Cerebral Perfusion Pressure is Maintained in Acute Intracerebral Hemorrhage: A CT Perfusion Study

BACKGROUND AND PURPOSE

Although blood pressure reduction has been postulated to result in a fall in cerebral perfusion pressure in patients with intracerebral hemorrhage, the latter is rarely measured. We assessed regional cerebral perfusion pressure in patients with intracerebral hemorrhage by using CT perfusion source data.

MATERIALS AND METHODS

Patients with acute primary intracerebral hemorrhage were randomized to target systolic blood pressures of <150 mm Hg (n = 37) or <180 mm Hg (n = 36). Regional maps of cerebral blood flow, cerebral perfusion pressure, and cerebrovascular resistance were generated by using CT perfusion source data, obtained 2 hours after randomization.

RESULTS

Perihematoma cerebral blood flow (38.7 ± 11.9 mL/100 g/min) was reduced relative to contralateral regions (44.1 ± 11.1 mL/100 g/min, P = .001), but cerebral perfusion pressure was not (14.4 ± 4.6 minutes(-1) versus 14.3 ± 4.8 minutes(-1), P = .93). Perihematoma cerebrovascular resistance (0.34 ± 0.11 g/mL) was higher than that in the contralateral region (0.30 ± 0.10 g/mL, P < .001). Ipsilateral and contralateral cerebral perfusion pressure in the external (15.0 ± 4.6 versus 15.6 ± 5.3 minutes(-1), P = .15) and internal (15.0 ± 4.8 versus 15.0 ± 4.8 minutes(-1), P = .90) borderzone regions were all similar. Borderzone cerebral perfusion pressure was similar to mean global cerebral perfusion pressure (14.7 ± 4.7 minutes(-1), P ≥ .29). Perihematoma cerebral perfusion pressure did not differ between blood pressure treatment groups (13.9 ± 5.5 minutes(-1) versus 14.8 ± 3.4 minutes(-1), P = .38) or vary with mean arterial pressure (r = -0.08, [-0.10, 0.05]).

CONCLUSIONS

Perihematoma cerebral perfusion pressure is maintained despite increased cerebrovascular resistance and reduced cerebral blood flow. Aggressive antihypertensive therapy does not affect perihematoma or borderzone cerebral perfusion pressure. Maintenance of cerebral perfusion pressure provides physiologic support for the safety of blood pressure reduction in intracerebral hemorrhage.

Statin therapy does not affect the radiographic and clinical profile of patients with TIA and minor stroke

BACKGROUND AND PURPOSE

Acute statin therapy improves neurologic outcome and diminishes infarct growth in animal models of stroke. Clinical studies suggest that premorbid and early statin use is associated with improved outcome after major stroke. We studied the association between statin therapy and radiographic and clinical outcomes in patients with high-risk TIA and minor stroke.

MATERIALS AND METHODS

Patients with high-risk TIA and minor stroke (NIHSS ≤3) were prospectively enrolled within 24 hours of symptom onset. Patients were followed clinically for 3 months, and a subset had a repeat MR imaging at 90 days.

RESULTS

Of 418 patients, 23% were prescribed statins before their stroke. Statins were continued in 20% and initiated in 42%. Patients on prior statin therapy were older and more hypertensive, treated with aspirin, and more likely to have symptomatic carotid disease compared with those not on statin. Adjusting for these differences, prior statin treatment was not associated with DWI positivity (adjusted OR = 1.3; 95% CI, 0.77-2.1; P = .32) or smaller median baseline infarct volume, 1.1 mL (interquartile range = 4) versus 1 mL (interquartile range = 2.5; P = .56). Early or continued treatment with statins did not improve the risk of clinical deterioration (adjusted OR = 0.66; 95% CI, 0.27-1.6; P = .35) or poor functional outcome at 3 months (adjusted OR = 0.66; 95% CI, 0.35-1.24; P = .19).

