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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of chloride in fluid transport of the rabbit corneal endothelium was examined by measuring changes in corneal thickness following ion substitutions or addition of ion transport inhibitors in media superfusing the isolated tissue. Normal fluid transport is indicated by maintenance of constant thickness in a fresh cornea or thinning (deturgescence) of a preswollen deepithelialized cornea to its initial thickness at approximately 40 microns/h. These patterns are seen when tissues are superfused with HCO(3-)-Ringer containing 114 mM Cl-. When Cl- was substituted with gluconate, glucuronate, or SO4(2-) fresh and preswollen corneas immediately thinned at greater than 150 microns/h to a value less than 300 microns and then began to swell at 30 microns/h to above their original thickness. Substitution of Cl- with NO3- or Br- had a negligible immediate thinning effect, but fresh corneas subsequently swelled and preswollen corneas failed to deturgesce fully. The rapid thinning (called a "downtransient") observed with gluconate, glucuronate, and SO4(2-) also occurred in these media when ion and fluid transport were completely inhibited with ouabain or stilbenes or by absence of HCO3-, indicating that the thinning results from osmotic gradients induced by ionic reflection coefficients different from that of Cl-. When the downstransient was avoided in deepithelialized corneas by preswelling with the same Cl(-)-free media on both sides of the cornea, corneas maintained a constant but swollen thickness in gluconate and in NO3- or Br- deturgesced slowly and incompletely; ouabain or stilbenes caused further swelling in all media. We conclude that absence of Cl- partially impairs fluid transport, most probably via its role in a Cl(-)-HCO3- exchanger which has been proposed in a recent model of endothelial fluid transport.
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PMID:Chloride is required for fluid transport by the rabbit corneal endothelium. 159 Mar 58

Eggshell formation and egg production in domestic fowl were studied following the administration of methyl mercury (two dose regimes: 5 mg daily for 6 consecutive days and 1 mg daily for 50 consecutive days). A daily oral dose of 5 mg of methyl mercury for 6 consecutive days induced significant eggshell thinning and deformation and inhibited egg production. Uptake of 45Ca and synthesis of prostaglandins by a homogenate of eggshell gland mucosa from methyl-mercury-treated birds were significantly reduced, as was the calcium content of blood plasma. A daily oral dose of 1 mg of methyl mercury administered for 50 consecutive days also induced eggshell deformation and thinning and reduced egg production. This dose did not, however, have significant effects on the following: 45Ca uptake and prostaglandin synthesis by a homogenate of the eggshell gland mucosa; 45Ca uptake by a homogenate of duodenal mucosa; the Ca content of the blood plasma, shell gland mucosa or shell gland lumen; the HCO3- content of the shell gland lumen or the specific gravity of tibia. Methyl mercury added in vitro to a homogenate of eggshell gland mucosa significantly stimulated the synthesis of prostaglandins PGF2 alpha and PGE2. Addition of mercury chloride to the same type of preparation stimulated the synthesis of PGF2 alpha at the expense of thromboxane (TxB2) synthesis. Administration of 5 mg methyl mercury for 6 consecutive days seemed to reduce the availability of calcium for eggshell formation. This effect could have been due to a direct inhibitory effect of methyl mercury on calcium uptake from the gastrointestinal tract and/or to mobilization of medullary bone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of methyl mercury at different dose regimes on eggshell formation and some biochemical characteristics of the eggshell gland mucosa of the domestic fowl. 774 99

Eggshell thinning in ducks was induced by administration of p,p'-DDE in the diet (40 mg/kg food) for 45 days. This treatment resulted in a 19% reduction of the Eggshell Index (EI). Shells from calcifying eggs obtained at the time of slaughter showed a 36% reduction of EI. Prostaglandin synthesis by a homogenate of eggshell gland mucosa from p,p'-DDE-treated ducks was reduced by 24%. HCO3(-)-stimulated ATPase activity by a homogenate of eggshell gland mucosa from p,p'-DDE-treated ducks was not significantly changed. The calcium content of eggshell gland mucosa was increased to 127% in p,p'-DDE-treated ducks. p,p'-DDE-treated ducks showed profound changes in the shell gland luminal content of several ions. Calcium (-43%), sodium (-15%), potassium (-15%), bicarbonate (-33%) and chloride (-29%) were all significantly reduced in p,p'-DDE-treated ducks. The content of phosphate was unchanged. These findings are discussed in relation to a proposed mechanism for p,p'-DDE-induced eggshell thinning that involves inhibition of prostaglandin synthesis in eggshell gland mucosa.
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PMID:Changes in the levels of different ions in the eggshell gland lumen following p,p'-DDE-induced eggshell thinning in ducks. 788 10

