Alternative method of oral administration by peanut butter pellet formulation results in target engagement of BACE1 and attenuation of gavage-induced stress responses in mice.

Development of novel therapeutic agents aimed at treating neurodegenerative disorders such as Alzheimer's and Parkinson's diseases require chronic and preferentially oral dosing in appropriate preclinical rodent models. Since many of these disease models involve transgenic mice that are frequently aged and fragile, the commonly used oro-gastric gavage method of drug administration often confounds measured outcomes due to repeated stress and high attrition rates caused by esophageal complications. We employed a novel drug formulation in a peanut butter (PB) pellet readily consumed by mice and compared the stress response as measured by plasma corticosterone levels relative to oral administration via traditional gavage. Acute gavage produced significant elevations in plasma corticosterone comparable to those observed in mice subjected to stress-induced hyperthermia. In contrast, corticosterone levels following consumption of PB pellets were similar to levels in naive mice and significantly lower than in mice subjected to traditional gavage. Following sub-chronic administration, corticosterone levels remained significantly higher in mice subjected to gavage, relative to mice administered PB pellets or naive controls. Furthermore, chronic 30day dosing of a BACE inhibitor administered via PB pellets to PSAPP mice resulted in expected plasma drug exposure and Aß40 lowering consistent with drug treatment demonstrating target engagement. Taken together, this alternative method of oral administration by drug formulated in PB pellets results in the expected pharmacokinetics and pharmacodynamics with attenuated stress levels, and is devoid of the detrimental effects of repetitive oral gavage.

Monitoring rainwater and seaweed reveals the presence of (131)I in southwest and central British Columbia, Canada following the Fukushima nuclear accident in Japan.

Detailed analysis of (131)I levels in rainwater and in three species of seaweed (Fucus distichus Linnaeus, Macrocystis pyrifera, and Pyropia fallax) collected in southwest British Columbia and Bella Bella, B.C., Canada was performed using gamma-ray spectroscopy following the Fukushima nuclear power plant accident on March 11, 2011. Maximum (131)I activity was found to be 5.8(7) Bq/L in rainwater collected at the campus of Simon Fraser University in Burnaby, B.C. nine days after the accident. Concomitantly, maximum observed activity in the brown seaweed F. distichus Linnaeus was observed to be 130(7) Bq/kg dry weight in samples collected in North Vancouver 11 days following the accident and 67(6) Bq/kg dry weight in samples collected from the Bamfield Marine Sciences Centre on Vancouver Island 17 days following the accident. The (131)I activity in seaweed samples collected in southwest B.C. following the Fukushima accident was an order of magnitude less than what was observed following Chernobyl. Iodine-131 activity in F. distichus Linnaeus remained detectable for 60 days following the accident and was detectable in each seaweed species collected. The Germanium Detector for Elemental Analysis and Radioactivity Studies (GEARS) was modeled using the Geant4 software package and developed as an analytical tool by the Nuclear Science group in the Simon Fraser University Department of Chemistry for the purpose of these measurements.

Multiplex ligation-dependent probe amplification versus multiprobe fluorescence in situ hybridization to detect genomic aberrations in chronic lymphocytic leukemia: a tertiary center experience.

Cytogenetic abnormalities play a major role in the prognosis of patients with chronic lymphocytic leukemia (CLL). Several methods have emerged to try to best identify these abnormalities. We used fluorescence in situ hybridization (FISH) to determine the frequency of cytogenetic changes in our CLL patient population. We also evaluated the effectiveness of multiplex ligation-dependent probe amplification (MLPA) in detecting these abnormalities. Sixty-two B-CLL patients and 20 healthy controls were enrolled, and FISH and MLPA analyses were performed on peripheral blood samples. Using FISH, genomic aberrations were found in 73% of patients and presented as follows: single 13q14.3 deletion (60%), trisomy 12 (7%), ATM deletion (6%), 17p13.1 deletion (2%). MLPA analyses done on 61/62 patients showed sensitivity and specificity values of 90% and 100% respectively. MLPA revealed several additional copy number changes, the most common being 19p13 (LDLR and CDKN2D). Moreover, the cost for MLPA analysis, including technical time and reagents, is 86% less than FISH. In conclusion, cytogenetic abnormalities are a common finding in CLL patients, and MLPA is a reliable approach that is more cost effective and faster than FISH. Despite MLPA limitations of sensitivity, it can be used as a first-line screen and complementary test to FISH analysis.

