Probiotics can treat hepatic
encephalopathy
S. F. Solga
Johns Hopkins Hospital, Baltimore, USA
Summary Hepatic encephalopathy (HE) is a common and dreaded complication of liver disease. The effects of HE can range from minimal to life threatening. Even ‘minimal HE’ causes major dysfunction in many aspects of daily living.
The exact pathogenesis of HE remains unknown. However, the products of gut flora metabolism are universally recognized as critical. Present treatments for HE include the cathartic agent lactulose and poorly absorbable antibiotics. While effective, these treatments incur numerous side-effects and cost.
Probiotics are viable bacteria given orally to improve health. Probiotics have multiple mechanisms of action that could disrupt the pathogenesis of HE and may make them superior to conventional treatment.
ª 2003 Elsevier Science Ltd. All rights reserved.
BACKGROUND/SIGNIFICANCE
Disease and pathogenesis
Hepatic encephalopathy (HE) is a common and serious complication of chronic liver disease. This complex neuropychiatric syndrome has been defined as ‘a dis-turbance in central nervous system function because of hepatic insufficiency’ (1). At least 50–70% of patients with cirrhosis will demonstrate abnormalities on py-schometric testing (2,3), and many will have significant functional impairment. Encephalopathy can occur in patients with both acute and chronic liver disease, and can be clinically overt or less apparent.
‘Minimal encephalopathy’ is a term that describes patients with chronic liver disease who have no clinical symptoms of brain dysfunction, but perform substan-tially worse on pyschometric tests compared to healthy controls (4). An extensive body of research has consis-tently documented cognitive deficits in these patients, including impaired psychomotor speed, attention, and
visual perception. Predictably, such impairments lead to major difficulties in safely performing routine activities of life. Landmark work by Schomerus et al. (5) demon-strated that 60% of cirrhotics with minimal HE were unfit to drive, and an additional 25% were possibly unfit to drive. In agreement with this finding, other investigators have found impaired earning capacity, particularly amongst blue-collar workers requiring psy-chomotor skills in order to perform their jobs (6). Fur-ther, extensive work using a 136 part ‘sickness impact profile’ (a generic, non-disease-specific quality of life questionnaire) found that minimal HE has major impact on all aspects of a patient’s life (7).
Clinically apparent encephalopathy has been subdi-vided into a semi-quantative grading scheme ranging from mild (grade I) to severe (grade II–IV). According to the West Haven Criteria (8), grade I encephalopathy in-dicates a patient with ‘trivial lack of awareness, euphoria or anxiety, shortened attention span, and impaired per-formance of addition’. At times, clinicians may have difficulty distinguishing these patients from patients with minimal encephalopathy.
The pathogenesis of HE is unknown, but is almost certainly multi-factorial. Gut-derived nitrogenous sub-stances are universally acknowledged to play a major role. Specifically, ammonia is thought to be a critical factor in the pathogenesis. While ammonia is produced by many tissues, most results from the activity of urease
Received 3 September 2002 Accepted 11 November 2002
Correspondence to:Steven F. SolgaMD, 600 North Wolfe Street, Blalock 4, Division of Gastroenterology, Johns Hopkins Hospital, Baltimore, MD 21205, USA. Phone: 410-502-7729; Fax: 410-955-2108;
producing gut flora and is released into the portal vein after absorption by the intestinal epithelium. Ammonia is converted into urea in the liver, carried to the kidneys, and then excreted into the urine. Normally a very effi-cient process, humans excrete over 20 pounds of urea a year (9) and first pass hepatic clearance of ammonia is around 80% (10). See Fig. 1.
