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Biomedical subjects

D L Greene

Publications and source records attributed to D L Greene.

17 recordsLinked to original sources
PubMed2001

Anatomic study of the medial neurovascular structures in relation to calcaneal osteotomy.

Medial displacement osteotomy of the calcaneous is commonly performed for stage II posterior tibial tendon insufficiency in an effort to improve the valgus deformity of the hindfoot. We performed an anatomic study examining the medial neurovascular anatomy and its relation to the osteotomy in an attempt to determine which structures may be at risk during the procedure. Calcaneal osteotomies were performed through a lateral approach on 22 fresh-frozen cadaver below-knee specimens. Dissection was then performed medially to identify the Medial Plantar Nerve (MPN), the Lateral Plantar Nerve (LPN), the Posterior Tibial Artery (PTA), and their respective branches. Measurements determined either 1) where the structure crossed the osteotomy or 2) if the structure did not cross, the closest perpendicular distance from the osteotomy and at which point along its length this occurred. Perpendicular distances were recorded in millimeters and position along the osteotomy as a percentage of the total length from the posterosuperior aspect. An average of four neurovascular structures crossed each osteotomy site (range 2 to 6), most of which were branches of the LPN or the PTA. The MPN did not cross in any of the specimens studied, the LPN crossed in one specimen, and the PTA crossed in two specimens. The MPN distributed no crossing branches. The calcaneal sensory branch of the LPN was identified and crossed in 86% of the cadavers at 19% (+/- 15%) along the osteotomy length. A more distal second branch of the LPN (Baxter's nerve) was identified and crossed in 95% of the specimens at 61% (+/ 20%) along the osteotomy length. A third crossing branch existed in one specimen. Each PTA distributed from zero to three branches which variably crossed the osteotomy at a point from 2% to 100% along its length. The PTA bifurcated in 77% of the specimens at 49% (+/- 9%) along the osteotomy length. A consistent finding in every specimen was the presence of two veins accompanying the PTA with one on either side. A number of medial neurovascular structures may be at risk when perfoming a calcaneal osteotomy through a lateral approach. A minimum of two structures crossed the osteotomy site at variable positions in this study, although most of these structures represented branches off of the LPN or the PTA, with the LPN and the PTA themselves crossing only infrequently. The authors recommend that the completion of the osteotomy through the medial calcaneal cortex be performed in a carefully controlled manner to reduce the risk of post-operative complications including pain, numbness, and hematoma formation.

Calcaneus↗
PubMed1999

Bilateral asymmetry in skeletal growth and maturation as an indicator of environmental stress.

This study examined the efficacy of bilateral asymmetry in epiphyseal union as an indicator of environmental stress affecting the skeleton. We compared the extent of asymmetry in the postcranial skeleton between two cemetery samples excavated from Medieval Kulubnarti, Sudanese Nubia. Past studies have strongly suggested that these ancient Nubians experienced environmental stress-the early Christian period (550-750 AD) population to a greater extent than the late Christian period (750-1450 AD) population. We hypothesized that if bilateral asymmetry is a reflection of stress, then it should be present or greater in the more stressed population, the early Christian period population, while absent or found to a lesser extent in the less stressed population, the late Christian period population. We computed two mean values, representative of right-side and left-side epiphyseal union, for each individual in both cemetery samples, and tested for significant differences. Bilateral asymmetry was significant in the combined cemetery sample of 90 individuals (P < 0.019). When cemetery samples were tested separately, bilateral asymmetry was significant for the early Christian period sample (P < 0.001), but not for the late Christian period sample. There were no differences attributable to sex. Finally, we discuss why we conclude that environmental stress was favored over a biomechanic explanation as the cause for asymmetry. To the extent that our results support previous findings that early Christian period individuals were more affected by environmental stress than late Christian period individuals, it is reasonable to consider bilateral asymmetry in skeletal growth and maturation a good indicator of environmental stress.

Adolescent↗
PubMed1996

Enkephalin analog prodrugs: assessment of in vitro conversion, enzyme cleavage characterization and blood-brain barrier permeability.

