PubMed Health⌕ Search

Biomedical subjects

J I Tchervenkov

Publications and source records attributed to J I Tchervenkov.

At least 37 records · Page 2Linked to original sources
PubMed1994

Small bowel transplantation. The effect of intraportal donor-specific transfusion 24 hours pretransplant and low-dose cyclosporine.

We tested the synergy of donor-specific transfusion (DST) and cyclosporine (CsA) in small bowel transplantation by comparing the systemic versus portal route of DST administration in a fully allogeneic rat model. The protocol is relevant to cadaveric transplantation by conditioning only 24 hr before allografting. A 1 ml intraportal DST day -1 and low-dose CsA significantly prolonged survival (MST 53.7 +/- 17.5 days) when compared with systemic DST day -1 and low-dose CsA (MST 18.4 +/- 5.6 days). This suggests that intraportal DST can be beneficial in cadaveric SBT, as only a 24-hr induction period is necessary. We speculate that antigen trapping in the liver and interaction of the DST with Kupffer cells is central to the portal DST effect.

Animals↗
PubMed1993

Bacterial translocation: a potential source for infection in acute pancreatitis.

Infections from enteric bacteria are a major cause of morbidity and mortality during acute pancreatitis (AP), but the pathways by which these organisms reach distant organs remains speculative. Experiments were conducted to determine if bacterial translocation could be a mechanism for infection during this disease. AP was induced in Lewis rats by i.v. infusion of caerulein (experiment I) or ligation of the head of the pancreas (experiment II). In a third experiment, rats were gavaged with 1 x 10(8) 14C-radiolabeled Escherichia coli and pancreatitis was induced with caerulein. Results in all three experiments showed that AP increased the number of viable bacteria recovered in peritoneal fluid, mesenteric lymph nodes (MLN), liver, lungs, and pancreas. Radionuclide counting indicated that AP enhanced the gut permeability to 14C E. coli. To estimate the impact of AP on the magnitude of translocation and on the ability of the host to clear bacteria, the nuclide and colony-forming units (CFU) ratios were calculated between animals with and without AP. Blood, peritoneal fluid, and MLN had the highest nuclide ratio. During AP, these tissues may be the principal routes for bacterial spreading from the gut lumen. Peritoneal fluid, pancreas, and lung were the tissues with the highest CFU ratio. Bacterial killing ability of these tissues is likely impaired during AP.

Acute Disease↗
PubMed1992

Effects of pre- and postengraftment donor-specific transfusions and cyclosporine on the enhancement of experimental allograft survival.

The tolerogenic effects of immediate pretransplant donor-specific transfusion (DST) with cyclosporine (CsA) have been well described. The purpose of this study was to determine if these effects could be improved upon by the administration of post-transplant DSTs. When added to a 29-day course of CsA, a single DST given 24 hr pretransplant improved graft survival compared to CsA alone (84.9 +/- 12.3 vs 40.0 +/- 8.8 days; P less than 0.05). The administration of an additional DST on post-transplant Days 7, 14, and 21 further improved this survival to 152 +/- 28 days, with 45% of grafts surviving greater than 200 days, until sacrifice. The donor specificity of this effect was demonstrated by the increased survival of second ACI grafts transplanted into Lewis recipients with existing "tolerant" ACI allografts (long-term survivors, or LTS); third-party Buffalo rat hearts transplanted into LTS rats in a similar manner were rejected normally. Loss of graft antigenicity was not seen, as retransplanted ACI hearts obtained from LTS Lewis rats were rejected in a first-order manner. From this we conclude that (1) the addition of multiple post-transplant DSTs improve the enhancement seen with preoperative DST and CsA, (2) loss of graft antigenicity does not contribute to this improved enhancement, and (3) this effect appears to be donor antigen specific.

Animals↗
PubMed1991

Increased gut permeability following burn trauma.

