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to excrete viruses, so to speak of prolonged or persistentsurvival of virus has little if any meaning. There is noevidence whether the persistence of intralymphocytic virusfor from 24 to 196 days 9 represents prolonged survival ornot. Whatever the case, the duration of infection is largelydetermined by the lifespan of the infected cell, and is onlysecondarily influenced by immunological mechanisms.

If Not Immunological Tolerance, Why Not? ?If specific cellular immune deficiency is neither a cause,

nor even an inevitable concomitant, of chronic viral in-fection, then why is it that tolerance does not arise whenvirus in released from dying cells before and during thedevelopment of the immune system ? In experimentalanimals it has been shown that the likelihood of toleranceinduction on exposure to antigen is greatest during thisperiod. The observation that most babies with congenitalrubella have adequate humoral responses is evidence thatthey do not have complete immunological tolerance to thevirus. This in turn implies that at least some cells, such asthe precursors of those that produce anti-rubella antibody,are not infected, assuming that virus is unlikely to

coexist with a cell producing antibody against it. Having

deduced that there are differences in cell susceptibilitywe cannot now offer this deduction as an explanationof the absence of partial or complete immunological toler-ance, even though our ignorance of the mechanisms bywhich tolerance is induced is such that there is a greattendency to do so. Thus the question remains unsolved,although from the foregoing it seems likely that cell

sequestration and intracellular residence of virus are fac-tors of major importance. It is conceivable that, althoughendocytosis occurs at all stages of foetal development, inthe immunologically incompetent phase of foetal life thisis not followed by the later stages of the immune-inductionprocess. When competence develops the dissociation ofphagocytosis and the immune response is overcome andspecific cellular immunity with production of antibodyresults.

I was greatly assisted in developing this hypothesis by discussionswith Dr. Nigel J. Gray, Dr. Robert Fowler, and Mr. Ian Jack. I amindebted to Miss Margaret Fitzgerald for drawing the figures. Thework was supported by a grant from the National Health and MedicalResearch Council of Australia.

M. J. SIMONSM.B. N.Z.

Royal Children’s HospitalResearch Foundation,Melbourne, Australia

Methods and Devices

BONE AND MARROW BIOPSY WITH

SAW-TOOTHED MODIFICATION OF

VIM-SILVERMAN NEEDLE

METHODS for obtaining bone and marrow biopsy specimenshave included open surgical excision and the use of theVim-Silverman needle, with its original blades 2 or modifiedblades,3 or of large-bore serrated trephines.4 5 We describehere the fabrication and use of a trephine needle which has beenfound to provide easily and consistently, with insignificanttrauma and discomfort to the patient, an adequate specimen oftissue. It can be made readily from discarded Vim-Silvermanneedle parts.Fabrication

Most hospitals have a quantity of discarded 16-gaugeVim-Silverman needles with damaged blades. From these partsare selected one cannula and two obturators; the blades are not

1. Weisberger, A. S. Am. J. med. Sci. 1955, 229, 63.2. McFarland, W., Dameshek, W. J. Am. med. Ass. 1958, 166, 1464.3. Conrad, M. E., Crosby, W. H. J. Lab. clin. Med. 1961, 57, 642.4. Hocking, D. R. Med. J. Aust. 1964, ii, 915.5. Sacker, L. S., Nordin, B. E. C. Lancet, 1954, i, 347.

Fig. 1-Fabrication of saw-toothed cutting cannula(A or B), periosteum-penetrating obturator (C),and extruding obturator (D).

Fig. 2-Relative lengths of thethree parts.

used. Into the end of the cannula are cut saw teeth. The

physician himself may cut two or three crude notches witha small triangular file (fig. 1A), or three or four teeth may becut with precision by a machinist (fig. 1B). One obturator isthen sharpened to protrude approximately 2 mm. past the sawteeth (fig. 1C); this is used to penetrate the periosteum. Thesecond obturator is filed off bluntly and left long enough toprotrude past the saw teeth (fig. 1D); this is used to expel thebone and marrow specimen from the cannula. The finished setis thus composed of three parts (fig. 2). Our first such instru-ment was filed into form over the edge of a desk and still worksvery well.

