Two Forms of Tyrosyl-tRNA Synthetase from Pseudomonas aeruginosa: Characterization and Discovery of Inhibitory Compounds

Pseudomonas aeruginosa is a multidrug-resistant (MDR) pathogen and a causative agent of both nosocomial and community-acquired infections. The genes (tyrS and tyrZ) encoding both forms of P. aeruginosa tyrosyl-tRNA synthetase (TyrRS-S and TyrRS-Z) were cloned and the resulting proteins purified. TyrRS-S and TyrRS-Z were kinetically evaluated and the K_m values for interaction with Tyr, ATP, and tRNA^Tyr were 172, 204, and 1.5 μM and 29, 496, and 1.9 μM, respectively. The k_cat^obs values for interaction with Tyr, ATP, and tRNA^Tyr were calculated to be 3.8, 1.0, and 0.2 s^-1 and 3.1, 3.8, and 1.9 s^-1, respectively. Using scintillation proximity assay (SPA) technology, a druglike 2000-compound library was screened to identify inhibitors of the enzymes. Four compounds (BCD37H06, BCD38C11, BCD49D09, and BCD54B04) were identified with inhibitory activity against TyrRS-S. BCD38C11 also inhibited TyrRS-Z. The IC₅₀ values for BCD37H06, BCD38C11, BCD49D09, and BCD54B04 against TyrRS-S were 24, 71, 65, and 50 μM, respectively, while the IC₅₀ value for BCD38C11 against TyrRS-Z was 241 μM. Minimum inhibitory concentrations (MICs) were determined against a panel of clinically important pathogens. All four compounds were observed to inhibit the growth of cultures of both Gram-positive and Gram-negative bacteria organisms with a bacteriostatic mode of action. When tested against human cell cultures, none of the compounds were toxic at concentrations up to 400 μg/mL. In mechanism of inhibition studies, BCD38C11 and BCD49D09 selectively inhibited TyrRS activity by competing with ATP for binding. BCD37H06 and BCD54B04 inhibited TyrRS activity by a mechanism other than substrate competition.

Glutaminyl-tRNA Synthetase from Pseudomonas aeruginosa: Characterization, structure, and development as a screening platform

Pseudomonas aeruginosa has a high potential for developing resistance to multiple antibiotics. The gene (glnS) encoding glutaminyl-tRNA synthetase (GlnRS) from P. aeruginosa was cloned and the resulting protein characterized. GlnRS was kinetically evaluated and the K_M and k_cat ^obs , governing interactions with tRNA, were 1.0 μM and 0.15 s^-1 , respectively. The crystal structure of the α₂ form of P. aeruginosa GlnRS was solved to 1.9 Å resolution. The amino acid sequence and structure of P. aeruginosa GlnRS were analyzed and compared to that of GlnRS from Escherichia coli. Amino acids that interact with ATP, glutamine, and tRNA are well conserved and structure overlays indicate that both GlnRS proteins conform to a similar three-dimensional structure. GlnRS was developed into a screening platform using scintillation proximity assay technology and used to screen ~2,000 chemical compounds. Three inhibitory compounds were identified and analyzed for enzymatic inhibition as well as minimum inhibitory concentrations against clinically relevant bacterial strains. Two of the compounds, BM02E04 and BM04H03, were selected for further studies. These compounds displayed broad-spectrum antibacterial activity and exhibited moderate inhibitory activity against mutant efflux deficient strains of P. aeruginosa and E. coli. Growth of wild-type strains was unaffected, indicating that efflux was likely responsible for the lack of sensitivity. The global mode of action was determined using time-kill kinetics. BM04H03 did not inhibit the growth of human cell cultures at any concentration and BM02E04 only inhibit cultures at the highest concentration tested (400 μg/ml). In conclusion, GlnRS from P. aeruginosa is shown to have a structure similar to that of E. coli GlnRS and two natural product compounds were identified as inhibitors of P. aeruginosa GlnRS with the potential for utility as lead candidates in antibacterial drug development in a time of increased antibiotic resistance.

'The rollercoaster of follow-up care' after bariatric surgery: a rapid review and qualitative synthesis

Benefits of bariatric surgery for obesity related comorbidities are well established. However, in the longer term, patients can become vulnerable to procedure specific problems, experience weight regain and continue to need monitoring and management of comorbidities. Effective longer term follow-up is vital due to these complex needs post-surgery. Current guidance recommends annual long-term follow-up after bariatric surgery. However, attendance can be low, and failure to attend is associated with poorer outcomes. Understanding patients' experiences and needs is central to the delivery of effective care. This rapid review has synthesized the current qualitative literature on patient experiences of healthcare professional (HCP) led follow-up from 12 months after bariatric surgery. A recurring theme was the need for more and extended follow-up care, particularly psychological support. Enablers to attending follow-up care were patient self-efficacy as well as HCP factors such as a non-judgemental attitude, knowledge and continuity of care. Barriers included unrealistic patient expectations and perceived lack of HCP expertise. Some preferences were expressed including patient initiated access to HCPs and more information preoperatively to prepare for potential post-surgery issues. Insights gained from this work will help identify areas for improvement to care in order to optimize longer term outcomes.

Identification and Characterization of Chemical Compounds that Inhibit Leucyl-tRNA Synthetase from Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa is an opportunistic multi-drug resistance pathogen implicated as the causative agent in a high-percentage of nosocomial and community acquired bacterial infections. The gene encoding leucyl-tRNA synthetase (LeuRS) from P. aeruginosa was overexpressed in Escherichia coli and the resulting protein was characterized.

METHODS

LeuRS was kinetically evaluated and the KM values for interactions with leucine, ATP and tRNA were 6.5, 330, and 3.0 μM, respectively. LeuRS was developed into a screening platform using scintillation proximity assay (SPA) technology and used to screen over 2000 synthetic and natural chemical compounds.

RESULTS

The initial screen resulted in the identification of two inhibitory compounds, BT03C09 and BT03E07. IC50s against LeuRS observed for BT03C09 and BT03E07 were 23 and 15 μM, respectively. The minimum inhibitory concentrations (MIC) were determined against nine clinically relevant bacterial strains. In time-kill kinetic analysis, BT03C09 was observed to inhibit bacterial growth in a bacteriostatic manner, while BT03E07 acted as a bactericidal agent. Neither compound competed with leucine or ATP for binding LeuRS. Limited inhibition was observed in aminoacylation assays with the human mitochondrial form of LeuRS, however when tested in cultures of human cell line, BT03C09 was toxic at all concentration whereas BT03E07 only showed toxic effects at elevated concentrations.

CONCLUSION

Two compounds were identified as inhibitors of LeuRS in a screen of over 2000 natural and synthetic compounds. After characterization one compound (BT03E07) exhibited broad spectrum antibacterial activity while maintaining low toxicity against human mitochondrial LeuRS as well as against human cell cultures.

