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Supratentorial tuber location and autism in tuberous sclerosis complex.

The high rate of autism in tuberous sclerosis complex provides an opportunity to study the pathogenesis of autism. This study investigated the relationship between a DSM-IV diagnosis of autism and tuber location in a sample of 50 individuals with tuberous sclerosis complex. Chi-square analyses revealed no differences between individuals with autism (n = 15) and those without autism (n = 35) on the occurrence of tubers in the right or left frontal, occipital, parietal, or temporal regions. There were no differences between the two groups in the occurrence of tubers in subcortical or cortical regions. In the largest sample to date, these results fail to support the hypothesis that supratentorial tuber location is a marker for autism.

Autistic Disorder↗

Tuberous Sclerosis Consensus Conference: recommendations for diagnostic evaluation. National Tuberous Sclerosis Association.

At the recent Tuberous Sclerosis Consensus Conference, a subcommittee proposed recommendations to guide the rational use of diagnostic studies in patients with tuberous sclerosis complex. Recommendations were made for diagnostic evaluation at the time of diagnosis, when testing helps both to establish the diagnosis and to identify potential complications. Additional guidelines were proposed for the ongoing surveillance of established patients to detect later complications of tuberous sclerosis complex. In the absence of comprehensive population studies to govern the use of diagnostic studies in individuals with tuberous sclerosis complex, the panel developed guidelines based on the disorder's natural history, concentrating on complications that are common, clinically significant, and more easily managed when found early. Finally, the group made suggestions for the use of diagnostic tests to identify family members who have tuberous sclerosis complex. Although these recommendations should standardize and improve our use of diagnostic studies in individuals with tuberous sclerosis complex, the clinical approach in a given patient must remain flexible enough to meet the needs of individual patients and families.

Adult↗

Anomalous inhibitory circuits in cortical tubers of human tuberous sclerosis complex associated with refractory epilepsy: aberrant expression of parvalbumin and calbindin-D28k in dysplastic cortex.

Damage or loss of inhibitory cortical gamma-aminobutyric acid (GABA)ergic interneurons is associated with impaired inhibitory control of neocortical pyramidal cells, leading to hyperexcitability and epileptogenesis. The calcium binding proteins parvalbumin and calbindin-D(28k) are expressed in subpopulations of GABAergic local circuit neurons in the neocortex and can serve as neuronotypic markers. Parvalbumin and calbindin-D(28k) facilitate the neuron's ability to sustain firing and provide neuroprotection. The goal of this study was to assess the hitherto unknown status of inhibitory interneurons in cortical tubers of human tuberous sclerosis complex. Surgically excised cortical tubers from three patients with tuberous sclerosis complex were evaluated immunohistochemically with antibodies to parvalbumin and calbindin-D(28k). Cortical specimens from young patients with intractable seizures, including microdysgenesis (n = 3), postischemic cortical scarring (n = 1), porencephaly (n = 1), postictal gliosis (n = 3), and low-grade neuronal or glial tumors (n = 5), were also examined for comparison. In cortical tubers, calcium binding protein immunoreactivities (calbindin-D(28k) > parvalbumin) were present in medium- or large-size dysplastic neurons, whereas giant or ballooned cells were parvalbumin or calbindin-D(28k) negative. In microdysgenesis, a nearly normal number of parvalbumin-positive neurons and a decreased number of calbindin-D(28k)-positive neurons were present. In peritumoral but more so in gliotic cortex, a coordinate decrease of parvalbumin and calbindin-D(28k) immunoreactivities was present. Our findings indicate that the expression of parvalbumin or calbindin-D(28k) by subpopulations of dysplastic neurons in cortical tubers is aberrant and denotes dysfunctional inhibitory circuits inept for excitoprotection.

Adolescent↗

Metabolic engineering of potato tuber carotenoids through tuber-specific silencing of lycopene epsilon cyclase.

BACKGROUND: Potato is a major staple food, and modification of its provitamin content is a possible means for alleviating nutritional deficiencies. beta-carotene is the main dietary precursor of vitamin A. Potato tubers contain low levels of carotenoids, composed mainly of the xanthophylls lutein, antheraxanthin, violaxanthin, and of xanthophyll esters. None of these carotenoids have provitamin A activity. RESULTS: We silenced the first dedicated step in the beta-epsilon- branch of carotenoid biosynthesis, lycopene epsilon cyclase (LCY-e), by introducing, via Agrobacterium-mediated transformation, an antisense fragment of this gene under the control of the patatin promoter. Real Time measurements confirmed the tuber-specific silencing of Lcy-e. Antisense tubers showed significant increases in beta-beta-carotenoid levels, with beta-carotene showing the maximum increase (up to 14-fold). Total carotenoids increased up to 2.5-fold. These changes were not accompanied by a decrease in lutein, suggesting that LCY-e is not rate-limiting for lutein accumulation. Tuber-specific changes in expression of several genes in the pathway were observed. CONCLUSION: The data suggest that epsilon-cyclization of lycopene is a key regulatory step in potato tuber carotenogenesis. Upon tuber-specific silencing of the corresponding gene, beta-beta-carotenoid and total carotenoid levels are increased, and expression of several other genes in the pathway is modified.

