Biomedical subjects

C D Jones

Publications and source records attributed to C D Jones.

At least 73 records · Page 4Linked to original sources

PubMed2001

Measurement of the relative branching fraction of upsilon(4S) to charged and neutral B-meson pairs.

We analyze 9.7x10(6) B_B pairs recorded with the CLEO detector to determine the production ratio of charged to neutral B-meson pairs produced at the Upsilon(4S) resonance. We measure the rates for B0-->J/psiK((*)0) and B+-->J/psiK((*)+) decays and use the world-average B-meson lifetime ratio to extract the relative widths f(+-) / f(00) = gamma(Upsilon(4S)-->B+B-) / gamma(Upsilon(4S)-->B0 B-0)) = 1.04+/-0.07(stat)+/-0.04(syst). With the assumption that f(+-)+f(00) = 1, we obtain f(00) = 0.49+/-0.02(stat)+/-0.01(syst) and f(+-) = 0.51+/-0.02(stat)+/-0.01(syst). This production ratio and its uncertainty apply to all exclusive B-meson branching fractions measured at the Upsilon(4S) resonance.

Journal Article↗

PubMed2001

Measurement of the lambda(+)(c) lifetime.

The Lambda+c lifetime is measured using 9.0 fb(-1) of e+e- annihilation data collected on or just below the Upsilon(4S) resonance with the CLEO II.V detector at CESR. Using an unbinned maximum likelihood fit, the Lambda+c lifetime is measured to be 179.6+/-6.9(stat)+/-4.4(syst) fs. The precision of this colliding beam measurement is comparable to other measurements, which are based on fixed-target experiments, with different systematic uncertainties.

Journal Article↗

PubMed2001

Ultrasound detection of blunt splenic injury.

The purpose of this study was to determine the sensitivity of emergency ultrasound (US) for the detection of blunt splenic injury (BSI), and to describe sonographic parenchymal patterns. Over 3 years, 2138 emergency US were performed, and 162 patients had BSI. CT was performed for 76 patients, and there were 86 laparotomies. Seventy patients (43%) had concomitant intraabdominal injuries. Ultrasound detected free fluid in 109 patients (67%), and parenchymal injury in 31 patients (19%). There were 48 false negative US (30%). Sonographic patterns included a diffuse heterogeneous appearance, hyperechoic and hypoechoic perisplenic crescents, and discrete hypoechoic or hyperechoic areas within the spleen. Overall sensitivity of US for detection of BSI was 69%, but was 86% for grade III or higher injuries. Ultrasound is most sensitive for the detection of grade III or higher BSI based on the presence of haemoperitoneum. Ultrasound may also identify BSI on the basis of parenchymal abnormality, with a diffuse heterogeneous pattern most commonly encountered. Sonographic evaluation for both free fluid and parenchymal injury improves sensitivity of US.

Adolescent↗

PubMed2001

Functional, dynamic, and anatomic MR urography: feasibility and preliminary findings.

RATIONALE AND OBJECTIVES: The authors assessed the feasibility of using magnetic resonance (MR) urography to acquire functional, dynamic, and anatomic information in human subjects with normal and hydronephrotic kidneys. MATERIALS AND METHODS: In subjects known to have or suspected of having hydronephrosis, split renal filtration fractions were measured with a customized magnetization-prepared, inversion-prepared gradient-recalled echo sequence to determine the T1 of flowing blood in the inferior vena cava and aorta before and after contrast medium administration and in the renal veins and arteries after contrast medium administration. Multiple timed sets of coronal fast spoiled gradient-echo 70 degrees flip-angle images were acquired before and after contrast medium administration to derive MR renograms from changes in the signal intensity of the cortex and medulla. Precontrast T2-weighted images were obtained with a three-dimensional fast spoiled gradient-echo maximum intensity projection pulse sequence, and postcontrast T1 maximum intensity projection images were also obtained to depict the renal anatomy. RESULTS: Split filtration fraction differentiated normal from hydronephrotic kidneys. MR renograms depicted vascular, tubular, and ductal phases and differentiated between normal and hydronephrotic kidneys (P < .05, n = 20). Contrast medium dose correlated with the peak of the cortical signal intensity curves on the renogram (r = 0.7, P < .0005; n = 20). The sensitivities for the visual determination of hydronephrosis and unilateral delayed excretion of contrast material were both 100%, and the specificities were 64% and 85%, respectively. CONCLUSION: The preliminary findings show promise for the use of MR urography in the comprehensive assessment of renal function, dynamics, and anatomy.

