Comparative Mutagenesis Studies of Retinal Release in Light-Activated Zebrafish Rhodopsin Using Fluorescence Spectroscopy.

Rhodopsin is the visual pigment responsible for initiating scotopic (dim-light) vision in vetebrates. Once activated by light, release of all-trans-retinal from rhodopsin involves hydrolysis of the Schiff base linkage, followed by dissociation of retinal from the protein moiety. This kinetic process has been well studied in model systems such as bovine rhodopsin, but not in rhodopsins from cold-blooded animals, where physiological temperatures can vary considerably. Here, we characterize the rate of retinal release from light-activated rhodopsin in an ectotherm, zebrafish (Danio rerio), demonstrating in a fluorescence assay that this process occurs more than twice as fast as bovine rhodopsin at similar temperatures in 0.1% dodecyl maltoside. Using site-directed mutagenesis, we found that differences in retinal release rates can be attributed to a series of variable residues lining the retinal channel in three key structural motifs: an opening in metarhodopsin II between transmembrane helix 5 (TM5) and TM6, in TM3 near E122, and in the "retinal plug" formed by extracellular loop 2 (EL2). The majority of these sites are more proximal to the ß-ionone ring of retinal than the Schiff base, indicating their influence on retinal release is more likely due to steric effects during retinal dissociation, rather than alterations to Schiff base stability. An Arrhenius plot of zebrafish rhodopsin was consistent with this model, inferring that the activation energy for Schiff base hydrolysis is similar to that of bovine rhodopsin. Functional variation at key sites identified in this study is consistent with the idea that retinal release might be an adaptive property of rhodopsin in vertebrates. Our study is one of the few investigating a nonmammalian rhodopsin, which will help establish a better understanding of the molecular mechanisms contributing to vision in cold-blooded vertebrates.

Enhanced production of direct photons in Au + Au collisions at square root(S(NN)) = 200 GeV and implications for the initial temperature.

The production of e+ e- pairs for m(e+ e-)<0.3 GeV/c2 and 1

Transition in yield and azimuthal shape modification in dihadron correlations in relativistic heavy ion collisions.

Hard-scattered parton probes produced in collisions of large nuclei indicate large partonic energy loss, possibly with collective produced-medium response to the lost energy. We present measurements of π^{0} trigger particles at transverse momenta p{T}{t}=4-12 GeV/c and associated charged hadrons (p{T}{a}=0.5-7 GeV/c) vs relative azimuthal angle Δϕ in Au+Au and p+p collisions at sqrt[s{NN}]=200 GeV. The Au+Au distribution at low p{T}{a}, whose shape has been interpreted as a medium effect, is modified for p{T}{t}<7 GeV/c. At higher p{T}{t}, the data are consistent with unmodified or very weakly modified shapes, even for the lowest measured p{T}{a}, which quantitatively challenges some medium response models. The associated yield of hadrons opposing the trigger particle in Au+Au relative to p+p (I{AA}) is suppressed at high p{T} (I{AA}≈0.35-0.5), but less than for inclusive suppression (R{AA}≈0.2).

Structure of Bcl-xL-Bak peptide complex: recognition between regulators of apoptosis.

Heterodimerization between members of the Bcl-2 family of proteins is a key event in the regulation of programmed cell death. The molecular basis for heterodimer formation was investigated by determination of the solution structure of a complex between the survival protein Bcl-xL and the death-promoting region of the Bcl-2-related protein Bak. The structure and binding affinities of mutant Bak peptides indicate that the Bak peptide adopts an amphipathic alpha helix that interacts with Bcl-xL through hydrophobic and electrostatic interactions. Mutations in full-length Bak that disrupt either type of interaction inhibit the ability of Bak to heterodimerize with Bcl-xL.

Endocrine and reproductive differences and genetic divergence in two populations of the cockroach Diploptera punctata.

