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At least 649 records · Page 36Linked to original sources
PubMed2002

Comparison of microinjection (piezo-electric) and cell fusion for nuclear transfer success with different cell types in cattle.

Amongst the many variables that can determine success of cloning, the source of nuclei, the procedure used for nuclear transfer, and the activation of the reconstructed embryo are very important aspects. In this study, we have compared the two most common procedures for transferring nuclei to enucleated oocytes--cell fusion (CF) and piezoelectric microinjection (PEM) using different somatic cells--and we have investigated the effect of different activation procedures. Granulosa cells and fibroblasts were grown to confluency or in low serum to induce a quiescent state, while lymphocytes were thawed immediately prior to use. Enucleated oocytes were reconstructed either with CF or PME by 21-23 h postmaturation. For cell fusion, one pulse of 1 kVolt/cm for 30 microsec was used; for PEM, the cell membrane was broken by repeated pipetting and transferred in a 12% PVP solution to facilitate injection. Manipulated oocytes were activated with ionomycin and cycloheximide (CHX) or 6-DMAP (DMAP) and cultured in microdrops of SOF-BSA-AA. On day 7 (day 0: nuclear transfer), embryo development was evaluated and embryos were either transferred fresh or were frozen. More embryos were successfully reconstructed with PEM than CF, but a higher number of reconstructed embryos by CF developed to blastocyst at D + 7. In addition, in both systems more embryos were obtained after activation with DMAP than with CHX. The transfer of 141 embryos to recipients resulted in a pregnancy rate of 50%, and no differences were observed between the source of donor cell, the reconstruction methods, or the activation protocol. Six calves were delivered at term, and four survived. High pregnancy losses were observed throughout the gestation period.

Animals↗
PubMed2004

Automated calibration of TECAN genesis liquid handling workstation utilizing an online balance and density meter.

With robotics widely used in bioanalytical assays, accurate system performance is essential to ensure the quality and productivity of the robotics. In our lab, an automated calibration procedure has been developed to evaluate the precision and accuracy of the TECAN (Research Triangle Park, NC, U.S.A.) Genesis liquid handling system in a bioanalytical laboratory setting. The calibrations were performed by transferring and weighing the solvents automatically on a microbalance controlled by a Gemini program. From the data acquired, calibration reports were generated using a template. The novel aspect of this approach is the use of an on-line balance and a density meter, both of which combine to make the calibration process simple, efficient, and precise. For quantitative bioanalysis, a variety of solvents, including methanol, water, mixed solvents, and plasma, are typically used to prepare standards and unknown samples. Density information is usually unknown for the mixed solvents, and the density of plasma can vary from species to species. However, with the use of a universal density meter, the density could be obtained in seconds. The issue of solvent evaporation during the calibration process was also addressed. Calibration curves were set up for various liquid classes. Pipetting volumes ranged from 10 microL to 900 microL. Precision and accuracy results obtained from the semiannual performance evaluations showed this procedure to be reliable and user-friendly. Using the automated calibration procedure, the calibration and performance evaluation of the robotic system is considerably more efficient, and the incidence of unacceptable precision and accuracy is greatly reduced.

Automation↗
PubMed2006

Characterization of a novel polymeric scaffold for potential application in tendon/ligament tissue engineering.

Unlike braided fabrics, knitted scaffolds have been proven to favor deposition of collagenous connective tissue matrix, which is crucial for tendon/ligament reconstruction. But cell seeding of such scaffolds often requires a gel system, which is unstable in a dynamic situation, especially in the knee joint. This study developed a novel, biodegradable nano-microfibrous polymer scaffold by electrospinning PLGA nanofibers onto a knitted PLGA scaffold in order to provide a large biomimetic surface for cell attachment. Porcine bone marrow stromal cells were seeded onto either the novel scaffolds by pipetting a cell suspension (Group I) or the knitted PLGA scaffolds by immobilizing in fibrin gel (Group II). Cell attachment at 36 hours, cell proliferation and extracellular matrix synthesis at 1 week, and mechanical properties over 2 weeks were investigated. Cell attachment was comparable and cell proliferation was faster in Group I. Moreover, cellular function was more actively exhibited in Group I, as evident by the higher expression of collagen I, decorin, and biglycan genes. Thus, this novel scaffold, facilitating cell seeding and promoting cell proliferation, function, and differentiation, could be applied with promise in tissue engineering of tendon/ligament.

