Months Of Freezing Research Articles

Dosing in Three Levels of Apricot Seed Oil and Its Affects on Some Fresh and Frozen Sheep Meat Traits

Its impact on some characteristics of frozen meat from Iraqi sheep. The experiment was carried out at the Animal Production Field of the College of Agriculture, Tikrit University, from August 22, 2023, to December 2, 2023. Fifteen lambs were used, divided into three groups (five lambs per group) with similar average weights (24.40 kg). The treatments were randomly assigned, and a collective feeding system was employed using a single formula of concentrated feed at 3% of the live animal's weight. The results indicated a significant difference (P≤0.05) in the moisture content favoring the first treatment over the second and third treatments. Conversely, the third treatment showed a significant increase (P≤0.05) in fat percentage, ash content, and protein content compared to the first treatment. The administration of apricot oil at 0.0020% of the live animal's weight led to a reduction in lipid peroxidation and post-thaw loss after two months of freezing. The results also showed significant differences in the free fatty acid profiles (Palmitic, Stearic, Oleic, Linolenic, Linoleic, and Myristic) in the frozen meat samples, with the third group of animals showing significant superiority (P≤0.05) over the other groups after two months of freezing.

Comparing the Addition of Different Levels of Lemon Verbena Leaves Powder (Aloysia citriodora) and the Antibiotic Oxtetracycline to Diets Broiler in the Qualitative Traits of Broiler Carcasses

From October 29, 2022, to December 10, 2022, researchers from the University of Baghdad’s College of Agricultural Engineering Sciences monitored birds at the Abu Ghraib chicken farm as part of a 42-day comparative study. Analyzing the effects on the quality of broiler meat from varying amounts of oxtetracycline and lemon verbena leaves powder (aloysia citriodora) in their meals. Three hundred commercial hybrid broiler chicks (ROSS 308) were employed, all of which were unnaturalized at one day old and had an initial weight of 42.42 g/chicken. T1 chicks were fed a standard broiler diet without any additives, T2 chicks were fed diets containing 250 mg of oxytetracycline antibiotic powder per kilogram of body weight, and T3 chicks, T4 chicks, and T5 chicks were fed diets containing 1%, 1.5%, and 2% of aloysia citriodora leaves extract powder. There were no unethical changes in live weight or carcass weight between transactions (p>0.05), but the clearing ratio for the third transaction was much better than the rest of the transection. This study also demonstrated the beneficial effect of adding powdered lemon verbena leaves on flavor oxidation markers after two months of freezing, with a marked reduction in comparison to both the control treatment and the antibiotic treatment.

FAT OXIDATION, PROTEIN DEGRADATION AND COLOUR OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) MEAT DURING 3 MONTHS OF FREEZER STORAGE

The aim of the work was to analyze the effect of storage in freezing conditions (-18 ° C) during 3 months of storage on the formation of malondialdehyde MDA, TVB-N (total volatile basic nitrogen), and colour. Rainbow trout up to 500 g (RT) aged 1-1.5 years (n=15) and trout (RT1) up to 3.5 kg aged 2-2.5 years (n=15) were included in the experiment. The stated weight of the fish is already after processing. After slaughtering the fish, samples were taken from each fish for analysis of meat colour in the CIE colour space with a KONICA MINOLTA 2600D (L*, a*, b*) on the 1st day after slaughter and after the 1st, 2nd, 3rd month of storage. The content of TVB-N and MDA was measured parallel. For both weight categories of trout, after three months of freezing, we observed significant (RT1- P≤0.05; RT- P≤0.05) increase in TVB-N compared to the first day of measurement. Malondialdehyde content after three months of freezing was significantly (P≤0.05) higher than at the first measurement in both weight categories of rainbow trout. In the RT experimental group, trout meat after three months of freezing was significantly (P≤0.05) lighter (L*) and less yellow (b*). The meat of the RT1 group after 3 months of freezing storage was significantly (P≤0.05) darker , less red and less yellow.

