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Biomedical subjects

M Roos

Publications and source records attributed to M Roos.

At least 109 records · Page 6Linked to original sources
PubMed1976

Progesterone action on estrous rhythm in the rat following ventromedial nucleus lesions.

Small bilateral lesions of the hypothalamic ventromedial nucleus (SVMN) were produced in 4 day cyclic female Wistar rats by passing a 2 mA cathodic current through stereotaxically oriented platinum unipolar electrodes for 7 sec. The 24 h lengthening of cycle which occurred in 111 our ot 208 females was shown to depend upon lesion placement. Early s.c. injection of 0.75 or 1.5 mg progesterone caused 24 h cycle prolongation more frequently in SVMN-lesioned females with maintained 4 day cycles than in 4 day cyclic unoperated, sham VMN-lesioned, or dorsomedial nucleus (DMN) lesioned females. This effect proved to be related to lesion placement. It was therefore concluded that the VMN is involved in the mechanisms whereby progesterone controls estrous cycle duration in the rat.

Animals↗
PubMed1976

Hormonal mechanisms involved in the control of oestrous cycle duration by the odour of urine in the rat.

The mechanisms involved in the reduced cycle duration following exposure to the odour of urine were studied in natural and experimental 5-day cyclic female Wistar rats. A decrease in the rate of ovarian progesterone secretion from the morning of dioestrus I to that of dioestrus II was observed in females whose cycle duration was reduced from 5 to 4 days following exposure to the odour of rat urine. No decrease in ovarian progesterone secretion occurred in females maintaining a 5-day cyclicity despite exposure to this odour. An increase in follicular growth was noted in females with cycle duration reduced from 5 to 4 days, when compared with those maintaining a 5-day rhythm. As a result of exposure to the odour of urine no reduced cycle duration occurred in females with cycles lengthened from 4 to 5 days as a result of progesterone injection on dioestrus I of 4-day cycles. Hence the decrease in ovarian progesterone secretion, induced by exposure to the odour of urine, is considered to cause a speeding up in follicular growth, thereby reducing oestrous cycle duration in 5-day cyclic rats.

Animals↗
PubMed1976

Effect of long-term alcohol consumption on the half-life of tetracycline and doxycycline in man.

Elimination of the bacteriostatics tetracycline and doxycycline was compared in patients on long-term alcohol consumption to that in healthy controls. The half-life of doxycycline but not that of tetracycline was significantly shorter in alcoholics than in controls and in some patients the serum concentration of doxycycline decreased below the generally accepted minimum therapeutic concentration when dosed once daily. So, the dosing twice daily might be indicated especially if additional inducing drugs are used.

Doxycycline↗
PubMed1976

[Demonstration of a critical period of ovarian activity in the control of early receptivity induced by estrogen in the female rat with 4-day cycles].

A significant decrease in early receptivity during the night from dioestrus II to prooestrus was observed in estrogen-treated 4-day cyclic rats following bilateral ovariectomy on dioestrus II at 4-5 p.m. Early receptivity appeared then to be dependent on the presence of ovary at this stage of the cycle. The mechanism whereby the adrenals may compensate for the ovaries when removed on dioestrus I, at 10-11 a. m. (Roos et al. 1973), was not observed in the present experimental conditions.

Adrenal Cortex↗
PubMed1975

Luteinizing and ovulatory action of oestradiol in the pregnant rat.

Oestradiol injection on Day 10 of pregnancy in rats, resulted in either ovulation or luteinization in 50% of cases on Day 12. Cytological data showed that the number of pituitary LH cells decreased significantly on Day 11 in all oestradiol-treated animals whether responsive or not to oestrogen by ovarian modifications, while the number of pituitary FSH cells only decreased significantly in females with characteristic ovarian signs of preovulation. Bioassay of pituitary FSH confirmed the cytological data. It is concluded that ovulation and luteinization only occurred in the pregnant rat when oestradiol triggered off a synchronous release of LH and FSH.

Animals↗
PubMed1975

[New data on the "critical period" of the luteinizing action of estradiol benzoate in female rats].

The luteinizing action of oestradiol benzoate (OB) has been studied in 4-day cyclic female Wistar rats submitted to a dose of 10 mug on the morning of dioestrus I at 10-11 a.m. In a first experimental series a blockage of luteinization was observed in females injected with pentobarbital (PB) either on dioestrus I at 11 a.m. and 5 p.m. respectively or on dioestrus II at 1:30 p.m. In the second series the blockage of luteinization only occured in females injected with PB on dioestrus II at 1:30 p.m. Early mating during the night following dioestrus II overcame this action of PB. The luteinizing effects of OB were therefore concluded to be dependent on the activation on the afternoon of dioestrus II, of the nervous hypothalamic structures. They were also shown to depend on the sensitivity to PB and/or to OB, on the day of dioestrus I, of the hypothalamo-pituitary system.

Animals↗