MR relaxation times in human brain: measurement at 4 T

PURPOSE: To determine the values for relaxation times in human brain for magnetic resonance (MR) imaging at 4 T. MATERIALS AND METHODS: T1 measurements were made with a progressive saturation sequence, an implementation of the Look-Locker sequence, and an inversion-recovery (IR) interleaved echo-planar imaging (IEPI) sequence. T2 measurements were made with a standard spin-echo (SE) sequence and an SE IEPI sequence. RESULTS: The T1 measurements yielded values of 1,724 msec +/- 51 for gray matter, 1,043 msec +/- 27 for white matter, and 4,550 msec +/- 800 msec for cerebrospinal fluid. The deep gray matter regions had T1 values of 1,458 +/- 38 (caudate nucleus) and 1,372 +/- 60 (putamen). The T2 measurements yielded results of 63 msec +/- 6.2 for gray matter and 49.8 msec +/- 2.2 for white matter. CONCLUSION: The T1 values measured at 4 T show a higher value than predicted from extrapolation at lower field strengths. The T2 measurements showed a slight decrease in values over those measured at lower-field strength. The gain in signal-to-noise ratio from the higher field strength may be substantially offset by these altered relaxation time values to a degree that is sequence dependent.     

Metabolic responses of the neonatal rabbit brain to hydrocephalus and shunting

The metabolic changes that occur in the neonatal brain as a result of hydrocephalus, and the response to ventriculoperitoneal shunting, vary with the maturational stage of the brain. In this study, local glucose utilization (LCMRglu) and oxidative metabolic capacity were estimated using 2-deoxyglucose autoradiography and cytochrome oxidase histochemistry, respectively. Hydrocephalus was induced in rabbit pups via intracisternal kaolin injections at 4-6 days of age. Shunting occurred at 19-26 days of age and the animals were sacrificed at ages ranging from 33 to 331 days. In normal animals there was a high glucose demand early in life which showed a decrease at about 60 days of age. In rabbits sacrificed prior to 60 days of age the controls showed the highest LCMRglu with significant decreases in both the hydrocephalic and shunted animals. After 60 days of age the shunted animals had higher LCMRglu than both the hydrocephalic and control subjects. Oxidative metabolic capacity peaked before 50 days of age in normal animals. At the youngest age, both the hydrocephalic and shunted animals showed higher cytochrome oxidase density rates than the control rabbits. In the older group, the hydrocephalic animals remained high while the shunted animals approximated the control densities. Neither the changes seen in the LCMRglu nor the oxidative metabolic capacity were correlated with changes in cell packing density or increased intracranial pressure. These data suggest that when the brain is compromised by hydrocephalus, there is an initial compensatory increase in oxidative metabolic capacity. The development of the glycolytic pathway appears to be retarded by hydrocephalus, but with shunting and the passage of time, the LCMRglu rebounds to levels above that of controls.     

Interest among gay/bisexual men in greater Boston in participating in clinical trials of preventive HIV vaccines

To estimate interest in HIV preventive vaccine trials, we administered questionnaires to two otherwise demographically similar cohorts of older (mean 40 years) and younger (mean 23 years) gay men in Boston. Questionnaire responses were linked to concurrent behavioral and demographic data. Univariate analyses, performed separately for older and younger cohorts, identified factors that distinguished participants who were "very interested" from those who were "not at all interested". Multivariate logistic regression analyses were used to adjust for confounding. Among all 630 participants, 215 (34%) were "not at all" interested in participating, 306 (49%) were "somewhat" interested, and 102 (16%) were "very" interested. Older men were significantly more likely than younger men to be "very" interested and less likely to be "not at all interested." Among both older and younger men, perceived peer willingness to enroll in vaccine trials predicted interest after adjusting for confounding. Among older men, optimism about success in vaccine development also predicted interest. In the younger cohort, men recruited in community settings (e.g., bars, nightclubs) were more interested in vaccine trial participation than were those recruited by outreach workers and word of mouth on college campuses. Vaccine-induced seroconversion evoked significant concern.     

CP-135,807, a selective 5-HT1D agonist: effects in drug discrimination and punishment procedures in the pigeon

CP-135,807 [3-(N-methylpyrrolidin-2R-ylmethyl)-5-(3-nitropyrid-2- yl)amino-1H-indole] binds with high affinity to central 5-HT1D receptors, and in functional studies produces dose-dependent decreases in extracellular serotonin. These and other findings have suggested that CP-135,807 may act as a terminal 5-HT autoreceptor agonist. In an attempt to characterize the behavioral activity of selective 5-HT1D ligands, adult male Carneau pigeons were trained to discriminate IM injections of 0.1 mg/kg CP-135,807 from saline under a two-key, fixed ratio schedule of food-reinforced key pecking. CP-135,807 and the structurally unrelated 5-HT1D agonist CP-286,601 fully and dose-dependently substituted for the training dose. In contrast, little substitution was observed following administration of 8-OH-DPAT, a potent 5-HT1A agonist, the 5-HT1B agonist CP-94,253, or the serotonin reuptake inhibitor sertraline. In addition, the discriminative stimulus produced by CP-135,807 was not blocked by WAY 100,635, a selective 5-HT1A antagonist, but was completely and dose-dependently antagonized by the selective 5-HT1D antagonist, GR 127935. In subjects trained under a multiple schedule of punished and unpunished responding, 8-OH-DPAT produced large increases in punished responding while having little effect on unpunished responding. In contrast, CP-135,807 and CP-94,253 produced no antipunishment effects, while GR 127935 produced modest increases in punished responding. Collectively, these results suggest that CP-135,807 produces centrally mediated psychoactive effects that differ distinctly from those of 5-HT1A agonists.     

