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Biomedical subjects

R Urban

Publications and source records attributed to R Urban.

At least 19 recordsLinked to original sources

[Antepartum amniotic fluid index and pregnancy outcome].

Our purpose was to evaluate prognostic value of antepartum amniotic fluid index (AFI) on fetal and newborn outcome, because oligohydramnion is associated with increased risk of fetal and newborn distress. Perinatal outcome was defined by 1' and 5' Apgar score, intrapartum fetal heart rate (FHR), blood gas, acid-base status in umbilical artery, mode of delivery and meconium-stained amniotic fluid. Data was analysed with CSS Statistica for Windows package by test t for independent samples and chi 2. Prospective observations was conducted with 84 singleton pregnancies complicated by oligohydramnion (AFI < or = 5 cm). A 336 pregnant women, with normal amniotic fluid index and no complicated pregnancy, was considered as controls. No increased operative delivery and meconium-stained amniotic fluid rate was noted. There was no significant effects AFI on blood gases in umbilical artery and Apgar score. Oligohydramnion was associated with increased risk of fetal acidosis (pH < 7.16) (p = 0.009) and abnormalities of FHR (variable decelerations) (p = 0.004). Reduced AFI had poor predictive value of fetal acidosis and newborn depression positive predictive value (8-13%). Summarizing the results, our investigation showed that amniotic fluid index is only one point in the prognosis of perinatal outcome.

Adult

Role of I1 imidazoline receptors in the sympathoinhibition produced by intracisternally administered rilmenidine and moxonidine.

The role of alpha 2-adrenoceptors and I1 imidazoline receptors in the cardiovascular effects of rilmenidine (CAS 54187-04-1), moxonidine (CAS 75438-57-2) and guanabenz (CAS 23256-50-0) was studied in conscious rabbits. In radioligand binding studies, rilmenidine and moxonidine are selective for I1 imidazoline receptors (vs. alpha 2-adrenoceptors) and guanabenz is selective for alpha 2-adrenoceptors (vs. I1 imidazoline receptors). Efaroxan (CAS 89197-00-2; selective for I1 imidazoline receptors) and yohimbine (CAS 65-19-0; selective for alpha 2-adrenoceptors) were used as antagonists. All drugs were injected into the cisterna magna. Guanabenz (1, 3, 10 and 30 micrograms kg-1), rilmenidine (1, 3, 10 and 30 micrograms kg-1) and moxonidine (0.03, 0.1, 0.3 and 1 microgram kg-1) dose-dependently lowered blood pressure, heart rate and the plasma concentration of noradrenaline. In the antagonism experiments, guanabenz (10 micrograms kg-1), rilmenidine (10 micrograms kg-1) and moxonidine (0.3 micrograms kg-1) were administered first; they caused equal hypotension. Injection of the agonists was followed by injection of efaroxan (0.3-1 microgram kg-1) or yohimbine (0.1-0.3 micrograms kg-1). Efaroxan and yohimbine were equieffective at antagonizing the effects of guanabenz. In contrast, efaroxan was more effective than yohimbine at antagonizing the effects of rilmenidine and moxonidine. The results show that intracisternally administered guanabenz, rilmenidine and moxonidine cause sympathoinhibition. alpha 2-Adrenoceptors are responsible for the sympathoinhibition produced by guanabenz. In contrast, I1 imidazoline receptors are involved in the sympathoinhibition caused by rilmenidine and moxonidine.

Adrenergic alpha-2 Receptor Antagonists

Involvement of peripheral presynaptic inhibition in the reduction of sympathetic tone by moxonidine, rilmenidine and UK 14304.

