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In conclusion, Dr. SIMMONDS said that the risks to thebaby could be combated by removal to a suitable environ-ment, by routine examination including Mantoux testing,by treatment to make the mother’s infection quiescentduring pregnancy, by wearing masks during the handlingof the baby and such elementary precautions as the useof separate crockery, and by breast-feeding only inarrested or recovered cases ; they hoped for great thingsfrom B.C.G. vaccination in this priority class. General

practitioners and infant-welfare clinics could rely uponchest physicians to assist them in advising individualpatients for or against pregnancy.Recent Developments in InfluenzaThe meeting ended with a paper from Dr. C. H.

ANDBEWES, F.R.S., designed to show that the laboratorydetection of the influenza virus by haemagglutination orcomplement fixation was necessary in order to under-stand how the condition spread over the world. TheWorld Health Organisation had recently establisheda world influenza centre at Hampstead. The 1948-49outbreak of virus-A influenza began among shepherdsisolated in the country districts of Sardinia, and spreadvia Sicily and Calabria, up Italy, through Austria, toSwitzerland, France, and Spain, and thence to Belgium,Holland, western Germany, England, Scotland, Ireland,Copenhagen, and Iceland. It might be significant thatin the previous spring Sardinia had been subject tooutbreaks due to B virus, which, having seeded, hadgone undergound to reappear in the autumn. An interest-ing recent development was the detection of filaments,seen by dark-ground illumination, in virus adsorbed on tothe surface of red cells. This was independent of theelectron microscope and might alter the whole concept tof virus structure.

Behaviour Difficulties in Childreit were discussed jointly.with the section of child health (see above).

ANATOMY AND PHYSIOLOGY

President : Prof. JOHN KIRK

Muscle Structure and FunctionProf. W. T. ASTBURY, r.R.s., opening a symposium held

by the section of anatomy, developed the theme of muscleas a molecular machine. The contraction of muscle isregarded as the concertina-like closing-up of its consti-tuent myosin molecules-long polypeptide chains orientedalong the length of the muscle-fibre. In skeletal muscleat least, a second protein, actin, is closely associated withthe fundamental contractile molecule, myosin. This

actomyosin complex does its work in an environment ofaccessory molecules which provide, as it were, the fueland lubricant of the machine. These auxiliaries-

adenosine-triphosphate, calcium, potassium, and so on-are now known to be concentrated at regular intervalsalong the length of the skeletal muscle-fibre, and areresponsible for the transverse striations. Folded moleculesform the thread from which other tissues of the animalfabric are woven. The master-plan is seen in the keratinmolecules of the epidermis and the fibrinogen of blood-clot. The motile flagella of some bacteria are probablyto be thought of as monomolecular muscles.

Dr. R. BARER spoke of his work on the sarcolemma.At the limit of resolution of the electron microscope thisappears optically structureless, but studded irregularlywith tiny excrescences. At present one cannot even guesstheir nature. How does the muscle-fibre exert a pull onits tendon The fibres of muscle and tendon are probablydiscontinuous, the end of the muscle-fibre being clothedwith a cap-like investment of sarcolemma. It may bethat the pull of the fibre is transferred to the sarcolemmaby frictional forces between the two.That muscle will undergo necrosis if its blood-supply

is interfered with is of course well known. Prof. W. E.LE GROS CLARK, F.R.S., reviewed his work which has

demonstrated that in rabbits the blood-supply of skeletalmuscles is of a regional character, occlusion of one of the

smaller intramuscular branches of the supplying arteryproducing a circumscribed area of muscle necrosis. Thiswork is clearly of importance to the orthopaedic surgeon,who must now learn more of the pattern of intramuscularblood-vessels if he would minimise destruction in muscleswhich he may have to incise in approaching deep strue-tures in the limbs. While it is true that small necroticareas of muscle may be quite dramatically repairedby regenerative growth from persisting normal fibres

surrounding the devascularised area, such regenerationis not enough to produce significant results in areas

of gross destruction. Fibrous repair, with attendantfunctional loss, must then take place.

