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PubMed2006

Changes in the histaminergic system during vestibular compensation in the cat.

To determine how the histaminergic system is implicated in vestibular compensation, we studied the changes in histidine decarboxylase (HDC; the enzyme synthesizing histamine) mRNA regulation in the tuberomammillary (TM) nuclei of cats killed 1 week, 3 weeks and 3 months after unilateral vestibular neurectomy (UVN). We also used one- and two-step bilateral vestibular neurectomized (BVN) cats to determine whether HDC mRNA regulation depended on the asymmetrical vestibular input received by the TM nuclei neurons. In addition, we analysed the HDC mRNA changes in the TM nuclei and the recovery of behavioural functions in UVN cats treated with thioperamide, a pure histaminergic drug. Finally, we quantified binding to histamine H3 receptors (H3Rs) in the medial vestibular nucleus (VN) by means of a histamine H3R agonist ([3H]N-alpha-methylhistamine) in order to further investigate the sites and mechanisms of action of histamine in this structure. This study shows that UVN increases HDC mRNA expression in the ipsilateral TM nucleus at 1 week. This increased expression persisted 3 weeks after UVN, and regained control values at 3 months. HDC mRNA expression was unchanged in the one-step BVN cats but showed mirror asymmetrical increases in the two-step BVN compared to the 1 week UVN cats. Three weeks' thioperamide treatment induced a bilateral HDC mRNA up-regulation in the UVN cats, which was higher than in the untreated UVN group. Binding to histamine H3Rs in the MVN showed a strong bilateral decrease after thioperamide treatment, while it was reduced ipsilaterally in the UVN cats. That such changes of the histaminergic system induced by vestibular lesion and treatment may play a functional role in vestibular compensation is strongly supported by the behavioural data. Indeed, spontaneous nystagmus, posture and locomotor balance were rapidly recovered in the UVN cats treated with thioperamide. These results demonstrate that changes in histamine levels are related to vestibular compensation.

Adaptation, Physiological↗
PubMed1992

[Clinicobacteriological study of Pasteurella multocida as a zoonosis (1). Condition of dog and cat carriers of Pasteurella, and the influence for human carrier rate by kiss with the pets].

Pasteurella multocida is a gram-negative short rod-shaped bacteria, which is a part of the indigenous flora of the oral cavity of many animals other than man. The number of reports on cases of infections with this bacterium due to animal bites and/or scratches, bacterial infections of the respiratory tract, sepsis due to this organism and death caused by the bacteria have been increasing in recent years. We investigated P. multocida in the hair and oral cavity of 3 dogs and 29 cats according to the classification of Mutters et al.. We also studied the relationship between the carrier rate for Pasteurella in the oral cavity and kissing of pets in 24 pet owners (3 dogs and 11 cats). No P. multocida was isolated from the hair of neither dogs nor cats. One strain of P. multocida subsp. multocida and two strains of P. stomatis, were isolated from the oral cavity of dogs, and 35 strains of Pasteurella were isolated from the oral cavity of cats. Two strains of P. multocida subsp. multocida, whose biochemical properties were different, were detected in the oral cavity of one cat. In three cats, Pasteurella other than P. multocida subsp. multocida was isolated from the same oral cavity. No Pasteurella was detected in the oral cavity of 19 pet owners who had not kissed their cats, whereas P. stomatis was isolated from the oral cavity of one of 2 pet owners who had kissed their cats and in 2 of 3 pet owners who had kissed their dogs (the same bacteria was isolated from a dog that was being kept by some of these positive pet owners).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

[Survey on Toxocara cati in domestic cats].

A total of 542 domestic cats aged from 1 month to 20 years were investigated for Toxocara cati (T. cati) by means of fecal examination. The cats were classified in the groups according to their kept environment (indoor or outdoor) and age (1-6 month, 7 month-1 year, 2-3 year, 4-5 year and over 6 year). The indoor kept cats were major in all ages, and the friendly relationship was suggested between domestic cats and humans. The parasitic rates of T. cati a higher percentage was noted in the groups of indoor kept cats of 1-6 month (27.1%) than that of outdoor kept cats of 1-6 month (17.9%), 7 month-1 year (18.5%) and 4-5 year (14.3%). The high parasitism of T. cati in indoor kept 1-6 month cats, which are may be closely connected to humans, is an important problem from the public health of view, because of the direct source of visceral larva migraine. The parasitism of T. cati in outdoor kept cats is also a serious matter as the origin of environmental contamination. It suggests that a positive sanitary instruction against an owner seems necessary for prevention of visceral larva migraine in humans.

