La dimensión territorial como determinante de la marginalización ocupacional

in n e a te r oonseoWatlon in the eluate. This was put in . the froesing empartmemt of a refM gm ator for 20 minutas aftm Whioh a w ystalline preeipitate had usually formed. This was spun down and rstaovsd, and R» supwmatant was dried overnight in a vacuum desiccator. I f two extracts were being dried to^R m r, as was the ease, th is could be achieved overnight by putting the two beakers in

-33m

B with four patrie dishes eaeh oontaining 30*35

grammes o f phosphorow peatoadMte, end rsdoelag the pcwmse to about 20 zm.%. %h the nwrniiig the so3xiti<»s mboUbd

have a volta» of 1*2 ml. foe pH of the egctraots mas adjusted to 6.5 * 7*0, and fo elr roluae was oeaeured. fo ^ wrae tfaaaa

rerty for injeotioB.

foe preparation is that of Ames and Vian Dyke (1952). foe animals used ware Wistar r tlte rats

between 200 and 2$o grammes, four animais ware givoa an

in itia l load of 105 efoyl aleohol equivalent to 55 of th e ir body weight. An assistan t held the sat with its neak

esteaded idiile the aleohol was injected into the stomaeh throu(di a 4 Bnglish gauge jBaquss oathster lu b rirtted with paraffin* I f a thizsasr catheter is used theare is a greater dfloager of entering the troeliea Instead of foe oesophagus, and a stouter cme is d iffic u lt to psM. foe ra ts were foaa put in separate cages v ifo the floors lined wifo blettim g p^per. Aftwr h alf an hour the ra t mhifo bad passed the

largm t volime of urine was selected for the assay (B issett, 1959). I t was giwen a further load eqoivaleet to 35 o f ifo body w ei^it) fo is load was watw i f the appeared

WMPy drowsy as a resu lt of the in itia l 105 alcohol im jeetioa, but i f i t r ts fk irly aetlwe was givm 25 or 25 aleohol fo r the second load, as fo is rodooed foe quantity o t efowp nsQded to be giwen Xatwr.

ttm selected amimcl, which now had a load of about

% o f body wai4dxt was pas^parad tgr focmettag pcdythana

cafoatars Into its stoaafo, bladder and jugular w rta. Shis w ill no doubt praeort ao difrsaolty to ana paaotised In

animal preparation, but, m one not with tbs

technique, I found the following praetim l pointa of great assistance.

rnataMBMBfitoi. Ginso i t Is o f i#*wptaoce foot foe prepuation of the ra t fosuld be done with the Mnimm of delay and trauma, i t inexeasc» foe chances rtrte ss i f as adaqcate «may o f instruusmts is laid out bofowfoemd. foe aeleetion foown on the tr tle in Pig. 1 baa been fomd to be satiefootory# foe ccarme foreeps are not neeosMxy for the dissection, but foey axe usefol Whan passing foe Jaques dsthatMP in tbs wm sciort ra t to gfoe foe water load, foe fine pointed soissore are reserved for — a nlxtk is foe w rta, and fo r cutting akin, for eaca^e, foe coarser ones are asod. foe two «Aery forceps sfould be sm all; they «pe used chiefly tor bolding foe U gafores so «I to maintain the «dm under acme tmasiao before i t is Opened, but i f th«r are too heavy they pull too mufo on the woim vmd any cause i t to go i r t ) spasm, foe matmxted needle is ideal for blunt dissection, and the small object meat to i t is a c lip made from a large safety pin. fo is is la -

Nï

m

- -30“

la te r. TtM linen thread is used to tie o ff the urethra and •M xre the eatheter in the hladdar, while the eottoa is %wed for tying foe vein and sewing up foe Im iaions. Also required, but not shown in fig . 1 are a {An, and a needle with a cutting edge for sewing the RdUx. Before startin g

foe disseetion two piwMS of cotton foread are out o f four and eight foohes respeetively, wad too four inch Irtgtfas o f foe Unen thread.

ffr)i iftniP>«fo—3a- I f the ooneenteation o f aleohol in the loading doses has bert oorreetly foosen the ra t should be O rtsoirts and aMe to walk about, a lb e it unsteadily.

