Proteomics analyses of human plasma reveal triosephosphate isomerase as a potential blood marker of methotrexate resistance in rheumatoid arthritis

OBJECTIVE

The objective of this study was to assess differentially expressed blood proteins between patients with active RA and patients in remission after MTX treatment, with the aim of identifying a biomarker of MTX resistance (MTXR).

METHODS

Two populations of RA patients treated with a stable dose of s.c. MTX for at least 3 months were constituted according to the DAS28: remission (DAS28 < 2.6; n = 24) and active disease (DAS28 > 3.2; n = 32). The two groups of RA patients were homogeneous regarding their epidemiological characteristics, except for the duration of treatment, which was longer in the remission group. After collection of a blood sample, plasma protein digestion was performed, followed by untargeted proteomics analysis. Then, a targeted analysis was performed to confirm the results of the untargeted approach.

RESULTS

Untargeted proteomics analysis revealed eight plasma proteins that were differentially expressed between the two groups of patients. Among them, triosephosphate isomerase (TPI-1) and glucose-6-phosphate isomerase (GPI), which are main actors in glycolysis, were found down-regulated in the active group. This result was confirmed for TPI-1 in the targeted proteomics analysis.

CONCLUSION

A first step was achieved in the search for biomarkers of MTXR, with the identification of two actors in glycolysis (TPI-1 and GPI). The next step will be to confirm these results in a larger cohort, including samples from treatment-naive patients, to assess the predictive potential of these protein markers.

Serum Phosphoexose Isomerase in Cancer

Serum levels of phosphoexose isomerase (PHI) were determined in 138 cancer patients. The enzyme levels showed a relation to the clinical stage of the tumor, and were, on the average, higher in advanced disease. The behavior of the enzyme levels after chemotherapy and/or radiotherapy was studied in relation to the clinical response. A statistically significant reduction of PHI activity in patients with subjective and objective or only subjective response to therapy was noted. The mean values before and after chemotherapy in patients with progression of the disease were not significantly different. The authors conclude that high levels of serum PHI are, most often, associated with an advanced and/or a metastasized tumor; furthermore PHI seems to be a reliable biologic marker of the destruction of cancer tissue.

Clinical Significance of Serum Spermine in Breast Cancer

The diagnostic significance of three polyamines (putrescine, spermidine and spermine), of carcinoembryonic antigen and of phosphoglucose isomerase have been compared in sera of patients with breast cancer or benign breast disease and normal age matched controls. The results of the study indicate that the performance of spermine was more striking than that of any of the other markers. The estimation of spermine may prove to be a valuable parameter not only in detection but also in prediction of recurrence of the disease.

Phosphohexose Isomerase and Carcinoembryonic Antigen in the Sera of Patients with Primary Lung Cancer

Phosphohexose isomerase (PHI) and carcinoembryonic antigen (CEA) were measured at the time of diagnosis in 300 patients with lung cancer. Serum levels were high in 75.7% and 53.0% of patients respectively. PHI levels were higher in large cell and small cell carcinomas (p < 0.001). CEA levels were higher in adenocarcinomas (p < 0.001). Metastatic carcinomas showed higher levels on PHI and CEA than localized cases. Survival was significantly longer in patients with normal PHI (p < 0.001) and normal CEA (p < 0.005) than in cases with elevated markers. The prognostic significance of PHI persisted in the different pathological types and stages, whereas CEA only had prognostic impact in non-small cell cases. Serial PHI determinations were useful for follow-up in 82.4% of cases with initial abnormal values and in 55.4% of cases with a normal value. Serial CEA was useful in 41% of cases with initially high value but in less than 15% of those with baseline normal. We conclude that PHI has prognostic significance independently of pathology and stage, whereas CEA was a prognostic indicator only in non-small cell cases; serial PHI determinations were useful more often than CEA for follow-up.

[Significance of glucose-6-phosphate isomerase assay in early diagnosis of rheumatoid arthritis]

OBJECTIVE

To explore the titer of glucose-6-phosphate isomerase (GPI) for early diagnosis of the outpatient with rheumatoid arthritis (RA) in real life, and to analyze its relationship with disease activity.

METHODS

In the study, 1 051 patients with arthritis were collected in the group who had joints tender and swelling, and 90 cases of healthy people as a control group. ELISA method was used to detect the serum level of GPI, and according to clinical features and laboratory test, all the patients including 525 RA patients, the other patients including osteoarthritis (OA), 134 cases of seronegative spine joint disease (SpA), 104 cases of systemic lupus erythematosus (SLE), 31 cases of primary Sjogren syndrome (pSS), 24 cases of gout arthritis (GA), 22 cases of other connective tissue diseases (including polymyalgia rheumatica, dermatomyositis, systemic sclerosis, adult Still disease) and 46 cases of other diseases (including 165 cases of osteoporosis, avascular necrosis of the femoral head, traumatic osteomyelitis, bone and joint disease, juvenile rheumatoid arthritis, tumor). The diagnostic values of GPI were assessed, and the differences between the GPI positive and negative groups of the RA patients in clinical characteristics, disease activity, severity and inflammatory index analyzed.

RESULTS

The positive rate of serum GPI in the patients with RA was 55.4%, contrasting to other autoimmune diseases (14.3%) and healthy controls (7.78%)(P<0.001). Compared with the OA and SpA patients, the RA group was increased more significantly, and the difference was statistically significant (P<0.001). The diagnostic value of GPI alone for RA was 0.39 mg/L, the sensitivity was 54.2%, and specificity was 87.3%. The positive rate of GPI in RF negative patients was 36.1%; the positive rate of GPI in anti-CCP antibody negative patients was 34.2%; the positive rate of GPI in RF and anti-CCP antibody negative patients was 24.1%. The level of GPI had positive correlation (P<0.05) with ESR, RF, anti-CCP antibody and HRF-IgG.

CONCLUSION

GPI is sensitive in the patients with RA; GPI positive is important in the diagnosis of RA with anti-CCP antibody and/or RF negative patients. The titer of GPI is related with disease activity of RA.

