Seasonal variation in amount of unabsorbed dietary carbohydrate from the intestine after breakfast in Japanese subjects

We previously showed that daytime dim-light exposure has a negative effect on the efficiency of dietary carbohydrate absorption in the evening, whereas evening-time dim-light exposure has a beneficial effect. These results suggest that seasonal changes in the environmental light may affect gastrointestinal activity, and that there might, therefore, be seasonal variation in the efficiency of dietary carbohydrate absorption from the intestine. In order to prove this hypothesis, we measured the amount of dietary carbohydrate unabsorbed from the intestine after a breakfast in healthy female Japanese subjects during the four seasons of the year. We estimated the amount of unabsorbed dietary carbohydrate by the breath hydrogen test, which measures the amount of hydrogen in exhaled air. A 6 g solution of lactosucrose, an indigestible trisaccharide, was used for comparison. Two groups of subjects, 12 subjects in Osaka and 14 subjects in Nagano, were studied in the winter (January to February), spring (April to May), summer (July to August), and autumn (October to November) of 2004. We found the following results: (1) In no season were there any significant differences between the two subgroups in the orocecal transit time of the breakfast and the lactosucrose solution. Nor were there any significant differences in the amount of unabsorbed dietary carbohydrate from the breakfast. (2) Using the pooled data of the total of 26 subjects, there was no significant seasonal variation in the orocecal transit time of the breakfast or the lactosucrose solution. (3) There was a significant seasonal variation in the amount of unabsorbed dietary carbohydrate from the breakfast. (4) The amount of unabsorbed dietary carbohydrate from the breakfast was largest in winter and smallest in autumn. Results in spring and in summer were similar and intermediate between those in winter and autumn. Post hoc multiple comparison tests showed that the amount of unabsorbed dietary carbohydrate in winter was significantly larger than in autumn. (5) In winter, the average ratio of the amount of unabsorbed dietary carbohydrate to the total amount of carbohydrate in the breakfast was about 12%; in autumn it was about 6%. These results clearly show that there is seasonal variation in the efficiency of intestinal dietary carbohydrate absorption among young female Japanese subjects.     

Seasonal Variation in the Amount of Dietary Carbohydrate Not Absorbed from the Intestine after Breakfast in Elderly Japanese Females

It was previously shown that there is seasonality in the amount of dietary carbohydrate not absorbed from the intestine after breakfast, the amount of carbohydrate in winter being significantly larger than that in autumn in young Japanese subjects. In order to investigate this phenomenon further, the experiment was repeated on 22 elderly Japanese female subjects (61–78 yrs of age) during the four seasons of the year. The amount of unabsorbed dietary carbohydrate by the breath hydrogen test, which measures the amount of hydrogen in exhaled air, was then esitmated. A 6 g solution of lactosucrose, an indigestible trisaccharide, was used for comparison. Two groups of subjects, 16 subjects in Osaka and 6 subjects in Nagano, were studied in the summer (July to August) and autumn (October to November) of 2005 and the winter (January to February) and spring (April to May) of 2006. The following results were found using the pooled data of the total of 22 subjects. With regard to the amount of breath hydrogen excretion of the lactosucrose solution, there was no significant difference between the four seasons. There was a significant seasonal change in the efficiency of dietary carbohydrate absorption from the intestine after breakfast. The percentage of total carbohydrate that was not absorbed was lowest in the spring and highest in the winter. A comparison of the results from studies on the elderly and young subjects revealed the percentage of total carbohydrate that was not absorbed in the elderly was significantly lower than in the young in the winter, spring, and summer. These results indicate that there is seasonal variation in the efficiency of dietary carbohydrate absorption from the intestine among elderly female Japanese subjects as well as young female Japanese subjects. They also suggest that the efficiency of dietary carbohydrate absorption from the intestine after breakfast is retained in these naturally active and healthy elderly subjects.     

