Alpha-tocopherol modulates genes involved in hepatic xenobiotic pathways in mice

Hepatic proteins involved in xenobiotic pathways (Phases I, II and III) are responsible for the metabolism and disposition of endogenous and exogenous compounds including dietary phytochemicals. To test the hypothesis that elevated alpha-tocopherol intakes alter gene expression of hepatic xenobiotic pathways, mice were fed diets supplemented with either 1000 IU (+E) or 35 IU (E) all-rac-alpha-tocopheryl acetate for 4 months; liver RNA was isolated, and gene expression was determined using both whole genome microarray and real-time quantitative polymerase chain reaction analyses. Hepatic alpha-tocopherol (173+/-18 vs. 21+/-1 nmol/g, mean+/-S.E.) and its metabolite (2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman, 0.232+/-0.046 vs. 0.031+/-0.019 nmol/g) concentrations were approximately eightfold higher following the +E dietary treatment. In +E relative to E mice, gene expression of Phase I enzymes, P450 oxidoreductase and cytochrome P450 3a11 increased 1.6- and 4.0-fold, respectively; two Phase II genes, sulfotransferase 2a and glutathione S-transferase mu 3, increased 10.8- and 1.9-fold respectively, and a Phase III biliary transporter, Abcb1a, doubled. Thus, consumption of high-level dietary alpha-tocopherol simultaneously coordinated Phase I, II and III gene expression. These data demonstrate that increased hepatic alpha-tocopherol modulates its own concentrations through increasing xenobiotic metabolism, a process that may alter metabolism of other foreign compounds, such as therapeutic drugs and phytochemicals, in humans.     

Individual differences in peripheral blood immunological and hormonal measures in adult male rhesus macaques (Macaca mulatta): Evidence for temporal and situational consistency

A growing body of research has indicated that consistent individual differences exist in physiological systems with which the immune system interacts. Few data have been reported that demonstrate stable individual differences in immunological measures, however. In the present study, enumerative measures of immune system activity were examined in 36 adult male rhesus macaques over a 13 month period under baseline conditions as well as under conditions of pharmacological and physical challenge. Blood samples were assayed for plasma concentrations of ACTH and cortisol, as well as neutrophil, total lymphocyte, CD4+ and CD8+ lymphocyte numbers, and the CD4/CD8 ratio. Analyses revealed that individual differences in the CD4/CD8 ratio and, to a lesser extent, plasma ACTH and cortisol concentrations, and neutrophil and CD4+ lymphocyte numbers were consistent across situations and times, despite changes in mean values during the various blood sampling sessions. The results suggest that the CD4/CD8 ratio might be considered trait-like and a useful immunological measure of biobehavioral organization. Am. J. Primatol. 44:29–41, 1998. © 1998 Wiley-Liss, Inc.     

Response of plasma endorphins, prolactin and catecholamines in women to intense heat in a sauna

Concentrations of immunoreactive beta-endorphin (ir beta-E), corticotropin, cortisol, prolactin and catecholamines in plasma were followed in 11 healthy women during and after exposure to intense heat in a Finnish sauna bath, and compared to those in a similar control situation without exposure to heat. Heat stress significantly increased prolactin and norepinephrine secretion; the percentage increases from the initial plasma concentrations varied from 113 to 1280% (mean 510%) and from 18 to 150% (mean 86%), respectively. The response of the plasma levels of epinephrine, ir beta-E, corticotropin and cortisol to heat exposure was variable. Compared to the control situation, no statistically significant effect of heat exposure on the plasma levels of these hormones was found.     