[Significance of antibodies to the citrullinated glucose-6-phosphate isomerase peptides in rheumatoid arthritis]

OBJECTIVE

To detect the anti-citrullinated glucose-6-phosphate isomerase (GPI) 70-88 peptide antibody (anti-C-GPI(70-88) antibody), anti-citrullinated GPI 435-453 peptide antibody (anti-C-GPI(435-453) antibody), anti-GPI 70-88 peptide antibody (anti-GPI(70-88) antibody) and anti-GPI 435-453 peptide antibody(anti-GPI(435-453) antibody) in the serum of rheumatoid arthritis (RA) patients, and examine the diagnostic values of the anti-C-GPI peptide antibodies in RA.

METHODS

The anti-C-GPI(70-88) antibody, anti-C-GPI(435-453) antibody, anti-GPI(70-88) antibody and anti-GPI(435-453) antibody were detected by enzyme-linked immunosorbent assay (ELISA) in 191 RA patients, 129 other rheumatic diseases and 74 healthy controls. The clinical and laboratory data of the patients with RA were collected, and the values of anti-C-GPI peptide antibodies in the diagnosis of RA and the relationships of anti-C-GPI peptide antibodies with the clinical and laboratory parameters analyzed.

RESULTS

(1) The mean titers of the anti-C-GPI(70-88) antibody and the anti-C-GPI(435-453) antibody in the RA patients (respectively, 68.71 ± 4.20 and 51.78 ± 3.13) were significantly higher than those with other rheumatic diseases and healthy individuals (P <0.05). However, the mean titers of the anti-GPI(70-88) antibody and anti-GPI(435-453) antibody in the RA patients were similar to those with other rheumatic diseases and healthy individuals. (2) The diagnostic sensitivity and specificity of the anti-C-GPI(70-88) antibody for RA were 41.88% and 84.50% respectively; and the diagnostic sensitivity and specificity of the anti-C-GPI(435-453) antibody for RA were 46.05% and 86.05% respectively. The sensitivity of combined detection of the two anti-C-GPI peptide antibodies was 50.79%, and the specificity was 81.40%. (3) The positive rates of the anti-C-GPI(70-88) antibody and the anti-C-GPI(435-453) antibody were 35% and 45% respectively in those patients with negative anti-cyclic citrullinated peptide antibody, anti-keratin antibody, and rheumatoid factor. (4) There was no significant difference in clinical and laboratory indicators between the anti-C-GPI(70-88) antibody or anti-C-GPI(435-453) antibody positive group and negative group.

CONCLUSION

The anti-C-GPI(70-88) antibody and anti-C-GPI(435-453) antibody can be detected in the serum of RA patients, and C-GPI may be involved in the pathogenesis of RA. There is a certain diagnostic significance for the sera-negative RA.

[Value of four serum markers in the diagnosis of rheumatoid arthritis]

OBJECTIVE

To systematically evaluate the values of 4 serum markers in the diagnosis of rheumatoid arthritis (RA).

METHODS

Serum samples were obtained from 278 RA patients and 510 control subjects and the levels of rheumatoid factor (RF), anticyclic citrullinated peptide antibody (CCP), antikeratin antibody (AKA), and glucose-6-phosphate isomerase (GPI) were detected using immune turbidimetry, ELISA, indirect immunofluorescence, and ELISA, respectively. The values of these 4 serum markers and their combinations in RA diagnosis were systemically assessed.

RESULTS

In RA diagnosis using one serum marker, two markers, and three or four markers, RF, RF+CCP, RF+CCP+GPI, respectively, had the highest sensitivity; CCP, CCP+AKA, and RF+CCP+AKA+GPI, respectively, had the highest specificity; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive predictive value; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the highest negative predictive value; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive likely ratio; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the lowest negative likely ratio.

CONCLUSION

CCP, RF+CCP, and RF+CCP+GPI are the most ideal for RA diagnosis using one, two, and three or more markers, respectively. CCP is the essential marker for RA diagnosis, and a combined detection of the serum makers can significantly improve the diagnostic accuracy.

[Diagnostic value of glucose-6-phosphate isomerase in rheumatoid arthritis patients: systematic review]

In order to evaluate the diagnostic accuracy of glucose-6-phosphate isomerase in patients with rheumatoid arthritis, retrieval was performed using the data bases of Medline, Embase, Cochrane library, Cmcc and Cbmdisc (1990 to 2007). We included the articles which reported the studies of GPI measured by enzyme-linked immunosorbent assay in the diagnosis of RA patients. Then we reviewed 15 article and used RevMan Software for analysis; the heterogeneity among the articles was determined to be high (chi2 = 191.65, P < 0.00001). When we analyzed the 5 articles wherein serum was used as the standard, we noticed homogeneity (chi2 = 6.97, P = 0.14). The summary sensitivity was 25%; the summary specificity was 80%; the area under the curve was 0.6279. Our study demonstrated that GPI exhibited high specificity and low sensitivity in diagnosing RA cases. We suggest that GPI be used in conjunction with some assay or other that is characterized by high sensitivity.

Three phenotypes of glucosephosphate isomerase in sheep: improved staining recipe

Contrary to results published recently, we observe three, rather than two, phenotypes for the enzyme glucosephosphate isomerase (EC 5.3.1.9) from sheep. The phenotypic electrophoretic patterns conform to the patterns observed for this dimeric enzyme in other species. Genotype frequencies in a flock of Southdowns do not deviate significantly from those predicted under the assumption of the Hardy-Weinberg equilibrium. A remarkable observation is that the electrophoretically distinct phenotypes of GPI are largely or entirely obliterated by the addition of 1-10 mmol/l MgCl2 to the electrophoretic buffers. Modification of the usual staining recipe for GPI result in greater resolution and shorter staining times.

