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At least 19 recordsLinked to original sources
PubMed1975

[Effects of combination alfaxalone and alfadolone, anesthetic derivatives of pregnanedione, on cerebral hemodynamics in cats].

Intravenous injection of CT 1341 (a mixture of alphaxalone and alphadolone dissolved in cremophor el) induced a decrease in cerebral blood flow (CBF) measured by 133Xe clearance in cats with artificial respiration (the mean reduction in CBF was 2 ml/100 g/mn for 1,2 mg/kg or CT 1341. So, CBF was decreased by 22% when CT 1341 (7,2 mg/kg) was intravenously injected, (mean Pa CO2 equals 30 mm Hg). Changes in CBF following CT 1341 intravenous injection seems to be caused by cerebral vascular constriction evidenced by the direct observation of pial vessels. Following intravenous injection of CT 1341 (from 7, 2 mg/kg to 19,2 mg/kg), the cerebrovascular reactivity to hypercapnia or hypocapnia was not affected, but autoregulation of cerebral blood flow was transiently abolished. In animals with free respiration, CBF was increased in relation with the elevation in Pa CO2 caused by the depression of respiration.

Alfaxalone Alfadolone Mixture↗
PubMed1978

The binding of 5 alpha-pregnane-3,20-dione by cytosol and nuclear preparations of guinea pig uterus.

We compared the binding characteristics of [3H]progesterone and 5 alpha-[3H]pregnanedione in cytosol and nuclear preparations of ovariectomized, estrogen-treated guinea pig uterus. There were similarities as well as differences in binding behavior. [3H]Progesterone and 5 alpha-[3H]pregnanedione were bound in cytosol with approximately the same apparent association constants and concentrations of binding sites. When centrifuged on sucrose gradients in 5 mM phosphate buffer, binding peaks with sedimentation coefficients of 7S were found with both. 5 alpha-[3H]Pregnanedione was bound by uterine nuclei and, like [3H]progesterone, required temperature-activated cytosol of estrogen-stimulated uterus. A series of unlabeled steroids had similar relative abilities to displace both [3H]progesterone and 5 alpha-[3H]pregnanedione from receptor complexes in cytosol or nuclei. When cytosol was incubated with increasing concentrations of [3H]progesterone or 5 alpha-[3H]pregnanedione the amount of 5 alpha-[3H]pregnanedione bound exceeded the amount of [3H]progesterone bound at steroid concentrations above 5 x 10(-9) M. This suggested that 5 alpha-pregnanedione was bound by additional components of the cytosol and the suggestion was strengthened by sucrose gradient analysis. At greater than saturating-steroid concentrations, the partition between 7S and 4 S binding proteins was different. [3H]Progesterone bound to 7S binding proteins in preference to 4S binders, whereas 5 alpha-pregnanedione showed relatively more 4S binding.

Animals↗
PubMed1979

Effects of progestins on the progesterone receptor in guinea pig uterus.

We examined the effects of progesterone and some synthetic progestins and other steroids on the physical properties of the progesterone receptor of guinea pig uterine cytosol and on the binding of the receptor by nuclei. Progestational potency seemed to correlate with the ability to keep the receptor in the 7S form and to prevent dissociation into smaller subunits. The rate of activation prior to nuclear binding was slower with steroids of increasing progestational activity. Therefore activation in vitro may be unrelated to biological activity. Concentration of the cytosol led to a decrease in the equilibrium association constant. The extent of the decrease was less with progesterone than with its metabolite, 5 alpha-pregnanedione. When cytosol and nuclei were incubated in the absence of ligand measureable progesterone receptor was bound by the nuclei. The uncomplexed nuclear receptor bound [3H]-progesterone of [3H]-R5020 rapidly at 0 degrees, but progesterone-receptor complexes exchanged [3H]-progestin slowly at 0 degrees. Progesterone increased the amount of nuclear receptor at concentrations of 10(-9) and 10(-8)M, but decreased binding at higher concentrations. 5 alpha-Pregnanedione had the same effect as progesterone, but other metabolites of progesterone that had little affinity for the 7S progesterone receptor in cytosol had no effect on nuclear binding at any concentration. Glucocorticoids, testosterone and estradiol-17 beta increased the nuclear binding of the progesterone receptor when present at concentration of 10(-8)M and greater.

