PCR-free blood group genotyping using a nanobiosensor

BACKGROUND AND OBJECTIVES

The last two decades have seen major developments in genotyping assays to facilitate the procurement of red blood cell units to alloimmunized patients. To make genotyping faster, simpler and less costly, a nanotechnology approach based on metal/silica fluorescent nanoparticles and a polymer-based hybridization optical transducer was designed. The objectives of this study were (1) to verify whether this nanobiosensor has the ability to discriminate single nucleotide polymorphisms in non-amplified genomic DNA and (2) to establish whether the signal generated by the nanobiosensor is sufficiently intense to be detected by standard flow cytometry.

MATERIALS AND METHODS

Silver-core silica-shell fluorescent nanoparticles (Ag@SiO₂) were prepared, and amine-modified DNA probes were grafted to their surface. A cationic conjugated polymer was electrostatically bound to the surface probes to become optically active upon hybridization with a target. Two nanobiosensor formulations specific to DO*01 and DO*02 alleles were prepared. DNA was extracted from whole blood and mixed with the nanobiosensor for hybridization. The nanobiosensor fluorescence was measured by flow cytometry.

RESULTS

Nine volunteers were typed for Dombrock blood group antigens DO*01 and DO*02. A statistically significant increase in the optical transduction signal was observed for sequence-specific samples. All nine genotypes were correctly identified when compared to standardized PCR assays.

CONCLUSION

The nanobiosensor provides rapid and simple genotyping of blood group antigens from unamplified genomic DNA and can be measured using standard flow cytometers. This PCR-free approach could be applied to any known genetic polymorphism.

Red blood cell antigen portrait of self-identified black donors in Quebec

OBJECTIVES

The goal of this study was to establish a red blood cell antigen portrait of self-identified Black donors for the province of Quebec, Canada.

BACKGROUND

The demand for extensively phenotyped red blood cells is on the rise. A good example is the sickle cell patient cohort. To better answer their transfusion needs, Héma-Québec put forward great efforts to increase the recruitment of donors among cultural communities.

MATERIALS AND METHODS

In October 2009, an optional question was added on the record of donation to indicate the donor's ethnicity. Self-identified Black donors were extensively phenotyped by the Immunohematology Laboratory, whereas the Research and Development team genotyped red blood cell antigens to complete the picture.

RESULTS

Approximately 1500 self-identified Black donors have donated blood at least once since the beginning of the programme. Genotyping results predicted rare phenotypes: 18 S-s- (3 U-, 15 U+(w) ), 15 Js(a+b-), 5 Hy-, 3 Jo(a-), 34 hr(B) +(w) /- and 15 hr(B)-.

CONCLUSION

These Black donors, with or without a rare phenotype, are precious to the patient cohort depending on blood transfusions and to our organisation as the blood provider for the whole province of Quebec.

Consortium for Blood Group Genes (CBGG): 2009 report

Consortium for Blood Group Genes is a worldwide organization whose goal is to have a vehicle to interact, establish guidelines, operate a proficiency program, and provide education for laboratories involved in DNA and RNA testing for the prediction of blood group, platelet, and neutrophil antigens. Currently, the consortium operates with representatives from Brazil, Canada, and the United States. Membership is voluntary with the expectation that members actively contribute to discussions involving blood group genetics. This year witnessed a change in the standing committee membership and the institution of a representative for the human platelet antigens group. Looking forward, the consortium sees challenges for the nomenclature of blood group alleles and user-required specifications for laboratory information systems to store genotype information.

Set-up and routine use of a database of 10,555 genotyped blood donors to facilitate the screening of compatible blood components for alloimmunized patients

BACKGROUND AND OBJECTIVES

Large-scale genotyping of blood donors for red blood cell and platelet antigens has been predicted to replace phenotyping assays in the screening of compatible blood components for alloimmunized patients. Although several genotyping platforms have been described, novel procedures and processes are needed to perform genotyping efficiently and to maximize its benefits for blood banks.

MATERIALS AND METHODS

Here we describe the processes and procedures developed to introduce large-scale genotyping in our routine operations.

RESULTS

Preliminary cost-benefit analysis indicated that genotyping must target frequent blood donors (> 3 donations/year) to be efficiently used. A custom-designed computer application was developed to manage the whole project. It selects frequent donors among recent donations, prints coded labels to identify blood samples sent to the external genotyping laboratory, and stores genotyping results. It can search for donors compatible for any combination of the 22 genotyped antigens as well as consult the current inventory for the presence of the corresponding blood components. The phenotype of recovered components is confirmed by standard serology techniques prior to shipment to hospitals.

