Variation at the apolipoprotein (apo) AI-CIII-AIV gene cluster and apo B gene loci is associated with lipoprotein and apolipoprotein levels in Italian children.

We have used RFLPs of the apolipoprotein (apo) B gene and apo AI-CIII-AIV gene cluster to estimate the genetic contribution of variation at these loci to the variability of plasmid lipid, lipoprotein, and apolipoprotein levels in 209 children from Sezze in central Italy. The sample was randomly divided into group I (107 children) and group II (102 children). Four site polymorphisms (PvuII, XbaI, MspI, and EcoRI) of the apo B gene and five site polymorphisms (XmnI, PstI, SstI, PvuII-CIII, and PvuII-AIV) of the apo AI-CIII-AIV gene cluster were examined in group I children. After adjustment for gender, age, and body-mass index, polymorphisms at both gene loci (PvuII-B, PvuII-CIII, and PvuII-AIV) were associated with significant effects on the levels of plasma apo AI, apo B, or high-density lipoprotein-cholesterol. RFLPs that showed significant effects in group I were genotyped in group II. All three polymorphisms were associated with similar effects on apolipoprotein levels, though for all RFLPs the magnitude of the effects was smaller in the group II children and only statistically significant for the effect of the PvuII-B genotype on apo AI levels. In the total sample of 209 children 7.4% of the sample variance in apo AI levels was explained by variation associated with the apo B PvuII-B RFLP. In addition, the PvuII-B RFLP was associated with significant effects on plasma apo B levels and explained 5.7% of the sample variance. The PvuII-CIII and PvuII-AIV polymorphisms were both associated with differences in apo AI levels, explaining 3.7%-5.7% of the sample variance. Taken together, the three PvuII polymorphisms explained 17.7% of the phenotypic variance in apo AI levels. There was significant evidence for an effect of nonlinearity of the PvuII-CIII genotypes on apo AI levels, with the individuals heterozygous for the polymorphism having the highest apo AI levels. No evidence of interaction between genotype and gender, age, and body-mass index was shown by covariance analysis. The molecular explanation of this effect is unclear. Our data show that variation at both the apo AI-CIII-AIV and apo B loci are associated with lipoprotein and apolipoprotein levels in this sample of Italian children.     

Effects of the apolipoprotein(a) size polymorphism on the lipoprotein(a) concentration in 7 ethnic groups

Summary Apolipoprotein(a) [apo(a)] exhibits a genetic size polymorphism explaining about 40% of the variability in lipoprotein(a) [Lp(a)] concentration in Tyroleans. Lp(a) concentrations and apo(a) phenotypes were determined in 7 ethnic groups (Tyrolean, Icelandic, Hungarian, Malay, Chinese, Indian, Black Sudanese) and the effects of the apo(a) size polymorphism on Lp(a) levels were estimated in each group. Average Lp(a) concentrations were highly significantly different among these populations, with the Chinese (7.0mg/dl) having the lowest and the Sudanese (46mg/dl) the highest levels. Apo(a) phenotype and derived apo(a) allele frequencies were also significantly different among the populations. Apo(a) isoform effects on Lp(a) levels were not significantly different among populations. Lp(a) levels were however roughly twice as high in the same phenotypes in the Indians, and several times as high in the Sudanese, compared with Caucasians. The size variation of apo(a) explains from 0.77 (Malays) to only 0.19 (Sudanese) of the total variability in Lp(a) levels. Together these data show (I) that there is considerable heterogeneity of the Lp(a) polymorphism among populations, (II) that differences in apo(a) allele frequencies alone do not explain the differences in Lp(a) levels among populations and (III) that in some populations, e.g. Sudanese Blacks, Lp(a) levels are mainly determined by factors that are different from the apo(a) size polymorphism.     

Nonsynonymous polymorphic sites in the apolipoprotein (apo) A-IV gene are associated with changes in the concentration of apo B- and apo A-I-containing lipoproteins in a normal population.

