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Biomedical subjects

B E Cham

Publications and source records attributed to B E Cham.

At least 37 records · Page 2Linked to original sources
PubMed1987

Glycoalkaloids from Solanum sodomaeum are effective in the treatment of skin cancers in man.

A cream formulation containing glycoalkaloids purified from the plant species Solanum sodomaeum L. is effective in the treatment of the malignant human skin tumours; basal cell carcinomas (BCCs), squamous cell carcinomas (SCCs) and the benign tumours; keratoses and keratoacanthomas. Histological analyses of biopsies taken before, during and after treatment give compelling evidence of the efficacy of the formulation. The treated lesions did not recur for at least 3 years after cessation of therapy. The observed complete regressions were; 20/24 for the BCCs; 5/6 for the SCCs; 23/23 for the keratoses; and, 9/9 for the keratoacanthomas. Biochemical, haematological and urinanalytical studies demonstrated that there were no adverse effects on the liver, kidneys or haematopoietic system during treatment. Normal skin treated with the formulation likewise was free from adverse histological or clinical effects. The data indicate that glycoalkaloids of this type are therefore potentially useful in the treatment of several types of human skin cancers.

Aged↗
PubMed1986

Lipid associated tissue ferritin.

Delipidation of liver homogenates, using an organic solvent system which does not denature proteins, increases measurable ferritin by 25-33%, compared to ferritin concentrations by standard heat supernatant assays. When applied to polyacrylamide gradient gels, lipid-associated ferritin does not enter the gel but after delipidation, this ferritin co-migrates with cytosolic ferritin and with purified liver ferritin. The biological significance of the association of ferritin with lipid has yet to be examined.

Animals↗
PubMed1985

A procedure for the purification of ferritin from human liver by heating a methanol-treated homogenate.

A simple, rapid technique for purification of ferritin from human liver tissue is described. Methanol, at a final concentration of 40% (v/v) in liver homogenate, precipitates the majority of proteins but does not affect ferritin. Subsequent heating of this homogenate at 75 degrees C for 10 min results in a purified ferritin preparation as judged by immunoelectrophoresis and polyacrylamide gel electrophoresis. The resultant purified ferritin contained the same amount of iron as the original endogenous ferritin. There were no significant differences (paired t tests) in the amount of protein in the purified ferritin preparation when measured by rocket immunoelectrophoresis and by the Lowry procedure, suggesting that the antigenecity of ferritin was unaffected by the methanol and heat treatment. Both endogenous liver ferritin and radiolabeled human liver ferritin added to liver homogenates were recovered after methanol and heat treatment with similar yields (77 +/- 7% and 70 +/- 2%, respectively) when compared with the standard treatment of heating a homogenate at 75 degrees C. The overall ferritin yield with this rapid procedure was 40%.

Chromatography, High Pressure Liquid↗
PubMed1983

Tissue ferritin in scorbutic guinea-pigs.

Tissue ferritin metabolism was compared in control and ascorbic acid (AA) deficient guinea-pigs. Concentrations of ferritin protein in the liver (0.98 +/- 0.61 mg/g wet weight) and spleen (0.48 +/- 0.23 mg/g) of control animals did not change after tissue depletion of AA. Iron dextran (75 mg/kg weight, i.m.) caused a 4-5-fold increase in tissue ferritin concentrations in controls whereas no increase in tissue ferritin occurred in scorbutic animals. The rise in tissue total iron concentration was similar in the two groups. Liver ferritin synthesis was similar in control and scorbutic animals. After stimulation with iron (8 mg/kg iron dextran i.v.), ferritin synthesis rose in both groups of animals. However, the pattern of response differed. At 24 h after iron dextran, ferritin synthesis in controls was still significantly elevated (P less than 0.001) and liver ferritin protein continued to rise, whereas in scorbutic animals, ferritin synthesis had declined to pre-iron injection levels, and no rise in ferritin protein values occurred. It is concluded that the ferritin synthetic apparatus in AA deficient tissues remained intact and capable of responding to added iron. The absence of a sustained elevation in tissue ferritin protein after an iron load appeared to be due to inadequate stimulation of ferritin synthesis by intracellular iron. It is suggested that AA has a physiological role in the reduction of intracellular iron and that it is the reduced form of iron which stimulates ferritin synthesis. Abnormalities of iron metabolism occur in AA depleted tissues when the quantity of Fe3+ entering cells exceeds the residual reducing capacity of those cells.

