Aluminum in total parenteral nutrition solutions produces portal inflammation in rats

Histopathological and ultra-structural investigation of the damaging effects of hypoinsulinemia, hyper glycaemia and oxidative stress caused by parenteral nutrition combined with fasting on the small intestine of rabbits

BACKGROUND AND STUDY AIMS

Parenteral nutrition (PN) is a life-saving practice when the use of the gastrointestinal tract is not appropriate. Despite its great benefits, however, PN may cause several complications. In this study, we conducted histopathological and ultra-structural examinations of the effect of PN combined with starvation on the small intestines of rabbits.

MATERIALS AND METHODS

Rabbits were divided into four groups. A fasting + PN group was left completely unfed and received all its daily required energy by PN through an intravenous central catheter. An oral feeding + PN group received half the necessary daily calories by oral feeding and the other half through PN. A semi-starvation group received only half the necessary daily calories by oral feeding and no PN. The fourth group, serving as a control, was supplied with its entire daily energy requirements through oral feeding. After 10 days, the rabbits were euthanized. Blood and small intestine tissue samples were collected from all groups. Blood samples were biochemically analysed, and tissue samples were examined by light and transmission electron microscopy.

RESULTS

The fasting + PN group exhibited lower insulin levels, higher glucose levels, and increased systemic oxidative stress than the other groups. Ultra-structural and histopathological examinations revealed a significant increase in apoptotic activity in this group's small intestines and a significant decrease in villus length and crypt depth. Severe damage to the intracellular organelles and nuclei of enterocytes was also observed.

CONCLUSION

PN combined with starvation appears to cause apoptosis in the small intestine due to oxidative stress and hyperglycaemia with hypoinsulinemia, with destructive effects on small intestine tissue. Adding enteral nutrition to PN may reduce these destructive effects.

Histopathologic and electron microscopic investigation of the damage to liver tissue caused by parenteral nutrition combined with starvation in rabbits

AIM OF THE STUDY

To conduct a histopathological examination of the damaging effects of the combination of parenteral nutrition (PN) with starvation on liver tissue using transmission electron and light microscopy.

MATERIAL AND METHODS

Four groups (n = 14 each) consisting of equal numbers of female and male New Zealand rabbits were formed: a group left completely unfed and receiving full-dose PN (full-dose PN group), a group provided with feed covering half its nutritional needs and receiving half-dose PN (half-dose PN + oral nutrition group), a group provided with feed covering half its nutritional needs (semi-starvation group), and a group provided with feed covering all its nutritional needs (control group). After 10 days, all rabbits were weighed, anesthetized, and euthanized, and liver tissue samples were collected. Histopathologic examination was performed by a surgical pathologist blinded to the experimental groups. Portal inflammation, ballooning degeneration, apoptosis and fibrosis were evaluated and statistically analyzed.

RESULTS

Severe portal inflammation, moderate portal fibrosis, slight ballooning degeneration, and moderate apoptosis were found in the full-dose PN group. Mild portal inflammation, fibrosis and mild apoptosis were found in the half-dose PN + oral nutrition group. The results of the other two groups were found normal.

CONCLUSIONS

Liver damage caused by PN combined with starvation can be devastating. The damage can be minimized by combining PN with enteral nutrition.

Investigation of the cardiotoxic effects of parenteral nutrition in rabbits

INTRODUCTION

Parenteral nutrition (PN) is used for the intravenous delivery of nutrients to patients who cannot take food orally. However, it is not clear whether PN also negatively impacts cardiac tissue. The present empirical study investigated the cardiac effects of PN in rabbits.

METHODS

The effects of PN were examined in three groups of rabbits: animals in the PN + fasting group (n = 14) had been fully fasted before receiving a full PN dose via an intravenous central catheter; the PN + oral feeding group (n = 14) received half of the daily calorie requirement as a half dose of PN via an intravenous central catheter; the third group consisted of controls (n = 14) with full enteral feeding and full enteral fluid intake with no PN and no central venous catheter. At the end of the 10-day study period, the rabbits were subjected to echocardiographic examination and euthanized. Blood and tissue samples were obtained from all groups. DNA was isolated from nucleated blood cells. Tissue samples were examined by both light and electron microscopy, relative telomere length was determined from DNA, and blood samples were analyzed biochemically.