Pediatric trans-oral submandibular gland excision: A safe and effective technique

INTRODUCTION

In the pediatric population the submandibular gland requires removal in a number of conditions including, refractory recurrent sialoadenitis, sialolithiasis, salivary gland neoplasms and debilitating sialorrhea. In comparison to the traditional trans-cervical approach, the trans-oral route avoids a cervical scar, potential keloid formation and decreased risk of injury to the marginal mandibular branch of the facial nerve. This approach also eliminates the potentiality of remnant duct disease since the entire duct and papillae are removed. The article demonstrates the appropriateness of this method in the pediatric population and discusses the anatomy and technique.

METHODS

Retrospective review of ten pediatric patients who underwent trans-oral submandibular gland excision, the series was analyzed for age, gender, indication for procedure, complications, length of hospitalization, and postoperative pathology. Patients were followed for a minimum of 12 months.

RESULTS

7 females and 3 males aged 9 to 17 underwent the procedure. Recurrent sialoadenitis, and sialolithiasis, accounted for 6 cases while salivary neoplasms (pleomorphic adenoma) accounted for 4 cases. No patient suffered vessel or nerve injury and no patient showed recurrent disease at 12 months follow-up. All glands were completely removed and no patient required conversion to the trans-cervical approach.

CONCLUSIONS

Trans-oral submandibular gland excision is safe and effective in the pediatric population. This method avoids a cervical scar, avoids injury to the marginal mandibular branch of the facial nerve, and completely removes the duct, eliminating the potentiality of remnant duct disease. The authors have performed ten trans-oral submandibular gland excisions in pediatric patients without complications.

Unilateral True Vocal Fold Paralysis: Cause of Right-Sided Lesions

At the Georgetown University Center for the Voice, 778 patients were referred for evaluation between July 1, 1990, and June 30, 1995. During this 5-year period, right true vocal fold paralysis or paresis was diagnosed in 24 of these patients (3%). Videostroboscopy, voice analysis, and patient records were reviewed. Ages ranged from 23 to 80 years, and sex distribution approximated a 1:1 ratio. The patients presenting symptoms included hoarseness, dysphagia, choking, voice pitch change, voice weakness, fatigability, and breathiness. Sources of the vocal fold dysfunction included iatrogenic, traumatic, central, and infectious causes.

Evaluation of a multidisciplinary Tier 3 weight management service for adults with morbid obesity, or obesity and comorbidities, based in primary care

A multidisciplinary Tier 3 weight management service in primary care recruited patients with a body mass index ≥40 kg·m(-2) , or 30 kg·m(-2) with obesity-related co-morbidity to a 1-year programme. A cohort of 230 participants was recruited and evaluated using the National Obesity Observatory Standard Evaluation Framework. The primary outcome was weight loss of at least 5% of baseline weight at 12 months. Diet was assessed using the two-item food frequency questionnaire, activity using the General Practice Physical Activity questionnaire and quality of life using the EuroQol-5D-5L questionnaire. A focus group explored the participants' experiences. Baseline mean weight was 124.4 kg and mean body mass index was 44.1 kg·m(-2) . A total of 102 participants achieved 5% weight loss at 12 months. The mean weight loss was 10.2 kg among the 117 participants who completed the 12-month programme. Baseline observation carried forward analysis gave a mean weight loss of 5.9 kg at 12 months. Fruit and vegetable intake, activity level and quality of life all improved. The dropout rate was 14.3% at 6 months and 45.1% at 1 year. Focus group participants described high levels of satisfaction. It was possible to deliver a Tier 3 weight management service for obese patients with complex co-morbidity in a primary care setting with a full multidisciplinary team, which obtained good health outcomes compared with existing services.

Nutritional improvement of the aspartate family of amino acids in edible crop plants

Plants are the primary source of protein for man and livestock, however, not all plants produce proteins which contain a balance of amino acids for the diet to ensure proper growth of livestock and humans. Alteration of the amino acid composition of plants may be accomplished using techniques of molecular biology and genetic engineering. Genes encoding key enzymes regulating the synthesis of lysine and threonine have been cloned from plants andE. coli and are available for modification and transformation into plants. Genes encoding seed storage proteins have been cloned and modified to encode more lysine residues for developing transgenic plants with higher seed lysine. Genes encoding seed storage proteins naturally higher in methionine have been cloned and expressed in transgenic plants, increasing methionine levels of the seed. These and other approaches hold great promise in their application to increasing the content of essential amino acids in plants.

HIV non-occupational postexposure prophylaxis in a Canadian province: treatment completion and follow-up testing

Provincial guidelines for HIV non-occupational postexposure prophylaxis (NPEP) were implemented on January 2005 in Alberta, Canada. Human immunodeficiency virus (HIV) NPEP was provided free of charge following approval by a medical officer of health. Between 1 January 2005 and 30 June 2007, 174 individuals were prescribed NPEP; 135 (78%) were women with a median age of 24 years. Sexual assaults accounted for 68% of exposures. NPEP was completed in 49% of cases. Individuals who completed NPEP were less likely to have been exposed by sexual assault ( P = 0.04) and more likely to have received HIV follow-up testing ( P = 0.03).Individuals who received at least one HIV follow-up test were older ( P = 0.03) and more likely to have been exposed percutaneously ( P = 0.003). Those who received no follow-up testing were less likely to have filled an NPEP prescription ( P = 0.0001). New strategies are required to improve follow-up of individuals receiving NPEP, especially younger persons or sexual assault survivors.

Heterogeneous expression of alpha-methylacyl-CoA racemase in prostatic cancer correlates with Gleason score

AIMS

Alpha-methylacyl-CoA racemase (AMACR) is a sensitive and specific immunohistochemical marker of prostatic malignancy, staining 80-100% of prostatic cancers with absent staining in benign glands. However, positive staining in benign conditions as well as low rates of AMACR reactivity in prostatic cancer variants have been described. Preliminary use of AMACR immunohistochemistry in our institution has suggested lower specificity and sensitivity for prostatic cancer than initially proposed. The aim of this study was to establish true rates of AMACR reactivity in prostatic cancer and benign prostatic hyperplasia (BPH).

METHODS AND RESULTS

AMACR immunohistochemistry was performed on sections from 57 prostatic cancers and 44 BPH resections. Ninety-one percent of cancers were AMACR+, with diffuse (> 75%) tumour staining in 53% of cases. Thirty-eight percent of tumours showed heterogeneous expression (1-75% tumour staining). This was significantly correlated with increased Gleason score. High-grade prostatic intraepithelial neoplasia (PIN) was AMACR+ in 87% of cancers. Eleven percent of BPH showed moderate or strong staining in benign glands, focally mimicking the malignant staining pattern.

