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Biomedical subjects

A Chatterjee

Publications and source records attributed to A Chatterjee.

At least 361 records · Page 20Linked to original sources
PubMed1976

Microdosimetric structure of heavy ion tracks in tissue.

Energy dissipation in tracks of high energy heavy ions in tissue shows a lateral spread of several to many microns depending on the energy of the primary particle. Complete dosimetric characterization, therefore, requires in addition to the Linear Energy Transfer (LET) information on the radial energy distribution. The theory of track structure distinguishes two regions: core and penumbra. The core is a narrow central zone with a radius in tissue far below 1 micron where energy deposition occurs mainly in processes of excitation and electron plasma oscillation. According to the Equipartition Principle, half of the total energy dissipation accrues in this manner. The penumbra is a peripheral zone enveloping the core where energy deposition occurs mainly in ionization events by energetic secondary electrons released by the primary particle in the center of the core traveling at rather high speed thus spreading laterally. The extension of the penumbra depends in a complex manner on the maximum transferable energy to electrons which in turn depends on the speed of the primary particle. Local energy density in the penumbra decreases with the square of increasing radius. It therefore amounts only to a very small fraction of the core density already a few microns away from the center. In general terms, track structure can be described as exhibiting a core of enormous energy density with lateral dimensions remaining entirely on the submicroscopic level surrounded by a penumbra where energy density drops precipitously to very small levels. The relationships are illustrated with micrographs of different sections of a heavy particle track in nuclear emulsion and their counterpart graphical plots.

Elementary Particles↗
PubMed1976

The possible mode of action of prostaglandins: X. Antagonism between prostaglandin F2a and prolactin or human chorionic gonadotropin: a comparative study.

A comparative assessment of the efficacy of prolactin or HCG in reversing the luteolytic property of a single dose (2.0 mg/kg) of PGF2a was conducted in pregnant (day 10) rats. It was found that prolactin maintained pregnancy in 90% of the test animals. HCG though found to maintain pregnancy in 70% of the PGF2a-treated pregnants, the fetal survival rate was, however, recorded to be 62% against the control value of 98%. Conversely, prolactin replacement maintained the fetal survival rate as high as 93.4%. Moreover, the growth of the fetuses, placentae and corpus luteum in the pregnants having prolactin in conjunction with PGF2a was also found to be greater compared to the animals which had a combined regimen of PGF2a and HCG, but identical to controls. On the other hand, similar combined regimen when applied to hysterectomized pregnant rats, it was observed that though the vaginal diestrus was maintained by the prolactin or HCG in the presence of PGF2a, the prolactin regimen was found to be superb compared to HCG in the maintenance of luteal weight and functional activity. It was concluded that the antifertility effect of PGF2a in the rat is primarily the consequence of luteolysis and prolactin seems to be a much more appropriate hormonal replacement compared to HCG, a long-acting LH, in antagonizing the luteolytic property of PGF2a.

Animals↗
PubMed1976

The possible mode of action of phostaglandins. XII. Differential effects of phostaglandin F2alpha in inducing premature evacuation of conceptos in the intact and castrated pregnant rat.

A single injection of 2.0 mg/kg prostaglandin F2alpha(PGF2alpha) on day 18 of pregnancy was consistent in inducing premature labor by 72 h following the injection. Conversely, castration before PGF2alpha on day 18 of pregnancy made the animals almost inert to PGF2alpha and only 20% of the treated animals showed premature evacuation of the conceptus. Injection of 10mug of estradiol cyclopentylpropionate (ECP) on day 18 was, however, found to be effective in emptying the gravid uteri of 100% castrated pregnants by 72 h. Indomethacin, a consistent inhibitor of prostaglandin biosynthesis and release, along with ECP in an identical experimental situation was found to be ineffective in reversing the ECP-induced premature parturition in castrated pregnants. The importance of intact ovary for the action of PGF2alpha concerning premature labor in rats has been discussed.

Animals↗
PubMed1976

A histochemical study on the differentiating vertebral column of chick.

1. The differentiation of the vertebral elements of the cervical region of the chick has been studied from 4 to 23 day age group counted from the day of the commencement of incubation. 2. From the histochemical tests it appears that chondrogenesis does not take place simultaneously in all the areas of the vertebra. 3. Histochemical changes usually follow histological differentiation. 4. The findings have been discussed in the light of inducing principles by the spinal cord.

