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Biomedical subjects

D Kiefer

Publications and source records attributed to D Kiefer.

At least 19 recordsLinked to original sources
PubMed2004

Effect of antagonists vs agonists on in vitro fertilization outcome.

PURPOSE: To compare outcome following in vitro fertilization-embryo transfer (IVF-ET) using controlled ovarian hyperstimulation (COH) regimens using either the gonadotropin-releasing hormone (GnRH) agonist leuprolide acetate vs the GnRH antagonist ganirelix. METHODS: Women needing IVF for conception were randomly assigned to 300 IU of gonadotropins with ganirelix used in the follicular phase when a follicle with a 14 mm average diameter was attained vs a regimen using leuprolide acetate from the mid-luteal phase of the previous cycle. RESULTS: There were no differences found in clinical, ongoing, delivered pregnancy rates or implantation rates between groups. CONCLUSIONS: The use of GnRH antagonists do not seem to reduce IVF outcome compared to using GnRH agonists in COH regimens.

Adult↗
PubMed2002

Grey zone score for hypo-osmotic swelling test (HOST) is not associated with embryo implantation defects.

PURPOSE: To evaluate the clinical significance of the grey zone range (50-59%) of the hypo-osmotic swelling test (HOST) on sperm samples. METHODS: Clinical and viable pregnancy rates and implantantion rates following in vitro fertilization-embryo transfer (IVF-ET) were determined in couples where the male partner scored between 50-59% on the HOST. The data were further evaluated according to the discrepancy between viability and HOST. Finally, the study assigned whether treating sperm with the protein digestive enzyme chymotrypsin had any effect on pregnancy outcome. RESULTS: Pregnancy and implantation rates were comparable for couples with grey zone HOST scores with the normal IVF rate for the center. Having a large discrepancy between viability and HOST scores had no clinical significance nor did treatment with chymotrypsin. CONCLUSION: In contrast to HOST scores < 50% where extremely poor implantation rates are noted, grey zone scores have no clinical significance.

Adult↗
PubMed2002

A study to determine if embryo cryopreservation influences the potential of rapidly growing embryos to successfully implant in uterine environments not influenced by controlled ovarian hyperstimulation.

PURPOSE: To determine if transferring at least one embryo with eight blastomeres at 72 hours improves prognosis of donor oocyte recipients. The study aim was to verify if cryopreservation increases or decreases the advantage of rapidly growing embryos. The study could exclude the influence of controlled ovarian hyperstimulation (COH) on the uterine environment. METHODS: All transfers, fresh or frozen, using exclusively embryos that resulted from fertilization of donor oocytes over a three-year period were evaluated. RESULTS: Significantly higher pregnancy rates (PRs) and delivery rates were found in donor oocyte recipients receiving at least one eight-cell embryo compared to transfers without any eight-cell embryos. These differences were not found when comparing frozen embryo transfers (ETs). The data could not be explained by confounding variables. CONCLUSIONS: The inclusion of at least one 8-cell embryo on day 3 fresh ET resulted in higher PRs even without the influence of COH. However, higher blastomere number did not influence frozen ET outcome.

Blastomeres↗
PubMed2002

Evidence that exclusive use of Follistim may produce better pregnancy results than the use of Gonal-F following in vitro fertilization (IVF) - embryo transfer (ET).

PURPOSE: To evaluate whether the equal mixture of human menopausal gonadotropin (hMG) to recombinant (r) follicle stimulating hormone (FSH) for controlled ovarian hyperstimulation (COH) adversely affects outcome following in vitro fertilization (IVF). Furthermore, to determine if the specific rFSH preparation used has any differing effects on outcome. METHODS: Retrospective study of women using the luteal phase leuprolide acetate-gonadotropin COH regimen. Outcome measures included clinical and viable pregnancy rates (PRs) and implantation rates. RESULTS: The clinical and viable PRs and implantation rates were significantly lower in the group receiving exclusively Gonal-F. Addition of hMG to the treatment protocol not only did not lower the PRs further, but in fact seemed to obviate the adverse effect of Gonal-F. CONCLUSION: Since exclusive use of Gonal-F did not adversely affect fertilization rates or quality of embryos we suspect its exclusive use in some way makes the uterine environment less receptive.

