Serum melatonin kinetics and long-term melatonin treatment for sleep disorders in Rett syndrome

We studied the circadian rhythm of serum melatonin levels in two patients with classical Rett syndrome having severe sleep disorders; serum melatonin levels were measured before and during melatonin treatment using radioimmunoassay. Patient 1 had a free-running rhythm of sleep-wake cycle from 3 years of age. At the age of 4 years, the peak time of melatonin was delayed 6 h compared to normal control and the peak value was at the lower limit. Patient 2 had a fragmented sleep pattern accompanied by night screaming from 1 year and 6 months of age. At the age of 10 years, the peak time of melatonin secretion was normal but the peak value was at the lower limit. These patients were given 5 mg melatonin orally prior to bedtime. Exogenous melatonin dramatically improved the sleep-wake cycle in patient 1. In patient 2, exogenous melatonin showed a hypnotic effect but early morning awakenings occurred occasionally. When melatonin treatment was stopped, the sleep disorders recurred and re-administration of 3 mg melatonin was effective in both patients. The effect was maintained over 2 years without any adverse effects. These findings suggests that sleep disorders in patients with Rett syndrome may relate with an impaired secretion of melatonin.

Fatty acid composition and arachidonate metabolites in the livers of ethanol-treated rats fed an arachidonate-supplemented diet: effect of dietary fat

The effects of 1% arachidonic acid ethyl ester (AA) administration on the liver prostanoid metabolites and on serum and liver lipids in 3 g/kg ethanol-administered rats fed 10% lard or corn oil were studied. The rats were divided into 6 groups: lard-sucrose (Lard-Suc); lard-ethanol without AA (Lard-Et); lard-ethanol with AA (Lard-EtAA); corn oil-sucrose (Corn-Suc); corn oil-ethanol without AA (Corn-Et); and corn oil-ethanol with AA (Corn-EtAA). Liver triglyceride increased in Corn-EtAA compared with Corn-Et. Arachidonic acid (20: 4n-6) levels in liver phospholipid were significantly decreased in Corn-Et, but elevated in Lard-Et. The levels of 20:4n-6 were significantly increased with AA administration in both ethanol groups. Liver 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in Corn-Suc (24.7 +/- 5.1 pg/mg protein) was markedly higher than in Lard-Suc (4.5 +/- 1.2 pg/mg protein), and the 6-keto-PGF1 alpha lowered significantly with the addition of ethanol (9.3 +/- 0.9 pg/mg protein), but it increased with AA administration (21.6 +/- 4.9 pg/mg protein). In Lard-EtAA, a significant increase in 6-keto-PGF1 alpha was observed compared with Lard-Suc. The liver leukotriene B4 (LTB4) level in Lard-Suc was significantly lower than that of Corn-Suc. In the corn oil group, ethanol feeding was associated with a significant increase in liver LTB4. AA administration to Corn-Et suppressed the elevated LTB4. Serum thiobarbituric acid-reactive substance (TBARS) concentrations in the corn oil group were higher than in the lard group, and these concentrations were not altered by AA administration. From these results, we concluded that the administration of AA in rats treated with ethanol increased 20:4n-6 in liver phospholipid and liver PGI2 levels, irrespective of dietary fat, and may protect against alcoholic liver injury. AA with a diet rich in linoleic acid (18:2n-6), however, may increase fat in the alcoholic liver.

Comparative myocardial depression of sevoflurane, isoflurane, and halothane in cultured neonatal rat ventricular myocytes

