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PubMed1986

Some characteristics of ruminants and swine that complicate management of general anesthesia.

Successful anesthetic management of food animals depends on knowledge of basic principles and techniques of anesthesia common to most species. When specifically considering food animals, additional emphasis is directed toward animal size, temperament, and anatomy. Respiratory failure induced by a variety of mechanisms is a major complication of special importance in ruminants. Problems relate especially to difficulty of endotracheal intubation, inhalation of saliva and rumen contents, and reduced lung gas volume caused by abdominal organ (especially rumen)-induced cranial diaphragmatic displacement. When evaluating swine for anesthesia, specific additional management considerations include accessibility of peripheral blood vessels, ease of endotracheal intubation, and porcine malignant hyperthermia.

Anesthesia, General↗

PubMed2006

Perioperative vasovagal syncope with focus on obstetric anesthesia.

Vasovagal syncope refers to a reflex cardiovascular depression that gives rise to loss of consciousness with bradycardia and profound vasodilatation. This response commonly occurs during regional anesthesia, hemorrhage or supine inferior vena cava compression in pregnancy. The changes in circulatory response from the normal maintenance of arterial pressure to parasympathetic activation and sympathetic inhibition may cause severe hypotension. This change is triggered by reduced cardiac venous return as well as episodes of emotional stress, excitement or pain. Occasionally, these vasovagal responses may be unpredictable and may dramatically proceed to asystole with circulatory collapse, and may even result in death. In these circumstances, hypotension may be more severe than that caused by bradycardia alone, because of unappreciated vasodilatation. Regional anesthesia, decreased venous return, hemorrhage and abnormal fetal presentation cumulatively increase the risk of vasovagal syncope in cesarean section patients. When a vasovagal response occurs, ephedrine is the drug of first choice because of its combined action on the heart and peripheral blood vessels. Epinephrine must be used early in established cardiac arrest, especially after high regional anesthesia.

Anesthesia, Epidural↗

PubMed1994

Determination of the earliest appearance and peak count of microfilariae of Wuchereria bancrofti and Brugia malayi after taking a single dose of diethylcarbamazine at noon.

Six nocturnal microfilarial carriers (three with Wuchereria bancrofti and three with Brugia malayi) from mainland China were selected to determine the earliest appearance and peak count of microfilariae (mf) administration of DEC at noon. Before diethylcarbamazine (DEC) administration, blood samples of 60 microliters were obtained by finger-prick at 2 h intervals for 24 h. A blood sample was then taken just before each carrier intaking 100 mg, 150 mg or 200 mg of DEC orally at noon. After drug administration, blood samples were obtained at 45 and 60 sec and at 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, 50, 60, 90 and 120 min. Samples were then taken at 2 h intervals for the next 2 h and at 6 h intervals for the next 7 days. Both W. bancrofti and B. malayi showed typical nocturnal periodicity. One mf was first detected in the peripheral blood 45 sec in a mf. carrier. The mf peak counts were found 1-40 min after DEC administration at noon. The nocturnal cycle was distributed during the first two days after DEC administration. It became regular with a much lower peak count by the third day after administration. The results of the present study indicate that the provocative effect of DEC on the mf is very fast; the first appearance in the peripheral blood vessels could be under 45 sec.

Animals↗

PubMed2000

Tight junctions of the blood-brain barrier.

1. The blood-brain barrier is essential for the maintenance and regulation of the neural microenvironment. The blood-brain barrier endothelial cells comprise an extremely low rate of transcytotic vesicles and a restrictive paracellular diffusion barrier. The latter is realized by the tight junctions between the endothelial cells of the brain microvasculature, which are subject of this review. Morphologically, blood-brain barrier-tight junctions are more similar to epithelial tight junctions than to endothelial tight junctions in peripheral blood vessels. 2. Although blood-brain barrier-tight junctions share many characteristics with epithelial tight junctions, there are also essential differences. However, in contrast to tight junctions in epithelial systems, structural and functional characteristics of tight junctions in endothelial cells are highly sensitive to ambient factors. 3. Many ubiquitous molecular constituents of tight junctions have been identified and characterized including claudins, occludin, ZO-1, ZO-2, ZO-3, cingulin, and 7H6. Signaling pathways involved in tight junction regulation comprise, among others, G-proteins, serine, threonine, and tyrosine kinases, extra- and intracellular calcium levels, cAMP levels, proteases, and TNF alpha. Common to most of these pathways is the modulation of cytoskeletal elements which may define blood-brain barrier characteristics. Additionally, cross-talk between components of the tight junction- and the cadherin-catenin system suggests a close functional interdependence of the two cell-cell contact systems. 4. Recent studies were able to elucidate crucial aspects of the molecular basis of tight junction regulation. An integration of new results into previous morphological work is the central intention of this review.

