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Biomedical subjects

W Lambert

Publications and source records attributed to W Lambert.

At least 19 recordsLinked to original sources
PubMed2006

Identification of chlamydia and gonorrhoea among women in rural Haiti: maximising access to treatment in a resource poor setting.

OBJECTIVE: To develop a risk assessment algorithm that will increase the identification and treatment of women with cervical infection in rural Haiti. METHODS: Study participants were randomly selected from new patients who accessed services at a women's health clinic in rural Haiti between June 1999 and December 2002. This case-control study included women who tested positive for chlamydia and/or gonorrhoea based on the Gen-Probe PACE 2 laboratory test as cases. Controls were women who tested negative for both of these infections. RESULTS: Women from this area of rural Haiti had a limited level of education and lived in impoverished housing conditions. The sensitivity estimates of Haitian Ministry of Health and WHO algorithms for detecting chlamydia and/or gonorrhoea were generally low (ranging from 16.1% to 68.1%) in this population. Risk scores based on logistic regression models of local risk factors for chlamydia and gonorrhoea were developed and sensitivity estimates were higher for algorithms based on these risk scores (up to 98.8%); however, specificity was compromised. CONCLUSIONS: A risk assessment algorithm to identify women with chlamydia and/or gonorrhoea is more sensitive and less specific than the syndromic management approach advocated by WHO and adapted by the Haitian Ministry of Health. Using a risk assessment tool with high sensitivity based on local risk factors of cervical infection will maximise access to care, improve outcomes, and decrease morbidity in women who have cervical infection in rural Haiti.

Adult↗
PubMed2005

Factors associated with forced sex among women accessing health services in rural Haiti: implications for the prevention of HIV infection and other sexually transmitted diseases.

The goals of the current study were to: (1) estimate the prevalence of forced sex among women accessing services at a women's health clinic in rural Haiti; and (2) examine factors associated with forced sex in this population. Based on data from a case-control study of risk factors for sexually transmitted diseases (STDs), a cross-sectional analysis to examine factors associated with forced sex was performed. A number of factors related to gender inequality/socioeconomic vulnerability placed women in rural Haiti at higher risk of forced sex. The strongest factors associated with forced sex in multivariate analyses were: age, length of time in a relationship, occupation of the woman's partner, STD-related symptoms, and factors demonstrating economic vulnerability. The findings suggest that prevention efforts must go beyond provision of information and education to the pursuit of broader initiatives at both local and national levels. At the community level, policy-makers should consider advancing economic opportunities for women who are vulnerable to forced sex. Improving access to community-based income-generating activities may begin to address this problem. However, the viability of these local projects depends largely upon Haiti's 'macro-economic' situation. In order to ensure the success of local initiatives, external humanitarian and development assistance to Haiti should be supported. By broadening the definition of "prevention" interventions, we may begin to address the systemic problems that contribute to the occurrence of forced sex and the increasing incidence of HIV infection throughout the world, such as gender inequality and economic vulnerability. Taking into account factors influencing risk at the local level as well as the macro-level will potentially improve our capacity to reduce the risk of forced sex and the spread of STDs, including HIV infection, for millions of women living in poverty worldwide.

Adult↗
PubMed2003

Longitudinal study on the prevalence of benzodiazepine (mis)use in a prison: importance of the analytical strategy.