Muscle is equally dependent for its integrity upon itsnerve-supply. Dr. R. E. M. BOWDEN presented theresults of her studies on the changes in human musclefollowing peripheral nerve lesions. Progressive, thoughunequal, atrophy of muscle-fibres, proliferation of inter.stitial connective-tissue, thickening of the walls of smallintramuscular blood-vessels-all now well known in

experimental animal material-occur similarly in man.Muscle end-plates and the empty Schwann tubes leading Z5

to them may be recognised for as long as nine monthsafter denervation, but after this time reinnervationbecomes progressively less satisfactory. The disappear-ance of end-plates, the obliterating fibrosis of Schwanntubes, the atrophy and disappearance of muscle-fibres,the reduction of the vascular bed, and the stranglingfibrosis of the whole muscle all contribute to the failureof late reinnervation.Mr. W. F. FLOYD discussed the contribution of electro-

myography to the study of muscle activity. As a toolin the study of the group action of muscles, the electro-myograph may lead the anatomist to revise some

long-cherished misconceptions.Oont1’ol of Activity in the Gastro-ititestiiial Tract,In the section of physiology Prof. R. A. GREGORY

opened the proceedings by describing the results of hisrecent investigations into the control of tone and motilityin the small intestine in relation to meals, using isolatedsegments of jejunum in trained unanaesthetised dogs.The results indicate that after meals there are changes intone and motility which retard the flow of fluid throughsuch loops. The effects are due to nervous reflexes of:(a) extrinsic origin, as shown by the occurrence of suchchanges on sham feeding, on distension of the stomach,or with the presence of food in other parts of the smallintestine ; and (b) intrinsic origin in the form of localreflexes excited by osmotic pressure, acidity, and otherchemical factors in the contents of the intestine.

Dr. J. N. HUNT described some recent observations,at Guy’s Hospital, on the emptying pattern of thestomach, made by means of serial test-meals. A standardmeal is repeatedly given to one subject on successive

days, the time of complete withdrawal being progressivelylater on each day. In 21 subjects given a standard pectintest-meal, the emptying of the stomach was found to beregular from day to day in the same subject, with all

unexpectedly small variation between subjects. The rateof emptying was proportional to the volume of the gastriccontents. A mean of about 3% of the gastric contents leftthe stomach per minute.

Dr. A. A. HARPER summarised the established factsabout the control of the secretions of the pancreas, withpassing reference to the stomach. He pointed out thatthe increased output of enzymes after a meal, which isfound even in an animal with an extrinsically denervatedpancreas, suggests the existence of some local mechanismfor the stimulation of enzyme production. This is evi-dently not the result of secretin stimulation, for thishormone produces no outpouring of enzymes. In col-laboration with Prof. H. S. Raper, F.R.S., he has

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discovered that a protein-like substance-christenedpancreozymin-extracted from the small intestine doesin fact stimulate the production of enzymes withoutincreasing the flow of alkaline fluid. In man this substancehas been found to stimulate the production of enzymesfrom the pancreas with the simultaneous discharge ofthe contents of the gall-bladder, possibly due to contami-nation by cholecystokinin. Some preparations from theintestine and the antrum increase the output of enzymesand acid from the stomach, as distinct from preparationsof gastrin which increase only the output of acid. How-ever the stimulation of enzyme output from the stomachis not sufficiently regular for a confident opinion thatpepsin production is under hormonal control.

Dr. C. E. DAViES revealed in simple language some ofthe biochemistry of the acid-producing cells of the gastricmucosa, based on researches on isolated stomachs from

frogs and small mammals. In experiments performed atSheffield, studies by direct observation under the micro-scope have shown that the acid is secreted by the cells ;no precursor is produced. Most, and perhaps all, of thehydrogen ions come initially from the hydrogen atoms ofwater, and an equal number of carbon-dioxide moleculesare hydrated within the oxyntic cells under the influenceof carbonic anhydrase. This prevents accumulation ofhydroxide ions within the cells, since they are neutralisedand the bicarbonate ions formed are exchanged acrossthe cell-wall for’ chloride ions. Many hydrogen ions(probably up to eleven) can be secreted for the metabolicproduction of one carbon-dioxide molecule by the oxynticcells, so most of the carbon dioxide required must diffuseinto the cells from the blood. In the absence of adequatesupplies of carbon dioxide from the surrounding fluids,isolated frog gastric mucosa has been found to ulcerate- point which may perhaps have clinical bearing. Thestomach has a maintained potential difference across itswalls and can act as a source of electric power. If thenatural potential is enhanced or opposed by powersupplied from an external battery, the rate of acidsecretion can be increased or decreased. The formationof hydrochloric acid is an electrochemical processand similar mechanisms apparently occur during acidor bicarbonate production by kidney, pancreas, or

duodenum.