Abeta deposition and related pathology in an APP x PS1 transgenic mouse model of Alzheimer's disease.

A transgenic mouse bearing mutant transgenes linked to familial forms of Alzheimer's disease (AD) for the amyloid precursor protein and presenilin-1 (TASTPM) showed Abeta plaque deposition and age-related histological changes in associated brain pathology. The Abeta present was of multiple forms, including species with a C-terminus at position 40 or 42, as well as an N-terminus at position 1 or truncated in a pyro-3-glutamate form. Endogenous rodent Abeta was also present in the deposits. Laser capture microdissection extracts showed that multimeric forms of Abeta were present in both plaque and tissue surrounding plaques. Associated with the Abeta deposits was evidence of an inflammatory response characterised by the presence of astrocytes. Also present in close association with the deposits was phosphorylated tau and cathepsin D immunolabelling. The incidence of astrocytes and of phosphorylated tau and cathepsin D load showed that both of these potential disease markers increased in parallel to the age of the mice and with Abeta deposition. Immunohistochemical labelling of neurons in the cortex and hippocampus of TASTPM mice suggested that the areas of Abeta deposition were associated with the loss of neurons. TASTPM mice, therefore, exhibit a number of the pathological characteristics of disease progression in AD and may provide a means for assessment of novel therapeutic agents directed towards modifying or halting disease progression.

Dynamic soft tissue mobilisation increases hamstring flexibility in healthy male subjects.

OBJECTIVES: The purpose of this study was to investigate the effect of dynamic soft tissue mobilisation (STM) on hamstring flexibility in healthy male subjects. METHODS: Forty five males volunteered to participate in a randomised, controlled single blind design study. Volunteers were randomised to either control, classic STM, or dynamic STM intervention. The control group was positioned prone for 5 min. The classic STM group received standard STM techniques performed in a neutral prone position for 5 min. The dynamic STM group received all elements of classic STM followed by distal to proximal longitudinal strokes performed during passive, active, and eccentric loading of the hamstring. Only specific areas of tissue tightness were treated during the dynamic phase. Hamstring flexibility was quantified as hip flexion angle (HFA) which was the difference between the total range of straight leg raise and the range of pelvic rotation. Pre- and post-testing was conducted for the subjects in each group. A one-way ANCOVA followed by pairwise post-hoc comparisons was used to determine whether change in HFA differed between groups. The alpha level was set at 0.05. RESULTS: Increase in hamstring flexibility was significantly greater in the dynamic STM group than either the control or classic STM groups with mean (standard deviation) increase in degrees in the HFA measures of 4.7 (4.8), -0.04 (4.8), and 1.3 (3.8), respectively. CONCLUSIONS: Dynamic soft tissue mobilisation (STM) significantly increased hamstring flexibility in healthy male subjects.

Spectrum of HNF1A and GCK mutations in Canadian families with maturity-onset diabetes of the young (MODY).