Animals↗
PubMed2003

In vivo antiretroviral activity of stampidine in chronically feline immunodeficiency virus-infected cats.

Here we report the antiretroviral activity of the experimental nucleoside reverse transcriptase inhibitor (NRTI) compound stampidine in cats chronically infected with feline immunodeficiency virus (FIV). Notably, a single oral bolus dose of 50 or 100 mg of stampidine per kg resulted in a transient >/=1-log decrease in the FIV load of circulating peripheral blood mononuclear cells in five of six FIV-infected cats and no side effects. A 4-week stampidine treatment course with twice-daily administration of hard gelatin capsules containing 25 to 100 mg of stampidine per kg was also very well tolerated by cats at cumulative dose levels as high as 8.4 g/kg and exhibited a dose-dependent antiretroviral effect. One of three cats treated at the 25-mg/kg dose level, three of three cats treated at the 50-mg/kg dose level, and three of three cats treated at the 100-mg/kg dose level (but none of three control cats treated with placebo pills) showed a therapeutic response, as evidenced by a >/=1-log reduction in the FIV load in peripheral blood mononuclear cells within 2 weeks. The previously documented in vitro and in vivo antiretroviral activity of stampidine against primary clinical human immunodeficiency virus type 1 isolates with genotypic and/or phenotypic NRTI resistance, together with its favorable animal toxicity profile, pharmacokinetics, and in vivo antiretroviral activity in FIV-infected cats, warrants further development of this promising new NRTI compound.

Animals↗
PubMed1994

Helicobacter pylori isolated from the domestic cat: public health implications.

Helicobacter pylori has been directly linked with active chronic gastritis, peptic ulceration, and gastric adenocarcinoma in humans. Although a substantial portion of the human population is colonized with H. pylori, the patterns of transmission of the organism remain in doubt, and reservoir hosts have not been identified. This study documents the isolation of H. pylori from domestic cats obtained from a commercial vendor. The isolation of H. pylori from these cats was confirmed by morphologic and biochemical evaluations, fatty acid analysis, and 16S rRNA sequence analysis. H. pylori was cultured from 6 cats and organisms compatible in appearance with H. pylori were observed in 15 additional cats by histologic examination. In most animals, H. pylori was present in close proximity to mucosal epithelial cells or in mucus layers of the glandular or surface epithelium. Microscopically, H. pylori-infected cat stomachs contained a mild to severe diffuse lymphoplasmacytic infiltrate with small numbers of neutrophils and eosinophils in the subglandular and gastric mucosae. Lymphoid follicles were also noted, particularly in the antrum, and often displaced glandular mucosal tissue. Thus, the domestic cat may be a potential model for H. pylori disease in humans. Also, the isolation of H. pylori from domestic cats raises the possibility that the organism may be a zoonotic pathogen, with transmission occurring from cats to humans.

Animals↗
PubMed1996

Molecularly cloned feline immunodeficiency virus NCSU1 JSY3 induces immunodeficiency in specific-pathogen-free cats.

A full-length feline immunodeficiency virus NCSU1 (FIV-NCSU1) genome (JSY3) was cloned directly from FIV-NCSU1-infected feline CD4+ lymphocyte (FCD4E) genomic DNA and identified by PCR amplification with 5' long terminal repeat, gag, env, and 3' long terminal repeat primer sets. Supernatant from FCD4E cells cocultured with JSY3-transfected Crandell feline kidney (CrFK) cells was used as an inoculum. Cell-free JSY3 virus was cytopathogenic for FCD4E lymphocytes but did not infect CrFK cells in vitro. To determine in vivo infectivity and pathogenesis, six young adult specific-pathogen-free cats were inoculated with cell-free JSY3 virus. Provirus was detected at 2 weeks postinfection (p.i.) and was still detectable at 25 weeks p.i. as determined by gag region PCR-Southern blot analysis of peripheral blood mononuclear cell lysates. Infectious virus was recovered from peripheral blood mononuclear cells at 6 and 25 weeks p.i., and an antibody response to FIV was detected by 4 weeks. In the acute phase of infection, JSY3 provirus was found only in the CD4+ lymphocyte subset; however, by 14 weeks p.i., the greatest provirus burden was detected in B lymphocytes. All six cats were panlymphopenic at 2 weeks p.i., CD4+/CD8+ ratios were inverted by 6 weeks p.i., and five of the six cats developed lymphadenopathy by 10 weeks p.i. To determine if the JSY3 molecular clone caused immunodeficiency similar to that of the parental wild-type FIV-NCSU1, the cats were challenged with the low-virulence ME49 strain of Toxoplasma gondii at 29 weeks p.i. Five of six cats developed clinical signs consistent with generalized toxoplasmosis, and three of six cats developed acute respiratory distress and required euthanasia. Histopathologic examination of the severely affected cats revealed generalized inflammatory reactions and the presence of T. gondii tachyzoites in multiple tissues. None of the six age- and sex-matched specific-pathogen-free cats inoculated with only T. gondii developed clinical disease. Our results suggest that the pathogenesis of the molecularly cloned NCSU1 JSY3 is similar to that of wild-type FIV-NCSU1.

