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Biomedical subjects

E Shepherd

Publications and source records attributed to E Shepherd.

At least 19 recordsLinked to original sources
PubMed2001

A placebo-controlled study of guanfacine in the treatment of children with tic disorders and attention deficit hyperactivity disorder.

OBJECTIVE: This study evaluated the efficacy and safety of guanfacine in treating children with tic disorders and attention deficit hyperactivity disorder (ADHD). METHOD: Subjects from a specialty tic disorders clinic were randomly assigned to receive 8 weeks of treatment with guanfacine or placebo under double-blind conditions. Follow-up visits occurred every 2 weeks for safety monitoring and dose adjustment. RESULTS: Thirty-four medication-free subjects (31 boys and three girls with a mean age of 10.4 years) with ADHD, combined type, and a tic disorder participated. After 8 weeks of treatment, guanfacine was associated with a mean improvement of 37% in the total score on the teacher-rated ADHD Rating Scale, compared to 8% improvement for placebo. Nine of 17 subjects who received guanfacine were blindly rated on the Clinical Global Improvement scale as either much improved or very much improved, compared with none of 17 subjects who received placebo. The mean score on the parent-rated hyperactivity index improved by 27% in the guanfacine group and 21% in the placebo group, not a significant difference. On the Continuous Performance Test, commission errors decreased by 22% and omission errors by 17% in the guanfacine group, compared with increases of 29% in commission errors and of 31% in omission errors in the placebo group. Tic severity decreased by 31% in the guanfacine group, compared to 0% in the placebo group. One guanfacine subject with sedation withdrew at week 4. Guanfacine was associated with insignificant decreases in blood pressure and pulse. CONCLUSIONS: Guanfacine appears to be a safe and effective treatment for children with tic disorders and ADHD.

Adolescent↗
PubMed2000

Big endothelin-3 constricts forearm resistance vessels but not hand veins in humans.

BACKGROUND: Endothelin-3 (ET-3) and its inactive precursor, big endothelin-3 (big ET-3), are both found in human plasma. We investigated whether big ET-3 is converted to ET-3 in the human forearm resistance vessels and dorsal hand veins in vivo. METHODS: In a 4-phase study, 6 subjects received 90 minute intrabrachial artery infusions of big ET-3 (50 and 100 pmol x min(-1)) and ET-3 (5 and 10 pmol x min(-1)) in random order. Forearm blood flow was measured by venous occlusion plethysmography. In a second 3-phase study, 6 subjects received 90-minute dorsal hand vein infusions of saline solution, big ET-3 (50 pmol x min(-1)) and ET-3 (5 pmol x min(-1)) in random order. In a third 2-phase study, 6 subjects received 90-minute dorsal hand vein infusions of big ET-3 (100 pmol x min(-1)) and ET-3 (10 pmol x min(-1)). In the dorsal hand vein studies, vessel diameter was measured by the Aellig technique. RESULTS: Intra-arterial ET-3 caused local forearm vasoconstriction of 20%+/-9% (P = .009) at 5 pmol x min(-1) and 20%+/-10% (P = .001) at 10 pmol x min(-1) after 90 minutes, with no difference between doses (P = .69). Intra-arterial big ET-3 also caused local forearm vasoconstriction of 22%+/-6% at 50 pmol x min(-1) (P = .004) and 18%+/-3% at 100 pmol x min(-1) (P<.0001) after 90 minutes, with no difference between doses (P = .44). There were no significant differences between the responses to intra-arterial big ET-3 and ET-3 at these doses. Local intravenous ET-3 caused a constriction of 9%+/-2% at 5 pmol x min(-1) (P = .04) and 22%+/-8% at 10 pmol x min(-1) (P = .002) after 90 minutes. Big ET-3 at 50 pmol x min(-1) and 100 pmol x min(-1) did not affect hand vein tone. All responses were slowly progressive. CONCLUSIONS: Based on vasoconstriction, measurable conversion of big ET-3 to ET-3 occurs in forearm resistance vessels but not in dorsal hand veins in vivo. An endothelin-converting enzyme, capable of converting exogenously administered big ET-3 to ET-3, appears to be present in upper limb resistance arteries but not in capacitance vessels in humans.

Adult↗
PubMed1997

Morphology and matrix composition during early tendon to bone healing.

