RESUMO
We compared the characteristics of hospitalized and nonhospitalized patients who had coronavirus disease in Atlanta, Georgia, USA. We found that risk for hospitalization increased with a patient's age and number of concurrent conditions. We also found a potential association between hospitalization and high hemoglobin A1c levels in persons with diabetes.
Assuntos
COVID-19 , Diabetes Mellitus , Hemoglobinas Glicadas/análise , Hospitalização/estatística & dados numéricos , Hipertensão , Obesidade , Administração dos Cuidados ao Paciente , Fatores Etários , COVID-19/epidemiologia , COVID-19/psicologia , COVID-19/terapia , Diabetes Mellitus/sangue , Diabetes Mellitus/epidemiologia , Progressão da Doença , Feminino , Georgia/epidemiologia , Humanos , Hipertensão/tratamento farmacológico , Hipertensão/epidemiologia , Masculino , Pessoa de Meia-Idade , Multimorbidade , Obesidade/diagnóstico , Obesidade/epidemiologia , Aceitação pelo Paciente de Cuidados de Saúde , Administração dos Cuidados ao Paciente/métodos , Administração dos Cuidados ao Paciente/normas , Administração dos Cuidados ao Paciente/estatística & dados numéricos , Medição de Risco/métodos , Medição de Risco/estatística & dados numéricos , Fatores de Risco , SARS-CoV-2RESUMO
BACKGROUND: The epidemiological features and outcomes of hospitalized adults with coronavirus disease 2019 (COVID-19) have been described; however, the temporal progression and medical complications of disease among hospitalized patients require further study. Detailed descriptions of the natural history of COVID-19 among hospitalized patients are paramount to optimize health care resource utilization, and the detection of different clinical phenotypes may allow tailored clinical management strategies. METHODS: This was a retrospective cohort study of 305 adult patients hospitalized with COVID-19 in 8 academic and community hospitals. Patient characteristics included demographics, comorbidities, medication use, medical complications, intensive care utilization, and longitudinal vital sign and laboratory test values. We examined laboratory and vital sign trends by mortality status and length of stay. To identify clinical phenotypes, we calculated Gower's dissimilarity matrix between each patient's clinical characteristics and clustered similar patients using the partitioning around medoids algorithm. RESULTS: One phenotype of 6 identified was characterized by high mortality (49%), older age, male sex, elevated inflammatory markers, high prevalence of cardiovascular disease, and shock. Patients with this severe phenotype had significantly elevated peak C-reactive protein creatinine, D-dimer, and white blood cell count and lower minimum lymphocyte count compared with other phenotypes (Pâ <â .01, all comparisons). CONCLUSIONS: Among a cohort of hospitalized adults, we identified a severe phenotype of COVID-19 based on the characteristics of its clinical course and poor prognosis. These findings need to be validated in other cohorts, as improved understanding of clinical phenotypes and risk factors for their development could help inform prognosis and tailored clinical management for COVID-19.
RESUMO
BACKGROUND: Coronavirus disease (COVID-19) can cause severe illness and death. Predictors of poor outcome collected on hospital admission may inform clinical and public health decisions. METHODS: We conducted a retrospective observational cohort investigation of 297 adults admitted to 8 academic and community hospitals in Georgia, United States, during March 2020. Using standardized medical record abstraction, we collected data on predictors including admission demographics, underlying medical conditions, outpatient antihypertensive medications, recorded symptoms, vital signs, radiographic findings, and laboratory values. We used random forest models to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for predictors of invasive mechanical ventilation (IMV) and death. RESULTS: Compared with age <45 years, ages 65-74 years and ≥75 years were predictors of IMV (aORs, 3.12 [95% CI, 1.47-6.60] and 2.79 [95% CI, 1.23-6.33], respectively) and the strongest predictors for death (aORs, 12.92 [95% CI, 3.26-51.25] and 18.06 [95% CI, 4.43-73.63], respectively). Comorbidities associated with death (aORs, 2.4-3.8; Pâ <â .05) included end-stage renal disease, coronary artery disease, and neurologic disorders, but not pulmonary disease, immunocompromise, or hypertension. Prehospital use vs nonuse of angiotensin receptor blockers (aOR, 2.02 [95% CI, 1.03-3.96]) and dihydropyridine calcium channel blockers (aOR, 1.91 [95% CI, 1.03-3.55]) were associated with death. CONCLUSIONS: After adjustment for patient and clinical characteristics, older age was the strongest predictor of death, exceeding comorbidities, abnormal vital signs, and laboratory test abnormalities. That coronary artery disease, but not chronic lung disease, was associated with death among hospitalized patients warrants further investigation, as do associations between certain antihypertensive medications and death.
