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PubMed1993

The role of inorganic metals and metalloporphyrins in the induction of haem oxygenase and heat-shock protein 70 in human hepatoma cells.

The role of inorganic metals and metalloporphyrins in the induction of mRNAs for haem oxygenase and heat-shock protein 70 (hsp70), the two heat-shock proteins, was examined in human HepG2 and Hep3B hepatoma cells. SnCl2, but not Sn-protoporphyrin, was found to be a potent inducer of both haem oxygenase and hsp70 mRNAs. In contrast, CoCl2, ZnCl2 and FeCl2 caused little induction of haem oxygenase and hsp70 mRNAs, whereas the porphyrin complexes of these metals strongly induced haem oxygenase mRNA, without influencing the level of hsp70 mRNA. The induction process was largely transcriptional, as judged by the inhibition of induction by actinomycin D, but not by cycloheximide, and by increased transcription demonstrated by nuclear run-off analysis. Since CoCl2 is a potent inducer of haem oxygenase in vivo in animals, the possibility of the biosynthesis of Co-protoporphyrin was examined in human hepatoma cells by incubating them with CoCl2 and protoporphyrin, or delta-aminolaevulinate (ALA), the precursor of protoporphyrin. Both types of treatment led to a potent induction of haem oxygenase mRNA. Co-protoporphyrin formation was also spectrally demonstrated in cells incubated with the metal and ALA. The results of this study indicate that certain metals, e.g. SnCl2, may directly induce haem oxygenase mRNA, whereas with other elements, incorporation of the metal into the porphyrin macrocycle is necessary for induction. Therefore CoCl2, like haemin, may activate the haem oxygenase gene via a haem-responsive transcription factor, whereas SnCl2 may exert its effect via a metal-responsive transcription factor.

Carcinoma, Hepatocellular↗
PubMed2001

Heme oxygenase isoform-specific expression and distribution in the rat kidney.

BACKGROUND: The heme oxygenase (HO) genes, HO-1 and HO-2, are the limiting steps in heme degradation and in the regulation of renal heme-dependent enzymes. Previously we reported that selective overexpression of renal HO-1 resulted in a decrease of microsomal heme and the cytochrome P450-dependent arachidonic acid metabolite, 20 HETE, a vasoconstrictor. The present study was undertaken to explore the relative expression and contribution of each of the HO isoforms to HO activity in the rat kidney. METHODS AND RESULTS. Renal HO activity increased above control levels after an injection of the inducers of HO activity, heme or SnCl2. Stannous Mesoporphyrin (SnMP), a nonselective inhibitor of HO, when used alone or in combination with heme or SnCl2, decreased HO activity. Heme alone and combined with SnCl2 decreased the levels of heme content by 13 and 35%, respectively. Western blot analysis showed that both SnCl2 and heme readily induced HO-1 protein, whereas HO-2 was constitutively expressed. Immunohistochemistry showed the distribution of the HO-1 isoform primarily in proximal convoluted tubules. Western blot analysis exhibited relatively higher levels of HO-1 in isolated proximal tubules and relatively higher HO-2 levels in the thick ascending limbs of the loop of Henle and preglomerular arterioles. In vivo administration of HO-1 and HO-2 antisense oligodeoxynucleotides further confirmed that HO-2, but not HO-1, contributed to the basal HO activity; however, following induction of HO with heme, antisense to HO-1, but not to HO-2, inhibited the induced levels of HO activity. CONCLUSION: These results suggest that HO-2 is constitutively expressed in the rat kidney mainly within tubular and arteriolar structures, and its activity may modulate physiological function under basal conditions. On the other hand, the basal levels of expression of HO-1 in the rat kidney are relatively low, and its contribution to HO activity and the regulation of hemoproteins such as cytochrome P450 become apparent only under pathophysiological conditions causing HO induction.

Animals↗
PubMed2001

Potentiation by stannous chloride of calcium entry into osteoblastic MC3T3-E1 cells through voltage-dependent L-type calcium channels.

