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Biomedical subjects

D C Cronin

Publications and source records attributed to D C Cronin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Complications in 100 living-liver donors.

OBJECTIVE: A review of 100 living-liver donors was performed to evaluate the perisurgical complications of the procedure and thus to help quantify the risks to the donor. SUMMARY BACKGROUND DATA: Despite the advantages of living-donor liver transplantation (LDLT), the procedure has received criticism for the risk it imposes on healthy persons. A paucity of data exists regarding the complications and relative safety of the procedure. METHODS: One hundred LDLTs performed between November 1989 and November 1996 were reviewed. Donor data were obtained by chart review, anesthesia records, and the computerized hospital data base. Patient variables were compared by Fisher's exact test and the Student's t test. RESULTS: There were 57 women and 43 men with a median age of 29. Donors were divided into two groups: group A (first 50 donors), and group B (last 50 donors). There were 91 left lateral segments and 9 left lobes. There were no deaths. Fourteen major complications occurred in 13 patients; 9 occurred in group A and 5 in group B. Biliary complications consisted of five bile duct injuries (group A = 4, group B = 1) and two cut edge bile leaks. Complications were more common in left lobe resections (55%) than in left lateral segment grafts (10%). Minor complications occurred in 20% of patients. A significant reduction in overall complications (major and minor) was observed between the groups (group A, n = 24 [45%] vs. group B, n = 10 [20%]). In addition, surgical time and hospital stay were both significantly reduced. CONCLUSIONS: Although the procedure is safe, many LDLT donors have a perisurgical complication. Surgical experience and technical modifications have resulted in a significant reduction in these complications, however. To minimize the risks for these healthy donors, LDLT should be performed at institutions with extensive experience.

Adult↗
PubMed1996

Comparison of pancreas transplantation with portal venous and enteric exocrine drainage to the standard technique utilizing bladder drainage of exocrine secretions.

Although bladder drainage of pancreatic exocrine secretions has been reported to decrease morbidity and improve pancreas allograft survival, significant complications remain associated with this technique. Furthermore, this technique requires systemic venous drainage of pancreas allografts. Evidence suggests that portal venous drainage of pancreas grafts prevents hyperinsulinemia and improves lipoprotein composition. This report documents our initial experience with portal venous and enteric exocrine drainage of pancreas allografts (portal/enteric technique) and compares it with the standard technique of systemic venous and bladder exocrine drainage (systemic/bladder technique). Patient and allograft survival, as well as allograft function, were comparable for the two procedures. There were no significant technical complications in this pilot series. Enteric exocrine drainage was associated with a significant reduction in the incidence of acidosis and dehydration when compared with bladder drainage (P<0.005). The portal/enteric technique also avoided reoperation for enteric conversion, as was required by 33% of patients in the systemic/bladder group. The incidence and outcome of allograft rejection were similar for the two techniques. These data suggest that combined pancreas/kidney transplantation with portal venous and enteric exocrine drainage is safe and results in outcomes similar to the standard technique, while eliminating many complications of bladder drainage. These findings should encourage additional studies to determine the consequences of portal venous drainage.

Drainage↗
PubMed1996

Use of polytetrafluoroethylene patch for temporary wound closure after pediatric liver transplantation.

Despite numerous options for pediatric transplantation, closure of the abdominal wall after liver transplantation is occasionally difficult, resulting in increased abdominal pressure and possible vascular compromise. Since 1990, we have utilized a 2-mm thick sheet of polytetrafluoroethylene (PTFE) to overcome this situation in 21 transplants for 17 patients. The median age was 0.9 months. Ten of the 21 transplants utilized full-size grafts. The donor to recipient weight ratio was 1.7+/-1.2. Cadaveric left lateral segments were used in 8 of 21 transplants (weight ratio, 7.4+/-5.9), living donor left lateral segments were used in 3 of 21 transplants (weight ratio, 13.2+/-6.7). We were able to remove 14 of 21 patches with one additional operation, whereas 4/21 patches required two operations and 3/21 required three operations. Reoperations identified two cases of hepatic artery thrombosis not previously identified by duplex ultrasonography. There were no technical problems or adverse effects associated with the use of the PTFE patch. After patch removal, the fascia was closed with a nonabsorbable suture and the skin was allowed to close by secondary intention. There were no wound infections, portal vein thrombosis, or fluid and electrolyte abnormalities. PTFE is a safe, temporary alternative to primary wound closure in liver transplantation when the size of the graft or intestinal and graft edema does not allow conventional closure of the abdomen. Infectious, fluid/electrolyte, or ventilatory complications were not noted. The necessity of a second-look operation is useful in assessing the graft and vascular patency. The majority of patches can be removed within the first postoperative week.

