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Biomedical subjects

S Martin

Publications and source records attributed to S Martin.

At least 55 records · Page 3Linked to original sources

DNA sequence and analysis of human chromosome 9.

Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.

Base Composition↗

Dexterity enhancement with robotic surgery.

BACKGROUND: The aim of this study was to quantify the extent of dexterity enhancement in robotic surgery as compared to laparoscopic surgery. METHODS: Ten surgeons with varying laparoscopic suturing experience were asked to place three sutures on a suture pad. The sutures were placed laparoscopically, robotically with 2-D vision and robotically with 3-D vision. The da Vinci systems Application Programming Interface (API) was used for positional data. A validated motion analysis system was used for data retrieval for the laparoscopic task. Custom software was developed for data analysis. RESULTS: Compared to laparoscopic suturing, when the task was undertaken robotically with 2-D vision there was a 20% reduction in the time taken but this was not significant (p = 0.07). There was a 55% reduction in the path traveled by the right hand (p = 0.01) and a 45% reduction in the path traveled by the left hand (p = 0.008). When the task was undertaken robotically with 3-D vision, there was a 40% reduction in the time taken (p = 0.01). There was a 70% reduction in the path traveled by right hand (p = 0.008) and a 55% reduction by the left hand (p = 0.08). CONCLUSIONS: The presence of wristed instrumentation, tremor abolition, and motion scaling enhance dexterity by nearly 50% as compared to laparoscopic surgery. 3-D vision enhances dexterity by a further 10-15%. In addition, the presence of 3-D vision results in a 93% reduction in skills-based errors.

Clinical Competence↗

The DNA sequence and analysis of human chromosome 13.

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.

Chromosome Mapping↗

The benefits of stereoscopic vision in robotic-assisted performance on bench models.

BACKGROUND: Previous studies have failed to establish clear advantages for the use of stereoscopic visualization systems in minimal-access surgery. The aim of this study was to objectively assess whether stereoscopic visualization improves performance on bench models using the da Vinci robotic system. METHODS: Eleven surgeons carried out a series of four tasks. Positional data streamed from the da Vinci system was analyzed by means of a previously validated custom-designed software-package. An independent blinded observer scored errors. Statistical analysis included the Wilcoxon signed rank test. A p < 0.05 was deemed significant. RESULTS: We found significant improvements in all tasks and for all parameters (p < 0.05). In addition, a significantly lower number of errors was scored using the stereoscopic mode as compared to the standard two-dimensional image (p < 0.001). CONCLUSION: Robotic-assisted performance on bench models is more efficient and accurate using stereoscopic visualization.

Data Display↗

Qualitative and quantitative analysis of the learning curve of a simulated surgical task on the da Vinci system.

BACKGROUND: Robotic telemanipulation systems provide solutions to the problems of less dexterity and visual constraints of minimally invasive surgery (MIS). However, their influence over surgeons' dexterity and learning curve needs to be assessed. We present motion analysis as an objective method to measure performance and learning progress.METHODS. Thirteen surgeons completed five synthetic small bowel anastomoses using the da Vinci system. Objective Structured Assessment of Technical Skills (OSATS) allowed qualitative analysis. Quantitative analysis used API software of the system to retrieve real-time robotic signal data of time, path length, and number of movements. Wilcoxon signed ranks test was used for statistical analysis. A p value <0.05 was considered significant.RESULTS. OSATS global scores were 18.6 points for the first attempt and 26 for the fifth attempt ( p < 0.02, Cronbach's alpha = 0.894). Paired data of motion analysis for attempts 1 vs 5 showed significant change: time taken 3507 sec and 2287 sec ( p < 0.008), total number of movements 2411 and 1387 ( p = 0.01), total path length 21,630 cm and 13,941 cm ( p = 0.01).CONCLUSIONS. A rapid learning curve to a competent level using the da Vinci system is possible aided by the system's intuitive motion. Motion analysis is a useful tool to measure performance in the da Vinci system compared to OSATS and time alone.

Anastomosis, Surgical↗

Prospective documentation and analysis of the pre- and early clinical management in severe head injury in southern Bavaria at a population based level.