We studied the possibility that presynaptic inhibition of transmitter release from postganglionic sympathetic neurons contributes to the overall reduction of sympathetic tone produced by moxonidine, rilmenidine and 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline tartrate (UK 14304). In pithed rabbits without electric stimulation, moxonidine, rilmenidine and UK 14304 caused a long-lasting, > 10 min, increase in arterial pressure. Heart rate was not changed. In pithed rabbits in which sympathetic tone was created by electric stimulation through the pithing rod (2 Hz), the same doses of moxonidine, rilmenidine and UK 14304 caused only a brief, < 10 min, blood pressure rise. Heart rate was decreased, as were the plasma concentrations of noradrenaline and adrenaline. Dose-response curves for the effects on the plasma noradrenaline concentration (stimulated pithed rabbits) were compared with previously obtained dose-response curves for depression of renal sympathetic nerve activity (conscious rabbits). For each drug, the curve describing peripheral presynaptic inhibition and the curve describing central sympathoinhibition were very similar. Both the power and the dose dependence of the peripheral inhibitory effect support its contribution to the overall decrease in sympathetic tone produced by clonidine-like drugs in intact animals. The peripheral effect in all likelihood consists in activation of presynaptic alpha 2-autoreceptors. The agreement of the dose-response curves for the peripheral and for the central effect supports the view that the central effect, like the peripheral one, is mediated through alpha 2-adrenoceptors.

Adrenergic alpha-2 Receptor Agonists

Involvement of alpha 2-adrenoceptors in the cardiovascular effects of moxonidine.

The central sympathoinhibition caused by moxonidine has been explained by activation of alpha 2-adrenoceptors on the one hand, and by an action at imidazoline I1 receptors on the other hand. In order to examine these possibilities, effects of moxonidine were compared with those of 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline (UK 14304), an alpha 2-adrenoceptor agonist with very low affinity for I1 receptors, in conscious rabbits. The interaction with yohimbine, an alpha 2-adrenoceptor antagonist with very low affinity for imidazoline I1 receptors, was also studied. Moxonidine 3-100 micrograms kg-1 and UK 14304 1-30 micrograms kg-1 i.v. elicited similar effects: they decreased arterial blood pressure after a transient increase, decreased renal sympathetic nerve activity (recorded with chronically implanted electrodes), decreased heart rate and decreased the plasma noradrenaline concentration. Yohimbine given i.v. antagonized the effects of moxonidine and of UK 14304 in a similar manner. Yohimbine injected into the cisterna magna (i.c.) prevented the hypotension but did not change the decrease in plasma noradrenaline and heart rate, again in the case of both moxonidine and UK 14304. The agreement of the effect patterns of moxonidine and UK 14304, and the similar antagonism of yohimbine against either drug, demonstrate involvement of alpha 2-adrenoceptors in their central sympathoinhibitory action. The resistance of the bradycardia and the plasma noradrenaline fall against yohimbine i.c. indicates a contribution of presynaptic alpha 2-adrenergic inhibition of transmitter release from postganglionic sympathetic neurons to the overall reduction of sympathetic tone.

Adrenergic alpha-2 Receptor Agonists

Mechanism of sympathoinhibition by imidazolines.

The aim of the present study is to characterize the cardiovascular effects of rilmenidine and moxonidine, two recently developed centrally acting antihypertensive drugs. Rilmenidine and moxonidine are alpha 2-adrenoceptor agonists and, in addition, possess affinity for imidazoline (I1)-receptors. To determine if alpha 2- or I1-receptors are involved in sympathoinhibition, rilmenidine and moxonidine were compared with UK 14304, an alpha 2-agonist devoid of affinity for I1-receptors, and antagonism by the "pure" alpha 2-adrenoceptor antagonists yohimbine, SK&F86466, and RX821002 was studied. When injected intravenously into conscious rabbits, rilmenidine and moxonidine, on the one hand, and UK 14304, on the other, elicited a similar pattern of effects. Thus, transient hypertension was followed by long-lasting hypotension accompanied by a decrease in heart rate, renal sympathetic nerve firing rate, and plasma norepinephrine concentration. The effects of rilmenidine, moxonidine, and UK 14304 were antagonized by intravenously administered yohimbine, SK&F86466, and RX821002. The effects of moxonidine and UK 14304 were also prevented by yohimbine injected into the cisterna magna. Altogether, the degree of antagonism of the effects of rilmenidine and moxonidine did not differ from the degree of antagonism of the effects of UK 14304. Rilmenidine, moxonidine, and UK 14304 were also given to pithed rabbits in which a constant sympathetic tone was maintained by electrical stimulation of the sympathetic nerves. At doses that caused sympathoinhibition in conscious rabbits, they lowered the plasma norepinephrine concentration markedly. Our experiments show by direct measurement of sympathetic nerve activity and plasma norepepinephrine concentration that rilmenidine, moxonidine, and UK 14304 cause sympathoinhibition. As a consequence, blood pressure and heart rate decrease. The simplest interpretation of the blockade of central sympathoinhibition by the selective alpha 2-adrenoceptor antagonists is that rilmenidine, moxonidine, and UK 14304 primarily activated alpha 2-adrenoceptors. The decrease in plasma norepinephrine in pithed rabbits indicates peripheral presynaptic alpha 2-adrenoceptor-mediated inhibition of norepinephrine release per action potential from postganglionic sympathetic axons and suggests a contribution of this mechanism to the overall reduction in sympathetic tone.

