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ERGOMETRY IN THE DIAGNOSIS OF MYASTHENIA GRAVIS
730 the skin can be rapidly located by seeing the skin rise under the magnet and using a non-magnetic probe.
likely in myasthenia gravis, a smaller quantity of is sufficient to compete effectively with it for the postjunctional receptors. On the other hand, magnesium probably acts by still further reducing the amount of acetylcholine released from the nerve-endings. Department of Physiology, D. V. ROBERTS. University of Liverpool.
as seems curare
Medical Department, Esso Refinery,
BARY.
SIR,-Mr. Bridger’s interesting account (Sept. 29) of his experience with a Foley catheter, the balloon of which would not deflate, prompts me to mention a method of achieving deflation of an obstinate balloon rapidly, simply, and in my experience infallibly. 2 ml. of chloroform is injected along the inflation channel of the catheter and the balloon will burst in a few seconds. The only disadvantage is the irritant effect of the chloroform on the vesical mucosa, and it should be washed out vigorously with water or saline before the catheter is removed
SIR,-In August of last year, Dr. Greene and his colleagues1 illustrated, once again, the usefulness of the classical research tool of ergometry. I should like to mention one further application of this technique-the determination of variability in a series of contractions.
By analysing 10 randomly chosen contractions in each subject, I have been able to demonstrate significant differences between successive ergograms in thirty adolescent boys (aged 14 to 16 years) and in thirty-two young adult men (aged 22 to 31 years).2 The non-parametric statistical test of Sidak and
Department of Urology, General Hospital, Newcastle-upon-Tyne.
Vondracek,3 modification of Rosenbaum’s test,4 has been used. The frequency of different ranges of variation in each a
was as
DE
AN UNUSUAL EXPERIENCE WITH A FOLEY CATHETER
ERGOMETRY IN THE DIAGNOSIS OF MYASTHENIA GRAVIS
group
J. L. J.
Fawley, Southampton.
J. SWINNEY.
THE TESTING OF HEAT-SEALED PAPER BAGS FOR AIR-LEAKS
follows: _u-
SiR,—The following tests have been devised to test for air-leaks in the paper bags used by central sterile supply departments for sterile packs:
Institute of
Hygiene, Prague, 10.
1. A completely sealed pack is totally immersed in water, and gently squeezed by hand. A stream of bubbles indicates the presence of air-leaks. Provided this is carried out quickly before the pack becomes waterlogged and begins to disintegrate, it is quite reliable. 2. Some activated-charcoal powder is put inside the paper bag. The bag is then gently inflated with air, and shaken to spread the charcoal powder. The top of the bag is now sealed with tape. If there are any air-leaks a jet of charcoal powder is emitted when the bag is gently squeezed. A piece of clear ’ Cellotape ’ fastened over the site of the air-leak fixes the charcoal powder in position, and a permanent record is obtained. Tests have been carried out on heat-sealed bags, and
JAROSLAV TEJMAR.
A MAGNET FOR OPHTHALMIC AND MINOR SURGICAL USE
SIR,-A small powerful permanent magnet is often useful in ophthalmic and minor surgical work for removing embedded ferrous foreign bodies in the eye and penetrating steel fragments under the skin. A magnet was devised which would be permanent, powerful, small, and not too heavy and the " business end " of which
bags sealed with tape.
The only bags found satisfactory have been those heat-sealed at both ends. Each batch of new bags should be carefully screened before use. Law Hospital, Carluke, Lanarkshire.
A. A. B. MITCHELL.
BLOOD-UREA ESTIMATIONS IN URÆMIA
SIR,-We have noticed that, in severely ureemic patients, serum-urea analyses on the ’Autotechniconby the diacetylmonoxine method1 yield higher results than those obtained by the urease Nesslerisation or hypobromite techniques. On one occasion the discrepancy was as great as 25%. We therefore investigated the further. problem The diacetylmonoxine method is known to give results 2-3% higher than the other two methods,12Marsh al.1 commented that, when serum samples contained more than 80 mg. of urea nitrogen per 100 ml. (170 mg. urea per 100 ml.), " visual inspection indicated that the urease method generally yielded results that were less than those of the carbamido-diacetyl method ", but they did not say whether this difference varied from patient to patient or was ever very great. In our experience the two methods agree well up to serum-urea levels of 100 mg. per 100 ml.; but at higher concentrations the diacetylmonoxine method may give considerably higher results. We have shown that the discrepancy, when present, does not depend on predilution of the serum, differences in standards, or inhibition of the urease by the products of reaction; and it is inherent in the diacetylmonoxine reaction, and not in the operation of the autotechnicon. some
et
would have as small a cross-sectional area as possible. The magnet, made by Mullard Ltd., consists of four cylindrical magnets, end to end, F!t6 in. in diameter (36 mm.) terminated by a ’Permandur polepiece with a rounded end 1/a in. (3 mm.) in radius. This material concentrates magnetic energy, andl in this case concentrates the flux of the four magnets to the tip. The magnet has proved useful. Embedded ocular foreign bodies are removed atraumatically, and steel fragments under ,
,
,
1. Greene, R., Rideout, D. F., Shaw, M. L. Lancet, 1961, ii, 281. 2. Tejmar, J. Unpublished. 3. &Sbreve;idák, Z., Vondráček, J. Applcn. Mathematics, Prague, 1957, 2, 215. 4. Rosenbaum, S. Ann. mat. Statist. 1954, 25, 146.
1.
Marsh, W. H., Fingerhut, B., Kirsch, E. Amer. J. clin. Path. 1957, 28, 681.
