Recalling sweet taste intensities in the presence and absence of other tastes

Memory for sweet taste intensities in different media during 125 h was investigated using three concentrations (w/w) of sucrose: 4.21% (0.125 M), 8.28% (0.25 M) and 16.06% (0.5 M). Sucrose was dissolved in four media [water with no tastant and water with 0.73% (0.125 M) sodium chloride, 0.04% (0.002 M) citric acid and 0.04% (0.002 M) caffeine] as standard stimuli. Subjects (n = 39) were assigned into four groups, each group performing the memory task in one medium only. After tasting each standard the subjects reproduced the subjective taste intensity immediately and after 12 min and 1, 5, 25 and 125 h by mixing portions of low (0%) and high (29.75%; 1 M) concentrations (w/w) of sucrose and by tasting and retasting (ad libitum procedure). The produced sucrose concentrations increased significantly from the first session to the 125 h time interval. There was a significant difference between immediately reproduced standard concentrations and concentrations produced after all time intervals. Relative differences from standard (delta i/i) differed only between concentrations produced immediately and after 125 h time interval. The low (4.21%) concentration showed larger differences from standard than the high (16.06%) concentration. The added tastant had no effect on the results.      

Influences of feedback and ascending and descending trial presentations on perithreshold odor detection performance

The influences of feedback and ascending and descending trial sequences on the ability of 135 college-aged subjects to detect phenyl ethyl alcohol odorant concentrations ranging from 10(-9) to 10(-5.5) v/v were examined in a two-alternative forced-choice test paradigm. At the highest concentrations, ascending trial sequences produced better performance than descending trial sequences; the reverse was true at the lowest concentrations. There was a tendency for feedback to improve performance marginally at the lowest two odorant concentrations presented. In the region associated with a traditional detection threshold calculation (i.e. at the 75% performance point in a two-choice detection task), no influences of feedback or direction of trial sequence were apparent. These data indicate that the effects of explicit feedback and trial sequence direction depend upon the segment of the peri-threshold stimulus concentration continuum evaluated.     

Stair Descending Exercise Using a Novel Automatic Escalator: Effects on Muscle Performance and Health-Related Parameters

A novel automatic escalator was designed, constructed and used in the present investigation. The aim of the present investigation was to compare the effect of two repeated sessions of stair descending versus stair ascending exercise on muscle performance and health-related parameters in young healthy men. Twenty males participated and were randomly divided into two equal-sized groups: a stair descending group (muscle-damaging group) and a stair ascending group (non-muscle-damaging group). Each group performed two sessions of stair descending or stair ascending exercise on the automatic escalator while a three week period was elapsed between the two exercise sessions. Indices of muscle function, insulin sensitivity, blood lipid profile and redox status were assessed before and immediately after, as well as at day 2 and day 4 after both exercise sessions. It was found that the first bout of stair descending exercise caused muscle damage, induced insulin resistance and oxidative stress as well as affected positively blood lipid profile. However, after the second bout of stair descending exercise the alterations in all parameters were diminished or abolished. On the other hand, the stair ascending exercise induced only minor effects on muscle function and health-related parameters after both exercise bouts. The results of the present investigation indicate that stair descending exercise seems to be a promising way of exercise that can provoke positive effects on blood lipid profile and antioxidant status.     

Pancreatic response to bolus injection of cholecystokinin-pancreozymin in anaesthetized and conscious rats fed raw soyaflour

Pancreatic secretion was studied in rats fed raw soyafour before (basal) and after stimulation with cholecystokinin-pancreozymin (CCK) given in either ascending or descending dose orders ranging from 1.25 to 20 or from 20 to 1.25 Crick-Harper-Raper units (CHRU). These results were compared with those reported previously for animals fed a stock cube diet. Two experimental conditions were used: anaesthetized animals were tested immediately after cannulation of the pancreatic duct and conscious animals were tested 48 h after surgery. Basal flow was significantly increased in anaesthetized and conscious rats fed RSF compared with the respective animals fed cubes. Mean basal protein output was also increased, but this difference was not significant. The pancreatic response to the ascending and descending doses of CCK in anaesthetized rats fed RSF was linearly related to the log of the dose of CCK in both animals fed RSF and cubes, though the response to CCK was greater in the rats fed RSF. When ascending doses of CCK were given to conscious rats fed RSF, the protein output increased up to 10 CHRU of CCK but was inhibited by 20 CHRU of CCK, whereas it decreased after the first dose of CCK (1.25 CHRU) in animals fed cubes. When descending doses of CCK were given to animals fed RSF, protein output was greatest after the first dose and no simple relationship between dose and response was seen. Compared with rats fed cubes, the pancreas in rats fed RSF thus appears to respond to a given dose of CCK with increased secretion, and conscious animals fed RSF can tolerate a higher dose of CCK before protein output is inhibited. This is consistent with an increased population of acinar cells in the animals fed RSF, with each hypertrophied cell responding to CCK with increased secretion.     

