Time Of First Appearance Research Articles

Molecular Dynamics Investigation of the Transient Regime in the Freezing of Salt Clusters

Molecular dynamics (MD) investigations of the freezing of supercooled liquids can identify nuclei far smaller than can be detected in laboratory experiments, to date, and consequently can provide information about nucleation so far inaccessible to experiment. In a recent MD study of the freezing of clusters of SeF6, a new method of recording nucleation events was introduced. It involved the observation of times of first appearance of nuclei of the size of n. An advantage of the new approach is that it provides information about the size of the critical nucleus. For nuclei smaller than the critical size, it also avoids the overshoots of nucleation rates that precluded the application of the Miloshev-Wu method in the subcritical region. Kinetic information in the transient regime can be characterized by three parameters, the time lag, the reduced moment, and the steady state nucleation rate. To get some idea of how general the new approach is, a very different system was investigated, that of clusters of NaCl. Two different fitting functions were used to analyze the results. The first one adopted the log-normal probability distribution of Wu. The second function was a modification of Shneidman's analytical solution appropriate for large nuclei. The second function gave a rather good account of MD data for all nuclear sizes and temperatures and gave more stable results in the subcritical region. Several inferences of the sizes of critical nuclei were made. Applying the criterion for n* based on the Zeldovich solution of the Becker-Döring equations, we estimated the critical nucleus sizes to be 14, 18, and 24 ions for quench temperatures of 640, 690, and 740 K, respectively. Even though the interionic interactions initiating nucleation in salt are very different from the van der Waals interactions in clusters of SeF6, the characteristic aspects of the transient regimes of the two systems were quite similar.

Is Euro-Collins better than ringer lactate in live related donor renal transplantation?

Objectives:Euro-Collins and University of Wisconsin are preferred solutions in cadaveric renal transplantation. There are no guidelines regarding the perfusion fluids in live donor renal transplantation. We studied whether Euro-Collins was better than Ringer lactate in terms of protecting allograft function.Materials and Methods:A double-blind permuted randomized trial comparing Euro-Collins and Ringer lactate was performed on 100 patients undergoing live related donor renal transplantation. Outcome variable was serum creatinine.Results:Age, sex, donor nephrectomy and ischemia times, kidney temperature, time of first appearance of urine was not significantly different in both the groups. Fall in serum creatinine was significantly more in Euro-Collins than Ringer lactate in the first postoperative week (P-<0.05). The time to reach nadir creatinine was 4.97 days in Euro-Collins and 7.75 days in the Ringer lactate group (P-0.088). Serum creatinine was significantly lower in the Euro-Collins group till six months, thereafter it equalized with Ringer lactate. When individual parameters were analyzed for time to nadir creatinine, only the cold ischemia time of > 80 min was found to be significant (P-0.024). Twelve kidneys in Euro-Collins and 17 in the Ringer lactate group had cold ischemia times of ≥80 min and time to nadir creatinine was 4.33 ±3.74 and 12.76± 12.68 days (P-0.035).Conclusions:Renal function normalized rapidly when Euro-Collins was used. Cold ischemia time of ≥ 80 min was the most important factor affecting the graft function and perfusing with Euro-Collins could protect the allograft.

A new procedure for analyzing the nucleation kinetics of freezing in computer simulation

A new method for deriving the size of the critical nucleus and the Zeldovich factor directly from kinetic data is presented. Moreover, in principle, the form of G(n), the free energy of formation of nuclei consisting of n molecules, can be inferred. The method involves measuring times of first appearance of nuclei of size n in the transient regime and applying the Becker-Doring theory. Times of first appearance exhibit the same characteristics as the conventional times associated with N(n,t), the number of nuclei of at least size n per unit volume that have materialized at time t. That is, they are well represented by three nucleation parameters, the reduced moment, the time lag, and the steady state nucleation rate. But unlike the conventional steady state rate which is independent of n, the steady state times of first appearance vary with n. In order to characterize the three nucleation parameters with precision, however, thousands of independent stochastic events with known n are required. Such sets of data are readily generated in molecular dynamic simulations but, so far, not in laboratory experiments. Results are illustrated by an analysis of simulations of the spontaneous freezing of large clusters of SeF6.