Adrenergic alpha-2 Receptor Agonists

Cardiovascular effects of agmatine, a "clonidine-displacing substance", in conscious rabbits.

Agmatine has been identified as a "clonidine-displacing substance" in extracts from bovine brain. We studied its effect on cardiovascular regulation and the role played in this effect by alpha 2-adrenoceptors. In conscious rabbits, agmatine 10 micrograms kg-1 injected intracisternally (i.c.) caused no change, whereas agmatine 30, 100 and 300 micrograms kg-1 i.c. increased renal sympathetic nerve firing, the plasma concentration of noradrenaline and adrenaline and arterial blood pressure. Heart rate tended to be decreased. Yohimbine 1.5 micrograms kg-1 i.c. caused no change, whereas yohimbine 5, 15 and 50 micrograms kg-1 increased renal sympathetic nerve activity, the plasma concentration of noradrenaline and adrenaline, blood pressure and heart rate. In rabbit brain cortex slices preincubated with [3H]-noradrenaline, agmatine 1 to 100 microM did not modify the electrically evoked overflow of tritium (either 4 pulses at 100 Hz or 36 pulses at 3 Hz). The evoked overflow was reduced by 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline (UK 14304) 0.03 to 30 nM (4 pulses at 100 Hz), and this inhibition was not affected by agmatine 10 and 100 microM. Agmatine did not change the basal efflux of tritium. The results show that agmatine, like yohimbine, causes central sympathoexcitation when given i.c., but agmatine differs from yohimbine in that it does not increase heart rate. Agmatine acts neither as an agonist nor as an antagonist at the alpha 2-autoreceptors in rabbit brain cortex. alpha 2-Adrenoceptors, therefore, are probably not involved in its cardiovascular effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials

[The incidence, age dependence and sex distribution of the calcaneal spur. An analysis of its x-ray morphology in 1027 patients of the central European population].

In 1027 lateral radiograms of the ankle in a Caucasian population, 161 plantar and/or dorsal calcaneal spurs (15.7%) were diagnosed. Plantar spurs were more common than dorsal spurs (11.2 and 9.3% respectively). Prevalence of both spurs increases considerably with the rising age. Dorsal spurs appear slightly earlier than plantar spurs. The spur frequencies are similar in left and right feet. The plantar spurs were significantly (p < 0.0001) more common in women than in men in general, while dorsal spurs were more frequent in men than in women up to the age of 70. The previously reported higher frequencies of plantar and dorsal calcaneal spurs in women than in men are probably a result of a disproportionally higher number of women in higher age in the groups studied. In forensic medicine, calcaneal spurs provide evidence for identity and age of unknown corpses, and to certain extend their profession, physical activities and constitution during life.

Adolescent

[1H-MR spectroscopic imaging: an approach to evaluating alcohol breakdown in the brain].

