Prostate cancer treatment with ultrasound-guided transperineal brachytherapy: analysis of the treatment results of our first 150 patients

This paper presents outcome data from our initial 150 patients who had received all or part of their radiation dose for the treatment of adenocarcinoma of the prostate using permanent radioactive seed implantation. Median follow-up for this group is now three years. Fifty-six patients had tumors with gleason scores of 7 or greater, and 94 had gleason scores of 6 or less. The average age was 67 (range 42 to 79). Ninety-five percent have maintained biochemical control of their disease (PSA level of 1.0 or less) since the time of implant. Questionnaires were sent to all patients to assess quality of life issues. Fifty-eight percent have maintained potency. Ninety-eight percent of those surveyed said they would recommend this treatment to other men with prostate cancer. Our results support the findings of other published series. Ultrasound-guided transperineal brachytherapy is a well-tolerated procedure with excellent cancer control rates and should be considered as a treatment option in men with localized prostate cancer.

Delta-aminolevulinic acid in superficial basal cell carcinomas and normal skin-a microdialysis and perfusion study

Delta-aminolevulinic acid (ALA) is used for photodynamic therapy of basal cell carcinoma (BCC) as it is converted to protoporphyrin IX in tumour tissue. During illumination with 635 nm light a photochemical reaction takes place, singlet oxygen is generated and the tumour destroyed. In this study we used the microdialysis technique to quantify the concentration of ALA at a certain depth in tumour and healthy skin. The penetration ability of ALA was investigated as a function of time in BCCs (n = 14) and in normal skin (n = 4) after topical application. The microdialysis catheters were inserted intracutaneously and the depth position recorded by means of ultrasound. Microdialysate sample concentrations of amino acids and ALA were determined by high performance ion-exchange chromatography. A laser Doppler perfusion imager measured perfusion in the BCCs. The data show that the average depth of the microdialysis catheters was 0.5 mm. The interstitial ALA concentration in the BCCs increased from 0 to 3.1 mmol/L 15 min after application of ALA, whereas no measurable amounts of ALA were found in healthy skin. The blood perfusion was 2.5-fold increased in the BCCs. The interstitial levels of amino acids were not significantly changed during the ALA treatment. In summary, we found that ALA rapidly penetrates tumour skin. We conclude that microdialysis seems to be well suited for pharmacodynamic studies of ALA in skin.

Typing for the human lewis blood group system by quantitative fluorescence-activated flow cytometry: large differences in antigen presentation on erythrocytes between A(1), A(2), B, O phenotypes

BACKGROUND

Lewis phenotyping by hemagglutination is an unreliable routine method for Lewis antigen designation. Now genomic typing of the Lewis gene is available. Additionally, flow cytometry has been used for typing. We wanted to compare the results of Lewis typing in healthy individuals using the three methods.

MATERIALS AND METHODS

Ninety-three randomly selected plasma donors were genotyped for inactivating Secretor (FUT2) G428A and Lewis (FUT3) T59G, T202C, C314T, G508A and T1067A point mutations. All Le(a+b-) individuals (nonsecretors) were homozygous for the FUT2 G428A mutation and all Le(a-b-) individuals had inactivating mutations on both FUT3 alleles. Fixed erythrocytes were analyzed by fluorescence-activated flow cytometry and the results were compared with hem- agglutination and genotypic data. Antigen availability was expressed as median fluorescence intensity and as percentage positive cells with fluorescence intensities > or =10(2).

RESULTS

Using an anti-Le(a) reagent a mean of 99% of erythrocytes from Le(a+b-) individuals and 1% of erythrocytes from Le(a-b-) or Le(a-b+) individuals were stained positive. Using an anti-Le(b) reagent, a mean of 71% of erythrocytes from A(1), 95% from B and 99% from O and A(2) Le(a-b+) individuals and less than 10% of erythrocytes from Le(a-b-) or Le(a+b-) individuals were stained positive. After papain treatment 100% of the erythrocytes from A(1) and A(1)B Le(a-b+) individuals stained positive without increase in background staining. The flow cytometric technique revealed large differences in staining intensities, within each ABO Le(a-b+) subgroup which was not directly correlated to plasma donation frequencies nor to Secretor or Lewis genotypes.

