The existence of atypical blood group galactosyltransferase which causes an expression of A2 character in A1B red blood cells

It is generally accepted that the blood group subtypes A1 and A2 expressions are controlled by two different blood group N-acetylgalactosaminyl-transferases, that is, A1-enzyme and A2-enzyme, respectively, and that the two types of enzymes are governed by the allelic A1 and A2 genes. The observed frequencies of blood types in Caucasians are compatible to this model. However, the subtype A2 character is far more frequently observed in AB red cells than in A red cells in some black and Oriental populations. Two black blood samples with phenotype A2B contained A1-enzyme, but not A2-enzyme, and exhibited several times higher B-enzyme activity than control AB and B blood. The kinetic properties, that is, pH-activity profile and Km for UDP-Gal, of the B-enzyme from these two A2B subjects differed from that of control B-enzyme. In these two cases, therefore, the A2 character was not caused by the subactive A2-enzyme, but because of an insufficient formation of the A-substances in red cell membranes presumably caused by the competition between the A1-enzyme and the super active atypical B-enzyme at the common H-sites. The results suggest that the B gene can be subdivided into usual B1 and atypical B2, and that not only A2B subjects but also A1B2 subjects could express A2 character in their red cells. The B2 gene may be common in certain black and Oriental populations.     

Genetic mechanism of blood group (ABO)-expression

It has generally been believed that human blood group ABO is controlled by allelic ABO genes. However, this hypothesis has not yet been experimentally proven, and other possibilities such as the non-allelic gene model and the regulatory gene model for ABO locus have also been proposed. The genetic mechanisms of many unusual blood group expressions remain unanswered. Purification of human blood group N-acetylgalactosyltransferase (A-enzyme) which synthesizes A-substance, and blood group galactosyltransferase which is responsible for synthesis of B-substance, allows us to resolve these problems from an immuno-biochemical approach. It was found that rabbit antibody against-A-enzyme completely neutralized not only A-enzyme but also B-enzyme activity. Moreover, plasma from blood type O subjects contained an enzymatically inactive but immunologically cross-reactive material (CRM). Plasma from heterozygous AO and BO subjects also contained CRM, but plasma from homozygous AA and BB subjects did not contain CRM. These facts led us to conclude that the ABO genes are allelic in the strict sense, refuting other genetic models for ABO locus. Genotypes of phenotype A and B subjects can be unequivocally determined by examining the presence or absence of CRM in their plasma. Mechanism of the unusual blood group inheritance of Cis-AB (i.e., AB and/or O childbirth from AB X O parent) was elucidated by examining properties of the A and B enzymes, CRM in their plasma, and separation of active enzymes and CRM by affinity chromatography. It became clear that Cis-AB expressions in one family was due to unequal chromosomal crossing-over producing a single chromosome with the genes for A and B enzymes. In contrast, in the other two unrelated families, the Cis-AB expression was due to a structural mutation in A or B gene producing a single abnormal enzyme which was capable of transferring both GalNAc and Gal to H-substance. Mechanism of very weak B expression in a family with A1Bm character was studied. Plasma enzyme activity and kinetic characteristics of B-enzyme from the subjects was not different from that of normal. However, the A1Bm red cells contained a large amount of unoccupied H-sites which can be galactosylated in vitro and become B active. Examination of membrane components by isoelectric focussing revealed that blood group components of the A1Bm membranes were distinctively different from that of the usual membranes. Consequently, the weak B expression is not due to direct mutation of ABO locus, but due to a secondary consequence of genetic abnormality of a membrane component (or components) associated with blood group substances.     

