bluuebunny/crossref_metadata_2025 huggingface dataset:
Geophysical evidence for karst formation associated with offshore groundwater transport: An example from North Carolina
Authors: Evans Rob L. , Lizarralde Dan
Published: August 2003

Marine geophysical data from Long Bay, North Carolina, involving a novel combination of electromagnetic and high‐resolution Chirp seismics, show evidence of submarine karst formation associated with what has been inferred to be a site of high‐flux submarine groundwater discharge (SGD) a substantial distance offshore. Recently observed temperature and chemical signals from wells in this area provide the basis for the interpretation of the high‐flux SGD here, and they also suggest a terrestrial source for the groundwater and thus a potentially important route for nutrient transport to the oceans. Our data indicate that karstification is localized to the high‐flux zone, and we suggest that mixing of the chemically distinct (but saline) groundwater with seawater has resulted in the karstification. As karstification increases permeability and flux, a positive feedback would tend to progressively enhance submarine groundwater discharge. Our data reveal a significant local anomaly in apparent porosity: a dense block that may have initiated the local focusing of groundwater flow. Conditions favorable to the formation of similar locally punctuated sites of high‐flux SGD are likely to exist along the mid to inner shelf of the southeastern United States, where carbonate aquifers are prevalent.
Tomographic investigations of temporal variations of the ionospheric electron density and the implied fluxes
Authors: Kunitsyn V. E. , Andreeva E. S. , Franke S. J. , Yeh K. C.
Published: August 2003

A new technique is introduced for determining plasma fluxes using tomographic images of ionospheric electron density. Pairs of images are used to estimate the time derivative of the F‐region electron density in the region of the northern equatorial anomaly at 120°E longitude. Characteristics of temporal variations are described, and two different methods are used to infer electron fluxes from the measured time derivaties. The height‐dependent latitudinally‐averaged vertical flux and a 2D “potential” flux are derived based on reasonable assumed boundary conditions. Examples illustrate that average vertical plasma fluxes in the local morning and evening hours are upward and downward, respectively, with peak magnitudes on the order of 109 cm−2s−1. The 2D plasma fluxes in a meridional cross‐section through the equatorial anomaly are calculated, and clearly illustrate the characteristic flow associated with the equatorial fountain effect.
Three‐dimensional nonlinear evolution of equatorial ionospheric spread‐F bubbles
Authors: Keskinen M. J. , Ossakow S. L. , Fejer B. G.
Published: August 2003

Using numerical simulation techniques, we present the first study of the three‐dimensional nonlinear evolution of an equatorial spread‐F bubble. The background ionosphere used to initialize the bubble evolution is computed using a time‐dependent first‐principles equatorial plasma fountain model together with a prereversal enhancement vertical drift model. We find that finite parallel conductivity effects slow down both the linear and nonlinear bubble evolution compared to the two‐dimensional evolution. In addition we find that bubble‐like structures with extremely sharp density gradients can be generated off the equator at equatorial anomaly latitudes in agreement with recent observations.
Ecosystem‐scale measurements of nitrous oxide fluxes for an intensely grazed, fertilized grassland
Authors: Scanlon Todd M. , Kiely Ger
Published: August 2003

An eddy covariance (EC) system with a tunable diode laser trace gas analyzer was used in a field setting in Ireland to measure N2O emissions on a continuous basis over an eight‐month period, spanning a range of seasonal conditions. Intensely‐grazed grassland fields within the footprint area of the EC sensors were subject to chemical fertilizer and slurry applications in order to boost grassland yield, and the amounts of these applications were documented by the farmers on a monthly basis. Three major emission events, covering a timeframe of 16 days (6.6% of the measurement period) contributed to over half (51.1%) of the observed cumulative flux. Two of these events occurred during the summer, while the third occurred during the winter, with vastly different soil moisture and soil temperature conditions associated with these times of the year. The type of N applications (fertilizer vs. slurry), soil moisture and temperature status had implications for controlling the short‐term rates of N2O emissions. Cumulative N2O emissions, however, were driven by fertilizer and slurry N applications, as the emission factor of approximately 3.0% displayed consistency throughout the eight‐month period.
Tectonic control of ocean island basalt sources on São Miguel, Azores?
Authors: Haase Karsten M. , Beier Christoph
Published: August 2003

The calderas of the two isotopically distinct volcanoes Sete Cidades and Agua de Pau on São Miguel are only 30 km apart. Sete Cidades lavas generally have 87Sr/86Sr < 0.7038 while Agua de Pau lavas have 87Sr/86Sr > 0.7040. Two overlapping rift zones exist between the two volcanoes and the lava compositions show that each rift zone is connected to the neighbouring volcano. Limited mixing between the volcanic systems implies separate ascent paths and magma sources with diameters of ∼20 km. The two volcanic systems follow contrasting directions; the Sete Cidades volcanic rift strikes NW parallel to the extensional Terceira Rift, while the Agua de Pau volcanic rift zone strikes E‐W. The covariation of magma sources and lithospheric tectonics may suggest that the tectonic structure of the lithosphere controls the mantle upwelling beneath São Miguel.
Advances in satellite radiometry for the surveillance of surface temperatures, ocean eddies and upwelling processes in the Gulf of Mexico using GOES‐8 measurements during summer
Authors: Walker Nan , Myint Soe , Babin Adele , Haag Alaric
Published: August 2003

