Citations

The microtubule-binding protein tau has been implicated in the pathogenesis of Alzheimer's disease and related disorders. However, the mechanisms underlying tau-mediated neurotoxicity remain unclear. We created a genetic model of tau-related neurodegenerative disease by expressing wild-type and mutant forms of human tau in the fruit fly Drosophila melanogaster . Transgenic flies showed key features of the human disorders: adult onset, progressive neurodegeneration, early death, enhanced toxicity of mutant tau, accumulation of abnormal tau, and relative anatomic selectivity. However, neurodegeneration occurred without the neurofibrillary tangle formation that is seen in human disease and some rodent tauopathy models. This fly model may allow a genetic analysis of the cellular mechanisms underlying tau neurotoxicity.

Abstract ATR (ataxia telangiectasia and Rad3-related) function is necessary for the proper response to commonly used chemotherapeutic agents. Heterozygous truncating mutations in exon 10 of the ATR gene have been described in numerous cancers exhibiting microsatellite instability. We show that truncating mutations of ATR are capable of acting in a dominant-negative manner to abrogate ATR-dependent Chk1 phosphorylation and cell-cycle arrests after DNA damage. In addition, endometrial cell lines harboring ATR mutations are defective for ATR-dependent responses. These findings imply that ATR mutations play an important role in the development and clinical behavior of a subset of microsatellite instability–positive endometrial, colon, and stomach cancers.

Neurofibrillary tangles (NFTs) are the most common intraneuronal inclusion in the brains of patients with neurodegenerative diseases and have been implicated in mediating neuronal death and cognitive deficits. Here, we found that mice expressing a repressible human tau variant developed progressive age-related NFTs, neuronal loss, and behavioral impairments. After the suppression of transgenic tau, memory function recovered, and neuron numbers stabilized, but to our surprise, NFTs continued to accumulate. Thus, NFTs are not sufficient to cause cognitive decline or neuronal death in this model of tauopathy.

OBJECTIVE To review the characteristics and determine treatment outcomes of pediatric dermoid cysts. STUDY DESIGN AND SETTING Retrospective review of the presentation, diagnosis, treatment, and outcomes of all pediatric dermoid cysts of the head and neck examined between 1980 and 2002 at Mayo Clinic. RESULTS Forty‐nine patients (59% girls) had a dermoid cyst of the head and neck. The median age at diagnosis was 22 months. The most common presenting sign was a palpable mass, noted in 100% of patients. During evaluation, approximately 25 patients (51%) had imaging studies. The most common location of the cysts was periorbital (61%), followed by the neck (18%; including 1 submental cyst). Various surgical approaches were chosen. In 2 patients (4%), the dermoid cyst had an intracranial extension. Only 1 patient experienced recurrence. The median pathologic diameter of the cysts was 1.2 cm. CONCLUSIONS Dermoid cysts are unusual neoplasms that often present in childhood, with the orbit being the area most commonly affected in the head and neck region. Imaging studies help rule out an intracranial or intraorbital extension. With complete excision, recurrence is unusual. SIGNIFICANCE Our review will assist both primary care physicians and subspecialists in diagnosing and treating dermoid cysts.

Neurofibrillary tangles composed of hyperphosphorylated, aggregated tau are a common pathological feature of tauopathies, including Alzheimer's disease. Abnormal phosphorylation of tau by kinases or phosphatases has been proposed as a pathogenic mechanism in tangle formation. To investigate whether kinase inhibition can reduce tauopathy and the degeneration associated with it in vivo , transgenic mice overexpressing mutant human tau were treated with the glycogen synthase kinase-3 (GSK-3) inhibitor lithium chloride. Treatment resulted in significant inhibition of GSK-3 activity. Lithium administration also resulted in significantly lower levels of phosphorylation at several epitopes of tau known to be hyperphosphorylated in Alzheimer's disease and significantly reduced levels of aggregated, insoluble tau. Administration of a second GSK-3 inhibitor also correlated with reduced insoluble tau levels, supporting the idea that lithium exerts its effect through GSK-3 inhibition. Levels of aggregated tau correlated strongly with degree of axonal degeneration, and lithium-chloride-treated mice showed less degeneration if administration was started during early stages of tangle development. These results support the idea that kinases are involved in tauopathy progression and that kinase inhibitors may be effective therapeutically.

Background and Purpose— Following publication of concerns about the results of the National Institute of Neurological Disorders and Stroke (NINDS) intravenous tissue plasminogen activator (t-PA) in acute stroke treatment trial, NINDS commissioned an independent committee “to address whether there is concern that eligible stroke patients may not benefit from t-PA given according to the protocol used in the trials and, whether the subgroup imbalance (in baseline stroke severity) invalidates the entire trial.” Methods— The original NINDS trial data were reanalyzed to assess the t-PA treatment effect, the effect of the baseline imbalance in stroke severity between the treatment groups on the t-PA treatment effect, and whether subgroups of patients did not benefit from receiving t-PA. Results— A clinically important and statistically significant benefit of t-PA therapy was identified despite subgroup imbalances in baseline stroke severity and an increased incidence of symptomatic intracerebral hemorrhage in t-PA treated patients. The adjusted t-PA to placebo odds ratio (OR) of a favorable outcome was 2.1 (95% CI, 1.5 to 2.9). Although these exploratory analyses found no statistical evidence that the t-PA treatment effect differed among patient subgroups, the study was not powered to detect subgroup treatment differences. Conclusions— These findings support the use of t-PA to treat patients with acute ischemic stroke within 3 hours of onset under the NINDS t-PA trial protocol. Health professionals should work collaboratively to develop guidelines to ensure appropriate use of t-PA in acute ischemic stroke patients.