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Biomedical subjects

G Thomas

Publications and source records attributed to G Thomas.

At least 19 recordsLinked to original sources
PubMed2006

RET rearrangements in post-Chernobyl papillary thyroid carcinomas with a short latency analysed by interphase FISH.

Tissue samples from 13 post-Chernobyl childhood thyroid tumours that occurred within a short period of time (4-8 years) after the Chernobyl accident have been investigated by interphase FISH analysis for rearrangements of RET. In all, 77% of cases showed RET/PTC rearrangements and a distinct intratumoural genetic heterogeneity. The data were compared to findings on 32 post-Chernobyl PTCs that occurred after a longer period of time (9-12 years) after the accident. In none of the cases from either group were 100% of cells positive for RET rearrangement. In addition, the pattern of RET-positive cells was different in the two groups (short vs longer latency). A significant clustering of aberrant cells could be detected in the long-latency subgroup, whereas the aberrant cells were more homogeneously distributed among the short-latency tumours. The findings suggest that oligoclonal tumour development occurs in post-Chernobyl PTCs. This pattern of different clones within the tumour appears to become more discrete in cases with longer latencies, suggesting either outgrowth of individual clones or development of later subclones with time.

Adolescent↗
PubMed2006

[Identification and management of HNPCC syndrome (hereditary non polyposis colon cancer), hereditary predisposition to colorectal and endometrial adenocarcinomas].

BACKGROUND: The HNPCC syndrome (hereditary nonpolyposis colon cancer) is an inherited condition defined by clinical and genealogical information, known as Amsterdam criteria. In about 70% of cases, HNPCC syndrome is caused by germline mutations in MMR genes, leading to microsatellite instability of tumor DNA (MSI phenotype). Patients affected by the disease are at high risk for colorectal and endometrial carcinomas, but also for small intestine, urothelial, ovary, stomach and biliary tract carcinomas. HNPCC syndrome is responsible for 5% of colorectal cancers. Identification and management of this disease are part of a multidisciplinary procedure. METHODS: Twelve experts have been mandated by the French Health Ministry to analyze and synthesize their consensus position, and the resulting document has been reviewed by an additional group of 4 independent experts. MAIN RECOMMENDATIONS: The lack of sensitivity of Amsterdam criteria in recognizing patients carrying a MMR germline mutation led to an enlargement of these criteria for the recruitment of possible HNPCC patients, and to a 2-steps strategy, asking first for a tumor characterization according to MSI phenotype, especially in case of early-onset sporadic cases. The identification of germline MMR mutations has no major consequence on the cancer treatments, but influences markedly the long-term follow-up and the management of at-risk relatives. Gene carriers will enter a follow-up program regarding their colorectal and endometrial cancer risks, but other organs being at low lifetime risk, no specific surveillance will be proposed.

Adenocarcinoma↗
PubMed2006

Y-duplication of the male urethra: use of anterior anorectal wall for posterior urethral lengthening.

We have approached two patients with Y-duplication of the male urethra by a new two-staged technique to provide better results. A strip of anterior anorectal wall in continuity with the posterior urethra was used for posterior urethral lengthening and a tubed pedicled prepucial flap was used to reconstruct the anterior urethra without using the native urethra. This was done under a covering colostomy. After a gap of 6 months to allow for healing of the anorectum and to ensure adequate functioning of the perineal neourethra, second stage reconstruction was done using buried scrotal tube for the mid urethra along with colostomy closure. On follow-up at 8 and 12 months, respectively, both children were well with no stricture or fistula. There was normal anal continence and no stenosis. This technique tackles the problem in Y-duplication of the male urethra of lengthening the posterior urethral channel, which is often difficult to bring to the anterior half of the perineum especially if the opening is high up in the anorectum (case 2).

Child↗
PubMed2006

Psychosocial impact of the teacher's voice throughout the career.

