The rapid Bethesda assay is equivalent to the standard Bethesda assay for detection of factor IX inhibitors in patients with severe haemophilia B

INTRODUCTION

The time-dependent nature of factor VIII (FVIII) inhibitors is well described, and the standard FVIII Bethesda assay used to measure inhibitors incorporates a 2-hour incubation. Despite case reports and reviews describing the immediate-acting nature of factor IX (FIX) inhibitors, many coagulation laboratories continue to use a traditional prolonged incubation for FIX Bethesda assays. To our knowledge, a comprehensive evaluation of the FIX Bethesda assay without incubation has not been reported.

AIM

The goal of this study was to evaluate the performance of a rapid FIX Bethesda (ie no incubation) compared with the standard Bethesda assay (2-hour incubation).

METHODS

The analysis used a Bethesda assay configured for either immediate testing or a 2-hour incubation. Samples from 14 haemophilia B patients with inhibitors and 9 non-human controls were tested.

RESULTS

The two assays yielded similar performance overall. The average per cent difference in inhibitor titre between the rapid and standard FIX Bethesda assay was -3% (range -15% to +13%; P = .175) for patient samples and -2% (range -17% to +14%; P = .376) for controls.

CONCLUSION

The rapid Bethesda assay showed good agreement with the standard Bethesda assay for determination of inhibitor levels in patients with severe haemophilia B. The rapid assay allows for faster assessment of inhibitors in patients with severe haemophilia B and has the potential to improve the ability of the coagulation laboratory to perform testing from a logistical viewpoint. Further studies involving larger numbers of patients would be important to confirm our findings.

Exposure to organic and inorganic traffic-related air pollutants alters haematological and biochemical indices in albino mice Mus musculus

The relationship between air pollution exposure and haematology remains controversial. Evidences in the effect of trace organic air pollutants and in the impact of such exposure on lipid and protein levels are scarce. This work investigated the health effects of medium-term exposure to traffic-related air pollution on both haematological and biochemical indices in animal models. Two groups of albino mice (Mus musculus) were exposed to ambient air polluted by vehicle exhaust for three and six months, and one group was kept as control. Results found significant depletions (p < 0.05) in red blood cells, packed cell volume, neutrophils, eosinophils, monocytes, and total cholesterol after air pollution exposure. On the contrary, significant elevations (p < 0.05) were observed in platelet, lymphocytes, and serum albumin compared to control condition. Correlation data suggested that significant changes in blood parameters may be altered by the synergistic effect of several organic and inorganic air pollutants.

Social hierarchy position in female mice is associated with plasma corticosterone levels and hypothalamic gene expression

Social hierarchies emerge when animals compete for access to resources such as food, mates or physical space. Wild and laboratory male mice have been shown to develop linear hierarchies, however, less is known regarding whether female mice have sufficient intrasexual competition to establish significant social dominance relationships. In this study, we examined whether groups of outbred CD-1 virgin female mice housed in a large vivaria formed social hierarchies. We show that females use fighting, chasing and mounting behaviors to rapidly establish highly directionally consistent social relationships. Notably, these female hierarchies are less linear, steep and despotic compared to male hierarchies. Female estrus state was not found to have a significant effect on aggressive behavior, though dominant females had elongated estrus cycles (due to increased time in estrus) compared to subordinate females. Plasma estradiol levels were equivalent between dominant and subordinate females. Subordinate females had significantly higher levels of basal corticosterone compared to dominant females. Analyses of gene expression in the ventromedial hypothalamus indicated that subordinate females have elevated ERα, ERβ and OTR mRNA compared to dominant females. This study provides a methodological framework for the study of the neuroendocrine basis of female social aggression and dominance in laboratory mice.

A comparative study on effects of static electric field and power frequency electric field on hematology in mice

With the development of the ultra high voltage transmission technology, the voltage level of transmission line rised. Accordingly, the strength of electric field in the vicinity of transmission line increased, thus possible health effects from electric field have caused many public attentions. In this study, in order to compare effects induced by static electric field (SEF) and power frequency electric field (PFEF) on immune function, Institute of Cancer Research (ICR) mice were exposed to 35 kV/m SEF (0 Hz) and PFEF (50 Hz),respectively. Several indicators of white blood cell, red blood cell as well as hemoglobin in peripheral blood were tested after exposure of 7, 14 and 21 days, respectively. There was no significant difference in any indicators under SEF exposure of 35 kV/m for 7d, 14d and 21d between experimental group and control group. Under the PFEF exposure of 35 kV/m, white blood cell count significantly reduced after exposure of 7d, 14d and 21d. Meanwhile, red blood cell count significantly reduced after exposure of 7d, and returned to normal level through the compensatory response of organism after exposure of 14d and 21d. Hemoglobin concentration significantly decreased only after exposure of 21d. Based on tested results of hematological indicators, SEF exposure of 35 kV/m did not affect immune functions in mice but PFEF exposure of 35 kV/m could cause a decline of immune function. This difference of effects from SEF and PFEF on immune function was possibly caused by the difference of the degree of molecular polarization and ion migration in organism under exposure of two kinds of electric fields.

Discovery of natural mouse serum derived HIV-1 entry inhibitor(s)

Among rationally designed human immunodeficiency virus 1 (HIV-1) inhibitors, diverse natural factors have showed as potent anti-HIV activity in human blood. We have discovered that the boiled supernatant of healthy mouse serum could suppress HIV-1 entry, and exhibited reduced inhibitory activity after trypsin digestion. Further analysis demonstrated that only the fraction containing 10-25 K proteins could inhibit HIV-1 mediated cell-cell fusion. These results suggest that the 10-25 K protein(s) is novel natural HIV-1 entry inhibitor(s). Our findings provide important information about novel natural HIV entry inhibitors in mouse serum.

Effects of Embryo Transfer on Emotional Behaviors in C57BL/6 Mice

Microbiologic standardization plays a key role in the management of animal facilities because contamination of stock could affect the health status and wellbeing of animals and thereby induce artifacts in biomedical research. One common method to avoid the dissemination of pathogens is embryo transfer (ET). Although disturbances in the perinatal environment may cause long-lasting effects on the behavior and physiology of mouse offspring, the influences of ET during this sensitive phase have not yet been addressed. Our study investigated the effects of various components of ET (anesthesia, surgery, recipient strain) on the behavior of dams (exploration, nest-building) and offspring (nest-building, exploration, anxiety, and social and depressive-like behaviors). For ET, the donor strain C57BL/6N and a standard protocol were used. Whereas treatment with anesthesia-analgesia did not affect maternal behavior, female offspring demonstrated overall effects on weight gain and corticosterone levels. Compared with naturally delivered female offspring, dams obtained through ET demonstrated decreased exploration and nest-building. In addition, female ET-derived offspring had enhanced levels of anxiety and increased social interest. Furthermore, ET-derived dams obtained by using NMRI as the recipient strain showed increased exploratory behavior compared with that of dams obtained by using C57 mice as recipients. Compared with using C57 as recipients, both sexes of offspring transferred into NMRI recipients weighed more, and female mice showed a depressive-like phenotype. Our findings suggest that ET, now considered to be a routine procedure in animal husbandry, bears the risk of introducing artifacts.

