Preovulatory changes in ovarian cyclic AMP and prostaglandins in immature rats injected with PMSG

In 28-day-old rats injected with PMSG, ovarian cyclic AMP and PGE and PGF increased 2 and 3-4 h respectively after the LH peak.

Pre-ovulatory changes in rat follicular cyclic AMP and sensitivity to gonadotrophins

Stimulation of ovarian follicles by high concentrations of gonadotrophins has been reported to induce a refractory state in the follicles to further stimulation by the same agent. The present study was undertaken to determine whether a physiological gonadotrophic stimulus would induce a similar desensitization.

The levels of cyclic AMP (cAMP) were measured in rat pre-ovulatory follicles before and after the estimated period of gonadotrophin release. The PMSG injected pre-pubertal rat was used as a model of spontaneous ovulation as previously described. Follicles were explanted before and after the period of gonadotrophin release on the day before ovulation (day 30 in the present model) and cAMP was measured either directly or after 1–2 h of incubation. The follicles explanted in the evening of day 30 showed higher levels of cAMP than those isolated in the same morning irrespective of their being incubated or not. Follicular lactic acid production and progesterone synthesis as measured in the incubation medium showed the same pattern. The increase in all three parameters in "evening follicles" could be prevented by giving the animals pentobarbitone before the estimated gonadotrophin release. When the follicles were extirpated in the evening of day 30 and incubated in the presence of LH or FSH, significantly higher concentrations of the two hormones were needed to elicit a further increase in cAMP as compared to follicles isolated in the morning of the same day or from rats treated with pentobarbitone.

It is concluded that the pre-ovulatory surge of gonadotrophins induces a desensitization of the cAMP system of rat ovarian follicles toward further action by LH or FSH. This refractory state, however, is not complete but relative under physiological conditions.

In the rat, the duration of this phenomenon seems to coincide with the slight but significant elevation of follicular cAMP and to last from a few hours after the gonadotrophin surge up to ovulation. Possible mechanisms of this effect as well as its purpose are discussed.

Endocytosis of Salmonella typhimurium 395 MS and MR10 by HeLa cells

Monolayer of HeLa cells were examined for their ability to endocytose Salmonella typhimurium 395 MS (wild) and MR10 (chemotype RD). Monolayers treated with the glycolytic inhibitors iodoacetic acid (IAA) or N-ethylmaleimide (NEM) or the respiratory inhibitor sodium azide (NaN3) or cytochalasin B (CB) were incubated with S. typhimurium. The numbers of cell-associated (intracellular plus cell-membrane attached extracellular) and intracellular bacteria were determined by viable counts, together with the HeLa cell ATP levels. IAA and NEM at concentrations 10(-4)M and 10(-3)M decreased significantly the number of intracellular MR10 and the cellular ATP levels, but did not influence significantly the total number of cell-associated bacteria except for 10(-3)M IAA which slightly increased the association. On the other hand, NaN3 at concentrations 10(-4)M and 10(-3)M did not affect the number of associated or intracellular bacteria, or the cellular ATP levels. CB at concentrations of 5, 10 and 20 microgram/ml increased the number of associated bacteria, decreased the number of intracellular bacteria and caused a small decrease in cellular ATP levels. Thus, HeLa cells may internalize S. typhimurium by an energy-requiring, glycolysis-dependent process. CB had a dose-dependent inhibitory effect on the internalization without influencing significantly the HeLa cell ATP levels. This indicates that CB might affect the internalization process by some means other than decreasing the ATP content.

A rapid semiautomated bioassay of gentamicin based on luciferase assay of bacterial adenosine triphosphate

A rapid semiautomated bioassay of gentamicin in serum based on the effect of gentamicin on intracellular adenosine triphosphate (ATP) levels in bacterial cultures is presented. The ATP assay was performed with the firefly luciferin/luciferase system and results were compared with an agar diffusion technique. The lower limit of detection was set at 1 microgram/ml. The accuracy of the ATP assay expressed as a recovery of gentamicin over the range 1--8 microgram/ml was 98--103% and S.D. varied between 11-15%. The reproducibility was approximately within the same limits. Other antibiotics tested did not interfere with the determination of gentamicin. 112 clinical serum specimens containing gentamicin alone (N = 55) or in combination with other antibiotics (N = 57) were assayed and results with the two methods compared (r = 0.94). Volumes required were 0.1 ml serum and results were available within 3 h.