Further understanding of urease and ammonia is im-portant to the pathophysiology of HE and potential treatments. Urease-producing bacteria exist in abun-dance in the gut of ‘ureolytic’ animals (11). Ureolytic animals, including humans, excrete nitrogenous waste primarily via urea in the urine. Urease is a bacterial enzyme that catalyzes the hydrolysis of urea to carba-mate and ammonia (12). Bacteria from many different genera produce urease, and its expression can be nitro-gen regulated, urea inducible, or constitutive (13). Ure-ase-producing bacteria are frequently gram negative Enterobacterceae. The potential therapeutic conse-quences of blocking urease activity were established decades ago by demonstrations that injection of anti-urease antibodies reduced ammonia production and improved encephalopathy (14). Such ‘immunization’ against urease, however, caused many side effects and was ultimately abandoned (15).
Ammonia is a weak base with a pKa of 9.25 (16).
Therefore, decreases in lumenal pH increases the ratio of ionized to unionized ammonia, and decreases passive non-inonic diffusion. As a result, less ammonia is ab-sorbed into the portal blood and more is excreted in feces (17). Further, lower lumenal pH itself reduces the degradation of nitrogenous compounds (proteins and amino acids) and production of ammonia (18).
The physiologic balance of ammonia production and clearance is disrupted on multiple levels in patients with cirrhosis, resulting in HE. An extensive body of evidence reports that cirrhotics harbor more gut urease-active bacteria than controls (19), and that this leads directly to increased intestinal hydrolysis of urea and absorption of nitrogenous products (20). Altered small intestinal
dysmotility frequently accompanies cirrhosis (21) and likely exacerbates this problem. Further, increasedportal
ammonia results in markedly increasedsystemic ammo-nia because of: (1) impaired hepatic processing of am-monia and (2) the shunting of portal blood away the liver. Finally, ammonia crosses the blood–brain barrier more readily patients with HE (22), where it acts on impaired astroctyes and results in a cascade of patho-pysiologic neurochemical events (23). See Fig. 2.
Other gut-derived toxins may also play a role in the pathogenesis of HE (24). For example, intestinal flora may produce benzodiazepine-like substances (25) or mercaptans (26) which can be additive or synergistic to the effects of ammonia. The importance of gut-derived products for HE is further supported by the efficacy of complete surgical exclusion (e.g., total colectomy) in the treatment of refractory HE (27).
Standard treatment options
Presently, lactulose and poorly absorbable antibiotics are the mainstay of treatment for HE. Lactulose is a non-absorbable, synthetic disaccharide that has multiple ef-fects on gut flora and, therefore, several potential mechanisms of action. Its most obvious effect is as a laxative; however, laxatives alone (e.g., water enemas) (28) are ineffective for HE. Additional putative mecha-nisms for the efficacy of lactulose may include:
1. Decreasing ammonia production by decreasing ure-ase activity and increasing assimilation of nitroge-nous products by bacteria;
2. Acidifying the colon contents resulting in a decrease in ammonia absorption into the gut; and
3. Decreasing toxic C4–C6 short chain fatty acid produc-tion by enhancing the producproduc-tion of non-toxic acetate (29).
Finally, lactulose may function as a prebiotic in the treatment of hepatic encephalopathy (30). A ‘prebiotic’ is defined as ‘a non-digestible food ingredient that
Fig. 1 Normal physiology. (A) Urease producing gut flora cleave urea in an enzymatic process resulting in net ammonia production. (B) Portal blood is then processed in the liver where most of it is cleared, allowing for normal brain function, (C).
beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improves host health’ (31). Specifically, lactulose significantly increases con-centrations of bifidobacteria and lactobacilli, and may have therapeutic effect through the mechanisms of these flora (32,33).
Non-absorbable antibiotics, principally neomycin and metronidazole, are also effective, presumably by killing gram negative and anaerobic urease producing bacteria. Further treatments can include dietary protein restric-tion (34), ornithine salts (35), and benzoate (36), al-though the latter are rarely used in practice.
While these treatments are effective, they impose side effects, toxicities, and cost. Lactulose has an unpleasant taste and causes flatulence and diarrhea. Due to unpre-dictable dose–responses, the diarrhea can be severe and result in hypertonic dehydration with hypernatremia with subsequent hyperosmolarity and altered mental status (37). Neomycin causes auditory loss, renal failure, diarrhea, and staphylococcal superinfection. Metroni-dazole neurotoxicity can be severe in cirrhotics (38). Antibiotics alter flora and result in bacterial resistance. Even dietary recommendations come with disadvan-tages; compliance is low, and an overly negative protein balance lead to loss of muscle mass and susceptibility to infections (39).
