Biomedical subjects

S Son

Publications and source records attributed to S Son.

16 recordsLinked to original sources

PubMed2005

Current-drive efficiency in a degenerate plasma.

In a degenerate plasma, the rates of electron processes are much smaller than the classical model would predict, affecting the efficiencies of current generation by external noninductive means, such as by electromagnetic radiation or intense ion beams. For electron-based mechanisms, the current-drive efficiency is higher than the classical prediction by more than a factor of 6 in a degenerate hydrogen plasma, mainly because the electron-electron collisions do not quickly slow down fast electrons. Moreover, electrons much faster than thermal speeds are more readily excited without exciting thermal electrons. In ion-based mechanisms of current drive, the efficiency is likewise enhanced due to the degeneracy effects, since the electron stopping power on slow ion beams is significantly reduced.

Journal Article↗

PubMed2004

[Prevalence of hepatitis A, B, C and E virus markers among patients with elevated levels of Alanine aminotransferase and Aspartate aminotransferase in Phnom Penh (Cambodia) and Nha Trang (Central Vietnam)].

In order to describe the respective part of viral hepatitis in liver diseases observed in Cambodia and Vietnam, ninety consecutive patients with Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) > or = 100 Ul/l were tested for hepatitis A, B, C and E markers in Phnom Penh and Nha Trang. The markers were IgM antibodies to hepatitis A virus (anti-HAV IgM), hepatitis B surface antigen (HBsAg), antibodies to hepatitis C virus (anti-HCVAb) and IgG antibodies to hepatitis E virus (anti-HEV IgG). Recruited patients were predominantly adults and male (sex ratio 76%). Among these patients, 81% were tested positive to at least one marker in Nha Trang and 79% in Phnom Penh. In Nha Trang, HBsAg was more frequent (73%) than anti-HCV Ab (9%) while in Phnom Penh both markers were closely similar (HBsAg: 41%, anti-HCV Ab: 39%). In both population samples, HBsAg was more prevalent among young people whereas anti-HCV Ab were only detected in adults. No case of acute HAV infection was diagnosed in Nha Trang while anti-HAV IgM were detected in 20% of Cambodian patients. Anti-HEV IgG were infrequent (2% in Nha Trang, 5.5% in Phnom Penh). Only one case was notified, a male Vietnamese patient probably suffering from acute hepatitis E. More studies would be useful to improve the control measures against viral hepatitis in the public health programs.

Adolescent↗

PubMed2001

Caffeic acid phenethyl ester (CAPE): synthesis and X-ray crystallographic analysis.

The structure of caffeic acid phenethyl ester [2-propenoic acid, 3-(3,4-dihydroxyphenyl)-, 2-phenethyl ester] (I), C17H16O4 x 1/2C6H6, synthesized by base-catalyzed alkylation of caffeic acid salt with beta-bromoethylbenzene in HMPA (hexamethylphosphoramide) and recrystallized from benzene, was confirmed by single crystal X-ray diffraction. The crystals are triclinic, space group P1, Z=2, unit cell dimension a=5.8129 (9) A, b=11.122 (2) A, c=13.226 (2) A, alpha=97.080 (3) degrees, beta=101.467 (3) degrees, gamma=95.405 (3) degrees , V=825.4 (2) A3, Dcalc=1.301 g/cm3, F(000)=342. The packing of the molecule is stabilized by intermolecular O1H...O4 (2.69 A) and O1...HO2 (2.82 A) hydrogen bonds.

Caffeic Acids↗

PubMed1999

The relationship between gelatinase A activity in aqueous humor and glaucoma.

