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Biomedical subjects

K Martin

Publications and source records attributed to K Martin.

At least 19 recordsLinked to original sources
PubMed2006

[Cost of illness studies as a basis for decision making].

Definitions and methods for cost of illness studies are explained: costs, direct costs, indirect costs, intangible costs, the human capital method and the willingness to pay approach. Devaluing the long-term health benefits from prevention by constant discount rates is questioned. The development and the state of the art of cost of illness studies at a national level in Germany are discussed. As an example the newly developed cost of illness study of the Federal Statistical Office with direct and indirect costs of circulatory diseases is presented. Reasons for the benefit of cost of illness studies for decision making are given in the context of costs of illness and aging.

Cost of Illness↗
PubMed2006

Definition, evaluation, and classification of renal osteodystrophy: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO).

Disturbances in mineral and bone metabolism are prevalent in chronic kidney disease (CKD) and are an important cause of morbidity, decreased quality of life, and extraskeletal calcification that have been associated with increased cardiovascular mortality. These disturbances have traditionally been termed renal osteodystrophy and classified based on bone biopsy. Kidney Disease: Improving Global Outcomes (KDIGO) sponsored a Controversies Conference on Renal Osteodystrophy to (1) develop a clear, clinically relevant, and internationally acceptable definition and classification system, (2) develop a consensus for bone biopsy evaluation and classification, and (3) evaluate laboratory and imaging markers for the clinical assessment of patients with CKD. It is recommended that (1) the term renal osteodystrophy be used exclusively to define alterations in bone morphology associated with CKD, which can be further assessed by histomorphometry, and the results reported based on a unified classification system that includes parameters of turnover, mineralization, and volume, and (2) the term CKD-Mineral and Bone Disorder (CKD-MBD) be used to describe a broader clinical syndrome that develops as a systemic disorder of mineral and bone metabolism due to CKD, which is manifested by abnormalities in bone and mineral metabolism and/or extra-skeletal calcification. The international adoption of these recommendations will greatly enhance communication, facilitate clinical decision-making, and promote the evolution of evidence-based clinical practice guidelines worldwide.

Chronic Kidney Disease-Mineral and Bone Disorder↗
PubMed2006

The Sony Ericsson WTA Tour 10 year age eligibility and professional development review.

Concerns have long existed over the participation of adolescent athletes in professional sports. In 2004, the Sony Ericsson WTA Tour (WTA Tour) commissioned a Professional Development Advisory Panel (PDAP) to evaluate the WTA Tour's age eligibility rule (AER) and professional development programmes (PDPs) for female tennis players since their inception in 1995. More than 75% of the 628 respondents supported the principles of the AER, and 90% indicated a need for PDPs. Statistical analysis of WTA Tour players' careers found that premature retirements (players leaving the Tour at or before age 21) decreased significantly from 7% before the AER to less than 1% afterward, and median career length increased by 43%. The PDAP recommends that the WTA Tour continues a phased-in, developmentally appropriate AER, enhances the PDPs, and works with other sport governing bodies to coordinate rules and programmes at earlier ages to aid the transition of adolescents into adult sports.

Adolescent↗
PubMed2004

MEG response to median nerve stimulation correlates with recovery of sensory and motor function after stroke.

OBJECTIVE: Hemiparesis due to damage by stroke in primary motor cortex (MI) or its underlying projections presents a problem for functional neuroimaging technologies that attempt to evaluate the neurophysiological basis for restoration of motor function. Traditional assessments of MI function require patients to move their fingers, hands, or limbs, which can be either impossible or markedly compromised after stroke. We recently demonstrated in normal subjects that magnetoencephalography (MEG), a non-invasive neuromagnetic functional imaging technique, detects neuronal response elicited by electrical median nerve stimulation in MI, as well as primary somatosensory cortex (SI). In the present study, we used the MEG response from median nerve stimulation to investigate the recovery of primary motor and somatosensory in acute ischemic stroke patients. METHODS: Twelve patients with unilateral ischemic strokes that affected sensorimotor functions of their hand were studied in the acute stage (4.4+/-1.2 days, mean+/-SD) and during a 1-month follow-up (38.6+/-5.6 days, except for one patient's follow-up done 6 month after stroke). RESULTS: Among the multiple cortical sources localized after median nerve stimulation, one source localized to SI and another localized to the vicinity of MI. Changes in the source strengths of the first component post-stimulus of MI and SI correlated with the extent of recovery of sensorimotor functions as determined by neurological exams. CONCLUSIONS: This study provides a novel way of indirectly assessing MI function using MEG during the acute stroke phase, when many patients often cannot perform motor tasks due to paralysis.

Adult↗
PubMed2004

[Reversible postpartum cerebral angiopathy associated with bromocriptine therapy].