As a result of these concerns, clinicians and patients at times under-appreciate and under-treat HE, and often overlook minimal HE. Clearly, safe, well-tolerated, in-expensive alternatives are needed.
Rationale for probiotics
Probiotics may have multiple beneficial effects in the treatment of minimal HE. In principle, probiotics may
exhibit efficacy in the treatment of hepatic encephalop-athy by:
1. Decreasing total ammonia in the portal blood by: (a) decreasing bacterial urease activity,
(b) decreasing ammonia absorption by decreasing pH, (c) decreasing intestinal permeability,
(d) improving nutritional status of gut epithelium. 2. Decreasing inflammation and oxidative stress in the
hepatocyte leading to increased hepatic clearance of ammonia and other toxins.
3. Decreasing uptake of other toxins.
These processes may be additive or synergistic in treat-ing minimal HE.
First, by altering gut flora composition, selected via-ble, non-pathogenic bacteria can directly decrease am-monia production and absorption. This can be accomplished by changes in gut metabolism and pH, gut permeability, and the nutritional status of gut epithe-lium. As noted above, urease is a critical enzyme of bacterial lumenal metabolism that results in ammonia production and increased pH. Increased ammonia gen-eration and higher pH accelerate ammonia absorption into the portal blood; decreased pH result in decreased ammonia absorption. Probiotics may alter this process by competitive inhibition with urease-producing bacte-ria and increasing lumenal bactebacte-ria concentration. Ex-perimental evidence (presented below) have proven these mechanisms in humans. The exact mechanism by which probiotics have been shown to decrease fecal urease activity and pH are uncertain, but probiotics have been demonstrated to result in reduced concentrations of many bacteria (40), particulary gram negatives that produce urease. Further, probiotics improve human in-testinal permeability in experimental models (41). In addition, some have proposed that probiotics may
Fig. 2 Pathophysiology in cirrhosis. Intestinal dysmotility (A) exacerbates overgrowth of ureaseþbacterial (B) and increased absorption of nitrogenous products (C) into the portal blood. Shunting (D) and impaired hepatic processing (E) result in increased systemic exposure to an impaired blood–brain barrier (F) and astrocyte dysfunction (G) results.
enhance intestinal epithelial viability by providing es-sential nutritional support (e.g., medium chain fatty ac-ids) that inhibits apoptosis of lumenal epithelial cells (42). Thus, there are numerous possible mechanisms by which probiotics could decrease the absorption of am-monia into the portal blood.
Second, an extensive body of research has demon-strated that gut-derived inflammatory signaling ad-versely effects the hepatocyte itself, and that therapy directed against gut flora (e.g., probiotics) can limit or reverse this damage. These observations were first made
in rodent studies that identified a pathogenic role for intestinal bacteria in alcohol-induced liver disease. When ethanol-fed rats are given neomycin (to partially decontaminate the gut) polymyxin (43) (to bind lipop-olysacchride (LPS) and reduce its translocation from the intestinal lumen into the mesenteric blood) or lactoba-cillus (44) (to modify intestinal flora), they are protected from alcohol-induced liver damage. This protective ef-fect is the result of reduced hepatic exposure to intesti-nal products, such as LPS, that promote the release of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFa), from hepatic macrophages.
