bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Humoral Immunity to Commensal Oral Bacteria in Human Infants Demonstrates the Presence of Secretory Immunoglobulin A Antibodies Reactive with
Actinomyces naeslundii
Genospecies 1 and 2 Ribotypes
Authors: Cole Michael F. , Evans Mishell K. , Kirchherr Jennifer L. , Sheridan Michael J. , Bowden G. H. W.
Published: May 2004

The mouths of three human infants were examined from birth to age 2 years to detect colonization of
Actinomyces naeslundii
genospecies 1 and 2. These bacteria did not colonize until after tooth eruption. The diversity of posteruption isolates was determined by ribotyping. Using immunoblotting and enzyme-linked immunosorbent assay, we determined the reactivity of secretory immunoglobulin A (SIgA) antibodies in saliva samples collected from each infant before and after colonization against cell wall proteins from their own
A. naeslundii
strains and carbohydrates from standard
A. naeslundii
genospecies 1 and 2 strains.
A. naeslundii
genospecies 1 and 2 carbohydrate-reactive SIgA antibodies were not detected in any saliva sample. However, SIgA antibodies reactive with cell wall proteins were present in saliva before these bacteria colonized the mouth. These antibodies could be almost completely removed by absorption with
A. odontolyticus
, a species known to colonize the human mouth shortly after birth. However, after colonization by
A. naeslundii
genospecies 1 and 2, specific antibodies were induced that could not be removed by absorption with
A. odontolyticus
. Cluster analysis of the patterns of reactivity of postcolonization salivary antibodies from each infant with antigens from their own strains showed that not only could these antibodies discriminate among strains but antibodies in saliva samples collected at different times showed different reactivity patterns. Overall, these data suggest that, although much of the salivary SIgA antibodies reactive with
A. naeslundii
genospecies 1 and 2 are directed against genus-specific or more broadly cross-reactive antigens, species, genospecies, and possibly strain-specific antibodies are induced in response to colonization.
Toll-Like Receptor 4 Mediates the Antitumor Host Response Induced by a 55-Kilodalton Protein Isolated fromAeginetia indicaL., a Parasitic Plant
Authors: Okamoto Masato , Oh-e Go , Oshikawa Tetsuya , Furuichi Sachiko , Tano Tomoyuki , Ahmed Sharif U. , Akashi Sachiko , Miyake Kensuke , Takeuchi Osamu , Akira Shizuo , Himeno Kunisuke , Sato Mitsunobu , Ohkubo Shinya
Published: May 2004

A 55-kDa protein named AILb-A, isolated from the seed extract ofAeginetia indicaL., a parasitic plant, induces a Th1-type T-cell response and elicits a marked antitumor effect in tumor-bearing mice. In the present study, we examined the role of Toll-like receptors (TLRs), which have been implicated in pathogen-induced cell signaling, in AILb-A-induced immune responses. In the luciferase assay using a nuclear factor (NF)-κB-dependent reporter plasmid, AILb-A induced NF-κB activation in the cells transfected with TLR4, but not with those transfected with the TLR2 gene, in a dose-dependent manner. TLR4-mediated NF-κB activation induced by AILb-A but not by lipopolysaccharide (LPS) was also observed under serum-free conditions. In in vitro experiments using human peripheral blood mononuclear cells, AILb-A-induced cytokine production was markedly inhibited by anti-TLR4 but not by anti-CD14 antibody, while LPS-induced, TLR4-mediated cytokine production was inhibited by anti-CD14 as well as anti-TLR4 antibodies. Cytokine production, killer cell activities, maturation of dendritic cells, phosphorylation of mitogen-activated protein kinases, and nuclear translocation of interferon-regulatory factor 3 induced by AILb-A were severely impaired in TLR4-deficient but not TLR2-deficient mice. Transfection of TLR4-deficient mouse-derived macrophages with the TLR4 expression plasmid led AILb-A to induce cytokines. Finally, the antitumor effect of AILb-A was also impaired in TLR4-deficient and TLR4-mutated mice. These findings suggest that TLR4 mediates antitumor immunity induced by the plant-derived protein AILb-A.
Vaccination with Recombinant Whole Heavy Chain Fragments of
Clostridium botulinum
Type C and D Neurotoxins
Authors: Arimitsu Hideyuki , Lee Jae-Chul , Sakaguchi Yoshihiko , Hayakawa Yuji , Hayashi Michiko , Nakaura Miki , Takai Hikaru , Lin Song-Nan , Mukamoto Masafumi , Murphy Tom , Oguma Keiji
Published: May 2004

Mice and ducks were subcutaneously immunized with recombinant whole heavy (H) chains of
Clostridium botulinum
type C and D neurotoxins, which were expressed as glutathione
S
-transferase fusion proteins. In the case of mice, it was confirmed that two immunizations with type C- and D-H chains, 10 μg each time, significantly increased the specific antibodies against 100-kDa H chains of type C and D neurotoxins in an immunoblot analysis and an enzyme-linked immunosorbent assay, respectively. The mice immunized with type C- and D-H chains showed no symptoms of botulism when they were challenged with C- and D-16 S toxins at doses, given intraperitoneally, of up to 10
5
and 10
6
minmum lethal doses (MLD), respectively, per mouse. Ducks were immunized with a total of 100 μg of type C-H chain. The ducks also developed specific antibodies to the type C-H chain and showed significant protection against a challenge with 10
3
duck MLD of C-16 S toxin given intravenously. These results indicate that recombinant whole H chains can be used as an effective and safe vaccine for type C and D botulism in domestic animals.
2F3 Monoclonal Antibody Recognizes the O26 O-Antigen Moiety of the Lipopolysaccharide of EnterohemorrhagicEscherichia coliStrain 4276
Authors: Szalo I. M. , Taminiau B. , Goffaux F. , Pirson V. , McCappin J. , Ball H. J. , Mainil J. G.
Published: May 2004