Animals↗
PubMed1998

Isolation and contraction of the stress fiber.

Stress fibers were isolated from cultured human foreskin fibroblasts and bovine endothelial cells, and their contraction was demonstrated in vitro. Cells in culture dishes were first treated with a low-ionic-strength extraction solution and then further extracted using detergents. With gentle washes by pipetting, the nucleus and the apical part of cells were removed. The material on the culture dish was scraped, and the freed material was forced through a hypodermic needle and fractionated by sucrose gradient centrifugation. Isolated, free-floating stress fibers stained brightly with fluorescently labeled phalloidin. When stained with anti-alpha-actinin or anti-myosin, isolated stress fibers showed banded staining patterns. By electron microscopy, they consisted of bundles of microfilaments, and electron-dense areas were associated with them in a semiperiodic manner. By negative staining, isolated stress fibers often exhibited gentle twisting of microfilament bundles. Focal adhesion-associated proteins were also detected in the isolated stress fiber by both immunocytochemical and biochemical means. In the presence of Mg-ATP, isolated stress fibers shortened, on the average, to 23% of the initial length. The maximum velocity of shortening was several micrometers per second. Polystyrene beads on shortening isolated stress fibers rotated, indicating spiral contraction of stress fibers. Myosin regulatory light chain phosphorylation was detected in contracting stress fibers, and a myosin light chain kinase inhibitor, KT5926, inhibited isolated stress fiber contraction. Our study demonstrates that stress fibers can be isolated with no apparent loss of morphological features and that they are truly contractile organelle.

Actin Cytoskeleton↗
PubMed1995

Adaptation of a functional assay for protein S to a Cobas Fara II centrifugal analyzer.

An adaptation of the manual Staclot protein S functional assay (American Bioproducts, Parsippany, NJ) for the Cobas FARA II centrifugal analyzer is described. This automated method is based on determining the clotting time by measuring the change in turbidity of the specimen as clotting progresses. The accurate and precise pipetting of the analyzer combined with its enhanced data acquisition and rapid parallel processing features result in a markedly improved procedure compared to the less accurate and reproducible manual method. The assay is linear over the range of protein S concentrations encountered clinically (0% to 150%); has a limit of detection of 3% protein S; within and between day precision (CV) at a level of 50% protein S is 4.7 and 12.6%, respectively; and results agree closely with those obtained on the STA automated hemostasis analyzer (slope = 0.98, intercept 3.92, and r = 0.98). Protein S values obtained with this assay for specimens from 20 normal males and 20 normal females were 115% +/- 22.31% (mean +/- standard deviation [SD]) and 98% +/- 18.2%, respectively. In 14 patients on chronic stable treatment with Coumadin (DuPont Pharmaceuticals, Wilmington, DE) the mean functional protein S activity was 16.2% and the SD 11.7%. The method for determination of protein S activity on the centrifugal analyzer yields results comparable to data reported with a variety of other techniques.

Anticoagulants↗
PubMed1980

An improved clinical assay for antithrombin III (heparin cofactor).

A method for determining antithrombin-III heparin cofactor activity that requires no defibrinogenation of plasma, can be used with heparinized samples, and is specific for antithrombin-III heparin cofactor activity was developed. The procedure requires minimal pipetting, uses small amounts of sample over a single short incubation period, and is relatively inexpensive. The antithrombin-III assay appears to be superior to other commercially available procedures when employed in the diagnosis of deficiencies and in the identification of decreased levels of antithrombin III associated with liver disease and thrombotic disorders.

Antithrombin III↗
PubMed1983

Evaluation of the Abbott TDx for the stat measurement of phenobarbital, phenytoin, carbamazepine, and theophylline.

