Chromatin folding: from linear chromosomes to the 4D nucleus

The organization of chromatin within the nucleus influences gene expression during cell differentiation and development. Recent work took advantage of the genome-wide localization of molecular marks on chromosomes to analyze their linear distributions at different length scales. Moreover, chromosome conformation capture techniques detect spatial proximity inside the cell nucleus and allow us to characterize local and long-range chromatin loops as well as interchromosomal contacts. These techniques have improved our understanding of chromatin composition in eukaryotic chromosomes, but the principles governing nuclear organization are still little understood. On the one hand, proteins might localize in stable nuclear structures, such as transcription factories, on which chromatin would have to be targeted to be processed. On the other hand, proteins binding to chromatin might induce the formation of specialized nuclear compartments de novo. Current work is aimed at distinguishing between these possibilities and at elaborating predictive models of chromatin folding.

Demonstration of Tokamak ohmic flux saving by transient coaxial helicity injection in the national spherical torus experiment

Transient coaxial helicity injection (CHI) started discharges in the National Spherical Torus Experiment (NSTX) have attained peak currents up to 300 kA and when coupled to induction, it has produced up to 200 kA additional current over inductive-only operation. CHI in NSTX has shown to be energetically quite efficient, producing a plasma current of about 10 A/J of capacitor bank energy. In addition, for the first time, the CHI-produced toroidal current that couples to induction continues to increase with the energy supplied by the CHI power supply at otherwise similar values of the injector flux, indicating the potential for substantial current generation capability by CHI in NSTX and in future toroidal devices.

Microtearing instabilities and electron transport in the NSTX spherical tokamak

We report a successful quantitative account of the experimentally determined electron thermal conductivity chi(e) in a beam-heated H mode plasma by the magnetic fluctuations from microtearing instabilities. The calculated chi(e) based on existing nonlinear theory agrees with the result from transport analysis of the experimental data. Without using any adjustable parameter, the good agreement spans the entire region where there is a steep electron temperature gradient to drive the instability.

Protocol for emergency EPR dosimetry in fingernails

There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail dosimetry, including guidelines for collection and storage of samples, parameters for EPR measurements, and the method of dose assessment. In a blinded test of this protocol application was carried out on nails freshly sampled and irradiated to 4 and 20 Gy; this protocol gave dose estimates with an error of less than 30%.

EPR dosimetry in chemically treated fingernails

By using EPR measurements of radiation-induced radicals it is possible to utilize human fingernails to estimate radiation dose after-the-fact. One of the potentially limiting factors in this approach is the presence of artifacts due to mechanically induced EPR signals (MIS) caused by mechanical stress during the collection and preparation of the samples and the so-called background (non-radiation) signal (BKS). The MIS and BKS have spectral parameters (shape, g-factor and linewidth) that overlap with the radiation-induced signal (RIS) and therefore, if not taken into account properly, could result in a considerable overestimation of the dose. We have investigated the use of different treatments of fingernails with chemical reagents to reduce the MIS and BKS. The most promising chemical treatment (20 min with 0.1 M dithiothreitol aqueous solution) reduced the contribution of MIS and BKS to the total intensity of EPR signal of irradiated fingernails by a factor of 10. This makes it potentially feasible to measure doses as low as 1 Gy almost immediately after irradiation. However, the chemical treatment reduces the intensity of the RIS and modifies dose dependence. This can be compensated by use of an appropriate calibration curve for assessment of dose. On the basis of obtained results it appears feasible to develop a field-deployable protocol that could use EPR measurements of samples of fingernails to assist in the triage of individuals with potential exposure to clinically significant doses of radiation.

Efficient generation of closed magnetic flux surfaces in a large spherical tokamak using coaxial helicity injection

A method of coaxial helicity injection has successfully produced a closed flux current without the use of the central solenoid in the NSTX device, on a size scale closer to a spherical torus reactor, for a proof-of-principle demonstration of this concept. For the first time, a remarkable 60 times current multiplication factor was achieved. Grad-Shafranov plasma equilibrium reconstructions are used to verify the existence of closed flux current. In some discharges the generated current persists for a surprisingly long time approximately 400 ms.

