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Biomedical subjects

B Chang

Publications and source records attributed to B Chang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evaluation of linkage and association of HPC2/ELAC2 in patients with familial or sporadic prostate cancer.

To investigate the relationship between HPC2/ELAC2 and prostate cancer risk, we performed the following analyses: (1) a linkage study of six markers in and around the HPC2/ELAC2 gene at 17p11 in 159 pedigrees with hereditary prostate cancer (HPC); (2) a mutation-screening analysis of all coding exons of the gene in 93 probands with HPC; (3) family-based and population-based association study of common HPC2/ELAC2 missense variants in 159 probands with HPC, 249 patients with sporadic prostate cancer, and 222 unaffected male control subjects. No evidence for linkage was found in the total sample, nor in any subset of pedigrees based on characteristics that included age at onset, number of affected members, male-to-male disease transmission, or race. Furthermore, only the two previously reported missense changes (Ser217Leu and Ala541Thr) were identified by mutational analysis of all HPC2/ELAC exons in 93 probands with HPC. In association analyses, family-based tests did not reveal excess transmission of the Leu217 and/or Thr541 alleles to affected offspring, and population-based tests failed to reveal any statistically significant difference in the allele frequencies of the two polymorphisms between patients with prostate cancer and control subjects. The results of this study lead us to reject the three alternative hypotheses of (1) a highly penetrant, major prostate cancer-susceptibility gene at 17p11, (2) the allelic variants Leu217 or Thr541 of HPC2/ELAC2 as high-penetrance mutations, and (3) the variants Leu217 or Thr541 as low-penetrance, risk-modifying alleles. However, we did observe a trend of higher Leu217 homozygous carrier rates in patients than in control subjects. Considering the impact of genetic heterogeneity, phenocopies, and incomplete penetrance on the linkage and association studies of prostate cancer and on the power to detect linkage and association in our study sample, our results cannot rule out the possibility of a highly penetrant prostate cancer gene at this locus that only segregates in a small number of pedigrees. Nor can we rule out a prostate cancer-modifier gene that confers a lower-than-reported risk. Additional larger studies are needed to more fully evaluate the role of this gene in prostate cancer risk.

Age of Onset↗
PubMed2001

Genetic modification of glaucoma associated phenotypes between AKXD-28/Ty and DBA/2J mice.

BACKGROUND: Glaucoma is a common disease but its molecular etiology is poorly understood. It involves retinal ganglion cell death and optic nerve damage that is often associated with elevated intraocular pressure. Identifying genes that modify glaucoma associated phenotypes is likely to provide insights to mechanisms of glaucoma. We previously reported glaucoma in DBA/2J mice caused by recessive alleles at two loci, isa and ipd, that cause iris stromal atrophy and iris pigment dispersion, respectively. A approach for identifying modifier genes is to study the effects of specific mutations in different mouse strains. When the phenotypic effect of a mutation is modified upon its introduction into a new strain, crosses between the parental strains can be used to identify modifier genes. The purpose of this study was to determine if the effects of the DBA/2J derived isa and ipd loci are modified in strain AKXD-28/Ty. RESULTS: AKXD-28/Ty mice develop glaucoma characterized by intraocular pressure elevation, retinal ganglion loss, and optic nerve excavation. In AKXD-28/Ty, isa causes an iris stromal atrophy phenotype as in DBA/2J. However, the iris pigment dispersion phenotype associated with ipd in DBA/2J does not occur in AKXD-28/Ty. Additionally, a greater severity and speed of retinal and optic nerve damage following intraocular pressure elevation in AKXD-28/Ty compared to DBA/2J mice suggests that AKXD-28/Ty is more susceptible to pressure-induced cell death. CONCLUSIONS: The consequences of the ipd and isa mutations are modified in the AKXD-28/Ty background. These strains provide a resource for the identification of modifier genes that modulate pigment dispersion and susceptibility to pressure-induced cell death.