RESULTS

At the end of the study, there were no statistically significant differences in weight change between the three groups. Echocardiography revealed minimally impaired diastolic function in the PN + fasting group compared to the other groups. Biochemical and histopathological analyses, relative telomere length determination, and electron micrographs showed significant cardiac damage in the PN + fasting group but not in the PN + oral feeding group or the control group. The blood biochemical analyses showed hyperglycemia and a low insulin level in the PN + fasting group but not in the other two groups.

CONCLUSIONS

A combination of PN and fasting may damage the cardiac muscle cells of rabbits via a mechanism involving hyperglycemia and oxidative stress. Additional enteral feeding may protect against the destructive effects of PN on cardiac tissue.

Aluminum Exposure from Parenteral Nutrition: Early Bile Canaliculus Changes of the Hepatocyte

Background: Neonates on long-term parenteral nutrition (PN) may develop parenteral nutrition-associated liver disease (PNALD). Aluminum (Al) is a known contaminant of infant PN, and we hypothesize that it substantially contributes to PNALD. In this study, we aim to assess the impact of Al on hepatocytes in a piglet model. Methods: We conducted a randomized control trial using a Yucatan piglet PN model. Piglets, aged 3–6 days, were placed into two groups. The high Al group (n = 8) received PN with 63 µg/kg/day of Al, while the low Al group (n = 7) received PN with 24 µg/kg/day of Al. Serum samples for total bile acids (TBA) were collected over two weeks, and liver tissue was obtained at the end of the experiment. Bile canaliculus morphometry were studied by transmission electron microscopy (TEM) and ImageJ software analysis. Results: The canalicular space was smaller and the microvilli were shorter in the high Al group than in the low Al group. There was no difference in the TBA between the groups. Conclusions: Al causes structural changes in the hepatocytes despite unaltered serum bile acids. High Al in PN is associated with short microvilli, which could decrease the functional excretion area of the hepatocytes and impair bile flow.

Diethylhexylphthalate Extracted by Typical Newborn Lipid Emulsions From Polyvinylchloride Infusion Systems Causes Significant Changes in Histology of Rabbit Liver

BACKGROUND

Looking for a candidate substance inducing hepatobiliary dysfunction under parenteral nutrition (PN) in newborns, we recently discovered that newborn infusions extract large amounts of the plasticizer diethylhexylphthalate (DEHP) from commonly used polyvinylchloride (PVC) infusion lines. This plasticizer is well known to be genotoxic and teratogenic in animals and to cause changes in various organs and enzyme systems even in humans. The aim of this study was to examine the effect of DEHP, extracted in the same way and in the same amount as in newborns, on livers of young rabbits.

METHODS

Prepubertal rabbits received lipid emulsion through central IV lines continuously for 3 weeks either via PVC or polyethylene (PE) infusion systems. Livers were examined after 1 and 3 weeks by light and electron microscopy.

RESULTS

By light microscopy, hydropic degeneration, single-cell necrosis, fibrosis, and bile duct proliferation were observed more in the PVC group. Electron microscopy revealed multiple nuclear changes, clusters and atypical forms of peroxisomes, proliferation of smooth endoplasmic reticulum, increased deposition of lipofuscin, and a mild perisinusoidal fibrosis only in the PVC group. These changes, which are generally regarded as reaction upon a toxic stimulus, could be exclusively attributed to DEHP.

CONCLUSIONS

This investigation proved that DEHP produces toxin-like changes in livers of young rabbits in the same dose, duration, and method of administration as in newborn infants. For this reason, it is likely that DEHP is the substance that causes hepatobiliary dysfunction in newborns under PN. Possible modes of action of DEHP are proposed.

