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At least 1,549 records · Page 86Linked to original sources
PubMed1987

Mediators of C5a-induced bronchoconstriction in the guinea pig.

The effect of intravenous injection of C5a on pulmonary resistance and dynamic lung compliance was determined in anesthetized, artificially respirated guinea pigs. A mixture of C5a plus C5ades arg was purified from yeast-activated guinea pig serum and is referred to as C5a. Intravenous injection of C5a caused a dose-related bronchoconstriction as evidenced by a decrease in compliance and increase in resistance. Conversion of the C5a in the mixture to C5ades arg by carboxypeptidase B digestion did not significantly alter the magnitude of the bronchoconstriction. Pharmacological antagonists were employed to determine if histamine, acetylcholine or products of the arachidonate metabolism were mediators of C5a-induced bronchoconstriction. The histamine H1 antagonist pyrilamine inhibited the C5a-induced bronchoconstriction, suggesting the involvement of histamine. The cholinergic receptor antagonist atropine in combination with pyrilamine caused an inhibition of the C5a-induced increase in resistance but not compliance, suggesting acetylcholine does not play a major role in C5a-induced bronchoconstriction beyond its known role in participating in histamine-induced bronchoconstriction. Involvement of arachidonate metabolites was suggested by the ability of the cyclooxygenase inhibitor, indomethacin, to prevent the C5a-induced bronchoconstriction. Because indomethacin also caused a delay in the leukotriene C4 (LTC4)-induced bronchoconstriction, the participation of peptidoleukotrienes in the C5a-induced bronchoconstriction could not be ruled out. The leukotriene antagonists FPL 55712 and L-649,923 were evaluated for their specificity in inhibiting LTC4-induced bronchoconstriction. FPL 55712 was nonselective since it inhibited prostaglandin D2 and histamine-induced bronchoconstriction as well as LTC4-induced bronchoconstriction. L-649,923 inhibited only the LTC4-induced bronchoconstriction and was without effect on the C5a-induced bronchoconstriction, suggesting that peptidoleukotrienes are not important mediators of C5a-induced bronchoconstriction. Using radioimmunoassay, the change in peptidoleukotriene levels detected in plasma during C5a-induced bronchoconstriction was not significantly different from 0. Thus, these studies have quantitated the C5a-induced decrease in dynamic lung compliance and increase in pulmonary resistance and suggest that histamine and cyclooxygenase products, but not peptidoleukotrienes, play a major role in C5a-induced bronchoconstriction.

Acetylcholine↗
PubMed1991

Guinea pig cochlear blood flow under definite sound exposure-hydrogen clearance measurement.

Blood flow measurements were carried out on 18 coloured guinea pigs (8 animals served as control group) before and during definite sound exposure (12 kHz, 110 dB SPL). The exposure time amounted to 60 min. The anaesthesia was carried out according to the following schedule: a mixture consisting of 70 mg alpha-chloralose/kg b.w. and 400 mg urethane/kg b.w. was injected intraperitoneally. The relaxation was performed by means of i.p. application of 3 mg Tricuran/kg b.w./h. The hydrogen clearance measurements (HCM) were carried out under artificial respiration with control of arterial pH, endexpiratory CO2 content, as well as blood pressure and body temperature. After a duration of noise exposure of 30-45 min the cochlear blood flow reached an average level of 80% of the initial point. This level remained mainly unchanged until the end of noise exposure (60 min). Our HMC's confirm Laser Doppler flowmetry findings.

Acoustic Stimulation↗
PubMedDate not supplied

Effects of hyperventilation and hypoventilation on cochlear blood flow and endocochlear direct-current potential.

