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Biomedical subjects

Y Obara

Publications and source records attributed to Y Obara.

At least 19 recordsLinked to original sources

Interaction of GH polymorphism with body weight and endocrine functions in Japanese black calves.

We assessed the interaction of GH gene polymorphisms (AA, AB and BB genotypes) with body weight and measures of endocrine function in Japanese black calves at 10 months of age. The average body weight for the BB genotype (281+/-5 kg) was significantly lower (P=0.0017, ANOVA) than those for the AA (324+/-9 kg) and AB (317+/-7 kg) genotypes. Plasma concentrations of insulin and IGF-I were greater for the AA genotype than for the AB genotype, and AB and BB genotypes, respectively. There were significant differences in the triglyceride and cholesterol concentrations among the GH genotypes. The area under the basal GH concentration was significantly greater (P=0.0314) for the AA genotype than for the two other genotypes. The incremental area over the basal GH concentrations in response to intravenous GHRH injection (0.4 microg/kg BW) was significantly smaller (P=0.0005) for the BB genotype than for the two other genotypes. In addition, linear regression analysis between GH incremental area induced by GHRH and body weight demonstrated that there was a positive linear correlation (r=0.6496, P<0.002) for incremental areas less than 600 ng min/ml, but a negative correlation (r=0.6473, P<0.05) for incremental areas over 600 ng min/ml. These findings indicate that the GH genotypes of the animals could be associated with difference in the GH response in Japanese black cattle at 10 months of age. We also observed a relationship between genotype and animal performances, but other studies on more animals in different conditions must be realized to make a definite conclusion.

Animals↗

Isolation and characterization of sex chromosome rearrangements generating male muscle dystrophy and female abnormal oogenesis in the silkworm, Bombyx mori.

In deletion-mapping of W-specific RAPD (W-RAPD) markers and putative female determinant gene (Fem), we used X-ray irradiation to break the translocation-carrying W chromosome (W( Ze )). We succeeded in obtaining a fragment of the W( Ze ) chromosome designated as Ze (W), having 3 of 12 W-RAPD markers (W-Bonsai, W-Yukemuri-S, W-Yukemuri-L). Inheritance of the Ze (W) fragment by males indicates that it does not include the Fem gene. On the basis of these results, we determined the relative positions of W-Yukemuri-S and W-Yukemuri-L, and we narrowed down the region where Fem gene is located. In addition to the Ze (W) fragment, the Z chromosome was also broken into a large fragment (Z(1)) having the +( sch ) (1-21.5) and a small fragment (Z(2)) having the +( od ) (1-49.6). Moreover, a new chromosomal fragment (Ze (W)Z(2)) was generated by a fusion event between the Ze (W) and the Z(2) fragments. We analyzed the genetic behavior of the Z(1) fragment and the Ze (W)Z(2) fragment during male (Z/Z(1) Ze (W)Z(2)) and female (Z(1) Ze (W)Z(2)/W) meiosis using phenotypic markers. It was observed that the Z(1) fragment and the Z or the W chromosomes separate without fail. On the other hand, non-disjunction between the Ze (W)Z(2) fragment and the Z chromosome and also between the Ze (W)Z(2) fragment and the W chromosome occurred. Furthermore, the females (2A: Z/Ze (W)Z(2)/W) and males (2A: Z/Z(1)) resulting from non-disjunction between the Ze (W)Z(2) fragment and the W chromosome had phenotypic defects: namely, females exhibited abnormal oogenesis and males were flapless due to abnormal indirect flight muscle structure. These results suggest that Z(2) region of the Z chromosome contains dose-sensitive gene(s), which are involved in oogenesis and indirect flight muscle development.

Animals↗

Postprandial changes in plasma concentrations of growth hormone and ghrelin around weaning in the goat.

We measured and compared plasma levels of GH and ghrelin in response to feeding in 4-week-old (milk replacer-fed) and 13-week-old (alfalfa hay cube-fed) goats, in order to elucidate whether or not the postprandial regulation of these hormone levels changes around weaning. Furthermore, we examined the effects of suckling from the dam or intravenous glucose administration on both hormone and insulin levels in kids. In 4-week-old goats, feeding of a milk replacer diet significantly increased plasma GH levels without changing level of ghrelin. In contrast, in 13-week-old goats, feeding of hay cubes did not change the levels of either ghrelin or GH. Suckling of milk directly from the dams significantly increased the levels of GH and insulin, but not ghrelin, in kids. Finally, intravenous injection of glucose (0.625 mmol/kg BW) did not cause any significant increase in the levels of GH or ghrelin, despite a significant increase in the levels of insulin and glucose. From these results, we conclude that the regulatory system of the somatotropic axis is altered by weaning or weaning-associated processes, and that ghrelin levels may not be involved in this alteration in young goats.

