Biomedical subjects

W Lo

Publications and source records attributed to W Lo.

At least 19 recordsLinked to original sources

PubMed2004

Bronchopulmonary sequestration supplied by the coronary circulation associated with a right-sided aortic arch.

Bronchopulmonary sequestration is an uncommon congenital anomaly. Although systemic arterial supply to the abnormal lung tissue is usually derived from the aorta, other nutrient vascular sources have also been described, including, infrequently, the coronary circulation. A right-sided aortic arch is another rare vascular abnormality, generally present in the setting of a vascular ring. We report a case of pulmonary sequestration receiving arterial supply from the right coronary artery, in the presence of a right-sided aortic arch, a constellation of anomalies not previously described.

Journal Article↗

PubMed2004

Pharmacokinetics of gabapentin in paediatric patients with uncontrolled seizures.

PURPOSE: The pharmacokinetics of gabapentin in paediatric patients with uncontrolled seizures was studied. METHODS: Thirteen paediatric patients (mean age: 9.4 years) with uncontrolled partial seizures were included. Patients received gabapentin orally until doses were individualized to 9.6-39.8 mg/kg/day. Blood samples were obtained just prior to the dose and over 8 h after gabapentin was administered in the fasting state. The plasma concentration of gabapentin was measured by a high-performance liquid chromatography assay. Pharmacokinetic parameters for gabapentin were determined by non-compartment methods using multivariate regression analysis. RESULTS: Data from nine patients were suitable for pharmacokinetic analysis. The C(max) from 0.9 to 5.8 microg/mL (mean: 2.6 +/- 1.7 microg/mL) and T(max) from 0.5 to 2.0 h (mean: 1.6 +/- 1.0 h). The apparent clearance (Cl/F) ranged from 0.12 to 1.12 L/h/kg (mean: 0.50 +/- 0.29 L/h/kg), and the elimination half-life from 3.2 to 12.2 h (mean: 5.5 +/- 0.8 h). Five patients experienced moderate (n = 4) to severe (n = 1) aggressive behaviour and another gained weight on gabapentin. CONCLUSIONS: Our data suggests that gabapentin pharmacokinetics can vary substantially among paediatric patients. Gabapentin was well tolerated in patients with uncontrolled partial seizures up to 6 months of therapy.

Adolescent↗

PubMed2003

Bacterial biosorbent for removing and recovering copper from electroplating effluents.

Investigations were carried out to study the removal and recovery of Cu(II) ions from wastewater by Micrococcus sp. The Langmuir isotherm model described very well the equilibrium behavior of copper biosorption, with maximum biosorption capacity (q(max)) reaching 52.1 mg Cu2+/g dry cell at pH 6. Biomass prewashed with sulfuric acid (0.05 mol 1(-1)) and sodium sulfate (1 mol l(-1)) solutions were shown to increase the copper removal capabilities up to 27% and 16%, respectively. Copper uptake by cells was negligible at pH 2.0 and then increased quickly with increasing pH until 6.0. Cells of Micrococcus sp. were immobilized in 2% calcium alginate and 10% polyacrylamide gel beads. A counter-current process comprising a series of immobilized cell reactors was developed for removing and recovering copper from electroplating effluents. This process was capable of producing an effluent at low copper concentration, with only a minimum amount of desorbing agent used. The technique of scanning electron microscopy coupled with X-ray dispersion analysis shows that Cu2+ exchanged with K+ and Ca2+ on the cell wall of Micrococcus sp., thereby suggesting ion exchange as one of the dominant mechanisms of metal biosorption for this bacterial strain.

Adsorption↗

PubMed2002

Association of ancillary services with primary care utilization and retention for patients with HIV/AIDS.

