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J R Pratt

Publications and source records attributed to J R Pratt.

35 records · Page 2Linked to original sources
PubMed1994

Evidence of alloreactive T suppressor cells in the maintenance phase of spontaneous tolerance after orthotopic liver transplantation in the rat.

In the DA-->PVG rat strain combination liver allografts are spontaneously tolerated and induce a state of systemic tolerance towards donor antigens. Thirty long-term (> 100 days)-surviving liver recipients in this strain combination were used to study humoral and cellular mechanisms of tolerance in the maintenance phase after liver transplantation. In the popliteal lymph node assay splenocytes of liver grafted or native PVG rats displayed a similar proliferative response in (DAxPVG)F1 hybrid rats, indicating an unaffected capacity of these cells to mount graft-versus-host reactions. Using adoptive transfer assays T-splenocytes (1x10(7) cells, MRC Ox 19+, MRC Ox12-, CD 5) of long-term-surviving liver recipients were able to suppress the rejection of DA hearts (donor-specific), of DA and AO kidney grafts in irradiated (300 cGy) PVG recipients. Serum of long-term-surviving liver recipients was able to suppress the rejection of semiallogeneic (DAxPVG)F1 heart grafts after double injection of 1 ml serum, while fully allogeneic DA heart as well as skin and pancreaticoduodenal grafts were resistant to passive enhancement. The results confirm the development of spontaneous tolerance after liver grafting in the DA-->PVG strain combination, and the demonstration of T cells with suppressive capacity in adoptive transfer experiments indicates a role for T suppressor cells in the maintenance phase of spontaneous tolerance after liver grafting.

Animals↗
PubMed1994

Use of fluorochromes for direct enumeration of total bacteria in environmental samples: past and present.

Understanding the role of bacteria in microbial food webs is intimately connected to the methods applied in the direct enumeration of bacteria. We have examined over 220 papers describing studies in which fluorochrome staining followed by epifluorescent microscopic direct counts was used to estimate total bacterial abundances. In this review, we summarize patterns in the use of 3,6-bis[dimethylamino]acridinium chloride (acridine orange) and 4',6-diamidino-2-phenylindole (DAPI), the two stains most frequently used in bacterial enumeration. The staining of samples with these fluorochromes, followed by filtration and direct counting of bacterial cells on filter surfaces, has become routine over the past 10 years. We examine trends in features of the standard direct count methods, such as sample preservation and preparation techniques, membrane filter types used, applied stain concentrations, duration of staining, and counting strategies, in relation to the types of samples being examined. The high variability in bacterial counts observed within similar sample types may be partially accounted for by differences in methods. Synthesizing review findings, we include a recommended method for the direct enumeration of bacteria in environmental samples.

Bacteria↗
PubMed1994

A study of home care quality management data-collection systems.

A recent study reveals that home care agencies have inconsistent standards for quality management and inefficient data-collection systems. Are currently available data-collection systems suited for home care needs, or should they be redesigned?

Data Collection↗
PubMed1993

Analysis of activated T cell infiltrates in rat renal allografts by gamma camera imaging after injection of 123iodine-interleukin 2.

Activated T cells bearing receptors for interleukin 2 (IL-2) play an important role in immunity and in immunopathological processes such as allograft rejection. In order to investigate the presence of activated T cells in lymphocytic infiltrates in transplanted kidneys, we investigated the uptake and retention of radioactivity after an intravenous injection of radioiodinated IL-2 in experimentally transplanted rats. IL-2 was enzyme radiolabelled with 123iodine using a glucose oxidase/lactoperoxidase method and shown to retain specific binding on an IL-2 receptor positive cell line, C58E6. To examine the kinetics of 123iodine-interleukin 2 (123I-IL-2) uptake in vivo, animals that had been transplanted five days previously with allogeneic or syngeneic grafts were injected with 123I-IL-2 and then imaged using an external gamma camera. Radioactivity was measured at time points up to 240 min after intravenous injection of 123I-IL-2. Four groups of animals were examined: allogeneic grafts (n = 7); syngeneic grafts (n = 6); ischaemic native kidneys (n = 5) all following injection with 123I-IL-2; and allogeneic transplants (n = 5) after injection of 123I-lactalbumin, an irrelevant molecule of similar molecular weight to IL-2. The peak radioactivity after injection was measured and the amount of radioactivity retained in the graft at increasing time intervals after injection was expressed as a function of initial peak radioactivity. At four hours after injection of 123I-IL-2, mean retention of activity by rejecting grafts was 77(+/- 2.68)% of peak activity, compared to 45(+/- 6.38)% in syngeneic controls (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Strategic planning in long-term care organizations.