Animals↗
PubMed1977

Ovarian steroid effects on gonadotrophin output, and on the incorporation of 35S from methionine into protein of discrete brain areas and the anterior pituitary.

The effects of various ovarian hormones administered on the morning of pro-oestrus on gonadotrophin levels and the incorporation of 35S from methionine into protein of discrete areas of the brain and the anterior pituitary were investigated at 15.00 h of the same day in female rats. The hormones which were investigated in this study could be divided in general into two groups according to their actions. The first group, consisting of oestradiol-17 beta and progesterone, tended to advance the pre-ovulatory surge of luteinizing hormone (LH) by 3-6 h from 18.00-21.00 h, together with the peaks of [35S]incorporation in the median eminence area and the anterior pituitary which normally accompany the LH surge. The second group, consisting of the LH-stimulated reduced progesterone metabolites, 5 alpha-pregnane-3,20-dione (pregnanedione) and 20 alpha-hydroxy-pregn-4-en-3-one (dihydroprogesterone), tended to inhibit serum gonadotrophin levels as well as inhibiting the pro-oestrous increase of [35S]incorporation in the median eminence area and in the amygdala, but not in the preoptic area and the anterior pituitary. On the afternoon of pro-oestrus in intact animals, luteinizing hormone-releasing hormone or LH administration had the same effect on [35Si1incorporation in the brain as did the progesterone metabolites, though this effect was not observed if the animals had been ovariectomized a few hours beforehand. It is suggested that certain ovarian hormones are involved in the neural events which induce the pre-ovulatory LH surge, while others are associated with neural events which terminate the stimulus for the LH surge.

20-alpha-Dihydroprogesterone↗
PubMed1976

Changes in multiunit activity and EEG induced by the administration of natural progestins to flaxedil immobilized cats.

The effects of progesterone (P) and 7 of its metabolites on the EEG and multiunit activity (MUA) of various limbic structures were studied in flaxedil immobilized cats. Most progestins inhibited the MUA of the mesencephalic reticular formation, hippocampus and hypothalamus and induced cortical EEG synchronization. MUA changes in the mesencephalic reticular formation frequently preceded EEG synchronization. Progestins reduced in the 5 beta postition (pregnanolone, epipregnanolone and pregnanedion) inhibited neuronal discharge and synchronized EEG activity with shorter latencies and in lower doses than those reduced in the 5 alpha position (allopregnanolone and allopregnanedion). Progestins having the delta 4,3-keto structure (P, 20 alpha-hydroxy pregnenone, 20 beta-hydroxy pregnenone) induced electrophysiological changes with prolonged latencies and in doses significantly higher than ring A reduced progestins. Administration of epipregnanolone to "cerveau isole" preparations depressed neuronal firing in those structures located rostral to the level of the brain stem transection (hypothalamus, hippocampus), but failed to increase the already synchronized cortical activity. These results suggest that: a, ring A reduction increases the capacity of P and other delta 4,3-keto progestins to inhibit neuronal discharge in certain brain areas and b, changes in neuronal firing induced by progestins are not necessarily mediated through the cat brain stem reticular formation.

Animals↗
PubMed1979

Cyclical changes in the carbohydrate composition of dog endometrium.

In the first part of prooestrus glucuronic acid could not be detected, but small amounts of glucose, fructose, inositol and sorbitol were found. When progesterone was formed a small amount of glucuronic acid could be observed and sorbitol had disappeared. During the first weeks of metoestrus the amounts of fructose and glucose increased gradually, but those of glucuronic acid remained low. When more progesterone and pregnanedione were found in the endometrium the amounts of glucuronic acid began to increase and the highest values were reached in anoestrus. During the last days of anoestrus a sudden change in the carbohydrate composition of the endometrium occurred: glucuronic acid and fructose could no longer be detected, the amounts of glucose and inositol decreased and sorbitol was found. These findings show that next to the cyclical ovarian events, there is a cyclical change in te carbohydrate composition of dog endometrium.

