Difference In Transit Time Research Articles

Nasal mucociliary clearance in coal mine workers

Objective The purpose of this study was to analyze the effect of coal dust particles on nasal mucociliary function in coal mine workers. Method Using the saccharin method , nasal mucociliary clearance was determined for 77 subjects, of which 39 who worked in a coal mine were actively exposed to coal dust whereas 38 were unexposed control subjects. The measurements were performed in the coal mine, at the level of 170 m below sea level. Results The average saccharin nasal transit time in coal mine workers, 12.61 (SD: 4.30) minutes, is longer than that of the control subjects, 10.97 (SD: 3.22). Conclusion Although the findings of this study demonstrate that the coal particles affect the nasal mucociliary clearance, the difference in saccharin nasal transit time between the two groups (exposed vs unexposed) is not statistically significant ( P = 0.063).

Imaging electron waves

One can image the coherent flow of electron waves through a quantum point contact (QPC) into a two-dimensional electron gas by using scanning probe microscopy. A negatively charged tip depletes the electron gas below, backscatters electron waves, and reduces the QPC conductance. By raster scanning the tip over the sample, an image of electron flow is obtained. Images at liquid He temperatures show the individual quantum modes of the QPC. At greater distances, the electron flow forms narrow branches caused by small-angle scattering. Interference fringes in the images demonstrate the coherence of electron flow. An electron interferometer that acts as a quantum phase shifter was constructed by adding a gate to reflect electron waves back to the QPC, producing a V-shaped path for interfering electron waves with the apex at the QPC. When the length of one leg of the V is altered by changing the reflector gate voltage, the fringes at the other end of the V, under the tip, shift by the same distance. The interferometer is sensitive to transit time differences as small as ∼0.1 ps between the two electron paths. These observations are in good agreement with theoretical simulations of electron flow.

Recent Advances in the Use of Functional Foods: Effects of the Commercial Fermented Milk withBifidobacterium AnimalisStrain DN-173 010 and Yoghurt Strains on Gut Transit Time in the Elderly

Fermented milk products containing the probiotic strain Bifidobacterium animalis DN-173 010 (BM) have a beneficial effect in reducing gut transit times in a range of populations including adults and the elderly, especially female. The aims of this study were to investigate the efficacy of one and two servings per day of BM in elderly subjects and to determine the duration of the reduction in transit times after stopping consumption of the product. This was a randomized controlled and open study with four groups; 200 elderly subjects (aged 50 -75 years) were enrolled in the trial. In all, 100 subjects with medium transit times (MTT, 40-50 h) and 100 with slow transit times (STT, >50 h) were randomized to receive either 125 g or 250 g BMdaily for 2 weeks. Oro-faecal gut transit was determined by the use of coloured markers. Both dosages significantly reduced oro-faecal transit time with reductions of 20.5% and 42.2% observed in MTTsubjects receiving BM 125 g/ day and 250 g/day, respectively (p<0.0001). Corresponding reductions in STT subjects were 27.7% and 38.1%, respectively. The beneficial effects of BM lasted long after consumption of the product was stopped, with values returning to baseline in subjects with MTT at 6 weeks follow-up and in STT subjects consuming 125 g/day BM at 4 weeks follow-up. Significant differences in transit times were still observed at week 6 of follow-up in STT subjects receiving 250 g/day BM. This study completes and confirms the dose-dependent effects of BM from 0 to 250 g per day and can be compared with similar results obtained with 250 to 375g per day in a previous study on transit times in elderly subjects. It also demonstrates that there are significant beneficial effects long after consumption of the product has stopped. The results suggest an important role for this probiotic dairy product in fundamentally modulating gastrointestinal function that could beneficially affect the host, and hence reduce the susceptibility to conditions associated with delayed gut transit. Key words: Bifidobacterium animalis strain DN-173 010, Streptococcus thermophilus, Lactobacillus delbrueckii bulgaricus, probiotic, functional food, gut transit time.

