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Biomedical subjects

R Jones

Publications and source records attributed to R Jones.

At least 991 records · Page 55Linked to original sources
PubMed1977

Regression of arteriosclerotic lesions in rhesus monkey aortas after regression diet. Scanning and transmission electron microscope observations of the endothelium.

Scanning and transmission microscopy were used to study aortic intima atherosclerotic lesions in Rhesus monkeys during both progression and regression phases. Scanning micrographs of severely atherosclerotic lesions showed areas of disjunctive endothelium and discontinuous basement membranes, frequently accompanied by red blood cells and other circulating elements adhering to the surface. Transmission micrographs also showed occasional areas of endothelial cell damage and loss with lipid-laden smooth muscle cells and foam cells beneath. Regressed lesions (affected by low-fat, low-cholesterol diet with or without cholestyramine) showed endothelial changes suggestive of reparative processes. Scanning micrographs showed flattened residual lesions with continous endothelial lining, while transmission microscopy disclosed interdigitated intercellular tight junctions and frequently reduplicated basement membranes.

Animals↗
PubMed1977

Low back injury in sport.

Low back injuries are shown to present a serious hazard to sportsmen and women, and may lead to long-term disability in relation to their sport. Training methods, particularly weight training, led to many of the injuries and it is recommended that personnel involved in training become more aware of these dangers. Spondylolysis was found in 18% of cases and it is suggested that the full investigation of low back pain in a sportsman is incomplete until this lesion has been excluded.

Adolescent↗
PubMed1977

Anomalies of disparity detection in the human visual system.

1. Oculomotor and psychophysical depth responses were investigated in thirty individuals by use of briefly exposed disparities in the range from 0-6 to 4-6 degrees (1-8 centrads). 2. The results substantiate a previous finding which reported the common occurrence of specific types of stereoanomalies within a sample from the normal population. However, arguments are presented to suggest that these forms of stereoanomalies are limited to coarse stereopsis and spare mechanisms concerned with fine disparity, high resolution stereopsis. 3. A relatively high proportion of individuals were found to manifest deficiencies of vergence eye movement under these stimulus conditions. These vergence-anomalies are characterized by a marked reduction, or absence, of neither convergent or divergent eye movements to briefly exposed stimuli. 4. The vergence-anomaly is not detrimental under normal seeing conditions since it can be present in persons with adequate binocular vision and normal fine stereopsis. 5. The presence of vergence-anomaly was always associated with the occurrence of stereoanomaly; however, the converse was not true. 6. The results are taken as evidence to show how disparity information is organized prior to its influence upon the processes of coarse stereopsis and vergence initiation.

Depth Perception↗
PubMed1977

Toxicity of exogenous fatty acid peroxides towards spermatozoa.

The toxicity of unsaturated fatty acids towards spermatozoa was shown to be directly related to their degree of peroxidation. The toxicity was manifested by an immediate arrest of motility and irreversible loss of respiratory and fructolytic activity. Repeated washing of spermatozoa, or the addition of fructose, lactate, or ATP, failed to restore these functions. The structural damage incurred as a result of the fatty acid peroxides was particularly evident in the acrosomal region. Partial protection from the adverse effects of these peroxides was provided by prior treatment of spermatozoa with dialysed egg yolk or milk, but tocopherol, albumin and mercapto-ethanol were ineffective. It is suggested that lipid peroxides or their degradation products, whether introduced exogenously or derived from the peroxidation of endogenous phospholipids in semen, constitute a potential hazard to the functional integrity of spermatozoa.

Animals↗
PubMed1977

Damage to ram spermatozoa by peroxidation of endogenous phospholipids.