Preclinical safety profile of sildenafil

Sildenafil citrate, marketed as Viagra, for the treatment of erectile dysfunction, has a proven record of safety in humans as predicted by the results of extensive pharmacological and toxicological testing in animals and in vitro, and confirmed by pharmacokinetic exposure data. The aim of this paper is to review succinctly the main findings resulting from these experiments. Daily doses of sildenafil, within and far beyond the human therapeutic range, were given to dogs and rodents for up to 1 and 2 y, respectively. Plasma analyses were conducted to determine the exposure to sildenafil. We found species-specific effects in dogs (Beagle pain syndrome), mice (marked intestinal dilatation) and rats (adaptive reversible hepatocellular hypertrophy associated with secondary thyroid hypertrophy). All these effects in rodents and dogs have no relevance to humans. Morphometric thickness measurements of the retinal layers carried out in response to clinical observations of visual disturbances in humans indicated no difference between treated and control rats and dogs after up to 24 months of treatment. There was no evidence of histopathologic damage to any structures of the visual pathway. Sildenafil had no effects on fertility, no teratogenic potential, was not genotoxic and has no carcinogenic potential. In rats and dogs, safety ratios were 40:1 and 28:1, respectively, in terms of exposure over 24 h (AUC24 h) and 19:1 and 8:1, respectively, in terms of peak plasma concentration (Cmax). These safety ratios illustrate the separation between exposure to sildenafil of animals at large nontoxic doses and the much smaller human therapeutic exposure. This profile highlights the very low risk of human toxicity for sildenafil. The favourable results of the nonclinical safety evaluation of sildenafil in established animal models have been confirmed by many years of clinical experience during the development and marketing of sildenafil.

Long term follow-up of intravesical Bacillus Calmette-Guerin for the treatment of bladder transitional cell carcinoma

OBJECTIVE

To review the long-term follow-up, in terms of recurrence and progression, of transitional cell carcinoma of the bladder treated with intravesical BCG with the following indications: CIS, Ta and T1.

MATERIALS AND METHODS

Ninety-two patients who had received complete course of BCG between 1987 and 1993 were included in the study and followed for an average of 59 months (range 12 to 102).

RESULTS

The recurrence and progression were looked at. Patients treated with BCG for Carcinoma in situ, 11 of 19 (53%) remained tumor-free after 1 or 2 courses of BCG for the duration of the follow-up (mean 4.9 years, range 1.5 to 8.5 years). For patients treated for recurring tumors, 17 of 50 (34%) had no recurrences after 1 or 2 courses of BCG with the same follow-up. When facing multiple tumors, 10 of 23 (43%) patients did not experience recurrences. Therefore, in the 92 patients treated, 38 presented no recurrences after 1 or 2 courses of BCG, for a success rate of 41%. In terms of progression, of the 19 patients treated with BCG for CIS, 4 (21%) went on to develop muscle invasive disease. Of the 50 patients treated for recurrent tumors, 2 (4%) eventually developed lamina propria invasion (initial lesion was a Ta tumor), 4 (8%) carcinoma in situ and 7 (14%) muscle invasive disease, for an overall progression rate of 26% in this group. Of the 25 patients treated for multiple tumors, 1 (4%) developed CIS and 3 (12%) presented with muscle invasive disease, for an overall progression rate of 16% for the duration of the follow-up. Therefore, 21 of 92 (23%) patients had progression of their disease following BCG therapy. No prognostic factors for recurrence or progression could be identified in these tumors.

CONCLUSION

When indications warrant its use, BCG is effective in reducing recurrences and limiting progression in TCC of the bladder. Recurrence within 2 years of treatment is, however, a sign of poor prognosis and other therapeutic options should be sought.

Long-term followup of initial Ta grade 1 transitional cell carcinoma of the bladder

PURPOSE

We evaluate the long-term outcome of initial Ta grade 1 transitional cell carcinoma.

MATERIALS AND METHODS

A total of 152 patients with initial Ta grade 1 bladder tumor were followed for a mean of 76 months (range 6 to 241). Recurrence was defined as positive findings on cystoscopy or biopsy. Progression was defined as an increase in tumor grade or stage.

RESULTS

Tumor recurrence in 83 of 152 patients (55%) was noted within 12 months of followup in 38 patients (46%), between 12 and 24 in 11 (13%), and between 24 and 60 in 22 (27%). A significant number of recurrences (12, 14%) were diagnosed more than 60 months after the first tumor. Of 83 patients with recurrence 31 (37%) had progression, including 21 to grade 2 and 2 to grade 3 disease. Carcinoma in situ was diagnosed in 3 patients and 5 had muscle invasive disease. Progression occurred more than 24 months after initial diagnosis in 20 patients and more than 60 months after first tumor event (2 had carcinoma in situ and 2 had muscle invasive disease) in 12.

