Temperature is the evil twin: effects of increased temperature and ocean acidification on reproduction in a reef fish.

Reproduction in many organisms can be disrupted by changes to the physical environment, such as those predicted to occur during climate change. Marine organisms face the dual climate change threats of increasing temperature and ocean acidification, yet no studies have examined the potential interactive effects of these stressors on reproduction in marine fishes. We used a long-term experiment to test the interactive effects of increased temperature and CO2 on the reproductive performance of the anemonefish, Amphiprion melanopus. Adult breeding pairs were kept for 10 months at three temperatures (28.5°C [+0.0°C], 30.0°C [-1.5°C] and 31.5°C [+3.0°C]) cross-factored with three CO2 levels (a current-day control [417 µatm] and moderate [644 µatm] and high [1134 µatm]) treatments consistent with the range of CO2 projections for the year 2100. We recorded each egg clutch produced during the breeding season, the number of eggs laid per clutch, average egg size, fertilization success, survival to hatching, hatchling length, and yolk provisioning. Adult body condition, hepatosomatic index, gonadosomatic index, and plasma 17ß-estradiol concentrations were measured at the end of the breeding season to determine the effect of prolonged exposure to increased temperature and elevated. CO2 on adults, and to examine potential physiological mechanisms for changes in reproduction. Temperature had by far the stronger influence on reproduction, with clear declines in reproduction occurring in the +1.5°C treatment and ceasing altogether in the +3.0°C treatment. In contrast, CO2 had a minimal effect on the majority of reproductive traits measured, but caused a decline in offspring quality in combination with elevated temperature. We detected no significant effect of temperature or Co2 on adult body condition or hepatosomatic index. Elevated temperature had a significant negative effect on plasma 17ß-estradiol concentrations, suggesting that declines in reproduction with increasing temperature were due to the thermal sensitivity of reproductive hormones rather than a reduction in energy available for reproduction. Our results show that elevated temperature exerts a stronger influence than high CO2 on reproduction in A. melanopus. Understanding how these two environmental variables interact to affect the reproductive performance of marine organisms will be important for predicting the future impacts of climate change.

Rapid assessment of postural instability in Parkinson's disease (RAPID): a pilot study.

BACKGROUND: The Fahn's pull (or retropulsion) test is an item in the motor section of the Unified Parkinson's Disease Rating Scale, which is used almost exclusively to classify postural instability in Parkinson's disease (PD). However, the test is hard to standardize and is often performed incorrectly, making it hard to interpret. Moreover, it may not be safe to administer in patients who experience pain in the shoulders, neck, trunk and/or lower extremities. Identifying and grading postural instability in PD without requiring a physical challenge would not only be useful for the clinician but would assist patients and caregivers in its recognition. We propose the use of the rapid assessment of postural instability in Parkinson's disease (RAPID) questionnaire as a non-physical assessment tool. METHODS: We determined the associations between the pull test and items on a risk-assessment questionnaire that consisted of three parts: activities of daily living, fear of falling, and frequency of falling. RESULTS: Significant correlations were found between the pull test and the predictor variables, which ranged between 0.51 and 0.56 whilst the correlations amongst the predictor variables ranged between 0.58 and 0.70. The three parts of the questionnaire, when used in combination, produced a 96% sensitivity in the classification of postural instability. CONCLUSIONS: The RAPID questionnaire can be used as an adjunct to the pull test or solely if the pull test is contraindicated. It may also be possible to administer the questionnaire via the telephone or Internet. It is hoped that the rapid identification of postural instability would lead to fewer falls.

Resources for genetic management and genomics research on non-human primates at the National Primate Research Centers (NPRCs).

The National Primate Research Centers (NPRCs) established Working Groups (WGs) for developing resources and mechanisms to facilitate collaborations among non-human primate (NHP) researchers. Here we report the progress of the Genome Banking and the Genetics and Genomics WGs in developing resources to advance the exchange, analysis and comparison of NHP genetic and genomic data across the NPRCs. The Genome Banking WG has established a National NHP DNA bank comprising 1250 DNA samples from unrelated animals and family trios from the 10 NHP species housed within the NPRC system. The Genetics and Genomics WG is developing SNP arrays that will provide a uniform, highly informative, efficient and low-cost method for rhesus and long-tailed macaque genotyping across the eight NPRCs. This WG is also establishing a Biomedical Informatics Research Network-based portal for shared bioinformatics resources including vital statistics, genotype and population data and information on the National NHP DNA bank.

