The relationship of alkaline phosphatase, CaATPase, and phytase

Alkaline phosphatase, highly purified from bovine intestinal mucosa, has significant hydrolytic activity against phytate and CaATP. Phytase and CaATPase activities require quite different assay conditions than those which are optimal for conventional alkaline phosphatase substrates such as 4-nitrophenyl phosphate. We have used affinity chromatography and antibody recognition to demonstrate that the phytase and CaATPase activities are not due to contaminating enzymes, but are intrinsic activities of intestinal alkaline phosphatase. All of the phytase and CaATPase activities present in crude extracts of bovine intestinal mucosa can be accounted for by alkaline phosphatase. Apparently neither phytase nor CaATPase exist in this tissue as independent enzymes. Specific substrates which require assay conditions quite different from the conventional 4-nitrophenyl phosphate substrate may account for the physiological function of "alkaline phosphatase."

The cytotoxic and mutagenic effects of alkylating agents on human lymphoid cells are caused by different DNA lesions

The Burkitt's lymphoma cell line Raji has a Mex+ phenotype. It is more resistant to killing by alkylating agents than a sub line (Raji TK-) which is Mex-. A reduction in O6-methylguanine (O6MeG)-DNA methyltransferase can be brought about by growing Raji cells in the presence of free O6MeG. The depletion in enzyme activity is specific and reversible; removal of O6MeG from the medium results in the restoration of methyltransferase activity within 4 h. Raji cells, in which methyltransferase has been reduced by this treatment to below detectable levels, are not sensitised to killing by N-methyl-N'-nitro-N-nitrosoguanidine or the cross-linking nitrosoureas, 1,3-bis(2-chloroethyl)-1-nitrosourea and 1-(2-chloroethyl)-1-nitrosourea. This implies that adducts at the O6 atom of guanine in DNA are not potentially cytotoxic lesions. Secondly, it suggests that a defect other than the lack of methyltransferase is responsible for the sensitivity of Mex- cells to killing by alkylating agents.

Recovery of cyclic nucleotide regulation in protein-kinase-defective adrenal cells through somatic cell fusion

A mutant cell line (designated Kin-8), isolated from the Y1 mouse adrenocortical tumor cell line on the basis of its resistance to growth-inhibition by 8-bromoadenosine 3', 5'-monophosphate (8BrcAMP), was resistant to the steroidogenic effects of the cyclic nucleotide analog and did not round up in the presence of 8BrcAMP as did responsive Y1 adrenal cells. In Kin-8 cells, the mutation to cyclic nucleotide resistance was associated with a defective type 1 cAMP-dependent protein kinase activity, suggesting an obligatory role for the enzyme in the regulation of these adrenal functions. In this study, the Kin-8 mutant was fused with a rat glioma cell line (C6) in order to analyze the genetic behavior of the protein kinase mutation in somatic cell hybrids. The growth of C6 glial cells was inhibited by 8BrcAMP and its cAMP-dependent protein kinase responded normally to cAMP. In addition, C6 cells had no capacity for steroidogenesis nor did they round up when treated with 8BrcAMP. In Kin-8 X C6 hybrids, the protein kinase mutation seemed to behave recessively. The growth of hybrid cells was inhibited by 8BrcAMP and the protein kinase responded to cAMP over a normal range. Kin-8 X C6 hybrids, when treated with 8BrcAMP, exhibited steroidogenic activities which were greater than the activity measured in either fusion partner and which had lower ED50 values for 8BrcAMP. In addition, Kin-8 X C6 hybrids rounded up in the presence of 8BrcAMP, a morphologic change unlike that seen with either fusion partner. The effects of 8BrcAMP on the steroidogenic activity and morphology of Kin-8 X C6 hybrids was reminiscent of the effects of the cyclic nucleotide on cAMP-responsive, parental Y1 adrenal cells. These results suggest that cell fusion provided a normal cAMP-dependent protein kinase for Kin-8 cells and led to the recovery of a cAMP-responsive adrenal phenotype. type. These results provide additional evidence in support of an obligatory role for cAMP-dependent protein kinase in the regulation of adrenal steroidogenesis, cell division, and cell shape.

Quantitation of xanthurenic acid in rabbit serum using high performance liquid chromatography

Xanthurenic acid (XA) has been quantified in the serum of normal and vitamin B6-deficient rabbits using high performance liquid chromatography. The concentration of XA in the serum of normal and B6-deficient rabbits was 141 and 2275 ng/ml, respectively. The coefficient of variation for a series of dilutions of standard XA (3.9 to 1000 ng) ranged from 45.5% at the lower limit of the curve to 10.9% at the higher range of the curve. The minimum detectable level was 3.9 ng/ml. Serum samples spiked with reference XA exhibited a parallel dose response. The percentage recovery of XA from serum samples was 80.8%. The procedure, which requires 1 to 2 ml of serum, is sensitive and may be a useful tool for assessing B6 nutritional parameters as well as the physiological role of XA. It offers advantages over urinary procedures because it is more sensitive, more specific, and allows the study of blood levels of XA.

mRNA from mutant Y1 adrenal cells directs the synthesis of altered regulatory subunits of type 1 cAMP-dependent protein kinase