Comparison of Submental Blood Collection with the Retroorbital and Submandibular Methods in Mice (Mus musculus)

Nonterminal blood sample collection of sufficient volume and quality for research is complicated in mice due to their small size and anatomy. Large (>100 μL) nonterminal volumes of unhemolyzed or unclotted blood currently are typically collected from the retroorbital sinus or submandibular plexus. We developed a third method-submental blood collection-which is similar in execution to the submandibular method but with minor changes in animal restraint and collection location. Compared with other techniques, submental collection is easier to perform due to the direct visibility of the target vessels, which are located in a sparsely furred region. Compared with the submandibular method, the submental method did not differ regarding weight change and clotting score but significantly decreased hemolysis and increased the overall number of high-quality samples. The submental method was performed with smaller lancets for the majority of the bleeds, yet resulted in fewer repeat collection attempts, fewer insufficient samples, and less extraneous blood loss and was qualitatively less traumatic. Compared with the retroorbital technique, the submental method was similar regarding weight change but decreased hemolysis, clotting, and the number of overall high-quality samples; however the retroorbital method resulted in significantly fewer incidents of insufficient sample collection. Extraneous blood loss was roughly equivalent between the submental and retroorbital methods. We conclude that the submental method is an acceptable venipuncture technique for obtaining large, nonterminal volumes of blood from mice.

Practical murine hematopathology: a comparative review and implications for research

Hematologic parameters are important markers of disease in human and veterinary medicine. Biomedical research has benefited from mouse models that recapitulate such disease, thus expanding knowledge of pathogenetic mechanisms and investigative therapies that translate across species. Mice in health have many notable hematologic differences from humans and other veterinary species, including smaller erythrocytes, higher percentage of circulating reticulocytes or polychromasia, lower peripheral blood neutrophil and higher peripheral blood and bone marrow lymphocyte percentages, variable leukocyte morphologies, physiologic splenic hematopoiesis and iron storage, and more numerous and shorter-lived erythrocytes and platelets. For accurate and complete hematologic analyses of disease and response to investigative therapeutic interventions, these differences and the unique features of murine hematopathology must be understood. Here we review murine hematology and hematopathology for practical application to translational investigation.

Using dried blood spot sampling to improve data quality and reduce animal use in mouse pharmacokinetic studies

Traditional pharmacokinetic analysis in nonclinical studies is based on the concentration of a test compound in plasma and requires approximately 100 to 200 μL blood collected per time point. However, the total blood volume of mice limits the number of samples that can be collected from an individual animal-often to a single collection per mouse-thus necessitating dosing multiple mice to generate a pharmacokinetic profile in a sparse-sampling design. Compared with traditional methods, dried blood spot (DBS) analysis requires smaller volumes of blood (15 to 20 μL), thus supporting serial blood sampling and the generation of a complete pharmacokinetic profile from a single mouse. Here we compare plasma-derived data with DBS-derived data, explain how to adopt DBS sampling to support discovery mouse studies, and describe how to generate pharmacokinetic and pharmacodynamic data from a single mouse. Executing novel study designs that use DBS enhances the ability to identify and streamline better drug candidates during drug discovery. Implementing DBS sampling can reduce the number of mice needed in a drug discovery program. In addition, the simplicity of DBS sampling and the smaller numbers of mice needed translate to decreased study costs. Overall, DBS sampling is consistent with 3Rs principles by achieving reductions in the number of animals used, decreased restraint-associated stress, improved data quality, direct comparison of interanimal variability, and the generation of multiple endpoints from a single study.

Rapid quantification of resveratrol in mouse plasma by ultra high pressure liquid chromatography (UPLC) coupled to tandem mass spectrometry

OBJECTIVE

The objective of this study was to develop a rapid and sensitive method for the quantification of resveratrol, a polyphenolic compound with multiple health beneficial effects, in mouse plasma.

METHODS

We used reversed-phase ultra high pressure-liquid chromatography with tandem mass spectrometry detection for the determination of resveratrol levels in mouse plasma. An Agilent Zorbax Eclipse Plus C18 column (2.1 mm x 50 mm, 1.8 μm) was used as the stationary phase. The mobile phase consisted of a gradient formed using 1 mM ammonium fluoride and methanol.

RESULTS

Using this improved method, we obtained a retention time of 2.2 min and a total run time of 5 min, for resveratrol. The calibration curve for resveratrol showed a linear range from 0.5 to 100 ng/mL. The average coefficient of variation was 6% for interday variation and 4% for intraday variation. The recovery for resveratrol in mouse plasma was 85 ± 10% (mean ± standard deviation).

CONCLUSION

The method presented herein allows a rapid and very sensitive quantification of resveratrol in mouse plasma at concentrations as low as 500 ppt.

Genotoxic effects in blood cells of Mus musculus and Iguana iguana living near coal mining areas in Colombia

Coal is a mixture of chemicals with the capacity of promoting biochemical changes that may lead to DNA damage. In this study, the comet assay in peripheral blood cells, and the micronucleus test in blood smears were used to evaluate potential genotoxic effects derived from exposure to coal mining activities on wild populations of Mus musculus and Iguana iguana. Four locations from Colombia were evaluated: La Loma and La Jagua de Ibirico, two municipalities located near coal mining fields at the Department of Cesar; and Valledupar and Arjona, cities used as reference sites, both localized at least 100 and 200km far from the mines, respectively. Compared to Valledupar and Arjona, animals collected in close proximity to coal mining areas showed highest percentages of DNA damage for both species, evidencing that living around coal mining fields may result in an increase of DNA lesions in blood cells of rodents and reptiles. The results for micronucleus test were conflicting. Mice from Arjona had greater number of cells with micronucleus than those from the other studied locations, probably as a result of infection found by blood parasites. In summary, it was demonstrated that animals living around coal mining areas have a greater chance of having DNA damage, as measured by the comet assay, than those from sites far from the coal dust source.

Euthanasia by CO₂ inhalation affects potassium levels in mice

We and others frequently have noted serum potassium levels of 8.0 +/- 0.85 mEq/L or greater in laboratory mice; this concentration has even been published as the upper limit of a 'normal' reference range. However, if bone fide, this potassium concentration would be incompatible with life in all species. We investigated conditions frequently encountered in the research setting to distinguish artifactual from true hyperkalemia. Variables evaluated included site of collection, time allowed for clot formation before serum separation, time elapsed between collection and analysis of samples collected in a serum separator tube, precollection method of anesthesia, and euthanasia technique. Serum potassium was measured from 75 C57BL/6NTac 10-wk-old female mice and divided into at least 5 mice per variable. Animals were euthanized by exsanguination immediately after terminal CO₂ or ketamine-xylazine (KX) administration. Mice euthanized with CO₂ had higher mean serum potassium (7.0 +/- 0.5 mEq/L) and range serum potassium (6.0 to 8.1 mEq/L) than did KX-treated mice. CO₂ inhalation resulted in significantly lower blood pH (6.9 +/- 0.1), higher pCO₂ (153.3 +/- 38.8 mm Hg), and higher lactate levels (3.9 +/- 0.9 mmol/L) than did KX anesthesia followed by exsanguination. These results suggest that antemortem respiratory acidosis from CO₂ administration causes artifactual hyperkalemia in mice. Therefore, blood collection under KX anesthesia is preferable over CO₂ inhalation to obtain accurate potassium values from mice.

