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PubMed1975

Use of N-benzoyl-L-tyrosine thiobenzyl ester as a protease substrate. Hydrolysis by alpha-chymotrypsin and subtilisin BPN.

In the course of searching for specific chromogenic substrates which might be useful in screening for protease-deficient mutants of Bacillus subtilis, we have developed a method for the synthesis of N-benzoyl-L-tyrosine thiobenzyl ester (BzTyrSBzl) in good yield. Spontaneous base hydrolysis of this thiol ester is low, but several serine proteases hydrolyze it readily. Spectrophotometric measurement of the hydrolysis of the ester in the presence of 5,5'-dithiobis(2-nitrobenzoic acid) provides a continuous assay for chymotrypsin as sensitive as any assay reported in the literature. Serine proteases which hydrolyze this substrate may be detected in polyacrylamide disc gels by incubation in the presence of nitro blue tetrazolium. Apparent Km values of 0.02 and 7 mM and kcat values of 37 S-1 and 126 S-1 were observed for the hydrolysis of BzTyrSBzl by alpha-chymotrypsin and subtilisin BPN', respectively. Additionally, 5 mM indole was observed to behave as a strict competitive inhibitor of the alpha-chymotrypsin-catalyzed hydrolysis of BzTyrSBzl but was observed to increase the maximal rate of hydrolysis of p-nitrophenyl acetate by alpha-chymotrypsin by 30%, as previously described. These data, the published data of other workers, and results from studies with molecular models of trypsin and subtilisin BPN' are used as the basis for describing more fully a secondary hydrophobic binding pocket on alpha-chymotrypsin. The pocket is immediately adjacent to the active site serine and is tentatively suggested to be composed of 4 aliphatic side chain residues and 2 glycine residues.

Benzyl Compounds↗

PubMed1994

Superoxide scavenging activity in leukocytes and absence of cellular toxicity of a series of coumarins.

Sixteen synthetic or plant-derived coumarins of dietary importance with different patterns of substitution were tested for their capacity to scavenge superoxide and for their cytotoxicity. Superoxide was generated by human polymorphonuclear leukocytes stimulated by phorbol myristate acetate and was measured using the reduction of ferricytochrome c or of nitrobule tetrazolium (NBT). Eleven of the coumarins, all lacking dihydroxy substitution, did not scavenge superoxide. Of the remaining five, the most potent scavenger was fraxetin (7,8-dihydroxy-6-methoxycoumarin) with an IC50 (concentration producing 50% inhibition) of 2.3 microM in the cytochrome assay and 5.8 microM using NBT. The other four coumarins (all containing ortho-dihydroxy catechol functions, and found previously to be pro-oxidant in cell-free systems by virtue of reduction of ferric to ferrous ions), themselves rapidly reduced cytochrome c. Therefore their effects on superoxide were measured using NBT, yielding IC50 values in the range 8.5 to 82.0 microM. Fraxetin and the other active and inactive coumarins were not directly cytotoxic at 100 microM to leukocytes or to erythrocytes, as shown by their failure to cause release of cytosolic lactate dehydrogenase or to cause haemolysis, respectively. However, all five dihydroxylated pro-oxidant coumarins were toxic to NS20Y neuroblastoma cells in 24 hr culture, whereas the other eleven coumarins were nontoxic. We conclude that 7,8-dihydroxylated coumarins such as fraxetin are agents which are not themselves directly cytotoxic and are capable of direct scavenging of superoxide anion radicals, an action which might be protective at sites of leukocyte activation during inflammation. However, in the presence of free ferric ions they may exert potentially damaging pro-oxidant actions, including cytotoxicity. This series of compounds provides a useful basis for structure-activity studies designed to achieve separation or combination of these properties.

Animals↗

PubMed2001

Antitumor activity of antisense clusterin oligonucleotides is improved in vitro and in vivo by incorporation of 2'-O-(2-methoxy)ethyl chemistry.

