Sequential Sieving Research Articles

Evaluation of Oat Kernel Size Uniformity

Oat (Avena sativa L.) kernel size uniformity is important to the oat milling industry because oat‐processing mills separate oats according to size to optimize dehulling efficiency. In this study, we compared two different approaches for analyzing oat kernel size uniformity, namely the sequential sieving of oat samples with a gradient of slotted sieve sizes and digital image analysis. Image analysis of size fractions provided evidence that sieving separated oat kernels according to their depth, whereas, digital image analysis measured kernel length and width, and derived a measure of the area of the oat kernel image. Samples identified by sieving with superior uniformity were those with greater proportions of large kernels. Histograms of oat kernel sizes derived from digital image analysis suggested oat kernel sizes were (within a genotype and location) composed of bimodal populations. A new statistical analysis allowed for the derivation of means and variances of each of these subpopulations, the numerical balance between the two subpopulations, and the extent of bimodality. Oat samples with lower levels of bimodality tended to be of higher test weight and groat percentage and thus, of better milling quality. Both methods appear satisfactory for evaluating oat kernel size uniformity, although the sequential sieving method is likely to be more useful to breeding programs because of its relative technical ease and simplicity.

THE EFFECT OF TREATMENT STRATEGY ON STONE COMMINUTION EFFICIENCY IN SHOCK WAVE LITHOTRIPSY

The comminution of kidney stones in shock wave lithotripsy (SWL) is a dose dependent process caused primarily by the combination of 2 fundamental mechanisms, namely stress waves and cavitation. The effect of treatment strategy with emphasis on enhancing the effect of stress waves or cavitation on stone comminution in SWL was investigated. Because vascular injury in SWL is also dose dependent, optimization of the treatment strategy may produce improved stone comminution with decreased tissue injury in SWL. Using an in vitro experiment system that mimics stone fragmentation in the renal pelvis spherical BegoStone (Bego USA, Smithfield, Rhode Island) phantoms (diameter 10 mm) were exposed to 1,500 shocks at a pulse repetition rate of 1 Hz in an unmodified HM-3 lithotripter (Dornier Medical Systems, Kennesaw, Georgia). The 3 treatment strategies used were increasing output voltage from 18 to 20 and then to 22 kV every 500 shocks with emphasis on enhancing the effect of cavitation on medium fragments (2 to 4 mm) at the final treatment stage, decreasing output voltage from 22 to 20 and then to 18 kV every 500 shocks with emphasis on enhancing the effect of stress waves on large fragments (greater than 4 mm) at the initial treatment stage and maintaining a constant output voltage at 20 kV, as typically used in SWL procedures. Following shock wave exposure the size distribution of fragments was determined by the sequential sieving method. In addition, pressure waveforms at lithotripter focus (F2) produced at different output settings were measured using a fiber optic probe hydrophone. The rate of stone comminution in SWL varied significantly in a dose dependent manner depending on the treatment strategies used. Specifically the comminution efficiencies produced by the 3 strategies after the initial 500 shocks were 30.7%, 59% and 41.9%, respectively. After 1,000 shocks the corresponding comminution efficiencies became similar (60.2%, 68.1% and 66.4%, respectively) with no statistically significant differences (p = 0.08). After 1,500 shocks the final comminution efficiency produced by the first strategy was 88.7%, which was better than the corresponding values of 81.2% and 83.5%, respectively, for the other 2 strategies. The difference between the final comminution efficiency of the first and second strategies was statistically significant (p = 0.005). Progressive increase in lithotripter output voltage can produce the best overall stone comminution in vitro.

Influence of Oat Kernel Size and Size Distributions on Test Weight

Test weight is one of the most important characteristics for evaluating grain quality in oats. This study evaluated the role of oat kernel size and size distributions on test weight. Oat kernel size was measured from digital image analysis, sequential sieving and mean kernel mass of original oat samples and their different size fractions. Data from ten genotypes and eight environments indicated that smaller sized kernel fractions derived by sieving had higher bulk density than those from the larger sized kernel fraction. The smaller kernels also had greater groat percentages, indicating greater kernel density in smaller size fractions. To investigate a possible packing effect of different kernel sizes on test weight, the summation of volumes of size fractions was compared with the volume of the original sample. Our results indicated no significant differences between the volumes of the original sample and the sum of the volumes of their size fractions. This indicated that oats of uniform size packed just as efficiently as a mixture of different size kernels. A similar experiment evaluating bulk densities of the different size fractions reached the same conclusion. These results indicate that the test weight drops observed in seed cleaning, where the smaller kernels are removed, are due to the removal of the most dense kernels in the sample, and not to a packing effect, where smaller kernels might fill in spaces between larger kernels.

