Linkage analysis of infantile pyloric stenosis and markers from chromosome 9q11-q33: no evidence for a major gene in this candidate region

In order to investigate useful indicators of lead contamination, 108 Japanese Black calves from a lead-contaminated farm were used. The lead concentrations in blood (Ph-B), delta-aminolevulinic acid dehydratase (ALA-D) activities, and free erythrocyte protoporphyrin (FEP) concentrations were examined. A significant negative correlation was obtained between Pb-B concentrations and ALA-D activities (r = -0.621, p < 0.01). A significant positive correlation was obtained between Ph-B concentrations and FEP concentrations (r = 0.850, p < 0.01). The calves were divided by Pb-B concentrations (micrograms/100 ml) into 5 groups (A = < or = 30, B = 31 approximately 90, C = 91 approximately 150, D = 151 approximately 210, E = > or = 211) to observe the relation of ALA-D activities, FEP concentrations and ALA-D activities in group B (r = -0.706, p < 0.05). A significant positive correlation was obtained between Pb-B concentrations and FEP concentrations in groups A, B and D (A = r = 0.496, p < 0.01; B = r = 0.686, p < 0.01; D = r = 0.529, p < 0.05). These results indicate that FEP concentrations were good indicators of lead contamination.     

Comparative studies of O,O-dialkyl-O-chloromethylchloroformimino phosphates: interaction with neuropathy target esterase and acetylcholinesterase

Acetylcholinesterase (AChE) and neuropathy target esterase (neurotoxic esterase, NTE) are two major target enzymes for organophosphorus (OP) esters. The relative potency of an OP ester to react with AChE or with NTE in vitro correlates with its relative potency in vivo to cause acute toxicity (death) or organopohosphate-induced delayed neurotoxicity (OPIDN). On this basis extrapolation from in vitro to in vivo data now seems justifiable to predict risk of OPIDN. The kinetics of NTE and AChE inhibition by experimental pesticides of the general formula (RO)2P(O)ON=CClCH2Cl, where R = methyl, ethyl, isopropyl, propyl, isobutyl, butyl, pentyl, has been studied. Compounds with short R (methyl, ethyl) were shown to be far more potent inhibitors of AChE than NTE. Both anti-NTE activity, selectivity for NTE and, correspondingly, the propensity of compounds to cause OPIDN rise with increasing their hydrophobicity. A high value of ki(NTE)/ki(AChE) for R = pentyl suggests that this compound would have the potential to cause OPIDN at doses lower than the LD50. A quantitative structure-activity relationships (QSAR) analysis indicated that NTE and AChE have different structural and electronic requirements for their respective OP inhibitors.     

Effects of nitric oxide on neuroendocrine function and behavior

Nitric oxide (NO) is an unusual chemical messenger. NO mediates blood vessel relaxation when produced by endothelial cells. When produced by macrophages, NO contributes to the cytotoxic function of these immune cells. NO also functions as a neurotransmitter and neuromodulator in the central and peripheral nervous systems. The effects on blood vessel tone and neuronal function form the basis for an important role of NO on neuroendocrine function and behavior. NO mediates hypothalamic portal blood flow and, thus, affects oxytocin and vasopression secretion; furthermore, NO mediates neuroendocrine function in the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axes. NO influences several motivated behaviors including sexual, aggressive, and ingestive behaviors. Learning and memory are also influenced by NO. Taken together, NO is emerging as an important chemical mediator of neuroendocrine function and behavior.     

Comparison of the sensitivity of three psychophysical techniques to three manual materials handling task variables

Nitric oxide is hypothesized to be an inhibitory modulator of central sympathetic nervous outflow, and deficient neuronal nitric oxide production to cause sympathetic overactivity, which then contributes to nitric-oxide-deficient hypertension. The biochemical and neuroanatomical basis for this concept revolves around nitric oxide modulation of glutamatergic neurotransmission within brainstem vasomotor centers. The functional consequence of neuronal nitric oxide in blood pressure regulation is, however, marked by an apparent conflict in the literature. On one hand, conscious animal studies using sympathetic blockade suggest a significant role for neuronal nitric oxide deficiency in the development of nitric-oxide-deficient hypertension, and on the other hand, there is evidence against such a role derived from 'knock-out' mice lacking nitric-oxide synthase 1, the major source of neuronal nitric oxide.     