Seasonal variation in the amount of dietary carbohydrate not absorbed from the intestine after breakfast in elderly Japanese females

It was previously shown that there is seasonality in the amount of dietary carbohydrate not absorbed from the intestine after breakfast, the amount of carbohydrate in winter being significantly larger than that in autumn in young Japanese subjects. In order to investigate this phenomenon further, the experiment was repeated on 22 elderly Japanese female subjects (61-78 yrs of age) during the four seasons of the year. The amount of unabsorbed dietary carbohydrate by the breath hydrogen test, which measures the amount of hydrogen in exhaled air, was then esitmated. A 6 g solution of lactosucrose, an indigestible trisaccharide, was used for comparison. Two groups of subjects, 16 subjects in Osaka and 6 subjects in Nagano, were studied in the summer (July to August) and autumn (October to November) of 2005 and the winter (January to February) and spring (April to May) of 2006. The following results were found using the pooled data of the total of 22 subjects. With regard to the amount of breath hydrogen excretion of the lactosucrose solution, there was no significant difference between the four seasons. There was a significant seasonal change in the efficiency of dietary carbohydrate absorption from the intestine after breakfast. The percentage of total carbohydrate that was not absorbed was lowest in the spring and highest in the winter. A comparison of the results from studies on the elderly and young subjects revealed the percentage of total carbohydrate that was not absorbed in the elderly was significantly lower than in the young in the winter, spring, and summer. These results indicate that there is seasonal variation in the efficiency of dietary carbohydrate absorption from the intestine among elderly female Japanese subjects as well as young female Japanese subjects. They also suggest that the efficiency of dietary carbohydrate absorption from the intestine after breakfast is retained in these naturally active and healthy elderly subjects.     

Seasonal variation in gastric myoelectrical activity in young Japanese females

In order to test our hypothesis that there is seasonal variation in digestion and absorption of dietary carbohydrate from the intestine, we previously determined the amount of unabsorbed carbohydrate after breakfast by the breath hydrogen test in the four seasons. In pursuing our hypothesis further, we also recorded gastric myoelectrical activity before and after the breakfasts. In the current report, we describe the seasonality of gastric myoelectrical activity. Twenty-six Japanese female subjects were studied in winter, spring, summer and autumn. The cutaneous electrogastrogram was analysed by spectral analysis to compute the pre- and post-prandial dominant slow wave frequency (DF), and percentage of the 2 - 4 cpm gastric slow wave (Normal %). Two-factor ANOVA indicated that there was no significant seasonal variation in DF and Normal %. These results indicate that seasonal variations in digestion and absorption of dietary carbohydrate are caused by factors other than gastric and small intestinal motility.     

Effect of post-prandial posture on orocecal transit time and digestion of milk lactose in humans

We examined the effect of post-prandial body posture on orocecal transit time and absorption of milk lactose using the breath hydrogen test. In this experiment, subjects ingested a cup of commercially available milk to which we had added a small amount of lactosucrose (an indigestible trisaccharide), and then they lay on their backs or sat on a chair for the first 4 hr (from 08:00 to 12:00). After four hours lying or sitting, they remained sedentary on a sofa for the second six hr (from 12:00 to 18:00). Participants' end alveolar breath samples were collected every 15 min from 08:00 to 12:30, then every 30 min from 13:00 to 18:00. The experiment was conducted on two consecutive days using a randomized, crossover study design. Examination showed that the orocecal transit time of the oligosaccharides (lactosucrose and milk lactose) under the post-prandial supine condition was significantly longer than that under the sitting condition. In addition, the amount of breath hydrogen excretion under the supine condition was significantly lower than under the sitting condition, indicating that the unabsorbed milk lactose moved into cecum under the supine condition is smaller than that under the sitting condition. These findings provide evidence that postprandial supine posture works more beneficially to digest and absorb milk lactose when compared to the sitting posture.     

Effects of a late supper on digestion and the absorption of dietary carbohydrates in the following morning

Background

Our previous experiment showed that the light intensity exposed on the subjects during evening time had no effect in the following morning on the efficiency of the digestion and absorption of dietary carbohydrates ingested at a usual suppertime. People who keep late hours usually have a late suppertime; thus, we examined the effects of a late suppertime on gastrointestinal activity in the following morning in comparison to that of a usual suppertime.

Methods

Twelve female university students volunteered as paid participants. The breath hydrogen test was carried out to estimate the amount of unabsorbed dietary carbohydrates and the percentage of the total amount of dietary carbohydrates in the breakfast that were unabsorbed, as well as to estimate oro-cecal transit time. The respiratory quotient was also measured to find the ratio of carbohydrates/lipid metabolism in the post-breakfast state. Subjects’ peripheral blood glucose concentration was measured by a blood glucose meter. The subjects participated under two different experimental conditions: with a usual suppertime (having supper at 18:00) and a late suppertime (having supper at 23:00).