CONCLUSIONS

Prestroke or early-stroke statin therapy was not associated with a reduction in the number of DWI lesions, infarct volume, or improved clinical or functional outcome at 3 months. The effect of acute statin treatment in patients with ischemic stroke/TIA remains unclear and needs further investigation.

DWI reversal is associated with small infarct volume in patients with TIA and minor stroke

BACKGROUND AND PURPOSE

More than half of patients with TIA/minor stroke have ischemic lesions on early DWI, which represent irreversibly damaged tissue. The presence and volume of DWI lesions predict early deterioration in this population. We aimed to study the rate and implications of DWI reversal in patients with TIA/minor stroke.

MATERIALS AND METHODS

Patients with TIA/minor stroke were prospectively enrolled and imaged within 24 hours of onset. Patients were followed for 3 months with repeat MR imaging either at day 30 or 90. Baseline DWI/PWI and follow-up FLAIR final infarct volumes were measured.

RESULTS

Of 418 patients included, 55.5% had DWI and 37% had PWI (time-to-peak of the impulse response ≥2 seconds' delay) lesions at baseline. The median time from symptom onset to baseline and follow-up imaging was 13.4 (interquartile range, 12.7) and 78.73 hours (interquartile range, 60.2), respectively. DWI reversal occurred in 5.7% of patients. The median DWI lesion volume was significantly smaller in those with reversal (0.26 mL, interquartile range = 0.58 mL) compared with those without (1.29 mL, interquartile range = 3.6 mL, P = .002); 72.7% of DWI reversal occurred in cortically based lesions. Concurrent tissue hypoperfusion (time-to-peak of the impulse response ≥2 seconds) was seen in 36.4% of those with DWI reversal versus 62.4% without (P = .08). DWI reversal occurred in 3.3% of patients with penumbral patterns (time-to-peak of the impulse response ≥6 seconds - DWI) > 0 and in 6.8% of those without penumbral patterns (P = .3). The severity of hypoperfusion, defined as greater prolongation of time-to-peak of the impulse response (≥2, ≥4, ≥6, ≥8 seconds), did not affect the likelihood of DWI reversal (linear trend, P = .147). No patient with DWI reversal had an mRS score of ≥2 at 90 days versus 18.2% of those without reversal (P = .02).

CONCLUSIONS

DWI reversal is uncommon in patients with TIA/minor stroke and is more likely to occur in those with smaller baseline lesions. DWI reversal should not have a significant effect on the accuracy of penumbra definition.

Early stroke risk and ABCD2 score performance in tissue- vs time-defined TIA: a multicenter study

OBJECTIVES

Stroke risk immediately after TIA defined by time-based criteria is high, and prognostic scores (ABCD2 and ABCD3-I) have been developed to assist management. The American Stroke Association has proposed changing the criteria for the distinction between TIA and stroke from time-based to tissue-based. Research using these definitions is lacking. In a multicenter observational cohort study, we have investigated prognosis and performance of the ABCD2 score in TIA, subcategorized as tissue-positive or tissue-negative on diffusion-weighted imaging (DWI) or CT imaging according to the newly proposed criteria.

METHODS

Twelve centers provided data on ABCD2 scores, DWI or CT brain imaging, and follow-up in cohorts of patients with TIA diagnosed by time-based criteria. Stroke rates at 7 and 90 days were studied in relation to tissue-positive or tissue-negative subcategorization, according to the presence or absence of brain infarction. The predictive power of the ABCD2 score was determined using area under receiver operator characteristic curve (AUC) analyses.

