Frederick Suchy - Academia.edu (original) (raw)
Papers by Frederick Suchy
Journal of the American Academy of Dermatology, 1986
Pyoderma gangrenosum is a cutaneous disorder associated with systemic diseases such as ulcerative... more Pyoderma gangrenosum is a cutaneous disorder associated with systemic diseases such as ulcerative colitis, Crohn's disease, rheumatoid arthritis, and blood dyscrasias. We are reporting two cases of pustular pyoderma gangrenosum associated with ulcerative colitis. One patient had inactive bowel disease when she developed her third episode of pustules, erosions, and nodules on the left leg. The other patient exhibited a widespread painful vesiculopustular eruption that coincided with the onset of her colitis. Both patients presented with pustules as the primary manifestation of their pyoderma gangrenosum. Histologic examination of skin from both patients revealed an acute perifollicular inflammation. Pyoderma gangrenosum should be considered in the differential diagnosis of pustular disorders in children with underlying conditions such as ulcerative colitis. (J AM ACAD DERMATOL 15:608-614, 1986.)
The FASEB Journal
Transport of bile acids across the canalicular membrane of the hepatocyte provides the primary mo... more Transport of bile acids across the canalicular membrane of the hepatocyte provides the primary motive force for generation of bile flow and is rate limiting in the vectorial movement of bile acids from blood to bile. Several distinct carriers for bile acids have been defined based on physiological studies in isolated hepatocytes, membrane vesicles, hepatocyte couples, and the perfused rat liver including membrane potential-driven and ATP-dependent mechanisms. Several groups have isolated and functionally reconstituted a canalicular bile acid transport protein of M(r) approximately 110 kDa. The ATP-dependent mechanism for secretion of monovalent bile acids appears to be mediated by a yet to be identified protein of the ATP binding cassette family of transporters. However, it remains conjectural whether the ATP-dependent and membrane potential-driven components of canalicular bile acid transport are mediated by one or more transport proteins. Bile acid sulfates and glucuronides are substrates for the canalicular multispecific organic anion transporter whose activity has recently been associated with the multidrug resistance-associated protein.
The American journal of physiology
Adenosine 3',5'-cyclic monophosphate (cAMP), acting via protein kinase A, increas... more Adenosine 3',5'-cyclic monophosphate (cAMP), acting via protein kinase A, increases transport maximum of Na+-taurocholate cotransport within 15 min in hepatocytes (S. Grüne, L. R. Engelking, and M. S. Anwer. J. Biol. Chem. 268: 17734-17741, 1993); the mechanism of this short-term stimulation was investigated. Cycloheximide inhibited neither basal nor cAMP-induced increases in taurocholate uptake in rat hepatocytes, indicating that cAMP does not stimulate transporter synthesis. Studies in plasma membrane vesicles showed that taurocholate uptake was not stimulated by the catalytic subunit of protein kinase A but was higher when hepatocytes were pretreated with cAMP. Immunoblot studies with anti-fusion protein antibodies to the cloned Na+-taurocholate cotransport polypeptide (Ntcp) showed that pretreatment of hepatocytes with cAMP increased Ntcp content in plasma membranes but not in homogenates. Ntcp was detected in microsomes, endosomes, and Golgi fractions, and cAMP pretreatment resulted in a decrease only in endosomal Ntcp content. It is proposed that cAMP increases transport maximum of Na+-taurocholate cotransport, at least in part, by translocating Ntcp from endosomes to plasma membranes.
The American journal of physiology
The rat ileal apical Na+-dependent bile acid transporter (ASBT) and the liver Na+-taurocholate co... more The rat ileal apical Na+-dependent bile acid transporter (ASBT) and the liver Na+-taurocholate cotransporting polypeptide (Ntcp) are members of a new family of anion transporters. These transport proteins share limited sequence homology and almost identical predicted secondary structures but are localized to the apical surface of ileal enterocytes and the sinusoidal surface of hepatocytes, respectively. Stably transfected Madin-Darby canine kidney (MDCK) cells appropriately localized wild-type ASBT and Ntcp apically and basolaterally as assessed by functional activity and immunocytochemical localization studies. Truncated and chimeric transporters were used to determine the functional importance of the cytoplasmic tail in bile acid transport activity and membrane localization. Two cDNAs were created encoding a truncated transporter in which the 56-amino-acid COOH-terminal tail of Ntcp was removed or substituted with an eight-amino-acid epitope FLAG. For both mutants there was some loss of fidelity in basolateral sorting in that approximately 75% of each protein was delivered to the basolateral surface compared with approximately 90% of the wild-type Ntcp protein. In contrast, deletion of the cytoplasmic tail of ASBT led to complete loss of transport activity and sorting to the apical membrane. An Ntcp chimera in which the 56-amino-acid COOH-terminal tail of Ntcp was replaced with the 40-amino-acid cytoplasmic tail of ASBT was largely redirected (82.4 +/- 3.9%) to the apical domain of stably transfected MDCK cells, based on polarity of bile acid transport activity and localization by confocal immunofluorescence microscopy. These results indicate that a predominant signal for sorting of the Ntcp protein to the basolateral domain is located in a region outside of the cytoplasmic tail. These studies have further shown that a novel apical sorting signal is localized to the cytoplasmic tail of ASBT and that it is transferable and capable of redirecting a protein normally sorted to the basolateral surface to the apical domain of MDCK cells.
