Search PubMed⌕ Search

Biomedical subjects

M H Sims

Publications and source records attributed to M H Sims.

At least 19 recordsLinked to original sources
PubMed1994

Iloprost reduces leukocyte adhesion in skeletal muscle venules following ischaemia in a rat model of femorodistal bypass.

UNLABELLED: Intraarterial bolus treatment with the prostacyclin analogue iloprost appears to have a prolonged beneficial effect on femorodistal bypass graft flow which extends beyond the duration of its vasodilator properties. The effect of iloprost on the microcirculation rendered ischaemic over the time course of a distal bypass operation was investigated in this study without the use of fluorescent light. METHODS: A rat model was designed to allow prolonged direct observation of leukocyte-venular endothelial adhesion in a femorodistal bypass simulation. The extensor digitorum longus (EDL) muscle of 10 rats was subjected to two 30 minute periods of ischaemia by a non-venous occluding tourniquet and to simulate some of the changes of chronic ischaemia the adverse effect of ischaemia was accentuated by indirect electrical stimulation via the lateral popliteal nerve. RESULTS: Intraarterial bolus treatment with iloprost significantly reduced the total numbers of leukocytes observed in EDL venules, and the numbers exhibiting evidence of adhesion by rolling or sticking to venule endothelium compared with saline controls at one hour post ischaemia. Ischaemia induced vasodilatation and reduced shear stress by a similar and significant amount in both groups. CONCLUSION: Two periods of ischaemia and reperfusion similar to those which occur during bypass grafting resulted in changes in the distal microcirculation consistent with reperfusion injury. Intraarterial bolus treatment with iloprost prevented these leucocyte-endothelial changes. It appears iloprost may have a role in reducing leukocyte-induced reperfusion injury in femorodistal bypass surgery.

Animals↗
PubMed1993

Effect of total ablation of the external acoustic meatus and bulla osteotomy on auditory function in dogs.

Seven dogs with end-stage bilateral otitis externa were evaluated for auditory function before and after bilateral total ear canal ablation and lateral bulla osteotomy. Evaluations were performed by owner questionnaire and by recording brainstem auditory-evoked responses. Prior to surgery, all dogs could hear a loud voice or noise, however, only 3 dogs responded to a voice spoken at a normal level. Of the 14 ears tested electrodiagnostically, only 1 did not have a response, using air-conducted or bone-conducted stimuli. After surgery, 2 dogs responded to a normal voice, but all 7 responded to loud voices or noise. Three ears that had recordable brainstem auditory-evoked responses to air-conducted stimulation prior to surgery, failed to respond after surgery. Ears that responded to bone-conducted stimulation prior to surgery also responded after surgery.

Animals↗
PubMed1991

Otoacoustic emission in a dog.

A 7-month-old female Poodle was evaluated for a sound continuously emanating from its left ear. The frequency and intensity of the tone was matched by use of a multifrequency audiometer. The frequency and intensity of the sound were 9,594 Hz and 45.5 decibels sound pressure level, respectively. On the bases of normal brain stem auditory-evoked responses and behavioral response to sound, the dog was believed to have normal hearing in both ears. Emission of sound from an ear, referred to as an otoacoustic emission, is a condition that has been reported in human beings and small animals. Successful treatment in human patients with drugs and masking sounds is difficult, and treatment has not been reported in animals. This condition in dogs is not considered life-threatening.

Animals↗
PubMed1991

Use of fine-wire electrodes for electromyographic evaluation of the external urethral sphincter during urethral pressure profilometry in male cats.

Evaluation of urethral pressure profilometry (UPP) with simultaneous fine-wire electromyography of the external urethral sphincter (EUS) was conducted in 11 healthy adult male cats sedated with xylazine and ketamine. A 3.5-F urethral catheter with a closed end and two 1-mm side-ports was infused with sterile 0.9% NaCl solution at a rate of 2 to 3 ml/min. A fine-wire electromyographic (EMG) electrode was placed percutaneously into or near the external urethral sphincter prior to the onset of the UPP. The maximal urethral pressure achieved and functional profile length were recorded from UPP. Setting both catheter withdrawal rate and paper speed at 5 mm/s enabled the measurement of actual urethral length directly from UPP. Sphincter EMG activity was rated as slight (+), moderate (+ +), or intense (+ + +). All recordings were replicated once during each trial for 8 cats and trials were replicated 5 to 7 days later in 4 cats. Before catheterization, EMG activity of the external urethral sphincter was rated slight (+), whereas intense (+ + +) activity accompanied insertion. The activity evoked by movement of the catheter subsided, but intense EMG activity of the external urethral sphincter was recorded from onset to completion of catheter withdrawal in all cats in both trials. The mean maximal urethral pressure was 93.1 +/- 13.29 cm H2O. The mean function urethral length was 8.1 +/- 0.93 cm. Maximal urethral pressure or function profile length did not differ significantly between recordings within trials or between trials. Simultaneous recording of EMG activity and UPP of the external urethral sphincter was shown to be a simple, noninvasive technique for assessing neuromuscular and anatomic urethral function.