PURPOSE: Maturity-onset diabetes of the young (MODY) is a subtype of type 2 diabetes characterized by autosomal-dominant inheritance and early onset. The pathophysiology of MODY is primarily defective insulin secretion resulting from mutations in at least 6 different genes. Most affected patients harbour mutations in either GCK (encoding glucokinase, also called MODY2) and HNF1A (encoding hepatic nuclear factor-1alpha, also called MODY3). We studied Canadian probands to determine if they had mutations in MODY2 or MODY3 genes. METHOD: We used genomic DNA sequencing of probands from 9 previously unreported Canadian MODY families. RESULTS: Five MODY probands had mutations in HNF1A, of which 4 were novel (namely IVS5-1delTAG, E275fsdelGAAG, F268S and L44fsdelC) and 4 had mutations in GCK, of which 2 were novel (E237K and L324P). These mutations expand the spectrum of MODY mutations and bring the total number of Canadian MODY families that have been molecularly defined in our laboratory to 15 (8 MODY3 and 7 MODY2). CONCLUSION: Because of the growing evidence that molecular diagnosis may affect prognosis and treatment, this information may be important in future for Canadian MODY families and their physicians.

Associations between genetic polymorphisms of Phase I and II metabolizing enzymes, p53 and susceptibility to esophageal adenocarcinoma.

The objectives of this exploratory case-control study were to evaluate whether genetic polymorphisms of selected Phase I and II metabolizing enzymes are associated with the risk of developing primary esophageal adenocarcinoma, and to investigate potential associations between genotypes and p53 tumor suppressor gene alterations. Cases comprised 45 patients with surgically resected esophageal adenocarcinomas, defined according to strict clinico-pathologic criteria. PCR-based assays (RFLP/SSCP) were used to genotype cytochrome P450 (CYP) 1A1 [MspI; Ile:Val], microsomal epoxide hydroxylase (mEH) (fast and slow alleles), and glutathione S-transferase (GST) T1, M1 and P1. Healthy controls (n=45) from the same geographic region were matched for age, gender and smoking history. For GSTP1, the Ile/Val (a/b) and Val/Val (b/b) variants were seen at increased frequency in cases compared to controls (49% versus 27% and 15% versus 9%, respectively), although these differences achieved only borderline statistical significance (P=0.09). For mEH (exon 3), the presence of the Tyr polymorphism (slow allele) was reduced in cases (42%) compared to controls (53%; P=0.05). Predicted high mEH activity was seen more frequently in cases than controls (OR, 2.2; 95% CI, 0.7-7.3). Polymorphism frequencies for GSTT1, GSTM1, and CYP1A1 were not statistically different between cases and controls. Cases with the GSTT1 null genotype had tumors with altered p53 more frequently than did cases with the common form of GSTT1 (25 versus 6%, respectively; P=0.08). We conclude that polymorphisms of GSTP1 and mEH may be implicated in individual susceptibility to esophageal adenocarcinoma, possibly as a result of increased Phase I activation (mEH) and impaired Phase II detoxification (GSTP1). GSTT1 may also play a role in esophageal tumorigenesis through a pathway that involves abnormalities in the p53 tumor suppressor gene.

ING1 and p53 tumor suppressor gene alterations in adenocarcinomas of the esophagogastric junction.

The aim of this study was to characterize molecular alterations of the recently reported candidate tumor suppressor gene, ING1, and to explore the relationship between ING1 and p53 in a well-defined series of adenocarcinomas of the esophagogastric junction (AdEGJ). Polymerase chain reaction (PCR)-based assays were used to characterize ING1 and p53 alterations, relative to histologically normal esophageal mucosa. Two tumors were found to have ING1 mutations: one novel missense mutation (AGC(Ser)-->ATC(Ile)) at codon 147, and one silent mutation (TCG(Ser)-->TCA(Ser)) at codon 173. Reduced expression of the two major alternatively spliced ING1 messenger RNA variants, p47(ING1a) and p33(ING1b) was variable, but was reduced (1.2-10-fold) in 12 of 19 AdEGJs compared to normal esophageal epithelium. No association between p53 and ING1 alterations was apparent. We conclude that reduced ING1 expression is frequently associated with AdEGJ tumorigenesis, further supporting its role as a tumor suppressor gene, and that ING1 expression is independent of p53 status.

Association between Breus' mole and partial hydatidiform mole: chance or can hydropic villi precipitate placental massive subchorionic thrombosis?

