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T Graham

Publications and source records attributed to T Graham.

At least 55 records · Page 3Linked to original sources
PubMed1994

Trypanosoma brucei: characterization of protein kinases that are capable of autophosphorylation in vitro.

Autophosphorylation by protein kinases has been implicated as an important control mechanism in signal transduction and growth regulatory pathways in mammalian cells. We have set out to investigate whether any such autophosphorylating protein kinase activities can be found in Trypanosoma brucei. In order to do this, we have developed a system for characterizing such protein kinase activities using an in vitro assay. This assay was carried out by fractionation of trypanosome lysates using isoelectric focusing gel electrophoresis followed by incubation of the gel in gamma 32P-labelled nucleotide triphosphate and subsequent autoradiography. We have identified two classes of autophosphorylating protein kinase activities. In the first class all were dependent on ATP as the phosphate donor substrate and were all found to have a molecular size of 60 kDa. Differences in the activity of these protein kinases were observed between the bloodstream and procyclic life-cycle stages. Furthermore, the addition of mammalian epidermal growth factor to bloodstream stage lysates stimulated an additional activity. The second class of autophosphorylating protein kinases utilized GTP as the phosphate donor and were all found to be 90 kDa in size. Stage-specific differences were also observed in the activity of these protein kinases.

Adenosine Triphosphate↗
PubMed1994

Gamma-irradiation of pretransplant blood transfusions from unrelated donors prevents sensitization to minor histocompatibility antigens on dog leukocyte antigen-identical canine marrow grafts.

Pretransplant blood transfusions from a dog leukocyte antigen (DLA)-identical canine littermate marrow donor will sensitize the recipient to non-DLA-linked polymorphic minor histocompatibility antigens, which uniformly results in graft rejection. We observed previously that 2000 cGy gamma-irradiation of marrow donor blood transfusions prevented this sensitization and subsequent marrow graft rejection. The purpose of the present study was to determine whether treatment of unrelated blood transfusions with gamma-irradiation would also prevent sensitization. Conceivably, sensitization to minor histocompatibility antigens might be more efficient or potent and thus more difficult to prevent when those antigens are seen in the context of disparity for DLA antigens. Furthermore, this model, in which sensitization to DLA-identical littermate marrow is caused by unrelated blood transfusions, is directly relevant to the clinical circumstances of human marrow transplantation. We assessed sensitization caused by unrelated blood transfusions by monitoring graft outcome in recipients transplanted with DLA-identical littermate marrow after conditioning with 920 cGy total body irradiation. Two thousand cGy gamma-irradiation of unrelated blood transfusions significantly reduced the incidence of transfusion-induced sensitization of recipients. There was successful marrow engraftment in 15 of 16 (94%, P < 0.003) of these animals in contrast to the previous study in which only 7 of 16 (44%) animals engrafted after they were transfused with unmodified blood on the same schedule. These results suggest that blood transfusions for use in humans, especially for patients with aplastic anemia, should be gamma-irradiated in order to reduce the incidence of marrow graft rejection caused by sensitization to minor histocompatibility antigens.

Animals↗
PubMed1994

Muscle lactate metabolism in recovery from intense exhaustive exercise: impact of light exercise.

This study examined the effect of low-intensity exercise on lactate metabolism during the first 10 min of recovery from high-intensity exercise. Subjects exercised (61.0 +/- 5.4 W) one leg to exhaustion (approximately 3.5 min), and after 1 h of rest they performed the same exhaustive exercise with the other leg. For one leg the intense exercise was followed by rest [passive (P) leg], and for the other leg the exercise was followed by a 10-min period with low-intensity exercise at a work rate of 10 W [active (A) leg]. The muscle lactate concentration after the intense exercise was the same in the P and A legs, but after 10 min of recovery, the lactate concentration and the arterial blood lactate level were higher for the P leg than for the A leg (both P < 0.05). During the recovery, the mean blood flow was lower for the P leg than for the A leg (P < 0.05), whereas the mean lactate efflux was not significantly different. During the 10 min of recovery, lactate release accounted for approximately 60% of the change in muscle lactate for either leg. The leg excess postexercise O2 consumption during 10 min of recovery was 440 and 750 ml for the P and A legs, respectively. The present data suggest that a lowered blood lactate level during active recovery is due to an elevated muscle lactate metabolism and is not caused by a transient higher release of lactate from the exercising muscles coupled with greater uptake in other tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1994

Students' learning of volleyball skills.