The local alcohol concentration in the human brain was determined in 10 cases using MR spectroscopic imaging. Therefore 7 subjects with an average blood alcohol concentration of 0.8/000 were examined after oral intake of alcoholic beverages. Varying alcohol concentration was found intracranially which was recorded spectroscopically w.r.t. time. Relatively high ethanol concentrations were determined in the cerebellum as well as in the ventricular system. Contrary to this, lower concentrations were found in the regions of grey and white matter.

Adult

Is the sympathoinhibitory effect of rilmenidine mediated by alpha-2 adrenoceptors or imidazoline receptors?

The involvement of alpha-2 adrenoceptors or imidazoline-1 receptors in the sympathoinhibitory effect of rilmenidine was investigated in conscious rabbits. Dose-response curves were determined for the effects of rilmenidine as well as of the alpha-2 selective agonist UK 14304 [5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline] on blood pressure, heart rate, renal postganglionic sympathetic nerve activity and the plasma norepinephrine concentration. The interaction with the alpha-2 selective antagonist SK&F 86466 [6-chloro-N-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine] also was studied. Rilmenidine (30-1000 micrograms kg-1 i.v.) and UK 14304 (1-30 micrograms kg-1 i.v.) elicited the same pattern of changes: transient hypertension followed by prolonged hypotension, bradycardia, a depression of sympathetic nerve firing and a fall in the plasma norepinephrine concentration. The ED50 values for these effects increased in the same order for both drugs: plasma norepinephrine fall < hypotension < depression of sympathetic nerve firing << bradycardia. Pretreatment with SK&F 86466 (3 mg kg-1 i.v. followed by an infusion of 1 mg kg-1 hr-1) altered the dose-response curves of rilmenidine and UK 14304 in a qualitatively and quantitatively almost identical manner; a rightward shift of the hypotensive, sympathoinhibitory and plasma norepinephrine level dose-response curves but no change of the dose-response curve for heart rate. The similarity of the effects of rilmenidine and UK 14304, and the almost identical antagonism of SK&F 86466 against either drug, argue against different sites of action of rilmenidine and UK 14304.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Agonists

Sympathoinhibition by rilmenidine in conscious rabbits: involvement of alpha 2-adrenoceptors.

Cardiovascular and sympathetic nervous system effects of the mixed alpha 2-adrenoceptor and imidazoline receptor agonist rilmenidine were studied in conscious rabbits chronically instrumented for the recording of the firing rate of renal sympathetic fibers. Separate experiments were carried out on pithed rabbits with electrically stimulated (2 Hz) sympathetic outflow. Drugs were administered intravenously in a cumulative manner. In conscious rabbits, rilmenidine 0.1, 0.3 and 1.0 mg kg-1 dose-dependently lowered blood pressure, renal sympathetic nerve activity, heart rate and the plasma concentration of noradrenaline and adrenaline. The effect on blood pressure and plasma catecholamines was maximal after 0.3 mg kg-1 whereas heart rate and renal sympathetic nerve activity decreased further after rilmenidine 1.0 mg kg-1. Yohimbine 0.1 and 0.5 mg kg-1, when injected subsequently, attenuated and at the higher dose abolished all effects of rilmenidine. The effects of rilmenidine were also antagonized by the alpha 2-adrenoceptor antagonist 2-(2,3-dihydro-2-methoxy-1,4-benzodioxin-2-yl)-4,5-dihydro-1H-imid azole HCl (RX821002; 0.1 and 0.5 mg kg-1). Yohimbine 0.1 and 0.5 mg kg-1 did not attenuate or attenuated only slightly the decrease of heart rate and renal sympathetic nerve activity produced by infusion of vasopressin. In pithed rabbits with electrically-stimulated sympathetic outflow, yohimbine 0.1 submaximally and yohimbine 0.5 mg kg-1 maximally increased the plasma noradrenaline concentration. The experiments show by direct measurement of sympathetic nerve firing and plasma catecholamines that rilmenidine causes sympathoinhibition in conscious rabbits, presumably through central sites of action.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-2 Receptor Antagonists

Metal release from titanium fixtures during placement in the mandible: an experimental study.