Expression of mast cell proteases correlates with mast cell maturation and angiogenesis during tumor progression

Tumor cells are surrounded by infiltrating inflammatory cells, such as lymphocytes, neutrophils, macrophages, and mast cells. A body of evidence indicates that mast cells are associated with various types of tumors. Although role of mast cells can be directly related to their granule content, their function in angiogenesis and tumor progression remains obscure. This study aims to understand the role of mast cells in these processes. Tumors were chemically induced in BALB/c mice and tumor progression was divided into Phases I, II and III. Phase I tumors exhibited a large number of mast cells, which increased in phase II and remained unchanged in phase III. The expression of mouse mast cell protease (mMCP)-4, mMCP-5, mMCP-6, mMCP-7, and carboxypeptidase A were analyzed at the 3 stages. Our results show that with the exception of mMCP-4 expression of these mast cell chymase (mMCP-5), tryptases (mMCP-6 and 7), and carboxypeptidase A (mMC-CPA) increased during tumor progression. Chymase and tryptase activity increased at all stages of tumor progression whereas the number of mast cells remained constant from phase II to III. The number of new blood vessels increased significantly in phase I, while in phases II and III an enlargement of existing blood vessels occurred. In vitro, mMCP-6 and 7 are able to induce vessel formation. The present study suggests that mast cells are involved in induction of angiogenesis in the early stages of tumor development and in modulating blood vessel growth in the later stages of tumor progression.     

Surface analysis and depth profiles of calcium in hepatoma cells during pyruvate-induced DNA synthesis

Induction of DNA synthesis is associated with increased uptake of calcium in cultured cells. Calcium distribution within the plasma membrane and adjacent cytoplasmic layers of hepatoma cells was investigated with X-ray photoelectron spectroscopy and oxygen plasma etching. Cells in minimal growth medium initiate active DNA synthesis 16 h after addition of sodium pyruvate. Cells stimulated with pyruvate and pyruvate-free controls were analysed by X-ray photoelectron spectroscopy--oxygen plasma etching at 0--40 A (layer I), 0--450 A (layer II) and 0--4000 A (layer III from the outer cell surface. Calcium concentrations were elevated in induced cells compared with controls: +20% in layer I, +60% in layer II, and +300% in layer III. As the plasma membrane is 90--120 A thick, these results indicate that pyruvate-induced DNA synthesis is preceded by an increase in calcium, most marked in the cytoplasm subjacent to the plasma membrane, moderate at its inner surface, and minimal at its outer surface.     

Catecholamine secretion from the adrenal medulla of the fetus, regulation by hormones

In the ovine fetus, the adrenal medulla activity secretes catecholamines into the circulation under normal and stress conditions. Little is known regarding the endocrine regulation of adrenal medullary catecholamine secretion in the fetus. The present study was undertaken to investigate the direct effects of the hormones prolactin, angiotensin II and cortisol on catecholamine release from fetal adrenal medulla, and to determine whether the effect of the hormones change during development into adulthood. Adrenal medulla from fetal, newborn and adult pregnant sheep was collected, dispersed into single cells and plated. Following preincubation, the cells were treated with ovine prolactin or angiotensin II at 8, 40 and 200 micrograms/ml; or cortisol at 10(-8), 10(-7) and 10(-6)M for 24 h. Catecholamine release into the medium were measured at 3, 6, 12 and 24 h. Ovine prolactin at 8 to 200 micrograms/ml significantly stimulated the release of total catecholamines after 12 h of incubation. The effect of prolactin was dose-dependent such that the magnitude of the response increased and the response time shortened with increasing concentrations of prolactin. In addition, the release of all three catecholamines--dopamine, norepinephrine and epinephrine--was significantly elevated. In newborn cells, only the highest concentration of 200 micrograms/ml ovine prolactin stimulated total catecholamine release at 6 h and 12 h, with significant increases of the three catecholamines at 12 h. In maternal cells, stimulation of catecholamine release was observed also with the highest concentration of prolactin tested (200 micrograms/ml) and after 12 h of incubation, when only the release of epinephrine was significantly enhanced by 324%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pituitary-adrenocortical and lymphocyte responses to bromocriptine-induced hypoprolactinemia, adrenocorticotropic hormone, and restraint in swine

