Genome-wide DNA methylation analysis identifies promoter hypermethylation in canine malignant melanoma

Canine malignant melanoma is a common cancer with a high mortality rate. Although previous studies have evaluated various aspects of this tumour, the exact mechanism of tumourigenesis remains unknown. Epigenetic mechanisms, such as DNA methylation, have recently gained attention as aetiological factors for neoplasia in humans. This study aimed to analyse genome-wide DNA methylation patterns in canine malignant melanoma based on next-generation sequencing data. A total of 76,213 CpG sites, including 29,482 sites in CpG islands (CGIs), were analysed using next-generation sequencing of methylation-specific signatures, obtained by sequential digestion with enzymes, to compare normal oral mucosal samples from four healthy dogs, four canine melanoma cell lines (3 oral cavity and 1 skin), and five clinical samples of oral canine melanoma. Malignant melanoma showed increased methylation at thousands of normally unmethylated CpG sites in CGIs and decreased methylation at normally methylated CpG sites in non-CGIs. Interestingly, the promoter regions of 81-393 genes were hypermethylated; 23 of these genes were present in all melanoma cell lines and melanoma clinical samples. Among these 23 genes, six genes with "sequence-specific DNA binding" annotation were significantly enriched, including three Homeobox genes-HMX2, TLX2, and HOXA9-that may be involved in the tumourigenesis of canine malignant melanoma. This study revealed widespread alterations in DNA methylation and a large number of hypermethylated genes in canine malignant melanoma.

Abstract P3-05-03: Identification of epigenetically silenced breast cancer driver genes

Breast cancer is clinically and molecularly complex disease driven by aberrant genetic and epigenetic alterations. Epigenetic alterations in particular DNA methylation changes are one of the most important events involved in breast cancer initiation and progression. Previous reports identified many aberrant DNA methylation signatures associated with molecular subtypes of breast cancer and over 100 candidate genes with promoter hypermethylation in breast cancer. However, it remains elusive which of these genes with promoter hypermethylation play “driver” role in tumorigenesis. In previous studies, the average gain of DNA methylation across all cancer samples compared to the average DNA methylation in normal samples has been the criterion to select for potential targets. However, known tumor suppressor driver genes regulated by methylation are relatively infrequently altered in target cancers. Therefore, we propose the paradoxical hypothesis that identifying hypermethylated cancer drivers require focusing on infrequent rather than frequent events. Hence, to identify these potential driver genes, we developed an algorithm with two unique properties. First, unlike previous studies we focused on targets that gained DNA methylation relatively infrequently (10-40%) and that lost expression in breast cancer. Second, using this algorithm, we distinguished cancer dependent gain of DNA methylation from age-dependent gain of methylation. To discern age dependent and independent DNA methylation changes, we generated DNA methylation sequencing data on 29 normal purified breast epithelium (age range 33-82 years old). Furthermore, to study the biological effects of the overexpression or downregulation of these genes, we generated DNA methylation sequencing data on 6 breast cancer cell lines. We also used DNA methylation and RNA expression datasets (675 cancer, 100 normal) available through the TCGA. Using our algorithm, we identified 53 genes with age independent promoter hypermethylation and loss of expression in TCGA tumor samples. To begin testing the biological effects of these driver genes, we performed canonical pathway enrichment analyses using Ingenuity Pathway Analysis software. We also investigated the mutational status of these genes and their molecular subtype enrichment. Based on these analyses, we picked 12 genes (C10orf125, RUNX3, YOD1, FXYD5, SMOC1, SLC16A5, RNLS, DKK1, PNPLA3, FZD10, RND2, and PLCB1) for further study. We stably overexpressed these potential driver genes in different breast cancer cell lines. Twelve genes out of the 12 tested, slowed cell proliferation and 9 decreased anchorage independent growth. We further validated these driver genes by knocking them out in normal human mammary epithelial cells using CRISPR/Cas9 tool. The loss of these genes, increased cell proliferation rate in normal human mammary epithelial cells compared to the control cells. In conclusion, based on our preliminary data, using bioinformatics tools as well as functional assays, we identified epigenetically altered breast cancer driver genes. Identifying and deciphering true epigenetic cancer drivers could potentially lead to the development of therapeutic drugs targeting these genes and/or targeting pathway dependence.

Citation Format: Panjarian S, Madzo J, Slater C, Jelinek J, Chen X, Issa J-P. Identification of epigenetically silenced breast cancer driver genes [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-05-03.

Dynamic changes in DNA methylation patterns in canine lymphoma cell lines demonstrated by genome-wide quantitative DNA methylation analysis

DNA methylation is the conversion of cytosine to 5-methylcytosine, leading to changes in the interactions between DNA and proteins. Methylation of cytosine-guanine (CpG) islands (CGIs) is associated with gene expression silencing of the involved promoter. Although studies focussing on global changes or a few single loci in DNA methylation have been performed in dogs with certain diseases, genome-wide analysis of DNA methylation is required to prospectively identify specific regions with DNA methylation change. The hypothesis of this study was that next-generation sequencing with methylation-specific signatures created by sequential digestion of genomic DNA with SmaI and XmaI enzymes can provide quantitative information on methylation levels. Using blood from healthy dogs and cells obtained from canine lymphoma cell lines, approximately 100,000CpG sites across the dog genome were analysed with the novel method established in this study. CpG sites in CGIs broadly were shown to be either methylated or unmethylated in normal blood, while CpG sites not within CpG islands (NCGIs) were largely methylated. Thousands of CpG sites in lymphoma cell lines were found to gain methylation at normally unmethylated CGI sites and lose methylation at normally methylated NCGI sites. These hypermethylated CpG sites are located at promoter regions of hundreds of genes, such as TWIST2 and TLX3. In addition, genes annotated with 'Homeobox' and 'DNA-binding' characteristics have hypermethylated CpG sites in their promoter CGIs. Genome-wide quantitative DNA methylation analysis is a sensitive method that is likely to be suitable for studies of DNA methylation changes in cancer, as well as other common diseases in dogs.

A phase I study of decitabine with pegylated interferon α-2b in advanced melanoma: impact on DNA methylation and lymphocyte populations

BACKGROUND

Melanoma cell lines treated with decitabine show upregulation of cancer antigens, and interferon-α upregulates MHC Class I antigens in cancer cells, leading to enhanced T-cell recognition and T-cell mediated tumor apoptosis. We evaluated the synergy between the hypomethylating effects of decitabine and the immunomodulatory effects of interferon in a combination regimen administered to advanced melanoma patients in a phase 1 trial.

METHODS

Patients with one prior systemic therapy were eligible. Using a modified 3 + 3 design, patients received escalating doses of decitabine and pegylated interferon α-2b (PEG-IFN) during every 28-day treatment cycle. Global DNA methylation was measured on days 1 and 5 of cycles 1 and 3. Cytokine profiling and quantification of T-cell subpopulations by FACS were performed at baseline and cycle 3.

