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PubMed1976

Integration and control of circulatory function.

In this chapter we have emphasized especially the intrinsic controls of the circulation, such as the autoregulation mechanism for control of local blood flow, automatic control of cardiac output, long-term control of arterial pressure, long-term control of blood volume, and automatic distribution of fluids between the circulation and the interstitial spaces. The reasons for emphasizing these mechanisms are several: first, many experiments have now shown that the intrinsic mechanisms can provide highly stable long-term control of the circulation. Second, the value of the nervous and hormonal controls have probably been greatly overemphasized in the past. And, third, there are special complexities of the intrinsic controls--such as nonlinearities, delay in responses, and other effects--that have made these difficult to understand; it is probably these difficulties that have led to their underemphasis. However, we have not meant to take from the nervous and hormonal systems their true importance in circulatory control. For instance, intrinsic mechanisms have almost no capability for acute arterial pressure control (only for long-term control), and they have no mechanism for providing the drive necessary to make the animal ingest water and electrolytes. These require the nervous controls. Also, nervous reflexes are important in enhancing the effectiveness of blood volume control and control of cardiac pumping. Among the hormonal mechanisms, the renin-angiotensin system can provide a modest degree of arterial pressure control when the pressure falls below normal by eliciting a vasoconstrictor response in the peripheral blood vessels. However, this system seems to have an even more important renal function, a direct effect on kidneys to cause fluid retention; this in turn increases the body fluid volume and in this way increases the arterial pressure. Finally, the roles of ADH and aldosterone in the control of blood volume have probably been greatly overemphasized. On the other hand, both clinical experience and experimental studies are beginning to demonstrate that the thirst/ADH system is probably by far the most potent mechanism that we have for control of extracellular fluid sodium ion concentration. On the other hand, the aldosterone mechanism seems to be our primary control system for maintaining a normal extracellular fluid concentration of potassium.

Angiotensin II↗

PubMed1962

A spectrum of pharmacological activity in some biologically active peptides.

The actions of bradykinin, angiotensin, oxytocin, vasopressin and substance P have been examined both on isolated smooth muscle preparations and in vivo. It was found that the isolated rat uterus and guinea-pig ileum can be used to distinguish between oxytocin and bradykinin and that the isolated rat colon and hen rectal caecum are almost specific test preparations for substance P. All the peptides were active on peripheral blood vessels, bradykinin, substance P and oxytocin causing vasodilatation and vasopressin and angiotensin vasoconstriction; bradykinin, substance P and angiotensin also caused an increase in capillary permeability in guinea-pigs. Only bradykinin and substance P were active in low concentrations in producing pain when applied to an exposed blister base. These two peptides were also active in causing bronchoconstriction. Oxytocin and vasopressin were the only peptides having milk-ejecting or antidiuretic activity which could be dissociated from cardiovascular effects. The spectrum of activity displayed by these peptides is in agreement with those functions which have been established for vasopressin and oxytocin and with those suggested, but not yet fully accepted, for bradykinin and angiotensin. It also indicates a possible function for substance P based on its vascular and permeability effects.

Angiotensins↗

PubMed2003

[Knowledge of hypertension and blood pressure measurement procedure among students of last year of medical school in Cracow].

The knowledge about hypertension--especially its diagnosis and therapy--among graduates of medical schools, is very important in view of hypertensive epidemics. The aim of this study was to assess the medical graduate's knowledge about recommended technique of blood pressure (BP) measurements, the factors affecting BP measurement value, the WHO/ISH--1999 hypertension diagnostic criteria, and its complications and basic therapy rules. The questionnaire investigating the respondent's knowledge was filled out by 132 medical students of the 6th year Medical College of the Jagiellonian University, in Cracow, from February till June 2000. Only 21.2% of students had good knowledge about BP measurement technique, 70% to 90% of subjects knew hypertension diagnostic criteria, about 30% gave the correct values defined as "high-normal". About 37.1% were aware of complications concerning heart, brain, kidney, eye and peripheral blood vessels. Only 11% knew all drugs recommended by WHO/ISH guidelines, as first-line medication; but 95% were only able to mention at least four of them (diuretics, beta-blockers, ACE-I, Ca-blockers). The students have unsatisfactory levels of knowledge about hypertension. This indicates poor preparation of future physicians in treatment of hypertensive problems.

Blood Pressure↗

PubMed1992

[Cardiovascular effects of noise].

