Prevalence and distribution of pathogen infection and permethrin resistance in tropical and temperate populations of Rhipicephalus sanguineus s.l. collected worldwide.

The brown dog tick, Rhipicephalus sanguineus sensu lato (s.l.) Latreille (Acari: Ixodidae), is a peridomestic, cosmopolitan parasite of dogs known to vector numerous pathogens of veterinary and medical importance. Recent phylogenetic analyses separate this tick into temperate and tropical lineages. Populations of Rh. sanguineus s.l. have been reported to exhibit sodium channel target site insensitivity to permethrin and etofenprox, which is likely due to the prolonged use of pyrethroids against many pests in and around the home. In this study, populations collected in the Caribbean, Africa, Asia, Europe and North America, were tested to identify the distribution of a known resistance mechanism, pathogen-vector interactions and phylogeny in relation to latitude. Using molecular assays, populations from 29 distinct locations were simultaneously geographically typed and screened for bacterial infection by Rickettsia, Ehrlichia, Babesia and Hepatozoon species, and for the presence of a sodium channel single nucleotide polymorphism known to confer permethrin resistance. Implications of these results on Rh. sanguineus s.l. management in association with geographical distribution will be discussed.

Electrostatic interactions regulate the release of small molecules from supramolecular hydrogels.

Supramolecular hydrogels have great potential as biomaterials for sustained delivery of therapeutics. While peptide-based supramolecular hydrogels have been developed that show promise for drug delivery applications, the high cost of production has limited their widespread adoption. Low molecular weight (LMW) supramolecular hydrogels are emerging as attractive and inexpensive alternatives to peptide-based hydrogels. We recently reported novel cationic fluorenylmethyloxycarbonyl-modified phenylalanine (Fmoc-Phe) hydrogels for localized and sustained in vivo release of an anti-inflammatory agent for functional pain remediation. In an effort to further elucidate design principles to optimize these materials for delivery of a variety of molecular agents, we herein report a systematic examination of electrostatic effects on the release of cargo molecules from Fmoc-Phe derived hydrogels. Specifically, we interrogate the release of cationic, anionic, and neutral cargo molecules from a series of cationic and anionic Fmoc-Phe derived hydrogels. We observed that cargo was readily released from the hydrogels except when the cargo and hydrogel network had complementary charges, in which case the cargo was highly retained in the network. These results demonstrate that the electrostatic characteristics of both the hydrogel network and the specific cargo are critical design parameters in the formulation of LMW supramolecular hydrogel systems in the development of next-generation materials for drug delivery applications.

Thermal, mechanical and viscoelastic properties of citric acid-crosslinked starch/cellulose composite foams.

In this work, biodegradable starch/cellulose composite foams were fabricated at 220 °C by compression moulding gelatinised starch containing cellulose fibres as a reinforcing agent and citric acid as a cross-linking agent. It was found that the stiffness, tensile strength, flexural strength, and hydrophobicity of the starch/cellulose composite foams increased, and water absorption capacity decreased with an increase in the concentration of citric acid. The tensile strength increased from 1.76 MPa for 0 % citric acid to 2.25 MPa for the starch/cellulose composite foam crosslinked with 5 % (w/w) citric acid. Similarly, the flexural modulus also increased from 445 MPa to 601.1 MPa, and the flexural strength from 3.76 MPa to 7.61 MPa, for the composite foam crosslinked with 5 % (w/w) citric acid. The crosslinked composite foams showed better thermal stability compared to the non-crosslinked composite foam. The resulting composite foams could be used as a biodegradable alternative to expanded polystyrene packaging.

Identification and characterisation of Staphylococcus aureus on low cost screen printed carbon electrodes using impedance spectroscopy.

