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Biomedical subjects

C Brown

Publications and source records attributed to C Brown.

At least 55 records · Page 3Linked to original sources

Once-daily intravenous busulfan given with fludarabine as conditioning for allogeneic stem cell transplantation: study of pharmacokinetics and early clinical outcomes.

The availability of an i.v. form of busulfan (Bu) has prompted investigation of administration schedules other than the 4-times-daily dosage commonly used with oral Bu. We have studied an allogeneic stem cell transplantation (SCT) preparative regimen comprising fludarabine (FLU) 50 mg/m2 on days -6 to -2 plus i.v. Bu 3.2 mg/kg daily in a 3-hour infusion on days -5 to -2. The regimen was given to 70 patients aged 15 to 64 years (median, 41 years) with hematologic malignancy. Thirty-six patients (51%) had high-risk malignancy, 28 (40%) had unrelated or genotypically mismatched related donors (alternate donors [AD]) and 29 (41%) received bone marrow rather than blood as stem cell source. Acute GVHD prevention comprised antithymocyte globulin 4.5 mg/kg over 3 days pretransplantation, cyclosporin A, and short-course methotrexate with folinic acid. Hepatic toxicity was transient and there was no clinically diagnosed veno-occlusive disease. Grade II stomatitis occurred in 49 patients (70%) and hemorrhagic cystitis in 9 patients (13%). One patient with subtherapeutic phenytoin levels had a convulsion 8 hours after the third i.v. Bu dose, but no other neurotoxicity was apparent. Incidence of acute GVHD grades II to IV was 8% and incidence of grade III-IV was 3%, with no deaths from this cause. Actuarial incidence of chronic GVHD at 2 years is 38%. There were 2 cases of graft failure in unrelated donor BMT recipients, 1 of which was reversed by asecond transplantation. With a median follow-up of 16 months (range, 6-27 months), transplantation-related mortality at 100 days and 2 years was 2% and 5% for matched related donor (MRD) SCT and 8% and 19% for AD SCT, respectively (P = not significant). Relapse rates were 21% for 34 patients with acute myeloid leukemia (AML) in complete remission or chronic myeloid leukemia in chronic phase (low-risk), 66% for 19 patients with high-risk AML, and 18% for 17 patients with other active malignancy. Projected disease-free and overall survival rates at 2 years were 74% and 88% for low-risk disease, 26% and 37% for advanced AML, and 65% and 71% for other high-risk disease, respectively. Pharmacokinetic studies were done using 11 samples with the first and fourth doses of Bu. Kinetics were linear, and for the first and fourth doses, the half-lives were 2.60 +/- 0.44 and 2.57 +/- 0.36 hours, respectively. Clearances were 106.77 +/- 16.68 and 106.86 +/- 21.57 mL/min per m2, peak concentrations (Cmax) were 3.92 +/- 0.31 and 3.96 +/- 0.28 mcg/mL, and Bu areas under the plasma concentration versus time curve (AUC) were 4866.51 +/- 771.42 and 4980 +/- 882.80 microM x min, respectively. Bu was completely cleared within 24 hours and the day 4 pharmacokinetic values were very similar to those on day 1 for every patient. The cumulative AUC was comparable to the target range established for p.o. Bu. This regimen incorporating once-daily i.v. Bu is convenient to give, is relatively well tolerated, gives predictable blood levels, and deserves further study in circumstances in which cytoreduction as well as immune suppression is needed.

Adolescent↗

Major histocompatibility complex susceptibility genes and immune thrombocytopenic purpura in Caucasian adults.

Immune thrombocytopenic purpura (ITP) is a heterogeneous disorder with wide variability in response rates to treatments including corticosteroids, splenectomy and intravenous immune globulins. The nature of the underlying predisposing causes for this autoimmune disorder are not known. We have HLA typed 71 adult Caucasian patients with chronic primary ITP, and compared the data with 750 control samples. In this association study, we were not able to identify a significant immunogenetic susceptibility factor for ITP with HLA class I and class II alleles. However, it appeared that there might be an association between HLA-A2 and ITP, particularly in female patients, who are the predominantly affected group; and HLA-A2 was also present at increased frequency in patients with chronic ITP progressing to splenectomy. These findings are reviewed in the context of other similar reported HLA studies in ITP. Further studies based on larger groups of patients will be necessary to identify genetic susceptibility factors for this disease.

