Heart developmental biology. Introduction.
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Animals↗
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A2E, a fluorophore of RPE lipofuscin: can it cause RPE degeneration?
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Animals↗
Synthetic hepatitis B surface antigen peptide vaccine.
A synthetic hepatitis B surface antigen (HBsAg) peptide was prepared containing amino acid residues 122-137 of the major HBsAg polypeptide. This peptide was cyclized by the introduction of an intrachain disulfide bond between cysteine residues at positions 124 and 137 because previous studies had shown that intact disulfide bonds are critical for maintenance of HBsAg activity. An anti-HBs response was produced in mice by free peptide entrapped in liposomes. However, the immunogenicity was enhanced by aggregation into micelles, and by coupling to tetanus toxoid. Analysis of the peptide with a panel of monoclonal antibodies showed that peptide 122-137 contained a conformation (discontinuous) group a epitope and a sequential (continuous) subgroup y epitope. In addition, the cyclic peptide inhibited a human anti-HBs idiotype-anti-idiotype reaction with specificity for group a determinant(s). The potential for synthetic peptides for hepatitis B virus vaccine development is discussed.
Animals↗
The role of epithelium in the responsiveness of the bronchi to stimuli.
Airway narrowing in response to different modes of stimuli was measured using a perfused bronchial segment. Acetylcholine, carbachol, histamine, high [K+] and vanadate perfused through the lumen gave small responses as shown by the reduction in flow, but fully constricted the airway when applied to the outside. ACh was 29 times more sensitive on the outside. When the epithelium was removed airway narrowing by these stimuli was increased to equal that on the outside. It was concluded that the role of the epithelia as a barrier is all important. Evidence for an EpDIF released by the epithelium could not be obtained.
Acetylcholine↗
Airway diameter determines flow-resistance and sensitivity to contractile mediators in perfused bronchial segments.
To study airway reactivity, flow-resistance to carbachol and histamine was measured in perfused bronchial segments. Small-bore airways were more sensitive, flow was reduced to zero and resistance rose very steeply due to mucosal folding while in large-bore airways maximum flow reduction was 50% and resistance increased sigmoidly. Thus the internal diameter of an airway is a crucial determinant of narrowing.
Airway Resistance↗
Human lens nuclear colour matching and brunescence grading in vivo.
The nuclear colour of in vivo human lenses has been investigated by means of a colour matching technique, using 'Munsell' colour samples. Observations covered an extended age range, and included all degrees of nuclear pigmentation. A positive correlation was noted between increasing nuclear pigmentation and age. The colour matching data generated was used as a basis for establishing a system of nuclear brunescence grading. The system of grading consists of a Grade 0 for absence of brunescence, and Grade 1 to Grade 5 for increasing brunescence. The 'Munsell' notation for samples representing these grades are: Grade 0 (5GY 6/1), Grade 1 (5Y 7/4), Grade 2 (2.5Y 7/8), Grade 3 (7.5YR 6/8), Grade 4 (5YR 4/6), and Grade 5 (2.5YR 2.5/2). Assessments of both inter- and intra-observer variability in the use of the derived scale have shown the new colour grading system to be reliable. The measure is simple to use during biomicroscopic slit-lamp examination of the lens, and has the potential for routine clinical application as well as for use in clinical trials where detailed documentation of lens morphology is required. The new colour scale may be used either as an isolated measure, or as part of a battery of lens measures in the Oxford Clinical Cataract Classification and Grading system.
Aging↗
Inter-observer and intra-observer variability of the Oxford clinical cataract classification and grading system.
Intra-observer (within observers) and inter-observer (between observers) variability of the Oxford Clinical Cataract Classification and Grading System were studied. Twenty cataracts were examined and scored independently by four observers. On a separate occasion two of the observers repeated the assessments of the same cataracts in the absence of information from the initial observations. The chance corrected and weighted kappa statistics for observer agreement, both for inter-observer and intra-observer variability demonstrated satisfactory repeatability of the cataract grading system. The overall intra-observer mean weighted kappa was kappa w = +0.68 (range SE kappa = 0.012-0.052) and the overall inter-observer mean weighted kappa was kappa w = +0.55 (range SE kappa = 0.011-0.043).
Cataract↗
Methods for evaluation of lens changes.
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Cataract↗
The Oxford Clinical Cataract Classification and Grading System.
A composite slit-lamp based system for the clinical classification and grading of cataract is described. Cataract features are classified morphologically, and individual features are graded by comparison with standard diagrams mounted adjacent to the slit-lamp. Attention has been paid to relevant aspects of measurement theory, with equal interval steps between the grades. The image degrading effect of the cataract is assessed using a 'resolution target projection ophthalmoscope'. The method may be used in conjunction with photographic and image analysing techniques.
Cataract↗
The small intestine in experimental diabetes: cellular adaptation in crypts and villi at different longitudinal sites.
