Induction effects of ritonavir: implications for drug interactions

OBJECTIVE

To review the literature on the induction effects of ritonavir on the cytochrome P450 enzyme system and glucuronyl transferase and identify resultant established and potential drug interactions.

DATA SOURCES

Primary literature was identified from MEDLINE (1950-April 2008), EMBASE (1988-April 2008) and International Pharmaceutical Abstracts (1970-April 2008) using the search terms ritonavir, cytochrome P450 enzyme system, enzyme induction, glucuronyl transferase, and drug interactions. Additionally, relevant conference abstracts and references of relevant articles were reviewed.

STUDY SELECTION AND DATA ABSTRACTION

All English-language articles and abstracts identified were reviewed.

DATA SYNTHESIS

Ritonavir is a well-known inhibitor of the metabolism of numerous medications that are substrates of the CYP3A and CYP2D6 pathways. It also exhibits a biphasic, time-dependent effect on P-glycoprotein of inhibition followed by induction. Numerous pharmacokinetic studies suggested that ritonavir induces cytochrome P450 enzymes 3A, 1A2, 2B6, 2C9, and 2C19, as well as glucuronyl transferase. Additionally, several case reports described clinically significant subtherapeutic effects of drugs metabolized by these isoenzymes when coadministered with ritonavir. Both therapeutic and boosting doses of ritonavir appear to induce these enzymes; however, most of the studies of low-dose ritonavir involved a second protease inhibitor such as lopinavir, darunavir, or tipranavir. It is, therefore, difficult to distinguish the relative effects of additional medications unless well-designed, 3-way studies are conducted.

CONCLUSIONS

At both therapeutic and boosting doses, ritonavir exhibits a clinically relevant induction effect on numerous drug-metabolizing enzymes. A decrease or loss of therapeutic effect may be observed when ritonavir is coadministered with medications that are substrates for these enzymes. It is important for clinicians to be aware of drugs potentially impacted by ritonavir therapy to identify and manage these interactions.

Complexity of interactions between voriconazole and antiretroviral agents

OBJECTIVE

To evaluate and summarize pertinent aspects of the literature on interactions between voriconazole and antiretroviral agents.

DATA SOURCES

Primary literature was identified through MEDLINE (1950-February 2008), EMBASE (1988-February 2008), and International Pharmaceutical Abstracts (1970-February 2008) using the search terms voriconazole, ritonavir, protease inhibitors, nonnucleoside reverse transcriptase inhibitors, raltegravir, maraviroc, and drug interactions. Additionally, relevant abstracts from infectious diseases and HIV conferences (2004-February 2008), reference citations from relevant publications, and product information monographs were reviewed.

STUDY SELECTION AND DATA ABSTRACTION

All articles identified from the data sources and published in English were reviewed. Of these, studies and reports addressing voriconazole pharmacokinetics or interactions with antiretroviral agents were evaluated.

DATA SYNTHESIS

The interactions between voriconazole and antiretroviral drugs are complex. Voriconazole and ritonavir exhibit a time- and dose-dependent interaction. Ritonavir initially inhibits voriconazole metabolism, but, with chronic administration, subsequently induces voriconazole metabolism. This interaction is more pronounced with high doses of ritonavir. Coadministration of voriconazole and efavirenz at usual doses is contraindicated because of a 2-way interaction resulting in efavirenz toxicity and decreased therapeutic effect of voriconazole. Dosage adjustments of both drugs are required. Based on pharmacokinetic characteristics, interactions between voriconazole and other protease inhibitors, nonnucleoside reverse transcriptase inhibitors (including etravirine), and maraviroc are likely but have not been well characterized in the literature. Interactions between voriconazole and nucleoside reverse transcriptase inhibitors or raltegravir are not anticipated.

CONCLUSIONS

Interactions between voriconazole and antiretrovirals have the potential for serious consequences. However, because there is limited information available, further studies are warranted to establish these interactions and clarify their appropriate management. Until then, clinicians should be aware of the potential for interactions between voriconazole and antiretroviral agents and how to monitor for these interactions in clinical practice.

Abacavir hypersensitivity reaction: an update

OBJECTIVE

To review the clinical features, risk factors, diagnosis, and management of abacavir hypersensitivity reaction (HSR).

