Magnetisable solid-phase separation fluoroimmunoassay for total oestriol in pregnancy serum.

A rapid separation fluoroimmunoassay for serum or plasma levels of total oestriol in pregnancy was established, based on the use of fluorescein-labelled oestriol and sheep anti-oestriol serum covalently linked to magnetisable particles. Equilibrium was attained within 10 min, and the fluorescence of the bound fraction of labelled ligand was quantitated fluorimetrically after elution from the magnetisable particles. Results for pregnancy serum samples correlated well with an established radioimmunoassay technique and the sensitivity, precision and accuracy were appropriate for clinical use. Advantages of this system as compared with radioimmunoassay include the speed and simplicity of end-point detection, prolonged shelf-life of the labelled reactant and absence of any health hazard. The separation step enabled the removal of any endogenous fluorophores or other interfering factors present in biological samples.

A direct fluoroimmunoassay for conjugated chenodeoxycholic acid using antibody coupling to magnetisable particles.

A novel solid phase fluoroimmunoassay for conjugated chenodeoxycholic acid has been developed employing an antiserum coupled to magnetisable cellulose particles and a chenodeoxycholyl glycinefluorescein thiocarbamyl ethylene diamine conjugate as the label. The data obtained from serum samples from 25 patients correlated closely (r = 0.99) with those obtained by radioimmunoassay. The assay is rapid (30 minutes), simple, and ideal for routine clinical purposes.

Conjugated bile acid and cholesterol levels in pregnant Africans and Caucasians.

Pregnancy serum glycochenodeoxycholic acid (GCDA) and taurochenodeoxycholic acid (TCDA) were simultaneously assayed by solid-phase fluoroimmunoassay (FIA) for apparently healthy Nigerians and caucasians domiciled in Nigeria and London respectively. Serum cholesterol values were also obtained for the same gestational period, that is, the second and third trimesters. The bile acid and cholesterol values were compared with those of their respective non-pregnant counterparts. Although there was a considerable fluctuation in the mean bile acid concentrations throughout this period for both pregnant groups, the mean bile acid value for each group was, however, within the normal range. The mean bile acid concentration for the pregnant African was significantly lower than that of her Caucasian counterpart, a notable factor in the assessment of hepatobiliary function for the African during pregnancy. Furthermore, a progressive rise in serum cholesterol during pregnancy, previously observed by other workers, was confirmed for both groups of women. But the increase in cholesterol concentration, which was greater in the Caucasian than the African, did not, however, appear to have affected the bile acid concentration during pregnancy.

Sickle cell disease: some haematological changes in steady state and crisis.

Blood was collected from HbSS-confirmed sicklers (80 males and 75 females, age 2-26 and 1-27 years, respectively) who attended our clinics. They were either on crisis or steady state. Blood analysis showed that, both in steady state and crisis, haematological indices are categorizable into three: those that show marginal changes between crises and steady states, irrespective of sex. These include PCV, MCMC, % eosinophil and monocyte/basophil counts; those that vary significantly in both states, mainly in female sufferers, for example bilirubin and % neutrophils; those that show appreciable changes in males. These include mean cell volume and haemoglobin concentration. There are therefore clear haematological changes in steady state and crisis in sickle cell disease (SCD). Some appear to be sex-influenced, a factor of which must be taken into account in the use of haematological data either as crisis markers or therapeutic monitors.

The antisickling role of uric acid in sickle cell disease.

Based on the antisickling properties of structurally similar compounds, uric acid (urate) was investigated and found to possess antisickling activity on sickle cell erythrocytes, in particular at higher urate concentrations. Serum urate levels were subsequently determined for 60 sickle cell patients of both sexes within the age limit of 1-27 years. The mean serum urate values were computed at discrete age groups, and the values obtained were compared with the mean serum urate concentration for 15 normal subjects of both sexes and similar age range. Although a definite age-dependent trend did exist in the mean serum urate concentration in sickle cell disease (SCD), this elevation could not be truly referred to as "hyperuricaemia'. Hence, any possible contribution by elevated serum urate to a gouty trait and SCD bone crisis remains unclear. However, these observed serum urate values corresponded well with those concentrations which inhibited the sickling of sickle cell erythrocytes in vitro, permitting the speculation that the elevated serum urate might well be beneficial to sickle cell patients in a compensatory way.

Plasma urea in pregnant urban African and Caucasian women.

Plasma urea concentrations were determined for 109 pregnant Caucasian women and 117 pregnant urban African women covering the last two trimesters of pregnancy. Elevation of the urea level was observed in both populations. The elevation was progressive in both cases. The urea levels for Caucasians were apparently normal until about the thirteenth week of gestation when it rose to above normal level and increased progressively in the third trimester. For the Africans, the progressive rise was similar but the values did not exceed the normal range until after the thirty-second week of gestation. Thus, a general pattern of variation which is similar in both Caucasians and Africans exists for the plasma urea level during pregnancy. However, the levels for Caucasians over the gestational periods are consistently higher than the level for Africans. The increase in the level of this non-protein nitrogen compound was attributed to increased intake of proteinous foods and is probably a result of diminished excretion of urea arising from pre-renal causes such as volume depletion.

The Reversion of Sickled Cells by Cajanus cajan.

Boiled and crude ethanolic extracts of edible CAJANUS CAJAN beans were prepared and used for IN VITRO studies involving 14 individual blood samples obtained from confirmed sickle cell (HbSS) patients. It was demonstrated that the extracts were able not only to inhibit sickling in sodium metabisulphite solution, but also quickly reverted to normal morphology, already sickled erythrocytes. There was also a noticeable improvement in the general morphology of the sickle cell erythrocytes after coming into contact with the plant extracts.