An unusual case of blood group ABO inheritance: O from AB X O

An unusual blood group inheritance, that is, a phenotype O child from AB X O parents, was found in a Japanese family. Since two other children from the parents are blood type B, this is not a case of Cis-AB inheritance. The mother is not blood A/B chimera, and normal levels of blood group N-acetylgalactosaminyltransferase (A-enzyme) and galactosyltransferase (B-enzyme) were detected in her plasma. Therefore, the mother is genetically true AB heterozygous. The two sons with phenotype B had normal levels of plasma B-enzyme, but had no A-enzyme, and the father and the daughter with phenotype O had neither A- nor B-enzyme in their plasma. The analyses of 24 genetic marker systems indicated that the O daughter was a true child of the parents. The affirmative probability of parentage on the O daughter was calculated to be .9999999917 by Bayes' theorem. We concluded that the genotype of the O daughter was not the usual 00, and that this rare O expression might be due to a new structural mutation or a deletion in either maternal A or B gene during oogenesis.     

Enzymes Lytic against Pseudomonas aeruginosa Produced by Bacillus subtilis YT-25

A bacterium YT–25 which produces enzymes lytic against Pseudomonas aeruginosa was isolated from soil and it was identified as Bacillus subtilis.

A₁-enzyme, A₂-enzyme, B-enzyme and NLF (Native Cell-Lytic Factor) which contribute the lysis of P. aeruginosa were purified from the culture filtrate of strain YT–25.

Purified A₁-enzyme, A₂-enzyme and B-enzyme individually lysed the vegetative cells of P. aeruginosa in the presence of NLF.

NLF is a low molecular basic peptide and seemed to alter the sufrace structure of P. aeruginosa.

B-enzyme hydrolyzed the peptidoglycan purified from P. aeruginosa to release the reducing groups, but A₁-enzyme and A₂-enzyme released neither reducing groups nor free amino groups from the peptidoglycan.     

Human-type blood groups and Gm factors in gibbons (Hylobates)

Blood specimens from 69 gibbons (63Hylobates lar, 4Hylobates concolor, and 2Hylobates pileatus) were tested for human-type ABO, MN, and Rh blood groups. AmongH. lar, three phenotypes were noted in the ABO and MN blood groups respectively, but all fourH. concolor were grouped as AM. All group A gibbons were of subgroup A₁; subgroups A₂B and A₁₂B were observed at a low frequency in group AB gibbons. Le^b antigen was detected in about 30% of the red cell samples fromH. lar, but all the samples were negative for Le^a. All the gibbons tested had c(hr) antigen but no other Rh antigens (D, C, E, and e) in their red cells. Some selected blood samples fromH. lar were also tested for some other blood group antigens and for the Gm and Inv factors. The Jk^a antigen was detected in all the red cell samples tested, but the S, s, U, K, k, and Fy^a antigens were not. In the tests of plasma with anti-Gm (1),H. lar could be divided into two groups, i.e., Gm(1)^Gi and Gm(–1)^Gi; Gm(2), Gm(4), and Inv(1) were absent in the species.     

Evaluation of the parameters of total,nutritive, and shunt blood flows in the skin microvasculature using laser Doppler flowmetry

Examination of 28 healthy subjects and 66 patients was performed using laser Doppler flowmetry (LDF) of the skin of fingers in the red and infrared ranges and wavelet analysis of microvascular blood flow oscillations. Formulas were suggested for the total (TF), nutritive (NF), and shunt (SF) local blood flows. TF = MI × A_c × A_n /(P_m × ), where MI is the microcirculation index in perfusion units (PU), A_n and A_c are the averaged maximum amplitudes of the neurogenic and cardiac rhythms (in PU), P_m is the mean arterial pressure (in mm Hg), and is the mean square deviation of the amplitude of blood flow oscillations (in PU). NF = TF/SP, where SP is the shunting parameter. SP = A_n/A_m, where A_m is the averaged maximum amplitude of the myogenic rhythm (in PU). SF = TF - NF. Significant positive relationships between the skin oxygenation and NF (red), temperature and TF (red), and blood flow measured by hydrogen clearance and TF (infrared) were revealed by comparison of the LDF parameters with polarographic and thermographic data. The advantages of the LDF parameters compared with the MI were shown, especially in skin denervation syndromes. The TF decreased in the case of complete anatomic rupture of the median nerve and increased in reflex sympathetic dystrophy, with both cases being accompanied by a deficit of the NF (red).Translated from Fiziologiya Cheloveka, Vol. 31, No. 1, 2005, pp. 114–119.Original Russian Text Copyright © 2005 by Krupatkin.     

