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Biomedical subjects

K Elder

Publications and source records attributed to K Elder.

18 recordsLinked to original sources
PubMed2005

Implantation failures: success of assisted hatching with quarter-laser zona thinning.

Implantation failure after IVF is one of the factors associated with a reduced chance of pregnancy for some patients. Assisted hatching methodologies are designed to facilitate the embryo's escape from the zona pellucida, and this strategy has been suggested as a means of improving pregnancy rates in patients with previous implantation failure. The aim of this prospective and randomized study was to evaluate the efficacy of quarter-laser zona thinning assisted hatching (qLZT-AH) in improving the implantation of embryos in patients with previous implantation failure. A total of 150 patients with a history of previous implantation failure were treated with intracytoplasmic sperm injection, and allocated into two groups: group 1, only one previous implantation failure, and group 2, repeated implantation failures. The patients in each group were randomized at the time of embryo transfer into a control group (no qLZT-AH) or experimental group where qLZT-AH was performed. For patients with repeated implantation failures, the implantation rate in those who received laser-thinned embryos was significantly higher (P = 0.02) than in those whose embryos were not laser-thinned (10.9 and 2.6% respectively). However, this difference was not observed in patients who presented with only one previous implantation failure. The data demonstrate that qLZT-AH is an effective strategy for improving the implantation of embryos in patients with repeated implantation failures.

Adult↗
PubMed2001

Quantification of the graphical details of collagen fibrils in transmission electron micrographs.

A novel 2D image analysis technique is demonstrated. Using the digitized images of articular cartilage from transmission electron microscopy (TEM), this technique performs a localized 'vector' analysis at each region that is large enough to include several or tens of collagen fibrils but small enough to provide a fine resolution for the whole tissue. For each small and localized region, the morphology of the collagen fibrils can be characterized by three quantities essential to the nature of the tissue: the concentration of the fibrils, the overall orientation of the fibrils, and the anisotropy of the fibrils. This technique is capable of providing new insight to the existing technology by assigning quantitative attributes to the qualitative graphics. The assigned quantities are sensitive to the fine structure of the collagen matrix and meaningful in the architectural nature of the collagen matrix. These quantities could provide a critical linkage between the ultrastructure of the tissue and the macroscopic behaviours of the material. In addition, coarse-graining the microscopic resolution of EM without compromising the essential features of the tissue's structure provides a direct view of the tissue's morphology and permits direct correlations and comparisons among interdisciplinary techniques.

Animals↗
PubMed2001

A physiological replacement for polyvinylpyrrolidone (PVP) in assisted reproductive technology.

The technique of intracytoplasmic sperm injection (ICSI) requires mechanical immobilization of the sperm that are to be injected; damage thus caused to the sperm membrane is considered to be necessary to activate the sperm for fertilization. Mechanical immobilization and the injection procedure are facilitated by introducing the sperm into a viscous medium that will hinder motility: a solution of polyvinylpyrrolidone (PVP) has been used successfully for this purpose. PVP is an artificial polymer, which has been regarded as chemically inert, although adverse effects have been reported as a result of its use both in vivo and in vitro. Therefore, the use of hyaluronate, the natural component of the extracellular matrix of the cumulus-oocyte complex, was investigated as a replacement for PVP during ICSI. A solution of hyaluronate was found to be as effective as PVP in facilitating the injection procedure, its effect on sperm motility was readily reversible, and its use did not affect the outcome of the treatment cycles in terms of fertilization, pregnancy and live birth rates. Every attempt should be made to eliminate artificial factors in assisted reproductive procedures. Hyaluronate, a natural and readily degradable glycosaminoglycan can be used as a substitute for the artificial PVP polymer without jeopardising the outcome of the treatment cycle.

Adult↗
PubMed2000

The scaphotrapezio-trapezoidal joint. Part 2: A kinematic study.

Kinematics of the scaphotrapezio-trapezoidal joint during wrist flexion/extension motion (FEM) and radial/ulnar deviation (RUD) was investigated using a 3-dimensional dynamic motion analysis system. The scaphoid/trapezoid motion was found to be a rotational motion obliquely oriented relative to the sagittal plane of the wrist and described in an ulnoflexion/radial extension motion plane in both FEM and RUD of the wrist. The axis of rotation of the scaphoid/trapezoid motion during both FEM and RUD wrist motions was essentially the same and runs through the radiopalmar aspect of the distal scaphoid and the waist of the capitate. Motion analysis also revealed that the trapezium-trapezoid and trapezoid-capitate joints are essentially immobile. Hence, the scaphotrapezio-trapezoidal motion is considered to be a single degree of freedom that is essentially the same in both FEM and RUD of the wrist.

Adult↗
PubMed1995

Quantification of anatomic, geometric, and load transfer characteristics of the wrist joint.

