Tuning methods for multigap drift tube linacs.

Multigap cavities are used extensively in linear accelerators to achieve velocities up to a few percent of the speed of light, driving nuclear physics research around the world. Unlike for single-gap structures, there is no closed-form expression to calculate the output beam parameters from the cavity voltage and phase. To overcome this, we propose to use a method based on the integration of the first and second moments of the beam distribution through the axially symmetric time-dependent fields of the cavity. A beam-based calibration between the model's electric field scaling and the machine's rf amplitudes is presented, yielding a fast online energy change method, returning cavity amplitude and phase necessary for a desired output beam energy and energy spread. The method is validated with 23Na6+ beam energy measurements.

Germline mutations of the STK11 gene in Korean Peutz-Jeghers syndrome patients.

Peutz-Jeghers syndrome (PJS) is an autosomal dominantly inherited disease characterized by hamartomatous gastrointestinal polyps and mucocutaneous pigmentation, with an increased risk for various neoplasms, including gastrointestinal cancer. Recently, the PJS gene encoding the serine/threonine kinase STK11 (also named LKB1) was mapped to chromosome 19p13.3, and germline mutations were identified in PJS patients. We screened a total of ten Korean PJS patients (nine sporadic cases and one familial case including two patients) to investigate the germline mutations of the STK11 gene. By polymerase chain reaction-single-strand conformation polymorphism and DNA sequencing analysis, three kinds of mis-sense mutation and a frame-shift mutation were identified: codon 232 (TCC to CCC) in exon 5, codon 256 (GAA to GCA) in exon 6, codon 324 (CCG to CTG) in exon 8, and a guanine insertion at codon 342 resulting in a premature stop codon in exon 8. These mis-sense variants were not detected in 100 control DNA samples. Furthermore, we found an intronic mutation at the dinucleotide sequence of a splice-acceptor site: a one base substitution from AG to CG in intron 1, which may cause aberrant splicing. Most reported germline mutations of the STK11 gene in PJS patients were frame-shift or non-sense mutations resulting in truncated proteins. Together, these findings indicate that germline mis-sense mutations of the STK11 gene are found in PJS patients in addition to truncating mutations. The effects of these mutations on protein function require further examination. In summary, we found germline mutations of the STK11 gene in five out of ten Korean PJS patients.

Clinical characteristics of Peutz-Jeghers syndrome in Korean polyposis patients.

Peutz-Jeghers syndrome is an autosomal dominant inherited disorder characterized by hamartomatous polyps in the small bowel and mucocutaneous pigmentation. Patients with Peutz-Jeghers syndrome often present as surgical emergencies with complications of the polyps, such as intussusception, bowel obstruction, and bleeding. Recently an increased risk of malignancies has also been reported. This study was initiated to determine the clinical features of Peutz-Jeghers syndrome in Korean patients, with special attention to the development of malignancies. Thirty patients with Peutz-Jeghers syndrome were investigated; their median age was 23.5 years, and symptoms appeared at a median age of 12.5 years. Family history was positive in one-half of cases, and mucocutaneous pigmentation was observed in almost all patients (93%). The jejunoileum was the most frequent site of the polyps, and there were generally 10-100 polyps. Multiple laparotomies were performed in a substantial portion of the patients, due mainly to polyp-induced bowel obstruction, and the surgical interventions were begun at a relatively young age (average 21.4 years). Four cases of small-bowel cancer and one case of breast cancer were detected in probands, at a relatively young age (mean 36 years). Cancers of the small bowel, stomach, colon, breast and cervix were diagnosed in the first relatives of the probands. Close follow-up from an early age should thus be performed in patients with Peutz-Jeghers syndrome as they are at high risk of surgical emergency and development of malignancy.

3'-Beta-ethynyl and 2'-deoxy-3'-beta-ethynyl adenosines: first 3'-beta-branched-adenosines substrates of adenosine deaminase.

The 3'-C-branched-adenosine and 2'-deoxyadenosine analogues 1-7 were tested as substrate of adenosine deaminase. The 9-(3'-C-ethynyl-beta-D-ribo-pentofuranosyl)adenine 1 and its 2'-deoxy analogue 7 were deaminated by the enzyme while the vinyl and ethyl derivatives 2 and 3 were not. The 9-(3'-C-branched-beta-D-xylo-pentofuranosyl)adenines 4-6 were deaminated by the deaminase.

Effect of ceramide on apoptosis and phospholipase D activity in FRTL-5 thyroid cells.

Ceramide, a product of sphingomyelin hydrolysis, is now recognized as an intracellular lipid messenger, which mediates the effects of extracellular agents on cellular growth, differentiation and apoptosis. Recently, ceramide has been implicated in the regulation of phospholipase D (PLD). In this study, we examined the effects of ceramide on the activity and mRNA level of PLD during apoptotic process in FRTL-5 thyroid cells. C2-ceramide (N-acetyl sphingosine) induced apoptosis in FRTL-5 thyroid cells. Fluorescent staining showed that ceramide induced the typical features of apoptosis including condensed or fragmented nuclei. DNA fragmentation was also observed by agarose gel electrophoresis. Flow cytometric cell cycle analysis showed more clearly that ceramide induced apoptotic cell death in FRTL-5 thyroid cells. The treatment of FRTL-5 thyroid cells with thyroid-stimulating hormone (TSH) resulted in an increased PLD activity in a dose- and time-dependent manner. However, the TSH-induced increase in PLD activity was down-regulated within 2 h after ceramide treatment. Furthermore, the levels of PLD mRNA were found to be decreased throughout apoptotic process as inferred by reverse transcription-polymerase chain reaction. However, the decreases in PLD mRNA levels were not correlated with those in PLD activities after ceramide treatment. Taken together, these data suggest that ceramide inhibits the PLD activity in an early apoptotic phase and down-regulation of the levels of PLD mRNA may be implicated in apoptotic process in FRTL-5 thyroid cells.