Animals↗
PubMed1990

Changes in oscillatory potentials in the canine electroretinogram during dark adaptation.

Oscillatory potentials (OP) and electroretinograms (ERG) were recorded from clinically normal dogs after 5, 10, 15, 20, 30, 40, 50, and 60 minutes of dark adaptation. At the end of the adaptation period, OP were characterized by 5 distinct positive peaks, O1 through O5, with mean latencies of 14.46, 20.24, 27.38, 35.31, and 44.85 ms, respectively, and with mean amplitudes ranging from 7.20 to 34.84 microV. After 60 minutes of dark adaptation, the ERG had a mean a-wave latency of 12.03 ms and a mean b-wave amplitude of 109.29 microV. Peaks O3 and O4, which partially mask the summit of the b-wave, had mean latencies of 28.66 and 36.83 ms, respectively. The mean amplitude of the b-wave measured to the peak of O3 was 240.06 microV and 230.73 microV when measured to peak O4. Changes in the OP during dark adaptation consisted of significant (P less than 0.05) increases in the latencies of O1, O2, and O3, and significant increases in the amplitudes of O1, O3, O4, and O5. Concurrent ERG changes consisted of significant increases in the amplitudes of the a-wave and b-wave measured from O3 and O4, and significant increases in the latencies of peaks O3 and O4 on the b-wave.

Animals↗
PubMed1990

Electromyographic evaluation of the external urethral sphincter during cystometry in male cats.

Electromyographic (EMG) evaluation of the external urethral sphincter (EUS) was conducted during cystometry in 11 adult male cats sedated with xylazine and ketamine. A percutaneously placed antepubic catheter was used for bladder infusion and recording intravesicular pressures during cystometrography (CMG). A fine-wire electrode was placed percutaneously into or near the EUS for recording EMG during CMG. The bladder was infused with sterile 0.9% NaCl solution at a rate of 2 to 3 ml/min until a detrusor reflex was initiated. Intravesicular pressures at the onset of infusion, immediately prior to micturition, at the onset of urine flow, and at the maximal voiding pressure were recorded. The time from infusion to micturition, from opening pressure to return to baseline, and from the beginning to the end of the CMG were also recorded. The total volume of 0.9% NaCl solution infused and the residual bladder volume after micturition were also measured. Recordings were replicated once during each trial in all cats, and trials were replicated once approximately 1 week later in 4 cats. Micturition patterns were characterized by slight to moderate EUS EMG activity during vesicular filling, with reduction in activity during emptying. Maximal EMG activity was recorded at the completion of the reflex and was associated with pulsatile expulsion of small amounts of urine. The simultaneous recording of CMG and EUS EMG with fine-wire electrodes was simple and reliable for assessing the neuromuscular integrity and synchrony of detrusor and EUS muscles. There were no significant differences in variables between recordings within trial 1, but there were differences (P less than or equal to 0.05) between trials for pressure at the onset of urine flow and maximal voiding pressure.

Animals↗
PubMed1989

Waveform analysis and reproducibility of visual-evoked potentials in dogs.

