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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Blood flow rate in a vascular network is proportional to the pressure difference between the arterial and venous sides and inversely proportional to the viscous and geometric resistances. Despite rapid progress in recent years, there is a paucity of quantitative data on these three determinants of blood flow in tumors and several questions remain unanswered. This paper reviews our current knowledge of these three parameters for normal and neoplastic tissues, the methods of their measurements, and the implications of the results in the growth and metastasis formation as well as in the detection and treatment of tumors. Microvascular pressures in the arterial side are nearly equal in tumor and nontumorous vessels. Pressures in venular vessels, which are numerically dominant in tumors, are significantly lower in a tumor than those in a nontumorous tissue. Decreased intravascular pressure and increased interstitial pressure in tumors are partly responsible for the vessel collapse as well as the flow stasis and reversal in tumors. The apparent viscosity (viscous resistance) of blood is governed by the viscosity of plasma and the number, size, and rigidity of blood cells. Plasma viscosity can be increased by adding certain solutes. The concentration of cells can be increased by adding cells to blood or by reducing plasma volume. The rigidity of RBC, which are numerically dominant in blood, can be increased by lowering pH, elevating temperature, increasing extracellular glucose concentration, or making the suspending medium hypo- or hypertonic. Effective size of blood cells can be increased by forming RBC aggregates (also referred to as rouleaux). RBC aggregation can be facilitated by lowering the shear rate (i.e., decreasing velocity gradients) or by adding macromolecules (e.g., fibrinogen, globulins, dextrans). Since cancer cells and WBC are significantly more rigid than RBC, their presence in a vessel may also increase blood viscosity and may even cause transient stasis. Finally, due to the relatively large diameters of tumor microvessels the Fahraeus effect (i.e., reduction in hematocrit in small vessels) and the Fahraeus-Lindqvist effect (i.e., reduction in blood viscosity in small vessels) may be less pronounced in tumors than in normal tissues. Geometric resistance for a network of vessels is a complex function of the vascular morphology, i.e., the number of vessels of various types, their branching pattern, and their length and diameter. Geometric resistance to flow in a single vessel is proportional to the vessel length and inversely proportional to vessel diameter to the fourth power.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Determinants of tumor blood flow: a review. 328 47

Nd-YAG laser resection of a completely obstructing right mainstem tumor in a 36-year-old man was complicated by right lung hyperinflation and left lung collapse and accompanying ventilatory failure. This was attributed to obstruction of the right mainstem bronchus during exhalation, but not inhalation, in a patent but irregularly shaped bronchus postresection. Intubation, positive pressure breathing, bronchodilator therapy, and laser excision of residual right mainstem tumor resolved the ventilatory failure.
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PMID:Pulmonary hyperinflation following Nd-YAG laser resection of an obstructing mainstem tumor. 328 50

The ability of magnetic resonance imaging (MRI) to detect T-factor was compared with that of computed tomography (CT) in 52 patients with primary lung cancer proven by surgery or autopsy, and the results were analyzed in relation to the operative and pathologic findings. In the diagnosis of tumor invasion of the heart and great vessels, MRI provided information as accurate as CT. The T1-weighted images in particular were of considerable value in separating the tumor from the mediastinal and hilar fat. Tumor extent in accompanying peripheral obstructive pneumonia or collapse was demarcated in 21% of the cases studied by CT and in 33% to 53% by MRI. On the other hand, the T2-weighted images obtained with longer echo time (TE) were useful in distinguishing the tumor from secondary changes.
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PMID:Detection of T-factor in lung cancer using magnetic resonance imaging and computed tomography. 336 28

On the basis of comprehensive clinicopathological evidence 6 patients presenting with unilateral left-sided hyperlucent lungs are evaluated for pathogenesis, function and postoperative (n = 5) course. The common denominator in all proves to be moderate to severe hypoperfusion and overinflation of the respective lungs. Pulmonary function is characterized by a combined restrictive-obstructive pattern. In 4 patients overinflation is due to a central check-valve mechanism (tumor: n = 3; central airways collapse: n = 1), whereas in 2 increased translucency results from some sort of peripheral obstruction (Swyer-James syndrome: n = 1; congenital cystic bronchiectasis: n = 1). We consider the origin of hypoperfusion to be alveolar distension and hypoxic precapillary vasoconstriction, both participating in diminished blood flow to the check-valve obstructed lung. In Swyer-James syndrome reduced vascularity is an additional feature. Preoperative and long-term postoperative lung function data of 5 pneumonectomized patients are compared. On the whole, FEV1 and IVC remain unchanged, whereas the obstructive profile (RV, RV/TLC, sRAW) improves. From these data it is concluded that the affected hyperlucent lung is 'amputated' even before operation - irrespective of the nature of tissue damage. On the other hand postoperative relief of airways obstruction is supposed to be due to both antiobstructive medication and the removal of a diseased lung.
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PMID:[The functionally amputated lung. Studies on the unilateral hyperlucent lung syndrome]. 339 39

The author recounts his experience over the past nine years, with the use of a large bone graft with an intact vascular pedicle taken from the iliac crest for the reconstruction of large defects in the proximal femoral region and for the solution of a number of difficult problems in which the femoral head is at risk of destruction or collapse. Some of these problems, particularly in the young patient, include large bony defects in the proximal femur after tumor resection, nonunion of the femoral neck fracture and avascular necrosis of the femoral head. The author cites a number of cases, comments on the satisfactory results that were obtained and cites the advantages of the large bone graft with an intact vascular pedicle.
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PMID:New method of hip reconstruction. 345 37