Type X collagen has been implicated in the morphogenetic events of endochondral ossification (EO), including the calcification of hypertrophic cartilage and trabeculae prior to their replacement by bone and marrow. Recently, transgenic mice, which expressed a truncated collagen X protein, were reported to exhibit morphologic alterations in all tissues arising through EO. Specifically, the growth plates were compressed within the zone of cartilage hypertrophy, and the number and size of calcified trabeculae were reduced. The condition in the mouse is comparable to Schmid metaphyseal chondrodysplasia in humans for which, to date, 20 defined type X collagen mutations have been reported. The transgenic mouse showed no alterations in mineralization by conventional histology, however, it did show a decrease in newly formed bony trabeculae, and a thinning of periosteal bones. Fourier transform infrared (FTIR) spectroscopy has previously been shown to provide quantitative and qualitative information about the relative amount of mineral and carbonate present, mineral composition, and crystal perfection. To determine whether the expression of abnormal collagen X molecules had an effect on mineral properties, the "quality" of mineral crystals was analyzed in thin sections of tibia from day 17 and day 25 genotypically negative (normal) and positive (mutant) mice from several independent transgenic mouse lines showing varying degrees of the mutant phenotype, by means of Fourier transform infrared microscopic analysis (FTIRM). The results indicate definite differences between normal and transgenic mice calcified cartilage mineral, both in the amount present and the "quality" of the crystals. Calcified cartilage mineral from transgenic mice exhibited less crystallinity and higher acidic phosphate content than the corresponding mineral from normal specimens.
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PMID:Fourier transform infrared microspectroscopic analysis identifies alterations in mineral properties in bones from mice transgenic for type X collagen. 885 59

Corneal stromal hydration is maintained by an active HCO3- transport mechanism located in the corneal endothelium. Whilst modulation of transport activity by changes in intracellular cAMP concentration have been noted, the site of effect is undefined. To resolve this question, the effects of Rolipram, a cAMP phosphodiesterase inhibitor, on endothelial physiology were determined. Addition of 0.1 mM Rolipram caused a threefold increase in intracellular cAMP with no change in cGMP. Associated with the increase in cAMP was a transient whole corneal thinning and a similarly transient increase in trans-endothelial potential difference, short-circuit current and resistance. The membrane potential hyperpolarized and the intracellular Na+ concentration decreased. The decreased intracellular Na+ was associated with an increased rate of Na+ extrusion between the endothelial cell and extracellular space. It is concluded that Rolipram increases the concentration of cAMP which activates the basolateral membrane Na+/K+-ATPase activity and increases net HCO3- transport. In addition there is a reduction in endothelial permeability which combined with the increase in pump activity may jointly explain the observed stromal thinning. The duplicity of responses indicates that if cAMP has a physiological role in regulating corneal hydration then it may operate on both the endothelial pump and the endothelial permeability.
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PMID:Modulation of corneal endothelial hydration control mechanisms by Rolipram. 1104 52