Gastroenterology
Malabsorption and deficiency of vitamin E causing neurological degeneration are common consequenc... more Malabsorption and deficiency of vitamin E causing neurological degeneration are common consequences of chronic childhood cholestatic liver disease. The objective of this study was to determine the long-term efficacy and safety of d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) in correcting vitamin E deficiency in children with chronic cholestasis who were unresponsive to other forms of oral vitamin E. Sixty vitamin E-deficient children with chronic cholestasis unresponsive to 70-212 IU.kg-1.day-1 of oral vitamin E were entered into a trial at eight centers in the United States. After initial evaluation, treatment was started with 25 IU.kg-1.day-1 of TPGS. Vitamin E status, neurological function quantitated by a specific scoring system, and clinical and biochemical parameters were monitored during therapy. All children responded to TPGS with normalization of vitamin E status. Neurological function, which had deteriorated before entry in the trial, improved in 25 patient...
Bile acids, which are present at physiological pH val- ues as bile salts, are synthesized in the ... more Bile acids, which are present at physiological pH val- ues as bile salts, are synthesized in the hepatocyte from cholesterol and secreted across the canalicular (apical) membrane into bile. Bile salts are taken up from blood across the sinusoidal (basal) membrane, in part metabolized within the hepatocyte, and se- creted into bile. The uphill bile salt transport across the canalicular
The Israel Medical Association journal : IMAJ, 2011
Primary liver masses in children may require intervention because of symptoms or concern about ma... more Primary liver masses in children may require intervention because of symptoms or concern about malignant transformation. To review the management and outcome of benign liver masses in children. We conducted a retrospective chart review of children with liver masses referred to our institution during the period 1997-2009. Benign liver masses were identified in 53 children. Sixteen of these children (30%) had hemangioma/infantile hepatic hemangioendothelioma (IHH) and 15 (28%) had focal nodular hyperplasia. The remainder had 6 cysts, 4 hamartomas, 3 nodular regenerative hyperplasia, 2 adenomas, 2 vascular malformations, and one each of polyarteritis nodosa, granuloma, hepatic hematoma, lymphangioma, and infarction. Median age at presentation was 6 years, and 30 (57%) were female. Masses were initially noticed on imaging studies performed for unrelated symptoms in 33 children (62%), laboratory abnormalities consistent with liver disease in 11 (21%), and palpable abdominal masses in 9 (...
Journal of lipid research, 2003
We investigated how cholesterol feeding regulates cholesterol 7alpha-hydroxylase (CYP7A1) via the... more We investigated how cholesterol feeding regulates cholesterol 7alpha-hydroxylase (CYP7A1) via the nuclear receptors farnesoid X receptor (FXR) and liver X receptor alpha (LXRalpha) in New Zealand white rabbits. After 1 day of 2% cholesterol feeding, when the bile acid pool size had not expanded, mRNA levels of the FXR target genes short-heterodimer partner (SHP) and sterol 12alpha-hydroxylase (CYP8B) were unchanged, indicating that FXR activation remained constant. In contrast, the mRNA levels of the LXRalpha target genes ATP binding cassette transporter A1 (ABCA1) and cholesteryl ester transfer protein (CETP) increased 5-fold and 2.3-fold, respectively, associated with significant increases in hepatic concentrations of oxysterols. Activity and mRNA levels of CYP7A1 increased 2.4 times and 2.2 times, respectively. After 10 days of cholesterol feeding, the bile acid pool size increased nearly 2-fold. SHP mRNA levels increased 4.1-fold while CYP8B declined 64%. ABCA1 mRNA rose 8-fold ...
Journal of lipid research, 2001
To study the effect of cholecystectomy on the regulation of classic and alternative bile acid syn... more To study the effect of cholecystectomy on the regulation of classic and alternative bile acid syntheses, gallbladder-intact (n = 20) and cholecystectomized (n = 20) New Zealand White rabbits were fed either chow or chow with 2% cholesterol (3 g/day). After 10 days, bile fistulas were constructed in half of each rabbit group to recover and measure the bile acid pool and biliary bile acid flux. After cholesterol feeding, the bile acid pool size increased from 268 +/- 55 to 444 +/- 77 mg (P < 0.01) with a 2-fold rise in the biliary bile acid flux in intact rabbits but did not expand the bile acid pool (270 +/- 77 vs. 276 +/- 62 mg), nor did the biliary bile acid flux increase in cholecystectomized rabbits. Ileal apical sodium-dependent bile acid transporter protein increased 46% from 93 +/- 6 to 136 +/- 23 units/mg (P < 0.01) in the intact rabbits but did not change in cholecystectomized rabbits (104 +/- 14 vs. 99 +/- 19 units/mg) after cholesterol feeding. Cholesterol 7alpha-hyd...