Anatomy and Physiology of the SkinThe joint meeting of the anatomical and physiological

sections concerned itself with the skin. Prof. H. BARCROFTmade an enlightening survey of the methods used in

measuring the blood-flow through the skin ; he pointedout that most of these methods are applicable only tothe skin of the extrem ties. He went on to describe ameans of measuring blood-flow through the skin of theforearm by a method of differences after closing the skinvessels on one side by electro-diaphoresis of adrenaline,and the assessment of venous dilation by infrared

photography. The application of these methods hasshown that there are no vasodilator nerves to the fingers,and that there are vasoconstrictor reflex arcs to the fingersmediated through the cord in spinal man with lesionshigher than the 2nd thoracic segment, the stimulusbeing a deep breath.

Dr. C. A. KEELE summarised knowledge of the controlof sweating. He distinguished between emotional sweat-ing and thermal sweating by the site of the effect, at thesame time sounding a warning against the uncriticalacceptanee of the patterns described by Kuno. Afteran account of the pathways mediating the sweatingresponse and the cholinergic transmission of the impulsesto the sweat-glands, he went on to discuss hyperhidrosis.As his work with Dr. T. M. Chalmers has revealed noevidence of hypersensitivity of the sweat-glands of thepalms to acetylcholine in patients with hyperhidrosis, heconcludes that the abnormality probably lies somewhereon the central pathways.

Dr. R. E. BILLINGHAM Spoke on the anatomical basisof epidermal pigmentation, pointing out that theepidermis is made up of two distinct types of cells ;the majority are malpighian cells, which are interspersedwith dendritic cells containing a melanogenic enzymesystem. Using sheets of epidermis separated from thedermis by tryptic digestion, he has demonstrated thatthe dendritic cells alone form melanin and later transferit to the malpighian cells. The dendritic cells divideby mitosis, so they are a race of cells apart from themalpighian cells. The skin of white men contains as

many dendritic cells as that of negroes, but in the negrothese cells are much more active in forming melanin. Heinsisted on the importance of the dendritic cells in anystudy of the skin, especially in investigations concern-ing pathological pigmentations and depigmentations,including the greying of hair.

Dr. GRAHAM WEDDELL invigorated the meeting with astimulating account of the functional anatomy of theinnervation of the skin. He pointed out that heat spots,cold spots, and so on, always have underlying them anumber of receptor end-organs of the particular typeconcerned, whilst each hair is innervated by three separatenerve-fibres, and the beaded fibres concerned with painare usually interwoven. The subtleties of cutaneoussensation can be understood only when the functionalpossibilities of this rich three-dimensional network ofreceptors is borne in mind. Protopathic pain is the resultof sensory poverty. Dr. Weddell gave an informed, specu-lative account of the mechanism of blushing, the trophicinfluences of nerves, and the possible role of the

pain-fibres in the mediation of the triple response.

DERMATOLOGY

President : Dr. J. T. INGRAM

Pruritis V ulvaeAt a combined meeting with the section of obstetrics

and gynaecology, Prof. T. N. A. JEFFCOATE observed thatabout 10% of women consulting a gynaecologist complainof pruritus vulvae. In diagnosis it is important to distin-guish itching from pain, and also to be sure that theitching is really vulval. There is always a cause forpruritus vulvae, and the more careful the examinationthe more often will a definite diagnosis be made. Thecommonest cause is local infection (accounting for some60% in his series), but not all inflammatory lesions causeitching ; it usually arises only in the presence of tricho-monas or monilia. Other causes include glycosuria, whichis easily overlooked if only one specimen of urine is

tested ; various skin diseases; and possibly psychogenicfactors-though these are probably often wrongly -blamedthrough neglect of local factors. The other importantcause is nutritional deficiency ; this is found particularlyin old women living alone and also in many with achlor-hydria. The agents concerned include vitamins A andC and those of the B complex, and also iron, liver factors,and oestrogen. Thus signs of deficiencies should be sought,especially in the mouth. Possibly in some cases the localtissues cannot deal properly with the vitamins available.Achlorhydria may lead to failure in absorption ofvitamins. Of 46 women with achlorhydria 34 were

promptly cured when given the acid ; of these, 25remained permanently cured even though some eventu-ally gave up treatment. Vulval lesions associated withdeficiency states vary from slight pallor and oedema tothe typical leukoplakic appearance. Leukoplakia mayat times indicate general nutritional disturbance.

Dr. G..A. GRANT PBTBBKiN said that pruritus vulvaeis merely a label covering many different diseases. Theincidence is most marked in the 30-40 age-group, which

suggests that the onset of the menopause is not an

important factor. Skin conditions ca,using itching includepsoriasis, lichen planus, lichen sclerosus, neurodermatitis,