Lab-on-a-brane for spheroid formation

Lab-On-a-Brane (LOB) represents a class of Lab-On-a-Chip (LOC) integrating flexible, highly gas permeable and biocompatible thin membranes (TMs). Here we demonstrate the potentiality of LOBs as cell biochips promoting 3D cell growth. The human cancer cells MCF-7 were cultured into standard multiwells (MWs) and into polydimethylsiloxane (PDMS) MWs, LOCs, and LOBs of different wettability. Surface treatments based on oxygen plasma and coating deposition have been performed to produce hydrophilic, hydrophobic, and oleophobic chips. By a comparison between all these chips, we observed that 3D cell aggregation is favored in LOBs, independent of substrate wettability. This may be attributed to the TM flexibility and the high oxygen/carbon dioxide permeability. Ultimately, LOBs seem to combine the advantages of LOCs as multi-well microfluidic chips to reduce operation time for cell seeding and medium refresh, with the mechanical/morphological properties of PDMS TMs. This is convenient in the perspective of applying mechanical stimuli and monitoring cell stiffness, or studying the metabolism of molecules permeable to PDMS membrane in response to external stimuli with interesting outcomes in cellular biology.

Antibiotic Sensitivity of Bacillus clausii Strains in Commercial Preparation

Recently has been acknowledged the healthy use of Bacillus and related bacteria as probiotics. A mixture reported to contain four probiotic strains of Bacillus clausii is marketed as an OTC (Over The Counter) medicinal supplement for human use. Their poliantibiotic resistant property, useful for restoring the gut microbiota during antibiotic treatment, raises the question about the risk of resistance transfer. In order to better assess the risk-benefit ratio it is important to always monitoring the pattern and stability of resistance spectra in these bacteria. In this work, we have extensively redefined the antibiotic susceptibility profile of these four probiotic strains. Resistance phenotype has been determined by screening a large number of antibiotics, including natural products (such as penicillin, vancomycin and erythromycin), and completely synthetic molecules (such as fluoroquinolones). Extensive comparison with a wild type strain belonging to the normal intestinal microbiome was carried out. The molecular basis of some resistances was determined. Observed antibiotic resistances were correlated with previous and new data in safety evaluations of these strains for human use.

The respiratory chains of four strains of the alkaliphilic Bacillus clausii

•

It is important to understand how alkaliphilic prokaryotes thrive at high pH.

•

An interesting issue is their ability to cope with bioenergetics at high pH.

•

We show that four genetically similar strains adopt different biochemical behaviors.

•

Two of the strains show a functional redundancy of the terminal part of the respiratory chain.

•

Biochemical data correlate with the expression of cytochrome c oxidase and quinol oxidase genes (heme-copper types).

A comparative analysis of terminal respiratory enzymes has been performed on four strains of Bacillus clausii used for preparation of a European probiotic. These four strains originated most probably from a common ancestor through early selection of stable clones for industrial propagation. They exhibit a low level of intra-specific diversity and a high degree of genomic conservation, making them an attractive model to study the different bioenergetics behaviors of alkaliphilic bacilli. The analysis of the different bioenergetics responses has been carried out revealing striking differences among the strains. Two out of the four strains have shown a functional redundancy of the terminal part of the respiratory chain. The biochemical data correlate with the expression level of the mRNA of cytochrome c oxidase and quinol oxidase genes (heme-copper type). The consequences of these different bioenergetics behaviors are also discussed.

Relationship between plasma antioxidants and thyroid hormones in chronic obstructive pulmonary disease

BACKGROUND

A low-T₃ syndrome is observed in chronic diseases, but its treatment is still debated. Chronic obstructive pulmonary disease (COPD) has not been conclusively studied under this aspect. COPD is a complex condition, which cannot be considered a lung-related disorder, but rather a systemic disease also associated to increased oxidative stress. We evaluated thyroid hormones and antioxidant systems, the lipophilic Coenzyme Q10 (CoQ₁₀) and total antioxidant capacity (TAC) in COPD patients to reveal the presence of a low-T₃ syndrome in COPD and investigate the correlation between thyroid hormones, lung function parameters and antioxidants.

METHODS

We studied: 32 COPD patients and 45 controls, evaluating thyrotropin (TSH), free-triiodotyronine (fT₃), free-tetraiodotyronine (fT₄), CoQ₁₀ (also corrected for cholesterol) and TAC. CoQ₁₀ was assayed by HPLC; TAC by the metmyoglobin-ABTS method and expressed as latency time (LAG) in radical species appearance.