Animals↗
PubMed1978

Accidental over-dose of alfathesin under general anaesthesia: case report.

Under general anaesthesia, 35 ml of alfathesin was accidentally injected intravenously. There was no change in the pulse rate and blood pressure. However, two hours later, at the end of the operation, the rectal temperature was 31 degrees C. There were no long-lasting effects of the overdose.

Adult↗
PubMed1978

A comparative assessment of alfathesin for use in outpatient anaesthesia.

Alfathesin and thiopentone were compared in a double blind study where each drug was given by intravenous infusion supplemented with fentanyl and nitrous oxide, in 54 healthy female patients under-going therapeutic abortion. The two drugs were similar in terms of changes in cardiorespiratory variables, side effects, clinical efficacy, and patient acceptability. Alfathesin produced a significantly more rapid recovery from anaesthesia, without the high incidence of dreams found with thiopentone in this study. Alfathesin would seem to be the preferable drug for use in outpatients undergoing minor surgical operations.

Abortion, Therapeutic↗
PubMed1977

Malignant hyperthermia and althesin.

General anaesthesia with Althesin was administered on two occasions to a patient who was identified as susceptible to malignant hyperthermia, in whom there was identified familial subclinical myopathy and once in another patient suffering from arthrogryposis multiplex congenita with a history of fever associated with two previous anaesthetics. In the first patient halothane was administered by accident in association with the Althesin, but no hyperpyrexia occurred. In the second instance nitrous oxide-oxygen and halothane were associated purposely with Althesin. In none of these cases was there any rise in temperature, muscle rigor or elevation of the serum CPK level. This experience corroborates the experimental evidence of Hall, et al.10 and Harrison, who reported that Althesin prevented the onset of hyperthermia, and the clinical reports of Page and Judelman. Althesin can be assumed to be an effective anaesthetic for malignant hyperthermia susceptible patients.

Alfaxalone Alfadolone Mixture↗
PubMed1978

The influence of fentanyl on an alfathesin infusion technique.

The effects of fentanyl (1 microgram/kg) supplementing an alfathesin infusion technique were assessed in a double blind study in 53 healthy unpremedicated female patients undergoing therapeutic abortion as outpatients. The addition of fentanyl reduced the tachycardia, tachypnoea and hyperventilation seen in those patients receiving alfathesin alone, without unduly prolonging recovery time. Two patients receiving alfathesin alone developed marked coughing or laryngospasm. Fentanyl would seem to be a desirable addition to an alfathesin infusion technique in unpremedicated patients presenting for outpatient anaesthesia.

Adult↗
PubMed1976

Alphathesin, a new steroid anaesthetic agent.

This is a study of 220 patients, most of them out-patients, who were anaesthetized with Alphatehsin. Although the use of Alphathesin has not been discussed in depth, one can say that it is not a substitute for other intravenous anaesthetics available at the present time. Alphathesin, however, deserves further study as it may be able to supply new solutions to new problems which are encountered daily in our specialty, particularly in the field of out-patient surgery.

Adolescent↗
PubMed1976

The effects of althesin and thiopentone on sympathetic and baroreflex activity.

In decerebrate rabbits which were mechanically ventilated, both Althesin and thiopentone depressed preganglionic sympathetic activity and arterial pressure. Conduction through central baroreceptor pathways, tested by depressor nerve stimulation, showed a selective inhibition of the heart rate response by both agents. Effects were similar with Althesin injection in animals which were lightly anaesthetized with pentobarbitone. Depression of the arterial pressure and sympathetic components of the baroreceptor reflex was apparent only with high doses.

Alfaxalone Alfadolone Mixture↗
PubMed1977

Effects of althesin, etomidate and fentanyl on haemodynamics and myocardial oxygen consumption in man.

