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J Coleman

Publications and source records attributed to J Coleman.

At least 73 records · Page 4Linked to original sources
PubMed1997

Six hundred fifty consecutive pancreaticoduodenectomies in the 1990s: pathology, complications, and outcomes.

OBJECTIVE: The authors reviewed the pathology, complications, and outcomes in a consecutive group of 650 patients undergoing pancreaticoduodenectomy in the 1990s. SUMMARY BACKGROUND DATA: Pancreaticoduodenectomy has been used increasingly in recent years to resect a variety of malignant and benign diseases of the pancreas and periampullary region. METHODS: Between January 1990 and July 1996, inclusive, 650 patients underwent pancreaticoduodenal resection at The Johns Hopkins Hospital. Data were recorded prospectively on all patients. All pathology specimens were reviewed and categorized. Statistical analyses were performed using both univariate and multivariate models. RESULTS: The patients had a mean age of 63 +/- 12.8 years, with 54% male and 91% white. The number of resections per year rose from 60 in 1990 to 161 in 1995. Pathologic examination results showed pancreatic cancer (n = 282; 43%), ampullary cancer (n = 70; 11%), distal common bile duct cancer (n = 65; 10%), duodenal cancer (n = 26; 4%), chronic pancreatitis (n = 71; 11%), neuroendocrine tumor (n = 31; 5%), periampullary adenoma (n = 21; 3%), cystadenocarcinoma (n = 14; 2%), cystadenoma (n = 25; 4%), and other (n = 45; 7%). The surgical procedure involved pylorus preservation in 82%, partial pancreatectomy in 95%, and portal or superior mesenteric venous resection in 4%. Pancreatic-enteric reconstruction, when appropriate, was via pancreaticojejunostomy in 71% and pancreaticogastrostomy in 29%. The median intraoperative blood loss was 625 mL, median units of red cells transfused was zero, and the median operative time was 7 hours. During this period, 190 consecutive pancreaticoduodenectomies were performed without a mortality. Nine deaths occurred in-hospital or within 30 days of operation (1.4% operative mortality). The postoperative complication rate was 41%, with the most common complications being early delayed gastric emptying (19%), pancreatic fistula (14%), and wound infection (10%). Twenty-three patients required reoperation in the immediate postoperative period (3.5%), most commonly for bleeding, abscess, or dehiscence. The median postoperative length of stay was 13 days. A multivariate analysis of the 443 patients with periampullary adenocarcinoma indicated that the most powerful independent predictors favoring long-term survival included a pathologic diagnosis of duodenal adenocarcinoma, tumor diameter <3 cm, negative resection margins, absence of lymph node metastases, well-differentiated histology, and no reoperation. CONCLUSIONS: This single institution, high-volume experience indicates that pancreaticoduodenectomy can be performed safely for a variety of malignant and benign disorders of the pancreas and periampullary region. Overall survival is determined largely by the pathology within the resection specimen.

Adenocarcinoma↗
PubMed1997

Acquired immunodeficiency syndrome in Alabama: special concerns for black women.

BACKGROUND: Among AIDS case reports from rural and small town areas of the United States, rates are higher in the South than in any other part of the country. METHODS: For this study, we analyzed AIDS surveillance statistics from the state of Alabama for trends, distributions, and populations affected. We aggregated Alabama AIDS surveillance data in 5-year intervals--1981 to 1985, 1986 to 1990, 1991 to 1995--and made comparisons based on geographic area of residence of people diagnosed with AIDS. RESULTS: Of the 3,558 cases of AIDS reported in Alabama in the period 1981 to 1995, 86% were men and 14% were women. Among women, 69.7% were black and 29.1% were white. Among men, 48.4% were black and 50.9% were white. We compared these figures with 1995 Alabama population estimates of 26.2% black, 73.7% white, and < 1% another race. The rates for black women and white women increased 170-fold and 23-fold, respectively, from the 1981 to 1985 period to the 1991 to 1995 period. For the same periods, case rates for black men and white men increased more than 80-fold and 50-fold, respectively. Black women showed a rise per 100,000 population-from 0.3 (1981 to 1985) in both northern and southern Alabama to 37 in northern Alabama and 64 in southern Alabama (1991 to 1995). CONCLUSIONS: Black women are at disproportionately high risk, particularly in the southern counties of Alabama. HIV is increasingly prevalent in rural and small town communities in Alabama and is more often transmitted heterosexually than it has been previously.

