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C Renner

Publications and source records attributed to C Renner.

At least 73 records · Page 4Linked to original sources
PubMed1998

Backbone dynamics of the CDK inhibitor p19(INK4d) studied by 15N NMR relaxation experiments at two field strengths.

The four members of the INK4 gene family, p16(INK4a), p15(INK4b), p18(INK4c) and p19(INK4d), are known to bind to and inhibit the closely related cyclin-dependent kinases CDK4 and CDK6 as part of the regulation of the G1/S transition in the cell division cycle. Loss of INK4 gene product function, and particularly that of p16(INK4a), is found in human cancer. 15N NMR relaxation rates of p19(INK4d) were analyzed using the reduced spectral density mapping method. Most of the backbone of p19(INK4d) exists in a well-defined structure of limited conformational flexibility on the nanosecond to picosecond time-scales. Introducing appropriate scaling to account for the effects of anisotropy, a considerable amount of exchange broadening was found for several residues throughout the sequence, especially residues in the second ankyrin repeat and in the beginnings and ends of loops connecting ankyrin repeats. A possible mode of binding between p19(INK4d) and CDK4 and CDK6 could therefore involve the loop segments of p19(INK4d). The average overall correlation time taumeff was determined to be 13.6 ns, reflecting the tendency of p19(INK4d) to aggregate.

Anisotropy↗
PubMed1998

Epidural and pericranial abscesses complicating frontal sinusitis in a comatose child.

Most complications of sinusitis have a significant risk of severe morbidity and possibly mortality. Therefore a keen awareness of the subtle signs and symptoms of bacterial spread beyond the paranasal sinuses must be maintained. This increased awareness is especially important in mentally retarded and psychomotor handicapped children because they can develop a rapidly fatal course despite the absence of any warning signs.

Abscess↗
PubMed1998

Structure of interleukin 16 resembles a PDZ domain with an occluded peptide binding site.

The structure of a folded core of IL-16 is similar to that of intracellular protein modules called PDZ domains. IL-16 is thus the first extracellular protein found to have a PDZ-like fold. However, it does not exhibit normal peptide binding properties of PDZ domains. This is due to alterations of the structure at the 'PDZ-like binding site' of IL-16 (the GLGF cleft): the GLGF cleft of IL-16 is much smaller than those of PDZ-domains and is additionally blocked with a tryptophan side chain at its center. Our experiments indicate also that IL-16 nonspecifically aggregates in solution; but formation of a homo-tetrameric protein is not required, in contrast to previous suggestions, for its chemo-attractant activity.

Amino Acid Sequence↗
PubMed1998

Laser endopyelotomy: minimally invasive therapy of ureteropelvic junction stenosis.

Endoscopic pyelotomy is a minimally invasive procedure that is increasingly used for the management of ureteropelvic junction (UPJ) obstruction. We report the results and advantages in the management of UPJ obstruction using a ureteroscopic retrograde laser-assisted approach (laser endopyelotomy; LEP). Thirty-four patients were treated between December 1994 and June 1997 by this new technique. Twenty-seven obstructions were primary. The mean time of follow-up is 18 months. An indwelling ureteral catheter was placed 3 weeks prior to treatment. Intraoperatively, after the removal of the stent, a guidewire was passed across the stenosis, and the ureter was entered with a semirigid ureteroscope. The LEP was then performed under visual control using a contact laser fiber until all obstructive fibers had been cut. Follow-up examinations included sonography, intravenous urography, and, in unclear cases, a radionuclide renal scan with furosemide application after 3 months. The success rate was 85%. The most important factor influencing the outcome was the grade of hydronephrosis. Postoperative side effects have been minimal, and minor complications occurred in only 5 patients (15%). Laser endopyelotomy is a minimally invasive procedure with less morbidity for the treatment of UPJ obstruction. Only patients with a severe extrinsic cause of obstruction should be excluded from this technique. These cases can be approached laparoscopically.

