The ESCRT-0 subcomplex component Hrs/Hgs is a master regulator of myogenesis via modulation of signaling and degradation pathways

Background

Myogenesis is a highly regulated process ending with the formation of myotubes, the precursors of skeletal muscle fibers. Differentiation of myoblasts into myotubes is controlled by myogenic regulatory factors (MRFs) that act as terminal effectors of signaling cascades involved in the temporal and spatial regulation of muscle development. Such signaling cascades converge and are controlled at the level of intracellular trafficking, but the mechanisms by which myogenesis is regulated by the endosomal machinery and trafficking is largely unexplored. The Endosomal Sorting Complex Required for Transport (ESCRT) machinery composed of four complexes ESCRT-0 to ESCRT-III regulates the biogenesis and trafficking of endosomes as well as the associated signaling and degradation pathways. Here, we investigate its role in regulating myogenesis.

Results

We uncovered a new function of the ESCRT-0 hepatocyte growth factor-regulated tyrosine kinase substrate Hrs/Hgs component in the regulation of myogenesis. Hrs depletion strongly impairs the differentiation of murine and human myoblasts. In the C2C12 murine myogenic cell line, inhibition of differentiation was attributed to impaired MRF in the early steps of differentiation. This alteration is associated with an upregulation of the MEK/ERK signaling pathway and a downregulation of the Akt2 signaling both leading to the inhibition of differentiation. The myogenic repressors FOXO1 as well as GSK3β were also found to be both activated when Hrs was absent. Inhibition of the MEK/ERK pathway or of GSK3β by the U0126 or azakenpaullone compounds respectively significantly restores the impaired differentiation observed in Hrs-depleted cells. In addition, functional autophagy that is required for myogenesis was also found to be strongly inhibited.

Conclusions

We show for the first time that Hrs/Hgs is a master regulator that modulates myogenesis at different levels through the control of trafficking, signaling, and degradation pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01091-4.

[Tardive dyskinesia and second generation antipsychotics: a review of four cases]

We report four cases of tardive dyskinesia (TD) with second generation antipsychotics (SGA). All of those cases where women, three of them had affective psychosis. The presentation of TD where choreo athetosis in one case, respiratory dyskinesia in another and a tardive dystonia in a third. The fourth one had a very precocious form after just a few weeks of treatment. All of them, except one, had a major form of the disorder, with a major impact on their quality of live. We discuss the necessity to remain aware of this dangerous side effect and to keep it in mind while prescribing SGA for bipolar disorders.

Scaling of resistive guiding of laser-driven fast-electron currents in solid targets

The resistive magnetic field plays a crucial role in determining the laser produced fast-electron transport in solid targets. The scaling of the resistive guiding is derived and benchmarked against two-dimensional collisional particle-in-cell simulations. We study the impact of the initial state of the material (Z dependence, conductor, or insulator) on global electron-transport patterns, and conclude that the initial state of a conductor or insulator is not important. Instead, global transport patterns depend on the material Z. The fast-electron transport seen in the simulations is consistent with the derived scaling rule. Previous experimental observations [e.g., R. B. Stephens et al., Phys. Rev. E 69, 066414 (2004) and Y. Sentoku et al., Phys. Rev. Lett. 107, 135005 (2011)] that show confinement or divergence in various regimes are also explained by our scaling. The presented scaling then becomes a useful tool to design compact radiation sources or fast ignitor experiments.

Propagation of a laser-driven relativistic electron beam inside a solid dielectric

Laser probe diagnostics: shadowgraphy, interferometry, and polarimetry were used for a comprehensive characterization of ionization wave dynamics inside a glass target induced by a laser-driven, relativistic electron beam. Experiments were done using the 50-TW Leopard laser at the University of Nevada, Reno. We show that for a laser flux of ∼2 × 10(18) W/cm2 a hemispherical ionization wave propagates at c/3 for 10 ps and has a smooth electron-density distribution. The maximum free-electron density inside the glass target is ∼2 × 10(19) cm-3, which corresponds to an ionization level of ∼0.1%. Magnetic fields and electric fields do not exceed ∼15 kG and ∼1 MV/cm, respectively. The electron temperature has a hot, ringlike structure with a maximum of ∼0.7 eV. The topology of the interference phase shift shows the signature of the "fountain effect", a narrow electron beam that fans out from the propagation axis and heads back to the target surface. Two-dimensional particle-in-cell (PIC) computer simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields driven by laser. The very low ionization observed after the laser heating pulse suggests a fast recombination on the sub-ps time scale.

In Vivo Thrombogenicity of Embolic Protection Systems for Angioplasty and Stenting

Despite the increasing use of embolic protection systems (EPS) for carotid stenting, their intrinsic in vivo thrombogenicity remains unknown. We studied three different types of EPS (n = 24) deployed in the carotid arteries of pigs in which pools of platelets and fibrinogen were labelled with 111In and 125I. The amount of clot deposition seen on photography was also scored using a qualitative scale.

EPS made of fabric nets under normal flow conditions were 5–6 and 15–16 times more thrombogenic (for both platelet (P=.04) and fibrin (P=.007)) than Nitinol mesh nets. Clot deposition on Nitinol mesh nets was more abundant under flow arrest than under normal flow conditions (P=.018).

EPS differ in intrinsic thrombogenicity, a characteristic of the material that could be investigated in pre-clinical studies designed to optimize devices.

