Breath ammonia depletion and its relevance to acidic aerosol exposure studies.

It is thought that gaseous ammonia in breath neutralizes acidic air pollution and thereby potentially mitigates the pulmonary effects of pollution. The efficacy of breath ammonia depletion methods reported in recent acid aerosol exposure-health response studies was investigated. Fourteen subjects (21 to 54 y of age) performed one or more of the following hygiene maneuvers: (a) acidic oral rinse (pH 2.5); (b) tooth brushing, followed by acidic oral rinse; (c) tooth brushing, followed by distilled water rinse; and (d) distilled water rinse. Initial ammonia levels ranged from 120 to 1,280 ppb (147-1,570 micrograms/m3). Acidic rinsing resulted in an immediate 90% reduction in exhaled ammonia in all subjects, and a return to 50% of baseline levels occurred within 1 h. Depletion that resulted from tooth brushing or distilled water alone was not significant. It was concluded that acidic oral rinsing is an effective method of reducing airway ammonia, but repeated oral rinsing may be required to maintain consistent, low-breath-ammonia conditions during acid aerosol exposure studies.     

Calcium acetate as a phosphorus binder in hemodialysis patients.

Much interest is currently centered on the use of calcium acetate as a phosphorus binder in patients with renal failure. Therefore, this compound in subjects previously stable on calcium carbonate and undergoing high-efficiency hemodialysis with a dialysate calcium of 2.5 mEq/L was evaluated. Twenty subjects were switched from generic calcium carbonate to a single calcium carbonate preparation for a period of 2 months. This was followed by a phase (1 month) in which calcium acetate was substituted for calcium carbonate at a dose containing half the amount of elemental calcium. Subjects then continued calcium acetate for 6 months. It was found that calcium acetate allowed comparable control of immunoreactive parathyroid hormone, calcium, and phosphorus levels compared with calcium carbonate. This occurred with half the amount of elemental calcium ingested in the form of calcium acetate (349 +/- 25 versus 699 +/- 75 mmol/day; P less than 0.001). With this lower dose, the overall incidence of hypercalcemia was the same with each formulation. In the eight subjects concurrently receiving i.v. calcitriol, the incidence of hypercalcemia was significantly higher during the first month of calcium acetate compared with that in those not receiving this compound (P less than 0.05). Of those four subjects receiving the high dose of calcitriol (2 micrograms thrice weekly), all required either reduction in the dose or discontinuation of the drug. Thus, mineral metabolism could be controlled adequately with calcium acetate despite using half as much elemental calcium compared with calcium carbonate. This, however, did not result in a lower incidence of hypercalcemia, particularly in those receiving i.v. calcitriol.     

Ischaemia-reperfusion injury and regional inflammatory responses in abdominal aortic aneurysm repair.

OBJECTIVES: The inflammatory response to abdominal aortic aneurysm repair is likely to result in response to an ischaemia-reperfusion injury (IRI) to the lower-limbs and gastrointestinal tract. This paper reviews the pathogenesis of the inflammatory response to abdominal aortic aneurysm repair, with specific reference to the levels of evidence in the current literature regarding the potential origin of the inflammatory response. DESIGN: Review article. METHODS: The current literature (1966 to August 2003) was reviewed specifically for all articles employing techniques of regional blood sampling from the venous drainage of the lower limbs or gastrointestinal tract during abdominal aortic aneurysm repair. RESULTS: Ten relevant studies were identified. These demonstrated that regional blood sampling techniques could be easily performed, and provided useful information regarding the potential sites of origin of the inflammatory response. CONCLUSIONS: Regional blood sampling techniques provide useful information regarding the potential sites of origin of the inflammatory response. Current evidence suggests that both the lower limbs and gastrointestinal tract are clearly important in their roles, however more work is now required to compare directly the roles and contributions of the lower limbs and gastrointestinal tract to the inflammatory response during abdominal aortic aneurysm repair.     

Combination of ABO blood group incompatibility and glucose-6-phosphate dehydrogenase deficiency: effect on hemolysis and neonatal hyperbilirubinemia

The incidence (%) of hyperbilirubinemia (serum bilirubin ≥257 μmol/l) was similar in neonates with a combination of ABO incompatibility and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency (45%), with ABO incompatibility (54%) or G-6-PD deficiency (37%), alone (ns). Carboxyhemoglobin values, corrected for inspired CO, were similarly elevated in all three groups (0.87 ± 0.32%, 0.82 ± 0.29%, 0.76 ± 0.18%, respectively, ns), but correlated with bilirubin only in those with ABO incompatibility alone. ABO-incompatible/G-6-PD-deficient neonates, compared with those with either condition alone, are not at increased risk for hemolysis or hyperbilirubinemia.     

