In a 4 1/2-year period, 4 of 68 children in a longitudinal study of neurological complications of human immunodeficiency virus (HIV) infection had clinical and/or neuroradiological evidence of stroke, yielding a clinical incidence of stroke in this population of 1.3% per year. During this period, 32 subjects died, and permission for autopsy was granted in 18 of the patients, including 3 of 4 who had clinical evidence of stroke. The prevalence of cerebrovascular pathological features in our consecutive autopsy series was higher than the clinical incidence. At autopsy cerebrovascular disease was documented in 6 (24%) of 25 children with HIV infection, including all 3 children who had clinical evidence of stroke. Four patients had intracerebral hemorrhages, 6 patients had nonhemorrhagic infarcts, and 3 had both. Hemorrhage was catastrophic in 1 child and clinically silent in 3 children, all of whom had immune thrombocytopenia. One child had an arteriopathy that affected meningocerebral arteries. In another child, the arteries of the circle of Willis were aneurysmally dilated. Two children had coexisting cardiomyopathy and subacute necrotizing encephalomyelopathy with vascular proliferation. These results suggest that stroke should be considered when children with HIV infection develop focal neurological signs.

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Very few quantitative observations have been reported on the effect of rate of breathing on the voluntary maximum breathing capacity (M.B.C.). Proctor and Hardy (1949) found that the M.B.C. was achieved at a rate of 30 respirations per minute (R.P.M.). At higher rates of breathing the ventilatory capacity was diminished. These observations are contrary to the findings of other investigators who regard a fast rate of breathing as essential in producing the largest value for the M.B.C. (Gray and Green, 1945;Baldwin, Cournand, and Richards, 1948). None of these investigators used spirometers which had been tested for recording errors (Bernstein and Mendel, 1951), nor were the observations made at controlled rates of breathing.The effect of rate of breathing on the M.B.C.of a group of normal subjects has been investigated. This work has been performed on a spirometer which is substantially free from recording error. It has been suggested that to control the rate of breathing impairs the subject's performance, but evidence is provided here to show that there is no sound basis for that opinion. THE DESIGN OF THE SPIROMETERRecently Bernstein and Mendel (1951) showed that a spirometer of the conventional pattern commonly used for the M.B.C. test could give records of breathing which were grossly inaccurate. The respiratory rates at which these inaccuracies occurred were determined by the mean depth of immersion of the spirometer bell in its water-jacket, while their extent was determined by the rate, volume, and wave-form of the respiratory air-flow. Because these factors are variable in human experiments, an appropriate correction factor, applicable to every estimation on any one apparatus, cannot be deduced. It was also shown that these inaccuracies were due, at least in part, to the inertia of the moving parts of the spirometer. This caused pressure changes to occur within the bell, and these, at certain respiratory rates, tended to excite i esonance in the water column in the water-jacket. The respiratory rate at which resonance occurred was dependent on the length of the water column.By altering the design it has been possible to build a spirometer which is substantially free from recording error up to a rate of 110 R.P.M. This range is considerably greater than is possible with our conventional (Knipping) spirometer, with which aspiration of water into the connecting tubes commonly occurs at respiratory rates above about 55 R.P.M.The design considerations were as follows:To REDUCE THE INERTIA OF THE MOVING PARTS.-This has been achieved as follows:Reducing the Mass of the Bell.-In order to do this the bell was made of aluminium sheet, which is very light and strong, and its proportions were altered so as to give a better ratio between contained volume and surface area. The ideal bell would have equal length and cross-sectional diameter. This ideal has been approached, though not attained, because a compromise was adopted in which the cross-sectional area was made twice as great as that of the bell of the Knipping s...

Multiple boosters of immunizations in asymptomatic treatment-naive HIV-1-infected patients may result in a specific immune attrition and vaccine-induced viremia. Short-term monotherapy with ZDV may have blunted these adverse effects. Hyperimmunization of HIV-1-infected patients may be detrimental unless accompanied by antiretroviral therapy.