Regional Differences in Blood Volume and Blood Transit Time in Resting Skeletal Muscle

We examined regional differences in blood volume and transit time along the length of a resting skeletal muscle by positron emission tomography. In contrast, blood volume didn't change. The blood transit time increased significantly from proximal to distal portions, suggesting that blood flow velocity slows even though there are no changes in blood volume.

Gender differences in irritable bowel syndrome

In the United States and other Western cultures, a greater number of women seek health care services for symptoms of functional pain disorders, including irritable bowel syndrome, than men. Recent clinical trials indicate that gender differences in responsiveness to drug therapy also occur. Several lines of inquiry have focused on explaining this gender-related difference due to the higher prevalence of these disorders in women. Evidence of a physiologic component is based on gender differences in gastrointestinal transit time, visceral sensitivity, central nervous system pain processing, and specific effects of estrogen and progesterone on gut function. Additional factors may play a role, including gender-related differences in neuroendocrine, autonomic nervous system, and stress reactivity, which are related to bowel function and pain. However, the link between these measures and gut motility or sensitivity remains to be clarified. Psychological characteristics, including somatization, depression, and anxiety as well as a history of sexual abuse, may also contribute to gender-related differences in the prevalence of irritable bowel syndrome. Although gender differences in the therapeutic benefit of serotonergic agents have been observed, less is known about potential differences in responsiveness to nondrug therapies for irritable bowel syndrome.GASTROENTEROLOGY 2002;123:1686-1701

Orocecal transit time in patients with functional dyspepsia.

The importance of intestinal dysmotility in functional dyspepsia is a controversial issue. To investigate the orocecal transit time in patients with functional dyspepsia, as well as a possible association between intestinal transit and the presence of anxiety or Helicobacter pylori infection in these patients. The participants in this study were 23 patients with dysmotility-like functional dyspepsia and 24 control subjects. Orocecal transit time was measured by the lactulose hydrogen breath test. The presence of anxiety was assessed by the Hospital Anxiety and Depression (HAD) scale. No significant difference in orocecal transit times was found between patients (median, 55 minutes; 95% confidence interval [CI], 40-60 minutes) and control subjects (median, 50 minutes; 95% CI, 40-60 minutes; p = 1). In the assessment, 15 patients (73%) scored for anxiety on the HAD scale, and 15 patients (65%) had positive test results for H. pylori. There was no significant difference in orocecal transit times between the patients with (median, 55 minutes; 95% CI, 40-63 minutes) and those without H. pylori infection (50 minutes; 95% CI, 40-68 minutes; p = 0.85), or between the patients with (median, 45 minutes; 95% CI, 40-68 minutes) and those without (60 minutes; 95% CI, 40-63 minutes; p = 0.77) anxiety. Orocecal transit time is within the normal range in patients with functional dyspepsia. Anxiety and H. pylori infection do not seem to influence orocecal transit time in these patients.

A revised shock time of arrival (STOA) model for interplanetary shock propagation: STOA‐2

We have examined a possibility for improvement of the STOA (Shock Time Of Arrival) model for interplanetary shock propagation. In the STOA model, the shock propagating velocity is given by Vs ∼ R−N with N = 0.5, where R is the heliocentric distance. Noting observational and numerical findings that the radial dependence of shock wave velocity depends on initial shock wave velocity, we suggest a simple modified STOA model (STOA‐2) which has a linear relationship between initial coronal shock wave velocity (Vis) and its deceleration exponent(N), N = 0.05 + 4 × 10−4Vis, where Vis is a numeric value expressed in units of km s−1. Our results show that the STOA‐2 model not only removes a systematic dependence of the transit time difference predicted by the previous STOA model on initial shock velocity, but also reduces the number of events with large transit time differences.

