PubMed Health⌕ Search

Biomedical subjects

D A Rouch

Publications and source records attributed to D A Rouch.

32 records · Page 2Linked to original sources
PubMed1990

A family of ATPases involved in active partitioning of diverse bacterial plasmids.

Low copy-number bacterial plasmids F (the classical Escherichia coli sex factor) and prophage P1 encode partitioning functions which may provide fundamental insights into the active processes which ensure that bacterial genomes are segregated to both daughter cells prior to cell division. These partitioning systems involve two proteins: ParA and ParB. We report that incC from the broad host-range plasmid RK2 is a member of the family of ParA partitioning proteins and that these proteins (as well as related proteins encoded by plasmids from Agrobacterium tumefaciens and Chlamydia trachomatis) contain type I nucleotide-binding motifs. Also, we show that the cell division inhibitor MinD is homologous to members of the ParA family. Sequence comparisons of ParB proteins suggest that they may contain sites for phosphorylation. We propose that ATP hydrolysis by the ParA protein may result in phosphorylation of the ParB protein, thereby causing a conformational shift necessary to separate paired plasmid molecules at the cell division plane.

Adenosine Triphosphatases↗
PubMed1990

Choledochocholedochostomy without a T tube or internal stent in transplantation of the liver.

Different techniques have been used for biliary reconstruction in transplantation of the liver. Early techniques of cholecystodoudenostomy and cholecystojejunostomy had high rates of biliary complications often with associated mortality. Today, most centers use a choledochocholedochostomy with a T tube (CC-T) or Roux-en-Y choledochojejunostomy (RYCJ) for biliary reconstruction in hepatic transplantation with a low mortality rate but still significant morbidity. In our early experience at the University of Chicago, we used CC-T as the procedure of choice and RYCJ in the remaining instances. However, it was noted that a large number of biliary complications in the CC-T group were related to the use of T tubes, which prompted us to consider the use of primary anatomosis without tube drainage or stenting (CC). We reviewed 136 transplants with a graft survival rate of greater than two weeks. The over-all complication rates for each group were 38 CC, 18 per cent; 26 CC-T, 35 per cent, and 72 RYCJ, 21 per cent. One patient died as a direct result of a biliary complication. The main difference between CC and CC-T was early biliary complications (5 versus 31 per cent, p less than 0.02 most were T-tube related. We advocate the use of CC (without a T tube) when-possible. We recommend RYCJ whenever reoperation and biliary revision are required. We have found that both CC and RYCJ can be used safely for biliary reconstruction in hepatic transplantation.

Adult↗
PubMed1989

Nucleotide sequence analysis of IS256 from the Staphylococcus aureus gentamicin-tobramycin-kanamycin-resistance transposon Tn4001.

Resistance to the aminoglycosides gentamicin, tobramycin and kanamycin (GmTmKmR) in Australian clinical strains of Staphylococcus aureus is commonly carried on the composite transposon Tn4001. The resistance gene aacA-aphD of Tn4001, which encodes a bifunctional AAC(6')-APH(2") modifying enzyme, is flanked by two 1324-bp inverted repeats, IS256L and IS256R, that are identical in sequence. Analysis of the IS256 sequence revealed structural features characteristic of IS elements including 26-bp imperfect terminal inverted repeats and a single open reading frame with coding capacity for a 45.6 kDa protein. The nucleotide sequence of IS256 described here, together with the sequence of the aacA-aphD gene reported previously [Rouch et al., J. Gen. Microbiol. 133 (1987) 3039-3052], completes the entire sequence of Tn4001, which totals 4566 bp.

Amino Acid Sequence↗
PubMed1989

IS257 from Staphylococcus aureus: member of an insertion sequence superfamily prevalent among gram-positive and gram-negative bacteria.

