PubMed Health⌕ Search

Biomedical subjects

R N Atkinson

Publications and source records attributed to R N Atkinson.

11 recordsLinked to original sources
PubMed2004

Patellar 'entry' feature: a new arthroscopic anatomic finding.

The purpose of this paper is to report a frequently noticed anatomical feature on the soft synovial floor of the suprapatellar pouch in the knee, which has not been reported before. Four hundred and fifty-seven consecutive knee arthroscopies were carried out. The patellar entry feature was present in 294 and not noticed in 163. There was not a concurrent control group. During arthroscopy the presence or absence of the patellar entry feature was noted and entered on a database consecutively and prospectively. All arthroscopies were carried out by the senior author. The ages of the patients undergoing arthroscopy ranged from 8 to 96 years with a mean age of 39.4 years. Out of 457 there were 318 males and 139 females. Where the patellar entry feature was found, there was an average of 40% female; where there was not, there was an average of 27% female. The patellofemoral articulation has been a focus of interest mainly because of the poorly understood and extremely common anterior knee pain syndrome (AKPS). We hypothesise that the patellar entry feature is the area where the patella rests, with the knee in full extension and the quadriceps relaxed and is thus the starting point before flexion is initiated.

Adolescent↗
PubMed2001

Identification of the first trans-(3R,4R)- dimethyl-4-(3-hydroxyphenyl)piperidine derivative to possess highly potent and selective opioid kappa receptor antagonist activity.

A structurally novel opioid kappa receptor selective ligand has been identified. This compound, (3R)-7-hydroxy-N-((1S)-1-[[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl]-2-methylpropyl)-1,2,3,4-tetrahydro-3-isoquinolinecarboxamide (JDTic, 10) demonstrated high affinity for the kappa receptor in the binding assay (kappa K(i) = 0.3 nM) and highly potent and selective kappa antagonism in the [(35)S]GTP-gamma-S assay using cloned opioid receptors (kappa K(i) = 0.006 nM, mu/kappa ratio = 570, delta/kappa ratio > 16600).

Animals↗
PubMed2001

Factors influencing agonist potency and selectivity for the opioid delta receptor are revealed in structure-activity relationship studies of the 4-[(N-substituted-4-piperidinyl)arylamino]-N,N-diethylbenzamides.

A study of the effect of transposition of the internal nitrogen atom for the adjacent benzylic carbon atom in delta-selective agonists such as BW373U86 (1) and SNC-80 (2) has been undertaken. It was shown that high-affinity, fully efficacious, and delta opioid receptor-selective compounds can be obtained from this transposition. In addition to the N,N-diethylamido group needed as the delta address, the structural features identified to promote delta receptor affinity in the set of compounds studied included a cis relative stereochemistry between the 3- and 4-substituents in the piperidine ring, a trans-crotyl or allyl substituent on the basic nitrogen, the lack of a 2-methyl group in the piperidine ring, and either no substitution or hydroxyl substitution in the aryl ring not substituted with the N,N-diethylamido group. Structural features found to be important for mu affinity include hydroxyl substitution in the aryl ring, the presence of a 2-methyl group in a cis relative relationship to the 4-amino group as well as N-substituents such as cyclopropylmethyl. It was also determined that mu receptor affinity could be increased while maintaining delta receptor affinity, especially when hydroxyl-substituted compounds are considered. Additionally, it was discovered that the somewhat lower mu/delta selectivities observed for the piperidine compounds relative to the piperazine-based ligands appear to arise as a consequence of the carbon-nitrogen transposition which imparts an overall lower delta and higher mu affinity to the piperidine-based ligands. This higher affinity for the mu receptor, apparently intrinsic to the piperidine-based compounds, suggests that ligands of this class will more easily be converted to mu/delta combination agonists compared to the piperazine ligands such as 1. This is particularly important since analogues of 1, which show both mu- and delta-type activity, are now recognized as important for their strong analgesia and cross-canceling of many of the side effects found in agonists operating exclusively from either the delta or mu opioid receptor.

Animals↗
PubMed2000

4-[(8-Alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-diethylbenzamides: high affinity, selective ligands for the delta opioid receptor illustrate factors important to antagonist activity.

The tropane derived compounds, 4-[(8-alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-d iethylbenzamides (5a-d), were synthesized and found to have high affinity and selectivity for the delta receptor. Compounds 5a-d are structurally similar to the full agonist (-)-RTI-5989-54 (3); yet, efficacy studies for compounds in this series (5a-d) reveal greatly diminished agonist activity as well as antagonism not found in piperidine-based compounds like 3.

