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Biomedical subjects

P A Cooper

Publications and source records attributed to P A Cooper.

At least 19 recordsLinked to original sources
PubMed2002

Rapid-extraction oxidation process to recover and reuse copper chromium and arsenic from industrial wood preservative sludge.

Chromated copper arsenate (CCA) wood preservative can form insoluble sludges when the hexavalent chromium component is reduced by wood extractives, wood particles and preservative additives in the solution. This sludge accumulates in treating solution work tanks, sumps and in-line filters and must be disposed of as hazardous wastes by waste disposal companies at high costs. A number of commercial sludges were investigated and found to contain 18-94% copper, chromium and arsenic as oxides combined with sand, oil, wood particles, additives and wood extractives. We have developed a multi-stage recycling process whereby approximately 97% of the CCA components are recovered from the sludge. It involves extraction with sodium hypochlorite to remove and oxidize chromium (more than 90%) and extract most of the arsenic (approx. 80%) followed by extraction of the copper and remaining arsenic and chromium with phosphoric acid. The phosphoric acid extract contains some trivalent chromium, which is subsequently oxidized by sodium hypochlorite. The combined oxidized extract containing CrVI, CuII and AsV was compatible with CCA treating solutions and could be re-used commercially for treating wood without having a significant effect on the preservative fixation rate or the leach resistance of the treated wood. A cost analysis showed that the economic savings from recovery of CCA chemicals and reduced landfill costs exceeded the variable costs for materials and energy for the process by as much as Can $966 per tonne of sludge if sodium sulfite can be acquired in bulk quantities for the process.

Arsenates↗
PubMed2002

Hematological reference ranges in black very low birth weight infants.

This study compared hematological reference ranges in black very low birth weight infants to previously published values established predominantly on white subjects. Ninety-four healthy, black, premature babies with a birth weight of 800 to 1500 g at 2-7 days of age were enrolled as part of a study comparing blood transfusions and high- versus low-dose recombinant erythropoietin in anaemia of prematurity. Peripheral venous blood was collected for a full blood count and differential, fetal hemoglobin and erythropoietin levels. The hematological parameters observed in black very low birth weight neonates are similar to previously published reference ranges, except that lower limits of normal were observed for hemoglobin and the red cell indices.

Black or African American↗
PubMed2002

A comparison of high versus low dose recombinant human erythropoietin versus blood transfusion in the management of anaemia of prematurity in a developing country.

The purpose of this study was to evaluate the effectiveness of early treatment with erythropoietin (EPO) in two different treatment regimes (high vs. low dose) in comparison to the conventional treatment of packed red blood cell (PRBC) transfusions in the management of anaemia of prematurity in a country with limited resources. An open controlled trial was conducted on 93 preterm infants (7 days postnatal age, 900-1500 g birthweight). Patients were randomly assigned either to a low dose (250 IU/kg), a high dose (400 IU/kg), or a control group. EPO was administered subcutaneously three times a week and all infants received 6 mg/kg iron orally from study entry to endpoint of therapy. Haematological parameters were measured and compared. The success was defined as an absence of transfusions and a haematocrit that did not fall below 30 per cent during the time period that the infants were in the study. The three groups were statistically comparable at study entry with respect to gestational age, birthweight, Apgar scores, and haematological values. Over the period that the infants were in the study, 75 per cent of the low dose group and 71 per cent of the high dose group met the criteria for success compared with 40 per cent in the control group (p < 0.001). However, there was no significant difference in the number of transfusions when the low and high EPO dose groups (9.5 per cent) were combined and compared with the control group (26.7 per cent) p = 0.0587. It was concluded that in stable infants, 900-1500 g, where phlebotomy losses are minimized and stringent transfusion guidelines are adhered to, EPO does not significantly decrease the number of transfusions. A conservative approach in the management of anaemia of prematurity, is a viable alternative in areas with limited resources.

Anemia, Neonatal↗
PubMed2001

Is prophylaxis of early-onset group B streptococcal disease appropriate for South Africa?

