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Biomedical subjects

R Mitchell

Publications and source records attributed to R Mitchell.

At least 253 records · Page 14Linked to original sources
PubMed1990

Computerised arthrotomography of primary anterior dislocation of the shoulder.

Computerised arthrotomography was performed on 33 patients four to six weeks after acute primary anterior dislocation of the shoulder. Seventeen patients were under, and 16 over 50 years of age. Damage to the anterior glenoidal labrum was seen in all the younger patients and in 75% of the older ones. A large redundant capsular pouch, seen in the older patients, was present in 35% of the younger ones, and a posterior humeral head defect was seen in 82% of the younger patients and only 50% of the older. Associated fractures were more common in the older patients, and a tear of the rotator cuff was demonstrated in 63% of the older patients and in none of the younger ones.

Adult↗
PubMed1990

The utilization of calcium soaps from animal fat by laying hens.

Ground wheat was employed as a carrier to evaluate the utilization by laying hens of animal fat, calcium soaps of fatty acids from animal fat (CS), and animal fat in the presence of 3.8% added calcium. Birds trained to consume their daily feed in two 1-h periods were fed ground wheat with 0, 3, 6, and 9% animal fat, CS, or 10% ground limestone and animal fat to provide 11 experimental diets. Animal fat and preformed CS were highly available to laying hens with total fatty acid availabilities of 100.2 +/- 1.2 (SE) and 99.2 +/- 3.6%, respectively, estimated by the regression of added fat on determined fat retentions. However, 3.8% calcium reduced animal-fat fatty acid availability to 86.3 +/- .7%. The true metabolizable energy of animal fat, as determined by regression from bomb-calorimetry data, was 9.63 +/- .58 kcal per g; a value of 9.36 kcal per g was obtained from fat-retention data [100.2% of the gross energy (GE) of 9.34 +/- .78 kcal per g]. With added limestone, the respective TME values were 9.36 +/- 1.30 kcal per g (regression) and 8.06 kcal per g (retention). The TME of the CS fatty acids was 7.20 +/- 1.05 kcal per g, estimated by regression; and the value calculated from CS fat retentions was 8.14 kcal per g, representing 99.2% of the GE (8.20 +/- .58 kcal per g). Discrepancies between calorimetric and fat-retention TME estimates represented animal-fat effects on wheat starch, fat, and amino-acid retentions.

Absorption↗
PubMed1989

Vascular endothelial growth factor: a new member of the platelet-derived growth factor gene family.

Using applications of the polymerase chain reaction (PCR) technique, cDNA clones have been isolated encoding bovine vascular endothelial growth factor (VEGF), a mitogen with specificity for vascular endothelial cells. Analysis of the clones indicates that VEGF can exist in two forms, probably due to alternative RNA splicing. The amino acid sequences predicted from the clones also show that VEGF shares homologies of about 21% and 24% respectively with the A and B chains of human platelet-derived growth factor (PDGF), and has complete conservation of the eight cysteine residues found in both mature PDGF chains. The homology is not reflected in function, however, since the cell types responsive to VEGF are distinct from those responsive to homo- and heterodimers of the PDGF chains.

Amino Acid Sequence↗
PubMed1989

The effect of some antiprostatic steroids upon cortisol production by guinea-pig adrenal cells stimulated by ACTH.

The antiprostatic steroids 6-methylene-4-pregnene-3,20-dione (6-MP) (I), 17-alpha-acetoxy-6, 16-dimethylene-4-pregnene-3,20-dione (II), and melengestrol acetate (MGA) (III) were incubated with guinea-pig adrenal cells, both alone and maximally stimulated with ACTH. Cortisol output was then measured by RIA. Increased cortisol-like secretion was obtained with 6-MP in the absence of ACTH. In the presence of ACTH, cortisol-like steroid secretion was the sum of that seen with ACTH and 6-MP alone. It follows that 6-MP stimulates in vitro a cortisol-like steroid cross reacting with the cortisol antibody by a mechanism that by-passes ACTH. Steroid (II) weakly inhibited cortisol output. MGA, in contrast, proved to be a strong inhibitor of cortisol output (ID50 of 2.3 mumol/l). Its site of action was established by adding it to adrenal cells incubated with precursor steroids on the cortisol pathway. Conversion of 3 beta-hydroxysteroids to cortisol was inhibited whereas conversion of 3-keto steroids was not affected. It follows that MGA inhibits 3 beta-hydroxysteroid dehydrogenase.