The circulatory response to noise is dominated by a peripheral blood vessels vasoconstriction, of greater magnitude when asleep than awake. Noise of lower frequency seems more able to produce this response. With repetition of the noise, adaptation and tolerance to it quickly appears. Meanwhile prolonged high level noise exposition induces an increasing prevalence of arterial hypertension among industrial workers. This increase is also clearly found in residential communities living near airports. Long-term exposure to noise is a dangerous nuisance, that can lead to an increase in arterial blood pressure and favour coronary artery disease development.

Cardiovascular Diseases↗

PubMed2003

A glance at the von Willebrand factor in dengue virus infection.

To identify the level of von Willebrand factor (vWF) in dengue infection, especially severe DHF, and correlate the increase in vWF with thrombocytopenia, children admitted with dengue fever/DHF were examined for hemoglobin, hematocrit, platelet, and vWF for three consecutive days. Anti-dengue IgM and IgG were determined. Correlations between vWF and thrombocytopenia were analyzed using multivariate analysis. Forty-one patients were eligible for the study; of whom almost three fourths had a secondary infection, as proved serologically. At the beginning of the study, a high level of vWF along with a low platelet count were seen, which seemed to fit the hypothesis that an increase in vWF in the serum will be followed by a decrease in platelets, as a result of the platelet aggregation process in the peripheral blood vessels, predisposed by the immune complex events in DHF. Observations for three consecutive days revealed significant changes of vWF levels (p = 0.000) as well as platelet counts (p = 0.002). However in the context of dengue infections, these changes did not correlate well (p = 0.988). Could there have been a significant correlation if cases were followed for a longer period of time? Being a part of a more comprehensive study, it appeared that in patients with dengue infections, vWF and platelets were not the only factors involved in bleeding, indicating that activation of endothelium is one factor in a multifactorial process.

Adolescent↗

PubMed2004

[T cell immunity analysis in children with obstructive sleep apnea syndrome].

OBJECTIVE: To probe into the possible impact on T cell immunity in children with obstructive sleep apnea syndrome (OSAS). METHOD: Lymphocytes in peripheral blood vessel of children with OSAS vs normal controls were checked by APAAP method and analyzed statistically. RESULT: The comparison with the controls showed that CD3+ had no significant difference (P>0.05), CD4+, CD4+/CD8+ were significantly lower, CD8+ was significantly higher in children with OSAS (P<0.01), and the analysis of the LSaO2 and period of history showed that the lower the LSaO2, and the longer the period of history, the more effect to CD4+, CD8+, CD3+/CD8+ (P<0.05). CONCLUSION: T cell immunity are impaired in children with OSAS.

CD4 Antigens↗

PubMed2004

[Techniques for creating hemodialysis fistulas].

Hemodialysis is the primary method of renal replacement therapy. To conduct hemodialysis therapy, an effective vascular access is necessary. The authors describe basic types of surgically created accesses for hemodialysis and their complications. Peripheral blood vessels are listed by order in which they are used for access creation.

Arteriovenous Shunt, Surgical↗

PubMed2004

Hyperbaric oxygenation and blood lactate clearance: study in sixty male naval cadets.

The research was aimed to study the effects of a 30 minute exposure to 2.5 ATA with 100% O2-inhalation on lactate concentration after muscular fatigue from incremental exercise on a cycle ergometer The subjects were 60 male naval cadets aged 20-23 years whose physical fitness was equivalent to the average athletes. All volunteers participated in the first VO2 max exercise test to obtain their baseline data and randomly assigned into 3 groups of 20. The 3 groups were: Rest recovery group (RR), Oxygen recovery group (OR), and the Hyperbaric oxygenation (HBO2) recovery group (HR). The volunteers took the incremental exercise test (Ordinary Lamp Protocol) on a cycle ergometer to exhaustion, then rested according to the above assigned groups. Blood samples were taken from each volunteer before the experiment, at exhaustion and every 5-minute intervals after the exhaustion for 30 minutes and immediately assayed for lactate concentration. The results showed significant decrease of blood lactate concentration at 15, 20 and 25 minutes intervals after the exhaustion in the HR group compared to the others. It might be initially concluded that HBO2 enhanced the rate of lactate removal from peripheral blood vessels, therefore it shortened the recovery time.

Adult↗

PubMed2005

Protective and anti-fatigue effects of aspirin against heatstroke in rats.