Hydrosalpinx simplex as seen by the scanning electron microscope

Five cases of hydrosalpinx simplex were studied by light microscopy and scanning electron microscopy (SEM). Comparison was made with normal fallopian tube epithelia. By light microscopy numerous ciliated cells as well as nonciliated cells were found in both hydrosalpinx and normal tubal material. In hydrosalpinx material the epithelium was found to be compressed to one-sixth its usual height. The SEM survey of large areas of hydrosalpinx did not reveal any deciliation. In fact, the mucosa of the hydrosalpinx did not differ conspiciously from that of a healthy fallopian tube. However, some nonciliated cells with collapsed areas were revealed by SEM. The significance of the compressed areas is unknown.

Cerebral dysfunction in alcoholism and presenile dementia. A comparison of two groups of patients with similar reduction of the cerebral blood flow

Fifteen chronic alcoholics and 15 presenile patients were matched in pairs with regard to their mean hemisphere cerebral blood parameters-an index of brain metabolism. The distribution of the regional cerebral blood flow was similar in the two groups. The alcoholics performed significantly better in all psychometric tests than the presenile patients and more alcoholics than presenile patients were still employed and working. Nine presenile patients and one alcoholic showed symptoms indicating brain stem dysfunction. The measurements of the cerebral blood blow were made at rest while the psychometric testings and the evaluation of the social performance gave information about the brain at work. It is suggested that cerebral dysfunction in alcoholics to some extent can be partly overcome by brain activation procedures. In contrast, the defects of higher mental functions in presenile dementia cannot be compensated for.

Effects of ampicillin on intracellular levels of adenosine triphosphate in bacterial cultures related to antibiotic susceptibility

Short time effects of ampicillin on viability and levels of intracellular ATP were studied in bacterial cultures and a close relationship between intracellular ATP levels and viability was demonstrated. The connection between the effects observed and MIC values is discussed. The possibility of using the phenomenon for rapid antibioitc susceptibility testing was studied in clinical isolates incubated for 2 hours followed by luciferase assay of intracellular ATP. A positive correlation was demonstrated between ampicillin-induced decreases in intracellular ATP and inhibitory zone diameters, as measured by the agar diffusion technique.

Streptococcal types in impetigo and acute glomerulonephritis among children in Addis Ababa

Studies on the streptococcal epidemiology of impetigo in children below 12 years of age in Addis Ababa indicated that most streptococci isolated belonged to the classic serological impetigo strains. Streptococcal type 9 seemed to be a new impetigo strain. Several cases of severe acute glomerulonephritis on impetigo basis were observed during the study.

The effect of halothane anaesthesia upon cerebral oxygen consumption in the rat

The influence of halothane (0.6 and 2%) upon cerebral (cortical) blood flow (CBF) and cerebral metabolic rate for oxygen (CMRo2) was studied in artificially ventilated rats, using a modified technique of Kety & Schmidt (1948). The values obtained in halothane anaesthesia were compared to those recorded in nitrous oxide anaesthesia, or to those measured in unanesthetized animals given an analgesic drug (fentanyl citrate). Although it could be confirmed that halothane induces vasodilatation in the brain, there were relatively small differences in CBF between the groups. The results demonstrate that, in the rat, halothane depresses CMRo2 in a dose-dependent way. With 0.6% halothane, CMRo2 was reduced by 20-30% and, with 2% halothane, CMRo2 was reduced by about 50%. Thus, in the rat the effect of 2% halothane upon metabolic rate is comparable to that observed in barbiturate anaesthesia.

Brain energy metabolism during the process of dying and after cardiopulmonary resuscitation

In order to study the problem of how fast and to what degree severe hypoxic brain tissue changes are reversed after reoxygenation, we challenged the viability of the brain by exposing experimental animals to anoxia of such a duration that cardiopulmonary resuscitation was just possible. The brain tissue concentrations of glucose, lactate, pyruvate and of ATP, ADP, AMP and phosphocreatine were determined. Two series of experiments were carried out. In the first, groups of rats deprived of oxygen for 1, 2, 4 and 6 min were studied in order to show brain tissue changes in the period of impending death as well as the changes coinciding with the onset of clinical death (blood pressure zero). In addition, one group maintained at a rectal temperature of 37 +/- 0.5 degrees C and ventilated for 60 min with an oxygen free gas mixture was included aimed at representing a state of irreversibility. In the second series, restitution after 6 min of no oxygen supply was studied 10 min, 1/2 h, 1 h, and 2 h after cardiopulmonary resuscitation. Attempts were also made to correlate biochemical changes to EEG status and to clinical recovery. The restitution study showed that oxidative phosphorylation of the brain tissue was rapidly resumed with normalization of the adenylate energy charge in all animals in which the pump function of the heart could be restored by our artificial means. However, there was a strikingly poor correlation between recovery of mitochondrial function and restitution of EEG or clinical recovery. Thus, it seems likely that a delayed functional restitution is not due to energy failure but to other biochemical changes or to biophysical alterations not revealed by the present type of study.

