Identiy of brain alcohol dehydrogenase with liver alcohol dehydrogenase

A method for obtaining electrophoretically homogeneous rat liver alcohol dehydrogenase (EC 1.1.1.1) at a specific activity of 2-2.5 mumol/min per mg of protein is presented. Anti-sera prepared against the purified enzyme inhibit alcohol dehydrogenase by up to 75% and cause precipitation of virtually all the enzyme. The antisera were shown by immunoelectrophoresis of a partially purified liver homogenate to be specifically directed against alcohol dehydrogenase and were used to demonstrate that the alcohol dehydrogenases of rat brain and liver share common antigens. The total activity of alcohol dehydrogenase in rat brain homogenates is normally quite low, with as much as 10% of the total activity attributable to the activity in the blood contained within the brain; in cases of severe liver damage (induced experimentally with carbon tetrachloride) this contribution may rise to as much as 60%.

Cartilage in hemophilic arthropathy. Ultrastructural and microanalytical studies

The presence of iron in articular cartilage was investigated in five human and two canine cases of factor VIII-deficiency hemophilic arthropathy. The lesions were mild in three cases. Advanced destruction of the cartilage was present in four cases, in one of which sufficient cartilage was preserved to permit recognition of hemosiderin in chondrocytes. The Fe was present in the form of siderosomes and ferritin granules free in the cytoplasm. Iron and phosphorus were demonstrated in the siderosomes by energy dispersion analysis of x-rays; but no Fe was identified by this means or by light or transmission electron microscopy in chondrocytes from the three subjects in an early stage of the disease or in the matrix from any of the seven subjects. The findings lend no support to the hypothesis that salt formation or chelation of Fe ions by matrix proteoglycans is responsible for destruction of cartilage in hemophilic or other chronic hemarthroses. A second, nonferruginous, bilirubin-like pigment (hematoidin) was present in the matrix at the surface of the cartilage in two specimens.

Permeability limitation in estimation of local brain blood flow with [14C]antipyrine

Influence of capillary permeability on local cerebral blood flow (LCBF) estimated by the autoradiograhpic diffusible-indicator method was analyzed by computer simulation. Its influence increases with increasing flow. With normal perfusion rates in gray matter, capillary permeability coefficient x surface area (PS value) must exceed 0.12 cm3-s(-1)-g(-1) for estimated LCBF to attain 95% of true values in all structures. In white matter, with its lower perfusion rates, the PS value must exceed 0.035 cm3-s(-1)-g(-1) for equivalent accuracy. [14C]antipyrine, widely used in the LCBF technique, has a PS value below these values and leads to undersestimation of LCBF. Experimental studies in cats in which LCBF was measured with either [14C]antipyrine or the freely diffusible, radioactive gas, [131I]trifluoroiodomethane, demonstrated consistently lower estimates of LCBF with [14C]antipyrine than with the gas; the deviations in the various cerebral structures approximated those predicted by the theoretical analyses. These results suggest that the uptake of [14C]antipyrine by cerebral tissues is diffusion limited as well as flow limited, and it therefore is not an ideal tracer for the autoradiographic LCBF technique.

Mapping of functional neural pathways by autoradiographic survey of local metabolic rate with (14C)deoxyglucose

An enzymatic preparation from human brain converts tryptamine to tryptoline (9H-1,2,3,4-tetrahydropyrido(3,4-b)indole) in the presence of 5-methyltetrahydrofolic acid. Similarly, N-methyltryptamine and 5-hydroxytryptamine yield 1-methyltryptoline and 5-hydroxytryptoline, respectively. Neither in vitro nor in vivo formation of these compounds by human tissues has been described.

Tissue sampling as a potential source of error in experimental studies of cartilage

Although it might seem trite to point out that tissue sampling is a potential source of experimental error, this survey disclosed that even experienced investigators in fact often work with cartilage that is contaminated by non-cartilaginous tissue of which they were unaware. Twenty-two specimens ranging from chick embryo sternum to bovine nasal septum were studied by serial sectioning. Eighteen of the 22 contained extraneous tissue comprising from 3 to 50% of the cross-sectional area. The impact of the contamination depends on the use being made of the material and probably is greatest in cell culture studies because chondrocytes and fibroblasts have large differences in population doubling time. Several approaches for minimizing the error are suggested by the findings. Histological examination of specimen material is thus a desirable quality control procedure in the design and interpretation of experiments on cartilage as well as other tissues.

Animal model: arthritis due to Mycoplasma in rats and swine

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The collagenous nature of amianthoid degeneration of human costal cartilage

Amianthoid (asbestoid) fibers in aging human costal cartilage are shown to be collagenous both by their electron microscopic appearance and solubilization by clostridial collagenase. The fibers differ morphologically from collagen of dermis, synovium, tendon, fibrocartilage and hyaline articular cartilage in dimension, contour and arrangement. They measure up to 1 mu in width, and their period length is 560 to 620 A. Their thickness, straightness and parallel organization suggest that amianthoid fibers are rigid. Their stability in the face of the preparative technics suggests that cohesive forces rather than spatial apposition through depletion of ground substance operate to hold the component fibrils together. These forces may or may not arise from covalent cross-links.