Animals↗

PubMed2001

Acute effects of angiotensin II on myocardial performance.

BACKGROUND: Specific angiotensin II (Ang II) receptors exist in many organs including peripheral blood vessels, cardiac myocytes and the central nervous system. This suggests multiple sites of actions for Ang II throughout the cardiovascular system. Cardiac effects of Ang II are not completely understood, though its prominent vasoconstrictor actions are well described. This study was designed to assess left ventricular function during administration of Ang II using relatively load-independent methods in a whole-animal model. METHODS: Ang II was infused in incremental doses (0-200 microg x h(-1)) in anaesthetised instrumented pigs (n=10). Cardiac systolic and diastolic function were evaluated by analysis of the left ventricular pressure-volume relationship. RESULTS: Heart rate (HR), mean arterial pressure (MAP) and systemic vascular resistance (SVR) increased dose-dependently with Ang II, while cardiac output (CO) remained unchanged. Systolic function indices, end-systolic elastance (Ees) and preload recruitable stroke work (PRSW), demonstrated dose-dependent increases. The diastolic function parameter tau (tau) did not change with increasing Ang II dose. CONCLUSION: Ang II infusion caused increases in contractility indices in anaesthetised pigs in the doses used in this study. The mechanisms for these systolic function effects may be a direct myocardial effect or modulated through changes in autonomic nervous system activity.

Angiotensin II↗

PubMed1983

Pafenolol, a highly selective beta 1-adrenoceptor-antagonist, in asthmatic patients: interaction with terbutaline.

Pafenolol, a new beta 1-adrenoceptor antagonist, has been shown in animals to be more selective for beta 1-adrenoceptors than metoprolol. It was studied in asthmatic patients to evaluate whether it was more selective with respect to circulatory effects and especially whether this selectivity influenced bronchial muscle tone less than metoprolol, which has been shown to have beta 1-adrenoceptor selectivity similar to that of atenolol. Intravenous pafenolol (5 mg and 7.5 mg), metoprolol (15 mg), and saline were given double-blind at random and thereafter four increasing doses of terbutaline were given intravenously to seven asthmatic patients with reproducible reversibility of airways obstruction. After the terbutaline dose-response curve was determined, terbutaline was inhaled three times in increasing doses. A separately reported exercise study in the same patients showed that 5 mg pafenolol and 15 mg metoprolol were equipotent with respect to beta 1-adrenoceptor blockade, whereas 7.5 mg pafenolol tended to increase the blockade. The reflex tachycardia on terbutaline stimulation after pafenolol was greater than after metoprolol due to less blockade of beta 2-adrenoceptors in peripheral blood vessels. The bronchial effect of pafenolol was equal to that of saline, but there was a difference between the terbutaline dose-response curves after pafenolol and metoprolol that caused a rightward shift of the dose-response curve. Thus, pafenolol was shown to be more beta 1-selective than metoprolol.

Adrenergic beta-Antagonists↗

PubMed1983

Hypokalaemia stimulates prostacyclin synthesis in the rat.

1. To examine the hypothesis that the normalcy of blood pressure, despite an increase in circulating angiotensin II, and the blood pressor hyporesponsiveness to infusion of pressor agents which are associated with hypokalaemia, are due to overproduction of prostacyclin, the principal prostaglandin (PG) synthesized by the vascular endothelium, we studied the effect of experimental hypokalaemia on the urinary excretion of immunoreactive 6-keto-prostaglandin F1 alpha, a stable metabolite of prostacyclin, in the rat. 2. The animals were fed on a potassium-deficient diet for 9 days. Twenty-four hour urine samples were collected daily for measurement of urinary excretion of immunoreactive 6-keto-PGF1 alpha, PGE2 and 13,14-dihydro-15-keto-PGF2 alpha (PGFM). 3. Hypokalaemia caused significant increases of the three prostaglandins measured. 4. We conclude that hypokalaemia is a potent stimulus of both renal and vascular prostaglandins. The results suggest that an increase in prostacyclin synthesis in peripheral blood vessel walls may be responsible for the resistance of blood pressure to infusion of pressor substances as well as for the normalcy of blood pressure, despite the presence of high circulating angiotensin II concentrations, in conditions associated with hypokalaemia.

