CD46 (membrane cofactor protein of complement, measles virus receptor): structural and functional divergence among species (review)

OBJECT: In this retrospective study, the authors analyzed the frequency, anatomical distribution, and appearance of traumatic brain lesions in 42 patients in a posttraumatic persistent vegetative state. METHODS: Cerebral magnetic resonance (MR) imaging was used to detect the number of lesions, which ranged from as few as five to as many as 19, with a mean of 11 lesions. In all 42 cases there was evidence on MR imaging of diffuse axonal injury, and injury to the corpus callosum was detected in all patients. The second most common area of diffuse axonal injury involved the dorsolateral aspect of the rostral brainstem (74% of patients). In addition, 65% of these patients exhibited white matter injury in the corona radiata and the frontal and temporal lobes. Lesions to the basal ganglia or thalamus were seen in 52% and 40% of patients, respectively. Magnetic resonance imaging showed some evidence of cortical contusion in 48% of patients in this study; the frontal and temporal lobes were most frequently involved. Injury to the parahippocampal gyrus was detected in 45% of patients; in this subgroup there was an 80% incidence of contralateral peduncular lesions in the midbrain. The most common pattern of injury (74% in this series) was the combination of focal lesions of the corpus callosum and the dorsolateral brainstem. In patients with no evidence of diffuse axonal injury in the upper brainstem (26% in this series), callosal lesions were most often associated with basal ganglia lesions. Lesions of the corona radiata and lobar white matter were equally distributed in patients with or without dorsolateral brainstem injury. Moreover, cortical contusions and thalamic, parahippocampal, and cerebral peduncular lesions were also similarly distributed in both groups. CONCLUSIONS: The data indicate that diffuse axonal injury may be the major form of primary brain damage in the posttraumatic persistent vegetative state. In addition, the authors demonstrated in this study that MR imaging, in conjunction with a precise clinical correlation, may provide useful supportive information for the accurate diagnosis of a persistent vegetative state after traumatic brain injury.     

Renal gunshot wounds: methods of salvage and reconstruction

Over the past 14 years, 2079 patients have been seen at our institution with renal trauma. Of these, 84 sustained gunshot wounds (81 unilateral, 3 bilateral; a total of 87 renal units). We evaluated this group to characterize the nature of their injuries and establish a methodology for renal salvage and reconstruction. Preoperative radiographic staging was performed with excretory urography (IVP) or computed tomographic (CT) scanning. The injuries were classified into five categories: 16 contusions (18.4%), 12 minor lacerations (13.8%), 44 major lacerations (50.5%), six vascular injuries (6.9%), and nine combination laceration and vascular injury (10.3%). Most patients had multiple organ injuries, with 79 requiring associated surgical procedures (94%). The mean injury Severity Score (ISS) was 26.7 (range, 4-59). Based on radiographic and clinical staging criteria, 69 renal injuries were surgically explored (79.3%), and 12 patients underwent nephrectomy (13.8%). Forty-six renal units were reconstructed (66.6%) by various methods, including renorrhaphy, omental pedical flaps, mesh or peritoneal patch grafts, partial nephrectomy, and vascular repair. Overall, 75 renal units were salvaged (86.2%). Early renal vascular control was achieved in all patients who underwent renal exploration. Follow-up functional studies were done in 24 (28.5%): none had delayed nephrectomy or postinjury hypertension. Overall, 79 patients survived (94%); however, mortality was not related to renal injury. These findings suggest that aggressive radiographic staging coupled with early vascular control and careful selection of reconstructive techniques can ensure a high renal salvage rate in patients with renal gunshot injuries.     

An efficient method of FIR filtering based on impulse responserounding

A new method of implementing efficient FIR filters is presented. It involves approximation of an equiripple FIR by a rounding operation and application of the derived impulse response by a simple recursive equation. The technique is extremely efficient for lowpass, highpass, bandpass, and bandstop filters with sharp transitions and low edge frequencies     

Expression of matrix metalloproteinases and their inhibitors in aneurysms and normal aorta

BACKGROUND: Abdominal aortic aneurysms (AAAs) are characterized by degradation of collagen and elastin resulting from increases in matrix metalloproteinase (MMP) activity. Previous authors have identified isolated increases in expression of specific MMPs in AAAs, but none have compared relative levels of expression of particular MMPs to one another or to those of their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). This study proposes to quantify relative mRNA levels for interstitial collagenase (MMP-1), 72 kd type IV collagenase (MMP-2), 92 kd type IV collagenase (MMP-9), TIMP-1, and TIMP-2 in normal aorta (NA) and AAA to provide insight as to the relative importance of each in aneurysm formation. METHODS: Competitive polymerase chain reactions (PCRs) with gene-specific external standards and cDNA derived from AAAs (n = 8; mean age, 67.4 years) and NA (n = 5; mean age, 40.6 years) were used to quantify mRNA levels. Results were normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels, determined by means of competitive PCR, and compared by means of Mann-Whitney statistics. RESULTS: Significant increases in MMP mRNA expression in AAA over NA were observed for MMP-1 (3.64 versus 0.3, p = 0.007), MMP-9 (78.03 versus 3.35, p = 0.003), TIMP-1 (835.32 versus 477.2, p = 0.027), and TIMP-2 (18.09 versus 4.14, p = 0.003). The ratio of MMP to TIMP mRNA levels was higher in AAA than NA (0.135 versus 0.045, p = 0.018). CONCLUSIONS: Increases in expression of MMP-1, MMP-9, and MMP/TIMP ratios may result in increased proteolysis and matrix degradation, which characterize AAAs. MMP-9 appears to be the predominant metalloproteinase expressed in AAA, because its mRNA levels were more than 20 times and 2 times higher than those of MMP-1 and MMP-2, respectively. TIMP-1 mRNA levels were in molar excess to those of any of the metalloproteinases studied.     

