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Biomedical subjects

A Schaper

Publications and source records attributed to A Schaper.

At least 19 recordsLinked to original sources
PubMed2004

Prognosis factors in incisional hernia surgery: 25 years of experience.

BACKGROUND: Incisional hernia underwent a change from conventional techniques to mesh implantation. The relevance of different factors, like operative technique, mesh material, and patient-related parameters concerning the outcome following mesh repair, are still under debate. METHODS: In a comparative retrospective study of 421 incisional hernia operations on 348 patients, we investigated 241 Mayo procedures and 180 mesh repairs over a 25-year period. In addition to the quality of life following mesh implantation, the prognostic relevance of demographic, preoperative and intraoperative parameters, surgical technique, mesh material, and the surgeon's experience were analysed, both in a univariate and multivariate manner. RESULTS: With a mean follow-up of 9.7+/-8.8 years, the total recurrence rate following Mayo overlap was 37%, in contrast to 15% after mesh implantation (P=0.001). Mesh size was the only significant prognostic factor concerning quality of life following mesh implantation, and 86% of the patients with mesh repair were satisfied. The complication rate was determined significantly by patients' risk factors, size of hernia, operative technique, and the surgeon's experience, whereas the rate of recurrences was significantly influenced by the parameters obesity (BMI>25), size of hernia, and surgical experience. The recurrence rate decreased significantly with surgeon's experience-a minimum of 16 mesh repairs led to a recurrence rate of less than 10%. CONCLUSIONS: Only the mesh repair revealed acceptable recurrence rates with high patient comfort. From a surgical point of view, the most important prognostic factor following mesh repair is the surgeon's experience.

Female↗
PubMed2003

[Cocaine-body-packing. Infrequent indication for laparotomy].

INTRODUCTION: Body-packers or "mules" are drug smugglers who swallow cocaine-filled condoms in order to conceal them during air travel. Body pushers hide drug packages in the rectum or vagina. In a cooperative effort between the Frankfurt Airport Clinic and the GIZ-Nord (Goettingen University poison control center), we performed a retrospective study and developed an algorithm for the problem of "rupture of a cocaine-filled condom in a body-packer." METHODS: In a retrospective analysis, the data of all cocaine body-packers and body pushers who were identified at Frankfurt International Airport from 1985 to 2001 were evaluated.Temporal development, demographic data, and surgical aspects were of special interest. RESULTS: From 1985 to 2001 a total of 280 body pushers and 2880 body-packers were identified: 63 "mules" (2.2%) developed symptoms of severe cocaine intoxication following rupture of a condom. Emergency laparotomy was performed on 20 patients (i.e., 32% of all symptomatic body-packers) and the condoms were removed, while 43 body-packers (68%) died before surgical therapy could be initiated. All operated patients survived. CONCLUSION: Severe cocaine intoxication is life threatening. Patients die from complications caused by generalized vasoconstriction. If the reason for severe cocaine intoxication is the rupture of a cocaine-filled condom,the only possible therapy consists of immediate laparotomy for removal of the condoms.

Adolescent↗
PubMed2001

Chronic heart failure in the community: missed diagnosis and missed opportunities.

BACKGROUND: The aim of this study was to determine the incidence of congestive heart failure (CHF) in patients discharged from a hospital without a diagnosis of CHF who were admitted with shortness of breath and had a low left ventricular ejection fraction (LVEF). CHF is a devastating disease in terms of financial cost, prevalence, and effect on morbidity and mortality. The true incidence rate is not known because of reliance on discharge records and death certificates, and because diagnosis remains a clinical judgment. METHODS AND RESULTS: CHF was diagnosed by the Framingham criteria. We retrospectively reviewed the records of 225 randomly selected patients admitted with a complaint of shortness of breath and discharged without a diagnosis of CHF (group 1). We compared group 1 with patients admitted at the same time with a diagnosis of CHF and of similar age and LVEF (group 2). In group 1, 100 patients had a low LVEF (< or =40%) and 51% met criteria for CHF that had been missed. Readmission rate was high (42%). Mortality at 12 months was 18%. Rate of cardiomegaly on x-ray films was similar in groups 1 and 2 (64.6% v 64.4%, respectively). Third heart sound (39% v 10%; P <.001) and heart rate > 120 beats/min (41.7% v 12.5%; P <.001) were significantly more frequent in group 1. By contrast, signs and symptoms suggestive of fluid overload were more frequent in group 2. CONCLUSIONS: Many patients admitted with shortness of breath and low LVEF have CHF but are not diagnosed. Physicians are more likely to miss CHF in patients presenting without signs of fluid overload even when third heart sound is present with resting tachycardia. A missed diagnosis of CHF is associated with a high readmission rate, multiple admissions, and a mortality rate comparable to that of patients with newly diagnosed CHF.

