The mucoproteins of the eye lens

612

SHORT

COMMUNICATIONS

I would like to express my thanks to Dr. S. M. WEIUMANN

for helpful advice and

criticism and to Mr. B. WRAY for technical assistance. The work was carried out with the assistance of a grant from the Medical Research Council of Great Britain. Biological

Research

LTnit,

J. A. WEATHERELL

School oj Dentistry,

Lrwiversity

of Leeds

(Great Britain)

1 H. D. APPLIXO.\T,.\I. \VEST, M. RIANDEL ANU .-\. M. SALA, Clip. C/w%, 5 (1959) 30 6 I>.N. BARON AND J. I_ BELL, J. CZi+z.Pathol., IL (1959) 143. 3 I'.CARTER ANL) J. CLEMEXT-METRAL, Cli~a.Chinz. .4cta, 4 (1959) 357. 4 I<.CARUBELLI, \V. 0. S~XITH ANL) J, I;.HARIMARSTEN, Clip?.Chewz., 5 (1959) 45. 5 H. 1'.MALMSTADT AND T. I'.HAUJIIOANXOU, Cli~z.Chew., 5 (1959) 50. 6 K. bIOR1, .4vch.Biochem. Biophys., 83 (1959) 552. i I<. L’. I
Received

March rgth,

1960

The mucoproteins

of the eye lens

BELLOWS' has suggested that mucoprotein acts as a cement which holds the individual fibers of the bovine eye lens loosely together. Kr~us~~deduced the presence

of mucoproteins in the bovine lens by precipitating the lens proteins with acetic acid and determining the nitrogen distribution of the various layers of the lens. PERMUTT~ confirmed this by a histochemical method in which the lens polysaccharides were stained. We have examined the mucoproteins in the individual human lens and have tried

to find a correlation

between

the mucoprotein

appearance of its transparency. We have used the polarographic

content

method because

of the lens and the clinical

of its great sensitivity.

Accord-

ing to WINZLER~ and KALOUS~ the mucoproteins which pass into the sulphosalicylic acid filtrate are responsible for the polarographic activity of the filtrate. Although in the case of blood serum other polarographically active agents interfere6, it is possible to determine the differences of the mucoprotein content by this method. The intracapsullary extracted lenses were dried, weighed and homogenized in 3 ml of distilled water; I ml of the homogenate was denatured for 45 min with I ml of 0.1 N NaOH. The sample was then deproteinized with I ml of a zoq, sulphosalicylic acid solution and 0.5 ml of the sulphosalicylic acid filtrate was examined polarographically in I ml of the classical ~~KL)ICKA'~' solution. We examined IO clear lenses (extracted within 3 h post mortem) and 12 cataract lenses (after intracapsular extraction of seuile cataracts). The average height of the polarographic wave under experimental conditions was 81 3: 13 mm (calculated for a weight of I g of the normal lens) while the average height of the wave for cataract lenses was 127 & zq mm/g. The difference is significant even for P
LE~VINA~ and K&ENT@ showed that the polarographic activity of mucoproteins alone does not increase under the influence of alkali. Similarly, the lens homogenates of clear and also of cataract lenses do not show any increase in their polarographic activity under the influence of alkali. Thus it is probable that the cataract changes in the lens are accompanied by an increase in the mucoproteins; perhaps a compensatory mechanism is involved. We should like to mention another fact which is probably related to changes in the lens proteins: the pH of the cataract lens homogenates is significantly higher than that of the clear lensesB. The increase follo~~sprecisely the progress of the lens opacity. This phenon~cnoll will be discussed later9 together with a more particular evaluation of the mucoprotcin findings. l’ke Eye Clinic Oncological

of the L’niversity

Institute,

Bmo

of Brno

(Czechoslovakia)

and the

31. MOSTER J. PREISOV.~ A. KOCE~VT

JieceiVed ApriI znd, 1960

A note on the haemoglobin error in some non-precipitation diazo-methods for bilirubin determinations The purpose of this communicatiorl is to indicate the estent to which bilir~lbin assays can be considered rehable when performed on sera showing trace (invisible), slight and gross haemolysis. Statements about the influence of hacmoglobin on different methods for bilirubin estimation ha\ve usually been based on r’ery limited studies. L.-\URENCE AND ABBOTT using their own modification of the MALLOY-EVELYN~ procedure examined the effect of adding I to 7 g”/; haemoglobin to a serum containing 3.4 mg bilirubin/Ioo ml. They considered that at low levels of bilirubin even I’+~ Hb might completely invalidate the result, while at high levels analyses were unlikely to be significantly affected by less than 3:/i, Hb”. WIrrrR et aI. examined 6 sera to which they added o.zjy$ Hb. A loss of from 9 to jo(;i, of azo-pigment production occurred dhen the MALLOWESELYPZ method with a rg-min reading was employed. Using another modi~~atioI1 of the X*LIOYEVELYN procedure a serum containing 17.8 mg bilirubin/roo, ml was found by