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P Stock

Publications and source records attributed to P Stock.

At least 19 recordsLinked to original sources
PubMed2006

Sequence characterization and expression patterns of defensin and lysozyme encoding genes from the gut of the reduviid bug Triatoma brasiliensis.

The cDNAs encoding an intestinal defensin (def1) and lysozyme (lys1) of the reduviid bug Triatoma brasiliensis have been amplified by PCR using specific oligonucleotide primers and 5'- and 3'-RACE, cloned and sequenced. The 576 bp clone has an open reading frame of 282 bp and encodes a pre-prodefensin with 94 amino acid residues, containing a putative signal and activation peptide cleavage site at Ser19 and Arg51, respectively. The genomic DNA contains a second defensin gene with similar characteristics, 88.3% identity and also one intron of 107 nucleotides. The 538 bp clone has an open reading frame of 417 bp, encoding a pre-lysozyme with 139 amino acid residues. The putative signal peptide is cleaved at alanine 18. Using whole mount in situ hybridization, high expression of both genes has been found, distributed uniformly throughout the entire cardia and the blood-storing stomach and to a much lower extent in the digesting small intestine. Using quantitative real-time PCR, the expression level of def1 was also shown to be very low in small intestine, rectum and salivary glands; in the stomach, expression was 500-2500 times higher than in the cardia and fat body. No expression of lys1 could be detected in the salivary glands and rarely a very low expression in the small intestine, rectum and fat body. Lys1 expression in the stomach was 60-300 times higher than in the cardia. Comparing the levels in unfed fifth instars and up to 15 days after feeding, a strong def1 induction was evident in the fat body at 15 days after feeding and in the stomach a maximum level of def1 and lys1 at 5 days after feeding.

Amino Acid Sequence↗
PubMed2005

Pretransplant islet culture: a comparison of four serum-free media using a murine model of islet transplantation.

INTRODUCTION: Human islet transplant protocols frequently incorporate a brief period of islet culture before transplantation. The optimal medium for pretransplant islet culture is unknown. METHODS: We compared four serum-free media formulated for human islets: Miami (MM1), Memphis (M-SFM), Edmonton (EDM), and hCell OCZEM-SF/AF (hCell). Islets isolated from a single human pancreas with purity >80% were cultured in 2500-islet-equivalent (IE) fractions using the media listed. After 7 days, each 2500-IE fraction was grafted under the kidney capsule of a streptozocin-diabetic rag1 mouse (n = 4 per group). Mice were evaluated with serum glucose monitoring, stimulated C-peptide release, and glucose tolerance tests. Islet fractions transplanted immediately after isolation (n = 4 mice) served as controls. In vitro islet function was assessed on days 0 and 3 and included insulin release (after static glucose stimulation), total cellular C-peptide content, cell count, and viability. RESULTS: Glucose control was improved in all cohorts of mice after transplant, but only islet grafts cultured in MM1 were statistically indistinguishable from fresh islets. MM1- and hCell-cultured islet grafts showed improved glucose tolerance compared with fresh islets; C-peptide release was similar among the four cohorts. In vitro, only islets cultured in MM1 had similar stimulation index to fresh islets, whereas only hCell- and MM1-cultured islets demonstrated recovery of C-peptide content and insulin release. CONCLUSIONS: Media choice before transplant can influence islet quality, even when culture periods are short. Miami MM1 and hCell media may provide better islet protection than alternative media.

Animals↗
PubMed2004

Experience with steroid-free maintenance immunosuppression in simultaneous pancreas-kidney transplantation.