Rhesus monkey tryptophan hydroxylase-2 coding region haplotypes affect mRNA stability.

Tryptophan hydroxylase-2 (TPH2) synthesizes neuronal 5-HT and its genetic variance is associated with numerous behavioral traits and psychiatric disorders. This study characterized the functional significance of two nonsynonymous single nucleotide polymorphisms (SNPs) (C74A and G223A) in rhesus monkey TPH2 (mTPH2). Four haplotypes of mTPH2 were cloned into pcDNA3.1 and stably transfected into PC12 cells. The levels of mTPH2 mRNA and protein were assessed by quantitative real-time PCR and Western blot, respectively, while the intracellular 5-HT was measured by enzyme-linked immunosorbent assay (ELISA). The variant A-A haplotype showed significantly higher levels of mTPH2 mRNA and protein, as well as significantly higher 5-HT production than the wild-type C-G haplotype, while the other two variant haplotypes (C-A and A-G) also tended to produce more 5-HT than C-G haplotype when stably expressed in PC12 cells. Both C74A and G223A were predicted to change mRNA secondary structure, and analysis of the mRNA stability showed that the wild-type C-G haplotype mRNA degrades more quickly than mRNAs of the mutant mTPH2 haplotypes in both stable PC12 and transient HEK-293 cells. This study demonstrates that nonsynonymous SNPs in mTPH2 can affect mRNA stability. Our findings provide an additional mechanism by which nonsynonymous SNPs affect TPH2 function, and further our understanding of TPH2 gene expression regulation.

Increased signal in the subarachnoid space on fluid-attenuated inversion recovery imaging associated with the clearance dynamics of gadolinium chelate: a potential diagnostic pitfall.

BACKGROUND AND PURPOSE: Hyperintense CSF in the subarachnoid space (SAS) on fluid-attenuated inversion recovery (FLAIR) imaging has been reported in numerous pathologic conditions, including subarachnoid hemorrhage, meningitis, meningeal carcinomatosis, superior sagittal thrombosis, adjacent tumors, status epilepticus, and stroke. It has also been reported in otherwise healthy patients undergoing anesthesia with supplemental oxygen. We present a series of 11 patients with hyperintense CSF signal intensity in the SAS on FLAIR imaging after previous administration of gadolinium chelate. MATERIALS AND METHODS: Head MR images of patients who had a prior gadolinium-enhanced body, spine, or brain MR imaging and who had increased signal intensity in the SAS on FLAIR images were prospectively and retrospectively reviewed. Correlation was made with the clinical and laboratory findings. RESULTS: Eight of the 11 patients had negative findings on lumbar punctures. Seven patients had either chronic renal insufficiency or acute renal failure, but the remaining 4 had normal renal function. Nine patients had no other significant intracranial abnormalities, and 2 patients had acute infarcts remote from the CSF hyperintensity. One patient had follow-up studies at 24 and 48 hours, documenting resolution of the CSF hyperintensities. CONCLUSION: Given the sharp rise in volume of contrast-enhanced MR imaging studies, it is inevitable that some patients will have undergone a contrast-enhanced MR imaging 24-48 hours before an MR imaging of the brain. The neuroradiologist should be aware that previous administration of gadolinium chelate can cause increased signal intensity in the SAS on FLAIR imaging in patients with or without a history of renal insufficiency and without abnormalities known to disrupt the blood-brain barrier.

Pulsatile luteinizing hormone secretion in normal female mice and in hypogonadal female mice with preoptic area implants.

