Secondary Rise Research Articles

Effects of aconitine and batrachotoxin on Na currents and gating currents in the frog node of Ranvier

The effects of aconitine and batrachotoxin (BTX) on Na currents and gating currents were studied on voltage clamped frog nodes of Ranvier. The relation between steady-state values of charge movement and test pulse potential (Q-E) was compared with the fraction of open channels at a given potential (F-E). In aconitine-treated nodes the half potential, Emid, of the F-E curve was -87 mV and the slope factor, k, was 6.6 mV. Compared to normal nodes aconitine shifted the F-E curve by -53 mV along the voltage axis without significantly altering the slope. The parameters of the Qon-E curve of aconitine-treated nodes were Emid = -63 mV and k = 18.8 mV compared with Emid = -30 mV and k = 17 mV in a normal node. For the Qoff-E curve Emid was -76 mV, fairly close to Emid of the F-E curve, but the slope remained much smaller than that of the F-E curve. Thus, in aconitine-treated nodes, the normalized Qon-E and Qoff-E curves stay below the F-E curve over almost the whole potential range, a situation different from that in untreated or chloramine-T-treated nodes (Drews 1987). Similar results were obtained with BTX. The F-E curve of BTX-treated fibres had a half potential Emid = -85.1 mV and a slope factor k = 4.7 mV. In contrast to aconitine-treated nodes, the F-E curve showed a secondary rise at E greater than -50 mV.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose-induced early changes in cytoplasmic calcium of pancreatic beta-cells studied with time-sharing dual-wavelength fluorometry.

The cytoplasmic calcium concentration (Ca2+i) was measured in suspensions of fura-2-loaded mouse pancreatic beta-cells by recording the 340:380 nm fluorescence excitation ratio. Exposure to 20 mM glucose resulted in an initial reduction and later increase of Ca2+i irrespective of preincubation in medium containing 0.5 or 1.28 mM Ca2+ and 0 or 3 mM glucose. When elevating the Ca2+ concentration to 5 or 10 mM only 5 min before raising glucose to 20 mM, the sugar-induced reduction of Ca2+i became more pronounced like the subsequent increase. However, when the Ca2+ concentration was increased from 1.28 to 10 mM 2 min after stimulation with glucose, there was a sudden pronounced Ca2+i transient, which was followed by a decrease and a slower secondary rise. After preincubation in 20 mM glucose the glucose-induced initial reduction of Ca2+i was only seen in a Ca2+-deficient medium. Reintroduction of the sugar in the presence of extracellular Ca2+ resulted in an immediate rise of Ca2+i, the rapidity of which depended on the transmembrane Ca2+ gradient. The results emphasize the role of a saturable beta-cell pool of Ca2+ in glucose-induced reduction of Ca2+i and indicate that the first phase of insulin release depends on an influx of extracellular Ca2+.

Calcium and magnesium fluxes across the plasma membrane of the toad rod outer segment.

1. Membrane current was recorded from an isolated, dark-adapted toad rod by sucking either its inner segment or outer segment into a tight-fitting glass pipette containing Ringer solution. The remainder of the cell was exposed to bath solution which could be changed rapidly. 2. In normal Ringer solution the current response of a cell to a saturating flash or step of light showed a small secondary rise at its initial peak. The profile of this secondary rise (i.e. amplitude and time course) was independent of both the intensity and the duration of illumination once the light response had reached a plateau level. 3. This secondary rise disappeared when external Na+ around the outer segment was replaced by Li+ or guanidinium, suggesting that it represented an electrogenic Na+-dependent Ca2+ efflux which was declining after the onset of light. 4. This Na+-Ca2+ exchange activity showed a roughly exponential decline, with a time constant of about 0.5 s. Exponential extrapolation of the exchange current to the time at half-height of the light response gave an initial amplitude of about 2 pA. Using La3+ as a blocker, we did not detect any steady exchange current after the initial exponential decline. 5. An intense flash superposed on a just-saturating steady background light failed to produce any incremental exchange current transient. 6. Our interpretation of the above results is that in darkness there are counterbalancing levels of Ca2+ influx (through the light-sensitive conductance) and efflux (through the Na+-Ca2+ exchange) across the plasma membrane of the rod outer segment. The exchange current transient at the onset of light merely represents the unidirectional Ca2+ efflux which becomes revealed as a result of the stoppage of the Ca2+ influx, rather than a de novo Ca2+ efflux triggered by light. 7. Consistent with this interpretation, a test light delivered soon after a saturating, conditioning light elicited little exchange current, which then gradually recovered to control value with a time course parallel to the restoration of the dark current. Conversely, when the dark current was increased above its physiological level by IBMX (isobutylmethylxanthine) the exchange current transient became larger than control.(ABSTRACT TRUNCATED AT 400 WORDS)

