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Discussion

The peroxydatic activity of haemoglobin in the pres-ence of hydrogen peroxide catalyses the oxidation ofTMB to a coloured product. Haemoglobin peroxi-dase has been termed a 'pseudoperoxidase'7 because,unlike true peroxidases which exhibit specificity forphenols, erythrocytes contain a peroxidase (ery-throcyte glutathione peroxidase) specific for oxida-tion of reduced glutathione. This causes the in vitrodetoxification of hydrogen peroxide. Glutathioneperoxidase activity has been found to be associatedwith a relatively stable, nondialysible, heat-labile,intracellular component which can be separated fromhaemoglobin by gel filtration and ammonium sul-phate precipitation. The pH optimum of glutathioneperoxidase has been shown to be pH 8-0 with negli-gible activities below pH 6.0.8 Pretreatment of thefixed slides with resorcinol before staining with TMBand hydrogen peroxide inhibits myeloperoxidasestaining. This increases specificity of the stain and re-duces error in enumeration of erythroid colonies. Byomitting counter staining only erythroid colonies andprecursors are stained.

This work has been supported by the PathologyDevelopment Foundation, Trinity College, Dublin.

References

Garner C. Testing of some benzidine analogues for micro-somal activation to bacterial mutagens. Cancer Lett 1975;1:39-42.

2 Holland VR, Saunders BC, Rose FL, Walpole AL. A safersubstitute for benzidine in the detection of blood. Tetra-hedron 1974;30:3299-302.

Broyles RH, Pack BM, Berger S, Dorn AR. Quantificationof small amounts of hemoglobin in polyacrylamide gelswith benzidine. Anal Bioclhem 1979;94:211-9.

4Garner DD, Cano KM, Peimer RS, Yeshion TE. An evalu-ation of tetramethylbenzidine as a presumptive test forblood. J Forensic Sci 1976;21:816-21.

Stephenson JR, Axelrad AA, McLeod DL, Shreeve MM.Induction of colonies of hemoglobin-synthesizing cells byerythropoietin in vitro. Proc Natl Acad Sci USA 1971 ;68:1542-6.

6 McLeod DL, Shreeve MA, Axelrad AA. Improved plasmaculture system for production of erythrocytic colonies invitro: Quantitative assay method for CFU-E. Blood 1974;44:517-34.

7Gomori G. In Microscopic histochelnistry. University ofChicago Press, 1952:162-5.

Paglia DF, Valentine WS. Studies on the quantitative andqualitative characterisation of erythrocyte glutathioneperoxidase. J Lab Clin Med 1967;70:158-69.

Requests for reprints to: Dr SR McCann, Department ofClinical Haematology, Trinity Medical School Building,St James's Hospital, Dublin 8.

An automated method forrecording the Westergrenerythrocyte sedimentation rate

JF KING,* K KENNEDY,* AND AR RIMMERt *Depart-ment of Haematology, Ninewells Hospital, Dundee,and tthe Tayside Regional Physics Department

An automated system for recording the Westergrenerythrocyte sedimentation rate (ESR) is described.The method was developed to cater for the fre-quently occurring but small numbers of late speci-mens which otherwise delay staff after normalworking hours.

Principle

The method involves photography of the ESR testsexactly I hour after being set up, in such a way thatthe photographs are easily and rapidly obtainablewhen required and the results can be easily read.

Equipment

A Polaroid MP-4 camera with Tominon f4-5, 135 mmlens and Copal shutter is used. This camera employsbellows focusing so that close-up work is easilypossible.A base was constructed to hold the camera and

ESR rack at a fixed distance apart, which givesoptimum framing of the rack on the film. This baseis made mainly of perspex and wood. The circularcamera base is held in place by and can rotate in aperspex ring. Using a focusing screen, the camerawas aligned as required; then a line was engraved onthe camera base and perspex ring. The focus wasalso marked on the bellows guides, and in this waythe camera can be set up rapidly without having tore-align or refocus each time (Fig. 1). The film usedis Polaroid Land Type 107C. This is a black-and-white film rated at 3000 ASA (36 Din).The timing device consists of a shutter-activating

system, which uses a simple mains-driven timer(ORMON-Type STPNH, 72 min) which switches onan electric motor after a pre-set time. The motor hasa large reduction gear box which gives a shaftspeed of 1 revolution per minute. This gives ade-quate torque from a low-power motor to drive a camwhich activates the camera shutter.The electrical control circuit is simple and as

foolproof as possible. There are two parts to it: oneis the setting up procedure, and the second is thetimer and motor operation.Accepted for publication 5 November 1980

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Fig. 1 Geiieral view of equipment.

