Corrination of a GLP-1 Receptor Agonist for Glycemic Control without Emesis

Glucagon-like peptide-1 receptor (GLP-1R) agonists used to treat type 2 diabetes mellitus often produce nausea, vomiting, and in some patients, undesired anorexia. Notably, these behavioral effects are caused by direct central GLP-1R activation. Herein, we describe the creation of a GLP-1R agonist conjugate with modified brain penetrance that enhances GLP-1R-mediated glycemic control without inducing vomiting. Covalent attachment of the GLP-1R agonist exendin-4 (Ex4) to dicyanocobinamide (Cbi), a corrin ring containing precursor of vitamin B12, produces a "corrinated" Ex4 construct (Cbi-Ex4). Data collected in the musk shrew (Suncus murinus), an emetic mammal, reveal beneficial effects of Cbi-Ex4 relative to Ex4, as evidenced by improvements in glycemic responses in glucose tolerance tests and a profound reduction of emetic events. Our findings highlight the potential for clinical use of Cbi-Ex4 for millions of patients seeking improved glycemic control without common side effects (e.g., emesis) characteristic of current GLP-1 therapeutics.

Plasma Vitamin B12 Levels, High-Dose Vitamin B12 Treatment, and Risk of Dementia

Background:

It is controversial whether B12 deficiency causes dementia or B12 treatment can prevent dementia.

Objective:

To assess associations between low plasma (P-)B12 levels, B12 treatment, and risk of Alzheimer’s disease (AD; primary outcome) and all-cause or vascular dementia (secondary outcomes).

Methods:

We conducted a population-based cohort study using Danish registry data to assess associations between low P-B12 levels, high-dose injection or oral B12 treatment, and risk of dementia (study period 2000–2013). The primary P-B12 cohort included patients with a first-time P-B12 measurement whose subsequent B12 treatment was recorded. The secondary B12 treatment cohort included patients with a first-time B12 prescription and P-B12 measurement within one year before this prescription. For both cohorts, patients with low P-B12 levels (<200 pmol/L) were propensity score-matched 1:1 with patients with normal levels (200–600 pmol/L). We used multivariable Cox regression to compute 0–15-year hazard ratios for dementia.

Results:

For low P-B12 and normal P-B12 level groups, we included 53,089 patients in the primary P-B12 cohort and 13,656 patients in the secondary B12 treatment cohort. In the P-B12 cohort, hazard ratios for AD centered around one, regardless of follow-up period or treatment during follow-up. In the B12 treatment cohort, risk of AD was unaffected by low pre-treatment P-B12 levels, follow-up period and type of B12 treatment. Findings were similar for all-cause and vascular dementia.

Conclusion:

We found no associatio1n between low P-B12 levels and dementia. Associations were unaffected by B12 treatment. Results do not support routine screening for B12 deficiency in patients with suspected dementia.

Does a Conjugation Site Affect Transport of Vitamin B12 -Peptide Nucleic Acid Conjugates into Bacterial Cells?

Gram-negative bacteria develop specific systems for the uptake of scarce nutrients, including vitamin B₁₂ . These uptake pathways may be utilized for the delivery of biologically relevant molecules into cells. Indeed, it was recently reported that vitamin B₁₂ transported an antisense peptide nucleic acid (PNA) into Escherichia coli and Salmonella Typhimurium cells. The present studies indicate that the conjugation site of PNA to vitamin B₁₂ has an impact on PNA transport into bacterial cells. Toward this end, a specifically designed PNA oligomer has been tethered at various positions of vitamin B₁₂ (central Co, R_5' -OH, c and e amide chains, meso position, and at the hydroxy group of cobinamide) by using known or newly developed methodologies and tested for the uptake of the synthesized conjugates by E. coli. Compounds in which the PNA oligonucleotide was anchored at the R_5' -OH position were transported more efficiently than that of other compounds tethered at the peripheral positions around the corrin ring. Of importance is the fact that, contrary to mammalian organisms, E. coli also takes up cobinamide, which is an incomplete corrinoid. This selectivity opens up ways to fight bacterial infections.

Trefoil factors (TFFs) are increased in bronchioalveolar lavage fluid from patients with chronic obstructive lung disease (COPD)

Trefoil factors (TFFs) 1, 2 and 3 are small polypeptides that are co-secreted with mucin throughout the body. They are up-regulated in cancer and inflammatory processes in the gastrointestinal system, where they are proposed to be involved in tissue regeneration, proliferation and protection. Our aim was to explore their presence in pulmonary secretions and to investigate whether they are up-regulated in pulmonary diseases characterized by mucin hypersecretion. Bronchioalveolar lavage fluid was obtained from 92 individuals referred to bronchoscopy. The patients were grouped according to diagnosis and pulmonary function. The concentrations of TFF1, TFF2 and TFF3 were measured by ELISA. All three peptides were detected in bronchioalveolar lavage fluid. Patients with chronic obstructive pulmonary disease had concentrations two to three times above the levels in the healthy reference group, and patients with pulmonary malignancies had concentrations of TFF1 and TFF2 three times that of the reference group. The results suggest that TFFs are involved in tissue regeneration, proliferation and protection in lung diseases.

A soluble form of the macrophage-related mannose receptor (MR/CD206) is present in human serum and elevated in critical illness

BACKGROUND

This study tests the hypothesis that the mannose receptor (MR/CD206), which is expressed primarily by macrophages and dendritic cells, can be found in a soluble form (sMR, sMR) in human serum. Furthermore, we wished to establish and validate an enzyme-linked immunosorbent assay (ELISA) for sMR and to perform initial studies exploring the potential of sMR as a biomarker.

METHODS

Western blotting identified a single band of approximately 170 kDa in human serum, and MALDI MS/MS of the purified protein confirmed it to be sMR. An ELISA was established and validated with a measurement range of 1-256 µg/L.

RESULTS

The 95% reference interval was 0.10-0.43 mg/L based on measurements of serum samples from healthy individuals (n=217). Samples from hospitalised patients (n=219) revealed that more than 50% of patients had concentrations above 0.43 mg/L. Very high concentrations (up to 6.2 mg/L) were observed in critically ill patients with sepsis and/or severe liver disease.

CONCLUSIONS

This study documents, for the first time, the presence of sMR in human serum and describes an optimised ELISA suitable for quantitative measurements. Levels of sMR are strongly elevated in several disease states, including sepsis and liver disease, and the protein therefore shows promise as a new biomarker.

Trefoil factor peptides in serum and sputum from subjects with asthma and COPD

OBJECTIVE

Trefoil factor peptides (TFF) are secreted onto mucosal surfaces together with mucins and occur in high concentrations in pulmonary secretions from patients with chronic obstructive pulmonary disease (COPD). In the present study, we aimed to explore the concentrations of the peptides in serum and sputum in patients with COPD.

MATERIALS AND METHODS

Thirty-five individuals were included in the study, including 11 healthy individuals, 13 indivials with asthma and 11 individuals with COPD. TFF1, TFF2 and TFF3 were measured by enzyme-linked immunosorbent assay (ELISA) in sputum induced by hypertonic saline inhalation and in serum. Total protein content in sputum was also determined.

RESULTS

In the sputum samples from COPD patients, we observed an eightfold higher concentration of TFF1 and a fivefold higher concentration of TFF3 compared with controls. In the serum samples from COPD patients, we observed three-, three- and twofold higher concentrations of TFF1, TFF2 and TFF3 respectively compared with controls.

CONCLUSIONS

There is increased secretion of TFF peptides in the lungs of patients with COPD, as well as significant increases in serum levels. This suggests a role for TFF peptides in the pathogenesis of pulmonary diseases with mucus hypersecretion.

