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Biomedical subjects

M D Cohen

Publications and source records attributed to M D Cohen.

At least 55 records · Page 3Linked to original sources
PubMed1996

Pulmonary immunotoxicity of inhaled ammonium metavanadate in Fisher 344 rats.

Male Fisher 344 rats were exposed to 2 mg vanadium(V)/m3 (as ammonium metavanadate NH4VO3, 0.32 micron MMD) atmospheres for 8 hr/day for 4 days in a nose-only exposure system. In exposed rats, lung V burdens increased in a time-dependent fashion. Analysis of lung cells and lavage fluid 24 hr after the final exposure suggested that tissue damage and a strong inflammatory response was elicited; numbers of neutrophil and small macrophages (Mø), as well as levels of lavageable protein and lactate dehydrogenase, were significantly elevated as compared with levels observed with air-exposed rats. Vanadium also affected pulmonary alveolar Mø (PAM) capacities to produce and respond to immunoregulating cytokines. Inducible PAM production of tumor necrosis factor-alpha was significantly inhibited, as was the ability to increase cell surface Class II/I-A molecule expression in response to interferon-gamma (IFN gamma). PAM from V-exposed hosts were also inhibited in their ability to be primed by IFN gamma to produce superoxide anion and hydrogen peroxide in response to stimulation with opsonized zymosan. These studies indicate that short-term repeated exposure of rats to atmospheric V, at levels encountered in an occupational setting, can alter host pulmonary immunomocompetence, with one major effect occurring at the level of cytokine-related functions. These alterations may be underlying mechanisms for the well-documented increases in bronchopulmonary infections and cancers in workers chronically exposed to V-containing atmospheres.

Administration, Inhalation↗
PubMed1996

Vanadium affects macrophage interferon-gamma-binding and -inducible responses.

Mouse WEHI-3 cells were exposed overnight to vanadium [V; ammonium metavanadate (NH4VO3) or vanadium pentoxide (V2O5)] to determine whether documented V-induced immunomodulation might arise from altered macrophage (M phi) interactions with interferon-gamma (IFN gamma) or altered IFN gamma-inducible responses. Binding studies performed at 22 degrees C indicated that although NH4VO3-pretreated cells had approximately 48% fewer actively-binding Class I IFN gamma receptors, binding affinities were 1.5-fold greater than that of control cell receptors; Class II expression was unaffected but affinities were reduced 2-fold. Postbinding IFN gamma-receptor complex internalization was unaffected by V pretreatment. Spontaneous production of both hydrogen peroxide and superoxide anion was significantly increased by treatment with both V compounds. Total hydrogen peroxide and superoxide production was increased by stimulation of IFN gamma-primed cells with zymosan, but relative increases in primed V-treated cells were lower than that in controls. Vanadium-treated cells also displayed decreased rates of IFN gamma-induced changes in [Ca2+]i levels secondary to increased resting [Ca2+]i levels. Although V-treated cells did not display significant increases in I-A expression after IFN gamma treatment, increased numbers of I-A+ cells (irrespective of priming) and lower maximal antigen densities than observed on I-A+ control cells were evident. Results from this study show that V exposure may produce alterations in M phi-mediated functions, in part, by modifying cell interactions with IFN gamma and subsequent IFN gamma-dependent functional parameters.

Animals↗
PubMed1996

Growth of the solitary kidney after nephrectomy in children with unilateral Wilms' tumor.

