Biomedical subjects

Phillip Ruiz

Publications and source records attributed to Phillip Ruiz.

61 records · Page 4Linked to original sources

PubMed2002

Host-derived enterocytes in intestinal grafts.

Replacement of donor lymphoid tissue by lymphocytes of recipient origin is an established phenomenon in small bowel transplants. However, replacement of donor epithelial cells of bowel grafts by host cells has not been demonstrated. The objective of our study was to determine whether donor enterocytes are replaced by host-derived enterocytes in the intestinal allograft. Graft biopsy specimens, obtained from five human male recipients of female intestine, were examined for the presence of male enterocytes. The biopsies dated from 90 to 770 days posttransplant. Formalin-fixed 3-microm specimen sections were stained for X and Y chromosomes by fluorescent in situ hybridization technique. Fluorescent microscopy of the stained sections identified male enterocytes in four patients, with a percentage of male cells ranging from 0.09% to 0.26% of the total enterocyte mass. Using the fluorescent in situ hybridization technique, we demonstrated the presence of host-derived male (XY) enterocytes in the female intestinal graft.

Enterocytes↗

PubMed2002

Temporal relationships between acute cellular rejection features and increased mucosal fibrosis in the early posttransplant period of human small intestinal allografts.

BACKGROUND: Intestinal allograft biopsies limit histopathological analysis to the superficial layers of the bowel. These biopsies allow a reasonable assessment of the histological features of acute rejection, but characteristics of chronic injury in mucosal layers remain poorly defined because of the limitations posed by endoscopic sampling. Experimental work has inferred that intestinal mucosal fibrosis may be indicative of chronic rejection; however, a temporal, graded study of mucosal fibrosis has not been performed. METHODS: A total of 79 endoscopic intestinal allograft biopsies from 12 patients obtained at 3 to 120 days posttransplantation were evaluated. Fibrosis and individual parameters of acute cellular rejection were graded according to a semiquantitative scoring system and were evaluated for potential relationships with each other. RESULTS: We found that while acute rejection tends to occur early in the posttransplant period, fibrosis of the lamina propria increases at a later time, particularly in the third and fourth month. Several individual graded parameters of acute rejection had an association with fibrosis at the same time points. CONCLUSIONS: Fibrous replacement of the lamina propria in human endoscopic allograft biopsies occurs with advancing time after transplantation. Acute rejection precedes and may have some eventual impact upon the amount of fibrosis present. A measurement of the connective tissue component of bowel transplant tissue may serve as a harbinger of long-term enteral allograft dysfunction.

Acute Disease↗

PubMed2002

Burkitt s lymphoma variant of post-transplant lymphoproliferative disease (PTLD).

The occurrence of posttransplant lymphoproliferative disorder (PTLD) in solid organ allograft recipients can be quite varied in clinical presentation, histopathological characteristics and frequency. A variety of lymphomas can develop as a PTLD although some types appear infrequently and remain poorly understood in this clinical setting. In this report, we describe two cases of Burkitt s lymphoma presenting as a PTLD following liver transplantation. The recipients were 12 and 44 years of age and displayed gastrointestinal involvement by the tumors several years following transplant. The tumors displayed the typical histological features of Burkitt s lymphoma and were markedly positive for EBV. The tumors displayed similar immunophenotypic characteristics by flow cytometry and had rearrangements of the immunoglobulin J-H heavy chain. The tumors required aggressive chemotherapy and a cessation of immunosuppressive therapy. This report demonstrates that Burkitt s type lymphomas can develop in the posttransplant setting and that these tumors contain morphologic, cytofluorographic and molecular features identical to Burkitt s lymphomas that occur in non-transplant patients. Our experience is that these PTLD- Burkitt s lymphomas behave aggressively and require intensive chemotherapeutic intervention.

Adult↗

PubMed2002

Absence of donor MHC antigen expression ameliorates chronic kidney allograft rejection.

