The effect of tridiphane (2-(3,5-dichlorophenyl)-2-(2,2,2-trichloroethyl)oxirane) on hepatic epoxide-metabolizing enzymes: indications of peroxisome proliferation

Administration of tridiphane (Tandem, DOWCO 356, 2-(3,5-dichlorophenyl)-2-(2,2,2-trichloroethyl)oxirane) to male Swiss-Webster mice for 3 days at 100, 250, and 500 mg/kg (ip) resulted in increases in liver weight accompanied by an increase in mitotic index and increases in large particle and microsomal protein. Epoxide hydrolase (EH) activity towards cis-stilbene oxide (CSO, microsomal EH) was elevated in microsomes and cytosol, a decrease in microsomal cholesterol EH was found, and hydrolysis of trans-stilbene oxide (TSO, cytosolic EH) was elevated in the cytosol but not in the microsomes. Glutathione S-transferase (GST) activity was elevated in cytosol for CSO, TSO, and 1,2-dichloro-4-nitrobenzene (DCNB), with inconsistent responses found with 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-epoxy-3-(p-nitrophenoxy)propane (ENPP). Microsomal GST was not consistently effected by tridiphane. Clofibrate (500 mg/kg, 3 daily ip injections) treatment resulted in similar responses in liver size, microsomal protein, and the EHs. The increase in cytosolic EH activity previously has been noted only in animals treated with peroxisome proliferators. Examination of livers from mice treated with 250 mg/kg tridiphane revealed that an increase in hepatic peroxisomes was apparent after 3 days of treatment. This was accompanied by decreases in serum cholesterol and triglyceride levels and increases in liver carnitine acetyl transferase and cyanide-insensitive oxidation of palmitoyl-CoA. This study demonstrates that tridiphane does have in vivo effects on mammalian epoxide-metabolizing enzymes and extends the association of increased cytosolic epoxide hydrolase activity with peroxisome proliferation.     

The Efficacy of DFO-HOPO,DTPA-DX and DTPA for Enhancing the Excretion of Plutonium and Americium from the Rat

Summary

A hydroxypridinone derivative of desferrioxamine (Na-DFO-HOPO), a dihydroxamic derivative of diethylenetriaminepenta-acetic acid (ZnNa-DTPA-DX), and DTPA (CaNa₃- and ZnNa₃-DTPA) were tested at dosages of 30 μmol kg^?1 for their ability to remove ²³⁸Pu or ²⁴¹Am from rats after their intravenous injection as citrate or inhalation as nitrate. The most effective treatment regimen for injected Pu was the repeated administration of DFO-HOPO; by 7 days the body content was reduced to 8% of that in untreated animals. Repeated dosages of 3 μmol kg^?1 DFO-HOPO were as effective as those of 30 μmol kg^?1 DTPA. After inhalation of Pu nitrate, repeated treatment with DTPA, DTPA-DX or DFO-HOPO reduced the body content by 7 days to, respectively, 10, 15 and 31% of those in untreated animals. After inhalation of Am, DTPA-DX and DTPA were equally effective, the body contents being reduced to 7% of control values with repeated treatment. Injection of DFO-HOPO was ineffective for enhancing the elimination of inhaled or injected Am. The results confirm the strategy of examining the use of siderophore analogues for the decorporation of Pu or Am. However, at present DTPA should remain the agent of choice, particularly after inhalation.     

Differential immune imprinting by influenza virus vaccination and infection in nonhuman primates

Immune memory of a first infection with influenza virus establishes a lasting imprint. Recall of that memory dominates the response to later infections or vaccinations by antigenically drifted strains. Early childhood immunization before infection may leave an imprint with different characteristics. We report here a comparison of imprinting by vaccination and infection in a small cohort of nonhuman primates (NHPs). We assayed serum antibody responses for binding with hemaglutinnins (HAs) both from the infecting or immunizing strain (H3 A/Aichi 02/1968) and from strains representing later H3 antigenic clusters (“forward breadth”) and examined the effects of defined HA mutations on serum titers. Initial exposure by infection elicited strong HA-binding and neutralizing serum antibody responses but with little forward breadth; initial vaccination with HA from the same strain elicited a weaker response with little neutralizing activity but considerable breadth of binding, not only for later H3 HAs but also for HA of the 2009 H1 new pandemic virus. Memory imprinted by infection, reflected in the response to two immunizing boosts, was largely restricted (as in humans) to the outward-facing HA surface, the principal region of historical variation. Memory imprinted by immunization showed exposure to more widely distributed epitopes, including sites that have not varied during evolution of the H3 HA but that yield nonneutralizing responses. The mode of initial exposure thus affects both the strength of the response and the breadth of the imprint; design of next-generation vaccines will need to take the differences into account.

