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Biomedical subjects

D W Shucard

Publications and source records attributed to D W Shucard.

At least 55 records · Page 3Linked to original sources
PubMed1978

A naturally occurring antibody in New Zealand mice cytotoxic to dissociated cerebellar cells.

A spontaneously occurring antibody cytotoxic to dissociated cells of the neonate mouse cerebellum was found in the sera of some New Zealand (NZ) mice. No significant activity was found in the sera of six non-autoimmune mouse strains. The degree of cytotoxicity was similar towards both allogeneic and syngeneic cells. Absorption of the cytotoxic sera with brain and kidney homogenates removed the reactivity, while liver removed less reactivity. Absorptions with thymocytes and several other tissue homogenates and cells had no effect on the cytotoxicity levels, nor was there a correlation between the levels of thymocytotoxicity and cerebellar cell cytotoxicity. The antibody cytotoxic for cerebellar cells could not be demonstrated in the cerebrospinal fluid (CSF) of any mice examined, including a mouse with high serum cytotoxic levels. Gel filtration of reactive sera indicated that the antibody is of the IgM class.

Animals↗
PubMed1977

Auditory evoked potentials as probes of hemispheric differences in cognitive processing.

The amplitude of auditory evoked potentials recorded from the cerebral hemispheres to pairs of task-irrelevant tones was related to differential hemispheric engagement in ongoing cognitive activity (for example, verbal versus musical). The hemisphere hypothesized to be most engaged in the ongoing cognitive task, as compared to the unengaged hemisphere, produced a greater potential difference between the temporal and reference electrode to the second of the tone pairs. These findings are related to "fast habituation" and "recovery cycle.".

Adult↗
PubMed1977

Atropine-induced bradycardia in the guinea pig: dose-response.

The effect of atropine sulfate on the heart rate of the unanesthetized guinea pig was studied using a wide range of doses injected via a chronic jugular cannula; dose-response data are presented for the range of 5 mg/kg to 50 mg/kg. A long-lasting dose-dependent bradycardia was produced. This finding is in contrast to the clasically reported effect of atropine in man and dog: tachycardia sometimes preceded by a transient bradycardia. Thus, the guinea pig may be an excellent model for the study of parasympathomimetic, bradycardia-producing effects of atropine.

Animals↗
PubMed1975

A safe and fast-acting surgical anesthetic for use in the guinea pig.

Ketamine [dl-2-(o-chlorophenyl)-2-(methylamino)cyclohexanone] hydrochloride was used in conjunction with Acepromazine [10-3-(dimethylamino)-propyl]phenothiazin-2-yl-methyl ketone] Maleate to produce surgical depth anesthesia in guinea pigs. In tests with 97 animals, an intramuscular injection of 44 mg/kg ketamine hydrochloride plus 2 mg Acepromazine Maleate was found to be effective in producing a surgical level of anesthesia within 2 min after administration. The anesthetic state lasted for an average of 1.5 h and could be safely extended by supplemental administrations of the drugs. This anesthetic combination was found to be fast acting, safe, and easily controlled.

Acepromazine↗
PubMedDate not supplied

Sequential use of standard and ambulatory EEG in neonatal seizures.

Adequate predictors do not exist to indicate whether seizures are likely to continue beyond the neonatal period. Thirteen neonates with seizures occurring after 7 days of age were evaluated with standard short-term electroencephalography (SEEG) during the initial seizures and with ambulatory EEG (AEEG) when each infant was within 37-44 weeks corrected age (i.e., gestational age plus chronologic age). Eight of 13 SEEGs, 10 of 13 AEEGs, and 12 of 13 with the combined use of both SEEGs and AEEGs accurately predicted the occurrence of seizures at 3-4 months corrected age. Results with SEEG and AEEG did not produce significantly different outcomes. Combined analysis of SEEG and AEEG produced significantly different results from those calculated when the two EEG types were analyzed independently (Z = 3.98, p less than 0.001). The findings indicate that the use of both of these tests may improve the ability to predict continued seizure activity in infants with neonatal seizures when compared to the use of each measure separately.

Behavior↗
PubMedDate not supplied

Theophylline-induced changes in the mouse brainstem auditory evoked potential.

Because theophylline is a widely used analeptic, there is interest in its possible ototoxic and neurotoxic effects. The present study used the brainstem auditory evoked potential (BAEP) to evaluate the acute effects of theophylline on auditory electrophysiology in mice. Adult female C57BL/6 mice were injected intraperitoneally with 150 mg/kg theophylline or saline. The BAEP thresholds and latency-intensity profiles suggested that theophylline induced a rather slight but statistically significant change in auditory function that was suggestive of a temporary recruitment-type sensorineural deficit. This observation raises concerns about the possible ototoxic effects of theophylline, particularly in asthmatic patients and apneic preterm neonates who receive this drug chronically. While there was BAEP evidence of ototoxic effects for theophylline, there was no evidence of neurotoxic effects.

Animals↗
PubMedDate not supplied

Simple apparatus for blocking small animal brains.

A modification of previously described devices for blocking small animal brains is presented. The apparatus is easily constructed and allows for blocking at varous angles of both fixed and unfixed tissue of most small laboratory animals.

Animals↗
PubMedDate not supplied

Chronic immune complex disease: behavioral and immunological correlates.

Using a fear avoidance paradigm, behavioral effects were seen in Sprague-Dawley rats in which chronic immune complex disease was induced. These effects were related to changes in urine protein that developed during the course of the experiment. Experimental animals also had glomerular deposits of rat gamma globulin and BSA as determined by immunofluorescence; C3 deposits were observed in half of these animals. BSA and/or rat gamma-globulin, but not C3, was seen in the choroid plexus of half of the experimental animals. This is the first study to report behavioral changes associated with the induction of chronic immune complex disease in experimental animals.

Animals↗