Animals↗
PubMed1982

Plasma levels of aspirin following effervescent and enteric coated tablets, and their effect on platelet function.

Single doses of effervescent tablets (1200 mg) and enteric coated (EC) tablets (1300 mg and 650 mg) of acetylsalicylic acid (aspirin, ASA) were given to healthy volunteers in random order. Plasma ASA and salicylic acid (SA) levels were measured and concurrent in vitro measurements of the volunteers' platelet aggregation were carried out. The effervescent preparation resulted in peak ASA concentrations of 17-40 mg/l, achieved 20 to 30 min after a 1200 mg dose, whereas peak ASA levels of 0.01-0.37 mg/l were observed 4-6 h after a 650 mg dose of the EC preparation. With all the aggregating agents that were added to the test system maximum inhibition of platelet aggregation (about 50% of pre dose levels) was seen 1.0 h after the effervescent ASA dose, and persisted to at least 24 h, but with the EC preparation not until 24 h, at which time the degree of inhibition was also about 50% of pre-dose levels. A 1.0 g dose of sodium salicylate had no effect on in vitro platelet function. It was concluded that mean plasma levels of ASA of less than 0.25 mg/l are sufficient to depress aggregation by approximately 50%. A low dose of ASA taken daily either as effervescent ASA or EC ASA, significantly inhibits platelet aggregation and so may reduce the risk of ischaemic episodes in susceptible patients.

Adult↗
PubMed1982

In vivo and in vitro studies on the binding of salicylate to human plasma proteins: evidence for one type of binding site.

In vivo and in vitro binding of salicylate to plasma proteins was studied by ultrafiltration at room temperature. The nonlinearity of the Scatchard and Klotz plots were explained by the presence of lipid-soluble substances in plasma. Delipidation of plasma resulted in changes of the binding characteristics of plasma in that more moles of salicylate could be bound per mole of protein. This changed the appearances of the Scatchard and Klotz plots so that a much larger range of salicylate concentration could be accommodated by the linear portion of the graphs. The equilibrium constant for the in vitro salicylate binding was identical for the delipidated and untreated plasma. However, the in vivo binding constant for salicylate in plasma was higher than the in vitro binding constant.

Adult↗
PubMed1981

Salicylate metabolite kinetics after several salicylates.

Single oral doses of aspirin (ASA, 1,500 mg), sodium salicylate (NaSA, 1,500 mg, 1,200 mg), and salicyluric acid (SUA, 500 mg) were given to five subjects. Serial plasma and urine samples were collected for 24 hr (plasma) and up to 48 hr (urine); salicylic acid (SA), SUA, and gentisic acid (GA) were measured by high-pressure liquid chromatography. The plasma concentration/time profiles for SUA after ASA and NaSA were fitted to the empirical equation CpSUA = A-Bt-Ce-alpha t -- (A-C)e-beta t. Michaelis constants (Vm and Km) for the conversion of SA to SUA were calculated from the equation (formula see text), where Cl is the renal clearance of SUA, ke is the rate constant of elimination of SUA, CpSA is the plasma concentration of salicylic acid. The term Cl (formula see text) is the estimated rate of formation of SUA from SA at any time (t). The calculated values (mean +/- SD) of Vm, Km, and Kmf (Km in terms of unbound SA) were 43.4 +/- 10.1 mg SA/hr, 14.3 +/- 3.4 mg SA/l plasma, and 0.75 +/- 0.15 mg unbound SA/l plasma. The Vm values were in accord with those reported, but the value for Km was considerably lower. Renal clearances of SUA and GA were 340 +/- 51 and 65 +/- 10 ml/min.