The viviparous cockroach, Diploptera punctata, has been a valuable model organism for studies of the regulation of reproduction by juvenile hormone (JH) in insects. As a result of its truly viviparous mode of reproduction, precise regulation of JH biosynthesis and reproduction is required for production of offspring, providing a model system for the study of the relationship between JH production and oocyte growth and maturation. Most studies to date have focused on individuals isolated from a Hawaiian population of this species. A new population of this cockroach was found in Nakorn Pathom, Thailand, which demonstrated striking differences in cuticle pigmentation and mating behaviours, suggesting possible physiological differences between the two populations. To better characterize these differences, rates of JH release and oocyte growth were measured during the first gonadotrophic cycle. The Thai population was found to show significantly earlier increases in the rate of JH release, and oocyte development as compared with the Hawaiian population. Breeding experiments to determine the degree of interfertility between the two populations demonstrated greatly reduced fertility in crosses between the two populations. Additionally, levels of genetic divergence between the two populations estimated by sequencing a fragment of the mitochondrial 16S rRNA gene were surprisingly high. The significant differences in physiology and mating behaviours, combined with the reduced interfertility and high levels of sequence divergence, suggest that these two populations of D. punctata are quite distinct, and may even be in the process of speciation. Moreover, these studies have important implications for the study of JH function in the reproductive cycle of insects, as differences in timing of rates of JH biosynthesis may suggest a process of heterochrony in reproduction between the two populations.

The BH3 domain of Bcl-x(S) is required for inhibition of the antiapoptotic function of Bcl-x(L).

bcl-x is a member of the bcl-2 family of genes. The major protein product, Bcl-x(L), is a 233-amino-acid protein which has antiapoptotic properties. In contrast, one of the alternatively spliced transcripts of the bcl-x gene codes for the protein Bcl-x(S), which lacks 63 amino acids present in Bcl-x(L) and has proapoptotic activity. Unlike other proapoptotic Bcl-2 family members, such as Bax and Bak, Bcl-x(S) does not seem to induce cell death in the absence of an additional death signal. However, Bcl-x(S) does interfere with the ability of Bcl-x(L) to antagonize Bax-induced death in transiently transfected 293 cells. Mutational analysis of Bcl-x(S) was conducted to identify the domains necessary to mediate its proapoptotic phenotype. Deletion mutants of Bcl-x(S) which still contained an intact BH3 domain retained the ability to inhibit survival through antagonism of Bcl-x(L). Bcl-x(S) was able to form heterodimers with Bcl-x(L) in mammalian cells, and its ability to inhibit survival correlated with the ability to heterodimerize with Bcl-x(L). Deletion mutants of Bax and Bcl-2, which lacked BH1 and BH2 domains but contained a BH3 domain, were able to antagonize the survival effect conferred by Bcl-x(L). The results suggest that BH3 domains from both pro- and antiapoptotic Bcl-2 family members, while lacking an intrinsic ability to promote programmed cell death, can be potent inhibitors of Bcl-x(L) survival function.

Bad is a BH3 domain-containing protein that forms an inactivating dimer with Bcl-XL.

The Bcl-2 related protein Bad is a promoter of apoptosis and has been shown to dimerize with the anti-apoptotic proteins Bcl-2 and Bcl-XL. Overexpression of Bad in murine FL5.12 cells demonstrated that the protein not only could abrogate the protective capacity of coexpressed Bcl-XL but could accelerate the apoptotic response to a death signal when it was expressed in the absence of exogenous Bcl-XL. Using deletion analysis, we have identified the minimal domain in the murine Bad protein that can dimerize with Bcl-xL. A 26-amino-acid peptide within this domain, which showed significant homology to the alpha-helical BH3 domains of related apoptotic proteins like Bak and Bax, was found to be necessary and sufficient to bind Bcl-xL. To determine the role of dimerization in regulating the death-promoting activity of Bad and the death-inhibiting activity of Bcl-xL, mutations within the hydrophobic BH3-binding pocket in Bcl-xL that eliminated the ability of Bcl-xL to form a heterodimer with Bad were tested for the ability to promote cell survival in the presence of Bad. Several of these mutants retained the ability to impart protection against cell death regardless of the level of coexpressed Bad protein. These results suggest that BH3-containing proteins like Bad promote cell death by binding to antiapoptotic members of the Bcl-2 family and thus inhibiting their survival promoting functions.

"Loop" domain is necessary for taxol-induced mobility shift and phosphorylation of Bcl-2 as well as for inhibiting taxol-induced cytosolic accumulation of cytochrome c and apoptosis.