Journal of lipid research, 1984
Development of the capacity for hepatic biotransformation of potentially toxic, endogenous compou... more Development of the capacity for hepatic biotransformation of potentially toxic, endogenous compounds such as lithocholate may be dependent on induction by substrate or hormonal modulation. Our aim was to observe the ontogeny of hepatic sulfotransferase (ST) activity, a presumed detoxification pathway, and to determine the effect of substrate ingestion and cortisone administration on ST activity. Pregnant rats were fed a standard chow diet containing lithocholate; the maternal diet was continued during the suckling and weaning phase of the pups. Liver cytosol and serum were obtained from dams and from pups at weekly intervals from fetal life through 4 weeks of age. In controls, there was a progressive increase in hepatic ST activity from 6.2 +/- 2.9 pmol/mg protein per min, (mean +/- SEM) in fetal liver, 18.1 +/- 3.9 at 1 week, an 33.6 +/- 7.2 at 2 weeks to a peak of 56.4 +/- 11.8 at 3 weeks of age. In female rats older than 4 weeks of age, ST activity in hepatic cytosol was threefol...
Gut, 2004
Background: Obese Zucker rats (ZR) have been used as an experimental model for non-alcoholic fatt... more Background: Obese Zucker rats (ZR) have been used as an experimental model for non-alcoholic fatty liver disease and are particularly susceptible to various types of liver injury. Bile secretory function has not been assessed in ZR.Aim: To study bile secretion and expression of the main hepatobiliary transporters in ZR.Methods: Bile flow and biliary secretion of lipids and glutathione were determined
International journal of biochemistry and molecular biology, 2012
The human organic solute transporter (hOST) is a heterodimer composed of alpha and beta subunits.... more The human organic solute transporter (hOST) is a heterodimer composed of alpha and beta subunits. Physical association of hOSTα and β subunits is essential for their polarized basolateral plasma membrane localization and function in the export of bile acids and steroids. To understand the role of carboxyl- and amino-tails of OSTβ and mechanisms underlying membrane localization of hOST, the effects of tail deletion of the hOSTβ subunit and biological reagents on membrane distribution and transport function of hOST were investigated in stably transfected MDCK cells. After deletion of 35 amino acids from the amino-tail of hOSTβ, the efflux transport activity and polarized membrane distribution of the truncated hOSTβ was abolished. A co-immunoprecipitation study verified that the amino-tail of hOSTβ is essential for the association with hOSTα subunit. Treatments with acytochalasin D (interrupting ctin-filaments), bafilomycin A1 (inhibiting vacuolar H(+)-ATPase), brefeldin A (disrupting ...
Human molecular genetics, Jan 28, 2015
The control of transcription is regulated through the well-coordinated spatial and temporal inter... more The control of transcription is regulated through the well-coordinated spatial and temporal interactions between distal genomic regulatory elements required for specialized cell-type and developmental gene expression programs. With recent findings CFTR has served as a model to understand the principles that govern genome-wide and topological organization of distal intra-chromosomal contacts as it relates to transcriptional control. This is due to the extensive characterization of the DNase hypersensitivity sites, modification of chromatin, transcription factor binding sites and the arrangement of these sites in CFTR consistent with the restrictive expression in epithelial cell types. Here, we identified CHD6 from a screen among several chromatin-remodeling proteins as a putative epigenetic modulator of CFTR expression. Moreover, our findings of CTCF interactions with CHD6 are consistent with the role described previously for CTCF in CFTR regulation. Our results now reveal that the C...
Fibrocystic Diseases of the Liver, 2010
The cystic diseases of the liver are mostly autosomal recessive disorders with variable intrahepa... more The cystic diseases of the liver are mostly autosomal recessive disorders with variable intrahepatic biliary dilatation and increased hepatic fibrosis either as part of the underlying defect or as a result of liver damage from recurrent episodes of ascending cholangitis. Caroli disease (CD) denotes congenital saccular intrahepatic dilatation of the biliary tree. Caroli syndrome (CS) is a more common disorder
Clinics in Liver Disease, 2006
The hepatic fibrocystic diseases present with variable intrahepatic biliary abnormalities, which ... more The hepatic fibrocystic diseases present with variable intrahepatic biliary abnormalities, which range from portal tract enlargement and fibrosis to cystic formations. They may present as autosomal recessive or dominant polycystic kidney diseases, with associated dilatation of the renal collecting system, or as incompletely characterized cystic diseases. Symptoms from the liver disease often result from complications of fibrosis or dilated ducts/cyst (sludge, lithiasis, infection). The treatment is supportive, with careful attention to associated renal disease. Liver transplantation is an option in selected patients.