In this study, we compared the direct myocardial depressant effects of sevoflurane, isoflurane, and halothane and determined whether an L-type Ca2+ channel agonist, Bay K 8644, could attenuate the myocardial depression induced by these anesthetics in cultured neonatal rat ventricular myocytes. Ventricular myocytes were obtained from neonatal rats by enzymatic digestion with collagenase and then cultured for 6-7 days. The myocytes were stabilized in serum-free medium, and the spontaneous beating rate and contractile amplitude were measured by using a fiberoptic sensor. Each anesthetic decreased the beating rate and amplitude in a concentration-dependent manner (1%-4% vol/vol) (P < 0.001), with halothane decreasing the beating rate and amplitude the most (P < 0.01). Isoflurane caused larger decreases in the beating rate than sevoflurane at 3% and 4% (P < 0.05). Potency for suppression of contractile amplitude was in the order of halothane > > isoflurane > sevoflurane. However, the myocardial depressant effects of the anesthetics were not different when their concentrations were corrected for minimum alveolar anesthetic concentration values. Bay K 8644 significantly prevented the anesthetic-depressed amplitude (P < 0.05). We conclude that sevoflurane, isoflurane, and halothane have direct myocardial depressant effects on cultured neonatal rat ventricular myocytes and that the reduction of sarcolemmal L-type Ca2+ channel current levels mediates the myocardial depression observed in these immature hearts.

IMPLICATIONS

Sevoflurane, isoflurane, and halothane have a direct cardiodepressant effect on cardiac excitation-contraction coupling in the immature heart, which is mediated by an interaction with the L-type Ca2+ channel.

Role of nitric oxide production through M2-cholinergic receptors in cultured rat ventricular myocytes

We previously reported that carbachol (CCh) caused the enhancement of NO production coinciding with negative chronotropy in cultured rat ventricular myocytes. In this study, we examined which subtype of muscarinic cholinergic receptor mediated these effects of CCh by measuring the NOx production with an HPLC-Griess reaction system and monitoring the beating with a Fotonic Sensor. The enhancement of NO production and negative chronotropy by 10(-4) M CCh stimulation were significantly inhibited by 10(-6) M atropine, 10(-6) M methoctramine, 3 x 10(-4) M L-NMMA, and 10(-5) M methylene blue. On the other hand, 10(-6) M pirenzepine and 10(-6) M HHSiD had no influence on the negative chronotropy by 10(-4) M CCh stimulation. Both 10(-6) M pirenzepine and 10(-6) M HHSiD suppressed the enhancement of NO production by 10(-4) M CCh stimulation slightly though not statistically. In addition, the m2 cholinergic receptor gene was expressed in our cell preparations, as demonstrated by reverse-transcriptase/PCR analysis. We concluded that M2-cholinergic receptor-mediated negative chronotropy may be due in part to activation of the NO-signaling pathway in cultured rat ventricular myocytes.

Establishment and characterization of pro-B cell lines from motheaten mutant mouse defective in SHP-1 protein tyrosine phosphatase

Mice homozygous for the motheaten (Hcph(me)) mutation lack a functional SHP-1 protein tyrosine phosphatase, show severe immunologic dysregulation and die at an early age. Severe pneumonitis in me/me mice is associated with abnormal proliferation of macrophages and granulocytes. Overgrowth of macrophages in long term cultures of me/me bone marrow has prevented analyses of lymphopoiesis in vitro. To establish hematopoietic cell lines from me/me mice, we cultured me/me bone marrow with the PA6 stromal cell line in the presence of antagonistic antibody against the receptor (c-Fms) for macrophage colony stimulating factor (M-CSF). In these cultures, overgrowth of M-CSF-dependent macrophages was suppressed by the antagonistic antibody and other hemopoietic cell lineages were generated efficiently from me/me bone marrow. By using this culture system, we established me/me pro-B cell clones (MEBs) with rearranged DH-JH but not VH-DJH. The growth of MEB clones required IL-7 and c-Kit ligand, corresponding to normal pro-B cells which express SHP-1. MEB cells were sensitive to starvation by either IL-7 or c-Kit ligand, resulting in apoptotic death. The present culture system, which supports hematopoiesis of me/me bone marrow, provides useful tools for the determination of the role of SHP-1 in signal transduction of B lymphopoiesis.