Visual-evoked potentials (VEP) and electroretinograms (ERG) were recorded from 10 normal light-adapted adult dogs, using a 3 x 5 matrix of light-emitting diodes as a stimulator. Visual-evoked potentials were recorded from 4 scalp electrodes overlying cortical areas, whereas electroretinographic activity was recorded by 2 scalp electrodes placed near the eye and by a conjunctivally placed electrode. The waveform of the VEP consisted of 3 major positive waves (P1 through P3), with peak latencies in the 20- to 70-ms range. Waveform reproducibility was assessed by comparing peak latencies from VEP recorded on 2 separate days approximately 1 week apart. The peak latencies for P1 through P3 did not differ (P greater than or equal to 0.05) between first and second recording sessions. To substantiate the postretinal origin of VEP, recordings were made before and after unilateral optic nerve transsections in 4 dogs. Electroretinograms were also measured before and after surgery to assess the integrity of the retina. Postsurgically, VEP were absent when the eye on the surgically treated side was stimulated. Stimulation of the contralateral eye induced VEP with the same waveform shape, but latencies were slightly prolonged (P less than or equal to 0.05) compared with presurgical recordings. The only effect of optic nerve transsection on the ipsilateral ERG was a prolongation (P less than or equal to 0.05) of the b-wave. However, when postsurgical ERG values were compared with those from the intact side after surgery, there were no differences.

Animals↗
PubMed1989

Somatosensory-evoked and spinal cord-evoked potentials in response to pudendal and tibial nerve stimulation in cats.

Somatosensory-evoked potentials (SEP) and spinal cord-evoked potentials (SCEP) were recorded in clinically normal adult cats in response to electrical stimulation of pudendal and tibial nerves to provide normative data that can be used in a clinical evaluation of pudendal nerve function in cats after sacral or sacrococcygeal luxations or fractures. Responses to tibial nerve stimulation were included in the study as an internal control because it is usually not involved in these types of injuries and because its SEP and SCEP are easily recorded. Evoked potentials were characterized by the latencies (ms) of positive (P or p) and negative (N or n) peaks. The SEP resulting from percutaneous pudendal nerve stimulation consisted of a prominent P-N-P potential in the 30- to 80-ms range. The pudendal SCEP was not successfully recorded because of large muscle artifacts evoked from the sacral area. The tibial SEP was similar to the pudendal SEP, except that the prominent P-N-P series in the 35- to 81-ms range was preceded by a smaller p-n-p-n sequence in the 7- to 23-ms range. The tibial SCEP consisted of a P-N-P series in the 2- to 4-ms range.

Animals↗
PubMed1988

Visual-evoked potentials in cats, using a light-emitting diode stimulator.

Visual-evoked potentials (VEP) were studied in 8 healthy adult cats anesthetized with xylazine HCl and ketamine HCl. Monocular visual stimulation was accomplished by a 3 x 5 matrix of light-emitting diodes. Subcutaneous needle electrodes placed in the scalp at various locations and a contact lens electrode on the cornea were used to record cortical and electroretinographic activities, respectively. Multiple electrode pairings and unilateral optic nerve transsection were used to distinguish between retinal and postretinal potentials recorded from scalp electrodes. The VEP was a robust polyphasic cortical potential, with peak latencies between 0 and 110 ms. Using the light-emitting diode method of stimulation, a VEP was recorded which was not contaminated by volume-conducted retinal activity.

Animals↗
PubMed1986

Fiber type composition of rostral and caudal portions of the digastric muscle in the dog.

The distribution of muscle fiber types in rostral and caudal portions of the musculus digastricus (digastric muscle) was studied in 6 dogs. Staining procedures which stain specifically for type IIM fibers, a fiber type found in other muscles supplied by the trigeminal nerve, were used. Rostral and caudal portions of the muscle were compared because the rostral portion is innervated by the trigeminal nerve, and the caudal portion is innervated by the facial nerve. The musculus triceps brachii (triceps muscle), which contains fiber types I and IIA, and the musculus masseter (masseter muscle), which contains type IIM, were used as controls. Mean fiber diameters were calculated for each of the muscles. Both portions of the digastric muscle exhibited the same histochemical behavior, possessing types I and IIA myofibers. Neither portion contained type IIM fibers. Type I fibers in the masseter muscle were histochemically different from type I fibers in the other muscles studied. Type II fibers predominated in all 3 muscles, but there were significantly (P less than 0.001) more type I fibers in the triceps muscle than in either portion of the digastric muscle or in the masseter muscle. Type II fibers were significantly larger than type I fibers in the caudal digastric (P less than 0.01) and masseter (P less than 0.05) muscles. There was no difference in the size of type I or type II fibers between any of the muscles studied (P greater than 0.20).

Adenosine Triphosphatases↗
PubMed1986

Effects of tenotomy of the tensor tympani muscle on the acoustic reflex in dogs.

