Do retroviruses preferentially integrate within highly plastic regions of the human genome?

Whether retroviral integration is a phenomenon specific to properties of the surrounding genomic region is a widely debated question. In this paper we attempt to enlight the involvement of genomic regions prone to DNA double strand breaks in such process, as well as the more general concept of genome plasticity concerning repair, recombination, transposition events. While performing a differential display analysis of the promonocytic cell line U937 and clone U42 HIV infected counterpart, we found, out of about 15 highly dysregulated genes, expected according to our previous proteomic analysis, two dysregulated cellular transcripts that are shown in the present study to colocalize on band 22q11. The LB14 transcript maps within the DiGeorge critical region. Whereas the AG46 transcript encodes the immunoglobulin-lambda like polypeptide 1 (IGLL1) 4.7Mb apart from LB14. The 22q11 band is remarkable for its high plasticity involving DNA double strand breaks, that may lead to translocations, large deletions, and immunoglobulin rearrangements, frequently observed in this region. We suggest that provirus integration preferentially occurs in such genomic regions and that the subsequent insertional mutagenesis leads to the present observations. Finally, we stress out the possibility that the small size of chromosome 22 is associated with this physical property of the genome.

[Arterial hypertension secondary to curable causes in adults]

EXTENSIVE AND COSTLY INVESTIGATIONS: Are not warranted in the vast majority of hypertensive patients. Characteristics identifying the patients at risk for secondary hypertension can be used to define the small percentage of patients with hypertension who require more extensive diagnostic testing and management of their condition. Exposure to certain medicines, foods or drugs may cause reversible rises in blood pressure. Renovascular and adrenal diseases cause curable forms of hypertension. IN MANY CASES, THE PATIENT'S HISTORY: Examination and simple tests can detect such exposures and disorders. Checking for secondary hypertension is therefore an early step required for the management of all patients with hypertension, provided it is based on clinical signs and inexpensive tests. This primary screening cannot exclude the possibility of renovascular or adrenal disease in a small number of asymptomatic patients. The risk of missing a diagnosis is acceptable provided that blood pressure is normalized by non-specific antihypertensive treatment. However, more extensive etiologic investigation is required in patients who subsequently develop resistant hypertension. This secondary screening requires imaging and biochemical tests that are not required for primary screening. CORRECTION OF THE CAUSES: Of secondary forms of hypertension may restore blood pressure to normal. The patient's age affects the reversibility of renovascular and adrenal hypertension after etiologic treatment: the younger the patient, the higher the probability of blood pressure normalization.

A generalized heterozygote deficiency assessed with microsatellites in French common ash populations

Common ash is a temperate forest tree with a colonizing behaviour, a discontinuous spatial distribution and a peculiar and poorly known mating system. Microsatellite markers were used to study the genetic structure in natural populations of common ash. Twelve populations located in northeastern France were analysed at five loci. Levels of genetic variability within and among stands were estimated for the seedling and adult stages. As expected for a forest tree, our results reveal high levels of intrapopulation diversity and a low genetic differentiation between stands. However, a general and significant heterozygote deficiency was found, with a mean F(IS) of 0.163 for the seedlings and of 0.292 for the adult trees. The different explanations for such an excess homozygosity are discussed: a nonMendelian inheritance of alleles, the presence of null alleles, a Wahlund effect and assortative mating.

AtE2F-a and AtDP-a, members of the E2F family of transcription factors, induce Arabidopsis leaf cells to re-enter S phase

In eukaryotes, transcription factors of the E2F family, in addition to having a role in cell proliferation, participate in regulating apoptosis, differentiation and development. In Arabidopsis thaliana, eight gene sequences have been identified as encoding E2F or DP homologues. DP proteins form heterodimers with E2Fs. The aim of this work was to characterize the functions of three of these factors: AtE2F-a, AtE2F-b and AtDP-a. Here we report that AtE2F-a and AtE2F-b transactivate a reporter gene via an E2F consensus cis-acting element in Arabidopsis protoplasts. AtE2F-a is a more potent activator than AtE2F-b. Furthermore, co-expression of the E2F partner AtDP-a, or the DNA binding protein AtPur alpha, modulates the activation of AtE2F-a. Taken together, these results suggest that AtE2F-a, AtE2F-b and AtDP-a share features characteristic of members of the E2F family of transcription factors. Moreover, over-expression of AtE2F-a and AtDP-a can induce differentiated, non-dividing, leaf cells to re-enter S-phase. We conclude that the transcription factor AtE2F-a plays an important role in progression into S phase, which probably correlates with its capacity to stimulate transcription.

[Management of atherosclerotic renal artery stenoses]

Patients with atherosclerotic renal artery stenosis may develop hypertension, recurrent pulmonary edema and chronic renal failure, but have a much higher risk of dying from stroke or myocardial infarction than of progressing to end-stage renal disease. Indeed, atherosclerotic renal artery stenosis typically occurs in high risk patients with coexistent vascular disease elsewhere. Recent controlled trials comparing medication to revascularization have shown that only a minority of such patients can expect hypertension cure, whereas the results of trials designed to document the ability of revascularization to prevent progressive renal failure are not yet available. Revascularization should be undertaken in patients with atherosclerotic renal artery stenosis and resistant hypertension or heart failure, and probably in those with rapidly deteriorating renal function or with an increase in plasma creatinine levels during angiotensin-converting enzyme inhibition, especially if their renal resistance--index before revascularization is less than 80. With or without revascularization, medical therapy using antihypertensive agents, statins and aspirin is necessary in almost all cases.