Effects of neonatal hypoxia on the medulla-spinal cord descending neurons

Hypoxic changes in the medulla-spinal cord descending neurons were studied morphologically using a retrograde neurotracer, choleratoxin B subunit (CTb). On postnatal day 7, Sprague-Dawley rats were subjected to a hypoxic load of 8% oxygen for 5 hours. In the rats that survived, CTb was injected into the lumbar enlargement at postnatal day 26, and they were killed at postnatal day 28 for histologic analysis. Retrograde transported CTb was visualized by immunohistochemistry. The results were compared with those obtained from control rats. In the control rats, CTb-positive cells were observed in the nucleus reticularis gigantocellularis, nucleus reticularis magnocellularis, nucleus raphe magnus, nucleus raphe obscurus, and nucleus raphe pallidus. In the hypoxic rats, although CTb-positive cells were detected in the same areas as the control rats, there was a noteworthy decrease in the number of CTb-positive cells in all areas, and there were many cells with hypoxic degeneration. In all of the nuclei a marked decrease in the number of CTb-positive cells was observed. Because medulla-spinal cord descending neurons have important roles in the regulation of postural muscle tone, these results may account for the pathophysiology of abnormal muscle tonus accompanying hypoxic brain damage.

Femtomolar bradykinin-induced relaxation of isolated bovine coronary arteries, mediated by endothelium-derived nitric oxide

We reported previously that bradykinin induces endothelium-dependent relaxation at nanomolar (nM) concentrations in isolated bovine coronary arteries with an intact endothelium. Recently we have found that in the presence of 10 microM indomethacin, femtomolar (fM) concentrations of bradykinin induce endothelium-dependent relaxation in some bovine coronary arteries (approximately 10% of the coronary arteries examined). The present study was designed to characterize the relaxation induced by fM bradykinin. Relaxation was completely abolished by repeated application of fM bradykinin, by 100 microM N(omega)-nitro-L-arginine methyl ester and by 10 microM methylene blue. Relaxation induced by nM bradykinin was partly affected by these treatments. Relaxation induced by both concentrations of bradykinin was inhibited by a B2-kinin receptor antagonist, [Thi5,8, D-Phe7]-bradykinin, in a concentration-dependent manner, but not by a B1-kinin receptor antagonist, des-Arg9, [Leu8]-bradykinin. In the presence of 10 microM captopril, an angiotensin-converting enzyme (ACE) inhibitor, all coronary arteries examined in this experiment showed endothelium-dependent relaxation to fM bradykinin. These results show that some bovine coronary arteries relax in response to fM bradykinin, and this response is mediated predominantly by the release of nitric oxide via stimulation of endothelial B2-kinin receptors. The relaxation may be dependent on ACE activity.

Local release of steroid hormones, prostaglandin E2, and endothelin-1 from bovine mature follicles In vitro: effects of luteinizing hormone, endothelin-1, and cytokines

Local regulation of ovulation involves the interaction of LH and intrafollicular factors including steroids, prostaglandins, and peptides derived from endothelial cells, leukocytes, fibroblasts, and steroidogenic cells. To estimate the intrafollicular role of endothelin-1 (ET-1) and its possible interaction with LH, tumor necrosis factor alpha (TNFalpha), and interleukin-1beta (IL-1beta), a microdialysis system was implanted into the theca layer of preovulatory bovine follicles that were maintained in organ culture chambers. The effects of LH, ET-1, TNFalpha, and IL-1beta on the local release of steroids, prostaglandin E2 (PGE2), and ET-1 from the cells surrounding the implanted capillary membrane were investigated. Each preovulatory follicle (selected based on the concentrations of steroids and PGE2) was dissected from surrounding stromal tissue and implanted with 4 capillary dialysis membranes (control, LH, cytokines or ET-1, and LH+cytokine or LH+ET-1) into the theca layer. They were then incubated in organ culture chambers and perfused with Ringer's solution for 14 h after pre-perfusion for 2 h. The stimulation with LH (5 microg/ml) between 4 and 6 h increased the release of progesterone (P4), androstenedione (A), estradiol-17beta (E2), PGE2 (p < 0.001), and ET-1 (p < 0.05). The infusion of ET-1 (250 ng/ml) between 8 and 10 h inhibited P4 and A release but stimulated E2 release (p < 0.05). The infusion of TNFalpha (100 ng/ml) between 8 and 10 h after LH exposure suppressed the release of A and E2 (p < 0.05). IL-1beta (10 ng/ml) between 8 and 10 h stimulated E2 release but inhibited A release (p < 0.05). Moreover, ET-1 and cytokines clearly stimulated PGE2 release (p < 0.05). ET-1 and TNFalpha induced further release of PGE2 stimulated by LH (p < 0. 05). Also, TNFalpha and IL-1beta induced further release of ET-1 stimulated by LH (p < 0.05). These results show that ET-1 is released from the theca layer of mature bovine follicles in vitro and that it affects follicular steroids and PGE2 secretion. The overall results suggest that interactions among ET-1, PGE2, and cytokines may have key roles in a local intermediatory/amplifying system of the LH-triggered ovulatory cascade in the bovine preovulatory follicle.