Fig. 2 Circuit diagram.Camera remote shutter- ,elease.

With the mains switched on the indicator neon isilluminated. The reset button is pressed by the oper-ator, and the motor starts and drives the cam arounduntil a microswitch is operated. This action closesthe contact on the microswitch, and the timer isactivated. The timer neon is now on and the resetbutton can be released.

After the pre-set time (1 hour in our case) thetimer contacts close, the motor is switched on, andthe cam rotates and operates the camera shutter. Asthe cam rotates further the microswitch is operatedand switches off the timer. The circuit is nowdisabled with only the indicator neon operativeuntil the operator resets the cycle. It is imperative to

keep the friction on the cam as small as possible toreduce the risk of malfunction. A circuit diagram isshown in Figure 2.The ESR equipment used is as supplied by

Accu-Tech Ltd. Modifications were made to therack in order to record, on film, the time at whichthe tests are set up and the time at which the photo-graph is taken (this interval of time being 1 hour).Inset into the lower part of the ESR rack are four 0-9thumbwheel switches which can be manually set torepresent the time at which the tests were set up.Above the thumbwheel switches is inset a Citizenquartz analogue watch which will indicate the timeat which the photograph was taken. This watch was

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Fig. 3 Polaroidphotographof set of tests.

selected for the clarity of the figures and hands. It willoperate continuously for approximately one yearbefore battery replacement is required (Fig. 3).

LIGHTING FOR PHOTOGRAPHYThe very sensitive emulsion of the film makesphotography possible in artificial light. However,whether natural or artificial light is used, it isessential that even and constant illumination falls onthe rack. We have found that the standard fluores-cent lighting in the laboratory is perfectly adequatefor a satisfactory photograph with the camera set atf5-6 and 1/60th second exposure.

Test procedure

Blood samples for ESR tests which arrive at thelaboratory during the last working hour of the dayare set up as a batch just before the staff leave. Usingthe Accu-Tech suction pump, stand, and tubes, it willtake no more than 30 seconds to set up all the tests,and all other aspects of the test are as recommendedin the recent ACP Broadsheet.1 Immediately thetests have been set up, the timer is activated. Thethumbwheel switches are set, and the camera settingsare checked. These should include camera alignment,focus, and exposure settings. The photograph istaken after 1 hour and the exposed film remains inthe camera until it is convenient to develop it,

usually the next morning. At this time the exposure isremoved from the camera and developed accordingto instructions supplied with the film. This willgenerally take less than 1 minute. After confirmingfrom the photograph that the exposure has takenplace at 1 hour, the tests are read. It is useful toarrange the framing of the photograph in such a waythat the specimen numbers appear within thephotograph (Fig. 3).The use of a camera and watch in the laboratory,

especially after working hours, may present asecurity problem. In the equipment described, thishas been minimised by locking the camera to thebase. The watch is attached to the rack by means ofa metal block screwed securely in place.The cost of film is £2-48, and with eight exposures

each photograph costs 31p. The rack may containfrom one to 10 tests so that the individual cost of thetests is between 31p and 3-1p. It can be seen thatrunning costs are considerably less than the paymentof staff who might be required to stay after hours.The capital cost of the equipment to this department,including camera, watch, rack, base, and timer wasabout £260.The above equipment has been in use in this labora-

tory for some months and has proved reliable as wellas providing a convenient way of dealing with theselate and time-consuming tests. It may also be of use attimes throughout the nQrmal working day.

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We thank the staff of the Regional Physics Depart-ment for their skilled assistance and co-operation,Dr HB Goodall for his help with the script, and MrRS Fawkes for Figure 1.

Lewis SM. Erythrocyte sedimentationi rate and plasmaviscosity. ACP Broadsheet 94, 1980.

Requests for reprints to: Mr JF King, HaematologyDepartment, Ninewells Hospital, Ninewells, DundeeDDI 9SY.