Acquired Immunodeficiency Syndrome↗
PubMed1997

TeleInViVo: a collaborative volume visualization application.

Converging technologies in the areas of networks, volume visualization algorithms, and computer performance have made possible the development of a new tool for collaboration, which extends the reach of health professionals, and other consumers of volumetric data around the world. TeleInViVo(tm) is a three-dimensional (3D) collaborative volume visualization tool for medical applications. It extends the capabilities of InViVo(tm), a fast volume visualization tool developed at the Fraunhofer IGD, Darmstadt, Germany [1-3], with efficient and intuitive network collaboration features for remote consultation and new modes of interaction. The software runs on both UNIX and Windows NT platforms. TeleInViVo provides a high degree of interactivity for the medical professional when interacting with the patient data, facilitates explanation and communication between field personnel and medical experts located far from the field, and permits viewing of the data in a multitude of ways designed to support rapid and accurate diagnosis. Current efforts involve architectural enhancements to support multiuser, distributed telemedical scenarios. The application includes the following features: Volume and subvolume data transmission at user specified resolution, Synchronization cues, Integration of Immersion Probe(tm), a 6 degree-of-freedom input device, for ergonomic 3D data exploration, Tools for measuring distances, Tools for planning instrument path, Arbitrary cutting planes in real time, Interactive segmentation tools, Virtual video recorder and playback (cine loops), 3D stereo mode. TeleInViVo is an essential part of the MUSTPAC-1 portable 3D ultrasound system developed by Battelle Pacific Northwest Labs, Richland, WA.

Computer Communication Networks↗
PubMed1996

Biliary carcinoembryonic antigen levels are a marker for cholangiocarcinoma.

BACKGROUND: Cholangiocarcinoma develops in 5% to 15% of patients with choledochal cysts, sclerosing cholangitis, and intrahepatic stones. The detection of cholangiocarcinoma in patients with premalignant biliary conditions has been difficult. Serum levels of carcinoembryonic antigen (CEA) have been neither sensitive nor specific for the diagnosis of cholangiocarcinoma. However, CEA has been shown to be present in cholangiocarcinomas by immunohistochemical staining. Therefore, we measured the level of CEA excreted in bile in patients with benign strictures, premalignant biliary diseases, and cholangiocarcinoma. PATIENTS AND METHODS: Bile was obtained from transhepatic stents in patients with benign biliary strictures (34), choledochal cysts (5), primary sclerosing cholangitis (6), intrahepatic cholelithiasis (5), and perihilar cholangiocarcinoma (25). Samples were analyzed for CEA using a solid phase, two-site immunoenzymetric assay. RESULTS: Biliary CEA levels were significantly elevated (P < 0.01) in patients with cholangiocarcinoma (50.2 +/- 5.8 ng/mL) and intrahepatic cholelithiasis (57.4 +/- 10.4 ng/mL) compared with patients with benign strictures (10.1 +/- 3.9 ng/mL). Patients with sclerosing cholangitis (21.6 +/- 3.9 ng/mL) and choledochal cysts (20.0 +/- 16.5 ng/mL) had intermediate levels. In 5 patients undergoing resection of perihilar cholangiocarcinomas, the mean biliary CEA level decreased from a preoperative level of 46.8 +/- 6.7 ng/mL to a postoperative level of 11.3 +/- 5.6 ng/mL (P < 0.02). In 4 patients with progression of cholangiocarcinoma, biliary CEA increased from a mean of 53.3 +/- 6.9 ng/mL to 98.3 +/- 12.2 ng/mL (P < 0.02) over a mean interval of 9.5 months. CONCLUSIONS: Increased levels of CEA can be detected in the bile of patients with chlolangiocarcinoma. Monitoring these levels may have a role in the management of cholangiocarcinoma as well as premalignant biliary conditions such as choledochal cysts and sclerosing cholangitis.