Transgene expression of steel factor in the basal layer of epidermis promotes survival, proliferation, differentiation and migration of melanocyte precursors

Mutations at the murine dominant white spotting (KitW) and steel (MgfSl) loci, encoding c-Kit receptor kinase and its ligand respectively, exert developmental defects on hematopoietic cells, melanocytes, germ cells and interstitial cells of Cajal. The expression patterns of steel factor (SLF) observed in the skin and gonads suggest that SLF mediates a migratory or a chemotactic signal for c-Kit-expressing stem cells (melanocyte precursors and primordial germ cells). By targeting expression of SLF to epidermal keratinocytes in mice, we observed extended distribution of melanocytes in a number of sites including oral epithelium and footpads where neither melanocytes nor their precursors are normally detected. In addition, enlarged pigmented spots of KitW and other spotting mutant mice were observed in the presence of the SLF transgene. These results provide direct evidence that SLF stimulates migration of melanocytes in vivo. We also present data suggesting that SLF does not simply support survival and proliferation of melanocytes but also promotes differentiation of these cells. Unexpectedly, melanocyte stem cells independent of the c-Kit signal were maintained in the skin of the SLF transgenic mice. After the elimination of c-Kit-dependent melanoblasts by function-blocking anti-c-Kit antibody, these stem cells continued to proliferate and differentiate into mature melanocytes. These melanoblasts are able to migrate to cover most of the epidermis after several months. The SLF transgenic mice described in this report will be useful in the study of melanocyte biology.

Evaluation of fluids from cystic follicles for in vitro maturation and fertilization of bovine oocytes

Follicular cysts are defined as cystic structures derived from unovulated follicles. The formation of the cysts appears to be related to failure of the oocyte to resume meiosis. The aim of this study was to evaluate in the bovine: 1) the ability of the fluid from cystic follicles to promote in vitro oocyte maturation and fertilization, 2) the predictive value of the morphology of oocytes derived from cystic follicles on the ability of the follicular fluid to promote in vitro maturation/fertilization as well as the oocytes to undergo maturation and fertilization. In Experiment 1, the ability of fluid from cystic (and normal) follicles from live and slaughtered cows (to promote) in vitro maturation and fertilization of bovine cumulus-oocyte-complexes (COC's) was assessed by cumulus expansion, sperm penetration, male pronucleus formation and polyspermy rates. Concentrations of progesterone (P4) and estradiol-17 beta (E2) were measured in the fluid from cystic follicles collected from live and slaughtered cows. In Experiment 2, we investigated the relationship of the morphology of COC's from cystic follicles, and the effect of the follicular fluids on oocyte maturation as well as P4 and E2 concentrations. In Experiment 1, although sperm penetration and male pronucleus formation were inhibited significantly by fluid from some cystic follicles collected from live and slaughtered cows, there were no significant differences in sperm penetration, male pronucleus formation and polyspermy rates between fluid from cystic follicles collected from live cows, from slaughtered cows and from control groups, regardless of the P4/E2 ratio. In Experiment 2, the morphology of cumulus-oocyte complexes from cystic follicles varied and the pronucleus formation of oocytes after in vitro fertilization was abnormal. On the other hand, the male pronucleus formation rates were not significantly different between the cystic follicular fluids and control, regardless, of the P4/E2 ratio. The results of this study suggest that many of the bovine follicular fluids from cystic follicles possess the ability to induce cumulus expansion, nuclear maturation and male pronucleus formation following in vitro maturation and fertilization of bovine oocytes. The morphology of the cumulus-oocytes complexes from cystic follicles seems not to relate to the ability of the cystic follicular fluids to induce oocyte maturation, and oocytes from cystic follicles possess the ability to form male pronucleus even though most were abnormal after in vitro fertilization.