3-Hydroxysteroid Dehydrogenases↗
PubMed1989

The elimination of cross-infection in dental practice--a 5-year follow-up.

A survey in 1983 showed that 16% of general dental practitioners in the Lothian Region wore operating gloves when treating patients; 9% wore them continually and 7% only when performing dento-alveolar surgery. Twelve per cent replied that they would not consider wearing operating gloves and 72% stated that they might consider their use. A similar survey has now been completed 5 years later, involving practitioners in the Lothian and Borders regions. This shows that 163 (97%) of the 168 practitioners who replied now wear operating gloves; 51% restrict their use to the treatment of 'potentially infectious patients' and dento-alveolar surgery; 46% wear them continually. The main objections given to wearing gloves continually were loss of tactile sensation (67%) and cost (13%). The most difficult task to perform wearing gloves was root canal therapy (56%). The majority of practitioners (84%) believed that gloves reduced the dangers of cross-infection. The methods stated to be available for instrument sterilisation in 99.5% of practices were acceptable. This paper proposes that to eliminate cross-infection and protect the dental practitioner, operating gloves should be worn when treating all patients.

Attitude to Health↗
PubMed1989

Novel ligands for the affinity labelling of luteinizing hormone releasing hormone receptors.

A number of novel luteinizing hormone releasing hormone (LHRH) analogues incorporating biotin together with potential covalent attachment sites have been synthesized. Those based on the des-Gly10-[D-Lys6]-LHRH ethylamide peptide backbone resulted in the most useful characteristics of binding to the LHRH receptor in rat anterior pituitary gland membranes. Of these, des-Gly10-[biotinyl-aminoethylglycyl-D-Lys6]-LHRH ethylamide (XBAL) gave the best specific: non-specific binding ratio, with 44 +/- 6% (+/- S.E.M.) of total binding being specific with a Kd of 131 +/- 16 pM (+/- S.E.M., n = 4) as determined by Scatchard analysis. Two methods have been used to covalently crosslink these analogues with the LHRH receptor; photoaffinity labelling and the use of homobifunctional N-hydroxysuccinimide ester crosslinkers. The photoaffinity analogues gave poor specific: non-specific binding ratios. Of the chemical crosslinkers tested, ethylene glycolbis(succinimidylsuccinate) (EGS) was found to be the most efficient at covalently linking the 125I-XBAL bound to the LHRH receptor site. At an EGS concentration of 5 mM, 23 +/- 3% (+/- S.E.M.) of the specific binding of 125I-XBAL was covalently crosslinked.

Affinity Labels↗
PubMed1988

Heterogeneous effects of serotonin in the dorsal horn of rat: the involvement of 5-HT1 receptor subtypes.

The effect of ionophoretically applied serotonin (5-HT) was tested on cutaneous sensory responses of multireceptive dorsal horn neurones in the anaesthetized rat. Three types of 5-HT action were discerned: selective inhibition of nociceptive responses (10/18 cells), non-selective inhibition of responses to both noxious and innocuous stimuli as well as to excitatory amino acids (4/18 cells) and non-selective excitation of evoked responses (1/18 cells). A few cells (3/18) were unaffected by 5-HT. The use of agonists, shown to discriminate between subtypes of 5-HT1 receptor revealed that a 5-HT1A receptor agonist mimicked the non-selective effects of 5-HT, whereas a 5-HT1B receptor agonist mimicked the selective antinociceptive effects of 5-HT. A 5-HT2 receptor agonist, in contrast, was without effect. Both the selective and the non-selective effects were reversed by a 5-HT1 receptor antagonist, but not a 5-HT2 antagonist.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1988

The influence of opioid receptor subtypes on the processing of nociceptive inputs in the spinal dorsal horn of the cat.

