Reduced dimension discrete variable representation study of cis-trans isomerization in the S1 state of C2H2.

Isomerization between the cis and trans conformers of the S(1) state of acetylene is studied using a reduced dimension discrete variable representation (DVR) calculation. Existing DVR techniques are combined with a high accuracy potential energy surface and a kinetic energy operator derived from FG theory to yield an effective but simple Hamiltonian for treating large amplitude motions. The spectroscopic signatures of the S(1) isomerization are discussed, with emphasis on the vibrational aspects. The presence of a low barrier to isomerization causes distortion of the trans vibrational level structure and the appearance of nominally electronically forbidden à (1)A(2)←X̃ (1)Σ(g)(+) transitions to vibrational levels of the cis conformer. Both of these effects are modeled in agreement with experimental results, and the underlying mechanisms of tunneling and state mixing are elucidated by use of the calculated vibrational wavefunctions.

TIA-1 is a translational silencer that selectively regulates the expression of TNF-alpha.

TIA-1 and TIAR are related proteins that bind to an AU-rich element (ARE) in the 3' untranslated region of tumor necrosis factor alpha (TNF-alpha) transcripts. To determine the functional significance of this interaction, we used homologous recombination to produce mutant mice lacking TIA-1. Although lipopolysaccharide (LPS)-stimulated macrophages derived from wild-type and TIA-1(-/-) mice express similar amounts of TNF-alpha transcripts, macrophages lacking TIA-1 produce significantly more TNF-alpha protein than wild-type controls. The half-life of TNF-alpha transcripts is similar in wild-type and TIA-1(-/-) macrophages, indicating that TIA-1 does not regulate transcript stability. Rather, the absence of TIA-1 significantly increases the proportion of TNF-alpha transcripts that associate with polysomes, suggesting that TIA-1 normally functions as a translational silencer. TIA-1 does not appear to regulate the production of interleukin 1 beta, granulocyte-macrophage colony-stimulating factor or interferon gamma, indicating that its effects are, at least partially, transcript specific. Mice lacking TIA-1 are hypersensitive to the toxic effects of LPS, indicating that this translational control pathway may regulate the organismal response to microbial stress.

Cyclin E2: a novel CDK2 partner in the late G1 and S phases of the mammalian cell cycle.

We report here the cloning and characterization of human and mouse cyclin E2, which define a new subfamily within the vertebrate E-type cyclins, while all previously identified family-members belong to the cyclin El subfamily. Cyclin E2/CKD2 and cyclin E/CDK2 complexes phosphorylate histone H1 in vitro with similar specific activities and both are inhibited by p27Kip1. Cyclin E2 mRNA levels in human cells oscillate throughout the cell cycle and peak at the G1/S boundary, in parallel with the cyclin E mRNA. In cells, cyclin E2 is complexed with CDK2, p27 and p21. Like cyclin E, cyclin E2 is an unstable protein in vivo and is stabilized by proteasome inhibitors. Cyclin E2-associated kinase activity rises in late G1 and peaks very close to cyclin E activity. In two malignantly transformed cell lines, cyclin E2 activity is sustained throughout S phase, while cyclin E activity has already declined and cyclin A activity is only beginning to rise. We speculate that cyclin E2 is not simply redundant with cyclin E, but may regulate distinct rate-limiting pathway(s) in G1-S control.

RNA-binding protein TIAR is essential for primordial germ cell development.

Primordial germ cells (PGCs) give rise to both eggs and sperm via complex maturational processes that require both cell migration and proliferation. However, little is known about the genes controlling gamete formation during the early stages of PGC development. Although several mutations are known to severely reduce the number of PGCs reaching and populating the genital ridges, the molecular identity of only two of these genes is known: the c-kit receptor protein tyrosine kinase and the c-kit ligand (the steel factor). Herein, we report that mutant mice lacking TIAR, an RNA recognition motif/ribonucleoprotein-type RNA-binding protein highly expressed in PGCs, fail to develop spermatogonia or oogonia. This developmental defect is a consequence of reduced survival of PGCs that migrate to the genital ridge around embryonic day 11.5 (E11.5). The numbers of PGCs populating the genital ridge in TIAR-deficient embryos are severely reduced compared to wild-type embryos by E11.5 and in the mutants PGCs are completely absent at E13.5. Furthermore, TIAR-deficient embryonic stem cells do not proliferate in the absence of exogenous leukemia inhibitory factor in an in vitro methylcellulose culture assay, supporting a role for TIAR in regulating cell proliferation. Because the development of PGCs relies on the action of several growth factors, these results are consistent with a role for TIAR in the expression of a survival factor or survival factor receptor that is essential for PGC development. TIAR-deficient mice thus provide a model system to study molecular mechanisms of PGC development and possibly the basis for some forms of idiopathic infertility.