RESULTS

A total of 4,574 patients were included. Among DWI patients (n = 3,206), recurrent stroke rates at 7 days were 7.1%(95% confidence interval 5.5-9.1) after tissue-positive and 0.4% (0.2-0.7) after tissue-negative events (p diff < 0.0001). Corresponding rates in CT-imaged patients were 12.8% (9.3-17.4) and 3.0% (2.0-4.2), respectively (p diff < 0.0001). The ABCD2 score had predictive value in tissue-positive and tissue-negative events (AUC = 0.68 [95% confidence interval 0.63-0.73] and 0.73 [0.67-0.80], respectively; p sig < 0.0001 for both results, p diff = 0.17). Tissue-positive events with low ABCD2 scores and tissue-negative events with high ABCD2 scores had similar stroke risks, especially after a 90-day follow-up.

CONCLUSIONS

Our findings support the concept of a tissue-based definition of TIA and stroke, at least on prognostic grounds.

The ASPIRE approach for TIA risk stratification

BACKGROUND

The risk of stroke after transient ischemic attack (TIA) is elevated in the days to weeks after TIA. A variety of prediction rules to predict stroke risk have been suggested. In Alberta a triage algorithm to facilitate urgent access based on risk level was agreed upon for the province. Patients with ABCD2 score ≥ 4, or motor or speech symptoms lasting greater than five minutes, or with atrial fibrillation were considered high risk (the ASPIRE approach). We assessed the ability of the ASPIRE approach to identify patients at risk for stroke.

METHODS

We retrospectively reviewed charts from 573 consecutive patients diagnosed with TIA in Foothills Hospital emergency room from 2002 through 2005. We recorded clinical and event details and identified the risk of stroke at three months.

RESULTS

Among 573 patients the 90-day risk of stroke was 4.7% (95% CI 3.0%, 6.4%). 78% of the patients were identified as high risk using this approach. In patients defined as high risk on the ASPIRE approach there was a 6.3% (95% CI 4.2%, 8.9%) risk of stroke. In patients defined as low risk using the ASPIRE approach there were no recurrent strokes (100% negative predictive value). In contrast, two patients with low ABCD2 scores (ABCD2 score < 4) suffered recurrent strokes.

CONCLUSION

The ASPIRE approach has a perfect negative predictive value in the population in predicting stroke. However, this high sensitivity comes at a cost of identifying most patients as high risk.

Computed tomography and computed tomography angiography findings predict functional impairment in patients with minor stroke and transient ischaemic attack

INTRODUCTION

Abnormalities on acute magnetic resonance imaging predict outcome in minor stroke and transient ischaemic attack patients. We hypothesised that noncontrast computed tomography and computed tomography angiography findings in minor stroke and transient ischaemic attack patients would also predict functional outcome.

METHODS

We analysed consecutive patients with a transient ischaemic attack or a minor stroke with an National Institute of Health Stroke Scale <or=3 who were assessed with a noncontrast computed tomography and CT angiography of the circle of Willis and neck within 24 h of symptom onset. We assessed the association between clinical or imaging features and functional impairment on the modified Rankin Scale (mRS >or=2 ) at 90 days.

RESULTS

Among 457 patients, the median baseline National Institute of Health Stroke Scale score was 1. Median time from symptom onset to noncontrast computed tomography was 278 min (interquartile range 151-505) and median delay from noncontrast computed tomography to CT angiography was 3 min (interquartile range 0-13). At 90 days, 57 patients (12.5%) had a mRS >or=2. Clinical factors that were associated with functional impairment were age >or=60 years (RR 2.05 CI(95) 1.16-3.64) and baseline National Institute of Health Stroke Scale score >0 (RR 3.23 1.72-6.06). All the assessed computed tomography parameters (acute stroke on noncontrast computed tomography and intracranial or extracranial stenosis or occlusion) were individually predictive of functional impairment. A composite computed tomography imaging 'at risk' metric, defined by acute stroke on noncontrast computed tomography, Circle of Willis intracranial vessel occlusion or >or=50% stenosis, extracranial occlusion or >or=50% stenosis, was associated with poorer outcome (RR 2.92 CI(95) 1.81-4.71).

