Asymmetrical Brain Plasticity: Physiology and Pathology.

The brain is inherently asymmetrical. How that attribute, manifest both structurally (volumetric, cytological, molecular) as well as functionally, relates to cognitive function, is not fully understood. Since the early descriptions of Paul Broca and Marc Dax it has been known that the processing of language in the brain is fundamentally asymmetrical. Contemporary imaging studies have corroborated early observations, and have also revealed significant functional links to multiple other systems, such as those sub serving memory or emotion. Recent studies have demonstrated that laterality is both plastic and adaptive. Learning and training have shown to affect regional changes in asymmetry, such as that observed in the volume of the planum temporale associated with musical practice. Increasing task complexity has been demonstrated to induce recruitment of contralateral regions, suggesting that laterality is a manifestation of functional reserve. Indeed, in terms of cognitive function, successful aging is often associated with a reduction of asymmetrical activity. The goal of this review is to survey and critically appraise the current literature addressing brain laterality, both morphological and functional, with particular emphasis on the asymmetrical plasticity associated with environmental factors and training. The plastic recruitment of contralateral areas associated with aging and unilateral lesions will be discussed in the context of the loss of asymmetry as a compensatory mechanism, and specific instances of maladaptive plasticity will be explored.

A novel quantitative approach for evaluating contact mechanics of meniscal replacements.

One of the functions of the meniscus is to distribute contact forces over the articular surfaces by increasing the joint contact areas. It is widely accepted that total/partial loss of the meniscus increases the risk of joint degeneration. A short-term method for evaluating whether degenerative arthritis can be prevented or not would be to determine if the peak pressure and contact area coverage of the tibial plateau (TP) in the knee are restored at the time of implantation. Although several published studies already utilized TP contact pressure measurements as an indicator for biomechanical performance of allograft menisci, there is a paucity of a quantitative method for evaluation of these parameters in situ with a single effective parameter. In the present study, we developed such a method and used it to assess the load distribution ability of various meniscal implant configurations in human cadaveric knees (n=3). Contact pressures under the intact meniscus were measured under compression (1200 N, 0 deg flexion). Next, total meniscectomy was performed and the protocol was repeated with meniscal implants. Resultant pressure maps were evaluated for the peak pressure value, total contact area, and its distribution pattern, all with respect to the natural meniscus output. Two other measures--implant-dislocation and implant-impingement on the ligaments--were also considered. If any of these occurred, the score was zeroed. The total implant score was based on an adjusted calculation of the aforementioned measures, where the natural meniscus score was always 100. Laboratory experiments demonstrated a good correlation between qualitative and quantitative evaluations of the same pressure map outputs, especially in cases where there were contradicting indications between different parameters. Overall, the proposed approach provides a novel, validated method for quantitative assessment of the biomechanical performance of meniscal implants, which can be used in various applications ranging from bench testing of design (geometry and material of an implant) to correct implant sizing.

How do normals move during prolonged wheelchair-sitting?

The clinical practice for minimizing the risk of pressure sores (PS) is to relief pressures under bony prominences of immobilized patients by changing their postures frequently. The US Department of Health advises to relief sitting pressures at least every 1 hour, and every 15 minutes for individuals who are body-abled. Surprisingly, there is paucity of information in the literature concerning motion of healthy subjects during prolonged sitting, which can be compared with these recommendations. Considering that healthy individuals are able to sit for hours without suffering injuries, such information seems particularly important. Accordingly, our objective was to measure frequency of postural changes and extent of motion during postural changes among healthy subjects who sit in a wheelchair (N=10), in order to provide information that is missing in the literature of PS biomechanics. Subjects were asked to sit comfortably for 90 minutes, during which their trunk's frontal and sagittal motions and sitting pressures were measured. We found that normals change their posture every 9 +/- 6 minutes in the sagittal plane, and independently, every 6 +/- 2 minutes in the frontal plane. Shoulders, thoracic-spine and lumbar-spine frontal plane motions were 8 +/- 4 degrees , 14 +/- 7 degrees and 15 +/- 7 degrees , respectively, and sagittal trunk-thigh movement was 10.3 +/- 7 degrees . The frequency of postural changes in normals, measured herein, was higher than frequencies reported in the literature for patients who suffered PS. This small study population therefore supports the hypothesis that prolonged immobilization contributes to PS onset.

In vivo muscle stiffening under bone compression promotes deep pressure sores.