Involvement of p130(Cas) and p105(HEF1), a novel Cas-like docking protein, in a cytoskeleton-dependent signaling pathway initiated by ligation of integrin or antigen receptor on human B cells.

The Crk-associated substrate p130(Cas) (Cas) and the recently described human enhancer of filamentation 1 (HEF1) are two proteins with similar structure (64% amino acid homology), which are thought to act as "docking" molecules in intracellular signaling cascades. Both proteins contain an N-terminal Src homology (SH), three domain and a cluster of SH2 binding motifs. Here we show that ligation of either beta1 integrin or B cell antigen receptor (BCR) on human tonsillar B cells and B cell lines promoted tyrosine phosphorylation of HEF1. In contrast, Cas tyrosine phosphorylation was observed in certain B cell lines but not in tonsillar B cells, indicating a more general role for HEF1 in B cell signaling. Interestingly, pretreatment of tonsillar B cells with cytochalasin B dramatically reduced both integrin- and BCR-induced HEF1 phosphorylation, suggesting that some component of the BCR-mediated signaling pathway is closely linked with a cytoskeletal reorganization. Both HEF1 and Cas were found to complex with the related adhesion focal tyrosine kinase (RAFTK), and when tyrosine phosphorylated, with the adapter molecule CrkL. In addition, the two molecules were detected in p53/56(Lyn) immunoprecipitates, and Lyn kinase was found to specifically bind the C-terminal proline-rich sequence of Cas in an in vitro binding assay. These associations implicate HEF1 and Cas as important components in a cytoskeleton-linked signaling pathway initiated by ligation of beta1 integrin or BCR on human B cells.

Structure, tissue distribution and genomic organization of the murine RRM-type RNA binding proteins TIA-1 and TIAR.

TIA-1 and TIAR are RNA binding proteins of the RNA recognition motif (RRM)/ribonucleoprotein (RNP) family that have been implicated as effectors of apoptotic cell death. We report the structures of murine TIA-1 and TIAR (mTIA-1 and mTIAR) deduced from cDNA cloning, the mRNA and protein tissue distribution of mTIA-1 and mTIAR, and the exon-intron structures of the mTIA-1 and mTIAR genes. Both mTIA-1 and mTIAR are comprised of three approximately 100 amino acid N-terminal RRM domains and a approximately 90 amino acid C-terminal auxiliary domain. This subfamily of RRM proteins is evolutionarily well conserved; mTIA-1 and mTIAR are 80% similar to each other, and 96 and 99% similar to hTIA-1 and hTIAR, respectively. The overall exon-intron structures of the mTIA-1 and mTIAR genes are also similar to each other, as well as to the human TIA-1 gene structure. While Northern blot analysis reveals that mTIA-1 and mTIAR mRNAs have a broad tissue distribution, mTIA-1 and mTIAR proteins are predominantly expressed in brain, testis and spleen. At least two isoforms of both mTIA-1 and mTIAR are generated by alternative splicing. Murine TIA-1 isoforms including or lacking the exon 5 encoded sequences are expressed at a ratio of approximately 1:1, whereas mTIAR isoforms including or lacking the 5'-end of exon 3 sequences are expressed in a approximately 1:6 ratio. Molecular characterization of murine TIA-1 and TIAR RNA binding proteins provides the basis for a genetic analysis of the functional roles of these proteins during mammalian development.

Facilitated communicators' performance on a task of receptive language.

