Cell shape regulates subcellular organelle location to control early Ca2+ signal dynamics in vascular smooth muscle cells.

The shape of the cell is connected to its function; however, we do not fully understand underlying mechanisms by which global shape regulates a cell's functional capabilities. Using theory, experiments and simulation, we investigated how physiologically relevant cell shape changes affect subcellular organization, and consequently intracellular signaling, to control information flow needed for phenotypic function. Vascular smooth muscle cells going from a proliferative and motile circular shape to a contractile fusiform shape show changes in the location of the sarcoplasmic reticulum, inter-organelle distances, and differential distribution of receptors in the plasma membrane. These factors together lead to the modulation of signals transduced by the M3 muscarinic receptor/Gq/PLCß pathway at the plasma membrane, amplifying Ca2+ dynamics in the cytoplasm, and the nucleus resulting in phenotypic changes, as determined by increased activity of myosin light chain kinase in the cytoplasm and enhanced nuclear localization of the transcription factor NFAT. Taken together, our observations show a systems level phenomenon whereby global cell shape affects subcellular organization to modulate signaling that enables phenotypic changes.

Occurrence of nocturia is not mediated by nocturnal hypoxia length and severity in patients with sleep-disordered breathing.

BACKGROUND: Nocturia is highly prevalent in subjects with respiratory sleep disturbances (ie obstructive sleep apnea). The aim of our study is to evaluate whether nocturia is associated with intermittent desaturations or hypoxia length and severity in people undergoing polysomnography. METHODS: We recruited 275 consecutive subjects attending the outpatient clinic for respiratory diseases at Campus Bio-Medico Teaching Hospital. Nocturia was defined as a self-reported voiding frequency ≥ two per night. The groups with and without nocturia were compared with parametric and non-parametric tests, as appropriated. Multivariable logistic regression analysis was used to assess the association of nocturia with patients' characteristics, including oxygen desaturation index (ODI), respiratory efforts (RE) and oxygen saturation below 90% (TST90). RESULTS: Sixty-six (24%) subjects reported nocturia, the median ODI was 15 (8-31), the median RE was 22 (12-38) and the median TST90 was 4.7 (0.3-20.6). ODI and RE were significantly higher in subjects with nocturia as compared with controls. In the multivariable model, ODI was associated with an increased probability of nocturia (OR = 1.03; 95% CI = 1.01-1.06), and the higher the ODI score, the higher the probability to have nocturia (P for trend = 0.038). No significant association was found between TST90 and the occurrence of nocturia. CONCLUSIONS: Intermittent desaturations and not hypoxia length and severity, expressed by TST90, are associated with the occurrence of nocturia in subjects complaining sleep disturbances.

Endoscopic treatment of primary benign central airway tumors: Results from a large consecutive case series and decision making flow chart to address bronchoscopic excision.

BACKGROUND: Benign tracheo-bronchial neoplasms are rare, but potentially dangerous conditions with life threatening consequences. Tumor removal should be pursued by methods minimizing the procedural stress. The role of endoscopic treatment, as an alternative to open surgery, remains controversial. OBJECTIVES: report the twelve-years endoscopic experience in Rome, Italy. Fifty-seven benign tracheo-bronchial tumors were diagnosed and 130 tracheo-bronchial resections by rigid bronchoscopy performed. METHODS: we identified histotypes associated with higher recurrence rate and assessed their relationship with gender, age and tracheo-bronchial location. We provided data on safety and complications and suggested a decision making flow chart to address the patients to endoscopic resection. RESULTS: complete eradication after a single procedure without recurrence at 2 years was obtained in 63.1% of cases (36/57). Need of a second intervention within few months but no further recurrence at follow up was seen in a further 8.8% (5/57). Histotypes associated with recurrence were papillomas and inflammatory polyp. Seven patients (12.3%) were addressed to surgery because of multiple recurrence. Ten patients (17.5%) were lost at follow up. In case of recurrence, the bronchial biopsy was always repeated and no malignant transformation was observed. No major complications, pneumothorax or pneumomediastinum occurred. CONCLUSIONS: endoscopic treatment of benign tracheo bronchial tumors is safe and effective, provided that the procedure is carefully and systematically planned. The rate of eradication is satisfactory and the incidence of complications negligible. This will encourage this approach as first line treatment especially in patients, frequently elderly people, having increased surgical risk due to concomitant respiratory failure or major comorbidities.