Similar mechanisms are now acknowledged to be important for the pathogenesis of both alcohol-related and non-alcohol related fatty liver disease (45,46), and a growing body of evidence suggests that the same mechanism may also contribute to liver damage caused by other hepatotoxins. Accordingly, there may be a common mechanism (namely, LPS-induced hepatotox-icity) that explains how diverse insults lead to liver damage (47). Such damage, in turn, disrupts normal hepatocyte function and leads to mitochrondial oxida-tive stress. Ultimately, the hepatocyte is impaired, and the clearance of toxins (including ammonia) is reduced. Treatment with probiotics may be ideal because they may protect against inflammation and hepatocyte dam-age from intestinal flora due to numerous mechanisms. As noted above, this has already been demonstrated in rodent models of alcohol liver disease. Recent work on a murine model of non-alcoholic fatty liver disease also supports this concept. These investigators found improvement in numerous molecular markers of
inflammation (i.e., NfK-B and TNFa) in the livers of mice that were fed oral probiotics (48).
Third, probiotics might inhibit the uptake of toxins other than ammonia that have not yet been identified. This notion is supported by research in patients with end stage renal disease on hemodialysis. These patients of-ten have altered mental status due in part to gut-derived toxins, such as phenol and indican, that not cleared by dialysis. Trials of lactic acid probiotics in humans with end stage renal disease to alter the gut flora and conse-quently reduce such toxins have demonstrated efficacy
(49,50). As noted above, some of the efficacy lactulose may indeed derive from its action as a ‘prebiotic’ en-couraging the growth of the same lactic acid bacteria used in probiotics. Probiotics are inexpensive, safe, and have no known negative long-term effects. This hy-pothesis is especially timely given that the expanding list of positive effects of probiotics are delineated by various laboratories (51,52). Further, probiotics are a natural therapy and, as such, are widely accepted by the public. Indeed, they are sometimes considered part of comple-mentary or alternative medicine (CAM). Studies consis-tently demonstrate extensive use of CAM by patients, including those with liver disease (53).
PRELIMINARY DATA
The study of hepatic encephalopathy has been greatly hindered by the lack of properly designed therapeutic trials (54). According to a recent consensus statement, criticisms that apply, to some degree, to all trials include ‘the large spectrum of clinical conditions summarized under the [term hepatic encephalopathy], the definition of study endpoints, the treatment of control groups, and the methods used to quantify therapeutic effects (55)’. Unfortunately, no useful animal models exist to study minimal hepatic encephalopathy. Accordingly, pre-liminary data must nevertheless come from relevant human trials and consideration of the relevant mecha-nisms of action.
All four published studies on the effect of probiotics on hepatic encephalopathy have demonstrated efficacy (56–59). These trials employed high doses of
non-Summary of putative mechanisms Alter flora,
+N4þproduction +
Intra-luminal pH,
+N4þabsorption
Alter short chain fatty acid production
+Intestinal permeability +Inflammatory signaling, mitochondrial-oxidative stress in hepatocyte +Absorption of other toxins Lactulose p p p Antibiotics p Probiotics p p p p p p
urease-producing bacteria, eitherLactobacillus acidoph-ilusorEnterococcus faeciumSF68. Because these studies did not employhighly concentrated, viable bacteria, they required frequent dosing and/or ingestion of a large quantity of fluid (up to a liter). Further, the mechanisms of action of these probiotic strains in liver disease or hepatic encephalopathy are uncertain, and have not been thoroughly studied with this interest in mind. Fi-nally, these studies were small, lacked a placebo con-trolled design and firm, well-established endpoints. Nevertheless, their success demonstrates a certain ‘proof of principle’ that warrants further attention.
One possible probiotic compound that might be ide-ally suited to HE is the highly concentrated combination probiotic, VSL#3.This product contains 51011cfu/g of
viable, lyophilized bifidobacteria (Bifidobacterium lon-gum, Bifidobacterium infantis, and Bifidobacterium breve), lactobacilli (L. acidophilus, Lactobacillus casei,
Lactobacillus delbrueckiisubsp.Lactobacillus bulgaricus, andLactobacillus plantarium) and a mixture of Strepto-coccus thermophilusstrains. Viability has been proven by stool collection (60). Potential advantage for its applica-tion to HE include:
1. VSL#3 has been shown to reduce stool urease activity in humans.
2. VSL#3 has been shown to reduce stool pH in humans. 3. VSL#3 alters production of short chain fatty acids in
humans.
