Chaotic mixing in effective compressible flows.

We study numerically joint mixing of salt and colloids by chaotic advection and how salt inhomogeneities accelerate or delay colloid mixing by inducing a velocity drift V(dp) between colloids and fluid particles as proposed in recent experiments [J. Deseigne et al., Soft Matter 10, 4795 (2014)]. We demonstrate that because the drift velocity is no longer divergence free, small variations to the total velocity field drastically affect the evolution of colloid variance σ(2) = 〈C(2)〉-〈C〉(2). A consequence is that mixing strongly depends on the mutual coherence between colloid and salt concentration fields, the short time evolution of scalar variance being governed by a new variance production term P = -〈C(2)∇ · V(dp)〉/2 when scalar gradients are not developed yet so that dissipation is weak. Depending on initial conditions, mixing is then delayed or enhanced, and it is possible to find examples for which the two regimes (fast mixing followed by slow mixing) are observed consecutively when the variance source term reverses its sign. This is indeed the case for localized patches modeled as Gaussian concentration profiles.

[Relapsing polychondritis. Apropos of 4 cases]. / La polychondrite chronique atrophiante. A propos de 4 observations.

More than three hundred and fifty cases of this ailment can be counted at the present time, an ailment coming into the wide framework of connective tissue diseases with systemic vasculitis. The auricle chondritis remains the most frequent initial localization and its almost constant throughout development. The nasal chondritis is distinguished by its evolution to the saddle-nose deformity. The tracheo-bronchial localization remains the most severe one because of a risk of stenosis. During an evolution made by bouts, the disease also involves rheumatoid, ocular, audio-vestibular, dermatological and renal symptoms. Though an immunologic mechanism seems to be the origin of the disease, the pathogenesis of polychondritis is still mysterious. The polychondritis treatment is based upon systemic steroids therapy and possibly upon immunosuppressive agents as well. Dapsone, recently brought into the polychondritis treatment have not superseded cortico-steroid therapy.

Complete nucleotide sequence of mouse 18 S rRNA gene: comparison with other available homologs.

We present the complete sequence of mouse 18 S rRNA. As indicated by comparison with yeast, Xenopus and rat, the conservation of eukaryotic 18 S rRNA sequences is extensive. However, this conservation is far from being uniform along the molecule: most of the base changes and the size differences between species are concentrated at specific locations. Two distinct classes of divergent traces can be detected which differ markedly in their rates of nucleotide substitution during evolution, and should prove valuable in additional comparative analyses, both for eukaryotic taxonomy and for rRNA higher order organization. Mouse and rat 18 S rRNA sequences differ by only 14 point changes over the 1869 nucleotides of the molecule.

[Measurement of the intestinal clearance of alpha 1-antitrypsin and the exchangeable potassium pool in elderly patients treated with anthraquinone glycosides]. / Mesure de la clairance intestinale de l'alpha 1-antitrypsine et du pool potassique échangeable chez des patients âgés, traités par des glucosides anthraquinoniques.

In order to check the long-term tolerance of a laxative treatment, the authors supervised during six months a group of 14 elderly people (12 women and 2 men) with a mean age of 81.3 years suffering from long-standing constipation without any organic cause. The laxative was given in a daily dosage corresponding to 20 mg of sennosides. Alpha 1-antitrypsin (alpha 1-AT) clearance and exchangeable potassium pool (PPE) were measured, at the beginning (T0), and at the end of the third (T3) and the sixth (T6) months of the study. No abnormal variation of intestinal protein loss (alpha 1-AT: T0, 6.74 +/- 3.16; T3, 2.96 +/- 1.35; T6, 4.15 +/- 1.45 ml/24 h; T0-T3; p less than 0.05, T0-T6, T3-T6: NS) and exchangeable potassium pool (PPE: T0, 19.54 +/- 2.55; T3, 20.29 +/- 3.46, T6, 23.56 +/- 4.92 mEq/kg; T0-T3, T0-T6, T3-T6: NS) was observed. In opposition to current views, all long-term laxative treatments do not necessarily induce significant intestinal protein and potassium losses.

Primary sequence of the 5'-terminal region of mouse 18 S rRNA and adjacent spacer. Implications for rRNA processing.

Among the stepwise cleavage reactions involved in the processing of rRNA precursors in mammalian cells, an early event corresponds to the removal of the so-called 'external transcribed regions' which are located upstream 18 S rRNA sequence within the primary transcript. We have determined the primary sequence of the domain of mouse pre-rRNA which encompasses this early processing site and analyzed its structural features with reference to the other eukaryotic homologs available. The potential involvement of secondary structure features of rRNA precursors in the recognition process for cleavage is discussed.

Recognition signals for mouse pre-rRNA processing. A potential role for U3 nucleolar RNA.

In order to identify signals for rRNA processing in eukaryotes, mouse pre-rRNA sequence features around four cleavage sites have been analyzed. No consensus sequence can be recognized when the four boundary regions are examined. Unlike mature rRNA termini, distal sequences of precursor-specific domains cannot participate in stable duplex with adjacent regions. The extensive divergence of precursor-specific sequences during evolution also applies to nucleotides adjacent to cleavage sites, with a significant exception for a conserved segment immediately downstream 5.8S rRNA. A specific role is proposed for U3 nucleolar RNA in the conversion of 32S pre-rRNA into mature 28S rRNA, through base-pairing with precursor-specific sequences at the boundaries of excised domains.

Structure of mouse rRNA precursors. Complete sequence and potential folding of the spacer regions between 18S and 28S rRNA.