This study represents the first report of the physical and chemical changes occurring in coatings of failed hydroxyapatite (HA)-coated titanium implants obtained from a comprehensive, multicenter human dental implant study. A total of 53 retrieved samples were obtained and compared with unimplanted controls with the same manufacturer and similar manufacture dates. Forty-five retrieved implants were examined for surface characteristics and bulk composition. Implants were staged based on implantation history: stage 1 (implants retrieved between surgical placement and surgical uncovering), stage 2 (implants retrieved at surgical uncovering and evaluation), stage 3 (implants retrieved between surgical uncovering evaluation and occlusal loading), and stage 4 (implants retrieved after occlusal loading). Scanning electron microscopy showed progressive coating thinning with implantation time. At later stages, bare Ti metal was detected by energy-dispersive X-ray analysis and electron spectroscopy for chemical analysis. Increases in Ti and Al (2-7.5 atm % each) were detected at the apical ends of all stage 4 samples. In unimplanted coatings, X-ray diffraction analysis demonstrated the presence of amorphous calcium phosphate, beta-tricalcium phosphate, tetracalcium phosphate, and calcium oxide in addition to large hydroxyapatite crystals (c axis size, D002 = 429 +/- 13 A; a axis size, D300 = 402 +/- 11 A, a/c aspect ratio 0.92). The nonapatitic phases disappeared with increased implantation time, although there was a persistence of amorphous calcium phosphate. Bulk coating chemical analysis showed that Ca/P ratios for implant controls (1.81 +/- 0.01) were greater than stoichiometric HA (1.67) and decreased for implant stages 3 and 4 (1.69 +/- 0.09 and 1.67 +/- 0.09, respectively), explained by the dissolution of the non apatitic phases. Crystal sizes also changed with implantation times, being smaller than the control at all but stage 4. Fourier transform infrared analyses agreed with these results, and also indicated the accumulation of bone (protein and carbonate-apatite) in the retrieved coatings. The accumulation of bone was not stage dependent. These findings indicate that there was some biointegration with the surrounding bone, but the greatest changes occurred with the HA coating materials, their loss, and chemical change.
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PMID:Physicochemical study of plasma-sprayed hydroxyapatite-coated implants in humans. 1142 92

The corneal endothelium transports solute from the stroma to the aqueous humor, maintaining corneal hydration. Currently, little is known about how this active transport system is controlled. The purpose of this study is to investigate in greater detail the corneal response to small NaCl osmotic perturbations using a more refined automatic thickness measurement system in a search for response signatures of transport control. Adult New Zealand White rabbit corneas were debrided of their epithelium, excised and mounted in perfusion chambers. The endothelium, thus isolated, was bathed in isotonic Glutathione Bicarbonate Ringer's (GBR) solution and the bare anterior stroma was covered with silicone oil. Following stabilization in isotonic GBR, the endothelial perfusate was altered by +/-15 mOsm or+/-45 mOsm for 1 hr and 45 min by addition or removal of NaCl and returned (reversal) to GBR for 1 hr and 45 min. An enhanced, automatic scanning specular microscope monitored stromal thickness. The effective membrane transport coefficients were determined from the stromal thickness vs. time curves using an established numerical model of corneal hydration dynamics. It was found that the small (+/-15 mOsm) NaCl perturbations of the rabbit corneal endothelium resulted in a rapid trans-endothelial stromal volume control response that was not reversible after return to GBR. Long after the expected dissipation of the induced transients, this thickness 'controlling' response ultimately resulted in a sustained net thinning of 14 microm following the hypotonic perturbation and reversal, and a net swelling of 16 microm following the hypertonic perturbation and reversal. Model calculations indicated that the change induced by the perturbation could be explained by an immediate and persistent reduction of the passive endothelial NaCl permeability by 26% for the -15 mOsm perturbation compared to the +15 mOsm perturbation. This change persisted even after return to GBR. In contrast, the larger (+/-45 mOsm) perturbations did not elicit a similar response consistently. Our data suggest that trans-endothelial fluid transport can be rapidly modulated to control stromal hydration in response to small NaCl osmotic stresses in a way that cushions the shock and reduces the change in corneal thickness. Moreover, this behavior is not reversible in the short term, and may assist the regulation of corneal hydration homeostatically.
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PMID:NaCl osmotic perturbation can modulate hydration control in rabbit cornea. 1257 64

The shear-rate dependence of viscosity is studied for model polymer melts containing various concentrations of spherical filler particles by molecular-dynamics simulations, and the results are compared with the experimental results for calcium-carbonate-filled polypropylene. Although there are some significant differences in scale between the simulated model polymer composite and the system used in the experiments, some important qualitative similarities in shear behavior are observed. The trends in the steady-state shear viscosities of the simulated polymer-filler system agree with those seen in the experimental results; shear viscosities, zero-shear viscosities, and the rate of shear thinning are all seen to increase with filler content in both the experimental and simulated systems. We observe a significant difference between the filler volume fraction dependence of the zero-shear viscosity of the simulated system and that of the experimental system that can be attributed to a large difference in the ratio of the filler particle radius to the radius of gyration of the polymer molecules. In the simulated system, the filler particles are so small that they only have a weak effect on the viscosity of the composite at low filler volume fraction, but in the experimental system, the viscosity of the composite increases rapidly with increasing filler volume fraction. Our results indicate that there exists a value of the ratio of the filler particle radius to the polymer radius of gyration such that the zero-shear-rate viscosity of the composite becomes approximately independent of the filler particle volume fraction.
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PMID:Molecular-dynamics simulation of model polymer nanocomposite rheology and comparison with experiment. 1632 Nov 11

