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Biomedical subjects

M A Hardy

Publications and source records attributed to M A Hardy.

At least 55 records · Page 3Linked to original sources
PubMed1996

UVB irradiation of human-derived peripheral blood lymphocytes induces apoptosis but not T-cell anergy: additive effects with various immunosuppressive agents.

UVB irradiation of bone marrow or pancreatic islets has been shown to prevent GVHD and to induce transplant tolerance in experimental animal models. To clarify the underlying mechanism(s) responsible for these UVB effects we have examined in vitro cell function following UVB irradiation using LDA, FACS analysis, and DNA gel electrophoresis to assess the role of UVB-induced anergy and/or cell death. To extend our studies to the clinical setting and to promote chimerism and tolerance to organ allografts, we have further studied the effects of UVB irradiation combined with the commonly used immunosuppressive agents (cyclosporine, azathioprine, and methylprednisolone) on human T cells in proliferative in vitro assays. When cytotoxic and proliferative responses to allogeneic cells or to PHA stimulation were evaluated in LDA, the use of increasing doses of UVB irradiation resulted in a dose-dependent decrease in proliferative and cytotoxic responses of T-cells as seen by decreases in precursor frequencies. The results of proliferative T-cell assays suggest an additive immunosuppressive effect of various immunosuppressive drugs when combined with UVB irradiation. Gel electrophoresis of DNA derived from resting and activated, UVB-irradiated PBLs showed apoptosis at all UVB doses used. FACS analysis of UVB-treated CD2+ cells resulted in a UVB dose-related decrease in cell numbers that correlated with viability studies. It appears that UVB irradiation of both activated and resting PBLs induces programmed cell death but not anergy of T-cells.

Apoptosis↗
PubMed1996

UVB-irradiation of human bone marrow: potential for donor specific tolerance.

Bone marrow mononuclear cell (BMMC) transplant may serve to produce donor specific tolerance for a coincident solid organ graft, but with the risk of graft versus host disease (GVHD). We examined in vitro the immunomodulatory effect of UVB on human BMMCs as potential prophylaxis against GVHD for clinical transplantation. After 10-200 J/m2 UVB-irradiation, BMMCs were examined by proliferative response (in mixed lymphocyte reaction and following phytohemagglutinin stimulation) and by cytokine profile. We also evaluated CFU-GM, CFU-GEMM, and BFU-E progenitor viability by 2-week methyl cellulose cultures following UVB-irradiation. Parallel studies were applied to marrow that was T-cell depleted by soybean agglutination (SBA) or by SBA and sheep erythrocyte rosetting (SBA-E-). We found that (1) UVB produces a dose-dependent inhibition of the proliferative response to stimulators by human BMMCs; (2) increasing doses of UVB-irradiation and increasing levels of T-cell depletion (TCD) are both inversely related to production of lymphokines (IL2, IL3, LIF, IFN-gamma, and GMCSF) and (3) T-cell depletion, but not UVB-irradiation, decreases the production of monokines (IL1, TNF, IL6). Progenitor cell viability was decreased but preserved at 100 J/m2 of UVB. Our findings suggest that UVB compares favorably with TCD as a technique for inhibition of GVHD and therefore that UVB-modulation of bone marrow (BM) inoculum may be useful in the prevention of GVHD in clinical bone marrow transplantation accompanying a solid organ graft.

Bone Marrow↗
PubMed1996

The mechanism of UVB prevention of graft versus host disease.

We have previously demonstrated that Ultraviolet B (UVB) irradiation of Lewis donor bone marrow (BM) allografts prevents graft versus host disease (GVHD) in ACI recipients while allowing full engraftment. In a one-way GVHD model of parent to Lewis X BN (F1) rats, the site and mechanism of the action of UVB irradiation was assessed by adding nonirradiated isolated cell subsets, isolated by monoclonal antibodies (Mab) to cell surface markers, to the reconstituting UVB-irradiated bone marrow inoculum. GVHD was assessed primarily on clinical grounds by observation of posture, alopecia, skin erythema, and weight loss. The addition of nonirradiated spleen cells or non-UVB-irradiated T-cell subsets (both CD4 and CD8 positive) to the otherwise UVB-irradiated donor inoculum consistently resulted in acute GVHD. In contrast, UVB irradiation of these cells resulted in full engraftment without acute GVHD. Mixed lymphocyte culture (MLC) assays confirmed responsiveness by BM transplanted hosts to third party stimulators while coculture assays failed to show any in vitro suppressor activity in the host. We conclude that UVB acts on both the T-lymphocyte and antigen presenting cell (APC) subsets to prevent acute GVHD. We also propose a model to explain tolerance based on clonal anergy produced by modified antigen presentation by UVB-irradiated APC's or by a modified response to processed antigen.

Animals↗
PubMed1996

Localization of endocrine pancreatic islets.

