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PubMed2006

Surface-directed boundary flow in microfluidic channels.

Channel geometry combined with surface chemistry enables a stable liquid boundary flow to be attained along the surfaces of a 12 microm diameter hydrophilic glass fiber in a closed semi-elliptical channel. Surface free energies and triangular corners formed by PDMS/glass fiber or OTS/glass fiber surfaces are shown to be responsible for the experimentally observed wetting phenomena and formation of liquid boundary layers that are 20-50 microm wide and 12 microm high. Viewing this stream through a 20 microm slit results in a virtual optical window with a 5 pL liquid volume suitable for cell counting and pathogen detection. The geometry that leads to the boundary layer is a closed channel that forms triangular corners where glass fiber and the OTS coated glass slide or PDMS touch. The contact angles and surfaces direct positioning of the fluid next to the fiber. Preferential wetting of corner regions initiates the boundary flow, while the elliptical cross-section of the channel stabilizes the microfluidic flow. The Young-Laplace equation, solved using fluid dynamic simulation software, shows contact angles that exceed 105 degrees will direct the aqueous fluid to a boundary layer next to a hydrophilic fiber with a contact angle of 5 degrees. We believe this is the first time that an explanation has been offered for the case of a boundary layer formation in a closed channel directed by a triangular geometry with two hydrophobic wetting edges adjacent to a hydrophilic surface.

Dimethylpolysiloxanes↗

PubMedDate not supplied

One-pot glyco-affinity precipitation purification for enhanced proteomics: the flexible alignment of solution-phase capture/release and solid-phase separation.

A one-pot affinity precipitation purification of carbohydrate-binding protein was demonstrated by designing thermally responsive glyco-polypeptide polymers, which were synthesized by selective coupling of pendant carbohydrate groups to a recombinant elastin-like triblock protein copolymer (ELP). The thermally driven inverse transition temperature of the ELP-based triblock polymer is maintained upon incorporation of carbohydrate ligands, which was confirmed by differential scanning calorimetry and (1)H NMR spectroscopy experiments. As a test system, lactose derivatized ELP was used to selectively purify a galactose-specific binding lectin through simple temperature-triggered precipitation in a high level of efficiency. Potential opportunities might be provided for enhanced proteomic, cell isolation as well as pathogen detection applications.

Amino Acid Sequence↗

PubMed2001

Diagnostic molecular microbiology in laboratory animal health monitoring and surveillance programs.

Molecular microbiology provides a rapid, reliable, sensitive, and specific means of detecting pathogens in laboratory animals. The author discusses the interpretation of the results of molecular microbiological testing done in conjunction with serologic, bacteriologic, and histopathologic tests, focusing on molecular microbiology as it fits in an overall program of animal health diagnostic profiling.

Animals↗

PubMed2006

The innate immune system 'puzzle'.

Detecting pathogen invasion and regulating homeostatic processes are two essential functions of myriad non-Toll-like innate immune proteins.

Animals↗

PubMed2003

Infectious complications in patients with acute promyelocytic leukaemia treated with the AIDA regimen.

Infections represent a frequent complication of chemotherapy used for acute myeloid leukaemia (AML) and are associated with important toxicity frequently leading to treatment discontinuation. Acute promyelocytic leukaemia (APL) is a unique AML subset requiring tailored therapy including all-trans retinoic acid and anthracycline-based chemotherapy. We analysed in this study the incidence and type of infections complicating the clinical course of 89 consecutive APL patients receiving the AIDA protocol at a single institution. A total of 179 febrile episodes were registered during induction and consolidation, 52% of which were of unknown origin. Infections were clinically and microbiologically documented in 10.6 and 37.4% of cases, respectively. Coagulase-negative staphylococci represented the major cause of septicaemia (28%) and were more frequently isolated during induction, whereas viridans group streptococci, the second pathogen most frequently isolated from blood (27%), represented the principal pathogen detected during consolidation and were significantly associated with mucositis. Gram-negative bacteria accounted for 33.3% of all blood isolates. Fungal infections were only occasionally observed. Bloodstream infections in APL patients were compared with those documented in 271 consecutive patients affected by other subtypes of AML. The incidence of total septicaemia episodes, of staphylococcal bacteraemias and of fungaemias was significantly higher in patients with other AMLs. Empirical antibiotic therapy with ceftriaxone plus amikacin was effective in 73% of APL cases, most of the remaining cases being successfully managed by the addition of teicoplanin. One single death apparently related to infectious complication was recorded. Overall, infections led to antileukaemic treatment withdrawal in six patients, five of whom currently remain in haematologic remission for 13-106 months. These results indicate that a particular pattern of infections is observed in APL patients receiving ATRA plus anthracycline-based chemotherapy and that these appear to be effectively counteracted by standard management.