An enzyme basis for blood type A intermediate status.

The blood type A is known to be subclassified as A1, A2, and A1-A2 intermediate (Aint), depending upon red cell agglutinability with anti-A1 and anti-H lectins. Approximately 80% of the blood group H-sites remained unglycosylated in type Aint erythrocyte membranes. Plasma from Aint individuals contains a special blood group GalNAc transferase (UDP-GalNAc:2''-fucosylgalactoside-alpha-3-N-acetylgalactosaminyl transferase), which is different from the enzyme in A1 plasma and the enzyme in A2 plasma. A1-enzyme has strong affinity to UDP-GalNAc and 2''-fucosyllactose, A2-enzyme has low affinity to both substrates, and Aint-enzyme has strong affinity to UDP-GalNAc and very low affinity to 2''-fucosyllactose, which is a soluble analog of the H-substances. The low degree of glycosylation of the blood group H-sites due to the low affinity of Aint-enzyme with the H-substances can account for the lower A activity and higher H activity in Aint red cells than in A1 red cells. The blood group A allele can be subdivided into three common alleles, A1, A2, and Aint, each controlling the formation of different types of blood group GalNAc transferases.     

The biosynthesis of blood group B determinants by the blood group A gene-specified alpha-3-N-acetyl-D-galactosaminyltransferase

The blood group $\text{A}{}^1$ gene-specified α-3-N-acetyl-D-galactosaminyl-transferase in human plasma, when concentrated by adsorption onto group O red cell ghosts or Sepharose 4B, catalyses the transfer of D-galactose in α-linkage to low-molecular-weight H-active acceptors. The product synthesised with 2′-fucosyllactose is chromatographically indistinguishable from the blood group B-active tetrasaccharide, Galα1→3[Fucα1→2]Galβ1→4Glc. The optimum pH for the transfer of D-galactose by the $\text{A}{}^1$-transferase is 7. At this pH the V_max for the transfer of N-acetyl-D-galactosamine is about 300 times higher than that for the transfer of D-galactose. These results indicate that an $\text{A}{}^1$-transferase can, under centain conditions, synthesise B determinant structures.     

Glycolipid- and glycoprotein-based blood group A antigen expression in human thrombocytes. A1/A2 difference

Total non-acid glycolipid fractions and total sodium dodecylsulphate (SDS) solubilized protein fractions were isolated from human thrombocytes obtained from single human donors having different blood group A₁/A₂ phenotypes. The blood group A glycolipid antigens were characterized by immunostaining of thin layer plates with different monoclonal anti-A antibodies. The glycoproteins carrying blood group A epitopes were identified by SDS-PAGE and Western blot analysis using a monoclonal anti-A antibody. Blood group A glycolipid antigens were found in both A₁ and A₂ thrombocytes but the A₂ individuals expressed at least ten times less A glycolipids compared to the A₁ individuals. Expression of A type 3/4 chain and small amounts of A type 1 chain glycolipids were seen in thrombocytes of both A₁ and A₂ individuals, while the type 2 chain A glycolipids appeared to be missing from the A₂ thrombocytes. Blood group A reactive glycoproteins were only found in thrombocytes of A₁ individuals and could not be detected in A₂ individuals or a blood group O individual. The major blood group A glycoprotein were found as a double band migrating in the 130 kDa region.Abbreviations SDS sodium dodecyl sulfate - PAGE polyacrylamide gel electrophoresis - HPTLC high performance thin layer chromatography - CBB Coomassie brilliant blue - GVH graft versus host Part of this work was presented at the Xth International Symposium on Glycoconjugates, Jerusalem, Israel. September, 1989.In the short hand designation for glycolipids, the letter indicate blood group determinant, the first numeral, the number of sugar residues, and the second numeral, the type of carbohydrate chain. Thus, A-6-1 means a hexaglycosylceramide with a blood group A determinant based on the type 1 carbohydrate chain.     

