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Biomedical subjects

J Lambert

Publications and source records attributed to J Lambert.

At least 19 recordsLinked to original sources
PubMed2006

A plastic scintillation dosimeter for high dose rate brachytherapy.

In vivo dose verification in brachytherapy requires a small insertable dosimeter with a real-time readout capability. Fibre optic scintillation dosimeters, consisting of a plastic scintillator coupled to an optical fibre, are one of the most promising dosimeters for this application. We have developed two sizes of the BrachyFOD scintillation dosimeter which have external diameters of 2.2 mm and 1 mm and have determined their important dosimetric characteristics (depth dose relation, angular dependence, temperature dependence, energy dependence). We have shown that the background signal created by Cerenkov and fibre fluorescence does not significantly affect the performance in most clinical geometries using an (192)Ir source from an HDR brachytherapy unit. The dosimeter design enables readout at less than 0.5 s intervals. The BrachyFOD satisfies the need for a real-time in vivo brachytherapy dosimeter.

Brachytherapy↗
PubMed2006

Why are children still being infected with HIV? Experiences in the prevention of mother-to-child transmission of HIV in south London.

OBJECTIVES: To evaluate the effectiveness of interventions to prevent mother-to-child transmission of HIV at a large teaching hospital in South East London, and to assess reasons for the small numbers of transmissions that continue to occur. DESIGN: A database of all pregnant women diagnosed as HIV positive between 1993 and 2005 was reviewed, with detailed (retrospective) case-note review of all mother-infant pairs where HIV transmission occurred. SETTING: King's College Hospital, London, UK, a teaching hospital serving an ethnically diverse and socially deprived population. RESULTS: 296 pregnancies to 274 women were recorded. 9 of 296 (3.0%) women were lost to follow-up before the end of the pregnancy. Of 287 pregnancies followed up until after delivery, 6 (2.1%) resulted in HIV infection in the infant. More recently, between 2000 and 2004, this transmission rate was even lower, at 3 in 231 (1.3%). Each of these six women had complications, including late presentation to services and defaulting follow-up appointments, which were likely to increase the risk of HIV transmission. Four of the six transmissions occurred in utero. CONCLUSION: The overall transmission rate of 2% attests to the efforts of the multidisciplinary care team in managing this population which is often hard to reach. Clearly, good systems are needed to trace those women who default. Further data are needed regarding in utero transmissions.

Adolescent↗
PubMed2006

Adsorption studies of recalcitrant compounds of molasses spentwash on activated carbons.

Due to high levels of residual chemical oxygen demand (COD) in the effluent of molasses spentwash (MSW) after anaerobic treatment, acceptable COD levels for discharge cannot be achieved without some form of post-treatment. In this study, the particulate composition of molasses spentwash after anaerobic digestion (MSWD), is characterised as to its particle size distribution, using micro- and ultrafiltration and three activated carbons are characterised as to their ability to reduce significantly the COD of MSWD effluent. The activated carbons tested as adsorbent, were characterised by XPS spectroscopy, elemental analysis, surface area, pore size distribution, and acid-base titration using the Boehm's method. Adsorption of phenol, used here as a reference compound, and of some organic compounds contained in MSWD (gallic acid, tannic acid, and melanoidin, respectively), was studied. It was clearly demonstrated that an activated carbon with a significant distribution of both micropores and mesopores and a significant amount of macropores that are assumed to act as conduits providing access to micro- and mesopores, have a good adsorption efficiency for compounds such as tannic acid and melanoidins. It is a good adsorbent for melanoidin and coloured compounds of MSWD, which represents a large source of the aqueous pollution in sugar cane industries.

Adsorption↗
PubMed2006

Economic evaluation of methyl aminolaevulinate-based photodynamic therapy in the management of actinic keratosis and basal cell carcinoma.