Child, Preschool↗
PubMed1995

IL-4-producing CD8+ T cell clones can provide B cell help.

Interactions between CD4+ T cells and B cells are mediated by both soluble factors and cell surface molecules. The Ag-independent interaction between the CD40 ligand, expressed on activated T cells, and its CD40 receptor, expressed on B cells, enhances B cell proliferation in response to IL-4 stimulation. The expression of the CD40 ligand is induced on CD4+ T cells by stimulation with Ag-pulsed APC or mitogens. Here, we show that at least some IL-4-producing murine CD8+ T cell clones can be induced to express the CD40 ligand when stimulated with anti-CD3 mAb. Additionally, such activated CD8+ IL-4-producing clones potentiate the proliferative response of small resting B cells to IL-4 and induce Ig secretion by small resting B cells to IL-4 and IL-5. Proliferation of small resting B cells cultured with IL-4 in the presence of activated IL-4-producing CD8+ murine T cell clones appeared to be mediated by the expression of the CD40 ligand on the T cell because an anti-CD40 ligand mAb inhibited this proliferative response. A conventional murine CD8+ CTL clone, which did not produce IL-4 or express CD40 ligand upon activation, did not potentiate proliferation of small resting B cells exposed to IL-4. Thus, under some circumstances, CD8+ T cells that are able to express CD40 ligand may be able to provide B cell help.

Animals↗
PubMed1995

Regulation of T lymphocyte subsets.

Patterns of cytokine secretion and functional differences distinguish T lymphocyte subsets. T lymphocyte subsets are also regulated differentially. Most established CD8+ lymphocyte clones secrete gamma-interferon (IFN-gamma) but not interleukin 2 (IL-2) or IL-4. Using murine T cells which express a transgenic, antigen-specific alpha/beta T cell receptor (TCR) specific for L(d) class I major histocompatibility complex antigen, we have found that CD8+ lymphocytes can be divided into functional subsets. Freshly isolated CD8+ T cells are not cytolytic, do not proliferate and do not proliferate and do not secrete cytokines. Stimulation of TCR alone does not induce cytokine secretion, but cells become responsive to exogenous IL-2 or IL-4. Stimulation of CD28 together with TCR induces secretion of IL-2 and IFN-gamma, and cells proliferate without exogenous cytokines. Proliferation is necessary for the development of cytolytic activity. If IL-4 is present during initial stimulation, IL-4 is secreted following restimulation. Upon stimulation, some IL-4-producing murine CD8+ T cell clones express CD40 ligand (CD40L), and they potentiate proliferation and immunoglobulin secretion by small resting B cells. Thus, the CD8+ T cell subsets T cytotoxic 1 (Tc1) and Tc2 are analogous to CD4+ T helper 1 (Th1) and Th2. IL-2 production by naive CD8+ cells requires co-stimulation. IL-4 production by CD8+ T cells requires the presence of IL-4 during initial stimulation. Some IL-4-producing CD8+ T cells express CD40L following TCR stimulation and provide help for B cells.

Animals↗
PubMed1994

Requirements for activation of CD8+ murine T cells. I. Development of cytolytic activity.

