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Biomedical subjects

R Winter

Publications and source records attributed to R Winter.

At least 37 records · Page 2Linked to original sources
PubMed1996

Comparison of bronchoalveolar lavage and catheter lavage to confirm ventilator-associated lower respiratory tract infection.

Lower respiratory tract infection (LRTI) is a well recognised complication of artificial ventilation in intensive care units (ICU). Ideally, specimens for microbiological analysis should be obtained during bronchoscopy, but this is not always possible. Therefore, the microbiological diagnosis of lower respiratory tract infection by broncho-alveolar lavage (BAL) obtained during bronchoscopy was compared with catheter lavage (CL) with a balloon-tipped catheter. Adult patients with clinical evidence of lower respiratory tract infection in an adult ICU were randomly assigned to undergo BAL followed by CL or vice versa. Forty ml of normal saline 0.9% were instilled and then aspirated with a flexible bronchoscope to obtain BAL. A similar volume was instilled and aspirated with a 12-gauge Foley balloon-tipped catheter to obtain a CL sample. The number of inflammatory cells, epithelial cells and organisms seen by microscopy were quantified. Culture results were semi-quantified and classified as negative, positive, equivocal or contaminated. Seventy-nine paired specimens were obtained from 66 patients, including specimens from 10 patients taken on two or more occasions. Only 20% of BAL and 16% of CL had one or more epithelial cells and bacteria were seen in 26 BAL and 21 CL specimens, respectively; 35% of BAL and CL specimens were positive and there was a discrepancy in the culture result in only two cases. Staphylococcus aureus was the pathogen isolated most frequently and polymicrobial lower respiratory infection was diagnosed on 10 occasions (15%). CL fluid is as reliable as BAL in diagnosing lower respiratory tract infection in ICU. This approach does not require bronchoscopic expertise and utilises convenient laboratory techniques.

Adolescent↗
PubMed1996

Conformational differences of ovine and human corticotropin releasing hormone. A CD, IR, NMR and dynamic light scattering study.

The differences in the conformational properties of ovine (o) and human (h) CRH in aqueous solution, structure-inducing TFE and in the presence of detergent micelles and lipid vesicles have been investigated by circular dichroism, Fourier transform infrared spectroscopy, NMR and dynamic light scattering. o-CRH was found to exist as a monomer with little regular structure in dilute aqueous solution. Association at concentrations higher than 10-3 mol/L results predominantly in dimers. The induction of a substantial amount of intermolecular beta-structure seems to be the result of interactions of the C-terminal hexapeptide and the N-terminal region 6-12 of o-CRH chains in antiparallel orientation. In contrast, h-CRH exhibits a high tendency of association which is highly sensitive to the pH. The formation of tetramers at millimolar peptide concentration is related to a helical content of ca. 50%. The potentially helical, highly hydrophobic region 6-20 enlarged by more hydrophobic residues in position 23 and 25 is proposed to stabilize the h-CRH associates. In the presence of structure inducing TFE (> 40% v) both CRH peptides exist as monomers. o-CRH reveals about 72% helicity, in h-CRH the formation of about 85% helix is observed. The differences in helicity of the two CRH molecules are located in the C-terminal heptapeptide, as concluded on the basis of NMR studies. Both peptides bind to detergent micelles at pH 4 as well as 7.4 associated with an increase in the alpha-helical content. Interaction of the two peptides with DMPC vesicles was found exclusively at pH 4. Above the phase transition temperature of DMPC the alpha-helical content in h-CRH increases slightly; however, o-CRH reveals a substantial amount of beta-type structure. The intramolecular type of beta-structure is associated with a deeper insertion of the o-CRH region 6-12 into the hydrophobic region of the lipid bilayer, whereas the corresponding region of h-CRH is kept in the bilayer surface. The higher helicity of h-CRH might explain to some extent its higher affinity to the CRH receptor, CRH antibodies and the CRH binding protein.

Animals↗
PubMed1996

Defined large-scale alterations of the human cytomegalovirus genome constructed by cotransfection of overlapping cosmids.

We have constructed defined human cytomegalovirus (CMV) mutants by cotransfecting overlapping cosmid clones spanning the 230-kbp genome. Using this strategy, we have introduced a 13-kbp region of DNA from a virulent strain of CMV into a defined position within the avirulent CMV(Towne) genome. Although more than 80% of the genome of these recombinant viruses was derived from Towne DNA, their plaque morphology more closely resembled that of Toledo. To date, CMV is the largest virus and requires the greatest number of cosmids to be regenerated via overlapping cosmid cotransfection.

Cell Line↗
PubMed1996

[Helminth burden of slaughter sheep in Upper Bavaria. 1: Species spectrum, infestation extent and infestation intensity].