BACKGROUND: Various effective therapeutic options are currently available for the treatment of actinic keratosis (AK) and basal cell carcinoma (BCC), but none is perfect. Poor cosmesis resulting from surgical procedures and skin irritation induced by topical agents remain significant problems. OBJECTIVES: To evaluate the cost-effectiveness of a recent approach, methyl aminolaevulinate-based photodynamic therapy (MAL-PDT; Metvix; Galderma, Lausanne, Switzerland) in AK and BCC. METHODS: A medical decision tree was developed for simulation of all possible outcomes associated with the medical decision to apply MAL-PDT or a comparator. The time horizon was 1 year for AK and 5 years for BCC. The comparators were cryotherapy in AK and excision surgery in BCC. Clinical data for the model were obtained from the literature. Data on medical management resulted from a Delphi panel performed among 12 Belgian dermatologists. Based on the model, the cost per full responder was calculated, whereby a responder was defined as a patient with all lesions clinically responding and showing an excellent cosmetic result. RESULTS: MAL-PDT is a more expensive treatment compared with cryotherapy for AK. However, the cost per full responder is comparable with cryotherapy (euro363 and euro379, respectively). Incremental cost per extra full responder is euro401. Incremental cost per full responder is euro469 for nodular BCC and euro251 for superficial BCC, both compared with excision surgery. CONCLUSIONS: The results suggest that MAL-PDT is a cost-effective intervention in AK taking a 1-year time horizon, if society is willing to pay euro1.50 per day of response, and that MAL-PDT is better value for money than excision in BCC, taking a 5-year time horizon.

Aminolevulinic Acid↗
PubMed2006

Investigation of the p.Ser278Arg polymorphism of the autoimmune regulator (AIRE) gene in alopecia areata.

A recent study has suggested that the g.961C >G (p.Ser278Arg) variant of the autoimmune regulator (AIRE) gene contributes to susceptibility to alopecia areata (AA). We attempted to replicate this finding using a case-control sample of Belgian-German origin (273 patients and 283 controls). Despite adequate power, our study results do not support a significant association of the risk allele in our AA patient sample. This remained the case when we stratified our sample according to severity and family history of disease. Our study results do not support the hypothesis that the g.961C >G (p.Ser278Arg) polymorphism of the AIRE gene is associated with an increased risk for AA.

Alleles↗
PubMed2005

Intrafractional motion during proton beam scanning.

Patient and internal organ motion during treatment with a scanned proton beam can introduce unplanned heterogeneities in the dose distribution throughout the irradiated volume. With static beam techniques, a margin around the target volume is added to compensate for patient and organ motion. This margin may not provide the solution with dynamic beam scanning. Intrafractional motion parallel and perpendicular to the beam axis is studied using two different scanning methods on a cubic water phantom. The direction of motion relative to the beam scanning direction as well as the method of scanning the proton beam across the target has a significant effect on the resulting dose distribution within the target volume. In the extreme cases studied here up to 100% of the target receives a dose outside the recommended limits, with a minimum dose as low as 34% of the prescribed dose.

Algorithms↗
PubMed2005

[The neurobehavioral rating scale-revised: assessment of concurrent validity].

UNLABELLED: Cognitive and behavioral impairment are a major source of disability in daily living of patients with traumatic brain injury (TBI). The Neurobehavioral Rating Scale-Revised (NRS-R) is a short, easy-to administer interview tool developed to improve assessment by clinicians. Data are available on its criterion validity and reliability, but the concurrent validity of the French NRS-R was not yet documented. OBJECTIVE: To assess the concurrent validity of the NRS-R with current psychometric tests. METHOD: One hundred and four patients with TBI enrolled in a community adjustment program underwent concurrent examination with the NRS-R, cognitive tests assessing memory, attention, and executive functions, and scales of anxiety (STAI) and depressive mood (CES-D). Intercorrelations were undertaken between these variables and the five factors of the NRS-R: F1, intentional behavior; F2, lowered emotional state; F3, survival-oriented behaviour/hightened emotional state; F4, arousal state; and F5, language. Patients were 82 men and 22 women, the mean age was 28.5 years, and 70% had severe TBI (Glasgow coma score [GCS] below 8 on admission). They were assessed 52 months on average after their injury. RESULTS: Factor F1 was correlated with results on the GCS (P<0.05), the Tower of London test (TL, P<0.01), the Trail Making Test (TMT, P<0.01), divided attention (DA) and inhibition (IN) subscales of the Zimmermann and Fimm's Attention battery (TEA) (P<0.01) and reverse digit span (DS, P<0.05). Factor F2 was positively related to age at injury, time since injury (TSI) (P<0.05) and CESD and STAI scores (P<0.001). Factor F3 was related to DA (P<0.01) TL scores and TSI (P<0.05). Factor F4 was related to TL, TMT, DA, flexibility, DS (P<0.05), TSI, duration of post-traumatic amnesia, CES-D score (P<0.05) and STAI scores (P<0.01). Factor F5 was related to GCS, DA (P<0.05), and reaction time on the subscales IN and Go/nogo (GO) of the TEA battery (P<0.01). The NRS-R total score was related to CESD, STAI scores, TMT score, DA (P<0.01) and TL score, IN and GO scores and TSI (P<0.05). DISCUSSION: As McCauley et al found with the English version of the NRS-R, significant relationships were found between NRS-R factor scores, cognitive tests and emotional scales. Relationships were also found between factor scores and indicators of injury severity and time since injury. These data suggest fair concurrent validity of the NRS-R.