GOES‐8 satellite infrared (IR) measurements have been under‐utilized in oceanographic research, although they provide several advantages over measurements from other sensors such as the NOAA AVHRR. Frequent coverage (48 times/day) over large regions, low noise in the mid‐ IR channel, and sole use of nighttime data have enabled the development of improved techniques for producing “de‐clouded” images and calculating accurate SSTs (with RMS errors <0.5°C), over cloudy and humid regions such as the Gulf of Mexico. Animations of SST composite images reveal movements of the Loop Current, its frontal eddies and coastal upwelling even during summer months. GOES‐12 and future GOES imagers for the next decade are missing the 12 μm channel; however, this study demonstrates that the mid‐IR channel is even more useful than previously thought.
Alfvén wave dissipation via electron energization
Authors: Wright Andrew N. , Allan W. , Damiano Peter A.
Published: August 2003

It has recently been noted that FAST (Fast Auroral SnapshoT) mission data of auroral current systems associated with Alfvén waves has an electron kinetic energy flux density that is similar to the Poynting vector [Chaston et al., 2002]. In Ultra‐Low‐Frequency (ULF) wave theory, which considers global wave modes of the magnetosphere (with frequency 1–5 mHz), the traditional dissipation mechanism is taken to be Joule heating associated with ionospheric currents that are fed by the Poynting vector. Hence FAST observations indicate that electron acceleration can supply an additional sink of energy that is of similar magnitude to the traditional one. In this letter we use typical Pc5 parameters to estimate the importance of electron acceleration as a sink of Alfvén wave energy for these global waves. We find that the electron dynamics must be treated nonlinearly, and that electron acceleration drains a similar amount of energy from the Alfvén wave fields as ionospheric dissipation, and for some events may actually exceed the latter.
The role of marsh‐dominated heterotrophic continental margins in transport of CO2 between the atmosphere, the land‐sea interface and the ocean
Authors: Cai Wei‐Jun , Wang Zhaohui Aleck , Wang Yongchen
Published: August 2003

Recent air‐to‐sea CO2 flux measurements at several major continental shelves suggest that shelves may act as a one‐way pump and absorb atmospheric CO2 into the ocean. The U.S. South Atlantic Bight (SAB) contrasts these findings in that it acts as a source of CO2 to the atmosphere while simultaneously exporting dissolved inorganic carbon (DIC) to the open ocean. The shelf‐wide heterotrophy and carbon exports in the SAB are subsidized by the export of organic carbon from the abundant intertidal marshes, which are a sink for atmospheric CO2. It is proposed here that the SAB represents a marsh‐dominated heterotrophic ocean margin as opposed to river‐dominated autotrophic margins. Based on this and other studies, DIC export flux from margins to the open ocean must be significant in the overall global ocean carbon budget.
Elastic thickness and isostatic coherence anisotropy in the South Indian Peninsular Shield and its implications
Authors: Stephen Jimmy , Singh S. B. , Yedekar D. B.
Published: August 2003

We present measurements of the mechanical strength of the lithosphere of the South Indian Peninsular Shield (SIPS). Values of Effective Elastic Thickness (Te) were obtained from azimuthally averaged coherence measurements γ2(∣k∣) between Bouguer gravity and topography using a multitaper method (MTM) and a mirrored periodogram method (MPM). Values of Te from MTM (11–16 km) are consistently lower than those from MPM (20–31 km) and are contained within the seismogenic thickness (Ts), substantiating earlier measurements in shield regions that have been tectonically inactive for a long time. The 2D coherence function γ2(k) calculated with the MTM reveals little mechanical anisotropy in the SIPS. We conduct analyses of different provinces within the SIPS and show how the results correlate with maximum horizontal stress orientations (σHmax) and heat flow measurements. Local processes appear to influence the strength of the SIPS lithosphere more profoundly than processes occurring at the plate boundary.
On the source location of low‐frequency heliospheric radio emissions
Authors: Kurth W. S. , Gurnett D. A.
Published: August 2003

We used a combination of three different types of source localization to determine the two‐dimensional source positions for low‐frequency heliospheric radio emissions in ecliptic coordinates. These techniques include time of flight, rotating dipole direction finding, and a comparison of received power from two widely spaced receivers. Most of the source locations are within a few tens of degrees of the heliospheric nose, although some sources are located as far as 90° from the nose. The distribution is roughly linear and aligned generally parallel to the galactic plane. We conclude that the magnetic field in the local interstellar medium is the only obvious means by which to impose an asymmetry to the set of source locations about the nose; it is likely these measurements confirm that the previously proposed model for the galactic magnetic field with a primarily longitudinal orientation parallel to the galactic plane is present just upstream of the heliosphere. The apparent sizes of the radio sources range from very small (a few degrees at the most) to a few tens of degrees. In a couple of cases the source half‐angle could approach 80 degrees. We suggest that the true source size is quite small and that the larger sizes found here are likely due to scattering in the intervening medium. The fact that the apparent source size varies considerably implies that scattering in the outer heliosphere is a function of time, position, or both.
Voyager 1/UVS Lyman α glow data from 1993 to 2003: Hydrogen distribution in the upwind outer heliosphere
Authors: Quémerais Eric , Bertaux Jean‐Loup , Lallement Rosine , Sandel Bill R. , Izmodenov Vlad
Published: August 2003