Treatment of patients suffering from severe head injury is so far restricted to general procedures, whereas specific pharmacological agents of neuroprotection including hypothermia have not been found to improve the outcome in clinical trials. Albeit effective, symptomatic measures of the preclinical rescue of patients (i.e. stabilization or reestablishment of the circulatory and respiratory system) or of the early clinical care (e.g. prompt diagnosis and treatment of an intracranial space occupying mass, maintenance of a competent circulatory and respiratory system, and others) by and large constitute the current treatment based on considerable organizational and logistical efforts. These and other components of the head injury treatment are certainly worthwhile of a systematic analysis as to their efficacy or remaining deficiencies, respectively. Deficits could be associated with delays of providing preclinical rescue procedures (e.g. until intubation of the patient or administration of fluid). Delays could also be associated in the hospital with the diagnostic establishment of intracranial lesions requiring prompt neurosurgical intervention. By support of the Federal Ministry of Education and Research and under the auspices of the Forschungsverbund Neurotraumatology, University of Munich, a prospective system analysis was carried out on major aspects of the pre- and early clinical management at a population based level in patients with traumatic brain injury. Documentation of pertinent data was made from August 1998 to July 1999 covering a catchment area of Southern Bavaria (5.6 mio inhabitants). Altogether 528 cases identified to suffer from severe head injury (GCS < or = 8 or deteriorating to that level within 48 hrs) were enrolled following admission to the hospital and establishment of the diagnosis. Further, patients dying on the scene or during transport to the hospital were also documented, particularly as to the frequency of severe head injury as underlying cause of mortality. The analysis included also cases with additional peripheral trauma (polytrauma). The efficacy of the logistics and organization of the management was studied by documentation of prognosis-relevant time intervals, as for example until arrival of the rescue squad at the scene of an accident, until intubation and administration of fluid, or upon hospital admission until establishment of the CT-diagnosis and commencement of surgery or transfer to the intensive care unit, respectively. The severity of cases studied in the present analysis is evident from a mortality of far above 40% of cases admitted to the hospital, which was increased by about 20% when including prehospital mortality. The outcome data notwithstanding, the emerging results demonstrate a high efficacy of the pre- and early clinical management, as indicated by a prompt arrival of the rescue squad at the scene, a competent prehospital and early clinical management and care, indicative of a low rate of avoidable complications. It is tentatively concluded on the basis of these findings that the patient prognosis is increasingly determined by the manifestations of primary brain damage vs. the development of secondary complications.

Craniocerebral Trauma↗

[Ocular involvement in systemic Loa-Loa filariasis. Case report and review of the literature].

BACKGROUND: Within the last few years there is more and more evidence for nonspecific ocular symptoms caused by "exotic" pathogens. We herewith report another case of such an infection to underline the increasing importance and diagnostic relevance even of rare diseases. PATIENT: A 35-year-old female German patient presented with recurrent left retrobulbar "feeling of pressure" after a 6-month-stay in Central Africa 5 years ago. In addition, she reported on repeated swelling of the skin and joints of her hands and arms. Multiple ophthalmologic and rheumatologic investigations had been carried out without diagnostic results. Her ophthalmologist referred her with the presumed diagnosis of a subconjunctival worm. RESULTS: Slit-lamp biomicroscopy confirmed the original suspicion, and after topical anesthesia a female Loa-Loa worm was easily removed with forceps through a conjunctival incision. The general examination showed symptoms of systemic infection (calabar swelling, eosinophilia). Classification and initiation of treatment with diethylcarbamazine and mebendazole were carried out by the University Institute of Parasitology. CONCLUSION: Loa-Loa is a parasitic infection endemic in the tropical rain forests of Western, Central, and Eastern Africa. It is transmitted by the Chrysops fly. An increasing number of oculosystemic infections in non-African patients with Loa-Loa are being published. Therefore, any patient with an unclassifiable eye affection should also be investigated for those rare pathogens.

Adult↗

[Effect of smoking on the effectiveness of antimalarial drugs for cutaneous lesions of patients with lupus: assessment in a prospective study].

PURPOSE: Smoking has been involved in the failure of antimalarial therapy in patient with chronic or subacute erythematosus lupus. METHODS: We report a prospective study of 26 patients with chronic, subacute or systemic erythematosus lupus who were treated with antimalarials. Several variables including smoking are compared in responders and non-responders. RESULTS: Despite the reduced number of patients study that does not permit to allow significative results, it seems that among responders and non-responders, in other respects comparables, there is no difference in the presence of smoking, its quantity or its duration. CONCLUSION: The significance of molecular interactions between some components of tobacco and antimalarials have still to be established.

Adult↗

Childhood amblyopia treatment: psychosocial implications for patients and primary carers.