Heavy Metal Concentrations in Imported Frozen European Hake Merluccius merluccius (Linnaeus 1758)

This research looked at the concentration levels of some heavy metals in tissues and organs of imported frozen European hake Merluccius merluccius (Linnaeus, 1758). This to ascertain the safety of the fish for consumption and whether long time freezing could bio concentrate heavy metals in the fish. Fish were procured from the market, muscles, gills and liver removed, digested for analysis of Cu, Zn, Mn, Fe, Cd, and Pb using AAS. Fe was the most accumulated metal with 4.393±0.19 mg/kg, Cadmium (Cd) was the least with 0.004±0.00 mg/kg (Fe>Zn>Cu>Pb>Cd>Mn). Muscle accumulated the most metals. Concentrations of the metals were below maximum limit recommended by Food and Agricultural Organization/World Health Organization (FAO/WHO), which shows the fish is safe for consumption. It also showed that long time freezing does not bio concentrate heavy metals in the fish about a month of freezing. It is recommended that regulatory authorities should always conduct an assessment of the heavy metals in imported frozen marine fishes before it is cleared for human consumption. This will guide against any adverse health risk associated with consumption of fish with high levels of heavy metals.

The dynamic change in the degradation and in vitro digestive properties of porcine myofibrillar protein during freezing storage

The myofibrillar protein (MP) degradation and in vitro digestive properties of porcine longissimus during freezing at −8, −18, −25 and − 40 °C for 1, 3, 6, 9 and 12 months were investigated. As the freezing temperature and duration of frozen storage increased, the amino nitrogen and TCA (trichloroacetic acid)-soluble peptides of the samples were significantly increased, while the total sulfhydryl content and band intensity of myosin heavy chain, actin, troponin T, tropomyosin were significantly decreased (P < 0.05). At higher freezing storage temperatures and durations, the particle size of MP samples and the green fluorescent spots detected using a laser particle size analyzer and confocal laser scanning microscopy became large. After 12 months of freezing, the digestibility and the degree of hydrolysis of the trypsin digestion solution of the samples frozen at −8 °C were significantly decreased by 15.02 % and 14.28 %, respectively, when compared to fresh samples, whereas, the mean surface diameter (d3,2) and mean volume diameter (d4,3) were significantly increased by 14.97 % and 21.53 %, respectively. Therefore, frozen storage induced protein degradation and impaired the ability of digestion in the pork proteins. This phenomenon was more evident as the samples were frozen at high temperatures over a long storage period.

Effect of feeding sage meal to weaned Awassi male lambs on body performance and meat quality

An experiment was conducted for 8 weeks on 15 Awassi lambs using sage dry meal. Animals were randomly allocated into 3 groups [CGM (0% sage; Salvia officinalis), EGM1 (1% sage) and EGM3 (3% sage)] by 5 heads. Feed intake at the 8th week increased proportionally with LBW. Cumulative live body weight gain increased slightly more in EGM3 after the 5th week to attain 10.7 Kg at 8th week. FCR was most effective and attained 3.83 ± 0.97 in EGM3 Vs 4.14 ± 0.53 and 4.15 ± 0.64 in CGM and EGM1, respectively. After cooling, luminance ranged between 45.41 ± 2.97 in CGM and 47.28 ± 5.63 in EGM1 where as in EGM3 it was 47.28 ± 5.63. Redness, a*, after cooling was lowest in EGM3 (20.15 ± 3.29) followed by CGM (22.61 ± 3.41) and EGM1 (24.97 ± 1.24). Yellowness b* after 1 month of freezing is positively correlated with the achieved results after 24 h of cooling. The least losses in water after cooling was in EGM3 attaining 11.39 ± 2.39%. Meat of CGM loses more water after cooking (30.30 ± 6.52%) than other groups. Furthermore, after 24 hours of cooling, the most tender meat was in EGM1 (4.87 ± 0.44mm) in comparison to CGM (3.3 ± 0.64mm), whereas EGM3 occupied the 1st place in cooked meat tenderness after 1 month of freezing (5.4 ± 0.8mm). It is concluded and recommended to use rations containing sage meal in the daily feeding of Awassi sheep.

