Biomedical subjects
Publications and source records attributed to M A Hanna.
The risk of perioperative cardiac morbidity and mortality can be predicted based on clinical assessment and noninvasive testing for the detection of myocardial ischemia. Appropriate preoperative interventions in high-risk patients are indicated. Medical intervention with beta blockade is particularly effective.
Composting of extruded poly(lactic acid) (PLA) in combination with pre-composted yard waste in a laboratory composting system was studied. Yard waste and PLA mixtures containing 0%, 10%, or 30% PLA (dry weight basis) were placed in composting vessels for four weeks. Exhaust gases were analyzed for carbon dioxide concentration twice per week. After the first week, significantly greater (P < 0.05) amounts of carbon dioxide were generated in vessels with 10% or 30% PLA than in control (0% PLA) vessels. Data indicated that microbial degradation of PLA occurred. There was no significant difference (P > 0.05) in carbon dioxide emission between 10% and 30% PLA mixtures. Compost pH dropped (from 6.0 to 4.0) after 4 weeks of composting for 30% PLA, but remained unchanged (6.3) for 0% or 10% PLA. Most likely, in the case of 30% PLA, substantial chemical hydrolysis and lactic acid generation lowered the compost pH. The lowered pH likely suppressed microbial activity, thus explaining the lack of difference in carbon dioxide emissions between 10% and 30% PLA mixtures. Gel permeation chromatography showed a notable decrease in PLA molecular weight as a result of composting. It was demonstrated that PLA can be efficiently composted when added in small amounts (<30% by weight) to pre-composted yard waste.
Regular (25% amylose) and waxy corn starches blended to various ratios with Eastar Bio Copolyester 14766 (EBC) were extruded into loose-fill foams using a twin screw extruder. Included in this study were two types of corn starch, three levels of EBC content, and three levels of starch moisture content. Waxy starch produced foams with greater radial expansions and lower unit and bulk densities than regular starch. Regular starch foams had lower water solubility indices (WSIs) than waxy starch foams. Foams made of both types of starch possessed similar mechanical properties. No differences were observed in compressibilities and spring indices of either waxy or regular starch foams. Higher levels of EBC addition resulted in less radial expansion and higher unit and bulk densities. Foams made with 10% EBC had higher compressibility than foams containing 25% EBC. Spring indices of single-piece samples and compressibilities and spring indices of bulk samples were not affected by the differences in the level of EBC addition. At 19% and 22% of moisture contents, foams had greater radial expansion than at 25% moisture content. Unit and bulk densities were not affected by variations in moisture content. At 22% moisture content, a lower WSI of 18.5% was obtained. At 22% moisture content, softer foams were produced. At all three levels of moisture content, no differences were detected in the spring indices.
Protein solubility (PS) values of different soy protein isolate (SPI) films were determined in water, 0.01 N HCl, 0.01 N NaOH, 4 M urea, and 0.2 M 2-mercaptoethanol. Tensile and color (L, a, and b values) properties of films also were determined. Control films were cast from heated (70 degrees C for 20 min), alkaline (pH 10) aqueous solutions of SPI (5 g/100 mL of water) and glycerin (50% w/w of SPI). Additional films were cast after incorporation of dialdehyde starch (DAS) at 10% w/w of SPI or small amounts of formaldehyde in the film-forming solutions. Also, control film samples were subjected to heat curing (90 degrees C for 24 h), UV radiation (51.8 J/m(2)), or adsorption of formaldehyde vapors. PS of control films was highest (P < 0.05) in 2-mercaptoethanol, confirming the importance of disulfide bonds in SPI film formation. All treatments were effective in reducing (P < 0.05) film PS in all solvents. Both DAS and adsorbed formaldehyde rendered the protein in films practically insoluble in all solvents. Adsorption of formaldehyde vapors and heat curing also substantially increased (P < 0.05) film tensile strength from 8.2 to 15.8 or 14.7 MPa, respectively. However, heat curing decreased (P < 0.05) film elongation at break from 30 to 6%. Most treatments had small but significant (P < 0.05) effects on b color values, with DAS-containing films having the greatest (P < 0. 05) mean b value (most yellowish). Also, DAS-containing, heat-cured, and UV-irradiated films were darker, as evidenced by their lower (P < 0.05) L values, than control films. It was demonstrated that PS of SPI films can be notably modified through chemical or physical treatments prior to or after casting.