Root Zone Temperature as Modified by Plastic Mulches Affect the Appearance of First Systemic Symptoms of Tomato Spotted Wilt and Fruit Yield in Tomato

Tomato spotted wilt (TSW) is a serious constraint to tomato production in various regions of the world. The effect of TSW on tomato yield is largely influenced by time of infection. Early infection usually results in severe stunting of the seedling and even death of the plant. Plastic mulches have been found to affect both the incidence of TSW, and plant growth and yield of tomato. The objective of this study was to determine the effect of root zone temperature (RZT) as affected by plastic mulch on the timing of appearance of first TSW symptoms, vegetative top fresh weight (FW) and fruit FW in tomato. Under natural TSW infection as well as in artificially inoculated plants, vegetative top FW and fruit FW were both linearly related with number of days after transplanting (DAT) the plants were free from TSW symptoms. The plants grown on black mulch during the fall showed earlier appearance of TSW symptoms, and had significantly reduced vegetative growth and fruit yields. The mean RZT during the first 42 DAT—the time before the plants reached full canopy closure—significantly affected the timing of first appearance of TSW symptoms, tomato plant growth and fruit yield. Vegetative top FW (optimal RZT = 24.1 °C) and fruit FW (26.9 °C) fitted the quadratic relationships with the mean RZT during the first 42 DAT. In conclusion, utilization of plastic mulches that created conditions of RZT stress, particularly heat stress, resulted in reduced plant growth and yield and may predispose the plants to earlier expression of TSW symptoms compared to plants grown under RZTs more favorable to tomato plant growth.

Regulation of AUXIN RESPONSE FACTOR3 by TAS3 ta-siRNA Affects Developmental Timing and Patterning in Arabidopsis

MicroRNAs (miRNAs) and trans-acting siRNAs (ta-siRNAs) in plants form through distinct pathways, although they function as negative regulators of mRNA targets by similar mechanisms . Three ta-siRNA gene families (TAS1, TAS2, and TAS3) are known in Arabidopsis thaliana. Biogenesis of TAS3 ta-siRNAs, which target mRNAs encoding several AUXIN RESPONSE FACTORs (including ARF3/ETTIN and ARF4 ) involves miR390-guided processing of primary transcripts, conversion of a precursor to dsRNA through RNA-DEPENDENT RNA POLYMERASE6 (RDR6) activity, and sequential DICER-LIKE4 (DCL4)-mediated cleavage events. We show that the juvenile-to-adult phase transition is normally suppressed by TAS3 ta-siRNAs, in an ARGONAUTE7-dependent manner, through negative regulation of ARF3 mRNA. Expression of a nontargeted ARF3 mutant (ARF3mut) in a wild-type background reproduced the phase-change phenotypes detected in rdr6-15 and dcl4-2 mutants, which lose all ta-siRNAs. Expression of either ARF3 or ARF3mut in rdr6-15 plants, in which both endogenous and transgenic copies of ARF3 were derepressed, resulted in further acceleration of phase change and severe morphological and patterning defects of leaves and floral organs. In light of the functions of ARF3 and ARF4 in organ asymmetry, these data reveal multiple roles for TAS3 ta-siRNA-mediated regulation of ARF genes in developmental timing and patterning.

The effects of phytase on growth performance and intestinal transit time of broilers fed nutritionally adequate diets and diets deficient in calcium and phosphorus