It is generally accepted that vocal performance decreases with age. This decrease can be expected to be more pronounced in voice loading professions, which may lead to occupational dysphonia. The aim of this study was to investigate the course of voice complaints, experienced handicap, and absenteeism of work due to voice problems throughout the teaching years. Questionnaires were distributed among teachers of primary and secondary education, and 1875 were analyzed. The questionnaire was designed in such a way that personal aspects and questions about periods with symptoms and absence from work were included. The Voice Handicap Index (VHI) developed by Jacobson et al was sent along with the questionnaire. Surprisingly, a significant decrease of voice complaints during the career of the teachers was observed. The expectation that the percentage of teachers with a history of voice problems should experience more psychosocial impact, measured with the VHI, along their professional career could not be confirmed by this study. These results indicate that serious attention has to be paid to teachers with voice complaints. The fact that teachers in the beginning of their career complain more than in the end of their career emphasizes the importance of adequate aimed prevention programs for future teachers and for starting teachers with regard to their voice.

Adult↗
PubMed2006

Heart sound cancellation from lung sound recordings using time-frequency filtering.

During lung sound recordings, heart sounds (HS) interfere with clinical interpretation of lung sounds over the low frequency components which is significant especially at low flow rates. Hence, it is desirable to cancel the effect of HS on lung sound records. In this paper, a novel HS cancellation method is presented. This method first localizes HS segments using multiresolution decomposition of the wavelet transform coefficients, then removes those segments from the original lung sound record and estimates the missing data via a 2D interpolation in the time-frequency (TF) domain. Finally, the signal is reconstructed into the time domain. To evaluate the efficiency of the TF filtering, the average power spectral density (PSD) of the original lung sound segments with and without HS over four frequency bands from 20 to 300 Hz were calculated and compared with the average PSD of the filtered signals. Statistical tests show that there is no significant difference between the average PSD of the HS-free original lung sounds and the TF-filtered signal for all frequency bands at both low and medium flow rates. It was found that the proposed method successfully removes HS from lung sound signals while preserving the original fundamental components of the lung sounds.

Adolescent↗
PubMed2006

Coronary reconstructive surgery versus coronary artery bypass grafting--a documentation gap.

OBJECTIVE: Over the last years, there has been a clear trend that an increasing number of patients are admitted for CABG with advanced disease, complex pathomorphological alterations and impaired left ventricular function. The necessity of performing extensive reconstructive coronary surgery rather than coronary bypass grafting, in its original sense, is not appropriately documented by the current version of the German Documentation System for Cardiac Surgery, nor in other national and international documentation systems. PATIENTS AND METHODS: 5821 consecutive, unselected patients underwent isolated CABG from 7/1995 through 12/2003 at a single institution. A closing date follow-up procedure up to 8 years postoperatively was performed with a completeness of 98.8%. RESULTS: The need for reconstructive surgery in terms of extended anastomoses with or without coronary endarterectomy has doubled in our patients since 1995 and is steadily increasing with 15.7 % (n=102) of these patients requiring such surgery in 2003. Current documentation does not allow any prediction of complex coronary morphology. The Kaplan-Meier survival curve reveals no substantial difference between patients with and without coronary reconstructive surgery up to 8 years after CABG. CONCLUSION: The increase of complexity in CABG procedures currently remains undetected, since preoperative imaging methods often fail to predict complex coronary morphology. Survival after coronary reconstructive surgery is comparable to that of "classical" CABG. Therefore, a standardized documentation is required to evaluate surgical results and to contribute to the improvement of medical decision-making which presupposes valid data.

Aged↗
PubMed2006

Bridge to operation with the GPIIb/IIIa inhibitor abciximab in high-risk coronary patients.

BACKGROUND: Glycoprotein-IIb/IIIa inhibitors are now frequently used in the cardiological treatment of high-risk coronary patients even if the patient is considered suitable for surgical intervention. However, there is no consensus whether GPIIb/IIIa inhibitors should be stopped before operation because of an increased risk of bleeding or if surgery should even be delayed until the anticoagulating effect subsides. METHODS: From June 2002 to August 2003 140 patients who had to undergo primary aorto-coronary bypass for ongoing myocardial ischemia were enrolled in the present study. The patients received either clopidogrel, aspirin and heparin or additionally abciximab until operation. RESULTS: Although the intraoperative need for blood products was higher in the abciximab group, there was no significant difference in postoperative blood loss. The hemodynamic situation of the abciximab patients after the operation was better compared to the other groups. 30-day mortality was not increased when compared to the elective control group (6.7 % vs. 6.1 %). CONCLUSION: The GPIIb/IIIa inhibitor abciximab can be safely used as a bridge to operation and results in a better hemodynamic outcome in high-risk coronary patients while reducing the incidence of major ischemic events.