Extracellular recordings were made of the cutaneous sensory responses of spinocervical tract (SCT) neurones in the lumbar dorsal horn of anaesthetised and paralysed cats. All of the neurones studied were multireceptive, showing excitatory responses to both innocuous and noxious (thermal and when tested, mechanical) stimuli applied to their cutaneous receptive fields on the ipsilateral hindlimb. The effects of iontophoretically applied opioids were studied on a regular cycle of responses to these cutaneous stimuli and also to D.L-homocysteic acid (DLH). In the first series of experiments, drugs were applied in the vicinity of the SCT neurones. The kappa-receptor agonists dynorphin A(1-13) and U50488H, but not dynorphin A(2-13), the mu-agonist DAGO, or the delta-agonist DADL, caused a selective reduction of the nociceptive responses of the neurones. The corresponding responses to innocuous stimuli or to DLH, and spontaneous activity were unaffected. In the second series of experiments, drugs were applied from a second electrode placed in the region of the substantia gelatinosa directly dorsal to the tip of the recording electrode. Under these conditions, the mu-receptor agonist DAGO, but not the kappa-agonist dynorphin A(1-13) or the delta-agonists DADL, DSLET or DLPEN, showed a selective antinociceptive effect. In both series, the antinociceptive effects of the opioids were readily reversed by iontophoretically applied naloxone. The effect of dynorphin A(1-13) applied close to SCT neurones, but not that of DAGO applied in the region of the substantia gelatinosa, was reversed by the alpha 2-adrenoceptor antagonist, idazoxan. The results indicate that both mu- and kappa-opioid receptors (at anatomically distinct sites) can participate in the selective antinociceptive influence that opioids can exert over somatosensory information ascending to supraspinal levels. The antagonism of kappa-receptor-mediated antinociception by idazoxan is consistent with an interaction of opioid and noradrenaline influences at the level of the dorsal horn.

Animals↗
PubMed1988

Antibody that blocks stimulation of cortisol secretion by adrenocorticotrophic hormone in Addison's disease.

To investigate whether Addison's disease may in some cases be due to the blocking of adrenocorticotrophic hormone's action at the adrenal cortex by antibodies IgG isolated from a woman with Addison's disease associated with the autoimmune polyglandular syndrome type I was studied. Its effects on guinea pig adrenal cells in vitro were investigated and compared with those of IgG from three normal subjects and IgG obtained commercially. IgG from the patient inhibited the stimulation of cortisol secretion by adrenocorticotrophic hormone by 77 (SD 2)% and 57 (12)% at concentrations of 0.5 and 0.05 g/l, respectively; IgG prepared five months after she had started treatment with replacement steroids inhibited cortisol secretion by 74 (1)% (0.5 g/l) and 51 (15)% (0.05 g/l). The other IgGs had no inhibitory effects. The IgG from the patient and that obtained commercially did not inhibit the stimulation of cortisol secretion by dibutyryl cyclic adenosine monophosphate or precursors of cortisol. None of the IgGs bound to adrenocorticotrophic hormone. These results suggest that the IgG from the patient acted against the receptor for adrenocorticotrophic hormone, and its presence may explain the patient's raised concentrations of adrenocorticotrophic hormone, failure to respond to exogenous adrenocorticotrophic hormone, and normal basal cortisol concentrations. Addison's disease may thus in some instances be a receptor antibody disease.

Addison Disease↗
PubMed1988

Expression of human basic fibroblast growth factor cDNA in baby hamster kidney-derived cells results in autonomous cell growth.

Growth factor over-production by responsive cells might contribute to their autonomous proliferation as well as their acquisition of a transformed phenotype in culture. Basic fibroblast growth factor (bFGF) has been shown to induce transient changes in cell behavior that resemble those encountered in transformed cells. In addition, several types of human tumor cells have been shown to produce bFGF. To determine directly the role that bFGF might play in the induction of the transformed phenotype, we have introduced a human bFGF cDNA expression vector into baby hamster kidney-derived (BHK-21) fibroblasts. One of the BHK transfectants, termed clone 19, expresses the bFGF mRNA and produces biologically active bFGF that accumulates to a high concentration inside the cells. These properties correlate with the ability of the cells to grow in serum-free medium without the addition of exogenous bFGF. Clone 19 cells also proliferated in soft agar, indicating that constitutive expression of the bFGF gene results in a loss of anchorage-dependent growth.

Animals↗
PubMed1988

LKE red cell antigen and its relationship to P1 and Pk: serological study of a large family.

The fourth example of human anti-LKE was identified in the serum of an antenatal patient. Study of the red cells of the proband and her family confirmed the recessive inheritance of the LKE- phenotype. The blood groups of the family confirmed that Pk expression is greater on cells from LKE- members than on those from LKE+ members. In this family, the expression of LKE varied with the P1 phenotype. LKE- individuals occurred with an incidence of 0.0017 in the donor population of the Glasgow and West of Scotland Region.

Blood Group Antigens↗