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Biomedical subjects

J De Beer

Publications and source records attributed to J De Beer.

12 recordsLinked to original sources
PubMed2001

Sequential bilateral total knee arthroplasty under 1 anesthetic in patients > or = 75 years old: complications and functional outcomes.

The objectives of this study were to determine the perioperative surgical and medical risks associated with sequential bilateral total knee arthroplasty (TKA) in patients > or = 75 years old and to assess their functional status and overall level of satisfaction at follow-up. Study participants were 82 consecutive patients > or = 75 years old who underwent a sequential bilateral TKA and 82 matched patients who underwent a unilateral TKA. There were 46 postoperative complications in the bilateral TKA group compared with 27 in the unilateral TKA group (P = .003). Postoperative cardiovascular complications were significantly greater in the sequential bilateral TKA group and were associated significantly with preoperative cardiovascular comorbidity. The mean Modified Hospital for Special Surgery knee score was rated as good (mean, 63.5 out of 80), and 95% of patients rated their knees as excellent or good at follow-up. Sequential bilateral TKA in patients > or =75 years old results in high patient satisfaction and good functional status at follow-up; however, there is an increased risk of cardiovascular complications during the postoperative period in bilateral sequential TKA patients when compared with a matched cohort of unilateral TKA patients.

Age Factors↗
PubMed2000

Cadmium and lead concentrations in acid food simulants: the values of validation parameters are predominantly affected by interspecific differences of utensils.

The obvious toxicity of cadmium and lead is at the basis of compulsory concentration determinations for lixiviation solutions of ceramic and earthenware household receptacles such as cups, plates, bowls and others. Concentrations in the food simulant which exceed 0.100 +/- 0.005 mg Cd dm-2 and 1.00 +/- 0.05 mg Pb dm-2 for flat receptacles, 0.500 +/- 0.025 mg Cd l-1 and 5.00 +/- 0.25 mg Pb l-1 for low volume (< 5 l) receptacles and 0.250 +/- 0.025 mg Cd l-1 and 2.50 +/- 0.25 mg Pb l-1 for high volume (> 5 l) receptacles are not acceptable and measures were taken by the EU member state authorities to enforce these norm concentrations. Generally, the uncertainty on the results forwarded by the legislation amounts to 5%. This value does not at all match the pronounced variability observed for several 'identical' trade samples, but rather represents the inherent variability of spectrometric analyses alone. Considering that the coefficients of variation can be as high as approximately 30%, either the ranges of acceptable concentrations or the maximal allowable concentrations should be corrected. Aware of the negative health effects of heavy metal contamination and of the risk increase due to dietary intake, a downward adjustment of the acceptable concentration ranges to 0.07 mg Cd dm-2 +/- 12%, 0.30 mg Cd l-1 +/- 12% and 0.10 mg Cd l-1 +/- 12% and to 0.8 mg Pb dm-2 +/- 13%, 4.0 mg Pb l-1 +/- 13% and 1.50 mg Pb l-1 +/- 13% is suggested.

Cadmium↗
PubMed1999

Nested designs in ruggedness testing.

Nested designs were performed in order to execute a ruggedness test according to the United States Pharmacopeia definition for ruggedness, in which mainly non-procedure related factors are examined. Several nested designs have been executed on a high performance liquid chromatography assay to determine tetracycline and related substances in bulk samples of tetracycline. Factors such as different laboratories, analysts, instruments, columns, days and batches were examined. The interpretation methods described in the literature were found to cause problems. In these methods the variances of the examined factors are estimated from the calculated mean square values and from the equation for the expected mean squares. Very frequently, negative variance estimates were obtained. Their absolute values were found to be dependent on the influence of the factor examined below it in the design, on the examined response. Therefore an alternative interpretation method for nested designs, based on pooled variances, was proposed and found to be appropriate to use for ruggedness testing purposes. Both approaches, the one from the literature and the one proposed here, were tested on simulated data coming from a nested design with four factors and on the experimentally measured data.

Analysis of Variance↗
PubMed1996

Ruggedness tests on the high performance liquid chromatography assay of the United States Pharmacopoeia 23 for tetracycline.HCl: comparison of different columns in an interlaboratory approach.

Ruggedness tests were performed on the United States Pharmacopoeia assay for tetracycline.HCl to examine problems previously reported in the literature. The experiments were performed on nine different columns. The effects of four factors selected from the procedure were examined on qualitative responses by performing half-fraction factorial designs at three different ages on each column. The influence of column ageing was separately evaluated by injections under nominal method conditions at different ages. The C-8 columns gave a separation that was as good as, or better than, the C-18 ones and were less influenced by ageing. The normalized effects of each of the factors on a response were compared and found to be more or less equal for most of the columns and to remain constant with time. The responses were most affected by the pH of the mobile phase and by the content of the organic modifier. In general it was found that C-8 columns were preferred for this assay.

Chlortetracycline↗
PubMed1989

Predictability of demographic variables in the short run.

