HbA Concentration Research Articles

Hemoglobin-induced contraction of pig pulmonary veins

The effects of hemoglobin A o (HbA o), αα cross-linked hemoglobin (ααHb), cyanomet αα cross-linked hemoglobin (cyanometααHb), and human serum albumin (HSA) were compared under basal conditions and during relaxation with acetylcholine (ACh), sodium nitroprusside (SNP), and papaverine (PAP) in porcine pulmonary veins. Isometric tension changes were recorded in isolated rings (3 to 4 mm) that were suspended in Krebs solution bubbled with 95% O 2/5% CO 2. Increasing concentrations of HbA o and ααHb (10 −9−3 × 10 −6 mol/L) caused concentration-dependent increases in tension that reached a maximum of 4.20 ± 0.3 gm and 3.78 ± 0.6 gm, respectively. CyanometααHb and HSA (10 −9− 3 × 10 −6mol/L) did not cause significant increases in tension. The maximum responses to HbA o and ααHb were significantly increased during relaxation with ACh and SNP but not with PAP. In contrast, SNP (10 −4 mol/L) and PAP (10 −5 mol/L), but not ACh, reversed contractions induced by HbA o and ααHb. These studies support the concept that hemoglobin-induced vascular contraction is primarily mediated by inactivation of the vasodilator nitric oxide in vitro. We suggest that this mechanism is common to acellular hemoglobins in which the ligand binding site is unimpaired and in which the heme iron is in the ferrous ( +2) state.

Relationship between Phenolic Acids Formed During Rumen Degradation of Maize Samples and in vitroDigestibility

The organic matter (OMD) and cell wall (CWD) digestibility of stalks of 25 different maize samples were determined in an in vitro assay using rumen fluid. The stalk OMD and CWD varied between 62-80% and 44-62%, respectively. The free phenolic acids formed in the liquid phase during fermentation in in vitro incubations were assessed by HPLC and 1H NMR. The following nine phenolic acids could be demonstrated to be present: p-hydroxybenzoic (HBA), p-hydroxyphenylacetic (HPAA), vanillic (VA), syringic (SYRA), 3-(4-hydroxyphenyl)propionic (HPPA), p-coumaric (PCA), ferulic (FA), phenylacetic(PAA) and 3-phenylpropionic (PPA) acids. Large variation was observed among the maize samples for all phenolic acids identified. The most abundant phenolic acids PPA, PAA and HPAA were present in concentrations ranging from 0·57 to 1·41 mM, 0·32 to 0·46 mM, and 71 to 105 μM, respectively, and were present as free monomeric molecules. HBA concentrations ranged from 6·9 to 21·1 μM and this acid was also present as free molecules. The other phenolic acids could only be observed after NaOH treatment of the liquid phase and were detected in minor amounts (0 to 12 μM). Correlation studies revealed a negative relation between digestibility and NaOH labile esters in the medium (ie PCA, FA, VA and SYRA esters) and a positive relationship between digestibility and PPA and PAA. When path analysis was applied, an inverse effect of PCA esters in the medium on both OMD and CWD (r = -0·71 and -0·56, respectively) was observed and a high positive effect of PPA acid on CWD (r = +0·67). Principal component analysis revealed close associations between released phenolic acid esters, neutral detergent fibre, and cell wall esters of PCA and FA.

Sex, Gestational Age, and Weight Dependancy of Adult Hemoglobin Concentration in Normal Newborns

We have measured by cation exchange high pressure liquid chromatography adult hemoglobin (HbA) concentration at birth in 6,123 unselected single newborn individuals. Probably because of the high precision of the analytical method used, we could demonstrate clear a relationship between HbA concentration and, respectively, gestational age and birth weight. We also demonstrated a significant difference in the Hb switching process between male and female newborns. Reference percentile distribution curves are given that could be used to define more precisely those children having slow or fast Hb switching.

