Intramural leiomyoma during pregnancy becoming pedunculated postpartally. A case report

BACKGROUND

The natural history of uterine leiomyomas during pregnancy has been reported.

CASE

A 39-year-old primigravida presented with vaginal spotting in the 10th week of pregnancy. Ultrasonic evaluation revealed a large intramural leiomyoma. Unsuccessful tocolysis at 25 weeks' gestation resulted in a cesarean section for breech presentation. At hysterotomy a 10-cm intramural leiomyoma was found in the right fundus and was left in situ. Six months later, at open laparotomy for myomectomy, the 10-cm leiomyoma was pedunculated, on a 4-cm stalk.

CONCLUSION

Large intramural leiomyomas found at cesarean section may become pedunculated postpartally, thus making myomectomy easier and safer at a postpartum intervention than at the time of cesarean section. Also, prior knowledge of the possibility of myoma transformation from intramural to pedunculated postpartally may help in planning a later myomectomy. Myomectomy prior to pregnancy should be considered when it has caused a prior pregnancy complication.

Covering dynamical systems: twofold covers

We study the relation between a dynamical system, which is unchanged (equivariant) under a discrete symmetry group G and another locally identical dynamical system with no residual symmetry. We also study the converse mapping: lifting a dynamical system without symmetry to a multiple cover, which is equivariant under G. This is done in R3 for the two element rotation and inversion groups. Comparisons are done for the equations of motion, the strange attractors that they generate, and the branched manifolds that classify these strange attractors. A dynamical system can have many inequivalent multiple covers, all equivariant under the same symmetry group G. These are distinguished by the value of a certain topological index. Many examples are presented. A new global bifurcation, the "peeling bifurcation," is described.

Role of the cytoplasmic segments of Sec61alpha in the ribosome-binding and translocation-promoting activities of the Sec61 complex

The Sec61 complex performs a dual function in protein translocation across the RER, serving as both the high affinity ribosome receptor and the translocation channel. To define regions of the Sec61 complex that are involved in ribosome binding and translocation promotion, ribosome-stripped microsomes were subjected to limited digestions using proteases with different cleavage specificities. Protein immunoblot analysis using antibodies specific for the NH(2) and COOH terminus of Sec61alpha was used to map the location of proteolysis cleavage sites. We observed a striking correlation between the loss of binding activity for nontranslating ribosomes and the digestion of the COOH- terminal tail or cytoplasmic loop 8 of Sec61alpha. The proteolyzed microsomes were assayed for SRP-independent translocation activity to determine whether high affinity binding of the ribosome to the Sec61 complex is a prerequisite for nascent chain transport. Microsomes that do not bind nontranslating ribosomes at physiological ionic strength remain active in SRP-independent translocation, indicating that the ribosome binding and translocation promotion activities of the Sec61 complex do not strictly correlate. Translocation-promoting activity was most severely inhibited by cleavage of cytosolic loop 6, indicating that this segment is a critical determinant for this function of the Sec61 complex.

Role of Sec61alpha in the regulated transfer of the ribosome-nascent chain complex from the signal recognition particle to the translocation channel

Targeting of ribosome-nascent chain complexes to the translocon in the endoplasmic reticulum is mediated by the concerted action of the signal recognition particle (SRP) and the SRP receptor (SR). Ribosome-stripped microsomes were digested with proteases to sever cytoplasmic domains of SRalpha, SRbeta, TRAM, and the Sec61 complex. We characterized protein translocation intermediates that accumulate when Sec61alpha or SRbeta is inactivated by proteolysis. In the absence of a functional Sec61 complex, dissociation of SRP54 from the signal sequence is blocked. Experiments using SR proteoliposomes confirmed the assembly of a membrane-bound posttargeting intermediate. These results strongly suggest that the Sec61 complex regulates the GTP hydrolysis cycle of the SRP-SR complex at the stage of signal sequence dissociation from SRP54.

