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Biomedical subjects

L John

Publications and source records attributed to L John.

At least 19 recordsLinked to original sources
PubMed1995

Transplantation of G-CSF mobilized allogeneic peripheral blood stem cells in rabbits.

Mobilized peripheral blood precursor cells (PBPC) are used with increasing frequency to restore autologous hematopoiesis following high-dose radio-chemotherapy. The success of this method has aroused interest in the use of mobilized PBPC for allogeneic transplants. This approach would eliminate the need for marrow aspiration and general anesthesia. In this project we tested the feasibility of allogeneic histoincompatible PBPC transplants in rabbits. Adult outbred Red Burgundy rabbits were used as donors, histoincompatible New Zealand White rabbits of the opposite sex as recipients. One individual donor was used for one individual recipient. Conditioning consisted of 10 Gy total body irradiation (TBI). Donor animals were pre-treated with recombinant human granulocyte colony-stimulating factor (rh G-CSF) given s.c. at 10 micrograms/kg daily. Three schedules of PBPC collection and reinfusion were tested in 3 groups of animals, each consisting of 5 donor recipient pairs: (A) PBPC were collected either on days -2, -1 and 0, and infused at once after TBI on day 0; (B) collected and infused on days 0, +2, +4, +7, +9, and +11; (C) collected on 3 consecutive days, cryopreserved for 1 month and infused on day 0 followed by 3 fresh donations on days +4, +8 and +11. The median amount of blood processed from donor animals was 470 ml (312-602) containing about 10 x 10(8) (5-71 x 10(8)) nucleated cells. Recipient animals received a median of 2.7 x 10(8) cells/kg equivalent to 9.6 x 10(4) colony-forming units granulocyte-macrophages (CFU-GM)/kg (data derived from Group C of the animals).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Rate of progression of albuminuria in type II diabetes. Five-year prospective study from south India.

OBJECTIVE: To evaluate the potential risk factors for the progression of albuminuria in type II diabetes. RESEARCH DESIGN AND METHODS: A cohort of 481 type II diabetic patients were followed prospectively for 5 years. Blood glucose (BG) and blood pressure (BP) were checked at 2 monthly intervals, and urinary albumin excretion (UAE) was checked at yearly intervals. Progression of albuminuria was recognized by the development of microalbuminuria and macroalbuminuria and a significant increase in albuminuria within the microalbuminuric range. RESULTS: UAE was normal in 349 patients, 93 patients were microalbuminuric, and the rest (39) were macroalbuminuric. Sixty-two patients with normal UAE developed microalbuminuria. Ten patients with normoalbuminuria and 23 with microalbuminuria developed macroalbuminuria during the 5-year observation period with overall incidence of 46.9/1,000 person-years for normoalbuminuria and 58.7/1,000 person-years for microalbuminuria. Baseline UAE was significantly higher in those patients who progressed compared with those patients who did not (normoalbuminuria: 8.5 +/- 6 vs. 5.3 +/- 4 micrograms/min, P < 0.001; microalbuminuria: 68.5 +/- 57 vs. 47.4 +/- 34 micrograms/min, P < 0.01). Multiple regression analysis revealed initial UAE and diabetes duration to be predictors of albuminuria progression. CONCLUSIONS: Initial UAE is a strong predictor of albuminuria progression in type II diabetic patients.

Albuminuria↗
PubMed1992

Induction of a cell-transferable suppression of alloreactivity by photodamaged lymphocytes.

We have reported previously that splenocytes from BALB/c mice acutely rejecting CBA/j skin allografts were exposed to 8-methoxypsoralen (8-MOP) and ultraviolet A light and infused several times intravenously into naive BALB/c recipients; the recipients were hyporesponsive to CBA/j alloantigens in skin graft and delayed-type hypersensitivity assays, as well as in mixed leukocyte culture and cytotoxicity assays. We currently expand on this work by showing that donor-specific tolerance can be transferred adoptively to naive syngeneic animals via unfractionated splenocytes from mice rendered tolerant by the previous protocol. This suppressed response to alloantigen was transferred optimally with splenocytes taken from mice on the sixth day after the final treatment with PET cells. We further demonstrate that the cells that are adoptively transferring suppression are radiosensitive, Thy-1+, Lyt-2+, L3T4- T lymphocytes.

Animals↗
PubMed1992

DNA associated with the cell membrane is involved in the inhibition of the skin rejection response induced by infusions of photodamaged alloreactive cells that mediate rejection of skin allograft.

