Biomedical subjects

A Freud

Publications and source records attributed to A Freud.

At least 19 recordsLinked to original sources

PubMed1992

A convenient synthesis of N-succinimidyl-3-iodo-[125I]benzoate, a reagent for protein iodination.

A convenient procedure has been developed for the synthesis of N-succinimidyl-3-iodo-[125I]benzoate. The procedure involved the synthesis of chloromercuribenzoic acid, its esterification with N-hydroxysuccinimide (NHS) and exchanging the mercury moiety with radioactive iodine in the presence of an oxidant. The obtained product was attached to human serum albumin and its stability was compared with Chloramine-T (Ch-T) radioiodinated protein. The results indicated that the reagent-radiolabeled protein was stable for longer periods and the deiodination rate was significantly lower.

Chloromercuribenzoates↗

PubMed1991

The role of glycolysis and univalent ions in phthalocyanine-sensitized photohaemolysis of human erythrocytes.

Phthalocyanines sensitize human erythrocytes to red light in vitro and in vivo. The mechanism of photosensitization of haemolysis of red blood cells was studied using haemoglobin release in vitro as an endpoint. We have previously shown that the cation present in the incubation medium determines the rate of photohaemolysis, with the rate increasing in the order Li+, Na+, K+, Cs+, Rb+. With halogen anions, the rate increases in the order F-, Cl-, Br-. With F- in isotonic solution the rate was about two orders of magnitude slower than with Cl-, so that haemolysis was practically prevented. Fluoride slowed haemolysis at very low concentrations (less than 1 mM) with an apparent K1 of 0.1 mM in isotonic NaCl. Most of the effect disappeared when F- was added after light exposure, with a half-time of 1 min. The effect of F- was specific to phthalocyanine. Neither Photofrin-induced photohaemolysis nor gramicidin-induced haemolysis were inhibited by fluoride. Addition of 10 mM deoxyglucose prior to photosensitization enhanced haemolysis and reduced cellular ATP levels by about 50% compared to controls containing glucose. Haemolysis was preceded by a reduction in ATP levels in the presence of both glucose and deoxyglucose. No significant decrease in ATP levels was found following light exposure in the presence of 0.75 mM F-. It is concluded that glycolysis and ATP are important in preventing photohaemolysis. The protective effect of F- may be related to its inhibition of a fast early reaction which triggers the events leading to photohaemolysis induced by phthalcyanine.

Anions↗

PubMed1990

Progesterone and estradiol plasma levels in neonatally irradiated cycling rats.

Female rats which were exposed to a single low dose of gamma irradiation (6R or 15R) at the age of 8 days produce smaller litters when mature than untreated controls. The possibility that the impaired fertility resulted from altered ovarian activity as reflected by changes in plasma levels of progesterone or estardiol was investigated. Plasma levels of both steroids were determined throughout the day of proestrus. Progesterone level was also determined in 6R animals on the day of weaning. The maturity of such irradiated rats was assessed by observing the time of vaginal opening. The results indicated that the preovulatory peak of progesterone was delayed in the 6R rats whereas in the 15R group its levels were significantly lower. On the other hand no differences in estradiol plasma levels were noticed between the groups. The higher level of progesterone in the 6R animals was not evident on the day of weaning and was even in both groups, but vaginal opening in the irradiated rats was significantly delayed. The elevated level of progesterone might be responsible, among other endocrine changes, for the lower fertility of neonatally irradiated mature female rats.

Animals↗

PubMed1990

Neonatal low-dose gamma irradiation-induced impaired fertility in mature rats.

The reproductive capacity of mature rats at the age of 8 days was studied following neonatal exposure to 0.06 Gy dose of gamma-radiation. Decreased litter size and reduced body weight of the pups on weaning day, but not at parturition, were observed in female rats. The reduced litter size was not associated with impaired ovulation, impaired uterine implantation or mortality in utero, but resulted from increased death rate or at near parturition. Of the neonatally irradiated males 29% were found to be sterile and had degenerated or necrotic testes. The testicular damage and the reduced growth rate of the offspring of the irradiated females demonstrate the extreme sensitivity of the immature reproductive system to ionizing radiation, even at very low doses.

Animals↗

PubMed1989

Changes in the endocrine system controlling reproduction in mature female rats neonatally exposed to a low dose of gamma irradiation.

Female rats which were exposed to a single low dose of gamma irradiation (6R or 15R) at the age of 8 days produce smaller litters when mature than untreated controls. The possibility that such an impaired reproductive performance could result from changes in the endocrine system was investigated. Plasma levels and hypophyseal contents of LH and FSH, plasma levels of testosterone and hypothalamic content of GnRH were determined. The responsiveness of the pituitary to a single injection of GnRH (50 ng/rat) given on day of proestrus was evaluated. The results indicated that plasma levels of FSH but not of LH were lower in the irradiated rats. This was accompanied by changes in the hypothalamic content of GnRH. The possibility that the pituitary was sensitive to gamma irradiation was excluded. Twenty five minutes after a single injection of GnRH a 2-5 fold increase in LH plasma levels was noticed in all the groups, thus indicating that the reduced fertility could not be attributed to hypophyseal malfunction but rather to an impaired hypothalamic stimulus. Moreover, the lower levels of FSH might result from the significantly elevated levels of testosterone which were observed in the irradiated rats. Apparently, neonatal exposure to a single low dose of gamma irradiation resulted in a new hormonal equilibrium which was responsible for the reduced fertility in such rats.

Animals↗

PubMed1988

Altered ovarian responsiveness to gonadotropins in neonatally irradiated immature rats.

Female rats which were exposed to a single low dose of gamma irradiation (6R or 15R) at the age of 8 days produce smaller litters when mature than untreated controls. In order to study the possibility that such an impaired reproductive performance could result from a reduced ovulation rate, neonatally irradiated females were treated with PMSG (12 iu/rat) at the age of 26 days. Another group of rats, similarly treated, was further injected with hCG (5 iu/rat) 48 hours later. Animals were killed 48, 55, 60 and 72 hours after PMSG treatment or 72 and 120 after hCG injection. The results indicated that PMSG treatment increased the ovarian weight of non-irradiated controls as well as of irradiated rats and in all animals induced a proestrus like profile of LH. Only a combined treatment of PMSG and hCG resulted in ovulation and corpora lutea formation with significantly increased numbers of corpora lutea in the ovaries of the irradiated rats. The latter was associated with higher progesterone plasma levels not correlated to the number of corpora lutea. The gradual decrease in the number of ovarian binding sites for hCG with increased radiation dose and the increased association constant in the 15R group could not explain the increased sensitivity of the ovary to exogenous gonadotropins which results from neonatal exposure to low doses of gamma irradiation.

Animals↗

PubMed1979