Different Weeks Of Age Research Articles

Comparative production performance and egg quality of Kuzi Ducks (Anas platyrhynchos) and its crosses with Khaki Campbell

Comparative performance of Kuzi ducks and its two crossbreds with Khaki Campbell, viz. Kuzi × Khaki Campbell (DK) and Khaki Campbell × Kuzi (KD) were carried out in respect to various production, egg weight, age at different production level and egg quality traits. The laying period body weight showed significant difference between the three genetic groups, irrespective the age of measurement and Kuzi duck recorded significantly higher body weight than the two crosses. The crossbreds attained 50% duck day production significantly earlier as compared to Kuzi. Egg production per bird and average duck day production % during different periods differed significantly and the crosses recorded higher egg production than the Kuzi. DK laid more than 300 eggs up to 72 weeks of age. The average duck day production % from 72 to 80 weeks of age in both the crosses were 80% or more, indicating that the crosses may be used for second cycle for egg production. Egg weight recorded at different weeks of age showed significant difference between genetic groups and the egg weight were higher in Kuzi than the crosses. As the age advanced, the egg weight increased. Egg quality traits measured at different weeks of age showed significant difference between genetic groups and within genetic groups at different ages for some traits. The egg quality decreased as the age advanced. The study indicated that the crosses of Kuzi and Khaki Campbell may be used for higher egg production with good quality eggs.

Characterization and Advancement of an Evaluation Method for the Treatment of Spontaneous Osteoarthritis in STR/ort Mice: GRGDS Peptides as a Potential Treatment for Osteoarthritis

STR/ort mice spontaneously exhibit the typical osteoarthritis (OA) phenotype. However, studies describing the relationship between cartilage histology, epiphyseal trabecular bone, and age are lacking. We aimed to evaluate the typical OA markers and quantify the subchondral bone trabecular parameters in STR/ort male mice at different weeks of age. We then developed an evaluation model for OA treatment. We graded the knee cartilage damage using the Osteoarthritis Research Society International (OARSI) score in STR/ort male mice with or without GRGDS treatment. We measured the levels of typical OA markers, including aggrecan fragments, matrix metallopeptidase-13 (MMP-13), collagen type X alpha 1 chain (COL10A1), and SRY-box transcription factor 9 (Sox9), and quantified epiphyseal trabecular parameters. Compared to the young age group, elderly mice showed an increased OARSI score, decreased chondrocyte columns of the growth plate, elevated expression of OA markers (aggrecan fragments, MMP13, and COL10A1), and decreased expression of Sox9 at the articular cartilage region in elderly STR/ort mice. Aging also significantly enhanced the subchondral bone remodeling and microstructure change in the tibial plateau. Moreover, GRGDS treatment mitigated these subchondral abnormalities. Our study presents suitable evaluation methods to characterize and measure the efficacy of cartilage damage treatments in STR/ort mice with spontaneous OA.

Time-resolved ICP-MS analysis of mineral element contents and distribution patterns in spermatogenic cells of different types

Mineral elements play an important role in the spermatogenesis, maturation, and fertilization of sperm. It is of great scientific significance to study the role of mineral elements in spermatogenesis by accurately measuring the content of elements in different spermatogenic cells and analyzing the distribution pattern of elements in spermatogenesis. Here, time-resolved inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze the content and distribution patterns of mineral elements in spermatogenic cells of different types at the single cell level. Firstly, spermatogonia, spermatocytes, round spermatids and elongating spermatids were successfully isolated from testis of mice of different weeks of age by differential adherent method and discontinuous bovine serum albumin (BSA) density gradient method. Then, signal profiles and elemental distributions of 24Mg, 31P, 52Cr, 55Mn, 56Fe and 66Zn in spermatogenic cells were obtained with dwell time at 0.1 ms. Based on the results of acid digestion, we derived a formula to calculate element content in single cell from peak area for each element, and the feasibility and universality of the formula in the quantitative detection of single cell elements were verified by sperm samples to a certain extent. The detection results of element content in single cell showed that the content of 31P in elongating spermatids was significantly higher than that in spermatogonia, spermatocytes and round spermatids (P < 0.01), and the distribution range was wider. However, the 52Cr and 56Fe content of elongating spermatids was lower than that of spermatogonia, spermatocytes and round spermatids (P < 0.05). When spermatogonia developed into round spermatids, the contents of 55Mn and 66Zn in single cell increased significantly (P < 0.05), then decreased to the lowest in elongating spermatids. In addition, the significant decrease of 52Cr, 55Mn, 56Fe and 66Zn content in elongating spermatids also be visually observed from the center of the fitting curve of the element signal intensity distribution moving to the left. This study provides an elemental view of the changes in elemental content at various stages of spermatogenesis at the single-cell level. Time-resolved ICP-MS is used to detect mineral elements content and distribution patterns in spermatogenic cells of testis, which is helpful to better explore the stages and modes of action of various elements in spermatogenesis, and provide direct evidence for revealing the effects of element content changes on spermatogenesis and semen quality regulation.

