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Biomedical subjects

R L Perry

Publications and source records attributed to R L Perry.

27 records · Page 2Linked to original sources
PubMed1975

Effects of neophobia and habituation on the poison-induced avoidance of exteroceptive stimuli in the rat.

Two experiments on the role of neophobia in poison-induced aversions to exteroceptive stimuli are reported. In Experiment 1, rats were given either 10 or 25 days of habituation to the test situation prior to conditioning. Those animals with the longer habituation period avoided a complex of novel exteroceptive stimuli while those with the shorter habituation period did not. In Experiment 2 rats initially avoided the more novel of two containers, but gradually came to eat equal amounts from both. A single pairing of toxicosis with consumption from either the novel or the familiar container reinstated the avoidance of the novel container in both cases. The results were discussed in terms of an interaction between habituation and conditioning procedures. It was suggested that previously reported differences between interoceptive and exteroceptive conditioning effects may have been influenced by the differential novelty of the two classes of stimuli in the test situation. It was further suggested that non-contingently poisoned control groups should routinely be included in poison avoidance conditioning studies.

Animals↗
PubMedDate not supplied

Pregnancy in early adolescence: are there obstetric risks?

The purpose of this study was to determine if early adolescence imparts a significant obstetric risk in young primiparas relative to adult primiparas. The records of 239 young primiparas (< 16 years) and 148 older primiparas (18-29 years) were reviewed for demographic information, antepartum complications, mode of delivery, length of labor, episiotomy, lacerations, birthweight, and length of gestation. The young adolescents were shorter, had an earlier age at menarche, a lower pregravid body mass index, and a higher gestational weight gain. The young teens were less likely to smoke cigarettes but were more likely to be Medicaid recipients. The incidence of most antenatal complications (chronic hypertension, pregnancy-induced hypertension, placental abruption, placenta previa, premature rupture of the membranes, urinary tract infections, and anemia) were similar between the two groups. Preterm labor and contracted pelvis were more common among the young adolescent, while gestational diabetes was less common. The young primiparas were significantly (P < .05) less likely to have a Cesarean delivery and to lacerate with vaginal delivery. The length of labor and its stages were similar, as were overall birthweight and length of gestation. Thus, obstetric concerns regarding pregnancy in early adolescence may be unfounded. With the exception of an increased risk for preterm labor, it appears that pregnancy, labor, and delivery do not pose inordinate obstetric and medical risk to the very young adolescent primipara.

Adolescent↗
PubMedDate not supplied

Effect of tibial plateau leveling on cranial and caudal tibial thrusts in canine cranial cruciate-deficient stifles: an in vitro experimental study.

OBJECTIVES: To investigate the effect of tibial plateau leveling (TPL) on tibial subluxation and tibial axial rotation; to determine the minimal tibial plateau rotation (MinTPR) angle that provides stifle stability; and to evaluate caudal cruciate ligament (CaCL) strain following tibial plateau rotation in cranial cruciate ligament (CrCL)-deficient stifles. ANIMALS: Fifteen canine cadaver hind limbs. METHODS: Tibial subluxation was measured from lateral radiographs in intact, loaded stifles and after sequential CrCL transection, MinTPR, TPL, and CaCL transection. The MinTPR angle was determined using a custom-made hinge plate and compared with the TPL angle. Tibial axial rotation was evaluated in CrCL-deficient stifles before and after TPL. Finally, CaCL strain was recorded in intact, loaded stifles, and following MinTPR, TPL, and tibial plateau over-rotation (MaxTPR) using a force probe. RESULTS: Cranial tibial subluxation in CrCL-deficient stifles was eliminated with TPL. Tibial plateau rotation, however, induced caudal tibial subluxation, which significantly increased from MinTPR to TPL before and after CaCL transection. The MinTPR angle was 6.5 degrees +/- 0.9 degrees less than the TPL angle (P <.05). Tibial internal rotation decreased significantly after TPL in CrCL-deficient stifles. Finally, CaCL strain increased with increasing tibial plateau rotation. CONCLUSIONS: This study suggests that, during stance phase, TPL transforms cranial tibial thrust into caudal tibial thrust, thereby stabilizing the stifle in the cranio-caudal plane via the constraint of the CaCL. The increase in CaCL stress, which results from tibial plateau rotation, could predispose the CaCL to fatigue failure and therefore would caution against tibial plateau over-rotation.