Assuntos
COVID-19 , Idoso , Hospitalização , Humanos , Pessoa de Meia-Idade , Respiração Artificial , Estudos Retrospectivos , Fatores de Risco , SARS-CoV-2 , Estados UnidosRESUMO
The first reported U.S. case of coronavirus disease 2019 (COVID-19) was detected in January 2020 (1). As of June 15, 2020, approximately 2 million cases and 115,000 COVID-19-associated deaths have been reported in the United States.* Reports of U.S. patients hospitalized with SARS-CoV-2 infection (the virus that causes COVID-19) describe high proportions of older, male, and black persons (2-4). Similarly, when comparing hospitalized patients with catchment area populations or nonhospitalized COVID-19 patients, high proportions have underlying conditions, including diabetes mellitus, hypertension, obesity, cardiovascular disease, chronic kidney disease, or chronic respiratory disease (3,4). For this report, data were abstracted from the medical records of 220 hospitalized and 311 nonhospitalized patients aged ≥18 years with laboratory-confirmed COVID-19 from six acute care hospitals and associated outpatient clinics in metropolitan Atlanta, Georgia. Multivariable analyses were performed to identify patient characteristics associated with hospitalization. The following characteristics were independently associated with hospitalization: age ≥65 years (adjusted odds ratio [aOR] = 3.4), black race (aOR = 3.2), having diabetes mellitus (aOR = 3.1), lack of insurance (aOR = 2.8), male sex (aOR = 2.4), smoking (aOR = 2.3), and obesity (aOR = 1.9). Infection with SARS-CoV-2 can lead to severe outcomes, including death, and measures to protect persons from infection, such as staying at home, social distancing (5), and awareness and management of underlying conditions should be emphasized for those at highest risk for hospitalization with COVID-19. Measures that prevent the spread of infection to others, such as wearing cloth face coverings (6), should be used whenever possible to protect groups at high risk. Potential barriers to the ability to adhere to these measures need to be addressed.
Assuntos
Infecções por Coronavirus/terapia , Hospitalização/estatística & dados numéricos , Pneumonia Viral/terapia , Adolescente , Adulto , Idoso , COVID-19 , Cidades/epidemiologia , Infecções por Coronavirus/epidemiologia , Feminino , Georgia/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/epidemiologia , Fatores de Risco , Adulto JovemRESUMO
SARS-CoV-2, the novel coronavirus that causes coronavirus disease 2019 (COVID-19), was first detected in the United States during January 2020 (1). Since then, >980,000 cases have been reported in the United States, including >55,000 associated deaths as of April 28, 2020 (2). Detailed data on demographic characteristics, underlying medical conditions, and clinical outcomes for persons hospitalized with COVID-19 are needed to inform prevention strategies and community-specific intervention messages. For this report, CDC, the Georgia Department of Public Health, and eight Georgia hospitals (seven in metropolitan Atlanta and one in southern Georgia) summarized medical record-abstracted data for hospitalized adult patients with laboratory-confirmed* COVID-19 who were admitted during March 2020. Among 305 hospitalized patients with COVID-19, 61.6% were aged <65 years, 50.5% were female, and 83.2% with known race/ethnicity were non-Hispanic black (black). Over a quarter of patients (26.2%) did not have conditions thought to put them at higher risk for severe disease, including being aged ≥65 years. The proportion of hospitalized patients who were black was higher than expected based on overall hospital admissions. In an adjusted time-to-event analysis, black patients were not more likely than were nonblack patients to receive invasive mechanical ventilation (IMV) or to die during hospitalization (hazard ratio [HR] = 0.63; 95% confidence interval [CI] = 0.35-1.13). Given the overrepresentation of black patients within this hospitalized cohort, it is important for public health officials to ensure that prevention activities prioritize communities and racial/ethnic groups most affected by COVID-19. Clinicians and public officials should be aware that all adults, regardless of underlying conditions or age, are at risk for serious illness from COVID-19.
