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PubMed1988

Bistability of alpha-motoneurones in the decerebrate cat and in the acute spinal cat after intravenous 5-hydroxytryptophan.

1. In the preceding paper (Crone, Hultborn, Kiehn, Mazieres & Wigström, 1988) it was shown that a short-lasting synaptic excitation ('on' stimulus) of extensor motoneurones (primarily triceps surae) in the decerebrate cat often resulted in a maintained excitability increase, which could be reset by a short-lasting inhibitory stimulus train ('off' stimulus). In the present experiments intracellular recording from triceps surae motoneurones and the electroneurogram (ENG activity) from triceps surae nerve branches were performed in parallel. 2. Sustained firing of individual triceps surae motoneurones was most often recorded in parallel with the maintained ENG activity following a synaptic 'on' stimulus. When the motoneurone was silenced, by a hyperpolarizing current through the microelectrode, there was no sign of on-going synaptic excitation during the maintained ENG activity following an 'on' stimulus. It was therefore suggested that voltage-dependent intrinsic properties of the motoneurones themselves could be responsible for the maintained firing. 3. In confirmation of this hypothesis it was found that short-lasting depolarizing current pulses through the recording microelectrode could trigger a self-sustained firing in the motoneurone provided that the bias current (i.e. the holding potential) was kept within certain limits. Hyperpolarizing current pulses terminated the firing. When the spike-generating mechanism was inactivated (by long-lasting excessive depolarization) similar depolarizing and hyperpolarizing current pulses could initiate and terminate plateau potentials in the motoneurones. By grading the depolarizing current pulses it was found that the plateau potentials were of all-or-none character, typically around 10 mV in amplitude. The two levels of excitability which can be triggered by short-lasting excitation and inhibition of the motoneurones is referred to as 'bistable' behaviour of the motoneurones. 4. After an acute spinal transection, in the unanaesthetized cat, the bistable behaviour of the motoneurones disappeared. However, it reappears following intravenous injection of the serotonin precursor 5-hydroxytryptophan (50-120 mg/kg). 5. Individual triceps surae motor units were recorded by selective EMG electrodes during tonic stretch reflexes in the decerebrate preparations. Based on an analysis of their firing pattern during lengthening and shortening (or vibration) of the muscle it is suggested that plateau potentials in motoneurones are recruited during the tonic stretch reflex. Furthermore, it is argued that a quantitatively important part of the depolarization of motoneurones during the tonic stretch reflex indeed originates from these plateau potentials.(ABSTRACT TRUNCATED AT 400 WORDS)

5-Hydroxytryptophan↗
PubMed1989

Retinal sensitivity in hereditary retinal degeneration in Abyssinian cats: electrophysiological similarities between man and cat.

The functional and electrophysiological similarities in the changes in the electroretinogram (ERG) of man and cat affected by hereditary retinal degenerative disease were studied. The results of a series of log intensity-amplitude studies in a group of young affected Abyssinian cats were fitted to the Naka-Rushton relationship by means of a mathematical package on the University of London mainframe. The analysis showed that the amplitude of the maximum dark-adapted b-wave was significantly reduced by the end of the period studied but that the value of k, a variable inversely equivalent to retinal sensitivity, was only slightly reduced by the retinal degenerative process. The electrophysiological findings thus are similar to those found in cases of human diffuse dominantly inherited retinitis pigmentosa.

Animals↗
PubMed1986

Pleural effusion and anicteric hepatitis associated with cat-scratch disease. Documentation by cat-scratch bacillus.

Prior to the discovery of the coccobacillus in the lymph nodes of patients with cat-scratch disease by Wear and associates, the diagnosis was based on clinical findings and a nonstandardized skin test. Atypical cases either remained an enigma or were questioned as to accuracy of diagnosis. We present here a case of cat-scratch disease associated with pleural effusion, anicteric hepatitis, and other systemic manifestations confirmed by identification of the coccobacillus. It is the first association with a pleural effusion. With the Warthin-Starry stain, we anticipate a redefinition of this disease. The confirmation of atypical cases will help broaden the clinical spectrum, as well as guide us to consider this diagnosis where its classic manifestations may be absent.

Adult↗
PubMed1994

[The pork-cat syndrome or crossed allergy between pork meat and cat epithelia (1)].

This work is a study of the frequency of the association between sensitivity to pork meat and cat epithelia. Comparison with a reference population that was not sensitized to pork meat, shows that this association is highly significant. This suggests therefore the possibility of a crossed allergenicity. If there is a real crossed allergenicity between pork meat and cat epithelia, we suggest that this crossed allergenicity is without doubt much greater and concerns more the meats and epithelia of mammals.

Animals↗
PubMed2001

A unified theory of enzyme kinetics based upon the systematic analysis of the variations of k(cat), K(M), and k(cat)/K(M) and the relevant DeltaG(0 not equal) values-possible implications in chemotherapy and biotechnology.

