Immunogenicity of rat renal allograft nephron components in vivo. Lack of correlation between MHC expression and immunogenic potential

Cultured rat nephron components--i.e., tubular cells, glomerular mesangial cells, and glomerular epithelial cells--were compared with cultured rat heart endothelial cells for their in vivo immunogenicity using the primed rejection assay (PRA). Gamma-interferon (gIFN) was used to regulate the class I and class II MHC antigen expression of the cells tested. The heart endothelial cells proved to be the only cell type capable of inducing a maximal rejection response in the native state. This was achieved with a cell number of 10(6) when the survival of a subsequent heart allograft from a relevant donor was reduced from 5 to 3 days. All kidney nephron components proved to be immunogenic in PRA but to a far lesser extent than the endothelial cells. A reduction of graft survival from 5 to 4 days was achieved with a cell number of 10(6) cells, and no immunogenic effect (with the exception of mesangial cells contaminated by a small number of macrophages) was observed in smaller cell numbers. The gIFN-treated endothelial cells were more potent than untreated endothelial cells. They reduced the graft survival to 4 days with a cell number of 10(3) and caused a maximal reduction of the survival to 3 days with a cell number of 10(5). The nephron components failed to increase their immunogenicity after 3-day gIFN treatment, regardless of a high increase in their class I and class II expression rates. The study suggests that, in contrast to the endothelial cells, none of the nephron components are able to act as an antigen-presenting cell on their own.     

Lack of correlation between femoral neck anteversion and acetabular orientation. Radiography and computed tomography in cadavers and in vivo

Radiography and computed tomography measurements were made of femoral neck anteversion, femoral head cartilage distribution, and the orientation of the acetabulum. The measurements were made in elderly cadaver femurs and in patients. They failed to establish any correlation between the femoral neck anteversion and the orientation of the articulating surface of the femoral head, nor between the femoral neck anteversion and the angles of the acetabulum.     

In vivo and ex vivo magnetic resonance imaging evaluation of early disc degeneration with histopathologic correlation

The in vivo and ex vivo microanatomic appearance of early disc degeneration were identified by magnetic resonance imaging and correlated with their respective histopathologic findings. Five cadaver spines (18 discs) and 25 patient studies (122 discs) all imaged at 1.5 Tesla were studied. Two signs of early degenerative disc disease were found: infolding and the central dot. Infolding of the central fibers of the outer annulus coalesced into a central dot of low signal intensity that was seen on both the ex vivo and in vivo images. Infolding was seen 29 of 122 times, and the central dot was observed 15 to 122 times on the in vivo images. A later form of degenerative disc disease was identified as a separation of the nucleus pulposus from the hyaline cartilage end-plate. This separation was seen as a linear area of either low or high signal intensity on the ex vivo images but only as a band of high signal intensity on the in vivo spin-echo 2,500-msec/80-msec images. Only 7 of 122 in vivo discs showed this separation. Internal herniation of nucleus pulposus into the outer annulus was seen only on the ex vivo images. Early degenerative disc disease may exist before there is loss of disc height or signal intensity on the long time-to-repetition (TR)/time-to-echo (TE) magnetic resonance images.     

Lack of correlation between activated clotting time and plasma heparin during cardiopulmonary bypass.

The activated clotting time (ACT) with a Hemochron system for determining heparin requirements during cardiopulmonary bypass surgery, (CPB) accompanied by hemodilution and hypothermia was evaluated using plasma heparin levels as a standard. In 28 patients who were administered a standard heparin regimen (300 units/kg prebypass, 8000 units in the pump prime and 100 units/kg hourly during CPB) mean prebypass plasma heparin was 4 units/ml, and ACT was 493 seconds. During CPB mean plasma heparin decreased significantly (p < 0.001) to 3.1 units/ml, whereas mean ACT increased significantly (p < 0.001) to 674 seconds. The mean protamine requirement predicted from ACT was significantly higher (43%) than predicted from plasma heparin levels or actual protamine administered. The ACT neither accurately reflected plasma heparin during CPB nor predicted protamine requirements. The fixed-dose regimen employed, however, prevented both intraoperative thrombosis, assessed clinically in all patients, and clotting on six arterial line filters, as determined by scanning EM, despite wide variations in ACT and plasma heparin levels during surgery.     