[Treatment response in vitamin B12 deficiency depends on the chosen vitamin B12 preparation]

In Denmark, patients with vitamin B12 deficiency are usually treated for life with either Betolvex or Vibeden given as injections every third month. This case report describes a patient who received injections with vitamin B12 prescribed in Germany. The drug prescribed was not available in Denmark; hence the treatment was unsuccessful after the patient returned to Denmark. This led to extensive diagnosing before the cause for the inadequate treatment was found. It illustrates that different vitamin B12 drugs may result in different treatment outcomes, and that caution should be taken when treating patients with vitamin B12 drugs from other countries.

Transcobalamin polymorphism 67A->G, but not 776C->G, affects serum holotranscobalamin in a cohort of healthy middle-aged men and women

Two polymorphic variants in the gene coding for transcobalamin II (TCN2), TCN2 776C- > G and TCN2 67A- > G, may alter serum holotranscobalamin (holoTC), which in turn may affect cellular uptake of cobalamin (Cbl) and thereby Cbl status indicators. We studied the effects of TCN2 776C- > G and TCN2 67A- > G on blood concentrations of holoTC, Cbl, methylmalonic acid (MMA), and total homocysteine (tHcy) in 2411 individuals (50-64 y) that had been selected on the basis of these TCN2 genotypes from 10601 Norwegian inhabitants. The serum holoTC concentration was lower in TCN2 67AG (55 ± 0.75 pmol/L) and 67GG (48 ± 2.14 pmol/L) than in 67AA (62 ± 0.67 pmol/L) (P < 0.001) but did not differ among TCN2 776C- > G genotypes. The polymorphisms interacted as serum holoTC determinants (P = 0.001) and the presence of TCN2 67AG and GG in strata of 776CC and CG, but not 776GG, increased the risk of having serum holoTC < 45.6 pmol/L [tertile 1 vs. tertiles 2 and 3: OR = 2.5 (95% CI 1.8-3.5) for 67AG; OR = 5.7 (95% CI 3.5-9.1) for 67GG in 776CC; OR = 2.1 (95% CI 1.6-2.9) for 67AG; and OR = 4.5 (95% CI 2.4-8.2) for 67GG in 776CG; all P < 0.001]. Plasma MMA, tHcy, and Cbl were not affected by either polymorphism. In summary, serum holoTC, but not plasma Cbl, MMA, or tHcy, varied according to TCN2 67A- > G genotypes. It remains to be determined whether this polymorphic effect on serum holoTC alters its diagnostic utility as Cbl status indicator.

Effect of the vitamin B12-binding protein haptocorrin present in human milk on a panel of commensal and pathogenic bacteria

Background

Haptocorrin is a vitamin B12-binding protein present in high amounts in different body fluids including human milk. Haptocorrin has previously been shown to inhibit the growth of specific E. coli strains, and the aim of the present study was to elucidate whether the antibacterial properties of this protein may exert a general defense against pathogens and/or affect the composition of the developing microbiota in the gastrointestinal tracts of breastfed infants.

Findings

The present work was the first systematic study of the effect of haptocorrin on bacterial growth, and included 34 commensal and pathogenic bacteria to which infants are likely to be exposed. Well-diffusion assays addressing antibacterial effects were performed with human milk, haptocorrin-free human milk, porcine holo-haptocorrin (saturated with B-12) and human apo-haptocorrin (unsaturated). Human milk inhibited the growth of S. thermophilus and the pathogenic strains L. monocytogenes LO28, L. monocytogenes 4446 and L. monocytogenes 7291, but the inhibition could not be ascribed to haptocorrin. Human apo-haptocorrin inhibited the growth of only a single bacterial strain (Bifidobacterium breve), while porcine holo-haptocorrin did not show any inhibitory effect.

Conclusions

Our results suggest that haptocorrin does not have a general antibacterial activity, and thereby contradict the existing hypothesis implicating such an effect. The study contributes to the knowledge on the potential impact of breastfeeding on the establishment of a healthy microbiota in infants.

Promoter hypomethylation and upregulation of trefoil factors in prostate cancer

Trefoil factors, mucin-associated peptides, are overexpressed in prostate cancer (PC). We hypothesized that promoter methylation contributes to the regulation of trefoil factors (TFF1, TFF2 and TFF3) in human prostate cells. Here we show hypomethylation of promoter regions of TFF1 and TFF3 in PC cell lines with significant TFF expression as compared to benign immortalized prostate cell lines and PC cell lines not expressing trefoil factor. The most striking difference was observed for CpG sites located close to the AUG start codon overlapping several putative binding sites for cellular transcription factors. TFF2 was hypermethylated and had no or very low expression in all prostate cell lines investigated. Treatment of methylated cell lines with 5-aza-2'-deoxycytidine restored TFF expression in cell lines not expressing TFF and increased expression significantly in low-expressing cell lines. In clinical samples, methylation of the promoter/enhancer regions of TFF1 and TFF3 was significantly lower in PC compared to benign prostatic hyperplasia. The present study shows an inverse relation between promoter methylation and expression of trefoil factors. Preliminary analysis on clinical samples suggests that this regulatory mechanism is responsible for the increased levels of TFF1 and TFF3 observed in PC. The overexpression and promoter hypomethylation of trefoil factors may serve as biomarkers in PC.

Health technology assessment in clinical biochemistry. Methylmalonic acid: a Danish showcase

In 1992 plasma methylmalonic acid (MMA) was introduced in Denmark for diagnosing vitamin B-12 deficiency. Now, 10 years later, we report on a health technology assessment (HTA) suggesting that the clinical usefulness of MMA is uncertain. MMA is an obvious component for measurement in the diagnosis of vitamin B-12 deficiency because MMA accumulates when there is a lack of vitamin B-12, and technologically the analysis is of high quality. The diagnostic sensitivity of MMA is high, whereas the diagnostic specificity is debatable, and our results suggest it to be relatively low. The organizational aspect implies that both MMA and P-cobalamins have been increasingly employed, though no consensus on the use of the analyses has emerged. The benefit to the patient is not obvious. An increased level of MMA does not predict further increases over time, and vitamin B-12 treatment shows limited clinical benefit in individuals with a moderately increased MMA. The economic consequences of introducing MMA were an increase in the costs of MMA and P-cobalamins of 12% per year during 1992-2000 and an increase in the turnover of vitamin B-12 preparations of 9% per year. In conclusion, MMA was introduced on sound grounds for both pathophysiological considerations and analytical quality. Our HTA shows that the resources employed to diagnose and to treat vitamin B-12 deficiency have increased considerably, but yet we have no evidence to suggest the clinical benefit.

Pharmacokinetics of trefoil peptides and their stability in gastrointestinal contents

Trefoil factor family (TFF) peptides are considered promising for therapeutic use in gastrointestinal diseases, and there is a need to explore the fate of injected TFF and the stability of the peptides in the gastrointestinal tract. We studied the pharmacokinetics of intravenously (i.v.) administered hTFF2 in mice and rats and of hTFF3 administered i.v., intramuscularly, intraperitoneally, and subcutaneously in mice, and estimated by ELISA the decay of the peptides added to rat and human gastrointestinal contents. We found that i.v. injected hTFF2 and hTFF3 were cleared from the circulation within 2-3h, exhibiting comparable pharmacokinetic profiles. In contents from the rat stomach, hTFF levels remained unchanged for up to 6 days. In the small and large intestine of rats, the hTFF levels decreased markedly after 4 and 1h, respectively. In small intestinal contents from humans, the levels remained stable for more than 24h. We conclude that systemically administered hTFF2 and hTFF3 are rapidly eliminated from the circulation and that the stability of hTFF2 and hTFF3 in GI contents appeared higher in the gastric and small intestinal milieu than in the large intestine and feces, suggesting a higher stability toward gastric acid and digestive enzymes than toward microbial degradation.

