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Biomedical subjects

W Ladosky

Publications and source records attributed to W Ladosky.

At least 19 recordsLinked to original sources
PubMed2001

Chest mechanics in morbidly obese non-hypoventilated patients.

Seventy-seven patients with morbid obesity, body mass index (BMI) 40-69.9 kg m(-2), who were candidates for gastroplasty, were studied in our laboratory as part of a pre-operative survey. They had no complaints other than obesity and were not cyanotic. A group of 28 lean subjects (BMI 20-29.8 kg m(-2)) who were candidates for abdominal surgery, without any respiratory complaint, were included as controls. For each patient a pulmonary function test was performed, measuring slow vital capacity with expiratory residual volume (ERV), forced vital capacity (flow/volume) and maximal voluntary ventilation (MVV). In obese patients the MVV is reduced as BMI increases. This results in the reduction of expiratory flows and volumes. Forced expiratory volume in 1 sec (FEV1) is reduced in proportion to the FVC reduction and is related to MVV. It is suggested that the main consequence of the burden of the chest wall by increased adipose mass is a reduction in its compliance, making inspiration increasingly difficult, and resulting in lower static volumes and flows.

Adult↗
PubMed1987

Inhibition of the preovulatory LH surge after a catecholestrogen (2-hydroxyestrone) antiserum injection in the third ventricle of cycling female rats.

Administration of a catecholestrogen (2-hydroxyestrone, 2-OHE1) antiserum (2-OHE1-AS) in the third ventricle of cycling female rats, on the morning of proestrus, leads to a significant reduction in the afternoon LH surge. These responses are dose-dependent and can be observed even when the 2-OHE1-AS is injected on the diestrus morning. Almost similar results were obtained with an antiserum against 17 beta-estradiol (17 beta-E2). Nevertheless, the fact that the central immunoneutralization of 2-OHE1 impedes the preovulatory surge of LH at a time of high peripheral levels of 17 beta-E2 strengthens the idea of a specific role for 2-OHE1 in the control of cycling LH release.

Animals↗
PubMed1985

Hormonal influence on the response of the uterus of the Brazilian marsupial Didelphis albiventris to adrenergic drugs.

The influence of catecholamines on the estrogenized uterus of the Didelphis albiventris was studied in an in vitro preparation. It was observed that the D. albiventris uterus reacts to both alpha and beta-adrenergic agonists but not dopaminergic ones. Adrenaline is more potent in inducing a contractile response than is noradrenaline. Isoprenaline, when added to the bath, is able neither to induce a response nor to interfere with a contraction previously induced by acetylcholine. It is, however, able to block the contractile response brought about by electric field stimulation. In an in vitro preparation from animals previously treated with estrogen and progesterone, the sensitivity to both alpha- and beta-adrenergic drugs was greatly increased. This is demonstrated by a higher pD2 in progesteronized animals compared to that in estrogenized ones. The increased sensitivity to beta-agonists after progesterone treatment is illustrated by the fact that isoprenaline is effective in inducing a relaxation of the uterus, in these conditions. These results indicate that the Brazilian opossum should be included among those animals in which progesterone enhances uterine sensitivity to drugs.

Animals↗
PubMed1984

Influence of estrogen and progesterone on the uterine sensitivity in vitro to neuropituitary hormones in the Brazilian marsupial Didelphis albiventris: comparison with lactating animals.

The influence of different neuropituitary hormones on the contraction of the Brazilian opossum uterus in vitro was studied in spayed adults injected with (i) peanut oil (ii) estrogen or (iii) estrogen plus progesterone, and in a fourth group of lactating animals. Two parameters were analyzed from the dose-response curve: pD2 and the relative contractile response compared to the maximal one induced by oxytocin. When oxytocin was administered to the bath, neither pD2 nor the contractile force was affected by any hormonal treatment or lactation. Oxytocin, however, remained in any hormonal status, the most powerful agonist to induce uterine contraction. Lysine vasopressin was the weaker agonist in any hormonal status. It binds slightly less to the isolated uterus than to the hormone-treated one. The maximal contractile force remains unchanged when the uterus is from ovariectomized or steroid-treated animals. However, after lysine vasopressin, uterus from lactating opossum develops a less intense contractility than that observed in other groups. Arginine vasopressin induces a contractile force comparable to that induced by oxytocin in any hormonal status. The affinity of this peptide for the uterine receptor is significantly lower in ovariectomized and estrogen-treated animals; after progesterone injection or in lactating animals the receptor affinity for this hormone is increased to the level of the affinity for oxytocin. Receptor affinity for arginine vasotocin is reduced in any hormonal state and brought to a level comparable to that for oxytocin only in lactating animals. On the other hand, progesterone reduced the maximal contractile force induced by this neuropeptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1984

Hypothalamic nuclei catechol-O-methyl-transferase and the process of brain sexual differentiation.

