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Biomedical subjects

J Johnson

Publications and source records attributed to J Johnson.

At least 37 records · Page 2Linked to original sources
PubMed2004

The Spirit Rover's Athena science investigation at Gusev Crater, Mars.

The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.

Atmosphere↗
PubMed2004

Antibody response to pneumolysin and to pneumococcal capsular polysaccharide in healthy individuals and Streptococcus pneumoniae infected patients.

BACKGROUND: Animal experiments have shown that antibodies against capsular polysaccharide enhance phagocytosis of pneumococcal bacteria and that antibodies against pneumolysin are anti-inflammatory and prevent pneumococcal invasion. It is not known if an antibody response to pneumolysin can be acquired from natural exposure to pneumococcal bacteria or how the concentration of pneumolysin antibody at the mucosal surface compares with that of antibodies against pneumococcal capsular polysaccharide. This study used an equal potency method to measure specific antibody concentrations against pneumolysin and pneumococcal capsular polysaccharides in order to facilitate comparative estimates of concentrations in saliva and serum. The results may provide experimental information as a basis for an improved pneumococcal vaccine strategy. RESULTS: Healthy individuals had higher IgM and IgG antibody concentrations against capsular polysaccharide than against pneumolysin in both saliva and serum, but for IgA the converse was true. Patients with acute pneumococcal infection had significantly lower concentrations of specific IgG antibodies against both antigens than the healthy group. These patients also had significantly higher concentrations of IgM antibody against both antigens than the healthy control group. DISCUSSION: Healthy individuals acquire a comparatively lower concentration of antibody to pneumolysin than to pneumococcal capsular polysaccharides from natural exposure to pneumococcal bacteria. Patients infected by pneumococcal bacteria have lower specific IgG antibody concentrations to both antigens than healthy individuals. These findings support the view that pneumolysin could potentially be used as a vaccine. For enhanced effectiveness, it could be used as a supplement to Pneumovax((R))II rather than as a replacement. The two acquired antibodies, i.e. to pneumolysin and to capsular polysaccharide, could then play their protective roles at different stages in the course of pneumococcal infection, and together contribute to an effective immune defence against Streptococcus pneumoniae.

Adult↗
PubMed2004

Electrical and neurotransmitter activity of mature neurons derived from mouse embryonic stem cells by Sox-1 lineage selection and directed differentiation.

Sx1TV2/16C is a mouse embryonic stem (ES) cell line in which one copy of the Sox1 gene, an early neuroectodermal marker, has been targeted with a neomycin (G418) selection cassette. A combination of directed differentiation with retinoic acid and G418 selection results in an enriched neural stem cell population that can be further differentiated into neurons. After 6-7 days post-plating (D6-7PP) most neurons readily fired tetrodotoxin (TTX)-sensitive action potentials due to the expression of TTX-sensitive Na(+) and tetraethylammonium (TEA)-sensitive K(+) channels. Neurons reached their maximal cell capacitance after D6-7PP; however, ion channel expression continued until at least D21PP. The percentage of cells receiving spontaneous synaptic currents (s.s.c.) increased with days in culture until 100% of cells received a synaptic input by D20PP. Spontaneous synaptic currents were reduced in amplitude and frequency by TTX, or upon exposure to a Ca(2+)-free, 2.5 mm Mg(2+) saline. S.s.c. of rapid decay time constants were preferentially blocked by the nonNMDA glutamatergic receptor antagonists CNQX or NBQX. Ca(2+) levels within ES cell-derived neurons increased in response to glutamate receptor agonists l-glutamate, AMPA, N-methyl-d-aspartate (NMDA) and kainic acid and to acetylcholine, ATP and dopamine. ES cell-derived neurons also generated cationic and Cl(-)-selective currents in response to NMDA and glycine or GABA, respectively. It was concluded that ES-derived neurons fire action potentials, receive excitatory and inhibitory synaptic input and respond to various neurotransmitters in a manner akin to primary central neurons.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2004

Natural atypical Listeria innocua strains with Listeria monocytogenes pathogenicity island 1 genes.