Phosphorothioate (P=S) antisense oligonucleotides (ASO) targeting the cell survival gene clusterin synergistically enhance castration- and chemotherapy-induced apoptosis in prostate cancer xenografts. This study compares efficacy, tissue half-lives, and toxicity of P=S clusterin ASO to third-generation backbone 2'-O-(2-methoxy)ethyl (2'MOE) ribose-modified clusterin ASO. Northern analysis quantified changes in clusterin mRNA levels in human PC-3 cells and tumors. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay measured effects of combined clusterin ASO plus paclitaxel on PC-3 cell growth. Athymic mice bearing PC-3 tumors were treated with paclitaxel plus either P=S clusterin ASO, 2'-MOE clusterin ASO, or mismatch control oligonucleotides for 28 days. Weekly body weights and serum parameters were measured to assess toxicity. Tissue half-life of P=S and 2'-MOE ASO in PC-3 tumors was assessed using capillary gel electrophoresis (CGE). Both 2'-MOE and P=S ASO decreased clusterin mRNA levels in a dose-dependent and sequence-specific manner. 2'-MOE ASO more potently suppressed clusterin mRNA (80 versus 40% at 500 nM) compared with P=S ASO. IC(50) of paclitaxel was equally reduced (50--75%) by both compounds. In vivo tissue half-life was significantly longer for 2'-MOE-modified ASO than for P=S ASO (5 versus 0.5 days). Using CGE, >90% of detected 2'-MOE ASO in tumor tissue was full length. Weekly administration of 2'-MOE clusterin ASO was equivalent to daily P=S clusterin ASO in enhancing paclitaxel efficacy in vivo. 2'-MOE-modified ASO potently suppressed clusterin expression and prolonged tissue half-lives with no additional side effects. These results support the use of 2'-MOE-modified ASO over conventional P=S ASO by potentially increasing potency and allowing longer dosing intervals in clinical trials.

Animals↗

PubMed2004

Influence of norcantharidin on proliferation, proliferation-related gene proteins proliferating cell nuclear antigen and Ki-67 of human gallbladder carcinoma GBC-SD cells.

BACKGROUND: Gallbladder carcinoma is a highly lethal and aggressive disease with early metastasis, strong invasion and poor prognosis. Most patients with this disease are at the advanced and un-resectable stage and should be considered for palliative treatment such as chemotherapy and radiotherapy. Unfortunately, reports of chemotherapy and radiotherapy for gallbladder carcinoma are disappointing. We investigated the influence of norcantharidin (NCTD) on proliferation, proliferation-related gene proteins PCNA and Ki-67 of human gallbladder carcinoma GBC-SD cells in vitro. METHODS: GBC-SD cell lines of human gallbladder carcinoma were cultured by the cell culture technique. The experiment was divided into NCTD group and control group. The tetrazolium-based colorimetric assay was used to evaluate cell growth. The streptavidin-biotin complex method was used to determine the expressions of proliferation-related gene proteins PCNA and Ki-67 of human gallbladder carcinoma GBC-SD cells. RESULTS: NCTD inhibited the growth and proliferation of GBC-SD cells from 10 mg/L or after 6 hours in a dose-and time-dependent manner, with the IC50 value of 56.18 microg/ml at 48 hours. After treatment with NCTD, the expression of PCNA (0.932+/-0.031 vs. 0.318+/-0.023, P<0.001) and Ki-67 (0.964+/-0.092 vs. 0.297+/-0.018, P<0.001) proteins were decreased significantly. CONCLUSION: NCTD inhibits the proliferation of human gallbladder carcinoma GBC-SD cells in vitro and the expression of their proliferation-related gene proteins PCNA and Ki-67.

Bridged Bicyclo Compounds, Heterocyclic↗

PubMed1984

Neutrophil function and infectious disease in workers occupationally exposed to phosphoorganic pesticides: role of mononuclear-derived chemotactic factor for neutrophils.