Sex, gestational age, and weight dependancy of adult hemoglobin concentration in normal newborns

We have measured by cation exchange high pressure liquid chromatography adult hemoglobin (HbA) concentration at birth in 6,123 unselected single newborn individuals. Probably because of the high precision of the analytical method used, we could demonstrate clear a relationship between HbA concentration and, respectively, gestational age and birth weight. We also demonstrated a significant difference in the Hb switching process between male and female newborns. Reference percentile distribution curves are given that could be used to define more precisely those children having slow or fast Hb switching.

141 ACCELERATION OF THE SWITCH FROM FETAL TO ADULT HAEMOGLOBIN SYNTHESIS BY EXTRAUTERINE LIFE IN HUMAN NEWBORN INFANTS

Synthesis of human haemoglobin is directed by α-, β-, δ-, Glyγ- and Alaγ-genes. The switch from fetal to adult erythropoiesis includes a genetically controlled suppression of the γ- and activation of the β- and δ-chain synthesis. The two γ-genes are not equally inactivated. In animals external influences on the switch could be demonstrated, but no influence of extrauterine (EU) life on the switch in human newborns could be clearly demonstrated. The long half life of red cells hampers the detection of subtle influences on the switch by comparing the concentrations of HbA, HbF and HbA2. We studied therefor the de-novo synthesis of α-, β-, Alaγ- and Glyγ chains by measuring the incorporation of 3H-Leuctne into reticulocytes and subsequent separation of the globin chains by HPLC. 228 single measurements were obtained from 88 newborns (gestational age 26.3 to 42.1 weeks) at the age of 0 to 116 days; 16 babies were studied longitudinally. The results show that the switch γ→β is governed by the biological age (BA = intrauterine + EU age). A significant acceleration of the switch by EU life could be demonstrated: 1. The BA when 16 babies reached 50% (33%) of the full switch was not constant but correlated with GA: p<0.01 (p<0.05). 2. When 31 babies were studied at a BA of 40 to 43 weeks, a significant (p<0.02) acceleration of the switch was found in those with an EU age of 6 to 7 weeks (47%±21%, n=14) when compared to babies of 1 week ,or less of EU age (37%±25%, n=14). No comparable changes of the Alaγ/Glyγ-pattern was observed during the observation time of 26 to 43 weeks. Conclusion: γ→β-switch is accelerated by factors of EU life.Inactivation pattern of Alaγ/Glyγ is not concerted with the γ→β-switch.

Proton-Transferred Ion Pairs of p-Hydroxybenzaldehyde and p-Hydroxyacetophenone in Ethers at Low Temperature

Abstract The self-associations of p-hydroxybenzaldehyde (HBA) and p-hydroxyacetophenone (HAP) have been studied from measurements of phosphorescence and the excitation spectra at 77 K. At appropriately high concentrations of HBA and HAP in ethereal matrices, such as 1,4-dioxane, these compounds exhibit dual phosphorescences around 430 and 470 nm with excitation at 290 and 330 nm, respectively. The shorter-wavelength emission is due to monomeric species of the substrates. The longer-wavelength emission can be interpreted as being due to ion pairs, in which the proton of the hydroxyl group of the substrate molecule is transferred intermolecularly to the formyl group of another substrate molecule. The phosphorescence excitation spectra show that the ion pairs are formed in the ground states of the phenolic compounds, being in equilibrium with the monomeric species at 77 K. The ion pair formation is strongly dependent on the medium.