Adult↗

PubMed2001

The genetic basis of larval resistance to a host plant toxin in Drosophila sechellia.

The larvae of Drosophila sechellia are highly resistant to octanoic acid, a toxin found in D. sechellia's host plant, Morinda citrifolia. In contrast, close relatives of D. sechellia, D. simulans and D. melanogaster, are not resistant. In a series of interspecific backcrosses, 11 genetic markers were used to map factors affecting egg-to-adult ('larval') resistance in D. sechellia. The third chromosome harbours at least one partially dominant resistance factor. The second chromosome carries at least two mostly dominant resistance factors but no recessive factors. However, neither the X chromosome--which contains 20% of D. sechellia's genome--nor the fourth chromosome appear to affect resistance. These data suggest that larval resistance to Morinda toxin may involve only a handful of genes. These results, when compared with a previous analysis of adult resistance to Morinda toxin in D. sechellia, suggest that larval resistance may involve a subset of the genes underlying adult resistance.

Animals↗

PubMed2001

A novel, recombinant triple antigen hepatitis B vaccine (Hepacare).

Infection with hepatitis B virus (HBV) continues to be a major problem in the human population. There remains a specific requirement for HBV vaccines capable of circumventing the non-responder/inadequate responder status of some vaccinees. Hepacare has been primarily developed to (1) improve anti-SHBs antibody titres in low responders, to conventional SHBsAg vaccinees, (2) overcome difficulties of non-compliance seen with existing SHBsAg vaccine regimens. Hepacare is a novel recombinant particle produced in eukaryotic cells, consisting of pre-S1, pre-S2 and S proteins of HBV and is adjuvanted with alhydrogel. It has been demonstrated to be highly immunogenic for both B and T cells in mice, chimpanzees and humans and induces higher anti-S 'a' determinant antibody titres than SHBsAg vaccines in mice and humans. Hepacare has proven to be at least as efficacious as current SHBsAg vaccines in chimpanzees. Clinical trials in both Europe and the USA have clearly demonstrated its superior ability to induce anti-SHBs antibody seroconversion in low-responder groups, compared with SHBsAg vaccines.

Animals↗

PubMed2001

Ultrasonographic evaluation of diaphragmatic motion.

OBJECTIVE: To evaluate the technical feasibility and utility of ultrasonography in the study of diaphragmatic motion at our institution. METHODS: The study consisted of 2 parts. For part I, in 23 volunteers we performed 23 studies on 46 hemidiaphragms with excursions documented on M-mode ultrasonography For part II, in 22 patients we performed 52 studies in 102 hemidiaphragms. In 50 studies both hemidiaphragms were studied, and in another 2 studies only 1 hemidiaphragm was studied. Patients' ages ranged from birth to 66 years (mean, 23 years). There were 16 male and 6 female patients. Indications for the study were (1) suggestion of paralysis of the diaphragm (n = 22); (2) if the diaphragm was already known to be paralyzed, for evaluation of response to phrenic nerve or pacer stimulation (n = 9); and (3) follow-up of previous findings (n = 21). Patients were examined in the supine position in the longitudinal semicoronal plane from a subcostal or low intercostal approach. Motion was documented with real-time ultrasonography and measured with M-mode ultrasonography. RESULTS: Of the 102 clinical hemidiaphragms studied, findings included normal motion (n = 42), decreased motion (n = 22), no motion (n = 6), paradoxical motion (n = 10), positive pacer response (n = 13), negative pacer response (n = 2), positive phrenic stimulation (n = 6), and negative phrenic stimulation (n = 1). There were no failures of visualization. CONCLUSIONS: Ultrasonography proved feasible and useful in evaluating diaphragmatic motion. In our practice it has replaced fluoroscopy. Ultrasonography has advantages over traditional fluoroscopy, including portability, lack of ionizing radiation, visualization of structures of the thoracic bases and upper abdomen, and the ability to quantify diaphragmatic motion.

Adolescent↗

PubMed2000

Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model.

The continued increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being absorbed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO2 concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon-climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a 'business as usual' scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C yr(-1) is balanced by the terrestrial carbon source, and atmospheric CO2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback.

Journal Article↗

PubMed2000

Study of charmless hadronic B meson decays to pseudoscalar-vector final states.