The acute effects of althesin, etomidate and fentanyl upon haemodynamics, myocardial contractility and oxygen comsumption of the heart were studied in healthy premedicated patients (n = 15) lightly anaesthetized with N2O-O2 (ratio 2:1), 0.3 volumes per cent of halothane and isoflurane respectively. All individuals were ventilated at a normal level. The patients (n = 9) in the halothane group received etomidate 0.3 mg/kg and 20 minutes later althesin 0.075 ml/kg intravenously. In a second group of 6 patients on isoflurane fentanyl 0.01 mg/kg was given. Etomidate did not affect the cardiovascular system significantly. While the decrease in blood pressure after althesin (24 per cent) was the result of a reduction in total peripheral resistance (32 per cent), hypotension associated with fentanyl (23 per cent) was caused by diminished output due to bradycardia (18 per cent). Load data,heart rate, and maximum dp/dt indicated moderate negative inotropic properties only of althesin. Using the complex haemodynamic parameter developed by Bretschneider the myocardial oxygen consumption was calculated. The energy demand of the heart decreased with etomidate, althesin and fentanyl by 14 per cent, 16 per cent and 32 per cent respectively. It is concluded that the risk of cardiovascular depression at induction in patients with impaired myocardial performance and coronary insufficiency can be minimized with etomidate and/or fentanyl.

Adult↗
PubMed1979

Calcium accumulation by human uterine microsomal preparations: Effects of progesterone and oxytocin.

A microsomal fraction was prepared from human pregnant uteri at term and at 6 to 19 weeks' gestation, and from nonpregnant uteri by differential centrifugation and purified on a discontinuous sucrose density gradient. This fraction bound calcium in the presence of adenosine triphosphate (ATP). ATP-dependent calcium binding in microsomal preparations was found to increase with advancing pregnancy. Addition of progesterone increased the ATP-dependent calcium binding, while addition of oxytocin decreased the ATP-dependent calcium binding. In combination, oxytocin and progesterone counteracted each other. The progesterone effect was specific for progesterone; three biologically inactive analogues had no effects on calcium binding. The actions of progesterone and of oxytocin on ATP-dependent calcium binding were found to be consistent with their respective in vivo uterine relaxing and contracting actions.

Adenosine Triphosphate↗
PubMed1979

5 alpha-Reductase activity in human placenta.

The concentration of 5 alpha-pregnane-3,20-dione in peripheral blood of pregnant women is higher than that found in blood obtained from nonpregnant women throughout the luteal phase of the ovulatory cycle. The in vitro synthesis of 5 alpha-reduced pregnanes from [3H]progesterone by placental tissue was investigated using tissue minces and homogenates in the presence of added nicotinamide-adenine dinucleotide phosphate. The metabolites, [3H]5 alpha-pregnane-3,20-dione and [3H]3 beta-hydroxy-5 alpha-pregnan-20-one, were isolated and characterized employing a combination of chromatographic techniques, derivative formation, and crystallization with authentic [14C]5 alpha-pregnane-3,20-dione and [14C]3 beta-hydroxy-5 alpha-pregnan-20-one to constant 3H:14C ratios. In short-term incubations with placenta homogenates, the apparent pH optimum for the synthesis of 5 alpha-pregnane-3,20-dione was 8.8. There was no evidence for the formation of 5 beta-reduced pregnanes from [3H]progesterone by placental tissue. The in vitro metabolism of [3H]progesterone by minces of five term placentas, during 1 hour incubations at pH 7.4, was studied. The rate of formation of 5 alpha-pregnane-3,20-dione varied from 109 to 197 pmoles/gm placental tissue/hr.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1976

Steroid anaesthesia (Althesin - CT 1341) and dorsal horn cell activities in feline spinal cord.

The effects of steroid anaesthesia (Althesin -CT 1341) on dorsal horn cells (laminae 4 and 5) were studied by extracellular recordings in the spinal cat. I.v. administration of Althesin (0.2 ml/kg) strongly depressed the spontaneous and evoked activities of both types of cells. No differences were found between cells activated by noxious or innocuous stimuli. These results emphasize the fact that the transmission of afferent messages is depressed by various anaesthetics at the level of the first synapses in the CNS. The depressive effects on lamina 5 cells could explain in part the analgesic effects of Althesin.

Alfaxalone Alfadolone Mixture↗