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EFFICIENCY OF ARTIFICIAL KIDNEYS
540
0-4%-a result within normal limits. Vertical strip electrophoresis, performed at pH 8-6,3 showed no abnormal hwmoglobin, while the level of erythrocyte glucose-6-phosphate dehydrogenase (performed by Dr. B. Hearn, Lewisham
was
Hospital, S.E.13
was
normal.
Guy’s Hospital, London, S.E.1.
RONALD D. BARNES.
EXCRETION OF 5-HYDROXYINDOLYLACETIC ACID IN EAST AFRICANS
SIR,-We read with interest the article of Feb. 17 by Dr. Crawford on this subject. We have observed that there is a raised excretion of this substance in white male Europeans following surgery. This is being reported in detail elsewhere, but we draw attention to it now because other workers investigating this subject might encounter otherwise certain confusions when selecting patients for their studies. Division of Wound Healing Research, Department of Surgery, University of Birmingham.
GEORGE T. WATTS.
EFFICIENCY OF ARTIFICIAL KIDNEYS SIR,-Kennedy et al. describe the efficiency of a modified rotating-drum artificial kidney. Through this modifica-
they have achieved an appreciable increase in efficiency with a corresponding decrease in dialysing time.
tion
We think their result represents
a
valuable and
an
important improvement. possible to increase the dialysing surface area by 12-5% (compared with Parsons and McCracken 5) without increasing the amount of blood needed for priming the kidney. We do not think this volume is of major importance as long as it does not change significantly when the blood-flow changes during dialysis, and as long as it is not unreasonably large. If the efficiency of different types of haemodialysers is to be compared, we think that clearance (or dialysance) values calculated from data obtained during actual clinical use are
pressures the ultrafiltration may to more than 1000 ml. per hour.
In full agreement with Kennedy et al., we too have found that even very fast correction of the patient’s chemical disturbances has never led to any untoward effects. Among the several advantages of short and efficient
dialyses
3. 4. 5.
Lehmann, H., Smith, E. B. Trans. R. Soc. trop. Med. Hyg. 1954, 48, 12. Kennedy, A. C., Gray, M. J. B., Dinwoodie, A., Linton, A. L. Lancet, 1961, ii, 996. Parsons, F. M., McCracken, B. H. Brit. J. Urol. 1958, 30, 463.
are:
(1) Longer intervals between each dialysis when more than dialysis is necessary. This gives more time available for the vitally important treatment of the precipitating conditions or complications, often including surgery. (2) Lower average level of uraemia during the period of one
renal failure. (3) Smaller amounts of heparin required. (4) Less strain on everybody-the patient, nurses, and doctors. In one type of case it is of decisive importance to per-
form a fast and efficient dialysis-poisoning with dialysable agents. Our experience is so far limited to poisoning with bromide, methyl alcohol, ethyl alcohol, isoniazid, and salicylate, but undoubtedly this treatment should always be considered when the poison is of low molecular weight and not strongly bound to proteins. HANS E. JØRGENSEN Kommunehospitalet, JØRGEN T. BALSLØV Copenhagen, CLAUS U. BRUN. Denmark. BIRTH ORDER AND MATERNAL AGE OF HOMOSEXUALS
It has been
far better parameters than estimation of the amount of dialysable substances recovered in the dialysing bath, or the corresponding drop in blood concentrations. Apart from differences in efficiency in different types of dialysers, the amount of recovered urea (or other substances) in the dialysing bath depends on the total body water of the patient, the plasma-urea before dialysis, and the duration of the dialysis. Since 1954 we have used the Skeggs-Leonard hsemodialyser, now modified to a dialysing surface area of 43 sq. m. The dialyser is primed with 800 ml. of blood. The blood of the patient is taken from the inferior vena cava through a polyethylene catheter (internal diameter 3-3-5 mm.) and returned through a similar catheter in an arm vein. The blood-flow is about 800 ml. per min. and the dialysing fluid flow 3000 ml. per min., giving urea-clearances of 350450 ml. per min. The urea-clearance per sq. m. of dialysing surface is 100 ml. per min. Kennedy et al. have a urea-clearance of 70 ml. per min. per sq. m. (calculated from their fig. 1). The difference is probably due to a difference in the thickness of the dialysing membranes. We use Cuprophan PT 150 ’ which is a very thin brand ofCellophane ’ (approximately 11 li thick) Our patients are usually dialysed when their serum-urea reaches 300-350 mg. per 100 ml. A dialysis is carried out in 3-31/2 hours and the serum-urea at the end of dialysis is in the range of 60-70 mg. per 100 ml. In the modified Skeggs-Leonards hsemodialyser the hydrostatic pressure gradient over the dialysing membrane is continuously monitored and easily controlled. The dialyser will, if needed, work as an ultrafilter without the use of extra glucose in the dialysing fluid. By changing the hydrostatic
