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At least 1,495 records · Page 83Linked to original sources
PubMed2006

Intracolony variation of bacterial gut microbiota among castes and ages in the fungus-growing termite Macrotermes gilvus.

The fungus-growing termites Macrotermes cultivate the obligate ectosymbiontic fungi, Termitomyces. While their relationship has been extesively studied, little is known about the gut bacterial symbionts, which also presumably play a crucial role for the nutrition of the termite host. In this study, we investigated the bacterial gut microbiota in two colonies of Macrotermes gilvus, and compared the diversity and community structure of bacteria among nine termite morphotypes, differing in caste and/or age, using terminal restriction fragment length polymorphism (T-RFLP) and clonal analysis of 16S rRNA. The obtained molecular community profiles clustered by termite morphotype rather than by colony, and the clustering pattern was clearly more related to a difference in age than to caste. Thus, we suggest that the bacterial gut microbiota change in relation to the food of the termite, which comprises fallen leaves and the fungus nodules of Termitomyces in young workers, and leaves degraded by the fungi, in old workers. Despite these intracolony variations in bacterial gut microbiota, their T-RFLP profiles formed a distinct cluster against those of the fungus garden, adjacent soil and guts of sympatric wood-feeding termites, implying a consistency and uniqueness of gut microbiota in M. gilvus. Since many bacterial phylotypes from M. gilvus formed monophyletic clusters with those from distantly related termite species, we suggest that gut bacteria have co-evolved with the termite host and form a microbiota specific to a termite taxonomic and/or feeding group, and furthermore, to caste and age within a termite species.

Age Factors↗
PubMed2005

Hair casts due to a deodorant spray.

A 7-year-old girl presented with itching and greyish-white sleeve-like structures in her hair. After ruling out other possible causes for the symptoms, such as nits and dandruff, it was determined that the patient was affected by hair casts. These are small cylindrical structures resembling louse eggs that encircle individual scalp hairs and are easily movable along the hair shafts. It was concluded that she had induced the condition through misuse of a deodorant body spray. Scanning electron microscopy combined with electron dispersive X-ray analysis (X-ray microanalysis) of the hair casts showed the chemical nature of the structures. Some elements present in the composition of the ingredients of the deodorant spray, such as aluminium, chlorine, silicon, magnesium and carbon, were also present in this uncommon type of hair casts.

Antiperspirants↗
PubMed2001

A comparative study of intraplacental villous arteries by latex cast model in vitro and color Doppler flow imaging in vivo.

OBJECTIVE: The purpose of this study was to determine whether color Doppler sonogram can accurately depict the placental vascular structures using a latex cast model of the placental vessels, and to make a nomogram of several blood flow parameters according to the vascular structures. METHODS: First, we made 9 latex cast models of placental arteries and performed morphologic observation and measurement. Second, the comparative anatomical observation of placental vessels by color flow mapping was performed for all 9 patients from whom the latex models were made. Third, a total of 102 uncomplicated pregnant women between 18 and 40 weeks gestation were examined by color Doppler imaging. The resistance indices (RI) and peak systolic velocity (PSV) were measured. RESULTS: In the latex cast model of placentas, cotyledons could be differentiated by the presence of independent vascular structure units. First, second, third and fourth branches were noted in one cotyledon. Cotyledons were easily identified and counted by color Doppler imaging. Each cotyledon contained only one first branch of the intraplacental villous artery (IPVA). The number of IPVA-1 on color Doppler imaging was equal to the number of the cotyledon calculated from the latex model. RI exhibited a negative, and PSV a positive correlation with gestational age (p < 0.05 in both cases). At any given gestational age, both RI and PSV in the peripheral arteries were significantly lower (p < 0.01) than those in the upstream arteries. CONCLUSIONS: Color Doppler flow sonography is a valuable tool for detecting the blood flow of intraplacental villous arteries in vivo and the images agree with the vascular anatomy of placenta in vitro. These results may also provide the basic parameters for future studies of some complicated pregnancies.

Adolescent↗
PubMed1994

The effect of tooth preparation on retention and microleakage of cemented cast posts.

