The pharmacokinetics and metabolism of diclofenac in chimeric humanized and murinized FRG mice

The pharmacokinetics of diclofenac were investigated following single oral doses of 10 mg/kg to chimeric liver humanized and murinized FRG and C57BL/6 mice. In addition, the metabolism and excretion were investigated in chimeric liver humanized and murinized FRG mice. Diclofenac reached maximum blood concentrations of 2.43 ± 0.9 µg/mL (n = 3) at 0.25 h post-dose with an AUC_inf of 3.67 µg h/mL and an effective half-life of 0.86 h (n = 2). In the murinized animals, maximum blood concentrations were determined as 3.86 ± 2.31 µg/mL at 0.25 h post-dose with an AUC_inf of 4.94 ± 2.93 µg h/mL and a half-life of 0.52 ± 0.03 h (n = 3). In C57BL/6J mice, mean peak blood concentrations of 2.31 ± 0.53 µg/mL were seen 0.25 h post-dose with a mean AUC_inf of 2.10 ± 0.49 µg h/mL and a half-life of 0.51 ± 0.49 h (n = 3). Analysis of blood indicated only trace quantities of drug-related material in chimeric humanized and murinized FRG mice. Metabolic profiling of urine, bile and faecal extracts revealed a complex pattern of metabolites for both humanized and murinized animals with, in addition to unchanged parent drug, a variety of hydroxylated and conjugated metabolites detected. The profiles in humanized mice were different to those of both murinized and wild-type animals, e.g., a higher proportion of the dose was detected in the form of acyl glucuronide metabolites and much reduced amounts as taurine conjugates. Comparison of the metabolic profiles obtained from the present study with previously published data from C57BL/6J mice and humans revealed a greater, though not complete, match between chimeric humanized mice and humans, such that the liver humanized FRG model may represent a model for assessing the biotransformation of such compounds in humans.

Identification of Metabolism and Excretion Differences of Procymidone between Rats and Humans Using Chimeric Mice: Implications for Differential Developmental Toxicity

A metabolite of procymidone, hydroxylated-PCM, causes rat-specific developmental toxicity due to higher exposure to it in rats than in rabbits or monkeys. When procymidone was administered to chimeric mice with rat or human hepatocytes, the plasma level of hydroxylated-PCM was higher than that of procymidone in rat chimeric mice, and the metabolic profile of procymidone in intact rats was well reproduced in rat chimeric mice. In human chimeric mice, the plasma level of hydroxylated-PCM was less, resulting in a much lower exposure. The main excretion route of hydroxylated-PCM-glucuronide was bile (the point that hydroxylated-PCM enters the enterohepatic circulation) in rat chimeric mice, and urine in human chimeric mice. These data suggest that humans, in contrast to rats, extensively form the glucuronide and excrete it in urine, as do rabbits and monkeys. Overall, procymidone's potential for causing teratogenicity in humans must be low compared to that in rats.

Different rates of telomere attrition in peripheral lymphocytes in a pair of dizygotic twins with hematopoietic chimerism

Hematopoietic chimerism in dizygotic twins is due to placental vascular anastomoses and arises when hematopoietic stem cells from one twin home to the bone marrow of the other. We report a case of hematopoietic chimerism in a pair of 27-year-old dizygotic twins who each had a mixture of 46,XX and 46,XY blood lymphocytes, both with 98% male (XY) lymphocytes and 2% female (XX) lymphocytes. Analysis of telomere length by T/C FISH revealed that the female twin generally had longer telomeres than the male twin. Moreover, in the male sibling, the telomeres within the female lymphocytes were shortened to 87% of their original length, while the telomeres within the male lymphocytes were 33% longer in the female sibling. Thus, telomere length attrition in peripheral lymphocytes is determined mainly by the environment of the cell and less by intracellular factors.