Role of ubiquitin in proteasomal degradation of mutant alpha(1)-antitrypsin Z in the endoplasmic reticulum

A delay in intracellular degradation of the mutant alpha(1)-antitrypsin (alpha(1)AT)Z molecule is associated with greater retention within the endoplasmic reticulum (ER) and susceptibility to liver disease in a subgroup of patients with alpha(1)AT deficiency. Recent studies have shown that alpha(1)ATZ is ordinarily degraded in the ER by a mechanism that involves the proteasome, as demonstrated in intact cells using human fibroblast cell lines engineered for expression of alpha(1)ATZ and in a cell-free microsomal translocation assay system programmed with purified alpha(1)ATZ mRNA. To determine whether the ubiquitin system is required for proteasomal degradation of alpha(1)ATZ and whether specific components of the ubiquitin system can be implicated, we have now used two approaches. First, we overexpressed a dominant-negative ubiquitin mutant (UbK48R-G76A) by transient transfection in the human fibroblast cell lines expressing alpha(1)ATZ. The results showed that there was marked, specific, and selective inhibition of alpha(1)ATZ degradation mediated by UbK48R-G76A, indicating that the ubiquitin system is at least in part involved in ER degradation of alpha(1)ATZ. Second, we subjected reticulocyte lysate to DE52 chromatography and tested the resulting well-characterized fractions in the cell-free system. The results showed that there were both ubiquitin-dependent and -independent proteasomal mechanisms for degradation of alpha(1)ATZ and that the ubiquitin-conjugating enzyme E2-F1 may play a role in the ubiquitin-dependent proteasomal mechanism.

Strategies for successful management of older patients with seizures

The incidence of seizures increases dramatically with age, making epilepsy in the older patient a common clinical presentation in the primary care practice. In the case of a single seizure or when the underlying cause can be corrected, antiepileptic drug (AED) therapy may not be warranted. For recurrent seizures, single AED therapy should be initiated at a low dose and gradually titrated upward. Control of seizure frequency is dependent on appropriate AED selection and compliance, drug-drug interactions, and minimization of side effects. Monitoring of AED serum levels is imperative for effective AED therapy. Conventional AEDs remain the standard initial anticonvulsants for epilepsy in older patients. The newer AEDs have demonstrated efficacy as adjunctive therapy and may offer reduced side-effect profiles and fewer drug-drug interactions.

Adult-onset seizures: clinical solutions to a challenging patient work-up

The age-related increase in the incidence of seizures in older persons is directly related to the increase in prevalence of causative factors such as cardiovascular disease and stroke, primary and metastatic brain tumors, toxic-metabolic disturbances, and medications. Because the treatment plan depends on seizure etiology, comprehensive evaluation of each of these causes is imperative. Reliable history and thorough physical examination remain the most important steps for diagnosis and effective treatment. Nevertheless, assessment and treatment of new-onset paroxysmal events can be problematic, because numerous morbidities and syndromes--including transient ischemic attack, syncope, drug intoxication, amnesia, movement disorders, and psychiatric disorders--can present with similar symptomology.

Conduction aphasia and the arcuate fasciculus: A reexamination of the Wernicke-Geschwind model

Wernicke, and later Geschwind, posited that the critical lesion in conduction aphasia is in the dominant hemisphere's arcuate fasciculus. This white matter pathway was thought to connect the anterior language production areas with the posterior language areas that contain auditory memories of words (a phonological lexicon). Alternatively, conduction aphasia might be induced by cortical dysfunction, which impairs the phonological output lexicon. We observed an epileptic patient who, during cortical stimulation of her posterior superior temporal gyrus, demonstrated frequent phonemic paraphasias, decreased repetition of words, and yet had intact semantic knowledge, a pattern consistent with conduction aphasia. These findings suggest that cortical dysfunction alone may induce conduction aphasia.

Topological analysis of chaos in neural spike train bursts

We show how a topological model which describes the stretching and squeezing mechanisms responsible for creating chaotic behavior can be extracted from the neural spike train data. The mechanism we have identified is the same one ("gateau roule," or jelly-roll) which has previously been identified in the Duffing oscillator [Gilmore and McCallum, Phys. Rev. E 51, 935 (1995)] and in a YAG laser [Boulant et al., Phys. Rev. E 55, 5082 (1997)]. (c) 1999 American Institute of Physics.

A role for the DnaJ homologue Scj1p in protein folding in the yeast endoplasmic reticulum

Members of the eukaryotic heat shock protein 70 family (Hsp70s) are regulated by protein cofactors that contain domains homologous to bacterial DnaJ. Of the three DnaJ homologues in the yeast rough endoplasmic reticulum (RER; Scj1p, Sec63p, and Jem1p), Scj1p is most closely related to DnaJ, hence it is a probable cofactor for Kar2p, the major Hsp70 in the yeast RER. However, the physiological role of Scj1p has remained obscure due to the lack of an obvious defect in Kar2p-mediated pathways in scj1 null mutants. Here, we show that the Deltascj1 mutant is hypersensitive to tunicamycin or mutations that reduce N-linked glycosylation of proteins. Although maturation of glycosylated carboxypeptidase Y occurs with wild-type kinetics in Deltascj1 cells, the transport rate for an unglycosylated mutant carboxypeptidase Y (CPY) is markedly reduced. Loss of Scj1p induces the unfolded protein response pathway, and results in a cell wall defect when combined with an oligosaccharyltransferase mutation. The combined loss of both Scj1p and Jem1p exaggerates the sensitivity to hypoglycosylation stress, leads to further induction of the unfolded protein response pathway, and drastically delays maturation of an unglycosylated reporter protein in the RER. We propose that the major role for Scj1p is to cooperate with Kar2p to mediate maturation of proteins in the RER lumen.