Adult↗
PubMed2002

The importance of number of blastomeres when embryos are transferred in the absence of controlled ovarian hyperstimulation.

PURPOSE: To determine if the previous findings that transferring embryos with a higher number of blastomeres results in higher pregnancy rates following fresh but not frozen embryo transfer (ET) was related to the use of controlled ovarian hyperstimulation (COH) in the former but not in the latter. METHODS: Retrospective review of pregnancy and implantation rates following fresh embryo transfer of donor egg recipient cycles (where no COH is used) vs frozen ETs during the same time period according to whether there was at least one embryo with eight blastomeres transferred or not. RESULTS: Significantly higher pregnancy rates with an 8-cell ET in donor oocyte recipient cycles but not frozen ETs. CONCLUSIONS: A less favorable uterine environment caused by the use of high dose gonadotropin is not responsible for the once again observed difference in higher pregnancy rates with higher blastomere number in fresh vs frozen ET. However, an effect of the gonadotropin releasing hormone analogue was not ruled out by this study.

Blastomeres↗
PubMed2001

Indecisive M13 procoat protein mutants bind to SecA but do not activate the translocation ATPase.

The M13 procoat protein serves as the paradigm for the Sec-independent membrane insertion pathway. This protein is inserted into the inner membrane of Escherichia coli with two hydrophobic regions and a central periplasmic loop region of 20 amino acid residues. Extension of the periplasmic loop region renders M13 procoat membrane insertion Sec-dependent. Loop regions with 118 or more residues required SecA and SecYEG and were efficiently translocated in vivo. Two mutants having loop regions of 80 and 100 residues, respectively, interacted with SecA but failed to activate the membrane translocation ATPase of SecA in vitro. Similarly, a procoat mutant with two additional glutamyl residues in the loop region showed binding to SecA but did not stimulate the ATPase. The three mutants were also defective for precursor-stimulated binding of SecA to the membrane surface. Remarkably, the mutant proteins act as competitive inhibitors of the Sec translocase. This suggests that the region to be translocated is sensed by SecA but the activation of the SecA translocation ATPase is only successful for substrates with a minimum length of the translocated region.

Adenosine Triphosphatases↗
PubMed2001

Ovarian cancer in a woman previously diagnosed with endometriosis and an extremely high serum CA-125 level.

PURPOSE: Follow-up of a woman with a serum CA-125 level > 1000 U/mL where laparoscopy only found endometriosis. METHODS: Case report-- re-evaluation several years later. RESULTS: Extensive clear-cell carcinoma of ovary with metastases leading to death. CONCLUSION: This case suggests that bilateral oophorectomy should be performed in women not desiring any more children if the serum CA- 125 level is very high even if only endometriosis is found initially.

Adenocarcinoma, Clear Cell↗
PubMed1999

Hydrophobic forces drive spontaneous membrane insertion of the bacteriophage Pf3 coat protein without topological control.

Bacterial integral inner membrane proteins are either translocated across the lipid bilayer using an energy-driven enzyme, such as the Sec translocase, or they might interact directly with the membrane due to hydrophobic forces. We report that the single-spanning Pf3 coat protein is spontaneously inserted into the membrane of Escherichia coli and requires the electrical component of the membrane potential (DeltaPsi) to translocate its N-terminal region. This results in a final N(out)C(in) orientation of the protein in the cytoplasmic membrane, due the potential-driven translocation of the aspartyl residue at position 18 in the hydrophilic N-terminal tail. Uncharged protein tails are only translocated when the hydrophobic transmembrane region of the protein has been extended. An extended transmembrane anchor allows membrane insertion in the absence of an electrochemical membrane potential, but also causes the loss of a strict determination of the topology.

