Electromagnetic Metal Forming

Some results of an experimental and theoretical investigation of the dynamic forming of thin-walled tubes and flat circular diaphragms by the electromagnetic metal forming process are given. The paper is divided into two parts.

Part 1—The magnetic forming process is described and its use as a production technique is discussed. The process is a high strain-rate technique suitable for forming relatively light gauge material; the forces causing deformation result from the interaction of the current in specially constructed coils and the resulting eddy currents induced in the workpiece. The source of energy is a capacitor bank which can be discharged rapidly through the work-coil. The experiments described were performed using a specially constructed 16 kj discharge unit. The method of constructing work-coils and the failures experienced with these coils in service are described.

Thin-walled copper and aluminium tubes were expanded by means of internal solenoidal work-coils of various lengths. The strain distribution and forming efficiency is presented, together with results showing the variation of process efficiency with changes in the primary circuit parameters. The strain distribution for a circular aluminium alloy diaphragm bulged by means of a flat spiral coil is given.

Typical primary current waveforms are given and the changes in waveform and discharge current frequency due to different workpiece materials and changes in primary circuit parameters are indicated.

Part 2—An attempt is made to determine theoretically the forces acting on one of the aluminium alloy tubes expanded and described in the work of Part 1. The currents in the work-coil and workpiece are calculated using the experimentally determined current waveform and the calculated value of workpiece inductance. A rudimentary method is developed for relating pressure on the workpiece to the primary and secondary currents and, using this, the radial motion of the tube is predicted. Although the analysis involves the use of a number of simplifications and approximations, the theoretical results obtained are of the same magnitude as would be expected by reference to other high-rate forming processes.

exomeSuite: Whole exome sequence variant filtering tool for rapid identification of putative disease causing SNVs/indels

Exome and whole-genome analyses powered by next-generation sequencing (NGS) have become invaluable tools in identifying causal mutations responsible for Mendelian disorders. Given that individual exomes contain several thousand single nucleotide variants and insertions/deletions, it remains a challenge to analyze large numbers of variants from multiple exomes to identify causal alleles associated with inherited conditions. To this end, we have developed user-friendly software that analyzes variant calls from multiple individuals to facilitate identification of causal mutations. The software, termed exomeSuite, filters for putative causative variants of monogenic diseases inherited in one of three forms: dominant, recessive caused by a homozygous variant, or recessive caused by two compound heterozygous variants. In addition, exomeSuite can perform homozygosity mapping and analyze the variant data of multiple unrelated individuals. Here we demonstrate that filtering of variants with exomeSuite reduces datasets to a fraction of a percent of their original size. To the best of our knowledge this is the first freely available software developed to analyze variant data from multiple individuals that rapidly assimilates and filters large data sets based on pattern of inheritance.

Advances in imaging of Stargardt disease

Stargardt disease (STGD1) is an autosomal-recessively inherited condition often associated with mutations in ABCA4 and characterized by accumulation of autofluorescent lipofuscin deposits in the retinal pigment epithelium (RPE). Non-invasive imaging techniques including fundus autofluorescence (FAF), spectral domain optical coherence tomography (SD-OCT) and adaptive optics scanning laser ophthalmoscopy (AOSLO) have the potential to improve understanding of vision loss in patients with STGD. We describe a comprehensive approach to the study of patients with STGD. Measures of retinal structure and FAF were correlated with visual function including best-corrected visual acuity (BCVA), color vision, kinetic and static perimetry, fundus-guided microperimetry and full-field and multifocal electroretinography. Mutation analysis of the ABCA4 gene was carried out by sequencing the complete coding region. Preliminary data suggest that a combination of imaging modalities may provide a sensitive measure of disease progression and response to experimental therapies in patients with STGD.

Expression of reverse cholesterol transport proteins ATP-binding cassette A1 (ABCA1) and scavenger receptor BI (SR-BI) in the retina and retinal pigment epithelium

AIMS

Excessive lipid accumulation in Bruch's membrane (BrM) is a hallmark of ageing, the major risk factor for age-related macular degeneration (AMD). Retinal pigment epithelial (RPE) cells may utilise reverse cholesterol transport (RCT) activity to move lipid into BrM, mediated through ATP-binding cassette A1 (ABCA1) and scavenger receptor BI (SR-BI).

METHODS

ABCA1 expression was assessed by reverse transcription polymerase chain reaction (RT-PCR) and western blotting of human RPE cell extracts. Lipid transport assays were performed using radiolabelled photoreceptor outer segments (POS). ABCA1 and SR-BI expression was examined in normal mouse eyes by immunofluorescence staining. BrMs of ABCA1 and SR-BI heterozygous mice were examined microscopically.

RESULTS

Human RPE cells expressed ABCA1 mRNA and protein. The ABCA1 and SR-BI inhibitor glyburide (also known as glibenclamide) abolished basal transport of POS-derived lipids in RPE cells in the presence of high-density lipoprotein. Mouse retina and RPE expressed ABCA1 and SR-BI. SR-BI was highly expressed in RPE. BrMs were significantly thickened in SR-BI heterozygous mice, but not in ABCA1 heterozygous mice.

CONCLUSION

RPE cells express ABCA1 and SR-BI. This implies a significant role for SR-BI and ABCA1 in lipid transport and RCT in the retina and RPE.

The successful use of recombinant factor VIIa in a patient with vascular-type Ehlers-Danlos syndrome

Vascular-type Ehlers-Danlos syndrome is an inherited connective tissue disorder resulting in an increased risk of serious peri-operative bleeding during surgery for spontaneous organ or vessel rupture. The excessive bleeding may result in coagulopathy, and thus compound the difficulty in securing surgical haemostasis. With the advent of recombinant factor VIIa, a new therapy has become available for the management of intractable surgical bleeding.

A sheet-bulging machine with closed-loop control

The design and performance of a machine for testing sheet material in the plastic range is described. The material is stressed in uniform biaxial tension by means of the hydrostatic bulge test. Test variables are measured by electrical transducers and an analogue unit is employed to permit autographic recording of the diagram relating true stress and natural strain. Closed-loop control of the rate of straining is achieved with an electro-hydraulic actuator; the feedback signal is derived from the analogue unit and the test can be controlled on the basis of a computed parameter such as true stress or natural strain.

