Possibility of diagnosing meningitis by gas chromatography: cryptococcal meningitis

Serine/arginine-rich splicing factors: the bridge linking alternative splicing and cancer

The serine/arginine-rich splicing factors (SRs) belong to the serine arginine-rich protein family, which plays an extremely important role in the splicing process of precursor RNA. The SRs recognize the splicing elements on precursor RNA, then recruit and assemble spliceosome to promote or inhibit the occurrence of splicing events. In tumors, aberrant expression of SRs causes abnormal splicing of RNA, contributing to proliferation, migration and apoptosis resistance of tumor cells. Here, we reviewed the vital role of SRs in various tumors and discussed the promise of analyzing mRNA alternative splicing events in tumor. Further, we highlight the challenges and discussed the perspectives for the identification of new potential targets for cancer therapy via SRs family members.

Applications of cellular fatty acid analysis

More than ever, new technology is having an impact on the tools of clinical microbiologists. The analysis of cellular fatty acids by gas-liquid chromatography (GLC) has become markedly more practical with the advent of the fused-silica capillary column, computer-controlled chromatography and data analysis, simplified sample preparation, and a commercially available GLC system dedicated to microbiological applications. Experience with applications in diagnostic microbiology ranges from substantial success in work with mycobacteria, legionellae, and nonfermentative gram-negative bacilli to minimal involvement with fungi and other nonbacterial agents. GLC is a good alternative to other means for the identification of mycobacteria or legionellae because it is rapid, specific, and independent of other specialized testing, e.g., DNA hybridization. Nonfermenters show features in their cellular fatty acid content that are useful in identifying species and, in some cases, subspecies. Less frequently encountered nonfermenters, including those belonging to unclassified groups, can ideally be characterized by GLC. Information is just beginning to materialize on the usefulness of cellular fatty acids for the identification of gram-positive bacteria and anaerobes, despite the traditional role of GLC in detecting metabolic products as an aid to identification of anaerobes. When species identification of coagulase-negative staphylococci is called for, GLC may offer an alternative to biochemical testing. Methods for direct analysis of clinical material have been developed, but in practical and economic terms they are not yet ready for use in the clinical laboratory. Direct analysis holds promise for detecting markers of infection due to an uncultivable agent or in clinical specimens that presently require cultures and prolonged incubation to yield an etiologic agent.

Rapid diagnostic methods for aspergillosis

Conventional laboratory methods are always unsatisfactory for the antemortem diagnosis of systemic mycoses, especially aspergillosis, in immunocompromised patients and those with acquired immune deficiency syndrome (AIDS), regardless of their age. There is increasing proof that aspergillosis is not limited to pulmonary, sinus or nasal regions. These facts, plus the high mortality rate, indicate a tremendous need for reliable and rapid methods of diagnosing this infection. Accordingly, refined techniques such as solid-phase radioimmunoassay (SPIRA), crossed-immunoelectrophoresis (CIE), crossed-radioimmunoelectrophoresis (CRIE), radioallergosorbent test (RAST), radioimmunoprecipitation assay (RIPA), paper radioimmunosorbent test (PRIST), computerized enzyme-linked immunosorbent assay (ELISA), biotin avidin enzyme-linked immunosorbent assay and gas-liquid chromatography (GLC) are being considered or used in clinical laboratories for diagnosing aspergillosis. The advantages and limitations of the RIA, ELISA and GLC methods are briefly discussed.

Gas chromatography in the identification of microorganisms and diagnosis of infectious diseases

Gas-liquid chromatography (GLC) continues to find increasing applications in the characterization of microorganisms and the diseases associated with them. GLC has been used to characterize microorganisms through qualitative and quantitative analyses of cellular structural components and soluble extracts and metabolic by-products. Chromatographic patterns, or fingerprints, can be used to differentiate between very closely related microorganisms, even strain differences, and provides a potentially powerful tool for future taxonomic studies and more precision in definitive microbial classification. However, the most valuable use of GLC is in the identification of disease through patterns obtained by direct analysis of body fluids. Chromatographic fingerprints of microbial metabolites and compounds associated with the host response to infection and even noninfectious disease can be used to develop relatively simple GLC diagnostic methods. These methods are specific, sensitive, and rapid. This review examines the use of GLC for identification of infectious diseases through the analysis of body fluids, spent culture media, and cellular materials and suggest other clinical areas where its diagnostic potential has yet to be developed.

Anaerobic bacteria in nonspecific vaginitis

To study the cause of nonspecific vaginitis, we analyzed vaginal fluid from normal women and from 53 women with nonspecific vaginitis, using quantitative anaerobic cultures and gas-liquid chromatography for short-chained organic-acid metabolites of the microbial flora. In normal vaginal fluid, lactate was the predominant acid, and the predominant organisms were lactobacillus and streptococcus species (lactate producers). In nonspecific vaginitis, lactate was decreased, whereas succinate, acetate, butyrate, and propionate were increased, the predominant flora included Gardnerella (Haemophilus) vaginalis (acetate producer), and anaerobes, which included bacteroides species (succinate producers) and peptococcus species (butyrate and acetate producers). After metronidazole therapy, symptoms and signs of nonspecific vaginitis cleared, butyrate and propionate disappeared, and lactate and lactate-producing organisms became predominant. We conclude that certain anaerobes act with G. vaginalis as causes of nonspecific vaginitis, and that a high ratio of succinate to lactate in vaginal fluid is a useful indicator in the diagnosis of this condition.