Adolescent↗
PubMed1998

Progesterone inhibits glucocorticoid-dependent aromatase induction in human adipose fibroblasts.

In fibroblasts derived from human adipose tissue, aromatase induction is observed after exposure to 1 microM cortisol in the presence of serum or platelet-derived growth factor (PDGF). Progesterone suppresses this induction in a dose-dependent manner, 10 microM resulting in complete inhibition. A reduced cortisol concentration (0.1 microM) concomitantly reduces the progesterone concentration required for effective inhibition (10-100 nM). This effect of progesterone is specific, as neither the release of cellular enzymes nor aromatase induction by dibutyryl-cAMP, which acts independently from cortisol, are affected. However, the inhibitory effect of progesterone requires its presence throughout the induction period. Kinetic studies in intact cells reveal a reduced number of aromatase active sites upon progesterone treatment, whereas progesterone at near-physiological concentration (100 nM) does not inhibit aromatase activity in isolated microsomes. Semi-quantitative reverse transcriptase PCR analysis shows reduced amounts of aromatase mRNA in progesterone-treated cells, indicating specific inhibition of the glucocorticoid-dependent pathway of aromatase induction. The inhibitory effect of progesterone is not blocked by the anti-progestin ZK114043, excluding action via progesterone receptors and indicating competition for the glucocorticoid receptor. Progesterone must be considered a potential physiological inhibitor of glucocorticoid-dependent aromatase induction in adipose tissue. It is proposed that it is a suppressor of aromatase induction in adipose tissue in premenopausal women.

Adipocytes↗
PubMed1998

Anti-CD16/CD30 bispecific antibodies as possible treatment for refractory Hodgkin's disease.

Fifteen patients with refractory Hodgkin's disease were treated in a phase I/II dose escalation trial with the NK-cell activating bispecific monoclonal antibody HRS-3/A9 which is directed against the Fcgamma-receptor III (CD16 antigen) and the Hodgkin's associated CD30 antigen, respectively. HRS-3/A9 was given four times every 3-4 days starting with 1 mg/m2. The treatment was well tolerated and the maximum tolerated dose was not reached at 64 mg/m2, the highest dose given due to limited amounts of HRS-3/A9 available. Mild to moderate side effects occured in six patients and consisted of fever, pain in involved lymph nodes, and a maculopapulous rash. Median counts of NK-cells and of all lymphocyte subsets were considerably decreased in the patients before therapy and showed no consistent changes under therapy. Eight patients developed human anti-mouse immunoglobulin antibodies, and five patients showed an allergic reaction after attempted retreatment. One complete and one partial remission (lasting 6 and 3 months, respectively), three minor responses (lasting 1 to 15 months), two disease stabilizations (for 2 and 17 months, respectively), and one mixed response were achieved. There was no clearcut dose-side effect or dose-response correlation. Our results encourage further clinical trials with this novel immunotherapeutic approach and emphasize the necessity to reduce the immunogenicity of the murine bispecific antibodies.

Adult↗
PubMed1997

Ca2+-loaded spherulin 3a from Physarum polycephalum adopts the prototype gamma-crystallin fold in aqueous solution.

