Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MICROMANIPULATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources
PubMed1985

How does embryo manipulation fit into present and future pig reproduction?

Available techniques for the collection and direct transplantation of pig embryos are simple and efficient and could be used for the expansion of new lines, for increasing selection pressure in nucleus herds and for extracting healthy stock from a diseased source. However, the reduced viability of pig embryos during culture in vitro and the inability as yet to preserve them by deep-freezing impose limits to the use of embryo transplantation for the export or import of potential breeding stock. The efficiency of breeding schemes could be improved by the sexing of embryos and the possibility of producing genetically identical twins or quadruplets by micromanipulation of embryos should improve the efficiency of animal experimentation. Chimaerism may be used to rescue embryos of a non-viable genotype such as parthenotes or those derived by hybridization, but the greatest revolution in pig breeding may be brought about by the introduction of foreign cloned genes into eggs and the production of transgenic animals. Eggs at an appropriate stage for microinjection may be provided in the future by techniques for the maturation and fertilization of oocytes in vitro. Animal breeders should be aware of the potential impact of techniques for the manipulation of eggs and embryos on future developments in animal production.

Animals↗
PubMed1985

[Experimental study of brain lesions after combined coaxial exposure to high-peaked pulse wave form CO2 and Nd: YAG lasers on the brain].

UNLABELLED: The CO2 laser is useful for cutting and vaporization but not for coagulation and hemostasis. On the contrary, YAG laser is effective for coagulation and hemostasis but not for cutting. The purpose of this study is to examine the effect of the exposure of combined, coaxial CO2 and YAG laser on the animal brain to supplement the advantages and draw-backs of each other. To compare these results, each of non-combined pulse wave form CO2 and YAG lasers was employed separately. MATERIALS AND METHODS: The lasers in this study were pulse wave form CO2 and YAG lasers, employed separately or simultaneously using 130 YZ of Nihon Infrared Industries Company. Japanese white rabbits were anesthetized with pentobarbital. Fronto-parietal burr holes were made, the dura was removed and then Evans blue solution was injected intravenously. The lasers were employed to the cerebral cortex without great vessels using a micromanipulator attached to the operative microscope with a distance of 30 cm. The spot size was 700 mu for CO2 laser and 1200 mu for YAG laser. The first experiment was to see the effect of nine combinations of simultaneous coaxial CO2 of 2, 4 and 8 watts and YAG lasers of 10, 20 and 40 watts, 1 sec on the brain. In the second experiment, also combining two lasers, the exposure time of YAG laser was elongated from 1 or 2 seconds into 2 or 4 seconds and the arrangement of powers was the same as that of the first experiment. The lesions were thus made in 18 different conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

[Physical and technical bases of tumor hemostasis with a CO2 laser in neurosurgery].

The particular thermal properties of CO2 laser make it an useful instrument for neurological surgery. Necrosis and carbonization zones, as well as its thermal diffusion in the nervous tissue are dramatically less important with a CO2-laser unit than with other lasers (Nd-Yag or Argon) and moreover with the electrical mono--or bipolar coagulator. That is why the authors chosed this instrumentation for achieving a good hemostasis. It was particularly useful during removal of intracranial tumors situated close to the functional structures of the basis of the brain and the brainstem. The authors present their experience with the french CO2-laser unit Ercelas 80 (Robert et Carrière Biomedical) that they have been using routinely since 1983 in 60 neurosurgical procedures. They present the technical standards necessary to perform such an hemostasis either with the hand-piece or using the micromanipulator. In all cases the output power must be much lower for hemostasis than for tumoral cutting or vaporization. Depending on the type of tumor, radiation power should vary from 2 to 10 watts if a linear emission is used, and from 10 to 30 watts in case of pulsed emission. On the other hand, CO2-laser beam must be unfocussed so as to avoid cutting the vessels less than 0.5 mm in diameter before coagulating them properly.

Carbon Dioxide↗
PubMed1985

Timing of the initiation of rRNA gene expression and nucleolar formation in cleavage embryos arrested by cytochalasin B and podophyllotoxin and in cytoplasm-extracted embryos of Xenopus laevis.

The timing mechanism of rRNA gene expression was studied in Xenopus laevis embryos whose cleavage was arrested by treatment with cytochalasin B or podophyllotoxin, and in fertilized eggs from which about 40% of the cytoplasm was extracted by micromanipulation. rRNA synthesis was activated in the cleavage-arrested embryos and also in cytoplasm-extracted embryos at the time when the control embryos commenced synthesizing rRNA at the late blastula stage. Formation of the nucleolar structure occurred at the normal time in the nuclei of cleavage embryos arrested by podophyllotoxin. Therefore, neither twelve continuous cell divisions nor the nuclear division which normally precedes the MBT (mid-blastula transition) was the factor determining the timing of rDNA expression. Moreover, lowering of the cytoplasmic:nuclear ratio to a certain threshold level was not a prerequisite for rDNA activation. Some regulatory mechanism dependent on the time elapsed from fertilization is likely to be the important factor permitting rDNA expression.