CONCLUSIONS

Ta grade 1 bladder transitional cell carcinomas have a high recurrence rate and progression is not uncommon. These findings warrant close long-term followup, even when in some settings the trend is to discontinue followup after 5 years without any abnormal findings.

Binding of drugs to eye melanin is not predictive of ocular toxicity

Ocular melanin is found in the uveal tract and in the pigmented epithelial layer of the retina. Many structurally and pharmacologically unrelated drugs from different therapeutic classes bind to melanin. Examples include numerous drugs acting on the central nervous system, beta-blockers, beta-agonists, antimalarial drugs, sympathomimetic amines, and antibiotics. The critical factors are the acid/base status and the lipophilicity of the molecule. In all cases, there are no direct consequences of drug-melanin binding. Drug-related toxic effects on the retina described in humans and animals are unrelated to melanin binding: melanin binding and retinal toxicity are two separate entities, the latter being related to the intrinsic toxicity of the compound rather than its ability to bind. Chloroquine and phenothiazines are often used as examples of drugs with retinal toxicity linked to melanin binding. In both cases however, experimental data show that the toxic mechanism is unrelated to binding. Melanin binding has also been found to be protective against the ocular toxicity of some drugs. In conclusion, we believe that potential ocular toxicity of future drugs can be assessed adequately by conducting well-designed toxicology studies, and using nonpigmented rodents in addition to pigmented nonrodent species remains fully justified. Binding of drugs to eye melanin is not predictive of ocular toxicity.

Modified Lich-Gregoir ureteral reimplantation: experience of a Canadian center

PURPOSE

Various techniques of ureteral reimplantation have been described for correction of vesicoureteral reflux. We report our experience regarding the safety and efficacy of a modified Lich-Gregoir extravesical approach.

MATERIAL AND METHODS

From January 1991 to January 1996 we evaluated prospectively 256 patients who underwent a modified Lich-Gregoir procedure for correction of vesicoureteral reflux. A total of 385 vesicoureteral units were reimplanted, including 41 duplex systems. The modification to the Lich-Gregoir technique we used consists of ending the paraureteral myotomy with an inverted Y, which permits easier detrusor muscle reapproximation.

RESULTS

This procedure was successful initially in 214 of 237 patients, as confirmed by a normal voiding cystourethrogram 4 to 6 months postoperatively. Of the 237 cases persistent vesicoureteral reflux developed in 13 patients, which resolved spontaneously in 9 after 1 year, contralateral reflux developed in 8, which was treated conservatively, and ureteral obstruction developed in 2. Thus, the 1-year overall success rate was 96%. Urinary retention developed in 12 children with bilateral reimplantation (8.3%) with successful recovery in all after conservative management with urethral catheter drainage of 1 week or less. The duration of hospitalization after surgery ranged from 1 to 3 days.

CONCLUSIONS

The modified Lich-Gregoir technique of extravesical ureteral reimplantation is successful, simple to perform, reproducible and associated with low morbidity. It also requires minimal hospital stay. These results should encourage the use of this technique when indicated to correct vesicoureteral reflux in children.

[Ureteroscopy versus in situ extracorporeal shockwave lithotripsy in the treatment of calculi of the distal ureter]

In a retrospective study from a unique center (St. Luc Hospital, Montreal) stone clearance of 88 consecutive distal ureteral calculi (below pelvic brim) treated by extracorporeal shock wave lithotripsy in situ were compared to a group of 94 distal ureteral calculi treated by ureteroscopy during the same period. Our results show 84% success rate for ureteroscopy which is clearly superior than 58% stone clearance rate at 3 month follow-up for ESWL Success rate was influenced by stone size in the ESWL group but not in the ureteroscopy group. This study reveals similar success rate for calculi smaller than 6 mm but for larger calculi, success rate of ureteroscopy is significantly superior.