Adenosine Triphosphatases↗
PubMed1999

Assessing the risks and benefits of herbal medicine: an overview of scientific evidence.

The use of herbal medicine is widespread and growing, with as many as 3 in 10 Americans using botanical remedies in a given year. Because many herbal medicines have significant pharmacological activity, and thus potential adverse effects and drug interactions, healthcare professionals must be familiar with this therapeutic modality. This article summarizes the history and current use of plant-based medicine and highlights the evidence of the risks and benefits associated with 6 plants: echinacea, garlic, ginger, ginkgo, St John's wort, and valerian. Therapies outside the medical mainstream tend to suffer from a dearth of research and critical evaluation. Critics and supporters alike note the conceptual and practical difficulties in studying many complementary and alternative therapies such as acupuncture, homeopathy, and meditation. Herbal medicine, however, lends itself well to standard evaluation methods. This article summarizes and evaluates evidence from randomized controlled trials and meta-analyses. We present the results of meta-analyses and subsequent randomized controlled trials for garlic and St John's wort; a comprehensive critical review and subsequent randomized controlled trials for ginkgo; and summaries of all identified randomized controlled trials for echinacea, ginger, and valerian.

Ericales↗
PubMed1997

Negatively charged amino acid residues play an active role in orienting the Sec-independent Pf3 coat protein in the Escherichia coli inner membrane.

The coat protein of Pseudomonas aeruginosa phage Pf3 is transiently inserted into the bacterial inner membrane with a single transmembrane anchor sequence in the N(out)C(in) orientation. The N-terminal sequence immediately flanking the membrane anchor contains one negatively charged residue, whereas the C-terminal hydrophilic segment has two positively charged residues. To investigate how the orientation of this protein is achieved, the three flanking charged amino acid residues were altered. Membrane insertion was analyzed in vivo using the accessibility to externally added protease and in vitro by testing the insertion into inverted Escherichia coli membrane vesicles. In both systems, the orientation of the protein was completely reversed for the oppositely charged mutant coat protein (RD mutant). In addition, we show in vivo that the electrochemical membrane potential is necessary for the translocation of both the wild-type and the mutant Pf3 coat proteins, suggesting that membrane insertion is driven by electrophoretic forces.

Amino Acid Sequence↗
PubMed1997

Evidence that oligoasthenozoospermia may be an etiologic factor for spontaneous abortion after in vitro fertilization-embryo transfer.

OBJECTIVE: To evaluate whether oligoasthenozoospermia may lead to a higher spontaneous abortion (SAB) rate once a pregnancy is established by IVF-ET. DESIGN: Retrospective clinical observational study. SETTING: University-based IVF program. PATIENT(S): Three hundred sixty-four couples with normal semen parameters who underwent IVF-ET with conventional sperm incubation; 70 couples with oligoasthenozoospermia but without marked abnormal sperm morphology (< 4% normal forms using strict criteria) who underwent ET after IVF with conventional sperm incubation; and 20 couples with oligoasthenozoospermia but without abnormal sperm morphology who underwent ET after IVF with intracytoplasmic sperm injection (ICSI). MAIN OUTCOME MEASURE(S): Implantation rate, clinical pregnancy rate, SAB rate, and delivery rate after IVF-ET. RESULT(S): Despite similar pregnancy and implantation rates per ET, as a result of a higher SAB rate (40.0% versus 11.7%), the delivery rates were lower in the female partners of men with oligoasthenozoospermia. Similar patients who used ICSI had a 0% SAB rate. CONCLUSION(S): Oligoasthenozoospermia should be considered a possible risk factor for SAB in IVF achieved pregnancies. Further studies are needed to determine whether ICSI reduces the risk of SAB associated with oligoasthenozoospermia.

Abortion, Spontaneous↗
PubMed1994

Evidence for a loop-like insertion mechanism of pro-Omp A into the inner membrane of Escherichia coli.