Staphylococcus aureus infections are a cause of significant morbidity and mortality, in addition to representing a considerable economic burden. The aim of this study was to explore a low cost screen printed electrode as a sensor for the detection of S. aureus using impedance spectroscopy. S. aureus was incubated in chambers containing the electrodes and the results analysed using a novel normalisation approach. These results show that it is possible to detect the presence of S. aureus in LB media after 30 min incubation of a 1% growth culture, in addition to being able to see immediate cell concentration dependant changes in 0.9% NaCl. These observations imply that a number of electrochemical mechanisms cause a change in the impedance as a result of the presence of S. aureus, including adsorption to the electrode surface and the metabolism of the bacteria during growth. The study suggests that this detection approach would be useful in a number of clinical scenarios where S. aureus leads to difficult to treat infections.

Diverse clinical phenotypes associated with a nonsense mutation in FAM161A.

PURPOSE: Mutations in the FAM161A gene have been reported in association with autosomal recessive retinitis pigmentosa (arRP) in several ethnic populations. This study aimed to assess the prevalence of FAM161A-related retinopathy in a British cohort and to characterise the phenotype associated with mutations in this gene. METHODS: The FAM161A coding region and intron-exon boundaries were screened by Sanger sequencing in 120 retinitis pigmentosa (RP) patients (with likely autosomal recessive inheritance) in whom mutations in other known major RP genes have been ruled out by commercially available testing. Homozygosity mapping was performed in one consanguineous family, and high-throughput sequencing of candidate genes was performed to identify disease-associated changes. Clinical assessment of affected individuals included perimetry testing, fundus autofluorescence imaging, and optical coherence tomography. RESULTS: Two patients of British origin with a homozygous mutation in FAM161A (c.1309A>T, p.Arg437*) were identified by Sanger sequencing. Homozygosity mapping and subsequent high-throughput sequencing analysis identified a further family of Pakistani origin with the same genotype. Clinical examination of affected members of these families revealed that this mutation was associated with a diverse clinical phenotype, ranging from mild disease with preservation of central acuity to severe visual impairment. CONCLUSIONS: Homozygosity for the c.1309A>T, p.Arg437* variant in FAM161A is a relatively common cause of arRP. The mutation occurs in diverse ethnic populations, associated with typical retinitis pigmentosa with disease onset usually in the second or third decade of life.

Minimally invasive surgical techniques in the management of differentiated thyroid cancer.

Thyroid cancer is the fifth most common cancer in women with approximately 60,220 expected new cases in the United States in 2013, and the incidence continues to increase each year. Fortunately, the majority are well-differentiated thyroid cancers with excellent overall prognosis. Controversy persists regarding the optimal surgical management of differentiated thyroid cancer in terms of the extent of thyroid resection (thyroid lobectomy vs total thyroidectomy) and the utility of prophylactic central neck dissection (pCND) in low-risk PTC, and papillary thyroid microcarcinoma (PTMC, defined as <10 mm). Thyroid surgical approaches have progressed from the Kocher open incision to minimally invasive techniques that include endoscopic and robotic thyroidectomy. Overall, these minimally invasive techniques have been shown to be safe, and appear to be associated with improved cosmesis and decreased pain compared to open thyroidectomy.

Mechanism of transcriptional regulation by the Escherichia coli nitric oxide sensor NorR.

Nitric oxide (NO) is a highly reactive water-soluble gas encountered by bacteria endogenously as an intermediate of denitrification and exogenously as one of the radical species deployed by macrophages against invading pathogens. Bacteria therefore require a mechanism to detoxify NO. Escherichia coli flavorubredoxin and its associated oxidoreductase, encoded by the norV and norW genes respectively, reduces NO to nitrous oxide under anaerobic conditions. Transcription of the norVW genes is activated in response to NO by the sigma(54)-dependent regulator NorR, a member of the prokaryotic enhancer binding protein family. NorR binds co-operatively to three enhancer sites to regulate transcription of both norVW and the divergently transcribed norR gene. In the present paper, we show that disruption of any one of the three GT-(N(7))-AC NorR binding sites in the norR-norVW intergenic region prevents both activation of norVW expression and autogenous repression of the norR promoter by NorR. We have recently demonstrated that the N-terminal GAF (cGMP-specific and -stimulated phosphodiesterases, Anabaena adenylate cyclases and Escherichia coli FhlA) domain of NorR contains a non-haem mononuclear iron centre and senses NO by formation of a mono-nitrosyl iron complex. Site-directed mutagenesis has identified candidate protein ligands to the ferrous iron centre in the GAF domain.

