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PubMed2006

New proteins configure a brain drug resistance map in tuberous sclerosis.

Epileptogenic cortical tubers, characterized by dysplastic neurons and balloon cells, is a frequent feature of tuberous sclerosis. In severe tuberous sclerosis-affected individuals, seizures are refractory to medication. Multidrug resistance proteins (multidrug resistance protein-1 [MDR-1] and multidrug resistance-associated protein-1 [MRP-1]) have been found to be highly expressed in epileptogenic cortical tubers. However, two new proteins related to refractoriness in cancer (breast cancer resistance protein and major vault protein) have not been investigated in tuberous sclerosis and refractory epilepsy. On the same brain specimens previously describing the MDR-1 and MRP-1 expression, we investigated retrospectively breast cancer resistance protein and major vault protein by specific monoclonal antibodies and routine immunohistochemistry methods. Breast cancer resistance protein was present in vascular endothelial cells from all the vessels examined in 3 of 3 cases. Major vault protein was detected in only one case, and selectively expressed in several but not all ballooned cells. In epileptogenic cortical tubers, the additional expression of breast cancer resistance protein on vessels and major vault protein in some ballooned cells to the previously demonstrated expression of MDR-1 and MRP-1 (in vessels, astroglia, microglia, neurons, and ballooned cells) configures a brain protein pharmacoresistance map from patients with tuberous sclerosis and refractory epilepsy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Genetic manipulation for enhancing calcium content in potato tuber.

Increased calcium (Ca) in potatoes may increase the production rate by enhancing tuber quality and storability. Additionally, increased Ca levels in important agricultural crops may help ameliorate the incidence of osteoporosis. However, the capacity to alter Ca levels in potato tubers through genetic manipulations has not been previously addressed. Here we demonstrate that potato tubers expressing the Arabidopsis H+/Ca2+ transporter sCAX1 (N-terminal autoinhibitory domain truncated version of CAtion eXchanger 1) contain up to 3-fold more Ca than wild-type tubers. The increased Ca appears to be distributed throughout the tuber. The sCAX1-expressing potatoes have normally undergone the tuber/plant/tuber cycle for three generations; the trait appeared stable through successive generations. The expression of sCAX1 does not appear to alter potato growth and development. Furthermore, increased Ca levels in sCAX1-expressing tubers do not appear to alter tuber morphology or yield. Given the preponderance of potato consumption worldwide, these transgenic plants may be a means of marginally increasing Ca intake levels in the population. To our knowledge, this study represents the first attempts to use biotechnology to increase the Ca content of potatoes.

Antiporters↗
PubMed2002

Tuberous sclerosis: clinicopathologic features and review of the literature.

INTRODUCTION: Tuberous sclerosis is a hamartoneoplastic syndrome, which may involve multiple organ systems. Oral hard tissue manifestations of the syndrome have been described in the literature only as recently as 1955. Patients who presented with clinical manifestations of tuberous sclerosis did not routinely undergo oral surveys to rule out 'lesions', and consequently data on 'lesions' in the maxillofacial complex is scant. Ten cases have been found in the English language literature, which describe maxillofacial 'lesions', which may be tumours, new growths, neoplasms or overgrowths occurring in patients diagnosed with tuberous sclerosis. PURPOSE: To review the literature for all maxillofacial lesions associated with tuberous sclerosis and to present an eleventh case of a patient with a maxillofacial lesion diagnosed as having tuberous sclerosis. RESULTS: Eleven cases were found with maxillofacial fibroblastic lesions associated with tuberous sclerosis. These lesions were all fibrous benign neoplasms found in the maxillofacial bony complex. CONCLUSIONS: Maxillofacial fibroblastic lesions in tuberous sclerosis have various histopathological presentations, some of which may be difficult to differentiate. Consequently, close microscopic examination of these lesions is necessary so that adequate surgical treatment is provided.

Child, Preschool↗
PubMed2002

Tuberous sclerosis-associated lesions of the kidney, brain, and skin are angiogenic neoplasms.