The work reported here is an assimilation of 8 years of research, the purpose of which was to gain a better understanding of the normal and abnormal workings of the wrist joint. The results are summarized in three major areas of concentration: descriptive anatomic studies, which include direct measurements of cadaver specimens, biomechanical loading studies to define load distribution through normal and abnormal wrists, and three-dimensional (3D) anatomy studies using solid models derived from computed tomographic (CT) images of in vivo and cadaver wrists. The descriptive anatomic studies used 393 cadaver wrists to evaluate the incidence and distribution of anatomic features, arthroses, chondromalacia, and soft-tissue lesions. The data were analyzed for any statistically significant associations among different variables. The biomechanical studies characterized the biomechanics of the human wrist in a variety of normal, simulated traumatic, and surgically treated conditions. The results of the load studies have provided clinically relevant information on the normal anatomy and functional mechanics of the wrist as well as guidelines for the treatment of a number of different fractures and ligament injuries. The 3D anatomic studies use quantitative analysis of 3D reconstructions of CT scan data to build a normative database of carpal bone morphology. Thirty-five wrists were imaged in a CT scanner. Quantitative measurements of volume, surface area, maximum length, and intercarpal distances were than assessed. A reliable 3D carpal height ratio (3DCHR) was calculated by dividing the capitate maximum length by the carpal height, which is the minimum distance between the fourth metacarpal and the radius.

Adolescent↗
PubMed1993

Measurement of carpal bone geometry by computer analysis of three-dimensional CT images.

The aim of this project was noninvasively to analyze and quantitate the geometry, load transfer characteristics, and spatial relationships of the carpal bones by using a new three-dimensional CT scan reconstruction technique. The determination of mechanical parameters such as distances between centroids and between bone surfaces, carpal alignment, volumes, surface areas, and contact areas can provide the basis for comparison between normal wrists and wrists with a variety of progressive instability patterns, types of fracture, pathologic and posttraumatic states, and different simulated surgical procedures. This new technology has demonstrated a volumetric accuracy of 94% and a linear accuracy of 97%. Simultaneous analysis of all articulating surfaces of multiple joints can be performed in cadavers and in patients because of the noninvasive nature of the imaging reconstruction technique. This new research offers much more information than has previously been available. It also promises direct application to the clinical setting and eliminates several limitations and questions that were inescapable with previous technology.

Adult↗
PubMed1991

Intercellular communication in the early human embryo.

A preliminary study on intercellular communicative devices in the early human embryo has been made using dye-coupling techniques and electron microscopy (EM). Lucifer yellow injected into single blastomeres of embryos at the 4-cell stage up to the late morula stage did not spread to neighbouring cells, indicating that gap junctions and cytoplasmic bridges are not significant pathways for information transfer. Dye spread was first observed in the blastocyst stage, where trophectoderm cells and inner mass cells were shown to be in communication through gap junctions. Studies at the EM level confirmed this finding. Tight junctions and desmosome-like structures, apparent from the 6-cell stage onward, were located both peripherally and centrally and were initially nonzonular. The role of intercellular devices in the primary differentiation of the human embryo is discussed.

Blastocyst↗
PubMed1991

The influence of in-vitro development upon post-thaw survival and implantation of cryopreserved human blastocysts.

Blastocysts from 198 patients were frozen using glycerol as cryoprotectant. No difference in the post-thaw survival of blastocysts or implantation rates was found between 177 patients (122 transfers) with all surplus embryos cultured to blastocysts before freezing and 20 patients (12 transfers) whose embryos were considered unsuitable for freezing during cleavage and were then frozen as blastocysts. Nineteen pregnancies were achieved, of which six aborted. Pre-freezing morphology was similar in blastocysts of patients in groups 1 and 2 and did not relate to their survival after cryopreservation. A significantly lower proportion with suspected damage after thawing was present among patients becoming pregnant after transfers of single blastocysts (P less than 0.01) and implanting embryos were in general more expanded at the time of transfer. No differences were detected between blastocysts resulting in normal development and those leading to abortion. The developmental consequences of damage to human blastocysts are discussed.

Adult↗
PubMed1990

In vitro fertilization and development of one of two human oocytes with fused zonae pellucidae: case report.

This report describes a pair of human oocytes of differing maturities but fused at the zona pellucida, believed to have originated from a binovular follicle. After insemination in vitro, one oocyte fertilized and developed into an expanded blastocyst, whereas the other, which contained a germinal vesicle, degenerated. A biopsy was aspirated from the blastocyst, which subsequently re-expanded but did not hatch.

Adult↗
PubMed1990

Effect of cell number at freezing upon survival and viability of cleaving embryos generated from stimulated IVF cycles.

