scholarly journals Role of L-DOPA in Spinal Nociceptive Reflex Activity: Higher Sensitivity of Aδ Versus C Fibre-Evoked Nociceptive Reflexes to L-DOPA

2011 ◽  
pp. 701-703
Author(s):  
E. D. SCHOMBURG ◽  
P. DIBAJ ◽  
H. STEFFENS
Keyword(s):  
Radiant Heat ◽  
Reflex Activity ◽  
Late Component ◽  
Early Component ◽  
Nociceptive Reflex ◽  
Reflex Pathways ◽  
Nociceptive Reflexes ◽  
C Fibre ◽  
Higher Sensitivity

The role of L-DOPA in spinal nociceptive reflex activity has been re-evaluated. In high spinal cats, with supraspinal loops being excluded, the onset of reflex facilitation induced by noxious radiant heat is delayed after injection of L-DOPA by 4 to 10 s, i.e. the early component of nociceptive reflex facilitation is blocked, while the late component persisted. Further investigations have shown that the early component of reflex facilitation induced by noxious radiant heat is mediated by Aδ-fibres and the late component by C-fibres. Therefore, it can be assumed that L-DOPA, like opioids, preferentially blocks the transmission in nociceptive reflex pathways from Aδ-fibres.

Direct Comparison of Heat-Evoked Activity of Nociceptive Neurons in the Dorsal Horn With the Hindpaw Withdrawal Reflex in the Rat

1998 ◽  
Vol 79 (1) ◽  
pp. 174-180 ◽  
Author(s):  
Michael M. Morgan
Keyword(s):  
Dorsal Horn ◽  
Receptive Fields ◽  
Radiant Heat ◽  
Field Size ◽  
Reflex Activity ◽  
Nociceptive Neurons ◽  
Withdrawal Reflex ◽  
Nociceptive Reflexes ◽  
Evoked Activity ◽  
Sole Criterion

Morgan, Michael M. Direct comparison of heat-evoked activity of nociceptive neurons in the dorsal horn with the hindpaw withdrawal reflex in the rat. J. Neurophysiol. 79: 174–180, 1998. Although the sensory coding of nociceptive neurons in the dorsal horn has been studied extensively, surprisingly little is known about how these neurons contribute to nociceptive reflexes. The objective of the present study was to examine the characteristics of dorsal horn neurons capable of initiating hindpaw withdrawal. To this end, neural and reflex activity were measured simultaneously in response to noxious radiant heat applied to the hindpaw in lightly anesthetized rats. Subsets of both multireceptive (MR; 52/95) and nociceptive-specific (NS; 19/46) neurons showed a consistent burst of activity that preceded the reflex. However, when compared with NS neurons, MR neurons as a group were: more likely to be active before the reflex (55 vs. 41%); more active before the reflex (31 vs. 23 Hz); and active earlier (2.8 vs. 2.3 s before the reflex). Subsets of MR neurons were active before the reflex regardless of receptive field size or location in the dorsal horn. In contrast, NS neurons with small receptive fields or those located outside of superficial laminae were rarely active before the reflex and thus unlikely to be part of the reflex circuit. These results suggest that current classification schemes, in particular MR and NS categories, cannot be used as the sole criterion to predict involvement in nociceptive reflexes. However, simultaneous measurement of neural and reflex activity provides an opportunity to determine the characteristics of nociceptive neurons involved in withdrawal reflexes.

scholarly journals Role of chloride channels in bradykinin-induced guinea pig airway vagal C-fibre activation

2005 ◽  
Vol 566 (1) ◽  
pp. 205-212 ◽  
Author(s):  
Min-Goo Lee ◽  
Donald W. MacGlashan ◽  
Bradley J. Undem
Keyword(s):  
Guinea Pig ◽  
Chloride Channels ◽  
C Fibre

scholarly journals SM22α Loss Contributes to Apoptosis of Vascular Smooth Muscle Cells via Macrophage-Derived circRasGEF1B

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Pin Lv ◽  
Ya-Juan Yin ◽  
Peng Kong ◽  
Li Cao ◽  
Hao Xi ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Vascular Smooth Muscle ◽  
Inflammatory Cell ◽  
Activated Macrophages ◽  
Abdominal Aortic ◽  
Specific Manner ◽  
Higher Sensitivity