Skeletal muscle microbiopsy: a validation study of a minimally invasive technique

The study of the peripheral skeletal muscle function in patients with chronic obstructive pulmonary disease (COPD) is of growing interest, but often requires biopsies, usually with the Bergström technique. The current study was designed to test the validity of a minimally invasive technique: the microbiopsy. In 17 patients with COPD and four normal subjects, two specimens of the vastus lateralis were taken percutaneously under local anaesthesia, one with a 16-gauge needle (microbiopsy) and the other with the Bergström needle. The enzymatic activity of citrate synthase (CS) and phosphofructokinase (PFK), and the myosin heavy chain (MyoHC) composition were measured for both techniques. The subjects reported no pain or much less with the microbiopsy compared with the Bergström biopsy. The microbiopsy sample weight reached 55+/-17 mg. The two techniques showed excellent agreement for CS activity and MyoHC composition. The PFK activity did not differ statistically between the techniques, but the agreement was moderate. The agreement between both biopsy techniques was stable over time. The median (range) fibre number within the microbiopsy specimens was 144 (38-286). In conclusion, the current study shows the feasibility and validity of a minimally invasive muscle biopsy technique that appears more comfortable for subjects, compared with the Bergström technique.

Adaptation of the diaphragm and the vastus lateralis in mild-to-moderate COPD

The chronology of diaphragm and vastus lateralis adaptation in chronic obstructive pulmonary disease (COPD) has not been studied. The hypothesis of this study was that muscle changes would occur earlier in the diaphragm than in the vastus lateralis in COPD, a finding that would suggest that local factors would be more important than systemic factors in determining the muscle phenotypic expression, at least in mild-to-moderate disease. The adaptation of the vastus lateralis and diaphragm muscles was evaluated in patients with mild-to-moderate COPD and in subjects with normal pulmonary function. In both groups, the oxidative potential and the number of lipofuscin inclusions were higher in the diaphragm than in the vastus lateralis. Compared to control, the diaphragm in COPD had a higher oxidative capacity and a higher proportion of type I fibres, with a reciprocal decrease in type IIA fibres, while there was no difference in diaphragmatic cross sectional areas, capillarisation and lipofuscin inclusions. No significant differences were found in the vastus lateralis from both groups. In conclusion, these data indicate that the diaphragm in controls and in chronic obstructive pulmonary disease has a higher oxidative potential than the vastus lateralis, and that muscle adaptation occurs earlier in the diaphragm than in the vastus lateralis in mild-to-moderate chronic obstructive pulmonary disease.

New Devices Designed to Improve the Long-Term Results of Endovascular Treatment of Intracranial Aneurysms. A Proposition for a Randomized Clinical Trial to Assess their Safety and Efficacy

SUMMARY

Endovascular coiling can improve the outcome of patients with ruptured intracranial aneurysms, but angiographic recurrences are frequent compared to surgical clipping. New coils or devices have been introduced to improve long-term results of endovascular treatment but none have been the object of a valid clinical trial. We have proposed a multicentric randomized double-blind study comparing radioactive and standard coil occlusion of aneurysms. The purpose of this article is to review issues that are specific to the design of clinical trials to assess embolic agents that could improve the long-term efficacy of endovascular treatment of intracranial aneurysms. The proposed trial is a randomized, multi-center, prospective, controlled trial comparing the new generation coils to standard platinum coils. Blinding, if at all possible, is preferable to minimize bias, at least for follow-up angiographic studies that should cover a period of 18 months. All patients with an intracranial aneurysm eligible for endovascular treatment would be proposed to participate. The study would enrol approximately 500 patients equally divided between the two groups, recruited within two years, to demonstrate a decrease in the recurrence rate, the primary outcome measure, from 20% to 10%. Secondary outcome measures should assure that complications, initial clinical and angiographic results remain unchanged. Independent data safety and monitoring committees are crucial to the credibility of trials and to ensure scientific rigor and objectivity. The scientific demonstration of an improved long-term efficacy, without significant compromise regarding safety, is mandatory before considering the widespread use of a new embolic device for the endovascular treatment of aneurysms.

[Peripheral muscle dysfunction in chronic obstructive pulmonary disease]

Patients with chronic obstructive pulmonary disease (COPD) often develop systemic complications of their disease. Peripheral muscle dysfunction is one such complication and is characterised by atrophy, weakness, and low oxidative capacity. These muscle changes influence exercise tolerance and quality of life independent of the impairment in lung function. In the following article, the evidence for peripheral muscle dysfunction in patients with COPD and the possible clinical implications of this problem will be discussed. Lastly, the available therapeutic options to improve peripheral muscle function in COPD will be reviewed.

Radionuclide and radiation protection data handbook 2nd edition (2002)

This handbook is a reference source of radionuclide and radiation protection information. Its purpose is to provide users of radionuclides in medicine, research and industry with consolidated and appropriate information and data to handle and transport radioactive substances safely. It is mainly intended for users in low and intermediate activity laboratories. Individual data sheets are provided for a wide range of commonly used radionuclides (144 in total). These radionuclides are classified into five different groups as a function of risk level, represented by colours red, orange, yellow, green and blue, in descending order of risk.

The choose-short effect in rat memory for event duration: the subjective-shortening model

Two predictions derived from the subjective-shortening model were tested in rats. The predictions concerned the temporary occurrence of the choose-short effect with extended training at a given retention interval (RI) and the occurrence of a temporary choose-long effect, when RIs shorter than those used during training were applied. In a first experiment, using a stepwise delay procedure with training 0-s RI sessions interpolated between each series of increasing RIs, results showed: (1) a choose-short effect during the stepwise increase in the delay procedure, (2) a temporary occurrence of the choose-short effect during testing at a given RI and (3) a choose-long effect in half of the animals, when a RI shorter than that used previously was applied. These contrasting results suggest that the disappearance of the choose-short effect could be, as proposed by the model, either the consequence of the foreshortening of the reference memory (for rats choosing-long) or the consequence of an adaptation of the working memory (for rats which did not choose long). Results were discussed in relation with the procedure which could have contributed, by the interposition of 0-s RI sessions, to maintain a stable reference memory. In order to test this interpretation, a second experiment, using the classical stepwise delay procedure without training sessions interpolated, was carried out. In these conditions, rats did never present a significant choose-long effect when the RI was shortened. These results suggest that rats maintained a stable reference memory and could improve their performances during retention testing sessions either by an adaptation of their working memory or by the adoption of an alternative strategy which consisted in learning to maintain an orientation towards the location of the correct lever.