The aims of this study were to detect polymorphic sites in the apolipoprotein (apo) A-IV gene, to establish their frequencies, to determine potential haplotypes, and to investigate the role of these polymorphisms in lipid metabolism. A sequencing study of four individuals led to the identification of two synonymous mutations (codons 9 and 54) and three nonsynonymous mutations (Val-8----Met, Gln360----His, and Thr347----Ser) and of a VNTR polymorphism within a series of three or four CTGT repeats in the noncoding region of exon 3. Frequencies of these polymorphisms were determined in 291 students by using naturally occurring (BstEII for the synonymous mutation in codon 54, HinfI for Thr347----Ser, and Fnu4HI for Gln360----His) or artificially introduced restriction-enzyme cutting sites (BstEII for the synonymous mutation in codon 9 and MamI for Val-8----Met), subsequent to PCR amplification. The four-base deletion/insertion polymorphism and its localization cis or trans to the mutations in codons 347 and 360 were studied by direct sequencing of PCR-amplified DNA from 87 students. Frequencies of the rarer alleles were .007 for apo A-IV-8:Met, .04 for the synonymous mutation in codon 9, .14 for the synonymous mutation in codon 54, .16 for apo A-IV347:Ser, .07 for apo A-IV360:His, and .39 for the four-base of insertion. Apo A-IV360:His in all cases was cis-localized to the (CTGT)3 repeat and apo A-IV347:Thr; and apo A-IV347:Ser was cis-localized to the (CTGT)4 repeat and apo A-IV360:Gln. Four haplotypes formed from these three polymorphic sites were thus found. The apo A-IV347:Ser allele was associated both with significantly lower plasma apo B concentrations in both sexes and with significantly lower LDL-cholesterol concentrations in men. Heterozygous carriers of apo A-IV360:His exhibited significantly higher concentrations of LDL-cholesterol and lower Lp(a) concentrations, compared with apo A-IV360:Gln homozygotes. We could not confirm the previously reported association of apo A-IV360:His with elevated HDL-cholesterol concentrations. In the population, the Val-8----Met polymorphism was not associated with significantly different lipid concentrations, but in a family study the Met-8 allele was associated with lower HDL-cholesterol and higher LDL-cholesterol concentrations. In conclusion, our results indicate an important role of the apo A-IV gene locus in the metabolism of apo B and, to a lesser extent, apo A-I containing lipoproteins.     

Measurement of lipoprotein lipase and hepatic triacylglycerol lipase in post-heparin plasma of the cynomolgus monkey

Conditions for measurement of the lipolytic activities, lipoprotein lipase and hepatic triacylglycerol lipase in cynomolgus monkey postheparin plasma are described. The two activities are separable by heparin-Sepharose chromatography. Goat anti-human hepatic triacylglycerol lipase serum inhibits monkey hepatic triacylglycerol lipase activity and allows direct measurement of lipoprotein lipase in post-heparin plasma. While both human and homologous serum can be used as a source of activator apolipoprotein, homologous serum produces a much greater activation.     

Serum insulin concentration and arginine tolerance test in the cynomolgus monkey (Macaca fascicularis)

The standard value of serum insulin was determined to be less than 75 microU/ml with ninety-eight female adult cynomolgus monkeys of wild origin. Then, fifteen apparently healthy laboratory-bred female cynomolgus monkeys aged 6-8 years were studied to know the usefulness of the arginine tolerance test (ATT) by measuring blood glucose, insulin and glucagon. Prior to ATT, all animals had been diagnosed as non-diabetic by the intravenous glucose tolerance test (IVGTT). Arginine hydrochloride was infused intravenously at a dose of 0.5 g/kg. BW under anesthesia. According to the standard value of insulin, fifteen animals were divided into two groups, that is, the low (n = 7) and the high (n = 8) value groups. In the low value group, glucose and insulin value did not change significantly after arginine infusion and their responses were similar to those in the control group (saline infused, n = 4). But glucagon markedly increased from 10 to 45 minutes post infusion. In the high value group, glucagon response was similar to that in the low value group, while glucose and insulin values significantly decreased. It is concluded that the pancreatic alpha-cell function (glucagon secretion) can be judged by the ATT in the cynomolgus monkey but the beta-cell function (insulin secretion) can not be diagnosed.     