Transplantation of whole pancreas or pancreatic islets remains a promising approach to treatment of diabetes mellitus. Because at present there is no efficient method for in vivo early diagnosis of pancreatic islet rejection or for disorders of pancreatic endocrine function, we examined if dithizone (DTZ) and a synthetic iodo-derivative of DTZ (I-DTZ) can be used as a potential radioactive marker for monitoring viable transplanted pancreatic islets. Human pancreatic islets harvested from multiorgan donors were tested ex vivo after intraductal injection of DTZ solution for islet staining. Lewis rats were used in the in vivo experiments for localizing pancreatic islets in situ after intravenous injection of various concentrations of DTZ or I-DTZ. Fresh rat islets were transplanted into streptozotocin-induced diabetic recipients, either underneath the kidney capsule or intraperitoneally. Intravenous DTZ or I-DTZ was then used for macroscopic and microscopic identification of viable transplanted islets. These studies indicate that DTZ and I-DTZ solutions specifically stain pancreatic islets in vivo after intravenous injection without damage to their endocrine function as assessed by plasma insulin and glucose levels. Human islets stain red in in vitro studies similar to the DTZ (I-DTZ) effect in rats. We conclude that DTZ and I-DTZ are effective in the in vivo and in vitro identification of pancreatic islets and may have potential clinical application in the detection of pancreatic islet tumors (insulinomas) and in the diagnosis of rejection of pancreatic organ allografts or islets.

Animals↗
PubMed1996

What can you do about your patient's dry skin?

Water, absorbed through bathing, will hydrate skin but will rapidly be lost to evaporation unless a topical occlusive agent is applied to prevent moisture loss through the skin. The frequency of bathing (at least 5 times or more weekly) is more important than the mode of bathing (tub vs. shower) in effectively treating dry skin. In addition to the elements critical to prevention of dry skin through bathing practices, environmental humidity and fluid intake must be therapeutic.

Aged↗
PubMed1996

Fludarabine phosphate: A DNA synthesis inhibitor with potent immunosuppressive activity and minimal clinical toxicity.

Fludarabine phosphate selectively eliminates normal and malignant mononuclear cells in large animals and man through the inhibition of DNA synthesis. The drug depletes mononuclear cells from culture within 24 hours of initial exposure, CD4 and CD8 T cells being more sensitive than either CD20 B cells or CD34 bone marrow precursors. Mitogenic activation of lymphocytes enhances cellular elimination from culture. Fludarabine inhibits PHA-induced T-cell proliferation by >90 per cent and mixed lymphocyte reactions (allogeneic and xenogeneic) by >95 per cent. Fludarabine exerts its cytolytic effects through the induction of endonuclease-independent apoptosis. A 5-day course of fludarabine (50 mg/m2 intravenously once daily) induces both T- and B-cell lymphopenia in Cynomolgus monkeys and Papio baboons. Transient neutropenia was the only side-effect seen in experimental animals. Pretreatment of Cynomolgus monkeys with this regimen of fludarabine causes a prolongation of ABO-compatible skin allograft survival from 8 days (control) to 16 days (drug treated group). Secondary allotransplantation into presensitized recipients showed a similar prolongation of graft survival with fludarabine pretreatment (8 days vs 5 days control). Fludarabine promises to be a potent immunosuppressive agent with low clinical toxicity.

Animals↗
PubMed1996

Nurse-physician communication: perceptions of nurses at an Army medical center.

The purposes of this study were to describe nurses' perceptions of their communication with physicians, as related to the openness of the communication, the accuracy of the information communicated, and the timeliness of the interaction; and further, to determine if specific demographic characteristics of nurses are associated with perceptions of positive communication. The sample (N = 112) consisted of professional nurses working on one of nine inpatient units at a major military medical center. Shortell's ICU Nurse-Physician Communication subscale was used to measure the nurses' perceptions of the degree to which openness, accuracy, and timeliness described their communication with physicians. Overall findings were that the nurses perceived a poor quality of communication between themselves and the physicians with whom they interacted. Results from this study further indicated that the perceived quality of nurse-physician communication was not related to a nurse's educational level, length of nursing experience, or length of time assigned to a specific unit. Finally, findings provided no evidence that perceived levels of nurse-physician communication were greater among permanent staff than temporary nursing staff, or in intensive care units versus general ward areas.

Communication↗
PubMed1996

Evaluation and comparison of health care Work Environment Scale in military settings.

The purpose of this study was to describe health care providers' perceptions of their work environment at a large U.S. Army medical center, and to compare the findings to other military medical centers. The sample (N = 112) consisted of the professional nursing staff working on the nine inpatient units. The Work Environmental Scale (WES) was used to measure perceptions of the workplace relative to gender, position (head nurses, staff nurses, and agency nurses), specialty nursing (intensive care unit [ICU] versus non-ICU), education (MSN, BSN, and ADN), and patterns of differences between the WES subscales of four military medical centers. Results of the study indicate that there were no significant gender differences. Head nurses, non-ICU nurses, and MSN nurses perceived their environment more positively. There were significant differences in the WES subscales between the military hospitals. Implications for nursing using the WES were recommended.

