Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since 1983, many papers tell of the usefulness of isoflurane for induced hypotension. It can induce and maintain stable arterial hypotension during neurosurgery, or any other surgical procedure requiring induced hypotension. Its use has proved to be simple. Although other hypotensive techniques are possible, especially if only moderate hypotension is required, the mechanism of action of isoflurane is very appealing: it reduces arterial pressure by reducing the peripheral resistances, without reducing the output, unlike halothane or trinitrin. Moreover, as it is anaesthetic, it reduces the overall oxygen consumption, such that if there were a fall in output one could assume that it was related to the level of oxygen consumption. When there is no severe hypocapnia, isoflurane, quite unlike sodium nitroprusside, lowers cerebral oxygen consumption without affecting cerebral blood flow rate. It does however increase intracranial pressure, like all the other hypotensive agents used. It does not increase filling pressures and has no effect on blood gas movements, unlike sodium nitroprusside and trinitrin which increase filling pressures and the intrapulmonary shunt. It is not toxic either, unlike sodium nitroprusside. The expensiveness of the drug is balanced by its many advantages, all the more so as this cost can be reduced by using a filter-system for some cases (e.g. middle ear surgery), or by using some drug combinations which need yet to be defined. However, there exist some disadvantages which may, in fact, be due to experimental conditions: failure of induced hypotension, coronary ischaemia, doubtful cerebral protection in case of focal areas of ischemia, different degrees of organ vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:[Can isoflurane be advised for controlled hypotension?]. 306 28

The paper contains the results of light microscopical, electron microscopical and histochemical examinations of chronic otitis media, with and without cholesteatoma, with special focus on the problems regarding bone resorption. It is demonstrated that bone resorption takes place without the presence of cholesteatoma itself, even though the magnitude of resorption is higher in the cases with cholesteatoma. It is demonstrated that there is always a layer of subepithelial granulation tissue between the cholesteatoma membrane and the underlying bone. The picture in the resorbing zone is dominated by mononuclear histiocyte like cells, containing dense cytoplasmatic bodies, called lysosomes, and it is demonstrated that the marker enzyme for acid hydrolases, the acid phosphatase, is present in large quantities, both in the histiocytes, as well as spread along the bony surface. It is concluded that a possible mechanism for bone resorption is performed by the acid hydrolases, contained in the histiocytes, working at acid pH. It is noteworthy that the multinucleated osteoclast is not demonstrated in the resorbing margin of bone and that the picture is dominated by capillary proliferation, indicating that ischemia does not play a role in bone resorption. On the contrary, this is in the author's opinion caused by inflammation and hyperemia. The various factors influencing bone resorption in general and in chronic otitis media are discussed and a new model for studying cholesteatoma pathology in the middle ear is presented.
 ...
PMID:Bone resorption in chronic otitis media. The role of cholesteatoma, a must or an adjunct? 726 54

The purpose of the study was to evaluate the effect of delta-9-tetrahydrocannabinol (THC), the major psychoactive constituent of marijuana, on ischemic neuronal injury. A 12-min ischemic insult was induced by a reduction in systolic blood pressure to a mean of 50 mm Hg, followed by bilateral carotid artery occlusion at a middle ear temperature of 37.5 degrees C. THC at either a low (0.1 mg/kg; n=8) or high (10 mg/kg; n=8) dose was injected i.p. every 12 h for 7 days prior to ischemia. Non-treated ischemic (n=8) animals formed the control group. The animals were sacrificed 3 weeks post-ischemia for quantitative histopathology. THC at either dose did not significantly reduce ischemic neuronal damage in the hippocampus. The high dose THC-treated group showed significantly less neocortical injury, compared to either the control or low-dose THC groups (p<0.05). The striatum was markedly protected by both low and high dose THC (p<0.001). This regionally specific protection implies that either the hippocampus undergoes suprathreshold ischemic injury or that mechanisms of ischemic injury vary in different brain regions.
 ...
PMID:The effect of delta-9-tetrahydrocannabinol on forebrain ischemia in rat. 1070 May 66

The incidence of sensorineural hearing loss often caused by direct damage to the cochlear hair cells is by far more frequent and more serious than disorders affecting the external ear or the middle ear. Mechanisms that are discussed to be relevant for the genesis of tinnitus and acquired hearing impairment are hair cell loss, signal transduction disturbances in the region of the outer and inner hair cells and the spiral ganglion, impairment of cochlear blood flow, mechanical disturbance, and hypoxia and ischemia. The present model surveys the possible cellular and molecular biological causes of peripherally developing hearing loss and tinnitus. In particular, the paper discusses the roles of hypoxia and ischemia in the cochlea and in the etiology of the neurosensory types of tinnitus. Peripheral origins of hearing disturbances and tinnitus may be: (a) damage to the stereocilia and the tip links, (b) dysfunction of potassium channels or (c) modification of the glutamate release. Moreover, the hypoxia inducible factor-1 may have an important role to play as a key transcription factor in the cells' adaptation to hypoxia and ischemia. An impairment of the cochlear blood flow may be induced by the expression of target genes like nitrogen monoxide synthase and endothelin-1 resulting in tinnitus. The paper discusses consequences resulting from the present model for the medical treatment of peripherally developing tinnitus and hearing loss.
 ...
PMID:A model of peripherally developing hearing loss and tinnitus based on the role of hypoxia and ischemia. 1675 23

The chorda tympani (CT) is important in gustatory sensation from the anterior two-thirds of the tongue and in secretomotor innervation to the submandibular and sublingual glands. Although the blood supply to the CT is not well delineated in the literature, some studies have shown that a posterior tympanic branch of the stylomastoid artery supplies CT at its origin from the mastoid segment of the facial nerve. We review the blood supply to the CT comprehensively. A better understanding of the vasculature involved is required to prevent iatrogenic injury during middle ear surgery and complications secondary to ischemia.
 ...
PMID:Blood supply to the chorda tympani: A review and clinical applications. 3259 40