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Biomedical subjects

L C Ang

Publications and source records attributed to L C Ang.

At least 55 records · Page 3Linked to original sources
PubMed1994

Unilateral Creutzfeldt-Jakob disease presenting as rapidly progressive aphasia.

A 64-year-old man presented with a three day history of progressive Broca's aphasia, followed within 3 weeks by exclusively right-sided myoclonus, rigidity, and dystonia. Within 4 weeks he was globally aphasic. He died within 7 weeks of onset. In the final week, rigidity and myoclonus became bilateral. CT and MRI were normal. SPECT showed diminished perfusion of the left hemisphere. EEG showed periodic discharges on the left. At autopsy, there were marked cortical spongiform change, neuronal loss, and gliosis throughout the left hemisphere and in the right occipital cortex. Elsewhere in the right hemisphere, spongiform change was non-existent to minimal. There was moderate spongiform change in the molecular layer of the cerebellar cortex, much more marked on the left. Clinical and pathological unilateral cerebral predominance extended to the ipsilateral cerebellum. Creutzfeldt-Jakob disease is an important consideration in patients with rapidly progressive unilateral cerebral signs associated with a movement disorder.

Aphasia, Broca↗
PubMed1994

Regional brain activity of free radical defense enzymes in autopsy samples from patients with Alzheimer's disease and from nondemented controls.

Several lines of evidence support the hypothesis that oxygen free radicals are involved in the destruction of neurons in various degenerative disorders of the central nervous system. The activities of superoxide dismutase, catalase and glutathione peroxidase, three enzymes that contribute to the cellular defenses against free radical damage, were measured in different areas of autopsy brains from patients with Alzheimer's disease and from age matched controls. All brains were removed within 24 hours of the time of death and were cut in half sagitally. One half was stored frozen at -86 degrees C and the other half was examined histologically to confirm the presence or absence of Alzheimer's disease. Samples were taken from the frozen half for the enzyme assays. In control brains, the activity of superoxide dismutase is significantly higher in the cerebellum, frontal cortex and hippocampus than it is in the temporal cortex, parietal cortex and entorhinal cortex. The activity of catalase is significantly higher in cerebellum and frontal cortex than in hippocampus, parietal cortex and entorhinal cortex. Glutathione peroxidase activity is uniform across all brain areas studied. In Alzheimer's brains, superoxide dismutase activity is not statistically different among the various brain regions studied, but it is significantly lower than control in the cerebellum (-27%), frontal cortex (-27%) and hippocampus (-35%). Catalase is significantly higher in Alzheimer's cerebellum, frontal cortex and temporal cortex than in Alzheimer's hippocampus, parietal cortex and entorhinal cortex. However, there are no significant differences in catalase activity between Alzheimer's and control samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Alzheimer Disease↗
PubMed1993

Aluminum pretreatment impairs the ability of astrocytes to protect neurons from glutamate mediated toxicity.

A number of laboratories have shown that astrocytes protect neurons from glutamate excitotoxicity. The experiments described in this paper were designed to address the question whether prior exposure of astrocytes to aluminum (in the form of aluminum citrate) interfered with the ability of astrocytes to protect neurons from glutamate excitotoxicity. Our culture paradigm consisted of highly enriched cultures of neurons and astrocytes grown on separate coverslips; this design enables one to subject either the neurons or the astrocytes to specific treatments and recombine the cells into the same petri dish simply by moving coverslips from dish to dish. We have confirmed findings of other laboratories that astrocytes could protect neurons from glutamate-induced death when glutamate (100 microM) is added to the culture medium. We have also demonstrated that prior treatment of astrocytes with 100 microM aluminum citrate impairs this ability of astrocytes to promote neuronal survival. No differences, however, were observed in the ability of control and aluminum-treated astrocytes to take up glutamate. These findings suggest that aluminum may cause astrocytes to: (i) secrete a factor that makes neurons more susceptible to glutamate-induced toxicity; (ii) secrete a neuronotoxic factor in the presence of glutamate; or (iii) reduce secretion of a factor that protects neurons from glutamate excitotoxicity.

Aluminum↗
PubMed1993

Neurite promoting activity of insulin, insulin-like growth factor I and nerve growth factor on spinal motoneurons is astrocyte dependent.