We report results of searches for charmless hadronic B meson decays to pseudoscalar( pi(+/-), K+/-, pi(0), or K(0)(S))-vector( rho, K(*), or omega) final states. By using 9.7x10(6) BB pairs collected with the CLEO detector, we report the first observation of B(-)--->pi(-)rho(0), B(0)-->pi(+/-)rho(-/+), and B(-)-->pi(-)omega, which are expected to be dominated by hadronic b-->u transitions. The measured branching fractions are (10.4(+3.3)(-3.4)+/-2.1)x10(-6), (27.6(+8.4)(-7.4)+/-4.2)x10(-6), and (11.3(+3.3)(-2.9)+/-1. 4)x10(-6), respectively. Branching fraction upper limits are set for all of the other decay modes investigated.

Journal Article↗

PubMed2000

Search for CP violation in B+/- --> J/psiK+/- and B+/- --> psi(2S)K+/- decays.

We present a search for direct CP violation in B+/--->J/psiK+/- and B+/--->psi(2S)K+/- decays. In a sample of 9.7x10(6) B&Bmacr; meson pairs collected with the CLEO detector, we have fully reconstructed 534 B+/--->J/psiK+/- and 120 B+/--->psi(2S)K+/- decays with very low background. We have measured the CP-violating charge asymmetry to be [+1.8+/-4.3(stat)+/-0.4(syst)]% for B+/--->J/psiK+/- and [+2.0+/-9. 1(stat)+/-1.0(syst)]% for B+/--->psi(2S)K+/-.

Journal Article↗

PubMed2000

Detecting the undetected: estimating the total number of loci underlying a quantitative trait.

Recent studies have begun to reveal the genes underlying quantitative trait differences between closely related populations. Not all quantitative trait loci (QTL) are, however, equally likely to be detected. QTL studies involve a limited number of crosses, individuals, and genetic markers and, as a result, often have little power to detect genetic factors of small to moderate effects. In this article, we develop an estimator for the total number of fixed genetic differences between two parental lines. Like the Castle-Wright estimator, which is based on the observed segregation variance in classical crossbreeding experiments, our QTL-based estimator requires that a distribution be specified for the expected effect sizes of the underlying loci. We use this expected distribution and the observed mean and minimum effect size of the detected QTL in a likelihood model to estimate the total number of loci underlying the trait difference. We then test the QTL-based estimator and the Castle-Wright estimator in Monte Carlo simulations. When the assumptions of the simulations match those of the model, both estimators perform well on average. The 95% confidence limits of the Castle-Wright estimator, however, often excluded the true number of underlying loci, while the confidence limits for the QTL-based estimator typically included the true value approximately 95% of the time. Furthermore, we found that the QTL-based estimator was less sensitive to dominance and to allelic effects of opposite sign than the Castle-Wright estimator. We therefore suggest that the QTL-based estimator be used to assess how many loci may have been missed in QTL studies.

Algorithms↗

PubMed2000

PCR-heteroduplex analysis of T-cell receptor gamma gene rearrangement in paraffin-embedded skin biopsies.

We developed a rapid, simple, and sensitive method for the detection of T-cell receptor-gamma (TCRgamma) gene rearrangements in paraffin-embedded skin biopsies. Available techniques often require either fresh tissue, several primer pairs, nested amplifications, or specialized electrophoresis steps such as denaturing gradient gel electrophoresis. Our method is based on heteroduplex analysis of polymerase chain reaction (PCR) products of the TCRgamma in a nondenaturing modified polyacrylamide gel using a single pair of primers and is adapted for paraffin-embedded tissue. When tested against Southern blot analysis, the PCR results correlated in 8 of 9 cases. Six mature cutaneous B-cell lymphomas and 29 inflammatory skin disorders all resulted in a polyclonal amplification pattern. When analyzing 3-mm or 4-mm punch biopsies of 51 cases of cutaneous T-cell lymphoma, 37 (72.5%) showed a clonal rearrangement with this technique. For 7 cases of patch stage mycosis fungoides, frozen tissue and formalin-fixed and paraffin-embedded tissue was available, and in 5 of 7 cases (71%), the results in frozen and paraffin-embedded tissue were concordant. One case showed a clonal pattern in frozen tissue but not in paraffin-embedded tissue, and one case was polyclonal in frozen tissue but monoclonal in paraffin-embedded tissue. Using serial dilutions of DNA from a T-cell ALL in a polyclonal background (tonsil), we established a sensitivity of 0.5%. Heteroduplex PCR of the TCRgamma is a rapid, sensitive, and inexpensive screening procedure as well as a useful adjunct to histologic analysis and immunophenotyping of cutaneous T-cell proliferations.