Benzamides↗
PubMed1999

Optically pure (-)-4-[(N-allyl-3-methyl-4-piperidinyl)phenyl-amino]-N,N-diethylbenzami de displays selective binding and full agonist activity for the delta opioid receptor.

The optical isomers of 4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide+ ++ (3) have been prepared and tested in both binding and functional assays. The data show that (-)-3 is responsible for the delta opioid activity demonstrated by the racemic material. This compound displays a binding affinity of 5.5 nM for the delta opioid receptor as well as a 470-fold delta versus mu selectivity. Importantly, (-)-3 is a full agonist at the delta receptor in comparison with SNC-80 (2). Taken together, the data suggest that (-)-3 behaves more like the prototypical delta agonists, BW373U86 or SNC-80, and less like the peptidomimetic compound SL-3111 (5).

Benzamides↗
PubMed1999

Guanidine-substituted imidazoles as inhibitors of nitric oxide synthase.

Guanidine-substituted imidazoles were prepared and evaluated as inhibitors of the three isoforms of nitric oxide synthase. These results identify a new 2-substituted imidazole as an isoform selective inhibitor and illustrate the possible importance of the L-arginine side chain in selective isoform recognition.

Enzyme Inhibitors↗
PubMed1999

Synthesis and evaluation of new sulfur-containing L-arginine-derived inhibitors of nitric oxide synthase.

A series of compounds (7, 8, 10-17, 23) containing new functional groups derived by the combination of the substrate, intermediate, product, and known inhibitors of nitric oxide synthase (NOS) were prepared and evaluated against NOS. While none of the compounds assayed acted as a nitric oxide-producing substrate, the sulfur-containing arginine derivatives 10-12 were competitive inhibitors of iNOS with Ki's of 202, 7, and 58 microM, respectively. Compound 11 demonstrated the greatest potency against NOS-mediated citrulline formation for each of the three isoforms with IC50's of 6. 7, 19.7, and 13 microM for nNOS, eNOS, and iNOS, respectively. Compounds 10-12 each demonstrated a slight selectivity for inhibition of the neuronal isoform compared to the endothelial and inducible isoforms. These compounds also influenced the NADPH oxidase activity and heme iron spin state in a manner similar to structurally related compounds. Compound 10, a thiocarbonyl-containing compound, decreased the NADPH oxidase activity of the enzyme (EC50 = 190 microM) and shifted the heme iron spin state toward a low-spin configuration, similar to that of L-thiocitrulline. Compounds 11 and 12, S-alkylthiocitrulline derivatives, decreased the NADPH oxidase activity of the enzyme (EC50 = 6.6 and 180 microM, respectively) and shifted the heme iron spin state toward a high-spin configuration, similar to that of L-S-methylisothiocitrulline. Carbonyl-containing amino acid (7, 8, 23) and non-amino acid (13-17) analogues did not interact well with the enzyme.

Arginine↗
PubMed1992

Percutaneous Kirschner wire stabilisation following closed reduction of Colles' fractures.

32 consecutive unstable Colles' fractures were treated by closed reduction and percutaneous Kirschner wire stabilisation through the radial styloid, followed by a below-elbow cast. Radiological assessment was made at five stages of treatment: at the time of the fracture, immediately after operation, after two weeks, after six weeks and a final review at an average period of 15.9 months. Functional assessment was made at the final review. Only three fractures developed secondary displacement, which was due to the wrong placement of the Kirschner wire. There were no complications.

Adult↗
PubMed1984

Internal fixation of peritrochanteric fractures of the femur with the Harris condylocephalic nail.

Thirty patients in whom a peritrochanteric fracture of the femur was stabilized with a Harris intramedullary nail were studied retrospectively. The study showed an initially high complication rate and highlighted points of technique and selection which have led to improved results. In appropriate cases, this procedure is a fast, minimally traumatic, and secure method of internal fixation of peritrochanteric fractures.

Age Factors↗
PubMed1978

Bone scintigraphy in discitis and related disorders in children.

Thirty-nine children with suspected pathology involving the vertebral column were investigated haematologically, radiographically, and by bone scintigraphy using technetium 99M pyrophosphate. Fifteen children were shown to have inflammatory disease of the vertebrae. A further six suffered from Scheuermann's disease, two from benign tumours, and the remainder from miscellaneous diseases not specifically involving bony pathology. The nuclide scan was abnormal in all cases of discitis and osteomyelitis, and in the two tumours. All of the other conditions were associated with a normal bone scan. This finding is of considerable diagnostic importance, and leads support to the theory that discitis is due to bacterial infection.

Adolescent↗