BACKGROUND: Postpartum is known to be an important risk factor for stroke. Bromocriptine may induce cerebral angiopathy. CASE DESCRIPTION: We report the case of a 26-year-old postpartum woman who presented with headaches, seizures, hypertension and acute renal failure eight days after the beginning of a treatment with bromocriptine prescribed for lactation suppression. Brain MRI and MR angiogram excluded cortical vein thrombosis and revealed multiple abnormal areas of increased signal in the cortex with segmental arterial narrowings of intracranial vasculitis. The patient completely recovered within one week after drug withdrawal. Biological and radiological abnormalities were also reversible. Following the chronology bromocriptine was most likely responsible for this adverse cerebral and systemic event. CONCLUSION: Clinicians should be aware of bromocripine-related postpartum cerebral angiopathy, a rarely described but serious complication of bromocriptine used to prevent postpartum breast engorgement.

Adult↗
PubMed2004

An update of recent evidence of the relationship between objective and self-report measures of the physical environment and physical activity behaviours.

The physical environment has the potential to influence the physical behaviours of large numbers of people; hence creating supportive environments has the potential to increase physical activity (PA). During the last decade, there has been growing interest in how the physical environment shapes PA behaviour. This area of research is important given that levels of PA participation are declining globally. Literature was reviewed that examined the association between physical environmental attributes and PA behaviours. The environmental attributes were grouped into four categories based on a conceptual framework of environmental factors that might influence PA and included functionality, safety, aesthetics and destinations. Positive associations were found between both perceived and objectively measured environmental factors and PA behaviour. The availability, accessibility and convenience of destinations and facilities, as well as the general functionality of the neighbourhood (eg, the presence of sidewalks, traffic conditions) and aesthetics were positively associated with various levels of PA. The review highlights the need for future studies: to examine behaviour-specific environmental attributes, to collect objectively-measured environmental data and to include both objective and perceived environmental data in the same studies, and to adopt prospective study designs to allow causal relationships to be established.

Environment↗
PubMed2004

Commonalities and differences among vectorized beamformers in electromagnetic source imaging.

A number of beamformers have been introduced to localize neuronal activity using magnetoencephalography (MEG) and electroencephalography (EEG). However, currently available information about the major aspects of existing beamformers is incomplete. In the present study, detailed analyses are performed to study the commonalities and differences among vectorized versions of existing beamformers in both theory and practice. In addition, a novel beamformer based on higher-order covariance analysis is introduced. Theoretical formulas are provided on all major aspects of each beamformer; to examine their performance, computer simulations with different levels of correlation and signal-to-noise ratio are studied. Then, an empirical data set of human MEG median-nerve responses with a large number of neuronal generators is analyzed using the different beamformers. The results show substantial differences among existing MEG/EEG beamformers in their ways of describing the spatial map of neuronal activity. Differences in performance are observed among existing beamformers in terms of their spatial resolution, false-positive background activity, and robustness to highly correlated signals. Superior performance is obtained using our novel beamformer with higher-order covariance analysis in simulated data. Excellent agreement is also found between the results of our beamformer and the known neurophysiology of the median-nerve MEG response.

Brain↗
PubMed2004

Patterns of risperidone prescription: a utilization study in south-west France.

OBJECTIVE: To describe the patterns of prescriptions associated with risperidone in naturalistic clinical practice. METHOD: We analysed 500 prescription forms randomly selected from the social security insurance database in Aquitaine (south-west France). RESULTS: The prevalence of co-prescription was 42.5% for antidepressants, 46.4% for benzodiazepines, 26.6% for other neuroleptics, 21.8% for mood stabilizers and 19% for anticholinergic drugs. The high prevalence of co-prescribed antidepressants (59.3% Selective Serotonin Reuptake Inhibitors) may be explained by the frequent comorbidity of mood disorders in schizophrenia, and by the fact that risperidone was prescribed in naturalistic conditions in disorders other than schizophrenia. CONCLUSION: The high level of concomitant drug prescription in patients treated with risperidone illustrates the gap between clinical trials and utilization in naturalistic settings. The association antidepressant-risperidone has been insufficiently studied for efficacy or safety, and has to be explored further from both a pharmacological and clinical point of view.

Adolescent↗
PubMed2004

Symptomatic bone disorders in HIV-infected patients: incidence in the Aquitaine cohort (1999-2002).