Neutrophil function and the prevalence of infections in 85 workers occupationally exposed to phosphoorganic pesticides were examined and compared to those of age- and sex-matched healthy controls. Activity of cholinesterase (ChE) in red blood cells (RBC) and in serum was used as marker of organophosphate toxicity. A decrease of CHE activity was observed in all groups of workers, both in serum and in RBC, and was dependent on the degree of exposure to the pesticides. A marked impairment of neutrophil chemotaxis stimulated with zymosan-activated serum (from workers or controls) was observed in all groups of workers. There was no significant change of polymorphonuclear neutrophil (PMN) migration after their preincubation in 10% autologous serum or washed cells. However, neutrophil chemotaxis was normal after stimulation with specific mononuclear-derived chemotactic factor (MDCF). The area of random migration increased in those working directly in the production of organophosphates. A decrease of adhesion and an increase of nitroblue tetrazolium-dye reduction was also found. The frequency of upper respiratory tract infection (in 68.8%) was greater in workers than in controls and similarly to their recurrence was dependent upon the time of exposure to the insecticides. A normal frequency of infections localized outside of the upper respiratory tract was observed. It may be concluded that (1) impairment of chemotaxis in the workers is not dependent on serum factors; (2) stimulation of neutrophil chemotaxis by MDCF occurs by a different mechanism to their stimulation by zymosan-activated serum; (3) the increase of morbidity in the workers is probably caused by prolonged inhalation of both the insecticides and solvents; (4) the impaired function of neutrophils may be not so important as expected. However, the local effects of the pesticides should be explored.

Adult↗

PubMed1983

Evaluation of some anthracycline antibiotics in an in vivo model for studying drug-induced human leukemia cell differentiation.

Human acute promyelocytic leukemia cells (HL-60) were induced to undergo terminal differentiation by treatment in vivo with marcellomycin. This was accomplished by cloning HL-60 cells in 0.3% agar in diffusion chambers, which were subsequently implanted in the peritoneal cavities of mice. These animals were given injections i.v. with anthracycline antibiotics, and the chambers were transferred to a second recipient 24 hr later. After an additional 8 days, the chambers were removed, the cloning efficiency was determined, and colonies were scored for the presence of differentiated cells based on their ability to reduce nitro blue tetrazolium (NBT). Marcellomycin produced dose-dependent decreases in cloning efficiency and increases in the number of differentiated cells present in chambers. At all dose levels of marcellomycin tested, three types of colonies were observed; these were colonies consisting entirely of undifferentiated cells and approximately equal numbers of colonies consisting of solely differentiated cells and those with mixtures of both differentiated and undifferentiated cells. An 8-fold increase in colonies containing differentiated cells (both pure and mixed) was observed after a single injection of marcellomycin (10 mg/kg), a dose which reduced cloning efficiency by 40%. At that dosage level, aclacinomycin A also induced differentiation, while doxorubicin was ineffective, a finding consistent with the effects of these anthracyclines on HL-60 cells in suspension culture. In addition to the functional changes accompanying differentiation, commitment was characterized by a limitation in proliferative potential. Thus, the average size of uniform NBT-positive colonies was approximately 16 cells, and few clones of NBT-positive cells greater than 32 cells in number were observed; this contrasted with NBT-negative clones which contained up to 100 cells. This finding suggests that HL-60 cells undergo an average of four and a maximum of five divisions upon commitment to granulocytic differentiation. The in vivo system described may be useful in further evaluation of differentiation-inducing agents for therapeutic potential after an initial in vitro screen to identify active compounds.

Aclarubicin↗

PubMed2006

Effectiveness of domestic antibacterial products in decontaminating food contact surfaces.

Four commercially available antibacterial products (two wipes and two sprays) were tested under laboratory conditions on a range of food contact surfaces (wood, glass, plastic, Microban incorporated plastic). The products' effectiveness at preventing cross-contamination of Escherichia coli and Staphylococcus aureus and the influence of surface type and drying time were assessed. Survival of the bacterial culture (approximately 400 colonies per 8 cm(2)) on the above preparation surfaces was determined using an in situ nitroblue tetrazolium (NBT) method. In the absence of any antibacterial products, both bacteria survived up to 120 min on all test surfaces with glass and plastic showing no reduction in bacterial number. The order of survival is: glass>plastic>>Microban incorporated plastic>wood (<8%). The length of drying time did not affect the survival of either bacterium on glass and plastic surfaces. On wood and Microban incorporated plastic, E. coli appeared to be more sensitive to drying time than S. aureus. Only plastic appeared to affect the effectiveness of the antibacterial products, where the reduction in bacterial number was significantly lower than the other test surfaces (p<0.05). The overall results suggest the antibacterial products are effective in disinfecting food preparing surfaces, provided products instructions are carefully followed.