Adult↗
PubMed1996

Cholangiocarcinoma. A spectrum of intrahepatic, perihilar, and distal tumors.

OBJECTIVE: The objective of this article is to introduce a simple method for classifying cholangiocarcinomas and to apply this system to analyze a large number of patients from a single institution. SUMMARY BACKGROUND DATA: For the past 2 decades, most western reports on cholangiocarcinoma have separated intrahepatic from extrahepatic tumors and have subclassified this latter group into proximal, middle, and distal subgroups. However, "middle" lesions are uncommon and are managed most often either with hilar resection or with pancreatoduodenectomy. The spectrum of cholangiocarcinoma, therefore, is best classified into three broad groups: 1) intrahepatic, 2) perihilar, and 3) distal tumors. These categories correlate with anatomic distribution and imply preferred treatment. METHODS: The records of all patients with histologically confirmed cholangiocarcinoma who underwent surgical exploration at The Johns Hopkins Hospital over a 23-year period were reviewed. RESULTS: Of 294 patients with cholangiocarcinoma, 18 (6%) had intrahepatic, 196 (67%) had perihilar, and 80 (27%) had distal tumors. Age, gender, race, and associated diseases were similar among the three groups. Patients with intrahepatic tumors, by definition, were less likely (p < 0.01) to be jaundiced and more likely (p < 0.05) to present with abdominal pain. The resectability rate increased with a more distal location (50% vs. 56% vs. 91%), and resection improved survival at each site. Five-year survival rates for resected intrahepatic, perihilar, and distal tumors were 44%, 11%, and 28%, and median survival rates were 26, 19, and 22 months, respectively. Postoperative radiation therapy did not improve survival. In a multivariate analysis resection (p < 0.001. hazard ratio 2.80), negative microscopic margins (p < 0.01, hazard ratio 1.79), preoperative serum albumin (p < 0.04, hazard ratio 0.82), and postoperative sepsis (p < 0.001, hard ratio 0.27) were the best predictors of outcome. CONCLUSIONS: Cholangiocarcinoma is best classified into three broad categories. Resection remains the primary treatment, whereas postoperative adjuvant radiation has no influence on survival. Therefore, new agents or strategies to deliver adjuvant therapy are needed to improve survival.

Bile Duct Neoplasms↗
PubMed1996

Confirmation of Borrelia burgdorferi spirochetes by polymerase chain reaction in placentas of women with reactive serology for Lyme antibodies.

The purpose of our study was to determine whether Borrelia burgdorferi spirochetes were present in placentas of asymptomatic women with reactive Lyme serology using a silver stain, and to confirm the identity of the spirochetes by polymerase chain reaction (PCR). Sixty placentas of asymptomatic women with ELISA-positive or-equivocal serology for Lyme antibodies during pregnancy were examined for spirochetes using a silver stain. The results of the ELISA serology were confirmed by Western blot analysis. PCR amplification for B. burgdorferi was performed on placentas identified to have spirochetes and on a group of placentas negative for spirochetes. Spirochetes were identified by silver staining in 3 (5%) of the 60 placentas. PCR confirmed B. burgdorferi nucleotide sequences in 2 of the placentas. The 5 women had equivocal Lyme ELISA and negative syphilis serology. The results of the Western blot analysis were negative in 2 cases and indeterminate in 1 case. Six controls were negative for spirochetes by silver staining and PCR. A normal perinatal outcome was observed in all cases. Spirochetes identified in placental tissue of pregnancies with reactive Lyme serology were confirmed by PCR to be B. burgdorferi. There was no relationship between the presence of placental spirochetes and the results of Lyme serology or the pregnancy outcome.

Blotting, Western↗
PubMed1996

Elements of the employee selection process: interviewing operating room staff.

Selecting the right staff for employment in an operating room (OR) is critical to the success of any OR manager. Legal considerations limit the ability to gather certain information. However, by applying the correct skills and techniques, the manager can develop an information base that will lead to better decisions when selecting employees who can contribute to an efficiently run department.

Humans↗
PubMed1995

A plant acyltransferase involved in triacylglycerol biosynthesis complements an Escherichia coli sn-1-acylglycerol-3-phosphate acyltransferase mutant.