Case-Control Studies↗

Reactivity and isotype profiling of monoclonal antibodies using multiple antigenic peptides.

The characterisation of monoclonal antibodies (MAbs) is essential for the development of assay systems particularly where antigens have been developed using synthetic peptides. Indeed some peptide-carrier conjugates fail to induce immune responses and may not generate antibodies that bind to native protein. As an alternative to peptide-carrier conjugates, multiple antigenic peptides (MAPs) have been used for immunization strategies, but with little regard to the characteristics of the MAbs produced. In this study, we used 3 MAPs of Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) to immunise BALB/c mice. Overall, the polyclonal antibody responses from tail bleeds showed that MAPs evoked B-cell responses. However, on screening 144 hybridomas, 24 MAb supernatants exhibited weak to moderate reactivity in enzyme-linked immunosorbant assay (ELISA) and against cell cytospin preparations (B95.8 and AG876 LCL), respectively. Isotype profiling of hybridoma supernatants also showed that 11 out of 24 were IgM. Further characterization of 6 MAbs in Western blotting showed reactivity to recombinant LMP1 and only one MAb (B28D) showed weak reactivity to the malignant cells (Hodgkin/Reed-Sternberg; HRS cells) of an EBV+ Hodgkin's lymphoma using paraffin-embedded tissue. It is probable that these MAPs failed to augment T-cell help and contributed to the production of low affinity (IgM) antibodies. These observations may be of importance to future immunization strategies, where MAPs are used in the production of monoclonal reagents.

Animals↗

Localization of astrovirus in experimentally infected turkeys as determined by in situ hybridization.

Twenty-one 3-day-old turkey poults from British United Turkeys of America were orally inoculated with a recently characterized astrovirus, TAstV-2, isolated from turkeys with poult enteritis and mortality syndrome. At 1, 2, 3, 4, 5, 7, and 9 days postinfection (dpi), three inoculated birds were euthanatized, and tissues (intestines, spleen, bursa, and thymus) were collected immediately into 10% neutral buffered formalin. Inoculated birds were diarrheic by 3 dpi, and frothy feces persisted throughout the experimental period. Histologically, there was only slight evidence of enteric damage, which was characterized by mild epithelial necrosis, lamina propria infiltrates, minimal villus atrophy, and mild crypt hyperplasia. In situ hybridization, using a negative sense digoxigenin-labeled riboprobe to the capsid gene of TAstV-2, revealed viral RNA in intestinal epithelial cells at the basal margins of the villi, in distal small intestine, and in cecum at 2 dpi, with subsequent extension to epithelium of the large intestine and proximal small intestine (3-5 dpi). Minimal virus remained by 9 dpi.

Animals↗

Economic costs of the foot and mouth disease outbreak in the United Kingdom in 2001.

The authors present estimates of the economic costs to agriculture and industries affected by tourism of the outbreak of foot and mouth disease (FMD) in the United Kingdom (UK) in 2001. The losses to agriculture and the food chain amount to about Pound Sterling3.1 billion. The majority of the costs to agriculture have been met by the Government through compensation for slaughter and disposal as well as clean-up costs. Nonetheless, agricultural producers will have suffered losses, estimated at Pound Sterling355 million, which represents about 20% of the estimated total income from farming in 2001. Based on data from surveys of tourism, businesses directly affected by tourist expenditure are estimated to have lost a similar total amount (between Pound Sterling2.7 and Pound Sterling3.2 billion) as a result of reduced numbers of people visiting the countryside. The industries which supply agriculture, the food industries and tourist-related businesses will also have suffered losses. However, the overall costs to the UK economy are substantially less than the sum of these components, as much of the expenditure by tourists was not lost, but merely displaced to other sectors of the economy. Overall, the net effect of FMD is estimated to have reduced the gross domestic product in the UK by less than 0.2% in 2001.

