Effect of ferric citrate on amyloid-beta peptides behavior.

Amyloid beta (Aß) aggregation and oxidative stress are two of the central events in Alzheimer's Disease (AD). Both these phenomena can be caused by the interaction of Aß with metal ions. In the last years the interaction between ZnII , CuII , and Aß was much studied, but between iron and Aß it is still little known. In this work we determine how three Aß peptides, present in AD, interact with FeIII -citrate. The three Aß peptides are: full length Aß1-42, an isoform truncated at Glutamic acid in position three, Aß3-42, and its pyroglutamated form AßpE3-42. Conformation and morphology of the three peptides, aggregated with and without FeIII -citrate were studied. Besides, we have determined the strength of the interactions Aß/FeIII -citrate studying the effect of ethylenediaminetetraacetic acid as chelator. Results reported here demonstrate that FeIII -citrate promotes the aggregation in all the three peptides. Moreover, Aspartic acid 1, Glutamic acid 3, and Tyrosine 10 have an important role in the coordination with iron, generating a more stable complex for Aß1-42 compared to that for the truncated peptides.

Navigated knee kinematics after cutting of the ACL and its secondary restraint.

PURPOSE: The purpose of this study is to evaluate the kinematics changes of the knee after cutting of the ACL with or without injury of the anterolateral structures. METHODS: In this study, the role of the ACL and one of the secondary restraints in controlling knee stability using a navigation system was evaluated. The kinematics of the knee was evaluated in different conditions of instability: ACL intact, after dissection of the posterolateral (PL) bundle, after dissection of the anteromedial (AM) bundle, and after lesion of the lateral capsular ligament (LCL). Anterior tibial translation and rotation were measured with a computer navigation system in 10 fresh-frozen cadaveric knees by use of a manual maximum load. Anterior translation was evaluated at 30°, 60°, and 90° of flexion; rotation at 0°, 15°, 30°, 45°, 60°, and 90°. RESULTS: Cutting the PL bundle does not increase anterior translation and rotation of the knee. Cutting the AM bundle significantly increased the anteroposterior (AP) translation at 30° and 60° (P = 0.01), but does not increase rotation of the knee. Cutting the LCL increased anterior translation at 60° (P = 0.04) and rotation at 30°, 45°, and 60° (P = 0.03). CONCLUSIONS: Within the testing conditions of this study, the PL bundle does not affect anterior translation and rotation of the knee; the AM bundle is the primary restraint of the anterior translation but does not affect rotation of the knee while the lesion of the LCL increases tibial rotation and could be related to the pivot shift phenomenon, so it is more correct and biomechanical valid to assess and repair the associated lesion of the antero-lateral structure of the knee at the time of ACL surgery.

Surgical access and damage extent after total hip arthroplasty influence early gait pattern and guide rehabilitation treatment.

AIM: Different surgical approaches are used in total hip arthroplasty. The present study confronted two surgical techniques, analysing functional recovery in terms of activities of daily living, and ambulation using gait analysis, after a standardized rehabilitation protocol. Our hypothesis was that the increased surgical damage could modify the gait pattern and functional recovery. METHODS: Thirty patients were randomly assigned to two homogeneous groups: Group A was treated with intermuscular minimally invasive surgery (MIS); Group B was treated with standard lateral transmuscular approach. Follow up was planned at 30 and 90 days. Instrumental evaluation using gait analysis and functional evaluation using validated scales were performed at follow up. RESULTS: No differences could be found as for functional scales. At the first follow up, the MIS approach proved to be the most favourable: data showed a longer duration of the swing phase, an improved range of motion of the non-treated hip, a reduced adduction (all P<0.005) and a correct timing of activation of the gluteus medium muscle on the treated side. At the second evaluation, gait analysis demonstrated some benefits of the intermuscular approach (a better flexion of both hips, and a minor obliquity of the pelvis during the terminal stance), but also advantages in the transmuscular group (better hip extension). CONCLUSION: Gait pattern after THA seems to be strictly dependent on surgical access and on the extent and location of surgical damage. It appears important to consider these elements in order to correctly manage the rehabilitation treatment after surgery.

Biomechanical evaluation of different anterior cruciate ligament fixation techniques for hamstring graft.

