Stable, narrow-linewidth laser system with a broad frequency tunability and a fast switching time.

For a Rydberg atom-based sensor to change its sensing frequency, the wavelength of the Rydberg state excitation laser must be altered. The wavelength shifts required can be on the order of 10 nm. A fast-tunable narrow-linewidth laser with broadband tuning capability is required. Here, we present a demonstration of a laser system that can rapidly switch a coupling laser as much as 8 nm in less than 50 µs. The laser system comprises a frequency-stabilized continuous wave laser and an electro-optic frequency comb. A filter enables selection of individual comb lines. A high-speed electro-optic modulator is used to tune the selected comb line to a specific frequency, i.e., an atomic transition. Through Rydberg atom-based sensing experiments, we demonstrate frequency hopping between two Rydberg states and a fast switching time of 400 µs, which we show can be reduced to ∼50 µs with a ping-pong scheme. If updating the RF frequency is not required during frequency hopping, a 200 ns switching time can be achieved. These results showcase the potential of the laser system for advanced Rydberg atom-based radio frequency sensing applications, like communications and radar.

Quorum sensing activity in Ophiostoma ulmi: effects of fusel oils and branched chain amino acids on yeast-mycelial dimorphism.

AIMS: For Ophiostoma (Ceratocystis) ulmi, the ability to undergo morphological change is a crucial factor for its virulence. To gain an understanding of quorum-sensing activity in O. ulmi as it relates to yeast-mycelium dimorphism control, this study examines the effects of branched-chain amino acids as well as their fusel alcohols and fusel acids as quorum sensing molecules. METHODS AND RESULTS: In a defined medium containing glucose, proline and salts, O. ulmi grew as yeasts when the culture was inoculated with a high density of spores (2 × 10(7) CFU ml(-1) ) and as mycelia when inoculated with a low spore density (4 × 10(5) CFU ml(-1) ). The cultures displaying yeast morphology secreted a quorum-sensing factor that shifted the morphology from mycelia to yeast. This quorum-sensing molecule was lipophilic and extractable by organic solvents from the spent medium. Using GC/MS analysis, it was determined that the major compound in the extract was 2-methyl-1-butanol. A similar effect was observed when the branched-chain amino acids (fusel alcohol precursors) were used as the nitrogen source. E, E-farnesol had no effect on the morphology of O. ulmi. CONCLUSIONS: Addition of the branched-chain amino acids or one of the compounds detected in the spent medium, 2-methyl-1-butanol or 4-hydroxyphenylacetic acid, or methylvaleric acid, decreased germ tube formation by more than 50%, thus demonstrating a quorum sensing molecule behaviour in O. ulmi cultures. SIGNIFICANCE AND IMPACT OF THE STUDY: This study presents advances in the investigation of dimorphism in O. ulmi, complementing the existing scientific basis, for studying, understanding and controlling this phenomenon.

Early human IgH gene assembly in Epstein-Barr virus-transformed fetal B cell lines. Preferential utilization of the most JH-proximal D segment (DQ52) and two unusual VH-related rearrangements.

We have analyzed the phenotypic characteristics and IgH gene rearrangements in a panel of EBV-transformed B lineage cell lines from human fetal liver and bone marrow. Some lines contained only populations of immature, Ig- Be cells, while others contained mixed populations of mature and immature B cells. The majority of identifiable IgH rearrangements involved joining of the most JH-proximal D segment, DQ52, to various JH segments, implying that DQ52 is a preferred target for initial DJH rearrangements. Three other rearrangements involving VH-related sequences were also characterized. Two involved VHDJH joining using VH3 genes, although one of these had a very unusual DJH structure. The third consisted of inverted 3' signal sequences and flanking regions of a VH4 gene appended to a JH. The mechanisms by which the later rearrangement could have occurred and its potential physiological significance are discussed.

A human monoclonal macroglobulin with specificity for alpha(2----8)-linked poly-N-acetyl neuraminic acid, the capsular polysaccharide of group B meningococci and Escherichia coli K1, which crossreacts with polynucleotides and with denatured DNA.

