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Biomedical subjects

S E Mitchell

Publications and source records attributed to S E Mitchell.

At least 37 records · Page 2Linked to original sources
PubMed1998

Species-specific repeat units in the intergenic spacer of the ribosomal RNA cistron of Anopheles aquasalis Curry.

A genomic DNA library of Anopheles aquasalis Curry was screened for clones that hybridized more intensely to DNA from A. aquasalis than to DNA from A. benarrochi Gabaldon, Cova Garcia, and Lopez, A. konderi Galvao and Damasceno, A. nuneztovari Gabaldon cytotypes A, B, and C, A. oswaldoi (Peryassu), A. rangeli Gabaldon, Cova Garcia, and Lopez, or A. trinkae Faran. Two specific clones (2.5 kilobasepairs [kbp] and 3.0 kbp) from A. aquasalis were isolated. Both A. aquasalis-specific clones were from the intergenic spacer region of the ribosomal RNA (rRNA) cistron. Upon digestion with Rsa I, a 900-bp fragment from the clone AA-1 hybridized specifically to A. aquasalis DNA. Analysis of the DNA sequence of this fragment revealed four tandemly repeated 36-bp units. Three of these repeat units were identical, and the fourth was 94% identical to the others. The DNA sequence of a highly conserved region of these repeats was used to synthesize an oligonucleotide probe specific to A. aquasalis.

Animals↗
PubMed1997

ob gene expression and secretion of leptin following differentiation of rat preadipocytes to adipocytes in primary culture.

Expression of the ob gene and production of leptin have been examined on differentiation of rat fibroblastic preadipocytes to adipocytes in primary culture. Preadipocytes were obtained from the inguinal fat pad of suckling rats, and following differentiation the cells contained lipid droplets and the mRNAs for both lipoprotein lipase and adipsin were detected by Northern blotting. ob mRNA was not, however, detected on Northern blots, but analysis by RT-PCR indicated that the ob gene was expressed, particularly after differentiation. Measurement of leptin in the culture medium by ELISA showed that the ob gene product was secreted by adipocytes from approximately 4 days after the induction of differentiation. Leptin production was sustained over a 2-week period with a peak at 8-10 days post-induction. Dexamethasone stimulated leptin production, while an inhibition was observed with the beta-adrenoceptor agonist isoprenaline. These results demonstrate that following the differentiation of fibroblastic preadipocytes to adipocytes in primary culture, leptin is secreted with the cells responding to stimuli which regulate production of the hormone.

Adipocytes↗
PubMed1997

A multiplex PCR for identifying Shiga-like toxin-producing Escherichia coli O157:H7.

A multiplex PCR assay specifically detecting Escherichia coli O157:H7 was developed by employing primers amplifying a DNA sequence upstream of E. coli O157:H7 eaeA gene and genes encoding Shiga-like toxins (SLT) I and II. Analysis of 151 bacterial strains revealed that all E. coli O157:H7 strains were identified simultaneously with the SLT types and could be distinguished from E. coli O55:H7 and E. coli O55:NM, and other non-O157 SLT-producing E. coli strains. Primer design, reaction composition (in particular, primer quantity and ratios), and amplification profile were most important in development of this multiplex PCR. This assay can serve not only as a confirmation test but also potentially can be applied to detect the pathogen in food.

Adhesins, Bacterial↗
PubMed1997

Laparoscopic cholecystectomy-related bile duct injuries: a health and financial disaster.

OBJECTIVE: This study was designed to evaluate the total costs associated with repair of laparoscopic cholecystectomy (LC)-related bile duct injuries. SUMMARY BACKGROUND DATA: The popularity of LC with both patients and surgeons is such that this procedure now exceeds open cholecystectomy by a ratio of approximately 4 to 10:1. However, costs associated with LC-related injuries, particularly regarding treatment patterns, have up to now not been explored fully. METHODS: The complete hospital and interventional radiology (IR) billing records for 49 patients who have completed treatment for laparoscopic cholecystectomy-related bile duct injuries were divided into 8 categories. These records were totaled for comparison of costs between patient groups that experienced different injuries and treatment patterns. RESULTS: Patients with LC-related bile duct injuries were billed a mean of $51,411 for all care related to repair of their bile duct injury. Patients incurred an average of 32 days of inpatient hospitalization and 10 outpatient care days. Postoperative treatment included long-term chronic biliary intubation averaging 378 days. Two patients (4%) died as a result of their LC-related complications. Patients with bile duct injuries that were recognized immediately at the time of the initial surgery ultimately experienced a total cost for their repair and hospitalization of 43% to 83% less than for patients in whom recognition of the injury was delayed (p < 0.019 to 0.070). In addition, the total hospitalization and outpatient care days was reduced by as much as 76% with early recognition of an iatrogenic injury. CONCLUSIONS: Repair of cholecystectomy-related bile duct injuries can run 4.5 to 26.0 times the cost of the uncomplicated procedure and carries a significant mortality rate. Intraoperative recognition of such an injury with immediate conversion to an open procedure for definitive repair can result in significant cost savings and relates directly to a decreased morbidity, mortality, length of hospitalization, and number of outpatient care days.