The effects of extrusion cooking on the stability of zearalenone (ZEN) in spiked (4.4 microg/g) food-grade corn grits were investigated using a twin screw extruder. A ground rice culture material containing a high level of ZEN was used to spike the corn grits. The extrusion variables were screw type (mixing and nonmixing), temperature (120, 140, and 160 degrees C), and moisture content (18, 22, and 26%). Both unextruded and extruded samples were analyzed for ZEN by high-performance liquid chromatography. Extrusion cooking of the corn grits resulted in significant reductions of ZEN in grits extruded with either mixing screws or nonmixing screws, but use of mixing screws was somewhat more effective (66 to 83%) overall than nonmixing screws (65 to 77%). Greater reduction of ZEN was observed at either 120 or 140 degrees C than at 160 degrees C. The moisture content of corn grits was not a significant factor affecting reduction of ZEN during extrusion with either mixing or nonmixing screws.
The effects of high-temperature and -pressure processing of foods spiked with deoxynivalenol (DON) were examined. In extruded corn grits, extruded dry dog food, and autoclaved moist dog food, there were no significant reductions (P < 0.05) in DON after processing. Autoclaved cream-style corn showed a reduction in DON of only 12%. Overall, DON was stabile to the high temperature and pressure processes tested. The use of an alpha-amylase in the extraction method for analysis by an enzyme-linked immunosorbant assay (ELISA) improved the recovery of DON from the spiked extruded and autoclaved products by as much as 26% over the standard ELISA method.
Commercially available corn starches containing 0, 25, 50 and 70% amylose were extruded with 10, 20 and 30% soy protein isolate (SPI) or wheat gluten (WG) at 22% moisture content (dry basis) in a C.W. Brabender single screw laboratory extruder using a 140 degrees C barrel temperature and a 140 rpm screw speed. True, solid and bulk densities; percent total, closed and open pores; and shear strengths of the extrudates were determined. The microstructures of the extrudates were studied by scanning electron microscopy (SEM). The total pores of the extrudates were affected significantly (p > F = 0.0001) by type of protein (SPI or WG) and starch amylose. The open or closed pores, were affected by protein type only. The interaction between amylose and protein contents was highly significant (p > F = 0.0001). In general, the total pores and bulk densities were higher for WG-starch extrudates compared to SPI-starch extrudates. These values decreased as amylose content increased from 0 to 25% and then increased thereafter. The open pores, on the other hand, increased with increasing protein content from 10 to 20% and then decreased. Extrudates containing WG had higher shear strengths than those containing SPI.
6-(omega-Bromoacetyl)-2,3-diphenyl-5-methoxybenzofuran derivative (2) was synthesized and allowed to react with different reagents to get new benzofuran derivatives that are substituted with isolated or fused heterocyclic ring systems. The antimicrobial activity of the hitherto synthesized products was tested and evaluated.
Several new isolated or fused heterocyclic ring systems that accomodate the isothioureido functionality, often associated with immunosuppressive activity, were synthesized for possible use as immunosuppressive agents. Preparation of these anchored heterocycles was achieved via a multi-step synthesis starting with the key intermediate thiazolyl thiourea derivative (I). Structure of the newly synthesized products was confirmed using both of elemental and spectral analyses.
Four series of 5-(pyrazol-3-yl)thiadiazole and oxadiazole derivatives (Va-c, VIa-c, VIIIa-c, IXa-c) have been synthesized from 5-arylazo-3-carbethoxy-4-methoxy-1-phenylpyrazole (Ia-c) with a view to investigate their pharmacological activity. The structure of the synthesized products was inferred from elemental and spectral data. The hypoglycemic effect, antimicrobial activity and toxicity of these potential chemotherapeutic agents were evaluated. Nineteen of these products were effective, when administered at an oral dose of 100 mg/kg body weight in inducing a marked reduction in blood glucose level.
Some novel sulfonate ester-containing mono-, bi- and tricyclic fused ring systems (IV, Xa,b, XIa,b, XIV and XV) together with their precursors I, II and III were synthesized with a view to evaluating their efficacy as new sulfur-containing fungitoxic agents. The structures of the named compounds were established from elemental and spectral analyses.