Intestinal adaptation at the cellular level was examined in groups of streptozotocin-diabetic and age-matched control rats. Small intestines were removed and divided into four segments of roughly equal length. For each segment, epithelial volume, villous and microvillous surface areas and the mean volumes of epithelial cells in crypts and villi were estimated. From these data, we were able to estimate total numbers of epithelial cells in crypts and villi, assess adaptation at the level of the average cell and explore variation along the crypt-villus axis, between segments and between groups. Whilst the villus:crypt cell ratio did not change, diabetic animals contained about 80% more epithelial cells than control rats. The morphophenotype of villous epithelial cells (represented by nuclear volume, cell height, area and volume, and number and surface area of microvilli) was basically the same as that in controls. By contrast, crypt cells and their nuclei were 40-50% bigger in diabetic rats. Significant differences between segments were confined to the numbers and sizes of crypt cells and their nuclei. We conclude that experimental diabetes leads to both proliferative and hypertrophic responses within crypts. Crypt cells become fatter but not taller. Crypt hyperplasia is accompanied by an equiproportionate increase in villous epithelial cells, but these are of essentially normal morphophenotype.
Adaptation, Physiological↗
Number and ultrastructure of epithelial cells in crypts and villi along the streptozotocin-diabetic small intestine: a quantitative study on the effects of insulin and aldose reductase inhibition.
This study has quantified the effects of insulin treatment with and without aldose reductase inhibitor (ponalrestat) on intestinal epithelial cell morphology in streptozotocin-diabetic rats. Epithelial volumes, villous and microvillous surface areas and mean volumes of cells (and their nuclei) in crypts and villi were estimated in each of four segments and in the entire intestine. We derived total numbers of cells, quantified the ultrastructural features of average cells and explored variation along the intestine and between experimental groups. In crypts, insulin and ponalrestat had significant effects on cell number (reduced towards normal values) and size (volume and apex area increased beyond normal values). There were interaction effects between insulin and ponalrestat for cell volume and apex area (insulin producing more exaggerated effects when given without ponalrestat). On villi, insulin and ponalrestat returned cell numbers towards normal values but neither treatment normalised cell size or the number and area of microvilli per cell. Indeed, ponalrestat increased microvillous number and area beyond values found in untreated diabetic animals. Again, there were interaction effects between insulin and ponalrestat. Patterns of segmental variation seen in crypts of normal rats (values tending to be higher in proximal or mid-intestinal regions) were not preserved, and only some of the segmental differences seen on villi (higher values at proximal or mid-intestinal sites) were maintained during therapy. Apart from reducing the abnormally high numbers of cells in untreated diabetic rats, these results show that insulin and ponalrestat treatment fail to restitute epithelial cell morphology in the small intestines of experimental diabetic rats.
Animals↗
The acuityscope: a resolution test target projection ophthalmoscope.
The Acuityscope projects an image of a three bar resolution test target onto the patient's retina, where it is viewed and read by an observer. The test target consists of a series of three bar targets varying in size on a logarithmic scale. Individual targets are identified in the projected image by Bailey-Lovie log visual acuity equivalents. The projected image includes only those target sizes which are useful for estimating visual acuity. The Acuityscope is used for assessing the quality of retinal image formation, and is thus able to differentiate between poor visual acuity due to image degradation, (e.g. cataract or corneal disease) and poor visual acuity due to image handling defects (e.g. retinal or optic nerve disease). The use of the instrument is relevant to both clinical situations (e.g. pre-operative assessment of opacification of optical media) and experimental situations (e.g. clinical trials).
Equipment Design↗
The selection for mutants in Drosophila melanogaster hypersensitive to alpha-methyl dopa, a dopa decarboxylase inhibitor.
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Animals↗
Characterisation of missense mutations in the Act88F gene of Drosophila melanogaster.
We have created missense mutations in the indirect flight muscle (IFM)-specific Act88F actin gene of Drosophila melanogaster by random in vitro mutagenesis. Following P element-mediated transformation into wild-type flies and subsequent transfer of the inserts into Act88F null strains, the effects of the actin mutants on the structure and function of the IFMs were examined. All of the mutants were antimorphic for flight ability. E316K and G368E formed muscle with only relatively small defects in structure whilst the others produced IFMs with large amounts of disruption. E334K formed filaments but lacked Z discs. V339I formed no muscle structure in null flies and did not accumulate actin. E364K and G366D both had relatively stable actin but did not form myofibrils. Using an in vitro polymerisation assay we found no significant effects on the ability of the mutant actins to polymerise. E364K and G366D also caused a strong induction of heat shock protein (hsp) synthesis at normal temperatures and accumulated large amounts of hsp22 which, together with the mutant actin, was resistant to detergent extraction. Both E316K and E334K caused a weak induction of hsp synthesis. We discuss how the stability, structure and function of the different mutant actins affects myofibril assembly and function, and the induction of hsps.