PURPOSE: To investigate the psychosocial impact of amblyopia therapy on children and their carers. METHOD: The study was prospective and incorporated a repeated-measures design. A total of 59 carers were classified into occluded (n=31) or nonoccluded group (n=28). A questionnaire consisting of the Perceived Stress Index (PSI) and the Perceived Psychosocial Questionnaire (PPQ) was used to measure carer's perception of stress and psychosocial well-being of the child respectively prior to and following commencement of treatment. Parametric and nonparametric tests were used to analyse the data. RESULTS: No significant difference in carer's stress (P>0.05) and child's psychosocial well-being (P>0.05) was observed between occluded and nonoccluded groups. Within occluded group, carer's stress (P>0.05) and child's psychosocial well-being (P>0.05) did not differ significantly before and following commencement of treatment. Within the occluded group, carers felt more negative towards their child following onset of glasses therapy (P<0.01) and became more positive when occlusion was introduced in the subsequent follow-up (P<0.01). CONCLUSIONS: When compared to carers in the nonoccluded group, those with children undergoing occlusion therapy did not experience significantly more stress or perceived their child as exhibiting less psychosocial well-being. Within the occluded group, carers' stress level and child's psychosocial well-being did not significantly change following onset of occlusion therapy. Carers felt temporarily more negative towards the child following onset of treatment with glasses. In this study, there is no evidence to indicate that occlusion therapy has negative psychosocial impact on carers and children alike.

Adult↗

Influence of HFE gene polymorphism on the progression and treatment of chronic hepatitis C.

We analysed liver histology findings in a large cohort of patients with chronic hepatitis C and in roughly half of them their response to interferon-alpha-based on iron parameters and HFE status. Histological activity and virological response to antiviral therapy (n = 146) were analysed in 273 immunocompetent and nonalcoholic patients with chronic hepatitis C, in terms of serum iron load, intrahepatic iron load (n = 110) and HFE mutations. Patients who were heterozygous for the C282Y and H63D mutations exhibited higher iron serum parameters than subjects without these mutations. The intrahepatic iron load was higher in H63D patients only. No association was observed between HFE mutations and histological activity. Increased iron parameters were associated with liver disease severity by univariate analysis only. Genotype 1 and ferritinaemia were associated with a poor response to antiviral therapy, whereas the H63D mutation emerged as a positive predictive factor for end of treatment and sustained antiviral response. Therefore, in chronic hepatitis C patients serum and intrahepatic iron levels were weakly correlated with histological activity, while HFE mutations were not. As for the response to interferon-alpha, elevated ferritinaemia constituted a negative predictive factor whereas the H63D mutation was a positive one. The H63D mutation might form part of an immunogenetic profile influencing the response to interferon therapy.

Adolescent↗

Identification of pancreatic exocrinopathy in non-obese diabetic mice by gene subtraction analysis.

Type 1 diabetes is an immune-mediated disease with pancreatic infiltration and subsequent beta cell destruction. In this study pancreatic exocrinopathy in non-obese diabetic mice (NOD) was identified using gene subtraction methods (SSH) and macroarray analysis. Female NOD mice were treated with cyclophosphamide for acceleration and synchronization of the disease process at 70 d of age and analysed 10 d later, before the onset of overt diabetes. Extraction of total RNA of pancreas was followed by subtraction using the SSH technique. Pools of cDNA were generated using total RNA from treated and untreated NOD mice. Subtraction of cDNA pools of cyclophosphamide treated mice from cDNA pools of untreated mice resulted in a cDNA library, from which 480 clones were randomly selected. The clones were hybridized against labelled cDNA-probes generated from cyclophosphamide-treated and control NOD mice. Fifty-three clones (11 %) revealed at least twofold differential gene expression after cyclophosphamide treatment. Three of the downregulated genes (amylase, carboxypeptidase and preprotrypsin) were selected for evaluation of macroarray data by quantitative real-time PCR. Analysis of real-time PCR data confirmed suppression of gene expression with highest fold change for amylase (4.68-fold) followed by carboxypeptidase (2.79-fold) and preprotrypsin (2.14-fold). These results lead to the conclusion that inflammation in this animal model of type 1 diabetes is not restricted to pancreatic islets and that subtraction followed by macroarray analysis is capable of identifying genes responsible associated with disease progression.

Amylases↗

Robot-assisted laparoscopic adrenalectomy: preliminary UK results.