CONCLUSION

Since October 2007, 10 555 blood donors have been genotyped. The database is used on a regular basis to find compatible blood components with a genotype-phenotype concordance of 99.6%.

Interleukin 12 secretion enhances antitumor efficacy of oncolytic herpes simplex viral therapy for colorectal cancer

OBJECTIVE

To assess the strategy of combining oncolytic herpes simplex virus (HSV) therapy with immunomodulatory therapy as treatment for experimental colon cancer. The oncolytic HSV recombinant NV1023 and the interleukin 12 (IL-12)-secreting oncolytic NV1042 virus were evaluated in vitro and in vivo with respect to antitumor efficacy.

SUMMARY BACKGROUND DATA

Genetically engineered, replication-conditional, attenuated HSVs have shown oncolytic activity against a wide variety of solid malignancies. Other strategies for treating cancer have involved immunomodulation and cytokine gene transfer using viral vectors. This study has combined both of these strategies by inserting the murine IL-12 gene into a replication-competent HSV. This approach allows oncolytic therapy to replicate selectively within and lyse tumor cells while providing the host immune system with the cytokine stimulus necessary to recruit and activate inflammatory cells needed to enhance the antitumor effect.

METHODS

NV1023 is a multimutant HSV based on the wild-type HSV-1 F strain. NV1042 was created by insertion of the mIL-12 gene into NV1023. Cytotoxicity and viral proliferation of both NV1023 and NV1042 within murine CT26 colorectal cancer cells were first shown. Cells infected with NV1042 were then shown to produce significant levels of IL-12. Using an experimental flank model of colon cancer, mice were treated with both high and low doses of NV1023 or NV1042 and were followed up for both cure and reduction in tumor burden.

RESULTS

Both viruses could replicate within and kill CT26 cells in vitro, with 100% cytotoxicity achieved after infection by either virus. Only NV1042 could produce mIL-12. Therapy using high viral doses to treat animals in vivo showed equal efficacy between NV1023 and NV1042, with five of seven cures for each virus. When viral doses were lowered, only the cytokine-producing NV1042 virus could reduce tumor burden and cure animals of their disease.

CONCLUSIONS

Both NV1023 and NV1042 have the oncolytic potential to kill colon cancer cells at higher doses. Cytokine production by NV1042 may allow lower doses of viral therapy to be used without losing antitumor efficacy. The combination of oncolytic viral therapy and immunomodulatory strategies should be further investigated as treatment for colon cancer.

Cytokine gene transfer enhances herpes oncolytic therapy in murine squamous cell carcinoma

Replication-competent, attenuated herpes simplex viruses (HSV) have been demonstrated to be effective oncolytic agents in a variety of malignant tumors. Cytokine gene transfer has also been used as immunomodulatory therapy for cancer. To test the utility of combining these two approaches, two oncolytic HSV vectors (NV1034 and NV1042) were designed to express the murine GM-CSF and murine IL-12 genes, respectively. These cytokine-carrying variants were compared with the analogous non-cytokine-carrying control virus (NV1023) in the treatment of murine SCC VII squamous cell carcinoma. All three viruses demonstrated similar infection efficiency, viral replication, and cytotoxicity in vitro. SCC VII cells infected by NV1034 and NV1042 effectively produced GM-CSF and IL-12, respectively. In an SCC VII subcutaneous flank tumor model in immunocompetent C3H/HeJ mice, intratumoral injection with each virus caused a significant reduction in tumor volume compared with saline injections. The NV1042-treated tumors showed a striking reduction in tumor volume compared with the NV1023- and NV1034-treated tumors. On subsequent rechallenge in the contralateral flank with SCC VII cells, 57% of animals treated with NV1042 failed to develop tumors, in comparison with 14% of animals treated with NV1023 or NV1034, and 0% of naive animals. The increased antitumor efficacy seen with NV1042 in comparison with NV1023 and NV1034 was abrogated by CD4(+) and CD8(+) lymphocyte depletion. NV1042 is a novel, attenuated, oncolytic herpesvirus that effectively expresses IL-12 and elicits a T lymphocyte-mediated antitumor immune response against murine squamous cell carcinoma. Such combined oncolytic and immunomodulatory strategies hold promise in the treatment of cancer.