CONCLUSIONS

This study confirms heterogeneous AMACR expression in prostatic cancer and shows a correlation with Gleason score. Positive staining in BPH is also documented, thus emphasizing the importance of interpreting AMACR immunohistochemistry in the context of other findings in a diagnostic setting.

Infantile gastroenteritis in the community: a cost-of-illness study

Rotavirus infections are the main cause of gastroenteritis in infants and children and it is expected that by the age of 5 years, nearly every child will have experienced at least one episode of rotavirus gastroenteritis. While severe cases are hospitalized, milder disease is either treated at home or by the GP, and as such the true prevalence of rotavirus infection in the community, and the burden of disease, is unknown. This paper reports the results of a cost-of-illness study which was conducted alongside a structured community surveillance study. Forty-eight percent of our sample was found to have rotavirus acute gastroenteritis; and the average total cost of a child presenting with rotavirus gastroenteritis ranged between pound sterling 59 and pound sterling 143 per episode, depending on the perspective. Given the prevalence and severity of the disease, the estimated burden of rotavirus gastroenteritis to society is pound sterling 11.5 million per year.

Structured surveillance of infantile gastroenteritis in East Anglia, UK: incidence of infection with common viral gastroenteric pathogens

The aim of this study was to investigate the burden of disease associated with gastroenteric viruses (rotavirus, norovirus, sapovirus, astrovirus and enteric adenovirus) using structured surveillance of children aged <6 years in the community. Faecal samples were collected between 2000 and 2003 from 685 children with symptoms of gastroenteritis. The children comprised three groups; 223 in the structured surveillance cohort, 203 in a community cohort and 259 in a cohort of hospitalized children. All samples were tested for the presence of viral pathogens using molecular methods. Questionnaires were sent to the parents/carers of the children recruited to the structured surveillance cohort in order to collect data that would allow an estimation of the severity of illness by means of the Vesikari score, and of the cost associated with gastrointestinal disease in this age group. A viral aetiological agent was detected in 53.5% of samples tested. Rotavirus was the most common pathogen found in all three cohorts followed by norovirus and enteric adenoviruses. Multiple viruses were found in 8% of the samples, and commonly involved rotavirus and any other virus. G1P[8] was the most commonly detected rotavirus strain and there was no significant difference in the distribution of rotavirus genotypes among the three cohorts. Analysis of the questionnaires indicated that rotavirus infections were likely to be more severe than any other virus infection, and children from whom a viral pathogen was identified were more likely to require rehydration therapy.

Head and neck pilomatrixoma in children

OBJECTIVE

To provide a review of the current information on the etiology, clinical presentation, management, and outcome of pilomatrixoma of the head and neck in children.

DESIGN

Retrospective review.

SETTING

A tertiary care pediatric center.

PATIENTS

Fifty-one pediatric patients with a diagnosis of pilomatrixoma of the head and neck.

INTERVENTION

All patients underwent excision of pilomatrixoma from January 1997 to March 1999. A total of 55 tumors were studied.

RESULTS

A preponderance of girls (n = 36; 71%) presented with this condition. The average age at diagnosis was 5.7 years, and the average size of the lesion was 1 cm. The skin of the cheek and the periorbital area were the most commonly involved sites. Only 27 lesions (49%) had a correct preoperative diagnosis. Two (4%) of 55 tumors recurred after complete surgical excision.

MAIN OUTCOME MEASURES

The age and sex of the patient, preoperative diagnosis, time elapsed before diagnosis, site and size of the tumor, length of follow-up, presence of multiple or previous pilomatrixomas, and recurrence.

CONCLUSIONS

Preoperative diagnosis may be improved with increased awareness of pilomatrixoma, a common, benign skin tumor in children. Clinical findings will aid in an accurate diagnosis. Recurrence after complete local excision is rare.

Molecular mass, stoichiometry, and assembly of 20 S particles

N-Ethylmaleimide-sensitive factor (NSF), soluble NSF attachment proteins (SNAPs), and SNAP receptor (neuronal SNARE) complexes form 20 S particles with a mass of 788 +/- 122 kDa as judged by scanning transmission electron microscopy. A single NSF hexamer and three alpha SNAP monomers reside within a 20 S particle as determined by quantitative amino acid analysis. In order to study the binding of alpha SNAP and NSF in solution, to define their binding domains, and to specify the role of oligomerization in their interaction, we fused domains of alpha SNAP and NSF to oligomerization modules derived from thrombospondin-1, a trimer, and cartilage oligomeric matrix protein, a pentamer, respectively. Binding studies with these fusion proteins reproduced the interaction of alpha SNAP and NSF N domains in the absence of the hexamerization domain of NSF (D2). Trimeric alpha SNAP (or its C-terminal half) is sufficient to recruit NSF even in the absence of SNARE complexes. Furthermore, pentameric NSF N domains are able to bind alpha SNAP in complex with SNAREs, whereas monomeric N domains do not. Our results demonstrate that the oligomerization of both NSF N domains and alpha SNAP provides a critical driving force for their interaction and the assembly of 20 S particles.

Metformin in an HIV-infected patient with protease inhibitor-induced diabetic ketoacidosis

OBJECTIVE

To describe a case of diabetes mellitus and diabetic ketoacidosis in a patient receiving protease inhibitor therapy and to describe the patient's response to treatment with metformin.

CASE SUMMARY

A 49-year-old HIV-positive white man who was receiving indinavir, stavudine, and lamivudine for more than two years presented with shortness of breath and significant weight loss over the previous month. On admission, he had a pH of 7.11 and PaCO2 of 12.9 mm Hg. Laboratory investigations revealed glucose 420 mg/dL, a total carbon dioxide 5 mEq/L, and anion gap of 32. Beta-hydroxybutyrate was 5.9 mmol/L (normal value <0.4 mmol/L). Urine was highly positive for glucose and ketones. The patient was given intravenous fluids and an insulin infusion was started. Five days later, he was discharged on 60 units of insulin per day. Following discharge, efavirenz was substituted for indinavir. Metformin was added and six months following discharge the patient's blood glucose was well controlled with 36 units of insulin per day.

DISCUSSION

New-onset diabetes mellitus has been reported in HIV-infected patients receiving protease inhibitors. To date, diabetic ketoacidosis has been an infrequent acute complication. The mechanism by which protease inhibitors cause diabetes is unclear; however, studies have noted insulin resistance and increased proinsulin. Metformin increases the sensitivity of peripheral tissues to insulin and appeared to be useful in this patient. However, further clinical research is needed.

CONCLUSIONS

Monitoring glucose concentrations in HIV-positive patients receiving protease inhibitors is important to prevent the development of acute complications, including diabetic ketoacidosis. We recommend that these patients have their fasting serum glucose concentration measured at baseline, with follow-up every three months. The role of metformin and the thiazolidinedione antidiabetic agents in the management of protease inhibitor-induced diabetes requires further study.

