A census of baryons in the Universe from localized fast radio bursts.

More than three-quarters of the baryonic content of the Universe resides in a highly diffuse state that is difficult to detect, with only a small fraction directly observed in galaxies and galaxy clusters1,2. Censuses of the nearby Universe have used absorption line spectroscopy3,4 to observe the 'invisible' baryons, but these measurements rely on large and uncertain corrections and are insensitive to most of the Universe's volume and probably most of its mass. In particular, quasar spectroscopy is sensitive either to the very small amounts of hydrogen that exist in the atomic state, or to highly ionized and enriched gas4-6 in denser regions near galaxies7. Other techniques to observe these invisible baryons also have limitations; Sunyaev-Zel'dovich analyses8,9 can provide evidence from gas within filamentary structures, and studies of X-ray emission are most sensitive to gas near galaxy clusters9,10. Here we report a measurement of the baryon content of the Universe using the dispersion of a sample of localized fast radio bursts; this technique determines the electron column density along each line of sight and accounts for every ionized baryon11-13. We augment the sample of reported arcsecond-localized14-18 fast radio bursts with four new localizations in host galaxies that have measured redshifts of 0.291, 0.118, 0.378 and 0.522. This completes a sample sufficiently large to account for dispersion variations along the lines of sight and in the host-galaxy environments11, and we derive a cosmic baryon density of [Formula: see text] (95 per cent confidence; h70 = H0/(70 km s-1 Mpc-1) and H0 is Hubble's constant). This independent measurement is consistent with values derived from the cosmic microwave background and from Big Bang nucleosynthesis19,20.

Delineation of the pH-Responsive Regulon Controlled by the Helicobacter pylori ArsRS Two-Component System.

Helicobacter pylori encounters a wide range of pH within the human stomach. In a comparison of H. pylori cultured in vitro under neutral or acidic conditions, about 15% of genes are differentially expressed, and corresponding changes are detectable for many of the encoded proteins. The ArsRS two-component system (TCS), comprised of the sensor kinase ArsS and its cognate response regulator ArsR, has an important role in mediating pH-responsive changes in H. pylori gene expression. In this study, we sought to delineate the pH-responsive ArsRS regulon and further define the role of ArsR in pH-responsive gene expression. We compared H. pylori strains containing an intact ArsRS system with an arsS null mutant or strains containing site-specific mutations of a conserved aspartate residue (D52) in ArsR, which is phosphorylated in response to signals relayed by the cognate sensor kinase ArsS. We identified 178 genes that were pH-responsive in strains containing an intact ArsRS system but not in ΔarsS or arsR mutants. These constituents of the pH-responsive ArsRS regulon include genes involved in acid acclimatization (ureAB, amidases), oxidative stress responses (katA, sodB), transcriptional regulation related to iron or nickel homeostasis (fur, nikR), and genes encoding outer membrane proteins (including sabA, alpA, alpB, hopD [labA], and horA). When comparing H. pylori strains containing an intact ArsRS TCS with arsRS mutants, each cultured at neutral pH, relatively few genes are differentially expressed. Collectively, these data suggest that ArsRS-mediated gene regulation has an important role in H. pylori adaptation to changing pH conditions.

A luminous fast radio burst that probes the Universe at redshift 1.

Fast radio bursts (FRBs) are millisecond-duration pulses of radio emission originating from extragalactic distances. Radio dispersion is imparted on each burst by intervening plasma, mostly located in the intergalactic medium. In this work, we observe the burst FRB 20220610A and localize it to a morphologically complex host galaxy system at redshift 1.016 ± 0.002. The burst redshift and dispersion measure are consistent with passage through a substantial column of plasma in the intergalactic medium and extend the relationship between those quantities measured at lower redshift. The burst shows evidence for passage through additional turbulent magnetized plasma, potentially associated with the host galaxy. We use the burst energy of 2 × 1042 erg to revise the empirical maximum energy of an FRB.

A H+-gated urea channel: the link between Helicobacter pylori urease and gastric colonization.