Vacuole acidification is not required for survival of Salmonella enterica serovar typhimurium within cultured macrophages and epithelial cells

Phagosome acidification is an important component of the microbicidal response by infected eukaryotic cells. Thus, intracellular pathogens that reside within phagosomes must either block phagosome acidification or be able to survive at low pH. In this work, we studied the effect of phagosomal acidification on the survival of intracellular Salmonella enterica serovar Typhimurium in different cell types. Bafilomycin A1, a specific inhibitor of the vacuolar proton-ATPases, was used to block acidification of salmonella-containing vacuoles. We found that in several epithelial cell lines, treatment with bafilomycin A1 had no effect on intracellular survival or replication. Furthermore, although acidification was essential for Salmonella intracellular survival in J774 cultured macrophages, as reported previously (13), it is not essential in other macrophage cell lines. These data suggest that vacuolar acidification may play a role in intracellular survival of salmonellae only under certain conditions and in specific cell types.

Mutations in the fumarylacetoacetate hydrolase gene causing hereditary tyrosinemia type I: overview

Tyrosinemia type I is an inborn error of metabolism caused by a deficiency in the last enzyme of the tyrosine catabolic pathway, fumarylacetoacetate hydrolase (FAH). The disease has been reported worldwide with varying incidence. Recently, there has been considerable progress in identifying mutations in the FAH gene. At present 26 mutations have been reported, all consisting of single base substitutions resulting in 16 amino acid replacements, one silent mutation causing a splicing defect, five nonsense codons, and four putative splicing defects. The location of these mutations is spread over the entire FAH gene, with a particular clustering between amino acid residues 230 and 250. The identification of these mutations in subpopulations and groups at high risk should help in the diagnosis of, and genetic counseling for, HT1. We describe all these 26 mutations reported so far and their implication in diagnosis and carrier detection.

Increased intracellular drug accumulation and complete chemosensitization achieved in multidrug-resistant solid tumors by co-administering valspodar (PSC 833) with sterically stabilized liposomal doxorubicin

We have previously demonstrated that liposome encapsulation of doxorubicin (DOX) can alleviate adverse interactions with non-encapsulated DOX and the cyclosporine multidrug-resistant (MDR) modulator Valspodar. We have now investigated the behavior of different liposomal DOX formulations in MDA435LCC6/MDR-1 human breast cancer solid tumor xenograft models to identify liposome characteristics associated with enhanced therapeutic activity and the mechanism whereby increased chemosensitization is achieved. Toxicity studies incorporating conventional phosphatidylcholine (PC)/cholesterol (chol) and sterically stabilized (polyethylene glycol 2000 [PEG]-containing) formulations of DOX indicated that whereas PC/Chol DOX was approximately 3-fold more toxic in the presence of Valspodar, PEG containing distearoylglycerophosphocholine (DSPC)/Chol DOX was minimally affected. In mice bearing MDR tumors, co-administration of Valspodar and egg phosphocholine (EPC)/Chol DOX resulted in modest MDR modulation and efficacy, whereas the sterically stabilized formulation induced reductions in tumor growth equivalent to that achieved for drug-sensitive tumors treated with non-encapsulated DOX. Pharmacokinetic studies revealed a 2.5-fold increase in plasma DOX area under the curve (AUC) upon co-administration of Valspodar with EPC/Chol DOX whereas no such alterations were observed with the sterically stabilized liposomes. Compared to non-encapsulated DOX combined with Valspodar, improvements in efficacy and toxicity correlated with the extent to which liposomal DOX formulations were able to circumvent pharmacokinetic interactions. Confocal microscopy demonstrated that Valspodar increased cell-associated DOX which correlated with the level of anti-tumor efficacy.

Genotyping of a case of tyrosinaemia type I with normal level of succinylacetone in amniotic fluid

Tyrosinaemia type I is caused by a deficiency of fumarylacetoacetate hydrolase and mainly affects the liver. This disease is characterized by the presence of a high level of succinylacetone. This metabolite has been used for prenatal diagnosis from amniotic fluid samples. One case with a normal level of succinylacetone in amniotic fluid has recently been described (Grenier et al., 1996). Here, we report that this patient is a compound heterozygote for two known mutations: E364X and IVS6-1g-->t. The low level of succinylacetone cannot be explained by these mutations.

