Anesthesia and pain management for pediatric patients with dystrophic epidermolysis bullosa

STUDY OBJECTIVE

To review anesthesia and pain management in pediatric patients with recessive dystrophic epidermolysis bullosa (RDEB).

STUDY DESIGN

Retrospective study.

SETTING

University-affiliated pediatric hospital.

PATIENTS

25 pediatric patients with RDEB had a total of 121 surgical procedures.

MEASUREMENTS AND MAIN RESULTS

Pediatric patients with RDEB could have vesicles and bullae formation in the skin in response to trauma, friction, or pressure. The common surgical procedures for patients with RDEB were balloon dilation of esophageal strictures (38%), pseudosyndactyly release with or without skin graft (27%), postsurgical or skin care related dressing changes (21%), percutaneous endoscopic gastrostomy tube placement (8%), and circumcision (2%). Our anesthetic techniques included general inhalational anesthesia using mask (21%), general anesthesia using endotracheal tube (48%), and intravenous sedation (31%). No death or other major perioperative anesthetic complications occurred in these reported cases.

CONCLUSIONS

Patients with RDEB can present considerable management issues for the anesthesiologists. Anesthesia and pain management can be carefully delivered with proper preoperative evaluation and preparation for pediatric patients with RDEB.

Arsenic trioxide reduces the invasive and metastatic properties of nasopharyngeal carcinoma cells in vitro

Nasopharyngeal carcinoma (NPC) is notorious for the metastases, which are in close association with Epstein-Barr virus-encoded latent membrane protein 1 (LMP1). Arsenic trioxide (As2O3) has been shown to induce apoptosis and differentiation in NPC xenografts. Then, can it repress the cancer cells' metastasis potential? To elucidate this issue, the present study was performed. LMP1-negative cell line HNE1 and LMP1-positive cell line HNE1-LMP1 were used as in vitro model. Cells (1 x 10(5)/mL) were cultured with or without 3 microM As2O3 for 48 h. Then the survival cells were collected to investigate their potential of colony formation, attachment, invasion, and migration. Both confocal immunofluorescence staining and Western blot were used to detect the changes of LMP1 expression. The changes of MMP-9 were examined by RT-PCR assay and Western blot. The results were as follow: i) the colony formation inhibition rate (75.41 +/- 3.9% in HNE1-LMP1 cells vs 37.89 +/- 4.9% in HNE1 cells), the rate of attachment (HNE1-LMP1 vs HNE1: 56.40 +/- 3.5 vs 65.87 +/- 5.9%), the invasion inhibitory rate (HNE1-LMP1 vs HNE1: 56.50 +/- 3.7 and 27.91 +/- 2.1%), and the migration inhibitory rate (HNE1-LMP1 vs HNE1: 48.70 +/- 3.9 vs 29.19 +/- 6.27%) were all significantly different between the two cell lines (P < 0.01). ii) LMP1 was down-regulated in As2O3-treated HNE1-LMP1 cells. iii) The reduction of MMP-9 was found in As2O3-treated groups, more evident in HNE1-LMP1 cells. Thus, we conclude that As2O3 can reduce metastasis potential of NPC cells, involving inhibition of MMP-9 expression. LMP1 were also reduced in this process and seemed to enhance anti-metastasis activity of As2O3.

Combined use of androgen and sildenafil for hypogonadal patients unresponsive to sildenafil alone

To investigate the therapeutic effect of androgen on hypogonadal patients unresponsive to sildenafil alone. In total, 32 hypogonadal patients with erectile dysfunction (ED), initially had an inadequate response to sildenafil (100 mg). Oral testosterone undecanoate (Restandol, 80 mg, bid or tid) alone was supplied for 2 months, and if patients could not achieve a satisfactory erection, combined use of testosterone and sildenafil was continued thereafter. Total testosterone (TT), free testosterone (FT), and the parameters of the International Index of Erectile Function (IIEF), International Prostate Symptom Score (IPSS), and uroflow rate (UFR) were assessed. Eleven patients (34.3%) achieved satisfactory erectile function after testosterone replacement only. Another 12 (37.5%) patients experienced satisfactory intercourse after combined therapy. Serum TT and FT levels significantly increased after the use of testosterone alone (415+/-163 vs 220+/-101 ng/dl, P<0.01; 10.4+/-4.6 vs 5.1+/-1.9 ng/dl; P<0.01, respectively) and the combined use of testosterone and sildenafil (498+/-178 vs 220+/-101 ng/dl, P<0.01; 11.7+/-4.6 vs 5.1+/-1.9 ng/dl, P<0.001, respectively); as did the IIEF score (14.8+/-6.8 vs 12.6+/-7.5, P<0.01, 17.5+/-5.2 vs 12.6+/-7.5, P<0.001, respectively). However, no statistical differences were demonstrated for IPSS or UFR. In conclusions, one-third of hypogonadal patients with ED who failed to respond to sildenafil, responded to testosterone alone, another third responded to sildenafil again after normalization of testosterone. So, in hypogonadal patients with ED, androgen supplementation is first-line therapy. If patients are unresponsive to androgen alone or sildenafil alone, combined use may improve erectile function and enhance the therapeutic effect of PDE-5 inhibitors.