Glucosephosphate isomerase polymorphism in sheep

Two types of glucosephosphate isomerase (GPI) are described for the first time in sheep. Type T produced a 3-band pattern on polyacrylamide gel electrophoresis of serum samples, whereas type M produced a pattern of 5-7 bands. When 23 Scottish Halfbred ewes showing type T were mated to 3 Suffolk rams showing type M, their 32 offspring had frequencies of 0.72 and 0.28 for T and M respectively. There was no conclusive evidence that the types were controlled by codominant alleles or by simple Mendelian inheritance and neither was sex-linked. The frequency of the rarer type (M) was sufficiently high to provide conclusive evidence of true enzyme polymorphism.

Linkage studies between the halothane (Hal), phosphohexose isomerase (Phi) and the S(A-O) and H red blood cell loci of Pietrain/Hampshire and Landrace pigs

Frequency of blood group factors at the A-O and H loci were markedly altered within halothane positive (HP) and halothane negative (HN) composite synthetic Pietrain/Hampshire lines (PTH) over four generations of selection. Linkage studies on the litters from 45 double backcross and 20 mixed and intercross matings, involving the S(A-O), H, Phi and Hal loci, were made in the PTH line and halothane positive and negative selected British Landrace lines. Crossing-over frequencies of 0.05 +/- 0.04, 0.05 +/- 0.03 and 0.1 +/- 0.03 were established between Phi and Hal, H and Hal, and Phi and H respectively. An unequal crossing-over frequency between Phi and H was found when the alleles Ha and Hcd were compared. The difference in recombination frequency between the Ha and Hcd alleles amounted to 0.04 to 0.06. No cross-overs were observed between the S(A-O) and Phi, H or Hal loci in 15 families studied. The position of the S locus in relation to the other loci could not be established, but statistical evidence of association favours a haplotype sequence of Phi-Hal-S-H.

Genetical control of phosphoglucose isomerase isozymes in the Japanese quail erythrocytes

Three phenotypes of phosphoglucose isomerase (PGI) from the Japanese quail erythrocytes were observed by horizontal starch gel electrophoresis. Population and family data from one laboratory population of quail was consistent with the theory that PGI polymorphism was controlled by two codominant, autosomal alleles designated PGIF and PGIS with gene frequency values 0.25 and 0.75, respectively. The study supported the earlier view that the Japanese quail is highly polymorphic with regard to biochemical variation.

Biochemical gene markers in the gerbil Tatera brantsii from Lesotho

Several geographically separated populations of the gerbil Tatera brantsii were investigated with protein and enzyme gene markers. Genetic variation was found in the following systems: serum albumin, 6-PGD, haemoglobin, esterase, IDA and GPI. No variation was found in the SDH and LDH systems. There appeared to be only slight differences in gene frequencies between populations. No real seasonal variation in any of the frequencies could be established.

Phosphohexose isomerase polymorphism in the domestic cat

Genetic variation of the enzyme phosphohexose isomerase (PHI) has been found in the erythrocytes of Australian domestic cats by horizontal starch gel electrophoresis at pH 8.2. Three complex patterns of isoenzymes, designated F, FS and S, were obtained migrating anodally. Limited family studies and the distribution of the three main phenotypes indicated that the polymorphism in controlled by two codominant autosomal alleles, PHIF and PHIS. Gene frequencies for PHIF and PHIS have been calculated as 0.036 and 0.964 respectively. Three additional variant forms have also been observed.

Allozymic variation as an estimate of heterozygosity in Belgian pig breeds

An electrophoretic survey of 13 enzymes corresponding to 19 loci has been carried out in Belgian Landrace and Pietrain pig breeds. Four of these enzymes have been shown to exhibit electrophoretically detectable polymorphism. The average heterozygosity per locus was found to be 0.066 in the Belgian Landrace and 0.028 in the Pietrain pigs.

Development of a comprehensive red blood cell enzymopathy laboratory in Thailand: the study of normal activity in eight erythroenzymes in Thais

In order to provide a reference range for normal red blood cell enzyme activities in Thai, we analyzed data from 113 healthy non-anemic Thai people (55 males and 58 females) age 1-42 years, who all had a normal pattern of hemoglobin typing (HbA and HbA2 less than 3.5%). Hematological analysis was performed using an automated cell counter and the hemoglobin studies were carried out by low pressure liquid chromatography. Owing to a high frequency of alpha-thalassemia in Thailand, cases with an MCV < 75 fl were excluded from the study since these cases were likely to be heterozygotes for alpha0-thalassemia. Cases with reticulocytes > 2.5% were excluded from the study since reticulocytes have a higher enzyme activity than mature erythrocytes. Cases with abnormal red blood cell morphology, such as spherocytes and ovalocytes, were also excluded. These criteria were applied to select "normal" controls for our analysis. We assayed eight red blood cell enzyme activities in normal subjects: glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), pyruvate kinase (PK), hexokinase (HK), glucose phosphate isomerase (GPI), phosphofructokinase (PFK), aldolase (ALD) and phosphoglycerate kinase (PGK). The mean normal ranges (+/- SD) for G6PD, 6PGD, PK, HK, GPI, PFK, ALD and PGK were 12.7 (+/-2.2), 10.7 (+/-1.3), 18.5 (+/-4.0), 1.5 (+/-0.4), 80.5 (+/-11.8), 11.8 (+/-2.1), 4.5 (+/-1.6) and 370 (+/-43) IU/gHb, respectively. Age-dependent differences for the reference values for these enzyme activities were summarized. All red blood cell enzyme activities were highest during the early childhood period and slightly lower in the adult period. These values will be of clinically useful for future reference.

