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Biomedical subjects

G Rupp

Publications and source records attributed to G Rupp.

At least 19 recordsLinked to original sources
PubMed2001

The Chlamydomonas PF6 locus encodes a large alanine/proline-rich polypeptide that is required for assembly of a central pair projection and regulates flagellar motility.

Efficient motility of the eukaryotic flagellum requires precise temporal and spatial control of its constituent dynein motors. The central pair and its associated structures have been implicated as important members of a signal transduction cascade that ultimately regulates dynein arm activity. To identify central pair components involved in this process, we characterized a Chlamydomonas motility mutant (pf6-2) obtained by insertional mutagenesis. pf6-2 flagella twitch ineffectively and lack the 1a projection on the C1 microtubule of the central pair. Transformation with constructs containing a full-length, wild-type copy of the PF6 gene rescues the functional, structural, and biochemical defects associated with the pf6 mutation. Sequence analysis indicates that the PF6 gene encodes a large polypeptide that contains numerous alanine-rich, proline-rich, and basic domains and has limited homology to an expressed sequence tag derived from a human testis cDNA library. Biochemical analysis of an epitope-tagged PF6 construct demonstrates that the PF6 polypeptide is an axonemal component that cosediments at 12.6S with several other polypeptides. The PF6 protein appears to be an essential component required for assembly of some of these polypeptides into the C1-1a projection.

Algal Proteins↗
PubMed1998

[Surgical treatment of acute pericardial tamponade in an infestation of the heart by Echinococcus].

HISTORY AND CLINICAL FINDINGS: A 56-year-old turkish patient, previously in good health, was admitted because of pain suggesting myocardial infarction. Physical examination of the heart, lungs and abdomen was unremarkable. INVESTIGATIONS AND DIAGNOSIS: The concentrations of myocardium-specific enzymes were not elevated and the ECG showed no signs of ischaemia. Echocardiography and magnetic resonance imaging ruled out acute aortic dissection, but demonstrated a round cystic space-occupying mass over the anterior wall of the heart. Hydatid cyst was suspected from the imaging results and the patient's origin from area endemic for Echinococcus. The diagnosis was confirmed by a titre of 1:6,400 (normal: 1: < 100) for Echinococcus antibodies. TREATMENT AND COURSE: Albendazole administration was initiated. Planned elective surgical removal of the hysatid cyst had to be performed urgently because of acute pericardial tamponade. Cyst rupture was suspected but an actually undamaged cyst was subtotally removed under cardiopulmonary bypass. The postoperative course was uneventful and albendazole treatment was continued. CONCLUSION: Because of the high incidence of fatal complications urgent surgical removal under cardiopulmonary bypass is the treatment of choice for hydatid cyst involving the heart. Perioperative albendazole administration is also essential.

Acute Disease↗
PubMed1998

Toward healthy cities: opportunities for collaboration.

This paper locates the need for an urban health agenda in a broader social context. This broader context is characterized by increasing diversity and extensive privatization--developments that accentuate tendencies leading away from a shared sense of the common good. The paper then outlines ways that Columbia University seeks to work for healthier cities in this challenging context.

Cooperative Behavior↗
PubMed1998

Linear repair versus ventricular reconstruction for treatment of left ventricular aneurysm: a 10-year experience.

