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Biomedical subjects

C Winter

Publications and source records attributed to C Winter.

At least 19 recordsLinked to original sources
PubMed2006

Real-time imaging of transscleral diode laser cyclophotocoagulation by optical coherence tomography.

PURPOSE: To present optical coherence tomography (OCT) for real-time imaging of cyclophotocoagulation effects. METHODS: In a pilot study, real-time transscleral OCT images were generated during diode laser cyclophotocoagulation in four eyes of four patients suffering from uncontrolled glaucoma using a specially designed contact applicator containing the OCT fiber, a focussing fiber optic and the fiber of the diode laser. RESULTS: When the contact system was used, two layers could be differentiated: a superficial thick hyperreflective complex representing conjunctiva, Tenon's capsule, episclera and sclera, and a thinner hyporeflective layer representing the ciliary body. During cyclophotocoagulation, real-time OCT showed a clear and sudden thickening of the ciliary body in the treated area. CONCLUSION: This new OCT device represents a first step towards visual, real-time imaging of cyclophotocoagulation. After further adaptation of the delivery system, further trials are needed to correlate OCT findings with aqueous production and intraocular pressure.

Ciliary Body↗
PubMed2006

The connecting tubule is the main site of the furosemide-induced urinary acidification by the vacuolar H+-ATPase.

Final urinary acidification is achieved by electrogenic vacuolar H(+)-ATPases expressed in acid-secretory intercalated cells (ICs) in the connecting tubule (CNT) and the cortical (CCD) and initial medullary collecting duct (MCD), respectively. Electrogenic Na(+) reabsorption via epithelial Na(+) channels (ENaCs) in the apical membrane of the segment-specific CNT and collecting duct cells may promote H(+)-ATPases-mediated proton secretion by creating a more lumen-negative voltage. The exact localization where this supposed functional interaction takes place is unknown. We used several mouse models performing renal clearance experiments and assessed the furosemide-induced urinary acidification. Increasing Na(+) delivery to the CNT and CCD by blocking Na(+) reabsorption in the thick ascending limb with furosemide enhanced urinary acidification and net acid excretion. This effect of furosemide was abolished with amiloride or benzamil blocking ENaC action. In mice deficient for the IC-specific B1 subunit of the vacuolar H(+)-ATPase, furosemide led to only a small urinary acidification. In contrast, in mice with a kidney-specific inactivation of the alpha subunit of ENaC in the CCD and MCD, but not in the CNT, furosemide alone and in combination with hydrochlorothiazide induced normal urinary acidification. These results suggest that the B1 vacuolar H(+)-ATPase subunit is necessary for the furosemide-induced acute urinary acidification. Loss of ENaC channels in the CCD and MCD does not affect this acidification. Thus, functional expression of ENaC channels in the CNT is sufficient for furosemide-stimulated urinary acidification and identifies the CNT as a major segment in electrogenic urinary acidification.

Acid-Base Equilibrium↗
PubMed2005

A randomised controlled trial of a new handheld vacuum extraction device.

