- Email: [email protected]
KARYOTYPE AND COLCHICINE-EXPOSURE TIME
372 The results also suggest, however, that it is the side of slightly longer exposure to demecolcine, since there are more good cells available at 150 minutes than at 90 minutes. The data presented here, therefore, support the statement of Miss Breau and her colleagues that there is an increase in the total number of analysable mitoses with longer exposure to colchicine.
cells.
typable better
to err on
University Department of Medical Genetics, Royal Infirmary, Manchester 13.
IONIC
STRENGTH
Urinary calcium concentrations and ionic strengths subjects (0) and 13 patients with renal stones (.).
in 50 normal
Urinary calcium concentrations and ionic strengths, as measured in 50 normal subjects and 13 patients with renal stones, are shown in the accompanying figure. The two groups are seen to be clearly demarcated. At any given calcium concentration, the stone-formers’ urines are of lower ionic strength than those of the controls. Detailed
experimental and clinical data substantiating the argument
given here have been submitted for publication elsewhere. Endocrine-Metabolic Research Group,
Department of Medicine, University of Cape Town.
L. C. ISAACSON.
KARYOTYPE AND COLCHICINE-EXPOSURE TIME
STANDARDS OF OBSTETRIC CARE SIR,-I have read with interest your leading articleand the subsequent letter by Dr. Mac Keith (July 1, p. 52). I should like to suggest with much deference to my former teacher, Dr. Mac Keith, that the index of the standard of obstetric care should cover a wider field than the problem of " whether the incidence of low birth weight falls fast enough ". The current concepts of the high-risk mother and the high-risk infant are valuable aids in defining who may need the most help, but surely the aim of obstetric care should be to produce a high-quality baby for every mother. The true index of longterm obstetric care being how far short we fall from this standard. In order to raise the status and promote interest in the emergent science of obstetrics, postgraduate training of physicians for leadership in this field should include psychology, human genetics, embryology, teratology, neonatal pxdiatrics, nutrition, public health, and probably anxsthesia. This could be accomplished by separating obstetrics from the traditional but time-consuming ties with gynxcology. Endocrine-Metabolic Laboratory, University of Texas, Medical Branch
SIR,-The letter by Miss Breau and her colleagues (July 15, p. 151) prompts me to refer to my own observations on the
peripheral-blood chromosome cultures to demecolcine (’ Colcemid ’) for different times. Using the same sample of venous blood six 10 ml. cultures were set up, using ’TC 199 ’ (Glaxo) and phytohxmagglutinin P (Difco), and grown for 72 hours at 37°C. 0-2 ml. of demecolcine, at a concentration of 1 mg. in 100 ml. of TC 199, was then added to each culture. The first culture was harvested after 30 minutes at 37°C and the other five at 30-minute intervals thereafter. Each culture was treated with hypotonic saline solution for 15 minutes at 37°C, fixed with acetic-acid/alcohol, spread on to cold slides, air-dried, and treated with 10% Giemsa’s stain at pH 64. The effect of different exposure-times was determined, firstly, by estimating the mitotic index, here expressed as the
J. TIMSON.
Galveston.
NORMA WILLIAMS.
exposure of
ŒDEMA IN PREGNANCY
leading article (July 22, p. 197) you draw interesting finding of Thomson and his that oedematous mothers have babies significantly colleagues larger than those born to non-oedematous mothers. Similarly I showed2 that the weights of babies of mothers who had to be induced because of exacerbation of their hypertension were SIR,-In
attention
your the
to
those of the mothers who went to term. Do these findings not suggest that it is the big baby that causes the nephropathy which lies behind oedema and hypertension ? British Hospital for Mothers and Babies, C. K. VARTAN. Woolwich, London S.E.18. as
great
as
two
MITOTIC INDICES AND GRADES OF METAPHASE FIGURES AFTER EXPOSURE OF PERIPHERAL-BLOOD CULTURES TO DEMECOLCINE
number of mitoses per 1000 cells (2000 cells counted per culture), and, secondly, by classifying 50 mitoses from each culture into three grades. In grade-I cells the chromosomes were well spread and distinct (i.e., easy to karyotype), in grade-n cells the chromosomes could be counted but karyotyping would not be easy, and grade III included all other cells in mitosis. The results given in the accompanying table indicate that the optimum exposure-time using this concentration of demecolcine, in terms both of number of cells in mitosis and percentage of grade-i cells, was 120 minutes. Increased exposure decreased both the mitotic index and the proportion of karyo-
PREGNANCY TESTS AND PROTEINURIA SIR,-We were interested to read the letters from Dr. Kew and his colleagues 3 and Dr. Warrack and Dr. Richards4 on misleading results of immunological pregnancy tests in patients with proteinuria, since we also have investigated this problem.5 We have found, in agreement with other workers, that commercial human-chorionic-gonadotrophin (H.C.G.) preparations are contaminated with 7-8 antigenic proteins. Unspecific activity, however, was only demonstrable in «1-globulin when eluted agar-gel electrophoretical regions were examined separately in the haemagglutination-inhibition test. We have therefore analysed normal human serum, serum and urine extract of pregnant women, and urine extract from normal people and from patients with nephrosis in the same manner. Again unspecific activity of all tested specimens was attributed Further studies in gel filtration on to an «1-globulin. ’ and G-200 ’ Sephadex chromatography on diethylaminoethyl1. 2. 3. 4. 5.