A comparative study of the interaction of phosphoric acid dichlorovinyl esters with a neurotoxic esterase from the brain of hens and rats

In order to validate a rodent biochemical model of delayed neurotoxicity of organophosphates (OP) inhibition of rat and hen brain neurotoxic esterase (NTE) by some dichlorovinyl phosphates and phosphonates was studied in vitro and in vivo. It was shown that compounds investigated exhibited the similar inhibitory potency to NTE from both species in vitro, in addition rat and hen NTE showed the same sensitivity to variation of the structure of OP inhibitors. A good correlation was found between pI50 estimated with enzymes from rat and hen trains: r2 = 0.951, n = 18, p < or = 0.05. NTE activities were also measured in rat and hen brains after acute administration of various dosages of potent axonopathic compound dipropyldichlorovinyl phosphate. The results obtained indicate that difference in species susceptibility to neurotoxic action of OP, in particular the absence of ataxia in rats, is not caused by difference in target enzyme sensitivity to axonopathic organophosphates.     

A review of nonpesticide phosphate ester-induced neurotoxicity in cattle

Nonpesticide phosphate esters induce delayed neurotoxicity in cattle. The most common exposures are to complex mixtures of triaryl phosphate used in lubricating oils. Oral ingestion is most common, but dermal exposures have also occurred. Clinical signs of cholinesterase (ChE) inhibition may or may not be seen. Depending on the biochemical targets, the percent reduction in blood ChE is variable and can be < 30% of normal activity. Organophosphate ester-induced delayed neurotoxicity cannot be predicted by inhibition of blood ChEs. Signs of delayed neurotoxicity occur 2 to 25 d after exposure; these signs are neurologic deficiencies of the antigravity muscles and the muscles of the urinary bladder and larynx. Affected cattle may dribble urine and some may be mute. Signs of ChE inhibition generally are not observed in animals with neurological deficiencies. Pathologic findigs are axonopathy and myelin degeneration of nerves with long axons located in both the peripheral and central nervous systems. In the spinal cord, location of the affected nerve tracts is variable. Degenerative changes occur in motor neurons. Calves are less susceptible to organophosphate ester-induced delayed neurotoxicity than cows. A dose of 500 mg triaryl phosphate/kg body weight will produce complete paralysis in a mature cow in 26 d.     

Manipulation of knee extensor force using percutaneous electrical myostimulation during eccentric actions: effects on indices of muscle damage in humans

In Hirschsprung's disease (HD), certain intestinal nervous plexuses are absent. Sprouting nerve endings contain different amounts of synaptophysin (SY), a protein and main constituent of acetylcholinesterase (AChE) storage compartments. Due to the lack of specific markers for synapses, a qualitative analysis of nerve endings of intestinal segments affected by HD has not yet been undertaken. For this study, resected colorectal specimens from patients with HD (n = 8, mean age 2.1 years) were investigated in parallel for AChE, SY, and content of small synaptic vesicles by biochemical, immunohistochemical, and electronmicroscopic means. In the microdissected muscular layer, reduced SY (1.4 microgram/mg total protein, normal 24 +/- 0.3) was observed. Immunohistochemistry showed in affected tissues reduced numbers of SY-positive nerve fibers and nerve endings, which in turn were thickened and distorted, in both the muscle proper and the muscularis mucosae. Combining both morphologic and biochemical findings, in HD the number of cholinergic vesicles in the remaining nerve endings seems to be increased as measured by SY, a marker molecule specific for synaptic vesicles. Our data also suggest that nerve endings in HD may contain high concentrations of cholinergic vesicles, paralleling the known high amounts of acetylcholine and AChE found in intestinal segments of patients with HD.     