RESULTS

Seventeen patients were assigned to one of four dose levels. Decitabine 15 mg/m2/d + PEG-IFN 3 μg/kg was the maximum tolerated dose (MTD). Grade 3/4 cytopenias were seen across all dose levels: anemia (1), neutropenia (7), and thrombocytopenia (2). One patient remained progression-free for 37 weeks. The other 16 patients progressed at or before 12 weeks. Median overall survival was 39 weeks. Hypomethylation was seen at all dose levels. Due to treatment-induced lymphocytopenia, absolute changes in T-cell populations post-treatment were too small to be meaningfully interpreted.

CONCLUSIONS

The response to this combination regimen was characterized by significant myelosuppression, particularly neutropenia. Although disappointing efficacy and slow accrual led to early closure of the trial, hypomethylation showed pharmacodynamic evidence of a therapeutic effect of decitabine at all dose levels.

Tolerance and safety evaluation in a large cohort of healthy infants fed an innovative prebiotic formula: a randomized controlled trial

Background

the addition of oligosaccharides to infant formula has been shown to mimic some of the beneficial effects of human milk. The aim of the study was to assess the tolerance and safety of a formula containing an innovative mixture of oligosaccharides in early infancy.

Methodology/Principal Findings

this study was performed as a multi-center, randomized, double-blind, placebo-controlled trial including healthy term infants. Infants were recruited before the age of 8 weeks, either having started with formula feeding or being fully breast-fed (breastfeeding group). Formula-fed infants were randomized to feeding with a regular formula containing a mixture of neutral oligosaccharides and pectin-derived acidic oligosaccharides (prebiotic formula group) or regular formula without oligosaccharides (control formula group). Growth, tolerance and adverse events were assessed at 8, 16, 24 and 52 weeks of age. The prebiotic and control groups showed similar mean weight, length and head circumference, skin fold thicknesses, arm circumference gains and stool frequency at each study point. As far as the anthropometric parameters are concerned, the prebiotic group and the control group did not attain the values shown by the breastfeeding group at any study point. The skin fold thicknesses assessed in the breastfeeding group at 8 weeks were strikingly larger than those in formula fed infants, whereas at 52 weeks were strikingly smaller. The stool consistency in the prebiotic group was softer than in the control group at 8, 16 and 24 weeks (p<0.001) and closer to that of the breastfeeding group. There was no difference in the incidence of adverse events between the two formula groups.

Conclusions

our findings demonstrate the tolerability and the long term safety of a formula containing an innovative mixture of oligosaccharides in a large cohort of healthy infants.

Trial Registration:

drks-neu.uniklinik-freiburg.de DRKS 00000201

A specific prebiotic mixture added to starting infant formula has long-lasting bifidogenic effects

There is some evidence that early colonization of the intestine affects the composition of the intestinal microbiota after weaning. In the present study, the effect of prebiotics administered from the first day of life on fecal counts of bifidobacteria and lactobacilli were studied during and after the administration of the prebiotics. In this double-blind, randomized, placebo-controlled, explorative study, 20 newborns of hepatitis C virus-infected mothers who decided not to breast feed due to their concerns regarding their plasma viral load were randomly assigned to either a formula with 8 g/L of a specific prebiotic mixture (short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides, ratio 9:1) or a formula containing the same amount of maltodextrin (placebo). Clinical examination including anthropometric measurements, microbiological analysis of fecal samples, and blood leukocyte population analysis were performed at birth and 3, 6, and 12 mo age. At the age of 12 mo, hepatitis B vaccine-specific IgG serum titers (Hepatitis B virus surface antibodies) were also measured. Prebiotic supplementation resulted in more fecal bifidobacteria (P < 0.0001) and lactobacilli (P = 0.0044) compared with the placebo group. These differences between the groups were maintained during the second half of the first year without any prebiotic supplementation. There was no influence of the different diets on anthropometric data or the measured immunological variables. The data from this small explorative study indicate that early colonization of the intestine might have long-lasting effects on the composition of the intestinal microbiota.

A specific prebiotic mixture added to starting infant formula has long-lasting bifidogenic effects

There is some evidence that early colonization of the intestine affects the composition of the intestinal microbiota after weaning. In the present study, the effect of prebiotics administered from the first day of life on fecal counts of bifidobacteria and lactobacilli were studied during and after the administration of the prebiotics. In this double-blind, randomized, placebo-controlled, explorative study, 20 newborns of hepatitis C virus-infected mothers who decided not to breast feed due to their concerns regarding their plasma viral load were randomly assigned to either a formula with 8 g/L of a specific prebiotic mixture (short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides, ratio 9:1) or a formula containing the same amount of maltodextrin (placebo). Clinical examination including anthropometric measurements, microbiological analysis of fecal samples, and blood leukocyte population analysis were performed at birth and 3, 6, and 12 mo age. At the age of 12 mo, hepatitis B vaccine-specific IgG serum titers (Hepatitis B virus surface antibodies) were also measured. Prebiotic supplementation resulted in more fecal bifidobacteria (P < 0.0001) and lactobacilli (P = 0.0044) compared with the placebo group. These differences between the groups were maintained during the second half of the first year without any prebiotic supplementation. There was no influence of the different diets on anthropometric data or the measured immunological variables. The data from this small explorative study indicate that early colonization of the intestine might have long-lasting effects on the composition of the intestinal microbiota.

Progesterone Receptor (PR) Promoter Methylation – Role as a Predictive and Prognostic Marker in Breast Cancer

Estrogen receptor α expression is a well known and clinically utilized predictor of endocrine treatment response. In addition, loss of expression of the progesterone receptor (PR), an estrogen induced gene, has been shown to be associated with resistance to endocrine therapy. PR is known to be epigenetically regulated by DNA methylation, but only a few studies have correlated PR DNA methylation with its expression in breast cancer. Previous studies are contradictory and have been limited by small sample size. There is also evidence that differential expression of the two PR isoforms, PRA and PRB, might contribute to breast tumorigenesis, and altered hormone response. Whether PRA and/or PRB DNA methylation could predict response to endocrine therapy remains an open question. Further, there are no published studies so far testing whether PRA and/or PRB methylation have prognostic significance.Our objective was 1) to determine whether there was an association between PRA and/or PRB methylation levels with total PR expression in breast tumors, and 2) to determine if PRA and/or PRB methylation would have predictive and/or prognostic value. For this study, we utilized tumor DNA from patients with ER-positive breast tumors which were treated with adjuvant tamoxifen after surgery (n=500), and from patients treated with surgery only (n=500). PR expression was determined by ligand binding assay, and PRA and PRB promoter methylation was measured by bisulfite pyrosequencing.Both PRA and PRB methylation were significantly (p&lt;0.0001) associated with PR expression, in an inverse relationship. Low PR expression was significantly (p=0.02) associated with worse overall survival (OS), and there was a trend towards shorter disease free survival (DFS) in the tamoxifen treated group. There was no association between PR expression and survival in the untreated group. PRA methylation was significantly (p&lt;0.0001) associated with PRB methylation. Intriguingly, increased PRA methylation was significantly associated with shorter DFS (p=0.047) and OS (p=0.0067) in tamoxifen treated patients, and with shorter OS (p=0.008) in the untreated patients. In contrast, there was no significant association between PRB methylation and survival in either tamoxifen treated or untreated patients.Our results show that PR expression is significantly associated with PR methylation. The data suggest that PRA methylation is a predictive marker for tamoxifen response and also a prognostic marker for breast cancer progression. This is the largest study so far to elucidate the association of PRA and PRB methylation with PR status, response to tamoxifen, and tumor prognosis, and we believe that it provides useful insights into the role of PR methylation in breast tumorigenesis.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2002.