4. VSL#3 improves intestinal permeability and decrease inflammatory signals in murine and human colonic cell culture models.
First, VSL#3 has been proven to reduce stool urease ac-tivity. In a clinical trial (61), 10 patients with irritable bowel syndrome or functional diarrhea were given VSL#3, and urease activity was measured at study entry, 20 days after VSL#3 administration, and 10 days after discontinuation. The investigators found a greater than 50% reduction during VSL#3 administration, and a subsequent return toward baseline levels upon discon-tinuation.
Second, VSL#3 is proven to reduce stool pH (60). Stool specimens were studied in 20 patients with ulcerative colitis who were intolerant of or allergic to 5-aminosali-cylic acid in order to determine the impact on fecal com-position by VSl#3. Stool comcom-position of component bacteria all increased significantly. Of particular interest is that the stool pH dropped significantly (p<0:005) and remained stable throughout the treatment. Since uptake of nitrogenous compounds is favored by a higher pH and diminished by a lower pH, this effect could have a major impact on ammonia generation in patients with cirrhosis. Further, VSL#3 may reduce short chain fatty acids, including butyrate in particular. In vitro culture of
human ileostomy effluent inoculated with VSL#3 dem-onstrated a decrease in short chain fatty acids and bu-tyrate compared to control (62). VSL#3 also improves intestinal permeability and decreases inflammatory sig-naling in murine colitis models (the interleukin-10 knockout mouse) and human colonic cell cultures (T84 monolayers) (63). Oral VSL#3 for four weeks lead to de-creases in mucosal secretion of the pro-inflammatory cytokines TNFa and interferon c and increased resis-tance to samonella invasion.
Finally, as noted previously, an attribute shared by all probiotics is their intrinsic safety and tolerability. CONCLUSIONS
Hepatic encephalopathy is a serious and common com-plication of liver disease. While the exact pathogenesis remains uncertain, nitrogenous products of gut flora metabolism certainly play a critical role. Present treat-ment strategies, including lactulose and poorly absorb-able antibiotics, may not be optimal therapy for all patients with liver disease due to side-effects and cost. Compliance with therapy, particularly for minimal HE, is often low.
Probiotics have multiple mechanisms of action that may make them superior to conventional therapy. Since probiotics are a safe, natural, well-tolerated therapy ap-propriate for long-term use, probiotic therapy for HE may be ideal. Amongst presently available probiotic products, VSL#3 may be best suited for this purpose. This hypothesis should be tested in rigorously designed clinical trials.
ACKNOWLEDGEMENT
The author would like to acknowledge Anna Mae Diehl, MD, for advice and support.
REFERENCES
1. Blei A., Cordoba J. Hepatic encephalopathy.Am J Gastroenterol2001;96(7): 1968–1976.
2. Gilberstadt S. J., Gilberstadt H., Zieve L., Buegel B., Collier R. O., Jr, McClain C. J. Psychomotor performance defects in cirrhotic patients without overt encephalopathy.Arch Intern Med1980;140: 519–521.
3. Gitlin N., Lewis D. C., Hinkley L. The diagnosis and prevelance of subclinical hepatic encephalopthy in apparently healthy, ambulant, non-shunted patients with cirrhosis.J Hepatol1986;3: 75–82.
4. Weissenborn K., Ennen J. C., Schomerus H., Ruckery N., Hecker H. Neuropsychological characterization of hepatic encephalopathy.J Hepatol2001;34: 768–773.
5. Schomerus H., Hamster W., Blunck H., Reinhard U., Mayer K., Dolle W. Latent portosystemic encephalopathy. I. Nature of cerebral functional defects and their effect on fitness to drive.Dig Dis Sci1981;26: 622–630.
6. Hamster, W. Neuropsychologie der latenten
portosystemischen Enzephalopathie. Hebilitationsschrift, Medizinische Fakultat der Eberhard-Karls-Universistat Turbingen, Turbingen, 1982.