An examination of 222 students' learning of skill in volleyball was conducted in classes. Analysis indicated that over an eight-lesson unit performance for both serve and forearm pass improved. When classes were the unit of analysis five classes showed significant improvement on the serve and four on the pass. Present data provide a base for study of instructional effectiveness in physical education.

Humans↗
PubMed1994

'Resistance' to unrelated, DLA-nonidentical canine marrow grafts is unrestricted by the major histocompatibility complex.

Dogs undergoing rejection of unrelated, dog leukocyte antigen (DLA)-nonidentical marrow grafts show an increase in mononuclear cell counts in the peripheral blood at 1 week after transplant. Cells are of host origin and express phenotypic and morphologic characteristics of large granular lymphocytes (LGLs). LGLs from rejecting dogs suppress in vitro growth of donor marrow colony-forming units-granulocyte/macrophage (CFU-GM) and have natural killer (NK) cell activity. The current study tested whether the marrow-suppressive activity of LGLs obtained at the time of marrow graft rejection was major histocompatibility complex (MHC)-restricted. Five dogs were in the process of rejecting their DLA-nonidentical unrelated marrow grafts after conditioning with 9.2 Gy total-body irradiation (TBI). At the time of rejection, peripheral blood mononuclear cells (PBMC) were harvested. PBMC were co-cultured with marrow obtained from the original marrow transplant donor and from other unrelated dogs that were either DLA-identical or -nonidentical with the marrow donor. A statistically significant reduction of marrow donor CFU-GM was seen when compared to results with autologous effector PBMC from the marrow donor. The number of colonies with recipient effector PBMC ranged from 8 to 75% (median 29%). No suppression was seen with PBMC effectors from unrelated DLA-identical or DLA-nonidentical dogs. Similarly, significant reductions in the number of CFU-GM compared to autologous controls were seen with effector PBMC from marrow recipients and marrow target cells, both from unrelated dogs that were phenotypically DLA-identical or -nonidentical with the marrow donor. The number of colonies ranged from 6 to 68% (median 29%) and 1 to 102% (median 20%), respectively. NK activity was present at low levels in all recipients, while specific alloantigen-primed cytotoxic T cell killing by cells obtained from the five recipients yielded cytolysis of donor PBMC in only one case, suggesting that the marrow-suppressive activity was NK cell-mediated. In conclusion, PBMC from canine marrow transplant recipients undergoing rejection of DLA-nonidentical marrow grafts suppress in vitro CFU-GM growth of marrow donor cells, and this suppression is not MHC-restricted.

Animals↗
PubMed1994

Recipient-specific donor cytotoxic T lymphocytes enhance engraftment of unrelated, DLA non-identical canine marrow.

Resistance to canine marrow grafts from unrelated DLA non-identical donors can be overcome by infusion of viable donor peripheral blood leukocytes or thoracic duct cells in addition to the marrow. The mechanisms by which these cells enhance engraftment are unknown but are likely to include a graft-versus-host reaction. The current study investigated whether recipient-specific, donor alloreactive cytotoxic lymphocytes mediating a graft-versus-host reaction could abrogate resistance to canine marrow grafts. To this purpose, cytotoxic donor lymphocytes (CTL) specific for recipient DLA antigens were generated in vitro and expanded in culture by exogenous interleukin-2 (IL-2). Two groups of dogs were studied. All were given 9.2 Gy total body irradiation followed by 3.7 x 10(8) marrow cells/kg from an unrelated DLA non-identical donor on day 0 and 1.2 x 10(8) host-specific CTL/kg on days 1 and 2. Dogs in group 2 were given, in addition, subcutaneous injections of recombinant human IL-2, 10,000 U/kg twice daily on days 1 through 10 post-grafting. Ten of 16 dogs in the two groups showed hematopoietic engraftment regardless of whether they received in vivo IL-2. Engraftment in current dogs was significantly better than that in 47 controls given marrow alone (p = 0.001), although it was worse than that in 64 dogs given marrow and an order of magnitude higher number of viable mononuclear cells obtained from the peripheral blood (p = 0.007).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Marrow toxicity of fractionated vs. single dose total body irradiation is identical in a canine model.