The nucleotide sequences for the IS257 family of insertion sequences from Staphylococcus aureus were compared with those of the ISS1 family from Streptococcus lactis and the IS15 family which is widespread amongst Gram-negative bacteria. These elements have a striking degree of similarity in both their putative transposase polypeptide sequences and their nucleotide sequences (40 to 64% between pairs), including 12 out of 14 bp conservation in their terminal inverted repeats. The evolutionary distance between the IS15 family and the IS257 and ISS1 families of Gram-positive origin is approximately twice that between the IS257 and ISS1 families. Analysis of base substitutions in the three sequences has provided insights into the effect of selection for the G + C content of immigrant genes to conform to that of their hosts, and into the evolution of biases in overall amino acid composition of cellular proteins in prokaryotes and eukaryotes. The IS257, ISS1, IS15 families form a superfamily of insertion sequences that has been involved in the spread of a number of antimicrobial resistance determinants in Gram-positive and Gram-negative pathogens.

Amino Acid Sequence↗
PubMed1989

Trimethoprim resistance transposon Tn4003 from Staphylococcus aureus encodes genes for a dihydrofolate reductase and thymidylate synthetase flanked by three copies of IS257.

Trimethoprim resistance mediated by the Staphylococcus aureus multi-resistance plasmid pSK1 is encoded by a structure with characteristics of a composite transposon which we have designated Tn4003. Nucleotide sequence analysis of Tn4003 revealed it to be 4717 bp in length and to contain three copies of the insertion element IS257 (789-790 bp), the outside two of which are flanked by directly repeated 8-bp target sequences. IS257 has imperfect terminal inverted repeats of 27-28 bp and encodes for a putative transposase with two potential alpha-helix-turn-alpha-helix DNA recognition motifs. IS257 shares sequence similarities with members of the IS15 family of insertion sequences from Gram-negative bacteria and with ISS1 from Streptococcus lactis. The central region of the transposon contains the dfrA gene that specifies the S1 dihydrofolate reductase (DHFR) responsible for trimethoprim resistance. The S1 enzyme shows sequence homology with type I and V trimethoprim-resistant DHFRs from Gram-negative bacteria and with chromosomally encoded DHFRs from Gram-positive and Gram-negative bacteria. 5' to dfrA is a thymidylate synthetase gene, designated thyE.

Amino Acid Sequence↗
PubMed1989

Experience with radical resection in the management of proximal bile duct cancer.

Multiple surgical and nonsurgical approaches have been advocated for the treatment of proximal bile duct cancer. However, survival appears longest when a resection can be performed. Fifteen patients treated at a university center were managed with an aggressive surgical approach. Resection of the tumor was performed in 13 of 15 patients (87%). Of the patients undergoing resection, major hepatic resection was performed in 8 (62%), while excision of vessels with reconstruction was performed in 5 (38%). Eleven of the 13 resected patients (85%) were discharged from the hospital. Clinical symptoms of recurrent disease occurred between 3 and 36 months after surgery in 7 patients, 6 of whom have died. Three other patients are alive at 5, 21, and 36 months without clinical evidence of recurrence. There was no correlation between the completeness of resection 'and the duration of disease-free survival. These results demonstrate that radical resection of high bile duct tumors can be accomplished with an acceptable early mortality rate, thereby extending the benefits of resection to a higher proportion of patients. While resection is clearly effective at controlling local disease and providing palliation of jaundice, surgical cure remains exceptional. Further improvement in the therapy of bile duct cancer must await development of more effective multi-modality approaches.

Adult↗
PubMed1989

Liver transplantation.

A multidisciplinary approach is necessary in addressing the needs of a patient with end-stage liver disease. The development of the liver transplant program at MHI was a natural extension of the transplant and critical care programs already in place. The case report described exemplifies that valuable input from ancillary support groups is necessary for a successful liver transplant program. Experience gained in the area of liver transplantation not only benefits liver transplant patients but also extends to other areas of clinical medicine. One year ago, an Indiana resident had to travel out of state to receive this specialized form of care. Today this is no longer the case.

Humans↗
PubMed1988

Multiresistant Staphylococcus aureus: genetics and evolution of epidemic Australian strains.

