Search PubMed⌕ Search

Biomedical subjects

B Schaffer

Publications and source records attributed to B Schaffer.

At least 19 recordsLinked to original sources
PubMed2005

Scripting-customized microscopy tools for Digital Micrograph.

Software is an integral part of all electron microscopy systems, encompassing hardware control, data acquisition and processing. It is unlikely that any one software system will meet all the requirements of experienced users. However, if the software supports custom scripting, then users are well placed to address any shortcomings by writing their own software. In this paper, we highlight the scripting capability within Gatan Inc.'s Digital Micrograph (DM) software, a widely used program for TEM imaging and EELS spectroscopy. We show how scripting can greatly extend the capabilities of the DM software, in tasks ranging in complexity from simple image manipulation through to full-blown microscope/imaging filter control and data acquisition. Scripting enables customized software tools to be developed to meet individual experimental needs, something which no software manufacturer could ever hope to do on a commercial basis. In essence, scripting allows the microscopist to drive the software rather than the software drive the microscopist. To foster an increased awareness and interest in DM scripting we have developed a web-based archive for DM scripts, which is freely accessible via the internet.

Journal Article↗
PubMed2003

Gene structure and alternative splicing of glycogen synthase kinase 3 beta (GSK-3beta) in neural and non-neural tissues.

Glycogen synthase kinase 3 beta (GSK-3beta) is a multifaceted serine-threonine kinase that is of interest both because of its role in the canonical Wnt signaling pathway, which is involved in mammalian brain regionalization, and its role in phosphorylating the microtubule-associated protein Tau. Because of the potential association of GSK-3beta with human developmental and neurodegenerative conditions, we determined its exon/intron boundaries by a combination of sequencing, polymerase chain reaction (PCR) and database mining. Study of GSK-3beta expression using reverse transcription-PCR, Western blotting and Northern blotting showed alternative splicing in nervous and non-nervous system tissues. Both at the protein and mRNA level we were able to identify two isoforms, one full length form containing exon 10 and one without exon 10. At the mRNA level we identified an additional exon that is sometimes seen between exons 8 and 9. Furthermore, rather than the reported 2-3 kb mRNA predominant in non-neural tissues, we identified the major brain isoforms of GSK-3beta as two high molecular weight RNAs (8.4 and 7.7 kb).

Alternative Splicing↗
PubMed2000

[The Dresden Cord Blood Bank. Experiences of the Cord Blood Bank in Dresden, promoted by the German bone Marrow Donor Registry].

BACKGROUND: Allogeneic bone marrow and peripheral blood stem cell transplantation is the treatment of choice for a number of malignant hematological diseases, marrow failure syndromes and severe congenital immunodeficiency states. As a new, valuable source of hematopoietic stem cells, cord blood has become increasingly attractive to the medical community. More than 1500 related and unrelated cord blood transplantations have already been performed worldwide. Cord blood can be a particularly good alternative source of stem cells for pediatric patients, if no HLA-identical donor can be found. MATERIAL AND METHODS: In August 1997 the Cord Blood Bank at the University Hospital of Dresden initiated the collection, processing and cryopreservation of placental blood. This Cord Blood bank is promoted by the German bone marrow donor registry DKMS in Tübingen/Germany collaborating with 8 gynecological clinics in Dresden, Bautzen and Erlabrunn. Before cryopreservation, volume reduction of cord blood units is routinely performed by centrifugation and by separation of the buffy coat. RESULTS: As of March 2000, more than 2200 cord blood units have been collected. 60% of the samples had to be discarded because of insufficient quality (low volume and/or cell count, bacterial contamination, positive infectious disease markers). However, more than 800 cord blood units met all quality control criteria and were cryopreserved. CONCLUSION: These data from the Cord Blood Bank at the University Hospital of Dresden are comparable with results from other cord blood banks. Efforts directed toward the cryopreservation and banking of increased numbers of cord blood units are being continued worldwide and should be supported by the general public.

Blood Banks↗
PubMed2000

Citrus leafminer (Lepidoptera: Gracillariidae) density: effect on yield of 'Tahiti' lime.