Mechanisms of discrimination between cobalamins and their natural analogues during their binding to the specific B12-transporting proteins

Three proteins, intrinsic factor (IF), transcobalamin (TC), and haptocorrin (HC), all have an extremely high affinity for the cobalamins (Cbls, Kd approximately 5 fM) but discriminate these physiological ligands from Cbl analogues with different efficiencies decreasing in the following order: IF > TC > HC. We investigated interactions of these proteins with a number of ligands: Cbl, fluorescent conjugate CBC, two base-off analogues [pseudo-coenzyme B12 (pB) and adenosyl factor A (fA)], and a baseless corrinoid cobinamide. Protein-ligand encounter and the following internal rearrangements in both molecules were registered as a change in the fluorescence of CBC (alone or mixed with other ligands), a transition in absorbance of pB and fA (base-off --> on-base conversion), and alterations in the molecular mass of two split IF domains. The greater complexity of the binding kinetics followed better Cbl specificity (HC < TC < IF). On the basis of the experimental results, we propose a general binding model with three major steps: (1) initial attachment of the ligand to the high-affinity C-domain, (2) primary assembly of N- and C-domains, and (3) slow adjustments and fixation of the ligand at the domain-domain interface. Since step 3 was characteristic of highly specific TC and especially IF, we suggest its particular importance for ligand recognition. The designed models revealed the absolute Kd values for a group of analogues. Calculations show that most of them could potentially bind to the specific transporters IF and TC under physiological conditions. Implications of this finding and the protective role of HC are discussed.

Serum trefoil factors in patients with inflammatory bowel disease

BACKGROUND

Trefoil factors (TFF1-3) play a critical role in mucosal protection and repair in the gastrointestinal tract. The aims of the present study were to examine associations between serum TFF1-3 and clinical and biochemical markers reflecting disease activity and to examine changes in TFF1-3 in patients with inflammatory bowel disease (IBD) before and during high-dose prednisolone treatment and tapering.

METHODS

Serum concentrations of TFF1-3 were quantified in 48 ulcerative colitis (UC) and 50 Crohn's disease (CD) patients with little or moderate activity. Additionally, serum TFF concentrations were determined in patients with severe activity in colon IBD (4 UC and 6 CD) before and during prednisolone treatment with 7 healthy subjects as controls.

RESULTS

Median concentrations of TFF1, TFF2, and TFF3 were significantly increased in IBD patients compared with healthy controls (p < 0.01). TFF3 concentrations correlated with clinical and biochemical parameters of disease activity in UC patients. In addition, a trend towards reduction in TFF concentrations during treatment with prednisolone and concomitant clinical and biochemical remission was observed.

CONCLUSIONS

The present data support the concept that trefoil peptides are upregulated and may play a role in IBD mucosal protection and repair. In UC patients, TFF3 levels were increased in active disease levels correlated with disease activity indices. Due to a large variation, serum TFFs are not a potential marker for disease activity.

Expression of the epidermal growth factor system in endometrioid endometrial cancer

OBJECTIVE

The Epidermal Growth Factor (EGF) system is expressed in healthy premenopausal endometrium. We describe the expression of the four receptors, HER1, HER2, HER3, HER4 and the six ligands amphiregulin, transforming growth factor alpha (TGF-alpha), heparin binding EGF like growth factor (HB-EGF), betacellulin, epiregulin and EGF in endometrioid endometrial cancer.

METHODS

We have uterine samples from 45 women with endometrioid endometrial cancer. As normal counterparts, endometrial samples from thirteen postmenopausal women, and previous data on fourteen premenopausal women were employed. Extracted RNA was analyzed by real-time PCR; the receptors and ligands were localized by immunohistochemistry.

RESULTS

Three receptors (HER1, HER2 and HER4) and two detectable ligands (TGF-alpha and HB-EGF) are expressed significantly higher in endometrial cancer than in healthy postmenopausal endometrium. Cancer tissue show significantly lower expression of HER1 and HER3, and higher expression of HER4, amphiregulin, TGF-alpha and HB-EGF compared to premenopausal endometrium; no difference is seen in HER2. EGF is undetectable in all of the samples. Immunohistochemically the receptors locate to the epithelium and/or glands while the ligands locate to the stroma (amphiregulin), the stroma and the epithelium (TGF-alpha, epiregulin), the epithelium (betacellulin) or are not detectable (HB-EGF, EGF).

CONCLUSIONS

mRNA of all receptors and five ligands are present in endometrioid endometrial cancer, and the protein of all receptors and four ligands are identified by immunohistochemistry. The expression pattern in endometrioid endometrial cancer differs from the pattern in pre- and postmenopausal endometrium. The most remarkable finding is an increased level of HER4, a receptor which correlates to a favorable prognosis in other types of cancers.

Trefoil factors are expressed in human and rat endocrine pancreas: differential regulation by growth hormone

Trefoil factors (TFFs) 1, 2, and 3 are expressed in mucosal epithelia. TFFs are particular abundant in the intestine in which they play a crucial role in maintenance and restitution of the epithelium. Because pancreas developmentally arises from the primitive foregut, we explored the expression of TFFs in the pancreas in man and rat. Immunocytochemical staining of adult human pancreas showed abundant TFF3 immunoreactivity in pancreatic islets and some duct cells, whereas weak TFF1 and no TFF2 staining were detected. In the islets TFF3 localized to most insulin and some glucagon and pancreatic polypeptide-producing cells. TFF3 immunoreactivity was colocalized with insulin and glucagon in distinct cell clusters in human fetal pancreas at wk 14 and in the newborn rat pancreas. In isolated human and rat islets, TFF3 and TFF1 mRNA was identified by RT-PCR, and TFF3 protein was detected in human pancreas and islets by ELISA. Exposure of neonatal rat islets or insulinoma cells to GH, a known beta-cell growth factor, resulted in markedly increased TFF3 but decreased TFF1 mRNA levels. The effect of GH on TFF3 expression was confirmed by Western blot. Culture of neonatal rat islets in the presence of TFF3 resulted in attachment and migration of the islet cells, but no effects on proliferation, insulin secretion or cytokine-induced apoptosis were seen. These data demonstrate expression of TFFs in the endocrine pancreas, but their possible functions remain unknown.

Macrophage serum markers in pneumococcal bacteremia: Prediction of survival by soluble CD163

OBJECTIVE

Soluble CD163 (sCD163) is a new macrophage-specific serum marker. This study investigated sCD163 and other markers of macrophage activation (neopterin, ferritin, transcobalamin, and soluble urokinase plasminogen activator receptor [suPAR]) as prognostic factors in patients with pneumococcal bacteremia.

DESIGN

Observational cohort study.

SETTING

Five university hospitals in Denmark.

PATIENTS

A total of 133 patients with Streptococcus pneumoniae bacteremia (positive blood culture) and 133 age- and gender-matched controls.

INTERVENTIONS

Samples were collected for biochemical analyses at the time of first positive blood culture.

MEASUREMENTS AND MAIN RESULTS

sCD163 was highly correlated with other macrophage markers and was significantly elevated (median [25-75 percentiles], 4.6 mg/L [2.8-8.9]) compared with healthy controls (2.7 mg/L [2.1-3.3], p < .0001). Increased levels were observed in patients who needed intensive care (hemodialysis, p = .0011; hypotension, p = .0014; mechanical ventilation, p = .0019). Significantly lower levels of sCD163, ferritin, transcobalamin, and suPAR (but not C-reactive protein) were measured in patients > or =75 yrs. In patients <75 yrs, all macrophage markers were increased in patients who died from their infection compared with survivors, whereas no change was observed in any of the markers in the very old age. At cutoff levels of 9.5 mg/L (sCD163) and 1650 nmol/L (C-reactive protein), the relative risk for fatal outcome in patients <75 yrs was 10.1 (95% confidence interval 3.4-31.0) and 7.0 (95% confidence interval 2.4-21.6) for sCD163 and C-reactive protein, respectively. In a multivariate logistic regression model for patients <75 yrs, ferritin, transcobalamin, neopterin, and suPAR contained no significant information on the probability of survival when sCD163 and CRP were known (p = .25).

