The innervation of the closer muscle of the mesothoracic spiracle of the locust.

The closer muscle of the mesothoracic spiracle of the locust, Schistocerca gregaria is innervated by two excitatory motoneurones and also by processes of a peripherally located neurosecretory cell. Within the muscle, ultrastructural studies show the presence of two types of excitatory nerve terminal which differ in the content of dense cored vesicles and in their distribution. The ventral segment of the muscle is innervated predominantly by terminals with small clear vesicles and only an occasional dense-cored vesicle. The central part of the muscle is innervated predominantly by terminals with small clear vesicles and larger numbers of dense-cored vesicles. The dorsal segment of the muscle is innervated exclusively by a neurosecretory type innervation. The small neurohaemal organ of the median nerve close to the spiracle muscle is immunoreactive to an antibody raised against bovine pancreatic polypeptide but no immunoreactive processes enter the muscle itself. The muscle possesses specific octopaminergic receptors that increase cyclic AMP levels and the possibility that the neurosecretory input to the muscle is provided by either a central or peripheral octopamine containing neurone is discussed.     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

Control of the circadian rhythm of the body temperature in the rat

The circadian rhythm of the rat body temperature is abolished in rats kept either in constant dark or light or blinded. The suppressive effects act most likely via the retinas. The rhythm can be inverted by reversal of the lighting regimen and it is unaffected by pinealectomy. Most likely the circadian rhythm is not related to changes in patterns of motor activity.     

Anatomy of the arteries of the head in the domestic fowl

The anatomy of the cephalic arterial system in the fowl was studied in 24 specimens by means of latex-injected preparations and by dissection. Branches of the external carotid artery supply the extracranial regions. The vertebral arteries unite with the occipitals and have no major communications with the encephalic system. Blood can reach the brain directly from the internal carotid artery and indirectly by way of the extensive cerebral-extracranial anastomoses; especially prominent are those to the palatine and sphenomaxillary arteries from the maxillary and facial branches of the external carotid artery. A large external ophthalmic artery supplies the temporal rete and eye musculature, and an internal ophthalmic artery links the rete and the cerebral vessels. The circle of Willis is incomplete both anteriorly and posteriorly; the anterior cerebral arteries do not unite and the basilar artery is generally asymmetrical in origin. The basilar artery tapers caudally and is continued as the ventral spinal artery.     

Characteristics of the effect of cestodes parasitizing the fish intestine on the activity of the host proteinases

The activity and spectrum of proteinases in the intestines of host fishes change upon infestation with cestodes. Serine proteinases are found to make a greater contribution to the total proteolytic activity. The reduction of proteolytic activity is associated with adsorption of the enzymes of the host on the surface of cestodes, and the increase in the activity is caused by the injury of the intestinal mucosa by the attachment apparatuses of cestodes. The inhibition of proteainase activity indicates the possible participation of microbiota enzymes in protein hydrolyses.     

Effect of hyperthermia on the polypeptide composition of the nuclear matrix of the rat liver

The increase in rat body temperature by 2-3 degrees as a result of overheating (45 degrees C, 22% humidity) over 90 and 120 min is accompanied by changes in the rate of labeled precursors incorporation into rat liver protein fractions. The incorporation of labeled amino acids into liver nuclear matrix proteins within the first 90 min of overheating is somewhat decreased, whereas 120 min thereafter it exceeds by 30% the corresponding values in control animals kept at room temperature. The polypeptide pattern of the nuclear matrix in hyperthermia is characterized by an increased relative content of polypeptide components around Mr 100, 55, 40 and 30 kDa against a decreased level of several polypeptides as compared to the control.     

Electron microscopical study on the development of the nerve supply of the pituitary pars intermedia of the mouse

Summary The development of the nerve supply of the pituitary pars intermedia (PI) of C3H mice was studied by electron microscopy. Nerve fibres and terminal structures, most probably adrenergic, first appear in the newborn. The adult innervation pattern is achieved by the end of the first postnatal week.In the adult animal two types of nerve terminals were distinguished; type A (peptidergic or neurosecretory) and type B (adrenergic). The peptidergic fibres were scarce and exhibited no synapse-like contacts. It is suggested that they are of secondary importance in a direct nervous hypothalamic control of PI function. Type B terminals were found throughout the PI. They formed synapse-like contacts with the glandular cells, indicating that the primary innervation is exerted by adrenergic neurons.An autonomous differentiation of the glandular cells and in the adult a combined direct nervous and neurohumoral control of PI function is suggested.This investigation was supported by grant No B 2180-026 from the Swedish Natural Science Research Council. The skilful technical assistance of Mrs Ulla Wennerberg is gratefully acknowledged     