OBJECTIVE: To describe the results of our first two cases of laparoscopic adrenalectomy using the da Vinci surgical system (Intuitive Surgical, Inc., Mountain View, CA, USA). PATIENTS AND METHODS: Amongst 75 robot-assisted procedures performed at our institution, two patients underwent robot-assisted laparoscopic adrenalectomy. The set-up time, procedure time, hospital stay, complications and outcomes were recorded. RESULTS: Both operations were completed successfully using the robot; the mean (range) set-up time was 31 (25-37) min and mean procedure time 118.5 (107-130) min. One patient had a postoperative pulmonary embolus and was discharged 5 days after surgery; the second patient was discharged after 3 days. There were no intraoperative complications; both patients were well at the 1-year follow-up. CONCLUSIONS: Robot-assisted laparoscopic adrenalectomy is technically feasible and can be conducted efficiently and safely with the da Vinci surgical system.

Adenoma↗

Use of "Near Middle East Antivenom" to treat African bush viper envenomation.

Venom from an African bush viper is primarily hemotoxic and potentially life threatening. Existing, commercialy available antivenoms may not neutralize venom of this genus. A 25-y-old male was brought to the emergency room diaphoretic and hypotensive (70/40 mmHg) after a bite from a pet African bush viper. A puncture wound on the left thumb was leaking slightly, but there was no evidence of blood loss, edema or bruising. Approximately 100 min after exposure, the patient experienced a small amount of proximal swelling. Six h after envenomation, he was admitted to the intensive care unit for monitoring. At 10 h after the bite prothrombin time (PT > 100 sec) and international ratio (INR = 9.2) were elevated. The patient was unable to coagulate. He received fresh frozen plasma, cryoprecipitate, and Near Middle East Antivenom. Improvement in clinical status and laboratory parameters were observed after each of 3 doses of antivenom (d-dimer > 1000 and fibrinogen = 137 mg/dL). The patient was monitored overnight, did not require additional antivenom and was discharged as laboratory parameters, vital signs and spread of the necrotic lesion stabilized. Near Middle East Antivenom appears effective in treatment of the hematologic sequelae secondary to African bush viper envenomation.

Adult↗

Direct imaging and determination of the uncompensated spin density in exchange-biased CoO/(CoPt) multilayers.

Magnetic force microscopy (MFM) measurements were performed on an exchange-biased CoO/(CoPt) multilayer sample at 7.5 K. Applying an external magnetic field of up to 7 T saturates the ferromagnetic layer and the remaining uncompensated antiferromagnetic spins at the antiferromagnet-ferromagnet interfaces are imaged with high lateral resolution. The coupling between the uncompensated spins and the spins in the ferromagnet are found to be antiferromagnetic. Quantitative analysis of the MFM images revealed that 7% of the spins at the interface are uncompensated and contribute to the exchange biasing.

Journal Article↗

Change in patients' body weight after 12 months of treatment with glimepiride or glibenclamide in Type 2 diabetes: a multicentre retrospective cohort study.

AIMS/HYPOTHESIS: Our study compared the effects of glimepiride or glibenclamide treatment on body weight over 12 months of treatment in patients with Type 2 diabetes in routine outpatient practice. METHODS: This new retrospective study design used data from physicians in a restricted manner (retrolective). Data from case report forms from 520 patients from 91 randomly selected centres were assessed and covariance analysis performed. RESULTS: The influence of practice and patient characteristics on treatment assignment was low, reflecting the design of randomised controlled trials. Mean weight loss and reduction in body mass index from baseline to study endpoint were greater with glimepiride than with glibenclamide (-2.04+/-3.99 kg vs -0.58+/-3.65 kg, p<0.001; -0.71+/-1.38 kg/m(2) vs -0.20+/-1.28 kg/m(2), p<0.001). Duration of treatment at baseline influenced treatment outcome, but propensity score, sex, age and fasting blood glucose at baseline did not. Both glimepiride and glibenclamide led to decreases in fasting blood glucose (-2.43+/-0.24 mmol/l vs -3.03+/-0.24 mmol/l; p<0.001 vs baseline) and HbA(1c) (-1.23+/-0.09% vs -1.26+/-0.09%; p<0.001 vs baseline). Both treatments were associated with a decrease in serum total cholesterol and low density lipoprotein cholesterol. Triglycerides were lower in the glibenclamide group and high density lipoprotein cholesterol was higher in the glimepiride group only. CONCLUSIONS/INTERPRETATION: Initial treatment of Type 2 diabetes with glimepiride was associated with a significantly greater decrease in body weight and body mass index than treatment with glibenclamide, while providing equivalent glycaemic control.