Free-calcium and force transients during depolarization and pharmacomechanical coupling in guinea-pig smooth muscle.

1. Fura2 was loaded by permeation and hydrolysis of the acetoxymethyl ester into smooth muscle cells of intact thin sheets of the longitudinal layer of the small intestine of the guinea-pig, to record Ca2+ transients during contraction. 2. Cytoplasmic Ca2+ ([Ca2+]i) was monitored by computing the ratio of the fluorescence signal excited at 340 and 380 nm wavelengths. The dye loading and the exposure to UV light required for the experiments had no significant effect on the contractile parameters observed. 3. Spontaneous, rhythmic increases in [Ca2+]i were often observed, preceding the onset of force. Removal of extracellular Ca2+ caused a very transient increase in [Ca2+]i accompanied by a phasic force transient; this was followed by a decline in [Ca2+]i and tension below control levels. Elevated Ca2+ from 1.2 to 15 mM also caused a fall in [Ca2+]i and a relaxation of basal tension. 4. Elevation of [K+]o increased [Ca2+]i. Graded concentrations of K+ caused graded changes in both fluorescence ratio and tension. 5. Carbachol evoked a transient increase in [Ca2+]i and contraction. Thereafter, in spite of the continued presence of the drug, both signals declined, presumably as the result of cholinergic desensitization. The initial phasic force response to carbachol was usually followed by an 'after-contraction', that was only occasionally accompanied by a similar (small) secondary rise in the fluorescence signal. 6. In depolarized smooth muscle, both in the presence and in the absence of extracellular Ca2+, carbachol induced a transient increase in [Ca2+]i, indicating that Ca2+ release from intracellular stores is a major mechanism of pharmacomechanical coupling. 7. In some preparations an applied stretch caused, after a few seconds, a rise in [Ca2+]i and force development.

Delayed muscular rigidity and respiratory depression following fentanyl anesthesia.

A delayed effect of fentanyl used for anesthesia may be respiratory distress several hours after surgery. The findings are muscular rigidity, fall in chest wall compliance, hypoventilation, respiratory acidosis, and hypotension. In the past, to our knowledge, this complication was exclusively reported in patients undergoing cardiac surgery, when large fentanyl dosages are employed. This article describes three general surgical patients in whom respiratory distress developed three to five hours following colon surgery when a moderate dose of fentanyl citrate, 55 to 75 micrograms/kg, was used. Initially, all patients had a normal recovery from anesthesia. Later, respiratory distress was successfully treated with a fentanyl antagonist and ventilatory assistance. This delayed toxic phenomenon is thought to be due to the reentry of fentanyl into plasma from deposits in adipose tissue, muscle, and the gastrointestinal tract, leading to a secondary rise in the plasma concentration. It is more likely to be encountered when hypothermia, rewarming, and acidosis are present in the postoperative period. This life-threatening complication is treacherous, since it may occur when the patient has been transferred to the surgical ward and is less closely monitored.

Bradykinin stimulates a rise in cytosolic calcium in renal glomerular mesangial cells via a pertussis toxin insensitive pathway.