Adult↗
PubMed1980

Measurement and pharmacokinetics of acetylsalicylic acid by a novel high performance liquid chromatographic assay.

Plasma acetylsalicylic acid and salicylic acid are assayed by a specific, rapid, and sensitive high performance liquid chromatographic procedure. The plasma samples are treated with physostigmine to inhibit esterase activity that otherwise will promote enzymatic hydrolysis of acetylsalicylic acid to salicylic acid. Conditions are chosen such that the total in vitro hydrolysis of acetylsalicylic acid is minimized to less than 5%. Plasma samples are deproteinated with methylcyanide. Acetylsalicylic acid and salicylic acid are separated by elution with a mixture of methanol, acetic acid, and water on a reversed-phase octadecyl silane column and detected by ultraviolet absorption. Quantitation is achieved by measuring absolute peak heights. Recovery and repeatability studies are good. No interference was observed when 50 drugs were also present in the various plasma samples. Concentrations of acetylsalicylic acid and salicylic acid can be obtained within 20 min of receipt of the blood specimens. Pharmacokinetic parameters obtained by this method after a single oral dose of 900 mg soluble, effervescent acetylsalicylic acid in normal healthy subjects suggest that absorption, distribution, and elimination of acetylsalicylic acid are rapidly occurring events.

Aspirin↗
PubMed1980

High performance liquid chromatographic assay of dexamethasone in plasma and tissue.

Dexamethasone in plasma and in tissue is specifically quantitated by high performance liquid chromatography (ultraviolet detection at 254 nm) with an octadecyl silane reversed-phase chromatographic column employing peak-height ratio determination (internal standard, cyheptamide). The sample is first washed with heptane under alkaline conditions. The dexamethasone is then extracted from the washed sample with dichloromethane containing the internal standard. Dichloromethane is evaporated to dryness, and the concentrated extract is dissolved in tetrahydrofuran and then injected into a high performance liquid chromatograph. Dexamethasone and internal standard are eluted with a mixture of acetic acid, methanol, butanol, and water (11/19/30/440 by volume). Sensitivity limit is 10 ng, with linear response to at least 1.000 mg/liter plasma. Analytical recovery of dexamethasone from plasma is almost complete, and approximately 87% dexamethasone is recovered from brain tissue. Intra-assay precision (CV) is 1.07% (N = 11), and interassay precision is 1.38% (N = 5). No interference occurred in plasmas from patients treated with various drugs other than dexamethasone. Dexamethasone was estimated in plasma and in tumor tissue from patients on dexamethasone therapy.

Administration, Oral↗
PubMed1980

Simultaneous liquid-chromatographic quantitation of salicylic acid, salicyluric acid, and gentisic acid in urine.

We have developed a specific and sensitive method for the determination of salicylic acid, salicyluric acid, and gentisic acid in urine. Any proteins present are precipitated with methyl cyanide. After centrifugation, an aliquot of the supernate is directly injected into an octadecyl silane reversed-phase chromatographic column, then eluted with a mixture of water, butanol, acetic acid, and sodium sulfate, and quantitated at 313 nm by ultraviolet detection according to peak-height ratios (with internal standard, o-methoxybenzoic acid) or peak heights (no internal standard). The method allows estimates within 25 min. Sensitivity was 0.2 mg/L for gentisic acid, and 0.5 mg/L for both salicyluric and salicylic acid (20-micro L injection volume); response was linear with concentration to at least 2.000 g/L for salicylic acid and metabolites. Analytical recovery of salicylic acid and metabolites from urine is complete. Intra-assay precision (coefficient of variation) is 5.52% at 7.5 mg/L for salicylic acid, 5.01% at 9.33 mg/L for salicyluric acid, and 3.07% at 7.96 mg/L for gentisic acid. Interassay precision is 7.32% at 7.51 mg/L for salicylic acid, 5.52% at 8.58 mg/L for salicyluric acid, and 3.97% at 8.32 mg/L for gentisic acid. We saw no significant interference in urine from patients being treated with various drugs other than aspirin.