Fenway Community Health Center (FCHC), located in Boston, Massachusetts, provides comprehensive care to persons with HIV/AIDS, including medical, mental health and other health-related services. In this paper, we present results from an analysis of existing data about the demographic and clinical characteristics, service needs and utilization patterns, and primary care retention of HIV-positive primary care patients seen at FCHC during a 24-month study period. Patient data were extracted from Logician, FCHC's electronic medical record system, and imported into Microsoft Access, Microsoft Excel and SAS for manipulation and analysis. A total of 999 unique individuals were included in the study population. Most were men (97%), white (75%) and between 39 and 80 years of age. Patients averaged 6.7 medical visits annually at FCHC, and 61% had at least one medical visit every six months. Significant predictors of primary care utilization were insurance status, HIV disease stage, being on combination therapy, first CD4 count, first viral load level and receipt of ancillary services. Need and receipt of ancillary services were found through medical and case management record review; case management was the most used ancillary service, received by 36% of the study population. For most ancillary services, clients with assessed need had documented receipt of the service. Publicly insured and/or Ryan White CARE Act-funded patients had the greatest ancillary service utilization. The influence of ancillary services upon primary care entry could not be evaluated with available data; however, their influence upon primary care was significant. For patients who received primary care in every continuous six-month period, statistically significant associations were found with receipt of mental health care, case management, drug assistance, food/nutrition, complementary services and housing. Using the more rigorous FCHC standard of care (minimum of four primary care visits per year), significant associations were also found with transportation, legal services and substance abuse treatment. For non-whites and women, mental health care, food/nutrition, housing and transportation had particular significance.

Adult↗

PubMed2001

The degradation of xenobiotic branched carboxylic acids in anaerobic sediment of the Pearl River in Southern China.

Xenobiotic branched carboxylic acids (BCAs) discharged by industries are often persistent in biological wastewater treatment systems and end up in water and sediments. In this study, the degradation of 12 typical BCAs in an anaerobic environment of river sediment was studied in vitro using enrichment shake-flask cultures. The anaerobic consortium taken from the river sediment, comprising BCA-degrading and methane-producing genera, degraded BCAs with tertiary carbons through beta-oxidation, followed by methanogenesis mechanisms. The maximum cell densities in the cultures using BCAs as the sole carbon source ranged between 5.0 and 6.0 x 10(5) cells/ml. The maximum degradation rates were between 5.0 and 8.5 x 10(-3) mmol/h. The consortium could not degrade BCAs with quaternary carbons. The degree of branching at the alpha or beta position along the carbon chain interfered with the beta-oxidation mechanisms. These BCAs would accumulate in the sediment and significantly affect the cycling of organic carbon and nutrients.

Bacteria, Anaerobic↗

PubMed2001

Assessment of heavy metal cations in sediments of Shing Mun River, Hong Kong.

The extent of heavy metal cation contamination in the Shing Mun River has been assessed. Sediment samples were taken at eight strategic locations along the river system. The highest concentrations of copper (Cu, 1.66 mg/g), lead (Pb, 0.354 mg/g), zinc (Zn, 2.2 mg/g) and chromium (Cr, 0.047 mg/g) were found in the Fo Tan Nullah, a major tributary of the Shing Mun River. The highest concentrations of aluminum (114 mg/g) and cadmium (Cd, 0.047 mg/g) were found in the Shing Mun Main River Channel. These contaminated sediments, accumulated over the years on the river bed, could act as secondary sources of pollution to the overlying water column in the river.

Cations↗

PubMed2001

Nutrient release and sediment oxygen demand in a eutrophic land-locked embayment in Hong Kong.

Tolo Harbour is a large eutrophic land-locked estuarine embayment in Hong Kong. The rapid urbanization, commercio-industrial activities and lack of legislative control around the Tolo catchment produced large quantities of untreated or partially treated municipal sewage, agricultural wastes and cottage industrial effluents which were discharged into Tolo Harbour via rivers and watercourses. Control measures were implemented to reduce the external nutrient loading into the harbour since the early 1980s. Nutrient data for the period 1982 to 1997 were analyzed for temporal trends. Over the period of observation, the total inorganic nitrogen and total phosphorus both show an increasing trend, despite a decade of efforts in reducing nutrient loading. The release rates of potentially mobile nitrogen (N) and phosphorus (P) from the sediments collected from Tolo Harbour were determined by N and P release experiments under oxic conditions. The experimental results showed that the sediment released significant amount of nutrients, especially orthophosphates and ammonia nitrogen. The maximum release rates were 15.0 and 206.0 mg/m2/day, respectively. Although the external nutrient loading has been reduced, nutrients could gradually be released back into the water column from the contaminated sediments and delay improvement of the water quality.

Environmental Monitoring↗

PubMed2001

Biosorption of heavy metals by bacteria isolated from activated sludge.