RESULTS

We found significantly lower LAG values, fT₃ and fT₄ levels and significantly higher TSH in COPD patients vs. controls. LAG values significantly correlated with fT₃ concentration. 12 out of 32 patients exhibited fT₃ levels lower than normal range. So we divided COPD patients in 2 groups on the basis of the fT₃ concentration (normal fT₃ COPD and low fT₃ COPD). We observed lower LAG values in normal fT₃-COPD, compared to healthy subjects, with a further significant reduction in low fT₃-COPD patients. Moreover higher TSH concentration was present in normal fT₃-COPD, compared to healthy subjects, with a further significant increase in low fT₃-COPD patients. CoQ₁₀/cholesterol ratio was higher in low fT₃-COPD vs. normal fT₃-COPD, with a nearly significant difference.

CONCLUSIONS

These data seem to indicate an increased oxidative stress in low fT₃-COPD and a role of fT₃ in modulating antioxidant systems. However low fT₃ levels are joined to metabolic indexes of true hypothyroidism, suggesting that elevated CoQ₁₀ expresses a reduced tissue utilization. These data might suggest the need of thyroid replacement therapy in such a condition.

Migrainous infarction: association with vascular risk factors in a male subject

Migraine with aura (MA) is associated with an increased risk of ischemic stroke, especially in young women with vascular risk factors (smoke, contraceptive pill). Patent foramen ovale (PFO) has also been associated with MA. We describe a 41-year-old man, in good health, with MA since 16, familiar history of diabetes, heavy smoker (30 cigarettes/day). Frequency (1-2 attacks/year) and clinical features of migraine have been unchanged since the onset. A few days before our examination he suffered a typical migraine attack. In the following hours, however, the headache became more and more throbbing and the aura symptoms (regressed as usual in 30 min) reappeared and persisted, so he went to an Emergency Department. The CT-scan (without contrast) was normal. The following days he had visual disturbances and spatial disorientation. We found a normal neurological examination and fundus oculi. He referred persisting visual troubles. We prescribed MR + angioMR which confirmed a migrainous infarction and ruled out others pathological conditions. Further tests found out dyslipidemia, hyperhomocysteinemia, impaired glucose tolerance. Transcranial Doppler showed right to left shunting. We also prescribed the screening tests for vasculitis (normal). In our opinion this case highlights the relevance of vascular risk factors in MA complications also in male subjects.

Regulation by the cAMP cascade of oxygen free radical balance in mammalian cells

A study is presented of the effect of the cAMP cascade on oxygen metabolism in mammalian cell cultures. Serum-starvation of the cell cultures resulted in depression of the forward NADH-ubiquinone oxidoreductase activity of complex I, decreased content of glutathione, and enhancement of the cellular level of H2O2. Depressed transcription of cytosolic Cu/Zn-SOD 1, mitochondrial glutathione peroxidase and catalase was also observed. Activation of the cAMP cascade reversed the depression of the activity of complex I and the accumulation of H2O2. The effect of cAMP involved the cAMP-dependent protein kinase.

Relationships between plasma CoQ10 levels and thyroid hormones in chronic obstructive pulmonary disease

In previous works we demonstrated an inverse correlation between plasma Coenzyme Q 10 (CoQ10) and thyroid hormones; in fact, CoQ10 levels in hyperthyroid patients were found among the lowest detected in human diseases. On the contrary, CoQ10 is elevated in hypothyroid subjects, also in subclinical conditions, suggesting the usefulness of this index in assessing metabolic status in thyroid disorders. On the other hand, a low-T3 syndrome, due to reduced peripheral conversion from the prohormone T4, is observed in different chronic diseases: this condition is considered an adaptation mechanism, usually not to be corrected by replacement therapy. In order to perform a metabolic evaluation, we have studied a group of 15 patients, aged 69-82 ys, affected by chronic obstructive pulmonary disease (COPD), comparing respiratory indexes, thyroid hormones and CoQ10 levels (also normalized with cholesterol levels) in patients with low (group A) or normal (group B) free-T3 (FT3) concentrations. We found that CoQ10 levels were significantly higher in patients of group A than in B (0.91+/- 0.03 vs 0.7 +/- 0.04 microg/ml respectively); the same difference was observed when comparing the ratios between CoQ10/cholesterol in the two groups (200.16 +/- 8.96 vs 161.08 +/- 7.03 nmol/mmol respectively). These preliminary data seem to indicate that low T3 levels are accompanied by metabolic indexes of a true hypothyroidism in COPD patients. Whether this datum supports the need to perform a replacement therapy in such a condition requires further studies.

