforms of the intestinal isoenzyme and one bone isoform of a tissue non-specific isoenzyme were detected. Rat serum differs significantly from human as regards activities of intestinal and hepatic isoforms, whereas the properties of the bone isoform are similar in both species. Our HPLC method offers a higher resolution than agarose gel electrophoresis with respect to ALP subfractions in rat serum.

Redistribution and fate of colchicine-induced alkaline phosphatase in rat hepatocytes: possible formation of autophagosomes whose membrane is derived from excess plasma membrane

The redistribution and fate of colchicine-induced alkaline phosphatase (ALPase) in rat hepatocytes were investigated by electron microscopic enzyme cytochemistry and biochemistry. ALPase activity markedly increased in rat hepatocytes after colchicine treatment (2.0 mg/kg body weight, intraperitoneal injection). At 20-24 h after colchicine treatment, the liver showed the highest activity of ALPase. Thereafter, ALPase activity decreased and returned to normal levels at 48 h. In normal hepatocytes from control rats, ALPase activity was seen only on the bile canalicular membrane. However, at 20-24 h after colchicine treatment, colchicine-induced ALPase was redistributed in the sinusoidal and lateral (basolateral) membranes as well as in the bile canalicular membrane. At 30-36 h after colchicine treatment, ALPase activity on the basolateral membrane gradually decreased. In contrast, ALPase in the bile canalicular membrane increased along with the enlargement of bile canaliculi, suggesting that ALPase in the basolateral membrane had been transported to the bile canalicular membrane. Furthermore, ALPase-positive vesicles, cisternae and autophagosome-like structures were frequently seen in the cytoplasm. ALPase was also positive in some lysosomal membranes. ALPase in hepatocytes at 48 h after colchicine treatment returned to almost the same location as in control hepatocytes. Altogether, it is suggested that excessively induced ALPase is at least partially retrieved by invagination of the bile canalicular membrane and then transported to lysosomes for degradation. In addition, this study indicates that excess plasma membrane might be a possible origin of autophagosomal membrane.

Role of lipid peroxidation in biliary obstruction in the rat

There is poor evidence about the participation of lipoperoxidative processes in liver damage induced by biliary obstruction, thus the aim of this work was to study the role of lipid peroxidation in this model of liver injury. Biliary obstruction was induced in male Wistar rats by ligation of the common bile duct; control animals were sham operated. Rats were sacrificed at different times after surgery. Liver sections were used for glycogen and lipoperoxidation quantification. Markers of liver damage were determined in serum. All serum markers of liver damage increased after 1 day of biliary obstruction. Liver glycogen content decreased 1 day after surgery. On the other hand, lipoperoxidation increased later than markers of liver damage, suggesting that it is a consequence rather than the cause of liver injury. Moreover, administration of colchiceine (a good free-radical scavenger) or vitamin E prevented lipoperoxidation but not liver damage, confirming that lipoperoxidation does not play an important role in liver damage induced by biliary obstruction. This model of liver injury seems to be useful for testing hepatoprotective drugs that do not act as free-radical scavengers.

Altered zonal expression of the CD26 antigen (dipeptidyl peptidase IV) in human cirrhotic liver

Dipeptidyl peptidase IV is a cell surface ectopeptidase with widespread tissue distribution. Recently it was shown to display extracellular matrix-binding properties; therefore its role in cirrhosis is of interest. The aim of this study was to use monoclonal antibodies directed against the human CD26 antigen (which has been shown to be dipeptidyl peptidase IV) to study the distribution of this molecule in normal human and cirrhotic liver. Identical staining was obtained with the three monoclonal antibodies (TaI, 1F7 and TS145) and enzyme histochemistry. In normal liver (n = 11) intense staining of hepatic acinar zones 2 and 3 was present, but little staining was seen in zone I. Hepatocyte staining was confined to the bile canalicular domain. In cirrhotic livers (n = 23) obtained at transplantation, staining of regenerating nodules without a zonal pattern was present. In addition, we saw staining of the lymphoid cell infiltrate and proliferating bile ductules. In a minority of cirrhotic biopsy specimens (four) staining of the basolateral hepatocyte domain in regenerating nodules was seen. Biopsy specimens from hepatic allografts (n = 28) were used as disease controls. These samples all showed preferential staining of zones 2 and 3, similar to that in normal biopsy specimens. Eleven of these samples showed staining of the basolateral and bile canalicular domains. In conclusion, the normal acinar distribution of dipeptidyl peptidase IV (zones 2 and 3) is lost in cirrhotic nodules. Furthermore, the altered membrane distribution of this molecule in cirrhosis and allograft rejection may allow increased hepatocyte extracellular matrix interactions during organ remodeling.