BACKGROUND: Early-onset group B streptococcal (GBS) disease in neonates can be prevented by the use of intrapartum chemoprophylaxis. There are two prevention strategies, one based on risk factors and the other on culture screening for GBS. This study sought to establish whether GBS chemoprophylaxis is appropriate in a developing country such as South Africa. METHODS: All neonates with early-onset GBS disease born at Johannesburg Hospital between 1 January 1995 and 21 December 1997 were reviewed. Data were collected prospectively between 1 January and 31 October 1998. Data included demographic information, obstetric information, disease characteristics, admission details and mortality. The approximate cost of implementing both strategies was determined. RESULTS: The overall incidence of early-onset GBS was 1.16 per 1,000 live births. The rate was significantly greater in 1998 compared with the previous years. Most of the babies were born preterm (70%), and 60% required admission to the neonatal intensive care unit (ICU) (a total of 81 ICU days). Twelve of the babies died. Assuming that chemoprophylaxis would reduce the number of ICU days by half, this would save an amount of R52,000. Culture-based chemoprophylaxis would cost R10 million, whereas an approach based on risk factors would cost R31,140. CONCLUSION: In conclusion, we feel that early-onset GBS disease is sufficiently prevalent in our unit to justify the implementation of a chemoprophylaxis strategy based on risk factors. Whether other units should adopt a similar approach would depend on the local incidence of early-onset GBS.

Developing Countries↗
PubMed2000

Capillary electrochromatography for pesticide analysis: effects of environmental matrices.

An insecticide, pirimicarb, and a fungicide, azoxystrobin, were analyzed by capillary electrochromatography. Nine environmental matrices derived from soil, plant and animal extracts were used. After a series of 311 consecutive injections with no washing between injections, retention times increased by ca. 0.5 min. The use of exaggerated application rates for metabolism studies enabled the detection of xenobiotic pesticide degradates by UV absorbance. A 1.2 mm path length, high-sensitivity flow cell gave a gain in sensitivity; however, a further increase in sensitivity of at least two orders of magnitude is required for pesticide residue analysis. Analyte stacking using large volume injections of aqueous samples led to a large increase in retention times.

Acrylates↗
PubMed2000

Synthesis and antitumour activity of new derivatives of flavone-8-acetic acid (FAA). Part 4: Variation of the basic structure.

A range of 11 derivatives of flavone-8-acetic acid (FAA) in which the structure has been substantially altered in different ways have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. The generally poor activity observed shows that the basic structure cannot be altered much without destroying the activity.

Animals↗
PubMed2000

Serial interleukin 6 measurements in the early diagnosis of neonatal sepsis.

The objective of the present study was to evaluate serial interleukin 6 (IL6) levels in the early diagnosis of neonatal sepsis. Subjects included 255 neonates from the Neonatal Unit of Johannesburg Hospital evaluated for suspected sepsis between February and May 1998. All infants had IL6, full blood count (FBC), C reactive protein (CRP) and blood cultures done at presentation. CRP and IL6 were repeated after 24 h. Infants were categorized into groups according to the likelihood of infection on the basis of clinical presentation, CRP, FBC and culture results, i.e., group 1 (no infection) to group 4 (definite infection). IL6 was compared between the groups by the U-test of Mann-Whitney; stepwise logistic regression was done to establish the best predictors of infection, sensitivity, specificity, positive and negative predictive values were determined. The initial IL6 level was significantly raised in those infants with possible infection [880.67 pg/ml (2966.04), p value 0.0104], probable infection [422.62pg/ml (4077.7), p value 0.0021] and definite infection [11164.39pg/ml (24139.77), p value 0.0000] as compared to those infants without infection [58.65 (182.4)]. The best predictors of infection were the combination of the initial IL6 value and CRP value after 24 h (goodness of fit 97.7 per cent). An initial IL6 value below 20 pg/ml gave a negative predictive value of 90.18 per cent. It is concluded that an IL6 value done at the time of presentation of signs and symptoms suggestive of infection is useful in the early diagnosis of neonatal sepsis. In particular, an initial IL6 value below 20 pg/ml may allow antibiotics to be withheld in a number of infants evaluated for sepsis. There is no benefit in serial determination of IL6 in the diagnosis of neonatal sepsis.

