Isolation of novel human and mouse genes of the recA/RAD51 recombination-repair gene family.

Genes from the recA/RAD51 family play essential roles in homologous recombination in all organisms. Using sequence homologies from eukaryotic members of this family we have identified fragments of two additional mammalian genes with homology to RAD51. Cloning the full-length cDNAs for both human and mouse genes showed that the sequences are highly conserved, and that the predicted proteins have characteristic features of this gene family.

Biomechanical performance of cutting edge surgical needles.

The purpose of this study was to compare the biomechanical performance of cutting edge needles made of S45500 stainless steel alloy to Surgalloy stainless steel. The new high-nickel stainless steel alloy, Surgalloy, has superior performance characteristics over that of the other high-nickel stainless steel alloy, S45500. The Surgalloy needle is produced from a stronger stainless steel alloy than the S45500 needle.

Chromosomal aberrations induced by defined DNA double-strand breaks: the origin of achromatic lesions.

The mechanisms of formation of chromosomal aberrations are poorly understood, despite the common use of aberrations as a measure of the genetic effects of physical and chemical agents. We have used restriction endonucleases to introduce defined DNA double-strand breaks into mammalian cells, and measured chromosomal aberration formation relative to the activity of the endonuclease. The endonucleases AluI and Sau3AI remain active for a relatively short time under simulated cellular conditions and induce achromatic lesions ('gaps') in chromatids only within the first hour or two following treatment.

The XRCC2 DNA repair gene: identification of a positional candidate.

The human XRCC2 gene, complementing a hamster cell line (irs1) hypersensitive to DNA-damaging agents, was previously mapped to chromosome 7q36.1. Following radiation reduction of human/hamster hybrids, the gene was found to be associated with the marker D7S483.

High-efficiency stable DNA transfection using cationic detergent and glycerol.

We show that a brief exposure to a simple cationic detergent, in combination with a glycerol 'shock', can result in high frequencies of stable DNA transfection into mammalian cells. Using both Chinese hamster and human cell lines, frequencies of 1 per 1000, or even 1 per 100, viable cells can be achieved readily after optimizing the transfection conditions in a simple buffer. The mechanism of DNA transfer is proposed to differ from that for polycationic liposomes: as well as supplying a hydrophobic counterion, CDAB may promote a conformational change in DNA, allowing the DNA to be readily taken up after the glycerol shock to the cell.

Novel cypermethrin formulation for the control of sea lice on salmon (Salmo salar).

A novel formulation of cypermethrin was applied as a bath treatment to Atlantic salmon infested with sea lice on a commercial fish farm on the Isle of Skye, Scotland. Twenty 15 m x 15 m cages were treated with cypermethrin at a concentration of 5 micrograms/litre sea water. The numbers of sea lice of all stages were recorded on five fish per cage before the treatment and one, seven and 16 days after treatment.

A new computerized control unit for small bone surgical instruments.

The SmartDrive console represents an important advance in small bone surgery because it monitors and coordinates the operation of its handpieces. The SmartDrive console has the following unique features: 1) a handpiece recognition system; 2) an instrument speed display; 3) a handpiece display and monitoring system; 4) a torque instrument control system; 5) a temperature monitoring system; 6) and an irrigation system. Mechanical performance studies have been undertaken that have validated the accuracy of the monitoring systems of the consoles.

The joining of non-complementary DNA double-strand breaks by mammalian extracts.

We have developed a high efficiency system in which mammalian extracts join DNA double-strand breaks with non-complementary termini. This system has been used to obtain a large number of junction sequences from a range of different break-end combinations, allowing the elucidation of the joining mechanisms. Using an extract of calf thymus it was found that the major mechanism of joining was by blunt-end ligation following removal or fill-in of the single-stranded bases.

Innovations in oscillating bone saw blades.

The purpose of this study was to identify some of the determinants of saw-blade design that influence bone-cutting performance. Using a reproducible experimental model, saw-blade performance was judged by measuring the blade temperature and the rate of bone removal. The results of this study demonstrated that the rake angle and blade swing radius had significant influence on saw-blade performance.

Durability of oscillating bone saw blades.

The purpose of this study was to measure the durability of disposable saw blades using a standard bone-cutting experimental model that can be replicated in any laboratory. Using a constant cutting force, the bone-cutting efficiency was determined by recording the maximum cutting temperature and the rate of material removal. In this experimental study, porcine femurs as well as a synthetic bone substitute were used as the test samples for measuring cutting efficiency.

A technique for quantifying the performance of oscillating bone saw blades.

A new model has been developed to evaluate the performance of oscillating surgical saw blades used in medical-implant procedures. A test apparatus was constructed to maintain a constant cutting force between a blade driven by a pneumatic powered oscillating saw and the bone. Evaluations of saw-blade performance were determined using the following outcome measures: cutting time, volume of bone removal, and peak cutting temperature.

Pacemaker patient-triggered event recording: accuracy, utility, and cost for the pacemaker follow-up clinic.