Lack of evidence for natural cytotoxicity deficiency against human ex vivo tumour cells in allograft recipients

Background. Allograft recipients, who have a high risk of developing malignancies, are deficient in natural killer cells which mediate natural cytotoxicity against tumour cells. We evaluated the relevance of NK deficiency in transplant patients with regard to the natural lysis of human tumour cells. Methods. Target cells were ex vivo tumour cells, obtained from solid tumours from kidney transplant patients and non-immunocompromised patients. Peripheral blood was extracted from kidney recipients and from normal controls. Mononuclear cells were separated after anti-CD3 and anti-TCR immunostaining to obtain NK and T cell subsets. LAK cells were obtained by in vitro IL2-activation. For each tumour, natural cytotoxicity assays were performed to compare effector cells from a kidney recipient with those from a normal control. Twenty-seven solid tumours, either allogenic or syngenic, were analysed, mainly consisting of renal, colon, and skin carcinomas. Results. Natural cytotoxicity assays on K562 targets confirmed the expected NK deficiency in the kidney recipients. However, the NK and LAK cells from the kidney recipients did not kill a smaller number of tumour target cells than the controls, whatever the tumour type, under both the syngenic and allogenic conditions. Conclusions. We conclude that natural cytotoxicity against human tumour cells cannot be extrapolated from the cytotoxicity assays with established cell lines, and that natural lysis of ex vivo human tumour cells is not impaired in transplant patients.     

Renal hypothermia: in vivo and ex vivo

Temporary occlusion of the renal artery may be necessary for operations to remove renal calculi in situ, such as partial nephrectomy, nephrolithotomy, and extended pyelolithotomy. Performance of these operations requires an understanding of renal responses to warm ischemia and available methods of protecting the kidney in situ when the period of arterial occlusion exceeds that which may be safely tolerated. Methods of extracorporeal renal preservation are also reviewed because autotransplantation and bench surgery may occasionally be employed to treat patients with renal calculous disease.     

Lack of correlation between different measurements of proprioception in the knee

Current methods of measurement of proprioceptive function depend on the ability to detect passive movement (kinaesthesia) or the awareness of joint position (joint position sense, JPS). However, reports of proprioceptive function in healthy and pathological joints are quite variable, which may be due to the different methods used. We have compared the validity of several frequently used methods to quantify proprioception. Thirty healthy subjects aged between 24 and 72 years underwent five established tests of proprioception. Two tests were used for the measurement of kinaesthesia (KT1 and KT2). Three tests were used for the measurement of JPS, a passive reproduction test (JPS1), a relative reproduction test (JPS2) and a visual estimation test (JPS3). There was no correlation between the tests for kinaesthesia and JPS or between the different JPS tests. There was, however, a significant correlation between the tests for kinaesthesia (r = 0.86). We conclude therefore that a subject with a given result in one test will not automatically obtain a similar result in another test for proprioception. Since they describe different functional proprioceptive attributes, proprioceptive ability cannot be inferred from independent tests of either kinaesthesia or JPS.     

Lack of correlation between splenic and marrow hematopoiesis following irradiation or irradiation and transplantation in mice.

Differences were seen in the relative importance of spleen and marrow in early erythroid regeneration of lethally irradiated mice given spleen or marrow cell transplants compared with that in sublethally irradiated mice with surviving endogenous hematopoietic cells. Radioactive iron uptake was predominantly in the spleen of mice with transplants and in the marrow of endogenously recovering mice. Visable spleen colony counts increased from day 4 to day 7 and plateaued through day 10 in the transplant system, but shoed a small abortive rise with a 5-day peak, followed by a steady increase from days 6 to 10 in the endogenous system. Comparisons of peroxidase-positive cells (granulocytes) in the marrow of femurs and humeri and iron uptake in marrow and spleen suggested that repopulation of the marrow and spleen were independent, while that of different areas of the marrow was interrelated. The interrelationship of the rate of marrow regeneration was closer in the endogenous than in the transplant system.     

Modulation of the antigraft response by preimmunization. Lack of correlation between regulatory events and graft survival

Using two H-2 congeneic mouse strain combinations, the effect of donor specific i.v. preimmunizations with allogeneic spleen cells was studied. Parameters analyzed were survival time of the subsequent skin graft, graft-induced delayed-type hypersensitivity (DTH) reactions, and humoral immune responses evoked by immunization and grafting. Depending on the dose of allogeneic cells used for preimmunization, a suppression of the DTH response was observed, commonly accompanied by a similarly dose-dependent antibody formation that was inversely related to the DTH response. Neither DTH reactivity nor the antibody response were correlated in this system with the survival time of the skin graft. The only modulation of the survival time to be observed was an accelerated rejection of the graft caused by nonirradiated, as compared with irradiated, donor spleen cells. The data are discussed with regard to the clinically observed effect of blood transfusions on the survival of renal transplants and the relationship between DTH and graft rejection.     