Adaptation level effects in discrimination of flicker frequency

Pigeons accustomed to food reinforcement for responding in the presence of a 25-Hz flickering light were exposed to several sets of flicker-frequency stimuli arranged as increasing and decreasing series. In the first experiment, food was occasionally delivered for key pecks during 30-s periods of 25-Hz flicker appearing at the beginning, midway, and at the end of an ascending and descending series of nine frequencies, ranging from 13 to 37 Hz. These stimuli appeared for 15-s periods with no food available (extinction). Gradients of responding to flicker values in the ascending series differed from those in the descending series, showing displacements in peak responding toward the lower and higher frequency values, respectively. The same effects occurred when the sequence was changed so that a descending series was followed by an ascending series of frequencies. These effects are consonant with an adaptation level (AL) interpretation and were replicated in a second experiment in which durations of the extinction presentations were increased to 30s. In a final condition, only a descending series was presented and displacement of peak responding from 25 Hz to a higher frequency stimulus, 28 Hz, was observed.     

Sensitization of rat gastrointestinal tract to acetylcholine and histamine produced by X-radiation

Abdominal x-radiation produces both acute and chronic disturbances of gastrointestinal motility. Anaesthetized Albino-Oxford rats received one-session x-radiation (absorbed dose 10 Gy) of whole abdomen. Two hours after irradiation the rats were sacrificed and segments of their gastrointestinal tract (gastric fundus, jejunum, ileum and ascending colon, were mounted in isolated organ bath. Acetylcholine and 5-hydroxytryptamine produced tonic contractions of all gut segments, while histamine did so only with gastric fundus. While contractile effect of 5-hydroxytryptamine was not affected by x-radiation, the responses of all gut segments on acetylcholine were potentiated and shifted towards lower concentrations. After x-radiation histamine produced concentration-dependent tonic contraction of previously unresponsive jejunum and ascending colon. The results of our study suggest that x-radiation produces acute sensitization of rat gastrointestinal tract to acetylcholine and histamine.     

Temporal interrelationships at 15-min intervals among oxytocin, LH, and progesterone during a pulse of a prostaglandin F2α metabolite in heifers

A pulse of a PGF2α metabolite (PGFM) was induced by treatment with 0.1 mg of estradiol-17β on Day 15 (Day 0=ovulation; n=9 heifers). Blood samples were taken every 15 min for 9h beginning at treatment (Hour 0). For PGFM and LH, an intraassay-CV method was used to detect fluctuations in the 15-min samples and pulses in the hourly samples. A mean of 6.9 ± 0.4 PGFM fluctuations/9 h were superimposed on the hourly PGFM concentrations, compared to 2.1 ± 0.5 LH fluctuations/9 h (P<0.02). An increase (P<0.02) in oxytocin began 15 min before the beginning nadir of the PGFM pulse. A transient increase in progesterone did not occur at the beginning nadir of the PGFM pulse. Progesterone decreased (P<0.02) during the ascending portion and increased (P<0.03) as a rebound during the descending portion of the PGFM pulse. The peak of an LH pulse occurred 1.5 ± 0.4 h (range, 0.25-2.75 h) after the peak of the PGFM pulse. The wide range in the interval from a PGFM peak to an LH peak obscured the contribution of increasing LH to the rebound. The results did not support the hypothesis that oxytocin and PGFM increase concurrently. Results supported the hypothesis that the immediate transient progesterone increase that has been demonstrated with exogenous PGF2α does not occur during the ascending portion of an endogenous PGFM pulse. The hypothesis that the progesterone rebound after the peak of a PGFM pulse is temporally related to an LH pulse was supported.     