MRI and CT studies in 18 patients with proximal bronchogenic carcinoma and postobstructive lobar collapse were analyzed retrospectively. The relative abilities of these imaging techniques to identify central tumor by a contour abnormality and to distinguish tumor mass from collapsed lung by CT attenuation values and MRI signal intensities were compared. MRI and CT were equivalent in their ability to identify a contour abnormality, both succeeding in 13 of 18 (72%) patients. CT was more successful than MRI in differentiating tumor mass from collapsed lung. Dynamic computed tomography scanning differentiated tumor from collapsed lung in eight of ten (80%) patients. MRI demonstrated different signal intensities of tumor and collapsed lung in 8 of 18 (44%) patients. T2-weighted images more often separated tumor from collapsed lung than other imaging sequences.
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PMID:Differentiation of proximal bronchogenic carcinoma from postobstructive lobar collapse by magnetic resonance imaging. Comparison with computed tomography. 362 59

A 3-year-old horse presented with intermittent generalized seizures of 2-month duration. During interictal periods, the horse appeared normal and a cause for the seizures could not be identified. Necropsy revealed opacity of the leptomeninges, covering most of one cerebral hemisphere along with thinning and collapse of the cortex in the ipsilateral pyriform lobe. Histopathology demonstrated leptomeningeal vascular proliferation and meningothelial hyperplasia. Prominent tortuous vessels of the gyri and sulci extended into some regions of the subjacent cortex, where there was neuronal loss, ectopia, and disorganization. Clusters of prominent arterioles were found in the sclerotic choroid plexus of the lateral and fourth ventricles. Milder vascular lesions were present in the leptomeninges of the ventral brain stem, right cerebrum, spinal cord, and in the eye. The left trigeminal nerve was distorted by swollen fasicles containing onion bulb-like structures. Most bulbs contained central axons surrounded by myelin sheaths of variable thickness. Electron microscopy demonstrated concentrically arranged cells with continuous basal laminae and rare pinocytotic vesicles. S-100 immunohistochemistry showed strong positive staining in these cells. This is an unusual combination of lesions to which analogies can be drawn with the human neuroectodermal dysplasias, specifically Sturge-Weber disease. The relationship of the neuropathy to the leptomeningeal hemangiomatosis is unclear, but a compound anomaly in embryological development resulting in dysplasia and neoplasia may be involved.
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PMID:Meningocerebral hemangiomatosis resembling Sturge-Weber disease in a horse. 368 94

Thirteen cases of canine pheochromocytoma seen at the University of Minnesota Veterinary Teaching Hospital between 1981 and 1985 were reviewed. In 8 cases, the neoplasms were locally invasive; in the remaining cases, they were confined to the adrenal gland. Clinical signs compatible with fatal cardiovascular collapse secondary to a hypertensive or arrythmic episode were observed in 6 of 8 dogs with invasive neoplasms that died during examination or shortly thereafter. The remaining 2 dogs with invasive neoplasms had antemortem diagnoses of adrenal gland neoplasm with metastases and were euthanatized. Invasion or encroachment of the caudal vena cava in 6 dogs and encroachment of the aorta and other regional vasculature in 2 dogs were discovered at necropsy. In 5 dogs, the noninvasive pheochromocytoma was found incidentally during necropsy.
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PMID:Pheochromocytoma in dogs: 13 cases (1980-1985). 369 21

In patients with big, tumorous changes in the vertebral bodies, conservative measures like radiotherapy, medical therapy, and external support measures are often no longer applicable. As a result of the instability of the spinal column, most of the patients are bedridden and in great pain. Signs of root compression occur frequently, as do incipient or incomplete transverse lesions. On the one hand, these signs result from tumor growth and on the other from collapse of the vertebral bodies with kyphosis and fragment dislocation in the spinal canal. In these patients the procedure of choice is "ventral" tumor removal, decompression of the spinal cord and roots, followed by stabilization. By the "dorsal" operative method, it is not possible to overcome the major cause of the instability and pain. On the basis of the results obtained in 100 "ventral" resections of the vertebral bodies, the treatment strategy is presented, ranging from the preliminary examination to the postoperative period.
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PMID:[Treatment strategy of malignant bone tumors of the spine]. 369 19

In a 64-year-old male, recurrent syncope, hypotension and bradycardia developed repeatedly. The systolic blood pressure fell and could not be measured by auscultation method and the heart rate decreased to under 20 bpm. He recovered from unconsciousness in several minutes. No precipitating cause was apparent for such episodes. Physical examination revealed swollen lymph nodes in the upper cervical regions. Carotid sinus massage caused a fall of systolic blood pressure by 40 mmHg and the P-P interval lengthened to 1.96 sec. The otolaryngeal examination showed neoplasma in the pharynx. He received irradiation therapy on the primary lesion and the bilateral metastatic lesions. After irradiation (4,000 rad), the paroxysmal hypotension and bradycardia disappeared concomitantly with the reduction in size of the metastatic tumor. Hypersensitivity to carotid sinus massage, however, remained unchanged. In this case, the metastatic tumor around the carotid sinus seemed to be related to the syncope and the hemodynamic collapse.
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PMID:Recurrent paroxysmal hypotension and bradycardia in a patient with pharynx tumor metastasis to the cervical lymph nodes. 373 59


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