Anatomic landmarks to estimate the length of the diaphragm from chest radiographs: effects of emphysema and lung volume reduction surgery

STUDY OBJECTIVES

To define anatomic landmarks that can be used to predict insertions of the diaphragm on chest radiographs and to estimate diaphragm length.

DESIGN

Prospective clinical trial with a parallel group design.

SETTING

Laboratory investigations in normal volunteers recruited by advertisement and in emphysema outpatients being evaluated for elective bilateral lung volume reduction surgery (LVRS).

PATIENTS

Twenty-six normal subjects classified into young and older age groups, with a third group of 13 emphysema patients matched for age and sex with the older group.

MEASUREMENTS

Identification and between-group comparisons were made of anatomic landmarks on anteroposterior and lateral chest radiographs obtained at total lung capacity. Predicted landmarks were generated from normal subjects. Within-subject and between-group comparisons were made of diaphragm length index (DLI) based on observed anatomic landmarks (DLIobs) and diaphragm length index based on predicted anatomic landmarks (DLIpred) at functional residual capacity.

RESULTS

Anatomic landmarks were not different between the three groups or between male and female subjects, and were not different before and after LVRS in emphysema patients. No difference was found between DLIobs and DLIpred in normal subjects and emphysema patients, but both were smaller in emphysema patients than in normal subjects and increased after LVRS in emphysema patients.

CONCLUSION

This study validates the use of anatomic landmarks to estimate DLI. Using these landmarks simplifies the determination of diaphragmatic lengths and could be a useful tool for the evaluation of the functional capacity of the diaphragm, and possibly as a prognostic indicator of patients who are candidates for LVRS.

Impact of multiple insertions of two retroelements, ZAM and Idefix at an euchromatic locus

Transposable elements represent a large fraction of eukaryotic genomes and they are thought to play an important role in chromatin structure. ZAM and Idefix are two LTR-retrotransposons from Drosophila melanogaster very similar in structure to vertebrate retroviruses. In all the strains where their distribution has been studied, ZAM appears to be present exclusively in the intercalary heterochromatin while Idefix copies are mainly found in the centromeric heterochromatin with very few copies in euchromatin. Their distribution varies in a specific strain called RevI in which the mobilization of ZAM and Idefix is highly induced. In this strain, 15 copies of ZAM and 30 copies of Idefix are found on the chromosomal arms in addition to their usual distribution. Amongst the loci where new copies are detected, a hotspot for their insertion has been detected at the white locus where up to four elements occurred within a 3-kb fragment at the 5' end of this gene. This property of ZAM and Idefix to accumulate at a defined site provides an interesting paradigm to bring insight into the effect exerted by multiple insertions of transposable elements at an euchromatic locus.

The prion protein has RNA binding and chaperoning properties characteristic of nucleocapsid protein NCP7 of HIV-1

Transmissible spongiform encephalopathies are fatal neurodegenerative diseases associated with the accumulation of a protease-resistant form of the prion protein (PrP). Although PrP is conserved in vertebrates, its function remains to be identified. In vitro PrP binds large nucleic acids causing the formation of nucleoprotein complexes resembling human immunodeficiency virus type 1 (HIV-1) nucleocapsid-RNA complexes and in vivo MuLV replication accelerates the scrapie infectious process, suggesting possible interactions between retroviruses and PrP. Retroviruses, including HIV-1 encode a major nucleic acid binding protein (NC protein) found within the virus where 2000 NC protein molecules coat the dimeric genome. NC is required in virus assembly and infection to chaperone RNA dimerization and packaging and in proviral DNA synthesis by reverse transcriptase (RT). In HIV-1, 5'-leader RNA/NC interactions appear to control these viral processes. This prompted us to compare and contrast the interactions of human and ovine PrP and HIV-1 NCp7 with HIV-1 5'-leader RNA. Results show that PrP has properties characteristic of NCp7 with respect to viral RNA dimerization and proviral DNA synthesis by RT. The NC-like properties of huPrP map to the N-terminal region of huPrP. Interestingly, PrP localizes in the membrane and cytoplasm of PrP-expressing cells. These findings suggest that PrP is a multifunctional protein possibly participating in nucleic acid metabolism.

Effects of oxygen on lower limb blood flow and O2 uptake during exercise in COPD

PURPOSE

To quantify the effects of acute oxygen supplementation on lower limb blood flow (QLEG), O2 delivery (QO2LEG), and O2 uptake (VO2LEG) during exercise and to determine whether the metabolic capacity of the lower limb is exhausted at peak exercise during room air breathing in patients with COPD.

METHODS

Oxygen (FIO2 = 0.75) and air were randomly administered to 14 patients with COPD (FEV1: 35 +/- 2% pred, mean +/- SEM) during two symptom-limited incremental cycle exercise tests. Before exercise, a cannula was installed in a radial artery and a thermodilution catheter inserted in the right femoral vein. At each exercise step, five-breath averages of respiratory rate, tidal volume, and ventilation (VE), dyspnea and leg fatigue scores, arterial and venous blood gases, and QLEG were obtained. From these measurements, VO2LEG was calculated.

