A novel, palatable paediatric oral formulation of midazolam: pharmacokinetics, tolerability, efficacy and safety.

Midazolam is one of many bitter drugs where provision of a suitable oral paediatric formulation, particularly in the pre-anaesthetic setting, remains a challenge. To overcome this problem, a novel chocolate-based tablet formulation has been developed with positive pre-clinical results. To further investigate the potential of this formulation, 150 children aged 3-16 years who were prescribed midazolam as a premedication were randomly assigned to receive 0.5 mg.kg-1 either as the novel formulation or an intravenous solution given orally, which is the current standard at our institution. Tolerability was assessed by each child, parent and nurse using a 5-point facial hedonic scale and efficacy was determined as the time to onset of sedation. Blood samples for midazolam and 1-hydroxymidazolam levels were analysed using high-performance liquid chromatography. Population pharmacokinetics were evaluated using non-linear mixed effects modelling. The novel formulation had significantly improved tolerability scores from children, parents and nurses (all p < 0.001). Time to effect was not different between the groups (p = 0.140). The pharmacokinetics of midazolam and 1-hydroxymidazolam were able to be modelled simultaneously. The novel formulation was subject to a higher estimated first-pass metabolism compared with the intravenous solution (8.6% vs. 5.0%) and a significantly lower relative bioavailability of 82.1% (p = 0.013), with no other significant differences. Exposure relative to dose was in the range previously reported for midazolam syrup. We conclude that the novel chocolate-based formulation of midazolam provides improved tolerability while remaining efficacious with suitable pharmacokinetics when used as a premedicant for children.

Systematic chemical and molecular profiling of MLL-rearranged infant acute lymphoblastic leukemia reveals efficacy of romidepsin.

To address the poor prognosis of mixed lineage leukemia (MLL)-rearranged infant acute lymphoblastic leukemia (iALL), we generated a panel of cell lines from primary patient samples and investigated cytotoxic responses to contemporary and novel Food and Drug Administration-approved chemotherapeutics. To characterize representation of primary disease within cell lines, molecular features were compared using RNA-sequencing and cytogenetics. High-throughput screening revealed variable efficacy of currently used drugs, however identified consistent efficacy of three novel drug classes: proteasome inhibitors, histone deacetylase inhibitors and cyclin-dependent kinase inhibitors. Gene expression of drug targets was highly reproducible comparing iALL cell lines to matched primary specimens. Histone deacetylase inhibitors, including romidepsin (ROM), enhanced the activity of a key component of iALL therapy, cytarabine (ARAC) in vitro and combined administration of ROM and ARAC to xenografted mice further reduced leukemia burden. Molecular studies showed that ROM reduces expression of cytidine deaminase, an enzyme involved in ARAC deactivation, and enhances the DNA damage-response to ARAC. In conclusion, we present a valuable resource for drug discovery, including the first systematic analysis of transcriptome reproducibility in vitro, and have identified ROM as a promising therapeutic for MLL-rearranged iALL.

High expression of connective tissue growth factor accelerates dissemination of leukaemia.

To improve treatment of acute lymphoblastic leukaemia (ALL), a better understanding of disease development is needed to tailor new therapies. Connective tissue growth factor (CTGF/CCN2) is highly expressed in leukaemia cells from the majority of paediatric patients with B-lineage ALL (pre-B ALL). CTGF is a matricellular protein and plays a role in aggressive cancers. Here we have genetically engineered leukaemia cells to modulate CTGF expression levels. Elevated CTGF levels accelerated disease dissemination and reduced survival in NOD/SCID mice. In vitro studies showed that CTGF protein induces stromal cell proliferation, promotes adhesion of leukaemia cells to stromal cells and leads to overexpression of genes associated with cell cycle and synthesis of extracellular matrix (ECM). Corresponding data from our leukaemia xenograft models demonstrated that CTGF leads to increased proliferation of non-leukaemia cells and deposition of ECM in the bone marrow. We document for the first time a functional role of CTGF in altering disease progression in a lymphoid malignancy. The findings provide support for targeting the bone marrow microenvironment in aggressive forms of leukaemia.

The role of CCN family genes in haematological malignancies.

Haematological malignancies, although a broad range of specific disease types, continue to show considerable overlap in classification, and patients are treated using similar chemotherapy regimes. In this review we look at the role of the CCN family of matricellular proteins and indicate their role in nine haematological malignancies including both myeloid and lymphoid neoplasms. The potential for further haematological neoplasms with CCN family associations is argued by summarising the demonstrated role of CCN family genes in the differentiation of haematopoietic stem cells (HSC) and mesenchymal stem cells. The expanding field of knowledge encompassing CCN family genes and cancers of the HSC-lineage highlights the importance of extracellular matrix-interactions in both normal physiology and tumorigenesis of the blood, bone marrow and lymph nodes.

Strain analysis of hepatitis B virus on the basis of restriction endonuclease analysis of polymerase chain reaction products.

To assess the value of classifying hepatitis B virus (HBV) strains at the genomic level with products from the polymerase chain reaction (PCR), an HBV PCR DNA typing procedure was developed. The design of this method was based on the selective sensitivity of the PCR product to digestion with different restriction endonucleases and on the size of the fragment resulting from a specific nuclease digestion. On the basis of published nucleotide sequences of different HBV subtypes, a set of primers was selected within the preS-S region. One of the primers was 1679F containing 25 nucleotides (5'-GGGTGGAGCCCTCAGGCTCAGGGCA-3'), and the other was 2254R containing 24 nucleotides (5'-GAAGATGAGGCATAGCAGCAGGAT-3'). All of the reactive sera produced the same sized 575-bp identification band. The product was subjected to digestion by a selected panel of restriction endonucleases. By using prototype HBV of known subtype as a model, these restriction nuclease maps of the PCR product were subtype specific. Most adr subtype clinical samples produced predicted PCR DNA restriction nuclease fragmentation in accordance with the nucleotide sequence of the prototype virus. Occasionally, samples of either the adw or the ayw subtype gave discrepant results in which they appeared to be a different subtype or were resistant to the restriction nuclease digestion. This genetic alteration was consistent in the paired specimens from sexual transmission cases. These results show that the described procedures are applicable to HBV strain assessment.

