Glutamine and hyperammonemic crises in patients with urea cycle disorders.

UNLABELLED: Blood ammonia and glutamine levels are used as biomarkers of control in patients with urea cycle disorders (UCDs). This study was undertaken to evaluate glutamine variability and utility as a predictor of hyperammonemic crises (HACs) in UCD patients. METHODS: The relationships between glutamine and ammonia levels and the incidence and timing of HACs were evaluated in over 100 adult and pediatric UCD patients who participated in clinical trials of glycerol phenylbutyrate. RESULTS: The median (range) intra-subject 24-hour coefficient of variation for glutamine was 15% (8-29%) as compared with 56% (28%-154%) for ammonia, and the correlation coefficient between glutamine and concurrent ammonia levels varied from 0.17 to 0.29. Patients with baseline (fasting) glutamine values >900 µmol/L had higher baseline ammonia levels (mean [SD]: 39.6 [26.2]µmol/L) than patients with baseline glutamine ≤ 900 µmol/L (26.6 [18.0]µmol/L). Glutamine values >900 µmol/L during the study were associated with an approximately 2-fold higher HAC risk (odds ratio [OR]=1.98; p=0.173). However, glutamine lost predictive significance (OR=1.47; p=0.439) when concomitant ammonia was taken into account, whereas the predictive value of baseline ammonia ≥ 1.0 upper limit of normal (ULN) was highly statistically significant (OR=4.96; p=0.013). There was no significant effect of glutamine >900 µmol/L on time to first HAC crisis (hazard ratio [HR]=1.14; p=0.813), but there was a significant effect of baseline ammonia ≥ 1.0 ULN (HR=4.62; p=0.0011). CONCLUSIONS: The findings in this UCD population suggest that glutamine is a weaker predictor of HACs than ammonia and that the utility of the predictive value of glutamine will need to take into account concurrent ammonia levels.

Use of IL3 and chromatin-modifying reagents valproic acid and 5-aza-2'-deoxycytidine to affect mobilized peripheral blood CD34+ cell fate decisions.

BACKGROUND AND OBJECTIVES: Culture of blood CD34(+) cells with chromatin-modifying agents can lead to an increase in marrow repopulating cells and in the case of valproic acid increased erythroid cell colony formation. We undertook research to help understand what effects these reagents have on mobilized peripheral blood (MPB) CD34(+) cells. MATERIALS AND METHODS: Mobilized peripheral blood was obtained under informed consent and ethics committee approval from nine patients and allograft donors. Epigenetic modifiers valproic acid and 5-aza-2'-deoxycytidine were used singly or in combination with each other and with IL3 when culturing mobilized peripheral blood CD34(+) cells. Cultured cells were subsequently used in flow cytometry and colony-forming unit assay experiments. RESULTS: Addition of IL3 to the in vitro cell growth medium improved the expansion and maintained the functionality of CD34(+) cells. Valproic acid and IL3 also work synergistically to increase the numbers of CD34(+) /CD36(+) double-positive cells. We found that an apparent increase in red cell colony formation was a result of a decrease in white cell colonies, with no overall increase in red cell colonies when equivalent numbers of CD34(+) cells are plated. CONCLUSIONS: Mobilized peripheral blood CD34(+) stem and progenitor cells are affected by chromatin-modifying agents and IL3 giving higher numbers of CD34(+) /CD36(+) double-positive erythroid progenitors.

Analysis of Wnt pathway genes during ex vivo expansion and neutrophil differentiation of umbilical-cord-blood-derived CD34 cells.

Previous work has shown that optimal ex vivo expansion and differentiation of CD34(+) progenitor cells into neutrophils is by addition of Flt3-L, SCF and G-CSF. Here we report that a variety of genes involved in the WNT pathway are transcriptionally active in both undifferentiated and differentiated umbilical cord blood CD34(+) cells, however statistically significant changes in gene expression are not always consistent across UCB samples.

Blood donor derived dendritic cells and cytotoxic T cells for specific fusion-gene adoptive immunotherapy.