Acidic media trigger cytoplasmic urease activity of the unique human gastric pathogen Helicobacter pylori. Deletion of ureI prevents this activation of cytoplasmic urease that is essential for bacterial acid resistance. UreI is an inner membrane protein with six transmembrane segments as shown by in vitro transcription/translation and membrane separation. Expression of UreI in Xenopus oocytes results in acid-stimulated urea uptake, with a pH profile similar to activation of cytoplasmic urease. Mutation of periplasmic histidine 123 abolishes stimulation. UreI-mediated transport is urea specific, passive, nonsaturable, nonelectrogenic, and temperature independent. UreI functions as a H+-gated urea channel regulating cytoplasmic urease that is essential for gastric survival and colonization.

Local pH elevation mediated by the intrabacterial urease of Helicobacter pylori cocultured with gastric cells.

Helicobacter pylori resists gastric acidity by modulating the proton-gated urea channel UreI, allowing for pH(out)-dependent regulation of urea access to intrabacterial urease. We employed pH- and Ca(2+)-sensitive fluorescent dyes and confocal microscopy to determine the location, rate, and magnitude of pH changes in an H. pylori-AGS cell coculture model, comparing wild-type bacteria with nonpolar ureI-deletion strains (ureI-ve). Addition of urea at pH 5.5 to the coculture resulted first in elevation of bacterial periplasmic pH, followed by an increase of medium pH and then pH in AGS cells. No change in periplasmic pH occurred in ureI-deletion mutants, which also induced a slower increase in the pH of the medium. Pretreatment of the mutant bacteria with the detergent C(12)E(8) before adding urea resulted in rapid elevation of bacterial cytoplasmic pH and medium pH. UreI-dependent NH(3) generation by intrabacterial urease buffers the bacterial periplasm, enabling acid resistance at the low urea concentrations found in gastric juice. Perfusion of AGS cells with urea-containing medium from coculture at pH 5.5 did not elevate pH(in) or [Ca(2+)](in), unless the conditioned medium was first neutralized to elevate the NH(3)/NH(4)(+) ratio. Therefore, cellular effects of intrabacterial ammonia generation under acidic conditions are indirect and not through a type IV secretory complex. The pH(in) and [Ca(2+)](in) elevation that causes the NH(3)/NH(4)(+) ratio to increase after neutralization of infected gastric juice may contribute to the gastritis seen with H. pylori infection.

Epidemiologic evidence showing that human papillomavirus infection causes most cervical intraepithelial neoplasia.

BACKGROUND: Experimental studies have provided strong evidence that human papillomavirus (HPV) is the long-sought venereal cause of cervical neoplasia, but the epidemiologic evidence has been inconsistent. PURPOSE: Given improvements in HPV testing that have revealed a strong link between sexual activity history and cervical HPV infection, we conducted a large case-control study of HPV and cervical intraepithelial neoplasia (CIN) to evaluate whether sexual behavior and the other established risk factors for CIN influence risk primarily via HPV infection. METHODS: We studied 500 women with CIN and 500 control subjects receiving cytologic screening at Kaiser Permanente, a large prepaid health plan, in Portland, Ore. The established epidemiologic risk factors for CIN were assessed by telephone interview. We performed HPV testing of cervicovaginal lavage specimens by gene amplification using polymerase chain reaction with a consensus primer to target the L1 gene region of HPV. Unconditional logistic regression analysis was used to estimate relative risk of CIN and to adjust the epidemiologic associations for HPV test results to demonstrate whether the associations were mediated by HPV. RESULTS: The case subjects demonstrated the typical epidemiologic profile of CIN: They had more sex partners, more cigarette smoking, earlier ages at first sexual intercourse, and lower socioeconomic status. Statistical adjustment for HPV infection substantially reduced the size of each of these case-control differences. Seventy-six percent of cases could be attributed to HPV infection; the results of cytologic review suggested that the true percentage was even higher. Once HPV infection was taken into account, an association of parity with risk of CIN was observed in both HPV-negative and HPV-positive women. CONCLUSION: The data show that the great majority of all grades of CIN can be attributed to HPV infection, particularly with the cancer-associated types of HPV. IMPLICATIONS: In light of this conclusion, the investigation of the natural history of HPV has preventive as well as etiologic importance.

Detection of human papillomavirus DNA in cytologically normal women and subsequent cervical squamous intraepithelial lesions.