RESULTS

Peak exercise capacity increased from 46 +/- 3 W in room air to 59 +/- 5 W when supplemental oxygen was used (P < 0.001). QLEG, QO2LEG, and VO2LEG were greater at peak exercise with O2 than with air (P < 0.05). During submaximal exercise, dyspnea score and VE were significantly reduced with O2 (P < 0.05), whereas QLEG, VO2LEG, and leg fatigue were similar under both experimental conditions. The improvement in peak exercise work rate correlated with the increase in peak QO2LEG (r = 0.66, P < 0.01), peak VO2LEG (r = 0.53, P < 0.05), and reduction in dyspnea at iso-exercise intensity (r = 0.56, P < 0.05).

CONCLUSION

The improvement in peak exercise capacity with oxygen supplementation could be explained by the reduction in dyspnea at submaximal exercise and the increases in QO2LEG and VO2LEG, which enabled the exercising muscles to perform more external work. These data indicate that the metabolic capacity of the lower limb muscles was not exhausted at peak exercise during room air breathing in these patients with COPD.

Proportional assist ventilation may improve exercise performance in severe chronic obstructive pulmonary disease

PURPOSE

Exercise tolerance is impaired in chronic obstructive pulmonary disease (COPD), in part because of a reduction in ventilatory capacity and excessive dyspnea experienced. The authors reasoned that proportional assist ventilation (PAV), a ventilator mode in which the level of support varies proportionately with patient effort, could be used during exercise to assist ventilation. The purpose of this study was to evaluate the efficacy of PAV to improve exercise endurance and related physiologic parameters in COPD.

METHODS

In 8 patients (age = 62.8 years mean, +/- 6.9 standard deviation) with severe COPD (forced expiratory volume in 1 second = 0.70 +/- 0.21 L) flow, volume, dyspnea, leg fatigue, arterial blood gases, and gas exchange were measured during constant workrate exercise (37 +/- 18 watts; i.e., 80% previously determined maximum oxygen consumption). Crossover exercise trials were performed in random order: while spontaneously breathing through the experimental circuit without assistance (control trial) and with PAV (using 9.8 +/- 2.1 cm H2O/L and 3.3 +/- 1.0 cm H2O/L/sec of volume assist and flow assist, respectively).

RESULTS

The application of PAV during exercise was well tolerated by each subject. Compared with the control measurement at equivalent time during exercise, PAV improved breathing pattern and arterial blood gases while dyspnea was reduced. Consequently, there was a significant increase in exercise duration with PAV (323 +/- 245 seconds during the control trial compared with 507 +/- 334 seconds with PAV, P = 0.02).

CONCLUSIONS

Proportional assist ventilation can improve performance during constant workrate exercise in severe COPD.

Thoracic dimensions at maximum lung inflation in normal subjects and in patients with obstructive and restrictive lung diseases

OBJECTIVES

To compare the distribution of lung volume at total lung capacity (TLC) among adult men and women known to have normal lung function or chronic obstructive disease or restrictive lung disease (RLD).

DESIGN

Five-year retrospective study.

SETTING

Review of available clinical pulmonary function testing (PFT) reports and chest radiographs.

PATIENTS

Sixty-four patients presenting with normal PFT and chest radiograph findings (normal subjects), 26 patients with severe COPD and increased TLC (COPD group), 29 patients with cystic fibrosis (CF) and increased TLC (CF group), and 19 patients with RLD with a clinical diagnosis of pulmonary fibrosis and a reduced TLC (RLD group).

MEASUREMENTS

Average posteroanterior rib cage diameter (PAave), average lateral rib cage diameter (LAave), and average vertical height of the diaphragm (HDIave) were measured using radiography. Normal prediction equations were generated based on stature, body mass index (BMI), age, and sex as independent variables and then used in between-group comparisons.

RESULTS

PAave correlated positively with BMI and age but not with height, whereas LAave correlated positively with BMI and height but not with age. HDIave correlated positively with height and age but negatively with BMI. PAave and LAave were smaller and HDIave was greater in women than men having the same stature. In the COPD group and in male CF group patients, BMI was low and only HDIave was greater than in sex-, age-, and height-matched normal subjects, but in female CF group patients, only the rib cage diameters were greater than normal. In the RLD group, PAave and HDIave were smaller than predicted and inversely related to each other, but LAave was normal.

CONCLUSION

Variations in maximum lung volume caused by gender, growth, or by lung diseases are nonisotropic and entail substantial changes in chest wall shape.

Platelet-activating factor in infants at risk for necrotizing enterocolitis

BACKGROUND

Platelet-activating factor (PAF) is a heterogeneous phospholipid that has been implicated as participating in a number of perinatal disease processes including necrotizing enterocolitis (NEC).

METHODS

Baseline blood levels of PAF and related lipids (PAF-LL) were measured for 164 infants at risk for NEC from 3 neonatal intensive care units. Serial levels were obtained from the 11 infants in whom NEC developed.

RESULTS

The mean peak PAF-LL in the infants without NEC was 2.03 +/- 1.96 ng/mL. Infants with stage II (n = 6) and III (n = 5) NEC had elevated peak PAF-LL values (mean peak value 13.6 +/- 6.9 ng/mL). No PAF-LL measurements obtained from infants during stage II or III NEC were <2.03 ng/mL. Three infants had PAF-LL elevations before the development of any clinical or radiographic evidence of NEC. PAF-LL level increased as the severity of NEC increased and decreased with its resolution. Setting a PAF-LL level of 10.2 ng/mL as a cutoff for NEC had a positive predictive value of 100%.

CONCLUSIONS

PAF-LL determinations can complement clinical and radiographic studies to diagnose and follow the progression of NEC. PAF-LL may have a role in the evolution of NEC.