Decitabine effect on human tumor expression of various transporters

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Background: We reported that immunohistochemistry (IHC) expression of the platinum/copper transporter CTR1 in human tumors correlated inversely with DNA methylation and was increased by the DNA demethylating agent decitabine (D. Stewart et al, Proc ASCO 2008). Decitabine also increased expression of folate transporters in platinum-resistant cell lines that have decreased expression of folate transporters and of small GTPases such as RHOA that regulate endocytosis (D Shen et al. Br J Cancer 2004). Methods: Tumors were biopsied pre decitabine and on cycle 1 day 12 in 31 patients with refractory malignancies in a phase I study of decitabine given days 1–5 ± 8–12 each cycle. We used IHC to assess the folate carriers FOLR1 and RFC1, the glucose transporter GLUT4 and the endocytosis regulating small GTPase RHOA. Scores of 0–300 were calculated by multiplying staining intensity (0–3) by % cells staining. LINE assays were used to assess % global DNA methylation. Results: DNA methylation did not correlate with FOLR1, RFC1 and GLUT4 scores but did correlate inversely with RHOA (r= -0.58, p=0.006). Median tumor IHC scores post vs pre decitabine were 80 vs 80 (range, 0–270 vs 0–210, p=0.89) for FOLR1, 90 vs 90 (range, 15–300 vs 0–300, p=0.17) for RFC1, 0 vs 0 (range 0- 140 vs 0–70, p=0.61) for GLUT4, and 77.5 vs 50 (range, 0–210 vs 0–210, p=0.03) for RHOA. If only tumors with pre decitabine scores <150 were included, post vs pre RFC1 differences were significant (95 vs 80, p=0.004). Outcomes were similar whether or not 4 melanoma patients (in whom melanin pigment decreased the reliability of IHC scoring) were included. Conclusions: As previously noted with the copper/platinum transporter CTR1, treatment with the DNA demethylating agent decitabine was associated with a significant increase in tumor expression of the endocytosis regulator RHOA in resistant human tumors. Expression of the folate transporter RFC1 was also increased if only patients with levels that were initially low were included. This suggests that decitabine should be tested for its ability to increase uptake of chemotherapy in resistant tumors. Promoter methylation for these transporters has not yet been assessed. Supported in part by NIH grant UO1 CA062461–10 & R21 CA112895–01A1.

No significant financial relationships to disclose.

A mixture of prebiotic oligosaccharides reduces the incidence of atopic dermatitis during the first six months of age

BACKGROUND

Oligosaccharides may alter postnatal immune development by influencing the constitution of gastrointestinal bacterial flora.

AIMS

To investigate the effect of a prebiotic mixture of galacto- and long chain fructo-oligosaccharides on the incidence of atopic dermatitis (AD) during the first six months of life in formula fed infants at high risk of atopy.

METHODS

Prospective, double-blind, randomised, placebo controlled trial; 259 infants at risk for atopy were enrolled. A total of 102 infants in the prebiotic group and 104 infants in the placebo group completed the study. If bottle feeding was started, the infant was randomly assigned to one of two hydrolysed protein formula groups (0.8 g/100 ml prebiotics or maltodextrine as placebo). All infants were examined for clinical evidence of atopic dermatitis. In a subgroup of 98 infants, faecal flora was analysed.

RESULTS

Ten infants (9.8%; 95 CI 5.4-17.1%) in the intervention group and 24 infants (23.1%; 95 CI 16.0-32.1%) in the control group developed AD. The severity of the dermatitis was not affected by diet. Prebiotic supplements were associated with a significantly higher number of faecal bifidobacteria compared with controls but there was no significant difference in lactobacilli counts.

CONCLUSION

Results show for the first time a beneficial effect of prebiotics on the development of atopic dermatitis in a high risk population of infants. Although the mechanism of this effect requires further investigation, it appears likely that oligosaccharides modulate postnatal immune development by altering bowel flora and have a potential role in primary allergy prevention during infancy.

Dietary prebiotic oligosaccharides are detectable in the faeces of formula-fed infants

Human milk oligosaccharides are not digested during intestinal passage and can be detected in stools. In this study it was investigated whether a prebiotic mixture of low-molecular-weight galacto-oligosaccharides (GOS) and high-molecular-weight fructo-oligosaccharides (FOS) can be detected in stool samples of formula-fed infants. The test formula was supplemented with 0.8 g/dl oligosaccharides (GOS+FOS). In the control formula, maltodextrins were used as placebo. Fecal flora was assessed at the beginning (day 1) and at the end of a 28-d feeding period (day 2). At day 2 the content of galacto- and fructo-oligosaccharides in the stool samples were measured. On study day 1, the number of bifidobacteria was not different among the groups (supplemented group: 7.7 (6.2) CFU/g; placebo group: 8.0 (6.0) CFU/g). At the end of the 28-d feeding period, the number of bifidobacteria was significantly higher in the group fed the supplemented formula when compared to placebo (supplemented group: 9.8 (0.7) CFU/g stool; placebo group: 7.1 (4.7) CFU/g stool; p<0.001). In all infants fed the supplemented formula, GOS and FOS could be identified in the stool samples. That was not the case in infants fed the non-supplemented formula.

CONCLUSION

The present data confirm the bifidogenicity of oligosaccharides and indicate that dietary galacto-oligosaccharides and long chain fructo-oligosaccharides remain during the whole passage in the lumen of the gastrointestinal tract, similarly to human milk oligosaccharides.

Increase of faecal bifidobacteria due to dietary oligosaccharides induces a reduction of clinically relevant pathogen germs in the faeces of formula-fed preterm infants

In a previous study on formula-fed preterm infants, we were able to demonstrate that dietary oligosaccharides (a mixture of 90% galacto-oligosaccharides and 10% fructo-oligosaccharides in a concentration of 1 g/dl) stimulate the growth of faecal bifidobacteria. In the present explorative analysis of this study, we focus on the effect of the dominance of bifidobacteria on the presence of clinically relevant pathogens (Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Pseudomonas aeruginosa, Enterobacter, Klebsiella, Proteus, Streptococcus group B, Clostridium difficile, Bacillus subtilis and Acinetobacter).

CONCLUSION

The data demonstrate that stimulation of bifidobacteria by prebiotic oligosaccharides reduces the presence of clinically relevant pathogens in the faecal flora, indicating that prebiotic substances might have the capacity to protect against enteral infections.

