Ultrastructure of the developing stomach in human embryos

Ultrastructural development of the stomach was studied by light, scanning electron and transmission electron microscopy, using 19 human embryos at Carnegie stages from 14 to 23 (6.8-28.0 mm in crown-rump length, 5 to 8 weeks of gestation). The precise time of appearance of differentiated characteristic structures was examined electron microscopically. The first gastric pit, with radially arranged epithelial cells beneath which the basement membrane bulged into the mesenchyme, was observed on the lesser curvature at stage 22. Although the mesenchymal condensation which would develop into the inner circular muscle layer appeared at stage 18 onward, cytoplasmic myofibrils were not observed until stage 22. Nerve fibers were first observed at stage 16, and at later stages they gathered into bundles to form a nerve plexus external to the developing inner circular muscle layer. On the basis of accurate timing of the appearance and the mode of development of these structures, possible relations between developing gastric layers were discussed. Histocytochemically, glycogen or other carbohydrates were demonstrated in the cytoplasm of the gastric epithelium throughout the stages examined. These carbohydrates were localized mainly in vacuole-like spaces in the basal part of the epithelial cells. This subcellular localization, and the amount of carbohydrate, did not change significantly during the observed embryonic period. In the serosa, carbohydrates were not detected at stages 14 and 15, but observed consistently within the vacuoles in the cytoplasm from stage 17 onward. No other layer of the embryonic stomach had detectable carbohydrates.(ABSTRACT TRUNCATED AT 250 WORDS)

99mTc-HMDP accumulation in a phyllodes tumor of the breast, a case report

In a patient with breast tumor, 99mTc-HMDP accumulation in the tumor was recognized in evaluating bone metastasis. Surgery and histopathology revealed that the tumor was a phyllodes tumor. This scintigraphic finding was thought to be rare and phyllodes tumor should be included in differential diagnosis when 99mTc-HMDP accumulation in the breast was recognized.

Differential induction of regulatory genes during mesoderm formation in Xenopus laevis embryos

Mesoderm development in Xenopus laevis depends on inductive cell interactions mediated by diffusible molecules. The mesoderm inducer activin is capable of redirecting the development of animal explants both morphologically and biochemically. We have studied the induction of four regulatory genes, Mix. 1, goosecoid (gsc), Xlim-1, and Xbra in such explants by activin, and the influence of other factors on this induction. Activin induction of gsc is strongly enhanced by dorsalization of the embryo by LiCl, while expression of the other genes is only slightly enhanced. The protein synthesis inhibitor cycloheximide (CHX) inhibits the activin-dependent induction of Xbra partially, while induction of Mix. 1 and Xlim-1 is essentially unaffected. In contrast, gsc shows strong superinduction in the presence of activin and CHX, and can be induced in animal explants by CHX alone. Induction and superinduction by CHX have previously been observed for immediate early genes in a variety of systems, notably for the activation of c-fos expression by serum stimulation, but have not been reported in early amphibian embryos.

Different patterns of protein kinase C redistribution mediated by alpha 1-adrenoceptor stimulation and phorbol ester in rat isolated left ventricular papillary muscle

1. In rat left ventricular papillary muscle, phenylephrine, an alpha 1-adrenoceptor agonist, had a staurosporine-sensitive positive inotropic effect and increased the particulate-associated protein kinase C (PKC) activity without significant changes in total PKC activity or in cytosolic Ca2+/phospholipid-independent kinase (PKI) activity. 2. A PKC stimulant, phorbol 12,13-dibutyrate (PDBu), decreased contractility and slightly increased PKC activity in the particulate fractions, with a marked decrease and increase in total PKC and PKI activities, respectively. 3. The PDBu-induced negative inotropic response was attenuated by two protease inhibitors, leupeptine and a microbial peptide isolated from Aspergillus japonicus (E-64), which are known to inhibit the conversion of particulate-associated PKC to PKI. 4. Such differences in the patterns of PKC redistribution, i.e. marked increases in particulate PKC and cytosolic PKI activities caused by phenylephrine and PDBu, respectively, may account for the opposite inotropic effects of PKC stimulation by an alpha 1-agonist and a phorbol ester.

Supra-neuroectodermal cells and fibers on the primary nasal cavity and in the fourth ventricle of mouse and human embryos: scanning and transmission electron microscopic studies

Neuroectoderm-derived epithelia of the primary nasal cavity and the fourth ventricular floor and roof were observed by scanning (SEM) and transmission electron microscopy (TEM) and SEM-TEM correlative views in mouse embryos of 9th to 13th days of gestation, and in 38 externally normal human embryos ranging at Carnegie stages from 13 to 18 (about 5 to 7 weeks of gestation). Smooth-surfaced spindle-shaped cells with one or more cytoplasmic processes and cord-like cytoplasmic structures were observed by SEM on the wall of the primary nasal cavity of both species. They had morphological features similar to those of neuronal type 1 supraependymal (SE) cells and SE fibers on the floor and roof of the fourth ventricle in both species. Type 1 SE cells, SE fibers, and corresponding structures in the primary nasal cavity were localized in relation to the underlying developing nerve and vascular systems. Furthermore, their processes and fibers ran roughly parallel to these underlying structures and they penetrated the epithelial layer at the ends, suggesting a connection with underlying structures. From TEM and SEM-TEM correlative observations, SE fibers in the fourth ventricle and cord-like structures in the primary nasal cavity, both with a larger diameter, were deduced as single axon-like processes or bundles of processes. Those fibers and cord-like structures of smaller diameters were interpreted as elongated telophase bridges; both contained parallel packed microtubules and connected distant cells. Since these processes and fibers were generally longer and became fewer at later developmental stages, they appeared to be transient neuronal structures. They may play a development-related role in such morphogenetic cell movements as in the developing nerve and vascular systems in the epithelial and/or subepithelial layers, but not as direct rudiments of adult nerve tissues.

Age differences in perception of risk

Age differences in perception of risk and the likelihood of disregarding warning signs were examined. A total of 358 adults, between 18 and 85 years old, were asked to rate 12 warning labels with respect to (a) how risky it would be to ignore the warning, (b) how likely it was that they would disregard the warning, and (c) how familiar they were with the labels. The older groups indicated higher risk in ignoring the signs than did the younger group. The older subjects were also less willing to disregard the signs than the younger subjects.

Interleukin (IL)-2 and IL-3 induce distinct but overlapping responses in murine IL-3-dependent 32D cells transduced with human IL-2 receptor beta chain: involvement of tyrosine kinase(s) other than p56lck

We have established IL-3-dependent 32D myeloid progenitor cells stably expressing the human IL-2 receptor beta chain (IL-2R beta). Whereas parental 32D cells proliferated only in response to IL-3, the transduced cells also proliferated in response to IL-2. Transduced cells expressed high- and intermediate-affinity IL-2Rs, resulting from expression of human IL-2R beta and murine IL-2R alpha chain (IL-2R alpha). IL-2 induced phenotypic changes not induced by IL-3, including the upregulated expression of endogenous murine IL-2R alpha and IL-2R beta and an increase in cell size. Therefore, the transduced IL-2R beta was not merely coupling with the IL-3 signaling pathway. IL-3 augmented several IL-2-induced responses including the up-regulation of IL-2R alpha. Both IL-2- and IL-3-induced proliferation and IL-2 induced IL-2R alpha expression were inhibited by the tyrosine kinase inhibitor herbimycin A. Thus, both IL-2- and IL-3-mediated effects required tyrosine kinase activity. The identity of the tyrosine kinase(s) mediating the IL-2 signals in these cells is not known but cannot be p56lck, a tyrosine kinase found in T cells, since 32D-IL-2R beta cells do not express p56lck.

