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Biomedical subjects

M M Arnold

Publications and source records attributed to M M Arnold.

18 recordsLinked to original sources
PubMed2006

Age-dependent modulation of hippocampal long-term potentiation by antioxidant enzymes.

Oxidative stress has long been associated with normal aging and age-related neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). However, it is now evident that reactive oxygen species (ROS) such as superoxide (O(2-*)) and hydrogen peroxide (H(2)O(2)) also play pivotal roles in normal cell signaling. The focus of the present study was to examine the effects of the antioxidant enzymes CuZnSOD (SOD1) and catalase, which produce and remove H(2)O(2), respectively, on long-term potentiation (LTP) forms of synaptic plasticity during aging. Consistent wth previous studies, LTP, when induced in vitro in CA1 of the hippocampus with a high-frequency stimulation protocol, is significantly reduced in slices from older mice (22-26 months) relative to younger mice (2-4 months). Neither knockout of the endogenous catalase gene (Cat KO) nor acute enzymatic treatment with SOD1 altered LTP in slices from adult mice. Conversely, enzymatic applications of SOD1 inhibited LTP in slices from older mice. A much different set of results emerges with exogenous applications of catalase to hippocampal slices. Catalase significantly inhibited LTP in slices from adult mice but reversed age-related LTP deficits in slices from older mice. Measurements of H(2)O(2) showed that exogenous treatments with catalase lowered H(2)O(2) in synapse-enriched synaptoneurosome (SN) fractions prepared from adult mice. Notably, SNs from both Cat KO and old mice were deficient in removing extracellular challenges of H(2)O(2). Overall, the results suggest that dynamic alterations in extracellular H(2)O(2) metabolism affect synaptic plasticity in the hippocampus during aging.

Aging↗
PubMed1997

Stiff-persons' syndrome associated with thymoma and subsequent myasthenia gravis.

We report the first case of stiff-persons' (-man) syndrome in the setting of a histologically proven thymoma. Muscular hyperactivity was abolished under general anesthesia and the symptoms of stiffness resolved after thymectomy and three courses of intravenous immunoglobulins. After thymectomy, the patient developed ocular myasthenia gravis which later resolved spontaneously. We suggest that thymoma be sought for in cases with neuromuscular hyperactivity syndromes. Myasthenia gravis may develop subsequently in these cases.

Electromyography↗
PubMed1996

Effects of fixation and tissue processing on immunohistochemical demonstration of specific antigens.

Identification of biomarkers in archival tissues using immunochemistry is becoming increasingly important for determining the diagnosis and prognosis of tumors, for characterizing preinvasive neoplastic changes in glandular tissues such as prostate, for evaluating the response of tumors and preinvasive neoplastic changes to certain therapies (i.e., as a surrogate intermediate end point), for selecting patients who are candidates for specific therapies (e.g., immunotherapy) and for retrospective studies. For detecting specific biomarkers it is important to understand the limitations imposed by the fixation methods and processing of the tissues. This study was designed to determine the effects of fixation on the detection in archival paraffin blocks of selected antigens postulated to be important in tumor biology. We evaluated the antigens TGF alpha, p185erbB-2, broad spectrum keratins, p53, and TAG-72 (B72.3). Fixatives evaluated included standard preparations of neutral buffered formalin, acid formalin, zinc formalin, alcoholic formalin, ethanol, methanol, and Bouin's fixative. We found that in general neutral buffered formalin is the poorest fixative for maintaining antigen recognition by immunohistochemistry and that no single fixative was best for all antigens. The dehydrating (coagulant) fixatives (e.g., ethanol and methanol) preserved immunorecognition of p53 and broad spectrum keratins best while the slow cross-linking fixatives (e.g., unbuffered zinc formalin) were best for demonstrating TGF alpha and p185erbB-2. Fixatives other than neutral buffered formalin produced equivalent recognition of the epitope of TAG-72 by B72.3. In formalin fixed archival tissues, only a portion of the antigen signal can be detected by routine immunohistologic methods.

Antigens, Neoplasm↗
PubMed1996

Lymphoplasmacytic aortitis and acute aortic dissection. An uncommon association.