[Renal manifestations of sarcoidosis. A report of nine cases]

PURPOSE

Clinical renal outbreaks occurring in the course of sarcoidosis are polymorphous.

METHODS

Nine patients presenting with sarcoidosis were followed up for 18 years.

RESULTS

Five patients presented with chronic interstitial nephritis. Renal failure accompanying granuloma was also present in three of them. Corticotherapy allowed rapid improvement in renal function in three patients. In two other cases, late treatment prevented recovery and led to end-stage renal failure in one case. In another case, persistent hypercalciuria was responsible for bilateral nephrolithiasis further treated via extracorporeal lithotrity. One case of mesangial glomerulonephritis and two morbid associations (retroperitoneal fibrosis and Henoch-Schönlein purpura) were observed.

CONCLUSION

Interstitial nephritis is still a severe clinical renal outbreak. Corticotherapy must be prescribed early to avoid renal failure. Calcium metabolism disorders are frequent and often combined with interstitial nephritis. Hypercalcemia can often and rapidly be improved via corticotherapy, while monitoring of hypercalciuria proves to be more difficult. Membranous glomerulonephritis is still the most frequently reported glomerular lesion.

Efficiency of liposomal ATP in cerebral ischemia: bioavailability features

This study was performed to elucidate the mechanism by which adenosine triphosphate (ATP) encapsulated into liposomes was able to protect against experimental brain ischemia in the rat. After intracarotidal administration of liposomally entrapped ATP, the ATP blood level increased dramatically whereas no change was observed after administration of free ATP. This suggested that liposomes may protect ATP from its degradation by endothelial ectonucleotidases. On the other hand, it was observed that after administration of liposomally entrapped carboxyfluorescein (CF) to ischemic rats, the distribution of the brain fluorescence under the form of numerous punctiform structures was completely different from the diffuse fluorescence obtained with free CF injections. These data suggest that under certain hypoxic conditions the blood-brain barrier is open allowing the liposomes to reach the cerebral parenchyma. The mechanism of brain uptake is, however, still unclear: endothelial tight junctions opening or endothelial transcytosis.

Blockade of dopamine receptors reverses the behavioral effects of endogenous enkephalins in the Nucleus caudatus but not in the Nucleus accumbens: differential involvement of delta and mu opioid receptors

We have previously (Daugé et al. 1988) demonstrated that injection of the mu agonist [D-Ala2, MePhe4, Gly-ol5]-enkephalin (DAGO) or the delta agonist [D-Thr2, Leu5]-enkephalyl-Thr6 (DTLET) into the rat Nucleus accumbens (N.Acc.), or Nucleus caudatus (N.Caud.) induced a hypoactivity followed by hyperactivity 150 min later in the case of the mu agonist and a hyperactivity in the case of the delta agonist. Moreover, naloxone reversible delta-type responses were obtained by local infusion of kelatorphan, ([(R)-3(N-hydroxylcarboxamido-2-benzylpropanoyl)-L-alanine]), a complete inhibitor of enkephalin catabolism, suggesting a tonic control of the behavioral activity of rat by the endogenous opioid peptides. In this work, the putative involvement of the dopaminergic system in these behavioral responses was investigated by using the DA antagonist thioproperazine. In the N.Acc., the behavioral effects of kelatorphan or of mu or delta agonists were not altered by thioproperazine-induced blockade of dopamine receptors. In contrast, the hyperactivity produced by DTLET or by kelatorphan in the N.Caud. was reversed by thioproperazine while the time-dependent biphasic effect resulting from DAGO injection remained unaffected by the DA antagonist. This blocking effect of thioproperazine is in agreement with the previously described delta-selective enhancement of the release of newly synthesized DA in the striatum but not in the N.Acc.

Intracarotidal administration of liposomally-entrapped ATP: improved efficiency against experimental brain ischemia

ATP entrapped into liposomes was administered intracarotidally to rats submitted to brain ischemics episodes by clamping of the carotid arteries and lowering of the systemic blood pressure. It was observed that when entrapped into liposomes, ATP greatly increased the number of ischemic episodes tolerated before brain electrical silence and death appeared. These results added to very similar previous data obtained by i.c.v. treatment excluding the prominent role of cardiovascular effects, could open new possibilities in brain antihypoxic protection. Here and now it cannot be stated if ATP provides direct energetic supply.

Liposomally entrapped adenosine triphosphate. Improved efficiency against experimental brain ischaemia in the rat

Liposomally entrapped adenosine triphosphate (ATP) was administered intracerebroventricularly and intracarotidally to rats subjected to brain ischaemic episodes by clamping of the carotid arteries and lowering of the systemic blood pressure. It was observed that, when entrapped in liposomes, ATP greatly increased the number of ischaemic episodes before brain electrical silence and death. The results open new perspectives in brain ATP supply, which will potentially be useful in human resuscitation from deep brain hypoergic states.