This article has endeavored to show that strategic planning is applicable to even the smallest, least complex organization. Strategic planning does not have to be, nor should it be, an extra burden foist on an already overworked staff. It can be an important, supportive element of the management process. Inclusion of strategic planning in an organization's routine management practice can help to perpetuate the organization. As one author (Infield 1989) recently noted, "In the current competitive health care environment, strategic planning capabilities may determine the survival of many long-term care programs and services."

Health Facility Administrators↗
PubMed1988

Changes in epilithic communities due to individual and combined treatments of zinc and snail grazing in stream mesocosms.

Effects of 0.5 mg/liter zinc (Zn) and snail grazing (400 snails/m2) on density of dominant algal and protozoan taxa, epilithic glucose respiration, and ash-free dry weight (AFDW) were examined using established (12-day colonization) periphyton communities in flow-through stream mesocosms with four treatments (Zn, snails, Zn and snails, control) for 30 days. Grazing and Zn similarly reduced the abundance of 5 of 10 dominant algal taxa and AFDW during the first 10 days of treatment. Abundance of these taxa and AFDW in grazed (ambient Zn) treatments approached control levels after 10 days as the effect due to snails decreased. Decreasing temperatures may have reduced snail activity. Snails, Zn, and the combination of these treatments contributed to higher rates of glucose respiration per unit AFDW. Protozoan species abundance was reduced to less than half by Zn but was unaffected by snails. Although Zn and snails individually altered structural and functional aspects of this microbial community, the effects when both treatments were combined could not always be inferred from the individual effects. Testing individual and combined variables that affect periphyton with a corresponding assessment of population dynamics, biomass, and community functional attributes will enhance understanding of the overall effects of pollutants on periphyton communities.

Animals↗
PubMedDate not supplied

Field evaluation of predictions of environmental effects from a multispecies-microcosm toxicity test.

The predictive validity of a multispecies-microcosm toxicity test was evaluated. Predictions of biological response to a complex effluent were made from dose-response curves in laboratory tests and compared to observed effects in the receiving system. No effects on protozoan or macroinvertebrate communities were observed at the field site with effluent concentrations less than the chronic value of 1.7% effluent determined in laboratory tests. In addition, the microcosm test accurately predicted the magnitude of decreases in species richness in protozoan and macroinvetebrate communities in the receiving system at the first downstream site. Predictions of environmental effects for stations farther downstream were generally less accurate and too high, perhaps due to lack of persistence in the toxicity of the effluent. Stimulation of total biomass and algal growth were observed in both laboratory and field tests, but laboratory tests greatly overestimated the magnitude of enrichment responses in the receiving system.

Animals↗
PubMedDate not supplied

Strategies for targeting complement inhibitors in ischaemia/reperfusion injury.

A transplanted organ suffers inherently from an ischaemic insult and subsequent reperfusion injury. The severity of such early events is thought to influence the success of the transplant procedure, not only in the immediate post-transplant period, but also to predispose the graft to both acute and chronic rejection. In this paper, we review the influence of the complement system upon ischaemia,reperfusion injury. The recognition of the involvement of complement has led to novel strategies to try to modulate ischaemia/reperfusion injury, some of which we have summarized. Finally, we note our own strategy to target complement inhibition in ischaemic tissues.

Animals↗