A study was conducted with castrated male pigs (barrows) to evaluate effects of bromocriptine-induced hypoprolactinemia (6 days) on basal and adrenocorticotropic hormone (ACTH)-altered (single injection) pituitary-adrenocortical function, on lymphocyte proliferative responses, and on interleukin 2 production. In addition, the study was designed to measure the short time course of pituitary-adrenocortical and lymphocyte responses to ACTH and to a 30-min restraint stressor. Blood samples were taken via indwelling jugular catheters at -0.5, +0.5, +2, and +5 hr (with reference to time of acute treatment exposure) on Day 6 of the study. Lymphocyte responses were measured only at the 2-hr interval. Exposure (6 days) to bromocriptine (CB154) was associated with 53% reductions (P less than 0.05) in plasma prolactin (1.37 +/- 0.13 vs 0.60 +/- 0.04 vs 0.68 +/- 0.08 ng/ml) when averaged across all time intervals in control, CB154-treated, and CB154 + ACTH-treated pigs, respectively. The reductions in plasma prolactin were associated with a reduction (P less than 0.05) in basal plasma cortisol at only one time interval (+0.5 hr) when CB154-treated pigs were compared with controls (17.7 +/- 4.2 vs 26.9 +/- 3.2 ng/ml). CB154 had no effect on plasma ACTH or growth hormone concentrations for the time periods at which they were measured. CB154 treatment produced numerical, but not statistically significant, 38% reductions in interleukin 2 production (6.31 +/- 1.8 vs 3.91 +/- 1.47 units/ml). Lymphocyte proliferative responses to the mitogen concanavalin A and interleukin 2 production decreased 65 and 75% (P less than 0.05), respectively, 2 hr subsequent to ACTH administration when compared with control animals. Hence, under the conditions of this study, only a modest association between lowered plasma prolactin concentrations and basal cortisol concentrations was evident. The data suggest the absence of dopamine regulation of basal plasma ACTH in pigs and provide evidence for a rapidly occurring inhibitory effect of ACTH administration on specific lymphocyte activities.     

Different effects of aging on the opioid mechanisms controlling gonadotropin and cortisol secretion in man

The present study was undertaken in order to assess the influence of aging on the endogenous opioid control of gonadotropin and adrenocorticotropin/cortisol secretion in man. For this purpose, the capability of the opioid antagonist naloxone to increase circulating levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and cortisol was tested in male subjects of different ages. Thirty normal men were randomly chosen and divided into 3 groups by age: group I = 22-40 years (n = 10); group II = 41-59 years (n = 10); group III = 62-80 years (n = 10). Since the men of group III showed higher basal serum gonadotropin concentrations than the subjects of group I and group II, we selected from a large population a fourth group of elderly men with normal basal LH and FSH levels: group IV = 61-82 years (n = 7). All subjects were tested for 120 min during the intravenous administration of naloxone (4 mg given in an intravenous bolus at time 0, plus 10 mg infused for 2 h). Control tests with normal saline instead of naloxone were performed in all groups. All subjects had similar blood testosterone and cortisol levels, whereas LH and FSH concentrations were significantly higher in group III than in groups I, II and IV. Naloxone increased plasma cortisol concentrations by 50% in all groups. The cortisol secretory response followed a similar pattern regardless of age.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical, biological and hormonal study of mid-pregnancy termination in cats with aglepristone

In order to evaluate the efficacy, the safety and the variation in plasma concentrations of estrogens, progesterone, PGFM, oxytocin, cortisol and prolactin after mid-pregnancy termination induced by aglepristone, 61 pregnant queens (33.3 + 4.2 days), were injected subcutaneously with 15 [corrected] mg/kg aglepristone, (Alizine) [corrected] repeated once 24 h later. Five queens served as control and received a placebo. The efficacy of aglepristone was 88.5% and termination of pregnancy was achieved in 50% of the queens within 3 days. Brief periods of depression and anorexia were noted in 9.3% of the queens before fetal expulsion (these symptoms were attributed to the phenomenon of fetal expulsions). Not one of the queens that aborted developed uterine disease. There were no changes in plasma concentrations of estrogen, prostaglandin, prolactin or oxytocin following aglepristone administration. However, there were significant increases in plasma concentrations of progesterone and cortisol 60 and 30 h, respectively, after aglepristone administration. Termination of pregnancy occurred with high plasma progesterone concentrations. Fetal expulsion was characterised by an increase in estrogen, PGFM and oxytocin concentrations, whereas prolactin and cortisol levels remained at a basal level.     

