Characterizing the surface quality and droplet interface shape for microarray plates.

The variation in the surface quality of microarray plates was examined by measuring the contact angles of 480 droplets on five microarray plates. It was found that the measured contact angle did not accurately predict the droplet shape for moderate Bond numbers (~0.5 ≤ N(B) ≤ 5). By defining an apparent contact angle using the ratio of the contact radius to the height, the variance in the predicted interface shape decreased by greater than a factor of 3 for both local and globally averaged characteristics. The error in the predicted droplet height was also reduced by 3 orders of magnitude.

An empirically validated analytical model of droplet dynamics in electrowetting on dielectric devices.

Explicit analytical models that describe the capillary force on confined droplets actuated in electrowetting on dielectric devices and the reduction in that force by contact angle hysteresis as a function of the three-dimensional shape of the droplet interface are presented. These models are used to develop an analytical model for the transient position and velocity of the droplet. An order of magnitude analysis showed that droplet motion could be modeled using the driving capillary force opposed by contact angle hysteresis, wall shear, and contact line friction. Droplet dynamics were found to be a function of gap height, droplet radius, surface tension, fluid density, the initial and deformed contact angles, contact angle hysteresis, and friction coefficients pertaining to viscous wall friction and contact line friction. The first four parameters describe the device geometry and fluid properties; the remaining parameters were determined experimentally. Images of the droplet during motion were used to determine the evolution of the shape, position, and velocity of the droplet with time. Comparisons between the measured and predicted results show that the proposed model provides good accuracy over a range of practical voltages and droplet aspect ratios.

SLX4 interacts with RTEL1 to prevent transcription-mediated DNA replication perturbations.

The SLX4 tumor suppressor is a scaffold that plays a pivotal role in several aspects of genome protection, including homologous recombination, interstrand DNA crosslink repair and the maintenance of common fragile sites and telomeres. Here, we unravel an unexpected direct interaction between SLX4 and the DNA helicase RTEL1, which, until now, were viewed as having independent and antagonistic functions. We identify cancer and Hoyeraal-Hreidarsson syndrome-associated mutations in SLX4 and RTEL1, respectively, that abolish SLX4-RTEL1 complex formation. We show that both proteins are recruited to nascent DNA, tightly co-localize with active RNA pol II, and that SLX4, in complex with RTEL1, promotes FANCD2/RNA pol II co-localization. Importantly, disrupting the SLX4-RTEL1 interaction leads to DNA replication defects in unstressed cells, which are rescued by inhibiting transcription. Our data demonstrate that SLX4 and RTEL1 interact to prevent replication-transcription conflicts and provide evidence that this is independent of the nuclease scaffold function of SLX4.

Publisher Correction: SLX4 interacts with RTEL1 to prevent transcription-mediated DNA replication perturbations.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Author Correction: SLX4 interacts with RTEL1 to prevent transcription-mediated DNA replication perturbations.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Extension of cell life-span and telomere length in animals cloned from senescent somatic cells.

The potential of cloning depends in part on whether the procedure can reverse cellular aging and restore somatic cells to a phenotypically youthful state. Here, we report the birth of six healthy cloned calves derived from populations of senescent donor somatic cells. Nuclear transfer extended the replicative life-span of senescent cells (zero to four population doublings remaining) to greater than 90 population doublings. Early population doubling level complementary DNA-1 (EPC-1, an age-dependent gene) expression in cells from the cloned animals was 3.5- to 5-fold higher than that in cells from age-matched (5 to 10 months old) controls. Southern blot and flow cytometric analyses indicated that the telomeres were also extended beyond those of newborn (<2 weeks old) and age-matched control animals. The ability to regenerate animals and cells may have important implications for medicine and the study of mammalian aging.

Factors associated with complications of open versus laparoscopic sigmoid resection for diverticulitis.