Twelve aerobic bacteria from activated sludge were isolated and identified. These included both Gram-positive (e.g., Bacillus) and Gram-negative (e.g., Pseudomonas) bacteria. The biosorption capacity of these strains for three different heavy metals (copper, nickel, and lead) was determined at pH 5.0 and initial metal concentration of 100 mg/L. Among these 12 isolates, Pseudomonas pseudoalcaligenes was selected for further investigation owing to its high metal biosorption capacity. The lead and copper biosorption of this strain followed the Langmuir isotherm model quite well with maximum biosorption capacity (q(max)) reaching 271.7mg of Pb2+/g of dry cell and 46.8 mg of Cu2+/g of dry cell at pH 5.0. Study of the effect of pH on lead and copper removal indicated that the metal biosorption increased with increasing pH from 2.0 to 7.0. A mutual inhibitory effect was observed in the lead-copper system because the presence of either ion affected the sorption capacity of the other. Unequal inhibitions were observed in all the nickel binary systems. The increasing order of affinity of the three metals toward P. pseudoalcaligenes was Ni < Cu < Pb. The metal biosorptive potential of these isolates, especially P. pseudoalcaligenes, may have possible applications in the removal and recovery of metals from industrial effluents.

Adsorption↗

PubMed2001

Removal and recovery of copper (II) ions by bacterial biosorption.

Studies were conducted to investigate the removal and recovery of copper (II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process. The equilibrium of copper biosorption followed the Langmuir isotherm model very well with a maximum biosorption capacity (q(max)) of 36.5 mg of Cu2+/g of dry cell at pH 5.0 and 52.1 mg of Cu2+/g of dry cell at pH 6.0. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper. Copper uptake by cells was negligible at pH 2.0 and then increased rapidly with increasing pH until 6.0. In multimetal systems, Micrococcus sp. exhibited a preferential biosorption order: Cu approximate to Pb > Ni approximate to Zn. There is virtually no interference with copper uptake by Micrococcus sp. from solutions bearing high concentrations of Cl-, SO4(2-), and NO3- (0-500 mg/L). Sulfuric acid (0.05 M) was the most efficient desorption medium, recovering >90% of the initial copper sorbed. The copper capacity of Micrococcus sp. remained unchanged after five successive sorption and desorption cycles. Immobilization of Micrococcus sp. in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61%. Biomass of Micrococcus sp. may be applicable to the development of potentially cost-effective biosorbent for removing and recovering copper from effluents.

Adsorption↗

PubMed2001

The evolution of the Fenway Community Health model.

Fenway Community Health was founded by community activists in 1971 in the Fenway neighborhood of Boston, Mass, and within a decade had rapidly expanded its medical services for gay men in response to the AIDS epidemic. Increased expertise and cultural competence in lesbian, gay, bisexual, and transgender (LGBT) care led to expansion of medical services to address broader community concerns, ranging from substance use to parenting issues to domestic and homophobic violence, as well as specialized programs for lesbians, bisexuals, and transgendered individuals. Fenway began as a grassroots neighborhood clinic. In 1975, the center recorded 5000 patient care visits; in 2000, Fenway's clinical departments recorded 50,850 visits by 8361 individuals, including more than 1100 individuals receiving HIV-associated care. The center now has more than 170 staff people responsible for clinical programs, community education, research, administration, planning, and development. Over the past few years, Fenway's annual budget has exceeded $10 million. Fenway has established standards for improved cultural competence about LGBT health issues for other health providers and has developed programs to educate the general community about specific LGBT health concerns. This health center may provide a model of comprehensive LGBT health services that have a local impact.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Application of a luminescence-based pH optrode to monitoring of fermentation by Klebsiella pneumoniae.

The application of an optical sensor based on immobilization of the ruthenium complex [Ru(bpy)2(dhphen)]2+ (bpy = 2,2'-bipyridine, dhphen = 4,7-dihydroxy-1,10-phenanthroline) in Nafion to pH monitoring of fermentation by Klebsiella pneumoniae is described. Interference from the culture medium can be eliminated by addition of a black microporous filter membrane (pore size: 0.45 microm) on top of the sensing film. The response of this pH optrode was found to show good correlation with the conventional pH electrode.

Fermentation↗

PubMed2000

Interferon-gamma downregulates ion transport in murine small intestine cultured in vitro.