Animals↗
PubMed2001

Linkage of prostate cancer susceptibility loci to chromosome 1.

Three prostate cancer susceptibility genes have been reported to be linked to different regions on chromosome 1: HPC1 at 1q24-25, PCAP at 1q42-43, and CAPB at 1p36. Replication studies analyzing each of these regions have yielded inconsistent results. To evaluate linkage across this chromosome systematically, we performed multipoint linkage analyses with 50 microsatellite markers spanning chromosome 1 in 159 hereditary prostate cancer families (HPC), including 79 families analyzed in the original report describing HPC1 linkage. The highest lod scores for the complete dataset of 159 families were observed at 1q24-25 at which the parametric lod score assuming heterogeneity (hlod) was 2.54 (P=0.0006) with an allele sharing lod of 2.34 (P=0.001) at marker D1S413, although only weak evidence was observed in the 80 families not previously analyzed for this region (hlod=0.44, P=0.14, and allele sharing lod=0.67, P=0.08). In the complete data set, the evidence for linkage across this region was very broad, with allele sharing lod scores greater than 0.5 extending approximately 100 cM from 1p13 to 1q32, possibly indicating the presence of multiple susceptibility genes. Elsewhere on chromosome 1, some evidence of linkage was observed at 1q42-43, with a peak allele sharing lod of 0.56 (P=0.11) and hlod of 0.24 (P=0.25) at D1S235. For analysis of the CAPB locus at 1p36, we focused on six HPC families in our collection with a history of primary brain cancer; four of these families had positive linkage results at 1p36, with a peak allele sharing lod of 0.61 (P=0.09) and hlod of 0.39 (P=0.16) at D1S407 in all six families. These results are consistent with the heterogeneous nature of hereditary prostate cancer, and the existence of multiple loci on chromosome 1 for this disease.

Chromosome Mapping↗
PubMed2001

Evidence for a prostate cancer linkage to chromosome 20 in 159 hereditary prostate cancer families.

Prostate cancer is the most common malignancy diagnosed in men in the US. Genetic susceptibility to prostate cancer has been well documented. A region at chromosome 20q13 (HPC20) has been reported to be linked to a prostate cancer susceptibility gene. To confirm this finding, we genotyped 16 markers spanning approximately 95 cM on chromosome 20 in 159 hereditary prostate cancer (HPC) families. Positive (but not statistically significant) linkage scores were observed from 20pter to 20q11, with the highest non-parametric linkage (NPL) score for the complete dataset of 1.02 (P=0.15) being observed at D20S195 at 20q11. Evidence for linkage from parametric analyses with a dominant or a recessive model was weak. Interestingly, consistent with the original findings of linkage to 20 g higher linkage scores were observed in the subsets of families with a later age at diagnosis (> or =65 years; n=80, NPL=1.94, P=0.029 at D20S186), fewer than five affected family members (n=69, NPL=1.74, P=0.037 at D20S889), or without male-to-male disease transmission (n=60, NPL=1.01, P=0.15 at D20S117). The region with positive linkage scores spanned approximately 60 cM from 20pter to 20q11 in these subsets of families. Our results are consistent with a prostate cancer susceptibility locus on chromosome 20.

Aged↗
PubMed2001

Primary retroperitoneal seminoma with utrasonically abnormal testes.

Primary retroperitoneal seminomas account for approximately 2% of all seminomas. Differentiating the primary retroperitoneal tumor from a metastatic tumor with an occult testicular primary remains difficult despite the availability of ultrasonic examination. We present a case of primary retroperitoneal seminoma with ultrasonically demonstrated abnormalities in both testes. The patient underwent a unilateral orchiectomy and ultrasound-guided biopsy of the opposite testis. All surgical specimens were negative for testis cancer. Controversial issues in the diagnosis and treatment of primary retroperitoneal germ cell tumors are discussed.

Adult↗
PubMed2001

Laparoscopic orchidopexy: a review of a large clinical series.

