Biological discrimination between calcium and strontium in kidneys and bone of young and adult rats

Effects of aging on the biological discrimination between calcium (Ca) and strontium (Sr) by the kidneys and bone were studied in male and female rats of 5 to 50 wk of age by examining Sr/Ca ratios in the plasma, urine, and bone. The Ca-Sr discrimination at the reabsorption process in the kidneys was not affected by aging in male or female rats. On the other hand, discrimination between the two elements was shown to be age-related at the absorption process in the digestive tract, and became more strict with age. The reverse situation was observed in the discrimination of Ca and Sr in the femur; younger rats discriminated the two elements more strictly than older animals.     

A new fluorometric assay method for quinolinic acid

A new fluorometric assay method for quinolinic acid is introduced in this study. Quinolinic acid-hydrazine complex, a stable fluorescent compound, is formed after heating quinolinic acid with hydrazine at 215–220°C for 2 min. Fluorescence excitation and emission maxima of the complex are at 285 and 380 nm, respectively. This assay method is rapid and rather sensitive. It takes about 30 min to ascertain the amount of quinolinic acid as low as 50 ng. Specificity of this method is high among biological compounds. An ultrasensitive assay method for uinolinic acid (as low as 20 pg) with diphenylhydrazine instead of hydrazine is also found. After separating the quinolinic acid-diphenylhydrazine complex from residual diphenylhydrazine, this ultrasensitive assay method may be practically applicable.     

High-resolution proton magnetic resonance spectra of muscle

High-resolution proton magnetic resonance spectra of intact muscles of frog and rat were obtained with selective saturation of the water signal. The spectra consisted of the superposition of a broad component and a high-resolution portion. The line width of the former was about 5 ppm and is assumed to originate from the protons of the macromolecules in muscle. The high-resolution portion showed well-resolved signals arising from creatine phosphate, creatine, carnosine, lactate and lipids. It is suggested that this technique could be used to monitor the intracellular pH by measuring the chemical shift of carnosine and the lipid consumption due to muscular contraction. When the spectrum of ³¹P-NMR is prepared simultaneously, the ratio of creatine phosphate to total creatine can also be determined.     

Factors Influencing the Establishment of Persistent Infection of HVJ (Sendai Virus) in L Cells

Infection of a subline of L cells adapted to grow in suspension (Ls) with Fushimi strain of HVJ (HVJ-F) resulted in a virus carrier state. Ls cells, when cultured in monolayer, showed morphological changes following infection of HVJ-F and were detached from the glass wall. However, when the detached cells were transferred to a new environment of suspension culture within 5 days after infection, the carrier state was again established. HVJ-F caused only lethal infection in L cells maintained exclusively in monolayer (Lm). On the other hand, both Ls and Lm, irrespective of their culture conditions, were lethally infected by Nagoya 1–60 strain of HVJ. The overall results showed that culture condition as well as the kind of host cells or virus strains is an important factor regulating the establishment and maintenance of the virus carrier state.     

Target-selective cytotoxicity of methotrexate conjugated with monoclonal anti-MM46 antibody

Summary In studies on antitumor antibody-cytotoxic drug conjugates as potential tumor-selective cytotoxic agents, methotrexate (MTX) was conjugated via its active ester derivative with a murine monoclonal antibody (aMM46) to a mouse mammary tumor antigen (MM antigen) on syngeneic, ascitic C3H/He mouse mammary tumor MM46 cells. The conjugate retained full antibody activity, as assayed by complement-dependent cytolysis. The target-selective cytotoxicity of aMM46-MTX was verified by the observations that this conjugate showed greater cytotoxicity than the corresponding normal mouse immunoglobulin (nIg) conjugate to MM46 cells, neither aMM46 nor nIg being cytotoxic, and that it showed less cytotoxicity to MM antigen negative mouse mammary tumor MM48 cells than to MM46 cells, its cytotoxicity to MM48 cells being similar to that of the nIg conjugate. From the results of assays of cell binding and uptake of ¹³¹I-labeled aMM46 and aMM46-³H-MTX, aMM46 and aMM46-MTX were internalized after their binding to MM46 cell surface antigen. Leupeptin, an inhibitor of the lysosomal endopeptidase cathepsin, decreased the cytotoxicity of aMM46-MTX, supporting the involvement of lysosomal degradation of the conjugate in its action.     

The feeding from edge towards inner part in soybean plot in rufous turtle dove,Streptopellia orientalis (Latham) and the estimation of passing rate of the flock

Rufous turtle dove, Streptopelia orientalis, coming to the soybean field entered it from the outer part to eat soybean cotyledons. As a result, the injured plants extended from the outer to inner parts in the field. A model expressing these behaviours was constructed here, by assuming that the amount of food birds can eat in one block determines whether they stay there or move into neighbour block. As the food decrease due to exploitation of them by birds, birds enter into farther parts with the passage of time. The rate of feeding in all visiting birds (an₀ where a is the rate of feeding per individual and n₀ the number of birds visiting) and the rate of staying at a block, b, was estimated from the field experimental results, using the above model. The value of an₀ fluctuated greatly, depending upon the season in which soybean seeds sowed. The value of b also fluctuated inversely with that of an₀, suggesting the the staying rate decreases with an increase in the number of doves coming, probably because of interference among individuals.     

trans-cinnamic acid 4-hydroxylase of Phaseolus mungo: A new assay method

A simple and sensitive method for the assay of trans-cinnamic acid 4-hydroxylase by use of tritiated substrate is described. This method is based on the migration of tritium during the enzyme-catalyzed hydroxylation. The hydroxylase activity is detected in microsomes from Phaseolus mungo. The tritium method can be used practically with sensitivity similar to that of the ¹⁴C method. In view of the time and labor required the tritium method is obviously more advantageous.