Mouse motoneurons were isolated from dissociated E15 mouse spinal cord and grown on polyornithine-coated round coverslips in a growth medium (DMEM/F12) supplemented with progesterone, trans-ferrin, selenium, horse serum and muscle extract. Astrocytes from newborn mouse neopallium were grown on rectangular coverslips. The motoneuron neurite growth was determined at day 8 of culture by counting, using the light microscope, the intersections produced by neurites radiating from the perikaryon placed centrally in a graticule eyepiece of concentric circles. The mean intersections for cultures without addition of astrocytes, insulin, insulin-like growth factor I (IGF-I) or nerve growth factor (NGF) was 12.6 +/- 0.8. When astrocytes on a separate coverslip were introduced from day 1, there was a small increase in neurite growth (16.3 +/- 0.9). The neurite growth was further increased significantly with the addition of insulin (27.3 +/- 1.4), IGF-I (31.5 +/- 1.4) or NGF (21.8 +/- 1.1) to cultures with astrocytes. Insulin, IGF-I or NGF in the absence of astrocytes did not greatly increase the neurite growth. We conclude that insulin, IGF-I and NGF promote neurite growth through some interactions with astrocytes.

Animals↗
PubMed1993

Chromogranin A, a soluble synaptic vesicle protein, is found in cortical neurons other than previously defined peptidergic neurons in the human neocortex.

Neuropeptides in the cerebral cortex have previously been identified in non-pyramidal neurons only. By comparing the location of chromogranin A (CgA), a soluble protein of large dense-core synaptic vesicles, with that of SMI-32, neuropeptide Y (NPY), parvalbumin (PV) and calbindin (CaBP) using double label immunohistochemistry, we demonstrate that CgA is present in pyramidal neurons as well as in several subtypes of non-pyramidal neurons.

Adult↗
PubMed1993

Central neurocytoma: report of 2 cases and literature review.

Two cases of central neurocytoma are presented. This is a rare CNS tumour affecting, predominantly, young individuals. There is enough evidence in the literature now to distinguish this entity clinically, radiologically and histologically. Much less is known about the management of patients with this tumour, because most of the reports are in pathological literature. Using our two cases and reviewing the available literature, we are endeavouring to shed light on the clinical aspects and management of central neurocytoma. In particular, we attempted to evaluate the role of surgical excision and radiation therapy in the management of this tumour.

Adolescent↗
PubMed1993

Fahr's disease associated with astrocytic proliferation and astrocytoma.

This report documents the neuropathological findings of astrocytic proliferation and astrocytoma in a patient with Fahr's disease. At autopsy, there was extensive bilateral symmetrical calcification involving basal ganglia, sulcal depth of the cerebral cortex, and dentate nuclei of the cerebellum. A large low-grade astrocytoma was identified in the left parietal lobe. Astrocytic proliferation was also noted in the areas of early calcification and at the margins of large calcareous deposits, away from the tumor.

Adult↗
PubMed1993

A simple, yet versatile, co-culture method for examining neuron-glia interactions.

There is increasing interest in examining neuron-glial interactions in the developing and the mature central nervous system. Here, we describe a system that allows examination of interactions mediated by diffusible molecules even when such interactions involve more than 2 cell populations. Our procedure involves culturing highly enriched populations of neurons and glial cells on separate coverslips. Such coverslips can be readily moved from one petri dish to another, thus enabling the investigator to subject the neurons and the glial cells to different experimental manipulations. The coverslips can then be placed in any desired combination within a petri dish. This gives one great flexibility in examining neuron-glial interactions. Using this approach, we unequivocally demonstrate that astrocytes protect neurons from glutamate excitotoxicity.

Animals↗
PubMed1993

Epilepsy and bathtub drowning. Important neuropathological observations.

Drowning is a well-recognized cause of death in persons with epilepsy. Investigation of bathtub drowning is often not straightforward. We report three cases of bathtub water drowning of patients with neuropathological bases for seizures. The importance of neuropathological examination is discussed. A high index of suspicion is required for all cases of bathtub-related death, even in the absence of history of previous seizure disorders. Neuropathological examination must be performed to look for anatomical lesions associated with seizures. Identification of these findings could be very helpful in ruling out homicide or suicide as the cause of death in bathtub drownings.

Adult↗
PubMed1993

Polymyositis with plasma cell infiltrate in essential mixed cryoglobulinaemia.

A patient with essential cryoglobulinaemia who presented with polymyositis is described. Muscle biopsy showed intense plasma cell infiltration of muscle. Plasmapheresis produced a rapid resolution of the cutaneous manifestations of the disease, but little improvement in muscle strength. Oral steroids resulted in moderate improvement in muscle strength. There have been no previously reported cases of polymyositis in association with essential cryoglobulinaemia.

Administration, Oral↗
PubMed1992

Delayed changes of chromogranin A immunoreactivity (CgA ir) in human striate cortex during postnatal development.

The changes in chromogranin A expression in the human striate cortex from birth till 67 years were studied by immunohistochemical method in 18 autopsied patients. The first chromogranin A immunoreactivity (CgA ir) was identified at birth in layer IV (especially IVc) mainly as fine nerve terminals. By 6 months, the first perikaryal reactivity was noted in the large pyramidal neurons of layer V. The smaller neurons in layers IV, V and VI showed a progressive increase in CgA ir from 15 months to about 17 years. At approximately 9 years, immunoreactivity began to be noted in supragranular neurons in layers II and III. The final laminar distribution of CgA ir seemed to be attained at about 25 years with relatively little change thereafter. The CgA ir in the striate cortex demonstrates a prolonged period of developmental changes, lasting from birth to about 25 years.