BACKGROUND AND OBJECTIVES: Therapeutic immunological reagents tailored to individual patients have been shown to be a viable treatment strategy for some forms of leukaemia. This work investigates the possibility of using blood donations as a source of leukaemia-specific immune therapeutics. MATERIALS AND METHODS: The acute promyelocytic cell line NB4 carrying the PML-RAR alpha fusion was used as a target for cytotoxic T lymphocytes (CTL) stimulated to recognize the fusion. Stimulation of CTL was by production of dendritic cells pulsed with plasmid vectors containing polymerase chain reaction (PCR)-generated sequences of PML-RAR alpha derived from NB4 cells. PCR primer design included a Kozak consensus sequence to allow correct translation of the nucleic acid into protein. Identification of specific cytotoxicity was by both Granzyme B ELISPOT and by (51)Cr-release assays. RESULTS: Specific CTL activity targeting NB4 cells can be generated from donor-derived peripheral blood mononuclear cells. However, individual donors appear to respond differently to the length of stimulatory sequence encoded in the vector. Use of an internal methionine in the PML gene, which also satisfies the Kozak rules, allows translation in vitro and, thus, might provide a suitable start site for stimulation using acute promyelocytic leukaemia-specific sequence. CONCLUSION: The work presented here suggests that blood donor derived dendritic cells can be used to stimulate leukaemia-specific CTL from the same donation ex vivo. This would enable the generation of patient-specific therapeutics from major histocompatibility (MHC)-matched allogeneic donors. However, different MHC-matched donors might vary in their response depending on the length of the antigenic sequence.

A comparison of ON-PUMP vs OFF-PUMP coronary artery bypass surgery among low, intermediate, and high-risk patients: the Hartford Hospital experience.

BACKGROUND: Off-pump coronary artery bypass (OP-CAB) graft surgery is being used with increasing frequency. This study was designed to compare OP-CAB outcomes with conventional surgical revascularization using cardiopulmonary bypass (CPB) in patients with varying risk categories at a high-volume center. METHODS AND RESULTS: Between 1/1/1999 and 1/31/2001, bypass surgery was performed on 1,312 patients, including 348 OP-CAB cases and 964 CPB cases. Compared to CPB cases, OP-CAB patients were more likely to be female and had a lower incidence of three vessel coronary artery disease, prior percutaneous intervention, and prior bypass surgery. Postoperatively, OP-CAB patients had a lower incidence of renal failure and prolonged ventilatory support, as well as a lower composite endpoint of inhospital mortality, perioperative myocardial infarction, cerebrovascular accident, and/or renal failure. In addition, OP-CAB patients required fewer transfusions and had a shorter total length of hospital stay. In general, morbidity and mortality increased in both OP-CAB and CPB groups with increasing Parsonnet score. CONCLUSIONS: OP-CAB surgery is a safe and effective alternative to conventional coronary artery bypass graft (CABG) surgery, with a lower incidence of major in-hospital adverse clinical events and a decreased requirement for medical resources. Adverse OP-CAB outcomes correlate well with pre-operative Parsonnet Score.

A complicated case of acute bacterial endocarditis.

Acute bacterial endocarditis continues to be a significant medical and surgical problem in the United States. The authors describe a complicated case of acute Staphylococcus aureus endocarditis in an 18-year-old man. The patient suffered multiple systemic emboli requiring aggressive medical and surgical intervention.

A promoter region mutation affecting replication of the Tetrahymena ribosomal DNA minichromosome.