Results

The efficiency of the digestion and absorption of dietary carbohydrates in the breakfast under late suppertime conditions was higher than that under usual suppertime conditions. Usual or late suppertime had no effect on the ratio of carbohydrates to lipids oxidized after the subjects had breakfast. There were significant differences in the blood glucose level between the two conditions at 30, 60, 120, 150, and 180 minutes after having breakfast, whereas the mean blood glucose level under late suppertime conditions was significantly higher than under usual suppertime conditions.

Conclusions

Having a late supper showed a worse effect on postprandial serum glucose profiles the following morning. This study confirmed that keeping our usual meal timing is important for our health.     

Comparison of carbohydrate digestion between Japanese and Polish healthy subjects

We have revealed that light environment affects digestion and absorption of dietary carbohydrates in the gastrointestinal tract. This experimental result supposes that the efficiency of carbohydrate absorption may differ among people who live in different latitudes, such as Japanese and Polish people, at the same calendar season. In order to prove this hypothesis, we have been comparing the efficiency of carbohydrate absorption using the breath hydrogen test in Japan and Poland. Here, we report the comparison of the result obtained in the summer of 2004 as the following; (1) Orocecal transit time (OCTT) for indigestible trisaccharide of Japanese subjects was significantly longer than that in Poland (p = 0.043). (2) On the ingestion of minestrone, the amount of unabsorbed carbohydrate of Japanese subjects (which was estimated as trisaccharide equivalent) was significantly larger than that of Polish subjects (p = 0.006).     

Effect of Evening Exposure to Dim or Bright Light on the Digestion of Carbohydrate in the Supper Meal

In a previous study we found that daytime exposure to bright as compared to dim light exerted a beneficial effect on the digestion of the evening meal. This finding prompted us to examine whether the digestion of the evening meal is also affected by evening light intensity. Subjects lived in light of 200 lux during the daytime (08:00–17:00 h) and took their evening meal at 17:00 h under 20 lux (evening dim‐light condition: 17:00–02:00 h) or 2000 lux (evening bright‐light condition: 17:00–02:00 h) until retiring at 02:00 h. Assessment of carbohydrate digestion of the evening meal was accomplished by a breath hydrogen test that is indicative of the malabsorption of dietary carbohydrate. Hydrogen excretion in the breath in the evening under the dim‐light condition was significantly less than under the bright‐light condition (p < 0.05). This finding is the opposite to that obtained in previous experiments in which subjects were exposed to the different intensities of light during the daytime, and indicates that the exposure to dim light in the evening exerts a better effect on carbohydrate digestion in the evening meal than does the exposure to bright light.     

Effect of postprandial posture on digestion and absorption of dietary carbohydrate

The effect of postprandial body posture on digestion and absorption of dietary carbohydrate were examined through breath hydrogen test on 6 female subjects. During the experiment, the participants either sat on a chair or lay on their backs for the first 4 hr (from 08:00 to 12:00) after eating the test breakfast meal. They then remained sedentary on a sofa for 6 hr (12:00 to 18:00). Participants' end alveolar breath samples were collected for 10 hr (every 15 min from 08:00 to 12:30, and then every 30 min until 18:00). The experiment was conducted on two consecutive days using a randomized, crossover study design. The results demonstrated that in the supine position orocecal transit time of the test meal was significantly slower than in the sitting position (260 +/- 21 min and 238 +/- 20 min, respectively, p < 0.01). In addition, afternoon breath hydrogen excretion due to a partial malabsorption of dietary carbohydrate and its fermentation in the colon was significantly larger in the sitting position (144.0 +/- 24.1 ppm.hr) than in the supine position (110.0 +/- 26.1 ppm.hr, p < 0.05). These results support the hypothesis that there was a marked effect of postprandial body posture on the function of the digestive system. The present findings suggest that the postprandial supine position is preferable to the sitting position for the digestion and absorption of dietary carbohydrate.     

Effect of evening exposure to dim or bright light on the digestion of carbohydrate in the supper meal

In a previous study we found that daytime exposure to bright as compared to dim light exerted a beneficial effect on the digestion of the evening meal. This finding prompted us to examine whether the digestion of the evening meal is also affected by evening light intensity. Subjects lived in light of 200 lux during the daytime (08:00-17:00 h) and took their evening meal at 17:00 h under 20 lux (evening dim-light condition: 17:00-02:00 h) or 2000 lux (evening bright-light condition: 17:00-02:00 h) until retiring at 02:00 h. Assessment of carbohydrate digestion of the evening meal was accomplished by a breath hydrogen test that is indicative of the malabsorption of dietary carbohydrate. Hydrogen excretion in the breath in the evening under the dim-light condition was significantly less than under the bright-light condition (p < 0.05). This finding is the opposite to that obtained in previous experiments in which subjects were exposed to the different intensities of light during the daytime, and indicates that the exposure to dim light in the evening exerts a better effect on carbohydrate digestion in the evening meal than does the exposure to bright light.     