Mercury content in skin-lightening creams and potential hazards to the health of Saudi Women

Neuropathy target esterase (NTE) is inhibited by many organophosphorus compounds that induce delayed neuropathy. This study examines two of the most potent NTE inhibitors, 2-octyl-4H-1,3,2-benzodioxaphosphorin 2-oxide (OBDPO) and ethyl octylphosphonofluoridate (EOPF), in cell lines with neural properties (PC-12 and NB41A3) and of nonneural origin (C6 and HeLa). NTE-like esteratic activity is higher in PC-12, HeLa and C6 cells than in NB41A3 cells and in each case is inhibited 50% by OBDPO and EOPF at 0.03-3.4 nM in vitro and by OBDPO at 0.080-36 nM in situ in culture. An NTE-like protein(s) of about 155 kDa is phosphorylated and labeled by [3H-octyl]OBDPO in these cell lines in the same order as their relative NTE esteratic activity. Cytotoxic levels of OBDPO and EOPF (300-500 microM) are generally 10(5) to > 10(7)-fold higher than required for NTE inhibition. PC-12 cells and OBDPO/[3H]OBDPO and EOPF are therefore suitable for research on non-lethal biochemical disruptions from NTE phosphorylation and aging.     

The human placenta's lead level as a parameter of the ecological lead exposure. Its validity in comparison to the lead level in blood, the activity of the delta-aminolevulinic acid dehydratase and the concentration of the free erythrocyte porphyrins of newborns and their mothers (author's transl)

In order to estimate the ecological exposure of lead, placenta- and blood-investigations were made at four collectives from variously industrialized regions (Ruhrregion, Middle Frankonia Centre, Bavarian Forest). 148 normal births and 19 premature births (in each case mothers and newborns) were listed as well as twelve abortions. We investigated the lead-level in blood, the activity of delta-aminolaevulinic acid dehydratase (ALA-D) the concentration of free erythrocyte porphyrine (FEP) and the placentas' lead concentration. Though in the Ruhrregion (Dortmund) significantly higher lead levels in blood were found compared to the Bavarian Forest, the results together, were in the normal range, less than 35 mug%. In an average the mothers' lead level in blood was around 1.4 times (ca. 5 mug%) above that of their newborns; analysing this statistically, highly significant correlations were found. However for the ALA-D activity and the FEP-results no direct dependence of the lead levels in blood could be found. In the placentas mean lead concentrations between 1.94 mug and 2.23 mug per gram dry-weight (30.6 mug-38.9 mug/100 g wet-weight) were gained. In the contrary to the measured results of lead in blood the average placentas' lead level of the most and least industrialized regions were almost identical. A correlation between the mothers' respectively their children's lead levels in blood and the placental lead concentrations could not be proved. No relation could be found between the results and the gestation ages. As final results: 1. The placenta is no ideal investigation object concerning the environment's lead exposure. 2. It has no special barriere - or depot - function in lead metabolism. 3. In order to estimate the environment's lead exposure the determination of the lead level in blood will also be in future the optimal method. This investigation is of special value because of its validity of the results and the practicability of winning the samples compared to other parameters and biological materials.     

Interstitial cells of Cajal: mediators of communication between circular and longitudinal muscle layers of canine colon

Autopsy studies of patients with AIDS dementia have shown neuronal loss consistent with a neurotoxic component of this disease. In vitro studies suggest that viral products or cytokines from HIV-infected macrophages (Mphi) may modulate or directly mediate excitotoxic cell death of neurons. Mphi differentiated from peripheral mononuclear blood cultures were infected with HIV, and conditioned media (CM) were harvested from these cultures. Exposure of SK-N-MC (neuroblastoma) cells to CM from HIV-infected Mphi for 4, 24 or > or = 48 h resulted in a mean suppression of 12-34% of the glutamate transport Vmax with no appreciable change in transport Km. An astrocytoma tumor cell, U373MG, showed similar CM-mediated glutamate uptake suppression. Changes were evident in total and Na+-dependent glutamate uptake, with significantly more suppression of Na+-dependent uptake. Similar effects were seen with the nonmetabolizable transporter agonist D-aspartate, indicating that the effect was on transport and not metabolism. No suppression was seen with CM from uninfected Mphi or Mphi infected with heat-inactivated HIV. The magnitude of uptake suppression was not correlated with CM p24 values, and removal of CM virions by ultracentrifugation and immunoprecipitation did not alter the uptake-suppressive properties of infected Mphi CM. Uptake suppression was seen when Mphi were infected with Mphi-tropic strains HIV(SF162), HIV(JR-CSF), HIV(NFN-SX) and a Mphi-tropic patient isolate, but not the lymphotropic strain HIV(LAI). HIV-infected Mphi may produce substances which suppress neuronal and glial glutamate neurotransmitter uptake, resulting in higher extracellular glutamate levels and leading possibly to deficits in cell signaling and neurotoxicity.     