We report the latest study of the UVS/Voyager 1 Lyman α data obtained between 1993 and 2003. These data show that the radial variation of the intensities measured close to the upwind direction has changed abruptly at the end of 1997 when the spacecraft was at a distance larger than 70 AU from the Sun. The coefficient α of the power law describing the intensity as a function of solar distance has changed from a value of −1.58 ± 0.02 between 1993 to 1997 to a value of −0.22 ± 0.07 after 1998. This change is not compatible with current stationary models of the hydrogen distribution whether they include the effects of the heliospheric interface or not. We discuss possible causes for this change including temporal variations of the hydrogen distribution near the heliopause.
Evidence for slowdown in stratospheric ozone loss: First stage of ozone recovery
Authors: Newchurch M. J. , Yang Eun‐Su , Cunnold D. M. , Reinsel Gregory C. , Zawodny J. M. , Russell James M.
Published: August 2003

Global ozone trends derived from the Stratospheric Aerosol and Gas Experiment I and II (SAGE I/II) combined with the more recent Halogen Occultation Experiment (HALOE) observations provide evidence of a slowdown in stratospheric ozone losses since 1997. This evidence is quantified by the cumulative sum of residual differences from the predicted linear trend. The cumulative residuals indicate that the rate of ozone loss at 35–45 km altitudes globally has diminished. These changes in loss rates are consistent with the slowdown of total stratospheric chlorine increases characterized by HALOE HCl measurements. These changes in the ozone loss rates in the upper stratosphere are significant and constitute the first stage of a recovery of the ozone layer.
Seasonal variation of free tropospheric aerosol particles at Mt. Tateyama, central Japan
Authors: Osada K. , Kido M. , Iida H. , Matsunaga K. , Iwasaka Y. , Nagatani M. , Nakada H.
Published: August 2003

Number‐size distribution of atmospheric aerosol particles and O3 concentration were measured at Murododaira (36.6N, 137.6E, 2450 m above sea level (asl)) on the western flank of Mt. Tateyama in central Japan from January 1999 to November 2002. This study used nighttime data from 2400 to 0500 hours (local time) on the basis of analysis of their diurnal variation to characterize free tropospheric aerosols and O3 over Japan. The O3 concentration shows small variability (standard deviation of 4 ppbv) with the mean value of 40 ppbv in winter (October to February), large variability (8 ppbv) with the higher mean value of 51 ppbv in spring (March to May), and large variability (14 ppbv) with the lower mean value of 32 ppbv in summer (June to September). Highest monthly mean volume concentration (2.7 μm3/cm3) of accumulation particles (0.3 μm < D < 1.0 μm) was observed in June, while the mean value in winter (October to February) was 0.7 μm3/cm3. On the basis statistics of backward air trajectory analyses, a stagnant airflow in summer over the coastal areas of the Yellow Sea and near Japan is inferred to be a suitable meteorological condition to form enhanced volume concentration of accumulation particles during transport. Associating with the seasonal changes in the dominant air trajectories, SO2 emission from Miyakejima volcano since August 2000 is also an important source of the summer enhancement of accumulation particles. Highest monthly mean volume concentration (11.2 μm3/cm3) of coarse particles (D > 1.0 μm) was found in April, which was about 10 times higher than the mean value of 1.2 μm3/cm3 from summer to winter. Variability of daily nighttime volume concentrations of the coarse particles was high (standard deviation of 13.6 μm3/cm3) in spring and low (about 2 μm3/cm3) in the rest of the year. High volume concentration with large variability of the coarse particles in spring is caused by frequent arrival of Kosa (yellow dust) particles from the Asian continent. Rapid enhancement of coarse volume concentration was often observed to increase as much as 30 times within 3 hours during Kosa phenomena. The year 2001 had particularly strong Kosa activity with a prolonged season starting early January and ending early July.
Asymmetry of ejecta flow during oblique impacts using three‐dimensional particle image velocimetry
Authors: Anderson Jennifer L. B. , Schultz Peter H. , Heineck James T.
Published: August 2003

Three‐dimensional particle image velocimetry (3D PIV) applied to impact cratering experiments allows the direct measurement of ejecta particle positions and velocities within the ejecta curtain as the crater grows. Laboratory experiments were performed at the NASA Ames Vertical Gun Range with impact velocities near 1 km/s (6.35‐mm diameter aluminum spheres) into a medium‐grained (0.5 mm) particulate sand target in a vacuum at 90° and 30° from the horizontal. This study examines the first 50% of crater growth, during which the crater has grown to one half its final radius. From the 3D PIV data, the ballistic trajectories of the ejecta particles are extrapolated back to the target surface to determine ejection velocities, angles, and positions. For vertical impacts these ejection parameters remain constant in all directions (azimuths) around the crater center. The 30° impacts exhibit asymmetries with respect to azimuth that persist well into the excavation‐stage flow. These asymmetries indicate that a single stationary point source is not adequate to describe the subsurface flow field during an oblique impact.
Intranasal immunization of humans with Streptococcus mutans antigens
Authors: Li F. , Michalek S. M. , Dasanayake A. P. , Li Y. , Kirk K. , Childers N. K.
Published: August 2003

To evaluate the effectiveness of a low dose of soluble or liposomal (L) glucosyltransferase‐enriched preparation (E‐GTF) in inducing mucosal immune responses after intranasal immunization, 12 adults were immunized on days 0 and 7 by the IN route with 62.5 μg of soluble E‐GTF or L‐E‐GTF. An increase in the mean salivary IgA anti‐E‐GTF response (P < 0.03) was seen in the L‐E‐GTF but not the soluble E‐GTF group. A significant increase (P < 0.05) in the mean specific IgA antibody activity was also seen in nasal wash from both groups. Although the nasal wash responses were higher in the L‐E‐GTF than in the soluble E‐GTF group, they were not significantly different. The soluble E‐GTF immunized group showed a higher serum IgG response than the L‐E‐GTF immunized group on day 90 (P < 0.05). These results indicate that as little as 62.5 μg of E‐GTF, when given by the intranasal route, induced an IgA response in secretions.
Oral and intestinal microflora in 5‐fluorouracil treated rats, translocation to cervical and mesenteric lymph nodes and effects of probiotic bacteria
Authors: von Bültzingslöwen I. , Adlerberth I. , Wold A. E. , Dahlén G. , Jontell M.
Published: August 2003