Genotype-specific environmental impact on the variance of blood values in inbred and F1 hybrid mice

Mice are important models for biomedical research because of the possibility of standardizing genetic background and environmental conditions, which both affect phenotypic variability. Inbred mouse strains as well as F1 hybrid mice are routinely used as genetically defined animal models; however, only a few studies investigated the variance of phenotypic parameters in inbred versus F1 hybrid mice and the potential interference of the genetic background with different housing conditions. Thus, we analyzed the ranges of clinical chemical and hematologic parameters in C3H and C57BL/6 inbred mice and their reciprocal F1 hybrids (B6C3F1, C3B6F1) in two different mouse facilities. Two thirds of the blood parameters examined in the same strain differed between the facilities for both the inbred strains and the F1 hybrid lines. The relation of the values between inbred and F1 hybrid mice was also affected by the facility. The variance of blood parameters in F1 hybrid mice compared with their parental inbred strains was inconsistent in one facility but generally smaller in the other facility. A subsequent study of F1 hybrid animals derived from the parental strains C3H and BALB/c, which was done in the latter housing unit, detected no general difference in the variance of blood parameters between F1 hybrid and inbred mice. Our study clearly demonstrates the possibility of major interactions between genotype and environment regarding the variance of clinical chemical and hematologic parameters.

Lack of evidence for leukocyte maternal microchimerism in primary biliary cirrhosis

AIM: It is reasonable to assume that microchimerism could also be involved in the induction of primary biliary cirrhosis (PBC). However, previous reports investigated only fetus-microchimerism in women patients. Maternal microchimerism has not been investigated until now. The current study aimed to clear either maternal microchimerism was involved in the pathogenesis of PBC or not.

METHODS: We used fluorescence in situ hybridization on paraffin-embedded tissue (We called “Tissue-FISH”.) to determine whether maternal cells infiltrated in male patients who were diagnosed as having PBC. Tissue-FISH was performed by using both X and Y specific probes on the biopsy liver sample of 3 male PBC patients.

RESULTS: Infiltrating lymphocytes demonstrated both X and Y signals in all 3 male patients.

CONCLUSION: Maternal microchimerism dose not play a significant role in PBC. PBC may not relate to fetus and maternal microchimerism.

Heterologous immunity: an overlooked barrier to tolerance

In less than 50 years the field of organ transplantation has transitioned from an experimental concept to clinical commonplace. Notwithstanding the dramatic improvements in patient and allograft outcomes, chronic rejection and the complications from life-long immunosuppressive therapy remain significant problems. The induction of transplantation tolerance, indefinite allograft acceptance independent of chronic immunosuppressive therapy, remains the ultimate objective in transplantation. Many strategies have achieved tolerance to transplanted tissue in rodents; however, few, if any, have shown equal efficacy when tested in non-human primate transplant models or human patients. A critical distinction between specific pathogen-free mice and primates or human patients is the exposure of the latter to environmental pathogens and the resultant-acquired immune history. Recent data has shown that virally induced, alloreactive immune responses can provide a potent barrier to tolerance. In this review, we discuss one of the most robust methods for tolerance, the induction of hematopoietic chimerism as well as the influence of viral infections on the alloimmune response.

Age dependent changes in plasma anti-Müllerian hormone concentrations in the bovine male, female, and freemartin from birth to puberty: relationship between testosterone production and influence on sex differentiation

To understand the behaviour of the gonads, in terms of hormonal secretion, in a model of intersexual development naturally occurring in mammals, we determined plasma concentrations of testosterone, progesterone, and anti-Müllerian hormone (AMH) in bovine freemartins, and compared them to normal levels measured in males and females from birth to puberty. We found that newborn males and freemartins have very high concentrations of AMH (over 700ng/ml). Conversely, plasma AMH concentration is always below 120ng/ml in females. While values remain stable in males for the first five months of life, they sharply decrease in the freemartins within the first fortnight, and reach female levels, which demonstrates that AMH is essentially originated in the male twin. In young bulls the trend of plasma testosterone concentrations is opposite to that of the AMH. The rise in testosterone production at puberty corresponds to a sharp decline in AMH concentrations. Bovine plasma concentrations of AMH are surprisingly higher than those measured in other mammals, including man and mouse. The results obtained are discussed in reference to comparative aspects of endocrine functions.