PURPOSE: We explored in dogs the marrow toxicity of single dose total body irradiation delivered from two opposing 60Co sources at a rate of 10 cGy/min and compared results to those seen with total body irradiation administered in 100 cGy fractions with minimum interfraction intervals of 6 hr. Dogs were not given marrow transplants. RESULTS: We found that 200 cGy single dose total body irradiation was sublethal, with 12 of 13 dogs showing hematopoietic recovery and survival. Seven of 21 dogs given 300 cGy single dose total body irradiation survived compared to 6 of 10 dogs given 300 cGy fractionated total body irradiation (p = .18). One of 28 dogs given 400 cGy single dose total body irradiation survived compared to none of six given fractionated radiation (p > .20). With granulocyte colony stimulating factor administered from day 0-21 after 400 cGy total body irradiation, most dogs survived with hematological recovery. Because of the almost uniform success with granulocyte colony stimulating factor after 400 cGy single dose total body irradiation, a study of granulocyte colony stimulating factor after 400 cGy fractionated total body irradiation was deemed not to be informative and, thus, not carried out. Additional comparisons between single dose and fractionated total body irradiation were carried out with granulocyte colony stimulating factor administered after 500 and 600 cGy of total body irradiation. As with lower doses of total body irradiation, no significant survival differences were seen between the two modes of total body irradiation, and only 3 of 26 dogs studied survived with complete hematological recovery. Overall, therefore, survival among dogs given single dose total body irradiation was not different from that of dogs given fractionated total body irradiation (p = .67). Similarly, the slopes of the postirradiation declines of granulocyte and platelet counts and the rates of their recovery in surviving dogs given equal total doses of single versus fractionated total body irradiation were indistinguishable. CONCLUSION: Within the limitations of the experimental design, we conclude that single-dose and fractionated total body irradiation have comparable marrow toxicity in dogs.

Animals↗
PubMed1993

Return to work following coronary artery bypass surgery or percutaneous transluminal coronary angioplasty.

Return to work (RTW) and other treatment outcomes of coronary artery bypass graft (CABG) and percutaneous transluminal coronary angioplasty (PTCA) patients were compared. Consecutive patients at one centre (n = 112 CABG and 119 PTCA patients) were interviewed 6-18 months following treatment (groups were similar in sex and social class). Pre-treatment employment levels were similar (41 and 38% for CABG and PTCA groups, respectively). PTCA patients were more likely to smoke, have angina, have less advanced cardiovascular disease and have been advised to stop working for medical reasons pre-treatment. Post-treatment levels of employment increased significantly. RTW rates were similar for CABG and PTCA groups (59 and 68% respectively). Both groups had reduced smoking to similar levels. The PTCA group continued to have higher levels of angina. For those without angina, PTCA patients were significantly more likely to return to work (73 vs 55%, P < 0.01). Both CABG and PTCA resulted in increased employment post-treatment.

Angina Pectoris↗
PubMed1993

Lactate and H+ effluxes from human skeletal muscles during intense, dynamic exercise.

1. Lactate and H+ efflux from skeletal muscles were studied with the one-legged knee extension model under conditions in which blood flow, arterial lactate and the muscle-blood lactate concentration gradient were altered. Subjects exercised one leg twice to exhaustion (EX1, EX2), separated by a 10 min recovery and a period of intense intermittent exercise. After 1 h of recovery the exercise protocol was repeated with the other leg. Low-intensity exercise was performed with one leg during the recovery periods, while the other leg was passive during its recovery periods. 2. Prior to, and immediately after, EX1 and EX2 and then 3 and 10 min after EX1, a biopsy was taken from the vastus lateralis of the exercised leg for lactate, pH, muscle water and fibre-type determinations. Measurements of leg blood flow and venous-arterial differences for lactate (whole blood and plasma), pH, partial pressure of CO2 (PCO2), haemoglobin, saturation and base excess (BE) were performed at the end of exercise and regularly during the recovery period after EX1. 3. The lactate release was linearly related (r = 0.96; P < 0.05) to the muscle lactate gradient over a range of muscle lactate from 0 to 45 mmol (kg wet wt)-1. The muscle lactate transport was evaluated from the net femoral venous-arterial differences (V-Adiff) for lactate. This rose with increases in the muscle lactate gradients, but as the gradient reached higher levels the V-Adiff lactate responded less than at smaller gradients. Thus, the lactate transport over the muscle membrane appears to be partly saturated at high muscle lactate concentrations. 4. The percentage of slow twitch (%ST) fibres was inversely related to the muscle lactate gradient, but it was not correlated to the lactate release at the end of the exercises. In spite of a significantly higher blood flow during active recovery, the lactate release was the same whether the leg was resting or performed low-intensity exercise in the recovery periods. In several other conditions the muscle lactate and H+ gradients would have predicted that the V-Adiff lactate would have been greater than it actually was. Thus, a variety of factors affect muscle lactate transport, including arterial lactate concentration, muscle perfusion, muscle contraction pattern and muscle morphology. 5. The muscle and femoral venous pH declined during EX1 to 6.73 and 7.14-7.15, respectively, and they increased to resting levels during 10 min of either passive or active recovery.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

Skeletal muscle ammonia production and repeated, intense exercise in humans.

