bluuebunny/crossref_metadata_2025_split huggingface dataset:
DISTRIBUTION AND PROPERTIES OF MUSCLE SPINDLES IN THE CAUDAL SEGMENTAL MUSCLES OF THE RAT TOGETHER WITH SOME COMPARISONS WITH HIND LIMB MUSCLE SPINDLES
Authors: Andrew B. L. , Leslie G. C. , Thompson J. 
Published: December 2014

The afferent activity in sensory nerve fibres was recorded when lateral segmental muscles of the rat tail were stimulated mechanically. The muscles were then examined histologically and the muscle spindle content established. The distribution of spindles along the tail length and their innervation pattern was obtained. The overall ratio of primary to secondary endings was approximately two to one. Most single spindles (67% of sample) were intermediate; parallel (dual) spindles (29% of sample) usually combined a simple with an intermediate spindle; complex spindles were rare.The maximum muscle extension during tail‐bending movements was a submaximal stimulus to tail spindles; there was no resting discharge in the straight tail position in the absence of fusimotor stimulation.The spindle endings were compared with those in rat hind limb muscles in terms of dynamic index, vibration sensitivity, spindle complexity and conduction velocity of afferent fibres. In all four aspects the tail values were more restricted in range; all caudal spindle endings had lower dynamic indices, lower vibration sensitivity and lower afferent conduction velocities than those found in primary endings in the three hind limb muscles examined (peroneus longus, peroneus brevis and gastrocnemius lateralis). A positive correlation between spindle afferent conduction velocity and vibration sensitivity of caudal spindle endings was recognized, and the possible role of afferent fibre size in determining spindle properties discussed.
THE MITOSIS OF SHEEP BLOOD MONOCYTES IN TISSUE CULTURE
Authors: Greenwood B. 
Published: December 2014

A technique is described by which sheep blood monocytes have been collected in tissue culture chambers and maintained in frequent changes of 100% autologous blood plasma. Such cells grow in size, and, having assumed a large macrophage form, they divide by mitosis. The cultures have been observed daily and their mitotic indices determined by counting 2,000 cells. These indices peak about the eighth day in culture. Mitotic activity then diminishes and usually dies out. The products of mitosis are two daughter cells which have macrophage size and morphology, and never at any time resemble fresh blood monocytes. These events have been confirmed by continuous recording with time‐lapse cine‐photomicrography.The work demonstrates the proliferative capacity of the mammalian blood monocyte. The cell collection technique and the observation and continuous recording of living cultures have been directed at refuting any possible criticism that mitoses were occurring in contaminating fibroblasts.
THE EVALUATION OF A MACHINE FOR INTRODUCING TOBACCO SMOKE INTO THE LUNGS OF ANAESTHETIZED ANIMALS DURING SPONTANEOUS RESPIRATION
Authors: Armitage A. K. , Houseman T. H. , Turner D. M. , Wilson D. A. 
Published: December 2014

1. A new smoking machine is described for introducing a measured sample of a 25 ml. puff of tobacco smoke into the lungs of anaesthetized cats, or other experimental animals with similar respiratory characteristics.2. Important features of the machine are that undiluted smoke is taken directly into the lungs during essentially normal respiration and that the dose administered can be monitored.3. The efficiency of the machine in administering nicotine and carbon monoxide has been measured. The presentation of smoke to the animals' lungs is considered to resemble the way in which the human cigarette smoker ‘inhales’ smoke into his lungs.
ADENOSINE TRIPHOSPHATASE LOCATED ON UNSTIMULATED HUMAN SMALL LYMPHOCYTE CELL MEMBRANES
Authors: Coulson A. S. , Zeitman V. H. , Cohn R. B. , Dong E. , Griepp R. B. , Stinson E. B. , Shumway N. E. 
Published: December 2014