The second acylation reaction in glycerolipid biosynthesis is catalyzed by an sn-1-acylglycerol-3-phosphate acyltransferase. The enzyme of Limnanthes douglasii involved in triacylglycerol synthesis has an unusual specificity for very long chain acyl groups in both of its substrates, namely acyl-CoA and sn-1-acylglycerol-3-phosphate, and causes the enrichment of erucoyl groups in the sn-2 position of the seed oil of this plant species. We have isolated a cDNA clone encoding this embryo-specific, microsomal acyltransferase via heterologous complementation of an Escherichia coli mutant deficient in sn-1-acylglycerol-3-phosphate acyltransferase activity. The open reading frame of the cDNA insert encodes a protein with a length of 281 amino acids, with three predicted membrane-spanning domains and of about 31.7 kDa. The sequence exhibits substantial sequence similarity to the sn-1-acylglycerol-3-phosphate acyltransferase of E. coli. The corresponding transcript was detectable in developing embryos but not in leaves of L. douglasii, and expression of the open reading frame in E. coli caused sn-1-acylglycerol-3-phosphate acyltransferase activity which showed properties different from those of the bacterial acyltransferase but typical of the L. douglasii enzyme involved in triacylglycerol biosynthesis.

1-Acylglycerol-3-Phosphate O-Acyltransferase↗
PubMed1995

Further characterization of the putative 5-HT4 receptor mediating depolarization of the rat isolated vagus nerve.

A putative 5-HT4 receptor-mediated depolarization of the rat isolated vagus nerve has been studied using a grease-gap extracellular recording technique. Ondansetron (1 microM) was used to block the predominant 5-HT3 receptor mediated depolarization in this preparation and the effects of the 5-HT4 receptor antagonists DAU 6285 (endo-8-methyl-8-azabicyclo [3.2.1] oct-3-yl-2,3-dihydro-6-methoxy-2-oxo-1H-benzimidazole-1- carboxylate HCl); 0.3, 1.0 or 3.0 microM and SDZ 205-557 (2-methoxy-4-amino-5-chloro-benzoic acid 2-(diethylamino)-ethyl ester HCl); 0.1, 0.3 or 1.0 microM were studied on the residual, ondansetron-resistant, component of the response. The effects of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX) and of forskolin on the ondansetron-resistant response were also studied. Both DAU 6285 and SDZ 205-557 acted as competitive antagonists of the ondansetron-resistant response to 5-HT with pA2 values of 6.8 (6.7-7.1, n = 12) and 7.1 (6.9-7.5, n = 12) respectively. The vagus nerve was depolarized by IBMX (100 microM) or forskolin (10 microM), the effects being similar to the maximum response to 5-HT. In the presence of IBMX (100 microM) or forskolin (10 microM) the ondansetron-resistant component of the response to 5-HT was enhanced and the 5-HT3 receptor-mediated component reduced. These results with DAU 6285 and SDZ 205-557 are consistent with a 5-HT4 receptor-mediated mechanism of the ondansetron-resistant depolarizing response to 5-HT.

4-Aminobenzoic Acid↗
PubMed1995

Pancreaticoduodenectomy for cancer of the head of the pancreas. 201 patients.