Molecular and genetic analysis of multiresistant isolates of Staphylococcus aureus from widely separated hospitals in Australia has demonstrated that these are clearly related, and that the predominant strains possess up to three different plasmids, which fall into the following classes: (i) small 1.6 kb plasmids, such as pSK3, which are phenotypically cryptic, (ii) 4.5 kb chloramphenicol resistance plasmids, such as pSK2, and (iii) the pSK1 family of multiresistance plasmids, which range in size from 20 to 42 kb and variously encode resistance to antiseptics and disinfectants, trimethoprim (Tpr), penicillin (Pcr) and the aminoglycosides gentamicin, tobramycin and kanamycin (Gmr Tmr Kmr). Gmr Tmr Kmr is encoded on the pSK1 family plasmids by transposon Tn4001, which was also detected on the chromosomes of some clinical isolates. Tn4001 is composed of inverted repeats of the insertion sequence IS256; these repeats flank a Gmr Tmr Kmr sequence encoding for a 57,000 dalton bifunctional protein with aminoglycoside acetyltransferase [AAC(6')] and phosphotransferase [APH(2")] activities. A Tn4001-like structure, which is defective in transposition but encodes for a Gmr Tmr Kmr determinant homologous with that on Tn4001, occurs on conjugative plasmids from strains isolated in North America. Physical studies indicate that Pcr, via a beta-lactamase, and Tpr, via a trimethoprim-insensitive dihydrofolate reductase (DHFR), are also encoded on the pSK1 family by transposons; these transposons have been designated Tn4002 and Tn4003, respectively. Tn4003 is flanked by direct repeats of the insertion sequence IS257. The evolution of the pSK1 family of multiresistance plasmids is traced through the transposition and genetic rearrangement of resistance determinants. Transposition and genetic rearrangement have also contributed to the evolution of a multiresistant chromosome in Staph. aureus. In the majority of contemporary multiply resistant Staph. aureus strains the determinants for resistance to erythromycin (Emr), fusidic acid, methicillin (Mcr), minocycline, rifampicin, spectinomycin, streptomycin, sulphonamides, tetracycline (Tcr), cadmium (Cdr), and mercury (Hgr) are chromosomally encoded; these strains also possess chromosomally encoded Pcr, via a beta-lactamase. Evidence indicates that some of these determinants, Pcr, Cdr, Hgr, and Tcr, were plasmid encoded in isolates collected from Australian hospitals prior to 1970. Through transposition and site-specific integration, they have since been acquired by the chromosome in more recent Staph. aureus strains.(ABSTRACT TRUNCATED AT 400 WORDS)

Australia↗
PubMed1988

Liver transplantation, including the concept of reduced-size liver transplants in children.

Since the establishment of a clinical program in liver transplantation in 1984, 162 liver transplants have been performed in 131 patients (78 adults, 53 children). The patient mortality rate while waiting for a suitable organ has been 8% for adults and only 4% for children (25-46% reported in the literature). The low pediatric mortality is a result of the use of reduced-size liver transplants. A total of 14 procedures have been performed in recipients whose clinical condition was deteriorating and for whom no full-size graft could be located. Of 14 children, 13 were less than 3 years of age. Patient survival is 50%, comparable to survival of high-risk recipients of full-size livers. Using reduced-size liver grafting in a transplant program can lower mortality for children awaiting a transplant by overcoming size disparity. Reduced-size liver grafting will allow more effective use of donor resources and provide a potential avenue of research for organ splitting and living related donation.

Adolescent↗
PubMed1988

Liver transplantation with reduced-size donor organs.