Breus' mole (massive subchorionic hematoma) is a rare entity most often found in the placentae of macerated stillborn fetuses. Previously considered to represent a postmortem event, recent evidence suggests that it occurs prior to fetal demise. A 23-week gestation male neonate was delivered of a 23-year-old gravida 3, para 2 woman and survived for 49 min. An autopsy with chromosomal studies resulted in a diagnosis of triploidy. Placental examination showed the presence of both Breus' mole and also partial hydatidiform mole. DNA samples extracted from portions of the fresh hematoma and from the fetal spleen were compared using molecular techniques. PCR analysis showed the presence of Y chromosome specific DNA in the placental clot, but a semiquantitative Southern blot demonstrated that roughly 85% of the clot DNA was of maternal origin. These findings suggest that Breus' mole represents primarily maternal thrombosis rather than fetal hemorrhage. We hypothesize that the partial mole could have contributed to the formation of the Breus' mole as some of the hydropic villi may have focally obstructed the maternal venous return from the intervillus space causing sluggish flow and promoting thrombosis. A review of the literature on Breus' mole shows that the majority of reported cases have not included cytogenetic findings. However, several authors have reported an association with triploidy and other chromosomal anomalies characterized by scattered placental hydropic villi. Thus, we suggest that obstruction of maternal venous return by hydropic villi may have played a contributory role in some of these other reported cases.

Cell-derived apolipoprotein E (ApoE) particles inhibit vascular cell adhesion molecule-1 (VCAM-1) expression in human endothelial cells.

Sub-endothelial infiltration of monocytes occurs early in atherogenesis and is facilitated by cell adhesion molecules that are up-regulated on activated endothelium. Apolipoprotein E (apoE) helps protect against atherosclerosis, in part, because apoE particles secreted by macrophages have local beneficial effects at lesion sites. Here, we hypothesize that such protection includes anti-inflammatory actions and investigate whether cell-derived apoE can inhibit tumor necrosis factor-alpha-mediated up-regulation of vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVECs). Two models were used to mimic endothelial exposure to macrophage-derived apoE. In the first, HUVECs were transiently transfected to secrete apoE; VCAM-1 induction inversely correlated with secretion of apoE into the media (r = -0.76, p < 0.001). In the second, incubation of HUVECs with media from recombinant Chinese hamster ovary (CHO) cells expressing apoE (CHO(apoE)) also reduced VCAM-1 in a dose-dependent manner (r = -0.70, p < 0.001). Characterization of CHO(apoE) cell-derived apoE revealed several similarities to apoE particles secreted by human blood monocyte-derived macrophages. The suppression of endothelial activation by apoE most likely occurs via stimulation of endothelial nitric oxide synthase; apoE increased levels of intracellular nitric oxide and its surrogate marker, cyclic guanosine monophosphate, while the nitric oxide synthase inhibitor, ethyl-isothiourea, blocked its effect. We propose that apoE secreted locally at lesion sites by macrophages may be anti-inflammatory by stimulating endothelium to release NO and suppress VCAM-1 expression.

Compartmentalization of beta-secretase (Asp2) into low-buoyant density, noncaveolar lipid rafts.

Recent epidemiological studies show a reduced prevalence of Alzheimer's disease (AD) in patients treated with inhibitors of cholesterol biosynthesis. Moreover, the cholesterol-transport protein, apolipoprotein E4, and elevated cholesterol are important risk factors for AD. Additionally, in vitro and in vivo studies show that intracellular cholesterol levels can modulate the processing of amyloid precursor protein (APP) to beta-amyloid, the major constituent of senile plaques. Cholesterol plays a crucial role in maintaining lipid rafts in a functional state. Lipid rafts are cholesterol-enriched membrane microdomains implicated in signal transduction, protein trafficking, and proteolytic processing. Since APP, beta-amyloid, and the putative gamma-secretase, presenilin-1 (PS-1), have all been found in lipid rafts, we hypothesized that the recently identified beta-secretase, Asp2 (BACE1), might also be present in rafts. Here, we report that recombinant Asp2 expressed in three distinct cell lines is raft associated. Using both detergent and nondetergent methods, Asp2 protein and activity were found in a light membrane raft fraction that also contained other components of the amyloidogenic pathway. Immunoisolation of caveolin-containing vesicles indicated that Asp2 was present in a unique raft population distinct from caveolae. Finally, depletion of raft cholesterol abrogated association of Asp2 with the light membrane fraction. These observations are consistent with the raft localization of APP processing and suggest that the partitioning of Asp2 into lipid rafts may underlie the cholesterol sensitivity of beta-amyloid production.