Taxol, 1-beta-D-arabinofuranosylcytosine (ara-C), and etoposide induce apoptosis in HL-60 cells that is blocked by overexpression of Bcl-2 or Bcl-xL.A 60-amino acid "loop" domain of Bcl-2 and Bcl-xL that contains phosphorylation sites is known to negatively regulate their antiapoptotic function. In the present studies, Taxol-, ara-C-, or etoposide-induced apoptosis was examined in HL-60/Bcl-2delta and HL-60/Bcl-xLdelta cells that express the loop-deletional mutant cDNA constructs p19Bcl-2delta32-80 and p18Bcl-xLdelta26-83, respectively. This was compared with control HL-60/neo cells as well as HL-60/Bcl-2 and HL-60/Bcl-xL cells. The latter two cell lines overexpress full-length Bcl-2 and Bcl-xL, respectively. Immunoblot analyses showed that HL-60/neo and HL-60/Bcl-2delta cells express similar levels of p26Bcl-2. In contrast, as compared with HL-60/neo, HL-60/Bcl-xLdelta cells expressed significantly lower levels of p26Bcl-2. p29Bcl-xL and p21Bax levels were similar in all cell types. Exposure to etoposide (50 microM) or ara-C (100 microM) for 4 h induced apoptosis in HL-60/neo cells, but not in HL-60/Bcl-2, HL-60/Bcl-xL, HL-60/Bcl-2delta, or HL-60/Bcl-xLdelta cells. In contrast, Taxol treatment (500 nM for 24 h) triggered the molecular cascade of apoptosis, represented by the cytosolic increase of cytochrome c and poly(ADP-ribose) polymerase or the DNA fragmentation factor cleavage activity of caspase-3 in HL-60/neo cells as well as in HL-60/Bcl-xLdelta and HL-60/Bcl-2delta cells, but not in their counterparts overexpressing full-length Bcl-2 and Bcl-xL. Equal amounts of p26Bcl-2 were coimmunoprecipitated with apoptosis protease-activating factor 1 (APAF-1) in HL-60/neo and HL-60/Bcl-2delta cells, whereas a markedly higher level of p26Bcl-2 coimmunoprecipitated with APAF-1 in HL-60/Bcl-2 cells. In association with Taxol-induced apoptosis, the levels of Bcl-2 that were coimmunoprecipitated with APAF-1 declined in HL-60/neo and HL-60/Bcl-2delta cells. This was not observed in HL-60/Bcl-2 cells, in which Taxol-induced apoptosis was blocked. Previous studies have demonstrated that Taxol induces phosphorylation of Bcl-2 in association with Taxol-induced apoptosis of HL-60/neo cells. Immunoblot analysis demonstrated a Taxol-induced mobility shift of Bcl-2 but not p19Bcl-2delta. Taxol also increased [32P]Pi incorporation in p26Bcl-2, but not in p19Bcl-2delta or p18Bcl-xL. These findings indicate that the loop domain is necessary for the Taxol-induced mobility shift and phosphorylation of Bcl-2. Loop domain also seems to be necessary for the antiapoptotic effect of Bcl-2 against Taxol-induced apoptosis but not ara-C- or etoposide-induced apoptosis.

Bone tissue responses to Mg-incorporated oxidized implants and machine-turned implantsin the rabbit femur.

Previous studies have demonstrated a significant improvement in the bone response to oxidized titanium implants. Little is known about the effects of specific oxide properties on the bone tissue responses to titanium implants. This study in-vestigated the bone tissue responses to magnesium (Mg)-incorporated oxidized titanium implants and machine-turned titani-um implants in the rabbit femur. The oxidized implants were prepared using micro arc oxidation (MAO) methods. Surface oxide properties were characterized by using various surface analytic techniques, involving scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and optical interferometry. Screw shaped titanium implants, 10 machine-turned implants (controls) and 10 Mg-incorporated im-plants (tests) were inserted in the femoral condyles of 10 New Zealand white rabbits. After a 6-week healing period, resonance frequency analyses and removal torque measurements of the Mg-incorporated oxidized implants demonstrated significant im-provements in implant integration with bone in comparison to machine-turned implants, p=0.007 and p=0.017, respectively. Bone growth in the pores of the oxidized implants was probably incomplete at a follow-up of 6 weeks, as indicated by SEM and EDS measurements. Mg-incorporated titanium implants significantly improved bone responses as compared with machine-turned control implants. Considering the differences and similarities of the surface oxide properties of controls and test im-plants, the enhanced bone responses to Mg-incorporated implants could be explained by the Mg surface chemistry of the test im-plants. (Journal of Applied Biomaterials and Biomechanics 2005; 3: 18-28).