Vascular smooth muscle cell (VSMC) apoptosis is a major defining feature of abdominal aortic aneurysm (AAA) and mainly caused by inflammatory cell infiltration. Smooth muscle (SM) 22α prevents AAA formation through suppressing NF-κB activation. However, the role of SM22α in VSMC apoptosis is controversial. Here, we identified that SM22α loss contributed to apoptosis of VSMCs via activation of macrophages. Firstly, deficiency of SM22α enhanced the interaction of VSMCs with macrophages. Macrophages were retained and activated by Sm22α-/- VSMCs via upregulating VCAM-1 expression. The ratio of apoptosis was increased by 1.62-fold in VSMCs treated with the conditional media (CM) from activated RAW264.7 cells, compared to that of the control CM ( P < 0.01 ), and apoptosis of Sm22α-/- VSMCs was higher than that of WT VSMCs ( P < 0.001 ). Next, circRasGEF1B from activated macrophages was delivered into VSMCs promoting ZFP36 expression via stabilization of ZFP36 mRNA. Importantly, circRasGEF1B, as a scaffold, guided ZFP36 to preferentially bind to and decay Bcl-2 mRNA in a sequence-specific manner and triggered apoptosis of VSMCs, especially in Sm22α-/- VSMCs. These findings reveal a novel mechanism by which the circRasGEF1B-ZFP36 axis mediates macrophage-induced VSMC apoptosis via decay of Bcl-2 mRNA, whereas Sm22α-/- VSMCs have a higher sensitivity to apoptosis.

Abstract T P354: The Role of Lindegaard Ratio on TCD for Predicting Angiographic Vasospasm Following Aneurysmal Subarachnoid Haemorrhage

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Aftab Ahmad ◽  
Khurshid Khan ◽  
Ghazala Basir ◽  
Carol Derksen ◽  
Ashfaq Shuaib ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Aneurysmal Subarachnoid Haemorrhage ◽  
Mean Flow ◽  
Anterior Circulation ◽  
University Of Alberta ◽  
Angiographic Vasospasm ◽  
Luminal Narrowing ◽  
Study Population ◽  
Higher Sensitivity

Background and objective: Middle cerebral artery (MCA) Lindegaard ratio (LR) has been used as indicator of moderate to severe vasospasm (VSP) following subarachnoid hemorrhage (SAH). However there have been many criticisms about the ability to detect impending vasospasm using Transcranial Doppler (TCD). The purpose of this study was to determine the correlation between TCD Mean Flow Velocities (MFV) and angiographic VSP after aneurysmal SAH using LR of several anterior circulation vessels. Methods: The study population included prospective collected data of 134 patients with aneurysmal SAH admitted to University of Alberta hospital from January 2006 to December 2008. Complete TCD was performed daily from day 2 to 14 from symptoms onset. All patients underwent cerebral angiography on admission and within 7 days following onset of symptoms. The M1, M2 MCA, ACA and intracranial ICA/ipsilateral extra cranial ICA velocity ratios (LR) were calculated and correlation was made with the presence of angiographic vasospasm (defined as more than one-third luminal narrowing). Then, anterior circulation LR was defined as the highest LR in the ipsilateral anterior circulation arteries. Moderate to severe VSP was defined as LR > 3. Results: Results are shown in table. The probability of VSP in the presence of one anterior circulation vessel LR > 3 is 14 % (2/14), 2 vessels LR >3 (4/16. 16 %), 3 vessels LR > 3 (3/6, 50 %) and 4 vessels LR >3 (5/5 = 100 %). (P< 0.001) Conclusion: LR of M2 MCA has higher sensitivity compared to other vessels and ACA LR has less sensitivity but more specificity whereas the rest of anterior circulation LR had modest predictive value. The likelihood of VSP increases as more number of vessels in anterior circulation shows LR>3. LR should not be interpreted in a blind fashion to the rest of TCD MFV numbers.