Aluminum and Phthalates in Calcium Gluconate: Contribution From Glass and Plastic Packaging

BACKGROUND

Aluminum contamination of parenteral nutrition solutions has been documented for 3 decades. It can result in elevated blood, bone, and whole body aluminum levels associated with neurotoxicity, reduced bone mass and mineral content, and perhaps hepatotoxicity. The primary aluminum source among parenteral nutrition components is glass-packaged calcium gluconate, in which aluminum concentration in the past 3 decades has averaged approximately 4000 μg/L, compared with <200 μg/L in plastic container-packaged calcium gluconate. A concern about plastic packaging is leaching of plasticizers, including phthalates, which have the potential to cause endocrine (male reproductive system) disruption and neurotoxicity.

METHODS

Aluminum was quantified in samples collected periodically for more than 2 years from 3 calcium gluconate sources used to prepare parenteral nutrition solutions; 2 packaged in glass (from France and the United States) and 1 in plastic (from Germany); in a recently released plastic-packaged solution (from the United States); and in the 2 glass containers. Phthalate concentration was determined in selected samples of each product and leachate of the plastic containers.

RESULTS

The initial aluminum concentration was approximately 5000 μg/L in the 2 glass-packaged products and approximately 20 μg/L in the plastic-packaged product, and increased approximately 30%, 50%, and 100% in 2 years, respectively. The aluminum concentration in a recently released Calcium Gluconate Injection USP was approximately 320 μg/L. Phthalates were not detected in any calcium gluconate solutions or leachates.

CONCLUSIONS

Plastic packaging greatly reduces the contribution of aluminum to parenteral nutrition solutions from calcium gluconate compared with the glass-packaged product.

Aluminum as a toxicant

Although aluminum is the most abundant metal in nature, it has no known biological function. However, it is known that there is a causal role for aluminum in dialysis encephalopathy, microcytic anemia, and osteomalacia. Aluminum has also been proposed to play a role in the pathogenesis of Alzheimer’s disease (AD) even though this issue is controversial. The exact mechanism of aluminum toxicity is not known but accumulating evidence suggests that the metal can potentiate oxidative and inflammatory events, eventually leading to tissue damage. This review encompasses the general toxicology of aluminum with emphasis on the potential mechanisms by which it may accelerate the progression of chronic age-related neurodegenerative disorders.

Damaging Effects of Total Parenteral Nutrition Formula on Vascular Endothelium

OBJECTIVES

Sepsis in one of the most serious complications that can occur during total parenteral nutrition (TPN) procedures. In this experimental study, we investigated the effects of TPN, with or without lipid emulsion, on vascular endothelial damage.

METHODS

In total, 50 rabbits were used, divided into 5 groups of 10 each. TPN with lipids (group 1), TPN without lipids (group 2), and 0.09% saline (group 3) were given for 10 days via a central venous catheter. Group 4 received no treatment other than placement of a central venous catheter for 10 days. Group 5 was a control group. At the end of day 10, rabbits were sacrificed and tissue samples of liver, kidney, and inferior vena cava were prepared and examined by immunohistochemical methods for vascular cellular adhesion molecule (VCAM)-1 expression.

RESULTS

In tissue sections of liver, kidney, and inferior vena cava, VCAM-1 activity was increased prominently in TPN with and without lipids compared with the control group. VCAM-1 activity in the TPN with lipids group was decreased versus the TPN without lipids group (P > 0.05).

CONCLUSIONS

The TPN procedure results in vascular endothelial cell damage not only in the vein where the solution is introduced but also in other parts of the vascular system. Even if it is not statistically significant, lipids in the TPN formula may decrease this endothelial cell damage, as shown by immunohistochemistry.