Aged↗
PubMed2001

Myocardial infarction in young adults with low-density lipoprotein cholesterol levels < or = 100 mg/dL: clinical profile and 1-year outcomes.

STUDY OBJECTIVES: To define the clinical profile of young adults with optimal low-density lipoprotein (LDL) cholesterol levels who present with acute myocardial infarctions (MIs); to compare and contrast differences in the clinical profiles of young adults admitted to the hospital with MIs who have LDL cholesterol levels < or = 100 mg/dL and those with LDL cholesterol values > or = 160 mg/dL; and to evaluate the clinical outcomes for the two groups at 1 year. DESIGN: A retrospective chart review was conducted on all young men (55 years) and women (65 years) admitted to the hospital for MIs within a 2-year period (n = 232). A history of cardiovascular risk factors and 1-year outcomes were obtained. SETTING: Rural community medical center serving a tri-state area in the midwestern United States. PATIENTS: Patients were included in this analysis if (1) a lipid profile was drawn within 24 h of hospital admission and (2) the patient was not receiving a statin medication on hospital admission. MEASUREMENTS AND RESULTS: Of the 183 patients who met the inclusion criteria, as many as 68% (124 patients) had LDL cholesterol levels of < or = 130 mg/dL, 29% (53 patients) had LDL cholesterol level of < or = 100 mg/dL, and only 14% (26 patients) had LDL cholesterol levels of > or = 160 mg/dL. Patients were categorized into group 1 if their LDL cholesterol level was < or = 100 mg/dL and were categorized into group 2 if their LDL cholesterol level was > or = 160 mg/dL. In group 2, 92% of patients were placed on a statin medication. By 1 year, the mean LDL cholesterol level had decreased from 188 to 106 mg/dL. The rate of coronary artery bypass graft and percutaneous coronary intervention procedures was similar between groups. Hospital readmission rates (43.4% vs 50%, respectively) and 1-year mortality rates (9% vs 8%, respectively) were not different between groups group 1 and 2. CONCLUSIONS: Young adults experiencing acute MIs typically have acceptable cholesterol levels (ie, < or = 130 mg/dL) or optimal values (ie, < or = 100 mg/dL). In those patients with abnormal cholesterol levels, a combined strategy of aggressive intervention and adherence to secondary prevention protocols including lipid control is successful in improving outcomes.

Adult↗
PubMed2000

Complementary visualization of mitotic barley chromatin by field-emission scanning electron microscopy and scanning force microscopy.

The surface structure of mitotic barley chromatin was studied by field-emission scanning electron microscopy (FESEM) and scanning force microscopy (SFM). Different stages of the cell cycle were accessible after a cell suspension was dropped onto a glass surface, chemical fixed, and critically point dried. Imaging was carried out with metal-coated specimen or uncoated specimen (only for SFM). The spatial contour of the chromatin could be resolved by SFM correlating to FESEM data. The experimentally determined volume of the residue chromatin during mitosis was within the range of 65-85 microm(3). A comparison with the theoretically calculated volume indicated a contribution of about 40% of internal cavities. Decondensation of chromosomes by proteinase K led to a drastic decrease in the chromosome volume, and a 3-D netlike architecture of the residue nucleoprotein material, similar to that in the intact chromosome, was obvious. Incubation of metaphase chromosomes in citrate buffer permitted access to different levels of chromatin packing. We imaged intact chromosomes in liquid by SFM without any intermediate drying step. A granular surface was obvious but with an appreciably lower resolution. Under similar imaging conditions proteinase K-treated chromosomes exhibited low topographic contrast but were susceptible to plastic deformations.

Chromatin↗
PubMed2000

Mild hypercholesterolemia and premature heart disease: do the national criteria underestimate disease risk?