The oxygen therapy.

Oxygen (O(2)) is a vital element. Shortage of O(2) results in deranged metabolism and important changes in vascular tone with opposite effects on the systemic and pulmonary circulation. During hypoxemia, oxidative stress exposes the organism to a sort of accelerated senescence as well as to several acute untoward effects. Thus, hypoxemia should be promptly recognized and treated, hopefully by measures tailored to the pathophysiological mechanisms underlying hypoxemia. However, O(2) therapy remains the most common therapy of hypoxemia, but it must be carefully tailored to relieve hypoxemia without provoking hyperoxia or hypercarbia. Then, the individual response to O(2) as well as changing needs of O(2) during sleep or exercise must be evaluated to provide the best O(2) therapy. Hyperoxia, the effect of overcorrection of hypoxia, can dramatically impact the health status and threaten the survival of the newborn and, through different mechanisms and effects, the adult. A thorough knowledge of the pathophysiological bases of hypoxemia and O(2) storage and delivery devices is then mandatory to administer O(2) therapy guaranteeing for optimal correction of hypoxemia and minimizing the risk of hyperoxia. Consistent with this aim also is a careful scrutiny of instruments and procedures for monitoring the individual response to O(2) over time. Thus, at variance from classical pharmacological therapy, performing O(2) therapy requires a vast array of clinical and technical competences. The optimal integration of these competences is needed to optimize O(2) therapy on individual bases.

Sweat testing in addicts under methadone treatment: an Italian experience.

In the last years the interest in monitoring drug exposure with human sweat as alternative biological fluid, is increasing. Sweat collection is convenient, less invasive and difficult to adulterate compared to traditional specimens. The objective of this study was to determine the excretion profile of methadone and other drugs into human sweat. Pharmscope sweat patches (Medical Europe Diagnostic, Madrid, Spain) were used on heroin abusers under methadone treatment. Sweat patches were applied to 10 heroin addicts and 3 drug free volunteers admitted into the study. Sweat patches were worn for about 1 week; urine, saliva and hair samples were collected at the time of the removal of patches. After the extraction, sweat eluates were directly analyzed by GC/MS for the presence of nicotine, cotinine, caffeine, methadone, EDDP and cocaine. The extracts were subsequently derivatized to detect benzoylecgonine, ecgonine methyl ester, morphine, codeine and 6-acetylmorphine. No false positive results were obtained on the drug free samples. All the patches showed positive results for methadone. Cocaine was detected in two cases. Mainly the parent drug was identified rather than the metabolites. The results obtained show the usefulness of sweat as complementary specimen to saliva and urine providing a longer detection window. Moreover, sweat testing offers the advantage of being a non-invasive means of obtaining information about drug exposure.

[A correct nutritional approach as a primary goal in the management of chronic obstructive pulmonary disease]. / Una corretta modulazione nutrizionale come parte integrante del trattamento dei pazienti con BPCO.

The association between weight loss and COPD survival rate is known since the end of 19th century. Several studies showed how an insufficient caloric and nutritional uptake relates with higher mortality in COPD patients. Such clinical evidence brought a deep change in the management of this chronic condition, both in the hospital and home setting. Aim of this brief review is providing an update on the newest scientific evidences supporting the usefulness to systematically provide a complete nutritional evaluation to every COPD patient.

The effect of HIV-1 Gag myristoylation on membrane binding.

During the viral life cycle, an HIV protein, Gag, assembles at the host membrane, specifically at lipid raft regions, at very high concentrations leading to viral particle budding. Gag is post-translationally modified with an N-terminal myristate group which is thought to target Gag to lipid rafts thus aiding in assembly. Here we have analyzed the membrane binding of myristoylated HIV-1 Gag and a non-myristoylated form of HIV-1 Gag to various membrane models. After assessing the extent of myristoylation by HPLC and radiometric assays, we compared membrane binding using fluorescence methods. We found that myristoylated Gag shows a greater than twofold increase in binding affinity to model rafts. A structural model to explain these results is presented.