[Comparison of hemogram changes under chronic intermittent hypoxia in Lasiopodomys mandarinus and Kunming Mus musculus]

Mandarin vole (Lasiopodomys mandarinus) spends almost all of its life underground and must have evolved remarkable adaptations to cope with the subterranean hypoxic stress. The aim of present study is to explore the adaptation mechanism through the comparison of hemogram changes under chronic intermittent hypoxia in Mandarin vole and Kunming (KM) mouse (Mus musculus). Mandarin vole and KM mouse were treated with chronic intermittent hypoxia (10.0% oxygen), which was maintained by an oxygen cabin, for 4 h per day during four weeks. Then blood samples from the animals with and without hypoxia treatment were analyzed by a hematology analyzer. The results showed that under normoxic condition mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), white blood cell count (WBC) and platelet (PLT) in Mandarin vole were significantly lower than those in KM mouse. On the contrast, red blood cell count (RBC) and mean corpuscular hemoglobin concentration (MCHC) in Mandarin vole were higher than that in KM mouse. After four-week chronic intermittent hypoxia treatment, the hemogram changes were as following. MCV and HCT were elevated in Mandarin vole, not affected in KM mouse. Both hemoglobin (HGB) content and MCH in KM mouse increased, while only MCH increased in Mandarin vole. No obvious changes of WBC and PLT were found in two species. These results suggest that the adaptive mechanism of blood system in Mandarin vole responding to hypoxic conditions is different from that of KM mouse. As a subterranean vole, the Mandarin vole has a better tolerance to hypoxia.

Blood parasites of mound-building mouse, Mus spicilegus Petényi, 1882 (Mammalia, Rodentia)

Mound-building mice, Mus spicilegus, were studied for the blood parasites in Eastern Slovakia, vicinity Kechnec village near Kosice town (Kosická kotlina basin, 21 degrees 14' E, 48 degrees 33' N) during years 2002-2005. Overall, 251 specimens were examined. The parasites were detected using microhematokrit centrifugation technique and on the Giemsa's method stained blood smears and light microscopy. The parasites were found in 3.57% of specimens; 1.20% of mice were infected with Bartonella sp., 2.39% were infected with Babesia piroplasms. No Hepatozoon hemogregarines and trypanosomes were observed. The intensity of infection with Bartonella was low, less than 0.01% of erythrocytes were invaded, the percent of the erythrocytes with Babesia sp. was less than 0.01%. The morphological description and measurements of parasites were made using the "Analysis" software combined with a video camera and a microscope. The mean size of Bartonella sp. bacteria's were 0.8 x 0.3 microm, range 0.4-1.5 x 0.1-0.9 microm, Babesia sp. occurred in pear-shaped and ring-like forms, 1.00-1.27 microm in diameter, and 0.98-1.27 microm in size, respectively. The regular form of four cells--"maltese cross" was not noticed. This is the first record infection of Mus spicilegus with blood parasites.

Columbin inhibits cholesterol uptake in bloodstream forms ofTrypanosoma brucei-A possible trypanocidal mechanism

The diterpenoid furanolactone (columbin) from Aristolochia albida inhibited growth of culture forms of Trypanosoma brucei. In vitro analysis of the compound at 5-250 microg/ml showed complete lysis of the parasites within 10-20 minutes post incubation. At 50 microg/ml, columbin killed about 50% of the parasites which initially appeared swollen under phase contrast microscopy. Also the total amount of cholesterol diminished dose-dependently in the presence of 10-100 microg/ml of columbin after a 3-day incubation period. In vivo analysis of the compound in T. brucei-infected mice revealed that 25 mg/kg administered for 3 consecutive days, completely cleared the parasites from the peripheral circulation. However, columbin could not clear parasites in the cerebrospinal fluid.

HPLC method for the pharmacokinetics and tissue distribution of taspine solution and taspine liposome after intravenous administrations to mice

Taspine is a bioactive aporphine alkaloid, which has many potent pharmacological effects. A simple, rapid HPLC method to quantify taspine in mouse plasma and tissue homogenates containing either taspine solution or liposome was developed and validated. Sample preparation was achieved by liquid-liquid extraction with acetoacetate. Taspine was separated on a C(18) reversed phase HPLC column, and quantified by its absorbance at 245 nm. The pharmacokinetics and tissue distribution after intravenous administrations of taspine liposome (L-Ta) and taspine solution (Ta) to ICR mice were then compared. The area under the plasma concentration-time curve (AUC) was higher for L-Ta than for Ta. In contrast, the total body clearance (CL), apparent volume of distribution V(c) and plasma half-life for the distribution (t(1/2 alpha)) and elimination phase (t(1/2 beta)) were lower for L-Ta, in comparison to the respective parameter of Ta. The AUC values were higher in the lung than in other organs for both L-Ta and Ta. The AUC in the spleen, kidney and liver of L-Ta were higher than those of Ta. However, the heart and brain AUC of Ta was higher than that of L-Ta. It can thus be concluded that incorporation into liposomes prolonged taspine retention within the systemic circulation, increased its distribution to the spleen and liver but reduced its distribution to the heart and brain.

Cordycepin induced eryptosis in mouse erythrocytes through a Ca2+-dependent pathway without caspase-3 activation

Cordyceps sinensis is a prized traditional Chinese medicine and its major component cordycepin is found to have anti-leukemia activities. However, its cytotoxicity in erythrocytes was unclear. To examine the effect of cordycepin on the induction of eryptosis (an apoptosis-like process in enucleated erythrocytes), flow cytometric assays based on membrane integrity and asymmetry were employed. For comparison, analyses were performed in parallel with two other anti-leukemia agents, indirubin 3'-monoxime (IDM) and As2O3. We found that at the IC50 against leukemia HL-60, cordycepin elicited eryptosis while IDM and As2O3 showed no erythrotoxicity in mouse erythrocytes. Mechanistically, cordycepin increased the [Ca2+]i and activated mu-calpain protease in a dose-dependent manner. Yet, no caspase-3 activation was observed in the cordycepin-treated erythrocytes. When extracellular Ca2+ was depleted, both the cordycepin-induced eryptosis and mu-calpain cleavage were suppressed. Our study therefore demonstrated for the first time that cordycepin induces eryptosis through a calcium-dependent pathway in the absence of mitochondria and caspase-3 activation.