Blood Glucose↗

Crystallization kinetics of polydisperse colloidal hard spheres: experimental evidence for local fractionation.

We present the crystallization kinetics for two polydisperse hard-sphere particle stocks with differing particle size distributions. One of the latexes had a relatively symmetrical distribution, the other had a more polydisperse distribution, which was highly skewed to smaller sizes. The emerging Bragg reflections from the crystallizing samples were measured using a technique that provides improved statistical averaging over our previous methods. It was observed that, for the more polydisperse particles, the onset of nucleation was delayed by up to an order of magnitude in reduced time, and displayed qualitatively different growth behavior compared to the particles with the more symmetric size distribution. Based on these measurements and time lapse photographs, we propose a growth mechanism whereby crystallization occurs in conjunction with a local fractionation process near the crystal-fluid interface, which significantly alters the kinetics of crystallite nucleation and growth. This fractionation effect becomes more significant as polydispersity or skewness increases.

Journal Article↗

[Pilot study of controlled retrospective analysis (retrolective study design) of care for type 2 diabetics since 1990].

BACKGROUND AND OBJECTIVE: There are few data on the quality of care received by patients with type 2 diabetes under routine conditions and only a few long-term studies that investigated the influence of treatment strategies on the development of clinical endpoints. It was the aim of this study, using retrospectively obtained data, to determine whether it is possible to document over a 10 year period the treatment design and clinical end-points in type 2 diabetics under the care of general practitioners. PATIENTS AND METHODS: General practitioners were randomly selected and informed by independent collaborating monitors about the aim of the study and data documentation. At a second visit by a monitor the completed data forms were audited and entered into a database. Course of treatment was documented by 21 general practitioners, two of them diabetes specialists, for all patients in whom, between 1.1.1990 and 31.12.1993, type 2 diabetes had been diagnosed for the first time (n=455; 251 females, 204 males, mean age 61,5 years). Continuous complete documentation of the course of treatment in the given practice was obtained in 85% of patients over a mean observation period of 8,7 years. 45 myocardial infarcts in 40 patients (9%), 42 strokes in 37 patients (8%), blindness in seven eyes of five patients (1,5%) and 19 amputations (4,2%) were recorded; 72 patients died (15,8%). CONCLUSION: The data of this pilot study indicate that detailed analysis of treatment quality can be obtained in a sizeable cohort, using of a well controlled retrospective (retrolective) study design.

Adult↗

Short versus standard duration oral antibiotic therapy for acute urinary tract infection in children.

BACKGROUND: The optimal duration of oral antibiotic therapy for urinary tract infection (UTI) in children has not been determined. A number of studies have compared single dose therapy to standard therapy for UTI, with mixed results. A course of antibiotics longer than a single dose but shorter than the usual 7-10 days might decrease the relapse rate and still provide some of the benefits of a shortened course of antibiotics. OBJECTIVES: The objective of this review was to assess the benefits and harms of short-course (2-4 days) compared to standard duration (7-14 days) oral antibiotic treatment for acute UTI in children. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register (Cochrane Library Issue 3, 2002) MEDLINE (1966 - September 2002) and EMBASE (1988 -September 2002) without language restriction. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials comparing short-term (2-4 days) with standard (7-14 days) oral antibiotic therapy were selected if they studied children aged three months to 18 years with culture proven UTI. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) with 95% confidence intervals (95% CI). MAIN RESULTS: Ten trials were identified in which 652 children with lower tract UTI were evaluated. There was no significant difference in the frequency of positive urine cultures between the short (2-4 days) and standard duration oral antibiotic therapy (7-14 days) for UTI in children at 0-10 days after treatment (eight studies: RR 1.06; 95% CI 0.64 to 1.76) and at one to 15 months after treatment (10 studies: RR 0.95; 95% CI 0.70 to 1.29). There was no significant difference between short and standard duration therapy in the development of resistant organisms in UTI at the end of treatment (one study: RR 0.57, 95% CI 0.32 to 1.01) or in recurrent UTI (three studies: RR 0.39, 95% CI 0.12 to 1.29). REVIEWER'S CONCLUSIONS: A 2-4 day course of oral antibiotics appears to be as effective as 7-14 days in eradicating lower tract UTI in children.

Acute Disease↗