BACKGROUND: Human papillomavirus (HPV) infection has been strongly associated with cervical carcinoma and its cytologic precursors, squamous intraepithelial lesions (SIL). We investigated the risk of SIL prospectively following polymerase chain reaction (PCR)-based DNA testing for a wide range of genital HPV types in a cohort of initially cytologically normal women, to clarify the role of HPV in the etiology of SIL. METHODS: Starting in April 1989, 17,654 women who were receiving routine cytologic screening at Kaiser Permanente (Portland, OR) were followed for the development of incident SIL. During follow-up, 380 incident case patients and 1037 matched control subjects were eligible for this nested case-control study. Cervical lavages collected at enrollment and, later, at the time of case diagnosis (or the corresponding time for selection of control subjects) were tested for HPV DNA using a PCR-based method. The data were analyzed as contingency tables with two-sided P values or, for multivariable analyses, using odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: In comparison with initially HPV-negative women, women who tested positive for HPV DNA at enrollment were 3.8 times (95% CI = 2.6-5.5) more likely to have low-grade SIL subsequently diagnosed for the first time during follow-up and 12.7 times more likely (95% CI = 6.2-25.9) to develop high-grade SIL. At the time of diagnosis, the cross-sectional association of HPV DNA and SIL was extremely strong (OR = 44.4 and 95% CI = 24.2-81.5 for low-grade SIL and OR = 67.1 and 95% CI = 19.3-233.7 for high-grade SIL). HPV16 was the virus type most predictive of SIL, even low-grade SIL. CONCLUSIONS: These findings are consistent with the hypothesis that HPV infection is the primary cause of cervical neoplasia. Furthermore, they support HPV vaccine research to prevent cervical cancer and efforts to develop HPV DNA diagnostic tests.

Interleukin 2 production in vitro by peripheral lymphocytes in response to human papillomavirus-derived peptides: correlation with cervical pathology.

Human papillomavirus (HPV) is believed to be the major cause of cervical cancer. To investigate whether a cellular immune response, especially a T helper type 1 response, is related to the natural defense against HPV-related cervical lesions, the interleukin 2 response of peripheral blood lymphocytes in vitro to overlapping peptides from HPV-16 E6 and E7 oncoproteins was compared with the degree of cervical cytological abnormality among 140 women in a cross-sectional study. We compared 66 women diagnosed with low-grade squamous intraepithelial lesions (LSIL), 21 with high-grade squamous intraepithelial lesions (HSIL), and 28 with invasive cervical cancer with 25 women who were cytologically normal but previously HPV-16 DNA positive. The fraction showing strong interleukin 2 production against HPV-16 peptides was greatest among cytologically normal women (35%) and declined with increasing disease severity [LSIL] (20%), HSIL, (17%), and cancer patients (7%); X2 test P for the trend = 0.02], whereas the responses against a recall influenza antigen were not significantly different among groups. Our finding suggests that a T helper lymphocyte type 1 response to HPV antigens is associated with disease status. This result may reflect a targeted effect of the disease on immune function or a protective effect of the immune response against disease progression.

The site of acid secretion in the mammalian parietal cell.

Initiation of acid secretion in the gastric mucosa is accompanied by a morphological transformation in which the acid pump, the H+/K(+)-ATPase, translocates from a cytoplasmic vesicular location to the secretory surface lining the canaliculi. Associated with the morphological changes, activation of K+ and Cl- pathways are necessary to supply K+ to the extracytoplasmic face of the pump. Although the pump in the secretory membrane is known to secrete acid, it is not known whether activation of the KCl pathway occurs in the tubulovesicular membrane prior to the formation of the canaliculus, or when the pump is in the secretory membrane. The cellular site of activation of acid secretion in the rabbit gastric parietal cell was investigated using the covalent binding of [3H]omeprazole as a probe of acid secretion in rabbit gastric glands that were undergoing stimulation in vitro. This compound depends on an acidic environment for activation and covalent binding to the H+/K(+)-ATPase. Electron microscopic autoradiography showed that activation of the enzyme occurred only when it was present in the canalicular membrane and not when it was present in the cytoplasmic tubulovesicular membrane. Hence there is likely to be a physical separation of K+ and/or Cl- pathways from the ATPase in the resting cell, and stimulation of acid secretion is dependent on colocalization of these pathways in the canalicular membrane.

Determination of the sidedness of the C-terminal region of the gastric H,K-ATPase alpha subunit.