Surgioal rtaesthesia is easily Indueed wifo efoer on cotton wool, and a satisfoctory level has beca achieved when the

ra t can be laid <m its b art on the disseotiz% board and dort a rt respond to a akin incision in the n ert. I f too each efoer is givaa the breathing bortote laboured, and foe animal nay develop pulmonary oedema *md d ie. Efoer is a stimulus for the release o f p o s^ ricr piteitaxy hormones, so i f foe ra t requires a long or deep ether anaw thetic i t w ill be slow in establishing a diuresis aftwwerda. foe

lig h t rtsesthsala is contrary to the terms o f foe Oam Office e e rtlfio a te , and i f foe animal is alarmed cr in pain th is also w ill teute an antidim raaia. Sdeelly, therefore, the

prwBSdicaticm wifo alcohol foortd be sufo Rmt a little efoer is su ffieiw it to covw the shccFt parted o f surgieal interforenee.

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(a l. R » digaartinn. I f the operator is oonfidert la his s b ill^ to «uarwlste a jugular soin te aot mors teaut f lf teon ateotss foan tho f ir s t stage o f the dt sweet ion should te to

tie o ff foe urefore. th is ensiaes that whMi foe stage is reafoed a t whisfi a osfoeter is to be put te the bladder the la tte r is fo il o f urine and hmee ee«y to find* Uuwever i f foe urethra is tied o ff, «id the oanm lation o f foe vein takas longer than ims eageoted, urine produet lwi say be

suppressed owing to the back pressure eonrtod on the kidnoys. Tho bogtener any therefor e prefer to s lip o ff the urethra with the rtip described in seetlcm a .

The oam nlation of a jugular este Is foe most d iffie a lt part o f the «w paretion but the foUoeing pro­ cedure prrtoWLy nakas i t as simple as is pcAsible. The animal is planed on a d issectit^ board «ifo its bead to­ wards the <gperator, the nert emtrtded, and the position of

the head steadied by means o f an e la stic bond put round the board «id flwer the r a t's veppar teeisw teeth . I t is net tied down in any othw way. A m ld-ltee teeteiw i is made through skin about an inch long with the lower end a t foe supsaatam al aoteh. foe opanii% is refoaeted to one side and the jugular vein is usually seen in the lownr (eamdol) part o f the inoiaion passing below foe o lariele; above i t is ocmered by a small but omspieuoue pad o f fo t. A shtmrt length of the wain is freed by bdunt disseetion and the

•35-

foofftwr plsoe o f eott<m thread Is pa^md rocraS it« As a resu lt of the ataüpulatlcm the vein may w ell go lato spaas, but tlAs is ao disadvaatage. the foread is lo ft in place and the in s ls irt is xefoected to foe otSwr sid e, and foe other jugular vein is sim ilarly eaposod. I t is probable that the second vein wiU be dilated «ad easy to dissoct be«n»e i t is carrying the blood normally carried by the vein f irs t esposed, now in sp a n . I f the f ir s t vein is also cnducting freely the eofon loop armmd i t is g n tly

pulled so as to obstruct i t tem porarily, and fo is w ill have foe effect of eousing the second to distend. The m g a r piece of cotton is passed round the second vein as a double lig atu re, n d the half o f foe ligature pm tw al to the heart is put under tension and held by foe woigrt of a pair of

ttttmry fbreeps. foe d ista l section o f vrtn w ill now become fUUy distended, and foe blood in i t is tx rtP rt by tyixgc the d ista l li^ctu re a t a point about $ inch froai foe prooAaal one. foe loop rotsad foe vein on foe other side is now

released, foe ligated section of the vein to be caaoulated is nicked vifo the fine scissors and the polyfoene oathetw (outside dim eter 0.0*»0 fofo; inside dim eter 0.028 inah) is ineerted tbrw gh the hole. To do th is is made very easy i f the shaft of a Bo. 24 8.U.O. hypodeotdc nradle is mounted in foe tip o f foe cafosfor wifo about § inch protruding, foe needle is fin er and casiee to d irect than the polyfoeme,