OBJECTIVE: To evaluate the effectiveness of a new handheld vacuum delivery device. DESIGN: Randomised controlled trial. SETTING: Southmead Hospital, Bristol, UK. POPULATION: One hundred and ninety-four women requiring delivery with vacuum extraction. METHODS: Women were recruited into the study while still in early labour. If during delivery, vacuum extraction was indicated they were then randomly allocated to either a new handheld vacuum device, the Kiwi Omnicup, or to a 'standard' vacuum cup selected by the obstetrician. The 'standard group' consisted of the silastic (66/98, 67%) or the metal cups (32/98, 33%). Study data were recorded at completion of the delivery and at 24-48 hours. An additional brief symptom questionnaire was completed by the mother at 10 days postnatally. Statistical analyses were done on an 'intention-to-treat' basis. MAIN OUTCOME MEASURES: The primary outcome was the successful completion of delivery with the allocated instrument. Secondary outcomes were substantial fetal scalp trauma and substantial maternal trauma. RESULTS: The Omnicup was associated with a significantly higher failure rate than the standard cup [34%vs 21%, odds ratio (OR) = 1.9 (1.01-3.6)]. This difference persisted after adjusting for confounding factors [adjusted OR = 2.25 (1.01-5.0)] and resulted in significantly more forceps deliveries in the Kiwi Omnicup group [22%vs 10%, unadjusted OR = 2.5 (1.1-5.5)]. The caesarean section rates were similar in both groups [9.4%vs 8.2%, OR = 1.2 (0.4-3.2)]. Rates of substantial scalp trauma and maternal trauma were similar in both groups. However, there were more cases of jaundice in the standard cup group [2.3%vs 12.0%, unadjusted OR = 0.18 (0.04-0.82) and adjusted OR = 0.10 (0.01-0.88)]. CONCLUSIONS: The Omnicup is not as successful at achieving a vaginal delivery as the combination of the currently used vacuum cups.

Female↗
PubMed2004

Identification of biotic and abiotic particles by using a combination of optical tweezers and in situ Raman spectroscopy.

A highly versatile setup, which introduces an optical gradient trap into a Raman spectrometer, is presented. The particular configuration, which consists of two lasers, makes trapping independent from the Raman excitation laser and allows a separate adjustment of the trapping and excitation wavelengths. Thus, the excitation wavelength can be chosen according to the needs of the application. We describe the successful application of an optical gradient trap on transparent as well as on reflective, metal-coated microparticles. Raman spectra were recorded from optically trapped polystyrene beads and from single biological cells (e.g., erythrocytes, yeast cells). Also, metal-coated microparticles were trapped and used as surface enhanced Raman spectroscopy (SERS) substrates for tests on yeast cells. Furthermore, the optical gradient trap was combined with a SERS fiber probe. Raman spectra were recorded from trapped red blood cells using the SERS fiber probe for excitation.

Erythrocytes↗
PubMed2004

Changes in function and morphology of normal human skin: evaluation using optical coherence tomography.

BACKGROUND: Optical coherence tomography (OCT) is a noninvasive morphological method for investigating human skin. It allows high-resolution in vivo imaging of inflammatory skin diseases and tumours. Because it is a newly developed method, systematic studies on standardization and on evaluation of factors influencing the representation of the skin have not yet been performed. OBJECTIVES: In this study, normal human skin was treated with various external stimuli which induce changes of function and morphology. Changes in stratum corneum thickness as well as changes induced by pigmentation, oedema and erythema were investigated using OCT. METHODS: Healthy skin of human volunteers was treated with tape stripping, ultraviolet A irradiation, water, histamine, nicotinic acid and various ointments. RESULTS: In the tape stripping experiment, the thickness of the horny layer was quantified and monitored. Pigmentation increased the light attenuation of the tissue, whereas hydration and erythema led to a slight decrease of scattering. Topical treatment of the skin gave a nonspecific increase of penetration depth of the light due to the lower reflectivity of the surface. CONCLUSIONS: There are various physiological conditions which influence optical properties of the skin. These parameters should be considered when performing standardized OCT studies.

Adult↗
PubMed2003

Prevalence of respiratory symptoms in sheep breeders.