easily be changed from zero
SIR,-Dr. Slater’s method of analysis of the birth order sample of male homosexuals, although suited to his
in his
purpose, does not do justice to the points of relevance to an environmental theory of homosexuality. They have not been brought out clearly in his paper (Jan. 13) or in the ensuing correspondence (Jan. 27 and Feb. 17). Let us examine in a different way the data contained in table i of his paper, proceeding as follows. Omit the only children. Classify the other cases as first in birth order, last, " second " (except those also last), " penultimate " (except those also first or second) or " middle " (the remainder). Count the cases in each class. Calculate the number to be expected from the null hypothesis that the cases occur independently of birth order. (The number of cases to be expected in any given place in the table is obtained by dividing the number of cases of that size of sibship by the number in the sibship). For our purpose this classification and procedure appears to be the best of the several similar ones which might be suggested. We obtain these figures:
The null hypothesis can be rejected. In this sample there is of cases which are last in the sibship. There is no " excess of those which are penultimate ", nor of" those which are first. There are relatively few which are second" or " middle ".
an excess
This pattern of distribution does not of course decide between Dr. Slater’s hypothesis that maternal age is the crucial variable and a hypothesis that homosexuality in the male arises out of a distorted relationship with the mother. From the point of view of the latter hypothesis, the pattern observed corresponds reasonably well to what might be suggested if closeness of the relationship with the mother is taken to be a factor in aetiology.
0-4%-a result within normal limits. Vertical strip electrophoresis, performed at pH 8-6,3 showed no abnormal hwmoglobin, while the level of erythrocyte glucose-6-phosphate dehydrogenase (performed by Dr. B. Hearn, Lewisham
was
Hospital, S.E.13
was
normal.
Guy’s Hospital, London, S.E.1.
RONALD D. BARNES.
EXCRETION OF 5-HYDROXYINDOLYLACETIC ACID IN EAST AFRICANS
SIR,-We read with interest the article of Feb. 17 by Dr. Crawford on this subject. We have observed that there is a raised excretion of this substance in white male Europeans following surgery. This is being reported in detail elsewhere, but we draw attention to it now because other workers investigating this subject might encounter otherwise certain confusions when selecting patients for their studies. Division of Wound Healing Research, Department of Surgery, University of Birmingham.
GEORGE T. WATTS.
EFFICIENCY OF ARTIFICIAL KIDNEYS SIR,-Kennedy et al. describe the efficiency of a modified rotating-drum artificial kidney. Through this modifica-
they have achieved an appreciable increase in efficiency with a corresponding decrease in dialysing time.
tion
We think their result represents
a
valuable and
an
important improvement. possible to increase the dialysing surface area by 12-5% (compared with Parsons and McCracken 5) without increasing the amount of blood needed for priming the kidney. We do not think this volume is of major importance as long as it does not change significantly when the blood-flow changes during dialysis, and as long as it is not unreasonably large. If the efficiency of different types of haemodialysers is to be compared, we think that clearance (or dialysance) values calculated from data obtained during actual clinical use are
pressures the ultrafiltration may to more than 1000 ml. per hour.
In full agreement with Kennedy et al., we too have found that even very fast correction of the patient’s chemical disturbances has never led to any untoward effects. Among the several advantages of short and efficient
dialyses
3. 4. 5.