The molecular basis for altered cyclic AMP-dependent protein kinase activity was examined in three different mutant clones (Kin-1, Kin-7, and Kin-8) derived from the Y1 mouse adrenocortical cell line. Parental Y1 cells and the Kin mutants were labeled with L-[35S] methionine and the regulatory subunit of the type 1 cAMP-dependent protein kinase isozyme (RI) was immunoprecipitated from each clone with a specific guinea pig antiserum. When analyzed by electrophoresis on isoelectric focusing gels, the immunoprecipitates from mutant clones exhibited parental forms of RI plus an additional acidic variant form which likely accounted for altered cAMP-dependent protein kinase activity. Poly(A+) RNA was isolated from Y1 and Kin mutant cells and was translated in a cell-free, reticulocyte lysate system in the presence of L-[35S]methionine. The RI synthesized from poly(A+) RNA was immunoprecipitated from the translation mixture and analyzed on isoelectric focusing gels. The poly(A+) RNA from the Kin mutant clones directed the synthesis of parental and acidic variant forms of RI. These results suggest that the altered electrophoretic forms of RI arise from mutations in one of two RI genes rather than from post-translational modifications of the protein. The coexistence of parental and variant forms of RI in the Kin mutants indicate that the mutations are codominant.

Elderly adults' perception of their own cognitive development during the adult years

Individuals between the ages of sixty-five and seventy-five were asked a number of questions regarding which of their cognitive abilities they think have changed with age and, further, what factors they think are responsible for such age changes. Questions were asked in two areas of cognitive functioning--memory and problem solving. With respect to memory, the reports of the elderly adults corresponded well with the results of memory research, which indicates that most memory abilities tend to decrease with increasing age. The elderly adults suggested that activity level, amount of contact with the information to be remembered, practice remembering, the perceived importance of the information to be remembered, and expectations regarding changes in memory are all factors that may contribute to age changes in memory. With respect to problem solving, on the other hand, the reports of the elderly did not correspond with the research. Research indicates that such abilities probably decline with increasing age while the elderly reported that they think that their problem-solving abilities have actually increased with age. Factors that were mentioned as possible causes of the reported increases in problem-solving ability were experience, good health, and taking more time to solve a problem.

Uterine and kidney aspartate aminotransferase activity in ethinylestradiol- and norgestrel-treated rats

Aspartate aminotransferase (AST) activity was measured in the kidneys and uteri of mature female rats to determine what effect, if any, treatment with ethinylestradiol (EE), norgestrel (NOR) or a combination of both hormones might have on the relationship of pyridoxal-PO4 to AST activity. Treatment with EE had no effect on the degree of saturation of kidney AST with pyridoxal-PO4, AST activity/mg kidney or total kidney AST activity compared to controls. Kidney weight was, however, significantly elevated (P < 0.05). The same AST parameters were elevated (P < 0.05) in rats treated with NOR or EE + NOR. Saturation of AST by pyridoxal-PO4 was not altered by hormone treatment in uteri, but AST activity/mg uterus and total uterine activity were lowered by NOR or EE + NOR treatment. Exposure to EE alone elevated these last two parameters. It is noteworthy that the same hormone can both stimulate or inhibit AST, depending on the organ in question. Since progestin-dominant contraceptives are becoming more commonplace, it is important to observe that the progestin was more effective in altering AST parameters than was the estrogen.

Long-term evaluation of chlorambucil plus prednisone in the idiopathic nephrotic syndrome of childhood

We evaluated the long-term effects of a five to 15-week course of chlorambucil and prednisone in 59 children with idiopathic nephrotic syndrome who had previously received prednisone alone and had had frequent relapses or steroid dependency or resistance. By actuarial analysis of 65 courses of dual therapy followed up for one to 12 years (mean, 5.0), we found that 95 per cent of patients were in remission at one year and 85 per cent at four years. All but two had remissions lasting longer than those induced by steroids alone, and only eight others had one or more relapses after therapy. Life-table analysis of two dosage schedules of chlorambucil at four years showed that 91 per cent of patients on low doses and 80 per cent of those on high doses were still in remission. Although immediate complications were minimal, the potential for long-term toxicity still requires careful selection of patients who receive chlorambucil. Prolonged use of chlorambucil in daily doses above 0.3 mg per kilogram of body weight per day or cumulative doses above 14 mg per kilogram is no longer warranted. Measured in terms of both the immediate and long-term responses, chlorambucil appears to lower the frequency of relapses in idiopathic nephrotic syndrome.

Control of high density bacterial contamination of the fiberoptic bronchoscope

In a double-blind study the fiberoptic bronchoscope was contaminated with five pathogenic organisms, each at a concentration of 10(9) organisms per milliliter. The shaft and inner channel of the bronchoscope were cleansed with five antiseptic regimens. Each regimen included equal 120-ml aliquots of one, two, or three solutions, respectively. The five different regimens were as follows: (1) physiologic saline solution; (2) 70 percent solution of isopropyl alcohol, followed by physiologic saline solution; (3) alkaline glutaraldehyde, followed by 70 percent solution of isoproply alcohol, followed by physiologic saline solution; (4) benzalkonium chloride, followed by 70 percent isopropyl alcohol, followed by physiologic saline solution; and (5) povidone-iodine solution, followed by 70 percent solution of isopropyl alcohol, followed by physiologic saline solution. The four regimens involving solutions other than saline solution alone were effective in reducing the count of residual bacterial colonies to 10(4) colonies per milliliter or less.