Identification of bona fide Listeria isolates into the six species of the genus normally requires only a few tests. Aberrant isolates do occur, but even then only one or two extra confirmatory tests are generally needed for identification to species level. We have discovered a hemolytic-positive, rhamnose and xylose fermentation-negative Listeria strain with surprising recalcitrance to identification to the species level due to contradictory results in standard confirmatory tests. The issue had to be resolved by using total DNA-DNA hybridization testing and then confirmed by further specific PCR-based tests including a Listeria microarray assay. The results show that this isolate is indeed a novel one. Its discovery provides the first fully documented instance of a hemolytic Listeria innocua strain. This species, by definition, is typically nonhemolytic. The L. innocua isolate contains all the members of the PrfA-regulated virulence gene cluster (Listeria pathogenicity island 1) of L. monocytogenes. It is avirulent in the mouse pathogenicity test. Avirulence is likely at least partly due to the absence of the L. monocytogenes-specific allele of iap, as well as the absence of inlA, inlB, inlC, and daaA. At least two of the virulence cluster genes, hly and plcA, which encode the L. monocytogenes hemolysin (listeriolysin O) and inositol-specific phospholipase C, respectively, are phenotypically expressed in this L. innocua strain. The detection by PCR assays of specific L. innocua genes (lin0198, lin0372, lin0419, lin0558, lin1068, lin1073, lin1074, lin2454, and lin2693) and noncoding intergenic regions (lin0454-lin0455 and nadA-lin2134) in the strain is consistent with its L. innocua DNA-DNA hybridization identity. Additional distinctly different hemolytic L. innocua strains were also studied.

Animals↗
PubMed2003

Assessment of a DJ-1 (PARK7) polymorphism in Finnish PD.

Mutations in DJ-1 are a cause of autosomal recessive parkinsonism. Polymorphism of genes implicated in hereditary forms of parkinsonism may be a predisposing factor in sporadic Parkinson's disease (PD). The authors analyzed whether a polymorphism (g.168_185del) within exon 1 of DJ-1 contributes to the risk of sporadic PD in a Finnish case-control series. This gene does not play a major role in the genetic predisposition to PD in this population.

Adult↗
PubMed2003

Genetic and clinical characterization of patients with an interstitial duplication 15q11-q13, emphasizing behavioral phenotype and response to treatment.

The clinical significance of an interstitial duplication of (15)(q11-q13) remains unclear and controversial. The reported phenotypes vary widely and appear to be influenced by the parent of origin of the duplication. Aside from cases of dup(15) reported with autism, the behavioral phenotype of individuals with dup(15) has not been described. We present three families, two with intrachromosomal duplication (15)(q11-q13) ascertained because of developmental delay in a relative. Two families show clear evidence of multigenerational maternal inheritance. The individuals discussed in this paper have minor anomalies and developmental delays. In addition, we describe a behavioral phenotype which often includes attention deficit hyperactivity disorder (ADHD) and autistic spectrum disorder. Responses to medications used to manage these behaviors are also described, including a positive response to methylphenidate and a poor response to fluoxetine. The duplication in each presenting individual, and available family members, was investigated utilizing cytogenetic and molecular techniques including high resolution cytogenetics, fluorescence in situ hybridization (FISH), DNA methylation studies, and quantitative fluorescence PCR. High resolution cytogenetic techniques alone missed some cases, demonstrating the need to confirm results with other methods.

Child↗
PubMed2003

Surgical treatment of right-sided renal lymphoma with invasion of the caudal vena cava.

An eight-year-old, male castrated basset hound presenting with a three-month history of lethargy was examined. Diagnostic tests including radiography and ultrasonography showed a right-sided renal mass. A 99mTc diethylenetriamine penta-acetic acid scan demonstrated that this kidney was non-functional. At surgery, invasion of the caudal vena cava was found, and the renal segment of the vena cava and the right kidney were resected. The left renal vein was anastomosed to the more proximal vena cava using a polytetrafluoroethylene graft, and the dog recovered well. Two days postsurgery, the dog suffered an acute episode of aspiration pneumonia and was euthanased. The renal mass was diagnosed as lymphoma on histopathology.

Animals↗
PubMed2003

Contamination dose from photoneutron processes in bodily tissues during therapeutic radiation delivery.

Dose to the total body from induced radiation resulting from primary exposure to radiotherapeutic beams is not detailed in routine treatment planning though this information is potentially important for better estimates of health risks including secondary cancers. This information can also allow better management of patient treatment logistics, suggesting better timing, sequencing, and conduct of treatment. Monte Carlo simulations capable of taking into account all interactions contributing to the dose to the total body, including neutron scattering and induced radioactivity, provide the most versatile and accurate tool for investigating these effects. MCNPX code version 2.2.6 with full IAEA library of photoneutron cross sections is particularly suited to trace not only photoneutrons but also protons and heavy ion particles that result from photoneutron interactions. Specifically, the MCNPX code is applied here to the problem of dose calculations in traditional (non-IMRT) photon beam therapy. Points of calculation are located in the head, where the primary irradiation has been directed, but also in the superior portion of the torso of the ORNL Mathematical Human Phantom. We calculated dose contributions from neutrons, protons, deutrons, tritons and He-3 that are produced at the time of photoneutron interactions in the body and that would not have been accounted for by conventional radiation oncology dosimetry.