Animals↗

Molecular cytogenetic characterization and chromosomal distribution of the satellite DNA in the genome of Oxya hyla intricata (Orthoptera: Catantopidae).

The genomic DNA of the grasshopper (Oxya hyla intricata) was subjected to electrophoresis after digestion with HaeIII, and the result showed two bands of highly repetitive DNA, approximately 200 and 400 bp in length. The 200-bp HaeIII-digested fragment was cloned and characterized by sequencing and fluorescence in situ hybridization (FISH). The results showed the presence of two distinct satellite DNA (stDNA) families: one consisting of a 169-bp repeated element having an A+T content of 60.9% and the other consisting of a 204-bp repeated element having an A+T content of 53.9%. No significant homology between the two stDNA families was observed. FISH showed that the chromosomal locations of these families are different from each other. The 169-bp element was located in the C-band-positive regions of the short arms of most of the chromosomes, whereas the 204-bp element was located in the centromeric regions of three chromosome pairs. These results imply that the origins of these two DNA families are different. The results of zoo-blot hybridization to the genomic DNA from four Oxya species, O. hyla intricata, O. japonica japonica, O. chinensis formosana, and O. yezoensis, suggest that the two stDNA families found in the present study are species-specific for O. hyla intricata.

Animals↗

Developmental changes in the kinetics of glucose and urea in Holstein calves.

Because weaning is the point when the nutrient composition of feed changes for the neonatal ruminant, the present experiment was conducted to assess the developmental changes in the kinetics of glucose and urea over this period, using stable isotopes of glucose and urea, at 4, 13, and 24 wk in calves. Plasma concentrations of nonesterified fatty acids, amino-N, urea-N, and insulin-like growth factor-I increased, but that of growth hormone decreased with age. The plasma glucose concentration increased at 13 wk of age and thereafter decreased at 24 wk of age. The glucose irreversible loss and recycling rates were significantly higher at 4 wk of age than at 13 and 24 wk of age. On the other hand, the irreversible loss and recycling rates of urea, as well as the urea pool size, were higher at 24 wk of age than at 4 and 13 wk. It is concluded that weaning at 6 wk is the pivotal time for the alteration of glucose kinetics. However, the aging process, but not weaning, is important for changes in the kinetics of urea in calves.

Aging↗

Suppressing actions of butyrate on growth hormone (GH) secretion induced by GH-releasing hormone in rat anterior pituitary cells.

We assessed the inhibitory effects of butyrate on the growth hormone (GH) secretion in order to investigate the cellular mechanisms in rat somatotrophs. Isolated anterior pituitary cells were cultured in DMEM for several hours, either in the presence (1, 3, or 10mM) or absence of butyrate, and then stimulated with 10(-7)M GHRH for 30 min, in the presence of butyrate at the concentrations used for the previous culture. The increase in GHRH-induced GH release was significantly reduced in a time-dependent and concentration-dependent manner in the cells previously cultured with butyrate. GH content (the sum of GH released into the medium induced by GHRH stimulation and the GH remaining in the cells after stimulation) was reduced by the culture of cells in the presence of butyrate, which was also inversely dependent on the concentrations used for the culture. Simultaneous addition of an L-type Ca(2+) channel blocker, nifedipine (10 pM), to the medium during 10(-9)M GHRH stimulation significantly reduced the stimulated GH release, which was further significantly decreased by a simultaneous addition of 10 mM butyrate. Butyrate blunted the GHRH (10(-9)M)-induced increase in cellular cyclic AMP and calcium ion concentrations, the activity of protein kinases (A and C), and GHmRNA expression. The expression of mRNA for GPR 41 and 43, known as receptors for short-chain fatty acids, was confirmed in the anterior pituitary cells. These findings suggest that butyrate inhibits GHRH-induced GH release as well as GH production, and the cellular inhibitory actions of butyrate occur in diverse cellular signaling pathways of rat somatotrophs.