CONCLUSION

Flow cytometry may prove valuable as a Lewis blood group typing technique but also as a research tool when investigating Lewis phenotypes of human erythrocytes.

Codeine concentration in hair after oral administration is dependent on melanin content

BACKGROUND

Analysis of drugs in hair has been used on a qualitative basis to estimate earlier exposure to drugs. Clinical applications are rare because of the lack of dose-response relationships in the studies performed to date, and questions remain regarding the mechanisms of drug incorporation into hair. Several human studies have shown differences in drug accumulation between pigmented and nonpigmented hair. However, the melanin concentration in hair was not determined and correlated to the amount of drug incorporated.

METHODS

Nine human subjects were given codeine as a single oral dose, and plasma codeine concentrations were determined for 24 h, using gas chromatography-mass spectrometry. Hair samples were obtained weekly for a month. Total melanin, eumelanin, and codeine were measured quantitatively in hair samples by spectrophotometry, HPLC, and gas chromatography-mass spectrometry, respectively.

RESULTS

There was an exponential relationship between codeine and melanin concentrations in hair, (r(2) = 0.95 with total melanin and r(2) = 0.83 with eumelanin). After normalizing the results by the area under the curve for codeine in plasma, we obtained r(2) = 0.86 for codeine vs total melanin and r(2) = 0.90 vs eumelanin.

CONCLUSIONS

Our results stress the importance of melanin determination when measuring drugs in hair. We postulate that analysis of drug concentration in hair may be worthwhile in the monitoring of drug compliance if the results are normalized for melanin content.

Capsaicin treatment induces histamine release and perfusion changes in psoriatic skin

To determine whether neurogenic factors may be of importance in the regulation of histamine release and blood flow in psoriatic plaque, the effect of capsaicin was studied in 22 psoriatic patients with active, untreated psoriatic lesions. In each of 12 patients, one microdialysis fibre was placed in non-lesional skin and one was placed in lesional skin at depths of 0.7 and 0.9 mm, respectively. Dialysates were collected for the analysis of histamine in the resting state and after 60 min of repetitive epicutaneous application of 1% capsaicin above the microdialysis catheter. In 10 patients, topical capsaicin and placebo were applied for 24 h to lesional/lesion-free skin. Skin blood flow and perfusion (evaluated using the 133xenon clearance technique and scanning laser Doppler, respectively) were measured before the application of capsaicin and after removal. After 60 min of capsaicin treatment, both the perfusion and interstitial concentration of histamine, as well as the net release of histamine, were significantly increased in affected (from 38 +/- 6 to 45 +/- 6 nmol/L, mean +/- SEM) and unaffected (from 15 +/- 2 to 19 +/- 2 nmol/L) skin. Compared with placebo, 24 h of treatment with capsaicin caused a 15% decrease in perfusion in lesional skin. The results are compatible with the hypothesis that capsaicin-sensitive nerves may induce histamine release in non-lesional and lesional skin and that afferent unmyelinated nerve fibres may contribute to the high blood flow in psoriatic plaques.

The effect of a low molecular mass thrombin inhibitor, inogatran, and heparin on thrombin generation and fibrin turnover in patients with unstable coronary artery disease

AIM

This study evaluated a novel specific thrombin inhibitor, inogatran, in comparison with unfractionated heparin, with regard to markers for coagulation activity in patients with unstable coronary artery disease.

METHODS AND RESULTS

In the Thrombin Inhibition In Myocardial Ischaemia (TRIM) study patients were randomized to one of three different doses of inogatran or to unfractionated heparin, given intravenously over 72 h. In a subpopulation of 320 patients, markers for coagulation activity were measured at baseline, during and after the study infusion. Prothrombin fragment 1 + 2, indicating thrombin generation, decreased in the low, medium and high dose inogatran groups and in the heparin group during the first 6 h of treatment by 12%, 15%, 21% and 26%, respectively. From 6 h to 72 h after the start of infusion the levels changed by -7%, -6%, -4% and +34%, respectively. The increase in the heparin group continued after the infusion was stopped. Thrombin-antithrombin complex, also indicating thrombin generation, decreased by 0%, 2%, 18% and 22%, respectively, during the first 6 h of treatment. During the same period soluble fibrin, an intermediate in fibrin formation, increased both in the low and medium inogatran group by 9%, while a decrease by 4% and 18%, respectively, was seen in the high dose inogatran group and in the heparin group. Fibrin dissolution, as measured by fibrin D-dimer, decreased during the first 24 h of treatment by 20%, 18%, 18% and 20%, respectively. The first 24 h after discontinuation of infusion, fibrin D-dimer increased by 6%, 23%, 25% and 44%, respectively. After 72 h, at the end of infusion, patients treated with inogatran, to a larger extent than those given heparin, had suffered from death, myocardial infarction or refractory angina pectoris. After 7 days this trend was less marked.