SPG15, a new locus for autosomal recessive complicated HSP on chromosome 14q

The authors studied two families with autosomal recessive hereditary spastic paraplegia (HSP) complicated by the presence of additional symptoms of pigmented maculopathy, distal amyotrophy, dysarthria, mental retardation, and further intellectual deterioration. Evidence was obtained for linkage to a locus on chromosome 14q that is distinct from the SPG3 locus for autosomal dominant HSP (D14S77: lod score of 4.20 at zero recombination). Haplotype construction of nearby markers confirms the existence of this novel HSP locus (SPG15) and narrows it to a 19-cM interval flanked by D14S1038 and D14S61.

Phosphorylation causes subtle changes in solvent accessibility at the interdomain interface of methylesterase CheB

The crystal structure of the unphosphorylated state of methylesterase CheB shows that the regulatory domain blocks access of substrate to the active site of the catalytic domain. Phosphorylation of CheB at Asp56 results in a catalytically active transiently phosphorylated enzyme with a lifetime of approximately two seconds. Solvent accessibility changes in this transiently phosphorylated state were probed by MALDI-TOF-detected amide hydrogen/deuterium exchange. No changes in solvent accessibility were seen in the regulatory domain upon phosphorylation of Asp56, but two regions in the catalytic domain (199-203 and 310-317) became more solvent accessible. These two regions flank the active site and contain domain-domain contact residues. Comparison with results from the isolated catalytic domain-containing C-terminal fragment of CheB (residues 147-349) showed that the increased solvent accessibility was less than would have occurred upon detachment of the regulatory domain. Thus, phosphorylation causes subtle changes in solvent accessibility at the interdomain interface of CheB.

Masses of the salivary gland region in children

BACKGROUND

Noninflammatory masses of the salivary gland region in children are extremely rare. Therefore, very few published individual and institution-based experiences exist.

DESIGN

Retrospective chart review from 1990 through 1997.

SETTING

University-based children's hospital.

DESIGN

Patients 18 years of age or younger with a tumor in the salivary gland region. Masses of infectious origin were excluded. Hemangiomas and lymphangiomas were tallied for relative incidences only.

RESULTS

Three hundred twenty-four consecutive cases of salivary gland masses were found: 192 hemangiomas (59.2%), 89 lymphangiomas (27.5%), and 43 (13.3%) solid masses. No significant difference was found between the age at presentation of the patients with benign solid tumors and the patients with malignant solid tumors (mean + SEM age, 7.2 + 0.7 years). Sixty-one percent of the masses were found in the parotid region; 18% were localized to the submandibular gland region; and the remaining 21% were located in a minor salivary gland site. The most common benign perisalivary masses were pilomatrixomas (20.9%), followed by pleomorphic adenomas (11.6%). The most common malignant masses were mucoepidermoid carcinomas (9.3%), followed by rhabdomyosarcomas (7.0%). Treatment was individualized to the disease. Twenty-two patients had adequate data for follow-up analysis (mean + SEM follow-up, 30.0 + 8.4 months). Four patients (18.2%) experienced recurrent or residual disease and were alive with disease at last follow-up, and 100% of our population demonstrated disease-specific survival at last follow-up.

CONCLUSIONS

Vascular lesions outnumber solid tumors of the salivary gland region. The most common salivary tumors were pleomorphic adenomas, followed by mucoepidermoid carcinomas. Although certain solid salivary masses may demonstrate locally aggressive behavior, the overall prognosis is favorable. Arch Otolaryngol Head Neck Surg. 2000;126:1435-1439

Sudden death from pelvic hemorrhage after bilateral central fracture dislocations of the hip due to an epileptic seizure

Fracture and dislocation of major joints may be caused by the forceful tonic muscular contractions of seizure activity. A 77-year-old man who was found dead in bed with no sign of external trauma had bilateral central fracture dislocations of the femoral head through the acetabular floor with fatal pelvic hemorrhage and extensive pulmonary fat and bone marrow embolism. He had epilepsy, but the last seizure was 6 years earlier, and he had long discontinued medication. The fractures were attributed to a new unwitnessed seizure. This is the twentieth case of central fracture dislocation of the hip since 1970, when better anesthesia eliminated convulsive therapy-induced fractures. The authors review these 20 cases. Seizures followed inflammation, infarction or neoplasia of the brain, eclampsia, metabolic or iatrogenic causes, or epilepsy (6 cases, 2 of which had no prior seizures for 5 years). There were 11 men (mean age, 64 years) and 9 women (mean age, 47 years). Fractures were unilateral in 13 and bilateral in 7. Additional fractures (in vertebrae, shoulders, or femur) were present in eight. Only eight had prior bone disease. Local symptoms led to diagnosis in most, but two were identified incidentally on imaging. The current patient was the only one to die suddenly, but six other patients presented with shock and three died (one of whom had injuries that led to a suspicion of manslaughter). Central fracture-dislocation of the hip is a rare and little known consequence of seizures, with strong potential for misdiagnosis and lethal complications.

Laryngeal histologic findings in infants with palatal defects with or without craniofacial malformations

The objective of this study was to determine whether specimens from infants with palatal defects (PDs) with or without craniofacial malformations (CFMs) exhibit aberrant laryngeal histologic findings compared with specimens from normal infants. Ten laryngeal specimens from infants with PDs with or without CFMs were histologically compared with 7 laryngeal specimens defined as normal from the same collection. Both groups were similar in terms of demographics and airway manipulation. All infants were prelingual. Comparisons were made at 3 levels: supraglottic, glottic, and subglottic. Histologically, no significant differences in primary laryngeal structures were found between the PD with or without CFM group and the group defined as normal. Acquired and intubation-type injuries, such as inflammation, ulceration, capillary congestion, and scar tissue, were more prevalent and severe in the study group. The primary laryngeal histologic findings of specimens from individuals with PDs with or without CFMs do not differ substantially from those from normal individuals; however, individuals with PDs do appear to be somewhat more susceptible to intubation injury and other acquired laryngeal injury. Meticulous airway management is essential.

Anterior submucous laryngeal cleft

Upper airway obstruction in the newborn is frequently due to congenital laryngeal anomalies. One of these, the posterior laryngeal cleft, is often associated with subglottic stenosis and respiratory difficulty. This discussion of the anterior laryngeal cleft reports findings in an infant who required intubation immediately after birth and survived only 3 days. The anterior cricoid cleft was associated with severe congenital anomalies including congenital tracheal stenosis.

Unilateral true vocal fold paralysis: cause of right-sided lesions

At the Georgetown University Center for the Voice, 778 patients were referred for evaluation between July 1, 1990, and June 30, 1995. During this 5-year period, right true vocal fold paralysis or paresis was diagnosed in 24 of these patients (3%). Videostroboscopy, voice analysis, and patient records were reviewed. Ages ranged from 23 to 80 years, and sex distribution approximated a 1:1 ratio. The patients presenting symptoms included hoarseness, dysphagia, choking, voice pitch change, voice weakness, fatigability, and breathiness. Sources of the vocal fold dysfunction included iatrogenic, traumatic, central, and infectious causes.

