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Biomedical subjects

S Ong

Publications and source records attributed to S Ong.

At least 37 records · Page 2Linked to original sources
PubMed1999

Recycling of lead-contaminated EDTA wastewater.

Ethylene diaminetetraacetic acid (EDTA) is one of the chelating agents used in the soil washing process for the decontamination of lead-contaminated soil. Lead-EDTA complexes in the wastewater from the soil washing process must be removed before the wastewater can be safely discharged. This study outlines a method to recycle Pb-EDTA wastewater by substituting the Pb complexed with EDTA with Fe(III) ions at low pH, followed by precipitation of Pb ions with phosphate or sulfate ions. Fe(III) ions complexed with EDTA were then precipitated at high pH using sodium hydroxide. The resulting solution (Fe-precipitated solution) was tested on three lead-contaminated soils. The Fe-precipitated EDTA solution was found to have similar extraction capabilities as fresh EDTA solution. Experimental results showed that the recycled EDTA solution may be recycled several times without losing its extractive power. Recycled EDTA wastewater with phosphate precipitation was found to be slightly more effective than recycled EDTA solution using sulfate precipitation. The recycling procedure may be applied to wastewater generated during soil washing of lead-contaminated soil, resulting in a reduction in wastewater generated and savings in the amount of EDTA used.

Chelating Agents↗
PubMed1999

Acetaminophen alters estrogenic responses in vitro: inhibition of estrogen-dependent vitellogenin production in trout liver cells.

The purpose of this study was to determine if acetaminophen altered estrogen-dependent vitellogenin production in isolated trout liver cells. Estrogen-induced vitellogenesis was studied in liver cells isolated from male trout and cultured in defined medium; vitellogenin secreted into culture medium was quantitated using immunological procedures. Vitellogenin production was absolutely dependent on the addition of estradiol (10(-6) M) to liver cells from male trout. Acetaminophen produced a dose-dependent inhibition of vitellogenin production; approximately 50% inhibition was achieved with 0.05 mM acetaminophen, while 0.3 mM acetaminophen inhibited secreted vitellogenin to undetectable levels. In contrast, these concentrations of acetaminophen (< or = 1 mM) did not significantly alter the production of secreted albumin, determined immunologically, or cause detectable toxicity. Higher doses of acetaminophen were toxic, but did not induce DNA fragmentation in the trout liver cells. Acetaminophen reduction of estradiol-induced vitellogenin production was accompanied by a dose-dependent decrease in vitellogenin mRNA, indicating acetaminophen inhibited a step prior to, or during, formation of vitellogenin mRNA. Estrogen receptor-binding assays demonstrated that acetaminophen did not reduce binding of [3H]-estradiol to trout liver estrogen receptor. In addition, catabolism of estradiol to water-soluble metabolites was not significantly altered by acetaminophen. These studies indicate that non-toxic concentrations of acetaminophen specifically inhibit estrogen-dependent vitellogenin synthesis and suggest that this commonly used drug may alter estrogen-regulated processes.

Acetaminophen↗
PubMed1999

Estimation of fetal weight in twins: a new mathematical model.

OBJECTIVES: Evaluation of new mathematical formula (Femur 4) derived from a twin population to estimate fetal weight in twins using ultrasound. Comparison of Femur 4 is with conventional mathematical models. DESIGN: Retrospective analysis of ultrasonic measurements of 297 twin babies from 24 to 40 weeks of gestation who were born within 10 days of ultrasound examination. SETTING: Aberdeen Maternity Hospital. METHODS: With ultrasonic measurements obtained from twin babies, estimated fetal weight was calculated using the mathematical models of Campbell, Shepard and Hadlock. The calculations were repeated for the model of Femur 4. All models were compared against Femur 4. RESULTS: The coefficient of determination of the linear regression between the actual and predicted weight was highest for Femur 4 (0.852). Femur 4 had the highest proportion of babies with estimated weights within 10% of actual birthweight (71.4%). In babies who weighed between 2000 and 3000 g, Femur 4 had the least systematic and random error of -1.69 and 8.96, respectively. For babies below the 10th centile for weight, Femur 4 had comparable positive and negative predictive values of 76.0% and 92.3%, respectively. Femur 4 was equally poor at predicting growth discordancy with positive and negative predictive values of 70.0% and 86.5% only. CONCLUSION: Femur 4 requires measurements of femur length and abdominal circumference only, hence avoiding the need to obtain difficult head measurements which is a common problem in twins. It is a good model for estimation of fetal weight in twins. However, prediction of growth discordancy remains problematic.