To understand the importance of oxygen transport to the inner ear tissue, we studied, in guinea pigs, the relationship between cochlear blood flow and endocochlear direct-current potential (EP) under different respiratory conditions. EP, a functional parameter of the stria vascularis, was recorded by a microelectrode inserted into the lateral wall of the chochlea. To measure the cochlear blood flow (CoBF), we employed laser Doppler flowmetry and recorded the flow with a probe placed on the same spot on the lateral wall. During 3 min of asphyxia, CoBF and systemic blood pressure showed irregular biphasic increases, while the EP decreased to reach a negative value. In the hypoxemia experiment, which was induced by stepwise reduction of the respiratory rate to 60%, increases in CoBF and blood pressure were evident during hypoventilation with an intermediate position of EP in the positive range. The mechanisms of these increases in two parameters are discussed from the viewpoints of sympathicotonic activity in the autonomic nervous system and the vasodilating action of CO2 during hypercapnia. In the hyperoxemia experiment, which was induced by stepwise increase in the respiratory rate to 140%, CoBF and blood pressure were found to decrease during hyperventilation with no significant change of EP. The decrease in blood pressure was considered to be due to the increase in intrathoracic pressure caused by the increased rate of artificial respiration. As for the concomitant decrease in CoBF, chemical regulation of PCO2 in the vascular bed of the lateral wall of the cochlea was thought to be a contributory factor.

Animals↗
PubMed1999

Changes in respiratory mechanics during abdominal laparoscopic surgery in children.

We designed this study in order to measure the changes in respiratory mechanics during laparoscopic surgery in children. Ventilation parameters (Flow (Ví) and Peak Pressure (Pmax)) were measured and total respiratory system mechanics (resistance (Rrs) and compliance (Crs)) were derived using multiple linear regression analysis in 11 children aged 8 months to 11 years. The Pmax increased by 26.6% and the Rrs increased by 20.2% whilst the Crs decreased by 38.9% after pneumoperitoneum. These findings suggest that clinically important changes in respiratory mechanics occur as a result of the pneumoperitoneum produced during abdominal laparoscopic surgery.

Abdomen↗
PubMed2005

Feasibility of continuous CO2 removal with hydrophilic membranes at low blood flow rates.

In the conventional treatment of acute respiratory distress syndrome (ARDS), high O2 concentrations and mechanical ventilation may damage the lung tissue. Extracorporeal membrane oxygenation limits damage, provides the needed O2 supply and improves survival of ARDS neonates, but not of adults. Hydrophilic membranes used in hemodialysis are more non-thrombogenic and biocompatible than those used in blood oxygenation, but their O2 transport capacity is not as high. In recent years, CO2 removal at low blood flow rates combined with apneic oxygenation and low frequency ventilation has proved promising in the treatment of ARDS. This approach makes O2 supply across ECMO membranes unnecessary; it also makes hydrophilic membranes candidates for extracorporeal CO2 removal to minimize anticoagulation and immune system activation. This paper reports on the in vitro capacity of hydrophilic polysulphone membranes to remove CO2 from carbonated pig blood into an oxygen-rich gas stream. Experiments were performed on clinical-size dialysis modules and their capacity to remove CO2 as a function of blood flow rate and membrane surface area was investigated. Membranes effectively removed CO2 , more so at increasing blood flow rates and membrane surface areas, at rates of up to 15% of the CO2 metabolic production rate. The specific CO2 removal rate was comparable to that of blood oxygenators equipped with microporous hydrophobic membranes. It is concluded that CO2 removal from slowly flowing blood with hydrophilic membranes is feasible.

Animals↗
PubMed2001

Transdermal fentanyl for the management of cancer pain: a survey of 1005 patients.