Intrahepatic cholestasis: a review of biochemical-pathological mechanisms

Intrahepatic cholestasis involves impaired excretion of bile via the hepatobiliary system as a consequence of one or more lesions within the liver. In humans, intrahepatic cholestasis most often results as a side-effect of drug therapy and the clinical manifestation of this condition, jaundice, has been estimated to account for hospitalization in 2 to 5% of the cases for the general population and approaches as much as 20% in the elderly. With the aging of the population and the common occurrence of poly-drug therapy in geriatric patients, it is to be expected that jaundice due to drug-induced intrahepatic cholestasis will become even more prevalent, and accordingly the need to understand the basic mechanisms of this disease condition will become more urgent. The list of culprit agents implicated in the induction of intrahepatic cholestasis in humans is continually expanding. These include various steroid hormones, bile acids, drugs and other chemicals. Experimentally, a wide spectrum of agents has been shown to precipitate intrahepatic cholestasis. Over the years, a number of hypotheses on the biochemical and pathological mechanisms of intrahepatic cholestasis has emerged, including the following: impaired sinusoidal membrane function; interference with the distribution and binding of cytoplasmic endogenous carrier proteins; interference with mitochondrial energy supply; defects in the canalicular membrane including altered Na+/K+ -ATP-ase activity; impairment of microfilament and microtubule functions; interference with bile secretion involving bile acid dependent and independent fractions, and altered bile acid metabolism due to "hypoactive hypertrophic smooth endoplasmic reticulum". In partial agreement with the latter hypothesis, our studies indicated that impairment of the endoplasmic reticulum might represent one of the early stages in the development of intrahepatic cholestasis. Various experimental conditions that induce intrahepatic cholestasis to different degrees resulted in an interference of the synthesis of microsomal phospholipids and altered microsomal function. The conditions included the administration of various hepatotoxic compounds or steroids, pregnancy, delayed development of the endoplasmic reticulum in neonates, and dietary methyl donor or choline deficiency. This review reports the biochemical-pathological mechanisms postulated to be involved in the genesis of intrahepatic cholestasis with specific reference to experimental models of drug-induced intrahepatic cholestasis. The important practical implications of cholestasis are also briefly surveyed.

Alkaline phosphatase and cholestasis

The process of cholestasis in both man and rat leads in the majority of cases to the appearance of a biliary band in the electrophoresis of alkaline phosphatase isoenzymes. In this article, the biochemical nature and mode of formation of the biliary band is discussed, with reference to its appearance in cholestasis and other hepatobiliary diseases.

Liver plasma membrane: the source of high molecular weight alkaline phosphatase in human serum

This study presents biochemical, histochemical, morphological and immunological evidence that part of the high molecular weight alkaline phosphatase observed in the serum of patients with liver disease and particularly in cases of intrahepatic cholestasis or focal-, extrahepatic obstruction originates from the liver plasma membrane. The high molecular weight protein alkaline phosphatase complex contains several plasma membrane enzymes and behaves like a plasma membrane fragment after isopycnic density gradient ultracentrifugation in sucrose, cesium chloride and metrizamide. Electron microscopic examination revealed a triple-layered vesicle which retained alkaline phosphatase activity. Incubation of human liver cells with anti-serum against purified high molecular weight multienzyme complex resulted in fixation of antibodies on the plasma membrane as shown by positive plasma membrane fluorescence. These plasma membrane fragments in the serum are not of biliary origin.

Biochemistry of alkaline phosphatase isoenzymes

The review discusses the similarities and differences between the common isoenzymatic forms of ALP. Methods for separating, measuring, and purifying the isoenzymes on the basis of these differing properties are described. The evidence is reviewed for the existence of different genes coding for different isoenzymes, and the current state of knowledge is surveyed concerning the location, development, function, and regulation of the isoenzymes. Finally, some unusual forms of ALP which may appear in the circulation are described.