Two series of substituted benzenesulphonamides (Va-e and VIa-e) have been synthesized from 4-methoxycarbonyl-1-[p-(acetylamino)benzenesulphonylimino]pyridini um ylide (II) with a view to investigate their pharmacological activity. The structure of the synthesized products was inferred from elemental and spectral data. The hypoglycemic effect, antimicrobial activity and toxicity of the possible chemotherapeutic agents were evaluated. Six of these products were effective, when administered at an oral dose of 100 mg/kg b. wt., inducing marked reduction in blood glucose level.
Two series of sulphanilamide derivatives (Va-i and Vla-i), comprising both azomethine and arylsulphonamidotetrahydropyridine moieties, were especially synthesized to investigate the additive effect of such moieties on the pharmacological activity of the produced sulphonamides as possible therapeutic agents for producing hypoglycemia. Most of the hitherto prepared sulphanilamide derivatives, exhibited marked hypoglycemic activity. Structure-activity relationships were investigated and discussed, not only on the basis of lipophilic (pi) and/or electronic (sigma) characters of the aromatic substituent (R), but also in light of a steric effect in these molecules. The structure of the newly synthesized compounds was inferred from elemental and spectral analysis.
A new series of substituted alpha-picolinium p-dimethylaminobenzalhydrazine derivatives and their o-hydroxy analogues has been prepared for evaluation of their efficacy as potential hypoglycemic agents. The synthesis was achieved by condensation of N-amino-alpha-picolinium perchlorate derivatives with the corresponding aromatic aldehydes. The structure of the synthesized products was inferred from elemental and spectral data. The hypoglycemic effect, antimicrobial activity and toxicity of the hitherto and possibly new chemotherapeutic agents were evaluated. Based on screening data, a possible structure-activity relationship has been discussed.
2-Aminoanthraquinone (1) was reacted with ethyl chloroformate to afford 2. The reaction between carbamate 2 and hydrazine hydrate gave semicarbazide 3, which on treatment with benzoic acid, phenyl isothiocyanate and carbon disulfide/potassium hydroxide furnished oxadiazoles 4, 6 and triazole 5, respectively. Also, treatment of 1 with chloroacetyl chloride gave chloroacetyl derivative 8. The reaction of glycolic acid, thioglycolic acid, diethyl malonate and malononitrile with 8 has been investigated. Compound 8 was treated with potassium thiocyanate to give 12, which was cyclized to 13a, while the reaction between 8 and potassium cyanate gave 13b directly. The structures of hitherto unknown compounds were confirmed by analytical and spectral methods. Some of the synthesized compounds were screened to test their antibacterial and antifungal properties.
Several ethyl 2,3-dioxohexanoate 2-arylhydrazone derivatives were obtained via coupling of the appropriate diazonium chlorides with ethyl butanoylacetate. Acetic acid-mediated cyclization of these products with N1-nicotinoyl and/or N1-(oxynicotinoyl)hydrazine derivatives gave a new series of 4-arylhydrazono-3-(n-propyl)-N1-nicotinoyl-2-pyrazolin-5-one s (Va-h) as well as their N1-(oxynicotinoyl) analogues (VIa-h). The structure of the prepared compounds was confirmed on the basis of elemental and spectral data. The hypoglycemic effect, antibacterial activity and toxicity of these agents were evaluated and discussed.
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Kinetic coefficients of friction for stainless steel, beta-titanium, nickel-titanium, and cobalt-chromium arch wires were measured on a smooth stainless steel or Teflon surface. A universal materials testing instrument was used to pull 0.017 X 0.025-inch rectangular arch wires through a pneumatically controlled binding surface. Classical friction relationships were evaluated by varying applied normal force--similar to ligature tie force--via this pneumatic control. Coefficients of friction were determined under dry and wet (artificial saliva) conditions. Frictional force values, and thus coefficients of friction, were found to increase with increasing normal force for all materials. Beta-titanium and stainless steel wires sliding against stainless steel, and stainless steel wire on Teflon consistently exhibited the lowest dry friction values. Artificial saliva increased friction for stainless steel, beta-titanium, and nickel-titanium wires sliding against stainless steel. Artificial saliva did not increase friction for cobalt chromium, stainless steel sliding against stainless steel, or stainless steel wire on Teflon compared to the dry condition. Stainless steel and beta-titanium wires sliding against stainless steel and stainless steel wire on Teflon showed the lowest friction values for the wet condition.