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Biomedical subjects

K Schwarz

Publications and source records attributed to K Schwarz.

At least 91 records · Page 5Linked to original sources
PubMed1998

Orthotopic liver transplantation in patients with biliary atresia and situs inversus.

Situs inversus (SI) and the polysplenia syndrome (PS) occur relatively frequently in patients with biliary atresia, the largest subgroup of pediatric liver transplantation patients. We present two cases of orthotopic liver transplantation (OLT) in pediatric patients with SI. One had SI totalis, where a normal liver was placed in the left upper quadrant (LUQ) with the right lobe overlying the vertebral column. The second had PS and isolated SI of the liver, and a living-related left-lateral-segment graft was placed in the LUQ. Although multiple, often unpredictable vascular and intestinal anomalies occur frequently in association with SI, particularly in the setting of the PS, these cases, as well as several others recently reported, reveal that these anomalies can be managed successfully by a variety of technical modifications of the standard OLT technique. Likewise, concerns about the placement of a situs solitus liver in the midline or LUQ position of a SI abdomen have proved to be unfounded.

Biliary Atresia↗
PubMed1998

The proteasome inhibitor lactacystin prevents the generation of an endoplasmic reticulum leader-derived T cell epitope.

The presentation of viral antigens on MHC class I molecules requires their intracellular fragmentation into peptides of appropriate length and anchor residue positions. Evidence has accumulated that the proteasome is the endoprotease in charge of the generation of MHC class I ligands in the cytoplasm. The generation of T cell epitopes derived from the leader peptides of endoplasmic reticulum (ER) targeted proteins, however. has been reported to be independent of the proteasome. Here we show that the H-2Db restricted antigen presentation of the immunodominant T cell epitope derived from the ER leader of the glycoprotein of lymphocytic choriomeningitis virus (LCMV) is completely abolished by administration of the proteasome inhibitor lactacystin. Thus our data support the role of the proteasome in class I restricted antigen processing and extend it to an ER leader derived epitope from a viral glycoprotein.

Acetylcysteine↗
PubMed1998

DNA ligase IV is essential for V(D)J recombination and DNA double-strand break repair in human precursor lymphocytes.

Nonhomologous DNA end joining (NHEJ) is the major pathway for repairing double-strand DNA breaks. V(D)J recombination is a double-strand DNA breakage and rejoining process that relies on NHEJ for the joining steps. Here we show that the targeted disruption of both DNA ligase IV alleles in a human pre-B cell line renders the cells sensitive to ionizing radiation and ablates V(D)J recombination. This phenotype can only be reversed by complementation with DNA ligase IV but not by expression of either of the remaining two ligases, DNA ligase I or III. Hence, DNA ligase IV is the activity responsible for the ligation step in NHEJ and in V(D)J recombination.

Alleles↗
PubMed1998

Feasibility of cellular adoptive immunotherapy for Epstein-Barr virus-associated lymphomas using haploidentical donors.

Epstein-Barr virus (EBV)-associated lymphomas following bone marrow or solid organ transplantation are often sensitive to immunomodulatory therapies. These have included withdrawal or reduction in immunosuppressive therapy in the solid organ transplant setting and adoptive cellular therapies in the bone marrow transplant (BMT) setting. We describe a strategy for generating EBV-specific cytotoxic T cell therapy lines with substantial killing activity against haploidentical targets. Weekly stimulation of peripheral blood mononuclear cells (PBMCs) for 3 weeks with the irradiated cells of an autologous EBV-transformed B lymphoblastoid cell line (B-LCL), followed by stimulation in the presence of IL-2, yielded T cell lines that were cytolytic for haploidentical B-LCLs but did not lyse haploidentical targets not expressing EBV antigens.

Adoptive Transfer↗
PubMed1997

Role of ADP-ribosylation in activated monocytes/macrophages.

Stimulating monocytes/macrophages with bacterial lipopolysaccharide (LPS) results in TNF-alpha, IL-1, IL-6 and nitrite (NO2-) formation. Inhibitors of poly(ADP-ribose)polymerase inhibit release of these mediators by preventing mRNA expression indicating that ADP-ribosylation plays a crucial role in the synthesis of these mediators. Furthermore we present evidence that ADP-ribosylation is involved in modifying cellular proteins. In murine macrophages a 33 kDa cytosolic protein could be identified that in response to LPS changed its state of ADP-ribosylation, and in human monocytes we showed that the inhibitor nicotinamide prevents LPS induced phosphorylation of two cytosolic proteins of 36 kDa and 38 kDa (p36/38) LPS. Taken together these data indicate that protein modification by ADP-ribosylation may control cellular processes involved in distinct steps of monocyte/macrophage activation.

Adenosine Diphosphate Ribose↗
PubMed1997

Steroid withdrawal in tacrolimus (FK506)-treated pediatric liver transplant recipients.