The role of thromboxane A2 in regulating porcine basilar arterial tone

The aim of the present study was to clarify the participation of endogenous arachidonic acid (AA) metabolites in regulating porcine basilar, coronary, pulmonary and mesenteric arterial tones in vitro. A cyclooxygenase inhibitor, indomethacin, relaxed basilar artery but not other arteries examined. Quinacrine (a phospholipase A2 inhibitor), OKY-046 (a thromboxane (TX) A2 synthetase inhibitor) and ONO-3708 (a TXA2/prostaglandin H2 receptor antagonist) produced relaxation in basilar arteries with intact endothelium. Nordihydroguaiaretic acid (a lipoxygenase inhibitor) had no effect on the tone. The amount of TXB2 (a stable metabolite of TXA2) spontaneously released from porcine basilar arteries was 6-10 fold more than those from other arteries. Indomethacin and OKY-046 mostly inhibited the production of TXB2. Endothelial denudation decreased indomethacin-induced relaxation and the amount of TXB2. These results suggest that a vasoconstricting substance(s) is released from endothelial cells and possibly smooth muscle cells in porcine basilar arteries in vitro. The main constricting substance is proposed to be TXA2. On the other hand, several arteries from peripheral vascular beds did not release this vasoconstricting substance.

Effect of Helicobacter pylori infection on gastric mucosal phospholipid contents and their fatty acid composition

To investigate the effect of Helicobacter pylori infection on the 'gastric mucosal barrier', phospholipid contents and the fatty acid composition of endoscopic biopsy specimens of the gastric mucosa were analysed in healthy volunteers with and without H. pylori infection. The gastric corporeal phosphatidylcholine (PC) content of H. pylori-positive healthy volunteers was less than that of H. pylori-negative healthy volunteers (P < 0.05). Moreover, H. pylori-positive healthy volunteers had a decrease in linoleic acid composition (P < 0.0001) and an increase in arachidonic acid composition (P < 0.0001) and in the arachidonic acid/linoleic acid ratio (P < 0.0001) of antral and corporeal PC compared with H. pylori-negative healthy volunteers. These findings suggest that H. pylori infection enhances production of various eicosanoids, resulting in changes in the gastric mucosal phospholipid contents and their fatty acid composition, that may consequently cause the gastric mucosal barrier to be weakened.

Ca2+ channel modulation alters halothane-induced depression of ventricular myocytes

PURPOSE

This study examined the direct myocardial depressant effect of halothane and determined whether an L-type Ca2+ channel agonist and antagonists altered the myocardial depression induced by halothane in cultured rat ventricular myocytes.

METHODS

Ventricular myocytes were obtained from neonatal rats by enzymatic digestion with collagenase and then cultured for 6 to 7 days. The myocytes were stabilized in a serum-free medium, and the spontaneous beating rate and amplitude were measured. To assess the halothane-induced conformational changes in L-type Ca2+ channel, receptor binding study was performed using a dihydropyridine derivative, [3H] PN 200-110, in cardiac membrane preparation.

RESULTS

Halothane (1%, 2%, 3%, 4%) decreased the beating rate and amplitude in a concentration-dependent manner (P < 0.05). The myocardial depressant effects of halothane were potentiated by nifedipine or verapamil (P < 0.05). Bay K 8644, an L-type Ca2+ channel agonist, completely prevented the halothane-induced depression in amplitude (P < 0.05), but affected the beating rate less. Adding halothane (2%) decreased (P < 0.05) the maximum binding site density for [3H] PN 200-110 (from 198.6 +/- 23.7 fmol.mg-1 protein to 115.3 +/- 21.6 fmol.mg-1 protein) but did not affect binding affinity (from 0.461 +/- 0.077 nM to 0.307 +/- 0.055 nM).

CONCLUSION

The reduction of Ca2+ current via sarcolemmal L-type Ca2+ channel, probably due to conformational changes in dihydropyridine binding sites, plays an important role in halothane-induced myocardial depression in living heart cells.