INTRODUCTION: Steroid avoidance is possible in simultaneous pancreas-kidney transplantation with the use of newer immunosuppressive agents and induction therapy. We undertook a retrospective consecutive case review of patients treated at a university tertiary referral center. METHODS: Medical records of 44 consecutive patients receiving a pancreas-kidney transplant from November 2000 to September 2002 were reviewed. The immunosuppression protocol used in this series of patients consisted of thymoglobulin induction, combined with mycophenolate mofetil, tacrolimus, and sirolimus for maintenance immunosuppression. Steroids were used only while thymoglobulin was given and were typically discontinued by postoperative week 1. Main outcome measures included graft and patient survival rates, rejection rates of the kidney or pancreas, infection rates, and surgical complication rates. RESULTS: All 44 patients received a kidney-pancreas transplant with systemic venous anastomosis and enteric drainage of the pancreas. Patient kidney, and pancreas survival rates were 95.6%, 93.2%, and 88.7%, respectively. Biopsy-proven pancreas rejection rates at 1 and 6 months posttransplant were 2.3% and 2.3%. Kidney rejection rates at 1 and 6 months were 2.3% and 4.6%. Reasons for patient loss included one death from sepsis and one cardiovascular death. Reasons for kidney loss besides death included a thrombotic microangiopathy. Reasons for pancreas loss included three thromboses, one mild rejection/infection, and one duodenal segment leak with infection. All patients who have been free of rejection have been off steroids for the duration of follow-up. CONCLUSIONS: Newer immunosuppression protocols without maintenance steroids are possible with minimal rejection in the first 3 months and equivalent patient and graft survival rates compared with earlier protocols utilizing steroids. The potential beneficial long-term impact of steroid avoidance will require further study.

Cause of Death↗
PubMed2004

Intraoperative fluid management of living donor versus cadaveric liver transplant recipients.

Living donor liver transplantation has increasingly become an alternative to cadaveric donor liver transplants for select adult patients. Because these cases can be performed electively, living donor recipients may have better compensated liver disease at the time of surgery than cadaver donor recipients. However, it is unknown if this difference would have a significant effect on their intraoperative course. Therefore, we compared the intraoperative fluid management of patients receiving liver grafts from either living or cadaveric donors (n = 25, each group). Patient groups did not differ in demographics or baseline laboratory values. The duration of anesthesia and anhepatic phases were significantly longer in living donor cases (651 +/- 80 minutes vs 409 +/- 20 and 55 +/- 14 vs 45 +/- 6, P < .05). Adjusted for anesthesia time and patient weight, fluid administration (crystalloid and albumin) was not different between the two groups. Intraoperative transfusion requirements were also not significantly different in recipients from living donors versus cadaveric donors with regard to red blood cells, fresh frozen plasma, platelets, and cryoprecipitate. However, arterial oxygenation was better preserved in recipients from living donors. The PaO2/FiO2 (P/F) ratio at the end of the procedure was significantly better in patients receiving livers from living rather than from cadaveric donors (P/F ratio 335 +/- 114 mm Hg vs 271 +/- 174, P < .05). Our results indicate that while intraoperative fluid and transfusion requirements are similar, the impact of transplantation on pulmonary gas exchange is more pronounced in patients receiving organs from cadaveric donors. This difference may arise from longer cold ischemia times present in the cadaveric donor group.

Cadaver↗
PubMed2004

Resiquimod, a new immune response modifier from the family of imidazoquinolinamines, inhibits allergen-induced Th2 responses, airway inflammation and airway hyper-reactivity in mice.

BACKGROUND: Allergen-induced sensitization and airway disease are the results of adverse immune reactions against environmental antigens that may be prevented or inhibited by immune modifying strategies. OBJECTIVE: To investigate the effects of the novel immune response modifier resiquimod (R-848), from the family of imidazol-derivates, in a murine model of allergen-mediated Th2-immune responses and concomitant airway inflammation and airway hyper-reactivity. METHODS: BALB/c mice were systemically sensitized with ovalbumin (OVA) on days 1 and 14 and challenged with OVA aerosol on days 28 and 29. R-848 was applied intranasally to sensitized animals once prior to the first allergen airway challenge, on day 27. RESULTS: A single application of R-848 significantly reduced numbers of eosinophils and lymphocytes in bronchoalveolar lavage fluid and inhibited mucus gland hyperplasia, compared with sensitized and challenged controls. Associated with the decrease in airway inflammation, single intranasal treatment with R-848 abolished the development of airway hyper-reactivity after allergen sensitization and airway challenges. Additionally, Th2-cytokine production in lung tissues from sensitized and R-848-treated animals was reduced, whereas IL-12 and IFN-gamma production was increased, compared with non-treated sensitized mice. CONCLUSION: These data indicate that R-848 effectively inhibits allergen-induced airway inflammation and hyper-reactivity by modulation of increased Th2-immune responses.