Patients with inflammatory arthritic diseases harbor elevated serum and synovial fluid levels of free and immune-complexed glucose-6-phosphate isomerase (G6PI)

In K/BxN mice, anti-glucose-6-phosphate isomerase (G6PI) IgG antibodies (Abs) cause joint-specific inflammation and destruction. Anti-G6PI Abs are also present in humans with inflammatory arthritis, especially among patients with rheumatoid arthritis (RA). A contributing factor to the induction of such autoantibodies may be upregulated expression of the corresponding antigen G6PI in affected tissues and/or increased levels of G6PI in the circulation. To determine G6PI levels and the presence of free G6PI and/or G6PI-containing immune complexes in sera and synovial fluids (SF) of patients with different arthritides, serum and SF obtained concomitantly from 91 clinically well-defined arthritis patients were assessed in a blinded manner for G6PI enzymatic assay and for G6PI protein concentration by ELISA. Sera and SF from patients with immune-based inflammatory arthritis contained significantly higher levels of G6PI enzymatic activity compared to sera or SF from patients with non-immune-based inflammatory arthritis or healthy controls. In addition, significantly higher levels of total G6PI protein concentration (including both enzymatically active and inactive forms) were present in sera of RA patients vs. those with other immune-based or non-immune-based inflammatory arthritis.G6PI in sera and SF were present both as G6PI-containing immune complexes and as free G6PI, with the majority of free G6PI existing as tetramers with lesser amounts of dimers and monomers. Levels of G6PI enzymatic activity in the sera of most immune-based inflammatory arthritis patients are elevated and may reflect ongoing inflammation and cell destruction. The high serum levels of enzymatically inactive forms of G6PI in RA relative to those in other arthritic diseases are partially due to G6PI-containing immune complexes, a portion of which also contains C1q. Overall, our study supports the notion that elevated G6PI levels present in patients with immune-based inflammatory arthritis may contribute to elevated levels of anti-G6PI Abs and G6PI/anti-G6PI immune complexes. This, in turn, may trigger production of proinflammatory cytokines and perpetuate the inflammatory process.

Potential endocrine function of the glycolytic enzyme glucose-6-phosphate isomerase during implantation

Glucose-6-phosphate isomerase (GPI) is a glycolytic enzyme that also acts as autocrine motility factor, a secreted protein that stimulates tumor cell motility. We have shown that GPI is required for embryo implantation in the domestic ferret. Here, we tested the hypothesis that GPI is produced and secreted into the bloodstream by ferret luteal cells. Plasma GPI activity increased significantly during the pre-implantation period in both pregnant and pseudopregnant ferrets. Explants from Corpus luteum (CL) and follicles of the pre-implantation period were cultured to ascertain their ability to secrete GPI. The medium of cultured luteal extracts contained significantly more GPI activity than the medium of cultured follicles, a control tissue. GPI activity in the medium increased significantly with increasing pregnancy stage, from pregnancy days 3 to 12. However, GPI activity within explant homogenates was the same in CL and follicles and at all days of pregnancy. Thus, CL but not follicles, secrete GPI during the pre-implantation period. Our findings suggest that GPI may be acting in an endocrine manner, being secreted from the CL into the blood, and acting to promote implantation, which occurs at a distant site, the uterus.

Glucose-6-phosphate isomerase deficiency

Most of the metabolic needs of erythrocytes are covered by glycolysis, the oxidative pentose phosphate pathway and the glutathione cycle. Hereditary enzyme deficiencies of all these pathways have been identified, among which glucose-6-phosphate isomerase (GPI) deficiency is the second most frequent erythroenzymopathy in glycolysis, being associated with non-spherocytic haemolytic anaemia of variable severity. This autosomal recessive genetic disorder may be associated in some cases with neurological impairment. GPI is a dimeric enzyme that catalyses the reversible interconversion of fructose-6-phosphate and glucose-6-phosphate. Virtually all the mutant gene products reported are characterized by marked instability and normal substrate affinities, but altered catalytic activity and electrophoretic migration rates. At the nucleotide level, 29 mutations have been reported. This chapter reviews (a) the clinical pattern of the condition; (b) biochemical and molecular studies; (c) structure-function relationships; (d) the molecular basis of neurological dysfunctions sometimes associated with GPI deficiency; and (e) the correlation between the severity of the anaemia and the molecular defect.

Erythrocyte enzyme activities in cord blood of extremely low-birth-weight infants

To investigate the features of erythrocyte metabolism in extremely immature infants, we assayed 21 enzyme activities and glutathione level in cord erythrocytes from 28 extremely low-birth-weight infants (ELBWI; defined as birth weight <1,000 g). The results were compared with those from normal adults and non-neonatal reticulocyte-rich controls. Statistical analysis revealed that activities of six enzymes (glucosephosphate isomerase, phosphoglycerate kinase, monophosphoglycerate mutase, enolase, glucose-6-phosphate dehydrogenase (G6PD), and glutathione reductase) were significantly higher, and those of eight other enzymes (phosphofructokinase, 6-phosphogluconate dehydrogenase (6PGD), glutathione peroxidase, adenylate kinase, adenosine deaminase, acetylcholinesterase, NADH methemoglobin reductase, and catalase) were lower in ELBWI taking their marked reticulocytosis into consideration. The 6PGD/G6PD ratio, which is consistently unchanged under various physiological and pathological conditions, was markedly reduced in ELBWI. Our results support the previous reports that neonatal erythrocytes have a unique metabolic pattern which is different from that of adult erythrocytes, and also suggest that the 6PGD/G6PD ratio might be an index for the developmental immaturity of fetal erythrocytes. This is the first report describing the pattern of erythrocyte enzyme activities in ELBWI.

[The effect of intravenous glucose load on levels of glucose and fructose and activity of glucose-6-phosphate isomerase in serum of patients with subarachnoid hemorrhage]

The purpose of the study was to evaluate the effect of glucose load on changes of glucose and fructose concentrations in the blood and phosphohexose isomerase activity (PHI) in the serum of patients with subarachnoid haemorrhage. The investigation was applied to 20 patients with subarachnoid haemorrhage. The control group included 20 individuals. In patients with subarachnoid haemorrhage the intravenous load of hypertonic glucose solution resulted in the extended blood hyperglycaemia and the decrease of fructose concentration in final moments of test in the III, VII and XIV day of illness. The activity of phosphohexose isomerase remained normal both before and after the glucose load.

Evaluation of phosphohexose isomerase as a metastasis marker in breast cancer patients

In this study the value of PHI serum measurements in breast cancer as an index of metastases was investigated. Serum CA 15-3 and CEA tumor marker and gamma-glutamyltranspeptidase (gamma-GT) levels were also determined in groups of patients with established distant metastases or in patients on follow-up with no evidence of disease. Fifty-one female breast cancer patients were included in the study. The mean values for each parameter were higher when metastases were present. However, the difference was mostly not meaningful. The only significant difference was observed for CA 15-3. Our data do not support the usefulness of the PHI assay for early detection of the metastases in breast cancer.

