Extremely Nonperturbative Nonlinearities in GaAs Driven by Atomically Strong Terahertz Fields in Gold Metamaterials.

Terahertz near fields of gold metamaterials resonant at a frequency of 0.88 THz allow us to enter an extreme limit of nonperturbative ultrafast terahertz electronics: Fields reaching a ponderomotive energy in the keV range are exploited to drive nondestructive, quasistatic interband tunneling and impact ionization in undoped bulk GaAs, injecting electron-hole plasmas with densities in excess of 10^{19} cm^{-3}. This process causes bright luminescence at energies up to 0.5 eV above the band gap and induces a complete switch-off of the metamaterial resonance accompanied by self-amplitude-modulation of transmitted few-cycle terahertz transients. Our results pave the way towards highly nonlinear terahertz optics and optoelectronic nanocircuitry with subpicosecond switching times.

Characterization of bovine coronavirus isolates/from eight different states in the USA.

Bovine coronavirus isolates from eight different states of the USA were compared for their antigenic properties and susceptibility to hygromycin B. Antigenic differences were observed among the isolates in a one-way hemagglutination-inhibition (HI) test using a polyclonal antiserum against the Mebus bovine coronavirus isolate. Differences were observed on isoelectric focusing among viral proteins with isoelectric points between 4.45-4.65. Most of the BCV isolates were susceptible to hygromycin B (0.5 mM) whereas a few hygromycin B resistant isolates were also found.

Colposcopic biopsies versus loop electrosurgical excision procedure cone histology in human immunodeficiency virus-positive women.

OBJECTIVE: To compare the discrepancy between colposcopically directed punch biopsy and excisional cone biopsy in human immunodeficiency-positive (HIV+) vs. HIV-negative (HIV-) women. STUDY DESIGN: We performed a case-control analysis of women treated with excisional cone biopsy after an abnormal colposcopic punch biopsy. Punch and cone biopsy histology were compared in 29 HIV+ (mean CD4 = 251 cells/mm3, 10 with the acquired immunodeficiency syndrome) and 31 HIV- women. Only patients with no prior treatment for cervical dysplasia, satisfactory colposcopy and cervical cytologic smears concordant with colposcopic biopsies were included. RESULTS: Disagreement between punch biopsy and cone histology was evident in 41% (12/29) of HIV+ patients and 48% (15/31) of seronegative women (chi 2, P = .78). The cone specimen had a higher grade lesion than the punch biopsy in 38% (11/29) of HIV+ patients and 32% (10/31) of seronegative women (P = .65). Overall, patients with HPV, cervical intraepithelial neoplasia (CIN) I or II on punch biopsy had CIN III on 30% of cone biopsies (5/23 HIV+ vs. 9/23 HIV-women, P = .2). In HIV+ women with HPV or CIN I on punch biopsy, 50% (9/18, 95% confidence interval 26-74%) had CIN II or III on the excisional cone vs. 18% (2/11) HIV-patients (Fisher's test, P = .13). However, in HIV+ patients with CIN II or III on cone biopsy, 47% (9/19) had only CIN I or human papillomavirus on punch biopsy as compared to 9% (2/22) HIV-patients (chi 2, P = .01). CONCLUSION: Colposcopically directed punch biopsies are poor predictors of cone histology in both HIV+ and HIV-patients. Based on confidence intervals, at least 26% and as many as 74% of HIV+ women with CIN I on punch biopsy may have a significantly worse lesion on cone biopsy despite satisfactory colposcopy. Though CIN I may be observed in immunocompetent women, due to the likelihood of a more advanced lesion, observation may not be justified in HIV+ women.

The value of cervical cytology in HIV-infected women.

The purpose of this study was to assess the ability of cytology to predict the results of colposcopically directed cervical biopsies in HIV-infected women. We performed a case-control study of 52 HIV(+), 31% of whom had AIDS, and 57 HIV(-) women referred to two tertiary care centers for colposcopy from July 1991 to November 1993. All 57 HIV(-) controls and 27 HIV (+) cases underwent colposcopy for evaluation of an abnormal Pap smear. The remaining HIV(+) cases (n = 25) had colposcopy as part of their routine assessment. In women with abnormal Pap smears, colposcopic biopsy agreed with the Pap smear results in 83% of 24 HIV(+) women and 65% of 37 controls (chi 2; P = 0.34). For patients with low-grade SIL on Pap smear, 14% of HIV(+) and 11% of HIV(-) women had moderate or severe dysplasia on biopsy (P = 0.52). The positive predictive value of an abnormal Pap smear was 96% in HIV(+) women vs 78% in noninfected patients (P = 0.05). In the overall series of 52 HIV(+) women, the Pap smear did not match the biopsy in 44% of patients and was less severe than the cervical biopsy results in 91% of these mismatches. The Pap smear had a sensitivity of 57%, a specificity of 92%, a positive predictive value of 96%, and a negative predictive value of 39%, when compared to biopsy results in HIV-seropositive patients. Pap smears missed 43% of biopsy-proven intraepithelial lesions in this series of HIV (+) women. However, when abnormal, the Pap smear was no worse in predicting the presence and degree of an intraepithelial lesion in HIV(+) women than in noninfected women. These characteristics may justify immediate treatment of HIV(+) women at the time of colposcopy after an abnormal Pap smear given its high positive predictive value.

Anti-brain antibodies in the sera of rheumatoid arthritis patients: relation to disease activity and psychological status.

Auto-antibodies reactive with brain are known to occur in various immunological disorders. Their significance with respect to disease activity, neurological manifestations, or psychological status is, however, not known. In previous studies it was found that there were antibodies reactive with brain in the sera of patients with rheumatoid arthritis (RA). The present study sought to confirm and extend our previous findings and determine the significance of these antibodies with respect to disease activity. It also investigated a possible connection between psychological function in RA and these auto-antibodies. Sera drawn from 14 RA patients, at bi-weekly intervals over 3 months, showed the presence of antibodies against transmembrane proteins from murine brain. These antibodies correlated positively with rheumatoid factor and joint swelling. There was a trend toward a correlation between depression and daily mood scores and the number of antibodies reactive with brain. In addition, a correlation between cognitive coping styles in RA patients and auto-antibodies was found. There was also evidence for a sub-population of pathogenic antibodies.

Influence of some physical factors on survival of Marek's disease vaccine virus.

Cell-associated Marek's disease (MD) vaccine was suspended at dilutions normally used for vaccination in seven commercially available diluents and in tryptose phosphate broth. The stability of diluted vaccines was determined by assay in cell cultures subjected to 0 to 37 C for 0 to 90 minutes. Optimum holding temperatures for MD vaccine virus survival varied with the specific diluents employed. Some diluents afforded greatest survival when dilution was at 0 C and held at 0 C, while others performed best when dilution was at 25 C followed by cooling and holding at 0 C. Diluents which allowed greatest survival when tested at 37 C also performed well under other temperature regimes. Spectinomycin dihydrochloride pentahydrate and various buffering compounds were added to commercial diluents used for diluting MD vaccine. Additives producing osmolality of 745 mOsm/kg and higher markedly reduced vaccine virus survival. The adverse effects of high osmotic pressure were accentuated by extended holding time, elevated incubation temperature, and physical manipulations including mechanical mixing or expressing through a syringe and needle. Satisfactory MD vaccine virus survival was afforded by a commercial diluent especially formulated to accommodate the pH osmolality changes produced by adding spectinomycin dihydrochloride pentahydrate.