Homogenization of regional river dynamics by dams and global biodiversity implications

Global biodiversity in river and riparian ecosystems is generated and maintained by geographic variation in stream processes and fluvial disturbance regimes, which largely reflect regional differences in climate and geology. Extensive construction of dams by humans has greatly dampened the seasonal and interannual streamflow variability of rivers, thereby altering natural dynamics in ecologically important flows on continental to global scales. The cumulative effects of modification to regional-scale environmental templates caused by dams is largely unexplored but of critical conservation importance. Here, we use 186 long-term streamflow records on intermediate-sized rivers across the continental United States to show that dams have homogenized the flow regimes on third- through seventh-order rivers in 16 historically distinctive hydrologic regions over the course of the 20th century. This regional homogenization occurs chiefly through modification of the magnitude and timing of ecologically critical high and low flows. For 317 undammed reference rivers, no evidence for homogenization was found, despite documented changes in regional precipitation over this period. With an estimated average density of one dam every 48 km of third- through seventh-order river channel in the United States, dams arguably have a continental scale effect of homogenizing regionally distinct environmental templates, thereby creating conditions that favor the spread of cosmopolitan, nonindigenous species at the expense of locally adapted native biota. Quantitative analyses such as ours provide the basis for conservation and management actions aimed at restoring and maintaining native biodiversity and ecosystem function and resilience for regionally distinct ecosystems at continental to global scales.     

Hyperpolarized 13C allows a direct measure of flux through a single enzyme-catalyzed step by NMR

(13)C NMR is a powerful tool for monitoring metabolic fluxes in vivo. The recent availability of automated dynamic nuclear polarization equipment for hyperpolarizing (13)C nuclei now offers the potential to measure metabolic fluxes through select enzyme-catalyzed steps with substantially improved sensitivity. Here, we investigated the metabolism of hyperpolarized [1-(13)C(1)]pyruvate in a widely used model for physiology and pharmacology, the perfused rat heart. Dissolved (13)CO(2), the immediate product of the first step of the reaction catalyzed by pyruvate dehydrogenase, was observed with a temporal resolution of approximately 1 s along with H(13)CO(3)(-), the hydrated form of (13)CO(2) generated catalytically by carbonic anhydrase. In hearts presented with the medium-chain fatty acid octanoate in addition to hyperpolarized [1-(13)C(1)]pyruvate, production of (13)CO(2) and H(13)CO(3)(-) was suppressed by approximately 90%, whereas the signal from [1-(13)C(1)]lactate was enhanced. In separate experiments, it was shown that O(2) consumption and tricarboxylic acid (TCA) cycle flux were unchanged in the presence of added octanoate. Thus, the rate of appearance of (13)CO(2) and H(13)CO(3)(-) from [1-(13)C(1)]pyruvate does not reflect production of CO(2) in the TCA cycle but rather reflects flux through pyruvate dehydrogenase exclusively.     

Amplification of low-frequency antiviral CD8 T cell responses using autologous dendritic cells.

OBJECTIVE: To utilize the potent antigen-presenting capacity of mature dendritic cells (MDC) in order to develop a rapid, sensitive method for quantifying antigen-specific CD8 T cells present at low frequency in peripheral blood. DESIGN: Peripheral blood mononuclear cells (PBMC) were obtained from seven HIV-1-positive individuals with low to moderate CD8 T cell responses, including five on highly active antiretroviral therapy (HAART). IFN-gamma ELISPOT assays were performed using either monocytes or MDC to present antigens expressed by recombinant vaccinia viruses (r-VV). METHODS: Peripheral blood-derived monocytes were cultured for 5-6 days in the presence of IL-4 and granulocyte macrophage colony-stimulating factor, then matured in monocyte-conditioned medium. MDC were infected with r-VV and co-cultured in an ELISPOT assay with autologous monocyte-depleted PBMC. RESULTS: Relative to autologous monocytes, MDC amplified detection of antigen-specific CD8 T cells by 2-30-fold in response to antigens from HIV-1, Epstein-Barr virus and cytomegalovirus. Furthermore, antigenic specificities were revealed that had not been detected using standard ELISPOT of PBMC. CONCLUSION: This assay will prove useful for the detection of memory T cells present at low frequency, and may be of interest for identifying subdominant cytotoxic T lymphocyte epitopes. This method may have broad applications for the detection of antiviral CD8 T cell responses in patient populations in whom such responses have been difficult to detect, including HIV-1-seropositive individuals with advanced disease or undergoing HAART.     