BACKGROUND: Since the inception of highly active antiretroviral therapy (HAART), mortality among HIV-infected patients has decreased, but this has been accompanied by the appearance of several complications. OBJECTIVES: To estimate the incidence of symptomatic bone disorders in HIV-infected patients of the Aquitaine cohort (from south-west France) for the period 1999-2002, and to describe cases. METHODS: We retrospectively studied the records of 2700 patients of the Aquitaine cohort, which was derived from a hospital-based surveillance system of HIV infection in France. All cases of symptomatic bone disorders diagnosed from 1 January 1999 to 30 June 2002 were reviewed. RESULTS: Fourteen cases of bone disorders were diagnosed, eight cases of aseptic osteonecrosis and six cases of severe osteoporosis, representing incidences of 0.3/1000 patient-years [95% confidence interval (CI): 0.14-0.62] and 0.22/1000 patient-years (95% CI: 0.09-0.52), respectively. All patients with aseptic osteonecrosis were male, while all but one with osteoporosis were female. The ages of patients ranged from 36 to 54 years for osteonecrosis and from 39 to 50 for severe osteoporosis. At the time of clinical diagnosis, all patients were treated with nucleoside reverse transcriptase inhibitors (duration of treatment ranging from 19 to 123 months for osteonecrosis and from 46 to 132 months for severe osteoporosis). Ten patients were treated with nonnucleoside reverse transcriptase inhibitors [duration of treatment ranging from 6 to 31 months for osteonecrosis (n=6) and from 4 to 29 months for severe osteoporosis (n=4)]. Thirteen patients were treated with protease inhibitors [duration of treatment ranging from 12 to 62 months for osteonecrosis (n=8) and from 3 to 44 months for severe osteoporosis (n=5)]. All osteonecrosis and five osteoporosis patients had at least one known risk factor or comorbidity associated with the bone disorder occurrence. CONCLUSIONS: In our study, the aetiology of clinical bone disorders seemed to be multifactorial, as almost all the patients had at least one possible risk factor in addition to HAART exposure.

Adult↗
PubMed2003

Response to combination therapy with interferon alfa-2a and ribavirin in chronic hepatitis C according to a TNF-alpha promoter polymorphism.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) is involved in the pathogenesis of chronic active hepatitis C. Polymorphisms in the promoter region of the TNF-alpha gene can alter the TNF-alpha expression and modify the host immune response. The present study aimed at the correlation of the G308A TNF-alpha polymorphism with the response to antiviral combination therapy in chronic hepatitis C. PATIENTS AND METHODS: 62 patients with HCV and 119 healthy unrelated controls were genotyped for the G308A TNF-alpha promoter polymorphism. The patients received 3 x 3 million units of interferon alfa-2a and 1,000-1,200 mg ribavirin daily according to their body weight. A response was defined as absence of HCV-RNA and normalization of S-ALT after 6 months of combination therapy. RESULTS: With respect to the allele and genotype frequency, a significant difference was not observed between controls and patients with chronic hepatitis C. Furthermore, such a difference was also not observed if responders and non-responders to antiviral therapy were compared. CONCLUSIONS: The promoter polymorphism of the TNF-alpha gene investigated herein is equally distributed in healthy individuals and patients with hepatitis C and does not seem to predict the response to therapy with interferon alfa-2a and ribavirin.

Adult↗
PubMed2003

The Delta 32 mutation of the chemokine-receptor 5 gene neither is correlated with chronic hepatitis C nor does it predict response to therapy with interferon-alpha and ribavirin.

Unlike in HIV, homozygosity for a 32-bp deletion (Delta 32) of the chemokine receptor 5 (CCR5) gene was recently described in increased frequency in patients with chronic hepatitis C (HCV). Thus, it was speculated that this mutation might be relevant for disease susceptibility and influence the response to antiviral therapy. The present study sought to confirm the association between HCV and the Delta 32 mutation of the CCR5 gene and to correlate it with the response to therapy with interferon-alpha-2a and ribavirin. Sixty-two patients with HCV and 119 healthy unrelated controls were genotyped for the Delta 32 mutation. For the correlation between the Delta 32 mutation and response to therapy, only patients (n = 59) who completed 6 months of combination therapy as part of a prospective study were evaluated. The Delta 32 mutation was not observed in increased frequency in HCV. Furthermore, a significant difference of the HCV load or aminotransferase concentrations was not observed in carriers versus noncarriers of the Delta 32 mutation. After stratification for potentially confounding factors such as gender or HCV genotype, a significant difference was also not detected with respect to treatment outcome. These observations argue strongly against a role of CCR5 for susceptibility to HCV infection or response to combination therapy.

Antiviral Agents↗
PubMed2003

A palmitylated peptide derived from the glycoprotein Ib beta cytoplasmic tail inhibits platelet activation.