Frequency-pulsed electron capture gas-liquid chromatography and the tryptophan color test for rapid diagnosis of tuberculous and other forms of lymphocytic meningitis

A total of 260 samples of cerebrospinal fluid received from Egypt, the United States, Canada, and South America were examined by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC) for tuberculous and other forms of lymphocytic meningitis. Thirty-four of the specimens were culture positive for M. tuberculosis, and four cerebrospinal fluid specimens of herpes meningitis were established by immunological techniques. The compound, 3-(2'-ketohexyl)-indoline, was found in about 60% of the Egyptian tuberculous specimens and none of the culture-positive American specimens. the carboxylic and hydroxy acid FPEC-GLC profiles were used effectively in conjunction with other clinical data to make the diagnosis even in the absence of 3-(2'-ketohexyl)indoline. Herpes meningitis and mixed infections of Myeobacterium tuberculosis-herpes, M. tuberculosis-leptospira, and M. tuberculosis-Haemophilus influenzae produced profiles different from each other and from pure culture cases. The color test for tuberculous meningitis was evaluated, and free tryptophan was eliminated as the source of color reaction. Indications are that 3-(2'-ketohexyl)indoline, in most cases, is not responsible for the positive color reaction. Differences in the clinical and FPEC-GLC data obtained from samples from different geographical regions are discussed.

Detection of 3-hydroxy fatty acids at picogram levels in biologic specimens. A chemical method for the detection of Neisseria gonorrhoeae?

A method for the detection of 3-hydroxy dodecanoic acid at low picogram levels is described. The procedure involves preparation of a heptafluorobutryl derivative of the butyl ester of the fatty acid and its detection by gas-liquid chromatography using an electron capture detector. The method was adapted for use with biological specimens. Potential of the method for screening for gonococcal infection is discussed. Limitations of the method are that about 105 Neisseria gonorrhoeae cells are required for detection and that interfering substances are a major problem working at maximum sensitivity of the electron capture detector necessitating complex purification procedures. The method eliminates the need to maintain the viability of cells in specimens, thus facilitating collection and transport of specimens.

Possible use of frequency-pulse-modulated electron capture gas-liquid chromatography to identify septic and aseptic causes of pleural effusions

Frequency-pulse-modulated electron capture gas-liquid chromatography was used in conjunction with appropriate derivatization procedures to obtain chromatograms from extracts of pleural effusions. These chromatograms were used to rapidly classify the various types of pleural effusions. With this method we have been able to distinguish among a limited number of effusions caused by congestive heart failure, Mycobacterium tuberculosis, and some other types of bacterial empyemas and pleural effusions.

Development of specific tests for rapid detection of Escherichia coli and all species of Proteus in urine

Proteus mirabilis was distinguishable from Escherichia coli and from several other species that may be associated with urinary tract infections when grown in a nutrient medium supplemented with 0.1 M L-methionine by the formation of large amounts of dimethyl disulfide and methyl mercaptan, which were detected by head-space gas-liquid chromatography (HS-GLC). E. coli could be detected by the same HS-GLC technique by ethanol production from methionine peptone water enriched with 1% either lactose or arabinose but not by any product from 10 amino acids tested. Ethanol from lactose was detected early in the exponential phase of growth. Significant numbers, 10(5) or more per ml, of E. coli in urine could be detected in about 5 h by ethanol production from an unshaken culture of urine in lactose methionine peptone water buffered at pH 7.2 (urine test medium); only a trace of dimethyl disulfide was produced. Significant numbers of P. mirabilis in urine could be detected in 4 h by dimethyl disulfide production and in 5 h by methyl mercaptan production from a shaken culture of urine in urine test medium; no ethanol was produced. Incubation of urine specimens in the test medium followed by examination by HS-GLC is proposed as a rapid method of detecting whether or not the urine contains significant numbers of E. coli or a species of Proteus.

Rapid diagnosis of lymphocytic meningitis by frequency-pulsed electron capture gas-liquid chromatography: differentiation of tuberculous, cryptococcal, and viral meningitis

Cerebrospinal fluid specimens from patients with tuberculous (17 cases), cryptococcal (15 cases), and viral (14 cases) meningitis were analyzed by frequency-pulsed electron capture gas-liquid chromatography and mass spectrometry. Compounds that disappeared after therapy were found to be present in each of these specimens and were not detected in controls. They occurred in repetitive patterns such that these three types of meningitis could be rapidly distinguished. The compound associated with tuberculous meningitis has been tentatively identified. These finding have implications for rapid diagnosis, pathophysiological studies, and possible new therapeutic approaches.

Picorna- and togavirus infection of cells detected by gas chromatography

Viral infection of cells causes chemical and metabolic changes, which can be detected by gas chromatography (GC) of ether extracts of supernatant fluids and cell homogenates before any significant damage to the cells is observable microscopically. The characteristic and specific GC patterns obtained from BHK-21 and Vero cell cultures infected with encephalomyocarditis, polio, echoviruses, and a togavirus make it possible to distinguish between these infecting viruses. The appearance of 1 or 2 compounds, represented by GC peaks with TR values of 302 and 677 seconds seems to be specific for these viruses. Other peaks found in the supernatant media 1-2 hours after infection probably represent cell constituents leaking into the medium as a result of damage to the cell membrane by the invading virus.