We have studied the insertion of pro-OmpA into the Escherichia coli membrane in vivo using various mutants that have either alterations in the amino-terminal parts of the signal peptide or in the mature region that flanks the signal peptide. A pro-OmpA mutant with an amino terminal extension of 142 residues derived from ribulokinase (AraB) was analysed for its membrane insertion. The AraB portion, which includes a cluster of seven charged residues close to the signal sequence, did not interfere with the Sec components and allowed efficient export of OmpA. During translocation the AraB portion remained in the cytoplasm. Further mutants of OmpA were constructed in the carboxy-terminal region flanking the signal sequence. Pro-OmpA does not translocate across the membrane when a charge cluster, comprised of Lys-Arg-Arg-Glu-Arg, is introduced after positions 5, 11 or 15 of the mature region, but is translocated when the cluster is introduced after position 22. This defines a region of about 20 residues in the mature part of pro-OmpA that is crucial for membrane insertion. These results suggest that in the case of the Sec-dependent pro-OmpA, as with the Sec-independent M13 procoat, the precursor assumes a loop-like structure involving the signal peptide and the early part of the mature region, leaving the amino terminus of the signal peptide at the cytoplasmic face.

Amino Acid Sequence↗
PubMed1993

Effects of Percoll discontinuous density gradients vs SpermPrep II vs Sephadex G-50 gel filtration on semen parameters.

There are various methods of separating sperm from seminal plasma for subsequent intrauterine insemination (IUI) and for in vitro fertilization (IVF). The purpose of the present study was to assess and compare semen parameters following Sephadex, Percoll and SpermPrep II separation techniques. The SpermPrep II is also a Sephadex preparation but uses a different bead size, less Sephadex and is a quicker method. The specimens (n = 16) were initially evaluated for count, (C; x 10(6)/ml)% motility (MO), grade of motility (GR; %), and HOS test scores. Each specimen was then divided into 3 equal aliquots and prepared as follows: 1) layered onto a modified Percoll discontinuous density gradient column; 2) processed using SpermPrep II; and 3) filtered through a Sephadex gel filtration column (G-50). The results show all 3 treatments yielded lower (p < 0.01) counts as compared to control values but no differences were noted among them. Percoll and SpermPrep II increased MO (p < 0.01) where Sephadex reduced it (p = NS). Percoll and SpermPrep II improved the % of best quality sperm but not Sephadex with SpermPrep II being higher than Percoll. There were increases (p < 0.05) in HOS values in all experimental treatments with SpermPrep II being the best. However, this study did not show as many males with HOS scores below 50% as noted in other studies. Finally, Percoll and SpermPrep II seem equally effective methods for producing high quality sperm for IUI or IVF although SpermPrep II is quite faster.

Centrifugation, Density Gradient↗
PubMed1988

Protein kinase C activity and reactivity to phorbol ester in vascular smooth muscle from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY).

Protein kinase C (PKC) activity in aortic and renal arterial smooth muscle from SHR (20-23 wk male; mean arterial pressure = 178 mm Hg) and WKY (age/sex matched; mean arterial pressure = 126 mm Hg) was quantitated. Activity was greatest in the particulate fractions relative to the soluble fractions in all sources. The only difference between SHR and WKY was in the soluble fraction from SHR renal arteries, which had 2 fold more activity (255 pmol/mg/min) when compared with WKY (136 pmol/mg/min). This difference was not apparently related to force modulation, since the magnitude of isometric force development in renal arteries in response to phorbol 12,13-dibutyrate was not different between SHR and WKY. The magnitude of force developed in response to phorbol 12,13-dibutyrate and PKC activity in the particulate fraction was greatest in aorta vs. renal arteries in both WKY and SHR. These results suggest that regional vascular differences in the amount of PKC activity may exist which are not apparently related to a disease state (i.e., hypertension). These differences may be related to differential sensitivity to phorbol ester-mediated contractions in isolated smooth muscle.

Animals↗
PubMed1987

Tumors secreting human TNF/cachectin induce cachexia in mice.