An improved method for Ra isotope ( 226Ra, 228Ra, 224Ra) measurements by gamma spectrometry in natural waters: application to CO 2-rich thermal waters from the French Massif Central

An improved method was developed to measure 226Ra, 228Ra and 224Ra in freshwaters by gamma spectrometry. Radium was selectively extracted from acidified samples using specific filters (3M EMPORE™ Radium Rad disks). The latter was subsequently analysed by gamma spectrometry. Simultaneous and direct determination of the activities of the three isotopes was performed by comparison of gamma rays of the Radium Rad disks with those of a calibrated standard disk. This efficient and reliable method allowed a reduction of sample processing to a few hours. This technique was applied to analyse the Ra isotope compositions of several CO 2-rich hydrothermal springs of the western border of the Limagne graben (French Massif Central). The studied springs emerge from a succession of granitic outcrops lined up along a major fault. Their chemical compositions evolve from calcic and magnesian chloro-bicarbonated to sodic bicarbonated. All the springs display high Ra activities, probably linked to high CO 2 content and/or high cation content of these waters, with various Ra isotope ratios. 226Ra activity ranges from 588 to 2287 mBq/l and 228Ra activity from 260 to 1590 mBq/l, whereas 224Ra displays an activity between 245 and 1808 mBq/l. Four of the six analysed springs have ( 228Ra/ 226Ra) activity ratios lower than 0.7, thus, significantly lower than the ratio expected from an interaction with a calc-alkaline granitoid (typically having ( 232Th/ 238U) activity ratio between 1 and 2). Low ( 228Ra/ 226Ra) ratio (0.27) of the northern water (Montpensier) suggests the existence in this area of a zone of U concentration, possibly resulting from U mobilization and accumulation induced by previous hydrothermal events. The ( 224Ra/ 228Ra) ratios display smaller variations. They suggest short transit times from the zone of Ra leaching to the surface (a few days) or a very shallow addition of 224Ra (e.g., from a localised zone where 228Th could be preferentially adsorbed on the mineral surfaces). In some cases, these ratios might be used to infer differences in transit times of waters between neighboring springs.

The difference in pulse transit time to the toe and finger measured by photoplethysmography

Blood pressure pulse wave velocity (PWV) is a parameter which is related to arterial distensibility. Its direct assessment, by measuring the appearance time of a pressure pulse in two sites along an artery and the distance between the two sites, is complicated and inaccurate. In the current study, pulse transit time (PTT) to the toes and fingers of 44 normotensive male subjects was measured by photoplethysmography (PPG) and ECG. The arrival time of the pulses at the toe and finger was determined from the foot of the systolic rise of the PPG signal, i.e. at end-diastolic time. Two parameters, which are related to PWV, were tested: the time delay between the ECG R-wave and the arrival time of the pulses at the toe (E-T PTT), and the difference in the transit time of the blood pressure pulses between the toe and finger (T-F PTTD). E-T PTT and T-F PTTD decreased as functions of the subject's age and systolic blood pressure (SBP), but their dependence on the diastolic blood pressure (DBP) was not statistically significant. The decrease of the PTT parameters with age is attributed to the direct structural decrease of the arterial compliance with age and not to functional effects associated with the increase of the blood pressure with age, since the PTT parameters did not depend on DBP though the measurements were performed at end-diastole.

The gastrointestinal transit profile of 14C-labelled poly(acrylic acids): : an in vivo study

The gastrointestinal distribution profiles for three 14C-labelled poly(acrylic acid)s of different average molecular weights and degrees of cross-linking have been established using the rat model. Despite initial differences in transit times and retention characteristics, these structural features were found to be of little influence to the overall gastrointestinal transit of the materials under consideration. No evidence for the systemic absorption of any of the polymers could be identified.