Establishment of blood analyte intervals for laboratory mice and rats by use of a portable clinical analyzer

Portable clinical analyzers are currently used in human and veterinary medicine for diagnostic testing and blood monitoring; however, normal values for mice and rats of varying genetic backgrounds have not previously been reported. Blood was collected from unanesthetized mice (n = 131) and rats (n = 76) into lithium heparin tubes for analysis using E6+ cartridges for the portable analyzer. Results of glucose, blood urea nitrogen (BUN), sodium, potassium, chloride, hematocrit, and hemoglobin were compared to published ranges provided by a contract diagnostic laboratory. Analyzer ranges were computed as the mean +/- 2 standard deviations of the test samples, such that approximately 95% of tested animals would fall within the resultant range. The degree of overlap between analyzer and published ranges, or the percentage of the published range contained within the analyzer range, was calculated for all analytes. For mice, the ranges of 5 of 7 analytes had more than 57% overlap; for rats, ranges for 6 of 7 analytes had over 65% overlap. After the establishment of normal ranges, the analyzer was used to confirm hyperglycemia in Type I diabetic mice and elevated BUN in rats with induced glomerulosclerosis. The portable analyzer can be a valuable screening tool for both phenotyping and clinical care of rodents, with potential for investigations of both spontaneous and experimental disease in laboratory rodents.

Complete blood count, clinical chemistry, and serology profile by using a single tube of whole blood from mice

Clinical pathology is a valuable means for assessing specific organ pathology and a screening tool for general animal health. Routine clinical pathology evaluation in mice usually includes whole blood for a complete blood count (CBC) and a clinical biochemistry analysis. Acquisition and analysis of these samples can be problematic due to the small volumes of blood that can be obtained from a mouse. Typically, a complete blood count requires blood from a tube containing an anticoagulant, whereas a clinical biochemistry profile needs blood from a serum clot tube. Because of the small volume that can be obtained, splitting the blood from a single mouse into 2 different tubes may result in inadequate samples to perform the desired tests or introduce inaccuracies. We explored the feasibility of using a single lithium heparin tube for generation of a CBC, biochemistry profile, and serology profile. We also evaluated the consistency of CBC data, including the quality of a peripheral blood smear taken from a lithium heparin or EDTA tube after various storage times. We found that CBC, biochemistry, and serology profiles could be obtained more readily when blood samples were placed in a single lithium heparin tube than in 2 separate tubes. In addition, the quality of blood smears and CBC results from the lithium heparin tube were comparable (with few exceptions) to those from an EDTA tube after prolonged storage.

Recombinant galectins of male and female Haemonchus contortus do not hemagglutinate erythrocytes of their natural host

Recombinant galectins of female and male adult worms of Haemonchus contortus were expressed in Escherichia coli and their hemagglutinating activities to human and different animal erythrocytes were analyzed. The results showed that female and male galectins could be highly expressed in E. coli using a temperature-sensitive plasmid, with the recombinant protein being mainly appeared in inclusion bodies. Hemagglutinating activity assays showed that both of the galectins hemagglutinated human A, B, O type, dog, rabbit, chicken and mouse erythrocytes at the high concentration of 40 microg/well, but did not hemagglutinate erythrocytes of the natural host of H. contortus, the goat. Sugar inhibition assays confirmed that, out of eight sugars tested, only lactose was effective to inhibit agglutination of human type B erythrocytes by the recombinant galectins.

Detection of haematologic effects of mosquito biting using an animal model

The studies on haematologic changes in humans or animals as a result of mosquito bites are few. This study was undertaken to examines changes in the blood picture of mice (Mus musculus) exposed to Culex pipiens biting. Mice exposed to mosquito bites either once or twice (with 7 days between the two bites) showed insignificantly higher (P >0.05) counts of the total blood cells, platelets and hemoglobin content than normal mice with the highest level (11 %) was in WBCs following the second bite. Mosquito biting exerts its effects largely upon the differential WBCs. Exposure of mice once or twice to mosquito bites resulted in increased numbers of the 5 WBC types. Compared to control mice cells, the highest (P<0.01) levels of basophils (7.19-fold, 72.02 cells/ul), eosinophils (3.59-fold, 216.06 cells/ ul), monocytes (1.34-fold, 288.08 cells/ul) & lymphocytes (1.29 -fold, 1833.74 cells/ul) were after the second bite. Segmented neutrophils significantly (P<0.01) decreased by 2% & 5% of the normal mice count following first and second bite, respectively.

Individual mouse analysis of the cellular immune response to tumor antigens in peripheral blood by intracellular staining for cytokines

Among the experimental animal models, mice remain the most widely used for the evaluation of immunotherapeutic strategies. Vaccines against parasites and viral antigens are commonly administered to the appropriate mouse strain which also allows testing of the therapeutic effect. Similarly, in mice transgenic for human tumor associated antigens (TAA), cancer vaccines must lead to breakage of immune tolerance to elicit a significant effect on the tumor. However, one of the major drawbacks in the monitoring of cellular immune responses induced by vaccination is that functional immunological assays require suppression of the animals to collect the spleen or lymph nodes for analysis. Here, we report the application of a rapid intracellular staining (ICS) method to quantify antigen-specific T cells responses in small volumes of murine blood. Genetic vaccination with plasmid DNA followed by electroporation (DNA-EP) and the use of adenoviral vectors (Ad) encoding CEA as a model target antigen were applied to different strains of mice. Optimal blood volume, number of lymphocytes, sensitivity and reproducibility of intracellular staining for IFN-gamma were determined both in non-tolerant/wild type mice as well as in tolerant CEA transgenic mice upon restimulation of PBMCs with CEA peptides. Groups of vaccinated mice were then sacrificed and PBMCs and splenocytes from individual animals were compared for intracytoplasmic detection of IFN-gamma and TNF-alpha. A significant correlation was observed between splenic and blood immune responses. Finally, the cellular immune response was followed over time in groups of vaccinated mice. The kinetics of IFN-gamma producing effectors were measured after priming and successive boosting with adenoviral vectors. We show that intracellular staining for mouse PBMCs is a rapid and simple method to measure antigen-specific immune responses. It does not require animal euthanasia and mirrors the response observed in lymphoid organs such as the spleen.

The effect of different doses of cisplatin on the pharmacokinetic parameters of cefepime in mice

The simulation of human serum levels is essential in animal models to extrapolate the experimental results to clinical practice. Administration of a nephrotoxic drug such as cisplatin can be used to cause renal dysfunction as an approach to mimic human serum levels of renally excreted drugs. We aimed to determine the dose of cisplatin that did not affect the survival rate of mice and to achieve human-like serum concentrations of cefepime. Different doses of cisplatin (0, 10, 14, 18, 22 and 26 mg/kg) were given by intraperitoneal (i.p.) injection to mice three days prior to the i.p. administration of 80 mg/kg cefepime. With cisplatin doses of 18 and 22 mg/kg, the half-life of cefepime was significantly prolonged (P < 0.001) and all mice survived. The pretreatment with 26 mg/kg cisplatin significantly decreased survival (P = 0.001), but the half-life of cefepime was not significantly longer than of 18 mg/kg cisplatin. Serum levels of cefepime after the pretreatment with 18 mg/kg cisplatin were comparable to published human data. The administration of cisplatin appears to be a suitable method in mice for simulating human serum concentrations of renally excreted drugs.

