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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Habituation of the lateral giant fibre escape response in the crayfish to repetitive tactile stimuli is believed to result from homosynaptic depression at the first synapse of the reflex, between tactile afferents and interneurones. Normally, habituation of escape responses to repeated innocuous stimuli is presumed to be adaptive. Experiments reported here were undertaken to determine whether habituation would occur under circumstances when it would presumably be maladaptive - in particular, when tactile receptors are stimulated by an animal's own tail-flip movements.2. Experiments were carried out on the crayfish isolated abdominal nerve cord, which contains the lateral giant reflex pathway.3. Compound e.p.s.p.s elicited in the lateral giant by electrical stimulation of tactile afferents decline by from 25 to 36% over a series of eleven trials at 1/5 sec (control series).4. To determine whether such a decline would occur when sensory afferents are stimulated during a ;tail-flip', stimuli were given as in the control series but each stimulus occurred 20 msec after direct electrical stimulation of a medial giant or lateral giant escape-command fibre at which time tail flexion movements of an intact animal would be in progress. Under these conditions% e.p.s.p. decline over 11 trials at 1/5 sec was only 16-45% of that occurring on the control series.5. This protective effect starts at about 10 msec after escape command neurone firing, is maximal at 20 msec, and thereafter declines, remaining weakly detectable at 100 msec. This time course is commensurate with that required for execution of a tail-flip movement. Thus, sensory afferent-to-lateral giant transmission is protected from depression if stimuli occur when a tail-flip movement is or should be occurring.6. Giant fibre spikes do not superimpose facilitation upon a depressed reflex pathway, nor accelerate rate of recovery from depression; rather, protection is attributable to actual prevention of development of the depressed state.7. Protection was also examined at the first synapse of the reflex, where the depression responsible for habituation is believed to occur, by recording intracellularly in the largest of the first-order interneurones (interneurone A) of the pathway. In absence of protection, ten stimuli presented at 1/4 sec caused a mean decline of 32% in the e.p.s.p. in interneurone A. When such stimuli followed directly evoked escape command neurone firing by 20 msec this decline was reduced by 59-100%.8. We suggest that protection serves to prevent crayfish from habituating to stimuli produced by their own tail-flip movements.
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PMID:Protection from habituation of the crayfish lateral giant fibre escape response. 20 Jul 34

1. Mechanism of protection from habituation of the lateral giant escape reflex of the crayfish was studied. Experiments were designed to determine whether presynaptic inhibition of primary afferents for the reflex occurs following escape command neurone firing, and if so, whether it could account for protection of the first synapse from depression. 2. Synaptic transmission between afferents and interneurone A of the escape reflex is strongly inhibited following giant fibre spikes. 3. Giant fibre firing results in post-synaptic inhibition of interneurone A. However, inhibition of afferent input to interneurone A consistently outlasts both i.p.s.p.s and post-synaptic conductance increases in the neurone; the inhibition, therefore, is probably not exclusively post-synaptic. 4. Giant fibre firing results in excitability changes in sensory afferent terminals as measured by the amplitude of antidromic compound action potentials to focal electrical stimuli applied in the region of afferent terminals in the last abdominal ganglion. The time course of this effect parallels those of protection and inhibition of the first synapse. 5. The magnitude and time course of protection and inhibition of transmission to interneurone A parallel each other closely. Both processes considerably outlast measurable signs of post-synaptic inhibition. 6. We conclude that following giant fibre activity the first synapse of the lateral giant reflex is presynaptically inhibited and the presynaptic inhibition is responsible for the protection effect described in the preceding paper.
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PMID:Presynaptic inhibition: the mechanism of protection from habituation of the crayfish lateral giant fibre escape response. 20 Jul 35

Decreasing the concentration of sodium in Meng's solution produced a non-parallel shift of the dose-response of acetylcholine on the intestine of the Giant African Snail Achatina fulica. This decrease in sodium decreases the sensitivity of the tissue to acetylcholine and sensitivity was not restored with several washings. The response to decrease calcium is very similar to that of sodium. In the case of potassium however 10% K+ produced less depression in sensitivity than 25% which even caused less depression of sensitivity compared with 50% potassium. The results show an abundance of spare receptors.
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PMID:Responses of the intestine of the giant African snail (Achatina fulica) to acetylcholine in Meng's solution with low sodium, potassium and calcium ions. 75 78