The effects of albuterol and isokinetic exercise on the quadriceps muscle group

Subjects performed 9 wk of isokinetic knee extensions twice weekly. Albuterol (N = 13) or placebo (N = 9) was administered for 6 wk; groups received 16 mg.d-1 of either treatment. Training consisted of three sets of 10 repetitions at 45 degrees.s-1. Data were collected at weeks 0, 6, and 9. Concentric and eccentric variables examined included: peak torque (CPT, EPT), total work (CTW, ETW), average power (CAP, EAP), time to peak torque (CTTPT, ETTPT), peak torque to body weight ratio (CPT/BW), and work to body weight ratio (CW/BW, EW/BW). Other variables included: thigh circumference (CIRC), thigh cross-sectional area (CSA), forced vital capacity (FVC), and forced expiratory volume (FEV1), MANOVA and the Dunn-Bonferroni post-hoc found differences within groups for CPT, CTW, CAP, CPR/BW, EPT, ETTPT, and CSA. Interactions were noted for CW/BW, ETW, EAP, EPT/BW, and ETW/BW; with persons administered albuterol yielding superior values. CW/BW, ETW, and EAP showed interactions at post-testing, while EPT/BW and EW/BW interacted at both midtesting and post-testing. Results indicate therapeutic doses of albuterol administered with resistance exercise may augment strength gains.

Characterization of the arteritis induced by infusion of rats with UK-61,260, an inodilator, for 24 h. A comparison with the arteritis induced by fenoldopam mesylate

Administration of fenoldopam mesylate (FM), a dopaminergic agonist, or of cyclic cAMP phosphodiesterase inhibitors (PDE III), for example theophylline and caffeine, induces arteritis in the rat. In this study we characterized the arteritis induced by UK-61,260, an investigational inotropic agent with vasodilatory properties which displays an inhibitory action on cyclic AMP phosphodiesterase, in comparison with lesions induced by FM. The compounds were administered to Sprague-Dawley rats by intravenous infusion over 24 h (FM and UK-61,260), orally or subcutaneously (UK-61,260); the rats were killed and necropsied for pathological examination at various times between 0 h and 28 days post-infusion. Infusion of UK-61,260 at doses of 100, 300 or 400 mg/kg produced arteritis mainly in the mesenteric arteries and occasionally in the renal, pancreatic, gastric and coronary arteries. There were no arterial lesions after infusion of 30 mg/kg, or after administration of 30, 100 or 200 mg/kg per day subcutaneously for 7 days, or after acute administration of 100, 300, 400 or 600 mg/kg orally. Infusion of rats with 72 or 144 mg/kg FM produced arteritis over a wider range of tissues than did UK-61,260. However, the arterial lesions produced by infusion of either drug have the same initial aspect and a similar evolution with time. Immediately after the end of the infusion, minimal necrosis and haemorrhage occurred in the media only, without involvement of the endothelium or the perivascular space. This indicates that the media of the artery is the primary site of injury. The lesions seen 1 and 3 days post-infusion were characterized by severe medial necrosis and haemorrhage with perivascular acute inflammation and appeared macroscopically as haemorrhagic spots on the vessels. On days 7, 14 and 28 post-infusion, no medial necrosis or haemorrhage were present, while perivascular chronic inflammation and moderate smooth muscle hyperplasia were seen. It appeared, therefore, that the lesions underwent repair in 28 days, but footprints of the damage were still present 28 days post-infusion. The similarity between arteritis induced in rats by fenoldopam or by UK-61,260, at doses inducing PDE III inhibition, is consistent with the view that they have a similar pathogenesis. In our view it is probable that these pharmacologically and chemically distinct drugs trigger an increase in intracellular levels of cAMP which in turn triggers vascular damage. The arterial changes observed in the current study after acute administration may explain the increased incidence of polyarteritis nodosa occurring in long term toxicity studies with FM or PDE III inhibitors.

Short-range DNA looping by the Xenopus HMG-box transcription factor, xUBF

Xenopus UBF (xUBF) interacts with DNA by way of multiple HMG-box domains. When xUBF binds to the ribosomal promoter, the carboxyl-terminal acidic tail and amino-terminal HMG-box interact. Binding also leads to negative DNA supercoiling and the formation of a disk-like structure, the enhancesome. Within the enhancesome, an xUBF dimer makes a low-density protein core around which DNA is looped into a single 180-base pair turn, probably by in-phase bending. The enhancesome structure suggests a mechanism for xUBF-dependent recruitment of the TATA box-binding protein complex without direct interaction between the two factors.