AIMS: This study evaluates the suitability of gas chromatographic-mass spectrometric (GC-MS) analysis to follow-up the extent of benzodiazepine (mis)use in a Belgian prison population and compares it to other analytical strategies (e.g. screening followed by confirmation of the positive samples). DESIGN AND PARTICIPANTS: From February to August 1998, 598 persons were jailed of which 188 (31.4% of the incoming detainees) volunteered to be screened. Urine samples (530 in total) were collected on the day of arrival and after 14, 30 and 90 days of imprisonment. MEASUREMENTS: All samples were screened by EMIT(R) for benzodiazepines and analysed subsequently by GC-MS. FINDINGS: EMIT(R) screening yielded 117 (22.1%) positive samples, a number which increased to 174 (32.8%) after GC-MS analysis. Of these 174 GC-MS positive samples, 119 (68.4%) contained one benzodiazepine while for the remaining samples multiple benzodiazepine (mis)use could be demonstrated. A significant increase in benzodiazepine (mis)use was indicated only from day 0 to day 14 based on the GC-MS results but not on the immunoassay results, even when the latter were complemented with GC-MS analysis of the positively screened samples. The GC-MS data also demonstrated that benzodiazepines are mainly (mis)used by subjects on benzodiazepine prescription as almost 50% of these subjects took additional non-prescribed benzodiazepines. During GC-MS analysis other drugs were co-extracted unintentionally and chromatographed and 23.9% of the volunteers were positive for illegal drugs on the day of arrival. CONCLUSION: Immunoassay results yield an underestimation of the problem of benzodiazepine (mis)use in prison due to the high false negative rate. GC-MS analysis of all samples therefore is the recommended strategy for this type of longitudinal study as it yields more correct and detailed information than the immunoassay results.

Belgium↗
PubMed2003

Prevalence and risk factors of STDs in rural Haiti: implications for policy and programming in resource-poor settings.

The goals of the current study are to: (1) estimate the prevalence of sexually transmitted diseases (STDs) among women accessing services at a women's health clinic in rural Haiti; and (2) identify risk factors for STDs in this setting. The design is a case control study, comparing risk factors for women who demonstrated positive laboratory results for chlamydia and/or gonorrhoea to women who tested negative for both of these pathogens. The strongest risk factors for chlamydia and/or gonorrhoea were largely economic variables, with work as a domestic servant increasing the risk by four-fold. Working as a market vendor reduced a woman's risk of having an STD by approximately 45%. Given that economic factors are strongly associated with STD risk in this context, one potential mechanism for reducing the risk of STDs, including HIV, would involve increasing economic opportunities for women in rural Haiti.

Adolescent↗
PubMed2001

Simultaneous determination of fifteen low-dosed benzodiazepines in human urine by solid-phase extraction and gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric method was developed for the simultaneous analysis of 15 low-dosed benzodiazepines, both parent compounds and their corresponding metabolites, in human urine. The target compounds are alprazolam, alpha-hydroxyalprazolam, 4-hydroxyalprazolam, flunitrazepam, 7-aminoflunitrazepam, desmethylflunitrazepam, flurazepam, hydroxyethylflurazepam, nitrogen-desalkylflurazepam, ketazolam, oxazepam, lormetazepam, lorazepam, triazolam and alpha-hydroxytriazolam. Nitrogen-methylclonazepam is used as the internal standard. The urine sample preparation involves enzymatic hydrolysis of the conjugated metabolites with Helix pomatia beta-glucuronidase for 1 h at 56 degrees C followed by solid-phase extraction on a phenyl-type column. The extracted benzodiazepines are subsequently analyzed on a polydimethylsiloxane column using on-column injection to enhance sensitivity. The extraction efficiency exceeded 80% for all compounds except for oxazepam, lorazepam and 4-hydroxyalprazolam which had recoveries of about 60%. The LODs ranged from 13 to 30 ng/ml in the scan mode and from 1.0 to 1.7 ng/ml in the selected ion monitoring (SIM) mode. Linear calibration curves were obtained in the concentration ranges from 50 to 1000 ng/ml in the scan mode and from 5 to 100 ng/ml in the SIM mode. The within-day and day-to-day relative standard deviations at three different concentrations never exceeded 15%.

Benzodiazepines↗
PubMed2001

Stir bar sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry applied to the analysis of polychlorinated biphenyls in human sperm.

Stir bar sorptive extraction (SBSE) on polydimethylsiloxane (PDMS) was applied to the enrichment of polychlorinated biphenyls (PCBs) from human sperm. The seven Ballschmiter PCBs were used as model compounds. The extracted PCBs were then thermally desorbed from the stir bar and analysed on-line by capillary gas chromatography (CGC) with mass spectrometric detection (MS). Method development started with the analysis of PCBs spiked in water. Methanol had to be added to the samples in order to reduce the influence of glass adsorption on recovery and reproducibility. Recoveries in water for all PCBs varied around 50-60% and were limited for low molecular mass (MM) PCBs by polarity changes in the sample due to methanol addition and for high MM PCBs by non-equilibrium conditions. Matrix suppression by the lipophilic medium lowered the recoveries in the sperm samples proportional with PCB polarity. The method was validated and although limits of detection (LOD) for the individual congeners were in the sub-ppt level (<pg/ml), the limit of quantification (LOQ) was set at 10 ppt (10 pg/ml).