Comparison of Intradermal and Subcutaneous Injections in Lymphatic Mapping

Background. Sentinel node biopsy (SNB) for melanoma, with its intradermal (ID) injection, has a higher success rate than SNB for breast cancer, which is typically performed with a subcutaneous (SC) or peritumor injection. It is hypothesized that this is in part due to a slower transit time of lymphatic mapping agents through the parenchymal lymphatics of the breast. No study has investigated differences in transit time between different tissues to account for this clinical observation. The goal of the study was to compare transit time between ID and SC injections with common agents used in lymphatic mapping.Methods. Four injection sites on five domestic pigs were used. Sites were bilateral and included cervical, forelimb, hindlimb, and flank areas. Agents included technetium sulfur colloid (Tc99, filtered and unfiltered), isosulfan blue (IB) dye, and fluorescein (FL) dye. At each site both ID and SC injections were made and the transit time to reach the sentinel node was recorded. The transit time differences were calculated per centimeter distance from the draining lymph node basin.Results. Sentinel nodes were identified draining all sites and found to be hot, blue, or fluorescent (using a Wood's lamp for identification). The cervical and forelimb injection sites drained to the same cervical lymph node basin and both SC and ID injection sites drained to the same sentinel node. Similarly, the hindlimb and flank injection sites both drained to inguinal lymph node basins. The slowest transit time occurred with Tc99 injected SC and the fastest occurred with Tc99 injected ID, whereas both FL dye and IB traveled rapidly to the sentinel node whether injected SC or ID. Large differences were found using unfiltered Tc99 depending on its injection ID (2.7 s/cm ± 0.5) vs SC (249 s/cm ± 14.7, P = 0.008).Conclusions. Tc99 ID injections were significantly faster than SC injection. The slowest and fastest SC injection agents were unfiltered Tc99 and IB, respectively. Dermal injections provide faster transit of lymphatic agents and may improve the identification rate when applied to patients with breast cancer.

Comparative study of electron transit times evaluated by DD, HD, and MC device simulation for a SiGe HBT

Transit times of a silicon/germanium heterojunction bipolar transistor (HBT) with a base width of 24 nm are investigated in the quasi-stationary limit for the first time by consistent drift-diffusion (DD), hydrodynamic (HD), and fullband Monte Carlo (MC) simulations. The quasi-ballistic transport in the base and collector leading to a strong velocity overshoot is well described by the HD model and corresponding transit times are in good agreement with the MC results. On the other hand, the DD model fails in this region and substantially overestimates the base transit time bearing the possibility of wrong guidelines for transistor design optimization. However, since the base transit time is no longer dominating the cutoff frequency of high-speed HBTs, the failure of the DD model leads to an underestimation of the peak cutoff frequency by only 10%. Close to high injection differences in the emitter transit times of the HD and MC model are observed which are mainly related to small differences in the Gummel plot.

Seasonal energetic parameters of free-grazing bison (Bison bison)

Seasonal energetic parameters of yearling bison were estimated using the bite-count and single marker methods (fieldtrials) during each solstice and equinox between June 1994 and December 1995. To calibrate the marker method and to provide a controlled estimate of seasonal requirements, balance trials were conducted in metabolism crates during winter solstice 1994 and summer solstice 1995 (pen trials). In pen trials, actual metabolizable energy (ME) intake was lower (P &lt; 0.01) during winter (528 ± 51 kJ W−0.75 d−1) than in summer (917 ± 69 kJ W−0.75 d−1). Similarly, in field trials, estimated ME intakes were lower for both bite count (P &lt; 0.01) and marker methods (P &lt; 0.05) during winter (819 ± 375, 146 ± 105 kJ W−0.75 d−1) than summer (1977 ± 186, 408 ± 53 kJ W−0.75 d−1), respectively. Estimated ME requirements (actual intake, pen trials) were 532 ± 178 kJ W−0.75 d−1 in winter and 956 ± 107 kJ W−0.75 d−1 in summer. In field trials, estimated ME requirements (marker method) ranged from 146 ± 22 kJ W−0.75 d−1 (December 1994) to 478 ± 45 kJ W−0.75 d−1 (June 1995). Seasonal variation (P &lt; 0.05) in total digesta turnover time (46.4 ± 1.4 h, December 1994; 24.9 ± 2.7 h, June 1995) was related more consistently to seasonal differences in transit time (18.2 ± 1.2 h, 4.0 ± 0.8 h, respectively) than differences in reticulo-rumen and lower tract turnover time. Bison exhibited strong seasonal differences in energetic parameters like other northern wild ruminants. Key words: Bison, seasonality, metabolizable energy requirements, intake, excretion parameters, grazing