Carotenoids↗

Review on tropical root and tuber crops. II. Physiological disorders in freshly stored roots and tubers.

Tropical root and tubers, including cassava, sweet potato, yams and aroids, have been reported to show an increase in respiratory activity after harvest and injury and subsequent storage in association with their deterioration. This leads to loss of water and carbohydrate. Cassava roots often show discoloration of the tissue with development of pigments in the xylem vessels (vascular streaking or primary/physiological deterioration). This has been established to be enzymatic in nature. Pruning the cassava stem, leaving about a 20- to 30-cm stub prior to harvest, could delay the onset of primary deterioration. Sweet potato roots and yam tubers show a peak respiratory activity immediately or 1 d after harvest. The respiratory rate, however, declines during the subsequent storage period. Yam tubers show a further increase in respiratory activity at the breakage of dormancy occurring at the time of sprouting. Dormancy in yam tubers has been studied in some detail. Different species of yams vary in their dormancy period, a major factor that accounts for the variation in their storage life. Little information is available on the dormancy of sweet potato and aroids. Tropical roots and tubers exhibit "chilling injury" when stored at temperatures below a critical level. The critical cold-storage temperatures range between 10 and 15 degrees C for different tropical root and tuber crops.

Carbohydrates↗

Ezrin and moesin expression within the developing human cerebrum and tuberous sclerosis-associated cortical tubers.

The ERM (ezrin, radixin, and moesin) proteins belong to the band-4.1 superfamily of membrane-cytoskeleton-linking proteins which bind to the actin cytoskeleton via their C-terminal sequences and bind ERM binding membrane proteins (ERMBMPs). We investigated the immunohistochemical expression of two of the ERM proteins (ezrin and moesin) in developing human cerebral cortex and in cortical tubers from patients with tuberous sclerosis (TSC), to assess possible consequences of TSC gene product malfunction or inactivation in the developing brain in relation to ERM protein expression. Ezrin is abundantly expressed within radial glia and migrating cells in the intermediate zone in the prenatal human cerebrum, while moesin is primarily expressed in vascular endothelial cells in developing and adult human brain and scattered microglia in adult brain. In addition, both ezrin and moesin are abundantly co-expressed with hamartin and tuberin within a population of abnormal cells in TSC-associated cortical tubers. The expression of these two proteins--primarily ezrin--suggests that they are developmentally regulated and abundantly expressed in germinal matrix and/or migrating cells during cerebral cortical development. In TSC-associated cortical tubers, both proteins appeared to be up-regulated and are co-localized within a population of abnormal neuroglial cells typical of those seen in tubers. Expression of these proteins and their co-localization with tuberin and hamartin in these cells may suggest a compensatory up-regulation in response to TSC gene mutation.

Cytoskeletal Proteins↗

Absence of allelic loss in cytomegalic neurons of cortical tuber in the Eker rat model of tuberous sclerosis.

The Eker rat is an animal model of tuberous sclerosis caused by a mutation in the Tsc2 gene encoding a tumor suppressor protein, tuberin. According to Knudson's two-hit theory, renal carcinomas and other tumors develop in various organs. Although the incidence of brain lesions is lower in the Eker rat than in human tuberous sclerosis, a cortical tuber was recently found in the cerebrum of an Eker carrier. In this study, we examined whether neuronal cytomegaly in the Eker rat tuber is caused by deletion of the normal Tsc2 allele and resultant loss of tuberin, as is the case with the majority of renal carcinomas. A combination of laser capture microdissection and semi-nested polymerase chain reaction demonstrated the presence of the wild-type Tsc2 allele in the cytomegalic neurons isolated individually. Immunohistochemistry also detected positive tuberin immunoreactivity in many of these giant neurons. These findings were in sharp contrast to those of renal carcinoma cells deriving from allelic loss. Our results provide evidence that many if not all cytomegalic neurons of a cortical tuber occur in the absence of allelic loss.

Animals↗

Ultrastructure of tuberous sclerosis: cortical tuber and subependymal tumor.

