Use of lasers can cause visual impairment.
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Color Vision Defects↗
Biomedical subjects
K Hardy
Publications and source records attributed to K Hardy.
Glutamine improves human preimplantation development in vitro.
OBJECTIVE: To study the effect of glutamine on human preimplantation embryo development in vitro. DESIGN: A randomized, controlled, prospective study of 138 normally fertilized and nontransferred human embryos. On day 2 after fertilization, the embryos were allocated randomly to glucose-free medium with or without 1 mM of glutamine. SETTING: A university hospital-based IVF-ET program. PATIENT(S): Couples undergoing IVF treatment. INTERVENTION(S): Embryo culture. MAIN OUTCOME MEASURE(S): Blastocyst formation, trophectoderm and inner cell mass numbers, and pyruvate uptake and lactate production by individual embryos. RESULT(S): A higher proportion of embryos reached the morula (89% versus 68%, respectively) and blastocyst (71% versus 54%, respectively) stages when cultured with glutamine compared with embryos cultured without glutamine. Blastocyst cell numbers were not statistically significantly different for embryos grown in the presence or absence of glutamine. Pyruvate uptake and lactate production were higher in the presence of glutamine throughout development; these increases were statistically significant at the blastocyst stage. CONCLUSION(S): This study demonstrates that supplementation of the culture medium with glutamine is beneficial for human preimplantation embryo development in vitro, increasing the proportion of embryos that develop to the morula and blastocyst stages.
Blastocyst↗
Routine addition of human insulin-like growth factor-I ligand could benefit clinical in-vitro fertilization culture.
Animal studies suggest that the insulin-like growth factors play an important role in preimplantation embryo development. Human preimplantation embryos express mRNA for insulin-like growth factor-I receptor (IGF-IR) but the ligand, insulin-like growth factor-I (IGF-I), is not expressed by the embryo until after implantation. We tested the hypothesis that IGF-I produced by the female reproductive tract may bind to these receptors, augmenting embryo survival, growth and development. Transcripts of mRNA for IGF1 were detected using reverse transcription-polymerase chain reaction in midcycle human Fallopian tube. Immunohistochemistry localized immunoreactive IGF-I to the cytoplasm of all the major structures of the Fallopian tube, with the most intense staining seen in the tubal epithelial lining. Maternally produced IGF-I was present in the fluid found in the human tube and uterus at concentrations of 8.0 and 10.9 nM respectively. Supplementation of culture medium with IGF-I increased the proportion of embryos developing to the blastocyst stage from 35% in controls to 60% in the presence of IGF-I. In addition the total number of cells in day 6 blastocysts was increased by 19% (64.44 versus 54.08% in control, not significant), due entirely to a statistically significant 59% increase (25 versus 15.75%, P = 0.020) in the number of cells in the inner cell mass. The effect of IGF-I was mediated through the IGF-I receptor. Immunocytochemistry using an alphaIR3 antibody confirmed the presence of IGF-I receptor in human blastocysts and the same antibody completely inhibited the stimulation of blastocyst formation by IGF-I. These data suggest that human preimplantation development is enhanced by maternal IGF-I. Mimicking this in-vivo paracrine relationship may improve clinical in-vitro embryo culture and IVF pregnancy rates.
Blastocyst↗
Evaluation of the Biostar Chlamydia OIA assay with specimens from women attending a sexually transmitted disease clinic.