PURPOSE: The use of steroids in pediatric transplant recipients is associated with significant adverse side effects. The authors examined the feasibility of steroid withdrawal in patients who underwent immunosuppression with tacrolimus (FK506; FK). METHODS: All pediatric liver transplant recipients on FK greater than 6 months were evaluated for steroid withdrawal. FK was administered 0.3 mg/kg/d in two divided doses. Steroids were tapered as tolerated with goals of 0.2 to 0.3 mg/kg/d at 6 weeks, 0.2 to 0.3 mg/kg every other day at 3 months, and complete withdrawal after 6 months. Steroid bolus and taper were instituted for enzyme elevation or rejection during biopsy. RESULTS: Twenty-nine patients underwent evaluation for steroid withdrawal. Five patients could not be placed on FK506 monotherapy (chronic, recurrent rejection or LPD). The remaining 24 had steroids withdrawn. Tweleve (50%) had no sequelae and continue on FK monotherapy (mean, 22 months off steroids). The other 12 required intermittent steroid therapy for presumed or biopsy-proven rejection (n = 7), graft dysfunction (FK toxicity, n = 2), lymphoproliferative disease necessitating reduction in FK (n = 2) or exacerbations of asthma (n = 1). Five of these 12 patients are now on FK monotherapy (mean, 6 months) for a total of 17 of the 24 (71%) currently off steroids. CONCLUSION: FK monotherapy can be successfully used to withdraw steroid therapy in the majority of pediatric liver transplant recipients with few sequelae.

Graft Rejection↗
PubMed1997

Expression of biglycan, decorin and proteoglycan-100/CSF-1 in normal and fibrotic human liver.

The immunohistochemical expression of the three small chondroitin/dermatan sulphate proteoglycans biglycan, decorin and proteoglycan-100 (PG-100), the proteoglycan form of colony-stimulating factor-1 (CSF-1), was studied in normal and fibrotic human liver. In normal liver tissue biglycan and decorin were clearly seen in the space of Disse, which was in contrast to a faint staining of PG-100. Biglycan and decorin were additionally detected around small bile ducts and in vessel walls. In patients with HBs-Ag positive, chronic active hepatitis decorin as well as biglycan showed strong immunoreactivity in fibrotic areas. In contrast to normal liver, PG-100 was visualized in bile duct epithelia. Therefore, PG-100 could serve as an immunohistochemical marker of the involvement of the bile duct system in chronic active hepatitis and progressive liver fibrosis.

Adult↗
PubMed1997

Angiotensin I-converting enzyme-gene-polymorphism: relationship to albumin excretion and blood pressure in pediatric patients with type-I-diabetes mellitus.

The purpose of this study was the evaluation of a predictive genetic marker for nephropathy and hypertension in patients with type-I-diabetes mellitus (IDDM). The study was performed on 247 pediatric patients with IDDM. The mean age was 15.5 years (range 3.1-29.3), the mean duration of diabetes was 7.6 years (range 0.1-25.7). Age-related blood pressure and nocturnal albumin excretion rate were compared with the insertion/deletion-(I/D) polymorphism of the angiotensin-I converting enzyme gene. The genotype distribution did not differ significantly between IDDM patients (ID 48%, D 28%, I 24%) and the control group (ID 44%, D 37%, I 19%). Neither in the entire group, nor in patients with IDDM for more than 5 years, was a correlation found bet-ween allele distribution and albumin excretion rate. No correlation was found between genotype and blood pressure. When patients with a chronological age above 12 years were analysed separately, the genotype distribution between the groups with normal and elevated blood pressure showed no significant difference. The previously reported association of the I/D-polymorphism with nephropathy could not be confirmed in this study. The development of microalbuminuria, nephropathy and hypertension will be followed in our pediatric patients.

Adolescent↗
PubMed1997

Lack of evidence for rotavirus by polymerase chain reaction/enzyme immunoassay of hepatobiliary samples from children with biliary atresia.

The purpose of this study was to analyze hepatobiliary samples of patients with biliary atresia for rotavirus groups. A, B, and C, because group A rotavirus had been used to produce an animal model of the disease and group C rotavirus had been found in hepatobiliary samples from one group of patients. Biliary remnants and liver tissue from 10 biliary atresia and 14 control patients with other liver diseases were examined for rotavirus groups A, B, and C using nonisotopic, reverse transcriptase polymerase chain reaction enzyme immunoassay. Biliary atresia patients had a median age of 3 mo and were from a confined geographic area. Rotaviral stocks from groups A and C were used as polymerase chain reaction-positive controls. The limits of detection for rotaviral RNA from these two groups were respectively, 5 plaque-forming units and 50 tissue culture infectious doses (ID50). Tissue culture was 100-fold less sensitive for groups A and C than the polymerase chain reaction. The nested nonisotopic probes hybridized in solution only with their homologous target DNAs as determined by the enzyme immunoassay, or by Southern blot hybridization. Although it was possible to detect mRNA from a beta-actin housekeeping gene in all of the hepatobiliary samples, no evidence of rotaviral RNA was found in either the biliary atresia or the negative control group. In conclusion, rotavirus is not a common viral etiology of biliary atresia.