Prevalence of Coxiella burnetii infections among North Dakota sheep producers

A case of Q fever in a sheep producer was detected by a surveillance system in North Dakota in 1993, when Q fever was not reportable. This is the first officially documented case in the state. To estimate the prevalence of Coxiella burnetii infection and identify associated risk factors, we conducted a study covering the whole state. A total of 17 cases were identified among 496 sheep producers, their family members, and hired helpers. The number of sheep raised was a good predictor of C. burnetii infection. Lambing outdoors and frequent physical contacts with sheep during lambing were associated with a higher risk, but petting dogs was correlated with a lower risk. We conclude that C. burnetii infection is prevalent among sheep producers in North Dakota. As the result, Q fever became a reportable disease in North Dakota.

Chemokines are present in the genital tract of HIV-seropositive and HIV-seronegative women: correlation with other immune mediators

In this cross-sectional study, 53 cervicovaginal lavage samples (CVL) from 41 women were analyzed for the chemokines interleukin-8 (IL-8), regulated-on-activation normal T-expressed and secreted (RANTES) factor, and macrophage inflammatory protein-1alpha (MIP-1alpha) by enzyme-linked immunosorbent assay (ELISA). IL-8 was detected in 81% of CVL, whereas RANTES was detected in 32%, and MIP-1alpha in 15% of the CVL. The mean levels of IL-8, RANTES, and MIP-1alpha in positive samples were 396 pg/ml, 102 pg/ml, and 34 pg/ml, respectively. IL-8 levels correlated positively with IL-1beta and IgG in a subset of CVL samples. RANTES levels correlated positively with complement protein levels. Additionally, the levels of RANTES, but not MIP-1alpha, reached levels reported in previous studies of the effects of beta chemokines to inhibit HIV replication. These results suggest that measuring chemokines in CVL specimens can provide important information regarding immune responses in the genital tract.

Active participation of Hsp90 in the biogenesis of the trimeric reovirus cell attachment protein sigma1

The reovirus cell attachment protein, sigma1, is a lollipop-shaped homotrimer with an N-terminal fibrous tail and a C-terminal globular head. Biogenesis of this protein involves two trimerization events: N-terminal trimerization, which occurs cotranslationally and is Hsp70/ATP-independent, and C-terminal trimerization, which occurs posttranslationally and is Hsp70/ATP-dependent. To determine if Hsp90 also plays a role in sigma1 biogenesis, we analyzed sigma1 synthesized in rabbit reticulocyte lysate. Coprecipitation experiments using anti-Hsp90 antibodies revealed that Hsp90 was associated with immature sigma1 trimers (hydra-like intermediates with assembled N termini and unassembled C termini) but not with mature trimers. The use of truncated sigma1 further demonstrated that only the C-terminal half of sigma1 associated with Hsp90. In the presence of the Hsp90 binding drug geldanamycin, N-terminal trimerization proceeded normally, but C-terminal trimerization was blocked. Geldanamycin did not inhibit the association of Hsp90 with sigma 1 but prevented the subsequent release of Hsp90 from the immature sigma1 complex. We also examined the status of p23, an Hsp90-associated cochaperone. Like Hsp90, p23 only associated with immature sigma1 trimers, and this association was mapped to the C-terminal half of sigma1. However, unlike Hsp90, p23 was released from the sigma1 complex upon the addition of geldanamycin. These results highlight an all-or-none concept of chaperone involvement in different oligomerization domains within a single protein and suggest a possible common usage of chaperones in the regulation of general protein folding and of steroid receptor activation.