Is terminal deoxynucleotidyl transferase an intracellular mutagen?

We have established stably transformed mammalian cell lines expressing recombinant human terminal deoxynucleotidyl transferase. A 58 kDa, enzymatically active protein is produced by these cell lines. Using the lacI gene of pJYMib shuttle vector as mutagenic target, we found no increase in mutation rates in cells expressing terminal deoxynucleotidyl transferase compared to controls. Our results suggest that the presence of terminal deoxynucleotidyl transferase alone in mammalian cells does not increase mutation rates.

Chromosome sublocalization of a cDNA for human DNA polymerase-beta to 8p11----p12.

We have localized a cDNA fragment that codes for human DNA polymerase-beta. Using somatic cell and in situ hybridization techniques, this cDNA was cloned by screening a human KM-3 cell cDNA library in lambda gt 11 for expression of fused beta-galactosidase-human DNA polymerase-beta proteins. We have mapped this human polymerase-beta gene to the short arm of chromosome 8 in the subregion 8p11----p12.

Expression of human terminal deoxynucleotidyl transferase in Escherichia coli.

A cloned DNA fragment related to pT17 containing a partial cDNA sequence of human terminal deoxynucleotidyl transferase was used as a probe to screen for the full length cDNA sequence of the enzyme in a lambda gt11 library constructed from human lymphoblastoid KM-3 cDNA. A recombinant containing a 2068-base pair insert was isolated and recloned into the EcoRI site of the sequencing plasmic pUC-8 as two subclones, pT711 and pT106. DNA sequencing and hybridization studies showed that pT711 contains the pT17 sequence and an additional 172 upstream nucleotides. pT711 represents the coding sequence for the carboxyl half of the terminal transferase protein. pT106, containing a 965-base pair insert, hybridizes to the same mRNA as pT711 on Northern blots and contains an open reading frame that is in phase with the reading frame of the insert in pT711. Amino acid sequencing of the 58-kDa peptide of the calf thymus terminal transferase failed, indicating that the N terminus is blocked. N-Terminal sequencing of a 56-kDa form of the protein produced 24 amino acids corresponding to the translated human cDNA coding sequence starting at residue 398 of the insert in pT106 with 83% homology between bovine and human sequence. The initiation codon is assigned to an ATG sequence at nucleotide 329 of the insert in pT106. Comparison of the translated human terminal transferase sequence with peptides from the calf thymus enzyme showed that the homology between the human and bovine enzyme is better than 90% among 263 amino acids determined. The coding sequences in pT106 and pT711 were recloned into an expression plasmid pUC-19 downstream from the lac promoter and in phase with the coding sequence of the lac Z gene. Lysates of bacteria carrying the reconstructed coding sequence of human terminal transferase contain a fused protein of 60 kDa that reacts with rabbit antibody to terminal transferase on immunoblots and exhibits enzyme activity. Isolation of this fused protein from bacterial lysates with mouse monoclonal antibody to human terminal transferase produces the expected protein of 60 kDa.

Molecular cloning of human terminal deoxynucleotidyltransferase.

A cDNA of the human terminal deoxynucleotidyltransferase (TdT; "terminal transferase," EC 2.7.7.31) was isolated from a human lymphoblastoid cell cDNA library in lambda gt 11 by using immunological procedures. Four inserts containing 723 to 939 base pairs were recloned in pBR322 for hybridization and preliminary sequence studies. mRNA selected by hybridization to recombinant DNA was translated to a 58-kDa peptide that specifically immunoprecipitated with rabbit antibodies to calf terminal transferase and mouse monoclonal antibody to human terminal transferase. Blot hybridization of total poly(A)+ RNA from KM3 (TdT+) cells with nick-translated pBR322 recombinant DNA detected a message of about 2000 nucleotides, sufficient to code for the 580 amino acids in the protein. mRNA from terminal transferase- cells gave no signal in hybrid selection or RNA blot hybridization. The complete sequence of the 939-base-pair insert sequence was obtained from deletions cloned in pUC8. The DNA sequence contains an open reading frame coding for 238 amino acids, about 40% of the protein. Three peptides isolated by HPLC from tryptic digests of succinylated 58-kDa calf thymus terminal transferase were sequenced, providing 20, 18, and 22 residues of peptide sequence. A search of the translated sequence of the 939-base-pair insert shows three regions beginning after arginine that have greater than 90% homology with the sequence determined from the calf thymus terminal transferase peptides. These results provide unambiguous evidence that the human terminal transferase sequence has been cloned.

The preparation of stroma-free hemoglobin by selective DEAE-cellulose absorption.

The preparation of stroma-free hemoglobin by selective DEAE-cellulose absorption is reported. The stroma-free hemoglobin prepared by this method is compared to the product obtained by crystallization from sodium phosphate. Both show normal serum potassium, sodium, and pH values, and no coagulant activity or blood type activity by blood type test. PAA gradient gel electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and isoelectric focusing in polyacrylamide gel all show the same well-defined bands in both preparations. The DEAE procedure requires 11 h as compared to 4 days for the crystallization method. The recovery of hemoglobin is 77% (less than 1% methemoglobin) in the DEAE preparation compared to 34% (greater than 3% methemoglobin) by the crystallization method. In addition, far fewer expensive materials are required.