Allergens↗
PubMed2003

Alterations in skeletal muscle structure are minimized with steroid withdrawal after renal transplantation.

BACKGROUND: Limitations in exercise capacity in kidney transplant recipients are thought to result in part from changes in muscle structure and function associated with immunosuppression therapy. METHODS: We compared the percent distribution of skeletal muscle fiber types, cross-sectional areas, and ultrastructural morphologies in kidney transplant recipients treated with standard prednisone maintenance therapy (n=21) to those undergoing rapid withdrawal of prednisone using Simulect (interleukin 2 receptor inhibitor) (n=13). Skeletal muscle biopsy specimens from the vastus lateralis were analyzed at 3 and 12 months after transplantation and compared with sedentary controls (n=15). RESULTS: Compared with the control group, the group receiving prednisone maintenance therapy had a significantly lower percentage of type I fibers and a higher percentage of type IIB/x fibers, evident at 3 and 12 months. Fiber type distribution in patients withdrawn from prednisone did not differ from controls. In patients withdrawn from prednisone, the cross-sectional areas of type I and IIA fibers were lower and the area of type IIB/x fibers was higher compared with controls. Likewise, ultrastructural studies revealed reduced volume densities of myofibrils and higher densities of interfibrillar and subsarcolemmal mitochondria. At 12 months there were no ultrastructural differences between the patients withdrawn from prednisone and controls. CONCLUSIONS: We conclude that prednisone maintenance therapy contributes to the lower exercise capacity by altering the ratio of type I to type IIB/x fibers and by reducing myofilament density. The increase in mitochondria in patients receiving prednisone may reflect a switch from carbohydrate to lipid metabolism resulting from the glucocorticoid therapy.

Adult↗
PubMed2003

De novo use of sirolimus in immunosuppression regimens in kidney and kidney-pancreas transplantation at the University of California, San Francisco.

At UCSF, we have used sirolimus in several immunosuppression regimens and protocols, and this article will summarize our experience in four areas. The purpose of the first study was to assess the efficacy of a sirolimus-based, calcineurin inhibitor-free regimen for the first 3 months after transplantation. Patients were treated with a calcineurin inhibitor-free regimen that consisted of daclizumab, sirolimus, mycophenolate mofetil (MMF), and conventional corticosteroids. Of nine patients, one (case #7) had an acute rejection episode (type IA) at 2 months after transplantation, which was fully reversed with corticosteroids. The second study was a prospective trial of calcineurin inhibitor-free regimen in patients with severe delayed graft function (DGF) (requiring dialysis). The immunosuppression regimen consisted of daclizumab, sirolimus, MMF, and corticosteroids. This immunosuppressive regimen was effective in patients with DGF; however, it was effective only in non-African American (non-AA) patients (AA had a significantly higher acute rejection rate at 1 year than non-AA, 63% vs 23%, P =.025). In some patients sirolimus was associated with a prolonged recovery from DGF. The addition of sirolimus to immunosuppressive agents provide the opportunity for safe steroid withdrawal (at day 5). We participated in a sirolimus-based, multicenter open-label trial of very early corticosteroid withdrawal. Primary renal transplant patients were enrolled in an immunosuppression regimen that consisted of basiliximab, sirolimus (target levels 8 to 15 ng/mL, 0 to 5 months, and 6 to 12 ng/mL, 6 to 12 months) and tacrolimus in a dose of 0.05 mg/kg BID (target levels 6 to 9 ng/mL). Two of 14 enrolled patients had an episode of acute rejection before steroids were withdrawn. No acute rejection episodes have occurred after steroids were withdrawn (6-month follow-up). The regimen of sirolimus and tacrolimus was well tolerated. Wound complications were not noted. Another important use of sirolimus has been its incorporation in the immunosuppressive regimens in kidney-pancreas transplantation. Our current protocol consists of thymoglobulin induction, combined with MMF, sirolimus, and low-dose tacrolimus, for maintenance therapy. Steroids are only utilized during the first 5 to 6 days following the transplant. This steroid-free maintenance regimen has been used in the last 30 enteric-drained, simultaneous pancreas-kidney transplants. Using this immunosuppressive approach, rejection rates are less than 10% for either the kidney or the pancreas.