The effects of carbon dioxide inhalation on plasma MHPG, plasma hormones respiratory rate, and behavior in the rhesus monkey

The effects of inhalation of air and 3 concentrations of carbon dioxide (CO2) on plasma levels of the norepinephrine metabolite, MHPG, plasma hormones, and behavioral activation were assessed in eight chair-adapted Rhesus monkeys (Macaca mulatta). In comparison to air, inhalation of 5%, 7.5% and 10% CO2 for 180 minutes produced significant dose-dependent increases in respiratory rate, plasma MHPG, cortisol, growth hormone and prolactin. CO2 at the 7.5% concentration produced peak changes in behavior at 15, growth hormone at 30, and cortisol and MHPG at 180 minutes without producing changes in prolactin. The lack of previously reported CO2 induced changes in MHPG, growth hormone and prolactin in humans exposed to 7.5% CO2 for only 15 minutes, may therefore relate to the relatively short duration of CO2 exposure.     

Roles of kisspeptin in IVF/ICSI-treated infertile women and in human granulosa cells

Kisspeptin, a crucial central regulator of reproduction, has been used as a trigger in in vitro fertilization (IVF) treatment. This study aimed to investigate the roles of kisspeptin in IVF treatment in infertile females (n = 30); and in steroidogenesis in human granulosa-like tumor cell line (KGN). In the human study, blood was collected at three time points including (1) the beginning of gonadotropin stimulation (Phase I), (2) around eight days after gonadotropin stimulation (Phase II), and (3) on the day of ovum pick-up (Phase III). Follicular fluid (FF) was collected at Phase III. Serum human chorionic gonadotropin (hCG) was measured 15 days after embryo transfer and fetal heart beats were determined around 42 days of menstrual cycle to classify the subjects into successful and unsuccessful groups. FF kisspeptin levels were higher in successful compared with unsuccessful subjects (P < 0.01). Kisspeptin levels were significantly higher in FF than in serum in successful subjects (P < 0.05) but were comparable in unsuccessful subjects. Serum kisspeptin was comparable among three phases in the successful group but its levels in Phase III were significantly lower compared with Phase I in the unsuccessful group (P < 0.01). Serum kisspeptin in Phase II/III had positive correlations with serum E2 in Phases II and III and the outcomes of IVF/intracytoplasmic sperm injection (ICSI) treatment including serum hCG levels. For the cell experiment (n = 3), kisspeptin treatment in the presence of FSH together with IGF-1 enhanced CYP19A1 (aromatase) mRNA expression compared with control. FSH alone increased aromatase concentrations in the supernatant compared with control and kisspeptin at the dose of 10^-2 mmol/L with FSH enhanced aromatase concentrations in the supernatant compared with FSH alone (P < 0.001 all). In conclusion, kisspeptin enhanced aromatase expression and secretion and was associated with positive outcomes of IVF/ICSI treatment. Further studies regarding supplementation of kisspeptin could reveal its beneficial effects on IVF/ICSI treatment.     

A longitudinal study of estrous cyclicity in aging C57BL/6J mice: I. Cycle frequency, length and vaginal cytology

Cycle frequency, length, and vaginal cytology were measured longitudinally in three cohorts of singly housed virgin mice staggered across a 3-year interval. The age profiles of these parameters were qualitatively similar, but quantitatively different, among cohorts. Cycle frequency was initially low (Phase I), due to prolonged cycles and late-starting cycles, and did not peak (Phase II) until mice were 3-5 months old. Phase II lasted for 7-10 months, depending on the cohort. Thereafter cycle frequency declined steadily (Phase III). The average age of cessation of cyclicity varied among cohorts, occurring between 13 and 16 months of age. Age changes in cycle length paralleled those of cycle frequency. During Phase II, median cycle length was less than 5 days and variance was lowest. During Phases I and III, variance was about twofold greater and median cycle length was greater than 5 days. Although median cycle length remained stable for several months during Phase II, the peak period of 4-day cycles was much shorter. In all cohorts, 4-day cycles did not peak until 7-8 months of age and began to decline by 9 months. The decrease in 4-day cycles was associated with a progressive lengthening of cycles-first from 4 to 5 days, then to longer cycles. The fraction of cycles with extended cornification (greater than 2 days) increased with advancing age from less than 0.35 during the initial period of cycle lengthening to a maximum of 0.60. The observation that the initial phase o cycle prolongation was not usually associated with extended cornification is consistent with earlier evidence that this period is characterized by a delayed, rather than prolonged, preovulatory rise of estradiol. However, the increased fraction of prolonged cycles with extended cornification at later ages suggests that the preovulatory elevation of estradiol may ultimately be prolonged.     