Prebiotic carbohydrates in human milk and formulas

Human milk oligosaccharides play an important role, as prebiotic soluble fibres, in the postnatal development of the intestinal flora. Infant formulas are virtually free of prebiotic oligosaccharides. As a consequence, formula-fed infants develop an intestinal flora significantly different to the flora of breastfed infants. Due to the complexity of human milk oligosaccharides, it is necessary to use alternative sources of prebiotic ingredients as components of infant formulas. The present review summarizes the data of experimental research and clinical studies with a prebiotic mixture containing 90% short-chain galacto-oligosaccharides and 10% long-chain fructo-oligosacchrides are summarized. The data demonstrate that, with this prebiotic mixture, the growth of bifidobacteria and lactobacilli can be stimulated, the faecal pH can be decreased, and the presence of pathogens can be reduced to levels similar to those of breastfed infants. Thus, prebiotic oligosaccharides such as the studied mixture provide beneficial effects for formula-fed infants.

Prebiotic carbohydrates in human milk and formulas

Human milk oligosaccharides play an important role, as prebiotic soluble fibres, in the postnatal development of the intestinal flora. Infant formulas are virtually free of prebiotic oligosaccharides. As a consequence, formula-fed infants develop an intestinal flora significantly different to the flora of breastfed infants. Due to the complexity of human milk oligosaccharides, it is necessary to use alternative sources of prebiotic ingredients as components of infant formulas. The present review summarizes the data of experimental research and clinical studies with a prebiotic mixture containing 90% short-chain galacto-oligosaccharides and 10% long-chain fructo-oligosacchrides are summarized. The data demonstrate that, with this prebiotic mixture, the growth of bifidobacteria and lactobacilli can be stimulated, the faecal pH can be decreased, and the presence of pathogens can be reduced to levels similar to those of breastfed infants. Thus, prebiotic oligosaccharides such as the studied mixture provide beneficial effects for formula-fed infants.

Dietary prebiotic oligosaccharides are detectable in the faeces of formula-fed infants

Human milk oligosaccharides are not digested during intestinal passage and can be detected in stools. In this study it was investigated whether a prebiotic mixture of low-molecular-weight galacto-oligosaccharides (GOS) and high-molecular-weight fructo-oligosaccharides (FOS) can be detected in stool samples of formula-fed infants. The test formula was supplemented with 0.8 g/dl oligosaccharides (GOS+FOS). In the control formula, maltodextrins were used as placebo. Fecal flora was assessed at the beginning (day 1) and at the end of a 28-d feeding period (day 2). At day 2 the content of galacto- and fructo-oligosaccharides in the stool samples were measured. On study day 1, the number of bifidobacteria was not different among the groups (supplemented group: 7.7 (6.2) CFU/g; placebo group: 8.0 (6.0) CFU/g). At the end of the 28-d feeding period, the number of bifidobacteria was significantly higher in the group fed the supplemented formula when compared to placebo (supplemented group: 9.8 (0.7) CFU/g stool; placebo group: 7.1 (4.7) CFU/g stool; p<0.001). In all infants fed the supplemented formula, GOS and FOS could be identified in the stool samples. That was not the case in infants fed the non-supplemented formula.

CONCLUSION

The present data confirm the bifidogenicity of oligosaccharides and indicate that dietary galacto-oligosaccharides and long chain fructo-oligosaccharides remain during the whole passage in the lumen of the gastrointestinal tract, similarly to human milk oligosaccharides.

Acidic oligosaccharides from pectin hydrolysate as new component for infant formulae: effect on intestinal flora, stool characteristics, and pH

OBJECTIVES

To come even closer to the functional composition of human milk, acidic oligosaccharides (AOS) from pectin were added to well known neutral prebiotics (galacto-oligosaccharides (GOS) and long-chain fructo-oligosaccharides (FOS)). The effect of AOS and GOS/FOS/AOS on intestinal flora, stool characteristics as well as acceptance and tolerance was investigated.

METHODS

Human milk contains 75% to 85% neutral and 15% to 25% acidic oligosaccharides. In this prospective, randomized, double blind study, a mixture of 80% neutral oligosaccharides (from long-chain galacto- and long-chain fructo-oligosaccharides) with 20% acidic oligosaccharides derived from pectin hydrolysis was investigated. Forty-six term infants were fed a standard formula supplemented with either maltodextrin as control (n=15), or with 0.2 g acidic oligosaccharides (n=16), or with the latter plus 0.6 g neutral oligosaccharides (mixture of galacto- and fructo-oligosaccharides; n=15). Fecal flora using plating technique and pH were measured. Stool characteristics and possible side effects (crying, vomiting, and regurgitation) were recorded.

RESULTS

There was no difference in the bifidobacteria counts between the control and the group supplemented with acidic oligosaccharides alone (8.75+/-0.50 vs. 8.58+/-0.94 log colony forming units [CFU]/g stool). In infants fed the combination of acidic and neutral oligosaccharides, bifidobacteria were increased (9.61+/-0.70 log CFU/g stool; P<0.01). The same pattern was observed with lactobacilli. Stool consistency was softest in infants fed the complete oligosaccharide mixture, but also in those fed formula supplemented with acidic oligosaccharides alone, the stool consistency was significantly softer compared with the control group. Fecal pH increased in the controls, remained constant in acidic oligosaccharides alone, and decreased in the complete mixture of oligosaccharides group.

CONCLUSION

There was no difference in growth, crying, vomiting, and regurgitation patterns between the groups. In summary, acidic oligosaccharides from pectin hydrolysate are well tolerated as ingredient in infant formulae but do not affect intestinal microecology.

Prebiotics in infant formulas

BACKGROUND

The intestinal flora of breast-fed infants is an important physiologic factor in the function of the gut and in the development of the immune system. The current research is part of a group of studies performed to answer the question whether a bovine milk formula supplemented with a prebiotic mixture from galactooligosaccharides and fructooligosaccharides can stimulate an intestinal flora similar to that of breast-fed infants.

METHODS

The prebiotic effect of the oligosaccharide mixture was tested in preterm and term infants by measuring fecal flora using plating as well as fluorescent in situ hybridization techniques. The effect of the oligosaccharides on the bacterial metabolism was studied by measuring short-chain fatty acid production in vitro and the short-chain fatty acid pattern in the stools of a group of term infants.

RESULTS

The oligosaccharide mixture increases significantly the number of bifidobacteria and reduces the number of pathogens in term as well as in preterm infants when compared with a group of infants fed an unsupplemented formula. Using a concentration of 0.8 g oligosacchrides/100 mL formula, the amount of bifidobacteria is similar to that typical of breast-fed infants. In vitro, the short-chain fatty acids produced by the mixture of oligosaccharides under study were similar to those produced by the human milk oligosaccharides fraction. In clinical trials the pattern of fecal short-chain fatty acids in infants fed the oligosaccharide mixture was similar to that of breast-fed infants but was significantly different from that of a group of infants fed with an unsupplemented formula. Additionally, the fecal pH was significantly higher in the group fed an unsupplemented formula than in the groups fed either breast milk or a supplemented formula.