We investigated the impact of repeated, high-intensity exercise on NH3 metabolism using the single-leg knee extensor model. The muscle glycogen level would be lowered by the initial exercise and low glycogen may stimulate NH3 production independent of any other effects of previous exercise. Therefore a high muscle glycogen condition was included in the protocol so that the pre-exercise glycogen concentration would be at least at a normal resting level for the second exercise. The subjects (n = 6) used previous exercise and (or) diet to begin the exercise with either normal (87.0 +/- 14.4 mmol/kg wet weight) or high (176.8 +/- 22.9 mmol/kg wet weight) glycogen (C and HG, respectively) in the quadriceps. They exercised (Ex1) one leg to exhaustion (140% leg VO2 max), rested 1 h, repeated the exercise (Ex2), and then repeated the protocol with the opposite leg. The exercise durations of Ex1 and Ex2, respectively, for C were 2.82 +/- 0.51 and 2.47 +/- 0.47 min (p < 0.05) and for HG were 2.92 +/- 0.57 and 2.77 +/- 0.50 min. The NH3 efflux was reduced (p < 0.05) from Ex1 to Ex2 in both C (516 +/- 159 and 250 +/- 69 mumol, respectively) and HG (618 +/- 233 and 275 +/- 124 mumol, respectively). While NH3 efflux was virtually identical between C and HG in both Ex1 and Ex2, HG consistently had a greater arterial NH3 concentration (p < 0.05). The decreased efflux in Ex2 compared with Ex1 was not due to greater accumulation of muscle NH3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

A labor perspective on workplace reproductive hazards: past history, current concerns, and positive directions.

The Supreme Court's March 1991 ruling in United Automobile Workers (UAW) versus Johnson Controls barring corporate "fetal protection policies" was a major victory for women's employment rights and has health and safety implications for both sexes. However, 2 years after the Court's decision, the union's work is far from over. The UAW has yet to see what policy Johnson Controls will implement in place of the old one. Formulating solutions to the concerns of workers who are exposed daily to reproductive health hazards on the job will continue to be on labor's agenda. Preventing hazardous exposures is the first priority. This goal would be furthered by setting occupational health and safety standards designed to protect workers' general and reproductive health. Support for the Comprehensive Occupational Safety and Health Reform Act (COSHRA) would also positively affect health and safety in the workplace. Where hazards have not yet been abated, the framework of transfers and income protections for all workers with temporary job restrictions should be examined. The Legal/Labor Working Group convened at the Occupational and Environmental Reproductive Hazards Working Conference authored guidelines for developing a model reproductive hazards policy. These recommendations can serve as a guide for implementation of nondiscriminatory and health-protective policies by employers.

Female↗
PubMed1993

Early results of combined carotid endarterectomy and coronary artery bypass grafting in patients with severe coronary and carotid artery disease.

The management of patients with carotid artery disease who require coronary artery bypass grafting (CABG) remains controversial. Several published series from the USA (including one with prospective randomization) advocate a combined approach of carotid endarterectomy (CEA) followed immediately by coronary artery bypass surgery. However, experience of combined carotid endarterectomy and coronary bypass grafting has not been previously reported by a centre from the United Kingdom. Between 1986 and 1991 we performed this combined procedure on 18 patients who required myocardial revascularization and had co-existing severe (> 70%) carotid stenosis. Sixteen patients (89%) had angina and 11 patients (61%) had symptomatic carotid artery disease. The perioperative mortality was 5.5% and the ipsilateral perioperative stroke rate was 5.5%. These early results are encouraging and suggest that further evaluation of combined carotid endarterectomy and coronary artery bypass surgery is warranted.

Adult↗
PubMed1993

Splenectomy does not enhance engraftment of DLA-nonidentical marrow transplants.

