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D D Wang

Publications and source records attributed to D D Wang.

13 recordsLinked to original sources
PubMed2003

GABA depolarizes neuronal progenitors of the postnatal subventricular zone via GABAA receptor activation.

Previous studies have reported the presence of migrating and dividing neuronal progenitors in the subventricular zone (SVZ) and rostral migratory stream (RMS) of the postnatal mammalian brain. Although the behaviour of these progenitors is thought to be influenced by local signals, the nature and mode of action of the local signals are largely unknown. One of the signalling molecules known to affect the behaviour of embryonic neurons is the neurotransmitter GABA. In order to determine whether GABA affects neuronal progenitors via the activation of specific receptors, we performed cell-attached, whole-cell and gramicidin perforated patch-clamp recordings of progenitors in postnatal mouse brain slices containing either the SVZ or the RMS. Recorded cells displayed a morphology typical of migrating neuronal progenitors had depolarized zero-current resting potentials, and lacked action potentials. A subset of progenitors contained GABA and stained positive for glutamic acid decarboxylase 67 (GAD-67) as shown by immunohistochemistry. In addition, every neuronal progenitor responded to GABA via picrotoxin-sensitive GABAA receptor (GABAAR) activation. GABAARs displayed an ATP-dependent rundown and a low sensitivity to Zn2+. GABA responses were sensitive to benzodiazepine agonists, an inverse agonist, as well as a barbiturate agonist. While GABA was hyperpolarizing at the zero-current resting potentials, it was depolarizing at the cell resting potentials estimated from the reversal potential of K+ currents through a cell-attached patch. Thus, our study demonstrates that neuronal progenitors of the SVZ/RMS contain GABA and are depolarized by GABA, which may constitute the basis for a paracrine signal among neuronal progenitors to dynamically regulate their proliferation and/or migration.

Adenosine Triphosphate↗
PubMed2003

Biophysical properties and ionic signature of neuronal progenitors of the postnatal subventricular zone in situ.

Previous studies have reported the presence of neuronal progenitors in the subventricular zone (SVZ) and rostral migratory stream (RMS) of the postnatal mammalian brain. Although many studies have examined the survival and migration of progenitors after transplantation and the factors influencing their proliferation or differentiation, no information is available on the electrophysiological properties of these progenitors in a near-intact environment. Thus we performed whole cell and cell-attached patch-clamp recordings of progenitors in brain slices containing either the SVZ or the RMS from postnatal day 15 to day 25 mice. Both regions displayed strong immunoreactivity for nestin and neuron-specific class III beta-tubulin, and recorded cells displayed a morphology typical of the neuronal progenitors known to migrate throughout the SVZ and RMS to the olfactory bulb. Recorded progenitors had depolarized zero-current resting potentials (mean more depolarized than -28 mV), very high input resistances (about 4 GOmega), and lacked action potentials. Using the reversal potential of K+ currents through a cell-attached patch a mean resting potential of -59 mV was estimated. Recorded progenitors displayed Ca2+-dependent K+ currents and TEA-sensitive-delayed rectifying K+ (KDR) currents, but lacked inward K+ currents and transient outward K+ currents. KDR currents displayed classical kinetics and were also sensitive to 4-aminopyridine and alpha-dendrotoxin, a blocker of Kv1 channels. Na+ currents were found in about 60% of the SVZ neuronal progenitors. No developmental changes were observed in the passive membrane properties and current profile of neuronal progenitors. Together these data suggest that SVZ neuronal progenitors display passive membrane properties and an ionic signature distinct from that of cultured SVZ neuronal progenitors and mature neurons.

Animals↗
PubMed1995

FISH in the evaluation of pleural and ascitic fluids.

Pleural and ascitic fluids (PAF) are complications of both nonmalignant and malignant conditions, such as congestive heart failure and chronic infections, as well as neoplasias, such as mesothelioma, lymphoma, and adenocarcinomas of the lung, ovary, endometrium, breast, colon, stomach, and pancreas. Differentiation between malignant and nonmalignant PAF is not always easy to assess on the basis of clinical, cytologic, and other criteria. A review of the chromosomal anomalies in neoplasms which can cause PAF revealed aneusomies of chromosomes 1, 3, 7, 8, 10, and 11 in about 40% to 80% of these malignancies. We performed FISH using centromere-specific probes for chromosomes 1, 3, 7, 8, 10, and 11 and chromosomal analysis on PAF cells from 21 patients, including 3 with ovarian cancer, 2 with lymphoma, 5 with adenocarcinoma of unknown origin, 1 with breast cancer, and 10 with atypical lymphocytosis of unknown cause. The results indicate a) a high correspondence between FISH and the clinical diagnosis (9 of the 11 cases of malignant fluid showing FISH abnormalities); b) that FISH is more sensitive than cytogenetics in detecting abnormal clones (10 vs. 6); and c) that FISH is a valuable adjunct to cytology in the interpretation of atypical lymphocytosis (3 of the 10 cases were shown to be abnormal by FISH). Thus, the FISH technique can be a very useful adjunct to conventional cytogenetics in yielding crucial information on the origin of PAF.