CONCLUSIONS

Macrophage marker response in pneumococcal bacteremia was compromised in old age. In patients <75 yrs old, sCD163 was superior to other markers, including C-reactive protein, in predicting fatal disease outcome.

Application of a fluorescent cobalamin analogue for analysis of the binding kinetics. A study employing recombinant human transcobalamin and intrinsic factor

Fluorescent probe rhodamine was appended to 5' OH-ribose of cobalamin (Cbl). The prepared conjugate, CBC, bound to the transporting proteins, intrinsic factor (IF) and transcobalamin (TC), responsible for the uptake of Cbl in an organism. Pronounced increase in fluorescence upon CBC attachment facilitated detailed kinetic analysis of Cbl binding. We found that TC had the same affinity for CBC and Cbl (K(d) = 5 x 10(-15) m), whereas interaction of CBC with the highly specific protein IF was more complex. For instance, CBC behaved normally in the partial reactions CBC + IF(30) and CBC + IF(20) when binding to the isolated IF fragments (domains). The ligand could also assemble them into a stable complex IF(30)-CBC-IF(20) with higher fluorescent signal. However, dissociation of IF(30)-CBC-IF(20) and IF-CBC was accelerated by factors of 3 and 20, respectively, when compared to the corresponding Cbl complexes. We suggest that the correct domain-domain interactions are the most important factor during recognition and fixation of the ligands by IF. Dissociation of IF-CBC was biphasic, and existence of multiple protein-analogue complexes with normal and partially corrupted structure may explain this behaviour. The most stable component had K(d) = 1.5 x 10(-13) m, which guarantees the binding of CBC to IF under physiological conditions. The specific intestinal receptor cubilin bound both IF-CBC and IF-Cbl with equal affinity. In conclusion, the fluorescent analogue CBC can be used as a reporting agent in the kinetic studies, moreover, it seems to be applicable for imaging purposes in vivo.

A longitudinal study of serum cobalamins and its binding proteins in lactating women

OBJECTIVE

To examine longitudinal changes in serum cobalamins, transcobalamin (TC) and haptocorrin (HC) during lactation and to investigate the influence of vitamin B12 supplementation on these parameters.

DESIGN

A 9-month follow-up study.

SUBJECTS AND METHODS

Lactating mothers (N=89) including 23 supplemented with vitamin B12 (1-18 microg/daily), 41 partly supplemented and 25 not supplemented. Blood samples collected 3 weeks (baseline) and 4 and 9 months post-partum were analysed for cobalamins, TC and HC. Both the total concentration and the cobalamin-saturated form (holo) of TC and HC were analysed.

RESULTS

No significant differences were observed in serum cobalamins or its binding proteins related to supplementation with vitamin B12 or the duration of lactation. Serum cobalamins remained unchanged from 3 weeks to 9 months post-partum. Total TC (holoTC) (median+/-s.e. pmol/l) decreased between 3 weeks (710+/-23 (85+/-12)) and 9 months (602+/-21 (76+/-11)) (P<0.0001 (P=0.0002)), whereas total HC (holoHC) increased from (422+/-11 (300+/-9)) at 4 months to (455+/-13 (317+/-10)) to 9 months post-partum (P<0.0001 (P<0.0001)).

CONCLUSION

We report a decrease in TC and an increase in HC during a 9-month period post-partum. No differences were observed between the vitamin B12-supplemented and the unsupplemented groups. Thus, supplementation with vitamin B12 has no impact on the circulating level of serum cobalamins or its binding proteins in a Danish population of lactating mothers.

Systemically administered trefoil factors are secreted into the gastric lumen and increase the viscosity of gastric contents

BACKGROUND AND PURPOSE

Trefoil factors (TFFs) secreted by mucus-producing cells are essential for the defence of the gastrointestinal mucosa. TFFs probably influence the viscoelastic properties of mucus, but this has not been demonstrated in vivo. We therefore studied the gastric secretion of systemically administered TFF2 and TFF3, and their influence on the viscosity of the secretions.

EXPERIMENTAL APPROACH

Mice and rats under general anaesthesia were injected intravenously with human (h) TFF2, hTFF3 (5 mg kg(-1) to mice and 25 mg kg(-1) to rats), murine (m) (125)I-TFF3, or (125)I-hTFF3 (300,000 cpm, mice only). The appearance of TFFs in the gastric mucosa and luminal secretions was analysed by autoradiography, gamma-counting, and ELISA, and the viscosity by rheometry.

KEY RESULTS

(125)I-mTFF3 and (125)I-hTFF3 were taken up by secretory cells of the gastrointestinal tract and detected at the gastric mucosal surface 15 min after injection. Stressing the stomach by carbachol (3.5 microg kg(-1)) and pyloric ligation significantly increased the uptake. Injected hTFF2, hTFF3, and mTFF3 were retrieved from the gastric contents after 4 h. In rats, an approximately seven-fold increase in the viscosity was detected after injection of TFF2 compared to the controls, whereas TFF3 did not increase the viscosity. In mice, TFF2 increased the viscosity approximately 4-fold.

CONCLUSIONS

These data indicate that systemically administered TFFs are transferred to the gastric lumen in a biologically active form.

Plasma levels of trefoil factors are increased in patients with advanced prostate cancer

PURPOSE

Through cDNA array analyses and immunohistochemistry on tissue microarrays, trefoil factor 3 (TFF3) was recently shown to be overexpressed in prostate cancer. The purpose of this study was to test the feasibility of using the levels of trefoil factors as a plasma marker for prostate cancer.

EXPERIMENTAL DESIGN

In 79 patients with prostate cancer, 23 patients with benign prostatic hyperplasia, and 44 healthy individuals plasma TFF1, TFF2, and TFF3 were determined with ELISAs and compared with clinical stage and prostate-specific antigen (PSA) values. Plasma levels of TFF were compared with the immunohistochemical expression of TFF and chromogranin A in 30 prostate cancer tissue samples.

RESULTS

Patients with advanced prostate cancer had significantly higher plasma concentrations of TFF1, TFF2, and TFF3 (P < 0.01) compared with patients with localized disease. Using a cutoff of 200 pmol/L, the sensitivity and specificity of plasma TFF3 in differentiating between patients with localized and advanced disease was 74% (59-85%) and 81% (66-91%). Plasma levels of TFF3 were highest in patients with bone metastases (P = 0.008). Patients with serum PSA >10 microg/L had significantly higher plasma TFF3 values than patients with serum PSA <10 microg/L (P = 0.03) and TFF3 levels were higher in patients with Gleason sums of > or = 7 (P = 0.02). Expression of TFF1 and TFF3 determined by immunohistochemistry was increased in patients with prostate cancer but did not correlate with plasma trefoil factor values.

CONCLUSIONS

Plasma levels of trefoil factors are increased in patients with advanced prostate cancer. Prospective studies are needed to confirm the predictive utility of trefoil factors in prostate cancer.

Effect of Vitamin B12 Treatment on Haptocorrin

Background: Haptocorrin (HC) carries the major part of circulating cobalamin, but whether HC is altered on treatment with vitamin B12 remains unknown.