BACKGROUND: A number of anterior cruciate ligament (ACL) fixation techniques are currently in use. Slippage or failure of the graft by excessive loading or aggressive rehabilitation may result in an unstable knee. Load and slippage of the ACL graft varies according to the fixation technique used. METHODS: Graft slippage, load to failure, and stiffness were evaluated using an animal model. Six soft tissue ACL fixation techniques and bone cement as a fixation device were tested: group A, Endo Button CL-Bio RCI; group B, Swing Bridge-Evolgate; group C, Rigidfix-Intrafix; group D, Bone Mulch-Washer Lock; group E, Transfix-Retroscrew; group F, Transfix-Deltascrew; group G, Kryptonite bone cement. Maximum failure load, stiffness, and slippage at the 1st and 1000th cycles and mode of failure were evaluated. RESULTS: The maximum failure load was significantly higher in group B (1030 N) and significantly lower in group E (483 N) than in the others. The stiffness of group B (270 N/mm) was significantly higher than the others. As for the mode of failure, group C showed failure in the femoral side in all tests (four device ruptures and two tendon ruptures on the femoral side). All failures of the other groups occurred on the tibial side except one test in group A. All failures in group G were due to slippage of the tendons. CONCLUSION: Load to failure and stiffness was significantly different between the ACL fixation techniques. All but one of the fixation techniques showed sufficient properties for adequate postoperative rehabilitation. Bone cement used as a fixation device in soft tissue grafts did not seem to provide adequate initial fixation suitable for early rehabilitation after ACL reconstruction.

A lateral minimal-incision technique in total hip replacement: a prospective, randomizes, controlled trial.

Minimally invasive surgery has become a trend over the last few years in all aspects of orthopaedic surgery, including total hip arthroplasty. So-called mini-incision techniques involve limiting the length of the skin incision to 10 cm with use of either an anterior, lateral or posterior approach. Between March 2004 and December 2005 one hundred consecutive unilateral total hip replacements were performed by the same senior surgeon in our institute. All patients were randomly assigned to study group (group A) or control group (group B). In group A (50 patients) the skin incision was 8 cm; in group B (50 patients) the skin incision was standard (about 12-14 cm). Patient demographic data, including sex, age, height, weight, BMI, diagnosis and preoperative Harris hip score were recorded. Other criteria evaluated included the perioperative and postoperative complications, the surgical time, the blood loss, the length of the incision, the acetabular and stem positions, the length of hospital stay, Harris Hip Score (HHS) and the WOMAC osteoarthritis index at six months. No significant differences were found between the groups with respect to the average surgical time, the acetabular and stem position, the length of hospital stay and the Harris Hip Score (HHS) and the WOMAC osteoarthritis index at six months. A significant lower blood loss was found in the mini-incision group. A higher percentage of peri-operative complications was recorded in Group A (two stupor of sciatic nerve and one fracture of the greater trochanter). On the basis of our experience we could speculate that minimally invasive surgery should be directed to the new surgical approach with muscle sparing, instead of a shorter skin incision using standard approaches.

Conformation dependent pro-apoptotic activity of the recombinant human prion protein fragment 90-231.

The transition of prion protein from a mainly alpha-structured isoform (PrPC) to a beta sheet-containing protein (PrPSc) represents a major pathogenetic mechanism in prion diseases. To study the role of PrP structural conformation in prion-dependent neurodegeneration, we analysed the neurotoxicity of PrP in alpha and beta conformations, using a recombinant protein encompassing amino acids 90-231 of the human PrP (hPrP90-231). Using controlled thermal denaturation (53 degrees C, 1h) we converted hPrP90-231 in a structural isoform displaying PrPSc-related characteristics: high beta sheet content, increased aggregability and a slight increase in the resistance to protease K. In virtue of these structural changes, hPrP90-231 powerfully affected the survival of SH-SY5Y cells, inducing a caspase-3 and p38- dependent apoptosis. Conversely, in the native alpha-helix-rich conformation, hPrP90-231 did not show significant cell toxicity. The relationship between the structural state of hPrP90-231 and its neurotoxicity was demonstrated, inducing the thermal denaturation of the peptide in the presence of Congo red that prevented both the transition of hPrP90-231 into a beta-rich isoform and the acquisition of toxic properties. In conclusion, we report that the toxicity of hPrP90-231 is dependent on its three-dimensional structure, as is supposed to occur for the pathogen PrP during TSE.

Sequence specific peptidomimetic molecules inhibitors of a protein-protein interaction at the helix 1 level of c-Myc.