Agriculture↗

Rotavirus vaccine and intussusception: how much risk will parents in the United States accept to obtain vaccine benefits?

Postlicensure surveillance of a newly licensed rotavirus vaccine suggested an increased risk of intussusception. Little was known about the amount of risk parents would tolerate to obtain the vaccine's benefits or the extent to which risk would reduce the price parents would pay for the vaccine. Parents of infants aged 12 months or younger were asked to accept or reject two hypothetical vaccines associated with varying degrees of risk. Parents chose from a list the amount they would pay for two additional hypothetical vaccines, with and without a risk of intussuception. The authors conducted face-to-face surveys in September 1999 among a convenience sample of parents in three US cities. Of 405 eligible parents, 260 (64%) participated. To achieve a 90% acceptance rate, the vaccine could be associated with no more than 1,794 (95% confidence interval: 1,551, 2,025) cases of intussusception in a fully vaccinated, national cohort of infants. The median willingness to pay for three vaccine doses, when vaccination was associated with 1,400 cases of intussusception, was $36 (95% confidence interval: $28, $46) compared with $110 (95% confidence interval: $96, $126) for the risk-free vaccine. The most important aspect of this study may be the methodology to assess how parents balance the benefits and risks of childhood vaccines.

Adult↗

Structural and oxo-transfer reactivity differences of hexacoordinate and pentacoordinate (nitro)(tetraphenylporphinato)cobalt(III) derivatives.

The oxo-transfer catalyst (nitro)(pyridyl)cobalt(III) tetraphenylporphyrin has been reinvestigated by substitution of the distal pyridine ligand with 4-N,N-dimethylaminopyridine and 3,5-dichloropyridine. Differences in their structures and in the reactivity of the compounds toward catalytic secondary oxo transfer were investigated by FT-IR and UV-visible spectroscopy, cyclic voltammetry, X-ray diffraction, semiempirical calculations, and reactions with alkenes in dichloromethane solution. Very modest differences in the hexacoordinate compounds' structures were predicted and observed, but the secondary oxo-transfer reactivity at the nitro ligand varies markedly with the basicity of the pyridine ligand and the position of the coordination equilibrium. Oxo transfer occurs rapidly through the pentacoordinate species (nitro)cobalt(III) tetraphenylporphyrin that is generated by dissociation of the pyridine ligand and therefore is strongly related to the Hammett parameters of these nitrogenous bases. The reactive pentacoordinate species CoTPP(NO(2)) can be generated in solution by addition of lithium perchlorate to (py)CoTPP(NO(2)) by Lewis acid-base interactions or more simply by using the weaker Lewis base Cl(2)py instead of py as the distal ligand. In contrast to pentacoordinate (nitro)iron porphyrins, disproportionation reactions of CoTPP(NO(2)) compound are not evident. This pentacoordinate derivative, CoTPP(NO(2)), is reactive enough to stoichiometrically oxidize allyl bromide in minutes. Preliminary catalytic oxidation reaction studies of alkenes also indicate the involvement of both radical and nonradical oxo-transfer steps in the mechanism, suggesting formation of a peroxynitro intermediate in the reaction of the reduced CoTPP(NO) with O(2).

Journal Article↗

Septic shock due to babesiosis.

We present the case of a 69-year-old man with an unremarkable past medical history and an intact spleen who developed shock and renal failure due to babesiosis. Despite hemodynamic parameters showing severe distributive shock with hyperdynamic cardiac function, the patient recovered fully after treatment with quinine sulfate and clindamycin.

Acute Kidney Injury↗

Diagnosis, pathology, staging, treatment, and outcome of epithelial ovarian neoplasia in patients age < 21 years.

