Diagnosis-related group refinement with diagnosis- and procedure-specific comorbidities and complications

Diagnosis-related groups have been revised through more refined uses of secondary diagnoses. Under the refined diagnosis-related groups, patients are distinguished with respect to classes of secondary diagnoses that are disease- and procedure-specific. Each class represents a different level of utilization for a given principal diagnosis or surgical procedure. The refined system was evaluated with national data from the Medicare program. Estimates of hospital costs and utilization based on refined diagnosis-related groups were more precise than those based on unrefined diagnosis-related groups. This approach to diagnosis-related group refinement does not represent a radical departure from the current diagnosis-related group framework and does not require new data collection efforts. Moreover, a payment system based on the refined model is less affected by the ordering of the diagnoses than under the existing diagnosis-related group system. How the refined diagnosis-related group framework can accommodate future refinements at all levels of the classification scheme is also discussed.

Rotational Raman scattering (Ring effect) in satellite backscatter ultraviolet measurements

A detailed radiative transfer calculation has been carried out to estimate the effects of rotational Raman scattering (RRS) on satellite measurements of backscattered ultraviolet radiation. Raman-scattered light is shifted in frequency from the incident light, which causes filling in of solar Fraunhofer lines in the observed backscattered spectrum (also known as the Ring effect). The magnitude of the rotational Raman scattering filling in is a function of wavelength, solar zenith angle, surface reflectance, surface pressure, and instrument spectral resolution. The filling in predicted by our model is found to be in agreement with observations from the Shuttle Solar Backscatter Ultraviolet Radiometer and the Nimbus-7 Solar Backscatter Ultraviolet Radiometer.

Assignment of hyperfine-shifted heme carbon resonances in ferricytochrome b5

The reverse detection heteronuclear multiple quantum coherence, HMQC, study of native bovine ferricytochrome b5 has provided the complete assignment of hyperfine shifted resonances of heme carbons attached proton(s). The dominant delocalized pi-spin density to vinyl groups gives rise to contact shifts which have opposite direction for a carbon and its attached proton(s). The most hyperfine shifted 13C heme signals are mainly generated from 3rd heme pyrrole ring substituents which identifies that the molecular orbital for facile electron transfer is oriented to exposed heme edge. Magnetic/electronic asymmetry of heme induced by two axial His makes spread the hyperfine shifted heme carbon resonances over the range of 280 ppm at 25 degrees C, which would be the more sensitive probe than those of proton resonances in characterizing the nature of heme electronic structure of ferricytochrome b5.

Activation of Bruton's tyrosine kinase (BTK) by a point mutation in its pleckstrin homology (PH) domain

Bruton's tyrosine kinase (BTK) is a nonreceptor tyrosine kinase critical for B cell development and function. Mutations in BTK result in X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (xid) in mice. Using a random mutagenesis scheme, we isolated a gain-of-function mutant called BTK* whose expression drives growth of NIH 3T3 cells in soft agar. BTK* results from a single point mutation in the pleckstrin homology (PH) domain, where a Glu is replaced by Lys at residue 41. BTK* shows an increase in phosphorylation on tyrosine residues and an increase in membrane targeting. Transforming activity requires kinase activity, a putative autophosphorylation site, and a functional PH domain. Mutation of the SH2 or SH3 domains did not affect the activity of BTK*. Expression of BTK* could also relieve IL-5 dependence of a B lineage cell line. These results show that transformation activation and regulation of BTK are critically dependent on the PH domain.

Investigation of vibration characteristics of the ligamentous lumbar spine using the finite element approach

A nonlinear, three-dimensional finite element model of the ligamentous L4-S1 segment was developed to analyze the dynamic response of the spine in the absence of damping. The effects of the upper body mass were simulated by including a mass of 40 kg on the L4 vertebral body. The modal analyses of the model indicated a resonant frequency of 17.5 Hz in axial mode and 3.8 Hz in flexion-extension mode. Accordingly, the predicted responses for the cyclic load of -400 +/- 40 N applied at four different frequencies (5, 11, 16.5, and 25 Hz) were compared with the corresponding results for axial compressive static loads (-360, and -440 N). As compared to the static load cases, the predicted responses were higher for the cyclic loading. For example, the effect of cyclic load at 11 Hz was to produce significant changes (9.7-19.0 percent) in stresses, loads transmitted through the facets, intradiscal pressure (IDP), disk bulge, as compared to the static load predictions. The responses were found to be frequency dependent as well; supporting the in vivo observations of other investigators that the human spine has a resonant frequency. For example, the 11 Hz model (DYN11) compared to the DYN5 model showed an increase in majority of the predicted parameters. The parameters showed an increase with frequency until 17.5 Hz (resonant frequency of the model); thereafter a decrease at 25 Hz.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis of a photoaffinity taxol analogue and its use in labeling tubulin