Ultrastructural examination of two biopsy cases of tuberous sclerosis, a subependymal tumor and a cortical tuber, revealed giant cells with astrocytic features in both cases. These included multipolar processes containing glial filaments, glycogen, and membrane-bound dense bodies, as well as formation of hemidesmosomes with pia and vascular basement membranes. Megamitochondria were also seen within glial processes. In addition to the numerous glial-glial contacts encountered in both cases, rare neuroglial junctions suggesting aberrant synapse formation were observed within the cortical tuber. This observation, in concert with the organization of multiple small neurites along large, aberrant astrocyte processes found within the tuber, mimics features of neuroembryonic development described in lower mammals and nonhuman primates. Such a parallel in ultrastructural morphology supports a primarily dysplastic nature for the lesions in tuberous sclerosis.

Adult↗

Frequency of tuberous sclerosis in San-in district (Japan) and birth weight of patients with tuberous sclerosis.

Fifty-two patients with tuberous sclerosis including 44 propositi were collected from 11 hospitals and 20 institutions in the San-in district. Of the 52 patients 44 were alive at the time of the study and the prevalence of tuberous sclerosis among the general population of the San-in district in October 1979 was estimated to be one in 31,000 (3.2 x 10(-5)), which was the highest value among the surveys in certain geographical areas. The frequency of tuberous sclerosis in live-births was estimated to be one in 24,000 (4.0 x 10(-5)). The frequency of the sporadic cases in live-births was one in 31,000 (3.2 X 10(-5) and the mutation rate was directly estimated to be 1.6 X 10(-5) per gene per generation. A difference between the parental age or birth order of the sporadic cases and those of controls was not detected. The mean birth weight for the tuberous sclerosis group was 2,834 g which was slightly less than the 2,985 g for their normal sibs. The frequency of low birth weight, less than 2,500 g, among the children with tuberous sclerosis was 30% (7/23), which was 4 times that in the general population (P less than 0.005). These facts suggest that the intrauterine growth is affected in a considerable number of the patients.

Adolescent↗

Identification of the epileptogenic tuber in patients with tuberous sclerosis: a comparison of high-resolution EEG and MEG.

PURPOSE: We compared epileptiform activity recorded with EEG and magnetoencephalography (MEG) in 19 patients with tuberous sclerosis complex (TSC) and epilepsy. METHODS: High-resolution (HR) EEG, HR-MEG, and 1.5-T MRI scans were performed. Epileptiform spikes were identified in EEG and MEG recordings offline by three observers. Spikes for which the interobserver agreement (spike consensus) was >0.40 were used for source localization with CURRYV 3.0 software. MUSIC analysis was performed. The distance between the source determined from EEG and MEG recordings and the border of the closest tuber was calculated and compared. RESULTS: Consensus spikes (kappa >0.4) were identified in 12 patients in the EEG recording and in 14 patients in the MEG recording. MEG sources were closer to tubers in all but one patient. Three patients underwent epilepsy surgery, two of whom are seizure free after complete resection of the tuber. CONCLUSIONS: In patients with TSC, epileptogenic sources identified on MEG are closer to the presumed epileptogenic tuber than are similar sources identified on EEG. Moreover, spike consensus is greater with MEG. Clear identification of the epileptogenic zone may offer opportunities for surgery in patients with TSC with intractable epilepsy.

Adolescent↗

Ocatin. A novel tuber storage protein from the andean tuber crop oca with antibacterial and antifungal activities.

The most abundant soluble tuber protein from the Andean crop oca (Oxalis tuberosa Mol.), named ocatin, has been purified and characterized. Ocatin accounts for 40% to 60% of the total soluble oca tuber proteins, has an apparent molecular mass of 18 kD and an isoelectric point of 4.8. This protein appears to be found only in tubers and is accumulated only within the cells of the pith and peridermis layers (peel) of the tuber as it develops. Ocatin inhibits the growth of several phytopathogenic bacteria (Agrobacterium tumefaciens, Agrobacterium radiobacter, Serratia marcescens, and Pseudomonas aureofaciens) and fungi (Phytophthora cinnamomi, Fusarium oxysporum, Rhizoctonia solani, and Nectria hematococcus). Ocatin displays substantial amino acid sequence similarity with a widely distributed group of intracellular pathogenesis-related proteins with a hitherto unknown biological function. Our results showed that ocatin serves as a storage protein, has antimicrobial properties, and belongs to the Betv 1/PR-10/MLP protein family. Our findings suggest that an ancient scaffolding protein was recruited in the oca tuber to serve a storage function and that proteins from the Betv 1/PR-10/MLP family might play a role in natural resistance to pathogens.