7. Groenweg M., Qeuro J. C., De Bruijn I. et al. Subclinical hepatic encephalopathy impairs daily functioning.
Hepatology1998;28: 45–49.
8. Conn H. O. Quantifying the severity of hepatic encephalopathy. In: H. O. Conn, Bircher (eds).Hepatic Encephalopathy: Syndromes and Therapies. East Lansing, MI: Medi-Ed Press, 1993: 13–26.
9. Burne R., Chen Y. Bacterial ureases in infectious diseases.
Microb Infect2000: 533–542.
10. Nomura F., Ohnishik K., Terabayshi H. et al. Effect of intrahepatic portal-systemic shunting on hepatic ammonia extraction in patients with cirrohsis.Hepatology1994;20: 1478–1481.
11. Schmidt-Nielsen K.Animal Physiology, 4th Edn. Cambridge: Cambridge University Press, 1994. p. 387.
12. Collins C. M., D’Orazio S. E. Bacterial ureases: structure, regulation of expression and role in pathogenesis.Mol Microbiol1993;9(5): 907–913.
13. Mobley H. L., Hausinger R. P. Molecular biology of microbial ureaes.Microbiol Rev1995;59(3): 451–480. 14. Thompson A., Visek W. J. Some effects of induction of
urease immunity in patients with hepatic insufficiency.Am J Med1963;35: 804–809.
15. LeVeen H. H., LeVeen E. G., LeVeen R. F. Awakenings to the pathogenicity of urease and the requirement for continuous long term therapy.Biomed Pharmacother1994;48: 157–166. 16. Nielsen A. E.Kemiske Data. Kobenhavn: F.A.D.L’s Forlag,
1976.
17. Clausen M. R. Production and oxidation of short-chain fatty acids in the human colon.Danish Med Bull1998;45(1): 51– 75.
18. Mortensen P. B., Holtug K., Bonnen H., Clausen M. R. The degradation of amino acids, proteins, and blood to short-chain fatty acids in the colon is prevented by lactulose.
Gastroenterology1990;98: 353–360.
19. Dheeraj L., Gorbach S., Levitan R. Intestinal microflora in patients with alcholic cirrhosis: urea-splitting bacteria and neomycin resistance.Gastroenterology1972;(62): 275–279. 20. Hansen B. A., Vilstrup H. Increased intestinal hydrolysis of
urea in patients with alcoholic cirrohsis.Scand J Gastroenterol1985;(20): 346–350.
21. Yang C. Y., Chang C. S., Chen G. H. Small-intestinal bacterial overgrowth in patients with liver cirrohsis, diagnosed with glucose H2 or CH4 breath tests.Scand J Gastroenterol1998;33(8): 867–871.
22. Lockwood A. H., Yap E. W., Wong W. H. Cerebral ammonia metabolism in patients with severe liver disease and minimal hepatic encephalopathy.J Cereb Blood Flow Metab
1991;11: 337–341.
23. Haussinger D., Kircheis G., Fischer R., Schliess F., vom Dahl S. Hepatic encephalopathy in chronic liver disease: a clinical manifestation of astrocyte swelling and low grade cerebra edema?J Hepatol2000;32: 1035–1038.
24. Blei A.Bailliere’s Clin Gastroenterol2000;14(6): 959–974. 25. Yurdaydin C., Walsh T. J., Engler H. D. et al. Gut bacteria provide precursors of benzodiazepine receptor ligands in a rat model of hepatic encephalopathy.Brain Res1995;679: 42–48.
26. Zieve L., Doizaki W. M., Zieve J. Synergism between mercaptans and ammonia or fatty acids in the production of
coma: a possible role for mercaptans in the pathogenesis of hepatic coma.J Lab Clin Med1974;83: 16–28.
27. Dagenais M. H., Bernard D., Marleau D. et al. Surgical treatment of severe postshunt hepatic encephalopathy.
World Surg1991;15: 109–114.