CONCLUSIONS

The presence of an acute stroke on noncontrast computed tomography or an intracranial or extracranial occlusion or stenosis was associated with an increased risk of functional impairment. Multi-modal computed tomography could be used to identify high-risk transient ischaemic attack or minor stroke patients.

CT angiography source images predict final infarct extent in patients with basilar artery occlusion

BACKGROUND AND PURPOSE

The posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) is a 10-point grading system to quantify ischemic changes in the posterior circulation. We analyzed whether pc-ASPECTS on CT angiography (CTA) source images (CTASI) predicted the final infarct extent and hemorrhagic transformation (HT) rate in patients with basilar artery occlusion.

MATERIALS AND METHODS

A pc-ASPECTS score of 10 indicates absence of visible ischemic changes in the posterior circulation, and pc-ASPECTS score of 0 indicates ischemic changes in the midbrain, pons, and bilateral thalami, posterior circulation territories, and cerebellar hemispheres. We retrospectively studied patients with basilar artery occlusion on CTA within 24 hours from symptom onset. We applied pc-ASPECTS to noncontrast CT (NCCT), CTASI, and follow-up images by 3-reader-consensus and assessed HT on follow-up images. We calculated Spearman correlation coefficients and performed linear regression analysis. Final infarct extent and HT rates were compared across dichotomized CTASI pc-ASPECTS groups (>/= 8 vs < 8).

RESULTS

Among 43 patients, median (range) onset to CTA time was 5.0 hours (range, 0.7-24 hours). Pc-ASPECTS on CTASI (r = 0.75; P < .001) but not NCCT (r = 0.29; P = .063) correlated with pc-ASPECTS on follow-up scans. Linear regression demonstrated a significant positive relationship between pc-ASPECTS on CTASI and follow-up scans (R(2) = 0.58; P < 01). Median follow-up pc-ASPECTS was lower in patients with a CTASI pc-ASPECTS < 8 compared with patients with a CTASI pc-ASPECTS of 8 or more, respectively (P < .001). HT rates were 27.3% vs 9.5%, respectively (P = .24). None of 8 patients without thrombolysis had HT on follow-up scans.

CONCLUSIONS

The extent of hypoattenuation on CTASI predicts the final infarct extent in patients with basilar artery occlusion.

Role of recanalization in acute stroke outcome: rationale for a CT angiogram-based "benefit of recanalization" model

BACKGROUND AND PURPOSE

In acute middle cerebral artery (MCA) stroke, CT angiographic (CTA) source images (CTA-SI) identify tissue likely to infarct despite early recanalization. This pilot study evaluated the impact of recanalization status on clinical and radiologic predictors of patient outcomes.

MATERIALS AND METHODS

Of 44 patients undergoing CT/CTA within 6 hours of developing symptoms of proximal MCA ischemia, 19 patients achieved complete proximal MCA (MCA M1) recanalization. Admission National Institutes of Health Stroke Scale (NIHSS) score, onset-to-imaging time, CTA-SI Alberta Stroke Program Early CT Score, MCA M1 occlusion, cerebrovascular collaterals score, and CTA-SI lesion volume were correlated with 3- to 6-month follow-up modified Rankin Scale (mRS). We developed 2 stepwise regression models: one for patients with complete MCA M1 recanalization and one for patients without complete recanalization.

RESULTS

Complete and incomplete recanalization groups had similar median admission NIHSS scores (19 versus 19) and mean onset-to-imaging times (2.3 versus 1.9 hours) but different proportions of patients achieving mRS scores 0-2 (74% versus 40%; P = .04). The only independent predictors of clinical outcome in patients with complete recanalization were onset-to-imaging time and admission CTA-SI lesion volume (total model R(2) = 0.75; P = .01). The only independent predictors of outcome in patients with incomplete recanalization were admission CTA-SI lesion volume and NIHSS score (total model R(2) = 0.66; P = .007).

