Prospective analysis of long term control of mild hypertension on cerebral blood flow

A group of 12 otherwise normal elderly volunteers (mean age = 69.8 years), were detected to have mild hypertension. Cerebral blood flow (CBF) values were measured using 133Xe inhalation method prior to initiating medical treatment and repeated at 6, 12, 24 and 36 months after BP was adequately controlled and restored to normal (below 150/90). Results indicate that CBF values increased markedly during follow-up intervals at 6, 12 and 24 months but not at 36 months. Hypertension is known to be a risk factor for stroke and 4 of the 12 subjects subsequently developed symptoms of cerebrovascular disease (stroke, multi-infarct dementia or transient ischemic attacks) despite control of hypertension. Analyses separating asymptomatic and symptomatic groups indicated that the eight asymptomatic patients continued to maintain increased CBF levels throughout the entire three year interval, whereas the 4 symptomatic patients developed declines in CBF which began, and progressively decreased below the initial pretreatment values, during the second and third years.

Cerebral blood flow and brain atrophy correlated by xenon contrast CT scanning

Correlations between cerebral blood flow (CBF) measured during stable xenon contrast CT scanning and standard CT indices of brain atrophy were investigated in the patients with senile dementia of Alzheimer type, multi-infarct dementia and idiopathic Parkinson's disease. Compared to age-matched normal volunteers, significant correlations were found in patients with idiopathic Parkinson's disease between cortical and subcortical gray matter blood flow and brain atrophy estimated by the ventricular body ratio, and mild to moderate brain atrophy were correlated with stepwise CBF reductions. However, in patients with senile dementia of Alzheimer type and multi-infarct dementia, brain atrophy was not associated with stepwise CBF reductions. Overall correlations between brain atrophy and reduced CBF were weak. Mild degrees of brain atrophy are not always associated with reduced CBF.

Biochemical effects of corticosteroids on neural tissues

Corticosteroids appear capable of exerting an impressive array of effects on the metabolism of neural tissues. The diversity of these effects is perhaps not surprising given the wide variety of biochemically and morphologically distinguishable cell types present in the combined central and peripheral nervous systems. In conclusion, it seems useful to summarize the state of knowledge in some of the most critical research areas discussed in this review and to predict what major advances are probably forthcoming in the next few years.

Cerebral atrophy and hypoperfusion improve during treatment of Wernicke-Korsakoff syndrome

Nineteen patients with sudden onset of impaired recent memory, cerebellar ataxia, peripheral neuropathy, and other signs of Wernicke-Korsakoff syndrome (WKS) were treated and examined prospectively for 3 months. Serial studies included histories, neurological examinations, cognitive capacity screening examinations (CCSE), computed tomography (CT) scans, and measurements of regional CBF. Patients were detoxified and withdrawn from sedatives before CBF measurements were examined. Treatment included alcohol withdrawal, nutritious diet, and 300 mg thiamine daily. Before treatment CCSE scores and blood flow values of both white and gray matter were reduced, particularly within both temporoparietal regions. After treatment of compliant patients (n = 10), white and gray matter blood flow increased concurrently with improved CCSE scores. Abnormal eye signs, ataxia, peripheral neuropathy, and performance of activities of daily living also improved. Cerebral atrophy and ventricular enlargement measured by CT decreased. Early recognition and treatment of WKS in compliant patients permit rapid reversals of cognitive and neurological impairments associated with increased blood flow of gray and white matter and improvements of brain atrophy measured by CT scanning.

Adrenalectomy in the developing rat: does it cause reduced or increased brain myelination?