Vasopressor challenges during chronic MAOI or TCA treatment in anesthetized dogs

Ten male mongrel dogs were treated in Phase I with tranylcypromine, 6 mg/kg IM b.i.d., for 21 days. Dogs were anesthetized at weekly intervals before, during, and up to four weeks after drug treatment with a combination of amylbarbital, 25 mg/kg, 1% enflurane in 70:30 N₂0:0₂) and fentanyl, 500 mcg. Bolus IV injections of norepinephrine, 0.1–0.6 mcg/kg, and ephedrine, 0.03–0.12 mg/kg were given while continuously recording arterial blood pressure, lead II of the ECG, heart rate, and rectal temperature. Awakening times were noted. In Phase II, the dogs were given imipramine, 25 mg/kg IM b.i.d., for 21 days. During Phase III, 14 days of tranylcypromine, 7 days of tranylcypromine plus imipramine, and 7 days of imipramine were administered. Anesthetic techniques were repeated in phases II and III. The fourth phase consisted of tranylcypromine injections, 6 mg IM b.i.d., and anesthesia with amylbarbital 25 mg/kg, 2.5% enflurane in 70:30 N₂0:0₂. Vasopressor challenges were repeated during each phase of the study. Following induction of anesthesia and prior to fentanyl challenge, baseline blood pressures and heart rates did not differ from control in Phase I, II, and III of this study. Responses to norepinephrine during all of the tranylcypromine phases were not significantly different from control but ephedrine responses were prolonged, peaking by the second week of treatment. During Phase II, dysrhythmias occurred following norepinephrine and ephedrine with one lethality following norepinephrine, 0.2 mcg/kg. Responses to norepinephrine and awakening times were significantly greater during Phase II compared to Phase I. In Phase III, during the first week of combined therapy the responses to norepinephrine were significantly greater than any other week of this phase. During Phase IV, resting blood pressure and the ephedrine responses were significantly increased during tranylcypromine when the anesthesia regimen did not include fentanyl. These results suggest that during initial treatment with tranylcypromine or imipramine, cardiovascular responses to vasopressor challenges were predicted by the pharmacology of the antidepressant. During tranylcypromine phases, we did not observe exaggerated cardiovascular effects during anesthesia and vasopressor challenges as had been previously reported.

The use of monoamine oxidase inhibitors (MAOIs), alone or in combination with tricyclic antidepressants (TCAs), has been increasing over the last few years because they appear to be more effective than TCAs alone in treating resistant affective disorders. (1,2) However, reluctance to use MAOIs has persisted because of reports of interactions with various foods and drugs. (3–6) In recent years, cell membrane receptor studies have shown that chronic treatment (greater than 14 to 21 days) with either MAOIs of TCAs results in physiological adaptations that partially reduce the interactions between drugs and their receptors. (7,8) Attenuation of arrhythmogenicity has been described in dogs after six weeks of TCA treatment. (9) Clinically, patients on chronic MAOI therapy have undergone elective surgery, including open-heart surgery, without adverse responses. (10,11) The cardiovascular response to analgesics, anesthetics, and vasopressors during the initial phase (less than 14 to 21 days) of treatment with MAOIs compared to TCAs has yet to be addressed. Therefore, the purpose of this study was to examine the cardiovascular responses of analgesic, anesthetic, and vasopressor agents before, during, and after the first three weeks of MAOI and TCA administration in dogs.     

The sit-up: complex kinematics and muscle activity in voluntary axial movement.