Functional morphology of the subgenual organ of the carpenter ant

Using light microscopy, confocal microscopy, electron microscopy and histochemistry, the subgenual organ (SGO) of an ant, Camponutas ligniperda, is investigated. Sensory units and attachment cells together enclose a large extracellular cavity, which is filled by acid mucopolysaccharides, as revealed by staining with ruthenium red. Due to this cavity, the whole SGO has the shape of a deformed sphere and the scolopidia exhibit a distribution of angles between 0 degrees and 60 degrees with the tibial long axis (as is shown by phalloidin-rhodamin staining of the actin filaments of the scolopale, viewed in situ by laser scanning confocal microscopy). The subgenual organ is innervated by a branch of the tibial nerve, which splits within or shortly distal to the femur-tibia joint. The other features of the SGO of Camponotus ligniperda are similar as in other insects: the SGO of Camponotus ligniperda contains about 35 scolopidial sensilla; it is fixed to the subgenual nerve on its proximal end, by its attachment cells to the opposite part of the cuticle; the fixation by the attachment cells is accomplished by a vast quantity of cytoplasmic microtubules; the construction of the sensory units is the same as in other mononematic scolopidial organs. The role of the extracellular lumen inside the organ and the special shape of the SGO of Camponotus ligniperda in mechanical transmission is discussed.     

A comparison of the properties of the pyruvate kinases of the fat body and flight muscle of the adult male desert locust

1. The pyruvate kinases of the desert locust fat body and flight muscle were partially purified by ammonium sulphate fractionation. 2. The fat-body enzyme is allosterically activated by very low (1mum) concentrations of fructose 1,6-diphosphate, whereas the flight-muscle enzyme is unaffected by this metabolite at physiological pH. 3. Flight-muscle pyruvate kinase is activated by preincubation at 25 degrees for 5min., whereas the fat-body enzyme is unaffected by such treatment. 4. Both enzymes require 1-2mm-ADP for maximal activity and are inhibited at higher concentrations. With the fat-body enzyme inhibition by ADP is prevented by the presence of fructose 1,6-diphosphate. 5. Both enzymes are inhibited by ATP, half-maximal inhibition occurring at about 5mm-ATP. With the fat-body enzyme ATP inhibition can be reversed by fructose 1,6-diphosphate. 6. The fat-body enzyme exhibits maximal activity at about pH7.2 and the activity decreases rapidly above this pH. This inactivation at high pH is not observed in the presence of fructose 1,6-diphosphate, i.e. maximum stimulating effects of fructose 1,6-diphosphate are observed at high pH. The flight-muscle enzyme exhibits two optima, one at about pH7.2 as with the fat-body enzyme and the other at about pH8.5. Stimulation of the enzyme activity by fructose 1,6-diphosphate was observed at pH8.5 and above.     

Principles of the structuro-functional organization of the hemomicrocirculatory bed of the intramural nervous plexuses of organs of the gastrointestinal tract of mammals

The work deals with one of the least elaborated aspects on the system of microcirculation and is performed, taking into account the functions of histo-hematic and intertissue barriers. For this certain new original investigation methods have been developed, adequate to the problems discussed. The module principle of organization with a distinct functional specialization of the ganglionar and truncal vascular micromodules has been stated. The working principle of each module is based on functional interaction of the intra- and extraneural capillary systems; this is ensured by mechanisms of the blood stream redistribution: by arteriolar, precapillary and prevenular sphincters and by pathways of the shunt blood stream. A high stability of the blood stream in the vascular constructions studied is explained as a possibility of counterstream gas exchange between the arterial and venous blood in the truncal vascular micromodule.     

Characterization of the process for the biosynthesis of the actaplanin complex by Actinoplanes missouriensis

The production of the antibiotic actaplanin by Actinoplanes missouriensis was characterized in a high yielding process. The data generated, indicate that the antibiotic is synthesized during a period of declining cell mass as estimated by dry weight and viability. Further study demonstrated that the producing culture binds actaplanin and is inhibited by the antibiotic in the soluble form.     

Stochastic simulation of the gas diffusion in the air phase of the human lung

The solution of the diffusion equation in the gas phase of the human lung is very difficult because of the structure of the bronchial tree. It is shown by means of physical arguments, how one can reduce the diffusion equation to a simple one-dimensional form. The solution is then obtained by a stochastic simulation, which is easily realized on a digital computer.     

Action of organophosphorus compounds on the cation-sensitive p-nitrophenyl phosphatase of membranes from the retinal nerve of the squid

The cation-sensitive p-nitrophenyl phosphatase of nerve membranes is inhibited by DFP and the non-phosphorylating analogue triisopropyl phosphate. The inhibition requires 5–20 mM concentrations and is partly irreversible. The inhibition is distinct from that produced by the non-ionic detergent lubrol. Under some conditions dithiothreitol can inhibit the enzyme activity; under other conditions it can protect it against inactivation. The extent of the inactivation by DFP and triisopropyl phosphate is reduced in the presence of dithiothreitol. It is suggested that the primary action of the organophosphorus compounds is to change the reactivity of membrane sulphydryl or disulphide groups. The relevance of these findings to the blocking of conduction in the axon are discussed.     