The influence of catastrophising on treatment outcomes after surgery for lumbar spinal stenosis.

Pain catastrophising is an adverse coping mechanism, involving an exaggerated response to anticipated or actual pain. The purpose of this study was to investigate the influence of pain 'catastrophising', as measured using the pain catastrophising scale (PCS), on treatment outcomes after surgery for lumbar spinal stenosis (LSS). A total of 138 patients (47 men and 91 women, mean age 65.9; 45 to 78) were assigned to low (PCS score < 25, n = 68) and high (PCS score ≥ 25, n = 70) PCS groups. The primary outcome measure was the Oswestry Disability Index (ODI) 12 months after surgery. Secondary outcome measures included the ODI and visual analogue scale (VAS) for back and leg pain, which were recorded at each assessment conducted during the 12-month follow-up period The overall changes in the ODI and VAS for back and leg pain over a 12-month period were significantly different between the groups (ODI, p < 0.001; VAS for back pain, p < 0.001; VAS for leg pain, p = 0.040). The ODI and VAS for back and leg pain significantly decreased over time after surgery in both groups (p < 0.001 for all three variables). The patterns of change in the ODI and VAS for back pain during the follow-up period significantly differed between the two groups, suggesting that the PCS group is a potential treatment moderator. However, there was no difference in the ODI and VAS for back and leg pain between the low and high PCS groups 12 months after surgery. In terms of minimum clinically important differences in ODI scores (12.8), 22 patients (40.7%) had an unsatisfactory surgical outcome in the low PCS group and 16 (32.6%) in the high PCS group. There was no statistically significant difference between the two groups (p = 0.539). Pre-operative catastrophising did not always result in a poor outcome 12 months after surgery, which indicates that this could moderate the efficacy of surgery for LSS.

Thyroid vascular conductance: differential effects of elevated plasma thyrotropin (TSH) induced by treatment with thioamides or TSH-releasing hormone.

We have reported previously that thyroid gland blood flow, expressed as vascular conductance (C) per mass, is decreased at very low and increased at very high chronic plasma TSH concentrations, but is apparently unchanged over a broad range of plasma TSH concentrations encompassing normal levels. The aim of the present study was to examine the apparently very steep dose-response relationship between elevated plasma TSH and thyroid vascular C/mass. In the first series of experiments, endogenous plasma TSH concentrations were manipulated by treating male Sprague-Dawley rats (250-280 g) for 6 days as follows: 1) controls (0.5 ml saline/day, ip), 2) propylthiouracil injections (2.0 mg PTU/day, ip), 3) PTU plus partial thyroid hormone replacement (2.0 mg PTU/day and 0.3-0.9 microgram T4 plus 0.075-0.225 microgram T3/100 g.day via continuous sc infusion), or 4) TRH (9-1200 micrograms TRH/100 g.day via continuous iv infusion). The vascular C values of the thyroid gland, salivary gland, kidney, and pancreas were determined using the reference sample version of the radioactive microsphere technique. PTU treatment led to the expected hypothyroidism, increased plasma TSH concentrations (959 +/- 66 vs. 154 +/- 22 ng/dl), increased thyroid weight (9.19 +/- 0.36 vs. 4.60 +/- 0.15 mg/100 g), and increased thyroid vascular C/mass (495 +/- 51 vs. 127 +/- 20 microliters/mm Hg.g/min). PTU-treated rats receiving partial thyroid hormone replacement demonstrated a dose-related suppression of plasma TSH, thyroid weight, and thyroid vascular C. Although, TRH treatments resulted in increased plasma TSH concentrations (e.g. 1200 micrograms TRH, 706 +/- 46 ng/dl) and thyroid weight (e.g. 1200 micrograms TRH, 7.45 +/- 0.41 mg/100 g), thyroid vascular C per tissue mass was not significantly increased after any TRH treatment (e.g. 1200 micrograms TRH, 166 +/- 19 microliters/mm Hg.g/min). Thus, at similarly elevated plasma TSH concentrations, the thyroid vascular C/mass of PTU- and TRH-treated rats constituted separate populations. Both PTU- and TRH-induced thyroid growth were accompanied by similar alterations in thyroid gland morphology (i.e. increased cellular mass with little change in the total amount of colloid). To investigate the mechanisms involved, groups of rats were treated for 6 days as follows: 1) control, 2) PTU or methimazole (25 mg MMI/day, ip), 3) PTU or MMI plus thyroid hormone replacement (1.2 micrograms T4 plus 0.3 microgram T3/d.100 g), 4) TRH (12 micrograms/100 g.day), and 5) PTU or MMI, thyroid hormones, and TRH.(ABSTRACT TRUNCATED AT 400 WORDS)