OBJECTIVE: To report the overall success rate of a laparoscopic orchidopexy (LO) series over 5 years including over 100 procedures. PATIENTS AND METHODS: The records were reviewed of children who underwent laparoscopic procedures for an impalpable testis at our institutions. The laparoscopic procedures included the standard LO and one-stage and staged Fowler-Stephens (F-S) LOs. The success of orchidopexy was defined as a testis in the scrotum with no atrophy after surgery. RESULTS: From 1994, 80 children (101 impalpable testes) were treated using LO. Of these patients, 20 (25%) had impalpable testes on the right, 39 (50%) were on the left and 21 (25%) were bilateral. The testicular location was identified during laparoscopy as: intra-abdominal in 46, iliac in 14, in the internal ring in 22, 'peeping' in 12, behind the bladder in three and intracanulicular in four. Standard LO was used in 72 testes, a one-stage F-S in 20 and a two-stage F-S in nine (first stage two, second stage seven). The median (range) age of the patients was 18 months (0.5-12 years); the mean (range) follow-up was 5 (1-36) months. After orchidopexy the testis was scrotal in 90 (low 78, mid four and high eight), at the pubis in one and not stated in seven (no follow-up available). Four patients (4%) had testicular atrophy from failed F-S orchidopexies, two of whom had undergone previous testicular surgery and one caused by additional dissection around the vas. The overall success rate, including only those with follow-up, was 96% (90 of 94). Of the 20 one-stage F-S orchidopexies, 17 testes were successfully placed in the scrotum with no atrophy. The overall success rate for all F-S procedures was 85% (23 of 27). However, excluding patients who had previous testicular surgery or who required extensive dissection near the vas, 96% (23 of 24) of the testes were successfully placed into the scrotum with no atrophy. CONCLUSION: The high overall success rate in placing the testis into the scrotum through laparoscopic procedures is considerably better than reported in other series to date. LO is an effective method for managing intra-abdominal testes in children. Patients who had undergone previous surgery had a higher risk of developing testicular atrophy. The additional dissection around the vas almost inevitably leads to testicular atrophy.

Ambulatory Surgical Procedures↗
PubMed2001

Underappreciation of sleep disorders as a cause of motor vehicle crashes.

Despite an increased risk of motor vehicle crashes (MVC) in patients with obstructive sleep apnea (OSA), we hypothesized that OSA was not considered in drivers admitted to trauma centers after an injury-producing MVC. A retrospective study on drivers involved in MVCs admitted to a level 1 trauma center was performed, with crash cause determined and the frequency of sleep studies recorded. A questionnaire was also mailed to 240 trauma centers seeking information on evaluation of patients with unexplained causes for MVCs, including screening for OSA. There were 122 drivers of MVCs admitted to our hospital, 60/122 (49%) had unexplained crashes and no sleep studies were performed. There were 70 survey respondents (30% return rate), 35/70 (50%) centers routinely screened for syncope after unexplained MVC, however, no center screened for OSA. US trauma centers do not screen for sleep disorders despite the associated increased crash risk and the high prevalence of crashes that can not be explained by other causes. We believe this reflects a lack of awareness of sleep disorders by health care professionals caring for trauma victims and education is of utmost importance.

Accidents, Traffic↗
PubMed2001

Ultraviolet-assisted punch biopsy mapping for lentigo maligna melanoma.