The differentiation and maturation mediator for human myeloid leukemia cells shares homology with neuroleukin or phosphoglucose isomerase

The identity of the maturation inducer capable of mediating the differentiation of human myeloid leukemic HL-60 calls to terminal monocytic cells was investigated. One of such inducers from T cells was purified as a 54.3-kD peptide. The amino acid sequence of a tryptic peptide and the enzyme cleavage sites revealed 100% homology to neuroleukin or phosphoglucose isomerase (PGI). Neuroleukin mediates differentiation of neurons and is homologous to PGI, which catalyzes the interconversion of glucose-6-phosphate and fructose-6-phosphate. The 54.3-kD inducer was shown to have PGI enzymatic activity. Separately purified PGI by substrate-elution exhibited identical specificity as the maturation inducer for HL-60 cell differentiation. They mediated a reduction of proliferating S and G2M cells, and the mature monocytic calls acquired complement receptors, phagocytic capacity, and adherence morphology. The magnitude of differentiation was dosage dependent on the inducer, with a bell-shaped curve. At the excess dose range cells did not undergo differentiation and remained in a proliferating cycle. Abnormally elevated PGI enzyme activities were detected in the plasma of acute myelogenous leukemia patients. Whether they represent an excess of the differentiation regulator in patients and are important in leukemogenesis remain to be investigated.

The appearance of Thy-1- donor T cells in the peripheral circulation 3-6 weeks after bone marrow transplantation suggests an extrathymic origin

Donor and host T cells were distinguished by T cell antigen marker Thy-1 isotype and cytoplasmic isozyme Gpi-1 in this study of bone marrow transplantation between congenic mice. During the first 3-6 weeks after irradiation and marrow transfer, percentages of cells bearing the donor Thy-1 isotype in the periphery are much lower than percentages of T cells bearing the donor Gpi-1 marker. Apparently a population of Thy-1- donor T cells exists for several weeks after bone marrow transplantation. Further study showed that this population of CD3+, Thy-1- donor T cells expressed CD4+ or CD8+ and was found in peripheral blood and spleen but not in the thymus. This finding suggests their extrathymic origin.

[Effect of intravenous glucose load on blood glucose and fructose level and glucose-6-phosphate isomerase activity in serum of patients with acute cerebrovascular disease in its earliest phase]

The purpose of the study was to investigate the dynamics of glucose and fructose concentrations in the blood changes and phosphohexose isomerase activity (PHI) in serum of unfed or after intravenous glucose injection patients, with acute cerebrovascular disease in the earliest period of illness. The investigation was done in 15 patients with transient ischaemic attacks, 30 patients with cerebral ischaemic stroke and 15 patients with cerebral haemorrhage. In patients with different forms of acute cerebrovascular damage it was found that there was hyperglycaemia in the blood of unfed patients, elevated blood fructose level and increased serum PHI activity; those changes were increased by intravenous glucose administration. The changes were most expressed in the group of patients with cerebral haemorrhage and cerebral ischaemic stroke.

Glucose phosphate isomerase (GPI) "Morcone": a new variant from Italy

Here we report the 4th Italian case of glucose phosphate isomerase (GPI) deficiency. The propositus is a young man suffering from chronic haemolytic anaemia since birth with occasional transfusion requirement. Biochemical characterization of the defective enzyme revealed increased affinity for F-6-P, decreased affinity for G-6-P and marked thermoinstability. Electrophoretic mobility appeared normal. GPI from both parents showed similar but less pronounced biochemical alterations. The variant described here seems to be different from those previously reported. Thus, we propose the provisional name of GPI "Morcone".

Combined use of serum enzyme levels as tumor markers in cervical carcinoma patients

Enzymology has acquired a prominent place in human pathology, and serum enzyme investigations have become a prerequisite for various diseases, including cancer. Serum phosphohexose isomerase (PHI), aldolase (ALD) and alkaline phosphatase (ALP) levels were evaluated in 90 untreated patients with cervical carcinoma and 84 healthy age-matched females (controls). The concentrations of the three enzymes were significantly raised (p < 0.001) in patients compared to the controls. Receiver operating characteristic curve analysis revealed higher sensitivities of PHI and ALP, as compared to ALD at different specificity levels between 60 and 95%. Combined use of PHI and ALP revealed increased sensitivity and specificity. Combined use of PHI, ALD and ALP revealed a greater number of responders with enzyme values within the normal range than nonresponders. The results suggest that combined evaluation of the enzymes might be helpful to establish a useful aid to strengthen the armamentarium currently employed in the diagnosis and treatment monitoring of patients with cervical carcinoma.

GPI Mount Scopus--a variant of glucosephosphate isomerase deficiency

Glucosephosphate isomerase (GPI) deficiency is an unusual cause of hereditary nonspherocytic hemolytic anemia. The disease, inherited as an autosomal recessive disorder, is most often manifested by symptoms and signs of chronic hemolysis, ameliorated by splenectomy. We recently diagnosed GPI deficiency in a 23-year-old Ashkenazi Jewish man who displayed the typical clinical course of this disorder. The biophysical characteristics of the GPI variant are slow electrophoretic mobility, presence of only one of the two bands normally present, and extreme thermolability. To the best of our knowledge, this is the first report of GPI deficiency in a patient of Jewish descent, and we propose to designate this enzyme variant "GPI Mount Scopus".