Interleukin (IL)-2 activation of p21ras in murine myeloid cells transfected with human IL-2 receptor beta chain

The T cell growth factor interleukin-2 (IL-2) induces p21ras activation in T lymphocytes. To determine whether the IL-2 receptor (IL-2R) can regulate p21ras when expressed in a non-T cell environment we have examined the ability of IL-2 to activate p21ras in 32D murine myeloid progenitor cells transduced with human IL-2R beta chains. These cells are denoted beta 53 cells. 32D cells normally proliferate in response to IL-3 but the expression of the IL-2R beta chain confers IL-2 responsiveness to the cells. Our data show that IL-3 is able to activate p21ras in the parental 32D cells and both IL-2 and IL-3 can stimulate p21ras in the IL-2R-expressing beta 53 clone of 32D. In T lymphocytes, activation of protein kinase C (PKC) with phorbol esters is sufficient to stimulate p21ras. However, in 32D and beta 53 cells activation of PKC with phorbol esters does not result in p21ras activation even though these cells express functional PKC. It appears, therefore, that a PKC-mediated pathway for p21ras regulation exists in T lymphocytes but not in 32D cells. The IL-2R can couple to p21ras independently of the concomitant presence of the PKC pathway for p21ras regulation. These data imply that multiple intracellular mechanisms may exist to regulate p21ras and that cells of different lineages may differ with regard to p21ras regulation.

[Relationship between venous invasion and hematogenous metastasis in the colorectal cancer patients]

We investigated the correlation between venous invasion and hematogenous metastasis. In thirteen patients with colorectal carcinoma, depth of invasion (ss.s or a1.a2) was the same. Four cases had hepatic metastasis at operation (group A), 3 cases were identified with hematogenous recurrence after operation (group B), and 6 cases were disease free over 10 years after operation (group C). Specimens were all step-sectioned and serial sections were stained both with HE and EM. Results were as follows. 1. Venous invasion was found in all cases and average rates of venous invasion (ARVI) of groups A and B were higher than that of group C (A; 7.8%, B; 6.3%, C; 2.1%, p less than 0.05). 2. In ss.s layer, ARVI of group A and B were higher than that of group C (A; 6.1%, B; 6.2%, C; 1.5%, p less than 0.05). 3. Rates of venous invasion to larger veins (diameter greater than 200 microns) were higher in group A than in others (A; 53.5%, B; 25.6%, C; 7.9%, p less than 0.05), and those to the middle-sized veins (diameter; 50-200 microns) were higher in group B than in others. These facts suggest that cancer invasion to the veins located in ss.s (a1.a2) layer or ranged in diameter over 200 microns relates to hematogenous metastasis.

Effect of cardioplegic preservation on intracellular calcium transients

Intracellular Ca2+ ([Ca2+]i) plays a pivotal role in the regulation of cardiac function. We investigated the effect of cardioplegic preservation on [Ca2+]i transients in the isolated and perfused guinea pig heart loaded with a fluorescent Ca2+ indicator (fura-2). The measurements of [Ca2+]i transients and isovolumetric left ventricular pressure revealed that [Ca2+]i transients and mechanical responses to [Ca2+]i were markedly altered during 15 minutes of normothermic global ischemia and after reperfusion. First, [Ca2+]i transients remained during ischemia without generation of active force of contraction. Such a manifestation of depressed sensitivity of the myofilaments to Ca2+ persisted for the first 5 minutes after reperfusion. Second, the amplitude of [Ca2+]i was diminished during ischemia and reperfusion. Third, diastolic [Ca2+]i was increased during ischemia and especially at the onset of reperfusion. Bolus infusion of cold St. Thomas' Hospital solution abolished [Ca2+]i transients and left ventricular pressure development at an end-diastolic level. Moreover, improved recovery of left ventricular function during reperfusion afforded by the hypothermic cardioplegia was intimately related to its ability to modulate impaired [Ca2+]i transients and mechanical responses to [Ca2+]i; improvement of systolic left ventricular function appears to be produced by restoration of Ca2+ sensitivity of the myofilaments and the amplitude of [Ca2+]i transients, whereas better diastolic compliance of the left ventricle is ascribed to significantly lower diastolic [Ca2+]i. These results may provide new insight into the mechanism of cardioplegic preservation on the basis of [Ca2+]i transients.

Diabetic environment and genetic predisposition as causes of congenital malformations in NOD mouse embryos

Congenital malformations such as neural tube defects and a kinky or waved vertebral column were observed at higher incidence in embryos from nonobese diabetic (NOD) female mice with overt diabetes (NOD-D; 40.3%, P less than 0.005) or without overt diabetes (NOD-N; 8.4%, P less than 0.05) than in control Institute of Cancer Research (ICR) mouse embryos (1%) at day 13 of gestation. In vivo and in vitro preimplantation development of NOD-N, NOD-D, and ICR embryos did not differ in rate of development, size, or morphology. Embryos cultured from one-cell to early blastocyst stage were mutually transferred to uterine horns of pseudopregnant females between NOD-D and ICR mice and examined at day 13 of gestation. There were significant decreases in ratios of implantation and of viable embryos in ICR embryos transferred to NOD-D recipients (52%, P less than 0.001 and 14%, P less than 0.001, respectively) compared with those ratios in ICR embryos transferred to ICR uteri (79.2 and 56.2%) or those in NOD-D embryos transferred to ICR uteri (70.3 and 33.1%). Furthermore, 18 of 45 viable ICR embryos transferred to NOD-D dams had malformations, whereas there were no malformations in 73 viable ICR embryos transferred to ICR recipients, suggesting deleterious effects of maternal diabetic environment to embryos. On the other hand, 8 of 58 viable NOD-D embryos that were cultured in vitro and transferred to ICR uteri had malformations such as neural tube defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of amiloride and an analogue on ventricular arrhythmias, contracture and cellular injury during reperfusion in isolated and perfused guinea pig heart