On the relation between extended forms of the sinusoidal perfusion and of the convection-dispersion models of hepatic elimination

Two models of hepatic elimination, the distributed sinusoidal perfusion model, and the convection-dispersion model, are extended and then compared for first order kinetics in the steady-state. The sinusoidal perfusion model is extended by the inclusion of intrahepatic sites of mixing between sinusoids. The degree of such mixing is estimated for taurocholate elimination by isolated perfused rat livers by a comparison of anatomical and kinetic estimates of uptake heterogeneity, using previously published data. The dispersion model is generalized by the inclusion of distributions of enzyme activity along the flow. Direct comparison of the two models in the limit in which the degree of dispersion is small, allows the flow-dependence of the dispersion coefficient to be determined, thereby greatly extending the explanatory power of the convection-dispersion model. Finally, the effect of intrahepatic mixing sites on uptake by Michaelis-Menten kinetics is quantified in terms of the distributed sinusoidal perfusion model, with results which may be applicable to capillary beds in general.     

The effects of adrenalectomy on the harderian gland of the Wistar albino rats

Harderian glands of the Wistar albino rats normal and adrenalectomized were investigated by light microscopy. In normal, these glands have a tubuloalveolar structure. The gland is located in the medio posterior aspect of the orbit. It is lobulated and appears homogeneous in colour and texture. Harderian gland consist of tubules with wide lumina lined by a single layer of columnar epithelial cells surrounded by myoepithelial cells within their basal lamina. It contains porphyrin pigment which is stored as solid intraluminal deposits. The glandular epithelium possesses two cell types, termed A and B. Type A cells are more numerous. The single excretory duct of the gland is directly continuous with endpieces at the hilus and opens nasally and ventrally to the third eyelid. The excretory duct is accompanied by many acini of small serous glands around it. The tubuloalveoli of the gland is not divided into lobules. There is no branched duct system within the gland. The secretion seems to be associated with porphyrins, is essentially released by exocytosis, but holocrine secretion also occurs. The single excretory duct is lined by a stratified epithelium. The gland is surrounded by a collagenous capsule. The adrenalectomy, caused degenerative changes in the glands. Epithelial height was lower than in normal gland epithelium. Most of the acini were completely disorganised. The acinar lumina were filled with porphyrin debris. The results suggest that rat harderian glands are sensitive to adrenal androgen changes in both male and female rats.     

Reversal of the effect of the allosteric ligands of dCMP-aminohydrolase and stabilization of the enzyme in the T form

The 5-mercury derivative of dCMP is a substrate of deoxycytidylate aminohydrolase in the presence of mercaptoethanol. With this substrate a reversal of the effect of the allosteric ligands of the enzyme is observed. dCTP, which is an allosteric activator for aminohydrolysis of dCMP, becomes an inhibitor for the mercury substrate, whilst dTTP, an allosteric inhibitor for dCMP, becomes an activator for the mercury substrate.This observation has been interpreted by assuming that dCMP-Hg-S-CH₂-CH₂-OH is a substrate of the T form of the enzyme. By reacting dCMP-aminohydrolase in the T form (in the presence of dTTP) with glutaraldehyde, an enzyme has been isolated that is no longer active with dCMP, while it is fully active with the mercurated analog. Gel electrophoresis demonstrated that glutaraldehyde does not produce intermolecular crosslinks, but fixes 95% of the enzyme in a stable hexameric form by intramolecular crosslinks. The data are explained by assuming that glutaraldehyde stabilizes the enzyme in the T conformation.     

The participation of phospholipids in the interaction of leucocidin and the cell membrane of the polymorphonuclear leucocyte

1. The interaction of the two components of leucocidin with various lipids has been studied by sedimentation, flotation, light-scattering and changes in the biological activity of leucocidin. 2. Phosphatidylserine, phosphatidylcholine, diphosphoinositide, triphosphoinositide and phosphatidic acid, but not phosphatidylethanolamine, lysophosphatidylcholine, cerebrosides, gangliosides or tristearin, induce aggregation of the F component of leucocidin. 3. The S component of leucocidin does not interact directly with these phospholipids, but interacts with the F component of leucocidin after its modification by lipids. 4. The increased sedimentation or light-scattering induced by low phospholipid concentrations is reversed at higher phospholipid concentrations. 6. The aggregates formed by phospholipids and leucocidin are due, not to adsorption of leucocidin alone, but also to the formation of leucocidin polymers. 7. It is concluded that the aggregation is due to the interaction of the F component with the fatty acid side chains in the lipid micelle. 8. The S component of leucocidin is inactivated by triphosphoinositide at physiological ionic strength; the F component of leucocidin is inactivated at low ionic strength by triphosphoinositide and remains inactive when the ionic strength is increased. 9. It is suggested that in the leucocyte cell membrane the S component of leucocidin interacts with the polar hydrophilic groups of triphosphoinositide and that the F component of leucocidin interacts with the hydrophobic parts of triphosphoinositide.     