A possible correlation between ultrastructure and function in the thin descending and ascending limbs of the loop of Henle of rabbit kidney

Summary An ultrastructural study of the thin loops of Henle has been made in the renal papilla of the rabbit. Animals in different states of water balance were used but no morphological difference was observed in the loops obtained from animals in different experimental groupings. The cytoplasm of the squamous cells lining the limbs was characterised by a paucity of organelles. Descending and ascending limbs were distinguishable. A distinct morphological difference was seen in the junctional regions of cell processes of the descending and ascending thin limbs of the loop. The ascending limb processes were joined by continuous tight junctions whereas the descending limb junctional regions invariably showed a space of at least 70 Å between adjacent processes. It is suggested that there may be a correlation between the structure of these junctional regions and the different permeability characteristics of the two limbs. The thin ascending limb must, on physiological evidence, be relatively impermeable with reference to the thin descending limb.The author wishes to thank Professor F. R. Johnson for his advice and assistance, and Mr. R. F. Birchenough, Mr. P. L. Hyam and Mr. J. Manston for valuable technical assistance.     

Insights into mechanisms of intestinal segmentation in guinea pigs: a combined computational modeling and in vitro study

Segmentation in the guinea pig small intestine consists of a number of discrete motor patterns including rhythmic stationary contractions that occur episodically at specific locations along the intestine. The enteric nervous system regulates segmentation, but the exact circuit is unknown. Using simple computer models, we investigated possible circuits. Our computational model simulated the mean neuron firing rate in the feedforward ascending and descending reflex pathways. A stimulus-evoked pacemaker was located in the afferent pathway or in a feedforward pathway. Output of the feedforward pathways was fed into a simple model to determine the response of the muscle. Predictions were verified in vitro by using guinea pig jejunum, in which segmentation was induced with luminal fatty acid. In the computational model, local stimuli produced an oral contraction and anal dilation, similar to in vitro responses to local distension, but did not produce segmentation. When the stimulus was distributed, representing a nutrient load, the result was either a tonic response or globally synchronized oscillations. However, when we introduced local variations in synaptic coupling, stationary contractions occurred around these locations. This predicts that severing the ascending and descending pathways will induce stationary contractions. An acute lesion in our in vitro model significantly increased the number of stationary contractions immediately oral and anal to the lesion. Our results suggest that spatially localized rhythmic contractions arise from a local imbalance between ascending excitatory and descending inhibitory muscle inputs and require a distributed stimulus and a rhythm generator in the afferent pathway.     

Parameters of delay discounting assessment: number of trials, effort, and sequential effects.

Procedural variants in estimating delay discounting (DD) have been shown to yield significant within-subject differences in estimated degree of delay discounting as well as variations in the patterns of choice. The purpose of this study was to evaluate the effect of subject control over the number of trials in a delay discounting task, on degree of delay discounting. Participants were assessed with two computerized DD assessments: the full-length method presented participants with a fixed set of 240 trials, and the abbreviated task, where once participants had shown indifference between the immediate and delayed rewards, the remaining trials for that delay value were omitted. While the full-length and abbreviated methods did not differentially affect patterns of choice or estimated delay discounting, the order of presentation (ascending or descending) of immediate rewards produced differences in each measure: rate of delay discounting was significantly lower when estimated with the descending sequence; a larger proportion of area under the discounting curve was concentrated around the indifference point trial with the descending sequence; and a lower correlation was observed between estimates obtained across methods with the descending sequence.     

Monitoring Powder Blend Homogeneity Using Light-Induced Fluorescence

Light-induced fluorescence (LIF) was evaluated as a process analytical technology to monitor blend homogeneity and establish a relationship with high-performance liquid chromatography (HPLC). Secondary aims for this study included a determination of blend steady-state, acceptable mixing time interval, and mixing end point. Also, identification of potential “dead spots” in the 124 L intermediate bulk container mixing tote was explored. Individual samples from 13 sample locations were collected at 0.25, 0.5, 0.75, 1, 2, 5, 10, and 20 min and analyzed using LIF and HPLC. LIF and HPLC methods showed similar mixing profiles. A coefficient of determination (R ²) of 0.86 (p value < 0.0001) was obtained for a second-degree polynomial bivariate fit of LIF counts by HPLC percent label claim (%LC). A significant linear relationship was determined between LIF percent relative standard (%RSD) and HPLC %RSD (R ² = 0.97, p < 0.0001). The LIF steady-state, acceptable mixing time interval, and mixing end point were determined to be 1–20, 2–20, and 2 min, respectively. The steady-state, acceptable mixing time interval, and mixing end point determined by HPLC were 1–20, 5–10, and 5 min, respectively. The Tukey–Kramer honestly significant difference analysis of HPLC %LC by sample location at 5 and 10 min mixing times showed that there was a statistical difference between the HPLC %LC group means at two blender locations.     