Animals↗
PubMed1976

Melanocytic activity in leprosy lesions with special reference to cellular infiltrate.

To assess the correlation, if any, between the clinical hypopigmentation in leprosy affected skin and the inflammatory cellular infiltrate in d rmis, skin tissue sections from the maculo-anaesthetic and tuberculoid lesion of 50 cases were studied with Dopa and H & E stains. The results are indicative of (i) proportionate lack of Dopa oxidase activity in the hypopigmented leprosy lesions in commensuration with the relative degree of clinical hypopigmentation; (ii) cellular infiltrate is not related with the clinical hypopigmentation or dopa oxidase activity.

Child↗
PubMed1976

Pregnant mare's serum gonadotrophin. I. Progesterone or prolactin and the reversal of antifertility efficacy of pregnant mare's serum gonadotrophin.

A single consistent luteolytic dose of 10 IU PMSG given on day 5 of pregnancy caused complete resorption of foetuses and placentae associated with a polyfollicular ovarian state in rats. Concomitant treatment with progesterone or prolactin given concurrently with PMSG was found to overcome the antifertility efficacy of PMSG and maintained the endocrine balance favouring pregnancy maintenance. It was postulated that the PMSG-induced ovarian polyfolliculogenesis might be responsible for luteolysis of the corpus luteum gravidarum.

Animals↗
PubMed1975

The possible mode of action of prostaglandins IX-prostaglandin F2alpha involvement in the reversal of ovulation blockade by ergocornine in rats.

A single injection of 1 mg ergocornine methanesulphonate to semispayed rat on day 3 of the cycle was found to block ovulation. However, the animals showed regular compensatory hypertrophy of the remaining ovary. Prostaglandin F2alpha (PGF2alpha) of 2.0 mg/kg bw on days 3 and 4 in the ergocornine-blocked semispayed rats consistently reversed the blocking effect and the animals showed compensatory ovulation and ovarian hypertrophy. It was moreover observed that the ergocornine-treated mated animals did not become either pregnant or pseudopregnant, but returned to normal cycle as usual. Conversely, the animals which had combined regimen of ergocornine and PGF2alpha became pregnant and the number of embryonic swellings in a single horn and their average weight were statistically identical to their experimental controls. The possible involvement of PGF2alpha in the mechanism of follicular rupture has been discussed.

Animals↗
PubMed1975

The possible mode of action of prostaglandins: VIII - cortisone, reserpine and the reversal of the antifertility efficacy of prostaglandin E1 in rats.

A single injection of prostaglandin F1 (PGE1) of 5 mg/kg body weight on Lay 13 of pregnancy caused a consistent luteolysis and resorption of fetuses in rats by Day 20. A concomitant regimen of cortisone, a consistent blocker of nonspecific stresses or reserpine, an adrenergic nerve blocking agent as well as a specific inhibitor of GRF and PIF, concurrently with PGE1 consistently effective in preventing the deleterious efficacy of PGE1 and maintained the growth of the fetuses, placentae, ovaries and corpora lutea as healthy as recorded in the controls. On the basis of experimental documentation it is believed that the PGE1-caused fetal demise is possibly due to a break up of an appropriate hormonal synchronization rather than an over stimulation of uterine smooth musculature.

Animals↗
PubMed1975

The possible mode of action of iproniazid. I. Differential luteolytic effect of iproniazid before and after the establishment of placental adolescence.

Iproniazid, a very specific monoamine oxidase inhibitor, at a dose level of 200 mg/kg body weight induced luteolysis and caused lysis of deciduomata as well as resorption of the established embryos. Exogenous replacement of prolactin, a most consistent stimulant of the endocrine functioning of corpus luteum, or progesterone absolutely reversed the adversity developed following iproniazid injection. Moreover, failure of iproniazid even at a higher dose level in the deviation of the normal sequence of pregnancy after the establishment of placental adolescence strongly tempting to suggest that iproniazid could only show its luteolytic effect when the hypothalamic-pituitary complex is exclusively involved in the maintennance of pregnancy.

Animals↗