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Biomedical subjects

P Ruiz

Publications and source records attributed to P Ruiz.

At least 127 records · Page 7Linked to original sources
PubMed1999

Ethnic differences in the neuroleptic treatment of schizophrenia.

Ethnic differences in psychopharmacological treatment have received much attention in the last two decades. Most of the research efforts conducted so far in the field of ethnopsychopharmacology have focused on comparative responses to neuroleptics and lithium between white and Asian-American patients, and on comparative responses to tricyclic antidepressants among white, African-American and Hispanic patients. In this article we focus on the response to neuroleptic treatment among white, African-American and Hispanic patients suffering from schizophrenia. Our findings suggest that Hispanic patients need lower doses of neuroleptics than white or African-American patients to attain a similar response in the treatment of schizophrenia. Additionally, our study suggests that, if weight is taken to consideration, African-American patients need the same dose of neuroleptics as do white patients in order to attain a similar response in the treatment of schizophrenia. Further studies are suggested to confirm our findings.

Acute Disease↗
PubMed1999

Correlation between allograft survival and chimeric state after bone marrow infusion in rat small bowel transplantation.

Methods to enhance natural microchimerism, which occurs after any successful organ transplant, are currently explored using unmodified donor bone marrow both in experimental and in clinical trials. Because of the potential immunomodulatory effects of donor bone marrow cells, we performed this study to evaluate the effect of single and multiple donor-specific bone marrow infusions (DSBMI) on chimerism and small bowel allograft survival in a fully histoincompatible rat model. Forty-five male DA rats and 45 female Lewis rats were used as donors and recipients, respectively, for a heterotopic small bowel transplant. Animals were separated into 10 groups according to the number of bone marrow infusions and immunosuppressive protocol used. Control groups (groups 1 and 2) did not receive any bone marrow infusion, groups 3 and 4 received one infusion at day 0 (150 x 10(6) cells), groups 5 and 6 received two infusions at days 0 and 4 (75 x 10(6) cells each), groups 7 and 8 received two infusions at days 4 and 10 (75 x 10(6) cells each), and groups 9 and 10 received five infusions at days 4, 10, 15, 20 and 25 (30 x 10(6) cells each). Animals in groups 1, 3, 5, 7 and 9 were immunosuppressed with 0.5 mg/kg FK506 while the remaining groups were immunosuppressed with 1 mg/kg FK506, from day 0 to 4 after transplant. Every 15 days, the chimeric state was determined by flow cytometry in order to detect cells expressing DA rat class I antigen, and small bowel biopsies were obtained from ileostomies. Animals in all groups showed minimal to moderate acute rejection at day 15 after transplant, however, vascular rejection (vasculitis, arteritis) was observed in only bone marrow groups (100% in 0.5 mg/kg and 42.1% in 1 mg/kg FK506 groups). On day 30, 58.3% of bone-marrow-infused animals and 66.6% of controls showed severe acute and early chronic rejection. The chimeric levels varied from 0 to 12% after transplant and were significantly higher in bone-marrow-infused groups compared with controls (p < 0.05). We conclude that modulation of immune response with short-course immunosuppression and a single or multiple DSBMI did not improve allograft or recipient survival. The inability to achieve a stable chimeric state did not allow us to determine the effect of chimerism on graft and recipient survival after small bowel transplantation.

Animals↗
PubMed1999

Inclusion of entire pancreas in the composite liver and intestinal graft in pediatric intestinal transplantation.

An entire pancreatico-duodenal complex was included in the liver and intestinal graft in eight children who received small-size grafts. This method showed several advantages compared to the traditional approach. They included reducing time for graft preparation by eliminating donor pancreas resection, no necessity of biliary reconstruction and leaving natural tissue support for blood vessels. The method was not associated with an increased risk of complications such as pancreatitis or rejection. It should be considered in pediatric liver and intestinal transplant recipients who require small-size grafts.

Age Factors↗
PubMed1999

Mental health care for Hispanic Americans: a current perspective.

In this article, the authors review patterns and challenges in the conceptualization, implementation, and academic support of the mental health services of Hispanic Americans. A critical analysis was conducted on information obtained through manual and computerized searches of published literature and conference reports. New clinical care approaches include the DSM-IV's cultural formulation with its complement of standardized multiaxial diagnosis, integration of services across clinical disorders or conditions and across sources of care, as well as pluralistic criteria and judges for service outcome appraisal. Emerging clinical approaches offer an opportunity to enhance the mental health care of Hispanic Americans within an increasingly multicultural U.S. society.