Adolescent↗
PubMed1996

RAG mutations in human B cell-negative SCID.

Patients with human severe combined immunodeficiency (SCID) can be divided into those with B lymphocytes (B+ SCID) and those without (B- SCID). Although several genetic causes are known for B+ SCID, the etiology of B- SCID has not been defined. Six of 14 B- SCID patients tested were found to carry a mutation of the recombinase activating gene 1 (RAG-1), RAG-2, or both. This mutation resulted in a functional inability to form antigen receptors through genetic recombination and links a defect in one of the site-specific recombination systems to a human disease.

B-Lymphocytes↗
PubMed1996

Two novel missense and frameshift mutations in exons 5 and 6 of the purine nucleoside phosphorylase (PNP) gene in a severe combined immunodeficiency (SCID) patient.

Four percent of human severe combined immunodeficiency cases are caused by a deficiency of the enzyme purine nucleoside phosphorylase (PNP). In this study we investigated the molecular basis for this rare autosomal recessive disease. Sequence analyses led to the identification of two new mutations in the PNP gene: an A to G transition in exon 5, which leads to the substitution of tyrosine 192 by a cysteine residue, and a 1-bp deletion in exon 6, which causes premature translation termination of the PNP protein. Both PNP mutations affect predicted major structural motifs of the protein and result in post-translation instability of the enzyme.

Alleles↗
PubMed1996

Isolated X-linked thrombocytopenia in two unrelated families is associated with point mutations in the Wiskott-Aldrich syndrome protein gene.

The Wiskott-Aldrich syndrome (WAS) is characterized by defective platelet and lymphocyte function associated with eczema and increased susceptibility to malignancies. It is caused by mutations of the WAS protein-encoding gene (WASP). X-lined thrombocytopenia, defined by low platelet counts and volume, may be an allelic variant of WAS. In patients with XLT from two unrelated families, WASP gene defects were identified by single-strand conformational polymorphism and by sequencing. Point mutations in exon 2 of the WASP gene were found in the patients from both families in which XLT segregated. Several obligate heterozygote female members of these families display a random pattern of X inactivation in their peripheral blood leukocytes. This study shows that XLT may be caused by mutations of the WASP, thus representing an allelic variant of WAS.

Adult↗
PubMed1996

Liver transplantation in infants younger than 1 year of age.

OBJECTIVE: The authors report on experience with liver transplantation for infants younger than 1 year of age. SUMMARY BACKGROUND DATA: Over the last 15 years, orthotopic liver transplant has become the only lifesaving procedure available for infants with end-stage liver disease. Many transplant centers initially required infants to reach a specific weight or age to minimize morbidity and mortality. Size-appropriate infant donors also were uncommon. As a result, many children, in the first few years of life, died of their disease. The availability of reduced-size cadaveric and living-related liver transplants has offered the ability to transplant the young infant with liver failure. METHODS: The authors instituted a program to aggressively transplant infants with liver failure in the first year of life using both cadaveric and living-related liver donors. RESULTS: Between June 1991 and January 1995, 13 infants were transplanted for rapidly progressive liver failure. Infant age ranged from 4 to 11 months (mean, 7.5 months). The cause of liver failure included biliary atresia (11), alpha 1-antitrypsin deficiency (1), and liver failure secondary to echovirus 7 (1). The United Network for Organ Sharing status at the time of transplant ranged from status 4, intensive care unit bound (4 patients); status 3, hospitalized (4 patients); or status 2, failing at home (5 patients). Six patients (46%) received cadaveric whole organ (2) or segmental transplants (4). Seven patients (54%) received left lateral segment living-related transplants from parental donors. After operation, patients received cyclosporine or FK506-based immunosuppression. Three patients (23%) required four retransplants (two cadaveric for primary nonfunction; one living-related for graft thrombosis in the face of fungal infection and bile leak). Postoperative complications included primary nonfunction (15%), rejection (85%), graft vascular thrombosis (15%, two of three revascularized successfully), bacterial and fungal infections (77%), and viral infections (46%). Epstein-Barr virus-associated lymphoproliferative developed in two patients (15%). Intestinal perforation requiring reoperation developed in two patients (15%). Bile leaks requiring reoperation or transhepatic stinting or both developed in three patients (23%). Two patients died in the perioperative period (< 1 month) from a combination of primary nonfunction or graft thrombosis and sepsis. Overall survival was 85%, ranging from 11.0 months to 4.5 years. CONCLUSIONS: Orthotopic liver transplantation in infants younger than 1 year of age poses significant challenges from technical and infectious complications. Despite these barriers, overall patient survival is comparable to that of older children and adults.

Biliary Atresia↗