Frequency downshift of Nd:YAG lasers and terahertz radiation

The interaction between an intense laser and a cotraveling relativistic dense electron beam could result in the downshifting of the laser frequency. It is theoretically analyzed that this process can generate a coherent terahertz radiation. The radiation energy could reach the order of 1 mJ per shot in the duration of 100 ps, or a temporal radiation power of 10 MW, with a set of practically relevant parameters.

Enhanced expression of heme oxygenase-1 and carbon monoxide excitatory effects in oxytocin and vasopressin neurones during water deprivation

A growing body of evidence indiates that carbon monoxide (CO) acts as a gas neurotransmitter within the central nervous system. Although CO has been shown to affect neurohypophyseal hormone release in response to osmotic stimuli, the precise sources, targets and mechanisms underlying the actions of CO within the magnocellular neurosecretory system remain largely unknown. In the present study, we combined immunohistochemistry and patch-clamp electrophysiology to study the cellular distribution of the CO-synthase enzyme heme oxygenase type 1 (HO-1), as well as the actions of CO on oxytocin (OT) and vasopressin (VP) magnocellular neurosecretory cells (MNCs), in euhydrated (EU) and 48-h water-deprived rats (48WD). Our results show the expression of HO-1 immunoreactivity both in OT and VP neurones, as well as in a small proportion of astrocytes, both in supraoptic (SON) and paraventricular (PVN) nuclei. HO-1 expression, and its colocalisation with OT and VP neurones within the SON and PVN, was significantly enhanced in 48WD rats. Inhibition of HO activity with chromium mesoporphyrin IX chloride (CrMP; 20 μm) resulted in a slight membrane hyperpolarisation in SON neurones from EU rats, without significantly affecting their firing activity. In 48WD rats, on the other hand, CrMP resulted in a more robust membrane hyperpolarisation, significantly decreasing neuronal firing discharge. Taken together, our results indicate that magnocellular SON and PVN neurones express HO-1, and that CO acts as an excitatory gas neurotransmitter in this system. Moreover, we found that the expression and actions of CO were enhanced in water-deprived rats, suggesting that the state-dependent up-regulation of the HO-1/CO signalling pathway contributes to enhance MNCs firing activity during an osmotic challenge.

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.

[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.

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.

[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.

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.

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

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.