Methods: Our study included 3 populations: a population of vegan men (n = 174; vegan population), of whom 63 were treated daily with 5 mg of oral vitamin B12 for 3 months; a group of patients with a previous methylmalonic acid (MMA) concentration &gt;0.4 μmol/L (n = 140; population with suspected deficiency), of which 69 were treated with weekly vitamin B12 injections (1 mg) for 4 weeks; and a subgroup of participants in a vitamin B intervention study (n = 88; nondeficient population), of whom 45 were treated daily with 0.4 mg of oral vitamin B12 for 3 months. Total HC and holoHC were measured by ELISA. Cobalamin was measured by an intrinsic factor (IF)-based assay. Samples were collected at baseline and 3 months after start of treatment.

Results: Compared with baseline results for the 3 study populations, total HC and holoHC increased 30 pmol/L for every 100 pmol/L increase in cobalamin. After treatment with vitamin B12, holoHC (P &lt;0.0001) and total HC (P &lt;0.0001) increased significantly in the vegan population. Only holoHC increased in the population with suspected deficiency (P &lt;0.0001), whereas no alteration was observed in the nondeficient population.

Conclusions: The HC concentration is decreased in severely cobalamin-deficient individuals and increases on treatment. The concentration of cobalamin also relates significantly to the HC concentration in nondeficient individuals.

A daily intake of approximately 6 microg vitamin B-12 appears to saturate all the vitamin B-12-related variables in Danish postmenopausal women

BACKGROUND

Recommended daily intakes of vitamin B-12 vary between 2 and 6 microg.

OBJECTIVE

The objective was to examine the associations between vitamin B-12 intake and markers of vitamin B-12 deficiency.

DESIGN

We studied 98 Danish postmenopausal women aged 41-75 y. Serum cobalamin, transcobalamin (TC) saturated with vitamin B-12 (holo-TC), TC saturation (holo-TC/total TC), methylmalonic acid (MMA), and total homocysteine (tHcy) were measured to assess vitamin B-12 status. Dietary intakes of vitamin B-12 were determined from 7-d weighed food records. Gastric pH measurement and the alkali-challenge test were performed with the use of Heidelberg radiotelemetric capsules.

RESULTS

The total intake of vitamin B-12 ranged from 1.2 to 23.9 microg/d. All vitamin B-12-related variables, except gastric pH, correlated significantly with total vitamin B-12 intake. Those taking supplements (54%) had higher circulating concentrations of cobalamin and TC saturation and lower concentrations of MMA and tHcy than did those not taking supplements. All subjects were divided into quintiles according to their total vitamin B-12 intake. For all the variables analyzed, the curves appeared to level off at a daily vitamin B-12 intake of approximately 6 microg; the median (and 25th-75th percentiles) for cobalamin was 380 (270-480) pmol/L, for holo-TC was 119 (92-162) pmol/L, for MMA was 0.12 (0.14-0.17) micromol/L, and for tHcy was 9.75 (8.3-11.40) micromol/L (n = 58).

CONCLUSION

A daily vitamin B-12 intake of 6 microg appeared to be sufficient to correct all the vitamin B-12-related variables measured in the postmenopausal Danish women in this study.

Folate and vitamin B12 in relation to lactation: a 9-month postpartum follow-up study

OBJECTIVE

To investigate the relation between lactation and markers of folate and vitamin B12 (B12) deficiency in women with and without vitamin supplementation.

DESIGN

A 9-month follow-up study.

SUBJECTS AND METHODS

Blood samples from 91 women, who gave birth to a single healthy child, were collected 3 weeks, 4 and 9 months postpartum and analysed for circulating level of homocysteine (tHcy), methylmalonic acid (MMA), folate and B12. The participants were categorized as exclusively, partly or not breast-feeding dependent on the degree of lactation 4 months postpartum. During follow-up, lifestyle factors were recorded by structured interviews.

RESULTS

Among 72 exclusively breast-feeding women, the median (10-90% percentile) tHcy was 5.8 (3.1-8.3) micromol/l 3 weeks postpartum, 6.1 (4.1-10.3) micromol/l 4 months postpartum and 5.3 (3.6-8.7) micromol/I 9 months postpartum. At 9 months postpartum, none of the women breast-fed exclusively. No significant change occurred in the concentration of B12 and folate. Exclusively breast-feeding women without vitamin supplementation had higher median tHcy than supplemented exclusively breast-feeding women 4 and 9 months postpartum (7.0 vs 5.4 micromol/l (P < 0.001) and 5.8 vs 4.5 micromol/l (P = 0.003), respectively). Six women had increased (>15 micromol/l) tHcy; four of these were unsupplemented and exclusively breast-feeding.

CONCLUSION

We found no overall indication of depletion of the folate and B12 stores during the lactation period in this population. However, folate-supplemented women had lower tHcy and higher folate levels, suggesting a beneficial effect of supplementation with folate throughout lactation.

Expression of the epidermal growth factor system in human endometrium during the menstrual cycle

The epidermal growth factor (EGF) system is ubiquitous in humans and plays fundamental roles in embryogenesis, development, proliferation and differentiation. As the endometrium of fertile women is characterized by proliferation and differentiation, we hypothesize a role for the EGF system. Fourteen premenopausal women had endometrial samples removed on day 6 +/- 1 and day 6 +/- 1 and 12 +/- 1 after ovulation during one menstrual cycle. RNA was extracted and analysed by real-time PCR, and immunohistochemistry was performed to localize the components of the EGF system. Human EGF Receptor 1 (HER1) showed highest expression during the proliferative phase, HER2 and HER4 during the early and HER3 during the late secretory phase. Amphiregulin (AR) and transforming growth factor alpha (TGFalpha) expression is highest in proliferative phase. Heparin binding (HB)-EGF and betacellulin (BCL) show no variation. Epiregulin (EP) is detectable in some samples. EGF is undetectable. HER1, HER2, HER3 and HER4 were localized to the epithelium and glands HER3 and HER4 solely in the secretory phase. Amphiregulin was seen in leucocytes and stromal cells, TGFalpha and betacellulin in the epithelial lining, epiregulin in stromal cells whereas HB-EGF and EGF are undetectable. In conclusions, we observed cyclical expression of the four EGF receptors and two ligands and localized all four receptors and four ligands in endometrial biopsies. This suggests a role for the EGF system in growth of the endometrium.

Increase in amphiregulin and epiregulin in prostate cancer xenograft after androgen deprivation-impact of specific HER1 inhibition

BACKGROUND

We investigated the expression of the epidermal growth factor (EGF) network before and after castration in the prostate cancer xenograft CWR22 implanted in nude mice, and examined the effects of gefitinib (Iresssa, ZD1839), a new drug directed towards the EGF tyrosine kinase receptor (HER1) of the EGF network.

METHODS

CWR22 prostate cancer xenografts were propagated in immunodeficient male mice. The expression of the growth factors and receptors in the EGF network was examined by real-time PCR analysis and ELISA at 0, 7, 14, and 30 days after castration, and the tumor growth was examined after treatment with gefitinib or placebo.

RESULTS

A fraction of growth factors showed a steady increase in the mRNA expression reaching between fourfold and eightfold 30 days after castration, including amphiregulin (P < 0.005) and epiregulin (P < 0.001). ELISA for amphiregulin showed a fivefold increase 30 days after castration. Tumor bearing mice were castrated and treated with or without the HER1 tyrosine kinase inhibitor gefitinib. Tumor involution was significantly increased by castration plus gefitinib as compared to castration alone.

CONCLUSIONS

Castration leads to adaptive increase in the concentrations of a subset of growth factors from the EGF network in the androgen sensitive CWR22 prostate cancer xenograft. Specific inhibition of the HER1 tyrosine kinase receptor significantly increases the tumor involution, and suggests that HER1 targeted drugs could be of therapeutic relevance in the treatment of advanced prostate cancer.

Alpha-1--antitrypsin in aqueous humour from patients with corneal allograft rejection

PURPOSE

To investigate the presence and concentration of alpha1-antitrypsin in aqueous humour at the time of corneal rejection and to compare results obtained from patients with reversible and irreversible rejection.