Pulsatile LH secretion is driven by GnRH, the hypothalamic hormone that is lacking in the hypogonadal mutant mouse. Preoptic area grafts containing GnRH neurons correct many reproductive deficits in hypogonadal mice. In this study we evaluated the pattern of LH secretion in hypogonadal female mice with preoptic area grafts (hpg/POA) and in normal female mice. Normal females were ovariectomized at 10 weeks of age, and hpg/POA mice were ovariectomized 4 months after graft surgery. Three weeks later, all mice received intracardial catheters. The next day, sequential blood samples were obtained every 10 min for 4 h from the awake, freely moving mice. At ovariectomy, normal and hpg/POA ovarian weights were 8.6 +/- 0.9 and 7.1 +/- 1.2 mg, respectively. Significant LH pulses were detected in 9 of 10 normal mice and in 9 of 13 hpg/POA mice. Pulse frequency (normal, 0.86 +/- 0.13; hpg/POA, 0.61 +/- 0.13 pulse/h) and interpeak interval (normal, 81.7 +/- 20.3; hpg/POA, 93.2 +/- 24.0 min) were not significantly different (P greater than 0.2), but mean plasma LH levels (normal, 1.07 +/- 0.16 ng/ml; hpg/POA, 0.49 +/- 0.08 ng/ml; P less than 0.005) and mean LH pulse amplitude (normal, 1.92 +/- 0.53; hpg/POA, 0.63 +/- 0.28; P less than 0.05) were significantly lower in the hpg/POA mice. The lower mean LH level and LH pulse amplitude in ovariectomized hpg/POA mice are consistent with the inability of most of these mice to show increased LH secretion after castration. The findings indicate that preoptic area brain grafts are capable of supporting episodic LH release in the hypogonadal mouse and suggest the presence of a functional GnRH pulse generator in the majority of mice with grafts.

FOS expression in gonadotropin-releasing hormone neurons: enhancement by steroid treatment and mating.

Expression of the protooncoprotein FOS is now widely believed to be a marker for neuronal activation. In female rats, a steroid-induced LH surge is accompanied by an increase in FOS-positive GnRH neurons, especially in the region of the organum vasculosum of the lamina terminalis. The present study, conducted in mice, has examined the effects of both steroid hormone treatment and sexual behavior on the expression of FOS in GnRH neurons and their distribution in the central nervous system. Thirty-three ovariectomized mice, each bearing a sc priming capsule of 17 beta-estradiol, were divided into five groups, four of which were treated sequentially with estradiol benzoate (1 microgram) and progesterone (500 micrograms). In females maintained on 17 beta-estradiol only and killed between 1400-1530 h, only 1.3 +/- 0.7% of GnRH neurons contained FOS, while treatment with estradiol benzoate/progesterone increased FOS expression significantly to 31.7 +/- 8.5% in the same time period. In animals killed at 1530-1700 h, FOS expression declined in the absence of a male (13.8 +/- 2.2%) or when the male present in the cage displayed some sexual behavior but did not ejaculate (13.0 +/- 8.6%). Interestingly, the expression of FOS was maintained at a high level (42.3 +/- 11.4%) into the late afternoon in females paired with a reproductively successful (ejaculating) male. There was a positive correlation (r2 = 0.65; P < 0.01) between the level of LH and the number of FOS-positive GnRH neurons. Hence, the expression of FOS in GnRH neurons was enhanced by both a steroid regimen leading to a LH surge and an intense level of mating behavior. Mapping of the GnRH neurons indicates that in animals with the highest level of FOS expression, FOS-positive GnRH neurons were not confined to the region of the organum vasculosum of the lamina terminalis, but were found more widely distributed along the entire rostro-caudal axis of these cells.

Gonadotropin-releasing hormone messenger RNA expression in gonadotroph tumors and normal human pituitary.