Evaluation of antigen panels for ELISA monitoring of mouse colonies for antibodies to Pasteurellaceae

Pasteurellaceae infection in mice may be monitored by the detection of serum antibody using enzyme-linked immunosorbent assay (ELISA). We re-evaluated our standard antigen panel comprising Pasteurella pneumotropica and a V-factor requiring Haemophilus species (strain H21) by studying their serological relationship with Actinobacillus muris and 'Haemophilus influenzae-murium'. Serologically, A. muris and 'H. influenzae-murium' were found to be unrelated and to differ from P. pneumotropica and Haemophilus strain H21. These four antigens were used for monitoring breeding and experimental mouse colonies for a period of four years. The addition of 'H. influenzae-murium' antigen to the standard panel of antigens significantly increased the proportion of sera and serum panels showing anti-Pasteurellaceae antibody activity, but the addition of A. muris antigen did not.

Maximal oxygen consumption in relation to subordinate traits in lines of house mice selectively bred for high voluntary wheel running

We studied relations between maximal O2 consumption (VO2 max) during forced exercise and subordinate traits associated with blood O2 transport and cellular respiration in four lines of mice selectively bred for high voluntary wheel running (S lines) and their four nonselected control (C) lines. Previously, we reported VO2 max of 59 females at three Po2 (hypoxia = 14% O2, normoxia = 21%, hyperoxia = 30%). Here, we test the hypothesis that variation in VO2 max can be explained, in part, by hemoglobin concentration and Po2 necessary to obtain 50% O2 saturation of Hb (an estimate of Hb affinity for O2) of the blood as well as citrate synthase activity and myoglobin concentration of ventricles and gastrocnemius muscle. Statistical analyses controlled for body mass, compared S and C lines, and also considered effects of the mini-muscle phenotype (present only in S lines and resulting from a Mendelian recessive allele), which reduces hindlimb muscle mass while increasing muscle mass-specific aerobic capacity. Although S lines had higher VO2 max than C, subordinate traits showed no statistical differences when the presence of the mini-muscle phenotype was controlled. However, subordinate traits did account for some of the individual variation in VO2 max. Ventricle size was a positive predictor of VO2 max at all three Po2. Blood Hb concentration was a positive predictor of VO2 max in S lines but a negative predictor in C lines, indicating that the physiological underpinnings of VO2 max have been altered by selective breeding. Mice with the mini-muscle phenotype had enlarged ventricles, with higher mass-specific citrate synthase activity and myoglobin concentration, which may account for their higher VO2 max in hypoxia.

Study and culture of haematopoietic progenitor cells from peripheral blood in rats, hamsters and mice

The aim of this work was to isolate and cultivate a subpopulation of pluripotent stem cells present in peripheral blood of different animal species, frequently used in laboratory studies (mice, rats and hamsters). Pluripotent stem cells (PSCs), already described in human beings, are fibroblast-like cells that exhibit a CD34 marker, specific for haematopoietic stem cells. Commonly used human commercial media were investigated for culturing animal PSCs. These findings suggest that this simple and standardized methodology may be applicable in several fields such as the study of the pharmacological effects of drugs on the haematopoietic line and the study of new strategies in cellular therapy for some human diseases.

Creatinine concentration in plasma from dog, rat, and mouse: a comparison of 3 different methods

BACKGROUND

There are numerous methods for analyzing creatinine concentration in plasma, including the Jaffé alkaline picrate method in various modifications, enzymatic tests, and chromatographic methods.

OBJECTIVE

The purpose of this study was to evaluate whether an enzymatic method could replace a Jaffé method for routine creatinine measurements in plasma from dogs, rats, and mice. The enzymatic method and a compensated Jaffé method were tested against a high-pressure liquid chromatography (HPLC) method, regarded as the gold standard for creatinine measurement.

METHODS

Heparinized plasma samples were obtained from 20 beagle dogs, 20 Wistar rats, and 20 CD1-strain mice. The 2 test kits (Roche Diagnostics), Creatinine Jaffé Compensated and the enzymatic Creatinine Plus Version 2 reagent, were used on a Cobas Integra 400. The Jaffé compensated method used a calibration adjustment of 18 micromol/L to correct for the protein matrix in serum and plasma. The HPLC method was an isocratic method using a weak cation-exchange column following protein precipitation.

RESULTS

Creatinine concentrations obtained using the enzymatic and the Jaffé methods differed significantly from the results obtained by the HPLC method. For dog plasma, mean values of 61.2, 61.8, and 67.8 micromol/L were obtained by the compensated Jaffé, enzymatic and HPLC methods, respectively. In the rat, respective mean values were 26.7, 21.9, and 23.0 micromol/L, and in the mouse, respective mean values were 14.2, 5.4, and 9.2 micromol/L.

CONCLUSION

The enzymatic method can replace the Jaffé method for plasma creatinine determination in dogs, rats, and mice because results from the enzymatic method were closer to HPLC values than were those of the Jaffé method.

Bacteriocidal activity of lizard and mouse serum for Borrelia lonestari, putative agent of a Lyme-like illness (AKA STARI or Masters disease) in Missouri

OBJECTIVE

To determine responses of Borrelia lonestari and Borrelia burgdorferi to Eastern Fence lizard (Sceloporus undulatus) and Swiss-Webster mouse (Mus musculus) sera.

RESULTS

Lizard sera lysed both Borrelia lonestari and Borrelia burgdorferi. Mouse sera lysed only Borrelia lonestari.

CONCLUSIONS

Borrelia lonestari and Borrelia burgdorferi spirochetes did not survive exposure to lizard sera. Mice are reservoirs for Borrelia burgdorferi but may not be a Borrelia lonestari reservoir because spirochetes did not survive exposure to mouse sera.

Ultrasensitive detection of domoic acid in mouse blood by competitive ELISA using blood collection cards

Domoic acid (DA), an analog of the excitatory amino acid glutamate, is produced by the diatom genus Pseudo-nitzschia and acts as a neurotoxin in humans. During diatom blooms, DA can contaminate shellfish, as well as other filter feeding organisms, and can be transferred by ingestion to higher trophic levels, including marine mammals and humans. The prevalence of this algal toxin and its effects on protected species makes measurement of domoic acid in living animals a necessary biomonitoring tool for the near future. Blood collection cards have already been used for the sampling, extraction and detection of brevetoxin in blood from exposed laboratory animals and, more recently, marine mammals. However, a difficulty unique to measuring DA in blood is the rapid rate (>95% in 2h) at which it is cleared from blood. To meet this challenge, a direct competitive ELISA (cELISA), a method of detection with extremely high sensitivity and specificity, was used to analyze the blood of DA-exposed mice after extraction from the blood collection cards. More than 99% of DA was cleared from blood within 4h post dosage; however, domoic acid was still quantifiable (>0.7ngml(-1)) at 4h from blood spot extracts and still detectable at 24h when compared to control blood spots. By using this highly sensitive assay in conjunction with the use of blood spot cards for easy blood sample extraction, this method could be a very effective means of biomonitoring domoic acid in marine mammals in the field, as well as human populations.