This study was undertaken to localize the enzyme sodium‐potassium dependent adenosine triphosphatase in unstimulated human small lymphocytes using the histochemical technique of McClurkin [1964]. The substrate adenosine 5' triphosphate is hydrolyzed by the ATPase resulting in a lead phosphate precipitate at the site of enzyme action, subsequently visualized as lead sulphide.The enzyme was demonstrated in three different patterns, and for each donor the pattern was constant both on all four of the test slides, and on different occasions. The patterns observed were: clusters of granules related to the cell membrane; positive staining localized to portions of the cell membrane, and, less commonly, the whole cell circumference. The significance of this distribution may relate to areas with large numbers of antigen recognition sites on the lymphocyte membrane.
VENTILATION, CARDIAC FREQUENCY AND PATTERN OF BREATHING DURING EXERCISE IN MEN EXPOSED TO O‐CHLOROBENZYLIDENE MALONONITRILE (CS) AND AMMONIA GAS IN LOW CONCENTRATIONS
Authors: Cole T. J. , Cotes J. E. , Johnson G. R. , de V. Martin H. , Reed J. W. , Saunders M. J. 
Published: December 2014

Ventilation minute volume, tidal volume and cardiac frequency during submaximal exercise have been measured in healthy young soldier volunteers exposed to O‐chlorobenzylidene malononitrile (CS) and ammonia gas in concentrations respectively of 0·16 to 4·4 mg.m‐3 and 50 to 344 mg.m‐3. The response of ventilation minute volume to the two gases is apparently similar; both gases cause1 a reduction of, on average 6%. With low doses this reflects a diminution in respiratory frequency whereas with higher doses it is due to a reduction in tidal volume which is accompanied by tachypnoea.The findings may result from stimulation successively of receptors in the larynx and of irritant receptors in the large airways of the lung. The pain which is a feature of exposure to CS but not to ammonia is due to stimulation of other so far unidentified receptors. Neither gas has a direct effect upon the exercise cardiac frequency.
An Electrophysiological Study of Neurones in the Substantia Gelatinosa Rolandi of the Cat's Spinal Cord
Authors: Cervero F. , Iggo A. , Molony V. 
Published: December 2014

Single unit neuronal activity has been recorded in the Substantia Gelatinosa Rolandi (SG) of the lumbar spinal cord of chloralose anaesthetized and gallamine paralysed cats. High impedance, fine tipped glass microelectrodes were used to record from the neurones of the SG. A set of five criteria was laid down to differentiate activity generated by SG neurones from activity produced by other neuronal elements. One hundred and ten neurones satisfied all the criteria and the sample consisted of 78 extracellularly and 32 intracellularly recorded SG neurones. The responses of these neurones to natural stimulation of the skin have been analysed. The majority (86%) showed a conspicuous and persistent background activity in the absence of intentional stimulation and a cutaneous receptive field from which they could be inhibited. These SG neurones have been called ‘inverse’ neurones because their response characteristics were the mirror image of larger neurones in Laminae I, IV and V of the dorsal horn. The background activity of the ‘inverse’ SG neurones was post‐synaptically generated; different in pattern from that of larger and deeper dorsal horn neurones and dependent on the afferent drive to the SG neurones. Three main groups of ‘inverse’ SG neurones could be distinguished according to the kind of natural stimulation that produced inhibition: (i) Class ‘inverse’ 1 ([unknown]), inhibited only by non‐noxious stimulation of the skin. (ii) Class ‘inverse” 2, ([unknown]) inhibited by both noxious and non‐noxious stimulation and (iii) Class ‘inverse’ 3 ([unknown]), inhibited only by noxious stimulation. Class [unknown] SG neurones were excited by noxious stimulation of their receptive fields and Class [unknown] SG neurones were activated by non‐noxious stimulation of theirs.It is proposed that SG neurones control the transmission of all sensory messages through the spinal cord by tonically inhibiting the larger dorsal horn neurones in the absence of stimulation and by selectively releasing this inhibition during periods of stimulation.
Responses of Systemic Vascular Smooth Muscle to Hypoxia
Authors: Ebeigbe A. B. , Pickard J. D. , Jennett Sheila 
Published: December 2014