Letter to the Editor Book reviewsUCH microbiology computer system

After the meeting of the Association ofClinical Pathologists at Reading in 1979,at which Dr Ridgway described the dataprocessing system he and his colleaguessubsequently described in the Journal,'negotiations were started between SellyOak Hospital and University CollegeHospital to transfer the software to themicrobiology department at Selly Oak.The transfer has now been completed

and the system has been operating atSelly Oak for about three months. Most ofthe delay was in getting the necessary

finance and in having extra wiring put in,so that the interval implied between spring1979 and autumn 1980 could have beenmuch less.The UCH microbiology software has

been implemented at SOH on a DEC 11/34processor with 64K words of memory anddual RLO1 (5 Mbyte) disks. Five visualdisplay units, a label printer, and a charac-ter printer complete the hardware neces-

sary for routine operation. As part of theagreement with the West Midlands Re-gional Health Authority, who funded thescheme, an additional RLOI disk driveand two modems and GPO lines were alsoinstalled to permit shared access by up tofive other microbiology laboratories with-in the Region. User laboratories do notshare the UCH laboratory system in a

routine sense but make use of subsets of itand other purpose-written programs forlimited routine and ad hoc data processingfunctions.About the only modification to the

UCH software that was required for theSelly Oak users was to alter the hospitals,wards, and staff codes, and we changed thespecimen code from a numeric to an alpha-numeric one. These modifications to theMUMPS program were completed literallywithin a few hours. We were given thesalary of a programmer for one year andhad a haematology technician with an in-terest in computers seconded to us from

another local hospital for this. He madeseveral journeys to London to discuss theproject with Mr Batchelor of UCH andthen tackled the problems of writing pro-grams based on the UCH system for the'bureau' users, each of whom has his ownparticular requirements.As far as the staff at SOH is concerned,

two members of the technical staff took aparticular interest in the scheme before itwas installed and were able to help theothers to 'get to know the ropes'. We hada fortnight after the hardware and soft-ware had been installed to get au fait withentering data before putting the work ofthe whole department on the system on1 July 1980.Although it would be easy to revert to

our old system of processing reportsshould a major breakdown occur, we de-cided not to run the two systems in paral-lel, and the 'into the deep end' approachhas worked.

Ultimately, the SOH users will requirenew programs to be written to cover thestatistics that we wish to recover, whichare different from those extracted by UCH,but the workings of the two departmentsare so similar that we have not yet foundany major problems.We were pleasantly surprised at the

smoothness of the transfer but are veryconscious of the effort made on our behalfby Mr Batchelor of UCH and members ofthe staff of the Wolfson Research Labora-tories at the Queen Elizabeth Hospital,Birmingham, who have acted as advisersand are still giving us support.

ISLA CRAIGSelly Oak Hospital,Raddlebarn Road,

Selly Oak, Birmingh7am B29 6JD

Reference

Ridgway GL, Batchelor J, Luton A,Barnicoat M. Data processing in micro-biology: an integrated simplified system.J Clin Pathol 1980;33:744-9.

Contributions to Nephrology. Vol 23.Pathophysiology of Renal Disease. EdsE Ritz, SG Massry, A Heidland andCK Schaefer. (Pp vi + 234; illustrated,US$58.75.) Karger. 1980.

This seminar issue incorporates a seriesof recent reviews on renal and allied topicsof physiological and clinicopathologicalinterest. Authorship is shared by NortlhAmerica and Europe. Physiological em-phasis falls on the renal handling ofcalcium and phosphate; clinically orient-ated topics focus attention on the renalcomponent of the hepatorenal syndrome,the haemolytic uraemic syndrome, renalfunction and electrolyte disturbance inmalignant disease, and the obscurities ofoedema of idiopathic, nephritic, andnephrotic types. There are helpful con-tributions on the management of thenephrotic syndrome and the controversialtopic of interstitial nephritis. There arefive papers devoted to essential hyperten-sion with interest centred on the kallikrein-kinin system, peptidergic and cate-cholaminergic mechanisms, renal prostag-landins and the role of the sympatheticnervous system. Hypertension in preg-nancy, its pathogenesis and management,with particular emphasis on the pre-eclamptic state, are considered separately.

This volume illustrates the benefits andlimitations of reviewing major, oftencontroversial, topics in seminar form.While providing a useful platform fornew ideas and interpretations, literaryreview is of necessity restricted and recent.Structural morphology contributes littleto this publication. Nonetheless, patholo-gists, particularly of the renal variety, incommon with their clinical and pre-clinical colleagues, will discover new andpertinent information in these presenta-tions.

G WILI-IAMS

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