Changes in plasma thyroxine concentrations in male and female starlings (Sturnus vulgaris) during a photo-induced gonadal cycle

Previous studies have shown that the thyroid must be important during the onset of photorefractoriness because thyroidectomised starlings (Sturnus vulgaris) do not become photorefractory. Therefore, to determine changes in plasma thyroxine during the onset of photorefractoriness, starlings were kept on photoperiods which induce photorefractoriness at different rates. Four groups of males and females were transferred from 8 hr light:16 hr darkness (8L:16D) to either 18L:6D, 13L:11D, 11L:13D, or 8L:16D and weekly blood samples were taken and assayed for thyroxine. In males and females on the two longer photoperiods, plasma thyroxine increased to a peak after 2-3 weeks. In those on 18L:6D, this was followed by a second peak after 9 weeks. Both 18L:6D and 13L:11D induced photorefractoriness. In birds held on 11L:13D, which became sexually mature but did not become photorefractory, there was no change in thyroxine. The results demonstrate that an increase in thyroxine concentration is associated with the onset of photorefractoriness.

Growth-inhibitory activity of lymphoid cell plasma membranes. I. Inhibition of lymphocyte and lymphoid tumor cell growth

Membranes isolated from normal spleen cells or lymphoid tumor cells were found to inhibit in vitro growth of several murine tumor cell lines including a B cell hybridoma, a thymoma, and a mastocytoma. 50% inhibition occurred at membrane protein concentrations of 60-100 micrograms/ml. A similar concentration dependence was found for inhibition of [3H]-thymidine incorporation by tumor cells and for the lipopolysaccharide-induced mitogenic response of normal spleen cells. The inhibitory activity co-purified with the plasma membrane upon fractionation of crude membranes. Membrane solubilization with deoxycholate followed by dialysis to remove the detergent gave good recovery of inhibitory activity in the resulting reconstituted membranes. Membrane-mediated growth inhibition resulted from a decreased rate of proliferation and not from increased cell death. A toxic effect of the membranes was further ruled out by the finding that increasing the fetal calf serum content of the medium could substantially reverse the growth inhibition. Thus, the plasma membrane of lymphoid cells contains a component that can slow or stop the growth of cells in culture. This membrane component may have a role in cell contact-mediated regulation of growth.

Effects of gonadectomy on seasonal changes in plasma LH and prolactin concentrations in male and female starlings (Sturnus vulgaris)

Intact and gonadectomized male and female starlings (Sturnus vulgaris) were held in outdoor aviaries for 1 year. Blood samples were taken frequently and assayed for LH and prolactin, and intact males were laparotomized to determine testis size. Changes in testis size in intact males were similar to those in wild starlings with maximum size during April. Hormone levels in intact males and females also followed a similar pattern to those in wild birds although absolute levels were somewhat lower. Levels of LH increased during spring, were highest in early May and then declined rapidly as birds became photorefractory. Prolactin levels did not begin to increase until April, reached a peak in late May and then declined. In gonadectomized males and females, high levels of LH were maintained throughout the early part of the year when birds were photosensitive, but declined rapidly as they became photorefractory. This occurred at the same time as in intact birds. During photorefractoriness, LH levels in gonadectomized birds were similar to those in intact birds. Prolactin showed the same seasonal pattern in gonadectomized birds as that in intact birds. These results demonstrate that gonadal steroid feedback is unimportant in initiating and maintaining photorefractoriness and confirm that increased prolactin secretion coincides with the onset of photorefractoriness.

Plasma corticosterone in wild starlings (Sturnus vulgaris) immediately following capture and in relation to body weight during the annual cycle

Free-living starlings (Sturnus vulgaris) were caught by mist netting. Blood samples were taken from them between 20 sec and 4 min after capture and assayed for corticosterone. Before 1 min corticosterone levels were constant (10.3 nmol litre-1) but after 1 min they increased rapidly (27.0 +/- 3.6 nmol litre-1 min-1). Male and female free-living starlings were caught throughout the year with mist nets, and traps placed in nest boxes. Blood samples were taken within 1 min of capture and body weights recorded. Plasma corticosterone varied between 3 and 13 nmol litre-1. In both sexes the level was high during winter and through the breeding season. It fell to low levels during late summer and increased again during autumn. Body weight in both sexes was highest in midwinter and lowest in midsummer but there was no correlation between body weight and plasma corticosterone concentration.