DATA SOURCES

A MEDLINE (1950-October 2007) and EMBASE (1980-October 2007) search using key words abacavir, HIV, human immunodeficiency virus, hypersensitivity reaction, HLA-B(*)5701, and patch tests was conducted. Conference abstracts and article bibliographies were reviewed to identify relevant studies.

STUDY SELECTION AND DATA EXTRACTION

Studies that investigated the clinical and immunogenetic risk factors for abacavir hypersensitivity and the benefit of genetic screening, as well as articles that focused on the clinical presentation, assessment, and management of abacavir HSR, were considered for this review.

DATA SYNTHESIS

Abacavir hypersensitivity is an immune-mediated reaction that typically occurs within the first 6 weeks of therapy. Signs and symptoms of abacavir HSR are nonspecific, which makes the diagnosis challenging, particularly in medically complex patients. Patch testing may improve the diagnosis and confirmation of abacavir HSR, but it remains experimental. Clinical management is aimed at supportive therapy and discontinuation of abacavir. Rechallenge with abacavir is contraindicated due to the risk of precipitating a life-threatening reaction. Appropriate patient education and a clear communication plan are essential for the safe use of this medication. Identification of patients at risk of developing abacavir hypersensitivity through routine genetic screening for human leukocyte antigen (HLA) HLA-B(*)5701 represents a significant advance in the field of pharmacogenomics, with an apparent 100% negative predictive value when used to screen for abacavir HSR. Preliminary data suggest that pharmacogenetic testing for HLA-B(*)5701 is cost effective. However, until routine testing is available, pharmacovigilance is necessary for the safe and effective use of abacavir.

CONCLUSIONS

Serious adverse events associated with the use of abacavir can be avoided by appropriate recognition and management of the HSR. Screening patients for HLA-B(*)5701 prior to initiation of abacavir represents a tool to further decrease the risk of HSRs as well as unnecessary discontinuation of this drug.

Development of a telephone-based intervention for support persons to help smokers quit

This study represents the first step toward systematic behavioral treatment development and pilot testing of a novel approach to smoking cessation that utilizes adults interested in helping someone to stop smoking (i.e., support persons) as the agent of change. The counselor manual for a telephone-based intervention for support persons was developed based on a previous clinic-based intervention. Social cognitive theory served as the conceptual basis for the intervention. Ten adult non-smoking females completed the treatment protocol, consisting of six 20 - 30-min sessions and written materials. The support person was the sole recipient of the professional intervention. Feedback was obtained from 8 of the 10 participants and all 4 telephone counselors 1 week post-treatment (week 10). Results indicate that the telephone-based intervention was feasible and acceptable to participants. The intervention was refined based on participant and counselor feedback and will be subsequently tested in a randomized pilot trial.

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.

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.

Interaction between lopinavir/ritonavir and warfarin

Drug interactions involving protease inhibitors are common. Protease inhibitors are well known inhibitors of the 3A4 isozyme of cytochrome P450. Select protease inhibitors, including co-formulated lopinavir/ritonavir, may induce glucuronidation or the activity of other CYP450 isozymes. We describe the case of a patient taking warfarin who experienced a significantly decreased international normalized ratio after the initiation of antiretroviral therapy that included lopinavir/ritonavir. We review the possible mechanisms of this interaction and the reported interactions between warfarin and other protease inhibitors.

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.

Treatment of hepatitis C in HIV-coinfected patients

OBJECTIVE

To review the current management of hepatitis C virus (HCV) in persons coinfected with HIV.

DATA SOURCES

A MEDLINE search (1966-February 2006) was conducted, using key words such as HIV, human immunodeficiency virus, hepatitis C, interferon, pegylated interferon, and therapy. Article bibliographies and conference abstracts were also reviewed to identify relevant studies.

STUDY SELECTION AND DATA EXTRACTION

Studies that examined HCV treatment in individuals coinfected with HIV and articles that focused on HCV/HIV coinfection were considered for this review.

