I n previous work 011 peripheral arteries the law of lL:iplac.e has i)eeii applicd to the pressure-volunle data to licld the el'tstic ro~istants and intcrrc8~ltion of function of elastin and collagenous fibers in the wall, and the changes with age. Siinilar an;ll>sis of major brain arteries has bee11 made on autopsy speci~~lens, ,~ged 2 to 90. Voluilze (micrometer syringe) aild pressure (clcctror~l,~no~mcttr) i l l arterial seglnet~ts were accurately measured. Absolute vol~lrnes were obt'lined hv rollapsing the artery with negative pressure, and tkne7>un.;tretched circunlferences" of the vessel were deduced fro111 the curves. i ension-circunaferei~cc c-urves were constructed. These showed the characteristic-increztsing slopch (increased "elnst~nce" or "stiffness") with incre;~>ing degree of stretch, iriterpretetl rls successiv~ " r e c r u i t r~~~i~t " of collageil fibs-5 ;I$ thty reach their u~rstrctc-hed length.Inirrenses in arteri,ll lvngth with distensioi-i were very sm,lll ,rnt4 negligible i i l vessels older than 30 years. hInxinium slope (stiflness) was reacheti a t pressures in the ph>siological range. 'l'he mauina,ll stretch wnh 26 to :3)iG, for vessels .~gc>e% 30 to 90 years. 'I'his is less than for peripheral arteries, except thobe over 80 ye~lrold..\geing showcd itself nlctin1y ill rcductioi-i of the stretch requir-ed to brii~g 50' ; of the collagen fibers to their l~nstretched length, i.e. in the "degree (>I blackness". 'l'his was ;3O(:/;, st retch for yoilnger vessels, 20' 7; for the older. T 7 iilike the periphe~ ,li arteries, the brain arterie.; show no sigriiiicanlt increase with age in the n~;txim:tl stiffness (re1,tted to their total collagen content). 'The nlenn valac of the P'oung1\ modulus of the wall a t high pressures was 1.93 & 0.67 X lo7 d l i~es:/scl.cin. No significal~t ~h , l~i g e ill thickatess of the wall or lurnci~ di,~nieter with ,lgc was founci.I t is concludccl that the major brniia .lrteries are less distensible t hail peripher;~l arteries of coinp;lrL~ble diameter, particular])-ill youth 13istensibilit>r decreases with age, mainly because the "degree of slacki~ess" of the collage11 fibers is rcduced. ,It ph>siolo~ical pressures the rn'ljor resistallce to distension is due to the collagei~ iihers rather than tc) the c.lastin fibers. avhich appear histologic;illy t o be Its, abund,tut, except it1 the elastic a interncz, t h a~l in peripheral nrterles.

M icroalbuminuria (MA) represents a range of urinary albumin excretion that is an important marker of cardiovascular (CV) risk in persons with and without diabetes. Moreover, progression to macroalbuminuria or proteinuria indicates an increased CV risk and the presence of kidney disease. Therefore, MA should be looked for and measured with a procedure that offers a high level of sensitivity and specificity, so that diabetic nephropathy and CV disease can be treated as soon as this risk factor appears.To fully understand the differences between the tests used to determine MA, it is important to remind oneself of the definitions of sensitivity and specificity. The sensitivity (true positive rate) of a test is its ability to detect individuals who are known to have a disease or finding (expressed as true positives/true positives plus false negatives). The specificity (true negative rate) of a test is its ability to detect persons who are known not to have a disease or finding (expressed as true negatives/true negatives plus false positives). The false negative rate is equal to one minus the sensitivity, and the false positive rate is one minus the specificity. This paper presents an overview of common tests used to screen for MA. It focuses on newer tests that have a higher sensitivity and specificity to detect lower levels of MA. CONVENTIONAL TESTS FOR MA Dipstick MeasurementMA is usually defined as 30-300 mg/d, whereas the albuminuria detected with the usual dipstick test represents a finding of >300 mg/d. The traditional test in the office setting to screen for MA has utilized a variety of semiquantitative dipsticks. These tests involve wetting a chemically impregnated test strip with a sample of urine. If a test is R e v i e w P a p e r

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