Animals↗

Characterization of SSU and LSU rRNA genes of three Trypanosoma (Herpetosoma) grosi isolates maintained in Mongolian jirds.

Trypanosoma (Herpetosoma) grosi, which naturally parasitizes Apodemus spp., can experimentally infect Mongolian jirds (Meriones unguiculatus). Three isolates from A. agrarius, A. peninsulae, and A. speciosus (named SESUJI, HANTO, and AKHA isolates, respectively) of different geographical origin (AKHA from Japan, and the others from Vladivostok), exhibited different durations of parasitaemia in laboratory jirds (2 weeks for HANTO, and 3 weeks for the others). To assess the genetic background of these T. grosi isolates, their small (SSU) and large subunit (LSU) ribosomal RNA genes (rDNA) were sequenced along with those of 2 other Herpetosoma species from squirrels. The SSU rDNA sequences of these 3 species along with available sequences of 3 other Herpetosoma trypanosomes (T. lewisi, T. musculi and T. microti) seemed to reflect well the phylogenetic relationship of their hosts. Three isolates of T. grosi exhibited base changes at 2-6 positions of 2019-base 18S rDNA, at 5-29 positions of 1817/1818-base 28Salpha rDNA, or 1-5 positions of 1557-1559-base 28Sbeta rDNA, and none was separated from the other 2 isolates by rDNA nucleotide sequences. Since base changes of Herpetosoma trypanosomes at the level of inter- and intra-species might occur frequently in specified rDNA regions, the molecular analysis on these regions of rodent trypanosomes could help species/strain differentiation and systematic revision of Herpetosoma trypanosome species, which must be more abundant than presently known.

Animals↗

Deep lamellar keratoplasty by deep parenchyma detachment from the corneal limbs.

AIM: To improve the deep lamellar keratoplasty technique. METHOD: For the easy and reliable perfomance of deep lamellar keratoplasty (DLKP), detachment of Descemet's membrane through the corneal limber flap was improved. To expose Descemet's membrane, the parenchyma was detached by hydrodelamination through a sclerocorneal flap made in the corneal limbs. The parenchyma was removed after the pseudochamber between it and Descemet's membrane was maintained with viscoelastic material. The corneal graft was placed with a running suture. 22 eyes were treated. RESULTS: Complete exposure of Descemet's membrane was obtained in 20 of the 22 eyes (91%). The membrane was perforated in five of the 22 eyes (23%) during surgery, and two of the 22 eyes (9%) were converted to penetrating keratoplasty. These two eyes developed keratoconus after acute corneal hydrops. CONCLUSION: Compared with the conventional procedure, this new method provides easy, reliable exposure of Descemet's membrane.

Adult↗

Karyotypic evolution and organization of the highly repetitive DNA sequences in the Japanese shrew-moles, Dymecodon pilirostris and Urotrichus talpoides.

The karyological relationship and organization of highly repetitive DNA sequences in Japanese shrew-moles were studied by zoo-blot hybridization and fluorescence in situ hybridization (FISH). When the genomic DNA of the eastern race of Urotrichus talpoides was digested with PstI, three fragments of highly repetitive DNA sequences, approximately 0.7, 0.9, and 1.4 kb in length, were observed as distinct bands. The results of FISH in the eastern race of U. talpoides using these three fragments separately as probes showed that the 0.7-kb PstI fragment was distributed in the centromeric regions of most chromosomes, and that the 0.9- and 1.4-kb fragments were predominantly located in the C-heterochromatin region of chromosome 13p. Although the western race of U. talpoides also had three PstI fragments, 0.9- and 1.4-kb PstI fragments were more ambiguous than those of the eastern race. The PstI- digested genomic DNA in Dymecodonpilirostris produced only a faint 0.9-kb band, and its signal patterns obtained by zoo-blot hybridization were clearly different from those of U. talpoides. The 0.7-kb fragment of U. talpoides hybridized strongly with the 0.9-kb fragment of D. pilirostris. In a FISH analysis, the 0.9-kb fragment of D. pilirostris hybridized with highly repetitive DNA in the centromeric regions of most chromosomes from both D. pilirostris and U. talpoides. Zoo-blot hybridization and FISH analyses suggest that the 0.9- and 1.4-kb PstI fragments were generated specifically in the genome of U. talpoides after the common ancestor differentiated into two extant shrew-mole species. A difference in the length of the centromeric elements between U. talpoides and D. pilirostris might be observed due to certain modifications of the repeating unit.

