PubMed Health⌕ Search

Biomedical subjects

K Cheney

Publications and source records attributed to K Cheney.

10 recordsLinked to original sources
PubMed2006

Vif-deficient HIV reverse transcription complexes (RTCs) are subject to structural changes and mutation of RTC-associated reverse transcription products.

Reverse transcription (RTn) in HIV-infected cells occurs in a nucleoprotein complex termed the reverse transcription complex (RTC). RTCs containing RT activity and integrase (IN) were shown to be heterogeneous in size and density on sucrose velocity and equilibrium gradients. WT and Vif-deficient (Deltavif) RTCs produced by infection with virus from permissive cells displayed similar sedimentation characteristics, while RTCs from Deltavif virus produced in non-permissive cells demonstrated a reduction in the major RTC form and more of the RTn products in rapidly sedimenting structures. APOBEC3G derived from virions did not co-sediment with RTCs, but RTCs from Deltavif infections showed elevated levels of mutations in RTn products, consistent with APOBEC3G and other mutational mechanisms. The most mutated transcripts were present within rapidly sedimenting RTCs. Thus, virus without functional vif, produced from non-permissive cells, forms abnormal RTCs that contain increased mutation of RTC-associated RTn products in newly infected target cells.

APOBEC-3G Deaminase↗
PubMed2001

Comparison of methods for assessment of minimal residual disease in childhood B-lineage acute lymphoblastic leukemia.

The level of minimal residual disease (MRD) early in treatment of acute lymphoblastic leukemia (ALL) strongly predicts the risk of marrow relapse. As a variety of methods of varying complexity have been separately used for detecting and quantifying MRD, we compared the prognostic utility of three methods measurement of blast percentage on day 14 of treatment, detection of monoclonality on day 14 or day 35, and measurement of MRD by PCR-based limiting dilution analysis on day 14 or day 35. The study group comprised 38 children aged 1-15 with Philadelphia-negative B-lineage ALL who were uniformly treated and followed until relapse or for a minimum of 5 years. We also studied some of the technical factors which influence the ability to detect MRD. Measurement of blast percentage on day 14 by an expert morphologist, detection of monoclonality on day 35, and PCR-based measurement of MRD levels on days 14 and 35 all showed significant ability to divide patients into prognostic groups. Measurement of blast percentage on day 14 by routine morphology or detection of monoclonality on day 14 were not useful. The quality of DNA samples varied greatly, as determined by amplifiability in the PCR. However, virtually all amplifiable leukemic targets in a sample were detectable which suggests that the level of detection achieved by limiting dilution analysis is essentially determined by the amount of DNA which it is practicable to study. We conclude that quantification of MRD at the end of induction provides the full range of prognostic information for marrow relapse but is complex; detection of monoclonality on day 35 is simple and has good positive predictive value; and quantification of MRD on day 14 merits further study. PCR-based methods for measurement of MRD levels should incorporate a correction for variation in DNA amplifiability.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Survival after a severe iron poisoning treated with intermittent infusions of deferoxamine.

Iron poisoning is the most common cause of overdose mortality in children under six years of age and there are no reports of survival with iron levels > 2687 mumol/L (> 15,000 micrograms/dL). A 22-month-old male was brought to the emergency department by his parents after ingesting an estimated 50 ferrous sulfate tablets (60 mg elemental iron/tablet) several hours earlier. Despite spontaneous emesis and gastric lavage his condition deteriorated and he was found to have a serum iron of 2992 mumol/L (16,706 micrograms/dL). During the first four days in the intensive care unit, he developed coma, metabolic acidosis, hypovolemic and cardiogenic shock, liver failure, coagulopathy and adult respiratory distress syndrome. He was treated with a unique deferoxamine dosage schedule (25 mg/kg/h for 12 h/d x 3 d), mechanical ventilation, Swan-Ganz catheter monitoring, dopamine/nitroprusside therapy, blood product, bicarbonate, electrolyte and volume replacement. After a prolonged hospital course complicated primarily by gastric outlet obstruction he was dismissed on full oral feedings, gaining weight, and neurologically intact. Swan-Ganz catheter monitoring guided the management of this patient's shock, iron-induced cardiac failure, and deferoxamine mesylate induced adult respiratory distress syndrome. Further experience and research is required to determine the most appropriate deferoxamine mesylate dosing schedule and our experience expands the range for possible survival after massive iron overdose.

Deferoxamine↗
PubMed1982

Childhood T-cell acute lymphoblastic leukaemia expressing "Ia-like" antigen:" a case report.

A 4-year-old girl presenting with vomiting, abdominal pain, and renal failure was found to have gross hepatosplenomegaly, a renal mass, and bilateral pleural effusions. A diagnosis of acute lymphoblastic leukaemia (ALL) was suggested by a peripheral white cell count (WCC) of 119,000 x 10(6)mm3, 57% blasts, 22% lymphocytes, and confirmed by bone marrow examination. Lymphocyte surface marker studies at diagnosis enabled classification as a T-ALL, with a significant proportion of the T cells also bearing receptors for the third component of complement (C3). Seventy-two percent of the peripheral blood mononuclear cells reacted with anti-Ia monoclonal antibody (FMC44), and a smaller proportion (25%) carried receptors for the Fc portion of IgG. The T-classification of this ALL was verified at central nervous system (CNS) relapse and at a subsequent nodal relapse. Double-marker studies on cells from the infiltrated lymph node prepared in suspension confirmed the presence of Ia-positive T cells. The Ia marker is usually a useful discriminant between T and non-T cells in normal and ALL cell populations. The case described here highlights the need for a panel of markers to be used in classification of childhood ALL and supports the suggestion that there is a distinct subtype of Ia-positive T-ALL.

Antigens, Surface↗
PubMed1978

Successful restoration of immunity in the DiGeorge syndrome with fetal thymic epithelial transplant.

A 13-month-old girl presented with right upper lobe pneumonia and hypocalcaemic seizures: investigations showed hypoparathyroidism and impaired cell-mediated immune responses. Other features of the DiGeorge syndrome included hypertelorism, short philtrum of the lip, right-sided aortic arch, and aberrant origin of the left subclavian artery. Successful restoration of the immunodeficiency was achieved by transplantation of fetal thymic epithelium.

DiGeorge Syndrome↗