OBJECTIVES: To determine the frequency of hospital admissions for acute coronary syndrome in young adults and to examine the risk factors that predispose to the development of premature heart disease. BACKGROUND: Significant coronary heart disease (CHD) is considered rare in the young adult. Current guidelines do not recommend treatment of mild cholesterol abnormalities for primary prevention of CHD in the young. METHODS: This is a large case series of 449 adults (< or =50 years) admitted to the hospital with acute coronary syndrome. A history of cardiovascular risk factors and lipid profile were recorded. The presence and extent of CHD were established. RESULTS: Mean patient age was 44 +/- 6 years. Documented CHD was present in 61% of hospital admissions. Multivariate analysis revealed that history of hypercholesterolemia, history of smoking and diabetes were independently associated with premature CHD. The fasting lipid profiles were only borderline to mildly abnormal. Serum total cholesterol, low-density lipoprotein (LDL) and triglyceride levels were not different in cases compared with control subjects. Nearly half (49%) of those with LDL levels of > or =160 mg/dl had only one additional risk factor or none. Despite this, a history of hypercholesterolemia had independent and incremental value on other risk factors for the likelihood of premature CHD. CONCLUSIONS: The magnitude of hospital admissions relating to premature CHD is high. In this population, the presence of borderline or mild hypercholesterolemia has significant effects on the development of premature CHD. These observations have significant implications in the development of guidelines for primary prevention of premature CHD.

Adult↗
PubMed1997

Tumor suppressor protein p53 binds preferentially to supercoiled DNA.

Wild type human tumor suppressor protein p53 (expressed in insect cells) binds strongly to negatively supercoiled (sc) plasmid DNA at a native superhelix density, as evidenced by electrophoretic retardation of scDNA in agarose gels and imaging by scanning force microscopy (SFM). The binding occurs both in the presence and absence of the p53 consensus sequence. At relatively low p53/DNA ratios, binding of p53 to scDNA results in the appearance of several retarded DNA bands on the gels, similar to a conventional topoisomer ladder generated enzymatically. However, after removal of p53 by deproteination, the original mobility of the scDNA is recovered, indicating that the reduction of torsional stress accompanying p53 binding does not reflect changes in linking number. In DNA samples partially relaxed by topoisomerase I p53 binds preferentially to the scDNA molecules with the largest negative superhelix density. SFM imaging of the p53/scDNA complex reveals a partial or total relaxation of the compact scDNA, the degree of which increases with the number of bound p53 molecules. Competition assays with linear DNA reveal a preference of p53 for scDNA. In addition, scDNA induces dissociation of p53 from a preformed complex with a DNA fragment (474 bp) containing the consensus sequence. We conclude that the affinity of p53 for negatively supercoiled DNA is greater than that for the consensus sequence in linear fragments. However, thermally denatured linearized plasmid DNA is efficient in competing for the binding of p53 to scDNA, although the first retarded band (presumed to contain one bound p53 molecule) is retained in the case of the plasmid containing the consensus sequence. Thus, it appears that interactions involving both the core domain and the C-terminal domain regulate the binding of p53 to scDNA. The above results are not restricted to human p53; the wild type rat p53 protein also results in the retardation of scDNA on agarose gels. The biological implications of the novel DNA binding activities of p53 are discussed.

Animals↗
PubMed1996

Sequence-specific labeling of superhelical DNA by triple helix formation and psoralen crosslinking.

Site-specific labeling of covalently closed circular DNA was achieved by using triple helix-forming oligonucleotides 10, 11 and 27 nt in length. The sequences consisted exclusively of pyrimidines (C and T) with a reactive psoralen at the 5'-end and a biotin at the 3'-end. The probes were directed to different target sites on the plasmids pUC18 (2686 bp), pUC18/4A (2799 bp) and pUC1 8/4A-H 1 (2530 bp). After triple helix formation at acid pH the oligonucleotides were photocrosslinked to the target DNAs via the psoralen moiety, endowing the covalent adduct with unconditional stability, e.g. under conditions unfavorable for preservation of the triplex, such as neutral pH. Complex formation was monitored after polyacrylamide gel electrophoresis by streptavidin-alkaline phosphatase (SAP)-induced chemiluminescence. The yield of triple helix increased with the molar ratio of oligonucleotide to target and the length of the probe sequence (27mer > 11mer). The covalent adduct DNA were visualized by scanning force microscopy (SFM) using avidin or streptavidin as protein tags for the biotin group on the oligonucleotide probes. We discuss the versatility of triple helix DNA complexes for studying the conformation of superhelical DNA.

Base Sequence↗
PubMed1996

Striving for atomic resolution in biomolecular topography: the scanning force microscope (SFM).