The present study was undertaken to confirm that L-type Ca(2+) channels are involved in Ca(2+) entry into osteoblastic MC3T3-E1 cells and to examine the effect of SnCl2, a Ca(2+)]-channel activator, on the intracellular Ca(2+)concentration ([Ca(2+)]i). High K(+)concentration-dependently raised the [Ca(2+)]i. All of the L-type Ca(2+)channel blockers used here, such as nifedipine, nicardipine, verapamil, and diltiazem, and CdCl2 (a non-selective blocker) inhibited the high K(+)-induced [Ca(2+)]i rise, but v-conotoxin GVIA (an N-type blocker) and NiCl2(a T-type blocker) had no effect. Application of SnCl2 alone did not change the [Ca(2+)]i. However, in the presence of high K(+), SnCl2 enhanced the high K(+)-induced [Ca(2+)]i rise, which was inhibited by Ca(2+)]-free medium or nifedipine. In the case where high K(+)was applied prior to SnCl2, SnCl2 alone raised the [Ca(2+)]i by itself. In conclusion, MC3T3-E1 cells possess the voltage-dependent L-type Ca(2+)] channels and SnCl2 facilitates the Ca(2+) entry through the L-type ones under the condition of the membrane depolarization. There is the possibility that Ca(2+) release from intracellular Ca(2+) stores is involved in the action of SnCl2.

3T3 Cells↗
PubMed2002

Effect of finishing and polishing procedures on the gap width between a denture base resin and two long-term, resilient denture liners.

STATEMENT OF PROBLEM: The junction between a long-term, resilient denture liner and the denture base is difficult to finish and polish due to differences in the hardness of the materials. Gaps tend to form during finishing and polishing procedures. PURPOSE: This study measured the junctional gap between 2 long-term, resilient denture liners and a denture base material after different finishing and polishing procedures were performed. The surface smoothness of the 2 liner materials also was evaluated. MATERIAL AND METHODS: Molloplast-B and an experimental, heat-polymerized methyl siloxane-resin-based denture liner were processed (according to the manufacturer's instructions) against Lucitone 199 acrylic resin. Control specimens (n = 20) were 2 mm thick and flat. Experimental specimens (n = 64) were fabricated with a raised center section: a 3- x 5- x 15-mm half-cylindrical ridge with a junction at the top of the cylinder between the liner material and acrylic resin. The specimens were finished with 1 of 6 types of burs and polished with different combinations of rubber-impregnated acrylic polishers, pumice, and tin oxide. The finished specimens were examined and photographed with a scanning electron microscope, and the largest gap along the liner/denture base junction on each specimen was measured. Three-way analysis of variance without replication (P<.05) and post-hoc t tests were used to analyze the data and compare groups. RESULTS; Averaged across finishing and polishing techniques, a larger gap was recorded for the experimental liner material (22 microm) than for Molloplast-B (14 microm) (P<.00005). Qualitative evaluation suggested that the experimental liner material polished better than Molloplast-B. The smoothest surfaces were obtained when specimens were finished with fine-tooth cross-cut carbide burs and polished with both pumice and tin oxide. A comparison between polished and unpolished specimens, averaged over materials and finishing techniques, revealed that polishing reduced gap size (P=.015). CONCLUSION: Within the limitations of this study, the 2 denture liners tested behaved similarly. The results suggest that the size of the gap at the liner/denture base junction may be affected by finishing and polishing techniques and vary among materials.

Acrylic Resins↗
PubMed2003

Different methods of finishing and polishing enamel.

STATEMENT OF PROBLEM: Highly polished enamel surfaces are recommended for axial tooth surfaces that will serve as guiding planes and be contacted by component parts of a removable partial denture. There is little evidence to support the assumption that this tooth modification will provide accurate adaptation of the framework and prevent build-up of plaque. PURPOSE: The aim of this investigation was to evaluate the surface roughness of the tooth enamel, prepared to serve as guiding planes, with different polishing systems. MATERIAL AND METHODS: Four different methods (designated A, B, C, and D) for finishing and polishing the prepared enamel surfaces of 20 freshly extracted third molar teeth were studied. Each method involved 3, 4, or 5 different steps. The roughness of each specimen was measured at the start of each method before recontouring, after recontouring, and after each step of the 4 finishing and polishing procedures. The 4 experimental finishing methods were applied after recontouring the axial surfaces (buccal, lingual, and proximal) of each tooth. Thus the 20 teeth (60 surfaces) were finished and polished by use of 1 of the experimental methods. Surface roughness was measured with a profilometer (microm); the readings of the unpolished enamel surfaces were recorded as control measurements. Results were statistically analyzed with one-way analysis of variance followed by Tukey's test at the 95% level of confidence. RESULTS: The highest roughness mean values (14.41 microm to 16.44 microm) were found when the diamond bur was used at a high speed for tooth preparation. A significant decrease in roughness values was observed with the diamond bur at a low speed (P<.05). Analysis of the roughness values revealed that all polishing methods produced surface roughness similar to that of the corresponding control teeth. CONCLUSION: Within the limitations of this study, all finishing procedures tested effectively promoted an enamel surface similar to the original unpolished enamel.