Biomarkers↗
PubMed2000

Use of C-reactive protein to guide duration of empiric antibiotic therapy in suspected early neonatal sepsis.

BACKGROUND: Serial C-reactive protein (CRP) measurements have been shown to be useful for guiding duration of antibiotic therapy in neonates. This study sought to determine whether this is a safe and practical approach in a developing country. METHODS: The study was conducted at the Johannesburg Hospital between September 15, 1998, and January 15, 1999. Subjects included all neonates evaluated for suspected sepsis in the first 24 h of life who had negative initial and repeat CRP values (< or = 10 mg/l) [corrected]. Repeat CRP measurements were performed between 24 and 48 h after birth. Antibiotic therapy was stopped in these infants at 24 to 48 h, and they were observed until 72 h, when the final blood culture results were available. The number of positive blood cultures in this group was determined. RESULTS: The repeat CRP estimation correctly identified 99 of 100 infants in the study as not requiring further antibiotic therapy (negative predictive value, 99%; 95% confidence intervals, 95.6 to 99.97%). The 1 infant with a positive blood culture was premature with a gestational age of 31 weeks. Eight babies required repeat evaluation for suspected sepsis, 4 presented on Day 3 to 4 and one of these babies died. All these neonates were of < or =33 weeks gestation. CONCLUSION: The use of serial CRP measurements to guide antibiotic therapy is a safe and practical approach in neonates with suspected sepsis in a developing country.

Anti-Bacterial Agents↗
PubMed2000

HIV-1 co-infection in children hospitalised with tuberculosis in South Africa.

SETTING: Hospitals associated with the Department of Paediatrics at the University of the Witwatersrand, Johannesburg, South Africa. OBJECTIVES: To define the prevalence of human immunodeficiency virus (HIV) co-infection and differences in clinical presentation between HIV-infected and non-infected hospitalised children with tuberculosis. DESIGN: Children were prospectively enrolled between August 1996 and January 1997. RESULTS: Of 161 children enrolled, 42% were HIV-infected, including 67/137 with pulmonary tuberculosis (PTB) and 1/24 with extra-pulmonary disease (EPTB). Positive microscopy or bacteriology did not differ by HIV status for children with either PTB or EPTB. Although age did not differ between HIV-infected and non-infected children with PTB, non-HIV-infected children with EPTB were significantly older than those with PTB only (median age 32 months vs 14.5 months, P = 0.004). Chronic weight loss, malnutrition and the absence of BCG scarring were more common in HIV-infected children with PTB. HIV-infected children were also more likely to show cavitation (P = 0.001) and miliary TB (P = 0.01) on chest X-ray. Reactivity to tuberculin (> or = 5 mm and > or = 10 mm in HIV-infected and non-infected children, respectively) was significantly lower in HIV-infected children, as were CD4+ lymphocyte levels. The mortality rate during the study was 13.4% in HIV-infected children compared with 1.5% in non-HIV-infected children (P = 0.03). CONCLUSIONS: There is a high prevalence of HIV co-infection in children with TB. Progressive PTB and death are more common in HIV-infected children. Tuberculin skin testing is of limited use in screening for TB in HIV-infected children even when using a cut-point of > or = 5 mm.

AIDS-Related Opportunistic Infections↗
PubMed2000

AZT blues.

Explore the source record for details and available documents.

Anti-HIV Agents↗
PubMed1999

Comparison of capillary electrochromatography with high-performance liquid chromatography for the analysis of pirimicarb and related compounds.

The applicability of capillary electrochromatography (CEC) to the analysis of pirimicarb and structurally related pyrimidines has been investigated. Methods were developed to improve the separation of closely related compounds. Resolution was achieved both by the use of running buffers containing a mixture of two organic modifiers to increase selectivity and reduce retention times. Solvent composition step gradients were used to separate compounds of widely differing retention factors. A comparison has been made between HPLC and CEC using identical separation parameters and the same stationary phase, from which two important conclusions are drawn. First, it has been shown that values of k' for the compounds analyzed were the same in both techniques. Secondly, although it is evident that CEC produces higher efficiencies than HPLC when running buffers with high organic solvent content are used, as the aqueous content of the running buffer is increased the efficiencies achieved in CEC and HPLC converge until they become equivalent. This is contrary to the theoretical model which predicts efficiencies are inherently higher using electrically rather than pressure driven flow. Disadvantages of the limited control of flow-rate in CEC in comparison with HPLC, are shown.