BACKGROUND: This study critically reviews sigmoid colon resection for diverticulitis comparing open and laparoscopic techniques. METHODS: We conducted a retrospective review of all open and laparoscopic cases of diverticulitis between 1992 and 2001. Data analyzed included the following: indications for operation, postoperative complications, and incidence of laparoscopic conversion to laparotomy. Major and minor complications were analyzed in relation to patients' preoperative diagnosis, age, presence or absence of splenic flexure mobilization, length of stay, and laparoscopic sigmoid resection versus open sigmoid resection. RESULTS: Over a 10-year period, 166 resections for diverticulitis were performed including 126 open cases and 40 laparoscopic cases. No significant differences existed in patient characteristics between the groups. Major complications occurred in 14% of patients, and the laparoscopic conversion rate was 20%. The presence of abscess, fistula, or stricture preoperatively was associated with a higher complication rate only in patients > or =50 years old undergoing open sigmoid resection. The length of stay between patients undergoing laparoscopic resection was significantly less than in patients having open resection. CONCLUSION: Advanced laparoscopic sigmoid resection is an alternative to open sigmoid resection in patients with diverticulitis and its complications. Open sigmoid resection in patients >50 years may have a higher complication rate in complicated diverticulitis when compared with laparoscopic sigmoid resection (all patient ages) and open sigmoid resection (patients <50 years old). Regarding complications, no difference existed between the length of stay in patients with open vs. laparoscopic resection.

Pathogenesis of complications of percutaneous endoscopic gastrostomy. A lesson in surgical principles.

In two comparable series of percutaneous endoscopic gastrostomy differing in only one technical detail, complications were significantly reduced by omitting traction on the gastrostomy tube to approximate the gastric to the abdominal wall. Radiologic studies show that traction shortened the tract (4.9 +/- 1.1 cm with traction, 11.6 +/- 2.3 cm without traction). In two patients with fasciitis, gross pericatheter leak of contrast into a short and patulous tract was observed. Tube extrusion and gastrointestinal bleeding from gastric ersion ulcers were eliminated when traction was not used. No peritonitis occurred as a result of not attempting to approximate the stomach to the abdominal wall. The data suggest that traction on the gastrostomy tube is not only unnecessary, but is the cause of many of the complications reported.

A polymorphic complex dinucleotide repeat at the telomeric D8S7 locus.

Two cosmids isolated from a flow-sorted chromosome 8 library by hybridization with pSW50 (D8S7) were screened for GT microsatellite sequences. Both contained a positive 900-bp Hind III-Xba I fragment. Sequencing revealed a complex dinucleotide repeat. Flanking oligonucleotide primers were synthesized, and the polymerase chain reaction products produced by these primers were typed within the CEPH panel of families. A two-allele polymorphism was identified that is in linkage disequilibrium with a previously described insertion-deletion polymorphism at this locus.

A 2.8 megabase YAC contig spanning D8S339, which is tightly linked to the Werner syndrome locus.

A number of gene loci, including the locus for Werner syndrome (WRN), map to proximal human chromosome 8p near the genetic marker D8S339. In this report, we present a long range physical map of an approximately 2.8 megabase yeast artificial chromosome contig centred on D8S339. In this map, we localize the WRN-linked polymorphic sequence-tagged sites (STS) D8S339 and D8S1055, as well as a novel polymorphic STS, D8S2297. We also refine the positions of three known gene loci, GTF2E2, GSR, and PPP2CB, relative to the location of WRN within the map.

Sequence identity locates CEBPD and FGFR1 to mapped human loci within proximal 8p.

The gene loci for human CEBPD (CCAAT enhancer binding protein, delta chain) and FGFR1 (fibroblast growth factor receptor) have been identified within two genetically mapped cosmids by sequence homology between rare cutter site regions and data base sequences for these loci. Cell hybrid and fluorescence in situ hybridization mapping places both of these loci within the chromosome region 8p11.2-->p11.1.

Support for founder effect for two lipoprotein lipase (LPL) gene mutations in French Canadians by analysis of GT microsatellites flanking the LPL gene.