Polymyalgia rheumatica should be considered when a syndrome of constitutional symptoms, especially weight loss, low-grade fever, weakness, wasting proximal muscles, fatigue, malaise and depression, is seen in the elderly. Giant-cell arteritis plays a part later in the course. Thus the need for biopsy of a long segment of the temporal artery to help in determining diagnosis and therapy. An elevated erythrocyte sedimentation rate (ESR) is an important clue. The usual high value is about 80 mm/hour; if it is over 100 mm/hour, giant-cell arteritis should be suspected. Salicylates, indomethacin, phenylbutazone and hydroxychloroquine produce some clinical improvement but do not lower the high ESR; moreover, the patients are prone to experience relapses. Prednisone, however, not only produces clinical improvement but lowers the high ESR. Potassium p-aminobenzoate may be useful in maintaining the remission.
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PMID:Polymyalgia rheumatica. 124 88

The three-dimensional structure of the connective tissue core (CTC) of each type of lingual papillae of Mogella wogura wogura was studied by scanning electron microscopy after removal of the epithelial cell layer and compared with the results obtained from light microscopy as well as transmission electron microscopy. Filiform papillae are densely distributed on the dorsal surface of the anterior part of the tongue. They were conical in shape and their connective tissue cores (CTCs) resembled wooden spoons at the tip of the tongue, while they were flower-shaped (Lysichiton camtschatense) at the middle part of the tongue. Fungiform papillae which had a round depression on the top were distributed sporadically among the filiform papillae, and contained columnar CTC with several plane striations running longitudinally along the lateral surface. A pair of vallate papillae was located at the boundary between the anterior and posterior tongue. Their CTC were flower shaped closely resembling a carnation. Giant conical papillae occupied the posterior marginal region of the tongue. These papillae contained much smaller conical CTC similar to the outer form. Light and transmission electron microscopic observations of the dorsal lingual epithelium revealed three different regions: anterior region to the filiform papillae, posterior to the papillae and interpapillary region. In the intermediate layers between the germinal layer and the surface layer of the anterior region to the filiform papillae, a large number of keratohyaline granules was observed, but the cornified layer was obscured. In the posterior region, keratohyaline granules were fewer in number and the cornified layer was clear and thick. In the interpapillary region, keratohyaline granules were few and a thin cornified layer was recognized. At higher magnification, small sized keratohyaline granules contained a large number of free ribosomes, suggesting a close relationship between the two. Odland bodies were found only on the interpapillary region.
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PMID:[Fine morphological studies on the connective tissue core and the epithelial cells of the lingual papillae in Mogella wogura wogura]. 213 4

This discussion has illustrated the enormous variety found within the category of familial intrahepatic cholestasis. It has also demonstrated how much more there is to learn about these fascinating disorders, which may be examples of experiments in nature on bile formation. This analysis should be recognized to be the author's own, and there is much debate about this classification. For example, some workers in this field contend that North American Indian cholestasis is in reality Byler's syndrome. Such an identity seems unlikely, given the differences between the two syndromes (Table 2). This is a field that is changing rapidly. Recently, a new cholestatic syndrome, bearing some similarities to benign recurrent intrahepatic cholestasis, but dissimilar in several ways, has been reported. There is evidence that cholestasis of pregnancy may be inherited as an autosomal dominant, sex-limited trait. If further studies confirm a genetic etiology, this syndrome would be the most common form of familial intrahepatic cholestasis. The assessment of any individual case remains difficult, particularly early in the course. Table 2 can serve as a guide to the differential diagnosis of these conditions. When faced with a neonate with jaundice, all of the usual causes must be ruled out first. The pattern of bile acids in serum is useful for ruling out Zellweger's syndrome. A good family history and physical examination, particularly of the heart, are important. An ophthalmologic examination by a specialist, often under anesthesia, and a spine radiograph can be useful in confirming a diagnosis of Alagille's syndrome. A liver biopsy, carefully interpreted with input from the clinician, is useful in pointing toward one direction or another. Often a firm conclusion cannot be reached, or is reached prematurely, so the clinician would be advised to inform the parents of all diagnostic possibilities in order to avoid false hopes or unwarranted depression. The diagnostic pitfalls to be avoided in this evaluation are many. No histologic findings are clearly pathognomonic for one syndrome or another. Giant cell transformation and paucity of intrahepatic bile ducts may be found in several syndromes. Biliary atresia, or at least failure to demonstrate a patent biliary tree from the liver to the cystic duct, may be present in patients with Alagille's syndrome. In that syndrome, the eye findings, particularly the posterior embryotoxon, may not be appreciated except on extensive ophthalmologic testing, including gonioscopy. Butterfly vertebrae may not be visible at birth and may be no longer evident in adulthood.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Familial intrahepatic cholestatic syndromes. 330 44