Unusual hindgut malrotation and associated mesenteric vascular abnormality presenting as large bowel obstruction in an adult

We report an unusual and not previously described congenital hindgut malrotation presenting as large bowel obstruction in an adult.

Factors affecting attrition in a longitudinal study of patients with AIDS

Anecdotal data have suggested that retention of HIV-infected patients with immune recovery in longitudinal studies may be difficult as they resume normal activities. This study evaluated risk factors for attrition among patients with AIDS in a cohort study in the era of highly active antiretroviral therapy. Patients with AIDS enrolled in the Longitudinal Study of Ocular Complications of AIDS were evaluated every three months with demographic, clinical and laboratory data collected. Lost to follow-up was defined as any patient who missed all study visits and could not be contacted for 12 consecutive months, who had not died and who did not re-enter the study at a later date. Of the 1,052 patients studied, 77 (7.3%) were lost to follow-up (rate = 0.03/person year). In the multivariate analysis, factors associated with attrition were CD4+ T-cell count category (hazard ratio (HR) = 2.03; 95%CI: 1.01, 4.24; P = 0.05 for CD4+ count < or = 50 cells/microL and HR = 1.96; 95%CI: 1.12, 3.40; P = 0.02 for CD4+ count 51-200 cells/microL) and detectable HIV viral load (HR = 1.29; 95%CI: 1.07, 1.53; P < 0.001 for HIV viral load >400 copies/mL). These data suggest that patients with compromised immunologic status are at an increased risk for being lost to follow-up.

Light and inherited retinal degeneration

Light deprivation has long been considered a potential treatment for patients with inherited retinal degenerative diseases, but no therapeutic benefit has been demonstrated to date. In the few clinical studies that have addressed this issue, the underlying mutations were unknown. Our rapidly expanding knowledge of the genes and mechanisms involved in retinal degeneration have made it possible to reconsider the potential value of light restriction in specific genetic contexts. This review summarises the clinical evidence for a modifying role of light exposure in retinal degeneration and experimental evidence from animal models, focusing on retinitis pigmentosa with regional degeneration, Oguchi disease, and Stargardt macular dystrophy. These cases illustrate distinct pathophysiological roles for light, and suggest that light restriction may benefit carefully defined subsets of patients.

On the Parameters of the Magnetic Forming Process

The present state of forming and of the development of analytical design techniques for the process is reviewed briefly. A comprehensive analysis of the expansion of a tube by means of an internal solenoidal coil is given; this contains new expressions for the circuit parameters and magnetic pressure and takes account of the depth of the coil conductors.

The analytical method is tested by obtaining numerical solutions and comparing these with the results of experiments in which aluminium, copper and steel tubes were formed with various discharge energies and using coils having different conductor dimensions. It is shown that the analytical method gives accurate results and is convenient to use for design purposes to optimize the process.

Children's surgery performed by adult general surgeons in Scotland: the present and future

OBJECTIVE

The aim of this study was to determine the extent and the future of paediatric surgery performed in Scotland outside of the designated surgical paediatric centres.

MATERIALS AND METHODS

An anonymous questionnaire was sent to all 111 Scottish members of the Association of Surgeons of Great Britain and Ireland. There was a response rate of 69%.

RESULTS

Overall, 45% of responders operated on children. This was independent of the surgeon's age but was related to the type of hospital that the surgeon worked in. Eighty-four per cent of responders had a lower age limit under which they would not operate and 94% stated that there were specific circumstances where they would not operate. A mean of 18.5 elective procedures (range 0-250, median two) and six emergency procedures (range 0-30, median five) were carried out by each surgeon operating on children under the age of five per annum. Only 13% of responders thought that their successor would operate on children.

CONCLUSIONS

Non-specialist paediatric surgery in Scotland is currently provided by a significant number of surgeons whose successors will not continue to provide a comparative paediatric service. This has implications for local provision of care, emergency management and capacity of existing children's hospitals in the future.

Screening for abdominal aortic aneurysm in a geographically isolated area

Background

Screening for abdominal aortic aneurysm has been shown to reduce aneurysm-related mortality, but the applicability of the results to the whole of the UK has been questioned. This study examined screening in a remote and rural area.

Methods

Over 3 years, men aged 65–74 years were offered screening in the community by ultrasonography, usually in general practitioner surgeries. Men with an aneurysm were rescanned at intervals or assessed for surgery. The screening and hospital costs of the programme were calculated.

Results

Some 9323 men were offered screening of whom 8355 (89·6 per cent) attended. Uptake was high in all areas. A total of 430 scans (5·1 per cent) were abnormal; 40 men had an aneurysm greater than 55 mm in diameter. Twenty further men had an aorta that enlarged to greater than 55 mm during follow-up. A total of 54 men had elective repair with one death (mortality rate 2 per cent). The cost of screening alone was £16 per invitation and the overall cost of the programme, including surgery, was £58 per invitation.

Conclusion

Screening for abdominal aortic aneurysm can be carried out in a remote and rural area with high uptake, acceptable clinical results and at no greater cost than in more densely populated areas.

Whole-leg duplex mapping for varicose veins: observations on patterns of reflux in recurrent and primary legs, with clinical correlation

BACKGROUND

the variability of venous reflux patterns complicate the management of venous disease. Our study investigates specific variations in venous anatomy and patterns of reflux in varying clinical situations.

METHODS

prospective analysis of 464 legs in 355 patients was performed by complete duplex venous mapping of both primary and recurrent varicose veins. Hand Held Doppler (HHD) and Duplex Ultrasonography (Duplex US) observations in the popliteal fossa were compared in a subgroup of 89 patients with primary varicose veins. Distribution of venous system disease was correlated with clinical severity in a subgroup of 117 affected legs which was representative of the overall study group.

RESULTS

sapheno-femoral junction (SFJ) incompetence predominated in both primary and recurrent varicose veins. Only 21% of primary legs and 25% of recurrent legs had sapheno-popliteal junction (SPJ) incompetence. SPJ incompetence was present in only 42% of cases where reflux in the popliteal region on HHD had been demonstrated. A proportion of both primary and recurrent varicose veins had evidence of deep venous incompetence (DVI). Sixty-four percent of primary leg ulcer patients had superficial incompetence alone. In patients with recurrent varicosities and ulceration, 57% had SPJ incompetence, 64% multiple sites and 50% DVI.