The relationship between damage by citrus leafminer, Phyllocnistis citrella Stainton, and 'Tahiti' lime yield were investigated in a 15-yr-old and a 5-yr-old lime orchard. Citrus leafminer population densities were controlled by insecticide applications of abamectin plus FC 435 oil, abamectin plus FC435 oil plus imidacloprid, and methomyl. The control was not treated. To ensure adequate citrus leafminer densities, adult citrus leafminer were periodically released in the experimental plots during fall and winter. For the 15-yr-old trees, the least amount of leaf area damage occurred in the abamectin plus FC 435 oil plus imidacloprid (1.9%) and the abamectin plus FC435 oil (2.3%) treatments compared with the control treatment (10-21%). In the 5-yr-old orchard, the least amount of leaf area damaged occurred in the abamectin plus FC 435 oil plus imidacloprid (0.4%) and the imidacloprid (0.1%) treatments compared with the control (20.85%). The percentage of leaf area damaged was linearly correlated with the average number of mines per leaf, average mine days, and cumulative mine days in both orchards. In both orchards, the percentage of leaf area damaged and cumulative mine days was linearly correlated with the number of fruit per tree and total fruit weight per tree. Calculating the economic injury levels indicated that 16-23% and 18-85% of leaf area damaged caused significant yield reductions in 15-yr-old and 5-yr-old trees, respectively.

Animals↗
PubMed1999

Defining optimum conditions for the ex vivo expansion of human umbilical cord blood cells. Influences of progenitor enrichment, interference with feeder layers, early-acting cytokines and agitation of culture vessels.

Ex vivo expansion of human umbilical cord blood cells (HUCBC) is explored by several investigators to enhance the repopulating potential of HUCBC. We performed experiments using either Ficoll-separated or CD34+-selected HUCBC from the same donation in serum-free medium. CD34-purified HUCBC were cultured on either human umbilical vein endothelial cells (HUVEC) or irradiated bone marrow-derived stroma cells (BMSC) with addition of different cytokines. In addition, we tested the expansion of HUCBC in culture vessels with continuous rotation. CD34 enrichment led to a significant increase in the expansion factor of CD34+ cells compared with unmanipulated HUCBC. BMSC were more efficient in amplifying early progenitors than HUVEC. Optimum results were reached by a combination of SCF, FLT-3L at 300 ng/ml and IL-3 at 50 ng/ml. No significant improvement in the expansion of CD34+/38- primitive progenitors could be obtained with other combinations. Addition of megakaryocyte-derived growth and development factor to each growth factor cocktail improved the expansion results. Continuous rotation of culture vessels did not ameliorate the expansion rate of the analyzed subsets. Culture conditions separating stroma and HUCBC by a semipermeable membrane improved the expansion factors of CD34+, CD34+/38-, and CD34+/41+ cells and CFU-GM compared with contact cultures. These data might be useful when designing culture systems for clinical scale ex vivo expansion of HUCBC.

Antigens, CD34↗
PubMed1999

Experiences of the Dresdner Cord Blood Bank, supported by the Deutsche Knochenmarkspenderdatei.

Allogeneic bone marrow and peripheral blood stem cell transplantation is the treatment of choice for some malignant hematologic diseases, marrow failure syndromes, and severe congenital immunodeficiency states. Since Gluckman et al reported in 1988 the first successful human leukocyte antigen (HLA)-matched sibling umbilical cord blood stem cell transplantation, it has been known that cord blood is a valuable source of hematopoietic stem cells. The Cord Blood Bank at the University Hospital of Dresden was founded in 1997 and started collecting, processing, and cryoconserving umbilical cord blood in August 1997. The cord blood bank is supported by the largest German donor registry: Deutsche Knochenmarkspenderdatei (DKMS) in Tubingen, Germany. With the informed consent of the mothers, the collection is performed in collaboration with six hospitals in Dresden, Berlin, and Bautzen. We routinely perform a volume reduction by centrifuging the blood bag and expressing the leukocyte-rich supernatant. Routinely, sterility, total nucleated cells (TNC), CD34+ cell count, HLA class I and II, ABO/Rh blood group, and colony-forming units are evaluated. The maternal blood is screened for anti-immunodeficiency virus (anti-HIV), anti-hepatitis C virus (anti-HCV), anti-hepatitis B surface antigen (HBsAg), anti-hepatitis B surface (anti-HBs), anti-hepatitis B core (anti-HBc), anticytomegalovirus (anti-CMV), and toxoplasmosis and with Treponema pallidum hemagglutination assay (TPHA). More than 1,000 cord blood units could be collected. Because of the required volume and cell count and because of sterility, 50% of the collected units had to be discharged. Our results are comparable with data of other cord blood banks: mean volume 79 mL; cell count after volume reduction-TNC, 7.16 x 10(8); mononucleated cells (MNC), 3.75 x 10(8); CD34+ cells, 1.95 x 10(6); colony-forming units (CFU), 67.1 x 10(4). To increase the pool of potential umbilical cord blood units and in order to evaluate the possibility for unrelated transplants, cryopreservation and banking of large numbers of cord bloods are necessary.