The Abbott TDx is a fully automated method for drug-level monitoring. The system consists of a competitive fluorescence polarization immunoassay performed by a microprocessor-controlled fluorometer with integral pipetting and data reduction systems. We evaluated the method for the stat measurement of phenobarbital (PHENO), phenytoin (PTN), carbamazepine (CARB), and theophylline (THEO). The threshold of detection is PHENO, 0.8 mg/L; PTN, 0.8 mg/L; CARB, 0.1 mg/L; and THEO, 0.4 mg/L. Between-run precision in the therapeutic range expressed as coefficient of variation is between 3.3% and 9.1% for all four drugs. Recovery of each drug from a variety of matrices was essentially 100%, with no significant interference by elevated levels of bilirubin, triglycerides, or hemoglobin. The TDx methods were correlated to established methods for 100 patient specimens: PHENO: Y(TDx) = 0.95 (GLC) + 1.4 mg/L R = 0.98 PTN: Y(TDx) = 0.91 (GLC) + 1.1 mg/L R = 0.99 CARB: Y(TDx) = 0.91 (EMIT) + 0.4 mg/L R = 0.98 THEO: Y(TDx) = 0.93 (HPLC) + 0.5 mg/L R = 0.99 The calibration stability is no shorter than one week (PTN) and as long as five weeks (CARB). The analytic system is an accurate, precise, and highly stable method for the stat measurement of these four drugs.

Anticonvulsants↗
PubMed1983

The temperature control system of the Cobas-Bio centrifugal analyzer.

The temperature control system of the Cobas-Bio centrifugal analyzer (Roche Analytical Instruments, Montclair, NJ) was evaluated using a calibrated thermistor probe and a solution of cresol red in tris buffer as an "optical thermometer" to measure the temperature of the cuvette contents during operation. The instrument accurately achieves a set temperature of 30 degrees C or 37 degrees C, within thermistor readability of 0.13 degrees C, and maintains that temperature within +/- 0.05 to 0.08 degrees C for at least 18 minutes. There is negligible temperature difference between cuvettes in a rotor during operation. After pipetting samples and reagents into the rotor, 1.5 minutes at 30 degrees C and 2 minutes at 37 degrees C are required to bring the cuvette contents within 0.1 degree C of the set temperature. If a second reagent representing 10% of the total volume is added to cuvettes that have been preincubated at the set temperature, up to 1.5 minutes at 30 degrees C and 2 minutes at 37 degrees C are required to reach temperature equilibrium.

Centrifugation↗
PubMed1987

Rapid identification of Staphylococcus epidermidis.

A panel of Minitek sugar disks, consisting of trehalose, mannitol, xylose, and sucrose, was evaluated for its ability to identify blood culture isolates of Staphylococcus epidermidis (SE). Using a heavy suspension of organism in Mueller-Hinton broth, 50 microL was pipetted onto each disk in wells of a flat-bottomed microtiter tray. The tray was covered, incubated in a moist chamber in non-CO2 at 35 degrees C, and examined after 5 and 24 hours. A color change of yellow or orange was positive; no color change (red) was negative. Expected reactions for SE were as follows: negative trehalose, mannitol, and xylose; positive, sucrose. On evaluation of 227 coagulase-negative staphylococci (CNS) at 5 and 24 hours, the panel had a sensitivity of 94 and 96%, specificity of 92 and 89%, predictive value of positive tests of 97 and 96%, and predictive value of negative tests of 84 and 87%. This panel offered an inexpensive and convenient method for differentiating SE from the other CNS in five hours.

Alkaline Phosphatase↗
PubMed2005

Formulation and efficacy of triamcinolone acetonide mouthwash for treating oral lichen planus.