CONCLUSION

The data obtained indicate that the prebiotic mixture under study is able to stimulate the development of a microbial flora similar to that of breast-fed infants. Several biota, whose growth is enhanced by this prebiotic mixture, represent important factors in the postnatal development of the immune system. On this evidence it can be suggested that prebiotics may play a role as modulators of the postnatal development of the immune system.

Short term effects of dietary medium-chain fatty acids and n-3 long-chain polyunsaturated fatty acids on the fat metabolism of healthy volunteers

BACKGROUND

The amount and quality of dietary fatty acids can modulate the fat metabolism.

OBJECTIVE

This dietary intervention is based on the different metabolic pathways of long-chain saturated fatty acids (LCFA), which are mostly stored in adipocytic triacylglycerols, medium-chain fatty acids (MCFA) which are preferentially available for hepatic mitochondrial beta-oxidation and n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) suggested to modulate fat oxidation and storage by stimulating the peroxisomal beta-oxidation. Combined dietary MCFA and n-3 LCPUFA without LCFA may synergistically stimulate fatty acid oxidation resulting in blood lipid clearance and LCFA release from adipocytes.

DESIGN

In a short term, parallel, randomized, double-blind trial effects on the fatty acid metabolism of 10 healthy volunteers (Body Mass Index 25-30) of a formula containing 72% MCFA and 22% n-3 LCPUFA without LCFA (intake: 1.500 kcal/day; fat: 55.5% of energy) were measured in comparison to an isoenergetic formula with equal fat amount and LCFA dominated lipid profile.

RESULTS

The plasma triacylglycerol (p < 0.1) and cholesterol (p < 0.05) content decreased in the test group. The n-3/n-6 LCPUFA (> or = C 20) ratio increased (p < 0.0001) after 4 days treatment. The LCFA content was similar in both groups despite missing LCFA in the test formula indicating LCFA release from adipocytes into the plasma. Both groups significantly reduced body weight considerably 4 kg (p < 0.01) and fat mass up to 50% of weight loss (p < 0.05).

CONCLUSION

Combined dietary 72% MCFA and 22% n-3 LCPUFA without LCFA stimulate the fatty acid oxidation and release from adipocytes without affecting any safety parameters measured.

Prebiotic concept for infant nutrition

In the neonatal period, the intestine is colonised in a stepwise process that depends on mode of delivery, environmental factors, bacterial interactions, and the host itself resulting in a colonisation with a complex heterogeneous bacterial flora. Oligosaccharides have been identified as an important prebiotic factor of human milk As long as analogues of human milk oligosaccharides are not available now and in the near future it is aimed to resemble the prebiotic effect of human milk by oligosaccharides from available sources. In the present study in preterm infants, a mixture of 90% galacto-oligosaccharides and 10% fructo-oligosaccharides has been tested. The mixture of GOS/FOS was composed to mimic the molecule size distribution of human milk oligosaccharides. Microbiological analysis of the faces was performed before and 7, 14, and 28 days after start of supplementation and stool characteristics have been recorded. Maltodextrin was used as placebo and infants fed human milk have been used as reference. After a 28 days feeding period, the number of bifidobacteria of the group fed the oligosaccharide supplemented formula was in the upper range of the reference group whereas the numbers of the group fed the formula supplemented with the placebo were in the lower range of the reference group (placebo: 7.9 +/- 0.83 and GOS/FOS mixture: 10,0 +/- 2.05 log 10 CFU/g wet stool; reference (M +/- SD): 7.14-10.7 log 10 CFU/g wet stool). Stool characteristics in the group fed the supplemented formula were close to those found in the human milk fed infants. In summary, supplementation of a preterm formula with a mixture of galacto- and fructo-oligosaccharides has a stimulating effect on the growth of bifidobacteria in the intestine and results in more frequent produced and softer stools. Thus, prebiotic mixtures such like the studied oligosaccharide mixture might help in improving intestinal tolerance to enteral feeding in preterm infants.

Effects of a new mixture of prebiotics on faecal flora and stools in term infants

A double-blind, randomized, controlled study was performed in 90 full term infants to evaluate dose-related bifidogenic effects of a new synergistic mixture of galacto-oligosaccharides (GOS) and fructo-oligosacharides (FOS). The GOS/FOS mixture showed a dose-dependent stimulatory effect on the intestinal growth of bifidobacteria. Also stool consistency and faecal pH were positively affected.

Impact of splice-site mutations of the human MDR1 cDNA on its stability and expression following retroviral gene transfer

The multidrug resistance 1 (MDR1) gene transfer to hematopoietic cells for protection against cytotoxic drugs has received considerable attention in gene therapy. However, ectopic expression of MDR1 from retroviral vectors has been hampered by its genetic instability resulting from cryptic splice sites within the cDNA. We have evaluated the efficiency of retroviral MDR1 vectors with introduced mutations of the MDR1 cryptic splice donor (cSD) located at nucleotide +339 and of the cryptic splice acceptor (cSA) at nucleotide +2319 of the cDNA. Sequence alterations of the cSD reduced the expression of MDR1 P-glycoprotein (P-gp), even when generated as silent mutations. A silent mutation of the cSA reduced the splicing activity shifting the splice acceptor site one base downstream; however, it significantly improved the expression of P-gp. The incidence of wild-type MDR1 pregenome splicing was markedly reduced when vectors were produced in human 293 packaging cells as opposed to murine PG13 and GP+envAm12. We conclude that complete splice correction of MDR1 in retroviral vectors may only be achieved with extensive alterations of the cDNA or neighboring vector sequences and that the splicing is significantly influenced by the choice of the packaging cells.

Dietary threonine reduces plasma phenylalanine levels in patients with hyperphenylalaninemia

BACKGROUND

In order to achieve normal intellectual development, the plasma phe-nylalanine (PHE) levels of patients with hyperphenylalaninemia should not exceed toxic levels. This goal is usually accomplished by employing special diets in which the patient's protein intake is in the form of PHE-free mixtures of amino acids. There is evidence from our own observations in animals and a preliminary observation in patients with hyperphenylalaninemia that supplemental dietary threonine (THR) might decrease plasma PHE concentrations.

METHODS

In this placebo-controlled crossover study, the effect of supplemental oral THR on the plasma amino acid concentrations of 12 patients with hyperphenylalaninemia was investigated. Before starting the first treatment period of this cross-over study, the patients were randomly assigned to one of two groups supplemented either with approximately 50 mg THR/kg per day or with a similar amount of maltodextrin as placebo. After a feeding period of 8 weeks and a wash-out period of 8 weeks, the supplements were crossed over and the study continued for an additional 8 weeks. Blood was obtained at the start and the end of each supplementation period.