Effects of IFN-gamma on mammalian small intestinal ion transport were studied in vitro using incubated sheets of murine small intestine in Ussing chambers. In oxygenated standard culture medium containing hydrocortisone and antibiotics, they maintained their short-circuit current (I(sc)) responses to glucose and theophylline for 48 h. Histological examination revealed a 50% diminution of villus height over 36 h but no change in crypts. Height was better maintained during a 36-h incubation of small intestine from SCID mice, suggesting a role for B or T lymphocytes in villus atrophy. Exposure of small intestine to 100 U/ml IFN-gamma for 36 h decreased basal I(sc) by 40% and I(sc) responses to glucose and theophylline by approximately 70%; at 1,000 U/ml for 36 h, IFN-gamma inhibited these I(sc) responses by 90%. An inhibitor of inducible NO synthase did not reverse these effects, suggesting that they are not mediated by NO. Tissue resistance, mucosal K(+) content, and epithelial morphology were not affected. Ouabain-sensitive ATPase activity in homogenates was inhibited 60% by IFN-gamma (100 U/ml for 36 h). IFN-gamma inhibition of I(sc) responses to glucose and theophylline also occurred in SCID mouse small intestine. Thus murine small intestinal sheets can be maintained viable in vitro for at least 48 h, although villus blunting develops (but less so in SCID mouse small intestine). Also, prolonged exposure to IFN-gamma downregulates Na(+)-coupled glucose absorption, active Cl(-) secretion, and Na(+)-K(+)-ATPase activity, effects unlikely to be mediated by enhanced NO.

Animals↗

PubMed2000

Effects of trace levels of copper, chromium, and zinc ions on the performance of activated sludge.

The effects of copper, chromium, and zinc ions, at trace levels, on the performance of a simulated activated sludge process were investigated. The results of batch adsorption experiments showed that the adsorption of copper, chromium, and zinc ions followed both the Langmuir and Freundlich isotherms. The presence of trace levels of these three metals not only reduced the adsorption rate of organic matters but also the chemical oxygen demand adsorption capacity (CAC) of the activated sludge. Metal ions competed with the organic substrate for adsorption binding sites on the surfaces of activated sludge bioflocs and reduced the CAC. Studies performed in a sequential batch reactor (SBR) showed that the presence of trace levels of heavy metal ions in wastewater affected the SBR performance to different extents depending on the hydraulic retention time (HRT). When the reactors were operated at short HRTs of 2.5 d or less, the presence of trace levels of heavy metal ions reduced substantially the CAC of activated sludge, which, in turn, affected significantly the performance of the SBR. However, under longer HRTs (e.g., 5 d), the heavy metal ions in the wastewater reduced the CAC but had no significant effect on the chemical oxygen demand removal efficiency.

Adsorption↗

PubMed1999

Monitoring the toxicity of phenolic chemicals to activated sludge using a novel optical scanning respirometer.

This paper reports the development of optical scanning respirometer for determining the toxicity of chemicals to activated sludge. The respirometer is used to measure the dissolved oxygen concentration by monitoring the luminescence intensity of ruthenium dye immobilized in a polymer film in contact with the wastewater sample. The intensity is related to the extent of oxygen quenching of luminescence. The toxicity of chemicals can be evaluated by measuring the inhibition on respiration rate of microorganism using the scanning respirometer. The IC50 values (concentration of a chemical that exhibits 50% respiration inhibition) of various phenolic chemicals in activated sludge were determined. The performance of this method is compared with other toxicity methods. The experimental results indicate that the reproducibility and sensitivity of this respirometer are reasonably good.

Environmental Pollutants↗

PubMed1999

A comparative investigation on the biosorption of lead by filamentous fungal biomass.

The removal of lead from aqueous solutions by adsorption on filamentous fungal biomass was studied. Batch biosorption experiments were performed to screen a series of selected fungal strains for effective lead removal at different metal and biomass concentrations. Biosorption of the Pb2+ ions was strongly affected by pH. The fungal biomass exhibited the highest lead adsorption capacity at pH 6. Isotherms for the biosorption of lead on fungal biomass were developed and the equilibrium data fitted well to the Langmuir isotherm model. At pH 6, the maximum lead biosorption capacity of Mucor rouxii estimated with the Langmuir model was 769 mg/g dry biomass, significantly higher than that of most microorganisms. Biomass of Mucor rouxii showed specific selectivity for Pb2+ over other metals ions such as Zn2+, Ni2+ and Cu2+. This fungal strain may be applied to develop potentially cost-effective biosorbent for removing lead from effluents. The technique of scanning electron microscopy coupled with X-ray dispersion analysis shows that Pb2+ has exchanged with K+ and Ca2+ on the cell wall of Mucor rouxii, thereby suggesting ion exchange as one of the dominant mechanisms of metal biosorption for this fungal strain.