Plasma prolactin and gonadotrophins during gonadal development and the onset of photorefractoriness in male and female starlings (Sturnus vulgaris) on artificial photoperiods

Previous studies have shown that an increase in prolactin secretion coincides with the beginning of the photorefractory phase in starlings (Sturnus vulgaris). To determine how closely this increase is associated with the onset of refractoriness, we kept starlings on photoperiods which would induce refractoriness at different rates. Four groups of males and females were transferred from 8h light:16h darkness (8L:16D) to either 18L:6D, 13L:11D, 11L:13D or 8L:16D. Weekly blood samples were assayed for LH, FSH and prolactin and the males were frequently laparotomized to determine testis volume. In males, both 18L and 13L induced marked increases in plasma gonadotrophin levels and rapid gonadal maturation. A photoperiod of 18L induced an earlier onset of refractoriness (2-4 weeks) than 13L (6 weeks). In both cases prolactin levels began to increase immediately before the onset of refractoriness. Males on 11L showed a slight increase in gonadotrophin levels and slow gonadal maturation. There was no increase in prolactin levels and these birds did not become refractory. Hormonal data from the females were similar to those from males. These results confirm that increased prolactin secretion is associated, in some way, with the onset of photorefractoriness in this species, although whether it is a cause or consequence of photorefractoriness, or simply of gonadal regression, remains unclear.

An effect of nerve growth factor on parasympathetic neurite outgrowth

Addition of nerve growth factor (NGF) to dissociated parasympathetic ciliary ganglion neurons resulted, within 60 min of its addition, in a 2-fold increase in average neurite length and an accompanying enlargement and spreading of neuronal growth cones. These effects occurred over a concentration range of NGF of 0.1-10 ng/ml and were blocked by affinity-purified antibody to NGF. Epidermal growth factor, fibroblast growth factor, and angiotensin did not have these effects, although insulin at high concentrations was able to induce a response similar to that of NGF. Dissociated sympathetic chain neurons also responded to NGF with increased neurite lengths, and, in addition, NGF considerably extended the survival time of these neurons in culture. However, the effect of NGF on ciliary ganglion neurons was limited to neurite outgrowth, and NGF did not promote the survival of these parasympathetic neurons.

Equilibrium and kinetic studies of oxygen binding to fragments of Lymnaea stagnalis (freshwater snail) haemocyanin obtained by proteolytic digestion

Functional fragments of the haemocyanin from the gastropod mollusc Lymnaea stagnalis (freshwater snail) were obtained by partial digestion with trypsin and plasmin. The fragments were purified by ion-exchange chromatography and characterized by detergent/polyacrylamide-gel electrophoresis and crossed immunoelectrophoresis. Three types of single-functional unit fragment were isolated from the trypsin digest, and two immunologically distinct three-functional unit fragments and a single-functional unit fragment were isolated from the plasmin digest. The O2-binding behaviour of the fragments was investigated by equilibrium and kinetic methods. Over the pH range 7.0-8.2, in the presence of 10-20 mM-CaCl2, all of the single-functional unit fragments displayed non-co-operative O2 binding and showed no evidence of a Bohr or a salt effect. A Hill coefficient of less than 1.0 was obtained with one of the two three-functional unit fragments studied, whereas both of these fragments displayed a Bohr effect. Functional heterogeneity of the fragments was indicated by the variation in the O2 affinity, the P50 (partial pressure of O2 at half saturation) ranging between 0.26 and 0.77 kPa (approx. 2-6 mmHg). Stopped-flow data reflected the O2 equilibrium behaviour. Thus there was a fall in the value of the O2 dissociation rate constant from approx. 15 to 1s-1 in parallel with the increase in O2 affinity.

Plasma gonadal steroid levels in wild starlings (Sturnus vulgaris) during the annual cycle and in relation to the stages of breeding

Blood samples were collected from male and female free-living starlings in every month during the year and at all stages of the breeding cycle. The samples from females were assayed for oestradiol-17 beta, oestrone, and progesterone, and the samples from males were assayed for testosterone and 5 alpha-dihydrotestosterone. The testicular weights were recorded. All hormones other than oestrone showed a pronounced unimodal cycle. In females, oestradiol was highest in April, corresponding to the period of greatest nest-building activity. It decreased during the later stages of the breeding cycle and maintained low levels until the autumn when levels began to increase. Progesterone was highest in laying birds and reached a peak in May. During the rest of the year it remained at a lower but fairly constant level. Oestrone was normally only detectable in laying birds. In males, testicular weight and plasma concentrations of testosterone and 5 alpha-dihydrotestosterone were all highest during April. Plasma testosterone and 5 alpha-dihydrotestosterone were highest in nest-builders. They decreased during the later stages of breeding, remained low during the summer and increased slightly in the autumn. Testicular weight was high in nest-builders, but peaked during laying, by which time testosterone and 5 alpha-dihydrotestosterone had decreased significantly. Testicular weight decreased during incubation and feeding the young and remained low until the following year.