To elucidate the kinetic properties of critical enzymatic situations that have previously escaped classification, we performed a systematic analysis of all the possible variations of the kinetic constants k(cat,) K(M,) and k(sp) = k(cat)/K(M,) encompassing all aspects of enzymology. The equation gives a total of thirteen theoretically possible cases, comprising the reference case plus 12 different sets of variations, which can be divided into six principal cases and six specular ones. The six relevant cases are examined individually in the context of each of the main chapters of enzymology, i.e. as regards mechanism of action, specificity of substrate and isoenzyme, reversible and irreversible inhibition, and mutation of residues (enzyme evolution and enzyme engineering). Some critical cases where k(sp) does not hold as a specificity index are classified for the first time. Interestingly, the six possible cases correspond to the five known cases of reversible inhibition (competitive, non-competitive, incompetitive, mixed competitive/non-competitive, and mixed incompetitive/non-competitive) plus an additional case of biphasic nature (activation-inhibition), which is crucial for a full understanding of specificity and which leads us to propose some modification to the definition of enzyme specificity. The systematic approach to enzymology outlined herein could find practical applications in various sectors of biotechnology, including chemotherapy.

Binding, Competitive↗
PubMed1987

Quantitative analysis of the choline acetyltransferase-immunoreactive axonal network in the cat primary visual cortex: I. Adult cats.

The laminar distribution of cholinergic axons was analyzed quantitatively in the visual cortex of adult cats by using immunocytochemistry with a monoclonal antibody against choline acetyltransferase (ChAT). ChAT(+) fibers and varicosities were counted at different locations within area 17 and the distribution patterns in various animals were compared. Choline acetyltransferase-immunoreactivity was localized in fine, varicose fibers, which were present in all layers of the visual cortex. The density of labeled fibers was highest in layer I, which contained 14% of all fibers and 19.5% of all varicosities, and decreased toward deeper layers. The number of varicosities decreased more markedly toward deeper layers than the frequency of fibers. These distribution patterns were very consistent, showing only slight intra- and interindividual variability.

Animals↗
PubMed1988

Postnatal development of cat hind limb motoneurons. I: Changes in length, branching structure, and spatial distribution of dendrites of cat triceps surae motoneurons.

The postnatal development of length, branching structure, and spatial distribution of dendrites of triceps surae motoneurons, intracellularly stained with horseradish peroxidase, was studied from birth up to 44-46 days of postnatal (d.p.n.) age in kittens and compared with corresponding data from adult cats. The number of dendrites of a triceps surae motoneuron was about 12, and the arborization of each dendrite generated an average of 12-15 terminal branches. There was no net change in the number of dendrites of a neuron or in the degree of branching of the dendrites despite the occurrence of both a transient remodeling of the dendritic branching structure and changes of the spatial distribution of the dendritic branches during postnatal development. The perisomatic territory in the transverse plane occupied by the dendritic branches of a motoneuron increased in parallel with the overall growth of the spinal cord. Thus, the relative size of the dendritic territory in this plane was kept almost constant, whereas dendritic branches projecting in the rostrocaudal direction grew much faster than the spinal cord and also became more numerous. At birth the rostro-caudal dendritic span of individual motoneurons bridged 1:6 to 1:5 of the L7 spinal cord segment length; this figure was 1:3 at 22-24 d.p.n. Hence, in this direction, the growing dendritic branches invaded novel dendritic territories. The change in dendritic branch length from birth to 6 weeks of age corresponded to an average growth rate of 2 to 4 microns per dendritic branch and day, which implies that the total increase in length of the dendrites of a neuron could amount to 1 mm/day. The increase in branch length did not occur in a uniform or random manner; instead, it followed a spatiotemporal pattern with three phases: From birth to 22-24 d.p.n., growth was particularly prominent in greater than or equal to 3rd order preterminal and 2nd through 6th order terminal branches. From 22-24 to 44-46 d.p.n., a large increase in branch length confined to terminal branches of greater than or equal to 3rd branch orders was observed. As indicated by topological analysis, this length increase was probably due in part to a resorption of peripheral dendritic branches during this stage of development. From 44-46 d.p.n. to maturity, the increase of dendritic branch length was restricted to preterminal branches of low (less than or equal to 4th) branch order.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1982

Interlimb coordination in cat locomotion investigated with perturbation. I. Behavioral and electromyographic study on symmetric limbs of decerebrate and awake walking cats.