Adolescent↗

PubMed2005

Thermally-actuated, phase change flow control for microfluidic systems.

An easy to implement, thermally-actuated, noninvasive method for flow control in microfluidic devices is described. This technique takes advantage of the phase change of the working liquid itself-the freezing and melting of a portion of a liquid slug-to noninvasively close and open flow passages (referred to as a phase change valve). The valve was designed for use in a miniature diagnostic system for detecting pathogens in oral fluids at the point of care. The paper describes the modeling, construction, and characteristics of the valve. The experimental results favorably agree with theoretical predictions. In addition, the paper demonstrates the use of the phase change valves for flow control, sample metering and distribution into multiple analysis paths, sealing of a polymerase chain reaction (PCR) chamber, and sample introduction into and withdrawal from a closed loop. The phase change valve is electronically addressable, does not require any moving parts, introduces only minimal dead volume, is leakage and contamination free, and is biocompatible.

Microfluidic Analytical Techniques↗

PubMed2003

Functional approach to investigate Lp(a) in ischaemic heart and cerebral diseases.

BACKGROUND: Lp(a), a major cardiovascular risk factor, contains a specific apolipoprotein, apo(a), which by virtue of structural homology with plasminogen inhibits the formation of plasmin, the fibrinolytic enzyme. A number of clinical reports support the role of Lp(a) as a cardiovascular or cerebral risk factor, and experimental data suggest that it may contribute to atherothrombosis by inhibiting fibrinolysis. DESIGN: A well-characterized model of a fibrin surface and an apo(a)-specific monoclonal antibody were used to develop a functional approach to detect pathogenic Lp(a). The assay is based on the competitive binding of Lp(a) and plasminogen for fibrin, and quantifies fibrin-bound Lp(a). High Lp(a) binding to fibrin is correlated with decreased plasmin formation. In a transversal case-control study we studied 248 individuals: 105 had a history of ischaemic cardiopathy (IC), 52 had cerebro-vascular disease (CVD) of thrombotic origin, and 91 were controls. RESULTS: The remarkably high apo(a) fibrin-binding in CVD (0.268 +/- 0.15 nmol L-1) compared with IC (0.155 +/- 0.12 nmol L-1) suggests the existence of peculiar and poorly understood differences in pro- or anti-thrombotic mechanisms in either cerebral and/or coronary arteries. CONCLUSIONS: Our results demonstrated that Lp(a) fibrin-binding and small Apo(a) isoforms are associated with athero-thrombotic disease.

Adult↗

PubMed2000

[Contagious impetigo--pathogen spectrum and therapeutic consequences].