The helminth fauna of 136 slaughtered sheep (99 lambs < 1 year, and 37 sheep > or = 1 year) from Upper Bavaria, Germany, was examined. In all 2 species of trematodes, 3 species of cestodes and 24 species of nematodes were found. All the animals harboured gastrointestinal nematodes, 9 of them liver flukes, 33 Moniezia spp., 19 Cysticercus tenuicollis, and one sheep Setaria sp. Lungworms were not seen. The most prevalent species were Cooperia curticei (74.3%), Trichuris ovis (69.1%), Ostertagia circumcincta (68.4%), Oesophagostomum venulosum (63.2%) and Chabertia ovina (61.8%). The highest mean wormburden was seen in Cooperia curticei (12471) followed by Trichostrongylus axei (1856), Trichostrongylus colubriformis (1752), Nematodirus filicollis (1551) and Nematodirus battus (1238). In both lambs and older sheep the small intestine harboured the highest wormburden followed by abomasum and large intestine. The total nematode counts were much higher in lambs than in older sheep. The lambs harboured more intestinal nematodes than older sheep but fewer abomasal worms.

Abattoirs↗
PubMed1996

Vascular MR contrast enhancement in cerebrovascular disease.

PURPOSE: To determine the significance of vascular enhancement in stroke patients with and without permanent neurologic deficit. METHODS: We prospectively studied two groups of patients with spin-echo MR imaging before and after injection of gadopentetate dimeglumine. In the patients in group 1 (12 women, 22 men; age range, 32 to 76 years), who had permanent neurologic deficit caused by recent ischemic brain infarction, we obtained 3 to 13 serial MR images during follow-up examination. Group 2 consisted of 26 patients (14 women, 12 men; age range, 54 to 81 years) with transient neurologic deficit caused by angiographically proved high-grade stenosis or occlusion of the internal carotid artery. RESULTS: Vascular enhancement was present in 59% of patients in group 1 and in 65% of patients of group 2. In group 1, the frequency of vascular enhancement declined steadily over several weeks, but it was still present in single cases even after 3 months. Vascular enhancement correlated positively with the extent of brain infarction in group 1 and with the degree of carotid stenosis in group 2. CONCLUSION: Vascular enhancement as shown by MR imaging may herald ischemic brain infarction and could persist over several weeks in areas that show collateral flow after infarction has occurred.

Adult↗
PubMed1996

[HLA typing of donor corneas with extended post mortem time].

In case of high-risk patients cornea transplantation should be carried out using HLA-matched donor corneas to minimize the risk of rejection. HLA typing using blood lymphocytes of the donor is impossible because of the long post-mortem times. Alternatively, HLA typing can be performed using retinal pigment epithelium (RPE). Nevertheless, this method is limited by increasing post-mortem times. The aim of the present study was the optimization of culture conditions for RPE cells isolated from donor eyes with long post-mortem times. The HLA type should be evaluated during an acceptable period of organ preservation of the corresponding cornea. In different steps the method for isolation of the cells was optimized and a growth medium for RPE cells was established. Various supplements, including uvea-conditioned medium, were assessed using growth assays. The optimization of culture conditions led to an increase in the estimation of the complete HLA I and HLA II antigens from 36% to 74%. The time needed for the typing-procedure could be reduced from 38 to 17 days (average). At present 30% of the donor tissue with long post-mortem times can be typed in less than 14 days.

Cell Division↗
PubMed1996

[Glaucoma and aircraft pilot fitness].

Two completely different questions arise when considering glaucoma and fitness to fly: Firstly, what is the risk for a passenger with glaucoma? Secondly, what is the flight safety risk connected with pilots suffering from glaucoma? National requirements and international standards pay little regard to this disease. This is astonishing, given that the perception of flight information in the peripheral visual field is of great importance in the cockpit. On one hand, diagnostic glaucoma examinations for pilots are mainly insufficient, and on the other, progressive visual field deficiencies may go undetected because of long intervals between examinations. Intraocular pressure may increase while flying in aircraft, e.g. in the case of negative g-load. Frequent flights at high altitudes without pressurized cabin air and with decreased oxygen supply, and therefore decreased tissue oxygen saturation, may represent a risk, especially for patients with progressive nerve fibre loss.

Aircraft↗
PubMed1996

[Recognition of cardiac normal variants as the cause of cerebral ischemia: significance of transesophageal echocardiography].

The significance of cardiac normal variants such as patent foramen ovale (PFO), mitral valve prolapse (MVP) and atrial septal aneurysm (ASA) as potential intracardiac sources of embolism in patients with cerebral ischemia is still discussed controversially. In the present study, we determined the prevalence of PFO, MVP and ASA in patients with suspected embolic cerebral events after exclusion of cerebrovascular disease. Therefore, 164 consecutive patients with suspected embolic cerebral events as suggested by cranial computer tomography or clinical neurological examination were divided into two groups: patients with "classical" potential cardiac source of embolism (group I, n = 81, age 52 +/- 10 years) and patients without such potential cardiac sources of embolism (group II, n = 83, age 56 +/- 12 years). The prevalence of PFO, but not that of MVP and ASA, was significantly higher in group I than in group II (group I: 33.3% vs. group II: 2.4%; chi-square 88.5, p < 0.0001). In the absence of "classical" potential cardiac sources of embolism transesophageal echocardiography reveals a PFO in approximately 30% of the cases. This finding supports the significance of PFO as a potential cardiac source of embolism.

