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PRESERVATION OF BLOOD FOR SUGAR ANALYSIS
310 Alteration of spMMWt.—Changes in the naked-eye appearance of the sputum were uncommon. In 3 cases the sputum, which was mucopurulent at the beginning, became more mucoid, but these alterations did not coincide with changes in drug treatment. In the patient whose graph is shown in fig. 4 the pronounced increase in expectoration was not accompanied by any qualitative change in sputum, which remained thick and purulent throughout the period of observation.
PRESERVATION OF BLOOD-SUGAR BY COPPER SULPHATE
CONCLUSION
Doses of ammonium carbonate six times greater than the maximal official dose rarely cause nausea. There is no evidence that either ammonium carbonate or ammonium chloride has any effect on expectoration in bronchitis. In chronic bronchitis and bronchiectasis with profuse secretion of sputum ammonium carbonate and ammonium chloride are not contra-indicated as is usually supposed ; but, on the other hand, the results of this investigation do not justify the view that they are of any value in these diseases. I am indebted to Prof. Noah Morris for his interest in this work and to Sister J. E. Rennie and Sister F. Robbie for their cooperation. Dr. Richard A. Robb of the mathematics department in the University of Glasgow kindly undertook a statistical examination of the results. REFERENCES
Alstead, S. (1939) Lancet, 2, 932. Gunn, J. A. (1927) Brit. med. J. 2, 972. Misgeld, J. F. (1934) Med. Welt, 8, 263.
PRESERVATION OF BLOOD FOR SUGAR ANALYSIS BY
E. J. KING, Ph.D. Toronto
R.T.
S. S. PILLAI, M.B. Madras, D.C.P.,
READER IN CHEMICAL PATHOLOGY AT THE BRITISH POSTGRADUATE MEDICAL SCHOOL
ASSISTANT IN THE DEPARTMENT
SUGAR disappears slowly from shed blood, and sugar analyses must therefore be made promptly after taking the blood samples, especially during the summer when higher room temperatures are encountered. Destruction is brought about by the glucolytic enzymes. of the blood or by bacterial action. This destruction may be inhibited by the addition of oxalate, fluoride, formaldehyde or thymol. These substances vary in their efficiency, the most effective agent being a mixture of 10 parts sodium fluoride with 1 part of thymol. A serious objection to the use of this mixture is that inferior grades of thymol, or solutions of thymol which have stood for a long time, may reduce the sugar reagent, thus giving erroneously high sugar values.
Copper
is
an
efficient anti-glucolytic agent.
It is also
used, together with tungstate (Somogyi 1931), as a deproteinising agent, and has proved to be one of the
most effective means of removing non-sugar-reducing substances from the blood. It therefore seemed probable that the addition of the copper sulphate to the blood at the time of its taking, instead of at the time of deproteinisation, might constitute a convenient means of preserving the specimen for sugar analysis. That it proved extremely effective in so doing is shown by the results in the table. REAGENTS
1. Isotonic sodium sulphate solution ; 3% w/v Na2S0.< IOH2O in water. 2. Copper sulphate solution; 7% w/v CuS04.5H2O in water. 3. Copper sulphate in isotonic sodium sulphate solution ; 30 ml. of the copper sulphate solution are mixed with 320 ml. of isotonic sodium sulphate. These are the proportions in which isotonic sodium sulphate and copper sulphate were used
in
our
previously
described method of
et al. 1937). 4. Sodium tungstate
(King
; 10% w/v
blood-sugar analysis
in water.
room
temperature.
METHOD
AND
D. BEALL, Ph.D. Toronto
=
Previous procedure2 ml. of blood was collected in 3-2 ml. of isotonic sodium sulphate. This was deproteinised with 03 ml. of sodium tungstate solution and 0 -3 ml. of copper sulphate solutions. The mixture was shaken, and filtered or centrifuged. Present p)’oce(hM’e.—Centrifuge tubes, or, more conveniently, screw-capped sample tubes ( x 4 in.) are charged with 3.5 ml. of copper sulphate in isotonic sodium sulphate solution, and 02 ml. specimens of capillary blood are rinsed into the contents of these tubes. The tubes are closed and left at room temperature until it is desired to complete the analysis. The blood-sugar appears to be stable for many hours and to increase slightly (rather than decrease) after several days. When it is desired to complete the analysis 0-3 ml. of sodium tungstate is added to each tube. The tubes are shaken and centrifuged or filtered. The supernatant fluids or filtrates obtained are quite clear and free of protein and non-sugar-reducing substances. For the analysis, 2 ml. (= 0-1 ml. of blood) is used with 2 ml. of alkaline copper sugar reagent. Some blood specimens-e.g., no. 6 in table-preserved in this way for more than three days at room temperature, or more than twelve hours at 37’ C., elaborated a nonfermentable reducing substance not removed by the copper tunstate. Such specimens therefore gave a raised blood-sugar "value. This phenomenon was encountered only occasionally, and only if specimens were kept for more than 72 hours at room temperature. It did not constitute a serious objection to the method, but is being investigated further. "
SUMMARY
Specimens for blood-sugar estimation may be preserved up to 72 hours at room temperature without alteration in the sugar content by collecting the blood in a mixture of sodium sulphate and copper sulphate solutions. REFERENCES
King, E. J., Haslewood, G. A. D. and Delory, G. E. (1937) Lancet, 1, 886 ; 2, 346. Somogyi, M. (1931) J. Biol. Chem. 90, 725.