We have previously demonstrated increased myelination in adult rats that were adrenalectomized (ADX) neonatally. However, Preston and McMorris (1984) recently reported reduced myelination at Day 21 or 22 in day 14 ADX animals. The present experiment attempted to replicate Preston and McMorris' study to determine whether early adrenalectomy might be producing a transient hypomyelination prior to the hypermyelination observed at later time points. We were unable to duplicate the exact protocol of Preston and McMorris (which involved weaning at Day 18 with administration of saline and glucose drinking solutions) because of 100% mortality of our ADX rats by Day 20. However, using our standard mineralocorticoid replacement therapy which allowed the animals to remain with their mothers, all of the ADX rats survived, and we were able to assess myelination in these animals by means of standard biochemical methods. All measures showed absolutely no reduction in myelination in ADX rats compared with sham-operated controls. The discrepancy between the present results and those of Preston and McMorris are attributed, at least in part, to the early weaning procedure used by these investigators.

Xenon contrast CT-CBF measurements in parkinsonism and normal aging

Local cerebral blood flow (LCBF) and local tissue:blood partition, coefficient (L lambda) values were measured during CT scanning while patients with different types of Parkinson's syndrome (N = 14) inhaled a contrast mixture of 35-37 per cent stable xenon gas in oxygen. Single-compartment analysis fitted to infinity was used to calculate L lambda and LCBF values. Results were compared with results from normal age-matched volunteers (N = 24). Mean hemispheric (p less than 0.05) and subcortical (p less than 0.05) gray matter LCBF values were reduced in idiopathic Parkinson's disease (N = 11), compared to values from age-matched normals. Regionally, LCBF reductions included frontal (p less than 0.001), parietal cortex (p less than 0.05), caudate (p less than 0.05), lentiform nuclei (p less than 0.001) and thalamus (p less than 0.05) reductions. L lambda values were normal. Unilateral tremor and/or rigidity correlated directly with reduced LCBF in contralateral lentiform (p less than 0.01) and caudate (p less than 0.01) nuclei. In postencephalitic Parkinsonism (N = 1) LCBF reductions were diffuse, with normal L lambda values. In the akinetic form of Parkinsonism (N = 1) associated with lacunar infarcts, LCBF and L lambda reductions were patchy. In Parkinsonism following carbon monoxide poisoning (N = 1), LCBF values of gray and white matter were diffusely reduced and L lambda values were reduced in both pallidal regions. When dementia was present together with Parkinsonism (N = 3), LCBF reductions were more diffuse and severe. Dopaminergic deficiency correlated directly with reduced LCBF values, reflecting the severity of Parkinsonism.

Abstention from cigarette smoking improves cerebral perfusion among elderly chronic smokers

A cross-sectional study of cerebral blood flow (CBF) levels in 268 neurologically normal volunteers contrasting nonsmokers, smokers who quit, and current cigarette smokers indicated that subjects who quit smoking had significantly higher cerebral perfusion levels than subjects who had continued to smoke but remained lower than subjects without a history of cigarette smoking. All subjects were matched for age and sex, and smoking groups were matched for duration and amount of smoking. A prospective study of 11 subjects who were able to stop smoking in which CBF levels were available both antecedent to and following cessation of the habit indicated that significant gains occurred in cerebral perfusion levels within one year following cessation of smoking. A control group of 22 subjects who continued to smoke (matched for age, sex, duration of smoking, and duration of time between baseline and follow-up) showed no change in CBF values. A correlation between magnitude of CBF change and duration of cessation of cigarette smoking demonstrated a significant linear increase in CBF during the one-year period. These results suggest that elderly individuals who have smoked for three to four decades can benefit substantially by abstaining from cigarette smoking and that significant improvement in cerebral circulation occurs within a relatively short period.