CONCLUSION

Regardless of recanalization status, admission CTA-SI lesion volume was associated with clinical outcome. Recanalization status did, however, affect which variables in addition to CTA-SI volume significantly impacted clinical outcome: time with complete recanalization and NIHSS with incomplete recanalization. This finding may support the development of a model predicting the potential clinical benefit expected with early successful recanalization.

Acute ischemic lesions of varying ages predict risk of ischemic events in stroke/TIA patients

BACKGROUND

Multiple ischemic lesions identified by diffusion-weighted imaging (DWI) have been shown to predict high risk of future ischemic events. However, the importance of lesion age has not been factored into this risk. Our goal was to evaluate whether the presence of ischemic lesions of varying ages identified by DWI and apparent diffusion coefficient (ADC) suggests a higher risk of future ischemic events.

METHODS

Patients with acute stroke and TIA presenting within 12 hours of symptom onset who had a baseline and 1-month follow-up MRI were enrolled in the study. Acute ischemic lesions were divided into DWI positive with ADC low lesions and DWI positive with ADC normalized lesions. The baseline MRI and the presence of new lesions on the follow-up MRI were analyzed.

RESULTS

A total of 360 patients were prospectively enrolled, and all had appropriate imaging. Two hundred twenty-three were excluded as there were no DWI lesions, they received recombinant tissue plasminogen activator, or they did not have the 30-day follow-up MRI. One hundred seventeen patients had DWI lesions of one age (DWI positive with either ADC low lesions or ADC normalized lesions alone) and 20 had lesions of varying ages (DWI positive lesions with reduced and normalized ADC) on the baseline MRI. Patients with multiple DWI lesions of varying ages were at more risk of having new lesions on the 30-day MRI compared with those having lesions of the same age (relative risk = 3.6; 95% CI 1.9 to 6.8). Multiple DWI lesions of varying ages (odds ratio [OR] 6.6; 95% CI 2.3 to 19.1) and cardioembolic stroke subtype (OR 3.2; 95% CI 1.1 to 8.7) were independently associated with new lesion recurrence by multiple logistic regression analysis.

CONCLUSION

The presence of multiple diffusion-weighted imaging lesions of varying ages suggests very active early recurrence over time and portends a higher early risk of future ischemic events.

Identification of Penumbra and Infarct in Acute Ischemic Stroke Using Computed Tomography Perfusion–Derived Blood Flow and Blood Volume Measurements

BACKGROUND AND PURPOSE

We investigated whether computed tomography (CT) perfusion-derived cerebral blood flow (CBF) and cerebral blood volume (CBV) could be used to differentiate between penumbra and infarcted gray matter in a limited, exploratory sample of acute stroke patients.

METHODS

Thirty patients underwent a noncontrast CT (NCCT), CT angiography (CTA), and CT perfusion (CTP) scan within 7 hours of stroke onset, NCCT and CTA at 24 hours, and NCCT at 5 to 7 days. Twenty-five patients met the criteria for inclusion and were subsequently divided into 2 groups: those with recanalization at 24 hours (n=16) and those without (n=9). Penumbra was operationally defined as tissue with an admission CBF <25 mL x 100 g(-1) x min(-1) that was not infarcted on the 5- to 7-day NCCT. Logistic regression was applied to differentiate between infarct and penumbra data points.

RESULTS

For recanalized patients, CBF was significantly lower (P<0.05) for infarct (13.3+/-3.75 mL x 100 g(-1) x min(-1)) than penumbra (25.0+/-3.82 mL x 100 g(-1) x min(-1)). CBV in the penumbra (2.15+/-0.43 mL x 100 g(-1)) was significantly higher than contralateral (1.78+/-0.30 mL x 100 g(-1)) and infarcted tissue (1.12+/-0.37 mL x 100 g(-1)). Logistic regression using an interaction term (CBFxCBV) resulted in sensitivity, specificity, and accuracy of 97.0%, 97.2%, and 97.1%, respectively. The interaction term resulted in a significantly better (P<0.05) fit than CBF or CBV alone, suggesting that the CBV threshold for infarction varies with CBF. For patients without recanalization, CBF and CBV for infarcted regions were 15.1+/-5.67 mL x 100 g(-1) x min(-1) and 1.17+/-0.41 mL x 100 g(-1), respectively.