The purpose of this study is to determine whether aspirin can reduce interleukin-1beta(IL-1beta) concentration and exert protective effects against heatstroke. The heatstroke rat model was established through exposing rat to a high ambient temperature (HAT, Ta 41 degrees C, relative humidity 65%) in a simulative HAT chamber to induce heatstroke. Three parts were performed in the present experiment: (1) To determine the effects of pretreatment with aspirin against heatstroke;(2) To prove the effects of specifically reducing inducible nitric oxide synthase (iNOS) against rat heatstroke by iNOS selective prohibitor aminoguanidine (AG);(3) To determine the effects of aspirin against heatstroke and fatigue. In part 1 and 2, Sprague-Dawley rats were randomly assigned to control and aspirin groups or AG groups respectively. Mean arterial blood pressure (MAP), colonic temperature (T(co)), electrocardiograph (ECG) were monitored during heat exposure (HE) and blood samples were taken 0 and 60 min after HE for IL-1betaassay or nitric oxide (NO) assay. In part 3, additional control and aspirin groups of conscious rats were put in a barrel with 41 degrees C water and kept swimming until drowning over 10 s, and then intervals were recorded as survival time. The results from part 1 showed that from 0 to 50 min after HE, MAPs of control group and aspirin group were not significantly different. About 50-60 min after HE, MAPs of both groups were decreased abruptly and MAPs of control group were decreased significantly in comparison with those of aspirin group. T(co) of both groups was increased until to 42 degrees C, without significant difference. Time of heatstroke onset was not significantly different, while survival time was significantly longer in aspirin group than that in control group. Plasma IL-1betaconcentrations in both groups were significantly increased after HE, and the concentration was significantly higher in the control group than that in aspirin group 60 min after HE. In part 3, the survival time was significantly longer in aspirin group than that in control group. In part 2, MAPs of both groups from 0 to 50 min after HE were not significantly different, whereas 55-60 min after HE, MAPs of control group were decreased significantly in comparison with those of AG group;T(co) of both groups was increased after HE until to 42 degrees C, but without significant difference. The time of the heatstroke onset and survival time of AG group were significantly longer than that of control group;the plasma NO concentrations of two groups were significantly higher 60 min after HE than those 0 min after HE, and the plasma NO concentration of control group was significantly higher than that of AG group 60 min after HE. In conclusion, IL-1betamay contribute to heatstroke through inducing iNOS, which attenuates the tone of peripheral blood vessel, and pretreatment with aspirin can provide preventive effects against heatstroke and reinforce the heat and fatigue endurance, which may be associated with inhibition of systemic IL-1betalevels and local iNOS levels.

Journal Article↗

PubMed2005

[Aortic valve replacement for the patient with Osler-Rendu-Weber disease].

Osler Rendu-Weber (O-R W) disease (hereditary haemorrhagic telangiectasia) is characterized by an anormality of the peripheral blood vessels which often causes recurrent epistaxis. We presented a case of aortic valve replacement for the patient with O-R-W disease. A 75-year-old woman diagnosed as O-R-W disease with chest pain and dyspnea was admitted. Preoperative transthoratic echocardiography showed severe aortic valve stenosis (AS) with a pressure gradient (from left ventricle to ascending aorta) of 72.5 mmHg. Urgent aortic valve replacement (AVR) was performed after preoperative hormonal (estrogen-progesterone) therapy, that might be effective for bleeding from vascular ectasia. No hemorrhagic tendency was recognized and the postoperative course was uneventful.

Aged↗

PubMedDate not supplied

[First report of Anaplasma bovis (Donatien and Lestoquard, 1936) Dumler et al. (2001) at micro region of Campos dos Goytacazes, State of Rio de Janeiro, Brazil].

The first report of Anaplasma bovis was pointed out at the micro region of Campos dos Goytacazes, State of Rio de Janeiro, Brazil. Blood smears were done from peripherical blood vessels from 151 calves. Five calves (3.31%) were positive for A. bovis. Symptoms were characterized by debility, fever, pale mucous membranes, and enlargement of prescapular lymph nodes.

Anaplasmosis↗

PubMedDate not supplied

[Urocortin decreases phosphorylation of MYPT1 and increases the myosin phosphatase activity via elevation of the intracellular level of cAMP].