Cell membrane DNA (cmDNA) is a form of DNA located on the surface of human and murine T-cells. It has recently been characterized as a target for photomodification by 8-methoxypsoralen (8-MOP) and long-wave ultraviolet light (UV-A). Whereas 8-MOP itself is biologically inert, photoactivated 8-MOP is covalently bound to pyrimidine bases in DNA. We have investigated the possible involvement of cmDNA photomodification in the induction of the suppression of skin allograft rejection in BALB/c mice preimmunized with 8-MOP/UV-A photodamaged alloreactive cells which mediates this allograft rejection. This suppression is demonstrated by inhibition of delayed-type hypersensitivity (DTH) and mixed leukocyte culture (MLC) responses. Splenocytes from BALB/c mice undergoing rejection of CBA/j skin graft which contained an expanded population of the effector T lymphocytes that mediate the rejection were treated with DNAse to remove cmDNA before or after treatment with 8-MOP and UV-A prior to infusion into naive BALB/c recipients. Mice that received pretreated effector cells were tested for MLC responses to CBA/j or B10 alloantigens before and after the DTH response. The DTH response of all groups of pretreated BALB/c mice to the relevant alloantigen was specifically suppressed as compared with the response of control mice. However, adoptive transfer of the suppression of the DTH response was optimally demonstrable only in syngeneic recipients of cells from donor mice treated with photodamaged alloreactive cells. Also, splenocytes from BALB/c mice immunized with photodamaged alloreactive cells demonstrated highly significant hyporesponsiveness and suppression of the MLC response of naive mice to the relevant alloantigen in the case of the primary MLC response, and to both alloantigens in the secondary MLC response which was totally eliminated by prior pretreatment of these effector cells with DNAse. Therefore, it appears that the suppression of the DTH response can be induced by pretreatment of the effector cells with DNAse and/or 8-MOP and UV-A but is adoptively transferable optimally only from mice which are recipients of photodamaged alloreactive cells. Moreover, the effectiveness of this treatment is decreased by prior removal of cmDNA from these cells. The presence of cmDNA is necessary for induction of suppression of the primary and secondary MLC responses in mice treated with photodamaged cells of allograft rejection.

Animals↗
PubMed1992

Betamethasone in tetanus patients: an evaluation of its effect on the mortality and morbidity.

The effect of betamethasone on the outcome in moderate to severe tetanus was studied in a randomised, double blind, placebo controlled study in 22 patients. The mortality rate was reduced by 36.1% with the addition of corticosteroids to the regime of treatment. Betamethasone did not alter the duration of intensive care in those requiring it, but reduced the need for tracheostomy and ventilation. The mean daily dose of diazepam required was not significantly different between the two groups and there was no increase in the incidence of infections in the betamethasone group.

Adult↗
PubMed1991

Inhibition of antiskin allograft immunity induced by infusions with photoinactivated effector T lymphocytes (PET cells). Is in vivo cell transferrable?

We previously reported producing donor-specific tolerance to alloantigens by intravenous exposure to pretreated antidonor T cells. The current study extends that work by adoptively transferring the donor-specific tolerance into naive syngeneic recipients. Eight days after BALB/c mice received histoincompatible CBA/j skin grafts, their splenocytes which included an expanded population of cells mediating rejection were treated with 100 ng/ml 8-methoxypsoralen (8-MOP) photoactivated by 1 Joule/cm2 of ultraviolet A (UVA) light prior to infusion into naive BALB/c recipients. Whereas 8-MOP itself is biologically inert, photoactivated 8-MOP crosslinks DNA by covalently binding to pyrimidine bases. Recipient BALB/c mice which had been previously demonstrated to be hyporesponsive to CBA/j alloantigens in mixed leukocyte culture (MLC), cytotoxicity (CTL) and in vivo delayed type hypersensitivity (DTH) assays were the donors of spleen cells for the adoptive transfer experiments. Fifty to one hundred million viable spleen cells from these pretreated BALB/c mice were transferred into naive syngeneic recipients which then were tested for DTH response and allograft survival to the relevant and irrelevant antigens. The radiosensitivity of this transferrable suppression was evaluated by exposing the adoptively transferred cell population to 3200 rads of C-irradiation prior to cell transfer. The phenotype of the cells transferring this suppressive response was performed by depleting specific populations of cells with monoclonal antibodies prior to cell transfer. In vivo the DTH response of the pretreated BALB/c mice was specifically suppressed to the relevant alloantigen, correlating with retention of CBA/j skin grafts for up to 42 days post engraftment without visual evidence of rejection, in comparison to control mice complete rejection of the skin graft in less than 8 days. In vitro, splenocytes from BALB/c recipients of pretreated syngeneic splenocytes containing large numbers of BALB/c anti-CBA/j T cells proliferated less in MLC and generated lower cytotoxic T cell responses to CBA/j alloantigens than did controls and suppressed the naive and sensitized BALB/c MLC and CTL responses to CBA/j alloantigen. This specific suppressive response to alloantigen was optimally transferred into syngeneic naive recipients when the adoptive transfer was performed on the sixth day after the last infusion received by the spleen cell donor mice. The adoptive transfer of this suppressive response was abrogated by the prior X-irradiation of the donor spleen cells and significantly abolished by the depletion of Thy-1+, Lyt-2+, L3T4- T lymphocytes.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Complement activation during bypass in acquired C1 esterase inhibitor deficiency.