Characterization of plasma membrane respiratory chain and ATPase in the actinomyceteNonomuraeasp. ATCC 39727

We have characterized the respiratory system of the aerobic actinomycete Nonomuraea sp. ATCC 39727. The plasma membrane of the microorganism is shown to contain a protonmotive respiratory chain and H+-ATPase. The respiratory chain is made up of a rotenone-sensitive NADH-quinone oxidoreductase, a four subunits aa3-type cytochrome c oxidase and a bc1 complex. The H+-ATPase is characterized as an F0F1-type on the basis of its sensitivity to specific inhibitors; the enzyme is also inhibited by mM concentrations of Ca2+. The activity of the respiratory chain increases during the exponential growth phase, but is depressed in the stationary phase. The H+-ATPase activity reaches, as the respiratory chain, a maximal activity at the end of the exponential growth phase and then remains constant in the stationary phase.

Structures and interactions of proteins involved in the coupling function of the protonmotive F(o)F(1)-ATP synthase

The mitochondrial F(1)F(o) ATP synthase complex has a key role in cellular energy metabolism. The general architecture of the enzyme is conserved among species and consists of a globular catalytic moiety F(1), protruding out of the inner side of the membrane, a membrane integral proton translocating moiety F(o), and a stalk connecting F(1) to F(o). The X-ray crystallographic analysis of the structure of the bovine mitochondrial F(1) ATPase has provided a structural basis for the binding-change rotary mechanism of the catalytic process in F(1), in which the gamma subunit rotates in the central cavity of the F(1) alpha3/beta3 hexamer. Rotation of gamma and eta subunits in the E. coli enzyme and of, gamma and delta subunits in the mitochondrial enzyme, is driven, during ATP synthesis, by proton motive rotation of an oligomer of c subunits (10-12 copies) within the F(o) base piece. Average analysis of electron microscopy images and cross-linking results have revealed that, in addition to a central stalk, contributed by gamma and delta/eta subunits, there is a second lateral one connecting the peripheries of F(o) and F(1). To gain deeper insight into the mechanism of coupling between proton translocation and catalytic activity (ATP synthesis and hydrolysis), studies have been undertaken on the role of F(1) and F(o) subunits which contribute to the structural and functional connection between the catalytic sector F(1) and the proton translocating moiety F(o). These studies, which employed limited proteolysis, chemical cross-linking and functional analysis of the native and reconstituted F(1)F(o) complex, as well as isolated F(1), have shown that the N-terminus of alpha subunits, located at the top of the F(1) hexamer is essential for energy coupling in the F(1)F(o) complex. The alpha N-terminus domain appears to be connected to F(o) by OSCP (F(o) subunit conferring sensitivity of the complex to oligomycin). In turn, OSCP contacts F(o)I-PVP(b) and d subunits, with which it constitutes a structure surrounding the central gamma and delta rotary shaft. Cross-linking of F(o)I-PVP(b) and gamma subunits causes a dramatic enhancement of downhill proton translocation decoupled from ATP synthesis but is without effect on ATP driven uphill proton transport. This would indicate the existence of different rate-limiting steps in the two directions of proton translocation through F(o). In mitochondria, futile ATP hydrolysis by the F(1)F(o) complex is inhibited by the ATPase inhibitor protein (IF(1)), which reversibly binds at one side of the F(1)F(o) connection. The trans-membrane deltapH component of the respiratory deltap displaces IF(1) from the complex; in particular the matrix pH is the critical factor for IF(1)association and its related inhibitory activity. The 42L-58K segment of the IF(1) has been shown to be the most active segment of the protein; it interacts with the surface of one alpha/beta pairs of F(1), thus inhibiting, with the same pH dependence as the natural IF(1), the conformational interconversions of the catalytic sites involved in ATP hydrolysis. IF(1) has a relevant physiopathological role for the conservation of the cellular ATP pool in ischemic tissues. Under these conditions IF(1), which appears to be over expressed, prevents dissipation of the glycolytic ATP.