Comparison of seasonal variation in the fasting respiratory quotient of young Japanese, Polish and Thai women in relation to seasonal change in their percent body fat

Background

From the viewpoint of human physiological adaptability, we previously investigated seasonal variation in the amount of unabsorbed dietary carbohydrates from the intestine after breakfast in Japanese, Polish and Thai participants. In this investigation we found that there were significant seasonal variations in the amount of unabsorbed dietary carbohydrates in Japanese and Polish participants, while we could not find significant seasonal variation in Thai participants. These facts prompted us to examine seasonal variations in the respiratory quotient after an overnight fast (an indicator of the ratio of carbohydrate and fat oxidized after the last meal) with female university students living in Osaka (Japan), Poznan (Poland) and Chiang Mai (Thailand).

Methods

We enrolled 30, 33 and 32 paid participants in Japan, Poland and Thailand, respectively, and measurements were taken over the course of one full year. Fasting respiratory quotient was measured with the participants in their postabsorptive state (after 12 hours or more fasting before respiratory quotient measurement). Respiratory quotient measurements were carried out by means of indirect calorimetry using the mixing chamber method. The percent body fat was measured using an electric bioelectrical impedance analysis scale. Food intake of the participants in Osaka and Poznan were carried out by the Food Frequency Questionnaire method.

Results

There were different seasonal variations in the fasting respiratory quotient values in the three different populations; with a significant seasonal variation in the fasting respiratory quotient values in Japanese participants, while those in Polish and Thai participants were non-significant. We found that there were significant seasonal changes in the percent body fat in the three populations but we could not find any significant correlation between the fasting respiratory quotient values and the percent body fat.

Conclusions

There were different seasonal variations in the fasting respiratory quotient values in the three different populations. There were significant seasonal changes in the percent body fat in the three populations but no significant correlation between the fasting respiratory quotient values and the percent body fat.     

Everyday breath hydrogen excretion profile in Japanese young female students

A breath hydrogen test has been used widely as a noninvasive and simple method of detecting carbohydrate malabsorption as well as estimation of the small intestinal and orocecal transit time. By means of this method, we have examined the change in breath hydrogen concentration of young female students in their everyday life in order to reveal the breath hydrogen excretion profile under normal circumstances. In this survey, we have asked them to collect their own breath samples every one-hour as regularly as possible during one day from awakening until bedtime. We also asked them to complete the questionnaire concerning their dietary habit, dietary record and physical activities. Among the 43 subjects who gave the breath hydrogen records, 37 subjects excreted detectable hydrogen into their alveolar air. By comparing the changes in breath hydrogen concentration during the time of day, breath hydrogen excretions could be classified into two distinct patterns; more than half of the total hydrogen excretion occurred in the first half of the waking hours (designated as "pattern A", 18 cases) and in the latter half (designated as "pattern B", 19 cases). Taking into consideration the subjects' records of diets and physical activities, the early-pronounced breath hydrogen excretion observed among 18 "pattern A" students was probably resulted from the malabsorption of the dietary carbohydrate in the breakfast meals.     

Gastric secretion,motility, and emptying in hyperkinesia

A study performed with healthy males differing in motor activity (athletes and nonathletes) revealed that, in subjects adapted to physical loads, fluid gastric secretion and the gastrointestinal motor and emptying functions were stable and did not change considerably under the influence of physical exercise. The orocecal transit time of a test breakfast depended on the level and the character of individual everyday motor activity. When a physical load was combined with a carbohydrate breakfast, parameters of gastrointestinal motility and emptying changed in parallel with blood levels of insulin, the somatotropic and adrenocorticotropic hormones, triiodothyronine, and cyclic guanosine monophosphate.Translated from Fiziologiya Cheloveka, Vol. 31, No. 1, 2005, pp. 120–129.Original Russian Text Copyright © 2005 by Rechkalov.     