Reduced aluminum contamination decreases parenteral nutrition associated liver injury

PURPOSE

Parenteral nutrition-associated cholestasis remains a significant problem, especially for the surgical neonates. Aluminum is a toxic element known to contaminate parenteral nutrition. We hypothesize that parenterally administered aluminum causes liver injury similar to that seen in parenteral nutrition-associated cholestasis.

METHODS

Twenty 3- to 6-day-old domestic pigs were divided into 5 equal groups. A control group received daily intravenous 0.9% NaCl. Each subject in experimental groups received intravenous aluminum chloride at 1500 μg kg(-1) d(-1) for 1, 2, 3, or 4 weeks. At the end of the study, blood was sampled for direct bilirubin and total bile acid levels. Liver, bile, and urine were sampled for aluminum content. Liver tissue was imaged by transmission electron microscopy for ultrastructural changes.

RESULTS

Transmission electron microscopy revealed marked blunting of bile canaliculi microvilli in all experimental subjects but not the controls. Serum total bile acids correlated with the duration of aluminum exposure. The hepatic aluminum concentration correlated with the duration of aluminum exposure.

CONCLUSIONS

Parenterally infused aluminum resulted in liver injury as demonstrated by elevated bile acids and by blunting of the bile canaliculi microvilli. These findings are similar to those reported in early parenteral nutrition-associated liver disease.

Parenteral aluminum induces liver injury in a newborn piglet model

PURPOSE

Parenteral nutrition-associated cholestasis remains a significant problem, especially for the surgical neonate. Aluminum is a toxic element known to contaminate parenteral nutrition. We hypothesize that parenterally administered aluminum causes liver injury similar to that seen in parenteral nutrition-associated cholestasis.

METHODS

Twenty 3- to 6-day-old domestic pigs were divided into 5 equal groups. A control group received daily intravenous 0.9% sodium chloride. Each subject in experimental groups received intravenous aluminum chloride at 1500 μg/kg per day for 1, 2, 3, or 4 weeks. At the end of the study, blood was sampled for direct bilirubin and total bile acid levels. Liver, bile, and urine were sampled for aluminum content. Liver tissue was imaged by transmission electron microscopy for ultrastructural changes.

RESULTS

Transmission electron microscopy revealed marked blunting of bile canaliculi microvilli in all experimental subjects but not the controls. Serum total bile acids correlated with the duration of aluminum exposure. The hepatic aluminum concentration correlated with the duration of aluminum exposure.

CONCLUSIONS

Parenterally infused aluminum resulted in liver injury as demonstrated by elevated bile acids and by blunting of the bile canaliculi microvilli. These findings are similar to those reported in early parenteral nutrition-associated liver disease.

A new insight on Al-maltolate-treated aged rabbit as Alzheimer's animal model

Lack of an adequate animal model for Alzheimer's disease (AD) has limited an understanding of the pathogenesis of the disease and the development of therapeutic agents targeting key pathophysiological processes. There are undoubtedly few satisfactory animal models for exploring therapies targeting at amyloid beta (Abeta) secretion, deposition, aggregation, and probably the inflammatory response. However, an understanding of the complex events--tau, Abeta, oxidative stress, redox active iron, etc.--involved in the neuronal cell loss is still unclear due to the lack of a suitable animal model system. The use of neurotoxic agents particularly aluminum-organic complexes, especially Al-maltolate, expands the scope of AD research by providing new animal models exhibiting neurodegenerative processes relevant to AD neuropathology. Examination of different species of aged animals including the rapidly advancing transgenic mouse models revealed very limited AD-like pathology. Most other animal models have single event expression such as extracellular Abeta deposition, intraneuronal neurofilamentous aggregation of proteins akin to neurofibrillary tangles, oxidative stress or apoptosis. To date, there are no paradigms of any animal in which all the features of AD were evident. However, the intravenous injection of Al-maltolate into aged New zealand white rabbits results in conditions which mimics a number of neuropathological, biochemical and behavioral changes observed in AD. Such neurodegenerative effects include the formation of intraneuronal neurofilamentous aggregates that are tau positive, immunopositivity of Abeta, presence of redox active iron, oxidative stress and apoptosis, adds credence to the value of this animal model system. The use of this animal model should not be confused with the ongoing controversy regarding the possible role of Al in the neuropathogenesis, a debate which by no means has been concluded. Above all this animal model involving neuropathology induced by Al-maltolate provides a new information in understanding the mechanism of neurodegeneration.

