The serum small non-coding RNA (SncRNA) landscape as a molecular biomarker of age associated muscle dysregulation and insulin resistance in older adults

Small noncoding RNAs (sncRNAs) are implicated in age-associated pathologies, including sarcopenia and insulin resistance (IR). As potential circulating biomarkers, most studies have focussed on microRNAs (miRNAs), one class of sncRNA. This study characterized the wider circulating sncRNA transcriptome of older individuals and associations with sarcopenia and IR. sncRNA expression including miRNAs, transfer RNAs (tRNAs), tRNA-associated fragments (tRFs), and piwi-interacting RNAs (piRNAs) was measured in serum from 21 healthy and 21 sarcopenic Hertfordshire Sarcopenia Study extension women matched for age (mean 78.9 years) and HOMA2-IR. Associations with age, sarcopenia and HOMA2-IR were examined and predicted gene targets and biological pathways characterized. Of the total sncRNA among healthy controls, piRNAs were most abundant (85.3%), followed by tRNAs (4.1%), miRNAs (2.7%), and tRFs (0.5%). Age was associated (FDR < 0.05) with 2 miRNAs, 58 tRNAs, and 14 tRFs, with chromatin organization, WNT signaling, and response to stress enriched among gene targets. Sarcopenia was nominally associated (p < .05) with 12 tRNAs, 3 tRFs, and 6 piRNAs, with target genes linked to cell proliferation and differentiation such as Notch Receptor 1 (NOTCH1), DISC1 scaffold protein (DISC1), and GLI family zinc finger-2 (GLI2). HOMA2-IR was nominally associated (p<0.05) with 6 miRNAs, 9 tRNAs, 1 tRF, and 19 piRNAs, linked with lysine degradation, circadian rhythm, and fatty acid biosynthesis pathways. These findings identify changes in circulating sncRNA expression in human serum associated with chronological age, sarcopenia, and IR. These may have clinical utility as circulating biomarkers of ageing and age-associated pathologies and provide novel targets for therapeutic intervention.

DNA methylation of insulin signaling pathways is associated with HOMA2-IR in primary myoblasts from older adults

BACKGROUND

While ageing is associated with increased insulin resistance (IR), the molecular mechanisms underlying increased IR in the muscle, the primary organ for glucose clearance, have yet to be elucidated in older individuals. As epigenetic processes are suggested to contribute to the development of ageing-associated diseases, we investigated whether differential DNA methylation was associated with IR in human primary muscle stem cells (myoblasts) from community-dwelling older individuals.

METHODS

We measured DNA methylation (Infinium HumanMethylationEPIC BeadChip) in myoblast cultures from vastus lateralis biopsies (119 males/females, mean age 78.24 years) from the Hertfordshire Sarcopenia Study extension (HSSe) and examined differentially methylated cytosine phosphate guanine (CpG) sites (dmCpG), regions (DMRs) and gene pathways associated with HOMA2-IR, an index for the assessment of insulin resistance, and levels of glycated hemoglobin HbA1c.

RESULTS

Thirty-eight dmCpGs (false discovery rate (FDR) < 0.05) were associated with HOMA2-IR, with dmCpGs enriched in genes linked with JNK, AMPK and insulin signaling. The methylation signal associated with HOMA2-IR was attenuated after the addition of either BMI (6 dmCpGs), appendicular lean mass index (ALMi) (7 dmCpGs), grip strength (15 dmCpGs) or gait speed (23 dmCpGs) as covariates in the model. There were 8 DMRs (Stouffer < 0.05) associated with HOMA2-IR, including DMRs within T-box transcription factor (TBX1) and nuclear receptor subfamily-2 group F member-2 (NR2F2); the DMRs within TBX1 and NR2F2 remained associated with HOMA2-IR after adjustment for BMI, ALMi, grip strength or gait speed. Forty-nine dmCpGs and 21 DMRs were associated with HbA1c, with cg13451048, located within exoribonuclease family member 3 (ERI3) associated with both HOMA2-IR and HbA1c. HOMA2-IR and HbA1c were not associated with accelerated epigenetic ageing.

CONCLUSIONS

These findings suggest that insulin resistance is associated with differential DNA methylation in human primary myoblasts with both muscle mass and body composition making a significant contribution to the methylation changes associated with IR.

Adiposity is associated with widespread transcriptional changes and downregulation of longevity pathways in aged skeletal muscle

BACKGROUND

Amongst healthy older people, a number of correlates of impaired skeletal muscle mass and function have been defined. Although the prevalence of obesity is increasing markedly in this age group, information is sparse about the particular impacts of obesity on ageing skeletal muscle or the molecular mechanisms that underlie this and associated disease risk.

METHODS

Here, we examined genome-wide transcriptional changes using RNA sequencing in muscle biopsies from 40 older community-dwelling men from the Hertfordshire Sarcopenia Study with regard to obesity (body mass index [BMI] >30 kg/m2 , n = 7), overweight (BMI 25-30, n = 19), normal weight (BMI < 25, n = 14), and per cent and total fat mass. In addition, we used EPIC DNA methylation array data to investigate correlations between DNA methylation and gene expression in aged skeletal muscle tissue and investigated the relationship between genes within altered regulatory pathways and muscle histological parameters.

RESULTS

Individuals with obesity demonstrated a prominent modified transcriptional signature in muscle tissue, with a total of 542 differentially expressed genes associated with obesity (false discovery rate ≤0.05), of which 425 genes were upregulated when compared with normal weight. Upregulated genes were enriched in immune response (P = 3.18 × 10-41 ) and inflammation (leucocyte activation, P = 1.47 × 10-41 ; tumour necrosis factor, P = 2.75 × 10-15 ) signalling pathways and downregulated genes enriched in longevity (P = 1.5 × 10-3 ) and AMP-activated protein kinase (AMPK) (P = 4.5 × 10-3 ) signalling pathways. Furthermore, differentially expressed genes in both longevity and AMPK signalling pathways were associated with a change in DNA methylation, with a total of 256 and 360 significant cytosine-phosphate-guanine-gene correlations identified, respectively. Similar changes in the muscle transcriptome were observed with respect to per cent fat mass and total fat mass. Obesity was further associated with a significant increase in type II fast-fibre area (P = 0.026), of which key regulatory genes within both longevity and AMPK pathways were significantly associated.

CONCLUSIONS

We provide for the first time a global transcriptomic profile of skeletal muscle in older people with and without obesity, demonstrating modulation of key genes and pathways implicated in the regulation of muscle function, changes in DNA methylation associated with such pathways and associations between genes within the modified pathways implicated in muscle regulation and changes in muscle fibre type.

