Radiation-induced gastrointestinal fistulae.

Seventy patients with radiation enteritis presented to a single surgical unit between 1958 and 1984. Of these 10 (14%) had 14 radiation-induced fistulae. The median latent period between radiotherapy and presentation of the fistula was 20 months. The fistulae were often multiple and/or associated with other radiation-induced lesions, patients presenting with fistulae being significantly more likely to have synchronous lesions compared with those who presented with strictures (P = 0.005). These patients are often unfit for major surgery. Wide resection and anastomosis, or exclusion operations are the surgical procedures of choice.     

Carcinoid syndrome. Surgical management

Carcinoid syndrome occurs in about five percent of patients with carcinoid tumours. Most of these patients have diffuse liver metastases at the first presentation and the surgical options are few. Medical treatment or hepatic dearterialization achieves a temporary response in most cases. Occasionally, the liver lesions are confined to one anatomical lobe and resection may be feasible.     

Use of calcium alginate to pack abscess cavities: a controlled clinical trial.

Many conventional dressings are painful when removed, and may be detrimental to healing. In a pilot study ten consecutive abscesses, requiring incision and drainage, were packed with a calcium alginate dressing: this was well tolerated, its removal causing minimal pain. No adverse effects were attributable to its use. A controlled trial was therefore carried out to compare calcium alginate with the more traditional saline-soaked gauze for packing abscess cavities, following incision and drainage. Patients were randomized to receive either calcium alginate (16 patients) or gauze dressing (18 patients). At the first dressing change the patient marked on a linear analogue scale the pain experienced; the nurse noted similarly the ease of removal of the dressing. Calcium alginate was significantly less painful to remove after operation (P less than 0.01), and also easier to remove (P less than 0.01) than gauze dressings. If abscess cavities are packed after incision and drainage, calcium alginate appears to be an improvement on conventional dressings.     

Gene conversion is a likely cause of mutation in PKD1

Approximately 70% of the gene responsible for the most common form of autosomal dominant polycystic kidney disease ( PKD1 ) is replicated in several highly homologous copies located more proximally on chromosome 16. We recently have described a novel technique for mutation detection in the duplicated region of PKD1 that circumvents the difficulties posed by these homologs. We have used this method to identify two patients with a nearly identical cluster of base pair substitutions in exon 23. Since pseudogenes are known to be reservoirs for mutation via gene conversion events for a number of other diseases, we decided to test whether these sequence differences in PKD1 could have arisen as a result of this mechanism. Using changes in restriction digest patterns, we were able to show that these sequence substitutions are also present in N23HA, a rodent-human somatic cell hybrid that contains only the PKD1 homologs. Moreover, these changes were also detected in total DNA from several affected and unaffected individuals that did not harbor this mutation in their PKD1 gene copy. This is the first example of gene conversion in PKD1 , and our findings highlight the importance of using gene-specific reagents in defining PKD1 mutations.      

Copolymerization of ethylene with 1-hexene and 1-octene: correlation between type of catalyst and comonomer incorporated

The behaviour of catalytic systems based on zirconium compounds for the copolymerization of ethylene with 1-hexene and 1-octene is reported. The metallocenes (CH₃)₂SiCp₂ZrCl₂, Cp₂ZrCl₂ (Cp = η⁵-cyclopentadienyl), C₂H₄[Ind]₂ZrCl₂ and (Ind = η⁵-indenyl) were chosen for this study. The bridged catalysts, (CH₃)₂SiCp₂ZrCl₂ and C₂H₄[Ind]₂ZrCl₂, and the metallocene Cp₂ZrCl₂ showed similar catalytic activities for home- and copolymerization of ethylene with 1-hexene. ¹³C NMR analysis showed that the composition of copolymerization products depends on the catalytic system, in other words, on the ligand structure of the transition metal. Copolymers obtained using the bridged catalysts have greater incorporation of comonomer. Thermal analysis and viscosity measurements demonstrated that an increase of the comonomer concentration reduces the melting point, the crystallinity and the molecular weight of the copolymer. Results from infrared spectroscopy showed that β-elimination is one of the possible termination reactions. The monomer reactivity ratios r were determined for all catalytic systems using Fineman-Ross and ¹³C NMR methods. The values of r₁ (M₁ = ethylene) and r₂ (M₂ = α-olefin) showed an effect of the type of metallocene and of α-olefin on the structure of the copolymer obtained.     

Carotid duplex imaging: variation and validation

BACKGROUND: Duplex imaging is increasingly used as the only investigation before carotid endarterectomy, but many different criteria exist in the literature for the detection of a severe (70-99 per cent) carotid stenosis. This study aimed to investigate current practice in carotid duplex imaging in Great Britain and Ireland. METHODS: A postal questionnaire was sent to 86 vascular surgical units. RESULTS: The median number of scans performed per year was 450 (range 60-4500). Thirty-six per cent of units who responded used peak systolic : end diastolic velocity ratio to calculate carotid stenosis. Overall, nine different major duplex criteria were used to grade carotid stenosis in 14 different systems of percentage bands. Only 51 per cent of units verified their duplex criteria against angiography. Eighteen per cent of units used two or more different types of duplex scanner and applied the same diagnostic criteria to each machine. CONCLUSION: A wide variation in diagnostic duplex criteria and methods of grading stenosis exists among vascular units. Internal validation is not performed routinely. Standardization of duplex criteria would ensure greater consistency, but would not replace the need for validation of results within each unit.     

Public Health Implications of Changing Rodent Importation Patterns – United States, 1999–2013

The United States imports a large volume of live wild and domestic animal species; these animals pose a demonstrated risk for introduction of zoonotic diseases. Rodents are imported for multiple purposes, including scientific research, zoo exhibits and the pet trade. Current U.S. public health regulatory restrictions specific to rodent importation pertain only to those of African origin. To understand the impacts of these regulations and the potential public health risks of international rodent trade to the United States, we evaluated live rodent import records during 1999–2013 by shipment volume and geographic origin, source (e.g. wild‐caught versus captive‐ or commercially bred), intended purpose and rodent taxonomy. Live rodent imports increased from 2737 animals during 1999 to 173 761 animals during 2013. Increases in both the number and size of shipments contributed to this trend. The proportion of wild‐captured imports declined from 75% during 1999 to <1% during 2013. Nearly all shipments during these years were imported for commercial purposes. Imports from Europe and other countries in North America experienced notable increases in volume. Gerbils and hamsters arriving from Europe and chinchillas, guinea pigs and hamsters arriving from other countries in North America were predominant taxa underlying this trend. After 2003, African‐origin imports became sporadic events under the federal permit process. These patterns suggest development of large‐scale captive rodent breeding markets abroad for commercial sale in the United States. While the shift from wild‐captured imports alleviates many conservation concerns and risks for novel disease emergence, such consolidated sourcing might elevate exposure risks for zoonotic diseases associated with high‐density rodent breeding (e.g. lymphocytic choriomeningitis or salmonellosis). A responsive border health system must periodically re‐evaluate importation regulations in conjunction with key stakeholders to ensure a balance between the economic benefits of rodent trade against the potential public health risks.