Aspirin↗
PubMed1978

Importance of apolipoproteins in lipid metabolism.

Lipids, which serve as a source of energy and are an important constituent of cell membrane structure, are readily stored in the body. By definition they are insoluble in water. Specific proteins called apolipoproteins interact with lipids to form soluble lipid-protein complexes called lipoproteins. It is in this form that the major lipids--cholesterol, triglyceride and phospholipid--circulate in plasma. Unesterified fatty acids, another major lipid group, are bound to albumin in the circulation. The plasma lipoproteins are complex macromolecules composed of lipids, apolipoproteins and carbohydrates. The relative proportions of these components differ markedly between lipoprotein classes. Hyperlipidemia is a term used for increased concentrations of plasma cholesterol and/or triglycerides. Any one plasma lipid is present in several types of lipoproteins. Thus, hyperlipidemia implies the presence of hyperlipoproteinemia. The latter has important therapeutic implications. Most of the recent attempts at classification have been directed at the lipoprotein level of plasma lipid organization. Decreased concentrations of lipids in plasma can be achieved by altering the rates of metabolism of lipoproteins. Decrease in lipoprotein synthesis, increased catabolism or impaired release from cells into the blood stream may all result in a decrease of plasma lipids. Drugs which affect one or more of these factors are used to treat hyperlipoproteinemia. In order to elucidate the mechanism of action of hypolipidemic drugs it is necessary to understand the lipoprotein defect at the molecular level. This requires a more detailed knowledge of lipoprotein metabolism than is presently available for most of the hyperlipoproteinemias. This paper will review some of the generally accepted properties of the plasma lipoproteins, describe some difficulties which hamper the understanding of lipoprotein metabolism, and identify possible mechanisms by which drugs may affect lipoprotein metabolism.

Apolipoproteins↗
PubMed1976

In vitro partial relipidation of apolipoproteins in plasma.

In vitro recombination of lipids with apolipoproteins is achieved when a concentrated solution of plasma lipids in petroleum ether is mixed with delipidated plasma. Combination of phospholipids and unesterified fatty acids are observed in amounts comparable with those originally present in the native unextracted plasma; triglycerides combine partially and cholesterol only slightly. On agarose gel immunoelectrophoresis, a component in the delipidated plasma which is reactive with high density lipoprotein antibodies migrates more slowly than high density lipoprotein in the undelipidated control plasma. However, the component reacting with low density lipoprotein antibodies in the delipidated plasma moves more rapidly than low density lipoprotein in the native plasma. These changes are reversed by recombination of lipid with delipidated plasma. All lipids present in the plasma phase after relipidation travel with the lipoproteins during zonal electrophoresis. The apparent concentrations of proteins reacting with high density and low density lipoprotein antibodies decrease when no lipid is present in plasma on assay by single radial immunodiffusion and immunoelectrophoresis, using commercially available lipoprotein antibodies. On relipidation, full immunochemical properties of high density lipoprotein are restored, but relipidated low density lipoprotein exhibits only partial immunochemical restoration.

Apolipoproteins↗
PubMed1976

Changes in electrophoretic mobilities of alpha-and beta-lipoproteins as a result of plasma delipidation.

A two-phase system containing the ternary mixture butanol/disopropyl ether/plasma in different proportions yields ordered delipidation of alpha-lipoproteins, pre-beta-lipoproteins- and beta-lipoproteins in plasma, as quantitated by densitometry after electrophoresis. As a consequence of delipidation the electrophoretic mobilities of pre-beta-lipoproteins and beta-lipoprotein increased, that of alpha-lipoprotein decreased.

Cholesterol↗