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Facebook is one of the most popular social networking sites. However, Facebook intrusion or addiction is a growing concern as it involves an excessive attachment to Facebook, which disrupts daily functioning. To date, few studies have examined whether cross-cultural differences in the measurement of Facebook addiction exist. The aim of this study was to investigate the cross-cultural validity and measurement invariance of the Facebook Intrusion Questionnaire (FIQ), one of the most widely used measures of Facebook addiction, across 25 countries (N = 12,204, 62.3% female; mean age = 25 years). Multigroup confirmatory factor analyses (MGCFA) assessed cross-cultural validity as well as invariance. Additionally, individual confirmatory factor analyses evaluated the factorial structure and measurement invariance across genders in each country. The FIQ demonstrated partial metric invariance across countries and metric (13 countries), scalar (11 countries) or residual (10 countries) invariance across genders within individual countries. A one-factor model indicated a good fit in 18 countries. Cronbach's alpha for the entire sample was .85. Our findings suggest that the FIQ may provide an adequate assessment of Facebook addiction that is psychometrically equivalent across cultures. Moreover, the questionnaire seems to be universal and suitable for studying different social media in distinct cultural environments. Consequently, this robust tool can be used to explore behaviours related to specific media that are particularly popular in any given country., (© 2024 International Union of Psychological Science.)

To improve the utility of mammary ductoscopy, we investigated the correlation between endoscopic findings and histologic findings using intraductal biopsy specimens. Seventy-one intraductal biopsy specimens obtained from 63 patients between October 2001 and March 2004 were analyzed retrospectively. All specimens were obtained from monotonous intraductal lesions immediately after observation by mammary ductoscopy and were composed of a pure histologic subtype. With regard to endoscopic findings, color was classified as yellow, red, white, or colorless, and morphology was classified as spherical, lobular, mulberry, or amorphous. The histologic subtype was classified as papillotubular, papillary, degenerated, papillary cancer, solid-type ductal carcinoma in situ (DCIS), or cribriform cancer. The relationship between histologic diagnosis, color, and morphology was investigated. Intraductal biopsy specimens included 25 specimens of carcinoma and 46 specimens of papilloma. There was no significant correlation between color and diagnosis. Fourteen of 25 carcinoma specimens were amorphous, and amorphous morphology was significantly suggestive of malignancy (p < 0.001). Further, cribriform cancer was associated with amorphous morphology and yellow color. Morphology may be a useful endoscopically delineated parameter for differentiating intraductal lesions.

A rapid, selective and sensitive method for the determination of pamidronate in human plasma and urine samples by gas chromatography (GC) has been developed. After deproteinization of the sample with trichloroacetic acid, pamidronate was converted into its N-isobutoxycarbonyl methyl ester derivative and measured by GC with flame photometric detection (FPD), using a HP-1 capillary column. The derivative preparation and GC analysis were accomplished within 30 min. The derivative was sufficiently volatile and stable, giving a single and symmetrical peak, and provided an excellent FPD response. The detection limit of pamidronate, at a signal-to-noise ratio of 3, was ca. 100 pg injected, and the calibration curve for this compound in the range 20-1000 ng was linear and sufficiently reproducible for quantitative determination. This method could be successfully applied to plasma and urine samples without a preliminary clean-up except for deproteinization with trichloroacetic acid, and pamidronate could be measured without any influence from coexisting substances. Overall recoveries of pamidronate added to plasma and urine samples were 93-97%. The coefficients of variation for intra-assay and inter-assay of pamidronate in these samples were 1.0-7.9% (n = 3) and 4.1-8.3% (n = 6), respectively.

A simple and rapid method for the determination of the 22 protein amino acids by capillary gas chromatography is described. The amino acids were converted into their N(O,S)-isobutoxycarbonyl (isoBOC) methyl ester derivatives and measured by GC with flame ionization detection using a DB-17 capillary column. Arginine was converted into ornithine by arginase treatment prior to the isoBOC reaction. The N(O,S)-isobutoxycarbonylation of amino acids with isobutyl chloroformate was completed within 15 s by sonication in aqueous alkaline media. All of the derivatives were quantitatively resolved as single symmetrical peaks within 9 min by GC on a single column. The detection limits of amino acids were 0.2-4.0 ng per injection, and the calibration curves were linear in the range 0.2-50 micrograms for each amino acid. This method was successfully applied to protein hydrolysate samples. The analytical results of amino acid compositions of several proteins are presented.

A selective and sensitive method for the determination of glutathione (GSH) and related aminothiols such as cysteine (Cys), cysteinylglycine (CysGly) and gamma-glutamylcysteine (gamma-GluCys) by gas chromatography (GC) has been developed. GSH and related aminothiols were converted into their N,S-isopropoxycarbonyl methyl ester derivatives and measured by GC with flame photometric detection using a short capillary column (5 m x 0.53 mm i.d.) of cross-linked DB-1. The calibration curves were linear in the range 1-25 nmol for GSH and in the range 0.2-5 nmol for other aminothiols, and the detection limits of GSH, Cys, CysGly and gamma-GluCys were approximately 5, 0.2, 0.3 and 0.5 pmol per injection respectively. This method was successfully applied to blood samples without prior clean-up, and GSH and related aminothiols in these samples could be analysed without any influence from coexisting substances. Overall recoveries of GSH and other aminothiols added to blood samples were 88-107%. The analytical results of free and total blood GSH and related aminothiols in normal subjects are presented.