Most controlled studies of facilitated communication (FC) have not validated it. One task, however, on which positive effects of FC have been demonstrated without facilitator influence is the Peabody Picture Vocabulary Test-R (PPVT-R). The present study investigated if the use of FC could be validated for either a group of subjects with autism or a group with severe to profound cognitive impairments, on the PPVT-R when facilitators were effectively screened from all visual and auditory stimuli. Additionally, the effect of mode of input-auditory or visual-on subjects' performance was investigated. Results did not validate the use of FC for the administration of the PPVT-R nor did they show any notable advantage of one mode of input over another.

The risk of perforation when children with possible appendicitis are observed in the hospital.

The morbidity rate from perforation demands that appendicitis be diagnosed promptly in children with abdominal pain. Although admitting and observing uncertain instances of appendicitis can refine the diagnostic accuracy, it is often claimed, but not proved, that this necessitates increasing the number of perforations. To assess the risk of perforation while observing uncertain instances of childhood appendicitis, we admitted 150 consecutive referrals during a period of one and one-half years. Immediate appendectomy was performed for 74 patients (49 percent) with convincing clinical signs and symptoms for appendicitis. The remaining 76 (51 percent) with unconvincing clinical signs and symptoms were observed as inpatients. One-third of the patients admitted for observation (26 of 76) underwent appendectomy after an average period of 12 hours. Two-thirds (50 of 76) of the patients got better and were discharged from the hospital without an appendectomy after an average admission of two days. Seven of the 100 appendices removed were normal. Three of the observed patients had perforations, one of whom may have perforated during observation, but that child went on to do well. The 50 patients who got well without appendectomy were similar to the patients with appendicitis, but significantly less likely to have peritoneal signs (8 versus 70 percent), tenderness in the right lower quadrant (48 versus 81 percent) and guarding (19 versus 75 percent). We conclude that admission and active observation in the hospital of children with possible, but unconvincing, signs and symptoms of appendicitis is a safe and effective way to determine which patients need an operation.

Colorectal carcinoma in the young. A case report and review of the literature.

A case of sigmoid carcinoma in a 16-year-old boy is presented and the topic of colonic carcinoma in the young is reviewed. Although colon carcinoma in the younger patient is uncommon, its prognosis is distinctly worse than in the adult population, because the preponderance of mucinous adenocarcinoma in children and young adults represents a more virulent type of colonic malignancy and because the delay in diagnosis contributes to a more advanced stage of the disease at the time of presentation. When dealing with symptoms potentially referrable to this disease, a thorough diagnostic work-up should ensue.

Infantile hemangioendothelioma of heterotopic intrathoracic liver associated with diaphragmatic hernia.

An autopsy of a six-hour-old term neonate, who died during surgery for repair of a left diaphragmatic hernia, revealed an infantile hemangioendothelioma type I arising in a heterotopic lobe of liver in the left thorax. The upper pole of the tumor was attached by fibrovascular tissue to the lower lobe of the left hypoplastic lung. A pedicle attached to the lower pole of the heterotopic liver pierced through the diaphragm to the left lobe of the normal liver. This case is an example of an unusual association of congenital malformation and putative neoplasm.

Familial polyposis coli. Results of mucosal proctectomy with ileoanal anastomosis.

The outcome of mucosal proctectomy with ileoanal anastomosis in patients with polyposis coli has not been well studied. A series of 25 patients with polyposis treated at the Mount Sinai Hospital over a period of ten years is reported. The mean age of the patients was 23 years. Early postoperative complications were present in seven patients and consisted of thrombophlebitis (three), pelvic sepsis (three), and retraction of the anastomosis (one). Intestinal obstruction requiring laparotomy occurred in another five patients. Twenty-three patients were followed for a mean of 47 months after closure of the ileostomy. Ninety-one percent are satisfied with the operative results. The mean number of bowel movements per 24 hours is 6.0. All patients are continent, but eight have occasional episodes of rectal seepage at night. Nearly 50 percent require some antidiarrheal medication. New adenomatous polyps have developed just above the dentate line in four patients. Patients with polyposis coli seem to have fewer serious complications requiring excision of the ileoanal anastomosis than patients with ulcerative colitis. They also should have lifelong surveillance of the entire gastrointestinal tract even after total colectomy with ileoanal anastomosis.