Abciximab↗
PubMed2006

Midgut proteases of the cardamom shoot and capsule borer Conogethes punctiferalis (Lepidoptera: Pyralidae) and their interaction with aprotinin.

Protease inhibitors cause mortality in a range of insects, and transgenic plants expressing protease inhibitors have been protected against pest attack, particularly internal feeders that are not amenable to control by conventional means. A study of luminal proteases in Conogethes punctiferalis Guenée was performed to identify potential targets for proteinaceous biopesticides, such as protease inhibitors. The midgut protease profile of the gut lumen from C. punctiferalis was studied to determine the conditions for optimal protein hydrolysis. Optimum conditions for peptidase activity were found to be in 50 mm Tris-HCl, pH 10 containing 20 mm CaCl2; incubation for 30 min at 40 degrees C. Four synthetic substrates, i.e. benzoyl-arg-p-nitroanilide, benzoyl-tyr-p-nitroanilide, succinyl-ala-ala-pro-leu-p-nitroanilide (SAAPLpNA) and leu-p-nitroanilide were hydrolysed by C. punctiferalis gut proteases in Tris-HCl buffer pH 10. Trypsin and elastase-like chymotrypsin were the prominent digestive proteases, and age-related modulation of midgut proteases existed for trypsin, chymotrypsin, elastase-like chymotrypsin and leucine aminopeptidase. Serine protease inhibitors such as aprotinin, soybean trypsin inhibitor and phenylmethanesulfonyl fluoride inhibited peptidase activity. Some metal ions such as Ca(2+), Mg(2+), Pb(2+) and Co(2+) enhanced BApNA-ase activity whereas others like Mn(2+), Zn(2+), Cu(2+), Fe(2+) and Hg(2+) were inhibitory at 6 mm concentration. Trypsin and elastase-like chymotrypsin were significantly inhibited by 94% and 29%, respectively, by aprotinin (150 nm) under in vitro conditions. A possible incorporation of protease inhibitors into transgenic plants is discussed.

Animals↗
PubMed2006

Intraindividual, right-left comparison of topical methyl aminolaevulinate-photodynamic therapy and cryotherapy in subjects with actinic keratoses: a multicentre, randomized controlled study.

BACKGROUND: Actinic keratosis (AK), the most common premalignant skin condition, can represent a management challenge. Treatment should not only be effective, but also well tolerated and allow for good cosmesis on typical sun-exposed highly visible body sites. OBJECTIVES: The primary objective was to compare the lesion response and subject preference for topical methyl aminolaevulinate (MAL)-photodynamic therapy (PDT) vs. cryotherapy for the treatment of AK. METHODS: In this 24-week, multicentre, randomized, intraindividual (right-left) study, subjects received both one treatment session of MAL-PDT and a double freeze-thaw cryotherapy; the treatments were randomly allocated to either side of the face/scalp. Lesions with a noncomplete response were retreated after 12 weeks. The primary assessments were the subject's overall preference and lesion response at week 24. Secondary assessments included lesion response at week 12, cosmetic outcome, subject and investigator cosmetic outcome preference at week 24, and investigator overall preference at week 24. Skin discomfort and adverse events were also evaluated. RESULTS: In total, 119 subjects with 1,501 lesions were included in the study. At week 12, treatment with MAL-PDT resulted in a significantly larger rate of cured lesions relative to cryotherapy (percentage lesion reduction from baseline: 86.9% vs. 76.2%; P < 0.001). At week 24, both treatment groups showed a high rate of cured lesions (89.1% for MAL-PDT vs. 86.1% for cryotherapy; P = 0.20; 95% confidence interval: -1.62 to 7.67). Results for subject and investigator preferences as well as cosmetic outcome favoured MAL-PDT. Both treatment regimens were safe and well tolerated. CONCLUSIONS: The present study shows that, when treated with both MAL-PDT and cryotherapy, subjects significantly prefer MAL-PDT treatment for AK. MAL-PDT is an attractive treatment option for AK, with comparable efficacy and superior cosmetic outcomes compared with double freeze-thaw cryotherapy.

Aged↗
PubMed2006

Risk factors for voice problems in teachers.