Variability of photoplethysmography peripheral pulse measurements at the ears, thumbs and toes

Pulses radiating to the periphery after each heart beat can be detected by photoplethysmography (PPG). A multi-site PPG measurement and analysis system is described for beat-to-beat analysis of the pulse waveforms. Waveforms were collected from the right and left ear lobes, thumb pads, and toe pads of 20 normal subjects whilst they performed paced breathing. The median coefficients of variation for pulse amplitude were; ears and thumbs 11%, and toes 14%. Significant differences in pulse transit time of 4 ms (to foot of pulse), and 14 ms (to peak of pulse) between the right and left toes were detected (right lagging left, p &lt; 0.01). The median pulse transit times (to foot) were; ears (0.133 s), thumbs (0.199 s), and toes (0.301 s), with coefficients of variation; 2.8%, 2.2%, and 1.6%, respectively. The median pulse transit times (to peak) were; ears (0.397 s), thumbs (0.436 s), and toes (0.515 s), with coefficients of variation; 1.4%, 2.0%, and 1.5%, respectively. The authors have utilised signal processing algorithms to calculate beat-to-beat measures of pulsatility, and determined normative data for multi-site PPG pulse assessments.

Anastomotic configuration and mucosal 5-aminosalicylic acid (5-ASA) concentrations in patients with crohn’s disease: a GISC study

OBJECTIVE: Recurrence of Crohn’s disease quite inevitably occurs after resection of distal small bowel and proximal colon, involving the neoterminal ileum close to the anastomosis. Oral 5-aminosalicylic acid (5-ASA) administered soon after surgery delays recurrence and reduces its severity. We recently observed that in operated patients submitted to prophylactic treatment with oral 5-ASA the rate of recurrence was significantly higher in those with end-to-end anastomosis than in those with other types of anastomosis (end-to-side, side-to-side). The hypothesis investigated in the present study was that patients with end-to-side or side-to-side anastomosis would benefit from a higher mucosal concentration of 5-ASA with respect to patients with end-to-end anastomosis. Therefore, the mucosal 5-ASA concentration was measured in the perianastomotic area of both groups. METHODS: The study was carried out in 19 patients submitted to radical surgery for Crohn’s ileitis or ileocolitis, under oral prophylactic treatment with 5-ASA (Asacol). All patients were on regular endoscopic follow-up and were free of recurrence. Two biopsies were collected 3 cm from the anastomosis, in the neoterminal ileum, and two biopsies were collected at the colonic site 3 cm below the anastomosis. 5-ASA concentrations (ng/mg) were measured in tissue homogenates by high-performance liquid chromatography (HPLC) with electrochemical detection. RESULTS: The mucosal concentration of 5-ASA in the neoterminal ileum was significantly lower in patients with end-to-end anastomosis than in those with other types of anastomosis (median values: 29.4 ng/mg vs 92.9 ng/mg respectively; p < 0.001). Six of 10 patients (60%) with end-to-end anastomosis, but none of the nine patients with other types of anastomosis, showed 5-ASA mucosal concentrations <40 ng/mg at the neoterminal ileum. On the contrary, no patients with end-to-end anastomosis showed mucosal concentrations of 5-ASA >90 ng/mg, compared with the 57% of patients in the group with other types of anastomosis. No differences were observed for colonic biopsies. CONCLUSIONS: The different mucosal concentrations in these two groups may be explained by the difference in segmental transit time induced by the different anastomotic configurations. A slower preanastomotic transit time, demonstrated in patients with end-to-side or side-to-side anastomosis, could offer a prolonged contact time between the intestinal content and the mucosa, resulting in an increase in drug absorption.