Intracellular delivery and antibacterial activity of gentamicin encapsulated in pH-sensitive liposomes

Cell membranes are relatively impermeable to the antibiotic gentamicin, a factor that, along with the toxicity of gentamicin, precludes its use against many important intracellular bacterial infections. Liposomal encapsulation of this drug was used in order to achieve intracellular antibiotic delivery and therefore increase the drug's therapeutic activity against intracellular pathogens. Gentamicin encapsulation in several dipalmitoylphosphatidylcholine (DPPC) and pH-sensitive dioleoylphosphatidylethanolamine (DOPE)-based carrier systems was characterized. To systematically test the antibacterial efficacies of these formulations, a tissue culture assay system was developed wherein murine macrophage-like J774A.1 cells were infected with bacteria and were then treated with encapsulated drug. Of these formulations, DOPE-N-succinyl-DOPE and DOPE-N-glutaryl-DOPE (70:30;mol:mol) containing small amounts of polyethyleneglycol-ceramide showed appreciable antibacterial activities, killing greater than 75% of intracellular vacuole-resident wild-type Salmonella typhimurium compared to the level of killing of the control formulations. These formulations also efficiently eliminated intracellular infections caused by a recombinant hemolysin-expressing S. typhimurium strain and a Listeria monocytogenes strain, both of which escape the vacuole and reside in the cytoplasm. Control non-pH-sensitive liposomal formulations of gentamicin had poor antibacterial activities. A fluorescence resonance energy transfer assay indicated that the efficacious formulations undergo a pH-dependent lipid mixing and fusion event. Intracellular delivery of the fluorescent molecules encapsulated in these formulations was confirmed by confocal fluorescence microscopy and was shown to be dependent on endosomal acidification. This work shows that encapsulation of membrane-impermeative antibiotics in appropriately designed lipid-based delivery systems can enable their use in treating intracellular infections and details the development of a general assay for testing the intracellular delivery of encapsulated drug formulations.

Lysozyme fragmentation induced by gamma-radiolysis

Irradiation of lysozyme in frozen states in the absence of oxygen induces specific fragmentation at defined sites along the backbone chain. This paper localizes radio-fragmentation sites by two methods. First, N-terminal sequencing of radiolysis fragments after separation by SDS-polyacrylamide gel electrophoresis and estimation of their molecular masses. Secondly, after purification of radiolysis fragments by reverse phase-HPLC and determination of their molecular mass by electro-spray-ionization mass-spectrometric analysis, combined to N-terminal sequencing and total amino acid analysis. Evidence for the breakage of the peptide bond itself (CO-NH) is given, with radio-fragmentation sites mostly found at the surface of irradiated lysozyme in solvent exposed loops and turns.

Tyrosine and its catabolites: from disease to cancer

Hereditary tyrosinemia type I (HT I, McKusick 276,700) is a metabolic disease with a pattern of autosomal recessive inheritance. The disease is caused by a deficiency of the enzyme involved in the last step in the degradation of the amino acid tyrosine, fumarylacetoacetate hydrolase (FAH). The result of this block is the accumulation of catabolites some of which have been proposed to be highly toxic due to their alkylating potential. In humans, hereditary tyrosinemia is often associated with the development of hepatocellular carcinoma in young patients. The reasons for the high incidence of hepatocellular carcinoma are unknown but it has been suggested that it may be caused by accumulated metabolites such as fumarylacetoacetate (FAA) and maleylacetoacetate (MAA). The various mutational defects in the FAH gene are reviewed. The use of two mouse models of this disease to study the molecular basis of the pathologies associated with HT I are discussed. Finally, some preliminary data on the mutagenic potential of FAA and MAA in a gene reversal assay are presented.

Frequency of the IVS12 + 5G-->A splice mutation of the fumarylacetoacetate hydrolase gene in carriers of hereditary tyrosinaemia in the French Canadian population of Saguenay-Lac-St-Jean

Hereditary tyrosinaemia type I (HTI), an autosomal recessive inborn error of metabolism, is caused by a deficiency of the enzyme fumarylacetoacetate hydrolase. The highest incidence of HTI is observed in the Saguenay-Lac-St-Jean region (SLSJ) (Québec, Canada), where 1 out of 22 individuals is thought to be a carrier. A splice mutation (IVS12 + 5G-->A) has recently been identified in this particular region. Here, we have determined the frequency of this mutation in a population of obligate carriers from the SLSJ region by allele-specific oligonucleotide hybridization and a method using a restriction enzyme digestion. Over 95 per cent of the HTI carriers were found to have the IVS12 + 5G-->A splice mutation. Screening for this mutation based on the two methods reported here is thus a reliable and rapid way of detecting carriers of hereditary tyrosinaemia type I in that region at high risk.