CONCLUSION

the complex variations of varicose vein anatomy and functional pathology in the lower limb are currently best assessed by complete whole-leg venous duplex mapping.

Relatedness of Escherichia coli colonizing women longitudinally

PURPOSE

The longitudinal colonization patterns by Escherichia coli of the vaginal introitus and urinary tract were investigated.

MATERIALS AND METHODS

Cultures of the vaginal introitus and midstream urine were collected once a week for 12 consecutive weeks from five women with (patients) and five without (controls) a history of urinary tract infection (UTI).

RESULTS

A total of 63 E. coli isolates was obtained from the 10 women, 26 from controls and 37 from patients. The bacterial counts of E. coli present in control individuals were uniformly low, < or = 200 E. coli/mL. The numbers in patients were higher and more variable, reaching > 10(5)/mL in urine and vaginal specimens. In 16 instances, E. coli was present in the urine and the vaginal introitus concurrently (matched isolates). Random amplified polymorphic DNA (RAPD) fingerprinting was used to characterize all matched E. coli isolates. Concurrent vaginal and urinary tract colonization was more common in the patient population, and usually, the same E. coli strain was present at both sites; only 15% of the matched isolates represented different strains. The RAPD fingerprinting was also carried out on selected isolates recovered from four patients and three control individuals over the 12-week study period. Colonization of the vaginal introitus and urinary tract in these individuals varied over time. Generally, however, a predominant E. coli strain was present in the vaginal milieu, urinary tract, or both, either continuously (for as long as 9 consecutive weeks in one patient) or intermittently.

CONCLUSION

The results support the concept that the vaginal mucosa acts as reservoir of E. coli which may enter the urinary tract.

World association for the advancement of veterinary parasitology (WAAVP): second edition of guidelines for evaluating the efficacy of equine anthelmintics

These guidelines have been designed to assist in the planning, operation and interpretation of studies which would serve to assess the efficacy of drugs against internal parasites of horses. Although the term anthelmintic is used in the title and text, these guidelines include studies on drug efficacy against larvae of horse bot flies, Gasterophilus spp., which are non-helminth parasites commonly occurring in the stomach of horses. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on selection of animals, housing, feed, dose titration, confirmatory and clinical trials, record keeping and necropsy procedures. These guidelines should assist both investigators and registration authorities in the evaluation of compounds using comparable and standard procedures with the minimum number of animals.

Ocular manifestations of leukemia: leukemic infiltration versus infectious process

OBJECTIVE

To determine whether specific guidelines can be developed to distinguish whether retinal infiltration in leukemia patients represents infection or neoplasia.

DESIGN

Retrospective noncomparative interventional case series.

PARTICIPANTS

Six patients recently seen at University of California San Francisco with retinal infiltrates in a setting of leukemia, for which adequate written and photographic information of disease course was available.

INTERVENTION

Observation consisted of retrospective review of clinic charts, hospital medical records, and fundus photographs.

MAIN OUTCOME MEASURES

Determination of whether retinal infiltrates represented neoplasia or infection was made by review of medical records.

RESULTS

In this series, neoplastic retinal infiltrates were found in patients who had newly diagnosed leukemia and those who were in blast crisis. In contrast, the two patients who were in complete remission, but had undergone bone marrow transplantation, had retinal infiltrates attributable to infection.

CONCLUSIONS

Every patient with retinal infiltrates in the setting of newly or previously diagnosed leukemia requires a systemic and central nervous system workup before the initiation of ophthalmologic treatment. The systemic status of the patient is highly informative in determining whether infection or neoplasia is responsible for the infiltration.

Correction of the retinal dystrophy phenotype of the RCS rat by viral gene transfer of Mertk

The Royal College of Surgeons (RCS) rat is a widely studied animal model of retinal degeneration in which the inability of the retinal pigment epithelium (RPE) to phagocytize shed photoreceptor outer segments leads to a progressive loss of rod and cone photoreceptors. We recently used positional cloning to demonstrate that the gene Mertk likely corresponds to the retinal dystrophy (rdy) locus of the RCS rat. In the present study, we sought to determine whether gene transfer of Mertk to a RCS rat retina would result in correction of the RPE phagocytosis defect and preservation of photoreceptors. We used subretinal injection of a recombinant replication-deficient adenovirus encoding rat Mertk to deliver the gene to the eyes of young RCS rats. Electrophysiological assessment of animals 30 days after injection revealed an increased sensitivity of treated eyes to low-intensity light. Histologic and ultrastructural assessment demonstrated substantial sparing of photoreceptors, preservation of outer segment structure, and correction of the RPE phagocytosis defect in areas surrounding the injection site. Our results provide definitive evidence that mutation of Mertk underlies the RCS retinal dystrophy phenotype, and that the phenotype can be corrected by treatment of juvenile animals. To our knowledge, this is the first demonstration of complementation of both a functional cellular defect (phagocytosis) and a photoreceptor degeneration by gene transfer to the RPE. These results, together with the recent discovery of MERTK mutations in individuals with retinitis pigmentosa, emphasize the importance of the RCS rat as a model for gene therapy of diseases that arise from RPE dysfunction.

Community mortality after ruptured abdominal aortic aneurysm is unrelated to the distance from the surgical centre

BACKGROUND

Ruptured abdominal aortic aneurysm (RAAA) carries a high community mortality. Raigmore Hospital, Inverness serves Highland Region, an area the size of Wales with a population of 204,000. The aim of this retrospective review was to determine the community mortality and hospital mortality rates from RAAA in Highland Region and to assess whether distance travelled had any significant impact on survival.

METHODS

Data were retrieved from hospital records, the Registrar General for Scotland and the Information and Statistics Division of the National Health Service in Scotland about patients diagnosed with RAAA between 1992 and 1999.

