1434

microalbuminburia14 and the progression of earlynephropathy,IS the opposite is now thought morelikely and trials of low-protein diets are under way.

Hypertension is an almost invariable concomitantof established diabetic nephropathy and was initiallythought to be a late and therefore secondary feature. Itis now clear that arterial blood pressure rises early inthe course of diabetic renal disease.16 Patients with

persistent dipstick-positive proteinuria have a bloodpressure of 146/96 mm Hg compared with 123/75in normoalbuminuric controls;17 those withmicroalbuminuria have pressures, which although notabnormal by World Health Organisation criteria, areraised (135/89) by comparison with controls (122/75). 18 19 Effective blood pressure reduction slows thedecline of glomerular filtration rate20-22 and alsoreduces the degree of microalbuminuria.23 Thus

hypertension might be the trigger for renal failure.Two new reports24,2S support this view and propose amechanism for genetic susceptibility to diabetic renalfailure.The Guy’s Hospital group26 found that parents of

proteinuric diabetics were more likely to have

hypertension, and at the Joslin Clinic24 young adultswith diabetes for 14-18 years had a three-foldincreased risk of nephropathy if they had a

hypertensive parent. Does a genetic predisposition tohypertension determine susceptibility to diabeticrenal failure? Both the Guy’s and Joslin Clinic

investigators used red-cell sodium-lithium (Na-Li)countertransport activity as a marker of the

predisposition to hypertension ’27211 and both found themaximum velocity of Na-Li countertransport wassignificantly higher in diabetic patients with

proteinuria than in those without or in non-diabetic

14. Cohen D, Dodds R, Viberti GC Effect of protein restriction in insulin-dependentdiabetics at nsk of nephropathy. Br Med J 1987; 294: 795-98.

15 Bending JJ, Dodds R, Keen H, Viberti GC. Lowering protein intake and theprogression of renal failure Diabetologia 1986; 29: 516A

16. Mogensen CE, Christensen CK, Vittinghaus E The stages of diabetic renal diseaseDiabetes 1983; 32 (suppl 2). 64-78.

17 Parving HH, Andersen AR, Smidt UM, Oxenboll B, Edsberg B, Christiansen JSDiabetic nephropathy and artenal hypertension Diabetologia 1983; 24: 10-12.

18 Christensen C-K, Mogensen CE. The course of incipient diabetic nephropathystudies of albumin excretion and blood pressure. Diabetic Med 1985; 2: 97-102

19 Drury PJ, Tarn AC Are the WHO criteria for hypertension appropriate in younginsulin-dependent diabetics? Diabetic Med 1985; 2: 79-82

20. Mogensen CE. Long term antihypertensive treatment inhibiting progression ofdiabetic nephropathy. Br Med J 1982; 285: 685-89.

21 Parving HH, Andersen AR, Smidt UM, Svendsen PAA Early aggressive anti-hypertensive treatment reduces rate of decline in kidney function in diabeticnephropathy. Lancet 1983; i: 1175-79.

22. Parving HH, Andersen AR, Smidt UM, Hommel E, Mathiesen ER, Svendsen PAAEffect of antihypertensive treatment on kidney function in diabetic nephropathy.Br Med J 1987, 294: 1443-17

23. Wiseman M, Viberti G, Mackintosh D, Jarrett RJ, Keen H. Glycaemia, arterialpressure and micro-albuminuria in type I (insulin-dependent) diabetes mellitus.Diabetologia 1984; 26: 401-05

24. Krolewski AS, Canessa M, Warram JH, Laffel LMB, Christheb AR, Knowler WC,Rand LI. Predisposition to hypertension and susceptibility to renal disease ininsulin-dependent diabetes mellitus. N Engl J Med 1988; 318: 140-45

25. Mangili R, Bending JJ, Scott G, Gupta A, Viberti GC Increased sodium-lithiumcountertransport activity in red cells in patients with insulin-dependent diabetesand nephropathy N Engl J Med 1988; 318: 146-50.

26. Viberti GC, Keen H, Wiseman J Raised artenal pressure m parents of proteinuncinsulin dependent diabetics. Br Med J 1987; 295: 515-17.