Serology and gene sequence analysis of rare subgroup A3 blood group

To investigate the serological phenotypic characteristics and possible mechanism of subgroup A₃, a blood donor's ABO phenotypes were detected by the conventional microcolumn gel method and classic tube method. N-acetylgalactosaminyl transferase activity was detected by the non-radioactive phosphate coupling method. ABO subtype genotyping was determined by PCR-SSP and exons 1-7 of ABO gene were analyzed by Sanger sequencing. The donor's blood type was subgroup A₃ as evaluated by serological test. There was no N-acetylgalactosaminyl transferase activity in the red blood cells and weak N-acetylgalactosaminyl transferase activity in the plasma. The ABO blood group genotyping result was ABO*AO1, and the gene sequencing result was confirmed as A221/O01. Sequencing results showed two mutations, 467C>T and 607G>A in exon 7 in ABO*A allele. In conclusion, it is suggested that the ABO blood group of the donor be subgroup A₃, which may be induced by mutations 467C>T and 607G>A, and led to a decrease in N-acetylgalactosaminyl transferase activity and resulted in weakened A antigen.     

Changes in glycine and leucine transport during red cell maturation in the rat

Both glycine and leucine transport in rat red blood cells have been studied. The glycine uptake showed two different components, one sodium-dependent and another diffusion-like process. In contrast, leucine uptake was sodium independent. Both, Na⁺-dependent glycine and the overall leucine uptake in red blood cells showed a saturable pattern. Kinetic parameters in reticulocytes were: i) glycine: apparent Km 0.16 mM; V_max 100.2 nmol/ml ICW/min; ii) leucine: apparent Km 2.11 mM; V_max 3.88 mol/ml ICW/min. The erythrocytes kinetic parameters were: i) glycine: apparent Km 0.17 mM; V_max 9.47 nmol/ml ICW/min; leucine; apparent Km 4.77 mM; V_max 7.42 mol/ml ICW/min. The Kd values (sodium independent glycine uptake) were similar in both kind of cells, but the importance of this component in total glycine uptake in erythrocytes was much higher than in reticulocytes. Our results confirm that rat red blood cells have both saturable leucine and Na⁺-dependent glycine uptake, but some important changes occur during cell maturation.     

Type A-insulin resistance with lipopexia on extremities: a case report.

We present the unusual case of a 17-year-old female with insulin-resistant diabetes, acanthosis nigricans, hirsutism, amenorrhea, dental dysplasia and lipopexia on the extremities. She had been diagnosed as having border line diabetes with hyperinsulinemia at age 12 when she was not obese and diabetes mellitus at age 13. On admission, she was obese and had lipopexia only on the extremities. The presence of hyperinsulinemia and poor response to exogenous insulin suggested severe insulin resistance. Insulin binding to transformed B-lymphoblasts derived from her was extremely low compared to the normal control, showing decreased receptor affinity. Her parents and sister exhibited hypersecretion of insulin in response to a 75 g oral glucose tolerance test. Her mother was diabetic, and her father and sister had border line diabetes, whereas her brother had a normal response. These findings support strongly the diagnosis of a type A syndrome with severe insulin resistance associated with lipopexia on the extremities. A genetic defect in the insulin receptor gene may be responsible.     