Life cycle of an endogenous retrovirus, ZAM, in Drosophila melanogaster

ZAM is an env-containing member of the gypsy family of retrotransposons that represents a possible retrovirus of invertebrates. In this paper, we traced ZAM mobilization to get information about a potential path a retroelement may take to reach the germ line of its host. In situ hybridization on whole-mount tissues and immunocytochemistry analyses with antibodies raised against ZAM Gag and Env proteins have shown that all components necessary to assemble ZAM viral particles, i.e., ZAM full-length RNAs and Gag and Env polypeptides, are coexpressed in a small set of follicle cells surrounding the oocyte. By electron microscopy, we have shown that ZAM viral particles are indeed detected in this somatic lineage of cells, which they leave and enter the closely apposed oocyte. Our data provide evidence that the vesicular traffic and yolk granules in the process of vitellogenesis play an important role in ZAM transfer to the oocyte. Our data support the possibility that vitellogenin transfer to the oocyte may help a retroelement pass to the germ line with no need of its envelope product.

The integration machinery of ZAM, a retroelement from Drosophila melanogaster, acts as a sequence-specific endonuclease

Retroviruses and retrotransposons insert into the host genome with no obvious sequence specificity. We examined the target sites of the retroelement ZAM by sequencing each host-ZAM junction in the genome of Drosophila melanogaster. Our overall data provide compelling evidence that ZAM integration machinery recognizes and leads to ZAM insertion into the sequence 5'-GCGCGCg-3'. This unique property of ZAM will facilitate the development of new tools to study the integration process of retroelements.

Effects of age on short-term memory for time in rats

Working memory (WM) for event duration was investigated in four different age groups of rats (6, 12, 18, and 24 months), using a delayed, symbolic-matching-to-sample procedure. In an initial experiment, all age groups responded as though a long sample duration were a short one when retention intervals (RI) were applied. This effect is called the choose-short effect. In a second experiment, in order to test whether, in compliance with the subjective-shortening model, there would be a "shortening" of the sample duration according to the length of the RI, the psychophysical function relating the probability of choosing the long comparison stimulus to sample duration and the point of subjective equality (PSE) were determined across successive RIs in two age groups (6 and 18 months). A significant shift of the psychophysical function towards a longer duration and a significant increase of the PSE appeared as a function of the RI in 6-month-old, but not in 18-month-old rats. These results support the idea that the choose-short effect is due to a shortening of the event duration in the WM in young animals, whereas there is no evidence that the sample forgetting occurred on a time dimension in older rats.

Physiologic consequences of pneumonectomy. Consequences on the pulmonary function

When pneumonectomy is done in children, there is some speculation that lung growth occurs. In the adult population, volume response is incomplete and attributable to alveolar distention rather than multiplication. Stretch is widely regarded as the initial stimulus for compensatory growth. The authors review data pertaining to the physiology of the various adjustments that occur after pneumonectomy gathered both from observations on human response and from experimental findings in animals. Mechanisms and mediators of this adaptive response are discussed.

Aerobic and strength training in patients with chronic obstructive pulmonary disease

The purpose of this study was to evaluate whether strength training is a useful addition to aerobic training in patients with chronic obstructive pulmonary disease (COPD). Forty-five patients with moderate to severe COPD were randomized to 12 wk of aerobic training alone (AERO) or combined with strength training (AERO + ST). The AERO regimen consisted of three weekly 30-min exercise sessions on a calibrated ergocycle, and the ST regimen included three series of eight to 10 repetitions of four weight lifting exercises. Measurements of peripheral muscle strength, thigh muscle cross-sectional area (MCSA) by computed tomographic scanning, maximal exercise capacity, 6-min walking distance (6MWD), and quality of life with the chronic respiratory questionnaire were obtained at baseline and after training. Thirty-six patients completed the program and constituted the study group. The strength of the quadriceps femoris increased significantly in both groups (p < 0.05), but the improvement was greater in the AERO + ST group (20 +/- 12% versus 8 +/- 10% [mean +/- SD] in the AERO group, p < 0.005). The thigh MCSA and strength of the pectoralis major muscle increased in the AERO + ST group by 8 +/- 13% and 15 +/- 9%, respectively (p < 0.001), but not in the AERO group (3 +/- 6% and 2 +/- 10%, respectively, p > 0.05). These changes were significantly different in the two study groups (p < 0.01). The increase in strength of the latissimus dorsi muscle after training was modest and of similar magnitude for both groups. The changes in peak exercise work rate, 6MWD, and quality of life were comparable in the two groups. In conclusion, the addition of strength training to aerobic training in patients with COPD is associated with significantly greater increases in muscle strength and mass, but does not provide additional improvement in exercise capacity or quality of life.

Delta opiate receptors account for the castration-induced unmasking of gonadotropin-releasing hormone binding sites in the rat pituitary