Twenty female Hartley guinea pigs, weighing 350 to 400 g, were given a 30% full-thickness burn injury. Gastrointestinal permeability was assessed before burn and on postburn days 1 through 3, 7, and 14 by administering 5 mL of an isotonic mixture of 8% lactulose and 1.15% L-rhamnose by gavage and measuring the urinary excretion for the next 7 hours. In normal guinea pigs, lactulose (molecular weight, 342d) is mostly absorbed by the paracellular route, whereas L-rhamnose (molecular weight, 164 d) is mostly absorbed by the transcellular route. Gut permeability to L-rhamnose did not increase after burn injury (211 micrograms before burn vs 230, 260, 180, 238, and 221 micrograms on days 1, 2, 3, 7, and 14, respectively, after burn). By contrast, gut permeability to lactulose increased significantly and was greatest in the first 48 hours after burn injury (60 micrograms before burn vs 380, 354, 203, 364, and 279 micrograms on days 1, 2, 3, 7, and 14, respectively, after burn). Gut permeability to low-molecular-weight compounds increases immediately after burn trauma, and this may be by a paracellular rather than transcellular mechanism.

Animals↗
PubMed1991

Selection criteria for liver transplant donors.

As the number of successful liver transplants has increased, the demand for donors has outpaced the supply. Approximately 25% of patients die awaiting an appropriate donor. Current criteria for assessing potential donors need to be closely examined. Fifty-six potential donors were evaluated by our transplant team by utilizing standard liver function tests (LFT's)-SGOT, SGPT, bilirubin. Additionally, a lidocaine metabolism test was performed by giving a 1 mg/kg IV dose of lidocaine over 1 minute and measuring the accumulation of the major metabolite monoethylglycinxylidide (MEGX) at 15 minutes by fluorescent polarization immunoassay (Abbott Diagnostics, Abbott Park, IL). Previous work has suggested that a MEGX less than 50 ng/mL is associated with initial non-function. Thirty-four donors were transplanted (group I) and all had initial function (all MEGX values were greater than 50). Twenty-two donors (39%) were judged unacceptable (group II) by our transplant team and by outside centers based upon one of the following criteria: II A) elevated LFT's--8, 11 B) donor age--5, II C) donor instability--4, II D) no available recipient--3, II E) miscellaneous--2. Standard LFT's were not statistically different in the donors used and in those not used when excluding category II A. Six of seven donors excluded in group I had acceptable MEGX values indicating they may have been transplantable. Ten of 12 patients excluded in groups II B-D had normal LFT's and nine of 12 had acceptable MEGX values indicating they may have been transplantable also. In this era of organ shortage, a reevaluation of donor selection criteria utilizing new tests like MEGX may be necessary to meet the increased need.

Adolescent↗
PubMed1991

Segmental orthotopic hepatic transplantation as a means to improve patient survival and diminish waiting-list mortality.

Pediatric liver transplantation continues to be limited by the availability of suitable liver donors, a factor that restricts programmatic development and ultimately contributes to death on the recipient waiting list. We report the application of segmental liver transplantation as a technique to address both these problems as well as improving the outcome of the child undergoing the transplant procedure. Since 1986, 37 children have undergone orthotopic liver transplantation. Twenty-three children have received whole-organ grafts; 81% survived. Of those receiving whole-organ grafts, 15% had arterial thrombotic complications and 23% required retransplantation. More importantly, 29% of those children listed for transplantation died while waiting for a donor organ to become available, with a mean interval of 1.7 months (range, 2 days to 4.5 months). Since July 1988, segmental liver transplantation has been a component of our therapeutic armamentarium, and of the past 20 liver recipients, 16 have received a left lobe segmental graft. The results of the segmental transplant series have shown striking improvements. First, no child has died while awaiting donor organ availability. Second, segmental liver recipient survival is equivalent to that of whole-organ graft recipients (81%). Third, hepatic arterial thrombosis, especially a problem in high-risk infant transplants, was reduced by this technique (5%). Retransplantation due to graft complications has not increased (21%). These data suggest a vital role for segmental liver transplantation not only as a remedial salvage procedure for the critically ill child, but also as a primary transplant option.

Adolescent↗
PubMed1991

Disseminated histoplasmosis in a renal transplant patient: a cause of renal failure several years following transplantation.