Amastin mRNA abundance in Trypanosoma cruzi is controlled by a 3'-untranslated region position-dependent cis-element and an untranslated region-binding protein

The genome of Trypanosoma cruzi contains tandem arrays of alternating genes encoding amastin and tuzin. Amastin is a surface glycoprotein abundantly expressed on the intracellular mammalian amastigote form of the protozoan parasite, and tuzin is a G-like protein. We demonstrated previously that the amastin-tuzin gene cluster is polycistronically transcribed to an equal extent in all parasite life cycle stages. The steady state level of amastin mRNA, however, is 68-fold more abundant in amastigotes than in epimastigotes. Here we show that the half-life of amastin mRNA is 7 times longer in amastigotes than in epimastigotes. Linker replacement experiments demonstrate that the middle one-third of the 630-nucleotide 3'-untranslated region (UTR) is responsible for the amastin mRNA up-regulation. This positive effect is dependent on the distance of the 3'-UTR segment from the stop codon and the polyadenylation site as well as on its orientation. A protein or protein complex more abundant in amastigotes than in epimastigotes binds to this minimally defined 3'-UTR segment and may be involved in its regulatory function.     

The cynomolgus monkey (Macaca fascicularis) is the best animal model for the study of steroid glucuronidation

Intense research efforts performed during the past decade clearly established the major role of glucuronidation and uridine-diphospho-glucuronosyltransferase (UGT) enzymes for steroid metabolism in humans. However, a clear understanding of the physiological importance of this metabolic process requires in vivo studies. Numerous evidences ascertain that simians are the most appropriate animal models for such studies. Indeed human and monkey have a similar pattern of steroidogenesis, unlike common laboratory mammals such as rat or mouse. Furthermore, human and monkey are unique in having high levels of circulating androsterone glucuronide and androstane-3-diol glucuronide (3-Diol-G). In addition, characterization of eight monkey UGT proteins demonstrated the similarity of their conjugation activity toward steroid hormones. Like human ones, monkey enzymes are expressed in steroid target tissues, where they preferentially glucuronidate androgen and estrogen metabolites. In monkey tissues, immunohistochemical studies demonstrated that UGT2B proteins are expressed in a cell-type specific manner in ovary and kidney, where they control androgens and aldosterone inactivation. These results identify the cynomolgus monkey as an appropriate animal model for the determination of cellular localization of UGT enzymes in steroid target tissues and for the identification of endogenous or exogenous stimuli affecting steroid glucuronidation.     

The relationship among apolipoprotein(a) polymorphisms, the low-density lipoprotein receptor-related protein, and the very low density lipoprotein receptor genes, and plasma lipoprotein(A) concentration in the Czech population

Increased plasma concentration of lipoprotein(a) [Lp(a)] is an established independent risk factor for coronary artery disease (CAD), which is strongly genetically determined. This study was designed to investigate the relationship between the K-IV and (TTTTA)n apolipoprotein(a) [apo(a), protein; APOA, gene] polymorphisms, as well as the C766T low-density lipoprotein receptor-related protein (LRP) and the (CGG)n very low density lipoprotein receptor (VLDLR) polymorphisms on the one hand, and plasma Lp(a) levels in Czech subjects who underwent coronary angiography on the other hand. The lengths of the alleles of the APOA K-IV and (TTTTA)n polymorphisms were strongly inversely correlated with plasma Lp(a) levels in univariate analysis (r = -0.41, p < 10(-4) and r = -0.20, p < 0.01, respectively). Multivariate analysis revealed significant associations between the APOA polymorphisms studied and plasma Lp(a) levels in subjects expressing only one APOA K-IV allele (p < 10(-6) for K-IV and p < 0.001 for TTTTA). In subjects expressing both APOA K-IV alleles, the multivariate analysis revealed that only the APOA K-IV alleles were inversely correlated with plasma Lp(a) levels (p < 0.001). Associations between both the LRP and VLDLR gene polymorphisms and plasma Lp(a) levels were only of borderline significance (p < 0.06 and p < 0.07, respectively) and were not confirmed in multivariate analysis. In conclusion, both APOA length polymorphisms significantly influenced plasma Lp(a) concentration in the Czech population studied, and this circumstance could explain the association in this population observed earlier between APOA (TTTTA)n polymorphism and CAD (Benes et al. 2000). Only a minor role in the regulation of plasma Lp(a) levels is suggested for the C766T LRP and the (CGG)n VLDLR polymorphisms.     