Adult↗
PubMed1996

Peanut bud necrosis tospovirus S RNA: complete nucleotide sequence, genome organization and homology to other tospoviruses.

The complete nucleotide sequence of the S RNA of peanut bud necrosis virus (PBNV) has been determined. The RNA is 3 057 nucleotides in length, contains inverted repeats and two open reading frames (ORFs) with an ambisense coding strategy that are separated by an A+U-rich intergenic region. One ORF (1 320 nucleotides in the viral sense strand) encodes a Mr 49.5 kDa protein, identified as the nonstructural (NSs) protein based on similarity to published tospovirus sequences. The second ORF (831 nucleotides in virus complementary strand) encodes a Mr 30.6 kDa protein. This protein was identified as the nucleocapsid (N) protein based on sequence similarities. Amino acid sequence comparison of N and NSs proteins revealed identities of 22-34% with the reported tospovirus isolates of serogroups I, II, and III, whereas it had 82-86% identity with viruses in serogroup IV, watermelon silver mottle virus (WSMV) and tomato isolate of peanut bud necrosis (PBNV-To). Two subgenomic RNA species detected in PBNV infected tissue corresponded to the predicted sizes (1.65 and 1.4 kb) of the NSs and N mRNAs. The data presented show conclusively that PBNV should be included in serogroup IV, along with WSMV and PBNV-To.

Amino Acid Sequence↗
PubMed1996

Polymerase chain reaction for detecting Escherichia coli O157: H7.

Escherichia coli O157:H7 is known as an important cause of hemorrhagic colitis and hemolytic uremic syndrome. Real-time procedures that are sensitive for detecting small populations of this bacterium in food are lacking and needed. An expression library was constructed by ligation of BamHI-EcoRI DNA fragments of E. coli O157:H7 to plasmid vector pUC19 and transformation of recombinant plasmids to E. coli JM109. A clone that contained a specific DNA fragment of E. coli O157:H7 was identified by colony immunoblot assay using monoclonal antibody MAb 4E8C12 that uniquely links to E. coli O157:H7 and a few other serotypes of verotoxin-producing E. coli. The DNA sequence of the clone consisted of 110 bp of 5' region of enterohemorrhagic E. coli (EHEC) eae gene and a 688 bp DNA fragment adjacent to 5' end of the eae gene, including an unknown function gene encoding 156 amino acids. A pair of oligonucleotide primers was synthesized based on the sequence of the 688 bp fragment. The primers were used in a polymerase chain reaction (PCR) to amplify a target DNA of 633 bp. The primers amplified 1 ng of DNA from 67 strains of E. coli O157:H7, two strains of E. coli O157:NM, and 7 of 11 E. coli O55:H7 and O55:NM strains, but not 50 ng of DNA from 34 strains of 29 other E. coli serotypes and 25 strains of 8 other bacterial species. Annealing temperatures from 60 to 63 degrees C could be used for the PCR without loss of specificity. The minimum amount of target DNA detected by the PCR was 5 pg. When a boiling method and GeneReleaser were used, the PCR was able to detect as few as 25 and 38 CFU of E. coli O157:H7, respectively, in 3 h.

Antibodies, Monoclonal↗
PubMed1996

The complete nucleotide sequence and genome organization of the M RNA segment of peanut bud necrosis tospovirus and comparison with other tospoviruses.

The M RNA of peanut bud necrosis virus (PBNV; synonym groundnut bud necrosis virus) is 4801 nucleotides in length. It comprised two ORFs in an ambisense organization and terminal inverted repeats. The 3' large ORF (3363 nucleotides in the virus-complementary strand) encoded a protein with a predicted size of 127.2 kDa which was identified as the glycoprotein precursor (GP) of the G1 and G2 glycoproteins. A comparison of the deduced amino acid sequence of GP revealed 37% identity and 58-59% similarity with that of tomato spotted wilt virus (TSWV, serogroup I) and impatiens necrotic spot virus (INSV, serogroup III), and 21-23% identity and 44-47% similarity with those of other members of the genus Bunyavirus. The 5' small ORF (924 nucleotides in the virussense strand) encoded a 34.2 kDa protein which was identified as the non-structural (NSm) protein based on 41-43% identity and 60-63% similarity with that of TSWV and INSV. Defective RNA molecules derived from the genomic M RNA were detected during continuous passage of the virus by sap inoculations.

