Specific Acetylcholinesterase Research Articles

Effects of Cholinergic Drugs on Longitudinal Muscle Contractions of Fasciola hepatica

Acetylcholine, cholinergic agonists and acetylcholinesterase inhibitors significantly decrease the amplitude and frequency of spontaneous longitudinal muscle contractions in Fasciola hepatica. In order of their effects on the inhibition of muscle contractions, the cholinergic agonists can be ranked as nicotine greater than carbachol greater than acetylcholine. High calcium ion concentration also causes a significant inhibition of contractions. Atropine, a cholinergic antagonist that acts on muscarinic receptors, significantly increases the amplitude and frequency of spontaneous contractions and completely reverses the effects of cholinomimetic drugs, including nicotine. In adult F. hepatica, the levels of acetylcholine and its precursor choline are 3.14 +/- 0.55 and 13.75 +/- 3.72 pmol/mg wet weight, respectively. The activities of choline acetyltransferase, specific acetylcholinesterase and the nonspecific cholinesterase are 1.25 +/- 0.19, 238.0 +/- 13.0, and 83.0 +/- 33.0 nmol/hr/mg protein, respectively.

Autonomic innervation of interstitial cells in the nasal respiratory mucosa.

We analyzed the microscopic innervations of the pars respiratoria of the nasal mucosa in humans, cats, and rabbits. To this end, the techniques of Jabonero, Champy-Maillet, and Koelle-Friedenwald were employed to detect specific acetylcholinesterase activity. The supremum colli ganglion was also removed from cats in order to observe any tissue changes produced. Using our histochemical techniques, we were able to demonstrate for the first time that Cajal's interstitial cells in the nasal mucosa are acetylcholinesterase-positive. These cells also appear to be totally integrated into the structure of the terminal vegetative neural formations. Additionally, the fibers surrounding these cells were found to show early degeneration after experimental cervical sympathectomies had been performed.

Mapping of cholinoceptive(nicotinoceptive) neurons in the lower brainstem: with special reference to the ventral surface of the medulla

The distribution of cholinoceptive neurons in the lower brainstem of the rat was investigated by means of a histochemical method for specific acetylcholinesterase. Nicotinoceptive neurons were characterized using an α-bungarotoxin-horseradish peroxidase conjugate for the detection of nicotinic acetylcholine receptors. For the first time a nearly complete mapping of the location of cholinoceptive (nicotinoceptive) neurons of the lower brainstem was achieved. Special attention was focused on the organization of the cholinoceptive neuronal matrix of the ventral surface of the medulla, where regulative centers for vasomotor and respiratory control are located.

Acetylcholinesterase from fetal bovine serum. Purification and characterization of soluble G4 enzyme.

Acetylcholinesterase (EC 3.1.1.7) from fetal bovine serum (FBS) was purified to electrophoretic homogeneity. The procedure involved procainamide affinity chromatography with native FBS, followed by chromatography on Sepharose 6B and DEAE-Sephadex. The acetylcholinesterase was purified approximately 44,000-fold, and 13 mg was obtained corresponding to an overall yield of about 45%. The purified acetylcholinesterase was stable at 4 degrees C for at least 8 weeks but was labile to freezing; however, in 50% glycerol the enzyme was stable at -20 degrees C for at least 12 weeks. FBS acetylcholinesterase exhibited typical substrate inhibition, had a Km of 120 microM, and a turnover number of 5300 s-1 with the substrate acetylthiocholine. The enzyme was highly sensitive to the specific acetylcholinesterase inhibitor 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one. FBS acetylcholinesterase was characterized as a G4 form of acetylcholinesterase and was distinguished from bovine erythrocyte acetylcholinesterase on the basis of lectin gel binding, [3H] Triton X-100 binding, amino acid composition, number of catalytic subunits/molecule, and hydrodynamic properties. FBS acetylcholinesterase had a Stokes radius of 76 A as judged by gel filtration, and from this a molecular weight of 340,000 daltons was calculated. The enzyme had a subunit weight of approximately 83,000 daltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; paraoxon titration indicated a relative active site mass of 75,000 daltons. The amino acid composition of FBS acetylcholinesterase was similar to the human erythrocyte acetylcholinesterase (Rosenberry, T. L., and Scoggin, D. M. (1984) J. Biol. Chem. 259, 5643-5652). A monoclonal antibody directed against human erythrocyte acetylcholinesterase, AE-2, (Fambrough, D. M., Engel, A. G., and Rosenberry, T. L. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 1078-1082) cross-reacted with FBS acetylcholinesterase.