Adolescent↗
PubMed2005

[Pregnancy termination between 12 and 14 weeks gestation: practices and early complications in comparison with termination between 8 and 12 weeks].

OBJECTIVES: To describe and compare practices and complications of induced abortions (IA) between 12 and 14 gestational weeks (GW) with those performed at lower terms (8-10 and 10-12 GW). PATIENTS AND METHODS: Cohort study enrolled in two IA centers 411 women, 147 of them with 12-14 weeks gestation. Comparisons were made according to pregnancy term (8-10, 10-12 and 12-14 GW). RESULTS: Pregnancy term influenced the technical conditions of IA. Number and diameter of dilators and suction cannula as well as surgery time increase with gestational age--whether priming agents were used or not. Pain felt during surgery and early complications (within 15 days post IA) did not increase with gestational age. CONCLUSION: Results of this study show that IA between 12 and 14 GW are as feasible as with lower terms.

Abortion, Induced↗
PubMed2005

Case-control study to identify melanoma risk factors in the Belgian population: the significance of clinical examination.

BACKGROUND: Although numerous studies have evaluated risk factors associated with cutaneous malignant melanoma (CMM), no such study has been carried out in Belgium. OBJECTIVES: To identify individuals who are at high risk of developing malignant melanoma in Belgium, which could enhance the efficacy of screening interventions and avoid unnecessary skin inspections. STUDY DESIGN/SETTING/SUBJECTS: We prospectively included patients who were diagnosed with invasive malignant melanoma between 1998 and 2001 at the Department of Dermatology in a case-control study. Controls were selected from the outpatient dermatology clinic. Participants were interviewed and clinically examined by a dermatologist. We asked questions concerning most known risk factors associated with malignant melanoma such as phenotypical and skin characteristics, and environmental and lifestyle exposures. To adjust for confounding variables and to estimate odds ratios (ORs) and 95% confidence intervals (CIs), a multivariate model was used. RESULTS: Although sunburn in childhood and substantial occupational solar exposure were modestly, but significantly, associated with malignant melanoma risk, clinical examination yielded several stronger risk factors. In a multivariate model, which adjusted for age, gender and skin phototype, phenotypical characteristics such as skin, hair and eye colour were significantly associated with the development of malignant melanoma. In the multivariate model, people with three or more atypical naevi were at more than 10-fold risk of developing a malignant melanoma (> or = 3 atypical naevi; adjusted OR = 11.40, 95% CI = 4.79-17.53) compared to those without an atypical naevus. The presence of one or more palpable naevi on the upper extremities or having solar lentigines increased the odds of developing malignant melanoma at least twofold. CONCLUSIONS: In Belgium, risk factors associated with malignant melanoma appear to be in accordance with previous studies. To assess peoples' risk profile, clinical skin examination is likely to yield the most important sporadic malignant melanoma risk factors. Therefore, focusing screening campaigns on individuals with predefined findings on skin self-examination may increase its efficacy.

Belgium↗
PubMed2005

A prospective multicenter study of the efficacy and tolerability of cryopreserved allogenic human keratinocytes to treat venous leg ulcers.