27. Canessa M, Adragna N, Solomon HS, Connolly TM, Tosteston DC Increasedsodium-lithium countertransport in red cells of patients with essential

hypertension. N Engl J Med 1980, 302: 772-76.28. Hilton PJ Cellular sodium transport in essential hypertension N Engl J Med 1986,

314: 222-29

patients with renal disease. In the Joslin Clinic study,the maximum velocity was similar in diabetic patientswith microalbuminuria, persistent proteinuria, or

renal failure; this finding excludes the possibility thatthe results were due to uraemia. Most otherenvironmental factors known to affect Na-Li

countertransport velocity (eg, degree of glycaemiccontrol, oral contraceptive use) were also controlled.How this genetic abnormality might lead to renalfailure is unclear. Young normotensive children ofhypertensive parents have higher glomerular filtrationrates and renal plasma flows than the children ofnormotensive parents29 and in the presence of poorlycontrolled diabetes these abnormalities might bemagnified and lead to raised intraglomerular pressure.Another possibility is that poor glycaemic controlcould produce vasodilatation of preglomerularvessels,3° which would expose the glomeruli to

systemic blood pressures. A combination of the twomechanisms seems probable; in the Joslin Clinic

patients, the risk of nephropathy was substantiallyincreased with poor diabetic control, although only inthose with a genetic predisposition to hypertension.Follow-up studies will be required to confirm thegenetic and predictive aspects of a high Na-Licountertransport velocity and it seems likely that thiswill not be the only factor involved since some patientswith nephropathy have normal rates. The next stepwill be a long-term prospective study of

antihypertensive treatment of susceptible patients(those with high rates of Na-Li countertransport)before microalbuminuria develops. However, manyclinicians will shrink from treating a blood pressure of135/90 in a 25-year-old with IDDM and the

justification will require a careful cost-benefit analysiswith particular attention to quality of life and possiblemetabolic side-effects of the antihypertensive drugs.

Cryptococcosis and AIDS

CRYPTOCOCCOSIS, the systemic infection causedby the encapsulated yeast, Cryptococcus neoformans, isan uncommon sporadic disease that occurs

throughout the world in both previously healthy andimmunocompromised individuals. Although it is a

respiratory infection, the most frequent clinicalmanifestation of cryptococcosis is meningitis, whichfollows dissemination from the lungs. In Europe andmany parts of the USA, patients with diseases

affecting T lymphocytes, including those with AIDS,are especially susceptible. However, the course and

29. Branch G, Cusi D, Barlassini C, et al. Renal dysfunction as a possible cause of essentialhypertension in predisposed subjects. Kidney Int 1983; 23: 870-75

30. Hostetter TH, Rennke HG, Brenner BM. The case for intrarenal hypertension m theinitiation and progression of diabetic and other glomerulopathies Am J Med 1982;72: 375-80.

1435

management of cryptococcal infections in patientswith AIDS differ sufficientlv from that seen in othergroups to merit comment. The first and most obviousdifference is that the prevalence of cryptococcalinfections, even in countries where the disease wasformerly rare, is likely to increase. The reportedfrequency of cryptococcosis in patients with AIDS inthe USA ranges from 1 -9 to 9%; in most areas 6-7%get the infection.12 In the UK, according to

information from the Public Health LaboratoryService Mycological Reference Laboratory,cryptococcosis developed in 3-2% of the 1429 patientswith AIDS up to April, 1988; since this figure reflectsvoluntary reporting, it is likely to be an underestimate.If one extrapolates from these data, in 1988 four timesas many patients with cryptococcosis will be treated inthe UK than in 1983 and these numbers are likely toincrease. In practical terms, many hospitals will nowhave to deal with an infection previously considered tobe a rarity.The signs and symptoms of cryptococcal infection

in patients with AIDS are often muted. Meningitismay be virtually symptomless apart from a mildheadache. Changes in mood are difficult to separatefrom those caused by HIV encephalitis or other

secondary infections such as toxoplasmosis.Nevertheless, patients are usually infected by largenumbers of organisms whose spread is unrestricted.Cryptococcaemia, which is uncommon in other

groups of patients, may be detected by culture or evenstained smears of blood films in AIDS patients.3 Theload of cryptococci is reflected by high titres of

circulating polysaccharide antigen derived from theyeast capsule, detected by a latex particle agglutinationtest.