BACKGROUND: Epithelial ovarian neoplasms are rare in patients under the age of 21 years. This is a report of a series of such patients documenting their presentation, histologic type, stage of disease, treatment, and outcome. METHODS: Clinical findings, histology, stage, treatment, and outcomes of 19 patients with epithelial ovarian neoplasia are reported. All histology was rereviewed. RESULTS: The median age at the time of diagnosis was 19.7 years (range, 14.1-21.8 years), and the median follow-up was 5.6 years (range, 0.2-19.5 years). The most common presenting symptom was dysmenorrhea (100%) followed by abdominal pain (68%), and the initial diagnosis usually was made ultrasonographically. There were nine (47%) serous tumors, 7 (37%) mucinous tumors, 2 (11%) small cell carcinomas, and 1 (5%) endometrioid carcinoma. Seventy-nine percent of tumors were unilateral, and 84% were low malignant potential or well differentiated tumors. Surgical treatment included unilateral salpingo-oophorectomy in 12 patients (63%), total abdominal hysterectomy and bilateral salpingo-oophorectomy in 6 patients (32%), and ovarian cystectomy in 1 patient (5%). Fifteen patients (79%) had Stage I disease, and 4 patients (21%) had Stage III disease at the time of diagnosis. There were two deaths in this series, and both occurred in patients with small cell anaplastic carcinoma. CONCLUSIONS: Epithelial ovarian neoplasias are rare in patients in this age group but must be included in the differential diagnosis of an ovarian mass. Most patients present with Stage I tumors of low malignant potential. In these patients, good survival is achieved with unilateral salpingo-oophorectomy and preservation of fertility. In contrast, small cell carcinomas are very aggressive, and patients with this variant require intensive therapy.

Abdominal Pain↗

Normal personality traits and comorbidity among phobic, panic and major depressive disorders.

High comorbidity among anxiety and depressive conditions is a consistent but not well-understood finding. The current study examines how normal personality traits relate to this comorbidity. In the Baltimore Epidemiologic Catchment Area Follow-up Study, psychiatrists administered the full Schedules for Clinical Assessment in Neuropsychiatry to 320 subjects, all of whom completed the Revised NEO Personality Inventory. The disorders of interest were simple phobia, social phobia, agoraphobia, panic disorder, and major depression. Analyses were carried out with second-order generalized estimating equations. The unadjusted summary odds ratio (SOR - or weighted mean odds ratio) for all five disorders was 1.72 (95% confidence interval=1.21-2.46). Neuroticism, introversion, younger age, and female gender were all significant predictors of prevalence of disorders. After adjustment for the relationships between these personality and demographic predictors and prevalence, the association among disorders was much weaker (SOR=1.11, 95% CI=0.79-1.56). However, subjects with high extraversion had a SOR 213% as high (95% CI=102-444%) as those with low extraversion (1.60 vs. 0.75). Therefore, neuroticism and introversion are associated with increased comorbidity due to relationships in common with the prevalence of the different disorders. In contrast, extraversion is associated with increased comorbidity per se.

Major Depressive Disorder↗

Management of acute exacerbations of chronic obstructive pulmonary disease: a summary and appraisal of published evidence.

