HPLC determination of biologically active thiols using pre-column derivatisation with 5,5'-dithio-(bis-2-nitrobenzoic acid).

5,5'-Dithio-(bis-2-nitrobenzoic acid), Ellmans reagent (ESSE), is used as a pre-column derivatisation reagent for the determination of biologically active thiols by HPLC. D-penicillamine, N-acetyl-d-penicillamine, N-acetylcysteine, cysteine, captopril and thiomalic acid all give well resolved derivatives. The calibration graph and reproducibility (%R.S.D. +/- 1.3%) for the analysis of glutathione indicates that the method could be used for quantitative analysis. ESSE is widely used as a reagent in thiol determinations by electronic spectroscopy via the detection of the Ellmans anion (ES-) generated without any prior separation procedures. However, there are considerable reservations over its use for the spectrophotometric determination of thiols because of the possibility of side reactions which generate another Ellmans based species (ESO2-). The assay described determines the thiol as a derivatised mixed disulphide (ESSR) and since speciation between the anion ES- and the oxidation product ESO2- occurs it enables the process of oxidation to be monitored simultaneously.

A diagnostic survey of infants referred for chromosome analysis in the neonatal period.

Examination and assessment of 140 liveborn and stillborn infants referred within two weeks of birth for chromosome analysis showed that 48 had Down's syndrome, 12 other chromosome abnormalities, 17 single gene disorders, 18 recognisable anomalads, 8 recognisable syndromes of unknown aetiology, and the remainder were undiagnosed. Of the non-Down's cases that were diagnosed, 21% had a chromosomal abnormality. These results suggest that a request for chromosome analysis in the newborn period should be viewed as one step in syndrome identification.

Partial monosomy 7 with interstitial deletions in two infants with differing congenital abnormalities.

Two cases of interstitial deletion of chromosome 7 are presented, one involving the short arm and the other the long arm. The cytogenetic, dermatoglyphic, and clinical findings are compared with previously reported cases of chromosome 7 deletion. The patient with a short arm deletion differs clinically from the previously reported cases but, in common with a least one previous case, has a low total finger ridge count. His interstitial deletion involving the 7p13 leads to 7p21 region also differs from 7p deletions reported in earlier cases. The patient with a long arm deletion has an interstitial loss of the region between 7q11 and 7q21, corresponding to one of three groups of 7q deletion that have been recognised. The phenotypic changes in this group are less well defined than in the other two and the patient presented here differs clinically from the previously reported cases, apart from one phenotypically normal mosaic case, in lacking morphological abnormalities. He shares with one previous case both epilepsy and a high intensity of dermal ridge patterns.

11q aneuploidy: partial monosomy and trisomy in the children of a mother with a t(3;11)(p27;q23) translocation.

A woman with a balanced translocation t(3;11)(p27;q23) has had three abnormal children. The first child died in infancy, and of the two survivors who show segregation of the derivative maternal translocated chromosomes, one exhibits partial trisomy 11q and the other partial monosomy 11q. The two cases are compared with each other and with reported examples. Moreover, 11q break points are discussed.

Trisomy 16q arising from a maternal 15p;16q translocation.

Trisomy 16q is reported in a malformed infant who died at 12 days of age. The karyotype was 46,XX,der(15)t(15;16) (p11;q11)mat. A balanced translocation was found in the mother. The consequences of various types of aneuploidy of chromosome 16 are discussed.