The effect of hydrostatic pressure on membrane-bound proteins.

Many cellular proteins are bound to the surfaces of membranes and participate in various cell signaling responses. Interactions between this group of proteins are in part controlled by the membrane surface to which the proteins are bound. This review focuses on the effects of pressure on membrane-associated proteins. Initially, the effect of pressure on membrane surfaces and how pressure may perturb the membrane binding of proteins is discussed. Next, the effect of pressure on the activity and lateral association of proteins is considered. We then discuss how pressure can be used to gain insight into these types of proteins.

The effect of hydrostatic pressure on membrane-bound proteins

Many cellular proteins are bound to the surfaces of membranes and participate in various cell signaling responses. Interactions between this group of proteins are in part controlled by the membrane surface to which the proteins are bound. This review focuses on the effects of pressure on membrane-associated proteins. Initially, the effect of pressure on membrane surfaces and how pressure may perturb the membrane binding of proteins is discussed. Next, the effect of pressure on the activity and lateral association of proteins is considered. We then discuss how pressure can be used to gain insight into these types of proteins.

[Multiple cerebral tuberculomas resistant to conventional therapy in an immunocompromised subject]. / Tubercolomi cerebrali multipli resistenti alla terapia convenzionale in un soggetto immunosoppresso.

A 33 years old immunocompromised woman was admitted for a fever of unknown origin during the last five months. She referred a body temperature up to 38.3 degrees C, headache, weakness. The physical examination revealed right homonymous hemianopia, hyperreflexia and Babinski on her right side. A TC scan and a following bioptic specimen showed multiple cerebral tuberculomas. A conventional therapy was started but no significative improvement was observed. She was finally treated with interferon gamma and GM-CSF in addition to the therapy with an important regression of the lesions and significative improvement of the fever and neurological findings.

Role of the gamma subunit prenyl moiety in G protein beta gamma complex interaction with phospholipase Cbeta.

The G protein betagamma complex regulates a wide range of effectors, including the phospholipase Cbeta isozymes (PLCbetas). Prenyl modification of the gamma subunit is necessary for this activity. Evidence presented here supports a direct interaction between the G protein gamma subunit prenyl group and PLCbeta isozymes. A geranylgeranylated peptide corresponding to the C-terminal region of the gamma subunit type, gamma2, strongly inhibits stimulation of PLCbeta2 and PLCbeta3 activity by the betagamma complex. This effect is specific because the same peptide has no effect on stimulation of PLCbeta by an alpha subunit type, alphaq. Prenylation of the gamma peptide is required for its inhibitory effect. When interaction of prenylated gamma subunit peptide to fluorophore-tagged PLCbeta2 was examined by fluorescence spectroscopy, prenylated but not unprenylated peptide increased PLCbeta2 fluorescence emission energy, indicating direct binding of the prenyl moiety to PLCbeta. In addition, fluorescence resonance energy transfer was detected between fluorophore tagged PLCbeta and wild type betagamma complex but not an unprenylated mutant betagamma complex. We conclude that a major function of the gamma subunit prenyl group is to facilitate direct protein-protein interaction between the betagamma complex and an effector, phospholipase Cbeta.

Membrane binding and self-association of alpha-synucleins.

Although its function is unknown, alpha-synuclein is widely distributed in neural tissue and is the major component in the pathological aggregates found in patients with Parkinson's disease, Alzheimer's disease, Down's syndrome, and multiple system atrophy. In this report, we have quantified the binding alpha-synucleins to lipid membranes. In contrast to previous studies, we find, using real time equilibrium fluorescence methods, that alpha-synuclein binds strongly to large, unilamellar vesicles with either anionic or zwitterionic headgroups. Membrane binding is also strong for beta-synuclein, phosphorylated alpha-synuclein, and a synuclein mutant that is associated with familial Parkinson's disease. In solution at less than 400 nM, synuclein has a tendency to undergo concentration-dependent oligomerization as determined by changes in intrinsic fluorescence and fluorescence resonance energy transfer. Above this concentration, the protein begins to aggregate into structures visible by light scattering. Although membrane binding does not affect the secondary structure of alpha-synuclein, it greatly inhibits the ability of this protein to self-associate. Taken together, our results indicate that pathological conditions may be associated with a disruption in synuclein-membrane interactions.