Cloning of the gene encoding honeybee long-wavelength rhodopsin: a new class of insect visual pigments.

Rhodopsins (Rh), G-protein-coupled receptors with seven transmembrane (TM) helices, form the first step in visual transduction in most organisms. Although many long-wavelength (LW) vertebrate opsin sequences are known, less information is available for invertebrate LW sequences. By a combination of RT-PCR and cDNA library screening, we have cloned and sequenced the honeybee LW Rh gene. The deduced protein is composed of 378 amino acids (aa), appears to have seven TM regions, and contains many of the structures and key aa thought to be important for Rh function. Phylogenetic analysis of this sequence in relation to other invertebrate Rh reveals it to be a member of a new group of insect LW Rh.

'Loop' domain deletional mutant of Bcl-xL is as effective as p29Bcl-xL in inhibiting radiation-induced cytosolic accumulation of cytochrome c (cyt c), caspase-3 activity, and apoptosis.

PURPOSE/OBJECTIVE: To investigate the effect of the enforced expression of p29Bcl-xL or its loop deletional mutant, p18Bcl-xLdelta, on irradiation-induced apoptosis and cell-cycle distribution of HL-60 cells. MATERIALS & METHODS: We compared the irradiation-induced molecular cascade of apoptosis in control human AML HL-60/neo versus Bcl-xL overexpressing (approximately 8-fold) (HL-60/Bcl-xL) and HL-60/Bcl-XLdelta cells that express the loop domain deletional mutant construct (delta26-83 AA) of Bcl-xL. The three cell lines were irradiated with 6MV photons to varying doses up to 20 Gy. Following this, cytosolic cyt c levels, caspase-3 activity, and the Bcl-2 family of proteins were evaluated utilizing Western blot analysis (whole cell lysate or cytosolic S-100 fraction). Apoptosis was assessed by internucleosomal DNA fragmentation, Annexin-V staining and FACS analysis, as well as by morphologic criteria. The cell-cycle effects of radiation were analyzed by flow cytometry. RESULTS: Eight hours following irradiation (12 Gy) of HL-60/neo cells, a marked increase (approximately 8-fold) in the cytosolic accumulation of cyt c in the S-100 fraction was observed. This was associated with the cleavage of caspase-3, as well as the generation of its poly (ADP-ribose) polymerase (PARP) and DFF (DNA fragmentation factor)-45 cleavage activity. Twenty-four to forty-eight hours after irradiation, internucleosomal DNA fragmentation and positive Annexin-V staining (32.3+/-3.3%) was detected in HL-60/neo cells. In contrast, in both HL-60/Bcl-xL and HL-60/Bcl-xLdelta cells, a significantly lower percentage of apoptotic cells (p<0.05) were detected and internucleosomal DNA fragmentation was not induced. Following irradiation, Western analysis neither demonstrated any significant alteration in Bcl-2, p29Bcl-xL, p18Bcl-xLdelta, or Bax; nor induced CD95 (Fas receptor) or Fas ligand expression in any cell type. However, in all cell types, irradiation produced approximately a 2-fold increase in the percentage of cells in the G2/M phase of the cell cycle. CONCLUSION: These results demonstrate that an intact loop domain is not necessary for the full antiapoptotic function of Bcl-xL against irradiation-induced cytosolic accumulation of cyt c, caspase activation, and apoptosis of HL-60 cells. Additionally, the cell-cycle effects of ionizing radiation in HL-60 cells are not affected by enforced expression of Bcl-xL or Bcl-xLdelta.