Allogeneic human keratinocyte cultures have been used to treat burn wounds, donor sites, and chronic skin ulcers with some success. Cryopreservation of these cultures allows for the production of large standardized batches that are readily available for use. The aim of the study presented in this report was to study effects of cryopreserved cultured allogenic human keratinocytes (CryoCeal) on chronic lower extremity wounds. Parameters were measured to study efficacy, tolerability, pain associated with chronic wounds, and quality of life of patients. Twenty-seven patients with hard-to-heal venous leg ulcers received a maximum of 9 applications of CryoCeal in a prospective, uncontrolled multicenter study lasting 48 weeks. Eleven out of 27 patients (41%; 95% CI: 22%-61%) had complete wound closure within 24 weeks (1 week). The time required for complete wound closure in these 11 patients ranged from 4.1 to 24.9 weeks. Only 1 patient had recurrence of the ulcer at 48 weeks. Local (wound) pain scores decreased from a mean of 2.5 at baseline to 0.9 at week 24. Fifty percent of the patients attained a pain score of 0 after 12 weeks and remained stable at this score until the end of the study. Overall, the patient quality of life was better at week 24, compared to baseline values. The treatment was well tolerated, and wound infection was the most frequently occurring adverse event.

Adult↗
PubMed2005

Bortezomib-induced Sweet's syndrome.

Sweet's syndrome is an uncommon acute skin disease, associated with a variety of medical problems. The drug-induced variant is even rarer. We describe two cases of this syndrome associated with the administration of the proteasome inhibitor bortezomib. The diagnostic criteria for drug-induced Sweet's syndrome as proposed by Walker and Cohen were fulfilled. Vasculitis and neutrophilic eccrine hidradenitis were excluded.

Aged↗
PubMed2004

[Relatively poor regulation of blood pressure in patients with type-2 diabetes mellitus in the primary care setting and specialists' practice in the Netherlands].

OBJECTIVE: To investigate the degree to which the goals for adequate blood-pressure control in patients with type-2 diabetes mellitus (DM) are met in Dutch specialists' practice and in the primary-care setting. DESIGN: Cross sectional. METHOD: Data were collected from all consecutive patients with DM type 2 visiting the outpatient clinic of two physicians specialised in diabetes care, in Zwolle, the Netherlands, in the period 1 November 1999-30 April 2000. The target value for blood pressure was < or = 150/85 mmHg. In addition, baseline data were collected on patients in the primary-care setting who participated in a transmural project in Zwolle in the period 1 February 1997-31 January 1998. In 1998, the target blood pressure in the primary-care setting was < or = 160/90 mmHg. Patients who met the goals for adequate blood-pressure control were compared with patients who did not. RESULTS: A total of 502 patients from specialists' practice and 1084 patients from the primary-care setting were included. The prevalence of hypertension in specialists' practice was 89% (n = 377); of these patients, 140 (37%) had a good regulation of their blood pressure. The patients who had an adequate blood-pressure control and those who did not were comparable. Both groups were prescribed an average of 2.2 kinds of antihypertensive agent per patient. The prevalence of hypertension in the primary care was 69% (n = 733). The goal for adequate blood-pressure control, i.e. a blood pressure of < or = 160/90 mmHg, was achieved in 44% (n = 324). In the primary-care setting, an average of 1.1 kinds of antihypertensive agent was prescribed, 1.6 in patients who achieved the target value and 0.8 in those who did not (p < 0.05). CONCLUSION: Regulation of blood pressure in patients with type 2 DM and hypertension was far from optimal: 37% of patients in specialists' practice and 44% of those in the primary-care setting achieved the target values.

Aged↗
PubMed2004

Simple modeling of dipolar coupled 7Li spins and stimulated-echo spectroscopy of single-crystalline beta-eucryptite.

Stimulated-echo spectroscopy has recently been applied to study the ultra-slow dynamics of nuclear spin-3/2 probes such as 7Li and 9Be in solids. Apart from the dominant first-order quadrupolar interaction in the present article also the impact of the homonuclear dipolar interactions is considered in a simple way: the time evolution of a dipole coupled pair of spins with I = 3/2 is calculated in an approximation, which takes into account that the satellite transitions usually do not overlap. Explicit analytical expressions describing various aspects of a coupled quadrupolar pair subjected to a Jeener-Broekaert pulse sequence are derived. Extensions to larger spin systems are also briefly discussed. These results are compared with experimental data on a single-crystalline Li ion conductor.

Journal Article↗
PubMed2004

Synthesis and evaluation of a thymidine analog for positron emission tomography study of tumor DNA proliferation in vivo.