Postmeningitic ossification in pediatric cochlear implantation

OBJECTIVE

The goals of this study were to retrospectively review high-resolution CTs (HRCTs) of pediatric postmeningitic cochlear implant recipients and to correlate results with surgical findings.

METHODS

HRCTs of 20 children (11 months to 12 years old) who underwent implantation with multichannel devices were reviewed. Results were correlated with the degree of ossification observed at surgery.

RESULTS

Ninety percent of subjects required drilling of ossified bone within the basal turn at surgery. HRCT of the cochleas suggested ossification within the basal turn in 45% (50% sensitivity). Ossification of the lateral semicircular canal on HRCT was present in 72% (77% sensitivity). Five of 6 cases without radiographic evidence of ossification had positive findings at surgery.

CONCLUSION

Ossification is a common occurrence in postmeningitic deaf children. Ossification of the lateral semicircular canal on HRCT is a more sensitive measure for predicting ossification than evidence of cochlear involvement. Absence of ossification on HRCT is no guarantee of cochlear patency at the time of implantation.

Complications of pediatric laryngotracheal reconstruction: prevention strategies

A retrospective chart review was performed to quantify the postoperative complications and outcomes of 82 consecutive cases of laryngotracheal reconstruction (LTR) and cricotracheal resection (CTR) performed at a pediatric tertiary care hospital over the last 9 years. Six cases of respiratory syncytial virus (RSV) bronchiolitis and 8 cases of cervical pseudomonal wound abscess (PWA) were identified in a total of 12 patients. All of these infections occurred after single-stage LTR or CTR. Both RSV bronchiolitis and PWA were associated with significantly more unexpected days of intubation and admission to the intensive care unit, as well as higher rates of failure of LTR. Ossification of the cricoid cartilage, grade IV subglottic stenosis, and untreated gastroesophageal reflux disease (GERD) were also associated with restenosis. Trisomy 21 did not significantly influence the success rate of pediatric LTR. Both RSV bronchiolitis and PWA are potentially preventable complications of pediatric LTR and CTR. We propose strategies to prevent these infections. We also advocate the treatment of GERD during the healing phase of LTR.

Giant ameloblastoma: report of an extreme case and a description of its treatment

Ameloblastoma is an odontogenic tumor that usually occurs in the mandible. It is an aggressive but benign tumor of epithelial origin that is rarely metastatic. We report the case of a 53-year-old woman who had a massive ameloblastoma of the mandible. The tumor measured 15.2 x 11.4 x 12.0 cm. The patient had oral bleeding that required a transfusion. The workup included three-dimensional imaging, arteriography, and embolization to control bleeding. Surgical management entailed the resection of the entire left mandible and right symphysis, followed by reconstruction with a free fibular flap. To our knowledge, this is the largest reported ameloblastoma managed with three-dimensional imaging, radical resection, and free-flap reconstruction. This article also reviews aspects of the differential diagnosis, pathology, and management of jaw tumors.

Management of congenital subglottic hemangioma

OBJECTIVE

This study was conducted to assess the safety and efficacy of individualized management of congenital subglottic hemangioma (CSH) at the Children's Memorial Hospital in Chicago; describe treatment modalities, including endoscopic excision with the carbon dioxide (CO2) laser, systemic corticosteroids, and intralesional corticosteroid injection with short-term intubation; and determine the success of these various strategies in avoiding tracheotomy.

METHODS

During the 10-year period between January 1, 1988 and December 31, 1997, 28 infants were diagnosed with CSH. A retrospective review of medical records was undertaken to determine demographics, presenting symptoms, location of the lesion, therapeutic modality, and complications. All patients were contacted at the time of writing.

RESULTS

Twenty-eight patients met the criteria for this study. Gender distribution was 1.8:1 female to male. Age at diagnosis ranged from 4 weeks to 8 months, with a mean of 78.8 days and a median of 60 days. The location of CSH was most often posterior and on the left. Associated hemangiomas were found in 14 (50%) cases. The most common symptoms were stridor and cough. Management included 1 to 13 operative direct laryngoscopies and bronchoscopies, endoscopic excision with the (CO2) laser, and the use of systemic and intralesional corticosteroids. No patient required tracheotomy.

CONCLUSION

Morbidity and the need for tracheotomy in CSH patients can be minimized using a combination of therapeutic modalities. Each infant's treatment is individualized based on the severity of the patient's symptoms and the morphology of the lesion.

Complement resistance in Borrelia burgdorferi strain 297: outer membrane proteins prevent MAC formation at lysis susceptible sites

Two variants of Borrelia burgdorferi strain 297, complement-resistant wild-type (WT297) and complement-sensitive mutant (MUT297), were used as a model to study the mechanism of resistance to the alternative complement pathway in this organism. No difference in the quantity of membrane attack complex (MAC) deposition on WT297 and MUT297 was observed after 2 h incubation with normal human serum (NHS), at which time 4% of WT297 and 95% of MUT297 were killed. The polymerization of C9 bound to WT297 and MUT297 was demonstrated by immunoblotting using an anti-C9 polyclonal antibody. Immunofluorescence and thin-section immunoelectron microscopy showed MAC to be diffusely distributed on the outer membrane of both variants. Furthermore, MAC appeared to be tightly bound to the surface of both variants as demonstrated by elution studies. Protease treatment rendered WT297 susceptible to killing by NHS, suggesting that outer membrane proteins may be associated with complement resistance of WT297. One- and two-dimensional gel electrophoreses showed that proteins of 20 and 30 kDa, and 66 kDa were present in WT297 but were absent or sparse in trypsin-treated WT297 and MUT297. Interestingly, immunoblotting using a polyclonal antibody against C3 showed that C3 fragments appeared to bind different acceptors on WT297 than on trypsin-treated WT297, or MUT297. Therefore, the binding of C3 fragments to acceptors on WT297, in contrast to MUT297, may not direct the formation of the MAC to lysis-susceptible sites on the surface of the bacterium, resulting in the complement resistance of WT297.

Coupling of coat assembly and vesicle budding to packaging of putative cargo receptors

COPI-coated vesicle budding from lipid bilayers whose composition resembles mammalian Golgi membranes requires coatomer, ARF, GTP, and cytoplasmic tails of putative cargo receptors (p24 family proteins) or membrane cargo proteins (containing the KKXX retrieval signal) emanating from the bilayer surface. Liposome-derived COPI-coated vesicles are similar to their native counterparts with respect to diameter, buoyant density, morphology, and the requirement for an elevated temperature for budding. These results suggest that a bivalent interaction of coatomer with membrane-bound ARF[GTP] and with the cytoplasmic tails of cargo or putative cargo receptors is the molecular basis of COPI coat assembly and provide a simple mechanism to couple uptake of cargo to transport vesicle formation.