Analysis of Variance↗
PubMed2002

Preoperative stress conditioning prevents paralysis after experimental aortic surgery: increased heat shock protein content is associated with ischemic tolerance of the spinal cord.

BACKGROUND: All forms of surgical therapy are stressful and injurious. The problems of paralysis, renal dysfunction, and colonic ischemia associated with aortic occlusion are due to acute ischemia-reperfusion injury at the cellular level. Acute-anterior spinal cord ischemia is the most devastating outcome of these iatrogenic-ischemic events. The majority of surgical procedures are performed electively and therefore provide an opportunity to preoperatively condition the patient to minimize these ischemia-related morbidities. OBJECTIVES: We sought to determine whether acute spinal cord injury associated with aortic occlusion can be prevented by induction of the cellular stress response by means of preoperative administration of whole-body hyperthermia or stannous chloride. METHODS: The study consisted of an experimental rabbit model of infrarenal aortic occlusion for 20 minutes at normothermic body temperature. RESULTS: Control rabbits experienced an 88% (7/8) incidence of paralysis after spinal cord ischemia induced by 20 minutes of aortic occlusion, whereas animals treated preoperatively with either whole-body hyperthermia (0/9) or stannous chloride (0/4) never became paralyzed (P <.001 for control vs treated groups). Ischemic protection of the spinal cord was associated with increased content of stress proteins within tissues of pretreated animals. CONCLUSION: Prior induction of the heat shock response in the whole animal will increase the content of stress proteins within the spinal cord and other tissues and result in the prevention of hind-limb paralysis associated with aortic occlusion. We have designated the preoperative induction of the cellular stress response for the prevention of ischemic tissue injury stress conditioning. We suggest that stress-conditioning protocols represent the opportunity to practice preventative medicine at the molecular level.

Animals↗
PubMed2000

Growth on indium-tin oxide-coated glass enhances 32P-phosphate uptake and protein labelling of adherent cells.

A method to improve the efficiency of labelling of adherent cells with radioactive 32p is described. Cells are grown on a glass surface which is coated with indium-tin oxide, a commercially available, transparent material which permits excellent cell adhesion and growth. The results show that a 2 to 3-fold increase in 32p uptake by the cells can be achieved by growing cells on this material, compared to conventional tissue culture plastic.

Animals↗
PubMedDate not supplied

Determination of mercury by cold vapor atomic absorption spectrophotometer in Tongkat Ali preparations obtained in Malaysia.

The DCA (Drug Control Authority), Malaysia, has implemented the phase 3 registration of traditional medicines on 1 January 1992, with special emphasis on the quality, efficacy, and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicine preparations. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation, containing Tongkat Ali, were analyzed for mercury content using cold vapor atomic absorption spectrophotometer. Results showed that 36% of the above products possessed 0.52 to 5.30 ppm of mercury and, therefore, do not comply with the quality requirement for traditional medicines in Malaysia. Out of these 36 products, 5 products that possessed 1.05 to 4.41 ppm of mercury were in fact have already registered with the DCA, Malaysia. However, the rest of the products that contain 0.52 to 5.30 ppm of mercury still have not registered with the DCA, Malaysia. Although this study showed that only 64% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to mercury, they cannot be assumed safe from mercury contamination because of batch-to-batch inconsistency.

Eurycoma↗
PubMed1994

A novel technique for the study of intercellular, junctional communication: electroporation of adherent cells on a partly conductive slide.