PURPOSE: To investigate whether abnormal expression of gelatinase A in aqueous humor may be related to the development of glaucoma, the activity of gelatinase A in aqueous humor of patients with glaucoma and patients with cataract was measured and compared. METHODS: Six primary patients with open-angle glaucoma (POAG), four patients with chronic angle closure glaucoma (CACG), four patients with normal tension glaucoma (NTG), and 14 patients with cataract were enrolled. The aqueous humor of each patient was collected during surgery, and total protein concentration and gelatinase activity in the aqueous humor were measured by protein assay kit and zymography, respectively. RESULTS: In patients with POAG, total protein concentration doubled and gelatinase A activity increased by 3.9 times compared with patients with cataract. However, there were no statistically significant differences in total protein concentration and gelatinase A activity in patients with CACG or NTG compared with patients with cataract. CONCLUSION: The development of POAG may be associated with the abnormal expression of gelatinase A in aqueous humor.

Adult↗

PubMed1999

[Mini-invasive surgery of the retroperitoneal space in children].

UNLABELLED: Although laparoscopic surgery now represents today an essential surgical technique, its use remains limited in urology and especially in pediatric urology for many reasons, main because of the lack of indications. After a large experience acquired in abdominal laparoscopic surgery, and because we were convinced of the advantages offered by this new mini-invasive approach, we have tried to develop it for the retroperitoneal space. METHODS: Over a five-year period we performed 88 retroperitoneal procedures in children:--50 nephrectomies (44 total, 10 partial) for the following indications: 15 polycystic dysplastic kidney, 13 kidney destroyed by reflux, 18 by obstruction, hypertensive uropathy 3, pyonephrosis 1.--5 renal cystectomies, 3 pyelolithotomies, 2 pyeloureteral obstructions, 2 adrenalectomies, 1 retrocaval ureter, 25 varicoceles. The age range was 2 months to 16 years (mean: 3.7 years, 25 children under 1 year). The patients were placed in the lateral debubitus. The retroperitoneal space was created by dissection under direct vision, then insufflation was performed directly in the retroperitoneal space without balloon. Three or four ports were used except for varicocelectomy which was performed with only one port and an operating channel telescope. RESULTS: Follow-up range was 6 months to 5 years. The mean operating time was 96 minutes (35 to 210 min.). Average postoperative stay was 2 days. Conversion was needed in 7 cases (8%). Operative incidents consisted of one duodenal perforation, one ureteral burn, 21 peritoneal perforations (24%). There were 5 postoperative complications (2 urinomas after partial nephrectomy, 1 hydrocele, 1 varicocele recurrence, 1 recurrent stones) not related to the technique. 3 cases needed reoperation (ureteral injury, varicocele recurrence, recurrence of cystine stones) with good result. CONCLUSION: Like other laparoscopic techniques, retroperitoneoscopy requires a training: it remains delicate in children because of the reduced working space and the fragility of the peritoneum. However the advantages seem sufficiently obvious for us to recommend and promote this procedure.

Adolescent↗

PubMed1999

[Benign testicular tumors in children. Value of simple tumorectomy].

From 1984 to 1999, the authors observed 18 intratesticular tumours, 13 of which corresponded to benign lesions. The objective of this study is to define preoperative and intraoperative criteria of benign lesions in order to allow conservative management (simple excision or enucleation) and to analyse the results of this treatment. The 13 boys of this series were between the ages of 5 months and 14 years (mean: 7.1 years). The lesion presented as scrotal swelling in 12 cases and gynaecomastia in 1 case. Tumour markers (alphafoetoprotein, beta HCG) were at the limit of normal for age. Ultrasonography was performed in every case. In each case, treatment consisted of primary exposure of the pediclc with clamping then exteriorization and macroscopic examination of the lesion. Frozen section examination was performed in 11 cases. Treatment consisted of 9 enucleations and 4 orchidectomies. The final histology concluded on epidermoid cyst or simplified teratoma with exclusively ectodermal development in 4 cases, multi-differentiated teratoma in 2 cases, sex cord tumour in 2 cases, simple cyst in 2 cases, rete testis dysplasia in 1 case, cavernous haemangioma in 1 case, and vestigial cyst in 1 case. There was no discordance between the final histological examination and the frozen section examination. The mean follow-up is 4.4 years. No secondary atrophy and no local or distant recurrence was observed in the 9 cases of enucleation. In conclusion, testicular tumours are often benign in children. Selection based on a body of clinical, laboratory, radiological and frozen section histological evidence should allow carcinologically safe conservative surgery with an aesthetic, psychological and functional benefit for the child.