The present study was designed to examine whether activation of Na+/H+ exchange and subsequent massive Ca2+ influx via Na+/Ca2+ exchange are involved in the pathogenesis of myocardial reperfusion injury. We tested the effects of 1 mM amiloride, which is known to inhibit both Na+/H+ and Na+/Ca2+ exchange, and 3 microM 5-(N-ethyl-N-isopropyl) amiloride (EIPA), which is known to act as a specific inhibitor against Na+/H+ exchange, on the incidence of ventricular arrhythmias, isovolumic left ventricular function and creatine kinase (CK) release during reperfusion after 15 or 30 min of global ischemia in the isolated and perfused guinea pig heart. Treatment of a normally perfused heart with amiloride decreased heart rate significantly and tended to increase coronary flow and left ventricular developed pressure (LVDP), whereas treatment with EIPA decreased all of these 3 measurements significantly. Treatment with amiloride or EIPA for 15 min before ischemia, and during reperfusion after 15 min of ischemia, under electrical pacing at 240 rpm to eliminate a negative chronotropic effect abolished ventricular tachycardia (VT) and ventricular fibrillation (VF) during reperfusion associated with highly significant inhibition of increases in left ventricular end-diastolic pressure (LVEDP) and CK release. Amiloride or EIPA pretreatment also inhibited the incidence of VF and increases in LVEDP and CK release significantly during reperfusion after 30 min of ischemia. However, amiloride was more effective in preventing these events than EIPA. The treatment with amiloride or EIPA only during reperfusion after 15 or 30 min of ischemia also decreased the incidence of VF and inhibited the increases in LVEDP and CK release significantly, though less effectively than the pretreatment modality. These results suggest that EIPA prevents ventricular arrhythmias, contracture and myocardial cellular injury during reperfusion after 15 min of ischemia by inhibiting Na+/H+ exchange, while amiloride exerts more powerful protection against these events than EIPA during reperfusion after 30 min of ischemia by inhibiting both Na+/H+ and Na+/Ca2+ exchange.

Host recognition by toxigenic plant pathogens

Certain fungal pathogens release host-selective (or host-specific) toxins (HST) as a host recognition factor during spore germination at the infection site on plants. Prior to penetration of the pathogen into its host, the released toxin specifically binds to a putative receptor on the host cells and initiates signaling mechanisms leading to pleiotropic effects on cells. Of these, the crucial one negates the general and inducible defense reactions of the cells. This is accomplished by a signal from the HST, which is transduced through a path way at or near the step of plasma membrane modulation, which is directly or indirectly triggered by the HST. This mechanism operates even though the toxin may affect mitochondria or chloroplasts as the primary target organelle. The fungal spore is able to penetrate the so-called 'narcotized cell' and completes the initial colonization of the host. The host recognition process may take place without necessitating host cell death, even in the case of perthophytic parasites. At the molecular level, HST-mediated recognition of the host by a pathogen requires strict stereochemical precision like a lock and key.

Histochemically demonstrable phosphotyrosine protein phosphatase in the rat hippocampal formation

Using o-phospho-L-tyrosine as substrate, a possible localization of phosphotyrosine protein phosphatase (PTPPase) activity was histochemically demonstrated in the rat hippocampal formation. The PTPPase activity was found in almost all layers of the hippocampal formation, with a high activity in the stratum moleculare. The activity was inhibited by vanadate and molybdate, but not by NaF and Zn2+. The activity was localized in the dendritic cytoplasm, particularly on the postsynaptic density, of hippocampal neurons.

Surface condition of primary teeth after approximal grinding and polishing

Mesiodistal reduction of primary teeth is necessary in cases with mild or moderate primary crowding, in patients treated with Fränkel appliance type I or II or in those who need to keep a primary molar as long as possible due to congenitally missing premolars. In order to minimize the risks of periodontal destruction and caries, the tooth surface should be polished after grinding. A technique for stripping permanent teeth, recently proven successful in achieving smoother enamel than untreated tooth surfaces, was slightly varied and applied to primary teeth. By means of scanning electron micrographs, it could be shown that application of this technique produces smooth surfaces on primary teeth as well. The procedure is described in detail and cases in which it should be used are presented.

Chromosome analysis of postimplantation stage embryos for studying possible causes of developmental abnormalities in nonobese diabetic mice

The chromosomes of postimplantation stage embryos of nonobese diabetic (NOD) mice were analyzed to investigate the causal mechanism of congenital anomalies in diabetic pregnancies. Postimplantation stage embryos (day 12 of gestation) in diabetic (NOD-DM) and nondiabetic (NOD-N) NOD mice had either a high or low incidence of chromosomal abnormalities. A large majority of externally normal embryos from NOD-DM and NOD-N mice had low incidences. A high incidence of chromosomal abnormalities was found in externally abnormal embryos of NOD-DM and NOD-N mice, and in a smaller number of externally normal NOD-N and NOD-DM embryos. No control ICR embryo manifested a high incidence of chromosomal abnormalities. In the NOD-DM embryos, the chromosomes appeared to be influenced by long-term maternal diabetic conditions, while high incidences of chromosomal abnormalities in the NOD-N embryos suggested a probable cause by other factor(s) (e.g. a genetic predisposition) or by a very mild diabetic condition because the NOD-N mice were prediabetic.

Effects of inhibitors of protein kinase C and Na+/H+ exchange on alpha 1-adrenoceptor-mediated inotropic responses in the rat left ventricular papillary muscle

1. Alpha 1-adrenoceptor stimulation of rat left ventricular papillary muscle produced a triphasic inotropic response: an initial transient positive inotropic effect (PIE) followed by a transient negative inotropic effect (NIE) and a sustained PIE. 2. The protein kinase C inhibitor, staurosporine, at concentrations ranging from 30 nM to 100 nM inhibited the sustained PIE, but had no significant effect on the transient PIE and NIE. 3. H-7, 1-(5-isoquinoline sulphonyl)-2-methylpiperazine, a less specific inhibitor of protein kinase C than staurosporine, at a concentration of 100 microM inhibited both the transient NIE and the sustained PIE without affecting the transient PIE. 4. Amiloride, an inhibitor of Na+/H+ exchange, at concentrations ranging from 0.1 mM to 1 mM inhibited the sustained PIE and, at higher concentrations, also inhibited the transient NIE. 5. An amiloride analogue, 5-(N-methyl-N-isobutyl)amiloride (MIBA), inhibited only the sustained PIE with an IC50 of 0.3 microM which is approximately two orders of magnitude lower than amiloride. 6. The receptor-linked stimulation of Na+/H+ exchange through protein kinase C activation may be a mechanism for alpha 1-adrenoceptor-mediated sustained PIE.

Human interleukin 2 receptor beta-chain gene: chromosomal localization and identification of 5' regulatory sequences

Interleukin 2 (IL-2) binds to and stimulates activated T cells through high-affinity IL-2 receptors (IL-2Rs). Such receptors represent a complex consisting of at least two proteins, the 55-kDa IL-2R alpha chain and the 70-kDa IL-2R beta chain. The low-affinity, IL-2R alpha chain cannot by itself transduce a mitogenic signal, whereas IL-2 stimulates resting lymphocytes through the intermediate-affinity, IL-2R beta receptor. We report here identification of the genomic locus for IL-2R beta. The exons are contained on four EcoRI fragments of 1.1, 9.2, 7.2, and 13.7 kilobases. The 1.1-kilobase EcoRI fragment lies at the 5'-most end of the genomic locus and contains promoter sequences. The promoter contains no TATA box-like elements but does contain the d(GT)n class of middle repetitive elements, which may play an interesting regulatory role. The IL-2R beta gene is localized to chromosome 22q11.2-q12, a region that is the locus for several lymphoid neoplasias.