PURPOSE: The stability of a triamcinolone acetonide mouthwash and its efficacy in treating oral lichen planus are described. METHODS: The solubility of triamcinolone acetonide in ethanol, propylene glycol, and glycerin was determined by shaking and equilibrating an excess of triamcinolone acetonide with the solvents for 72 hours. All three solvents were used in formulating a mouthwash. A stock solution of triamcinolone acetonide standard was prepared in ethanol and diluted to yield concentrations of 2, 4, 8, 12, and 16 microg/mL. Analytical sample solutions were prepared by pipetting 0.1 mL of triamcinolone acetonide mouthwash into 10-mL volumetric flasks and diluting to volume with the mobile phase. Accelerated stability studies were conducted by storing the samples in 60-mL amber glass bottles at 45, 60, 70, and 80 degrees C and 75% relative humidity until the triamcinolone concentration decreased markedly. Efficacy was tested by 20 subjects with a clinical diagnosis of and histologically confirmed symptomatic oral lichen planus who were randomized to use the mouthwash (n = 11) or the commercially available triamcinolone acetonide paste (n = 9). RESULTS: The mouthwash had a satisfactory shelf life and was well accepted by patients. Ten of 11 patients treated with the mouthwash for four weeks reported a positive response, and a complete response in signs and symptoms occurred in 4 and 5 of 11 patients, respectively. No significant difference in clinical improvement was observed between groups. CONCLUSION: A triamcinolone acetonide mouthwash had a satisfactory shelf life and was well accepted by patients. It did not have a significantly different therapeutic efficacy from the commercial paste dosage form in the treatment of oral lichen planus.

Adult↗
PubMed1990

32P-postlabeling assay for carcinogen-DNA adducts: description of beta shielding apparatus and semi-automatic spotting and washing devices that facilitate the handling of multiple samples.

The utilization of the 32P-postlabeling assay in combination with TLC for the sensitive detection and estimation of aromatic DNA adducts has been increasing in the past few years. The procedure consists of 32P-labeling of carcinogen-adducted 3'-nucleotides in the DNA digests using [gamma-32P]ATP and polynucleotide kinase, separation of 32P-labeled adducts by TLC, and their detection by autoradiography. During both 32P-labeling and initial phases of TLC, a relatively high amount of [gamma-32P]ATP (3.0-4.5 mCi) is handled when 30 samples are processed simultaneously. We describe the design of acrylic shielding apparatus, semi-automatic TLC spotting devices, and devices for development and washing of multiple TLC plates, which not only provide substantial protection from exposure to 32P beta radiation, but also allow quick and easy handling of a large number of samples, thus expediting the assay workup and making it less labor-intensive. Specifically, the equipment includes: (i) a multi-tube carousel rack (7.5 cm diameter and 7.7 cm height) having 15 wells to hold capless Eppendorf tubes (0.5 ml) and a rotatable lid with an aperture to access individual tubes; (ii) a pipet shielder; (iii) two semi-automatic spotting devices to apply radioactive solutions to TLC plates; (iv) a multi-plate holder for TLC plates; and (v) a mechanical device for washing multiple TLC plates. Item (i) is small enough to be held in one-hand, vortexed, and centrifuged to mix the solutions in each tube while beta radiation is shielded. Items (iii) to (iv) aid in the automation of the assay.

Carcinogenicity Tests↗
PubMed1992

A simple, sensitive assay to detect DNA-protein crosslinks in intact cells and in vivo.

Addition of potassium chloride to sodium dodecyl sulfate (SDS) resulted in the formation of an insoluble precipitate that was easily recovered by low-speed centrifugation. Since SDS tightly binds to proteins but not DNA, all proteins and detergent-resistant DNA--protein complexes were also effectively co-precipitated in the presence of potassium--SDS leaving free DNA in the supernatant. The amount of SDS-precipitable DNA represented a measure of DNA--protein crosslinks. We have adapted this method for determining DNA--protein crosslinks formed in cells following their exposure in culture or in vivo to crosslinking agents such as chromate, cis-Pt(II) diammine dichloride and formaldehyde. The critical parameters for application of the K--SDS assay to cells were rigorously reproducible shearing of chromosomal DNA and effective washing steps. We have found that freeze-thawing SDS lysed cells followed by vortexing and repeated resuspensions of the precipitate by pipeting resulted in a low background and high reproducibility of the assay. The method detected in a dose-dependent manner DNA--protein crosslinks induced in CHO cells by chromate, cis-platinum and formaldehyde, with sensitivity similar to the alkaline elution procedure. The K--SDS assay was also successfully utilized to determine DNA--protein crosslinks in rat and mouse white blood cells exposed in vivo to chromate. Its sensitivity and simplicity in sample handling and DNA--protein complex isolation potential allows wide application of the assay to measure formation of DNA--protein crosslinks. The ease of recovery of DNA--protein complexes allows for a more thorough investigation of this lesion.