Pressure sores (PS) in deep muscles are potentially fatal and are considered one of the most costly complications in spinal cord injury patients. We hypothesize that continuous compression of the longissimus and gluteus muscles by the sacral and ischial bones during wheelchair sitting increases muscle stiffness around the bone-muscle interface over time, thereby causing muscles to bear intensified stresses in relentlessly widening regions, in a positive-feedback injury spiral. In this study, we measured long-term shear moduli of muscle tissue in vivo in rats after applying compression (35 KPa or 70 KPa for 1/4-2 h, N = 32), and evaluated tissue viability in matched groups (using phosphotungstic acid hematoxylin histology, N = 10). We found significant (1.8-fold to 3.3-fold, p < 0.05) stiffening of muscle tissue in vivo in muscles subjected to 35 KPa for 30 min or over, and in muscles subjected to 70 KPa for 15 min or over. By incorporating this effect into a finite element (FE) model of the buttocks of a wheelchair user we identified a mechanical stress wave which spreads from the bone-muscle interface outward through longissimus muscle tissue. After 4 h of FE simulated motionlessness, 50%-60% of the cross section of the longissimus was exposed to compressive stresses of 35 KPa or over (shown to induce cell death in rat muscle within 15 min). During these 4 h, the mean compressive stress across the transverse cross section of the longissimus increased by 30%-40%. The identification of the stiffening-stress-cell-death injury spiral developing during the initial 30 min of motionless sitting provides new mechanistic insight into deep PS formation and calls for reevaluation of the 1 h repositioning cycle recommended by the U.S. Department of Health.

[Diffusion of ulcers in the diabetic foot is promoted by stiffening of plantar muscular tissue under excessive bone compression]. / Ausbreitung von Ulzerationen im diabetischen Fuss. Begünstigung durch Verhärtung des plantaren Muskelgewebes bei überhöhter Druckbelastung in der Umgebung der Knochen.

The abnormally elevated plantar pressures under the bony prominences of the diabetic foot (mainly under the medial metatarsal heads and calcaneus) were associated with intensified internal stresses in the deep soft tissues padding these bones. In this study, we tested changes in mechanical properties of muscular tissue after exposure to the internal stress levels typically developing under the first and second metatarsal heads in the load bearing diabetic foot (40-80 KPa). The gracilis muscles of anesthetized rats were subjected to constant external pressures of 35 and 70 KPa for 2 h, which caused average internal compression stresses of 40 and 80 KPa, respectively, within the living gracilis. The animals were then killed and the tangent elastic moduli of the harvested gracilis were measured in uniaxial tension at strains of 2.5%, 5% and 7.5%. Tangent moduli of gracilis muscles exposed to internal compression of 40-80 KPa in vivo ( n=6) were 1.6-fold stiffer ( p<0.05) than those of controls ( n=6). These abnormally stiff mechanical properties were incorporated into a finite element (FE) model of the plantar tissue under the second ray of the foot, and were shown to increase the magnitude of deep internal stresses and project elevated stresses to larger regions. Hence, the integration of animal model data with FE simulations indicates a mechanism of plantar tissue deterioration in the diabetic foot, where muscles exposed to critical stresses respond with increased stiffness which then further intensifies the deep plantar stresses. This suggests a new positive feedback mechanism for the diffusion of ulcers and the atrophy of intrinsic plantar muscles in the diabetic foot, where the injury spreads from deep muscles to the skin surface by an evolving mechanical stress wave.

Mechanical compression-induced pressure sores in rat hindlimb: muscle stiffness, histology, and computational models.

Pressure sores affecting muscles are severe injuries associated with ischemia, impaired metabolic activity, excessive tissue deformation, and insufficient lymph drainage caused by prolonged and intensive mechanical loads. We hypothesize that mechanical properties of muscle tissue change as a result of exposure to prolonged and intensive loads. Such changes may affect the distribution of stresses in soft tissues under bony prominences and potentially expose additional uninjured regions of muscle tissue to intensified stresses. In this study, we characterized changes in tangent elastic moduli and strain energy densities of rat gracilis muscles exposed to pressure in vivo (11.5, 35, or 70 kPa for 2, 4, or 6 h) and incorporated the abnormal properties that were measured in finite element models of the head, shoulders, pelvis, and heels of a recumbent patient. Using in vitro uniaxial tension testing, we found that tangent elastic moduli of muscles exposed to 35 and 70 kPa were 1.6-fold those of controls (P < 0.05, for strains /=5%). Histological (phosphotungstic acid hematoxylin) evaluation showed that this stiffening accompanied extensive necrotic damage. Incorporating these effects into the finite element models, we were able to show that the increased muscle stiffness in widening regions results in elevated tissue stresses that exacerbate the potential for tissue necrosis. Interfacial pressures could not predict deep muscle (e.g., longissimus or gluteus) stresses and injuring conditions. We conclude that information on internal muscle stresses is required to establish new criteria for pressure sore prevention.