Equilibrium and kinetic studies of oxygen binding to the haemocyanin from the freshwater snail Lymnaea stagnalis

The binding of oxygen by the haemocyanin of the gastropod Lymnaea stagnalis was studied by equilibrium and kinetic methods. The studies were performed under conditions in which the haemocyanin molecule was in the native state. Over the pH range 6.8-7.6, in the presence of 10mM-CaCl2 the haemocyanin bound O2 cooperatively. Over this pH range the haemocyanin molecule displayed a normal Bohr effect whereby the O2 affinity of the molecule decreased with a fall in the pH of the solution. The maximum slope of the Hill plot (hmax.) was 3.5, obtained at pH 7.5. An increase in the CaCl2 concentration from 5 to 20 mM at pH 6.8 resulted in a slight increase in the oxygen affinity, with hmax. remaining virtually unchanged. At constant pH and CaCl2 concentration, an increase in NaCl concentration from 0 to 50 mM resulted in a small decrease in O2 affinity, but a significant increase in the value of hmax. from 3.5 to 8.6. Temperature-jump relaxation experiments over a range of O2 concentrations produced single relaxation times. The dependence of the relaxation time on the reactant concentrations indicated a simple bimolecular binding process. The calculated association and dissociation rate constants for this process at pH 7.5 are 29.5 X 10(6) M-1 X S-1 and 49 S-1 respectively. The association rate constant kon was found to be essentially independent of pH and CaCl2 concentration. The dissociation rate constant, koff, however, increased with a decrease in the pH, but was also independent of CaCl2 concentration. These results indicate that the stability of the haemocyanin-O2 complex is determined by the dissociation rate constant.

Conditioned medium increases the rate of neurite elongation: separation of this activity from the substratum-bound inducer of neurite outgrowth

Heart cell-conditioned medium supports extensive neurite outgrowth from dissociated parasympathetic neurons of the chicken embryo ciliary ganglion. We have shown previously that neurite outgrowth in this system depends on the deposition of a substratum-conditioning factor from conditioned medium onto the polyornithine culture substratum. However, in the presence of only the substratum-bound material, neurite outgrowth is never as extensive as in whole conditioned medium. The present report demonstrates that a different and soluble component of conditioned medium is required to achieve the rates of neurite elongation normally observed in whole conditioned medium. This second component, while unable by itself to support neurite outgrowth, is able to increase the rate of neurite elongation approximately 3-fold within 30 to 60 min of its addition. This conclusion is based on direct time-lapse observations of the rate of elongation of individual neurites before and after the addition of fractions of conditioned medium previously depleted of the substratum-conditioning factor. Correlated with the effect of such fractions of conditioned medium on the rate of neurite elongation is a change in the morphology of the growth cones, which become larger and more spread. The activity of the soluble, elongation-promoting component of conditioned medium is nondialyzable and is sensitive to treatments known to affect proteins, such as repeated freeze-thawing, heating, and trypsinization. Fractions of conditioned medium which contain the elongation-promoting activity also contain all of the survival factor for parasympathetic neurons previously shown to be present in heart cell-conditioned medium. The methods described here represent a convenient new assay which we have used recently to demonstrate elongation-promoting factors with neuronal specificity in extracts of rat hippocampus.

A comparison of the effects of labetalol, bendrofluazide and their combination in hypertension

1 Bendrofluazide (10 mg/day) or labetalol (300 mg and 600 mg/day) produced significant reductions in lying, standing, and post-exercise blood pressure in ten hypertensives. 2 Active treatments were approximately equivalent in anti-hypertensive effect. However, comparing lying and standing determinations, labetalol (600 mg/day) produced significantly greater additional postural falls in systolic blood pressure than during placebo or bendrofluazide treatment. 3 Systolic blood pressure rose after exercise during placebo or bendrofluazide treatment. However, on labetalol, mean changes in systolic blood pressure after exercise were negative and significantly different from those seen on placebo. 4 Greater reductions in lying and post-exercise systolic blood pressure were produced by combination treatment than by either individual drug. Additional postural and exercise-related falls in systolic blood pressure tended to be smaller with combination treatment than during treatment with labetalol alone. 5 Labetalol significantly reduced lying, standing, or post-exercise heart rate by comparison with placebo or bendrofluazide. 6 Labetalol significantly reduced lying, standing, or post-exercise heart rate by comparison with placebo or bendrofluazide. 6 Labetalol moderately reduced plasma renin activity, whereas bendrofluazide caused marked elevation. The effect of bendrofluazide predominated during combination treatment.