Enzyme-to-enzyme tunnelling between phosphoglucoisomerase and phosphofructokinase

1. Cross-linked and permeabilized rat erythrocytes were incubated for 2-5 min at 37 degrees C in the presence of ATP and either D-[U-14C]glucose 6-phosphate (3 mM) mixed with unlabelled D-fructose 6-phosphate (1 mM) or D-[U-14C]fructose 6-phosphate (1 mM) mixed with unlabelled D-glucose 6-phosphate (3 mM). 2. The contribution of molecules derived from the radioactive ketohexose ester relative to the total amount of newly formed D-fructose 1,6-bisphosphate was lower than the time-related average value for such a relative contribution in the pool of D-fructose 6-phosphate. 3. From such a difference, it was calculated that, under the present experimental conditions, 13.1 +/- 2.0% of the molecules of D-fructose 1,6-bisphosphate formed during incubation are directly derived from D-glucose 6-phosphate by a process of enzyme-to-enzyme channelling between phosphoglucoisomerase and phosphofructokinase, rather than originating from the free pool of D-fructose 6-phosphate. 4. A comparable value of 13.2 +/- 3.2% was reached when the process of enzyme-to-enzyme tunnelling was judged from the 3H/14C ratio in D-fructose 1,6-bisphosphate formed by permeabilized erythrocytes exposed for 5-15 min to D-glucose 6-phosphate (3 or 5 mM) mixed with tracer amounts of both D-[1-14C]glucose 6-phosphate and D-[2-3H]glucose 6-phosphate.

[An analysis of chimeric mice obtained by the injection of the inner cell mass into the blastocyst]

Mouse chimeras were produced using injections of ICM cells into blastocysts. Chimerism of resulting animals was determined by their coat color and spectrum of glucosephosphate isomerase isoenzymes. The use of modifications of the injection method for solving different genetic and embryological problems is discussed.

Some serum enzymes in burns and their probable correlation with surgical shock--a prospective combined surgicobiochemical study

Serum enzymes such as phosphohexoisomerase, aldolase and amylase were estimated in serum of 100 patients with thermal burn of different degrees. These enzymes were estimated at the time of admission, at 12th hour, 24th hour, 36th hour, 72nd hour, 7th day and 14th day. The patients with high serum levels of these enzymes till 72nd hour showed grave prognosis and serial measurements of these enzymes might help in predicting the outcome.

Polymorphism of erythrocyte glucosephosphate isomerase in sheep

An electrophoretic analysis of glucosephosphate isomerase (GPI) in seven Italian sheep populations suggests that this locus is more polymorphic than previously supposed. The observed phenotype distributions are in agreement with the hypothesis of the existence of three codominant alleles, GPI*F, GPI*S and GPI*N, GPI*S being the most frequent (0.935 divided by 1.000).

Glucose-6-phosphate isomerase deficiency associated with nonspherocytic hemolytic anemia in the mouse: an animal model for the human disease

The first two mutations causing hereditary glucose-6-phosphate isomerase (GPI) deficiency associated with chronic nonspherocytic hemolytic anemia in nonhuman mammals are described in the mouse. As in humans, the hemolytic syndrome, which is characterized by a diminished erythrocyte number, lower hematocrit, lower hemoglobin, higher number of reticulocytes and plasma bilirubin concentration, as well as increased liver- and spleen-somatic indices, was exclusively manifested in homozygous mutants. In comparison with wild type, heterozygous individuals exhibited neither hematologic differences nor alterations of other physiologic parameters, including plasma concentration of glucose, pyruvate and lactate, body weight, organo-somatic indices of liver, lung, kidney, spleen, and heart, as well as viability. Glycolytic intermediates, adenine nucleotides, and metabolic rate were not significantly altered in erythrocytes from heterozygotes. On the contrary, if allowance is made for the young erythrocyte population, homozygous mutant erythrocytes showed an increased concentration of glucose-6-phosphate and normal or decreased concentrations of glycolytic metabolites following the enzymatic block. The concentration of adenosine triphosphate and the glycolytic rate also appeared to be reduced. Homozygous anemic mice showed hepatosplenomegaly and typical adaptations to hypoxia, such as an elevated heart-somatic index and, for one mutant line, an enhanced lung-somatic index. Further, these animals were characterized by a marked reduction of body weight and an increase of lethality both correlated with the degree of enzyme deficiency in tissues. The latter findings were attributed to a reduced glycolytic capability of the whole organism caused by the enzyme defect in tissues, rather than representing secondary consequences of GPI deficiency in erythrocytes. The similarity in physicochemical and kinetic properties of the mutant murine proteins reported earlier with those of allozymes found in human GPI deficiency, as well as the comparable metabolic and physiologic consequences of this enzyme defect in mice and humans support that these murine mutants are excellent animal models for the human disease.

Dissociated effects of 2-deoxy-D-glucose on D-[2-3H]glucose and D-[5-3H]glucose conversion into 3HOH in rat erythrocytes

When rat erythrocytes were preincubated with 2-deoxy-D-glucose, the generation of both 3H-labelled acidic metabolites and 3HOH from D-[5-3H]glucose, the total production of L-lactate, and the generation of 14CO2, 14C-labelled acidic metabolites and 14C-labelled lactate from D-[1-14C]glucose or D-[U-14C]glucose were all lower than in erythrocytes preincubated in the absence of a hexose or in the presence of 3-O-methyl-D-glucose. However, preincubation with 2-deoxy-D-glucose failed to decrease the generation of 3H-labelled acidic metabolites and L-[3-3H]lactate from D-[2-3H]glucose, while decreasing the production of 3HOH more severely from D-[2-3H]glucose than from D-[5-3H]glucose. This may be attributable not solely to inhibition of D-glucose phosphorylation by 2-deoxy-D-glucose and 2-deoxy-D-glucose 6-phosphate, but also to inhibition by 2-deoxy-D-glucose 6-phosphate of hexose 6-phosphate interconversion in the reaction catalysed by phosphoglucoisomerase, as also observed with the purified enzyme. The generation of 3HOH from D-[2-3H]glucose should therefore be considered as a tool to assess the efficiency of interconversion of hexose 6-phosphates in the reaction catalysed by phosphoglucoisomerase, rather than to estimate D-glucose phosphorylation rate.