[Myofibroblastoma of the male breast. Apropos of a case]. / Miofibroblastoma della mammella maschile. A proposito di un caso.

A case of male breast myofibroblastoma, personally observed, is described. Preoperative examinations have a limited diagnostic value. Only histological study, with immunohistochemical stain, allows to make a right diagnosis and to distinguish this tumor from other, benign or malignant mesenchymal neoplasms.

Validation of object-induced MR distortion correction for frameless stereotactic neurosurgery.

Spatial fidelity is a paramount issue in image guided neurosurgery. Until recently, three-dimensional computed tomography (3D CT) has been the primary modality because it provides fast volume capture with pixel level (1 mm) accuracy. While three-dimensional magnetic resonance (3D MR) images provide superior anatomic information, published image capture protocols are time consuming and result in scanner- and object-induced magnetic field inhomogeneities which raise inaccuracy above pixel size. Using available scanner calibration software, a volumetric algorithm to correct for object-based geometric distortion, and a Fast Low Angle SHot (FLASH) 3D MR-scan protocol, we were able to reduce mean CT to MR skin-adhesed fiducial marker registration error from 1.36 to 1.09 mm. After dropping the worst one or two of six fiducial markers, mean registration error dropped to 0.62 mm (subpixel accuracy). Three dimensional object-induced error maps present highest 3D MR spatial infidelity at the tissue interfaces (skin/air, scalp/skull) where frameless stereotactic fiducial markers are commonly applied. The algorithm produced similar results in two patient 3D MR-scans.

[Primary lymphoma of the breast. Three cases of non-Hodgkin lymphoma]. / Il linfoma primitivo della mammella. A proposito di 3 casi di linfoma non-Hodgkin.

Primary and sole breast lymphoma is a very rare disease. With the review of our series of 616 cases operated on for breast cancer, only 3 cases (0.48%) of primary breast non-Hodgkin lymphoma (LNH) have been observed. The authors outline the problems concerning diagnosis and therapy of this rare disease: pathological and immunohistochemical aspects are discussed. They stress the importance of staging in order to plan a correct multidisciplinary approach.

[Our experience in the surgical treatment of early breast cancer. Results of a prospective study of 204 cases]. / La nostra esperienza nel trattamento chirurgico del carcinoma mammario iniziale. Risultati di uno studio prospettico su 204 casi.

The authors report the results of a prospective study on 204 patients (1980-1993) affected by early infiltrating breast cancer (size pounds 2 cm) as a part of a surgical series of 608 cases. 53 cases who underwent QUART (25.9%) and 151 cases (74.1%) who underwent mastectomy modified according to Patey have been collected. 10 years actuarial survival has been respectively 79% after extensive surgery and 78% after conservative treatment. Local recurrences have been observed in 9 cases after meticulous follow-up (median 74.8 months, range 12-178): 3 (5.66%) patients after QUART and 6 (3.97%) after mastectomy; furthermore 1 patients after a conservative treatment (1.88%) has developed a second tumor at the same side probably dependent on the presence in the primary tumor of an extensive intraductal component. No correlations between histological features, grading, positive nodes, receptor status and local recurrences have been found. Only the age of patients looks significantly correlated with frequency of recurrences: 44.45% of local recurrences have been observed in patients less than 45 years old. Local recurrences after QUART have obliged, in all cases, to a radical mastectomy. Furthermore, frequency of distant metastases has been considered: after QUART percentage is lower (9.43%) than after radical mastectomy (13.9%). This consideration looks correlated with the longer follow-up of the later group. A multidisciplinary approach is advised but the most important role is played by surgery. In conclusion it is outlined that conservative surgery is addressed to selection and consenting patients.

[Natural history of breast cancer: lobular carcinoma versus ductal carcinoma in our experience]. / A proposito della storia naturale del cancro della mammella: carcinoma lobulare versus carcinoma duttale nella nostra esperienza.