Role of a nonsteroidal anti-inflammatory agent, ibuprofen, in coronary revascularization after acute myocardial infarction

The efficacy of using a nonsteroidal anti-inflammatory agent such as ibuprofen for the salvage of ischemic and reperfused myocardium was investigated by examining its ability to improve global and regional functions as well as to preserve high-energy phosphate compounds and inhibit creatine kinase release from an isolated in-situ pig heart subjected to 1 h of normothermic regional ischemia followed by 1 h of global hypothermic arrest and 1 h of normothermic reperfusion. Preperfusion of the heart for 15 min prior to ischemic insult with 50 microM ibuprofen failed to mitigate the myocardial reperfusion injury. Ibuprofen, however, functioned as an anti-inflammatory agent, as judged by its ability to inhibit the influx of indium-111-labeled polymorphonuclear leukocytes and chromium-51 (51Cr)-labeled platelets into the ischemic and reperfused heart. It also blocked the cyclooxygenase pathway, as evidenced by the significant reduction of 6-keto-prostaglandin F1 alpha and thromboxane B2 concentrations in the perfusate. Inhibition of cyclooxygenase resulted in increased accumulation of nonesterified fatty acids, particularly arachidonic acid, in the heart. These results suggest that although ibuprofen can inhibit polymorphonuclear leukocyte and platelet influx into the ischemic and reperfused heart, it causes further damage to the already ischemic heart by reducing prostacyclin concentration and increasing free fatty acids in the heart.

[The experimental study on long-term cardiac preservation: the efficacy of low-flow continuous perfusion with fluorocarbon]

We compared the effect of simple immersion and continuous perfusion on long-term cardiac preservation, and evaluated the effectiveness of perfusion with oxygenated fluorocarbon solution. The isolated rabbit hearts were preserved for 24 hours at 4 degrees C using the following five preservation techniques: (1) simple immersion with Collins M solution (Group I), (2) perfusion with oxygenated Collins M solution at a flow rate of 10 ml/hr (Group II), (3) perfusion with the same solution as in Group II at a flow rate of 20 ml/hr (Group III), (4) perfusion with oxygenated Collins M solution containing 10% fluorocarbon at a flow rate of 10 ml/hr (Group IV), (5) perfusion with the same solution as in Group IV at a flow rate of 20 ml/hr (Group V). The hearts of Group I showed a significant decrease of myocardial ATP and an increase of myocardial lactate during preservation compared to the hearts of perfusion groups. Assessment of isovolumic left ventricular function following 24-hour preservation using a support animal showed a significant decrease of Max dp/dt and increase of end-diastolic pressure in the hearts of Group I. Perfusion with fluorocarbon (Group IV and V) significantly increased oxygen consumption compared to Group II and III in association with minimum accumulation of myocardial lactate, indicating that aerobic metabolism during preservation is better maintained in the fluorocarbon-perfused hearts. Moreover, CPK release and myocardial water gain during preservation were significantly less, and left ventricular function following preservation was significantly better in these hearts. Increasing the flow rate from 10 ml/hr to 20 ml/hr resulted in sustained increase in perfusion pressure (1.80 +/- 0.53 to 3.70 +/- 0.34 mmHg) and myocardial water content (79.2 +/- 0.4 to 87.2 +/- 0.3%) during preservation in the hearts of Group III, but it did not further improve left ventricular function despite significant enhancement of myocardial oxygen uptake in both Group III and V. These results suggest that hypothermic low-flow continuous perfusion with oxygenated Collins M solution is superior to simple immersion with the same solution for long-term cardiac preservation, and that the addition of fluorocarbon to the perfusate enhances the efficacy of such a perfusion.

Effect of calcium overload on the phosphoinositide breakdown in the rat left ventricular papillary muscle

We investigated the effect of Ca2+ overload on the phospholipase C-catalyzed hydrolysis of phosphoinositides in the rat left ventricular papillary muscle. Ca2+ overload on the papillary muscle was induced by treatment with 0.3 mM ouabain in Ca2+-containing medium following either Ca2+-containing or Ca2+-free superfusion. The phosphoinositide breakdown was evaluated by determining accumulations of [3H]inositol phosphates ([3H]IPs) in the tissues prelabeled with [3H]inositol. Ca2+ repletion following Ca2+-free superfusion resulted in a rapid but small increase in resting tension that was not followed by contracture, nor was it associated with a significant increase in [3H]IPs accumulations. Treatment with ouabain following Ca2+-containing superfusion increased resting tension after a lag period of several minutes and produced contracture associated with an increase in [3H]IPs accumulations. The ouabain induced increases in resting tension, and accumulations of [3H]IPs were significantly potentiated by prior Ca2+-free superfusion instead of Ca2+-containing superfusion. There was a significant positive correlation between increases in resting tension and the phosphoinositide breakdown. The increased resting tension and the accumulations of [3H]IPs were not antagonized by treatments with prazosin plus atropine or indomethacin, but were abolished by superfusion with Ca2+-free buffer solution. Although the enhanced phospholipase C-catalyzed hydrolysis of phosphoinositides appears to be a consequence rather than a cause of increased intracellular Ca2+, such a biochemical change may provoke a positive feedback mechanism to develop the muscle contracture through the putative intracellular messenger action of inositol triphosphate and diacylglycerol.

Intracerebroventricular injection of ethacrynic acid induces status epilepticus

The intracerebroventricular (i.c.v.) injection of ethacrynic acid to mice at a dose of more than 25 micrograms induced repeated tonic-clonic convulsions with subsequent death. Ethacrynic acid was more potent than other loop diuretics such as furosemide and bumetanide. Diazepam and 2-amino-5-phosphonovaleric acid notably reduced both the incidence of convulsion and the lethality seen after ethacrynic acid administration. Both phenobarbital and ketamine suppressed the incidence of convulsions but not the lethality. Without effects on the incidence of convulsions or lethality, dextromethorphan prolonged, while phenytoin or atropine shortened, the time to the onset of convulsion. Neither ethosuximide, carbamazepine, nor muscimol had a significant effect on the responses to ethacrynic acid. The present findings indicate that i.c.v. injected ethacrynic acid shows strong convulsive activity, probably due to impairment of Cl- transport processes, concomitant with enhancement of excitatory amino acid activity in the brain.

Mechanism of membrane phospholipid degradation in ischemic-reperfused rat hearts

We investigated the mechanism of membrane phospholipid degradation during reperfusion of ischemic myocardium using isolated and perfused rat hearts. Thirty min of myocardial reperfusion after 30 min of normothermic global ischemia resulted in a significant decrease of phosphatidylcholine (PC) content associated with a small but significant increase in lysophosphatidylcholine (LPC) content. Myocardial ischemia for up to 60 min caused no significant loss of any of the major phospholipids. Isotopic incorporation of [14C]arachidonic acid (AA) as well as [3H]-glycerol into PC was significantly attenuated in the ischemic-reperfused heart compared with the normally perfused heart, suggesting that both reacylation and de novo pathways for PC synthesis were inactivated during reperfusion. In the heart prelabeled with [14C]AA, the radiolabeled PC was decreased significantly during reperfusion, associated with a small but significant increase in [14C]AA accumulation. The decreases of PC content and incorporation of [14C]AA into PC, as well as the increases of LPC content and the [14C]AA during reperfusion, were prevented by reperfusion with low Ca2+ (50 microM) buffer or by pretreatment with trifluoperazine (10 microM) or mepacrine (50 microM), but not with verapamil (1 microM). The inhibition of loss of PC was associated with significant diminution of creatine kinase release from the reperfused hearts. The present study indicates that the net loss of membrane phospholipids, especially with respect to PC during reperfusion, may result from 1) inhibition of reacylation of AA, 2) inhibition of de novo synthesis, and 3) stimulation of phospholipase activity. These results are consistent with an influx of Ca2+, although other interpretations are also possible.