Zinc deficiency decreases plasma level and hepatic mRNA abundance of apolipoprotein A-I in rats and hamsters

The influence of Zn deficiency on the plasma level as well asthe hepatic and intestinal gene expression of apolipoprotein (apo) A-Iwas examined in rats and hamsters. Male Sprague-Dawley rats (8 wk old)and Golden Syrian hamsters (7 wk old) were assigned to three dietarytreatments: Zn adequate (ZA, 30 mg Zn/kg diet), Zn deficient (ZD,<0.5 mg Zn/kg diet), and Zn replete (ZDA, ZD animals fed the ZA dietfor the last 2 days). The dietary treatments lasted for 18 days forrats or 6 wk for hamsters. For the measurement of apoA-I mRNAabundance, hamster apoA-I cDNA was cloned from the small intestine. Thefull-length 905-base pair cDNA shared ~80% similarity with thehuman, rat, and mouse apoA-I cDNAs. Hepatic and plasma Zn levels werereduced in ZD animals but normalized in ZDA rats and increased in ZDAhamsters compared with ZA animals. Zn deficiency reduced plasma apoA-Iand hepatic apoA-I mRNA levels 13 and 38%, respectively, in ZD rats.The 2 days of Zn replenishment raised plasma apoA-I and hepatic apoA-ImRNA levels in ZDA rats by 34 and 28%, respectively, higher than ZArats. Similarly, these levels were decreased by 18 and 25%,respectively, in ZD hamsters but normalized in ZDA hamsters comparedwith ZA hamsters. In contrast to the alterations of hepatic apoA-I mRNAlevels, neither Zn deficiency nor subsequent Zn repletion producedalterations in the intestinal apoA-I mRNA abundance. Data from thisstudy demonstrated that Zn deficiency specifically decreases hepaticapoA-I gene expression, which may at least be partly responsible forthe reduction of plasma apoA-I levels.

     

Novel hyperprolactinemia and hyperprolactinemic anovulation model using the cynomolgus monkey (Macaca fascicularis)

We investigated the relationship between the menstrual cycle and hormone levels in cynomolgus monkeys, and developed a sulpiride-induced hyperprolactinemic anovulation model. On this study, we demonstrated the usefulness of the commercial human prolactin immunoradiometric assay kit for the measurement of cynomolgus monkey serum samples. In the normal menstrual cycle of the cynomolgus monkey, serum prolactin concentrations were not significantly different between luteal and follicular phases. However, the serum prolactin concentration tended to elevate at the ovulation stage. And serum progesterone began to increase after an estradiol surge, and then declined before the ensuing preovulatory rise in estradiol. During the luteal phase, the serum concentration of progesterone was elevated. Moreover, we aimed to develop an anovulation model, using sulpiride-induced hyperprolactinemia in the cynomolgus monkey. The serum prolactin level gradually increased during the twice-daily administration of sulpiride, and the drug produced as big a response at 5 mg/kg. In this study, the length of the menstrual cycle was approximately 29 days in normal cynomolgus monkeys. When treatment with sulpiride had been continued for more than one month, serum progesterone and estradiol levels fell to within the range seen in the follicular phase of the normal cycle, and the absence of ovulation was recognized by laparoscopy. Moreover, in this period we found that amenorrhea or anovulatory menstruation in the experimental animals. We could produce an anovulatory model induced by sulpiride repeatedly administered over a long time period. Our findings suggest that the cynomolgus monkey is useful as a endocrinological model that uses prolactin as a parameter and as an anovulatory model; thus, it could be a useful model for the hyperprolactinemic amenorrhea and/or anovulation seen in humans.     