Effect of cardiogenic gas mixing on arterial O2 and CO2 tensions during breath holding

To examine the effect of cardiogenic gas mixing on gas exchange we measured arterial tension of O2 (PaO2) and arterial tension of CO2 (PaCO2) during 3- to 5-min breath holds (BH) before and after infusing 50 ml of saline into the pericardial space (PCF) of seven anesthetized, paralyzed, mechanically ventilated dogs. During BH the ventilator was disconnected and a bias flow of 50% O2 at 4-5 l/min was delivered through the side ports of a small catheter whose tip was positioned 1 cm cephalad of the carina. Paired runs, alternately with and without PCF, were performed in triplicate in each dog. Initial PaO2 was similar for control runs [81 +/- 3 mmHg (SE)] and PCF runs (78 +/- 3 mmHg; P greater than 0.1). After 3-min BH, PaO2 in PCF runs (33 +/- 3 mmHg) was less than that in control runs (58 +/- 4 mmHg) (P less than 0.001). In contrast, the pattern of PaCO2 during BH did not differ with PCF. After 3-min BH, PaCO2 was 49 +/- 3 mmHg with PCF and 49 +/- 2 mmHg in the control runs (P greater than 0.7). In two dogs, repeated 50-ml reductions in lung volume, produced by rib cage compression, did not alter the time course of PaO2 during BH. Although cardiac output decreased slightly with PCF, hemodynamic changes due to PCF were unlikely to account for the observed fall in PaO2. Our results indicate a substantial effect of cardiogenic gas mixing on O2 uptake when tracheal gas is O2 enriched during breath holding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sex differences in lactate and glycerol levels during maximal aerobic and anaerobic running

Lactate, glycerol, adrenaline, and noradrenaline in venous blood following 400 m and 3000 m runs were measured in 6 untrained male students, 5 female handball players, 6 female sprinters and 6 female long-distance runners. Physical performance in the two events by the untrained males was the same as for the female handball players, but was less than that by the female sprinters and female long-distance runners. Peak blood lactate levels obtained after 400 m sprinting, and glycerol concentration following the 3000 m run were not significantly different between the untrained males and the female handball players. On the other hand, both peak blood lactate concentrations after 400 m sprinting for female sprinters and peak blood glycerol levels following a 3000 m run for female long-distance runners were significantly higher than those in the untrained male subjects. In both runs there was no significant difference in adrenaline and noradrenaline between the untrained male group and the female handball players. These results suggest that blood lactate in a 400 m run, and glycerol in a 3000 m run might be a reflection of physical performance level but not of sex difference.     

心肌带收缩率与急性心肌梗死患者左心室收缩功能关系

目的:急性前壁心肌梗死明显影响室间隔收缩率和左心室射血分数(left ventricular ejection fraction LVEF)。本文旨在探讨心肌带降段及升段收缩率与急性前壁心肌梗死患者LVEF的相关性。方法:收集2015年4月-2017年2月在心内科住院的急性前壁心肌梗死患者36例,正常对照组患者39例。所有患者取左心室长轴M型超声心动图,测量室间隔收缩率、升段收缩率及降段收缩率。心肌梗死左心室射血分数采用双平面Simpson's法计算。结果:与正常对照组相比,心肌梗死组患者舒张末期心肌带升段厚度没有统计学差异(P=0.69),收缩末期升段厚度(P=0.014)更薄、升段收缩率(P0.01)明显降低;心肌梗死组舒张末期降段厚度(P0.01)更薄、收缩末期降段厚度(P0.01)更薄、降段收缩率(P0.01)明显降低;心肌梗死组左心室射血分数与降段收缩率(r~2=0.13,P=0.026)、室间隔增厚率(r~2=0.19,P0.01)呈正相关,与升段收缩率没有相关性(P0.05)。正常对照组左心室射血分数与室间隔增厚率、降段增厚率及升段增厚率无相关性。经过相关分析,筛选出与心肌梗死LVEF的相关因素,进一步经逐步回归分析,得多元线性回归方程为LVEF=48.206+18.914*LVDD(cm)-25.414*LVSD(cm)。结论:急性前壁心肌梗死室间隔降段收缩率明显受损,与左心室射血分数降低有关。多元线性回归方程可估算前壁心肌梗死LVEF。     