Chlamydia trachomatis infections are the most prevalent sexually transmitted diseases (STDs) in the United States. In acute-care settings such as clinics and emergency rooms, a desirable chlamydia screening assay should exhibit good sensitivity and good specificity and should provide test results while the patient is still present. The Biostar Chlamydia OIA (Biostar, Inc., Boulder, Colo.) is an optical immunoassay (OIA) that provides test results in less than 30 min and that uses a test format that allows office-based testing. This assay is performed entirely at room temperature without the need for rotators or other specialized equipment. The goal of this study was to compare the performance of the Biostar Chlamydia OIA for the detection of C. trachomatis with the performance of cell culture, direct fluorescent-antibody (DFA) assay (Syva MicroTrak; Syva Co., Palo Alto, Calif.), and PCR (Roche Amplicor Chlamydia trachomatis; Roche, Branchburg, N.J.) for the detection of C. trachomatis infections in women attending an urban STD clinic. For calculations of relative test performance (sensitivity, specificity, and positive and negative predictive values), patient specimens that yielded positive results by two or more of the four assays (cell culture, DFA assay, PCR, and OIA) were classified as "true infections." By these criteria, 42 of 306 total specimens were classified as positive for C. trachomatis (positive prevalence, 13.7%), 11 (3.6%; 10 by PCR and 1 by DFA assay) were positive by a single assay, and 253 (82.7%) were negative by all four tests. All culture-positive specimens were also positive by at least one other assay. Among the culture-negative specimens, 14(5%) specimens were positive by two of the three non-culture-based assays used. By using the criterion that positivity by at least two of the tests indicated a true infection,the relative sensitivities were as follows: culture and PCR, 92.9% each; Biostar Chlamydia OIA, 73.8%; and DFA assay, 59.5%.
Adolescent↗
Culture of human preimplantation embryos to the blastocyst stage: a comparison of 3 media.
Following culture for 2 days in Earle's balanced salt solution (EBSS), human embryos which remained after transfer were cultured in one of 3 media for 4 days, from the 2- to 4-cell stage to the blastocyst stage. Sibling embryos were divided equally between treatments. Throughout the 4 day culture period, embryos were assessed for morphology and development, as well as uptake and production of energy substrates. Cell numbers in the inner cell mass and trophectoderm were determined for embryos which reached the blastocyst stage. No significant effect was observed in the extent or rate of development to the 8-cell, morula or blastocyst stage between treatments. Uptake of pyruvate was related to concentration in the medium and no differences in glucose uptake were observed between media. Endogenous energy metabolism, as measured by lactate production, was significantly higher in Ham's F12 than in EBSS from day 3.5 onwards. Blastocyst cell numbers were also increased; 79.6+/-7.7 in Ham's F12 (n=17) and 57.8+/-5.2 in EBSS (n=19), p<0.05. Of the embryos which reached the blastocyst stage by day 5, 36% (14/25) had degenerated by day 6 in EBSS compared to only 19% (5/27) in Ham's F12 (p=0.06). Slightly higher rates of embryo survival between day 5 and 6 in Ham's F12 may account for the observed increase in blastocyst cell number. The results do not suggest that improved embryo development can be obtained using human tubal fluid or Ham's F12, in preference to EBSS during early cleavage stages, but the use of Ham's F12 may improve embryo survival at later stages of development.
Blastocyst↗
Structure of the calcium-binding echidna milk lysozyme at 1.9 A resolution.
A lysozyme isolated from the milk of a monotreme, the echidna, Tachyglossus aculeatus multiaculeatus, has been crystallized (space group P2(1), with unit-cell dimensions a = 37.1, b = 42.0, c = 38.1 A, beta = 91 degrees and Z = 2) and the structure refined to an R value of 0.167 for all measured data in the resolution range 7.0-1.9 A. It had previously been inferred from sequence homology with alpha-lactalbumins that echidna milk lysozyme (EML) would bind one calcium ion per molecule. This has been confirmed in the present study in which the largest peak in a difference Fourier synthesis is associated with a calcium ion. The calcium binding site of EML is very similar to that observed in baboon and human alpha-lactalbumins, and in a human lysozyme engineered to contain a calcium-binding site. The overall fold of the protein is similar to that of chick-type lysozymes. EML, like pigeon lysozyme, has only 125 residues terminating at a cysteine but in EML this forms a disulfide with a cysteine at residue 9 whereas the equivalent cysteine residue in all other lysozymes of known sequence occurs at position 6. These changes cause some minor structural rearrangements. The binding of calcium appears to have had little effect on the polypeptide backbone conformation and caused only small changes in the conformation of side chains coordinating the calcium ion. A homology modelling study [Acharya, Stuart, Phillips, McKenzie & Teahan (1994). J. Protein Chem. 13(6), 569-584] correctly predicted the overall structure of EML and the nature of its calcium binding site but generally failed to model some more subtle differences observed in the EML structure as evidenced by the fact that the homology model more closely resembles the starting structure from which the model was derived than it does the crystal structure.