A selective and sensitive method has been developed for the determination of sulphur amino acids by gas chromatography (GC). Sulphur amino acids were converted into their N(S)-isopropoxycarbonyl methyl ester derivatives and measured by GC with flame photometric detection using a DB-17 capillary column. The derivatives were sufficiently volatile and stable to give single symmetrical peaks. The detection limits of sulphur amino acids were ca. 0.5-1 pmol per injection, and the calibration curves were linear in the range 0.5-10 nmol for each sulphur amino acid. This method was successfully applied to small urine samples without prior clean-up, and sulphur amino acids in these samples could be analysed without any influence from coexisting substances. Overall recoveries of sulphur amino acids added to urine samples were 85-113%. The analytical results of free sulphur amino acid contents in urine samples of normal subjects are presented.

A selective and sensitive method for the determination of free and total proline (Pro) and 4-hydroxyproline (Hyp) by gas chromatography (GC) was developed. For free Pro and Hyp analysis, plasma and tissue homogenate were extracted with methanol. For total Pro and Hyp analysis, these samples were hydrolysed in 6 M HCl. After removal of primary amino compounds by the reaction with o-phthaldialdehyde, Pro and Hyp in methanol extract and acid hydrolysate were converted into their N-dimethylthiophosphoryl methyl ester derivatives and then determined by GC with flame photometric detection using a DB-5 capillary column. This method was successfully applied to small samples without prior clean-up, and Pro and Hyp in these samples could be analysed without any influence from coexisting substances. Overall recoveries of Pro and Hyp added to plasma and tissue samples were 92-106%. The analytical results of free and total Pro and Hyp in human plasma and mouse tissue samples are presented.

A selective and sensitive method has been developed for the analysis of free and bound forms of O-phosphoamino acids, such as O-phosphoserine, O-phosphothreonine and O-phosphotyrosine, in urine samples by gas chromatography (GC). For free O-phosphoamino acid analysis, the urine sample was extracted with trichloroacetic acid and run through an ion exchange column. For total (free plus bound) O-phosphoamino acid analysis, the urine sample was hydrolysed in acid and base in order to release the O-phosphoamino acid from peptides or proteins. O-Phosphoamino acids in these prepared samples were converted into their N-isobutoxycarbonyl trimethyl ester derivatives and then measured by GC with flame photometric detection (FPD-GC). The calibration curve was linear in the range of 10-500 ng for each O-phosphoamino acid, and the detection limits were 30-80 pg as injection amounts. O-Phosphoamino acids in the urine samples could be selectively determined by the FPD-GC method without any influence from coexisting substances. The recoveries of O-phosphoamino acids added to urines and urine hydrolysates were 90-98% and relative standard deviations were 1.5-8.0%. By using this method, we investigated an age dependence of O-phosphoamino acid excretion in normal subjects.

A selective and sensitive method has been developed for the determination of secondary amines by gas chromatography (GC). After removal of primary amines by the reaction with o-phthaldialdehyde, secondary amines were converted into their N-diethylthiophosphoryl derivatives and then measured by GC with flame photometric detection using a DB-1701 capillary column. The derivatives were sufficiently volatile and stable to give single symmetrical peaks. The detection limits of secondary amines were ca. 0.05-0.2 pmol per injection. N-Methylcyclohexylamine was used as an internal standard. The calibration curves for secondary amines in the range 1-20 nmol were linear and sufficiently reproducible for quantitative determination. This method was successfully applied to small urine samples without prior clean-up. Overall recoveries of secondary amines added to urine samples were 91-105%. By using this method, secondary amines in urine samples could be analysed without any influence from primary amines and other coexisting substances. The analytical results of secondary amine content in urine samples of normal subjects are presented.

A selective and sensitive method for the determination of low molecular weight aliphatic primary amines in urine is described. These amines were converted into their benzenesulphonyl derivatives by a modified Hinsberg procedure, and measured by gas chromatography with flame photometric detection (FPD-GC) using a DB-1 capillary column. The derivatives were very stable and provided excellent FPD responses. By FPD-GC, linear calibration curves were obtained in the range 10-200 ng of methylamine, ethylamine, n-propylamine, isobutylamine and n-butylamine using tert-butylamine as an internal standard, and the detection limits of these amines were ca. 6-25 pg as the injection amount. Benzenesulphonamide derived from ammonia was converted into its N-dimethylaminomethylene derivative which has a longer retention time, and separated from benzenesulphonyl derivatives of low molecular weight primary amines on the chromatogram. The recoveries of aliphatic primary amines added to urine samples were 91-107% and the relative standard deviations were 0.2-4.5%. Analytical results of aliphatic primary amine contents in urine samples of normal subjects are presented.