Milk of calcium is a viscous colloidal suspension of calcium carbonate, calcium phosphate, or calcium oxalate, or a mixture of these compounds. The calcific material gravitates to the dependent portion of a cystic cavity. Crescent- or hemisphere-shaped calcium density with a sharp horizontal upper border at the milk of calcium-clear fluid interface confirms the diagnosis. Bilateral milk of calcium in the renal pelvis or in dilated calyces is very rare and has not been reported in patients with spinal cord injury. A 63-year-old male patient with T-10 paraplegia presented with recurrent urinary tract infections. X-ray of the kidneys, taken with the vertical beam while the patient lay supine, revealed a poorly defined opacity overlying the lower pole of the right kidney. Findings on ultrasonography of the kidneys were interpreted as a large, staghorn-type calculus in the dilated lower pole calyx of the right kidney. Because x-ray of the kidneys showed a poorly defined opacity overlying the lower pole of the right kidney, milk of calcium was suspected, and computed tomography (CT) of the kidneys was performed. Calcific debris with horizontal layering in the lower pole calyces of both kidneys was seen; this confirmed the diagnosis of milk of calcium. A 62-year-old female patient with C-7 tetraplegia underwent ileal conduit urinary diversion. Subsequently, she developed calculi in the right kidney, which were treated with shock wave lithotripsy. Follow-up x-ray revealed faintly opaque shadows with indistinct margins in the region of both kidneys. Intravenous urography showed cortical thinning at the upper poles and blunting of the calyces, suggestive of chronic pyelonephritis. The right renal pelvis was bulky, and bilateral renal calculi were diagnosed during ultrasonography; however, the presence of faintly radio-opaque shadows with indistinct margins raised suspicions of renal milk of calcium. A CT scan of the kidneys, which was performed in the supine and subsequently in the prone position, revealed gravity-dependent layering of calcific material in the pelves of both kidneys and in the midpole calyces of the right kidney, thus confirming the diagnosis of milk of calcium. In conclusion, CT scan of the kidneys confirmed the diagnosis of bilateral renal milk of calcium, a very rare entity in patients with spinal cord injury. Awareness of typical and unique features of milk of calcium during imaging enables physicians to recognize renal milk of calcium and to differentiate it from nephrolithiasis, thereby avoiding unwarranted interventions such as shock wave lithotripsy or endoscopic procedures.
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PMID:Bilateral renal milk of calcium masquerading as nephrolithiasis in patients with spinal cord injury. 1766 Jan 62

The combined effects of the processing parameters upon rheological properties of biopolymers produced by Rhizobium tropici were studied as a function of the Ca(+2) ions' concentration variation, yeast extract concentration added to the medium, aeration, and agitation, maintaining the mannitol concentration in 10 g/L. The experiments were carried out using a fermenter with 20-L capacity as a reactor. All processing parameters were monitored online. The temperature [(30 +/- 1) degrees C] and pH values (7.0) were kept constant throughout the experimental time. As a statistical tool, a complete 2(3) factorial design with central point and response surface was used to investigate the interactions between relevant variables of the fermentation process: calcium carbonate concentration, yeast extract concentration, aeration, and agitation. The processing parameter setup for reaching the maximum response for rheological propriety production was obtained when applying mannitol concentration of 10.0 g/L, calcium carbonate concentration 1.0 g/L, yeast extract concentration 1.0 g/L, aeration 1.30 vvm, and agitation 800 rpm. The viscosimetric investigation of polysaccharide solutions exposed their shear-thinning behavior and polyelectrolytic feature.
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PMID:Processing parameters matching effects upon Rhizobium tropici biopolymers' rheological properties. 1843 96


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