Assuntos
Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/terapia , Pneumonia Viral/epidemiologia , Pneumonia Viral/terapia , Adolescente , Adulto , Negro ou Afro-Americano/estatística & dados numéricos , Idoso , Idoso de 80 Anos ou mais , COVID-19 , Estudos de Coortes , Comorbidade , Infecções por Coronavirus/etnologia , Georgia/epidemiologia , Hospitalização/estatística & dados numéricos , Humanos , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/etnologia , Fatores de Risco , Resultado do Tratamento , Adulto JovemRESUMO
The current standard of care for cutaneous leishmaniasis (CL) is organic antimonial compounds, but the administration of these compounds is complicated by a low therapeutic - toxic index, as well as parenteral administration. Thus, there is an urgent need for the development of new and inexpensive therapies for the treatment of CL. In this study, we evaluate the activity of the triphenylmethane (TPM) class of compounds against three species of Leishmania which are pathogenic in humans. The TPM have a history of safe use in humans, dating back to the use of the original member of this class, gentian violet (GV), from the early 20(th) century. Initially, the in vitro efficacy against Leishmania (Viannia) braziliensis, L. (Leishmania) amazonensis and L. (L.) major of 9 newly synthesized TPM, in addition to GV, was tested. Inhibitory concentrations (IC) IC(50) of 0.025 to 0.84 µM had been found in promastigotes in vitro assays. The four most effective compounds were then tested in amastigote intracellular assays, resulting in IC(50) of 0.10 to 1.59 µM. A high degree of selectivity of antiparasitic activity over toxicity to mammalian cells was observed. Afterwards, GV and TPM 6 were tested in a topical formulation in mice infected with L. (L.) amazonensis leading to elimination of parasite burdens at the site of lesion/infection. These results demonstrated that TPM present significant anti-leishmanial activities and provide a rationale for human clinical trials of GV and other TPM. TPM are inexpensive and safe, thus using them for treatment of CL may have a major impact on public health.
Assuntos
Leishmania/efeitos dos fármacos , Leishmaniose Cutânea/tratamento farmacológico , Leishmaniose Cutânea/parasitologia , Compostos de Tritil/farmacologia , Compostos de Tritil/uso terapêutico , Animais , Morte Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Humanos , Espaço Intracelular/efeitos dos fármacos , Espaço Intracelular/parasitologia , Leishmania/citologia , Leishmania/crescimento & desenvolvimento , Leishmania braziliensis/efeitos dos fármacos , Estágios do Ciclo de Vida/efeitos dos fármacos , Camundongos , Peso Molecular , Compostos de Tritil/químicaRESUMO
Alterations in mitochondrial structure and function are a hallmark of cancer cells compared to normal cells and thus targeting mitochondria has emerged as an novel approach to cancer therapy. The mitochondrial thioredoxin 2 (Trx2) system is critical for cell viability, but its role in cancer biology is not well understood. Recently some cationic triphenylmethanes such as brilliant green (BG) and gentian violet were shown to have antitumor and antiangiogenic activity with unknown mechanisms. Here we demonstrate that BG killed cells at nanomolar concentrations and targeted mitochondrial Trx2, which was oxidized and degraded. HeLa cells were more sensitive to BG than fibroblasts. In HeLa cells, Trx2 down-regulation by siRNA resulted in increased sensitivity to BG, whereas for fibroblasts, the same treatments had no effect. BG was observed to accumulate in mitochondria and cause a rapid and dramatic decrease in mitochondrial Trx2 protein. With a redox Western blot method, we found that treatment with BG caused oxidation of both Trx1 and Trx2, followed by release of cytochrome c and apoptosis-inducing factor from the mitochondria into the cytosol. Moreover, this treatment resulted in an elevation of the mRNA level of Lon protease, a protein quality control enzyme in the mitochondrial matrix, suggesting that the oxidized Trx2 may be degraded by Lon protease.