Scanning electron microscopy and X-ray microprobe analysis in detection of acetylcholinesterase in cultured embryonal carcinoma cells.

Mouse F9 cells, induced by retinoic acid and dibutyryl cyclic adenosine monophosphate (cAMP) to differentiate into neural-type cells, were incubated for localization of specific acetylcholinesterase (AChE) activity according to the Karnovsky-Roots method where the final enzymatic reaction product is crystalline cupric ferrocyanide and cuprous thiocholine iodide. By scanning electron microscopy (SEM) neural-type cells with long processes were seen. Most of these cells exhibited crystalline precipitates on their surface that in microprobe analysis contained copper, iron, and sulfur. These elements were also detected in some of the neural-type cells that had no visible surface precipitates. Thus, the X-ray analysis also revealed intracellular enzymatic activity. Undifferentiated rounded cells, devoid of AChE activity at the light microscope level, did not show any surface precipitates by SEM and lacked copper, iron, and sulfur emission peaks in the elementary analysis. These results demonstrate that elementary analysis of cytochemical enzymatic reaction products by SEM can be used in identifying cells.

Localization of cholinesterase activity in the outer plexiform layer of the larval tiger salamander retina

Acetylcholinesterase activity, which may be indicative of cholinergic synapses, has been ultrastructurally localized in the outer plexiform layer of the larval tiger salamander retina using the cholinesterase staining method of Karnovsky and Roots. In the presence of the butyrylcholinesterase inhibitor, ethopropazine, precipitate is localized to discrete ‘stain laminae’ about 300 nm in their largest dimension and bounded by a 10 nm wide electron-lucent gap. Stain laminae are predominantly found adjacent to horizontal cell axon terminals which were identified by serial section analysis. Stain precipitate has not been found associated with horizontal cell dendrites and in only one case was a lamina found adjacent to a bipolar cell dendrite. Intracellular deposits of cholinesterase stain precipitate were also observed. In some cases, stain is found adjacent to synaptic ribbons in photoreceptor terminals. Likely artifacts appear to have been ruled out by control experiments in which retinas either were not treated with cholinesterase stain or were treated in the presence of the specific acetylcholinesterase inhibitor, BW284C51. Thus, the stain laminae probably result from specific, highly localized areas of acetylcholinesterase activity. The implications of the present study on current theories of cholinergic function in the vertebrate retina are discussed.

Acetylcholinesterase activity of Xenopus laevis oocytes

The cholinesterase activity of Xenopus laevis oocytes was assessed using [ 3H]acetylcholine in a simple radiometric procedure. The cholinesterase activity of mature (stage V–VI) oocytes was very sensitive to inhibition by the specific acetylcholinesterase inhibitor, BW284-C51, and relatively insensitive to an inhibitor of non-specific, or butyrylcholinesterase. The K m and v max of the acetylcholinesterase measured in homogenates of oocytes were 312 μM and 4.6 nmol-oocyte −1-h −1, respectively. Triton X-100 increased the enzyme activity of homogenates four- to five-fold while collagenase treatment displaced into the medium none of the acetylcholinesterase activity from either homogenates or intact oocytes. Cations were found generally to diminish the acetylcholinesterase activity of oocyte homogenates, and lanthanum ions inhibited acetylcholine hydrolysis with an IC 50 of 0.63 mM. Subcellular fractionation of oocytes revealed that the bulk of enzyme activity was associated with particulate fractions. Acetylcholinesterase activity was also detected on the surface, and in homogenates, of immature oocytes. Peak enzyme activity resided in stage IV oocytes. Eggs obtained from females induced to spawn were found to have acetylcholinesterase activity in homogenates but little or no hydrolytic activity was detected on the egg surface. These results provide a point of departure for further investigations of the functional significance of this enzyme in Xenopus oocytes.