Visualization principles in thin-layer immunoassays (TIA) on plastic surfaces

Macromolecules may adsorb firmly as a monolayer to plastic surfaces and still retain their property to react specifically with antibodies. In the present communication four different principles for visualization of such antigenantibody interactions on plastic surfaces are described. In addition, a diffusion-ingel method for quantitation of antibodies is presented. The described methods offer simple, sensitive and accurate means of assaying antigen-antibody reactions.

The longitudinal course of para-natal emotional disturbance

Ninety-five nulliparous women were interviewed during pregnancy and 4 months post partum. The possibility of predicting mental disturbance post partum from that during pregnancy was studied. When the woman was mentally disturbed during pregnancy, the prognosis was better in the case of a poor social situation at the time of the pregnancy than in the case of a good social situation. Negative attitude towards further pregnancies and repudiation of the own mother, however, implied unfavourable prognosis. In the case of a woman without mental symptoms during pregnancy, denial of the pregnancy and sensations connected with it suggested poor adaptation post partum.

Effects of hypothermia and hyperthermia on brain energy metabolism

The influence of elevated and reduced body temperatures upon the metabolic state of the brain was evaluated from the tissue concentrations of phosphocreatine (PCr) ATP, ADP and AMP and from the concentrations of glucose, lactate and pyruvate in immobilized and artificially ventilated rats anesthetized with 70% N2O. The results were compared to the results obtained in normothermic animals. It was found that rats with body temperatures of 32 degrees and 22 degrees C had the same brain tissue concentrations of high energy phosphates and the same adenylate energy charge as the controls, but hypothermia led to a progressive decrease of both cerebral and arterial lactate and pyruvate concentrations. A metabolic acidosis but no excess lactate appeared in the blood. At a body temperature of 42 degrees C, the metabolic pattern in the brain agreed with a state of hypoxia at a time when there was no sign of substrate depletion. Arterial blood showed excess lactate which may indicate an inadequacy of the oxygen supply also to other tissues.

The effect of phenobarbitone anaesthesia on blood flow and oxygen consumption in the rat brain

The influence of phenobarbitone anesthesia on blood flow (CBF) and oxygen consumption (GMRO2) was evaluated in the rat brain, using a method that quantitatively measures CBF in mainly cortical areas. The data were compared to those obtained in animals under fentanyl citrate analgesia. Body temperature and arterial CO2 tension were maintained close to normal values in all groups. With 50 mg/kg of phenobarbitone, CBF and CMRO2 were reduced by about 20%. With 150 or 250 mg/kg, further reductions in CBF and CMRO2 were observed. At 250 mg/kg, CBF was reduced to one third, and CMRO2 to about 50% of normal. The results suggest that little further reduction in CBF or CMRO2 can be expected if the dose of phenobarbitone is increased above 250 mg/kg.

Effects of LH and HCG on the metabolism of the prepubertal rat ovary: stimulation of amino acid transport, protein synthesis, and glycolysis

It has earlier been reported from this laboratory that FSH can stimulate amino acid uptake, protein synthesis and glycolysis in the isolated prepubertal rat ovary. In the present investigation to the effects of LH and HCG were studied. The hormones were injected to prepubertal female rats, and the ovaries were extirpated for incubation in Krebs bicarbonate buffer 120 min later. Injected of 1 mu g/100g body weight of a bovine LH preparation (NIH-LH-B8) produced a significant increase in the in vitro uptake of (14C) alpha-amino-isobutyric acid (14C)AIB) and (3H)leucine as well as of the incorporation of radioactivity into the ovarian protein. Higher doses (10 and 100 mu g) of NIH-LH-B8 gave only minor futher increases. Lactic acid production during the incubation period was also measured as a determination of the rate of glycolysis. Lactic acid production was stimulated by the LH injections with a clear dose-response between 0.1 and 10 mu g/100 g body weight. The effects of LH were also investigated with shorter intervals between the injection of the hormone and the extirpation of the ovaries. While lactic acid production was maximally stimulated at a time interval of 30 min (the shortest time interval studied), 60 min was necessary for the stimulation of amino acid uptake and amino acid incorporation into protein. Injections of HCG mimicked the effects of LH on all parameters studied.