METHODS

Samples of aqueous humour were obtained from 17 patients with acute corneal endothelial allograft rejection. The presence of alpha1-antitrypsin in aqueous humour was confirmed by immunoblotting and measured employing a sandwich ELISA. Total protein concentrations in aqueous humour were measured using Bradford's method. The outcome of corneal rejection episodes was determined 1 month after diagnosing corneal rejection and described as reversible or irreversible rejection.

RESULTS

alpha1-antitrypsin was detected in aqueous humour. Patients with reversible rejection had significantly higher alpha1-antitrypsin concentration than patients with irreversible rejection (p = 0.044). There was no significant difference in total protein concentrations (p = 0.745), and no correlation was found between alpha1-antitrypsin and total protein concentrations (p = 0.368).

CONCLUSIONS

alpha1-antitrypsin in aqueous humour seems to signal a favourable outcome of corneal rejection. The possible mechanism is discussed.

Soluble CD163 and interleukin-6 are increased in aqueous humour from patients with endothelial rejection of corneal grafts

PURPOSE

To evaluate soluble CD163 (sCD163) as a new marker of macrophage activity in aqueous humour from patients with corneal rejection and to investigate correlations between sCD163, the CD163 inducing interleukin-6 (IL-6), and albumin; to investigate whether increases in sCD163 and IL-6 levels in aqueous humour were results of intra- or extraocular production, and to investigate the impact of sCD163 and IL-6 levels on graft outcome.

METHODS

Aqueous humour was obtained from 19 patients with endothelial rejection of corneal grafts, seven cataract patients and five cataract patients with uncomplicated corneal grafts. The presence of sCD163 was investigated by immunoprecipitation and immunoblotting. The concentrations of sCD163, IL-6 and albumin were measured by ELISA.

RESULTS

Soluble CD163 was detected in aqueous humour from patients with corneal rejection. Soluble CD163, IL-6 and albumin were significantly increased in aqueous humour from patients with corneal rejection when compared with control patients. When normalizing sCD163 and IL-6 with albumin, the differences between rejection patients and control groups became insignificant for sCD163 but remained significant for IL-6. Neither IL-6 nor sCD163 were related to the outcome of the corneal rejection.

CONCLUSIONS

Both sCD163 and IL-6 are present in high levels in aqueous humour from patients with rejection of corneal grafts. Our data suggest that IL-6 is produced locally, whereas sCD163 is at least partly derived from influx from plasma.

Composite organization of the cobalamin binding and cubilin recognition sites of intrinsic factor

Intrinsic factor (IF(50)) is a cobalamin (Cbl)-transporting protein of 50 kDa, which can be cleaved into two fragments: the 30 kDa N-terminal peptide IF(30) and the 20 kDa C-terminal glycopeptide IF(20). Experiments on binding of Cbl to IF(30), IF(20), and IF(50) revealed comparable association rate constants (k(+)(Cbl) = 4 x 10(6), 14 x 10(6), and 26 x 10(6) M(-1) s(-1), respectively), but the equilibrium dissociation constants were essentially different (K(Cbl) = 200 microM, 0.2 microM, and <or=1 pM, respectively). The smaller fragment, IF(20), had unexpectedly high affinity for Cbl; however, efficient retention of the ligand required the presence of both fragments. Detailed schemes of the interaction of Cbl with IF(50) and with IF(30) and IF(20) are presented, where the sequential attachment of Cbl to the IF(20) and IF(30) domains plays the key role in recognition and retention of the ligand. Each isolated fragment of IF was tested for the binding to the specific receptor cubilin in the presence or absence of Cbl. Neither apo nor holo forms of IF(20) and IF(30) were recognized by the receptor. When two fragments were mixed and incubated with Cbl, they associated into a stable complex, IF(30+20).Cbl, which bound to cubilin as well as the noncleaved IF(50).Cbl complex. We suggest that formation of the cubilin recognition site on IF is caused by assembly of two distant domains, which allows the saturated protein to be recognized by the receptor. The obtained parameters for ligand and receptor binding indicate that both full-length IF(50) and the fragments may be involved in Cbl assimilation.

Proteomic analysis of aqueous humour from patients with acute corneal rejection

PURPOSE

To compare the basic proteomic composition of aqueous humour (AH) from patients with corneal rejection (patients) with AH from patients with cataract (controls).

METHODS

Aqueous humour was analysed for total protein concentration using Bradford's method and for protein composition using two-dimensional (2D) gel electrophoresis. Image analysis was used to detect protein spots in 2D gels that were increased by more than factor 2 in patients as compared with controls. Increased spots were identified by immunoblotting and mass spectrometry.

RESULTS

Aqueous humour from patients contained significantly higher total protein concentration than did AH from controls. A total of 31 spots were significantly increased in 2D gels from patients. The spots were derived from albumin, alpha1-antitrypsin, apolipoprotein J, cytokeratin type II, serin proteinase inhibitor and transthyretin. After correction of spot volumes by total protein concentrations, 10 spots derived from albumin, cytokeratin type II and alpha1-antitrypsin remained significantly increased.

CONCLUSION

The proteomic composition of AH differed significantly between patients and controls. The identified proteins suggest that the changes in AH are due to at least three different mechanisms: breakdown of the aqueous-blood barrier, enzymatic degradation, and liberation of locally synthesized proteins.

Assembly of the Intrinsic Factor Domains and Oligomerization of the Protein in the Presence of Cobalamin

Human intrinsic factor (IF) was purified from the recombinant plant Arabidopsis thaliana by affinity chromatography. Cobalamin (Cbl) saturated protein was separated by gel filtration into peaks I and II, which contained according to SDS electrophoresis the 50 kDa full-length protein IF(50) and a mixture of two fragments, respectively. Two components of peak II were identified as the 30 kDa N-terminal peptide IF(30) and the 20 kDa C-terminal glycopeptide IF(20). Measurements of M(w) under the nondenaturing conditions were conducted by static light scattering. They revealed 100 kDa IF dimers in peak I, whereas 50 kDa cleaved monomers were found in peak II. The protein devoid of Cbl dissociated to the elementary units incapable of association in the absence of Cbl. The individual proteolytic fragments bound Cbl at high concentration of the ligand; however, neither IF(30).Cbl nor IF(20).Cbl oligomerized. A mixture of two fragments IF(30) + IF(20) and Cbl produced a firm complex, IF(30+20).Cbl, which could not associate to dimers. In contrast to IF(30+20).Cbl, the saturated full-length monomers IF(50).Cbl dimerized with K(d) approximately 1 microM. We suggest a two-domain organization of the full-length protein, where two distant units, IF(30) and IF(20), can be assembled only by Cbl. They are connected by a protease-sensitive link, whose native structure is likely to be important for dimerization. However, linkage between two domains is not compulsory for Cbl binding. Advantages of the two-domain structure of IF are discussed.

Biochemical signs of impaired cobalamin status during and after radiotherapy for rectal cancer

PURPOSE

The aim of the study was to investigate whether pelvic radiotherapy for rectal cancer had a negative impact on cobalamin status.

METHODS AND MATERIALS

Consecutive patients receiving pelvic radiotherapy (50 Gy) for rectal cancer were evaluated prospectively (n = 54). Serum cobalamin, holotranscobalamin (holoTC), methylmalonic acid (MMA), and total homocysteine (tHcy) were measured at start and end of radiotherapy, at follow-up 4-6 weeks and 1 year (n = 23) after radiotherapy.