OBJECTIVE: The aim of this prospective study was to compare the clinical picture of contagious impetigo (C.I.) with the causative organism and to generate data of the susceptibility of bacteria as the basis for adequate therapy. PATIENTS AND METHODS: In 126 patients with C.I. (86 children, 66 of them younger than 10 years) bacterial swabs were taken and antibiotic sensitivity testing for isolated organisms was tested. RESULTS: In all cases in which contents of vesicles or pustules were analysed, Staphylococcus aureus was the only pathogen isolated. In non-bullous variants of C.I. Staphylococcus aureus was the most often isolated organism as well. Both staphylococci and streptococci were isolated in 12 cases, whereas in just 9 cases streptococci were the only pathogen detected. All Staphylococcus aureus isolates were sensitive to flucloxacillin and cefotaxime. Erythromycin-resistance amounted to more than 20 percent. The percentage of resistant staphylococci against the predominantly topically applied antibiotics fusidinic acid and mupirocin was 2 and 0 per cent, respectively. CONCLUSION: For all manifestations of C.I. Staphylococcus aureus is at present the leading organism which has to be taken into consideration for treatment. If oral antibiotic therapy is indicated, penicillinase-stable penicillins or cephalosporins, preferably of the cefalexin-type, are the drugs of choice. Macrolides are no longer recommended for initiating of C.I. treatment.

Adult↗

PubMed2003

[American cutaneous leishmaniasis: special features in diagnosis and therapy].

HISTORY AND CLINICAL FINDINGS: Three weeks after returning from a trip to Guatemala, a 33-year-old man developed two ulcers with indurated edges on his right leg and painful lymph nodes in the right groin. His general condition was not impaired. EXAMINATIONS: Histological examination revealed cellular infiltrates of the corium by lymphocytes and plasma cells, always accompanied by epithelial cells and multinuclear giant cells. Special stainings were unable to detect pathogens but Leishmania brasiliensis was identified using PCR. The Leishmania culture remained negative. THERAPY AND COURSE: After 7-day intravenous therapy with 20 mg/kg/d pentostam (pentavalent antimonial compound), the patient developed gastrointestinal complaints, coupled with a marked elevation of transaminases. Therapy was discontinued until the transaminase values normalized, then continued in reduced dosage (12 mg/kg body weight) for 23 days. The ulcers and lymphadenitis healed under this therapy. CONCLUSION: The diagnosis of American cutaneous Leishmaniasis may be complicated by the relative lack of pathogens in the lesions. PCR diagnosis are very helpful here. The therapy must be systemic owing to the danger of progression to mucocutaneous Leishmaniasis. The standard therapeutic pentostam has, however, a high rate of side effects and administration is exclusively intravenous.

Adult↗

PubMed1991

[Bacteriologic findings before and in transcervical chorionic villi biopsy and their clinical relevance].

Between August 1987 and May 1989, bacteriological examinations of smears from the cervical canal was performed in 358 pregnant women, who underwent transcervical sampling of chorionic villi. The outcome of 349 of these pregnancies is documented. 12 of these patients (3.5%) had an artificial abortion for genetic reasons. In 12 other patients, the pregnancy ended before 28 weeks (one child surviving). Microbiological examinations showed that in 187 women (52%), it was possible to culture one or more microorganisms from the cervical canal. The most frequently detected pathogen was Chlamydia trachomatis (111 women, 31%). In pregnancies, where more than one microorganism could be cultured, the risk of following abortion was 8.9 times higher than in those, where no pathogens could be found. In only two of the 12 women with a subsequent spontaneous abortion (16.6%), no microorganism could be found. The bacterial contamination of the cervical canal during TC-CVS seems to be a risk factor for subsequent abortion. Therefore, a bacteriological examination of cervical flora should be performed before as well as during TC-CVS, and antibiotic therapy should be initiated in case of positive results.

Abortion, Septic↗

PubMed2002

Final report on the safety assessment of human placental protein, hydrolyzed human placental protein, human placental enzymes, human placental lipids, human umbilical extract, placental protein, hydrolyzed placental protein, placental enzymes, placental lipids, and umbilical extract.