Urocortin, a peptide hormone related to the corticotropin releasing factor, is suggested to be involved in blood pressure regulation by dilating the peripheral blood vessels. In rat tail arteries, urocortin-induced vasodilation is due to a decrease in myofilament Ca2+ sensitivity the mechanism of which is still unclear. In this study, the hypothesis was tested that the decrease in Ca2+ sensitivity in mouse tail arteries results from the activation of myosin light chain phosphatase. The relaxation of KCl-precontracted (42 mM) intact mouse tail arteries by urocortin (1 nM and 10 nM) was significantly inhibited by 1 microM antisauvagine30, a CRF-2 receptor antagonist (p < 0.05, n = 3). The addition of 1 microM KT 5720, an inhibitor of PKA, to intact rat tail arteries did not affect the KCl-induced force but significantly attenuated the urocortin-induced relaxation (n = 5). In alpha-toxin permeabilized mouse tail arteries, urocortin relaxed submaximally activated preparations at constant pCa 6.1 by 37.6 +/- 8.2% (n = 5) as compared to control vessels (n = 5, p < 0.001). The relaxation in permeabilized vessels was inhibited by pre-treatment with 30 microM Rp-8-CPT-cAMPS, an inactive analogue of cAMP. In permeabilized mouse tail arteries, treatment with 100 nM urocortin was associated with dephosphorylation of MLC20(Ser19) and MYPT1(Thr696/Thr850). The effect of urocortin on MYPTI dephosphorylation was completely abolished by 30 M Rp-8-CPT-cAMPS and mimicked by the cAMP analogue Sp-5,6-DCI-cBiMPS. Based on these findings, we propose that the urocortin-induced relaxation is due to a decrease in calcium sensitivity mediated by a cAMP-dependent increase in the activity of MLCP.

Animals↗

PubMed1992

Regional variation in acute vascular homologous tachyphylaxis.

The development of tachyphylaxis or desensitization in a tissue upon repeated application of an agonist is a well-established phenomenon. To investigate the possible basis of vascular homologous tachyphylaxis, vasomotor responses in isolated cerebral and peripheral blood vessels from the cat, dog and rabbit upon repeated application of several agonists were examined using in vitro tissue bath techniques. Tachyphylaxis to vasodilator responses developed to repeated application of vasoactive intestinal polypeptide (VIP) but not to beta adrenergic agonist, forskolin, 8-bromo-cyclic AMP, sodium nitroprusside or 8-bromo-cyclic GMP in feline cerebral arteries. The tachyphylaxis to VIP-induced responses varied among regions and was greatest in the internal carotid artery (ICA), followed by the middle cerebral artery and least in the basilar artery (BA). Cerebral arteries also developed significant tachyphylaxis to constriction induced by repeated applications of neuropeptide Y (NPY), alpha-1 adrenergic agonist, but not to alpha-2 adrenergic agonist, acetylcholine (ACh) or KCl. The tachyphylaxis to constrictions induced by repeated application of neuropeptide Y (NPY) also varied among regions, but was different from that induced by VIP; it was greatest in the BA, followed by the middle cerebral artery and least in the ICA. Similar results were obtained in arteries without endothelial cells. The density of regional innervation of NPY-immunoreactive fibers, which is densest in ICA and sparsest in BA, parallels that of VIP-immunoreactive fibers in these three regions. There is no positive correlation between density of catecholamine fluorescence fibers and degree of tachyphylaxis to noradrenaline-induced constriction in cat ICA, dog saphenous arteries and rabbit ear arteries either.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

[Massive pulmonary brain tissue embolism].

A 20 year old woman with a severe head injury and rapidly increasing brain edema died 46 hours after the accident. There was clinical evidence of protracted shock and disseminated intravascular coagulation. The autopsy revealed a macro-embolization of brain tissue of the lungs with many central and intermediate lung artery branches occluded by cerebral tissue. Preconditions of the brain tissue embolism were a severe fracture of the skull including a traumatic rupture of the right sigmoid sinus, together with a local brain laceration and an extremely elevated intracranial pressure. Fibrin precipitations were prominent at the surfaces of the brain tissue emboli as well as in peripheral blood vessels of the lung; in the systemic circulation, intravascular coagulation was much less pronounced.

Accidents, Traffic↗

PubMed1990

[Emergency vascular access in patients with renal failure. Apropos of 32 implantations of permcath].

Central venous catheters allow for the most rapid hemodialysis procedure with sparing of peripheral blood vessels. 32 flexible, double-lumen "permcath" catheters were implanted to 27 patients over a period spanning 42 months (February 86-August 89). Catheter placement was definitive in 2 cases while another 30 provided previsory intravenous access for plasmapheresis (25 cases), acute renal insufficiency (7 cases), and chronic renal failure (17 cases). The mean utilization time per patient was 10.7 +/- 8.01 (SE) weeks. As respects chronic renal failure, this provided a time-opportunity for prospective maturation of conventional venous routes of access or transplantation. Permcath thrombosis occurred in 6 instances (18.75%), 5 times unremittingly (15.4%). Infection occurred in 6 patients (18.75%), leading to ablation of the permcath only once. Thus, permcath ensures safe, effective access for hemodialysis and enables maturation of a conventional venous cutdown. It may be used directly as a permanent vascular approach in case of limited life expectancy or of an extremely precarious vascular bed.