Bradykinin elicits a complex response in the renal glomerulus which includes a reduction in the glomerular capillary ultrafiltration coefficient. To elucidate the biochemical mechanism of this response, we investigated calcium signalling in rat renal glomerular mesangial cells in culture using the calcium-sensitive fluorescent dye, Indo-1. Bradykinin was found to cause a concentration-dependent transient rise in cytosolic free calcium followed by a sustained slower secondary rise. The bradykinin response persisted with acute removal of extracellular calcium using EGTA, indicating that calcium entry from outside the cell did not mediate this primary response. Prolonged exposure to EGTA, which reduced intracellular stores, eliminated the calcium response to bradykinin but not to vasopressin, indicating differential sensitivity to intracellular calcium stores of these two hormonal responses. In agreement, prior stimulation with vasopressin significantly attenuated the response to bradykinin, but the converse did not occur. Aluminum fluoride and pertussis toxin were used to investigate the possible involvement of a guanyl nucleotide regulatory protein in signal transduction. Aluminum fluoride induced a transient rise in cytosolic calcium that was abrogated by prior exposure of the cells to pertussis toxin. This demonstrates the effectiveness of pertussis toxin and the presence of a calcium-signalling pathway susceptible to pertussis toxin in these cells. In contrast, the responses to bradykinin and vasopressin were unaffected by pertussis toxin. We conclude that bradykinin stimulates release of calcium from intracellular stores in glomerular mesangial cells via a pertussis toxin insensitive pathway. This mesangial response provides a direct biochemical basis for the bradykinin-induced fall in glomerular capillary ultrafiltration coefficient which has been observed in vivo.

Neonatal and adult copper-64 metabolism in the pig and the possible relationship between the ontogeny of copper metabolism and Wilson's disease.

The copper profiles of neonatal mammals differ from those of the adult; in man they are similar to those found in people with Wilson's disease (WD). WD patients handle an intravenous bolus of radioactive copper in a characteristic manner which aids diagnosis. In view of the similarity between neonatal mammals and WD patients, we have studied the fate of an intravenous bolus of 64Cu injected into neonatal and adult pigs. In adult pigs, plasma 64Cu activity fell for 10 h and then slowly increased over the next 14 h as newly synthesised caeruloplasmin was secreted. In the neonate a secondary rise in 64Cu activity was not observed. Gel filtration of the soluble supernatant revealed significant differences in the association of 64Cu with hepatic copper proteins. In adults 64Cu associated predominantly with superoxide dismutase whilst in the neonate the 64Cu associated with metallothionein and a protein of high molecular weight. This study indicates that 64Cu export from the neonatal pig liver is in many ways similar to that found in WD. Additionally, there are similarities in the profile of hepatic 64Cu-binding proteins.

The Polyphasic Rise of Chlorophyll Fluorescence upon Onset of Strong Continuous Illumination: II. Partial Control by the Photosystem II Donor Side and Possible Ways of Interpretation

The fluorescence rise kinetics in saturating light display two well separated components with largely different properties. The rapid rise from F0 to a first intermediate level, I1 is photochemically controlled, while the following phases leading to a secondary intermediate level, I2 and to a peak level, P, are limited by thermal reactions. Treatments which primarily affect components at the photosystem II donor side are shown to increase quenching at I1 and/or to suppress the secondary fluorescence rise to I2. Preillumination by single turnover saturating flashes causes I1- quenching oscillating with period-4 in dependence of flash number. It is suggested that this quenching correlates with (S2 + S3) states of the watersplitting enzyme system. Suppression of the secondary, I1 - I2 rise component is invariably found with treatments which lower electron donation rate by the watersplitting system and are known to favor the low potential form of cyt b 559. Three different mechanisms are discussed on the basis of which donor-side dependent quench­ing could be interpreted: 1) Non-photochemical quenching by accumulation of the P 680+ radical cation. 2) Dissipative photochemical quenching at a special population of PS II centers (β- or non- B centers) displaying low donor capacity and high rates of charge recombination. 3) Dissipative photochemical quenching via cyclic electron flow around PS II, involving alternate donors to P 680+ (like cyt b 559 or carotenoid in their low potential forms), which can compete when donation rate from the water splitting system is slowed down. The possibility of donor-side limitation also being involved in “energy dependent” quenching is discussed.

Some Economics of Teaching

Adam Smith's discussion of the payment of teachers is reviewed in terms of industrial organization and agency theory. The implicit student fees necessary to support annual salaries average $1.30 per class meeting in primary and secondary schools and rise to $4.00 per lecture and up for college teachers. While salaries in teaching are much smaller than in the large-scale visual media, implicit valuations per contact hour in teaching are at least 600 times larger than in television. Classroom teaching is expensive because a teacher's scale of operations is sharply constrained by the student-teacher ratio.