BACKGROUND: Tuberous sclerosis is an autosomal dominant condition characterized by the development of benign neoplasms of the brain, kidney, and skin. Progressive growth and malignant transformation of brain and kidney lesions constitute the major cause of morbidity and mortality in adults with tuberous sclerosis. In addition, growth of skin lesions may be disfiguring to patients. OBJECTIVE: The purpose of this study was to determine whether benign tumors in patients with tuberous sclerosis are angiogenic. METHODS: Brain, kidney, and skin tumors from patients with tuberous sclerosis were stained with CD31, a specific marker of vascular endothelium. In addition, we used Northern blot analysis to demonstrate that renal angiomyolipoma cells express the potent angiogenesis stimulator vascular endothelial growth factor (VEGF). RESULTS: Brain, kidney, and skin neoplasms from patients with tuberous sclerosis are highly angiogenic. Renal angiomyolipoma cells produce the potent angiogenic factor VEGF. CONCLUSION: Benign neoplasms of patients with tuberous sclerosis are highly vascular. Our results provide a rationale for antiangiogenic therapy in the treatment and prevention of tuberous sclerosis-associated neoplasms.

Adult↗
PubMed2003

Response of potato tuber cell division and growth to shade and elevated CO2.

Plants adjust their sink-organ growth rates, development and distribution of dry matter in response to whole-plant photosynthate status. To advance understanding of these processes, potato (Solanum tuberosum L.) plants were subjected to CO(2) and light flux treatments, and early tuber growth was assessed. Atmospheric CO(2) (700 or 350 micro mol mol(-1)) and light flux (shade and control illumination) treatments were imposed at two growth stages: tuber initiation (TI) and tuber bulking (TB). Elevated CO(2) increased accumulation of total net biomass when imposed at both stages, and increased tuber growth rate by about 36 %, but did not increase the number of tubers. Elevated CO(2) increased the number of cells in tubers at both TI and TB stages, whereas shade substantially decreased the number of cells at both stages. Generally, treatments did not affect cell volume or the proportion of nuclei endoreduplicating (repeated nuclear DNA replication in the absence of cell division), but the shade treatment led to a decrease in cell volume at TB and a decrease in endoreduplication at TI. Elevated CO(2) increased, and shade decreased, glucose concentration and soluble invertase activity in the cambial zones at both TI and TB, whereas sucrose concentration and activities of glucokinase, fructokinase, cell-wall-bound invertase and thymidine kinase were unaffected. Modulation of tuber cell division was responsible for much of the growth response to whole-plant photosynthate status, and treatments affected cambial-zone glucose and soluble invertase in a pattern suggesting involvement of a glucose signalling pathway.

Carbohydrate Metabolism↗
PubMed2003

Ultrastructure of potato tubers formed in microgravity under controlled environmental conditions.

Previous spaceflight reports attribute changes in plant ultrastructure to microgravity, but it was thought that the changes might result from growth in uncontrolled environments during spaceflight. To test this possibility, potato explants were examined (a leaf, axillary bud, and small stem segment) grown in the ASTROCULTURETM plant growth unit, which provided a controlled environment. During the 16 d flight of space shuttle Columbia (STS-73), the axillary bud of each explant developed into a mature tuber. Upon return to Earth, tuber slices were examined by transmission electron microscopy. Results showed that the cell ultrastructure of flight-grown tubers could not be distinguished from that of tuber cells grown in the same growth unit on the ground. No differences were observed in cellular features such as protein crystals, plastids with starch grains, mitochondria, rough ER, or plasmodesmata. Cell wall structure, including underlying microtubules, was typical of ground-grown plants. Because cell walls of tubers formed in space were not required to provide support against the force due to gravity, it was hypothesized that these walls might exhibit differences in wall components as compared with walls formed in Earth-grown tubers. Wall components were immunolocalized at the TEM level using monoclonal antibodies JIM 5 and JIM 7, which recognize epitopes of pectins, molecules thought to contribute to wall rigidity and cell adhesion. No difference in presence, abundance or distribution of these pectin epitopes was seen between space- and Earth-grown tubers. This evidence indicates that for the parameters studied, microgravity does not affect the cellular structure of plants grown under controlled environmental conditions.