Animals↗
PubMed1977

[Cells secreting antibodies originate from cells secreting immunoglobulins without a detectable antibody function for the antigen injected].

Cells secreting immunoglobulins without detectable antibody function arising after an injection of horseradish peroxidase were micromanipulated from the center of haemolytic plaques of Sheep red blood cells coated with anti-Ig antibodies. These cells were cultured individually for 48 hrs, with irradiated cells as feeder layer and in the presence of the immunogen and of LPS. It was shown that after this time 22% of the immunoglobulin-secreting cells had generated antiperoxidase antibody-secreting cells or were transformed into antibody-secreting cells.

Animals↗
PubMed1979

Prognosis for the evolution of Ophthalmology: Part II.

This paper represents an application of modern forecasting methods to prognosis in ophthalmology. Using these methods the author considers possible changes in patterns of ocular pathology in the next 20 to 25 years. He also indicates the probable evolution of such methods of investigation as biomicroscopy, ophthalmoscopy, electrophysiology, and automatic diagnosis. In the field of ophthalmosurgery, the author explores the idea of automation of eye surgery and extended use of micromanipulators in surgery. He predicts the autoplasty of the anterior segment and the transplant of the whole eye.

Eye↗
PubMed1976

Single cell studies on the antibody-forming potential of fractionated, hapten-specific B lymphocytes.

This study addresses itself to the problem of antibody formation in vitro by mouse splenic B lymphocytes enriched for reactivity to the hapten NIP by the hapten-gelatine binding and melting technique of Haas and Layton (1975). Small numbers of NIP-gelatine-bound B cells were placed in microcultures either by bulk dispensing of dilute cell suspensions, or by micromanipulation under direct microscopic visualization. Antibody formation was induced by the T cell-independent hapten-protein conjugate NIP-polymierized flagellin, using 10(4) thymus cells per microlitre as 'filler' cells. The frequency of precursors of NIP-specific antibody-forming cells among bound cells was about 2-2 X 10(-2) (one cell in forty-five) by both statistical and direct evaluation, after adjustment for a background frequency of 6-10 X 10(-8) precursors in the thymus filler cells. Single clones commenced antibody secretion asynchronously, as shown by the fact that the incidence of positive cultures continued to rise over the whole three days of culture, and that very small clones of one to four plaque-forming cells (PFC) were still found on day 3. The mean PFC number per positive culture rose from 1-2 at day 1 to 4-7 at day 2 and about 20 at day 3.

Animals↗
PubMed1984

Alloantigen-induced cytotoxicity against syngeneic tumor cells: analysis at the clonal level.

It has been shown that peritoneal exudate cells (PEC) from BALB/c mice immunized with minor histocompatibility antigens presented by DBA/2 or B10.D2 spleen cells are capable of lysing syngeneic YC8 tumor cells in a 4-hr 51Cr-release assay. In this study, we employed limiting dilution analysis to determine the frequency of CTL precursors (CTL-P) reactive against both the specific DBA/2 (or P815) target and the syngeneic tumor YC8. The mean frequency of anti-DBA/2 CTL-P in PEC from BALB/c mice immunized with DBA/2 was 1/302. Between one-third and one-fifth of limiting dilution microcultures that exhibited lytic activity against DBA/2 lymphoblasts (or P815) were also able to lyse YC8. No lysis of YC8 was observed in the absence of a parallel lysis on DBA/2 lymphoblasts or P815 target cells. T cell clones, derived by micromanipulation from microcultures selected for cytotoxic activity against YC8 and/or P815, maintained either the specific anti-allogeneic or the doubly reactive ( antiallogeneic plus anti-syngeneic tumor) phenotype. Fourteen clones (six specific and eight doubly reactive) were tested for cytotoxic activity on a panel of target cells with different haplotypes. All showed H-2-restricted specificity for minor histocompatibility antigens shared by DBA/2 and B10.D2. The restriction element for some of the clones mapped in the K region of the H-2 complex, whereas for other clones the restriction element mapped in the D region; both K- and D-restricted clones were able to lyse YC8. When the clones that exhibited lysis on YC8 were tested on two other BALB/c tumor targets, LSTRA, a Moloney virus induced lymphoma, and RL male-1, a radiation induced lymphoma, two of seven were found to lyse all three syngeneic tumor targets equally well, but not syngeneic BALB/c blasts. These clones were functionally categorized as conventional CTL because they were unable to proliferate when cultured with antigen in the absence of exogenous lymphokines, and were unable to produce lymphokine with IL 2 activity when stimulated by the appropriate splenocytes. When tested in vivo in a Winn assay, a strong anti-tumor activity against YC8 was exerted by the anti-DBA/2 clones DY4 -3 and DY16 -3. These clones lysed both YC8 and the immunizing target cells in vitro. No in vivo effect in neutralizing YC8 tumor growth was observed with clone D2-1, a clone that lysed DBA/2 targets but not YC8 in vitro.