Plasma concentration of factor VIII after administration of DDAVP of conscious dogs

The effect of the vasopressin analogue DDAVP on Factor VIII in plasma has been extensively studied in humans. To examine the effect of new and potentially better analogues a suitable animal model has to be established. In the present study trained Beagle dogs were injected with DDAVP and the time course of the Factor VIII response was monitored by a modification of the chromogenic substrate assay for Factor VIII. In most of the dogs DDAVP caused a biphasic increase of plasma concentrations of Factor VIII with an initial smaller increment within 10 min after the injection followed by a larger secondary rise after approximately 45 min. The average increase in Factor VIII was smaller than found in humans after comparable doses of DDAVP, and a few dogs responded very poorly. Despite these qualitative and quantitative differences it is concluded that trained dogs may serve as a useful model for testing the ability of other analogues than DDAVP to increase Factor VIII.

Mechanism of the hyperketonaemic effect of prolonged exercise in insulin-deprived type 1 (insulin-dependent) diabetic patients.

The effects of moderate exercise of 2-h duration on the concentration and turnover rate of total ketone bodies were assessed in 7 acutely insulin-deprived Type 1 (insulin-dependent) diabetic patients with an isotope tracer technique using a constant infusion of 14C-beta-hydroxybutyrate. These results were compared to those obtained in 13 normal control subjects in whom a similar range of hyperketonaemia (approximately 1-6 mmol/l) was induced by fasting. In all subjects, the concentration and the rate of production of ketone bodies followed a biphasic pattern with an initial fall lasting for about 20 min followed by a secondary rise. When integrated over the entire working period, the exercise-induced changes in ketone turnover were markedly dependent on the initial ketone body concentrations in both groups: at low ketonaemia (approximately 1 mmol/l), exercise increased the rate of production and disposal of ketones. These effects were progressively attenuated as basal ketonaemia rose and were reversed to an inhibitory action in markedly ketotic subjects (greater than 4 mmol/l). Despite the finding that, at high ketosis, exercise inhibited ketogenesis to a similar degree in control subjects and diabetic patients, the changes in concentration recorded at the end of exercise were different in the 2 groups: ketonaemia was reduced in fasted control subjects and increased in the diabetic patients. These data suggest that, contrary to a widely accepted opinion, the hyperketonaemic effect of prolonged exercise in ketotic diabetic patients does not result from an exaggerated stimulation of ketogenesis, but from some defect in their removal capacities for ketones, possibly related to insulinopenia.

Fever, Leucocytosis and C-reactive Protein after Open-Heart Surgery and Their Value in the Diagnosis of Postoperative Infections

The time course of body temperature (T), white blood cell count (WBC) and serum C-reactive protein (CRP) following uncomplicated open-heart surgery and the value of these three parameters in the diagnosis of postoperative infectious complications were analyzed in 153 patients. Preoperatively, all the patients had a normal T and the WBC level was under 10 X 10(9)/l. The CRP was elevated (over 20 mg/l) in five patients without having an influence on their postoperative courses. Postoperatively, T, WBC and CRP reached their maximum values during the first three days, decreasing gradually thereafter. Great individual variations in this average response to open-heart surgery were seen. Development of minor postoperative infections, mainly wound infection, (in 22 patients) were poorly reflected by these three parameters. However, a temperature exceeding 38 degrees C after the 6th postoperative day suggested presence of infection; less than 5% of patients without an infection had a temperature over this value. A secondary rise in CRP after the third postoperative day occurred in 20 patients and correlated well with postoperative complications; in 14 patients (70%) an infection became apparent, in three instances a probable infection was present, while two patients suffered from non-infectious complications. Only in one case (5%) did the cause for a secondary rise in CRP remain unknown. In major infections, i.e. mediastinitis, a CRP response occurred in all 12 patients, a temperature response in 11 patients (92%) and a WBC response in 10 patients (83%).