Various proteins, lipids, or other extracts from human or other animal placentas are described as cosmetic ingredients. Human Placental Protein comprises protein derived from human placentas. Placental Protein is derived from animal placentas. Similarly, Human Placental Lipids and Placental Lipids are the lipid fractions from the same source materials. Hydrolyzed Human Placental Protein and Hydrolyzed Placental Protein are produced from the respective protein extracts by acid, enzyme, or other hydrolysis methods. Human Placental Enzymes and Placental Enzymes are enzymes obtained by aqueous extraction of human or other animal placental material. Human Umbilical Extract and Umbilical Extract are unspecified extracts of material from human or other animal umbilical cords. Different materials called Human Placental Extracts and Placental Extracts, assumed to contain estrogenic hormones or other biologically active substances, are not recognized as cosmetic ingredients, even though the use of these ingredients in cosmetics have been reported to the Food and Drug Administration (FDA). Human-derived ingredients are prohibited from use under the provisions of the European Union cosmetics directive based on concerns about transmission of human spongiform encephalopathies and viral diseases, for example, human immunodeficiency virus (HIV). Umbilical Extract has precedent for unrestricted use in Japan, except for certain products. Most of these ingredients are described as hair-conditioning agents and miscellaneous skin-conditioning agents, although the umbilical extracts function as biological additives in cosmetics. Of the human-derived ingredients, only Human Placental Protein is currently reported to be used. Animal-derived placental proteins, hydrolyzed proteins, lipids, and enzymes were all currently reported to be used. No current uses of the umbilical extracts were reported. Most of the available data relates to placental derivatives that appear to have estrogenic or other biological activity. The one clinical study that appears to utilize proteinaceous material only reported no irritant reaction. Clearly, the available data are insufficient to support safety of these ingredients in cosmetics. The additional data needed include (1) skin sensitization at concentration of use; (2) gross pathology and histopathology in skin and other major organ systems associated with repeated exposures, and dermal reproductive and developmental toxicity data; (3) photosensitization; (4) one genotoxicity assay in a mammalian system; if positive, then a 2-year dermal carcinogenicity study using National Toxicology Program (NTP) methods may be needed; (5) ocular toxicity, if available. Any studies should be done on all ingredients unless chemical analysis data show similarity among ingredients. Because there is confusion and concern about the use of substances with estrogenic or other biological activity in cosmetic formulations, it was concluded that none of these ingredients used in cosmetics should deliver any metabolic/endocrine activity. In addition, any current use of these ingredients should be free of detectable pathogenic viruses or infectious agents.

Animals↗

PubMed2006

Genetic diversity of human metapneumovirus over 4 consecutive years in Australia.

The molecular epidemiologic profile of human metapneumovirus (hMPV) infection has likely been skewed toward certain genetic subtypes because of assay-design issues, and no comprehensive studies have been conducted to date. Here, reverse-transcription polymerase chain reaction was used to screen 10,319 specimens from patients presenting to hospitals with suspected respiratory tract infections during 2001-2004. After analysis of 727 Australian hMPV strains, 640 were assigned to 1 of 4 previously described subtypes. hMPV was the most common pathogen detected, and subtype B1 was the most common lineage. Concurrent, annual circulation of all 4 hMPV subtypes in our study population was common, with a single, usually different hMPV subtype predominating in each year.

Adolescent↗

PubMed1995

Non-Hodgkin malignant lymphomas and peripheral neuropathies--13 cases.