During locomotion of decerebrate and awake walking cats, perturbation (mechanical tap) was applied to the paw dorsum of the left forelimb (LF), and the responses of both forelimbs were recorded cinematographically and electromyographically (EMG). When the tap was applied during the LF stance phase, the duration of the ongoing LF stance was shortened by 10%; in the right forelimb (RF), the duration of the concomitant swing was shortened by 32%. A tap during the LF swing phase prolonged the duration of the ongoing LF swing phase and the concomitant RF stance phase by 55 and 15%, respectively. Analysis of RF joint angle excursions showed that the shortening of the RF swing phase was related mainly to acceleration of extension movement in the late swing phase; the prolongation of the RF stance phase was related to prolonged extension movement in the late stance phase. While EMG activities were relevant to these limb movements, a notable observation was that, by tapping the LF during the LF stance phase, EMG activity in the RF extensor started well before onset of the elbow extension movement to place down the limb; without the tap, the extensor activity started shortly after onset of the extension. Closely related to changes in phase durations of each forelimb, the period of bisupport phase where both forelimbs were in stance, was retained for more than 40% of that of unperturbed steps, even when the RF or LF made the first touchdown after the tap. The rostrocaudal level at RF touchdown after the tap was comparable to unperturbed steps. These findings on interlimb relation suggest that neural control ensures coordinated movements between symmetric limbs during locomotion.

Animals↗
PubMed1982

Interlimb coordination in cat locomotion investigated with perturbation. II. Correlates in neuronal activity of Deiter's cells of decerebrate walking cats.

The effects of mechanical stimulation (tap) on single unit activity of Deiter's neurons were analysed in walking cats decerebrated at the premammillary level. Deiters' neurons projecting to the ipsilateral cervical, but not to the lumbosacral, spinal cord (C-Deiters' neurons) were identified by antidromic activation, cerebellar stimulation, and localization of the neurons. During each unperturbed cycle of quadrupedal locomotion, most C-Deiters' neurons showed two frequency modulation peaks in their impulse discharges: one (A peak) in the late swing (E1) or the early stance (E2) phase, the other (B peak) in the late stance (E3) or the early swing (F) phase, of the ipsilateral forelimb. The A peak started to rise shortly before the ipsilateral forelimb was placed. When mechanical perturbation was applied during locomotion to the paw dorsum of the left forelimb (LF) in its stance phase, the ongoing LF stance phase shortened and the simultaneous swing phase of the right forelimb (RF) shortened. Accordingly, in the RF, extensor activity in the swing phase to place down the limb occurred earlier than in unperturbed step cycles. The same LF tap induced a marked enhancement of impulse discharges in C-Deiters' neurons on the right side (with a magnitude of 20-100 imp/s, and the shortest latency of 25 ms). This enhancement was more pronounced than that induced when the perturbation was applied to the LF during its swing phase. The latency manifested a close time relation to the RF extensor activity supporting the postulate that the increased C-Deiters' activity in the RF swing phase contributes to the earlier onset of RF extensor activity which plays an important role in maintaining alternating footfalls after perturbation.

Animals↗
PubMed1993

Allergens in school dust. I. The amount of the major cat (Fel d I) and dog (Can f I) allergens in dust from Swedish schools is high enough to probably cause perennial symptoms in most children with asthma who are sensitized to cat and dog.

BACKGROUND: We investigated the levels of Fel d I and Can f I in dust from tables, chairs, and floors in 29 classrooms in four Swedish schools. METHODS: School authorities were questioned about building characteristics, students were interviewed about their health and exposure to animals, and cleaning personnel were asked about methods and frequency of cleaning. Dust samples were taken from floors and horizontal surfaces of chairs and tables in all classrooms during a 6-week period. RESULTS: Higher amounts of Fel d I were found on chairs (geometric mean, 953 ng per gram of dust) than on tables (525 ng/gm) and floors (134 ng/gm). The concentration of Can f I (5.3 ng/gm) on chairs was 2 to 20 times higher than Fel d I. The concentration of Can f I (200 ng/gm) in dust from floors was twice as high as that of Fel d I. The concentration of Can f I on chairs was within the range previously found by other investigators in houses with dogs. CONCLUSIONS: Since the levels of both Fel d I and Can f I were much higher on chairs than on floors, we hypothesize that allergen is brought to schools on the clothes of students and teachers. We conclude that the levels of the two major allergens from furred pets (i.e., Fel d I and Can f I) in Swedish schools are probably high enough to sensitize children and to induce asthma in most children who are allergic to cats or dogs.

Adult↗
PubMed1987

X-cells in the cat retina: relationships between the morphology and physiology of a class of cat retinal ganglion cells.