Gonadotroph tumors predominantly secrete FSH or free gonadotropin hormone subunits and rarely LH. In contrast to normal gonadotrophs, a subset of tumors synthesize FSH beta-subunit (SU) in excess of alpha-SU, and the cause of gonadotropin hormone-SU biosynthetic defects in these tumors is unknown. Gonadotropin-releasing hormone (GnRH) is known to modify gonadotropin hormone-SU biosynthesis and secretion and may be an important determinant of gonadotroph tumor hormone regulation. Data in experimental animals have demonstrated that endogenous expression of GnRH may occur in the pituitary. We therefore determined whether 1) the GnRH gene is expressed in gonadotroph tumors and normal pituitaries using reverse transcriptase (RT)-PCR; 2) the GnRH receptor gene is co-expressed in gonadotroph tumors; 3) an alternative upstream transcriptional start site on the GnRH gene is utilized; and 4) media from primary cultures of gonadotroph tumors have detectable GnRH immunoreactivity by RIA. GnRH messenger RNA (mRNA) was detected in 10/10 gonadotroph tumors, eight of which expressed GnRH-Receptor mRNA. Both mRNAs were detected in all normal pituitaries studied (n = 6). Six of 10 gonadotroph tumors and 3/6 normal pituitaries had GnRH transcripts derived from the upstream transcriptional start site (5'GnRH). GnRH immunoreactivity was detected in overnight media from 3/3 primary gonadotroph tumor cultures (range: 1.89-5.86pg/mL; limit of detection (LD) = < 1.58pg/mL) but was not detectable in control media. This is the first study to demonstrate endogenous GnRH gene expression in human pituitary adenomas and normal human pituitary tissue. The presence of both GnRH and GnRH-Rc suggest that GnRH may be a paracrine/autocrine regulator of cell function in the pituitary and may affect gonadotroph tumor hormone phenotype.

Somatostatin receptor subtype gene expression in pituitary adenomas.

Somatostatin (SRIF) exerts its diverse biological effects through a family of membrane receptors. In addition to inhibiting GH secretion, SRIF has antiproliferative effects and has been used clinically in the treatment of pituitary tumors. SRIF receptor (SSTR) expression has recently been identified in pituitary adenomas, and it is unknown whether differential expression of SSTR subtypes predicts clinical responses to SRIF analogs. We therefore determined which SSTR subtype messenger RNAs (mRNAs) are expressed in pituitary adenoma phenotypes and in normal human pituitary tissue using reverse transcriptase-polymerase chain reaction and tested whether expression of specific SSTR subtype mRNA is necessary for SRIF inhibition of GH secretion in human somatotroph adenomas in vitro. Expression of SSTR subtypes 1, 2, and 5 mRNA was identified in all pituitary adenoma types and normal pituitary tissue. In contrast, SSTR3 mRNA was detected in only one somatotroph adenoma as well as in control insulinoma tissue, a tissue known to express SSTR3 mRNA, and was not detected in normal pituitary tissue. SSTR4 mRNA was not detected in any human pituitary tissue. To determine whether specific SSTR subtype mRNA expression is required for SRIF inhibition of GH secretion, five somatotroph adenomas were treated with 10(-7) mol/L SRIF in vitro, and significant inhibition of GH release occurred in all adenomas. All five tumors expressed SSTR2 mRNA and SSTR5 mRNA, and three expressed SSTR1 mRNA. The absence of SSTR1 mRNA expression did not affect the ability of SRIF to suppress GH secretion. We conclude that: 1) human pituitary adenomas and normal pituitary express multiple SSTR gene transcripts; 2) SSTR5 mRNA, which has not been reported in other human endocrine tumor types, is expressed in neoplastic and normal pituitary tissue; and 3) SSTR2 mRNA, SSTR5 mRNA, and variable SSTR1 mRNA are expressed in GH-secreting tumors, which are responsive to SRIF in vitro. Further understanding of SSTR gene expression in pituitary adenomas will facilitate our understanding of the pathogenetic mechanisms of tumorigenesis and may provide a rationale for the use of specific SRIF analogs for clinical application.

Liposome-encapsulated tumor necrosis factor-alpha enhances the effects of radiation against human colon tumor xenografts.

