Variable compensation technique for digital radiography of the chest

The authors describe a new technique, variable compensation (VC) radiography, for digital radiography of the chest. It permits retrospective adjustment of image display while maintaining improved mediastinal signal-to-noise ratio (S/N) from aggressive x-ray equalization. A fraction of a logarithmic image representing the profile of the beam intensity incident on the patient is subtracted from a logarithmic equalized image. VC images of a chest phantom were generated with various weightings of the beam-profile image. Edge artifacts were substantially reduced with a weighting of greater than 0.5 and eliminated with a weighting of 1.0. The S/N properties of VC images were measured with a series of plastic squares placed over various regions of the chest phantom. The S/N of the squares in the dense sub-diaphragm were improved twofold compared with the S/N on unequalized radiographs, whereas the S/N in the lung was reduced by 30%. Studies of a volunteer revealed the ability to render images with aggressive equalization (for improved mediastinal visualization) and images with the appearance of traditional chest radiographs.     

Infectious disease complications of simultaneous pancreas kidney transplantation

BACKGROUND: Although technical success rate of simultaneous pancreas kidney (SPK) transplantation in insulin-dependent diabetes mellitus (IDDM) patients with diabetic nephropathy has improved, morbidity remains high due to infection and rejection. The purpose of this study was to analyse infections encountered in our series of SPK transplants, using a restrictive antibiotic prophylaxis policy. METHODS: We reviewed all infectious diseases after 66 consecutive bladder-drained SPK transplantations in 64 IDDM patients with end-stage renal disease due to diabetic nephropathy. During follow-up, the perioperative antibiotic regimen was altered (from 5 days preemptive therapy with multiple drugs to 1 day prophylaxis with cefamandole), and long-term viral prophylaxis (high-dose aciclovir) was introduced. For post-operative urinary tract or opportunistic infection, no prophylaxis was given. RESULTS: Overall mean infection rate was 2.9 infections/ patient/year after a mean follow-up of 2.3 years. Surgical site infections (SSI) were seen in 30% of the patients, with Enterococci present in 47%. Logistic regression showed one day cefamandole prophylaxis to be associated with SSI, but there was no significant influence of SSI on either graft or patient survival. Forty-eight percent of all infections were lower urinary tract infections (UTI). There were 59 first UTIs (89%), probably related to long-term Foley catheter use, and 47 second UTIs (71%). Subsequent UTIs were not microbiologically related to first UTIs. Cytomegalovirus (10 patients) and other opportunistic agents did not cause mortality or graft loss. Five grafts were lost due to infection (SSI three times, post-transplant lymphoproliferative disease twice). Only one patient died because of infection (2%). CONCLUSIONS: Infectious diseases after SPK transplantation caused significant morbidity but did not influence either patient or graft survival. A change in prophylactic policy for both SSI as well as recurrent UTI, combined with earlier Foley removal, may lower incidences of these infections.      

Induction of tumor-specific T cell response by cognating tumor cells with foreign antigen-primed Th cells

Sufficient CD4+ T cell help is very important in generating specific cytotoxic T cell responses. The inadequate activation of tumor-specific Th cells leads to failure of antitumor immunity. In general, each individual consists of some primed Th cells responding to certain antigens. If these tumor non-specific pre-primed Th cells can provide sufficient help, the generation of tumor-specific T cells may be enhanced. In the present study, we tested this hypothesis by cognating and reactivating pre-primed ovalbumin (OVA)-specific Th cells with OVA- pulsed tumor cells which could simultaneously present both OVA and tumor-associated antigen on the same cell. We clearly demonstrated that immunization of OVA-sensitized mice with OVA-pulsed P388 cells, but not unpulsed P388 cells, led to the induction of P388-specific cytotoxicity and tumor resistance. Both CD4+ and CD8+ tumor-specific cytotoxic T cells were detected in vitro, but only CD8+ T cells played the major effector role in preventing the growth of challenged tumor in vivo. Taken together, our study demonstrated that the immunogenicity of tumor cells can be enhanced effectively by cognating pre-primed foreign antigen-specific Th cells with tumor cells. These findings have potential implications in developing methods to control tumor growth.      

(-),( )黄皮酰胺对鼠脑内 NMDA- 受体的影响

用［３Ｈ］ＭＫ８０１放射配体竟争结合法测定了（－），（＋）黄皮酰胺对大鼠前脑，海马，皮层等部位突触膜的ＮＭＤＡＲ的作用，以探讨其促智机制。同时用饱和实验分析ｐｏ给药１０ｄ后，小鼠脑内该受体密度的变化。结果表明：（－），（＋）黄皮酰胺对脑内各部位的ＮＭＤＡ受体均无特异亲和力。但（－）黄皮酰胺在体给药１０ｄ后能使小鼠脑内ＮＭＤＡ受体密度显著增高，并呈一定的量效关系。提示黄皮酰胺的药理作用有光学选择性；（－）黄皮酰胺增加脑内ＮＭＤＡ受体密度为其促智作用提供了重要理论依据。     

Hepatic metastasis detection: comparison of three CT contrast enhancement methods

A prospective, blinded comparison of three methods of hepatic contrast enhancement in computed tomography (CT) was conducted in 15 patients with colorectal carcinoma metastatic to the liver. Arterial portography (AP-CT) was performed with injection of contrast material into the superior mesenteric artery during CT. Delayed scanning (DS-CT) was performed 4 hours after intravascular administration of contrast material (mean dose, 280 mL). CT with an ethiodized oil emulsion (EOE-CT) was performed 1 hour after slow intravenous infusion of the emulsion. All patients underwent laparotomy following imaging studies. A lesion-by-lesion analysis of 56 metastases showed no significant differences in sensitivity (AP-CT, 77%; DS-CT, 83%; EOE-CT, 82%), but the false-positive rate for AP-CT was significantly higher than that for DS-CT (P less than .001) or EOE-CT (P less than .01). False-positive rates for EOE-CT and DS-CT were not significantly different. The predictive value of a positive test was 63% for AP-CT, 90% for DS-CT, and 81% for EOE-CT. AP-CT does not appear to be clinically useful for detection of hepatic metastases because of the high false-positive rate. No difference could be demonstrated between DS-CT and EOE-CT. DS-CT is a valuable method for hepatic contrast enhancement.     

Amebic liver abscess: diagnosis and treatment evaluation with MR imaging

Magnetic resonance images were obtained before and after treatment in 17 patients with 29 amebic liver abscesses. Pretreatment T1-weighted images showed a sharply circumscribed, heterogeneous, low-signal-intensity mass, devoid of normal hepatic tissue and corresponding to the abscess cavity as measured sonographically. T2-weighted images showed the abscess cavity as a hyperintense region and also showed a larger region of hyperintensity extending from the cavity margins to the liver surface, corresponding to edematous but morphologically normal liver tissue. After treatment, the abscess cavity became homogeneously hypointense on T1-weighted images, corresponding to liquefaction of the abscess center. With successful treatment, concentric rings corresponding to (a) an inner margin of inflamed granulation tissue, (b) bands of type I collagen, and (c) the outer margin of atrophic and/or mildly inflamed liver tissue became prominent on T1- and T2-weighted images. T2-weighted images showed rapid resolution of the perifocal hepatic edema.