Journal of lipid research, 2002
We investigated the role of the orphan nuclear receptor farnesoid X receptor (FXR) in the regulat... more We investigated the role of the orphan nuclear receptor farnesoid X receptor (FXR) in the regulation of cholesterol 7alpha-hydroxylase (CYP7A1), using an in vivo rabbit model, in which the bile acid pool, which includes high affinity ligands for FXR, was eliminated. After 7 days of bile drainage, the enterohepatic bile acid pool, in both New Zealand White and Watanabe heritable hyperlipidemic rabbits, was depleted. CYP7A1 activity and mRNA levels increased while FXR was deactivated as indicated by reduced FXR protein and changes in the expression of target genes that served as surrogate markers of FXR activation in the liver and ileum, respectively. Hepatic bile salt export pump mRNA levels and ileal bile acid-binding protein decreased while sterol 12alpha-hydroxylase and sodium/taurocholate cotransporting polypeptide mRNA levels increased in the liver. In addition, hepatic FXR mRNA levels decreased significantly. The data, taken together, indicate that FXR was deactivated when the ...
Seminars in Liver Disease, 2011
Progressive familial intrahepatic cholestatic diseases encompass a group of autosomal recessive h... more Progressive familial intrahepatic cholestatic diseases encompass a group of autosomal recessive hereditary diseases, which usually present in infancy or childhood, with cholestasis of hepatocellular origin. The currently preferred nomenclature for the three PFIC disorders that have been characterized to date is FIC1 deficiency, BSEP deficiency, and MDR3 deficiency, relating to mutations in the specific genes involved in bile acid formation and transport. Since the first description of these diseases, extensive clinical, biochemical, and molecular studies have increased our understanding of the features specific to each one of them. This review focuses mainly on the liver histology, summarizing their characteristic pathologic features, the correlation to specific genotypes, and complications arising with disease progression.
Pharmaceutical Research, 2008
The human organic anion transporting polypeptide C (OATPC) is one of the major transport proteins... more The human organic anion transporting polypeptide C (OATPC) is one of the major transport proteins involved in the enterohepatic circulation of bile salts and plays an important role in vectorial transport of organic anions and drugs across hepatocytes. In this study, the effects of biological reagents on the membrane localization of OATPC were investigated by confocal microscopy and estrone-3-sulfate transport. Our results demonstrated that the functional membrane expression of fluorescent chimera OATPC-GFP was achieved in non-polarized (COS7 and HEK293) and polarized (MDCK) cells. Both brefeldin A (a Golgi complex disruptor) and bafilomycin A1 (an inhibitor of vacuolar H+-ATPase) treatment significantly decreased the polarized membrane trafficking and markedly reduced the uptake of estrone-3-sulfate ( approximately 40-90%) in OATPC-GFP transfected cells, suggesting that membrane sorting of hOATPC-GFP was mediated by Golgi complex and vacuolar H+-ATPase-related vesicle transport pathways. Treatment with 8-Br-cAMP (a cAMP analog) stimulated OATPC-GFP membrane localization and enhanced estrone-3-sulfate uptake by approximately 20%. The protein kinase A (PKA) inhibitors (H89 and KT5720), but not a PKG inhibitor, blocked the polarized membrane expression of OATPC-GFP and reduced estrone-3-sulfate transport activity. The simultaneous treatment of cells with PKA activator/inhibitor and bafilomycin A1 demonstrated that bafilomycin A1 did not change the effects of 8-Br-cAMP and H89 on the membrane localization of OATPC-GFP compared with the use of 8-Br-cAMP and H89 alone. These data suggest that a cAMP-PKA sensitive membrane sorting pathway for OATPC-GFP is independent of the vacuolar H+-ATPase associated (bafilomycin A1 sensitive) vesicle mediated membrane sorting pathway. In contrast, with combined treatment with brefeldin A, neither the PKA-activator (8-Br-cAMP) nor the inhibitor (H89) further altered the plasma membrane expression and transport activity of OATPC-GFP compared with brefeldin A treatment alone. These data suggest that the cAMP-PKA regulation of OATPC membrane expression involves the Golgi complex. When the Golgi apparatus was disrupted by brefeldin A treatment, the effects of cAMP-PKA on the Golgi-to-basolateral surface sorting process of OATPC was also diminished. In summary, the plasma membrane localization of human OATPC is mediated by Golgi complex and vacuolar H+-ATPase vesicle mediated membrane sorting pathways. cAMP-PKA regulates sorting process through the Golgi complex but not the vacuolar H+-ATPase associated vesicular pathway.
PEDIATRICS, 2009
WHAT'S KNOWN ON THIS SUBJECT: Nonadherence increases morbidity and mortality rates in the posttra... more WHAT'S KNOWN ON THIS SUBJECT: Nonadherence increases morbidity and mortality rates in the posttransplant setting. Adolescents are more prone to nonadherence. TM has been used with efficacy for a variety of chronic diseases, such as diabetes mellitus and asthma.