The cynomolgus monkey (Macaca fascicularis) is the best animal model for the study of steroid glucuronidation

Intense research efforts performed during the past decade clearly established the major role of glucuronidation and uridine-diphospho-glucuronosyltransferase (UGT) enzymes for steroid metabolism in humans. However, a clear understanding of the physiological importance of this metabolic process requires in vivo studies. Numerous evidences ascertain that simians are the most appropriate animal models for such studies. Indeed human and monkey have a similar pattern of steroidogenesis, unlike common laboratory mammals such as rat or mouse. Furthermore, human and monkey are unique in having high levels of circulating androsterone glucuronide and androstane-3α-diol glucuronide (3α-Diol-G). In addition, characterization of eight monkey UGT proteins demonstrated the similarity of their conjugation activity toward steroid hormones. Like human ones, monkey enzymes are expressed in steroid target tissues, where they preferentially glucuronidate androgen and estrogen metabolites. In monkey tissues, immunohistochemical studies demonstrated that UGT2B proteins are expressed in a cell-type specific manner in ovary and kidney, where they control androgens and aldosterone inactivation. These results identify the cynomolgus monkey as an appropriate animal model for the determination of cellular localization of UGT enzymes in steroid target tissues and for the identification of endogenous or exogenous stimuli affecting steroid glucuronidation.     

The linkage with apolipoprotein (a) in lipoprotein (a) modifies the immunochemical and functional properties of apolipoprotein B

Lipoprotein (a) [Lp(a)] was isolated from several donors and its apolipoprotein (a) [apo(a)] dissociated by a reductive treatment, generating the apo(a)-free form of Lp(a) [Lp(a--)] that contains apolipoprotein B (apo B) as its sole protein. Using anti-apo B monoclonal antibodies, the properties of apo B in Lp(a), Lp(a--), and autologous low-density lipoprotein (LDL) were compared. Marked differences in apo B immunoreactivity were found between these lipoproteins, due to the presence of apo(a) in Lp(a). Apo(a) enhanced the expression of two epitopes in the amino-terminal part of apo B while it diminished the immunoreactivity of three other epitopes in the LDL receptor binding domain. Accordingly, the binding of the lipoproteins to the LDL receptor was also decreased in the presence of apo(a). In a different experimental system, the incubation of antibodies that react with 27 distinct epitopes distributed along the whole length of apo B sequence with plastic-bound Lp(a) and Lp(a--) failed to reveal any epitope of apo B that is sterically hindered by the presence of apo(a). Our results demonstrate that the presence of apo(a) modified the organization and function of apo B in Lp(a) particles. The data presented indicate that most likely the modification is not due to a steric hindrance but that some more profound conformational changes are involved. We suggest that the formation of the disulfide bridge between apo B and apo(a) in Lp(a) alters the system of disulfide bonds present in apo B and thereby modifies apo B structure.     

Acute toxicology and pharmacokinetic assessment of a ribozyme (ANGIOZYME) targeting vascular endothelial growth factor receptor mRNA in the cynomolgus monkey

The potential acute toxicity of a ribozyme (ANGIOZYME) targeting the flt-1 vascular endothelial growth factor (VEGF) receptor mRNA was evaluated in cynomolgus monkeys following i.v. infusion or s.c. injection. ANGIOZYME was administered as a 4-hour i.v. infusion at doses of 10, 30, or 100 mg/kg or a s.c. bolus at 100 mg/kg. End points included blood pressure, electrocardiogram (ECG), clinical chemistry, hematology, complement factors, coagulation parameters, and ribozyme plasma concentrations. ANGIOZYME was well tolerated, with no drug-associated morbidity or mortality. There was no clear evidence of ANGIOZYME-related adverse effects in this study. Slight increases in spleen weight and lymphoid hyperplasia were observed in several animals. However, these changes were not dose dependent. Steady-state concentrations of ANGIOZYME were achieved during the 4-hour infusion of 10, 30, or 100 mg/kg. Dose-dependent elimination of ANGIOZYME was observed, with faster clearance at the two highest doses. ANGIOZYME was slowly absorbed after s.c. administration, resulting in steady-state concentrations for the 9-hour sampling period. Monkeys in this toxicology study received significant plasma ANGIOZYME exposure by both the s.c. and i.v. routes.     