Colonic obstruction in a child with von Recklinghausen's neurofibromatosis.

A child is reported who developed partial colonic obstruction from an intussuscepting polypoid mass in the transverse colon. A 5 cm plexiform ganglioneurofibroma was found at laparotomy. Examination of the entire gastrointestinal tract revealed no other neurogenic tumors. Gastrointestinal involvement by neurofibromatosis in children is rare; however, children with von Recklinghausen's disease who complain of vague abdominal symptoms should be evaluated for gastrointestinal tumors.

Mesenteric and retroperitoneal cysts.

Mesenteric and retroperitoneal cysts are rare intra-abdominal tumors. Ten new patients are presented as well as 152 other cases reported in the English literature. These 162 cases were then analyzed for significant trends. Patients under 10 years of age were significantly different from the older group with respect to a shorter duration of symptoms, a higher number of patients requiring an emergency operation, a lower number of recurrences and the location of the cyst. Patients with retroperitoneal cysts were more likely to have incomplete excision of the cyst and therefore had a higher incidence of recurrence. They also required marsupialization more often. Retroperitoneal cysts should be considered a different entity from mesenteric cysts even though they present clinically in a similar fashion. The outcome of surgical treatment is less satisfactory in patients with retroperitoneal cysts.

Patterns of treatment of gallstone ileus over a 45-year period.

All patients with gallstone ileus admitted to our institutions between 1938 and 1982 were retrospectively analyzed by grouping the patients into 10-year periods. Forty-five patients were studied, of whom 39 required operation. When hospital statistics for admissions, length of stay, and mortality rates from the Mount Sinai Hospital were compared to the gallstone ileus data, it was found that there has been no significant change in the admission rate for these patients. The mortality rate and length of stay of gallstone ileus patients has also remained constant over the past 25 years despite the general hospital decrease in both of these numbers. There has been no change in the complication rate, duration of symptoms prior to admission, or the preoperative diagnostic rate of gallstone ileus during the duration of this study.

The processing of the sounds and meanings of ongoing speech by aphasic subjects.

The ability of aphasic subjects to process the sounds and meanings of ongoing speech was tested. Subjects, 10 aphasic and 20 control, heard test sentences which contained one member of phonemically similar word pairs in one of three semantic contexts: congruent, neutral, and noncongruent. Immediately after hearing a sentence, subjects were to indicate which member of the word pair had been in the sentence. All subject groups had similar overall patterns of response to the different semantic contexts. The division of aphasic subjects into groups of high and low comprehenders revealed response differences. High comprehending aphasic subjects, like control subjects, demonstrated interactive processing of the sounds and meaning of speech while low comprehending aphasic subjects did not.

Mucosal proctectomy without reservoir.

Mucosal proctectomy with endorectal pull-through allows the removal of all colonic mucosa with preservation of continence. This operation was performed in 19 patients with familial polyposis coli and ulcerative colitis. A temporary loop ileostomy was used to defunctionalize the anastomosis. Intestinal continuity was restored in 17 of the 19 patients. Mean duration of follow-up was 29 months. All patients are continent, and the mean number of bowel movements per 24 hours is 6. Follow-up barium studies revealed a gradual dilatation of the terminal ileum within the rectal cuff which accounts for the decrease in the number of bowel movements. This operation eliminates the risk of carcinoma without compromising sphincter function.

Cervical thymic cysts in children.

Thymic cysts are a rare cause of cervical masses in children. The cysts usually appear between ages 6 and 7 years and present as a soft swelling in the anterior triangle of the neck. The cysts may be small and unilocular or large and multilocular; they produce few symptoms. The etiology is unclear but may be related to remnants of tissue left in the cervical region when the thymus gland descends from the neck to the mediastinum during embryologic development. Forty-three cases of cervical thymic cysts have been reported in patients under 20 years of age. Two additional cases are reported in boys 5 and 9 years of age.