The platelet receptor GPIb/IX/V mediates a crucial role in hemostasis, yet the signaling mechanisms involved are incompletely understood. The complex consists of four polypeptides GPIb alpha, GPIb beta, GPIX and GPV. We identified an amino acid sequence in the cytoplasmic tail of the GPIb beta subunit between residues R151 and A161 that is highly conserved across species and hypothesized that it has functional importance. To target this motif, we synthesized a corresponding cell-permeable palmitylated peptide (Pal-RRLRARARARA) and investigated its effect on platelet function. Pal-RRLRARARARA completely inhibited low dose thrombin- and ristocetin-induced aggregation in washed platelets but only partially inhibited collagen- and U46619-induced aggregation. Thromboxane production in platelets stimulated with thrombin was significantly reduced by Pal-RRLRARARARA compared with collagen. Activation of the integrin alpha IIb beta 3 in response to thrombin was significantly reduced when platelets were preincubated with Pal-RRLRARARARA. The adhesion of washed platelets to von Willebrand factor (VWF) under static conditions was significantly reduced by Pal-RRLRARARARA. Under conditions of high shear, the velocity of platelets rolling on VWF was significantly increased when platelets are preincubated with Pal-RRLRARARARA. This study defines a novel function for the RRLRARARARA motif of GPIb beta in platelet activation.

Blood Platelets↗
PubMed2002

Chronic substance P (NK1) receptor antagonist and conventional antidepressant treatment increases burst firing of monoamine neurones in the locus coeruleus.

The mechanism of action of conventional antidepressants (e.g. imipramine) has been linked to modulation of central monoamine systems. Substance P (NK1) receptor antagonists may have antidepressant and anxiolytic effects in patients with major depressive disorder and high anxiety but, unlike conventional antidepressants, are independent of activity at monoamine reuptake sites, transporters, receptors, or monoamine oxidase. To investigate the possibility that substance P receptor antagonists influence central monoamine systems indirectly, we have compared the effects of chronic administration of imipramine with that of the substance P receptor antagonist L-760735 on the spontaneous firing activity of locus coeruleus neurones. Electrophysiological recordings were made from brain slices prepared from guinea-pigs that had been dosed orally every day for 4 weeks with either L-760735 (3 mg/kg), imipramine (10 mg/kg), or vehicle (water), or naive animals. Chronic, but not acute, treatment with the substance P receptor antagonist L-760735, induced burst firing of neurones in the locus coeruleus. This effect resembles that of the conventional antidepressant imipramine. However, their effects are dissociable since, in contrast to chronic imipramine treatment, chronic L-760735 treatment does not cause functional desensitisation of somatic alpha2 adrenoceptors. The mechanism by which chronic substance P receptor antagonist or conventional antidepressant treatment influences the pattern of firing activity of norepinephrine neurones remains to be elucidated. However, an indirect action in the periphery or distant brain nuclei has been excluded by the use of the in vitro slice preparation, suggesting a local site of action in the locus coeruleus.

Action Potentials↗
PubMed2002

[26-year-old female patient with elevated liver enzymes].

A 26-year-old woman presented with elevated liver enzymes, which were diagnosed two months ago. Examination revealed mild proximal muscle weakness, though the patient herself did not realise any impairment. The abdominal ultrasound and the histology of the liver remained unsuspicious. Muscle biopsy showed vacuolar degeneration, which could be ultrastructurally identified as large deposits of membrane-bound glycogen. The morphological findings prompted biochemical investigations which showed an excess of muscle glycogen. Acid maltase activity was reduced to < 10 % of normal, leading together with the clinical findings to the diagnosis of glycogenosis type II (Pompe's disease) of the adult type. Because of the modest impairment of the patient and the limited therapeutic possibilities, the patient remained thus untreated for.

Adult↗
PubMed2002

K-ras mutations in sera of patients with colorectal neoplasias and long-standing inflammatory bowel disease.

BACKGROUND: About 50% of colorectal carcinomas and adenomas display K-ras mutations, which have also been described in stool or colonic lavage fluid. Moreover, the presence of K-ras mutations in plasma samples originating from patients with colorectal cancer has been reported recently. METHODS: DNA was extracted from sera of 16 patients with colorectal carcinomas, 6 with large adenomas, 3 with Crohn disease and 4 with ulcerative colitis. Sera of 20 healthy blood donors served as negative controls. K-ras mutations at the first or second position of codon 12 were detected by an enriched RFLP-PCR method and confirmed by sequencing. RESULTS: Mutations were found in sera of 5 patients with colorectal carcinomas (31%) and 2 patients with long-standing ulcerative pancolitis (50%), but not in patients with adenomas, Crohn disease or the controls. CONCLUSIONS: K-ras mutations can be detected in serum samples from patients with manifest colorectal cancer and in patients who display an increased risk for malignant transformation of the colonic mucosa. This observation may have clinical application concerning noninvasive surveillance of these patients. Because of the low sensitivity of this approach it may be useful to combine it with other molecular markers.

Adenocarcinoma↗