SPME-GC analysis of THC in saliva samples collected with "EPITOPE" device.

In this study we examined the presence of cannabinoids in saliva samples obtained from 24 drug-abusers. The saliva specimens were collected by "EPITOPE" system and the subsequent elution of samples was achieved by centrifugation. The resulting ultrafiltrates have been directly sampled with solid phase micro-extraction (SPME) and then analyzed by GC/MS. Saliva sampling is less invasive than collection of blood.

HIV-1 capsid protein forms spherical (immature-like) and tubular (mature-like) particles in vitro: structure switching by pH-induced conformational changes.

The viral genome and replicative enzymes of the human immunodeficiency virus are encased in a shell consisting of assembled mature capsid protein (CA). The core shell is a stable, effective protective barrier, but is also poised for dissolution on cue to allow transmission of the viral genome into its new host. In this study, static light scattering (SLS) and dynamic light scattering (DLS) were used to examine the entire range of the CA protein response to an environmental cue (pH). The CA protein assembled tubular structures as previously reported but also was capable of assembling spheres, depending on the pH of the protein solution. The switch from formation of one to the other occurred within a very narrow physiological pH range (i.e., pH 7.0 to pH 6.8). Below this range, only dimers were detected. Above this range, the previously described tubular structures were detected. The ability of the CA protein to form a spherical structure that is detectable by DLS but not by electron microscopy indicates that some assemblages are inherently sensitive to perturbation. The dimers in equilibrium with these assemblages exhibited distinct conformations: Dimers in equilibrium with the spherical form exhibited a compact conformation. Dimers in equilibrium with the rod-like form had an extended conformation. Thus, the CA protein possesses the inherent ability to form metastable structures, the morphology of which is regulated by an environmentally-sensitive molecular switch. Such metastable structures may exist as transient intermediates during the assembly and/or disassembly of the virus core.

Role of the major homology region in assembly of HIV-1 Gag.

The major homology region (MHR) is a highly conserved sequence in the gag gene of all retroviruses, including HIV-1. Its role in assembly is unknown, but deletion of the motif significantly impairs membrane binding and viral particle formation. To begin characterizing this defect, we have determined the contribution of this region to the energetics of the assembly process. Intrinsic fluorescence studies were conducted to determine the change in free energy associated with membrane and RNA binding using tRNA and large unilamellar vesicles of 1-palmitoyl-2-oleoylphosphatidylserine as models. For the wild-type protein, the change in free energy was within RT [600 cal/(mol.K)] whether Gag binds first to RNA or to the membrane. Thus, the initial binding of Gag can be to either substrate, but in vivo conditions favor initial association to RNA presumably due to its higher local concentration. After establishing the pattern of assembly, we compared the binding energy of Gag(WT) versus the deletion mutant, Gag(Delta)(MHR). Gag(WT) bound to membranes with a 2-fold higher affinity than Gag(Delta)(MHR), and the binding to RNA was similar for the two proteins. Gag prebound to RNA or to membrane exhibited approximately 2-4-fold greater binding affinity than Gag(Delta)(MHR) for binding the membrane or RNA, respectively. Most importantly, the mutant was significantly impaired in its ability to self-associate on RNA or on membrane surfaces. This key role of the MHR in promoting productive protein-protein interactions was also seen in altered amounts of cleavage products and the lack of membrane-bound, RNA-containing replication intermediates in infected cells. These results suggest that Gag first binds to RNA and then assembles into a multimeric complex with a large membrane-binding face that facilitates subsequent membrane binding. Deletion of the MHR disrupts the protein-protein interactions required to complete this process.