It cannot be predicted from hydropathy analysis whether the C-terminal end of the alpha subunit of the gastric H,K-ATPase is cytoplasmic or extracytoplasmic. The sideness of the C-terminal amino acids was determined by taking advantage of the two C-terminal tyrosines in the primary sequence of the enzyme. Intact, cytoplasmic side out vesicles derived from hog gastric mucosa or detergent solubilized vesicles were iodinated by the lactoperoxidase method and then the C-terminal amino acids hydrolyzed by carboxypeptidase Y. The alpha and beta subunits were separated by SDS gel electrophoresis. The level of iodination of the alpha subunit following solubilization was about three fold greater than when intact vesicles were iodinated, and the beta subunit was iodinated only when solubilized enzyme was used. Carboxypeptidase Y removed 28 +/- 4% of the radioactivity from the alpha subunit iodinated in intact vesicles. These data are consistent with a cytoplasmic location of the C-terminal amino acids of the alpha subunit and with a mostly extracytoplasmic location of the amino acids of the beta subunit.

Colloidal bismuth subcitrate impedes proton entry into Helicobacter pylori and increases the efficacy of growth-dependent antibiotics.

BACKGROUND: Successful eradication of Helicobacter pylori is becoming more difficult, mainly due to emerging antibiotic resistance. Treatment regimens containing bismuth have increased efficacy, but the mechanism is unknown. Helicobacter pylori is a neutralophile adapted to survive the acidic gastric environment via acid acclimation, but demonstrates more robust growth at neutral pH. Many antibiotics used to treat H. pylori rely on bacterial growth. AIM: To investigate the mechanism of increased efficacy of bismuth-containing H. pylori treatment regimens. METHODS: RNAseq and qPCR, urease activity in permeabilised and intact bacteria, internal pH and membrane potential were measured with and without colloidal bismuth subcitrate (CBS). Bacterial survival was assessed with CBS and/or ampicillin. RESULTS: Genes involved with metabolism and growth were upregulated in the presence of CBS at acidic pH. Urease activity of permeabilised H. pylori at pH 7.4 and 4.5 decreased in the presence of CBS, but intact urease activity decreased only at acidic pH. The fall in cytoplasmic pH with external acidification was diminished by CBS. The increase in membrane potential in response to urea addition at acidic medium pH was unaffected by CBS. The impact of CBS and ampicillin on H. pylori survival was greater than either agent alone. CONCLUSIONS: Bismuth is not acting directly on urease or the urea channel. Colloidal bismuth subcitrate impedes proton entry into the bacteria, leading to a decrease in the expected fall in cytoplasmic pH. With cytoplasmic pH remaining within range for increased metabolic activity of a neutralophile, the efficacy of growth-dependent antibiotics is augmented.

The binding selectivity of vonoprazan (TAK-438) to the gastric H+, K+ -ATPase.

BACKGROUND: The gastric H(+) ,K(+) -ATPase is the preferred target for acid suppression. Until recently, the only drugs that effectively inhibited this ATPase were the proton pump inhibitors (PPIs). PPIs are acid-activated prodrugs that require acid protection. Once acid-activated, PPIs bind to cysteines of the ATPase, resulting in covalent, long-lasting inhibition. The short plasma half-life of PPIs and continual de novo synthesis of the H(+) ,K(+) -ATPase result in difficulty controlling night-time acid secretion. A new alternative to PPIs is the pyrrolo-pyridine, vonoprazan (TAK-438), a potassium-competitive acid blocker (PCAB) that does not require acid protection. In contrast to other PCABs, vonoprazan has a long duration of action, resulting in 24-h control of acid secretion, a high pKa of 9.37 and high affinity (Ki = 3.0 ηmol/L). AIM: To determine binding selectivity of vonoprazan for the gastric H(+) ,K(+) -ATPase and to explain its slow dissociation. METHODS: Gastric gland and parietal cell binding of vonoprazan was determined radiometrically. Molecular modelling explained the slow dissociation of vonoprazan from the H(+) ,K(+) -ATPase. RESULTS: Vonoprazan binds selectively to the parietal cell, independent of acid secretion. Vonoprazan binds in a luminal vestibule between the surfaces of membrane helices 4, 5 and 6. Exit of the drug to the lumen is hindered by asp137 and asn138 in the loop between TM1 and TM2, which presents an electrostatic barrier to movement of the sulfonyl group of vonoprazan. This may explain its slow dissociation from the H(+) ,K(+) -ATPase and long-lasting inhibition. CONCLUSION: The binding model provides a template for design of novel potassium-competitive acid blockers.

