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PubMed1995

Increased dietary NaCl intake influences lens transport properties in Sprague-Dawley rats.

Several years ago, we reported a high frequency of cataracts in Dahl salt-sensitive rats (DS) which led us to carry out a series of studies, such as longitudinal ouabain-sensitive lens 86Rb uptake measurements. Yet, throughout all of our work, we used the Dahl salt-resistant rat (DR) as our control group, despite the fact that DR is a strain resistant to even experimental hypertension such as that resulting from renal cellophane wrapping. Thus, in the present study we assessed lens short-circuit current (Isc) in adult Sprague-Dawley rats (SD) from which DS and DR were derived. Sprague-Dawley rats were studied during chronic normal vs high NaCl intake. These studies showed that basal Isc and calculated translenticular potential difference (PDt) were nearly doubled by this dietary regimen. Sequential addition of BaCl2 and ouabain to the isolated lens anterior surface bath also revealed increased BaCl2-sensitive as well as BaCl2- and ouabain-insensitive lens Isc in SD kept on a high NaCl diet. There was a statistically insignificant tendency for lens ouabain-sensitive Isc to increase in SD given a high NaCl diet. These findings were unrelated to levels of arterial blood pressure which were not altered by chronic high NaCl intake in adult SD. Our data suggest the possibility of increased lens barium and ouabain insensitive ionic permeabilities combined with possibly increased lens fiber potassium concentration, as a response to chronic high dietary NaCl in the normal rat. The nature of the barium and ouabain insensitive component of the lens Isc that rises during chronic high NaCl intake requires elucidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

An improved technique for sequential R-, Q- and C-banding of bone marrow chromosomes.

A procedure for the sequential staining of metaphase cells to provide R-banding, Q-banding and C-banding of chromosomes is described. The combined techniques allow more precise identification of marker chromosomes and more accurate definition of breakpoints in the consistent chromosome translocations that are associated with certain human malignancies.

Barium↗
PubMed1994

Diacetyl for blocking the histochemical reaction for arginine.

Two different histochemical methods for blocking the guanidinium group of arginine in formalin fixed, paraffin embedded material are reported here. One procedure uses diacetyl with short incubation times and high pH, the other uses the trimer of the diacetyl reagent and requires longer incubation times but moderate pH. The diacetyl reagent is recommended despite its high pH because the preparation of the diacetyl trimer is laborious and time-consuming.

Arginine↗
PubMed1990

Alteration in the sarcolemmal Na(+)-K+ pump of hindquarters resistance arteries in DOCA-salt rats.

It has been suggested that a circulating inhibitor of the Na(+)-K+ pump contributes to the development and maintenance of DOCA-salt hypertension. However, the discordant results have been reported as to whether the sarcolemmal Na(+)-K+ pump in DOCA-salt hypertension is inhibited. Furthermore, no study has examined alteration in the sarcolemmal Na(+)-K+ pump of the true resistance arteries. We examined hindquarters vasoconstriction induced by ouabain (10(-3) M) in the vascularly isolated hindquarters of the DOCA-salt treated or control rats, which were perfused with Krebs-Henseleit solution. Hindquarters vasoconstriction induced by ouabain (10(-3) M) was greater in the prehypertensive and hypertensive DOCA-salt rats than in the corresponding control rats (p less than 0.01). We also examined hindquarters vasoconstriction induced by ouabain (10(-3) M) in the vascularly isolated hindquarters of the normal assay rats which were perfused by the plasma obtained from the DOCA-salt or control rats. The plasma of the prehypertensive and hypertensive DOCA-salt rats attenuated ouabain-induced hindquarters vasoconstriction in the assay rats (p less than 0.01). The plasma of the DOCA-salt rats did not alter nonspecific vasoconstriction caused by barium chloride. These results suggest that the plasma of the prehypertensive and hypertensive DOCA-salt rats had an inhibitor of the sarcolemmal Na(+)-K+ pump of the resistance arteries, but the sarcolemmal Na(+)-K+ pump molecules of the resistance arteries of those rats were increased. The in vivo activity of the sarcolemmal pump of the resistance arteries of the DOCA-salt rats would be determined by the relative influence of increased pump molecules and a circulating pump inhibitor.