Adult↗
PubMed1995

Previously apparently undescribed syndrome: shallow orbits, ptosis, coloboma, trigonocephaly, gyral malformations, and mental and growth retardation.

We describe 2 children with severe ptosis, trigonocephaly, broad nasal bridge, and major brain malformation. A total of 8 children have been reported who share most of these findings. Two of the individuals have had identical pericentric inversions involving chromosome 2p12-q14. These cases appear to represent a unique malformation syndrome.

Abnormalities, Multiple↗
PubMed1995

Correlation of histological tumor vascularization and Doppler sonography in patients with malignant melanoma of the choroid.

BACKGROUND: In previous studies Doppler sonography was proven to the useful for diagnostics and follow-up of malignant melanomas of the choroid. METHODS: To evaluate the correlation between Doppler sonographical findings and the histological tumor vascularization, we examined five eyes of five patients with malignant melanoma of the choroid before enucleation with an ATL Ultramark-8 Duplex scanner and compared these results with computerized planimetry of histological tumor vascularization after immunohistochemical staining of vascular endothelium with anti-factor-VIII antibodies. RESULTS: We found no definite correlation of flow velocities with histological parameters of tumor vascularization. The tendency was for a decrease in maximum flow velocities as histological vascularization increased. CONCLUSIONS: Due to (1) the usual lack of sensitivity parameters of the used Duplex device for the clinical user and (2) the unpredictable branching pattern within a melanoma resulting in an unknown angle of incidence of the Doppler beam, we conclude that the quantitative results of Doppler sonography require cautious interpretation. Nevertheless, presence or absence of Doppler shifts is a valuable parameter for the follow-up of irradiated tumors.

Blood Flow Velocity↗
PubMed1995

Temperature- and pressure-dependent phase behavior of monoacylglycerides monoolein and monoelaidin.

We used x-ray and neutron diffraction to study the temperature- and pressure-dependent structure and phase behavior of the monoacylglycerides 1-monoelaidin (ME) and 1-monoolein (MO) in excess water. The monoacylglycerides were chosen for investigation of their phase behavior because they exhibit mesomorphic phases with one-, two-, and three-dimensional periodicity, such as lamellar, an inverted hexagonal and bicontinuous cubic phases, in a rather easily accessible temperature and pressure range. We studied the structure, stability, and transformations of the different phases over a wide temperature and pressure range, explored the epitaxial relations that exist between different phases, and established a relationship between the chemical structure of the lipid molecules and their phase behavior. For both systems, a temperature-pressure phase diagram has been determined in the temperature range from 0 to 100 degrees C at pressures from ambient up to 1400 bar, and drastic differences in phase behavior are found for the two systems. In MO-water dispersions, the cubic phase Pn3m extends over a large phase field in the T,p-plane. At temperatures above 95 degrees C, the inverted hexagonal phase is found. In the lower temperature region, a crystalline lamellar phase is induced at higher pressures. The phases found in ME-water include the lamellar crystalline Lc phase, the L beta gel phase, the L alpha liquid-crystalline phase, and two cubic phases belonging to the crystallographic space groups Im3m and Pn3m. In addition, the existence of metastable phases has been exploited. Between coexisting metastable cubic structures, a metric relationship has been found that is predicted theoretically on the basis of the curvature elastic energy approximation only.

Biophysical Phenomena↗
PubMed1995

Incidence of bacterial and fungal contamination of donor corneas preserved by organ culture.

We reviewed the results of sterility testing from culture media of 1,134 donor corneas preserved by organ culture at 37 degrees C in our eye bank. All corneas were stored in minimal essential medium containing 2% fetal calf serum, 0.1 mg/ml penicillin G, 0.1 mg/ml streptomycin, and 2.5 micrograms/ml amphotericin B. After removal of ocular adnexal tissue, donor globes were rinsed with sterile saline solution, incubated in 3% polyvinylpyrrolidone-iodine solution for 3-5 min, and subsequently rinsed again with sterile saline solution. Samples for microbiological evaluation were obtained from the initial evaluation medium, at every medium change (every 10 days), and from the medium used for deswelling of the individual cornea 1 day before transplantation. Incidence of contamination was 0.53% (6 of 1,134 corneas). Three corneas were contaminated by Micrococcus species, three by fungi. We conclude from our study that a combination of rinsing donor globes with sterile saline solution, the initial use of a disinfectant, and the employment of penicillin/streptomycin and amphotericin B in the organ culture medium, which have been commonly used in cell culture for decades, result in a low incidence of bacterial and fungal contamination of corneas preserved by organ culture.

Bacteria↗