Serial complement estimations during cardiopulmonary bypass are reported in a patient with acquired C1 esterase inhibitor deficiency. Although the extent of classic and alternative pathway activation appeared appropriate, exaggerated common pathway activation with massive increase in the C3d:C3 ratio occurred. A fatal hemostatic disorder, pulmonary edema, and circulatory collapse ensued despite prophylaxis and therapy.

Aged↗
PubMed1991

Inhibition of anti-skin allograft immunity induced by infusions with photoinactivated effector T lymphocytes--the congenic model.

We have previously reported the capacity to produce donor-specific tolerance to alloantigens by intravenous exposure to pretreated antidonor T cells. The current study has refined this system by using congenic mice differing only at the H-2 major histocompatibility complex genetic loci. Twelve days after B10 mice received MHC-incompatible B10.D2 skin grafts, their splenocytes that included an expanded population of cells mediating rejection were treated with 100 ng/ml 8-methoxypsoralen (8-MOP) photoactivated by 1 J/cm2 of ultraviolet A prior to infusion into naive B10 recipients. Whereas 8-MOP itself is biologically inert, photoactivated 8-MOP crosslinks DNA by covalently binding to pyrimidine bases. Recipient B10 mice were tested for tolerance to B10.D2 alloantigens in mixed leukocyte culture (MLC), cytotoxicity (CTL), and to in vivo delayed type hypersensitivity assays and challenged with a fresh B10.D2 graft. In vivo, the DTH response of the pretreated B10 mice was specifically suppressed to the relevant alloantigen, correlating with retention of B10.D2 skin grafts for up to 22 days postengraftment without visual evidence of rejection, in comparison to control complete rejection of the skin graft in less than 12 days. In vitro, splenocytes from B10 recipients of pretreated syngeneic splenocytes containing large numbers of B10 anti-B10.D2 T cells proliferated less in MLC and generated lower cytotoxic T cell responses to B10.D2 alloantigens than did controls and suppressed the B10 MLC and CTL responses to B10.D2 alloantigen. These results reveal that, in a highly defined congenic transplantation system, infusions of photoinactivated effector cells resulted in selective inhibition of the in vivo responses that correlated with allograft rejection and permitted prolonged retention of histoincompatible skin grafts. This approach may have significant practical applicability for treatment of human disorders caused by aberrant T cells.

Animals↗
PubMed1991

Hematologic values of New Zealand white rabbits determined by automated flow cytometry.

Hematologic values of peripheral blood from normal adult New Zealand White rabbits were determined by five different automated flow cytometers in use in a routine clinical hematology laboratory: Technicon H1, Coulter Counter CC540, Coulter Counter VCS, Sysmex NE8000 and Sysmex R1000. The software designed for human blood analysis was used in all instances without adaptation. The total numbers of white blood cells, red blood cells, reticulocytes and platelets were measured with high precision and accuracy. Except for hemoglobin content, concordance was excellent for all measured and calculated values among the different automated flow cytometers. Determining the white blood cell differential count was more complex. Eosinophils and lymphocytes were quantified reliably by all the automated flow cytometers used. However, the results were rejected by Technicon H1 and Sysmex NE8000 in 50% of the cases. Rabbit basophils were recognized with accuracy by Technicon H1 only. The proportion of polymorphonuclear versus mononuclear white cells was identical when measured with Technicon H1 and Coulter Counter VCS. These results show that the new generation of automated flow cytometers designed for human blood can be used with some limitations for animal studies. They allow the standardization of normal values and comparison of results among or between laboratories. They also introduce new parameters, the value of which is as yet undefined.