Titanium screw taps and titanium fixtures were investigated by SEM before and after experimental use. Peri-implant bone surfaces were examined immediately after surgery and 5 months after implantation by SEM using the SE mode, backscattered electron imaging, and EDX analysis to detect titanium contamination of the bone specimens. The Ti content of the livers, kidneys, and lungs of six Göttingen minipigs, which had received two screw implants each, was determined using flameless atomic absorption spectroscopy and compared to a control group with no implants. Results showed that Ti particles were abraded and deposited on the bone surface during the preparation of implant beds. Five months after placement, particles were no longer observed on the bone surface next to the implants. Determination of the Ti concentration of the inner organs showed that the lungs contained the highest amount of titanium. The Ti content of the kidneys and livers was much lower. All values differed significantly from those of the control group (P < .01).

Alveolar Process

[Trabeculotomy and goniotomy in congenital glaucoma].

The authors evaluated efficiency of antiglaucomatous surgery in 73 eyes of 50 children, staying under clinical control in the years 1969-1991. It was showed that after trabeculectomy, as the primary procedure, intraocular pressure was normalized much more often (40.9%) than after goniotomy (20.2%). In cases operated many times using different technics, more effective was goniotomy. Better visual acuity was found in cases with intraocular pressure well controlled after one surgical procedure. The most common complications connected with surgery were discussed.

Child

Collaborative efforts: developing clinical experiences for nursing students in public sector settings.

In the present paper we described the Nurse Academic Collaboration Task Force, which was formed in 1989 by the Texas Mental Health and Mental Retardation (TXMHMR) Commissioner in order to facilitate linkages between academia and state facilities. These efforts have led to increased academic collaboration and linkage with facilities. The task force has identified areas of practice opportunities for all levels of student education programs as well as barriers to collaboration. Collaborative strategies may also lead to better nurse recruitment efforts by TXMHMR facilities. Finally, these educational experiences should prepare nurses in varied settings to provide care for individuals with mental retardation.

Communication Barriers

Phase I trial of ImuVert (natural membrane vesicles associated with ribosomes) in patients with advanced cancer.

ImuVert, a new biological response modifier, was evaluated for toxicity and potential efficacy in patients with advanced cancer. This agent consists of sized, labile, natural membrane vesicles associated with ribosomes derived from Serratia marcescens. ImuVert induces enhanced in vitro macrophage and natural-killer-cell-mediated cytotoxicity, and has demonstrated antitumor activity in palpable animal tumor systems. A group of 39 patients with a variety of tumors, 25 men, 14 women, with a mean performance status (Karnofsky) of 80% and median age of 57 years were entered into this trial. ImuVert was administered subcutaneously weekly for a minimum of 3 weeks. A total of 183 treatments were evaluated. Flu-like systemic toxicities, including fever, chills, nausea, vomiting, diarrhea and hypotension were observed. Erythema, induration and tenderness developed at the injection sites. Myelosuppression, thrombocytopenia, anaphylaxis, rental and hepatic toxicities did not occur. All symptoms resolved within 24 h. Two patients with nodular lymphoma achieved a partial response and two minor responses were seen in patients with glioblastoma and melanoma. On the basis of ImuVert's biological activity, and tolerable toxicity it warrants further clinical investigation.

Adult

[Homicide simulating electrocution suicide by spinal anesthesia].

A married woman was found dead with indications of suicide by electricity (household-voltage). On coroner's inquest (typical electric lesions at the wrist) and the result of police investigation, there was no indication of third party involvement. The cadaver war firstly released to burial, but on account of indication of conflicts between the married couple, a forensic autopsy was arranged. The most important pathological finding was a fresh puncture between L3/L4. On toxicological investigation, toxic concentrations of the local anaesthetic prilocaine were found in liquor and organs. Cause of death was central respiratory- and circulatory depression. The husband, an anaesthesist, blamed he was assisting the suicide of his wife at her request. He was found guilty by reasons of manslaughter but not for murder.

Adult