Arachidonic acid metabolism following aneurysm rupture evaluation of cerebrospinal fluid and serum concentration of 6-keto-prostaglandin F 1α and thromboxane B 2 in patients with subarachnoid hemorrhage

Experimental investigations have suggested an important role of arachidonic acid metabolites in the genesis of cerebral vasospasm following subarachnoid hemorrhage. In this clinical study the cerebrospinal fluid (CSF) and serum levels of the two main arachidonic acid metabolites prostacyclin and thromboxane A 2 are evaluated by measuring their stable degradation products 6-keto-prostaglandin F 1α (6-keto-PGF 1α) and thromboxane B 2 (TXB 2) using radioimmunoassay methods during the pre- and postoperative course in patients after aneurysm rupture. Although the serum levels of both substances do not seem to be important for the clinical course of the patients, the CSF concentrations of 6-keto-PGF 1α and TXB 2 provide important data. A close correlation between the initial TXB 2 level of the individual patient and the amount of blood in the basal cisterns as detected by computed tomography scan can be demonstrated. The predictive value of this additional information for the occurrence of cerebral angiospasm is discussed. Comparing the CSF levels of both metabolites the slight preoperative elevation of 6-keto-PGF 1α is significantly surmounted by an extraordinary rise in TXB 2 concentration. Postoperatively, after cleavage of the basal cisterns there is a decline in the CSF levels of both substances. The pre- and postoperative clinical course in comparison to the CSF levels of 6-keto-PGF 1α and TXB 2 is demonstrated in four patients. A nearly normal course of TXB 2 and 6-keto-PGF 1α seems to be associated with an uneventful clinical course, whereas a high TXB 2 level—whether occurring preoperatively or, even more important, as a secondary postoperative rise—seems to be associated with ischemic complications and neurological deterioration. It is suggested that pre- and post- operative monitoring of CSF levels of 6-keto-PGF 1α and especially TXB 2 may serve as a possible indicator for the detection of patients at risk of developing cerebral vasospasm.

The role of gonadal steroids in feedback regulation of gonadotropin secretion at different stages of primate development.

The serum gonadotropin response to castration was assessed in 8 foetal, 2 neonatal, 30 juvenile, and 2 adult rhesus monkeys (M. mulatta). In the 30 castrated juvenile monkeys and 8 sham-operated controls, concentrations of oestrone, oestradiol, androstenedione, dihydrotestosterone, testosterone and 17OH-progesterone were measured in 10 ml serum pools before, one month after, and one year after the surgical procedure. Castration during foetal life (83-137 days gestation) was followed within 48-72 h by a significant rise in serum FSH levels in males, but had no effect on the already high levels in females. Similarly, castration of males during the first post-natal month raised serum FSH and LH into the adult castrate range; however, after 3 months of age serum gonadotropin levels again declined to the normal juvenile range in spite of the open feedback loop. Orchiectomy of prepubertal juvenile monkeys (age 3 month-2 8/12 years) had no immediate effect on serum gonadotropins, but was followed by a delayed rise in FSH (at age 2 3/12-4 3/12 years) and LH (at age 2 7/12-4 4/12 years) to adult castrate levels. Orchiectomy of older prepubertal (by serum testosterone) or adult males resulted within a few days in a progressive and sustained rise in serum FSH and a more gradual rise in LH. Prepubertal gonadotropin regulation appeared to be sexually dimorphic, since ovariectomy in juvenile females (age 3 months-1 5/12 years) was followed by generally elevated, if somewhat erratic, serum FSH values, with a secondary rise in both FSH and LH levels at 2-2 1/12 years. In both sexes, prepubertal castration caused a significant and sustained decline in serum concentrations of oestradiol; castrated males also showed a decline in serum testosterone levels. Although prepubertal castration also caused in both sexes a slight decline in serum oestrone, and ovariectomy a decline in serum androstenedione and dihydrotestosterone, these effects were not sustained one year later, and values were not significantly different from sham-operated controls. Taken together, these data lend support to a model of primate sexual maturation in which the primary regulator of gonadotropin secretion in both sexes during the prolonged juvenile phase is central inhibition of the hypothalamic GnRH regulator. However, during foetal and neonatal life, and again following the onset of puberty, the major modulator of gonadotropin secretion becomes sex steroid-mediated feedback inhibition.

Human anti-estrogen receptor antibodies: assay, characterization, and age- and sex-related differences.