Animals↗
PubMed1991

Prevalence of diabetic nephropathy in non-insulin dependent diabetics.

Renal involvement was studied in 538 consecutive NIDDM subjects (271 males and 267 females). The mean (SD) age of males was 55.4 (11.0) and of females 51.0 (10.5). Diabetic nephropathy was present in 8.9 per cent of the patients (urinary albumin excretion greater than 200 micrograms/min) and another 19.7 per cent had microalbuminuria (20-200 micrograms/min). Male predominance was striking in the macroalbuminuric group (P less than 0.001). The age of the patients and duration of diabetes in patients with micro and macroalbuminuria were significantly higher as compared to those in normoalbuminuric group (P less than 0.001). Patients with micro and macroalbuminuria had significantly elevated blood sugars and blood pressures (P less than 0.01). The prevalence of vascular complications were found to be higher in the macroalbuminuric group (P less than 0.01). Male sex, older age, longer duration of diabetes, poor glycaemic control and raised blood pressure were significant risk factors in the development of diabetic nephropathy.

Adult↗
PubMed1990

Reduction of complement activation during bypass by prime manipulation.

Complement activation is believed to be of importance in the development of complications arising after cardiopulmonary bypass. The effect on complement activation of priming the extracorporeal circuit with crystalloid alone, crystalloid plus albumin, or crystalloid plus the plasma expander polygeline was assessed in 36 patients undergoing coronary artery operations with cardiopulmonary bypass using a bubble oxygenator. Activation of the alternative and common complement pathways was monitored before, during, and after the bypass period by measuring concentrations of factor B and its fragment Ba and C3 and its fragment C3d. Complement activation occurred in all three groups of patients, with no difference between the crystalloid and crystalloid-albumin groups. In contrast, Ba fragment concentrations were persistently and significantly lower during and after bypass in the polygeline group, denoting reduced complement activation. C3d levels also showed a tendency to be lower in this group. Our results indicate that addition of polygeline to the priming solution reduces complement activation. Because complement activation is associated with morbidity after cardiopulmonary bypass, addition of polygeline to the priming solution may offer an inexpensive method of reducing morbidity after cardiopulmonary bypass.

Albumins↗
PubMed1990

Complement activation before, during and after cardiopulmonary bypass.

Plasma levels of the complement parent molecules C3, C4, and factor B and their split products, C3d, C4d, and Ba were measured in 12 patients undergoing cardiopulmonary bypass for coronary artery surgery. Alternative and common complement pathway activation, demonstrated by statistically significant rising levels of Ba (P less than 0.05), and C3d (P less than 0.05) and by elevated Ba:B (P less than 0.05) and C3d:C3 (P less than 0.05) ratios were found before the institution of cardiopulmonary bypass but following heparin administration suggesting that heparin may itself initiate alternative pathway activation. In addition, significant depletion of parent complement components and elevation of split product concentrations was seen during bypass suggesting classical and alternate pathway activation (P less than 0.01). This study clarifies the pathways of complement activation during bypass and presents evidence that heparin administration may initially activate the complement cascade.

Cardiopulmonary Bypass↗
PubMed1990

Infective endocarditis due to Streptococcus sanguis I occurring on a normal mitral valve.

We report a 64 year old lady in whom infective endocarditis of the mitral valve occurred with no previous underlying heart disease. Streptococcus sanguis I was isolated on blood culture and 2-D echo cardiography showed a vegetation on the anterior mitral leaflet. The viridans group of streptococci are classically associated with subacute endocarditis occurring on structurally abnormal valves, but involvement of a normal valve by these organisms is rare.

Echocardiography↗
PubMed1989

Clinical profile of Indian non-insulin-dependent diabetics with nephropathy and renal failure.

We studied the clinical profile of 296 non-insulin-dependent diabetic (NIDDM) patients with nephropathy and renal failure. Male preponderance was striking in this group and the age of onset of diabetes was between 30 and 50 years in 75%. Retinopathy was present in 86% with proliferative changes in 20% and coronary artery disease was evident in 40% of the patients. The incidence of retinopathy and coronary artery disease was significantly higher in this group than in a group of non-insulin-dependent diabetics without nephropathy (86% vs. 18.5%; 40% vs. 30% respectively, P less than 0.01). It is our observation that patients with NIDDM developing nephropathy and renal failure have had an early onset of disease and are significantly more often male. There is also a greater incidence of elevated blood pressure, coronary artery disease and retinopathy in this group.

Adult↗