Femtosecond Raman frequency shifter-pulse compressor.

The conversion to the first Stokes component at a wavelength of 1.8 µm of ytterbium laser radiation with a pulse duration of 270 fs by stimulated Raman scattering (SRS) in hydrogen was carried out by using double-pulse pumping scheme. Simultaneously with SRS the process of nonlinear phase modulation of laser and Stokes waves was observed. The spectrally broadened chirped Stokes pulse was compressed to 35 fs in fused silica optical elements at the output of a Raman cell.

Note: 15-fs, 15-µJ green pulses from two-stage temporal compressor of ytterbium laser pulses.

15-fs, 15-µJ light pulses at the central wavelength of 515 nm were generated by two-stage nonlinear compression of 300-fs, 150-µJ ytterbium laser pulses. The compression was based on the pulse spectrum broadening by self-phase modulation in gas filled capillary and second harmonic generation in crystal.

[New-onset pulmonary tuberculosis patients with schizophrenia: course and efficiency of treatment].

To investigate the specific features of the course and efficiency of treatment, the authors examined 72 patients with new-onset pulmonary tuberculosis and schizophrenia versus 68 new-onset pulmonary tuberculosis patients without mental diseases. Tuberculosis has been found to be identified in 66.7% of schizophrenics by lung fluorography made at a mental hospital or specialized dispensary. This mainly diagnoses the circumscribed forms of the disease with a low bacterial discharge, drug resistance, and cavitation while in nonschizophrenics, pulmonary tuberculosis is detected in 33.3% of cases in general health care network facilities. Following 9 months, complex treatment of pulmonary tuberculosis in schizophrenics succeeded in ceasing bacterial discharge, as shown by microscopy and sputum cultures, in 94.4 and 84.5% of cases, respectively. However, in schizophrenics receiving chemotherapy for tuberculosis, adverse reactions are revealed in 63.9% of cases, with this the incidence of these reactions depends not only on antituberculosis drugs, but also on drugs taken by patients for schizophrenia. Schizophrenic patients with pulmonary tuberculosis need an individual approach to treating the patient, longer treatment, intermittent use of antituberculosis agents, regular clinical and laboratory monitoring of the development of side effects, and complex pathogenetic treatment.

Raman frequency shifter for laser pulses shorter than 100 fs.

The technique of frequency shifting of sub-100 fs laser pulses was developed. It is based on the stimulated Raman scattering pair of chirped laser pulses with orthogonal polarization. The 50 fs laser pulse at the wavelength of 810 nm was converted to 68 fs Stokes pulse at the wavelength of 1060 nm with energy conversion efficiency of 20%.

Multifrequency parametric infrared Raman generation in KGd(WO(4))(2) crystal with biharmonic ultrashort-pulse pumping.

Mutlifrequency parametric Raman generation was carried out in a KGd(WO(4))(2) crystal by use of a dual-wavelength Ti:sapphire laser system. It was found that with femtosecond pump pulses the efficiency of Raman generation is low because of the onset of self-phase modulation. The mechanism for suppression of stimulated Raman scattering by self-phase modulation is discussed. Employing 2-ps-long chirped pulses generated four Stokes and one anti-Stokes component.

HIV infection of human fetal neural cells is mediated by gp120 binding to a cell membrane-associated molecule that is not CD4 nor galactocerebroside.

HIV infection of central nervous system (CNS) tissue is a common finding in both adult and pediatric AIDS. Because most children are believed to be infected perinatally, we have developed a model of HIV CNS infection that utilizes explant organotypic cultures of human fetal CNS tissue. Using this model we previously reported that both lymphocytotropic and monocytotropic HIV isolates infect microglia and astrocytes. However, the mechanism by which HIV infects these cells remains to be elucidated. We have observed that neural cell infection in these cultures may be the result of receptor-mediated endocytosis. In order to confirm this observation and to determine the ligand responsible for this process, organotypic cultures were exposed to untreated HIV, HIV pretreated with soluble CD4 (sCD4) or, as a control, heat-inactivated HIV. To address the question of a putative receptor for HIV infection, CNS cultures were either untreated or pretreated with gp120 or with the deglycosylated form of this protein. Other cultures were treated with antibodies to CD4 (anti-T4A) or to galactocerebroside (GC). Results demonstrate that pretreatment of either HIV with sCD4 or CNS cultures with gp120 significantly inhibits HIV infection. The inhibition of infection was demonstrated by a reduction in the number of cells positive for HIV proteins and by decreases in HIV proviral DNA and p24 production. Pretreatment of CNS cultures with deglycosylated gp120, anti-T4A or anti-GC antibodies did not inhibit HIV infection. These data suggest that HIV gp120 is needed for binding to a surface molecule on CNS cells that is not CD4 nor GC and that this molecule may function as a receptor and lead to infection of neural cells.

Neural cell targets of human immunodeficiency virus type 1 in human fetal organotypic cultures.

Some children infected by HIV-1 demonstrate nervous system disease. Because a significant percentage of these children are believed to be infected during gestation and it is thought that HIV-1 may infect distinct glial populations, this work tested the hypothesis that different HIV-1 isolates can infect cells of the developing human fetal central nervous system (CNS). Central nervous system organotypic tissue cultures derived from human fetal brain enable the study of complex interactions between CNS cell types. Central nervous system organotypic cultures were exposed to lymphocytotropic (L-tropic) or monocytotropic (M-tropic) HIV-1 isolates and monitored for viral infection. HIV-1 gp41 and p24 antigens were detected by immunocytochemistry (ICC), HIV-1 RNA was localized in the cytoplasm of CNS cells by in situ hybridization (ISH), and viral DNA was detected by polymerase chain reaction (PCR) in HIV-1-exposed cultures. Double-label ICC identified HIV-1 antigens in both microglia and astrocytes. These results demonstrate that both L- and M-tropic isolates infect microglia and astrocytes in human fetal organotypic cultures. In addition, HIV-1 infection was detected in culture supernatants up to day 57 postinfection and at 90 days by coculture with susceptible CEM cells. HIV-1 infection of neural cells appears to be productive. This model may permit further examination of the interaction of HIV-1 with the developing human CNS and the mechanisms of AIDS-associated neuropathology.

Ultrabroad-bandwidth multifrequency Raman generation.

We report on the modeling of transient stimulated rotational Raman scattering in H(2) gas. We predict a multifrequency output, spanning a bandwidth greater than the pump frequency, that may be generated without any significant delay with respect to the pump pulses. The roles of dispersion and transiency are quantified.