Animals↗
PubMed1980

The mechanical stability of barium titanate (ceramic) implants in vitro.

Dense, polycrystalline barium titanate (BaTiO3) specimens showed a modulus of rupture of 85.5 +/- 9.0 MPa and a compressive strength of 486 +/- 75 MPa. These values are considerable higher than those which had been previously reported. In addition, there was no significant drop in compressive strength after in vitro aging for 4 weeks in saline solution.

Barium↗
PubMed1998

Antagonist of nitric oxide synthesis inhibits nerve-mediated relaxation of isolated strips of rumen and reticulum.

The present study investigated the possibility that nitric oxide is a nonadrenergic, noncholinergic neurotransmitter of nerves that are intrinsic to the forestomach. Tunica muscularis, myenteric plexus preparations of bovine reticulum and rumen were maintained in vitro in a physiological solution of buffer that contained scopolamine. Trains of electric field stimulation transiently reduced (relaxed) the tone induced by BaCl2. NG-Nitro-L-arginine methyl ester, a nitric oxide synthase competitive antagonist, inhibited relaxation of the rumen and reticulum preparations that had been induced by the electrical field. The actions of NG-nitro-L-arginine methyl ester were partially reversed by L-arginine. These data suggest that nitric oxide, or a related substance, is an inhibitory neurotransmitter of nerves that are intrinsic to tunica muscularis, myenteric plexus preparations of the bovine forestomach.

Animals↗
PubMed1993

The application of fluorinated aromatic dimethacrylates to experimental light-cured radiopaque composite resin, containing barium-borosilicate glass filler--a progress in nonwaterdegradable properties.

This study investigated the durability, especially the nonwaterdegradable qualities, of experimental light-cured composite resin containing barium-borosilicate glass filler. For this purpose, Bis-GMA, a typical component of base monomer in conventional composite resin, was replaced by Bis-GMA-F which is water-repellent. After over 20,000 thermal cycles, the composite resin containing Bis-GMA retained only 60 approximately 70% of its initial compressive, diametral tensile, flexural strength and flexural elastic modulus. However, the experimental composite resin containing Bis-GMA-F as a resin matrix showed no loss of compressive, diametral tensile strength or flexural elastic modulus, although flexural strength showed some deterioration. It was considered that the difference between Bis-GMA-F and Bis-GMA, as resin matrix, caused variation in the characteristics of water sorption.

Barium Compounds↗
PubMed1995

Relationship between particle size of barium glass filler and water sorption of light-cured composite resin.

The reaction of barium glass filler with water was determined by investigation of the effects of the particle size of barium glass filler on the water sorption rate and the mechanical properties of composite resin. Barium glass and quartz were milled to obtain powders with different average particle sizes. These powders were silanized and used as inorganic filler in composite resin. Photoactivated base monomer was loaded at 65% (w/w) with these fillers to prepare the composite resin paste. The water sorption of barium glass filled resin was always more than that of quartz filled resin. The amount of sorbed water obtained by barium glass filled resin increased as the particle size decreased. The particle size of the quartz filler did not affect the water sorption. The flexural strength of barium filled resin decreased after water immersion more than that of the quartz filled resin as the particle size decreased. These results suggest that the water durability of barium glass is low and the surface of barium glass filler is damaged by water. Water would be retained in the interface between the barium glass filler and the matrix resin.

Absorption↗
PubMed2002

Relaxation modulus of denture base resin reinforced with woven glass fibers.

This study examined the reinforcing effect of woven glass fibers on the relaxation modulus by three-point loading of denture base resin. Three sandwich-type flexure test specimens polymerized by heating were used, all 3 mm thick: glass fibers in compression (U type); glass fibers in the center (C type); and glass fibers in tension (L type). Unreinforced specimens (ACR) were produced as a control. The relaxation modulus after 8 sec from the start of stress (Er(8)) was calculated from stress relaxation curves. In the glassy state, the Er(8)s of the U and L types were greater than those of the ACR and C types. In the rubbery state (plateau region), the Er(8)s of the U and L types were greater than those of the ACR and C types. The woven glass fibers added to the U and L type specimens increased the relaxation modulus of PMMA near the oral temperature; moreover, they inhibited stress relaxation when the temperature increased.