Sustainable Consumption Using the Example of Food Processing in a Restaurant

While strategy is of great importance in the hospitality industry, this article is in regard to the process. Therefore, for the first time, this article examines how stuffed yellow peppers are frozen (congelé) and later served as a portion of hot food in restaurants. A sensory analysis was performed, and tasters were invited. Data were collected over three different periods that represented the duration of freezing. The results of the descriptive statistical analysis indicated that the evaluated frozen dishes exhibited degrees of sensory deterioration. The findings are critical to the restaurant business because recipes are often skipped, and the process depends solely on the chefs. The primary value added for management is that strict recipes could improve the cost and shelf life of meals prepared and then frozen in the restaurant by lowering the storage temperature or shortening the freezing time. Incidentally, such analysis should be a continuous development to reduce energy consumption and increase food quality. The consistent results first demonstrated a decreased mouthfeel of the sauce after the first month and, second, a higher stickiness after two months of freezing. In addition, the nutritional values of the dish were calculated using trademarked software.

Development of Frozen Pulps and Powders from Carrot and Tomato by-Products: Impact of Processing and Storage Time on Bioactive and Biological Properties

Vegetables and fruits have an interesting nutritional profile, rich in bioactive metabolites, holding a high antioxidant potential and health associated benefits. However, their functional properties, the shorter shelf-life due to their high-water content, and their seasonality nature lead to extensive food losses and waste. The valorization of vegetables and fruits by-products through the development of value-added products and the application of preservation methods is of utmost importance to prevent food losses and waste. In this study, based on a circular economy approach, pulps and powders of baby carrot and cherry tomato by-products were prepared. Freezing, hot air drying and storage time impact on antioxidant activity and bioactive compounds were studied. Microbiological quality and pulps viscosity were also monitored for 6 months. During the freezing storage, TPC and antioxidant capacity by ABTS and ORAC assays decreased. The antioxidant capacity by DPPH method and carotenoid content increased during the first months of freezing, but then decreased. The drying process negatively affected the antioxidant capacity as well as carotenoid and polyphenolic content compared with the fresh vegetables. Both processing methodologies positively impacted the vitamin E content. During drying storage, there were no key variations in antioxidant capacity and bioactive content.

GENETIC PARAMETERS IN SEED CHARACTERS OF Ormosia discolor UNDER DIFFERENT AMBIENT CONDITIONS

Ormosia discolor Spruce ex Benth. is a native tree of the Amazon with has fast growth and nodulation capacity, whose seeds are used for craftwork. The objective of this study was to estimate genetic parameters in seed characters of O. discolor at different ambient temperatures and to indicate superior matrices to compose seed lots. Seeds of 20 progenies selected from a population in the state of Amazonas were collected. Three experiments were performed under different ambient temperatures at the Seed Center laboratory/UFAM. Experiment 1 was performed at constant temperature of 30 °C. In experiment 2, seeds were submitted to a temperature of 35 °C. In experiment 3, after five months of freezing, the seeds were submitted to a temperature of 30 °C. The experimental design was completely randomized, consisting of 20 progenies, four replicates, and 25 seeds per plot. The germination characters evaluated were germination rate, mean germination time, and synchronization and speed germination indexes. Genetic and phenotypic variances and correlations, broad-sense heritability, and genetic gain through direct selection were estimated. O.discolor progenies showed significant genetic variability for most of the characters evaluated. High heritability and accuracy values (&gt; 90%) were found for germination rates at all ambient temperatures. Matrices 2, 7, and 16 were superior for germination characters at all temperatures tested, being indicated for seedling production. Eighteen O. discolor seeds are sufficient for biometric analysis with accuracy of 95% in genotype selection.

Effect of Freezing and Thawing on Human Milk Macronutrients and Energy Composition: A Systematic Review and Meta-Analysis.

