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Biomedical subjects

G M Strain

Publications and source records attributed to G M Strain.

At least 19 recordsLinked to original sources
PubMed2000

Effect of hyperbaric oxygen treatment on incorporation of an autogenous cancellous bone graft in a nonunion diaphyseal ulnar defect in cats.

OBJECTIVE: To determine whether hyperbaric oxygen treatment (HBOT) would affect incorporation of an autogenous cancellous bone graft in diaphyseal ulnar defects in cats. ANIMALS: 12 mature cats. PROCEDURE: Bilateral nonunion diaphyseal ulnar defects were created in each cat. An autogenous cancellous bone graft was implanted in 1 ulnar defect in each cat, with the contralateral ulnar defect serving as a nongrafted specimen. Six cats were treated by use of hyperbaric oxygen at 2 atmospheres absolute for 90 minutes once daily for 14 days, and 6 cats were not treated (control group). Bone labeling was performed, using fluorochrome markers. Cats were euthanatized 5 weeks after implanting, and barium sulfate was infused to evaluate vascularization of grafts. Ulnas were evaluated by use of radiography, microangiography, histologic examination, and histomorphometric examination. RESULTS: Radiographic scores did not differ between treatment groups. Microangiographic appearance of grafted defects was similar between groups, with all having adequate vascularization. Differences were not observed between treated and nontreated groups in the overall histologic appearance of decalcified samples of tissue in grafted defects. Mean distance between fluorescent labels was significantly greater in cats given HBOT than in nontreated cats. Median percentage of bone formation in grafted defects was significantly greater in cats given HBOT. CONCLUSIONS: Hyperbaric oxygen treatment increased the distance between fluorescent labels and percentage of bone formation when incorporating autogenous cancellous bone grafts in induced nonunion diaphyseal ulnar defects in cats, but HBOT did not affect revascularization, radiographic appearance, or qualitative histologic appearance of the grafts.

Animals↗
PubMed1999

Congenital deafness and its recognition.

Congenital deafness in dogs and cats is primarily of the hereditary sensorineural form associated with white pigmentation genes, although acquired forms of deafness are possible. Highest prevalence is seen in white cats, especially those with blue eyes, and the Dalmatian, with many other dog breeds affected to some extent. This deafness results from degeneration of the cochlear blood supply at age 3-4 weeks, presumably resulting from suppression of melanocytes by the white (cat) or merle or piebald (dog) genes. Mechanism of inheritance is not understood for most breeds. Such animals should not be bred and may present liabilities for their owners. Objective diagnosis of deafness, especially when unilateral, relies on the brainstem auditory evoked response, an electrodiagnostic test where electrical activity in response to a click stimulus is recorded from the scalp using needle electrodes and a special purpose computer. Client counseling guidelines are presented.

Animals↗
PubMed1998

Autonomic regulation of gastric ulcerogenesis after cervical cord transection in the rat.

OBJECTIVE: To examine the role of anticholinergic and sympathomimetic drugs in preventing gastric ulcerogenesis after cervical cord transection (CCT) in the rat. METHODS: A randomized, prospective, interventional trial was performed comparing pirenzepine (muscarinic type I receptor antagonist) and ephedrine (nonspecific sympathomimetic) in the prevention of gastric ulcerogenesis after CCT in the rat. After isoflurane-induced general anesthesia, group 1 (n = 12) received sham CCT with no pretreatment, group 2 received CCT with no pretreatment, group 3 received CCT with pirenzepine pretreatment (0.01/mg/kg IP), and group 4 received CCT with ephedrine pretreatment (3 mg/kg IP). Six hours after intervention, all the rats were euthanized with isoflurane, stomachs were dissected, and a gastric ulcer index was determined. RESULTS: The mean (+/- SD) ulcer index was 0.08 +/- 0.1 for group 1, 2.33 +/- 0.5 for group 2 (p = 0.01), 0.41 +/- 0.7 for group 3 (p = 0.037 compared with group 2), and 0.75 +/- 0.7 for group 4 (p = 0.0005 compared with group 2). Groups 3 and 4 were not significantly different from each other (p = 0.30). CONCLUSIONS: Gastric ulcerogenesis after CCT in the rat is decreased by anticholinergic and sympathomimetic drug pretreatment.