Recent reports have shown that tumor necrosis factor-alpha (TNF-alpha) can augment the effects of radiation against certain tumor types. However, the high concentrations of intravenous infusion of TNF-alpha needed to cause tumor regression can induce many systemic side effects. The aims of this study were to determine if TNF-alpha encapsulated in sterically stabilized (Stealth, ALZA Corporation, Mountain View, CA), PEGylated liposomes (SL) augments the antitumor effects of radiation and to compare its efficacy and possible toxicity with free TNF-alpha in the LS174T human colon tumor xenograft model. Nude mice were injected subcutaneously (s.c.) with LS174T cells and treated intravenously (i.v.) with Stealth-liposomal TNF-alpha (SL-TNF-alpha) with and without radiation or TNF-alpha with or without radiation when tumor size was approximately 200 mm(3). In phase 1, a significant decrease (p = 0.047) in tumor growth was observed with radiation at day 21 but not with SL-TNF-alpha or free TNF-alpha alone. By the end of phase 1 (day 27) with continued treatments, the SL-TNF-alpha plus radiation group had significantly smaller tumors (p = 0.044) than those in the free TNF-alpha plus radiation group. In phase 2, where a similar tumor growth reduction pattern was observed, the addition of TNF-alpha to radiation, either as free protein or within SL, increased lymphocyte activation and natural killer (NK) cell numbers in both blood and spleen. The effect was generally more pronounced with SL-TNF-alpha. Systemic toxicity, based on hematologic analyses and body weight, was absent or minimal. Collectively, the data show that pretreatment with SL-TNF-alpha can enhance more effectively, and possibly more safely, the effects of radiation against human colon tumor xenografts than can free TNF-alpha and that the increased antitumor action may involve upregulation of lymphocytes.

MR imaging of progressive downward herniation of the diencephalon.

Some clinicians have challenged the clinicopathologic correlation in patients with brain herniation from acute mass lesions. Earlier studies have questioned the significance of downward displacement of the brainstem in supratentorial herniation. Using recent generation MRI, we studied a patient with an acute hemorrhagic infarction. MRI demonstrated significant compression of the diencephalon with downward displacement of the midbrain and hyperintensity on T2-weighted sequences in the lateral mesencephalon during progression from early diencephalic stage to midbrain upper pons stage of herniation. This is the first intra vitam documentation of diencephalic herniation by MR imaging and confirms rostrocaudal deterioration usually found at autopsy.

Meningeal biopsy in intracranial hypotension: meningeal enhancement on MRI.

Intracranial hypotension is a cause of diffuse enhancement of the pachymeninx with gadolinium, which often is associated with subdural fluid collections. We reviewed the results of meningeal biopsy in six patients with intracranial hypotension and diffuse pachymeningeal enhancement to correlate the MRI findings with histopathologic observations and to explain the abnormalities seen on MRI. Grossly, the dura mater was unremarkable in all patients, as were the leptomeninges, except for one patient with prolonged (18 months) intracranial hypotension in whom the arachnoid was thickened and opaque. Microscopically, the dura mater was entirely normal on its epidural aspect; however, a fairly thin zone of fibroblasts and thin-walled small blood vessels in an amorphous matrix was noted on the subdural aspect. In the patient with longstanding symptoms, diffuse benign arachnoidal cell proliferation was also noted, probably a reaction triggered by longstanding changes in the subdural area, as noted in the five other patients. There was no evidence of inflammation, infection, or metastatic neoplasia. These findings suggest that in intracranial hypotension, the dural-meningeal abnormalities probably represent reactive secondary phenomena, likely related to hydrostatic changes in the CSF, and not a primary meningeal process.

Absent pachymeningeal gadolinium enhancement on cranial MRI despite symptomatic CSF leak.

CSF leak is recognized to cause orthostatic headaches and diffuse pachymeningeal gadolinium enhancement (DPMGE) on MRI. We report six patients with typical symptoms and documented CSF leaks without DPMGE. Two had normal meninges from the onset; one initially had normal meninges, but subsequently DPMGE developed. In three, the initially noted DPMGE resolved while they were still symptomatic with documented continued CSF leaks. Absent DPMGE does not rule out CSF leak. When clinical manifestations suggest this disorder, additional diagnostic studies should be pursued.

Sarcomas of calvarial bones: rare remote effect of radiation therapy for brain tumors.