A photoaffinity analogue of taxol, N-([3,5-3H]-4-azidobenzoyl)-N-debenzoyltaxol (7), was synthesized and used to photolabel microtubules. Approximately 20% of the noncovalently bound analogue becomes covalently bound upon irradiation at 300 nm. Incorporated label was stable to a 50% ethanol solution and sodium dodecyl sulfate. About 80% of the incorporated label was found in the beta-subunit and 20% in the alpha-subunit. Incorporation did not occur into unpolymerized tubulin, consistent with the fact that taxol binds only to polymerized tubulin, and was decreased by the presence of taxol. Little or no nonspecific labeling occurs. This analogue is currently being used to identify taxol binding site(s) on tubulin.

TAR RNA-binding protein is an inhibitor of the interferon-induced protein kinase PKR

A cDNA encoding a double-stranded-RNA (dsRNA)-binding protein was isolated by screening a HeLa cell cDNA expression library for proteins that bind the HIV-1 Rev-responsive-element RNA. The cDNA encoded a protein that was identical to TRBP, the previously reported cellular protein that binds the transactivation response element (TAR) RNA of human immunodeficiency virus type 1. TRBP inhibited phosphorylation of the interferon-induced ribosome-associated protein kinase PKR and of the eukaryotic translation initiation factor eIF-2 alpha in a transient-expression system in which the translation of a reporter gene was inhibited by the localized activation of PKR. TRBP expression in HeLa cells complemented the growth and protein-synthesis defect of a vaccinia virus mutant lacking the expression of the dsRNA-binding protein E3L. These results implicate TRBP as a cellular regulatory protein that binds RNAs containing specific secondary structure(s) to mediate the inhibition of PKR activation and stimulate translation in a localized manner.

Ocular and optic nerve hemorrhages in abused infants with intracranial injuries

PURPOSE

To ascertain whether the pathology of the eye and optic nerve might be useful in determining the manner of death in infants who died after sustaining apparent nonaccidental intracranial injury.

METHODS

Complete autopsies were performed on 13 infants who died of acute intracranial injuries after nonaccidental trauma. The infants were divided into two groups: nine with physical evidence of blunt trauma to the head, and four without detectable scalp or skull injury whose intracranial injuries were attributed to violent shaking (shaken baby syndrome). Six infants with no intracranial injuries who died suddenly from unidentifiable causes (the so-called sudden infant death syndrome) served as controls.

RESULTS

Optic nerve sheath hemorrhage, most prominent in the subdural space, was present in all 13 infants with nonaccidental intracranial injury. Multilayered retinal hemorrhage was present in at least one eye of 11 of these 13 infants. The location and quantity of the intraocular and optic nerve sheath hemorrhages did not differ in those with external head trauma and those without scalp or skull lesions. A single control infant had a few erythrocytes in the nerve fiber layer of the anterior optic nerve of one eye. The remainder of the control infants did not have evidence of hemorrhage in the eye or optic nerve sheath.

CONCLUSION

Histopathologic analysis of optic nerve sheath and intraocular hemorrhages may be helpful in distinguishing traumatic from non-traumatic causes of death in infants.

Characterization of the gene encoding the human transcriptional elongation factor TFIIS

The transcriptional elongation factor TFIIS causes stimulation of RNA polymerase II elongation and readthrough of some of the elongation blocks. We present cloning and sequence characterization of the human TFIIS gene and a pseudogene. The intron-less organization of both of these genes indicates that previously identified cDNAs which suggested the presence of an intron were the products of cloning artifacts. The gene is organized in an uninterrupted ORF which codes for 301 amino acids, whereas the pseudogene lacks an ORF able to code for a full-length protein. The potential promoter for the gene has two putative GC-box-type consensus sequences, two CCAAT-box consensus sequences, and is bounded by a human Alu sequence. Two potential transcriptional termination signal sequences downstream from the consensus polyadenylation signal are proposed.