Lymphomatoid granulomatosis and malignant lymphoma of the central nervous system in the acquired immunodeficiency syndrome.

While primary and secondary malignant lymphomas have been well-documented in the CNS of patients with the acquired immunodeficiency syndrome (AIDS), only one case of lymphomatoid granulomatosis (LG) involving the CNS has been reported. We present three AIDS patients with multiple grossly evident foci of necrosis in the cerebral hemispheres which, on histologic evaluation, were seen to contain angiocentric mixed chronic inflammatory infiltrates with atypical mononuclear cells, luminal thrombosis, and infarction, which is typical of LG. LG was also identified in sections of the lung in one case. Lymphoma was found in other regions of the brain in two cases, suggesting the evolution of LG into cerebral lymphoma. In addition, widespread perivascular multinucleate syncytial giant cells, associated with human immunodeficiency virus (HIV) infection of the CNS, were identified in all patients. The features of LG, its relationship to lymphoma, and the possible etiologic role of an immunodeficiency state or the HIV virus in the pathogenesis of LG are discussed.

Osteoconduction at porous hydroxyapatite with various pore configurations.

To assess the histological response and the reinforcing effects of bone ingrowth within porous hydroxyapatite (HA) implants depending on pore geometry, four kinds of cylindrical-type with parallel linear pores phi50, 100, 300, 500 microm), one kind of sponge-type with irregular interconnecting pores (phi250 microm) and one cross-type with crossing linear pores (phi100 x 120 microm) of porous HA were prepared. Eighty-four rabbits were divided into six groups, and a 5 x 5 x 7 mm sized porous HA block was inserted through the medial cortical window of the proximal tibia. Histomorphological changes were examined using light and scanning electron microscopy. A biomechanical compression test was performed using material test machines. After implantation, the implants showed different histological changes depending on pore geometry. Active osteoconduction was also found in the phi50 microm sized cylindrical-type porous HA. Evidence of remodeling of new bone and bone marrow formation within porous HA was found in the larger cylindrical-types (phi300, 500 microm), and the sponge- and cross-types. The biomechanical test showed that the ultimate compressive strength increased significantly in the phi300 microm sized cylindrical-type, and in the sponge- and cross-types eight weeks after implantation. Porous HA with cylindrical pores could be a useful graft material due to its strength, osteoconductivity and the ease with which its pore geometry can be controlled.

Spinal deformities in Noonan syndrome: a clinical review of sixty cases.

BACKGROUND: Skeletal abnormalities, including spinal deformities, in Noonan syndrome have been described, but no detailed and systematic study of such spinal deformities has been presented in the literature. METHODS: The cases of sixty patients with Noonan syndrome were reviewed retrospectively, and the general appearance, growth disturbance, and mental status of the patients were documented. Spinal deformities were evaluated radiographically, and the frequency, pattern, and severity of the curves were documented. RESULTS: Spinal deformity was present in eighteen (30%) of the sixty patients. Two patients had congenital spinal deformity. Of the remaining sixteen patients with scoliosis, nine had a single thoracic curve, four had a single thoracolumbar curve, and three had a double major curve. Thoracic lordosis was also present in three of these sixteen patients. No patient had only increased kyphosis or lordosis. The mean age when the spinal deformities were detected was nine years; seven deformities were detected before the age of seven years. Overall, surgery was recommended to eleven of the eighteen patients; it was recommended for the treatment of scoliosis (mean, 68.5 degrees; range, 45 degrees to 125 degrees ) in eight patients and for the treatment of an associated thoracic lordosis (8 degrees, 15 degrees, and 18 degrees ) in three. Seven of the eleven patients underwent spinal arthrodesis. The operation was deferred in one patient because malignant hyperthermia developed during the induction of anesthesia. CONCLUSIONS: Scoliosis with an associated thoracic lordosis occurs more frequently in Noonan syndrome than has been reported previously. Since the deformities tend to develop early and are relatively severe, a clinical and, if necessary, radiographic assessment of the spine with careful follow-up should be performed for early detection and treatment of spinal deformity. Although malignant hyperthermia is rare, all patients with Noonan syndrome should be considered to be at risk for the development of this complication before operative treatment.