Five experiments (Exp.) were conducted to determine the effects of phytase on growth performance and intestinal transit time in chicks fed nutritionally adequate diets and diets deficient in Ca and nonphytate P (nPP). In Exp. 1 and 2, chicks were fed a nutritionally adequate diet from 0 to 6 d or from 0 to 4 d posthatching; assay periods were 8 or 10 d; average initial BW were 98 or 79 g; and average final BW were 371 or 369 g, respectively. Treatments were replicated with 12 pens of 5 chicks each. Corn-soybean meal (C-SBM) diets were adequate in all nutrients except Ca and nPP where appropriate. The treatments were 1) C-SBM, 1.0% Ca, and 0.45% nPP; 2) C-SBM, 0.80% Ca, and 0.25% nPP; 3) Diet 1 + 600 phytase units/kg of diet; 4) Diet 2 + 600 phytase units/kg of diet. Experiments 3, 4, and 5 were conducted to determine the effects of phytase on intestinal transit time in broilers. Broilers were fed the same nutritionally adequate diet from 0 to 18, 27, or 23 d posthatching, and the assay periods were 7 d. Treatments were replicated with 18 individually penned broilers. Average initial BW were 768, 1,108, or 838 g, and average final BW were 1,299, 1,704, or 1,392 g in Exp. 3 to 5, respectively. Transit time data were collected on d 1 and 7 of the Exp. Diets were 1) C-SBM, 0.9% Ca, and 0.35% nPP; 2) C-SBM, 0.80% Ca, and 0.25% nPP + 600 phytase units/kg of diet. Transit time was calculated as the difference between the time feed was first ingested and the time of first appearance of solid feces. In Exp. 1 and 2, the reduction in dietary Ca and nPP reduced (P < 0.01) average daily gain (ADG), average daily feed intake (ADFI), and gain:feed. Phytase addition increased (P < 0.02) ADG and ADFI in diets deficient in Ca and nPP and in the nutritionally adequate diets. In Exp. 2, the reduction in Ca and nPP reduced (P < 0.01) toe and tibia ash percentage, but phytase addition increased (P < 0.01) toe and tibia ash percentage. The increase in toe ash percentage was greater in chicks fed the Ca and nPP deficient diet than in chicks fed the nutritionally adequate diet (Ca and nPP × phytase, P < 0.01). In Exp. 3, 4, and 5, transit time on d 1 was faster (P < 0.03) in chicks fed phytase. On d 7, transit time tended to be faster in chicks fed phytase, but the effect was not significant (P = 0.15). These data indicate that phytase increases ADG and ADFI in diets deficient in Ca and nPP and in diets formulated to be adequate (or excess) in all nutrients for broiler chicks. The increase in ADG and ADFI in chicks fed the nutritionally adequate diet may be due to a faster transit time of feed through the digestive tract, resulting in a greater feed intake and gain.

Scyphozoa in the Bornholm Basin (central Baltic Sea)–The role of advection

The usual absence of ephyrae and late appearance of medusae of the Scyphozoa Aurelia aurita and Cyanea capillata in the Bornholm Basin (BB; central Baltic Sea) indicate that these species are not strobilating in the region and their presence depends on advection. To study their potential origin we compared drift from historically known strobilation areas derived from a circulation model with spatial distributions observed during 19 cruises in the BB during 2002 and 2003. The model results are in good accordance with the field observations. According to the model results inter-annual differences in the timing of first appearance and life stage at appearance of A. aurita were clearly related to differences in the hydrodynamic regime during the investigation periods. During the stagnation regime in 2002 young medusae occurred first in June in the BB. In contrast, in 2003 fast transport due to several inflow events advected ephyrae released between January and March in the western Baltic already in April to the BB. Although the Gullmar Fjord (western Sweden) is the nearest known strobilation area for C. capillata, the model did not support advection from there in numbers explaining the occurrence of this species in the BB in 2002 and 2003. If the model works adequately in this regions we have to assume that the Gullmar Fjord is not a main source region of C. capillata in the BB, but other strobilation areas in the Kattegat or the North Sea appear more important. Our results imply that advection and inflow events are critical for the occurrence and distribution of early stages of jellyfish in the central Baltic Sea. They demonstrate the potential of circulation models as tools to study the effect of long-range transport on the spatial composition of these organisms.

Accounting for marker disassociation when modelling time-dependent ruminal escape of particles based on the faecal excretion of Ytterbium

One of the problems with using rare-earth metals as fibre-bound markers for digestive tract passage investigations in ruminants is that of marker disassociation (leaching) from the fibre and the more rapid movement of disassociated marker through the whole gastrointestinal tract with the liquid phase. Analysing the course of marker concentrations in faecal samples from cattle, sheep and goats fed millet leaves, bush hay or green forage and given a pulse dose of Ytterbium (Yb) bound to fibre particles, it was found that in 28 out of 135 obtained marker excretion curves the Yb-concentrations in the first three faecal samples (excreted 0–16 h after dosing) significantly differed from background values, while this was not the case for the remaining curves. Repeating experiments where marker disassociation has occurred might not always be possible. Therefore, a single compartment model was developed to simulate this disassociation, the ruminal escape of fibre-bound marker assumed to be Gamma-2 dependent, whereas the disassociation and subsequent passage of the marker with the liquid phase were taken to be Gamma-1 (exponentially) dependent. This model, as well as a single compartment model not accounting for marker disassociation, were fitted to the relevant data sets and the results compared. The maximum predicted level of marker disassociation was found to be 45% of the total marker dose. Modelling data sets with marker disassociation with a model not allowing for this resulted in an overestimation of the time taken for half the amount of marker to escape from the rumen ( T 50) by a maximum of 29.5 h, which could be attributed to a distortion of the curve towards a reduction in the time of first appearance of the fibre-bound marker (TT f). The possible reasons for disassociation of Yb as well as a method for the determination of T 50 where this cannot be obtained arithmetically are discussed.