Environment↗
PubMed2006

Chemically forced dormancy termination mimics natural dormancy progression in potato tuber meristems by reducing ABA content and modifying expression of genes involved in regulating ABA synthesis and metabolism.

The length of potato tuber dormancy depends on both the genotype and the environmental conditions during growth and storage. Abscisic acid (ABA) has been shown to play a critical role in tuber dormancy control but the mechanisms regulating ABA content during dormancy, as well as the sites of ABA synthesis, and catabolism are unknown. Recently, a temporal correlation between changes in ABA content and certain ABA biosynthetic and catabolic genes has been reported in stored field tubers during physiological dormancy progression. However, the protracted length of natural dormancy progression complicated interpretation of these data. To address this issue, in this study the synthetic dormancy-terminating agent bromoethane (BE) was used to induce rapid and highly synchronous sprouting of dormant tubers. The endogenous ABA content of tuber meristems increased 2-fold 24 h after BE treatment and then declined dramatically. By 7 d post-treatment, meristem ABA content had declined by >80%. Exogenous [(3)H]ABA was readily metabolized by isolated meristems to phaseic and dihydrophaseic acids. BE treatment resulted in an almost 2-fold increase in the rate of ABA metabolism. A differential expression of both the StNCED and StCYP707A gene family members in meristems of BE-treated tubers is consistent with a regulatory role for StNCED2 and the StCYP707A1 and StCYP707A2 genes. The present results show that the changes in ABA content observed during tuber dormancy progression are the result of a dynamic equilibrium of ABA biosynthesis and degradation that increasingly favours catabolism as dormancy progresses.

Abscisic Acid↗
PubMed2005

Enhancing vacuolar sucrose cleavage within the developing potato tuber has only minor effects on metabolism.

Modification of tuber carbohydrate metabolism by the tuber-specific expression of a yeast invertase targeted to the cytosol or apoplast has previously been demonstrated to have diverse effects on tuber growth and metabolism. In the current study, we generated plants exhibiting tuber-specific expression of the same enzyme targeted to the vacuole. Enzymatic analysis of the carbohydrate levels of the tuber revealed dramatic decreases in sucrose content coupled with large increases in the levels of glucose and hexose phosphates, but unaltered starch content in the transformants. Analysis of the key enzyme of glycolysis suggests that this pathway is down-regulated in the transformants. Despite these changes in metabolite pools and enzyme activity, few consistent changes could be observed in the estimated metabolic fluxes following incubation of isolated tuber discs in labelled glucose. The analysis of the relative levels of a wide range of metabolites using a gas chromatography-mass spectrometry (GC-MS)-based metabolite profiling method revealed large changes in the levels of fructose and decreases in a range of other sugars, but very few changes in the contents of organic and amino acids. This metabolic profile is remarkably consistent with that obtained following expression of the invertase in the apoplastic compartment, providing circumstantial evidence for the endocytotic trafficking of sugars within potato tuber parenchyma. Finally, the results of this study are compared with those from other plant species and the relative roles of the vacuolar isoform of the enzyme are contrasted.

Carbohydrate Metabolism↗
PubMed1989

Tuberous sclerosis and the relation with renal angiomyolipoma. A genetic study on the clinical aspects.

Renal angiomyolipomas were present in 23 out of a series of 38 patients with proven tuberous sclerosis (60.5%). Multiplicity and bilateral localization of combined renal angiomyolipomas were important differences between this category and the isolated, usually solitary, angiomyolipomas. One of the parents of a patient with tuberous sclerosis had small renal angiomyolipomas without signs of tuberous sclerosis. This indicates that renal angiomyolipomas might be a forme fruste of tuberous sclerosis. Two patients with suspected isolated renal angiomyolipomas proved to have tuberous sclerosis. From this study we can conclude that multiple angiomyolipomas, or a combination of a single renal hamartoma with one of the signs suggestive of tuberous sclerosis, warrant a thorough examination to exclude tuberous sclerosis.