Non-invasive determination of the paternal HLA haplotype of a fetus using kinetic PCR to detect fetal microchimerism in maternal plasma

Knowledge of fetal HLA type can be important if cord blood (CB) is being considered as a stem cell source for transplantation. The feasibility of determining the paternally inherited HLA haplotype of a fetus was explored through analysis of fetal DNA in the maternal circulation. A 5-year-old child with relapsed acute leukemia was a candidate for transplantation. The HLA type of the fetal sibling was needed to assist with evaluation of this potential cord blood donor. DNA was isolated from maternal plasma and whole blood. Kinetic PCR using sequence-specific primers for paternal HLA-A, -B, and -DRB1 alleles was performed. Alleles corresponding to one paternal haplotype were detectable in plasma, but not in whole blood. Alleles from the alternative haplotype were not detectable. This demonstrated that the fetus shared at least one haplotype with the patient and therefore arrangements were made to bank the CB. The maternal haplotype of the fetus could not be determined in the presence of maternal DNA. The prenatal fetal typing was confirmed by typing the newborn's CB. This rapid non-invasive technique may facilitate the selection of CB units for banking based on needed HLA types.

Physiological migration of hematopoietic stem and progenitor cells

Hematopoietic stem cells (HSCs) reside predominantly in bone marrow, but low numbers of HSCs are also found in peripheral blood. We examined the fate of blood-borne HSCs using genetically marked parabiotic mice, which are surgically conjoined and share a common circulation. Parabionts rapidly established stable, functional cross engraftment of partner-derived HSCs and maintained partner-derived hematopoiesis after surgical separation. Determination of the residence time of injected blood-borne progenitor cells suggests that circulating HSCs/progenitors are cleared quickly from the blood. These data demonstrate that HSCs rapidly and constitutively migrate through the blood and play a physiological role in, at least, the functional reengraftment of unconditioned bone marrow.

Genomic analysis of clinical samples with serologic ABO blood grouping discrepancies: identification of 15 novel A and B subgroup alleles

Since the cloning in 1990 of complementary DNA corresponding to messenger RNA transcribed at the blood group ABO locus, polymorphisms and phenotype-genotype correlations have been reported by several investigators. Exons 6 and 7, constituting 77% of the gene, have been analyzed previously in samples with variant phenotypes but for many subgroups the molecular basis remains unknown. This study analyzed 324 blood samples involved in ABO grouping discrepancies and determined their ABO genotype. Samples from individuals found to have known subgroup alleles (n = 53), acquired ABO phenotypes associated with different medical conditions (n = 65), probable chimerism (n = 3), and common red blood cell phenotypes (n = 109) were evaluated by ABO genotype screening only. Other samples (n = 94) from apparently healthy donors with weak expression of A or B antigens were considered potential subgroup samples without known molecular background. The full coding region (exons 1-7) and 2 proposed regulatory regions of the ABO gene were sequenced in selected A (n = 22) or B (n = 12) subgroup samples. Fifteen novel ABO subgroup alleles were identified, 2 of which are the first examples of mutations outside exon 7 associated with weak subgroups. Each allele was characterized by a missense or nonsense mutation for which screening by allele-specific primer polymerase chain reaction was performed. The novel mutations were encountered in 28 of the remaining 60 A and B subgroup samples but not among normal donors. As a result of this study, the number of definable alleles associated with weak ABO subgroups has increased from the 14 previously published to 29.

Blood fetal microchimerism in primary biliary cirrhosis

The autoimmune nature of primary biliary cirrhosis (PBC) is well established. We tested the hypothesis that fetal microchimerism indicated by the persistence of circulating fetal cells in women years after pregnancy might contribute to the aetiopathogenesis of PBC through a graft-versus-host-like response. We extracted DNA from the peripheral blood cells of 36 women carefully selected from 173 consecutive PBC patients, who were matched with 36 healthy women by age, age of last son, and number of children. Both patients and controls had to have male offspring, and no history of miscarriages or blood transfusions; they could not be twins. We tested all of the samples for the presence of two specific Y-chromosome sequences (SY154 and SRY) by amplifying DNA in a nested polymerase chain reaction. Y-chromosome-specific DNA was detected in the peripheral blood cell DNA of 13 (36%) of the 36 women with PBC and in 11 (31%) of the 36 healthy controls. The two groups of PBC patients with and without male DNA sequences were similar in terms of their clinical, biochemical, and serological features. Y-chromosome sequences were found in three of the four PBC women with associated systemic sclerosis. All of the 24 Y-positive samples contained SY154 sequences, but only three PBC patients and six controls showed the presence of both SY154 and SRY sequences. This discrepancy may suggest that not only fetal cells but also fragments of fetal DNA are present in maternal circulation. Overall, our data do not support the hypothesis that fetal microchimerism plays a significant role in the onset or progression of PBC.