Journal of the American Academy of Dermatology, 1986
Pyoderma gangrenosum is a cutaneous disorder associated with systemic diseases such as ulcerative... more Pyoderma gangrenosum is a cutaneous disorder associated with systemic diseases such as ulcerative colitis, Crohn's disease, rheumatoid arthritis, and blood dyscrasias. We are reporting two cases of pustular pyoderma gangrenosum associated with ulcerative colitis. One patient had inactive bowel disease when she developed her third episode of pustules, erosions, and nodules on the left leg. The other patient exhibited a widespread painful vesiculopustular eruption that coincided with the onset of her colitis. Both patients presented with pustules as the primary manifestation of their pyoderma gangrenosum. Histologic examination of skin from both patients revealed an acute perifollicular inflammation. Pyoderma gangrenosum should be considered in the differential diagnosis of pustular disorders in children with underlying conditions such as ulcerative colitis. (J AM ACAD DERMATOL 15:608-614, 1986.)
The FASEB Journal
Transport of bile acids across the canalicular membrane of the hepatocyte provides the primary mo... more Transport of bile acids across the canalicular membrane of the hepatocyte provides the primary motive force for generation of bile flow and is rate limiting in the vectorial movement of bile acids from blood to bile. Several distinct carriers for bile acids have been defined based on physiological studies in isolated hepatocytes, membrane vesicles, hepatocyte couples, and the perfused rat liver including membrane potential-driven and ATP-dependent mechanisms. Several groups have isolated and functionally reconstituted a canalicular bile acid transport protein of M(r) approximately 110 kDa. The ATP-dependent mechanism for secretion of monovalent bile acids appears to be mediated by a yet to be identified protein of the ATP binding cassette family of transporters. However, it remains conjectural whether the ATP-dependent and membrane potential-driven components of canalicular bile acid transport are mediated by one or more transport proteins. Bile acid sulfates and glucuronides are substrates for the canalicular multispecific organic anion transporter whose activity has recently been associated with the multidrug resistance-associated protein.
The American journal of physiology
Adenosine 3',5'-cyclic monophosphate (cAMP), acting via protein kinase A, increas... more Adenosine 3',5'-cyclic monophosphate (cAMP), acting via protein kinase A, increases transport maximum of Na+-taurocholate cotransport within 15 min in hepatocytes (S. Grüne, L. R. Engelking, and M. S. Anwer. J. Biol. Chem. 268: 17734-17741, 1993); the mechanism of this short-term stimulation was investigated. Cycloheximide inhibited neither basal nor cAMP-induced increases in taurocholate uptake in rat hepatocytes, indicating that cAMP does not stimulate transporter synthesis. Studies in plasma membrane vesicles showed that taurocholate uptake was not stimulated by the catalytic subunit of protein kinase A but was higher when hepatocytes were pretreated with cAMP. Immunoblot studies with anti-fusion protein antibodies to the cloned Na+-taurocholate cotransport polypeptide (Ntcp) showed that pretreatment of hepatocytes with cAMP increased Ntcp content in plasma membranes but not in homogenates. Ntcp was detected in microsomes, endosomes, and Golgi fractions, and cAMP pretreatment resulted in a decrease only in endosomal Ntcp content. It is proposed that cAMP increases transport maximum of Na+-taurocholate cotransport, at least in part, by translocating Ntcp from endosomes to plasma membranes.
The American journal of physiology
The rat ileal apical Na+-dependent bile acid transporter (ASBT) and the liver Na+-taurocholate co... more The rat ileal apical Na+-dependent bile acid transporter (ASBT) and the liver Na+-taurocholate cotransporting polypeptide (Ntcp) are members of a new family of anion transporters. These transport proteins share limited sequence homology and almost identical predicted secondary structures but are localized to the apical surface of ileal enterocytes and the sinusoidal surface of hepatocytes, respectively. Stably transfected Madin-Darby canine kidney (MDCK) cells appropriately localized wild-type ASBT and Ntcp apically and basolaterally as assessed by functional activity and immunocytochemical localization studies. Truncated and chimeric transporters were used to determine the functional importance of the cytoplasmic tail in bile acid transport activity and membrane localization. Two cDNAs were created encoding a truncated transporter in which the 56-amino-acid COOH-terminal tail of Ntcp was removed or substituted with an eight-amino-acid epitope FLAG. For both mutants there was some loss of fidelity in basolateral sorting in that approximately 75% of each protein was delivered to the basolateral surface compared with approximately 90% of the wild-type Ntcp protein. In contrast, deletion of the cytoplasmic tail of ASBT led to complete loss of transport activity and sorting to the apical membrane. An Ntcp chimera in which the 56-amino-acid COOH-terminal tail of Ntcp was replaced with the 40-amino-acid cytoplasmic tail of ASBT was largely redirected (82.4 +/- 3.9%) to the apical domain of stably transfected MDCK cells, based on polarity of bile acid transport activity and localization by confocal immunofluorescence microscopy. These results indicate that a predominant signal for sorting of the Ntcp protein to the basolateral domain is located in a region outside of the cytoplasmic tail. These studies have further shown that a novel apical sorting signal is localized to the cytoplasmic tail of ASBT and that it is transferable and capable of redirecting a protein normally sorted to the basolateral surface to the apical domain of MDCK cells.