Cytolytic effector function fails to develop if proliferation of allospecific cytolytic T lymphocyte precursors is inhibited, but the requirements for generation of cytolytic activity have not been fully defined. In contrast, the cytolytic effector function of cytolytic T lymphocyte clones does not change during the cell cycle, and the level of cytolytic activity is independent of cellular proliferation. The requirement for proliferation by primary responding populations may reflect the need for clonal expansion of a few inherently cytolytic effector cells in order to reach a threshold number which can readily be detected in conventional cytolytic assays. Alternatively, proliferation may be required for cytolytic T lymphocyte precursors to differentiate into mature, functional cytolytic cells. Using CD8+ T cells which express an antigen-specific transgenic alpha/beta T cell receptor, we have studied the requirements for acquisition of cytolytic capacity. Stimulation of the T cell receptor alone appears to be sufficient to render naive, CD8+ transgenic T cells sensitive to the growth effects of interleukin-2 (IL-2), and in some circumstances to interleukin-4 (IL-4), but not to induce either lymphokine production or cytolytic activity. Costimulatory molecules expressed by allogenic stimulating cells appear to be required for lymphokine production, and CD8+ transgenic T cells initially appear to secrete only IL-2 and interferon-gamma. Stimulation of the T cell receptor of naive, CD8+ transgenic T cells appears to induce cytolytic activity only if cell proliferation occurs, either in response to IL-2 produced by the stimulated cells themselves when costimulatory molecules are present, or to IL-2 or IL-4 from exogenous sources if costimulatory molecules are absent.

Animals↗
PubMed1993

Cytolytic activity of murine IL-2-producing CD4+ and CD8+ T cell clones cycles in response to IL-2.

Alloreactive or OVA-reactive cloned murine CD4+ or CD8+ T cells that produce IL-2 exhibit greatly reduced cytolytic activity after being cultured with high concentrations of rIL-2. Furthermore, such cells fail to produce lymphokines or proliferate when stimulated with Ag. The duration of this unresponsiveness to Ag correlates with the concentration of rIL-2 to which the cells were exposed; higher concentrations of rIL-2 prolong the period of unresponsiveness. The presence of ionomycin during the cytolytic assay restores lytic activity to cells rendered unresponsive by exposure to rIL-2. These results suggest that rIL-2-induced unresponsiveness to Ag is a consequence of impairment of a calcium-dependent signal important for cytolysis, proliferation, and lymphokine production. Thus, IL-2 appears to be an important lymphokine that regulates T cell responses downward as well as upward.

Animals↗
PubMed1993

Identification and propagation of a putative immunosuppressive orphan parvovirus in cloned T cells.

A putative parvovirus related to minute virus of mice (MVM), but distinct from MVM-prototype and MVM-immunosuppressive, was identified, using serologic techniques and Southern blot analysis, in maintenance cultures of established T cell clones. This putative viral agent resulted in a lytic infection of cloned L3 cytotoxic T cells but was unable to produce a productive infection in BHK.21 or EL-4(G) cells. Moreover, maintenance cultures of several distinct subsets of cloned T cells apparently contaminated with this putative viral agent contained poorly growing cells and erythrocyte aggregates. The aggregation of mouse erythrocytes appeared to be a reliable indicator of infection with this putative virus and may be related to the ability of this agent to agglutinate mouse erythrocytes. This putative virus also was found to inhibit the proliferative response of certain cloned T cells to IL-2 and Ag. Viremic mice and secondary MLC supernatant were identified as two potential sources of contamination and represent ways of propagating this agent in vitro. The finding that this agent interferes with the ability of T cell clones to thrive and, therefore has the potential to alter immune responses, emphasizes the importance of identifying and excluding parvoviral infections in cultures of murine T lymphocytes.

Animals↗
PubMed1988

In vitro susceptibility of Cryptococcus neoformans isolates from patients with acquired immunodeficiency syndrome.

Cryptococcus neoformans strains from 26 individual patients with acquired immunodeficiency syndrome (AIDS) and three isolates from patients without AIDS were tested for their susceptibility to amphotericin B, flucytosine, ketoconazole, and miconazole nitrate. Ninety percent of the C neoformans isolates from patients with AIDS were inhibited by drug concentrations within achievable serum levels. The minimum fungicidal concentration of the four tested antifungal agents, however, exceeded obtainable cerebrospinal fluid levels.

Acquired Immunodeficiency Syndrome↗