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Biomedical subjects

A J Venker-van Haagen

Publications and source records attributed to A J Venker-van Haagen.

At least 19 recordsLinked to original sources
PubMed2000

The rat vertex-middle latency auditory-evoked potential as indicator of anaesthetic depth: a comparison with evoked-reflex testing.

We investigated whether components from the rat Vx-MLAEP could be used to assess depth of anaesthesia induced by propofol. Propofol decreased MLAEP amplitudes and increased latencies. We propose that the P(16)-N(22) wave in the rat MLAEP is similar to the human P1, and that recovery of this wave during propofol anaesthesia correlates with behavioural measures of the regaining of consciousness.

Anesthesia↗
PubMed1999

Effect of superior laryngeal nerve transection on pharyngeal muscle contraction timing and sequence of activity during eating and stimulation of the nucleus solitarius in dogs.

The effect of unilateral or bilateral transection of the superior laryngeal nerve on the electromyographic activity in the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles was studied in 10 dogs during eating and during unilateral electrical stimulation of the solitary nucleus. In all groups of dogs, after unilateral or bilateral transection, there were some swallowing actions in which the sequence of activity in the pharyngeal muscles was disturbed during eating and during stimulation of the solitary nucleus. In the dogs in which the transection was unilateral, this fraction was 18% in the ipsilateral muscles during eating and 7% in the contralateral muscles. After bilateral transection it was 8% in the left muscles and 16% in the right muscles. The fractions were not significantly different when swallowing was evoked by stimulation of the solitary nucleus. Swallowing actions having a normal sequence of activity in these dogs were compared with those in a group of eight dogs in which the superior laryngeal nerves were intact. Contraction timing was not significantly different during eating, but during stimulation of the solitary nucleus the timing was significantly shorter than in the dogs with intact nerves. It was concluded that superior laryngeal nerve transection modulates the central pattern generator for pharyngeal swallowing in dogs.

Animals↗
PubMed1999

Functional anatomy and neural regulation of the lower urinary tract in female dogs: a review.

A review of the literature of the functional anatomy and neural regulation of the lower urinary tract is presented. The two main functions of the lower urinary tract are the storage and the periodic elimination of urine. The smooth muscle of the bladder exhibits intermittent contractions as the bladder adapts its capacity to increasing volumes and it exhibits sustained contractions associated with relaxation of the external sphincter to effect micturition. During storage, tension receptors in the bladder wall initiate external sphincter contraction (somatic), internal sphincter contraction (sympathetic), detrusor inhibition, and parasympathetic ganglion inhibition (sympathetic). The storage phase can be switched to the micturition phase either voluntarily or involuntarily. Neuroanatomical and electrophysiological studies reveal that medial and lateral cell groups in the dorsolateral pons may be regarded as micturition and storage control centres, respectively.

Animals↗
PubMed1999

Evidence for recurrent laryngeal nerve contribution in motor innervation of the human cricopharyngeal muscle.

OBJECTIVE: To study the functional motor nerve supply of the upper esophageal sphincter in humans. STUDY DESIGN: Intraoperative electromyographic study. METHODS: The contribution of the recurrent laryngeal nerve and the pharyngeal plexus in the motor nerve innervation of the cricopharyngeal muscle and the inferior pharyngeal constrictor muscle was examined intraoperatively. RESULTS: Electromyography showed that there is a considerable overlap in the innervation of the cricopharyngeal muscle and the inferior pharyngeal constrictor muscle. The recurrent laryngeal nerve functionally contributes to the motor innervation of the cricopharyngeal muscle in all patients and contributes to the motor innervation of the inferior pharyngeal constrictor muscle in most patients. The pharyngeal plexus functionally contributes to the motor innervation of the inferior pharyngeal constrictor muscle but does not always contribute to the motor innervation of the cricopharyngeal muscle. CONCLUSIONS: This is the first report which provides evidence that the recurrent laryngeal nerve functionally contributes to the motor innervation of the cricopharyngeal and inferior pharyngeal constrictor muscle. Furthermore, this study shows that intraoperative electromyography in humans is a feasible method to analyze the physiology of the motor innervation of the upper esophageal sphincter.