A 43-year-old white man with a history of cigarette smoking, hypertension, nephrolithiasis, and cervical degenerative arthritis was hospitalized for sudden-onset severe, substernal, and pleuritic chest pain with epigastric radiation. Despite evaluation, the cause remained unclear and the patient expired on hospital day 5. Autopsy revealed acute Stanford type A aortic dissection, hemopericardium, and hemothorax. Grossly, the aorta and its branches, including uninvolved medium-sized arteries, displayed extreme mural fragility. Microscopic examination showed a primary lymphoplasmacytic aortitis-periaortitis without giant cells. Rents within the tunica media, medial-adventitial inflammation, and elastic fiber disruption were limited to sites of gross aortic dissection. Muscular arteries showed patchy, chronic arteritis-periarteritis without giant cell infiltrate or aneurysm formation. This case documents an unusual association of primary lymphoplasmacytic aortitis and aortic dissection.

Adult↗
PubMed1996

Stage-specific expression of integrin alphaVbeta3 in neuroblastic tumors.

The ligand specificity of the integrin cell adhesion receptors probably determines the ability of specific integrins to promote tumor cell proliferation and metastasis. Therefore, we compared the expression of integrin alphaVbeta3, a promiscuous receptor that binds with high affinity to numerous cell matrix proteins, with the expression of integrin alphaVbeta5 and the integrin beta 1 subunit (which pairs with multiple alpha subunits) in neuroblastic tumors at various stages of differentiation. Undifferentiated neuroblastoma tumors rapidly invade and metastasize, whereas ganglioneuroblastomas rarely metastasize. Differentiating neuroblastomas are associated with an intermediate prognosis. Paraffin sections of neuroblastic tumors at various stages of differentiation obtained at biopsy from 17 patients were hybridized with antisense integrin subunit-specific alphaV, beta3, beta1, and beta5 riboprobes. All neuroblastic tumors and seven adrenal glands obtained at autopsy were analyzed immunohistochemically with antibodies directed toward the alphaV, beta3, beta1, and beta5 subunits. The alphaV subunit was expressed in neuroblastic tumors independent of the stage of differentiation, although mRNA and protein expression were generally weak in ganglioneuroblastomas, and was also detected in adrenal gland medullae. The beta1 subunit was detected in most neuroblastic tumors independent of the stage of differentiation as well as in adrenal gland medullae. In contrast, the beta3 subunit, which was not expressed in adrenal gland medullae, was expressed at the protein and mRNA levels in undifferentiated neuroblastomas (six of seven and seven of seven, respectively) but was not expressed in neuroblasts or ganglion cells in ganglioneuroblastomas (one case weakly positive out of five). The beta 5 subunit was expressed at the protein (five of five) and mRNA (four of five) levels in the ganglion cells of ganglioneuroblastomas and, although mRNA for this subunit was detectable in undifferentiated tumors, the protein was not detectable. The expression of integrin alphaVbeta3 in undifferentiated neuroblastomas may contribute to the rapid growth of these tumors and their tendency to metastasize.

Adolescent↗
PubMed1994

Evaluation of biomarkers in breast and prostate cancer.

p53, p185erbB-2, and epidermal growth factor (EGF) receptor are well-characterized biomarkers in invasive adenocarcinoma of the breast and in ductal carcinoma in situ. erbB-2 Protein (p185erbB-2) must be identified clearly on cytoplasmic membranes while cytoplasmic expression is ignored for breast cancers to be classified as overexpressing p185erbB-2. For p53, nuclear staining and the percent positive cells are considered, but rules for "cut-offs" are not defined. Evaluation criteria for biomarkers in prostate cancer are preliminary and the "rules" may not be the same as for breast cancer. Because the initial methods of fixation and tissue processing can change both the pattern and intensity of immunohistochemical identification of specific antigens and localization of receptors may change after the receptor-ligand interactions, we evaluated the effects of fixation both on the immunolocalization and intensity of expression of p53, p185erbB-2, and EGF receptor. We also studied the patterns of p185erbB-2 and p53 expression in a series of breast cancers evaluated concomitantly with a group of prostate cancers. Our results confirm that p53 mutations are common in breast cancer and that there is strong expression of p185erbB-2 on the membranes of a subset of breast cancers. The patterns of staining for both p53 and p185erbB-2 are different in prostate and breast cancers. A much lower proportion of prostate tumors than breast tumors have more than 10% of tumor cells with detectable nuclear p53 protein, but this proportion increases markedly in metastatic tumors or in primary stage D prostate cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1994

DNA image cytometric analysis of primary clear cell carcinoma of the liver.