Animals↗

Effects of 5'-uridylic acid feeding on postprandial plasma concentrations of GH, insulin and metabolites in young calves.

Postprandial changes in plasma concentrations of GH, insulin, IGF-I, leptin and metabolites were compared between young Holstein bull calves fed with milk alone (control group) and with milk+5'-uridylic acid (UMP) (UMP group). UMP (2 g/day) was given with milk at 0830 h and 1530 h for 11 days from the 4th to the 14th day after birth. The perirenal fat weight was significantly lower in the UMP group than in the control group, but there was no significant difference in the weights of the liver, spleen and heart between the groups. Basal GH concentrations in the UMP group were slightly higher, but the postprandial increase in plasma insulin level and the area under the curve for insulin in the UMP group were significantly lower than those in the control group. There was no significant difference in IGF-I levels between the groups. In addition, the postprandial glucose concentrations were lower in the UMP group as reflected by the insulin level, and nonesterified fatty acid concentrations were not different. In the muscle (M. longissimus thoracis) sampled at 14 days of age, the triacylglycerol (TAG) content was significantly greater but glycogen content was significantly lower in the UMP group than in the control group. From these results, we have concluded that feeding 5'-UMP at 2 g/day for 11 days significantly alters TAG accumulation in the body and plasma concentrations of GH and insulin in young bull calves.

Animals↗

Responses induced by arginine-vasopressin injection in the plasma concentrations of adrenocorticotropic hormone, cortisol, growth hormone and metabolites around weaning time in goats.

In order to assess the biological significance of weaning and water deprivation on the control of plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, growth hormone (GH) and metabolites in response to stimulation with arginine-vasopressin (AVP) and corticotropin-releasing hormone (CRH), we carried out three experiments in which male goats before and after weaning were intravenously injected with AVP or CRH alone, or in combination with each other. In experiment 1, 17-week-old (post-weaning) goats were intravenously injected with AVP or CRH alone at the doses of 0.1, 0.3 and 1.0 nmol/kg body weight (BW). The AVP injection significantly and dose dependently increased plasma levels of ACTH, cortisol, GH and metabolites, whereas the injection with CRH did not cause significant increases in the levels of these parameters. In experiment 2, 4-week-old (pre-weaning) and 13-week-old (post-weaning) goats were injected with either AVP or CRH alone, followed by a combined injection of both secretagogues at a dose of 0.3 nmol/kg BW. Although the basal levels of the hormones and metabolites, with the exception of glucose, were greater in the 4-week-old goats, the hormone responses induced by stimulation with AVP were weaker than those induced in 13-week-old goats. Additionally, there were no responses in any hormone patterns to CRH stimulation in 4-week-old goats. In experiment 3, 13-week-old goats were injected with CRH alone followed by injection with AVP for two consecutive days of water deprivation. The animals were subjected to withdrawal of up to 20% of the total blood volume and water deprivation for up to 28 h. However, no significant differences in plasma ACTH, cortisol or GH levels were observed between days 1 and 2. Based on these results, we concluded that: (1) AVP is a more potent stimulant than CRH in terms of its ability to induce increases in plasma levels of ACTH, cortisol and GH; (2) the role of AVP as a secretagogue of hypothalamus-pituitary-adrenal hormones is strengthened, whereas the ineffective role of CRH remains unaltered, by weaning; (3) acute stress such as massive withdrawal of blood volume and subjection to water deprivation may not be sufficient burdens to alter stress-related hormone levels in young goats.

Adrenocorticotropic Hormone↗

Existence of GPR40 functioning in a human breast cancer cell line, MCF-7.

GPR40, which has recently been identified as a G-protein-coupled cell-surface receptor for long-chain fatty acids, was assessed in a human breast cancer cell line (MCF-7). We detected GPR40 mRNA by RT-PCR and found that oleate and linoleate, but not palmitate or stearate, caused an increase in cellular Ca(2+) concentrations, which was partially blocked by the pertussis toxin (PTX) treatment. We examined the expression of GPR40 mRNA by quantitative RT-PCR in the relation to cell number. It was significantly increased at the beginning and at the end of cell proliferation. These results indicate the possibility that GPR40 for long-chain fatty acids may be involved in cellular function such as cell proliferation, providing a new perspective for the action of long-chain fatty acids on mammary epithelial cells.