Genome-Wide Association Study and Selective Sweep Analysis Reveal the Genetic Architecture of Body Weights in a Chicken F2 Resource Population.

Rapid growth is one of the most important economic traits in broiler breeding programs. Identifying markers and genes for growth traits may not only benefit marker-assisted selection (MAS)/genomic selection (GS) but also provide important information for understanding the genetic architecture of growth traits in broilers. In the present study, an F2 resource population derived from a cross between the broiler and Baier yellow chicken (a Chinese local breed) was used and body weights from 1 to 12 weeks of age [body weight (BW) 1–BW12)] were measured. A total of 519 F2 birds were genome re-sequenced, and a combination of genome-wide association study (GWAS) and selective sweep analysis was carried out to characterize the genetic architecture affecting chicken body weight comprehensively. As a result, 1,539 SNPs with significant effects on body weights at different weeks of age were identified using a genome-wide efficient mixed-model association (GEMMA) package. These SNPs were distributed on chromosomes 1 and 4. Besides, windows under selection identified for BW1–BW12 varied from 1,581 to 2,265. A total of 42 genes were also identified with significant effects on BW1–BW12 based on both GWAS and selective sweep analysis. Among these genes, diacylglycerol kinase eta (DGKH), deleted in lymphocytic leukemia (DLEU7), forkhead box O17 (FOXO1), karyopherin subunit alpha 3 (KPNA3), calcium binding protein 39 like (CAB39L), potassium voltage-gated channel interacting protein 4 (KCNIP4), and slit guidance ligand 2 (SLIT2) were considered as important genes for broiler growth based on their basic functions. The results of this study may supply important information for understanding the genetic architecture of growth traits in broilers.

Genetic Evaluation of Growth Traits in New Synthetic Rabbit Line in Egypt

Native Middle Egypt Rabbit breed (NMER) crossbred with Gaint Flander rabbits to create a synthetic line and this study aimed to evaluate the genetic estimates of this synthetic line with comparing to the purebreds. A crossbreeding was carried out by mating bucks of Gaint Flander (G) with does of NMER (N) to get F1 (½N½G), then does and bucks of F1 were mated to get the F2 (½N½G)2, followed by two generations of inter se-mating to get a new synthetic line is called Egy-line with a genetic structure of ((½N½G)2)2. Heritability estimates for body weights were generally moderate and ranging from 0.10 to 0.24, while the estimates of heritability for growth rate were low and moderate and ranging from 0.01 to 0.23. Common litter effects of body weight were large as weaning (0.61), then declined gradually at the rabbit grew older. Also, the same trends were observed for relative growth rate (RGR). The direct additive effects were positive and highly significant for all body weights at different ages, favoring Gaint Flander and heavier comparing with NMER rabbits. Most relative growth rates during different intervals were non-significant. Gaint Flander was highly significantly and heavier in maternal additive effects in in different weeks of age comparing with NMER rabbits. Direct heterosis effect for most bodyweight was positive and highly significant, and percentages of direct heterosis increased generally with the advance of age. Maternal heterosis for growth rates from 5 to 6, 8 to 10, and 10 to weeks were positive, only. Direct recombination effects for most bodyweight were positive and highly significantly exclude weight at 5 and 6 weeks. It is concluded that a new synesthetic line (Egy-line) has proven its superiority and performance well in all different body weights and most growth rates compared to other parents and crossbreds.

Age-associated changes in caecal microbiome and their apparent correlations with growth performances of layer pullets.