2.
Archibald,
R. M.
J. biol. Chem. 1945, 157,
507.
likely in myasthenia gravis, a smaller quantity of is sufficient to compete effectively with it for the postjunctional receptors. On the other hand, magnesium probably acts by still further reducing the amount of acetylcholine released from the nerve-endings. Department of Physiology, D. V. ROBERTS. University of Liverpool.
as seems curare
Medical Department, Esso Refinery,
BARY.
SIR,-Mr. Bridger’s interesting account (Sept. 29) of his experience with a Foley catheter, the balloon of which would not deflate, prompts me to mention a method of achieving deflation of an obstinate balloon rapidly, simply, and in my experience infallibly. 2 ml. of chloroform is injected along the inflation channel of the catheter and the balloon will burst in a few seconds. The only disadvantage is the irritant effect of the chloroform on the vesical mucosa, and it should be washed out vigorously with water or saline before the catheter is removed
SIR,-In August of last year, Dr. Greene and his colleagues1 illustrated, once again, the usefulness of the classical research tool of ergometry. I should like to mention one further application of this technique-the determination of variability in a series of contractions.
By analysing 10 randomly chosen contractions in each subject, I have been able to demonstrate significant differences between successive ergograms in thirty adolescent boys (aged 14 to 16 years) and in thirty-two young adult men (aged 22 to 31 years).2 The non-parametric statistical test of Sidak and
Department of Urology, General Hospital, Newcastle-upon-Tyne.
Vondracek,3 modification of Rosenbaum’s test,4 has been used. The frequency of different ranges of variation in each a
was as
DE
AN UNUSUAL EXPERIENCE WITH A FOLEY CATHETER
ERGOMETRY IN THE DIAGNOSIS OF MYASTHENIA GRAVIS
group
J. L. J.
Fawley, Southampton.
J. SWINNEY.
THE TESTING OF HEAT-SEALED PAPER BAGS FOR AIR-LEAKS
follows: _u-
SiR,—The following tests have been devised to test for air-leaks in the paper bags used by central sterile supply departments for sterile packs:
Institute of
Hygiene, Prague, 10.
1. A completely sealed pack is totally immersed in water, and gently squeezed by hand. A stream of bubbles indicates the presence of air-leaks. Provided this is carried out quickly before the pack becomes waterlogged and begins to disintegrate, it is quite reliable. 2. Some activated-charcoal powder is put inside the paper bag. The bag is then gently inflated with air, and shaken to spread the charcoal powder. The top of the bag is now sealed with tape. If there are any air-leaks a jet of charcoal powder is emitted when the bag is gently squeezed. A piece of clear ’ Cellotape ’ fastened over the site of the air-leak fixes the charcoal powder in position, and a permanent record is obtained. Tests have been carried out on heat-sealed bags, and
JAROSLAV TEJMAR.
A MAGNET FOR OPHTHALMIC AND MINOR SURGICAL USE
SIR,-A small powerful permanent magnet is often useful in ophthalmic and minor surgical work for removing embedded ferrous foreign bodies in the eye and penetrating steel fragments under the skin. A magnet was devised which would be permanent, powerful, small, and not too heavy and the " business end " of which
bags sealed with tape.
The only bags found satisfactory have been those heat-sealed at both ends. Each batch of new bags should be carefully screened before use. Law Hospital, Carluke, Lanarkshire.
A. A. B. MITCHELL.
BLOOD-UREA ESTIMATIONS IN URÆMIA
SIR,-We have noticed that, in severely ureemic patients, serum-urea analyses on the ’Autotechniconby the diacetylmonoxine method1 yield higher results than those obtained by the urease Nesslerisation or hypobromite techniques. On one occasion the discrepancy was as great as 25%. We therefore investigated the further. problem The diacetylmonoxine method is known to give results 2-3% higher than the other two methods,12Marsh al.1 commented that, when serum samples contained more than 80 mg. of urea nitrogen per 100 ml. (170 mg. urea per 100 ml.), " visual inspection indicated that the urease method generally yielded results that were less than those of the carbamido-diacetyl method ", but they did not say whether this difference varied from patient to patient or was ever very great. In our experience the two methods agree well up to serum-urea levels of 100 mg. per 100 ml.; but at higher concentrations the diacetylmonoxine method may give considerably higher results. We have shown that the discrepancy, when present, does not depend on predilution of the serum, differences in standards, or inhibition of the urease by the products of reaction; and it is inherent in the diacetylmonoxine reaction, and not in the operation of the autotechnicon. some
et
would have as small a cross-sectional area as possible. The magnet, made by Mullard Ltd., consists of four cylindrical magnets, end to end, F!t6 in. in diameter (36 mm.) terminated by a ’Permandur polepiece with a rounded end 1/a in. (3 mm.) in radius. This material concentrates magnetic energy, andl in this case concentrates the flux of the four magnets to the tip. The magnet has proved useful. Embedded ocular foreign bodies are removed atraumatically, and steel fragments under ,
,
,
1. Greene, R., Rideout, D. F., Shaw, M. L. Lancet, 1961, ii, 281. 2. Tejmar, J. Unpublished. 3. &Sbreve;idák, Z., Vondráček, J. Applcn. Mathematics, Prague, 1957, 2, 215. 4. Rosenbaum, S. Ann. mat. Statist. 1954, 25, 146.
1.
Marsh, W. H., Fingerhut, B., Kirsch, E. Amer. J. clin. Path. 1957, 28, 681.
2.
Archibald,
R. M.
J. biol. Chem. 1945, 157,
507.