Serious systemic infections may occur during cancer chemotherapy due to disturbances in the oropharyngeal and gastrointestinal microflora, impaired mucosal barrier functions and immunosuppression. Bacteria may spread from the gastrointestinal tract to the regional lymph nodes. The routes for bacterial spread from the oral cavity are less well known. In the present study we investigated changes in the oral and intestinal microfloras in rats given 50 mg/kg 5‐fluorouracil (5‐FU) i.v. for 6 days. Bacterial dissemination to the lymph nodes draining the oral cavity and the lymph nodes draining the gastrointestinal tract was examined. Effects of adding the probiotic strain Lactobacillus plantarum 299v in the drinking water to the rats were measured. 5‐FU treatment caused an increase in the number of facultative and strictly anaerobic bacteria in biopsies from the oral cavity and an increase in the number of facultative anaerobes in the large intestine. The proportion of facultative gram‐negative rods increased in both the oral cavity and intestine. Bacteria translocated to both the cervical and mesenteric lymph nodes in untreated animals and increased in numbers after 5‐FU treatment due to an increase in the number of facultative gram‐negative rods. Treatment with L. plantarum 299v improved food intake and body weight in 5‐FU‐treated rats. It also reduced the 5‐FU‐induced raise in the total numbers of facultative anaerobes in the intestine, but did not reduce translocation and did not prevent diarrhea. This study reinforces the oral cavity, along with the gastrointestinal tract, as a source for bacterial dissemination. The use of probiotic bacteria may reduce some side effects of 5‐FU treatment.
Microbiological analysis of infected root canals from symptomatic and asymptomatic teeth with periapical periodontitis and the antimicrobial susceptibility of some isolated anaerobic bacteria
Authors: Jacinto R. C. , Gomes B. P. F. A. , Ferraz C. C. R. , Zaia A. A. , Filho F. J. Souza
Published: August 2003

The purpose of the present study was to investigate the correlation between the composition of the bacterial flora isolated from infected root canals of teeth with apical periodontitis with the presence of clinical signs and symptoms, and to test the antibiotic susceptibility of five anaerobic bacteria mostly commonly found in the root canals of symptomatic teeth against various substances using the E‐test. Microbial samples were taken from 48 root canals, 29 symptomatic and 19 asymptomatic, using adequate techniques. A total of 218 cultivable isolates were recovered from 48 different microbial species and 19 different genera. Root canals from symptomatic teeth harbored more obligate anaerobes and a bigger number of bacterial species than the asymptomatic teeth. More than 70% of the bacterial isolates were strict anaerobes. Statistical analysis used a Pearson Chi‐squared test or a one‐sided Fisher's Exact test as appropriate. Suggested relationships were found between specific microorganisms, especially gram‐negative anaerobes, and the presence of spontaneous or previous pain, tenderness to percussion, pain on palpation and swelling amoxicillin, amoxicillin + clavulanate and cephaclor were effective against all the strains tested. The lowest susceptibility rate was presented by Prevotella intermedia/nigrescens against Penicillin G. Our results suggested that specific bacteria are associated with endodontic symptoms of infected teeth with periapical periodontitis and the majority of the anaerobic bacterial species tested were susceptible to all antibiotics studied.
Sensitivity of genera Porphyromonas and Prevotella to the bactericidal action of C‐terminal domain of human CAP18 and its analogues
Authors: Isogai E. , Isogai H. , Matuo K. , Hirose K. , Kowashi Y. , Okumuara K. , Hirata M.
Published: August 2003

This paper reports the effect of the synthesized 27‐amino acid sequence in the C‐terminal domain of human CAP18 (hCAP18), a human cationic antibacterial protein or cathelicidin, on certain strains belonging to the genera Porophyromonas and Prevotella. The domain binds lipopolysaccharides (LPS) from Porophyromonas gingivalis and Porophyromonas circumdentaria as well as enterobacterial LPS. Two analogues of hCAP18, designated LL/CAP18 and FF/CAP18, were also tested to determine whether additional activity was obtained. The analogue peptides replaced with hydrophobic and cationic amino acid residues showed more potent bactericidal and LPS‐binding activities than the original one.
Effect of age on immunoglobulin A subclass distribution in human parotid saliva
Authors: Childers N. K. , Greenleaf C. , Li F. , Dasanayake A. P. , Powell W. D. , Michalek S. M.
Published: August 2003

Two subclasses of immunoglobulin A (IgA) antibodies are produced in humans, IgA1 and IgA2, IgA2 being more resistant to digestion by bacterial proteases than IgA1. The amount of IgA in saliva has been shown to vary with age; however, little is known about the correlation between IgA subclass distribution in saliva and age. The purpose of this study was to determine whether differences exist in the levels and ratio of IgA subclasses in parotid saliva of children and adults. Parotid saliva was obtained from healthy children (age range 6–12 years, n = 14) and adults (age range 22–51 years, n = 20) using Schaefer cups. Samples were analyzed for levels of total IgA, IgA1, and IgA2 by ELISA. IgA and IgA1 levels were significantly higher in adults than in children. However, no differences were seen in the ratio of IgA1 and IgA2 in the two groups of subjects. These findings indicate that levels of IgA increase with age, whereas the IgA subclass ratio is established early in life.
Coaggregation of Streptococcus salivarius with periodontopathogens: evidence for involvement of fimbriae in the interaction with Prevotella intermedia
Authors: Lévesque C. , Lamothe J. , Frenette M.
Published: August 2003