DNA binding properties of the Escherichia coli nitric oxide sensor NorR: towards an understanding of the regulation of flavorubredoxin expression.

Nitric oxide is an intermediate of denitrification, and is one of the radical species deployed by macrophages against invading pathogens, therefore bacterial responses to NO are of considerable importance. The Escherichia coli flavorubredoxin and its associated oxidoreductase reduce NO to nitrous oxide under anaerobic conditions, and are encoded by the norVW transcription unit. Expression of norVW requires the NO sensing regulatory protein NorR and is dependent on RNA polymerase containing the alternative sigma factor, sigma(54). We have purified NorR and shown that it binds to three sites in the norVW promoter region, located 75-140 bp upstream of the experimentally verified transcription start site. We have also identified two binding sites for the integration host factor, one between the NorR sites and the sigma(54)-RNA polymerase binding site, and a second downstream of the norVW transcription start site. Comparison of the norVW promoters of enteric bacteria along with known and putative NorR-regulated promoters from Vibrio, Ralstonia and Pseudomonas species suggests that NorR binding sites contain an invariant GT(N7)AC motif flanking an AT-rich central region. The identification of a consensus for NorR binding sites will help to elucidate additional members of the NorR regulon.

Failure of the conjugate pneumococcal vaccine to prevent recurrent bacteremia in a child with human immunodeficiency virus disease.

Patients with advanced HIV disease have a poor response to some immunizations. A case is presented of a Class C1 HIV-infected child who suffered three episodes of Streptococcus pneumoniae serotype 6B bacteremia despite having received the heptavalent conjugate and 23-valent polysaccharide pneumococcal vaccines. Clinicians should expect some vaccine failures with the heptavalent conjugate vaccine in children with advanced HIV disease.

Invasive pneumococcal infections in pediatric cardiac transplant patients.

BACKGROUND: Bacterial infections cause significant morbidity and mortality in cardiac transplant patients. Because Streptococcus pneumoniae is the most prominent bacterial pathogen of childhood, the objective of this study was to define the role of S. pneumoniae as a pathogen in the cardiac transplant population. METHODS: Medical records of cardiac transplant patients from March, 1990, through November, 2000, were reviewed to identify invasive pneumococcal infections after transplantation. Demographic, clinical and microbiologic data were reviewed. RESULTS: Nine (11%) of 80 patients had 12 episodes of pneumococcal bacteremia for an incidence rate of 39 cases/1,000 patient years. Patients who were African-American, transplanted before 2 years of age and transplanted because of idiopathic dilated cardiomyopathy were at increased risk of invasive pneumococcal disease (P < 0.05). Six patients were eligible for the 23-valent pneumococcal polysaccharide vaccine before their first invasive infection, but only 1 had received it at the recommended age. Most isolates (82%) were penicillin-susceptible, and no single serotype predominated. There were 2 deaths in the study group, but each was unrelated to infection. Three patients (33%) had recurrent invasive disease with a second serotype an average of 12 months after the first infection. CONCLUSIONS: The incidence of pneumococcal bacteremia in cardiac transplant patients is higher than in the general pediatric population. Risks for infection were being African-American, being younger than 2 years at the time of transplant and being transplanted because of idiopathic cardiomyopathy. It is plausible that pneumococcal vaccine would decrease this risk.

Resolution of natural groups using iterative assignment tests: an example from two species of Australian native rats (Rattus).