The laboratory diagnostic features of the infectionare also different. Changes in cerebrospinal fluid

(CSF) cell numbers and biochemical determinationsmay be very slight and it has been suggested thatcryptococci in AIDS patients often have small

capsules, making recognition difficult with India inkstain.4 The epidemiology of the infection has alsoaltered. There are two main variants of this fungus,known as Cryptococcus neoformans neoformans andCryptococcus neoformans gattii, which differ in

geographic distribution as well as in culturalcharacteristics such as growth on canavanine-glycine-bromothymol blue (CGB) agar. Thegattii variety waspreviously commoner in the tropics, particularly innon-immunocompromised individuals; yet most

isolates from AIDS patients, irrespective of their

1. Dismukes WE. Cryptococcal meningitis in patients with AIDS J Infect Dis 1988; 157:624-28.

2. Zuger A, Louie E, Holzman RS, Simberkoff MS, Rahal JJ. Cryptococcal disease mpatients with the acquired immunodeficiency syndrome Ann Intern Med 1986;104: 234-40.

3. Eng RHK, Bishbury E, Smith SM, Geller H, Kapila R. Bacteremia and fungemia inpatients with acquired immunodeficiency syndrome Am J Clin Pathol 1986, 86:105-07

4. Bottone EJ, Wormser GP. Poorly encapsulated Cryptococcus neoformans from patientswith AIDS II. Correlation of capsule size observed directly in cerebrospinal fluidwith that after animal passage. AIDS 1985, 2: 219-25.

country of origin, belong to the neoformans variety. Athird observation is that one of the most useful

diagnostic tests, the detection of circulating or CSFcryptococcal antigen, is subject to wide variations inpatients with AIDS. Whilst CSF levels usuallydecline with treatment, titres of circulating antigenoften remain constant and may even rise.12 It is notclear whether this pattern reflects failure to eliminatethe organisms themselves or merely the highmolecular weight capsular material. Whatever thereason, the persistently abnormal serum antigen levelsare likely to be important and indicate continuedinfection.

Compared with other systemic mycoses, thetreatment of cryptococcosis has been investigatedintensively and has been the subject of several largemulticentre studies to determine optimum drugcombinations and lengths of therapy. The first ofthese reports showed that the meningeal infection wasbest treated with a combination of flucytosine andamphotericin B.6 This work has been extended latelyto show that in non-immunocompromised patientstherapy should be given for four weeks. However, inAIDS patients neither of these regimens producessatisfactory results.7.8 Patients have a high frequencyof adverse effects due to drugs, including bone-marrow depression caused by standard doses of

flucytosine. There is also a high rate of relapse--40%in one retrospective study9-after apparent initialsuccess with amphotericin B and/or flucytosine.Many physicians would regard this figure as an

over-optimistic estimate of the relapse rate, which isoften higher, and would treat patients withintermittent amphotericin B therapy after the initialremission. Of necessity, this approach entails a

lengthy stay in hospital and closely supervisedoutpatient therapy, both of which are costly in socialand financial terms.New approaches to the management of crypto-

coccosis in patients with AIDS are urgently needed.Possibilities include transferring patients at an earlierstage to intermittent courses of intravenous

amphotericin B given as outpatient therapy, and use ofliposomal amphotericin B or one of the new oralantifungals such as fluconazole or itraconazole.Fluconazole penetrates CSF after oral administrationbut can also be given intravenously. Early studiesindicate that it can produce remissions in AIDS

patients and that patients can be transferred sooner

5. Rinaldi MG, Drutz DJ, Howell A, Sande MA, Wolfsy CB, Hadley WK Serotypes ofCryptococcus neoformans in patients with AIDS J Infect Dis 1986, 153: 642

6. Bennett JE, Dismukes WE, Duma RJ, et al A comparison of amphotericin B alone andcombined with flucytosine in the treatment of cryptococcal meningitis N Engl JMed 1979; 301: 126-31

7. Dismukes WE, Cloud G, Gallis HA, et al Treatment of cryptococcal meningitis withcombination amphotericin B and flucytosine for four as compared with six weeksN Engl J Med 1987; 317: 334-41

8 Grant IH, Armstrong D. Management of infectious complications in the acquiredimmunodeficiency syndrome Am J Med 1986, 81 suppl 1A: 59-72