We have described an IgM antibody from a patient with macroglobulinemia specifically reacting with poly-alpha(2----8)N-acetyl neuraminic acid (NeuNAc) the capsular polysaccharide of two important human pathogens, group B meningococcus and E. coli K1. This antibody has a narrowly defined specificity in its interactions with polysaccharides, being unable to bind poly-alpha(2----9)NeuNAc or alternating poly-alpha(2----8)alpha(2----9)NeuNAc. However, it shows interesting crossreactivity with seemingly unrelated polynucleotides and denatured DNA, supporting the hypothesis that charged groups with a given spacing may determine the specificity of antigen-antibody interactions on otherwise dissimilar molecular structures. Despite the crossreactivity with denatured DNA and polynucleotides, the antibody does not appear to have adverse effects in the patient. The antibody protects newborn rats against E. coli K1 infection, as well as the standard horse antiserum H46, and one would expect it to prove useful in humans as an adjunct to antibiotic therapy in infections with group B meningococcus and E. coli K1. We have attempted to clone the antibody-producing cells from peripheral blood, and have shown that the relevant cells are present and can be cultured.

Bioassay of solubilized Bacillus thuringiensis var. israelensis crystals by attachment to latex beads.

Solubilized crystals of Bacillus thuringiensis var. israelensis were 7000 times less toxic to Aedes aegypti larvae than intact crystals, presumably because mosquito larvae are filter feeders and selectively concentrate particles while excluding water and soluble molecules. A procedure is described whereby soluble toxins are adsorbed to 0.8-micrometer latex beads, with retention of toxicity. The latex bead assay should make it possible to analyze the structure and mode of action of the mosquito toxin.

Salmonella Typhi Colonization Provokes Extensive Transcriptional Changes Aimed at Evading Host Mucosal Immune Defense During Early Infection of Human Intestinal Tissue.

Commensal microorganisms influence a variety of host functions in the gut, including immune response, glucose homeostasis, metabolic pathways and oxidative stress, among others. This study describes how Salmonella Typhi, the pathogen responsible for typhoid fever, uses similar strategies to escape immune defense responses and survive within its human host. To elucidate the early mechanisms of typhoid fever, we performed studies using healthy human intestinal tissue samples and "mini-guts," organoids grown from intestinal tissue taken from biopsy specimens. We analyzed gene expression changes in human intestinal specimens and bacterial cells both separately and after colonization. Our results showed mechanistic strategies that S. Typhi uses to rearrange the cellular machinery of the host cytoskeleton to successfully invade the intestinal epithelium, promote polarized cytokine release and evade immune system activation by downregulating genes involved in antigen sampling and presentation during infection. This work adds novel information regarding S. Typhi infection pathogenesis in humans, by replicating work shown in traditional cell models, and providing new data that can be applied to future vaccine development strategies.

Results of conservative management of cervical intraepithelial neoplasia.

Cryotherapy and laser surgery have been the most frequently used conservative methods to treat cervical intraepithelial neoplasia (CIN) in the past decade. This report documents our experience using these modalities to treat 2773 patients between the years 1984-1989. One thousand eight hundred eleven women received laser surgery and the remaining 962 were treated with cryotherapy. In the first 2 years of the study period, only 78 patients were treated with laser surgery. Conversely, only 69 of the 979 patients treated in 1988 and 1989 had cryotherapy. As greater experience was gained with laser surgery, the success rates rose from 58.3% in 1984 to 95.5% in 1988. The success rate was similar for all grades of CIN. Overall, 11.2% of all patients were lost to follow-up. Among patients treated with laser surgery, 4.8% had postoperative bleeding that required either packing or, in two instances, sutures for hemostasis. Success with these methods appeared to be related to the size of lesion and not to the degree of histologic abnormality. The shift toward increasing use of laser surgery in our clinic was due to its precision in destroying identified lesions in the transformation zone. Our results indicate that both cryotherapy and laser surgery are simple, effective methods for the treatment of CIN.

Cryotherapy in the treatment of cervical intraepithelial neoplasia.

Cryotherapy was used to treat 516 patients with various degrees of dysplasia and carcinoma in situ over a 7-year period. Seventy-one percent of patients had either severe dysplasia or carcinoma in situ. In 88% of the patients treated, a single treatment session was successful in eradicating the lesion. Treatment was defined as successful when cytologic and colposcopic findings were negative 1 year after treatment. Five percent of patients were lost to follow-up. The criteria for selection of patients and possible causes of treatment failure are discussed.

Rapid accumulation of intracellular 2-keto-3-deoxy-6-phosphogluconate in an Entner-Doudoroff aldolase mutant results in bacteriostasis.

