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Biomedical subjects

X Cai

Publications and source records attributed to X Cai.

At least 199 records · Page 11Linked to original sources
PubMed1992

Antipeptide antibodies that can distinguish specific subunit polypeptides of glutamine synthetase from bean (Phaseolus vulgaris L.).

The amino acid sequences of the beta and gamma subunit polypeptides of glutamine synthetase from bean (Phaseolus vulgaris L.) root nodules are very similar. However, there are small regions within the sequences that are significantly different between the two polypeptides. The sequences between amino acids 2 and 9 and between 264 and 274 are examples. Three peptides (gamma 2-9, gamma 264-274, and beta 264-274) corresponding to these sequences were synthesized. Antibodies against these peptides were raised in rabbits and purified with corresponding peptide-Sepharose affinity chromatography. Western blot analysis of polyacrylamide gel electrophoresis of bean nodule proteins demonstrated that the anti-beta 264-274 antibodies reacted specifically with the beta polypeptide and the anti-gamma 264-274 and anti-gamma 2-9 antibodies reacted specifically with the gamma polypeptide of the native and denatured glutamine synthetase. These results showed the feasibility of using synthetic peptides in developing antibodies that are capable of distinguishing proteins with similar primary structures.

Amino Acid Sequence↗
PubMed1992

Nitric oxide production in host-versus-graft and graft-versus-host reactions in the rat.

The present study was designed to determine whether .N = O produced in vivo during the rejection of histoincompatible tissues might permit serum NO2-/NO3- levels to serve as markers of a rejection reaction. Rat syngeneic and allogeneic liver, heart, bone marrow/spleen cell, small bowel, skin, and sponge matrix grafts were performed and the stable end-products of .N = O, NO2-/NO3-, were serially assayed in the serum of the grafted animals. A significant rise of serum NO2-/NO3- levels in the allografted animals preceded the onset of clinical signs of rejection or graft-versus-host disease, with the exception of the skin and sponge matrix graft models, where elevated serum NO2-/NO3- levels were never observed. In all transplant models, normal serum NO2-/NO3- levels were observed at all times in animals that received syngeneic grafts. Furthermore, treatment of allograft recipients with the immunosuppressive agents FK 506 or cyclosporine A inhibited .N = O production. Determination of serum creatinine levels demonstrated that the elevated serum NO2-/NO3- levels were not caused by kidney dysfunction. Serum NO2-/NO3- levels might be useful early serum markers of the initiation of a rejection reaction or graft-versus-host disease when functional markers of graft dysfunction are not apparent.

Animals↗
PubMed1992

[Relationship between different patterns of left ventricular hypertrophy and plasma norepinephrine and hemorheology in patients with essential hypertension].

The changes of plasma norepinephrine (NE) concentration and hemorheology in 60 patients with essential hypertension (EH) with different patterns of left ventricular hypertrophy (LVH) were observed. The results showed that a higher value in whole blood viscosity (WBV) at a shear rate of 230-s was found in concentric hypertrophy (CH) group; a significant increase in plasma NE was found in asymmetric septal hypertrophy (ASH) group. It suggests that CH appear to be a compensation adapting to the increase in afterload. Significant increase in plasma NE concentration may play an important role in the development of ASH in addition to the afterload.

Adult↗
PubMed1992

Antihistamine effect of supplemental ascorbic acid and neutrophil chemotaxis.

Renewed interest in the antihistamine action of ascorbic acid has emerged with the recently recognized immunosuppressive role of histamine. We examined the antihistamine effect of acute and chronic vitamin C (VC) administration and its effect on neutrophil chemotaxis in healthy men and women. In the chronic study, 10 subjects ingested a placebo during weeks 1, 2, 5 and 6, and 2 g/day of VC during weeks 3 and 4. Fasting blood samples were collected after the initial 2-week period (baseline) and at the end of weeks 4 and 6. Plasma ascorbate rose significantly following VC administration compared to baseline and withdrawal values. Neutrophil chemotaxis rose 19% (NS) during VC administration, and fell 30% after VC withdrawal, but these changes were not correlated to plasma ascorbate levels (r = 0.01). Chemotaxis was inversely correlated to blood histamine (r = -0.32, p = 0.045), and, compared to baseline and withdrawal values, histamine levels were depressed 38% following VC supplementation. Blood histamine and neutrophil chemotaxis did not change 4 hours following a single 2 g dose of ascorbic acid, although plasma ascorbate rose 150%. These data indicate that VC may indirectly enhance chemotaxis by detoxifying histamine in vivo.