Rapid desensitization determines the pharmacology of glutamate neurotoxicity

Glutamate (Glu), the major excitatory neurotransmitter in the nervous system, is toxic to neurons when it accumulates at high concentrations in the extracellular space. Even though Glu is a mixed agonist, capable of activating N-methyl-D-aspartate (NMDA) receptors and non-NMDA receptors, in many preparations Glu neurotoxicity is prevented by selective blockade of NMDA receptors. In cultures of hippocampal neurons, treatment with 500 microM Glu for 30 min killed more than 90% of the neurons. The simultaneous addition of the selective NMDA agonist methyl-10,11-dihydro-5-H-dibenzocyclo-hepten-5,10-imine (MK-801) reduced the cell loss to less than 30%. However, when Glu was combined with either diazoxide or cyclothiazide, two thiazides which dramatically diminish rapid Glu desensitization, MK-801 was no longer very protective and neuronal loss exceeded 80%. However, the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), in combination with MK-801, was able to prevent most Glu neurotoxicity in the presence of these thiazides. These experiments show that there are circumstances under which Glu neurotoxicity is produced by overactivation of non-NMDA receptors. Our observations offer a possible explanation for the recent finding that blockade of non-NMDA receptors is much more beneficial than NMDA receptor blockade in protecting the brain in some in vivo models of global ischemia.     

Occult pneumococcal septicemia and pneumococcal pneumonia complicating pneumatoceles in a previously healthy child

1. The effect of in vitro glycation on delta-aminolevulinic dehydratase (ALA-D) under several experimental conditions was investigated. When preincubated with 500 mM glucose at 37 degrees C for 20 hr, ALA-D was 80% inactivated and glycated hemoglobin levels were increased more than fourfold. 2. Thiobarbituric acid species were not modified during glycation; therefore ALA-D inactivation cannot be attributed to glucose autoxidation. 3. Acetyl salicylic acid was effective in preventing both hemoglobin glycation and ALA-D inactivation by glucose. 4. A method has been developed for measuring protein glycation in vitro, in a crude preparation of red blood cells, which can also be applied to sugars other than glucose.     

Distribution of butyrylcholinesterase in the human amygdala and hippocampal formation

The distribution of the major cholinergic regulatory enzyme acetylcholinesterase (AChE, EC 3.1.1.7) has been extensively studied in the human brain, but the distribution of the closely related enzyme butyrylcholinesterase (BuChE, EC 3.1.1.8) is largely unknown. Because of the importance of BuChE and AChE in Alzheimer's disease, we have studied the distribution of BuChE in the normal human amygdala and hippocampal formation and compared it with that of AChE by using histochemical techniques. In the amygdala, the distribution of BuChE differed significantly from that of AChE in that BuChE was found primarily in neurons and their dendritic processes, whereas AChE was found predominantly in the neuropil. BuChE-positive neurons were present in up to 10% of the neuronal profiles in lateral, basolateral (basal), basomedial (accessory basal), central, cortical, and medial amygdaloid nuclei. AChE was found primarily in the neuropil in these nuclei with only a few AChE-positive neurons. In the hippocampal formation, BuChE was also found in neurons and not in the neuropil, whereas AChE was found in both neurons and in the neuropil. BuChE and AChE neurons were present in the polymorphic layer of the dentate gyrus, as well as the stratum oriens and stratum pyramidale of the hippocampus proper. There was considerable overlap in shapes, sizes, and numbers of BuChE- and AChE-positive neurons, suggesting that the enzymes were colocalized in neurons of the hippocampal formation. The distinct distribution of BuChE suggests that it may have specific functions including coregulation of cholinergic and noncholinergic neurotransmission in human amygdala and hippocampal formation.     