Alzheimer's disease amyloid-β pathology in the lens of the eye

Neuropathological hallmarks of Alzheimer's disease (AD) include pathogenic accumulation of amyloid-β (Aβ) peptides and age-dependent formation of amyloid plaques in the brain. AD-associated Aβ neuropathology begins decades before onset of cognitive symptoms and slowly progresses over the course of the disease. We previously reported discovery of Aβ deposition, β-amyloidopathy, and co-localizing supranuclear cataracts (SNC) in lenses from people with AD, but not other neurodegenerative disorders or normal aging. We confirmed AD-associated Aβ molecular pathology in the lens by immunohistopathology, amyloid histochemistry, immunoblot analysis, epitope mapping, immunogold electron microscopy, quantitative immunoassays, and tryptic digest mass spectrometry peptide sequencing. Ultrastructural analysis revealed that AD-associated Aβ deposits in AD lenses localize as electron-dense microaggregates in the cytoplasm of supranuclear (deep cortex) fiber cells. These Aβ microaggregates also contain αB-crystallin and scatter light, thus linking Aβ pathology and SNC phenotype expression in the lenses of people with AD. Subsequent research identified Aβ lens pathology as the molecular origin of the distinctive cataracts associated with Down syndrome (DS, trisomy 21), a chromosomal disorder invariantly associated with early-onset Aβ accumulation and Aβ amyloidopathy in the brain. Investigation of 1249 participants in the Framingham Eye Study found that AD-associated quantitative traits in brain and lens are co-heritable. Moreover, AD-associated lens traits preceded MRI brain traits and cognitive deficits by a decade or more and predicted future AD. A genome-wide association study of bivariate outcomes in the same subjects identified a new AD risk factor locus in the CTNND2 gene encoding δ-catenin, a protein that modulates Aβ production in brain and lens. Here we report identification of AD-related human Aβ (hAβ) lens pathology and age-dependent SNC phenotype expression in the Tg2576 transgenic mouse model of AD. Tg2576 mice express Swedish mutant human amyloid precursor protein (APP-Swe), accumulate hAβ peptides and amyloid pathology in the brain, and exhibit cognitive deficits that slowly progress with increasing age. We found that Tg2576 trangenic (Tg⁺) mice, but not non-transgenic (Tg^-) control mice, also express human APP, accumulate hAβ peptides, and develop hAβ molecular and ultrastructural pathologies in the lens. Tg2576 Tg⁺ mice exhibit age-dependent Aβ supranuclear lens opacification that recapitulates lens pathology and SNC phenotype expression in human AD. In addition, we detected hAβ in conditioned medium from lens explant cultures prepared from Tg⁺ mice, but not Tg^- control mice, a finding consistent with constitutive hAβ generation in the lens. In vitro studies showed that hAβ promoted mouse lens protein aggregation detected by quasi-elastic light scattering (QLS) spectroscopy. These results support mechanistic (genotype-phenotype) linkage between Aβ pathology and AD-related phenotypes in lens and brain. Collectively, our findings identify Aβ pathology as the shared molecular etiology of two age-dependent AD-related cataracts associated with two human diseases (AD, DS) and homologous murine cataracts in the Tg2576 transgenic mouse model of AD. These results represent the first evidence of AD-related Aβ pathology outside the brain and point to lens Aβ as an optically-accessible AD biomarker for early detection and longitudinal monitoring of this devastating neurodegenerative disease.

Epigenome-wide association study of sarcopenia: findings from the Hertfordshire Sarcopenia Study (HSS)

BACKGROUND

Sarcopenia is the age-related loss of muscle mass, strength, and function. Epigenetic processes such as DNA methylation, which integrate both genetic and environmental exposures, have been suggested to contribute to the development of sarcopenia. This study aimed to determine whether differences in the muscle methylome are associated with sarcopenia and its component measures: grip strength, appendicular lean mass index (ALMi), and gait speed.

METHODS

Using the Infinium Human MethylationEPIC BeadChip, we measured DNA methylation in vastus lateralis muscle biopsies of 83 male participants (12 with sarcopenia) with a mean (standard deviation) age of 75.7 (3.6) years from the Hertfordshire Sarcopenia Study (HSS) and Hertfordshire Sarcopenia Study extension (HSSe) and examined associations with sarcopenia and its components. Pathway, histone mark, and transcription factor enrichment of the differentially methylated CpGs (dmCpGs) were determined, and sodium bisulfite pyrosequencing was used to validate the sarcopenia-associated dmCpGs. Human primary myoblasts (n = 6) isolated from vastus lateralis muscle biopsies from male individuals from HSSe were treated with the EZH2 inhibitor GSK343 to assess how perturbations in epigenetic processes may impact myoblast differentiation and fusion, measured by PAX7 and MYHC immunocytochemistry, and mitochondrial bioenergetics determined using the Seahorse XF96.

RESULTS

Sarcopenia was associated with differential methylation at 176 dmCpGs (false discovery rate ≤ 0.05) and 141 differentially methylated regions (Stouffer ≤ 0.05). The sarcopenia-associated dmCpGs were enriched in genes associated with myotube fusion (P = 1.40E-03), oxidative phosphorylation (P = 2.78E-02), and voltage-gated calcium channels (P = 1.59E-04). ALMi was associated with 71 dmCpGs, grip strength with 49 dmCpGs, and gait speed with 23 dmCpGs (false discovery rate ≤ 0.05). There was significant overlap between the dmCpGs associated with sarcopenia and ALMi (P = 3.4E-35), sarcopenia and gait speed (P = 4.78E-03), and sarcopenia and grip strength (P = 7.55E-06). There was also an over-representation of the sarcopenia, ALMi, grip strength, and gait speed-associated dmCpGs with sites of H3K27 trimethylation (all P ≤ 0.05) and amongst EZH2 target genes (all P ≤ 0.05). Furthermore, treatment of human primary myoblasts with the EZH2 inhibitor GSK343 inhibitor led to an increase in PAX7 expression (P ≤ 0.05), decreased myotube fusion (P = 0.043), and an increase in ATP production (P = 0.008), with alterations in the DNA methylation of genes involved in oxidative phosphorylation and myogenesis.

CONCLUSIONS

These findings show that differences in the muscle methylome are associated with sarcopenia and individual measures of muscle mass, strength, and function in older individuals. This suggests that changes in the epigenetic regulation of genes may contribute to impaired muscle function in later life.

High maternal folic acid intake around conception alters mouse blastocyst lineage allocation and expression of key developmental regulatory genes

Folate, a cofactor for the supply of one-carbon groups, is required by epigenetic processes to regulate cell lineage determination during development. The intake of folic acid (FA), the synthetic form of folate, has increased significantly over the past decade, but the effects of high periconceptional FA intake on cell lineage determination in the early embryo remains unknown. Here, we investigated the effect of maternal high FA (HFA) intake on blastocyst development and expression of key regulatory genes. C57BL/6 adult female mice were fed either Control diet (1 mg FA) for 4 weeks before conception and during the preimplantation period (Con-Con); Control diet for 4 weeks preconception, followed by HFA (5 mg FA) diet during preimplantation (Con-HFA); or HFA diet for 4 weeks preconception and during preimplantation (HFA-HFA). At E3.5, blastocyst cell number, protein, and mRNA expression were measured. In HFA-HFA blastocysts, trophectoderm cell numbers and expression of CDX2, Oct-4, and Nanog were reduced compared with Con-Con blastocysts; Con-HFA blastocysts showed lower CDX2 and Oct-4 expression than Con-Con blastocysts. These findings suggest periconceptional HFA intake induces changes in key regulators of embryo morphogenesis with potential implications for subsequent development.