Gastroenterology
Malabsorption and deficiency of vitamin E causing neurological degeneration are common consequenc... more Malabsorption and deficiency of vitamin E causing neurological degeneration are common consequences of chronic childhood cholestatic liver disease. The objective of this study was to determine the long-term efficacy and safety of d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) in correcting vitamin E deficiency in children with chronic cholestasis who were unresponsive to other forms of oral vitamin E. Sixty vitamin E-deficient children with chronic cholestasis unresponsive to 70-212 IU.kg-1.day-1 of oral vitamin E were entered into a trial at eight centers in the United States. After initial evaluation, treatment was started with 25 IU.kg-1.day-1 of TPGS. Vitamin E status, neurological function quantitated by a specific scoring system, and clinical and biochemical parameters were monitored during therapy. All children responded to TPGS with normalization of vitamin E status. Neurological function, which had deteriorated before entry in the trial, improved in 25 patient...
Bile acids, which are present at physiological pH val- ues as bile salts, are synthesized in the ... more Bile acids, which are present at physiological pH val- ues as bile salts, are synthesized in the hepatocyte from cholesterol and secreted across the canalicular (apical) membrane into bile. Bile salts are taken up from blood across the sinusoidal (basal) membrane, in part metabolized within the hepatocyte, and se- creted into bile. The uphill bile salt transport across the canalicular
The Israel Medical Association journal : IMAJ, 2011
Primary liver masses in children may require intervention because of symptoms or concern about ma... more Primary liver masses in children may require intervention because of symptoms or concern about malignant transformation. To review the management and outcome of benign liver masses in children. We conducted a retrospective chart review of children with liver masses referred to our institution during the period 1997-2009. Benign liver masses were identified in 53 children. Sixteen of these children (30%) had hemangioma/infantile hepatic hemangioendothelioma (IHH) and 15 (28%) had focal nodular hyperplasia. The remainder had 6 cysts, 4 hamartomas, 3 nodular regenerative hyperplasia, 2 adenomas, 2 vascular malformations, and one each of polyarteritis nodosa, granuloma, hepatic hematoma, lymphangioma, and infarction. Median age at presentation was 6 years, and 30 (57%) were female. Masses were initially noticed on imaging studies performed for unrelated symptoms in 33 children (62%), laboratory abnormalities consistent with liver disease in 11 (21%), and palpable abdominal masses in 9 (...
Journal of lipid research, 2003
We investigated how cholesterol feeding regulates cholesterol 7alpha-hydroxylase (CYP7A1) via the... more We investigated how cholesterol feeding regulates cholesterol 7alpha-hydroxylase (CYP7A1) via the nuclear receptors farnesoid X receptor (FXR) and liver X receptor alpha (LXRalpha) in New Zealand white rabbits. After 1 day of 2% cholesterol feeding, when the bile acid pool size had not expanded, mRNA levels of the FXR target genes short-heterodimer partner (SHP) and sterol 12alpha-hydroxylase (CYP8B) were unchanged, indicating that FXR activation remained constant. In contrast, the mRNA levels of the LXRalpha target genes ATP binding cassette transporter A1 (ABCA1) and cholesteryl ester transfer protein (CETP) increased 5-fold and 2.3-fold, respectively, associated with significant increases in hepatic concentrations of oxysterols. Activity and mRNA levels of CYP7A1 increased 2.4 times and 2.2 times, respectively. After 10 days of cholesterol feeding, the bile acid pool size increased nearly 2-fold. SHP mRNA levels increased 4.1-fold while CYP8B declined 64%. ABCA1 mRNA rose 8-fold ...
Journal of lipid research, 2001
To study the effect of cholecystectomy on the regulation of classic and alternative bile acid syn... more To study the effect of cholecystectomy on the regulation of classic and alternative bile acid syntheses, gallbladder-intact (n = 20) and cholecystectomized (n = 20) New Zealand White rabbits were fed either chow or chow with 2% cholesterol (3 g/day). After 10 days, bile fistulas were constructed in half of each rabbit group to recover and measure the bile acid pool and biliary bile acid flux. After cholesterol feeding, the bile acid pool size increased from 268 +/- 55 to 444 +/- 77 mg (P < 0.01) with a 2-fold rise in the biliary bile acid flux in intact rabbits but did not expand the bile acid pool (270 +/- 77 vs. 276 +/- 62 mg), nor did the biliary bile acid flux increase in cholecystectomized rabbits. Ileal apical sodium-dependent bile acid transporter protein increased 46% from 93 +/- 6 to 136 +/- 23 units/mg (P < 0.01) in the intact rabbits but did not change in cholecystectomized rabbits (104 +/- 14 vs. 99 +/- 19 units/mg) after cholesterol feeding. Cholesterol 7alpha-hyd...
