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Biomedical subjects

L Mark

Publications and source records attributed to L Mark.

29 records · Page 2Linked to original sources
PubMed1985

Magnetic resonance imaging of the cavernous sinus.

The magnetic resonance (MR) appearance of the cavernous sinus was studied by correlating the MR images of normal volunteers and cryomicrotomic sections from six cadavers. In addition, MR images of patients with parasellar masses were compared with corresponding intravenously enhanced computed tomographic (CT) scans. The MR appearance of the cranial nerves in the cavernous sinuses is demonstrated, as well as MR signs of a parasellar mass, including obliteration of intracavernous venous spaces, displacement of the intracavernous internal carotid artery, and bulging of the lateral wall of the cavernous sinus. MR proved to be more effective than CT in delineating the parts of the cavernous sinus.

Aneurysm↗
PubMed1984

The pituitary fossa: a correlative anatomic and MR study.

This study characterizes the normal appearance of the pituitary fossa in partial saturation magnetic resonance (MR) images. In sagittal images, the pituitary fossa appears inhomogeneous. Correlation of sagittal MR images in normal subjects with sagittal cryomicrotomic images in cadavers suggests that the highest intensity signal from the posterior-inferior pituitary fossa is due to a fat pad. This conclusion was supported by MR images and postmortem cryotome sections obtained in normal subhuman primates. The cause of the less constant, low intensity signal was less certain. The height of the pituitary gland in sagittal images was usually less than 8 mm, and the upper surface was flat or concave.

Adipose Tissue↗
PubMed1976

Clinical and morphologic features of hepatic angiosarcoma in vinyl chloride workers.

Fifteen male workers exposed to vinyl chloride developed angiosarcoma of the liver. Thirteen died of disease and two are currently living for short periods after diagnosis. Their ages ranged from 36 to 58 years (average 47.5 years). Their exposure time ranged from 4 to 27.8 years (average 16.9 years). The most common presenting symptoms were fatigue, weight loss, and abdominal pain. Hepatomegaly followed by splenomegaly were the most common physical findings. Biochemical profiles yielded variable results and proved to be of little value in the detection or diagnosis. Of eight patients autopsied, distant organ involvement was present in two cases, duodenal involvement in one, and direct extension of tumor to adjacent organs or tissues in four additional ones. The remainder, diagnosed by open liver biopsy, revealed no tumor extension. The gross features of the tumors were hemorrhagic necrosis, cystic degeneration, fibrosis, and apparent multicentricity. The histologic features were those of the typical angiosarcoma found in a variety of sites with a wide range of cellular differentiation. The histologic diagnosis was often impaired by the extensive tumor necrosis. Elsewhere in the liver subcapsular fibrosis, a distinct type of portal fibrosis, and endothelial cell hyperplasia with or without sinusoidal dilatation were noted. The reduction of industrial chemical exposure has already been achieved and will hopefully eliminate this chemically related tumor in the future. There is, however, a significant group of previously exposed workers who will require careful monitoring to detect functional abnormalities of the liver and possible early neoplastic changes.

Adult↗
PubMedDate not supplied

The impact of a helicopter emergency medical services program on potential morbidity and mortality.

INTRODUCTION: The evaluation of the effectiveness of helicopter emergency medical services is currently a major focus of air transport research, and dispatch judgment likely will play a significant role in any research aimed at measuring outcome or impact. SETTING: Two rotor-wing programs in Alberta, Canada. METHODS: A panel of experts evaluated the effectiveness of a helicopter service in Canada. Four hundred sequential patient records were examined and categorized into four risk levels. Level 1 included patients who required critical intervention. Level 2 included patients in whom a major deterioration of vital signs could be expected. Level 3 patients were those for whom transport by an advanced life support ground unit would have been adequate. Level 4 was strictly for missions in which patient transport by any other means would have been impractical, such as remote locations (these cases were double-rated). RESULTS: Risk level 1 included 98 cases (24.5%); risk level 2, 266 cases (66.5%); risk level 3, 36 cases (9%); and risk level 4, 16 cases, two of which were rated level 1, 11 rated level 2, and three rated level 3. CONCLUSION: The results indicate that in 91% of the reviewed cases, helicopter transport was appropriate, representing a reasonable and judicious use of a helicopter emergency medical service.

Air Ambulances↗
PubMedDate not supplied

Calcium-dependent degradation of surfactant protein A by activated neutrophils due to serine proteases.

The effects of activated leukocytes on surfactant function and composition were examined to better define the mechanisms by which acute inflammation contributes to respiratory distress syndrome (ARDS). Peripheral blood leukocytes from healthy volunteers were incubated in vitro with surfactant for 4 hours: (1) in the absence of activation; (2) following activation by addition of phorbol myristate acetate (PMA); (3) following addition of PMA + FeCl2/EDTA; (4) PMA + FeCl2; (5) PMA + EDTA; (6) PMA + FeCl2 + superoxide dismutase (SOD) + catalase; (7) PMA + EDTA + serine or cysteine protease inhibitors. Surfactant was then repurified by sucrose gradient centrifugation, and function, phospholipid and protein composition, and extent of lipid peroxidation were assessed. PMA caused activation of leukocytes as detected by dichlorofluorescene assay. Lipid peroxidation (assessed by conjugated diene assay) was detected in all samples containing PMA. Abnormal function was noted in surfactant exposed to activated cells with 1 mM EDTA, whereas activation alone, or with FeCl2, had no effect. SOD + catalase prevented lipid peroxidation, but did not prevent leukocyte-mediated dysfunction, which was associated with a marked reduction in surfactant protein A (SP-A), but no detectable change in surfactant protein B (SP-B) or phospholipid composition. Serine protease inhibitors prevented SP-A degradation and dysfunction, whereas cysteine protease inhibitors had no protective effect. Addition of purified SP-A (5% w/w) to dysfunctional surfactant restored normal function, while SP-B/C mixture (3%) did not. Activated leukocytes cause surfactant dysfunction in vitro by serine protease-mediated degradation of SP-A, which occurs only in the presence of EDTA, and is prevented by addition of calcium. Although lipid peroxidation mediated by leukocyte release of free-radical products was also detected, surfactant dysfunction appears to be unrelated to this process.

Albumins↗
PubMedDate not supplied

The temporal bone.

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Animals↗