Streptococcus salivarius is divided into two serological subgroups that carry either fibrils or fimbriae. Although fimbriae have been observed on up to 50% of S. salivarius strains in the human oral cavity, no function has yet been assigned to them. To determine whether S. salivarius fimbriae have a role in adhesion, we examined the ability of S. salivarius to coaggregate with selected microorganisms involved in periodontal diseases. Our results show that S. salivarius coaggregated with Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia. However, only fimbriated S. salivarius cells were able to coaggregate with P. intermedia, suggesting a specific role for these structures in the interaction. Heat treatment, sensitivity to sugars, amino acids, and EDTA, as well as protease treatment were also used to further characterize coaggregation between S. salivarius and periodontopathogens.
Clonal identity of Candida albicans in the oral cavity and the gastrointestinal tract of pre‐school children
Authors: Hossain H. , Ansari F. , Schulz‐Weidner N. , Wetzel W.‐E. , Chakraborty T. , Domann E.
Published: August 2003

The clonal relationship between oral and fecal Candida albicans isolated from children of pre‐school age was examined using RAPD analysis. Significantly higher levels of C. albicans were found in saliva, dental plaque, carious specimens and stools of 56 patients with severe caries as compared to 52 healthy control subjects. The highest prevalence was found in carious specimens and a strong correlation was observed between its presence in saliva, dental plaque, carious specimen and feces. RAPD analysis of isolates from 23 patients with simultaneous oral and fecal C. albicans revealed clonal counterparts present in both oral and stool samples in 15 cases; five patients harbored closely related strains; and three patients harbored unrelated strains. Our results demonstrate a strong correlation between oral and gastrointestinal C. albicans colonization. We assume that carious teeth may constitute an ecologic niche for C. albicans potentially responsible for recurrent oral and non‐oral candidiasis.
Cloning and expression of α‐d‐glucosidase and N‐acetyl‐β‐glucosaminidase from the periodontal pathogen, Tannerella forsythensis (Bacteroides forsythus)
Authors: Hughes C. V. , Malki G. , Loo C. Y. , Tanner A. C. R. , Ganeshkumar N.
Published: August 2003

Screening a genomic library of Tannerella forsythensis (Bacteroides forsythus), using synthetic substrates conjugated to a fluorogen, 4‐methylumbelliferone identified two glycosidase genes, which encode α‐d‐glucosidase and N‐acetyl‐β‐d‐glucosaminidase, respectively. The α‐d‐glucosidase has a Mr of 81,141 and is homologous to an α‐d‐glucosidase from Bacteroidesthetaiotaomicron. The N‐acetyl‐β‐d‐glucosaminidase has a Mr of 87,787 and is homologous to an N‐acetyl‐β‐d‐glucosaminidase in Porphyromonasgingivalis W83.
Virulence factors of Porphyromonas gingivalis are modified by polyphenol oxidase and asparaginase
Authors: Budu C. E. , Luengpailin J. , Reyes G. , Doyle R. J. , Cowan M. M.
Published: August 2003

Porphyromonas gingivalis is a well‐adapted pathogen of the periodontal pocket distinguished by its wide array of proteolytic activities and its ability to adhere to multiple substrata in the oral cavity. Microbial proteins with binding functions (such as adhesins and enzymes) very often contain critical tyrosine residues, supported by one or more asparagines in the binding cleft. This study investigates the reduction in adhesiveness and in proteolytic activity after treating P. gingivalis with the tyrosine‐ and asparagine‐targeting enzymes polyphenol oxidase (PPO) and asparaginase (ASG). Cysteine protease activity was reduced by pretreatment with both enzymes, while the trypsin‐like activity was affected only by PPO. Adhesion to buccal epithelial cells, laminin and fibronectin as well as hemagglutination was reduced by one or both of the enzymes. PPO, but not ASG, reduced the coaggregation of P. gingivalis with Actinomyces naeslundii. Treatment with these enzymes might provide an alternative to traditional antimicrobial strategies.
Induction of suppressor cells following mucosal presentation of Actinomyces viscosus in mice
Authors: Sosroseno W. , Bird P. S. , Gemmell E. , Seymour G. J.
Published: August 2003

Mucosal presentation of Actinomyces viscosus results in antigen‐specific systemic immune suppression, known as oral tolerance. The aim of the present study was to determine the mechanism by which this oral tolerance is induced. DBA/2 mice were gastrically immunized with A. viscosus. Serum, Peyer's patch (PP) and spleen cells were transferred to syngeneic recipients which were then systemically challenged with the sameiA. viscosus strain. To determine antigen‐specificity of cells from gastrically immunized mice, recipients which received immune spleen cells were also challenged with Porphyromonas gingivalis. One week after the last systemic challenge, the delayed type hypersensitivity (DTH) response was determined by footpad swelling and the level of serum IgG, IgA and IgM antibodies to A. viscosus or P. gingivalis measured by an ELISA. No suppression of DTH response or of specific serum antibodies was found in recipients which received serum from gastrically immunized mice. Systemic immune suppression to A. viscosus was observed in recipients which had been transferred with PP cells obtained 2 days but not 4 and 6 days after gastric immunization with A. viscosus. Conversely, suppressed immune response could be seen in recipients transferred with spleen cells obtained 6 days after gastric immunization. The immune response to P. gingivalis remained unaltered in mice transferred with A. viscosus–gastrically immunized cells. The results of the present study suggest that oral tolerance induced by A. viscosus may be mediated by antigen‐specific suppressor cells which originate in the PP and then migrate to the spleen.
Identification of mutans streptococci by restriction fragment length polymorphism analysis of polymerase chain reaction‐amplified 16S ribosomal RNA genes
Authors: Sato T. , Hu J.P. , Ohki K. , Yamaura M. , Washio J. , Matsuyama J. , Takahashi N.
Published: August 2003