CONCLUSION

The more pronounced decrease in thrombin generation and fibrin turnover during the first 6 h of infusion, and the later increase in thrombin generation and fibrin turnover, in the heparin group, as compared to the inogatran groups, may be related to the lower clinical event rate during infusion with heparin compared with inogatran and the recurrence of ischaemic events, early after cessation of heparin infusion.

Comparison of various D-dimer tests for the diagnosis of deep venous thrombosis

Analyses of D-dimers in plasma are frequently used as diagnostic tools for deep venous thrombosis (DVT). Enzyme-linked immunosorbent assays (ELISAs) are considered to be the method of choice for quantitative assays, but are time consuming. Therefore, we have assessed plasma levels of D-dimers in patients with clinically suspected DVT using quantitative (Asserachrom D-Di ELISA and TintElize), semiquantitative (Minutex latex, D-Di latex, NycoCard D-Dimer) and qualitative (INSTANT.I.A) assays. Phlebography was used as the gold standard to verify or exclude the suspected diagnosis. We conclude that the fast assays, INSTANT.I.A and Minutex, have essentially the same negative predictive value [91% and 89%, respectively, using a cut-off value < 0.5 mg/l fibrinogen equivalent units (FEU)] for excluding DVT as the Asserachrom D-Di ELISA and TintElize tests (92%). The D-Di Latex assay had a negative predictive value of 82% (cut-off < 0.5 mg/l FEU) and turned out to be less useful in our material. The NycoCard D-dimer assay had a negative predictive value of 100% when using the cut-off value < 0.5 mg/l FEU, but this was substantially lower when the cut-off was changed to < or = 0.5 mg/l. Thus, we conclude that several fast tests offer a simpler and more rapid way of determining plasma levels of D-dimer than conventional ELISA methods without loss of clinical usefulness in excluding DVT.

Nerve-induced histamine release is of little importance in psoriatic skin

Psoriatic plaques contain an increased number of mast cells. Both the histamine concentration and release are increased in lesional skin but the underlying mechanisms are unclear. One hypothesis is that neuropeptides transmitted from thin sensory cutaneous nerves continuously stimulate mast cell release of histamine. The aim of this study was to test this hypothesis by examining if topical anaesthesia of these nerves inhibits histamine release in psoriatic skin. The concentration of histamine was measured in microdialysates obtained from lesional and non-lesional skin before and during topical anaesthesia. Concomitantly skin blood flow was measured with scanning laser Doppler (perfusion) and/or 133Xe clearance (flow) techniques in the microdialysis area. The histamine concentrations (mean +/- SEM) were 34 +/- 4 (n = 21), 14 +/- 1.5 (n = 18) (P < 0. 001) and 2.8 +/- 1 nmol/L (n = 10) in lesional and non-lesional skin and plasma, respectively. After anaesthesia of the microdialysis areas the histamine concentration in psoriatic skin increased to 44 +/- 4 nmol/L (n = 19, P < 0.05), but remained unaltered in uninvolved skin. In anaesthetized lesional skin the perfusion decreased from 3.7 +/- 0.2 to 2.5 +/- 0.3 V and blood flow decreased from 14 +/- 5 to 9 +/- 1 mL/min per 100 g (P < 0.001, n = 10). The calculated release of dermal histamine in involved skin (198 +/- 30 pmol/min per 100 g, n = 10) remained unchanged after local anaesthesia. The results indicate that neurogenic activation of mast cells is of minor importance for continuous histamine release in psoriatic skin and that the vasodilatation in the psoriatic plaque is not mediated by histamine.