PURPOSE: Vibration from the high-speed handpiece may adversely affect the cement layer between a casting and a tooth, causing loss of retention or increased microleakage. This study assessed the effect of crown preparation on retention and microleakage of cemented cast post and cores. MATERIALS AND METHODS: Post and cores were fabricated for extracted teeth and cemented. Specimens were prepared for crown restorations, varying the preparation time and the rotary diamond instrument used. After thermocycling and immersion in a dye bath, tensile unseating force and linear dye penetration were measured. RESULTS: In general, retention decreased with increased severity of crown preparation; however, differences were not statistically significant (alpha = .05). Although the differing preparation conditions resulted in significant differences in microleakage, no consistent trends were evident. CONCLUSIONS: Crown preparation using high-speed rotary diamond abrasives of cast post and cores luted with zinc phosphate cement had no significant effect on their retention, but had varying effects on subsequent microleakage at the cement-tooth interface.

Analysis of Variance↗
PubMedDate not supplied

Laser welding of cast titanium and dental alloys using argon shielding.

PURPOSE: This study investigated the effect of argon gas shielding on the strengths of laser-welded cast Ti and Ti-6Al-7Nb and compared the results to those of two dental casting alloys. MATERIALS AND METHODS: Cast plates of Ti, Ti-6Al-7Nb, gold, and Co-Cr alloy were prepared. After polishing the surfaces to be welded, two plates were abutted and welded using Nd:YAG laser at a pulse duration of 10 ms, spot diameter of 1 mm, and voltage of 200 V. Five specimens were prepared for each metal by bilaterally welding them with three or five spots either with or without argon shielding. The failure load and percent elongation were measured at a crosshead speed of 1.0 mm/min. RESULTS: The factor of argon shielding significantly affected the failure load and elongation of the laser-welded specimens. The failure loads of argon-shielded laser-welded CP Ti and Ti-6Al-7Nb were greater compared with the failure loads of specimens welded without argon shielding for both three- and five-spot welding. Regardless of argon shielding, the failure loads of the laser-welded gold alloy were approximately half that of the control specimens. In contrast, the failure loads of the nonshielded laser-welded Co-Cr alloy were greater. The percent elongations positively correlated with the failure loads. CONCLUSIONS: The use of argon shielding is necessary for effective laser-welding of CP Ti and Ti-6Al-7Nb but not for gold and Co-Cr alloy.

Analysis of Variance↗
PubMed2004

Reproducibility and accuracy of automated probe measurements of gingiva and bone levels on stone casts following guided bone regeneration treatment.

OBJECTIVES: For evidence-based evaluation of guided bone regeneration (GBR), accurate registration of changes in gingiva and bone levels is needed. A new method is introduced and evaluated. METHODS: In a clinical trial with 30 patients, alginate impressions of the surgical area including the interproximal gingiva and alveolar bone at the adjacent teeth were made in duplicate prior to and during GBR surgery, fixture installation and abutment connection. Poured in hard stone, the casts were used for repeated measurements of the level of the free gingival margin and the alveolar bone with an automated probe (Florida disc-probe(R)), using the incisal edge as a fixed reference point. The reproducibility and accuracy of these measurements were evaluated by means of the Intraclass Correlation Coefficients and Generalizability Theory. The effect of treatment was evaluated by multivariate analysis of variance. RESULTS: Generalizability Theory indicated a high accuracy of the gingiva- and bone-level measurements: the Intraclass Correlation Coefficients for gingiva and bone levels were 0.99 and 0.98, respectively. The intra-cast reproducibility was 0.09+/-0.07 mm (mean+/-SD) and the inter-cast reproducibility was 0.10+/-0.09 and 0.20+/-0.07 mm for gingiva and bone levels, respectively. Clinical applicability is demonstrated by the fact that manova revealed on average a small but highly significant (p=0.001) effect of the staged surgical intervention on the gingiva and bone levels at the adjacent teeth. CONCLUSION: It is concluded that the presented method makes it possible to evaluate reproducibly and accurately changes in gingiva and bone levels for GBR studies.

Alveolar Bone Loss↗
PubMed2004

Retrospective clinical evaluation of 1,314 cast gold restorations in service from 1 to 52 years.