CONCLUSIONS

We have shown in a limited sample of patients that CBF and CBV obtained from CTP can be sensitive and specific for infarction and should be investigated further in a prospective trial to assess their utility for differentiating between infarct and penumbra.

Silent ischemia in minor stroke and TIA patients identified on MR imaging

BACKGROUND

In a general population of patients with stroke, the rate of new MRI lesions at 1 week was much higher than expected. With patients with minor stroke and TIA having a higher risk of recurrent clinical events, the authors examined whether patients with minor stroke and TIA also had a high rate of asymptomatic lesions on repeat MRI scanning.

METHODS

Patients with minor stroke and TIA presenting within 12 hours of symptom onset with a NIH Stroke Scale score less than six, who had a baseline MRI and a 1-month follow-up, were enrolled in this study. The follow-up study was examined for new diffusion-weighted imaging lesions as compared to the baseline study. Clinical or MRI factors predicting recurrent lesions were examined.

RESULTS

A total of 143 patients were enrolled and 14 patients (9.8%; 95% CI 5.4, 15.9) had MR evidence of new lesions at 30 days. Six of these new lesions were clinically asymptomatic (42.9%; 95% CI 17.7, 71.1). A trend to increased likelihood of new lesions at 30 days was seen with progressing baseline scan lesion number (none [2.2%], solitary [12.9%], multiple [19.8%]: p = 0.046). Patients whose mechanism of stroke was large artery or cardioembolic were the most likely to have new lesions on follow-up MRI.

CONCLUSION

Minor stroke and TIA are associated with a 10% risk of new lesions on MRI and half of these new lesions are asymptomatic. This risk is lower than seen in more severely affected patients with stroke. Patients with multiple lesions at baseline are at an increased risk for new ischemic lesions.

Adrenal and gonadal contributions to urinary excretion and plasma concentration of epitestosterone in men--effect of adrenal stimulation and implications for detection of testosterone abuse

OBJECTIVE

The ratio of urinary testosterone (T) to epitestosterone (EpiT) is used to detect T abuse in sport. Also, plasma or urinary concentrations of EpiT have been measured to assess testicular steroidogenesis during hormonal male contraception. Further investigations are required to evaluate the relative contributions of the testis and adrenal to EpiT production. To this purpose, we have compared basal urinary EpiT glucuronide and plasma EpiT and the response to synthetic adrenocorticotrophic hormone (ACTH) stimulation between eugonadal and hypogonadal men.

DESIGN AND SUBJECTS

The basal urinary excretion rate of EpiT glucuronide was determined in 34 eugonadal men. Six men, clinically diagnosed as hypogonadal, and 6 out of the 34 eugonadal men previously described, received an intramuscular injection of synthetic ACTH depot (1 mg) at 0800 h on two consecutive days. Blood samples were collected prior to and then at 1.5, 8, 24, 25.5, 32 and 48 h with respect to the first administration (0 h). 24-h urine specimens were collected from 0800 h on days 1 and 2 (baseline) and 3 and 4 (stimulation).

MEASUREMENTS

Plasma EpiT, T and cortisol were measured by RIA and urinary EpiT and T, following glucuronide hydrolysis, by gas chromatography-mass spectrometry (extract combines aglycones with a minor amount of urinary free steroids).

RESULTS

Basal excretion rates of EpiT glucuronide in eugonadal men (range: 62-751 nmol/24 h) were considerably greater than in hypogonadal men (range: 3-34 nmol/24 h). Mean basal plasma EpiT in eugonadal men (1.32 +/- 0.08 nmol/l) were greater than in hypogonadal men (0.68 +/- 0.04 nmol/l). In each group, synthetic ACTH stimulation increased plasma cortisol 4-fold. In eugonadal men, plasma and urinary EpiT were unchanged whereas plasma and urinary T glucuronide decreased in response to ACTH. In hypogonadal patients, ACTH increased plasma and urinary EpiT while plasma T remained unchanged.