Acute Disease↗
PubMed2003

Health-related fitness and quality of life following steroid withdrawal in renal transplant recipients.

BACKGROUND: Exercise capacity increases significantly soon after transplantation; however, over time it does not further improve and patients remain low compared to normal levels. The limitations to exercise following transplantation have not been identified, but may be related to immunosuppression therapy regimens that include prednisone. METHODS: We studied health-related fitness measures (cardiorespiratory fitness, muscle strength, and body composition) and quality of life in renal transplant recipients randomized into two groups: those using standard maintenance immunosuppression, including prednisone therapy (N = 14); and those undergoing rapid withdrawal of steroids using Simulect[interleukin-2 (IL-2) receptor inhibitor] (N = 9). Testing was done at 3 and 12 months following transplant and the 12-month data were compared to 15 normal sedentary controls. RESULTS: Compared to those maintained on steroids, the steroid withdrawal group showed greater gains in VO2peak (P = 0.05) and quadriceps peak torque (P = 0.05) and greater gains in the vitality score and the Physical Composite Scale on the SF-36 questionnaire (P < 0.05). At 1 year, all patients had significantly lower exercise capacity compared to the sedentary controls (P = 0.01). No differences were observed in body composition, with both patient groups increasing in body weight (primarily body fat) over time. At 12 months, all patients were not different in body fat percentage compared to the sedentary controls. CONCLUSION: We conclude that prednisone is not the cause for increased body fat following transplantation; however, it may contribute to lower spontaneous improvements in exercise capacity possibly by limiting increases in muscle strength. The low exercise capacity in all transplant recipients studied at 1 year suggests a need for exercise training to optimize physical functioning following transplant.

Adult↗
PubMed1997

Evidence for primary genetic determination of heart rate regulation: chromosomal mapping of a genetic locus in the rat.

BACKGROUND: We investigated whether an accelerated heart rate (HR), observed in the stroke-prone spontaneously hypertensive rat (SHRSP(HD)), is a primary, genetically determined trait and whether it contributes to blood pressure (BP) regulation in this model of polygenic hypertension. METHODS AND RESULTS: We measured BP and HR in SHRSP(HD) and normotensive Wistar-Kyoto rats (WKY), as well as in F2 hybrids bred from crossing the two strains, at baseline and after 12 days of dietary NaCl loading. Random marker genome screening and cosegregation analysis were performed on F2 hybrids derived from SHRSP(HD)/WKY-0(HD) (n=115) and SHRSP(HD)/WKY-1(HD) (n=139) crosses (WKY-0(HD) and WKY-1(HD) are two congenic WKY strains). HR in SHRSP(HD) was significantly higher than in WKY-0(HD) both at baseline (404+/-30 versus 375+/-46 bpm; P=.0034) and after NaCl (437+/-23 versus 364+/-40 bpm; P=10(-9)). BP in F2 hybrids showed no significant correlation with HR either at baseline or after NaCl loading. HR after NaCl loading but not at baseline was significantly linked in a recessive fashion to a locus on chromosome 3: in animals homozygous for the SHRSP(HD) allele, HR was 414+/-49 compared with 383+/-44 bpm in heterozygotes and WKY homozygotes (F(210,1)=19.7, P=1.4x10(-5), lod score=5.9). The putative BP-relevant gene at this locus, termed HR-SP1, showed no evidence of linkage to any of the BP parameters measured. CONCLUSIONS: Our results demonstrate that a genetic locus on rat chromosome 3, HR-SP1, contributes directly to the regulation of HR in SHRSP(HD) but exhibits no effect on BP. Thus, in addition to its modulation by reflex-mediated neurohumoral mechanisms, HR is also under the direct influence of primary genetic factors.

Analysis of Variance↗
PubMed1996

A multicenter analysis of the first experience with FK506 for induction and rescue therapy after pancreas transplantation.