Patterns of association between genetic variability in apolipoprotein (apo) B, apo AI-CIII-AIV, and cholesterol ester transfer protein gene regions and quantitative variation in lipid and lipoprotein traits: influence of gender and exogenous hormones.

Patterns of RFLP association were studied, to identify gene regions influencing quantitative variation in lipid and lipoprotein traits (coronary artery disease [CAD] risk factors or metabolically related traits). Subjects (118 female and 229 male; age 20-59 years) were selected for health. Multiple RFLPs were used to sample variability in regions around genes for apolipoprotein (apo) B (restriction enzymes HincII, PvuII, EcoRI, and XbaI), apo AI-CIII-AIV (BamHI, XmnI, TaqI, PstI, SstI, and PvuII) and cholesterol ester transfer protein (TaqI). Separate analyses were done by gender. The sample was truncated at mean +/- 4 SD, to remove extreme outliers. There was no significant gender difference in RFLP genotype frequency distribution. After trait-level adjustment to maximize removal of concomitant variability, analysis of variance was used to estimate the percentage trait phenotypic variance explained by measured variability in the gene regions studied. Fewer gene regions were involved in men, with less influence on quantitative trait variation than in women, in whom hormone use affected association patterns. Gender differences imply that pooling genders or adjusting data for gender effects removes genetic information and should be avoided. The association patterns show that variability around the candidate genes modulates trait levels: the genes are contributors to the genetics of CAD risk variables in a healthy sample.     

Intracytoplasmic injection of frozen-thawed epididymal spermatozoa in a nonhuman primate model,the cynomolgus monkey (Macaca fascicularis)

Intracytoplasmic sperm injection (ICSI) with frozen-thawed epididymal spermatozoa was performed in the cynomolgus monkey (Macacafascicularis) to produce embryos in vitro. Eleven sexually mature females were hyperstimulated with an GnRH agonist (1.8 mg active triptorelin per 2 kg body weight), followed (2 weeks later) by rFSH (37.5 IU per 2 kg daily) for 12 days, and finally 1000 IU of hCG. Epididymal spermatozoa were collected from a single adult male monkey. The first stimulation cycle resulted in 90 oocytes; 70% of which were metaphase II (MII). Sixty-four percent of these MII oocytes were fertilized. Comparing ovarian response of five monkeys that underwent a second stimulation cycle there was an increase in oocyte quantity (13.2 versus 9.2 oocytes per monkey) but the percentage of MII oocytes remained the same at 58%. Fertilization and cleavage rates were also reduced but there was an increase in the number of embryos available for transfer. Overall, four monkeys became pregnant resulting in the birth of two healthy infants and two abortions. These findings show that ovarian stimulation by GnRH-rFSH did not compromise the developmental competence of the oocytes; effective combination of cryopreservation of epididymal spermatozoa and ICSI is possible in nonhuman primate reproduction, and thus has potential application in the conservation of highly endangered nonhuman primate species, and the cynomolgus monkey is a reliable biomedical research model to study the potential risks and benefits associated with assisted reproductive techniques prior to approval for clinical trials on humans.     

The effect of apolipoprotein(a)-, apolipoprotein E-, and apolipoprotein A4- polymorphisms on quantitative lipoprotein(a) concentrations.

The effects of apolipoprotein (a), apolipoprotein-E, and apolipoprotein-A4 isoforms on quantitative lipoprotein(a) [Lp(a)] levels were assessed in a sample of 142 Dutch families consisting of two parents and their adolescent twin offspring. A total heritability of 95% was estimated for plasma Lp(a) concentrations. The largest part of this heritability was due to the apo(a) locus which explained 61% of the total variance in Lp(a) levels. The pattern of familial correlations for the residual part of the Lp(a) variance that could not be attributed to the apo(a) isoforms, suggested genetic influences on the residual variance. We addressed the question whether this residual genetic variance could be ascribed to the apoE or the apoA4 locus. A simultaneous analysis of all three loci showed that both the apoE and the apoA4 polymorphism did not contribute significantly to Lp(a) variation.