RESULTS

Mean serum cobalamin decreased from 306 pmol/L before treatment to 267 pmol/L at the end of radiotherapy (p < 0.001), 247 pmol/L 4-6 weeks after radiotherapy (p < 0.001), and 249 pmol/L 1 year after radiotherapy (p = 0.02). Mean serum MMA was 0.16 micromol/L pretreatment, 0.17 micromol/L at the end of radiotherapy (n.s.), and increased to 0.19 micromol/L after 4-6 weeks (p = 0.007), and to 0.21 micromol/L after 1 year (p < 0.001). There was no change in serum tHcy. Mean serum holoTC was reduced from 111 pmol/L pretreatment to 93 pmol/L 4-6 weeks after radiotherapy (p = 0.002).

CONCLUSIONS

The data suggest rapid and persistent decrease in cobalamin status after radiotherapy for rectal cancer, as reflected by reduced serum cobalamin combined with increased serum MMA. This observation, though modest, may motivate routine monitoring of cobalamin status at follow-up after radiotherapy.

Vitamin B6 level is associated with symptoms of depression

BACKGROUND

A low level of vitamin B6 might theoretically cause depression as vitamin B6 is a cofactor in the tryptophan-serotonin pathway. In the present study, we examined the association between depression and the phosphate derivative of vitamin B6 in plasma, pyridoxal phosphate (PLP).

METHODS

In 140 individuals, symptoms of depression were evaluated by the Major Depression Inventory, and biochemical markers of vitamin B deficiency were measured.

RESULTS

We found that 18 (13%) individuals were depressed. A low plasma level of PLP was significantly associated with the depression score (p=0.002). No significant association was found between depression and plasma vitamin B12 (p=0.13), plasma methylmalonic acid (p=0.67), erythrocyte folate (p=0.77), and plasma total homocysteine (p=0.16).

CONCLUSION

Our study suggests that a low level of plasma PLP is associated with symptoms of depression. Randomized trials are now justified and needed in order to examine whether treatment with vitamin B6 may improve symptoms of depression.

Immunoassays of human trefoil factors 1 and 2: measured on serum from patients with inflammatory bowel disease

BACKGROUND

The trefoil factors (TFF1-3) are cysteine-rich peptides expressed in the gastrointestinal tract where they play a critical role in mucosal protection and repair. The expression is up-regulated at sites of ulceration in various chronic inflammatory diseases. Recently, we presented an ELISA method for measurement of TFF3. The aims of the present study were to develop and evaluate ELISAs for the other two known human trefoil peptides, TFF1 and TFF2, and to carry out a cross-sectional study on serum TFF levels in patients with inflammatory bowel disease (IBD).

METHODS

The TFF1-ELISA was based on two polyclonal rabbit antibodies and the TFF2-ELISA on a monoclonal mouse antibody and a polyclonal rabbit antibody. RhTFF1 and 2 were employed to prepare the calibrators. TFF1-3 were assayed in serum from IBD patients (n=41) and controls (n=13).

RESULTS

The TFF1- (TFF2-) ELISA had a detection limit of 3 pmol/L (6 pmol/L) and an analytical imprecision (CV(A)) of 7.0-8.8 for mean concentrations of 24-120 pmol/L (6.1-8.0 for mean concentrations of 17-77 pmol/L). The central reference intervals (n=300) were 140-1400 pmol/L (37-190 pmol/L). There was no variation with age and menstrual cycle. Food intake reduced concentrations of TFF1 by approximately 15%, but did not influence concentrations of TFF2. TFF1 and TFF3 were increased in serum from IBD patients.

CONCLUSIONS

We have developed assays for measuring TFF1 and TFF2. Finding increased TFF concentrations in serum from IBD patients suggests that measurements of trefoil peptides may be of clinical relevance in IBD.

No effect of vitamin B-12 treatment on cognitive function and depression: a randomized placebo controlled study

BACKGROUND

Associations between vitamin B-12 deficiency and impaired cognitive function and depression have been reported.

METHODS

A randomized placebo controlled study including 140 individuals with an increased plasma methylmalonic acid (0.40-2.00 micromol/l) not previously treated with vitamin B-12. Cognitive function was assessed by the Cambridge Cognitive Examination (CAMCOG), Mini-Mental State Examination (MMSE), and a 12-words learning test. Symptoms of depression were evaluated by the Major Depression Inventory. The main outcome measure was change in cognitive function and depression score from baseline to follow-up 3 months later.

RESULTS

At baseline 78 (56%) individuals had cognitive impairment judged from the CAMCOG score and 40 (29%) according to the MMSE; 18 (13%) individuals had symptoms of depression. No improvement was found in cognitive function comparing the treatment and placebo group (total CAMCOG score: P = 0.43), nor among individuals with only slightly impaired cognitive function (n = 44, total CAMCOG score: P = 0.42). The treatment group did not improve in depression score as compared to the placebo group (P = 0.18).

LIMITATIONS

The duration of impaired cognitive function was unknown.

CONCLUSIONS

A high proportion of individuals with an increased plasma methylmalonic acid had impaired cognitive function, and a rather high prevalence of depression was observed. However, vitamin B-12 treatment did not improve cognitive function or symptoms of depression within the 3-months study period.

Holo-Transcobalamin Concentration and Transcobalamin Saturation Reflect Recent Vitamin B12 Absorption Better than Does Serum Vitamin B12

Background: We evaluated whether measurement of vitamin B12-saturated transcobalamin (holo-TC) concentrations or TC saturation (holo-TC:total TC) reflects active vitamin B12 absorption in healthy individuals and patients after vitamin B12 intake.

Methods: We obtained blood samples from 31 healthy individuals (age range, 25–57 years) before (days −1 and 0) and after (days 1, 2, and 6) oral administration of three 9-μg doses of vitamin B12. The blood samples from seven patients (age range, 22–39 years) suspected to have decreased vitamin B12 absorption were obtained before and 1 day after the vitamin B12 intake. The blood samples were analyzed for vitamin B12, total TC, and holo-TC. The TC saturation was calculated.

Results: Intraindividual variation was &lt;13% for all measured values, as calculated from samples removed on day −1 and 0. In healthy individuals (n = 31) after intake of vitamin B12, the maximum median (range) increase (as percentages and absolute values) was in TC saturation [52 (−2% to 128)% and 0.04 (0–0.23) as a fraction], closely followed by holo-TC concentrations [39 (0–108)% and 34 (0–149) pmol/L]. All but one healthy individual had an increase of ≥15% in these markers. Serum vitamin B12 showed a smaller increase [14 (−8 to 51)% and 36 (−27 to 290) pmol/L]. After vitamin B12 intake, three patients with Crohn disease had the lowest increases in holo-TC concentration (3, 7, and 14 pmol/L) and in TC saturation (0.004, 0.01, and 0.01) among patients and 30 healthy individuals.

Conclusion: Holo-TC concentrations and TC saturation reflect normal vitamin B12 absorption better than does serum vitamin B12.

The DNA damaging agent VP16 induces the expression of a subset of ligands from the EGF system in bladder cancer cells, whereas none of the four EGF receptors are induced

Increased activity of the EGF system exerts a cell survival function in the presence of cytotoxic agents. The aim of our investigation was to identify the ligands and receptors from the EGF system, that are induced by the chemotherapeutic DNA damaging agent VP16 in bladder cancer cell lines. By use of real-time RT-PCR assays for all four receptors and six ligands from the EGF system we demonstrate that in HCV29 bladder cancer cells, amphiregulin, HB-EGF, and epiregulin mRNA levels are elevated (more than 100, 5, and 4 fold, respectively) by VP16. The remaining ligands (EGF, TGFalpha and betacellulin) are uninduced. The same was found for T24A bladder cancer cells, except that TGFalpha also was induced. The four receptors were reduced by VP16 in both cell lines. This demonstrates that the induction of the EGF system is mediated by an increased expression of a subset of the ligands, whereas the four receptors are reduced. For amphiregulin and HER1 we investigated with ELISA assays if the effects of VP16 also were observed at the protein level. We found that VP16 increase the amount of amphiregulin peptide both in the cell membrane and the culture medium. Similarly, the reduced EGF receptor mRNA expression correlated with reduced HER1 protein. Several investigations have shown that labile protein factors can be involved in the regulation of stress inducible growth factors and cytokines. We investigated if a labile protein regulates the expression of the subset of ligands that were induced with VP16. Blocking of protein neosynthesis with cycloheximide resulted in induced mRNA expression of exactly the same subset of ligands as observed with VP16 treatment of both HCV29 and T24A cells. This suggests that a labile protein factor regulates either the transcription or degradation of these mRNA's, and it can be speculated that VP16 also operate by inhibiting the activity of this factor. This is further stressed by the observation that combined treatment with cycloheximide and VP16 show no additive effect. In conclusion, we show that a subset of ligands from the EGF system is upregulated by VP16, whereas none of the four receptors are induced. This might represent a physiological response aimed at rescuing the cells.