Experimental determination of sarcomere force–length relationship in type-I human skeletal muscle fibers

The objectives of this study were to measure the active and passive force–length (F–L) relationships in type-I human single muscle fibers and to compare the results to predictions from the sliding filament model (the “standard model”). We measured isometric forces in chemically skinned fibers at different sarcomere lengths (SLs) in separate maximal activations. The experimental tolerance interval for optimal SL was calculated to be (2.37, 2.95 μm), which included the prediction by the standard model (2.64, 2.81 μm). Average passive slack length was 2.22±0.08 μm, and the passive F–L relationship was well described by an exponential function. Best fit lines were used to estimate the ascending and descending limbs from the active F–L data using the average SL obtained from a digital image of the fiber. The experimental descending limb was also estimated using the shortest SL to address the possible effects of sarcomere inhomogeneity (SI). The experimental slopes of the ascending and descending limbs, 0.42 F_o/μm and ?0.52 F_o/μm (vs. ?0.55 F_o/μm with the shortest SL) respectively, F_o being the maximal isometric force, were significantly less in magnitude than those from the standard model. These results suggested that the difference between experimental and standard models was not fully explained by SI and other factors could be important. The broader experimental F–L curve compared to the standard model implies that human muscle has functionally a wider operating length range where its force-generating capacity is not compromised.     

Pancreatic response of anaesthetized and conscious rats to bolus injection of cholecystokinin-pancreozymin

Pancreatic secretion was studied in anaesthetized rats tested immediately after surgery or in conscious rats tested 48 hr after the cannulation of the pancreatic duct. Pancreatic flow, protein output and enzyme output were measured over a 30-min period in the unstimulated state and after the intravenous injection of bolus doses of cholecystokinin-pancreozymin (CCK-PZ) ranging from 1.25 to 20 Crick-Harper-Raper units (CHRU). Each animal received three doses of CCK-PZ, as either ascending or descending doses. In anaesthetized rats there was a linear relationship between the log-dose of CCK-PZ and the flow, protein and enzyme output with both the ascending and descending doses. In contrast, in conscious rats flow was unaffected by CCK-PZ, and protein output was greatest after the first dose, whether this was given in the ascending or descending doses. At all CCK-PZ levels flow in anaesthetized rats was less than that seen in conscious animals, but at doses of CCK-PZ above 5.00 CHRU protein output was greater in anaesthetized rats than in conscious rats. Ultrastructural studies of the pancreas showed areas of focal cytoplasmic degeneration and possible blockage of the duct with cellular debris after administration of high doses of CCK-PZ to conscious rats. These changes may be responsible for the reduced protein output with the second and third dose of CCK-PZ in these animals. No such changes were seen in anaesthetized rats after similar doses of CCK-PZ. These studies show fundamental differences in the response of the pancreas to CCK-PZ in anaesthetized and conscious rats. The mechanism for this difference is not clear, but it may represent a change in the normal response to CCK-PZ in the anaesthetized rats as a result of the effects of acute operative trauma, possibly acting through changes in pancreatic blood flow.     

Studies on the transport of vitamin D and of 25-hydroxyvitamin D in human plasma.

A study was conducted to investigate whether human plasma contains one or more than one protein for the transport of vitamin D and of 25-hydroxyvitamin D (25-OH-D).Serum was labeled in vivo with a mixture of radioactive vitamin D3 (derived from orally administered tracer vitamin D3) and of endogenously synthesized labeled 25-OH-D3. Samples of such serum were subjected to several different protein fractionation procedures. Only a single peak of protein-bound radioactivity was observed after each of these procedures. The fraction comprising the ascending and the descending limbs of the single peak of protein-bound radioactivity (after each procedure) were separately pooled. In each instance the ratio of radioactive 25-OH-D3 to radioactive vitamin D3 was found to be almost identical in both the ascending and the descending limbs. Taken together, these findings provide strong evidence that human serum contains only a single binding protein responsible for the normal transport of both vitamin D and 25-OH-D. Plasma labeled in vitro with added 3H-labeled 25-OH-D3 was subjected to gel filtration on Sephadex G-200 and to chromatography on columns of DEAE-cellulose and of SP-Sephadex. After each of these procedures a single peak of protein-bound radioactivity was observed, with elution profiles of protein and of radioactivity that were identical with those observed with in vivo labeled serum. These data indicate that tracer 25-OH-D3 added to plasma in vitro binds to the same plasma protein normally responsible for the transport of vitamin D and of 25-OH-D.     