Membrane bioreactor application in wastewater re-use from the effluent of Bali primary WWTP, northern Taiwan

Two MBR pilot systems were constructed and tested in the Bali Primary WWTP. The pilot study shows that two MBR systems, i.e. the Green-MenBio system (MBR-1) and the Bio-MF system (MBR-2), can both fulfill the requirement of wastewater reclamation standard. The MBR-2 system is more economical compared with MBR-1 system. The cost of US dollars 0.10-0.16/m3 is estimated to reclaim the effluent of primary WWTP in Taiwan. The Bali Primary WWTP has the capacity of 1,320,000 cmd which is the biggest in Taiwan. The domestic wastewater of partial Taipei City and Taipei County are collected and transported to the Bali Primary WWTP. The effluent of the Bali Primary WWTP is then discharged into the ocean through two 3.8 m marine outfalls. The AO processes are installed in both MBR systems. More than 90% of the NH3-N can be removed through the AO and membrane processes. The outflow of the MBR systems (without RO) can reach the quality of COD <30 mg/l, BOD <10 mg/l, SS <5 mg/l, NH3-N <3 mg/L. The outflow of the MBR system is proposed to transport 40 km south to the Taoyuan County where four new industrial parks are to be constructed. Part of the reclaimed water is to be used on irrigation and another portion is to be sent to the industries after RO treatment.

Acupuncture for Persistent Hiccups in a Heart and Lung Transplant Recipient

Hiccup is an intermittent, abrupt, involuntary contraction of the diaphragm resulting in sudden inspiration abruptly opposed by the closure of the glottis. Persistent hiccups can interfere with daily activities and cause sleep disturbance and fatigue. We report a case of persistent hiccups occurring in a heart and lung transplant recipient that was successfully treated with acupuncture.

Characteristics of aerosols collected in central Taiwan during an Asian dust event in spring 2000

Aerosol samples for PM(2.5) and PM(2.5-10) were collected at four locations in central Taiwan from 26 to 31 March 2000, a period that experienced exceedingly high PM levels from 29 to 30 March due to the passage of an Asian dust storm. The samples were analyzed for mass, metallic elements, ions, and carbon. The purpose of this paper is to investigate the influence of the dust storm on the characteristics of local ambient particulate matter. The results indicate that the concentrations of the crustal elements Ca, Mg, Al, Fe and the sea salt species Na+ and Cl- in PM(2.5-10) during the dust episode exceed the mean concentrations in the non-dust period by factors of 3.1, 2.9, 2.6, 2.2, 2.3 and 2.1 respectively. Enrichment factors of Ca, Fe, and Mg in PM(2.5-10) during the dust event are close to unity, indicating that these elements are from soil. Reconstruction of aerosol compositions revealed that soil of coarse particulates elevated approximately 50% in the dust event. It is noted that during the dust event, the ratio of Mg/Al in PM(2.5-10) ranged from 0.21 to 0.25 while that of Ca/Al ranged from 0.6 to 0.9, levels more constant than those obtained in non-dust period.

Latent membrane protein-1 of Epstein - Barr virus increases sensitivity to arsenic trioxide-induced apoptosis in nasopharyngeal carcinoma cell

BACKGROUND AND AIM

Epstein - Barr virus (EBV)-encoded LMP1 is suggested to have an important role in the pathogenesis and development of nasopharyngeal carcinoma (NPC). Our previous study showed that As2O3 exhibited growth inhibition of NPC in animal model. Here, we further explore whether LMP1 is involved in As2O3 anticancer effects in NPC cell line.

METHODS

Both the stable expressing LMP1 cell line HNE1-LMP1 and its parental cell line HNE1 without LMP1 expression were used as in vitro models to assess arsenic trioxide effect. Both cell lines were treated with As2O3 for 72 h. The median inhibition concentration (IC50) was assessed by the MTT assay. Apoptosis was observed by phase-contrast microscopy and TUNEL staining. The alteration of telomere lengths was detected by Southern blotting.