Journal of lipid research, 1984
Development of the capacity for hepatic biotransformation of potentially toxic, endogenous compou... more Development of the capacity for hepatic biotransformation of potentially toxic, endogenous compounds such as lithocholate may be dependent on induction by substrate or hormonal modulation. Our aim was to observe the ontogeny of hepatic sulfotransferase (ST) activity, a presumed detoxification pathway, and to determine the effect of substrate ingestion and cortisone administration on ST activity. Pregnant rats were fed a standard chow diet containing lithocholate; the maternal diet was continued during the suckling and weaning phase of the pups. Liver cytosol and serum were obtained from dams and from pups at weekly intervals from fetal life through 4 weeks of age. In controls, there was a progressive increase in hepatic ST activity from 6.2 +/- 2.9 pmol/mg protein per min, (mean +/- SEM) in fetal liver, 18.1 +/- 3.9 at 1 week, an 33.6 +/- 7.2 at 2 weeks to a peak of 56.4 +/- 11.8 at 3 weeks of age. In female rats older than 4 weeks of age, ST activity in hepatic cytosol was threefol...
Gut, 2004
Background: Obese Zucker rats (ZR) have been used as an experimental model for non-alcoholic fatt... more Background: Obese Zucker rats (ZR) have been used as an experimental model for non-alcoholic fatty liver disease and are particularly susceptible to various types of liver injury. Bile secretory function has not been assessed in ZR.Aim: To study bile secretion and expression of the main hepatobiliary transporters in ZR.Methods: Bile flow and biliary secretion of lipids and glutathione were determined
International journal of biochemistry and molecular biology, 2012
The human organic solute transporter (hOST) is a heterodimer composed of alpha and beta subunits.... more The human organic solute transporter (hOST) is a heterodimer composed of alpha and beta subunits. Physical association of hOSTα and β subunits is essential for their polarized basolateral plasma membrane localization and function in the export of bile acids and steroids. To understand the role of carboxyl- and amino-tails of OSTβ and mechanisms underlying membrane localization of hOST, the effects of tail deletion of the hOSTβ subunit and biological reagents on membrane distribution and transport function of hOST were investigated in stably transfected MDCK cells. After deletion of 35 amino acids from the amino-tail of hOSTβ, the efflux transport activity and polarized membrane distribution of the truncated hOSTβ was abolished. A co-immunoprecipitation study verified that the amino-tail of hOSTβ is essential for the association with hOSTα subunit. Treatments with acytochalasin D (interrupting ctin-filaments), bafilomycin A1 (inhibiting vacuolar H(+)-ATPase), brefeldin A (disrupting ...
Human molecular genetics, Jan 28, 2015
The control of transcription is regulated through the well-coordinated spatial and temporal inter... more The control of transcription is regulated through the well-coordinated spatial and temporal interactions between distal genomic regulatory elements required for specialized cell-type and developmental gene expression programs. With recent findings CFTR has served as a model to understand the principles that govern genome-wide and topological organization of distal intra-chromosomal contacts as it relates to transcriptional control. This is due to the extensive characterization of the DNase hypersensitivity sites, modification of chromatin, transcription factor binding sites and the arrangement of these sites in CFTR consistent with the restrictive expression in epithelial cell types. Here, we identified CHD6 from a screen among several chromatin-remodeling proteins as a putative epigenetic modulator of CFTR expression. Moreover, our findings of CTCF interactions with CHD6 are consistent with the role described previously for CTCF in CFTR regulation. Our results now reveal that the C...
Fibrocystic Diseases of the Liver, 2010
The cystic diseases of the liver are mostly autosomal recessive disorders with variable intrahepa... more The cystic diseases of the liver are mostly autosomal recessive disorders with variable intrahepatic biliary dilatation and increased hepatic fibrosis either as part of the underlying defect or as a result of liver damage from recurrent episodes of ascending cholangitis. Caroli disease (CD) denotes congenital saccular intrahepatic dilatation of the biliary tree. Caroli syndrome (CS) is a more common disorder
Clinics in Liver Disease, 2006
The hepatic fibrocystic diseases present with variable intrahepatic biliary abnormalities, which ... more The hepatic fibrocystic diseases present with variable intrahepatic biliary abnormalities, which range from portal tract enlargement and fibrosis to cystic formations. They may present as autosomal recessive or dominant polycystic kidney diseases, with associated dilatation of the renal collecting system, or as incompletely characterized cystic diseases. Symptoms from the liver disease often result from complications of fibrosis or dilated ducts/cyst (sludge, lithiasis, infection). The treatment is supportive, with careful attention to associated renal disease. Liver transplantation is an option in selected patients.