In the ciliated protozoan Tetrahymena thermophila the ribosomal DNA (rDNA) minichromosome replicates partially under cell cycle control and is also subject to a copy number control mechanism. The relationship between rDNA replication and rRNA gene transcription was investigated by the analysis of replication, transcription, and DNA-protein interactions in a mutant rDNA, the rmm3 rDNA. The rmm3 (for rDNA maturation or maintenance mutant 3) rDNA contains a single-base deletion in the rRNA promoter region, in a phylogenetically conserved sequence element that is repeated in the replication origin region of the rDNA minichromosome. The multicopy rmm3 rDNA minichromosome has a maintenance defect in the presence of a competing rDNA allele in heterozygous cells. No difference in the level of rRNA transcription was found between wild-type and rmm3 strains. However, rmm3 rDNA replicating intermediates exhibited an enhanced pause in the region of the replication origin, roughly 750 bp upstream from the rmm3 mutation. In footprinting of isolated nuclei, the rmm3 rDNA lacked the wild-type dimethyl sulfate (DMS) footprint in the promoter region adjacent to the base change. In addition, a DMS footprint in the origin region was lost in the rmm3 rDNA minichromosome. This is the first reported correlation in this system between an rDNA minichromosome maintenance defect and an altered footprint in the origin region. Our results suggest that a promoter region mutation can affect replication without detectably affecting transcription. We propose a model in which interactions between promoter and origin region complexes facilitate replication and maintenance of the Tetrahymena rDNA minichromosome.

A better long-term outcome in cardiac transplant recipient with a history of previous open heart operations.

OBJECTIVE: To investigate the effect of previous open heart operations (POHO) on the outcome of heart transplantation (HTX). METHODS: Between November 1984 and May 1996, HTX was performed on 151 patients at Hartford Hospital. Among them, 61 patients had previous open heart operations (POHO) (group A), and 90 did not (group B). The average follow-up period was 1615 +/- 1185 days for group A and 1330 +/- 1125 days for group B. The recipient age was 55 +/- 10 years for group A and 48 +/- 12 years for group B (P < 0.01). There were 17 patients (26%) in group A and 14 (50%) in group B who were over 60 years of age. There was more coronary artery disease (74% versus 37%, P < 0.001) as etiology, and more diabetics in group A (P < 0.02). RESULTS: The time for cardiopulmonary bypass (133 +/- 20 min versus 106 +/- 18 min, P < 0.01) and aortic clamp time (73 +/- 16 min versus 61 +/- 13 min, P < 0.01) were longer in group A. The operative mortality (within 30 days) was 0 and 2.2%, and the cumulative deaths were 16 (26%) and 43 (48%) respectively for group A and group B (P < 0.01). The causes of death were (group A vs group B): infection (31% vs 26%), rejection (13% vs 28%, P < 0.05), malignancy (25% vs 16%), cardiac event (6% vs 14%) and others (25% vs 16%). In patients over 60, there were 4 deaths (24%) in group A and 7 (50%) in group B. The difference was not significant. No patients died of rejection in this subgroup. The actuarial survival rates in group A versus group B were: 1 year, 93% versus 83%; 2 years, 85% versus 74%; 3 years, 81% versus 71%; 5 years, 76% versus 58%; and 10 years, 57% versus 24% (P < 0.01). CONCLUSION: The survival rate in patients who had POHO is much higher than that in patients who had HTX as their primary operation.

Retrograde flush and cold storage for twenty-two to twenty-five hours lung preservation with and without prostaglandin E1.

BACKGROUND: Our previous study showed that retrograde flush through the left atrium is better than antegrade flush in 6-hour lung preservation. Whether it is feasible in long-term lung preservation is not clear. Several studies suggested that prostaglandin E1 may not be necessary in retrograde flush because of the low vascular resistance on the venous side. This study evaluates the effects of retrograde flush and prostaglandin E1 in 24-hour lung preservation. METHODS: Canine donor lungs were retrograde flushed with University of Wisconsin solution. Group A (n = 7) was pretreated with prostaglandin E1. No prostaglandin E1 was used in group B (n = 7). After flush and cold storage at 4 degrees C for 22 to 25 hours, left lung allotransplantation was performed. Measurements were taken before transplantation (baseline), and at 10, 30, 60, and 120 minutes after transplantation while the right pulmonary artery was occluded. RESULTS: After 120 minutes of reperfusion, the oxygen tension and carbon dioxide tension were 643 +/- 24 and 37 +/- 3 mm Hg in group A and 600 +/- 29 and 37 +/- 3 mm Hg in group B, respectively (p = NS). Pulmonary artery pressure (group A vs group B) was 20 +/- 1 versus 28 +/- 2 mm Hg (p < 0.01); right atrium pressure: 4 +/- 1 versus 8 +/- 1 mm Hg (p < 0.01); left pulmonary vascular resistance: 1109 +/- 51 versus 1525 +/- 133 dyne.sec.cm-5 (p < 0.05); airway resistance: 22 +/- 1 versus 24 +/- 1 cm H2O/L/sec (p = NS); lung dynamic compliance: 30 +/- 1 versus 26 +/- 1 cc/cm (p < 0.05) respectively. As compared with the baseline (19 +/- 1), airway resistance was significantly increased after 2 hours of reperfusion in group B (p < 0.05). Electron microscopy revealed that type I pneumocytes, capillary endothelial cells, and epithelial cells of bronchi were well preserved and the contents of lamellar bodies of type II pneumocyte were reduced. CONCLUSIONS: Canine lung was well preserved by retrograde flush and cold storage with University of Wisconsin solution after 24 hours preservation. Pretreatment of prostaglandin E1 is helpful in reducing pulmonary vascular resistance and airway resistance and improving lung dynamic compliance.