Evidence for at least two distinct groups of humoral immune reactions to papillomavirus antigens in women with squamous intraepithelial lesions.

Serological markers of squamous intraepithelial lesions (SILs), the precursors of cervical cancer, have not been studied extensively. To screen for antibody responses that might be associated with SILs, we measured IgG and/or IgA to nine antigens based on papillomaviruses, the infectious cause of SIL and cervical cancer, using an ELISA format. Cases were 59 women with low grade SIL (LSIL) and 38 with high grade SIL (HSIL). Controls were 50 women chosen to minimize the possibility that they ever had SILs [individuals who had no history of SIL and repeatedly tested negative for cervical human papillomavirus (HPV) DNA], frequency age-matched to cases. The data showed that five antibodies had strong positive associations with SILs and that one was inversely related to SILs. By studying these antibodies in pairs, furthermore, we found that case-control differences were enhanced. In particular, the combination of IgG to an epitope in the E6 protein of HPV 16 (E6:10) and IgA to HPV 16 virus-like particles (VLPs) was detected in 53% of LSILs and 65% of HSILs but only 9% of controls. These same responses were both negative in just 6% of LSILs and zero HSILs, compared to 59% of controls. Notably, E6:10 IgG and HPV 16 VLP IgA were not correlated with each other, and the other antibody responses positively associated with SILs could be broken into two groups: those correlated with E610 IgG and those correlated with HPV 16 VLP IgA. Overall, the data suggest that several papillomavirus antibodies may be strongly related to SILs, and that they can be divided into at least two independent groups of humoral immune reactions.

Human leukocyte antigen class I/II alleles and development of human papillomavirus-related cervical neoplasia: results from a case-control study conducted in the United States.

The host immune response to human papillomaviruses (HPVs) is believed to be an important determinant of progression of HPV-associated cervical neoplasia. Human leukocyte antigens (HLAs) are important in the presentation of foreign antigens to the immune system. Previous studies have suggested a possible association between HLA and cervical neoplasia, but the specific alleles found to be associated with disease have varied between studies. To further evaluate this issue, we conducted a nested case-control study within a 24,000-woman cohort study in the United States. A total of 711 women were selected for the study: 141 women diagnosed with high-grade squamous intraepithelial lesions (HSILs) of the cervix; 202 women diagnosed with low-grade SILs (LSILs); 166 women with no history of cervical neoplasia, but evidence of HPV-16 infection; and 202 women with no history of cervical abnormalities and who were HPV negative during follow-up as part of our cohort. Cervicovaginal lavage samples collected from participants were used for HPV testing by L1 consensus primer PCR and the Hybrid Capture tube test methods. DNA extracted from these same lavage samples were used for PCR-based HLA genotyping. Our results suggest a positive association between HLA B7 and HLA DQB1*0302 and disease. A negative association with disease was observed for HLA DRB1*1501-DQB1*0602 and DRB1*13. Associations were strongest when analyses were restricted to HPV-16-positive cases as follows. Compared with women who were cytologically normal and HPV negative, HLA B7 was associated with a 1.5-fold increased risk of HPV/LSIL [95% confidence interval (CI) = 0.95-2.5] and a 2.5-fold increased risk of HSIL (95% CI = 1.2-5.1). HLA DQB1*0302 was associated with a 1.5-fold increased risk of HPV/LSIL (95% CI = 0.94-2.4) and a 1.7-fold increased risk of HSIL (95% CI = 0.84-3.5). HLA DRB1*1501-DQB1*0602 was associated with a decreased risk of HSIL [relative risk (RR) = 0.21; 95% CI = 0.07-0.62]. HLA DRB1*13 was associated with a decreased risk of HPV/LSIL (RR = 0.78; 95% CI = 0.51-1.2) and HSIL (RR = 0.63; 95% CI = 0.30-1.3). Individuals who were either homozygous for DQB1*0302 or carriers of both B7 and DQB1*0302 were found to be at highest risk of disease (RR = 4.5, 95% CI = 1.5-14 for HPV/LSIL; and RR = 9.0, 95% CI = 2.4-34 for HSIL). No synergistic effect was observed for the alleles found to be associated with reduced risk of cervical neoplasia. Our findings support previous studies that have found HLA B7 and DQB1*0302 to be positively associated with cervical neoplasia and are consistent with those that have suggested that DRB1*13 is negatively associated with disease, but do not confirm previous assertions that DRB1*1501-DQB1*0602 increases the risk of cervical disease.