Progressive partial lipodystrophy in association with intrauterine death and growth retardation

Atresia and fistula of the esophagus are among the most common congenital anomalies, but their prenatal diagnosis is only rarely achieved by ultrasonography, amniofetography or cu-fetoprotein (AFP) determination. Intra-amniotic injection of radiopaque dye into the amniotic cavity and radiologic imaging of the fetal gastrointestinal tract have been used most frequently in pregnancies with hydramnios and the sonographic finding of absent fluid in the gastrointestinal tract. It is known, however, that partial passage of the x-ray contrast medium into the fetal intestine in cases of esophageal atresia can occur, thus giving rise to a false negative diagnosis. A simple and reliable biochemical marker present in the amniotic fluid would be of great practical importance. Amniotic fluid acetylcholinesterase as a possible marker for the prenatal diagnosis of esophageal atresia was recently suggested by a case report of a pregnancy characterized by fetal esophageal atresia, polyhydramnios, ambiguous amniofetography, a normal amniotic fluid AFP concentration, and an elevated amniotic fluid acetylcholinesterase level.’ To test the reliability of this proposed marker we retrospectively examined samples of clear amniotic fluid obtained at second-trimester amniocenteses of three pregnancies, each of which proved to be complicated by upper gastrointestinal atresia. Two of these cases had a positive acetylcholinesterase band on gel electrophoresis and normal AFP concentrations. In one case of an esophageal atresia with tracheoesophageal fistula a normal AFP value and no specific acetylcholinesterase band was found on electrophoresis.

Control of Swimming in Cercariae of Proterometra macrostoma (Digenea)

A specific acetylcholinesterase (AChE) was localized histochemically in Proterometra macrostoma cercariae. This esterase activity was inhibited by eserine, but was resistant to tetraisopropyl pyrophosphoramide. A transverse band of intense AChE activity was observed in the posterior region of the tail. Suction electrode recordings from the tail showed that the action potentials associated with swimming activity were conducted from the transverse band region toward the anterior end of the tail. Removal of the body of the cercaria had no effect on the cyclical electrical activity. 5-Hydroxytryptamine had a strong excitatory effect on the electrical activity whereas acetylcholine and eserine were inhibitory. These observations suggested that swimming behavior was initiated in the transverse band of the tail and that the neuromuscular activity underlying this behavior may be modulated by acetylcholine. Swimming behavior of Proterometra macrostoma cercariae is characterized by alternating periods of swimming and sinking (Prior and Uglem, 1979). Aided by a pair of flat furcae, alternating lateral contractions of the tail pull the cercaria up through the water. A single, biphasic, action potential precedes each contraction of the tail. Following a burst of swimming the cercaria drifts passively downward until touching some object. Once it contacts something another sequence of swimming is initiated. Although the duration of a swimming period is quite regular, a burst of swimming can be initiated at any time during a period of sinking. The body of this large furcocystocercous cercaria is attached to the anterior end of the tail, and is usually withdrawn into the tail at the time of emergence from the snail. One of the most striking aspects of the electrical pattern underlying swimming activity is that the pattern continues unaltered after detachment of the body from the tail. Furthermore, the potentials are conducted from the posterior to the anterior end of the tail. These observations suggested that swimming activity is generated in the posterior region of the tail. We have localized a band of intense, acetylcholinesterase activity in the posterior region of the tail using the histochemical method of Gomori (1952). Our report describes the transverse band and also the effects of various drugs that suggest that the neuromuscular activity underlying swimming behavior may be modulated by acetylcholine. Received 14 October 1982; revised 28 December 1982; accepted 6 January 1983. MATERIALS AND METHODS Snails of the genus Goniobasis Lea infected with Proterometra macrostoma were collected from local, springfed streams and placed in shallow pans of well-aerated natural spring water. Cercariae emerged from the snails after several hours in the laboratory. Some snails were cracked open and the cercariae carefully teased from the tissues. The cercariae were transferred to artificial spring water (ASW; 0.5 mM NaCl, 0.05 mM KC1, 0.4 mM CaCl2, and 0.025 mM MgCl) and held for 2 hr at 25 C prior to use in experiments. Acetylcholinesterase (AChE) was localized histochemically according to the method of Gomori (1952). Worms were incubated (37 C) in the reaction medium for 3 to 6 hr. The reaction medium contained as substrate acetylthiocholine iodide (2 mg/ml; Sigma, St. Louis, Missouri), and in some cases cholinesterase inhibitors, 10-3 M eserine sulfate or 10-4 M tetraisopropyl pyrophosphoramide (isoOMPA; Sigma). The stained cercariae were dehydrated, cleared and prepared as whole mounts for photomicrography. The electrophysiological recordings were made by applying thin plastic tubing as suction electrodes to the tails of cercariae that had been pinned to the bottom of a recording chamber filled with ASW (18-22 C). The signals were amplified and recorded with a Grass P79 polygraph or kymograph camera. Drugs were applied to cercariae by replacing the ASW in the recording chamber (approximate volume = 2.0 ml) using a perfusion system. The effect of each drug on the swimming rhythm was based on observations of at least 25 bursts of swimming. Results are expressed as the x + SD. Differences were analyzed using the Student's t-test; a value of P < 0.05 was considered significant. Acetylcholine, 5-hydroxytryptamine (5-HT), carbamylcholine chloride (carbachol) and eserine sulfate were obtained from Sigma. All chemicals were reagent grade.