-36-

and I t Is easy to see how far i t bas bam iosm tad. foa aad of the needle most, of eoursa, be earafblly blunted. The pvoaAaal ligature is tied fXaely somd foe aeedle. foe loop sound the vein <m the othm side is removed, and care is

tfoen to see th at the vein on th at side is not tw isted sad is eondoeting blood freely , foe R da inoisioo in the nsRc is eloeed with cotton thread.

foe next step is to tie odTf the uzrthsa i f th is has not sAready been dona, foe board is reversed so th at the r a t's ta il is towards foe operator and a mid-line in- e ls it» about <me inch Im g is mado Rwxu^ the abdominal well with the mudal end a t foe ^rmpbysls pubis. I f foe

bladder is fu ll i t can easily be made to come out by gentle pressure with foe fingers a t the sides foe insision. If i t is empty i t w ill be necessary to lamt for i t among the gut and th is causes undesirable trauma to the ra t; i t is b etter to w ait u n til i t f ills . Khan foe bladder has beam asprooeod a pair of artery fbreepe is eliigiad onto foe apox and le ft in position tsatil foe cafoatw is ready to be tied in . fo is is a psecauti«i against foe bladder slipiAag beak and being lo st a fte r i t has been opened, o r rtse bei%%

tw isted r t its base in the course of the M tbeteriaatloo. A small pad of cotton wool is put over the incision to

prevent urine running into the abdominal cavity and the

—37--

re g lrt a t the apex. The cafoeter Is a prtytbsns tuba of OÜLO Info outside dlM aetar, OX# info insida d irto te r, and about 4 infoes long. The «id to be inserted in foe bladder is passed rapidly foroogb the tlam of a Bunsen burner;

fois omises the prtythane to e a rl ooteante and so fora a flange which nakw i t anfo easier to tto foe tr te into plaee securely, foe prepared mod is Inserted Raough foe insision «ad bald in plaee with foe slip ; the artery forceps axe

foen ranooBd and the catheter is tied in . foe abdoainal i»>

eistsn is than eloeed vifo ears aot to tw ist foe rtth rte r.

A fine polythene aatlieter (0.(5» info outside diameter) with a flanged tip is now passed into foe stomach fopoufo the mouth and the susglfol preparation is complete.

(d ). foe water load. A load «pial to betwefo 5 and 95 o f

body w el#it Is aatisfbctcfor; soallmr loads are usually act suffSciaet oompletely to ifo itd t eado^aous an ti-d in retis hormone secretion, while l«% er loads make foe ra t in- seneitSve In its response to foe in je c tirt o f small

quantities of hormone. A ra t with a load is about 3 to 5 times acmt sfositiVB then oas wifo a 95 load, so i t is isgiortant that the chosen load should be maintained a t a constant lev el. Zn most of foe «Brtys a load of about 85 was used.

—38»

In order to hasp the load ooceRaat the ra t la h a# a t ooMtont walgbt. She balawaa rtown In fig* 1 la f l » t

adjusted ao tb at the rig h t band aide with the dieeeetion board with the £lax to the drw-eoumting gap pXagged In , and with a blanket of orttoa wool, la balawioed by foe le f t hand

pan with a baahær o f lead abot. foe ra t ia ylaaod tm foe board and oowrod with the cotton wool» Wci#ita are placed on the le f t band pan equal to the desired leaded weifot o f the ra t, and water is given to the ra t by stoaoafa tube u n til the balance is again lev el. (In fig . 1 the cotton wool