PURPOSE: To review critically the available data on diagnostic evaluation, risk stratification, and therapeutic management of patients with acute exacerbations of chronic obstructive pulmonary disease (COPD). DATA SOURCES: English-language articles were identified by searching MEDLINE (1966 to 2000, week 5), EMBASE (1974 to 2000, week 18), HealthStar (1975 to June 2000), and the Cochrane Controlled Trials Register (2000, Issue 1). STUDY SELECTION: The best available evidence on each subtopic was selected for analysis. Randomized trials, sometimes buttressed by cohort studies, were used to evaluate therapeutic interventions. Cohort studies were used to evaluate diagnostic tests and risk stratification. DATA EXTRACTION: Study design and results were summarized in evidence tables. Individual studies were rated by internal validity, external validity, and quality of design. Statistical analyses of combined data were not performed. DATA SYNTHESIS: Data on the utility of most diagnostic tests are limited. However, chest radiography and arterial blood gas sampling seem useful while acute spirometry does not. Identifiable clinical variables are associated with risk for relapse and risk for death after hospitalization for an acute exacerbation. Evidence of efficacy was found for bronchodilators, corticosteroids, and noninvasive positive-pressure ventilation. There is also support for the use of antibiotics in patients with more severe exacerbations. On the basis of limited data, mucolytics and chest physiotherapy do not seem to be of benefit, and oxygen supplementation seems to increase the risk for respiratory failure only in an identifiable subgroup of patients. CONCLUSIONS: Although suggestions for appropriate management can be made on the basis of available evidence, the supporting literature is scarce and further high-quality research is necessary. Such research will require an improved, generally acceptable, and transportable definition of acute exacerbation of COPD, as well as improved methods for observing and measuring outcomes.

Acute Disease↗

Erythroid Kruppel-like factor (EKLF) coordinates erythroid cell proliferation and hemoglobinization in cell lines derived from EKLF null mice.

Erythroid Kruppel-like factor (EKLF) is a transcription factor of the C2H2 zinc-finger class that is essential for definitive erythropoiesis. We generated immortal erythroid cell lines from EKLF(-/-) fetal liver progenitor cells that harbor a single copy of the entire human beta-globin locus and then reintroduced EKLF as a tamoxifen-inducible, EKLF-mutant estrogen receptor (EKLF-ER) fusion protein. Addition of tamoxifen resulted in enhanced differentiation and hemoglobinization, coupled with reduced proliferation. Human beta-globin gene expression increased significantly, whereas gamma-globin transcripts remained elevated at levels close to endogenous mouse alpha-globin transcript levels. We conclude that EKLF plays a role in regulation of the cell cycle and hemoglobinization in addition to its role in beta-globin gene expression. The cell lines we used will facilitate structural and functional analyses of EKLF in these processes and provide useful tools for the elucidation of nonglobin EKLF target genes.

Active Transport, Cell Nucleus↗

Emergence of Salmonella enteritidis phage type 4 in the Caribbean: case-control study in Trinidad and Tobago, West Indies.

A prospective case-control study involving 46 case patients and 92 age- and neighborhood-matched control subjects was conducted in Trinidad and Tobago (T&T) between March 1998 and May 1999 to determine the etiology, sources, and risk factors for Salmonella enteritidis (SE) infection. SE infection in T&T was found to be associated with the consumption of shell eggs, and in particular raw or undercooked eggs. SE isolates from 30 (88%) of 34 patients and from 9 implicated egg or egg-containing food samples were phage type 4. Homemade eggnog and ice cream, cake batter, and egg-containing beverages were the main raw egg-containing foods, reflecting the cultural practices of the people of T&T. Public health education on the risks of eating raw or undercooked eggs, thorough cooking of all egg dishes, and refrigeration of shell eggs and egg dishes; studies tracing infected eggs to their sources; and testing of flocks of layer chickens for SE are needed to reduce the incidence of this infection.

Adolescent↗

Membrane-perturbing domains of HIV type 1 glycoprotein 41.