The structure of ScC2 (X̃2A1): A combined Fourier transform microwave/millimeter-wave spectroscopic and computational study

Pure rotational spectra of Sc¹³C₂ (X̃²A₁) and Sc¹²C¹³C (X̃²A') have been measured using Fourier transform microwave/millimeter-wave methods. These molecules were synthesized in a DC discharge from the reaction of scandium vapor, produced via laser ablation, with ¹³CH₄ or ¹³CH₄/¹²CH₄, diluted in argon. The N_Ka,Kc = 1_0,1 → 0_0,0, 2_0,2 → 1_0,1, 3_0,3 → 2_0,2, and 4_0,4 → 3_0,3 transitions in the frequency range of 14 GHz-61 GHz were observed for both species, each exhibiting hyperfine splittings due to the nuclear spins of ¹³C (I = 1/2) and/or Sc (I = 7/2). These data have been analyzed with an asymmetric top Hamiltonian, and rotational, spin-rotation, and hyperfine parameters have been determined for Sc¹³C₂ and Sc¹²C¹³C. In addition, a quartic force field was calculated for ScC₂ and its isotopologues using a highly accurate coupled cluster-based composite method, incorporating complete basis set extrapolation, scalar relativistic corrections, outer core and inner core electron correlation, and higher-order valence correlation effects. The agreement between experimental and computed rotational constants, including the effective constant (B + C), is ∼0.5% for all three isotopologues. This remarkable agreement suggests promise in predicting rotational spectra of new transition metal-carbon bearing molecules. In combination with previous work on Sc¹²C₂, an accurate structure for ScC₂ has been established using combined experimental (B, C) and theoretical (A) rotational constants. The radical is cyclic (or T-shaped) with r_(Sc-C) = 2.048(2) Å, r_(C-C) = 1.272(2) Å, and ∠_(C-Sc-C) = 36.2(1)°. The experimental and theoretical results also suggest that ScC₂ contains a C₂ ^- moiety and is largely ionic.

The ground state of KO revisited: the millimeter and submillimeter spectrum of potassium oxide

The millimeter/sub-millimeter spectrum of the KO radical has been recorded in the frequency range 90-534 GHz using direct absorption methods. The radical was synthesized by reacting potassium vapor, produced with a Broida-type oven, with either N2O or O2 mixed in argon carrier gas. Twenty-seven rotational transitions of KO were measured, each exhibiting a doublet structure with a relatively small splitting (∼100-200 MHz) that increased noticeably with frequency. A perturbation was apparent in the rotational lines at energies above ∼120 cm-1, which was more prominent in one doublet component. The data were successfully fit with a Hund's case (c) Hamiltonian, assuming that spectra arise from a 2Πi state, and rotational and effective lambda-doubling constants were determined. Higher order centrifugal distortion terms were needed to account for the perturbation. The spectra could also be fit as a 2Σ+ ground state, but less successfully, and the resulting rotational constant of B = 8235.4 MHz disagreed significantly with that predicted by theory. On the basis of the experimental data, the ground electronic state of KO has been assigned as 2Πi, although the 2Σ+ assignment cannot be entirely ruled out.

Nutritional modulation of the epigenome and its implication for future health

Non-communicable diseases (NCD) such as type-2 diabetes and CVD are now highly prevalent in both developed and developing countries. Evidence from both human and animal studies shows that early-life nutrition is an important determinant of NCD risk in later life. The mechanism by which the early-life environment influences future disease risk has been suggested to include the altered epigenetic regulation of gene expression. Epigenetic processes regulate the accessibility of genes to the cellular proteins that control gene transcription, determining where and when a gene is switched on and its level of activity. Epigenetic processes not only play a central role in regulating gene expression but also allow an organism to adapt to the environment. In this review, we will focus on how both maternal and paternal nutrition can alter the epigenome and the evidence that these changes are causally involved in determining future disease risk.

The pure rotational spectrum of the ZnBr radical (X2Σ+): Trends in the zinc halide series

The pure rotational spectrum of ZnBr (X²Σ⁺) has been recorded in the frequency range 259-310 GHz using millimeter-wave direct absorption techniques. This study is the first quantitative spectroscopic investigation of this free radical. ZnBr was synthesized in a DC discharge by the reaction of zinc vapor in argon with one of three reagents: BrCH₃, Br₂CH₂, or Br₂. Eight rotational transitions were measured for six isotopologues (⁶⁴Zn⁷⁹Br, ⁶⁴Zn⁸¹Br, ⁶⁶Zn⁷⁹Br, ⁶⁶Zn⁸¹Br, ⁶⁸Zn⁷⁹Br, and ⁶⁸Zn⁸¹Br), all of which exhibited spin-rotation interactions. Furthermore, transitions originating in the v = 1 through 3 excited vibrational states were obtained for certain isotopologues. Five rotational transitions were also recorded for ⁶⁷Zn⁷⁹Br, in which hyperfine splittings were observed arising from the ⁶⁷Zn nucleus (I = 5/2). The spectra were analyzed using a Hund's case (b_βJ) Hamiltonian, and rotational, spin-rotation, and ⁶⁷Zn magnetic hyperfine constants were determined. Equilibrium parameters were also derived for the ⁶⁴Zn⁷⁹Br, ⁶⁴Zn⁸¹Br, ⁶⁶Zn⁷⁹Br, and ⁶⁶Zn⁸¹Br isotopologues, including the vibrational constant, ω_e = 286 cm^-1. The equilibrium bond length was derived to be r_e = 2.268 48(90) Å. Analysis of the ⁶⁷Zn hyperfine parameters suggest a decrease in ionic character in ZnBr from the other known zinc halides, ZnF and ZnCl.

Evaluation of Ion-exchange Microspheres as Carriers for the Anticancer Drug Doxorubicin: In-vitro Studies

A comparison study of doxorubicin loading, release characteristics and stability within sodium and hydrogen forms of ion-exchange resin microspheres has been performed. It was demonstrated that resins in the Na+ form, although having lower drug loading capacity, showed similar release profiles to resins in the H+ form but still maintain all the drug activity. Resins in the H+ form, despite having high drug loading capacity, caused drug degradation within microspheres due to their strong acidic nature. Therefore, in comparison with the H+ form, resins in the Na+ form can be considered as better carriers for doxorubicin in terms of sustaining the release of drug and maintaining drug activity. Other factors such as the degree of resin cross-linkage and drug/resin mixing time have also been examined in relation to drug loading and release characteristics. Overall, this study demonstrated the significance of the characteristics of matrix materials and their influence on the drug activity and microsphere performance in-vitro.

