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151.
A case of achalasia complicated by Mycobacterium fortuitum pulmonary infection and empyema is reported. This association has been documented in the medical literature. Possible mechanisms explaining this association are discussed. 相似文献
152.
153.
The NADPH-dependent reduction of chromium (VI), a known carcinogen, by
hepatic microsomes was very similar for all five humans examined, with an
apparent Km for chromate of 1.04-1.68 microM, and a Vmax of 10.4- 10.7
nmol/min/mg protein. Inhibitor studies indicate no role for cytochrome
P450s, but a prominent role for flavoproteins, which could include P450
reductase, flavin-containing mono-oxygenase and cytochrome b5. Relative to
anaerobic conditions, Cr(VI) reduction was inhibited only 26-37% by room
air, which indicates that human microsomal Cr(VI) reduction could still
proceed at significant rates, even in tissues with high O2 tensions.
Studies with lung microsomes from one human exhibited Vmax and Km values
that were two-thirds lower and 2.8-fold greater, respectively, than those
of hepatic microsomes from the same individual; other Cr(VI)-reducing
parameters were similar for lung and liver. Various forms of exogenous
iron, when present at 0.76-6.3 microM, markedly enhanced both liver and
lung microsomal rates and Vmax of Cr(VI) reduction, but did not
significantly alter the other Cr(VI)- reducing parameters (Km, effects of
O2 and inhibitors). These iron levels were 3.1- to 26-fold lower than the
initial Cr(VI) concentration, which suggests that iron is serving a
catalytic role. The ratio of human microsomal Cr(VI) reduction rates under
aerobic versus anaerobic conditions remained fairly constant, regardless of
iron concentration. Small increases in intracellular iron could therefore
lead to large increases in the rate and extent of microsomal Cr(VI)
reduction. Individuals that are simultaneously exposed to Cr(VI) and to
agents that increase intracellular iron could therefore be at potentially
greater risk for Cr(VI) toxicity and carcinogenicity.
相似文献
154.
155.
Data compression increases the number of images that can be stored on magnetic disks or tape and reduces the time required for transmission of images between stations. Two algorithms for data compression are compared in application to computed tomographic (CT) images. The first, an information-preserving algorithm combining differential and Huffman encoding, allows reconstruction of the original image. A second algorithm alters the image in a clinically acceptable manner. This second algorithm combines two processes: the suppression of data outside of the head or body and the combination of differential and Huffman encoding. Because the final image is not an exact copy, the second algorithm is information losing. Application of the information-preserving algorithm can double or triple the number of CT images that can be stored on hard disk or magnetic tape. This algorithm may also double or triple the speed with which images may be transmitted. The information-losing algorithm can increase storage or transmission speed by a factor of five. The computation time on this system is excessive, but dedicated hardware is available to allow efficient implementation. 相似文献
156.
Transient synovitis of the hip in children: role of US 总被引:7,自引:0,他引:7
Marchal GJ; Van Holsbeeck MT; Raes M; Favril AA; Verbeken EE; Casteels- Vandaele M; Baert AL; Lauweryns JM 《Radiology》1987,162(3):825-828
Transient synovitis of the hip remains a common diagnostic problem for the clinician. The physical signs are not pathognomonic of the condition, and the classic technical examinations are of little help. Therefore, the authors retrospectively studied the value of hip arthrosonography in 46 children with clinical symptoms suggesting pathologic hip conditions. In 20 of the 21 patients with a final diagnosis of transient synovitis, articular effusion was detected on ultrasound (US). Conventional radiography showed an increased medial joint space in only eight of these patients. Increased echogenicity of the articular fluid was found in both transient synovitis and septic arthritis. The high sensitivity of US in detecting intraarticular fluid was demonstrated by cadaver studies. 相似文献
157.
Regeneration of diabetic axons has delays in onset, rate and maturation. It is possible that microangiopathy of vasa nervorum, the vascular supply of the peripheral nerve, may render an unfavorable local environment for nerve regeneration. We examined local nerve blood flow proximal and distal to sciatic nerve transection in rats with long-term (8 month) experimental streptozotocin diabetes using laser Doppler flowmetry and microelectrode hydrogen clearance polarography. We then correlated these findings, using in vivo perfusion of an India ink preparation, by outlining the lumens of microvessels from unfixed nerve sections. There were no differences in baseline nerve blood flow between diabetic and nondiabetic uninjured nerves, and vessel number, density, and area were unaltered. After transection, there were greater rises in blood flow in proximal stumps of nondiabetic nerves than in diabetic animals associated with a higher number, density, and caliber of epineurial vessels. Hyperemia also developed in distal stumps of nondiabetic nerves but did not develop in diabetic nerves. In these stumps, diabetic rats had reduced vessel numbers and smaller mean endoneurial vessel areas. Failed or delayed upregulation of nerve blood flow after peripheral nerve injury in diabetes may create a relatively ischemic regenerative microenvironment. 相似文献
158.
Wallerian degeneration after cerebral infarction: evaluation with sequential MR imaging 总被引:14,自引:0,他引:14
The dynamic signal intensity changes at magnetic resonance (MR) imaging in active and chronic wallerian degeneration in the corticospinal tract were evaluated. Forty-three patients with wallerian degeneration seen on MR images after cerebral infarction were studied. When possible, patients with acute stroke were examined with MR imaging prospectively at the onset of symptoms and then at weekly intervals for several months. Focal infarction without distal axonal degeneration is demonstrated for the 1st month following onset of clinical symptoms. At 4 weeks, a well-defined band of hypointense signal appears on T2-weighted images in the topographic distribution of the corticospinal tract. After 10-14 weeks, the signal becomes permanently hyperintense. Over several years, accompanying ipsilateral brain stem shrinkage occurs. The dark signal intensity observed on T2-weighted images between 4 and 14 weeks is believed to result primarily from transitory increased lipid-protein ratio. 相似文献
159.
Goldberg HI; Grossman RI; Gomori JM; Asbury AK; Bilaniuk LT; Zimmerman RA 《Radiology》1986,158(1):157-161
Two men underwent high-resolution magnetic resonance (MR) imaging of the internal carotid artery (ICA) 12 and 16 days after spontaneous dissection of this vessel. One underwent follow-up MR imaging 7 weeks later. T1-weighted images were obtained in both cases, and T2-weighted images were obtained in one patient. In both cases, the MR findings corresponded to the angiographic abnormalities. On both the T1- and T2-weighted images, there was a hyperintense lesion expanding the wall and narrowing the lumen of the ICAs. Follow-up MR imaging showed complete resolution of the mural lesion. Axial images best demonstrated the anatomic and MR signal alterations. The hyperintensity of the lesion on both T1- and T2-weighted images indicated a short T1 and a long T2 as expected in a subacute hematoma. High-resolution MR imaging, therefore, can specifically demonstrate a thrombosed carotid dissection noninvasively at least as early as 12 days. The potential to diagnose carotid dissection in the acute phase using high-field-strength MR imaging and its importance for the prevention of embolic strokes are also discussed. 相似文献
160.