RESULTS

Of 198 patients with RAAA, 131 (66 per cent) were transferred to Raigmore Hospital while the other 67 (34 per cent) died in a community hospital or at home. Of those reaching Raigmore 109 (83 per cent) had surgery, of whom 65 (60 per cent) survived. The overall community mortality rate was 67 per cent while the hospital mortality rate was 50 per cent. The hospital and community mortality rates for patients living within 50 miles of Raigmore Hospital were 60 and 67 per cent respectively, compared with 26 and 68 per cent for those living more than 50 miles away.

CONCLUSION

Distance from Raigmore Hospital had no significant impact on community mortality from RAAA.

Saxitoxin: an anesthetic of the deepithelialized rabbit cornea

PURPOSE

The aim of the current study was to define the efficacy of saxitoxin as a corneal anesthetic in rabbits after mechanical corneal abrasion and photorefractive keratectomy (PRK).

METHODS

Twelve Dutch belted rabbits were given a single 1.2-microg dose of saxitoxin or vehicle after mechanical abrasion of the cornea. Corneal sensation was evaluated hourly for 6 hours. A second group of 12 Dutch belted rabbits was given a 1.2-microg dose of saxitoxin or vehicle every 5 hours for 30 hours after PRK. Corneal sensation was evaluated after 5, 10, 15, 20, 25, and 30 hours. Pachometry was performed before PRK and again after the epithelial defects had healed. The rate of epithelial defect closure was assessed by measuring the epithelial defect size 25, 42, 65, 88, and 113 hours after PRK.

RESULTS

A dose of 1.2 microg of saxitoxin given every 5 hours produced continuous corneal anesthesia after PRK. There was no difference in the rate of wound healing between eyes treated with saxitoxin and vehicle. There was no difference in the degree of wound healing, as measured by pachometry, between eyes treated with saxitoxin and vehicle. There were no apparent ocular or systemic toxic effects from saxitoxin administration.

CONCLUSION

At a dose of 1.2 microg, saxitoxin is a safe, effective, long-acting corneal anesthetic in rabbits after PRK.

Macular pigment and lutein supplementation in retinitis pigmentosa and Usher syndrome

PURPOSE

To determine macular pigment (MP) in patients with inherited retinal degeneration and the response of MP and vision to supplementation of lutein.

METHODS

Patients with retinitis pigmentosa (RP) or Usher syndrome and normal subjects had MP optical density profiles measured with heterochromatic flicker photometry. Serum carotenoids, visual acuity, foveal sensitivity, and retinal thickness (by optical coherence tomography [OCT]) were quantified. The effects on MP and central vision of 6 months of lutein supplementation at 20 mg/d were determined.

RESULTS

MP density in the patients as a group did not differ from normal. Among patients with lower MP, there was a higher percentage of females, smokers, and light-colored irides. Disease expression tended to be more severe in patients with lower MP. Inner retinal thickness by OCT correlated positively with MP density in the patients. After supplementation, all participants showed an increase in serum lutein. Only approximately half the patients showed a statistically significant increase in MP. Retinal nonresponders had slightly greater disease severity but were otherwise not distinguishable from responders. Central vision was unchanged after supplementation.

CONCLUSIONS

Factors previously associated with lower or higher MP density in normal subjects showed similar associations in RP and Usher syndrome. In addition, MP in patients may be affected by stage of retinal disease, especially that leading to abnormal foveal architecture. MP could be augmented by supplemental lutein in many but not all patients. There was no change in central vision after 6 months of lutein supplementation, but long-term influences on the natural history of these retinal degenerations require further study.

Host pathogenesis in urinary tract infections

Urinary tract infections (UTIs) are the result of an interaction between bacterial virulence and host defense factors that compete to invade or protect the host, respectively. Research over the past 30 years has demonstrated that vaginal colonization with uropathogens precedes most UTIs. Receptivity of the vaginal mucosa for uropathogens is an essential initial step in vaginal mucosa colonization. When vaginal and buccal epithelial cells were collected from patients susceptible to reinfection and compared with such cells obtained from controls resistant to UTIs, the strains that caused cystitis adhered much more avidly to the epithelial cells from susceptible women. These genotypic traits for epithelial cell receptivity may be a major susceptibility factor in UTIs. The presence or absence of blood group determinants on the surface of uroepithelial cells may influence an individual's susceptibility to UTIs. The protective effect in women with the secretor phenotype may be due to fucosylated structures at the cell surface which decrease the availability of putative receptors for Escherichia coli. Susceptibility among women who do not secrete blood group antigens may be due to specific E. coli-binding glycolipids that are absent in women who secrete blood group antigens. Recent studies have shown that the vaginal fluid, which forms an interface between uropathogens and epithelial cells, also influences vaginal colonizations.

Epidemiology of parasitic gastrointestinal nematode infections of ruminants on smallholder farms in central Kenya

In order to establish the infection pattern with gastrointestinal nematodes in ruminants in the central Kenya highlands, a study was carried out in 58 smallholder farms. The study involved monthly faecal examinations from sheep, goats and cattle and pasture sampling from eight communal grazing areas. Each month, six Dorper worm-free tracer lambs were introduced and four locally grazed cross-bred sheep were purchased for parasite recovery. The mean faecal egg counts (FEC) for cattle were low throughout the study period, whereas those for sheep and goats showed a seasonal pattern with high levels of infection occurring during the two main rainy seasons, especially in March, April and October. There were significant differences in egg counts over time and among farms. Haemonchus contortus was the most prevalent nematode in the tracer lambs whereas the previously exposed locally grazed sheep had significantly lower numbers of H contortus but significantly higher numbers of Trichostrongylus species The highest levels of infection in the tracer lambs occurred in November 1995 and January, May and June 1996. Based on this study, it is now possible to explore the possibility of using strategic treatments for the control of parasitic gastroenteritis in this area of Kenya.