Aluminum: impacts and disease

Aluminum is the most widely distributed metal in the environment and is extensively used in modern daily life. Aluminum enters into the body from the environment and from diet and medication. However, there is no known physiological role for aluminum within the body and hence this metal may produce adverse physiological effects. The impact of aluminum on neural tissues is well reported but studies on extraneural tissues are not well summarized. In this review, the impacts of aluminum on humans and its impact on major physiological systems are summarized and discussed. The neuropathologies associated with high brain aluminum levels, including structural, biochemical, and neurobehavioral changes, have been summarized. In addition, the impact of aluminum on the musculoskeletal system, respiratory system, cardiovascular system, hepatobiliary system, endocrine system, urinary system, and reproductive system are discussed.

Pro-inflammatory effects of aluminum in human glioblastoma cells

Inflammatory events have been associated with senile plaques, one of the pathological hallmarks of Alzheimer's disease (AD). It is believed that aggregated beta-amyloid (betaA) proteins, which form the core of these plaques, may be responsible for triggering the inflammatory reaction. In the present study, the ability of aluminum (Al) to initiate similar inflammatory events was investigated in a human glioblastoma cell line. A 6-day exposure to either lipopolysaccharide (LPS) or aluminum sulfate caused a significant increase in the rate of proliferation of the glioblastoma cells. Both treatments also caused activation of the immune-responsive transcription factor NF-kappaB although there were time-related differences. The levels of secreted cytokines, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) were both increased by the LPS treatment although exposure to Al decreased the secretion of the former while elevating the levels of the latter. These events may be due to the activation of glial cells and subsequent stress response to either Al complexes or LPS. Although exposure to either stress factor caused a stimulation of inflammatory markers, there were time-dependent differences in the response. This may reflect the ability of the cells to discern different stress factors and thus orchestrate an innate immune response profile distinct to each immunogen.

Effects of fulvic acid on the bioavailability of rare earth elements and GOT enzyme activity in wheat (Triticum aestivum)

Fulvic acid (FA) was extracted and purified from natural soil and the effects of such FA on the bioaccumulation of rare earth elements (REEs, La3+, Gd3+ and Y3+) in wheat seedling were investigated. The results indicated that low concentration of FA (<0.4 mg C/l to root, <0.7 mg C/l to tops (stem and leaves)) could increase the bioaccumulation values of REEs in wheat, but when the concentration of FA was high (>0.4 mg C/l to root, >1.5 mg C/l to tops) the bioaccumulation values were decreased. Kinetic experimental results suggested that bioaccumulation values of REEs in roots for 30 days were correlated with the kinetic linear growth equation, and correlation coefficients were higher than 0.861. The kinetic bioaccumulation pattern of REEs in tops was different from that in root. The bioaccumulation values of REEs in wheat root were much higher than in wheat tops. Variations of glutamic oxaloacetic transaminase (GOT) enzyme activities in wheat root and tops were determined. A good correlation existed between the bioaccumulation values of REEs and GOT enzyme activities, and the correlation coefficients were higher than 0.922. GOT is an important parameter influencing the bioavailability of REEs.

Mechanisms by which metals promote events connected to neurodegenerative diseases

Although the exact causative phenomenon responsible for the onset and progression of neurodegenerative disorders is at present unresolved, there are some clues as to the mechanisms underlying these chronic diseases. This review addresses mechanisms by which endogenous or environmental factors, through interaction with redox active metals, may initiate a common cascade of events terminating in neurodegeneration.