OBJECTIVE: We reviewed the length of the solitary kidney from all ultrasound examinations in 34 children who had undergone unilateral nephrectomy for Wilms' tumor, in order to determine the frequency of renal hypertrophy in this population. Standard sonographic criteria for nephromegaly were used. MATERIALS AND METHODS: We generated a z-score for each measurement of the renal length, using an interpolated computer model based on published standards for sonographic renal length in relation to age. A retrospective age- and gender-matched control population of children with sonographically normal paired kidneys was generated from a departmental computerized pediatric uroradiology data base, and their ipsilateral renal lengths were compared with those of the study patients. Sonographic renal hypertrophy (SRH) was defined by two or more consecutive measurements of the renal length exceeding two standard deviations longer than the mean for the patient's age, with no later normal measurement. RESULTS: Seventeen (50 %) of the 34 patients developed SRH. The latest measurements of the solitary kidney in the patients were significantly longer (mean z = 2.210) than in their controls (mean z = 0.040), even among the patients who did not develop SRH (patients' mean z = 1.000, controls' mean z = -0. 210, p < 0.001). Because boys had slightly longer kidneys than girls (both patients and controls), SRH was also noted more often in boys. The frequency of SRH was unrelated to age at nephrectomy, side of the solitary kidney, tumor stage, chemotherapy regimen, or treatment with radiation therapy. CONCLUSIONS: Although renal growth in a solitary kidney is accelerated in most children after unilateral nephrectomy for Wilms' tumor, the sonographic length of the solitary kidney will be larger than normal in only half of the patients.

Adolescent↗
PubMed1996

Normal appearance and size of the diaphragmatic crura in children: CT evaluation.

PURPOSE: The objectives of the study were to document the normal CT appearance and size of the crura of the diaphragm in children. MATERIALS AND METHODS: The CT scans of 80 children (0-15 years) were reviewed. The children were divided into eight age groups. The maximal transverse diameters of the right and left crura were measured. They were normalized by comparison with the transverse and anterior-posterior diameters of the 12th thoracic vertebra (T12) and the transverse abdominal diameter at T12. The crura were also evaluated as to whether their contour was smooth or nodular. RESULTS: The diaphragmatic crura of smaller children appear large, relative to body size and the diameters of the T12 vertebral body, compared with those in older children. Crural width does not increase significantly with age. Additionally, the crura were found to have a greater tendency to be nodular in appearance in children under the age of 5 years than in older children. CONCLUSION: Diaphragmatic crura are more nodular and larger relative to body size in younger children.

Abdomen↗
PubMed1996

Applications of magnetization transfer contrast in the musculoskeletal system in children.

Magnetization transfer (MT) is a new MR imaging technique which has the potential to create contrast differences between normal and pathologic tissues distinct from T1- and T2-weighted contrast. The technique has been used in adults but received little consideration for pediatric imaging. This article reports the successful creation of MT contrast between normal and abnormal tissues in seven children.

Adolescent↗
PubMed1996

Visual presentation of the staging of pediatric solid tumors.

Staging systems are used in staging most pediatric solid tumors outside the central nervous system. Common solid, nonneurologic pediatric tumors include liver tumors, Hodgkin disease, non-Hodgkin lymphoma, Wilms tumor, rhabdomyosarcoma, neuroblastoma, Ewing sarcoma, and osteosarcoma. Traditional staging of pediatric tumors depends on the anatomic distribution of the malignant disease. Almost all staging systems are based on the spread of the local primary tumor, metastasis to regional lymph nodes, and distant blood-borne metastatic spread. There is some variability as to how tumor spread is assessed. Such assessment may be performed before or after surgery. There are many potential problems with tumor staging systems. The systems vary in complexity and clinical usefulness, and there is some variation in the criteria used in the different systems. It is important for radiologists to have a sound working knowledge of staging systems to facilitate accurate staging. Imaging is an important aspect of every staging system.

Bone Neoplasms↗
PubMed1996

Imaging of gastrointestinal malignancy in childhood.

Gastrointestinal malignancies in children are a rare and diverse group of neoplasms. Presenting signs and symptoms are nonspecific, but age at presentation and the presence of an elevated serum alpha-fetoprotein can provide helpful clues in tailoring a differential diagnosis. The role of imaging is to localize and characterize the tumor and define resectability. Plain films, ultrasound, and CT scans are the primary modalities employed, with MR imaging utilized in equivocal cases.

Adolescent↗
PubMed1995

Reforming Georgia's mental health system.

Legislation passed in 1993 makes sweeping administrative structural changes in Georgia's mental health system. Underlying these changes is the core value that consumers and families should be empowered to participate in the design, contracting, and evaluation of services. The key structural component is the creation of regional boards, comprised of at least 50% consumers and family members, which have the capacity to plan and contract for services and to evaluate the outcomes of those services. This paper describes Georgia's mental health system before these changes, the development of the initiative for reform, the process and problems associated with the passage of the legislation, and the current status of the implementation of the legislation.