Under control incubation conditions, gonadotropin-releasing hormone (GnRH) binds only a fraction of its receptors in rat-cultivated pituitary cells. Unmasking of the remaining receptors, which have been termed 'cryptic', requires drug- or peptide-induced protein kinase activation. Spontaneous masking however is not observed on pituitary cells sampled from castrated male rats, suggesting the presence of an intrinsic unmasking factor. Many endogenous factors could theoretically account for the effect. Here we attempted to identify the factor involved by taking advantage of their differential dependency upon second messengers and transduction cascades. Spontaneous unmasking of GnRH binding was found reversed by pertussis toxin (PTX), an inhibitor of alphai and alphao subunits of heterotrimeric G proteins, and by U73122, a phospholipase C (PLC) inhibitor. In contrast, desensitization of protein kinase C (PKC) or inhibition of tyrosine kinase by herbimycin were ineffective. Among endogenous pituitary factors able to unmask GnRH receptors in pituitary cells from normal male rats, as EGF, NPY or opiate peptides, only the latter were found to correspond to this transduction profile. In an attempt to characterize the pharmacology of opiate effects, naloxone (10 microM), a poorly selective opiate antagonist, restored masking of GnRH binding in cells from castrates. Only the delta antagonist naltrindole (1 microM) was able to mimick the action of naloxone. Conversely, when tested on cells from intact animals, morphine (10 microM), as well as dslet (1 microM) and met-ENK (10 nM), preferential delta agonists, but not dago and beta-endorphin or U50488 H and dynorphin, respectively micro and kappa agonists, were able to suppress masking. Among opioid peptides endogenous to the pituitary, only met-ENK was able to unmask cryptic receptors, an effect antagonized by naltrindole. We conclude that an opiate delta receptor subtype is endogenously activated in the pituitary of castrated male rats to prevent masking of GnRH binding.

Anti-CD34+ Fabs generated against hematopoietic stem cells in HIV-derived combinatorial immunoglobulin library suggest antigen-selected autoantibodies

Bone marrow suppression associated with HIV infection does not appear to be solely due to direct viral cytopathic effects. Autoantibodies may play a role in myelosuppression, however it is unclear whether autoantibodies produced in HIV infection represent a primary pathogenic process or merely reflect polyclonal B cell activation. To address these questions, we generated combinatorial immunoglobulin libraries using the pComb3 phagemid from an HIV+ individual with evidence of circulating autoantibodies. From one library, three anti-CD34 Fabs were identified using fresh CD34+ cells as antigenic targets by a method of phage subtraction. The anti-CD34 Fabs are specific by immunoblotting and Elisa and are of high affinity, with calculated Kds in the range of 10(-7) -10(-8) M. Nucleic acid sequencing revealed all three to be of the VH3 family and to have lambda light chains with some gene segments expressing little somatic mutation, while other segments were somatically mutated in patterns suggestive of antigen selection. These findings indicate that (1) A subset of HIV-associated anti-CD34 autoantibodies are monospecific and antigen-selected and are not merely a consequence of polyclonal B cell activation and elevated Ig levels in HIV. Autoreactivity in HIV therefore includes both polyspecific, low affinity antibodies as well as monospecific antigen-selected high affinity antibodies. (2) Although bone marrow suppression in HIV is likely to be multifactorial, autoantibodies to hematopoietic stem cells may contribute to its pathogenesis. (3) Library sampling of VH gene family rearrangements shows no evidence for under-representation of the VH3 family in the immune dysregulation of HIV infection. Phage subtraction is corroborated to be an effective means of identifying, cloning, and characterizing antibodies to hematopoietic differentiation antigens.

Histochemical and morphological characteristics of the vastus lateralis muscle in patients with chronic obstructive pulmonary disease

PURPOSE AND METHODS

In this study, we examined the fiber-type proportions, cross-sectional areas (CSA), and capillarization from needle biopsies of the vastus lateralis muscle in 20 patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 37 +/- 11% predicted, peak VO2 = 13 +/- 4 mL.min-1.kg-1) and nine age-matched normal subjects (peak VO2 = 33 +/- 7 mL.min-1.kg-1). The effects of endurance training on these parameters were also evaluated in 11 of the 20 patients with COPD.

RESULTS

The proportion of Type I fiber was smaller in COPD than normals (34 +/- 14% vs 58 +/- 16 in normals, P < 0.0005) with a corresponding increase in Type IIb fiber (P = 0.015). The CSA of Type I, IIa, and IIab fibers was also smaller in COPD. The capillary to fiber ratio tended to be reduced in patients, but this difference did not reach statistical significance (P = 0.15). The number of capillary contact for Type I, IIa, and IIab fibers was significantly reduced in COPD compared with normal subjects (P < 0.05). When corrected for the CSA, this parameter was similar for both groups. After training, peak VO2 increased by 11% (P < 0.05), the fiber-type proportion remained unchanged, and the CSA of Type I and IIa fibers increased by 31 and 21%, respectively (P < 0.05). Although the number of capillary contact for each fiber types increased with training, the capillary to fiber ratio and the number of capillary contact for the different fiber types relative to their CSA remain unchanged.

CONCLUSIONS

We conclude that in COPD, 1) the vastus lateralis muscle is characterized by a marked decrease in Type I fiber proportion, an increase in Type IIb fiber proportion, a decrease in Type I, IIa, and IIab fiber CSA and by a relatively preserved capillarization; and 2) a 12-wk training program induces a significant increase in Type I and IIa CSA.

Thumb reconstruction by pollicization of an index finger stump combined with a wrap-around flap from the big toe

A finger stump pollicization combined with a thin wrap-around procedure from the big toe for reconstruction of the thumb is described. This technique permits excellent functional and cosmetic restoration, providing length to the new thumb as well as widening the first web. There is joint motion in the reconstructed thumb. Sensibility of the transferred pulp is good and allows fine pinch without pulp shrinkage. This method is indicated in cases of multidigit amputations, for thumb loss near the carpometacarpal joint.

Genomic distribution of the retrovirus-like element ZAM in Drosophila

The mobile element ZAM, recently identified in Drosophila melanogaster, is similar in structure and coding potential to vertebrate retroviruses. In this paper, we analyze the insertional and structural polymorphism of this element and show that members of this family appear to have a long evolutionary history in the genome of Drosophila. It is present in all the species of the D. melanogaster subgroup and in more distantly related species like D. takahashii, D. ananassae, or D. virilis but in a lower copy number or with a lower homology. Two categories of strains have been previously identified in D. melanogaster: strains with a high copy number of ZAM and strains with a low copy number. Here, we show that ZAM is at least in a low copy number in each tested strain of the species analyzed. The study of ZAM's genomic distribution by FISH mapping analysis to salivary gland polytene chromosomes or on mitotic chromosomes indicates that most of the insertion sites of ZAM elements are associated with the constitutive heterochromatin regardless of the ZAM copy number. In addition, our results suggest that multiple ZAM elements are present at the insertion sites visualized by in situ experiments.