Thermal acclimation and seasonal variations of erythrocyte size in the Andean mouse Phyllotis xanthopygus rupestris

Seasonal hematological adjustments in small mammals may include changes in the number and size of the red cells or changes in other linked blood parameters. The direction and magnitude of these changes vary in different species. We hypothesized that the observed variations of the red cell adjustments could be directly related to the magnitude of the seasonal temperature differential, and predicted that the annual red cell size variation in rodents from environments with marked seasonal changes would tend to disappear, if the animals were raised under milder and constant environments. To test this idea, we got field blood samples from the Andean species Phyllotis xanthopygus rupestris enduring a winter-summer thermal differential of at least 20 degrees C. These animals had significantly smaller erythrocytes during the winter. Contrary to our prediction, their offspring born and raised under constant temperature conditions showed a similar trend. Unless the effective environmental cue differed from the one we used, these results favor the idea of a genetically determined annual red cell size variation that occurs independent of thermal acclimation and acclimatization.

Investigation of a new input function validation approach for dynamic mouse microPET studies

PURPOSE

Image-derived input functions are desirable for quantifying biological functions in dynamic mouse micro positron emission tomography (PET) studies, but the input function so derived needs to be validated. Conventional validation using serial blood samples is difficult in mice. We introduced the theoretical basis and used computer simulations to show the capability of a new approach that requires only a small number of blood samples per mouse but uses multiple animals.

PROCEDURES

2-Deoxy-2-[(18)F]fluoro-D-glucose (FDG) kinetics (60 minutes) were simulated for 10 to 20 animals with three to six blood samples available per animal. Various amounts/types of noise/errors in the blood measurements were assumed, and different amounts/types of errors were added to the true input function to simulate image-derived input function. Deviations between blood samples and the derived input function were examined by statistical techniques to evaluate the capability of the approach for detecting the simulated errors in the derived input function.

RESULTS

For a total of 60 blood samples and a 10% measurement noise, a 5% contaminating error in image-derived input function can be detected with a statistical power of approximately 0.9 and with a 95% confidence. The power of the approach is directly related to the error magnitude in the image-derived input function, and is related to the total number of blood samples taken, but is inversely related to the measurement noise of the blood samples.

CONCLUSION

The new validation approach is expected to be useful for validating input functions derived with image-based methods in dynamic mouse microPET studies.

Comparative analysis of normal prion protein expression on human, rodent, and ruminant blood cells by using a panel of prion antibodies

BACKGROUND

It is not known whether variant CJD can be transmitted within the human population by blood transfusion. The expression of normal cellular prion protein (PrPC) by different blood cell types may permit selective uptake and dissemination of infectivity.

STUDY DESIGN AND METHODS

The normal distribution of PrPC on the major blood cell types of species known to be susceptible to natural or experimental transmissible spongiform encephalopathies was studied. Blood from healthy humans, mice, hamsters, cattle, and sheep was examined by flow cytometry by using a large panel of antibodies with different prion protein (PrP) epitope specificities to maximize the detection of PrP variants across species and cell type.

RESULTS

PrP was detected on all major human blood cells types except eosinophils, but was not detected as ubiquitously or uniformly on major blood cell types of different animal species.

CONCLUSION

Different animal species have unique patterns of expression of PrPC on blood cell types, with none equivalent to the human pattern. This needs to be considered when extrapolating from animal models of blood-borne transmissible spongiform encephalopathy infectivity, particularly in regard to the risk assessment of potential variant CJD spread within the human population. The relationship between PrP distribution and infectivity distribution in blood needs further investigation.

Of mice and men: comparison of the ultrastructure of megakaryocytes and platelets

OBJECTIVE

Mice provide an excellent model for studying platelet and megakaryocyte (Mk) biology in vivo. Given the increasing use of transgenic and knockout mice, it is important that any similarities and differences between murine and human platelet/Mk biology be well defined. Therefore the objective of this study was to compare and contrast in detail any significant morphological differences between Mks, platelets, and mechanisms of thrombopoiesis in humans and mice.

METHODS

The distinctive structural and ultrastructural features of murine and human platelets and Mks are reviewed. Several platelet and Mk glycoproteins were also localized in murine cells by immunoelectron microscopy using polyclonal antibodies directed against human platelet proteins and compared to existing human data. Finally, the ultrastructure of maturing murine and human Mks in culture and bone marrow were examined in detail to facilitate a comparison of either in vivo or in vitro platelet production.

RESULTS

Human and murine platelets exhibit significant but well-established morphological differences. Murine platelets are smaller and more numerous and display much greater granule heterogeneity than their human counterparts. Immunoelectron microscopy also demonstrated that murine platelet alpha-granules are highly compartmentalized. In fact, they are remarkably similar to human alpha-granules, with asymmetrical distribution of von Willebrand factor (vWF), and labeling of alpha(IIb)beta(3) and P-selectin (CD62P) in the granule limiting membrane. In vivo, murine but not human Mks are also consistently localized within the spleen. Subcellular events accompanying platelet formation and release by murine Mks are presented for the first time, and compared to human. Consistent differences were found in the pathway of redistribution of demarcation membranes preceding platelet formation, which may be important for the clarification of the mechanism of platelet release.

CONCLUSION

Human and murine platelets and Mks display several characteristic ultrastructural differences (size, number, histological distribution, platelet shedding) which have been emphasized and analyzed in this report. Nevertheless, since there are also many close similarities (organelle and glycoprotein subcellular distribution) mice offer an excellent in vivo model to study various aspects of human Mk and platelet biology.

Assessment of rapid remobilization intervals with G-CSF and SCF in murine and rhesus macaque models

BACKGROUND

Defining the optimum regimen and time for repeat peripheral blood progenitor cell mobilization would have important clinical applications.

STUDY DESIGN AND METHODS

Remobilization with SCF and G-CSF at 2 weeks after an initial mobilization in mice and at 2 or 4 weeks after an initial mobilization in nonhuman primates was examined. In mice, competitive repopulation assays were used to measure long-term progenitor cell-repopulating activity. In monkeys, mobilization of hematopoietic progenitor CFUs was used as a surrogate marker for progenitor cell-repopulating ability.