Animals↗
PubMed2000

Characterization and identification of (CT)n microsatellites in soybean using sheared genomic libraries.

Three small insert (300 to approximately 600 bp) sheared genomic libraries were constructed by pipetting and DNase I treatment of soybean DNA. About 15,000 clones from each library were screened for CT- simple sequence repeats (CT-SSRs). The CT-SSRs were abundant in the soybean genome at an estimated frequency of approximately one SSR per 110 kb of genomic DNA. Following the sequencing of 129 positive clones, the repeat types and frequency of CT repeats among the positive clones were characterized. Forty-nine primer pairs were designed and preliminarily evaluated for their ability to amplify genomic DNA from a set of six varieties, including parents of a mapping family. Amplified products were analyzed by 10% PAGE. Eighty-eight percent of the designed primers were able to amplify all these genomic DNAs using a single PCR profile of 53 degrees C annealing temperature, of which 22 (45%) were polymorphic in the six varieties, and 14 of them were polymorphic in the parents of the mapping family. The polymorphic primer sets were further assessed for allelic information using DNA from 16 soybean cultivars. The average number of alleles was 4, ranging from 2 to 7 with the highest polymorphism information content value 0.84. Fourteen of these SSRs were mapped, using an existing soybean RFLP map. The findings presented here will advance our understanding of the soybean genome, and assist in the mapping genome and discrimination of closely related varieties of this species.

Chromosome Mapping↗
PubMed1997

Effects of different hyaluronidase concentrations and mechanical procedures for cumulus cell removal on the outcome of intracytoplasmic sperm injection.

The aim of this study was to compare concentrations of hyaluronidase and mechanical methods used to denude human oocytes from surrounding cumulus and corona cells prior to intracytoplasmic sperm injection (ICSI). Cumulus and corona cells were removed in two pipetting steps: first in a medium containing hyaluronidase, and then in a medium without enzyme. The first step in the procedure was investigated. Different hyaluronidase concentrations (78, 39 or 10 IU/ml) and pipettes of different size (inner diameter 250 or > 1000 microm) were used to remove the cumulus cells. The time required to denude the oocytes was recorded. Metaphase II oocytes were injected, and the survival, fertilization, embryo development and pregnancy rates were evaluated. We found that by using a pipette with an inner diameter of at least 1000 microm we were able to decrease significantly the time an oocyte is exposed to hyaluronidase, even if the concentration of enzyme is very low (10 IU/ml). For the different conditions there was no statistically significant effect on the outcome in terms of survival, normal fertilization [two pronuclear (2PN)], parthenogenetic activation (1PN), abnormal fertilization (3PN), embryo development and pregnancy rates after ICSI. In conclusion, a concentration as low as 10 IU/ml hyaluronidase in combination with a pipette of at least 1000 microm inner diameter can be used successfully to denude oocytes for microinjection.

Cytological Techniques↗
PubMed1997

Cumulus cells are required for the increased apoptotic potential in oocytes of aged mice.

