COMPARISON OF POROSITY-DEPTH RELATIONSHIPS OF SHALE AND SANDSTONE*

The rate of shale compaction or porosity reduction decreases with increase in burial or compaction. This may be caused by decreasing shale permeability and increasing water viscosity, thus decreasing rate of fluid expulsion with increasing compiction. For a given increase in overburden pressure, the pressure or stress applied to a given grain-to-grain contact area decreases with burial becaused the contact area increases with compaction and concomitant grain deformation. This may also cause the reduced rate of compaction with increase in burial. The above abservations may suggest that the shale compaction is primarily controlled by physical forces of sedimentary rocks. On the contrary, the rate of sandstone porosity reduction is known to be relatively constant throughout the burial diagenetic history in many regions provided ther was no significant secondary porosity developed by leaching and fracturing. For a given increase in overburden pressure, the grain-to-grain contact area. Yet, rate of porosity reduction for the sandstones is realtively constant, whether they are at a shallow or deep burial depth. This suggests that, for the sandstones, the physical forces have been of secondary importance in reducing the porosity. Chemical and mineralogical agents are believed to have been more significant in sandstones. Numerous regional petrographic studies confiirm the importance of diagenetic cements.     

Measurement of the repeat period of myelin sheath using ultrathin frozen sections

The myelin sheath of peripheral nerves was observed by transmission electron microscopy (TEM) using plastic-embedded sections and ultrathin frozen sections. Repeat distances of myelin sheaths were measured in high-powered electron micrographs. The ultrathin frozen sections showed a longer repeat distance than the plastic-embedded sections. The ultrathin frozen sections were thought to contain fewer artefacts, as they had not been subject to dehydration and embedding. It is known that broken myelin sheaths are often observed under conventional TEM. It is thought that these procedures cause contraction and partial destruction of the myelin sheath.     

Liquid/liquid optical waveguides using sheath flow as a new tool for liquid/liquid interfacial measurements

A liquid/liquid optical waveguide was constructed using a sheath flow. Since the refractive index of an organic solvent is generally higher than that of water (nD = 1.33), light introduced into the inner organic flow should proceed with total multi-reflection within the inner flow, so that the inner part of the sheath flow acts as the core of an optical waveguide. This sheath flow liquid/liquid optical waveguide was stable and showed no substantial background scattering. Moreover, it is applicable to both miscible and immiscible liquid/ liquid interfaces. Thus, it may become a new tool for studying liquid/liquid interfaces as well as for sensitive optical measurements.     

Antithrombotic effects in a rat model of aspirin-insensitive arterial thrombosis of desethyl KBT-3022, the main active metabolite of a new antiplatelet agent, KBT-3022

The antithrombotic effect of desethyl KBT-3022, which is the main active metabolite of the new antiplatelet agent, KBT-3022 (ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl] pyrrol-1-ylacetate; a cyclooxygenase inhibitor), was determined using a photochemically induced arterial thrombosis model in the rat femoral artery. Pretreatment with desethyl KBT-3022 (0.1, 0.3 and 1 mg/kg, i.v.) prolonged the time required to achieve thrombotic occlusion in the femoral artery and inhibited collagen-induced platelet aggregation in whole blood ex vivo, each in a dose-dependent manner. In all 6 rats used, particularly at the highest dose (1 mg/kg, i.v.) tested, cyclic variations in blood flow were hardly ever observed and complete cessation of blood flow did not occur during the 30-min observation time. BM-13505 (1, 3 and 10 mg/kg, i.v.), a thromboxane A2 receptor antagonist, also prolonged the time to occlusion, but cyclic variations in blood flow did occur. On the other hand, aspirin (10 and 30 mg/kg, i.v.) had little effect in terms of preventing thrombosis, although it inhibited collagen-induced platelet aggregation to the same extent as did desethyl KBT-3022. Desethyl KBT-3022 inhibited the thrombin-induced aggregation of washed platelets in a concentration-dependent manner (1-40 microM), whereas aspirin and BM-13505 did not. These findings suggest that the potent antithrombotic effect of desethyl KBT-3022 may be attributable in part to its additional ability to inhibit thrombin-induced platelet aggregation. Accordingly, thromboxane A2 and thrombin may be important thrombotic mediators in this rat model.     