Carbamates↗
PubMed1999

Chemokines induce the cellular migration of MCF-7 human breast carcinoma cells: subpopulations of tumour cells display positive and negative chemotaxis and differential in vivo growth potentials.

We previously reported that chemotactic cytokines (chemokines) induce the directional migration of cells derived from the breast carcinoma cell line MCF-7 in vitro, however it was apparent that only a small percentage of cells displayed the ability to migrate upon stimulation. In the present study three sub-lines derived from the parental MCF-7 cell line were selected for their ability to migrate in response to MIP-1alpha, MIP-1beta or RANTES across Transwell filters of 8 microm pore size. The first round selection of migratory cells resulted in sub-populations which demonstrated an increased chemotactic response compared with parental cells. Cells migrating to MIP-1beta were subjected to four further rounds of positive or negative selection, resulting in two sub-lines, MCF-7L4 and MCF-7U4 which displayed an increased and decreased chemotactic response respectively to MIP-1alpha MIP-1beta and RANTES. No difference in chemokine receptor RNA message expression between these sub-lines and the parental MCF-7 line were detected, although increased levels of alpha3, alpha6 and alphav integrin sub-units were shown for MCF-7L4 (positively selected sub-line) compared with MCF-7U4 cells. Moreover, the in vivo growth of cells derived from the two MCF-7 sub-lines was inversely correlated with their chemotactic response. The results of this study depict further the inherent heterogeneity in cancer, suggesting that the chemotactic response may influence the migratory traits of sub-populations within the tumour and potentially contribute to their in vivo behavior, growth and survival.

Breast Neoplasms↗
PubMed1999

Survival of low-birth-weight infants at Baragwanath Hospital--1950-1996.

OBJECTIVES: To examine changes in survival rates among low-birth-weight (LBW) infants between the years 1950 and 1996. METHODS: Survival figures were analysed for LBW infants managed at Baragwanath Hospital, a tertiary care centre in Soweto, Johannesburg, over four periods spanning five decades. RESULTS: The overall mortality rates of LBW infants decreased markedly between the early 1950s and the period 1995/96. By the mid-1990's approximately four times the number of infants with birth weight less than 1,500 g were surviving compared with the early 1950s. The reduction in mortality rates occurred in all LBW groups during the first three decades. However, since 1981 infants who weighed less than 1,500 g at birth were the major contributors to the overall reduction in mortality. Between the years 1981/82 and 1995/96, survival increased significantly from 64% to 79% for infants with birth weight 1,000-1,499 g, and from 14% to 32% for those with birth weight less than 1,000 g. Since infants in the latter group were seldom offered mechanical ventilation or artificial surfactant, a large part of these increases in survival can be attributed to improvement in the general level of care. CONCLUSION: There have been dramatic improvements in the survival of LBW infants over this time period at Baragwanath Hospital. Although newer interventions such as mechanical ventilation and artificial surfactant have played a significant role, improvement in care at primary and secondary levels has been of major importance.

Hospitals, Urban↗
PubMed1998

Angiogenesis in the hollow fiber tumor model influences drug delivery to tumor cells: implications for anticancer drug screening programs.

The National Cancer Institute uses the hollow fiber assay as part of its screening program for anticancer drug discovery. Angiogenesis to hollow fibers implanted s.c. has not been reported, thereby raising concerns about the efficiency of drug delivery and its subsequent effects on chemosensitivity. By extending postimplantation times beyond the 6-day period presently used, extensive vascular networks develop, resulting in both increased delivery and chemosensitivity to doxorubicin. This study suggests that present protocols used to evaluate compounds may produce false negative results, and additional studies to determine the predictive value of the assay are required.

Adenocarcinoma↗