Our work is focused in the broad area of strategies and efforts to inhibit protein-protein interactions. The possible strategies in this field are definitely much more varied than in the case of ATP-pocket inhibitors. In our previous work (10), we reported that a retro-inverso (RI) form of Helix1 (H1) of c-Myc, linked to an RI-internalization sequence arising from the third alpha-helix of Antennapedia (Int) was endowed with an antiproliferative and proapoptotic activity toward the cancer cell lines MCF-7 and HCT-116. The activity apparently was dependent upon the presence of the Myc motif. In this work, by ala-scan mapping of the H1 portion of our molecules with D-aa, we found two amino acids necessary for antiproliferative activity: D-Lys in 4 and D-Arg in 5 (numbers refer to L-forms). In the natural hetero-dimer, these two side chains project to the outside of the four alpha-helix bundle. Moreover, we were able to obtain three peptides more active than the original lead. They strongly reduced cell proliferation and survival (RI-Int-VV-H1-E2A,S6A,F8A; RI-Int-VV-H1-S6A,F8A,R11A; RI-Int-VV-H1-S6A,F8A,Q13A): after 8 days at 10 muM total cell number was approximately 1% of the number of cells initially seeded. In these more potent molecules, the ablated side chains project to the inside in the corresponding natural four alpha-helix bundle. In the present work, we also investigated the behavior of our molecules at the biochemical level. Using both a circular dichroism (CD) and a fluorescence anisotropy approach, we noted that side chains projecting at the interior of the four alpha-helix bundle are needed for inducing the partial unfolding of Myc-H2, without an opening of the leucine zipper. Side chains projecting at the outside are not required for this biochemical effect. However, antiproliferative activity had the opposite requirements: side chains projecting at the outside of the bundle were essential, and, on the contrary, ablation of one side chain at a time projecting at the inside increased rather than decreased biological activity. We conclude that our active molecules probably interfere at the level of a protein-protein interaction between Myc-Max and a third protein of the transcription complex. Finally, CD and nuclear magnetic resonance (NMR) data, plus dynamic simulations, suggest a prevalent random coil conformation of the H1 portion of our molecules, at least in diluted solutions. The introduction of a kink (substitution with proline in positions 5 or 7) led to an important reduction of biological activity. We have also synthesized a longer peptido-mimetic molecule (RI-Int-H1-S6A,F8A-loop-H2) with the intent of obtaining a wider zone of interaction and a stronger interference at the level of the higher-order structure (enhanceosome). RI-Int-H1-S6A,F8A-loop-H2 was less active rather than more active in respect to RI-Int-VV-H1-S6A,F8A, apparently because it has a clear bent to form a beta-sheet (CD and NMR data).

Clinical presentation and outcome of pituitary adenomas in teenagers.

OBJECTIVE: Pituitary adenomas rarely occur in childhood and adolescence, but their mass effect and endocrine abnormalities can compromise both quality and length of life. In this study we evaluated the symptoms at onset and the long-term consequences induced in teenagers by functioning or nonfunctioning pituitary adenomas. DESIGN AND PATIENTS: Clinical, biochemical and neuroradiological data of 44 young patients (12 males and 32 females, aged 16.3 +/- 1.9 years at diagnosis) with pituitary adenomas were evaluated retrospectively at baseline and after therapy. Patients underwent surgery, radiotherapy and/or medical treatment depending on clinical history and endocrine secretion of the tumour. Follow-up ranged from 8 to 252 months (median 55 months). MEASUREMENTS: Baseline and dynamic pituitary function were evaluated in all cases at diagnosis and after treatments. Magnetic resonance imaging (MRI) or computed tomography (CT) scan were performed before therapy and during follow-up. Hormone levels were measured using commercial radioimmunologic or immunoradiometric methods. RESULTS: Pituitary macroadenomas (group 1) or microadenomas (group 2) were found in 61% and 39% of cases, respectively. Overall, 68% were PRL-secreting, 7% GH-secreting, 5% ACTH-secreting and 20% nonfunctioning. The most frequent symptoms at onset were oligoamenorrhoea (62%) and galactorrhoea (59%) in the girls, and headache (58%) in the boys. Pubertal development was delayed in 12/27 (44%) cases with macroadenoma. Growth failure was observed in 4/44 (9%) patients (3 in group 1 and 1 in group 2). At diagnosis, hypopituitarism was detected in 10/27 (37%) patients with macroadenoma. Surgery alone cured 4/18 (22%) and 4/9 (44%) patients in group 1 and group 2, respectively. Adjuvant therapies (second surgery and/or radiotherapy and/or medical treatment) cured the disease in 2/13 (15%) patients with macroadenoma and allowed a persistent normalization in other 4/13 (31%) and 2/4 (50%) cases in group 1 and group 2, respectively. Medical treatment alone cured 2/9 (22%) patients with PRL-secreting macroadenoma and normalized PRL levels in another six (66%) with macroprolactinoma and in 2/7 (28%) patients with microprolactinoma. CONCLUSION: Delay of growth was rarely observed in teenagers with pituitary adenomas. At the onset of the disease, many girls complained of oligoamenorrhoea and galactorrhoea, while headache and delay of pubertal development were the symptoms more frequently referred by boys. Surgery alone was effective in a minority of patients and adjuvant therapies were helpful to obtain the remission of the disease in many cases. In patients with PRL-secreting pituitary adenoma, medical treatment, both as first choice or as adjuvant therapy, normalizes serum PRL levels in 14/27 (52%) cases.