Structural and functional studies were performed to assess the membrane actions of peptides based on HIV-1 glycoprotein 41,000 (gp41). Previous site-directed mutagenesis of gp41 has shown that amino acid changes in either the N-terminal fusion or N-leucine zipper region depressed viral infection and syncytium formation, while modifications in the C-leucine zipper domain both increased and decreased HIV fusion. Here, synthetic peptides were prepared corresponding to the N-terminal fusion region (FP-I; gp41 residues 519-541), the nearby N-leucine zipper domain (DP-107; gp41 residues 560-597), and the C-leucine zipper domain (DP-178; gp41 residues 645-680). With erythrocytes, FP-I or DP-107 induced dose-dependent hemolysis and promoted cell aggregation; FP-I was more hemolytic than DP-107, but each was equally effective in aggregating cells. DP-178 produced neither hemolysis nor aggregation, but blocked either FP-I- or DP-107-induced hemolysis and aggregation. Combined with previous nuclear magnetic resonance and Fourier transform infrared spectroscopic results, circular dichroism (CD) spectroscopy showed that the alpha-helicity for these peptides in solution decreased in the order: DP-107 >> DP-178 > FP-I. CD analysis also indicated binding of DP-178 to either DP-107 or FP-I. Consequently, DP-178 may inhibit the membrane actions mediated by either FP-I or DP-107 through direct peptide interactions in solution. These peptide results suggest that the corresponding N-terminal fusion and N-leucine zipper regions participate in HIV infection, by promoting membrane perturbations underlying the merging of the viral envelope with the cell surface. Further, the C-leucine zipper domain in "prefusion" HIV may inhibit these membrane activities by interacting with the N-terminal fusion and N-leucine zipper domains in unactivated gp41. Last, exogenous DP-178 may bind to the N-terminal and N-leucine zipper domains of gp41 that become exposed on HIV stimulation, thereby preventing the fusogenic actions of these gp41 regions leading to infection.

Amino Acid Sequence↗

Fast ignition by intense laser-accelerated proton beams.

The concept of fast ignition with inertial confinement fusion (ICF) is a way to reduce the energy required for ignition and burn and to maximize the gain produced by a single implosion. Based on recent experimental findings at the PETAWATT laser at Lawrence Livermore National Laboratory, an intense proton beam to achieve fast ignition is proposed. It is produced by direct laser acceleration and focused onto the pellet from the rear side of an irradiated target and can be integrated into a hohlraum for indirect drive ICF.

Journal Article↗

Early prediction of 30-day mortality after Q-wave myocardial infarction by echocardiographic assessment of left ventricular function--a pilot investigation.

BACKGROUND: The GUSTO angiographic substudy demonstrated that left ventricular function measured 90 min after thrombolytic therapy was given had important prognostic implications at 30 days in patients with an acute myocardial infarction (MI). HYPOTHESIS: Thirty-day prognosis after Q-wave MI can be determined by early echocardiographic assessment of left ventricular function. METHODS: Using transthoracic echocardiography, semiquantitative ejection fraction and wall motion score index was assessed prospectively in 201 consecutive patients within 24 h following Q-wave MI. Independent experts blinded to the patient's status performed the echocardiographic assessment. All patients received standard medical care as dictated by the attending cardiologist. RESULTS: Of the 201 patients, 24 (11.9%) died within 30 days, with 70% of the deaths occurring within 10 days after the infarction. Three deaths occurred in the 120 patients with an ejection fraction > or = 45% (2.5% mortality rate). In contrast, 21 deaths occurred among the 81 patients with an ejection fraction <45% (25.9% mortality rate) p = 0.0003. Two of the three patients who died in the high ejection fraction group died as a result of intracerebral hemorrhage from thrombolytic therapy. Ejection fraction was lower in nonsurvivors (32.3+/-10.3 vs. 46.3+/-13%) than in survivors, p < 0.0002. Wall motion score index (WMSI) of < 1.4 was associated with a 2.9% 30-day mortality (two deaths in 76 patients); WMSI of > or = 1.4 was associated with a 17.6% 30-day mortality (22 deaths in 125 patients), p = 0.0007. Average WMSI was higher in the nonsurvivors (1.95+/-0.5) than in survivors (1.52+/-0.45), p = 0.00001. CONCLUSIONS: Echocardiographic assessment of left ventricular function during the first 24 h after an acute Q-wave MI can be performed in all patients regardless of stability. High-risk patients are identified early in the hospital course, with relative ease, at no risk and at an acceptable cost. An ejection fraction < 45% or WMSI > or = 1.4 identifies patients who are at a high risk of dying within 30 days. These are the patients who may benefit most from aggressive medical therapy and early angiography to assess coronary pathology.

Humans↗