Animals↗
PubMed1998

Effects of quarantine on cats and their owners.

The effects of quarantine on 16 cats and their owners were assessed by means of four questionnaires completed by the owners at the beginning of their cat's stay in quarantine, three months later, and two weeks and three months after the cats left quarantine. Changes in body condition were evident in two-thirds of the cats during and at the end of quarantine but not three months later. Mid-way through quarantine, the owners considered their cats were less attached to them, less relaxed, more excitable, more aggressive, more nervous and less playful than before quarantine. When they left quarantine the cats were friendlier, more affectionate and more timid, and three months later they were more affectionate, more nervous and more vocal than before quarantine. When they left quarantine and three months later the cats spent more time with their owners than before quarantine. Most owners visited their cats once or twice a month; the location of the cattery and the limited opening hours restricted the number of visits they made.

Animals↗
PubMed2005

Comparison of xylazine and medetomidine as premedicants for cats being anaesthetised with propofol-sevoflurane.

The effects of premedicating cats with saline, xylazine or medetomidine before anaesthetising them with propofol-sevoflurane were compared. Twenty-four cats were randomly assigned to three groups of eight to receive either 0.25 ml of saline, 0.50 mg/kg of xylazine or 0.02 mg/kg of medetomidine intravenously, and anaesthesia was induced with propofol and maintained with sevoflurane. Medetomidine produced a greater reduction in the induction dose of propofol and fewer adverse postoperative effects than saline or xylazine. Hypoxaemia was observed after induction with propofol in the cats premedicated with saline and xylazine, but not in the cats given medetomidine. The cats treated with medetomidine and xylazine developed profound bradycardia. The blood pressure of the cats premedicated with saline and xylazine decreased, but the blood pressure of the cats premedicated with medetomidine was maintained. The cats premedicated with saline took longer to recover from anaesthesia than the other two groups.

Adrenergic alpha-Agonists↗
PubMed2004

Estrogen's attenuating effect on the exercise pressor reflex is more opioid dependent in gonadally intact than in ovariectomized female cats.

Using gonadally intact female cats, we showed previously that estrogen, applied topically to the spinal cord, attenuated the exercise pressor reflex. Although the mechanism by which estrogen exerted its attenuating effect is unknown, this steroid hormone has been shown to influence spinal opioid pathways, which in turn have been implicated in the regulation of the exercise pressor reflex. These findings prompted us to test the hypothesis that opioids mediate the attenuating effect of estrogen on the exercise pressor reflex in both gonadally intact female and ovariectomized cats. We therefore applied 200 microl of 17beta-estradiol (0.01 microg/ml) with and without the addition of 1,000 microg naloxone, a mu- and delta-opioid antagonist, to a spinal well covering the L6-S1 spinal cord in decerebrated female cats that were either gonadally intact or ovariectomized. The exercise pressor reflex was evoked by electrical stimulation of the L7 or S1 ventral root, a maneuver that caused the hindlimb muscles to contract statically. We found that, in gonadally intact cats, the attenuating effect of estrogen was more pronounced than that in ovariectomized cats. We also found that, in gonadally intact female cats, naloxone partly reversed the attenuation of the pressor response to static contraction caused by spinal estrogen application. For example, in intact cats, the pressor response to contraction before estrogen application averaged 39 +/- 4 mmHg (n = 10), whereas the pressor response 60 min afterward averaged only 18 +/- 4 mmHg (P < 0.05). In contrast, the pressor response to contraction before estrogen and naloxone application averaged 33 +/- 5 mmHg (n = 11), whereas afterward it averaged 27 +/- 6 mmHg (P < 0.05). In ovariectomized cats, naloxone was less effective in reversing the attenuating effect of estrogen on the exercise pressor reflex.