Immune activation in cervical neoplasia: cross-sectional association between plasma soluble interleukin 2 receptor levels and disease.

In a previous study (Tsukui et al., Cancer Res., 56: 3967-3974, 1996), we observed an inverse association between degree of cervical neoplasia and interleukin (IL) 2 production by peripheral blood mononuclear cells in response to human papillomavirus (HPV) 16 E6 and E7 peptides in vitro. This suggested that a Th1-mediated cellular immune response might be important in host immunological control of HPV infection and that a lack of such a response might predispose to progression of cervical disease. To follow up on these findings, we have conducted a cross-sectional study of women with various degrees of cervical neoplasia to investigate the association between overall immune activation and cervical disease. A total of 235 women were recruited into our study; 120 of these women were participants in our previous study in which IL-2 production in response to HPV-16-specific peptides was measured. The study population included 34 women with invasive cancer, 62 women with high-grade squamous intraepithelial lesions (HSILs), and 105 women with low-grade squamous intraepithelial lesions (LSILs). In addition, 34 cytologically normal women with no past history of squamous intraepithelial lesions despite confirmed HPV-16 infection in the 5 years preceding the study were selected as controls. As our measure of overall immune activation, serum samples obtained from study participants were tested for soluble IL-2 receptor (sIL-2R) level using an ELISA method. The mean sIL-2R levels were found to increase with increasing disease severity (Ptrend = 0.0002). Among cytologically normal, HPV-exposed women, the mean receptor level in serum was 465.8 units/ml compared to 467.6 units/ml among LSIL subjects, 514.9 units/ml among HSIL subjects, and 695.5 units/ml among women with invasive cervical cancer. Similarly, the proportion of women with elevated sIL-2R levels (defined as > or = 450 units/ml) increased with increasing disease severity from 35.2% among normal study subjects to 70.6% among cancer patients (Ptrend = 0.003). Among the subgroup of subjects for whom in vitro IL-2 production in response to HPV-16-specific peptides was measured, we examined the association between in vitro IL-2 production and serum levels of sIL-2R. sIL-2R levels were higher, on average, among those women who were positive in our IL-2 production assay compared to those who were negative, but the differences did not reach statistical significance (P > 0.05). We also observed a trend of increasing sIL-2R level with increasing disease severity both in women who were positive and in women who were negative for our IL-2 production assay, but the trend was only significant among those who were negative for IL-2 production (Ptrend = 0.01). Results from our studies suggest that although the immune system of women with cervical neoplasia is nonspecifically activated as disease severity increases, the ability of those women with HSILs or cancer to mount a Th1-mediated immune response to HPV peptides appears to decrease compared to women with LSILs or normal women infected with HPV. Increased overall activation along with decreased Th1 immune response among women with increasing cervical disease severity might be explained by an increased Th2-mediated immune response, a response that we hypothesize is ineffective in controlling the viral infection and its early cytological manifestations. Future studies should directly assess Th2-mediated responses to confirm this hypothesis. Also, future efforts should be aimed at determining whether the associations observed are causally related to disease progression or an effect of the disease.

Glutathione peroxidase of calf trabecular meshwork.

Glutathione peroxidase was extracted from calf trabecular meshwork. The kinetics of this enzyme were examined, varying the substrates hydrogen peroxide (H2O2), tert- butylhydroperoxide ( tBHP ), and glutathione. The activity of the enzyme in nonpurified homogenates was 596 nmole H2O2 reduced/min/gm wet weight and 680 nmole tBHP reduced/min/gm wet weight (27-28 nmole peroxide reduced/min/mg protein). The apparent Michaelis--Menten constants for H2O2, tBHP , and GSH were 0.012, 0.102, and 2.89 mM, respectively. These data, together with published levels of glutathione in trabecular meshwork, suggest that the trabecular endothelial cell actively detoxifies H2O2.