Spherulin 3a is the most abundantly expressed cytosolic protein in spherulating plasmodia of the slime mold Physarum polycephalum. High yields of unlabeled, uniformly 15N and uniformly 13C/15N-labeled recombinant spherulin 3a from Escherichia coli could be produced by a simple protocol described here. The three-dimensional solution structure of Ca2+-loaded spherulin 3a was determined by homo- and heteronuclear NMR spectroscopy. The structure of monomeric spherulin 3a consists of two pleated beta-sheets plus a short alpha-helix arranged into the gamma-crystallin fold. The beta-sheets comprise two intertwined Greek-key motifs. An additional N-terminal beta-strand is unique to spherulin 3a. Complexation of calcium ions greatly enhances overall conformational stability of the protein. The average atomic root-mean-square deviations (r.m.s.d.) for heavy atoms in beta-strands were 0.34(+/-0.16) A for the backbone atoms and 0.73(+/-0.40) A for all atoms. The corresponding r.m.s.d. values for heavy atoms in the whole protein were 0.62(+/-0.42) A for the backbone atoms and 0.99(+/-0.65) A for all atoms. We show the structural relationship between spherulin 3a, a myxomycete dormancy protein, and crystallins from the vertebrate eye lens. Since spherulin 3a has a structure corresponding to one domain of bovine gammaB(II)-crystallin, it represents a hypothetical ancestral gamma-crystallin precursor structure.

Amino Acid Sequence↗
PubMed1997

RP1, a new member of the adenomatous polyposis coli-binding EB1-like gene family, is differentially expressed in activated T cells.

Cross-linking of the CD3 and CD28 molecules on T lymphocytes represents one of the most effective signals for T lymphocyte activation and triggering of their cytotoxic effector function. To identify genes that are expressed in T cells after stimulation, mRNA from T lymphocytes that had been activated by the simultaneous stimulation of the CD3 and CD28 trigger molecules was transcribed for a differential mRNA display analysis into cDNA and was compared with cDNA from CD28- or CD3-activated or resting lymphocytes. Differential expression was confirmed subsequently by Northern blot analysis. One of the cDNA fragments expressed specifically in CD3- and CD28-activated T cells was designated RP1. The predictive protein-coding region of RP1 had a significant homology to members of the recently found adenomatous polyposis coli (APC) protein-binding EB1 gene family, which codes for yet unknown protein(s). Bacterially expressed RP1 protein revealed specific binding to wild-type but not to mutated APC protein. The rapid up-regulation of RP1 mRNA in properly activated T cells suggests that this gene might belong to the immediate/early gene family, which controls the signal transduction cascade downstream of the TCR. As the expression level of the RP1 gene in activated T cells and a spectrum of tumor-derived cell lines correlates with the proliferative status of the cells, members of the EB1-like gene family may not only be involved in the tumorigenesis of colorectal cancers but may also play a role in the proliferative control of normal cells.

Adenomatous Polyposis Coli↗
PubMed1997

Treatment of refractory Hodgkin's disease with an anti-CD16/CD30 bispecific antibody.

Fifteen patients with refractory Hodgkin's disease were treated in a phase I/II trial with the natural killer (NK)-cell-activating bispecific monoclonal antibody HRS-3/A9, which is directed against the Fc(gamma)-receptor III (CD16 antigen) and the Hodgkin's-associated CD30 antigen, respectively. Median counts of NK cells and of all lymphocyte subsets were considerably decreased in the patients before therapy. HRS-3/A9 was administered 4 times every 3 to 4 days, starting with 1 mg/m2. The treatment was well tolerated, and the maximum tolerated dose was not reached at 64 mg/m2, the highest dose administered because of the limited amounts of HRS-3/A9 available. Side effects were rare and consisted of fever, pain in involved lymph nodes, and a maculopapulous rash. A total of 9 patients developed human antimouse Ig antibodies, and 4 patients developed an allergic reaction after attempted retreatment. A total of 1 complete and 1 partial remission (lasting 6 and 3 months, respectively) [corrected], 3 minor responses (1 to 11+ months), and 1 mixed response were achieved. There was no clear-cut dose-side effect or dose-response correlation. Our results encourage further clinical trials with this novel immunotherapeutic approach and emphasize the necessity to reduce the immunogenicity of the murine bispecific antibodies.