OBJECTIVE: To describe a 10-year experience with surgical treatment of left ventricular aneurysm and compare the results of linear repair and ventricular reconstruction. DESIGN: A retrospective data analysis. SETTING: Department of cardiothoracic surgery. PATIENTS: All patients treated with concurrent coronary artery bypass revascularization and surgical repair of ventricular aneurysm from 1985 to 1995. METHODS: Patients underwent either linear repair after aneurysmectomy (group A; n=51) or reconstruction of the left ventricle using a patch (group B, n=10). Preoperative patient characteristics and postoperative mortality and symptomatic results in the two groups were compared with chi(2) and paired "t"-tests. RESULTS: The early mortality rates were 9.8% overall, 7.8%, in group A, and 20% in group B. During a mean follow-up of 58 months, the late mortality rates were 34.5%, 38.2%, and 12.5%. In comparison to patients in group A, those in group B had higher preoperative rates of seriously impaired left ventricular ejection fraction (p=0.01) and pathologic left ventricular end-diastolic pressure (p=0.03) and a prolonged operative aortic cross-clamp time (p=0.04). Early mortality in group B may have been influenced by the initially impaired hemodynamic function and the cross-clamp time. In the longterm, patients in group B had more symptomatic improvement than those in group A (p=0.02). CONCLUSIONS: Ventricular function in patients with left ventricular aneurysm improved after ventricular reconstruction using a patch. Further experience with this procedure should improve postoperative survival and long-term prognosis.

Cardiac Surgical Procedures↗
PubMed1997

[The quadri-cusp aortic valve: a congenital defect, responsible for pathologic changes?].

We report on a 61-year-old patient with considerable insufficiency of a quadricuspid aortic valve and coronary three vessel disease. The congenital quadricuspid aortic valve has become symptomatic due to the development of (post-endocarditic) insufficiency only in the advanced stage of life. It was treated by replacement of the aortic valve and bypass myocardial revascularization. The physiopathology of quadricuspid aortic valve will be discussed.

Aortic Valve↗
PubMed1996

The sup-pf-2 mutations of Chlamydomonas alter the activity of the outer dynein arms by modification of the gamma-dynein heavy chain.

The sup-pf-2 mutation is a member of a group of dynein regulatory mutations that are capable of restoring motility to paralyzed central pair or radial spoke defective strains. Previous work has shown that the flagellar beat frequency is reduced in sup-pf-2, but little else was known about the sup-pf-2 phenotype (Huang, B., Z. Ramanis, and D.J.L. Luck. 1982. Cell. 28:115-125; Brokaw, C.J., and D.J.L. Luck. 1985. Cell Motil. 5:195-208). We have reexamined sup-pf-2 using improved biochemical and structural techniques and by the analysis of additional sup-pf-2 alleles. We have found that the sup-pf-2 mutations are associated with defects in the outer dynein arms. Biochemical analysis of sup-pf-2-1 axonemes indicates that both axonemal ATPase activity and outer arm polypeptides are reduced by 40-50% when compared with wild type. By thin-section EM, these defects correlate with an approximately 45% loss of outer dynein arm structures. Interestingly, this loss is biased toward a subset of outer doublets, resulting in a radial asymmetry that may reflect some aspect of outer arm assembly. The defects in outer arm assembly do not appear to result from defects in either the outer doublet microtubules or the outer arm docking structures, but rather appear to result from defects in outer dynein arm components. Analysis of new sup-pf-2 mutations indicates that the severity of the outer arm assembly defects varies with different alleles. Complementation tests and linkage analysis reveal that the sup-pf-2 mutations are alleles of the PF28/ODA2 locus, which is thought to encode the gamma-dynein heavy chain subunit of the outer arm. The sup-pf-2 mutations therefore appear to alter the activity of the outer dynein arms by modification of the gamma-dynein heavy chain.

Alleles↗
PubMed1995

Outer arm dynein from Newt lung respiratory cilia: purification and polypeptide composition.

