Determination of the refractive index of a bacteriorhodopsin film.

The wavelength-dependent refractive index of a bacteriorhodopsin thin film is measured by the use of a modified critical-angle technique. The effect of the host bovine skin gelatin on the refractive index is analyzed. The measured data on the thin film can be useful for system applications. The methods and procedures are generally applicable to any optically absorbing thin films.

Amino acid membrane transport properties of L1210 cells resistant to cisplatin.

A mouse L1210 leukemia cell line was made 18-fold resistant to the chemotherapeutic agent cisplatin. The drug resistant cells exhibited changes in morphologic and biochemical properties from the sensitive cells. Uptake of labeled cisplatin was only slightly decreased in the resistant cells. However, the exogenous methionine requirement for these cells was 18-fold less than for parent cells. This decrease in the methionine requirement was also associated with differences in both methionine metabolism and transport. Membrane transport analysis revealed different Kt and Vmax properties for methionine and a nonmetabolizable amino acid analogue between the two cell lines. In L1210 cells resistant to cisplatin, decreases in amino acid transport, plus changes in amino acid substrate specificities, may be related to a drug-membrane phenomenon which could be one mechanism of resistance to chemotherapeutic agents.

Inhibition of amino acid transport by cis-diamminedichloroplatinum(II) derivatives in L1210 murine leukemia cells.

The uptake of cis-diamminedichloroplatinum(II) (cisplatin) has been studied in the L1210 murine lymphoid leukemia cell line. Labeled cisplatin and its aquated derivatives were resolved by high-performance liquid chromatography on a strong cationic exchange column. After 10 min of incubation of cisplatin with the cells, the major portion of the non-protein-bound platinum was in the form of cisplatin. However, a portion of this platinum was converted with time to a derivative which coeluted with the monoaquo derivative of cisplatin. With the appearance of this derivative, there was a concomitant inhibition of sodium-dependent amino acid transport as measured by the uptake of aminoisobutyric acid and methionine. Furthermore, the exposure of L1210 cells to a preparation of predominantly aquated product(s) of cisplatin inhibited amino acid uptake following a brief (2-min) incubation, whereas measurable inhibition of amino acid uptake by cisplatin required a longer preincubation period. This inhibition of aminoisobutyric acid and methionine was dependent on the concentration of platinum. Aminoisobutyric acid and methionine were shown to be concentrated in L1210 cells in the presence of sodium ions, and competition experiments suggest similar uptake systems. Since L1210 cells are methionine-auxotrophic leukemic cells, inhibition of essential amino acid transport by cisplatin may be a mechanism of cytotoxic action.

Complement-fixing antiperipheral nerve myelin antibodies in patients with inflammatory polyneuritis and with polyneuropathy and paraproteinemia.

Serum from patients with peripheral neuropathies was tested for antiperipheral nerve myelin antibodies by complement fixation. Antibody activity was detected in 5 of 20 patients with acute or chronic remitting polyneuritis and in 4 of 20 patients with polyneuropathy and paraproteinemia but not in patients with other types of neuropathy, neurologic disease, or immunologic disease. In three patients with IgM paraproteinemia, the complement-fixing activity resided in the IgM fraction; in one patient with chronic inflammatory polyneuritis, antibody activity resided in the IgG fraction. In the inflammatory polyneuropathies, antibody titers did not always correlate with disease activity. Sera from patients with remitting polyneuropathies reacted with either human or rabbit peripheral nerve myelin, but sera from patients with paraproteinemia reacted only with human myelin.

Plasma cell dyscrasia and peripheral neuropathy: identification of the myelin antigens that react with human paraproteins.

In some cases of polyneuropathy and plasma cell dyscrasia, the monclonal antibodies react with human peripheral nerve myelin. To identify the myelin antigens involved, we separated the proteins of human central and peripheral nerve myelin by polyacrylamide gel electrophoresis, transferred the proteins onto nitrocellulose sheets, and used an immunoenzymatic technique to detect the reactive antigens. Serum IgM but not IgG from three patients with neuropathy and complement-fixing anti-human myelin IgM paraproteins immunostained a protein of approximately 100,000 daltons in human peripheral nerve myelin and a protein or closely migrating proteins of similar size in human central nervous system myelin. In a fourth patient, both IgM and IgG immunostained the antigen. Immunostaining was specific for the paraprotein light chain type, and absorption of the patients' sera with human peripheral nerve myelin eliminated the reaction with the central nervous system proteins. No reaction was seen with rabbit peripheral nerve myelin or with membranes prepared from human myotubes, human T cells, or human fibroblasts. Control sera from six patients with neuropathy and IgM paraproteins that did not react with myelin, from four patients with IgM paraproteins but no neuropathy, and from three normal subjects did not immunostain myelin.

A comparison of the Bem Sex-Role Inventory and the Heilbrun Masculinity and Femininity Scales.

This study compares two instruments which have recently been devised to measure sex-role identification, Heilbrun's Masculinity and Femininity Scales and the Bem Sex-Role Inventory. Correlations between the masculine and feminine scales of these instruments were significant for male but not female subjects; intrascale comparisons found no relationship between the Bem scales but moderate correlations between the Heilbrun scales for male subjects. There was agreement between the two measures in classifying approximately 47% of the subjects into one of the four sex-role categories. Misclassification occurred primarily on categories which have been found to show considerable overlap in personality characteristics.

A comparison of twins for degree of closeness and field dependency.

An examination of Witkin's construct of field dependency was undertaken with a sample of adolescent twin pairs to determine if the degree of closeness in twin relationships would be reflected in the twins' degree of field dependency. Sixteen pairs of monozygotic (MZ) adolescent male twins and the same number of dizygotic (DZ) same-sexed male twins were administered three measures: Nichols and Bilbro's (1966) zygosity questionnaire, Paluszny and Beit Hallahmi's (1974) semantic differential measure of closeness, and Jackson's (1956) short form of the Embedded Figures Test. No significant differences were found between the MZ and DZ twin groups with regard to their expressed closeness to one another, as measured with Paluszny and Beit-Hallahmi's index of closeness; in addition, there were no significant differences between the two twin groups on the measure of field dependency. However, significant relationships of these two variables with intelligence were found and possible reasons for such an occurrence were offered.

Sexual identity and personality variables in normal and disturbed adolescent girls.

Disturbed and normal adolescent girls from a working class background were compared on three measures of sex role as well as self and ideal personality characteristics. Both disturbed and normal girls had an appropriate sex-role identity on two of the measures. An association was found between normal status and high self scores on nurturance, affiliation, and endurance, and between pathological status and succorance. Although differences existed on some self reported traits between pathological and normal status, all groups tended to see the ideal female teenager as having an equitable balance among the personality variables and higher than they rated themselves on deference, nurturance, and affiliation and lower on autonomy. It was concluded that the presence or absence of certain adaptive personality traits may be more important than sex role disturbance in pathology.