Lehmann, H., Smith, E. B. Trans. R. Soc. trop. Med. Hyg. 1954, 48, 12. Kennedy, A. C., Gray, M. J. B., Dinwoodie, A., Linton, A. L. Lancet, 1961, ii, 996. Parsons, F. M., McCracken, B. H. Brit. J. Urol. 1958, 30, 463.
are:
(1) Longer intervals between each dialysis when more than dialysis is necessary. This gives more time available for the vitally important treatment of the precipitating conditions or complications, often including surgery. (2) Lower average level of uraemia during the period of one
renal failure. (3) Smaller amounts of heparin required. (4) Less strain on everybody-the patient, nurses, and doctors. In one type of case it is of decisive importance to per-
form a fast and efficient dialysis-poisoning with dialysable agents. Our experience is so far limited to poisoning with bromide, methyl alcohol, ethyl alcohol, isoniazid, and salicylate, but undoubtedly this treatment should always be considered when the poison is of low molecular weight and not strongly bound to proteins. HANS E. JØRGENSEN Kommunehospitalet, JØRGEN T. BALSLØV Copenhagen, CLAUS U. BRUN. Denmark. BIRTH ORDER AND MATERNAL AGE OF HOMOSEXUALS
It has been
far better parameters than estimation of the amount of dialysable substances recovered in the dialysing bath, or the corresponding drop in blood concentrations. Apart from differences in efficiency in different types of dialysers, the amount of recovered urea (or other substances) in the dialysing bath depends on the total body water of the patient, the plasma-urea before dialysis, and the duration of the dialysis. Since 1954 we have used the Skeggs-Leonard hsemodialyser, now modified to a dialysing surface area of 43 sq. m. The dialyser is primed with 800 ml. of blood. The blood of the patient is taken from the inferior vena cava through a polyethylene catheter (internal diameter 3-3-5 mm.) and returned through a similar catheter in an arm vein. The blood-flow is about 800 ml. per min. and the dialysing fluid flow 3000 ml. per min., giving urea-clearances of 350450 ml. per min. The urea-clearance per sq. m. of dialysing surface is 100 ml. per min. Kennedy et al. have a urea-clearance of 70 ml. per min. per sq. m. (calculated from their fig. 1). The difference is probably due to a difference in the thickness of the dialysing membranes. We use Cuprophan PT 150 ’ which is a very thin brand ofCellophane ’ (approximately 11 li thick) Our patients are usually dialysed when their serum-urea reaches 300-350 mg. per 100 ml. A dialysis is carried out in 3-31/2 hours and the serum-urea at the end of dialysis is in the range of 60-70 mg. per 100 ml. In the modified Skeggs-Leonards hsemodialyser the hydrostatic pressure gradient over the dialysing membrane is continuously monitored and easily controlled. The dialyser will, if needed, work as an ultrafilter without the use of extra glucose in the dialysing fluid. By changing the hydrostatic
easily be changed from zero
SIR,-Dr. Slater’s method of analysis of the birth order sample of male homosexuals, although suited to his
in his
purpose, does not do justice to the points of relevance to an environmental theory of homosexuality. They have not been brought out clearly in his paper (Jan. 13) or in the ensuing correspondence (Jan. 27 and Feb. 17). Let us examine in a different way the data contained in table i of his paper, proceeding as follows. Omit the only children. Classify the other cases as first in birth order, last, " second " (except those also last), " penultimate " (except those also first or second) or " middle " (the remainder). Count the cases in each class. Calculate the number to be expected from the null hypothesis that the cases occur independently of birth order. (The number of cases to be expected in any given place in the table is obtained by dividing the number of cases of that size of sibship by the number in the sibship). For our purpose this classification and procedure appears to be the best of the several similar ones which might be suggested. We obtain these figures:
The null hypothesis can be rejected. In this sample there is of cases which are last in the sibship. There is no " excess of those which are penultimate ", nor of" those which are first. There are relatively few which are second" or " middle ".
an excess
This pattern of distribution does not of course decide between Dr. Slater’s hypothesis that maternal age is the crucial variable and a hypothesis that homosexuality in the male arises out of a distorted relationship with the mother. From the point of view of the latter hypothesis, the pattern observed corresponds reasonably well to what might be suggested if closeness of the relationship with the mother is taken to be a factor in aetiology.