Journal Article↗
Clinical trials need more ethnic balance.
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Clinical Trials as Topic↗
Expression of mRNA for the insulin-like growth factors and their receptors in human preimplantation embryos.
Insulin, insulin-like growth factor-I (Igf-I), and insulin-like growth factor-II (Igf-II) are known to enhance growth in mouse preimplantation embryos. The addition of insulin, Igf-I, and Igf-II to mouse embryos in culture results in an increase in protein synthesis, cell number, and the proportion of embryos developing to the blastocyst stage. To study the role of the insulin-like growth factors in early human development, the timing of gene expression of insulin, IGF1, IGF2, and their receptors was analysed. Reverse transcription polymerase chain reaction (RT-PCR) was used to examine the presence of transcripts in preimplantation embryos. Following reverse transcription, strategically designed nested primers were used for amplification from cDNA. Transcripts for all three receptors (insulin receptor, IGF1R, IGF2R) were present in human oocytes and preimplantation embryos. However, of the ligands, only IGF2 transcripts were detected. This is consistent with expressed patterns seen in the mouse. As in the human, mouse Igf2 is the only ligand in the family expressed and has been shown to have an autocrine effect on preimplantation development. It has previously been shown that insulin and Igf-I are produced by the mouse maternal reproductive tract and have a paracrine effect on the preimplantation embryo. We speculate that a similar relationship exists in the human and that preimplantation development may be regulated by IGFs from both embryonic (IGF-II) and maternal (insulin and IGF-I) sources.
Animals↗
Modelling the control of ovulation and polycystic ovary syndrome.
The control of ovulation in mammalian species appears to be a highly robust process. The primary mechanism is believed to be competition amongst a group of developing follicles, mediated by a hormonal feedback loop involving in the first instance the pituitary. Successful follicles reach maturity and ovulate, the remainder atrophy and die. A model of this control process has been derived by Lacker and his group. Based on simple qualitative assumptions about the hormonal feedback loop, this is able to reflect many of the basic physiological features of ovulation in mammals. However, a fundamental hypothesis of Lacker's work is that all follicles are identical and respond to hormonal signals in precisely the same way. Not only is this improbable, but it also leads to several aspects of the model which are qualitatively unrealistic, most notable of these is its inability to accurately model the condition known as Polycystic Ovary Syndrome. This common malfunction of the ovulatory control mechanism accounts for up to three-quarters of cases of anovulatory infertility in humans and its understanding is therefore of considerable medical significance. In this paper we extend the analysis of Lacker's model to the case of non-identical follicles; this allows us to obtain behaviour much closer to that observed in PCOS patients and to draw some tentative conclusions about the mechanisms underlying this condition.
Animals↗
Activation and signal transduction via mitogen-activated protein (MAP) kinases in T lymphocytes.
The various mitogen-activated protein (MAP) kinases have central roles in the signalling pathways of T lymphocytes. Their activation is uniquely dependent on dual phosphorylation of a serine/threonine and a tyrosine residue and is regulated by several levels of kinases in parallel cascades. In addition, both the MAP kinases and their upstream, activating kinases are regulated by several phosphatases. Although each of the MAP kinases have many cytoplasmic substrates, their ability to translocate to the nucleus means that they can transmit signals from the cytoplasm directly to transcription factors, which are sometimes nuclear bound. The MAP kinase cascades are activated in T lymphocytes by a variety of different external stimuli. They play an important role in transducing both the signal from T cell receptor and costimulatory molecules, on the T cell surface, and are able to regulate several of the transcription factors controlling the expression of critical genes, including that for IL-2. This review examines how the activation of several MAP kinases is regulated, their role in signal transduction initiated by a variety of stimuli, and how this may lead to different cellular responses.
Animals↗
IGF2 is parentally imprinted in human preimplantation embryos.
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Blastocyst↗
Cell death in the mammalian blastocyst.