Animals↗
PubMed1998

Molecular approaches to diagnosis of pulmonary diseases due to Mycoplasma pneumoniae.

In this prospective study, the use of a culture-enhanced PCR assay for the detection of Mycoplasma pneumoniae, followed by hybridization with a specific probe (MP-HPCR) or without hybridization (MP-PCR), and the use of a nested PCR (MP-NPCR) were evaluated. Clinical samples (190 specimens) from 190 patients with respiratory complaints were incubated in culture broth overnight and then subjected to PCR. The results of the PCR were compared to those obtained by culture, the direct antigen test, and serologic testing by microparticle agglutination and by immunoblotting in unclear cases. The sensitivities were 19 CFU for MP-PCR, 1.9 CFU for MP-HPCR, and 0.019 CFU for MP-NPCR. PCR amplification of the beta-globin gene was possible in 98% of cases: after dilution of the beta-globin-negative samples, all samples were reactive. Correlation between negative MP-NPCR results and negative serology results was found in 89% of cases; a positive correlation was found with 10% of the patients. Samples from three immunocompromised patients were MP-NPCR positive but serologically negative. High respiratory colonization by M. pneumoniae (>10(5) CFU/ml) in patients with acute respiratory disease could be detected by culture, MP-PCR, and MP-NPCR. These results indicate that MP-PCR and MP-NPCR are reliable methods for the detection of M. pneumoniae in respiratory tract samples of patients with respiratory complaints.

Adult↗
PubMed1994

Partitioning of photoassimilates in avocado (Persea americana Mill.) during flowering and fruit set.

To assess competition for photoassimilates among developing inflorescences, fruitlets and vegetative shoots in avocado (Persea americana Mill.), the distribution of recent photoassimilates was examined before and during flowering, fruit set, and the transition from sink to source of developing vegetative shoots. Mature leaves, located proximal to developing reproductive organs, and developing leaves, located distal to those organs, were exposed to a one-hour pulse of (14)CO(2). Translocation of radiolabeled assimilates was monitored over time and among organs. Overall distribution of assimilates was dependent on dry mass of tissues regardless of organ type. Flowers and fruitlets did not demonstrate greater sink strength than non-autotrophic leaves. Organs receiving assimilates were in phyllotactic alignment with source leaves. Photoassimilates were never limiting, although flower and fruitlet abscission occurred during and long after this competitive period. Carbohydrate availability was sufficient to support the growth of both developing fruitlets and leaves during early stages of reproductive development, and it did not limit fruitlet growth or stimulate fruitlet abscission.

Journal Article↗
PubMed1993

MR imaging of slow axonal transport in vivo.

Three magnetopharmaceuticals based on a monocrystalline iron oxide nanocompound (MION) are evaluated as potential contrast agents for demonstrating axonal transport in vivo by magnetic resonance (MR) imaging. One agent has a strong positive charge, one has a strong negative charge, and the third is covalently linked to wheat germ agglutinin, a plant lectin with a high affinity for axon terminals. All three agents were tagged with rhodamine, and fluorescence microscopy was used to determine their fate after administration and to validate the imaging results. Following injection into or near various neural structures in the motor and visual systems of rats, MR images were obtained at multiple times up to 11 days later, and the imaged tissues were processed for subsequent histological examination. Similar results were obtained with all three agents. Axonal transport was not seen by MR imaging or fluorescence microscopy when the agents were injected into the calf muscles, the vitreous of the eye, or the superior colliculus. However, bidirectional axonal transport was shown unequivocally by both methods after injection directly into the site of a focal crush injury to the sciatic nerve. The nerve, which otherwise is isointense with surrounding tissues on MR images, appeared as a uniformly hypointense structure having a length approximately in proportion to the time from injection to imaging. By 11 days, the course of the nerve was traceable from its component roots in the cauda equina to its bifurcation into the tibial and common peroneal nerves in the leg. A transport rate of about 5 mm/day was calculated, which is consistent with the mechanism of slow transport. MION-based magnetopharmaceuticals thus can be used to demonstrate slow axonal transport, and thereby visualize peripheral nerves, in vivo by MR imaging.