Surface-induced denaturation of proteins during freezing and its inhibition by surfactants.

In this study, we found that the denaturation of proteins during freezing is closely related to surface-induced denaturation. Several proteins with varying sensitivities to freezing were tested, and the results were compared with susceptibilities to surface denaturation in unfrozen aqueous solution. Also, the influence of the surfactant Tween 80 on the denaturation of each of the proteins was examined during freeze-thawing, as were the effects of Tween 80 and several other surfactants on the stability of lactate dehydrogenase. Proteins formed insoluble precipitates when they were subjected to a quench cooling by dipping in liquid nitrogen, although freezing followed by supercooling caused less precipitation. A strong correlation (r = 0.99) was observed between the tendency of a protein to freeze denature and its tendency to surface denature. Also, the addition of small amounts of surface-active agents protected proteins from both freeze- and surface-induced denaturation. Freeze-induced denaturation of IL-1ra at the ice-water interface during freeze-drying was effectively prevented by adding a small amount of Tween 80. These results suggest that the denaturation of proteins during freeze-thawing can be ascribed primarily to the increase in the area of the ice-water interface during freezing.

Leakage of cement in percutaneous transpedicular vertebroplasty for painful osteoporotic compression fractures.

e analysed the CT scans and radiographs of 76 vertebrae in 49 patients who underwent vertebroplasty for painful osteoporotic compression fractures. Leaks of cement were classified into three types: those via the basivertebral vein (type B), via the segmental vein (type S), and through a cortical defect (type C). More leaks were identified on CT scans than on radiographs by a factor of 1.5 (74/49). Most type-B (93%) and type-S (86%) leaks were missed or underestimated on a lateral radiograph which is usually the only view used during the injection of cement. Of the leaks into the spinal canal, only 7% (2/28) were correctly identified on radiographs. The areas on lateral radiographs where this type of leak may be observed were divided into four zones, and their diagnostic value in predicting a leak into the spinal canal was evaluated. The results showed that cement in the neural foramina had the highest positive predictive value (86%).

Complete extracorporeal removal of metabolic carbon dioxide by alkali administration and dialysis in apnea.

The high mortality rate of patients afflicted with adult respiratory distress syndrome (ARDS) may be due, in part, to the hemodynamic changes and the barotrauma accompanying mechanical ventilation, especially when high positive pressure and oxygen tension are used. Recent experimental evidence suggests that prognosis may be improved by suspending ventilation: in the apneic condition, oxygenation can be maintained by transalveolar oxygen diffusion, while extracorporeal carbon dioxide removal (ECCO2R), achieved with membrane lungs, assures CO2 homeostasis. This technology, however, requires high blood flow rates, and is available only to very few specially equipped centers. We report results of experiments in dogs using an alternative approach to ECCO2R during apnea. Dissolved CO2 was converted to bicarbonate by the systemic infusion of NaOH at the rate of 0.15 mM/kg/min; the generated bicarbonate was then removed by hemodialysis against a bicarbonate-free dialysate, at a blood flow rate of 200 ml/min. Sodium and fluid balance were maintained by ultrafiltration. Observations in five dogs confirm that systemic pCO2, TCO2, and pH can be maintained well within physiologic ranges, and that prolonged apnea followed by full recovery can be achieved with this methodology. Because of the wide availability of dialysis equipment and expertise, and of lower extracorporeal blood flow requirements, ECCO2R by alkali administration and hemodialysis offers a potentially attractive alternative approach to the use of membrane lungs in the apneic therapy of ARDS.

Fibrous dysplasia of the rib presenting as a huge chest wall tumor: report of a case.

Fibrous dysplasia of the rib is not uncommon, but is rarely demonstrated as a huge chest wall mass with severe clinical symptoms. A 59-year-old patient, presenting with a huge, rapidly expanding chest wall tumor compressing the lung, liver and heart accompanied by chest pain and dyspnea, is reported. The tumor was success-fully excised by local radical resection.