The survival of cleaving embryos after freezing and thawing has been assessed. First, comparisons were made of the proportions of embryos in which all blastomeres were viable cells after thawing, following various forms of ovarian stimulation. A flare-up protocol using a GnRH-agonist (buserelin) produced significantly higher numbers of these embryos than a pituitary down-regulation protocol (P less than 0.05), though neither was significantly different from clomiphene citrate/HMG stimulation. Secondly, other parameters of embryo survival e.g. proportions with one or more surviving cells and pregnancy rates were assessed and were similar among stimulation protocols and treatments in the embryo replacement cycle. Survival of blastomeres in 2- to 8-cell embryos was inversely related to the theoretical total surface area of all blastomeres in the embryo. Thawed embryos with one or more blastomeres damaged during freezing had the same capacity to produce pregnancies as did those with all blastomeres intact. The survival of individual cells was clearly related to the stage at which the cleaving embryo is frozen, but moderate loss of cells does not significantly influence implantation.

Blastomeres↗
PubMed1990

Rare ectopic pregnancies after in-vitro fertilization: one unilateral twin and four bilateral tubal pregnancies.

Between 1985 and 1989, one unilateral twin and four bilateral tubal pregnancies were encountered among 124 extrauterine pregnancies and 1648 intrauterine pregnancies following in-vitro fertilization and embryo transfer. The two factors associated with this high incidence of single and multiple extrauterine pregnancies were tubal damage and multiple embryo transfer. Embryos at different stages of development appear to have the capacity to implant ectopically. Despite advances in diagnostic capabilities, ectopic pregnancy remains a major cause of maternal mortality. Early diagnosis prior to rupture must be made if mortality and morbidity are to be abolished. The use of transvaginal sonography has improved the diagnosis of ectopic pregnancy and should be routinely used in all pregnancies following assisted conception. The identification of an intrauterine pregnancy should not be sufficient to rule out the possibility of an extrauterine pregnancy or even bilateral tubal pregnancies.

Adult↗
PubMed1984

Cancer mortality in relatives of retinoblastoma patients.

The risk of other cancers in relatives of retinoblastoma (RTB) patients was determined by a survey of the mortality experience of siblings, parents, parental siblings, and grandparents of all U.S. or Canadian RTB patients referred to The University of Texas M.D. Anderson Hospital and Tumor Institute between 1944 and 1980. Expected mortality was ascertained by the application of age-, sex-, race-, and calendar year-specific U.S. mortality rates to the observed person-years. Among 607 relatives of 33 unilateral-sporadic RTB probands, no excess in cancer deaths was observed (observed/expected = 18/22). Among 733 relatives of 47 bilateral-familial RTB probands, a slight excess in cancer deaths was observed (41/31). A significant excess in cancer deaths was occurred in relatives under age 55 years (18/9) and in fathers (7/1) of the bilateral RTB probands. To determine whether the cancer excess was related to some unique allele associated with second tumors in RTB survivors, the cancer mortality of 203 relatives of the 14 RTB patients with second tumors was examined, and no excess was observed (11/11). To determine whether the excess might be attributable to an unexpressed RTB gene or precursor, the mortality experience was examined in 6 kindreds in which parents, unaffected by RTB, had more than 1 child with RTB. Among these 72 relatives a significant excess in cancer deaths was observed (8/2). The findings demonstrate a modest overall cancer excess in relatives of hereditary RTB patients and suggest it may be attributable to an unexpressed RTB gene or precursor in a small number of kindreds. Mechanisms for an apparent "precursor" might involve a delayed mutation, genetic mosaicism, or a submicroscopic balanced chromosomal translocation.

Adolescent↗
PubMed1980

Studies on the structure of the haemagglutinin.

The biosynthesis of the haemagglutinin glycoproteins of infectious influenza virus particles involves proteolytic cleavage of the primary translation products and the amino acid sequences at the two sites of processing are presented. In addition, details of the primary structure of the haemagglutinin of A/Japan/305/57 (H2N1) are reported and compared with information available for haemagglutinins of other subtypes.

Amino Acid Sequence↗
PubMed1980

Adjuvant chemotherapy in nonmetastatic osteosarcoma: a Southwest Oncology Group Study.

This report updates experience with the CONPADRI-I, COMPADRI-II, and COMPADRI-III adjuvant chemotherapy programs for the treatment of nonmetastatic osteosarcoma. A total of 200 patients received one of the three regimens. The analysis of response to treatment is based on disease-free survival time (DFS time). The effect of treatment, age, sex, site of disease involvement, and race on DFS time were investigated. Cox's life-table regression analysis found only sex to have a significant effect on DFS time with males having 1.8 times the risk of recurrence or death per unit time as female patients (P = 0.004). An analysis of the 81 patients still alive and disease-free 18 months after the start of treatment shows significantly longer DFS time for CONPADRI-I than COMPADRI-II patients (P = 0.01). This trend is true for both male (P = 0.12) and female (P = 0.08) patients.

Adolescent↗