Myocardial turnover of endogenous opioids and calcitonin-gene-related peptide in the human heart and the effects of spinal cord stimulation on pacing-induced angina pectoris

Earlier studies have shown that spinal cord stimulation (SCS) has antianginal and anti-ischemic effects in severe coronary artery disease. In the present study, 14 patients were subjected to right-sided atrial catheterization and atrial pacing. The patients were paced to angina during a control session and during spinal cord stimulation. Myocardial extraction of beta-endorphin (BE) during control pacing (8 +/- 22%) changed to release at the maximum pacing rate during treatment (-21 +/- 47%, a negative value representing release). Furthermore, the results indicate local myocardial turnover of leuenkephalin, BE and calcitonin-gene-related peptide. In addition, it is implied that SCS may induce myocardial release of BE which could explain the beneficial effects in myocardial ischemia.

Point mutations and deletion responsible for the Bombay H null and the Reunion H weak blood groups

OBJECTIVE

Definition of the molecular basis of the Reunion and the Bombay red cell and salivary H-deficient phenotypes.

METHODS

Sequence and expression of FUT1 and FUT2 genes from H-deficient individuals. Family segregation analysis of the mutations responsible for the fucosyltransferase defects of H, secretor and Lewis systems.

RESULTS

The Indian red cell H null Bombay phenotype depends on a new mutation of the FUT1 gene. T725-->G changing Leu242-->Arg. Their salivary nonsecretor phenotype is secondary to a complete deletion of the FUT2 gene. The red cell H weak Reunion phenotype depends on another new mutation of FUT1, C349-->T which induces a change of His117-->Tyr. Their salivary nonsecretor phenotype is due to the known Caucasian inactivating mutation G428-->A.

CONCLUSION

Single prevalent FUT1 and FUT2 point mutations and a deletion are responsible for the Indian Bombay H null and the Reunion H weak phenotypes found on Reunion island. This is in contrast with other H-deficient phenotypes where sporadic nonprevalent inactivating mutations are the rule.

Evolution of fucosyltransferase genes in vertebrates

Cloning and expression of chimpanzee FUT3, FUT5, and FUT6 genes confirmed the hypothesis that the gene duplications at the origin of the present human cluster of genes occurred between: (i) the great mammalian radiation 80 million years ago and (ii) the separation of man and chimpanzee 10 million years ago. The phylogeny of fucosyltransferase genes was completed by the addition of the FUT8 family of alpha(1,6)fucosyltransferase genes, which are the oldest genes of the fucosyltransferase family. By analysis of data banks, a new FUT8 alternative splice expressed in human retina was identified, which allowed mapping the human FUT8 gene to 14q23. The results suggest that the fucosyltransferase genes have evolved by successive duplications, followed by translocations, and divergent evolution from a single ancestral gene.

Increased interstitial histamine concentration in the psoriatic plaque

The psoriatic plaque contains an increased number of mast cells that are thought to have an important role in the initiation and maintenance of psoriatic lesions through the release of mediators such as histamine, proteoglycans, lipid mediators, and cytokines. It is not known, however, whether the interstitial concentration of histamine (and other mediators) is truly increased in the psoriatic plaque. The aim of the present study was to examine histamine concentration and histamine release from involved and uninvolved skin of psoriatic patients. Intracutaneous microdialysis was performed in lesional and nonlesional skin of 23 psoriatic subjects. The relative recovery of histamine was assessed after calibration in situ to approximately 76% in both lesional and nonlesional skin. The interstitial histamine concentration was 32 +/- 3 nmol per liter in lesional skin and 13 +/- 1 nmol per liter in nonlesional skin (mean +/- SEM) (p < 0.001). Dermal histamine release was estimated according to the Fick principle after measurements of the arterialized venous plasma histamine concentration (3 +/- 1 nmol per liter) and blood flow and was found to be 10-fold increased in lesional compared with nonlesional skin. The results are compatible with the hypothesis that mast cells in lesional skin secrete an increased amount of histamine that may contribute to the immunostimulation and inflammation in the psoriatic plaque.

Intestinal permeability in cystic fibrosis in relation to genotype

BACKGROUND

The purpose of this study was to investigate whether the increase intestinal permeability (IP) seen in patients with cystic fibrosis (CF) is correlated with the basic defect, as revealed by the patient's genotype, and/or whether the intestinal disturbance reflects secondary abnormalities such as essential fatty acid deficiency.