Benign central neurocytoma.

BACKGROUND: "Central neurocytoma" is classically considered as an intraventricular benign tumor, largely based on data from small retrospective series. The authors present prospective data on 12 patients with tumors diagnosed as central neurocytoma, to highlight the diverse nature of this tumor and challenge the classic notion. METHODS: Between 1991 and 1997, 12 patients had tumors diagnosed prospectively as "central neurocytoma". Clinical, radiologic, and histologic data were collected, and Karnofsky performance score was evaluated for each patient. Proliferation marker studies were performed using Ki-67 labeling index. RESULTS: In two patients, the tumors were located in atypical locations, namely, the parietal lobe and the spine. Aggressive behavior characterized by clinical and radiologic evidence of tumor progression was noted in two additional patients. In both these cases, unusually high proliferation rates of 5.3% and 11.2% were noted. Total excision of the tumor, when possible, was the treatment of choice. Postoperative radiotherapy to the residual tumor may be of benefit in patients with clinically aggressive tumors, or those with high proliferation rates. CONCLUSIONS: Given the findings of this study, it is suggested that the traditional concept of central neurocytoma as a benign intraventricular tumor warrants reconsideration.

Microdysgenesis with abnormal cortical myelinated fibres in temporal lobe epilepsy: a histopathological study with calbindin D-28-K immunohistochemistry.

Microdysgenesis is a microscopic cortical malformation reported to occur with varying incidence in surgical lobectomies from patients with temporal lobe epilepsy (TLE). It may act as a substrate for the seizures. Four patients are reported with TLE, hippocampal sclerosis and cortical microdysgenesis which was also characterized by the presence of abnormal myelinated fibres running tangentially in the superficial cortical laminae and closely associated with abnormal clusters of neurones. Similar abnormal cortical fibres have been described in other malformations of cortical development including polymicrogyria and focal cortical dysplasia and it is therefore likely that these fibres represent part of the microdysgenetic malformation not hitherto reported. The possibility is discussed that they may also be of functional significance in terms of influencing local seizure propagation and the secondary cortical neuronal loss observed, predominantly affecting layer II. Studies of calbindin interneuronal populations showed preservation of these cells in the microdysgenetic cortex, when compared with non-malformed temporal lobes, despite an overall reduction in cortical neuronal density. In addition, prominent numbers of neurogliaform calbindin-positive nerve cells were observed in the microdysgenesis cases and the nature of these cells is speculated upon.

Bilateral symmetrical enhancing brainstem lesions: an unusual presentation of primary CNS lymphoma.

We report a patient with a progressive brainstem syndrome, who on magnetic resonance imaging had large bilateral, symmetrical, contrast-enhancing, infratentorial space-occupying lesions. Biopsy of one of the lesions revealed this unusual appearance to be due to a primary central nervous system (CNS) lymphoma of B-cell type. Symmetry of lesions may be a clue to the diagnosis, perhaps reflecting the mechanism by which CNS lymphomas spread.

Hippocampal sclerosis with hypertrophy of end folium pyramidal cells.

Mesial temporal lobectomy for the treatment of intractable temporal lobe seizures may show dual pathologies for example hippocampal sclerosis (HCS) combined with a malformation. In a lobectomy specimen from a 40-year-old female with typical radiological and pathological features of HCS, an additional histopathological finding was the presence of hypertrophic pyramidal cells in the dentate hilus, in which cytoplasmic accumulations of phosphorylated neurofilament were demonstrated. Although these cells closely resembled dysplastic nerve cells of cortical dysplasia, we argue that the cytoskeletal abnormalities observed are a result of ongoing alterations to hippocampal circuitry in an evolving HCS.

TGF-beta1 binding protein-like modules of fibrillin-1 and -2 mediate integrin-dependent cell adhesion.