Adult↗
PubMed1999

EEG evaluation of reflex testing as assessment of depth of pentobarbital anaesthesia in the rat.

Electroencephalography (EEG) was applied to evaluate the validity of the paw pinch reflex as an indicator of anaesthetic depth in rats which are anaesthetized with a single intraperitoneal dose of pentobarbital. After induction of the anaesthesia, characterized by the rapid loss of the animals' ability to maintain upright posture, the EEG of 10 out of 11 rats was dominated by paroxysmal (burst suppression) activity, associated with unconsciousness. In seven out of 11 rats, the paw pinch reflex was lost after onset of paroxysmal electroencephalographic activity. However, the paw pinch reflex remained present in four out of 11 animals, demonstrating that the response is independent of cortical activity. In five out of seven rats, the EEG still showed paroxysmal activity when the paw pinch reflex was regained. However, in two other rats the EEG returned to a pattern similar to that shown by awake animals, 4 and 21 min respectively, before the reflex was regained. These data indicate that in the pentobarbital-anaesthetized rat, presence of the paw pinch reflex is not related to the level of depression of electrical activity in the cerebral cortex, and consequently is probably not related to the level of consciousness. Based upon these findings it is concluded that the paw pinch reflex is unreliable as a sole indicator of anaesthetic depth.

Analgesics, Opioid↗
PubMed1998

Effect of stimulating peripheral and central neural pathways on pharyngeal muscle contraction timing during swallowing in dogs.

The effect of stimulating peripheral and central neural pathways on the electromyographic activity in the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles was studied in eight dogs during 1) eating, 2) unilateral electrical stimulation of the superior laryngeal nerve, and 3) unilateral electrical stimulation of the solitary nucleus. The duration of pharyngeal swallowing was significantly shorter during eating than during stimulation of the solitary nucleus in the anesthetized dog (mean difference 127 ms, SEM 9, n = 15). The duration of pharyngeal swallowing was significantly shorter during eating than during stimulation of the superior laryngeal nerve in the awake dog (mean difference 84 ms, SEM 13, n = 9). The duration of pharyngeal swallowing during stimulation of the superior laryngeal nerve under anesthesia was significantly shorter than during stimulation of the solitary nucleus under anesthesia (mean difference 58 ms, SEM 18, n = 9). The difference in duration of pharyngeal swallowing during stimulation of the superior laryngeal nerve between the awake state and during anesthesia was not significant (mean 19 ms, SEM 14, n = 9). It was concluded that stimulation of peripheral and central neural pathways resulted in different pharyngeal muscle contraction timing during swallowing in dogs.

Animals↗
PubMed1997

Comparison of air- and bone-conducted brain stem auditory evoked responses in young dogs and dogs with bilateral ear canal obstruction.

Brain stem responses to air- and bone-conducted stimuli were analyzed in 11 young dogs, using an in-the-ear transducer and a vibrator designed for human hearing tests, respectively. The mean thresholds were 0 to 10 dB for air-conducted stimuli and 50 to 60 dB for bone-conducted stimuli. The wave forms and inter-peak latencies of the waves of the auditory evoked responses elicited by air-conducted and bone-conducted stimuli were similar. This indicated that the signals had the same origin and thus both the air-conducted and the bone-conducted responses could be considered to be auditory responses. Measurement of air-conducted and bone-conducted brain stem-evoked responses in five dogs with bilateral chronic obstructive ear disease revealed thresholds of 50 to 60 dB for air-conducted stimuli and 60 to 70 dB for bone-conducted stimuli. By comparison of these results with those in the 11 young dogs, it could be concluded that there was hearing loss other than that caused by obstruction of the ear canals.

Aging↗
PubMed1996

Immunoglobulin concentrations in nasal lavage fluids in dogs with non-specific rhinitis.

The pathophysiology of non-specific chronic rhinitis(NSCR) in dogs is still unknown. In this study the possible role of immunological mechanisms in NSCR is examined, by comparing immunoglobulin concentrations in nasal lavage fluids of dogs with NSCR with those of healthy dogs. The immunoglobulin IgA was detected in nasal lavage fluids of both groups of dogs and the differences in relative levels of IgA in dogs with NSCR were not significant. IgM, IgG(a,b), and IgG(d) were detected more frequently in dogs with NSCR (P<0.05), and the relative levels were higher. The presence of IgG(a,b) may indicate the chronic character of rhinitis, and the presence of IgG(d) the possibility of an allergic component in its pathophysiology. The role of IgM is not completely clear.