Non-Hodgkin's malignant lymphomas (NHML) are malignant lymphoid proliferations which may be of B or T cell type. Thirteen observations of an association between peripheral neuropathy and B type NHML are reported. None of the cases had evidence of meningeal propagation or neurotoxicity from chemotherapy. The NHML were classified according to the Working Formulation and Kiel classifications. The various mechanisms of peripheral neuropathy in these cases were split into four broad groups. Group I consisted of four cases in which the peripheral nerve lesions were directly linked to a propagation of malignant cells into the peripheral nervous system; this was revealed by autopsy and/or nerve biopsy. Malignant B cell proliferation was demonstrated in three out of four of these cases by immunolabelling of the infiltrates. Group II included three patients whose serum contained a monoclonal immunoglobulin (IgM) with antimyelin activity, and two who had pathological IgM deposits in endoneurial connective tissue. Group III comprised two cases. The immune dysfunction of the NHML was responsible for a Guillain-Barré syndrome in one, and for a chronic inflammatory demyelinating polyneuropathy in the other. Group IV included two patients in whom the mechanism of the peripheral neuropathy, although almost certainly directly related to the NHML, could not be determined beyond doubt. The peripheral neuropathy might have been a result of a paraneoplasic process or, possibly, an undetected lymphomatous invasion of nervous tissue. All these cases of clinically diverse peripheral neuropathy, which either occurred before the discovery of the haemopathy or arose as complications of it, are discussed along with similar observations reported in the literature. Immunolabelling of lymphomatous proliferations and nerves is now of considerable value for classifying and indicating the exact aetiology of the peripheral neuropathy. It can also detect pathogenic consequences of any associated monoclonal dysglobulinemia. In any event, a direct link between the peripheral neuropathy and NHML represents an indication for intensification of specific chemotherapy, which in some of our patients led to significant regression of the peripheral neuropathy. Nonetheless, in some cases, the link between peripheral neuropathy and NHML could not be established with certainty. Long-term follow-up is essential in such cases. The present results show the importance of a case by case study of patients with NHML and peripheral neuropathy.

Aged↗

PubMed1995

Determining the duration of Ixodes scapularis (Acari: Ixodidae) attachment to tick-bite victims.

The duration of tick attachment is one factor associated with risk for human infection caused by several tick-borne pathogens. We measured tick engorgement indices at known time intervals after tick attachment and used these indices to determine the length of time that ticks were attached to tick-bite victims in selected Rhode Island and Pennsylvania communities where the agents of Lyme disease and human babesiosis occur. The total body length and width as well as the length and width of the scutum were measured on nymphal and adult female Ixodes scapularis Say removed from laboratory animals at 0, 12, 24, 36, 48, 60, and 72 h after their attachment. Three engorgement indices were calculated at each time interval. In addition, engorgement indices measurements were recorded for 504 ticks submitted to a commercial laboratory for pathogen detection testing between 1990 and 1992. No detectable change was observed in the average engorgement indices for either nymphal or adult ticks between 0 and 24 h of attachment using any of the engorgement indices. After 24 h of tick attachment, all engorgement indices continuously increased: average indices for nymphs attached 36, 48, and 60 h were significantly different from those attached < or = 24 h and from each other. Similarly, average engorgement indices for adult ticks attached < or = 36 h were significantly different from those attached for 48 h or more. More than 60% of tick-bite victims removed adult ticks by 36 h of attachment, but only 10% found and removed the smaller nymphal ticks within the first 24 h of tick feeding. The duration of tick attachment may serve as a useful predictor of risk for acquiring various infections, such as Lyme disease and babesiosis, transmitted by I. scapularis. Regression equations developed herein correlate tick engorgement indices with duration of feeding. A table containing specific engorgement index prediction intervals calculated for both nymphs and adults will allow the practitioner or clinical laboratory to use easily measured tick engorgement indices to predict transmission risk by determining the duration of feeding by individual ticks.

Animals↗

PubMed2004

Sigmoidal curve-fitting redefines quantitative real-time PCR with the prospective of developing automated high-throughput applications.

Quantitative real-time PCR has revolutionized many aspects of genetic research, biomedical diagnostics and pathogen detection. Nevertheless, the full potential of this technology has yet to be realized, primarily due to the limitations of the threshold-based methodologies that are currently used for quantitative analysis. Prone to errors caused by variations in reaction preparation and amplification conditions, these approaches necessitate construction of standard curves for each target sequence, significantly limiting the development of high-throughput applications that demand substantive levels of reliability and automation. In this study, an alternative approach based upon fitting of fluorescence data to a four-parametric sigmoid function is shown to dramatically increase both the utility and reliability of quantitative real-time PCR. By mathematically modeling individual amplification reactions, quantification can be achieved without the use of standard curves and without prior knowledge of amplification efficiency. Combined with provision of quantitative scale via optical calibration, sigmoidal curve-fitting could confer the capability for fully automated quantification of nucleic acids with unparalleled accuracy and reliability.