Absorption↗

PubMed1999

Persistence of human immunodeficiency virus in semen after adding indinavir to combination antiretroviral therapy.

Changes in human immunodeficiency virus (HIV) type 1 concentration and protease genotype were evaluated in semen specimens from 22 HIV-positive men before and 6 months after the addition of indinavir to dual nucleoside therapy. Seminal HIV was detected by polymerase chain reaction analysis for DNA or RNA for 59% of men before combination treatment and persisted at 6 months for 31% of the men who initially had seminal HIV detected (P = .026). The maximum levels of cell-free RNA, cell-associated RNA, and proviral DNA in semen before treatment and at 6 months were 400,000 and 10,000 copies/mL, 70,000 and 27,000 copies/mL, and 80,000 and 3,000 copies/mL, respectively. Three of the four men with persistent seminal DNA had plasma viral loads of > 10,000 copies/mL before treatment. One patient who became intolerant to indinavir had seminal HIV RNA detected by PCR analysis after 6 months. Although none of the cultures of semen specimens from the four men with PCR analysis-detectable seminal DNA after 6 months yielded HIV, indinavir resistance mutations were identified in a seminal leukocyte DNA specimen from one patient, and a second patient whose therapy was switched to saquinavir had different protease inhibitor resistance mutations in seminal and blood leukocyte DNA specimens. HIV-1 protease inhibitor resistance mutants may emerge in the semen of patients receiving combination therapy.

Anti-HIV Agents↗

PubMed1999

Neutrophils do not mediate blood-brain barrier permeability early after controlled cortical impact in rats.

Controlled cortical impact (CCI) produces blood-brain barrier (BBB) permeability and an acute inflammatory response in injured brain, associated with upregulation of cell adhesion molecules and accumulation of neutrophils. Nevertheless, the role of acute inflammation in the pathogenesis of BBB permeability after traumatic brain injury (TBI) is undefined. The purpose of this study was to examine the time course of acute inflammation and BBB permeability after CCI in rats and to determine the effect of neutrophil depletion on BBB permeability early after CCI. In the first protocol, four groups of rats (n = 4-7/group) were subjected to CCI. Expression of endothelial (E)-selectin on cerebrovascular endothelium, accumulation of neutrophils, and BBB permeability were measured in brain at 1, 4, 8, and 24 hours after injury by immunohistochemistry or spectrophotometric quantification of Evans blue. E-selectin upregulation and neutrophil accumulation in injured brain occurred at later times than maximal BBB permeability. In a second protocol, rats made neutropenic with a murine monoclonal IgM antibody (RP-3) specific for rat neutrophils were subjected to CCI, given Evans blue at 3.5 hours, and sacrificed at 4 hours after injury. Neutrophil depletion did not affect BBB permeability at 4 hours after CCI. We conclude that events other than those mediated by neutrophils initiate BBB permeability early after CCI.

Animals↗

PubMed1999

Gene transfer into the CNS using recombinant adeno-associated virus: analysis of vector DNA forms resulting in sustained expression.

Recombinant adeno-associated virus (rAAV) vectors have shown significant promise as vehicles for in vivo gene transfer, particularly for transduction of organs composed primarily of non-dividing cells (i.e., muscle, CNS, and liver). However, the mechanistic basis for this desirable property remains unclear. To investigate the fate of rAAV genomes in mouse brain, we stereotactically injected an rAAV vector carrying the E. coli lacZ gene into the caudate of BALB/c mice and demonstrate efficient transduction of mouse brain cells that possess cellular morphology consistent with post-mitotic neurons. We observed a significant increase in beta-galactosidase expression from 5 to 56 days after injection that paralleled the disappearance of single-stranded DNA input genomes. Analysis of in vivo viral DNA forms over time out to 5 months after inoculation revealed that rAAV genomes associated with high molecular weight mouse chromosomal DNA by 14 days after injection and persisted for the length of this study. The pattern of Southern hybridization was consistent with random viral integration in predominantly head-to-tail concatameric arrays. Importantly, we also documented an additional DNA species that appears to be a monomeric episomal circular form based on nuclease sensitivity assays. These data are the first to document the existence of multiple vector DNA forms present within the adult murine brain following direct rAAV inoculation and therefore, provide insight into the molecular events that ultimately result in long-term rAAV mediated transgene expression.

Animals↗