Reinnervation of Human Skin Grafts

The reinnervation of nine human skin grafts was investigated using histochemical thiocholine methods for the demonstration of cholinesterases. The regenerated cutaneous nerves showed both specific acetylcholinesterase and nonspecific cholinesterase reactions. In the youngest specimens, taken 3 weeks after the grafting, such regenerated nerves were seen both at the subdermal level under the graft and at the margins of the graft. These nerves seemed to orient toward the denervated graft area. The growing nerves were generally distributed in a random fashion. The reinnervation of some hair follicles, erector pili muscles, and sweat glands were observed in well-innervated full-thickness and thick partial-thickness skin grafts. It is suggested that this target-organ control of regenerating nerves occurs as a result of the action of chemotactic factors. A well-innervated graft bed seems to be important for optimum reinnervation of skin grafts. Fibrosis and scarring seem to hamper nerve regeneration.

Comparative localization of acetylcholinesterase and pseudocholinesterase during morphogenesis of the chicken brain.

The histochemical localization of specific acetylcholinesterase (AcChoEase) and nonspecific cholinesterase (BtChoEase) is described during the early morphogenesis of the whole chicken head with main emphasis on the visual system. It is found that: (i) Expression of AcChoEase is an early differentiation event in the entire brain. Its pattern of first appearance on the external part of the neuroepithelium correlates with the general spatio-temporal pattern of differentiation. AcChoEase thus represents an early differentiation marker. (ii) The late pattern of AcChoEase (at E18), reflecting at least partially the distribution of synaptic AcChoEase shows no direct correlation to the distributions found at early stages when synapses are not yet formed. This argues for a nonsynaptic function of the early appearing AcChoEase. (iii) BtChoEase in early nervous tissue is diffusely localized on the ventricular side of the neural tube. At later stages it becomes concentrated on the ependymal layer as well as along fibers reaching from this inner layer outwards. Minor activities appear in specific external layers of tectum and retina. (iv) During the course of differentiation the enzymes express pronounced graded distributions within the areas where they are detectable. (v) Mesenchymal and epidermal BtChoEase is abundant in the entire head. Prominent amounts of activity are expressed on the rostral epidermis, along the eye cup next to the sclera, and on the rostro-dorsal surrounding of the optic nerves. The results are discussed in the light of possible morphogenetic functions of these enzymes.

Alphafetoprotein (AFP), concanavalin A non-reactive AFP and specific acetylcholinesterase in amniotic fluid from pathological pregnancies. Predictive values for open spina bifida

Alphafetoprotein (AFP) and concanavalin A non-reactive alphafetoprotein determination and the acetylcholinesterase (AchE) qualitative test have been performed on amniotic fluid samples from 33 normal pregnancies, 44 pregnancies with fetal malformations and 8 normal pregnancies with elevated amniotic fluid alphafetoprotein (3 false positive AFP results, 5 contaminations with fetal blood). The validities of these three tests in detecting abnormal pregnancies are compared. The usefulness of the existing complementary tests in the detection of neural tube defects in a low neural tube defect incidence area is discussed. Risk figures for open spina bifida according to the prior risk situation and the results of maternal serum AFP, amniotic fluid AFP, AchE qualitative test and ultrasound examination have been calculated.

Biphasic effect of eserine and other acetylcholinesterase inhibitors on the nicotinic response to acetylcholine in cultured adrenal chromaffin cells.