EnterohemorrhagicEscherichia coli(EHEC) and enteropathogenicE. coli(EPEC) organisms are groups of pathogenic strains whose infections are characterized by a typical lesion of enterocyte attachment and effacement. They are involved in enteric diseases both in humans and in animals, and EHEC strains can be responsible for hemolytic uremic syndrome in humans. Previously, it was shown that the 2F3 monoclonal antibody (MAb) is specific for the O26 EHEC and EPEC strains (P. Kerr, H. Ball, B. China, J. Mainil, D. Finlay, D. Pollock, I. Wilson, and D. Mackie, Clin. Diagn. Lab. Immunol.6:610-614, 1999). As these groups of bacteria play an important role in pathology, the aim of this paper was to characterize the antigen recognized by the 2F3 MAb and its genetic determinant. A genomic locus containing the entire O-antigen gene cluster and half of the colanic acid gene cluster from an O26 EHEC strain was shown to be sufficient for the production of the antigen recognized by the 2F3 MAb in anE. coliDH5α strain. By transposon mutagenesis performed on the recombinant plasmid, all 2F3 enzyme-linked immunosorbent assay-negative mutants had their transposons inserted into the O-antigen gene cluster. The O-antigen gene cluster was also cloned from an O26 EHEC strain into theE. coliDH5α strain, which then produced a positive result with the 2F3 MAb. Further analysis of the type of lipopolysaccharides (smooth or rough) produced by the clones and mutants and of the O antigen of the 2F3-positive clones confirmed that the epitope recognized by the 2F3 MAb is located on the O antigen in the O26 EHEC and EPEC strains and that its genetic determinant is located inside the O-antigen gene cluster.
Interleukin-8 Response in an Intestinal HCT-8 Cell Line Infected with Enteroaggregative and Enterotoxigenic
Escherichia coli
Authors: Huang David B. , DuPont Herbert L. , Jiang Zhi-Dong , Carlin Lily , Okhuysen Pablo C.
Published: May 2004

This study examined the interleukin-8 (IL-8) response of the intestinal adenocarcinoma HCT-8 cell line to infection with enteroaggregative and enterotoxigenic
Escherichia coli
pathotypes isolated from patients with travelers' diarrhea. Individual diarrheagenic
E. coli
strains (enteroaggregative
E. coli
[EAEC];
n
= 30), heat-stable enterotoxin (ST)-producing enterotoxigenic
E. coli
(ETEC ST;
n
= 11), heat-labile enterotoxin (LT)-producing enterotoxigenic
E. coli
(ETEC LT;
n
= 10), and ST- and LT-producing enterotoxigenic
E. coli
(ETEC ST:LT;
n
= 8) were coincubated with HCT-8 cells for 3 h. Tissue culture supernatants were assayed for IL-8 content by enzyme-linked immunosorbent assay. Fifty percent of EAEC (72% of those EAEC carrying the virulence factors
aggR
,
aggA
, and
aspU
and 40% of those EAEC not carrying virulence factors) and 64% of ETEC ST elicited IL-8 production. In contrast, 10% of ETEC LT elicited the production of IL-8 above baseline. These results suggest that (i) the HCT-8 cell line infection model can be used as a tool to differentiate proinflammatory
E. coli
from noninflammatory isolates; (ii) EAEC has a heterogeneous ability to induce the production of IL-8, and this may be associated with the presence of virulence factors; and (iii) ETEC ST can elicit an inflammatory response and helps explain our earlier findings of increased fecal IL-8 in patients with ETEC diarrhea.
Use of a Synthetic Peptide Epitope of Asp f 1, a Major Allergen or Antigen ofAspergillus fumigatus, for Improved Immunodiagnosis of Allergic Bronchopulmonary Aspergillosis
Authors: Madan Taruna , Priyadarsiny Priyanka , Vaid Mudit , Kamal Neel , Shah Ashok , Haq Wahajul , Katti Seturam Bandacharya , Sarma P. Usha
Published: May 2004

Allergic bronchopulmonary aspergillosis (ABPA) is an immunologically complex allergic disorder caused by the fungal pathogenAspergillus fumigatus. Elevated levels of total immunoglobulin E (IgE), specific IgE, and IgG antibodies in sera are important immunodiagnostic criteria for ABPA. International reference standards or standardized immunodiagnostic assays are not available due to a lack of well-defined diagnostic antigens. The present study was carried out to identify and evaluate the immunodiagnostic relevance of synthetic epitopic peptides of Asp f 1, a major allergen, antigen, or cytotoxin ofA. fumigatus. Five overlapping peptides were synthesized from the N terminus of Asp f 1, one of the potential immunodominant regions predicted by algorithmic programs. The 11-amino-acid synthetic peptide (P1) significantly inhibited both IgG binding (89.10% ± 4.45%) and IgE binding (77.32% ± 3.38%) of the standardized diagnostic antigen (SDA) (a well-defined pool of diagnostically relevant allergens and antigens ofA. fumigatus). With a panel of sera of ABPA patients, allergic patients with skin test negativity toA. fumigatus, and healthy individuals, P1 showed a higher diagnostic efficiency than SDA (specific IgG, 100%; specific IgE, 98.3%). The diagnostic efficiency of P1 could be attributed to the presence of homologous epitopes in various immunodominant allergens or antigens ofA. fumigatus. The ability of P1 to induce histamine release from sensitized mast cells and a Th2 type of cytokine profile in peripheral blood mononuclear cells of ABPA patients suggests its potential for use in intradermal testing. P1 could be further explored for development of a standardized, specific, and sensitive immunodiagnostic test for aspergillosis.
Immunosuppressive and Anti-Inflammatory Effects of Nicotine Administered by Patch in an Animal Model
Authors: Kalra Roma , Singh Shashi P. , Pena-Philippides Juan C. , Langley Raymond J. , Razani-Boroujerdi Seddigheh , Sopori Mohan L.
Published: May 2004