Sympatric individuals of Rattus fuscipes and Rattus leucopus, two Australian native rats from the tropical wet forests of north Queensland, are difficult to distinguish morphologically and are often confused in the field. When we started a study on fine-scale movements of these species, using microsatellite markers, we found that the species as identified in the field did not form coherent genetic groups. In this study, we examined the potential of an iterative process of genetic assignment to separate specimens from distinct (e.g. species, populations) natural groups. Five loci with extensive overlap in allele distributions between species were used for the iterative process. Samples were randomly distributed into two starting groups of equal size and then subjected to the test. At each iteration, misassigned samples switched groups, and the output groups from a given round of assignment formed the input groups for the next round. All samples were assigned correctly on the 10th iteration, in which two genetic groups were clearly separated. Mitochondrial DNA sequences were obtained from samples from each genetic group identified by assignment, together with those of museum voucher specimens, to assess which species corresponded to which genetic group. The iterative procedure was also used to resolve groups within species, adequately separating the genetically identified R. leucopus from our two sampling sites. These results show that the iterative assignment process can correctly differentiate samples into their appropriate natural groups when diagnostic genetic markers are not available, which allowed us to resolve accurately the two R. leucopus and R. fuscipes species. Our approach provides an analytical tool that may be applicable to a broad variety of situations where genetic groups need to be resolved.

Prevention of perinatal transmission of HIV in Arkansas.

In 1994, the Centers for Disease Control and Prevention (CDC) recommended zidovudine (ZDV) prophylaxis to reduce perinatal transmission of HIV. Caregivers at the University of Arkansas for Medical Sciences (UAMS) instituted a program of universal voluntary HIV testing of pregnant females combined with maternal education regarding ZDV prophylaxis in October 1994. Since that time, 7 of 39 (18%) infants referred to Arkansas Children's Hospital (ACH) for evaluation of perinatal HIV exposure have been infected compared to 21 of 53 (40%) referred prior to October 1994, (p = 0.042). Unfortunately, of the 39 infants referred to ACH after October 1994, 21 were born to HIV-infected mothers who did not comply with prophylaxis. Fifteen of these mothers were not offered intravenous ZDV during delivery; five have children infected with HIV. These data indicate the need for increased efforts by health officials in Arkansas to institute nationally recommended methods of prevention of perinatal HIV.

Clinically suspected primary acquired nasolacrimal duct obstruction: clinicopathologic review of 150 patients.

PURPOSE: The incidence of lacrimal sac pathology in patients with clinically suspected primary acquired nasolacrimal duct obstruction is unknown. This is an important issue when considering the potential risk of either conservative nonsurgical management or laser dacryocystorhinostomy, neither of which permits direct visualization and biopsy of the lacrimal outflow apparatus. METHODS: A total of 162 lacrimal sac biopsy specimens were obtained in 150 consecutive patients undergoing external or endonasal dacryocystorhinostomy for clinical primary acquired nasolacrimal duct obstruction from January 1992 to October 1994. RESULTS: A total of 147 patients (98%) had histopathologic findings consistent with inflammation or fibrosis of the lacrimal sac or both. In the remaining three patients, abnormalities included sarcoid granuloma (one patient), oncocytoma (one patient), and lymphoma (one patient). CONCLUSIONS: The incidence of significant pathology of the lacrimal sac in clinically suspected primary acquired nasolacrimal duct obstruction is low. However, these cases can be identified correctly only by routine biopsy of the lacrimal sac during dacryocystorhinostomy.

Thymic carcinoma metastatic to the orbit.