The microbiome in gastrointestinal tracts play an important role in regulating nutrient utilization and absorption, gut immune function, and host growth or development. This study was conducted to investigate the composition and dynamic distribution of caecal microbiota in pullets during the first 16 weeks. Growth performance, immune organs index, and intestinal morphology of pullets were analyzed at 3, 6, 12 and 16 weeks of age. The caecal contents were collected for microbiota analysis by 16S rRNA gene sequencing method. With advancing ages in pullets, the gradually increased average daily feed intake (ADFI), feed conversion ratio (FCR) and intestinal villus height, but the gradually decreased organs index of thymus and bursa were determined. Meanwhile, more abundant caecal bacterial communities were determined from pullets at 12 and 16 weeks of age than those at 3 and 6 weeks of age. Furthermore, the dominant microflora of pullets from different weeks of age were analyzed by using LEfSe: The higher abundance of Blautia, Prevotella, Alistipes, and Eggerthella were found at 6 weeks; Anaerostipes, Oscillospira, Enterococcus and Methanobrevibacter were determined at 12 weeks; and the higher abundance of Parabacteroides, Anaerofustis, Lactobacillus and Butyricimonas were determined at 16 weeks. Further functional predicted analysis by PICRUSt revealed that the endocrine system and carbohydrate metabolism were significantly developed at 3 weeks. The development of the immune system was predicted to be mainly during 6 to 12 weeks, while cardiovascular diseases and circulatory system were during 12 to 16 weeks. In addition, the significantly negative correlation between Bacteroides and villus height, the significantly negative correlation between growth parameters (ADFI and FCR) and Bacteroides, Oscillospira and Alistipes; and the significantly positive relations between growth parameters (ADFI and FCR) and Bilophila, Lactobacillus, Rikenella and Anaerofustis were determined by using Pearson analyses. In conclusion, our data demonstrated that growth performance and intestinal morphology correlate well with caecal microbiota, which could provide new insights to establish or develop nutritional strategies to manage the intestinal health or development of laying pullets.

Comparison of metabolic and functional parameters using cardiac 18F-FDG-PET in early to mid-adulthood male and female mice

BackgroundIn this descriptive study of male and female mice at different weeks of age, we use serial non-invasive cardiac 18F-FDG-PET scans to follow up on metabolic alterations, heart function parameters, and the ECG of both sexes in early to mid-adulthood.MethodsECG-gated 18F-FDG-PET scans were performed in mice on 10, 14, and 18 weeks of age, using a dedicated small-animal PET scanner. The percentage of the injected activity per gram (%IA/g) in the heart, left ventricular metabolic volume (LVMV), myocardial viability and left ventricular function parameters: end-diastolic (EDV), end-systolic (ESV), stroke volume (SV), and the ejection fraction (EF%) were estimated.ResultsCompared to their age-matched female counterpart, male mice showed a constant increase in LVMV and ventricular volume during the follow-up. In contrast, female mice remain stable after ten weeks of age. Furthermore, male mice showed lower heart rates, positive correlation with cardiac %IA/g, and negative correlation with LVMV.ConclusionIn this study of serial cardiac PET scans, we provide insight for basic murine research models, showing that mice gender and age show distinct cardiac metabolisms. These physiologic alterations need to be considered when planning in vivo injury models to avoid potential pitfalls.

Production performance and egg quality in Kuzi ducks of Odisha

Production performances and egg quality parameters of Kuzi ducks of Odisha were studied in 40 drakes and 240 duck sinintensive system of rearing under hot and humid climate conditions. The body weight recorded at first egg of the flock was 1568±3.76g in ducks and 1730±43.45g in drakes. First egg of the flock was obtained at 110.67±3.76 days and age at 50% duck house egg production was 135.33±5.60 days. Age of the flock at peak (90%) duck house egg production was 167.67±6.06 days. Duck day egg production calculated at 4 weeks interval revealed that there is no definite trend however, as the age advances there was a decrease in egg production % after 60 weeks of age. The egg weight increased with the ages and the egg weight at 40 weeks of age was 64.26±0.48g. The egg production of the duck up to 40 weeks of age was 110.79±4.42 eggs and up to 72 weeks of age were 217.68±4.96 eggs. Significant differences inegg weight, shape index, albumen index, yolk colour, shell thickness and Haugh unit score were observed at different weeks of age. Further, as the age of the bird advances there was decrease in Haugh unit and albumen index with increase in egg shell thickness. The internal quality decreased with increase in age of the bird. The production performance showed that the Kuzi ducks may be used as an egg type ducks.

Genetic analysis on body weight at different ages in broiler chicken raised in commercial environment.