Coronary stent placement as a bridge to coronary artery bypass surgery in an unstable, anemic Jehovah's Witness patient: a case report and review of bloodless surgery techniques.

Bloodless cardiac surgery would be optimal for all patients undergoing major or complex heart surgery; however, for Jehovah's Witnesses it involves a religious law and is fundamentally mandated. In this context, we review a case of unstable angina with associated anemia requiring catheterization and definitive intervention in a Jehovah's Witness patient. Coronary stenting to stabilize the acute coronary syndrome is described with definitive total revascularization performed by coronary artery bypass graft surgery after utilizing erythropoietin and aggressive blood conservation techniques.

Retrograde versus antegrade flush in canine left lung preservation for six hours.

BACKGROUND: Retrograde flush through the left atrium is now used by some investigators in clinical lung preservation. However, to date there are no studies which compare its result with that of routine antegrade flush. METHODS: Mongrel dogs were divided into two groups: antegrade group (n = 7) and retrograde group (n = 8). After flush and 6 hours of cold storage in Euro-Collins solution, the left lung was transplanted in weight matched recipients, and their right pulmonary artery was then clamped at 10-, 30-, 60-, and 120-minute intervals for 10 minutes to test the lung function. The ultrastructure of lungs in both groups were also studied. RESULTS: Results showed the following (antegrade group versus retrograde group): the wet/dry ratio of the transplanted lung was 7.14 +/- 0.15 versus 6.33 +/- 0.20 (p < 0.01); the arterial oxygen tension (mm Hg) was 389 +/- 42 versus 534 +/- 23 (p < 0.05) and 370 +/- 51 versus 580 +/- 37 (p < 0.01) at 60 and 120 minutes, respectively. The peak airway pressure (cm H2O) was 23.4 +/- 0.8 versus 20.6 +/- 0.6 (p < 0.05) and 23.7 +/- 0.6 versus 21.3 +/- 0.8 (p < 0.05) at 10 and 60 minutes, respectively. Electron microscopic studies showed that at the end of preservation, type I and type II pneumocytes and capillaries were normal in both groups. Occluded capillaries with red blood cells were found in the antegrade group. After reperfusion, damaged epithelium and thicker air-blood barrier were found in the antegrade group. CONCLUSIONS: Retrograde flush offers a better lung preservation with less edema, decreased airway resistance, and improved oxygenation as compared with the antegrade group in 6 hours lung preservation.

Replication of an rRNA gene origin plasmid in the Tetrahymena thermophila macronucleus is prevented by transcription through the origin from an RNA polymerase I promoter.