Effects of variable concentrations of inhaled nitric oxide and oxygen on the lungs of newborn piglets

We previously demonstrated that inhalation of high concentrations of nitric oxide (iNO) and oxygen for 48 hr causes significant lung injury in newborn piglets. To determine if these effects persist at lower concentrations, groups of newborn piglets were mechanically ventilated for 48 hr with (study 1) constant O(2) (90-100%) and decreasing iNO (100-2 ppm) or (study 2) constant iNO (50 ppm) and decreasing O(2) (95-30%). Bronchoalveolar lavage (BAL) fluid was assayed for surfactant function, and markers of lung inflammation and physiologic parameters were monitored.Neutrophil chemotactic activity (NCA), % neutrophils, and total protein (TP) concentrations decreased significantly in BAL fluid of study 1 piglets as iNO was reduced and inhaled oxygen fraction remained constant, indicating less pulmonary injury at low iNO levels. Low-dose iNO (2 ppm) did not have antiinflammatory effects. However, surfactant function was minimally affected by lowering iNO, and was abnormal in all groups. In contrast, in study 2, pulmonary inflammation and injury were lower when O(2) was decreased to 70% or less, with iNO constant at 50 ppm. Surfactant function normalized and oxygenation improved in study 2 piglets when the inhaled oxygen fraction was decreased and iNO remained constant.These data suggest that iNO- and O(2)-induced lung injury may be minimized by weaning O(2) or iNO, although better physiologic function may be obtained when iNO concentrations are constant and O(2) is reduced. This has important implications in the clinical management of critically ill newborns treated with O(2) and iNO for pulmonary disorders.     

Dose accuracy and injection force of disposable pens delivering pramlintide for the treatment of diabetes

Background

The pen injection format, typically used for insulin administration, has been adapted for the injectable, noninsulin diabetes therapy pramlintide. Administered before major meals, pramlintide therapy requires two to four injections/day in addition to the patients’ usual insulin injections. The dose accuracy and injection force was determined for the 60 and 120 µg pramlintide pens.

Methods

Dose accuracy testing was conducted at two sites on multiple 60 µg (15, 30, and 60 µg doses) and 120 µg pens (60 and 120 µg doses) at prespecified temperatures (5–40 °C) and humidities (0–75%) using 29 G half-inch needles. All pens were stabilized under testing conditions for 4 h prior to testing. One site used a compression load cell (Zwick device) to test pens; one site performed tests manually.Injection-force testing was conducted at one site on multiple 60 and 120 µg pens at multiple temperatures (18–28 °C) and humidities (25–75%) using 29 and 31 G half-inch needles and an injection speed of 150 m/min. Injection-force testing was performed using a Zwick device.

Results

Dose accuracy for all pens tested, regardless of location, reproducibly met/exceeded acceptance criteria. Mean percentage of dose accuracy was 96.04 to 102.45% [standard deviations (SDs) 0.3 to 1.4 µg] for the 60 µg pen and 98.16 to 101.83% (SDs 0.4 to 2.5 µg) for the 120 µg pen. The average injection force across both pens did not exceed 7 N regardless of needle size.

Conclusions

High dose accuracy and low injection force were observed for the 60 and 120 µg pens under a variety of conditions.     

The significance of HLA-DRB1 matching on clinical outcome after HLA-A, B, DR identical unrelated donor marrow transplantation

Despite matching for serologically defined HLA-A, B, DR antigens, acute graft-versus-host disease (GVHD) is a major complication contributing to increased morbidity and mortality in patients who undergo marrow transplantation from unrelated donors. The extent to which unrecognized mismatching for alleles that encode DR1-DR18 contribute to the increased risk of acute GVHD and overall survival is unknown. We analyzed 364 patients and their HLA-A, B, DR serologically matched donors to determine whether molecular typing of DRB1 alleles can allow more accurate donor/recipient matching and thereby improve clinical outcome after marrow transplantation. DRB1 alleles were typed by sequence-specific oligonucleotide probe hybridization methods. Selected alleles were confirmed by DNA sequencing. Of the 364 pairs, 305 were matched and 59 were mismatched for DRB1. The probability of moderate to severe acute GVHD was .48 for the matched and .70 for the mismatched patients. Compared with mismatched patients, the estimated relative risk (RR) of GVHD for matched patients was .58 (95% confidence interval [CI], .40 to .85). DRB1 matching decreased the risk of transplant- related mortality (RR, .66; 95% CI, .44 to .97) and was associated with decreased overall mortality (RR, .71; 95% CI, .51 to 1.0). Therefore, matching DRB1 alleles of the donor and recipient decreases the risk of acute GVHD and improves survival after unrelated marrow transplantation. These results indicate that prospective matching of patients and donors for DRB1 alleles is warranted.     