TechniqueWith this needle the anterior or posterior iliac crests are

usually chosen for biopsy of cortical and cancellous bone. First,the bony landmarks are carefully palpated. After lavage withsoap and water, the skin is prepared with an antiseptic; steriledrapes and gloves are used. With a 25-gauge needle, a skinweal is made with a local anxsthetic. Through this weal alonger needle is inserted to infiltrate the periosteum with theanaesthetic. Then, with a sharp pointed (no. 11) blade, a nick

is made through the skin of the weal to allowfree passage of the biopsy needle. With the

sharp obturator in place, the saw-toothedcannula is grasped in one hand with the buttagainst the palm and the shaft held firmlybetween index finger and thumb. When the

periosteum has been penetrated about 2 mm.,the sharp obturator is withdrawn and the saw-toothed cannula is advanced in consecutivecorkscrew turns toward an imaginary stationarypoint that is not in line with vital structures-e.g., if the anterior or posterior iliac crest is used,the needle is directed laterally, away from theabdominal cavity. Once the periosteum has beenpenetrated, little pressure is required; andcontrol is enhanced by using more torque thanforward thrust. When the usually desired depthof 1-11/2 cm. has been reached, the saw-toothedcannula is simply pulled out as the bone andmarrow remain snugly within the lumen. Theblunt obturator is then used to push the biopsyspecimen from the lumen. The specimen is

gently lifted into 10°n formalin for fixationbefore decalcification and histological sectioning.Touch specimens or cultures may be taken.We have encountered no difficulty with bleeding,

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but apply pressure to the biopsy site for ten minutes as aprecautionary measure. There have been no post-biopsycomplications. Repeated biopsies are possible with this nearlypainless and relatively atraumatic procedure.Results

Diseases in which we have used this needle and techniquehave included granulocytic leukxmia, lymphocytic leukxmia,myelofibrosis, osteitis fibrosa cystica in a case of primaryhyperparathyroidism, secondary hyperparathyroidism of renaldisease, sarcoid, miliary tuberculosis, carcinomatosis, and focallytic metastatic carcinoma. The needle has provided adequatetissue without the disadvantages associated with large-boretrephines or surgical excision with curettage. It is, in our

experience, more reliable than the Vim-Silverman method andprovides a specimen of greater diameter than the latter sincethe blades within the cannula are not used.

Requests for reprints should be addressed to G. C. M., Depart-ment of Medicine, U.S. Army Hospital Specialized TreatmentCenter, Fort Gordon, Georgia 30905, U.S.A.

GORDON C. MILLERM.D. Georgia

DAVID T. DENNISM.D. Cornell

Department of Internal Medicine,Tulane Medical School, andCharity Hospital of Louisiana,New Orleans, Louisiana

FORWARD-ACTION FORCEPS

WHEN a vessel or similar structure can be mobilised suffi-ciently to be twisted round and grasped by the conventionallycurved forceps, little difficulty is experienced in clamping,cutting, and tying it. But if mobilisation is difficult or impos-sible, or the structure to be dealt with is backed by a flat sur-face, such as the posterior abdominal wall, attempts to catch itsecurely in a clamp, and ligate it safely after section, can beprolonged and irritating. Difficulty can, for example, be experi-enced with the cystic duct and artery, the vagi, or the lateralpedicles of the rectum or uterus.For the past nine months I have been using forceps which

have proved successful in overcoming this difficulty (see figure).The curve of the jaws is in the same plane as the long axis of

the shaft, instead of being at right angles as in the usual design.With this instrument it is extremely easy to slip the distal jawunder the vessel or pedicle, clamp and cut it, without anytwisting.Two sizes have been found sufficient, as they have only been

used for abdominal work so far. The smaller size has been

particularly useful in the upper abdomen, and the larger in thelower abdomen and pelvis. A gynaecological colleague has foundthem of great value in dealing with the uterine artery in vaginalhysterectomy. I have not had the opportunity of testing themin thoracic work.These forward-action forceps are available either with curved

jaws, or with right-angled jaws (as illustrated) where a sub-stantial pedicle is involved.