Aim of the study is to evaluate the biology, the clinical evolution and the prognosis of lobular carcinoma of the breast. We retrospectively evaluated the patients treated in our institution during the last 13 years. 117 patients with lobular carcinoma of the breast and 117 patients, randomized out of 397 patients with 'classical' pattern of ductal carcinoma were compared. Age distribution, type of surgery, tumor size, TNM stage, axillary lymph node involvement, multifocality, multiple breast cancers, local and distant recurrences, overall survival and disease-free survival have been evaluated. There was not a significant difference in tumor size, lymph node involvement, stage distribution, estrogens and progesterone receptors status, local and distant recurrences. The only significant differences were found in multifocality and multiple breast cancers. The said difference does not seem to modify the overall survival and the disease-free survival that are the same in the two groups. Our research shows that tumor size and axillary lymph node status are the only elements that have to be considered in the choice of the surgical treatment and prognosis. It seems that the difference in distant metastatic pattern between lobular and ductal carcinoma is the distinctive feature in the follow-up of these patients.

[Ventrolateral hernias of the abdominal wall. The anatomicopathologic, clinical and therapeutic considerations]. / Le ernie ventro-laterali della parete addominale. Considerazioni anatomopatologiche, cliniche e terapeutiche.

Ventral lateral hernias of the abdominal wall are rare. On the basis of their location we can classify them as follows: hernias of the aponeurosis of the transversus muscle, hernias of the rectal sheath and transmuscular hernias of the iliac region. In a group of 3134 hernias of the abdominal wall observed in a period of 16 years, 11 ventral lateral hernias have been encountered (0.3%). The diagnosis often presents great difficulties as the symptoms and the clinical findings are not typical. They must be differentiated from hematomas of the rectus sheath, abscess or intra-abdominal processes. Echography and Computed Tomography have an important role in their detection. Nevertheless in some patients the true diagnosis is reached only intraoperatively. The treatment generally consists in surgical correction by layer closure of the fascial or muscular defect. In selected cases the use of prosthetic material and video laparoscopic repair are indicated.

[Liposarcoma of the spermatic cord]. / Liposarcoma del funicolo spermatico.

A case of well differentiated liposarcoma of the spermatic cord in a 80 year old man is presented. The preoperative diagnosis of spermatic cord liposarcoma is not easy; however, a careful comparison between clinical and ultrasonographic findings can lead to diagnostic suspicion. The treatment of choice is the excision of the liposarcoma associated with orchiectomy and high ligation of the spermatic cord to reduce the risk of recurrence. Postoperative radiotherapy may be indicated for poor differentiated liposarcomas.

Whiteness and tint formulas of the Commission Internationale de l'Eclairage: approximations in the Lab color space.

Linear approximations to the whiteness and tint formulas of the Commission Internationale de l'Eclairage (CIE) are presented in the CIE L*a*b* color system.

Central nervous system complications of cystosarcoma phyllodes.

BACKGROUND: Cystosarcoma phyllodes (CP) is an uncommon fibroepithelial breast neoplasm that rarely involves the central nervous system (CNS). METHODS: The authors encountered two patients with CNS metastases and reviewed the literature to identify reports of CP affecting the nervous system. Patients must have been reported in sufficient detail to characterize clinical course, extent of tumor burden, and histologic type of the primary tumor and metastasis to be included in the study. RESULTS: Eleven cases were identified from the literature, but only six were presented in sufficient detail for analysis. Including the current patients, the mean age of patients with CP metastases was 52 years. The time between initial diagnosis and CNS involvement was 5 years. Parenchymal brain metastases respond poorly to treatment, with a mean survival of 29 days, whereas survival is significantly longer with CNS involvement secondary to epidural extension of tumor from adjacent bony structures. Local recurrence or widespread metastases nearly always were present at the time of CNS involvement. CONCLUSIONS: Brain metastases from CP are refractory to therapy and carry a dismal prognosis. Patients with CP and brain metastases should undergo brain biopsy to exclude metastases from associated epithelial breast tumors, which have significantly better prognoses. Patients with compressive lesions arising from bone have a better prognosis and may benefit from aggressive management.

Functional and morphological effects of defibrotide on renal ischemia.

Defibrotide (Df) has been reported to protect various organs from ischemic damage. The aim of this study was to evaluate the effect of Df on renal function and morphology after warm kidney ischemia. Divided into two groups, 14 pigs underwent bilateral renal clamping for 90 min. One group (7 pigs) was treated with Df (32 mg/kg per h) for 6 h, whereas the control group received 5000 IU of heparin. Serum levels of blood urea nitrogen (BUN) and creatinine measured for 6 days were significantly higher in the control group (peak 26.8 +/- 16.7 vs 11.0 +/- 2.9 mmol/l and 501.2 +/- 351.4 vs 230.2 +/- 68.0 mumol/l P < 0.05). Renal biopsy evidenced a lesser extent of tubular and endothelial damage in Df-treated animals. In conclusion, Df provided relevant protection against renal ischemic injury.