This paper describes the kinematics and muscle activity associated with the standard sit-up, as a first step in the investigation of complex motor coordination. Eight normal human subjects lay on a force table and performed at least 15 sit-ups, with the arms across the chest and the legs straight and unconstrained. Several subjects also performed sit-ups with an additional weight added to the head. Support surface forces were recorded to calculate the location of the center of pressure and center of gravity; conventional motion analysis was used to measure segmental positions; and surface EMG was recorded from eight muscles. While the sit-up consists of two serial components, 'trunk curling' and 'footward pelvic rotation', it can be further subdivided into five phases, based on the kinematics. Phases I and II comprise trunk curling. Phase I consists of neck and upper trunk flexion, and phase II consists of lumbar trunk lifting. Phase II corresponds to the point of peak muscle contraction and maximum postural instability, the 'critical point' of the sit-up. Phases III-V comprise footward pelvic rotation. Phase III begins with pelvic rotation towards the feet, phase IV with leg lowering, and phase V with contact between the legs and the support surface. The overall pattern of muscle activity was complex with times of EMG onset, peak activity, offset, and duration differing for different muscles. This complex pattern changed qualitatively from one phase to the next, suggesting that the roles of different muscles and, as a consequence, the overall form of coordination, change during the sit-up.     

Hormonal and metabolic response to three types of exercise of equal duration and external work output

Five normal men, aged 20-30 years, participated in three types of exercise (I, II, III) of equal duration (20 min) and total external work output (120-180 kJ) separated by ten days of rest. Exercises consisted of seven sets of squats with barbells on the shoulders (I; Maximal Power Output Wmax = 600-900 W), continuous cycling at 50 rev X min-1 (II; Wmax = 100-150 W) and seven bouts of intermittent cycling at 70 rev X min-1 (III; Wmax = 300-450 W). Plasma cortisol, glucagon and lactate increased significantly (P less than 0.05) during the exercise and recovery periods of the anaerobic, intermittent exercise (I and III) but not in the continuous, aerobic exercise (II). No consistent significant changes were found in plasma glucose. Plasma insulin levels decreased only during exercise II. The highest increase in cortisol and glucagon was not associated with the highest VE, VO2, Wmax or HR; however it was associated with the anaerobic component of exercise (lactic acid). It is suggested that in exercises of equal duration and total external work output, the continuous, aerobic exercise (II) led to lowest levels of glucogenic hormones.     

Maternal reproductive hormone levels after repeated ACTH application to pregnant gilts

Prenatal stress has been seen as a reason for reproductive failures in pig offspring mostly originated or mediated by changed maternal functions. In pregnant gilts, three experiments (EXP I-III) were conducted to characterize the effects of repeated ACTH on maternal cortisol concentrations (EXP I) and on the secretion of maternal reproductive hormones (LH, progesterone, estrone sulfate; EXP II + III). Exogenous ACTH was given six times every alternate day beginning either on day 49 (EXP I + II) or day 28 (EXP III) of pregnancy. As a result of treatment, elevated cortisol levels were observed for more than 6 h (EXP I). Plasma concentrations of LH were at low basal level (0.1-0.2 ng/ml), but showed a pulsatory release pattern both during first and second trimester of pregnancy. The number of LH pulses/6 h (L.S.M. +/- S.E.) of saline treated controls increased with ongoing pregnancy (1.4 +/- 0.1 versus 2.0 +/- 0.2 in EXP III and EXP II, respectively). After ACTH treatment the number of LH pulses did not differ between the two gestational stages (1.3 +/- 0.2 and 1.4 +/- 0.2 in EXP III and EXP II, respectively). However, differences ( P < 0.05) were obtained comparing the LH pulse number of ACTH and saline treated sows during the second trimester of pregnancy. Moreover, areas under the curve (AUC) of each LH pulse and of all LH values over the baseline were significantly reduced by treatment. The levels of progesterone increased (P < 0.05) for 150-170 min after each ACTH application both in EXP II and EXP III. The concentrations of 17alpha-hydroxy-progesterone revealed likewise a significant elevation after each ACTH injection. Throughout EXP III, estrone sulfate concentrations were found to decrease (from 2.8-16.9 ng/ml on day 28 to 0.02-0.04 ng/ml on day 38) but without differences between ACTH-and saline-treated gilts. Further data of EXP II and EXP III, e.g. number of piglets born alive, confirmed the absence of detrimental treatment effects. Thus, repeated ACTH administration with subsequent release of cortisol is able to influence the release pattern of maternal reproductive hormones. However, these findings demonstrate that stress-related effects are dependent on the stage of pregnancy. The detected changes may affect feto-maternal interactions and, as a result, fetal reproductive development.     