Antigenic exposures determine the acquisition and development of adaptive immunity. The humoral response in a naive individual yields both antibody-secreting plasma cells that recognize the new antigen and memory B cells that can respond to future encounters with related antigens. The combination of these two components can confer long-lasting protection against antigenically stable pathogens. For antigenically diverse pathogens and those that evolve to evade immune pressure (e.g., influenza virus and HIV), serum responses often confer incomplete immunity to future variants (1, 2).The hemagglutinin (HA) and neuraminidase (NA) define the serotype of an influenza virus isolate (3). Antigenic shifts occur when novel animal influenza viruses can transmit to humans, spread rapidly, and initiate pandemics, owing to absence of any preexisting immunity (4, 5). Historically, the descendants of pandemic viruses have become endemic seasonal variants that undergo antigenic drift as they evolve over time to evade dominant human herd immunity (6, 7). For most adults, both processes have shaped human immunity to influenza.Immune memory causes a primary infection to impart an enduring imprint (8–11). Despite a lifetime of repeated exposures to divergent influenza viruses, the relative strength of an individual’s immune response to vaccination or infection correlates with the antigenic similarity of the vaccine or infecting strain to that person’s initial exposure. Until recently, the first encounter was invariably an infection. Because of recent changes in vaccine policy in the United States and Europe, infants and toddlers are now encouraged to receive influenza vaccines before they experience an influenza infection (12, 13). We have little information, however, about the immunological memory to influenza virus established when the primary exposure is vaccination rather than infection.Using nonhuman primates (rhesus macaques) as a model, we have examined how the mode of influenza exposure affects both primary and secondary antibody responses. We found that an initial exposure by infection elicited strong, strain-specific, HA-binding, and neutralizing serum antibody responses. Initial exposure by immunization with the HA protein from the strain used in the infection arm of the study elicited relatively weaker HA-binding responses that lacked neutralization potency but had greater interseasonal forward breadth. Subsequent exposures, by immunization, generated antibodies with increased interseasonal breadth in infected animals and neutralizing activity in the initially immunized monkeys. Initially infected macaques maintained responses that were strongly imprinted by the infecting strain, while those initially immunized with protein retained a serum repertoire that cross-reacted with heterologous HAs. Moreover, the distribution of epitopes bound by serum IgG was different in the two cases. These data suggest that the mode of HA exposure influences its immune imprint and that next-generation vaccine design will need to take this influence into account.     

The emergence of coryneform bacteria as a cause of nosocomial infections in compromised hosts

Corynebacterium species that are normally abundant on the skin and mucous membranes rarely cause infections and are susceptible to most antibiotics. The report in 1976 of four cases of sepsis at the National Institutes of Health caused by a hitherto undescribed Corynebacterium that is highly antibiotic resistant, but uniformly susceptible to vancomycin, alerted the medically oriented scientific community to the emergence of these organisms as a possible new cause of nosocomial infections. Although we have always performed antibiotic susceptibility tests on all microorganisms recovered from normally sterile body fluids, our first recovery of these organisms was in August 1977. Since then we have recovered 52 such strains from 39 patients, most frequently from the rectum, followed by the groin, blood, lesions and urine in order of predominance. Characterization by API 50 L strips revealed that most, but not all strains resemble the JK group of Riley et al. [1]. Cell wall studies and DNA base ratios further confirmed their status as corynebacteria. Hospital acquisition has been proved; cross infection between patients is the most likely mode of spread. Their recognition is necessary for optimal preventive and therapeutic care of patients with compromised host defenses.     