Trauma in pregnancy: the role of interpersonal violence

OBJECTIVE: Our purpose was to determine what role interpersonal violence as intentional injury plays in the pregnant trauma victim. STUDY DESIGN: We performed a retrospective review of medical records. RESULTS: During a 9-year period in a single university medical and trauma center, 203 pregnant women were treated for a physically traumatic event. Sixty-four women (31.5%) were victims of intentional injury, in most cases by the husband or boyfriend. Although the mean Injury Severity Score was higher in women with fetal death than in women with successful pregnancy outcomes (7.25 vs 1.74, respectively; p < 0.01), 5 of the 8 women with fetal losses incurred these despite an apparent absence of physical injury (maternal Injury Severity Score = 0). CONCLUSIONS: Interpersonal violence during pregnancy is a frequent and increasingly common cause of maternal injury. The inconsistent relationship between Injury Severity Score and serious fetal injury or death is underscored by the loss of 5 fetuses despite an Injury Severity Score of 0.     

Hydrocephalus

Hydrocephalus may be an acquired or congenital condition. Clinical signs often reflect the level of brain involvement. In young dogs, the presence of a dome-shaped head and/or persistent fontanel are suggestive of hydrocephalus. Ventriculoperitoneal shunting is often used for definitive treatment of hydrocephalus.     

Symmetry of bone mineral density in the hips is not affected by age

To assess the symmetry of bone mineral density (BMD) of the hips, we used dual photon absorptiometry (DPA) to asses BMD in 266 normal Chinese women in the bilateral femoral neck, trochanter and Ward's triangle regions. Linear regression analysis of the results showed excellent correlation between the hips. The correlation coefficients for the femoral neck, trochanter and Ward's triangle regions were 0.899, 0.892 and 0.935 respectively, and the standard errors of the estimate (S.E.E.) were 0.029, 0.027 and 0.022 g cm-2 respectively. Pooling the BMD data of corresponding regions (n = 532), the correlation coefficient was 0.813 for femoral neck versus trochanter, 0.889 for femoral neck versus Ward's triangle, and 0.833 for trochanter versus Ward's triangle. Further analysis showed mean correlation coefficients of 0.854 for elderly subjects (age > or = 65 years, n = 51) and 0.887 for younger subjects (age < 65 years, n = 215). In conclusion, assessment of left or right hip BMD may be used to represent the BMD of the contralateral hip and can reduce both the cost and radiation exposure during mass screening for osteoporosis.     

Paclitaxel (Taxol) as salvage therapy for relapsed ovarian cancer

A retrospective study of 20 patients aged 18 years and younger with ameloblastoma seen over a 10-year period at Harare Central Hospital, Harare, Zimbabwe, was carried out. Males and females were equally affected. The mandible was the most commonly involved bone (95%); the premolar/canine incisor area was commonly affected (69.1%). Incision biopsy was done before wide surgical resection of the involved bone. No currettage or enucleation was used as a mode of treatment. Immediate reconstruction was performed with metallic implants. Twenty percent of the lesions had a unilocular radiologic appearance that resembled a dentigerous cyst. Follow-up was poor.     

Risk factors for delirium tremens development

OBJECTIVE: To identify clinical characteristics associated with inpatient development of delirium tremens so that future treatment efforts can focus on patients most likely to benefit from aggressive therapy. DESIGN: Retrospective cohort study among patients discharged with diagnoses related to alcohol abuse. SETTING: University-affiliated inner-city hospital. PATIENTS/PARTICIPANTS: Two hundred consecutive patients discharged between June 1991 and August 1992 who underwent evaluation and treatment for alcohol withdrawal or detoxification. MEASUREMENTS AND MAIN RESULTS: Mean age was 41.9 years, 85% were male, 57% were white and 84% were unmarried. Forty-eight (24%) of the patients developed delirium tremens during hospitalization. Bivariate analysis indicated that those who developed delirium tremens were more likely to be African-American, unemployed, and homeless, and were more likely to have gone more days since their last drink, and to have concurrent acute medical illness, high admission blood urea nitrogen level and respiratory rate, and low admission albumin level and systolic blood pressure. In multiple logistic regression analyses, patients who developed delirium tremens were more likely to have gone more days since their last drink (odds ratio [OR] 1.3; 95% confidence interval [CI] 1.09, 1.61) and to have concurrent acute medical illness (OR 5.1; 95% CI 2.07, 12.55). These risk factors were combined for assessment of their ability to predict the occurrence of delirium tremens. If no factors were present, 9% developed delirium tremens; if one factor was present, 25% developed delirium tremens; and if two factors were present, 54% developed delirium tremens. CONCLUSIONS: Inpatient development of delirium tremens was common among patients treated for alcohol detoxification or withdrawal and correlated with several readily available clinical variables.