Cell death is a widespread feature in the blastocysts of many mammals. Isolated cells in both the inner cell mass and the trophectoderm undergo cell death. These dying cells appear morphologically to be undergoing apoptosis. In mouse blastocysts, a wave of cell death is seen in vivo, suggesting that it plays an important role in normal development. However, cell death is increased under suboptimal culture conditions. There is evidence that levels of cell death are regulated by 'survival' factors produced both by the embryo itself and by the maternal reproductive tract. The role of cell death in development is unknown, but could involve the elimination of abnormal cells, or a sublineage of cells with an inappropriate developmental potential. Work in other systems has demonstrated that cell death is regulated by the activity of apoptosis genes. Whether these genes are implicated in blastocyst cell death, and the reasons for apoptosis in the early embryo, remain to be determined.
Animals↗
Effects of glutamine and taurine on preimplantation development and cleavage of mouse embryos in vitro.
Glutamine and taurine are reported to improve the development of mouse embryos in vitro, and glutamine is a component in CZB and KSOM, media optimized to overcome the 2-cell block in outbred strains of mice. Here we have studied the development of embryos from F1 hybrid female mice in CZB and KSOM, from the zygote to the blastocyst stage, in the presence and absence of 1 mM glutamine and/or 5 mM taurine. Blastocyst formation, rate of development, number of trophectoderm and inner cell mass cells, mitosis, and cell death were examined. Glutamine had no effect on the proportion of embryos developing to the blastocyst stage, but it significantly reduced cell number at the blastocyst stage. The trophectoderm was the lineage most affected, showing increased levels of cell death. Changing the media after 48 h, to remove any possible buildup of toxic metabolites, did not reverse the inhibition by glutamine. Taurine had no effect on blastocyst development of cell number. Development in glutamine-free KSOM (KSOM-Gln) was compared to that in standard CZB and KSOM with glutamine and M16. Early cleavage was slower in M16, but by Day 5 over 84% of embryos had developed to the blastocyst stage in all media, with a similar cell number in M16, CZB, and KSOM. Cell numbers in blastocysts cultured in KSOM-Gln were significantly higher than in the other media and approached those found in vivo.
Animals↗
Inhibition of human neutrophil beta2-integrin-dependent adherence by hyperbaric O2.
Animal and clinical investigations have reported that exposure to hyperbaric O(2) improved the outcome of some reperfusion injuries. Animal studies have suggested that this may be due to an inhibition of leukocyte adherence to injured endothelium. This investigation tested the hypothesis that exposure to hyperbaric O(2) would inhibit beta2-integrin-dependent adherence of human neutrophils. Subjects were exposed to O(2) at partial pressures of up to 3 atmospheres absolute (ATA; 1 ATA = 0.1 MPa) for 45 min, and neutrophil binding to nylon columns and to fibrinogen-coated surfaces was measured. Exposure to O(2) at 2.8 or 3.0 ATA inhibited beta2-integrin-dependent neutrophil adherence but had no effect on the cell-surface expression of beta2-integrins, respiratory burst in response to phorbol ester, or non-beta2-integrin-dependent adherence to plastic plates coated with a fibronectin-like protein. beta2-Integrin adherence was restored by incubating blood with 8-bromoguanosine 3',5'-cyclic monophosphate (cGMP) and hyperbaric O(2) inhibited synthesis of cGMP by neutrophils stimulated with N-formyl-Met-Leu-Phe (FMLP). In studies of cell fractions, the activity of membrane guanylate cyclase was found to be increased by incubation with FMLP as well as by atrial natriuretic peptide (ANP) plus ATP. Hyperbaric O(2) had no effect on the basal activity of soluble or membrane-bound guanylate cyclase. However, hyperbaric O(2) inhibited the function of both the extracellular binding domain of membrane guanylate cyclase as well as intracellular catalytic activity. There are approximately 7,300 membrane guanylate cyclase molecules per cell, based on binding studies with ANP, with a dissociation constant of approximately 450 pM. Hyperbaric O(2) inhibits the function of human neutrophil beta2-integrins by a process linked to impaired synthesis of cGMP.
Adult↗
Follow-up of radial arterial catheterization for positron emission tomography studies.