A multivariate model was developed and used to estimate genetic parameters of body weight (BW) at 1-6weeks of age of broilers raised in a commercial environment. The development of model was based on the predictive ability of breeding values evaluated from a cross-validation procedure that relied on half-sib correlation. The multivariate model accounted for heterogeneous variances between sexes through standardization applied to male and female BWs differently. It was found that the direct additive genetic, permanent environmental maternal and residual variances for BW increased drastically as broilers aged. The drastic increase in variances over weeks of age was mainly due to scaling effects. The ratio of the permanent environmental maternal variance to phenotypic variance decreased gradually with increasing age. Heritability of BW traits ranged from 0.28 to 0.33 at different weeks of age. The direct genetic effects on consecutive weekly BWs had high genetic correlations (0.85-0.99), but the genetic correlations between early and late BWs were low (0.32-0.57). The difference in variance components between sexes increased with increasing age. In conclusion, the permanent environmental maternal effect on broiler chicken BW decreased with increasing age from weeks 1 to 6. Potential bias of the model that considered identical variances for sexes could be reduced when heterogeneous variances between sexes are accounted for in the model.

Age-Related Changes in DNA Methylation Associated with Shifting Th1/Th2 Balance.

This study was conducted in order to explore age-related changes in the production of Th1 and Th2 cytokines and determine the corresponding status of DNA methylation. The plasma IL-4 and IFN-γ levels and expression of Th-related cytokines and transcription factors in CD4+ splenocytes were observed in mice at different weeks of age. The DNA methylation levels of IL-4 and IFN-γ promoters and the related regulatory regions in CD4+ splenocytes of mice at different weeks of age were analyzed. The DNA methyltransferase (DNMT) levels in CD4+ splenocytes of mice were analyzed. Changes in plasma IL-4 and IFN-γ levels after 5-AZA injection were evaluated. Plasma IL-4 and IL-4 expression in CD4+ splenocytes declined with increasing age, while the IFN-γ expression levels increased. Th-related transcription factors showed no differences in mice at different weeks of age. The DNMT1 and DNMT3b mRNA expression did not show significant changes in CD4+ splenocytes, whereas the DNMT3a mRNA expression increased with age. DNA methylation in the IL-4 promoter was increased, while DNA methylation in the IFN-γ promoter was decreased. The methylation of RSH7, CNS-1, and HSV increased significantly with age. Age-related changes in DNA methylation may be associated with the shift in Th1/Th2 balance.

Longitudinal analysis of body weight, feed intake and residual feed intake in F2 chickens

The aim of this study was to estimate covariance functions, using B-spline random regression models for body weight (BW), feed intake (FI) and residual feed intake (RFI) in F2 chickens. Feed intake and body weight were recorded on each bird every week from 2 to 10 weeks of age. The F2 population was derived from a cross between a fast growing Arian broiler line and Iranian native fowl. Sex, hatch and age in week were fitted as fixed effects and additive genetic and permanent environment as random effects. Variance components were estimated by the means of a Bayesian analysis, using Gibbs sampling. Covariance components for cumulative FI and RFI were obtained as a function of week on test. The heritability estimates for BW ranged from 0.19 to 0.34 and were high at the early ages, decreases with age to a moderate value. A similar pattern was observed for FI, where the heritabilities decreased from 0.29 to 0.12 from the second week to 10th week of age. Estimates of heritabilities for RFI along the growth trajectory ranged from 0.10 to 0.29 and increased over the time. Cumulative FI and RFI had medium to high heritability (0.24 and 0.41, respectively). The posterior means of genetic correlations between BW at different age were moderate to high from 2 to 10 weeks of age, ranging from 0.26 to 0.99. These estimates for phenotypic correlations were lower than the corresponding genetic correlations for all the weeks. The posterior means of genetic correlations between different weeks of age ranged from 0.10 to 0.99 for FI and −0.15 to 0.96 for RFI. The genetic and phenotypic correlations consistently decreased as the time interval increased for all traits. However, for the cumulative FI and RFI traits were increased with increasing the age interval from 2 to 9 weeks of age. The genetic correlations and expected response to indirect selection showed that the optimum test length for FI and RFI can be reduced to 2 weeks without a large loss in overall genetic gain in FI or RFI. In general, spline model showed that there was genetic variation in the BW, FI and RFI curve of individual chicken. The results indicated that random regression models can provide a good description of the data and is recommended for genetic selection in chickens.