Phenylalanine is the predominant antisickling agent in Cajanus cajan seed extract.

Amino acid analysis showed that solvent extracts of Cajanus cajan L. Millsp. (Fabaceae) seeds (white species) contain, as free amino acid, as much as 26.3% phenylalanine. Antisickling experiments based on the estimated amount of free phenylalanine in the methanol (water-soluble) extract of the seeds showed that the presence of this amino acid alone could account for about 70% of the antisickling potency of Cajanus cajan seed extract.

Sialic acid in sickle cell disease.

Neuraminic (sialic) acid concentrations in serum from normal and sickle cell (HbSS) subjects were determined for discrete age groups from childhood through adolescence. Values in sickle cell disease were consistently lower over the entire age range. We further investigated the effect of exogenous sialic acid on the rate of sickling reversion of HbSS erythrocytes and demonstrated that this compound in millimole per liter concentrations could revert pre-sickled erythrocytes to their normal morphology in a concentration-dependent manner. When subjected to partial de-sialation with sialidase (EC 3.2.1.18), the HbSS erythrocytes not only sickled faster upon deoxygenation, they also reverted more slowly on treatment with phenylalanine (a more efficient anti-sickling agent than sialic acid) than did untreated cells. We conclude that, in sickle cell disease, erythrocyte sialic acid content could play a significant role, not only in the control of the sickling rate in vivo, but also, after sickling has occurred, in the rate of recovery from a sickling crisis.

Serum creatinine and uric acid levels in pregnant urban African and Caucasian women.

Serum creatinine and uric acid concentrations were determined for 117 pregnant urban African women and 109 pregnant Caucasian women covering the three trimesters of pregnancy. The creatinine levels for Caucasians rose as pregnancy progressed, exceeding the normal adult level, while that for Africans rose only slightly and only during the last trimester of pregnancy. A similar observation was made for uric acid levels except that the rise in Africans commenced earlier than it did for creatinine, commencing from about the second trimester. Also, the levels in both groups of people remained within the normal adult range. The increased levels of these non-protein nitrogen compounds during pregnancy was attributable to increased metabolism associated with the condition. The difference observed between the Caucasians and Africans was attributed to the better protein nutritional status of the former. It is suggested that the creatinine "curve" especially for the Caucasians could be utilized in the monitoring of foetal well-being.

Serum calcium and protein in haemoglobin-SS patients.

Total serum calcium, total serum protein and albumin were estimated in haemoglobin-SS patients. The same estimations were carried out on a control group consisting of subjects from the same locality and similar age ranges. It was observed that the serum calcium level was significantly lower in haemoglobin-SS patients while total serum protein was significantly elevated in these same patients.

Serum sodium and potassium values in pregnant urban Nigerian and Caucasian women.

Serum sodium and potassium values were determined in the same laboratory for 250 pregnant urban Africans, 31 non-pregnant urban Africans and 155 pregnant Caucasians. The non-pregnant urban African women had significantly higher average serum sodium concentration than both pregnant groups. There was a progressive decline in serum sodium in both groups of pregnant women starting from the end of the first trimester to term. The decline in sodium concentration did not approach the level of hyponatraemia as previously reported. The fall in serum sodium concentration during pregnancy is probably a general phenomenon for pregnant women. The serum potassium concentration of the pregnant African women was not significantly higher than that of their non-pregnant counterparts. However, in pregnant Caucasians it was significantly higher than in pregnant and non-pregnant Africans. Serum potassium concentrations showed no significant variation during pregnancy.

Serum calcium and protein levels in pregnant African and Caucasian women.

Serum calcium and protein concentrations were determined for 243 pregnant urban African and 150 Caucasian women covering the three trimesters of pregnancy. It was shown that the serum protein content of the pregnant African was consistently lower than that of her Caucasian counterpart, probably as a result of environmental and nutritional factors. On the other hand, there appeared to be little difference in the serum calcium concentration of both groups up to the end of the second trimester; thereafter, the serum calcium of the pregnant African began to increase significantly above that of the Caucasian up to term (without hypercalcaemia), whereas the Caucasian calcium concentration remained virtually unchanged. It is therefore concluded that this phenomenon is a compensatory mechanism through which the increasing need of the foetus for calcium was adequately satisfied by mobilization of calcium from its depot.

Studies on human erythrocyte glutathione-S-transferase from HbAA, HbAS and HbSS subjects.

The activities of human erythrocyte glutathione-S-transferase (EC 2.5.1.18) obtained from 53 subjects of both sexes aged between 5 and 25 years of HbAA (20), HbAS (13) and HbSS (20) were determined. The results, expressed in IU/g Hb, obtained for the various genotypes were: HbSS = 14.6 +/- 3.4; HbAS = 4.7 +/- 1.1; HbAA = 2.7 +/- 0.8. The observed differences were found to be statistically significant (p less than 0.001). Kinetic analysis showed similar Michaelis constants (Km) of the enzyme irrespective of the genotype, indicating structural and functional similarities of the enzyme from the various genotypes. A mean (+/- SD) percentage increase of 63.8 +/- 4.9 was obtained for the red cell glutathione-S-transferase activity in the presence of dithionite, while a mean (+/- SD) decrease of 38.8 +/- 1.9% was obtained in the presence of 0.3 mM haemin. These findings suggest an increased activation of the enzyme in HbSS and HbAS subjects (as compared with HbAA subjects) possibly by an increased generation of electrophilic substrates in the red cell of these subjects.