Effects of skin pressure by clothing on digestion and orocecal transit time of food

In order to reveal the influence of clothing skin pressure on digestion of food through the gastrointestinal tract, we examined the absorption of dietary carbohydrate and orocecal transit time of a test meal by means of a breath hydrogen test on 7 healthy young women. In this experiment, we collected breath samples from the participants wearing loose-fitting experimental garment on the second day of the experiment and from the same participants but wearing an additional tight-fitting girdle on the following day for 16 hours and 9 hours, respectively. Skin pressure applied by a girdle on participant's waist, abdomen and hip region was 15.5 +/- 0.4 mmHg (mean +/- SE), 11.0 +/- 0.2 mmHg, and 13.6 +/- 0.6 mmHg, respectively, and the values were 2-3 times larger than those of the experimental garment. The hydrogen concentration vs. time curve showed that breath hydrogen levels at its peaks (15:00, 15:30, 16:00, 16:30, and 17:00 hr) on the third day of the experiment were significantly higher than those of the corresponding time on the second day (p < 0.05 at 17:00 and 15:00, p < 0.01 at 15:00, 16:00 and 16:30). Consequently, significantly pronounced breath hydrogen excretion was observed under the "pressure" clothing condition (p < 0.01). On the other hand, the transit time of the test meal for the subjects wearing a girdle did not differ significantly from that for the subjects wearing the garment of less pressure (270 +/- 18 minutes and 263 +/- 21 minutes, respectively). These results indicate that the clothing skin pressure has an inhibitory effect on the absorption of dietary carbohydrate in the small intestine, but no effect on the orocecal transit time of a meal.     

Seasonal influences on carbohydrate metabolism in the CAM bromeliad Aechmea ��Maya��: consequences for carbohydrate partitioning and growth

Background and Aims

Photosynthetic plasticity in response to a range of environmental factors that include [CO₂], water availability, light intensity and temperature, is ubiquitous among plants with crassulacean acid metabolism (CAM). The present study examined how seasonal changes in light availability, as experienced by greenhouse CAM crops in northern latitude regions, influence diel carboxylation patterns and impact on carbon gain and seasonal accumulation of biomass.

Methods

In the CAM bromeliad Aechmea ‘Maya’ integrated measurements of leaf gas exchange, diel metabolite dynamics (e.g. malate, soluble sugars and starch) and biomass accumulation were made four times a year, i.e. in winter, spring, summer and autumn.

Key Results

During the brighter seasons (spring and summer) daytime Phases II and IV were dominated by C₄ carboxylation, whilst the higher diurnal uptake in the autumn and winter was characterized by equal contributions of both Rubisco and PEPC. As a consequence, net CO₂ uptake showed a significant depression at the end of the day in the darker months when supplementary illumination was turned off. Remarkable seasonal consistency was found in the amount of storage reserves available for nocturnal carboxylation, a consequence of predominantly daytime export of carbohydrate in spring and summer whilst nocturnal export was the major sink for carbohydrate in autumn and winter.

Conclusions

Throughout the different seasons Aechmea ‘Maya’ showed considerable plasticity in the timing and magnitude of C₃ and C₄ carboxylation processes over the diel cycle. Under low PPFD (i.e. winter and autumn) it appears that there was a constraint on the amount of carbohydrate exported during the day in order to maintain a consistent pool of transient carbohydrate reserves. This gave remarkable seasonal consistency in the amount of storage reserves available at night, thereby optimizing biomass gain throughout the year. The data have important practical consequences for horticultural productivity of CAM plants and suggest a scenario for reconciling carbohydrate partitioning between competing sinks of nocturnal acidification and export for growth.Key words: Aechmea ‘Maya’, seasonal, CAM, bromeliad, carbon budgets, gas exchange, metabolite dynamics, PEPC, photoperiod extension, PPFD, photosynthetic plasticity, Rubisco     

Effects of dim or bright-light exposure during the daytime on human gastrointestinal activity

On the basis of our previous findings that bright-light exposure during the daytime has profound influence on physiological parameters such as melatonin secretion and tympanic temperature in humans, we proposed the hypothesis that bright vs. dim light-exposure during the daytime has a different influence on the activity of the digestive system via the endocrine and/or autonomic nervous system. To examine this hypothesis, we conducted a series of counterbalanced experiments in which subjects stayed the daytime (7:00 to 15:00h) under either a dim (80 lux) or bright (5,000 lux) light condition. We measured gastrointestinal activity using a breath hydrogen (indicative of carbohydrate malabsorption) and an electrogastrography (EGG, indicative of gastric myoelectric activity) test. The results showed the postprandial breath hydrogen excretion during the following nighttime period after daytime exposure to the dim-light condition was significantly higher than under the bright-light condition (p < 0.05). In addition, the spectrum total power of the EGG recorded after taking the evening meal was significantly lower for the dim than bright-light condition (p < 0.05). These results support our hypothesis and indicate that dim-light exposure during the daytime suppresses the digestion of the evening meal, resulting in malabsorption of dietary carbohydrates in it.     