Breast Neoplasms↗

Suppressing effects of bisphenol A on the secretory function of ovine anterior pituitary cells.

We investigated the action of bisphenol A (BPA) on cellular GH release and content, cell number, GHmRNA expression, and concentrations of cellular cyclic AMP ([cAMP]c) and calcium ion ([Ca2+]c) in primary cultured ovine anterior pituitary cells. The following results were found: (1) BPA as well as nonylphenol (NP) at 10(-6) to 10(-3) M significantly and concentration-dependently suppressed basal and GHRH-stimulated GH release, and the cellular GH content, (2) BPA suppressed the cell number in a time- and concentration-dependent manner, (3) 10(-4)M BPA suppressed GHmRNA expression to 68% of control (BPA-free), and abolished GHRH (10(-8) M)-induced increases in [cAMP]c and [Ca2+]c. From these findings we conclude that BPA possesses a suppressing action on GH synthesis and release, and this suppressing action is probably related to impairment of cellular signal transduction systems in ovine anterior pituitary cells.

Animals↗

Rapid suppressing action of insulin-like growth factor-I (IGF-I) on GH release from anterior pituitary cells of goats.

Goat anterior pituitary cells were cultured to investigate the effects of insulin-like growth factor-I (IGF-I), insulin, and growth hormone (GH) on basal and GH-releasing hormone (GHRH)-induced GH release. Changes in cellular Ca2+ concentrations were also assessed to enable discussion of the cellular mechanisms of IGF-I. The cells were cultured for 48 h, and then stimulated with GHRH (10 nmol/l) for 30 min, with or without each test substance. In the control cells, IGF-I (10 and 100 ng/ml) significantly raised the basal, but did not change GHRH-induced GH release, resulting in the abolishment of GH release induced by GHRH in the presence of 100 ng/ml IGF-I. However, there was no significant effect of insulin (10, 100, and 1000 microU/ml) on basal and GHRH-induced GH release. In the cells cultured for 48 h with each test substance but stimulated for 30 min without the test substance, no significant change in the basal and GHRH-stimulated GH release was observed. Regardless of treatment, there was no significant effect on intra-cellular GH content. Analysis with a confocal laser microscope revealed that IGF-I (100 ng/ml) significantly increased the basal, but significantly reduced GHRH (10 nmol/l)-induced increase in cellular Ca2+ concentrations. From these findings we conclude that IGF-I exerts an acute suppressing action on the GHRH-induced GH release, which partly involves changes in cellular Ca2+ metabolism in goat somatotrophs.

Animals↗

Postprandial changes in plasma GH and insulin concentrations, and responses to stimulation with GH-releasing hormone (GHRH) and GHRP-6 in calves around weaning.

Changes in plasma concentrations of GH and insulin in response to feeding and stimulation with GH-releasing hormone (GHRH) or GH-releasing peptide (GHRP-6, a ligand for endogenous GH secretagogue receptors) were compared between 3-week-old (milk-fed) and 12-week-old (concentrate and hay-fed) calves. Feeding of a milk-replacer diet in 3-week-old animals significantly increased the basal (prefeeding) concentrations of GH, insulin and glucose in plasma, whereas feeding of concentrate and hay in 12-week-old animals did not cause a significant change in these traits. However, in the animals maintained on a milk-replacer diet until 12 weeks of age, postprandial plasma GH concentrations and AUC (area under the curve) were not different from those in the age-matched weaned group. The venous injection of either GHRH (0.25 microg/kg) or GHRP-6 (2.5 microg/kg) significantly increased plasma GH concentrations in both 3- and 12-week-old animals, but GH AUC was significantly greater in 3-week-old than in 12-week-old animals. Insulin concentration was transiently but significantly increased by the injection of GHRP-6 only in 12-week-old animals, the AUC being greater in 12-week-old than 3-week-old animals. From these results, we conclude that postprandial levels of plasma GH and insulin concentrations are altered after weaning and by aging, and that the quality of diets or development of the neuroendocrine functions in the digestive-pituitary system may be involved in this alteration.