The invention in 1986 of scanning force microscopy (SFM) provided a new and powerful tool for the investigation of biological structures. SFM yields a three-dimensional view at nanometer resolution of the surface topography associated with biological objects. The potential for imaging either macromolecules or biomolecules and cells under native (physiological) conditions is currently being exploited to obtain functional information at the molecular level. In addition, the forces involved in individual bimolecular interactions are being assessed under static and dynamic conditions. In this report we focus on the imaging capability of the SFM. The rather broad spectrum of applications represented is intended to orient the prospective user of biological SFM.

Animals↗
PubMed1996

Peripheral joint laxity increases in pregnancy but does not correlate with serum relaxin levels.

OBJECTIVE: Our purpose was to evaluate peripheral joint laxity during pregnancy and to determine whether serum relaxin levels are associated with increased joint laxity. STUDY DESIGN: A prospective observational study was performed. RESULTS: A significant increase in joint laxity was found in five of seven peripheral joints over the course of the pregnancy and post partum. There was no correlation with serum relaxin levels. There were no significant differences in joint laxity on the basis of parity, age, or prepregnancy exercise levels. CONCLUSIONS: Peripheral joint laxity is noted to increase as pregnancy progresses. The cause of this change is undetermined.

Adult↗
PubMed1995

Structural hierarchy in the clustering of HLA class I molecules in the plasma membrane of human lymphoblastoid cells.

Major histocompatibility complex (MHC) class I antigens in the plasma membranes of human T (HUT-102B2) and B (JY) lymphoma cells were probed by immunochemical reagents using fluorescence, transmission electron, and scanning force microscopies. Fluorescent labels were attached to monoclonal antibodies W6/32 or KE-2 directed against the heavy chain of HLA class I (A, B, C) and L368 or HB28 against the beta 2-microglobulin light chain. The topological distribution in the nanometer range was studied by photobleaching fluorescence resonance energy transfer (pbFRET) on single cells. A nonrandom codistribution pattern of MHC class I molecules was observed over distances of 2-10 nm. A second, nonrandom, and larger-scale topological organization of the MHC class I antigens was detected by indirect immunogold labeling and imaging by transmission electron microscopy (TEM) and scanning force microscopy (SFM). Although some differences in antigen distribution between the B- and T-cell lines were detected by pbFRET, both cell lines exhibited similar clustering patterns by TEM and SFM. Such defined molecular distributions on the surfaces of cells of the immune system may reflect an underlying specialization of membrane lipid domains and fulfill important functional roles in cell-cell contacts and signal transduction.

Adult↗
PubMed1995

Subclavian hemodialysis catheter infections: a prospective, randomized trial of an attachable silver-impregnated cuff for prevention of catheter-related infections.

OBJECTIVE: To determine if an attachable silver-impregnated cuff is effective in reducing subclavian hemodialysis catheter-related infections. DESIGN: Prospective, randomized, nonblinded study. SETTING: Community teaching hospital. PATIENTS: One hundred one acute and chronic renal failure patients requiring subclavian venipuncture and catheterization. After randomization, 47 patients underwent subclavian catheterization with a silver-impregnated cuff (Ag-CC), and 54 patients had routine catheter (RC) placements. MEASUREMENTS: Multiple presumed predictor variables for catheter-related infections, exit site infection rate, bacteremia rates, and semiquantitative cultures of all catheters.

Analysis of Variance↗
PubMed1995

Scanning force microscopy of microtubules and polymorphic tubulin assemblies in air and in liquid.

We have investigated microtubules (MTs) and polymorphic assemblies, formed in vitro from isolated microtubule protein, by scanning force microscopy (SFM) in air and in liquid. Immobilization of MTs was achieved by placing a drop of the assembly solution on a polylysine-coated coverslip. After washing with taxol and air drying, the characteristic microtubular fibrous morphology appeared in the SFM. The MTs formed a network similar to that obtained by transmission electron microscopy (TEM). A height of approximately 9.5 nm for dried MTs was computed from the surface topography. Glutaraldehyde fixation of the MTs yielded higher structures (approximately 14 nm), which swelled to approximately 20 nm after rehydration, a value close to the MT diameter of approximately 25 nm determined from TEM images of ultrathin sections. The protofilament pattern of the MTs and surface attached MT-associated proteins were not apparent from SFM, although the height along the long axis of the MTs appeared slightly modulated. In addition to MTs, various polymorphic tubulin assemblies including ribbons, hoops and double-walled MTs were visualized by SFM.