Recognition of the Xenopus ribosomal core promoter by the transcription factor xUBF involves multiple HMG box domains and leads to an xUBF interdomain interaction

The interaction of the ribosomal transcription factor xUBF with the RNA polymerase I core promoter of Xenopus laevis has been studied both at the DNA and protein levels. It is shown that a single xUBF-DNA complex forms over the 40S initiation site (+1) and involves at least the DNA sequences between -20 and +60 bp. DNA sequences upstream of +10 and downstream of +18 are each sufficient to direct complex formation independently. HMG box 1 of xUBF independently recognizes the sequences -20 to -1 and +1 to +22 and the addition of the N-terminal dimerization domain to HMG box 1 stabilizes its interaction with these sequences approximately 10-fold. HMG boxes 2/3 interact with the DNA downstream of +22 and can independently position xUBF across the initiation site. The C-terminal segment of xUBF, HMG boxes 4, 5 or the acidic domain, directly or indirectly interact with HMG box 1, making the core promoter sequences between -11 and -15 hypersensitive to DNase. This interaction also requires the DNA sequences between +17 and +32, i.e. the HMG box 2/3 binding site. The data suggest extensive folding of the core promoter within the xUBF complex.

High resolution studies of the Xenopus laevis ribosomal gene promoter in vivo and in vitro

The first high resolution maps of the Xenopus laevis ribosomal promoter and its flanking regions (-179 to +14) have been created by assaying point mutants both in oocyte and in vitro. Within the promoter boundaries (-141(-145) to +3(+4)), domains analogous to the Core Promoter and "Upstream Control Element" (UCE) were clearly detected. The base pairs at -133, within the UCE, and -20, -10, -7, and +3, within the Core, were all shown to be especially important for promotion. Between the Core and UCE, two central promoter elements (CPEs) were also resolved. Surprisingly, these CPEs did not correspond to the highly conserved enhancer homology (approximately -70 to -110), but to CCCGGCC motifs immediately flanking it. Although xUBF was shown to be a limiting component for in vitro transcription, none of the point mutations was found to affect the interaction of this factor with the promoter.

Readthrough enhancement and promoter occlusion on the ribosomal genes of Xenopus laevis

An RNA polymerase I termination site is found just upstream of the ribosomal gene promoter in mammals and amphibia. It has been suggested that this termination site may actively enhance ribosomal transcription in a process known as readthrough enhancement or that it may simply prevent the disruption of initiation complexes or promoter occlusion. There is, however, a consensus of opinion that the terminator is important for efficient ribosomal transcription. Here we have quantitatively investigated the relative importance of readthrough enhancement and promoter occlusion on the transcription of the microinjected Xenopus laevis ribosomal gene. The results show that, in this system, promoter occlusion is limited and terminator mutations predominantly affect readthrough enhancement. The terminator is shown to be unnecessary for the enhancer activity of the rest of the ribosomal spacer. Model calculations suggest that readthrough enhancement could be explained by polymerase recycling and that it may be unnecessary to postulate a specific mechanism of polymerase handover.

Immunocytochemistry of canine thyroid tumors

Immunocytochemical studies using the peroxidase-antiperoxidase method with commercial antibodies against thyroglobulin, calcitonin, calcitonin gene-related peptide (CGRP), neuron specific enolase (NSE), somatostatin, and neurotensin were performed on 38 Bouin-fixed, paraffin-embedded canine thyroid tumors obtained from necropsy and surgical files from 2 Ecoles Nationales Vétérinaires (Alfort and Nantes, France) and from the Laboratoire d'Histo-Cytopathologie Vétérinaire, Maisons-Alfort (France). The tumors consisted of two follicular adenomas, nine follicular carcinomas, nine solid carcinomas, 12 follicular-compact-cellular carcinomas, and six C-cell carcinomas. All 32 follicular-cell tumors were stained positively for thyroglobulin, half of them had weak to moderate positive immunoreactivity for NSE, and all histologic patterns were represented. They had no immunoreactivity for somatostatin or neurotensin. Four C-cell carcinomas had a solid alveolar pattern, while two had a pseudo follicular pattern characterized by uneven, often coalescent, pseudo-follicular formations with a multilayered epithelium surrounding a cavity that often contained red blood cells. Four C-cell carcinomas had uneven immunoreactivity for calcitonin, while all six were positive for CGRP or NSE. Immunoreactivity for CGRP was stronger or more widespread than positivity for calcitonin when both occurred in the same tumor. Some cells of three C-cell carcinomas had positive immunoreactivity for somatostatin. No immunoreactivity for neurotensin was detected. Seven tumors of follicular cell origin contained a few cells positive for calcitonin or CGRP, while three C-cell carcinomas had a few cells positive for thyroglobulin. These tumors were considered to contain entrapped remnants of normal thyroid tissue rather than being dual hormone producing tumors.