The influence of relative resistance and urea-supplementation on deliberate infection with Teladorsagia circumcincta during winter

The consequences for lambs of infection over the winter with Teladorsagia circumcincta were quantified by deliberate, trickle infection of selected animals at 7 months of age. Infected and control uninfected animals were each allocated into four groups, relatively resistant animals on a normal diet, relatively resistant animals on an isocaloric diet supplemented with urea, and relatively susceptible animals on the same two diets. Resistance and susceptibility was assessed by faecal egg counts following natural infection during the summer preceding the deliberate infection. During the deliberate infection egg counts remained low and most parasites recovered at necropsy were inhibited larvae. Nonetheless, infection reduced weight gain, decreased albumin and fructosamine concentrations and provoked a noticeable pepsinogen and eosinophil response. As most larvae were inhibited these responses may have been largely a consequence of immuno-inflammatory responses in the host rather than the direct action of parasites themselves. Relatively resistant animals on the supplemented diet allowed fewer larvae to establish and had higher fructosamine concentrations, higher albumin concentrations and decreased pepsinogen responses. Therefore, a combination of relatively resistant sheep and nutritional supplementation appears most efficient at controlling infection.

Safety of a single duplex scan to exclude deep venous thrombosis

BACKGROUND

Guidelines advocate that a negative ultrasonographic scan needs to be followed by venography, or a repeat scan after 1 week, to detect potentially missed calf vein thrombosis. This study aimed to evaluate whether anticoagulation can safely be withheld on the basis of a single negative duplex scan in patients presenting with suspected deep venous thrombosis (DVT).

METHODS

Duplex scan reports, case notes and questionnaires returned by general practitioners of patients with suspected DVT were analysed retrospectively. The main outcome measure was occurrence of an adverse thromboembolic event, a symptomatic DVT or a pulmonary embolism, within 3 months after a negative duplex scan.

RESULTS

Some 537 patients had 706 leg scans performed, the majority because of leg symptoms or to look for indirect evidence of pulmonary embolism. Among 352 patients, who had 429 negative leg scans, four possible adverse events were identified. The rate of adverse outcome was therefore 1.1 per cent per patient and 0.9 per cent per leg.

CONCLUSION

Withholding anticoagulation in patients who had a single, complete, negative duplex scan is safe. A repeat scan should be performed if there is ongoing high clinical suspicion and considered in patients in whom the calf veins could not be visualized.

Laparoscopic adrenalectomy is superior to an open approach to treat primary hyperaldosteronism

We reviewed our institutional experience with primary hyperaldosteronism to compare clinical outcomes after laparoscopic versus open adrenalectomy. All patients surgically treated for primary hyperaldosteronism from 1988 through 1999 are included in this study. Patients were assigned to either the LA (laparoscopic) or OA (open) group depending on the initial surgical approach selected for treatment. Records were reviewed to determine demographics, operative results, and complications. Twenty-four patients were surgically treated for primary hyperaldosteronism. There were no significant differences between groups with respect to age, weight, number of preoperative antihypertensive medications, or preoperative potassium level. The results of adrenalectomy with respect to number of postoperative antihypertensive medications or serum potassium level were also similar. Operative times were not significantly different (191 +/- 53 minutes for OA and 205 +/- 88 minutes for LA) between groups, but four LA patients were converted to OA. Estimated blood loss was 401 +/- 513 cm3 for OA and 127 +/- 131 cm3 for LA (P = 0.07). Hospital length of stay was 6.7 +/- 3.7 days for OA and 3.3 +/- 2.7 days for LA (P = 0.02). Complications were nine for OA and three for LA (P = 0.001 by Pearson's Chi square). LA is similar to OA in the treatment of primary hyperaldosteronism. The significantly fewer complications and shorter length of hospital stay associated with LA makes the laparoscopic approach the preferred method for treating primary hyperaldosteronism.

Characterization of an immortalized human vaginal epithelial cell line

PURPOSE

Adherence of type 1 piliated Escherichia coli to vaginal mucosa plays a major role in the pathogenesis of ascending urinary tract infections (UTIs) in women. Progress in understanding the mechanism of adherence to the vaginal surface could be enhanced by the utilization of well-characterized vaginal epithelial cells. The objective of this study was to immortalize vaginal epithelial cells and study their bacterial adherence properties.

MATERIALS AND METHODS

Primary vaginal cells were obtained from a normal post-menopausal woman, immortalized by infection with E6/E7 genes from human papillomavirus 16 (HPV 16) and cultured in serum free keratinocyte growth factor medium.

RESULTS

Positive immunostaining with a pool of antibodies to cytokeratins 1, 5, 10 and 14 (K1, K5, K10 and K14) and to K13 confirmed the epithelial origin of these cells. The immortalized cells showed binding of type 1 piliated E. coli in a pili specific and mannose sensitive manner.

CONCLUSION

This model system should facilitate studies on the interaction of pathogens with vaginal mucosal cells, an essential step in the progression of ascending UTIs in women.

Benign diagnosis by image-guided core-needle breast biopsy

Image-guided core-needle breast biopsy (IGCNBB) is widely used to evaluate patients with abnormal mammograms; however, information is limited regarding the reliability of a benign diagnosis. The goal of this study was to demonstrate that a benign diagnosis obtained by IGCNBB is accurate and amenable to mammographic surveillance. Records of all patients evaluated by IGCNBB from July 1993 through July 1996 were reviewed. Biopsies were classified as malignant, atypical, or benign. All benign cases were followed by surveillance mammography beginning 6 months after IGCNBB. Of the 1110 patients evaluated by IGCNBB during the study period, 855 revealed benign pathology. A total of 728 of the 855 patients (85%) complied with the recommendation for surveillance mammography. A total of 196 IGCNBBs were classified as malignant; 59 cases were classified as atypical. The atypical cases were excluded from the statistical analysis. Only two patients have demonstrated carcinoma after a benign IGCNBB during the 2-year minimum follow-up period. The sensitivity and specificity of a benign result were 100.0 and 98.9 per cent, respectively. A benign diagnosis obtained by IGCNBB is accurate and therefore amenable to mammographic surveillance. The results of this study support IGCNBB as the preferred method of evaluating women with abnormal mammograms.

Evaluation of the bacterial flora of the prostate using a 16S rRNA gene based polymerase chain reaction

PURPOSE

The role of bacteria in the chronic pelvic pain syndrome (nonbacterial prostatitis and prostatodynia) is controversial and difficult to assess because the bacterial flora of the prostate is not well defined. Polymerase chain reaction (PCR) is a highly sensitive molecular method of bacterial detection. It confirms the sterility of tissue with a high level of confidence and detects small numbers of microbial agents that may represent pathogens. We performed PCR to determine bacterial colonization of the prostate in presumably healthy men and in those undergoing simple or radical prostatectomy.