RESULTS

IC50 for As2O3 in HNE1-LMP1 cells and HNE1 cells was 2.22 and 5.09 micromol/L, respectively. After exposure to 2 and 4 micromol/L As2O3 for 72 h, the apoptotic index in HNE1-LMP1 was 26.27 -/+ 1.3 and 49.13 -/+ 1.4%, respectively. On the contrary, in HNE1 cells the apoptotic index was 12.6 -/+ 0.9 and 33.20 -/+ 1.3%, respectively. As compared with parental cell line HNE1, HNE1-LMP1 cells were more sensitive to growth inhibition and apoptosis (p < 0.001). The elongation of telomere length was also found in HNE1-LMP1 cells. Meanwhile, longer telomeres in HNE1-LMP1 cells failed to maintain telomere stabilization, instead, it prone to be shortened when exposure to As2O3, as comparing with HNE1 cells.

CONCLUSION

LMP1 plays important role in enhancing NPC cell response to As2O3. The elongation of telomere length induced by LMP1 may contribute to the mechanisms of As2O3 sensitivity.

Correlations of androgen deficiency with clinical symptoms in Taiwanese males

The purpose of this study was to elucidate correlations between different biochemical measurements of androgen deficiency and clinical symptoms in male residents of Taiwan. An investigation of the serum biochemical markers for androgen deficiency in 650 males, including total testosterone, calculated free testosterone, and bioavailable testosterone, was conducted. Measurements of clinical symptoms were obtained using a questionnaire of the androgen deficiency in the aging male (ADAM) by St Louis University (SLQ). Correlations among the biochemical markers, correlations of the biochemical markers and age, and relationships between the biochemical markers and the SLQ were evaluated. The sensitivity and specificity of the SLQ were determined. Bioavailable and calculated free testosterone correlated better with age than did total testosterone. Eighty percent of the men had a positive SLQ, and 20% had a negative SLQ. The percentage of positive SLQ results increased with age. No statistically significant difference was noted between the biochemical markers of bioavailable and calculated free testosterone levels and the SLQ status except for men aged over 70 years. The SLQ in this study showed an acceptable sensitivity of about 80%, but the specificity was poor (about 20%). In conclusion, bioavailable testosterone and calculated free testosterone were more-closely correlated with age and may be better biochemical markers for androgen deficiency. SLQ might not be a suitable single measurement for androgen deficiency and should be used together with biochemical markers.

Use of Complementary and Alternative Medicine in Pediatric Pain Management Service: A Survey: Table 1

OBJECTIVE

To survey the use of complementary and alternative medical therapies by pediatric pain management services affiliated with major universities.

DESIGN

A telephone survey was conducted of pediatric anesthesia training programs accredited by the Accreditation Council for Graduate Medical Education in the United States. The survey instrument included questions on the provision of complementary and alternative medical therapies in their pediatric pain programs.

RESULTS

Forty-three pediatric anesthesia fellowship programs (100%) responded to the survey. Thirty-eight institutions (86%) offered one or more complementary and alternative medical therapies for their patients. Those therapies included biofeedback (65%), guided imagery (49%), relaxation therapy (33%), massage (35%), hypnosis (44%), acupuncture (33%), art therapy (21%), and meditation (21%).

CONCLUSIONS

This report documents trends in complementary and alternative medical therapies usage in the tertiary pediatric pain management service. There is a high prevalence in the integration of complementary and alternative medical therapies in pediatric pain management programs. Additional clinical research in the safety and efficacy in complementary and alternative medical therapies for pediatric pain management is urgently needed.

Epidural abscess following epidural analgesia in pediatric patients

Epidural abscess following epidural analgesia is an unusual event especially in pediatric patients. Two patients presented with fever and local signs of infection without neurological deficit on day 4 after the initiation of epidural analgesia. Neuro-imaging studies revealed epidural abscess. Both pediatric patients were treated successfully with intravenous antibiotics. One of the patients' initial MRI was normal. However, the symptoms persisted and a followed-up scan revealed epidural abscess. The other patient presented with worsening local indurations over the epidural insertion site and positive blood culture with Hemolytic streptococcus. Our experience suggests that neuro-imaging study should be strongly considered to evaluate pediatric patients with suspicion of epidural abscess.