Lack of correlation between decreased chemotaxis and susceptibility to infection in burned rats

This study examined the relationship between chemotaxis and susceptibility to infection. Rats were subjected to a 30% BSA burn to the dorsum of the back and resuscitated. Rats with burns from 1 to 11 days old were injected with varying inocula of S. aureus into nonburned skin. Animals with burns more than 6 days old had significantly decreased PMN chemotaxis into the inoculation site but had no increase in susceptibility to infection. This lack of correlation between PMN chemotaxis and susceptibility to infection suggests that PMN motility is not the dependent factor in resistance to infection from S. aureus in this burn model.     

Lack of correlation between neuronal hyperexcitability and electrocorticographic responsiveness in epileptogenic human neocortex

OBJECT: The purpose of this study was to determine whether intrinsic neuronal properties and synaptic responses differed between interictally active and inactive tissue removed in neocortical resections from patients undergoing surgical treatment for epilepsy. METHODS: Whole-cell patch recordings were performed in layer 2 or 3 and layer 5 pyramidal cells in neocortical slices obtained from tissue surgically removed from patients for the treatment of medically intractable seizures. Synaptic responses to stimulation at the layer 6-white matter border were used to classify cells as nonbursting if they responded with only a single action potential for all above-threshold stimuli (80%). These responses were usually followed by biphasic inhibitory postsynaptic potentials (IPSPs). Cells were classified as bursting if they fired at least three action potentials in response to synaptic stimulation (20%). These cells typically showed no IPSPs and responded in either an all-or-nothing or graded fashion. Approximately twice as many cells at layer 2 or 3 (29%) than cells at layer 5 (14%) fired synaptic bursts. Synaptic bursting was not associated with an alteration in a cell's response properties to gamma-aminobutyric acid. It was notable that, in tissue samples determined by electrocorticography (ECoG) to be either interictally active or not active, the proportion of cells that burst was exactly the same in both groups (24%). We found no cells with intrinsic burst firing. CONCLUSIONS: We conclude that synaptic bursting was characteristic of a small proportion of cells from epileptic tissue; however, this did not correlate with interictal spikes on ECoG.     

Lack of correlation between urea kinetic indices and clinical outcomes in CAPD patients

We examined the predictive value of urea kinetics for patient outcomes in CAPD by measuring dialysis index (DI; a means of quantifying CAPD dose using urea kinetics), KT/V and normalized protein catabolic rate (PCRN) on 222 occasions in 76 new patients at the time of starting CAPD and at subsequent six month intervals. We investigated how these indices altered with time and in relation to each other, and how they correlated with a wide range of subsequent patient outcomes. DI, KT/V and PCRN all tended to decrease with time on CAPD (P less than 0.0004, less than 0.0001 and 0.0005, respectively). DI and KT/V were highly correlated with each other (r = 0.89, P less than 0.0001) and both correlated with PCRN (r = 0.57, P less than 0.0001 and r = 0.60, P less than 0.0001, respectively). DI and KT/V both correlated inversely with subsequent values for serum creatinine (P less than 0.0001), urea (P less than 0.0002), potassium (P less than 0.02) and phosphate (P less than 0.002), and directly with bicarbonate (P less than 0.0001). PCRN correlated inversely with serum creatinine (P less than 0.0002) and directly with urea (P less than 0.0001) and with the number of blood transfusions received (P less than 0.03). None of these indices correlated with levels of hemoglobin, PTH, alkaline phosphatase or albumin, or with nerve conduction velocity or any other subsequent clinical outcomes including death, technique failure, hospital days, peritonitis rate and subjective indices of fatigue, pruritus and insomnia. We conclude that the urea kinetic model is predictive of some biochemical outcomes but not of clinical outcomes in CAPD patients.     

Aortic Slimgraft: ex vivo and in vivo study

In this article we describe a method for assembling an endovascular graft within the aorta with a graft and then a stent introduced sequentially over a guidewire as separate components. In the ex vivo study, an endovascular graft that was 25 mm in diameter was introduced through a 9F introducer. In the in vivo study, smaller endovascular grafts were placed in the aortas of four healthy pigs and five pigs with aortic aneurysms. Our data suggest that this very low profile system may have significant clinical implications because it converts aortic repair into a percutaneous procedure.     

Allo-tolerance and allorejection responses ex vivo

Spleen cells from fully immune competent mice show different intracellular STAT responses to alloantigen. Cells from mice primed to accept the alloantigen have low STAT 6 and fragmented STAT 4, compared to cells from mice primed to reject the same alloantigen.