The effects of light on sex determination in gametophytes of the fern <Emphasis Type="Italic">Ceratopteris richardii</Emphasis>

The sexuality of homosporous fern gametophytes is usually determined by antheridiogen, a pheromone that promotes maleness. In this work the effect of photomorphogenically active light on antheridiogen-induced male development was examined for gametophytes of Ceratopteris richardii. Although blue light did not affect sensitivity to Ceratopteris antheridiogen (A_Ce) in wild-type gametophytes, it was found that the gametophytes of the her1 mutant, which are insensitive to A_Ce, developed into males when grown under blue light in the presence of A_Ce. Thus, we conclude that another A_Ce-signal transduction pathway activated by blue light exists latently in the gametophytes of C. richardii. Red light, on the other hand, suppressed male development. Because simultaneous red and blue light-irradiation did not promote male development in the her1 gametophytes, the action of red light seems to dominate that of blue light. The results of experiments with a photomorphogenic mutant also suggested that phytochrome may be involved in the action of red light.     

Bicarbonate permeability and immunological evidence for an anion exchanger-like protein in the red blood cells of the sea lamprey,Petromyzon marinus

Physiological and immuno-blotting experiments were used to determine whether the red blood cell membrane of a primitive vertebrate, the sea lamprey Petromyzon marinus, contained a counterpart similar to the vertebrate anion exchange protein known as AE1 or band 3. Results of the physiological experiments which measured CO₂ production after adding H¹⁴CO ₃ ^- to the extracellular saline, indicated significant transmembrane bicarbonate movement in lamprey blood which unlike that in most vertebrates, was insensitive to inhibition by 4,4 diisothiocyanatostilbene-2,2 disulfonic acid. The present study also showed that lamprey red blood cells possess acetazolamide-sensitive carbonic anhydrase which is an important component of CO₂ production by vertebrate red blood cells. Polyclonal immunoglobulins against a 12 amino acid domain in the C-terminus of the mouse AE1 recognized a trout red blood cell membrane protein with a relative molecular mass of 97 kDa, but failed to immunoreact with any membrane proteins from the red blood cells of lamprey. Antibodies against trout AE1 immunoreacted with trout red blood cell membrane proteins of approximately 97 kDa, 200 kDa and >200 kDa. Interestingly, only a 200-kDa membrane protein from the red blood cells of the primitive lamprey immunoreacted with the trout anti-AE1 immunoglobulin proteins. Therefore, lamprey red blood cells appear to possess an AE1-like protein that may be physiologically different than that in most other vertebrates.     

Improved detection of β-thalassaemia carriers by a two-test method

Summary Seven red cell parameters, taken one at a time and in their 21 possible pairs, were investigated for their power to discriminate between adult carriers of the -thalassaemia allele and adult normal subjects. The red blood cell count (RBC), haemoglobin concentration (Hb), haematocrit (Hct), mean cell volume (MCV), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC), and haemoglobin A₂(HbA₂) fraction were measured in 24 obligate heterozygotes and in 99 adult controls with comparable age and sex distributions. Quadratic discriminant functions were computed using Bayesian analysis of univariate and bivariate Gaussian density functions. Classification errors were then calculated by integrating the density function for one genotype over the region assigned to the other.In the univariate case, MCH led to the lowest cost of misclassification while MCV was the second best discriminant for all posterior probabilities considered. In the bivariate case, MCV combined with percentage Hb A₂ yielded the best discrimination and generated misclassification costs roughly 1/30 of those generated by the most efficient single parameter. When use of MCV alone cannot classify an individual reliably either as a heterozygote or as homozygous normal, combined use of MCV and percentage Hb A₂ is recommended for maximum accuracy.Application of this screening method to 260 adult subjects at risk for thalassaemia heterozygosity yielded an unbiased frequency of 0.067 for the adult carrier in the Montreal Greek community, a value similar to that reported in the source population in Greece. The improved discriminations thus achieved is particularly useful for sibs of affected subjects whose high prior probability of heterozygosity (0.67) impairs classification.     