EVENING DAYLIGHT MAY CAUSE ADOLESCENTS TO SLEEP LESS IN SPRING THAN IN WINTER

Sleep restriction commonly experienced by adolescents can stem from a slower increase in sleep pressure by the homeostatic processes and from phase delays of the circadian system. With regard to the latter potential cause, the authors hypothesized that because there is more natural evening light during the spring than winter, a sample of adolescent students would be more phase delayed in spring than in winter, would have later sleep onset times, and because of fixed school schedules would have shorter sleep durations. Sixteen eighth-grade subjects were recruited for the study. The authors collected sleep logs and saliva samples to determine their dim light melatonin onset (DLMO), a well-established circadian marker. Actual circadian light exposures experienced by a subset of 12 subjects over the course of 7 days in winter and in spring using a personal, head-worn, circadian light measurement device are also reported here. Results showed that this sample of adolescents was exposed to significantly more circadian light in spring than in winter, especially during the evening hours when light exposure would likely delay circadian phase. Consistent with the light data, DLMO and sleep onset times were significantly more delayed, and sleep durations were significantly shorter in spring than in winter. The present ecological study of light, circadian phase, and self-reported sleep suggests that greater access to evening daylight in the spring may lead to sleep restriction in adolescents while attending school. Therefore, lighting schemes that reduce evening light in the spring may encourage longer sleep times in adolescents. (Author correspondence: figuem@rpi.edu)     

Salivary Secretion under the Influence of Bright/Dim Light Exposure in the Morning and Evening in Humans

Recent studies show that bright and dim light intensities during the daytime have important regulatory functions. Our present study was performed to evaluate the effect of exposure to different light intensities during the morning and evening on salivary secretion and its sodium concentration. The study involved 6 healthy, female volunteers who were exposed to dim light (100 lx) from 7:00 to 17:00 and to bright light (3000 lx) from 17:00 to 23:00 one day, and to bright light (3000 lx) from 7:00 to 17:00 and dim light (100 lx) from 17:00 to 23:00 on the next day. We collected salivary samples every 10 minutes during 2 hours in the morning and in the evening by means of a Lashley cup. Saliva secretion was stimulated by sweet candy. The amount of saliva secreted was significantly greater in the morning under bright light exposure, while it was significantly greater in the evening under dim light exposure. We discuss these findings in terms of changes in activity of the parasympathetic nervous system (PNS) and sympathetic (SNS) nervous system produced by exposure to different light intensities at different times of the day.     

Quantification of cholesterol absorption in man by fecal analysis after the feeding of a single isotope-labeled meal

The fecal excretion of cholesterol-4-(14)C and -sitosterol-22,23-(3)H has been studied in normal human subjects after they had ingested a single meal containing the radioactive substances. When 150 mg of -sitosterol, dispersed in the butter of a standard breakfast, was fed to 20 subjects the mean recovery of isotope in the feces was 90%. When plant sterols (70% -sitosterol, 30% campesterol) were fed together with cholesterol and used as an internal standard to correct for losses of cholesterol during intestinal transit and analytical procedures, excretion of dietary cholesterol was found to be 60-80%, irrespective of the amount fed over the range 150-1910 mg. If absorption of cholesterol is calculated from these figures, no saturation of the cholesterol absorption mechanism is indicated for the amounts of cholesterol fed in this investigation. The reason for the differences between these findings and those previously reported by other procedures is not clear, but may be related to the acute administration of a single dose of cholesterol in this study.     

Seasonal variation in haematological parameters in male and female Tinca tinca

This study was designed to investigate any seasonal (spring, summer, autumn and winter) changes in haematological parameters in the blood of Tinca tinca measuring the number of red blood cells (RBC), haematocrit, white blood cells, and total plasma proteins.The results show significant changes in RBC and haematocrit in males comparing spring and summer with autumn and winter, whereas in females the RBC remained constant for all 4 seasons but the haematocrit decreased in autumn and winter compared to spring and summer. The white blood cells of male and female animals were significantly lower in spring and winter compared to summer and autumn. In male fish total protein contents significantly decreased in autumn and winter compared to spring and summer, whereas in females protein output significantly decreased in winter compared to the other seasons. The results indicate marked seasonal variation in the blood of male and female Tinca tinca. This variation may play a important protective role for the survival of the animals.