Attitude to Health↗
PubMed1999

Chronic rejection of mouse kidney allografts.

BACKGROUND: Chronic renal allograft rejection is the leading cause of late graft failure. However, its pathogenesis has not been defined. METHODS: To explore the pathogenesis of chronic rejection, we studied a mouse model of kidney transplantation and examined the effects of altering the expression of donor major histocompatibility complex (MHC) antigens on the development of chronic rejection. RESULTS: We found that long-surviving mouse kidney allografts develop pathological abnormalities that resemble chronic rejection in humans. Furthermore, the absence of MHC class I or class II antigens did not prevent the loss of graft function nor alter the pathological characteristics of chronic rejection. Expression of transforming growth factor-beta (TGF-beta), a pleiotropic cytokine suggested to play a role in chronic rejection, was markedly enhanced in control allografts compared with isografts. However, TGF-beta up-regulation was significantly blunted in MHC-deficient grafts. Nonetheless, these differences in TGF-beta expression did not affect the character of chronic rejection, including intrarenal accumulation of collagens. CONCLUSIONS: Reduced expression of either class I or II direct allorecognition pathways is insufficient to prevent the development of chronic rejection, despite a reduction in the levels of TGF-beta expressed in the allograft. This suggests that the severity of chronic rejection is independent of the level of MHC disparity between donor and recipient and the level of TGF-beta expression within the allograft.

Animals↗
PubMed1999

Clinical relevance of contemporary cultural psychiatry.

In recent years, the field of cultural psychiatry has gained recognition and accumulated evidence of its clinical relevance. This article examines the intersections of culture and psychopathology and describes five independent but interrelated clinical dimensions that identify and define culture as: a) an interpretive/explanatory tool, b) a pathogenic/pathoplastic agent, c) a diagnostic/nosological factor, d) a therapeutic/protective element, and e) a service/management instrument. Along these lines, conceptual boundaries, clinical findings, specific applications, and research implications for each of the five dimensions are systematically reviewed. Cultural psychiatry adds significantly to the comprehensiveness of psychiatric evaluation and management and addresses prominent issues regarding understanding, classification, diagnosis, and competent treatment of most psychiatric disorders in every society and region of the world. Based on the strength of these clinical dimensions, and on the related educational and research efforts, cultural psychiatry can also contribute decisively to the design of comprehensive mental health policies.

Cultural Characteristics↗
PubMed1999

Angiotensin II regulates cellular immune responses through a calcineurin-dependent pathway.

The renin-angiotensin system (RAS) is a key regulator of vascular tone and blood pressure. In addition, angiotensin II also has a number of cellular effects that may contribute to disease pathogenesis. Using Agtr1a(-/-) mice, which lack AT(1A) receptors for angiotensin II, we have identified a novel function of the RAS to modulate the immune system. We find that angiotensin II, acting through type 1 (AT(1)) receptors on immune cells, triggers the proliferation of splenic lymphocytes. These actions contribute to the vigor of cellular alloimmune responses. Within lymphoid organs, sufficient components of the RAS are present to activate AT(1) receptors during an immune response, promoting cell growth. These actions require activation of calcineurin phosphatase. In an in vivo model of cardiac transplantation, the absence of AT(1) signaling accentuates the immunosuppressive effects of the calcineurin inhibitor cyclosporine. We conclude that inhibition of AT(1) receptor signaling should be useful as an anti-inflammatory and immunosuppressive therapy. Furthermore, the actions of the RAS to promote lymphocyte activation may contribute to inflammation that characterizes a number of diseases of the heart and the vascular system.

Angiotensin II↗
PubMed1999

Training family practice residents in psychiatry: an ambulatory care training model.

OBJECTIVE: To demonstrate the importance of providing psychiatric training to primary care practitioners in ambulatory care settings. Additionally, to describe the model used for this purpose in the Department of Psychiatry and Behavioral Sciences of the University of Texas Medical School at Houston in order to further stimulate educational opportunities on this topic. METHOD: A review of the psychiatric curriculum offered to family practice residents during their PGY-2 year one-month rotation in psychiatry at the University of Texas Mental Sciences Institute is provided. Emphasis is given to key areas of the curriculum such as: knowledge, skills, and attitude development. Special focus on the clinical and educational experiences is also offered for the purpose of providing unique perspectives about the curriculum methodology. RESULTS: The careful assessment of the feedback obtained from the family practice residents who were exposed to this ambulatory training model demonstrates that this type of setting was satisfactory for the teaching of psychiatry to primary care residents. CONCLUSIONS: Primary care residents have always treated a large number of psychiatric patients. Given the current status of our health care system, primary care practitioners should have even a greater role in the future delivery of psychiatric services. In this article, we offer a model of training for primary care residents in psychiatry, which emphasize cost-effectiveness, high quality of care, and ambulatory care settings.