LARGE-SCALE, POLYMERASE CHAIN REACTION–BASED SURVEILLANCE OF SCHISTOSOMA HAEMATOBIUM DNA IN SNAILS FROM TRANSMISSION SITES IN COASTAL KENYA: A NEW TOOL FOR STUDYING THE DYNAMICS OF SNAIL INFECTION

Levels of prepatent Schistosoma haematobium infection were monitored in intermediate host snails (Bulinus nasutus) collected from transmission sites in coastal Kenya, using a polymerase chain reaction (PCR) assay amplifying the Dra I repeated sequence of S. haematobium. The timing and number of prepatent and patent infections were determined for each site and, where the time of first appearance was clear, the minimal prepatent period was estimated to be five weeks. High, persistent, prepatency rates (range = 28-54%), indicated a significant degree of repeated area contamination with parasite ova. In contrast, rates of cercarial shedding proved locally variable, and were either low (range = 0.14-3.4%) or altogether absent, indicating that only a small proportion of infected snails reach the stage of cercarial shedding. Given the apparently strong focal effects of environmental conditions, implications of these new data are discussed regarding the estimation of local force of transmission and the design of control activities.

Characterizing gastrointestinal transit time in four lemur species using barium‐impregnated polyethylene spheres (BIPS)

Differences in dietary profiles and gastrointestinal (GI) morphologies observed across lemur species suggest that there may be variation in patterns of digesta flow through the GI tract related to the method of digesta processing. Using radio-opaque barium-impregnated polyethylene spheres (BIPS), we characterized such patterns in four lemur species: Varecia variegata (VV), Eulemur fulvus (EF), Propithecus verreauxi (PV), and Hapalemur griseus (HG) (n = 2 per species). After an initial radiograph was taken under light sedation, the animals were fed the BIPS together with a small meal. A combination of 30 small (1.5 mm) and 10 large (5 mm) BIPS was administered. Radiographs were then taken on a species-dependent basis up to 48 hr post-dosage. For small BIPS, the gastric transit time (GTT; time of first exit of BIPS from stomach) was 0.25-2 hr for VV, EF, and HG, and approximately 10 hr for PV. The oro-rectal transit time (ORTT; time of first appearance in the rectum) was < 2 hr for VV and EF, and 24.0 hr for PV and HG. The intestinal transit time (ITT, measured as ORTT - GTT) was < 1.5 hr for VV and EF, and approximately 14 hr and 22 hr for PV and HG, respectively. These data suggest that the GTT of digesta as measured with BIPS was rapid for VV, EF, and HG. For VV and EF, the ORTT and ITT were also rapid, while for HG they were much slower. PV was characterized by delayed GTT, and a more rapid ITT compared to HG. Thus, patterns of flow for PV and HG, despite similar ORTT, differed in that HG emptied BIPS more rapidly and ITT was slower. The flow of BIPS did not differ for VV and EF. These data reveal new information in addition to the total tract transit time, and complement existing knowledge regarding anatomy and diet.

Spatially quantitative control of the number of cotyledons in a clonal population of somatic embryos of hybrid larch Larix x leptoeuropaea.