Alzheimer's disease amyloid-beta links lens and brain pathology in Down syndrome

Down syndrome (DS, trisomy 21) is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans. In DS, triplication of chromosome 21 invariably includes the APP gene (21q21) encoding the Alzheimer's disease (AD) amyloid precursor protein (APP). Triplication of the APP gene accelerates APP expression leading to cerebral accumulation of APP-derived amyloid-beta peptides (Abeta), early-onset AD neuropathology, and age-dependent cognitive sequelae. The DS phenotype complex also includes distinctive early-onset cerulean cataracts of unknown etiology. Previously, we reported increased Abeta accumulation, co-localizing amyloid pathology, and disease-linked supranuclear cataracts in the ocular lenses of subjects with AD. Here, we investigate the hypothesis that related AD-linked Abeta pathology underlies the distinctive lens phenotype associated with DS. Ophthalmological examinations of DS subjects were correlated with phenotypic, histochemical, and biochemical analyses of lenses obtained from DS, AD, and normal control subjects. Evaluation of DS lenses revealed a characteristic pattern of supranuclear opacification accompanied by accelerated supranuclear Abeta accumulation, co-localizing amyloid pathology, and fiber cell cytoplasmic Abeta aggregates (approximately 5 to 50 nm) identical to the lens pathology identified in AD. Peptide sequencing, immunoblot analysis, and ELISA confirmed the identity and increased accumulation of Abeta in DS lenses. Incubation of synthetic Abeta with human lens protein promoted protein aggregation, amyloid formation, and light scattering that recapitulated the molecular pathology and clinical features observed in DS lenses. These results establish the genetic etiology of the distinctive lens phenotype in DS and identify the molecular origin and pathogenic mechanism by which lens pathology is expressed in this common chromosomal disorder. Moreover, these findings confirm increased Abeta accumulation as a key pathogenic determinant linking lens and brain pathology in both DS and AD.

Activity pattern and personal exposure to nitrogen dioxide in indoor and outdoor microenvironments

People are exposed to air pollution from a range of indoor and outdoor sources. Concentrations of nitrogen dioxide (NO(2)), which is hazardous to health, can be significant in both types of environments. This paper reports on the measurement and analysis of indoor and outdoor NO(2) concentrations and their comparison with measured personal exposure in various microenvironments during winter and summer seasons. Furthermore, the relationship between NO(2) personal exposure in various microenvironments and including activities patterns were also studied. Personal, indoor microenvironments and outdoor measurements of NO(2) levels were conducted using Palmes tubes for 60 subjects. The results showed significant differences in indoor and outdoor NO(2) concentrations in winter but not for summer. In winter, indoor NO(2) concentrations were found to be strongly correlated with personal exposure levels. NO(2) concentration in houses using a gas cooker was higher in all rooms than those with an electric cooker during the winter campaign, whereas there was no significant difference noticed in summer. The average NO(2) levels in kitchens with a gas cooker were twice as high as those with an electric cooker, with no significant difference in the summer period. A time-weighted average personal exposure was calculated and compared with measured personal exposures in various indoor microenvironments (e.g. front doors, bedroom, living room and kitchen); including non-smokers, passive smokers and smoker. The estimated results were closely correlated, but showed some underestimation of the measured personal exposures to NO(2) concentrations. Interestingly, for our particular study higher NO(2) personal exposure levels were found during summer (14.0+/-1.5) than winter (9.5+/-2.4).

Rural oral health workforce issues in NSW and the Charles Sturt University Dentistry Program

Adequate numbers of dental, medical and allied health professionals in rural and regional areas of NSW are vital for the health of these populations and supporting local community structures and economies. Well-documented shortages of health professionals are a major social and political issue in rural and regional communities and this workforce shortfall is recognised by both the NSW Government State Plan and the State Health Plan. This paper outlines rural and regional dental workforce shortages in NSW and describes current rural oral health workforce initiatives, including the new Charles Sturt University Dentistry Program.

Increased tumor localization and reduced immune response to adenoviral vector formulated with the liposome DDAB/DOPE

We aimed to increase the efficiency of adenoviral vectors by limiting adenoviral spread from the target site and reducing unwanted host immune responses to the vector. We complexed adenoviral vectors with DDAB-DOPE liposomes to form adenovirus-liposomal (AL) complexes. AL complexes were delivered by intratumoral injection in an immunocompetent subcutaneous rat tumor model and the immunogenicity of the AL complexes and the expression efficiency in the tumor and other organs was examined. Animals treated with the AL complexes had significantly lower levels of beta-galactosidase expression in systemic tissues compared to animals treated with the naked adenovirus (NA) (P<0.05). The tumor to non-tumor ratio of beta-galactosidase marker expression was significantly higher for the AL complex treated animals. NA induced significantly higher titers of adenoviral-specific antibodies compared to the AL complexes (P<0.05). The AL complexes provided protection (immunoshielding) to the adenovirus from neutralizing antibody. Forty-seven percent more beta-galactosidase expression was detected following intratumoral injection with AL complexes compared to the NA in animals pre-immunized with adenovirus.

CONCLUSIONS

Complexing of adenovirus with liposomes provides a simple method to enhance tumor localization of the vector, decrease the immunogenicity of adenovirus, and provide protection of the virus from pre-existing neutralizing antibodies.

Development of polysaccharide gel coated pellets for oral administration

Spherical pellets containing theophylline, calcium acetate and microcrystalline cellulose were extruded and spheronized, before being coated with six different pectins or alginates by interfacial complexation. The aim of this study was to discover the effect of the coatings on physico-mechanical properties that will be crucial in determining the pellets' utility as sustained release systems. An insoluble, smooth and uniformly thick coat of calcium polysaccharide was formed around the core pellets. A factorial experiment was designed to investigate the effect of pellet size and polysaccharide type and concentration on the entrapment efficiency, mechanical properties and other physical characteristics. Coated pellets were observed by scanning electron microscopy and, depending on the particular polysaccharide used, the dry coats were found to be 30-80 microm thick. The size of pellet, the type and concentration of polysaccharide influenced the yield of theophylline in the coated pellets. Although the mechanical properties of the pellets were improved by applying any of the gel coats, use of an alginate with a high content of guluronic acid or an amidated pectin coating gave the best results. This is probably because both of these have significant potential to form very stable cross-links within the gel coats.

Modification of liposomal concentration in liposome/adenoviral complexes allows significant protection of adenoviral vectors from neutralising antibody, in vitro

Adenoviral vectors have been commonly used in gene therapy protocols, however the success of their use is often limited by the induction of host immunity to the vector. Following exposure to the adenoviral vector, adenoviral-specific neutralising antibodies are produced which limits further administration. This study examines the efficacy of complexing liposomes to adenovirus for the protection of the adenovirus from neutralising antibodies in an in vitro setting. Dimethyldioctadecylammonium bromide (DDAB)-dioleoyl-l-phosphatidylethanolamine (DOPE) liposomes were bound at varying concentrations to adenovirus to form AL complexes and tested these complexes' ability to prevent adenoviral neutralisation. It is shown that by increasing the concentration of liposomes in the adenoviral-liposome (AL) complexes we can increase the level of immuno-shielding afforded the adenovirus. It is also shown that the increase in liposomal concentration may lead to drawbacks such as increased cytotoxicity and reductions in expression levels.