Animals↗
PubMed2002

Effects of intrathecal glutamatergic drugs on locomotion I. NMDA in short-term spinal cats.

Excitatory amino acids (EAA) have been reported to induce fictive locomotion in different in vitro and in vivo preparations in a variety of species through their actions on both N-methyl-D-aspartate (NMDA), and non-NMDA receptors. NMDA-induced intrinsic membrane properties such as intrinsic motoneuronal membrane oscillations and plateau potentials have been suggested to play a role in the generation of locomotion. There is, however, no information on the ability of NMDA in triggering spinal locomotion in awake behaving animals. Because most of the previous work on the induction of locomotion has concentrated on monoaminergic drugs, mainly noradrenergic drugs, the aim of this study is to examine the potential of NMDA in initiating locomotion in chronic spinal cats within the first week after spinalization. Five cats chronically implanted with an intrathecal cannula and electromyographic (EMG) electrodes were used. EMG activity synchronized to video images of the hindlimbs were recorded. The results show that during the early posttransection period (within the 1st week postspinalization), NMDA did not trigger robust locomotion as did noradrenergic drugs. The predominant effects of NMDA were a general hyperexcitability reflected by fast tremor, toe fanning, and an increase in small alternating hindlimb movements with no foot placement nor weight support. During the intermediate phase posttransection (6-8 days), when the cats were able to make some rudimentary steps with foot placement, NMDA significantly enhanced the locomotor performance, which lasted for 24-72 h postinjection. NMDA was also found to increase the excitability of the cutaneous reflex transmission only in early spinal cats. One possible hypothesis for the ineffectiveness of NMDA in triggering locomotion in early spinal cats could be attributed to the widespread activation of NMDA receptors on various neuronal elements involved in the transmission of afferent pathways that in turn may interfere with the expression of locomotion. The marked effects of NMDA in intermediate-spinal cats suggest that NMDA receptors play an important role in locomotion perhaps through its role on intrinsic membrane properties of neurons in shaping and amplifying spinal neuronal transmission or by augmenting the sensory afferent inputs. The long-term effects mediated by NMDA receptors have been reported in the literature and may involve mechanisms such as induction of long-term potentiation or interactions with neuropeptides. The effects of NMDA injection in intact cats and long-term chronic spinal cats will be addressed in a forthcoming companion paper.

Animals↗
PubMed2003

Effects of intrathecal glutamatergic drugs on locomotion. II. NMDA and AP-5 in intact and late spinal cats.

In a previous article, we have shown that, in cats, intrathecal injections of N-methyl-D-aspartate (NMDA) in the first few days after spinalization at T13 do not induce locomotion as in many other spinal preparations. This is in contrast to alpha-2 noradrenergic receptor stimulation, which can trigger locomotion at this early stage. However, it is known that spinal cats do recover spontaneous locomotion in the absence of descending noradrenergic pathways and that the spinal pattern generator must then depend on other neurotransmitters still present in the cord such as excitatory amino acids. In the present paper, therefore we look at the effects of intrathecal NMDA, a glutamatergic agonist, and 2-amino-5-phosphonovaleric acid (AP-5), an NMDA receptor blocker, in both intact and late spinal cats. Low doses of NMDA had no major effect on the locomotor pattern in both intact and late spinal cats. Larger doses of NMDA in the chronic spinal cat initially produced an increase in the general excitability followed by more regular locomotion. AP-5 in intact cats caused a decrease in the amplitude of the flexion reflex and induced a bilateral foot drag as well as some decrease in weight support but it did not prevent locomotion. However, in late spinal cats, the same dose of AP-5 blocked locomotion completely. These results indicate that NMDA receptors may be critical for the spontaneous expression of spinal locomotion. It is proposed that the basic locomotor rhythmicity in cats is NMDA-dependent and that normally this glutamatergic mechanism is modulated by other neurotransmitters, such as 5-HT and NA.

2-Amino-5-phosphonovalerate↗
PubMed1989

W-and Y-cells in the C layers of the cat's lateral geniculate nucleus: normal properties and effects of monocular deprivation.