6-Ketoprostaglandin F1 alpha↗

PubMed1997

Regulation of angiogenesis by hypoxic stress: from solid tumours to the ovarian follicle.

The preovulatory follicle provides a unique physiological example of rapid growth accompanied by neovascularization, two processes that are generally characteristic of pathologies such as wound repair or malignancy. During the hours preceding ovulation, follicular growth is accompanied by elevated levels of messenger RNA for vascular endothelial growth factor (VEGF). Angiogenic activity, mediated by VEGF, is manifested in the peripheral blood vessels surrounding the follicle, that show capillary sprouting and increased vascular permeability. Following ovulation, rapid infiltration of capillaries through the follicular wall is essential for the formation of the corpus luteum. In this review we compare the preovulatory follicle with a popular model of avascular solid tumour growth, namely the multicellular tumour spheroid, in particular the role of hypoxic stress in the regulation of angiogenesis in both systems.

Cell Hypoxia↗

PubMed2001

Investigations into migraine pathogenesis: time course for effects of m-CPP, BW723C86 or glyceryl trinitrate on appearance of Fos-like immunoreactivity in rat trigeminal nucleus caudalis (TNC).

Clinical and preclinical studies suggest that 5-HT and nitric oxide (NO) mobilization within the trigeminovascular system is fundamental to the initiation of migraine attacks., e.g. m-chlorophenylpiperazine (m-CPP) and glyceryl trinitrate (GTN) induce headache in humans. 5-HT2B receptors are known to mediate NO-dependent vasorelaxation in peripheral blood vessels, raising the possibility that this receptor is implicated in the pathogenesis of the disease. Therefore, we measured the effects of 5-HT2B agonists (m-CPP or BW723C86) or GTN on trigeminal nerves by quantifying Fos expression in the rat TNC. m-CPP (0.1 mg/kg, i.v.) induced time-dependent elevations in Fos-LI in the rat TNC 2 h and 8 h after injection. In contrast, neither intravenous GTN (0.5 microg/kg per min, infused 20 min) nor BW723C86 (0.1 mg/kg, i.v.) increased Fos-LI at 2 h or 8 h after administration. These data are not consistent with the involvement of the 5-HT2B/2C receptors or NO in trigeminovascular activation, and by inference migraine, and suggest the contribution of some other unidentified pathway.

Animals↗

PubMed1990

The filaria Litomosoides galizai in mites; microfilarial distribution in the host and regulation of the transmission.

The mites, Bdellonyssus bacoti, are engorged on rodents having 800 to 60,000 microfilarie/10 mm3 blood. Quantitation of L. galizai larval development shows that an additional blood meal improves development and that high microfilaremiae do not result in a proportional increase in the number of infective larvae. The first important stage of transmission regulation occurs during ingestion of microfilariae: the numbers of ingested microfilariae are lower than expected in cases of high microfilaremia. This phenomenon cannot be ascribed to the mite vector that engorges a constant blood meal whatever the level of microfilaremia. Contrarily, one finds that microfilarial density in the small peripheral blood vessels (blood drawn from incision of the dorsal skin) increases less than in large blood vessels (retro-orbital sinus). A similar observation was reported by Dickerson et al. (1989) working with Wuchereria bancrofti. We assume that in both cases, the high microfilaremiae cause the small blood vessles accessible to the vector to become saturated with parasites. Although regulation during engorging is not the sole factor to monitor the infection in B. bacoti (another one operates during larval development of L. galizai), demonstrating its existence seems to us fundamental: it points out the concept that sub-ingestion, as well as over-ingestion, shows the inequalities of microfilarial densities in the host which seem to be dependent on mechanical factors such as the diameter of blood vessles and the size of microfilariae.

Animals↗

PubMed1978

[Cystic adventitial degeneration of radial artery (author's transl)].

The cystic adventitial degeneration of peripheral blood vessels is a rare lesion with unknown etiology and pathogenesis. The lesions are most frequent with a predominantly unilateral manifestation in the popliteal artery. The own observations included a rare affection of the radial artery. The literature relating to this condition has been reviewed. Etiology and histogenesis of the arterial alterations have been discussed.

Adult↗

PubMed2005

[Comparison of the sonographic detection of experimentally induced squamous cell carcinoma compared with the histological image].