Academic Medical Centers↗
PubMed1999

Long-term survival and function of intrahepatic islet allografts in baboons treated with humanized anti-CD154.

Clinical islet cell transplantation has resulted in insulin independence in a limited number of cases. Rejection, recurrence of autoimmunity, and impairment of normal islet function by conventional immunosuppressive drugs, e.g., steroids, tacrolimus, and cyclosporin A, may all contribute to islet allograft loss. Furthermore, intraportal infusion of allogeneic islets results in the activation of intrahepatic macrophages and endothelial cells, followed by production of proinflammatory mediators that can contribute to islet primary nonfunction. We reasoned that the beneficial effects of anti-CD154 treatment on autoimmunity, alloreactivity, and proinflammatory events mediated by macrophages and endothelial cells made it an ideal agent for the prevention of islet allograft failure. In this study, a nonhuman primate model (Papio hamadryas) was used to assess the effect of humanized anti-CD154 (hu5c8) on allogeneic islet engraftment and function. Nonimmunosuppressed and tacrolimus-treated recipients were insulin independent posttransplant, but rejected their islet allografts in 8 days. Engraftment and insulin independence were achieved in seven of seven baboon recipients of anti-CD154 induction therapy administered on days -1, 3, and 10 relative to the islet transplant. Three of three baboons treated with 20 mg/kg anti-CD154 induction therapy experienced delayed rejection episodes, first detected by elevations in postprandial blood glucose levels, on postoperative day (POD) 31 for one and on POD 58 for the other two. Re-treatment with three doses of anti-CD154 resulted in reversal of rejection in all three animals and in a return to normoglycemia and insulin independence in two of three baboons. It was possible to reverse multiple episodes of rejection with this approach. A loss of functional islet mass, as detected by reduced first-phase insulin release in response to intravenous glucose tolerance testing, was observed after each episode of rejection. One of two baboons treated with 10 mg/kg induction therapy became insulin independent post-transplant but rejected the islet graft on POD 10; the other animal experienced a reversible rejection episode on POD 58 and remained insulin independent and normoglycemic until POD 264. Two additional baboon recipients of allogeneic islets and donor bone marrow (infused on PODs 5 and 11) were treated with induction therapy (PODs -1, 3, 10), followed by initiation of monthly maintenance therapy (for a period of 6 months) on POD 28. Rejection-free graft survival and insulin independence was maintained for 114 and 238 days, with preservation of functional islet mass observed in the absence of rejection. Prevention and reversal of rejection, in the absence of the deleterious effects associated with the use of conventional immunosuppressive drugs, make anti-CD154 a unique agent for further study in islet cell transplantation.

Animals↗
PubMed1999

Discriminant variables between organ donors and nondonors: a post hoc investigation.

CONTEXT: Few studies in organ donation have focused on the attitudes and opinions of families who were asked to donate the organs of a deceased relative. OBJECTIVE: To determine what variables influenced a family's decision to donate. DESIGN: Post hoc investigation using a survey. SETTING: Málaga, Spain. PARTICIPANTS: Seventy-one people who had been approached for the donation of their deceased relatives' organs at a single hospital. MAIN OUTCOME MEASURE: Consent to donate. RESULTS: Based on a stepwise discriminant function analysis, the following variables played a determining role in a family member's decision to donate: (1) the expressed wish of the deceased, (2) having a clear understanding of the definition of "brain death." (3) the manners and approach of the doctors, (4) the hospital facilities, (5) concerns regarding the donation process, and (6) educational level. CONCLUSION: Prodonation campaigns geared toward the public and hospital staff should focus on specific objectives to increase the likelihood of consent for organ donation.

Adult↗
PubMed1998

Efficacy of lamivudine in controlling hepatitis B virus recurrence after liver transplantation.