Multiple intestinal ulcerations and perforations secondary to methicillin-resistant Staphylococcus aureus enteritis in infants.

PURPOSE: The aim of this study was to define a distinctive clinical entity of multiple intestinal ulcerations and perforations in infants. METHODS: Two infants underwent abdominal exploration for surgical abdomen and were noted to have multiple intestinal ulcerations and perforations. A peculiar and unique surgical finding, numerous transverse linear ulcerations scattered along the entire small intestine, prompted us to search for similar instances. Five similar cases were additionally identified by members of the Korean Association of Pediatric Surgeons. The clinical courses, the surgical findings, and the results of bacterial cultures were reviewed. As well, the tissues of resected intestines were examined histopathologically. RESULTS: The characteristics of this entity are as follows. (1) It usually occurs in infants who have been treated with broad-spectrum antibiotics. (2) Despite broad-spectrum antibiotic treatment, diarrhea and abdominal distension developed progressively and deteriorated. (3) Histological evaluation showed mucosal ulcers with neutrophil infiltration, submucosal microabscesses, and colonies of Gram-positive cocci. (4) Methicillin-resistant Staphylococcus aureus (MRSA) was the predominant organism cultured from the body fluid. (5) Only two cases, the completely resected one and the one immediately treated postoperatively with vancomycin, survived. CONCLUSIONS: This entity is caused by multiple intestinal ulcerations and perforations secondary to MRSA enteritis in infants. It has a high mortality rate because of its difficult diagnosis. However, early recognition of this entity can lead to successful treatment.

Successful separation of thoraco-omphalopagus and ischiopagus tetrapus twins in Korea.

A pair of male thoraco-omphalopagus twins with common liver, diaphragm, pericardium, and sternum was separated at the age of 59 days after a parasitic relationship had developed between them. Before separation one baby developed acute renal failure during which he had no edema and had normal serum electrolytes, urea nitrogen, and creatinine due to "autodialysis" by the other baby. The boys have now grown normally to the age of 6 years. A pair of female ischiopagus tetrapus twins who had a common terminal ileum and colon with imperforate anus was separated at the age of 20 h. The smaller baby had congenital multiple arthrogryposis of both lower extremities, a fracture at the middle of the left femur, and a double vagina with hydrocolpos due to an imperforate hymen of the right vagina and a rectovaginal fistula on the left. Posterior sagittal rectoplasties were performed at 7 months of age in both babies. They have normal bowel movements. All four children are alive and developing normally. These are the first two case reports of successfully separated conjoined twins in Korea.

Hirschsprung's disease: one surgeon's experience in one institution.

The clinical experience of 137 patients treated by one pediatric surgeon at HanYang University Hospital over 12 years was analyzed. The sex ratio was 3.6:1 with male predominance. Neonatal Hirschsprung's disease (HD) occurred in 70 cases (51.1%). One hundred fourteen cases (83.2%) were short-segment and 23 cases (16.8%) were long-segment disease, of which 4 cases were total colon aganglionosis. Symptoms were abdominal distension, vomiting, constipation, and delayed passage of meconium. Family history was noted in 4 cases: 3 involved siblings and 1 involved relatives. All patients were male and had short-segment diseases. There were 3 pairs of monozygotic twins discordant for HD. Seventy-seven two-stage Duhamel operations were performed at the age of 121 +/- 41.3 days. Primary Duhamel operations were performed on 30 children. Anorectal myectomies were performed on 12 cases of short rectal aganglionosis. The incidence of enterocolitis was 25.5% preoperatively and 10.1% postoperatively. Complications after the Duhamel operation were intestinal obstruction (3), wound disruption (4), and septum reformation (3) with fecaloma formation in the blind rectal pouch. Bowel function was normalized within 3 months in 77.3% and within 1 year after operation in 91.6%. Duhamel operation with a GIA stapler after preliminary colostomy could be done at the age of 104 days on average with good functional results and with acceptable morbidity. Primary Duhamel operation could be done safely on the patients whose conditions were diagnosed after 90 days of life with good results. There was no mortality after Duhamel operation.

Fibrous hamartoma of infancy manifested as multiple nodules--a case report.

Fibrous hamartoma of infancy is an uncommon benign fibrous proliferation, usually presenting as a solitary nodule. A rare example of multiple fibrous hamartoma of infancy is described. Two masses which developed in the upper arm of a 10-month-old boy were successfully excised, and one month later three small nodules 2 cm below the previous operation field appeared. It will be further elucidated whether multiple forms and early recurrence are related or not as cases accumulate.