Evolution of the cranial computed tomography scan in child abuse

Computed tomography (CT) scans obtained at the time of clinical presentation have occasionally been reported to be normal in children with history and findings of significant abusive head injury. We have retrospectively observed abnormalities in "normal" scans of some similar children. We have also seen abnormalities develop on serial scanning. To determine how frequently these situations occur, we reviewed charts of 34 children with a final diagnosis of child abuse who also had cranial CT scans performed. Their CT scans were retrospectively reviewed by a pediatric radiologist. Eleven (11/34) CT scans had initially been interpreted as normal. Four (4/11) of these had been reinterpreted during the hospitalization as abnormal, affecting medical (1) and legal (3) outcome. Repeat scanning in three of the remaining seven resulted in surgical drainage of a subdural effusion (1) and affected legal outcome (2). Four of the seven initial scans felt normal throughout the hospitalizations were judged abnormal on retrospective review. This evaluation was confirmed in the two rescanned. Initial CT interpretation most often failed to appreciate changes in parenchymal density and small amounts of falcine or cortical subdural blood. Subsequent scans also showed evolving effusions and infarcts. Changes were noted in 1 1/2 to 5 days. The CT scan frequently shows subtle changes in the immediate posttrauma period. If the child does not recover promptly, subsequent scans frequently result in significant changes in clinical and legal management.     

Evidence that human cardiac allograft acceptance is associated with a decrease in donor-reactive helper T lymphocytes

We have reported that acute cardiac allograft rejection is associated with increased numbers of donor-reactive helper T lymphocytes (HTL) in the peripheral blood of patients. Further, increased frequencies of circulating donor-reactive HTL may predict allograft rejection episodes diagnosed by endomyocardial biopsy. The present study evaluates the relationship between donor-reactive HTL and allograft "acceptance" in cardiac transplant recipients bearing long-term allografts (> 1 year). Patients were categorized as either long-term acceptors or persistent rejecters based on the number of rejection episodes and the ability to withdraw steroid therapy. Limiting dilution analysis for IL-2-producing HTL was utilized, with cadaver donor splenocytes as a source of donor alloantigens. Donor-reactive HTL frequencies were determined from peripheral blood samples obtained before transplant, and at 1 month and 1 year after transplant. Individuals who accommodated their allografts and were withdrawn from steroid therapy had reduced numbers of donor-reactive HTL at 1 year after transplant as compared with earlier time points. Further, PBMC obtained from these individuals at 1 year after transplant responded weakly to donor alloantigens in a mixed lymphocyte response (MLR). This relationship between donor-reactive HTL and allograft accommodation was exemplified in a cardiac/liver transplant patient who was diagnosed with progressive multifocal leukoencephalopathy and removed from all immunosuppression. No subsequent rejection episodes were diagnosed. Donor-reactive HTL were not detectable and this individual failed to mount an MLR to donor alloantigens. However, a vigorous donor-reactive response was observed when MLR cultures were supplemented with exogenous IL-2. Therefore, nonresponsiveness to the allograft appeared to be due to a deficit in IL-2 production. In contrast, patients who experienced persistent rejection episodes and required continued steroid therapy maintained large numbers of donor-reactive HTL at 1 year after transplant. PBMC from these individuals responded vigorously to donor alloantigens in an MLR. Hence, monitoring donor-reactive HTL may identify individuals who have accommodated their graft and may tolerate a reduction in immunosuppression.     

Symptomatic subclavian steal syndrome four decades after operation for dysphagia lusoria

Congenital abnormalities of the aortic arch may lead to signs and symptoms of tracheal and esophageal obstruction secondary to a restrictive vascular ring. There are many case reports and monographs concerning the surgical management of dysphagia lusoria. This case provides the first example of long-term follow-up of surgical intervention for relief of dysphagia lusoria. A 45-year-old laborer presented with a several year history of episodic bilateral blindness and a more recent onset of "drop attacks." Notably this patient had presented at the age of 18 months with difficulty breathing and eating since birth. The patient also had frequent upper respiratory infections and episodes of pneumonia. Workup revealed a right-sided aortic arch with a left ligamentum arteriosum. When he was first seen in our clinic, history and physical examination revealed claudication and diminished pulses in the left upper extremity. Arteriography and duplex studies confirmed reversal of flow in the patient's left vertebral artery. The arteriogram demonstrated the presence of a right-sided aortic arch and descending aorta along with the proximal stump of the previously ligated left subclavian artery. He underwent left carotid to left axillary artery bypass for the treatment of symptomatic subclavian steal syndrome. His symptoms have resolved with return of antegrade vertebral flow and the presence of normal pulses in the left arm. Congenital aortic abnormalities that lead to tracheal and esophageal compromise are numerous and varied. Surgical management requires a thorough understanding of the person's anatomy and preoperative planning. The life expectancy of patients with dysphagia lusoria necessitates consideration of the long-term consequences of surgical intervention.     