Dyneins are multimeric ATPases that comprise the inner and outer arms of cilia and flagella. It previously has been shown that salt extraction of newt lung axonemes selectively removes > 95% of the outer arm dynein (OAD), and that the beat frequency of OAD-depleted axonemes cannot be activated as compared to controls [Hard et al., 1992: Cell Motil. Cytoskeleton 21:199-209]. Therefore, expression of the activated state appears to require the presence of outer dynein arms. The present study was undertaken to ascertain basic information on the structure and molecular composition of newt OAD. Populations of demembranated axonemes were extracted with 0.375 M salt. Each lung released approximately 1.4 x 10(7) axonemes during isolation, yielding approximately 120 ng of salt extractable OAD. Electron microscopy of negatively stained samples revealed that newt OAD consisted of two globular heads joined together by a Y-shaped stem, similar to sea urchin and trout sperm OAD. Each head appeared to be roughly spherical in shape, measuring approximately 17 nm in diameter. Electrophoretic analysis of whole axonemes revealed more than six dynein heavy chains when resolved in silver stained 0-8 M urea, 3-5% acrylamide gradients. Extracted OAD, either crude in high salt or purified by alloaffinity, was composed of two heavy chains. UV-induced (366 nm) photolytic cleavage at the V1 site, performed in the presence of Mg2+, vanadate, and ATP, produced four new polypeptides (M(r) 234, 232, 197, and 189 kD). Photolysis was supported by Mg2+ and Ca2+, but did not occur in the presence of Mn2+. The apparent M(r) of the dynein heavy chains was determined to lie between 430-420 kD. Eight discrete polypeptides (putative intermediate chains, IC1-IC8, M(r), 175-56 kD) copurified with the alpha- and beta-heavy chains by microtubule-alloaffinity. Based on its extraction characteristics, polypeptide composition in purified and crude samples, and structure, we conclude that this two-headed particle represents the entire newt respiratory outer arm dynein.

Amino Acid Sequence↗
PubMed1993

Glycoprotein 2 of zymogen granule membranes shares immunological cross-reactivity and sequence similarity with phospholipase A2.

Glycoprotein 2 (GP2), the major protein of rat pancreatic zymogen granule membranes (ZGMs), cross-reacted with an antiserum against porcine secretory phospholipase A2 (sPLA2). Amino acid sequence comparison showed 45% similarity and 23% identity between porcine PLA2 and the C-terminal portion of GP2. An antiserum to intestinal brush border Ca(2+)-independent PLA2 (bbPLA2) also recognized GP2. The antigenic and sequence similarities between GP2, sPLA2, and bbPLA2 imply that the role of GP2 in cellular function is associated with phospholipid binding and/or hydrolysis.

Amino Acid Sequence↗
PubMed1992

Immunocytochemical staining of fine-needle aspiration biopsies of the liver as a diagnostic tool for hepatocellular carcinoma.

Fine-needle aspiration biopsy (FNAB) under ultrasonographic or computerized tomographic guidance is a useful diagnostic procedure for hepatic neoplasms. However, cytologic criteria alone may not allow for the distinction of hepatocellular carcinomas (HCC) from cholangiocarcinomas (CC) and metastatic adenocarcinomas (MA). In an effort to refine the FNAB diagnosis of hepatic malignancies, a panel of immunocytochemical stains was applied to aspiration specimens from primary and metastatic carcinomas in the liver. Anticytokeratin antibodies with different specificities (Cam 5.2 and AE1) were used in conjunction with antibodies to carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and alpha-1-antitrypsin (AAT). All HCC, CC, and MA were immunoreactive with the antikeratin antibody Cam 5.2. However, only three (15%) HCC were positive with AE1, in contrast to 100% of CC and MA. Antibodies to CEA and AFP were also helpful diagnostic aids, especially for the three HCC that were immunoreactive with AE1. Canalicular staining for CEA was present in 47% of HCC, but in none of the CC or MA. AFP positivity occurred in 45% of HCC, but only one CC and none of the MA. AAT was not a useful marker for HCC due to low sensitivity and specificity. Immunocytochemistry is an effective adjunct to the cytodiagnosis of malignant liver tumors sampled by FNAB.

Biopsy, Needle↗
PubMed1990

Diffuse kinetochores and holokinetic anaphase chromatin movement during mitosis in the hemipteran Agallia constricta (leafhopper) cell line AC-20.