Lancet, 1967, i, 1367. Vartan, C. K. Proc. R. Soc. Med. 1967, 59, 843. Kew, M. C., Seftel, H. C., Bloomberg, B. M. Lancet, 1967, i, 902. Warrack, A. K. N., Richards, H. ibid. p. 957. Rohde, W., Dorner, G. Acta biol. med. germ. 1966, 16, 683; unpublished.
cells.
typable better
to err on
University Department of Medical Genetics, Royal Infirmary, Manchester 13.
IONIC
STRENGTH
Urinary calcium concentrations and ionic strengths subjects (0) and 13 patients with renal stones (.).
in 50 normal
Urinary calcium concentrations and ionic strengths, as measured in 50 normal subjects and 13 patients with renal stones, are shown in the accompanying figure. The two groups are seen to be clearly demarcated. At any given calcium concentration, the stone-formers’ urines are of lower ionic strength than those of the controls. Detailed
experimental and clinical data substantiating the argument
given here have been submitted for publication elsewhere. Endocrine-Metabolic Research Group,
Department of Medicine, University of Cape Town.
L. C. ISAACSON.
KARYOTYPE AND COLCHICINE-EXPOSURE TIME
STANDARDS OF OBSTETRIC CARE SIR,-I have read with interest your leading articleand the subsequent letter by Dr. Mac Keith (July 1, p. 52). I should like to suggest with much deference to my former teacher, Dr. Mac Keith, that the index of the standard of obstetric care should cover a wider field than the problem of " whether the incidence of low birth weight falls fast enough ". The current concepts of the high-risk mother and the high-risk infant are valuable aids in defining who may need the most help, but surely the aim of obstetric care should be to produce a high-quality baby for every mother. The true index of longterm obstetric care being how far short we fall from this standard. In order to raise the status and promote interest in the emergent science of obstetrics, postgraduate training of physicians for leadership in this field should include psychology, human genetics, embryology, teratology, neonatal pxdiatrics, nutrition, public health, and probably anxsthesia. This could be accomplished by separating obstetrics from the traditional but time-consuming ties with gynxcology. Endocrine-Metabolic Laboratory, University of Texas, Medical Branch
SIR,-The letter by Miss Breau and her colleagues (July 15, p. 151) prompts me to refer to my own observations on the
peripheral-blood chromosome cultures to demecolcine (’ Colcemid ’) for different times. Using the same sample of venous blood six 10 ml. cultures were set up, using ’TC 199 ’ (Glaxo) and phytohxmagglutinin P (Difco), and grown for 72 hours at 37°C. 0-2 ml. of demecolcine, at a concentration of 1 mg. in 100 ml. of TC 199, was then added to each culture. The first culture was harvested after 30 minutes at 37°C and the other five at 30-minute intervals thereafter. Each culture was treated with hypotonic saline solution for 15 minutes at 37°C, fixed with acetic-acid/alcohol, spread on to cold slides, air-dried, and treated with 10% Giemsa’s stain at pH 64. The effect of different exposure-times was determined, firstly, by estimating the mitotic index, here expressed as the
J. TIMSON.
Galveston.
NORMA WILLIAMS.
exposure of
ŒDEMA IN PREGNANCY
leading article (July 22, p. 197) you draw interesting finding of Thomson and his that oedematous mothers have babies significantly colleagues larger than those born to non-oedematous mothers. Similarly I showed2 that the weights of babies of mothers who had to be induced because of exacerbation of their hypertension were SIR,-In
attention
your the
to
those of the mothers who went to term. Do these findings not suggest that it is the big baby that causes the nephropathy which lies behind oedema and hypertension ? British Hospital for Mothers and Babies, C. K. VARTAN. Woolwich, London S.E.18. as
great
as
two
MITOTIC INDICES AND GRADES OF METAPHASE FIGURES AFTER EXPOSURE OF PERIPHERAL-BLOOD CULTURES TO DEMECOLCINE
number of mitoses per 1000 cells (2000 cells counted per culture), and, secondly, by classifying 50 mitoses from each culture into three grades. In grade-I cells the chromosomes were well spread and distinct (i.e., easy to karyotype), in grade-n cells the chromosomes could be counted but karyotyping would not be easy, and grade III included all other cells in mitosis. The results given in the accompanying table indicate that the optimum exposure-time using this concentration of demecolcine, in terms both of number of cells in mitosis and percentage of grade-i cells, was 120 minutes. Increased exposure decreased both the mitotic index and the proportion of karyo-
PREGNANCY TESTS AND PROTEINURIA SIR,-We were interested to read the letters from Dr. Kew and his colleagues 3 and Dr. Warrack and Dr. Richards4 on misleading results of immunological pregnancy tests in patients with proteinuria, since we also have investigated this problem.5 We have found, in agreement with other workers, that commercial human-chorionic-gonadotrophin (H.C.G.) preparations are contaminated with 7-8 antigenic proteins. Unspecific activity, however, was only demonstrable in «1-globulin when eluted agar-gel electrophoretical regions were examined separately in the haemagglutination-inhibition test. We have therefore analysed normal human serum, serum and urine extract of pregnant women, and urine extract from normal people and from patients with nephrosis in the same manner. Again unspecific activity of all tested specimens was attributed Further studies in gel filtration on to an «1-globulin. ’ and G-200 ’ Sephadex chromatography on diethylaminoethyl1. 2. 3. 4. 5.
Lancet, 1967, i, 1367. Vartan, C. K. Proc. R. Soc. Med. 1967, 59, 843. Kew, M. C., Seftel, H. C., Bloomberg, B. M. Lancet, 1967, i, 902. Warrack, A. K. N., Richards, H. ibid. p. 957. Rohde, W., Dorner, G. Acta biol. med. germ. 1966, 16, 683; unpublished.