Adult↗
PubMed1991

Prevention of graft-versus-host disease following allogeneic bone marrow transplantation in rats using FK506.

FK506 and cyclosporine were used for the prevention of acute graft-versus-host disease. Acute GVHD was induced in Lewis rats by total-body irradiation and subsequent reconstitution with allogeneic (ACI) bone marrow and spleen cells (BMTx). GVHD was assessed by both clinical and histologic parameters during the experiment duration of 60 days, and longer for selected animals. All untreated BM recipients died within 26 days from severe acute GVHD. GVHD was prevented with CsA during the period of immunosuppressive therapy, but it appeared within a few days afterward. FK506-treated BM recipients were also protected, but they had a markedly prolonged GVHD-free period after therapy was discontinued. Most such animals eventually developed GVHD but with notable exceptions. Maintenance therapy with doses of FK506 as low as 0.1 mg/kg every other day (1/20 of daily induction dose) was infallible insurance against delayed GVHD. The relevance of these findings to GVHD caused by lymphoid-containing solid organs such as the intestine was discussed.

Animals↗
PubMed1991

Immunocytochemical Localization of Glutamine Synthetase in Organs of Phaseolus vulgaris L.

Glutamine synthetase was localized in nodules, roots, stems, and leaves of red kidney bean (Phaseolus vulgaris L.) by immunocytochemistry. Affinity purified antibodies reactive with glutamine synthetase were prepared using purified nodule-enhanced glutamine synthetase. Immunogold labeling was observed in the cell cytoplasm in each plant organ. In nodules, the labeling was more intense in the infected cells than in the uninfected cells. No labeling was observed in nodule bacteroids, peribacteroid spaces, or in peribacteroid membranes, while previous reports of glutamine synthetase immunolabeling of legume nodules showed labeling in the bacteroid fraction. Significant labeling was observed in nodule proplastids which contained starch granules. Substantial labeling was also observed in leaf chloroplasts. No labeling was observed in other organelles including mitochondria, peroxisomes, and endoplasmic reticulum. Preimmune IgGs did not bind to any structure in the tissues examined.

Journal Article↗
PubMed1991

FK 506 reverses acute graft-versus-host disease after allogeneic bone marrow transplantation in rats.

Severe graft-versus-host disease was induced by transplantation of ACI rat bone marrow and spleen cells into irradiated Lewis rat recipients. Treatment with FK 506 or cyclosporine A (CsA) was started after clinical and histologic evidence of acute GVHD was present. A 14-day course of FK 506 at 1.0 mg/kg/day could rescue 100% of the animals suffering from GVHD. In contrast only one half of the animals treated with CsA at a high dose of 25 mg/kg/day recovered. After cessation of immunosuppressive therapy, FK 506-treated animals displayed a marked prolonged disease-free interval as compared to CsA-treated bone marrow recipients. Recurrence of the disease in these animals could be prevented when FK 506 treatment was continued after the induction period with a low maintenance dose of 0.1 mg/kg/day every other day.

Acute Disease↗
PubMed1990

The use of FK-506 for small intestine allotransplantation. Inhibition of acute rejection and prevention of fatal graft-versus-host disease.

Small intestine allotransplantation in humans is not yet feasible due to the failure of the current methods of immunosuppression. FK-506, a powerful new immunosuppressive agent that is synergistic with cyclosporine, allows long-term survival of recipients of cardiac, renal, and hepatic allografts. This study compares the effects of FK-506 and cyclosporine on host survival, graft rejection, and graft-versus-host-disease in a rat small intestine transplantation model. Transplants between strongly histoincompatible ACI and Lewis (LEW) strain rats, and their F1 progeny are performed so that graft rejection alone is genetically permitted (F1----LEW) or GVHD alone permitted (LEW----F1) or that both immunologic processes are allowed to occur simultaneously (ACI----LEW). Specific doses of FK-506 result in prolonged graft and host survival in all genetic combinations tested. Furthermore, graft rejection is prevented (ACI----LEW model) or inhibited (rejection only model) and lethal acute GVHD is eliminated. Even at very high doses, cyclosporine did not prevent graft rejection or lethal GVHD, nor did it allow long-term survival of the intestinal graft or the host. Animals receiving low doses of cyclosporine have outcomes similar to the untreated control groups. No toxicity specific to FK-506 is noted, but earlier studies by other investigators suggest otherwise.

Animals↗