Transdermal fentanyl was released in Germany in 1995. From October 1996 to February 1998 transdermal treatment was documented for 1005 patients (506 men and 499 women with a mean age of 60 years, range 20-92 years) with chronic pain in an open survey including 290 physicians from hospitals and general practitioners throughout Germany. Most patients suffered from cancer pain and only 11 patients had chronic pain from non-malignant disease. Physicians were asked to complete a questionnaire for patients treated with transdermal fentanyl on initiation of therapy (day 0), and days 3, 6, 18, 30 thereafter, followed by monthly follow-up intervals. Patients were asked to complete a pain diary. Transdermal therapy was documented from day 0 for 824 patients, while 181 patients had been treated with transdermal fentanyl before admission in the survey. Most of the other 824 patients had been treated with other step 3 opioids (55% of the patients) or step 2 opioids (23%) before conversion to transdermal fentanyl, whereas 8% had been treated only with non-opioids and 14% had received analgesics only as required or not at all before initiation of transdermal therapy. The most important reasons for switching to transdermal opioid therapy were insufficient pain relief with the previous medication followed by a variety of gastrointestinal symptoms impeding oral analgesic therapy. Initial fentanyl doses ranged from 0.6 to 9.6 mg/day (25 to 400 microg/h) with a median of 1.2 mg/day (50 microg/h). Median doses slowly increased throughout the observation period to 2.4 mg/day (100 microg/h) after 4 months of treatment. Most patients continued transdermal therapy until the time of death (47% of patients). Other reasons for discontinuation were inadequate pain relief (10%), pain relief with other analgesic regimens (10%), other symptoms than pain (5%), rejection of transdermal therapy by the patient (6%) or miscellaneous (16%). Adverse events were documented as the reason for discontinuation of transdermal therapy in 49 patients (5%). Dyspnoea was documented for seven patients as the reason for discontinuation. One of these patients, as well as another patient with an episode of apnoea, had to be treated with artificial respiration for several hours, but both patients recovered without sequelae. Transdermal therapy with fentanyl was safe and efficient in this national survey. Transdermal fentanyl can be recommended for treatment of moderate to severe cancer pain and probably may even be used as a first-line drug on step 3 of the World Health Organization recommendations in selected patient groups.

Administration, Cutaneous↗
PubMed1982

Enzymologic studies and therapy of Leigh's disease associated with pyruvate decarboxylase deficiency.

An 11-month-old boy with muscle hypotonia and neurologic deteriorations had lactic acidosis, pyruvic acidemia and alaninemia due to deficiency of the pyruvate dehydrogenase complex in his platelets and of pyruvate decarboxylase in his muscle. When placed on a low carbohydrate-high fat diet for 6 months, his blood levels of lactate and pyruvate became nearly normal, but his cerebrospinal fluid levels of lactate and pyruvate remained high. Despite this dietary therapy, neurologic deterioration progressed slowly. He died of pneumonia after artificial respiration for 3 wk. At autopsy, extensive symmetric lesions were found in the brain including proliferation of capillaries and gliosis in the brain stem and diffuse demyelination in the white matter. These lesions were consistent with those observed in Leigh's disease. The activities of the pyruvate dehydrogenase complex and pyruvate decarboxylase in various tissues obtained at autopsy were less than 10% of control values; however, the activities of pyruvate carboxylase and alpha-ketoglutarate decarboxylase were within the normal limits. This patient with Leigh's disease had an isolated deficiency of pyruvate decarboxylase in various tissues.

Blood Platelets↗
PubMed1982

Vasopressin-dependent and -independent control of the release of adrenocorticotropin.

We tested the possibility that vasopressin mediates the responses of adrenocorticotropin (ACTH) to electrical stimulation of various areas of the hypothalamus. Thirty-three cats were anesthetized with chloralose-urethane, immobilized with gallamine, and respired artificially. Plasma ACTH was measured by RIA. Intraventricular administration of antiserum to vasopressin blocked the release of ACTH induced by electrical stimulation of the paraventricular nucleus (PVN), suggesting a role for the vasopressinergic projection from PVN to the external zone of the median eminence. In contrast, the release of ACTH induced by stimulation of areas ventral to PVN was unaffected by the antiserum. Thus, there is at least one corticotropin releasing factor released from nuclei other than PVN that is distinct from vasopressin.

Adrenocorticotropic Hormone↗
PubMed1987

Hyperglycemia, cerebrospinal fluid lactic acidosis, and cerebral blood flow in severely head-injured patients.