Eleven cases of clear cell hepatocellular carcinoma were evaluated for DNA ploidy by means of image analysis of Feulgen-stained tissue sections. The tumors displayed a trabecular or solid pattern and contained between 40% and 90% clear cells. Five tumors (45.4%) were diploid and six tumors (54.5%) were nondiploid (four aneuploid, one tetraploid, and one multiploid). The diploid tumors had no significant pleomorphism or mitotic activity, whereas the nondiploid tumors displayed a moderate to severe degree of pleomorphism and high mitotic rate. In addition, the nuclear area of the aneuploid tumor cells (55.3 microns2 +/- 5.4%, mean +/- SD) was significantly larger than that of the control hepatocytes (43.3 microns2 +/- 6.8%) (P = .01) and that of the diploid tumor cells (39.5 microns2 +/- 5.5%) (P = .001). We conclude that clear cell carcinoma of the liver comprises two groups: one with bland morphologic features and diploid DNA content and the other with aggressive morphologic features and aneuploid DNA content. We suggest that this finding may explain the discrepant literature reports regarding the prognosis of this tumor.

Adult↗
PubMed1992

Distribution of Lipiodol and evidence for tumor necrosis in hepatocellular carcinoma.

To study the distribution and thromboembolic effect of Ultrafluid Lipiodol, 15 surgically removed hepatocellular carcinomas with selective intraarterial Lipiodol injection 7 to 10 days before surgery and 15 noninjected controls were studied radiologically and histologically. Tissue blocks were processed with an en bloc silver impregnation technique for Lipiodol localization in histologic sections. Lipiodol was distributed evenly in tumors measuring less than 5 cm in diameter and peripherally in tumors measuring 10 cm or more. Lipiodol droplets were mainly extracellular. There was no difference in tumor architecture or in hemorrhage and necrosis scores between Lipiodol-injected cases and negative controls (1.18 versus 0.92). Similarly, in injected cases, no differences were observed between Lipiodol-positive and Lipiodol-negative areas (scores of x-ray Lipiodol-positive versus Lipiodol-negative areas: 1.17 versus 1.36; scores of microscopic Lipiodol-positive versus Lipiodol-negative areas: 1.18 versus 1.14). Lipiodol-negative but hypodense areas examined by x-ray proved to be necrosis or fibrosis with or without viable tumor islands. Lipiodol has no thromboembolic effects. The uneven Lipiodol distribution may account for its failure as a carrier for chemotherapeutic agents in large tumors.

Carcinoma, Hepatocellular↗
PubMed1991

A radiological-pathological correlation of hepatocellular carcinoma (HCC).

The histological distribution of lipiodol within hepatocellular carcinoma (HCC) was correlated with that seen on computed tomography (CT), arteriography and high resolution plain films of 15 resected specimens. By means of special stains, the arterially administered lipiodol was shown to be maximally distributed at the periphery of large tumours and nodules. The centre of large lesions often remained unopacified. In multinodular tumours some nodules were heavily stained while others contained little or no contrast medium. In small tumours there was a more uniform distribution. In large tumours, those areas where there are large arteries (and slow flow) contained little or no lipiodol. There was also no consistent match of areas of angiographic blush with lipiodol deposition. The lipiodol patterns were poorly shown by CT when compared with high resolution films taken on a mammography unit. We conclude from this study that lipiodol on its own as an embolic agent or as a chemotherapeutic carrier has great limitations because of its peripheral and otherwise haphazard distribution in large tumours. However, such treatments might be more effective in small tumours where a greater concentration of lipiodol is likely. Nevertheless, lipiodol staining of tumours remains a useful diagnostic aid as small HCC can be difficult to visualize both on arteriography and conventional CT.

Adult↗
PubMed1991

Are the hepatic arteries "end arteries"?

Twenty-five autopsy livers were studied for intrahepatic arterial anastomoses. Under fluoroscopy, barium suspension at various concentrations, with or without latex, was injected into the hepatic artery. One-centimeter axial or coronal liver sections were radiographed with high-resolution mammographic technique. All films were reviewed. Seven interconnecting arterial pathways were demonstrated: subcapsular and peripheral arcades, proximal and intermediate connecting vessels, periportal arterial rete and ring, a fine parenchymal network, and connections with the gallbladder arterial system. In the six cases where a branch artery was occluded, arterial filling of the entire liver was demonstrated. The authors conclude that these interconnecting networks could account for the infrequency of hepatic infarcts, are the anatomic basis for the intrahepatic spread of malignant lesions, the "duplication" and "triplication" patterns on arteriography, and may account for the outer streaks of the arteriographic "thread and streak" sign in portal vein invaded by hepatocellular carcinoma.

Angiography↗
PubMed1991

Radiological-pathological correlation of mass lesions in the liver.