Humans↗
PubMed2003

Molecular characterization of gentamicin-resistant Enterococci in the United States: evidence of spread from animals to humans through food.

We evaluated the molecular mechanism for resistance of 360 enterococci for which the gentamicin MICs were >/=128 micro g/ml. The aac(6')-Ie-aph(2")-Ia, aph(2")-Ic, and aph(2")-Id genes were identified by PCR in isolates from animals, food, and humans. The aph(2")-Ib gene was not identified in any of the isolates. Two Enterococcus faecalis isolates (MICs > 1,024 micro g/ml) from animals failed to generate a PCR product for any of the genes tested and likely contain a new unidentified aminoglycoside resistance gene. Pulsed-field gel electrophoresis (PFGE) analysis showed a diversity of strains. However, 1 human and 18 pork E. faecalis isolates from Michigan with the aac(6')-Ie-aph(2")-Ia gene had related PFGE patterns and 2 E. faecalis isolates from Oregon (1 human and 1 grocery store chicken isolate) had indistinguishable PFGE patterns. We found that when a gentamicin-resistant gene was present in resistant enterococci from animals, that gene was also present in enterococci isolated from food products of the same animal species. Although these data indicate much diversity among gentamicin-resistant enterococci, the data also suggest similarities in gentamicin resistance among enterococci isolated from humans, retail food, and farm animals from geographically diverse areas and provide evidence of the spread of gentamicin-resistant enterococci from animals to humans through the food supply.

Animal Diseases↗
PubMed2003

Creatinine clearance and adverse hospital outcomes in patients with acute coronary syndromes: findings from the global registry of acute coronary events (GRACE).

OBJECTIVE: To determine whether creatinine clearance at the time of hospital admission is an independent predictor of hospital mortality and adverse outcomes in patients with acute coronary syndromes (ACS). DESIGN: A prospective multicentre observational study, GRACE (global registry of acute coronary events), of patients with the full spectrum of ACS. SETTING: Ninety four hospitals of varying size and capability in 14 countries across four continents. PATIENTS: 11 774 patients hospitalised with ACS, including ST and non-ST segment elevation acute myocardial infarction and unstable angina. MAIN OUTCOME MEASURES: Demographic and clinical characteristics, medication use, and in-hospital outcomes were compared for patients with creatinine clearance rates of > 60 ml/min (normal and minimally impaired renal function), 30-60 ml/min (moderate renal dysfunction), and < 30 ml/min (severe renal dysfunction). RESULTS: Patients with moderate or severe renal dysfunction were older, were more likely to be women, and presented to participating hospitals with more comorbidities than those with normal or minimally impaired renal function. In comparison with patients with normal or minimally impaired renal function, patients with moderate renal dysfunction were twice as likely to die (odds ratio 2.09, 95% confidence interval 1.55 to 2.81) and those with severe renal dysfunction almost four times more likely to die (odds ratio 3.71, 95% confidence interval 2.57 to 5.37) after adjustment for other potentially confounding variables. The risk of major bleeding episodes increased as renal function worsened. CONCLUSION: In patients with ACS, creatinine clearance is an important independent predictor of hospital death and major bleeding. These data reinforce the importance of increased surveillance efforts and use of targeted intervention strategies in patients with acute coronary disease complicated by renal dysfunction.

Adult↗
PubMed2003

On receiving the diagnosis of multiple sclerosis: managing the transition.

This article reports on one aspect of a wider study into multiple sclerosis (MS) specialist nurse roles in the UK. Insights gained from in-depth patient interviews are discussed in relation to literature regarding the meaning of health-related events, such as diagnosis. The findings of this project indicated that for many people, intense feelings of abandonment and isolation were generated at the time of diagnosis and stayed with the person for many months or years. Differing expectations between patient and neurologist following confirmation of diagnosis could contribute to these findings. It is suggested that imparting a diagnosis of MS should be seen as the start of a transition that needs to be made explicit to the patient and closely linked to the provision of sources of information, advice and ongoing support as people learn to live with and manage the disease.

Adaptation, Psychological↗
PubMed2003

Wicking assays for the rapid detection of West Nile and St. Louis encephalitis viral antigens in mosquitoes (Diptera: Culicidae).