To study the immunological effects of nicotine, there are several rodent models for chronic nicotine administration. These models include subcutaneously implanted miniosmotic pumps, nicotine-spiked drinking water, and self-administration via jugular cannulae. Administration of nicotine via these routes affects the immune system. Smokers frequently use nicotine patches to quit smoking, and the immunological effects of nicotine patches are largely unknown. To determine whether the nicotine patch affects the immune system, nicotine patches were affixed daily onto the backs of Lewis rats for 3 to 4 weeks. The patches efficiently raised the levels of nicotine and cotinine in serum and strongly inhibited the antibody-forming cell response of spleen cells to sheep red blood cells. The nicotine patch also suppressed the concanavalin A-induced T-cell proliferation and mobilization of intracellular Ca2+by spleen cells, as well as the fever response of animals to subcutaneous administration of turpentine. Moreover, immunosuppression was associated with chronic activation of protein tyrosine kinase and phospholipase C-γ1 activities. Thus, in this animal model of nicotine administration, the nicotine patch efficiently raises the levels of nicotine and cotinine in serum and impairs both the immune and inflammatory responses.
Effects of Feeding a Probiotic Preparation (SIM) Containing Inulin on the Severity of Colitis and on the Composition of the Intestinal Microflora in HLA-B27 Transgenic Rats
Authors: Schultz M. , Munro K. , Tannock G. W. , Melchner I. , Göttl C. , Schwietz H. , Schölmerich J. , Rath H. C.
Published: May 2004

An overly aggressive immune response to the intestinal microflora in a genetically susceptible host background has been implicated in the pathogenesis of inflammatory bowel diseases. We measured the impact of a probiotic preparation (SIM) containing inulin on the severity of colitis and on intestinal microflora profiles of HLA-B27-β
2
-microglobulin transgenic (TG) rats. SIM is a mixture of lactobacilli, bifidobacteria, and inulin. Two-month-old TG rats received either SIM or water. Control TG rats received metronidazole, alone or in combination with SIM, for 8 weeks. Nontransgenic rats received SIM or water. The cecal content was removed for analysis of the intestinal microflora by PCR combined with denaturing gradient gel electrophoresis. The colon was scored for histological evidence of inflammation, colonic myeloperoxidase activity and interleukin-1β RNA levels were measured photometrically or by real-time quantitative PCR. At 4 months, the colonic inflammation of TG rats treated with SIM was histologically diminished compared to that in untreated TG rats (2.2 ± 0.2 versus 2.9 ± 0.1;
P
≤ 0.03). The administration of SIM altered the microflora profiles of TG rats by increasing the diversity and stimulating specifically the growth of
Bifidobacterium animalis
. The probiotic bacteria added to SIM were below the detection level in cecal stool samples at the end of the study period. The administration of SIM resulted in a measurable impact on the cecal microflora profiles of TG rats with attenuation of colitis. The lack of detection of any added probiotic bacteria in the cecal content suggests that prebiotic inulin is the major effective compound.
Transgenic Mice Showing Inflammation-Inducible Overexpression of Granulocyte Macrophage Colony-Stimulating Factor
Authors: Burke B. , Pridmore A. , Harraghy N. , Collick A. , Brown J. , Mitchell T.
Published: May 2004

We used the promoter of the human C-reactive protein (CRP) gene to drive inflammation-inducible overexpression of the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) in transgenic mice. Transgenic mice carrying a CRP/GM-CSF fusion gene show a >150-fold increases in circulating levels of GM-CSF within 6 h of intraperitoneal inoculation with 25 μg of lipopolysaccharide. However, some of the transgenic mice also display relatively high basal levels of GM-CSF in the absence of any obvious inflammatory stimulus. Raised basal levels of GM-CSF are associated with a number of pathological changes, including enlarged and histologically abnormal livers and spleens and with increases in the number and activation state of macrophages and granulocytes in the peripheral blood. Despite problems associated with the expression of such a potent pleiotropic cytokine as GM-CSF, the principle of inflammation-inducible expression of chimeric constructs has been shown to be feasible. Inducible expression systems such as that described here could be of potential use in the study of the role of cytokines in health and disease and in the development of disease-resistant strains of livestock.
Interlaboratory Reliability of Microimmunofluorescence Test for Measurement ofChlamydia pneumoniae-Specific Immunoglobulin A and G Antibody Titers
Authors: Littman Alyson J. , Jackson Lisa A. , White Emily , Thornquist Mark D. , Gaydos Charlotte A. , Vaughan Thomas L.
Published: May 2004

To evaluate the reliability ofChlamydia pneumoniae-specific immunoglobulin G (IgG) and IgA antibody titers as measured by the microimmunofluorescence (MIF) test, we compared results from 392 individuals using a standard MIF protocol at two academic laboratories. The kappas for dichotomous titers (≥16 versus <16) were 0.39 for IgA and 0.53 for IgG. Measurement error likely attenuatesC. pneumoniae-disease associations; the magnitude of attenuation can be estimated from results of studies such as this one.
Evaluation of Commercial Immunoassays for Detection of Antibody against
Helicobacter pylori
in Thai Dyspeptic Patients
Authors: Hanvivatvong Orrawadee , Pongpanich Atinop , Thong-Ngam Duangporn , Thammacharoenrach Niramol , Kullavanijaya Pinit
Published: May 2004

