Biomedical subjects

J I Greenfeld

Publications and source records attributed to J I Greenfeld.

5 recordsLinked to original sources

PubMed1997

Acute pancreatitis.

The etiology of acute pancreatitis in children is widely varied and includes idiopathic, drug-related, congenital, and posttraumatic causes. Most children have abdominal pain and tenderness without evidence of peritonitis, and most patients will have elevated serum amylase levels initially or after a delay of about 12 hours. If the diagnosis remains equivocal or in the setting of trauma, an abdominal CT scan should be obtained. Initial treatment for all forms of acute pancreatitis includes bowel rest and support with intravenous fluids. A nasogastric tube should only be placed for symptomatic relief and prophylactic broad-spectrum antibiotics should be given only in the setting of necrotizing pancreatitis, especially if patients are receiving pharmacologic immunosuppression. Fever or decline in clinical status should prompt CT scan with intravenous contrast and possible fine needle aspiration to detect the presence of sterile or infected necrotizing pancreatitis. Positive cultures or severely worsening clinical status are indications for necrosectomy and debridement with sequential packing and explorations. All patients who have had an episode of gallstone pancreatitis should have a cholecystectomy after resolution of pancreatic inflammation but before discharge from the hospital.

Abdominal Injuries↗

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↗

PubMed1995

Decreased bacterial adherence and biofilm formation on chlorhexidine and silver sulfadiazine-impregnated central venous catheters implanted in swine.

OBJECTIVE: To determine if antiseptic central venous catheters impregnated with silver sulfadiazine and chlorhexidine (antiseptic) reduce bacterial adherence and biofilm formation without producing local or systemic toxicity. DESIGN: Prospective, randomized, controlled trial. SETTING: Experimental laboratory in a university teaching hospital. SUBJECTS: Ten outbred New Hampshire pigs. INTERVENTIONS: Nonimpregnated (control) and antiseptic-impregnated catheters were inserted intravascularly into swine for 7 days. After explantation, the catheters were assessed for bacterial adherence and biofilm formation, and the surrounding tissue was assessed for signs of toxicity. Before retrieval, systemic concentrations of antimicrobials were determined. MEASUREMENTS AND MAIN RESULTS: Sequential roll plate and centrifuging were used to detect moderately and tightly adherent bacteria on the outer and luminal surfaces of the catheter. The presence of biofilm was detected by scanning electron microscopy. Tissues surrounding the catheters were examined histopathologically; systemic concentrations of chlorhexidine, sulfadiazine, and silver were determined by atomic absorption and high-performance liquid chromatography. As compared with the controls, antiseptic catheters had significantly (p < .01) fewer moderately and tightly adherent bacteria on outer and luminal surfaces, and fewer adherent bacteria when outer surfaces alone were examined (p < .01). Scanning electron microscopy showed bacterial biofilm and adherence on the control catheters but not on the antiseptic catheters. There were no abnormal histopathologic changes associated with the test catheter, and serum concentrations of the antibacterial agents were shown to be within nontoxic ranges. CONCLUSION: The antiseptic-impregnated catheters prevented bacterial adherence and biofilm formation and produced no local or systemic toxicity.

Animals↗

PubMed1994

The effect of UVB irradiation on proliferative activity and cell growth potential of cord blood.

To determine the degree of graft versus host disease (GVHD) prophylaxis that might be necessary if cord blood (CB) transplantation is more widely applied, we compared human cord blood mononuclear cell (CBMC) and adult peripheral blood mononuclear cell (PBMC) proliferative responses and stimulatory capabilities; to examine the utility of UVB irradiation for GVHD prophylaxis, we compared proliferative responses, antigen-presenting cell (APC) stimulatory functions, and cytokine production by untreated and UVB-irradiated CBMCs. The two cell types, CBMC and PBMC, proliferated equally both in response to phytohemagglutinin (PHA) and alloantigen in mixed lymphocyte culture (MLC). Cord blood stimulatory function in MLC was significantly (P < 0.05) reduced to 60% of PBMC stimulatory capability. Ultraviolet-B irradiation at a dose of 100 J/m2 of CBMCs significantly (P < 0.01) inhibited PHA stimulation by 79.4%, reduced responder activity in MLC by 75.8%, and inhibited stimulatory activity in MLC by 55.6% as compared with the activity shown by untreated CBMCs. The same dose of UVB preserved 59.9% of CFU-GM and 65.9% of BFU-E colony growth as compared with untreated CBMCs. Production of lymphokines (IL-2, GM-CSF, LIF, and gamma-IFN) by PHA-stimulated CBMCs was decreased, but monokine (IL-1 beta and IL-6) production was unchanged. We conclude that UVB irradiation at a dose of 100 J/m2 inhibits CB lymphocyte activation and preserves the cellular growth potential of CB hematopoietic progenitor cells.

Antigen-Presenting Cells↗