Anastomotic configuration and mucosal 5-aminosalicyclic acid (5-ASA) concentrations in patients with Crohn's disease: a GISC study. Gruppo Italiano per lo Studio del Colon e del Retto.

Recurrence of Crohn's disease quite inevitably occurs after resection of distal small bowel and proximal colon, involving the neoterminal ileum close to the anastomosis. Oral 5-aminosalicylic acid (5-ASA) administered soon after surgery delays recurrence and reduces its severity. We recently observed that in operated patients submitted to prophylactic treatment with oral 5-ASA the rate of recurrence was significantly higher in those with end-to-end anastomosis than in those with other types of anastomosis (end-to-side, side-to-side). The hypothesis investigated in the present study was that patients with end-to-side or side-to-side anastomosis would benefit from a higher mucosal concentration of 5-ASA with respect to patients with end-to-end anastomosis. Therefore, the mucosal 5-ASA concentration was measured in the perianastomotic area of both groups. The study was carried out in 19 patients submitted to radical surgery for Crohn's ileitis or ileocolitis, under oral prophylactic treatment with 5-ASA (Asacol). All patients were on regular endoscopic follow-up and were free of recurrence. Two biopsies were collected 3 cm from the anastomosis, in the neoterminal ileum, and two biopsies were collected at the colonic site 3 cm below the anastomosis. 5-ASA concentrations (ng/mg) were measured in tissue homogenates by high-performance liquid chromatography (HPLC) with electrochemical detection. The mucosal concentration of 5-ASA in the neoterminal ileum was significantly lower in patients with end-to-end anastomosis than in those with other types of anastomosis (median values: 29.4 ng/mg vs 92.9 ng/mg respectively; p < 0.001). Six of 10 patients (60%) with end-to-end anastomosis, but none of the nine patients with other types of anastomosis, showed 5-ASA mucosal concentrations <40 ng/mg at the neoterminal ileum. On the contrary, no patients with end-to-end anastomosis showed mucosal concentrations of 5-ASA >90 ng/mg, compared with the 57% of patients in the group with other types of anastomosis. No differences were observed for colonic biopsies. The different mucosal concentrations in these two groups may be explained by the difference in segmental transit time induced by the different anastomotic configurations. A slower preanastomotic transit time, demonstrated in patients with end-to-side or side-to-side anastomosis, could offer a prolonged contact time between the intestinal content and the mucosa, resulting in an increase in drug absorption.

Total and segmental colonic transit time in constipated patients with Chagas' disease without megaesophagus or megacolon.

Manometric and pharmacological tests have shown that motor abnormalities may occur in the non-dilated colons of chagasic patients. In order to investigate the presence of abnormalities of colonic function in constipated patients with Chagas' disease (ChC) without megaesophagus or megacolon, studies of total and segmental colonic transit time with radiopaque markers were performed on 15 ChC patients, 27 healthy volunteers and 17 patients with idiopathic constipation (IC). The values obtained for the control group were similar to those reported in the literature (total colonic time: 34. 1 +/- 15.6 h; right colon: 9.9 +/- 7.3 h; left colon: 10.8 +/- 10 h, and rectosigmoid: 12.6 +/- 9.9 h). Colonic transit time data permitted us to divide both IC and ChC patients into groups with normal transit and those with slow colonic transit. Colonic inertia was detected in 41% of IC patients and in 13% of ChC patients; left colon isolated stasis (hindgut dysfunction) was detected in 12% of IC patients and 7% of ChC patients, and outlet obstruction was detected in 6% of IC patients and 7% of ChC patients. There were no significant differences in total or segmental colonic transit times between slow transit IC and slow transit ChC patients. In conclusion, an impairment of colonic motility was detected in about 30% of constipated patients with Chagas' disease without megaesophagus or megacolon. This subgroup of patients presented no distinctive clinical feature or pattern of colonic dysmotility when compared to patients with slow transit idiopathic constipation.