Many conifer embryos, both in natural seeds and in clonal populations of somatic embryos, display variability in the number of cotyledons. In hybrid larch, Larix x leptoeuropaea (synonymous with L. x marschlinsii Coaz), such variability has previously been reported in somatic embryos, together with a decrease in the average cotyledon number when benzyladenine (BA) is applied exogenously. Described here is a spatially quantitative study with the aim of throwing some light on the way cotyledon number is determined, and hence the mechanism of cotyledon formation. Stock cultures of embryogenic tissue were maintained and later made embryogenically active by standard methods. Development through cotyledon formation was followed by optical microscopy with quantitative measurement of embryo diameter and number of cotyledons. SEMs of representative stages and cotyledon numbers were done for purposes of illustration in this account. Existing mathematics of waveforms on a disc were cast into a form suitable to compare with the quantitative data. The number of cotyledons is linearly related to the diameter of the apical surface of the embryo (which approximates a circular disc) at the time of first appearance of the cotyledon primordia. This linearity is a constant-spacing phenomenon between adjacent primordia. Addition of BA to the medium restricts the range of apical diameters without changing inter-cotyledon spacing. Slope/intercept ratio of the linear plot matches expectation for initiation of cotyledon pattern as a harmonic waveform on a circular disc. The entire pattern of cotyledon primordia arises as a single entity coordinated by a mechanism with wave-forming properties. This is explicable by diverse mechanisms, especially either mechanical buckling ('biophysical') or reaction-diffusion kinetics ('physicochemical').

Contrast M‐Mode Power Doppler Ultrasound in the Detection of Right‐to‐Left Shunts: Utility of Submandibular Internal Carotid Artery Recording

Cardiac right-to-left shunts (RLSs) can be detected by echocardiography and transcranial Doppler ultrasound (TCD). In patients without adequate transtemporal bone windows, results may be obtained by insonating extracranial arteries; however, the sensitivity and practicality of this approach is unknown. In 34 patients evaluated with echocardiography for RLSs, 73 studies were performed with unilateral, simultaneous contrast TCD (cTCD) of the middle cerebral artery (MCA) and anterior cerebral artery (ACA) and submandibular power M-mode Doppler (PMD) ultrasound of the extracranial internal carotid artery (ecICA). The number of microbubble (MB) signals and their times of first appearance were determined. RLS volume was graded on 6 levels (I = trace, II = small, III = medium, IVa = large, IVb = shower, IVc = curtain) and compared between MCA and ecICA recordings. In 2 of 24 cTCD studies in 15 patients without evidence of RLSs on single-gated MCA monitoring, low-volume RLSs (grades I and II) were detected via ecICA insonation; in both, MB signatures were tracked in the ecICA, passing into the ipsilateral ACA. In 40 of 49 studies (26 patients) in which RLSs were demonstrated with single-gated MCA monitoring, more MBs were detected in the ecICA than the MCA, with either single-gated or M-mode images, with increases of 76.9% and 66.1%, respectively (P = .027). Compared to single-gated studies, M-mode technology detected nonsignificant increases in MB number in both the MCA and the ecICA (by 20.2% and 14.0%, respectively). Contrast PMD with cervical ICA recording is at least as sensitive and specific as the traditional MCA method in detecting RLSs; furthermore, this method seems to be more sensitive for low-volume RLSs (grades I-III) because of air MB decay (9.2%) and entry into the ipsilateral ACA (34.2%). This is in concordance with the increase of detected RLS grades observed in 32.7% of patients with echocardiography-documented RLSs. The authors therefore suggest the incorporation of ecICA PMD not only in patients with poor ultrasonic bone windows but also in every patient being evaluated for suspected RLSs.

A new index, the core erosion ratio, of compression-coated timed-release tablets predicts the bioavailability of acetaminophen

Although compression-coated tablets are a commonly used timed-release drug delivery technology, their utility is often limited by poor bioavailability. To try to improve the bioavailability of these tablets, the effect of their core composition of compression-coated tablet on in vivo pharmacokinetics was investigated. First, the extent of mass reduction of cores in different compression-coated tablet core formulations was used to establish a new index, the core erosion ratio. The data show that adding excipients with high water solubility to the core results in a greater core erosion ratio. Next, to elucidate the effect of core erosion ratio on in vivo acetaminophen (AAP) release, three compression-coated tablet formulations with similar in vitro AAP release profiles but different core erosion ratios were administered to four fasted dogs. The time for first appearance (TFA) of AAP in plasma did not differ significantly among formulations, indicating that the in vivo lag time was the same for all formulations. In separate experiments, necroscopy revealed that 3 h after oral administration, the tablets were located in the ileum and colon and that all three formulations had identical GI transit times. However, the area under the AAP plasma concentration–time curve was greater in dogs given formulations with larger core erosion ratios. These results suggest that a formulation with a large core erosion ratio can significantly increase in vivo drug release from compression-coated tablets, leading to increased drug absorption from the lower GI tract.