Mitosis in the hemipteran Agallia constricta (leafhopper) cell line AC-20 was examined by light microscopy of living and fixed cells. During early prometaphase the numerous small (0.30-3.0-microns) chromosomes appear as discrete units that lack a primary constriction. However, by late prometaphase the chromosomes are tightly packed at the spindle equator and are no longer clearly resolvable as individuals. When viewed from the side the metaphase chromatin appears as a 2-3-microns wide band that spans the width of the spindle; when viewed from the pole it appears as a fenestrated disk. The metaphase chromatin splits at anaphase into two sister chromatin plates, each of which exhibits holokinetic poleward movement, i.e., all parts of each plate move as a single unit with the same velocity. In many early-to-mild anaphase cells the separating sister plates are connected by chromatin-containing bridges that break as anaphase progresses. Ultrastructural analyses of serial thick and thin sections from cells fixed by conventional, OsO4/KFeCN, or high pressure rapid freezing methods, reveal that by metaphase all of the chromosomes are interconnected to form a large, irregularly shaped fenestrated disk of chromatin. Similar analyses reveal that adjacent chromatids remain interconnected throughout anaphase. Each disk of metaphase and anaphase chromatin contains numerous kinetochores recessed within its pole-facing surface. Kinetochores consist of a fine, faintly staining fibrillar material arranged along the chromatin surface as thin (0.1-0.3 micron dia.) rods varying considerably (0.15-2.3 microns) in length. From these observations we conclude that the polycentric metaphase chromatin of A. constricta, and its holokinetic behavior during anaphase, arises from the aggregation or cohesion of smaller prometaphase chromosomes, each of which contains a single, diffuse kinetochore.

Anaphase↗
PubMed1990

Stability of microtubule attachment to metaphase kinetochores in PtK1 cells.

Kinetochore microtubules are known to be differentially stable to a variety of microtubule depolymerization agents compared to the non-kinetochore polar microtubules, but the dynamics of microtubule attachment to the kinetochore is currently controversial. We have examined the stability of kinetochore microtubules in metaphase PtK1 spindles at 23 degrees C when microtubule assembly is abruptly blocked with the drug nocodazole. Metaphase cells were incubated in medium containing 34 microM nocodazole for various times before fixation and processing either for immunofluorescence light microscopy or serial-section electron microscopy. Microtubules not associated with kinetochore fibers disappeared completely in less than 1 min. Kinetochore fibers persisted and shortened, as the spindle poles moved close to the chromosomes over a 10-20 min interval. During this shortening process, the number of kinetochore microtubules decreased slowly. The mean number of kinetochore microtubules was 24 +/- 5 in control cells and zero in cells incubated with nocodazole for 20 min. The half-time of microtubule attachment to the kinetochore was approximately 7.5 min. These results show that when microtubule assembly is blocked, kinetochore microtubules shorten more slowly and persist about 10 times longer than the labile polar microtubules. If kinetochore microtubules shorten by tubulin dissociation at their plus-ends like the non-kinetochore polar microtubules, then the microtubule surface lattice must be able to translocate through the kinetochore attachment site without frequent detachment occurring.

Animals↗
PubMed1989

Molecular analysis of the rat MHC. II. Isolation of genes that map to the RT1.E-grc region.

An initial mapping analysis of growth and reproduction complex (grc) and grc+ genomic DNA identified several restriction fragment length polymorphisms specific for the grc region of the MHC. To analyze further the genomic organization and structure of the grc, a cosmid library was constructed from a grc+-bearing strain (R21). One cosmid cluster, encompassing 41.4 kb of DNA, contained four, or possibly five, class I genes that mapped to the RT1.E-grc region Two unique non-class I fragments were isolated from certain cosmids within this cluster. These fragments were hybridized to genomic DNA derived from five rat strains (BIL/2, R18, R21, R22, and BIL/1), and the results showed that grc-bearing rats have a deletion of at least 3.1 kb of DNA in the region immediately adjacent to the MHC. The loss of the genes in this region is probably the cause of the growth and reproductive defects in these animals and probably also of their increased susceptibility to chemical carcinogens.