To improve the blood-brain barrier penetration of the delta-opioid receptor peptides [D-Pen2, D-Pen5]enkephalin (DPDPE) and [D-Pen2, L-Cys5]enkephalin (DPLCE), various prodrug forms were synthesized to increase lipophilicity and drug delivery to the brain. The aims of this study were 3-fold, 1) to assess the metabolic conversion of various DPDPE and DPLCE prodrugs in vitro using mouse brain homogenate and mouse serum, 2)to characterize the proteolytic enzymes responsible for cleaving prodrugs to the parent compounds using select peptidase inhibitors and 3)to assess the blood-brain barrier permeability of prodrugs, compared with their parent compounds, using the in vitro bovine brain microvessel endothelial cell culture model. The prodrugs with carboxyl-terminal phenylalanine residues (DPDPE-Phe and DPLCE-Phe) had significantly longer metabolic conversion times in both mouse serum and brain homogenates than did the prodrugs with amino-terminal phenylalanine residues. Inhibition of leucine aminopeptidase with bestatin in the serum increased the conversion time of Phe0-DPDPE from 6.8 min to 92.2 min. Inhibition of aminopeptidase M with amastatin in the brain homogenate increased the conversion time of Phe0-DPDPE from 3.9 min to > 450 min. The long half-life of DPLCE-Arg-Pro-Ala in serum (317 min) vs. brain (9.2 min) can be explained by the high levels of the degradative endopeptidase 24.15 (EC 3.4.24.15) in the central nervous system but not in plasma. The data also showed that, for specific prodrugs of DPDPE such as Phe0-DPDPE and DPDPE-Arg-Gly, the prodrug shows a significant improvement in permeability, compared with the parent compound. Therefore, these data provide evidence that prodrugs or prodrug-enzyme inhibitor combinations may optimize the delivery of peptide and/or protein drugs to the central nervous system.

Analgesics↗
PubMed1993

Reactive lysis--a phenomenon of delayed hemolytic transfusion reactions.

A 62-year-old female with Gaucher's disease demonstrated alloanti-c on pretransfusion testing. She was transfused with five units of c-negative red blood cells (RBCs) preoperatively and intraoperatively. The hemoglobin (Hb) level was slightly lower initially, hut was markedly lower on day 10 posttransfusion. Serologic results indicated a delayed hemolytic transfusion reaction (DHTR) due to alloanti-s, -Fya, and -Jkb, present both on the RBCs and in the serum. As late as day 35 posttransfusion, a mixed-field anti-IgG direct antiglobulin test (DAT) indicated that there were two cell populations present. The DAT remained positive with anti-C3b, -C3d throughout the course of the reaction. Because of the substantially lower Hb and the severity of symptoms, immunologic clearance of the antigen-positive donor RBCs was expected. However, we demonstrated their persistence. Our data corroborates the observation that complement activation occurring during DHTRs can result in the hemolysis of innocent bystander (autologous) cells.

Journal Article↗
PubMed1992

Whole body and brain distribution of [3H]cyclic [D-Pen2,D-Pen5] enkephalin after intraperitoneal, intravenous, oral and subcutaneous administration.

The route of administration of a given drug can have a significant influence upon whole body distribution. The present study examined whole body distribution of the delta opioid receptor-selective peptide [3H]DPDPE in male CD1 mice after administration by several routes. Additionally, we describe regional brain distribution of [3H]DPDPE after i.v. administration with and without pretreatment with naloxone or the selective delta receptor antagonist naltrindole. Finally, characterization of the inherent enzymatic stability of DPDPE was also examined. Intravenous administration results in a significantly large amount of [3H]DPDPE in the small intestine and flush at 15 and 30 min postadministration, suggesting rapid biliary excretion. The highest level in the brain after i.v. administration occurred at 60 min (0.08%). After i.p. and s.c. administration, large amounts of [3H]DPDPE were found in the small intestine and flush, but not until 60 min postadministration, suggesting a slower rate of absorption from the site of administration. The i.p. and s.c. groups' brain levels peaked at 120 min (0.07 and 0.09%, respectively). The highest levels in the brain after p.o. administration were seen at 240 min (0.03%). Examination of regional brain distribution data showed no significant difference in the levels of [3H]DPDPE between brain regions at any time point studied. However, naloxone pretreatment resulted in significant reductions of [3H]DPDPE in all brain regions at 5 and 10 min. Naltrindole pretreatment resulted in significant reductions in the frontal cortex and striatum at 5 and/or 10 min postadministration, but had no effect on [3H]DPDPE levels in cerebellum, hippocampus or brain stem.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Distribution and analgesia of [3H][D-Pen2, D-Pen5]enkephalin and two halogenated analogs after intravenous administration.

To improve pharmacological characteristics of the delta-selective, cyclic peptide [D-Pen2, D-Pen5]enkephalin (DPDPE), modification by halogenation at the Phe4 residue was undertaken. The present study was to determine the extent [3H]DPDPE, [3H][p-Cl-Phe4]DPDPE and [p-125IPhe4]DPDPE crosses the blood-brain barrier, elicits analgesia and to characterize selective organ distribution and stability after i.v. administration. A significantly greater percentage of total [3H][p-Cl-Phe4]DPDPE reached the brain after 10, 20 and 40 min as compared to [3H]DPDPE and both peptides were significantly displaced by pretreatment with naloxone or naltrindole. The amount of [3H]DPDPE detected in the brain was greater than that of [p-125IPhe4]DPDPE. Distribution results revealed large amounts of the administered peptides were sequestered rapidly in the gall bladder and secreted into the small intestine. Hot-plate antinociception tests 5 min after i.v. administration (30 and 60 mg/kg) revealed [p-Cl-Phe4]DPDPE to elicit a much greater analgesic effect as compared to DPDPE or [p-125IPhe4]DPDPE. These results provide evidence that [p-Cl-Phe4]DPDPE has a greater apparent distribution to the brain and has a greater effect on the antinociception threshold as tested on the hot-plate than DPDPE or [p-125IPhe4]DPDPE. Stability of unlabeled and tritiated DPDPE and [p-Cl-Phe4]DPDPE was determined both in vitro and in vivo; both unlabeled and tritiated DPDPE and [p-Cl-Phe4]DPDPE remain intact.