Calibration↗

PubMed1979

Comparative epidemiology of two rotavirus serotypes and other viral agents associated with pediatric gastroenteritis.

Human rotavirus (HRV) type 1 or 2, adenovirus, or non-cultivatable 27 nm virus-like particles were demonstrated by electron microscopy and/or rotavirus ELISA in fecal samples from 45.5% of 604 gastroenteritis inpatients, 25.0% of 200 gastroenteritis outpatients and 6.0% of 812 control subjects, all sampled at Children's Hospital National Medical Center. Washington, DC. Rotaviruses were the most common pathogens detected as 39% and 22% of gastroenteritis inpatients and outpatients, respectively, shed HRV. About three-fourths of the rotaviruses were type 2, which was prevalent during five successive epidemic years from January, 1974, through June, 1978. HRV type 1 was detected in the last four successive epidemic years and represented nearly half of the HRV infections observed among gastroenteritis inpatients during the year 1977--1978. Both rotavirus serotypes were detected most often in the month of January, when 71% of 123 gastroenteritis inpatients and 62% of 34 gastroenteritis outpatients shed one of these viruses. Uncultivatable adenoviruses were detected significantly more frequently in stools from patients with gastroenteritis (3.9%) than from control subjects (0.6%), suggesting that these viruses played a role in acute enteric disease. The frequency of detection of 27 nm particles was not significantly different in gastroenteritis and control patients. Numerically, HRV infection was detected most often in gastroenteritis inpatients who were 10 through 12 months of age. The group of gastroenteritis inpatients with the highest percentage of HRV infection was 13 through 15 months of age. The excess of type 2 HRV infection relative to type 1 infection was especially large in those aged 7 through 24 months. Lower socioeconomic status or greater crowding appeared to be associated with the occurrence of rotavirus infection earlier in life and earlier in the epidemic year.

Adenoviridae↗

PubMed1984

Lack of significant person-to-person spread of swine influenza-like virus following fatal infection in an immunocompromised child.

In February 1982, a four-year-old Nevada girl with acute lymphoblastic leukemia in remission was hospitalized with fulminant pneumonia and died eight days later at a hospital in California. An influenza virus was the only pathogen detected, and was present in both antemortem and postmortem specimens. The virus was closely related antigenically to A/New Jersey/8/76 (H1N1) and had a genome very similar to a contemporary enzootic swine influenza virus. The patient had had no known contact with swine, and the source of infection could not be determined. Only five possible secondary cases could be detected by retrospective investigation of 62 contacts, and there was no evidence of spread to the general community. Swine influenza viruses circulate among pigs in the United States annually, and it is likely that sporadic transmissions to humans will continue to be detected. Nevertheless, person-to-person spread under these circumstances appears to be limited.

Adolescent↗

PubMed2001

Long-term neurological outcome of acute encephalitis.

To understand the viral etiology of acute childhood encephalitis in Elaziğ, Eastern Turkey, 36 children aged between 4 months and 14 years who were treated in a regional medical center between January 1995 and June 1999 were studied. Viral etiology was identified in 16 of 34 (47.1 per cent) cases and the most frequently detected pathogens was mumps (seven cases, 20.6 per cent). No specific etiology was found in 18 (52.9 per cent) cases. Among the survivors, mental and/or focal neurological deficits persisted in 18 (52.9 per cent). Two children died and 32 survived, of whom 16 were left with no neurological sequel, 10 had persistent neurological sequel, and eight recovered with some degree of handicap. Improvement in the general health and sanitation of the population, and the universal use and development of new vaccination will significantly reduce the incidence of viral encephalitis.

Acute Disease↗