Heterogeneity of breast carcinomas determined by flow cytometric analysis

Eight cases of primary breast carcinoma were studied for evidence of heterogeneity by flow cytometry using propidium iodide staining of DNA. Tumors ranged from 2.5 to 8.0 cm in greatest dimension, mean 4.2 cm. Five to 11 samples, determined by tumor size, were analyzed from each primary tumor in addition to 4 axillary lymph nodal metastases from 3 of the 8 cases. The presence of carcinoma was demonstrated histologically in each flow cytometric sample. Three of the carcinomas showed only diploid DNA content. Three showed the same single hyperdiploid population in each sample. Two carcinomas (2.5 and 3.5 cm) were heterogeneous and demonstrated 2 or 3 hyperdiploid populations. The 2 or 3 distinct hyperdiploid populations were present singly or sometimes in combination in one sample. Five of the 11 samples from 1 of the heterogeneous tumors and its axillary metastasis contained a single diploid population. Therefore, flow cytometric analysis of a single sample from a breast carcinoma may not be representative of the entire tumor. The study of multiple samples of breast carcinomas by flow cytometry is necessary for full characterization of the tumors.

Evaluation of treatment of normal-pressure hydrocephalus

Ten patients with dementia due to normal-pressure hydrocephalus were evaluated prospectively according to a planned, longitudinal protocol for 4 to 12 months. Information recorded at each visit included clinical history, medical and neurological examination, psychometric scoring by Mini-Mental Status Questionnaire, measurement of ventricular size and local cerebral blood flow, and partition coefficients (local lambda changes) (1 lambda) by xenon contrast computerized tomography scanning. Cerebrospinal fluid shunting was carried out in eight cases. Serial evaluations were repeated at intervals up to 8 months after shunting, and demonstrated that the ventricles decreased in size and periventricular hypodensities decreased. White matter 1 lambda values and blood flows and cortical gray matter flows progressively increased for 3 months after shunting, and remained increased except for one case complicated by chronic alcoholism. Clinical recovery correlated with improved cerebral perfusion. There were returns of urinary continence and improvements in gait and usually in activities of daily living. Mentation was the last factor to improve. Factors negatively influencing cerebral perfusion and clinical recovery were shunt failures and various contributing causes of dementia.

Age-related reductions in cerebral vasomotor reactivity and the law of initial value: a 4-year prospective longitudinal study

A group of 51 neurologically normal, middle-aged and elderly volunteers (aged 35-86 years; mean age 63.24 years) with and without risk factors for stroke were given annual tests of cerebral vasomotor reactivity to assess any changes in the cerebral vascular capacitance associated with advancing age that might alter cerebral vasomotor reactivity. Cerebral vasomotor reactivity was estimated as the difference in bihemisphere gray matter CBF measured by the 133Xe inhalation method in the steady state breathing room air, followed by a second measurement during inhalation of 100% oxygen. There were significant and progressive reductions in cerebral vasomotor reactivity during the 4-year longitudinal study. Positive linear correlations were apparent between initial steady-state mean bihemisphere gray matter CBF levels and degrees of vasomotor reactivity, suggesting that the Law of Initial Value plays an important role. This should be borne in mind when analyzing scores of cerebral vasomotor reactivity. In the present communication, analysis of covariance was used to correct for influences of initial CBF levels on vasomotor responses tested while breathing pure oxygen.

A comparison of human breast cancer cell kinetics measured by flow cytometry and thymidine labeling

Flow cytometric determination of tumor ploidy and S-phase fraction following collagenase dissociation and thymidine labeling was performed on 75 consecutive breast cancers. Estrogen and progesterone receptor levels and routine histologic examination also were obtained on each tumor. Cell viability following collagenase dissociation varied from 13 to 95% with a mean of 71%. Thirty-six tumors were diploid, four tetraploid, and four hypertetraploid, and the remainder had DNA indices between 1.1 and 1.9. There was no significant correlation between tumor ploidy and tumor size or estrogen receptor positivity or negativity. The percentage of cells in S-phase varied from 1.2 to 20.0% with a mean of 6.0% utilizing a rectilinear model for histogram analysis that integrated a 10-contiguous channel sample containing the lowest number of cells in S-phase (S-pFL). The mean S-pFL of diploid carcinomas (3.43%) was significantly lower than that of hyperdiploid carcinomas (8.38%). There was good correlation between S-phase fraction determined by thymidine-labeling index (TLI) and S-pFL (r = 0.772, p = 0.0001). S-pFL predicted whether a tumor would be above or below median TLI with an accuracy of 90.5%. Estrogen receptor-negative cancers tended to have higher TLIs and S-pFLs than estrogen receptor-positive cancers; however, there was no correlation between progesterone receptor positivity or negativity and TLI and S-pFL.