RESULTS

Efficacy of progenitor cell remobilization differed in the two animal species. In mice, peripheral blood progenitor cell-repopulating ability with repeat mobilization at 2 weeks was 70 percent of that with the initial mobilization. In monkeys, there was no significant difference in peripheral blood progenitor cell mobilization between the initial and the repeat mobilizations at 2 weeks. In mobilizations separated by 4 weeks, however, peripheral blood progenitor cell mobilization was higher than that with initial mobilizations.

CONCLUSION

In animal models, mobilization of peripheral blood progenitor cells with remobilization after a 2-week interval is similar to or moderately decreased from that with the initial mobilization. Progenitor cell collection at this time point may be useful in certain clinical circumstances. A 4-week interval between remobilizations may be preferable. Clinical trials in humans would be useful to clarify these issues.

Dynamic changes in mouse lipoproteins induced by transiently expressed human phospholipid transfer protein (PLTP): importance of PLTP in prebeta-HDL generation

The plasma phospholipid transfer protein (PLTP) plays an important role in the regulation of plasma high density lipoprotein (HDL) levels and governs the distribution of HDL sub-populations. In the present study, adenovirus mediated overexpression of human PLTP in mice was employed to investigate the distribution of PLTP in serum and its effect on plasma lipoproteins. Gel filtration experiments showed that the distributions of PLTP activity and mass in serum are different, suggesting that human PLTP circulated in mouse plasma as two distinct forms, one with high and the other with low specific activity. Our study further demonstrates that overexpression of PLTP leads to depletion of HDL and that, as PLTP activity declines, replenishment of the HDL fraction occurs. During this process, the lipoprotein profile displays transient particle populations, including apoA-IV and apoE-rich particles in the LDL size range and small particles containing apoA-II only. The possible role of these particles in HDL reassembly is discussed. The increased PLTP activity enhanced the ability of mouse sera to produce pre(beta)-HDL. The present results provide novel evidence that PLTP is an important regulator of HDL metabolism and plays a central role in the reverse cholesterol transport (RCT) process.

Morphological and haematological parameters in the Algerian mouse (Mus spretus) inhabiting an area contaminated with heavy metals

In the present study morphological (ratio of body weight to body length, weight of internal organs) and haematological parameters (cells count, haemoglobin concentration, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration) were used for monitoring potential effects of metal contaminants on the Algerian mouse (Mus spretus). The study also provided the opportunity to evaluate the use of morphological and haematological characteristics as indicators of a metal stress. Data were taken from a riverside population inhabiting a heavy metal-contaminated site and compared with those collected from a reference population of the same species. With the exception of non-reproductive males, all mice weighed less in the metal-polluted site as compared to the reference site. Spleen and kidney masses were also less in contaminated mice but mean haemoglobin concentration was greater in the polluted group versus controls. Responses of mice from the polluted area may indicate physiological stress due to diminished environmental quality. Results also suggest that M. spretus may be used as an indicator in pollution monitoring.

Structure and function of murine alphaIIbbeta3 (GPIIb/IIIa): studies using monoclonal antibodies and beta3-null mice,

The alphaIIbeta3 receptor (GPIIb/IIIa) is the only platelet-specific integrin receptor and the most abundant adhesion/aggregation receptor on the surface of human platelets. Since mice are increasingly being used as models of human disease, we analyzed the structure and function of murine platelet alphaIIbeta3, utilizing both beta3 integrin-deficient mice, who have a phenotype that resembles Glanzmann thrombasthenia, and our hamster monoclonal antibody (mAb) 1B5 to murine alphaIIbbeta3. By immunoblot analysis, flow cytometry, and mAb binding studies, mouse platelets express abundant amounts of alphaIIbbeta3 (60-80,000 copies/platelet). Like their human counterparts, murine alphaIIb and beta3 exhibit different electrophoretic motilities under nonreducing (aIIb 135k Da; beta3 92k Da) and reducing (aIIb 120k Da; beta3 108k Da) conditions, and the alphaIIbbeta3 complex is dissociated by EDTA at pH 8 and 37 degrees C. Murine beta3 is less susceptible to proteolysis by plasmin than is human beta3. In addition to defective platelet aggregation, mouse platelets lacking alphaIIbbeta3 and alphaVbeta3 are unable to adhere to fibrinogen and prothrombin, but retain the ability to adhere to fibronectin and collagen. Following platelet activation, beta3-null platelets express slightly less P-selectin than do wild-type mouse platelets. Moreover, beta3-null platelets have altered tyrosine phosphorylation patterns following thrombin- and collagen-induced aggregation. These results suggest fundamental similarities between human and mouse platelet activation and aggregation, but delineate subtle differences that need to be considered when comparing studies from mice and humans.

Lead effects on offspring depend on when mouse mothers were exposed to lead

Target mice were nursed by mothers given lead starting (1) when target mice were born; (2) after conception of target mice, or (3) during the mothers' own pre-weaning age. These target mice are called, respectively, POSTNATAL, GESTATIONAL, and PRE-MATING. Compared to developments in control mice, postnatal lead slowed brain weight development, lowered asymptotic brain weight, decreased DNA per brain somewhat, but had no effect on protein per brain. Gestational lead similarly slowed brain weight development, lowered asymptotic brain weight, greatly decreased DNA per brain, but had no effect on protein per brain. In contrast, pre-mating lead significantly increased brain weight and protein per brain and lowered DNA per brain substantially. These effects of pre-mating lead on brain weight and protein per brain could be due to the effects of lead on developing maternal reproductive systems or to lead's presence during the rarely studied ovulation-to-fertilization period.

Guinea pig serum erythropoietin (EPO) selectively stimulates guinea pig erythroid progenitors: human or mouse erythroid progenitors do not form erythroid burst-forming unit colonies in response to guinea pig serum EPO

Erythropoietin (EPO) is the primary regulator of mammalian erythropoiesis, providing a proliferative and differentiative signal to the early EPO-responsive erythroid progenitors, burst-forming unit-erythroid (BFU-E) and colony-forming unit-erythroid, as well as to later EPO-responsive erythroid progenitors. EPO is secreted by the kidney in response to hypoxia and anemia. There is an extensive biological crossreactivity between human EPO and the EPOs of other mammals. Necas et al. have reported that this crossreactivity may not include the guinea pig (Cavia porcelllus). Because the specificity of the guinea pig's erythropoietic responses may be of biological significance, we compared guinea pig hypoxic serum with mouse (m) and human (h) recombinant (r) EPOs for their ability to induce erythroid progenitor proliferation and differentiation in semisolid cultures. Guinea pig bone marrow mononuclear cells (BMMCs) formed BFU-E colonies in response to guinea pig hypoxic serum, rhEPO, or rmEPO in a dose-dependent fashion. Neither human nor mouse BMMCs responded to guinea pig hypoxic serum; however, guinea pig hypoxic serum exerted no inhibitory effect on human or mouse in vitro erythroid differentiation in the presence of rhEPO or rmEPO. The intensity of the EPO band on Western blotting analysis of guinea pig hypoxic serum was significantly greater than in nonhypoxic serum. This suggests that guinea pig erythropoiesis is mediated by EPO and stimulated by hypoxia in a fashion similar to that observed in human and mouse erythropoiesis. Furthermore, guinea pig EPO did not stimulate human or mouse erythroid differentiation in vitro, whereas guinea pig erythroid progenitors could be stimulated by human or mouse EPO, suggesting structural differences in guinea pig EPO and EPO receptor (EPOR) compared with human or mouse EPO and EPOR. These differences probably evolved after the guinea pig's ancestors diverged from myomorph rodents. Further characterization of the guinea pig EPO and EPOR should facilitate our understanding of the interaction between EPO and EPOR.