RESULTS

Dietary THR supplementation of approximately 50 mg/kg per day resulted in a significant decrease of plasma PHE levels ( P = 0.0234). There was a close positive correlation between plasma and urinary PHE concentrations ( P < 0.001) indicating that the lower plasma PHE levels in the THR supplemented patients were not caused by higher urinary excretion of PHE.

CONCLUSIONS

The data of the present study show that oral THR supplementation has a clear plasma-PHE-reducing effect but they do not allow any conclusion about the mechanisms responsible for the observed effect. Although it seems attractive on the basis of the present data to use THR supplementation in patients with hyperphenylalaninemia, the mechanism of the observed effect should be clarified before introduction of such a treatment in these patients.

Supplementation of a bovine milk formula with an oligosaccharide mixture increases counts of faecal bifidobacteria in preterm infants

BACKGROUND

The establishment of a balanced intestinal microflora which may protect against infection is desirable for the preterm infant.

OBJECTIVE

To investigate the effect of a preterm formula milk supplement consisting of oligosaccharides in similar proportions to human milk on the faecal flora and stool characteristics of preterm infants.

STUDY DESIGN

To resemble the effect of human milk, an oligosaccharide mixture consisting of 90% galacto-oligosaccharides and 10% fructo-oligosaccharides was used to supplement a standard preterm formula at a concentration of 10 g/l. This supplemented formula was studied in 15 preterm infants, and the results were compared with those found in 15 infants fed a formula supplemented with maltodextrin as placebo. A group fed fortified mother's milk was investigated as a reference group (n = 12). On four days during a 28 day feeding period (1, 7, 14, and 28), the faecal flora was investigated, and stool characteristics, growth, and possible side effects were recorded.

RESULTS

During the study period, the number of bifidobacteria in the group fed the oligosaccharide supplemented formula increased to the upper range of bifidobacteria counts in the reference group. The difference between the supplemented and non-supplemented groups was highly significant (p = 0.0008). The stool characteristics were also influenced by the supplement: the stool frequency after 28 days was significantly lower in the control group than in the oligosaccharide supplemented group (p = 0.0079) and the reference group (p < 0.0001). Over the study period, the stool consistency in the control group became harder, but remained fairly stable in the other two groups. There was no effect of the different diets on the incidence of side effects (crying, regurgitation, vomiting) or on weight gain or length gain.

CONCLUSION

Supplementing preterm formula with a mixture of galacto- and fructo-oligosaccharides at a concentration of 10 g/l stimulates the growth of bifidobacteria in the intestine and results in stool characteristics similar to those found in preterm infants fed human milk. Therefore prebiotic mixtures such as the one studied may help to improve intestinal tolerance to enteral feeding in preterm infants.

Dosage-related bifidogenic effects of galacto- and fructooligosaccharides in formula-fed term infants

BACKGROUND

Human milk oligosaccharides have been shown to stimulate selectively the growth of Bifidobacteria and Lactobacilli in the intestine. In this study, the bifidogenic effect of an experimental prebiotic oligosaccharide mixture consisting of low-molecular-weight galactooligosaccharides and high-molecular-weight fructooligosaccharides was analyzed in 90 term infants.

METHODS

Two test formulas were supplemented with either 0.4 g/dL or with 0.8 g/dL oligosaccharides. In the control formula, maltodextrin was used as placebo. At study day 1 and study day 28, the fecal species, colony forming units (cfu) and pH were measured and stool characteristics, growth, and side effects were recorded.

RESULTS

At study day 1, the median number of Bifidobacteria did not differ among the groups (0.4 g/dL group, mean [interquartile range] 8.5 [1.9] cfu/g; 0.8 g/dL group, 7.7 [6.1] cfu/g; and the placebo group, 8.8 [6.1] cfu/g) (figures in square brackets are interquartile range). At the end of the 28-day feeding period, the number of Bifidobacteria was significantly increased for both groups receiving supplemented formulas (the 0.4 g/dL group, 9.3 [4.9] cfu/g; the 0.8 g/dL group, 9.7 [0.8] cfu/g) versus the placebo group (7.2 [4.9] cfu/g, P < 0.001). This effect was dose dependent (0.4 g/dL versus 0.8 g/dL, P < 0.01). The number of Lactobacilli also increased significantly in both groups fed the supplemented formulas (versus placebo, P < 0.001), but there was no statistically significant difference between the group fed formula with 0.4 g/dL oligosaccharides and the group fed formula with 0.8 g/dL oligosaccharides. The dosage of supplement significantly influenced the change in fecal pH (P < 0.05) (placebo, pH 5.5-6.1; 0.4 g/dL formula, pH 5.48-5.44; 0.8 g/dL formula, pH 5.54-5.19). Slight changes in the stool frequency resulted in a significant difference between the placebo group and the group fed the 0.8 g/dL formula at day 28 (P < 0.01). Supplementation had a significant dose-dependent influence on stool consistency (0.8 g/dL versus placebo, P < 0.0001; 0.8 g/dL versus 0.4 g/dL, P < 0.01). Supplementation had no influence on the incidence of side effects (crying, regurgitation, vomiting) or growth.

CONCLUSIONS

These data indicate that supplementation of a term infant's formula with a mixture of galacto- and fructooligosaccharides has a dose-dependent stimulating effect on the growth of Bifidobacteria and Lactobacilli in the intestine and results in softer stool with increasing dosage of supplementation.

TRAIL (Apo2L) suppresses growth of primary human leukemia and myelodysplasia progenitors

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL, APO2L) has been shown to induce apoptosis in a number of tumor cell lines as well as in some primary tumors whereas cells from most normal tissues are highly resistant to TRAIL-induced apoptosis. We have studied the susceptibility of primary malignant and normal bone marrow hematopoietic progenitors to TRAIL-induced apoptosis. Extracellular domain of human TRAIL with N-terminal His(6) tag (His-TRAIL, amino acids 95-281) was produced in E. coli and its apoptosis-inducing ability was compared with the leucine-zipper containing TRAIL, LZ-TRAIL. Both variants of TRAIL had the same apoptosis-inducing ability. Clonogenic progenitor assays showed that His-TRAIL significantly reduced the number of myeloid colonies (CFU-GM) and clusters from patients with acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and myelodysplastic syndromes (MDS). His-TRAIL had no negative effect on the number of CFU-GM colonies and clusters derived from bone marrow cells of AML patients in complete remission, and lymphoma patients without bone marrow involvement, as well as those derived from normal cord blood cells. Moreover, we found that normal human stem cells treated with high doses of His-TRAIL maintain a repopulating potential when transplanted into NOD/SCID mice. To conclude, our data document that TRAIL does not affect normal human hematopoiesis but suppresses the growth of early primary leukemia and myelodysplasia progenitors.

An infant formula free of glycomacropeptide prevents hyperthreoninemia in formula-fed preterm infants

BACKGROUND

Hyperthreoninemia is a well-known phenomenon in infants fed a whey protein-predominant formula. Sweet whey is commonly used for the production of these whey-predominant infant milk formulas. Sweet whey contains not only whey proteins but also the threonine-rich glycomacropeptide (GMP). In the current study, an experimental formula based on acid whey without GMP and a formula based on sweet whey with GMP (threonine content 17.2% higher than in the experimental formula) but otherwise with identical composition were tested with particular respect to threonine metabolism.