Early post-natal growth of large-for-dates babies of non-diabetic mothers is influenced by maternal glucose metabolism

Growth of weight, length, head circumference and skinfold thickness (subscapular and triceps) from birth to 6 months in 53 large-for-dates (LFD) Chinese babies weighing > 4.0 kg at term and born to non-diabetic mothers was investigated and correlated with biochemical indices of maternal glucose tolerance at birth: glycosylated haemoglobin (HbA 1), serum corrected fructosamine and the area under the oral glucose (50 g) tolerance (OGTT) curve. Growth in all physical dimensions, especially weight, showed a downward shift towards a reference mean. These changes in relative size were caused by slower growth velocities. None of the mothers had abnormally high concentrations of HbA, or fructosamine nor an abnormal OGTT. However, weight velocities did show small but significant correlations with fructosamine ( r = - 0.42), and OGTT area units ( r = 0.39) but not with HbA 1. For some macrosomic babies born to apparently normal mothers, birth is seen to interrupt a process operating in prenatal life that accelerates growth. Covert abnormalities of maternal glucose homeostasis could explain this. Abnormal glucose tolerance during pregnancy might therefore be viewed as a continuum extending from (i) its maximum expression, the frankly diabetic state, through (ii) gestational diabetes to (iii) the mother who has no biochemically evident abnormality of glucose homeostasis but who has sufficient alteration to modify fetal growth. Post-natal growth of LFD babies is additional information which, when taken along with other markers of maternal glucose tolerance, might help to identify the mother at later perinatal risk.

Unstable glycosylated hemoglobin in patients with diabetes mellitus

Incubation of washed erythrocytes for 4 h at 37°C in saline resulted in the disappearance of an unstable glycosylated fraction. In a reference group, its amount was very small, but its presence had a significant influence on the upper level of the reference range. In non-diabetic pregnant women, the unstable fraction was significantly higher than in the non-pregnant individuals, which resulted in a lower reference range for the stable HbA 1. In diabetic patients, the average unstable HbA 1 was about 10% of the “unincubated” level, with marked differences between individuals (0–30%), even in patients with a slightly elevated HbA 1. Therefore it is important to determine the concentration of stable HbA 1.

Monitoring Metabolic Control in Diabetic Outpatients with Glycosylated Hemoglobin

The usefulness of HbA, as a monitor of metabolic control was studied in 15 diabetic outpatients during periods of stable, deteriorating, and improving control. Mean fasting concentrations of HbA, and plasma glucose during a 3-month period of stable control were 12.6% +/- 0.8% and 120 +/- 8 mg/dL, respectively. One week after discontinuation of oral hypoglycemic therapy, blood glucose had risen to 172 +/- 23 mg/dL and HbA, to 14.1% +/- 0.7% (P less than 0.025). Reinstitution of therapy resulted in a significant fall of blood glucose within 2 weeks. A significant decline in HbA1 (from 15.3% +/- 0.8% to 14.1% +/- 0.9%, P less than 0.025) occurred 2 weeks later. The data show that the rate of formation of HbA1 is considerably faster than its rate of disappearance. Thus, HbA1 is likely to reflect disproportionally recent episodes of poor control. We conclude that HbA1 is useful to monitor diabetic outpatients during periods of stable and rapidly deteriorating control but is not suited to detect rapid metabolic improvements.

Hemoglobin F Koelliker (alpha2 minus 141 (HC 3) Arg gamma2); a modification of fetal hemoglobin.

An electrophoretically HbA-like hemoglobin component is produced in increasing amounts during storage in hemolysate preparations from macerated tissue (liver, kidney, spleen) of fetuses. Within twenty four hours after hemolysate preparation the "fast moving" fraction increases up to 40 per cent of total hemoglobin, while the concentration of HbA remains constant (5 - 7%) in hemolysates obtained from peripheral blood of the same donor individuals. By structural studies (fingerprint and aminoacid analysis) the HbA-like component was identified as an artefact of HbF, characterized by the absence of the C-terminal arginine of the alpha chains. From experimental data it is concluded, that the break down product results from a digestion of HbF by carboxypeptidase B, the enzyme being released from the macerated tissues. Analogous to a modification of HbA, i.e. Hb Koelliker (alpha2 minus 141 Arg beta2), the structure of the degradation product of HbF is alpha2 minus 141 Arg gamma2 (HbF Koelliker).