Probucol does not affect lipoprotein metabolism in macrophages of Watanabe heritable hyperlipidemic rabbits

We recently reported that the antioxidant action of probucol inhibited the progression of atherosclerosis in Watanabe heritable hyperlipidemic (WHHL) rabbits. In this study, we investigated another possible action of probucol: its action as an antiatherogenic agent on macrophages. When WHHL rabbit peritoneal macrophages were pre-incubated in vitro with probucol and then incubated with several atherogenic lipoproteins, the incorporation of the lipoproteins was not significantly prevented. In the case of mouse peritoneal macrophages, pre-incubation with probucol showed slight, although not statistically significant, changes in the amount of lipoprotein incorporations. We also used macrophages obtained from mice and WHHL rabbits fed with probucol, but the amount of uptake of lipoproteins by these cells was not less than that by control macrophages. Furthermore, to investigate the incorporation of atherogenic lipoproteins into these cells, we prepared probucol-containing macrophages; however, probucol in macrophages failed to prevent the uptake of such lipoproteins. In conclusion, probucol did not prevent foam cell transformation of macrophages of WHHL rabbit or mice directly, and the effect of probucol against atherogenesis in WHHL rabbits was due mainly to its inhibitory effect on the oxidative modification of low density lipoprotein, as previously reported.

A morphological study on the reproductive organs as a possible cause of developmental abnormalities in diabetic NOD mice

The reproductive organs in non-obese diabetic (NOD) mice were histopathologically studied, in order to elucidate the relationships between developmental abnormalities, such as diminished rates of implantation and viable embryos, and structural changes in the reproductive organs. NOD mice with (NOD-DM) and without (NOD-N) diabetes mellitus and ICR mice were compared. The severity of histopathological changes in the pancreas and in the liver were used as parameters which indicated the severity of diabetes itself and of the secondary metabolic disorder. NOD-DM mice exhibited uterine weight loss, accumulation of lipids in luminal and glandular epithelium, atrophies of the endometrium and myometrium and a decrease in the number of muscle cell layers. They also showed a high concentration of lipid droplets in ovarian granulosa cells, atretic follicles and atrophy and lack of lipids in ovarian stroma cells. The severity of these structural changes in the reproductive organs corresponded to those of the changes in the pancreas and the liver. The structural alterations in the ovary suggested disorder in oocyte maturation. The structural changes in the uterus appeared to be related to the decrease in the ratios of implantation and of viable embryos at post-implantation stage. The present studies suggest that the impaired structural environment together with the metabolic environment caused the abnormal development seen, for example, in the oocyte maturation, and at the implantation and post-implantation stage of diabetic mice. It also caused alterations in their hormonal environment.

Host-Specific Effects of Toxin from the Rough Lemon Pathotype of Alternaria alternata on Mitochondria

Host-specific toxin from the rough lemon (Citrus jambhiri Lush) pathotype of Alternaria alternata (ACR toxin) was tested for effects on mitochondria isolated from several citrus species. The toxin caused uncoupling of oxidative phosphorylation and changes in membrane potential in mitochondria from leaves of the susceptible host (rough lemon); the effects differed from those of carbonylcyanide-m-chlorophenylhydrazone, a typical protonophore. ACR toxin also inhibited malate oxidation, apparently because of lack of NAD(+) in the matrix. In contrast, the toxin had no effect on mitochondria from citrus species (Dancy tangerine and Emperor mandarin [Citrus reticulata Blanco], and grapefruit [Citrus paradisi Macf.]) that are not hosts of the fungus. The effects of the toxin on mitochondria from rough lemon are similar to the effects of a host-specific toxin from Helminthosporium maydis (HMT) on mitochondria from T-cytoplasm maize. Both ACR and HMT toxins are highly selective for the respective host plants. HMT toxin and methomyl had no effect (toxic or protective) on the activity of ACR toxin against mitochondria from rough lemon.

Improvement of myocardial function by trifluoperazine, a calmodulin antagonist, after acute coronary artery occlusion and coronary revascularization

Activation of an intracellular calcium-calmodulin complex may play an important role in myocardial injury induced by ischemia and reperfusion. Trifluoperazine, a calmodulin antagonist, was used before ischemia to enhance myocardial preservation by preventing intracellular calcium accumulation. The experimental model used an isolated in situ pig heart (19 control animals and 15 trifluoperazine-treated animals) subjected to occlusion of the left anterior descending coronary artery for 60 minutes followed by 60 minutes of hypothermic potassium crystalloid cardioplegic arrest and 60 minutes of reperfusion. Myocardial segmental function measured by ultrasonic crystals showed that active systolic segment shortening was abolished in the distribution of the left anterior descending artery after 60 minutes of occlusion irrespective of the treatment, whereas that not in the distribution of the left anterior descending artery increased by about 15% in both groups of animals. Restoration of systolic segment shortening in the distribution of the left anterior descending artery 60 minutes after reperfusion was 12% and 42% of baseline levels in untreated and trifluoperazine-treated animals, respectively (p less than 0.01). This improvement in segmental function by trifluoperazine was reflected in significantly (p less than 0.05) better global myocardial contractility and compliance and in significantly (p less than 0.01) greater total coronary blood flow and myocardial oxygen consumption. Trifluoperazine also increased myocardial creatine phosphate content in the distribution of the left anterior descending artery (p less than 0.01) during reperfusion, and creatine kinase release was reduced (p less than 0.05). Our results suggest that trifluoperazine improved regional myocardial function after acute occlusion of the left anterior descending artery and reperfusion and that global cardiac performance was thereby improved. The beneficial effects of trifluoperazine may be exerted by prevention of myocardial injury associated with the calcium-calmodulin complex in ischemic and reperfused myocardium.

[Successful treatment with a small dose of N4-behenoyl-1-beta-D-arabinofuranosylcytosine in a case of chronic myelomonocytic leukemia in blastic crisis]

A 56-year-old female was admitted for the examination of leukocytosis in May, 1982. The hematological examination showed hemoglobin 12.0g/dl, platelets 14.5 X 10(4)/microliters and leukocytes 18,000/microliters with 28% of monocytes. A bone marrow aspiration revealed granulocytic hyperplasia. Granulocytes showed nuclear abnormalities, such as folding or lobulation. From these data, a diagnosis of chronic myelomonocytic leukemia (CMMoL) was made and followed with no treatment for 2 years. However, fever, bone pain, anemia, thrombocytopenia and the increase of monoblasts in the peripheral blood and bone marrow were observed in May, 1984. These findings indicated that she was in the blastic phase. She was treated by intensive combination chemotherapy (BHAC-AMP), but did not attain any remission. Therefore, a small dose of N4-behenoyl-1-beta-D-arabinofuranosylcytosine (BH-AC; 1 mg/kg/day) was administered for 70 days. As a result, complete remission was obtained and continued for 37 months with the same therapy. The experience of this case suggests that small dose of BH-AC could be applied to a case of CMMoL in blastic crisis.