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Sensitive gas chromatographic--mass spectrometric screening of acetylated benzodiazepines.

GC-MS screening conditions were developed for 15 low-dosed benzodiazepines, covering alprazolam, flunitrazepam, flurazepam, ketazolam, lorazepam and triazolam, and the corresponding metabolites alpha-hydroxyalprazolam, 4-hydroxyalprazolam; 7-aminoflunitrazepam, desmethylflunitrazepam, 7-aminodesmethylflunitrazepam; hydroxyethylflurazepam, N-desalkylflurazepam; oxazepam and alpha-hydroxytriazolam, respectively. Benzodiazepines are analyzed on a polydimethylsiloxane column in both the scan and the multiple ion monitoring modes using on-column injection to attain maximal sensitivity. The reactive compounds are acetylated with pyridine and acetic anhydride for 20 min. The derivatives are stable for at least 4 days. The relative standard deviation observed with standard compounds at the low nanogram-level ranged from 1.13 to 4.87% within-day and from 1.12 to 4.94% between-day. Unequivocal identification potential, high chromatographic resolution and sensitivity are combined with minimal thermal degradation. The presented screening conditions provide the basis for a unique routine screening method for low-dosed benzodiazepines with a broad polarity range.

Acetylation↗
PubMed2001

Characterization of a transformed rat retinal ganglion cell line.

The purpose of the present study was to establish a rat retinal ganglion cell line by transformation of rat retinal cells. For this investigation, retinal cells were isolated from postnatal day 1 (PN1) rats and transformed with the psi2 E1A virus. In order to isolate retinal ganglion cells (RGC), single cell clones were chosen at random from the transformed cells. Expression of Thy-1 (a marker for RGC), glial fibrillary acidic protein (GFAP, a positive marker for Muller cells), HPC-1/syntaxin (a marker for amacrine cells), 8A1 (a marker for horizontal and ganglion cells) and neurotrophins was studied using reverse transcriptase-polymerase chain reaction (RT-PCR), immunoblotting and immunocytochemistry. One of the retinal cell clones, designated RGC-5, was positive for Thy-1, Brn-3C, Neuritin, NMDA receptor, GABA-B receptor, and synaptophysin expression and negative for GFAP, HPC-1, and 8A1, suggesting that it represented a putative RGC clone. The results of RT-PCR analysis were confirmed by immunocytochemistry for Thy-1 and GFAP. Upon further characterization by immunoblotting, the RGC-5 clone was positive for Thy-1, negative for GFAP, 8A1 and syntaxin. RGC 5 cells were also positive for the expression of neurotrophins and their cognate receptors. To establish the physiological relevance of RGC-5, the effects of serum/trophic factor deprivation and glutamate toxicity were analyzed to determine if these cells would undergo apoptosis. The protective effects of neurotrophins on RGC-5 after serum deprivation was also investigated. Apoptosis was studied by terminal deoxynucleotidyl transferase-mediated fluoresceinated dUTP nick end labeling (TUNEL). Serum deprivation resulted in apoptosis and supplementation with both BDNF and NT-4 in the growth media, protected the RGC-5 cells from undergoing apoptosis. On differentiation with succinyl concanavalin A (sConA), RGC-5 cells became sensitive to glutamate toxicity, which could be reversed by inclusion of ciplizone (MK801). In conclusion, a transformed rat retinal cell line, RGC-5, has certain characteristics of retinal ganglion cells based on Thy-1 and Brn-3C expression and its sensitivity to glutamate excitotoxicity and neurotrophin withdrawal. These cells may be valuable in understanding of retinal ganglion cell biology and physiology including in vitro manipulations in experimental models of glaucoma.

Animals↗
PubMed2001

Neurotrophin and neurotrophin receptor expression by cells of the human lamina cribrosa.