Pathogenesis of normal-pressure hydrocephalus--preliminary observations

Eight cases with well-documented normal-pressure hydrocephalus were studied prospectively for 6 months by history, neurological examinations, Mini-Mental Status tests, xenon-contrast computed tomography measurements of local cerebral blood flow, and cerebral xenon solubility expressed as partition coefficients. Local cerebral blood flow and local partition coefficients were reduced throughout frontal and temporal lobes, basal ganglia, and thalamus. Cerebrospinal fluid shunting procedures were carried out in seven cases. As a result, local cerebral blood flow and local partition coefficients increased toward normal, particularly in frontal white matter, frontotemporal cortex, and basal ganglia. Ventricular size became reduced and mental status improved. Local partition coefficient values were reduced by increased tissue water because low values confirmed cerebrospinal fluid diffusion into white matter, which resolved after shunting. Patients likely to benefit from shunting, including shunt failures requiring revision, were detected.

Long-term assessment of cerebral perfusion following STA-MCA by-pass in patients

A prospective study of mean hemispheric cerebral blood flow (CBF) correlated with clinical status has now been completed for the past 54 months. Thirty-eight patients underwent superficial temporal to middle cerebral artery (STA-MCA) by-pass. They were compared with 22 patients with similar arteriographic lesions and clinical symptoms, treated medically throughout the same interval of time. Assignment to either treatment group was not randomized but depended solely on choice of patient or treating physician. Both groups were matched for age, clinical symptoms, angiographic abnormalities, and CBF values. All patients had proximal occlusion of one internal carotid artery or intracranial occlusive disease of the internal carotid or middle cerebral arteries. CBF measurements and clinical evaluations were repeated at regular intervals up to 54 months following surgery or institution of medical treatment. Mean follow up interval after STA-MCA by-pass was 28.7 months and for medical treatment was 29.7 months. Mean hemispheric CBF values for STA-MCA patients became significantly increased 2 weeks after operation. After that, CBF flow values decreased. At 24 months after surgery, flow values for surgically treated patients were significantly higher than among those treated medically, although there were no differences in flow values between the two groups at 3, 6, 12, 36 and 48 months. Prospective clinical evaluations after STA-MCA by-pass were as follows: 12 (32%) improved with cessation of TIAs and/or neurological improvement, 16 (42%) remained unchanged, 7 (18%) deteriorated (due to new or recurrent strokes) and 3 (8%) expired. Clinical results were the same for medical treatment: 6 (27%) improved, 10 (46%) unchanged, 4 (18%) deteriorated due to new or recurrent stroke, and 2 (9%) expired.

CT-CBF correlations of cognitive deficits in multi-infarct dementia

Fifteen right-handed patients with Multi-Infarct Dementia underwent cognitive testing by the Jacobs Mini-Mental Scale (MMQ), and xenon contrast CT scanning. Local cerebral blood flow (LCBF) and local partition coefficient (L lambda) values were measured by stable xenon contrast CT scanning and potential methodological errors were discussed. Reduced values were graded: 0 = normal, 1 = mild, 2 = moderate, 3 = severe. Graded values were pooled and plotted on composite brain maps to display locations of abnormal L lambda and LCBF values. Topographic brain maps, showing most frequent locations of reduced L lambda values, confirmed the common anatomical locations of multiple cerebral infarcts to be distributed in both thalami, temporal lobes, basal ganglia, left internal capsule and right cingulate cortex. Gray matter flow values were reduced in similar cortical and subcortical regions. There were no correlations between MMQ scores and reduced LCBF values for caudate and lenticular nuclei. Direct and statistically significant correlations were found between reduced MMQ scores and mean LCBF values for left or right frontal cortex, left or right temporal cortex and left or right thalamus. Subgrouping MMQ tests according to functions assessed, indicated that left mid-temporal ischemia correlated with dyscalculia and memory disturbances while ischemia of both frontal lobes correlated with disorientation to time and place.