Between May 1, 1993 and April 5, 1995, 154 pancreas allograft recipients at 9 institutions were given FK506 posttransplant. Three groups were studied: (1) recipients given FK506 initially for induction and maintenance therapy (n = 82), (2) recipients switched to FK506 for antirejection or rescue therapy (n = 61), and (3) recipients converted to FK506 for other reasons (n = 11). Of 82 patients in the induction group, 7 (9%) had simultaneous bone marrow (BM) and pancreas-kidney (SPK-BM) transplants, 54 (66%) had SPK transplants without BM, 14 (17%) had pancreas transplants alone (PTA), and 7 (9%) had pancreas after previous kidney transplants (PAK). All but 1 recipient was given quadruple immunosuppression (anti-T cell agents plus azathioprine and prednisone) for induction. The median FK506 starting dose was 4 mg/day p.o.; the median average FK506 blood level, 12 ng/ml. The most common side effects were neurotoxicity (16%), nephrotoxicity (13%), and gastrointestinal toxicity (9%). New-onset diabetes mellitus requiring permanent insulin therapy did not occur. Of 61 transplants in the rescue group, 44 (72%) were SPK, 11 (18%) PTA, and 6 (10%) PAK. All but 3 (95%) of the recipients had been on cyclosporine-azathioprine-prednisone triple immunosuppression before substitution of FK506 for cyclosporine; 46% of the recipients had one, and 54% > or = 2, rejection episodes preconversion. The most common side effects were nephrotoxicity (25%), neurotoxicity (23%), and gastrointestinal toxicity (21%). Two recipients were reconverted to cyclosporine because of transient hyperglycemia, and one recipient is on insulin. In the induction group, patient survival at 6 months was 90% for SPK, 100% for PTA, and 100% for PAK. According to a matched-pair analysis, pancreas graft survival for SPK recipients at 6 months was 87% for FK506 versus 70% for cyclosporine recipients (P = 0.04); for PTA recipients, 84% versus 66% (P = n.s.); and for PAK recipients, 80% versus 14% (P = 0.11). When technical failures and death with functioning grafts were censored, pancreas graft survival remained significantly better in the FK506 group. The incidence of first reversible rejection episodes by 6 months in FK506 recipients was 35% for SPK, 40% for PTA, and 20% for PAK. Of 75 pancreas grafts, 64 are currently functioning; in 5 recipients the pancreas failed (1 from rejection); 6 recipients died with a functioning pancreas graft. There were 3 posttransplant lymphomas (all EBV-positive); 2 recipients died and 1 is alive after subtotal colectomy and transplant pancreatectomy. In the antirejection rescue group, patient survival rates at 6 months were 91% for SPK, 100% for PTA, and 80% for PAK (P = n.s.). Pancreas graft survival rates at 6 months were 90% for SPK, 72% for PTA, and 40% for PAK. The incidence of first reversible rejection episodes after conversion to FK506 at 6 months was 44% in SPK, 54% in PTA, and 50% in PAK. Of 61 pancreas grafts, 51 are currently functioning; in 7 recipients the pancreas failed (5 from rejection); 3 recipients died with a functioning graft. There were no posttransplant lymphomas in the rescue group. This multicenter survey shows that FK506 in pancreas transplantation is associated with (1) a low rate of graft loss from rejection when used for induction therapy, (2) a high rate of graft salvage when used for rescue or rejection therapy, and (3) a very low rate of new-onset insulin-dependent diabetes mellitus. These encouraging results are tarnished by 3 posttransplant lymphomas in the induction group; a possible explanation is overimmunosuppression, but further (randomized) studies are necessary to analyze the long-term risk-benefit ratio of FK506 after pancreas transplantation.

Adolescent↗
PubMed1996

Decreased mortality from technical failure improves results in pediatric liver transplantation.