In order to identify factors that are associated with voice problems and voice-related absenteeism in teachers, 1,878 questionnaires were analysed. The questionnaires inquired about personal data, voice complaints, voice-related absenteeism from work and conditions that may lead to voice complaints and absenteeism. Different factors play a role in the development and consolidation of voice problems. Physical and psycho-emotional factors appear to be the most important risk factors. Remarkably, voice load and environment seem to be less important as risk factors in the development and consolidation of voice complaints. Teachers who experienced voice problems during their training reported more voice problems during their career. The results of this study stress the importance of a multifactorial approach in the diagnosis and treatment of voice problems, whereby physical and psycho-emotional aspects should be considered as sensitive to the risk of developing voice problems. Moreover, this study shows the crucial importance of adequate voice training during the teacher training programme.

Absenteeism↗
PubMed2006

Epidemiology of voice problems in Dutch teachers.

In order to assess voice complaints and absence from work due to voice problems among teachers of primary and secondary education, as well as among a control group, 2,117 questionnaires were analysed. The total group consisted of 1,878 teachers and 239 controls. Female teachers more frequently reported voice complaints and absence from work due to voice problems than their male colleagues. No unequivocal relationship between age on the one hand and voice complaints and absence from work due to voice problems on the other hand was observed. Therefore, the percent of cases was corrected for gender but not for age. More than half of the teachers reported voice problems during their career and about one fifth had a history of absence from work due to voice problems. These numbers are relatively high compared to those of the controls with as well as to those without a vocally demanding profession. More than 20% of the teachers sought medical help or had been treated for a voice problem. Remarkably, more than 12% of the teachers had experienced voice problems during their training and this group reported significantly more voice complaints and absence from work due to voice problems in their career than the colleagues without voice problems during the training. The results of the Voice Handicap Index scores followed these trends. These findings point at voice problems during education as a risk factor for getting voice problems during the career. The results of this study clearly demonstrate that teaching is a high-risk profession for the development of voice problems, which is in accordance with other studies and support the contention that voice is a worldwide problem in the teaching profession. Furthermore, this study indicates the importance of voice care not only during training for the profession but also during the career.

Absenteeism↗
PubMed2006

Utility of the Type D Scale 16 and Voice Handicap Index to assist voice care in student teachers and teachers.

An epidemiological cross-sectional survey study was performed among female student teachers and teachers for primary education, using a general questionnaire, the Type D Scale 16 (DS16) and Voice Handicap Index (VHI). Type D personality is the combination of high 'negative affectivity' and high 'social inhibition', and the DS16 has been considered to be a reliable and valid measure of these two stable personality traits. The objectives of the study were to assess the VHI of type D subjects in comparison to non-type-D subjects, to explore the utility of the DS16 and the VHI to assess whether subjects with a type D personality were more handicapped due to their voice complaints, and whether they behaved differently in seeking voice care. It was investigated whether subjects of the type D group in comparison to the non-type-D group had a voice handicap even when they did not report voice complaints. The type D group did not report more voice complaints than the non-type-D group. However, the type D group had higher VHI scores compared to the non-type-D group. Furthermore, significantly more type D subjects had a VHI score greater than the 75th percentile than the non-type-D subjects, and they sought less voice care than the non-type-D subjects. Also among subjects who reported voice complaints, the type D group sought less care than the non-type-D group. Even among the subjects who did not report voice complaints, significantly more type D than non-type-D subjects had VHI scores higher than the 75th percentile. The findings indicated that type D subjects were apparently more bothered by their voice than the non-type-D subjects (high VHI scores); however, they did not report more voice complaints, and they also sought less voice care. The DS16 used along with the VHI was useful to identify subjects of the type D trait with a voice handicap. This enables specific voice care, encompassing not only physical, but also psychosocial aspects of vocal health.

Adult↗
PubMed2006

Voice complaints, risk factors for voice problems and history of voice problems in relation to puberty in female student teachers.