Invertebrate retroviruses: ZAM a new candidate in D.melanogaster

ZAM, a new retroelement of Drosophila melanogaster, was identified as a mutational insertion at the white locus. It displays all the structural features of a vertebrate retrovirus. Its three open reading frames encode predicted products resembling the products of the gag, pol and env genes of retroviruses. Its transcription gives rise to an 8.6 kb full-length RNA and a 1.7 kb spliced message for the env gene. The latter encodes an envelope protein that is typical of elements having an extracellular phase of the life cycle. The identification of a ZAM envelope retrogene provides evidence that ZAM is mobilized through a reverse trancriptional process in the germ line of flies. We report that ZAM is distributed differently among D.melanogaster strains. Two stocks out of >15 tested display a ZAM high copy number, with numerous copies distributed on chromosomal arms. This high copy number is associated with a high transcriptional rate of ZAM. The existence of these two categories of strains offers a new genetic system in which the properties of a potential invertebrate retrovirus can be tested.

Cryptic gonadotropin-releasing hormone receptors of rat pituitary cells in culture are unmasked by epidermal growth factor

Protein kinase activators as well as several neuropeptides are able to increase the GnRH-binding capacity of cultured adenohypophyseal cells. To determine whether such up-regulation of GnRH-binding sites can be achieved by a substance(s) endogenous to the pituitary, binding experiments were performed after exposure of cells to increasing amounts of medium conditioned by incubation with primary cultures of adenohypophyseal cells for 4 days. Addition of the conditioned medium elicited a 50% increase in GnRH binding. Characterization of the agent(s) responsible for the effect was attempted by submitting the conditioned medium to molecular sieve filtration, adding or immunoprecipitating endogenous substances, and comparing the susceptibilities of the responses to various inhibitors of transduction processes. Fractionation of the medium indicated that active molecules were of a proteic nature, with M(r) ranging from 5,000-10,000. Among major endogenous moieties corresponding to these criteria [epidermal] growth factor (EGF), transforming growth factor-alpha, and insulin-like growth factors I and II), only the first two exhibited properties similar to those of the conditioned medium. EGF stimulated binding with an EC50 of 3.6 +/- 0.8 pM. Immunoprecipitation of EGF, but not transforming growth factor-alpha, inactivated the conditioned medium. The effects of both conditioned medium and EGF were inhibited by herbimycin, a tyrosine kinase inhibitor; U73122, a phospholipase C inhibitor; and prior desensitization of protein kinase C. In contrast, both were insensitive to pertussis toxin pretreatment. In parallel, EGF did not increase LH secretion by itself, but potentiated its response to GnRH in a concentration range of 1 pM to 1 nM, resulting in a shift of the curve toward lower values of GnRH. It is concluded that EGF is able to control the accessibility of binding sites to GnRH and to potentiate the responsiveness of gonadotropes to the decapeptide.

[Indications and results of breast implant replacement with implants pre-filled with silicone gel]

Based on a series of 74 patients, the authors report their experience of reoperation on unsatisfactory breast implants by the implant replacement technique using silicone prefilled implants. In 92 (57.8%) of the 160 cases, the implant was modified because of a peri-implant capsule, with a satisfactory aesthetic result after only a single operation. However, this leaves the problem of repeated surgical operations, especially in the context of Baker stage IV capsules, which are only partially improved after two to three surgical operations. A particular surgical revision technique is required in the cases, while the role of in situ cortivazol is under investigation. This series comprises two patients with auto-immune disease and dysimmune profiles, not exarcerbate by secondary surgery. Analysis of this series clearly argues in favour of reoperation for unsatisfactory breasts implants. Squeezing manoeuvres appear to be dangerous and useless. Textured implants filled with very cohesive silicone gel should be maintened in view of the absence of any reported serious complications.

[Results of biplane face lifts with maximal skin underlining and vertical SMAS flap]

It is difficult to evaluate the medium and long-term results of facelift due to loss to follow-up of a large number of patients. The authors developed a questionnaire which they sent to their patients. 148 patients (143 women and 5 men) answers this questionnaire and 54 patients returned for review. This subjective evaluation of the results nevertheless had the advantage of identifying three target organs specifically treated by the surgical techniques used: the nasolabial folds, the jowls and the neck. Improvement or deterioration of the results was therefore evaluated and reported on a series of tables. The results are analysed in this paper. 70.3% of patients studied reported a satisfactory objective result with a mean follow-up of 26.8 months. The least favourable results were observed in the neck, due to the small number of technical procedures performed on the platysma, which would appear to justify greater surgical attention. Among the complications reported, 9.2% of cases indicated inadequate results, especially concerning the "lion's wrinkle", which emphasizes the value of a complementary endoscopic procedure at this site. Perioral wrinkles were a source of dissatisfaction in 14.8% of cases, and can be treated by dermabrasion. Lastly, a number of minor complications such as malposition of the ear lobe, facial redness or scar abnormalities were also mentioned and are easily accessible to an ambulatory secondary improvement procedure. This study therefore validated the operative technique of biplane facelift with a satisfactory stability of the results over time. Objective review of dissatisfied patients, who generally returned for review after receiving the questionnaire, led to a number of reoperations, which appear to be useful in the case of early deteriorations occurring during the first postoperative year and which concern about 5% of patients. The ultimate objective of this paper was to try to establish a methodology for the analysis of the long-term results of facelift, without directly involving the examiner or operator, who may ignore what the patient really feels.