PURPOSE: To determine whether cells and tissue from the human lamina cribrosa (LC) express neurotrophin and tyrosine kinase (trk) receptor mRNA and protein and whether these cells secrete neurotrophins. METHODS: Synthesis of cDNA and the reverse transcription-polymerase chain reaction (RT-PCR) were conducted using total RNA obtained from well-characterized cell lines from the human LC and human optic nerve head (ONH) tissue. Immunofluorescent localization and Western blot analysis were used to evaluate neurotrophin and trk protein expression in cells and tissue from the human LC. Immunoassay systems (ELISAs) were used to detect the secretion of neurotrophins. RESULTS: Two morphologically distinct cell types (LC cells and ONH astrocytes) were isolated and characterized from the human LC. Messenger RNA for each of the neurotrophins, three full-length trk receptors and two truncated trk receptors were detected in both cell types and in human ONH tissue. Protein for the neurotrophins and trk receptors were detected in LC cells, ONH astrocytes, and ONH tissue. Neither cell type expressed mRNA or protein for the low-affinity neurotrophin receptor p75. The secretion of neurotrophins was observed in both cell types. CONCLUSIONS: Cells from the human LC express mRNA and protein of neurotrophins and trk receptors. In addition, cells from the LC secrete neurotrophins, which suggests that there is paracrine and/or autocrine signaling within the LC. Neurotrophin signaling within this region of the ONH may play important roles in the maintenance of the normal LC and in such diseases as glaucoma.

Blotting, Southern↗
PubMed2000

Quantitative determination of paraquat in a fatal intoxication by HPLC-DAD following chemical reduction with sodium borohydride.

A fatality due to a massive ingestion of paraquat is presented. Screening by enzyme-multiplied immunoassay of postmortem blood and urine disclosed the presence of tricyclic antidepressants (in urine only), benzodiazepines, cotinine, and caffeine. Further analysis of blood, urine, and stomach contents with thin-layer chromatography, high-performance liquid chromatography (HPLC), and gas chromatography confirmed the results found in the preliminary routine screening. It also revealed the presence of paraquat in blood, urine, and stomach contents, of diethyl parathion in urine and stomach contents, and of mevinphos in blood and stomach contents. Quantitation of paraquat was performed using HPLC with diode-array detection. Sample preparation involved a protein-precipitation step using trichloroacetic acid (necessary only for blood and tissue homogenate), followed by a chemical reduction with sodium borohydride of the fully ionized paraquat to a diene, which is amenable to solvent extraction. Quantitative results were obtained for all postmortem matrices available: blood, 5.05 mg/L; urine, 6.00 mg/l; stomach contents, 17.2 g/L; liver, 4.86 mg/kg; and kidney, 80.6 mg/kg. The paraquat distribution in this case is compared with analytical findings reported in the literature. As would be expected, concentrations found in fatal paraquat intoxications display large differences. The data presented illustrate the outspoken lethal nature of the herbicide paraquat and the ongoing appearance of this compound in deadly accidental and suicidal poisonings.

Borohydrides↗
PubMed2000

Human trabecular meshwork cells secrete neurotrophins and express neurotrophin receptors (Trk).