Birth trauma in the head and neck

OBJECTIVES

To review the medical records of neonates found to have birth-associated trauma of the head and neck region. To describe the anomalies, physical findings, and possible sequelae of these injuries and to bring attention to the cause of mechanical birth injury as a potential cause of anomalies in the infant.

DESIGN

Case-controlled retrospective chart review of a cohort of patients identified with birth-associated trauma to the head and neck from January 1, 1991, to March 1, 1997.

SETTING

Academic tertiary care medical center.

PATIENTS

Medical records from infants born or transferred with the diagnosis of birth trauma were reviewed. Medical records from a control group of 148 uninjured full-term infants born during the same period were reviewed for comparison. Neonatal charts, including labor and delivery records, were analyzed.

MAIN OUTCOME MEASURES

Each patient record was reviewed for diagnosis, associated injuries, maternal statistics, gestational age, birth weight and size, Apgar scores, type of delivery, length of labor, complications of labor, and length of hospital stay.

RESULTS

One hundred sixty-four infants (incidence, 0.82%; prevalence, 9.5 per 1000 live-births) were identified with 175 birth-associated injuries to the head and neck. The most common finding was cephalhematoma (56.6%). Other findings included scalp and/or facial lacerations (12%) and hematomas (2.3%), facial nerve paresis (8.6%), brachial plexus injuries (5.1%), clavicular (9.1%) and skull fracture (2.9%), nasal septal dislocation (0.6%), and phrenic (1.7%) and laryngeal nerve injuries (0.6%). Risk factors included birth weight (P = .001) , vaginal delivery (P = .001), primiparity (P = .02), forceps delivery (P = .005), vacuum delivery (P = .001), infants categorized as large for gestational age (P = .02), and male infant sex (P = .03). Apgar scores were also noted to be lower in our study population (P = .001). Risk factors for specific types of injuries varied. However, facial nerve paralysis was associated with multiple birth injuries (P = .001), and 2 of 3 phrenic nerve injuries co-occurred with brachial plexus injuries. Correlation coefficients for factors such as maternal age, gravidity, and race were low.

CONCLUSION

Birth-associated head and neck trauma is rare. However, mechanical birth-associated trauma must be considered when assessing anomalies, injuries, respiratory difficulty, or feeding difficulties in the neonate or infant. A comprehensive approach is required to diagnose and manage these patients.

Cognitive performance at school age of very low birth weight infants with bronchopulmonary dysplasia

The hypothesis was that bronchopulmonary dysplasia (BPD) adversely affects cognitive performance at school age. This prospective cohort study examined three groups of children at 8 to 10 years of age. Group 1 (n = 311) consisted of very low birth weight (VLBW) infants without BPD and Group 2 (n = 95) consisted of VLBW infants with BPD. Group 3 (n = 188) consisted of term infants without BPD. Regression analysis determined the effect of BPD on eight performance measures while controlling for possible confounding variables. Children in Group 3 had the best performance and children in Group 2 had the poorest performance on all measures. These differences were significant (p = .0001) for the Full Scale IQ, Performance IQ, and reading and math grades and ages. Children in Groups 3 and 1 performed better than children in Group 2 for the Verbal IQ (p = .0001) and the Developmental Test of Visual-Motor Integration (p = .0012), but for these two measures there was no significant difference between children in Groups 3 and 1. Thus, poorer performance was found in VLBW infants with a history of BPD.

High angiogenic activity in cells isolated from cystic hygroma: role of bFGF

BACKGROUND

Cystic hygromas are characterized by a proliferation of small vessels and lymphatics with intervening fibrous tissue. Studies have shown malignant tumors and some benign neoplasms are dependent on angiogenesis, the induction of new capillaries from preexisting vessels. Growth and progression of these tumors are associated with a disturbance in the balance of angiogenic inducers and inhibitors. We have postulated that cells derived from cystic hygromas are angiogenic due to secretion of higher levels of angiogenic inducers that promote vascular proliferation.

DESIGN

A large cystic mass was surgically removed and a portion of the sterile tumor was immediately placed in the medium. The tissue was minced, washed in phosphate-buffered saline, and grown to near confluence. Conditioned medium was collected under serum-free conditions after 48 hours. Secreted proteins were concentrated, quantitated, and analyzed in an in vitro endothelial cell migration assay and by Western blot. Antibody to factor VIII-related antigen was performed to confirm endothelial cell origin of the cultured cells.

MAIN OUTCOME MEASURES

In vitro angiogenic activity of secreted proteins in a capillary endothelial migration assay was tested by using blocking antibodies to angiogenic inducer, basic fibroblast growth factor, and angiogenic inhibitor, thrombospondin-1. Total protein levels of thrombospondin-1 were determined by Western blot.

RESULTS

Cells isolated from cystic hygroma are angiogenic in vitro and this angiogenic activity is due to secretion of high levels of angiogenic inducer, basic fibroblast growth factor, and lower levels of naturally occurring angiogenic inhibitor, thrombospondin-1.

CONCLUSIONS

Cystic hygromas may represent another neoplasm dependent on angiogenesis. The angiogenic activity is due in part to elevated levels of potent angiogenic inducer, basic fibroblast growth factor. Antiangiogenic therapy directed at the endothelial cell may help suppress the growth of cystic hygromas.

Changes in bacterial flora associated with skin damage on hands of health care personnel

In a prospective observational study of 40 nurses (20 with diagnosed hand irritation and 20 without), nurses with damaged hands did not have higher microbial counts (P = .63), but did have a greater number of colonizing species (means: 3.35 and 2.63, P = .03). Although numbers were small, nurses with damaged hands were significantly more likely to be colonized with Staphylococcus hominis (P = .03). Fifty-nine percent of S hominis isolates from nurses with damaged hands were resistant to methicillin compared with 27% of isolates from those with healthy skin (P = .14). Twenty percent of nurses with damaged hands were colonized with Staphylococcus aureus compared with none of the nurses with normal hands (P = .11). Nurses with damaged hands were also twice as likely to have gram-negative bacteria (P = .20), entercocci (P = .13), and Candida (P = .30) present on the hands. Antimicrobial resistance of the coagulase-negative staphylococcal flora (with the exception of S hominis) did not differ between the 2 groups, nor did a trend toward increasing resistance exist when compared with other studies during the past decade. Skin moisturizers and protectant products were used almost universally by nurses at work, primarily products brought from home. Efforts to improve hand condition are warranted because skin damage can change microbial flora. Such efforts should include assessment or monitoring of hand care practices, formal institutional policy adoption and control of use of skin protectant products or lotions, and prudent use of latex gloves or more widespread use of powder-free and nonlatex products.