DATA SYNTHESIS

Coinfection with HIV leads to a more rapid and severe course of HCV-related liver disease. Treatment of HCV with pegylated interferon (PEG-IFN) and ribavirin therapy is relatively well tolerated in individuals coinfected with HIV, with overall sustained virologic response (SVR) rates of 27-40%. High relapse rates and poor response in HCV-genotype 1 contribute to the lower SVR in coinfected individuals compared with HCV monoinfection. Treatment of HCV is more complicated in HIV-infected persons due to increased risk of myelosuppression, drug interactions, hepatotoxicity of antiretroviral therapy, and the relative contraindication to interferon therapy in advanced HIV disease. Current guidelines recommend that all HIV-positive patients with chronic HCV infection be considered as treatment candidates for anti-HCV therapy due to the higher risk of liver disease progression. Further studies are needed, however, to define the appropriate dose and duration of therapy in HCV/HIV-coinfected individuals.

CONCLUSIONS

Response to treatment with PEG-IFN and ribavirin is poorer in patients coinfected with HCV/HIV than in those infected with HCV alone. The benefits of anti-HCV therapy, including viral eradication, need to be weighed against the risks of adverse effects and drug-drug interactions between anti-HCV and antiretroviral medications.

Chronic hepatitis C virus management: 2000-2005 update

OBJECTIVE

To review recent advances that have significantly changed the management of chronic hepatitis C virus (HCV) infection.

DATA SOURCES

A MEDLINE search (2000-July 2005) was conducted using key words such as hepatitis C, interferon, pegylated interferon, and therapy.

STUDY SELECTION AND DATA EXTRACTION

All articles pertaining to treatment of chronic HCV infection were identified. Studies evaluating HCV treatment in treatment-naive patients were considered for this review.

DATA SYNTHESIS

Over the past several years, response to treatment for chronic HCV infection has significantly improved with the use of pegylated interferon and ribavirin therapy. Treatment response is influenced by HCV genotype and viral load, as well as patient-related factors, including adherence.

CONCLUSIONS

Treatment of chronic HCV infection has improved, with overall response rates of approximately 55%. Identification and management of common adverse effects is important in maximizing adherence and response to therapy. Studies are needed to further delineate the optimum treatment of chronic HCV infection in specific patient populations.

Balance disorder and increased risk of falls in osteoporosis and kyphosis: significance of kyphotic posture and muscle strength

This controlled trial was designed to investigate the influence of osteoporosis-related kyphosis (O-K) on falls. Twelve community-dwelling women with O-K (Cobb angle, 50-65 degrees measured from spine radiographs) and 13 healthy women serving as controls were enrolled. Mean age of the O-K group was 76 years (+/-5.1), height 158 cm (+/-5), and weight 61 kg (+/-7.9), and mean age of the control group was 71 years (+/-4.6), height 161 cm (+/-3.8), and weight 66 kg (+/-11.7). Quantitative isometric strength data were collected. Gait was monitored during unobstructed level walking and during stepping over an obstacle of four different heights randomly assigned (2.5%, 5%, 10%, and 15% of the subject's height). Balance was objectively assessed with computerized dynamic posturography consisting of the sensory organization test. Back extensor strength, grip strength, and all lower extremity muscle groups were significantly weaker in the O-K group than the control group (P <0.05), except right ankle plantar flexors (P =0.09). There was a significant difference in the anteroposterior and mediolateral displacements and velocities. The O-K subjects had less anteroposterior displacement, greater mediolateral displacement, reduced anteroposterior velocity, and increased mediolateral velocity compared with controls for all conditions of unobstructed and obstructed level walking. Obstacle height had a significant effect on all center-of-mass variables. The O-K subjects had significantly greater balance abnormalities on computerized dynamic posturography than the control group (P =0.002). Data show that thoracic hyperkyphosis on a background of reduced muscle strength plays an important role in increasing body sway, gait unsteadiness, and risk of falls in osteoporosis.

Risk factors for new-onset diabetes mellitus in patients receiving protease inhibitor therapy

BACKGROUND

Metabolic complications including diabetes mellitus (DM) have been associated with protease inhibitor (PI) therapy. Risk factors for the development of DM are not well-defined.

OBJECTIVES

To determine risk factors for the development of new-onset DM in patients initiated on PI therapy.

METHODS

A retrospective cohort study was conducted to identify predictors of developing DM in subjects started on PI therapy between January 1997 and January 2003. Diabetes cases were defined as physician documentation of DM in the outpatient medical chart and/or those subjects receiving an antidiabetic agent. Logistic regression was used to examine the relationship between new-onset DM and demographic characteristics, and between new-onset DM and total treatment days with PI therapy. Body mass index could not be entered into the model due to missing height measurements.