The rapidity and extent of hypoxic relaxation of vascular smooth muscle (VSM) from different systemic vessels is relevant to the study of mechanisms of vasodilatation in different vascular beds. Variations between sites may also assist understanding of the link between oxygen tension and mechanical activity, which has been shown not to be a simple deprivation of aerobic processes.Strips of rat portal vein (RPV), rabbit ear artery (REA) and rabbit common carotid artery (RCC) were studied under isotonic conditions, contracted by 10–6 noradrenaline (NA). Reduction of Po2 to less than 3KPa during NA contraction led to relaxation which was rapid and 90% complete in RPV, rapid and 60% in REA: the relaxation began when tissue Po2 was decreasing and was not lower than 5·5 K Pa. RCC responded slowly and only some strips relaxed. The rapidity and magnitude of relaxation for each type of vessel was comparable to that produced by removal of external calcium. Also for any one type of VSM the response to NA was abolished or diminished to a similar extent by preliminary exposure to hypoxia, or by preliminary removal of calcium. Preliminary hypoxia diminished 50mmol.l–1 K+ contractions as much as it diminished NA contractions.Preliminary 1—2 hour exposure to hyperoxia diminished the subsequent relaxant effect of hypoxia. Inhibition of glycolysis (iodoacetic acid) had no effect on normoxic NA contraction or on hypoxic relaxation, but prevented or diminished the subsequent recovery on reoxygenation. Low oxygen tension appears to act in VSM as though it interferes with net influx or utilisation of external calcium.
The Effects of pH on the Sodium‐Withdrawal Contractures Evoked from Frog Atrial Trabeculae
Authors: Chapman R. A. 
Published: December 2014

Contractures can be evoked from frog atrial trabeculae by raising extracellular pH in Na‐free fluid after the spontaneous relaxation of the teision evoked by removineg extracellular Na. These alkalinity contractures are unffected by local anaesthetics but are absent following a brief perfusion with Ca‐free fluid containing EGTA. The application of ammonium chloride produces similar‐contractures which are unaffected by perfusion with Ca‐free fluid but are partially inhibited by local analesthetics. Perfusioni by solution containing a high Pco2 fails to induce contractures.The relationship between [Na]o and tension is altered by changing extracellur pH: acidic fluids below pH 6·0 reduce tension and alkaline fluids increase tenision over the whole range. NH4Cl has the same effect as alkalinc fluids while CO2‐conitaining flid has no effect. These results can be interpreted if the effects of variation of extracelluar pH. on Na‐withdrawa; contractures, are mediated by changes in intracellular pH which in turn affect the Ca‐sensitivity of the contractile proteins.
THE RENAL KALLIKREIN‐KININ SYSTEM AND SODIUM EXCRETION
Authors: Mills Ivor H. 
Published: December 2014

Renal kallikrein is a glandular type kallikrien situated in the distal tubular cells and is released into both the urine and the renal lymph. In the vasculature it lowers blood pressure and increases vascular permeability. Blood volume expansion with 0·9% saline or 2·5% glucose leads to a large increase in kallikrein release which, by its effect on the vasculature, helps to maintain dynamic equilibrium. Kallikrein is also released by increase of renal artery pressure or by renal vasodilators. Very small doses of noradrenaline release kallikrein via prostaglandin E as intermediate. Hypertensive doses of angiotensin release kallikrein, partly via prostaglandin and partly by a direct pressure effect. During escape from the sodium‐retaining effect of steroids, kallikrein excretion is increased but it is not released by the acute infusion of aldosterone into the renal artery.The kallikrein‐kinin system antagonizes the renin‐angiotensin system, causes dilution of urine and increases sodium excretion unless renal artery pressure is low. Increased blood pressure can produce natriuresis without involving the kallikrein system, perhaps through release of natriuretic hormone.
LOCAL CONTROL OF TESTICULAR FUNCTION
Authors: Sharpe Richard M. 
Published: December 2014