Evaluation of four different crossbreds developed for backyard poultry farming under intensive system

In the present study, 4 new crosses, viz. PD1× PD4 (A), PD1 × PB2 (B), PD1x PD3 (C) and PD1 × IWI (D) were developed and evaluated under intensive system of rearing. Body weights, conformation traits were evaluated during starter and growing period and production performance were measured up to 72 weeks of age. Body weights at day 0, 2, 4, 6, 7 and 8 weeks of age in the starter period and at 10, 12, 14, 16, 18 and 20 weeks of age during growing period differed significantly between crosses in both male and female. Irrespective of age, cross B recorded higher body weight compared to other crosses. Shank length and keel length measured at 6, 8, 18 and 20 weeks of age in both the sexes differed significantly between the crosses. The maximum shank and keel lengths were achieved by 20 weeks of age. Feed conversion ratio (FCR) from 0–8 weeks of age was the best in B followed by A, C and D. The age at sexual maturity (ASM), weight at sexual maturity, body weight and shank length at 40 weeks of age, egg production up to 72 weeks of age differed significantly between different crosses. Egg weights measured at different weeks of age also differed significantly between the crosses. The egg production up to 72 weeks of age was the highest in C followed by D, A and B. Mortality % was lowest in D at different period. The results indicated that B may be useful for coloured meat type birds in rural areas whereas C and D cross may be useful for egg type as well as dual purpose backyard poultry. Cross A may be useful for dual type backyard poultry.

Differential modulation of AMPK/PPARα/UCP2 axis in relation to hypertension and aging in the brain, kidneys and heart of two closely related spontaneously hypertensive rat strains.

We examined expression protein of AMPK/SIRT1/PGC1α/PhoxO3a/PPARα/UCP2 pathway in brain, kidneys and heart of stroke-prone spontaneously hypertensive rat (SHRSP) vs stroke-resistant SHR (SHRSR) at different weeks of age, up to one year, in order to test the hypothesis that abnormalities within this pathway could associate with higher susceptibility of SHRSP to develop hypertension-related vascular damage. SHRSP develops severe hypertension and related target organ damage. Marked reduction of uncoupling protein 2 (UCP2) expression upon high salt-low potassium diet associates with increased renal injury in SHRSP. UCP2 may represent a key mitochondrial protein involved in cardiovascular damage. At 2 months of age a significant down-regulation of UCP2 expression at both mRNA and protein levels was found, along with reduced protein expression of all components of UCP2 regulatory pathway, in tissues of SHRSP but not of SHRSR, that progressed with hypertension development and aging. A significant increase of both oxidative stress and inflammation was detected in tissues of SHRSP as a function of age. SBP levels were significantly higher in SHRSP than SHRSR at 3 months of age and thereafter. At one year of age, higher degree of renal damage, with proteinuria and severe glomerular and tubulo-interstitial fibrosis, of cerebral damage, with significant vessel extravasation and stroke occurrence, and of myocardial damage was detected in SHRSP than SHRSR. The early significant reduced expression of the antioxidant AMPK/PPARα/UCP2 pathway that progressed throughout lifetime may contribute to explain higher predisposition of SHRSP to oxidative stress dependent target organ damage in the context of severe hypertension.

Insulin resistance caused by lipotoxicity is related to oxidative stress and endoplasmic reticulum stress in LPL gene knockout heterozygous mice

ObjectiveTo investigate the correlation of hypertriglyceridemia with abnormal glucose metabolism and insulin resistance. MethodsLipid and glucose metabolism, whole-body and tissue-specific insulin sensitivity, genes and proteins related with oxidative stress and endoplasmic reticulum (ER) stress were compared between LPL+/− and control mice at different weeks of age. Results16–50-week LPL+/− mice had increased body weight compared with their respective controls. Fat mass in visceral adipose tissue (VAT) of 16 and 28-week LPL+/− mice were twice more than their control littermates, and 50-week LPL+/− mice showed the same trend of increase. Plasma lipids were higher in 16–50-week LPL+/− mice. 28- and 50-week LPL+/− mice had elevated tissue lipid accumulation (liver, skeletal muscle, pancreas) and impaired glucose tolerance, while 16-week LPL+/− mice showed no differences. Homeostasis model assessment of insulin resistance for 28 and 50-week LPL+/− mice were twofold greater, whereas that for 16-week LPL+/− mice had no change. Insulin-stimulated phosphorylated Akt (Ser473) in VAT of 28-week LPL+/− mice decreased by 80.6% (p = 0.001), and that in liver and skeletal muscle decreased by 62.4% (P < 0.001) and 51.8% (p = 0.005) respectively. Then we found that plasma malondialdehyde and reactive oxygen species levels in liver and skeletal muscle of LPL+/− mice were elevated. Increased ER stress biomarkers were also detected in liver and VAT of 28-week LPL+/− mice. ConclusionsSystemic LPL deletion results in impaired glucose tolerance, whole-body and tissue-specific insulin resistance, which is associated with tissue lipid deposition in various insulin target tissues. Furthermore, the activation of oxidative stress and ER stress may play an important role in the development of tissue-specific and systemic insulin resistance.

