Biomedical subjects

N R Ghatak

Publications and source records attributed to N R Ghatak.

At least 37 records · Page 2Linked to original sources

PubMed1988

Acid alpha-neuraminidase deficiency: a nephropathic phenotype?

Isolated neuraminidase deficiency is a member of the relatively rare group of storage disorders known as glycoproteinoses. We report the long-term natural history of the disease in one of the first patients described in the literature. An unusual feature of the disease is the abrupt onset and fulminant nature of the nephrotic syndrome, complications of which caused the demise of our patient. Pathological examination of the kidneys from this child revealed renal epithelial cell damage, most marked in the membranes of the glomeruli and proximal tubules, findings which are consistent with the high sialic acid content of the membrane in these areas of the nephron. Chemical analysis indicated that the bulk of the stored material in the kidney was in the form of polar sialyloligosaccharides of high molecular weight. On the basis of our experience, as well as the previous reports of neuraminidase-deficient patients with nephropathy, we propose a nephropathic phenotypic variant of type 2 infantile sialidosis.

Brain↗

PubMed1987

Diagnosis of progressive multifocal leukoencephalopathy by brain biopsy with biotin labeled DNA:DNA in situ hybridization.

DNA:DNA in situ hybridization using a cloned JC virus (JCV) DNA probe labeled with biotin confirmed the presence of JCV DNA in formalin-fixed, paraffin-embedded brain biopsies from four cases of progressive multifocal leukoencephalopathy (PML). Only small pieces of tissue were available in each case. Detection of the JC DNA:DNA hybrids was carried out by affinity cytochemistry. JCV DNA was identified predominantly in the nuclei of interfascicular oligodendrocytes in demyelinated areas of the biopsies. JC virus was isolated from one case, and the diagnosis of PML was substantiated in all cases by electron microscopic identification or immunocytochemical labeling of JC viral antigen. In situ hybridization using a biotin labeled JCV DNA probe is a specific, sensitive and convenient method for confirming the diagnosis of PML in suspected cases evaluated by brain biopsy.

Adult↗

PubMed1987

CT-guided stereotactic biopsies of lesions in the medulla and a case of Leigh's disease.

CT-guided stereotactic biopsy of lower brain stem lesions in 7 consecutive cases is discussed. A frontal transincisural approach was used. Five patients had astrocytomas histologically. The single patient who had undergone empirical radiation therapy prior to tissue diagnosis revealed only necrosis. One patient was found to have pathology suggestive of Leigh's disease. This patient was not radiated and is the first alive adult to have this diagnosis confirmed. Although controversy still exists in the management of brain stem lesions, we intend to demonstrate the value of tissue diagnosis in the management of such lesions.

Adult↗

PubMed1986

Anterior horn changes of motor neuron disease associated with demyelinating radiculopathy.

Morphologic study of the spinal cord of a patient with generalized motor deficits revealed changes in the anterior horns characterized by the selective loss of large motor neurons, gliosis and the abnormal accumulation of 10 nm filaments which appeared as argyrophilic spheroids in the perikarya and axons of motor neurons. The ventral roots were predominantly affected and showed a variable loss of axons. The remaining axons displayed prominent onion-bulb formations, frequent axonal sprouting and occasionally evidence of active demyelination. The coexistence of a demyelinating motor radiculopathy and anterior horn changes simulating those of amyotrophic lateral sclerosis (ALS) may contribute to our understanding of the unresolved question of whether the neuronal perikaryon or its axon is the primary target in the pathogenesis of ALS. These observations also indicate that a rigid separation of pathogenetic mechanisms into neuronopathy, axonopathy and myelinopathy may not be always possible.

Axons↗

PubMed1985

Xanthogranulomatous colloid cyst of the third ventricle.

This is a case report of a xanthogranulomatous colloid cyst of the 3rd ventricle. Possible etiologies for this rare entity, along with the clinical problems that may be associated with it, and the differential diagnosis are discussed.

Adult↗

PubMed1982

Glial outgrowth along spinal nerve roots in amyotrophic lateral sclerosis.

Formation of glial bundles in the proximal portion of the ventral nerve roots is described in a 51-year-old patient with the sporadic form of amyotrophic lateral sclerosis (ALS). Although the bundles were relatively fewer, they were identical in morphology and distribution to those consistently found in Werdnig-Hoffmann disease (WHD). The occurrence of glial bundles in ALS, albeit rare, indicates that this phenomenon is not a unique feature of WHD. Similar changes have been observed in several other unrelated conditions, always in association with degeneration of neurons or axons. Thus, outgrowth of astrocytes in the form of glial bundles should be considered a special type of astrocytic reaction at the interface of the central and peripheral nervous systems.