Stable complexes involving acetylcholinesterase and amyloid-beta peptide change the biochemical properties of the enzyme and increase the neurotoxicity of Alzheimer's fibrils

Brain acetylcholinesterase (AChE) forms stable complexes with amyloid-beta peptide (Abeta) during its assembly into filaments, in agreement with its colocalization with the Abeta deposits of Alzheimer's brain. The association of the enzyme with nascent Abeta aggregates occurs as early as after 30 min of incubation. Analysis of the catalytic activity of the AChE incorporated into these complexes shows an anomalous behavior reminiscent of the AChE associated with senile plaques, which includes a resistance to low pH, high substrate concentrations, and lower sensitivity to AChE inhibitors. Furthermore, the toxicity of the AChE-amyloid complexes is higher than that of the Abeta aggregates alone. Thus, in addition to its possible role as a heterogeneous nucleator during amyloid formation, AChE, by forming such stable complexes, may increase the neurotoxicity of Abeta fibrils and thus may determine the selective neuronal loss observed in Alzheimer's brain.     

Leukemia inhibitory factor-dependent transcriptional activation in embryonic stem cells

Glutamate (Glu) is a major excitatory amino acid neurotransmitter in the mammalian brain. Under Certain Circumstances Glu can also exert toxic effects on neuronal Cells. To unravel the biochemical mechanisms of Glu-induced acute neuronal injury, Glu 1 mumol/1 mul was microinjected into cerebral Cortex, striatum and hippocampus of adult rats and oxidative stress and antioxidant parameters were evaluated. The results show that the rate of lipid peroxidation was significantly increased in the above brain regions following Glu administration suggesting neuronal membrane damage and also the total and free sulfhydryl groups were significantly depleted, indicating altered red-ox status of the cells. There was also alteration in the activity of antioxidant enzyme catalase in cerebral cortex. Some of the above Glu-induced effects were reversed or modified by NMDA receptor antagonist MK-801.     

Organophosphate-induced acetylcholinesterase inhibition and embryonic retinal cell necrosis in vivo in the teleost (Oryzias latipes)

Recent monitoring of the Sacramento-San Joaquin River system (CA) indicates that levels of the organophosphate pesticide, diazinon, exceed National Academy of Science guidelines and these levels result in toxicity in USEPA acute toxicity tests with Ceriodaphnia dubia. Since organophosphates (OPs) inhibit acetylcholinesterase (AChE), the present study examined the effects of diazinon on the embryonic nervous system of a model teleost, medaka, Oryzias latipes. Preliminary histological screens revealed limited retinal cell necrosis in control embryos with apparent increased necrosis in diazinon-exposed embryos. Subsequently, embryos were exposed to 1.8 x 10(-5), 4.4 x 10(-5), or to 8.8 x 10(-5) M diazinon and replicates were frozen for biochemical analysis or were fixed for histopathological analysis at days 3, 5, and 7 of development. Diazinon exposure significantly inhibited AChE activity within whole embryos and in homogenates of retinas from treated animals. Histological examination of embryos indicated that as the retina underwent differentiation into distinct cell layers, between days 5 and 7, small foci of necrotic cells became apparent within the inner nuclear layer and isolated individual pyknotic cells were observed in the ganglion layer. Quantification of foci of necrotic cells revealed that 8.8 x 10(-5) M diazinon increased number and area of these lesions. Enzyme histochemistry localized AChE activity to regions equivalent to sites of necrosis. Separate exposures of embryos to the OP, diisopropylphosphorofluoridate, produced large foci of necrotic cells at sites equivalent to those seen following diazinon exposure.     

Neurosteroids: a novel function of the brain

Neurosteroids are synthetized in the central and peripheral nervous system, particularly but not exclusively in myelinating glial cells, from cholesterol or steroidal precursors imported from peripheral sources. They include 3-hydroxy-delta 5-compounds, such as pregnenolone (PREG) and dehydroepiandrosterone (DHEA), their sulfates, and reduced metabolites such as the tetrahydroderivative of progesterone 3 alpha-hydroxy-5 alpha-pregnane-20-one (3 alpha, 5 alpha-TH PROG). These compounds can act as allosteric modulators of neurotransmitter receptors, such as GABAA, NMDA and sigma receptors. Progesterone (PROG) is also a neurosteroid, and a progesterone receptor (PROG-R) has been identified in peripheral and central glial cells. At different places in the brain, neurosteroid concentrations vary according to environmental and behavioral circumstances, such as stress, sex recognition and aggressiveness. A physiological function of neurosteroids in the central nervous system is strongly suggested by the role of hippocampal PREGS with respect to memory, observed in aging rats. In the peripheral nervous system, a role for PROG synthesized in Schwann cells has been demonstrated in the repair of myelin after cryolesion of the sciatic nerve in vivo and in cultures of dorsal root ganglia neurites. It may be important to study the effect of abnormal neurosteroid concentrations/metabolism with a view to the possible treatment of functional and trophic disturbances of the nervous system.     