blanket has been removed from the sat for purpoees o f the photograph, th is is whj' tbs rig h t side is shown to be UfdA). foe intravenort and Intragaafoia oafoeters, foown in fig . 2 , ere arranged so tb at they do not in terfere with the eaxrandons of the balance pens, cm the baJüttiee used an inequality o f 1 gXBQoe betwemi the pans is Indicated by a dafLoetiim o f h alf an info between the pointers) the lead eaa thereftee oM ily be eoDtrdlled vifoin these lim its*

fe l. îteaoadti^ af mSi» tUm foe StlMUlt applied tO the srtje e ts in th is Izmestigatiom eexmod a release of

hotncme of the axàm o f 50 ad lliu n its, o f fo is about 5 m illi-

tsoits was eoBcreted in the urine, of th is about 3 adUlxmlts could be extracted and dissolvad in 2 a l r t w ater, foe solutions to be assayed therefore were o f a s tr ength o f

•39“

easQ be given as a dose i t follow tta t the ra t must a t lea st give a good xoapame to 150 miermmits, and pseferaWy to

mah Ima. The method of recording urim flow rate focsaraây wed by B issett e t a l (1^%) was to collM t foe urine over pwiods of five sdm tes and base a calculation of tbs

activ ity of hoxBX»» injected on Rie dWLoution of floe during the sortnd and foird periods a fte r the injeettosu This method Is quite satisfhetoxy whan l«% e doses of

horoKme are given, bat the aatidiureeis resulting from the injection of 150 mimpoonits say not la s t as aueh w fifteem aiwibes, so foat tills aefood of recording is inaccurate end in e rtsitiv e . The ideal is obvlwaly to record contteuoasly, in t^ ra tin g ovor shcoter periods) one minute is a ecm-

v en irtt time. I t is not %xactloable to do tid s tor pnioS»

o f about five hours wifoout scks» mitooatic reoording appera- fos, and that (tesoribed by Dettelbech meets the so- qpirsmmits. His asfood is , pertsqis, overrtsbocate, and its eonplaxlties do not nseessarlly Iw d to the desired end. foe apparatus is a modification of that of Boors and P ieter (1953) rtie h ww almost equally aowplteatnd. In uettelbM b's version the urine is made to displeee a solut i on o f 15 salin s in 505 al eohol rtlfo fa lls as 0*005 ml d rrts througb e

oomxting gap and «pesâtes a foorpe inpulse ooimter eb ite records on a kymograph drum, foe dn%xs axe coUeeted in a ftenel brtou foe gap and fad into a fobe. foen 0*1 d has

-4ù-

eortHBlated In foe tube foie «vont te reoorâaâ, the trte te foptte d and an eqiml volume a t fluid is dalivw ed Into foe r a t's stonafo.

foe BHVpoae of eaualng the urine to dteplaee the aleobol-eaiine is ao th at "soall drops of uniform sire and acafoietivity are insw ad." foe former cdxjaetive is mot achieved siaoe i t has bemi shown that the stee r t dregrx te affSrtad by sfoy facto rs, among foam the rate a t white the drops are prortoed* OWiously i t is an w sen tial eoeditiom of the assay teteniqoe th at the rate of dropping teanld very, and so too w ill tl» sise of drops despite a ll preaamttems. foe second objective Is achieved, but the use of a sim #e trig g w a ire u it deeeribed te ta r mabes i t onaeeeaaary. foe ohjaatioQ to the dteiAaoemeot method is th at i t is m um- wrttad eoag^Utoatloo and foat i t may be a source of w rw i t

an a ir btehle is trapped in the reservoi r of alaobol-saltee, i f the level of foe oufolow is aot carefully adjusted so th at there is no hydrostatie pressure tranw dttad bate to foe tAadder, or i f there is a la te asywhwe in the system.

foe pwpoae of foe automatie replseeouxt o f urine by an e#«ml volume o f fluid into foe r a t's stomach is te