Microsphere-liposome complexes protect adenoviral vectors from neutralising antibody without losses in transfection efficiency, in-vitro

Adenoviral vectors have been commonly used in gene therapy protocols but the success of their use is often limited by the induction of host immunity to the vector. Following exposure to the adenoviral vector, adenoviral-specific neutralising antibodies are produced, which limits further administration. This study examines the effectiveness of a novel combination of microspheres and liposomes for the shielding of adenovirus from neutralising antibodies in an in-vitro setting. We show that liposomes are effective in the protection of adenovirus from neutralising antibody and that the conjugation of these complexes to microspheres augments the level of protection. This study further reveals that previously neutralised adenovirus may still be transported into the cell via liposome-cell interactions and is still capable of expressing its genes, making this vector an effective tool for circumvention of the humoral immune response. We also looked at possible side effects of using the complexes, namely increases in cytotoxicity and reductions in transfection efficiency. Our results showed that varying the liposome:adenovirus ratio can reduce the cytotoxicity of the vector as well as increase the transfection efficiency. In addition, in cell lines that are adenoviral competent, transfection efficiencies on par with uncomplexed adenoviral vectors were achievable with the combination vector.

Respiratory function testing: the impact of respiratory scientists on the training and support of primary health care providers

OBJECTIVE

In rural Australia access to doctors is limited, access to respiratory physicians even more so and these are the traditional sources of lung function testing. The aim of this study was to assess the feasibility of training and supporting existing rural primary healthcare providers in lung function testing as a screening and monitoring mechanism due to the shortage of healthcare professionals capable of providing such a service.

METHODOLOGY

As pharmacists are readily accessible healthcare professionals, they were trained in spirometry measurement and supported with ongoing quality assurance by respiratory scientists. Spirometers were provided to the pharmacists. People purchasing respiratory medications or responding to advertising about the service were tested after giving informed consent. Spirometic assessments were assessed for accuracy and reproducibility. Participants' spirometry results were reviewed and those with abnormal test results were referred to their doctor.

RESULTS

Pharmacists were able to competently develop the skills necessary for providing spirometry measurement as a screening and monitoring technique. The level of competence exceeded that reported in previously published studies. Pharmacists were able to successfully identify spirometry results within the normal range.

CONCLUSIONS

Training and supporting accessible healthcare professionals to provide lung function testing increases access in areas of need and has implications for respiratory morbidity and mortality in such settings.

In-vitro evaluation of ion-exchange microspheres for the sustained release of liposomal–adenoviral conjugates

This study looks at the development of a novel combination vector consisting of adenovirus conjugated to liposomes (AL complexes) bound to cation-exchanging microspheres (MAL complexes). With adenovirus having a net negative charge and the liposomes a net positive charge it was possible to modify the net charge of the AL complexes by varying the concentrations of adenovirus to liposomes. The modification of the net charge resulted in altered binding and release characteristics. Of the complexes tested, the 5:1 and 2:1 ratio AL complexes were able to be efficiently bound by the microspheres and exhibited sustained release over 24 h. The 1:1 and 1:2 AL complexes, however, bound poorly to the microspheres and were rapidly released. In addition the MAL complexes also were able to reduce the toxicity of the AL complexes, which was seen with the 10:1 ratio. The AL complexes showed considerably more toxicity alone than in combination with microspheres, highlighting a potential benefit of this vector.

Pre-treatment with a non-therapeutic dose of cisplatin increases solid tumour response to liposomal-p53 gene therapy- An in vivo study

Successful liposomal-mediated gene therapy is often limited by poor transfection efficiencies. One method previously shown to increase the efficiency of liposomal gene delivery is through the administration of a non-therapeutic dose of the chemotherapeutic drug cisplatin prior to lipofection. The currents study aims to utilise this method to deliver lipoplexes containing the p53 tumour suppressor gene with the aim of increasing therapeutic effect of the p53 gene on a solid tumour in vivo. Rats, implanted with solid salivary adenocarcinomas, were pre-treated with a low dose of cisplatin seven days prior to liposomal mediated p53 treatment. Following treatment with p53, tumour growth, p53 expression and levels of apoptosis were examined and compared to animals treated with p53 without cisplatin pre-treatment and a saline control. Tumours that had been pre-treated with cisplatin prior to p53-lipofection were significantly smaller than both the saline control and the non-cisplatin treated tumours. Saline treated tumours increased in size by an average of 164% over a 96-hour period compared to 64% and 101% for the cisplatin and non-cisplatin p53-liposome treated tumours. The cisplatin pre-treated tumours resulted in significantly higher levels of apoptosis surrounding the treatment site and exhibited prolonged p53 expression when compared to the non-cisplatin pre-treated tumours. The results suggest that the use of cisplatin to pre-sensitise tumours to lipofection has significant benefits when used in conjunction with p53.

Modified microplex vector enhances transfection of cells in culture while maintaining tumour-selective gene delivery in-vivo

A non-commercial liposome (dimethyl dioctadecyl ammonium bromide:dioleoyl phosphatidylethanolamine) was compared with a commercial variety (Lipofectamine) for transfection of cultured rat adenocarcinoma cells and in an in-vivo kidney tumour model. Transfection of the cells in culture and in tumours in-vivo was variable with both types of liposomes. A high-dose microplex (lipoplex-microsphere) vector enhanced liposome-mediated transfection of cells in culture. When these high-dose microplexes were tested in-vivo, they were better than both microspherical and liposomal delivery modes in terms of transgene expression levels and the tumour-to-normal tissue ratio of gene delivery. Microplexes have been demonstrated to be capable of not only selective delivery of plasmids to solid tumours, but also of increasing transfection in cell culture, a finding that may be used in ex-vivo transfection studies. It is hypothesized that microspheres anchored the combination vector closer to the cultured cells, allowing attached liposomes to gain easier access into cells. In-vivo, microspheres permitted the microplexes to selectively deliver their genetic payload within the tumour tissue, from where the action of cationic liposomes on cellular membranes facilitated increased access of plasmids into the cytosol of target cells.

A model for evaluating selective delivery of plasmid DNA to tumours via the vasculature

A comparative study of plasmid DNA delivery in a newly established rat renal solid tumour model was undertaken. Free plasmid, plasmids bound to microspheres, and plasmids complexed with liposomes were selectively delivered to tumours via arterial catheterisation. Forty-eight hours post delivery, tumour to normal kidney tissue chloramphenicol acetyltransferase expression ratios were as follows: free (1.8:1), microspherical (3.9:1), and liposomal (1.2:1). Microspheres were able to selectively deliver the plasmids to tumours, whereas cationic liposomes distributed the plasmids to both kidney parenchymal and tumour cells. This tumour model has the potential of screening delivery vehicles as well as therapeutic agents for the capacity of selective delivery to tumours via the vasculature.

Enhanced in vivo tumour response from combination of carboplatin and low-dose c-myc antisense oligonucleotides

BACKGROUND

Phosphorothioate oligonucleotides ([S]ODNs) contain a modified phosphate backbone. Antisense [S]ODNs targeted to specific oncogenes have been used to varying success in vivo. Carboplatin is a commonly used chemotherapeutic and is associated with chemoresistance in some human tumours. The potential for combined antisense [S]ODNs and carboplatin chemotherapy has only recently been explored in vivo.

MATERIALS AND METHODS

This study examines the effect of c-myc antisense oligomers delivered in isolation as naked DNA and in combination with carboplatin upon the growth kinetics of an in vivo transplantable adenocarcinoma using rodents.