A placebo-controlled, crossover comparison of salmeterol and salbutamol in patients with asthma

We compared the effects of salmeterol (Sm) (50 micrograms twice daily) with that of salbutamol (Sb) (200 micrograms four times daily) and placebo (P) in patients with mild-to-moderate asthma with asthma symptoms and related the effectiveness of these therapies between patients who used concurrent inhaled corticosteroids (ICS) and those who did not. The study was a 12-wk, multicenter, double-blind, placebo-controlled crossover trial with 367 adult asthmatics randomized to each trial medication for 4 wk. Inhaled Sb was provided as rescue medication to all patients throughout the trial. Only 80% of patients, albeit the majority, were receiving maintenance treatment with ICS throughout this trial; this reflects practice current in early 1990. Each study day, patients recorded their morning and evening peak expiratory flows (PEF), assessment of asthma symptoms, and use of rescue medication. Both morning and evening PEF were greater during treatment with Sm than with Sb (mean differences between the treatments of 29.8 and 14.3 L/min, respectively) or P (27.7 and 20.3 L/min, respectively) (p < 0.0001). Sm was also more effective than Sb or P in lowering diurnal variation in PEF and increasing the percentage of symptom-free days and rescue-free days and nights with no sleep disturbance (p < or = 0.0004). Sb was more effective than P in increasing evening PEF and the percentage of symptom-free days (p < 0.05) and rescue-free days (p < 0.0001). The same clinical superiority of Sm compared with Sb and P was observed in those patients using ICS (p < 0.001 for all treatment comparisons), and to a greater extent than in those patients not using ICS (i.e., Sm was more effective than Sb and P in just six of the 20 treatment comparisons; p < 0.05). In conclusion, Sm 50 micrograms twice daily is effective in the management of mild-to-moderate asthma and it further improves asthma control in patients already using ICS.

Age-related differences for duration discrimination in rats

The effects of age on duration discrimination were analysed with a symbolic matching-to-sample task, where a compound signal (light and sound) was presented at each trial for a duration of either 2 or 10 s. Four groups of rats (6, 12, 18, and 24 months old) were trained to press one lever if the signal was short and the other if it was long. Results show that, in comparison with younger rats (6 and 12 months), presenescent and senescent rats (18 and 24 months) were slower to reach the acquisition criterion. However, when the performance criterion was met, no age-related difference was found: the percentages of correct responses were equivalent, whatever the duration of the stimulus. These results are in accordance with other data, which have often shown that the cognitive impairment reported in old animals results more from a slowness to learn than from an incapacity to discriminate between different durations.

Rho proteins are localized with different membrane compartments involved in vesicular trafficking in anterior pituitary cells

In order to explore the role of certain GTP binding proteins in the rat anterior pituitary, we have analyzed the subcellular distribution of the proteins rho and rab. They were found in both membrane and cytosolic fractions. Rab1 and rab2 were localized in both Golgi and endoplasmic reticulum (ER) membranes, while rab4 and rab6 were found in fractions enriched with Golgi and plasma membranes, implicating these proteins in the control of vesicular intracellular trafficking as described in other systems. Rab3 was localized like a fraction of synaptophysin, suggesting a role for rab3 in the targeting of "synaptic-like' microvesicles. We have identified three substrates of C. botulinum exoenzyme C3. A 26-kDa substrate with an isoelectric point (pI) of 5.2, probably rhoB, was localized in the lightest fractions such as rab3 and synaptophysin proteins. Two other 23-24 kDa substrates with pI of 5.5-5.8, probably rhoA and/or rhoC, were found in both fractions enriched with ER and secretory granules. Rho proteins have been implicated in the control of actin polymerization. Their localization in anterior pituitary suggests that rhoB could control the association of synaptic-like microvesicles and plasma membrane, and that rhoA/rhoC could play a role in secretory granule exocytosis; these two pathways being involved in cytoskeleton protein reorganisation in response to extracellular signals.

Comparison of Milli-Q PF Plus water to DEPC-treated water in the preparation and analysis of RNA

The Milli-Q PF Plus water-polishing system is equipped with high-purity ion and organic removal media and a capillary fiber ultrafiltration device. The system produces ultrapure water practically free of ribonuclease contamination. The necessity for diethyl pyrocarbonate (DEPC)-treated solutions in RNA molecular biological procedures was tested by preparing RNA from a variety of tissues and tissue-cultured cells using either DEPC-treated, autoclaved solutions or pure Milli-Q PF water dispensed directly from the system. Tissue sources included rabbit brain, heart, lung, liver kidney and bladder as well as cultured human corpus cavernosum smooth muscle cells. RNA was prepared by guanidinium isothiocyanate solubilization, phenol/chloroform extraction and isopropanol precipitation followed by Northern blot analysis. Hybridization with fibronectin (ca. 7.6 kb) and glyceraldehyde-3-phosphate dehydrogenase (1.2 kb) revealed that water from a Milli-Q PF water system performed as well as DEPC-treated, autoclaved solutions. RNA stability at 37 degrees C was examined for various times using rabbit lung RNA in either DEPC-treated water for Milli-Q PF water. Intact RNA was detected after 6 hours in total RNA and by Northern blots hybridized with fibronectin. There was no significant difference in RNA degradation between DEPC-treated water and Milli-Q PF water. We conclude that Milli-Q PF water is an acceptable substitute for DEPC-treated water for the preparation of RNA and Northern blot analysis.