Adult↗
PubMed1996

The effect of clinical and biochemical donor parameters on pancreatic islet isolation yield from cadaveric organ donors.

The recovery of pancreatic islet cells from cadaveric donors for allotransplantation may depend on the functional condition of the pancreas of the donor prior to organ harvesting. We examined donor hemodynamic and biochemical parameters and their effects on the subsequent yield of islet cells after harvesting. All pancreata were flushed and preserved in University of Wisconsin (UW) solution and digested using automated method within 8 hours. In the first analysis, digestions were divided into high-yield (> 2000 IEQ/g pancreas), and low-yield (< 2000 IEQ/g) groups and donor variables were averaged for each group. Donors whose pancreata yielded > 2000 IEQ/g received significantly greater amounts of Dopamine (14.43 micrograms/kg/min vs 9.35 mg/kg/min, p = 0.05). The daily urine output between groups was also significantly different. Maximum systolic blood pressure (SBP), minimum systolic blood pressure, use of vasopressin, length of hospitalization, and maximum base deficit were compared between the two groups. Less severe hypoglycemia (lowest blood glucose 143 mg/dL vs 107 mg/dL, p = 0.02) and lower amylase levels (36.2 U vs 80.7, p = 0.07 were noted in the high-yield group. A trend towards higher islet yields was associated with lowest hourly urine output > 60 (2040 IEQ/g vs 1649 IEQ/g p = 0.09), maximum SBP > 200 (2097 vs 1673, p = 0.07, and surprisingly, lowest SBP below 80 (2013 vs 1742, p < 0.1). Amount of fluids administered prior to procurement had no influence on islet yield. In conclusion, hemodynamic variables such as urine output, systolic blood pressure, and degree of pressor support were modestly associated with successful islet isolation. The preliminary data suggest that better multifactor donor analysis is imperative for standardization and monitoring of multiorgan donors. The association of higher blood glucose levels with successful isolation may also be related to resuscitation with dextrose-containing fluids.

Adenosine↗
PubMed1995

Prevention of graft-versus-host disease and the induction of transplant tolerance by low-dose UV-B irradiation of BM cells combined with cyclosporine immunosuppression.

GVHD is prevented and stable chimerism is induced in the rat BMT model by 700 J/m2 but not 100-500 J/m2 UV-B irradiation of allogeneic BM cells. Paradoxically, CsA which prevents GVHD in clinical BMT causes an aggressive autoimmune disease termed syngeneic GVHD in irradiated syngeneic BMT recipients after its withdrawal. Recently, we have shown that while 500-700 J/m2 UV-B irradiation of syngeneic BM cells combined with a 30-day course of CsA recipient immunosuppression impairs hemopoiesis due to lack of hemopoietic factors, a low dose of 100-300 J/m2 UV-B is effective in preventing CsA-induced autoimmune disease without endangering BM engraftment. This study extends these findings to the P-to-F1 hybrid and fully allogeneic rat BMT models and examines the effectiveness of low-dose UV-B irradiation of BM cells combined with a short course of CsA treatment in the prevention of GVHD and induction of transplant tolerance. Lethally gamma-irradiated (10.5 Gy) LBNF1 recipients of naive or UV-B irradiated (100-700 J/m2) BMT were treated with CsA (12.5 mg/kg/day) for 30 consecutive days after BMT. All lethally irradiated LBNF1 that did not receive BMT died in < 16 days, while animals transplanted with UV-B (700 J/m2) BMT survived > 1 year without GVHD. In contrast, all recipients of naive BMT died of lethal GVHD in < 50 days. Similarly, all recipients of naive BMT that received a 30-day course of CsA therapy developed severe GVHD with 60% mortality after cessation of CsA therapy. CsA-treated recipients of BMT irradiated with 700 J/m2 died between 12 and 25 days from failure of hemopoiesis. In contrast, CsA-treated recipients of 100-200 J/m2 UV-B irradiated BMT showed full BM engraftment without GVHD after cessation of CsA and survived > 1 year. These results were reproducible in the fully allogeneic UV-B BMT model. To test for donor-specific tolerance, the animals challenged 100 days after BMT with cardiac allografts accepted permanently (> 100 days) Lewis but not BN (non-BMT parental donor) cardiac allografts. Our results confirm that 700 J/m2 UV-B irradiation of BM cells combined with CsA recipient immunosuppression impairs the recovery capacity of stem cells while the use of lower UV-B (100-200 J/m2) is effective in preventing CsA-induced autoimmune disease without endangering BM engraftment and leads to induction of transplant tolerance.

Animals↗