Trichodina murmanica (Ciliophora) and Gyrodactylus pleuronecti (Monogenea) parasitizing hatchery‐reared winter flounder, Pseudopleuronectes americanus (Walbaum): effects on host growth and assessment of parasite interaction

Winter flounder, Pseudopleuronectes americanus, caught in Passamaquoddy Bay, New Brunswick, Canada, and held captive under crowded conditions, developed mixed infections of Trichodina murmanica Polyanski, 1955 (Ciliophora) and Gyrodactylus pleuronecti Cone, 1981 (Monogenea). A protocol involving sequential sieving was used to separate the two species of parasites and produce viable experimental baths. Replicate groups of juvenile, hatchery‐reared flounder received one of the following treatments: mixed bath of G. pleuronecti and T. murmanica, bath of G. pleuronecti, bath of T. murmanica or parasite‐free (controls). The abundance of both parasites correlated negatively with condition factor of the flounder (r=−0.354, P < 0.001 for Trichodina; r=–0.205, P < 0.05 for Gyrodactylus). During the periods of peak parasite abundance (1–2 weeks postinfection), the effect of the two parasite species was additive, as mean condition factor and the percentage change in weight were significantly lower (ANOVA, P < 0.05) among fish with mixed infections compared to single infections or controls. The most common signs of tissue pathology were increased density of epidermal mucous cells on the fins and macrovesicular lipidosis of the hepatocytes. After a significant decline in parasite infrapopulations (3 weeks postinfection), infected fish resumed normal growth, indicating the observed effects were somewhat reversible.

IN VITRO COMPARISON OF SHOCK WAVE LITHOTRIPSY MACHINES

We tested the hypothesis that shock wave lithotripsy machines vary in the ability to fragment stones to small size. Calcium oxalate monohydrate, calcium hydrogen phosphate dihydrate, cystine and magnesium ammonium phosphate hexahydrate calculi were fragmented in vitro with the 22 kV. Dornier HM3, section sign 20 kV. Storz Modulith SLX, parallel, 15.6 kV. Siemens Lithostar C, paragraph sign 24 kV. Medstone STS-T,** 26 kV. HealthTronics LithoTron 160,daggerdagger 20 kV. Dornier Doli section sign and 22.5 kV. Medispec Econolithdouble daggerdouble dagger lithotriptors. Stones were given 500 or 2,000 shocks, or the Food and Drug Administration limit. Post-lithotripsy fragment size was characterized using sequential sieves and compared. Stone mass was statistically similar in the cohorts (p >0.94). Fragment size decreased as the number of shocks increased when the machine and stone composition were constant. Magnesium ammonium phosphate hexahydrate calculi were completely fragmented by all devices. At Food and Drug Administration treatment limits the mean incidence per device of calcium hydrogen phosphate dihydrate, calcium oxalate monohydrate, cystine and magnesium ammonium phosphate hexahydrate stones rendered into fragments greater than 2 mm. was 0% for the HM3, Modulith SLX and Lithostar C, 10% for the STS-T, 3% for the LithoTron 160, 29% for the Doli and 18% for the Econolith (p = 0. 04); 0% for the HM3, Modulith SLX, Lithostar C, STS-T and LithoTron 160, 4% for the Doli and 9% for the Econolith (p = 0.15); 1% for the HM3, 0% for the Modulith SLX, 1% for the Lithostar C, 10% for the STS-T, 14% for the LithoTron 160, 3% for the Doli and 9% for the Econolith (p = 0.44); and 1% for the HM3, 0% for the Modulith SLX, 1% for the Lithostar C, 10% for the STS-T, 14% for the LithoTron 160, 3% for the Doli and 9% for the Econolith (p = 0.44), respectively. Shock wave lithotriptors vary in fragmentation ability. The HM3, Modulith SLX and Lithostar C machines yield smaller fragments than other machines.