Mutans streptococci are frequently isolated from dental plaque and carious lesions. These bacteria have been identified by conventional methods such as biochemical and serologic tests followed by the isolation of colonies on the mitis‐salivarius agar, which are sometimes inconsistent. Recently, species‐specific polymerase chain reaction (PCR) has been reported to rapidly identify Streptococcus mutans and Streptococcus sobrinus. However, in the case of identification and classification into several species, e.g. within the group of mutans streptococci consisting of seven species, the identification using species‐specific PCR seems somewhat inefficient because of need for the development and preparation of specific primers for each species. Therefore, in this study we developed a simple method using restriction fragment length polymorphism analysis of PCR‐amplified 16S ribosomal RNA genes (16S rRNA genes PCR‐RFLP) for the identification of seven different species included in the group of mutans streptococci. We amplified 16S rRNA gene sequences from genomic DNA samples by PCR using universal primers and digested the PCR products with the restriction endonucleases, HpaII and HaeIII. HpaII produced six RFLP patterns for eight reference strains, since the patterns for S. sobrinus, Streptococcus downei and Streptococcus ferus were similar. RFLP patterns produced with HaeIII could separate these three species. Furthermore, the RFLP patterns predicted from the 16S rRNA gene sequences in the GenBank database agreed with the actual RFLP patterns produced in the present study. The 16S rRNA sequence comparisons can be used to identify oral mutans streptococci; however, the identification by sequencing is sometimes difficult in large‐scale studies and for small laboratories. Therefore, 16S rRNA genes PCR‐RFLP, using HpaII and HaeIII, could be an alternative method for the identification of mutans streptococci, and may be applicable for large‐scale studies on the cariogenicity of mutans streptococci.
Calorie restriction reduces pinealectomy‐induced insulin resistance by improving GLUT4 gene expression and its translocation to the plasma membrane
Authors: Zanquetta Melissa M. , Seraphim Patricia M. , Sumida Doris H. , Cipolla‐Neto Jose , Machado Ubiratan F.
Published: August 2003

Abstract: The present study aimed to investigate insulin sensitivity and GLUT4 expression protein in pinealectomized rats, as well as to determining the effects of melatonin and calorie restriction on the changes induced by pinealectomy. Wistar rats were pinealectomized (Pinx) or sham operated (Sham), and studied 30 days later. Melatonin replacement treatment (50 g/100 g body weight) was continued for 30 days after pinealectomy. Calorie restriction was performed by offering 60% of the standard food intake. In vivo insulin sensitivity was evaluated using the glucose disappearance constant (kITT) during an insulin tolerance test, and GLUT4 mRNA and protein were assessed by Northern and Western blotting, respectively. The in vitro effect of melatonin on GLUT4 protein content in plasma membrane was investigated in adipocytes isolated from intact rats. Compared with Sham rats, Pinx rats showed decreased kITT (40%), GLUT4 expression in white adipose tissue (WAT, ∼70%), and unchanged GLUT4 expression in skeletal muscle. Melatonin treatment in Pinx rats restored the kITT and GLUT4 protein to control values. No in vitro effects of melatonin (10−9 m) upon GLUT4 protein were observed. Calorie restriction of Pinx rats increased their kITT value (∼40%), total GLUT4 protein content (∼240%) and its translocation to the plasma membrane (∼80%) in WAT. The results show that pinealectomy, for lack of melatonin, decreased insulin sensitivity as well as GLUT4 gene expression. Calorie restriction improved insulin sensitivity in Pinx rats, and this was related to increased GLUT4 gene expression and insulin‐induced GLUT4 translocation to the plasma membrane in WAT.
Low melatonin secretion associates with albedo in circumpolar environments
Authors: Leppäluoto Juhani , Sikkilä Kirsti , Meyer‐Rochow Victor Benno , Hassi Juhani
Published: August 2003

Abstract: To clarify how seasonal changes of environmental luminosity affect melatonin secretion in human beings, nocturnal urine samples were collected every 2 months throughout the year from 20 outdoor workers living in an area, for which exact data on solar irradiance and temperature were available (67–68°N). Melatonin secretion rates, determined by melatonin‐specific radioimmunoassays, were found to be twice as high in December as in April, i.e. 0.88 ± 0.16 nmol/12 hr (mean ± S.E.) versus 0.43 ± 0.09 nmol/12 hr, P < 0.05. Regression analyses showed that melatonin values correlated best inversely with solar irradiance reflected off the ground (albedo). A 10‐fold increase in albedo for 1–4 weeks prior to the date of urine sampling was associated with a ca. 50% reduction in melatonin secretion. Association with global irradiance was weaker and did not correlate with temperature. Thus, light reaching the eyes via snow or other reflecting surfaces appears to be most effective. These results assist us in understanding some of the mechanisms involved in certain biological phenomena that exhibit seasonal variations as, for instance, reproduction and self‐destructive behavior.
Melatonin ameliorates oxidative organ damage induced by acute intra‐abdominal compartment syndrome in rats
Authors: Şener Göksel , Kaçmaz Ayhan , User Yilmaz , Ozkan Sirri , Tilki Metin , Yeǧen Berrak Ç.
Published: August 2003