9 Kovacs JA, Kovacs AA, Polis M. et al. Cryptococcosis in the acquiredimmunodeficiency syndrome Ann Intern Med 1985; 103: 533-38

10 Dupont B, Drouhet E Cryptococcal meningitis and fluconazole Ann Intern Med1987, 106: 778

1436

to outpatient therapy; it can be given orally long termto prevent recurrences. Itraconazole is active in thetreatment and long-term prophylaxis of cryptococcalmeningitis" and has been given orally either on itsown or in combination with flucytosine. The

optimum regimens for induction of remission andmaintenance therapy have not been established but,provided that their efficacy is shown to be comparableto existing treatment with amphotericin B, both drugsoffer reasonable alternative approaches to therapywith early mobilisation of patients. Assessment ofthese new treatments of cryptococcosis in patientswith AIDS is not bedevilled by the difficulties ofdiagnosis common to other opportunistic mycoses, sothere is no reason why well-constructed multicentrestudies should not provide the necessary informationquickly.

VIRUS DIAGNOSTIC SCANNINGELECTRONMICROSCOPY

Andersson and colleagues1,z in Sweden have latelydescribed a novel solid-state immunoabsorption techniqueallied to scanning electronmicroscopy (SEM) for thedetection of virus particles in various body fluids-eg, urineand serum from patients infected with cytomegalovirus, andcerebrospinal fluid (CSF) from patients with subacutesclerosing panencephalitis (SSPE). Briefly, 3-92 mdiameter latex beads were coated with monoclonalantibodies to cytomegalovirus envelope proteins andincubated for one hour in 100 l urine or serum.

Alternatively, beads coated with monoclonal antibodies tomeasles virus haemagglutinin were incubated in CSF. Thebeads were collected on smooth, small-pore filters and thewhole preparation was coated with gold and viewed bySEM. The coating necessary for SEM obscures fine

morphological detail; by contrast, the frequently usedtransmission electronmicroscopy (TEM) methods of virusrecognition are based on structural detail, which ischaracteristic for each virus group. Thus the gold-coated,blob-like particles attached to the beads could only beassumed to be viral because of the specificity of theantibody-mediated absorption and because of theirconsistent size.The sensitivity of the new technique for cytomegalovirus

detection in urine appears to be greater than that ofconventional TEM methods.36 Even absorption TEM

11. Viviani MA, Tortorano AM, Giani PC, et al. Itraconazole for cryptococcal infection inthe acquired immunodeficiency syndrome. Ann zo Intern Med 1987; 106: 166.

1. Andersson J, Nybom R, Larsson P, Andersson U, Britton S, Ehrnst A Rapiddetection of cytomegalovirus using immune scanning electron microscopy J VirolMeth 1987; 16: 253-62.

2. Andersson J, Ehrnst A, Larsson PH, et al. Visualization of defective measles virusparticles in cerebrospinal fluid in subacute sclerosing panencephalitis. J Infect Dis1987; 156: 928-33.

3. Montplaisir S, Belloncik S, Leduc NP, Onji PA, Martineau B, Kurstak E Electronmicroscopy in the rapid diagnosis of cytomegalovirus: ultrastructural observationand comparison of methods of diagnosis J Infect Dis 1972; 125: 533-38

4 Lee FK, Nahmias AJ, Stagno S. Rapid diagnosis of cytomegalovirus infection minfants by electron microscopy. N Engl J Med 1978, 299: 1266-70.

5. Coleman DV, Wolfendale MR, Daniel RA, et al A prospective study of humanpolyomavirus infection in pregnancy J Infect Dis 1980, 142: 1-8

6. Stagno S, Pass RF, Reynolds DW, Moore MA, Nahmias AJ, Alford CA. Comparativestudy of diagnostic procedures for congenital cytomegalovirus infections. Pediatrics1980; 65: 251-57.

methods (eg, by negative staining of virus particles absorbedon to antibody-coated grids) might not be as sensitive as thenew technique, in which the beads are agitated in the sampleduring incubation and present a large area for absorptionand subsequent observation. Nevertheless, cytomegalovirusculture was slightly more sensitive than absorption SEM.’New sensitive tests for cytomegalovirus early antigens in24-hour cultures7.8 are already in regular use and absorptionSEM appears only marginally more rapid. Culture mayyield false-negative results if virus particles are coated byendogenous antibody; this outcome is less likely byabsorption SEM, and Andersson et al plan to extend theirstudy to test this point.