Recent studies with female ICR mice have suggested that oocyte DNA fragmentation is one reason for poor oocyte quality and lower fertility associated with ageing. Since it was not determined if this increased 'apoptotic' potential in aged oocytes is due to changes within the oocyte itself or within the microenvironment of cumulus cells (CC) surrounding the germ cell, we sought to clarify if CC were required to affect the rate of apoptosis in oocytes maintained in vitro. Intact cumulus-oocyte complexes (COC) were retrieved by superovulation of virgin female ICR mice at 7 weeks ('young') or 34-35 weeks ('aged') of age. One-half of the COC in each group were incubated at 37 degrees C in human tubal fluid medium under paraffin oil for 24 h. The other half of the COC in each group were denuded of CC and incubated under the same conditions (denuded oocytes; DO). Following incubation, COC were stripped of adherent CC by gentle pipetting. All DO were then fixed and checked by light microscopy for morphological changes characteristic of apoptosis. In young mice, the presence of CC had no significant effect on oocyte death rate (18 +/- 9% and 14 +/- 6% apoptotic oocytes in COC and DO, respectively; P > 0.05). However, in aged mice the percentage of CC-enclosed oocytes that underwent apoptosis was significantly greater as compared to the death rate in DO (48 +/- 3% versus 19 +/- 8% apoptotic oocytes, respectively; P < 0.05). This increased death potential was due to the presence of CC since the occurrence of apoptosis in DO of aged versus young mice was not significantly different (19 +/- 8% versus 14 +/- 6% apoptotic oocytes, respectively; P > 0.05). These results demonstrate that the age-dependent acceleration of apoptosis in oocytes maintained in vitro requires the CC.

Aging↗
PubMedDate not supplied

Infections in IVF: review and guidelines.

Since the inception of in-vitro fertilization (IVF), questions about contamination and the transmission of infection have been raised. In this review, screening for Chlamydia trachomatis, as well as medical and ethical considerations on IVF in couples infected with hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV), are discussed. IVF is not contraindicated in case of HBV or HCV infection, but the decision is far more delicate in case of HIV infection. If donor gametes or embryos are used, prevention of infectious disease transmission resides in accurate donor selection, including screening for C. trachomatis, HIV, HBV, cytomegalovirus and Treponema pallidum. In the embryology laboratory, microbial contamination of the IVF system deserves attention, and can be prevented by using sterile technique and supplementing culture media with screened sera or serum substitutes and antibiotics. Persons whose biological material is to be cryopreserved should be screened for HBV, HCV and HIV, and separate containers should be used for infected and non-infected material. Finally, transmission of infectious diseases to laboratory personnel can be prevented by adherence to strict safety guidelines, wearing of protective clothing, HBV vaccination, prohibition of mouth pipetting, and developing a plan for the disposal of bio-hazardous material.

Chlamydia Infections↗
PubMed1979

Transmission of hepatitis B virus in clinical laboratory areas.

The transmission of hepatitis B virus (HBV) in clinical laboratory areas was delineated by the use of hepatitis B surface antigen (HBsAg) as presumptive evidence for the presence of the infective agent. Twenty-six (34%) of 76 environmental surfaces sampled were positive for HBsAg. The outer surfaces of blood- and serum-specimen containers had HBsAg contamination rates of 55% (six of 11) and 44% (four of nine), respectively. Subsequent handling of pipetting aids, marking devices, and other items led to their contamination and further dissemination of HBsAg. An assay instrument for complete determinations of blood cell counts was observed to splatter and drip blood during its operation. The contamination rate for environmental surfaces associated with this instrument was 15%. The data indicate that transmission of HBV in the clinical laboratory is subtle and mainly via hand contact with contaminated items during the various steps of blood processing. These data support the concept that the portal of entry of HBV is through inapparent breaks in skin and mucous membranes.

Blood Specimen Collection↗
PubMedDate not supplied

Whole blood deproteinization for drug screening using automatic pipettors.

Automating the initial screening of postmortem blood and other tissues for drugs of abuse requires a pipetting procedure that is compatible with immunoassay screening tests. The deproteinization procedure uses a zinc sulfate-5-sulfosalicylic acid reagent to precipitate blood proteins. This procedure for deproteinization of whole blood and tissue homogenates is compatible with coated tube radioimmunoassays (RIA) and can therefore be used in automating the initial screening step.

Automation↗