OBJECTIVE: This single-institution study examined the outcome after pancreaticoduodenectomy in patients with adenocarcinoma of the head of the pancreas. SUMMARY OF BACKGROUND DATA: In recent years, pancreaticoduodenectomy for adenocarcinoma of the head of the pancreas has been associated with decreased morbidity and mortality and, in some centers, 5-year survival rates in excess of 20%. METHODS: Two hundred one patients with pathologically verified adenocarcinoma of the head of the pancreas undergoing pancreaticoduodenectomy at The Johns Hopkins Hospital between 1970 and 1994 were analyzed (the last 100 resections were performed between March 1991 and April 1994). This is the largest single-institution experience reported to date. RESULTS: The overall postoperative in-hospital mortality rate was 5%, but has been 0.7% for the last 149 patients. The actuarial 5-year survival for all 201 patients was 21%, with a median survival of 15.5 months. There were 11 5-year survivors. Patients resected with negative margins (curative resections: n = 143) had an actuarial 5-year survival rate of 26%, with a median survival of 18 months, whereas those with positive margins (palliative resections; n = 58) fared significantly worse, with an actuarial 5-year survival rate of 8% and a median survival of 10 months (p < 0.0001). Survival has improved significantly from decade to decade (p < 0.002), with the 3-year actuarial survival of 14% in the 1970s, 21% in the 1980s, and 36% in the 1990s. Factors significantly favoring long-term survival by univariate analyses included tumor diameter < 3 cm, negative nodal status, diploid tumor DNA content, tumor S phase fraction < 18%, pylorus-preserving resection, < 800 mL intraoperative blood loss, < 2 units of blood transfused, negative resection margins, and use of postoperative adjuvant chemotherapy and radiation therapy. Multivariate analyses indicated the strongest predictors of long-term survival were diploid tumor DNA content, tumor diameter < 3 cm, negative nodal status, negative resection margins, and decade of resection. CONCLUSIONS: The survival of patients with pancreatic adenocarcinoma treated by pancreaticoduodenectomy is improving. Aspects of tumor biology, such as DNA content, tumor diameter, nodal status and margin status, are the strongest predictors of outcome.

Actuarial Analysis↗
PubMed1995

Perihilar cholangiocarcinoma. Postoperative radiotherapy does not improve survival.

OBJECTIVE: The aims of this analysis were to determine prospectively the effects of surgical resection and radiation therapy on the length and quality of survival as well as late toxicity in patients with perihilar cholangiocarcinoma. BACKGROUND: Retrospective analyses have suggested that adjuvant radiation therapy improves survival in patients with perihilar cholangiocarcinoma. However, in these reports, patients receiving radiotherapy tended to have smaller, often resectable tumors, and were relatively fit. In comparison, patients who have not received radiotherapy often had unresectable tumors, metastatic disease, or poor performance status. METHODS: From 1988 through 1993, surgically staged patients with perihilar cholangiocarcinoma and 1) no evidence of metastatic disease, 2) Karnofsky score > 60, 3) no prior malignancy or radiotherapy, and 4) a patent main portal vein were analyzed. Fifty patients were stratified by resection (n = 31) versus operative palliation (n = 19) and by radiation (n = 23) versus no radiotherapy (n = 27). RESULTS: Patients undergoing resection had smaller tumors (1.9 +/- 2.8 vs. 2.4 +/- 2.1 cm, p < 0.01) that were less likely to invade the hepatic artery (3% vs. 42%, p < 0.05) or portal vein (6% vs. 53%, p < 0.05). Multiple parameters that might have affected outcome were similar between patients who did and did not receive radiation therapy. Resection improved the length (24.2 +/- 2.5 vs. 11.3 +/- 1.0 months, p < 0.05) and quality of survival. Radiation had no effect on the length (18.4 +/- 2.9 vs. 20.1 +/- 2.4 months) or quality of survival or on late toxicity. CONCLUSIONS: This analysis suggests that in patients with localized perihilar cholangiocarcinoma, resection prolongs survival whereas radiation has no effect on either survival or late toxicity. Thus, new agents or strategies to deliver adjuvant therapy are needed to improve survival in these patients.

Bile Duct Neoplasms↗
PubMed1995

Interleukin-4 and interferon-gamma production in atopic and non-atopic children with asthma.

Previous studies have demonstrated increased production of interleukin-4 (IL-4) and reduced production of interferon (IFN)-gamma in stimulated peripheral blood mononuclear cell cultures from children and adults with atopic dermatitis, however, it is unclear whether such an imbalance of cytokine production relates to other childhood atopic diseases such as asthma, and in particular to the presence of the atopic state per se. The production of IL-4 and IFN gamma in phytohaemagglutin- (PHA)-stimulated peripheral blood mononuclear cell (PBMC) cultures from atopic and non-atopic children with moderately severe chronic persistent asthma, and a group of age-matched non-atopic controls who did not have asthma was examined. Atopic children with asthma produced significantly more IL-4 and less IFN gamma than non-atopic children with asthma and non-atopic controls who did not have asthma. There was no significant difference in IL-4 or IFN gamma production between non-atopic children with asthma and controls. These findings demonstrate that an imbalance of IL-4 and IFN gamma production is present in atopic asthma as previously documented in atopic dermatitis, therefore suggesting that it is a feature of the atopic state per se.