Acute Kidney Injury↗

PubMed1989

The synthesis and effects of eicosanoids in avascular ocular tissues.

The cornea and the lens have some common features: both organs are avascular, have a high protein concentration, and are transparent, having relatively high indices of refraction. Because experiments done by various investigators have differed with respect to tissue preparation, incubation time, the amount of AA used as substrate, the cofactors used, and so forth, it is difficult to make a direct comparison of the ability of the lens and the cornea to synthesize eicosanoids. Nevertheless, based on the preceding review, we can conclude that the cornea has a higher capacity than does the lens to produce PGs and lipoxygenase products. One important difference between these two tissues is that the cornea is innervated, whereas the lens is not. This raises the question of the possible influence of neuronal elements on the synthesis and effects of eicosanoids. There is substantial evidence that neuronal mechanisms play a role in various aspects of corneal physiology. In rabbits, there is decreased ability for corneal wound healing after surgical interruption of the trigeminal ganglion (Beuerman and Schimmelpfennig, 1980). The cornea contains beta-adrenergic receptors (Neufeld et al., 1978) and cAMP mediates the initial events in the healing process in the corneal epithelium (Jumblatt et al., 1980). PGE2 is an activator of this pathway (Schaeffer et al., 1982). However, it is not known how neuronal mechanisms may influence the synthesis of PGs in the cornea. It must also be kept in mind that the responses of the cornea to inflammation involve the interplay of several mediators, some of which come from the corneal cells and others from recruited inflammatory cells. The lens is also avascular and in contrast to the cornea, which has some peripheral blood vessels, the lens remains avascular even after injury. When it is injured, the lens, in the absence of a blood supply, responds instead to the composition of the aqueous humor. Secondary aqueous humor formed after ocular trauma or paracentesis has been shown to trigger mitosis of the lens cells (Reddan et al., 1979). It has also been clearly demonstrated that injury to the eye produces increased release of PGs in the aqueous humor (Unger, 1989). There is also evidence that some PGs, mainly PGF2 alpha, can act as mitogens in some cells (Jimenez de Asua et al, 1983). Therefore, the low capacity of the lens to synthesize PGs can be compensated for by the presence of these eicosanoids in the aqueous humor.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

[Effect of a single mild infrared A hyperthermia on body temperature, heart rate, blood pressure and blood viscosity in healthy probands and patients with stage I and II arterial hypertension].

Report on mild and single whole body-irradiations with near infrared (IRA). The central body temperature went up to 38.5 degrees C in 9 healthy subjects and 9 patients known as having essential arterial hypertension of the stages I or II. In case of hypertensive patients a single exposure decreased significantly both arterial and venous blood pressure as well as the resulting mean arterial blood pressure. This beneficial effect lasted for at least 24 hours. Besides that, improvement of peripheral hemodynamics and plasma viscosity also was proven. Obviously, improved peripheral hemodynamics is linked to that blood pressure lowering effect which happens due to dilatation of peripheral blood vessels.

Adult↗

PubMed1985

Bordetella heat-labile toxin: further purification, characterization and mode of action.

The heat-labile toxin (HTL) was purified from sonic extracts of Bordetella bronchiseptica and Bordetella pertussis cells by a series of hydrophobic interactions, density gradient centrifugation, gel filtration, isoelectric precipitation, and isoelectric focusing. A 114-fold purification was regularly obtained with a yield of 31%. A dose of 0.75 ng was dermonecrotizing in guinea pigs. HLT is a simple protein (pI 6.9) with a molecular weight by gel filtration of 102,000 which consists of two polypeptides of 30,000 and 24,000 molecular weight. Amino acid analysis showed 15 common amino acids and the absence of methionine. The dermonecrotizing activity was inactivated at 56 degrees C, and at above pH 10 or below pH 5. Effects of various ions, detergents, enzymes and other chemical agents on HLT were determined. When instilled on the surgically exposed peripheral blood vessels of guinea pigs or suckling mice, HLT induced vasoconstriction within 15 min resulting in the decrease of blood flow, followed by manifestations of ischemia, diapedesis and petechial hemorrhage during the following 5 h. HLT activity on arterioles was unaffected by adrenergic or cholinergic blockades. Biochemically, HLT significantly inhibited in vitro the activity of Na+ - K+ ATPase prepared from rat kidney. A possible mechanism by which HLT induces dermohemorrhagic necrosis and splenic atrophy, is discussed.

Animals↗