Characterization of very low density lipoprotein from Watanabe heritable hyperlipidemic rabbits

We investigated the properties of very low density lipoprotein (VLDL) from two types of Watanabe heritable hyperlipidemic (WHHL) rabbits: one with a high incidence of coronary atherosclerosis (type 1), and the other with a low incidence (type 2). When incubated with mouse peritoneal macrophages, VLDL from type 1 WHHL rabbit (type 1-VLDL) stimulated cholesteryl ester synthesis 10.5-fold more than VLDL from the type 2 WHHL rabbit (type 2-VLDL) did. Moreover, a similar difference was seen in the stimulation of cholesteryl ester synthesis in peritoneal macrophages isolated from the WHHL rabbits. The mass ratios of cholesterol to protein in type 1- and type 2-VLDL were 5.69 and 2.05, respectively. Agarose gel electrophoresis of type 1-VLDL showed beta mobility, and that of type 2-VLDL showed pre-beta mobility. No difference was seen between the sizes of VLDL particles of the two types. The amount of apolipoprotein E in type 1-VLDL was greater than that in type 2-VLDL. In conclusion, the difference between type 1 and type 2 WHHL rabbits is at least partly due to the presence in type 1 animals of VLDL particles rich in cholesteryl esters and apolipoprotein E, particles which are very similar to beta-VLDL in conformation.

Enhanced myocardial preservation by nicotinic acid, an antilipolytic compound: mechanism of action

The cardioprotective effects of an antilipolytic compound, nicotinic acid, on arrested-reperfused myocardium were investigated in the isolated in situ pig heart preparation. Hearts were preperfused for 15 min in the presence of (5-3H)-glucose and (U-14C)-palmitic acid. Half of the hearts were then perfused with 0.08 mM nicotinic acid for an additional 15-min period, while the remaining control hearts received unmodified perfusion. Arrest was then induced in all animals for 2 h using hypothermic K+ cardioplegia, followed by 60 min of normothermic reperfusion. In control hearts, there were significantly greater levels of long-chain acyl Co-A and acyl carnitine and lower levels of membrane phospholipids than in the nicotinic acid group. While nicotinic acid inhibited beta-oxidation during pre-ischemia and reperfusion, it also prevented the degradation of membrane phospholipids. The net result was a reduction of free fatty acid accumulation during arrest and reperfusion in the nicotinic acid group. Glycolysis, as reflected in 3H2O production, was significantly increased by nicotinic acid administration. In the control heart as compared to the nicotinic acid group, the incorporation of 14C-label from palmitate into triglyceride and cholesterol during arrest was enhanced, while incorporation into phospholipids was depressed. The cardioprotective effects of nicotinic acid were demonstrated by decreased release of creatine kinase and improved coronary blood flow, and cardiac contractility in the reperfused myocardium supplemented with nicotinic acid compared to the control group. These results suggest that nicotinic acid significantly protects the arrested-reperfused myocardium by a) preventing elevation of myocardial fatty acid levels, b) stimulating glycolysis by limiting fatty acid oxidation, c) inhibiting degradation of membrane phospholipids, and d) preventing accumulation of fatty acid metabolites with harmful detergent properties.

Lymphocyte infiltration into cerebellum in transgenic mice carrying human IL-2 gene

We created transgenic mice with an intact human genomic interleukin-2 gene (gIL-2) or a mouse metallothionein-I promoter-human IL-2 chimeric gene (MTgIL-2). Nine (2 gIL-2 and 7 MTgIL-2 transgenics) out of 12 transgenic mice which were obtained independently had motor ataxic symptoms. All transgenic offspring of the symptomatic founders showed the same symptoms as their transgenic parents. Morphological examination demonstrated perivascular lymphocyte accumulation in the cerebellar meninx which was followed by increased cell infiltration of neutrophils and monocytes in the destructive cerebellum of all transgenic mice. These findings suggest that the lymphocyte infiltration in the cerebellum is caused by the specific effect of the exogenously introduced human IL-2 gene.

Improved myocardial performance induced by clofibrate during reperfusion after acute myocardial infarction

The increase of cellular fatty acids appears to be one of the causes of the myocardial injury during ischemia and reperfusion. This study was designed to examine whether a hypolipidemic drug such as clofibrate can reduce the myocardial injury during ischemia and reperfusion. Clofibrate was fed to experimental pigs for 9 days. Isolated in situ hearts from both experimental and control pigs were subjected to 60 min of regional ischemia induced by occluding the left anterior descending coronary artery, followed by 60 min of global ischemia by hypothermic cardioplegic arrest and 60 min of reperfusion. The clofibrate feeding resulted in the better cardiac performance as judged by increased coronary blood flow, improved left ventricular function, and reduced myocardial injury as judged by creatine kinase release. Although the clofibrate-fed animals contained higher levels of thiobarbituric reactive materials, the free fatty acid levels of plasma and myocardium were much lower compared with control animals. The clofibrate feeding was also associated with increased peroxisomal catalase and beta-oxidation of fatty acids. These results suggest that decreased levels of free fatty acids in the plasma and the myocardium and increased catalase activity induced by antilipolytic therapy appear to provide beneficial effects to the myocardium during ischemia and reperfusion.

Enhanced phosphodiesteratic breakdown and turnover of phosphoinositides during reperfusion of ischemic rat heart

In this study, we examined phosphoinositide metabolism during ischemia and reperfusion using an isolated and perfused rat heart. When myocardial phosphoinositides were prelabeled with [3H]inositol, reperfusion after 30 minutes of normothermic global ischemia resulted in significant accumulations of radiolabeled inositol phosphate, inositol bisphosphate, and inositol trisphosphate. Isotopic incorporation of [3H]inositol into phosphatidylinositol, phosphatidylinositol-4-phosphate, and phosphatidylinositol-4,5-bisphosphate was increased significantly in the heart reperfused with [3H]inositol after 30 minutes of ischemia compared with that perfused with [3H]inositol after 30 minutes of nonischemic perfusion. However, isotopic incorporation of [3H]glycerol into diacylglycerol, phosphatidic acid, and all of the three phosphoinositides was diminished in the reperfused hearts. Reperfusion of the ischemic heart prelabeled with [14C]arachidonic acid resulted in significant increases in [14C]diacylglycerol and [14C]phosphatidic acid. The enhanced accumulations of [3H]inositol phosphates during reperfusion were not affected by treatment with prazosin plus atropine or indomethacin, but were inhibited by hypoxic reperfusion, reperfusion with Ca2+-free buffer, or by mepacrine. These results suggest that myocardial reperfusion stimulates phosphodiesteratic breakdown and turnover of phosphoinositides, and increased Ca2+ influx caused by reperfusion may be involved in the mechanism of stimulation of phosphatidylinositol-specific phospholipase C activity in the rat heart.