The accumulation of 2-keto-3-deoxy-6-phosphogluconate, the key intermediate of the Entner-Doudoroff pathway, has long been thought to inhibit growth of bacteria, but careful measurements of 2-keto-3-deoxy-6-phosphogluconate accumulation by growing cells and the correlation of intracellular 2-keto-3-deoxy-6-phosphogluconate levels to growth inhibition had not been made. A system designed for this purpose was developed in Escherichia coli strains, allowing 2-keto-3-deoxy-6-phosphogluconate accumulation to be experimentally induced and measured by extraction of the cell pool. Addition of gluconate to a strain which lacked 2-keto-3-deoxy-6-phosphogluconate aldolase and overproduced 6-phosphogluconate dehydratase resulted in an increase in the intracellular concentration of 2-keto-3-deoxy-6-phosphogluconate from undetectable levels to 2.0 mM within 15 s, as measured by anion-exchange HPLC. The accumulation of 2-keto-3-deoxy-6-phosphogluconate was correlated with an immediate and significant decrease in growth; this inhibition was determined to be bacteriostatic and not bactericidal. It had been proposed that the mechanism of 2-keto-3-deoxy-6-phosphogluconate toxicity involves competitive inhibition of 6-phosphogluconate dehydrogenase and the consequent block of the pentose phosphate pathway. An experiment addressing this hypothesis failed to provide any supporting data.

Attitudes about racism, medical mistrust, and satisfaction with care among African American and white cardiac patients.

The authors examine determinants of satisfaction with medical care among 1,784 (781 African American and 1,003 white) cardiac patients. Patient satisfaction was modeled as a function of predisposing factors (gender, age, medical mistrust, and perception of racism) and enabling factors (medical insurance). African Americans reported less satisfaction with care. Although both black and white patients tended not to endorse the existence of racism in the medical care system, African American patients were more likely to perceive racism. African American patients were significantly more likely to report mistrust. Multivariate analysis found that the perception of racism and mistrust of the medical care system led to less satisfaction with care. When perceived racism and medical mistrust were controlled, race was no longer a significant predictor of satisfaction.

Benign monoclonal gammopathy with IgG anti-DNA, anti-Sm and anti-F(ab')2 activity.

OBJECTIVE: To study anti-DNA idiotypic markers and anti-DNA activity in human monoclonal immunoglobulin proteins. METHODS: Seventy human IgG M-components intentionally selected for cationic electrophoretic characteristics were studied for F4 and 31 anti-DNA idiotypic markers and anti-DNA as well as anti-F(ab')2 antibody activity. RESULTS: Eight of 70 M-components showed significant anti-DNA activity. In two both anti-DNA and anti-F(ab')2 activity occurred together. One IgG-2 kappa M-component showed extremely high anti-ds DNA, anti-Sm, anti-F(ab')2 and anti-Sm/ RNP ELISA activity. Cross inhibition studies showed that each reactive antigen inhibited the other. N-terminal V-region sequencing showed the VH3, VK3 subgroup. Anti-idiotypic rabbit antibody produced against this M-component showed strong reactivity with affinity purified IgG anti-DNA and anti-F(ab')2 from most SLE patients and normal subjects. CONCLUSION: Monoclonal human immunoglobulins may contain multiple autoantibody specificities including anti-DNA; anti-Sm, anti-Sm/RNP, and anti-F(ab')2. Many antibodies with these specificities share common V-region antigens. Such relationships could contribute to idiotypic immune regulation and control.

A monoclonal IgM kappa from a blood group B individual with specificity for alpha-galactosyl epitopes on partially hydrolyzed blood group B substance.

We have characterized a human monoclonal IgM kappa, designated IgMDON, from a blood group B individual. IgMDON is specific for alpha-galactosyl residues on blood group B substance; its fine specificity as defined by hemagglutination, quantitative precipitin, and inhibition ELISA assays was for the defucosylated terminal Gal(alpha 1-3)Gal epitope. Gal(alpha 1-3)Gal epitopes are also found on a variety of normal and pathogenic intestinal bacteria, and polyclonal IgG antibodies with the same specificity are found in the serum of nearly all normal individuals. The specificity of IgMDON was also quite similar to that of a human antiserum, serum 262, obtained by immunizing an individual with blood group B substance that had been subjected to mild acid hydrolysis (BP1). The possible ways whereby IgMDON might have arisen are discussed.

Racial differences in attitudes toward professional mental health care and in the use of services.