Cerebrospinal fluid (CSF) lactate concentration is known to increase during the acute phase after severe head injury. To determine the influence of glycemia or cerebral ischemia on this lactate increase, we studied 69 head-injured patients aged 28.7 +/- 15.4 (SD) years with a mean Glasgow coma score of 5.7 +/- 1.7 (SD). They were intubated, paralyzed, and artificially respired. We measured lactate and glucose concentrations in ventricular CSF (VCSF), arterial blood, and jugular bulb blood for 5 days. Samples were obtained within 12 hours after injury and at regular 12-hour intervals. These patients were not treated for hypo- or hyperglycemia. Cerebral blood flow (CBF) was also measured within 12 hours and at 12- to 48-hour intervals. Hyperglycemia was found consistently within 12 hours after injury (224 +/- 98 mg/dl, P less than 0.001), and mild hyperglycemia persisted during the entire period of study. The VCSF glucose course was parallel to that in blood (the initial VCSF glucose value was 128 +/- 37 mg/dl, P less than 0.001). The blood lactate value was also elevated during the first 12 hours (4.2 +/- 2.0 mmol/litre, P less than 0.001), normalizing within 24 to 36 hours. The VCSF lactate course was independent from that of the blood lactate value. It was significantly elevated within 12 hours after injury (5.3 +/- 2.6 mmol/litre, P less than 0.001) and remained so during the 5 days of study. A high initial VCSF glucose value was associated with a high initial VCSF lactate value. However, a high VCSF lactate concentration was present even when the glucose value was close to the normal level.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1995

Transcranial Doppler and cortical microcirculation at increased intracranial pressure and during the Cushing response: an experimental study on rabbits.

The effect of increased intracranial pressure on the flow velocity of the basilar artery was measured with transcranial ultrasonic Doppler in New Zealand White rabbits under alpha-chloralose anesthesia and artificial respiration. Laser Doppler flowmetry served to study changes of the cortical microcirculation. The results confirm a high inverse correlation of the diastolic flow velocity, the pulsatility index, and the resistance index with the cerebral perfusion pressure (CPP). During acute intracranial hypertension, however, these parameters do not show a good correlation with the local cortical blood flow. The absence of a correlation was evident over a wide CPP range down to values of 35 mm Hg. Only at CPP values below this critical threshold is the microcirculation impaired. The threshold is reached at pulsatility index values of more than 2.0 and at resistance index values of more than 0.8. Therefore, transcranial Doppler indices permit the detection of critical reductions of microcirculatory blood flow. The Cushing reaction occurred with a constant time lag of 5.5 +/- 0.7 seconds after the loss of CPP. The Cushing reaction did not establish systolic blood flow, which remained below the functional threshold, as concluded from the temporary loss of somatosensory evoked potentials.

Animals↗
PubMed1982

Induction and suppression of aminosulfonic acid spikes in Wulst EEG of adult chickens.

In order to learn the effects of a series of aliphatic omega-aminosulfonic acids with varying numbers of carbon chains, changes in the electroencephalogram (EEG) of adult hen were investigated as the criteria. The drug solution (10 microliters) was locally injected into the telencephalon of a curarized animal under artificial respiration and Wulst EEG was recorded near the administered region. No influence was seen on EEG by the administration of amino acids with 1-3 carbon chains (short-chain structure) at a concentration of 6 X 10(-1)M. Characteristic biphasic spikes developed after the administration of amino acids with 4 or more carbon chains (long-chain structure) at a concentration higher than 2 X 10(-2)M, and their amplitudes gradually increased over 1.5-2.0 mV. Spikes were induced by guanyl compounds of amino acids of long-chain structure even at a concentration of 2 X 10(-3)M. Convulsant drugs also induced spikes when used in doses similar to the spike-inducing omega-aminosulfonic acids. The development of spikes by omega-aminosulfonic acids was antagonized by aminosulfonic acids with a short-chain structure. On the basis of the above-mentioned results, omega-aminosulfonic acids can be classified into excitants and depressants according to their activities in inducing characteristic spikes with high amplitudes. In the development of spikes, the excitants and depressants are antagonistic to each other. The doses of excitants which induce spikes are comparable to those of convulsants and coincide very well with the earlier reported relationship between convulsion development rates of excitants and dosage administered to the cerebral ventricle of mice.

Alkanesulfonates↗
PubMed1982

Protective effect of flunarizine against cerebral hypoxia-anoxia in mice and rats.