Human fibrillin, a major component of the extracellular matrix, exists as two highly homologous forms (fibrillin-1 and -2). Several modules of fibrillin are homologous to TGF-beta1 binding protein. Two of these modules, D25 (the 25th module of fibrillin-1 and -2 D segment) and D12 (the 12th module of fibrillin-2 D segment) contain the cell adhesion motif arginyl-glycyl-aspartyl (RGD). The ability of RGD to mediate adhesion to D25-1 and D12-2 was investigated using bacterially expressed fusion proteins. Human skin fibroblasts and murine L-cells were used in microassays of cell attachment and cell spreading on fibrillin fusion-protein substrata. Dose-dependent experiments and competitive inhibition by soluble RGD-containing peptides demonstrated that D25-1 and D12-2 mediate RGD-dependent cell adhesion. These results provide evidence for a cell adhesion function of fibrillin-2. Inhibition with anti-integrin antibodies showed that alpha(v) and beta3 integrins mediate adhesion to D25-1, while alpha3, alpha(v) and beta1 are involved in adhesion to D12-2. Binding of different receptors may elicit distinct cell signalling supporting the hypothesis that fibrillin-1 and fibrillin-2 have distinct roles.

Intradural neurotropic spread of malignant mesothelioma. Case report and review of the literature.

This 54-year-old man with a history of right-sided malignant mesothelioma presented with signs of a partial spinal cord syndrome. The tumor had invaded the lower trunk of the brachial plexus and spread along the T-1 nerve root beneath the arachnoid onto the spinal cord itself. Mesothelioma, despite its known predilection for local spread, is rarely encountered within the spinal canal. Neurotropism is commonly encountered in facial malignancies; however, it has never been reported to affect the brachial plexus and spinal cord.

Intracranial osteosarcomas: report of four cases and review of the literature.

Four cases of intracranial osteosarcoma are reported. In three cases the tumors were primary neoplasms arising from the sellar region, base of the occiput and the parieto-occipital area. One case represented osteosarcoma metastatic to the cerebellum, a site not previously described, from a primary tumor at the femur. In addition, the current literature on intracranial osteosarcoma is reviewed.

Human neutrophil Fc receptor-mediated adhesion under flow: a hollow fibre model of intravascular arrest.

Human polymorphonuclear cells (PMN) were found to adhere to a novel model of blood vessel wall-associated IgG. The internal surfaces of cellulose acetate hollow fibres, of comparable internal diameter to small blood vessels, were coated with normal serum human IgG, heat-aggregated IgG (HAIgG), laminin or fibrinogen. Under conditions of flow mimicking those in a small vessel, PMN were found to adhere markedly only to immunoglobulin-coated fibres. Arrest on HAIgG was inhibited by excess soluble IgG but not by bovine serum albumin (BSA), demonstrating that the adhesion was IgG-specific and presumably mediated by Fc gamma R on the PMN surface. Pre-adsorption of serum components onto HAIgG-coated fibres enhanced PMN arrest, due most probably to fixation of complement components by immobilized HAIgG, resulting in additional potential to entrap PMN via complement receptors such as CR3. Treatment of PMN with the regulatory neuropeptide substance P also enhanced adhesion to HAIgG-coated fibres and caused increased surface expression of Fc gamma RI, Fc gamma RII and Fc gamma RIII. A mouse cell line derived from L cells, hR4C6, stably transfected with human Fc gamma RII, was found to adhere under flow to HAIgG-coated fibres, whilst untransfected parent L cells did not. This adhesion was similarly inhibited by excess soluble IgG, confirming the capability of Fc gamma R to mediate cell arrest. The study strongly suggests that Fc gamma R may play an important role in intravascular PMN arrest and we speculate that in inflammatory diseases PMN may adhere via Fc gamma R to immobilized immunoglobulin on the vascular endothelium, with subsequent degranulation and tissue damage.

Cell adhesion molecules in oesophageal epithelium.

The distribution of a range of integrins, E-cadherin, and carcino-embryonic antigen (CEA) like molecules in normal human oesophageal epithelium was investigated immunohistochemically on frozen sections of endoscopic biopsy specimens. The integrin subunits alpha 2, alpha 3, alpha 6, alpha v, beta 1, and beta 5 were expressed throughout the epithelium. There was strong expression of alpha 2, alpha 3, and beta 1 subunits in the basal cell layer and for all the subunits studied the intensity of the staining decreased as cells moved towards the lumen. The heterodimer alpha v beta 3 was expressed weakly in the basal aspect of the basal cell layer only. The CEA molecules were not present in the basal cells layer but there was weak expression in the prickle cell layer and strong positivity in the mature functional layer. E-cadherin was found throughout the epithelium but was weakly expressed at the basal aspect of the basal cells layer and showed strong positivity in the prickle cell and squamous cell layers. These results indicate that cell-cell (E-cadherin, CEA) and cell-matrix (integrins) adhesion molecules show a well defined spatial pattern of immunoreactivity in the oesophageal mucosa and may play a part in the maintenance of normal tissue architecture and physiological homeostasis.