Algorithms↗
PubMed1998

Analysis of multidrug effects by parameter method.

AIM: To set up a new analytic method for multidrug effects. METHODS: Based on the principles of the target site kinetics and the equieffective test, a new mathematical model was set as Q = (Eo-Ee)/magnitude of Ee x W-sx x T (-1 < Q < 1 addition, Q < or = -1 antagonism, Q > or = 1 synergism) where Eo = a fitted value of the observed effect of a combination, Ee = an expected value of combined effect, W = an equieffective criterion decided by a special field, sx = a common standard error of Eo and Ee, and T = a value of one-sided t0.05. All the calculations were completed with computer. Dose-effect data from different types of experiments were fitted by the new model and the results were compared with those of other methods. RESULTS: This parameter method dealt with different types of data well fitted with the Hill equation, and was not limited to analyze receptor interaction of drugs, or the number of combined drugs. A series of Q values was obtained from all levels of dose-effect for a systematic analysis. The analysis took the criterion of a special field and laboratory error into account. CONCLUSION: This parameter method can effectively analyze the multidrug effects.

Acetylcholine↗
PubMed1999

The electrical properties of auditory hair cells in the frog amphibian papilla.

The amphibian papilla (AP) is the principal auditory organ of the frog. Anatomical and neurophysiological evidence suggests that this hearing organ utilizes both mechanical and electrical (hair cell-based) frequency tuning mechanisms, yet relatively little is known about the electrophysiology of AP hair cells. Using the whole-cell patch-clamp technique, we have investigated the electrical properties and ionic currents of isolated hair cells along the rostrocaudal axis of the AP. Electrical resonances were observed in the voltage response of hair cells harvested from the rostral and medial, but not caudal, regions of the AP. Two ionic currents, ICa and IK(Ca), were observed in every hair cell; however, their amplitudes varied substantially along the epithelium. Only rostral hair cells exhibited an inactivating potassium current (IA), whereas an inwardly rectifying potassium current (IK1) was identified only in caudal AP hair cells. Electrically tuned hair cells exhibited resonant frequencies from 50 to 375 Hz, which correlated well with hair cell position and the tonotopic organization of the papilla. Variations in the kinetics of the outward current contribute substantially to the determination of resonant frequency. ICa and IK(Ca) amplitudes increased with resonant frequency, reducing the membrane time constant with increasing resonant frequency. We conclude that a tonotopically organized hair cell substrate exists to support electrical tuning in the rostromedial region of the frog amphibian papilla and that the cellular mechanisms for frequency determination are very similar to those reported for another electrically tuned auditory organ, the turtle basilar papilla.

4-Aminopyridine↗
PubMed1998

Adhesive bonding of fractured anterior teeth: effect of wet technique and rewetting agent.

PURPOSE: To compare the fracture strength of intact teeth with that of fractured crowns bonded with adhesive and a resin material on either wet or dry dentin, or dried dentin rewetted with a rewetting agent for various periods of time. MATERIALS AND METHODS: Sheep central incisors were divided into seven groups, each of 10 teeth. Group 1: Intact teeth tested for fracture strength in an Instron testing machine and used as controls. Groups 2-7 were sectioned in a vice equipped with sharp blades, 2.5 mm away from and parallel to the incisal edge. The two fracture surfaces were etched with 37% phosphoric acid for 15 s and rinsed with water for 5-6 s. Group 2: The surfaces were air-dried for 2 s. Group 3: As for Group 2 but the surfaces were rewetted with Aqua-Prep for 2 s and immediately air-blasted to remove excess. Group 4: As for Group 3, but the rewetting agent was applied for 10 s before air-blasting. Group 5: As for Group 4, but the rewetting agent was applied for 20 s. Group 6: As for Group 4, but the rewetting agent was applied for 30 s. Group 7: As for Group 2, but the surfaces were left moist after etching and rinsing by gently shaking the specimens twice. The fracture surfaces of Groups 2-7 were rebonded with All-Bond 2 adhesive system and Aeliteflo composite. After 48 hrs the restored teeth were debonded in the Instron testing machine. Fracture strengths were calculated and compared with the fracture strength of intact teeth (control group). RESULTS: Newman-Keuls' multiple range test revealed that there was a statistically significant difference between the control mean and the means of Groups 2 and 3. All other means were not significantly different. Drying of the dentin surface decreased the bonding strength, and rewetting of the dried dentin for 2 s was not sufficient to rewet the collapsed collagen fibers, as indicated by a decrease of fracture strength.