Abstract: A pharmacological study was made of the effects of various anticholinesterases (anti‐ChEs) on the release of [3H]noradrenaline ([3H]NA) evoked by acetylcholine (ACh), nicotine, 56 mM K+, and veratridine from bovine adrenal chromaffin cells in culture. The anti‐ChEs chosen were eserine (an inhibitor of both acetylcholinesterase and pseudocholinesterase), 1,5‐bis‐(4‐allyldimethylammoniumphenyl)pentan‐3‐one dibromide (BW284C51) (a specific acetylcholinesterase (AChE) inhibitor), and tetraisopropylprophos‐phoramide (iso‐OMPA) (a specific pseudocholinesterase inhibitor). Acetylcholinesterase (AChE) activity increased in the cells with time in culture beginning at day 4 and reaching a plateau at day 10. In 9–11‐day cultures, both eserine and BW284C51 acted biphasically to increase ACh‐induced [3H]NA release from the cells at concentrations of 10−6M or less whereas higher concentrations reduced or abolished the ACh‐induced release. However, in earlier cultures (days 3–5), when AChE activity of the cells was low, both eserine and BW284C51 produced only a monophasic dose‐dependent inhibition of ACh‐evoked [3H]NA release at high concentrations. When the cells were stimulated with nicotine, an agonist not metabolized by cholinesterase a similar monophasic inhibitory response on the [3H]NA release was elicited by eserine and BW284C51, regardless of the age of the cultured cells. When 56 mM K+ or veratridine was used to depolarize the cells, neither eserine nor BW284C51 affected the [3H]NA release from the cells. Unlike eserine and BW284C51, iso‐OMPA did not enhance ACh‐evoked release in older cultures and at high concentrations (&gt; 10 4M) it produced an inhibition of the [3H]NA release evoked by ACh, nicotine, 56 mM K+, and veratridine. The present results suggest that the stimulatory effect on ACh response by low concentrations of eserine and BW284C51 can be attributed to the protection of ACh against enzymatic hydrolysis, whereas the inhibitory effects produced by higher concentrations of eserine and BW284C51 are thought to be due to an interaction with the nicotinic acetylcholine receptor‐ionophore complex.

Changes in the intestinal enzyme activity of lambs during chronic infection with Trichostrongylus vitrinus

The pathology and enzymology of the intestinal mucosae of lambs dosed daily with 2500 Trichostrongylus vitrinus larvae and killed at five, nine or 14 weeks were compared with worm-free animals. The proximal small intestines of the infected lambs exhibited extensive mucosal damage at five and nine weeks, but only isolated lesions were found at 14 weeks. Activities of the brush border enzymes alkaline phosphatase, leucine amino-peptidase, maltase and glycyl-L-leucine dipeptidase were all significantly depleted during infection, although the magnitude, time of onset and duration of the individual enzyme responses varied. Mucosal activities of the pancreatic enzymes, trypsin and to a lesser extent chymotrypsin were also markedly decreased particularly during the first nine weeks of infection. Specific acetylcholinesterase activity was significantly increased throughout the study, maximal levels being observed at five weeks. In contrast 'pseudo'-cholinesterase levels were consistently within the control range. During the early stages of infection (five weeks) glutamine-oxaloacetate transaminase activity was significantly decreased, while aldolase and creatine phosphokinase levels were significantly elevated. At nine weeks low glutamine-oxaloacetate transaminase activities were again detected and lactate dehydrogenase activity was also markedly reduced. At 14 weeks the mean activities of all four enzymes were within the normal range as were superoxide dismutase levels throughout. Significant correlations were found between alkaline phosphatase, trypsin, chymotrypsin, aldolase and glutamine-oxaloacetate transaminase activities and the degree of mucosal damage within the individual lambs.

Surface AChE in the chick ciliary ganglion neurons: Ultrastructural localization and possible relations to α-bungarotoxin receptors

The localization of acetylcholinesterase activity in the chick ciliary ganglion was investigated by ultrastructural cytochemistry. Both ganglionic cell populations, i.e. the ciliary and the choroid neurons, showed similar distribution patterns of the enzymic activity in the cytoplasm as well as at the neuronal surface. As indicated by specific inhibition tests, the whole enzymic activity was attributable to specific acetylcholinesterase. While the endocellular activity was mainly localized in the rough endoplasmic reticulum, the surface activity occurred at postsynaptic level and at extrasynaptic areas, where the neuronal membrane comes into contact with the plasma membrane of the satellite cell (boundary neuron-satellite cell). Enzymic activity also uniformly occurred at the surface of preganglionic nerve terminals. The surface localization of specific acetylcholinesterase recalls that recently described for α-bungarotoxin receptors, which suggests that acetylcholinesterase and α-bungarotoxin receptors can be distributed together, not only at postsynaptic level but also in extrasynaptic neuronal areas and at presynaptic level. The possibility that α-bungarotoxin receptors and acetylcholinesterase form a ·receptive’ system not engaged in ganglionic transmission and not exclusively confined to postsynaptic level is discussed in relation to the electrophysiological data existing in literature.