METHODS

Fourteen preterm infants appropriate for gestational age were enrolled in this randomized cross-over study. After a feeding period of at least 7 days, the nutrition of each infant was switched to the other formula for the second feeding period. At the end of each feeding period, the concentrations of creatinine and amino acids in the plasma and in the urine were measured.

RESULTS

In the plasma, the threonine concentration was significantly lower in the group fed the experimental GMP-free formula than in the group fed the sweet whey formula (P < 0.001). Renal excretion of all essential amino acids was generally very low and less than 2% of the intake, indicating that the kidneys had no marked homeostatic function with respect to plasma amino acid. The plasma concentrations of the threonine metabolites glycine and serine, and that of urea were not influenced by diet.

CONCLUSION

Feeding a whey protein-predominant bovine milk produced from acid whey protein reduces significantly the hyperthreoninemia commonly found in formula-fed preterm infants. Thus, acid whey formulas should be recommended for feeding preterm infants.

Effect of preterm formula with and without long-chain polyunsaturated fatty acids on the urinary excretion of F2-isoprostanes and 8-epi-prostaglandin F2alpha

BACKGROUND

The objective of this study was to evaluate the effect of conventional and long-chain polyunsaturated fatty acids (LCP)-enriched preterm formula on the endogenous formation of F2-isoprostanes and 8-epi-prostaglandin (PG) F2alpha as possible markers of lipid peroxidation in preterm infants during their first weeks of life.

METHODS

In a prospective, randomized, double-blind study, infants received either formula enriched with LCP (n = 8), standard preterm formula (n = 7), or (expressed) breast milk (n = 8). Urine was sampled at study entry and after the study period of 3 weeks. The formation of F2-isoprostanes and 8-epi-PGF2alpha was evaluated by measuring the urinary excretion by gas chromatography-mass spectrometry.

RESULTS

No differences in the urinary excretion of F2-isoprostanes and 8-epi-PGF2alpha were observed at the end of the study period.

CONCLUSIONS

This result suggests that supplementation of a preterm formula with LCP for a period of 3 weeks does not stimulate lipid peroxidation in preterm infants.

The percutaneous needle biopsy is safe and recommended in the diagnosis of musculoskeletal masses

BACKGROUND

The purpose of this study was to analyze the role of percutaneous core needle biopsy in the diagnosis of musculoskeletal sarcomas.

METHODS

One hundred eighty-five biopsy procedures were performed on 161 musculoskeletal tissue masses suspected of being a sarcoma in 155 patients who underwent subsequent tumor resection. A percutaneous core needle biopsy was performed on all masses either in the clinic or under radiologic guidance. If an adequate diagnosis could not be made on the basis of this biopsy specimen, an open incisional biopsy was performed.

RESULTS

One hundred seventy-three core needle biopsy procedures were performed: 90 without radiologic guidance, 55 computed tomography guided, and 28 fluoroscopically guided. Twelve open incisional biopsies were performed. Eighty-three sarcomas, 67 benign mesenchymal tumors, and 11 metastatic epithelial tumors were identified. Analysis of the data reveals that only 7.4% of the masses required open biopsy. In 88.2% of the masses, a single percutaneous biopsy procedure was adequate, and no additional biopsy was necessary. There was a 1.1% rate of complications; none caused a change in the patient's treatment plan. There was a 1.1% rate of major diagnostic errors, none of which ultimately impacted on the patient's outcome. There were no unnecessary amputations. Percutaneous needle biopsy showed a positive predictive value of 100%, a negative predictive value of 82%, a sensitivity of 81.8%, and a specificity of 100%. The accuracy of a single-needle biopsy procedure to identify benign versus malignant lesions, exact grade, and exact pathology was 92.4%, 88.6%, and 72.7%, respectively.

CONCLUSIONS

The percutaneous needle biopsy was found to be extremely effective and safe for the diagnosis of musculoskeletal masses. This method allowed 88% of patients with suspected sarcomas to undergo a single-needle biopsy procedure before the initiation of definitive treatment. Patients undergoing percutaneous needle biopsy had lower rates of major diagnostic errors and complications than previously described for open biopsy. Open biopsy offered limited additional information when preceded by a needle biopsy, given that these tumors were difficult to identify even after final resection.

Ultrasound-guided fine-needle aspiration and thyroid disease

BACKGROUND

Fine-needle aspiration represents a critical diagnostic test in determining proper management of thyroid disease and the use of ultrasound-guided fine-needle aspiration (USGFNA) has increased over the years.

METHODS

A retrospective chart review of patients undergoing USGFNA. Two hundred fifteen patients underwent 234 procedures with 362 nodules aspirated within a 2 (1/2)-year period.

RESULTS

The mean ages of women and men were 51.9 and 57.8, respectively. The average size of nodules was 2.1 cm. A difficult to assess gland or nodule was the most common indication for USGFNA (33%). The sensitivity was 88.2%, specificity was 80.0%, the PPV was 65.2%, the negative predictive value was 94.1%, and the accuracy was 82.5%. The cancer yield, inadequacy, and complication rates were 44%, 10.5%, and 8.5%, respectively.

CONCLUSIONS

USGFNA aspiration is a safe and effective diagnostic modality in the management of thyroid disease, especially for nodules that are difficult to palpate.

Chromatin remodeling gene SMARCA5 is dysregulated in primitive hematopoietic cells of acute leukemia

We identified a subset of genes involved in chromatin remodeling whose mRNA expression changes in differentiating mouse erythroleukemia (MEL) cells. We furthermore tested their mRNA expression patterns in normal and malignant CD34+ bone marrow cells. SMARCA5, imitation switch gene homologue, was rapidly silenced during in vitro erythroid differentiation of MEL cells whereas it was up-regulated in CD34+ hematopoietic progenitors of acute myeloid leukemia (AML) patients. Moreover, SMARCA5 mRNA levels decreased in AML CD34+ progenitors after the patients achieved complete hematologic remission. We detected high levels of SMARCA5 mRNA in murine bone marrow and spleen and monitored its expression in these hematopoietic tissues during accelerated hematopoiesis following hemolytic anemia induced by phenylhydrazine. SMARCA5 expression levels decreased after the onset of accelerated erythropoiesis. Our data suggest that both in vitro and in vivo induction of differentiation is followed by down-regulation of SMARCA5 expression. In CD34+ AML progenitors over-expression of SMARCA5 may thus dysregulate the genetic program required for normal differentiation.