1. The morphology of 21 physiologically characterized X-cells in the cat retina was studied using intracellular recording and injection with horseradish peroxidase. The data from these experiments were used to test directly the relationships between specific structural and functional characteristics of a sample of individual retinal ganglion cells of the same anatomical and physiological class. Where possible, the response properties of 53 other retinal X-cells that were not successfully injected and recovered are compared with those of the labeled sample. These comparisons, which included conduction velocities (both intraretinal and extraretinal) and receptive-field size, indicate that the labeled X-cells are a representative sample of the population of retinal X-cells at corresponding eccentricities. 2. The somata of this group of injected retinal X-cells increase in size with increasing distance from the area centralis up to 13 degrees eccentricity (the greatest distance from the area centralis at which an X-cell was injected and recovered). The soma sizes of this sample of retinal ganglion cells range from 143.5 to 529.9 micron 2 (diam = 13.5-26.0 micron). Comparison of the soma sizes of the injected and recovered retinal X-cells with those of 300 Nissl-stained neurons at comparable eccentricities in the same retinae indicate that the injected sample had soma sizes that are consistent with their classification as "medium-sized" retinal ganglion cells (5, 69, 74). 3. All of the physiologically characterized retinal X-cells of this study have the compact dendritic arbors described to the morphological class of retinal ganglion cell called beta-cells by Boycott and Wässle (5). The dendrites of some of these neurons have many spinelike appendages, whereas those of other cells are nearly appendage free. We found no obvious correlation between the presence of dendritic appendages and any specific response characteristic ("ON-" or "OFF-center", etc). Like the size of the soma, both the diameter of the dendritic arbors of these cells, and the number of primary dendrites (those dendrites that originate directly from the soma), increase with increasing distance from the area centralis. 4. Since both morphological and physiological data were obtained for these neurons, it is possible to describe the relationship between the size of the receptive-field center and the diameter of the dendritic arbor for individual retinal ganglion cells. These comparisons show that the relationship between the anatomical measure and this response parameter for the entire sample of labeled X-cells is not as strong as had previously been suggested.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Influence of adrenergic receptors on ovarian progesterone secretion in the pseudopregnant cat and oestradiol secretion in the oestrous cat.

The infusion of isoprenaline or propranolol into the abdominal aorta of the pseudopregnant cat caused an increase or decrease respectively in the ovarian progesterone secretion rate. These observations suggest that the sympathetic innervation of the ovary has a physiological influence on normal progesterone secretion, and this mechanism may explain stress-related increases in progesterone concentrations. The infusion of isoprenaline or propranolol after the stimulation of follicular growth had no consistent or convincing effect on oestradiol secretion.

Animals↗
PubMedDate not supplied

Inverse correlation between right-paw use and body weight in right-pawed male cats and left-pawed female cats.

The association between paw preference and body weight was studied in cats. In right-pawed males, the right minus left (R-L) paw use significantly decreased as the body weight increased. There was no significant correlation between these parameters in left-pawed males as well as in right-pawed females. In left-pawed females, the frequency of the left-paw use increased as the body weight increased. These results partly supported those in humans (Tan, in press). It was suggested that hormonal factors affecting body weight may also influence cerebral lateralization and consequently paw preference. The best possibility for these hormones appears to be testosterone.

Animals↗
PubMed1986

[Responses of neurons of the parietal association cortex of the cat to acoustic stimulation before and after suppression of the auditory cortex in the cat].

The aim of this work was to study the influence of auditory cortex suppression in cat on response patterns of the parietal associative cortex neurons responding to different frequency tones. Suppression was performed by two methods: bilateral isolation and application of 6% nembutal solution on the cortex surface. Frequency-thresholds curves were plotted for all neurons studied. Prior to suppression the majority (84%) of studied neurons had one or two characteristic frequencies. After suppression the percentage of such cells fell to 63% of all responding neurons. Frequency range to which neurons could respond was altered as well. Normally almost all neurons tested could respond to a wide spectrum of presented frequencies. After suppression 69% of neurons did not respond to tones above 8-10 kHz. This may indicate that mainly information about high frequency tones is transmitted via the auditory cortex. The possibility that associative thalamic nuclei are the main source of acoustic information for parietal associative cortex neurons is discussed.

Animals↗
PubMed1979

[Structure and biometric indices of the lumbar ganglia of the sympathetic trunk of normal cats and cats subjected to hormonal stimulation].

The structure of different components from lumbar ganglia of the cat sympathetic trunk were studied in norm and 6h after intramuscular administration of prednisolone (5 mg/kg). Paraffin sections were stained with azocramine after Heidenhain, Wallart and Houette, azure II -- eosin. Biometry of different ganglial structures was performed by G.G. Avtandilov's dotted method. It was demonstrated that as a response to prednisolone administration, certain morphological changes appeared in all ganglial components. The walls of capillaries grew thicker, endothelial nuclei protruded into their lumen. Collagenous fibres of the connective tissue capsule and ganglial stroma grew thicker and acquired twisted appearance, the amount of the basilar substance increased. Simultaneously, there was a sharp increase of the nuclear section area in perineuronal ganglia. The total area of neuronal sections in the ganglia also increased at the expense of both increasing area of neuronal cytoplasm and hypertrophy of their nuclei.

Animals↗