The performance of five immunoassays for detection of immunoglobulin G antibody against
Helicobacter pylori
in 191 dyspeptic patients was evaluated. The sensitivities, specificities, accuracies, positive predictive values, and negative predictive values ranged from 86.32 to 97.89%, 57.95 to 72.22%, 77.02 to 83.76%, 71.54 to 77.42%, and 83.33 to 96.23%, respectively. The immunoglobulin A test kit also gave a high sensitivity and negative predictive value (95.79 and 91.40%, respectively), while the specificity was relatively low (51.14%).
Gender-Related Cytokine Patterns in Sera of Schistosomiasis Patients with Symmers' Fibrosis
Authors: Silva-Teixeira David Nascimento , Contigli Cristiane , Lambertucci José Roberto , Serufo José Carlos , Rodrigues Virmondes
Published: May 2004

Cytokine levels were compared between schistosomiasis patients affected by intense fibrosis defined by ultrasound examination and graded from F-0 to F-3. The concentrations of interleukin-1β (IL-1β), IL-4, IL-5, IL-10, IL-13, gamma interferon, and tumor necrosis factor alpha (TNF-α) were determined by enzyme-linked immunosorbent assay of serum samples. Levels of IL-4, IL-5, and TNF-α in the sera of F-3 patients were significantly higher than those found in F-0 individuals, while levels of IL-13 were lower. Levels of IL-4, IL-5, and TNF-α in serum were significantly higher in F-3 males than in F-0 males or F-3 females. Conversely, levels of IL-13 were significantly lower in F-3 females than in F-0 females and males.
Hyperglycaemic crises and lactic acidosis in diabetes mellitus
Authors: English P , Williams G
Published: May 2004

Diabetic ketoacidosis, hyperglycaemic hyperosmolar state, and lactic acidosis represent three of the most serious acute complications of diabetes. There have been some advances in our understanding of the pathogenesis of these conditions over the last three decades, together with more uniform agreement on their treatment and innovations in technology. Accordingly their incidence, morbidity, and mortality are decreasing, but at rates that fall short of our aspirations. Hyperglycaemic crises in particular remain an important cause of morbidity and mortality in diabetic populations around the world. In this article, understanding of these conditions and advances in their management, and the available guidelines for their treatment, are reviewed. As far as is possible, the recommendations are based on clear published evidence; failing that, what is considered to be a common sense synthesis of consensus guidelines and recommendations is provided.
Tropical pyomyositis (myositis tropicans): current perspective
Authors: Chauhan S , Jain S , Varma S , Chauhan S S
Published: May 2004

Tropical pyomyositis, a disease often seen in tropical countries, is characterised by suppuration within skeletal muscles, manifesting as single or multiple abscesses. The most common organism implicated is Staphylococcus aureus. In 20%–50% of cases there is a history of trauma to the affected muscles. Commonly involved muscles are quadriceps, glutei, pectoralis major, serratus anterior, biceps, iliopsoas, gastrocnemius, abdominal and spinal muscles. Early diagnosis is often missed because of lack of specific signs, unfamiliarity with the disease, atypical manifestations, and a wide range of differential diagnosis. Diagnostic techniques like ultrasound and computed tomography/magnetic resonance imaging are very useful in diagnosis. The diagnosis is confirmed either by biopsy or aspiration of pus from the affected muscles. The initial antibiotic of choice is cloxacillin. Incision and drainage are important components of management. Treatment for Gram negative or anaerobic organisms should be instituted, whenever indicated. Physicians should become more familiar with this potentially life threatening but curable infective disease entity.
Barriers to physical activity in patients with diabetes
Authors: Thomas N , Alder E , Leese G P
Published: May 2004

Purpose

Two questions were addressed: (1) How much physical activity do patients with diabetes perform? (2) What are the perceived factors that prevent patients from doing more physical activity?

Research design and methods

Interview based questionnaires were distributed to consecutive patients attending the Diabetes Clinic, Ninewells Hospital, Dundee over a period of five months. Exclusion criteria were age below 20 years and inadequate understanding of English; 428 questionnaires were given out with 406 completed.

Results

Physical activity was undertaken by 34% of patients with diabetes and only 9% of these patients exercised sufficiently to achieve a large change in heart rate or breathing. The main reasons for inactivity included perceived difficulty taking part in exercise, feelings of tiredness, and being distracted by something good on television. Lack of time and lack of local facilities also contributed.

Conclusions

Few patients with diabetes participate in physical activity, and in those who do the level of intensity is low. There are many modifiable factors distracting patients from exercise.
Use of diuretics in cardiovascular disease: (2) hypertension
Authors: Shah S U , Anjum S , Littler W A
Published: May 2004

Hypertension is a common condition associated with increased mortality and multiple morbidities. Evidence based management of hypertension is known to improve both the short term and the long term outcomes in patients with this condition. There are several general measures and pharmacological agents that are known to treat hypertension adequately. Diuretics, in particular low dose thiazide and thiazide-like diuretics, are widely used in the treatment of hypertension. They have excellent outcome data and high safety and low side effects profiles. In this article, the physiology, pharmacological actions, side effects, and outcome data of the use of diuretics in hypertension are reviewed. In addition, the effective use of diuretics in the management of hypertension is discussed.
Acute ischaemic colitis due to hypotension and amoxicillin allergy
Authors: Pérez-Carral C , Carreira J , Vidal C
Published: May 2004