PURPOSE: The purpose of this study was to compare the mRNA expression of neurotrophins (NTs) and NT receptors (Trk) in cultured human trabecular meshwork (HTM) cells and ex vivo HTM tissues, to immunolocalize both NT and Trk receptors in cultured HTM cells, and to demonstrate secretion of NTs by HTM cells. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression of NT and Trk receptor mRNAs in early-passaged, cultured HTM cells from donors of several ages. RT-PCR was used on ex vivo HTM tissues from donors to compare and contrast mRNA expression with cell culture results. In addition, immunohistochemistry was used to localize the translated NT and low- (p75) and high- (Trk) affinity NT receptor proteins within cultured HTM cells and trabecular meshwork tissues. Last, enzyme-linked immunoassay (ELISA) was used to demonstrate secretion of NTs by HTM cells. RESULTS: Amplification products of the expected size for NTs were detected in both cultured HTM cells and ex vivo HTM tissues. Specifically identified were amplification products for the following NTs: NGF, BDNF, NT-3, and NT-4. Amplification products for the full-length Trk A and Trk C high-affinity receptor were observed, as well as truncated isoforms for Trk B and Trk C. No amplification products were produced for the full-length Trk B receptor nor for the low-affinity p75 receptor. Immunohistochemistry indicated that proteins for the various NTs and full-length and truncated Trk receptors were translated by cultured HTM cells and tissues. Immunoassays (ELISA) detected BDNF, NT-4, NGF, and NT-3 in the culture media from HTM cells. CONCLUSIONS: The results demonstrate, for the first time, mRNA expression for NT and Trk receptors by both cultured HTM cells and ex vivo HTM tissues. NTs were immunolocalized in HTM tissues and cultured HTM cells are capable of secreting NTs. Specific NTs acting through high-affinity Trk receptors within the HTM may be involved in maintaining the normal function of this complex tissue.

Adolescent↗
PubMed1999

Fas-activated apoptosis and apoptosis mediators in human trabecular meshwork cells.

A gradual loss of cells occurs within the human trabecular meshwork during normal aging and appears to be increased in patients with primary open-angle glaucoma. The exact mechanism by which cells are lost in either condition is not known, however phagocytosis, cell migration and cell death have been suggested. Apoptosis is one method by which cell death can occur. We have examined the modulators for apoptosis within the human trabecular meshwork using both cell lines and ex-vivo dissected trabecular meshwork tissues obtained from normal donors. Using RT-PCR it was shown that mRNA for several modulators of apoptosis (Fas, Bcl-2, Bcl-xl, Bax, and ICE) are expressed by both cell lines and ex-vivo tissues. Apoptosis was stimulated to occur by treating cell lines with a monoclonal antibody (IgM) to Fas. Apoptosis was verified via morphological changes to the cells, transferase-mediated dUTP nick-end labeling TUNEL Immunofluorescence, and DNA laddering. Control cells exposed to IgM did not undergo apoptosis. These results represent the first report of apoptosis modulators within the human trabecular meshwork and demonstrate that human trabecular meshwork cells can be stimulated to undergo apoptosis via the Fas/FasL pathway.

Aged↗
PubMed1999

Expression of alternatively spliced growth factor receptor isoforms in the human trabecular meshwork.

PURPOSE: Growth factors act through high-affinity cell surface receptors expressed by target cells and are critical modulators of cell function. Because aqueous humor is known to contain growth factors, these molecules may play a key role in maintaining the normal function of the human trabecular meshwork (HTM). Alternate mRNA splicing is an important mechanism used by cells to generate diverse isoforms of growth factor receptors. Although previous investigators have suggested that HTM cells may express alternative isoforms of several growth factor receptors, there have been no studies to verify these preliminary findings. The objective of this study was to determine whether cultured and ex vivo HTM cells express alternate isoforms of hepatocyte, keratinocyte, and transforming growth factor beta (TGFbeta)-II receptors and to characterize the isoform molecular sequences. METHODS: To determine whether cells within the HTM express mRNA for alternate isoforms of growth factor receptors, total RNA was isolated from several well-characterized HTM cell lines that were established from donors of various ages and from fresh ex vivo HTM tissues from healthy donors. After cDNA synthesis, polymerase chain reaction was initiated using specific primers for alternate forms of the following receptors: hepatocyte growth factor (HGFR), keratinocyte growth factor (KGFR), and transforming growth factor beta receptor II (TGFbetaR-II). Specificity and characterization of the polymerase chain reaction amplification products were determined by nucleic acid sequencing. RESULTS: Amplification products of the expected size for the growth factor isoforms were expressed in cell lines and in ex vivo tissues. Nucleic acid sequencing showed that cultured HTM cells and fresh ex vivo trabecular meshwork tissues expressed specific mRNA for alternatively spliced isoforms of HGFR, KGFR, and TGFbetaR-II The HGFR alternate isoform contained a 96-bp insert in the C-terminal coding region of the cytoplasmic tyrosine kinase domain. The KGFR alternate isoform is a soluble, truncated form, because it has no transmembrane or cytoplasmic domain as does the normal membrane-associated form. The TGFbetaR-II alternate isoform contained a 75-bp insert in the N-terminal coding region of the extracellular domain. CONCLUSIONS: In vitro and ex vivo HTM cells express mRNA for alternatively spliced isoforms of HGFR, KGFR, and TGFbetaR-II. These alternatively spliced receptor isoforms may be functional within the HTM and may play a critical role in maintaining the normal microenvironment of this important tissue.