Development of mitochondrial helical sheath in the middle piece of the mouse spermatid tail: regular dispositions and synchronized changes

Morphologic changes in the development of the mitochondrial helical sheath in the mouse spermatid tail were examined with the scanning electron microscope (SEM) using the osmium-DMSO-osmium method and classified into several stages. During late spermiogenesis, spherical mitochondria gathered around the forming spermatid tail. The shape of these mitochondria gradually changed from spheroid to long and rod-like. Mitochondria first were arranged in four longitudinal rows (stage 1) that twisted dextrally, and the mitochondria began to stagger (stage 2). They became elongated and arranged into a staggered pattern; they then attached to each other in an end-to-end fashion to form a sinistral double helix around the core of the axoneme (stage 3). These end-to-end contacts were observed in every second gyre on the four lines surrounding the core of the axoneme at stage 3. Mitochondria further elongated and end-on touching appeared with every third gyre on the five longitudinal lines that surround the core of the axoneme (stage 4). The direction of the helix, always sinistral, was clearly discernible only in the later stages. Disposition of the mitochondria in the spermatid tail was regular throughout development, which indicates that these mitochondria elongate simultaneously and also at the same rate. On any given cracked surface of the seminiferous tubule, spermatid tails with the same stage of mitochondria predominantly were observed. This ultrastructural finding appears compatible with the histologic synchronism, (termed the "wave") in differentiating germ cells.

Enhanced myocardial preservation by nicotinic acid, an antilipolytic compound. Improved cardiac performance after hypothermic cardioplegic arrest

The effect of nicotinic acid, an antilipolytic drug, on myocardial preservation was studied on the basis of cardiac performance after 2 hours of cardioplegic arrest. Isolated in situ pig hearts were subjected to 120 minutes of hypothermic potassium (35 mEq) crystalloid cardioplegic arrest followed by 60 minutes of reperfusion. The experimental group received nicotinic acid 0.08 mmol/L 15 minutes before cardioplegic arrest, whereas the control group received 15 minutes of unmodified perfusion. There was a marked decline in myocardial creatine phosphate levels during cardioplegic arrest in both groups that returned to the baseline level during reperfusion without a significant intergroup difference, and adenosine triphosphate levels remained stable throughout the experiment in both groups. Myocardial oxygen consumption during reperfusion was significantly higher in hearts treated with nicotinic acid, which was consistent with a significantly greater cardiac contractile force as evaluated by isovolumetric left ventricular pressure measurements. There appeared to be less cardiac membrane damage as measured by creatine kinase release during reperfusion, which was significantly inhibited by treatment with nicotinic acid. The present study supports the conclusion that nicotinic acid improves cardiac performance after hypothermic cardioplegic arrest.

Alkaline phosphatase activity of the IVth ventricular choroidal epithelium of rats during embryonic and neonatal development

The cytochemical localization of alkaline phosphatase (AlPase) activity in the developing IVth ventricular choroidal epithelium was investigated in embryonic and neonatal rats. During the initial development of the choroidal primodium the flattened and/or cuboidal epithelial cells of the ventricular roof were changed to columnar cells with well-developed microvilli and apical tight junctions. When compared to AlPase activity on the lateral plasma membranes of the surrounding ependymal cells, these columnar cells of the choroidal primodium revealed activity on the lateral and luminal plasma membranes, but no activity was found on the basal surface of these cells. On the other hand, the epithelial cells in the neonatal choroid plexus showed a continuous morphological alteration from columnar cells with short microvilli to mature cuboidal cells with numerous long microvilli. AlPase activity in immature columnar cells was observed on all plasma membranes, except for the apical junctional area of the lateral surface. With maturing of the choroidal epithelial cells, the activity appeared to be eliminated from the lateral and luminal plasma membranes of the cuboidal cells, and mature choroidal epithelial cells showed activity on the basal surface only. These findings suggest that AlPase may play an important role in the membrane activity of epithelial cells differentiating between the primitive epithelial cells of the ventricular roof and the mature choroidal epithelial cells.

The effect of temperature and hematocrit level of oxygenated cardioplegic solutions on myocardial preservation

The ideal temperature and hematocrit level of blood cardioplegia has not been clearly established. This study was undertaken (a) to determine the optimal temperature of blood cardioplegia and (b) to study the effect of hematocrit levels in blood cardioplegia. A comparison of myocardial preservation was done among seven groups of animals on the basis of variations in hematocrit levels and temperature of oxygenated cardioplegic solution. The experimental protocol consisted of a 2-hour hypothermic cardioplegic arrest followed by 1 hour of normothermic reperfusion. Group 1 received oxygenated crystalloid cardioplegic solution at 10 degrees C. Groups 2 through 7 received oxygenated blood cardioplegic solution with the following hematocrit values and temperatures: (2) 10%, 10 degrees C; (3) 10%, 20 degrees C; (4) 10%, 30 degrees C; (5) 20%, 10 degrees C; (6) 20%, 20 degrees C; and (7) 20%, 30 degrees C. Parameters studied include coronary blood flow, myocardial oxygen extraction, myocardial oxygen consumption, and myocardial high-energy phosphate levels of adenosine triphosphate and creatine phosphate during control (prearrest), arrest, and reperfusion. Myocardial oxygen consumption at 30 degrees C during arrest was significantly higher than at 10 degrees C and 20 degrees C, which indicates continued aerobic metabolic activity at higher temperature. Myocardial oxygen consumption and the levels of adenosine triphosphate and creatine phosphate during reperfusion were similar in all seven groups. Myocardial oxygen extraction (a measure of metabolic function after ischemia) during initial reperfusion was significantly lower in the 30 degrees C blood group than in the 10 degrees C blood group at either hematocrit level and in the oxygenated crystalloid group, which suggests inferior preservation. The hematocrit level of blood cardioplegia did not affect adenosine triphosphate or myocardial oxygen consumption or extraction. It appears from this study that blood cardioplegia at 10 degrees C and oxygenated crystalloid cardioplegia at 10 degrees C are equally effective. Elevating blood cardioplegia temperature to 30 degrees C, however, reduces the ability of the solution to preserve metabolic function regardless of hematocrit level. Therefore, the level of hypothermia is important in blood cardioplegia, whereas hematocrit level has no detectable impact, and cold oxygenated crystalloid cardioplegia is as effective as hypothermic blood cardioplegia.

Positive inotropic effect and phosphoinositide breakdown mediated by arachidonic acid and prostaglandin F2 alpha

We investigated the mechanism of arachidonate- and prostaglandin-induced alteration of cardiac contractile activity in isolated rat left ventricular papillary muscles. Superfusion with 10(-6) to 10(-4) M arachidonic acid resulted in a slow developing positive inotropic effect (PIE) in a concentration-dependent manner. The PIE was abolished by pretreatment with 10(-5) M indomethacin. Prostaglandin (PG) F2 alpha also produced a significant PIE in a concentration-dependent manner, but the EC50 value was approximately 2 orders of magnitude lower and the maximum contractile response was 2-fold higher than those of arachidonate. PGE2 and PGI2 were without an effect on contractile force at concentrations ranging from 10(-9) to 10(-6) M. Both arachidonate and PGF2 alpha provoked slow responses in the partially depolarized muscles in a time course similar to that of development in the PIE. Neither arachidonate nor PGF2 alpha affected tissue levels of cyclic AMP and cyclic GMP, but these molecules increased accumulations of [3H]inositol phosphates (IPs) in a concentration-dependent manner similar to that observed for their PIE. The enhanced accumulation of [3H]IPs induced by arachidonate was abolished by pretreatment with 10(-5) M indomethacin. Although an increase in [3H]IP level was relatively rapid in PGF2 alpha-treated tissues, maximum accumulations of [3H]IPs were identical between arachidonate- and PGF2 alpha-treated tissues. Thus, for comparable increases in [3H]IPs, there was a greater PIE with PGF2 alpha than with arachidonate.(ABSTRACT TRUNCATED AT 250 WORDS)

Judgments of horizontality of still water: effects of perceptual and cognitive factors

Three experiments examined failure to solve the Piagetian water-level horizontality task in terms of artifacts of experimental procedure, perceptual characteristics of the task, and the physical principles involved in the task. The possibility that rotational set accounts for task failure was examined in Exp. 1 (N = 154 college students) with no evidence of an effect, although the spatial tasks used correlated with performance on the horizontality task for women but not for men. In Exp. 2 (N = 159) a procedure of focussing attention on the movement of water and air using a carpenter's level also did not affect horizontality performance. However, Exp. 3 confirmed that performance (N = 57) on the horizontality task was related to understanding the basic principle of the level. These results were discussed in terms of possible experiences of the subjects as well as the relative contributions of perceptual and cognitive factors.