A case of acute ischaemic colitis, confirmed by colonoscopy and colon biopsy, caused by IgE mediated allergy to amoxicillin is presented. The damage to the gut seemed to occur as a result of the hypotension suffered during the anaphylactic episode.
Massive pleural effusion and marked increase of CA-125
Authors: Hussain S F , Grayez J , Grigorian A , Green J T
Published: May 2004

The tumour associated CA-125 antigen is widely used in monitoring ovarian carcinoma. In women with a massive pleural effusion and ascites, markedly increased CA-125 levels may lead to an erroneous diagnosis of ovarian cancer. Very high levels of tumour markers may be present in patients with benign pleural effusion, ascites, and chronic liver disease. Raised levels of tumour markers in serum or pleural fluid, in the absence of positive cytology, should be interpreted with caution.
Professional-patient relationships and informed consent
Authors: Messer N G
Published: May 2004

Four theoretical ethical perspectives on professional-patient relationships—autonomy, justice, virtue ethics, and the ethic of care—are surveyed, and some of their implications for the informed consent requirement in health care are sketched out. The practical issues of competence to consent, adequate information, and voluntariness are reviewed, and examples are given of the ways in which the theoretical perspectives outlined earlier might inform practice in areas such as these. Finally, the situation of patients not competent to consent is considered in the light of the same theoretical perspectives.
Idiopathic perianal pruritus: washing compared with topical corticosteroids
Authors: Öztaş M O , Öztaş P , Önder M
Published: May 2004

Background

Idiopathic perianal pruritus is a poorly managed condition. Topical corticosteroids are effective in idiopathic perianal pruritus, but they may cause some side effects. In this study, the effectiveness of topical steroids were compared with perianal cleansers in the treatment of idiopathic perianal pruritus.

Patients and methods

Seventy two patients with the complaint of perianal pruritus were evaluated; 60 of the 72 patients were found to be idiopathic. Twenty eight patients were treated with topical steroids and 32 patients were treated only with a liquid cleanser.

Results

At the end of this two week period, cleansers were found to be as effective as topical corticosteroids.

Conclusion

This study shows that perianal cleansers can be used as a safe first step treatment in idiopathic perianal pruritus.
Diagnosis of tuberculous aetiology in pericardial effusions
Authors: Cherian G
Published: May 2004

The diagnosis of tuberculous aetiology in pericardial effusions is important since the prognosis is excellent with specific treatment. The clinical features may not be distinctive and the diagnosis could be missed particularly with tamponade. With the spread of HIV infection the incidence has increased. The diagnosis largely depends on histopathology of the pericardial tissue or culture of Mycobacterium tuberculosis from this tissue or fluid, but patients without haemodynamic compromise do not require pericardiocentesis. Histopathology may, however, show non-specific findings in a significant number. This review is an update on the diagnostic difficulties, current research, and criteria for diagnosis.
DIMER ORDER–DISORDER TRANSITION DEPENDENCE ON THE OPTICAL ABSORPTION PARAMETERS OF THE KHCO3 COMPOUND
Authors: ABOUELHASSAN S. , SALMAN F. , SHEHA E. , EL-MANSY M. K.
Published: May 2004

KHCO 3 compounds have been grown by the slow evaporation technique of an aqueous solution. The absorption process at the absorption edge of the compounds in the temperature range around the phase transition temperature (TF≈322 K ) was investigated. The sample exhibited exponential behavior of the absorption edge following Urbach's rule. The Urbach parameters were determined and their temperature dependence was investigated, where drastic variations of these parameters at TF were detected. The steepness parameter (s), the optical gap (Eg) and the disorder parameter (B) illustrate anomalous behavior with temperature. This behavior has been discussed in the light of the concept of order–disorder transition.
CHARACTERIZATION OF SILICON OXIDE NANOWIRES DIRECTLY GROWN FROM NiO/Si
Authors: PARK BYOUNGTAE , YONG KIJUNG
Published: May 2004

Amorphous silicon oxide nanowires ( a-SiONW's ) were synthesized on a NiO -catalyzed silicon substrate through a simple thermal annealing at 1000–1100°C without any additional silicon source materials. The synthesized nanowires were highly pure (no metal catalyst contamination) and very long (hundreds of micrometers). Most nanowires had a diameter in the range of 50–100 nm. The nickel oxide nanoparticles play a peculiar role in the synthesis of a-SiONW's . The growth of a-SiONW's is most likely controlled by the solid–liquid–solid (SLS) mechanism. IR absorption characteristics clearly showed bending (796 cm-1) and asymmetric stretching (1075 cm-1) modes of Si – O – Si bonds in a-SiONW's . An extraordinary UV emission at 370 nm was observed from a-SiONW's , which could be attributed to defect centers of oxygen excess in the nanowires.
EFFECT OF GRAIN SIZE ON THE ELECTRON WORK FUNCTION OFCuANDAl
Authors: LI WEN , LI D. Y.
Published: May 2004

The Kelvin probe is a sophisticated instrument which is very sensitive to changes in surface conditions, such as deformation, texture, phase transformation and contamination. Efforts have been made to use this technique to diagnose wear. In this study, the effect of the grain boundary (GB) on the electron work function (EWF) was examined with the aim of investigating the contribution of changes in grain size to total changes in the EWF during wear. Copper and aluminum were studied as examples. It was demonstrated that the EWF dropped in the vicinity of GB's and the mean EWF decreased as the grain size decreased. The mechanism responsible for the changes in the EWF with respect to the GB is discussed.
MONTE CARLO SIMULATION OF TEMPERATURE-PROGRAMMED DESORPTION CO/Cu(110) AND CO2/Cu(100) SYSTEMS
Authors: ZAKERI KH. , DASHTI A.
Published: May 2004

