Hepatic microsomal cytochrome P450 system during experimental hookworm infection

Experimental infection of golden hamsters with the hookworm, Ancylostoma ceylanicum, caused a profound decline in the hepatic microsomal cytochrome P450 content. Concomitant decrease was also noticed in aminopyrine N-demethylase and benzo[a]pyrene hydroxylase activities. However, aniline hydroxylase activity was only marginally elevated during the infection. Microsomal markers, viz., cytochrome b5, NADH-cytochrome-c reductase, and glucose-6-phosphatase, were not significantly altered. Hepatic tissue exhibited an accumulation of lipids, especially phospholipids, triglycerides, and cholesterol, resulting in fatty necrosis around the central vein region. Isolated hepatic microsomes showed a decrease in phosphatidylcholine content. Impairment in hepatic mixed function oxidase (MFO) activities was further confirmed by prolongation in hexobarbital sleeping time and zoxazolamine-induced paralysis. The hepatic MFO system of A. ceylanicum-infected hamsters responded qualitatively and quantitatively in a manner similar to that of control hamsters, upon stimulation with selective chemical inducers like phenobarbitone and 3-methylcholanthrene. Kinetic and in vitro substrate binding studies revealed that for aminopyrine the substrate affinity and the maximum enzyme activity (Vmax) were decreased, while for aniline the binding affinity was decreased and the binding capacity was enhanced. Results indicate specific/selective impairment of the hepatic microsomal cytochrome P450 system during hookworm infection and may have many practical implications in toxicology and pharmacology.     

Morphofunctional disorders in the small intestine in acute occlusive ileus]

Activity of liminal and membrane enzymes and morphologic state of small intestinal mucosa were studied in experimental acute occlusive ileus in rats. It was established that degenerative alterations of intestinal mucosa epithelium above the site of obstruction are more pronounced than in the distal part. The activity of membrane enzymes (invertase) remained unaltered during 72 hours after the obturation, however, serious morphologic damage of the intestinal mucosa epithelium and sharp suppression of the liminal digestion were observed.     

Modifying effects of exercise on clinical course and biochemical response of the myocardium in influenza and tularemia in mice.

For a study of the interactions of strenuous physical exercise (daily swimming to exhaustion) and a viral as compared with a bacterial infection with regard to the clinical course and the biochemical response of the myocardium, influenza and tularemia of similar lethality were used in mice. In both infections, expected infection-induced catabolic alterations in the ventricular myocardium were evident 2 days before median lethality was achieved, with a more pronounced wasting in influenza than in tularemia. Exercise before inoculation (preconditioning) was beneficial in that the catabolic effects of both infections were limited and lethality in influenza was reduced. Thus, the myocardial protein-degrading effect of influenza did not occur with preconditioning, and oxidative tissue enzyme activities decreased less. In tularemia, cytochrome c oxidase activity was fully preserved with preconditioning, and activation of catalase was less pronounced. Exercise during ongoing infection counteracted the infection-induced decrease in the activities of glycolytic and oxidative enzymes in tularemia, but lethality and bacterial counts in the spleen were uninfluenced. Conversely, exhaustive exercise in influenza increased lethality and had no significant effect on cardiac enzymes. These exercise models caused no major alterations in activation of lysosomal enzymes (beta-glucuronidase and cathepsin D).     

Shigella infection in a SCID mouse-human intestinal xenograft model: role for neutrophils in containing bacterial dissemination in human intestine

Shigellae infect human intestine and cause intense inflammation and destruction of colonic and rectal mucosa. To model the interactions of shigella with human intestine in vivo, we have studied shigella infection in human intestinal xenografts in severe combined immunodeficient mice (SCID-HU-INT mice). Inoculation of shigella into human intestinal xenografts caused severe inflammation and mucosal damage, which was apparent as soon as 4 h following infection. Shigella infection was associated with human intestinal production of interleukin-1B (IL-1B) and IL-8 and a marked neutrophil influx into the graft. Depletion of neutrophils from SCID-HU-INT mice reduced inflammation in the human intestinal xenograft in response to shigella infection but failed to significantly alter tissue damage. However, the number of intracellular bacteria was more than 20-fold higher in the human intestinal xenografts from neutrophil-depleted SCID-HU-INT mice. Infection of human intestinal xenografts with an attenuated vaccine strain of shigella (CVD1203) induced lower levels of IL-1B and IL-8 than wild-type shigella and caused only moderate damage to the intestinal permeability barrier. Our studies establish the SCID-HU-INT mouse as a viable model for studying the interactions between shigella and human intestine and indicate that neutrophils are important for controlling the invasion of human intestine by shigella.     