Electron spin resonance as a useful technique in the management of Hodgkin's disease

Electron spin resonance spectroscopy has proved a useful and simple technique for the measurement of levels of caeruloplasmin and iron transferrin in whole blood from 50 patients with Hodgkin's disease. Those patients with clinically active disease show higher caeruloplasmin levels and lower iron transferrin levels than those with inactive disease. The results indicate that these tests are good indicators of the state of the disease and that serial measurement of these parameters may help in early prediction of clinical reactivity and in monitoring response to treatment. The combined information from iron transferrin and caeruloplasmin levels appears to be more predictive than that from the erythrocyte sedimentation rate and neutrophil alkaline phosphatase score.

Electron spin resonance measurements of blood caeruloplasmin and iron transferrin levels in patients with non-Hodgkin's lymphoma

Caeruloplasmin and iron transferrin level were measured in blood of patients with non-Hodgkin's lymphoma in different stages of disease activity and compared with erythrocyte sedimentation rate and NAP level in the same samples. It was found that both caeruloplasmin level and sedimentation rate showed a slight increase in mean level in patients with active disease as compared with those in remission, particularly in the group of patients with poorly or undifferentiated diffuse disease. No difference was observed in levels of iron transferrin or NAP. Both caeruloplasmin and sedimentation rate showed occasional abnormal values in patients in remission but in most cases where both were elevated the patients subsequently entered a more active phase of the disease.

Cell kinetics of a chondrosarcoma

The cell kinetics of the transplantable DC-II mouse chondrosarcoma have been studied by the pulse labelled mitoses method. The analysis gave the following estimates for the phases of the cell cycle: G1, 10-5 hr; S, 9-5 hr; G2, 4 hr with an intermitotic time of 23-5 hr. Consideration of the overall growth of the tumour indicated that the growth fraction and cell loss factor both had values of about 0-5. The results are compared with cell kinetic data from sarcomas and other cartilage tissues.

Interrelations between ABO blood group, plasminogen, alpha1-antitrypsin, alpha2-macroglobulin and the platelet count in blood donors

The level of plasminogen alpha1-antitrypsin, alpha2-macroglobulin and the platelet count were measured in 511 blood donors. The mean level of alpha1-antitrypsin was significantly lower in men of group B compared with that of group O. No other differences between the blood groups reached statistical significance. Woman had higher mean levels of alpha1-antitrypsin and alpha2-macroglobulin and a higher platelet count than men. The levels of plasminogen and alpha1-antitrypsin were significantly higher in women using oral contraceptive compared with those who were not. The level of alpha2-marcoglobulin fell with age until the 60-64 year age-group in men and the 40-49 year age-group in women. A positive correlation existed between the alpha1-antitrypsin and the alpha2-macroglobulin level and between the platelet count and the plasminogen level.

Regional lung function in chronic pulmonary congestion with and without mitral stenosis

Relative regional ventilation and perfusion were measured with xenon-133 in 16 seated patients with pure or predominant mitral stenosis (group 1) and in 12 patients with chronic pulmonary congestion due to left-sided heart disease without mitral stenosis (group 2). The apex-base perfusion gradient was abnormally reduced and often reversed in group 1 patients. There was a significant negative correlation between perfusion gradient and mean pulmonary capillary pressure in both groups, but for a given elevation of pulmonary capillary pressure the perfusion gradient tended to be greater (i.e., less abnormal) in group 2. The regression line of perfusion gradient on pulmonary capillary pressure indicated that perfusion gradient had a value of zero (indicating reversal of the perfusion gradient) at a mean pulmonary capillary pressure of 26 mm Hg in group 2 but at only 18 mm Hg in group 1. Relative lower zone ventilation was abnormally reduced in group 1 and there was a significant negative correlation between ventilation gradient and pulmonary capillary pressure in group 1 but not group 2 patients. Comparison of the distribution of slowly inhaled small volume boluses, large volume boluses, and inspiratory capacity breaths of 133Xe suggested that the lower zone hypoventilation was due mainly to closure of peripheral airways but that selectively increased resistance and reduced compliance in the lower zones may contribute in some patients. Both ventilation and perfusion were reduced at the lung bases in group 1 patients, and between regions nonuniformity of relative ventilation/perfusion was significantly less than normal. Although ventilation distribution was relatively normal in group 2 patients, they also had significantly less regional ventilation/perfusion nonuniformity than normal subjects.