A retrospective clinical evaluation of 1,314 cast gold restorations in 114 patients placed by one practitioner was conducted. A very high percentage of patients contacted (114/116 [98.3%]) participated in the evaluation. Almost 90% of the restorations had been in service for over 9 years, 72% for over 20 years, and 45% from 25 to 52 years. All restorations had been cemented using zinc phosphate cement. The restorations were evaluated by independent evaluators in terms of marginal integrity, anatomic form, and surface texture, and 96% of the evaluations were excellent (Figures 1-5). Sixty restorations required removal and replacement, yielding an overall failure rate of 4.6% or a survival rate of 95.4%. The survival rates at various time periods were 97% at 9 years, 90.3% at 20 years, 94.9% at 25 years, 98% at 29 years, 96.9% at 39 years, and 94.1% for restorations in place > 40 years. It appears that properly fabricated cast gold inlays, onlays, partial veneer crowns, and full veneer crowns can provide extremely predictable, long-term restorative service. It is suggested that the use of such restorations should not be automatically precluded simply because they are gold colored. These restorations should be considered in patients who are more concerned with longevity than esthetics, and in those patients in whom placement of a conservative cast gold restoration would not result in an unesthetic display of metal.

Adult↗
PubMed1996

Flow measurements in an aortocoronary bypass graft casting.

Flow visualization and pressure measurements were carried out in a singel valve saphenous vein casting which was made from a saphenous vein segment obtained from a bypass patient at Cedars Sinai Medical Center. Dye was injected to understand the flow around the valve. The dye showed very complex flow patterns around the valve and in the valve sinus, and the cavity formed by a ligated branch. For steady flow, pressure drops across the valve were 0.72, 2.0 and 6.3 mmHg for the physiological flow rates of 45, 84, and 169 ml/min, respectively. Overall pressure drop across the casting (compared to Poiseuille flow for a straight tube) increased with the flow rate, being 130 to 290 percent higher over this flow rate range. In the case of pulsatile flow, pressure drops across the valve were 0.95 and 3.0 mmHg for the flow rates of 47 and 87 ml/min which were 26 and 43 percent higher than those of steady flow. Overall pressure drop was 220 and 360 percent higher for those flow rates compared to Poiseuille flow. The measured spatial pressure distributions along the casting and flow visualization indicated the global nature of the flow field with the accelerated flow through the valve separating and reattaching downstream along the wall in the pressure recovery region. Atherosclerosis may be prone to occur in the lower shear region along the wall beyond the valve tip in the reattachment region, as we have observed in vivo in rabbit experiments.

Biomechanical Phenomena↗
PubMed1992

Flow measurements in a highly curved atherosclerotic coronary artery cast of man.

Flow visualization and wall pressure measurements were made in a polyurethane cast of a cadaver coronary artery with a significant "s" shaped reverse curvature. A sucrose solution was used to simulate the kinematic viscosity of blood, with flow rates in the physiologic range. Flow visualization demonstrated significant secondary flow patterns in the wall vicinity, which increased with increasing Reynolds number. Random dye dispersion was observed at a Reynolds number of about 400, but not at 200. Dye filament patterns in the transition between the first and second curved region were predominantly influenced by the second curved region at lower Reynolds numbers, and by the first curved region at higher Re. Local wall pressure measurements demonstrated a significant centrifugal effect with large radial pressure differences across the casting. Flow resistances for the casting were considerably greater than reference Poiseuille flow values, and increased further with pulsatile flow.

Blood Pressure↗
PubMed1981

Correlation of human arterial morphology with hemodynamic measurements in arterial casts.

A realistic pulsatile flow was passed through a cast of the aortic bifurcation of a 63-yr-old male with mild atherosclerosis, and a laser Doppler anemometer was used to measure fluid velocities in the cast at 15 selected sites near the lateral and medial walls. Intimal, medial and adventitial thicknesses were measured and sudanophilia was scored at corresponding sites in the vessel from which the cast had been made. A negative correlation was found between intimal thickness (IT) and wall shear rate. The strongest negative correlation (p less than 0.005) was between IT and "pulse shear rate" (PSR), defined by analogy with pulse pressure. Sudanophilia also correlated negatively with PSR (p less than 0.01). Medial thickness correlated positively with shear rate, and most strongly with the mean (i.e., time-average) rate (p less than 0.005). From an analysis of the fluid mechanical data, it appears possible to separate the effects of bifurcation geometry and the shape of the arterial cross section on interfacial shear.