HTLV-I infection among prostitutes and pregnant women in Kinshasa, Zaïre: how important is high-risk sexual behavior?

High-risk sexual behavior as risk factor for human T-cell lymphotropic virus type I (HTLV-I) infection was assessed in cross-sectional studies with 1,183 prostitutes and 1,166 pregnant women in Kinshasa, Zaire. Eighty six (7.3%) prostitutes were positive for HTLV-I. The seroprevalence among prostitutes from the regions along the equator was 12.7%, whereas among prostitutes from the other regions it ranged between 0 and 4.3%. In the prostitutes from the high-prevalence regions, but not in the prostitutes from the low-prevalence regions, HTLV-I infection was associated with increasing age [odds ratio (OR) = 1.1 per year increment], active syphilis (OR = 2.3), and human immunodeficiency virus (HIV) infection (OR = 2.0). Forty three (3.7%) pregnant women were HTLV-I seropositive. Among the women from low-prevalence regions, there was no significant difference in HTLV-I seroprevalence between prostitutes (4.3%) and pregnant women (3.5%). In a group of 409 prostitutes who were observed for a mean duration of 23 months, the incidence of HTLV-I infection was 0.7 per 100 women-years, whereas the incidence of HIV infection was 9.8 per 100 women-years. We conclude that in Kinshasa prostitution per se was not associated with an increased risk of HTLV-I infection.

A single mutation of the fumarylacetoacetate hydrolase gene in French Canadians with hereditary tyrosinemia type I

BACKGROUND

Hereditary tyrosinemia type I is an autosomal recessive inborn error of metabolism caused by a deficiency of the enzyme fumarylacetoacetate hydrolase. The disorder clusters in the Saguenay-Lac-St.-Jean area of Quebec. In this region, 1 of 1846 newborns is affected and 1 of every 22 persons is thought to be a carrier. Recently, we identified a splice mutation and two nonsense mutations in the fumarylacetoacetate hydrolase gene in two patients from Quebec with tyrosinemia type I.

METHODS

We used allele-specific-oligonucleotide hybridization to examine the frequency of these three candidate mutations in patients with tyrosinemia type I and in the population of Quebec.

RESULTS

The splice mutation was found in 100 percent of patients from the Saguenay-Lac-St.-Jean area and in 28 percent of patients from other regions of the world. Of 25 patients from the Saguenay-Lac-St.-Jean region, 20 (80 percent) were homozygous for this mutation, a guanine-to-adenine change in the splice-donor sequence in intron 12 of the gene, indicating that it causes most cases of tyrosinemia type I in the region. The frequency of carrier status, based on screening of blood spots from newborns, was about 1 per 25 in the Saguenay-Lac-St.-Jean population and about 1 per 66 overall in Quebec.

CONCLUSIONS

This study identified the most prevalent mutation causing hereditary tyrosinemia in French Canada; it also showed the feasibility of DNA-based testing for carriers in the population at risk.

Identification of a stop mutation in five Finnish patients suffering from hereditary tyrosinemia type I

Hereditary tyrosinemia type I is a metabolic disease caused by a deficiency of fumarylacetoacetate hydrolase (FAH, EC 3.7.1.2), the last enzyme in the catabolic pathway of tyrosine. The molecular basis of FAH deficiency was examined in five Finnish patients suffering from this severe metabolic disease. No immunoreactive FAH nor enzymatic activity were found in their liver. Direct sequencing of the 14 exons of the FAH gene showed a G to A transition, which predicts a change from tryptophan to a stop codon (TGG-->TGA) at position 262 (W262X). Four of the five patients examined were homozygous for the mutation. Allele specific oligonucleotide hybridization showed a predominance of the W262X mutation in Finland (9 of 10 alleles) and the absence of this mutant allele in patients from other parts of the world. The loss of a BsaJI restriction site in those patients may be used for diagnosis.