Assuntos
Apoptose/efeitos dos fármacos , Violeta Genciana/farmacologia , Mitocôndrias/metabolismo , Compostos de Amônio Quaternário/farmacologia , Tiorredoxinas/antagonistas & inibidores , Inibidores da Angiogênese/química , Inibidores da Angiogênese/farmacologia , Inibidores da Angiogênese/uso terapêutico , Antineoplásicos/química , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Fator de Indução de Apoptose/análise , Fator de Indução de Apoptose/metabolismo , Cátions/química , Sobrevivência Celular/efeitos dos fármacos , Citocromos c/análise , Citocromos c/metabolismo , Fibroblastos , Violeta Genciana/química , Violeta Genciana/uso terapêutico , Células HeLa , Humanos , Neoplasias/tratamento farmacológico , Oxirredução , Protease La/metabolismo , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/uso terapêutico , RNA Interferente Pequeno/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Tiorredoxinas/biossíntese , Compostos de Tritil/química , Compostos de Tritil/farmacologia , Compostos de Tritil/uso terapêutico , Regulação para CimaRESUMO
Hemangiomas are the most common type of tumor in infants. As they are endothelial cell-derived neoplasias, their growth can be regulated by the autocrine-acting Tie2 ligand angiopoietin 2 (Ang2). Using an experimental model of human hemangiomas, in which polyoma middle T-transformed brain endothelial (bEnd) cells are grafted subcutaneously into nude mice, we compared hemangioma growth originating from bEnd cells derived from wild-type, Ang2+/-, and Ang2-/- mice. Surprisingly, Ang2-deficient bEnd cells formed endothelial tumors that grew rapidly and were devoid of the typical cavernous architecture of slow-growing Ang2-expressing hemangiomas, while Ang2+/- cells were greatly impaired in their in vivo growth. Gene array analysis identified a strong downregulation of NADPH oxidase 4 (Nox4) in Ang2+/- cells. Correspondingly, lentiviral silencing of Nox4 in an Ang2-sufficient bEnd cell line decreased Ang2 mRNA levels and greatly impaired hemangioma growth in vivo. Using a structure-based approach, we identified fulvenes as what we believe to be a novel class of Nox inhibitors. We therefore produced and began the initial characterization of fulvenes as potential Nox inhibitors, finding that fulvene-5 efficiently inhibited Nox activity in vitro and potently inhibited hemangioma growth in vivo. In conclusion, the present study establishes Nox4 as a critical regulator of hemangioma growth and identifies fulvenes as a potential class of candidate inhibitor to therapeutically interfere with Nox function.
Assuntos
Ciclopentanos/farmacologia , Inibidores Enzimáticos/farmacologia , Hemangioma/tratamento farmacológico , NADPH Oxidases/antagonistas & inibidores , Angiopoietina-2/fisiologia , Animais , Células Endoteliais/metabolismo , Hemangioma/patologia , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , NADPH Oxidase 4 , NADPH Oxidases/genética , NADPH Oxidases/fisiologia , Proteínas/genética , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidoresRESUMO
Melanoma is a common malignancy which is poorly responsive to chemotherapy and radiation. One of the major reasons melanoma responds poorly to these modalities is constitutive expression of Akt, which protects against apoptosis. The antidepressant sertraline was found to be a potent cytotoxic agent against A375 human melanoma. To determine the mechanism by which sertraline kills melanoma cells, Western blot analysis of signaling molecules, including phosphorylated Akt, caspase 9 and phospho-p70 S6 kinase was performed. Finally, the effects of sertraline on A375 xenografts in mice were assessed. Sertaline potently inhibited the phosphorylation of Akt, and caused cell death through induction of endoplasmic reticulum in vitro. Sertraline monotherapy demonstrated activity against A375 xenografts in vivo. Akt is a major cause of resistance of melanoma to current therapy. Antidepressants are commonly used to prevent interferon-induced depression. Use of antidepressants that decrease Akt may improve the efficacy of interferon and other therapies against melanoma. Further studies are needed to elucidate whether sertraline acts as an Akt inhibitor in melanoma.