The acoustic reflex (AR) was recorded from 12 healthy mixed-breed dogs. Latency and amplitude were measured from ipsilateral and contralateral AR at stimulus frequencies of 1 and 2 kHz and intensities of 70 to 110 dB sound pressure level for ipsilateral AR and 70 to 120 dB hearing level for contralateral AR. Mean latencies for ipsilateral and contralateral AR were between 33.46 and 206.10 ms and between 45.26 and 180.89 ms, respectively, and amplitudes were between 0.14 and 1.79 cm3 and between 0.31 and 1.86 cm3 of air, respectively. Stimulus frequencies and intensities had significant effects (P less than 0.05) on ipsilateral and contralateral AR latencies and amplitudes. Ipsilateral and contralateral AR decays were determined by measuring compliance change during a 10-s pure-tone stimulation at frequencies of 1 and 2 kHz at an intensity of 10 dB above AR threshold. Reflex decays for 1 kHz and 2 kHz frequencies averaged 5.74% and 9.71%, respectively, for ipsilateral AR and 5.08% and 5.40%, respectively, for contralateral AR. Bilateral tympanograms and brain stem auditory-evoked responses were performed on each dog. Mean normal static compliance of the middle ear, as determined by tympanometry, was 0.15 cm3. Unilateral tenotomy of the tensor tympani muscle was done on 6 of the 12 dogs, and each of the preceding procedures were repeated within 1 week after surgical operation. Transection of the tensor tympani tendon did not alter (P greater than 0.05) the latencies or amplitudes of 1 kHz- or 2 kHz-evoked contralateral AR, the latency or amplitude of 1 kHz-evoked ipsilateral AR, or the amplitude of 2 kHz-evoked ipsilateral AR. However, the latency of 2 kHz-evoked ipsilateral AR was significantly (P less than 0.05) increased. Reflex decay increased significantly (P less than or equal to 0.001) for the contralateral reflex elicited by the 2 kHz stimulus. Neither compliance of the middle ear system nor amplitude and latency of the brain stem auditory-evoked response were affected (P greater than 0.05) by tenotomy. Since tenotomy eliminates participation of the tensor tympani in the AR, these data indicate that contraction of this muscle is not primarily responsible for the compliance changes recorded during an acoustic reflex in dogs.

Animals↗
PubMed1986

Effects of xylazine and ketamine on the acoustic reflex and brain stem auditory-evoked response in the cat.

The acoustic reflex (AR) and brain stem auditory-evoked response (BAER) were recorded in adult cats 5 minutes after IM administration of xylazine (1 mg/kg) and after IM administration of ketamine (10 mg/kg). Ipsilateral and contralateral AR were recorded at 10 and 20 dB above acoustic reflex threshold 5 minutes after xylazine administration and 5 and 35 minutes after ketamine administration. Monaural BAER were recorded 5 minutes after xylazine and 5 and 35 minutes after ketamine, using stimulus intensities of 90-, 80-, and 70-dB hearing level (HL). Additional BAER were recorded at 10, 15, and 25 minutes after ketamine, using the 90-dB HL stimulus. Pre- and postinjection comparisons were made for threshold, latency, and amplitude of the AR and for latency and amplitude of waves I through VI of the BAER. At both stimulus intensities before and after ketamine administration threshold for the ipsilateral reflex was significantly lower (P greater than 0.05) than for the contralateral reflex. The threshold, latency, and amplitude of the AR were unaffected (P greater than 0.05) by the injection of ketamine after xylazine. The amplitude of BAER waves was not affected (P greater than 0.05) by ketamine after xylazine for each of the 3 stimulus intensities. Latency of the 90-dB HL-evoked response was increased (P less than or equal to 0.05) for waves III/IV at 5 and 35 minutes after ketamine, and for wave V at each of the postinjection times, except at postinjection minute 15.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Electrodiagnostic evaluation of deafness in two English setter littermates.

Two English Setter littermates (male and female) were evaluated for hearing difficulties at 4, 16, and 24 months of age. Auditory function was evaluated by behavioral response to pure-tone sounds, tympanometry, brain stem auditory evoked response, and acoustic reflex testing. Hereditary sensorineural deafness was diagnosed in both dogs. The extent of the hearing deficit, as characterized by these tests, was slightly different between the dogs, as well as between the ears in 1 dog.