1. Previous studies have shown that rearing with monocular visual deprivation (MD) produces a loss of Y-cells and a reduction in spatial resolution among X-cells in layers A and A1 of the cat's dorsal lateral geniculate nucleus (dLGN). However, there have been no studies of the effects of visual deprivation on the function of the retinogeniculate W-cell pathway, which terminates in the C layers of the dLGN. It also is not known if Y-cells in the C layers are affected by MD in the same way as Y-cells in the A layers. These questions were addressed by the present experiment. 2. Single-cell recordings were made from the C layers of 5 normal adult cats (112 cells) and from the nondeprived (94 cells) and deprived (95 cells) C layers in 10 cats monocularly deprived by lid suture for 3-7 yr. The cells were classified as X, Y, or W on the basis of their receptive-field properties and responses to electrical stimulation of the optic chiasm. In addition, quantitative measures were made of responses to sine-wave gratings of different spatial frequencies. 3. Receptive-field organization, receptive-field center size, spatial and temporal linearity to counterphased sine-wave gratings, and latency to optic chiasm stimulation were similar for C-layer cells in normal cats and in the deprived and nondeprived layers of MD cats. On the basis of these properties, 23% of normal layer-C cells were classified as Y-cells and 72% were classified as W-cells. The Y-cells tended to be located in the magnocellular division of layer C and most (though not all) W-cells were in the parvocellular division. Normal layers C1 and C2 contained almost exclusively W cells. The incidence of Y and W cells was similar to normal in the nondeprived and deprived C-layers of MD cats. 4. In normal cats, W cells typically had the lowest amplitude first-harmonic (F1) response rates to drifting sine-wave gratings. However, many W cells gave quite brisk responses and, overall, there was no significant difference between F1 response amplitudes of Y and W cells. Response amplitudes of Y- and W-cells in the deprived and nondeprived C-layers of MD cats were not significantly different from normal. 5. Normal Y- and W-cells tended to have low optimal spatial frequencies (0.2 c/deg or lower) and spatial resolutions (generally 0.4-1.6 c/deg) to drifting sine-wave gratings.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Effects of bilateral and unilateral ablation of auditory cortex in cats on the unconditioned head orienting response to acoustic stimuli.

1. Reflexive head orienting responses (ORs) elicited by bursts of wide-band noise were investigated in cats after bilateral or unilateral ablation of the auditory cortex, and the cats' performance was compared with that of control cats. The OR was used as an indication of ability to orient toward the azimuthal direction of a source of sound. 2. To adequately test this ability, a unique combination of stimulus duration and position of the sound source was selected on each trial. Stimulus durations (0.1, 0.3, and 1.5 s) were selected so that the offset of a burst of noise occurred before, during, or after an OR. The stimuli were produced from speakers positioned approximately at the interaural horizontal plane within each quadrant of a cat's auditory field. The ORs were recorded on moving film and analyzed quantitatively. 3. In the control cats, the trajectory of the OR was characterized by a saccadic profile (rapid steplike movement, monophasic velocity, and biphasic acceleration). The accuracy of the OR varied directly with stimulus duration, suggesting that the response was modified by auditory feedback produced by a head movement during the stimulus. Corrective responses executed during long-duration (1.5 s) stimuli reduced residual mean error to < 7 degrees in each of the control animals. The mean error in orientation was smaller for sources located in the frontal sound field than for sources located behind the coronal plane the head (> 90 degrees). When brief (0.1 s) stimuli were presented behind the head, the cats confused back with front directions on most of the trials. 4. Compared with performance in the control cats, bilateral destruction of the auditory geniculocortical system severely impaired a cat's ability to orient consistently and accurately toward a source of sound. Latencies to the onset of ORs were increased, the magnitudes of ORs were reduced, average error in orienting to a sound source was larger under every stimulus duration-source position combination, relatively few corrective responses were executed, and residual mean error was significantly elevated (bilateral = 28.1 degrees; control = 3.1 degrees). Several animals with bilateral lesions also made vertical errors in orienting to azimuthal sources of sound. 5. However, in the bilateral lesion group, ORs were initiated in the correct right or left direction; and, rather than eliminating accurate responses altogether, the lesions reduced the probability of their occurrence. Furthermore, the saccadic profile of the response was preserved, providing evidence that the motor control system for the OR was not perturbed by the bilateral lesions.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1995

Alterations of visual climbing fiber response properties in cat cerebellar flocculus after cerebral cortical lesions.