28. Uribe M., Campollo O., Vargas F. Acidifying enemas (lacitiol and lactose) vs. nonacidifying enemas (tap water) to treat acute portal-systemic encephalopathy: a double-blind, randomized clinical trial.Hepatology1987;7: 639–643. 29. Clausen M. R., Mortensen P. B. Lactulose, disaccharides and
colonic flora.Drugs1997;53(6): 930–942.
30. Jenkins D., Kendall C. W., Vuksan V. Inulin, oligofructose, and intestinal function.J Nutr1999;129: 1431S–1433S. 31. Gibson G. R., Roberfroid M. B. Dietary modification of the
human colonic microbiota-introducing the concept of prebiotic.Nutrition1995;125: 1401–1412.
32. Rycroft C. E., Jones M. R., Gibson G. R., Rastall R. A. A comparative in vitro evaluation of the fermentation properties of prebiotic oligosaccharides.J Appl Microbiol
2001;(91): 878–887.
33. Salminen S., Salminen E. Lactuluose, lactic acid bacteria, intestinal microecology and mucosal protection.Scand Gastroenterol1997;222: 45–48.
34. Uribe M., Conn H. O. Dietary management of portal-systemic encephalopathy. In: H. O. Conn, A. Bircher (eds).
Hepatic Encephalopathy: Syndromes and Therapies. Bloomington, IL: Medi-Ed Press, 1994: 331–349.
35. Herlong H. F., Maddrey W. C., Walser M. The use of ornithine salts of branched-chain ketocids in portal-systemic
encephalopathy.Ann Intern Med1980;93: 545–550. 36. Sushma S., Dasarathy S., Tandon R. K., Jain S., Gupta S.,
Bhist M. S. Sodium benzoate in the treatment of acute hepatic encephalopathy: a double-blind randomized trial.
Hepatology1992;16: 138–144.
37. Warren S. E., Mitas J. A., Swerdlin A. H. Hypernatremia in hepatic failure.JAMA1980;243: 1257–1260.
38. Lost S., Sonne J., Dossing M., Andreasen P. B. Metronidazole pharmokinetics in patients with hepatic encephalopathy.
Scand J Gastroenterol1987;22: 117–123.
39. Gerber T., Schomerus H. Hepatic encephalopathy in liver cirrhosis.Drugs2000;60(6): 1353–1370.
40. Gibson G. R., Wang X. Regulatory effects of bifidobacteria on the growth of other colonic bacteria.Appl Bacteriol1994; 77(4): 412–420.
41. Madsen K. L., Cornish A., Soper P. Probiotic bacteria enhance murine and human intestinal epithelial barrier function.Gastroenterology2001;121: 580–591. 42. Kanauchi O., Fujiyama Y., Mitsuyama K. et al. Incresed
growth of bifidobacterium and eubacterium by germinated barely foodstuff, accompanied by enhanced butyrate production in healthy volunteers.Int J Mol Med1999;3(2): 175–179.
43. Adachi Y., Moore L. E., Bradford B. U., Gao W., Thurman R. G. Antibiotics prevent liver injury in rats following long-term exposure to ethanol.Gastroenterology1995;108(1): 218–224.
44. Nanj A. A., Khettry U., Sadrzadeh S. M. H. Lactobacillus feeding reduces endotoxemia and severity of experimental alcoholic liver disease.Proc Soc Exp Biol Med1994;205: 243–247.
45. Yang S. Q., Lin H. Z., Lane M. D., Clemens M., Diehl A. M. Obesity increases sensitivity to endotoxin liver injury: implications for the pathogenesis of steatohepatitis.PNAS
46. Enomoto N., Ikejima K., Bradford B. U. et al. Hepatology: microcirculation and pathogenesis of alcoholic liver injury. Role of Kupffer cells and gut-derived endotoxins in alcoholic liver injury.J Gastroenterol Hepatol2000; 15(suppl): D20–D25.
47. Yang S. Q., Lin H., Diehl A. M. Fatty liver vulnerability to endotoxin-induced damage despite NF-kappaB induction and inhibited caspase 3 activation.Am J Physiol Gastrointest Liver Physiol2001;281(2): G382–G392.