In this investigation, we have studied the kinetics and mechanism of desorption of CO from the Cu (110) surface using a new Monte Carlo simulation and putting emphasis on high order lateral interaction. According to our simulated TPD spectra, for β=10 K/s the maximum desorption rate occurs at Tm=218.6 K. Furthermore, analysis of simulated TPD spectra of CO desorption shows that it is strongly lateral-interactive and results an activation energy of CO desorption from Cu (110) that is Ed=66.6 Kj/mol. These simulated results are compared with other reported results and show excellent agreement. After that we have investigated the kinetics and mechanism of desorption of CO 2 from the Cu (100) surface using a Monte Carlo simulation. According to our simulated TPD spectra, for β=0.5 K/s the maximum desorption rate occurs at Tm=89.7 K. Analysis of simulated TPD spectra of CO 2 desorption shows that it is not strongly lateral-interactive and results in an activation energy of CO desorption from Cu (100) that is Ed=25.2 Kj/mol. Finally, the CO / Cu (110) system is compared with the CO 2/ Cu (100) system.
INTERFACE AND STEP LOCALIZED PHONON MODES BETWEEN TWO TRUNCATED THIN FILMS
Authors: TAMINE M. , BOUMRAR H. , RAFIL O.
Published: May 2004

We have carried out the calculations of vibrational dynamics in the low-dimensional structure with dimensions on the nanometer scale by using the matching formalism. The nanostructure model consists in the surface step produced at a perpendicular interface between two truncated thin films with different thickness. The theoretical approach determines the vibrational field in the direction where the translation symmetry is broken. The calculation concerns in particular the phonon dispersion curves localized on the interface and step edge, and employs the matching procedure in the harmonic approximation. The nearest and next nearest neighbors elastic force constants between the mass sites in the model, as well as a modification of the elastic strain field induced by the presence of the step, are considered. Analytic expressions are obtained for the phonon dispersion relations of the localized surface and edge elastic waves and the bulk phonons near a step. The breakdown of translational symmetry perpendicular to the step edge gives rise to several Raleigh-like branches localized in the neighborhood of step and interface. The effects of varying the elastic force constants at an interface and the strain field parameter near the step are studied. These factors influence the number of localized modes as well as their frequency, intensity and attenuation.
ELECTRICAL RESISTIVITY OF NANOSTRUCTURED PLATINUM AND GOLD THIN FILMS
Authors: SALVADORI M. C. , VAZ A. R. , FARIAS R. J. C. , CATTANI M.
Published: May 2004

We have measured, at room temperature, the resistivity, the surface roughness and the lateral surface correlation lengths of nanostructured platinum and gold thin films. The films' thickness d, deposited by vacuum arc plasma, is in the range 1.31≤d≤11.66 nm for platinum and 1.77≤d≤10.46 nm for gold. A theoretical estimate of our experimental data has been made.
POSITRON ANNIHILATION AND XRD FOR DETECTING Al ALLOYS (50XX)
Authors: BADAWI EMAD
Published: May 2004

The positron annihilation parameter (mean lifetime) increases with increasing Mg contents for annealed and quenched samples (50XX). Positron parameter τ, s (Doppler broadening) increase with increasing Q.T for the same (50XX). The preferred orientation is one of the most important parameters that can be observed by XRD for materials, for such measurements in our observation: the dependence of the preferred orientation on the Mg content, the dependence of the preferred orientation on the Q.T, and the dependence of the preferred orientation on the degree of deformation.
ATOMISTIC MODELING OF Pt DEPOSITION ON Cu(111) AND Cu DEPOSITION ON Pt(111)
Authors: CANZIAN ADRIÁN , MOSCA HUGO O. , BOZZOLO GUILLERMO
Published: May 2004

A modeling analysis of the growth mode of submonolayer amounts of Pt on Cu(111) and Cu on Pt(111) for different coverages and temperatures reproduces the known experimental behavior. An atom-by-atom analysis of the energetics using the BFS method for alloys provides a simple explanation of the underlying mechanisms leading to the observed behavior.
DFT STUDY OF THE FORMATION OF CH2=CF2 THROUGH BOTH METHYLENE INSERTION AND β-FLUORIDE ELIMINATION ON THE Ag(111) SURFACE
Authors: LIN JYH SHING , CHOU WEN-CHI
Published: May 2004

Total energy calculations based on (1) density functional theory (DFT) in connection with ultrasoft pseudopotential and generalized gradient spin-polarized approximation (GGSA) and (2) the partial structural constraint path minimization (PSCPM) method have been used to investigate the energetically more favorable pathway for methylene ( CH 2) insertion into the Ag–CF 3 bond followed by β-fluoride elimination to generate an isolated CH 2= CF 2( g ) above the Ag(111) surface. The diffusion of the fcc-hollow site of CF 3( ads ) toward the bridge site of CH 2( ads ) is proposed as an energe*tically more favorable path for CH 2 insertion into the Ag–CF 3 bond to form the bridge site of CH 2 CF 3( ads ) on the Ag(111) surface. Then we proceed with β-fluoride elimination to form an isolated CH 2= CF 2( g ) and the bridge site of F (ads) on the Ag(111) surface. Our calculated energy barrier for β-fluoride elimination is 0.715 eV higher than that for CH 2 insertion on the Ag(111) surface. These calculated results imply that β-fluoride elimination rather than CH 2 insertion on the Ag(111) surface controls the CH 2= CF 2( g ) formation rate as observed from temperature-programmed reaction (TPR) experimental data. Finally, we attribute these different energy barriers to the different transition state structures — largely distorted seven-centered versus less distorted four-centered — involved in these two different processes.
The calcium-dependent activity of large-conductance, calcium-activated K+ channels is enhanced by Pyk2- and Hck-induced tyrosine phosphorylation
Authors: Ling Shizhang , Sheng Jian-Zhong , Braun Andrew P.
Published: May 2004