Localization of apolipoprotein E receptor 2 to caveolae in the plasma membrane.

The LDL receptor (LDL-R) promotes the specific endocytosis and lysosomal delivery of extracellular lipoprotein ligands via clathrin-coated pits. It was widely assumed that other closely related members of the LDL-R gene family would have similar functions, but recent experimental evidence has revealed that one such protein, apolipoprotein E receptor 2 (apoER2), has a critical role as an "outside-in" signal transducer in the brain. ApoER2 signaling appears to require interaction between its cytoplasmic domain and adapter molecules such as Dab1, JIP 1 and JIP 2, and PSD-95. Many of the receptors for other signaling pathways affected by such adapter molecules are compartmentalized into specialized microdomains within the plasma membrane termed caveolae. Here, we show that apoER2, but not LDL-R, is localized to caveolae, supporting the concept that its physiological role is in cell signaling, rather than in endocytosing ligands.

Gene correction of the apolipoprotein (Apo) E2 phenotype to wild-type ApoE3 by in situ chimeraplasty.

Apolipoprotein (apo) E is a polymorphic plasma protein, synthesized mainly by liver. Here, we evaluate whether synthetic DNA-RNA oligonucleotides (chimeraplasts) can convert a dysfunctional isoform, apoE2 (C --> T, R158C), which causes Type III hyperlipidemia and premature atherosclerosis, into apoE3. First, we treated recombinant Chinese hamster ovary cells stably secreting apoE2 with a 68-mer apoE2 to apoE3 chimeraplast. About one-third of apoE2 was converted to apoE3, and the repair was stable through 12 passages. Subcloning treated cells produced both apoE2 and apoE3 clones. Direct sequencing and reverse transcription polymerase chain reaction confirmed the genotype, whereas phenotypic change was verified by isoelectric focusing and immunoblotting of secreted proteins. Second, we established that the APOE2 gene can be targeted both in vivo, using transgenic mice overexpressing human apoE2, and in chromosomal context, using cultured lymphocytes from a patient homozygous for the epsilon2 allele. We conclude that chimeraplasty has the potential to convert the apoE2 mutation in patients with Type III hyperlipidemia to apoE3.

Serial measurements of hematologic counts during the active phase of human granulocytic ehrlichiosis.

To describe the changes that occur in blood count parameters during the natural course of human granulocytic ehrlichiosis, we designed a retrospective cross-sectional case study of 144 patients with human granulocytic ehrlichiosis and matched controls who had a different acute febrile illness. Patients from New York State and the upper Midwest were evaluated from June 1990 through December 1998. Routine complete blood counts and manual differential leukocyte counts of peripheral blood were performed on blood samples that were collected during the active illness, and values were recorded until the day of treatment with an active antibiotic drug. Thrombocytopenia was observed more frequently than was leukopenia, and the risk of having ehrlichiosis varied inversely with the granulocyte count and the platelet count. Patients with ehrlichiosis displayed relative and absolute lymphopenia and had a significant increase in band neutrophil counts during the first week of illness. Knowledge of characteristic complete blood count patterns that occur during active ehrlichiosis may help clinicians to identify patients who should be evaluated specifically for ehrlichiosis and who should receive empiric antibiotic treatment with doxycycline.