Characteristics of the cyclic 3',5'-AMP formation in isolated ovarian follicles from PMSG-treated immature rats after stimulation in vitro with gonadotrophins and prostaglandins

Isolated pre-ovulatory follicles from PMSG-injected immature rats, described in a previous publication, have been used for the investigation of the pattern of cyclic 3′,5′-AMP synthesis after in vitro addition of gonadotrophins and prostaglandins. The follicles were incubated in a modified Krebs bicarbonate buffer for periods up to 4 h and the cyclic 3′,5′-AMP content in tissue and medium was analyzed with the protein binding assay of Gilman (1970).

Addition of LH, FSH or prostaglandin E2 (PGE2) increased the cyclic 3′,5′-AMP level in follicular tissue dramatically. HCG and TSH, but not STH or prolactin, also induced a similar increase. The effect of FSH was blocked by a highly specific antiserum to LH. The effect of LH had a maximum after approximately 1 h of incubation, whereas the maximal effect of PGE2 was seen between 5 and 15 min of incubation. When LH was present in the incubation medium a significant release of cyclic 3′,5′-AMP into the medium occurred. Theophylline potentiated the effects of LH and PGE2.

The different time-courses of the effects of LH and PGE2 on the cyclic 3′,5′-AMP production by follicular tissue are discussed in relation to the hypothesis of prostaglandins as obligatory mediators of all LH effects on the ovary (Kuehl et al. 1970).

Acute effects of gonadotrophins and prostaglandins on the metabolism of isolated ovarian follicles from PMSG-treated immature rats

Pre-ovulatory follicles from immature rats injected with a low dose of PMSG have been used for studies of carbohydrate and protein metabolism in vitro. The follicles were isolated by free-hand dissection and incubated in modified Krebs bicarbonate buffer for periods up to 4 h. The lactic acid content of the medium was analyzed after various incubation periods. In most experiments the tissue uptake of [14C]α-amino-isobutyric acid and [3H] leucine as well as the incorporation of [3H] leucine into follicular protein were determined.

Addition of LH or FSH to the incubation medium markedly stimulated the production of lactic acid, whereas prostaglandins of the E-type were less effective. Prostaglandin F2α and dibutyryl cyclic 3′, 5′-AMP had no effect at all. No in vitro effects were seen on the uptake and incorporation af labelled amino acids. When LH or FSH was injected to the animals in vivo 1 or 2 h before incubation of the follicles, the lactic acid production was also stimulated, but only the injection of LH stimulated the protein incorporation of [3H] leucine.

Effects of gonadotrophins and cyclic 3',5'-AMP on in vitro incorporation of ( 3 H)uridine into RNA of the prepubertal rat ovary

In vivo and in vitro effects of FSH and LH on in vitro incorporation of [3H]uridine into RNA of the prepubertal rat ovary have been studied. RNA was fractionated with composite agarose-polyacrylamide gel electrophoresis. When FSH was injected into the prepubertal rats 4 h before incubation of the ovaries, the incorporation of labelled uridine into total RNA was decreased showing relatively more radioactivity concentrated to the RNA fractions lighter than 28S as compared to the controls. These effects were not seen when FSH was added to the incubation medium in vitro. When LH was added in vitro to the isolated ovaries a higher percentage of incorporated radioactivity was concentrated in the RNA fractions heavier than 28S without any change in the incorporation of [3H]uridine into total RNA. LH administered in vivo 30 min before incubation of the ovaries gave the same change in the labelling pattern between the RNA fractions as LH in vitro but in addition showed a decreased incorporation of radioactivity into total RNA.

The in vitro effects of cyclic 3′,5′-AMP were also studied. When prepubertal rat ovaries were incubated in 10 mmol/l of this cyclic nucleotide, the incorporation of [3H] uridine into total RNA was decreased without any change in the labelling pattern.