Analysis of Variance↗
PubMed1998

Air- and bone-conduction brainstem auditory evoked potentials and flash visual evoked potentials in cats.

OBJECTIVE: To document normal values for air- and bone-conducted brainstem auditory evoked potentials (BAEP) and for flash visual evoked potentials (VEP) in cats. ANIMALS: 10 mixed-breed cats (5 males) with normal physical, neurologic, otoscopic, and funduscopic examination results. PROCEDURE: BAEP in response to air- and bone-conducted click stimuli and VEP in response to flash stimuli were recorded to document species normative data. Mean and SD values were calculated for amplitudes and latencies of 4 peaks in the BAEP in response to air- and bone-conducted stimuli, and for latencies to 5 peaks and the 4 associated peak-to-peak amplitudes in the VEP. RESULTS: BAEP peak latencies increased and peak amplitudes decreased with decreasing stimulus intensity. Latencies were shorter for bone-conducted stimuli owing to the shorter transit time to the cochlea through bone, compared with air, but there were no differences for interpeak latencies. The BAEP and VEP recordings were similar to those reported for cats in other reports and were similar to those seen in other species. CLINICAL RELEVANCE: Normative data will permit performance of noninvasive electrodiagnostic evaluation of feline auditory and visual systems.

Acoustic Stimulation↗
PubMed1998

Effect of hyperbaric oxygen on lipid peroxidation in free skin grafts in rats.

OBJECTIVE: To document that free skin grafts treated with hyperbaric oxygen (HBO) are at greater risk for reperfusion injury, resulting in lipid peroxidation, than are free skin grafts without HBO treatment. ANIMALS: 40 Sprague-Dawley rats. PROCEDURE: Free skin grafting was performed bilaterally on each rat. The HBO-treated rats received HBO twice daily for 90 minutes at 2 ATA. Biopsy specimens were taken from each rat at the time of grafting and on days 2, 4, 7, 10, 14, 21, and 28, then were processed for tissue concentration of total glutathione (GSHt), glutathione peroxidase activity (GPx), and presence of thiobarbituric acid-reactive substances (TBARS). RESULTS: Both groups had a similar pattern of change in TBARS and GPx values--initial increase, returning to preoperative values at days 21 (control) and 28 (HBO). The GPx activity peaked later than did TBARS concentration (day 7 vs day 4). The pattern was significantly more pronounced in HBO-treated than in control rats. Both groups had a similar pattern of change in GSHt values-significant decrease from preoperative concentration at day 2, return to preoperative concentration by days 4 (HBO) and 7 (control), increase above preoperative concentration by day 21, and return to preoperative concentration by day 28. Obvious visual or histologic differences in the grafts were not detected between groups. CONCLUSIONS: Cellular effects of oxidative stress were apparent in both groups of rats; however, the degree of these effects was exacerbated by HBO. In the face of enhanced cellular lipid peroxidation, use of HBO for the treatment of free skin grafts must be questioned.

Animals↗
PubMed1996

Aetiology, prevalence and diagnosis of deafness in dogs and cats.