Quantitative and qualitative assay of amniotic-fluid acetylcholinesterase in the prenatal diagnosis of neural tube defects

In 110 amniotic fluids the specific acetylcholinesterase was determined quantitatively and qualitatively. In the quantitative assay there were a considerable number of false positives and false negatives, although the mean value of the normal controls differed significantly from that of neural tube defect pregnancies. By the electrophoretic separation of acetylcholinesterase, however, all fluid samples with borderline alpha-fetoprotein levels or fetal blood contamination could be correctly classified. With the exception of one skin-covered spina bifida all neural tube defects in the second trimester could be identified by this method. The second fast-moving band characteristic of the specific acetylcholinesterase was also present in abdominal wall defects and intrauterine death.

Autonomic innervation of rabbit urinary bladder following estrogen administration

The effects of estrogen administration on the autonomic innervation of the rabbit urinary bladder were studied. Immature female white rabbits were injected twice daily with estrogen (150 μg./Kg.) for four consecutive days. Control animals received injections of vehicle alone. The adrenergic innervation was identified using the glyoxalic acid method of catecholamine histofluorescence. The cholinergic innervation was visualized utilizing specific acetylcholinesterase staining. Additionally, the effect of estrogen administration on the response of smooth muscle strips of urinary bladder to specific autonomic agonists was determined. Estrogen administration induced a moderate increase in the adrenergic innervation of the rabbit bladder detrusor, whereas no change could be observed in the cholinergic innervation. It should be noted, however, that whereas the adrenergic innervation in the bladder of the control animal was sparse, the cholinergic innervation in the bladder body was quite dense. Estrogen induced a marked increase in the response to alpha -adrenergic (methoxamine) and muscarinic cholinergic (bethanechol) agonists. No alterations were noted in the response to beta-adrenergic agonists (isoproterenol). These findings indicate that the urinary bladder responds as a target organ of estrogen-induced alterations in autonomic innervation.

Gel electrophoresis of amniotic fluid acetylcholinesterase as an aid to the prenatal diagnosis of fetal defects

The presence or absence of a specific acetylcholinesterase (AChE) band was determined by polyacrylamide gel electrophoresis on 272 second trimester amniotic fluid samples. The AChE band was absent from 176 normal samples, including seven which had been scored as false positives by alphafetoprotein (AFP) assay. It was present in all 30 samples from open neural tube defects, of which four had been scored as false negatives by AFP assay. In the remaining 66 pregnancies with abnormal outcome, an AChE band was in general present when AFP was raised and absent when it was normal. However, all six cases of congenital nephrosis had raised AFP and no AChE band, while two of 30 pregnancies ending in spontaneous abortion had an AChE band and normal AFP. These results suggest that AChE electrophoresis is a valuable confirmatory technique for the early prenatal diagnosis of fetal abnormalities.

Collagenase-releasable and -resistant cholinesterases in normal and dystrophic muscles.

The release of acetylcholinesterase activity by collagenase from the particulate fraction of mouse muscle homogenate into the soluble fraction was dependent on the time of incubation of muscle homogenate with collagenase. The collagenase-stimulated release of acetylcholinesterase was inhibited by 1,10-phenanthroline, an inhibitor of collagenase. Differential effects of inhibitors of specific acetylcholinesterase and nonspecific cholinesterase were observed in both collagenase extract and collagenase-resistant fraction derived from homogenate of muscle of normal and dystrophic mice. The collagenase extract of dystrophic muscle contained distinctly lower activity of acetylcholinesterase than that of normal muscle, while both collagenase extract and collagenase-resistant fraction of dystrophic muscle showed much higher activity of butyrylcholinesterase activity than those from normal muscle.

Amniotic fluid acetylcholinesterase and prenatal diagnosis.

Raised specific acetylcholinesterase (AChE) activity in amniotic fluid was consistently found to be associated with fetal intrauterine death and neural tube defects, but in just under half of the samples from pregnancies with spina bifida, the increase was marginal. Elevated AChE levels were occasionally found in fluid samples contaminated by maternal blood, and in nearly half of the samples which were a brown or yellow-brown colour but where there was a normal fetus. Nine fluids, five of which were contaminated with fetal blood, had a false positive result on alpha-fetoprotein (AFP) assay (elevated AFP levels and a normal fetus), but showed normal AChE activities. It is suggested that AChE estimation might be useful in prenatal diagnosis as a second test for those fluids which have an elevated AFP level.