Progressive cerebral ischemia antedates cerebrovascular symptoms by two years

Prospective longitudinal cerebral blood flow values were serially plotted over a four-year interval against the course of cerebral ischemia before, during, and after onset of clinical symptoms. Of 161 normal subjects (mean age, 62 years), 86 were risk free and 75 had hypertension, heart disease, diabetes mellitus, and/or hyperlipidemia. Twenty-one subjects developed cerebrovascular symptoms during the prospective trial. Mean hemispheric cerebral blood flow values were significantly lower for at risk than for risk-free subjects. Symptomatic subjects showed lower values than those in either of the two asymptomatic groups at every session. Statistical analysis of cerebral blood flow values for symptomatic patients compared one and two years prior to onset of symptoms, at the onset of symptoms, and 1 year later showed reductions compared to asymptomatic risk-factored subjects tested in a similar prospective manner. Measurable declines in cerebral perfusion accompany development and progression of aortocerebral atherosclerosis prior to clinical appearance of signs and symptoms of cerebrovascular disease. If confirmed, these observations should permit the institution of preventive medical and/or surgical interventive measures and an evaluation of their outcome.

Cerebral blood flow changes in benign aging and cerebrovascular disease

Cross-sectional analysis of CBF values was carried out among 668 volunteers and patients. Subjects were subdivided according to age, gender, and degree of cerebrovascular disease, ranging from healthy volunteers with or without risk factors for stroke to patients with multi-infarct dementia. Four-year longitudinal analysis was also carried out on 230 individuals from the original sample. Decrements in CBF values were evidenced by both cross-sectional and longitudinal analysis in relation to advancing age, progressive cerebrovascular disease, and dementia. Regional, age-related CBF declines in healthy volunteers were heterogeneous, possibly related to changes in levels of functional activity within different brain regions.

Xenon contrast CT-CBF scanning of the brain differentiates normal age-related changes from multi-infarct dementia and senile dementia of Alzheimer type

Local cerebral blood flow (LCBF) and partition coefficients (L lambda) were measured during inhalation of stable xenon gas with serial CT scanning among normal volunteers (N = 15), individuals with multi-infarct dementia (MID, N = 10), and persons with senile dementia of Alzheimer type (SDAT, N = 8). Mean gray matter flow values were reduced in both MID and SDAT. Age-related declines in LCBF values in normals were marked in frontal cortex and basal ganglia. LCBF values were decreased beyond normals in frontal and temporal cortices and thalamus in MID and SDAT, in basal ganglia only in MID. Unlike SDAT and age-matched normals, L lambda values were reduced in fronto-temporal cortex and thalamus in MID. Multifocal nature of lesions in MID was apparent. Coefficients of variation for LCBFs were greater in MID compared with SDAT and/or age-matched normals.

The effects of chronic cigarette smoking on cerebrovascular responsiveness to 5 per cent CO2 and 100 per cent O2 inhalation