Objective: To conduct a systematic review of the effect of freezing and thawing on the macronutrients and energy composition of human milk (HM). Design: Systematic review conducted in May 2019, including all studies reporting macronutrients and energy composition of HM, according to a search of MEDLINE, EMBASE, and Google Scholar using the keywords: HM, breast milk, macronutrients, fat, lipid, protein, carbohydrates, energy, calories, freezing, thawing, and of the references in studies identified as potentially relevant. Meta-analyses were conducted in all the studies that reported one or more of the following: total energy, true protein, fat, and carbohydrates. They were reported according to following groups of freezing duration: 1-7 days, 8-30 days, 31 days-3 months, and >3 months. They were calculated and expressed as weighted averages with pooled standard deviations. Results: Eight studies remained in the final analysis. Regression analyses did not find any significant increase or decrease over time of protein content, lactose content, fat content, or energy content of milk. Conclusions: No dramatic changes in macronutrients and energy contents of milk are expected to occur within the first few months of freezing.

Browning Prevention and Sensory Evaluation of Frozen Yam Slices (Dioscorea cayenensis-rotundata Cv Kponan) of Côte D’Ivoire

Aim: To prevent enzymatic browning during the freezing of yam slices of the Kponan variety (Dioscorea cayenensis-rotundata).&#x0D; Study Design: The experimental set-up was of a completely randomized design.&#x0D; Place and Duration of Study: Department of Food Science and Technology, Food Biochemistry and Tropical Products Technology Laboratory (BATPTL), University of Nangui Abrogoua, Abidjan, Côte d’Ivoire, between August and December 2018.&#x0D; Methodology: For this purpose, yam slices were either pretreated with a natural agent (lemon juice solution at different pH) or pretreated and blanched (85 °C for 2 min) and then packed in plastic bags and kept in the freezer at -18°C over a period of 4 weeks. Polyphenoloxidase and Peroxidase activities, Dry matter, rate of browning and sensory attributes of yam slices were determined.&#x0D; Results: The results showed a decrease in polyphenoloxidase and peroxidase activities regardless of the treatment. The largest decreases in activity were observed in yam slices that were both pretreated and blanched compared to the control (about 53.49% decrease in the specific activity of the PPOs and 51.46% of POD). The combination of pretreatment and blanching also resulted in lower dry matter yam slices compared to pretreated slices only. After 1 month of storage in the freezer, the lower rates of loss (browning) were recorded for the slices of yams that were both pretreated and blanched compared to the other methods which had very high losses. The pretreated and blanched slices had high dry matter content. The sensory profile of slices processed by the combined technique after one month of freezing had a good appreciation for all sensory characteristics of yam.&#x0D; Conclusion: In order to have a good product, the combined method is recommended for better freezer storage of yam slices.

Development of a human milk concentrate with human milk lyophilizate for feeding very low birth weight preterm infants: A preclinical experimental study.

Breast milk is considered the gold standard nutritional resource for very low birth weight (VLBW) infants in terms of nutrients and protective factors. If mother's milk is not available, the second choice is donated and fortified human milk (HM) from the Human Milk Bank (HMB). This study hypothesized that HM could be lyophilized and used as an additive to increase the levels of macronutrients and micronutrients available to VLBW infants. This study aimed to constitute a lyophilized HM concentrate and determine the osmolality and the concentration of macronutrients and micronutrients in HM samples at “baseline” and in “HM concentrates”, analyzed immediately (HMCI), and after 3 (HMC3m) and 6 (HMC6m) months of freezing. Osmolality was verified using the freezing point osmometric method. Macronutrient quantification was performed using the MIRIS Human Milk Analyzer. Micronutrients were determined by Flame Atomic Absorption Spectrophotometry and by the automated colorimetric method. Bayesian linear mixed effect models were adjusted using OpenBUGS to estimate mean differences and 95% credibility intervals (CrI) of osmolality and of macro- and micronutrients between the types of HM samples. A comparison of dosage values showed a significant increase between HM baseline and HMCI, HMC3m, and HMC6m. Comparing HM baseline and HMCI highlighted the increase in energy content and the concentration of carbohydrates and total lipids. The Ca and P contents increased and the levels of energy, total lipids, and Cu were reduced in HMC3m compared to HMCI. Ca, Mg, K, Zn, and P increased and the levels of energy, total lipids, and Cu were reduced in HMC6m, compared to HMCI. The present study confirms the possibility of formulation and utilization of the immediate concentrate. Partial stability of HM concentrates generated from freeze-drying of donated milk do not recommend storage.