Amyotrophic Lateral Sclerosis↗

PubMed1981

Morphology and distribution of cytoplasmic inclusions in adrenoleukodystrophy.

We report some additional observations on the pathognomonic cytoplasmic inclusions in a typical case of adrenoleukodystrophy (ALD). Study of the linear inclusions by means of tilt-stage electron microscopy indicated that they represent trilaminar sheet-like structures distinct from materials seen in various other storage disorders. This study emphasizes that the inclusions in the adrenal and testicular parenchymal cells morphologically differ from those in the brain macrophages. In the latter they occur as membrane-bound discrete structures while in the parenchymal cells they are always seen lying free in the cytoplasm and associated with cleft-like spaces. This morphologic variation of the inclusions is noteworthy and probably reflects a biochemical difference in the storage materials in these two most severely affected organs. In addition, this study demonstrates the presence of linear inclusions within macrophages in otherwise normal-appearing liver, spleen, thymus and also in the renal tubular cells. These findings suggest that the abnormal materials containing very long chain fatty acids enter the blood stream and become sequestered in the reticuloendothelial system and possibly are also excreted in the urine. Detection of these abnormal fatty acids in blood and urine may simplify diagnosis of ALD.

Adolescent↗

PubMed1981

Contrast enhancement in the postoperative brain.

Contrast enhancement simulating an abscess or residual tumor has been described in postoperative cranial computed tomography (CT) scans. This study was undertaken to determine the cause of this contrast enhancement by using canine brain as an experimental model. Sequential CT scanning was performed with and without contrast enhancement following partial resection of the right hemisphere, and the CT findings were correlated with the histological changes. Findings indicate that enhancement of the surgical margin is related both temporally and spatially to the neovascularity following surgery. The ring-like enhancement around the surgical margin is seen best at two to four weeks after surgery, and may simulate an abscess. However, edema seen around an abscess in adjacent brain is absent or minimal in the case of postoperative enhancement during this period, and this feature should help differentiate these entities.

Animals↗

PubMed1981

Mechanism of cerebral arteriolar abnormalities after acute hypertension.

Acute severe hypertension induced by intravenous norepinephrine or angiotensin in anesthetized cats equipped with a cranial window caused prolonged arteriolar vasodilation associated with reduced responsiveness to arterial hypercapnia or hypocapnia and passive response to changes in arterial blood pressure. Scanning and transmission electron microscopy of such pial arterioles showed discrete destructive endothelial lesions the density of which correlated with the degree of vasodilation. Abnormalities of the vascular smooth muscle were seen in all dilated arterioles but affected only a small number of smooth muscle cells. The oxygen consumption of pial arterioles from cats subjected to hypertension was significantly reduced in comparison to that of vessels from normal animals. The arteriolar abnormalities induced by hypertension were inhibited by pretreatment with inhibitors of cyclooxygenase (indomethacin or AHR-5850) or by topical application on the brain surface of scavengers of free oxygen radicals (mannitol or superoxide dismutase). The results suggest that the mechanism of the arteriolar abnormalities from acute hypertension involves a sudden increase in prostaglandin synthesis that leads to generation of free oxygen radicals.

Animals↗

PubMed1980

Pathologic findings in mucopolysaccharidosis type IIIB (Sanfilippo's sydnrome B).

The pathologic changes in a rare case of mucopolysaccharidosis (MPS) type IIIB or Sanfilippo's syndrome B (absence of alpha-N-acetylglucosaminidase) are presented, along with the biochemical findings. Comparisons were made with other reported cases of MPS III subtypes and related storage disorders in terms of clinical, light microscopic, electron microscopic, and chemical findings, and a correlation of the ultrastructural changes made with the severe neurological dysfunction noted in this disorder. At present, MPS III subtypes cannot be separated from one another by morphological means because the same expression and distribution of lesions may be encountered among differing subtypes.

Adolescent↗

PubMed1980

Neurofibrillary pathology in progressive supranuclear palsy.

We describe the fine structure of the subcortical neurofibrillary tangles (NFT) in 2 cases of progressive supranuclear palsy (PSP). In case 1 (69-year-old man) about one half of the NFT in the midbrain and pons examined were composed of 13-16 nm straight filaments and the other were made up of paired helical filaments (PHF) of Alzheimer type. The NFT in case 2 consisted of straight tubules with infrequent segments of unusual twisted fibril of unknown nature. The simultaneous occurrence of straight and PHF in one of these cases suggests that the NFT in PSP may be similar to those of Alzheimer type occurring in various conditions.

