Spermine Oxidase-Substrate Electrostatic Interactions: The Modulation of Enzyme Function by Neighboring Colloidal ɣ-Fe2O3

Protein-nanoparticle hybridization can ideally lead to novel biological entities characterized by emerging properties that can sensibly differ from those of the parent components. Herein, the effect of ionic strength on the biological functions of recombinant His-tagged spermine oxidase (i.e., SMOX) was studied for the first time. Moreover, SMOX was integrated into colloidal surface active maghemite nanoparticles (SAMNs) via direct self-assembly, leading to a biologically active nano-enzyme (i.e., SAMN@SMOX). The hybrid was subjected to an in-depth chemical-physical characterization, highlighting the fact that the protein structure was perfectly preserved. The catalytic activity of the nanostructured hybrid (SAMN@SMOX) was assessed by extracting the kinetics parameters using spermine as a substrate and compared to the soluble enzyme as a function of ionic strength. The results revealed that the catalytic function was dominated by electrostatic interactions and that they were drastically modified upon hybridization with colloidal ɣ-Fe2O3. The fact that the affinity of SMOX toward spermine was significantly higher for the nanohybrid at low salinity is noteworthy. The present study supports the vision of using protein-nanoparticle conjugation as a means to modulate biological functions.

Thiol functionalised gold nanoparticles loaded with methotrexate for cancer treatment: From synthesis to in vitro studies on neuroblastoma cell lines

HYPOTHESIS

Colloidal gold nanoparticles (AuNPs) functionalised with hydrophilic thiols can be used as drug delivery probes, thanks to their small size and hydrophilic character. AuNPs possess unique properties for their use in nanomedicine, especially in cancer treatment, as diagnostics and therapeutic tools.

EXPERIMENTS

Thiol functionalised AuNPs were synthesised and loaded with methotrexate (MTX). Spectroscopic and morphostructural characterisations evidenced the stability of the colloids upon interaction with MTX. Solid state (GISAXS, GIWAXS, FESEM, TEM, FTIR-ATR, XPS) and dispersed phase (UV-Vis, DLS, ζ-potential, NMR, SAXS) experiments allowed to understand structure-properties correlations. The nanoconjugate was tested in vitro (MTT assays) against two neuroblastoma cell lines: SNJKP and IMR5 with overexpressed n-Myc.

FINDINGS

Molar drug encapsulation efficiency was optimised to be >70%. A non-covalent interaction between the π system and the carboxylate moiety belonging to MTX and the charged aminic group of one of the thiols was found. The MTX loading slightly decreased the structural order of the system and increased the distance between the AuNPs. Free AuNPs showed no cytotoxicity whereas the AuNPs-MTX nanoconjugate had a more potent effect when compared to free MTX. The active role of AuNPs was evidenced by permeation studies: an improvement on penetration of the drug inside cells was evidenced.

Acidic Shift of Optimum pH of Bovine Serum Amine Oxidase upon Immobilization onto Nanostructured Ferric Tannates

Protein–nanoparticle hybrids represent entities characterized by emerging biological properties that can significantly differ from those of the parent components. Herein, bovine serum amine oxidase (i.e., BSAO) was immobilized onto a magnetic nanomaterial constituted of surface active maghemite nanoparticles (i.e., SAMNs, the core), surface-modified with tannic acid (i.e., TA, the shell), to produce a biologically active ternary hybrid (i.e., SAMN@TA@BSAO). In comparison with the native enzyme, the secondary structure of the immobilized BSAO responded to pH variations sensitively, resulting in a shift of its optimum activity from pH 7.2 to 5.0. Conversely, the native enzyme structure was not influenced by pH and its activity was affected at pH 5.0, i.e., in correspondence with the best performances of SAMN@TA@BSAO. Thus, an extensive NMR study was dedicated to the structure–function relationship of native BSAO, confirming that its low activity below pH 6.0 was ascribable to minimal structural modifications not detected by circular dichroism. The generation of cytotoxic products, such as aldehydes and H₂O₂, by the catalytic activity of SAMN@TA@BSAO on polyamine oxidation is envisaged as smart nanotherapy for tumor cells. The present study supports protein–nanoparticle conjugation as a key for the modulation of biological functions.