BACKGROUND: Indication of liver transplantation for patients infected with hepatitis B virus (HBV) remains controversial because of the high incidence of posttransplant HBV recurrence and aggressive involvement of the allograft. In this article, we provide evidence that the introduction of lamivudine may favorably alter the prognosis of these patients. METHODS: Lamivudine was used in 40 HBV-infected adult patients suffering from chronic end-stage liver disease who underwent liver transplantation. The drug was used in the following settings: failure of prolonged passive immunoprophylaxis, elective conversion from immunoprophylaxis, de novo posttransplant HBV infection, and primary treatment with lamivudine which started before and continued after transplantation. Twenty patients (50%) had viral replication at the time lamivudine was started. Posttransplant and antiviral treatment follow-ups were 8-64 months (median follow-up: 27.5 months) and 9-39 months (median follow-up: 19 months), respectively. RESULTS: The patient and graft survival rates were 97.5% (39/40). Thirty-three patients (82.5%) have remained free of viral recurrence. In the seven re-infected patients, the manifestations of HBV involvement of the allograft have been mild. There have been no side effects related to lamivudine, and the treatment is substantially less costly than with other anti-HBV agents. CONCLUSIONS: Compared with historic series utilizing other modalities of treatment, the use of lamivudine has, so far, yielded superior results. This drug may be an important acquisition for antiviral prophylaxis in HBV-infected liver recipients. Because of the risk of viral mutations, however, efforts should proceed to achieve more efficacious methods for prevention and control of HBV recurrence.

Adult↗
PubMed1998

The inductive properties of mesoderm suggest that the neural crest cells are specified by a BMP gradient.

We have analyzed the role of mesoderm in the induction of the neural crest in Xenopus using expression of neural plate (Xsox-2) and neural crest (Xslug and ADAM). Conjugation experiments using different kinds of mesoderm together with embryonic dissection experiments suggest that the dorsolateral mesoderm is capable of specifically inducing neural crest cells. Neural crest markers can be induced in competent ectoderm at varying distances from the inducing mesoderm, with dorsal tissue inducing neural crest at a distance while dorsolateral tissue only induces neural crest directly in adjacent ectoderm. The results suggest that dorsal mesoderm has a high level of inducer and dorsolateral mesoderm has a lower level, consistent with a inductive gradient. We explored the possible role of BMP and noggin in the generation of such a hypothetical gradient and found that: (1) progressively higher levels of BMP activity are sufficient for the specification of neural plate, neural crest, and nonneural cells, respectively; (2) progressively higher levels of noggin are able to induce neural crest at greater distances from the source of inducer; and (3) modification of the levels of BMP activity causes induction of the neural crest in absence of neural plate, suggesting independent induction of these two tissues. We propose a model in which a gradient of BMP activity is established in the ectoderm by interaction between BMP in the ectoderm and BMP inhibitors in the mesoderm. Neural crest is induced when a threshold level of BMP is attained in the ectoderm. The dorsolateral mesoderm produces either BMP inhibitors or a specific neural crest inducer, with low BMP activity inducing neural plate while high BMP activity induces epidermis.

Animals↗
PubMed1998

CD26 expression and dipeptidyl peptidase IV activity in an aggressive hepatosplenic T-cell lymphoma.

The transmembrane serine aminopeptidase dipeptidyl peptidase IV (DPP IV) (also known as CD26) participates in several immunological functions and has a binding affinity for several molecules, including collagen, which may be an integral mechanism for T cells to traverse endothelial barriers. Since CD26 is phenotypically expressed in certain T-cell malignancies, this study utilized a novel four-color cytofluorographic procedure to measure DPP IV enzymatic activity concurrently with the expression of other surface markers in an aggressive hepatosplenic T-cell lymphoma. Immunophenotypic analysis by flow cytometry revealed the tumor to be CD2+, CD3+, CD5-, CD7+, TcR-gamma/delta+, CD4-, CD8+/-, CD56+, and CD11c+. The CD26 molecule was also expressed, and DPP IV activity was present, with the maximal activity detectable after 10 min of incubation. These results represent the initial description of enzymatically active CD26 in a T-cell malignancy, and raise the possibility that this molecule may be a participant in the pathogenetic mechanisms utilized by the neoplastic cells.

Adolescent↗
PubMed1998

Human thymocyte dipeptidyl peptidase IV (CD26) activity is altered with stage of ontogeny.