Unrelated donor marrow transplantation in children

Eighty-eight children 0.5 to 17 years of age (median, 9 years of age) received an unrelated donor marrow transplant for treatment of chronic myeloid leukemia (CML; n = 16), acute lymphoblastic leukemia (ALL) in first or second remission (n = 15) or more advanced stage (n = 28), acute myeloid leukemia (AML; n = 13), or other hematologic diseases (n = 16) between June 1985 and April 1993. All patients were conditioned with cyclophosphamide and total body irradiation and received a combination of methotrexate and cyclosporine as graft-versus-host disease (GVHD) prophylaxis. Fourty-six patients received transplants from HLA-identical donors and 42 patients received transplants from donors who were minor-mismatched at one HLA-A or B or D/DRB1 locus. The Kaplan-Meier estimates of disease-free survival and relapse were 75% and 0% for patients with CML, 47% and 20% for ALL in first or second remission, 10% and 60% for ALL in relapse or third remission, 46% and 46% for AML in first remission (n = 1) or more advanced disease (n = 12), and 29% and 69% for other diseases. HLA disparity was not significantly associated with lower disease-free survival, but the results suggest more relapses in HLA-matched recipients and there was significantly more transplant-related mortality in mismatched recipients (51% v 24%, P = .04). Most deaths were due to infections associated with acuteor chronic GVHD and occurred within the first 2 years after transplantation. Granulocyte engraftment occurred in all evaluable patients. Sixty-three percent of HLA-matched and 57% of HLA- mismatched recipients were discharged home disease-free at a median of 98 and 103 days, respectively, after transplantation (P = not significant [NS]). The incidence of grades II-IV acute GVHD was 83% in HLA-matched and 98% in HLA-mismatched recipients (P = .009). The incidence of chronic GVHD was 60% in HLA-matched and 69% in HLA- mismatched recipients (P = NS). One or multiple late adverse events such as cataracts, osteonecrosis of the hip or knee, restrictive or obstructive pulmonary disease, and hypothyroidism have occurred in 11 of 33 (33%) surviving patients. Immunosuppression was discontinued in 58% of surviving patients, including all 12 patients surviving more than 3.2 years, all of whom have a Lansky or Karnofsky score of 100%.(ABSTRACT TRUNCATED AT 400 WORDS)     

Rearrangement of the T cell receptor gamma-chain gene in childhood acute lymphoblastic leukemia

We analyzed rearrangements of the T cell receptor gamma-chain (T gamma) gene as well as rearrangements of the T cell receptor beta-chain (T beta) gene and immunoglobulin heavy-chain (IgH) gene in 68 children with acute lymphoblastic leukemia (ALL). All 15 patients with T cell ALL showed rearrangements of both T beta and T gamma genes. Twenty-four of 53 non-T, non-B ALL patients (45%) showed T gamma gene rearrangements and only 14 of these also showed T beta gene rearrangements. Only a single patient rearranged the T beta gene in the absence of T gamma gene rearrangement. The rearrangement patterns of the T gamma gene in non-T, non-B ALL were quite different from those observed in T cell ALL, as 20 of 23 patients retained at least one germline band of the T gamma gene. In contrast, all T cell ALL patients showed no retention of germline bands. These data indicate that rearrangement of the T gamma gene is not specific for T cell ALL. Further, the results also suggest that T gamma gene rearrangement precedes T beta gene rearrangement. The combined analysis of rearrangement patterns of IgH, T beta, and T gamma genes provides new criteria for defining the cellular origin of leukemic cells and for further delineation of leukemia cell heterogeneity.     

Clinical features and outcome of patients with cutaneous melioidosis during a nosocomial outbreak in a temperate region of Australia

Six cases of cutaneous melioidosis from southwestern Australia, a non‐endemic region occurred as a result of Burkholderia pseudomallei contamination of normal saline that was used for irrigating superficial wounds. Treatment with parenteral meropenem, given by continuous infusion for 2 weeks, followed by oral antibiotics was successful in all cases.     

p53 gene mutations and protein accumulation in human ovarian cancer.

Mutations of the p53 gene on chromosome 17p are a common genetic change in the malignant progression of many cancers. We have analyzed 38 malignant tumors of ovarian or peritoneal müllerian type for evidence of p53 variations at either the DNA or protein levels. Genetic studies were based on single-strand conformation polymorphism analysis and DNA sequencing of exons 2 through 11 of the p53 gene; mutations were detected in 79% of the tumors. These data show a statistically significant association between mutations at C.G pairs and a history of estrogen therapy. Two of 20 patients whose normal tissue could be studied carried germ-line mutations of p53. Immunohistochemical analysis of the p53 protein was carried out using monoclonal antibody PAb1801. Ninety-six percent of the missense mutations were associated with abnormal accumulation of p53 protein, but nonsense mutations, a splicing mutation, and most deletions did not result in p53 protein accumulation. A statistically significant association between p53 protein accumulation in poorly differentiated stage III serous carcinomas and small primary tumor size at diagnosis was found, perhaps suggesting that p53 protein accumulation accelerates the metastatic spread from a primary tumor. Overall, our findings indicate that alterations of p53 play a major role in ovarian cancer, including predisposition to the disease in some patients, and suggest a possible mechanism for somatic mutations leading to this cancer.