BACKGROUND: The European Farmers' Study has indicated that sheep farmers might be at risk for the development of respiratory symptoms. AIMS: To assess the prevalence of respiratory symptoms in sheep breeders and potential work related risk factors. METHODS: All sheep breeders listed in two regions of South Germany were asked to answer a mailed questionnaire on respiratory symptoms, work related respiratory symptoms (WRS), and details of farming. Overall, 325 sheep breeders keeping at least 10 sheep could be included in the survey (response rate 81.9%). The prevalences were compared to the results of the European Farmers' Study. RESULTS: Sheep breeders showed a significantly higher prevalence of asthma related symptoms (prevalence odds ratio (POR) 2.1, 95% CI 1.5 to 3.0), chronic phlegm (POR 4.0, 95% CI 2.8 to 5.9), and WRS (POR 1.7, 95% CI 1.3 to 2.2) after adjusting for age, gender, smoking habits, full time farming, and study centre. In the multiple logistic regression model the risk for asthma related symptoms was doubled in full time farmers (POR 2.3, 95% CI 1.2 to 4.3). The major predictor of WRS was full time farming (POR 1.6, 95% CI 0.93 to 2.7) and the use of chemical footbaths (POR 2.1, 95% CI 1.2 to 3.7). CONCLUSIONS: Sheep breeders might be at high risk for the development of respiratory symptoms. These symptoms may be associated with work intensity and chemical exposure during work. Studies including objective measurements should be performed.

Adolescent↗
PubMed2002

The neuron-specific Ca2+-binding protein caldendrin: gene structure, splice isoforms, and expression in the rat central nervous system.

Caldendrin is the founder member of a recently discovered family of calmodulin-like proteins, which are highly abundant in brain. In this study we examined the organization of the murine and human caldendrin gene as well as the expression pattern of transcripts for caldendrin and two novel splice variants. In addition the distribution of caldendrin in rat brain has been assessed by immunohistochemistry. Caldendrin is localized to the somatodendritic compartment of a subpopulation of mainly principal neurons in brain regions with a laminar organization and is present only at a subset of mature excitatory synapses. Caldendrin immunoreactivity (IR) is tightly associated with the cortical cytoskeleton, enriched in the postsynaptic density (PSD) fraction, and associates late during development with the synaptic cytomatrix. The expression is highly heterogenous within cortex, with highest levels of caldendrin IR in layer III of the piriform and layer II/III of the somatosensory cortex. The segregated cortical distribution to areas, which represent the most important primary sensory systems of the rodent brain, may reflect different requirements for dendritic Ca2+-signaling in these neurons. The presence of caldendrin in the PSD of distinct synapses may have important implications for Ca2+-modulated processes of synaptic plasticity.

Alternative Splicing↗
PubMed2002

[Combination of endovascular procedures with open vascular surgery].

The combination of open surgery with endoluminal catheter techniques offers new chances in the treatment of multi-staged arterial occlusive disease. We report our experiences in 205 patients. In n = 125 patients TEA or bypass were undertaken in the groin with simultaneous catheter intervention proximally or distally. In 31 patients the operation was carried out above knee and in 49 cases below knee. 94 patients with an open operation in the groin and simultaneous iliac catheter interventions are in the follow up. For these interventions the combined secondary patency rate was 77 % after three years.

Adult↗
PubMed2002

Potential dangers of the Valsalva maneuver and adenosine in paroxysmal supraventricular tachycardia--beware preexcitation.

Paroxysmal supraventricular tachycardia (PSVT) is a common clinical problem. Valsalva maneuver and adenosine are effective therapies for many patients with PSVT, although any conversion to an irregular or wide complex tachycardia should prompt consideration of a preexcitation syndrome. We report a case where the Valsalva maneuver and adenosine, in a patient with PSVT and previously undiagnosed Wolff-Parkinson-White syndrome, caused atrial fibrillation and led to a haemodynamically unstable wide complex tachycardia and ventricular fibrillation. In PSVT, where preexcitation has not been excluded, the Valsalva maneuver and adenosine can be potentially dangerous.

Journal Article↗
PubMed2001

Perceptual phenomena after unilateral arm amputation: a pre-post-surgical comparison.

Painful and non-painful phantom phenomena occur frequently after amputations but are rarely investigated in the perioperative stage. The goal of the present study was the assessment of phantom phenomena, pain and changes in primary somatosensory cortex prior to and after upper limb amputation. Two patients who suffered from metastatic carcinoma were examined 2 days prior to and 7 days after the amputation of an arm using comprehensive psychometric assessments and neuroelectric source imaging. Both patients reported phantom limb pain that was similar to their pre-amputation pain. In one patient, reorganization of the mouth area into the deafferented hand area took place immediately after the amputation. In the other patient reorganization had occurred prior to the amputation possibly related to non-use of the arm several years prior to the amputation.