RESULTS

A total of 496 subjects on PI therapy were included, of which 18 (3.6%) developed DM. The mean age of the subjects was 43.4+/-9.4 years (range 19 to 77) and the mean duration of therapy was 3.0+/-1.9 years (range 0.17 to 7.9). In the multivariate model, older subjects were more likely to develop DM (OR 1.12, 95% CI 1.05 to 1.19; P=0.001). This corresponds to a 12% increased risk of DM for each one-year increase in age. Subjects that weighed more had an increased risk (OR 1.06, 95% CI 1.03 to 1.10; P=0.001), as did those belonging to a non-Aboriginal minority group when compared with Caucasians (OR 6.67, 95% CI 1.56 to 28.41; P=0.01). A longer duration of PI therapy was also significantly associated with developing DM (OR 1.52, 95% CI 1.07 to 2.17; P=0.02).

CONCLUSION

A longer duration of PI therapy is associated with an increased risk of developing DM. As with HIV-negative subjects, demographic characteristics such as age, weight and ethnicity were important predictors of developing DM in the present study.

Significant reduction in risk of falls and back pain in osteoporotic-kyphotic women through a Spinal Proprioceptive Extension Exercise Dynamic (SPEED) program

OBJECTIVE

To determine the outcome of intervention with a spinal weighted kypho-orthosis (WKO) and a spinal proprioceptive extension exercise dynamic (SPEED) program on the risk of falls in ambulatory community-dwelling persons older than 60 years with osteoporosis-kyphosis at risk for falls.

SUBJECTS AND METHODS

The study had 3 stages. At stage 1 (baseline), the 12 women in the kyphotic group were compared with 13 healthy controls to assess the risk of falls and balance disorder in the kyphotic group. At stage 2, the 12 kyphotic women began the SPEED program with a WKO (2 supervised sessions in an outpatient clinic and a 4-week, daily home-based training program). At stage 3, baseline and follow-up data of the kyphotic group were compared to determine the effect of intervention.

RESULTS

At baseline, there were significant differences between the osteoporotic-kyphotic group and the control group in balance (P=.002), gait (P<.05), and strength (P<.05). After a 4-week intervention, comparison of the kyphotic group's baseline and follow-up results showed a significant change in balance (P=.003) and several gait parameters (P<.05). Mean back extensor strength improved significantly from baseline (144.0-46.5 N) to follow-up (198.6+/-55.2 N; P<.001). Lower extremity muscle strength was not changed significantly, except for improved left ankle plantar flexors (P=.02). Back pain decreased significantly (P=.001).

CONCLUSION

Balance, gait, and risk of falls improved significantly with the 4-week SPEED program.

Evaluation of HIV drug interaction web sites

BACKGROUND

Clinicians frequently consult HIV drug interaction Web sites of unknown quality.

OBJECTIVE

To systematically review and identify HIV drug interaction Web sites of high quality and usefulness for healthcare professionals.

METHODS

Relevant Web sites were identified through a structured search on commonly used search engines. An assessment tool containing 4 domains (content, reliability, access restrictions, ease of navigation) was developed. English and French Web sites were selected for review if they included HIV drug interaction information directed to healthcare professionals. Web sites were excluded if antiretroviral interaction data were not available or were out of date. Commercial online databases and sites that required payment were not included. Seventeen HIV pharmacists from across Canada participated in the review. The Web sites were ranked with total mean scores. Mean scores for each domain were then analyzed. Interrater agreement and ANOVA using the rater as a covariate were determined.

RESULTS

Nine Web sites met the criteria for review. Web sites from Toronto General Hospital (Canada), HIVinSite (beta version) (US), and the University of Liverpool (UK) ranked highest for total mean scores and for content. Other Web sites were found to be reliable, accessible, and easy to navigate; however, they did not consistently include unpublished data or data on herbal preparations, recreational drugs, or multiple interactions.

CONCLUSIONS

Three HIV interaction Web sites of high quality were identified that can be valuable tools for HIV and non-HIV health-care professionals. Regular reviews are necessary in order to keep pace with the growing body of HIV interaction data and the constant evolution of Web sites.

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.