Stress affects corticosteroid and immunoglobulin concentrations in male house mice (Mus musculus) and prairie voles (Microtus ochrogaster)

Glucocorticoids, secreted in response to perceived stress, can suppress immunoglobulin (Ig) levels and compromise immune function in mice and rats. Prairie voles (Microtus ochrogaster) have been reported to exhibit basal corticosterone concentrations that would cause pathological changes in the immune function of most other rodents. The goals of the present study were to verify that serum corticosterone concentrations are high in prairie voles, as compared with house mice (Mus musculus), by measuring serum corticosterone with the same RIA; to examine the effects of mild stressors on corticosterone response in both species and to examine the effects of elevated corticosterone levels on IgM and IgG levels in prairie voles and house mice. After 2 weeks of randomly timed 15-min daily restraint or cold-water swim sessions, animals were injected with sheep red blood cells. The data confirmed that basal blood concentrations of corticosterone were higher in prairie voles than house mice, but these high levels doubled after the first swim session in prairie voles, indicating that the adrenals can respond to stressors by producing increased corticosterone. After stress, antibody production (both IgM and IgG) was reduced in house mice but not in prairie voles, despite higher blood concentrations of glucocorticoids in prairie voles. Although body mass was statistically equivalent between species, prairie voles and mice differed dramatically in adrenal and splenic masses. Average adrenal mass of prairie voles was approximately three times the average mass of these organs in house mice; in contrast, the average splenic mass of house mice was approximately three times that of prairie voles. These data may be relevant to seasonal changes in immune function and survival.

A comparison of murine and human factor XI

Factor XI is a plasma glycoprotein that is required for contact activation initiated fibrin formation in vitro and for normal hemostasis in vivo. In preparation for developing a mouse model of factor XI deficiency to facilitate investigations into this protease's contributions to coagulation, we cloned the complementary DNA for murine factor XI, expressed the protein in a mammalian expression system, and compared its properties with human recombinant factor XI. The 2.8-kb murine cDNA codes for a protein of 624 amino acids with 78% homology to human factor XI. Both recombinant murine and human factor XI are 160 kD homodimers comprised of two 80 kD polypeptides connected by disulfide bonds. Murine factor XI shortens the clotting time of human factor XI deficient plasma in an activated partial thromboplastin time assay, with a specific activity 50% to 70% that of the human protein. In a purified system, murine factor XI is activated by human factor XIIa and thrombin in the presence of dextran sulfate. Murine factor XI differs from human factor XI in that it undergoes autoactivation slowly in the presence of dextran sulfate. This is due primarily to murine factor XIa preferentially cleaving a site on zymogen factor XI within the light chain, rather than the activation site between Arg371 and Val372. Northern blots of polyadenylated messenger RNA show that murine factor XI message is expressed, as expected, primarily in the liver. In contrast, messenger RNA for human factor XI was identified in liver, pancreas, and kidney. The studies show that murine and human factor XI have similar structural and enzymatic properties. However, there may be variations in tissue specific expression and subtle differences in enzyme activity across species.

Purification and characterisation of the hexokinase of Plasmodium berghei, a murine malaria parasite

Hexokinase (EC 2.7.1.1) activity in cell-free Plasmodium berghei was 35 and 5 times higher as compared to normal and P. berghei-infected mouse erythrocytes, respectively. Maximal enzyme activity was present in the cytosolic fraction of the isolated parasite. Manifold purification of parasite hexokinase was achieved with Sephadex G-200. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed parasite enzyme subunit in the molecular weight range of 47 kDa with ATP (adenosine triphosphate) Km of 2 mM. Two out of three mice immunised with the hexokinase fraction were protected upon challenge with live parasites.

Cellular immunity is not compromised by high serum corticosterone concentrations in prairie voles

Glucocorticoids compromise immune function in glucocorticoid-sensitive species (e.g., mice), but these immunosuppressive effects may be reduced in glucocorticoid-resistant species. Prairie voles (microtus ochrogaster) have been characterized as glucocorticoid-resistant to their high circulating levels of corticosterone. Because glucocorticoid-sensitive species display suppressed lymphocyte proliferation in response to elevated blood glucocorticoid levels, proliferative values were hypothesized to be reduced in house mice (Mus musculus) compared with prairie voles. Prairie voles exhibited significantly higher splenocyte proliferative responses to the T cell mitogen, Concanavalin A, despite having higher basal total and free serum corticosterone levels than mice. Neither total nor free serum corticosterone correlated with proliferative responses from either species. These data provide further evidence for glucocorticoid resistance in prairie voles and suggest that the interactions between the hypothalamic-pituitary-adrenal axis and the immune system in prairie voles may differ from those in mice or other glucocorticoid-sensitive species. Therefore, prairie voles may serve as a valuable animal model for the syndrome of glucocorticoid resistance in humans and the role of glucocorticoids in conditions characterized by a hyperactive immune system.

Role of vitamin D3-binding protein in activation of mouse macrophages

When mouse peritoneal nonadherent (lymphocytes) cells were treated with lysophosphatidylcholine (lyso-Pc) and cultured with adherent cells (macrophages) in 1% fetal calf serum (FCS)- or adult mouse serum (AMS)-supplemented medium for 3 h, markedly enhanced phagocytic and superoxide-generating capacities of macrophages were observed. Stepwise cultivation of lyso-Pc-treated B cells and untreated T cells with an FCS-supplemented medium generated a macrophage-activating factor (MAF), whereas cultivation of lyso-Pc-treated B cells alone in AMS-supplemented medium was sufficient to generate the MAF. The accumulated evidence suggests that lyso-Pc-inducible beta-galactosidase of B lymphocytes and the Neu-1 sialidase of T lymphocytes modified the bovine serum vitamin D3-binding protein (DBP) to yield the MAF, a protein with N-acetylgalactosamine as the remaining sugar. In contrast, the lyso-Pc-inducible beta-galactosidase of B cells alone modified mouse DBP to yield the MAF. These observations led us to conclude that bovine DBP carries a trisaccharide composed of N-acetylgalactosamine, galactose, and sialic acid, whereas mouse DBP carries a disaccharide composed of N-acetylgalactosamine and galactose. Thus, macrophages of a T-cell-deficient nude (BALB/c nu/nu) mouse and a T-cell Neu-1 sialidase-deficient SM/J mouse were efficiently activated by administration of lyso-Pc.