A personal series of 256 cases of acromegaly/gigantism seen over a 20-year period from 1963 is described. The insidious nature of the condition resulted in delay in diagnosis which was often made by a doctor when seeing the patient for an unrelated problem. Other features which commonly led to the diagnosis being made were headache, change in appearance, carpal tunnel syndrome, amenorrhoea and diabetes. The Hardy system for grading the radiological appearance of the pituitary tumour was used. Widely invasive tumours were not common but tended to occur in patients with younger age of onset and high GH levels. The occurrence of various symptoms and clinical features was noted and the changes resulting from reducing the GH level to normal. The incidence of hypertension, but not of coronary artery disease, is increased and the blood pressure may be reduced following successful treatment. The effects on the upper and lower respiratory tract are reported as well as sleep apnoea and problems associated with anaesthesia. Skin manifestations included sweating, pigmented skin tags, acanthosis nigricans and cutis verticis gyrata. In the skeletal system the incidence of kyphoscoliosis and osteoarthritis especially of the hip is reported: the question of hip replacement is discussed. Diabetes mellitus disappeared in most cases if the acromegaly was cured. In men but not in women the incidence of colloid nodular goitre was increased as was hyperthyroidism in middle-aged women. In two patients a parathyroid adenoma was present: hypercalcaemia was present in five additional patients, but the cause was not determined. The common occurrence of amenorrhoea in the younger women was noted, it was not always associated with hyperprolactinaemia, and often responded to successful treatment of the acromegaly. The association of acromegaly with hirsutism and galactorrhoea is confirmed. The incidence of impotence and loss of libid in the men is discussed: in a proportion of those in whom the acromegaly was cured, potency returned, but in a number depression occurred and what was believed to be psychogenic impotence persisted. Hyperprolactinaemia was found in 49 out of 151 patients with active acromegaly in whom the prolactin level was measured. Previous reports have indicated a doubling of death rates in acromegalics. In this series there were 47 deaths observed compared to 37.2 expected. The increased death rate was in women of all ages and in men under the age of 55, The increased deaths in the women were from cardiovascular and cerebrovascular causes and from breast cancer.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Acromegaly. 330 90

The effects of toxic phospholipases A2 ( fraxtions "j", "k1" and "k2") isolated from the venom of Vipera ammodytes were studied on the chick biventer cervicis muscle and the mouse phrenic nerve-diaphragm preparations. In the chick muscle, all of these PLA2s caused neuromuscular (N-M) blockade without producing contracture or affecting the response of the muscle to acetylcholine. In the mouse diaphragm, these PLA2s inhibited completely the indirectly elicited contraction without affecting that evoked directly. The order of their N-M blocking potency is "k2" greater than "k1" greater than or equal to "j". In a low Ca2+ (0.5 mM) medium, they produced a triphasic change in the indirectly elicited contractions: an initial inhibition followed by an enhancement and then a progressive depression leading to complete N-M blockade. The frequency of miniature endplate potentials (m.e.p.p.s) in the mouse diaphragm first increased 2-3 fold and then gradually decreased after "k2" treatment, while the amplitude of m.e.p.p.s did not decrease even after the evoked release of transmitter failed. Giant potentials and bursts of m.e.p.p.s were frequently observed. The quantal content of e.p.p.s was first increased and then decreased gradually. The resting membrane potential was only slightly reduced at 30 micrograms per ml. The ultrastructure of motor nerve terminals in the "k2"-intoxicated mouse diaphragm showed an increase in omega-shaped indentation in the axolemma. The mitochondria in the nerve terminal were swollen and vacuolized. No structural changes were found in the muscle fibers, fibrocytes and myelinated axons in the diaphragm. It is concluded that the toxic PLA2s from Vipera ammodytes venom produce a N-M blockade by acting selectively on the presynaptic site.
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PMID:Mode of neuromuscular blocking action of toxic phospholipases A2 from Vipera ammodytes venom. 673 68