RESULTS

Tumours treated with a combination of 600 microg of 15-mer c-myc phosphorothioate antisense oligodeoxyribonucleotide and an intravenous administration of carboplatin (3 mg/kg), demonstrated a significant (p<0.05) retardation in tumour growth kinetics relative to a control. Two mismatch antisense controls did not significantly inhibit tumour growth. C-myc protein studies in tumour sections failed to show significant differences in c-myc expression in any of the treated tumours.

CONCLUSION

This study demonstrates that carboplatin affects the relative abundance of c-myc and that combination treatment of carboplatin and c-myc phosphorothioate antisense oligonucleotides in vivo results in synergistic tumour retardation.

Liposomes containing cationic dimethyl dioctadecyl ammonium bromide: formulation, quality control, and lipofection efficiency

This article describes a novel, simple, and relatively inexpensive method to prepare cationic liposomes using an ethanol injection/pressure extrusion method. The study also demonstrated that binding erythrosine dye to cationic liposomes results in a shift of the absorption maximum of the dye from 528 nm to 549 nm at pH 4.25, allowing quantification and visualization of these vesicles. In addition, a relatively simple Ficoll-based gradient centrifugation method for separation of lipoplexes from unbound molecules is presented. Laboratory-formulated dimethyl dioctadecyl ammonium bromide (DDAB) containing liposomes were just as efficient in complexing nucleic acids as commercially available types, and binding increased as the positive to neutral lipid ratio was increased. Transfection efficiency of the DDAB-containing liposomes increased as the ratio of cationic to neutral lipid was increased from 1:1 to 4:1 with either PtdChol or DOPE as the neutral lipid. A concomitant increase in cytotoxicity of CSU-SA1 cancer cells was noted as the ratio of positive to neutral lipid of the liposomes was increased. Nevertheless, our present study showed that the 2:1 liposome is a good choice since it delivers functional plasmids at a comparable rate to commercial liposome formulations, has similar toxicities to the less harmful commercial liposomes, and is at least 1000-fold more economical to prepare inhouse, a major factor to be considered in preclinical and clinical studies with these carriers.

Methylation of CpG sites in exon 2 of the bcl-2 gene occurs in colorectal carcinoma

BACKGROUND

Aberrant bcl-2 expression frequently occurs in colorectal carcinoma. The current study investigated if CpG sites in bcl-2 were methylated in colorectal carcinoma and if methylation correlated with loss of expression of bcl-2 mRNA.

METHODS

Methylation was assessed in 23 matched normal mucosae and colonic carcinomas by Southern blotting with methylation-sensitive enzymes. Expression of bcl-2 mRNA was assessed by Northern blotting.

RESULTS

A SacII site in exon 2 of the bcl-2 gene was methylated in 5 carcinomas, plus an adjacent HpaII sites in 1 tumour. SacII site in the bcl-2 promoter were not methylated. Elevated levels of bcl-2 mRNA were detected in 3 carcinomas, 5 showed decreased expression and 4 were unchanged.

CONCLUSIONS

De novo methylation of CpG sites in exon 2 of the bcl-2 gene occurs during the development of colorectal carcinoma. However, there was no relationship between expression of bc1-2 mRNA and methylation of specific CpG sites.

Tumour dosimetry in human liver following hepatic yttrium-90 microsphere therapy

Radiation dose distributions arising from intrahepatic arterial infusion of 90Y microspheres have been investigated. Tissue samples from normal liver, the tumour periphery and tumour centre were taken from a patient following infusion of 3 GBq of 32 microm diameter resin microspheres labelled with 90Y as treatment for an 80 mm diameter metastatic liver tumour. The measured microsphere distributions in three dimensions were used to calculate radiation dose patterns. Although microspheres concentrated in the tumour periphery, heterogeneous doses were delivered to all tissues. Within the tumour periphery average doses ranged from 200 Gy to 600 Gy with minimum doses between 70 Gy and 190 Gy. The average and minimum doses for the tumour centre sample were 6.8 Gy and 3.7 Gy respectively. In the normal liver sample the average dose was 8.9 Gy with a minimum dose of 5 Gy. Less than 1% of the normal liver tissue volume received more than 30 Gy, the level above which complications have resulted for whole liver exposure using external beam radiotherapy. These calculations suggest that preferential deposition of microspheres in the well-vascularized periphery of large tumours will lead to a high proportion of the tumour volume receiving a therapeutic dose, with most of the normal liver tissue being spared substantial damage.

Analysis of the distribution of intra-arterial microspheres in human liver following hepatic yttrium-90 microsphere therapy

The microscopic distribution of microspheres in human liver following hepatic infusion of 32 microm diameter resin microspheres labelled with 90Y as treatment for an 80 millimetre diameter liver cancer has been investigated. Microspheres were found to deposit inhomogeneously in tissues, preferentially lodging in a region approximately 6 mm wide around the periphery of the tumour. A relative concentration of microspheres of 50 to 70 times that of normal hepatic parenchyma and 65 to 94 times that in the tumour centre was measured in this region. The deposition of spheres in the tumour periphery was not uniform, and cluster analysis showed that the spheres could be classified into clusters. The number of microspheres in a cluster was skewed towards low numbers and cluster sizes varied from 20 to 1500 microm. The observed deposition patterns indicate that the vascular tumour periphery will receive much greater radiation doses from radioactive microspheres than both normal tissue and the avascular tumour centre.

A microsphere-liposome (microplex) vector for targeted gene therapy of cancer. II. In vivo biodistribution study in a solid tumor model

Cationic liposomes are commonly used for transfection of plasmids into mammalian cells, while microspheres have been traditionally used for selective delivery of anticancer agents into tumor vasculature. We have developed a novel vector, comprised of cationic liposomes electrostatically bound to ion-exchange microspheres (termed 'microplex') for targeted gene therapy of solid tumors. The delivery modes tested in a rat solid tumor model were free plasmids, plasmids bound to microspheres, to liposomes, or to the combination vector. The greatest amount of chloramphenicol acetyltransferase (CAT) reporter gene expression in tumors was achieved using the microplex vector; 3.4-fold compared with free, and 1.8-fold compared with both microspherical and liposomal deliveries (p < 0.01). Tumor-to-normal kidney tissue CAT expression ratios were as follows: free 1.9:1; microspherical 3.7:1; liposomal 1.4:1 and microplexical 2.7:1. Expression between the two types of tissues was significantly different (p < 0.01) for all delivery modes. Microspheres targeted the plasmids to the tumors, while the action of cationic liposomes on cellular membranes allowed more plasmids to breach the cell membrane. This study has proven that the novel microplex vector is capable of selective delivery of genes to tumors and has the potential to target genes in clinical trials.