A binding assay was developed to measure the estrogen receptor (ER)-binding activity in serum. The method employed immunoglobulin G (IgG) adsorption with protein A-bearing Staphylococcus aureus cells before incubation with tritium-labeled ER. Specificity studies employing chromatographic and electrophoretic analyses suggested that an IgG antibody (Anti-ER) was responsible for the serum activity. Anti-ER was found in human, rat, and mouse serum and exhibited species cross-reactivity. The antibody recognized both the 8S and 5S forms of the ER. Anti-ER was measured in 262 individuals ranging in age from 1-85 yr. The antibody was detected in all serum samples examined, suggesting its natural occurrence. When the study group was divided into three arbitrary age groups (young, 1-13 yr; middle age, 13-51 yr; older, greater than 51 yr), significant differences in levels of antibody were found, with highest levels in the young, followed by the elderly, and lowest levels in the middle years. An examination of sex- as well as age-related differences in the population revealed a striking sex difference. Thus, the young male population had a lower level of antibody than the corresponding female population, and these levels in males declined throughout life to reach their lowest point in old age, whereas the high levels in young females declined in middle years and then increased significantly in the elderly. We postulate that the antibody is a subgroup of IgG of multifactorial etiology. The idiotypic network theory offers an explanation for the occurrence of these antibodies in normal serum, whereas an autoimmune mechanism could account for the secondary rise of anti-ER in the aging female population.

Endometrial blood flow measured by xenon 133 clearance in women with normal menstrual cycles and dysfunctional uterine bleeding

Endometrial blood flow was measured through the menstrual cycle in nonpregnant women (28 studies of 17 women with normal menstrual cycles and 32 studies of 20 women with dysfunctional utenne bleeding) with use of a clearance technique in which 100 to 400 μCi of the γ-emitting isotope, xenon 133 in saline solution was instilled into the uterine cavity. The mean (±SEM) endometrial blood flow in normal cycles was 27.7 ± 2.6 ml/100 gm/min, with a significant elevation in the middle to late follicular phase, followed by a substantial fall and a secondary slow luteal phase rise that was maintained until tho onset of menstruation. There was a significant correlation between piasma estradiol levels and endometrial blood flow in the follicular but not the luteal phase. Blood flow parterns in women with ovulatory dysfunctional bleeding were similar to normal, except for a significantly lower middle follicular rate. Women with anovulatory dysfunctional bleeding exhibited exceedingly variable flow rates.

Impaired hepatocellular integrity during general anaesthesia, as assessed by measurement of plasma glutathione S-transferase

The measurement of plasma glutathione S-transferase (GST) concentrations have been used to assess the changes in hepatocellular integrity which occur following general anaesthesia. Of 20 selected patients, who received halothane for minor urological procedures, 16 showed a small transient rise in GST between 1 h and 3 h after anaesthesia. Similar changes were also observed in 8 consecutive patients who received halothane for various operative procedures. In 3 of these 28 patients a marked secondary rise in plasma GST was observed 24 h after anaesthesia. No significant changes in ALT were observed in either of the groups of patients. These data indicate two possible phases of hepatotoxicity following halothane administration which results in a transient impairment in hepatocellular integrity in the majority of patients who undergo anaesthesia with this agent.

Antibody response of mice to lactate dehydrogenase-elevating virus during infection and immunization with inactivated virus

BALB/c and Swiss mice were infected with lactate dehydrogenase-elevating virus (LDV) or immunized with glutaraldehyde-inactivated or ether-extracted virus and their plasma was monitored for anti-LDV IgG and IgM levels by ELISA and indirect fluorescent antibody staining, for neutralizing antibodies, for sensitized antibody-virus complexes, for immune complexes, and for total plasma IgG and IgM. In infected mice, anti-LDV IgM was transiently formed during the first 2 weeks post infection (p.i.) but only at a low level. Anti-LDV IgG was produced in a biphasic manner with an initial peak at about 10 days p.i. and a secondary rise reaching a maximum level 30–80 days p.i. which was retained throughout the persistent phase of infection. The concomitant appearance of comparable levels of low molecular weight immune complexes suggests that most anti-LDV IgG was complexed with LDV proteins. Also, as early as 10 days p.i., infectious antibody-LDV complexes developed, which were neutralizable by rabbit anti-mouse IgG, whereas antibodies that neutralize the infectivity of exogenously added LDV appeared only 1–2 months p.i. Throughout infection, most of the anti-LDV IgG was directed to VP-3, the envelope glycoprotein of LDV, which was found to exist in at least 10 distinct forms ranging in molecular weight from 24 to 42 kDa. Anti-LDV IgG levels as high as those observed in infected mice developed in mice immunized with inactivated LDV. Antibodies to glutaraldehyde-inactivated LDV were also mainly directed to VP-3, but exhibited no neutralizing activity. The polyclonal B cell activation associated with a persistent LDV infection and the formation of immune complexes were not observed in mice immunized with inactivated virus.