Injected TFF1 and TFF3 bind to TFF2-immunoreactive cells in the gastrointestinal tract in rats

Peptides of the trefoil factor family (TFF1, TFF2 and TFF3) are co-secreted with mucus in most organ systems and are believed to interact with mucins to produce high-viscosity, stable gel complexes. We have previously demonstrated that cells in the GI tract possess binding sites to TFF2 and that injected TFF2 ends up in the mucus layer. In the present study, tissue binding and metabolism of parenterally administered human TFF1 and TFF3 in rats were described and compared to the immunohistochemical localization of the TFF peptides. 125I-TFF1 monomer and 125I-TFF3 mono- and dimer were given intravenously to female Wistar rats. The tissue distribution was assessed by gamma counting of organ samples and by autoradiography of histological sections. The degradation of 125I-TFF3 was studied by means of trichloracetic acid (TCA) precipitation and the saturability of the binding by administration of excess unlabelled peptide. The TFF peptides were localized in histologic sections from the GI tract by immunohistochemistry. Injected TFF3 dimer (12%) was taken up by the GI tract. At autoradiography, grains were localized to the same cells that were immunoreactive to TFF2. The binding could be displaced by excess TFF3. Similar binding was observed for the TFF1 and TFF3 monomers apart from binding in the stomach, where the uptake was only 15% in comparison to the dimer. There was no specific binding outside the GI tract and no binding to TFF1 or TFF3 immunoreactive cells. In conclusion, the TFF2-binding cells in the gastrointestinal tract seem to have basolateral, receptor-like activity to all three TFF peptides. The mucous neck cells of the stomach predominantly take up TFFs with two trefoil domains, indicating a different receptor-like activity in the stomach compared to the rest of the GI tract.

Human intrinsic factor expressed in the plant Arabidopsis thaliana

Intrinsic factor (IF) is the gastric protein that promotes the intestinal uptake of vitamin B12. Gastric IF from animal sources is used in diagnostic tests and in vitamin pills. However, administration of animal IF to humans becomes disadvantageous because of possible pathogenic transmission and contamination by other B12 binders. We tested the use of recombinant plants for large-scale production of pathogen-free human recombinant IF. Human IF was successfully expressed in the recombinant plant Arabidopsis thaliana. Extract from fresh plants possessed high B12-binding capacity corresponding to 70 mg IF per 1 kg wet weight. The dried plants still retained 60% of the IF activity. The purified IF preparation consisted of a 50-kDa glycosylated protein with the N-terminal sequence of mature IF. Approximately one-third of the protein was cleaved at the internal site em leader PSNP downward arrow GPGP. The key properties of the preparation obtained were identical to those of native IF: the binding curves of vitamin B12 to recombinant IF and gastric IF were the same, as were those for a B12 analogue cobinamide, which binds to IF with low affinity. The absorbance spectra of the vitamin bound to recombinant IF and gastric IF were alike, as was the interaction of recombinant and native IF with the specific receptor cubilin. The data presented show that recombinant plants have a great potential as a large-scale source of human IF for analytical and therapeutic purposes.

ErbB1 and prostate cancer: ErbB1 activity is essential for androgen-induced proliferation and protection from the apoptotic effects of LY294002

BACKGROUND

Androgens play a critical role in proliferation and survival of prostate cancer cells, but the mechanisms leading to these effects are poorly understood. ErbB receptor tyrosine kinases have been implicated in the development of prostate cancer.

METHODS

We examined the interaction between the ErbB receptors and androgens using the LNCaP androgen-sensitive prostate tumor model.

RESULTS

In the absence of androgens, the cells have low levels of ErbB1 and relatively high levels of ErbB2. Addition of androgens to the medium reversed the ratio; ErbB1 levels rose and ErbB2 levels dropped in response to treatment with the synthetic hormone, R1881. Expression of ErbB activating ligands was found to be constitutive and androgen-independent. The androgen-induced proliferation of LNCaP cells was completely inhibited by the addition of the small molecule ErbB1 tyrosine kinase inhibitors CGP59326 and the bispecific inhibitor (PKI166) for ErbB1 and ErbB2 to the culture medium. Furthermore, in the absence of androgens the relatively low proliferative level was further significantly reduced in the presence of CGP59326. Inhibition of PI3K activity by LY294002 led to induction of apoptosis in androgen-deprived LNCaP cells. Androgen-mediated rescue from LY294002-induced apoptosis was inhibited by addition of CGP59326 to the cells.

CONCLUSIONS

These results suggest a model whereby androgens promote an increase in the activity of the epidermal growth factor (EGF)-network by increasing ErbB1 levels, and this activity of is essential for androgen-induced proliferation and survival of the prostate cancer LNCaP cell line.

Diversity in rat tissue accumulation of vitamin B12 supports a distinct role for the kidney in vitamin B12 homeostasis

BACKGROUND

Vitamin B(12) in plasma is complexed to the carrier proteins transcobalamin (TC) and haptocorrin. The TC-B(12) complex is filtered in the glomeruli and reabsorbed in the renal tubules by receptor-mediated endocytosis, providing a route for a significant renal accumulation of vitamin B(12). The present study investigates the role of the rodent kidney in B(12) homeostasis by examining the distribution of vitamin B(12) in rats during vitamin B(12) depletion or B(12) load, and compares kidney accumulation with the vitamin distribution in other tissues including brain, liver, testes, intestine, spleen and plasma.

METHODS

Fifteen rats were fed on a diet containing different concentrations of B(12) supplemented with s.c. injections of B(12). Twenty four hours prior to sacrifice, all animals were injected with [(57)Co]B(12). The vitamin contents of kidneys, liver, spleen, brain, testis, intestine, skeletal muscle, serum and urine were analysed. Both total tissue vitamin B(12) accumulation and [(57)Co]B(12) were determined to compare steady-state B(12) and the distribution of an acutely injected dose. In the kidney, free and protein-bound B(12) was determined by gel filtration.

RESULTS

The rat kidneys accumulated more B(12) during normal and loaded conditions than any other tissue. A 110-fold increase in vitamin content was observed from the deficient to the loaded conditions in the kidney compared with a 3.5-fold increase in the liver. In contrast to all other organs, significantly smaller amounts of acutely injected B(12) accumulated in the kidneys in the vitamin-deprived state compared with both the normal and the vitamin-loaded condition.

CONCLUSIONS

The present study suggests a significant role for the rodent kidney in vitamin B(12) metabolism. We propose a model for rat tissue uptake consistent with the presence of two different TC-B(12) receptors and renal uptake following filtration of TC-B(12) in the glomeruli. The presented model allows for the reduced renal uptake and accumulation in vitamin-deprived conditions, thus reserving the vitamin for other tissues, including nerve tissue and bone marrow, which are more sensitive to vitamin B(12) deficiency.