Amino Acid Sequence↗

Novel cerebral lesions in the Eker rat model of tuberous sclerosis: cortical tuber and anaplastic ganglioglioma.

The Eker rat is a model for human tuberous sclerosis (TSC) caused by a mutation in the Tsc2 gene. We describe here histological and immunohistochemical findings of the brain lesions in Eker rats, with emphasis on 2 novel lesions found in this study: a cortical tuber and an anaplastic ganglioglioma. The rat cortical tuber resembled those of humans, and further confirmed the value of this animal model as a tool for investigating the molecular pathology of tuberous sclerosis. On the other hand, the rat anaplastic ganglioglioma had features of a malignant neoplasm that are absent from human subependymal giant cell astrocytomas.

Animals↗

Secondary parathyroid hyperplasia in tuberous sclerosis: report of a case with large eosinophilic ganglion-like cells similar to those of subependymal giant cell astrocytoma, tubers, and atypical angiomyolipoma.

We report a case of secondary parathyroid hyperplasia in a 49-year-old man with tuberous sclerosis. Two parathyroid glands had collections of large, eosinophilic ganglion-like endocrine cells that to our knowledge have not been previously described at this site. These cells are morphologically similar to those of subependymal giant cell astrocytoma, tubers, and atypical angiomyolipoma, all of which may arise in the setting of tuberous sclerosis. These large, eosinophilic ganglion-like cells found in different affected organs appear to be distinctive of tuberous sclerosis. We suggest these large eosinophilic cells arise from a common stem cell precursor that acquires variable phenotypes according to alterations in the cellular microenvironment.

Angiomyolipoma↗

Tuberous sclerosis and multiple tubers: localizing the epileptogenic zone.

Tuberous sclerosis complex (TSC) is associated with medically refractory seizures and developmental delay in children. These epilepsies are often resistant to antiepileptic drugs (AEDs), may be quite severe, and usually have a negative impact on the child's neurological and cognitive development. It is believed that functional outcome is improved if seizures can be controlled at an early age. The surgical treatment of intractable epilepsy in children and adults with TSC has gained significant interest in recent years. Previously published studies have shown a potential benefit from resection of single tubers, with most of the results noted in relatively older children. All of these reports support the idea that if a single primary epileptogenic tuber/region can be identified, then a surgical approach is appropriate. However, most children with TSC have multiple potentially epileptogenic tubers, rendering localization challenging, and they are therefore rejected as possible surgical candidates. We have utilized a novel surgical approach using invasive intracranial monitoring, which is typically multistaged and bilateral. Here we present an illustrative case of a young boy with TSC and medically refractory epilepsy who underwent a staged surgical approach. This multistage surgical approach has been useful in identifying both primary and secondary epileptogenic zones in TSC patients with multiple tubers. Multiple or bilateral seizure foci are not necessarily a contraindication to surgery in selected TSC patients. Long-term follow-up will determine whether this approach has durable effects. We await better methods for identifying the epileptogenic zone, both noninvasive and invasive.

Brain↗

Linkage investigation of three putative tuberous sclerosis determining loci on chromosomes 9q, 11q, and 12q. The Tuberous Sclerosis Collaborative Group.

Previous linkage studies in tuberous sclerosis have implicated three disease determining loci at 9q, 11q, and 12q. We have collated phenotypic and genotypic data on 1622 members of 128 families with tuberous sclerosis in order to evaluate simultaneously the evidence for these putative loci. Affection status in the family members has been reassessed using uniform diagnostic criteria and genotypic data extensively checked before analysis under alternative models of locus heterogeneity. One tuberous sclerosis determining locus, accounting for approximately 50% of the families studied, has been found to map in the region of D9S10 on 9q34 but no evidence has been found to support the existence of major loci on 11q or 12q. A locus, or loci, elsewhere in the genome is likely to account for tuberous sclerosis in most non-chromosome 9 linked families.

Chromosome Mapping↗

[Cystic brain tumor associated with tuberous sclerosis -familial occurrence of tuberous sclerosis with normal intelligence- (author's transl)].