The nonintegrin receptor CD26, also known as dipeptidyl peptidase IV (DPP IV) is a transmembrane 110- to 120-kDa serine aminopeptidase glycoprotein with multiple functions, including cellular trafficking through extracellular matrix, and costimulatory potential during T cell activation, and is an influence upon T cell differentiation during their maturation in the thymus. In order to further define the expression and functional activity of this membrane exopeptidase in human thymus, we utilized a nondisruptive, cytofluorogenic assay which allowed simultaneous measurement of intracellular DPP IV activity using a fluorochrome-conjugated peptide substrate with surface staining of plasma membrane-associated T lymphocyte lineage antigens CD4 and CD8, as well as CD26. Human thymi were examined using the three-color assay, and significant differences in time-dependent DPP IV activity were found among the thymocyte subsets defined by their CD4/CD8 phenotype. In this regard, CD4(-)/CD8(-) thymocytes displayed the lowest DPP IV activity and had higher activity than the smaller-sized CD26(+) cells. Thymocytes containing greater percentages of apoptotic cells expressed lower DPP IV activity than viable cells. Thus, DPP IV appears to be upregulated as thymocytes mature and is reduced among thymocyte populations enriched for cells undergoing programmed cell death, suggesting that CD26-associated enzymatic activity is ontogenically controlled during T cell maturation and may be involved in thymic deletion of emerging clones.

Apoptosis↗
PubMed1998

Peripheral human T lymphocyte maintenance of immune functional capacity and phenotypic characteristics following in vivo cocaine exposure.

The effects of cocaine exposure upon the host's immune response is equivocal since a variety of studies have generated conflicting conclusions, often as the result of differences between in vitro and/or animal models and the actual conditions experienced in humans who are acutely abusing this drug. To further address this issue, we have studied a group of patients who were positive for cocaine or cocaine metabolites and we evaluated a variety of functional parameters of T-lymphocytes and other peripheral lymphoid cell populations, as well as immunophenotypic characteristics of these cells. When compared to normal controls and patients who were negative for cocaine, we found that the cocaine-positive patients had T-cell functional assays which were essentially normal, with the exception of a slight depression in PHA stimulation. Likewise, the immunophenotype of the peripheral blood lymphocytic populations showed normal percentages and numbers of their T cell subsets (CD4, CD8), NK cells, and B cells. Multicolor flow cytometry analysis revealed no difference in T cell subpopulations positive for the "memory" marker, CD62L. No correlation could be established between levels of cocaine or cocaine metabolites and any phenotypic, demographic, or functional parameter. In summary, these results demonstrate that individuals acutely exposed to cocaine do not show markedly altered T cell function or fluctuations in phenotypically identified cell populations. These studies imply that acute cocaine exposure does not predispose individuals to grossly apparent immunosuppression. However, the possibility that subtle, transient, or more specific changes in the immune system may be incurred by use of cocaine, particularly with chronic exposure, remains to be determined.

Adult↗
PubMed1998

Treatment with progesterone analogues decreases macrophage Fcgamma receptors expression.

Macrophage Fcgamma receptors (FcgammaRs) are critical for host defense against infection and have an important role in immune cytopenias. Modulation of macrophage FcgammaRs expression is a potential therapeutic approach to immune disorders. Glucocorticoids and synthetic progesterone analogues decrease macrophage FcgammaRs expression. We assessed the effect of treatment with commonly employed progestins on the expression of macrophage FcgammaRs using an experimental model in the guinea pig. Eight clinically available progesterones, medroxyprogesterone acetate (P3), megestrol acetate (P4), medrogestone (P5), alylestrenol (P6), linestrenol (P7), didrogesterone (P8), norethisterone (P9), and gestonorone caproate (P10) and two endogenous progesterones, progesterone (P1) and 17 alpha-hydroxyprogesterone (P2), were studied. Following in vivo treatment of guinea pigs, we determined the clearance of IgG-sensitized erythrocytes in vivo, the binding of IgG-sensitized erythrocytes by isolated splenic macrophages, and splenic macrophage Fcgamma receptor cell surface expression. All progesterones impaired the clearance of IgG-sensitized erythrocytes by decreasing splenic macrophage Fcgamma receptor expression. P5, P6, P7, and P8 were less effective. Flow cytometry and fluorescence microscopy with monoclonal antibodies demonstrated that progesterones decreased the cell surface expression of FcgammaR2 more than that of FcgammaR1,2. Clinically employed progestins impair the clearance of IgG-coated cells by decreasing splenic macrophage FcgammaRs expression. Thus, progesterones are candidate drugs for the treatment of immune disorders.

Animals↗