Emergency management and infection control in a radiology department during an outbreak of severe acute respiratory syndrome

The World Health Organization classified Taiwan as a serious epidemic-stricken area when the extent of severe acute respiratory syndrome (SARS) in Taiwan became clear. As of 11 July 2003, 671 probable SARS cases had been identified in Taiwan and 7 healthcare workers had died from the disease. Radiographers were easily infected by SARS because they had close contact with suspected or probable cases while conducting chest X-ray examinations. Three radiographers had been infected by the end of May 2003. Because of the impact of SARS on the Radiology Department, the department established a SARS emergency infection control team and re-designed the department's infection-control and emergency-management procedures based on the concept of risk-grade protection. This effort included installing a radiographic room at the fever-screening station, re-allocating human resources in the Radiology Department, training the department staff in infection control, and drafting new operational procedures for radiographers conducting X-ray examinations on SARS patients. The goal of this program was to reduce the infection rate and distribute materials efficiently in the department. This article introduces the emergency-management procedure of the Radiology Department during the SARS outbreak and the infection-protection experience of the department staff.

Immunohistochemical diagnosis of mouse hepatitis virus and mycoplasma pulmonis infection with murine antiserum

This study established a modified alkaline phosphatase-labelled avidin-biotin-complex (ABC-AP) method for diagnosis of mouse hepatitis virus (MHV) and Mycoplasma pulmonis infection from formalin-fixed, paraffin wax-embedded sections, murine antibody-positive serum being used as the primary reagent. With this method, MHV antigen in cAnNCrj.Cg-Foxn1(nu)/Foxn1(nu) mice and M. pulmonis antigen in Wistar rats were immunolabelled in tissue sections. MHV antigen was clearly detected in samples of liver, stomach, caecal and colonic mucosa, and spleen. M. pulmonis antigen was demonstrated on the luminal surface of bronchiolar epithelial cells. This method may prove useful in diagnosis when commercial antisera are unavailable or when immunosuppression prevents serological diagnosis.

Studies in NZB IL-10 knockout mice of the requirement of IL-10 for progression of B-cell lymphoma

NZB mice develop an age-related malignant expansion of a subset of B cells, B-1 cells, with autocrine production of IL-10. IL-10, a pleiotropic cytokine with anti-inflammatory properties, is a potent growth and survival factor for malignant B cells. To further examine the in vivo requirement for IL-10 in the development and expansion of malignant B-1 clones in NZB mice, we developed a strain of homozygous IL-10 knockout (KO) mice on an NZB background. The NZB IL-10 KO mice develop peritoneal B-1 cells with approximately the same frequency as heterozygous and wild-type littermates. In contrast, the development of malignant B-1 cells in the peripheral blood and spleen, observed in wild-type NZB, rarely occurred in the NZB IL-10 KO. Phenotypic analysis of surface marker expression in splenic B cells indicated that, in contrast to the NZB with malignant B-1 splenic lymphoma, the surface marker expression of NZB IL-10 KO splenic B cells indicated that the majority of the B cells were typical B-2 cells. In the absence of IL-10, spontaneously activated B cells and antiapoptotic gene expression were reduced and lymphoma incidence was decreased. These results indicate that IL-10 is a critical factor for the progression of this B-cell malignant disease.

Induction of VX2 carcinoma in rabbit liver: comparison of two inoculation methods

Direct injection of VX2 cell suspension into the liver is simple and widely used. Implantation of a fragment of VX2 tumour into the liver using a surgical technique has also been developed in the last decade. In this study, we compared these two methods in order to find a better modality for establishing VX2 liver mass. Forty rabbits, each weighing 2.8-3.2 kg, were divided into two groups, 20 rabbits in each. In Group 1, a tumour cell suspension containing 1 x 10(6) cells in a volume of 0.1 ml, was injected slowly into the liver parenchyma using a 27-gauge needle during laparotomy. In Group 2, a 1 mm(3) fragment of VX2 carcinoma was inoculated into the sub-capsule of the left anterior lobe of the liver. In Group 1, three rabbits showed no tumour growth and 10 rabbits showed evidence of leakage and tumour seeding outside of the liver. In Group 2, all but one rabbit showed tumour growth and none showed evidence of tumour seeding. The leakage rates were 50% and 0% for Group 1 and Group 2, respectively. Overall, the success inoculation rate was 35% for Group 1 and 95% for Group 2. In conclusion, to create the VX2 liver tumour model in rabbits, direct implantation of VX2 tumour fragment into the liver achieved better results than injecting cell suspension of VX2 tumour into the liver.