Aged↗
PubMed1998

The effectiveness of low dose tranexamic acid in primary cardiac surgery.

PURPOSE: This randomized controlled clinical trial compared three doses of tranexamic acid (TA) in primary cardiac surgery in terms of blood loss and transfusion requirements. METHODS: Patients presenting for primary coronary artery bypass grafting (CABG) and/or valve replacement were randomly assigned to one of three TA regimens: 20 mg.kg-1 (LD), 50 mg.kg-1 (MD), and 100 mg.kg-1 (HD). All participants and staff were blinded to the allocation. Haemoglobin (Hgb), haematocrit and platelet count were determined preoperatively, after bypass, at CCA arrival, and 12 and 24 hr after surgery. Coagulation parameters were measured before and after surgery. Blood loss was measured intraoperatively and for 24 hr postoperatively following a standardized protocol. Blood products were administered in a standardized fashion. RESULTS: Two hundred twenty patients completed the trial over 10 months: 74 in LD, 75 in MD and 72 in HD dose groups. All patients groups were comparable; similar procedures were performed in each group. No differences were identified for blood loss intra-operatively (490 +/- 232 ml, 523 +/- 413 ml, 488 +/- 357 ml, respectively), 24 hr post-operatively (543 +/- 223 ml, 544 +/- 231, 458 +/- 210 ml, respectively), and overall (1032 +/- 358 ml, 1067 +/- 502 ml, 946 +/- 459 ml, respectively). Blood product administration was similar in the three groups. No differences in postoperative complications were found. CONCLUSIONS: This study demonstrates the equivalency of the three doses of TA in primary cardiac surgical procedures. The use of low dose (20 mg.kg-1) TA results in comparable outcomes, without additional complications.

Analysis of Variance↗
PubMed1998

Clinical outcome, consumer satisfaction, and ad hoc ratings of improvement in children's mental health.

Mental health clinics and managed care organizations assess treatment effectiveness with consumer satisfaction measures and ad hoc measures of improvement obtained from a single informant; some of these measures are as simple as asking clients whether they improved during treatment. In the present correlational study of 199 treated adolescents, we used a multitrait-multimethod analysis to examine psychometrically measured pathology change (pre- and postassessment of symptoms and functioning), consumer satisfaction, and perceived improvement reported by multiple informants. Confirmatory factor-analytic results indicate that (a) outcome variance due to multiple informants cannot be ignored, (b) consumer satisfaction is unrelated to pathology change, and (c) parent-reported perceived improvement ratings are more akin to satisfaction than to pathology change.

Adolescent↗
PubMed1998

Psychopathology associated with sexual abuse: the importance of complementary designs and common ground.

In their recent longitudinal study of youth victimization and consequent traumatization, S. Boney-McCoy and D. Finkelhor (1996) contrast their position with previous retrospective research (S. Harter, P. Alexander, & R. A. Neimeyer, 1988; M. R. Nash, T. C. Hulsey, M. C. Sexton, T. L. Harralson, & W. Lambert, 1993a), arguing that their data support the impact of victimization per se, independent of the moderating effect of family environment. Because Boney-McCoy and Finkelhor's argument may misrepresent the results of such studies, this article (a) clarifies the actual findings of previous retrospective studies of abuse, (b) suggests methodological limitations both in Boney-McCoy and Finkelhor's research and in that of S. Harter et al., 1998, and M. R. Nash et al., 1993a, that should be remedied by future investigators, and (c) argues that both retrospective clinical research and prospective community surveys converge on a common ground, namely, that specific abuse experiences can best be understood and investigated in the context of the prior, contemporaneous, and subsequent family environments in which they occur.

Adolescent↗