Lentigo maligna melanoma (LMM) accounts for a substantial incidence of all locally recurrent melanoma. In addition, the head and neck area accounts for 60% to 90% of all LMMs, which has important functional and cosmetic implications. The difficulty in the identification of the true borders of LMM may account for the high incidence of local recurrence. The purpose of this study was to evaluate the efficacy of ultraviolet-assisted punch biopsy mapping to identify clear margins using identified, 2-mm circumferentially arranged punch biopsies at the junction of the pigmented and nonpigmented borders. A retrospective chart review of 20 patients with biopsy-confirmed LMM of the head and neck was performed. Using ultraviolet identification, 2-mm circumferentially arranged biopsy specimens were obtained and sent for formal pathological review, including immunohistochemical staining. The average time for completion of pathological review was 5 to 7 days. If the punch biopsies were positive for lentigo maligna or LMM, punch biopsies were obtained more peripherally. Once clear, margins were obtained and definitive resection was performed. Twenty patients with biopsy-proved LMM were evaluated. Follow-up ranged from 6 months to 3 years (mean follow-up, 1 year). Fourteen patients were cleared after their first series of biopsies, 3 patients required a second series of biopsies, 2 patients required a third session, and 1 patient required a fourth biopsy session. To date, there has been no evidence of recurrence. No patients required reexcision for positive surgical margins. One complication has been local cellulitis of a punch biopsy site requiring a short course of antibiotics. Ultraviolet-assisted punch biopsy mapping of LMM is a safe, well-tolerated, and accurate technique for identifying the true histological margin of LMM. The procedure reduces the need for repeat surgical excisions to obtain clear margins and may decrease the risk for recurrence by mapping accurately the true histological margin.

Adult↗
PubMed2001

Treadmill injuries to the upper extremity in pediatric patients.

Injury is the leading cause of preventable death and disability in childhood and early adulthood. Approximately 25,000 children are injured on exercise equipment each year. Although hand injuries sustained on stationary bicycles in the home have been well documented, little has been reported on home treadmill injuries. Between September 1996 and March 2000, the authors treated 12 children at The Children's Hospital of Philadelphia for injuries to the upper extremity sustained on a treadmill. The age at the time of injury ranged from 14 months to 7 years, with a median age of 2.4 years. Average length of follow-up was 11.4 months. Ten of the 12 children sustained partial- or full-thickness burns to the volar aspect of the hand and digits. Overall, 6 patients required surgical repair. A total of 25% of the volar flexion creases involved required surgery. All patients had good functional results. The authors discuss the mechanism of injury, management, and measures to prevent treadmill injuries to children. To their knowledge, this is the first report of such injuries resulting from the use of a treadmill.

Accidents, Home↗
PubMed2001

Penetrating esophageal injuries: multicenter study of the American Association for the Surgery of Trauma.

OBJECTIVE: The purpose of this study was to define the period of time after which delays in management incurred by investigations cause increased morbidity and mortality. The outcome study is intended to correlate time with death from esophageal causes, overall complications, esophageal related complications, and surgical intensive care unit length of stay. METHODS: This was a retrospective multicenter study involving 34 trauma centers in the United States, under the auspices of the American Association for the Surgery of Trauma Multi-institutional Trials Committee over a span of 10.5 years. Patients surviving to reach the operating room (OR) were divided into two groups: those that underwent diagnostic studies to identify their injuries (preoperative evaluation group) and those that went immediately to the OR (no preoperative evaluation group). Statistical methods included Fisher's exact test, Student's T test, and logistic regression analysis. RESULTS: The study involved 405 patients: 355 male patients (86.5%) and 50 female patients (13.5%). The mean Revised Trauma Score was 6.3, the mean Injury Severity Score was 28, and the mean time interval to the OR was 6.5 hours. There were associated injuries in 356 patients (88%), and an overall complication rate of 53.5%. Overall mortality was 78 of 405 (19%). Three hundred forty-six patients survived to reach the OR: 171 in the preoperative evaluation group and 175 in the no preoperative evaluation group. No statistically significant differences were noted in the two groups in the following parameters: number of patients, age, Injury Severity Score, admission blood pressure, anatomic location of injury (cervical or thoracic), surgical management (primary repair, resection and anastomosis, resection and diversion, flaps), number of associated injuries, and mortality. Average length of time to the OR was 13 hours in the preoperative evaluation group versus 1 hour in the no preoperative evaluation group (p < 0.001). Overall complications occurred in 134 in the preoperative evaluation group versus 87 in the no preoperative evaluation group (p < 0.001), and 74 (41%) esophageal related complications occurred in the preoperative evaluation group versus 32 (19%) in the no preoperative evaluation group (p = 0.003). Mean surgical intensive care unit length of stay was 11 days in the preoperative evaluation group versus 7 days in the no preoperative evaluation group (p = 0.012). Logistic regression analysis identified as independent risk factors for the development of esophageal related complications included time delays in preoperative evaluation (odds ratio, 3.13), American Association for the Surgery of Trauma Organ Injury Scale grade >2 (odds ratio, 2.62), and resection and diversion (odds ratio, 4.47). CONCLUSION: Esophageal injuries carry a high morbidity and mortality. Increased esophageal related morbidity occurs with the diagnostic workup and its inherent delay in operative repair of these injuries. For centers practicing selective management of penetrating neck injuries and transmediastinal gunshot wounds, rapid diagnosis and definitive repair should be made a high priority.