Human monoclonal antibody SK1-mediated cytotoxicity against colon cancer cells

PURPOSE

Human monoclonal antibody (HuMAb) SK1, a human monoclonal IgM, has previously been shown to react selectively with a wide range of human carcinomas. In this study, the complement-dependent cytotoxicity (CDC) mediated by the HuMAb SK1 was investigated.

METHODS

The presence of AgSK1 on the two studied cell lines, HT29 and PANC-1, was evaluated by the immunocytochemical staining. The intracellular and surface locations of the targeting antigen of HuMAb SK1 were further characterized by the study of flow cytometry. The specific lysis of target cells by the HuMAb SK1 in the CDC assay was studied.

RESULTS

In the presence of human complement, the HuMAb SK1 was shown to be effective in the lysis of cultured human gastrointestinal cancer cells as well as the fresh colon cancer cells derived from the patient's specimens. In addition, our data suggested that HuMAb SK1 activated the mouse complement in a similar magnitude.

CONCLUSIONS

We concluded that HuMAb SK1 showed some promise for future clinical trials. The in vitro CDC effect of HuMAb SK1 with mouse complement suggested that the antitumor effect of HuMAb SK1 might be successfully studied in the nude mouse model bearing xenografts of human colon cancer as a part of the preclinical evaluation.

Fission yeast with DNA polymerase delta temperature-sensitive alleles exhibits cell division cycle phenotype

DNA polymerases alpha and delta are essential enzymes believed to play critical roles in initiation and replication of chromosome DNA. In this study, we show that the genes for Schizosaccharomyces pombe (S.pombe) DNA polymerase alpha and delta (pol alpha+ and pol delta+) are essential for cell viability. Disruption of either the pol alpha+ or pol delta+ gene results in distinct terminal phenotypes. The S.pombe pol delta+ gene is able to complement the thermosensitive cdc2-2 allele of Saccharomyces cerevisiae (S.cerevisiae) at the restrictive temperature. By random mutagenesis in vitro, we generated three pol delta conditional lethal alleles. We replaced the wild type chromosomal copy of pol delta+ gene with the mutagenized sequence and characterized the thermosensitive alleles in vivo. All three thermosensitive mutants exhibit a typical cell division cycle (cdc) terminal phenotype similar to that of the disrupted pol delta+ gene. Flow cytometric analysis showed that at the nonpermissive temperature all three mutants were arrested in S phase of the cell cycle. The three S.pombe conditional pol delta alleles were recovered and sequenced. The mutations causing the thermosensitive phenotype are missense mutations. The altered amino acid residues are uniquely conserved among the known polymerase delta sequences.

Ligand binding induces an asymmetrical transmembrane signal through a receptor dimer

Two ligand (aspartate)-binding pockets are formed at the interface between the subunits of the Tar homodimer, a bacterial chemoreceptor. Using mutant heterodimers of a hybrid receptor, Taz1, which consists of the external domain of Tar and the cytoplasmic domain of EnvZ, we disrupted either one or the other of the two ligand-binding pockets. We found that occupation of only one of the ligand-binding pockets was sufficient for induction of a transmembrane signal, and that the subunit responsible for the binding of the amino group of the ligand transduces the signal.

Post-translational processing and Thr-206 are required for glycosylasparaginase activity

Lysosomal glycosylasparaginase is encoded as a 36.5 kDa polypeptide that is post-translationally processed to subunits of 19.5 kDa (heavy) and 15 kDa (light). Recombinant glycosylasparaginase has been expressed in Spodoptera frugiperda insect cells enabling the precursor and processed forms to be isolated and their catalytic potential determined. Only the subunit conformation was functional indicating glycosylasparaginase is encoded as an inactive zymogen. The newly created amino terminal residue of the light subunit following maturation, Thr-206, is believed to be involved in the catalytic mechanism [1992, J. Biol. Chem. 267, 6855-6858]. Here we have constructed two amino acid substitution mutants replacing Thr-206 with Ala-206 or Ser-206 and demonstrate that both destroy enzyme activity.