Aging↗

Genetic correlation between serum insulin-like growth factor-1 concentration and performance and meat quality traits in Duroc pigs.

This study was intended to examine whether serum IGF-I concentration is appropriate for use as a physiological predictor for genetic improvement of meat production and meat quality traits in pigs. Heritabilities and genetic correlations were estimated for these traits. The Duroc breed used in this study was selected for seven generations for average daily BW gain (DG) from 30 to 105 kg of BW, loin-eye muscle area (EM), backfat thickness (BF), and intramuscular fat (IMF) content. Serum IGF-I concentration of boars and gilts at the fourth generation of selection and that of boars, gilts, and barrows from the fifth to seventh generations of selection were measured at 8 wk (IGFI-8W) for 832 animals and again at the time they reached 105 kg of BW (IGFI-105KG) for 834 animals. A multivariate REML procedure was used to estimate genetic parameters with a model incorporating generation of selection, sex, common environmental effect of litter, and individual additive genetic effects. Heritability estimates for IGFI-8W and IGFI-105KG were 0.23 +/- 0.02 and 0.26 +/- 0.03, respectively. The estimates of common environmental effect for IGFI-8W and IGFI-105KG were 0.20 +/- 0.02 and 0.03 +/- 0.01, respectively. Positive genetic correlations were estimated between IGFI-8W and DG (0.26 +/- 0.08), EM (0.22 +/- 0.10), and IMF (0.32 +/- 0.10). Moreover, the positive genetic correlation between IGFI-105KG and EM was 0.42 +/- 0.08. These results indicate that serum IGF-I concentration at an early stage of growth was effective for prediction of IMF, but it was not a reliable physiological predictor of genetic merit of meat production traits.

Adipose Tissue↗

Effects of long-chain fatty acids on cytosolic triacylglycerol accumulation and lipid droplet formation in primary cultured bovine mammary epithelial cells.

Mammary epithelial cells have recently been shown to express and secrete leptin into milk and to accumulate triacylglycerol (TAG) in cytosol. We examined the effects on the accumulation of cytosolic TAG of free fatty acid addition to the medium bathing bovine mammary epithelial cells (bMEC). Both saturated (palmitic and stearic) and unsaturated (oleic and linoleic) fatty acids stimulated the accumulation of TAG in a concentration-dependent manner from 50 to 400 microM and the expression of mRNA expression for CD36, which is involved in the uptake and secretion of long-chain fatty acids. However, leptin mRNA expression and lipid droplet formation were significantly increased only by the addition of unsaturated, but not saturated, fatty acids. Interestingly, both types of fatty acids stimulated alphas1-casein mRNA expression. These data suggest that the expression of leptin is related to droplet formation, whereas CD36 is related to cytosolic TAG accumulation, and that fatty acids or cytosolic TAG accumulation also have a role to accelerate differentiation of bMEC as shown by casein synthesis.

Animals↗

Effects of acetate and butyrate on the expression of leptin and short-form leptin receptor in bovine and rat anterior pituitary cells.

The effects of acetate and butyrate on leptin and leptin receptor (OB-R) expression in bovine and rat anterior pituitary were examined. In bovine tissues, leptin gene expression using RT-PCR was observed in fat and anterior pituitary but not in liver. Isolated anterior pituitary cells cultured in Dulbecco's modified Eagle's medium (DMEM) for 3 days were further cultured for 48 h in DMEM containing 10 mM acetate or butyrate or without any fatty acids as control. Western blot analysis revealed that the abundance of leptin protein was greater in the presence of acetate and butyrate than that for the control culture. Leptin abundance was increased in a dose- and time-dependent manner in bovine anterior pituitary cells. However, leptin expression in rat cells, of which the basal level was much greater than that in ovine cells, was significantly decreased by the culture with butyrate. In addition, we studied the effects of both fatty acids on OB-R mRNA expression using semi-quantitative RT-PCR. The results showed that butyrate significantly decreased the expression in both bovine and rat cells. These findings indicate that acetate and butyrate enhance leptin expression in bovine, but not in rat anterior pituitary cells while butyrate suppresses OB-Ra expression in both rat and bovine pituitaries.

Acetates↗