Acid Etching, Dental↗
PubMed1999

Esthetic and functional reproduction of occlusal morphology with composite resins.

The increasing use of composite resin restorations in posterior sectors produces some difficulties in the exact reproduction of occlusal morphology. In this article we present a new operative method that allows a quick and precise reproduction of occlusal morphology with minimal carious destruction of the occlusal enamel of posterior dental elements in the case of initial carious lesions. This method is indicated for class I and II carious lesions and is based on a preoperative record of the occlusal morphology made with a transparent silicone mold. This mold is placed on the tooth after the application of the last layer of composite resin, which is then polymerized through the silicone. Illustrated as a clinical case, the method is particularly rapid, easy to perform, and contributes to the improved quality and subsequent success of composite restorations in posterior sectors.

Adult↗
PubMed1999

Anti-arrhythmic effects of sophoridine and oxysophoridine.

AIM: To compare the effects of oxysophoridine (Oxy) and sophoridine (Sop) on experimental arrhythmias and myocardial physiologic properties. METHODS: Arrhythmias were induced by drugs and myocardial ischemia. Physiologic properties were determined on isolated heart atria. RESULTS: Oxy 500 mg.kg-1 (1/6 LD50) decreased the incidence of ventricular arrhythmias induced by aconitine (P < 0.01), increased the threshold dose of ouabain-induced ventricular premature (VP, P < 0.05), ventricular tachycardia (VT, P < 0.05), ventricular fibrillation (VF, P < 0.01), and cardiac arrest, (P < 0.01). After i.v. Oxy 500 mg.kg-1 into the rats with ligation of left anterior descending coronary artery, the total numbers of ectopic beats were decreased (P < 0.05), the incidence of VF was lowered, and the duration of VT was shortened (P < 0.01). Oxy 250 mg.kg-1 (1/13 LD50) i.v. shortened the duration of arrhythmias induced by BaCl2 (P < 0.01) and delayed the onset of arrhythmias induced by chloroform-epinephrine (P < 0.05). Oxy produced dose-dependent positive inotropic effects in the isolated left atrial of guinea pigs, increased the concentration of epinephrine to elicit automaticity in left atria, decreased slightly the excitability, and prolonged the functional refractory period. Sop produced the similar effects on arrhythmias as Oxy. CONCLUSION: Oxy produced the similar anti-arrhythmic effects as Sop did at the equivalent effective dose.

Aconitine↗
PubMed2000

Dental photostimulable phosphor radiography.

Photostimulable phosphor radiography (PPR), a mature industry in medical imaging, became available in dentistry in 1994. At least three dental PPR systems have been made available commercially since that time. Although dental PPR offers a number of advantages over film-based methods, some aspects of dental PPR need improvement. Further research is needed to more fully compare and contrast this modality with film-based methods.

Analog-Digital Conversion↗
PubMed1999

1-year clinical evaluation of one-step in non-carious cervical lesions.

PURPOSE: To evaluate the 1-year clinical retention rate of restorations of non-carious cervical lesions placed using a "one-bottle" adhesive (One-Step) and one of two low modulus resin-based composite (RBC) restorative materials (AEliteflo or Bisco Glaze) or a microfilled RBC (Silux Plus). MATERIALS AND METHODS: 105 non-carious cervical lesions in 14 patients, mean age 60 years, were restored using either AEliteflo, Bisco Glaze or Silux Plus with One-Step dentin bonding agent. The dentin surface was lightly roughened with a fine diamond stone, cleaned with pumice and water and restored according to the manufacturers' instructions. Patients were recalled at 6 months and 1 year, and the restoration sites examined. RESULTS: At 6 months all restorations were present. At 1 year, five restorations were missing (two Silux, three AEliteflo), three of which were in one patient. A cumulative retention rate of 95% was recorded. A small number of restorations exhibited marginal discoloration, but this was believed to be due to excess RBC on unetched enamel.

Adult↗