Effects of chronic cigarette smoking on cerebrovascular responsiveness of volunteers at risk for stroke and not at risk for stroke were evaluated by serial measurements of cerebral blood flow using the 133Xe inhalation method. Resting gray matter blood flow values (Fg) measured while breathing room air were compared with Fg values measured during inhalation of either 5 per cent CO2 in air or 100 per cent O2. Changes in Fg values during inhalation of 5 per cent CO2 were used to estimate cerebral vasodilator capacitance, and those during inhalation of 100 per cent O2 were used to estimate cerebral vasoconstrictor capacitance. Results indicated that chronic cigarette smokers have both reduced vasodilator (P less than 0.01) and reduced vasoconstrictor (P less than 0.02) capacitance when compared with nonsmokers of the same ages regardless of whether or not other risk factors for stroke were present. Vasodilator capacitance to 5 per cent CO2 inhalation was reduced among smokers compared with nonsmokers of the same age by 48 per cent in non-risk subjects and 56 per cent in risk-factored subjects, while vasoconstrictor capacitance to 100 per cent O2 inhalation among smokers was decreased by 24 per cent in non-risk subjects and 34 per cent in risk-factored subjects. In risk-factored subjects, combined effects of smoking and other risks appeared to be additive.

A method for dissociation of viable human breast cancer cells that produces flow cytometric kinetic information similar to that obtained by thymidine labeling

Collagenase dissociation, performed on 40 human breast cancers, yielded between 1 million and 50 million cells from less than 1 g of tissue from each tumor. Approximately 60% of cells (mean) was considered viable as judged by trypan blue exclusion and phase microscopy. On subsequent flow cytometric analysis, 20 cancers (50%) were considered diploid, three were tetraploid, and the remainder, hyperdiploid. Thymidine labeling (TLI) and flow cytometry following mechanical dissociation also were performed on 23 of these 40 tumors. Among this group of 23 cases, the median percentage of S-phase cells obtained by collagenase dissociation was 5.4, by TLI was 5.7, and by mechanical dissociation was 9.7. There was excellent correlation between the percentage of S-phase cells obtained by collagenase and TLI (r = 0.847, p = 0.0001) but only fair correlation between the percentage of S-phase cells obtained by mechanical dissociation and TLI (r = 0.597, p = 0.0027). The percentage of S-phase cells obtained by either collagenase or mechanical dissociation predicted whether a tumor was above or below median TLI in 19 of 23 cases (p = 0.0018). Estrogen receptor positivity or negativity did not predict whether a tumor was above or below median TLI (r = 0.283, p = 0.130) or above or below median S-phase fraction following collagenase dissociation (r = 0.218, p = 0.182), nor did quantitative estrogen receptor correlate significantly with TLI (r = 0.283, p = 0.13) or S-phase fraction (r = 0.218, p = 0.18).

Practical breast carcinoma cell kinetics: review and update

The S-phase fraction (SP) measured by flow cytometry of DNA and the thymidine labeling index (TLI) measured autoradiographically indicate the proportion of carcinoma cells currently synthesizing DNA and reflect the rate of proliferation. The TLI and SPF are lognormally distributed. The median TLI performed to maximize precursor uptake is near 5% (5 labeled carcinoma cells per 100) the mean near 7%, and the range from less than 1% to near 40%. Corresponding values for the SPF measured by DNA flow cytometry are slightly higher when appropriate measures are taken to reduce background debris counts and other artefacts. Residual elevation of SPF above TLI may result from S-phase arrested cells. Flow cytometric histograms show that clearly aneuploid cell lines exist in 50-80% of primary breast carcinomas. Aneuploid breast carcinomas have higher mean TLI than diploid breast carcinomas, and therefore proliferate more rapidly. They also more frequently lack estrogen receptor (ER). Carcinomas with minimal nuclear anaplasia, particularly those of tubular, mucinous, infiltrating lobular and adenocystic types have low TLI and SPF, whereas carcinomas with highly anaplastic nuclei, including medullary carcinomas, have high TLI and SPF. TLI and SPF correlate inversely with ER and PgR content, have no relationship to axillary lymph nodal status, and have a weak positive correlation with tumor size and a weak negative correlation with age. High TLI predicts a high risk of early relapse after primary therapy for both node-negative and node-positive carcinomas. Carcinomas that produce brain metastases have particularly high TLI. Current evidence suggests that high SPF and aneuploidy may prove to have prognostic significance like TLI.