METHODS

Nineteen CF patients were compared with nine age- and sex-matched healthy controls. IP was evaluated by studying urinary excretion for 5 hours after a test meal containing lactulose, L-rhamnose and xylose in water. Urine was analyzed for carbohydrates, and blood samples were taken for determination of the fatty acid pattern of serum phospholipids. The CF patients were grouped according to genotype: homozygous for delta F508, heterozygous for alpha F508, or unidentified.

RESULTS

Patients who were homozygous (n = 9) or heterzygous (n = 6) for delta F508 had significantly higher lactulose/L-rhamnose excretion ratios (mean(range) values of 0.08(0.05-0.13) and 0.09(0.03-0.13), respectively) than patients (n = 4) with unidentified genotypes [0.03(0.02-0.05); p = 0.005] or healthy controls [0.02(0.003-0.06); p = 0.002]. CF patients with EFAD (n = 6) did not differ from those with a normal pattern of serum phospholipid fatty acids, the lactulose/L-rhamnose excretion ratio being 0.08(0.02-0.13) and 0.07(0.03-0.12), respectively.

CONCLUSIONS

These data show that the IP in CF was related to patient genotype; those homozygozous or heterozygous for delta F508 having a significantly increased IP compared with patients with unidentified genotypes, who had IP values within the normal range.

CMP-NeuAc:Gal beta 1-->4GlcNAc alpha 2-->6sialyltransferase catalyzes NeuAc transfer to glycolipids

Using mammalian gene-overexpression system, in vitro catalytic activities of CMP-NeuAc:Gal beta 1-->4GlcNAc alpha 2-->6sialytransferase on glycosphinogolipid acceptors were analyzed. We transfected the mammalian expression vector containing the cDNA that was cloned from Daudi cells into COS-1 cells, and selected monoclonal transfectants in the presence of G418. Although the transfected alpha 2-->6sialytransferase can catalyze NeuAc transfer onto glycoprotein acceptors more than glycolipids based on kinetic analyses, the substantial synthesis of IV6NeuAc-nLcOse4Cer was observed and the activities were 7- to 9-times higher in the transfected cells than in the mock transfectants. In addition, the transfected COS-1 cells with alpha 2-->6sialytransferase cDNA were revealed to contain a higher amount of ganglioside that has the terminal NeuAc alpha 2-->6Gal sequence in the in situ situation than the mock transfectants. These results using transfectants, together with those using the purified enzyme protein, suggest that the alpha 2-->6sialytransferase enzyme from Daudi cells can also catalyze NeuAc transfer in alpha 2-->6 linkage onto glycosphingolipid acceptors.

Significance of individual point mutations, T202C and C314T, in the human Lewis (FUT3) gene for expression of Lewis antigens by the human alpha(1,3/1,4)-fucosyltransferase, Fuc-TIII

The Lewis alpha(1,3/1,4)-fucosyltransferase, Fuc-TIII, encoded by the FUT3 gene is responsible for the final synthesis of Lea and Leb antigens. Various point mutations have been described explaining the Lewis negative phenotype, Le(a-b-), on erythrocytes and secretions. Two of these, T202C and C314T originally described in a Swedish population, have not been found as single isolated point mutations so far. To define the relative contribution of each of these two mutations to the Lewis negative phenotype, we cloned and made chimeric FUT3 constructs separating the T202C mutation responsible for the amino acid change Trp68 --> Arg, from the C314T mutation leading to the Thr105 --> Met shift. COS-7 cells were transfected and the expression of Fuc-TIII enzyme activity and the presence of Lewis antigens were determined. There was no decrease in enzyme activity nor of immunofluorescence staining on cells transfected with the construct containing the isolated C314T mutation compared with cells transfected with a wild type FUT3 allele control. No enzyme activity nor immunoreactivity for Lewis antigens was detected in FUT3 constructs containing both mutations in combination. The T202C mutation alone decreased the enzyme activity to less than 1% of the activity of the wild type FUT3 allele. These results demonstrate, that the Trp68 --> Arg substitution in human Fuc-TIII is the capital amino acid change responsible for the appearance of the Le(a-b-) phenotype on human erythrocytes in individuals homozygous for both the T202C and C314T mutations.