Assuntos
Antineoplásicos/farmacologia , Melanoma/patologia , Proteína Oncogênica v-akt/metabolismo , Sertralina/farmacologia , Animais , Antidepressivos/farmacologia , Proliferação de Células/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Humanos , Masculino , Melanoma/genética , Camundongos , Camundongos Nus , Fosforilação/efeitos dos fármacos , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Targeting death receptor-mediated apoptosis has emerged as an effective strategy for cancer therapy. However, certain types of cancer cells are intrinsically resistant to death receptor-mediated apoptosis. In an effort to identify agents that can sensitize cancer cells to death receptor-induced apoptosis, we have identified honokiol, a natural product with anticancer activity, as shown in various preclinical studies, as an effective sensitizer of death receptor-mediated apoptosis. Honokiol alone moderately inhibited the growth of human lung cancer cells; however, when combined with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), greater effects on decreasing cell survival and inducing apoptosis than TRAIL alone were observed, indicating that honokiol cooperates with TRAIL to enhance apoptosis. This was also true to Fas-induced apoptosis when combined with Fas ligand or an agonistic anti-Fas antibody. Among several apoptosis-associated proteins tested, cellular FLICE-inhibitory protein (c-FLIP) was the only one that was rapidly down-regulated by honokiol in all of the tested cell lines. The down-regulation of c-FLIP by honokiol could be prevented by the proteasome inhibitor MG132. Moreover, honokiol increased c-FLIP ubiquitination. These results indicate that honokiol down-regulates c-FLIP by facilitating its degradation through a ubiquitin/proteasome-mediated mechanism. Enforced expression of ectopic c-FLIP abolished the ability of honokiol to enhance TRAIL-induced apoptosis. Several honokiol derivatives, which exhibited more potent effects on down-regulation of c-FLIP than honokiol, showed better efficacy than honokiol in inhibiting the growth and enhancing TRAIL-induced apoptosis as well. Collectively, we conclude that c-FLIP down-regulation is a key event for honokiol to modulate the death receptor-induced apoptosis.
Assuntos
Apoptose/efeitos dos fármacos , Compostos de Bifenilo/farmacologia , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/antagonistas & inibidores , Lignanas/farmacologia , Receptores de Morte Celular/metabolismo , Compostos de Bifenilo/química , Carcinoma Pulmonar de Células não Pequenas/enzimologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Lignanas/química , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/patologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Ubiquitina/metabolismoRESUMO
Fumagillin is an active amebicide and anti-infective isolated from the fungus Aspergillus fumigatus. Since its characterization in 1951, fumagillin has been studied extensively for its anti-infective properties. Although fumagillin is not approved for systemic use in the USA, this compound has one of the highest efficacies for the treatment of microsporidial infections in HIV-positive patients. Fumagillin does exhibit some side effects that have deterred its acceptance as a viable treatment, but the current body of research on the synthesis of novel analogs of this molecule shows an exciting and promising revival of this drug as both an anti-infective and antiangiogenic agent.