Animals↗
PubMed1992

Carbon dioxide exchange of developing avocado (Persea americana Mill.) fruit.

Net efflux of CO(2) from attached avocado (Persea americana Mill.) fruit was measured periodically from three weeks after anthesis to fruit maturity. Net CO(2) exchange was determined in daylight (light respiration, R(l)) at a photosynthetic photon flux (PPF) greater than 600 micromol m(-1) s(-1), and in the dark (dark respiration, R(d)). Dark respiration and R(l) were highest during the early cell division stage of fruit growth (about 25 and 22 nmol CO(2) g(dw) (-1) s(-1), respectively) and decreased gradually until fruit maturity to about 1 and 0.5 nmol CO(2) nmol CO(2) g(dw) (-1) s(-1), respectively. Fruit photosynthesis, calculated from the difference between R(d) and R(l), ranged from 0.5 to 3.1 nmol CO(2) g(dw) (-1) s(-1). Net rate of CO(2) assimilation on a fruit dry weight basis was highest during the early stages of fruit growth and reached the lowest rate at fruit maturity. Net rate of CO(2) assimilation of fruit exposed to light was 0.4 to 2.5% of that for fully expanded leaves. Although the relative amount of carbon assimilated by the fruit was small compared with the total amount of carbon assimilated by the leaves, the data indicate that avocado fruit contribute to their own carbon requirement by means of CO(2) assimilated in the light.

Journal Article↗
PubMed1989

Use of the childhood autism rating scale with autistic adolescents and adults.

The suitability of the Childhood Autism Rating Scale (CARS) for diagnosing adolescents and adults with autism was tested and CARS ratings over time were examined to assess how the characteristics of autism change during adolescence. Subjects (N = 89) had been rated with the CARS before age 10 and again after age 13. A cutoff score of 27 was used; of 59 diagnosed as autistic prior to age 10, 92% were diagnosed as autistic after age 13. Moreover, 9 CARS categories showed significant improvements over time; only 1 showed a significant decrement. The CARS is thought to be a useful screening device for adolescents and adults with autism. Implications of this research for the understanding of autism and how it changes with development are discussed.

Adolescent↗
PubMed1984

Adolescent prostitution.

Although juvenile prostitution has been documented since antiquity, its rise since 1970 has been overwhelming. Newsweek (1978) reported an alarming increase in arrests of prostitutes under the age of 25 in New York from 24% to 74% in the previous 10 years. In Boston the average age of prostitutes is 20 years old; in Miami it is 18. The purpose of this paper is to explore the conditions which lead to teenagers' becoming prostitutes, and how our institutions and legal system deal with them.

Achievement↗
PubMed1983

Accumulation of bone-scanning agents in hepatoma.

A case of hepatocellular carcinoma demonstrating intense uptake of Tc-99m methylene diphosphonate (MDP) is described. This is one of three cases seen by the authors who suggest that hepatoma be considered along with other previously described entities when there is localized accumulation of a bone-scanning agent in the liver.

Aged↗
PubMed1980

99mTc-MDP uptake in nonosseous lesions.

A strikingly similar, massive, soft-tissue localization of 99mTc-MDP is described in three patients who had tumoral calcinosis, mild-alkali syndrome, and chronic renal failure, respectively. Although the basic mechanism for this phenomenon is unknown, some derangement of calcium and phosphate metabolism was present in all three cases.

Adult↗
PubMed1976

Gastrointestinal complications of aortic bypass surgery.

Gastrointestinal bleeding following abdominal aortic bypass surgery is not uncommon, as approximately 20% of patients with abdominal aortic aneurysms have peptic ulcer disease. We have recently seen three patients who presented with gastrointestinal bleeding secondary to the complications of their surgery. The cause of the bleeding was aortoduodenal fistula, graft erosion into the sigmoid colon and ischaemic colitis respectively. The correct diagnosis was only considered in one patient, although in retrospect it should have been suggested in all three. Our experiences with these complications and their clinical and radiological presentation form the basis for this paper.

Aged↗