Ribosomal protein S19 gene mutations in patients with diamond-blackfan anemia and identification of ribosomal protein S19 pseudogenes

Diamond-Blackfan anemia (DBA) is a rare congenital pure red cell hypoplasia characterized by a selective defect of erythropoiesis with a normochromic macrocytic anemia and reticulocytopenia often accompanied by various congenital anomalies. The critical region responsible for the pathogenesis of DBA has been mapped in some patients to chromosome 19q13.2 (P Gustavsson, E Garelli, N Draptchinskaia, et al. Am. J. Hum. Genet. 63:1388-1395, 1998) and the gene encoding ribosomal protein S19 (RPS19) is believed to be the candidate gene. Here we present molecular analysis of the RPS19 gene in DBA patients from the Czech National DBA Registry. We found that the RPS19 gene was mutated in 25% (5/20) of DBA patients (insertion, deletion, and point mutations, but no nonsense or splice site mutations). Point mutations were localized to hot spots defined by Willig (TN Willig, N Draptchinskaia, I Dianzani, et al. Blood 94:4294-4306, 1999). Moreover, we describe two processed RPS19 pseudogenes, which were not expressed. Possible models of the DBA pathogenesis in the view of RPS19 mutations are discussed.

A novel dual function retrovirus expressing multidrug resistance 1 and O6-alkylguanine-DNA-alkyltransferase for engineering resistance of haemopoietic progenitor cells to multiple chemotherapeutic agents

Following transduction with a retrovirus (SF1MIH) expressing both the multidrug resistance 1 (MDR1) and O6-alkylguanine-DNA-alkyltransferase (ATase) proteins, human erythroleukaemic progenitor (K562) cells were isolated which were resistant to killing by the MDR1 substrate, colchicine. In colony-forming survival assays, K562-SF1MIH cells exhibited resistance to colchicine and doxorubicin, as well as to the O6-alkylating agents N-Methyl-N-nitrosourea (MNU) and temozolomide. Furthermore, the resistance to doxorubicin was abolished by preincubation with the MDR1 inhibitor verapamil while resistance to MNU was ablated by the specific ATase inactivator, O6-benzylguanine (O6-beG) confirming that resistance to doxorubicin and MNU was conferred by MDR1 and ATase, respectively. When K562-SF1MIH were exposed to combinations of colchicine and MNU or doxorubicin and temozolomide, simultaneous resistance to these agents was observed. Thus, transduction of K562 with SF1MIH conferred dual resistance to these cells. These data offer the prospect of designing vectors that will confer resistance to entire regimens of chemotherapy rather than just to individual components of such drug cocktails, thereby substantially increasing the efficacy of therapy. Furthermore, the use of such dual expression constructs is likely to be highly informative for the design of effective in vivo selection protocols, an issue likely to make a major impact in a clinical context in gene therapy in the near future.

Postprandial plasma amino acids in preterm infants: influence of the protein source

Preprandial plasma amino acid concentrations have been used extensively as a marker of the nutritional value of dietary proteins in preterm infants. This study investigated the postprandial plasma amino acid profiles of preterm infants fed with different dietary proteins at similar protein intakes during the first weeks of life. In 12 preterm infants, pre- and postprandial plasma amino acid concentrations were measured before the removal of an indwelling central venous catheter placed for parenteral nutrition. All infants received breast milk until the time of study. At the start day of the study, infants were randomized to receive a test meal of 10 ml/kg, either of breast milk fortified with breast milk protein to reach a protein content of 2.0 g/dl or of a bovine milk preterm formula with a protein content of 2.0 g/dl (whey/casein ratio 60/40). Five samples of 100 microl blood were obtained immediately before and 15, 30, 45 and 60 min after the test meal. The plasma amino acid analysis was performed by a reversed-phase high-performance liquid chromatography based on o-phthaldialdehyde/2-mercaptoethanol pre-column derivatization. In both groups, the plasma amino acid concentrations increased within the first 30 min and the levels did not return to the preprandial baseline during the observation period. Fifteen minutes after the test meal, the plasma levels of all essential amino acids with the exception of histidine were higher in the bovine milk formula fed infants than in the fortified breast milk fed infants. The sum of plasma essential amino acid levels found in the formula fed infants were significantly (p < 0.05) higher than the levels found in the fortified breast milk fed infants at 15, 30 and 45 min. The kinetics of individual amino acids were influenced by the different quality of the protein even when the intakes in the groups were similar, as demonstrated for histidine and phenylalanine. The data indicate that postprandial plasma amino acid concentrations depend significantly on the dietary amino acid source and cannot simply be calculated from the amino acid composition of dietary proteins. Therefore, postprandial plasma amino acid concentrations should be included in the nutritional evaluation of dietary proteins in preterm infants.

Effect of increasing dietary threonine intakes on amino acid metabolism of the central nervous system and peripheral tissues in growing rats

The threonine content of most of the infant formulas currently on the market is approximately 20% higher than the threonine concentration in human milk. Due to this high threonine content the plasma threonine concentrations are up to twice as high in premature infants fed these formulas than in infants fed human milk. To study the effect of different threonine intakes on plasma and tissue amino acid concentrations, 24 young male Wistar rats were fed three experimental diets based on a mixture of bovine proteins with a whey protein/casein ratio of 60/40 with different threonine contents [group A, 0.86 g of threonine/100 g (n = 8); group B, 1.03 g of threonine/100 g (n = 8); group C, 2.21 g of threonine/100 g (n = 8)]. Eight animals were fed a typical rat diet based on bovine casein as controls. After a feeding period of 15 d, amino acids were measured in plasma and in homogenates of the cerebral cortex, brain stem, liver, and muscle. There was a significant correlation between threonine intake and plasma threonine levels (r = 0.687, p < 0.001). The plasma threonine concentration correlated significantly with the threonine concentration in the cortex (r = 0.821, p < 0.01) and the brain stem (r = 0.882, p < 0.01). There was a positive significant correlation between threonine and glycine concentrations in the cortex (r = 0.673, p < 0.01), and the brain stem (r = 0.575, p < 0.01), whereas the glycine concentration decreased with increasing threonine intakes in the liver and muscle. The presented data indicate that increasing the threonine in plasma leads to increasing brain glycine and thereby affects the neurotransmitter balance in the brain. This may have consequences for brain development during early postnatal life. Therefore, excessive threonine intake during infant feeding should be avoided.

Magnetic resonance imaging of the foot. Rheumatologic disorders mimicking osteomyelitis

The authors highlight the importance of close clinical and radiologic correlation in patients with either known rheumatologic conditions or with increased risk factors for rheumatoid arthritides. Some rheumatoid conditions may mimic osteomyelitis.

Neuropathy secondary to pigmented villonodular synovitis of the hip

Pigmented villonodular synovitis is a benign proliferative process of unknown origin that may cause extensive bone and joint destruction. Patients with this condition typically present with symptoms of mild discomfort and associated stiffness of the involved joint; however, the spectrum of presentations is broad. Although pigmented villonodular synovitis begins in, and usually is confined within, a synovium-lined joint, it may extend beyond the joint capsule and present as a soft tissue mass. Three cases of a previously unrecognized presentation of pigmented villonodular synovitis of the hip joint are presented. The authors believe these to be the first reported cases in the English language literature of pigmented villonodular synovitis of the hip seen with femoral or sciatic neuropathy.