BACKGROUND: Malignant tumours of the head and the neck are characterised by typical signs of malignancy in greyscale- and colour-coded sonography. Sometimes, such criteria cannot be verified, and in such cases it remains unclear whether typical changes do not exist or whether we just cannot detect them with our high-end ultrasound units. We therefore compared our sonographical findings with the histology obtained in experimentally induced tumours. METHODS: Experimental squamous cell carcinoma was induced subcutaneously in nude mice (n = 18), using four different cell lines. Ultrasound examination of the tumours was performed after 98 and 112 days, respectively, Central necrosis, rupture of the capsule as well as the presence of central and peripheral blood vessels were documented before the tumours were excised. They were then sliced in the same direction as sonography had been carried out before. Blood vessels were stained using CD31. RESULTS AND DISCUSSION: 16 tumours grew subcutaneously. In ultrasound imaging, the capsule was always intact, and subcapsular vessels were detected in every tumour. Central necrosis was seen in 10/16 tumours by sonography, but in 15/16 tumours on histological examination. The failure of sonography in detecting necrosis did not correlate with the size of the tumour. Centrally located vessels were found in 12/16 tumours using colour-coded sonography. Histology, however, showed their presence in all 16 tumours. Interestingly, the failure of sonography in detecting vessels did not correlate with tumour size. It seemed that the detection of such vessels was particularly difficult in those tumours which grew very fast. This finding explains why we often find such vessels in small tumours but not in large specimens, where they would normally be expected.

Animals↗

PubMed1995

Whole-body protochordate regeneration from totipotent blood cells.

Cell differentiation, tissue formation, and organogenesis are fundamental patterns during the development of multicellular animals from the dividing cells of fertilized eggs. Hence, the complete morphogenesis of any developing organism of the animal kingdom is based on a complex series of interactions that is always associated with the development of a blastula, a one-layered hollow sphere. Here we document an alternative pathway of differentiation, organogenesis, and morphogenesis occurring in an adult protochordate colonial organism. In this system, any minute fragment of peripheral blood vessel containing a limited number of blood cells isolated from Botrylloides, a colonial sea squirt, has the potential to give rise to a fully functional organism possessing all three embryonic layers. Regeneration probably results from a small number of totipotent stem cells circulating in the blood system. The developmental process starts from disorganized, chaotic masses of blood cells. At first an opaque cell mass is formed. Through intensive cell divisions, a hollow, blastula-like structure results, which may produce a whole organism within a short period of a week. This regenerative power of the protochordates may be compared with some of the characteristics associated with the formation of mammalian embryonal carcinomous bodies. It may also serve as an in vivo model system for studying morphogenesis and differentiation by shedding more light on the controversy of the "stem cell" vs. the "dedifferentiation" theories of regeneration and pattern formation.

Journal Article↗

PubMed1998

Mutual link among the approaches to clipping of basilar aneurysms.

The pterional approach for basilar aneurysm clipping, has become the most common approach among surgeons, since it was advocated by Yasargil in 1982. However, other approaches aiming at an adequate but less invasive surgery to meet conditions of peripheral blood vessels (including aneurysmal size, direction and perforating arteries and arteriosclerosis) and the direction of clip insertion have also been developed. The approaches will be recommended to be expanded according to situations of the actual intra-operative findings in the future. The mutual link among the approaches to clipping of basilar aneurysms was investigated.

Adult↗

PubMed2004

L-arginine prevents impaired endothelium-dependent cerebral arteriolar dilatation during acute infusion of nicotine.

Exogenous treatment with L-arginine has been shown to restore impaired nitric oxide synthase (NOS)-dependent dilatation of peripheral blood vessels during disease states. We have shown that nicotine impairs NOS-dependent arteriolar dilatation in the cerebral circulation. However, the role of L-arginine in impaired responses of cerebral arterioles during infusion of nicotine has not been examined. Thus the goal of the present study was to examine the role of L-arginine in nicotine-induced impairment of cerebral arteriolar reactivity. We measured the diameter of pial arterioles in response to NOS-dependent (5'-adenosine diphosphate [ADP] and acetylcholine) and NOS-independent (nitroglycerin) agonists before and after infusion of vehicle or nicotine (2 microg/kg/min intravenously for 30 min followed by a maintenance dose of 0.35 microg/kg/min) in the absence or presence of L-arginine (10(-3) M). We found that topical application of L-arginine to cerebral microvessels during infusion of nicotine could prevent impaired NOS-dependent vasodilatation. We suggest that exogenous L-arginine may have a beneficial role in preventing cerebral microvascular dysfunction during exposure to nicotine.

Animals↗

PubMed1995

Effect of cyclic phenyl saligenin phosphate and paraoxon treatment on vascular response to adrenergic and cholinergic agents in hens.