Adolescent↗
PubMed1992

Effects of astrocytes, insulin and insulin-like growth factor I on the survival of motoneurons in vitro.

We isolated motoneurons from E15 dissociated mouse spinal cord by density centrifugation and planted them onto poly-ornithine-coated coverslips in a growth medium (DMEM/F12) supplemented with progesterone, transferrin, selenium, horse serum and muscle extract. Under these conditions only 28% of the motoneurons survived for 8 days. When living astrocytes on a separate coverslip were introduced into dishes containing motoneurons, there was a two-fold increase in neuronal survival. The addition of insulin and insulin-like growth factor I (IGF-I) to such cultures alone or together, still further increased motoneuron survival, but this did not happen in the absence of astrocytes. We conclude that (a) astrocytes exert a trophic role in the survival of spinal motoneurons, (b) the effect does not require physical contact of the cells, and (c) insulin and IGF-1 have neurotrophic activity for motoneurons, an effect possibly mediated by living astrocytes.

Animals↗
PubMed1992

Malignant rhabdoid tumor of the central nervous system with subarachnoid dissemination.

A case of primary central nervous system malignant rhabdoid tumor is presented. Clinical, radiological, and histopathological findings are described in detail. Because of a relatively long clinical course after presentation, it was possible to assess the clinical and radiological response to different treatment modalities: surgery, chemotherapy, and radiotherapy. Despite the complete clinical and radiological response that was achieved after subtotal excision, two cycles of chemotherapy, and high-dose radiotherapy, the tumor recurred within 4 months of completion of the treatment, with wide subarachnoid dissemination. Radiotherapy treatment of whole cranial axis is recommended.

Brain Neoplasms↗
PubMed1992

Results of meniscal surgery of the knee.

From 1988 to 1990, eighty operations on eighty knees of seventy-nine patients with a clinical diagnosis of meniscal tear was entered into a prospective study. The clinical diagnosis was correct in 76% of patients. Excellent or good results were achieved in 90% of knees which had only meniscal lesions but dropped to 70.5% when other intraarticular pathologies coexisted with the meniscal lesions. Excellent or good results were achieved in 71% of the knees in the presence of Anterior Cruciate Ligament (ACL) deficiency.

Adolescent↗
PubMed1991

Motoneuron survival in vitro: effects of pyruvate, alpha-ketoglutarate, gangliosides and potassium.

When grown in a serum and muscle extract containing medium, about 20% of chick motoneurons survived for one week. The presence of pyruvate during the first hour of culture doubles the number of motoneurons that survive. The subsequent addition of 5 mM alpha-ketoglutarate, 10-20 mM potassium, or 100 microM GM1 ganglioside results in a further increase in motoneurons surviving. These effects of alpha-ketoglutarate, potassium and GM1 ganglioside are not additive. Using such compounds in the culture medium, one can have a three-fold increase in the survival of motoneurons.

Animals↗
PubMed1991

SMI-32 immunoreactivity in human striate cortex during postnatal development.

SMI-32, an antibody which recognizes the non-phosphorylated epitopes on the neurofilament proteins was used to study the morphological changes in the human striate cortex during postnatal development. Striate cortices from 12 autopsied patients with ages ranging from 1 day to 70 years were obtained. Using the avidin-biotin-peroxidase method, the first SMI-32 immunoreactive neurons were identified at sublayers Vb/VIa on the first postnatal day. At 5 months, the next group of neurons to develop immunoreactivity were in IVb. By 15 months, SMI-32 immunoreactive neurons were observed at III, IVa, IVb, V and VI. The changes in SMI-32 immunoreactivity (ir) were stabilized from 3 years and after. The SMI-32 ir in the striate cortex could be a useful morphological correlate for studying developmental diseases affecting the neocortex.

Adult↗
PubMed1991

Immunolocalization of prealbumin (transthyretin) in renal cell carcinoma.

Fourteen primary and nine metastatic renal cell carcinomas were examined with a commercially available antibody against prealbumin (transthyretin) using the avidin-biotin-peroxidase complex (ABC) technique. Twenty-two of the 23 tumours expressed prealbumin, and in 16 of them more than 50% of the tumour cells showed immunoreactivity. The same tumours were subjected to immunostaining with antibodies against low molecular weight keratin, carcino-embryonic antigen, S-100 protein and epithelial membrane antigen for comparison. We conclude that prealbumin, which was absent in 14 adenocarcinomas from other organs, should be included in the panel of markers for differentiating metastatic adenocarcinoma of renal origin from those of other primary tumours.

Carcinoma, Renal Cell↗