Aged↗
PubMed2001

Terminal-restriction fragment length polymorphism (T-RFLP) screening of a marine archaeal clone library to determine the different phylotypes.

T-RFLP clone characterization (screening) was optimized for a fast and basepair-accurate characterization of clones from marine Archaea collected from the Eastern Mediterranean Sea. Because of the high sensitivity of T-RFLP fingerprinting, a protocol was developed where 10 initial PCR cycles gave detectable terminal fragments from clones. Additionally, forward and reverse primers for PCR were individually labeled and detected simultaneously to assess the suitability of the forward and reverse fragments for T-RFLP screening. Based on independent restriction digests with the tetrameric restriction enzymes HhaI, RsaI and HaeIII to characterize the 49 archaeal clones in our library, the clones were grouped into 13 T-RFLP operational taxonomic units (OTUs). Reverse fragments generally gave less heterogeneous fragments in size. The accuracy of T-RFLP screening was evaluated by sequencing representative clones. Closely related clones ( approximately 97% similarity) could only be resolved with multiple restriction digests where forward and reverse fragments were included in the analysis. All fragments from the clone library were detected in the T-RFLP fingerprint from the complex archaeal community. We found representatives of marine group I, II and III Archaea. Thus, the recently discovered low abundant marine group III Archaea could be clearly differentiated from the other clones in our library and comprised a considerable fraction of the clone library ( approximately 12%). Therefore, our T-RFLP screening approach proved successful in characterizing novel archaeal sequences from the marine environment.

Archaea↗
PubMed2001

Effects of dexamethasone on proliferation, chemotaxis, collagen I, and fibronectin-metabolism of human fetal lung fibroblasts.

Premature infants at risk for bronchopulmonary dysplasia (BPD) are often treated with dexamethasone (Dex), which has been shown to suppress inflammatory processes in the lung. To elucidate a possible direct influence on the fibroproliferative component of the disease, we studied the effects of Dex in therapeutic and supratherapeutic dosages (5-50 nmol/L) on proliferation, chemotaxis, procollagen I, and fibronectin metabolism of human fetal lung fibroblasts in vitro. Proliferation was inhibited by Dex in a dose-dependent manner. Chemotactic activity in response to conditioned medium of human fetal fibroblasts also showed a dose-dependent inhibition after pretreatment with Dex. The amount of procollagen I C-terminal propeptide and fibronectin per cell in the cell culture supernatant was increased in the presence of Dex. Our results show that Dex does not uniformly suppress the fibroproliferative activity of human fetal lung fibroblasts, which may explain in part the unsatisfactory long-term effects of Dex treatment in BPD.

Anti-Inflammatory Agents↗
PubMed2001

[The phantom and stump phenomena interview (PSPI)].

RESEARCH QUESTION: A structured German-language interview was developed for the assessment of painful and non-painful phantom and stump phenomena after amputation. The aim was a thorough assessment of the quality, quantity and time course of these phenomena, which is of scientific as well as therapeutic relevance. METHODS: Each phenomenon was assessed using visual analogue scales as well as qualitative descriptors adapted from the McGill Pain Inventory and from literature reports. The factor structure and psychometric properties of the interview were evaluated in a sample of 139 upper and lower limb amputees. Test-retest coefficients were obtained in a subset of 20 amputees. RESULTS: As expected, all pain-related scales showed a two-dimensional internal structure with the factors "affective pain" and "sensory pain". For the non-painful phantom sensations, three factors "general/kinesthetic phantom sensations", "phantom movements" and "paresthesias" were obtained, while for non-painful stump sensations only one general factor emerged. The internal consistency was high with respect to the pain-related scales and was still satisfying for the scales that cover nonpainful phantom and stump phenomena. All scales have sufficient validity. Test-retest coefficients suggest a satisfactory stability of all scales that assess present phenomena, while the stability of the retrospective scales is markedly lower and in some cases insufficient. CONCLUSIONS: The phantom and stump phenomena interview is a highly reliable and valid instrument to assess present perceptual phenomena after amputation. Only the included retrospective scales apparently show low stability scores over time. This raises the more general question of the validity of retrospective pain reports.