Inhibition by theophylline of the early component of canine ventricular contraction

1982 ◽  
Vol 242 (3) ◽  
pp. H349-H358
Author(s):  
M. Endoh ◽  
T. Iijima ◽  
S. Motomura
Keyword(s):  
Mechanical Characteristics ◽  
Calcium Influx ◽  
Myocardial Cell ◽  
Ventricular Muscle ◽  
Late Component ◽  
Ventricular Contraction ◽  
Early Component ◽  
Peak Tension ◽  
Time To Peak ◽  
Plateau Potential

Changes in mechanical characteristics of the isolated canine ventricular muscle were investigated during interaction of isoproterenol with theophylline or caffeine. An early and a late component with time to peak tension of 80 and 150 ms, respectively, were differentiated in a single contraction of the muscle stimulated at 0.5 Hz at 37 degrees C during the interaction of isoproterenol and theophylline, or isoproterenol and caffeine. Isoproterenol increased preferentially the early component and affected only slightly the late one. Theophylline or caffeine elevated the early component less than the late one. In the presence of theophylline + isoproterenol or caffeine + isoproterenol the peak tension was achieved by a late component, whereas the increase in the early one induced by isoproterenol in 3 X 10(-7) M and higher was depressed significantly. During the interaction the rate of twitch relaxation was accelerated further rather than depressed. Changes in action potential indicate that the calcium influx via the myocardial cell membrane during depolarization was increased: the peak plateau potential was significantly elevated by theophylline alone and further by theophylline + isoproterenol. These results indicate that theophylline and caffeine (2 mM) may act intracellularly to inhibit the isoproterenol-induced promotion of the early component without impairing the isoproterenol-induced acceleration of relaxation in the canine ventricular muscle.

Role of the medullary lateral tegmental field in reflex-mediated sympathoexcitation in cats

2004 ◽  
Vol 286 (3) ◽  
pp. R451-R464 ◽  
Author(s):  
Hakan S. Orer ◽  
Gerard L. Gebber ◽  
Shaun W. Phillips ◽  
Susan M. Barman
Keyword(s):  
Nmda Receptor ◽  
Nmda Receptors ◽  
Receptor Antagonist ◽  
Sympathetic Nerve Activity ◽  
Nmda Receptor Antagonist ◽  
Vagal Afferents ◽  
Reflex Pathways ◽  
Excitatory Responses ◽  
Stimulation Of

We tested the hypothesis that blockade of N-methyl-d-aspartate (NMDA) and non-NMDA receptors on medullary lateral tegmental field (LTF) neurons would reduce the sympathoexcitatory responses elicited by electrical stimulation of vagal, trigeminal, and sciatic afferents, posterior hypothalamus, and midbrain periaqueductal gray as well as by activation of arterial chemoreceptors with intravenous NaCN. Bilateral microinjection of a non-NMDA receptor antagonist into LTF of urethane-anesthetized cats significantly decreased vagal afferent-evoked excitatory responses in inferior cardiac and vertebral nerves to 29 ± 8 and 24 ± 6% of control ( n = 7), respectively. Likewise, blockade of non-NMDA receptors significantly reduced chemoreceptor reflex-induced increases in inferior cardiac (from 210 ± 22 to 129 ± 13% of control; n = 4) and vertebral nerves (from 253 ± 41 to 154 ± 20% of control; n = 7) and mean arterial pressure (from 39 ± 7 to 21 ± 5 mmHg; n = 8). Microinjection of muscimol, but not an NMDA receptor antagonist, caused similar attenuation of these excitatory responses. Sympathoexcitatory responses to the other stimuli were not attenuated by microinjection of a non-NMDA receptor antagonist or muscimol into LTF. In fact, excitatory responses elicited by stimulation of trigeminal, and in some cases sciatic, afferents were enhanced. These data reveal two new roles for the LTF in control of sympathetic nerve activity in cats. One, LTF neurons are involved in mediating sympathoexcitation elicited by activation of vagal afferents and arterial chemoreceptors, primarily via activation of non-NMDA receptors. Two, non-NMDA receptor-mediated activation of other LTF neurons tonically suppresses transmission in trigeminal-sympathetic and sciatic-sympathetic reflex pathways.

scholarly journals Breast MRI in Patients with Unilateral Bloody and Serous-Bloody Nipple Discharge: A Comparison with Galactography