Acoustic Impedance Tests↗
PubMed1984

Changes in plasma, red blood cell and cerebrospinal fluid mineral concentrations in calves during magnesium depletion followed by repletion with rectally infused magnesium chloride.

Hypomagnesemic and normomagnesemic calves were infused rectally with MgCl2 X 6H2O to determine effects on magnesium (Mg), calcium (Ca) and potassium (K) concentrations in plasma, red blood cells (RBC) and cerebrospinal fluid (CSF). Sixteen Holstein bull calves were fed one of four semipurified diets containing low or adequate Mg and normal or excess K in a 2 X 2 factorial arrangement. When CSF Mg concentration began to decrease in calves fed low Mg diets, each calf was given a rectal infusion of 50 ml of 30% MgCl2 X 6H2O solution while under general anesthesia. Blood and CSF were then sampled periodically for 3 hours and plasma, RBC and CSF were analyzed for Mg, Ca and K concentration. Plasma Mg increased (P less than 0.001) within 5 minutes after rectal infusion in all calves regardless of diet. An increase (P less than 0.01) in CSF Mg was also observed within 30 minutes in hypomagnesemic calves with CSF Mg levels less than 1.8 mg/dl. Rectal infusions had no effect on K in plasma, Ca or K in CSF, Mg, Ca or K in RBC, or packed cell volume but plasma Ca had increased (P less than 0.05) within 120 minutes in calves fed low Mg and high K and within 60 minutes in those fed adequate Mg, normal K diets.

Animals↗
PubMed1984

Auditory-evoked response in the clinically normal dog: early latency components.

Early latency components (0 to 10 ms) of the auditory-evoked response, which is also called the brainstem auditory-evoked response (BAER), were recorded in 6 clinically normal adult dogs. Each dog responded to suprathreshold monaural clicks with a highly repeatable averaged waveform configuration consisting of 6 to 7 vertex positive waves. Configuration of the canine BAER consisted mainly of waves I, II, III, V, and VI. Wave IV was present in some records, but in most cases, it formed a complex with wave III and was not apparent as a separate wave. After a 90-dB hearing level (HL) stimulus (20/s), the positive peak of wave I in the averaged response appeared at approximately 1 ms after stimulation onset, and subsequent waves were spaced at approximately less than or equal to 1-ms intervals. Amplitudes of these waves were 4.0 microV when measured from positive peak to the following negative trough. Experiments were conducted to determine the effects of varying stimulus intensity (50- to 90-dB HL) on BAER wave amplitude and peak latency in nonanesthetized and anesthetized dogs and to determine the effects of increasing stimulus rate (10 to 50/s) in nonanesthetized dogs. As stimulus intensity was increased in 10-dB steps from 50 to 90 dB and as the stimulus rate remained at 20/s, amplitude increased and latency decreased for all waves (P less than 0.01). When stimulus intensity was held constant at 90 dB and stimulus rate increased from 5 to 50/s, amplitude decreased and latency increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1984

Auditory-evoked response in the clinically normal dog: middle latency components.

The middle latency components (6 to 60 ms) of the auditory-evoked response were recorded in clinically normal mature dogs (n = 15 mixed breed). To record the middle latency response (MLR), a series of suprathreshold auditory clicks was presented monaurally to nonanesthetized and anesthetized dogs at a stimulus rate of 5/s. To determine effects of stimulus intensity on wave amplitude and latency in nonanesthetized dogs, clicks were presented at 90-, 70-, and 50-dB hearing level. Filtered electroencephalic activity during the first 100 ms after each click was recorded and averaged digitally for 1,024 consecutive stimuli. The response pattern in the nonanesthetized dog was a repeatable polyphasic configuration characterized by 3 to 4 major waves. Peaks of the waves were labeled, using a method developed in human beings. Mean latency ranges for the positive (P) or negative (N) peaks that comprised the waves across intensity levels were 7.43 to 7.77 ms (No), 11.07 to 11.57 ms (Po), 13.62 to 14.20 ms (Na), 20.04 to 20.68 (Pa), 39.08 to 39.37 ms (Nb), and 54.25 to 55.21 ms (Pb). The only variations in waveform morphologic features were the additional wave formed by peaks Nx (24.80 to 25.94 ms) and Px (30.0 to 30.62 ms), which occurred in 44% of the records, and the missing wave formed by No and Po in 6.6% of the records. Varying the stimulus intensity had no effect (P less than 0.05) on wave amplitude or latency.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