The use of herbs and complementary and alternative medicine in pediatric preoperative patients

STUDY OBJECTIVE

To determine the use of herbs and complementary and alternative medicine among a pediatric preoperative population.

DESIGN

Prospective, consecutive clinical study and survey questionnaire.

SETTING

Children's Hospital pediatric preoperative clinic.

MEASUREMENTS AND MAIN RESULTS

A total of 1,100 surveys were distributed to pediatric patients under the age of 18 years during their preoperative visit over an 8-month period. The survey consisted of a questionnaire about the use of herbs and complementary and alternative therapies within 1 year before the anticipated surgery. The patient or legal guardian was asked whether the patient had tried any of the complementary and alternative medical therapies within 1 year before the scheduled surgical procedure. Of 1,021 completed surveys received, 29.5% of these patients indicated they had tried one or more complementary and alternative therapies in the past year before the surgery, and 12.8% of the pediatric patients used herbal remedies before the surgery.

CONCLUSIONS

Herbs and complementary and alternative medical therapies are frequently used in pediatric populations. Anesthesiologists need to be aware the usage of various herbal supplements in pediatric patients. It is important then to determine the potential of drug and anesthetic interactions in the perioperative period.

Effects of seasonal variation in precipitation on estimation of non-point source pollution

The extent of nonpoint source pollution (NPSP) generated from upstream catchment areas of a reservoir is normally estimated based on a design rainfall. However, rainfall generally varies in different seasons. This seasonal change may significantly influence the estimation of runoff volume and associated NPSP arising within a reservoir watershed. The NPSP management, reservoir operation, and water treatment operation strategies developed based on the estimation will also be altered. This study analyzes the effects of monthly and seasonal variation in precipitation on the estimation of pollution levels from nonpoint sources in a reservoir watershed. The area studied is the Derchi reservoir watershed located in central Taiwan. This watershed is subdivided into twenty-six sub-watersheds, and the Thiessen method is used to determine the rainfall intensity in each sub-watershed. Runoff pattern and NPSP contributions for each sub-watershed are estimated using the AGNPS model. Results show significant seasonal variation in precipitation; estimated NPSP loads likewise vary significantly over time. Seven- to one hundred-fold differences among monthly and seasonal estimations of phosphorus and sediment loads are observed.

Characterization of high-sensitivity metal oxide semiconductor field effect transistor dosimeters system and LiF:Mg,Cu,P thermoluminescence dosimeters for use in diagnostic radiology

Monitoring radiation exposure during diagnostic radiographic procedures has recently become an area of interest. In recent years, the LiF:Mg,Cu,P thermoluminescence dosimeter (TLD-100H) and the highly sensitive metal oxide semiconductor field effect transistor (MOSFET) dosimeter were introduced as good candidates for entrance skin dose measurements in diagnostic radiology. In the present study, the TLD-100H and the MOSFET dosimeters were evaluated for sensitivity, linearity, energy, angular dependence, and post-exposure response. Our results indicate that the TLD-100H dosimeter has excellent linearity within diagnostic energy ranges and its sensitivity variations were under 3% at tube potentials from 40Vp to 125kVp. Good linearity was also observed with the MOSFET dosimeter, but in low-dose regions the values are less reliable and were found to be a function of the tube potentials. Both dosimeters also presented predictable angular dependence in this study. Our findings suggest that the TLD-100H dosimeter is more appropriate for low-dose diagnostic procedures such as chest and skull projections. The MOSFET dosimeter system is valuable for entrance skin dose measurement with lumbar spine projections and certain fluoroscopic procedures.

Acetaminophen developmental pharmacokinetics in premature neonates and infants: a pooled population analysis

BACKGROUND

The aim of this study was to describe acetaminophen developmental pharmacokinetics in premature neonates through infancy to suggest age-appropriate dosing regimens.

METHODS

A population pharmacokinetic analysis of acetaminophen time-concentration profiles in 283 children (124 aged < or = 6 months) reported in six studies was undertaken using nonlinear mixed-effects models. Neonates and infants were given either single or multiple doses of four different formulations: oral elixir, rectal solution, or triglyceride or capsular suppository. The median postnatal age of children younger than 6 months was 1 day (range, birth to 6 months), median postconception age was 40 weeks (range, 28-64 weeks), and median weight was 3.1 kg (range, 1.2-9.0 kg).