Functional domains of the ATPase inhibitor protein from bovine heart mitochondria

A study is presented of the activity and temperature dependence of the ATPase inhibitor protein (IF(1)) from bovine heart mitochondria and of synthetic partial IF(1) peptides. The results show that the IF(1)-(42-58) peptide is the most potent inhibitory domain of IF(1).

The structural and functional connection between the catalytic and proton translocating sectors of the mitochondrial F1F0-ATP synthase

The structural and functional connection between the peripheral catalytic F1 sector and the proton-translocating membrane sector F0 of the mitochondrial ATP synthase is reviewed. The observations examined show that the N-terminus of subunit gamma, the carboxy-terminal and central region of F0I-PVP(b), OSCP, and part of subunit d constitute a continuous structure, the lateral stalk, which connects the peripheries of F1 to F0 and surrounds the central element of the stalk, constituted by subunits gamma and delta. The ATPase inhibitor protein (IF1) binds at one side of the F1F0 connection. The carboxy-terminal segment of IF1 apparently binds to OSCP. The 42L-58K segment of IF1, which is per se the most active domain of the protein, binds at the surface of one of the three alpha/beta pairs of F1, thus preventing the cyclic interconversion of the catalytic sites required for ATP hydrolysis.

F1 and F0 connections in the bovine mitochondrial ATP synthase: the role of the of alpha subunit N-terminus, oligomycin-sensitivity conferring protein (OCSP) and subunit d

We have studied the functional effect of limited proteolysis by trypsin of the constituent subunits in the native and reconstituted F1F0 complex and isolated F1 of the bovine heart mitochondrial ATP synthase (EC 3.6.1.34). Chemical cross-linking of oligomycin-sensitivity conferring protein (OSCP) with other subunits of the ATP synthase and the consequent functional effects were also investigated. The results obtained show that the alpha subunit N-terminus is essential for the correct, functional connection of F1 to F0. The alpha-subunit N-terminus contacts OSCP which, in turn, contacts the F0I-PVP(b) and the F0-d subunits. The N-terminus of subunit alpha, OSCP, a segment of subunit d and the C-terminal and central region of F0I-PVP(b) subunits are peripherally located with respect to subunits gamma and delta which are completely shielded in the F1F0 complex against trypsin digestion. This qualifies the N-terminus of subunit alpha, OSCP, subunit d and F0I-PVP(b) as components of the lateral element of the stalk. These subunits, rather than being confined at one side of the complex which would leave most of the central part of the gamma subunit uncovered, surround the gamma and the delta subunits located in the central stalk.

Disulfide cross-linking of subunits F(1)-gamma and F(0)I-PVP(b) results in asymmetric effects on proton translocation in the mitochondrial ATP synthase

A study is presented on the effect of diamide-induced disulfide cross-linking of F(1)-gamma and F(0)I-PVP(b) subunits on proton translocation in the mitochondrial ATP synthase. The results show that, upon cross-linking of these subunits, whilst proton translocation from the A side to the B F(1) side is markedly accelerated with decoupling of oxidative phosphorylation, proton translocation in the reverse direction, driven by either ATP hydrolysis or a diffusion potential, is unaffected. These observations reveal further peculiarities of the mechanism of energy transfer in the ATP synthase of coupling membranes.

[Vascular complications in intestinal obstructions. The role of computed tomography]

INTRODUCTION

We investigated CT capabilities in showing vascular complications (ischemia, infarction) secondary to intestinal obstruction.

SUBJECTS AND METHODS

32 patients with small bowel obstruction, subdivided in two groups, were examined with CT. The first group consisted of 12 patients with small bowel obstruction complicated by ischemic injury. It was due to loop strangulation in 10 cases and loop distension secondary to colon carcinoma in 2 cases. At surgery the loop strangulation was caused by adhesions in 9 cases and by jejunal hernia in 1 case. Vascular complications were segmentary small bowel infarction in 7 cases, colonic infarction in 2 cases and ischemia, which was resolved after loop debridement, in 3 cases. The second group consisted of 20 patients with intestinal occlusion due to adhesions complicated by a closed loop in 4 cases. All patients were examined with(out) i.v. contrast agent administration. Filling of the intestinal loops by oral contrast agent was never performed.