Adolescent↗
PubMed2000

Epilepsy surgery in children with tuberous sclerosis complex: presurgical evaluation and outcome.

PURPOSE: Children with tuberous sclerosis complex (TSC) benefit from excisional surgery if seizures can be localized to a single tuber. We evaluated the role of noninvasive studies to localize the epileptogenic tuber/region (ET/R) and the outcome of focal resection. METHODS: We identified 21 children with TSC, ages 3 months to 15 years (mean 4.8 years). All had video-(electroencephalogram) EEG and magnetic resonance imaging (MRI) scans, and 18 also had ictal single photon emission-computed tomography (SPECT) studies. An ET/R was localized in 17 patients. Thirteen patients underwent resection guided by intraoperative electrocorticography (n = 7) or subdural monitoring (n = 6). RESULTS: Interictal EEG revealed a principal spike focus (PSF) that corresponded to the ET/R in 14 children. In seven, PSFs occurred in rhythmic runs. PSFs were not observed remote from the ET/R. Focal polymorphic slowing and attenuation occurred in the region of the PSF in 11 patients. Sixteen patients demonstrated an ictal focus corresponding to the ET/R. Ictal SPECT revealed focal hyperperfusion correlating with the ET/R in 10 patients. Although the MRIs in all children revealed multiple tubers, the ET/R corresponded to a large discrete tuber in 8 patients and a calcified tuber in 13 patients. Patchy calcified tubers were also seen elsewhere in six patients. At a mean follow-up of 26 months, 9 of the 13 children who underwent surgery were seizure-free, one had greater than 75% reduction in seizures, two were unchanged, and one was lost to follow-up. New seizures developed in one child from a contralateral tuber. CONCLUSIONS: Surgical resection of an ET/R alleviates seizures in most children with TSC and intractable epilepsy. The scalp EEG and MRI help define the ET/R and improve case selection when ictal SPECT is nonlocalizing.

Adolescent↗
PubMed1978

Tuberous sclerosis. Comparison of computed tomography and conventional neuroradiology.

Sixty-two patients with tuberous sclerosis were studied by skull radiography. In addition, 16 had CT scanning, 26 had air studies, and 5 had cerebral angiography. Both subependymal and parenchymal tubers were shown on CT; all had a higher density than the brain and none were enhanced by contrast material. CT showed tubers in 13 of 16 patients, including 4 of 6 patients with glioma and hydrocephalus. Air studies showed subependymal tubers in 12 of 26 patients. Four other patients had intraventricular gliomas but no tubers. Skull radiographs showed spotty calcification, compatible with tuberous sclerosis, in 30 cases. Four patients had calcification compatible with tumor. Angiograms were nonspecific, showing intraventricular masses but no tubers.

Air↗
PubMed2004

Managing epilepsy in tuberous sclerosis complex.

Epilepsy is very common in tuberous sclerosis complex and occurs in 80 to 90% of affected individuals during their lifetime. Onset usually occurs during childhood, and up to one third of children with tuberous sclerosis complex will develop infantile spasms. Although not completely understood, the incidence of epilepsy is thought to relate to the neuropathologic features of the disorder, including cortical tubers and other dysgenetic features. Individuals with tuberous sclerosis complex frequently have epileptiform features to their electroencephalograms. Treatment of epilepsy in tuberous sclerosis complex is similar to epilepsy resulting from other causes and includes anticonvulsant medications, the vagus nerve stimulator, and the ketogenic diet. Vigabatrin has been shown to be particularly effective in treating infantile spasms in the setting of tuberous sclerosis complex. Epilepsy surgery has a very important role in the management of children and adults with pharmacoresistant epilepsy in tuberous sclerosis complex.