Biopsy, Needle↗

PubMed2000

Blastic/blastoid transformation of follicular lymphoma: immunohistologic and molecular analyses of five cases.

Progression of follicular lymphoma to a higher-grade malignancy frequently heralds a poor prognosis. Clinical transformation is variably accompanied by a spectrum of histologic changes characterized by alteration in growth and cytology. Although several cytogenetic events and potential oncogenes have been documented in this progression, the underlying molecular mechanisms are largely unknown. We present five patients with an unusual histologic transformation of follicular lymphoma manifested by blastic/blastoid morphology. This transformation is histologically distinct from other types of transformation of follicular lymphoma. All five cases exhibited the t(14;18) translocation and expressed the BCL-2 protein. In addition, two of the five patients showed increased levels of the p53 protein within neoplastic cells implicating a possible role for this oncogene in blastic/blastoid transformation. The lack of BCL-1 and myeloid antigens by immunohistochemistry and flow cytometry studies served to distinguish blastic/blastoid transformation of follicular lymphoma from its morphologic mimics. This distinction is clinically important because lymphoblastic and myeloid leukemias require significantly different therapeutic modalities and show better prognosis. Moreover, the lack of Epstein-Barr virus-specific mRNA suggests that this virus is unlikely to participate in blastic/blastoid transformation of follicular lymphoma.

Adult↗

PubMed2000

Sensitive detection of clonal immunoglobulin rearrangements in frozen and paraffin embedded tissues by polymerase chain reaction heteroduplex analysis.

Molecular detection of a clonal population of B or T cells through analysis of rearranged antigen receptor genes is an essential adjunct to the morphologic, flow cytometric, and immunohistochemical evaluation of tissue specimens for the presence of leukemia or lymphoma. Combining polymerase chain reaction (PCR) with heteroduplex annealing and polyacrylamide gel electrophoresis (PAGE) has been used to detect clonal T-cell receptor rearrangements, particularly in skin biopsy specimens. The authors have developed a similar PCR heteroduplex assay for detection of clonal VDJ immunoglobulin gene rearrangements using two sets of primers based on relatively conserved consensus regions in the J(H) and framework I and 2 regions of the immunoglobulin heavy chain V region gene. This method is able to detect a clonal rearrangement when the clone comprises as little as 1% of the population in a polyclonal B-cell background. It may be used on fresh, frozen, or paraffin-embedded tissue and detects a clonal population in a majority of lymphoma subtypes. Compared with conventional PCR analysis, this method requires only a short additional cycle of denaturation and slow renaturation before PAGE. Interpretation is simplified as the clonal PCR product migrates away from the polyclonal background products.

Antibodies, Monoclonal↗

PubMed2000

Comparison of US utilization and technical costs before and after establishment of 24-hour in-house coverage for US examinations.

PURPOSE: To compare data regarding the cost and number of ultrasonographic (US) examinations performed for 6 months, before and after institution of 24-hour in-house sonographer coverage. MATERIALS AND METHODS: Data for a 6-month period during which US services were provided by a sonographer on call from 11 PM to 7 AM were compared with data for a 6-month period during which a sonographer was in house during this shift. RESULTS: With 11 PM to 7 AM on-call coverage, the sonographers performed 147 examinations in a 6-month period, an average of 0.81 examination per shift. After institution of in-house coverage for this shift, 792 US examinations were performed in 6 months, an average of 4.3 examinations per shift. The cost for 11 PM to 7 AM in-house sonographer coverage for 6 months was approximately $16,000 more than that for on-call coverage. This cost would be offset by revenues from one additional examination per night. The cost per examination for the 11 PM to 7 AM shift decreased from $124.70 to $43.33. CONCLUSION: At the authors' institution, 24-hour in-house sonographer coverage resulted in additional cost, which was offset by revenues from additional examinations. There was nearly a fivefold increase in the number of US examinations performed per shift. These examinations were performed more expediently, enabling more rapid patient triage.

California↗

PubMed2000

Radio-frequency electrocautery ablation of mammary tissue in swine.