Endotoxin-Induced Hepatic Damage in BCG-Infected Mice

Systemic infection of mice with Mycobacterium BCG leads to focal liver damage by producing many granulomas. By undefined mechanisms, this infection markedly enhances the animal's susceptibility to the lethal effect of endotoxin. Small doses of endotoxin given to BCG-infected mice were found to cause acute hepatic damage, as demonstrated by elevated activities of liver enzymes in serum and by morphologic alterations documented by light and electron microscopy and by histochemical technics. The morphologic alterations caused by endotoxin included glycogen depletion, mitochondrial swelling, disruption of the continuity of sinusoidal endothelium and focal injury characterized by marked vacuolization of hepatocytes and distension and fragmentation of rough endoplasmic reticulum. Histochemical studies revealed the apparent release of acid phosphatase from granules in the central portions of granulomas, and the release of β-glucuronidase from the cytoplasm of hepatocytes.     

Protective effect of date palm fruit extract (Phoenix dactylifera L.) on dimethoate induced-oxidative stress in rat liver

Nowadays, people’s exposure to chemical compounds such as organophosphorus insecticides is continuously on the rise more and more. Theses compounds have induced an excessive production of free radicals which are responsible for several cell alterations in the organism. Recent investigations have proved the crucial role of nutritional antioxidants to prevent the damage caused by toxic compounds. In this study, we investigate the role of date palm fruit extract (Phoenix dactylifera L.) in protection against oxidative damage and hepatotoxicity induced by subchronic exposure to dimethoate (20 mg/kg/day). Oral administration of dimethoate caused hepatotoxicity as monitored by the increase in the levels of hepatic markers enzymes (transaminases, alkaline phosphatase, gamma-glutamyl transferase and lactate dehydrogenase), as well as in hepatic malondialdehyde thus causing drastic alteration in antioxidant defence system. Particularly, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were found increased by dimethoate while catalase (CAT) activity was reduced significantly. These biochemical alterations were accompanied by histological changes marked by appearance of vacuolization, necrosis, congestion, inflammation, and enlargement of sinusoids in liver section. Pretreatment with date palm fruit extract restored the liver damage induced by dimethoate, as revealed by inhibition of hepatic lipid peroxidation, amelioration of SOD, GPx and CAT activities and improvement of histopathology changes. The present findings indicate that in vivo date palm fruit may be useful for the prevention of oxidative stress induced hepatotoxicity.     

Role of Endogenous and Exogenous Nitric Oxide on Intestinal Mucosa and Microflora in the Rat

In the present study the effects of exogenous and endogenous nitric oxide (NO) on intestinal bacteria and on the intestinal tissue integrity have been investigated in healthy rats and in rats receiving bacterial endotoxin (LPS). A segment of jejunum was taken in order to evaluate tissue damage and hematoxylin-eosin staining; microbiological studies were carried out collecting stool samples. Administration of LPS (5 mg kg^–1 i.v.) induced a moderate jejunal damage, which was completely prevented by N^G-nitro-L-arginine methyl ester (L-NAME, 5 mg kg^–1 s.c.), thus suggesting a damage of endogenous NO on the intestinal mucosa; sodium nitroprusside (SNP, 10 mg kg^–1 os) reduced significantly jejunal damage induced by LPS. Endogenous NO produced by the administration of LPS resulted to be cytotoxic for all examined aerobic and anaerobic bacteria, while exogenous NO, released from SNP, showed an inhibitory effect only on Entero. faecalis and E. coli growth. From our data, it seems reasonable to conclude that high local levels of NO are required in order to observe jejunal damage and cytotoxic effects on aerobic and anaerobic faecal flora.     

Adrenomedullin fails to reduce cadmium-induced oxidative damage in rat liver.