Peripheral deafness may be inherited or acquired, congenital or later-onset, and sensorineural or conductive. The most commonly observed forms are inherited congenital sensorineural, acquired later-onset sensorineural (ototoxicity, presbycusis) and acquired later-onset conductive (chronic otitis externa/media). In most dog and cat breeds inherited congenital sensorineural deafness results from perinatal degeneration of the stria vascularis, the vascular bed of the outer wall of the cochlear duct, which leads to hair cell degeneration. The strial degeneration appears to result from the absence of melanocytes, but their function in this structure is unknown. Ototoxicity may result from any of a large number of drugs and chemicals that directly or indirectly destroy cochlear hair cells. The effects are dose-dependent and in rare cases reversible. The most commonly recognized ototoxic drugs are the aminoglycoside antibiotics. Presbycusis, the ageing-related progressive hearing loss unattributable to other causes, is sensorineural but may also include mechanical changes in the tympanum and ossicles. Hearing aids may be accepted by some dogs as long as some residual function remains. Breeds reported to have been affected by congenital sensorineural deafness are listed and those with the highest prevalence are noted. Methods for diagnosis of deafness are described.

Animals↗
PubMed1995

Effect of deferoxamine and hyperbaric oxygen on free, autogenous, full-thickness skin grafts in dogs.

Free, autogenous, full-thickness skin grafts were applied to 10 dogs; 5 dogs were given an iron chelator, deferoxamine-10% hydroxyethyl pentafraction starch (DEF-HES; 50 mg/kg of body weight, IV), and 5 dogs were given an equal volume of 10% hydroxyethyl pentafraction starch (HES) in 0.9% saline solution (5 ml/kg, IV). All dogs (DEF-HES/HBO- and HES/HBO-treated) were exposed to 60 minutes of hyperbaric oxygen (HBO) at 2 atmospheres absolute pressure twice daily for 10 days, beginning the day of surgery. The percentage of viable graft on day 10 was lower in HES/HBO-treated dogs (mean +/- SD, 13.3 +/- 21.3%; median, 3.0%) than in DEF-HES/HBO-treated dogs (64.7 +/- 39.2%; 88.3%; P = 0.095, Mann-Whitney two-tailed test). There was a positive correlation between percentage of viable graft (on day 10) and percentage of haired skin on the graft site (on day 28) for all dogs (r = 0.91) and for HES/HBO-treated dogs (r = 0.97). The DEF-HES/HBO-treated dogs had less consistent correlation (r = 0.67). Perivascular aggregates of foamy cells were observed in the superficial and reticular portions of the dermis and in the subcutaneous tissue on both surfaces of the panniculus muscle in the graft sites of DEF-HES/HBO-treated dogs. These cells were also observed in the dermis, but not subcutaneous tissue of the control skin sections, and in some viscera of DEF-HES/HBO-treated dogs. Deferoxamine appears to attenuate the detrimental effect of HBO and HES on survival of free skin grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Ototoxicity assessment of a gentamicin sulfate otic preparation in dogs.

Vestibulotoxic and ototoxic effects often are seen after long-term, high-dose systemic treatment with gentamicin, but toxic effects after topical use have not been reported in animals, to the authors' knowledge. Vestibular and auditory effects of twice daily otic gentamicin treatment for 21 days were evaluated in 10 dogs with intact tympanic membranes and in the same 10 dogs after experimental bilateral myringotomy. Each dog served as its own control; 7 drops of gentamicin sulfate (3 mg/ml in a buffered aqueous vehicle) were placed in 1 ear, and 7 drops of vehicle were placed in the opposite ear. Treatment and control ears were reversed after myringotomy. Vestibular function was evaluated daily by neurologic examination and behavioral assessment. Auditory function was evaluated twice weekly by determination of brain stem auditory evoked potentials. Gentamicin sulfate placed in the ear of clinically normal dogs with intact or ruptured tympanic membranes, in the quantities used in this study, did not induce detectable alteration of cochlear or vestibular function. Serum gentamicin concentration after 21 days of treatment was detectable in only 2 dogs and was an order of magnitude below documented toxic concentrations.

Analysis of Variance↗
PubMed1993

Flash and pattern reversal visual evoked potentials in C57BL/6J and B6CBAF1/J mice.