Nucleolar organizer regions in cardiac lesions induced by doxorubicin

The use of the argyrophilic (Ag) staining technique for nucleolar organizer regions (NORs) revealed nuclear changes in myocytes of the left atrium of 10 rats treated twice a week for 6 weeks with doxorubicin (1 mg/kg body weight) iv and sacrificed after 6 weeks without treatment. The changes were easily detected qualitatively and further assessed by quantification. Cardiac myocytes of doxorubicin-treated rats had larger nuclei and/or a larger quantity of AgNORs that were either dispersed in a number of small dots or clustered in rounded, rod-shaped, or tortuous large structures. AgNOR alterations may reflect a defect of nucleolar association leading to an impairment of protein synthesis that could be involved in doxorubicin cardiotoxicity.

Immunocytochemistry of thyroid C-cell complexes in dogs

Ten thyroid C-cell complexes from five male and five female Beagle dogs, 1 to 2 years old, were studied using single and double immunocytochemical staining with the peroxidase-antiperoxidase technique. The antigens tested included thyroglobulin, calcitonin, calcitonin gene-related peptide, somatostatin, neuron specific enolase, and neurotensin. All C-cell complexes contained four cell types in various proportions: 1) follicular cells staining for thyroglobulin; 2) C-cells staining for calcitonin, calcitonin gene-related peptide, and neuron specific enolase; 3) stellate cells and cuboidal cells in follicle-like structures staining positively for somatostatin; and 4) undifferentiated cells staining negatively for all antigens. No positive immunoreactivity for neurotensin was detected. These findings support the hypothesis that thyroid C-cell complexes are ultimobranchial remnants that can give rise to thyroid follicles and C-cells.

Pancreatic endocrine responses to nutrients and bombesin after segmental pancreas autotransplantation in dogs

The capacity of autotransplanted (ATP) distal pancreas segments with systemic venous and peritoneal exocrine drainage to support physiologic control of plasma glucose levels was tested, and compared with the functions of "simulated autotransplants" (SATP) prepared with similar dissection and peritoneal exocrine drainage, but with hepatic portal venous drainage, in dogs. In ATP in the postabsorptive state, plasma levels of glucose, immunoreactive insulin (IRI) and immunoreactive glucagon (IRG1) were normal. Autotransplants resulted in impaired glucose tolerance after meals with impaired early insulin responses, and the normal brisk rise of IRG1 in the plasma was delayed and reduced through the first 30 min of feeding. In ATP, also, the response to bombesin was abnormal; the normal stimulation of release of both IRI and IRG1 was delayed in both cases. In studies of responses to oral and intravenous glucose in ATP and SATP dogs, similar mild degrees of glucose intolerance were found with both routes of administration; however, whereas in ATP dogs increases of IRI were highly exaggerated with both routes of administration of glucose, in SATP dogs plasma IRI rose from subnormal levels in the postabsorptive state through subnormal increments with both routes of administration. Further studies are necessary to determine the relative importance of denervation and reduction of the mass of the pancreas in these effects, and to assess the significance of the differences in blood insulin levels in the two preparations.