Animals↗
PubMed1983

Macromolecules stimulating human granulocytic colony-forming cells, precursors of these cells, and primitive erythroid progenitors: some apparent nonidentities.

The relationship between molecules having granulocyte colony-stimulating activity (G-CSA), erythroid burst-promoting activity (E-BPA), and activity promoting increase in the number of granulocytic progenitors in liquid culture (delta GPA) was explored in conditioned medium from human leukocytes (HLCM) and human placenta (HPCM). As tested on human hemopoietic progenitors in culture, G-CSA eluted from Sephadex G100 as a single peak with apparent molecular weight of 25,000, separating partially from E-BPA and delta GPA, which both had an apparent molecular weight of 45,000. All three activities eluted together from hydroxyapatite at low molarity phosphate. Their charge properties were also similar and all three electrofocused in flat gel beds in the pH range near 5.4. On both hydroxyapatite and isoelectric focusing, delta GPA sometimes separated partially from the other two activities but not consistently. The gel filtration result shows that in conditioned medium of human origin, molecules having G-CSA are not the same as those having delta GPA, suggesting a dual factor requirement in the granulocytic lineage reminiscent of that in the erythroid pathway. The results suggesting that delta GPA might differ from E-BPA, on the other hand, were not consistent enough to establish their nonidentity. Single micromanipulated cells proved capable of forming erythroid or granulocytic colonies in the presence of either crude or partially purified activity. The results establish that human colony-forming cells are direct primary targets of growth factors in HLCM and HPCM.

Chromatography↗
PubMed1984

Sequential microdissection and scanning electron microscopy of ciliary microvascular castings.

Intracarotid injection of methylmethacrylate followed by tissue corrosion produces detailed replicas of the ocular microvasculature that can then be studied with the scanning electron microscope. The resultant photographs allow careful scrutiny of even the finest capillaries. However, when applied to the ciliary body, a complicated three dimensional system, we found stereo scanning electron micrography essential to fully appreciate its arteriolar and capillary interconnections. These stereoscopic analyses indicated that specific superficial vessels required excision to visualize deeper, previously hidden microvascular relationships. Using a pneumatically powered ultra microscissors guided by a micromanipulator we successfully removed these vessels. Deeper views were then obtained through repeat stereo scanning electron microscopy. This sequential microdissection and stereo scanning electron microscopy revealed that the major ciliary processes are supplied by two types of arterioles arising from the major arterial circle. Constricted anterior arterioles supply anterior and marginal aspects of the processes as well as interprocess capillary beds. Less constricted posterior arterioles feed capillaries confined to the base of the major processes as well as minor ciliary processes via posterior interprocess connections. Choroidal veins were seen to directly drain both anterior and posterior interprocess capillary beds.

Animals↗
PubMed1983

[Lasers in neurosurgery].

In recent years neurosurgeons have shown an increasing interest in lasers. An understanding of the basic laser mechanism and tissue effects is important. CO2 laser is an excellent no-touch tool for excising and evaporating brain tumors. It has several other uses in neurosurgery both with free hand technique and with microscope attachment and micromanipulator. Nd: YAG and Argon lasers are more effective for coagulation of blood vessels and dealing with vascular neoplasms. Advantages and disadvantages of this technique are discussed and compared with other methods like bipolar coagulation and CUSA. Indications for the use of the different laser types in neurosurgery are summarized and a prospect of laser in neurosurgery is given.

Brain Diseases↗
PubMedDate not supplied

Heterogeneity of lymphokine production by murine T-lymphocyte clones.