Anti-Bacterial Agents↗

PubMed1998

Growth inhibitory effect of lithium gammalinolenate on pancreatic cancer cell lines: the influence of albumin and iron.

Essential fatty acids, especially gamma linolenic (GLA) and eicosapentaenoic acids, have been proposed as potential anticancer drugs. Our aim was to study the effect of the lithium salt of gamma linolenic acid (LiGLA) on the growth of two human pancreatic cancer cell lines (MIA PaCa2 and Panc 1) and primary human fibroblasts (HFF 5) in vitro. Cell growth was assessed by a microculture tetrazolium (MTT) assay. LiGLA had a selective growth inhibitory effect on pancreatic cancer cell lines with 50% growth inhibition (IC50) at approximately 6-16 mumol/l compared with approximately 111 mumol/l for the fibroblasts. The degree of growth inhibition increased with the time of exposure to LiGLA. Special attention was paid to the influence of albumin and iron on LiGLA-mediated growth inhibition. Albumin incorporated into essentially serum-free culture medium inhibited the effect of LiGLA in a dose-dependent manner, associated with reduced GLA uptake by cancer cells. Ferric ions were confirmed as potentiators of the growth inhibitory effect of LiGLA but more physiologically relevant transferrin-bound iron was ineffective. With further improvements in the fatty acid delivery mechanism, LiGLA may become a useful adjunct in the management of pancreatic cancer patients.

Albumins↗

PubMed2001

Lineage switch induced by overexpression of Ets family transcription factor PU.1 in murine erythroleukemia cells.

PU.1 is an Ets family transcription factor essential for myelomonocyte and B-cell development. We previously showed that overexpression of PU.1 in murine erythroleukemia (MEL) cells inhibits growth and erythroid differentiation and induces apoptosis of the cells. In an effort to identify target genes of PU.1 concerning these phenomena by using a messenger RNA differential display strategy, we found that some myeloid-specific and lymphoid-specific genes, such as the osteopontin gene, are transcriptionally up-regulated in MEL cells after overexpression of PU.1. We then found that expression of several myelomonocyte-specific genes, including the CAAT-enhancer-binding protein-alpha and granulocyte-macrophage colony-stimulating factor receptor genes, was induced in MEL cells after overexpression of PU.1. B-cell-specific genes were also examined, and expression of the CD19 gene was found to be induced. Expression of the myelomonocyte-specific proteins CD11b and F4/80 antigen but not the B-cell-specific proteins B220 and CD19 was also induced. After overexpression of PU.1, MEL cells became adherent and phagocytic and showed enhanced nitroblue tetrazolium reduction activity. Expression of myelomonocyte-specific and B-cell-specific genes was not induced when a mutant PU.1 with part of the activation domain deleted (a change found to inhibit erythroid differentiation of MEL cells) was expressed. These results indicate that PU.1 induces a lineage switch in MEL cells toward myelomonocytic cells and that its activation domain is essential for this effect. The results also suggest that the pathway of the lineage switch is distinct from that of inhibition of erythroid differentiation in MEL cells.

Cell Adhesion↗

PubMed1984

Biodegradation of 4-nitrophenol in standardized aquatic degradation tests.