Monkeypox virus detection in rodents using real-time 3'-minor groove binder TaqMan assays on the Roche LightCycler

During the summer of 2003, an outbreak of human monkeypox occurred in the Midwest region of the United States. In all, 52 rodents suspected of being infected with monkeypox virus were collected from an exotic pet dealer and from private homes. The rodents were euthanized and submitted for testing to the United States Army Medical Research Institute of Infectious Diseases by the Galesburg Animal Disease Laboratory, Illinois Department of Agriculture. The rodent tissue samples were appropriately processed and then tested by using an integrated approach involving real-time polymerase chain reaction (PCR) assays, an antigen-detection immunoassay, and virus culture. We designed and extensively tested two specific real-time PCR assays for rapidly detecting monkeypox virus DNA using the Vaccinia virus F3L and N3R genes as targets. The assays were validated against panels of orthopox viral and miscellaneous bacterial DNAs. A pan-orthopox electrochemiluminescence (ECL) assay was used to further confirm the presence of Orthopoxvirus infection of the rodents. Seven of 12 (58%) animals (seven of 52 (15%) of all animals) tested positive in both monkeypox-specific PCR assays and two additional pan-orthopox PCR assays (in at least one tissue). The ECL results showed varying degrees of agreement with PCR. One hamster and three gerbils were positive by both PCR and ECL for all tissues tested. In addition, we attempted to verify the presence of monkeypox virus by culture on multiple cell lines, by immunohistology, and by electron microscopy, with negative results. Sequencing the PCR products from the samples indicated 100% identity with monkeypox virus strain Zaire-96-I-16 (a human isolate from the Congo). These real-time PCR and ECL assays represent a significant addition to the battery of tests for the detection of various orthopoxviruses. In light of the recent monkeypox virus transmissions, early detection of the virus is crucial for both natural outbreaks and potential acts of bioterrorism.     

Mosaicism in amniotic fluid cell cultures: Classification and significance

The last decade has witnessed increasing application of human cytogenetic technology to prenatal chromosome analysis. However, unlike the rather uniform peripheral blood T-lymphocyte system which has provided most of our experience in human cytogenetics, long-term amniotic-fluid cell cultures display extreme cellular heterogeneity and disproportionate growth of certain cell types as a consequence of clonal amplification. When they enter cell culture, many of these cells are approching the terminal stages of their respective life spans and may have accumulated chromosomal aberrations. Concern about the possibility of true fetal mosaicism seems warranted chiefly in situations were multiple colonies display potentially viable aberrations. Clonal analysis, preferable of multiple clonal types, and attention to details of clonal morphology are likely to minimize diagnostic errors and undue apprehension resulting from mosaicism in amniotic-fluid cell cultures.     

Inefficient formation of a complex among CXCR4, CD4 and gp120 in U937 clones resistant to X4 gp120-gp41-mediated fusion

Certain subclones (designated as minus clones) of the promonocytic U937 cell line do not support efficient infection and fusion mediated by T cell line adapted (TCLA) X4 HIV-1 gp120-gp41 (Env) although the CXCR4 and CD4 concentrations at their surfaces are similar to those at the surfaces of clones susceptible to HIV-1 entry (plus clones) (H. Moriuchi et al., J. Virol. 71, 9664-9671, 1997). To test the hypothesis that inefficient formation of gp120-CD4-CXCR4 complexes could contribute to the mechanism of resistance to Env-mediated fusion in the minus clones, we incubated plus and minus cells with HIV-1 LAI gp120 and coimmunoprecipitated CD4 by using anti-CXCR4 antibodies. The gp120 induced inefficient coimmunoprecipitation of CD4 in the minus clones but not in the plus ones. Overexpression of CD4 resulted in significant restoration of the minus clones' susceptibility to fusion in parallel with an increase in the amount of the gp120-CD4-CXCR4 complexes. These results not only suggest that the resistance to TCLA X4 HIV-1 entry in the U937 minus clones is due to the inability of these cells to efficiently form complexes among CD4, gp120, and CXCR4, but also provide a direct evidence for the correlation between fusion and the cell surface concentration of the complexes among CXCR4, CD4, and gp120. These data and similar recent observations in macrophages suggest that inefficient complex formation among CXCR4, CD4, and gp120 could be a general mechanism of cell resistance to gp120-gp41-mediated fusion and a major determinant of HIV-1 evolution in vivo.     

Chronic toxicity and bioaccumulation of 2,5,2′,5′- and 3,4,3′,4′-tetrachlorobiphenyl and Aroclor® 1242 in the amphipodHyalella azteca

The addition of 100 (g/L of Aroclor^® 1242 (A1242) or 2,5,2,5-tetrachlorobiphenyl (TeCB) during 10 week chronic toxicity tests withHyalella azteca resulted in complete mortality. There were no effects on survival, growth, or reproduction after addition of 30 g/L. Toxic effects were observed at tissue levels of between 30 and 180 g/g on a wet weight basis, and tissue levels appear to be a better indicator of toxicity than levels in water. No toxic effects were observed after additions of up to 2,700 g/L of the coplanar congener 3,4,3,4-TeCB.H. azteca has the ability to avoid accumulating in excess of 140 g/g 3,4,3,4-TeCB. The amount taken up was proportional to the amount added in water up to 100 g/L, but was constant at higher additions, possibly accounting for its relatively low toxicity. The low toxicity of the coplanar congener, as compared to the non-coplanar 2,5,2,5-TeCB, is in direct contrast to the high toxicity of coplanar PCB congeners to mammals and may be associated with slower rates of aromatic hydrocarbon metabolism in amphipods. Polychlorinated biphenyl levels measured in amphipods from Lake Ontario are approximately 100-fold below levels associated with toxicity inH. azteca, but are above levels which, through biomagnification up the food chain, lead to salmonid residues in excess of 2 g/g, a tolerance limit for human consumption.