BACKGROUND: Until recently, pediatric liver transplantation was associated with a high rate of technical failure, which contributed substantially to the overall prognosis. OBJECTIVE: To assess the impact of technical failure on outcome in pediatric liver transplantation. DESIGN AND SETTING: We retrospectively analyzed 90 pediatric transplant procedures in a university medical center. PATIENTS: Between February 1988 and December 1995, 80 children ( < 15 years old) received 90 transplants. Fifty-three percent (n = 42) were less than 2 years of age, 45% (n = 36) had cholestatic liver disease, 26% (n = 21) had metabolic errors, and 11% (n = 9) had fulminant hepatitis. INTERVENTION: Patients underwent grafting using previously reported techniques, including cadaveric whole (61% [n = 55]), reduced-size (17% [n = 15]), and living related (22% [n = 20]) liver transplantation. MAIN OUTCOME MEASURES: Patient and graft survival and selected surgical complications. Outcomes were compared before (group 1) and after (group 2) the introduction of living related transplantation in July 1992. RESULTS: In group 1, 32 patients received 36 grafts (4 retransplants [13%]), and in group 2, 48 patients received 54 grafts (6 retransplants [13%]). Six- and 12-month patient survival rates were 78% (n = 25) and 75% (n = 24), respectively, for group 1 and 98% (n = 47) and 94% (n = 45) for group 2. Of the 9 deaths in group 1, 6 occurred early as a consequence of surgical complications, while in group 2, all 5 deaths that occurred were caused by the consequences of immunosuppression (lymphoproliferative disease, n = 2; late infections, n = 3). CONCLUSIONS: These results suggest that mortality caused by surgical complications has been reduced by improvement in management in recent years. Living related grafts have supplemented the graft supply and may be associated with the improved overall results. Despite these advances, children receiving transplants continue to experience the consequences of imperfect immunosuppression.

Adolescent↗
PubMed1996

The Y chromosome. Epistatic and ecogenetic interactions in genetic hypertension.

Previous studies have revealed conflicting evidence concerning a Y-chromosome effect on blood pressure (BP) in genetic crosses involving different strains of spontaneously hypertensive rats (SHR or SHRSP). We had previously found an approximately 16 mm Hg difference in systolic BP (P < 10(-7)) at baseline but not after dietary salt loading (P = .82) between F2 males derived from an SHRSPHD grandfather and a Wistar-Kyoto (WKYHD-0) grandmother and F2 males from a reciprocal cross (WKYHD-0 grandfather). When we examined F2 animals from reciprocal crosses between SHRSPHD and a congenic strain, WKYHD-1, which carries a 6-centimorgan-long SHRSPHD-homologous genomic fragment on chromosome 10 that contains a quantitative trait locus linked to BP (BP/SP-la), we found no significant differences either at baseline (P = .39) or after salt loading (P = .51) in the two reciprocal F2 cohorts. To test the hypothesis that Y-chromosome-autosomal epistasis accounts for the discrepant Y-chromosome effects on BP, we analyzed the interaction between BP/SP-1a and reciprocal cross status on BP in the two crosses. In the F2 (WKYHD-0xSHRSPHD) cross, no significant interaction was found for basal systolic BP (P = .89), arguing against a major influence of BP/SP-1a on the Y-chromosome effects on basal BP. However, a significant interaction between zygosity at the BP/SP-1a locus and reciprocal cross status for systolic BP after salt loading (P = .022) indicated that the BP/SP-1a-SHRSPHD allele exhibited a significant effect on BP after dietary excess salt only in males that inherited the SHRSP Y chromosome. These results support the relevance of a Y-chromosome effect on BP and suggest that a complex interplay of epistatic and ecogenetic interactions governs its effect on phenotype.

Animals↗
PubMed1995

Role of the cardiac renin-angiotensin system in human heart failure.

The local effects of angiotensin II (ANG II) on the heart may play an important role for the pathophysiology of cardiovascular disease. Numerous in vitro studies have demonstrated that angiotensin II has distinctive cellular effects in the cardiovascular system which are independent from its effects on blood pressure. These have led to the hypothesis that activation of the angiotensin system in the heart could be of functional relevance for the adaptive processes in several cardiovascular disorders such as cardiac hypertrophy heart failure. This concept has been further supported by clinical studies showing the beneficial effects of angiotensin-converting enzyme inhibitors in these circumstances. In order to study the gene regulation of renin-angiotensin system components in cardiac disorders we investigated the gene expression of angiotensin converting enzyme in human heart failure. Results showed that the enzyme is activated locally in this condition, supporting previous studies in animals. Taken together with recent evidence from genetic studies linking the enzyme to myocardial infarction and cardiac hypertrophy, our findings are in support of the notion that angiotensin converting enzyme plays a central role in cardiovascular physiology and pathophysiology.

Angiotensin II↗