BACKGROUND: In previous studies, we have demonstrated that a subset of mouse kidney allografts has prolonged survival without any immunosuppressive treatment. Chronic rejection (CR) develops in these long surviving grafts. The pathologic features of CR in this model are similar to CR in human kidney grafts. METHODS: To explore the role of donor major histocompatibility complex (MHC) antigens in the development of CR, we performed vascularized kidney transplants using kidneys from donor mice that lack expression of both MHC class I and II antigens (MHC-/-). RESULTS: Survival was significantly improved in recipients of MHC-/- allografts. This enhanced survival was associated with higher glomerular filtration rate (GFR) in MHC-/- allografts (4.92 +/- 0.54 cc/min/kg) compared to controls (2.19 +/- 0.63 cc/min/kg; P = 0.004). The typical histologic features of CR were markedly reduced in MHC-/- allografts. Semiquantitative histopathological scores for MHC-/- grafts (13.3 +/- 2.1) were significantly lower than in control allografts (19.0 +/- 1.0; P = 0.04). Along with this improvement in structural abnormalities, significantly fewer CD4+ T (38.3 cells/mm(2) vs. 75.0 cells/mm(2); P = 0.008), CD8+ T cells (38.7 vs. 96 cells/mm(2), respectively; P = 0.008) and macrophages (60 vs. 134 cells/mm(2), respectively; P = 0.04) infiltrated MHC-/- allografts compared to controls. The levels of intragraft cytokine mRNA expression also were reduced in MHC-/- allografts compared to control allografts. Finally, serum alloantibodies were virtually undetectable in recipients of MHC-/- kidney allografts. CONCLUSIONS: Cell surface expression of donor MHC antigens promotes the development of CR. Donor antigen expression promotes the accumulation of infiltrating cells in the graft and the development of donor specific alloantibodies. Abrogation of these responses is associated with improved graft survival and reduced CR in MHC-/- grafts.

Animals↗

PubMed2001

Intestinal and multivisceral transplantation.

Intestinal transplantation has been gradually instituted in the management of intestinal failure. More than 200 cases including isolated intestinal transplant, liver/intestinal transplant, and multivisceral transplant have been performed worldwide,with 1-year graft and patient survival rates of 66% and 54%,respectively. Indications for the procedure include short bowel syndrome and functional abnormalities secondary to a variety of diseases or conditions. Tacrolimus-based immunosuppression regimens have been used universally with improved outcomes. The major contributors to the morbidity and mortality include rejection,infection, and technical complications. Of those, control of rejection remains the most difficult dilemma and it will be the key to improved patient and graft survival.

Digestive System Surgical Procedures↗

PubMedDate not supplied

Impact of a selenium chemoprevention clinical trial on hospital admissions of HIV-infected participants.

PURPOSE: To evaluate the impact of selenium chemoprevention (200 microg/day) on hospitalizations in HIV-positive individuals. METHOD: Data were obtained from 186 HIV+ men and women participating in a randomized, double-blind, placebo-controlled selenium clinical trial (1998-2000). Supplements were dispensed monthly, and clinical evaluations were conducted every 6 months. Inpatient hospitalizations, hospitalization costs, and rates of hospitalization were determined 2 years before and during the trial. RESULTS: At enrollment, no significant differences in CD4 cell counts or viral burden were observed between the two study arms. Fewer placebo-treated participants were using antiretrovirals (p <.05). The total number of hospitalizations declined from 157 before the trial to 103 during the 2 year study. A marked decrease in total admission rates (RR = 0.38; p =.002) and percent of hospitalizations due to infection/100 patients for those receiving selenium was observed (p =.01). As a result, the cost for hospitalization decreased 58% in the selenium group, compared to a 30% decrease in the placebo group (p =.001). In the final analyses, selenium therapy continued to be a significant independent factor associated with lower risk of hospitalization (p =.001). CONCLUSION: Selenium supplementation appears to be a beneficial adjuvant treatment to decrease hospitalizations as well as the cost of caring for HIV-1-infected patients.

Adult↗

PubMedDate not supplied

Cytofluorographic identification of activated T-cell subpopulations in the semen of men with spinal cord injuries.

The semen of most men with spinal cord injury (SCI) contains an abundance of leukocytes. It is not known if this leukocytospermia contributes to the abnormally low sperm motility observed in many of these men. Our study used flow cytometry to identify the leukocyte population in the semen of 12 men with SCI compared to 8 healthy age-matched control subjects. The results showed that, compared to control subjects, the semen of men with SCI had increased numbers of mature granulocytes and lymphocytes. The largest proportion of the leukocytes consisted of lymphocytes, and immunophenotypic analysis showed that the greater fraction were T cells, many of which coexpressed human leukocyte antigen HLA-DR and CD25, suggesting they were in an "activated" state. No significant B-cell population was evident. Our finding of immunologically active leukocytes is a significant step in understanding the relationship of leukocytospermia and decreased sperm motility in the semen of men with SCI.

Adult↗