Mutations in the human lipoprotein lipase (LPL) gene are one of the major causes of familial chylomicronemia. We have characterized two polymorphic GT microsatellites flanking this gene. Two LPL mutations that are extremely frequent in French Canadians appear to be in complete linkage disequilibrium with specific LPL microsatellite haplotypes indicating a founder effect within this population.

Identification of the human neuronal nicotinic cholinergic alpha 2 receptor locus, (CHRNA2), within an 8p21 mapped locus, by sequence homology with rat DNA.

We have identified a cosmid, at the D8S131 locus, that shows sequence homology with exon 2 of the rat gene for the neuronal nicotinic acetylcholine receptor alpha 2 subunit. A 357-bp sequence surrounding a rare cutter AscI site contains a 152-bp region of homology. The human CHRNA2 gene is therefore positioned at the D8S131 locus, which has been mapped to 8p21.

Effect of Wound Closure Technique on Wound Infection in the Morbidly Obese: results of a randomized trial.

The effect of suture obliteration of the subcutaneous dead space in morbidly obese abdominal wounds was studied in a randomized trial, comparing a pre-fascial retention suture technique (utilized for approximated of the thick panniculus) to controls where the skin was simply closed with staples. The wound infection rates were similar (11.8% for the sutured group versus 12.3% for controls, p 0.4), as were the total wound complication rates (26.5% for sutured group versus 21.9% for controls, p 0.4). Ultrasound study of the wounds closed without suturing the panniculus demonstrated no dead spaces. We conclude that no advantage is to be gained by suturing the subcataneous fat, however thick. The finding is of general application in wound closures involving thick layers of fat.

Inverted tandem duplication generates a duplication deficiency of chromosome 8p.

An adult female with sever mental retardation and dysmorphic features is described. A de novo chromosomal aberration involving 8p was found. The karyotype was 46, XX, inv dup (8) (p12----p23.1). Dosage studies with the DNA probe D8S7, which is located at 8p23----8pter, showed that the patient was monosomic for this marker. Thus the de novo rearrangement generated a duplication-deficiency chromosome. The possible mechanisms of formation of this abnormal chromosome are discussed.

Characterization of a human chromosome 8 cosmid library constructed from flow-sorted chromosomes.

A cosmid library for human chromosome 8 has been constructed from flow-sorted chromosomes in the vector sCos-1. This library is 85% human and has been arrayed into 210 microtiter plates representing four genome equivalents. Cosmids have been isolated with 10 of 11 probes representing nine different loci from chromosome 8.

Laparoscopic surgery for colorectal neoplasms.

Laparoscopy is being used to assist in an increasing number and variety of bowel procedures. However, when being used for neoplastic disease concerns of margins and adequacy of mesenteric dissection must be addressed. We've performed 110 laparoscopic-assisted bowel procedures, with 45 of these performed for neoplastic disease. Ninety-two bowel resections were performed including 24 subtotal, total, or proctocolectomies. In this chapter we review the results of our series, as well as other reported series, and discuss some of the controversies involved with laparoscopy for neoplastic disease.

Endogenous retroviruses provide the primary polyadenylation signal for two new human genes (HHLA2 and HHLA3).

By screening the expressed sequence tag (EST) database, we identified transcripts of two new human genes that are polyadenylated within a long terminal repeat (LTR) of the HERV-H endogenous retrovirus family. The first gene, termed HHLA2, is represented by two EST clones and one cDNA clone, all of which have a polyadenylated LTR as their 3' end. The gene has an open reading frame (ORF) of 414 amino acids with three immunoglobulin-like domains and is expressed primarily in intestinal tissues, kidney, and lung. Seven small EST clones from several different tissues were found for the second gene, termed HHLA3. As with HHLA2, all HHLA3 ESTs utilized a HERV-H LTR as the polyadenylation signal. Three types of alternatively spliced HHLA3 transcripts that could encode proteins of 76, 121, or 153 amino acids were detected. Interestingly, the ORF for two of these transcripts continues into the LTR. For both HHLA2 and 3, no major human transcripts that utilized a non-LTR polyadenylation signal were detected. Analysis of RNA from baboon, which lacks the LTRs at these genomic loci, showed that the baboon HHLA2 and 3 genes use other polyadenylation signals. This study demonstrates that ancient retroviral insertions have assumed gene regulatory functions during the course of human evolution.