Comparison of a parasite lactate dehydrogenase-based immunochromatographic antigen detection assay (OptiMAL) with microscopy for the detection of malaria parasites in human blood samples

Microscopic examination of blood smears remains the gold standard for malaria diagnosis, but is labor-intensive and requires skilled operators. Rapid dipstick technology provides a potential alternative. A study was conducted in The Gambia to compare the performance of OptiMAL, an immunochromatographic antigen detection assay for the diagnosis of malaria using parasite lactate dehydrogenase, against standard microscopy in patients with suspected malaria. For initial diagnosis of Plasmodium falciparum, irrespective of stage, this assay had a sensitivity of 91.3%, a specificity of 92%, a positive predictive value of 87.2%, and a negative predictive value of 94.7%. The sensitivity of the test decreased markedly at parasitemias < 0.01%. This assay can be used for the diagnosis of malaria in areas where microscopy is not available and for urgent malaria diagnosis at night and at weekends, when routine laboratories are closed and when relatively inexperienced microscopists may be on duty.     

Comparison of gastric mucosal blood flow as determined by aminopyrine clearance and gamma-labeled microspheres.

Gastric mucosal blood flow was simultaneously determined by aminopyrine clearance and gamma-labeled microspheres (15 +/- 5 mu in diameter) in anesthetized dogs prepared with a chambered segment of stomach greater curvature. Paired flow measurements were made in 11 dogs (n = 28) secreting in response to intravenous histamine (1mug per kg per min), in 11 (n = 21) nonsecreting dogs given intravenous isoproterenol (0.5 or 1.0 mug per kg per min), and in 9 (n = 10) dogs given no drugs to stimulate secretion or blood flow (resting dogs). Eight additional injections were done in dogs receiving various combinations of isoproterenol and histamine. Isotonic HCl was maintained on the mucosal surface during all experiments. Regression analysis demonstrated a highly significant linear correlation between clearance and microsphere-measured flow in the histamine (P less than 0.001, r = 0.96) and isoproterenol (P less than 0.001, r = 0.78) experiments, with clearance averaging 83% of microsphere flow during histamine stimulation but only 25% during isoproterenol. The relationship between clearance and microsphere flow was not significantly different for the resting and isoproterenol experiments. Mucosal perfusion measured by microspheres was about 5 times the resting value for both histamine and isoproterenol-stimulated dogs. Perfusion calculated from aminopyrine clearance averaged 46, 38, and 90% of the microsphere value in the resting, isoproterenol, and histamine experiments, respectively. Pooled data from secreting dogs demonstrated a fairly constant ratio of microsphere-measured flow to clearance (1.25 +/- 0.06 mean +/- SEM), regardless of the secretory rate. Our results indicate that aminopyrine clearance reflects only a small fraction of mucosal blood flow in the nonsecreting stomach, even in the presence of exogenous acid.     

Effects of repeated heating on human albumin

Abstract. Solutions of stabilized 5 and 25% Normal Serum Albumin (Human) fractionated from plasma, placentas, and blends of these sources were subjected to repeated heatings for 120 h at 56 °C, interspersed with storage for 48 h at 4°C. Disc electrophoretic analyses showed that heating some solutions produced a reversible dimerization of the albumin related to the source, protein concentration, and number of heatings. Cellulose acetate electrophoresis showed that repeated heating produced a reduction in the amount of albumin with the formation of a component with a mobility slower than that of albumin. After eight heatings plasma albumin gelled; albumin from placental-plasma blends partially gelled; there was no gelation of placental albumin after nine heatings.     

The response of Gastric Inhibitory Polypeptide (GIP) and insulin to glucose in duodenal ulcer patients

Summary The response of Gastric Inhibitory Polypeptide (GIP) and insulin to a 50 g oral glucose tolerance test (OGTT) and an intravenous glucose infusion (IVGI), which copied the changes in plasma glucose concentrations during the OGTT, were measured in 10 patients with duodenal ulcer and in 10 healthy control subjects. The mean responses of GIP and insulin to OGTT were significantly increased in the ulcer patients. During IVGI the responses were normal. The degree of increased GIP response in the patients was positively correlated with the plasma glucose increase during the OGTT. It is postulated that the increased GIP secretion is related to a faster glucose absorption due to rapid gastric emptying in duodenal ulcer patients. No correlation was found between basal and peak gastric acid output and the GIP response in the patients. The data demonstrate that GIP secretion is not defective in duodenal ulcer patients.