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Lucia Manganaro ◽  
Ilaria D’Ambrosio ◽  
Silvia Gigli ◽  
Francesca Di Pastena ◽  
Guglielmo Giraldi ◽  
...  
Keyword(s):  
Nipple Discharge ◽  
Breast Mri ◽  
Bloody Nipple Discharge ◽  
Ductal Cancer ◽  
Malignant Lesions ◽  
Mass Enhancement ◽  
Higher Sensitivity

Purpose. Assessing the role of breast MRI compared to galactography in patients with unilateral bloody or serous-bloody nipple discharge.Materials and Methods. Retrospective study including 53 unilateral discharge patients who performed galactography and MRI. We evaluated the capability of both techniques in identifying pathology and distinguishing between nonmalignant and malignant lesions. Lesions BIRADS 1/2 underwent follow-up, while the histological examination after surgery has been the gold standard to assess pathology in lesions BIRADS 3/4/5. The ROC analysis was used to test diagnostic MRI and galactography ability.Results. After surgery and follow-up, 8 patients had no disease (15%), 23 papilloma (43%), 11 papillomatosis (21%), 5 ductal cancer in situ (10%), and 6 papillary carcinoma (11%) diagnoses. Both techniques presented 100% specificity; MRI sensitivity was 98% versus 49% of galactography. Considering MRI, we found a statistical association between mass enhancement and papilloma (P<0.001; AUC 0.957; CI 0.888–1.025), ductal enhancement and papillomatosis (P<0.001; AUC 0.790; CI 0.623–0.958), segmental enhancement and ductal cancer in situ (P=0.007; AUC 0.750; CI 0.429–1.071), and linear enhancement and papillary cancer (P=0.011).Conclusions. MRI is a valid tool to detect ductal pathologies in patients with suspicious bloody or serous-bloody discharge showing higher sensitivity and specificity compared to galactography.

The role of CT in the diagnosis of sacro-iliitis

1998 ◽  
Vol 39 (3) ◽  
pp. 265-268 ◽  
Author(s):  
M. Geijer ◽  
H. Sihlbom ◽  
J. H. Göthlin ◽  
E. Nordborg
Keyword(s):  
Clinical Symptoms ◽  
Conventional Radiography ◽  
Symptom Duration ◽  
Radiological Findings ◽  
Early Start ◽  
Early Course ◽  
Low Sensitivity ◽  
Higher Sensitivity ◽  
Made In

Objective: Ankylosing spondylitis is a progressive, debilitating disease in which early diagnosis and early treatment can improve the prognosis. Radiographic confirmation is essential for diagnosis but conventional radiography has not proved useful, particularly in the early course of the disease. The aims of this study were to correlate the findings at conventional radiography with those at CT, and to correlate the duration of clinical symptoms with the radiological findings Material and Methods: Forty patients with clinical sacro-iliitis and 13 controls were evaluated by means of conventional radiography and CT Results: Conventional radiography was positive in 10/40 patients and CT in 30/40 patients. Conventional radiography was positive in only 2/14 patients with a symptom duration of less than 2 years while CT was positive in 10/14 such patients Conclusion: The study demonstrated a considerably higher sensitivity in CT than in conventional radiography in detecting the subtle changes necessary for the radiological diagnosis of sacro-iliitis, particularly in cases of short duration. CT allows an early start to be made in treatment with a consequently improved prognosis. The use of conventional radiography cannot be recommended because its low sensitivity delays diagnosis in many instances

Changes in Transmission in Some Reflex Pathways During Movement in Humans

Physiology ◽  
1989 ◽  
Vol 4 (1) ◽  
pp. 29-32
Author(s):  
E Fournier ◽  
P-D Emmanuel
Keyword(s):  
Functional Role ◽  
Voluntary Movement ◽  
Spinal Pathways ◽  
Reflex Pathways ◽  
Spinal Circuitry ◽  
Human Experiments

The gain of the monosynaptic stretch rerflex is controlled by many spinal pathways. Only human experiments allow the exploration of changes in transmission in these pathways during voluntary movement. Unexpected results have been obtained, which have led to new conceptions concerning the functional role of the spinal circuitry.

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