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Guanidinium chloride induced unfolding of a hemocyanin subunit from Carcinus Aestuarii. II) Holo form
No full textPotential role of magnetic resonance brain relaxometry in veterinary medicine: A preliminary study
Full text linkMagnetic Resonance (MR) is a non-invasive modality of choice for the evaluation of brain morphology, with superior performance as compared to other techniques. However, MR images are typically assessed qualitatively, thus relying on the experience of the involved radiologist. This may lead to errors of interpretation in the presence of subtle alterations and does not exploit the full potential of this technique as a quantitative diagnostic tool. To this end Magnetic Resonance Relaxometry (MRR), which is able to quantitively characterize the tissues under investigation through their relaxation rates, seems extremely promising. Many studies assessed the feasibility of relaxometry as a diagnostic tool in human brain disorders, with the most promising results obtained in the evaluation of neurodegenerative diseases and in the oncologic field. However, despite such extensive literature in human medicine, due to the lack of standardized protocols and the need of high-field MRI scanners, to date few studies have been performed on companion animals. In this work, first we describe relaxometry applications in human neuropathology and their possible extension to companion animals both in the experimental and clinical fields. Then, we present two experiments performed on a typical standard clinical scanner operating at 0.25 T to show that, despite the low field intensity, this technique may be promising even in the clinical setup. We tested the relaxometry protocol in a phantom study and then applied it to a real clinical case study. The results showed that this protocol used on a phantom led to a higher contrast, as compared to the standard approach. Furthermore, when applied to a real case study, this protocol revealed brain lesions undetected by the standard technique which were confirmed by a histopathological examination. These preliminary results are encouraging and support the development of this approach as an advanced diagnostic tool even in a clinical setting where low field MRI scanners are typically employed
Guanidinium chloride induced unfolding of a hemocyanin subunit from Carcinus aestuarii - II. Holo form
No full textThe effects of guanidinium hydrochloride (GuHCl) on the functional and structural properties of a 75-kDa, functionally active hemocyanin (Hc) subunit isolated from the crab Carcinus aestuarii (holo-CaeSS2) were investigated. The holo form of the protein contains two copper ions in the active site and is capable of reversibly binding dioxygen. The present results are compared with those previously described for the
corresponding functionally inactive subunit (apo-CaeSS2), devoid of the two active site copper ions (accompanying paper [R. Favilla, M. Goldoni, A. Mazzini, M. Beltramini, P. Di Muro, B. Salvato, paper published in this issue]). As with apo-CaeSS2, both equilibrium and kinetic unfolding measurements were carried out using light scattering (LS), circular dichroism, intrinsic and extrinsic fluorescence (IF and EF, respectively). In addition here, absorbance spectroscopy was exploited to evaluate oxygen binding by holo-CaeSS2. These data were combined with those relative to the protein copper content to obtain information on the stability of the active site as a function of denaturant concentration. The different techniques used revealed several unfolding transitions. At GuHCl < 1 M, an appreciable increase of LS intensity was observed, about an order of magnitude lower than with apo-CaeSS2, suggesting some reversible protein aggregation. A first cooperative transition as a function of GuHCl was detected as an increase of intensity of the protein IF (C1/2 = 1 M), followed by a second transition, characterised by a
small intensity decrease and a red shift of the emission maximum (C1/2 = 1.4 M). Cooperative transitions with C1/2 values near 1.4 M GuHCl were also detected by following the decrement of: (a) EF intensity of anilino-1 naphtalenesulphonate (ANS) bound to the protein; (b)
absorbance at 340 nm, typical of oxy holo-CaeSS2; (c) copper-to-protein stoichiometry. A transition at higher GuHCl (C1/2 = 1.8 M) was also observed by far UV circular dichroism (far UV CD) and related to global unfolding. Unfolding kinetics was also studied using the fluorescence stopped-flow technique. All traces were best fitted by a sum of three or four exponential terms, depending on GuHCl concentration. A
comprehensive unfolding model is proposed, which accounts for most of the complex behaviour of this protein subunit, including oxy and deoxy native and aggregation-prone intermediates, a highly fluorescent intermediate, molten globule-like apo and unfolded species
Dissociation kinetics of hemocyanins from Octopus vulgaris
No full textThe native form of hemocyanin Hc. from Octopus Íulgaris can be completely dissociated, at alkaline pH and in thepresence of EDTA, from 49S decamers to 11S monomers. The kinetics of this process was studied, using a Bio-Logicstopped flow system, by following the time dependence of the 450-nm light intensity, scattered at 908, in the 7.9–8.8 pHrange. All experimental traces were best fitted by a sum of three exponential decay functions. We then tried to best fit thesedecay functions with a series of kinetic models, the best of them resulting in one whose dissociation of decamers tomonomers takes place in three consecutive and irreversible steps, with a highly cooperative step concerning dissociation ofoctamers to dimers, which appears to be the only intermediate species. This model was preferred over several others, notonly for the best norm value but also for the best accordance between each calculated and experimental kinetic parameterrate constants and amplitudes.. Although other more complex models may be considered, our best fit model represents thesimplest one, which is able to describe the observed dissociation kinetics.[...