Adolescent↗
PubMed1997

NMR structural characterization of the CDK inhibitor p19INK4d.

p19INK4d is a 165 amino acid protein that belongs to the INK4 family of CDK4 and CDK6 inhibitors. Assignments of 1H, 15N and 13C resonances have enabled the determination of the secondary structure of the protein which is largely alpha-helical (residues 14-18, 21-29, 54-62, 77-83, 87-95, 110-116, 120-128, 142-148 and 152-160). The protein comprises five 32-amino acid ankyrin-like repeats; each ankyrin repeat contains a helix-beta-turn-helix core. The exception is the second ankyrin repeat, which lacks the first helix. All beta-turns have a central glycine residue flanked by two residues in beta-conformations. There is also a high conservation of Ala at position 8 in the first helix and Leu-Leu(Val) at positions 17-18 of the second helix in all ankyrin repeats of p19. The location of the helix-turn-helix segments found in p19 should be general for all other members of the INK4 family, including, for example, a homologous tumor suppressor p16INK4a. 1H-15N heteronuclear steady-state NOE measurements on p19 indicate that most of the backbone of p19INK4d exists in a well defined structure of limited conformational flexibility on the nano- to picosecond time scale.

Amino Acid Sequence↗
PubMed1997

Reaction mechanism of Escherichia coli dihydrodipicolinate synthase investigated by X-ray crystallography and NMR spectroscopy.

Dihydrodipicolinate synthase (DHDPS) catalyzes the condensation of pyruvate with L-aspartate beta-semialdehyde. It is the first enzyme unique to the diaminopimelate pathway of lysine biosynthesis. Here we present the crystal structures of five complexes of Escherichia coli DHDPS with substrates, substrate analogs, and inhibitors. These include the complexes of DHDPS with (1) pyruvate, (2) pyruvate and the L-aspartate beta-semialdehyde analog succinate beta-semialdehyde, (3) the inhibitor alpha-ketopimelic acid, (4) dipicolinic acid, and (5) the natural feedback inhibitor L-lysine. The kinetics of inhibition were determined, and the binding site of the L-lysine was identified. NMR experiments were conducted in order to elucidate the nature of the product of the reaction catalyzed by DHDPS. By this method, (4S)-4-hydroxy-2,3,4,5-tetrahydro-(2S)-dipicolinic acid is identified as the only product. A reaction mechanism for DHDPS is proposed, and important features for inhibition are identified.

Bacterial Proteins↗
PubMed1997

Role of perforin, granzymes and the proliferative state of the target cells in apoptosis and necrosis mediated by bispecific-antibody-activated cytotoxic T cells.

Bispecific monoclonal antibodies (bi-mAb), directed against a tumor-associated antigen and the CD3 or CD28 antigen on T lymphocytes, induce activation of resting T lymphocytes and target-specific tumor cell lysis. We now show that both necrosis and apoptosis contribute to T-cell-mediated tumor cell destruction. Even though T cells up-regulate FAS/APO-1 expression upon bi-mAb stimulation, FAS/APO-1-mediated apoptosis does not contribute to bi-mAb-mediated destruction of Hodgkin's cells. CD8+ lymphocytes were the most potent effectors of bi-mAb-mediated cytotoxicity and had the highest levels of mRNA coding for perforin and granzyme A and B. Ca2+-complexing agents, which abrogate perforin activity, led to decreased levels of necrosis, while inhibition of granzyme activity in effector or target cells had a similar effect on apoptosis. Granzyme-mediated apoptosis critically dependent on the proliferative state of the target cells, while perforin-induced necrosis was not cell-cycle-dependent. Our results underline the importance of the expression levels of perforin and granzymes in the effector T cells and of the proliferative state of the target cells in bi-mAb-mediated apoptosis and necrosis of tumor cells.

Antibodies, Bispecific↗
PubMed1997

Role of naive and memory T cells in tumor cell lysis mediated by bi-specific antibodies.