PURPOSE: To establish the size, configuration, and histopathologic features of acute, subacute, and chronic radio-frequency (RF) electrocautery of mammary tissue in swine. MATERIALS AND METHODS: Eighteen RF treatments were performed in the mammary tissue of three domestic swine under ultrasonographic (US) guidance. Histopathologic examination was performed immediately after (acute animal); 2 weeks after (subacute animal); and 4 weeks after (chronic animal) treatment. RESULTS: In the acute animal, lesions were firm nodules on palpation and had a distinct line of demarcation between necrotic and viable mammary tissue (mean lesion volume, 14.24 cm(3); largest volume, 29.06 cm(3)). In the subacute animal, there was diffuse coagulation necrosis with neutrophilic infiltrates at the periphery (mean lesion volume, 6.46 cm(3); largest volume, 9.47 cm(3)), and two treatment areas had a secondary bacterial infection. In the chronic animal, lesions were still palpable and firm (mean lesion volume, 11.67 cm(3); largest volume, 25.5 cm(3)), and five of six treatment sites had an area of gray to white fibrotic tissue that blended with the surrounding tissue. However, one site had a pale yellow area of central necrosis surrounded by a fibrotic area. In both the subacute and chronic animals, two and one treatment site, respectively, had minimal areas of skin necrosis. CONCLUSION: RF ablation of breast tissue is feasible in this animal model. Problems included minimal skin erythema, residual firm treatment regions at 4 weeks, slightly variable margins of coagulation necrosis, and occasional bacterial infection.

Animals↗

PubMed2000

Peripheral T-cell lymphoma complicated by a proliferation of large B cells.

We studied 14 cases that showed a morphologic appearance of peripheral T-cell lymphoma and contained substantial numbers of CD20+ large B cells. In all but 2 cases, the CD20+ large cells showed a mix of kappa and lambda light chain expression. Two cases showed a focal predominance of kappa expression. In situ hybridization using the EBER1 probe for detection of Epstein-Barr virus (EBV) RNA was performed on every case. EBV RNA was present in 10 cases. Of 8 cases with EBV RNA stained by immunohistochemistry for the latent membrane protein of EBV, 6 were positive. Double-labeling immunohistochemistry and in situ hybridization confirmed that EBV was present in the large B cells. Polymerase chain reaction (PCR) analysis showed a clonal rearrangement of the T-cell receptor (TCR)-gamma chain gene in 12 of 13 cases tested. One additional case showed a clonal rearrangement of the TCR-beta chain gene by Southern blot hybridization. PCR analysis showed a clonal immunoglobulin gene rearrangement in 5 cases, a suggestion of a clonal rearrangement in 1, an oligoclonal pattern in 4, and a polyclonal pattern in 4. The finding of large B and T cells may result in a misdiagnosis of a reactive process or of T-cell-rich B-cell lymphoma. The presence of EBV in some cases could cause further confusion with the reactive T- and B-immunoblastic proliferation of infectious mononucleosis.

Adult↗

PubMed2000

Comparison of PCR detection methods for B1, P30, and 18S rDNA genes of T. gondii in aqueous humor.

PURPOSE: Comparison of polymerase chain reaction (PCR) amplification of three Toxoplasma gondii genes in aqueous humor. METHODS: Nested PCRs carried out using published methods were optimized for maximum sensitivity and specificity. Five pairs of oligonucleotide primers, directed against the B1, P30, and ribosomal genes, were used and compared to determine which sequences were most effective in detecting T. gondii DNA. Methods were developed with DNA templates in water and were subsequently applied to both normal and inflamed aqueous. RESULTS: After one round of PCR amplification, P30 and ribosomal primers were able to detect 1 pg genomic T. gondii DNA. However, those directed against the B1 gene were able to detect 50 fg (approximately single tachyzoite). This level of sensitivity was also achieved using the P30 primers after a second round of PCR; however, only primers based on the B1 gene maintained this level of sensitivity in both normal and inflamed aqueous. B1-specific primers did not amplify sequences from fungal, bacterial, or human lymphocyte DNA. The sensitivity of T. gondii detection using B1 gene-specific primers was not compromised when large amounts of human lymphocyte DNA were present, and application to an ocular sample or retinal section from patients with toxoplasma chorioretinitis was successful in confirming the presence of T. gondii DNA. CONCLUSIONS: The B1 PCR protocol appears to be the most sensitive protocol in the detection of T. gondii DNA and has been successful in identification of T. gondii DNA in ocular fluids and retinal sections. This provides direct evidence of the presence of T. gondii within the eye and may therefore help in the management of toxoplasma retinochoroiditis.

Animals↗