Aorta↗
PubMed1986

Measurement of wall motion and wall shear in a compliant arterial cast.

Initial measurements of the time-varying wall shear rate at two sites in a compliant cast of a human aortic bifurcation are presented. The shear rates were derived from flow velocities measured by laser Doppler velocimetry (LDV) near the moving walls of the cast. To derive these shear rate values, the distance from the velocimeter sampling volume to the cast wall must be known. The time variation of this distance was obtained from LDV measurements of the velocity of the wall itself.

Aorta↗
PubMed1991

Cyclic amplification and selection of targets (CASTing) for the myogenin consensus binding site.

The consensus binding site for the muscle regulatory factor myogenin was determined from an unbiased set of degenerate oligonucleotides using CASTing (cyclic amplification and selection of targets). Stretches of totally random sequence flanked by polymerase chain reaction priming sequences were mixed with purified myogenin or myotube nuclear extracts, DNA-protein complexes were immunoprecipitated with an antimyogenin antibody, and the DNA was amplified by polymerase chain reaction. Specific binding was obtained after four to six cycles of CASTing. The population of selected binding sites was then cloned, and a consensus was determined from sequencing individual isolates. Starting from a pool with 14 random bases, purified myogenin yielded a consensus binding site of AACAG[T/C]TGTT, while nuclear extracts retrieved the sequence TTGCACCTGTTNNTT from a pool containing 35 random bases. The latter sequence is consistent with that predicted from combining an E12/E47 half-site (N[not T]CAC) with the purified myogenin half-site ([T/C] TGTT). The presence of paired E boxes in many of the sequences isolated following CASTing with nuclear extracts proves that myogenin can bind cooperatively with other E-box-binding factors.

Animals↗
PubMed1978

Measurement of left ventricular cast volume by computed tomography.

Angiocardiographic methods available for cardiac-chamber volume measurements are neither consistently accurate nor precise. To explore the capability of computed tomography for left ventricular volume measurement, Silastic casts of 24 normal human left ventricles were measured by a displacement method, a conventional angiocardiographic biplane volume method, and computed tomography. The displacement method used degassing to remove air trapped in the casts; displacement was measured by Archimedes' principle. Cast volumes measured by biplane methods displayed spread around the regression line, caused by the chamber's irregular shape and its variations in orientation. Computed tomographic measurements were independent of chamber orientation and significantly more accurate.

Angiocardiography↗
PubMed1994

Right atrial MR imaging studies of cadaveric atrial casts and comparison with right and left atrial volumes and function in healthy subjects.

PURPOSE: To assess magnetic resonance (MR) imaging of the right atrium by measuring volumes of right atrial casts and determining right atrial volume cycles in healthy subjects. MATERIALS AND METHODS: Fourteen human cadaveric atrial casts were imaged and right atrial volumes of eight subjects were measured with cardiac-gated cine MR. Volumes were calculated and right and left atrial volumes were compared. RESULTS: Measured volumes of right atrial casts correlated well (r = .99, P < .001) with true volumes with a small underestimation noted (-7.2 mL +/- 2.3 [standard deviation], P < .001). The maximum in vivo right atrial volume averaged 77 mL/m2 +/- 11 of body area. The right atrial reservoir and conduit functions accounted for, on average, 58% and 19%, respectively, of the ventricular stroke volume; the remaining 23% came from atrial contraction. Right-to-left peak volume ratio averaged 1.41 +/- 0.15 (P < .001), and all volume measurements except conduit volumes were statistically significantly larger in the right atrium than the left. CONCLUSIONS: MR imaging provides a reliable means to study right atrial volumes and phasic function.

Adult↗
PubMed1993

Determination of left atrial volume using sonomicrometry: a cast validation study.