Animals↗
PubMed1995

CMAPs in pharyngeal and hyoid muscles evoked by nucleus solitarius stimulation in dogs.

Electrical stimulation of the solitary nucleus with a single pulse of 150 to 500 microA caused visible contractions of the muscles involved in swallowing but did not activate the central pattern generator for swallowing. Electromyographically there were short bursts of activity characterized by an onset of activity within 1 to 7 ms, a duration of 14 to 26 ms, and an amplitude of 10 to 4,800 microV. The CMAPs were recorded in the pharyngeal and hyoid muscles on both the ipsilateral and the contralateral sides of the stimulated solitary nucleus. Across all five pairs of muscles in which the recordings were made the latencies of the CMAPs in the contralateral muscles were significantly greater and the amplitudes significantly lower, but the durations were not significantly different. Bilateral activation of the muscles by unilateral stimulation may not result in symmetrical contraction of the pharyngeal muscles.

Action Potentials↗
PubMed1995

Comparison of volume-conducted far-field short-latency glossopharyngeal nerve evoked potentials recorded from the scalp with similarly obtained near-field potentials from the solitary nucleus in dogs.

In 11 dogs, potentials recorded from the scalp and from the solitary nucleus after stimulation of the glossopharyngeal nerve were compared. The far-field potentials recorded from the scalp consisted of negativity, with peak latency of 2.10 to 3.45 milliseconds (mean, 2.93 milliseconds), followed by positivity, with peak latency of 3.20 to 5.95 milliseconds (mean, 4.86 milliseconds) and duration of 4.65 to 6.95 milliseconds (mean, 5.70 milliseconds). The near-field potentials recorded from the solitary nucleus consisted of positivity, with peak latency of 2.15 to 2.70 milliseconds (mean, 2.45 milliseconds), followed by negativity, with peak latency of 4.05 to 5.05 milliseconds (mean, 4.39 milliseconds) and duration of 4.45 to 5.80 milliseconds (mean, 5.21 milliseconds). Comparison of the far-field potentials (n = 10) with the near-field potentials (n = 5) indicated that polarity of the waves was reversed and that the first peak's latency was slightly (approx 0.5 milliseconds) longer in the scalp-recorded far-field potentials. Neither the difference in latency of the second peak nor the difference in its duration, measured from the onset of the potentials to the return to the baseline of the activity, was significant. The results strongly suggest that the response in the solitary nucleus evoked by electrical stimulation of the glossopharyngeal nerve is the source of at least part of the scalp-recorded responses to stimulation of the same nerve. The scalp-recorded far-field potentials could, therefore, be characterized as volume conducted from the evoked response in the solitary nucleus.

Animals↗
PubMed1993

Evaluation of a standardised questionnaire for the detection of dysphagia in 69 dogs.

The diagnosis of dysphagia in the dog requires an evaluation of a variety of signs that can be caused not only by a 'swallowing disorder' but also by several other pathological conditions. Most owners mention coughing, vomiting, regurgitation and nasal discharge, and the clinician must decide whether these signs are related to dysphagia. In this study a standardised questionnaire for the diagnosis and localisation of dysphagia was evaluated for its accuracy by comparing the results with contrast videofluorography as the definitive standard. The purpose of the study was to optimise the selection of dogs for more expensive diagnostic procedures such as videofluorography and electromyography. In a group of 69 dogs with 'swallowing problems' the questionnaire had a sensitivity of 0.97 and a positive predictive value of 0.94 for dysphagia in general. The questionnaire was also useful for the exclusion of oral phase dysphagia, with a specificity of 0.70 and a negative predictive value of 0.97. Most dogs with pharyngeal phase dysphagia could be detected by using the questionnaire (sensitivity 0.91). The questionnaire was not of specific value for the detection or exclusion of oesophageal phase dysphagia, for which it had a sensitivity of 0.69, a specificity of 0.57 and predictive values for positive and negative tests of 0.79 and 0.44, respectively.

Animals↗