Evaluation of Ehrlich's test as screening test for cancer

Ehrlich's test, serum mucoproproteins, phosphohexoisomerase (PHI), and lactate dehydrogenase (LDH) levels were studied in patients with cancer and age matched controls. All parameters studied were found to be significantly increased in cancer. Evaluation of Ehrlich's test, PHI and LDH for their validity as screening tests revealed that Ehrlich's test is better suited as a screening test for cancer. A positive correlation observed in the study between serum mucoproteins and Ehrlich's test strengthens the postulation that mucoproteins are responsible for the colour development in Ehrlich's test.

Changes of enzyme activity levels in red blood cells in hemodialysis patients by recombinant human erythropoietin

In a phase II clinical trial to test the ability of recombinant human erythropoietin (r-HuEPO) to reverse the anemia of patients undergoing hemodialysis, the changes of enzyme activity in red blood cells were evaluated in 5 hemodialysis anemic patients who were treated with r-HuEPO. Concerning the activity levels measured, the following conclusions are drawn. 1) HK, ALD, TPI, G6PD and 6PGD were statistically significantly increased at the time when the hematocrit has risen by 8% with the use of r-HuEPO. 2) The enzyme activity levels of PFK, GA3PD, MPGM, ENOL, PK, GR and ADA were higher than normal already before the r-HuEPO treatment. 3) The increases of HK and G6PD by r-HuEPO, as age dependent enzymes, may reflect the generation of young red blood cells. 4) In view of the fact that they are related to ATP production in the glycolysis cycle, we infer that increases of red blood cell enzymes by r-HuEPO may play at least some part in bringing a sensation of "well-being" to severely anemic patients undergoing hemodialysis.

Rhythms of enzymatic activity in maternal and umbilical cord blood

The 24-h activity patterns of various enzymes were determined in human serum, red blood cells and white blood cells of maternal and umbilical cord blood. Blood was drawn from the brachial vein of mothers and from the umbilical cord within ten minutes after delivery. Corresponding blood specimens were obtained from 83 spontaneous labors, occurring at different hours over a period of 60 days. For each variable (variable = activity of a specific enzyme in one of the blood components) the results were grouped according to delivery hour, forming a 24-h pattern which was analyzed to elucidate time dependency. Five out of six corresponding maternal and fetal variables were similar with regard to pattern and peak time. The activity rhythms of glyceraldehyde-3-phosphate dehydrogenase and glucose phosphate isomerase in red blood cells of mothers and fetuses possessed a significant bimodal pattern. The activity rhythms of the latter enzyme in white blood cells and sera exhibited a significant 24-h period. Hexosaminidase activity exhibited a distinct 24-h rhythm in maternal white blood cells, but no significant rhythm could be detected in the fetal white blood cells. The activity of hexosaminidase showed, identical 24-h patterns in maternal and cord serum when analyzed by best fit cosine, and no significant time-dependency when analyzed by ANOVA.

A glucosephosphate isomerase (GPI) null mutation in Mus musculus: evidence that anaerobic glycolysis is the predominant energy delivering pathway in early post-implantation embryos

1. A heterozygous mouse mutant exhibiting approximately 50% of wild-type glucose-6-phosphate isomerase (GPI) activity in blood was recovered in mutagenicity experiments after combined treatment of spermatogonia with triethylenemelamine and irradiation. 2. Biochemical and immunological studies revealed no differences in physicochemical, kinetic and immunological properties between the erythrocytic enzyme of heterozygous and wild-type animals. This suggests that the mutation generates a null allele at the Gpi-1s structural locus, producing neither enzyme activity nor immunologically detectable material. 3. In accordance with the presence of only one functional Gpi-1s gene per haploid genome in the mouse, the 50% deficiency in heterozygotes is expressed in plasma and all tissues studied. 4. The genetic and physiological analyses provided no indications for further altered traits in heterozygous animals including fertility, viability and several other traits. 5. Homozygous mutants died at an early post-implantation stage of embryogenesis. 6. These findings support the hypothesis that a mutation resulting in a total loss of catalytic activity of a glycolytic enzyme leads to lethality of homozygous carriers at an early post-implantation stage of embryonic development due to a block of glycolysis and the resulting inability to utilize glucose as a source of metabolic energy. Furthermore, they indicate that anaerobic glycolysis primarily supplies the metabolic energy used by early post-implantation mouse embryos.

[Detection of early tumor reactions in irradiation of tumors of the gastrointestinal tract by measuring the onco-radiogenic enzyme peak of glucosephosphate isomerase]

In 43 patients with oesophageal, pancreatic and rectal carcinoma blood samples were taken after the first irradiation and the activity of the glycolytic enzyme glucose-6-phosphate isomerase was measured. In all patients GPI peaks occurred at reproducible time intervals. The height of the enzyme peak occurring 15.5 to 19.5 hours p.irr. was significantly dependent on tumour size and irradiation dose. The frequency of a late occurring enzyme peak was dependent on the presence of regional lymph node metastases. Possible sources of the enzyme peaks are discussed from a radiobiological point of view and the meaning of such enzyme peaks for the optimization of radiation therapy is pointed out.

[Possibilities for optimizing radiotherapy of cancers of the ENT area by measuring oncoradiogenic enzyme peaks of glucose-6-phosphate isomerase]

Blood samples were taken from 39 patients with head and neck carcinomas after the initial irradiation, and the activity of the glycolytic enzyme glucose-6-phosphate isomerase (GPI) was measured. All patients showed GPI peaks at reproducible times. The height of the enzyme peak occurring 15.5-19.5 h after irradiation, was significantly correlated with tumour size and histological tumour differentiation. A late enzyme peak was associated with regional lymph node metastases. Possible sources of the enzyme peaks are discussed from a radiobiological point of view, and the value of such enzyme peaks for the optimization of radiation therapy is pointed out.