Influence of mercurial sulfhydryl agents on aqueous outflow pathways in enucleated eyes.

Enucleated calf and primate eyes were perfused with either p-chloromercuribenzene sulfonate (PCMBS) or p-chloromercuribenzene (PCMB). Both caused a decrease in aqueous outflow that did not result from inhibition of glycolysis in trabecular cells. Morphologic studies of PCMBS-treated primate eyes suggested that the reduction in aqueous outflow occurred as the result of cellular swelling in the trabecular meshwork and, particularly, in the juxtacanalicular connective tissue. These findings suggest that changes in cell volume may influence trabecular outflow resistance and that mercurial-sensitive membrane sulfhydryl groups could participate in the regulation of aqueous outflow.

A seroepidemiologic study of HPV infection and incident cervical squamous intraepithelial lesions.

The seroepidemiology of genital human papillomavirus (HPV) and incident cervical squamous intraepithelial lesions (SIL) was studied in subjects selected from a large cohort monitored for the development of SIL. Serum IgG and IgA responses to 10 epitopes derived from HPV were measured in 21 incident cases of SIL and 56 matched controls. Cases showed elevated antibody (i.e., IgG and/or IgA) seroprevalence to 245:16, a peptide antigen derived from the E2 open reading frame of HPV 16 (OR = 5.76; 95% CI: 1.24, 26.81). The type of HPV DNA detected in cervical lavage specimens had no effect on this relationship. Multivariate analysis also showed that IgG to 245:6, an analogous peptide derived from HPV 6, was negatively associated with SIL (OR = 0.12; 95% CI: 0.02, 0.77). No other antibody responses tested were associated with SIL. Furthermore, no antibody responses were positively associated with detection of HPV DNA in women without SIL. We conclude that incident SIL is positively associated with antibody to an epitope derived from the E2 region of HPV 16, and negatively associated with antibody to an analogous peptide derived from HPV 6. The seroepidemiology of incident SIL appears different from that of cervical HPV infection in the absence of SIL.

Optimization and testing of mass spectral library search algorithms for compound identification.

Five algorithms proposed in the literature for library search identification of unknown compounds from their low resolution mass spectra were optimized and tested by matching test spectra against reference spectra in the NIST-EPA-NIH Mass Spectral Database. The algorithms were probability-based matching (PBM), dot-product, Hertz et al. similarity index, Euclidean distance, and absolute value distance. The test set consisted of 12,592 alternate spectra of about 8000 compounds represented in the database. Most algorithms were optimized by varying their mass weighting and intensity scaling factors. Rank in the list of candidatc compounds was used as the criterion for accuracy. The best performing algorithm (75% accuracy for rank 1) was the dot-product function that measures the cosine of the angle between spectra represented as vectors. Other methods in order of performance were the Euclidean distance (72%), absolute value distance (68%) PBM (65%), and Hertz et al. (64%). Intensity scaling and mass weighting were important in the optimized algorithms with the square root of the intensity scale nearly optimal and the square or cube the best mass weighting power. Several more complex schemes also were tested, but had little effect on the results. A modest improvement in the performance of the dot-product algorithm was made by adding a term that gave additional weight to relative peak intensities for spectra with many peaks in common.

Review article: the control of gastric acid and Helicobacter pylori eradication.

This review focuses on the gastric acid pump as a therapeutic target for the control of acid secretion in peptic ulcer and gastro-oesophageal reflux disease. The mechanism of the proton pump inhibitors is discussed as well as their clinical use. The biology of Helicobacter pylori as a gastric denizen is then discussed, with special regard to its mechanisms of acid resistance. Here the properties of the products of the urease gene clusters, ureA, B and ureI, E, F, G and H are explored in order to explain the unique location of this pathogen. The dominant requirement for acid resistance is the presence of a proton gated urea transporter, UreI, which increases access of gastric juice urea to the intrabacterial urease 300-fold. This enables rapid and continuous buffering of the bacterial periplasm to approximately pH 6.0, allowing acid resistance and growth at acidic pH in the presence of 1 mM urea. A hypothesis for the basis of combination therapy for eradication is also presented.