Development and regeneration of the nervous system: a role for neurosteroids

Several steroids, termed 'neurosteroids', are synthesized from cholesterol within both the central and peripheral nervous systems. These include pregnenolone and its sulfate ester, progesterone and its 5 alpha-reduced metabolites. Dehydroepiandrosterone, mainly in its sulfated form, also remains present in the brain long after removal of the steroidogenic endocrine glands. Its biosynthesis in brain remains an open possibility, but the pathways involved are unknown. Little information is available concerning the role of neurosteroids during the maturation of the nervous system, although they are already synthesized by glial cells and by some populations of neurons during embryonic life. Cell culture experiments suggest that neurosteroids may increase the survival and differentiation of both neurons and glial cells. In the adult nervous system, neurosteroids modulate neurotransmission by acting directly on the neuronal membrane and also produce structural changes in neurons and in astrocytes. Studies of neurosteroid levels are currently conducted to examine their possible role during aging. We have recently reported that progesterone, synthesized by Schwann cells, promotes the formation of new myelin sheaths after lesion of the mouse sciatic nerve. Thus, neurosteroids may also play an important role during regeneration of the nervous system.     

The GABAA receptor is expressed in human neurons derived from a teratocarcinoma cell line

NT2 cells, a human teratocarcinoma cell line, are shown to be differentiated in neuron-like cells (NT2-N cells) by treatment with retinoic acid. The present study identified the neurotransmitter receptors expressed in NT2-N cells using patch-clamp recording. Voltage-sensitive Na+ currents, which are specific for neurons, were observed in NT2-N cells but not in NT2 cells, suggesting that NT2-N cells actually function as neurons. Glutamate receptor agonists, N-methyl-D-aspartate (NMDA) and kainate, evoked whole-cell currents. In addition, gamma-aminobutyric acid (GABA) evoked currents and the currents were inhibited by the selective GABAA receptor antagonist, bicuculline. In outside-out patches, GABA elicited single channel currents with two classes of the slope conductance (26 and 50 pS). No current, however, was induced by ACh, serotonin, or dopamine NT2-N cells, thus, express at least two types of the major excitatory and inhibitory neurotransmitter receptor in the central nervous system, the glutamate and GAGAA receptors, suggesting that these receptors have a crucial role in neurotransmission from the earlier stage of the brain development.     

Spinal cord neuronal precursors generate multiple neuronal phenotypes in culture

Neuronal restricted precursors (NRPs) () can generate multiple neurotransmitter phenotypes during maturation in culture. Undifferentiated E-NCAM+ (embryonic neural cell adhesion molecule) immunoreactive NRPs are mitotically active and electrically immature, and they express only a subset of neuronal markers. Fully mature cells are postmitotic, process-bearing cells that are neurofilament-M and synaptophysin immunoreactive, and they synthesize and respond to different subsets of neurotransmitter molecules. Mature neurons that synthesize and respond to glycine, glutamate, GABA, dopamine, and acetylcholine can be identified by immunocytochemistry, RT-PCR, and calcium imaging in mass cultures. Individual NRPs also generate heterogeneous progeny as assessed by neurotransmitter response and synthesis, demonstrating the multipotent nature of the precursor cells. Differentiation can be modulated by sonic hedgehog (Shh) and bone morphogenetic protein (BMP)-2/4 molecules. Shh acts as a mitogen and inhibits differentiation (including cholinergic differentiation). BMP-2 and BMP-4, in contrast, inhibit cell division and promote differentiation (including cholinergic differentiation). Thus, a single neuronal precursor cell can differentiate into multiple classes of neurons, and this differentiation can be modulated by environmental signals.