Asthma↗
PubMed1995

Membrane glycerophospholipid biosynthesis in Neisseria meningitidis and Neisseria gonorrhoeae: identification, characterization, and mutagenesis of a lysophosphatidic acid acyltransferase.

Lysophosphatidic acid (LPA) acyltransferases of Neisseria meningitidis and Neisseria gonorrhoeae were identified which share homology with other prokaryotic and eukaryotic LPA acyltransferases. In Escherichia coli, the conversion of LPA to phosphatidic acid, performed by the 1-acyl-sn-glycerol-3-phosphate acyltransferase PlsC, is a critical intermediate step in the biosynthesis of membrane glycerophospholipids. A Tn916-generated mutant of a serogroup B meningococcal strain was identified that exhibited increased amounts of capsular polysaccharide, as shown by colony immunoblots, and a threefold increase in the number of assembled pili. The single, truncated 3.8 kb Tn916 insertion in the meningococcal mutant was localized within a 771 bp open reading frame, The gonococcal equivalent of this gene was identified by transformation with the cloned meningococcal mutant gene. In N. gonorrhoeae, the mutation increased piliation fivefold. The insertions were found to be within a gene that was subsequently designated nlaA (neisserial LPA acyltransferase). The predicted neisserial LPA acyltransferases were homologous (>20% identity, >40% amino acid similarity) to the family of PlsC protein homologues. A cloned copy of the meningococcal nlaA gene complemented in trans a temperature-sensitive E. coli PlsCts- mutant. Tn916 and omega-cassette insertional inactivations of the neisserial nlaA genes altered the membrane glycerophospholipid compositions of both N. meningitidis and N. gonorrhoeae but were not lethal. Therefore, the pathogenic Neisseria spp. appear to be able to utilize alternative enzyme(s) to produce phosphatidic acid. This hypothesis is supported by the observation that, although the amounts of mature glycerophospholipids were altered in the meningococcal and the gonococcal nlaA mutants, glycerophospholipid synthesis was detectable at significant levels. In addition, acyltransferase enzymatic activity, while reduced in the gonococcal nlaA mutant, was increased in the meningococcal nlaA mutant. We postulate that the pathogenic Neisseria spp. are able to utilize alternate acyltransferases to produce glycerophospholipids in the absence of nlaA enzymatic activity. Implementation of these secondary enzymes results in alterations of glycerophospholipid composition that lead to pleiotropic effects on the cell surface components, including effects on capsule and piliation.

Acyltransferases↗
PubMed1995

The enantiomers of zacopride: an intra-species comparison of their potencies in functional and anxiolytic models.

1. The 5-HT3 receptor antagonist, zacopride, and its enantiomers, R(+)-zacopride and S(-)-zacopride, were examined in three pharmacological models: (i) 5-HT-induced depolarization of the mouse isolated vagus nerve preparation, (ii) the 5-HT-evoked von Bezold-Jarisch reflex in the mouse, and (iii) the mouse light:dark box model of anxiety. Other standard 5-HT3 receptor antagonists were also included for comparison in these studies. 2. Racemic zacopride, and both of the enantiomers, displayed potent 5-HT3 receptor antagonist activity in the isolated vagus nerve and in the von Bezold-Jarisch model. No 5-HT3 receptor agonist or partial agonist effects of these compounds were detected. 3. In the isolated vagus nerve, R(+)-zacopride and ondansetron were surmountable 5-HT3 receptor antagonists (pA2 values of 9.3 and 8.3, respectively), whereas racemic zacopride, S(-)-zacopride and tropisetron were insurmountable antagonists, markedly suppressing the maximum response to 5-HT. 4. In vivo, racemic zacopride, R(+)-zacopride, S(-)-zacopride and WAY100289 were potent antagonists of the 5-HT-evoked von Bezold-Jarisch reflex, with minimum effective doses (lowest dose required to reduce the reflex by > or = 85%; MED85) of 1.0, 3.0, 0.3 and 3.0 micrograms kg-1, s.c., respectively. 5. Racemic zacopride, R(+)-zacopride and S(-)-zacopride were active in the mouse light:dark box model of anxiety, with similar potencies (minimum effective dose 1 microgram kg-1, s.c.) and similar active dose-ranges (1-1000 micrograms kg-1, s.c.). 6. The doses of racemic zacopride, R( + )-zacopride and S(-)-zacopride required to block 5-HT3receptors in vivo correlated reasonably well with their potencies in an anxiety model within the same species. In these studies, there was no evidence of a marked difference between the anxiolytic potencies ofR( + )-zacopride and S(-)-zacopride.