Previous studies in mice and monkeys suggested that either splenic irradiation of splenectomy led to enhanced allogeneic marrow engraftment. These findings suggested that a population of radiation-resistant host cells involved in mediating marrow graft rejection are sequestered in the spleen. In this current study, the effect of splenectomy in dogs receiving 9.2 Gy total body irradiation (TBI) and unrelated dog leukocyte antigen (DLA)-nonidentical donor marrow grafts was studied. We found that splenectomy did not significantly change the incidence of graft failure as compared to that observed in previously and concurrently transplanted nonsplenectomized recipients.

Animals↗
PubMed1992

A sequence in beta-hexosaminidase from Dictyostelium discoideum required for sorting of proteins to a compartment involved in developmentally induced secretion.

To study the sorting of proteins in Dictyostelium discoideum, we used vector constructs that contain cDNA coding for the entire beta-hexosaminidase protein to prepare transformants of a mutant that lacks this enzyme activity. These transformants overexpressed active, normally processed beta-hexosaminidase. The overexpressed enzyme colocalized with other acid hydrolases in the soluble fraction of vesicles in the lysosomal region of Percoll gradients. The sorting of other hydrolases was unaltered. We also prepared transformants with constructs that contain 22 (Hex 22-Inv), 70 (Hex 70-Inv), and 532 (Hex 532-Inv) amino-terminal amino acids from beta-hexosaminidase fused in frame with the coding sequence for the yeast SUC2 gene product, invertase. Fusion molecular masses were those expected for fully N-glycosylated proteins. Hex 22-Inv was rapidly (t1/2 less than 30 min) and quantitatively secreted. The others were slowly (t1/2 greater than 5 h) and partially secreted. Each expressed invertase activity. During growth, the invertase activity of Hex 70-Inv and Hex 532-Inv was retained to the same extent as that of endogenous lysosomal enzymes. Most of the Hex 70-Inv migrated in Percoll gradients with vesicles of intermediate density (d = 1.055), but a portion co-migrated with lysosomal enzymes at d = 1.08. Hex 70-Inv was sulfated, and its N-glycosides were resistant to endoglycosidase H, indicating Golgi processing. Hex 70-Inv and Hex 532-Inv, like endogenous lysosomal enzymes, were subject to developmentally induced secretion.

Animals↗
PubMed1992

Pharmacologic, toxicologic, and marrow transplantation studies in dogs given succinyl acetone.

A novel immunosuppressant, succinyl acetone (4,6-dioxoheptanoic acid), was studied in dogs. Results with bolus intravenous injections at doses ranging from 50 to 1600 mg/kg showed dose-dependent alpha and beta half-lives, ranging from 30 to 80 min and 7 to 27 hr, respectively. Results suggested that continuous i.v. infusion was necessary to maintain constant plasma levels. Four dogs were given 9.2 Gy total-body irradiation and autologous marrow transplants along with continuous i.v. infusion of succinyl acetone at 50, 100, 200, or 400 mg/kg/day for 21 days, and all four had rapid, sustained hematopoietic engraftment. However, two of the four dogs receiving 200 and 400 mg succinyl acetone/kg/day, respectively, developed bilateral hind-limb ataxia, with histologically confirmed cerebellar lesions in the dog given the higher dose, thus establishing a potential dose-limiting neurotoxicity. Prevention of graft-versus-host disease was studied in recipients of allogeneic marrow. Dogs were given 9.2 Gy TBI, followed by hematopoietic grafts from unrelated DLA-nonidentical or DLA-haploidentical littermate dogs. Succinyl acetone was given as continuous infusion for 21 days after transplant at doses of 100-300 mg/kg/day. Starting succinyl acetone on the day of marrow infusion in four dogs failed to prevent rapid onset of acute GVHD, and dogs survived no longer than controls. Starting succinyl acetone 3 days before transplant delayed the onset of acute GVHD and prolonged survival significantly compared with that of dogs not given postgrafting immunosuppression (P = 0.008); survival was comparable to that in previously reported dogs given either methotrexate or cyclosporine as postgrafting immunosuppression (P = 0.88 and 0.99, respectively). Seven of the sixteen allogeneic recipients developed evidence of neurotoxicity during succinyl-acetone infusion. Neurological dysfunctions were manifested by hind-limb ataxia and posterior paresis. In conclusion, succinyl acetone significantly delayed the onset of GVHD and prolonged survival of DLA-nonidentical marrow graft recipients but did not induce graft-host tolerance and was associated with dose-limiting neurotoxicity.

Animals↗