Community Mental Health Services↗
PubMed1995

Hematologic malignancies and the use of methotrexate in rheumatoid arthritis: a retrospective study.

PURPOSE: To evaluate the relationship between use of methotrexate in rheumatoid arthritis patients and development of hematologic malignancies. PATIENTS AND METHODS: We retrospectively analyzed all patients registered at the Mayo Clinic from 1976 through 1992 with rheumatoid arthritis (n = 16,263) cross-indexed with patients registered during the same period with a hematologic malignancy (n = 21,270). Adult patients were selected who had rheumatoid arthritis, were treated with a disease-modifying antirheumatic drug, and subsequently developed a hematologic malignancy. RESULTS: Thirty-nine patients met the selection criteria. Twelve of them had been given methotrexate. The characteristics of those who received methotrexate, including the type of hematologic malignancy, did not differ from those of patients who received other disease-modifying antirheumatic drugs. CONCLUSIONS: Hematologic malignancies are uncommon in patients with rheumatoid arthritis treated with disease-modifying antirheumatic drugs, including methotrexate. There does not appear to be a relationship between the peak or cumulative dose or the duration of methotrexate therapy and the subsequent development of hematologic malignancy. The histologic types of hematologic malignancy seen in the methotrexate-treated patients did not differ from those of patients treated with other disease-modifying antirheumatic drugs.

Adult↗
PubMed1995

Volume detection threshold: quantitative comparison of computed radiography and screen-film radiography in detection of pneumothoraces in an animal model that simulates the neonate.

PURPOSE: To quantitatively compare computed radiography (CR) and screen-film radiography (SFR) in the detection of pneumothorax in an animal model that simulates the neonate. MATERIALS AND METHODS: Three rabbits underwent placement of 5-F catheters in the right pleural space. Eight CR and eight SFR images were obtained. Volume-controlled pneumothorax was induced by incrementally injecting 4 cm3 of air (24 cm3 total) and four CR and four SFR images were obtained after each injection. Four radiologists blindly viewed the images twice (eight readings per image, 1,600 total observations). A dichotomous yes-no score for the presence of pneumothorax was used to calculate the volume detection threshold (VDT), defined as the air volume at which 50% of the pneumothoraces can be detected. The authors plotted the likelihood of a pneumothorax against the air volume by using the confidence indicator. RESULTS: Intraobserver VDT values for CR and SFR were not significantly different. CONCLUSION: CR is as accurate as SFR in the detection of pneumothorax in this quantitative animal model.

Animals↗
PubMed1994

Immunotoxicity of sulfuric acid aerosol: effects on pulmonary macrophage effector and functional activities critical for maintaining host resistance against infectious diseases.

Despite the widespread occurrence of acidic sulfur oxides in the ambient environment and their potential risks to human health, effects associated with pulmonary immune defenses have been poorly studied. The current in vivo study was designed to provide some insight into this relatively unexplored area by investigating the impact of inhaled sulfuric acid on immune defense mechanisms critical for maintaining pulmonary resistance against infectious diseases. Results of this study demonstrate that repeated inhalation of sulfuric acid reduces the uptake and intracellular killing of pathogenic bacteria by exposed pulmonary macrophages, and depresses the activity/production of important biological modifiers critical for maintaining pulmonary immunocompetence. These findings have important implications for human health, and may contribute to a better understanding of the possible mechanism(s) underlying the epidemiological evidence which suggests an association between total sulfates in the ambient air and increased incidence of acute bronchitis and lower respiratory illness in school-age children.

Aerosols↗
PubMed1994

The effect of divalent nickel (Ni2+) on in vitro DNA replication by DNA polymerase alpha.