Recent studies have demonstrated that chronic cadmium administration induces oxidative stress. In the present study, we investigated the possible therapeutic effect of adrenomedullin, a potent antioxidant, in cadmium-induced morphological, ultrastructural and biochemical alterations. Two groups of rats were exposed to 100 ppm of CdCl(2) in drinking water for four weeks. One of these groups received 3000 ng/kg body weight of adrenomedullin (AdM) intraperitoneally during the last week. Hepatic oxidative stress markers were evaluated by changes in the amount of lipid peroxides and changes in the antioxidant enzyme activities, superoxide dismutase (SOD) and glutathione peroxidase (GPx) and glutathione reductase (GSH) levels. Hepatic damage score was significantly higher in Cd-administered rats than those of controls (p<0.005). Cd-induced ultrastructural changes in hepatocytes included focal parenchymal cell necrosis, dilatation of rough endoplasmic reticulum, proliferation of lysosomes and mitochondrial degeneration. Hepatic damage was accompanied by significant increase in tissue MDA level (p<0.05) and significant decrease in tissue GSH level (p<0.05), and SOD and GPx activities (p>0.05, p>0.005, respectively). Adrenomedullin failed to restore the light and electron microscopic, and biochemical changes. We conclude that although we administered a high dose of adrenomedullin, it failed to reduce cadmium-induced hepatic damage probably because of the irreversibility of Cd-induced hepatic injury.     

Experimental hymenolepiasis of rats: preliminary data on histopathological changes of visceral organs

Pathomorphological changes of intestine, liver, spleen and adrenals of rats experimentally infected with Hymenolepis diminuta are described 24 days post infection. Major structural alterations in intestinal wall include lesions of the mucosa, fusions of villi, damage of the epithelial layer and its replacement by flattened cells with pycnotic nuclei. In addition, tunica muscularis and tunica submucosa become thicker and there are numerous lymphocytes among enterocytes. At moderate infections, the changes in the spleen indicate activation of the lymphopoiesis and enhanced protective functions while, in heavily infected rats, the B zone of the spleen showed signs of emaciation. Liver histology of infected rats showed dilatation of sinusoids and the presence of destructive alterations in the parenchyma, necrotic cells and cells with pycnotic nuclei; in heavily infected animals, the necrotic cells were grouped in foci. In adrenal glands, alterations concern mostly zona fascicularis, which is interpreted as mobilization of cytoplasmic lipid inclusions in order to increase the intensity of the steroid hormone synthesis. The degree and character of histopathological changes depended on the intensity of infection.     

Outcomes of <Emphasis Type="Italic">Schistosoma mansoni</Emphasis> infection in outbred albino mice exposed to Larvin contaminant

The present study tested the hypothesis that mice exposed to Schistosoma mansoni and treated with the insecticide Larvin have an increased risk of accelerated liver damage. To investigate this hypothesis, adverse effects resulting from treatment with Larvin were compared between S. mansoni-exposed and nonexposed outbred albino mice. The effects of concurrent treatment with Larvin on the progress and outcomes of S. mansoni infection were assessed via macroscopic and microscopic examination of liver and spleen, evaluation of several hematological, biochemical and hepatic enzymes parameters, and effect on worm burden. Oral administration of 1/5 and 1/10 LD(50) of Larvin to S. mansoni-exposed mice induced (1) hepatomegaly and splenomegaly; (2) prominent lymphocytic aggregation in liver replacing large areas of bridging necrosis; (3) increased serum level of bilirubin and alanine aminotransferase-aspartate aminotransferase enzymes; (4) decreased serum level of albumin and total proteins; and (5) decreased RBC, hemoglobin content, leukocyte, and lymphocyte counts. No significant effect on worm burden or oviposition was noted as a result of Larvin treatment compared to controls. All doses used in mice either for infection with S. mansoni cercariae or treatment with Larvin resulted in dose dependent alterations in hepatic functions of the tested mice. These alterations were most profound in mice exposed to S. mansoni and receiving Larvin treatment. The present findings support our hypothesis and show that concurrent S. mansoni infection with exposure to Larvin adversely affect liver functions and seriously alter hematological, biochemical, and hepatic enzymes parameters in outbred albino mice. These findings warrant further investigation and reinforce the need to minimize exposure to insecticide in both natural field settings and the broader environment.     

Increased jejunal permeability in human obesity is revealed by a lipid challenge and is linked to inflammation and type 2 diabetes