The present review focuses on some aspects of the function of catechol-O-methyl-transferase (COMT) in the hypothalamic control of gonadotrophin release by the pituitary gland. The in situ influence of a catecholestrogen (2 OH.E2) on the amount of COMT in the hypothalamic nuclei involved in such control as well as on the process of sexual differentiation of the brain is also discussed. Catecholestrogens do not play a significant role in the induction of sexual differentiation and the observed action is probably a pharmacological one. It is difficult to understand why a substance whose structure is so closely related to that of estrogen is so much less active. Most probably the estrogen receptor in the cytosol at this stage of development is not able to recognize the catecholestrogen. Since catecholestrogens are not true virilizing substances they may be used to assess the critical levels of enzymes which are required to determine the sexual pattern of hypothalamic activity. The fact that the extent of the changes in COMT content of the hypothalamus is related to the amount of hormone used to induce virilization strengthens the view that sexual differentiation is the consequence of a genomic change during the critical period, which will induce an enzymatic pattern characteristic of the male acyclic pattern of gonadotrophin control. The finding that the COMT content of the hippocampus also changes in parallel to sexual differentiation leads us to speculate that perhaps sexual behavior may also be differentiated in the same way.

Animals↗
PubMed1983

Possible mechanism of action of 2-hydroxylated estradiol on the positive feedback control for LH release in the rat.

Evidence was given to support a positive role of 2-hydroxyestradiol on the LH surge. The catecholestrogen may act by its catechol A ring on the nucleus arcuatus COMT, consequently leaving the noradrenaline free. The result may be a longer action on the peptidergic terminal in the median eminence and an increase in the LH secretion by the pituitary. This assumption is supported by the observations that the catecholestrogen effect can be mimicked by homocystein, an aminoacid able also to inhibit COMT activity, having neither a steroid nor a catechol structure. The fact that alpha-MIT is able to prevent homocystein-induced increase in LH suggests that it is acting by protecting the local increase of the catecholamine. After ten years of intensive effort to understand the possible physiological role of the catecholestrogens, attention was mostly paid to its structural similarity to estrogen and a great deal of effort was made to understand its function by acting upon the estrogen receptor in the cytosol. The evidence for catecholestrogen action upon COMT, an outside membrane enzyme involved in the process of catecholamine degradation, supports the idea of a catechol action for 2-OHE2. The present evidence strongly supports the physiological importance of the catechol group in the 2-OHE2 in its action mechanism. However, a true physiological role for the catecholestrogens remains to be solved. The evidence we bring confirms once more that catecholestrogens may have a function and explains a new mechanism of action. However, the basic question concerning the true amount of catecholestrogen existing in the hypothalamic nuclei, either brought by the blood stream or locally produced, still needs to be solved: we cannot say whether the mechanism we described is a functioning one, whether it is just brought about by the experimental increase of the catecholestrogen or the artificial blockage of COMT.

Animals↗
PubMed1982

Morphological and physiological factors involved in the contractility of the spermatic cord and ductus deferens of the opossum (Didelphis albiventris).

The opossum spermatic cord is characterized by a thick skeletal muscle coat, provided by the great development of the cremasteric muscle. Acetylcholine induced a powerful contraction of the spermatic cord placed in an organ bath containing Heller's solution. This contraction was blocked by curare but not completely by atropine as is usual for skeletal muscle. However, the ductus deferens did not respond to acetylcholine or catecholamines under the same conditions. Specific histochemical methods for both catecholamines and acetylcholinesterases revealed that the ductus deferens musculature, composed mainly of circular fibres, is richly innervated by adrenergic and presumed cholinergic nerve fibres. The lack of responsiveness to the neurotransmitters could be explained by the absence of longitudinally arranged muscle. It is suggested that in the opossum the cremaster could participate in the mechanism of sperm transport.

Acetylcholine↗
PubMed1981

Changes in hypothalamic catechol-O-methyl-transferase during sexual differentiation of the brain.

1. An assay using [14C-methyl]-S-adenosyl-L-methionine was used to measure catecholamine-O-methyl-transferase (COMT) activity in the hypothalamus of newborn male and female rats from day 1 to day 12 and in adult animals after day 60. 2. There was no difference in COMT activity between sexes until day 8, when it became significantly higher in females. 3. Administration of 200 micrograms testosterone propionate to female rats at birth reduced the hypothalamic COMT level of the adult to that observed for male littermates. The response was dose-dependent in the range 50 to 200 micrograms. The hypothalamic content of COMT after puberty of male rats castrated at birth was comparable to that of post-pubertal females. 4. These results show that COMT, one of the enzymes involved in the control of brain biogenic amines, is also affected by the process of sexual differentiation of the brain.

Animals↗