After latent periods lasting from 7 to 23 years, sarcomas of the calvaria developed in four patients who had received radiation therapy for a brain tumor. There was no evidence of bony disease before radiation therapy, and the sarcoma (two fibrosarcomas and two osteosarcomas) developed in the field of radiation in all four patients. One of these four died during resection of the tumor, two survived for either 7 or 21 months after diagnosis of the sarcoma, and one was alive at 23 months after the clinical appearance of the sarcoma. The latter patient has had two resections and extensive chemotherapy. Distant metastases were not present in any of the patients. Sarcoma of the calvarial bones is a serious but rare remote effect of radiation therapy for brain tumors.

Schizencephaly: a clinical and CT study.

Schizencephaly is a primary developmental defect of the brain, presumably caused by failure of formation of the cerebral mantle in the regions of the cerebral fissures. Identification has usually been at autopsy, in association with severe neurologic abnormalities. We identified the characteristic features of schizencephaly on CTs in 11 patients. Age at detection ranged from an infant at 8 months to a 30-year-old adult. Clinical abnormalities varied from mild to severe, including developmental delays and retardation, microcephaly, focal or generalized motor abnormalities, and seizures. CT findings included cerebral clefts, infolding of cortical gray matter along the clefts, an abnormal ventricular system, and other associated cerebral anomalies.

Right aortic arch with isolation of the left subclavian artery: case report and review of the literature.

Of the right aortic arch anomalies, a right arch with isolation of the left subclavian artery is the least common. Herein we describe a 52-year-old woman in whom this anomaly was discovered during cerebral angiography for evaluation of a giant symptomatic intracavernous carotid aneurysm. Isolation of the left subclavian artery may be suggested in a patient with a right arch in whom the blood pressure or pulse in the left upper extremity is diminished. Although the isolated left subclavian artery produces the hemodynamic alterations of a subclavian steal, review of the 39 cases reported in the literature revealed only 5 patients with symptoms suggestive of vertebrobasilar insufficiency and 5 patients with weakness of the left upper extremity. Although the patient we describe had no known heart disease, congenital heart disease was present in 23 of the 39 reported cases (59%), tetralogy of Fallot occurring most frequently.

Syndrome of orthostatic headaches and diffuse pachymeningeal gadolinium enhancement.

OBJECTIVE: To characterize clinical and imaging features, biopsy findings, etiologic factors, and outcome in the syndrome of intracranial hypotension, headaches, and diffuse pachymeningeal gadolinium enhancement on magnetic resonance imaging (MRI). MATERIAL AND METHODS: We describe our experience with 26 consecutive patients with orthostatic headaches and diffuse pachymeningeal gadolinium enhancement, for all of whom clinical, imaging, and follow-up data were available. For 10 patients who had undergone meningeal biopsy, slide material was also reviewed. RESULTS: The 15 men and 11 women ranged from 24 to 76 years of age. All 26 patients had postural headaches; in 22 patients, the headaches were completely alleviated by recumbency. Nausea or emesis, neck pain, horizontal diplopia, changes in hearing, photophobia, upper limb pains or paresthesias, visual blurring, or dysgeusia was noted in some of the patients. Cardinal MRI features were diffuse pachymeningeal gadolinium enhancement (100%), subdural collections of fluid (69%), and evidence of descent of the brain (62%) that sometimes resembled type I Chiari malformation. Cerebrospinal fluid (CSF) opening pressures were 40 mm or less in only 46%. In three patients, CSF pressures were consistently no less than 90 and as high as 130 mm of water. A variable pleocytosis of 5 or more cells/mm3 was noted in 15 patients (more than 40 cells/mm3 in 4 patients). A variable increase in CSF protein was noted in at least one spinal tap in 23 patients. Six patients had overdraining CSF shunts; CSF leak was documented in another 11 patients. Shunt revision or ligation and surgical correction of the leak led to a resolution of the clinical and MRI abnormalities in all cases thus treated. Improvement occurred with epidural blood patch in four patients. Three of the 12 patients treated supportively have remained symptomatic. Histologically, a thin subdural zone of fibroblasts and thin-walled vessels was noted in an amorphous matrix. Two patients with prolonged symptoms had a more pronounced proliferative reaction. CONCLUSION: The syndrome of low-pressure headaches and pachymeningeal gadolinium enhancement is being recognized with increasing frequency. The source of the CSF leak can be demonstrated in many patients. Meningeal abnormalities are likely attributable to decreased CSF volume and hydrostatic CSF pressure changes. The prognosis is typically good.