41 Incidence of paralytic shellfish toxin in bivalve mollusc tissue from the oregon coast

Saxitoxin and domoic acid sequestration by bivalve molluscs occurs periodically along the Oregon coast, presumably as a result of harmful algal blooms (HABs). Since 1958 and more continuously since 1979, the Oregon Shellfish Program (OSP) has assayed toxin levels in these molluscs as part of a monitoring program for paralytic (PSP) and amnesic (ASP) shellfish poisoning. We have created a working data base for all PSP sampling by the OSP between 1958 and 2001 and have examined the data for spatial and temporal trends in the appearance of toxin in shellfish, amount of toxin, and apparent duration of toxic events. In this report, we examine the data from the five stations with the longest record of continuous sampling (1979–2000) for evidence of correlation with El Niño events, upwelling, and/or a pattern of increasing frequency or intensity of toxic events. We also compare the pattern of appearance of toxin at open coast stations with the timing of first appearance of toxin in shellfish at adjacent estuarine stations. This is an important analysis because, in Oregon, shellfish closures due to PSP occur frequently in mussel beds on the open coast and the source of toxin‐producing organisms is unknown.

Residence time distribution in a co-rotating, twin-screw continuous mixer by the step change method

Residence time distributions were determined for the continuous processing of chocolate in a twin-screw, co-rotating mixer, and modeled using as a series combination of piston flow and ideal mixing elements or as equal size tanks in series. Color ( L-value) was measured after a step change from milk chocolate to white chocolate. Both models fit the data well, although the series combination of piston flow and ideal mixing fit better for short mean residence times, accurately predicting the observed deadtime. The series of tanks model appeared to fit data better under conditions where longer mean residence times were observed. The mean residence time was significantly influenced by feed rate, screw speed and gate opening. A high shear, low conveyance screw configuration was used that led to a high fill fraction ( >0.85). Therefore, feed rate had the greatest effect on the mean residence time. The time of first appearance was affected only by the gate opening, and ranged from 0.44 to 0.68 times the mean residence time.

Maternally transmitted antibodies to pregnancy-associated variant antigens on the surface of erythrocytes infected with Plasmodium falciparum: relation to child susceptibility to malaria.

The consequences of pregnancy-associated malaria on a child's health have been poorly investigated. Malarial infection of the placenta seems to result in a higher susceptibility of children to the parasite during their first year of life. In 1993-1995, the authors investigated the role of antibodies in variable surface antigens (VSA) specific to chondroitin sulfate A (CSA)-binding parasites to assess the parasitologic status of the child. Flow cytometry was used to measure levels of antibodies to VSA from CSA-selected and -unselected parasite lines in the cord blood of 79 newborns in Ebolowa, Cameroon. These newborns were subsequently followed up for 2 years to determine the date of first occurrence of blood parasites and mean parasite density during follow-up. Maternally transmitted antibodies to VSA expressed by CSA-binding parasites, but not antibodies to any other specificity, were negatively related to time of first appearance of Plasmodium falciparum in a child's blood and were positively related to mean parasite density during the first 2 years of life. If maternal infection is thought to be the main mechanism influencing susceptibility of the newborn to malaria, antibodies to VSA may better denote maternal malaria infection during almost the entire pregnancy as opposed to placental blood smear reflecting infection during the last few months of pregnancy.

Oral mucosa alterations induced by cyclosporin in mice: morphological features

The mechanisms involved in the pathogenesis of cyclosporin A-induced gingival hyperplasia are not well understood. The present work aimed at developing a mouse model with the characteristics of the human process, i.e. time of appearance, dose dependency and the capacity of developing in a variety of genetic backgrounds. This model would present the advantages of using a very well known animal species, small and easy to handle, with a number of experimental reagents (antibodies, etc.) already available against its products. Three different strains of mice were used: CBA, F1(C57Bl x DBA), Balb/c. Groups of mice received different concentrations of cyclosporin A (CSA) (10 mg/kg, 25 mg/kg and 40 mg/kg body weight) intraperitoneally five times a week. Anatomical and histological alterations were recorded at various time intervals. All strains of mice presented gingival hyperplasia after 8 weeks of CSA treatment. A dose-dependency was observed with regard to the time of first appearance of alterations. Increased redness was seen in all animals at the sixth week, independent of the dosage used. Histologic examination exhibited increased vascularization, epithelial and connective tissue thickening, edema and a mononuclear infiltrate. It was possible to develop CSA-induced gingival hyperplasia in mice with the characteristics described in humans and other species. The use of this animal model may help in the elucidation of the process involved in CSA-induced gingival overgrowth.