MATERIALS AND METHODS

We analyzed 28 prostate samples from 18 organ donors from whom prostate tissue was obtained under sterile surgical conditions at organ withdrawal, 14 sterile surgical prostate specimens from 7 patients undergoing radical prostatectomy for prostate cancer who previously underwent transrectal biopsy and 6 sterile surgical specimens from 2 men who underwent simple prostatectomy for benign prostatic hyperplasia (BPH), including 1 with an indwelling catheter for several weeks. For PCR we used 2 sets of primers to detect bacterial 16S rRNA gene sequences. Normal prostate tissue seeded in vitro with known numbers of Escherichia coli was used to assess the sensitivity of PCR.

RESULTS

Only 3 of the 28 organ donor samples had histological signs of minimal inflammation and all other samples appeared to be normal without evidence of inflammatory reaction. All of these samples were PCR negative. Of several PCR control reactions the mixture of prostate tissue seeded with known numbers of E. coli demonstrated the high sensitivity of the assay, allowing the detection of as few as 6 bacteria in the presence of 25 mg. of prostate tissue. A focal and heterogeneous distribution of inflammation and infection was noted in the 14 radical prostatectomy specimens. In the prostate cancer and BPH groups there was a strong association of inflammation with positive PCR findings. Of 11 samples 3 without but all 9 with inflammation were PCR positive.

CONCLUSIONS

PCR is a highly sensitive method for detecting bacteria in the prostate. In our study negative PCR reactions in the prostate tissue of apparently healthy men made the presence of normal bacterial flora in the prostate extremely unlikely. The presence of bacteria and/or inflammation in radical prostatectomy specimens was found to be a localized process. Concordance between inflammation and positive PCR results in simple and radical prostatectomy specimens suggests that bacteria may frequently have a role in histologically inflammatory prostatitis.

Roles of glycoproteins and oligosaccharides found in human vaginal fluid in bacterial adherence

Adherence of type 1-piliated Escherichia coli to carbohydrate structures of vaginal mucosa plays a major role in the pathogenesis of ascending urinary tract infections in women. Colonization of the vaginal introitus is influenced by interactions between pathogens, vaginal fluid, and vaginal epithelium. In this study, the type and amount of carbohydrates and glycoproteins present in vaginal fluid were determined. Free and protein-bound oligosaccharides in vaginal fluid specimens were analyzed by fluorophore-assisted carbohydrate electrophoresis (FACE) and high-pressure liquid chromatography (HPLC). Two-dimensional electrophoretic separations of vaginal fluid glycoproteins were performed together with bacterial overlay assays. The results of FACE showed that the majority of the oligosaccharides are in the free state and the bound oligosaccharides are undetectable. HPLC analysis of free sugars revealed glucose as the major sugar (3.3 +/- 0.3 mM), and the concentrations of mannose and glucosamine were 0.065 +/- 0.04 and 0.02 +/- 0.001 mM, respectively. Radiolabeled E. coli bound three vaginal fluid glycoproteins with the following molecular masses and pIs: 82 kDa and pI 5.5, 55 kDa and pI 4.5, and 55 kDa and pI 6.5. The binding was inhibited by mannose and by deglycosylation of the proteins prior to the overlay assay. One of these putative receptors was identified to be the heavy chain of secretory IgA (S-IgA). These data suggest that the free mannose in the fluid is less than that required to affect E. coli-epithelial cell binding interactions and that S-IgA may bind E. coli in the vaginal introitus.

Haemosuccus pancreaticus due to mucinous cystadenocarcinoma: the significance of recurrent abdominal pain, hyperamylasaemia and a pancreatic cyst in association with recurrent gastrointestinal bleeding

Haemosuccus pancreaticus is a rare cause of gastrointestinal haemorrhage, and when it presents in otherwise healthy people, can prove difficult to diagnose. The cardinal features are episodic epigastric pain associated with a raised serum amylase and the passage of melaena. Failure to make the connection between recurrent gastrointestinal bleeding and apparently unrelated symptoms attributable to pancreatitis may lead to a significant delay in diagnosis.

Preliminary clinical results of a biphasic waveform and an RV lead system

Biphasic defibrillation waveforms have provided a reduction in defibrillation thresholds in transvenous ICD systems. Although a variety of biphasic waveforms have been tested, the optimal pulse durations and tilts have yet to be identified. A multicenter clinical study was conducted to evaluate the performance of a new ICD biphasic waveform and new RV active fixation steroid eluting lead system. Fifty-three patients were entered into the study. Mean age was 63 years with a mean ejection fraction of 36.8%. Primary indication for implantation was monomorphic ventricular tachycardia alone (54.7%). Forty-eight patients (90.6%) were implanted with an RV shocking lead and active can alone as the anodal contact. The ICD can was the cathode. In four cases (7.5%), an additional SVC or CS lead was used due to a high DFT with the RV lead alone. In an additional case, a chronic SVC lead was used although the RV-Can DFT was acceptable. DFT for all cases at implant was 9.8 +/- 3.7 J. Repeat testing at 3 months for a subset of patients showed a reduction in DFT (7.4 +/- 3.0 J), P value = 0.03. Sensing and pacing characteristics of the RV lead system remained excellent during the study period (acute 0.047 +/- 0.005 ms at 5.4 V and 9.9 +/- 6.2 mV R wave; chronic 0.067 +/- 0.11 ms at 5.4 V and 9.3 +/- 5.4 mV R wave). It is concluded that this lead system provides good acute and chronic sensing and pacing characteristics with good DFT values in combination with this waveform.

Intraorifice sealing of gutta-percha obturated root canals to prevent coronal microleakage

A study was conducted to evaluate Cavit, Intermediate Restorative Material, and Super-EBA as intraorifice filling materials to prevent coronal microleakage. Root canal instrumentation and obturation was done on 74 extracted single-rooted teeth. Three and one-half millimeters of the gutta-percha was removed from the coronal aspect of the root canal and replaced with one of the three filling materials. The teeth were suspended in scintillation vials containing trypticase soy broth, and human saliva was added to the pulp chambers. Microbial penetration was detected as an increase in turbidity of the broth corresponding to bacterial growth. At the end of 90 days, the results showed that 15% of the Cavit-filled orifices leaked, whereas 35% of the Intermediate Restorative Material and Super-EBA-filled orifices leaked. The gutta-percha obturated root canals that received an intraorifice filling material leaked significantly less than the obturated, unsealed control group--all of which leaked in < 49 days.