Pretruncal nonaneurysmal subarachnoid hemorrhage.

OBJECTIVE: To review the diagnostic evaluation and the clinical course of patients with pretruncal nonaneurysmal subarachnoid hemorrhage. MATERIAL AND METHODS: The study population consisted of a consecutive series of patients with a pretruncal nonaneurysmal subarachnoid hemorrhage encountered at Mayo Clinic Rochester during a 6-year interval. We reviewed the clinical manifestations, the neuroimaging characteristics, and the appropriate management. RESULTS: The 15 male and 9 female patients with a pretruncal nonaneurysmal subarachnoid hemorrhage ranged from 3 to 72 years of age (median, 45). Of the 24 patients, 18 had a sudden explosive headache at the time of initial assessment. Ventricular shunting for acute hydrocephalus was indicated in one patient. Neuroimaging studies demonstrated that the center of the hemorrhage was prepontine, and it extended into the interpeduncular or premedullary cisterns. In two patients, a small focal hemorrhage was not noted on an admission computed tomographic scan but was identified on repeated study. A second four-vessel cerebral angiogram, obtained in most patients, showed normal findings in four patients who had had cerebral vasospasm on the first study. In one patient, moderate cerebral vasospasm was found on the second angiogram. No patient had rebleeding. One patient had transient dysphasia associated with cerebral vasospasm after cerebral angiography. Two patients had a family history of aneurysmal subarachnoid hemorrhage. CONCLUSION: The excellent outcome in patients with pretruncal nonaneurysmal subarachnoid hemorrhage is in distinct contrast to the overall somber outcome associated with aneurysmal subarachnoid hemorrhage. A ruptured aneurysm of the posterior circulation may mimic a pretruncal nonaneurysmal subarachnoid hemorrhage and should be excluded on the basis of a technically satisfactory cerebral angiogram.

Magnetic resonance imaging of the spine.

Magnetic resonance (MR) imaging offers the advantages of multiplanar capabilities, physiologic as well as anatomic imaging, and some tissue specificity. Since mid-1985, we have performed more than 2,800 MR examinations of the spine, and gadolinium has been used as a contrast agent in many MR studies since its release by the Food and Drug Administration last year. Although MR imaging has been promoted as the procedure of choice for all clinical indications, on the basis of our experience myelography still plays an important role in the imaging of many spinal disorders, including disk disease. Some pathologic conditions such as intraspinal vascular malformations and leptomeningeal metastatic lesions are best imaged by myelography. MR studies have been most useful in evaluating intraspinal neoplasms, spinal cord parenchymal lesions, infections, congenital abnormalities, and "postoperative failed back syndromes."

Cerebral tuberous sclerosis: postmortem magnetic resonance imaging and pathologic anatomy.

We conducted postmortem magnetic resonance imaging (MRI) studies of five brains from patients with a clinical and pathologic diagnosis of tuberous sclerosis. Areas of prolonged T1 and T2 relaxation could easily be identified within the white matter subjacent to the cortical tubers despite formalin fixation and storage. The signal changes were identical to those reported in living patients with the disease. The detection of cortical tubers by MRI in two patients who were 34 and 35 years of age, respectively, at the time of death suggests that the signal changes on MRI are less affected by aging than are the low-attenuation changes on computed tomography, which are rarely identified in patients older than 27 years of age. Once the changes caused by fixation of tissues are considered, postmortem MRI is a viable investigative tool in studying tuberous sclerosis and other diseases, and it seems to correlate well with the MRI findings in living patients, as well as the gross and histopathologic changes seen at autopsy.