Air↗
PubMed1995

In vitro formation of "urinary stones": generation of spherulites of calcium phosphate in gel and overgrowth with calcium oxalate using a new flow model of crystallization.

Calcium phosphate (CaP) has been detected in the majority of urinary stones containing predominantly calcium oxalate (CaOx). Therefore, crystal phases of CaP might play an important role with respect to the formation of urinary calcium stones in general. Very often, CaP found in stones or tissue of human kidney occurs in the shape of small spherulites. In this paper, we report on a new flow model of crystallization (FMCG), which has been used to generate spherulites of CaP in a gel matrix of 1% agar-agar at 37 degrees C from a supersaturated, metastable solution continuously flowing over the gel surface. Scanning electron microscopy (SEM), X-ray diffraction and microscopic Fourier transformed infrared spectroscopy (FTIR) revealed that the particles formed (diameter: up to 200 microns) consisted of a poorly crystalline core of carbonatoapatite which was partly surrounded by a well-crystallized shell of octacalcium phosphate (OCP) showing radially oriented sheet-like structures. Subsequently, CaOx was grown on these spherulites from a flow of a correspondingly supersaturated solution conducted over the gel matrix. It could be shown by SEM that growth of calcium oxalate monohydrate (COM) was characteristically induced by the OCP shell. Radial sheet-like forms of OCP were directly continued by COM showing a certain radial orientation. The model of crystallization in gel matrices applied here should be well-suited to simulate the process of urinary stone formation under in vitro conditions.

Calcium Oxalate↗
PubMed1994

The scanning force microscopy of DNA in air and in n-propanol using new spreading agents.

We present recent advances in DNA specimen preparation technique for scanning force microscopy (SFM) based on spreading on mica in the presence of cationic and non-ionic detergents. Reproducible DNA imaging in air and in n-propanol has been achieved in the presence of the non-ionic detergent 2,4,6-tris(dimethylaminomethyl) phenol (DMP-30) or the cationic detergent cetylpyridinium chloride (CP) in a microdrop containing nanograms of DNA. In an alternative procedure, a microdrop of detergent is applied to the surface just prior to the DNA. Quantitative image analysis yields as the apparent molecular dimensions of the DNA a width of approximately 7 nm and a height of approximately 0.7 nm, and delineates the problems of DNA metrology by SFM.

1-Propanol↗
PubMed1994

Probing specific molecular conformations with the scanning force microscope. Complexes of plasmid DNA and anti-Z-DNA antibodies.

An anti-Z-DNA IgG antibody was used to probe for the left-handed Z-DNA conformation of a d(CG)11 insert in a negatively supercoiled plasmid DNA (pAN022). The complexes were spread on mica in the presence of a quaternary ammonium detergent benzyldimethylalkylammonium chloride and imaged with a scanning force microscope (SFM). The high affinity anti-Z-DNA antibody was retained even after restriction endonuclease cleavage of the DNA. The two arms in the product molecules had unequal lengths in conformity with the known location of the Z-DNA forming insert. Most complexes exhibited one IgG per DNA molecule. The bound antibodies were up to approximately 35 nm in diameter and extended approximately 2 nm from the mica surface. They were generally in a lateral orientation relative to the DNA, in accordance with prior chemical modification experimental data indicating a bipedal mode of binding for an anti-Z-DNA IgG. However, the SFM images also suggest that the DNA bends to accommodate the two Fab combining regions of the antibody. This study demonstrates the utility of the SFM for investigating conformation-dependent molecular recognition.

Antibodies, Monoclonal↗
PubMed1994

Probing chromatin with the scanning force microscope.

With the scanning force microscope (SFM), one can image the topography of biological material adsorbed at air-solid or liquid-solid interfaces with up to nanometer resolution. In principle, fixation, contrast enhancement, and labeling are not required. We have adapted specimen preparation techniques of conventional electron microscopy for visualizing chromatin ultrastructures in the SFM. A beaded substructure of the nucleoprotein filament was obtained after hypotonic lysis of chicken erythrocytes and air drying. The beads-on-a-string morphology of the basic nucleosomal assembly was well delineated. The nucleosomes appeared as round protrusions with an apparent height of 4-6 nm. The histogram of center-to-center distances between adjacent nucleosome cores along the filament axis had a peak at approximately 30 nm. Reversible changes in the three-dimensional structure were observed upon exposure of air-dried samples of metaphase chromosomes to solutions of different ionic strengths.

Animals↗