Genomic organization, expression, and chromosome location of the human SNAIL gene (SNAI1) and a related processed pseudogene (SNAI1P).

Some of the zinc finger proteins of the snail family are essential in the formation of mesoderm during gastrulation and the development of neural crest and its derivatives. We have isolated the human SNAIL gene (HGMW-approved symbol SNAI1) and describe its genomic organization, having sequenced a region spanning more than 5882 bp. The human SNAIL gene contains three exons. The SNAIL transcript is 2. 0 kb and is found in placenta and adult heart, lung, brain, liver, and skeletal muscle. It codes for a protein of 264 amino acids and 29.1 kDa. This protein contains three classic zinc fingers and one atypical zinc finger. The human SNAIL protein is 87.5, 58.7, 50.9, 50.7, 55.4, and 31.5% identical to mouse Snail, chicken snail-like, zebrafish snail1, zebrafish snail2, Xenopus snail, and Drosophila snail proteins, respectively. The zinc finger region is 95.5% identical between human and mouse Snail. Because Drosophila snail and twist are important regulators during mesoderm development and because human TWIST mutations have been implicated in craniosynostosis, a cohort of 59 patients with craniosynostosis syndromes were screened for SNAIL mutations. None were found. By somatic cell and radiation hybrid mapping panels, SNAIL was localized to human chromosome 20q13.2, between markers D20S886 and D20S109. A SNAIL-related, putative processed pseudogene (HGMW-approved symbol SNAI1P) was also isolated and maps to human chromosome 2q33-q37.

Harmonic Scalpel vs. electrocautery hemorrhoidectomy: a prospective evaluation.

INTRODUCTION: Management of posthemorrhoidectomy pain remains a very unsatisfactory clinical dilemma. Compared with electrocautery and laser, the Harmonic Scalpel causes minimal lateral thermal injury during tissue dissection. PURPOSE: The aim of the study was to establish whether decreased lateral thermal injury translated into diminished posthemorrhoidectomy pain. METHODS: A prospective randomized trial comparing Harmonic Scalpel hemorrhoidectomy and electrocautery was undertaken. Fifty consecutive patients were randomized into two groups: Harmonic Scalpels and electrocautery hemorrhoidectomy. The indications included Grade III internal hemorrhoids with external components or Grade IV disease. Patients with additional anorectal pathology (fissure or fistula) were excluded, as were patients with neurologic deficits, chronic pain syndrome, and those already taking narcotic analgesics. Pain was assessed using a visual analog scale preoperatively and on postoperative Days 1, 2, 7, 14, and 28. Twenty-four-hour narcotic usage (Hydrocodone, 10 mg) was recorded on postoperative Days 1, 2, 7, 14, and 28. A three-quadrant modified Ferguson hemorrhoidectomy was performed with each patient in the prone jackknife position. RESULTS: Pain in the Harmonic Scalpel hemorrhoidectomy group was significantly less than in electrocautery patients on each postoperative day studied. Analgesic requirements were also significantly less in the Harmonic Scalpel group on Days 1, 2, 7, and 14. There was no correlation between postoperative pain and grade of hemorrhoid, status of the surgical incision (open vs. closed), or any other study variable. Fifty-five percent of Harmonic Scalpel patients returned to work within one week of surgery, compared with 23 percent of electrocautery patients. CONCLUSION: The study demonstrates significantly reduced postoperative pain after Harmonic Scalpel hemorrhoidectomy compared with electrocautery controls. The diminished postoperative pain in the Harmonic Scalpel group likely results from the avoidance of lateral thermal injury.