Intramuscular injection of a plasmid vector expressing human apolipoprotein E limits progression of xanthoma and aortic atheroma in apoE-deficient mice.

Apolipoprotein-E (apoE) protects against coronary artery disease via hepatic removal of atherogenic remnant lipoproteins, sequestration of cholesterol from vessel walls and local anti-oxidant, anti-platelet and anti-inflammatory actions. ApoE gene transfer may thus ameliorate a hyperlipidaemic profile and have beneficial effects at lesion sites to prevent or regress atherosclerosis, a concept endorsed by adenoviral-mediated hepatic expression studies. Here, using plasmid vectors expressing allelic human apoE2 or apoE3 isoforms, skeletal muscle was evaluated as an effective secretory platform for apoE gene augmentation. Transfected myoblasts and myotubes were found to efficiently secrete recombinant apoE in vitro as spherical 10-16 nm lipoprotein particles with pre-beta mobility. Intramuscular plasmid injection in apoE(-/-) mice, which develop spontaneous atherosclerotic plaque and xanthoma resulted in expression and secretion of apoE. Human apoE mRNA was detected by RT-PCR in injected muscles and, although concentrations of apoE3, which is rapidly cleared from plasma, were near ELISA detection limits, levels of plasma apoE2 were measurable (17.5 +/- 4.3 ng/ml). To assess whether muscle-based expression of apoE2 could inhibit atherogenesis, long-term follow-up studies were conducted. Although hyperlipidaemia was not reduced in treated animals, end-point pathology showed clear retardation of atherosclerotic and xanthomatous lesions. Up to 9 months following a single apoE2 plasmid administration, atherosclerotic lesion coverage in proximal aorta was significantly reduced by 20-30% (P < 0.01), whereas development of gross dorsal xanthoma (>5 mm diameter) was effectively reduced to zero. We conclude that expression of apoE from ectopic muscle sites has therapeutic potential to limit progression of atherosclerosis.

Identification and characterization of LRP8 (apoER2) in human blood platelets.

Recently, we reported that apoE inhibits platelet reactivity by stimulating NO release and postulated apoE-receptor activation of intracellular NO synthase (eNOS). Here, we implicate a low density lipoprotein receptor (LDL-R) family member by studying ligand requirements using purified apoE isoforms, synthetic peptides, and the receptor antagonist, receptor-associated protein (RAP). Then, using a homology cloning approach and degenerate PCR primers to amplify the conserved Cys-rich binding domain of the LDL-R family, this receptor was identified as LRP8 (formerly termed, apoER2), a newly described brain protein with several splice variants. Immunoprecipitation of platelet membranes with anti-peptide antisera confirmed protein expression, while analysis of RNA from platelets and two megakaryocytic cell lines (Meg-01 and HEL) disclosed that the major LRP8 transcript lacked binding repeats 4-6 (LRP8delta4-6) but contained the full-length cytoplasmic tail. Sequence analysis of cytoplasmic LRP8 revealed several peptide motifs with potential for cellular signaling and we propose this as a rational mechanism through which apoE inhibits platelet aggregation.

Mutations in NPC1 highlight a conserved NPC1-specific cysteine-rich domain.

Niemann-Pick type II disease is an autosomal recessive disorder characterized by a defect in intracellular trafficking of sterols. We have determined the intron/exon boundaries of eight exons from the conserved 3' portion of NPC1, the gene associated with most cases of the disease. SSCP analyses were designed for these exons and were used to identify the majority of mutations in 13 apparently unrelated families. Thirteen mutations were found, accounting for 19 of the 26 alleles. These mutations included eight different missense mutations (including one reported by Greer et al. [1998]), one 4-bp and two 2-bp deletions that generate premature stop codons, and two intronic mutations that are predicted to alter splicing. Two of the missense mutations were present in predicted transmembrane (TM) domains. Clustering of these and other reported NPC1 mutations in the carboxy-terminal third of the protein indicates that screening of these exons, by means of the SSCP analyses reported here, will detect most mutations. The carboxy-terminal half of the Npc1 protein shares amino acid similarity with the TM domains of the morphogen receptor Patched, with the largest stretch of unrelated sequence lying between two putative TM spans. Alignment of this portion of the human Npc1 protein sequence with Npc1-related sequences from mouse, yeast, nematode, and a plant, Arabidopsis, revealed conserved cysteine residues that may coordinate the structure of this domain. That 7 of a total of 13 NPC1 missense mutations are concentrated in this single Npc1-specific domain suggests that integrity of this region is particularly critical for normal functioning of the protein.