Body Weight↗
PubMed1999

Characterization and observation of animals responsible for rabies post-exposure treatment in Phnom Penh, Cambodia.

In order to provide relevant therapeutic answers to human patients exposed to risk of rabies infection who visit the Institut Pasteur du Cambodge for post-exposure treatment and to improve control of rabies in Cambodia, a pilot study was carried out in Phnom Penh Province in November and December 1997 with three objectives: characterization of the population of animals responsible for the exposure to rabies, observation of the animals concerned, and confirmation of the presence of rabies virus in the province. Between 18 November 1997 and 19 December 1997, 409 of the 741 patients treated at the Institut Pasteur du Cambodge because of an exposure to a known rabies vector were included in the study. The animals concerned were: 401 dogs (98%), six monkeys (1.5%) and two cats (0.5%). Three-hundred-and-seventy of the animals (90.5%) were owned, 4 (1%) were unowned but were available for characterization and observation, and 35 (8.6%) had an unknown ownership status and were not available for further study. The exposures occurred on private property in 84% of the cases, and 80 of the 370 owned animals (22%) lived in the same home as had the patient. The 374 animals with known ownership status were examined. Five were already dead and two of these five dogs had presented clinical signs typical of those of rabies. The male:female sex ratio of the dogs was 2.1:1. The 369 live animals were placed under observation for 10 d immediately after exposure of the humans had taken place. At the end of the period none of the animals had developed clinical signs of rabies, three had died of diseases other than rabies, and one was lost. Tests for the rabies nucleocapsid antigen were positive in two cases (the two suspected rabid dogs), confirming the presence of rabies in Phnom Penh Province. Consequently, we recommend measures to improve the control of rabies in Cambodia.

Animals↗
PubMed1999

Increasing incidence of ectopic pregnancy: is it iatrogenic?

The incidence of ectopic pregnancy at the National Maternity hospital in 1996 was double that of the previous year. The rise in incidence coincided with the introduction at the hospital of both serum quantitative bHCG (beta human chorionic gonadotrophin) testing and a clear protocol for the early diagnosis of ectopic pregnancy. The aim of this study was to determine whether the increased incidence in 1996 was due to an increase in pre-existing risk factors for the development of ectopic pregnancy or to increased diagnosis of the condition. For the years 1986, 1995 and 1996, the incidence of ectopic pregnancy at the National Maternity Hospital was 1.8, 4.8 and 8.3 respectively per thousand pregnancies. There was no significant difference between the three years in terms of maternal age, parity or risks factors for ectopic pregnancy. The median gestational age at diagnosis decreased from 8 weeks gestation in 1995 to 6 weeks in 1996 (p < 0.001). However, the incidence of ruptured ectopic and blood transfusion was similar in both years. This study suggests that the two-fold increase noted in the incidence of ectopic pregnancy is related to earlier diagnosis of the condition. This is aided by the availability of serum quantitative bHCG testing. These findings have important implications for the management of women with ectopic pregnancy.

Adult↗
PubMed1998

EMERGEncy ID NET: an emergency department-based emerging infections sentinel network. The EMERGEncy ID NET Study Group.