Digesta passage and fiber digestibility in captive white-faced sakis (Pithecia pithecia).

Wild white-faced sakis (Pithecia pithecia) ingest primarily seeds that provide a diet that is lipid-rich and moderately high in dietary fiber. Although little anatomical information is available on sakis, evidence from other vertebrate seed predators suggests that such a diet is correlated with adaptations in gut morphology or physiology. Milton [1984] reported a 20 hr transit time (TT=transit time or time of first appearance in feces) of a particulate marker for a single monk saki (Pithecia monachus). This suggests that TT for Pithecia sakis may be four to five times longer than what has been reported for soft-fruit-eating platyrrhines, such as Ateles and Cebus. During a captive study, we calculated an average TT of 14.7+/-0.4 hr (n=5 trials started in the evening) for a chromic oxide (Cr(2)O(3)) marker that follows liquid digesta and TTs of 14.5 hr (trial started the previous evening) and 23.0 hr (trial started the previous morning) for two trials using particulate markers. Mean retention time (MRT) for the liquid marker ranged from 15.3 hr to 37.7 hr in four trials that lasted longer than 90 hr. Marker recovery was incomplete for the particulate markers in these trials, and thus MRT could only be determined for the liquid phase marker. Three 5-day trials on a low-fiber, blended diet revealed high fiber fraction digestibilities (neutral detergent fiber (NDF)=77.4% and acid detergent fiber (ADF)=74.4%). Data collected for this study and nutritional data from wild sakis suggest that pitheciin seed predators may have a potential for fiber digestibility that is intermediate between ripe-pulp frugivores and folivores.

Performance of different strains of &lt;i&gt;Pleurotus&lt;/i&gt; species under Ghanaian conditions

The spawn run period, time for first appearance of mushrooms, number of flushes and biological efficiency (yield) of eight different strains of oyster mushrooms grown on composted sawdust of Triplochiton scleroxylon K (Schum) were studied. The spawn run period on the compost bags for the strains ranged from 40-48 days. Plewotus citrinopileatus strain PCB showed very poor and patchy growth and the mycelium never fully colonised the substrate. This indicates that the different strains of the mushrooms utilize the given substrate at different rates. The time for first appearance of mushrooms ranged from 4 to 35 days. With the exception of P. burundii strain HK-51, which produced only one flush, all strains produced at least three flushes. Pleurotus eous strain Kapak, the highest yielding strain produced six flushes. With all the strains flush 1 gave the highest yield of 63.9g, and flush 6 the lowest yield of 0.9g. Pleurotus eous strain Kapak gave the best yield and biological efficiency whilst P. burundii strain HK-51 produced the least yield. P. citrinopileatus strain PCB did not produce any fruiting bodies during the period of study. Significant differences (P

Novel method to assess gastric emptying in humans: the Pellet Gastric Emptying Test

To further validate the Pellet Gastric Emptying Test (PGET) as a marker of gastric emptying, a randomized, four-way crossover study was conducted with 12 healthy subjects. The study consisted of oral co-administration of enteric coated caffeine (CAFF) and acetaminophen (APAP) pellets in four treatment phases: Same Size (100 kcal), Fasted, Small Liquid Meal (100 kcal), and Standard Meal (847 kcal). The time of first appearance of measurable drug marker in plasma, t initial, was taken as the emptying time for the markers. Co-administration of same size enteric coated pellets of CAFF and APAP (0.7 mm in diameter) revealed no statistically significant differences in t initial values indicating that emptying was dependent only on size and not on chemical make-up of the pellets. Co-administration of different size pellets indicated that the smaller 0.7-mm diameter (CAFF) pellets were emptied and absorbed significantly earlier than the larger 3.6-mm diameter (APAP) pellets with both the Small Liquid Meal (by 35 min) and the Standard Meal (by 33 min) ( P<0.05). The differences in emptying of the pellets were not significant in the Fasted Phase. The results suggest that the pellet gastric emptying test could prove useful in monitoring changes in transit times in the fasted and fed states and their impact on drug absorption.