Adult↗
PubMed2001

The relationship of perceptual phenomena and cortical reorganization in upper extremity amputees.

In this study 16 unilateral upper extremity amputees participated in a comprehensive psychophysiological examination that included the assessment of painful and non-painful phantom and stump sensations, thermal and electric perception as well as two-point discrimination thresholds, the detailed analysis of referred sensation and the measurement of reorganizational changes in primary somatosensory cortex using neuroelectric source imaging. Reorganization of the primary somatosensory cortex was associated with increased habitual phantom limb pain, telescoping, non-painful stump sensations and painful referred sensation induced by painful stimulation. It was unrelated to non-painful phantom sensations, non-painful referred sensation elicited by painful or non-painful stimulation, painful referred sensation elicited by non-painful stimulation, perception thresholds and stump pain. These data substantiate the hypothesis that painful and non-painful phantom phenomena are mediated by different neural substrates.

Adaptation, Physiological↗
PubMed2001

The circadian clock of fruit flies is blind after elimination of all known photoreceptors.

Circadian rhythms are entrained by light to follow the daily solar cycle. We show that Drosophila uses at least three light input pathways for this entrainment: (1) cryptochrome, acting in the pacemaker cells themselves, (2) the compound eyes, and (3) extraocular photoreception, possibly involving an internal structure known as the Hofbauer-Buchner eyelet, which is located underneath the compound eye and projects to the pacemaker center in the brain. Although influencing the circadian system in different ways, each input pathway appears capable of entraining circadian rhythms at the molecular and behavioral level. This entrainment is completely abolished in glass(60j) cry(b) double mutants, which lack all known external and internal eye structures in addition to being devoid of cryptochrome.

Animals↗
PubMed2001

Fatal form of phaeochromocytoma presenting as acute pyelonephritis.

We report the case of a young man who presented with a clinical picture of acute pyelonephritis. Within 3 h of admission, the patient developed acute respiratory distress associated with tachycardia and shock, and he was transferred to the intensive care unit. Mechanical ventilation of the lungs and symptomatic treatment were started immediately. Abdominal ultrasound revealed the presence of an adrenal tumour with central necrosis indicating a probable phaeochromocytoma. There was no sign of pyelonephritis. Ventricular fibrillation followed by asystole occurred soon after admission. The suddenness of the patient's death did not allow time for further investigation and therapy. The severity of the clinical signs was probably related to a massive release of catecholamines because of necrosis of the tumour, which may have been worsened by the diagnostic procedures performed to investigate the clinical symptoms and signs of acute pyelonephritis.

Acute Disease↗
PubMed2001

Impact of UV radiation on bacterioplankton community composition.

The potential effect of UV radiation on the composition of coastal marine bacterioplankton communities was investigated. Dilution cultures with seawater collected from the surface mixed layer of the coastal North Sea were exposed to different ranges of natural or artificial solar radiation for up to two diurnal cycles. The composition of the bacterioplankton community prior to exposure was compared to that after exposure to the different radiation regimes using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA and 16S ribosomal DNA. Only minor changes in the composition of the bacterial community in the different radiation regimes were detectable. Sequencing of selected bands obtained by DGGE revealed that some species of the Flexibacter-Cytophaga-Bacteroides (FCB) group were sensitive to UV radiation while other species of the FCB group were resistant. Overall, only up to approximately 10% of the operational taxonomic units present in the dilution cultures appeared to be affected by UV radiation. Thus, we conclude that UV radiation has little effect on the composition of coastal marine bacterioplankton communities in the North Sea.

Animals↗