We have determined the complete nucleotide sequence of the regions of mouse ribosomal RNA transcription unit which separate mature rRNA genes. These internal transcribed spacers (ITS) are excised from rRNA precursor during ribosome biosynthesis. ITS 1, between 18S and 5.8S rRNA genes, is 999 nucleotides long. ITS 2, between 5.8S and 28S rRNA genes, is 1089 nucleotides long. Both spacers are very rich in G + C, 70 and 74% respectively. Mouse sequences have been compared with the other available eukaryotes: while no homology is apparent with yeast or xenopus, mouse and rat ITS sequences have been largely conserved, with homologous segments interspersed with highly divergent tracts. Homology with rat is much more extensive for ITS 1 than for ITS 2. Tentative secondary structure models are proposed for the folding of these regions within rRNA precursor; they are closely related in mouse and rat.

[Medium-stay for geriatric patients: a long-stay waiting room or an active rehabilitation unit?]. / Le moyen séjour gériatrique: antichambre du long séjour ou unité active de réadaptation.

From May 1979 to April 1980, 223 patients were discharged from a "medium stay" unit (mean length of stay: 45 days) for geriatric patients in Bordeaux (France). The outcome at discharge was established from retrospective data, and the long-term outcome (18 months) through a letter sent to general practitioners (rate of response: 88,5% with, in some instances, a prompting phone-call). The mortality rates were 22,5% in hospitalized patients and 38% in survivors after discharge. When those hospitalized for social reasons only are excluded, 62,9% of the remaining patients returned to their former place of residence at discharge. Moreover, 83% were still living at the same place after 18 months (range: 12-24 months). Considering the patients' ages and the seriousness of their conditions, "medium stay", geriatric units seem efficient in helping to maintain the aged at home.

Sequence and secondary structure of mouse 28S rRNA 5'terminal domain. Organisation of the 5.8S-28S rRNA complex.

We present the sequence of the 5' terminal 585 nucleotides of mouse 28S rRNA as inferred from the DNA sequence of a cloned gene fragment. The comparison of mouse 28S rRNA sequence with its yeast homolog, the only known complete sequence of eukaryotic nucleus-encoded large rRNA (see ref. 1, 2) reveals the strong conservation of two large stretches which are interspersed with completely divergent sequences. These two blocks of homology span the two segments which have been recently proposed to participate directly in the 5.8S-large rRNA complex in yeast (see ref. 1) through base-pairing with both termini of 5.8S rRNA. The validity of the proposed structural model for 5.8S-28S rRNA complex in eukaryotes is strongly supported by comparative analysis of mouse and yeast sequences: despite a number of mutations in 28S and 5.8S rRNA sequences in interacting regions, the secondary structure that can be proposed for mouse complex is perfectly identical with yeast's, with all the 41 base-pairings between the two molecules maintained through 11 pairs of compensatory base changes. The other regions of the mouse 28S rRNA 5'terminal domain, which have extensively diverged in primary sequence, can nevertheless be folded in a secondary structure pattern highly reminiscent of their yeast' homolog. A minor revision is proposed for mouse 5.8S rRNA sequence.

Unusual processing of nucleolar RNA synthesized during a heat shock in CHO cells.

Maturation of pre-rRNA has been investigated through heat shock experiments in which pre-rRNA synthesis is successively turned off and turned on. After one hour at 43 degrees C high molecular weight RNA is no longer synthesized and both the methylation and the maturation of pre-rRNA synthesized before heat shock are blocked. After two hours recovery at 37 degrees C, methylation and simultaneous maturation of pre-existing RNA occur while pre-rRNA synthesis is reinitiated only after 7 hours at 37 degrees C. During the first 30 min. at 43 degrees C, a residual synthesis of high molecular weight RNA is observed in the nucleolus with an average molecular weight slightly higher than pre-rRNA (4.6 10(6)). During the recovery period at 37 degrees C, RNA synthesized at 43 degrees C is slowly processed into unusual species (39S, 35S, 29S). No new ribosomal RNA appeared in the cytoplasm. This unusual maturation pathway could be a minor pathway of nucleolar RNA processing in exponentially growing cells.

Filterability and cerebro-vascular disease.

800 mg of pentoxifylline 400 was administered daily to two groups of elderly patients (average age 80 years) with the aim of increasing cerebral efficiency. Fifty patients (Group I) were treated for 30 days and of these, 25 patients (Group II) were treated for a further, 60 days. The programme included a battery of psychometric tests (Rey's R.P.M. Recit of Barbizet, coupled image tests, immediate memory test) two geriatric scales (Geriatric Rating Scale and Nosie 30) and study of the deformability of red cells. Results at the 30th and 90th day were compared with pre-experimental results: corrected filterability was increased (Group I and II, P less than 0.05), memory tests showed significant improvement (Group I and II, P less than 0.005), geriatric rating scale showed no modification. There was no correlation between changes in corrected filterability and improvement in psychometric tests.

Acute myeloblastic leukemia in elderly patients: treatment and prognostic factors.

The results of treatment of acute myeloblastic leukemia in patients over 60 years of age are evaluated in a retrospective study of 29 previously untreated patients. These results were very similar to those observed for younger patients, with 18 complete remissions (62, 1%), 6 early deaths, and 5 treatment failures. The median survival time was seven and one half months for all patients and 22 for the 18 patients achieving complete remissions. Nineteen patients received chemotherapy identical to that of younger patients (daunorubicin and cytarabine). The initial presence of poor prognostic factors (hyperleukocytosis, and infection) may explain the relativity high number of early deaths (21%). Elderly patients are apparently not exposed to a higher risk of death than younger patients. Daunorubicin toxicity does not appear to increase with age and this agent may therefore be used in the treatment of older patients.