Mechanism of endothelin-1 release from endothelial cells in pregnancy-induced hypertension

We investigated the mechanism of vasoconstrictor-induced endothelin-1 (ET-1) release from human umbilical vein endothelial cells (HUVECs) in serum from women with pregnancy-induced hypertension (PIH). We obtained serum samples from seven women with PIH, seven healthy nonpregnant women (NP), and seven normal pregnant women (NPIH). ET-1 and inositol 1,4,5-trisphosphate (IP3) were assayed by ET-1 ELISA and an IP3 3H assay system, respectively. ET-1 release from HUVECs incubated with 10% serum (NP, NPIH, and PIH) was greater than that without human serum. Angiotensin II (Ang II)- and epinephrine (Epi)-induced ET-1 release were significantly increased by PIH serum. IP3 production in HUVECs incubated with 10% serum (NP, NPIH, and PIH) was greater than that without human serum. Ang II- or Epi-induced IP3 production in HUVECs incubated with PIH serum was increased but not significantly compared to that with other sera. Our results suggest that increased ET-1 release from HUVECs incubated with human serum may be mediated by IP3 production, but that Ang II- or Epi-induced ET-1 release from HUVECs incubated with PIH serum may be mediated by another mechanism.

Molecular diversity and double regulatory mechanism of activation of phospholipase C in rat brain

Whereas evidence for a G protein-dependent stimulation of phospholipase C (PLC) is abundant, reports on the inhibition of PLC through a G protein-mediated pathway have only recently begun to appear. In the present study, cerebral cortex membranes were chosen since they have a readily measurable Gpp[NH]p and Ca2+-stimulated PLC activity. Nanomolar concentrations of Gpp[NH]p, a hydrolysis-resistant GTP analogue, inhibited basal inositol 1,4,5-trisphosphate (IP3) production, with a maximum inhibition of 25% at 10 nM. Increasing the concentrations of Gpp[NH]p to over 10 nM resulted in a reversal of the inhibitory effect and onset of stimulation of IP3 production. GDPbetaS as a G protein inhibitor and U-73122 as a putative PLC-beta inhibitor had little effect on basal IP3 production at 100 microM and 1 microM, respectively. However, GDPbetaS and U-73122 completely antagonized both the inhibition and the stimulation of IP3 production produced by lower and higher concentrations, respectively, of Gpp[NH]p. Rat cortical membranes expressed a greater amount of PLC-beta1. These data suggest that PLC-beta1 isozymes may be regulated by both inhibitory and stimulatory G protein-mediated mechanisms.

Oocyte quality of small antral follicles coexisting with cystic follicles in the ovaries of the cow

The present study was conducted with ovaries to evaluate the effect of the presence of a cystic follicle and its steroid hormone concentration on the oocyte recovery rates, oocyte morphology and in vitro maturation of the oocytes from coexisting small follicles. Ovaries, each bearing a follicular cyst (containing > 10 ml of follicular fluids, > 3 cm in diameter, and without a functional corpus luteum), were collected from each of the 26 Holstein cows from a local slaughterhouse. Small follicles (1-7 mm) from these ovaries were aspirated and their cumulus-oocyte complexes (COCs) classified into one of 5 groups (A to E), depending on oocyte and cumulus cell morphologies. Those oocytes with compact cumulus cells were cultured and their maturation rates determined. Concentrations of estradiol-17 beta (E2) and progesterone (P4) were measured in cystic follicular fluid using double antibody enzyme immunoassays (EIA). The morphology of the COCs and maturation rates of the oocytes were then evaluated using two comparisons. In first comparison, the left and right ovaries obtained from an individual cow were considered as a pair, with each pair being divided into two groups depending on the presence or absence of an E2 dominant or P4 dominant cystic follicle in one or another of the ovaries: E2 dominant cows; and P4 dominant cows. Oocytes collected from the ovaries of cyclic cows at follicular, luteal and post-ovulatory stages served as controls. The oocyte recovery rates, oocyte morphologies and oocyte maturation rates were independent of the presence or absence of a coexisting cystic follicle, or its steroid hormone classification or concentration. In the second comparison, each ovary was consider individually and divided into one of the two classes, depending on the presence or absence of a cystic follicle. Those ovaries with cystic follicles were then divided into three subclasses on the basis of E2 and P4 concentrations in the cystic follicular fluids: P4 dominant (P4/E2 ratio > 1); E2 dominant (P4/E2 ratio < 1); and both P4 and E2 dominant follicles present. The numbers of oocytes obtained from an ovary, their morphology and their maturation rates were not significantly different in the presence or absence of a coexisting cystic follicle. Moreover, the number of the oocytes aspirated from an ovary, their morphology and their maturation rates in small follicles coexisting with P4 dominant, E2 dominant and both P4 and E2 dominant cystic follicles were also not different. These results suggested that neither the presence of a cystic follicle in a cow's ovary nor the cyst's steroid hormone concentrations affected the oocyte recovery rate, oocyte morphology and maturation rates of the coexisting small follicles.