A photomultiplier tube for a NT-200 deep-underwater neutrino telescope

A fast, high-sensitive photomultiplier tube (PMT) with a 25-mm diameter bialkali photocathode is being developed to be used as part of a KBA3AP-370 hybrid photodetector. Its linearity is ∼ 150 mA. The rise time of an anode current pulse is ∼ 2 ns. The transit time difference of photoelectrons originating from different points of the photocathode does not exceed 1 ns.

The postnatal age of rat lung fibroblasts influences G1/S phase transition in vitro.

In the neonatal rat lung, alveolar development occurs from postnatal Days 4-13, during which time there is a fourfold increase in interstitial fibroblasts. Factors influencing emergence of new septa and cell proliferation associated with septal elongation have yet to be identified, in part because of difficulties inherent in studying this process in vivo. Using flow cytometric analysis of the DNA content of freshly isolated lung fibroblasts, we found that proliferation, as indicated by the percentage of cells in S plus G2/M phases, peaked on postnatal Day 4 (P < 0.04). By Days 9-10 the proliferation rate was lower than on Days 3, 4, 5, or 6 (P < 0.005). We then evaluated rates of in vitro proliferation as a function of postnatal age in first passage fibroblasts and found that the proliferative phenotype expressed in vivo persists in vitro. Fibroblasts from 4-5-d-old pups increased in number and incorporated 3H-thymidine at a faster rate than did fibroblasts obtained from pups at other postnatal ages (P < 0.0001). Age-dependent differences in cell cycle transit time were compared in fibroblasts synchronized by serum starvation and analyzed by flow cytometry at 2-h intervals from 13-21 h after release from serum starvation. A greater percentage of cells from 5-d-old pups entered S phase during this period than was seen for cells obtained from 2-, 9-, 13-, or 23-d-old rat pups (P = 0.0001). Cells from 5-, 9-, and 13-d-old pups reentered G0/G1 by 21 h after release from serum starvation, in contrast to fibroblasts from 2- and 23-d-old rats which did not. Throughout the 15-h period after release from serum starvation, levels of cyclin E, which peaks at the G1/S border, were highest in the 5-d-old cells (P < 0.025). Synchronization with 2.5 mM hydroxyurea which inhibits DNA synthesis completely abolished age-related differences in cell cycle transit time, implying that age-dependent differences in lung fibroblast proliferation rates are the result of events occurring before S-phase entry.

Modified small-bowel follow-through: use of methylcellulose to improve bowel transradiance and prepare barium suspension.

To evaluate the efficacy of barium suspension prepared in methylcellulose (MC) in modified small-bowel follow-through (SBFT). The authors evaluated 155 patients who underwent modified SBFT with oral administration of MC after ingesting barium suspension. Of these patients, 52 received 40% suspension in MC, 46 received 40% suspension in water, and 57 received 70% suspension in water. Patients were divided into normal (n = 74) and abnormal (n = 81) groups according to the final results. The image quality, transit time to the cecum, and time to and frequency of flocculation were compared for both groups. In the normal group, the quality of the images in patients receiving 40% suspension in MC or 70% suspension in water was superior to that of images in patients receiving 40% suspension in water. In the abnormal group, the best image quality was achieved for the patients who received 40% suspension in MC. In the normal group, the difference in transit time between the three preparations was not substantial. In the abnormal group, however, the 40% suspension in MC showed the fastest transit time. Use of the 40% suspension in MC helped lower the frequency of flocculation in the normal group. Use of 40% barium suspension in MC is effective for improving the image quality in modified SBFT.