Anticonvulsant Activity of B2, an Adenosine Analog,on Chemical Convulsant-Induced Seizures

Epilepsy is a chronic neurological disorder characterized by recurrent seizures. However, approximately one-third of epilepsy patients still suffer from uncontrolled seizures. Effective treatments for epilepsy are yet to be developed. N ⁶-(3-methoxyl-4-hydroxybenzyl) adenine riboside (B2) is a N⁶-substitued adenosine analog. Here we describe an investigation of the effects and mechanisms of B2 on chemical convulsant-induced seizures. Seizures were induced in mice by administration of 4-aminopyridine (4-AP), pentylenetetrazol (PTZ), picrotoxin, kainite acid (KA), or strychnine. B2 has a dose-related anticonvulsant effect in these chemical-induced seizure models. The protective effects of B2 include increased latency of seizure onset, decreased seizure occurrence, shorter seizure duration and reduced mortality rate. Radioligand binding and cAMP accumulation assays indicated that B2 might be a functional ligand for both adenosine A₁ and A_2A receptors. Furthermore, DPCPX, a selective A₁ receptor antagonist, but not {"type":"entrez-protein","attrs":{"text":"SCH58261","term_id":"1052882304"}}SCH58261, a selective A_2A receptor antagonist, blocked the anticonvulsant effect of B2 on PTZ-induced seizure. c-Fos is a cellular marker for neuronal activity. Immunohistochemical and western blot analyses indicated that B2 significantly reversed PTZ-induced c-Fos expression in the hippocampus. Together, these results indicate that B2 has significant anticonvulsant effects. The anticonvulsant effects of B2 may be attributed to adenosine A₁ receptor activation and reduced neuronal excitability in the hippocampus. These observations also support that the use of adenosine receptor agonist may be a promising approach for the treatment of epilepsy.     

A case of dengue hemorrhagic fever in a Japanese child

A 6-year-old Japanese girl contracted a febrile illness with hemorrhagic manifestations when she traveled in Indonesia. A remarkable decrease in the numbers of platelets and white blood cells was observed in her acute-phase blood specimens. Her father, who accompanied her, showed dengue fever-like symptoms at almost the same time as her illness. It was determined by serological tests that they were infected with dengue virus type 1. Moreover, she showed a secondary antibody response to the flavivirus due to the pre-existing antibody to Japanese encephalitis virus. This is the first confirmed case of dengue hemorrhagic fever (DHF) in Japanese people.     

The silent carrier of beta thalassemia: interaction with the typical beta thalassemic trait.

The case of a girl affected by a Colley's disease of moderate severity is reported. A brother and a sister had levels of Hb F respectively of 18% and 45%. The father showed all the hematological signs of heterozygous thalassemia. The mother, however, was normal so far as osmotic fragility, red cell morphology, and Hb A2 level are concerned. In vitro hemoglobin chains biosynthesis was performed in all the subjects. Both the parents showed an alfa/non alfa ratio typical of beta thalassemia. Therefore, the mother has to be considered a "silent" carrier of the trait. The daughters and the son have a less severe Colley disease originating by such a double heterozygosity.     

Lectins from<Emphasis Type="Italic">Griffonia simplicifolia</Emphasis> seeds

The physical-chemical and carbohydrate binding specificity ofGriffonia simplicifolia I (GS I) isolectins, one of the 4 lectins isolated fromGriffonia simplicifolia seeds, are described.Association constants for the binding of methyl α- and β-D-galactopyranoside and methyl 2-acetamido-2-deoxy-α-D-galactopyranoside to the A₄, A₂ B₂ and B₄ isolectins are reported.Precipitation reactions of theGriffonia simplicifolia isolectins with guaran and type B blood group substance are described.The hypothesis that subunit B is a precursor of subunit A, a process involving proteolytic cleavage of the B subunit, was tested by conducting structural studies on the 2 subunits. The results indicated that the A and B subunits are probably products of 2 separate but closely related, possibly contiguous genes.