Alpha 1-adrenoceptor-mediated phosphoinositide breakdown and inotropic response in rat left ventricular papillary muscles

alpha 1-Adrenoceptor stimulation of rat left ventricular papillary muscles by phenylephrine in the presence of propranolol resulted in rapid breakdown of phosphatidylinositol 4,5-bisphosphate (PI-4,5-P2) and a triphasic inotropic response in a concentration-dependent manner. The release of inositol trisphosphate (IP3) was maximum within 30 seconds and remained high for at least 30 minutes. The IP3 formation was associated with a rapid, but small, increase in contractile force followed by a transient decline in the contractility prior to the development of a sustained and more pronounced positive inotropic response. Inhibition of PI-4,5-P2 hydrolysis by the alpha 1-adrenergic antagonist prazosin or the PI-4,5-P2 phosphodiesterase inhibitor neomycin blocked all components of the inotropic responses. Combined addition of 2,3-diphosphoglyceric acid, a competitive inhibitor of IP3 phosphatase, with phenylephrine doubled the IP3 formation and potentiated the initial phases of inotropic responses but had no effect on the sustained positive inotropic response. Nifedipine and Mn2+ did not block the transient inotropic responses but inhibited the sustained positive inotropic response. alpha 1-Adrenoceptor stimulation resulted in restoration of slow responses in the high K+-depolarized muscles in the time course similar to that of the development in the sustained positive inotropic response. Addition of phorbol-12,13-dibutyrate alone or in combination with caffeine or A23187 failed to produce a sustained positive inotropic effect, but pretreatment with this phorbol ester (1-100 nM) for 30 minutes resulted in dose-dependent potentiation of alpha 1-adrenoceptor-mediated sustained positive inotropic effect associated with enhanced slow responses. These results suggest that the inotropic effects mediated by cardiac alpha 1-adrenoceptor stimulation occur through the phosphodiesteratic cleavage of PI-4,5-P2, such that IP3 may produce transient inotropic effects by mobilizing intracellular Ca2+, while diacylglycerol, along with cofactors that are also generated on alpha 1-adrenoceptor stimulation, may provoke a sustained positive inotropic effect by potentiating slow Ca2+ channels through activation of protein kinase C.

Development of the choroid plexus anlage and supraependymal structures in the fourth ventricular roof plate of human embryos: scanning electron microscopic observations

The developing anlage of the choroid plexus and supraependymal structures in the fourth ventricular roof plates of nine normal human embryos ranging from Carnegie stages 14 to 19 were investigated with scanning electron microscopy. In the human embryos at stage 18, the first semimacroscopic choroidal anlage developed in the form of bilateral evaginations that ran dorsomedially and caudally from the bilateral corners of the rhombencephalon. The anlage became evident with even smaller and parallel ridges in the embryo at stage 19. Embryos at earlier stages exhibited surface membrane modifications such as convexity, microvilli, cilia, and spherical protrusions at the middle one-third of the rhombencephalon, which corresponded to the future choroidal anlage region. Two morphologically different groups of supraependymal cells (SE cells) were elucidated throughout the stages examined. Type 1 SE cells has spindle or tear-drop-like bodies, frequently with one or more long cytoplasmic processes. Type 2 SE cells were globular, with numerous fine pseudopodial processes. Type 1 SE cells were distributed mainly at the future choroidal anlage regions or on the anlage itself and were less frequently located at the rostral end of the roof. We found no general pattern in the distribution of type 2 SE cells. Supraependymal fibers (SE fibers) were seen as fine processes that were distributed similarly to type 1 SE cells and extended transversely for a long distance.

The mechanism of myocardial reperfusion injury in neonates

Oxygen free radicals and phospholipid degradation have been implicated in the pathogenesis of ischemia and reperfusion injury. The present study examines the involvement of such mechanisms in myocardial reperfusion injury in neonatal hearts. The isolated neonatal pig hearts from two different age groups, 0 to 2 days old (newborn) and 7 to 9 days old (week-old), were subjected to 60 min of normothermic global ischemia followed by 60 min of reperfusion. Although myocardial ischemia reduced superoxide dismutase, catalase, and glutathione peroxidase activities in both age groups, superoxide dismutase and catalase activities remained significantly lower in the newborn pig heart during ischemia and reperfusion. Oxidized glutathione release from the neonatal pig hearts was at minimum levels before ischemia, but it increased 10-fold at the onset of reperfusion and was significantly higher in the newborn heart. This indicates that generation of oxygen free radicals was enhanced in the newborn compared with that in the week-old heart. The increase in phospholipase A2 activity and decrease in acyl CoA synthetase and lysophosphatidylcholine acyl transferase activities during ischemia and reperfusion were associated with comparable loss of membrane phospholipids and accumulation of lysophosphatidylcholine and free fatty acids in both age groups, except that oleic acid content was significantly higher in the newborn heart during reperfusion. Myocardial damage appears to be potentiated in the newborn heart during reperfusion, as evidenced by higher release of creatine kinase and a lower content of high-energy phosphates. These results indicate that oxygen free radicals may play a crucial role in the occurrence of reperfusion injury in immature hearts.

Role of xanthine oxidase inhibitor as free radical scavenger: a novel mechanism of action of allopurinol and oxypurinol in myocardial salvage

Xanthine oxidase (XO) has been hypothesized to be a potential source of oxygen-derived free radicals during reperfusion of ischemic myocardium based on the fact that allopurinol, a XO-inhibitor, can reduce reperfusion injury. In this communication we report that both allopurinol and oxypurinol, the principle metabolite of allopurinol, prevent the reperfusion injury in isolated pig heart. However, we found that neither pig heart nor pig blood contain any XO activity. Our study showed a direct free radical scavenging action of these XO-inhibitors during ischemia and reperfusion, as judged by the reduction of free radical signals when compared using an Electron Paramagnetic Resonance Spectrometer. Using a Luminometer, we also confirmed that both allopurinol and oxypurinol can scavenge ClO2, HOCl, and significantly inhibit free radical signals generated by activated neutrophils. These XO-inhibitors, however, failed to scavenge O2. and OH. radicals. Our results suggest that these XO-inhibitors salvaged the ischemic-reperfused myocardium by scavenging free radicals, and not by inhibiting XO in the pig heart.