Complex limbal choristomas in linear nevus sebaceous syndrome

OBJECTIVE

This study aimed to describe the clinical and histopathologic findings in four patients with complex limbal choristomas associated with linear nevus sebaceous syndrome (LNSS), a rare disorder including nevus sebaceous, seizures, and mental retardation, and often accompanied by ocular anomalies.

DESIGN

Small observational case series.

METHODS

A retrospective review of the clinical and histopathologic records of four patients.

RESULTS

Each of four patients had complex limbal choristomas in the setting of clinical and histopathologic LNSS. The limbal choristomas were multiple in three patients and bilateral in two patients. Most choristomas involved the superotemporal limbus (6 of 10), although nasal (3 of 10) and inferior (1 of 10) limbal tumors also were present. Three patients had significant corneal astigmatism or involvement of the central cornea requiring surgical removal of their choristomas, one accompanied by a lamellar keratoplasty and another accompanied by two consecutive penetrating keratoplasties. Each graft eventually vascularized, reducing vision. One patient's vision was limited by amblyopia and another by occipital cortical dysgenesis with visual impairment. Histopathologic examination of the excised choristomas showed foci of lacrimal gland (3 of 4 patients), adipose tissue (3 of 4), neural tissue (1 of 4), cartilage (1 of 4), lymphoid follicles (1 of 4), skin adnexal tissue (1 of 4), and smooth muscle (1 of 4). Other associated ocular findings included an eyelid mass (1 of 4), colobomas of the eyelid (3 of 4), colobomas of the choroid and retina (2 of 4), nonparalytic strabismus (2 of 4), scleral ectasia (1 of 4), partial oculomotor palsy with ptosis and anisocoria (1 of 4), microphthalmia (1 of 4), hypertelorism (1 of 4), and cortical visual impairment (1 of 4).

CONCLUSIONS

Complex limbal choristomas, although rare, can occur in the setting of LNSS and can be associated with multiple ocular and systemic abnormalities. Visual prognosis appears poor in most cases despite aggressive management.

Image-guided core-needle breast biopsy is an accurate technique to evaluate patients with nonpalpable imaging abnormalities

OBJECTIVE

The goal was to evaluate one institution's experience with image-guided core-needle breast biopsy (IGCNBB) and compare the pathologic results with wire-localized excisional breast biopsy (WLEBB) for patients with positive cores and the mammographic surveillance results for patients with negative cores.

SUMMARY BACKGROUND DATA

IGCNBB is becoming a popular, minimally invasive alternative to WLEBB in the evaluation of patients with nonpalpable abnormalities.

METHODS

This study includes all patients with nonpalpable breast imaging abnormalities evaluated by IGCNBB from July 1993 to February 1997. Patients with positive cores (atypical hyperplasia, carcinoma in situ, or invasive carcinoma) were evaluated by WLEBB. Patients with negative cores (benign histology) were followed with a standard mammographic protocol. IGCNBB results were compared with WLEBB results to determine the sensitivity and specificity for each IGCNBB pathologic diagnosis.

RESULTS

Of 1440 IGCNBBs performed during the study period, 1106 were classified as benign, and during surveillance follow-up only a single patient was demonstrated to have a carcinoma in the index part of the breast evaluated by IGCNBB (97.3% sensitivity, 99.7% specificity). IGCNBB demonstrated atypical hyperplasia in 72 patients, 5 of whom refused WLEBB. The remaining 67 patients were evaluated by WLEBB: nonmalignant findings were found in 31, carcinoma in situ was found in 25, and invasive carcinoma was found in 11 (100% sensitivity, 88.8% specificity). IGCNBB demonstrated carcinoma in situ in 84 patients; WLEBB confirmed carcinoma in situ in 54 and invasive carcinoma in 30 (65.4% sensitivity, 97.7% specificity). IGCNBB demonstrated invasive carcinoma in 178 patients. Three were lost to follow-up. On WLEBB, 173 of the remaining 175 had invasive carcinoma; the other 2 patients had carcinoma in situ (80.8% sensitivity, 99.8% specificity).

CONCLUSIONS

An IGCNBB that demonstrates atypical hyperplasia or carcinoma in situ requires WLEBB to define the extent of breast pathology. Mammographic surveillance for a patient with a benign IGCNBB is supported by nearly 100% specificity. An IGCNBB diagnosis of invasive carcinoma is also associated with nearly 100% specificity; therefore, these patients can have definitive surgical therapy, including axillary dissection or mastectomy, without waiting for the pathologic results of a WLEBB. Based on the authors' findings, IGCNBB can safely replace WLEBB in evaluating patients with nonpalpable breast abnormalities.

Experimental study of tetrodotoxin, a long-acting topical anesthetic

PURPOSE

To determine the effectiveness and toxicity of tetrodotoxin for use as a long-acting topical anesthetic.

METHODS

Four groups of six rabbits each received a 40-microl aliquot of either tetrodotoxin in one of three concentrations (10 mM, 1 mM, or 0.1 mM) or proparacaine 0.5% into the inferior conjunctival cul-de-sac of one eye, with the fellow eye of each rabbit receiving 40 microl of a 60-mM, pH 4.3 sodium citrate vehicle as a control. Corneal sensation was tested for up to 8 hours after administration of drugs, and response was noted by no blink, partial blink without full eyelid closure, and full blink. Slit-lamp examination at 12 and 24 hours after administration and pachymetry before and 24 hours after administration were performed to detect corneal toxicity.

RESULTS

Rabbits receiving all three concentrations of tetrodotoxin did not demonstrate any ocular irritation, corneal thickening, or signs of systemic toxicity. At a dose of 10 mM, tetrodotoxin produced an anesthetic effect lasting up to 8 hours. At 1 mM, tetrodotoxin was an effective but shorter-acting anesthetic. At 0.1 mM, tetrodotoxin had no significant anesthetic effect. Proparacaine-treated rabbits initially were anesthetic, but this effect was largely gone by 1 hour and completely gone by 3 hours.