Purification and characterization of blood group A-degrading isoforms of alpha-N-acetylgalactosaminidase from Ruminococcus torques strain IX-70

To cleave blood group A immunodeterminants from erythrocytes (Hoskins, L. C., Larson, G., and Naff, G. B. (1995) Transfusion 35, 813-821), we purified and characterized alpha-N-acetylgalactosaminidase (EC 3.2.1.49) activity from culture supernatants of the human fecal bacterium Ruminococcus torques strain IX-70. Three isoforms separated during hydrophobic interaction chromatography. Hydroxyapatite chromatography further resolved the most hydrophilic, isoform I, into isoforms IA and IB. The most hydrophobic, isoform III, differed from IA and IB by a more acidic pH optimum, greater heat resistance, greater sensitivity to alkylating agents, and anomalous retardation during gel filtration chromatography. Isoform IB differed from IA and III in N-terminal amino acid sequence and in sensitivity to EDTA inhibition. Each cleaved nonreducing alpha(1-->3)-N-acetylgalactosamine residues from human blood group A and AB mucin glycoproteins, Forssman hapten, and blood group A lacto series glycolipids. The apparent molecular mass of denatured isoform subunits of IA, IB, and III-PII (158, 173, and 201 kDa, respectively) bore no integer relationship to the apparent molecular mass of the native isoforms (265, 417, and 530 kDa), but the latter bore a ratio of 1.96:3.09:3.93 to the weight-average apparent molecular mass of native IA (135 kDa), suggesting that the isoforms are multimers of a 135-kDa sequence. Isoforms IA and III-PII had an identical N-terminal amino acid sequence which showed homologies to the N-terminal sequence of sialidases produced by Bacteroides fragilis SBT3182, another commensal enteric bacterium.

Structural and immunochemical identification of Le(a), Le(b), H type 1, and related glycolipids in small intestinal mucosa of a group O Le(a-b-) nonsecretor

Total nonacid glycosphingolipids were isolated from small intestine mucosal scrapings of a red cell blood group O Le(a-b-) nonsecretor cadaver. Glycolipids were extracted and fractionated into five fractions based on chromatographic and immunostaining properties. These glycolipid fractions were then analysed by thin-layer chromatography for Lewis activity with antibodies reactive to the type 1 precursor (Le(c)), H type 1 (Le(d)), Le(a) and Le(b) epitopes. Fractions were structurally characterized by mass spectrometry (EI-MS and EI-MS/MS-TOF) and proton NMR spectroscopy. EI-MS/MS-TOF allowed for the identification of trace substances in fractions containing several other glycolipid species. Consistent with the red cell phenotype, large amounts of lactotetraosylceramide (Le(c)-4) were detected. Inconsistent with the red cell phenotype, small quantities of Le(a)-5, H-5-1 and Le(b)-6 glycolipids were immunochemically and structurally identified in the small intestine of this individual. By EI-MS/MS-TOF several large glycolipids with 9 and 10 sugar residues were also identified. The extensive carbohydrate chain elongation seen in this individual with a Lewis negative nonsecretor phenotype supports the concept that Lewis and Secretor blood group fucosylation may be a mechanism to control type 1 glycoconjugate chain extension.

Molecular basis for erythrocyte Le(a+ b+) and salivary ABH partial-secretor phenotypes: expression of a FUT2 secretor allele with an A-->T mutation at nucleotide 385 correlates with reduced alpha(1,2) fucosyltransferase activity

The SewA385T mutation of the FUT2 gene was found to correlate with both the erthrocyte Le(a + b+) and/or salivary ABH partial-secretor phenotypes of Polynesians. Constructs with FUT1 and FUT2 wild type genes, and the FUT2 SewA385T, seG428A and seC571T mutated alleles, were cloned into pcDNAI, and expressed in COS-7 cells. COS-7 cells transfected with the SewA385T allele had weak, but detectable, alpha(1,2)fucosyltransferase activity, with an acceptor substrate pattern similar to the wild type FUT2 gene. Comparative kinetic studies from cell extracts with mutated SewA385T and wild type FUT2 alleles gave similar Km values, but less enzyme activity was present in cells transfected with SewA385T (Vmax 230 pmol h-1 mg-1), as compared to those transfected with FUT2 (Vmax 1030 pmol h-1 mg-1), suggesting that the mutated enzyme is more unstable. These results confirm that the molecular basis for the erythrocyte Le(a + b+), and the associated ABH salivary partial-secretor phenotype, is an amino acid change of Ile129-->Phe in the secretor alpha(1,2)fucosyltransferase.