Dementia-friendly intervention for hospitalized older adults with cognitive impairments: results of the Italian Dementia-Friendly Hospital Trial (IDENTITÀ)
No full textObjective: To evaluate whether a short training focused on improving dementia care practices of the hospital staff was able to counteract functional loss and to decrease negative outcomes at discharge among hospitalized older adults with cognitive impairment. Method: Sixty-eight hospitalized participants aged 65 and over with cognitive impairment were included in the study, allocated in the control group (n = 34) and intervention group (n = 34). The intervention consisted of a short training of the hospital staff aimed at improving the management of patients with cognitive impairment. Participants were evaluated within 48 h of hospital admission and at discharge using a battery of tests including Barthel Index, Mini-Mental State Examination, and Hospital Anxiety and Depression Scale. Results: The intervention group demonstrated shorter hospital length of stay and a maintenance of the functional status at discharge compared to the control group. We observed no differences in cognitive ability between the two groups, and a trend towards a decrease of anxious symptoms in the intervention group compared to the control group. Conclusion: The results suggest that an intervention, focused on improving dementia care practices in healthcare staff, has the potential to improve the outcomes for hospitalized older adults with cognitive impairment
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Pericardial Patch as a Palliative Treatment in Three Dogs Affected by Unresectable Cardiac Tumor
Full text linkThis report is aimed at describing a pericardial patch for unresectable cardiac tumors as a palliative technique to prevent pleural effusion. Each dog underwent the same diagnostic protocol including a cardiological assessment, hematology and biochemistry profile, urinary test, abdominal and heart ultrasonography and chest radiographs. Computed tomography was always performed in order to exclude any potential metastatic lesions. All dogs underwent open pericardiectomy: The pericardium was opened and transposed on the mass according to its shape. Biopsy of the mass was always performed. Histopathological evaluation of the masses described two HAS and one chemodectoma. Chemotherapy protocol includes doxorubicin that was weekly administered. Dogs with HSA survived 65 and 85 days respectively without pleural effusion, while the dog with chemodectoma died after six months for reasons unrelated to the tumor. No evidence of pleural effusion was observed during the heart recheck, monthly performed. Pericardial patch is a potential choice as a palliative treatment for unresectable cardiac tumors. No pleural effusion was seen in three dogs affected by unresectable cardiac tumors
Dissociation kinetics of hemocyanin from Octopus vulgaris
No full textThe native form of hemocyanin (Hc) from Octopus vulgaris can be completely dissociated, at alkaline pH and in the presence of EDTA, from 49S decamers to 11S monomers. The kinetics of this process was studied, using a Bio-Logic stopped flow system, by following the time dependence of the 450-nm light intensity, scattered at 90 degrees, in the 7.9-8.8 pH range. All experimental traces were best fitted by a sum of three exponential decay functions. We then tried to best fit these decay functions with a series of kinetic models, the best of them resulting in one whose dissociation of decamers to monomers takes place in three consecutive and irreversible steps, with a highly cooperative step concerning dissociation of octamers to dimers, which appears to be the only intermediate species. This model was preferred over several others, not only for the best norm value but also for the best accordance between each calculated and experimental kinetic parameter (rate constants and amplitudes). Although other more complex models may be considered, our best fit model represents the simplest one, which is able to describe the observed dissociation kinetics
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