Serum phosphohexose isomerase activities in patients with colorectal cancer

Pretreatment levels of phosphohexose isomerase (PHI) were above the cutoff limit of 107 IU/l in 41% of patients with benign intestinal diseases and in 46% of patients with colorectal cancer. Sensitivity of PHI was related to the presence of distant metastasis and the location of the primary tumor. Patients with rectal tumors presented a lower sensitivity than patients with colonic tumors. Pretreatment levels of PHI had prognostic value and patients with elevated levels of this enzyme showed a shorter disease-free interval in comparison with those patients with normal PHI activities. However, the prognostic significance of PHI was not independent of Dukes' classification. The present study indicates that PHI is not useful in the follow-up of patients with colorectal cancer after curative surgery because of its low sensitivity in the diagnosis of recurrences (47%) and its low specificity in patients without evidence of disease (76%).

Effects of mixed chimeric bone marrow repopulation on platelet storage pool-associated bleeding defects in mouse mutants

We have previously shown mouse platelet storage pool deficiency (SPD) to be associated with lesions at eight different genetic loci, each of which is sufficient to produce murine SPD. We have also shown that normal bleeding times and normal platelet functions are restored when mice with SPD are transplanted with marrow from normal mice. Conversely, when normal mice are transplanted with mutant marrow, they present symptoms of SPD. In order to determine the amount of normal platelets needed to prevent the prolonged bleeding times associated with SPD, we established stable mixed chimeric mice by transplanting various ratios of normal and mutant marrow into lethally irradiated host animals. The proportion of normal input marrow correlated well with the proportion of normal peripheral red blood cells and platelets determined in chimerae 100 days after transplantation using direct morphology and electrophoretic variants of glucose phosphate isomerase to identify normal and mutant cell populations. The proportions of normal input marrow were also reflected in the proportions of platelets with normal and mutant platelet morphology in the chimerae. This confirms that the platelet abnormality in SPD is intrinsic to the stem cell population from which the platelets are derived. When bleeding times were determined in the mixed chimeric mice, a surprisingly high percentage of normal platelets (greater than 50% and sometimes greater than 75%) were needed to stop bleeding. These results suggest that the mutant platelets in the mixed chimeric mice may interfere with normal platelet aggregation patterns. They also raise some important considerations in devising treatment for SPD. Bleeding episodes in human SPD are normally treated by platelet transfusion. The results suggest that, at least in some cases, transfusions may not be effective. Also, in future gene therapy of this disease, it is like that a functional gene will have to be present in greater than 50% of stem cells for therapy to be effective.

Glucose phosphate isomerase enzyme-activity mutants in Mus musculus: genetical and biochemical characterization

Two glucose-6-phosphate isomerase (GPI) mutants with approximately 60% residual activity in blood compared to wild type have been independently detected in offspring derived from 1-ethyl-1-nitrosourea-treated male mice. Homozygous mutants with about 20% residual activity were recovered in progeny of inter se matings of heterozygotes. However, in both mutant lines the number of homozygous mutants was less than expected suggesting an increased lethality of these animals. Results of linkage studies and of investigations of physiochemical properties of the mutant enzymes indicate point mutations at the Gpi-ls structural locus on chromosome 7. Based on these findings the two new alleles were designated Gpi-1sb-m1Neu and Gpi-1sb-m2Neu, respectively. The b-m1Neu allele codes for an erythrocyte enzyme which, in the homodimeric form, exhibits a decreased stability toward heat and urea, an altered isoelectric point, normal pH dependence, an increased Km for fructose-6-phosphate, and increased Ki's for 6-phosphogluconate and 2,3-diphosphoglycerate (2,3-DPG) compared to the wild-type enzyme. The GPI-1sb-m2Neu homodimer, in contrast, is characterized by an even stronger instability, slightly altered pH dependence, an increased Ki for 2,3-DPG, normal other kinetics, and normal isoelectric point. The different degree of stability of the mutant homodimers in vitro seems to be reflected in a different degree of stability in vivo, since GPI deficiency in general is more strongly expressed in the tissues of the homozygous Gpi-1sb-m2Neu mutant compared to the homozygous Gpi-1sb-m1Neu mutant. The similarity of the mutant enzymes to the allozymes found in human GPI deficiencies indicates the GPI deficient mouse mutants to be excellent models for the human disease.

Combination of congenital nonspherocytic haemolytic anaemia and impairment of granulocyte function in severe glucosephosphate isomerase deficiency. A new variant enzyme designated GPI Calden

In two siblings, children of non-consanguineous parents, glucosephosphate isomerase (GPI) deficiency was found to be the cause of recurrent haemolytic crises. Characterization of the variant enzyme found in both individuals revealed low specific activity in erythrocytes and leucocytes, increased electrophoretic mobility and pronounced thermolability. Evaluation of the electrophoretic data allows the conclusions that these siblings are compound heterozygous carriers of GPI deficiency. The new variant was designated GPI Calden. Further investigations revealed that isolated granulocytes of both siblings show marked reduction of bactericidal activity and decreased production of superoxide anion. With rare exceptions, deficiency of this enzyme was supposed to cause congenital nonspherocytic haemolytic anaemia only. Here we report on two siblings presenting with the characteristic haemolytic anaemia and a significant decrease in granulocyte function, both presumably as the result of GPI deficiency. Our data indicate that impairment of granulocyte function might be a more general feature of severe GPI deficiency than formerly noted.

Cell age dependent decay of human erythrocytes glucose-6-phosphate isomerase

Glucose-6-phosphate isomerase shows a biphasic decay pattern during red blood cell aging, which is very fast during the first part of cell's life span in circulation. This decay is not due to accumulation of inactive enzyme molecules, as shown by immunological studies, but is accompanied by the formation of secondary isozymes (i.e., chemically modified forms). Electrophoretic and ion-exchange chromatographic experiments show that glucose-6-phosphate isomerase (D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9) consists of only one isozymic form in young erythrocytes but is present in two components, with different electric charge, in mature and old cells. This secondary isozyme is more stable to heat treatment and is inactivated by IgG anti-glucose-6-phosphate isomerase with a lower affinity than the native isozyme. In vitro incubation of homogeneous human glucose-6-phosphate isomerase under conditions known to produce enzyme deamination does not reproduce the isozymic pattern found in erythrocytes, suggesting that one or more mechanisms other than those previously described to explain glucose-6-phosphate isomerase microheterogeneity occur in the human erythrocyte.