I thank Mr. Geoffrey Down, of Messrs. Down Bros. and Mayer& Phelps Ltd., from whom these instruments can be obtained, forvaluable help in their design.

H. H. BARSTF.R.C.S.

General Hospital,Dewsbury, Yorkshire

Reviews of Books

Labor

Clinical Evaluation and Management. EMANUEL A. FRIEDMAN,M.D., professor of obstetrics and gynaecology, Chicago MedicalSchool. London: Butterworth. New York: Meredith PublishingCo. 1968. Pp. 397. E5 12s. 6d.; $13.50.

ALMOST every woman, once securely established in labour,will ask her attendants when her baby will be born. Facedwith this question, both midwives and doctors are eitherreticent or vague. Although this uncertainty reflects thetraditional view that any forecasts should be avoided (in casethey are proved wrong), there is also a lack of suitableevidence upon which any accurate prediction might be based.By describing the patterns of cervical dilatation in a largenumber of women, Professor Friedman’s book goes some waytowards supplying this evidence. The method is simple:cervical dilatation recorded (in centimetres) at vaginalexamination is plotted against time on linear graph-paper.Professor Friedman divides the first stage of labour into anumber of distinct phases. In the first, and largest, of thesethe os dilates slowly to about 3 cm. Labour then enters anactive phase when dilatation becomes much more rapid, onlyslowing down in the brief deceleration phase just before thesecond stage. Although many would argue about the exactshape of the cervical dilatation graph, and although variousphases are less easy to define than Friedman suggests, thedifferences are small and, in terms of practical management,unimportant. There are, however, minor discrepanciesbetween the data given in detail and the consolidated graphs ofcervical dilatation. For example, the graphs which have nowbeen sanctified by reproduction in many standard textbooksshow the cervix to be closed at the onset of labour. Obstetri-cians know that this is seldom so, and indeed Friedman’sfigures cited elsewhere in the book show that in 80% of

nulliparx and 95% of multiparse the cervix is at least 1 cm.dilated when the labour starts. Nevertheless this book con-tains an enormous amount of carefully documented quantita-tive information bearing on the pattern of normal labour andthe effect of a host of factors such as malpresentation, maternalage, parity, height, and anxsthesia. The author’s maincontribution lies, however, not in the detail but in hisdemonstration of the general value and simplicity of a

graphical representation of labour. There is no better way toinstruct medical students in the assessment of labour than forthem to prepare graphs of cervical dilatation in a dozen or socases. Widespread adoption of the method would allowmidwives and doctors to answer their patients’ queries aboutthe duration of labour, unashamedly and with a tolerable

degree of accuracy.

Electrolyte Metabolism in Severe Infantile MalnutritionJ. S. GARROW, M.D., PH.D., M.R.C.P.E., Medical Research Councilstaff, department of obstetrics, Royal Free Hospital, LiverpoolRoad, London N.1; ROGER SMITH, M.A., M.D., M.R.C.P., seniorWellcome Research Fellow, medical unit, University CollegeHospital, London W.C.1; E. EUGENE WARD, M.D., lecturer,department of physiology, University of the West Indies,Jamaica. Oxford: Pergamon Press. 1968. Pp. 168. 67s. 6d.

SINCE the classical work of Kerpel Fronius, Gamble, andDarrow in the late 1920s and 1930s, the metabolism of electro-lytes has been an integral part of pxdiatrics. Disturbances in

electrolyte metabolism were frequently provoked in those daysby gastroenteritis and, since gastroenteritis commonly accom-panies, and may cause, the malnutrition for which childrenare brought to hospital in many parts of the world today, theauthors of this book were fully justified in making a special studyof the relationship in such infants. They have done us alla signal service. The objectives of the book are clearly set outon page 2. Essentially these are physiological and therapeuticstudies, backed by many references to the world literature, ofabout 700 infants admitted to the university hospital and themalnutrition unit of the Medical Research Council in Jamaica.