Adolescent↗

PubMed1996

Point mutations characterize KEL10, the KEL3, KEL4, and KEL21 alleles, and the KEL17 and KEL11 alleles.

BACKGROUND: The Kell blood group system is complex, consisting of five sets of alleles and expressing high- and low-incidence antigens and at least 11 other independently expressed antigens. The molecular basis of two sets of alleles: KEL1 (K) and KEL2 (k) and KEL6 (Jsa) and KEL7 (Jsb) have been elucidated as single-base mutations leading to amino acid changes. The molecular basis for the KEL3 (Kpa), KEL4 (Kpb), and KEL21 (Kpc) alleles, the KEL11(Cote) and KEL17(Wka) alleles, and for KEL10 (UIa) is now reported. STUDY DESIGN AND METHODS: Genomic DNA from unrelated individuals with KEL:3,-4,-21 [Kp(a+b-c-)], KEL:-3,-4,21 [Kp(a-b-c+)], KEL:17,-11, and KEL:10 (UIa) phenotypes was amplified by polymerase chain reaction (PCR) with primers for the 19 exons of KEL. The PCR products were sequenced and compared to the DNA sequences of a common Kell system phenotype, KEL:-3,4,-21,-17,-10. Base mutations found were confirmed by restriction fragment length polymorphism analysis in which DNA of unrelated persons with similar red cell phenotypes was used. RESULTS: In all cases, single-base mutations were responsible for the expression of the various antigens. In KEL3 (Kpa), KEL4 (Kpb), and KEL21 (Kpc), point mutations at the same codon in exon 8, encoding amino acid residue 281, distinguish the three genes. KEL4 has the CGG codon for arginine, KEL3 has the TGG codon for tryptophan, and KEL21 has the CAG codon for glutamine. KEL17 has a T1025C mutation in exon 8, encoding a valine-to-alanine amino acid change at residue 302. KEL10 has an A1601T mutation in exon 13, encoding a glutamic acid-to-valine change at residue 494. In all cases, the point mutations created restriction enzyme sites, and PCR-based restriction fragment length polymorphisms confirmed that these point mutations occurred in unrelated persons with the same red cell phenotype. CONCLUSION: Single-base substitutions characterize the KEL3, KEL21, KEL17, and KEL10 genes. The allelic relationship of KEL3, KEL4, and KEL21 was confirmed because the mutations occur in the same codon, expressing different amino acids. PCR-based restriction fragment length polymorphisms can be used to distinguish genotypes.

Alanine↗

PubMed1992

Longitudinal monitoring for disease progression of localized juvenile periodontitis.

The present study was performed to investigate the factors associated with disease progression in localized juvenile periodontitis (LJP) patients by longitudinal monitoring of microbiological changes. Following a 9-month period, 9 LJP patients were divided into 2 groups based upon attachment loss, progressing and non-progressing. Both groups received scaling, root planing, and modified Widman flaps. Clinical and microbiological data were obtained at baseline, following the observation period, and at 6 and 12 months post-treatment. At 6 and 12 months post-treatment significantly more cocci were persistent in the non-progressing group than in the progressing group. Actinobacillus actinomycetemcomitans was also more frequently isolated in the progressing group than in the non-progressing group initially and following the 9-month observation period. Also after treatment, A. actinomycetemcomitans recolonized earlier in the progressing group than in the non-progressing group. These studies suggest that A. actinomycetemcomitans may play a role in disease progression in LJP; however, they do not eliminate the possibility that other organisms may also play a role, since A. actinomycetemcomitans was not detected in all of the patients in whom disease progressed.

Adolescent↗

PubMed1986