CONCLUSION

The testes are the major source of epitestosterone, the adrenal contribution being relatively modest. Following adrenal stimulation, urinary epitestosterone glucuronide increases considerably in hypogonadal men but this increase is masked in eugonadal men because testicular production is probably suppressed by the ACTH-induced rise in cortisol. Activation of the adrenal cortex results in no change or only a small decrease in the urinary T/EpiT ratio in eugonadal men.

The measurement of testosterone in hair

Trace metals and drugs have been measured in hair for a number of years but there are no published papers on the measurement of steroids in human hair. We report here the measurement of testosterone in hair samples taken from men, women and prepubertal children. This was a preliminary investigation to see whether testosterone was detectable in hair and whether concentrations between men and women, and men and prepubertal children were different in line with concentrations of testosterone in the blood. Hair was digested in sodium hydroxide and the testosterone extracted before measurement by radioimmuno- assay. There was a clear difference between testosterone concentrations found in heir collected from men (12.9-77.7 pmol/g) and those found in hair from women (<0.9-10.8 pmol/g). There was no significant difference between the concentrations found in women and children. The authenticity of the testosterone measured was confirmed with GCMS.

Intramuscular administration of 5 alpha-dihydrotestosterone heptanoate: changes in urinary hormone profile

A recommended confirmatory procedure for detecting 5 alpha-dihydrotestosterone (DHT) doping in male athletes proposed the use of the urinary concentration ratio of DHT to epitestosterone (EpiT) as the primary marker and those of 5 alpha-androstane-3 alpha,17 beta-diol (5 alpha-Adiol) to EpiT, luteinizing hormone (LH), and 5 beta-androstane-3 alpha,17 beta-diol (5 beta-Adiol) as secondary markers. Here we investigate the effects on these markers of intramuscular administration of DHT heptanoate (250 mg) to six healthy men. Within 24 h of administration all four markers greatly exceeded the published discrimination limits, remaining above these limits for 10-14 days. All ratios returned to basal values by day 28. In contrast to results after percutaneous administration, 5 beta-Adiol excretion decreased, probably as a consequence of greater suppression of testicular steroidogenesis. Results were largely in agreement with those obtained after percutaneous administration, although probably augmented by the larger dose and the different route of delivery.

Apoptosis induced by gamma-irradiation, but not CD4 ligation, of peripheral T lymphocytes in vivo is p53-dependent

Mice generated by homologous recombination which carry a large deletion of the p53 tumour suppressor gene have a high incidence of spontaneous Thy1-positive thymic lymphoma. Extra-thymic lymphomas are rare. Apoptosis following gamma-irradiation in thymocytes from these animals in vitro is p53-dependent and there is a marked gene dose effect: heterozygotes show partial resistance to irradiation-induced cell death. Apoptosis in the T-cell zones of lymph nodes following in vivo gamma-irradiation was p53-dependent, but the gene dosage effect was less marked than that noted for thymocytes. Apoptosis was induced in vivo by ligation of CD4 on the cell surface following intravenous injection of anti-CD4 monoclonal antibody. Apoptosis was counted in lymph node sections using a semi-automated morphometric system. This showed no evidence of p53 dependency. In contrast to a previous report, which used a different line of p53-deficient mice, splenocytes from p53-null mice did not differ significantly from wild-type cells with respect to in vitro proliferative activity and response to mitogenic stimulation by concanavalin A. This may be due to strain differences. Therefore, whilst p53 has a role in the deletion of lymphocytes which have acquired pathological DNA strand breaks which may lead to mutations, the results of this study imply that p53 is not involved in the control of apoptosis following engagement of surface receptors, nor in response to physiological DNA breaks and normal recombination events during T-cell ontogeny.