Differences in attitudes toward seeking professional mental health care and in the utilization of mental health services were examined by analyzing the second part of the National Comorbidity Survey. Prior to use of services, African Americans were found to have more positive attitudes than whites toward seeking such services, but less likely to use them. After utilization, their attitudes were found to be less positive than those of whites.

Purification of Poly-beta-Hydroxybutyrate by Density Gradient Centrifugation in Sodium Bromide.

Fractionation of fully sporulated cultures of Bacillus thuringiensis by density gradient centrifugation in NaBr produced two bands which were identified as poly-beta-hydroxybutyrate. This technique generated high yields of membrane-bound and unbound granules of exceptional purity and degree of polymerization.

A hypothesis on the role of pressure in the origin of life.

The necessity for long time spans in models on the origin of life leads to a major difficulty in that under the environmental conditions existing today biological macromolecules are inherently unstable. The present hypothesis suggests that life arose under a set of environmental conditions whereby polymerization was thermodynamically favored. In particular, increased pressure when coupled with low water activity and high temperature should stabilize polymer bond formation. Three implications of this pressure stabilization theory are presented: (1) The necessary conditions for stabilization are similar to some of the ecological niches occupied by representatives of the archaebacteria. It is suggested that the harsh and unusual habitats of the archaebacteria reflect in part prebiotic environmental conditions. (2) Biological optical activity would be generated if, for instance, L-L peptide bonds were stabilized to a greater degree than L-D peptide bonds. This type of selective stabilization would provide for the maintenance of molecular asymmetry as well as the creation of molecular asymmetry. (3) Conditions necessary for generating the requisite pressure may concurrently have provided protection from prebiotic ultraviolet radiation.

The energy dependence of detergent resistance in Enterobacter cloacae: a likely requirement for ATP rather than a proton gradient or a membrane potential.

The enteric bacterium Enterobacter cloacae was grown both aerobically and anaerobically in the presence of up to 1% of the anionic detergent sodium dodecyl sulfate (SDS). A continuous energy supply was necessary to maintain cell integrity and cells grown in SDS (0.1-1%) lysed during carbon-limited stationary phase. The respiratory inhibitor KCN (3 mM) caused rapid lysis when added to aerobic, log phase, SDS-containing cultures growing on glucose as the carbon source. However, when the SDS (0.5%) was added 30 min after KCN, lysis did not occur. The likely reason for this discrepancy concerns the cellular ATP levels. In aerobic cells the ATP levels dropped 10- to 15-fold within 1 min of adding KCN and then increased gradually over the next 30 min. Similarly, the addition of 2 mM iodoacetic acid, an inhibitor of glycolysis, to anaerobic, log phase, SDS-containing cultures caused rapid lysis. However, unlike the situation for KCN-treated aerobic cells, lysis still occurred when SDS (0.5%) was added 30 min after addition of iodoacetic acid. The reason for this difference is that in anaerobic cells, ATP levels dropped 10- to 12-fold within 5 min of the addition of iodoacetic acid and then did not increase over the next 30 min. Evidence that the energy requirement was for ATP was provided by uptake experiments with [14C]benzoic acid and alpha-[14C] isoaminobutyric acid that showed that the proton gradient (delta pH) and the membrane potential (delta psi) were the same in cells grown in the presence or absence of SDS.(ABSTRACT TRUNCATED AT 250 WORDS)

Detergent-shock response in enteric bacteria.

Our work on bacterial detergent resistance started with the realization that bacteria growing in a sink full of soap must be resistant to the detergents in that soap. We chose sodium dodecyl sulphate (SDS) as a model detergent and decided to see how much SDS the bacterium growing in the sink could tolerate. The research program thus initiated has shown that bacteria such as Enterobacter cloacae can grow in up to 25% SDS and that SDS-shock proteins constitute c. 8% of the proteins synthesized by SDS-grown Escherichia coli. It has also provided explanations why enteric bacteria are oxidase negative, and how pyrroloquinoline quinone (PQQ) enters the periplasmic space. Finally, for E. coli, it has provided evidence for an alternate, phosphate-limited, aquatic life style which places greater emphasis on the Entner-Doudoroff pathway. Detergent resistance is important both medically and ecologically, e.g. entry of pathogens via bile-salt-containing intestinal tracts and biodegradation of detergent-like pollutants such as those resulting from oil spills. Our current research is focused on SDS-induced modifications of the cytoplasmic membrane and the presence of SDS in the periplasm.