RESULTS

CT identified the vascular injury secondary to intestinal obstruction in 11/12 patients (91%). In one case it was not possible to diagnose mild ischemia, which was found of surgery. CT findings were: loops distention in all the cases; wall thickening in 11 cases with intramural gas in 8 cases and slight contrast enhancement in 1 case; ascites in 2 cases; mesenteric edema in 9 cases; gas at the mesenteric root in 1 case. In the control group, small bowel obstruction was diagnosed with CT in all cases based on the presence of distended loops up to the occlusion site. Parietal alterations above the lesion were never found.

CONCLUSION

CT is a sensitive tool for diagnosing small bowel obstruction and for assessing the site and cause of obstruction. CT plays a pivotal diagnostic role in vascular complications, giving very important indications for a correct treatment.

Topological and functional relationship of subunits F1-gamma and F0I-PVP(b) in the mitochondrial H+-ATP synthase

Diamide treatment of the F0F1-ATP synthase in "inside out" submitochondrial particles (ESMP) in the absence of a respiratory Delta mu H+ as well as of isolated Fo reconstituted with F1 or F1-gamma subunit results in direct disulfide cross-linking between cysteine 197 in the carboxy-terminal region of the F0I-PVP(b) subunit and cysteine 91 at the carboxyl end of a small alpha-helix of subunit F1-gamma, both located in the stalk. The F0I-PVP(b) and F1-gamma cross-linking cause dramatic enhancement of oligomycin-sensitive decay of Delta mu H+. In ESMP and MgATP particles the cross-linking is accompanied by decoupling of respiratory ATP synthesis. These effects are consistent with the view that F0I-PVP(b) and F1-gamma are components of the stator and rotor of the proposed rotary motor, respectively. The fact that the carboxy-terminal region of F0I-PVP(b) and the short alpha-helix of F1-gamma can form a direct disulfide bridge shows that these two protein domains are, at least in the resting state of the enzyme, in direct contact. In isolated F0, diamide also induces cross-linking of OSCP with another subunit of F0, but this has no significant effect on proton conduction. When ESMP are treated with diamide in the presence of Delta mu H+ generated by respiration, neither cross-linking between F0I-PVP(b) and F1-gamma subunits nor the associated effects on proton conduction and ATP synthesis is observed. Cross-linking is restored in respiring ESMP by Delta mu H+ collapsing agents as well as by DCCD or oligomycin. These observations indicate that the torque generated by Delta mu H+ decay through Fo induces a relative motion and/or a separation of the F0I-PVP(b) subunit and F1-gamma which places the single cysteine residues, present in each of the two subunits, at a distance at which they cannot be engaged in disulfide bridging.

Early virus isolation, early structural antigen detection and DNA amplification by the polymerase chain reaction in polymorphonuclear leukocytes from AIDS patients with human cytomegalovirus viraemia

Fifty AIDS patients were investigated for human cytomegalovirus (HCMV) viraemia when potentially HCMV-related clinical symptoms or syndromes were observed. Nine patients underwent prolonged virologic follow-up, while 41 additional patients were examined only once or sporadically. Concentrated preparations of polymorphonuclear leukocytes (PMNL) from 153 blood samples were obtained for monitoring: (1) early virus isolation in cell cultures 24 h p.i. (viraemia); (2) early structural antigen detection in cytospin preparations (antigenemia); and (3) HCMV DNA in blood (DNAemia) through DNA amplification by the polymerase chain reaction (PCR). Viraemia and antigenemia were quantitated, whereas evaluation of DNAemia was only qualitative. A good correlation between levels of viraemia and antigenemia was consistently found except during ganciclovir treatment. HCMV-related clinical symptoms were observed when the number of infected PMNL was greater than 100 per 2 x 10(5) cells examined. All 56 blood samples positive for viraemia and antigenemia were also PCR-positive, whereas 44 samples (39 of which taken from patients with ascertained HCMV infection in blood) were positive by PCR only. Viraemia and antigenemia were often unrelated to HCMV organ syndromes, such as retinitis, in which only DNAemia was often detected. Prolonged ganciclovir treatment kept viraemia, antigenemia and even DNAemia at a low or negative level, yet drug discontinuation led to rapid progression of HCMV infection in blood. In addition, prolonged antiviral treatment could induce appearance of ganciclovir-resistant HCMV strains, requiring alternative foscarnet therapy. In conclusion, determination of viraemia and antigenemia appears essential for correct clinical management and antiviral treatment of disseminated HCMV infections in AIDS patients. However, PCR is the most sensitive method for diagnosis and monitoring of HCMV infections in blood at a pre-clinical stage.