The aim of the study was to estimate voice complaints, risk factors for voice complaints and history of voice problems in student teachers before they embarked on their professional teaching career. A cross-sectional questionnaire survey was performed among female student teachers. The response rate was 72% and 457 questionnaires were analyzed. Voice complaints at the moment and/or during the past year were reported by 39.6% subjects. Subjects with voice complaints had significantly higher VHI scores than subjects without voice complaints. In comparison to subjects without voice complaints, overall, subjects with voice complaints reported more frequently that vocal loading factors, physical factors, environmental factors and psychological factors had a negative influence on their voice. Subjects with voice complaints reported more frequently a history of voice complaints during puberty and before puberty in comparison to subjects without voice complaints. Voice complaints in student teachers apparently had a multifactorial genesis and with roots during puberty or before puberty. Logistic regression analysis revealed that intensive voice use, emotions and history of voice complaints during puberty were the most discriminating set of risk factors for voice complaints. Subjects with voice complaints in comparison to those without voice complaints reported more frequently that they would develop a voice problem due to future teaching and that future teaching would have a negative influence on their voice. Around three quarters of subjects with and without voice complaints reported that attention paid to their voice during their training was sufficient. However, subjects with voice complaints were observed to report the need for a refresher course on voice use more frequently than those without voice complaints. The findings call for more intensive voice training for student teachers to cope with the vocal, physical and psychological demands of the teaching profession. Authorities should take responsibility to monitor and improve working conditions of student teachers and teachers.

Adolescent↗
PubMed2005

A comparative study of voice complaints and risk factors for voice complaints in female student teachers and practicing teachers early in their career.

A cross-sectional questionnaire survey was performed to compare female student teachers (454 subjects; 1st to 4th year of training) and practicing teachers (82 female teachers; 1st to 4th year of teaching career) of primary education early in their career, with regard to risk factors perceived to be a negative influence on the voice, and the relative risk of the given risk factors for voice complaints. This enables the observation of whether there is a sudden increase or difference in the perceived risk factors after starting a professional teaching career. Additionally, the existence of a history of voice problems during training was questioned among the teachers. Teachers with voice complaints compared to teachers without voice complaints reported a history of voice complaints during their training (P =0.013). Teachers compared to student teachers reported more voice complaints at the moment and/or during the past year (P =0.002). The following data were obtained from student teachers and teachers reporting voice complaints. Only around a third of the subjects of both groups sought voice care (P =0.286-0.893). Risk factors were estimated in relation to voice complaints. Student teachers reported less frequently than teachers that stress (P =0.014), work pressure (P =0.003) and the composition of the class (P =0.013) have a negative influence on their voice. Student teachers reported less frequently than teachers that the number of people they communicate with (P <0.001) and the deterioration of their general physical condition (P =0.010) have a negative influence on their voice. Student teachers reported more frequently than teachers that environmental irritants (P <0.001) and humidity (P =0.020) of the classroom have a negative influence on their voice. Student teachers more than teachers were of the opinion that the attention paid to the voice during their training was sufficient (P <0.001). To test whether professional status (student teacher versus teacher) is an effect modifier for the risk factors, odds ratios (OR) were compared between the group of teachers and of student teachers (total group with and without voice complaints) to search for interactions between the risk factors and professional status. There is a significant difference in the pattern of risk factors for student teachers and teachers (P =0.010). There is an indication that vocal loading factors and environmental factors are more influential in student teachers and that there is a tendency for psycho-emotional factors to be more influential for teachers early in their career.

Adolescent↗
PubMed2005

Absence of a specific radiation signature in post-Chernobyl thyroid cancers.

Thyroid cancers have been the main medical consequence of the Chernobyl accident. On the basis of their pathological features and of the fact that a large proportion of them demonstrate RET-PTC translocations, these cancers are considered as similar to classical sporadic papillary carcinomas, although molecular alterations differ between both tumours. We analysed gene expression in post-Chernobyl cancers, sporadic papillary carcinomas and compared to autonomous adenomas used as controls. Unsupervised clustering of these data did not distinguish between the cancers, but separates both cancers from adenomas. No gene signature separating sporadic from post-Chernobyl PTC (chPTC) could be found using supervised and unsupervised classification methods although such a signature is demonstrated for cancers and adenomas. Furthermore, we demonstrate that pooled RNA from sporadic and chPTC are as strongly correlated as two independent sporadic PTC pools, one from Europe, one from the US involving patients not exposed to Chernobyl radiations. This result relies on cDNA and Affymetrix microarrays. Thus, platform-specific artifacts are controlled for. Our findings suggest the absence of a radiation fingerprint in the chPTC and support the concept that post-Chernobyl cancer data, for which the cancer-causing event and its date are known, are a unique source of information to study naturally occurring papillary carcinomas.

Adenoma↗