Journal of lipid research, 2002
We investigated the role of the orphan nuclear receptor farnesoid X receptor (FXR) in the regulat... more We investigated the role of the orphan nuclear receptor farnesoid X receptor (FXR) in the regulation of cholesterol 7alpha-hydroxylase (CYP7A1), using an in vivo rabbit model, in which the bile acid pool, which includes high affinity ligands for FXR, was eliminated. After 7 days of bile drainage, the enterohepatic bile acid pool, in both New Zealand White and Watanabe heritable hyperlipidemic rabbits, was depleted. CYP7A1 activity and mRNA levels increased while FXR was deactivated as indicated by reduced FXR protein and changes in the expression of target genes that served as surrogate markers of FXR activation in the liver and ileum, respectively. Hepatic bile salt export pump mRNA levels and ileal bile acid-binding protein decreased while sterol 12alpha-hydroxylase and sodium/taurocholate cotransporting polypeptide mRNA levels increased in the liver. In addition, hepatic FXR mRNA levels decreased significantly. The data, taken together, indicate that FXR was deactivated when the ...
Seminars in Liver Disease, 2011
Progressive familial intrahepatic cholestatic diseases encompass a group of autosomal recessive h... more Progressive familial intrahepatic cholestatic diseases encompass a group of autosomal recessive hereditary diseases, which usually present in infancy or childhood, with cholestasis of hepatocellular origin. The currently preferred nomenclature for the three PFIC disorders that have been characterized to date is FIC1 deficiency, BSEP deficiency, and MDR3 deficiency, relating to mutations in the specific genes involved in bile acid formation and transport. Since the first description of these diseases, extensive clinical, biochemical, and molecular studies have increased our understanding of the features specific to each one of them. This review focuses mainly on the liver histology, summarizing their characteristic pathologic features, the correlation to specific genotypes, and complications arising with disease progression.
Pharmaceutical Research, 2008
The human organic anion transporting polypeptide C (OATPC) is one of the major transport proteins... more The human organic anion transporting polypeptide C (OATPC) is one of the major transport proteins involved in the enterohepatic circulation of bile salts and plays an important role in vectorial transport of organic anions and drugs across hepatocytes. In this study, the effects of biological reagents on the membrane localization of OATPC were investigated by confocal microscopy and estrone-3-sulfate transport. Our results demonstrated that the functional membrane expression of fluorescent chimera OATPC-GFP was achieved in non-polarized (COS7 and HEK293) and polarized (MDCK) cells. Both brefeldin A (a Golgi complex disruptor) and bafilomycin A1 (an inhibitor of vacuolar H+-ATPase) treatment significantly decreased the polarized membrane trafficking and markedly reduced the uptake of estrone-3-sulfate ( approximately 40-90%) in OATPC-GFP transfected cells, suggesting that membrane sorting of hOATPC-GFP was mediated by Golgi complex and vacuolar H+-ATPase-related vesicle transport pathways. Treatment with 8-Br-cAMP (a cAMP analog) stimulated OATPC-GFP membrane localization and enhanced estrone-3-sulfate uptake by approximately 20%. The protein kinase A (PKA) inhibitors (H89 and KT5720), but not a PKG inhibitor, blocked the polarized membrane expression of OATPC-GFP and reduced estrone-3-sulfate transport activity. The simultaneous treatment of cells with PKA activator/inhibitor and bafilomycin A1 demonstrated that bafilomycin A1 did not change the effects of 8-Br-cAMP and H89 on the membrane localization of OATPC-GFP compared with the use of 8-Br-cAMP and H89 alone. These data suggest that a cAMP-PKA sensitive membrane sorting pathway for OATPC-GFP is independent of the vacuolar H+-ATPase associated (bafilomycin A1 sensitive) vesicle mediated membrane sorting pathway. In contrast, with combined treatment with brefeldin A, neither the PKA-activator (8-Br-cAMP) nor the inhibitor (H89) further altered the plasma membrane expression and transport activity of OATPC-GFP compared with brefeldin A treatment alone. These data suggest that the cAMP-PKA regulation of OATPC membrane expression involves the Golgi complex. When the Golgi apparatus was disrupted by brefeldin A treatment, the effects of cAMP-PKA on the Golgi-to-basolateral surface sorting process of OATPC was also diminished. In summary, the plasma membrane localization of human OATPC is mediated by Golgi complex and vacuolar H+-ATPase vesicle mediated membrane sorting pathways. cAMP-PKA regulates sorting process through the Golgi complex but not the vacuolar H+-ATPase associated vesicular pathway.
PEDIATRICS, 2009
WHAT'S KNOWN ON THIS SUBJECT: Nonadherence increases morbidity and mortality rates in the posttra... more WHAT'S KNOWN ON THIS SUBJECT: Nonadherence increases morbidity and mortality rates in the posttransplant setting. Adolescents are more prone to nonadherence. TM has been used with efficacy for a variety of chronic diseases, such as diabetes mellitus and asthma.