PRESERVATION OF BLOOD-SUGAR BY COPPER SULPHATE
CONCLUSION
Doses of ammonium carbonate six times greater than the maximal official dose rarely cause nausea. There is no evidence that either ammonium carbonate or ammonium chloride has any effect on expectoration in bronchitis. In chronic bronchitis and bronchiectasis with profuse secretion of sputum ammonium carbonate and ammonium chloride are not contra-indicated as is usually supposed ; but, on the other hand, the results of this investigation do not justify the view that they are of any value in these diseases. I am indebted to Prof. Noah Morris for his interest in this work and to Sister J. E. Rennie and Sister F. Robbie for their cooperation. Dr. Richard A. Robb of the mathematics department in the University of Glasgow kindly undertook a statistical examination of the results. REFERENCES
Alstead, S. (1939) Lancet, 2, 932. Gunn, J. A. (1927) Brit. med. J. 2, 972. Misgeld, J. F. (1934) Med. Welt, 8, 263.
PRESERVATION OF BLOOD FOR SUGAR ANALYSIS BY
E. J. KING, Ph.D. Toronto
R.T.
S. S. PILLAI, M.B. Madras, D.C.P.,
READER IN CHEMICAL PATHOLOGY AT THE BRITISH POSTGRADUATE MEDICAL SCHOOL
ASSISTANT IN THE DEPARTMENT
SUGAR disappears slowly from shed blood, and sugar analyses must therefore be made promptly after taking the blood samples, especially during the summer when higher room temperatures are encountered. Destruction is brought about by the glucolytic enzymes. of the blood or by bacterial action. This destruction may be inhibited by the addition of oxalate, fluoride, formaldehyde or thymol. These substances vary in their efficiency, the most effective agent being a mixture of 10 parts sodium fluoride with 1 part of thymol. A serious objection to the use of this mixture is that inferior grades of thymol, or solutions of thymol which have stood for a long time, may reduce the sugar reagent, thus giving erroneously high sugar values.
Copper
is
an
efficient anti-glucolytic agent.
It is also
used, together with tungstate (Somogyi 1931), as a deproteinising agent, and has proved to be one of the
most effective means of removing non-sugar-reducing substances from the blood. It therefore seemed probable that the addition of the copper sulphate to the blood at the time of its taking, instead of at the time of deproteinisation, might constitute a convenient means of preserving the specimen for sugar analysis. That it proved extremely effective in so doing is shown by the results in the table. REAGENTS
1. Isotonic sodium sulphate solution ; 3% w/v Na2S0.< IOH2O in water. 2. Copper sulphate solution; 7% w/v CuS04.5H2O in water. 3. Copper sulphate in isotonic sodium sulphate solution ; 30 ml. of the copper sulphate solution are mixed with 320 ml. of isotonic sodium sulphate. These are the proportions in which isotonic sodium sulphate and copper sulphate were used
in
our
previously
described method of
et al. 1937). 4. Sodium tungstate
(King
; 10% w/v
blood-sugar analysis
in water.
room
temperature.
METHOD
AND
D. BEALL, Ph.D. Toronto
=
Previous procedure2 ml. of blood was collected in 3-2 ml. of isotonic sodium sulphate. This was deproteinised with 03 ml. of sodium tungstate solution and 0 -3 ml. of copper sulphate solutions. The mixture was shaken, and filtered or centrifuged. Present p)’oce(hM’e.—Centrifuge tubes, or, more conveniently, screw-capped sample tubes ( x 4 in.) are charged with 3.5 ml. of copper sulphate in isotonic sodium sulphate solution, and 02 ml. specimens of capillary blood are rinsed into the contents of these tubes. The tubes are closed and left at room temperature until it is desired to complete the analysis. The blood-sugar appears to be stable for many hours and to increase slightly (rather than decrease) after several days. When it is desired to complete the analysis 0-3 ml. of sodium tungstate is added to each tube. The tubes are shaken and centrifuged or filtered. The supernatant fluids or filtrates obtained are quite clear and free of protein and non-sugar-reducing substances. For the analysis, 2 ml. (= 0-1 ml. of blood) is used with 2 ml. of alkaline copper sugar reagent. Some blood specimens-e.g., no. 6 in table-preserved in this way for more than three days at room temperature, or more than twelve hours at 37’ C., elaborated a nonfermentable reducing substance not removed by the copper tunstate. Such specimens therefore gave a raised blood-sugar "value. This phenomenon was encountered only occasionally, and only if specimens were kept for more than 72 hours at room temperature. It did not constitute a serious objection to the method, but is being investigated further. "
SUMMARY
Specimens for blood-sugar estimation may be preserved up to 72 hours at room temperature without alteration in the sugar content by collecting the blood in a mixture of sodium sulphate and copper sulphate solutions. REFERENCES
King, E. J., Haslewood, G. A. D. and Delory, G. E. (1937) Lancet, 1, 886 ; 2, 346. Somogyi, M. (1931) J. Biol. Chem. 90, 725.