Amino Acid Sequence↗
PubMed1996

Outcome of tunneled hemodialysis catheters placed by radiologists.

PURPOSE: To compare the outcomes of hemodialysis catheters placed by interventional radiologists with those placed by surgeons. MATERIALS AND METHODS: The outcomes were retrospectively analyzed of 237 hemodialysis catheters placed in 140 patients by a radiology service from January 1991 through December 1992. Follow-up data were available for 222 catheters (94%). Catheter secondary patency and freedom from infection were analyzed statistically and by means of life-table analysis. RESULTS: Pneumothorax occurred after the placement of six catheters (2.5%); in two patients, a chest tube was required for decompression. Other short-term complications included air embolism with no clinical sequelae (two procedures) and prolonged oozing from the tunnel (two procedures). Long-term complications included infection and catheter failure. Infection occurred in 26 patients (18%) with 32 catheters (14%) and resulted in removal of 25 catheters. Ninety-three catheters (42%) failed, and 63 catheters (28%) were removed because of failure. CONCLUSION: Hemodialysis catheters placed by radiologists do not have a higher rate of complications or failure than catheters placed by surgeons.

Case-Control Studies↗
PubMed1995

Cloning and nucleotide sequence of a gene upstream of the eaeA gene of enterohemorrhagic Escherichia coli O157:H7.

A DNA segment located immediately upstream of the eaeA gene of enterohemorrhagic Escherichia coli O157:H7 strain HA1 was cloned and sequenced. This segment contained an open reading frame encoding a predicted protein of 156 amino acids. A database search identified similar open reading frames upstream of the eaeA gene in two other bacterial pathogens, i.e. enteropathogenic E. coli and Citrobacter freundii. The predicted amino acid sequence of the enterohemorrhagic E. coli protein shared 96.8% and 94.2% identity with the enteropathogenic E. coli and C. freundii sequences, respectively. Because the open reading frame is located within the locus of enterocyte effacement region of the E. coli chromosome, a 'hot spot' for insertion of virulence factor genes, and shares high sequence homology with attaching and effacing EPEC and C. freundii, this protein may be associated with pathogenicity of E. coli O157:H7.

Amino Acid Sequence↗
PubMed1993

The mitochondrial genome of Anopheles quadrimaculatus species A: complete nucleotide sequence and gene organization.

The complete sequence (15,455 bp) of the mitochondrial DNA of the mosquito Anopheles quadrimaculatus species A is reported. This genome is compact and very A+T rich (77.4% A+T). It contains genes for 2 ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), and 13 subunits of the mitochondrial inner membrane respiratory complexes. The gene arrangement is the same as in Drosophila yakuba, except that the positions of two contiguous tRNAs are reversed and a third tRNA is transcribed from the complementary strand. Protein-coding genes, rRNAs, and most tRNAs were similar to D. yakuba. Two tRNAs had nonstandard secondary structures comparable with those of nematode mitochondrial tRNAs. The very small putative control region (625 bp) contains no sequence motifs similar to those used in vertebrates and other insects for initiation of transcription and replication.

Amino Acid Sequence↗
PubMed1993

Multiple-technique identification of sibling species of the Anopheles quadrimaculatus complex.

In the past, most researchers used a single technique for identification of cryptic taxa, population structures, biosystematics, and phylogenetic studies. Our experience with the Anopheles quadrimaculatus complex shows the importance of using several methods on individual mosquitoes. This approach consists of analysis of the polytene chromosomes in ovarian nurse cells, gas chromatographic profiles of cuticular hydrocarbons, isozyme electrophoresis, and restriction site analysis of mitochondrial or genomic DNA. We recommend use of this multiple-technique approach when analyzing feral populations for the first time, or for correlating information obtained by investigators using different techniques.

Animals↗
PubMed1992

Segmental renal artery embolization for treatment of pediatric renovascular hypertension.

Selective intrarenal arterial embolization was used to treat three children with documented renovascular hypertension. Embolization resulted in complete cure (ie, elimination of all antihypertensive medicines) in all three patients and caused only minimal loss of renal parenchyma. Renal vein renin sampling, including sampling after furosemide administration, correlated well with the location of identified vascular lesions and helped direct selective angiography when lesions were not found initially. Intrarenal arterial embolization is a safe, effective alternative to surgical resection in the treatment of renovascular hypertension in children who have identifiable intrarenal arterial lesions not amenable to balloon angioplasty.

Child↗
PubMed1992

Mitochondrial and ribosomal DNA variation among members of the Anopheles quadrimaculatus (Diptera: Culicidae) species complex.