Anticonvulsants↗
PubMed2005

Proton spectroscopic findings in children with epilepsy owing to tuberous sclerosis complex.

Tuberous sclerosis complex is an autosomal dominant disorder that often causes refractory seizures. The presence of multiple lesions makes it difficult to identify a single lesion responsible for the epilepsy. Our purpose is to assess the single-voxel proton spectroscopic findings of the tubers in 11 children with tuberous sclerosis complex. Prior to age 4 years, all of the patients had presented with epileptic seizures and multiple bilateral tubers in magnetic resonance images. Single-voxel proton spectroscopy was performed from the tubers especially showing epileptogenic activity using both the long and short echo time and in 14 controls. The results were analyzed using the Mann-Whitney U-test. Compared with the control group, the spectroscopic findings of tubers were characterized by decreased N-acetylaspartate to creatine ratios (1.43 +/- 0.33; P < .001) in both the long and short echo time spectra, increased choline to creatine ratios (0.91 +/- 0.082; P < .05), and myo-inositol to creatine ratios (0.97 +/- 0.19; P < .01) in the short echo time spectra. A lactate peak was detected in the regions corresponding to an epileptic focus on electroencephalography in six patients. Single-voxel proton spectroscopy could be a useful noninvasive method to evaluate epileptogenic tubers.

Adolescent↗
PubMed1999

MR imaging of tuberous sclerosis in neonates and young infants.

BACKGROUND AND PURPOSE: The MR imaging appearance of intracranial manifestations in tuberous sclerosis varies with age. The aim of this study was to specify MR characteristics in a coherent group of neonates and infants in order to distinguish them from the mature pattern. METHODS: The MR studies of seven patients under 3 months old were reviewed retrospectively. Imaging appearance, number, and distribution of tubers, white matter anomalies, subependymal nodules, and subependymal giant cell astrocytomas were analyzed. RESULTS: All patients had more white matter anomalies, subependymal nodules, subependymal giant cell astrocytomas, transmantle dysplasias, and left-hemispheric and temporal lesions, but less cortical tubers than did older patients in previous series. The lesions were easy to detect as hyperintense foci on T1-weighted images. Visibility as hypointensities on T2-weighted images was comparatively poor. CONCLUSION: The nodular subependymal and linear parenchymal tuberous sclerosis lesions in infants under 3 months old are hyperintense on T1-weighted images and hypointense on T2-weighted images as opposed to the reverse pattern of signal intensity in older persons. The scarce myelination helps to identify white matter anomalies, which become less visible as myelination progresses. Conversely, purely intracortical tubers are more difficult to diagnose in infants. Because the overall number and conspicuity of all other lesions in our series were greater than in previous series with older subjects, our findings indicate that infant age does not compromise, but facilitates, the correct MR diagnosis of tuberous sclerosis. Therefore, if tuberous sclerosis is clinically suspected within the first 3 months of life, imaging should not be delayed.

Brain↗
PubMed1996

Chronic renal failure and its treatment in tuberous sclerosis.

BACKGROUND: Chronic renal failure is rare in tuberous sclerosis, but its precise frequency is not known and treatment modalities have not been evaluated. METHODS: A questionnaire was addressed to the 260 French dialysis centres and the characteristics of 65 patients with tuberous sclerosis and chronic renal failure were analysed. RESULTS: In France the approximate prevalence of tuberous sclerosis with end-stage renal failure is 0.7 cases per million and that of end-stage renal failure in tuberous sclerosis 1 per 100. Tuberous sclerosis with chronic renal failure was more frequent in females (63.1%) and was diagnosed at a mean age of 29 years. Renal impairment was the first manifestation of tuberous sclerosis in about half the cases. Renal tumours were frequent, with angiomyolipomas in 15 cases (23.1%), cysts in 12 cases (18.5%), and both in 35 cases (53.8%). Malignancies were associated in nine cases (13.8%). Nephrectomy was done before dialysis in 21 cases (32.3%), and after the start of dialysis in six cases (9.2%). All but one of the 48 patients with end-stage renal failure were treated by dialysis; 20 were transplanted, with good results. CONCLUSIONS: Tuberous sclerosis with end-stage renal failure is rare. These patients require dialysis and renal transplantation, but we recommend binephrectomy after starting dialysis and before transplantation, given the risk of cancer and bleeding related to angiomyolipomas.