A 49-year-old man developed disseminated histoplasmosis 6 1/2 years after transplantation. The organism was initially present in the urine and in a tongue lesion. Treatment with itraconazole was instituted. However, there was further dissemination of the disease and worsening of renal function. Allograft biopsy showed extensive involvement with the organism. Amphotericin B was started, resulting in a rapid resolution of the disease. However, renal function deteriorated, leading to permanent hemodialysis.

Biopsy↗
PubMed1991

Enhancement of allograft survival by donor-specific transfusion one day prior to transplant. Importance of timing and specificity when DST is given with cyclosporine.

Donor-specific transfusion effects were studied in the ACI-to-Lewis rat heterotopic heart allograft model using cyclosporine immunosuppression. Low-dose CsA for 1 week plus a single fresh or stored DST given 1 day before allografting significantly prolonged graft survival over CsA therapy alone (median survival time 23.5 days vs. 10 days, P less than 0.01), but third-party transfusion did not (11.5 vs. 10 days, NS). When CsA was started at the time of DST and continued for 2 weeks, maximal graft enhancement was achieved after just one DST. DST/CsA was equally efficacious if given on any day before transplantation, provided CsA was started on the same day as the transfusion. However, pretransplant DST given without CsA shortened subsequent graft survival of day -1 DST/CsA treatment (14.5 days, n = 6, vs. 60 days for controls, n = 10; P less than 0.01). The addition of methylprednisolone to the DST/CsA protocol had no effect on graft survival (51 vs. 53 days, P = NS), but extending the period of postoperative CsA therapy for 4 weeks at reduced dose (2.5 mg/kg/day) significantly prolonged median survival (111 days, n = 11) and resulted in 45% permanent engraftment (greater than 120 days survival). CsA permits graft enhancement with a single DST as early as 1 day before grafting. This avoids the risk of sensitization from DSTs and can extend DST use to cadaveric graft recipients.

Animals↗
PubMed1991

Efficacy of induction therapy in cadaveric renal transplantation comparing rabbit antithymocyte serum and Minnesota antilymphoblast globulin.

From August 1986 to July 1989, 98 patients receiving primary cadaveric kidney transplants received either RATS (n = 50) or MALG (n = 48) during the induction phase of a quadruple immunosuppressive protocol. Patient groups were well matched. The duration of RATS and MALG treatment and the time of CyA induction were equivalent. Serum creatinine and rejection episodes up to 1 year were not statistically different. Hematologic side effects resulted in dose reduction of MALG in 42% of patients without adverse rejection results. In the RATS group, no dosage reductions were required. One-year patient survivals (96% to 100%), and 1-year graft survival (82% to 85%) were not significantly different in the 2 groups. Infectious complications were 30% higher in the MALG group and a significant factor in 2 deaths. Monitoring of lymphocyte subsets revealed insignificant differences in the percent of decrease of each cell population between MALG and RATS groups during induction.

Adult↗
PubMed1990

Variable infection risk following allogeneic blood transfusions.

These studies address infection risk of allogeneic transfusion in an untraumatized, nonseptic rodent model. A' Segaloff Cancer Institute rats served as blood donors and Lewis rats as recipients. Lewis rats' delayed-type hypersensitivity (DTH) response and their ability to clear subdermal Staphylococcus aureus abscesses and Candida albicans pyelonephritis were measured as tests of the effect of transfusions. The effect of pharmacological immunosuppression with either cortisone acetate or cyclosporine provided a "yardstick" to measure the magnitude of transfusion effects. Repeated transfusions at 1-week intervals diminished DTH response to recall antigens (keyhole limpet hemocyanin), but otherwise they showed no evidence of immunosuppression in these experiments. In contrast, we found that transfusions by themselves produced mild immunostimulation. Subcutaneous Staphylococcus abscesses were smaller in animals receiving transfusions. The magnitude of immunostimulation from one transfusion was sufficient to reverse the immunosuppressive effect of cyclosporine by about 50% in a Candida pyelonephritis infection. These studies suggest that blood transfusions have complex interactions with different components of the immune response. T-cell function is impaired by repeated transfusions (diminished DTH response), but other inflammatory responses are accentuated. This suggests that blood transfusions may harm immune response in traumatized animals by causing excessive complement activation or cytokine release.

Abscess↗