During the years 1978-1981 both the European Economic Community (the EEC) and the Organization for Economic Cooperation and Development (the OECD) organized various interlaboratory comparison programs on standardized screening methods to study the biodegradability of chemicals in water. While the ring test results were generally rather heterogenous, one of the compounds studied, 4-nitrophenol, turned out to be particularly problematic as the compound was found either easily biodegradable or not biodegradable by various laboratories in various tests. This paper describes some more detailed studies on 4-nitrophenol degradation in two different tests, the modified OECD screening test (MOST test) and the Zahn-Wellens test, respectively. The test variables investigated include inoculum characteristics and pretreatment, test duration, and 4-nitrophenol concentration. The results are discussed in relation to toxicity and degradation pathways of 4-nitrophenol. It is concluded that in order to improve the comparability of results from standardized aquatic biodegradation tests, test strategies should allow the option of performing a test with a preadapted inoculum in the event of negative test results with freshly collected inocula. Increasing the inoculated concentration of microorganisms in some tests may also contribute to the attainment of more consistent test results.

Biodegradation, Environmental↗

PubMed2004

A human and mouse pregnane X receptor reporter gene assay in combination with cytotoxicity measurements as a tool to evaluate species-specific CYP3A induction.

Recent studies have demonstrated that a member of the nuclear receptor family, pregnane X receptor (PXR) is a key regulator of the expression of cytochrome P450 3A (CYP3A) in humans and rodents. It is also known that species specificity in the induction of CYP3A by xenobiotics is likely a consequence of differences at the level of PXR activation. Because of the importance of CYP3A4 in drug metabolism, the development of rapid and accurate in vitro assays for predicting the effects of compounds on CYP3A4 expression or activity in humans has been a long-standing goal within pharmaceutical industries. PXR activation measurements using an in vitro reporter gene approach appears to provide a rapid and relatively inexpensive means for predicting whether compounds will induce CYP3A levels in vivo. In this study, using an HepG2 cell based human and mouse PXR reporter gene assay, 23 compounds were tested for their potential to activate hPXR or mPXR. Data demonstrated that potent activators of hPXR had virtually no activity on mPXR and efficient activators of mPXR had weak activity on hPXR. In addition, a third category of moderate/weak activators of both hPXR and mPXR was identified. Exemestane was a strong activator of mPXR ( approximately 22-fold activation) with only minor effect on hPXR ( approximately 5-fold activation). The importance of cell viability measurements as part of the PXR reporter gene assay was demonstrated as significant cytotoxicity or inhibition of cell proliferation might underestimate the potential for PXR activation.

Androstadienes↗

PubMed2005

Comparative activities of lipid esters of cidofovir and cyclic cidofovir against replication of herpesviruses in vitro.

Cidofovir (CDV) is an effective therapy for certain human cytomegalovirus (HCMV) infections in immunocompromised patients that are resistant to other antiviral drugs, but the compound is not active orally. To improve oral bioavailability, a series of lipid analogs of CDV and cyclic CDV (cCDV), including hexadecyloxypropyl-CDV and -cCDV and octadecyloxyethyl-CDV and -cCDV, were synthesized and found to have multiple-log-unit enhanced activity against HCMV in vitro. On the basis of the activity observed with these analogs, additional lipid esters were synthesized and evaluated for their activity against herpes simplex virus (HSV) types 1 and 2, human cytomegalovirus, murine cytomegalovirus, varicella-zoster virus (VZV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and HHV-8. Using several different in vitro assays, concentrations of drug as low as 0.001 microM reduced herpesvirus replication by 50% (EC50) with the CDV analogs, whereas the cCDV compounds were generally less active. In most of the assays performed, the EC50 values of the lipid esters were at least 100-fold lower than the EC50 values for unmodified CDV or cCDV. The lipid analogs were also active against isolates that were resistant to CDV, ganciclovir, or foscarnet. These results indicate that the lipid ester analogs are considerably more active than CDV itself against HSV, VZV, CMV, EBV, HHV-6, and HHV-8 in vitro, suggesting that they may have potential for the treatment of infections caused by a variety of herpesviruses.

Antiviral Agents↗

PubMed2002

Preparation of calcium aluminate cement for hard tissue repair: effects of lithium fluoride and maleic acid on setting behavior, compressive strength, and biocompatibility.