Recent results showing that large-conductance, calcium-activated K+ (BKCa) channels undergo direct tyrosine phosphorylation in the presence of c-Src tyrosine kinase have suggested the involvement of these channels in Src-mediated signaling pathways. Given the important role for c-Src in integrin-mediated signal transduction, we have examined the potential regulation of BKCa channels by proline-rich tyrosine kinase 2 (Pyk2), a calcium-sensitive tyrosine kinase activated upon integrin stimulation. Transient coexpression of murine BKCa channels with either wild-type Pyk2 or hematopoietic cell kinase (Hck), a Src-family kinase, led to an enhancement of BKCa channel activity over the range of 1–10 μM free calcium, whereas coexpression with catalytically inactive forms of either kinase did not significantly alter BKCa gating compared with channels expressed alone. In the presence of either wild-type Pyk2 or Hck, BKCa α-subunits were found to undergo tyrosine phosphorylation, as determined by immunoprecipitation and Western blotting strategies. However, tyrosine phosphorylation of the BKCa α-subunit was not detected for channels expressed alone or together with inactive forms of either Pyk2 or Hck. Interestingly, wild-type, but not inactive, Pyk2 was also present in BKCa channel immunoprecipitates, suggesting that Pyk2 may coassociate with the BKCa channel complex after phosphorylation. Collectively, the observed modulation and phosphorylation of BKCa channels by Pyk2 and a Src-family kinase may reflect a general cellular mechanism by which G protein-coupled receptor and/or integrin activation leads to the regulation of membrane ion channels.
Fiber type and temperature dependence of inorganic phosphate: implications for fatigue
Authors: Debold E. P. , Dave H. , Fitts R. H.
Published: May 2004

Elevated levels of Pi are thought to cause a substantial proportion of the loss in muscular force and power output during fatigue from intense contractile activity. However, support for this hypothesis is based, in part, on data from skinned single fibers obtained at low temperatures (≤15°C). The effect of high (30 mM) Pi concentration on the contractile function of chemically skinned single fibers was examined at both low (15°C) and high (30°C) temperatures using fibers isolated from rat soleus (type I fibers) and gastrocnemius (type II fibers) muscles. Elevating Pi from 0 to 30 mM at saturating free Ca2+ levels depressed maximum isometric force (Po) by 54% at 15°C and by 19% at 30°C ( P < 0.05; significant interaction) in type I fibers. Similarly, the Po of type II fibers was significantly more sensitive to high levels of Pi at the lower (50% decrease) vs. higher temperature (5% decrease). The maximal shortening velocity of both type I and type II fibers was not significantly affected by elevated Pi at either temperature. However, peak fiber power was depressed by 49% at 15°C but by only 16% at 30°C in type I fibers. Similarly, in type II fibers, peak power was depressed by 40 and 18% at 15 and 30°C, respectively. These data suggest that near physiological temperatures and at saturating levels of intracellular Ca2+, elevated levels of Pi contribute less to fatigue than might be inferred from data obtained at lower temperatures.
C-peptide corrects endoneurial blood flow but not oxidative stress in type 1 BB/Wor rats
Authors: Stevens Martin J. , Zhang Weixian , Li Fei , Sima Anders A. F.
Published: May 2004

Oxidative stress and neurovascular dysfunction have emerged as contributing factors to the development of experimental diabetic neuropathy (EDN) in streptozotocin-diabetic rodents. Additionally, depletion of C-peptide has been implicated in the pathogenesis of EDN, but the mechanisms of these effects have not been fully characterized. The aims of this study were therefore to explore the effects of diabetes on neurovascular dysfunction and indexes of nerve oxidative stress in type 1 bio-breeding Worcester (BB/Wor) rats and type 2 BB Zucker-derived (ZDR)/Wor rats and to determine the effects of C-peptide replacement in the former. Motor and sensory nerve conduction velocities (NCVs), hindlimb thermal thresholds, endoneurial blood flow, and indicators of oxidative stress were evaluated in nondiabetic control rats, BB/Wor rats, BB/Wor rats with rat II C-peptide replacement (75 nmol C-peptide·kg body wt−1·day−1) for 2 mo, and diabetes duration-matched BBZDR/Wor rats. Endoneurial perfusion was decreased and oxidative stress increased in type 1 BB/Wor rats. C-peptide prevented NCV and neurovascular deficits and attenuated thermal hyperalgesia. Inhibition of nitric oxide (NO) synthase, but not cyclooxygenase, reversed the C-peptide-mediated effects on NCV and nerve blood flow. Indexes of oxidative stress were unaffected by C-peptide. In type 2 BBZDR/Wor rats, neurovascular deficits and increased oxidative stress were unaccompanied by sensory NCV slowing or hyperalgesia. Therefore, nerve oxidative stress is increased and endoneurial perfusion decreased in type 1 BB/Wor and type 2 BBZDR/Wor rats. NO and neurovascular mechanisms, but not oxidative stress, appear to contribute to the effects of C-peptide in type 1 EDN. Sensory nerve deficits are not an inevitable consequence of increased oxidative stress and decreased nerve perfusion in a type 2 diabetic rodent model.
Synchronization and entrainment of cytoplasmic Ca2+oscillations in cell clusters prepared from single or multiple mouse pancreatic islets
Authors: Zarkovic Milos , Henquin Jean-Claude
Published: May 2004