This study outlines the early morphologic phenomenon of tendon to bone healing in the rabbit model. Twelve skeletally mature, male New Zealand White rabbits received transplantation of the hallucis longus tendon into a 2-mm calcaneal bone tunnel. The morphologic characteristics of the healing tendon to bone interface were evaluated at 1, 2, 4, and 6 weeks after surgery by the use of conventional histology and immunohistochemical localization of collagen Types I, II, and III. Histologic analysis illustrated progressive maturation and reorganization of the tendon to bone interface with subsequent development of tissue collagen fiber continuity between the tendon and bone. Initially, diffuse immunolocalization of all three collagen types was observed within the scar tissue filling the space between the tendon and bone. During a 6-week period, reorganization of the scar tissue into an interface occurred, similar to an indirect insertion. Although a definitive fibrocartilage region did not form, Type II collagen was localized at the remodeling insertion site throughout the first 6 weeks of repair. In addition, Type III collagen fibers, resembling Sharpey's fibers, were noted to span this interface. The characterization of the insertion between tendon and bone is important to the understanding of healing in commonly used orthopaedic grafting procedures, such as anterior cruciate ligament reconstructions.

Animals↗
PubMed1996

Semirigid instrumentation in the management of lumbar spinal conditions combined with circumferential fusion. A multicenter study.

STUDY DESIGN: Patients with the diagnosis of degenerative disc conditions or spondylolisthesis undergoing circumferential fusion with posterior pedicle screw fixation using a semirigid rod were reviewed. OBJECTIVES: To determine the effectiveness of this approach in achieving a spinal fusion and satisfactory clinical outcome, and to determine the complications associated with the procedure. SUMMARY OF BACKGROUND DATA: The use of instrumentation to stabilize the lumbar motion segments and thereby enhance the fusion rate has been proposed in a number of studies. Semirigid fixation was believed to be effective in achieving these objectives without concern for stress-shielding, which was suggested by some authors using rigid fixation systems. METHODS: Patients who required spinal fusion with anterior and posterior approaches because of specific lumbar pathology or previous surgeries were selected. The surgery consisted of an anterior interbody fusion using allograft, followed by a posterolateral fusion and pedicle screw fixation. Fusion was determined by continuity of trabecular bridging, and outcomes were determined by pain reduction and return to previous levels of activity. Fusion was considered solid if the two posterolateral areas were fused (Zones one and two), if the anterior interbody area was fused (Zone three), or if all three zones were fused. Complications were documented during and after surgery. RESULTS: Sixty-two percent of patients had previous surgery with 25% of these patients having a diagnosis of pseudarthrosis. Fifty-five percent of patients had two or more levels fused, and 43% were heavy smokers. Ninety-seven percent of patients had successful fusions. Pain was significantly reduced on a pain analogue scale from 7.1 to 2.1 in the back and from 5.8 to 1.5 in the leg (p < 0.006 and 0.0001, respectively). Fifty-nine percent of patients returned to their previous level of activity, and 18% returned to lighter work or job retraining, for a total of 77% returning to the same or lighter levels of activity. Complications included metal failure, 4.9%; neurologic deficit, 1.2%; deep infection, 1.2%; deep venous thrombosis, 4.9%; and vascular injury, 2.4%. Fatal pulmonary embolus occurred in one patient. CONCLUSION: This technique produces a satisfactory fusion rate (97%) and a good clinical outcome based on pain reduction and return to a satisfactory level of activity (77%). It is associated with few, but significant, complications that compare well with other reported series in a difficult group of patients. This procedure should be reserved for patients who are considered to be at high risk for not achieving spinal fusion.

Adolescent↗
PubMed1980

Efficacy of albendazole and levamisole in sheep against Thysanosoma actinioides and Haemonchus contortus from the Edwards Plateau, Texas.

Lambs naturally infected with Thysanosoma actinioides and naturally and experimentally infected with Haemonchus contortus were used in a controlled experiment to determine the anthelmintic activity of albendazole as compared with levamisole. The lambs were given 10,000 H contortus larvae 25 to 35 days before treatment, were slaughtered 7 to 9 days after treatment, and were housed on concrete from the time of treatment until slaughter. In lambs given doses of 7.5 mg or 3.8 mg of albendazole/kg or 7.5 mg of levamisole/kg, reductions in numbers of H contortus were 99%, 85%, and 98%, respectively. Reductions in numbers of T actinioides were 98%, 45%, and 0% respectively, as compared with untreated controls.

Albendazole↗