Abstract: Acutely increased intra‐abdominal pressure (IAP) can lead to multiple organ failure. As blood flow to intra‐abdominal organs is reduced by high venous resistance, ischemia‐reperfusion (I/R) injury plays an important role in the pathogenesis of abdominal compartment syndrome (ACS) following IAP. Melatonin, a secretory product of the pineal gland, is known to have free radical scavenging and antioxidative properties in several oxidative processes. The objective of this study was to examine the potential protective properties of melatonin on the oxidative organ damage in a rat model of ACS. Under ketamine anesthesia, an arterial catheter was inserted intraperioneally (i.p.) and using an aneroid manometer connected to the catheter, IAP was kept at 20 mmHg (ischemia group; I) for 1 hr. In the ischemia/reperfusion (I/R) group, pressure applied for an hour was decompressed and a 1‐hr reperfusion period was allowed. In another IR group, melatonin was administered (10 mg/kg, i.p.) immediately before the decompression of IAP. The results demonstrate that tissue levels of malondialdehyde (MDA) and myeloperoxidase activity (MPO; index of tissue neutrophil infiltration) were elevated, while glutathione (GSH; a key to antioxidant) levels were reduced in both I and I/R groups (P < 0.05–0.001). Melatonin treatment in I/R rats reversed these changes (P < 0.01–0.001). Moreover, melatonin given to the I/R group reduced the elevations in serum aspartate aminotransferase, alanine aminotransferase and blood urea nitrogen levels and abolished the increase in serum creatinine levels. Our results indicate that melatonin, because of antioxidant and free radical scavenging properties, ameliorates reperfusion‐induced oxidative organ damage. In conclusion, the results of the present study suggest that the therapeutic value of melatonin as a ‘reperfusion injury‐limiting’ agent must be considered in ACS.
Human circadian melatonin rhythm phase delay during a fixed sleep–wake schedule interspersed with nights of sleep deprivation
Authors: Cajochen Christian , Jewett Megan E. , Dijk Derk‐Jan
Published: August 2003

Abstract:  The human circadian pacemaker, with an intrinsic period between 23.9 and 24.5 hr, can be reset by low levels of light. Biomathematical models of the human clock predict that light–dark cycles consisting of only ∼3.5 lux during 16 hr of wakefulness and 0 lux during 8 hr of sleep should entrain ∼45% of the population. However, under real‐life conditions, sleep–wake schedules and the associated light–dark exposures are often irregular. It remains unclear whether the phase of the pacemaker would remain stable under such conditions. We investigated the stability of the circadian phase in dim light by assessing the plasma melatonin rhythm during nine consecutive circadian cycles. Ten subjects were scheduled to sleep for 8 hr (0.03 lux) and to be awake for 16 hr (5–13 lux) during all days except on days 4 and 8, during which the subjects were sleep deprived for 40 hr (5–13 lux), either in a sitting/standing or supine body posture. In all subjects, the phase of the melatonin rhythm occurred at a later clock time on day 9 than on day 2 (average delay: 1.4 hr). Largest delays in the melatonin onset were observed in subjects with low amplitude melatonin rhythms. The area under the curve during active melatonin secretion was significantly reduced when subjects were sleep deprived in the 40‐hr supine body posture condition compared with either the 40‐hr sitting/standing sleep deprivation (SD) or the ambulatory condition under non‐SD conditions. Posture differences did not significantly affect the relative phase position of the melatonin profiles. The data indicate that under conditions of reduced zeitgeber strength, the phase of the human circadian pacemaker, using plasma melatonin as a marker, can be phase delayed by one night of SD and the associated dim light exposure.
Effects of D1‐ and D2‐dopamine receptor activation on melatonin synthesis in bovine pinealocytes
Authors: Santanavanich Chorthip , Chetsawang Banthit , Ebadi Manuchair , Govitrapong Piyarat
Published: August 2003

Abstract: Previous studies have identified and characterized D1‐ and D2‐dopamine receptors in bovine pineal glands. The data indicate that the density of D1‐dopamine receptors (974 fmol/mg protein) far exceed that of D2‐dopamine receptors (37 fmol/mg protein). The objective of this study was to identify the mRNAs for both D1‐ and D2‐dopamine receptors and to elucidate the status of dopamine and its possible involvement in the pineal function, particularly on melatonin synthesis. The expression of these dopamine receptor subtypes were determined by using a reverse transcriptase‐polymerase chain reaction technique with specific pairs of primers to amplify D1‐ and D2‐dopamine receptor mRNAs. Amplification of RNAs from bovine striatum (positive control) and bovine pineal gland resulted in products of the predicted lengths of 231 bp for D1‐ and 333 bp for D2‐dopamine receptors. The results indicate that both D1‐ and D2‐dopamine receptor mRNAs are present in the bovine pineal gland. The role of dopamine receptors was investigated by studying the effects of selective D1‐ and D2‐dopamine agonists and antagonists on the N‐acetyltransferase (NAT) activity of cultured bovine pinealocytes. The data showed that SKF‐38393, a selective D1‐agonist, enhanced NAT activity, and increased melatonin level, and the stimulatory effect was blocked by SCH‐23390, a D1‐selective antagonist, whereas quinpirole, a selective D2‐agonist, inhibited NAT basal activity and decreased the melatonin basal level. Furthermore the inhibitory effect was blocked by D2‐selective antagonists, spiperone, haloperidol, and domperidone. The present results indicate that the pineal dopamine receptors have a distinct effect on pineal function. The precise mechanism whereby activation of dopamine receptors altered the NAT activity and melatonin level needs to be further delineated.
Melatonin slowed the early biochemical progression of hormone‐refractory prostate cancer in a patient whose prostate tumor tissue expressed MT1 receptor subtype
Authors: Shiu Stephen Y. W. , Law In C. , Lau Kai W. , Tam Po C. , Yip Andrew W. C. , Ng Wai T.
Published: August 2003