Assuntos
Inibidores da Angiogênese/farmacologia , Anti-Infecciosos/farmacologia , Cicloexanos/farmacologia , Ácidos Graxos Insaturados/farmacologia , Aminopeptidases/antagonistas & inibidores , Aminopeptidases/química , Animais , Cicloexanos/efeitos adversos , Cicloexanos/metabolismo , Cicloexanos/uso terapêutico , Ácidos Graxos Insaturados/efeitos adversos , Ácidos Graxos Insaturados/uso terapêutico , Glicoproteínas/antagonistas & inibidores , Glicoproteínas/química , Humanos , Metionil Aminopeptidases , O-(Cloroacetilcarbamoil)fumagilol , Sesquiterpenos/efeitos adversos , Sesquiterpenos/metabolismo , Sesquiterpenos/farmacologia , Sesquiterpenos/uso terapêuticoRESUMO
Angiomyolipomas are benign tumors of the kidney which express phenotypes of smooth muscle, fat, and melanocytes. These tumors appear with increased frequency in the autosomal dominant disorder tuberous sclerosis and are the leading cause of morbidity in adults with tuberous sclerosis. While benign, these tumors are capable of provoking life threatening hemorrhage and replacement of the kidney parenchyma, resulting in renal failure. The histogenesis of these tumors is currently unclear, although currently, we believe these tumors arise from "perivascular epithelioid cells" of which no normal counterpart has been convincingly demonstrated. Recently, stem cell precursors have been recognized that can give rise to smooth muscle and melanocytes. These precursors have been shown to express the neural stem cell marker NG2 and L1. In order to determine whether angiomyolipomas, which exhibit smooth muscle and melanocytic phenotypes, express NG2 and L1, we performed immunocytochemistry on a cell line derived from a human angiomyolipoma, and found that these cells are uniformly positive. Immunohistochemistry of human angiomyolipoma specimens revealed uniform staining of tumor cells, while renal cell carcinomas revealed positivity only of angiogenic vessels. These results support a novel histogenesis of angiomyolipoma as a defect in differentiation of stem cell precursors.
Assuntos
Angiomiolipoma/química , Angiomiolipoma/etiologia , Biomarcadores Tumorais/metabolismo , Neoplasias Renais/química , Neoplasias Renais/etiologia , Células-Tronco/metabolismo , Angiomiolipoma/patologia , Antígenos/metabolismo , Linhagem Celular Transformada , Transformação Celular Viral , Humanos , Imuno-Histoquímica , Neoplasias Renais/patologia , Complexo Antígeno L1 Leucocitário/metabolismo , Proteoglicanas/metabolismo , Vírus 40 dos Símios/fisiologia , Células-Tronco/citologiaRESUMO
A series of new bisphenol derivatives bearing allylic moieties were synthesized as potential analogs of honokiol and/or magnolol. Certain compounds exhibited specific anti-proliferation activity against SVR cells and moderate anti-HIV-1 activity in primary human lymphocytes. Compound 5h was the most potent compound and its anti-tumor activity was evaluated in vivo.
Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Antivirais/síntese química , Antivirais/farmacologia , Compostos de Bifenilo/química , Lignanas/química , Compostos de Bifenilo/farmacologia , HIV-1/efeitos dos fármacos , Lignanas/farmacologia , Estrutura MolecularRESUMO
Tuberous sclerosis (TS) is a common autosomal dominant disorder caused by loss or malfunction of hamartin (tsc1) or tuberin (tsc2). Many lesions in TS do not demonstrate loss of heterozygosity for these genes, implying that dominant negative forms of these genes may account for some hamartomas and neoplasms in TS. To test this hypothesis, we expressed a dominant negative allele of tuberin (DeltaRG) behind the cytomegalovirus promoter in NIH3T3 cells and transgenic mice. This allele binds hamartin but has a deletion in the C terminus of tuberin, leading to constitutive activation of rap1 and rab5/rabaptin. Expression of DeltaRG in NIH3T3 cells led to a strong induction of reactive oxygen species, induction of vascular endothelial growth factor, and malignant transformation in vivo. Expression of DeltaRG driven by the constitutive cytomegalovirus promoter led to high level expression in all murine tissues examined, including skin, kidney, liver, and brain. Surprisingly, mice expressing the DeltaRG transgene developed a fibrovascular collagenoma in the dermis, which closely resembles the Shagreen patch observed in human patients with TS. In addition, numerous small subpial collections of external granule cells in the cerebellum were observed, which may be the murine equivalent of subependymal giant cell astrocytomas or tubers commonly seen in TS patients. Thus, expression of a dominant negative tuberin in multiple tissues can lead to a tissue-specific phenotype resembling some of the findings in human TS. Our data are the first to demonstrate that specific signaling abnormalities underlie specific hamartomas in a model of a human genetic disorder.