Separation and quantification of corticosteroid-induced, bone and liver alkaline phosphatase isoenzymes in canine serum

Quantifying alkaline phosphatase (ALP) isoenzymes in canine serum would provide a useful index in a clinical laboratory. To achieve this goal, we tested a semi-automatic assay combining wheat germ lectin (WGL) precipitation and chemical inhibition of isoenzymes of the TNS gene with levamisole to quantify bone ALP (BALP) and corticosteroid-induced ALP (CALP), respectively. The liver ALP (LALP) isoenzyme was then calculated from the equation: TALP = BALP + LALP + CALP BALP, LALP and CALP standards from serum of puppies, bile-duct ligated dogs and dogs on 4.4 mg/kg/day prednisolone for 30 days, respectively, were used. The suitability of standard sera was tested by affinity electrophoresis. Levamisole (4.2 mM) inhibits 98% of BALP and LALP but only 42% CALP. Multiplying measured CALP by 1.8 gives the total CALP value in serum. WGL precipitated 92.3% BALP, 23.3% LALP and 26.8% heated CALP standards. These values were used to adjust precipitated ALP to obtain the exact levels of BALP. WGL was then tested on pooled serum standards in which the relative proportions of all the ALPs were known and controlled. BALP was adequately quantified except when LALP and CALP levels were extremely high. The assay was also applicable under conditions resulting in high ALP. Therefore, combining WGL and levamisole inhibition provides an adequate separation and quantification of canine ALP isoenzymes. The method has great potential for diagnostic use and should be tested further for routine implementation.     

Inhibition of a Porphyromonas gingivalis colonizing factor between Actinomyces viscosus ATCC 19246 by monoclonal antibodies against recombinant 40-kDa outer-membrane protein

1. Porphyromonas gingivalis, an important pathogen in human periodontal disease, aggregates with Actinomyces viscosus ATCC 19246. 2. Monoclonal antibodies (mAbs) against purified recombinant 40-kDa outer-membrane protein (r40-kDa, OMP) of P. gingivalis 381 inhibited its coaggregation with A. viscosus ATCC 19246 in a dose-dependent manner. 3. Five mAb clones against r40-kDa OMP were selected. The isotype of the five was IgG1. 4. Pg-ompA2 inhibited the coaggregation of several strains of P. gingivalis with A. viscosus ATCC 19246 cells.     

PHYSICAL CONSTRAINTS OF FAULTING IN A GOPRESSURED SEDIMENTARY BASIN*

On the basis of the triaxial stress concept, the tectonic stress required for faulting and sliding in a sedimentary basin can be estimated. The horizontal tectonicstress necessary for thrust faulting, for example, increases with depth from the surface to about 9,000 ft (2.7 km), and decreases below 9,000 ft (2.7 km), primarily because of a changing Poisson's ratio. Changing the vertical effective stress caused by generation of abnormal fluid pressure would also change the tectonic stress requirements for faulting. The internal friction of sedimentary rocks in the subsurface must be exceeded by the tectonic stress applied to the basin for faulting or sliding to take place. Estimates of the internal friction suggest that there is a high probability of faulting at depth if there are thick undercompacted and geopressured sections. Diapirs may also occur in such a physical environment. If the sedimentary rocks are normally compacted and the fluid pressure is hydrostatic from the surface to depth, on the other hand, the rocks are generally too rigid to cause any significant sliding. There would be very little chance of faulting and diapirism in such a case. The concepts developed in this paper may have a practical application in the under-standing of the physical conditions and constraints of faulting and diapirism in a relatively-young sedimentary basin with significant geopressuring at depth.     

The advantage of magnetic resonance imaging in diagnosis of cauda equina syndrome in dogs

Three dogs were evaluated in our study using magnetic resonance imaging (MRI) to reveal the anatomical deformity and the degree of the lesion of cauda equina. In all dogs, MRI revealed soft tissue, such as cauda equina, epidural fat, and intervertebral disc, at the lumbosacral region clearly without contrast medium. Our results suggest that MRI has some advantages in evaluating cauda equina syndrome in dogs.