In contrast to pancreatic islets, isolated β-cells stimulated by glucose display irregular and asynchronous increases in cytoplasmic Ca2+concentration ([Ca2+]i). Here, clusters of 5–30 cells were prepared from a single mouse islet or from pools of islets, loaded with fura-2, and studied with a camera-based system. [Ca2+]ioscillations were compared in pairs of clusters by computing the difference in period and a synchronization index λ. During perifusion with 12 mM glucose, the clusters exhibited regular [Ca2+]ioscillations that were quasi-perfectly synchronized (Δ period of 1.4% and index λ close to 1.0) between cells of each cluster. In contrast, separate clusters were not synchronized, even when prepared from one single islet. Pairs of clusters neighboring on the same coverslip were not better synchronized than pairs of clusters examined separately (distinct coverslips). We next attempted to synchronize clusters perifused with 12 mM glucose by applying external signals. A single pulse of 20 mM glucose, 10 mM amino acids, or 10 μM tolbutamide transiently altered [Ca2+]ioscillations but did not reset the clusters to oscillate synchronously. On a background of 12 mM glucose, repetitive applications (1 min/5 min) of 10 μM tolbutamide, but not of 20 mM glucose, synchronized separate clusters. Our results identify a level of β-cell heterogeneity intermediate between single β-cells and the whole islet. They do not support the idea that substances released by islet cells serve as paracrine synchronizers. However, synchronization can be achieved by an external signal, if this signal has a sufficient strength to overwhelm the intrinsic rhythm of glucose-induced oscillations and is repetitively applied.
Mechanical stretch and progesterone differentially regulate activator protein-1 transcription factors in primary rat myometrial smooth muscle cells
Authors: Mitchell Jennifer A. , Shynlova Oksana , Langille B. Lowell , Lye Stephen J.
Published: May 2004

During pregnancy, stretch of the uterus, imposed by the growing fetus, is an important signal for the induction of genes involved in the onset of labor. In this study, the expression of activator protein-1 (AP-1) family mRNAs in response to in vitro stretch was investigated in myometrial cells. Rat primary myometrial smooth muscle cells were plated onto collagen I-coated Flex I culture plates and subjected to 25% static stretch on day 4 of culture. Static stretch induced an increase in the expression of c -fos, fosB, fra-1, c -jun, and junB. The expression of both c -fos and junB was maximally induced at 30 min by static stretch. The peak induction for fosB and c -jun occurred at 1 h, whereas the peak of fra-1 induction occurred between 1 and 2 h after application of stretch. Treatment of myometrial cells with progesterone (100 nM, 400 nM, 1 μM) for 1 or 6 h before the application of static stretch did not affect the magnitude of the c -fos response. However, 24 h of progesterone exposure reduced the magnitude of c -fos and fosB stretch induction at both the 400 nM and 1 μM doses. These data indicate that several members of the AP-1 family are stretch-responsive genes in myometrial smooth muscle cells. This response can be attenuated by pretreatment with progesterone; however, the requirement for longer pretreatment times suggests that the inhibitory actions of progesterone do not occur through a direct action of the progesterone receptor within the promoter regions of AP-1 genes.
Discordant effects of a chronic physiological increase in plasma FFA on insulin signaling in healthy subjects with or without a family history of type 2 diabetes
Authors: Kashyap Sangeeta R. , Belfort Renata , Berria Rachele , Suraamornkul Swangjit , Pratipranawatr Thongchai , Finlayson Jean , Barrentine Andrea , Bajaj Mandeep , Mandarino Lawrence , DeFronzo Ralph , Cusi Kenneth
Published: May 2004

Muscle insulin resistance develops when plasma free fatty acids (FFAs) are acutely increased to supraphysiological levels (∼1,500–4,000 μmol/l). However, plasma FFA levels >1,000 μmol/l are rarely observed in humans under usual living conditions, and it is unknown whether insulin action may be impaired during a sustained but physiological FFA increase to levels seen in obesity and type 2 diabetes mellitus (T2DM) (∼600–800 μmol/l). It is also unclear whether normal glucose-tolerant subjects with a strong family history of T2DM (FH+) would respond to a low-dose lipid infusion as individuals without any family history of T2DM (CON). To examine these questions, we studied 7 FH+ and 10 CON subjects in whom we infused saline (SAL) or low-dose Liposyn (LIP) for 4 days. On day 4, a euglycemic insulin clamp with [3-3H]glucose and indirect calorimetry was performed to assess glucose turnover, combined with vastus lateralis muscle biopsies to examine insulin signaling. LIP increased plasma FFA ∼1.5-fold, to levels seen in T2DM. Compared with CON, FH+ were markedly insulin resistant and had severely impaired insulin signaling in response to insulin stimulation. LIP in CON reduced insulin-stimulated glucose disposal (Rd) by 25%, insulin-stimulated insulin receptor tyrosine phosphorylation by 17%, phosphatidylinositol 3-kinase activity associated with insulin receptor substrate-1 by 20%, and insulin-stimulated glycogen synthase fractional velocity over baseline (44 vs. 15%; all P < 0.05). In contrast to CON, a physiological elevation in plasma FFA in FH+ led to no further deterioration in Rdor to any additional impairment of insulin signaling. In conclusion, a 4-day physiological increase in plasma FFA to levels seen in obesity and T2DM impairs insulin action/insulin signaling in CON but does not worsen insulin resistance in FH+. Whether this lack of additional deterioration in insulin signaling in FH+ is due to already well-established lipotoxicity, or to other molecular mechanisms related to insulin resistance that are nearly maximally expressed early in life, remains to be determined.