Animals↗
PubMed1989

Biotin-tubulin incorporates into kinetochore fiber microtubules during early but not late anaphase.

The dynamic behavior of kinetochore fiber microtubules has been examined in PtK1 cells during anaphase of mitosis. Cells in anaphase were injected with biotin-tubulin and, at various intervals after injection, fixed for light or electron microscopic immunolocalization of biotin-tubulin-containing microtubules. When cells in early to mid anaphase were injected with biotin-tubulin and fixed 1-2 min later, fluorescence was observed throughout the spindle, including the region of the kinetochore fibers. Electron microscopy of early to mid anaphase cells, after processing with immunogold methods, revealed both labeled and unlabeled microtubules in the kinetochore fibers; some labeled microtubules contacted the kinetochores. When late anaphase cells were injected with biotin-tubulin, and fixed a few minutes later, little fluorescence was observed in the kinetochore fibers. Electron microscopy confirmed that kinetochore fibers in late anaphase cells were refractory to tubulin incorporation. The results of these experiments demonstrate that the kinetochore fiber incorporates new microtubules during early anaphase but that this incorporation ceases in mid to late anaphase. Thus, microtubule turnover within the kinetochore fiber does not abruptly cease at the onset of anaphase and anaphase kinetochore fiber microtubules are more dynamic than previously suspected.

Anaphase↗
PubMed1989

Mechanically cut mitotic spindles: clean cuts and stable microtubules.

We have discovered an easy way to cut through the mitotic spindle at any desired place. Spindles of demembranated cricket or grasshopper spermatocytes were severed with a microneedle between the chromosomes and one pole, and the cut-off polar piece was swept away. Spindle structure and microtubule dynamics in cut spindles were studied by anti-tubulin immunostaining and electron microscopy. The cut is clean: all microtubules are severed and only a few extend beyond the others. This provides the basis for a clear test of whether traction fibers pull chromosomes to the pole in anaphase, because the putative traction fiber is cleanly severed. Cutting creates new plus ends on microtubules in the cut-off polar piece and new minus ends on microtubules in the main spindle body. The microtubules with new plus ends are unstable, as expected from the dynamic instability of microtubules. However, the microtubules with new minus ends are as stable as uncut microtubules in the same spindle. Our mechanical method of cutting microtubules very likely creates native, reactive ends, and therefore the surprising stability of new minus ends is genuinely interesting, not an artifact of cutting.

Animals↗
PubMed1986

Naturally occurring tubulin-containing paracrystals in Allogromia: immunocytochemical identification and functional significance.

Bundles of microtubules (MTs) are readily visualized in vivo by videomicroscopy in highly flattened reticulopodia of the foraminiferan protozoan Allogromia sp. strain NF. In this report we use videomicroscopy, immunocytochemistry, and high-voltage electron microscopy to characterize the dynamic changes that occur in this extensive MT cytoskeleton, and in the associated cytoplasmic transport, during induced withdrawal and subsequent reextension of reticulopodia. Within seconds after application of the withdrawal stimulus (seawater substitute made hypertonic with MgCl2) intracellular bidirectional transport along linear MT-containing fibrils ceases and is replaced by an inward, constant-velocity flow of cytoplasm along the fibrils. As withdrawal continues, most fibrils become wavy and coalesce to form phase-dense pools. These wavy fibrils and phase-dense pools contain a paracrystalline material and few if any MTs. Same-section correlative immunofluorescence and high-voltage electron microscopy reveal that the paracrystalline material contains tubulin. During recovery linear fibrils (MTs) rapidly extend from the phase-dense pools (paracrystals), which concurrently shrink in size, thus reestablishing normal network morphology and motility. We conclude that the MT cytoskeleton in Allogromia reticulopodia is transformed during withdrawal into a tubulin-containing paracrystal, which serves as a temporary reservoir of MT protein and an initiation site for MT regrowth.

Animals↗