We examined the damaging effects on spermatozoa of endogenous phospholipid peroxidation brought about by aerobic incubation at 37 degrees C in the presence of 0-5 mM-ascorbic acid and 0-5 mM-FeSO4. As well as becoming immotile, such peroxidized spermatozoa also lost, through leakage, certain intracellular enzymes into the surrounding medium, on a scale resembling that produced by cold shocking non-peroxidized spermatozoa. Morphological observations revealed that peroxidation damaged the plasma membrane, particularly in the region of the acrosome. Further experiments showed that lipid peroxidation irreversibly abolished the fructolytic and respiratory activity of spermatozoa. The susceptibility of spermatozoa to peroxidation was greater when the cells were damaged before incubation with ascorbic acid and FeSO4. To some extent, peroxidation could be prevented, but not reversed, by the addition to sperm suspensions of dialysed egg yolk or dialysed bull seminal plasma. However, dialysed seminal plasma from ram, stallion or man had no protective effect.

Animals↗
PubMed1977

Effects of testosterone, testosterone metabolites and anti-androgens on the function of the male accessory glands in the rabbit and rat.

The androgenic potencies of testosterone, 5alpha-dihydrotestosterone, 5alpha-androstane-3alpha,17beta-diol and 5alpha-androstane-3beta,17beta-diol towards the prostate, glandula seminalis+glandula vesicularis, ampullae and epididymis were evaluated after administration to castrated rabbits. The influence of cyproterone acetate, stilboestrol and medrogestone on accessory gland function was also investigated in rabbits and rats. In the rabbit it was found that the minimum dose of testosterone propionate that would maintain the function of all accessroy glands at normal levels was approximately 200 microgram/animal/day. Higher levels of testosterone propionate overstimulated the function of the prostate, glandula seminalis+glandula vesicularis and ampullae, but did not affect the epidiymis. Whereas testosterone propionate and 5alpha-dihydrotestosterone propionate were essentially equipotent in their capcity to support growth and secretory activity and stimulated all the accessory glands, 5alpha-androstane-3alpha,17beta-diol dipropionate had a pronounced differential effect; it was considerably more potent than testosterone propionate in promoting secretion in the prostate, but was ineffective in maintaining the function of the epididymis. 5alpha-Androstane-3beta,17beta-diol dipropionate was the weakest androgen tested. Evidence also indicated that the potency of a steroid can depend on whether it is administered as its free or esterified form. Cyproterone acetate suppressed fructose secretion in the prostate of the rabbit but had no adverse effects on the function of the epididymis in either the rabbit or rat. Stilboestrol was the most potent anti-androgen tested and medrogestone the least effective.

Androgen Antagonists↗
PubMed1977

Human effects.

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Animals↗
PubMed1977

Efficacy, side-effects, plasma and blood levels of maprotiline (Ludiomil).

Two trials of maprotiline (Ludiomil) were performed in general practice. In the first study depressed patients were given either 75 mg of maprotiline in a single dose or 25 mg three times daily. Assessments of the severity of depression and of side-effects were made initially and following 1, 2 and 4 weeks' treatment. At each assessment measurements of plasma levels of maprotiline were made. A second trial was performed in which some patients receiving 75 mg single dose of maprotiline had whole blood levels of maprotiline assayed. Steady-state levels of maprotiline were achieved after one week but these levels showed considerable individual variability. No clear correlation emerged between clinical response, side-effects and plasma or blood levels. Some of the factors which may be responsible are discussed.

Adult↗
PubMed1976

In vitro incorporation of isomeric cis-octadecenoic acids by rat liver mitochondria.

The metabolic fate of positional isomers of cis-octadecenoic acids was compared to that of oleic acid, elaidic acid and stearic acid in rat liver mitochondria. The positional isomers as well as elaidic acid and stearic acid were labelled with 3H and they were incubated in pairs with [1-14C]oleic acid. 3H/14C ratios were determined for the administered mixtures and for the isolated lipid classes. The results suggested that all isomers were readily incorporated into the membraneous structure of mitochondria. Those with the double bond in the middle of the acyl chain resembled oleic acid and they were preferentially incorporated in cholesterol esters, triacylglycerols and in the 2-position of triacylglycerols and of phosphatidylcholines. Those with the double bond away from the middle of the chain were metabolically distinct from oleic acid and behaved like trans fatty acids. They were rapidly taken up by mitochondria. They were preferentially incorporated in phospholipids and they occupied the 1-position in phosphatidylcholines and the 1- and 3-positions in triacylglycerols.