Interference of aluminium on iron metabolism in erythroleukaemia K562 cells

It has been suggested that aluminium (Al) has a deleterious effect on erythropoiesis. However, there is still uncertainty as to its action mechanism. The present work was designed to determine how Al could affect the iron (Fe) metabolism in the human erythroleukaemia cell line K562. These cells, that express surface transferrin receptors (TfRs), were induced to erythroid differentiation by either haemin or hydroxyurea in 72 h cultures in media containing apotransferrin (apoTf). In the presence of aluminium citrate, the number of benzidine-positive cells decreased 18% when the cultures were induced by haemin, and 30% when hydroxyurea was the inducer. Cell viability was always unaffected. From competition assays, surface binding of 125I-Tf-Fe2 was found to be inversely related (p < 0.05) to Tf-Al2 concentration (from 2.5 to 10 nM). The dissociation constants (Kd) of the binding reaction between TfRs and the ligands Tf-Fe2 and Tf-Al2 were calculated. Kd values of the same order of magnitude demonstrated that TfR has a similar affinity for Tf-Fe2 (Kd = 1.75 x 10(-9) M) and Tf-Al2 (Kd = 1.37 x 10(-9) M). The number of surface TfRs, measured by kinetic 125I-Tf-Fe2 binding assays, was higher in induced cells cultured in the presence of Al. Nevertheless, in spite of the inhibition of cell haemoglobinization observed, 59Fe incorporation values were not different from those measured in control cultures for 72 h. As a consequence, it can be suggested that cellular Fe utilisation, and not Fe uptake, might be the main metabolic pathway impaired by Al.

The effects of acetylsalicylic acid, interferon-alpha, and vitamin E on prevention of parenteral nutrition-associated cholestasis: an experimental study

BACKGROUND

Cholestasis is one of the major complications of parenteral nutrition. The purpose of this experimental study was to detect the effects of acetylsalicylic acid (ASA), vitamin E (Vit E), and interferon-alpha (IFN-alpha) on prevention of parenteral nutrition-associated cholestasis.

METHODS

Ten experimental groups, each consisting of 10 4-week-old Wistar albino rats, were formed: control 10- and 20-day groups (C10 and C20), parenteral nutrition-only 10- and 20-day groups (T10 and T20), ASA-supplemented parenteral nutrition 10- and 20-day groups (TA10 and TA20), Vit E-supplemented parenteral nutrition 10- and 20-day groups (TE10 and TE20), and IFN-alpha-supplemented 10- and 20-day groups (TF10 and TF20). Acetylsalicylic acid, Vit E, and IFN-alpha were administered in the parenteral nutrition solution through an intraperitoneal route. At the end of the study, serum total bile acids, serum aspartate and alanine aminotransferases, and alkaline phosphatase were measured biochemically. In addition, the histopathologic findings of cholestasis were evaluated by using a morphologic portal inflammation index.

RESULTS

Although the difference in the serum levels of transferases and alkaline phosphatase was not significant among all groups (p > 0.05), it was significant in total bile acid levels (p < 0.05). There was also a significant correlation between the histopathologic changes of the liver and serum total bile acid concentrations (p < 0.05). Portal inflammation in varying degrees was seen in all experimental groups, but not in the control groups. Serum total bile acid concentrations in parenteral nutrition groups receiving ASA were significantly lower than those in the parenteral nutrition-only group (p < 0.01). Although Vit E-supplemented parenteral nutrition was effective in preventing the development of cholestasis in the 10-day group (p < 0.05), it was not effective in the 20-day group when compared with incidence of cholestasis in the parenteral nutrition-only group (p > 0.05). Conversely, IFN-alpha-supplemented parenteral nutrition had no effect on cholestasis in the 10-day group (p > 0.05) but lowered cholestasis in the 20-day group when compared with incidence the parenteral nutrition-only group (p < 0.05).

CONCLUSION

Our results indicate that acetylsalicylic acid may be beneficial in preventing, and (alpha-interferon in treating, parenteral nutrition-associated cholestasis.