Visual system responses (visual evoked potentials) to flash (FVEP) and pattern reversal (PRVEP) stimuli were recorded in mice. Two strains were used: black C57BL/6J mice and agouti B6CBAF1/J mice (first generation offspring of C57BL/6J females and CBA/J males.) Subjects were sedated with ketamine and xylazine. Flash rate (FVEP) and stimulus spatial frequency and pattern reversal rate (PRVEP) were varied to determine optimum stimulus parameters. Normative FVEP and PRVEP data were collected from mice of both strains after determination of optimum parameters. Five positive and four negative alternating peaks were routinely observed in the FVEP, while three positive and three negative alternating peaks were seen with the PRVEP. Varying the flash rate, the pattern reversal rate, and spatial frequency significantly affected nearly all amplitude and latency measures in the responses. Significant differences between strains were seen on some, but not all, latency and amplitude measures when the stimulus parameters were varied.

Animals↗
PubMed1993

Brain stem auditory evoked potentials from bone stimulation in dogs.

Brain stem auditory evoked potential (BAEP) testing with air-conducted click stimuli can be used to diagnose sensorineural deafness in dogs if conductive deafness can be ruled out. Detection of conductive deafness can be performed by recording BAEP elicited by a vibratory stimulus transducer placed against the skull. Air- and bone-conducted BAEP were compared in dogs, varying bone stimulator placement, click polarity, and stimulus intensity. Optimal bone stimulator placement was determined to be over the mastoid process, followed by the mandible and the zygomatic arch. Condensation polarity clicks gave responses preferable to those elicited by rarefaction or alternating polarity. Bone-conducted BAEP peak latencies were significantly longer than air-conducted latencies after correction of the latencies for the air conduction time accompanying air-conducted stimuli. Significant differences between stimulus modalities were not seen for BAEP peak amplitudes or interpeak latencies. Latency-intensity and amplitude-intensity regressions had similar effects for both modalities: latencies decreased and amplitudes increased as stimulus intensity increased.

Acoustic Stimulation↗
PubMed1992

Antagonism of kainic acid lesions in the mouse hippocampus by U-54494A and U-50488H.

A morphometric study of kainic acid- (KA) induced lesions was designed for the study of the interaction of the diamines U-5449A and U-50488H with excitatory amino acids, and the dose-response relationship thereof. IC50S determined for binding at the kappa receptor and other opioid receptors demonstrated the lack of kappa activity of U-54494A, a structurally related analog of U-50488H. Both opiate kappa receptor related anticonvulsant diamines were tested for their ability to protect the mouse hippocampus from the cytopathological changes induced by KA in neurons and glia. The damage observed with i.c.v. KA in mouse was restricted to neurons of the CA3 pyramidal region and glia of the hippocampus. It involved massive cell loss and shrunken neurons with dark cytoplasm and nuclei. Groups treated with combinations of KA and U-54494A or U-50488H showed scarce damage, but patches of necrotic changes were still observed. Control animals treated with saline (i.c.v.) and U-54494A (s.c.) or U-50488H (s.c.) did not suffer any noticeable alterations of the polymorphic layers of the hippocampal formation. Image analysis of the CA3 area of the hippocampus was used to quantitate the vacuolization induced by KA lesions in the control and treated groups. By this method, both U-54494A and U-50488H were shown to protect this area in a dose-related fashion as evidenced by reduced vacuolization. The anticonvulsant properties of these compounds may result in the antagonism of the excitotoxic lesions. More specifically, the ability of these diamines to block depolarization-induced influxes of Ca++ may protect the CA3 cells from the cytotoxic effects of persistent depolarization.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1992

Cortical somatosensory evoked potentials in cows.

A method was developed to record cortical somatosensory evoked potentials (SEP) from thoracic and pelvic limb stimulation in cows. Recordings were similar in latency and amplitude to those reported for horses. Correction for conduction pathway length did not alter the average latency values because the cows of the study were uniform in size; however, the data provided will enable use of this normative data with smaller or larger individual animals. Although latency variability for the SEP peaks was low, variability of the amplitude measurements was high. This observed variability was similar to that seen in other species. Validity of the recorded responses was indicated by lack of a tibial nerve SEP in 1 cow that had been given a tibial nerve conduction block, using lidocaine, and by repeatability of the response in 2 recordings taken 1 year apart in the same cow.