Adolescent↗
PubMed2001

Intraocular pressure and pulsatile ocular blood flow after retrobulbar and peribulbar anaesthesia.

AIMS: This study investigated the effect of peribulbar and retrobulbar local anaesthesia on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF), as such anaesthetic techniques may adversely affect these parameters. METHODS: 20 eyes of 20 patients who were to undergo phacoemulsification cataract surgery were prospectively randomised to receive peribulbar or retrobulbar anaesthesia. The OBF tonometer (OBF Labs, Wiltshire, UK) was used to simultaneously measure IOP and POBF before anaesthesia and 1 minute and 10 minutes after anaesthesia. Between group comparisons of age, baseline IOP, and baseline POBF were performed using the non-parametric Mann-Whitney test. Within group comparisons of IOP and POBF measured preanaesthesia and post-anaesthesia were performed using the non-parametric Wilcoxon signed ranks test for both groups. RESULTS: There was no statistically significant IOP increase post-anaesthesia in either group. In the group receiving peribulbar anaesthesia, there was a significant reduction in POBF initially post-anaesthesia which recovered after 10 minutes. In the group receiving retrobulbar anaesthesia, there was a persistent statistically significant reduction in POBF. CONCLUSIONS: Retrobulbar and peribulbar injections have little effect on IOP. Ocular compression is not needed for IOP reduction when using local anaesthesia for cataract surgery. Conversely, POBF falls, at least for a short time, when anaesthesia for ophthalmic surgery is administered via a retrobulbar route or a peribulbar route. This reduction may be mediated by pharmacologically altered orbital vascular tone. It may be safer to use other anaesthetic techniques in patients with ocular vascular compromise.

Aged↗
PubMed2001

Depression in sarcoidosis.

Sarcoidosis, a chronic, multisystem disease, impacts quality of life and may increase depression risk. No previous study has reported the depression prevalence among U.S. sarcoid patients. This cross-sectional study examined sociodemographic and disease morbidity factors associated with depression. Patients diagnosed for > or = 1 yr and treated at one of six centers were eligible (n = 176); 154 completed a questionnaire of demographics, treatment, access to medical care, and a short-form Center for Epidemiologic Studies- Depression Scale (CES-D). The primary outcome variable was a CES-D score of > or = 9, indicating clinical depression. The prevalence of depression was 60%. Gender, income, access to medical care, dyspnea on exertion, and number of systems involved were associated with depression. Female sex, decreased access to medical care, and increased dyspnea predicted depression (odds ratio [OR] = 3.33, 11.64, and 2.78, respectively) after adjusting for race, income, and steroid therapy. Despite tertiary care access, patients reported medical care limitation. Health care providers must be sensitive to multiple barriers faced by chronic sarcoid patients; acknowledging depression risk and improving access to medical care will promote better overall health among sarcoid patients. Future studies of sarcoidosis will need to address depression diagnosis and treatment.