Abstract: Melatonin inhibited the proliferation of hormone‐independent LNCaP prostate cancer cells partly via MT1 receptor activation both in vitro and in nude mice xenograft model. In this study, the melatonin receptor expression in the prostate cancer tissue of a patient with bone metastases and the effect of melatonin on the biochemical progression of hormone‐refractory prostate tumor which later developed in the same patient were reported. Saturation and competition 2‐[125I]iodomelatonin binding assays were conducted on prostate tumor tissue obtained by transurethral resection of the prostate from the index patient. The receptor subtype identity of melatonin receptor expressed in the cancer tissue was determined by comparison of the rank order of inhibition constants (Ki) of various melatonergic ligands and the affinity of 4‐phenyl‐2‐propionamidotetraline relative to melatonin in inhibiting 2‐[125I]iodomelatonin binding to the tumor sample and to human cell lines stably transfected with MT1 or MT2 melatonin receptor subtype. MT1 receptor expression in the cancer tissue was also examined by immunohistochemistry. The surgically castrated patient later developed biochemical relapse of his disease. His serum total prostate‐specific antigen (PSA) level was monitored before and during treatment with 5 mg/day oral melatonin at 20:00 hr. High‐affinity (Kd = 103.7 pm) MT1 melatonin receptor subtype was expressed by the patient's prostate cancer. As indicated by his PSA levels, melatonin induced stabilization of his hormone‐refractory disease for 6 wk. This report validates melatonin's oncostatic action on prostate cancer and the potential involvement of MT1 receptor subtype in the attendant antiproliferative signal transduction as suggested by recent preclinical laboratory findings in a human.
Quantitative differences in the pineal ultrastructure of perinatal and adult harp (Phoca groenlandica) and hooded seals (Cystophora cristata)
Authors: Aarseth Jo Jorem , Stokkan Karl‐Arne
Published: August 2003

Abstract: Seals are unique among mammals in that newborns have a large pineal gland and extremely high plasma levels of melatonin at birth. Melatonin levels are also high in the seal fetus but decline rapidly during the first few days of life. The aim of the present study was to provide quantitative information about the ultrastructure of the seal pineal gland using fetal, newborn, and adult hooded seals (Cystophora cristata), and newborn and adult harp seals (Phoca groenlandica). The relative and absolute volumes of pinealocytes (Pi), arteries and veins, nerves, connective tissue, capillaries and glial cells, as well as mitocondria and lipid droplets in Pi, were calculated by use of point count analysis. Whereas the pineal ultrastructure was similar in fetuses and newborns, both seal species showed a pronounced and particular reduction in the volume of Pi and a similar reduction in pinealocyte mitochondria. There was also a shift from unmyelinated to myelinated pineal nerves in adults compared with fetal/newborns. The selective and marked reduction of Pi may explain the zonated pineal structure typical of the adult seal. The results demonstrate that the fetal gland is as large and active as that of the newborn seal and support the notion that the large size and high activity of the pineal gland in the newborn seal is a fading consequence of its prenatal condition.
Melatonin inhibits telomerase activity in the MCF‐7 tumor cell line both in vivo and in vitro
Authors: Leon‐Blanco Mercedes M. , Guerrero Juan M. , Reiter Russel J. , Calvo Juan R. , Pozo David
Published: August 2003

Abstract: In this study for the first time the relationship between melatonin and telomerase activity was investigated. Melatonin exhibits oncostatic properties, but the actual mechanism of action by which the indole reduces tumor cell activity is not clear. Telomerase is an enzyme responsible of telomere elongation and is activated in most human cancers. In the current in vivo study, eight nude mice received a MCF‐7 xenograft and thereafter they were treated for 5 weeks with 0.1 mg/mL of melatonin in the drinking water. Melatonin treatment caused a significant reduction in the weight of tumors and reduced metastases when compared with the control group. As indicated by the Telomerase Repeats Amplification Protocol (TRAP) assay, a significant decrease in telomerase activity was observed in the group treated with melatonin. In related in vitro studies, cultured MCF‐7 cells were treated with three different concentrations of melatonin and a control without indole treatment. A significant dose‐dependent decrease in Telomerase reverse transcriptase (TERT), the catalytic subunit of telomerase, mRNA expression was observed in the melatonin‐treated cells. We also observed a significant reduction in TR, the RNA telomerase subunit, mRNA expression at physiological concentrations of melatonin (1 nm). Significant differences in TEP1, an associated telomerase protein, mRNA expression were also observed. In conclusion, melatonin influences telomerase both in vivo and in vitro, decreasing its activity in the tumors of nude mice and the mRNA expression of the TERT and TR subunits, essential factors for the proper function of the telomerase enzyme.