1. In the anesthetized decorticate cat, we recorded complex spike (CS) activity together with concomitant simple spike (SS) activity of the cerebellar flocculus (FL) Purkinje cells that responded to large-field visual pattern movement. The cerebral cortical contributions to the visual response characteristics were investigated by comparing the present results with the previous results of the anesthetized normal cat. 2. The direction-selective characteristics of the CS responses at a low (2 degrees/s) stimulus velocity are well preserved after the decortication. As in the normal cat, the cells are divided into two major types: the horizontal type that prefers horizontal stimuli and the vertical type that prefers vertical stimuli. The CS rate of the former increases during stimuli directed contralaterally to the recording site and decreases during ipsiversive stimuli, whereas that of the latter increases during upward stimuli and decreases during downward stimuli. Reciprocal properties of the CS and SS responses also are preserved: when the CS rate increases, the SS rate decreases and vice versa. 3. For both types, the CS modulation at high stimulus velocities is reduced after the decortication. The half-reduction of the average modulation occurs at approximately 100 degrees/s stimulus velocity compared with the modulation at 2 degrees/s in the normal cat, whereas it occurs at a lower velocity approximately 50 degrees/s in the decorticate cat. 4. For both types, the CS responses usually are driven through either eye in the normal cat. After the decortication, the CS modulation through the contralateral eye is reduced. 5. For both types, the receptive field of the ipsilateral eye extends into both visual hemifields in the normal cat. The CS responses through the contralateral visual hemifield are abolished, whereas those through the ipsilateral visual hemifield are preserved after the decortication. The CS modulation during stimuli restricted within a small central visual field (15 degrees x 15 degrees) projecting to the area centralis is prominent (approximately 70% of the full-screen response) in the normal cat and is sharply reduced (30%) after the decortication.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1996

A comparison of treadmill locomotion in adult cats before and after spinal transection.

1. The aim of this study was to document the kinematics and the electromyographic activity recorded from several muscles during treadmill locomotion in the same cat (N = 4), before and after spinalization by using a chronic implantation method. Because identical experimental and control conditions were used, it was possible to establish similarities and differences in the timing and amplitude of the muscular activity and kinematics under the intact and spinal conditions in the same animal. The data presented in this paper were collected when the cats had fully recuperated a stable locomotor pattern, walking at a constant speed of approximately 0.4 m/s. 2. The adult spinal cats retained many of the general locomotor features and electromyographic (EMG) characteristics seen before transection. However, there were also important differences. 3. There was a reduction in the step length that was principally due to the forward placement of the paw at the onset of the stance. Similarly, there was a decrease in the step cycle duration which was attributed to a reduction of both the stance and swing phases. 4. The overall angular excursions of the hip, knee, and ankle were generally similar, although joints were sometimes more flexed at all phases of the step cycle. In contrast, the overall excursions of the metatarsophalangeal joints was much greater in all four cats after spinalization due to a paw drag during the initial portion of the swing phase that exaggerated the plantarflexion. 5. There was an increase in the EMG amplitude of the flexor muscles at two of three joints (i.e., hip, knee, and ankle) in each cat after spinalization. The change in the EMG amplitude of the extensors did not appear to be as consistent as that observed in the flexor muscles. When looking at each cat individually, the postspinalization extensor activity decreased at two of three joints in two cats, whereas the opposite was true for the other two cats. 6. There was a delay in the onset of the knee flexor (semitendinosus) activity while the ankle dorsiflexor (tibialis anterior) activity started earlier with respect to the beginning of the swing phase. The onset of hip flexors was somewhat more variable. This change in the timing of flexor activity was most probably responsible for the paw drag at the onset of the swing phase. 7. The present results reveal that despite the few differences, the spinal cord and the hindlimbs afferents are capable of generating very good locomotor patterns with almost normal kinematics and EMG characteristics.

Animals↗
PubMed1999

Hindlimb locomotor and postural training modulates glycinergic inhibition in the spinal cord of the adult spinal cat.