The value of the Infant/Child Monitoring Questionnaire for identification of developmental disability among neonatal intensive care unit graduates

OBJECTIVE

We hypothesized that the Infant/Child Monitoring Questionnaire (ICMQ) could be used to identify at-risk infants eligible for developmental interventional services.

STUDY DESIGN

Of this cross-sectional observational study, group A (n = 108) included a retrospective review of moderate risk infants scheduled for developmental assessment clinic (DAC) visits. Group B (n = 108) included moderate-risk infants whose parents completed the ICMQ. Group C (n = 67) included high-risk infants who were seen in the DAC and whose parents completed the ICMQ.

RESULTS

For group A infants, 43.5% were seen in the DAC; 10.6% of these visits resulted in an intervention. For group B infants, 56.5% of parents completed the ICMQ; 66.7% of subsequent visits resulted in an intervention. For group C infants, comparison of ICMQ and DAC visits showed moderate agreement (kappa = 0.50).

CONCLUSION

The ICMQ is a useful tool to identify moderate-risk infants requiring further intervention, but caution must be used when applied to high-risk infants.

Patients' attitudes about autonomy and confidentiality in genetic testing for breast-ovarian cancer susceptibility

The identification of BRCA1 and BRCA2, two breast-ovarian cancer susceptibility genes, has brought many ethical and social issues to the forefront. This paper presents the results of a survey assessing the attitudes of 238 unaffected first-degree relatives of women with breast or ovarian cancer regarding the ethical issues of autonomy and confidentiality as they relate to BRCA1/2 testing. Baseline knowledge about BRCA1/2 and ethnic and psychosocial characteristics of our study population were examined to determine their association with women's attitudes. The majority of women (86-87%) felt that health care providers should not disclose the results of genetic tests for breast-ovarian cancer susceptibility to insurance companies or employers without written consent; however, only 56-57% felt that written consent should be required for a spouse or immediate family to receive this information. Ninety-eight percent of the women surveyed agreed that genetic testing for breast-ovarian cancer risk should be voluntary. Likewise, most women (95%) agreed that a person should be able to have genetic testing against a doctor's recommendation and 88% of the women surveyed agreed that parents should be able to consent to genetic susceptibility testing on behalf of their minor children. African American women were less concerned than Caucasian women about the protection of confidentiality in families, they were more likely to agree that an individual should still have access to testing when their physicians recommended against it, and they were more supportive of parents' rights to consent to genetic predisposition testing on behalf of their minor children. Women with coping styles characterized by higher optimism were more likely to favor access to genetic testing when a physician recommended against it, and to support parents' rights to consent to testing of their minor children. Therefore, the setting and manner in which genetic counseling and testing are delivered must be appropriately tailored to reflect these attitudinal differences and preferences.

Interleukin-6 is expressed at high levels in the CNS in Lyme neuroborreliosis

In patients with Lyme neuroborreliosis, inflammation and symptoms of fatigue and malaise occur out of proportion to the relatively low number of spirochetes present. Previous studies have identified interleukin-6 (IL-6) as a candidate molecule for amplification of CNS inflammation in this disease. We pursued this possibility by measuring cytokine gene expression by reverse-transcriptase polymerase chain reaction (RT-PCR) in the brain of rhesus macaques actively infected with Borrelia burgdorferi. Samples of brain tissue were screened for IL-6 and interferon gamma using RT-PCR-ELISA, a technique that uses RT-PCR, subsequent hybridization of the PCR product with a biotinylated probe, and capture and ELISA readout of hybridization product. The number of copies in positive samples was then quantitated using qRT-PCR-ELISA, in which wild-type cytokine cDNA competes with recombinant competitor DNA in the PCR. Elevated levels of IL-6 cDNA and, to a lesser extent, interferon gamma were detected in three of three nonhuman primates with persistent infection with B burgdorferi, whereas the brains of three uninfected animals and undetectable levels of gene expression of these cytokines. These data support the hypothesis that cytokines such as IL-6 are important amplification molecules for CNS inflammation in Lyme neuroborreliosis.

Benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) has received renewed clinical interest. At the Johns Hopkins Otological Vestibular Laboratory, 781 patients were tested on more than one occasion between September 1976 and November 1992. Of these patients, 187 (24%) were found to have positional nystagmus consistent with a diagnosis of BPPV. A retrospective analysis of these patients' records, including vestibular test and eye movement reports, audiograms, questionnaires, and hospital charts was performed. After this review, the nystagmus, initially diagnosed as due to BPPV, was believed to be a manifestation of another disease process in 36 cases. Of the remaining 151 cases, 52 (34%) presented with no significant preceding disorder and have been termed primary BPPV. In the remaining 99 patients we found coexisting or associated disorders which included Meniere's disease, head trauma, prior ear surgery, vestibular neuronitis, migraine, and others. Forty-five of these 151 patients (31%) had an associated diagnosis of Meniere's disease. To our knowledge a significant association between Meniere's disease and BPPV has not been reported. A review of the literature with discussion of BPPV and the associated disorders is offered.

Molecular cloning and expression of two cDNAs encoding asparagine synthetase in soybean

Two cDNA clones (SAS1 and SAS2) encoding different isoforms of asparagine synthetase (AS; EC 6.3.5.4) were isolated. Their DNA sequences were determined and compared. The amino-terminal residues of the predicted SAS1 and SAS2 proteins were identical to those of the glutamine binding domain of AS from pea, asparagus, Arabidopsis and human, suggesting that SAS1 and SAS2 cDNAs encode the glutamine-dependent form of AS. The open reading frames of SAS1 and SAS2 encode a protein of 579 and 581 amino acids with predicted molecular weights of 65182 and 65608 Da respectively. Similarity of the deduced amino acid sequences of SAS1 and SAS2 with other known AS sequences were 92% and 93% for pea AS1; 91% and 96% for pea AS2; 88% and 91% for asparagus; 88% and 90.5% for Arabidopsis; 70.5% and 72.5% for E. coli asnB and 61% and 63% for man. A plasmid, pSAS2E, was constructed to express the soybean AS protein in Escherichia coli. Complementation experiments revealed that the soybean AS protein was functional in E. coli. Southern blot analysis indicated that the soybean AS is part of a small gene family. AS transcript was expressed in all tissues examined, but higher levels were seen in stem and root of light-grown tissue and leaves of dark-treated tissue.