Change Trends of Organ Weight Background Data in Sprague Dawley Rats at Different Ages

Organ weight is one of the most sensitive drug toxicity indicators, and its changes often precede morphological changes. So far, no background data about organ weight and its coefficient in SD rats at different weeks of age have been reported in China. The aim of this study was to summarize and analyze the change trends of organ weight and organ weight coefficients in SD rats at different weeks of age. The absolute of the weights of the brain, spleen, heart, lungs, liver, kidneys, adrenal glands and testes were increased in male SD rats from 13 to 78 weeks, and the weights of the brain, heart, lungs, liver, kidneys and especially the testes were decreased from 78 to 104 weeks. On the other hand, the absolute weight of the adrenal glands showed an increasing trend from 13 to 104 weeks. The absolute weight of the brain, spleen, heart, lungs, liver, kidneys, adrenal glands and ovaries showed an increasing trend from 13 to 104 weeks. A significant increase was observed in adrenal gland and ovary weights, whereas no obvious change trends were observed for the other organ weights mentioned above. It was surprising that the absolute of weight of the adrenal glands and organ-to-brain and organ-to-body weight ratios in female rats were significantly higher than those in males from 13 to 104 weeks. This study was the first to establish background data for organ weights in SD rats at different weeks of age and their reference ranges in line with the experimental animal status in China and to summarize their summarized their changes trend.

Genetic effect of the follicle-stimulating hormone receptor gene on reproductive traits in Beijing You chickens

We analyzed the effects of the polymorphisms of the follicle-stimulating hormone receptor (FSHR) gene on egg production in a Beijing You chicken population divergently selected for egg number, egg weight, and BW across 3 generations. The FSHR gene encodes the receptor of follicle-stimulating hormone, which controls follicular development and recruitment in the ovary. Seven SNP of the FSHR gene were investigated in 768 pedigreed hens from the G2 generation. Association analysis revealed that g.-310A > G, g.-181A > T, and g.159C > T were associated with egg number at different weeks of age (P < 0.05) and that g.75470A > G and g.75860G > A were associated with egg weight at first egg (P < 0.05). The favorable allele of g.-181A > T and g.159C > T had increased frequencies not only in the high line but also over the 2 generations (G2 vs. G1) within the high line. To confirm the association study, we tested for FHSR mRNA expression level in the chicken ovaries. The results showed that the homozygous favorable genotypes of g.-181A > T and g.-310A > C increased the FSHR mRNA expression level compared with the other genotypes (P = 0.001 and P = 0.026, respectively). Hence, our findings implied that the SNP g.-181A > T could be a potential genetic marker for egg performance in the Beijing You chicken, but further replications of our study in other chicken populations are needed to verify such effects detected here.

動脈硬化進展因子としてのnonenzymatic glycosylation

The Maillard reaction, a nonenzymatic glycosylation is nonspecific binding reaction of sugar to protein. The extent of this glycosylation was estimated by determining furosine, which is a hydrolysate of fructose-lysine. Nonenzymatic glycosylation of the rat aorta increased with advancing age in the range of up to 50 weeks. Nonenzymatic glycosylation level of aorta in streptozotocininduced diabetic rats also increased with advancing age in the range of up to 50 weeks. No significant difference was found in hemoglobin A1 levels among rats at different weeks of age, except rats at 4 weeks of age. However, nonenzymatic glycosylation level in diabetic rats was significantly higher than that found in normal rats at the same weeks of age. It is considered that the Maillard products can be regarded as a sort of cross-linking compounds between protein and sugar. Furthermore, the Maillard reaction proceeds slowly over a long period of time. Therefore, these results suggested that nonenzymatic glycosylation of artery may become an accelerating mechanism of arteriosclerosis in diabetic patients.