Obesity and its metabolic complications are characterized by subclinical systemic and tissue inflammation. In rodent models of obesity, inflammation and metabolic impairments are linked with intestinal barrier damage. However, whether intestinal permeability is altered in human obesity remains to be investigated. In a cohort of 122 severely obese and non‐obese patients, we analyzed intestinal barrier function combining in vivo and ex vivo investigations. We found tight junction impairments in the jejunal epithelium of obese patients, evidenced by a reduction of occludin and tricellulin. Serum levels of zonulin and LPS binding protein, two markers usually associated with intestinal barrier alterations, were also increased in obese patients. Intestinal permeability per se was assessed in vivo by quantification of urinary lactitol/mannitol (L/M) and measured directly ex vivo on jejunal samples in Ussing chambers. In the fasting condition, L/M ratio and jejunal permeability were not significantly different between obese and non‐obese patients, but high jejunal permeability to small molecules (0.4 kDa) was associated with systemic inflammation within the obese cohort. Altogether, these results suggest that intestinal barrier function is subtly compromised in obese patients. We thus tested whether this barrier impairment could be exacerbated by dietary lipids. To this end, we challenged jejunal samples with lipid micelles and showed that a single exposure increased permeability to macromolecules (4 kDa). Jejunal permeability after the lipid load was two‐fold higher in obese patients compared to non‐obese controls and correlated with systemic and intestinal inflammation. Moreover, lipid‐induced permeability was an explicative variable of type 2 diabetes. In conclusion, intestinal barrier defects are present in human severe obesity and exacerbated by a lipid challenge. This paves the way to the development of novel therapeutic approaches to modulate intestinal barrier function or personalize nutrition therapy to decrease lipid‐induced jejunal leakage in metabolic diseases. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Sodium-calcium exchange and sarcolemmal enzymes in ischemic rabbit hearts

We have investigated alterations in sarcolemmal function that occur during myocardial ischemia. Rabbit ventricles were incubated at 37 degrees C for time periods ranging from 5 min to 2 h. The ischemic tissue was homogenized, and activities of the sarcolemmal enzymes Na+-K+-ATPase, K+-p-nitrophenylphosphatase (K+-pNPPase), and adenylate cyclase were measured in the crude homogenate. Na+-K+-ATPase and K+-pNPPase were substantially inhibited after only 10 min of ischemia, and activities for all three enzymes declined progressively up to 1 h of ischemia, when activities were 37-59% of control. Highly purified sarcolemmal membranes prepared from control tissue and myocardium that had been made ischemic for 1 h showed similar purification of sarcolemmal enzymes, passive Ca2+ binding, and passive permeability to Ca2+. However, the velocity of Na+-Ca2+ exchange in ischemic sarcolemmal vesicles was reduced approximately 50% due to a reduction in Vmax. Although the parallel decline in activities of several sarcolemmal functions might suggest a change in membrane structure, phospholipid and cholesterol contents in ischemic sarcolemma were the same as control.     

Scanning electronmicroscopy of the jejunum in enteritis necroticans

Intestinal tissue resected at laparotomy from patients in Papua New Guinea at various clinical stages of enteritis necroticans, locally known as pig-bel, has been examined under the scanning electronmicroscope. Evidence obtained from parallel studies of experimental infection in pigs is presented. Progressive destruction of the intestinal mucosa was seen during the course of the disease in man. Numerous filamentous rods morphologically consistent with the appearance of Clostridium perfringens type C, were seen to be attached the affected areas of gut and were associated with the necrotic tissue. The mechanism of pathogenicity includes a stage of attachment to the surfaces of jejunal villi, local multiplication, and the production of beta toxin which may be protected from tryptic digestion by the inadequacy of pancreatic protease production in susceptible subjects and by the ingestion of a trypsin inhibitor. The association of the condition with pork feasting is discussed.     

The occupation of intestinal epithelium by Trichinella spiralis in BALB/C mice is not associated with local manifestation of apoptosis related factors

Trichinella spiralis actively passes through the epithelial cells of the intestinal mucosa but morphologically, these cells do not manifest apparent damage. The possible activation of apoptotic mechanisms in the small intestine mucosa after infection with larvae and adults of Trichinella spiralis was explored by immunohistochemistry. Sporadic individual cells of normal intestinal epithelium showed activation of caspase-3, increased expression AIF, or Bax. The larval stage of intestinal trichinellosis was characterized by distortion of cells on the villus tips that were strongly reactive to caspase-3, Bax, and survivin antibodies. There was a transient loss of the survivin expression on the brush border of the epithelial cells at 15-h post infection, which reappeared on the fifth day. Bcl-2 changed its normal apical distribution and re-localized to the basal part of the epithelial cells. No significant changes of expression of the selected apoptosis-related proteins were observed in the intestinal epithelial cells immediately surrounding the worms. The presence of Trichinella affects intestinal epithelial cells, but unlike in muscle cells, invading them does not initiate apoptotic factors activation.     