Mulinia lateralis, the dwarf surfclam, is a suitable model for bivalve genetics because it is hardy and has a short generation time. In this study, gynogenetic and triploid M. lateralis were successfully induced. For gynogenesis, eggs were fertilized with sperm irradiated with ultraviolet light and subsequently treated with cytochalasin B to block the release of the second polar body (PB2). Triploidy was induced by blocking PB2 in normally fertilized eggs. The survival of gynogenetic diploids was very low, only 0.7% to 8 days post-fertilization (PF), compared with 15.2% in the triploid groups and 27.5% in the normal diploid control. Larvae in all groups metamorphosed at 8-10 days PF, and there was no significant post-larval mortality. At sexual maturation (2-3 months PF), all gynogenetic diploids were female, and there was no significant difference (P > 0.05) in sex ratio between diploids and triploids. These results suggested that the dwarf surfclam may have an XX-female, XY-male sex determination with Y-domination. Compared with diploids, triploids had a relative fecundity of 59% for females and 80% for males. Eggs produced by triploid females were 53% larger (P < 0.001) in volume than those from diploid females. In both length and weight measurements at three months PF, the gynogenetic diploids were not significantly (P > 0.33) different from normal diploid females, suggesting that inbreeding depression was minimal in meiosis II gynogens. Triploid clams were significantly larger (P < 0.001) than normal diploids. We hypothesize that the increased body-size in triploids was caused by a polyploid gigantism due to the increased cell volume and a lack of cell-number compensation.
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PMID:Sex determination and polyploid gigantism in the dwarf surfclam (Mulinia lateralis Say). 789 1

Whole cell patch-clamp recording and intracellular staining with biocytin allowed the morphological and electrophysiological characterization of "giant" cells, studied in stratum (st.) radiatum of the CA3 region in 17- to 21-day-old rat hippocampal slices. These neurons had extensive dendritic arborization, a triangular soma, and a bipolar vertical orientation with axons directed to the pyramidal layer or extended into the st. oriens. Giant cells had significantly higher input resistance and shorter action potentials compared with CA3 pyramidal cells. Evoked action potentials were typically followed by an afterdepolarizing potential (ADP). During depolarizing current injection, most (80%) of recorded giant cells displayed a regular firing pattern (maximum steady-state firing rate, approximately 30 Hz) characterized by a modest early accommodation, whereas irregular firing was observed in the remaining 20% of giant cells. Hyperpolarizing current pulses induced a slow inward rectification of the electrotonic voltage responses, blocked by 2 mM external Cs(+). N-methyl-D-aspartate (NMDA) and non-NMDA-mediated excitatory postsynaptic currents (EPSCs) measured under voltage clamp were distinguished on the basis of their voltage dependence and sensitivity to specific NMDA and non-NMDA glutamate receptor blockers. Non-NMDA EPSCs possessed a linear current-voltage relationship. EPSCs elicited by st. lucidum stimulation were reversibly reduced (mean, 23%) by the group II metabotropic glutamate receptor agonist (2S, 1'R, 2'R, 3'R)-2-(2,3-dicarboxyl-cyclopropyl)-glycine (DCG-IV, 1 microM). GABA(A)-mediated postsynaptic currents were subject to paired-pulse depression that was inhibited by the GABA(B) antagonist CGP 55845A (5 microM). We conclude that CA3 giant cells represent a particular class of hippocampal neuron located in st. radiatum that shares only some morphological and physiological properties with principal cells.
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PMID:Electrophysiological characterization of "giant" cells in stratum radiatum of the CA3 hippocampal region. 1135 16


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