The extent of intra- and inter-specific variation in mitochondrial DNA and nuclear ribosomal RNA gene restriction sites was determined for the four sibling species of the Anopheles quadrimaculatus complex. Individual mosquitoes were identified by allozyme analysis according to previously published keys, and the total genomic DNA of these same individuals was then cleaved with restriction enzymes. Restriction maps of mitochondrial DNA, including the positions of variable sites, were constructed for each species. No evidence for interspecific hybridization was found in the populations surveyed. There was little variation in restriction patterns within any given species, but differences occurred among the four. Three restriction enzymes (AvaI, HindIII, and PvuII) yielded species-specific DNA restriction patterns for the mitochondrial DNA, while AvaI and HindIII produced diagnostic patterns for the ribosomal DNA. Thus, restriction patterns were very useful for detecting cryptic species but less appropriate than isozymes for studying genetic structure of populations within species.

Animals↗
PubMed1991

Choledochal cysts: role of noninvasive imaging, percutaneous transhepatic cholangiography, and percutaneous biliary drainage in diagnosis and treatment.

Choledochal cysts are an uncommon anomaly of the biliary system; findings include cystic dilatation of the extrahepatic biliary tree, intrahepatic biliary tree, or both. In the past 7 years, 13 patients with choledochal cysts have been seen at the authors' institution for evaluation and presurgical intervention. Percutaneous transhepatic cholangiography (PTC) was performed in 13 patients. Sixteen percutaneous biliary drainage (PBD) procedures were performed in 11 patients, computed tomography was performed in six patients, and ultrasound was performed in two. PTC proved to be an important imaging modality because of its superior ability to define the cyst anatomy, site of biliary origin of the cyst, and extent and detail of both extrahepatic and intrahepatic disease, that is, intraductal strictures and calculi. PBD proved valuable in preoperative intervention, as an aid in surgical reconstruction, and in postoperative care. The role of these two modalities in the diagnosis and treatment of patients with choledochal cysts, in addition to clinical aspects of the disease, is discussed.

Adult↗
PubMed1991

Concurrent radiotherapy and chemotherapy for locally advanced non-small-cell cancer of the lung. Report of a clinical trial and review of the literature.

A prospective nonrandomized phase II study was begun in 1985 using concurrent split-course radiation and chemotherapy in the treatment of locally advanced non-small-cell cancer of the lung. Patients were treated with 3,000 cGy of radiation in 15 fractions to the chest, together with 100 mg/m2 cisplatin on day 1 and 1,000 mg/m2/day 5-fluorouracil infusion on days 1-4. The radiation and chemotherapy were then repeated after a 1-week break. Twenty-one patients were treated, with five patients having a complete response and nine patients having a partial response for an overall response rate of 67%. With a minimum of 24 months follow-up, five patients remain alive. Median survival for the entire group is 11.6 months. The toxicity of the treatment regimen was acceptable. These results do not differ significantly from survivals of similar patients treated with radiation alone, including a series from our own institution. The literature on concurrent chemotherapy and radiation is reviewed and possible future approaches to this tumor are discussed.

Adult↗
PubMed1991

Endoscopy as an adjuvant to biliary radiologic intervention.

Twenty-two patients underwent 24 percutaneous biliary procedures guided with choledochoscopy, an adjunctive percutaneous biliary technique. All but four procedures were performed through established percutaneous tracts; the others, through tracts less than 4 weeks old. The procedures were done for the following reasons: removal of calculi (n = 15), electrohydraulic lithotripsy (n = 1), biliary duct biopsies (n = 8), cauterization of a bleeding tract (n = 1), and evaluation of biliary-enteric anastomoses (n = 11). The only complication was one case of severe nausea after choledochoscopy. This patient required overnight hospitalization and medical treatment. All procedures were technically successful, except one case in which the tract was undersized. All patients received intravenously administered antibiotics before and after the procedure. It is concluded that choledochoscopy is a safe, atraumatic, and well-tolerated method of evaluating and treating biliary disease and that it markedly reduces radiation exposure. It can be performed rapidly with minimal sedation on an in- or outpatient basis.

Adult↗
PubMed1991

Choledochal cysts: classification and cholangiographic appearance.

A classification scheme for choledochal cysts is outlined and their appearance on cholangiograms is illustrated. Choledochal cysts are uncommon anomalies of the biliary system and are probably congenital in origin. They are manifested by cystic dilatation of the extra- or intrahepatic biliary tree or both. The classification system described here divides choledochal cysts into one of five main types. The most common, which is manifested by cystic or focal segmental dilatation of the common bile duct or fusiform choledochal dilatation, accounts for 80-90% of cases.

Cholangiography↗