Radial arterial catheterization is needed for repeated arterial blood samples to construct tracer input curves of positron emission tomography (PET) scans (Herscovitch [1993]: Rheum Dis Clin North Am 19:765-794). Complications resulting from such short-term catheterizations are rare. Sixteen investigators followed 106 subjects who had arterial lines placed in the context of a PET study. Abnormalities were reported in 8 of 106 (7.5%) cases. Of these eight cases, three (37.5%) were inpatients diagnosed with anorexia nervosa, a condition that may represent a risk factor. All abnormalities were benign, did not affect motor function, and did not require medical intervention.
Adult↗
Recombinant human growth hormone, insulin-like growth factor 1, and combination therapy in AIDS-associated wasting. A randomized, double-blind, placebo-controlled trial.
OBJECTIVE: To increase lean body mass and improve health status in patients with wasting associated with the acquired immunodeficiency syndrome (AIDS) by treatment with recombinant human growth hormone (rhGH), recombinant human insulin-like growth factor 1 (rhIGF-1), or both. DESIGN: Randomized, double-blind, placebo-controlled clinical trial. SETTING: University of New Mexico Clinical Research Center and University of Texas Southwestern Medical Center. PATIENTS: 60 patients with AIDS and wasting as defined by the Centers for Disease Control and Prevention. Patients were divided into four groups of 15 patients each. INTERVENTION: Group 1 received 1.4 mg of rhGH once daily plus placebo twice daily; group 2 received 5 mg of rhIGF-1 twice daily plus placebo once daily; group 3 received 5 mg of rhIGF-1 twice daily plus 1.4 mg of rhGH once daily; and group 4 received placebo three times daily. MEASUREMENTS: Body weight, body composition, muscle strength, protein catabolism, quality of life, and immune status were assessed at baseline, and changes in these variables were measured at 6 and 12 weeks. RESULTS: At 6 weeks, lean body mass had increased and total fat mass had decreased in the groups receiving rhGH, rhIGF-1, or both. Group 3 had the greatest changes in lean body mass (mean +/- SE, 3.2 +/- 0.59 kg; P < 0.001); only in this group were changes in body mass maintained at 12 weeks. Only patients in group 1 had improvement in muscular strength of the knees and upper body (P = 0.04) and quality of life (P = 0.01). Immunologic function did not improve in any group. CONCLUSIONS: Growth factor therapy had significantly increased lean body mass and decreased fat mass by 6 weeks, but these improvements persisted for 12 weeks only in group 3. Growth factor therapy at the dosages used in this study is not recommended because the magnitude of weight gain was modest and improvements in quality-of-life measures varied.
Adult↗
Presentations of pituitary insufficiency and Addison's disease in insulin dependent diabetes may be similar.
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Addison Disease↗
Presynaptic dopaminergic deficits in Lesch-Nyhan disease.
BACKGROUND: Lesch-Nyhan disease is a rare, devastating, X-linked recessive disorder of purine synthesis. Patients present with hyperuricemia, choreoathetosis, dystonia, and aggressive and self-injurious behavior. Although the genetic and biochemical abnormalities have been identified, the causes of the neuropsychiatric syndrome remain unclear. METHODS: We used positron-emission tomography to measure presynaptic accumulation of fluorodopa F 18 tracer in the dopaminergic regions of the brains of 12 patients with Lesch-Nyhan disease (age, 10 to 20 years) and 15 healthy controls (age, 12 to 23). The results were expressed as ratios of specific to nonspecific radioactive counts. A low ratio indicates decreased dopa decarboxylase activity and dopamine storage. RESULTS: The fluorodopa F 18 ratio was significantly lower in the putamen (31 percent of control values), caudate nucleus (39 percent), frontal cortex (44 percent), and ventral tegmental complex (substantia nigra and ventral tegmentum; 57 percent) in the patients with Lesch-Nyhan disease than in the controls. Uptake of the tracer was abnormally low even in the youngest patients tested, and there was no overlap in the values between patients and controls. CONCLUSIONS: Patients with Lesch-Nyhan disease have abnormally few dopaminergic nerve terminals and cell bodies. The abnormality involves all dopaminergic pathways and is not restricted to the basal ganglia. These dopaminergic deficits are pervasive and appear to be developmental in origin, which suggests that they contribute to the characteristic neuropsychiatric manifestations of the disease.
Adolescent↗