Cryopreservation of lymphocytes for immunological studies in horses

ABSTRACT: The use of frozen cells allows studies on diseases and other immunological assays, since it facilitates the logistics of collecting and transporting, including laboratories located in different cities or other countries. The objectives of this study were to verify if the storage in the refrigerator after collection at different times changes the viability of total leukocytes after months of freezing and the ratio of CD4/CD8 is affected by the freezing process. Venous blood of 15 healthy horses was used and the experiment was divided into 2 stages. In the first, the viability of the leukocytes before and after freezing was verified, as well as different storage times in the refrigerator (fresh blood, stored for 24 and 48 hours) before the freezing process. In the second part, the immunophenotyping of the T lymphocytes was performed, in order to observe if after thawing the relationship between LT CD4 and LT CD8 undergoes change. There was no difference between the amounts of viable leucocytes from frozen fresh blood compared to fresh blood before freezing, nor difference between the viability of blood left in the refrigerator (4°C) for 24 hours and fresh blood and fresh frozen blood. There was a decrease in viability of frozen leukocytes after 48 hours left in the freezer for other samples; however, the recovery was 107x cells. Regarding the immunophenotyping of CD2CD4+ and CD2CD8+ double-labeled T lymphocytes in the blood stored in the refrigerator for 24 hours before freezing, no difference was observed between before and after 6 months of freezing. It is concluded that cryopreservation of equine total leukocytes is possible and, although there was a difference between freezing times, even in the less viable sample, sufficient numbers of cells were recovered for other immunological assays.

Effect of freezing on the quality of meat from broilers raised in different rearing systems

We evaluated the effect of freezing (−18°C) for 12 months on the qualitative characteristics of breast, thigh and drumstick meat. Samples from male Cobb 500 broilers raised in antibiotic-free (n = 125), conventional (n = 125) and organic (n = 125) rearing systems and samples from male Hubbard ISA broilers raised in a free-range (n = 125) rearing system were used. Among the studied systems, up to the ninth month of freezing, the organic chicken breast meat showed lower (P &lt; 0.001) water activity (aw) (0.966, on average). After 12 months of freezing, samples of antibiotic-free and organic poultry showed a pH value similar to that of fresh meat (5.94 and 5.86, respectively). Freezing for 12 months preserved the redness of drumstick meat from conventional broilers (a* = 4.86, on average) and the rearing system did not influence the aw of drumstick meat during the entire experimental period. Freezing preserved the aw of conventional and organic chicken meat samples until the ninth month of evaluation (0.978 and 0.974, respectively). Lipid oxidation in the breast, thigh and drumstick samples from the four rearing systems increased (P &lt; 0.001) from the third month of freezing onwards. There were variations in colour, pH, aw and lipid oxidation of chicken meat among birds raised in different rearing systems. Freezing chicken meat did not prevent colour and pH changes or occurrence of lipid oxidation and did not promote a reduction of aw to levels unfavourable to microbiological development.