The effects of the carcinogenic metal nickel on DNA polymerase alpha (pol alpha) activity and fidelity have been analyzed. In the absence of Mg2+, the presence of Ni2+ ions at concentrations below 0.25 mM gave rise to a dose-dependent activation of pol alpha as monitored by [3H]dTMP incorporation into an activated DNA template. The apparent Km for Ni(2+)-dependent pol alpha incorporation of dTTP was estimated to be 25 microM, which was about 10 times higher than the Km for Mg2+ (2.3 microM). Above 0.25 mM, Ni2+ caused a dose-dependent inhibition of pol alpha activity and the Ki was calculated to be 1.5 mM. Scatchard analyses showed that Ni2+ binds to affinity-purified pol alpha and associated proteins at two tight binding sites with a Kd of approximately 50 microM and at eight weak binding sites with a Kd of approximately 4 mM. In the presence of 2 mM Mg2+, the addition of Ni2+ to the reactions caused an inhibition of polymerase activity. The inhibition patterns tended to switch from competitive to mixed-type to noncompetitive as a function of Ni2+ concentration. Lastly, Ni2+ increased the incorporation of the modified nucleotide dideoxy-CMP in reactions using varying ratios of dideoxy-CTP/dCTP.

Cytidine Triphosphate↗
PubMed1994

The radiographic anatomy of the thoracic pedicle.

A cadaveric study of the radiographic characteristics of the thoracic pedicle was performed. Dried vertebrae at T6 and T7 were mounted and x-rayed at varying angles. The relationship of the pedicles to wire markers, methyl methacrylate cores, and Cotrel Dubousset hooks was analyzed. The oval image of the pedicle on radiographs is its waist. This image narrows with axial rotation of the x-ray beam. The relationship of a correctly placed pedicle hook to its pedicle is radiographically unchanged by rotation. Conversely, an incorrectly placed hook cannot be made to appear in position by rotating the x-ray beam.

Adult↗
PubMed1994

Osteomyelitis and pyogenic infection of the sacroiliac joint. MRI findings and review.

Acute pyogenic sacroiliac joint infection and osteomyelitis of adjacent bones often present with severe, poorly localized lower back, pelvic or hip pain. Five cases of sacroiliac joint infection or sacroiliac bone osteomyelitis were evaluated by MRI. MRI may be a helpful diagnostic tool to evaluate early changes of infection in the sacroiliac area. It is very sensitive for detecting bone marrow abnormalities; however, it is non-specific and can not accurately differentiate osteomyelitis from sacroiliitis.

Arthritis, Infectious↗
PubMed1994

Cystic angiomatosis of bone: MR findings.

Cystic angiomatosis of bone is a rare disorder characterized by widespread lytic bone lesions with or without associated soft tissue or visceral lymphangiomatosis. The disorder is often initially incorrectly diagnosed as Langerhans cell histiocytosis. Unfortunately, biopsy of long bone lesions will often yield only fluid, thereby making a histologic diagnosis difficult. This report describes the MR findings in a patient with cystic angiomatosis of bone. We believe that the MR findings are highly suggestive of the correct diagnosis and that MR should eliminate the need for excisional biopsy in future cases.

Angiomatosis↗
PubMed1994

Ruptured cystic mesenchymal hamartoma: an unusual cause of neonatal ascites.

Cystic mesenchymal hamartoma is an uncommon benign liver neoplasm usually seen in infants with an asymptomatic abdominal mass [1]. We report a neonate who presented with a ruptured cystic mesenchymal hamartoma which produced respiratory distress due to massive ascites. To our knowledge, this complication has never been reported.

Adolescent↗
PubMed1994

Langerhans cell histiocytosis of bone: MR imaging.

Magnetic resonance (MR) images of 12 pathologically proven lesions of Langerhans cell histiocytosis (LCH) of bone were reviewed retrospectively. MR identified all lesions, three of which were not identified on plain radiographs. In all cases, MR showed greater abnormality than did plain radiographs. With one exception, all lesions were hypointense on T1-weighted images and hyperintense on T2-weighted images. The lesions and associated soft tissue abnormalities were very conspicuous on short TI inversion sequences and T1-weighted post-contrast images. Follow-up MR studies in two patients after chemotherapy showed decreased size and enhancement of lesions compared with baseline studies.

Adolescent↗