We developed a technique for left atrial (LA) volume estimation using two pairs of sonomicrometers sewn to the anteroposterior (LAX) and mediolateral (SAX) LA diameters and validated the method against water displacement of LA casts in 15 dogs. LA pressure was adjusted to a preselected level (5, 10, or 15 mmHg) by dextran infusion and was matched by postmortem infusion of casting resin (Conthane DPEN-18402). LA volume was modeled empirically as an ellipsoid of revolution without regression constants [(SAX)2(LAX)]. There was a strong correlation between the calculated LA volume and water displacement of the LA body [r = 0.87, standard error of estimate (SEE) = 3.3 ml, P = 0.0001] but a weaker correlation against water displacement of the entire LA (body+appendage, r = 0.81, SEE = 3.9 ml, P = 0.0003). The appendage volume fraction (appendage volume/total LA volume), as determined by water displacement of the casts, increased with increasing LA size (r = 0.78, P = 0.001). These data indicate that, in the normal canine heart, LA volume can be estimated accurately with high temporal and spatial resolution sonomicrometry using two atrial dimensions, and the contribution of appendage to total LA volume may become significant as the atrium enlarges.

Animals↗
PubMed1982

Interaction of oscillatory and unidirectional flows in straight tubes and an airway cast.

Because oscillatory resistance of the respiratory system is often measured during tidal breathing, we studied the interaction between simultaneous oscillatory and unidirectional flows in three straight tubes (radius ranging from 0.3025 to 0.679 cm and length either 30.7 or 173 cm) and a central airway cast (tracheal radius 0.685 cm). Oscillatory flow was generated by a loudspeaker, airway pressure was measured with a transducer, and flow was calculated from pressure changes in an airtight enclosure mounted behind the flow source (loudspeaker plethysmograph). Oscillatory resistance, i.e., the real part of impedance, was determined from 2 to 64 Hz. In the absence of unidirectional flow, frequency dependence of resistance was observed for the two 30.7-cm-long tubes to match previously published theory. Frequency dependence of resistance for the airway cast was similar to that of the tube of comparable inlet radius. In the presence of unidirectional flow, oscillatory resistance at low frequency was independent of frequency and determined by the magnitude of the unidirectional flow. Oscillatory resistance at high frequency was frequency dependent but still influenced by the magnitude of the unidirectional flow. Our results indicate that the presence of unidirectional flow alters the oscillatory resistance of tubes and the cast at any given frequency, presumably by changing the shape of the boundary layer.

Airway Resistance↗
PubMed2002

Castes, migration, immunogenetics and infectious diseases in south India.

It has been said that the grandest genetic experiment of nature has been conducted in south India in the name of the caste system. One can expect the frequency of an infectious disease to be equal to the product of the frequencies of various indicated loci/alleles, whether physiological, hormonal or immunological, in an endemic area. The sympatrically isolated caste and sub-caste populations of southern India, with differing origins, migration patterns and breeding habits, differ significantly in their HLA and other immune repertoire and are ideal models to study and test this hypothesis. The prevalence of a number of major infectious diseases, including TB and leprosy, are reviewed in different communities in the light of their genetic history.

Journal Article↗
PubMed1987

Mechanism of penile erection in the dog. Pressure-flow study combined with morphological observation of vascular casts.

A pressure-flow study of the corpus cavernosum penis in the dog was performed during the flaccid, tumescent, erect and rigid stages. Perfusion was selectively made into the penile deep artery. The erect stage was induced with the local administration of papaverine hydrochloride, and the rigid stage by electrostimulation of the ischiocavernous muscle during the erect stage. Concurrently, vascular casts of the penis at each stage of erection were observed under a scanning electron microscope for the anatomical analysis of the mechanisms controlling cavernous pressure. In the pressure-flow study, it was demonstrated that a combination of decreased arterial resistance and restricted venous outflow was essential to both cause and maintain the erect state. The rigid stage was generated by contraction of the ischiocavernous muscle tightly compressing the crus penis. In the rigid stage, the cavernous pressure was elevated as high as five times the perfusion pressure; nevertheless, no backflow from the cavernous sinus to the deep artery was recognized. By use of the casts, it was confirmed that venous outflow restriction in the erect and rigid stages was due to compression of the postcavernous venules and penetrating veins in the tunica albuginea. The deep artery was occluded in the tunica albuginea in the casts made during the rigid stage, suggesting that the backflow from the corpus cavernosum penis to the deep artery was prevented by this occlusion. Therefore, in the rigid stage, the arterial and venous occlusion isolated the cavernous sinus from the systemic circulation; this mechanism seems to account for the maintenance of the extremely high cavernous pressure.

Algorithms↗