Influence of the xanthan gum addition on the technological and sensory quality of baking products during the freezing storage

The influence of the 0.16% xanthan gum addition in the recipe of the bread production and its influence on the baking and sensory quality of products was monitored during the process of our research. Prepared dough was inserted in the freezing box directly (-18°C) and it was stored for one, two, three, four, five and six months. When the baking process was finished, the products with xanthan gum and the products without it were compared and evaluated by both objective and subjective methods. It was found that freezing, cooling and storage of the products without xanthan gum addition influenced the volume, vaulting and general appearance of the products in a negative way and loaves of bread were evaluated as unacceptable after four months of freezing. The quality of experimental loaves of bread with xanthan gum was, even after six months of freezing storage, comparable with freshly baked products. Despite the freezing, the volume of the products had an increased value. After first month of freezing the volume increased by 28.6% and after two months of freezing it increased by 23.8% both compared to the control. The vaulting in products processed by freezing was in the required optimal level during the whole period of freezing. Sensory evaluation results of loaves of bread with xanthan gum were the best after three, four and five months of storage in a freezer, when 98 points were achieved. During the monitored period of freezing, the addition of 0.16% of xanthan gum markedly contributed to the preservation of sensory and baking quality of the frozen wheat dough.

Effect of Long-Term Freezing and Freeze–Thaw Cycles on Indigenous and Inoculated Microorganisms in Dewatered Blackwater

Wastewater treatment in many Arctic regions is inadequate, even nonexisting. Natural freezing of wastewater in those areas may be beneficial for reduction of microorganisms. The aim of this study was to investigate the effect of long-term freezing, and repeated freezing and thawing, on indigenous coliforms, fecal streptococci, and antibiotic-resistant (AR) bacteria, and inoculated Salmonella Enteriditis and E. coli bacteriophage ΦX174 in dewatered blackwater. At the end of the long-term freezing experiment (10 months), an MPN recovery study was done, including the microbial groups that had shown the largest reduction, using tryptone soy broth at incubation temperatures of 10 and 20 °C overnight for the coliforms and AR bacteria, and buffered peptone water at incubation temperature of 37 °C for 18-20 h for Salmonella. Fecal streptococci were more resistant to long-term freezing than the coliform group. Total number of AR bacteria decreased slowly but constantly over the 10-month freezing period. Salmonella rapidly decreased and were nondetectable within a week but exhibited some recovery after 10 months of freezing, whereas limited or no recovery of coliforms and AR-bacteria was detected. Bacteriophages showed limited reduction during the long-term freezing. Repeated freezing and thawing increased the reduction of all tested microbial groups markedly.

Effect of freezing on quality of sea bass and gilthead sea bream

AbstractFreezing is an efficient method of fish preservation. The aim of the present work was to examine the impact of freezing in fatty acid composition and in the in vitro inhibitory activity of sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) fillet lipids against platelet activating factor (PAF). The Bligh and Dyer extraction method and the counter‐current distribution method were used to obtain total, polar and neutral lipids. The fatty acid analysis conducted using the internal standard method and the biological assay on washed rabbit platelets took place calculating the in vitro inhibitory activity of fish lipids against 2.5 × 10−11 M of PAF. No statistical changes (p&lt;0.05) occurred in fatty acid content of fresh and thawed gilthead sea bream, while fatty acid amount in thawed sea bass was significantly higher (p&lt;0.05) compared to fresh fish. Total lipids of both thawed fish species exhibited stronger anti‐thrombotic activity compared to fresh fish. Freezing preserved fish quality and reinforced the anti‐thrombotic properties of fish oils, since even after 6 months of freezing, fish oils preserve their nutritional value in terms of protecting against cardiovascular diseases.Practical applications: Fish fillets contain high amount of unsaturated lipids that may easily undergo lipid oxidation. Freezing and frozen storage prevent such oxidative changes so fish quality is retained. Fatty acids and PAF‐antagonists in fish are of major importance since they contribute to the nutritional value of fish. The practical application of this work lies on the evaluation of the nutritional value of fish in terms of cardio protection by examining the impact of freezing on the levels of fatty acids and PAF‐antagonists in aquacultured fish fillets.