Animals↗
PubMed1994

In vitro selection of small RNAs that bind to Escherichia coli phenylalanyl-tRNA synthetase.

Small RNAs were selected from a highly degenerate library on the basis of their ability to bind tightly to Escherichia coli phenylalanyl-tRNA synthetase (FRS). The 63 nucleotide library consisted of the acceptor stem and portions of the D and T stems of E. coli tRNA(Phe) flanking a 32 nucleotide randomized region. Because FRS binding relies on a correctly folded tRNA substrate, the selected variants from this library were expected to resemble tRNA(Phe) structure. After seven cycles of selection, the RNA library bound to FRS with similar affinity to that of the E. coli tRNA(Phe), but did not show detectable aminoacylation. Fourteen FRS-specific isolates were sequenced and found to contain an anticodon stem-loop including the anticodon triplet of tRNA(Phe). The tight-binding RNAs fell into two classes depending on the location of this step-loop within the sequence. The acceptor stem defined by the non-randomized sequence was also found to be essential for binding. Mutation of two residues within a common hexanucleotide sequence present in one of the classes reduced binding to FRS. Taken together, these results suggest that in order to bind RNAs tightly, FRS requires the simultaneous interaction of the anticodon stem-loop and acceptor stem, and additional sequences needed for proper folding. This approach should assist in the detection of motifs that resemble tRNA, but are too dissimilar to be identified by sequence comparison.

Base Sequence↗
PubMed1994

Virtual reality and laparoscopic surgery.

The nature of laparoscopic surgery makes it likely to benefit from current and future developments in virtual reality and telepresence technology. High-definition screens, three-dimensional sensory feedback and remote dextrous manipulation will be the next major developments in laparoscopic surgery. Simulators may be used in surgical training and in the evaluation of surgical capability.

Computer Simulation↗
PubMed1994

Isolation and characterisation of a maize cDNA that complements a 1-acyl sn-glycerol-3-phosphate acyltransferase mutant of Escherichia coli and encodes a protein which has similarities to other acyltransferases.

We selected cDNA plasmid clones that corrected the temperature-sensitive phenotype of Escherichia coli strain JC201, which is deficient in 1-acyl-sn-glycerol-3-phosphate acyltransferase activity. A plasmid-based maize endosperm cDNA library was used for complementation and a plasmid that enabled the cells to grow at 44 degrees C on ampicillin was isolated. Addition of this plasmid (pMAT1) to JC201 restored 1-acyl-sn-glycerol-3-phosphate acyltransferase activity to the cells. Total phospholipid labelling showed that the substrate for the enzyme, lysophosphatidic acid, accumulated in JC201 and was further metabolised to phosphatidylethanolamine in complemented cells. Membranes isolated from such cells were able to convert lysophosphatidic acid to phosphatidic acid in acyltransferase assays. The cDNA insert of pMAT1 contains one long open reading frame of 374 amino acids which encodes a protein of relative molecular weight 42,543. The sequence of this protein is most similar to SLC1, which is thought to be able to acylate glycerol at the sn-2 position during synthesis of inositol-containing lipids. Homologies between the SLC1 protein, the 1-acyl-sn-glycerol-3-phosphate acyltransferase of E. coli (PlsC) and the maize ORF were found with blocks of conserved amino acids, whose spacing was conserved between the three proteins, identifiable.

1-Acylglycerol-3-Phosphate O-Acyltransferase↗