Actins↗
The chronic toxicity of equine cadmium metallothionein in the rat.
The extensive renal tubular necrosis that results in male rats after the intravenous injection of a single, low dose of equine kidney cadmium (Cd), zinc(Zn)-metallothionein (MT) (0.2 mg MT-bound-Cd/kg body wt.) is followed within 72 h by active regeneration. With repeated administration of the same dose at 3- or 4-day intervals, lesion resolves although, at least initially, the kidney content of Cd increases progressively. At any time during treatment, about 40% of the accumulated Cd is bound as the endogenous (Cd, Cu)MT. The rate of increase in the renal Cd content is dependent on the ratio of Cd:Zn in the injected metalloprotein, and is appreciably less when the constant dose of protein-bound Cd is given as a (2.4 Cd:1 Zn)MT, than as a (3.0 Cd:1 Zn)MT. On repeated administration of the latter preparation, however, the concentration of Cd in the kidney does not attain a critical concentration, above which persistent tubular damage occurs, but reaches a maximum of about 150-160 micrograms Cd/g wet wt. (after 16 doses) and then declines. After 19 doses of the (2.4 Cd:1 Zn)MT under the same conditions, the renal Cd concentration is submaximal and is less (92 micrograms Cd/g wet wt.) than that after either 16 or 27 doses of the (3.0 Cd:1 Zn)MT. In animals that are dosed with either of the heterologous MT preparations, the first dose, although not innocuous, seems to protect the kidneys against further damage by subsequent doses. Repeated doses, however, lead to vascular changes, e.g. lymphoid infiltration, periarteriole oedema and dilation of the arcuate veins, and to dilation of the glomerular spaces.
Animals↗
The effect of sodium chromate pretreatment on mercuric chloride-induced nephrotoxicity.
Sodium chromate (20 mg/kg, s.c.), which in male rats inflicted necrotic damage mainly in the P1 region (proximal part of the proximal convoluted tubules), protected against proximal tubular necrosis induced by 0.5 or 3.0 mg Hg2+/kg in the P2 (distal part of the proximal convoluted tubules) and P3 (pars recta part of the proximal tubules) regions. Histochemical staining for mercury indicated that chromate increased mercury deposition in those cells of the P1 region which were unaffected by chromate (had intact brush border) but did not decrease mercury deposition in the most severely affected P3 region. Chromate pretreatment actually increased mercury deposition in the kidneys of animals killed 24 h after the injection of 0.5 mg Hg2+. The protective effect was mutual. Cellular proliferation and fibrosis observed 4-5 days after chromate were prevented by injecting 0.5 mg Hg2+/kg 3 days after chromate treatment.
Animals↗
Comparison of the protection given by selenite, selenomethionine and biological selenium against the renotoxicity of mercury.
The protective effect of selenite, seleno-dl-methionine and biological selenium against the renotoxicity of mercury was tested in rats. As the source of biological selenium, the liver soluble fraction of rats given 60 mumoles/kg selenite 3 days before sacrifice was used. The aim of the experiments was to test whether protective efficiency follows the reported order of ability to form HgSe. Mercury was given subcutaneously in doses of 2.5, 5.0 and 7.5 mumoles/kg HgCl2 and selenium was given in equimolar doses at the same time as Hg2+. Liver soluble fraction, biological selenium or liver soluble fraction supplemented with selenite or seleno-dl-methionine were given orally, while in experiments without liver soluble fraction the two selenium compounds were given subcutaneously. Biological selenium was tested only at the two lower dose levels. Both biological selenium and seleno-dl-methionine decreased the urinary excretion of mercury in the first 48 h, but less so than selenite and only selenite decreased the renal content of mercury at the end of this period. Urinary alkaline phosphatase activity and plasma urea nitrogen at the 2.5 and 5.0 mumoles/kg dose levels decreased in the order of no selenium greater than biological selenium greater than seleno-dl-methionine greater than selenite. As the reported HgSe formation increases in the same order, the experiments support the role of HgSe formation in the protective effect. The degree of necrotic damage in the P2 and P3 regions of the proximal tubular cells increased in the same order as the biochemical indicators at the 5.0 and 7.5 mumoles/kg dose levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Ultrastructural changes in the respiratory tract of rats following methyl isocyanate inhalation.
The static exposure of rats to 0.25 mg/l methyl isocyanate for 1 h resulted in damage to the epithelium of the proximal bronchioles and upper airways. Bronchiolar cells exhibited both nuclear and cytoplasmic damage; many epithelial cells, particularly in the bronchi and trachea, were killed and/or dislodged from the basement membrane. A "raft" of cell debris and fibrin lined most of the airways during the 1st week after exposure but repair to the underlying epithelium was well advanced within 2-3 days. The majority of airways were lined by a normal epithelium within 3 weeks of exposure, but isolated foci of hyperplasia and occluded airways probably accounted for continued respiratory impairment.
Animals↗