We investigated lithium fluoride (LiF) and maleic acid (MA) containing calcium aluminate cement (CAC) for hard tissue repair. The objective of this study is to estimate the addition effects of LiF and MA on setting behavior, compressive strength, and biocompatibility of CAC and to find the most compatible composition of LiF and MA for using CAC as a new bone cement. The CAC was composed mainly of CaO. Al(2)O(3). Samples of LiF and MA containing CAC were formed along with recording of setting time and peak temperature and then set cement was analyzed by X-ray diffraction (XRD). Agar diffusion test, tetrazolium bromide (MTT) assay, and hemolysis test were used to detect initial in vitro biocompatibility of LiF and MA containing CAC. It was revealed from the results that LiF shortened setting time and decreased compressive strength, whereas MA delayed setting time and increased compressive strength. However, LiF and MA showed no or little influence on maximum temperature of CAC. CAC containing 0.5 g of LiF and 8.75 g of MA showed the highest compressive strength (111.64 +/- 7.74 MPa) across all the experimental compositions. The CACs containing 0.5 g of LiF/8.75 g of MA and 1.01 g LiF/8.75 g of MA had no cytotoxicity and hemolysis. In this study, CAC with 0.5 g of LiF and 8.75g of MA showed the most compatible properties for using bone cement, and thus it was assessed a candidate for a new bone cement along with CAC.

Aluminum Compounds↗

PubMed2002

Mechanisms of idiosyncratic drug reactions: the case of felbamate.

Idiosyncratic drug reactions (IDR) are a specific type of drug toxicity characterized by their delayed onset, low incidence and reactive metabolite formation with little, if any, correlation between pharmacokinetics or pharmacodynamics and the toxicological outcome. As the name implies, IDR are unpredictable and often result in the post marketing failure of otherwise useful therapies. Examples of drugs, which have failed as a result of IDR in recent years, include trovafloxacin, zileuton, troglitazone, tolcapone and felbamate. To date there exists no pre-clinical model to predict these adverse drug reactions and a mechanistic understanding of these toxicities remains limited. In an attempt to better understand this class of drug toxicities and gain mechanistic insight, we have studied the IDR associated with a model compound, felbamate. Our studies with felbamate are consistent with the theory that compounds which cause IDR undergo bioactivation to a highly reactive electrophilic metabolite that is capable of forming covalent protein adducts in vivo. In additon, our data suggest that under normal physiological conditions glutathione plays a protective role in preventing IDR during felbamate therapy, further emphasizing a correlation between reactive metabolite formation and a toxic outcome. Clinical studies with felbamate have been able to demonstrate an association between reactive metabolite formation and a clinically relevant toxicity; however, additional research is required to more fully understand the link between reactive metabolite formation and the events which elicit toxicity. Going forward, it seems reasonable that screening for reactive metabolite formation in early drug discovery may be an important tool in eliminating the post-marketing failure of otherwise useful therapies.

Aldehyde Dehydrogenase↗

PubMed1994

Inhibition of long-chain acylcarnitine accumulation during coronary artery occlusion does not alter infarct size in dogs.

We tested whether inhibition of carnitine acyl-transferase-1 (CAT-1) during coronary artery occlusion can limit infarct size (IS) by suppressing accumulation of long-chain acylcarnitines (LCAs), potentially cytotoxic intermediates of fatty acid metabolism. The CAT-1 inhibitor 2-[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate (POCA) was administered to dogs before 90-min occlusion and 4-h reperfusion of the left anterior descending or left circumflex coronary artery (LAD, LCX). Dogs in the LAD occlusion series received 7.5 (n = 5) or 15 (n = 2) mg/kg POCA intravenously (i.v.); dogs in the LCX occlusion series received 15 mg/kg i.v. (n = 7); an equal number were treated with drug vehicle. Biopsies were obtained for determination of myocardial LCAs. The region at risk and IS were delineated by dye injection and tetrazolium staining. In vehicle-treated dogs, myocardial LCAs (in picomoles per milligram of wet weight +/- SEM) increased from 11 +/- 3 to a peak of 75 +/- 24 during LAD occlusion and from 32 +/- 10 to 192 +/- 55 during LCX occlusion. In POCA-treated dogs LCAs increased from 12 +/- 2 to only 33 +/- 13 pmol/mg wet weight during LAD occlusion (p < 0.05 vs. vehicle) and did not increase significantly during LCX occlusion; 22 +/- 8 to 27 +/- 5 pmol/mg wet weight (p < 0.005 vs. vehicle). LCX occlusion resulted in larger areas at risk and larger infarcts (as a percentage of left ventricle) than did LAD occlusion. IS as a percentage of the region at risk did not differ significantly among the experimental groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcarnitine↗

PubMed1993

Distribution of deoxyglucose and technetium-99m-glucarate in the acutely ischemic myocardium.