Systemic aluminum toxicity: effects on bone, hematopoietic tissue, and kidney

Although the full mechanisms are not yet elucidated, research into the mechanism of toxicity of aluminum (Al) on bone formation and remodeling and on hematopoietic tissue is ongoing. In contrast little information exists on the interactive effects of systemic Al and the kidney. In bone, both clinically and experimentally, high doses of Al inhibit remodeling, slowing both osteoblast and osteoclast activities and producing osteomalacia and adynamic bone disease. In contrast, while very low levels of Al are mitogenic in bones of experimental animals, the effect of low levels of Al in humans is unknown. Aluminum has been shown to have its mitogenic action at the osteoblast, but whether the effect on resorption is viz osteoblast-directed changes in osteoclast activity has not yet been determined. Parathyroid hormone (PTH) levels are disrupted by Al in humans and animals. Whether altered PTH levels play a major or even a minor role in Al-dependent osteotoxicity requires clarification. In hematopoietic tissue, Al causes a microcytic anemia, not reversible by iron. Friend leukemia cells treated with Al have been reported to accumulate excess iron, without incorporating it into ferritin or heme. It is not yet known which steps in iron metabolism are disrupted by Al, if they involve a single mechanism of action, or even if this disruption in iron metabolism accounts for the anemia seen in Al toxicosis. In kidney, research is needed to evaluate Al nephrotoxicity; there are almost no studies in this area. Furthermore, research is needed to evaluate mechanisms of renal Al excretion, presently shown by one study to occur at the distal tubule. Such studies might well throw light on whether Al plays a role in aggravating renal insufficiency, or whether the role of the kidney in Al toxicosis is limited to the causative effect of renal compromise on Al accumulation. In summary, while a number of mechanisms have been proposed for the toxic action of Al, no single mechanism emerges to explain these diverse effects of systemic Al. Recommendations for future research are presented and summarized in Table 1.     

A comparison of leaf-spring with aircushion trailer suspensions in the transport environment

Packaging engineers need to be able to accurately determine the forces present in the shipping environment in order to protect packaged goods. The purpose of this study was to determine the vertical vibration levels measured in three separate truck-trailer suspension systems; conventional leaf-spring, conventional air-ride and damaged air-ride. The main conclusion reached in this study is that the air-ride suspension when maintained gives lower power density (PD) levels on all road surfaces studied. A damaged air-ride suspension and leaf-spring suspension are very similar in response frequencies, although the damaged air-ride produces higher vibration levels at lower frequencies.     

Asbestos-related pericardial thickening detected by magnetic resonance imaging

Magnetic resonance imaging was performed in four male asbestos workers in whom the chest radiograph revealed pleural but not pulmonary or pericardial disease. Patients underwent thoracic multislice spin echo imaging, with measurement of left and right ventricular volumes at end-diastole and end-systole, and a study of the flow in the superior vena cava as an indirect measure to the filling of the right ventricle. Patients also underwent respiratory function tests and high-resolution computed tomography (HRCT). Magnetic resonance, but not HRCT, showed pericardial thickening in two patients. Magnetic resonance demonstrated reduced diastolic flow in the superior vena cava in one patient, reflecting impaired right ventricular filling. All other magnetic resonance measurements of cardiac function were normal. HRCT demonstrated mild asbestosis in three patients in which neither the chest radiograph nor magnetic resonance showed signs of parenchymal disease, and pericardiac calcification without thickening in one patient. It is concluded that magnetic resonance is superior to HRCT in identifying pericardial thickening, but that HRCT is superior to magnetic resonance in identifying asbestos-related pleural and pulmonary disease.     

Response of peripheral nerve to cyclic compression in a laboratory rat model

Repetitive cyclic loading of a nerve has been proposed as a pathogenic factor in the development of occupational compression neuropathies. Little is known about the basic response of peripheral nerve to cyclic compression. We investigated the hypothesis that cyclic compression is more detrimental to nerve function than constant compression. We measured the amplitudes and velocities of distally evoked action potentials in the presence of constant or cyclic compression of the tibial nerve in rats. Seven groups were subjected to constant or cyclic compression for 6 h by a computer controlled, hydraulically activated compression chamber. Nerves were compressed with 0 (control group), 30, 60, or 90 mm Hg of constant pressure or 0-30, 20-50, or 30-60 mm Hg of cyclic compression for approximately 20,000 compression cycles. Action potentials were recorded every 15 min. The effects of cyclic compression on nerve conduction were equivalent to the effects of constant compression at the average applied pressure. Cyclic loading itself does not appear to be an important pathogenic factor in the development of nerve conduction block.