Anorexia and weight loss are serious complications that adversely effect the prognosis of cancer patients. It has been suggested that TNF/cachectin may cause cachexia. To determine if TNF/cachectin can induce progressive weight loss in tumor-bearing animals, a clone of the human TNF/cachectin gene was isolated and inserted into a mammalian expression vector. This construct was transfected into CHO cells, and a cell line (CHO/TNF-20) that secretes TNF/cachectin was isolated. A cell line (CHO/CMV-Neo) that contains the same expression vector without the TNF/cachectin gene was also isolated. Nude mice injected intraperitoneally with CHO/TNF-20 cells died more quickly than mice injected with CHO/CMV-Neo cells. Eighty-seven percent of mice inoculated intramuscularly with CHO/TNF-20 cells developed severe cachexia and weight loss. All mice bearing CHO/CMV-Neo tumors maintained or increased their body weight. We conclude that mice bearing tumors that secrete TNF/cachectin develop progressive wasting and die more quickly than mice bearing control tumors.

Animals↗
PubMed1978

Characterization and purification of pregnancy-associated plasma protein B (PAPP-B).

PAPP-B is a pregnancy-specific beta 1-glycoprotein of large molecular weight, about 1,000,000 as determined by Sepharose 4B and 6B gel filtration. Its isoelectric point is between pH 4.6 and 5.0. It has been purified at least 800-fold from term pregnancy serum by a sequence of steps involving salting out at 30% saturation with ammonium sulfate (1,2M), DEAE-cellulose chromatography, Sepharose 4B gel filtration and hydroxylapatite chromatography. Monospecific antiserum to PAPP-B has been prepared, and used to differentiate it from several other newly reported tumor or pregnancy proteins. PAPP-B was found to increase slowly during the second trimester of pregnancy and more steeply during the third, reaching a plateau in late gestation. During the postpartum period, PAPP-B disappeared quite rapidly, with an apparent half-life of less than 1 day.

Blood Proteins↗
PubMed1976

Purification of group C streptococcal extracellular antigens detected with naturally occurring human antibodies: isolation of streptokinase and two previously undescribed antigens.

Twelve antigens were detected in crude group C streptococcal extracellular concentrates, using naturally occurring antibodies in normal human gamma globulin. These group C streptococcal antigens all appeared to be present in crude group A streptococcal extracellular concentrates, although the latter contained additional antigens reactive with the human antibodies. Systematic purification procedures were established for the isolation of the group C streptococcal antigens by a sequence of salting out, hydroxylapatite chromatography, Sephadex G-100 gel filtration, and isoelectric focusing. With such procedures, three of the group C streptococcal antigens were isolated in a relatively pure state. One of the purified antigens was identified as streptokinase on the basis of its fibrinolytic potency, its reaction of identity with two purified streptokinase fractions obtained from other sources, and its high titer in immunodiffusion assays. The most highly purified streptokinase fractions, derived from the 0.1 M sodium phosphate hydroxylapatite eluate, revealed a plasmin-inhibiting effect at high concentrations of streptokinase. This was not seen in the purified streptokinase of equivalent functional and immunological purity that was derived from the 0.2 M sodium phosphate hydroxylapatite peak. Two other streptococcal antigens were also isolated to a high degree during the course of the above study. These were designated antigens X and Y and were found to be unrelated immunologically to each other or to streptokinase. Their isoelectric points were 6.7 and 8.8, respectively, and both were present in group A streptococcal concentrates. Esterase activity was found to be widely distributed in almost all of the fractions obtained in the various purification steps, indicating a high degree of heterogeneity of the streptococcal enzyme. Histochemical staining techniques applied to the immune precipitates formed with human antibodies indicated that none of the antigens detected in crude group C and group A streptococcal concentrates possessed catalase, glucuronidase, glucosaminidase, acid or alkaline phosphatase, arylsulfatase, leucineaminopeptidase, or chymotrypsin enzymatic activities.

Antigen-Antibody Reactions↗