Medical baseline data collection on bone and muscle change with space flight

It has been documented that astronauts suffer from a progressive and continuous negative calcium balance in space flight. The National Space Development Agency of Japan (NASDA) discussed the experimental protocols with the National Aeronautics and Space Agency's (NASA's) Johnson Space Center (JSC) and has started a medical baseline collection on bone and calcium metabolism, and muscle changes with space flight. The subjects were two astronauts, a 42-year-old female and a 32-year-old male, who experienced real space flights. Fractional excretion of calcium (FECa) increased in both subjects just after the space flight. There was a negative calcium balance with urinary calcium leak even after a short flight. We also noticed a decrease (-3.0%) of bone mineral density (BMD) of the lumbar spine (L2-4), a weight bearing bone. These bone changes may be due to a negative calcium balance. However, the BMD of the skull, a nonweight bearing bone, increased after the flight. This indicates that the effect of weightlessness on bone is different in respective bones, depending on the weight loading. Our data of the bone metabolic marker clearly indicate that bone resorption is stimulated, shown by an elevation of urinary pyridinolinks and plasma tartrate-resistant acid phosphate (TRACP) activity. Bone specific alkaline phosphatase, a bone formation marker, was elevated in both subjects, but not intact osteocalcin. Whether this pathophysiological phenomenon is due to an accelerated bone resorption or suppressed bone formation is still obscure. In addition, the physiological cross-sectional area (PCSA) of muscle in the legs greatly decreased (from - 10% to -15%) after the flight, and it took over a month to be recovered in both subjects. However, the muscle volume loss in the legs seemed to be reversible. To examine bone and muscle metabolism with space flight, further investigations and international standardization of experimental protocols are necessary.

A competitive enzyme immunoassay for follicle-stimulating hormone in ovine plasma using biotin-streptavidin amplification

To determine follicle-stimulating hormone (FSH) concentration in ovine plasma, a second-antibody enzyme immunoassay using biotin-streptavidin amplification (BS-EIA) was developed and was validated by comparison with a routine radioimmunoassay (RIA). Ovine FSH was labelled with D-biotinyl-epsilon-aminocaproic acid-N-hydroxysuccinimide ester (biotin-7-NHS). The minimum and maximum detection limits were 0.40 ng mL(-1) and 25.0 ng mL(-1) respectively in the BS-EIA. Plasma samples from three superovulated ewes were measured for FSH by both BS-EIA and RIA. Correlation between values obtained by BS-EIA and RIA was 0.86 (n = 106), and the linear regression had a slope of 0.88 and an intercept of -0.07 (R2 = 0.74). The baseline of BS-EIA was slightly lower than that of RIA (0.69 ng mL(-1) v. 1.10 ng mL(-1)). The intra-assay and inter-assay coefficients of variation in BS-EIA were 13.8% and 16.7% (n = 106) respectively. The recovery rates were 104.8+/-2.7% (mean+/-s.e.m., n = 14). Changes in plasma FSH concentration from superovulated ewes evaluated by BS-EIA corresponded well with the results of routine RIA.