The role of protein kinase in C ischemic/reperfused preconditioned isolated rat hearts

Protein kinase C (PKC) has been implicated in the preconditioning-induced cardiac protection in ischemic/reperfused myocardium. We studied the effect of PKC inhibition with calphostin C (25, 50, 100, 200, 400, and 800 nM), a potent and specific inhibitor of PKC, in isolated working nonpreconditioned and preconditioned ischemic/reperfused hearts. In the nonpreconditioned groups, all hearts underwent 30 min of normothermic global ischemia followed by 30 min of reperfusion. In the preconditioned groups, hearts were subjected to four cycles of ischemic preconditioning by using 5 min of ischemia followed by 10 min reperfusion, before the induction of 30 min ischemia and reperfusion. At low concentrations of calphostin C (25, 50, and 100 nM), the PKC inhibitor had no effect on the incidence or arrhythmias or postischemic cardiac function in the nonpreconditioned ischemic/reperfused groups. With 200 and 400 nM of calphostin C, a significant increase in postischemic function and a reduction in the incidence of arrhythmias were observed in the nonpreconditioned ischemic/reperfused groups. Increasing the concentration of calphostin C to 800 NM, the recovery of postischemic cardiac function was similar to that of the drug-free control group. In preconditioned hearts, lower concentrations (< 100 nM) of calphostin C did not change the response of the myocardium to ischemia and reperfusion in comparison to the preconditioned drug-free myocardium. Two hundred and 400 nM of the PKC inhibitor further reduced the incidence of ventricular fibrillation (VF) from the preconditioned drug-free value of 50% to 0 (p < 0.05) and 0 (p < 0.05), respectively, indicating that the combination of the two, preconditioning and calphostin C, affords significant additional protection. Increasing the concentration of calphostin C to 800 nM blocked the cardioprotective effect of preconditioning (100% incidence of VF). The recovery of cardiac function was similarly improved at calphostin C doses of 200 and 400 nM and was reduced at 800 nM (p < 0.05). With 200 and 400 nM of calphostin C, both cytosolic and particulate PKC activity were reduced by approximately 40 and 60%, respectively, in both preconditioned and preconditioned/ischemic/reperfused hearts. The highest concentration of calphostin C (800 nM) resulted in almost a complete inhibition of cytosolic (100%) and particulate (85%) PKC activity correlated with the abolition of preconditioning-induced cardiac protection. In conclusion, calphostin C protects the ischemic myocardium obtained from intact animals, provides significant additional protection to preconditioning at moderate doses, and blocks the protective effect of preconditioning at high concentrations. The dual effects of calphostin C appear to be strictly dose and "enzyme inhibition" related.     

Characterization of heat transfer along a silicon nanowire using thermoreflectance technique

We studied heat transfer along a silicon nanowire suspended between two thin-film heaters using a thermoreflectance imaging technique. The thermoreflectance imaging system achieved submicrometer spatial resolution and 0.1/spl deg/C temperature resolution using visible light. The temperature difference across the nanowire was measured, and then its thermal resistance was calculated. Knowing the dimension of the nanowire (115 nm in width and 3.9 /spl mu/m in length), we calculated the thermal conductivity of the sample, which is 46 W/mK. Thermal conductivity decreases with decreasing wire size. For a 115-nm-wide silicon nanowire, the thermal conductivity is only one-third of the bulk value. In addition, the transient response of the thin-film heaters was also examined using three-dimensional thermal models by the ANSYS program. The simulated thermal map matches well with the experimental thermoreflectance results.     

Distributed video coding in wireless sensor networks

This paper addresses the important aspect of compressing and transmitting video signals generated by wireless broadband networks while heeding the architectural demands imposed by these networks in terms of energy constraints as well as the channel uncertainty related to the wireless communication medium. Driven by the need to develop light, robust, energy-efficient, and low delay video delivery schemes, a distributed video coding based framework dubbed PRISM is introduced. PRISM addresses the wireless video sensor network requirements far more effectively than current state-of-the-art standards like MPEG. This paper focuses on the case of a single video camera and use it as a platform to describe the theoretical principles and practical aspects underlying distributed video coding.     

Fuzzy differential inclusions in atmospheric and medical cybernetics

Uncertainty management in dynamical systems is receiving attention in artificial intelligence, particularly in the fields of qualitative and model based reasoning. Fuzzy dynamical systems occupy a very important position in the class of uncertain systems. It is well established that the fuzzy dynamical systems represented by a set of fuzzy differential inclusions (FDI) are very convenient tools for modeling and simulation of various uncertain systems. In this paper, we discuss about the mathematical modeling of two very complex natural phenomena by means of FDIs. One of them belongs to the atmospheric cybernetics (the term has been used in a broad sense) of the genesis of a cyclonic storm (cyclogenesis), and the other belongs to the bio-medical cybernetics of the evolution of tumor in a human body. Since a discussion of the former already appears in a previous paper by the first author, here, we present very briefly a theoretical formalism of cyclone formation. On the other hand, we treat the latter system more elaborately. We solve the FDIs with the help of an algorithm developed in this paper to numerically simulate the mathematical models. From the simulation results thus obtained, we have drawn a number of interesting conclusions, which have been verified, and this vindicates the validity of our models.     

Characterization and densification studies on ThO2-UO2 pellets derived from ThO2 and U3O8 powders

ThO₂ containing around 2-3% ²³³UO₂ is the proposed fuel for the forthcoming Indian Advanced Heavy Water Reactor (AHWR). This fuel is prepared by powder metallurgy technique using ThO₂ and U₃O₈ powders as the starting material. The densification behaviour of the fuel was evaluated using a high temperature dilatometer in four different atmospheres Ar, Ar-8%H₂, CO₂ and air. Air was found to be the best medium for sintering among them. For Ar and Ar-8%H₂ atmospheres, the former gave a slightly higher densification. Thermogravimetric studies carried out on ThO₂-2%U₃O₈ granules in air showed a continuous decrease in weight up to 1500 °C. The effectiveness of U₃O₈ in enhancing the sintering of ThO₂ has been established.