Ascitic Fluid↗
PubMed1994

Regulation of RAG-2 protein expression in avian thymocytes.

The recombinase-activating genes, RAG-1 and RAG-2, have been shown to be necessary to initiate the process of V(D)J recombination during the ontogeny of lymphocytes. While much is known about the end products of this rearrangement process, little is known about the function or regulation of the components of the recombinase system. To this end, we have generated a monoclonal antibody to the chicken RAG-2 protein. Chicken thymocytes were found to express high levels of RAG-2, part of which is phosphorylated. Within thymocytes, RAG-2 is expressed primarily within the nucleus. RAG-2 protein levels are high in the CD4- CD8- and CD4+ CD8+ immature thymocytes but absent at the single-positive CD4+ CD8- or CD4- CD8+ stage of thymocyte development. Mitogenic stimulation of thymocytes with phorbol myristate acetate and ionomycin results in down-regulation of RAG-2 expression. Consistent with these data, in vivo levels of RAG-2 are markedly lower in proliferating thymocytes than in smaller, G0/G1 cells. Down-regulation of RAG-2 expression appears to occur before cells enter S phase, suggesting that RAG-2 function may be limited to noncycling cells.

Animals↗
PubMed1993

Immunohistochemical localization of transforming growth factor alpha in the major salivary glands of male and female rats.

The three major salivary glands of normal male and female Fischer 344 rats of different ages were examined for the localization of epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) by immunohistochemical staining. EGF was demonstrated only in the granulated convoluted tubule (GCT) cells of the submandibular gland, the results confirming the previous reports, and most abundantly in adult males and pregnant females. TGF alpha stain was localized in all three glands and was found throughout the entire duct system, excluding acinar cells. The myoepithelial cells of the sublingual gland were also reactive with the TGF alpha antibody. The specificity of the staining was confirmed by negative staining reaction with the absorbed antibody and by radio-immunoassay and Western blot methods. This is the first report describing the presence of TGF alpha in the rat salivary glands.

Animals↗
PubMed1992

Multiple sclerosis masquerading as a mass lesion.

Six patients presenting with new neurological deficits underwent magnetic resonance imaging (MRI) that displayed mass lesions leading to diagnoses of tumor or abscess. Biopsy revealed demyelinating lesions.

Adolescent↗
PubMed1991

Generalized cortical dysplasia. Clinical and pathologic aspects.

Three children with profound mental retardation and intractable seizures died at ages 10 months, 3 years, and 7 years, respectively. Complete examination of their brains showed generalized cortical dysplasia, without any major malformation of the external gyral pattern. The neuropathologic features of cortical dysplasia include abnormally thickened cortex with indistinct demarcation of the gray-white matter junction. In many areas, the cortex contained increased numbers of large neurons with disordered cortical lamination. Heterotopic neurons were scattered throughout the white matter with decreased myelination of the underlying white matter. To our knowledge, these cases represent the first fully detailed neuropathologic study of diffuse cortical dysplasia--a newly recognized entity of abnormal neuronal migration.

Cerebral Cortex↗
PubMedDate not supplied

Serial MRI and CT findings in infantile Krabbe disease.

Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive childhood disorder characterized by severe motor and mental deterioration. The disease has been divided into 3 main types and further subdivided into several subtypes based on age of onset and symptoms. Initial clinical findings and magnetic resonance imaging (MRI) with several follow-up scans are presented to identify the order and extent of white matter involvement and developing brain atrophy in a child with the floppy infant variant of Krabbe disease. When the patient's clinical condition proceeded to stage 2, MRI disclosed severe involvement of the deep white matter around the atria and posterior limbs of the internal capsules. At the same time there was progression of normal myelination around the frontal horns. At age 32 months, the patient's clinical condition proceeded to stage 3; she did not interact with her environment. MRI revealed a significant decrease of white matter volume, generalized atrophy, and abnormal high signal in all white matter areas except the anterior limbs of the internal capsules. At the same time the volume of the central gray nuclei was decreased and also demonstrated abnormal high signal. Despite its sensitivity, MRI could not differentiate the findings of this variant of Krabbe disease from the classic form; therefore, subclassifications of Krabbe disease should be made on clinical grounds because they cannot be distinguished by biochemical or radiologic (MRI) criteria.

Brain↗