Adult spinal cats were trained initially to perform either bipedal hindlimb locomotion on a treadmill or full-weight-bearing hindlimb standing. After 12 wk of training, stepping ability was tested before and after the administration (intraperitoneal) of the glycinergic receptor antagonist, strychnine. Spinal cats that were trained to stand after spinalization had poor locomotor ability as reported previously, but strychnine administration induced full-weight-bearing stepping in their hindlimbs within 30-45 min. In the cats that were trained to step after spinalization, full-weight-bearing stepping occurred and was unaffected by strychnine. Each cat then was retrained to perform the other task for 12 wk and locomotor ability was retested. The spinal cats that were trained initially to stand recovered the ability to step after they received 12 wk of treadmill training and strychnine was no longer effective in facilitating their locomotion. Locomotor ability declined in the spinal cats that were retrained to stand and strychnine restored the ability to step to the levels that were acquired after the step-training period. Based on analyses of hindlimb muscle electromyographic activity patterns and kinematic characteristics, strychnine improved the consistency of the stepping and enhanced the execution of hindlimb flexion during full-weight-bearing step cycles in the spinal cats when they were trained to stand but not when they were trained to step. The present findings provide evidence that 1) the neural circuits that generate full-weight-bearing hindlimb stepping are present in the spinal cord of chronic spinal cats that can and cannot step; however, the ability of these circuits to interpret sensory input to drive stepping is mediated at least in part by glycinergic inhibition; and 2) these spinal circuits adapt to the specific motor task imposed, and that these adaptations may include modifications in the glycinergic pathways that provide inhibition.

Animals↗
PubMed2000

Spontaneously occurring arrhythmogenic right ventricular cardiomyopathy in the domestic cat: A new animal model similar to the human disease.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary myocardial disease of incompletely resolved pathogenesis and is a largely unappreciated cause of sudden death in the young. METHODS AND RESULTS: Clinical features of 12 domestic cats with ARVC (7 male; 1 to 20 years old, mean 7.3+/-5.2 years) were right-sided congestive heart failure (n=8), supraventricular tachyarrhythmias (n=5), ventricular tachycardia (n=3), polymorphic ventricular arrhythmias (n=6), and right bundle-branch block (n=5). ARVC was suspected in all 8 cats examined with echocardiography by marked enlargement of the right ventricle (RV) and right atrium and tricuspid regurgitation. Eight died of cardiovascular disease and 4 died of noncardiac conditions. At autopsy, hearts of ARVC cats were characterized grossly by moderate-to-severe RV cavity enlargement and wall thinning (n=12) and apical aneurysm formation (n=6). Histology demonstrated pronounced RV lesions in all 12 ARVC cats, including marked myocardial injury (myocyte death and atrophy) and repair (fibrous and/or fatty replacement). Injury and repair were also evident in the left ventricle (LV) in 10 cats, and 2 had involvement of both atria. Myocarditis was present in 10 of the 12 ARVC cats. Apoptosis was detected in 9 ARVC cats (mean apoptotic index, 28+/-23% RV, 21+/-19% LV, and 17+/-15% ventricular septum) but not in controls. CONCLUSIONS: In the common domestic cat, we identified a clinically relevant cardiomyopathy that closely mimics ARVC in humans. This unique feline model of human disease will be relevant to defining pathogenesis and investigating mechanisms responsible for disease progression in ARVC.

Animals↗
PubMed1991

Coronary microvascular resistance in hypertensive cats.

Chronic systemic hypertension has been shown to alter the distribution of vascular resistance in many microvascular beds. The purposes of this study were to assess the effects of chronic systemic hypertension on the pressure distribution in the coronary microcirculation and to determine the microvascular site where coronary vascular resistance is increased. Cats were made hypertensive using a one-kidney, one-wrap model (Page model). A servonulling system was used to directly measure pressures in the epimyocardial microvessels of the beating left ventricle in normotensive and hypertensive cats. In chronically hypertensive cats, mean arterial pressure was 153 +/- 5 mm Hg compared with 98 +/- 3 mm Hg in normotensive cats (p less than 0.05). Left ventricular mass was increased approximately 34% in hypertensive cats (9.4 +/- 0.3 versus 7.0 +/- 0.3 g, p less than 0.05). Myocardial perfusion measured using radiolabeled microspheres was not different between hypertensive and normal cats. Coronary vascular resistance of the left ventricle was increased in hypertensive cats (0.90 +/- 0.08 versus 0.66 +/- 0.05 mm Hg x min x 100 g/ml, p less than 0.05). Microvascular pressures were measured in three groups of microvessels: small, less than 200 microns; medium, 200-300 microns; and large, greater than or equal to 300 microns. Mean microvascular pressures of large, medium, and small arterial microvessels in hypertensive cats were 144 +/- 8, 127 +/- 6, and 115 +/- 7 mm Hg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