Intra-operative iodine-125 prostatic implant following bilateral pelvic lymphadenectomy

Sixty-five patients with prostatic adenocarcinoma Stages B and C were treated with intraoperative Iodine-125 prostatic implantation following bilateral pelvic lymphadenectomy. Pelvic nodal metastases were found in 31% of the patients: 23% ($\text{7}\text{31}$) in clinical Stage B1 disease, 29% ($\text{8}\text{28}$) in clinical Stage B2, and 83% ($\text{5}\text{6}$) in clinical Stage C. All the patients have been followed for a period of $\text{1}\text{1}\text{2}$ to 6 years. Serial digital rectal examination revealed complete regression of the palpable disease in 15% of the patients at 6 months, 47% at I year, and 87% at 2 years. Post-operative complications were also evaluated: 13% of the patients became sexually impotent, 11 % had impaired potency after the procedure, and 16% of patients complained of dry ejaculation; and 17% developed scrotal and/or penile swelling, which persisted up to 14 months, but usually subsided within 5 months. Two patients developed local recurrence. Both patients responded to subsequent external radiation therapy of 7000 rad in 11 to 14 weeks with clinical regression of palpable disease.     

Three new cases of salivary duct carcinoma in the palate: a radiologic investigation and review of the literature

Salivary duct carcinoma (SDC) is a rare, extremely aggressive malignancy arising in the ductal epithelium of the salivary glands. Radiologic investigations of and reports on minor salivary gland SDC are very rare. We present 3 cases of SDC of the palate with the attendant radiologic features and clinicopathologic findings. We also review English-language reports with radiologic findings regarding SDC and minor salivary gland SDC. MR imaging findings such as low signal intensity on T2-weighted images, infiltrative margins, and poor enhancement, in particular, should be recognized as indicators of high-grade malignancy such as SDC and, as such, should be considered when making a differential diagnosis.     

Management of mandibular angle fractures using the mandibular angle reduction forceps

The aim of this study was to determine whether or not the use of the mandibular angle reduction forceps decreases the incidence of post-operative complications. Forty-six patients, who presented with mandibular angle fractures with a displacement or dislocation, were randomly divided into two treatment groups. Both groups underwent an open reduction with a single upper border miniplate and screw fixation. For 23 patients, the mandibular angle reduction forceps was used to aid in fracture reduction, and for 23 patients, the reduction of the fracture was achieved using IMF. The post-reduction radiographs showed that the reduction forceps group had a higher proportion of precise anatomic alignment of fracture than those in the IMF group. In addition, the former group showed a lower rate of post-operative complications, as compared to the latter group. This study found that the use of the mandibular angle reduction forceps is an important factor for decreasing the incidence of post-surgical complication.     

Effect of platelet-rich plasma on bone regeneration in autogenous bone graft

In this study, we evaluated the effect of platelet-rich plasma (PRP) on bone regeneration in an autogenous bone graft in a canine model. The mandibular premolar teeth had been bilaterally extracted previously, and the ridges had been allowed to heal for 3 months. After this period, continuity resection was performed on both sides of the mandible. One defect (the PRP group) was reconstructed with the original particulate bone mixed with PRP. As a control, the contralateral defect (non-PRP group) was reconstructed with the original particulate bone alone. Biopsies after 6 weeks showed lower levels of bone formation in the PRP group than in the non-PRP group, and fluorescence microscopy revealed a delay in the remodelling of grafts loaded with PRP. These findings suggest that the addition of PRP does not appear to enhance new bone formation in autogenous bone grafts.     

Memory traces in dynamical systems

To perform nontrivial, real-time computations on a sensory input stream, biological systems must retain a short-term memory trace of their recent inputs. It has been proposed that generic high-dimensional dynamical systems could retain a memory trace for past inputs in their current state. This raises important questions about the fundamental limits of such memory traces and the properties required of dynamical systems to achieve these limits. We address these issues by applying Fisher information theory to dynamical systems driven by time-dependent signals corrupted by noise. We introduce the Fisher Memory Curve (FMC) as a measure of the signal-to-noise ratio (SNR) embedded in the dynamical state relative to the input SNR. The integrated FMC indicates the total memory capacity. We apply this theory to linear neuronal networks and show that the capacity of networks with normal connectivity matrices is exactly 1 and that of any network of N neurons is, at most, N. A nonnormal network achieving this bound is subject to stringent design constraints: It must have a hidden feedforward architecture that superlinearly amplifies its input for a time of order N, and the input connectivity must optimally match this architecture. The memory capacity of networks subject to saturating nonlinearities is further limited, and cannot exceed N. This limit can be realized by feedforward structures with divergent fan out that distributes the signal across neurons, thereby avoiding saturation. We illustrate the generality of the theory by showing that memory in fluid systems can be sustained by transient nonnormal amplification due to convective instability or the onset of turbulence.     

Exact subgrid interface correction schemes for elliptic interface problems

We introduce a nonconforming finite-element method for second order elliptic interface problems. Our approach applies to problems in which discontinuous coefficients and singular sources on the interface may give rise to jump discontinuities in either the solution or its normal derivative. Given a standard background mesh and an interface that passes between elements, the key idea is to construct a singular correction function that satisfies the prescribed jump conditions, providing accurate subgrid resolution of the discontinuities. Utilizing the closest point extension and an implicit interface representation by the signed distance function, an algorithm is established to construct the correction function. The result is a function that is supported only on the interface elements, represented by the regular basis functions, and bounded independently of the interface location with respect to the background mesh. In the particular case of a constant second-order coefficient, our regularization by a singular function is straightforward, and the resulting left-hand side is identical to that of a regular problem without introducing any instability. The influence of the regularization appears solely on the right-hand side, which simplifies the implementation. In the more general case of discontinuous second-order coefficients, a normalization is invoked which introduces a constraint equation on the interface. This results in a problem statement similar to that of a saddle-point problem. We employ two-level iteration as the solution strategy, which exhibits aspects similar to those of iterative preconditioning strategies.