The production of lymphokines by alloreactive murine T-lymphocyte clones was investigated. Clones derived by limiting dilution or by micromanipulation were stimulated with T-cell-depleted irradiated allogeneic spleen cells, and the resulting supernatants were assayed for interleukin-2 (IL-2), interferon-gamma (gamma-IFN), macrophage-activating factor (MAF), B-cell helper factor (BHF) or granulocyte/macrophage colony-stimulating factor (GM-CSF). Lymphokine production was found to be heterogeneous at the clonal level, with both cytolytic and non-cytolytic clones being able to produce some (or all) of the factors tested. Comparison of a large number of independently derived clonal supernatants allowed the separation of IL-2, BHF and GM-CSF from each other and from MAF and gamma-IFN; however, no dissociation between the latter 2 lymphokines was observed.

Animals↗
PubMedDate not supplied

Collagen substrates for cytogenetic studies of domestic animal embryos.

A technique of cell culture on collagen substrate is proposed for cytogenetic studies on domestic animal embryos. The embryonic cells sampled by biopsy or micromanipulation grow on collagen coated cover slips in Leighton tubes with Ham's F12 medium, supplemented with 20 percent fetal calf serum. This method may be used to study the embryonic karyotype induced by a structural abnormality, as well as the karyotype of domestic animal embryos before transfer.

Animals↗
PubMed1982

Method for measurement of self-renewal capacity of clonogenic cells from biopsies of metastatic human malignant melanoma.

A procedure was developed to directly measure the self-renewal capacity of clonogenic cells from biopsies of metastatic human malignant melanoma. A culture of colony-forming cells was performed with bilayer agar in microtiter wells. The number of live tumor cells from biopsies of melanoma tissue was determined and was used to calculate plating efficiencies. Sequential photography showed that cells did not migrate in agar, thereby documenting that all the cells within colonies were direct descendants of clonogenic cells. A calibrated pneumatically controlled micropipet attached to a micromanipulator was used to quantitatively remove melanoma colonies without removing adjacent cells or agar. Plucked primary colonies were mechanically disaggregated into single cells; viability was greater than 95% as determined by trypan blue dye exclusion. Dose-related formation of secondary colonies was observed after replating of cells from pooled primary colonies. Cells from individual colonies were replated, and secondary colonies formed. These techniques allowed a simple and direct assessment of the self-renewal capacity of colony-forming melanoma cells.

Agar↗
PubMedDate not supplied

[DNA packing in the DNP fibrils of polytene chromosomes].

Isolated polytene chromosomes stained with acridine orange were stretched with micromanipulator needles. Changes of chromosome fluorescence polarization led to the conclusions: 1) almost complete orientation of DNP fibers is attained at very low levels of chromosome stretching (3--8 times) without irreversible disruption of chromomeres; 2) internucleosomal DNA in native DNP fibers is supercoiled and makes 30 degrees angle to the fiber axis.

Acridines↗
PubMed1981

Clonal nature of pluripotent hemopoietic precursors in vitro (CFU-mix).

Direct evidence is presented for the clonal nature of the mixed colonies from pluripotent hemopoietic precursors in vitro in adult murine marrow cells. Bone marrow cells from BDF1 mice were fractionated using the technique of velocity sedimentation according to Miller and Phillips to enrich the concentration of the mixed colony-forming units. After 3 h sedimentation, marrow cells in the 15th fraction were harvested and cultured using a methylcellulose culture assay. After 2 days of culture, dividing single cells were individually aspirated and transferred to fresh culture medium for mixed colonies using a Leitz micromanipulator. 92 macrophage-granulocyte colonies, 11 erythropoietic bursts, and 4 mixed colonies were detected in 358 single-cell culture experiments. The present results indicate that mixed colonies are clonal, and the mixed colony-forming units are pluripotent.

Animals↗
PubMedDate not supplied

[Serological study of Leishmania clones from experimentally and naturally infected sandflies].

A serological study of Leishmania clones from experimentally and naturally infected sand flies was undertaken. The cloning was done by means of Fonbrun's micromanipulator. Serological studies were conducted according to Adler's method in Safjanova's modification. Among the clones of Phlebotomus papatasi experimentally infected with Leishmania tropica major and L. gymnodactyli four were found to be serologically identical with L. tropica major, and two had close antigene relationships with both initial strains of Leishmania. No clones identical with L. gymnodactyli were found. By means of serological comparison to museum strains of Leishmania heterogeneity of the strains isolated from naturally infected sand flies and great variety of antigenic properties of clones obtained from them have been shown. Thus, among clones of Ph. caucasicus four are identical with L. donovani, one is closely related to Leptomonas pessoai and one displays no antigenic relationships to any standard strain of Leishmania. Two clones from naturally infected Ph. papatasi are identical with L. tropica major, one displays close antigenic relationships with L. tropica major and L. donovani and one could not be identified. The question is raised on the necessity to study possible mechanisms of genetic information exchange to explain the appearance of clones with mixed properties.

Animals↗