In the somatic macronucleus of the ciliate Tetrahymena thermophila, the palindromic rRNA gene (rDNA) minichromosome is replicated from an origin near the center of the molecule in the 5' nontranscribed spacer. The replication of this rDNA minichromosome is under both cell cycle and copy number control. We addressed the effect on origin function of transcription through this origin region. A construct containing a pair of 1.9-kb tandem direct repeats of the rDNA origin region, containing the origin plus a mutated (+G), but not a wild type, rRNA promoter, is initially maintained in macronuclei as an episome. Late, linear and circular replicons with long arrays of tandem repeats accumulate (W.-J. Pan and E. H. Blackburn, Nucleic Acids Res, in press). We present direct evidence that the +G mutation inactivates this rRNA promoter. It lacks the footprint seen on the wild-type promoter and produces no detectable in vivo transcript. Independent evidence that the failure to maintain wild-type 1.9-kb repeats was caused by transcription through the origin came from placing a short DNA segment containing the rRNA gene transcriptional termination region immediately downstream of the wild-type rRNA promoter. Insertion of this terminator sequence in the correct, but not the inverted, orientation restored plasmid maintenance. Hence, origin function was restored by inactivating the rRNA promoter through the +G mutation or causing termination before transcripts from a wild-type promoter reached the origin region. We propose that transcription by RNA polymerase I through the rDNA origin inhibits replication by preventing replication factors from assembling at the origin.

Cloning and sequence of the feline max, and max 9 transcripts.

Max is the recently discovered heterodimeric partner of the human myc oncogene product. In this report we describe the cloning and sequencing of two differentially spliced transcripts of the feline max gene. Previously published data have shown both myc and max to be highly conserved amongst species, and indeed there is a 100% homology between feline max and max, while the murine equivalent myn is 98% homologous at the amino acid level, with the nucleotide sequences showing a similarity of 98% and 95% respectively.

Univentricular support results in reduction of pulmonary resistance and improved right ventricular function.

A retrospective analysis was performed to assess the effects of univentricular support on the transpulmonary gradient (TPG), pulmonary vascular resistance (PVR), total pulmonary resistance (TPR), and right ventricular ejection fraction (RVEF) in 16 patients who spent from 2 to 144 days (mean, 61) on the Novacor left ventricular assist system ([LVAS] Novacor Corp., Baxter Healthcare, Oakland, CA) as a bridge to cardiac transplantation. Results revealed a significant reduction in the TPR, and improvement in RVEF while patients were on the LVAS. After orthotopic heart transplantation (OHTx), TPG and PVR were significantly lower than when calculated before support. It was concluded, therefore, that the reduction in the TPR and the improvement in the RVEF, seen in patients who were provided univentricular support with the Novacor LVAS, are associated with a significant reduction in the TPG and the PVR, which are persistent after OHTx. Four patients who otherwise would have been considered at higher risk for OHTx because of elevated pulmonary resistance before veniventricular support underwent successful OHTx after LVAS support.

Influence of sterile protective sleeves on the sterility of pulmonary artery catheters.

Eighty-seven pulmonary artery catheters (PACs) with sterile protective sleeves were placed into 69 surgical ICU patients by one of the following two methods: through an introducer placed in a new, percutaneous site or by exchanging an indwelling catheter for an introducer. On removal, 5-cm catheter segments from the catheter tip and from within the introducer and sleeve, peripheral blood, and blood drawn from the PAC distal port were cultured quantitatively. Sleeve segment cultures were sterile if catheterization was less than 48 h and had been accomplished through a new percutaneous site. The risk of growing greater than 10(3) colonies on the tip and introducer segment increased to greater than 30% when PACs were left in over 96 h. The incidence of catheter-related bacteremia (CRB), defined as the simultaneous growth of identical organisms from the blood and the PAC tip, was 5.3% but may have been underestimated. CRB was associated with the use of corticosteroids (p = .009) and with cultures from any PAC segment growing more than 10(3) colonies (p less than .01). Although our data suggest that the use of the sterile protective sleeve is associated with a low risk of colonization, further study will be required to delineate the relationship between the use of protective sleeves and CRB.

A manifold to measure exhaled tidal volume during high-frequency jet ventilation.

A simple manifold is described that enables accurate measurement of tidal volume and exhaled minute volume during high-frequency jet ventilation. The system was tested at zero end-expiratory pressure and during continuous positive airway pressure of up to 15 cm H2O, at jet drive pressures of up to 40 psig.