PURPOSE: To report a case of small cell carcinoma of the thymus metastatic to the orbit. METHODS: At age 37 years, a man who had been previously diagnosed and treated for small cell carcinoma of the thymus was initially examined for vertical diplopia and left proptosis. Computed tomographic scan disclosed a soft tissue mass in the superior aspect of the left orbit. A fine-needle aspiration biopsy of the mass was performed and submitted for cytopathologic examination. RESULT: The cytopathology and immunopathology disclosed malignant cells consistent with metastatic small cell thymic carcinoma. CONCLUSION: This is the first reported case of a primary thymus gland tumor metastatic to the orbit.

The anatomy of the common canaliculus.

BACKGROUND: The functional valve between the common canaliculus and the lacrimal sac has traditionally been attributed to the valve of Rosenmüller, although this anatomical structure has never been rigorously documented. OBJECTIVE: To define the anatomy of the canaliculus-sac junction. METHODS: Twelve rigid plastic casts of the lacrimal outflow systems were obtained in human cadaver specimens using a well-known biologic casting material (partially polkymerized monomer to which a catalyst and promoter were added). RESULTS: A consistent pattern of angulation within the canalicular system was documented. The canaliculi bend posteriorly behind the medial canthal tendon, then anteriorly to enter the sac at an acute mean angle of 58 degrees to the lateral wall of the sac. CONCLUSIONS: This consistent configuration at the canaliculus-sac junction has not been previously described and may contribute to the 1-way valve phenomenon seen in some lacrimal disorders.

The anatomy of Whitnall ligament.

BACKGROUND: The current understanding of the anatomy of Whitnall ligament does not explain its functional role in eyelid movement. This anatomic study was designed to determine the exact relation of Whitnall ligament to the levator muscle and aponeurosis. METHODS: The anatomy of the eyelid was examined by surgical dissection of 20 eyelids undergoing Müllerectomy via a conjunctival approach, anatomic dissection of 20 fresh cadaver orbits, and histologic correlation in four fresh specimens. RESULTS: Whitnall ligament is a sleeve of fibrous tissue with both a superior and inferior component which join medially and laterally before inserting onto the bony orbit. CONCLUSIONS: The authors postulate that this sleeve acts as a mobile fulcrum straddling the underneath surface of the levator aponeurosis and functions to convert the anterior-posterior vector force of the levator to a superior-inferior direction during eyelid movement. This model proposes that when the levator is relaxed, Whitnall sleeve hangs down, allowing the lid to close. When the muscle contracts, the sleeve along with the levator aponeurosis is lifted superiorly in the orbit, enhancing the lifting effect of levator muscle contraction in eyelid elevation.

Photoemission Study of CO Adsorption on Gd.

Angle-resolved UV photoemission spectroscopy has been used to investigate the interaction of CO with Gd films, grown on W(110). The results suggest the CO absorbs dissociatively, initially forming Gd(2)O(3), with subsequent catalytic oxidation of CO to form carbonate.

Efficacy of unanesthetized spiral computed tomography scanning in initial evaluation of childhood leukocoria.

PURPOSE: To evaluate the use of spiral/helical computed tomography (CT) in the preoperative evaluation of pediatric leukocoria. METHODS: A total of 34 patient charts and imaging studies were reviewed from a consecutive series of children referred with the diagnosis of presumed retinoblastoma. Of these patients, 31 had a confirmed diagnosis of retinoblastoma. Three patients had simulating lesions, including one patient with persistent hyperplastic primary vitreous and two with Coats disease. RESULTS: In all patients, a diagnosis of intraocular retinoblastoma could be established or excluded at the same clinical level by spiral CT as by conventional CT. Spiral CT of the eye, orbit, and midline structures was performed without a requirement for patient anesthesia. This technique resulted in a reduced volume of contrast material required for evaluation of the central nervous system and a small decrease in total radiation exposure. There was an attendant reduction in the amount of monitoring equipment required and the necessity for attending anesthesia staff. CONCLUSIONS: The primary advantage of spiral CT is reduced anesthesia risk in small children. In addition, this technique provides necessary clinical information with a reduction in image acquisition time, monitoring equipment, and monitoring staff.