Lipid content of frozen fish: Comparison of different extraction methods and variability during freezing storage

In this work, a microwave-assisted extraction (MAE) methodology was compared with several conventional extraction methods (Soxhlet, Bligh & Dyer, modified Bligh & Dyer, Folch, modified Folch, Hara & Radin, Roese-Gottlieb) for quantification of total lipid content of three fish species: horse mackerel (Trachurus trachurus), chub mackerel (Scomber japonicus), and sardine (Sardina pilchardus). The influence of species, extraction method and frozen storage time (varying from fresh to 9months of freezing) on total lipid content was analysed in detail.The efficiencies of methods MAE, Bligh & Dyer, Folch, modified Folch and Hara & Radin were the highest and although they were not statistically different, differences existed in terms of variability, with MAE showing the highest repeatability (CV=0.034). Roese-Gottlieb, Soxhlet, and modified Bligh & Dyer methods were very poor in terms of efficiency as well as repeatability (CV between 0.13 and 0.18).

Low-Intensity Exercise Exerts Beneficial Effects on Plasma Lipids via PPARγ

An important mechanism by which physical activity reduces the risk of cardiovascular disease is through regulating plasma lipids. We investigated whether low-intensity exercise modulates lipid metabolism and the transcription factors peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptor alpha (LXRalpha) responsible for controlling reverse cholesterol transport (RCT). Thirty-four sedentary adults, mean age 45.6 +/- 11.1 yr, participated in an 8-wk low-intensity exercise program consisting of walking 10,000 steps, three times a week. Subjects were randomly allocated to either an exercise group or a sedentary control group, and serum lipid or lipoprotein concentrations were determined. Compared with controls, there was a significant decrease in total cholesterol (preexercise, 5.73 +/- 1.39 mmol x L; postexercise, 5.32 +/- 1.28 mmol x L) and a significant increase in HDL (preexercise, 1.46 +/- 0.47 mmol x L; postexercise, 1.56 +/- 0.50 mmol x L) after the exercise program. There was a significant increase in serum oxidized LDL (oxLDL) concentrations in the exercise group before and after exercise (0 wk, 554 +/- 107 ng x mL; 4 wk, 698 +/- 134 ng x mL; 8 wk, 588 +/- 145 ng x mL). A significant increase in leukocyte mRNA expression for PPARgamma (4 wk, 1.8 +/- 0.9-fold; 8 wk, 4.3 +/- 1.9-fold) was observed, which was reinforced by increased PPARgamma DNA-binding activity postexercise (preexercise, 0.22 +/- 0.09 OD units; postexercise, 1.13 +/- 0.29 OD units). A significant increase in gene expression was observed for the oxLDL scavenger receptor CD36 (4 wk, 3.8 +/- 0.6-fold; 8 wk, 2.7 +/- 0.5-fold) and LXRalpha (8 wk, 3.5 +/- 0.8-fold). Two LXRalpha-regulated genes involved in RCT, namely, ATP-binding cassette transporters A1 and GI (ABCA1 and ABCG1, respectively), were significantly up-regulated postexercise (8 wk: ABCA1, 3.46 +/- 0.56-fold; ABCG1, 3.06 +/- 0.47-fold). We propose that the net effect of these changes may be to increase oxLDL uptake, to stimulate RCT, and thus to promote clearance of proatherogenic lipids from the vasculature, ultimately contributing to the cardiovascular benefits of low-intensity aerobic exercise.

Antigen expression of frozen platelets

Platelet antigens of platelet samples from 36 donors, frozen for different intervals, were evaluated by the platelet suspension immunofluorescence test (PSIFT). A, B, PLA1(HPA-1a) and various HLA antigens were tested by their corresponding antisera. The antigen could be detected in almost all the samples after one month of freezing. After 3 and 6 months, the platelet antigens could only be detected in 29.2% and 3.7% of the samples, respectively. There was no difference in decay of antigen expression among A, B, PLA1 and HLA antigens. When compared with the freshly prepared platelets, frozen platelets presented stronger antigen expression after 2 to 4 weeks of storage. This may suggest that the frozen platelets could be used for platelet crossmatching procedures without loss of their antigenicity within one month.