Apoptotic fraction in childhood ALL assessed by DNA in situ labelling is ploidy independent.

BACKGROUND: Apoptotic cell fraction and presence or degree of aneuploidy may both affect treatment outcome in childhood acute lymphoblastic leukaemia (ALL), which is largely defined by drug resistance. Independence of the variables is at present not established. Until the development of in situ labelling of cells committed to the apoptotic pathway, the fraction of cells in apoptosis could not be determined objectively. AIM: To determine the relationship between apoptotic cell fraction and karyotype in childhood ALL using in situ labelling. METHODS: 1.3.1. Study Groups and Samples. Diagnostic, pretreatment bone marrow trephine and aspirate samples of 24 consecutive, unselected cases of childhood ALL were included in the study: Normal karyotype (n = 11, 5M,6F), high hyperdiploid aneuploidy (DNA index > 1.5, n = 7, 1M,6F), complex karyotypic anomalies (n = 6, 5M,1F). 1.3.2. Apoptotic Cell Labelling. In situ labelling of the 3'-OH ends of the apoptosis specific DNA (Klenow) fragment (Frag-EL, CalBiochem, USA). 1.3.3. Quantitation. Apoptotic cell fraction was established using 10 systematically random fields of > 20 nuclei. Results were tabled per group. After calculations of means, differences between groups were assessed using t-test. RESULTS: Apoptotic cell fraction, ranging from < 1 to 95%, did not differ statistically significant between the three study groups. CONCLUSION: Apoptotic cell fraction in childhood leukaemia is independent of ploidy status and euploid karyotypic anomalies.

PCNA bearing structures are retained in apoptotic phase of childhood ALL cell cycle.

BACKGROUND: Drug resistance to DNA directed therapy may depend on proliferative as well as apoptotic cell fraction. PCNA/Ki67 ratio excess, possibly reflecting DNA excision repair, is of additional interest to drug resistance in MTT testing. The cell cycle phase/antigen expression pattern in childhood acute lymphoblastic leukemia (ALL) is not known. AIMS: To study the relationship between nuclear expression of PCNA, Ki-67 and Frag-EL positivity in childhood ALL. METHODS: 1.3.1. Study Groups. Diagnostic bone marrow trephine biopsies of 32 consecutive unselected cases of childhood ALL were included in the study. 1.3.2. Immunohistochemistry. Commercially available Moab PCNA (PC10, DAKO, USA), Ki-67 (MM1, NovaCastra, UK) were used to label cycling cells in routinely processed 5 microns paraffin sections. 1.3.3. In-Situ Labelling of Apoptotic Cells. The 3'-OH ends of apoptosis specific DNA fragments were labelled in-situ on subsequent 10 microns sections (Frag-EL, CalBiochem, USA). 1.3.4. Quantitation. After blinding and randomisation, 10 systematic random fields of > 20 nuclei and nuclear size bias correction was used to determine positive nuclei fraction. RESULTS: While the sum of apoptotic and proliferative cell fraction (Ki-67 + Frag-EL%) equalled 100% in 5/32 cases, PCNA expression into at least the early phases of apoptosis ([%PCNA-%K-67] > [100-%Frag-EL] was found in 17/32 cases. CONCLUSIONS: PCNA/Ki67 ratio excess may not reflect DNA excision repair activity but rather slow degradation of antigen bearing structures limiting relevance to drug resistance study.