An efficient motion estimator with application to medical image registration

Image registration is a very important problem in computer vision and medical image processing. Numerous algorithms for registering single and multi-modal image data have been reported in these areas. Robustness as well as computational efficiency are prime factors of importance in image data registration. In this paper, a robust/reliable and efficient algorithm for estimating the transformation between two image data sets of a patient taken from the same modality over time is presented. Estimating the registration between two image data sets is formulated as a motion-estimation problem. We use a hierarchical optical flow motion model which allows for both global as well as local motion between the data sets. In this hierarchical motion model, we represent the flow field with a B-spline basis which implicitly incorporates smoothness constraints on the field. In computing the motion, we minimize the expectation of the squared differences energy function numerically via a modified Newton iteration scheme. The main idea in the modified Newton method is that we precompute the Hessian of the energy function at the optimum without explicitly knowing the optimum. This idea is used for both global and local motion estimation in the hierarchical motion model. We present examples of motion estimation on synthetic and real data (from a patient acquired during pre- and post-operative stages) and compare the performance of our algorithm with that of competing ones.

Signal recognition particle-dependent targeting of ribosomes to the rough endoplasmic reticulum in the absence and presence of the nascent polypeptide-associated complex

Proteins with RER-specific signal sequences are cotranslationally translocated across the rough endoplasmic reticulum through a proteinaceous channel composed of oligomers of the Sec61 complex. The Sec61 complex also binds ribosomes with high affinity. The dual function of the Sec61 complex necessitates a mechanism to prevent signal sequence-independent binding of ribosomes to the translocation channel. We have examined the hypothesis that the signal recognition particle (SRP) and the nascent polypeptide-associated complex (NAC), respectively, act as positive and negative regulatory factors to mediate the signal sequence-specific attachment of the ribosome-nascent chain complex (RNC) to the translocation channel. Here, SRP-independent translocation of a nascent secretory polypeptide was shown to occur in the presence of endogenous wheat germ or rabbit reticulocyte NAC. Furthermore, SRP markedly enhanced RNC binding to the translocation channel irrespective of the presence of NAC. Binding of RNCs, but not SRP-RNCs, to the Sec61 complex is competitively inhibited by 80S ribosomes. Thus, the SRP-dependent targeting pathway provides a mechanism for delivery of RNCs to the translocation channel that is not inhibited by the nonselective interaction between the ribosome and the Sec61 complex.

The highly conserved Stt3 protein is a subunit of the yeast oligosaccharyltransferase and forms a subcomplex with Ost3p and Ost4p

The oligosaccharyltransferase has been purified from Saccharomyces cerevisiae as an hetero-oligomeric complex composed of four or six subunits. Here, the in vivo subunit composition and stoichiometry of the oligosaccharyltransferase were investigated by attaching an epitope coding sequence to a previously characterized subunit gene, OST3. Five (Ost1p, Wbp1p, Swp1p, Ost2p, and Ost5p) of the seven polypeptides that were coimmunoprecipitated with the epitope-tagged Ost3p were identical to those obtained by the conventional purification procedure. Two additional coprecipitating polypeptides with apparent molecular masses of 60 and 3.6 kDa were identified as the 78-kDa Stt3 protein and the 36-residue Ost4 protein, respectively. Stt3p and Ost4p were previously identified in screens for gene products involved in N-linked glycosylation. Quantification of the in vivo radiolabeled subunits and the radioiodinated purified enzyme shows that the yeast oligosaccharyltransferase is composed of equimolar amounts of eight subunits. Exposure of the immunoprecipitated oligosaccharyltransferase to mild protein denaturants yielded a subcomplex comprised of Stt3p, Ost3p, and Ost4p. These experiments, taken together with genetic and biochemical evidence for subunit interactions, suggest that the enzyme is composed of the following three subcomplexes: (a) Stt3p-Ost4p-Ost3p, (b) Swp1p-Wbp1p-Ost2p, and (c) Ost1p-Ost5p.

Empty site forms of the SRP54 and SR alpha GTPases mediate targeting of ribosome-nascent chain complexes to the endoplasmic reticulum

The SRP54 and SR alpha subunits of the signal recognition particle (SRP) and the SRP receptor (SR) undergo a tightly coupled GTPase cycle that mediates the signal sequence-dependent attachment of ribosomes to the Sec61 complex. Here, we show that SRP54 and SR alpha are in the empty site conformation prior to contact between the SRP-ribosome complex and the membrane-bound SR. Cooperative binding of GTP to SRP54 and SR alpha stabilizes the SRP-SR complex and initiates signal sequence transfer from SRP54 to Sec61 alpha. The GTP-bound conformations of SR alpha and SRP54 perform distinct roles, with SR alpha performing a predominant role in complex stabilization. Hydrolysis by both SRP54 and SR alpha is a prerequisite for dissociation of the SRP-SR complex.