The recent outbreaks of West Nile (WN) encephalitis and St. Louis encephalitis (SLE) in the United States have highlighted the need for rapid and specific methods of detecting arboviral antigens in mosquitoes. We evaluated rapid, field-usable assays for detecting and differentiating WN and SLE viruses in mosquito pools, based on a patent-pending, immunochromatographic technology (VecTest) formatted on a dipstick. The device provides results in less than 20 min and can be used in laboratories with adequate containment facilities. In laboratory assessments, both the SLE and WN virus tests demonstrated sensitivity comparable with that of an antigen capture ELISA, but less than can be achieved with Vero cell plaque or reverse-transcriptase polymerase chain reaction assays. There was no evidence of cross-reaction when tested with high concentrations of heterologous flavivirus antigens or with Eastern equine encephalitis or Western equine encephalitis viruses. Both the WN and SLE dipstick tests delivered a clear positive result with a single positive specimen in a pool of 50 mosquitoes. This virus assay technology reduces the time required to obtain test results and will allow rapid medical threat assessment and effective targeting of vector control measures.

Animals↗
PubMed2002

Frequency of p12K and p12R alleles of HTLV Type 1 in HAM/TSP patients and in asymptomatic HTLV type 1 carriers.

HTLV-1 has a complex genome, and contains four open reading frames (ORFs) in the 3' region encoding viral and cellular regulatory proteins. p12 is a small, ORF I-encoded hydrophobic protein, the function of which is not well understood. It has been shown that p12 enhances the E5-transforming ability of bovine papillomavirus; and binds to the 16-kDa subunit of the vacuolar ATPase pump, immature forms of the beta and gamma(c) chains of the interleukin 2 receptor, and the free chain of MHC I. p12 carrying a lysine residue (p12K) at position 88 of its sequence may be rapidly degraded in the cell via proteasome, whereas p12 with an arginine residue (p12R) at the same position is severalfold more stable. These alleles are found in proviral DNA of HTLV-1-infected individuals and it was previously observed that the p12K allele was more frequent in HAM/TSP (HTLV-1-associated myelopathy/tropical spastic paraparesis) patients and was not found at all in asymptomatic carriers, whereas patients with adult T cell leukemia/lymphoma (ATLL) carry the p12R allele. To extend these observations and verify whether the p12K mutation could be used as a marker of progression to HAM/TSP, we analyzed 37 HAM/TSP patients and 40 asymptomatic carriers at different stages of infection. In our cohort, only one HAM/TSP patient carried the p12K phenotype, which accounted for a frequency of 2.7% (1 of 37). We also found, among the 40 asymptomatic HTLV-1 carriers, one who presented the p12K phenotype, contrasting with previous publications. Thus, p12K does not seem to be universally diagnostic for HTLV-1-associated neurological disease. Further screening of HTLV-1-infected individuals in other populations may elucidate this observation.

Adult↗
PubMed2002

An improved assay for genotyping the common Alu insertion in the tissue-type plasminogen activation gene PLAT.

An improved assay for genotyping the common Alu insertion in the tissue-type plasminogen activator (PLAT) locus is described in this report. The assay is a valuable asset to clinical researchers interested in exploring disease associations with this allele. The automation and improved accuracy will facilitate future population-based studies, as well as clinical screening.

Alu Elements↗
PubMed2002

111In-pentetreotide versus bone scintigraphy in the detection of bony metastases of neuroblastoma.

Bone scintigraphy (BS) is widely utilized for the assessment of bone metastases (BMs) of neuroblastoma (NB). Since 111In-pentetreotide scintigraphy (PS) has been used to image NB with high sensitivity, we compared the sensitivity and specificity of PS with that of BS for the detection of BMs of NB. Nine patients with NB underwent both PS and BS for staging and/or restaging of their disease. The sensitivity and specificity of both imaging approaches were compared based on the findings of histopathology, other conventional imaging methods and subsequent clinical follow-up. In five of the nine patients, both PS and BS were negative for BMs. Radiographic bone surveys (RBSs) were also negative in these patients, except in one who showed a suspicious tibial lesion, but a computed tomography-guided biopsy failed to show evidence of disease. These patients remained without clinical evidence of BMs after a median duration of more than 15 months (range, 6-19 months). In three of four remaining patients, both PS and BS were positive for BMs, whilst only PS was positive in one patient. Overall, PS showed a greater number of BMs (30 vs. 7) with greater conspicuity compared with BS. The initial experience comparing BS with PS suggests that PS may provide a better assessment of the extent of BMs of NB, and that it may be useful as an adjunct to BS at institutions in which 131I- or 123I-metaiodobenzylguanidine is not available, particularly if BS is negative. In patients with similarly positive BS, PS might still provide unique prognostic information beyond that provided by BS. Further studies are therefore warranted.

3-Iodobenzylguanidine↗