Bovine Serum Amine Oxidase and Polyamine Analogues: Chemical Synthesis and Biological Evaluation Integrated with Molecular Docking and 3-D QSAR Studies

Natural polyamines (PAs) are key players in cellular homeostasis by regulating cell growth and proliferation. Several observations highlight that PAs are also implicated in pathways regulating cell death. Indeed, the PA accumulation cytotoxic effect, maximized with the use of bovine serum amine oxidase (BSAO) enzyme, represents a valuable strategy against tumor progression. In the present study, along with the design, synthesis, and biological evaluation of a series of new spermine (Spm) analogues (1-23), a mixed structure-based (SB) and ligand-based (LB) protocol was applied. Binding modes of BSAO-PA modeled complexes led to clarify electrostatic and steric features likely affecting the BSAO-PA biochemical kinetics. LB and SB three-dimensional quantitative structure-activity relationship (Py-CoMFA and Py-ComBinE) models were developed by means of the 3d-qsar.com portal, and their analysis represents a strong basis for future design and synthesis of PA BSAO substrates for potential application in oxidative stress-induced chemotherapy.

[Spontaneous remission of visceral metastases of hypernephroma after nephrectomy. Description of a case and review of pathogenetic hypotheses]

We describe an absolutely spontaneous regression of visceral metastases from a renal carcinoma, following nephrectomy, in a 46 years old patient, who is at present in a complete uninterrupted remission for 39 months. After a literature review we point out the rarity of this event and emphasize its absolute spontaneity. Moreover, we suggest some considerations about the possible pathogenetic mechanisms of this unexpectedly positive outcome. Between these, because of the strongly positive psychologic attitude of the patient, the psycho-neuro-immunologic one is suggestive.

Changing clinical presentation of multiple myeloma

We compared the presentation features of three series of patients with multiple myeloma diagnosed between 1960 and 1971 (Kyle R, Mayo Clin Proc, 1975, 50, 29, n = 869), 1972 and 1986 (Clinica Medica, University of Pavia, n = 345) and 1987 and 1990 (Cooperative Group for Study and Treatment of Multiple Myeloma, n = 341). In the most recently diagnosed patients, the percentage of those who had symptoms related to multiple myeloma (i.e. any of bone pain, systemic symptoms, disturbances related to hypercalcemia, neurological involvement and hyperviscosity) was reduced (90 vs. 86 vs. 66%) (P less than 0.001), while the percentage of asymptomatic patients diagnosed by chance was increased (not reported, and 14 vs. 34%). In the most recent series, a lower percentage of spontaneous bone pain (68 vs. 60 vs. 37%, P less than 0.001) paralleled a lower incidence of advanced bone disease (osteolyses and pathological fractures, 60 vs. 64 vs. 34%), and renal failure (serum creatinine greater than 1.2 mg/dl) was also less common (56 vs. 44 vs. 33%, P less than 0.01), at least partially due to a decreased incidence of both hypercalcemia (30 vs. 20 vs. 18%, P less than 0.001) and of hyperuricemia (serum uric acid greater than 7 mg/dl, 47 vs. 32 vs. 26%, P less than 0.01). Systemic symptoms (weakness, infections, fever or weight loss) were reported more seldom by recently diagnosed patients, due to a decreased frequency of anaemia (haemoglobin less than 12 g/dl), leukopenia and thrombocytopenia, as well as of the systemic effects of bone pain and of renal insufficiency. These data indicate that multiple myeloma is diagnosed earlier now than in the past, and this must be taken into account when comparing survival data in treated series.