Physiological changes associated with sporangiospore extrusion from trichospores ofSmittium culisetae

Trichospores of the fungus,Smittium culisetae (Trichomycetes), require a two-phase sequence of stimuli for sporangiospore extrusion: Phase I (20 mM KCl, pH 10) and Phase II (pH 7). Phases I and II correspond to conditions within the respective midgut and hindgut regions of mosquito larval hosts. In this study, trichospore pressure increased 1.0 MPa during Phase I but sporangiospores were not extruded. Potassium uptake was insufficient to account for the pressure increase. Sporangiospore extrusion from trichospores was stimulated by a drop in pH at Phase II. Lowering the osmotic potential of the Phase II solution with sucrose inhibited sporangiospore extrusion to varying degrees, with total inhibition occurring at osmotic potentials ≤ −2.7 MPa. At an osmotic potential of −2.1 MPa, the interwall layer at the trichospore apex swelled at the point of sporangial rupture without emergence of the sporangiospore. Interwall layer swelling during Phase II may rupture the sporangial wall of the trichospore and allow the sporangiospore to be extruded by its Phase I pressure.     

Emerging principles for the development of resistance to antihormonal therapy: implications for the clinical utility of fulvestrant

We seek to evaluate the clinical consequences of resistance to antihormonal therapy by studying analogous animal xenograft models. Two approaches were taken: (1) MCF-7 tumors were serially transplanted into selective estrogen receptor modulator (SERM)-treated immunocompromised mice to mimic 5 years of SERM treatment. The studies in vivo were designed to replicate the development of acquired resistance to SERMs over years of clinical exposure. (2) MCF-7 cells were cultured long-term under SERM-treated or estrogen withdrawn conditions (to mimic aromatase inhibitors), and then injected into mice to generate endocrine-resistant xenografts. These tumor models have allowed us to define Phase I and Phase II antihormonal resistance according to their responses to E₂ and fulvestrant. Phase I SERM-resistant tumors were growth stimulated in response to estradiol (E₂), but paradoxically, Phase II SERM and estrogen withdrawn-resistant tumors were growth inhibited by E₂. Fulvestrant did not support growth of Phases I and II SERM-resistant tumors, but did allow growth of Phase II estrogen withdrawn-resistant tumors. Importantly, fulvestrant plus E₂ in Phase II antihormone-resistant tumors reversed the E₂-induced inhibition and instead resulted in growth stimulation. These data have important clinical implications. Based on these and prior laboratory findings, we propose a clinical strategy for optimal third-line therapy: patients who have responded to and then failed at least two antihormonal treatments may respond favorably to short-term low-dose estrogen due to E₂-induced apoptosis, followed by treatment with fulvestrant plus an aromatase inhibitor to maintain low tumor burden and avoid a negative interaction between physiologic E₂ and fulvestrant.     

Increased seizure susceptibility and cortical malformation in beta-catenin mutant mice

Beta-catenin has been implicated in epilepsy because of its altered post seizure expression and the role of Wnt2 signaling in autism. To determine beta-catenin's role in seizure susceptibility, we injected penetylenetetrazol intraperitoneally in beta-catenin cerebral cortex- and hippocampus-specific knockout mice. We then analyzed the latency, number, and duration of four phases of seizure behaviors: (I) non-seizure activity, (II) myoclonic jerks, (III) generalized clonic seizures, and (IV) tonic seizures. The latencies to both death and Phase IV were significantly reduced in mutant mice. Mutant mice also spent significantly more time in Phases III and IV and showed significantly less time in the non-convulsive state (Phase I). Nissl and gold chloride staining indicated that the knockout mice had underdeveloped cortices, lacked a corpus callosum, and were missing hippocampal structures. This suggests that dysfunction of beta-catenin-mediated signaling pathways in mice leads to cortical malformation and increased seizure susceptibility.