A family of cathepsin B cysteine proteases expressed in the gut of the human hookworm, Necator americanus

mRNAs encoding cathepsin B-like cysteine proteases (CatBs) are abundantly expressed in the genomes of blood-feeding nematodes. Recombinant CatBs have been partially efficacious in vaccine trials in animal models of hookworm infection, supporting further investigation of these enzymes as new control tools. We recently described a family of four distinct CatBs (Na-CP-2, -3, -4, -5) from the human hookworm, Necator americanus. Here we show that these N. americanus CatBs form a robust clade with other hookworm CatBs and are most similar to intestinal CatBs from Haemonchus contortus. All four mRNAs (Na-cp-2, -3, -4 and -5) are up-regulated during the transition from a free-living larva to a blood-feeding adult worm and are also expressed in gut tissue of adult N. americanus that was dissected using laser microdissection microscopy. Recombinant Na-CP-3 was expressed in soluble, secreted form in the yeast Pichia pastoris, while Na-CP-2, -4 and -5 were expressed in insoluble inclusion bodies in Escherichia coli. Recombinant Na-CP-3 was not catalytically active when secreted by yeast but underwent auto-activation to an active enzyme at low pH in the presence of dextran sulphate. Activated Na-CP-3 digested gelatin and cleaved the fluorogenic substrate Z-Phe-Arg-aminomethylcoumarin (AMC) but not Z-Arg-Arg-AMC. Recombinant Na-CP-3 did not digest intact hemoglobin but digested globin fragments generated by prior hydrolysis with N. americanus aspartic hemoglobinases. Antibodies raised in mice to all four recombinant proteins showed minimal cross-reactivity with each other, and each antiserum bound to the intestine of adult N. americanus, supporting the intestinal expression of their mRNAs. These data show that N. americanus expresses a family of intestinal CatBs, many of which are likely to be involved in nutrient acquisition and therefore are potential targets for chemotherapies and vaccines.     

广东省湛江市农村人群肠道蠕虫感染调查

目的了解湛江市农村人群肠道蠕虫感染现状。方法随机采集村民新鲜粪便，用直接涂片法及饱和盐水浮聚法检查虫卵，用盐酸左旋咪唑驱虫法检查感染钩虫种类。结果粪检190人，虫卵阳性78人，总感染率为41．1％。检出3种肠道蠕虫卵，其中钩虫感染率25．8％，蛔虫感染率12．1％，鞭虫感染率10．5％，有2种或3种虫卵阳性率为6．8％；不同地点各虫感染率不同；钩虫以50—70岁人群感染率较高，蛔虫、鞭虫以20岁以下人群常见；女性的钩虫感染率明显高于男性。药物驱虫后检获有十二指肠钩虫成虫、美洲钩虫成虫及雄性蛔虫，其中，十二指肠钩虫占钩虫比例87．4％，美洲钩虫占钩虫比例12．6％。结论湛江市农村人群感染蛔虫、鞭虫及钩虫常见，其中以钩虫感染最为严重。钩虫感染率较高与旱作生产生活方式密切相关。十二指肠钩虫在该地钩虫流行中占了重要地位。     

Studies of hepatic mitochondrial structure and function: morphometric and biochemical evaluation of in vivo perturbation by arsenate.

Ultrastructural morphometric and biochemical studies were conducted on hepatic mitochondria from control rats and rats treated in vivo with arsenate to examine changes in interrelationships between mitochondrial structure and biochemical functions. Morphometric analysis disclosed an over-all 1.2-fold increase in the relative mitochondrial volume density and 1.4-fold increase in the surface density of the inner mitochondrial membrane of arsenate-exposed rats. These structural changes were associated with a 1.5-fold increase in 14C-leucine incorporation into all mitochondrial proteins, which was primarily associated with the acid-insoluble membranous fraction. Mitochondria from arsenate-treated rats showed a marked disruption of normal conformational behavior with depression of nicotinamide adenine dinucleotide (NAD)-linked substrate oxidation and a resulting in vivo increase in the mitochondrial [NAD] to [NADH] ratio. Observed changes in mitochondrial membranes from arsenate exposure also resulted in 1.5- to 2-fold increases in the specific activities of the membrane marker enzymes monoamine oxidase, cytochrome oxidase, and Mg2+-ATPase. Activity of malate dehydrogenase, which is localized in the mitochondrial matrix, was unchanged. The results of this study demonstrate a positive quantitative in vivo correlation between mitochondrial structure and function and indicate a marked dependency upon membrane integrity for normal maintenance of the specific biologic activities performed by this organelle in vivo.