In assessing the performance of population forecasts, it is useful to have a standard with which forecast errors can be compared. Univariate time series models may provide such a standard. Mean forecast errors of time series models indicate to what extent the movement of a variable could have been predicted from its own past. These errors show the degree of predictability that is attainable, at least in a given period. In this paper 3 time series methods (exponential smoothing, Box-Jenkins method, and structural time series models) are applied to Dutch data on births, deaths, marriages, immigrants, and emigrants. The variability of prediction errors between different periods is examined. The possibility that univariate predictions can be improved by using quarterly or monthly data instead of annual data is tested.

Demography↗
PubMed1979

EC-GLC determination of the herbicidal monohalogenated phenoxyalkyl acid mecoprop in tissues, urine and plasma after derivatization with pentafluorobenzylbromide.

An EC-GLC method for the determination of the systemic herbicide methylchlorophenoxypropionic acid (meco prop), a monohalogenated phenoxyalkyl acid, in 0.5 gram of rabbit tissues and in one ml human urine and plasma, is presented. Monohalogenated chlorophenoxyalkyl acids can reach a high sensitivity for electron-capture detection as pentafluorbenzylester derivatives; so their minimum detectable amount is about 5 pg. A test-tube micro-extraction method for MCPP fromurine, plasma and homogenized tissues with benzene, after acidification with 2 N HC1, the derivatization the residue, and the column clean-up over silicagel, are described in detail. Results of recovery studies with variation-coefficient determination are given by analysis of spiked tissues liver and brain, urine and plasma using p-chlorophenoxy-isobutyric acid (CPIB) as the internal standard. With this method other chlorophynoxyalkyl acid herbicides also can be determined in biological post-mortem material

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed1977

Toxicological analysis in a case of endosulfan suicide.

Stomach, small intestine contents, blood, liver, kidney and urine of a 28-years old man, were analyzed for residues of Endosulfan (6, 7, 8, 9, 10, 10-hexachloro-1, 5, 5a, 6, 9, 9a-hexahydro-6, 9-methano-2, 4, 3-benzo(e)dioxathiepin 3-oxide). The analysis results showed the presence of high concentrations of the two endosulfan isomers in all samples. Since also alcohol was present in all the tissues analyzed, it was concluded that the victim died of a combined endosulfan-alcohol poisoning. No other drugs were found.

Adult↗
PubMed1976

A forward view of health services in South Africa.

This article is an exposition of health services, past, present and future, in the Republic of South Africa, with particular reference to the Black homelands and their development in the fields of personal health services, nutritional services and laboratory services. It also deals with manpower resources and medical aid.

Adult↗
PubMedDate not supplied

Collaborative study of the analysis of chlortetracycline hydrochloride by liquid chromatography on polystyrene-divinylbenzene packing materials.

A previously established method for the analysis of chlortetracycline by liquid chromatography using polystyrene-divinylbenzene stationary phases was examined in a multicentre study involving four laboratories and a total of 12 columns. Three chlortetracycline hydrochloride samples were analysed. The main component and the impurities were determined. An analysis of variance, treating each column as a different laboratory, showed absence of consistent laboratory bias and presence of significant laboratory-sample interaction. Estimates for the repeatability and reproducibility of the method, expressed as relative standard deviations of the result of the determination of chlortetracycline hydrochloride, were calculated to be 0.7 and 1.2%, respectively. When the analysis of variance was performed using only the results obtained on the wide pore (1000 A) stationary phases, the laboratory-sample interaction strongly decreased. It is therefore proposed to use such materials for the analysis of chlortetracycline.

Analysis of Variance↗
PubMedDate not supplied

Suicidal poisoning by MCPA and parathion.

A suicidal poisoning committed by a sixty-five year old woman, who swallowed a bottle of Agroxyl, containing an aqueous 250 g/L solution of the sodium- and potassium salt of 2-methyl-4-chlorophenoxyacetic acid [MCPA], together with lethal amounts of a parathion formulation, is described. The case history, the postmortem examination and the concentrations of parathion and MCPA in the different viscera, are reported in detail. Parathion determination was performed by means of a routine method, previously developed in our laboratory. The MCPA quantification was achieved using a thoroughly evaluated EC- GLC micro-analytical procedure, which is discussed completely. Identity was confirmed by GC-MS. Intake of lethal parathion quantities caused the woman's death with five minutes. This case however is worth reporting, since we had the unique opportunity to establish the early distribution of MCPA through the body, during the short period of survival.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMedDate not supplied

Suicidal poisoning by nitrite.

The authors relate a suicidal poisoning by nitrites. Post mortem findings are reported as well as a method for the quantitative assessment of NO2- in blood, urine, gastric and intestinal contents, kidney and liver. The concentration values obtained are correlated with the methemoglobin figures which indeed are lethal. The highest concentrations of NO2- are found in the small intestine where the nitrites seem to resist chemical decomposition owing to the reducing properties of the bacterial flora.

Abdomen↗