Diagnostic testing for Rett syndrome by DHPLC and direct sequencing analysis of the MECP2 gene: identification of several novel mutations and polymorphisms.

Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder affecting 1/10,000-15,000 girls. The disease-causing gene was identified as MECP2 on chromosome Xq28, and mutations have been found in approximately 80% of patients diagnosed with RTT. Numerous mutations have been identified in de novo and rare familial cases, and they occur primarily in the methyl-CpG-binding and transcriptional-repression domains of MeCP2.

Spinal nerve injury enhances subthreshold membrane potential oscillations in DRG neurons: relation to neuropathic pain.

Primary sensory neurons with myelinated axons were examined in vitro in excised whole lumbar dorsal root ganglia (DRGs) taken from adult rats up to 9 days after tight ligation and transection of the L(5) spinal nerve (Chung model of neuropathic pain). Properties of subthreshold membrane potential oscillations, and of repetitive spike discharge, were examined. About 5% of the DRG neurons sampled in control DRGs exhibited high-frequency, subthreshold sinusoidal oscillations in their membrane potential at rest (V(r)), and an additional 4.

Influence of mutation type and X chromosome inactivation on Rett syndrome phenotypes.

We screened 71 sporadic and 7 familial Rett syndrome (RTT) patients for MECP2 mutations by direct sequencing and determined the pattern of X chromosome inactivation (XCI) in 39 RTT patients. We identified 23 different disease-causing MECP2 mutations in 54 of 71 (76%) sporadic patients and in 2 of 7 (29%) familial cases. We compared electrophysiological findings, cerebrospinal fluid neurochemistry, and 13 clinical characteristics between patients carrying missense mutations and those carrying truncating mutations.

Tactile allodynia in the absence of C-fiber activation: altered firing properties of DRG neurons following spinal nerve injury.

We examined the relation between ectopic afferent firing and tactile allodynia in the Chung model of neuropathic pain. Transection of the L5 spinal nerve in rats triggered a sharp, four- to six-fold increase in the spontaneous ectopic discharge recorded in vivo in sensory axons in the ipsilateral L5 dorsal root (DR). The increase, which was not yet apparent 16 h postoperatively, was complete by 24 h.

Terminal osseous dysplasia with pigmentary defects maps to human chromosome Xq27.3-xqter.

We have identified a four-generation family with 10 affected females manifesting one or more of the following features: osseous dysplasia involving the metacarpals, metatarsals, and phalanges leading to brachydactyly, camptodactyly, and other digital deformities; pigmentary defects on the face and scalp; and multiple frenula. There were no affected males. We performed X-inactivation studies on seven affected females, using a methylation assay at the androgen receptor locus; all seven demonstrated preferential inactivation of their maternal chromosomes carrying the mutation, and two unaffected females showed a random pattern.

Functional cross-excitation between afferent A- and C-neurons in dorsal root ganglia.

Electrophysiological recordings were made in vitro from primary afferent neurons with unmyelinated axons (C-neurons) in excised rat dorsal root ganglia. Spike activity triggered in neurons with myelinated axons (A-neurons) by stimulation of the peripheral nerve or the dorsal root produced a transient depolarization in passive neighboring C-neurons that share the same ganglion. About 90% of neurons sampled responded with this "cross-depolarization".

Candidate gene analysis in Rett syndrome and the identification of 21 SNPs in Xq.

Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder that affects females. Exclusion mapping studies using a new family with maternal inheritance of RTT defined Xq28 as the candidate region for the RTT gene. Six candidate genes were selected for mutation analysis based on their established expression patterns and known functions in the CNS.

Rett syndrome and beyond: recurrent spontaneous and familial MECP2 mutations at CpG hotspots.

Rett syndrome (RTT) is a neurodevelopmental disorder characterized by loss of acquired skills after a period of normal development in infant girls. The responsible gene, encoding methyl-CpG binding protein 2 (MeCP2), was recently discovered. Here we explore the spectrum of phenotypes resulting from MECP2 mutations.

Chronic rhinitis: a manifestation of chronic lymphocytic leukemia.

Chronic rhinitis is a condition that occasionally reflects underlying systemic disease. In such cases, physical examination, nasal endoscopy, and computed tomography may be nonspecific. Diagnosis and treatment of the underlying illness may improve nasal symptoms, which may prove refractory to standard rhinitis therapy.

Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2.

Rett syndrome (RTT, MIM 312750) is a progressive neurodevelopmental disorder and one of the most common causes of mental retardation in females, with an incidence of 1 in 10,000-15,000 (ref. 2). Patients with classic RTT appear to develop normally until 6-18 months of age, then gradually lose speech and purposeful hand use, and develop microcephaly, seizures, autism, ataxia, intermittent hyperventilation and stereotypic hand movements.

Membrane potential oscillations in dorsal root ganglion neurons: role in normal electrogenesis and neuropathic pain.

Abnormal afferent discharge originating at ectopic sites in injured primary sensory neurons is thought to be an important generator of paraesthesias, dysaesthesias, and chronic neuropathic pain. We report here that the ability of these neurons to sustain repetitive discharge depends on intrinsic resonant properties of the cell membrane and that the prevalence of this characteristic increases after nerve injury. Recording from primary sensory neurons in excised rat dorsal root ganglia, we found that some cells show subthreshold oscillations in their membrane potential.