Acute infectious disease presentations among many at-risk patient groups (eg, uninsured, homeless, and recent immigrants) are frequently seen in emergency departments. Therefore EDs may be useful sentinel sites for infectious disease surveillance. This article describes the background, development, and implementation of EMERGE ncy ID NET, an interdisciplinary, multicenter, ED-based network for research of emerging infectious diseases. EMERGE ncy ID NET was established in cooperation with the National Center for Infectious Diseases, Centers for Disease Control and Prevention (CDC) as part of the CDC's strategy to expand and complement existing disease detection and control activities. The network is based at 11 university-affiliated, urban hospital EDs with a combined annual patient visit census of more than 900,000. Data are collected during ED evaluation of patients with specific clinical syndromes, and are electronically stored, transferred, and analyzed at a central receiving site. Current projects include investigation of bloody diarrhea and the prevalence of Shiga toxin-producing Escherichia coli, animal exposures and rabies postexposure prophylaxis practices, seizures and prevalence of neurocysticercosis, nosocomial ED Mycobacterium tuberculosis transmission, and hospital isolation bed use for adults admitted for pneumonia or suspected tuberculosis. EMERGE ncy ID NET also was developed to be a mechanism for rapidly responding to new diseases or epidemics. Future plans include study of antimicrobial use, meningitis, and encephalitis, and consideration of other public health concerns such as injury and national and international network expansion.

Acute Disease↗
PubMed1998

Labour ward activity and the lunar cycle.

To refute the commonly held belief by the general public that the lunar cycle affects labour, we studied 10 027 deliveries over an 18-month period in a large maternity unit in Ireland. There was no increase in the total number of deliveries during the times of a full moon compared with other times. The caesarean section, instrumental vaginal delivery, and pre-term delivery rate remained unchanged over the times of a full moon. We conclude that the lunar cycle has no influence on labour ward activity.

Journal Article↗
PubMed1997

Selective hyperexpression of c-jun oncoprotein by glass fiber- and silica-transformed BALB/c-3T3 cells.

Mining and mineral processing are important industries in the United States. A large number of workers are potentially exposed to silica during mining and to glass fibers during manufacturing. There is a concern regarding lung cancer risk among workers exposed to silica and glass fibers. Our previous studies showed that both glass fibers and silica induced transformation of BALB/c-3T3 cells. In order to explore the relationship between silica and glass fiber-induced cell transformation and oncoprotein expression, the protein products of seven proto-oncogenes (c-K-ras, c-H-ras, c-sis, c-myc, c-myb, c-erb B1 and c-jun) and one tumor suppressor gene (p53) were examined in BALB/c-3T3 cells transformed by glass fibers or silica using immunoblotting with specific monoclonal or polyclonal antibodies. The results showed that all transformants, including eight induced by glass fibers and eight by silica (Min-U-Sil 5), were positive for c-jun protein expression; the level of c-jun protein was elevated 8-21-fold in these transformants. Other protooncogene proteins in transformed cells were either not detectable or not different from non-transformed cells. These results suggest that the overexpression of c-jun is common in BALB/c-3T3 transformed cells induced by glass fibers or silica. It seems, therefore, that the expression of c-jun may play an important role in the transformation process.

3T3 Cells↗
PubMed1996

Immobilized-artificial-membrane chromatography: measurements of membrane partition coefficient and predicting drug membrane permeability.

Immobilized artificial membranes (IAMs) are chromatographic surfaces prepared by covalently immobilizing cell membrane phospholipids to solid surfaces at monolayer densities. IAM surfaces mimic fluid cell membranes. For 23 structurally unrelated compounds, solute capacity factors [log (k'IAM)] measured on IAM columns correlate very well with the solute equilibrium partition coefficients [log (Km)] measured in fluid liposome systems (r = 0.907). This indicates that solute partitioning between the IAM bonded phase and the aqueous mobile phase is similar to the solute partitioning between liposomes and the aqueous phase. IAMs also predicted oral drug absorption in mice and drug permeability through Caco-2 cells. IAM chromatography is experimentally simple and large volume screening of experimental compounds for drug absorption is possible. Solute retention on IAMs was found to be dominated by a partitioning mechanism. The structural requirements for HPLC bonded phases to predict solute-membrane partitioning are briefly discussed.

Adsorption↗