Brain tumors associated with tuberous sclerosis are often found in the wall of the ventricles near the foramen of Monro and present with symptoms of increased intracranial pressure due to occlusion of the CSF pathway. The authors reported a case of such a brain tumor which presented predominantly focal neurological signs because of a large cyst function. This 8-year-and-4-month old girl experienced her first seizure attack at the age of 1-year-and-3-month. Six moths before admission, she complained of headache which lasted for several days. CT scans at that time revealed mass lesions in both lateral ventricles which were mildly dilated. A round low density area, considered to be a cyst, was found lateral to the calcified tumor of the left lateral ventricle extending into the adjacent parenchyma. Two months later, she noticed weakness in her right extremities, difficulty in buttoning and tendency to stumbling, and these were slowly progressive. Her past history was non-contributory. CT examinations of her mother and elder brother with adenoma sebaceum indicated that both had multiple calcifications in the ventricular walls and they were clinically diagnosed as having an incomplete form of tuberous sclerosis. On admission to the Department of Neurosurgery, Shinshu University Hospital on March 23, 1979, the patient was noted to have right hemiparesis and hyper-reflexia. She could barely walk but was unable to write with her right hand. Fundoscopic examination was normal. On general physical examinations, characteristic skin lesions including adenoma sebaceum, shagreen patch and depigmented patches were found. The second CT scans taken at the time of admission revealed that the low density area markedly enlarged, while the size of the tumors and ventricles remained essentially unchanged. A left parietal craniotomy was performed with a preoperative diagnosis of cystic tumor of the lateral ventricle associated with tuberous sclerosis. The tumor in the left lateral ventricle was found extending from the trigone to the anterior horn beyond the foramen of Monro. Histopathological diagnosis of typicaL benign giant-celled astrocytoma was made. The immediate postoperative course was uneventful except for a temporary worsening of the right motor weakness. V-P shunt was necessary because she developed signs and symptoms of increased intracranial pressure due to hydrocephalus two weeks after operation. At the time of dismissal from the hospital one month postoperatively, she was neurologically free except for the mild right hemiparesis. To the best of our knowledge, the present case is the first reported in the literature, in which a brain tumor associated with cyst formation verified in a patient of tuberous sclerosis.

Adult↗

Use of an in vitro tuberization system to study tuber protein gene expression.

Nodal cuttings from micropropagated potato plantlets give rise to microtubers when placed on Murashige and Skoog medium containing 6% sucrose and 2.5 mg/liter kinetin and incubated in the dark at 19 degrees C. Microtubers produced from the cultivar Superior were shown to contain the same characteristic group of proteins as field-grown tubers. As with field-grown tubers, the 40,000-dalton major tuber glycoprotein, patatin, accumulated to high levels in microtubers, reaching 3.7 +/- 0.2 mg/g fresh weight after 90 d. Also in agreement with field-grown plants, stems and leaves of micropropagated plantlets did not contain detectable levels of patatin, but small amounts of an electrophoretically distinct form accumulated transiently in roots. Patatin mRNA is readily detectable in developing microtubers 15 d after transfer of the cuttings to inductive medium. Patatin mRNA was also present in roots, but as with field-grown plants, was 50- to 100-fold less abundant and could be distinguished from that in tubers by primer extension. Microtuber development and patatin accumulation were inhibited by gibberellic acid.

Gene Expression Regulation↗

Overexpression of the sucrose transporter SoSUT1 in potato results in alterations in leaf carbon partitioning and in tuber metabolism but has little impact on tuber morphology.

The aim of this work was to examine the consequences of the heterologous expression of a spinach ( Spinacia oleracea L.) sucrose transporter ( SoSUT1) in potato ( Solanum tuberosum L.). Many studies have indicated that reduction of the expression of this class of sucrose transporter has deleterious effects on plant growth and development; however, until now the possibility of improving plant performance by enhancing the expression of this sucrose transporter has not been reported. With this intention we constructed a chimeric construct in which SoSUT1 was cloned in-frame with the myc epitope. We confirmed that this construct, SoSUT1m, was able to mediate sucrose transport by expression in the yeast strain SUSY7. SoSUT1m was expressed in wild-type potato in the sense orientation under the control of the cauliflower mosaic virus 35S promoter to evaluate the effect of an increased constitutive expression of a class-I sucrose transporter. We confirmed that these plants displayed expression of SoSUT1 at both the transcript and protein level and that microsomal fragments isolated from selected lines had an increased sucrose uptake capacity. Analysis of metabolism of these lines indicated that the leaves were characterised by a reduced sucrose level yet exhibited little change in photosynthetic rate. Furthermore, despite the observed increase in sugar (and reduction in amino acid) levels within the tubers, there was little change in either starch content or tuber yield in the transformants. In summary, the genetic manipulation described in this paper resulted in a shift in carbon partitioning in both leaves and tubers and an increased sucrose uptake rate in plasma-membrane vesicles isolated from these lines, but had little impact on tuber metabolism or morphology.

Carbohydrate Metabolism↗