Lipoplexes and tumours. A review

The need for genotherapy to refocus its attention on to laboratory evaluation of better methods rather than proceeding to the clinic with semi-apt tools for genetic transfer has been highlighted in clinical study reports documented to date. Quintessential for tumour genotherapy is the ability to target abnormal cells, hence reducing exposure of normal cells to genetic material whilst maximizing gene dosage to tumour cells. This becomes increasingly important as genotherapy establishes itself in the clinic alongside the older modes of treatment. This review has discussed the applicability of lipoplexes for genotherapy of solid tumours. Lipoplexes have been used extensively for gene transfer into cells, such as cancerous cells, deficient for a certain gene product. While cationic liposomes have many advantages over other forms of delivery mechanisms, several problems hinder their use in-vivo. A closer examination of the physical limitations of current lipoplex preparations, the development and testing of novel formulations, combined with more attention to the cellular processes of cell membrane breaching and nuclear entry, may enhance gene delivery. Essential for tumour genotherapy is the ability to target these lipoplexes into tumour sites whilst reducing gene dosage to other normal tissues. Development of a better lipofection agent may indeed require a collaboration of the fields of physiology, cell biology, molecular biology, biochemistry, chemistry and membrane physics.

A comparison of two computer-based face identification systems with human perceptions of faces

The performance of two different computer systems for representing faces was compared with human ratings of similarity and distinctiveness, and human memory performance, on a specific set of face images. The systems compared were a graph-matching system (Lades M, Vorbrüggen JC, Buhmann J, Lage J, von der Malsburg C, Würtz RP, Konen W. IEEE., Trans Comput 1993;42:300-311.) and coding based on principal components analysis (PCA) of image pixels (Turk M, Pentland A. J Cognitive Neurosci 1991;3:71-86.). Replicating other work, the PCA-based system produced very much better performance at recognising faces, and higher correlations with human performance with the same images, when the images were initially standardised using a morphing procedure and separate analysis of 'shape' and 'shape-free' components then combined. Both the graph-matching and (shape + shape-free) PCA systems were equally able to recognise faces shown with changed expressions, both provided reasonable correlations with human ratings and memory data, and there were also correlations between the facial similarities recorded by each of the computer models. However, comparisons with human similarity ratings of faces with and without the hair visible, and prediction of memory performance with and without alteration in face expressions, suggested that the graph-matching system was better at capturing aspects of the appearance of the face, while the PCA-based system seemed better at capturing aspects of the appearance of specific images of faces.

University performance, gender and the rural health workforce: an analysis of nursing students

The relationship between student gender and performance was examined in first year students enrolled in the Bachelor of Nursing course at Charles Sturt University from 1991 to 1995. A greater proportion of female students achieved passing grades in subjects studied when compared to male students, irrespective of the subject discipline area. Furthermore, a significantly greater proportion of female than male students passed nursing subjects; however, no statistically significant differences in performance were detected in the proportion of male or female students in either science or humanities subjects.

Enhanced anticancer therapy mediated by specialized liposomes

It has been a central aim of experimental and clinical therapeutics to deliver therapeutic agents as close as possible to, or if possible within, a diseased cell. Such targeting achieves two major aims of drug delivery, the maximum dose of therapeutic agent to the diseased cell and avoidance of uptake by and, usually, accompanying side-effects to normal, healthy cells. Conventional liposomes, originally used for studies in membrane biophysics and biochemistry, have been used in therapy for the past two decades. However, when applied to deliver drugs into cells, conventional liposomes proved inefficient and so novel unconventional or specialized liposomes are constantly being prepared to enhance cell-specific delivery in-vivo. One possible way of achieving better targeting is combination of the positive attributes of more than one specialized type of liposome into one vesicle. Although a limited number of studies has examined the combined effect of such dual-specialty liposomes, more studies are warranted using appropriate models. Liposomes are composed of one, a few, or many concentric bilayer membranes which alternate with aqueous spaces. The drugs are encapsulated within the aqueous internal volume if they are hydrophilic or in the lipid bilayers if they are hydrophobic (Kim 1993). Liposomes range in size from 25 nm to more than 20 microns (Sugarman & Perez-Soler 1992). Depending on their solubility and method of formulation antimicrobial, cytotoxic and other conventional drugs, hormones, antigens, enzymes, genetic material, viruses and bacteria can be incorporated in either the aqueous or hydrophobic phase. This review discusses the types and characteristics of non-conventional liposomes used in various modes of cancer therapy, mainly chemotherapy and gene therapy. It concludes with suggestions on improving these novel liposomal to effect better targeting to cancer cells.

The efficacy of doxorubicin microspheres for hepatic micrometastases in a rat tumour model

The use of sustained-release microspheres is of potential benefit as an adjuvant treatment for patients with occult hepatic micrometastases. This study investigates the response of a model of implantable adenocarcinoma micrometastases in the livers of DA rats following the intraportal injection of doxorubicin-incorporated ion-exchange microspheres compared to free drug bolus administration. A point-counting technique was used to determine the percentage of liver consisting of tumour 13 days after treatment. This was used as an indicator of tumour response, as was the derived tumour mass. There was a significantly higher tumour response in animals treated with the microspheres compared to animals treated with free drug delivered at the same concentration. This effect, however, was shown to decrease with a delay in the time of treatment. The tumour response of the sustained-release microspheres was achieved in the absence of any detectable local or systemic toxicity. This study demonstrates the potential of sustained-release microspheres in the treatment of patients with hepatic micrometastases.

The basis for somatic gene therapy of cancer

A decade of advances in understanding of the molecular basis of sporadic and familial cancers has combined with developments in mammalian gene transfer technology to stimulate intensive research into the potential applications of somatic gene therapy for cancer. Somatic gene immunotherapy is already in progress to stimulate and direct the natural targeting capabilities of the immune system against the threat of disseminated residual disease. The association of a plethora of mutated tumor suppressor genes (p53, p16 BRCA1, BRCA2) with diverse cancers has also highlighted the potential of somatic gene therapy with wild-type versions of suppressor genes as an anti-cancer therapeutic modality either in its own right or in synergistic association with traditional anti-cancer therapies. The methodologies for gene transfer technology range from direct intravenous injection of naked modified DNAs to intravenous injection of liposome-encapsulated DNAs or microsphere-bound DNAs. Recombinant retroviral and adenoviral vectors have natural transfection capabilities and display tropism for particular tissues that are of selective advantage against particular cancers. Liposomes display very high efficiencies of gene transfer with the advantages of successful transfer to a wide range of tissue types but their widespread systemic distribution offers problems in relation to selective targeting of tumor cells. The challenges to current gene transfer processes are much the same as that of other anti-cancer therapies: achieving selective targeting of cancer cells whilst optimizing dosages and minimizing the risk of collateral damage to healthy tissues.

Tumour cells surviving in vivo cisplatin chemotherapy display elevated c-myc expression

The c-myc oncogene has been extensively implicated in cell proliferation, cell differentiation and programmed cell death. Aberrant expression of the c-myc gene product has been observed in a range of tumours and has also been implicated in cisplatin (cis-dichlorodiammineplatinum)-mediated chemoresistance. A solid transplantable tumour model in syngeneic DA rats was subjected to treatment with cisplatin to determine the impact of such therapy on endogenous c-myc gene expression. Serially transplanted tumours were intravenously treated with a single cisplatin dose (1 mg/kg) and c-myc expression analysed 2 and 7 days after treatment. The surviving tumour cells display a significant 2-fold elevation in c-myc expression at 48 h and 7 days after treatment. Primary cell cultures have been derived from untreated in vivo tumours of the same model and subjected to treatment with a c-myc phosphorothioate antisense oligomer. Administration of 5 microM c-myc antisense oligomer directed at the initiation codon and first four codons of c-myc mRNA results in total inhibition of c-myc expression and coincident suspension of cell growth for a period of 4 days in culture. Antisense therapies directed at the c-myc gene may well prove an effective tool for treating tumours in conjunction with cisplatin as these findings show that tumour cells surviving cisplatin chemotherapy display elevated c-myc expression.