The pathophysiology of multiple sclerosis: the mechanisms underlying the production of symptoms and the natural history of the disease

The pathophysiology of multiple sclerosis is reviewed, with emphasis on the axonal conduction properties underlying the production of symptoms, and the course of the disease. The major cause of the negative symptoms during relapses (e.g. paralysis, blindness and numbness) is conduction block, caused largely by demyelination and inflammation, and possibly by defects in synaptic transmission and putative circulating blocking factors. Recovery from symptoms during remissions is due mainly to the restoration of axonal function, either by remyelination, the resolution of inflammation, or the restoration of conduction to axons which persist in the demyelinated state. Conduction in the latter axons shows a number of deficits, particularly with regard to the conduction of trains of impulses and these contribute to weakness and sensory problems. The mechanisms underlying the sensitivity of symptoms to changes in body temperature (Uhthoff's phenomenon) are discussed. The origin of 'positive' symptoms, such as tingling sensations, are described, including the generation of ectopic trains and bursts of impulses, ephaptic interactions between axons and/or neurons, the triggering of additional, spurious impulses by the transmission of normal impulses, the mechanosensitivity of axons underlying movement-induced sensations (e.g. Lhermitte's phenomenon) and pain. The clinical course of the disease is discussed, together with its relationship to the evolution of lesions as revealed by magnetic resonance imaging and spectroscopy. The earliest detectable event in the development of most new lesions is a breakdown of the blood-brain barrier in association with inflammation. Inflammation resolves after approximately one month, at which time there is an improvement in the symptoms. Demyelination occurs during the inflammatory phase of the lesion. An important mechanism determining persistent neurological deficit is axonal degeneration, although persistent conduction block arising from the failure of repair mechanisms probably also contributes.     

A morphologic study of the ductus of the epididymis of Sus domesticus

The head, body, and tail regions of the epididymal duct (or caput, corpus, and cauda epididymis) in two healthy and sexually mature Sus domesticus males were examined by light microscopy and by scanning or transmission electron microscopy. The epididymal duct is lined with a pseudostratified epithelium with stereocilia and covered by a muscular-connective tissue sheath that is thickest in the tail region. Diameter of the epididymal duct and height of epididymal epithelium are maximal in the head region. Length of the sterocilia and spermatic density are higher in the head and body regions. Somatic cells are abundant in the tail region. The epididymal epithelium is made up of five cell types: basal cells, principal cells, clear cells, narrow cells, and basophilic cells. Abundant secretory units are observed in the supranuclear cytoplasm of columnar principal cells. Each mature secretory unit is constituted by electron-dense secretion granules covered by more than eight layers of cisternae of reticulum between which the mitochondria are intercalated. In the apical cytoplasm the isolated secretion granules become larger and less electron dense. The apical surface is covered by numerous sterocilia. Basal cells are pyramidal and less high than principal cells. The clear cells, arranged between the principal cells, are characterized by the presence of abundant vesicular elements and electron-lucid secretion granules, and by an apocrine secretory process. The narrow cells are characterized by their highly vacuolized cytoplasm. Intermediate cell typologies can be found among basal, principal, clear, and narrow cells, which could be four developmental stages of the same cell type. The basophilic cells are spheroidal and are found at different levels between the epithelial cells and in the connective tissue underlying the epithelium. © 1993 Wiley-Liss, Inc.     

Vascularization of the conducting system in the human heart

On 200 randomized specimens of the human heart, of either sex, from 20 to 80 years of age, we investigated the vascularization of the conducting system of the heart in relation to the type of coronary ramification, by the dissection, injection-corrosive, radiographic and coronarographic method. The symmetrical type of arterial vascularization was established in 24%, the right type in 63% and the left type in 13% of the cases investigated. The sinoatrial node is vascularized in 60% by the right and in 40% of the cases by the left coronary artery. The atrioventricular node and the stem of the atrioventricular bundle are vascularized by the right coronary artery in 85% of the cases investigated, in 13% by the left and in 2% by both arteries. The right fasciculus of the atrioventricular bundle is vascularized by the left artery, the left fasciculus by both arteries. The vascularization of the posterior strand in both ventricles is conformable to the type of arterial vascularization of the heart.