Annual cycle of plasma thyroid hormone levels in the toad, Bufo japonicus

Plasma thyroxine (T4) of the toad, Bufo japonicus formosus, was monitored monthly from March, 1981 to February, 1982. Toads were captured at Sayama, Saitama Prefecture, and individual blood samples were collected from the heart soon after capture in the field. The plasma T4 levels were minimal in November for males (0.096 ng/ml) and in December for females (0.038 ng/ml). Levels increased during the resting stage in winter and reached a peak in March, about 1 week before the breeding migration, in both males (0.48 ng/ml) and females (0.66 ng/ml). After breeding occurred in early April, the T4 levels fell rapidly to nearly the minimum in females (0.088 ng/ml) and to an intermediate level in males (0.26 ng/ml). During summer, the T4 levels were low (between 0.1 and 0.3 ng/ml) but were significantly higher than the minimum in both sexes. Males showed significantly higher T4 levels than females in January. April, October, and December. Changes in plasma T4 levels around the breeding period were studied in greater detail with toads collected in March at Shiki, Saitama Prefecture. Extremely high levels of T4 (1.72 ng/ml) were detected in both male and female toads collected in the breeding pond, showing a secondary rise of the T4 level at arrival at the breeding pond. Plasma triiodothyronine (T3) levels followed patterns similar to those of T4, although the concentrations of T3 were extremely low (between undetectable level and 116 pg/ml). The initial rise of the thyroid hormone level in winter may be related to energy metabolism at the low temperature. The secondary rise of thyroid hormone in the pond may be related additionally to the vigorous muscular activity in cold water. Roles of thyroid hormone in the initiation of the migratory movements to and from the breeding pond were also considered.

Uterine prostaglandin and blood flow responses to estradiol-17β in cyclic cattle

Normal cyclic dairy cattle (n=7) underwent a midventral laparotomy on day 17 of the estrous cycle and were fitted, ipsilateral to the CL, with: an electromagnetic flow transducer around the uterine artery (UA; n=5); catheters within the ovarian vein (OV; n=7) via a uterine branch of the ovarian vein, uterine branch of the ovarian artery (UBOA; n=5) and facial artery (FA; n=7). On day 18, blood samples were collected at 30 min intervals for 1 h prior to injection of estradiol-17β (E 2; 3 mg) and 12 h post-E 2. Uterine blood flow (UBF) was monitored continuously and plasma samples analyzed for PGF 2α and PGFM. Exact locations of catheters in reproductive tracts were verified post-slaughter. Data were analyzed by method of least squares analysis of variance. Uterine blood flow (ml/min) increased above pre-E 2 flow rates within 30 min post-E 2 injection, peaked between 2.5 to 3.5 h and declined between 4 to 8.5 h. A small secondary rise in UBF occurred between 9 and 12 h. Regression analysis for concentrations (pg/ml) of PGF 2α and PGFM in the OV (i.e., [OV]-[FA]) demonstrate a similar response as PGFM concentration in the FA in that all increased at approximately 3 h, peaked between 5 and 7 h and returned to near baseline levels by 9 to 10 h post-E 2. Facial artery PGFM concentrations were positively correlated with uterine production of PGF 2α (r=.66) and PGFM (r=.30), whereas FA PGF 2α concentrations were not. In three of five cows, a difference in PGF 2α was detected between UBOA and FA (UBOA > FA); supportive of a local countercurrent exchange between the uterine venous drainage and the ovarian artery.