Bispecific monoclonal antibodies (Bi-mAb) with specificity for a tumor associated antigen and the CD3 or CD28 antigen on T lymphocytes, respectively, induce activation of resting T lymphocytes and target-specific tumor cell lysis. Former studies had confirmed that T cells expressing the CD45RO "memory" antigen at high levels were the most potent effectors of Bi-mAb-mediated cytotoxicity when compared to their "naive" counterparts expressing the CD45RA antigen. Further analysis of the T cell subpopulations revealed that within the memory T cell pool, CD8+ T cells were the effector cell, population with strongest cytolytic activity. The cytolytic activity was correlated with the expression level of perforin and granzymes B mRNA. Ca2+ complexing agents, which abrogate perforin activity, reduced necrosis, while inhibition of granzyme activity in effector or target-cells had a similar effect on apoptosis. These results confirm the crucial role perforin and granzymes play in target-cell lysis and explain why CD8+CD45RO+ T cells activated by combined CD3 and CD28 antigen triggering represent the T cell pool with highest cytolytic potential.

Antibodies, Bispecific↗
PubMed1997

The repeating segments of the F-actin cross-linking gelation factor (ABP-120) have an immunoglobulin-like fold.

The 120,000 M(r) gelation factor and alpha-actinin are among the most abundant F-actin cross-linking proteins in Dictyostelium discoideum. Both molecules are rod-shaped homodimers. Each monomer chain is comprised of an actin-binding domain and a rod domain. The rod domain of the gelation factor consists of six 100-residue repetitive segments with high internal homology. We have now determined the three-dimensional structure of segment 4 of the rod domain of the gelation factor from D. discoideum using NMR spectroscopy. The segment consists of seven beta-sheets arranged in an immunoglobulin-like (Ig) fold. This is completely different from the alpha-actinin rod domain which consists of four spectrin-like alpha-helical segments. The gelation factor is the first example of an Ig-fold found in an actin-binding protein. Two highly homologous actin-binding proteins from human with similar sequences to the gelation factor, filamin and a 280,000 M(r) actin-binding protein (ABP-280), share conserved residues that form the core of the gelation factor repetitive segment structure. Thus, the segment 4 structure should be common to this subfamily of the spectrin superfamily. The structure of segment 4 together with previously published electron microscopy data, provide an explanation for the dimerization of the whole gelation factor molecule.

Actins↗
PubMed1997

Progesterone receptor gene expression in craniopharyngiomas and evidence for biological activity.

OBJECTIVE: Previous studies have demonstrated the presence of estrogen receptors in human craniopharyngiomas, raising the possibility that these lesions can be influenced by steroids. To complement these earlier findings, we examined for the presence of progesterone receptor (PR) messenger RNA in surgically removed craniopharyngiomas and performed some studies to determine whether progestogens can exert biological effects on these tumors in vitro. METHODS: Total RNA was extracted from fresh surgically removed craniopharyngiomas and reverse-transcribed into cDNA. The polymerase chain reaction was applied to this craniopharyngioma-derived cDNA using amplimers complementary to exons 4 and 7 of the PR gene. Additionally, craniopharyngioma cell cultures were established, and the in vitro effects of progesterone and 6 alpha-methyl-17 alpha-hydroxyprogesterone acetate on [3H]thymidine uptake and 17 beta-estradiol oxidoreductase activity were determined. RESULTS: Reversed-transcribed polymerase chain reaction of craniopharyngioma-derived RNA yielded bands of predicted size (389 base pairs) in six of seven tumors studied. Hinfl digestion and direct sequencing of the bands confirmed that the polymerase chain reaction DNA was representative of PR messenger RNA. Treatment of craniopharyngioma cell cultures with progesterone resulted in reduced [3H]thymidine uptake. Both progesterone and 6 alpha-methyl-17 alpha-hydroxyprogesterone acetate powerfully increased oxidative 17 beta-estradiol oxidoreductase activity. CONCLUSION: These results provide evidence that PR messenger RNA can be produced by at least some human craniopharyngiomas and indirectly show that this is translated into biologically active receptor protein.

Adolescent↗