This review has shown that local control of testicular function exists at three different levels. (1) Regulation of the entry of substances into the testis via the operation of selective barriers at the level of the capillary endothelium, myoid layer and Sertoli cell tight junctions, and by control of the rate of interstitial fluid formation which is the medium for transport into and within the testis. These mechanisms permit the creation of specific micro‐environments around the Leydig cells and outside of the seminiferous tubules as well as within the tubules, prerequisites for the local interaction and communication summarized below. (2) Regulation of spermatogenesis by co‐ordination of changes in hormone responsiveness and function of the Sertoli cells with the requirements of the associated germ cells, this varying according to the stage of the spermatogenic cycle. These changes involve regulation of germ cell multiplication, their differentiation and translocation from the basal to the adluminal compartment of the seminiferous tubule and their release into the lumen. (3) Interaction between the seminiferous tubules and the Leydig cells via various factors. The purpose of this interaction is not certain but in the prepubertal testis it probably co‐ordinates development of the tubules and Leydig cells, whilst in the adult testis it probably functions to regulate the steroidogenic responsiveness of the Leydig cells in accordance with the stage‐dependent requirements of the adjacent seminiferous tubules.Local control mechanisms within the testis therefore appear to co‐ordinate the function of the different cell types in the two testicular compartments and, as this is essential for normal function of the testis, the importance of local factors is self‐evident. In each of the three areas there is still only limited information as to the precise operation of the various mechanisms and even less is known about the identity of the co‐ordinating agents. But, as most of the available information derives only from the last three years, the gaps in our knowledge are to be expected and it is certain that the next few years will see major advances in this area. If the interpretation of the data offered in this review proves accurate then we are on the threshold of a revolution in our understanding of the control of testicular function, and of spermatogenesis in particular. This can only lead to improved methods for regulation of fertility in the male.
IMMUNOCYTOCHEMISTRY AND NEUROBIOLOGY
Authors: Cuello A. Claudio , Priestley John V. , Sofroniew Michael V. 
Published: December 2014

Immunocytochemistry enables the localization of transmitter‐related antigens in tissue sections at either the light microscopic or the electron microscopic level. In the case of neuropeptides and certain transmitters (e.g. serotonin) it has been possible to produce antibodies directed against the putative transmitter itself. In other cases it has not been possible to produce useful antibodies against transmitters but antibodies have been raised against enzymes involved in transmitter metabolism (e.g. tyrosine hydroxylase, glutamic acid decarboxylase) and these antibodies are suitable markers for transmitter systems.Successful immunostaining with an antibody depends on a number of factors, two of the most important being the fixation of the antigen in the tissue and the visualization of the primary antibody once it has bound to the antigen. Techniques available for the visualization of bound primary antibody include the indirect‐labelled immunofluorescence procedure and the unlabelled peroxidase‐antiperoxidase (PAP) procedure. Direct‐labelled immunocytochemistry is not now widely used but is likely to become increasingly important with the introduction of monoclonal antibodies and the development of techniques for the simultaneous localization of multiple antigens. Monoclonal antibody procedures also allow the production of antibodies against antigens which are difficult to purify such as certain transmitter markers (e.g. choline acetyltransferase) and constituents of neuronal membranes.Immunocytochemistry allows the production of detailed maps of the distribution of putative transmitters in the nervous system and in combination with tract tracing procedures is being used increasingly to identify transmitters in neuronal circuits. It has also been important in establishing the transmitter status of various neuroactive compounds in single neurones. Immunocytochemistry can be carried out on post‐mortem samples and is providing information on transmitter distribution in normal and abnormal human brain.
COLLOIDAL GOLD AND BIOTIN‐AVIDIN CONJUGATES AS ULTRASTRUCTURAL MARKERS FOR NEURAL ANTIGENS
Authors: Van Den Pol Anthony N. 
Published: December 2014

The use of two new reagents, biotin‐avidin conjugates and colloidal gold particles, for ultrastructural immunocytochemistry has been reviewed, and their potential for immunocytochemistry in the central nervous system has been discussed. Although these compounds have been used very little in the C.N.S. in the past, with their high sensitivity, versatility, and potential for simultaneous localization of two antigens with two electron dense markers, these reagents may prove very useful for answering a number of neural questions.Colloidal gold adsorbed to immunoglobulins can be used for light microscopic observation, and owing to its high electron density and ability to readily adsorb to immunoglobulins, protein A, and antigen‐carrier complexes, it also serves as an excellent immunomarker at the ultrastructural level. Several procedures have been described for the use of pre‐and post‐embedding immunostaining with colloidal gold particles. Different size gold particles, adsorbed to different antibodies can be used for pre‐and post‐embedding staining of different antigens in the same tissue. While at the light microscopic level only the large particles are visible as a pink haze, a fluorescent step can be added to allow easy identification and characterization of neurones labelled with any size colloidal gold, even if the pink colour of the gold is not visible. These same sections can subsequently be studied ultrastructurally. Unlike enzymatic methods, gold particles have less tendency to obscure ultrastructure.Biotin can be easily conjugated to immunoglobulins and, due to its high affinity for avidin (1015 M−1) which has four biotin binding sites, can be localized with avidin markers, or biotin‐avidin‐ marker complexes. Some procedures such as the avidin‐biotin‐peroxidase complex are extremely sensitive. Biotin and avidin can be bound to a number of different markers including peroxidase, colloidal gold, and ferritin.Photomicrographs from our hypothalamic work have been used to illustrate the histological results of some of the procedures described.
THE EFFECT OF DAY LENGTH ON THE DURATION OF PREGNANCY AND THE ONSET OF PARTURITION IN THE RAT
Authors: Flint A. P. F. , Heap R. B. , Ingram D. L. , Walters D. E. 
Published: December 2014