Effect of age and nerve injury on cross-excitation among sensory neurons in rat dorsal root ganglia.

Spike activity in dorsal root ganglion (DRG) neurons depolarizes passive neighbors that share the same ganglion. We asked whether age or prior nerve injury affect this 'cross-depolarization' signal. Intracellular recordings made from excised DRGs in vitro revealed that the prevalence and duration of cross-depolarization were no greater in adult than in young rats, and that its amplitude was significantly smaller in adults.

Cross-excitation in dorsal root ganglia does not depend on close cell-to-cell apposition.

About 90% of neurons in dorsal root ganglia (DRGs) of rats 2-5 weeks of age are depolarized and excited by impulse activity in neighboring neurons that share the same DRG. Synaptic contacts are extremely rare in DRGs, but instances of close membrane apposition between pairs of neuronal somata are not uncommon, especially in prenatal rats. Close membrane apposition could permit electrotonic interactions among neighboring DRG neurons.

Spike-evoked suppression and burst patterning in dorsal root ganglion neurons of the rat.

1. A low level of spontaneous impulse discharge is generated within dorsal root ganglia (DRGs) in intact animals, and this activity is enhanced following nerve injury. Many physiological stimuli present in vivo are capable of augmenting this ectopic discharge.

Cloning and expression of an Arabidopsis thaliana cDNA encoding a monofunctional aspartate kinase homologous to the lysine-sensitive enzyme of Escherichia coli.

As in many bacterial species, the first enzymatic reaction of the aspartate-family pathway in plants is mediated by several isozymes of aspartate kinase (AK) that are subject to feedback inhibition by the end-product amino acids lysine or threonine. So far, only cDNAs and genes encoding threonine-sensitive AKs have been cloned from plants. These were all shown to encode polypeptides containing two linked activities, namely AK and homoserine dehydrogenase (HSD), similar to the Escherichia coli thrA gene encoding a threonine-sensitive bifunctional AK/HSD isozyme.

Chemically mediated cross-excitation in rat dorsal root ganglia.

Primary afferent neurons in mammalian dorsal root ganglia (DRGs) are anatomically isolated from one another and are not synaptically interconnected. As such, they are classically thought to function as independent sensory communication elements. However, it has recently been shown that most DRG neurons are transiently depolarized when axons of neighboring neurons of the same ganglion are stimulated repetitively.

Three-dimensional modelling of tumor-induced ovarian angiogenesis.

It is now well established that unrestricted growth of tumors is dependent upon angiogenesis. However, previous studies on tumor growth have not yet revealed how the transition to an angiogenetic state in ovarian malignancy is reflected in the vascular architecture of the ovary. We report here our preliminary observations based upon three-dimensional imaging of normal and tumor-induced ovarian angiogenesis created with a computer-assisted three-dimensional interactive application.

Isolation and biological properties of scorpionvenom proteins: iv-comparative study on four proteinases isolated from the venom of isometrus vittatus.

1) Four proteinases were isolated from the venom of a local scorpion species Isonietrus vittatus collected from Sindh region, Pakistan and named PRO,(IA) PRO,(IB) PRO(IVA) and PRO(IVB). 2) Successive chromatography on Sephadex G-50, CM-Cellulose and Sephadex G-100 yield 25.5 mg, 20.

Ongoing activity in neuroma afferents bearing retrograde sprouts.

Electrophysiological recordings were made from axons teased from the sciatic nerve 17-34 mm (mean 26.8 mm) central to a chronic nerve-end neuroma in adult rats. 23 fibers (2% of those sampled) appeared to have had a sprout(s) that grew in the retrograde (central) direction for at least this distance.

Axonal cross-excitation in nerve-end neuromas: comparison of A- and C-fibers.

1. We recorded from single afferent axons ending in chronic sciatic nerve end neuromas in rats with the use of the teased-fiber method. Axons were sought that had ongoing impulse discharge originating in the neuroma.

Giant salivary calculi: an orocervical fistula caused by a submandibular gland calculus.

Large calculi of the salivary glands are rare. They may go undetected for many years. The authors report three cases of giant submandibular gland calculi.

Ventilation-perfusion patterns in lung diseases (with reference to those observed in pulmonary embolism).

The frequency distributions of ventilation-perfusion (V-P) patterns in various lung diseases were compared to those observed in pulmonary embolism in order to determine whether the specific V-P patterns for pulmonary embolism constituted a frequent finding in these disorders. The results showed that a segmental or lobar perfusion defect with normal ventilation, was associated with a high probability of thromboembolic lung disease, and was not present in any of the other lung diseases studied.

Amplitude distribution in the right ventricle.

Amplitude distribution in the right ventricle obtained from ECG-gated ventriculography has been reviewed and six amplitude distribution patterns were identified. Homogeneous distribution was rarely observed even in patients without any cardiac or pulmonary diseases. Furthermore, there was no difference in frequency distribution of the amplitude distribution patterns between the control group, patients with coronary diseases, and those with recent inferior myocardial infarction.

Unusual cholescintigraphic findings in polyarteritis nodosa.

Bile duct cysts as a consequence of liver infarcts have exceptionally been described in polyarteritis nodosa. A case is reported in which necrotic changes due to arterial occlusion, as well as the resulting hepatic bile duct cysts, were clearly demonstrated by diethyl IDA cholescintigraphy.