SSPE is conventionally diagnosed by demonstratingmeasles antibody in CSF, and the role of absorption SEMindiagnosis is uncertain. However, the evidence that wholemeasles virus particles occur in CSF reveals a new aspect ofthe still uncertain pathogenesis of SSPE. The virus has mostoften been sought in SSPE brain, where it can be seen inTEM sections as intracellular viral nucleocapsids.1 9Budding, mature particles are not seen and the virus hasbeen extremely difficult to culture from brain tissue.""’Measles virus has been isolated 12 and the genomedetected’3 14 in lymphoid tissue, and measles antigens havebeen demonstrated in cells from CSF.15 Measles virus hasnever been cultivated from CSF and attempts by Anderssonand co-workers to grow the virus were also unsuccessful,despite microscopic evidence of mature particles.2 Alimiting factor may have been the presence of endogenousattached antibody, which might have neutralised the

infectivity of the particles and could have masked

haemagglutinin. Negative-staining TEM was also used onCSF and paramyxovirus-like particles were detected butwere difficult to recognise because they had a smootheroutline than normal and helical nucleocapsids could seldombe detected inside the particles. The published single TEMmicograph fails to convince. CSF has not been a fruitfulsource of virus for TEM: only isolated instances of

paramyxovirus-like particles in mumps encephalitis andmeningitis have been recorded.16,17

7. Gleaves CA, Smith TF, Shuster EA, Pearson GR. Rapid detection of cytomegalovirusin MRC-5 cells inoculated with urine specimens by using low-speed centrifugationand monoclonal antibody to early antigen. J Clin Microbiol 1984; 19: 917-19

8. Griffiths PD, Panjwani DD, Stirk PR, et al. Rapid diagnosis of cytomegalovirusinfection in immunocompromised patients by detection of early antigen fluorescentfoci. Lancet 1984; ii: 1242-44.

9. Hemdon RM, Rubinstein LJ. Light and electron microscopy observations on thedevelopment of viral particles in the inclusions of Dawson’s encephalitis (subacutesclerosing panencephalitis) Neurology 1968; 18: 8-20.

10. Chen TT, Watanabe I, Zeman W, Mealey J. Subacute sclerosing panencephalitispropagation of measles virus from brain biopsy in tissue culture. Science 1969; 163:1193-94.

11. Horta-Barbosa L, Fucillo DA, London WT, Jabbour JT, Zeman W, Sever JLIsolation of measles virus from brain cell cultures of two patients with subacutesclerosing panencephalitis. Proc Soc Exp Biol Med 1969, 132: 272-77.

12. Horta-Barbosa L, Hamilton R, Wittig B, Fucillo DA, Sever JL, Vemon MLSubacute sclerosing panencephalitis: isolation of suppressed measles virus fromlymph node biopsies. Science 1971; 173: 840-41.

13. Foumier JG, Tardieu M, Lebon P, et al. Detection of measles virus RNA inlymphocytes from peripheral-blood and brain penvascular infiltrates of patientswith subacute sclerosing panancephalitis N Engl J Med 1985; 313: 910-15

14. Foumier JG, Lebon P, Bouteille M, Goutieres F, Rozenblatt S. Subacute sclerosingpanencephalitis: detection of measles virus RNA in appendix lymphoid tissuebefore clinical signs. Br Med J 1986; 293: 523-24.

15. Dayan AD, Stokes MI. Rapid diagnosis of encephalitis by immunofluorescentexamination of cerebrospinal-fluid cells Lancet 1973; i: 177-79.

16. Doane FW, Anderson N, Chatiyanonda K, Bannatyne RM, McLean DM, RhodesAJ. Rapid laboratory diagnosis of paramyxovirus infections by electron

microscopy. Lancet 1967; ii: 751-53.17. Hemdon RM, Johnson RT, Davis LE, Descalzi LR. Ependymitis in mumps virus

meningitis. Electron microscopical studies of cerebrospinal fluid. Arch Neurol1974; 30: 475-79.