Animals↗
PubMedDate not supplied

The effect of triple pelvic osteotomy on hip force in dysplastic dogs: a theoretical analysis.

The effect of a triple pelvic osteotomy (TPO) procedure on the forces acting about the hip joint was examined in five dysplastic canine hips using a previously described theoretical analysis. Hip reaction force (Fh) and its angle of application (theta h) were calculated from radiographic measurements made before and after TPO procedures which sequentially increased acetabular ventroversion from 0 degree to 20 degrees, 30 degrees, and 40 degrees. The results of the in vitro study showed that Fh decreased with increasing acetabular ventroversion reaching an asymptotic value between 30 degrees and 40 degrees. The decrease in Fh corresponded to an increase in theta h toward the vertical, with statistical significance found in both Fh and theta h between 0 degree and 20 degrees. The changes observed in Fh and theta h after TPO were attributed to the medialization of the femoral head resulting from the reduction of the subluxated head. The results of this study suggest that the noted reduction in the magnitude of the forces acting on the hip joint may act in concert with increased coverage of the femoral head to effect the beneficial clinical results observed with the TPO procedure.

Animals↗
PubMedDate not supplied

The effect of triple pelvic osteotomy on the articular contact area of the hip joint in dysplastic dogs: an in vitro experimental study.

OBJECTIVE: To investigate the effect of triple pelvic osteotomy (TPO) on articular contact area and acetabular coverage of dysplastic hip joints in dogs. STUDY DESIGN: Articular contact area and femoral head coverage by the acetabulum were computed in vitro in normal and dysplastic canine hips. The effect of TPO on articular contact and coverage was then analyzed in the dysplastic hips. Sample Population-Five normal and six dysplastic canine cadaver specimens. METHODS: Contact area and coverage of loaded hips were computed using serial computed tomography scan images before and after TPO. Three angles of acetabular ventroversion (AVV) were studied (20 degrees, 30 degrees, and 40 degrees). Using a custom-designed hinge plate, angles of spontaneous hip reduction in dysplastic hips were compared with previously recorded angles of reduction determined by the Ortolani test. RESULTS: Contact area significantly increased from 0 degrees to 30 degrees of AVV, then remained virtually unchanged. Coverage significantly increased from 0 degrees to 20 degrees of AVV. Both contact and coverage of normal hips were similar, yet significantly smaller than those of dysplastic hips once reduction had occurred. The experimental angles of reduction were significantly smaller and poorly correlated with the angles of reduction determined by the Ortolani test. Although coverage continued to increase with AVV, the actual joint contact area did not significantly vary after relocation of the femoral head. CONCLUSIONS: This study suggests that increasing AVV beyond 20 degrees does not significantly improve the beneficial effects of TPO and therefore should be carefully weighed against increased risks of postoperative complications associated with large angles of AVV.

Analysis of Variance↗
PubMedDate not supplied

Regression of hypertrophic osteopathy in a cat after surgical excision of an adrenocortical carcinoma.

A 12-year-old, spayed, female domestic shorthair cat was diagnosed with severe and extensive hypertrophic osteopathy of the appendicular skeleton. Diagnostic ultrasound detected a mass lesion in the right adrenal gland. A right adrenalectomy was performed, and histopathological examination confirmed an adrenocortical carcinoma. No radiographic evidence of pulmonary metastasis was found on initial presentation or recheck thoracic radiographs taken 15 weeks later. Almost complete regression of periosteal new bone formation occurred 15 weeks following the successful surgical removal of the adrenal tumor.

Adrenal Cortex Neoplasms↗
PubMedDate not supplied

Medical computing: present & future.

By the end of 1984, as many as one third of all solo practices and two thirds of group practices will have purchased a computer. As many as 25% of these practices, however, will derive only limited benefit from their investment.

Computers↗