Animals↗
PubMed1991

Comparison of nerve regeneration through different types of neural prostheses.

Rat sciatic nerve regeneration through three synthetic neural prostheses was compared with regeneration through nerve allografts. The synthetic prostheses were either nonpermeable nonabsorbable (Silastic), permeable absorbable (polyglactin mesh), or permeable nonabsorbable (polypropylene mesh). Animals were evaluated at 10, 24, and 90 days. Functional analysis of nerve regeneration was performed by noninvasive methods: electromyography and walking tracks. Nerve tissue was examined with routine histologic and immunofluorescent techniques. A compressive neuropathy developed with the use of the Silastic implant. A neutrophilic inflammatory infiltrate was consistently associated with implantation of the polyglactin mesh. A strong connective tissue response was noted around the polypropylene mesh. Early recovery of nerve function was seen with the Silastic implants, however, overall nerve function was best in the nerve allograft and polypropylene mesh groups. Polyglactin implantation increases the local inflammatory response and should not be used for nerve anastomoses. If Silastic entubulation is used, it should be removed between 24 and 90 days.

Animals↗
PubMed1991

Hyperbaric oxygen effects on brown recluse spider (Loxosceles reclusa) envenomation in rabbits.

Human loxoscelism was modeled in albino rabbits by injection of brown recluse spider (Loxosceles reclusa) venom, and the effects of daily or twice-daily hyperbaric oxygen treatment on wound healing were investigated. Lesions similar to those seen in humans were produced in rabbits by intradermal injection of 200 microliters of a venom extract (0.21 microgram protein per microliter), including edema and erythema, ischemia and cyanosis in the first 12 hr, extensive purpura by 24 hr, and crateriform ulcer formation by day four, with induration and eschar formation. Hyperbaric oxygen treatments, consisting of two atmospheres absolute (2 ATA) for 60 min, were applied daily (n = 8) or twice daily (n = 8), while control animals (n = 8) received no treatment. Treatments were initiated 72 hr after venom injection (day 3) to duplicate typical clinical treatment delays, and were administered for seven consecutive days. No significant effects of hyperbaric oxygen treatment on lesion healing were seen as measured by lesion area. However, histologic evaluation of wound tissue collected at euthanasia on day 24 showed clear differences between rabbits receiving twice-daily treatments and those receiving daily or no treatment. The former showed complete re-epithelization or slight ulceration, while the latter usually had necrotic cavities extending into the dermis, with myonecrosis and inflammatory cell accumulation. Thus, no superficial differences were seen between groups, but twice-daily treatments resulted in enhanced recovery at the histologic level.

Animals↗
PubMed1991

Electroretinogram and visual-evoked potential measurements in sheep.

Electroretinogram (ERG) and visual-evoked potential (VEP) recordings were taken from ten Suffolk-cross sheep. Stimuli for VEP were 1.5 flashes of white light/s; ERG stimuli were single flashes. The ERG measurements of the a and b wave latencies and a-to-b amplitude were measured between the lower eyelid and the vertex, with ground on the nuchal crest. The VEP after monocular stimulation were measured between the nuchal crest and the interorbital line, with ground on the vertex. Measurements consisted of the latencies to seven alternating positive and negative peaks P1, N1, P2, N2, P3, N3 and P4, and six amplitudes, P1-N1, N1-P2, P2-N2, N2-P3, P3-N3 and N3-P4. Average latencies for the a and b waves were 13.6 and 28.2 ms; the mean ab amplitude was 131.68 microV. Average latencies for the seven VEP peaks were 35.0, 43.1, 52.8, 64.1, 74.5, 90.4 and 112.2 ms. Mean amplitudes ranged from 3.90 to 8.29 microV.

Animals↗