Adult↗
PubMed2004

Molecular genetic basis of tuberous sclerosis complex: from bench to bedside.

Tuberous sclerosis complex is an autosomal dominant disease of benign tumors occurring in multiple organ systems of the body. Either of two genes, TSC1 or TSC2, can be mutated, resulting in the tuberous sclerosis complex phenotype. The protein products of the tuberous sclerosis complex genes, hamartin (TSC1) and tuberin (TSC2), have been discovered to play important roles in several cell-signaling pathways. Knowledge regarding the function of the tuberin-hamartin complex has led to therapeutic intervention trials. Numerous pathogenic mutations have been elucidated in individuals affected with tuberous sclerosis complex. Information on the type and distribution of nearly 1000 mutations in the two genes is discussed. Mosaicism for tuberous sclerosis complex mutations has been documented, complicating provision of genetic counseling to families. Emerging genotype-phenotype correlations should provide guidance for better medical care of individuals with tuberous sclerosis complex.

Animals↗
PubMed1994

Field evaluation of transgenic potato plants expressing an antisense granule-bound starch synthase gene: increase of the antisense effect during tuber growth.

Transgenic plants of a tetraploid potato cultivar were obtained in which the amylose content of tuber starch was reduced via antisense RNA-mediated inhibition of the expression of the gene encoding granule-bound starch synthase (GBSS). GBSS is one of the key enzymes in the biosynthesis of starch and catalyses the formation of amylose. The antisense GBSS genes, based on the full-length GBSS cDNA driven by the 35S CaMV promoter or the potato GBSS promoter, were introduced into the potato genome by Agrobacterium tumefaciens-mediated transformation. Expression of each of these genes resulted in the complete inhibition of GBSS gene expression, and thus in the production of amylose-free tuber starch, in mature field-grown plants originating from rooted in vitro plantlets of 4 out of 66 transgenic clones. Clones in which the GBSS gene expression was incompletely inhibited showed an increase of the extent of inhibition during tuber growth. This is likely to be due to the increase of starch granule size during tuber growth and the specific distribution pattern of starch components in granules of clones with reduced GBSS activity. Expression of the antisense GBSS gene from the GBSS promoter resulted in a higher stability of inhibition in tubers of field-grown plants as compared to expression from the 35S CaMV promoter. Field analysis of the transgenic clones indicated that inhibition of GBSS gene expression could be achieved without significantly affecting the starch and sugar content of transgenic tubers, the expression level of other genes involved in starch and tuber metabolism and agronomic characteristics such as yield and dry matter content.

Amylose↗
PubMed1992

Differential distribution of ampullary and tuberous processing in the torus semicircularis of Eigenmannia.

Gymnotiform electric fish sense low- and high-frequency electric signals with ampullary and tuberous electroreceptors, respectively. We employed intracellular recording and labeling methods to investigate ampullary and tuberous information processing in laminae 1-5 of the dorsal torus semicircularis of Eigenmannia. Ampullary afferents arborized extensively in laminae 1-3 and, in some cases, lamina 7. Unlike tuberous afferents to the torus, ampullary afferents had numerous varicosities along their finest-diameter branches. Neurons that were primarily ampullary were found in lamina 3. Neurons primarily excited by tuberous stimuli were found in lamina 5 and, more rarely, in lamina 4. Cells that had dendrites in lamina 1-3 and 5 could be recruited by both ampullary and tuberous stimuli. These bimodal cells were found in lamina 4. During courtship, Eigenmannia produces interruptions of its electric organ discharges. These interruptions stimulate ampullary and tuberous receptors. The integration of ampullary and tuberous information may be important in the processing of these communication signals.

Animals↗