RESULTS

Population pharmacokinetic parameter estimates and their variability (percent) for a one-compartment model with first-order input, lag time, and first-order elimination were as follows: volume of distribution, 66.6 l (20%); clearance, 12.5 l/h (44%); standardized to a 70-kg person using allometric "1/4 power" models. The volume of distribution decreased exponentially with a maturation half-life of 11.5 weeks from 109.7 l/70 kg at 28 weeks after conception to 72.9 l/70 kg by 60 weeks. Clearance increased from 28 weeks after conception (0.74 l x h(-1) x 70 kg(-1)) with a maturation half-life of 11.3 weeks to reach 10.8 l x h(-1) x 70 kg(-1) by 60 weeks. The absorption half-life for the oral elixir preparation was 0.21 h (120%) with a lag time of 0.42 h (70%), but absorption was further delayed (2 h) in premature neonates in the first few days of life. Absorption half-life parameters for the triglyceride base and capsule suppositories were 0.80 h (100%) and 1.4 h (57%), respectively. The absorption half-life for the rectal solution was 0.33 h. Absorption lag time was negligible by the rectal route for all three formulations. The bioavailability of the capsule suppository relative to elixir decreased with age from 0.92 (22%) at 28 weeks after conception to 0.86 at 2 yr of age, whereas the triglyceride base decreased from 0.86 (35%) at 28 weeks postconception to 0.5 at 2 yr of age. The relative bioavailability of the rectal solution was 0.66.

CONCLUSIONS

A mean steady state target concentration greater than 10 mg/l at trough can be achieved by an oral dose of 25 mg x kg(-1) x d(-1) in premature neonates at 30 weeks' postconception, 45 mg x kg(-1) x d(-1) at 34 weeks' gestation, 60 mg x kg(-1) x d(-1) at term, and 90 mg x kg(-1) x d(-1) at 6 months of age. The relative rectal bioavailability is formulation dependent and decreases with age. Similar concentrations can be achieved with maintenance rectal doses of 25 (capsule suppository) or 30 (triglyceride suppository) mg. kg-1. d-1 in premature neonates at 30 weeks' gestation, increasing to 90 (capsule suppository) or 120 (triglyceride suppository) mg x kg(-1) x d(-1) at 6 months. These regimens may cause hepatotoxicity in some individuals if used for longer than 2-3 days.

Management of esophageal strictures in children with recessive dystrophic epidermolysis bullosa

BACKGROUND

Recessive dystrophic epidermolysis bullosa is a rare, genetically transmitted skin disorder characterized by blister formation and scarring in response to minor trauma. One of the most debilitating features of the disease is the development of esophageal strictures, which produces profound dysphagia, exacerbating an already highly compromised nutritional status common to these patients. Due to the extreme fragility of epithelial surfaces, the optimal therapeutic approach to esophageal strictures in this setting has not been established.

METHODS

We have developed an approach to treatment of esophageal strictures in children with epidermolysis bullosa combining upper endoscopy using small caliber endoscopes, endotracheal intubation, and fluoroscopically assisted balloon dilatation. We report our experience using this technique in 22 children who have undergone a total of 109 dilatations.

RESULTS

Upper endoscopy, endotracheal intubation, and balloon dilatation were well tolerated by even very young children with epidermolysis bullosa. Dysphagia was markedly reduced post-procedure, permitting resumption of normal diet for age, including solids, within six hours of the procedure. Post-procedure recovery has been rapid and does not require admission to the hospital. Complications have been infrequent, minor, and limited to the first year of our experience. The mean interval between dilatations for all children is 11 months. All children have gained weight, and have not required steroids or phenytoin.

CONCLUSIONS

Balloon dilatation is a safe and effective therapy for esophageal strictures in children with recessive dystrophic epidermolysis bullosa. Limited upper endoscopy and endotracheal intubation are well tolerated by these children. This approach should be considered as primary therapy in this clinical setting.

Assessing the effect of sampling strategies on the power of linkage analysis to identify pathway-specific loci underlying a complex disease

Using the simulated general population data sets, we first examined the effect of sampling strategies on the power of identifying linkage by selecting samples with (A) two affected sibs in a nuclear family and (B) one affected sib and one sib with an intermediate trait value in the upper quantiles. Second, we evaluated the improvement in power when analyzing correlated traits simultaneously. Under each selection criteria, 100 replicates of 300 nuclear families were sampled and analyzed with two-point linkage analysis for ten markers (1 cM apart) from each of the candidate regions. Different genes were identified under different sampling strategies. When a gene has a pleitropic effect, it is more powerful to analyze correlated traits simultaneously, either by using a linear combination or the larger value of standardized traits, than to analyze each trait separately.