Proposed confirmatory procedure for detecting 5 alpha-dihydrotestosterone doping in male athletes

Currently, there is no recommended confirmatory procedure for detecting doping with the anabolic steroid 5 alpha-dihydrotestosterone (DHT) in sportsmen. To develop a method, we determined ratios of hormone concentrations in urine from 120 healthy men and used these to set discrimination limits. These limits were then applied to results for urine specimens from 10 volunteers given DHT percutaneously (125 mg twice daily for 4 days). The ratio of DHT to epitestosterone (EpiT) was chosen as the primary marker of DHT administration, and ratios of 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha-ADIOL) to EpiT, 5 alpha-ADIOL to luteinizing hormone, and 5 alpha-ADIOL to 5 beta-androstane-3 alpha, 17 beta-diol were proposed as secondary markers. To evaluate method suitability, we analyzed 194 samples from sports competitors; results for 193 samples were negative, but the ratios in 1 sample greatly exceeded all the chosen limits. In conclusion, we propose that a test scheme based on our recommendations be considered for implementation in all Olympic drug-testing laboratories.

Proposed confirmatory procedure for detecting 5 alpha-dihydrotestosterone doping in male athletes

Currently, there is no recommended confirmatory procedure for detecting doping with the anabolic steroid 5 alpha-dihydrotestosterone (DHT) in sportsmen. To develop a method, we determined ratios of hormone concentrations in urine from 120 healthy men and used these to set discrimination limits. These limits were then applied to results for urine specimens from 10 volunteers given DHT percutaneously (125 mg twice daily for 4 days). The ratio of DHT to epitestosterone (EpiT) was chosen as the primary marker of DHT administration, and ratios of 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha-ADIOL) to EpiT, 5 alpha-ADIOL to luteinizing hormone, and 5 alpha-ADIOL to 5 beta-androstane-3 alpha, 17 beta-diol were proposed as secondary markers. To evaluate method suitability, we analyzed 194 samples from sports competitors; results for 193 samples were negative, but the ratios in 1 sample greatly exceeded all the chosen limits. In conclusion, we propose that a test scheme based on our recommendations be considered for implementation in all Olympic drug-testing laboratories.

Growth factor modulation of p53-mediated growth arrest versus apoptosis

Irradiation of mammalian cells can cause cell cycle perturbations and apoptotic cell death. We have investigated the modulation of these physiologic end points by growth factor stimulation: irradiation of a murine hematopoietic cell line in the presence of interlekin-3 (IL-3) induces G1 arrest, and irradiation in the absence of IL-3 results in rapid apoptotic cell death. Both of these end points are dependent on p53. Transient removal of IL-3 at the time of irradiation results in decreased clonogenic survival of irradiated cells. The removal of IL-3 results in a failure of the irradiated cells to arrest at the G1 checkpoint, despite induction of p53 and p21WAF1/CIP1, and then the cells enter S-phase where they undergo apoptosis. There are no cytokine-related changes in Bcl-2, Bax, or Bcl-x protein levels that could account for the modulation of G1 arrest versus apoptosis by growth factors. In contrast, rapid p53-independent alterations of basal levels of gadd45 and p21WAF1/CIP1 expression are linked to IL-3 withdrawal, suggesting a potential mechanism for this modulation. Constitutive activation of cytokine-like pathways with induced expression of v-Src or activated c-Raf inhibits the radiation-induced apoptosis and the alterations in p21WAF1/CIP1 and gadd45 expression. These observations suggest additional molecular mechanisms that can contribute to the development of radioresistance and resistance to apoptosis during tumorigenesis and provide an explanation for the observed lack of p53 mutations in some tumor types. In addition, these data suggest that oncogenic changes occurring during multistep tumorigenesis could be classified as those that either enhance or decrease apoptosis tendencies.