Many pacemaker patients have vague symptoms following implantation. It is often difficult for the physician to ascertain if they are cardiac in origin. A new pacemaker feature has been introduced, Patient-Triggered Event Records (PTER), to help the physician with this diagnosis.

Mutations induced by DNA double-strand breaks: the influence of genomic site.

The transgenic CHO cell line PL61, carrying a recombinant SV40-gpt gene, was treated with restriction endonucleases to assess mutagenesis from defined DNA double-strand breaks. Mutations in gpt were measured under two conditions: a stringent condition where selection ensured that the closely-linked neo gene was retained functionally intact, or a relaxed condition without the requirement for neo gene function. Despite testing 18 different restriction endonucleases with various numbers of potential break-sites within the transgene, mutations were only found under relaxed selection conditions.

Another cause of surgical needle holder damage to surgical sutures.

The sharp edges of the box lock of the needle holder can inadvertently damage the suture during instrument ties. Compression of a monofilament nylon suture between the sharp edges of the box lock of a surgical needle holder damages the suture, reducing its breaking strength. This adverse effect has been eliminated by one manufacturer whose needle holder box lock has rounded edges and sufficient space to permit passage of the suture.

Ease of donning commercially available powder-free surgical gloves.

There are a wide variety of powder-free gloves that can now be used by surgeons. The purpose of this study was to quantify the forces required to don these powder-free surgical gloves. The lowest donning forces for wet hands was encountered with powder-free gloves coated with a hydrogel polymer.

Studies of determinants of glove hole puncture during electrosurgery.

Holes in surgical gloves are considered to be an important source of transmission of pathogens between patient and surgeon. The purpose of this study was to determine if electrosurgery could alter the integrity of latex surgical gloves. The effects of electrosurgery on 11 brands of commercially available latex surgical gloves were tested through an in vitro study that simulated the conditions in the operating room.

Knot performance of polypropylene sutures.

A mechanical performance test using an Instron Tensile Tester demonstrated the superior handling characteristics of Surgipro suture as compared to Prolene suture that facilitated knot construction without suture breakage. For both granny and square knots, the knot run down forces for the Surgipro sutures were significantly less than those encountered for comparable knots for Prolene sutures. This propensity of the two-throw knots of Surgipro sutures to advance without breakage considerably facilitated knot construction.

Needle puncture resistance of surgical gloves, finger guards, and glove liners.

New puncture resistant materials are being developed for health professional use as protection against disease and needle stick injuries. The needle puncture resistance of protective gloves and glove liners from DePuy DuPont Orthopaedics and of finger guards from Zimmer was evaluated using a computerized needle penetration system to determine maximal penetration forces and the penetration work required for taper point and for cutting edge needles to penetrate these membranes. The Medak portion of the Life Liner glove liner and the Spectra portion of the FingGuard finger guard offered remarkable resistance against needle penetration as compared to the other glove liners and gloves tested.

The genetic basis of cellular recovery from radiation damage: response of the radiosensitive irs lines to low-dose-rate irradiation.

Recovery from the lethal effects of irradiation is commonly found when cultured mammalian cells are irradiated at low dose rates when compared to the same cells irradiated at higher dose rates. However, this cellular recovery process is severely reduced or absent in a number of radiosensitive cell lines, including those derived from the human disorder ataxia telangiectasia (AT). The genetic and molecular basis of such recovery processes is not understood, despite their importance.

Strain-based fatigue analysis of wheelchairs on a double roller fatigue machine.

Results are presented from an experimental program that recorded the outputs of strain gages mounted on two wheelchair frames (one manual, one power) as the wheelchairs were run on a double roller fatigue machine. Rectangular strain gage rosettes were attached to the frames near the cross tube center pin and on the side frame behind a front caster. Thirty data sets were recorded from each rosette on each wheelchair frame.

Successful excision of a giant acoustic neuroma in the third trimester of pregnancy.

Intracranial neoplasms presenting during pregnancy are uncommon. We report the case of a woman with a giant acoustic neuroma, presenting with hyperemesis gravidarum, and detail the surgical excision of the tumour during the third trimester. The case illustrates the unusual presentation and that such surgery can be performed safely without detriment to mother or fetus.

Enhancing needle durability by silicone coating of surgical needles.

The purpose of this study was to assess the effect of coating surgical needles with silicone on their durability. Needle durability is a measure of needle sharpness after repeated passage through tissue. Needle sharpness was determined by quantitating the energy required to pass a designated needle repeatedly (20 times) through porcine skin, linea alba, colon, and aorta.

A new powder-free glove with a textured surface to improve handling of surgical instruments.

A latex surgical glove has been designed to have a textured surface that stimulates the surface of intact skin. This textured surface enhances security of grasp of surgical instruments under wet and dry conditions without altering tactile discrimination. The unique hydrogel polymer of this glove allows the glove to be donned with either wet or dry hands without the use of cornstarch lubricants.