Animals↗
PubMed1976

The effect of muscle extracts on the contracture response of skeletal muscle to acetylcholine.

Preincubation of normal rat soleus muscles in vitro with homogenates prepared from mixed leg muscles which had been denervated 4 days previously resulted in an increase in the contracture response to acetylcholine. After 30 min incubation a 1.5-fold increase was observed. Homogenates of normally innervated muscles did not increase the response. The active principles of the denervated muscles were found to reside in the "cytosol" fraction. An approximately 2-fold increase was observed upon incubation with the cytosol for 30 min; incubation for longer periods resulted in a subsequent decrease in the response. The effect of the denervated muscle cytosol was concentration-dependent and heat-labile. Normal muscle cytosol also increased the soleus muscle response to acetylcholine but this fraction was less effective than denervated muscle cytosol. The response of control muscles incubated in Krebs-Henseleit solution was found to decrease with time. Commercially obtained phospholipases C and D increased the response of normal soleus muscles approximatley 2-fold. Phospholipase A, lipase, trypsin, collagenase and a bacterial protease had no effect, lysozyme produced a small but consistent increase in the response to acetylcholine.

Acetylcholine↗
PubMed1976

Interactions of the lanthanide- and hapten-binding sites in the Fv fragment from the myeloma protein MOPC 315.

1. The interactions of lanthanide metals and dinitrophenyl spin-label haptens with the Fv fragment of the mouse myeloma protein MOPC 315 were investigated by the techniques of fluorescence, e.s.r. (electron spin resonance) and high-resolution n.m.r. (nuclear magnetic resonance). 2. The protein fluorescence of Fv fragment at 340nm is quenched by the haptens (fluorescence enhancement, epsilon=0.15) and enhanced by Gd(III) (epsilon=1.14) and other lanthanides. The binding of the haptens studied here is insensitive to pH in the range 5.5-7.0 (dissociation constant KH=0.3-1.0 muM) and shows 1:1 stoicheiometry. The binding of Gd(III) also shows 1:1 stoicheiometry, but is pH-dependent; the binding constant (KM) varies from 10 muM at pH7.0 to 700 muM at pH4.8. La(III) binding is less sensitive to pH. The pH-dependences of the metal-binding constants imply that a group in the protein with pKa greater than or equal to 6.2 is involved in the binding, and probably also other groups with lower pKa values. 3. The apparent binding of the haptens is weakened about 20-fold by Gd(III), and vice versa. An equilibrium scheme involving a ternary complex with an interaction between the two binding sites is derived in Appendix I to explain the experimental results at two pH values. 4. Time-dependent fluorescence changes are observed in the presence of Gd(III) at pH5.5. A two-state kinetic scheme involving a 'slow' conformational change in the Fv fragment is derived in Appendix II to explain this time-dependence. This scheme is consistent with the antagonistic equilibrium behaviour. 5. The e.s.r. changes in the spin-label haptens on binding to Fv fragment and on the subsequent addition of lanthanides are consistent with the binding scheme for haptens and lanthanides proposed from the fluorescence studies. A difference between the limiting quenching of the e.s.r. signal from the bound haptens in the presence of saturating concentrations of Gd(III) and La(III) is attributed to dipolar interactions between bound Gd(III) and the nitroxide moiety of the bound hapten. The residual quenching with Gd(III) allows an estimate of 1.2nm to be made for the distance between the two paramagnetic centres. 6. The 270 MHz proton difference spectrum of the Fv fragment resulting from the addition of La(III) suggests that any metal-induced conformational changes are small and involve relatively few amino acid residues on the Fv fragment...

Animals↗