The response of peripheral blood vessels to adrenergic and cholinergic agonists was examined 1, 3, 7, and 21 d after hens were treated with a single intramuscular injection of 2.5 mg/kg cyclic phenyl saligenin phosphate (PSP) or 0.10 mg/kg paraoxon (PXN). These two organophosphates (OPs) cause different clinical effects in exposed animals, as PSP causes organophosphate-induced delayed neuropathy (OPIDN) and PXN causes acute poisoning through inhibition of acetylcholinesterase. For these studies, the ischiadic artery was cannulated both prograde and retrograde and the blood was shunted through a pump to maintain a constant flow. Alterations in pressure measured at the pump outflow were used to indicate changes in limb vascular resistance. Dose-response curves were generated for the response to intravenous administration of acetylcholine (ACh), phenylephrine (PE), or salbutamol (SAL) (10(-8) to 10(-4) mol/kg). Acetylcholine at 10(-8) to 10(-7) mol/kg caused an increase in vascular resistance, whereas concentrations of 10(-5) to 10(-4) mol/kg caused a decrease in vascular resistance in hens given PSP 1 and 3 d previously. The response of PXN-treated hens to ACh was not significantly altered from that of vehicle-treated hens. The resistance generated in response to PE, an alpha 1-adrenergic agonist, in PSP-treated hens was greater than levels in vehicle-treated hens on d 1 and 3 and greater than the response seen in hens treated with PXN. Salbutamol, a beta 2-adrenergic agonist, at concentrations of 10(-7) to 10(-4) mol/kg caused an increase in resistance 1 and 3 d after PSP and a decrease on d 7. The responses to SAL were different in PXN-treated hens, as these hens demonstrated a lesser increase in resistance at concentrations of 10(-8) to 10(-7) mol/kg and a decrease in resistance at 10(-5) to 10(-4) mol/kg 1 d after administration of PXN. These observations indicate that response to vasoactive agents is altered in OP-treated hens and that responses differ between a compound capable of causing OPIDN (PSP) and a compound that only causes acute effects (PXN).

Adrenergic Agents↗

PubMed2001

Perioperative bradycardia and asystole: relationship to vasovagal syncope and the Bezold-Jarisch reflex.

Reflex cardiovascular depression with vasodilation and bradycardia has been variously termed vasovagal syncope, the Bezold-Jarisch reflex and neurocardiogenic syncope. The circulatory response changes from the normal maintenance of arterial pressure, to parasympathetic activation and sympathetic inhibition, causing hypotension. This change is triggered by reduced cardiac venous return as well as through affective mechanisms such as pain or fear. It is probably mediated in part via afferent nerves from the heart, but also by various non-cardiac baroreceptors which may become paradoxically active. This response may occur during regional anaesthesia, haemorrhage or supine inferior vena cava compression in pregnancy; these factors are additive when combined. In these circumstances hypotension may be more severe than that caused by bradycardia alone, because of unappreciated vasodilation. Treatment includes the restoration of venous return and correction of absolute blood volume deficits. Ephedrine is the most logical choice of single drug to correct the changes because of its combined action on the heart and peripheral blood vessels. Epinephrine must be used early in established cardiac arrest, especially after high regional anaesthesia.

Afferent Pathways↗

PubMed1998

Mapping the genome of a model protochordate. I. A low resolution genetic map encompassing the fusion/histocompatibility (Fu/HC) locus of Botryllus schlosseri.

The colonial protochordate, Botryllus schlosseri, undergoes a genetically defined, natural transplantation reaction when the edges of two growing colonies interact. Peripheral blood vessels of each colony touch and will either fuse together to form a common vasculature between the colonies, or reject each other in an active blood-based inflammatory process in which the interacting vessels are cut off and the two colonies no longer interact. Previous studies have demonstrated that allorecognition in Botryllus is principally controlled by a single Mendelian locus named the fusion/histocompatibility (Fu/HC) locus, with multiple codominantly expressed alleles. However, identification and cloning of this locus has been difficult. We are taking a genomic approach in isolating this locus by creating a detailed genetic linkage map of the 725 Mbp Botryllus genome using DNA polymorphisms (primarily identified as AFLPs) as molecular genetic markers. DNA polymorphisms are identified in inbred laboratory strains of Fu/HC defined Botryllus, and their segregation and linkage is analyzed in a series of defined crosses. Using bulk segregant analysis, we have focused our mapping efforts on the Fu/HC region of the genome, and have generated an initial map which delineates the Fu/HC locus to a 5.5 cM region.

Animals↗