Identification of a new plasma alpha(1,3)fucosyltransferase (FUT6) allele requires an extended genotyping strategy

Screening the FUT6 gene of 40 Swedish individuals, originally selected for genotyping of FUT3, revealed an unexpected high frequency of mutations. Four were originally typed as homozygous for the enzyme lethal mutation G739A by Taq alpha I restriction pattern, but only one lacked plasma alpha(1,3)fucosyltransferase activity. Cloning and sequencing of FUT6 from 2 of them revealed a new allele, without the G739A mutation, but with two new point mutations C738T and G977A. Segregation of this allele was confirmed in Swedish and Indonesian families. Since G739A and C738T mutations are only one nucleotide apart and induce the same modification of Taq alpha I cleavage, a new screening strategy for FUT6 was adopted. The homozygous inactivating G739A mutation was for the first time identified in Caucasian and Polynesian individuals, both lacking plasma enzyme activity. The mutation C370T was present in 25 of the 40 Swedish individuals and the inactivating mutation C945A was not found at all. These findings stress the dangers of transferring restriction enzyme genotype strategies from one population to another and of inferring phenotypes from genotypes without phenotyping and/or performing confirmatory cloning and sequencing.

A missense mutation in the FUT6 gene results in total absence of alpha3-fucosylation of human alpha1-acid glycoprotein

The major alpha3-fucosyltransferase activity in human plasma is encoded by the gene for fucosyltransferase VI (FUT6). A missense mutation (Gly-739 --> Ala) in this gene is responsible for deficiency of enzyme activity in plasma. To examine whether this fucosyltransferase is the sole enzyme responsible for the alpha3-fucosylation of serum glycoproteins in the liver, we studied the fucosylation of three glycoproteins in sera of individuals with or without inactivated FUT3 and/or FUT6 gene(s) but with a functional FUT5 gene. alpha1-Acid glycoprotein was used as the principal reporter protein for liver alpha3-fucosyltransferase activity, because of its high fucose content. In all individuals with the FUT6 missense mutation Gly-739 --> Ala in double dose, no fucosylation of alpha1-acid glycoprotein was found. This alpha1-acid glycoprotein was not intrinsically resistant to fucosylation, since it was susceptible to in vitro fucosylation using an alpha3/4-fucosyltransferase isolated from human milk. The same result was found for alpha1-antichymotrypsin and alpha1-protease inhibitor. On the other hand in all individuals with alpha3-fucosyltransferase activity in plasma, alpha3-fucosylated glycoforms of the glycoproteins studied were found. The degree of fucosylation of alpha1-acid glycoprotein was correlated with alpha3-fucosyltransferase activity (Rs = 0.82). These data indicate that the product of FUT6, but not of FUT3 or of FUT5, is responsible for the alpha3-fucosylation of glycoproteins produced in liver and suggest that this organ is a major source of alpha3-fucosyltransferase activity in plasma.

Anti-carbohydrate antibodies associated with hyperacute rejection in a vascularized mouse heart-to-rat xenotransplantation model

Specificity of immune reactions has always been sought, because it facilitates intervention with unwanted mechanisms. Specific carbohydrate antigens have been proposed to be targets of antibodies in early immune responses in pig-to-man xenografts. This work was undertaken to determine carbohydrate structure for antibody response in the experimental xenograft model mouse-to-rat. Glycolipids were prepared from nine different mouse organs and separated for carbohydrate size on thin layer plates. Sera taken from normal untreated rats showed only weak or absent IgM antibody-binding to the separated mouse glycolipids. This is in accordance with the observation that mouse heart grafts are not hyperacutely rejected by the rat. However, sera taken from mouse heart xenografted rats show clear IgG and IgM antibody binding to neutral glycolipids migrating in the five-sugar region of the thin-layer plate. These rats have previously been reported to hyperacutely reject a second xenograft. Glycolipids with this particular mobility and immunostaining properties are the dominant ones in the mouse caval vein preparation, which probably represents a rather pure vascular structure. The target antigen structure was identified, by mass spectrometry and proton nuclear magnetic resonance spectroscopy, to be the Forssman pentaglycosylceramide. A commercial monoclonal antibody directed toward the Forssman antigen bound the same biochemical structure as the antibodies derived from the mouse heart-xenografted rats. Most of the IgM activity, but very little of the IgG activity was adsorbed using the Forssman terminal disaccharide solid phase.