This study describes the synthesis, radiolabelling and biological evaluation of 5-(2,4-difluoro-5-[18F]fluoromethyl-phenyl)-2-hydroxymethyl-tetrahydrofuran-3-ol, 13. Radiolabelling was achieved by reaction of the tosylate 3 with K[18F] in the presence of Kryptofix 222. Good stability in saline and serum solutions at physiological temperatures in vitro was observed. A cell incorporation study of 13 using SW1222 tumor cells showed a linear uptake, unfortunately, in vivo studies indicated that 13 was undergoing defluorination. Rapid defluorination of the radiotracer was confirmed by an in vitro stability study in blood plasma. Finally, a comparison between the DNA uptake of 13 and tritiated thymidine was performed in vitro to asses the potential utility of more stable analogs. These studies showed that 13 and its analogs are unsuitable as potential tracers to image DNA proliferation and highlighted the difficulty in predicting the in vivo stability of novel radiotracers.

Animals↗
PubMed2004

Cyclooxygenase-2 expression and angiogenesis in squamous cell carcinoma of the skin and its precursors: a paired immunohistochemical study of 35 cases.

BACKGROUND: Cyclooxygenase (COX)-2 expression and tumour-induced angiogenesis appear to be increased in squamous cell carcinoma (SCC) of the skin. In other cancers, COX-2 is a pro-angiogenic factor. The association between angiogenesis and COX-2 has not been studied in skin cancer. OBJECTIVES: To assess the onset of increased COX-2 expression and angiogenesis in the multistage carcinogenesis of SCC as well as the correlation between those two parameters. PATIENTS/METHODS: We performed a retrospective paired immunohistochemical analysis of normal skin, actinic keratosis (AK), Bowen's disease (BD) and SCC among 35 individuals. Specimens were considered COX-2 immunopositive when 5% or more of the tumour cells showed clear evidence of immunostaining. To quantify active angiogenesis, we used a Ki-67-CD34 double-labelling immunohistochemical stain and calculated the fraction of proliferating endothelial cells. The Chalkley method was used to determine the microvessel density. To detect hypoxia, a carboanhydrase IX immunostain was used. RESULTS: Compared with normal epidermis (0%), AK (31%), BD (22%) and SCC (40%) were significantly more likely to be COX-2 immunopositive (P < 0.01). The fraction of proliferating endothelial cells and the Chalkley scores paralleled multistage carcinogenesis (P < 0.05 between different stages). COX-2 immunopositivity was fairly correlated with hypoxia and higher proliferating endothelial cell fractions but not with Chalkley counts. CONCLUSIONS: Induction of COX-2 expression and angiogenesis are both early events in the development of SCC. In addition to ultraviolet light, hypoxia and COX-2 may be involved in skin tumour angiogenesis.

Adult↗
PubMed2004

[How I treat... Belgian consensus document on the treatment of acne].

This article describes the consensus on the treatment of acne, reached by a Belgian working group. An effective treatment has to rely as much as possible on the pathophysiologic factors: the increased production of sebum, the abnormal desquamation (retention hyperkeratosis) of the epithelium of he sebaceous gland, the proliferation of Propionibacterium acnes and inflammation. The therapeutic arsenal contains topical as well as systemic drugs. This consensus gives an overview of both modalities and an algorithm is presented describing the practical approach to acne treatment.

Acne Vulgaris↗
PubMed2003

Pharmacoeconomic issues in onychomycosis.

The importance of health economics (the application of economics to healthcare and medicine) has grown significantly in recent years as the need to maximize the use of limited healthcare resources has increased. The role of pharmacoeconomics (the application of health economics to pharmaceuticals) is to provide a method that evaluates outcomes and costs of treatment at the same time, thus providing an aid to better decision-making. However, there remains some uncertainty within the medical community about the usefulness of pharmacoeconomic data. Reasons for this include a poor understanding of the purpose and outcome of pharmacoeconomic studies, inconsistent use of terminology, and a perception that freedom of choice of prescriptions is restricted. To optimize the medical management of patients with severe onychomycosis, two pharmacoeconomic evaluations of amorolfine were undertaken. In a comparison of topical amorolfine + oral terbinafine vs. oral terbinafine alone, treatment with the topical/oral combination for a period of up to 12 weeks resulted in an improved outcome compared with the oral drug alone. A second study with topical amorolfine + oral itraconazole showed that treatment for a period of 6 weeks was the preferred cost-effective treatment option. While combination therapy might seem to be a more costly option, pharmacoeconomic studies have clearly shown that treatment of onychomycosis with amorolfine, in combination with either oral terbinafine or oral itraconazole, is both cost-saving and cost-effective compared with oral treatment alone.

Antifungal Agents↗