The protective effect of flunarizine against cerebral hypoxia-anoxia was investigated with various experimental models in mice and rats. The effect of flunarizine was compared with those of cinnarizine, verapamil and pentobarbital. The oral treatment of animals with flunarizine resulted in a consistent and long-lasting-protection against cerebral hypoxia-anoxia in all the models examined: Cytotoxic anoxia by KCN injection, hypercapnic anoxia induced by stopping artificial respiration, hypobaric hypoxia and normobaric hypoxia. The minimal effective dose of flunarizine was 1 to 20 mg/kg. The activity of flunarizine was 4 to 30 times as potent as that of cinnarizine and pentobarbital. Verapamil showed little or no protective effect. The mode of action of flunarizine was different from that of pentobarbital, which showed protection at anaesthetizing doses. These results indicate that flunarizine possesses a universal protective effect against cerebral hypoxia-anoxia, through the mechanism involved remains to be clarified. Hence, it is suggested that flunarizine might exert a beneficial effect on oxygen insufficiency of the brain resulting from cerebral ischemia.

Animals↗
PubMed1989

A case of myocardial damage following acute paracetamol poisoning.

A 24-year-old woman was admitted to our hospital with acute paracetamol poisoning, and severe hepatic injury. The peak blood level of GOT, GPT and LDH were 32,600 U, 119,200 U and 36,500 U respectively. Glucagon-insulin and glutathione were administered to save the liver function. On the third hospital day, hemodialysis was administered to treat acute renal failure. On the 16th hospital day, when the liver and renal functions recovered, severe pulmonary congestion occurred and right heart catheterization revealed high pulmonary pressure. Echocardiography showed left ventricular enlargement accompanied by a severe diffuse impairment of left ventricular wall motion. Multi-focal ventricular arrhythmia was frequent during this period. Hemodialysis and artificial respiration were carried out for the treatment of heart failure. Three months after admission, myocardial perfusion scintigram showed patchy reduction in the uptake of Tl-201 throughout the myocardium, and left ventriculography showed mild diffuse impairment of the LV wall motion (ejection fraction: 49%). In this case, acute heart failure appeared approximately 2 weeks after the severe hepatic injury. Apparently myocardial damage following paracetamol overdosage is caused not only by direct toxicity but by severe metabolic derangement.

Acetaminophen↗
PubMed1996

Chaotic musical murmur in aortic regurgitation.

We report an interesting case of aortic regurgitation. Phonocardiographically, the shape of the diastolic musical murmur in this case changed in each cardiac cycle despite being in sinus rhythm, in the same posture and in the same breathing phase. Experimentally, we were able to obtain a similar noise pattern using an artificial respirator and a hemispherical silicone membrane. We concluded that the irregular and chaotic change in the shape of the diastolic musical murmur in the present case occurred due to irregular swaying of the non-coronary cusp under the influence of the Venturi effect owing to a regurgitant jet stream.

Aortic Valve↗
PubMed1998

[A method of measuring eruptive movement of the rat incisor using a non-contacting displacement detector].

The axial movements of rat incisors were recorded continuously for over 20 hr. The rats were anesthetized with halothane delivered by intratracheal intubation using an artificial respirator. A hemostatic clamp was used to immobilize the jaw. The displacement detector that detects changes in the electric eddy current exhibited high resolution, good linearity and low drift. The average eruption rates of the rat incisor were estimated to be 406 and 516 microns/ 24 hr at 34 and 37 degrees C of the rectal temperature, respectively. The values were within the normal range. We also measured the force needed to restrain eruptive movement of the rat incisor using the same apparatus combined with a load cell. The maximum pushing force was estimated to be 9 mN or 29 mmHg (converted value) on average. Then the effects of adrenaline on axial movement of the incisor and arterial blood pressure were examined. Adrenaline caused a rapid extrusive tooth movement with a nearly simultaneous increase in the blood pressure, followed by a marked intrusive tooth movement and a decrease in blood pressure. These results support the view that the systemic arterial blood pressure and vasculature in the tooth socket play important roles to determine the position of teeth. We assume that our method would be useful to clarify the precise relationship between tooth displacement and vascular change in the tooth socket.

Alveolar Process↗