Analgesics↗
PubMed1984

Fluctuating dental asymmetry and measurement error.

Differences between the dimensions of left and right molar teeth are analyzed in the context of measurement error while considering the power of the F-Ratio. Molar teeth from two Nubian cemeteries, 24-S-46 and 21-R-2, excavated at Kulubnarti, Sudan, were initially measured, and then remeasured to obtain data for assessing fluctuating dental asymmetry and measurement error. As has been demonstrated by other investigators, the power of the F-Ratio for detecting small, but real differences, that might exist between antimeric dimensions when sample sizes are small, as they usually are with archeological materials, limits interpretation. In addition, an analysis of measurement error indicates that such error can have a confounding effect upon interpretations of the degree of fluctuating dental asymmetry that exists even in very large samples that exceed the size of typical archeological samples.

Humans↗
PubMed1982

Discrete dental variations and biological distances of Nubian populations.

During the 1963-1964 field season, the University of Colorado's Nubian Expedition excavated a series of Meroitic, X-Group, and Christian cemeteries from Wadi Halfa Sudan. Recently a joint expedition sponsored by the Universities of Colorado and Kentucky excavated two additional Christian cemeteries from Kulubnarti, some 80 miles south of Wadi Halfa. Earlier analysis of discrete dental variations demonstrated that the Wadi Halfa populations did not differ significantly from one another. Application of the Smith-Grewal multivariate measure of biological divergence, as modified by Sjøvold,, and Green and Suchey, corroborates the original conclusion of biological stability and continuity for the Wadi Halfa populations, as well as demonstrating that the Kulubnarti populations are part of that pattern. None of the populations are significantly different from one another.

Egypt↗
PubMed1981

Synthesis of analogues of acetylmethadol and methadol as potential narcotic antagonists.

The N-allyl and N-(cyclopropylmethyl) analogues of (-)-alpha-acetylmethadol and (-)-alpha-methadol have been synthesized and evaluated for opiate agonist and opiate antagonist activity. Both acetylmethadol analogues possessed weak analgesic activity in vivo tests for narcotic analgesia; the N-allyl analogue partially antagonized morphine-induced tail-flick analgesia. All four compounds possessed only opiate agonist-like activity as determined by in vitro studies measuring inhibition of [3H]naloxone binding to opiate receptors.

Animals↗
PubMedDate not supplied

Effects of protective knee bracing on speed and agility.

We evaluated the effects of prophylactic knee braces on athlete speed and agility, as well as brace tendency to migrate. Thirty college football players in full gear ran a 40-yard dash and a four-cone agility drill wearing braces on both knees or no brace (control). Braces included the DonJoy Legend, Breg Tradition, OMNI-AKS 101W, McDavid Knee Guard, and models 1 and 2 of the Air Armor Knee and Thigh Protection System. Brace migration and subjective measures were recorded after each trial. In the 40-yard dash, times using Air Armor 1 and OMNI did not differ significantly from control. Times with other braces were significantly slower. In the four-cone drill, only the Breg times were significantly slower than control. The Air Armor 1 and McDavid braces showed significantly less superior/inferior migration in the 40-yard dash than other braces. In the four-cone drill, the Air Armor 1 and 2 showed significantly less superior/inferior migration than other braces. These findings indicate that selected knee braces do not significantly reduce speed or agility. Braces showed a variable tendency to migrate, which could affect their protective function and athlete performance. This information will help athletes and coaches decide about knee-brace use during sports; studies are needed regarding whether braces protect against knee injury. This study does not constitute an endorsement of knee-brace use or efficacy.

Adolescent↗
PubMedDate not supplied

Dental field theory: an application to primate evolution.

A major complicating factor in using dental data in analyses of taxonomic and evolutionary problems is the existence of morphogenetic fields. Efforts are made to abstract tooth crown size morphogenetic fields of the orangutan. The utility of coefficients of variability and factor analysis, to this end, is presented. Resulting morphogenetic dental crown size fields are described and related to hominoid dental evolution.

Animals↗