CONCLUSIONS

Tetrodotoxin is a long-acting topical anesthetic in the rabbit cornea. Although additional toxicity studies are required, tetrodotoxin may provide an effective, long-lasting topical anesthetic for use in pain control after corneal procedures such as photorefractive keratectomy.

Elimination of mucosal cyathostome larvae by five daily treatments with fenbendazole

The efficacy of five daily treatments with 7.5 mg fenbendazole/kg bodyweight against mucosal cyathostome larvae was evaluated in 20 12- and 24-month-old ponies with naturally acquired cyathostome infections. After three weeks communal grazing on infected pasture and six weeks indoors, one group of 10 ponies were treated. Six weeks later, both groups of ponies were humanely destroyed and their burdens of large intestinal cyathostome worms, including luminal parasites and mucosal larvae, were assessed. In the control animals approximately 7 per cent of the total worm burden was present in the gut lumen and 93 per cent was present as larvae in the large intestinal mucosa. The efficacy of fenbendazole against the luminal cyathostomes was 90.7 per cent (P < 0.01). The total numbers of mucosal larvae, recovered after digestion, were reduced by 95.3 per cent (P < 0.0005); mucosal late third and fourth stage larvae were reduced by 99.4 per cent (P < 0.0001), and early inhibited third stage larvae by 91.5 per cent (P < 0.005).

Experimental use of tetrodotoxin for corneal pain after excimer laser keratectomy

PURPOSE

To determine the duration of anesthesia, effect on corneal reepithelialization, and systemic toxicity of topical tetrodotoxin (TTX) administered after excimer laser keratectomy.

METHODS

Two groups of six rabbits each underwent excimer laser keratectomy in the right eye to create a 5-mm-diameter wound, 75 mm in depth. One group then received a 40-microl aliquot of topical 1 mM TTX into the injured eye, whereas the other group received 40 microl of the sodium citrate vehicle as a control. The rabbits were treated with TTX or vehicle again at 6, 12, 18, and 24 h. Corneal sensation was tested at 3, 6, 9, 12, 15, 18, 21, 24, 30, 32, and 40 h. To determine whether TTX inhibited corneal reepithelialization, compared with vehicle-treated control eyes, the healing rate of the epithelial defect was measured.

RESULTS

Administration of TTX every 6 h for 24 h produced nearly complete anesthesia for > or = 30 h. At 32 h, 8 h after the final application of TTX, there was still significant anesthesia of the TTX-treated corneas (p = 0.0325, Wilcoxon test). Normal corneal sensation in all TTX-treated animals returned at 40 h, or 16 h after the final dose. In contrast, vehicle-treated eyes all had normal sensation for nearly the entire duration of the experiment. At 40 h, the TTX-treated eyes had slightly larger defects than vehicle-treated eyes, 7.85+/-1.74 versus 4.54+/-1.31 mm2 (p < 0.025, t test). However, at 49 h and thereafter, both groups were equally healed (p > 0.05, t test). No systemic toxicity was observed in any of the rabbits.

CONCLUSION

Topical TTX is a long-acting and nontoxic local anesthetic in a rabbit model of excimer laser keratectomy.

The influence of dietary supplementation with urea on resilience and resistance to infection with Haemonchus contortus

Previous research has indicated that supplementing an apparently adequate diet with additional protein improves both host resistance and resilience in lambs infected with Haemonchus contortus. The present study tested the influence of supplementation with non-protein nitrogen (urea). Helminth-naive Hampshire Down lambs were given an apparently adequate basal diet or a diet supplemented with urea. The lambs were then infected with Haemonchus contortus for 10 weeks. Supplementation with urea had no discernible effect on resistance to infection; faecal egg counts, worm burdens, worm lengths and mean number of eggs per adult female worm did not differ between the 2 groups. However, lambs on the supplemented diet showed better resilience; they had greater packed red cell volumes, higher plasma albumin concentrations and increased liveweight gain compared to lambs on the basal diet. The loss of appetite following infection was less in lambs fed the urea-supplemented diet. The observed effect of urea supplementation was seemingly due to greater food consumption as well as the better diet.

The genetic basis of resistance to Ostertagia circumcincta in lambs

The relationship between Ostertagia (Teladorsagia) circumcincta and sheep is one of the best understood host-parasite relationships in any species. The key components of resistance have been quantified, the extent of genetic control has been established for lambs, and methods now exist to breed lambs which will be both more resistant to worms and more productive than unselected lambs. A major gene for resistance has been identified within or around the major histocompatibility complex, and this gene appears to be the strongest yet identified for resistance to any parasite species. The most important mechanisms of resistance are local IgA responses which regulate worm fecundity and immediate hypersensitivity responses which regulate worm burdens. IgA responses develop before effective immediate hypersensitivity responses. Good simulation models now exist to predict, for example, outbreaks of disease and the response of sheep to selection. The challenge now is to use our improved understanding of the population biology to develop even better simulation models and to produce expert systems based on these models which can be used by veterinarians and others to determine optimal procedures for individual farms to control disease and reduce sub-clinical economic losses.

Response to artificial and subsequent natural infection with Haemonchus contortus in red Maasai and Dorper ewes

Maiden Red Maasai and Dorper ewes were kept indoors and artificially infected with a single oral dose of 5000 infective larvae of Haemonchus contortus. Their faecal egg counts (FEC) and packed red cell volumes (PCV) were monitored for 9 weeks. They were then treated with an anthelmintic and turned out to graze together on a pasture contaminated with H. contortus. They grazed this pasture for 14 months and were allowed to mate and lamb. While at pasture the ewes were monitored for FEC, PCV and peripheral eosinophilia. Red Maasai ewes had significantly lower FEC, and for certain periods, significantly higher PCV and peripheral eosinophilia. During the periparturient period, FEC were about twice as high in the Dorper breed as the Red Maasai. These results confirm and extend previous reports on the superiority of the Red Maasai breed in East Africa.