DAD1, the defender against apoptotic cell death, is a subunit of the mammalian oligosaccharyltransferase

DAD1, the defender against apoptotic cell death, was initially identified as a negative regulator of programmed cell death in the BHK21-derived tsBN7 cell line. Of interest, the 12.5-kDa DAD1 protein is 40% identical in sequence to Ost2p, the 16-kDa subunit of the yeast oligosaccharyltransferase (OST). Although the latter observation suggests that DAD1 may be a mammalian OST subunit, biochemical evidence to support this hypothesis has not been reported. Previously, we showed that canine OST activity is associated with an oligomeric complex of ribophorin I, ribophorin II, and OST48. Here, we demonstrate that DAD1 is a tightly associated subunit of the OST both in the intact membrane and in the purified enzyme. Sedimentation velocity analyses of detergent-solubilized WI38 cells and canine rough microsomes show that DAD1 cosediments precisely with OST activity and with the ribophorins and OST48. Radioiodination of the purified OST reveals that DAD1 is present in roughly equimolar amounts relative to the other subunits. DAD1 can be crosslinked to OST48 in intact microsomes with dithiobis(succinimidylpropionate). Crosslinked ribophorin II-OST48 heterodimers, DAD1-ribophorin II-OST48 heterotrimers and DAD1-ribophorin I-ribophorin II-OST48 heterotetramers also were detected. The demonstration that DAD1 is a subunit of the OST suggests that induction of a cell death pathway upon loss of DAD1 in the tsBN7 cell line reflects the essential nature of N-linked glycosylation in eukaryotes.

A specific screen for oligosaccharyltransferase mutations identifies the 9 kDa OST5 protein required for optimal activity in vivo and in vitro

The central reaction in the process of N-linked protein glycosylation in eukaryotic cells, the transfer of the oligosaccharide Glc(3)Man(9)GlcNAc(2) from the lipid dolicholpyrophosphate to selected asparagine residues, is catalyzed by the oligosaccharyltransferase (OTase). This enzyme consists of multiple subunits; however, purification of the complex has revealed different results with respect to its protein composition. To determine how many different loci are required for OTase activity in vivo, we performed a novel, specific screen for mutants with altered OTase activity. Based on the synthetic lethal phenotype of OTase mutants in combination with a deficiency of dolicholphosphoglucose biosynthesis which results in non-glucosylated lipid-linked oligosaccharide, we identified seven complementation groups with decreased OTase activity. Beside the known OTase loci, STT3, OST1, WBP1, OST3, SWP1 and OST2, a novel locus, OST5, was identified. OST5 is an intron-containing gene encoding a putative membrane protein of 9.5 kDa present in highly purified OTase preparations. OST5 protein is not essential for growth but its depletion results in a reduced OTase activity. Suppression of an ost1 mutation by overexpression of OST5 indicates that this small membrane protein directly interacts with other OTase components, most likely with Ost1p. A strong genetic interaction with a stt3 mutation implies a role in complex assembly.

Molecular characterization of mitofilin (HMP), a mitochondria-associated protein with predicted coiled coil and intermembrane space targeting domains

We have identified and characterized a human protein of the mitochondria which we call mitofilin. Using monoclonal and polyclonal antibodies, we have isolated cDNA clones and characterized mitofilin biochemically. It appears as a 90 and 91 kDa doublet in western blots and is translated from a single 2.7 kb mRNA. Antibodies raised against cellular and bacterially-expressed protein given identical cytoplasmic immunofluorescence and immunoblot results. Mitofilin co-localizes with mitochondria in immunofluorescence experiments and co-purifies with mitochondria. Double label studies show co-localization only with mitochondria and not with Golgi or endoplasmic reticulum. Co-localization with mitochondria is retained when actin or tubulin are de-polymerized, and mitofilin is expressed in all human cell types tested. The cDNA encodes a polypeptide with a central alpha-helical region with predicted coiled coil domains flanked by globular amino and carboxy termini. Unlike coiled coil motor proteins, mitofilin is resistant to detergent extraction. The presence of mitochondrial targeting and stop-transfer sequences, along with the accessibility of mitofilin to limited proteolysis suggests that it resides predominantly in the intermembrane space, consistent with immuno-electron micrographs which show mitofilin mainly at the mitochondrial periphery. The cDNA sequence of mitofilin is identical to that recently reported by Icho et al. (1994; Gene 144, 301–306) for a mRNA preferentially expressed in heart muscle (HMP), consistent with the high levels of mitochondria in cardiac myocytes.