Homozygous expression of a missense mutation at nucleotide 385 in the FUT2 gene associates with the Le(a+b+) partial-secretor phenotype in an Indonesian family

A new point mutation was found in the coding sequence of the secretor FUT2 gene. This missense mutation with an A-->T substitution at nucleotide 385 resulted in an amino acid change of Ile129 to Phe129. This mutation showed a clear genetic trait in an Indonesian pedigree and, when appearing in a homozygous form, it was associated with the red cell Le(a+b+) and salivary partial-secretor phenotype. This result suggests that the molecular basis for the Le(a+b+) and associated partial-secretor phenotype is caused by a partially inactivating amino acid change in the alpha(1,2)fucosyltransferase coded for by this new FUT2 allele.

DNA sequencing and screening for point mutations in the human Lewis (FUT3) gene enables molecular genotyping of the human Lewis blood group system

The human Lewis gene encodes an alpha(1,3/1,4)-fucosyltransferase responsible for synthesis of the Le(a) and a Le(b) antigens. To define the molecular background for non-functional Lewis genes we have sequenced PCR-amplified DNA fragments from two Le(a-b-) individuals. One was homozygously mutated at nucleotides 202(T --> C) and 314 (C --> T), altering Trp68 to Arg and Thr105 to Met, and the other was homozygously mutated at nucleotides 59 (T --> G) and 1067 (T --> A), altering Leu20 to Arg and Ile356 to Lys. Using PCR we screened for these and additionally one other mutation at nucleotide 508 (G --> A) among 40 Caucasians. Of 15 Le(a-b-) individuals, 7 typed as le59/1067le202/314, 4 as le202/314le202/314 and 1 as le59/1067le59/1067. Of 21 Le(a-b+) and 4 Le(a+b-), 17 typed as LeLe and 7 as Lele202/314. A pedigree study of 8 Lewis-positive individuals showed that the mutations at nucleotides 202 and 314 were located on the same allele.

Opposing actions of adenosine A2a and dopamine D2 receptor activation on GABA release in the basal ganglia: evidence for an A2a/D2 receptor interaction in globus pallidus

There is increasing evidence that adenosine (ADO) and dopamine (DA) interact directly in the basal ganglia via actions at ADO A2a and DA D2 receptors, respectively. The purpose of this study was to determine 1) the extent to which these receptors modulate endogenous GABA release in discrete regions of the rat basal ganglia and 2) whether GABA release is modulated by a direct and opposing interaction between ADO A2a and DA D2 receptors. Tissue slices of striatum (STR) containing globus pallidus (GP; STR/GP) and micropunches of STR, GP, and substantia nigra pars reticulata (SNr) were studied. Radioligand binding demonstrated that ADO A1, ADO A2a, and DA D2 receptors were present in each of the tissue preparations with the exception of SNr, in which ADO A2a receptors were not detected. Stimulation of ADO A2a receptors with CGS 21680 (1-10 nM) increased electrically stimulated GABA release in STR/GP slices and GP micropunches. Consistent with the lack of A2a receptors in SNr, CGS 21680 had no effect on GABA release from this region. In contrast, stimulation of DA D2 receptors with N-0437 (1-100 nM) inhibited evoked GABA release from STR/GP slices and both GP and SNr micropunches. The D2-mediated inhibition of GABA release in GP was abolished in the presence of CGS 21680 (10 nM). These experiments demonstrate that stimulation of ADO A2a and DA D2 receptors has opposing effects on endogenous GABA release in STR and GP. These opposing actions may explain the antagonistic interactions between ADO and DA that have been observed in behavioral studies and support the hypothesis that the striatopallidal efferent system is an important anatomical substrate for the A2a/D2 receptor interaction.