Thirty two human livers were removed at autopsy. These included 7 with space-occupying or tumour-like lesions, namely one with multiple cysts, three with haemangiomas, a lobated liver with multiple nodules of focal nodular hyperplasia, one with a metastasis which also had a small haemangioma and one with a hepatocellular carcinoma. Fine particle barium diluted 2:1 with water was injected by hand to fill the arterial system. In the lobated liver, the portal system was also filled. High definition radiographs of liver slices showed arteriographic detail not visible on angiography. The arteriographic appearances were correlated with the macroscopic and microscopic pathology. Liver cysts compress the arteries and arterioles but an apparent halo on the whole liver radiograph was shown to be spurious on a 1 cm thick high definition film. The small vessel pattern of haemangiomas is well demonstrated accounting for the hyperechoic sonograms but hypoechoic areas may also occur due to involution of or haemorrhage into tumours. The small lesions of focal nodular hyperplasia had a poor arterial supply but filled from a portal venous injection. Metastases had a peripheral network of small vessels, central necrosis and normal sized peripheral arteries with no large artery entering the tumour. In hepatocellular carcinoma, a large artery was demonstrated entering the tumour which was considerably more vascular than the metastases. These features should aid in distinguishing these lesions on sonography.

Autopsy↗
PubMed1991

Asymptomatic cerebral calcification--a previously unrecognized feature.

While investigating the radiological appearances of globus pallidus calcification in an autopsy case, cortical-pia mater calcification was detected. There was no documentation of its existence in the literature of radiology, neurology and neuropathology. To establish its incidence and clinical significance, 20 consecutive autopsy brains (15 males, 5 females, age 32-73 years, mean age 56.7) were studied with high resolution radiography and histology. Clinical records, autopsy findings, in-life plain skull films and computed tomography of the brain (if available) were reviewed. Radiologically, the calcifications appeared as 1-2 mm irregular spots or tiny pin-point opacities in the pia mater and subcortical regions, either unilaterally or bilaterally in the frontal (15 cases), temporal (15), parietal (3) and occipital lobes (1). Similar calcification was detected in 1 of the 3 in-life computed tomographic scans available. Histologically, these cortical-pia mater calcifications were extracellular amorphous calcified masses of various sizes in necrotic neural tissue, frequently associated with microscopic haemorrhage and hypoxic neuronal changes in the adjacent brain tissue. Blood vessels in the region were not hyalinized or calcified. The occurrence was not related to age. Hospital stay was less than 7 days in 14 and less than 30 days in 2; 50% of patients died within 48 hours after admission. None of the patients had records of long term cytotoxic chemotherapy, radiotherapy or central nervous system infection. Two had stroke, one had cerebellar atrophy and one mild hypercalcaemia. The high incidence of calcifications in the temporal lobes, while asymptomatic, suggests that cortical calcification may be a pointer to the aetiology of idiopathic epilepsies in the elderly.

Adult↗
PubMed1991

Computed tomography contrast enhancement of cervical lymphadenopathy.

In a prospective study of 51 cases of lymphadenopathy (44 with cervical metastatic nasopharyngeal carcinoma, NPC) using intravenous contrast and computed tomography (CT), a ring enhancement was observed. A retrospective review of 105 cervical carcinomatous lymph nodes (64 with metastatic NPC) showed a prominent peripheral hypervascular pattern not seen in 48 lymphomas and 60 normal controls. We conclude that in carcinomatous cervical lymphadenopathy, enhancement can be achieved by intravenous contrast and CT; and the peripheral hypervascularity is the anatomical basis for the ring appearances seen radiographically.

Adult↗
PubMed1990

Demonstration of Lipiodol in paraffin sections using a modified silver impregnation technique.

To demonstrate postangiographic Lipiodol (LIP) in hepatocellular carcinoma (HCC) in paraffin sections, direct impregnation of formalin-fixed tissue blocks with silver nitrate (AgNO3) was followed by routine processing. LIP appeared as black globules in the sinusoids. Ninety-four tissue blocks from 13 postangiographic LIP HCCs and 69 from 8 non-LIP HCCs and 4 fatty livers were studied. Seventy-two of 73 negative controls and all positive blocks as seen on soft tissue radiographs (STRs) were correctly coded (specificity 98.6%, sensitivity 100%). Twenty-six of the 44 LIP-negative areas on STRs from LIP cases contained scanty globules of less than 10 microns in diameter. Fatty change gave no positive readings. Thus, modified AgNO3 impregnation is a simple, accurate means of detecting LIP in high-quality paraffin sections suitable for tumor diagnosis and, if applied to postangiographic LIP, ultrasonographically guided liver biopsy, can verify that a biopsy has reached a suspected tumor focus.

Biopsy↗