Histology and histomorphometry of the tibia growth in two turkey strains

Qualitative and quantitative histological methods on decalcified and undecalcified specimens were used for comparing the linear and radial growth of the tibia in two turkey strains: a light strain, Betina, without leg problems and a heavy strain, Maxiboul, with leg problems. Groups of 10 clinically healthy male turkeys of each strain were studied at 2, 6, 8, 16, and 20 weeks of age. Three histomorphometric parameters of longitudinal growth were quantitated in the proximal growth plate and metaphysis. These were: height of the proliferative zone, density of ossification buds (metaphyseal sprouts), and volume of metaphyseal trabecular bone. Four histomorphometric parameters of radial growth were quantitated in the diaphysis. These were cortical thickness, active zone/total surface, density of maturing osteons in the active zone, and bone apposition rate at the maturing primary osteons level. The results showed some evidence for factors predisposing to leg problems in the Maxiboul strain. At 8 weeks, the Maxiboul strain had a lower ossification bud density (13.1/mm2 vs. 20.7/mm2; P less than .05) and a lower metaphyseal trabecular bone volume (16.4% vs. 22.0%; P less than .05) when compared to the Betina strain. No difference was detected in the cortical thickness of the diaphysis in the two strains except at 2 weeks of age (799 microns vs. 387 microns; P less than .001), despite the heavier weight of the Maxiboul strain.

Eosinophilic fasciitis. Ultrastructural study of an early biopsied case

A 55-year-old women with eosinophilic fasciitis was biopsied 8 weeks after the onset of her illness. Under the electron microscope the changes were almost exclusively located in the fascia with many active fibroblasts, accumulation of protocollagen fibrils (10-50 A diameter), elastic fibre remodelling and numerous degranulating mast cells. The inflammatory infiltrate was dense and mostly composed of lymphocytes and plasma cells, with 16% eosinophils. The connective tissue changes may be part of a healing process following microinjury of the fascia. However, large numbers of lymphocytes and plasma cells are unusual in the healing process and are more common in the cellular reaction of morphea. Nevertheless, the absence of macrophages in subcutaneous fat, together with large number of eosinophils in the fascia may be considered to be distinctive features of eosinophilic fasciitis.

[Sciatica caused by disk herniation in children. Apropos of 4 cases]

The authors report 4 cases of sciatica from disk herniation occurring in children under 16. It happens rarely in this age range, as is shown in the review of the literature performed for this article. The symptomatology is similar to that in adults. The physical signs are much more prominent than the functional signs. An original traumatism, sometimes severe, is often encountered. The standard X-ray examination is of little use in diagnosis, while contrast studies (opaque myelography, phlebography) clearly show the lesions of compression. Surgical treatment is frequent but not compulsory, following the same rules than in the adults. The post-operative results are usually excellent.

Déformations du profil du coefficient d'absorption de la raie 5915 A UI dans un générateur de vapeur à cathode creuse pulsée

During the development and study of a hollow cathode pulsed source of uranium vapor, we have observed that the absorption line shape changes considerably with time. This has been shown to be due to oscillatory collective displacement of the vapor in the cavity of the source.

Générateur de vapeur d'uranium: la lampe à cathode creuse pulsée

The production of uranium vapors has been studied in the (5)L(0)(6)ground state using a pulsed hollow cathode lamp. The evolution of the (238)U ((5)L(0)(6)) concentration with time has been studied with Xe and Ar as buffer gases. A density of 2.7 x 10(13) atoms cm(-3) was obtained with Xe as a buffer gas. In addition, those measurements, obtained from the absorption of a laser beam tuned to the 5758.143 A ((5)L(0)(6)-17,361(7)L(6)) transition, allowed the determination of the transition probability A = 2.1 x 10(5) sec(-1) and of the branching ratio BR = 0.08 for this transition.

Etude par absorption d'un faisceau laser d' une vapeur d' (238)U ((5)L(0)(6)) obtenue à l' aide d'une lampe à cathode creuse

The density of U atoms in the (5)L(0)(6) ground state present in a vapor of this element from a hollow cathode lamp has been measured using laser absorption spectroscopy. The influence of the carrier gases (Ar, Kr, Xe) on the density, the absorption coefficient profiles, and on the ratio of U atoms to the dissipated electrical power has been investigated. It has been found that, in our range of operating conditions, the xenon gas is the most efficient. With xenon, a density of 2.2 x 10(12) cm(-3) ground-state U atoms is obtained when the lamp dissipates 40 W of electrical power.

Production de vapeur d'uranium par pulvérisation cathodique dans une cathode creuse: efficacités relatives des gaz Ne, Ar, Kr et concentration à l'état (5)L(0)(6)

We have investigated the production of uranium vapors in the (5)L(0)(6) ground state using a sputtering technique. We have also compared the performance of the Ne, Ar, Kr gases as carrier agents. We have found that the krypton gas gives a maximum yield with minimum energy. Finally the density of U vapors has been found to be of the order of 10(12) atoms cm(-3.).