An animal model for the measurement of acute tolerance to ethanol

An apparatus is described for the measurement of acute tolerance to ethanol in small animals. Male, Sprague-Dawley rats were trained on the apparatus to leap to a descending platform to avoid being shocked. After an i.p. injection of 2 g/kg ethanol, the rats were tested repeatedly on the apparatus, and the plasma ethanol concentration was measured after each trial. The results demonstrated that the jumping ability of the rats was significantly more impaired during the ascending portion of the plasma ethanol curve than during the descending portion of the curve. Furthermore, it was demonstrated that the improvement in jumping ability during the descending portion of the curve was not dependent on a lowered plasma ethanol concentration. In a second experiment, the possibility of practice effects was eliminated by measuring the jumping ability and plasma ethanol concentration in one group of rats on the ascending portion of the plasma ethanol curve and in another group on the descending portion of the curve. A significant improvement in jumping ability was again observed during the descending portion of the curve, even though the plasma ethanol concentrations of the two groups were comparable. The development of acute tolerance to ethanol was thus demonstrated in both experiments.     

Effect of realimentation and triiodothyronine on DNA synthesis in intact and partially resected rat liver

Whereas DNA synthesis in the liver of rats with permanent access to food fell markedly between the 72nd and 96th hour after partial hepatectomy, the decrease in the same post-operative interval in rats realimented after 3 days' starvation was less pronounced. The difference between the values in the control and the experimental group 96 hours after partial hepatectomy was statistically significant for p less than 0.01). In rats given glucose after the operation, 24 hours' realimentation caused a nonsignificant increase in DNA synthesis. The difference between the values 96 h after partial hepatectomy in this group and in the group fed the whole time on the standard diet was statistically significant for p less than 0.001. The administration of triiodothyronine (200 microgram/kg i.g.) to the above groups of rats at the outset of realimentation did not affect the development of changes in liver DNA synthesis. It likewise had no effect on the outcome of the realimentation of rats with an intact, unresected liver fed 3 days on plain glucose. In the intact control rats fed the whole time on the standard laboratory diet, triiodothyronine produced a distinct increase in liver DNA synthesis (p less than 0.01).     

Applying modern analogs to understand the pollen content of coprolites

Most scientists working with coprolites from archaeological contexts assume that human fecal specimens reflect the mixing of the pollen ingested during the period in which the contribution to the coprolite, 19 to 37.5 h, was ingested, that the amount of pollen in a fecal sample directly reflects the amount of pollen originally ingested during that interval, and that differences between the amounts of pollen in different fecal specimens reflect differences in the quantities of pollen ingested at different times. These assumptions were tested and found wanting in an experiment in which two persons sequentially ate separate quantities of 15 pollen types in meals over a four-day interval. The pollen was retrieved and analyzed from feces produced during those four days and five days of subsequent fecal production. Pollen ingested first appeared in relatively small amounts, usually the day after it was ingested. Its concentration per gram of sample then increased rapidly and remained high over a one to three day interval relative to the amounts in previous and subsequent fecal specimens deposited. When pollen concentrations declined some pollen was retained in the gastrointestinal system and much lower concentrations per gram of sample of each type continued to appear in fecal samples for several days. These relatively low pollen concentrations appeared in fecal samples approximately twice as often as did higher concentrations. Our results indicate that comparatively high pollen concentrations can be used to determine that a given pollen type was ingested, but comparisons between pollen concentrations of the same pollen type in different fecal specimens or between different pollen types in the same fecal specimen, cannot be used to determine whether different amounts of pollen were ingested, or what was the relative amount of each ingested. Because pollen concentrations per gram of sample varied widely with time since ingestion, percentages of given pollen types did not occur in predictable patterns and could actually increase as the concentration of the pollen type decreases. Hence, percentages should not be used in coprolite pollen analysis. The experimental results also suggest that variations in the pollen content of different portions of a coprolite are meaningful only in terms of the overall pattern of a sequential group of coprolites.