A plea to overcome the concept of "staging" and related inadequacy in multiple myeloma

From a retrospective multivariate study on 107 multiple myeloma (MM) patients, serum beta 2-microglobulin (beta 2M) proved to be the best prognostic discriminator, better than each of the currently used staging systems (Durie and Salmon's [DS], Merlini, Waldenström and Jayakar's [MWJ] and the British Medical Research Council's [BMRC]). The predictive ability of each staging system is better improved by combining consideration of beta 2 M as a continuous rather than a binary variable (even at its best prognostic cut-off). The combination of BMRC with beta 2 M demonstrated the highest prognostic value, followed by those involving DS or MWJ. Ease and measurability of clinical parameters at diagnosis, parametric type of statistical model assumed for description of survival, and supply of direct estimate of expected survival are the characteristics of the MWJ system that suggest it is best able to integrate beta 2 M correctly in a prognostic index. The basic concepts and the clinical use of the available staging systems for MM are criticized along the following lines: a) the need to include new and homogeneously weighted parameters in future prognostic systems -b) the lack of direct correspondence between treatment requirements (according to stage) and available therapeutic resources -c) evidence of the rough stratification of the actual survival expectancy, as permitted by the current staging systems. A direct, and as accurate as possible estimate of prognosis--based on easy and measurable parameters evaluable at diagnosis--should replace the current classification of patients according to stages. This estimate should mark the clinical evaluation at diagnosis, should flexibly indicate treatment even according to different protocols or centers, and should allow very accurate statistical corrections for different survival expectancy at diagnosis when evaluating different treatments in clinical trials.

Night sweats in Hodgkin's disease. A manifestation of preceding minor febrile pulses

The authors verified the hypothesis regarding an unawareness of possible febrile alterations during night sleep in patients with Hodgkin's disease who complain of night sweats as their only symptom. In these patients, body temperature was monitored by means of a 0.01 degrees C-sensitive linear transducer coupled with a digital multimeter. The palm of the hand (after it was passively closed in a fist by a full bandage) was the body site where temperature measurement was found to be most comfortable for a sleeping patient and independent of movements during sleep. A good correlation was found between the hand temperature taken with this technique and oral temperature. Of six patients with sweating as their only symptom, sweating recurred during the night in four and during the afternoon in the other two. In all patients sweating was preceded by a critical 0.5 to 1.5 degrees C increase in hand temperature, which took place no more than 30 minutes before sweating. Those with nocturnal sweats awakened during the subsequent sweating-related, rapid temperature decrease. These results are consistent with the occurrence of slight unperceived febrile pulses that precede sweating. The only peculiarity of night sweats consists in the higher probability that a preceding slight temperature rise may not be perceived by a sleeping patient, who is more likely to be awakened by the discomfort of the subsequent sweating. This would also explain the small prognostic significance of these sweats, which is the same as that of the preceding fever. These results are discussed in light of the increasing clinical evidence that patients with Hodgkin's disease are often affected by an instability of the thermoregulatory hypothalamic centers.

Ploidy and proliferative activity measurement by flow cytometry in non-Hodgkin's lymphomas. Do speculative aspects prevail over clinical ones?

Paraffin-embedded lymph node biopsies from 107 patients with newly diagnosed non-Hodgkin's lymphomas were examined for cell DNA content and proliferative activity (as percentage of S-phase cells) by means of flow cytometry. Patients were diagnosed between 1975 and 1985 and were homogeneously treated according to the grade of histologic malignancy. Cytofluorimetric data were studied with regard to their correlation with histology (classified and reviewed according to both Kiel and Working Formulation criteria), clinical stage, presence of constitutional symptoms, presence of bulky disease, sex, age, and the following laboratory data measured at diagnosis: erythrocyte sedimentation rate, hemoglobin, serum lactic dehydrogenase and serum albumin concentration. Aneuploidy was more frequent in the high grade malignant subtypes and in the miscellaneous group but showed no correlations with the other clinical parameters studied. Proliferative activity demonstrated a wide variation of data but a trend was evident toward higher proliferative values in the more severe histologic subtypes. The survival discrimination allowed by high- and low-grade malignant histology is exactly reproduced when highly and slowly proliferating lymphomas are considered (greater than or less than or equal to 12% of S-phase cells). These results, analyzed with those in the literature, suggest that measurements of ploidy and proliferative activity add little independent information to what is already provided by current histologic classifications, mainly as far as clinical evaluation and prognosis are concerned. Cytokinetic-aided therapeutic choices can be usefully proposed in a restricted number of cases. Improvement of the available lymphoma classifications through a better integration of ploidy and cytokinetic data with immunologic, genetic and histologic findings is still an object to be pursued in cytometric studies.