Adjuvant internal radiation therapy in a model of colorectal cancer-derived hepatic metastases

Selective internal radiation therapy (SIR therapy) is a technique whereby metastatic liver cancer is irradiated by embolising microspheres containing the radionuclide yttrium-90 into the hepatic arterial circulation. To date this technique has not been used as an adjuvant therapy, but rather to treat established metastases in the liver. This study evaluated the use of two intrahepatic radiation doses delivered on radioactive microspheres for the treatment of small, growing micrometastases. Three groups of five rats were each inoculated with tumour spheroids into the portal vein. The resultant liver micrometastases were treated with either 10 or 20 MBq of yttrium-90 microspheres or a sham dose of non-radioactive microspheres injected into the portal vein 2 days following tumour inoculation. The livers of each animal were examined for the presence of metastases after a further 21 days and liver function tests were performed. At the time of sacrifice there was no obvious normal liver damage in any of the rats treated with microspheres. The livers of the sham-treated animals contained extensive signs of tumour deposition. A mean of 34 tumours were taken from the livers of each of the sham-treated animals, whereas only a single tumour was found in one animal treated with 10 MBq of yttrium and eight small tumours from two animals treated with 20 MBq. Liver function tests demonstrated a significant short-term increase in alkaline phosphatase levels in the radiation-treated animals compared with shams, but there were no other indications of any effects on liver function. These results indicate a potential role for SIR therapy in an adjuvant setting with colorectal cancer.

A comparative study of the anticancer efficacy of doxorubicin carrying microspheres and liposomes using a rat liver tumour model

Due to low efficacy of chemotherapy in the treatment of liver cancer, several methods of drug targeting have been investigated. Liposomes designed to carry cytotoxic drugs to the liver are currently under clinical evaluation. While experimental evidence shows promise, this method of drug delivery has several disadvantages that include short shelf life and poor drug delivery into tumour tissue. An alternative strategy for targeted drug delivery involving use of ion exchange microspheres may overcome these limitations while still reducing systemic toxicity and maintaining therapeutic efficacy. The purpose of this study was to determine the relative antitumour efficacy of these two drugs carrying systems in the treatment of liver cancer. Compared to controls, DOX treatment with free drug, liposomes or microspheres significantly reduced tumour growth by 56% (P < 0.001), 51% (P < 0.01) and 79% (P < 0.001) respectively. Furthermore, the DOX-microsphere treatment was significantly better than either of the other DOX treatments (53%, P < 0.05) or the sham-microsphere treated group (64%, P < 0.05). Thus, drug microspheres can increase the anti-tumour efficacy compared to either free or liposomal drug while simultaneously reducing systemic toxicity.

In vitro and in vivo responses of doxorubicin ion exchange microspheres to hyperthermia

The utility of microspheres as targeted drug delivery agents is addressed with reference to using heat during formulation and to administration in combination with hyperthermia. It was demonstrated that rate of loading of the drug doxorubicin onto resin microspheres is enhanced under conditions of elevated temperature but this was shown to increase the incidence of microsphere aggregation. Total amount of drug loaded was related to time rather than temperature such that low temperature loading for up to 24 h produced optimum quality injectates. However, release of doxorubicin from microspheres was significantly increased during elevations of temperature to 43 degrees C. Thus, during hyperthermia doxorubicin release can be increased to provide periods of high drug availability targeted to tumour tissue for concomitant thermochemotherapy with microspheres. The therapeutic benefit derived from this combined therapy was assessed in 20 rabbits with VX2 carcinoma implanted in the liver. Hyperthermia was delivered by 2450 MHz microwave applicator to the exteriorized liver at 43 degrees C for 30 min, while chemotherapy was administered by intratumoural injection of doxorubicin microspheres (2.3 mg) into each tumour. Both hyperthermia and chemotherapy alone significantly reduced the size of tumours 10 days following treatment (p less than 0.01). However, in animals treated with both modalities, the size of tumours was significantly less than either treatment alone (p less than 0.05). These results provide a strong rationale for combining hyperthermia with targeted chemotherapy using microspheres.

Dose response and toxicity of doxorubicin microspheres in a rat tumor model

The therapeutic response and toxic effects of chemotherapy using several doses of doxorubicin in conventional solution form or bound to an ion-exchange resin were compared in a rat tumor model, to assess the relationship of drug dose to therapeutic efficacy and associated toxicity. Single bolus injections of 3.0, 4.5, 6.0, 7.5 and 9.0 mg/kg were administered via the abdominal aorta to rats bearing hindlimb tumors. Tumor size was measured serially and the growth rates of treated groups were compared with a control growth curve. In addition, the effect of empty microspheres on tumor growth rate was assessed. The levels of circulating white blood cells were measured and compared to control levels to provide an indication of the severity of bone marrow toxicity experienced by each form of treatment. Finally, any difference in the distribution of doxorubicin to tumor, hindlimb and cardiac tissue following administration of doxorubicin as free drug or on microspheres was ascertained. Empty ion-exchange resin exerted a small although significant detrimental effect on tumor growth which may be explained by the embolization of microspheres in the precapillary blood vessels of the tumor resulting in a transient delay in tumor growth rate. The lowest dose of doxorubicin produced a significantly better therapeutic response when administered in the free drug form, but higher doses elicited an equivalent delay in tumor growth for both drug microsphere and free drug groups in a dose-dependent manner, with the maximum anti-tumor response occurring at the highest dose. Treatment with free doxorubicin at high doses resulted in significant reductions of circulating white blood cells suggesting the occurrence of bone marrow toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Regression of liver metastases following treatment with yttrium-90 microspheres

Selective internal radiation (SIR) therapy is a technique developed by our group for concentration of Yttrium-90 microspheres into liver metastases. The technique involves laparotomy, insertion of the catheter into the hepatic artery, redistribution of liver blood flow with vaso-active agents and incremental embolization of Yttrium-90 containing microspheres (SIR spheres) into the liver. Twenty-nine patients with non-resectable liver metastases from primary adenocarcinoma of the large bowel were treated by this technique and followed for a minimum of three months to assess evidence of tumour regression. Response to treatment was measured by serial estimations of carcino-embryonic antigen (CEA) and tumour volumes measured from serial computerized tomography (CT) scanning of the liver. There was a fall in the serum CEA level in all 26 patients in whom the serial estimations of CEA were performed following SIR therapy. The overall mean fall in CEA was 70% of pre-treatment levels with 88% of patients (23 of 26) experiencing more than a 50% fall in pre-treatment CEA levels. In 18 of 22 evaluable patients CT measured tumour volumes decreased following SIR therapy. In 48% of patients (10 of 22 patients) the decrease in tumour volume was more than 50%. SIR therapy results in a high rate of tumour regression in patients with liver metastases secondary to large bowel cancer.