Orthotopic liver transplantation (OLT) of the pediatric patient is often limited by the availability of a size-matched donor organ. Use of reduced liver transplantation (RLT) can increase the proportion of candidates transplanted and may reduce overall mortality. We report herein the initial clinical application of RLT in the United States. Indications for RLT included fulminant hepatic failure (n = 2), acute hepatic artery thrombosis (n = 3), and chronic liver disease unresponsive to inpatient support and more than 30 days on transplant list (n = 4). Donor hepatectomy was performed using standard techniques. Formal hepatic resection was performed ex-vivo to create a size-matched graft, from the larger donor organ, which was implanted in the orthotopic position. Between 11/84 and 4/87, 70 pediatric patients were evaluated for OLT, and 33 of these were transplanted. During this period only 5 patients (7%) died awaiting OLT. Of 33 patients treated at the University of Chicago, 5 received RLT. Donor: recipient weight ratios ranged from 2:1 to 8.1:1. For RLT median operative blood loss was 1.7 blood volumes (range 0.5-11.7) with an operative time of 9.3 + 3.5 hr. Acceptable early graft function was observed in five patients, all of whom were discharged from the hospital. Four of these five patients are alive between 2 and 48 months after transplantation. Marginal graft function with cholestasis and coagulopathy was associated with acute intracranial hemorrhage and neurologic death in one case. One patient died intraoperatively with non-function caused by the use of a liver from a donor with steatosis and a poor size match. Another patient died on day 5 with primary nonfunction and persistent hemorrhage. Systemic cytomegalovirus infection was the cause of death in the other two cases. RLT can provide life-sustaining liver function in urgent clinical settings. The graft can serve as a temporary or permanent liver replacement. With evolution of the technique RLT could eventually be offered to more elective candidates and increase the utilization of available donors by reducing size limitations in OLT.

Adolescent↗
PubMed1988

The successful management of portal vein thrombosis after hepatic transplantation with a splenorenal shunt.

Portal vein thrombosis is an infrequent complication after hepatic transplantation, but is quite dramatic when it occurs. It is usually managed by retransplantation with a significant mortality rate. We present a patient in whom portal vein thrombosis after hepatic transplantation was ultimately managed by a splenorenal shunt. The portal vein thrombosis was manifested by bleeding esophageal varices and, yet, normal hepatic function obviated the need for a new graft (one was not readily available). To the best of our knowledge, this is the first presentation of a patient with a transplant of the liver with acute portal vein occlusion and maintained hepatic function who has been successfully managed by a portosystemic shunt.

Child↗
PubMed1987

The aacA-aphD gentamicin and kanamycin resistance determinant of Tn4001 from Staphylococcus aureus: expression and nucleotide sequence analysis.

The aacA-aphD aminoglycoside resistance determinant of the Staphylococcus aureus transposon Tn4001, which specifies resistance to gentamicin, tobramycin and kanamycin, has been cloned and shown to express these resistances in Escherichia coli. The determinant encoded a single protein with an apparent size of 59 kDa which specified both aminoglycoside acetyltransferase [AAC(6')] and aminoglycoside phosphotransferase [APH(2")] activities. Nucleotide sequence analysis of the determinant showed it to be capable of encoding a 479-amino-acid protein of 56.9 kDa. analysis of Tn1725 insertion mutants of the determinant indicated that resistance to tobramycin and kanamycin is due to the AAC activity specified by, approximately, the first 170 amino acids of the predicted protein sequence and is consistent with the gentamicin resistance, specified by the APH activity, being encoded within the C-terminal region of the protein. Comparison of the C-terminal end of the predicted amino acid sequence with the reported sequences of 13 APHs and a viomycin phosphotransferase revealed a region which is highly conserved among these phosphotransferases.

Amino Acid Sequence↗
PubMedDate not supplied

Intraoperative ultrasound of hepatic tumors.

Intraoperative ultrasound (IOUS) scanning of liver masses was compared with those of preoperative computed tomography (CT) and intraoperative palpation. Between March 1989 and May 1991, 24 patients underwent 25 IOUS procedures during laparotomy. Intraoperative ultrasound provided more information than the other modalities in 10 patients (40%) and affected operative management in eight patients (32%). It was concluded that IOUS, when used in conjunction with CT and palpation, is an important technique in the surgical management of patients with hepatic neoplasms.

Adult↗