Association of SET domain and myotubularin-related proteins modulates growth control

Several proteins that contribute to epigenetic mechanisms of gene regulation contain a characteristic motif of unknown function called the SET (Suvar3-9, Enhancer-of-zeste, Trithorax) domain. We have demonstrated that SET domains mediate highly conserved interactions with a specific family of proteins that display similarity with dual-specificity phosphatases (dsPTPases). These include myotubularin, the gene of which is mutated in a subset of patients with X-linked myotubular myopathy, and Sbf1, a newly isolated homologue of myotubularin. In contrast with myotubularin, Sbf1 lacks a functional catalytic domain which dephosphorylates phospho-tyrosine and serine-containing peptides in vitro. Competitive interference of endogenous SET domain-dsPTPase interactions by forced expression of Sbf1 induced oncogenic transformation of NIH 3T3 fibroblasts and impaired the in vitro differentiation of C2 myoblast cells. We conclude that myotubularin-type phosphatases link SET-domain containing components of the epigenetic regulatory machinery with signalling pathways involved in growth and differentiation.

Postinfarction ventricular septal defect

Despite improved screening and diagnostic capabilities for the presence of coronary artery disease (CAD), with the promise of improved outcomes from earlier therapeutic interventions, postinfarction ventricular septal perforation (VSD) continues to be a very difficult therapeutic challenge. In our experience with VSD, the incidence of this complication per year has decreased, almost certainly related to earlier and more effective medical therapy in patients with CAD. By contrast, the outcomes of surgical repair have not improved, even with an aggressive strategy about bypassing involved coronary arteries. Furthermore, the earliest possible surgical approach and the incorporation of a number of technical advances, especially those relating to myocardial preservation, have not had an apparent effect. Because the number of patients who underwent operation is small, it is not possible from our single-institutional experience to define statistical significance to our continuing observations of this condition, suggesting that the clinical spectrum of postinfarction VSD is still evolving. Important changes appear to be associated with an increase in the number of female patients observed (60%), in contrast to their lesser frequency of uncomplicated coronary bypass (18%) and a change in the anatomic substrate, with posterior infarctions and rupture now accounting for 73% of cases at Cedars-Sinai. For the present, earliest possible surgical intervention to minimize the severity of multi-organ failure and use all of the advanced therapeutic modalities of cardiac support and surgical therapy that are available continues to be indicated. For the long term, continuing advances in the earlier diagnosis and more aggressive management of CAD, especially in females, may hold the best promise for a continued decrease in the occurrence of this very difficult-to-treat postinfarction complication.

Cyclic vomiting and elevation of creatine kinase associated with bitemporal hypoperfusion and EEG abnormalities: a migraine equivalent?

A 13-year-old mentally retarded boy suffered from repeated vomiting attacks since infancy. Each episode lasted 2 to 10 days, and was precipitated by respiratory infection, exercise or stress. During an attack he became irritated, agitated and amnesic, but did not have headaches or seizures. Associated findings were transient elevation of serum creatine kinase (CK) (331-3381 IU/l), and of plasma ACTH and cortisol. The raised CK level was the result of muscle hypertonicity. Ictal EEGs showed delta activity in the front-temporal areas, and inter-ictal IMP-SPECT revealed hypoperfusion in both temporal regions. Unlike the periodic ACTH-ADH discharge syndrome, neither hypertension nor depression developed. These attacks were diagnosed as a migraine equivalent and were suppressed with phenytoin. From the EEG and SPECT findings, we concluded that the vomiting and behavioural changes were related to the paroxysmal vascular abnormality in the temporal regions, but it was not easy to make the distinction between migraine and focal epilepsy. Before a diagnosis of the periodic ACTH-ADH discharge syndrome is made, the possibility of migraine equivalent should be considered.

Negative chronotropic effect of botulinum toxin on neonatal rat cardiac myocytes

We demonstrated that botulinum neurotoxin attenuated the spontaneous beating rate of cultured cardiac myocytes. Primary cultured cardiac myocytes were prepared from the ventricles of neonatal Wistar rats (1-3 days old). On 7 days after cell seeding, botulinum toxin type A incorporated into liposomes was added to the culture medium. At a final concentration of 5.0 micrograms/ml, botulinum toxin markedly attenuated the beating rate of cardiac myocytes within 2-4 hours. These results demonstrated the effect of SNARE-complex proteins on the spontaneous beating of cardiac myocytes.