Adult↗
PubMed2001

Evidence for shared genetic programs from cluster analysis of hippocampal gene expression dynamics in development and response to injury.

Cluster analysis is a computational method that groups together similarly-shaped patterns. It may be applied to large-scale gene expression data to form new hypotheses regarding gene function. In the present study, we clustered the temporal expression patterns of genes expressed in the rat hippocampus during normal development and after a kainate-induced seizure injury at postnatal day 25. We found that two different methods, Euclidean hierarchical and K-means clustering, produced slightly different results, and concluded that different clustering methods may he used to complement one another. We also found that certain genes cluster together both during development and after seizure injury, consistent with the idea of sets of genes that act in concert under various conditions.

Animals↗
PubMed2000

A unique and common restriction fragment pattern of the nucleotide sequences homologous to the genome of vf33, a filamentous bacteriophage, in pandemic strains of Vibrio parahaemolyticus O3:K6 O4:K68, and O1:K untypeable.

Vf33 is a filamentous bacteriophage isolated from Vibrio parahaemolyticus. We performed Southern blot hybridization analysis to examine the distribution of Vf33-related genetic elements in the pandemic strains (O3:K6 strains isolated between 1995 and 1997, O4:K68 and O1:K untypeable strains isolated between 1997 and 1999) of V. parahaemolyticus. Nucleotide sequences homologous to the Vf33 DNA were detected in all 57 test strains including pandemic and non-pandemic strains. However, the profiles of hybridization, including the restriction fragment length polymorphism, with nine Vf33-derived DNA probes exhibited by the pandemic strains were identical and were different from those by the non-pandemic strains. The results support the hypothesis that the pandemic strains are clonal, and suggest a possibility that they have acquired (a) new gene(s) via a Vf33-like filamentous phage.

Bacteriophages↗
PubMed2000

[Contamination of a bronchial fiberscope by mycobacteria linked to an automated bronchoscope disinfection machine].

Mycobacteria are being isolated with increasing frequency from automated bronchoscope disinfection machines. This has led to misdiagnosis and nosocomial infections. In this study, we isolated Mycobacterium chelonae from a bronchoscope disinfection machine and found one strain to be resistant to 2% glutaraldehyde and sensitive to 70% ethanol. Since we began cleaning the sink of the machine with 70% ethanol, no mycobacteria has been seen throughout the machine.

Bronchoscopy↗
PubMed2000

A deletion in a photoreceptor-specific nuclear receptor mRNA causes retinal degeneration in the rd7 mouse.

The rd7 mouse, an animal model for hereditary retinal degeneration, has some characteristics similar to human flecked retinal disorders. Here we report the identification of a deletion in a photoreceptor-specific nuclear receptor (mPNR) mRNA that is responsible for hereditary retinal dysplasia and degeneration in the rd7 mouse. mPNR was isolated from a pool of photoreceptor-specific cDNAs originally created by subtractive hybridization of mRNAs from normal and photoreceptorless rd mouse retinas. Localization of the gene corresponding to mPNR to mouse Chr 9 near the rd7 locus made it a candidate for the site of the rd7 mutation. Northern analysis of total RNA isolated from rd7 mouse retinas revealed no detectable signal after hybridization with the mPNR cDNA probe. However, with reverse transcription-PCR, we were able to amplify different fragments of mPNR from rd7 retinal RNA and to sequence them directly. We found a 380-nt deletion in the coding region of the rd7 mPNR message that creates a frame shift and produces a premature stop codon. This deletion accounts for more than 32% of the normal protein and eliminates a portion of the DNA-binding domain. In addition, it may result in the rapid degradation of the rd7 mPNR message by the nonsense-mediated decay pathway, preventing the synthesis of the corresponding protein. Our findings demonstrate that mPNR expression is critical for the normal development and function of the photoreceptor cells.

Amino Acid Sequence↗