One of the effects of neoplastic transformation by a variety of factors is a decrease in gap junctional, intercellular communication (GJIC). The investigation of junctional permeability is usually conducted through the microinjection of the fluorescent dye, Lucifer yellow, followed by observation of its migration into neighboring cells. This is a time-consuming approach, requiring expensive equipment. To overcome these problems, a novel technique was devised which takes advantage of the ability of short electric pulses to create transient "pores" on the cell membrane through which Lucifer yellow can enter, simultaneously and into large numbers of cells, with minimal disturbance to cellular metabolism. Cells were grown on a glass slide, half of which was coated with electrically conductive, optically transparent, indium-tin oxide. An electric pulse was applied in the presence of Lucifer yellow, causing its penetration into the cells growing on the conductive half of the slide, and the migration of the dye to the nonelectroporated cells growing on the nonconductive area was microscopically observed under fluorescence illumination. Using this technique, we investigated the relationship between expression of the middle tumor antigen of polyoma virus (mT) and GJIC in two representative cell systems with different responses to mT. The results show that low mT expression levels, although unable to transform rat F111 cells fully, are able to interrupt GJIC. Although parts of this mechanism might be mediated through protein kinase C (PKC), mT appears to have additional functions. PKC, however, had the opposite effect upon junctional permeability in a clone of mouse NIH-3T3 fibroblasts; intercellular communication in these cells appears to require PKC activity.

3T3 Cells↗
PubMed1982

Effects of dietary tin on tin and calcium metabolism of adult males.

The effects of dietary tin on tin and calcium metabolism were determined in eight adult males. Subjects were fed mixed diets containing 0.11 mg tin daily (control diet) and 49.67 mg tin daily (test diet) for 20 days each in a cross-over design. The level of tin in the control diet was typical of the level of tin found in diets that contained only fresh and frozen foods; the level of tin in the test diet was typical of the amount of tin in diets that contained several servings of certain canned foods. Subjects apparently absorbed 3 and 50% of their dietary tin intake when fed the test and control diets, respectively. Subjects lost significantly more tin in their urine, but retained significantly more tin when fed the test diet rather than the control diet. The fecal and urinary losses and serum levels of calcium were not affected by the dietary treatments.

Absorption↗
PubMed1990

Tc-99m white cell scintigraphy in suspected acute infection.

The usefulness of In-111 labeled white cells in acute infection is well documented but the role of Tc-99m labeled white cell scintigraphy (WCS) has not been as clearly established. Using stannous fluoride colloid and a simple labelling procedure with 20 ml of autologous whole blood, three cases are presented in which Tc-99m WCS established unexpected diagnoses in patients who had remained undiagnosed despite extensive investigation.

Acute Disease↗
PubMed1992

Changes in lung function and pulmonary capillary permeability after cardiopulmonary bypass.

OBJECTIVE: To assess the possibility that changes in lung function following cardiopulmonary bypass are associated with increased pulmonary capillary permeability. DESIGN: A prospective, descriptive study. SETTING: Adult cardiothoracic ICU in a post-graduate teaching hospital. PATIENTS: Ten sequential patients undergoing cardiac surgery requiring cardiopulmonary bypass. MEASUREMENTS: Arterial blood gas tensions, helium dilution end-expiratory lung volume, and carbon monoxide transfer were measured by a rebreathing technique preoperatively and 2 hrs postoperatively. Lung extravascular protein accumulation index was measured by a double-isotope technique 2 hrs postoperatively and in a group of normal controls. RESULTS: Mean +/- SEM alveolar-arterial PO2 gradient increased from 77 +/- 14 torr (10.3 +/- 1.8 kPa) to 138 +/- 24 torr (18.5 +/- 3.2 kPa) (p less than .01). Functional residual capacity decreased by 20.2 +/- 5.6% (p less than .01). Carbon monoxide transfer decreased by 26.7 +/- 5.3% (p less than .01) for the lung as a whole and by 17.9 +/- 3.2% (p less than .01) per liter of accessible gas volume. Protein accumulation index ranged from 0.03 to 3.2 x 10(-3) (median 0.6) postoperatively (median for normal subjects 0.4; p less than .05), although only one patient had a value indicative of clinically important endothelial injury. CONCLUSIONS: Cardiac surgery involving cardiopulmonary bypass results in a deterioration in lung function characterized by a loss of lung volume, a reduction in carbon monoxide transfer, and an increase in the alveolar-arterial PO2 gradient. These changes do not appear to be mediated by an increase in pulmonary endothelial permeability.