Aged↗

PubMed1980

Postoperative computed tomographic changes in the brain: an experimental study.

Contrast enhancement in the brain on computed tomography (CT) after an operation was studied in otherwise healthy dogs to evaluate the stages of enhancement caused by surgical changes. Serial CT scanning was done with and without contrast enhancement following a partial posterior parietal lobectomy. Pathologic correlation was obtained. Contrast enhancement occurred as early as one week, with peak incidence occurring between two and six weeks. Enhancement was diminishing or absent by the eight week after operation. Separate components of enhancement secondary to breakdown of the blood-brain barrier and to vascular granulation tissue may be distinguishable.

Animals↗

PubMed1979

Lewy bodies in the presence of Alzheimer's disease.

Large numbers of Lewy bodies in the substantia nigra were found in a case of Alzheimer's disease. Parkinsonian symptoms were not recognized. The patient appears to be an example of an association recognized by Woodard but not yet understood. The case is discussed in the context of reported relationships between Parkinson's disease or "Lewy body disease" and dementia, on the one hand, and reports linking various forms of psychoses with an unusually high incidence of Lewy bodies, on the other.

Aged↗

PubMed1979

Fenestrated blood vessels in human skeletal muscle.

In a fine structural study of 32 skeletal muscle biopsies, rare examples of fenestrated blood vessels (FV) were found in three cases. In view of similar observations reported in a case of Duchenne muscular dystrophy, it is suggested that FV albeit rare may occur in skeletal muscle at least under pathologic conditions. These aberrant FV may be derived from adjacent dermis and/or epineurium which are known to contain occasional FV. Alternatively, the occurrence of fenestrae may reflect a nonspecific alteration in pre-existing continuous endothelium. The significance, if any, of their presence in skeletal muscle is unknown.

Adult↗

PubMed1978

A morphologic study of opportunistic cerebral toxoplasmosis.

The morphology of toxoplasma and its interaction with the cellular elements of the brain were studied in a patient who dies of extensive cerebral toxoplasmosis superimposed on Hodgkin's disease. The cerebral lesions were devoid of inflammatory cellular response and contained numerous organisms mostly in isolated multiplying forms in neurons, glia and vascular walls. Encysted forms containing multiplying organisms were seen infrequently. Intracellular parasite was identified in normal-appearing neuropil. The mode of multiplication and cyst formation of toxoplasma appeared basically similar to that described under experimental conditions. In addition, a rapid evolution of the cerebral lesions was suggested by computerized tomography. This study suggests that tissue necrosis in human cerebral toxoplasmosis is the result of an increased rate of multiplication and enhanced cellular invasiveness of the parasite most likely related to impaired cellular immunity as has been postulated by clinical and experimental data.

Aged↗

PubMed1978

Light and electron microscopic observations on a ganglioneuroma.

This report describes some additional morphologic observations on a mediastinal ganglioneuroma. The neoplastic neurons contained argentaffin cytoplasmic granules presumably representing neurosecretory granules. Cytoplasmic inclusions resembling Pick's bodies were frequently observed in the neuronal components of the tumor. These inclusions consisted of neurofilaments mixed with a variable number of microtubules, dense core vesicles and other organelles. These findings expand the range of conditions in which Pick's bodies are found.

Child↗

PubMed1978

An unusual intraspinal connective tissue mass.

The fine structure of a surgically excised intradural spinal mass is described. The mass was essentially composed of giant collagent fibers measuring up to 500 nm or more in diameter. In addition, small collections of collagen fibers with unusual cross banding pattern were occasionally observed. The precise nature of this apparently unique lesion simulating an intraspinal tumor remains undetermined.

Adult↗

PubMed1978

Spinal roots in Werdnig-Hoffmann disease.

The spinal nerve roots were studied in two siblings with Werdnig-Hoffmann disease (WHD). An invasion by fibrous astrocytes was consistently seen along the atrophic ventral roots, more extensively in the older sibling. The parallel glial processes extended in discrete bundles and were always enclosed by a basal lamina. Loss of unmyelinated axons and probable glial extension along unmyelinated fibers were also seen. The astrocytic processes with abundant microtubules and prominent junctional devices resembled those of the subpial region, which appeared to have gained access into the ventral roots following axonal degeneration. The present observations suggest that such glial migration, although apparently unique in WHD, is a secondary phenomenon and fails to resolve the issue as to whether neuronal degeneration or an injury to the nerve roots is the primary event in this disorder.

Astrocytes↗