Lipoprotein(a) stimulates growth of human mesangial cells and induces activation of phospholipase C via pertussis toxin-sensitive G proteins

Renal disease is commonly associated with hyperlipidemia and correlates with glomerular accumulation of atherogenic lipoproteins, for example, lipoprotein(a) [Lp(a)], and mesangial hypercellularity. Specific binding of Lp(a) to mesangial cells and induction of c-myc and c-fos expression has been demonstrated. Therefore, in this study, we investigated a possible growth stimulatory effect and mode of action of Lp(a) in human mesangial cells. Lp(a) was purified from the regenerate fluid of a dextran sulfate column-based low-density lipoprotein apheresis system. Human mesangial cells were isolated by a sequential sieving technique from patients undergoing tumor nephrectomy. DNA synthesis was measured by [3H]-thymidine incorporation. The intracellular calcium concentration ([Ca2+]i) was determined by Fura 2-fluorescence, and inositol 1,4,5-trisphosphate (1,4,5-IP3) concentration was measured by a radioreceptor assay. The data show that Lp(a) bound to the cells with a Kd of 17.0 micrograms/ml and increased DNA synthesis and cell proliferation. Lp(a) caused a rapid increase in 1,4,5-IP3 and [Ca2+]i via a pertussis toxin-sensitive mechanism. The phospholipase C (PLC) inhibitor U73122 abolished Lp(a)-induced cell proliferation. In contrast, vasopressin-induced increase in 1,4,5-IP3 and [Ca2+]i was pertussis toxin insensitive. This study revealed that Lp(a) stimulates growth of human mesangial cells. Lp(a)-induced signaling involves binding to a receptor and stimulation of PLC via Gi proteins. Stimulation of PLC appears to be essential for the growth stimulatory effect of Lp(a). Whether these effects of Lp(a) contribute to the pathophysiology of renal disease needs to be determined.

An improved test system for PCR-based specific detection of Echinococcus multilocularis eggs.

For the sensitive detection of eggs of Echinococcus multilocularis in fox faeces by PCR we have evaluated a method based on the previous concentration of helminth eggs by a combination of sequential sieving of faecal samples and flotation of the eggs in zinc chloride solution. The eggs were microscopically detected in the fractions retained in 40 and 20 microns mesh sieves. DNA of the taeniid eggs retained in the 20 microns sieve was obtained after alkaline lysis and PCR was performed using E. multilocularis species-specific primers. Compared to the parasitological findings after examination of the small intestines of the foxes, the specificity of the PCR was 100% (no false-positive result with 20 foxes free of E. multilocularis) and the sensitivity was 94% (33 positive results from total 35 foxes proven to be infected with E. multilocularis). Both false-negative results were obtained with faeces from foxes harbouring immature worms. Using faecal volumes between 2 and 20 ml, no inhibition of PCR was observed as was demonstrated by the amplification of size-modified target in parallel reactions. The tests were undertaken with fresh faeces stored in 70% ethanol, but egg detection by PCR was also possible after inactivation of eggs by freezing the faeces at -80 degrees C for one week or by incubation at +70 degrees C for 2 h.

Early increase in glomerular leucocyte number after a reduction in renal mass: implications for the pathogenesis of glomerulosclerosis.

1. Adult female Wistar rats underwent uninephrectomy (n = 8) through a flank incision, or a sham operation (n = 7). One to two weeks later the kidney was perfused in situ and glomeruli were isolated from cortical tissue by sequential sieving, and partially digested. Glomerular leucocytes were labelled with a mouse monoclonal antibody against leucocyte common antigen followed by a fluorescein-labelled anti-mouse immunoglobulin to allow counting. 2. In a further group of animals 24 h albumin excretion and glomerular size were measured 2 weeks after either uninephrectomy (n = 6) or sham operation (n = 6). 3. Glomerular leucocyte number was significantly increased in uninephrectomized animals (15.7 +/- 0.9 versus 8.9 +/- 0.4, P < 0.001), with some glomeruli having leucocyte numbers comparable with those seen in glomerulonephritis. 4. Albuminuria was not increased 2 weeks after uninephrectomy (233 +/- 35 versus 170 +/- 42 micrograms/24 h, not significant), and glomerular size was unchanged. Light microscopical appearance was normal. 5. An increase in glomerular leucocyte number is an early response in what was previously considered a non-immunological lesion. It precedes the development of renal scarring and may be important in the pathogenesis of this process.