Aged↗
PubMed2002

Tin chloride pretreatment prevents renal injury in rats with ischemic acute renal failure.

OBJECTIVE: To investigate whether tin chloride pretreatment ameliorates renal injury in rats with ischemic acute renal failure (IARF) by virtue of its kidney-specific heme oxygenase-1 induction. DESIGN: Randomized, masked, controlled animal study. SETTING: University-based animal research facility. SUBJECTS: Sprague-Dawley male rats, weighing 200-230 g (n = 359). INTERVENTIONS: Rats were injected with tin chloride subcutaneously, because subcutaneous administration of tin chloride is known to specifically and potently induce renal heme oxygenase activity in the rat. Anesthetized rats were subjected to bilateral flank incisions, and the right kidney was removed. Renal ischemia for 40 mins was performed by left renal microvascular clamping, followed by reflow of the blood. MEASUREMENTS AND MAIN RESULTS: Tin chloride treatment specifically induced heme oxygenase-1 mRNA and protein in the proximal tubular epithelial cells of the kidney without apparent cell injury in the rat. Tin chloride treatment before renal ischemia augmented the induction of heme oxygenase-1 in IARF rats at both transcriptional and protein concentrations in the renal epithelial cells compared with IARF animals. Tin chloride pretreatment, which decreased microsomal heme concentration, ameliorated the ischemic renal injury as judged by the significant decrease in serum creatinine and blood urea nitrogen concentrations and the lesser tubular epithelial cell injuries. In contrast, inhibition of heme oxygenase activity by treatment with tin mesoporphyrin, which increased microsomal heme concentration, abolished the beneficial effect of tin chloride pretreatment. CONCLUSION: These findings indicate that tin chloride pretreatment significantly ameliorates renal injury in rats with IARF by virtue of its specific heme oxygenase-1 induction in renal epithelial cells. These findings also suggest that heme oxygenase-1 induction plays an important role in protecting renal cells from oxidative damage caused by heme.

Acute Kidney Injury↗
PubMed1989

Manipulation of cytochrome P-450 dependent renal thromboxane synthase activity in spontaneously hypertensive rats.

Thromboxane synthase is a cytochrome P-450-like enzyme requiring an iron-centered oxygen attack of the prostaglandin endoperoxide substrate (PGH2) for subsequent thromboxane A2 (TxA2) formation. The activity and levels of P-450 enzymes can be manipulated by decreasing heme availability. Stannous chloride (SnCl2) selectively induces renal heme oxygenase activity, depleting heme and decreasing hemoprotein synthesis. We therefore manipulated the renal cytochrome P-450 system to influence thromboxane synthase activity, as measured by the conversion of 14C-PGH2 to thromboxane B2 (TxB2) in renal cortical microsomes from spontaneously hypertensive rats (SHR). Seven-week-old SHR were treated subcutaneously with SnCl2 (1, 10 and 15 mg/100 g body weight) for 4 consecutive days, and cortical microsomal heme oxygenase activity, heme content, P-450 content, thromboxane synthase activity and systolic blood pressure were measured. Heme oxygenase activity was significantly increased from 1058 +/- 62 nmol/mg protein in controls to 3125 +/- 918, 5057 +/- 690--and 4236 +/- 581 nmol/mg protein in SHR treated with 1, 10 and 15 mg/100 g body weight SnCl2, respectively. The increase in heme oxygenase activity was associated with corresponding decreases in heme content (0.29 mumol/mg protein, for control to 0.12 mumol/mg protein for SHR treated with SnCl2, 10 mg/100 g body weight) and cytochrome P-450 content (0.18 +/- 0.1 nmol/mg protein for control to 0.06 +/- 0.01 nmol/mg protein for SHR treated with SnCl2 10 mg/100 g body weight). The reduction in heme and P-450 content was associated with a reduction in thromboxane synthase activity, i.e., decreases of 38, 35 and 47% from control levels at doses of 1, 10 and 15 mg/100 g body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