48. Li Z., Yang S. Q., Lin H. Z. et al. Probiotics and anti-TNF antibodies inhibit inflammatory activity and improve non-alcoholic fatty liver disease in ob/ob mice. Abstract DDW 2002, in review.
49. Hida M., Aiba Y., Sawamura S. et al. Inhibition of the accumulation of uremic toxins in the blood and their precursors in the feces after oral administration of Lebenin, a lactic acid bacteria preparation, to uremic patients undergoing hemodialysis.Nephron1996;74: 349–355. 50. Simenhoff M. L., Dunn S. R., Zollner G. P. et al.
Biomodulation of the toxic and nutritional effects of small bowel bacterial overgrowth in end-stage kidney disease using freeze-driedLactobacillus acidophilus.Miner Electrolyte Metab1996;22(1–3): 92–96.
51. Rolfe R. D. The role of probiotic cultures in the control of gastrointestinal health.J Nutr2000;130(2s suppl): 396s– 402s.
52. Gionchetti P., Rizzello F., Venturi A., Campieri M. Probiotics in infective diarrhea and inflammatory bowel diseases.J Gastroenterol Hepatol2000;15: 489–493.
53. Seeff L., Lindsay K. L., Bacon B. R., Kresina T. F., Hoofnagle J. H. Complementary and alternative medicine in chronic liver disease.Hepatology2001;34(3): 595–603.
54. Ferenci P. Hepatic encephalopathy; treatment. In: J. W. D. McDonald, A. K. Burroughs, B. G. Feagan (eds).Evidence Based Gastroenterology and Hepatology. London: British Medical Journal-Books, 1999: 443–455.
55. Ferenci P., Lockwood A., Mullen K., Tarter R., Weissenborn K., Blei A. Hepatic encephalopathy-definition,
nomenclature, diagnosis, and quantification. Final Report of the Working Party at the 11th World Congress of
Gastroenterology, Vienna, 1998.Hepatololgy2002; 35: 716–721.
56. Macbeth W., Kass E., McDermott W. Treatment of hepatic encephalopathy by alteration of intestinal flora
withLactobacillus acidophilus.Lancet1965;1: 399–403.
57. Read A. E., McCarthy C. F., Heaton K. W., Laidlaw J.
Lactobacillus acidophilus(Enpac) in treatment of hepatic encephalopathy.BMJ1966;1: 1267–1269.
58. Loguerico C., Abbiati R., Rinaldi M., Romano A., Del Vecchio Blanco C., Coltori M. Long-term effects of Enterococcus faecium SF68 versus lactulose in the treatment of patients with cirrhosis and grade 1–2 hepatic encephalopathy.J Hepatol1995;23: 39–46.
59. Loguercio C., Del Vecchio Blanco C., Coltorti M.
Enterococcus lactic acid bacteria strain SF68 and lactulose in hepatic encephalopathy: a controlled study.J Int Med Res
1987;15(6): 335–343.
60. Venturi A., Gionchetti P., Rizzello F. et al. Impact on the composition of the faecal flora by a new probiotic preparation: preliminary data on maintenance treatment of patients with ulcerative colitis.Aliment Pharmacol Ther
1999;13: 1103–1108.
61. Brigidi P., Vitali B., Swennen E., Bazzocchi G., Matteuzzi D. Effects of probiotic administration upon the composition and enzymatic activity of human fecal microbiota in patients with irritable bowel syndrome or functional diarrhea.Res Microbiol2001;152: 735–741. 62. Bianchi-Salvadori B., Vesely R., Ferrari A., Canzi E.,
Casiraghi C., Brighenti F. Behaviour of the pharmaceutical probiotic preparation VSL#3 in human ileostomy effluent containing its own natural elements.New Microbiol2001; 24(1): 23–33.
63. Madsen K. L., Cornish A., Soper P et al. Probiotic bacteria enhance murine and human intestinal epithelial barrier function.Gastroenterology2001;121: 580–591.