Rats mated under normal lighting conditions of a 24 h day were transferred to a sound‐proof room with period lengths (T) of 24 h (12 h light and 12 h dark, 12L:12D), or 22 h (11L:11D). During the first 15 d of pregnancy the rats were kept together in a large enclosure and the locomotor activity of the group was recorded. From day 15 they were kept separately, in cages, and from day 21 the number of litters born was noted every 3 h.On 12L:12D, rats displayed well defined periods of activity which were closely related to photoperiod. Mean activity was greatest in the dark, and overall activity declined after day 13 of gestation. On 11L:11D, coupling of locomotor activity to the dark phase was retained initially, but was not sustained throughout the period of study. Activity in the light was comparable to that in the dark at the time when the light:dark cycles of 11L:11D became reversed relative to those of 12L:12D.Rats on a 24 h day had a peak time of delivery at 519 h after mating (21·6 cycles of 12L:12D) and those on a 22 h day at 527 h (24·0 cycles of 11L:11D; difference, P 〈 0·002). The 11L:11D cycle therefore increased rather than decreased the duration of pregnancy, implying that elapsed time rather than the number of light:dark cycles experienced has the greater influence on the length of gestation. Of the animals on a 24 h day 76% had their litters in the light phase of the cycle, whereas only 36% of those on a 22 h day gave birth in the light (P 〈 0·02).
POST‐TRANSLATIONAL MODIFICATION OF PEPTIDE MESSENGERS IN THE GUT
Authors: Dimaline R. 
Published: December 2014

Recombinant DNA technology has enabled valuable information to be obtained on the precursors of gastrointestinal regulatory peptides. A number of precursors such as progastrin and proCCK contain a single recognized biologically active sequence, while others contain multiple active sequences. Some of the latter group such as proenkephalin contain repeated copies of a single peptide sequence, some such as proVIP and proglucagon contain related, but not identical, biologically active peptides, and others such as proopiomelanocortin contain unrelated active sequences. However, while cDNA sequencing studies reveal the potential secretory products available within precursors, they provide no information on the actual cleavages and prosthetic modifications that occur. Some prediction of processing events can be made from the occurrence of consensus sequences of amino acids, but confirmation is possible only by isolation and characterization of the products of the post‐translational processing.This is of particular physiological significance because in many instances processing occurs in a cell‐specific manner, such that a single precursor may give rise to several products with a range of biological activities. For this reason it is important that studies of post‐translational processing keep pace with the ever increasing number of precursor sequences deduced by recombinant DNA technology.
MECHANISMS OF WATER TRANSPORT BY EPITHELIAL CELLS
Authors: Tripathi Subrata , Boulpaep Emile L. 
Published: December 2014

Isosmotic transport of fluid across epithelial cell layers occurs by intraepithelial mechanisms that are not fully understood. Newer methods of measuring water flows across epithelia with higher resolution should now permit some key issues regarding solute‐linked water transport to be clarified. Unstirred‐layer effects are not likely to be serious sources of error in these measurements with judicious choice of experimental conditions.Progress in ultrastructural stereology has shown that in the proximal tubule most of the transporting membrane is located in the basal aspects of cells, making models based on a hyperosmolar lateral compartment less relevant. The current models of simple transcellular osmosis, though appealing for this simplicity, fail to account for some major experimental findings. Experimental design and methodological limitations have not yet achieved rigorous testing of whether or not epithelia can produce a perfectly isosmotic absorbate without any transepithelial driving forces.A better understanding of the mechanism of translocation of water through the lipid bilayer, the plasma membrane proteins, and special membrane structures like the tight junctions would significantly contribute to our knowledge of the mechanisms and intraepithelial routes by which water is transported by epithelia.