Adducin regulation. Definition of the calmodulin-binding domain and sites of phosphorylation by protein kinases A and C

Adducin promotes association of spectrin with actin and caps the fast growing end of actin filaments. Adducin contains N-terminal core, neck, and C-terminal tail domains, is a substrate for protein kinases A (PKA) and C (PKC), and binds to Ca2+/calmodulin. Ser-726 and Ser-713 in the C-terminal MARCKS-related domains of alpha- and beta-adducin, respectively, were identified as the major phosphorylation sites common for PKA and PKC. PKA, in addition, phosphorylated alpha-adducin at Ser-408, -436, and -481 in the neck domain. Phosphorylation by PKA, but not PKC, reduced the affinity of adducin for spectrin-F-actin complexes as well as the activity of adducin in promoting binding of spectrin to F-actin. The myristoylated alanine-rich protein kinase C substrate-related domain of beta-adducin was identified as the dominant Ca2+-dependent calmodulin-binding site. Calmodulin-binding was inhibited by phosphorylation of beta-adducin and of a MARCKS-related domain peptide by PKA and PKC. Calmodulin in turn inhibited the rate, but not the extent, of phosphorylation of beta-adducin, but not alpha-adducin, by PKA and that of each subunit by PKC. These findings suggest a complex reciprocal relationship between regulation of adducin function by calmodulin binding and phosphorylation by PKA and PKC.

Pediatric neurotologic skull base surgery

The objectives of neurotologic skull base surgery are complete resection of the lesion and high-grade function following surgery. There is a perception that these goals are more difficult to achieve in children than in adults. Skull base disease in children and adolescents is rare. Of the 292 skull base tumors treated from 1970 to 1995 by The Otology Group in Nashville, 15 were in patients 21 years of age or younger, with only 5 patients under 10 years old. In this retrospective study, the authors review these 15 cases and compare them to their adult series. The pathology encountered in the 15 young patients with skull base tumors included 8 glomus lesions and 4 schwannomas. In these patients, 13 tumors occurred sporadically, and 2 tumors were related to neurofibromatosis type 2. Advanced-stage disease and malignancy were prevalent in this younger patient group. All patients underwent excision of their skull base tumor, with one procedure considered a subtotal resection. As compared with an adult glomus tumor series, postoperative cranial nerve function and complication rates were generally worse in the young glomus patients. However, postoperative function and complications were consistent with the extensive procedures required for the treatment of advanced disease. Despite the advances that have been made in imaging and treatment modalities, this study illustrates the need for more timely diagnosis in younger patients with skull base tumors.

Molecular and evolutionary analyses of a variable series of genes in Borrelia burgdorferi that are related to ospE and ospF, constitute a gene family, and share a common upstream homology box

In this study we report on the molecular characterization of a series of genes that constitute a gene family related to ospE and ospF. Some members of this family appear to represent recombined or variant forms of ospE and ospF. Variant ospE and ospF genes were found in several Borrelia burgdorferi isolates, demonstrating that their occurrence is not a phenomenon relevant to only a single isolate. Hybridization analyses revealed that the upstream sequence originally identified 5' of the full-length ospEF operon exists in multiple copies ranging in number from two to six depending on the isolate. This repeated sequence, which we refer to as the upstream homology box (UHB), carries a putative promoter element. In some isolates, UHB elements were found to flank copies of ospE and ospF that exist independently of each other. We refer to this group of UHB-flanked genes collectively as the UHB gene family. The evolutionary relationships among UHB gene family members were assessed through DNA sequence analysis and gene tree construction. These analyses suggest that some UHB-flanked genes might actually represent divergent forms of other previously described genes. Analysis of the restriction fragment length polymorphism patterns of the UHB-flanked genes among B. burgdorferi isolates demonstrated that these patterns are highly variable among isolates, suggesting that these genes are not phylogenetically conserved. The variable restriction fragment length polymorphism patterns could indicate recombinational activity in these sequences. The presence of numerous copies of the UHB elements and the high degree of homology among UHB-flanked genes could provide the necessary elements to allow for homologous recombination, leading to the generation of recombination variants of UHB gene family members.

Resistance to tick-borne spirochete challenge induced by Borrelia burgdorferi strains that differ in expression of outer surface proteins

Hamsters were immunized with thimerosal-killed Borrelia burgdorferi 297 or a mutant of 297 (M297) that lacks the 49-kb linear plasmid and expression of outer surface proteins A and B (OspA and OspB). Ixodes scapularis nymphs infected with either the B. burgdorferi sensu stricto strain 297 or JMNT, similar in OspA and OspB but differing in OspC expression, were used to evaluate protection. In a homologous challenge, 24 hamsters were vaccinated, 8 each with 297 or M297 and 8 sham (adjuvant)-vaccinated controls. Hamsters vaccinated with either bacterin were completely protected against a natural tick bite or subcutaneous (s.c.) inoculation of 297. Borreliae were effectively eliminated from 80 to 90% of the 297-infected ticks that fed on four hamsters immunized with the 297 bacterin. Cultures of spirochetes isolated from the ticks that remained infected were infectious and induced joint inflammation in naive hamsters. There was no reduction of strain 297 spirochetes in ticks that fed on four hamsters immunized with M297, but the hamsters were protected. Results with the M297 bacterin indicate that proteins other than OspA or OspB can protect hamsters against a tick challenge without eliminating B. burgdorferi in the tick. In a heterologous challenge, 36 hamsters were vaccinated, 12 with each bacterin and 12 controls. None of the hamsters immunized with either bacterin were protected from a challenge involving JMNT-infected ticks, while two of four were protected against an s.c. challenge. Hamsters challenged s.c. with strain 297 spirochetes were protected. There was partial elimination of JMNT spirochetes in ticks that fed on the group of four hamsters immunized with the 297 bacterin, and infection rates were reduced by 50 to 60%. JMNT spirochetes reisolated from the ticks that fed on 297-vaccinated hamsters also remained infectious for hamsters. In the JMNT-infected ticks that fed on four M297-immunized hamsters, there was no decline in the proportion of infected ticks. Destruction of spirochetes in ticks that fed on the hamsters vaccinated with the 297 bacterin suggests that antibodies to OspA and OspB may have been responsible, since the mutant did not induce this activity.

Pediatric tracheobronchial foreign bodies: historical review from the Johns Hopkins Hospital

We investigated changing trends in pediatric tracheobronchial foreign body removal and resident experience from 1939 to 1991. We retrieved the records of 234 cases of tracheobronchial foreign body removal at Johns Hopkins. The mean number of cases per year was 5.9. The most common foreign bodies removed were peanuts, accounting for 38.9%. The average yearly incidence of pediatric tracheobronchial foreign bodies remained relatively constant during the period studied. Our data suggested little change in outcome or complications with the advent of optical telescopes in the mid-1970s, despite their great value in improved visualization. Resident experience and training were evaluated by the number of cases attended by each resident during his or her training. The number varied from 1 to 8 cases, not including experience acquired at our sister institutions. Although complete data could not be obtained in many of the older medical records, our review suggests that despite the advantage offered by the optical forceps technology, proper training and experience in traditional rigid endoscopic techniques is still crucial to optimize outcome and minimize the risk of complications in pediatric tracheobronchial foreign body removal. Chevalier Jackson's recommendation that residency training include an animal laboratory course in foreign body removal still applies.