The regional myocardial distribution of 99mTc-glucarate was compared to 3H-deoxyglucose in 22 rabbits with left circumflex marginal artery occlusion. In 12 rabbits, tissue radioactivity measurements were compared to the results of triphenyl tetrazolium chloride staining and light microscopy. In 10 additional rabbits, the myocardial sodium space (24NaCl), an indicator of tissue edema induced by injury, was compared to the distribution of deoxyglucose and glucarate. Technetium-99m-glucarate accumulated in injured myocardium within 6 hr after coronary ligation and myocardial concentration was greatest in the most severely injured zones (TTC unstained). Hydrogen-3-deoxyglucose behaved as a marker of ischemia but concentrated in tissue with injury ranging from mild ischemia (TTC stained) to transmural infarction (TTC unstained). Both 99mTc-glucarate and 3H-deoxyglucose concentrated in acute, severely injured myocardial tissue. These studies suggest that 99mTc-glucarate is a useful tracer for evaluating myocardial injury. In addition, it appears that 99mTc-glucarate and 3H-deoxyglucose demarcate different points in the spectrum of myocardial injury.

Acute Disease↗

PubMed1986

Study of differentiation of fresh myeloid leukemic cells by physiologic agents that induce a human promyelocytic leukemic line (HL-60) to differentiate.

A promyelocytic cell line known as HL-60 can be induced to mature to granulocytes or monocytes after exposure to a variety of physiologic agents including 1-alpha 25 dihydroxy Vitamin D3 (Vit D), retinoic acid, cyclic AMP cell permeant compounds, and stimulators of adenylate cyclase. These compounds were used in primary culture of blast cells from 12 patients with acute nonlymphocytic leukemia. Maturation was assessed by morphology, superoxide production, development of esterase activity and chemotactic peptide receptor expression. Morphologic maturation and superoxide production correlated with chemotactic peptide receptor expression. The majority of blast cells treated with inducer showed no significant change in morphologic or functional markers compared to the blast cells cultured in fresh media alone. Chemotactic peptide receptor expression increased 3 to 30-fold in 13 of 14 cases studied. In 4 patients, the highest receptor expression was without inducer and in 4 patients the highest increase was with dibutyryl cyclic AMP treatment. Our study suggests that physiologic inducers of HL-60 differentiation do not consistently have the same effect on primary suspension culture of freshly isolated human leukemia cells.

Bucladesine↗

PubMed1997

Silicone rubber-hydrogel composites as polymeric biomaterials. IX. Composites containing powdery polyacrylamide hydrogel.

A composite material has been prepared consisting of a silicone rubber matrix and particulate lightly cross-linked polyacrylamide hydrogel. The material, resembling common silicone rubber, is hydrophilic and swells in water like hydrogels. The polyacrylamide has a high specific surface area, a relatively low content of water-soluble low-molecular-weight compounds and, owing to its non-ionogenic character, a pH-independent swelling degree. For the composite material consisting of the silicone rubber and very fine powdery cross-linked polyacrylamide, we have measured the rate of swelling in water, the mechanical properties (tensile strength, break elongation, hardness, resilience), biological properties (implantation test, cytotoxicity, cell cultivation) and UV absorption of its water extracts. The polyacrylamide and polysiloxane purity, as the composite material starting components, has been determined to be satisfactory. As a result, a high swelling rate of the prepared composite material has been observed, resulting in reaching more than 70% wt of water of the equilibrium swelling. The results show that the composite material is suitable for biological and medical use.

3T3 Cells↗