Design considerations of form birefringent microstructures

Diffraction characteristics of high-spatial-frequency (HSF) gratings are evaluated for application to polarization-selective computer-generated holograms by the use of two different approaches: second-order effective-medium theory (EMT) and rigorous coupled-wave analysis (RCWA). The reflectivities and the phase differences for TE- and TM-polarized waves are investigated in terms of various input parameters, and results obtained with second-order EMT and RCWA are compared. It is shown that although the reflection characteristics can be accurately modeled with the second-order EMT, the phase difference created by form birefringence for TE- and TM-polarized waves requires the use of a more rigorous, RCWA approach. The design of HSF gratings in terms of their form birefringence and reflectivity properties is discussed in conjunction with polarization-selective computer-generated holograms. A specific design optimization example furnishes a grating profile that provides a trade-off between the largest form birefrin gence and the lowest reflectivities.

RNA degradation in Escherichia coli regulated by 3' adenylation and 5' phosphorylation

Although polyadenylation has commonly been regarded as a special feature of eukaryotic messenger RNA, there are many reports of polyA tails on bacterial RNA (for example, refs 3-8). In Escherichia coli, adenylation mediated by the pcnB gene greatly accelerates decay of RNA I, an antisense repressor of replication of ColE1 type plasmids that resembles highly structured transfer RNA but shows the rapid turnover characteristic of mRNA. Here we report that both 3' adenylation and 5' phosphorylation affect the rate of digestion of RNA I by the 3' exonuclease, polynucleotide phosphorylase; conversely, mutation of the polynucleotide phosphorylase-encoding pnp gene affects ribonuclease acting at the 5' end. Together these findings indicate that enzymes attacking RNA I at its separate termini can interact functionally. Additionally, our discovery that adenylation-mediated degradation by polynucleotide phosphorylase imparts an mRNA-like half-like to RNA I suggests a possible mechanism to account for the rapid decay of mRNA in E. coli.

Meiosis-specific double-strand DNA breaks at the HIS4 recombination hot spot in the yeast Saccharomyces cerevisiae: control in cis and trans

The region of Saccharomyces cerevisiae chromosome III located between the 5' end of the HIS4 gene and the 3' end of the adjacent BIK1 gene has a very high level of meiotic recombination. In wild-type strains, a meiosis-specific double-strand DNA break occurs in the hot spot region. This break is absent in strains in which the transcription factors Rap1p, Bas1p, and Bas2p cannot bind to the region upstream of HIS4. In strains with levels of recombination that are higher than those of the wild type, the break is found at elevated levels. The linear relationship between hot spot activity and the frequency of double-strand DNA breaks suggests that these lesions are responsible for initiating recombination at the HIS4 recombination hot spot.

Intelligent photonic switch based on polarization-selective birefringent computer-generated holograms

We designed and implemented an intelligent reflecting 2 x 1 photonic switch using polarization-selective birefringent computer-generated holograms combined with two polarization modulators. In functional terms, the reflecting switch provides a through path to the output when only one incoming link is transmitting. When both incoming links attempt transmission, the switch turns reflecting, thereby permitting a full exchange of the two incoming streams. The switch can also be set to detect backpropagating beams at its output, to split the beam evenly, and to route the two resulting beams to each of the two inputs. The switch is useful for ultrafast fault-tolerant photonic network applications.

Phenotypic analysis of early hematopoietic progenitors in cord blood and determination of their correlation with clonogenic progenitors: relevance to cord blood stem cell transplantation

Human cord blood (CB) can be utilized as a source of transplantable stem cells. In the clinical setting, the numbers of clonogenic progenitors and nucleated cells are used as indirect measures of the stem cell content of CB samples. In an attempt to define other parameters of engraftment potential, we have determined the numbers of CD34+ cells, and of CD34+ cells co-expressing CD38 and/or HLA-DR in 17 CB samples. At the same time, clonogenic progenitors were assayed in the presence of erythropoietin and different combinations of rhIL-3, rhG-CSF, rhGM-CSF, rh-Steel Factor and medium conditioned by the PU34 primate cell line. Unseparated CB contained a mean of 14.8 x 10(4) CD34+ cells/mL. CD34+CD38-, CD34+DR+ and CD34+DR+ CD38- cells represented 12.2%, 91% and 10% of all CD34+ cells, respectively. Linear regression analysis demonstrated that the total number of CD34+ cells, as well as the different subsets, correlated positively with the numbers of total colonies and day 14 CFU-GM. Furthermore, the proportion of CD34+CD38- cells was significantly higher than has been reported for adult marrow. Cord blood CD34+CD38- and CD34+DR+ cells have a high proliferative potential and are enriched for primitive hematopoietic progenitors. Thus, we conclude that a single collection of CB could be sufficient to engraft an adult recipient, and that quantitation of CD34+ cells and their subsets may be useful in determining the engraftment potential of CB samples.

Polarization-selective computer-generated holograms: design, fabrication, and applications

We constructed polarization-selective computer-generated holograms that apply an independent phase profile during readout by horizontal and vertical light polarizations. These elements are composed of two surface-relief-etched birefringent substrates joined face to face. We describe the design methodology for arbitrary birefringent substrate and gap materials. We show how these holograms are fabricated with standard microelectronics technology and discuss the effects of etching and alignment errors on performance. We demonstrated a diffraction efficiency of 60% with a polarization contrast ratio of >100:1 using a multilevel phase hologram made from two birefringent lithium niobate substrates. We also showed that a single-layer SiO(2) thin-film antireflection coating on all surfaces can reduce reflections from the high-index substrates without significant effect on hologram performance. We also consider some possible applications of this technology and demonstrate experimentally a dual focal-length lens and a self-interconnecting binary 2 × 2 polarization switch.

Longitudinal studies of blood pressure in children

A longitudinal study of six years was conducted to find out the pattern of longitudinal changes of blood pressure and to affirm the "tracking phenomenon" of blood pressure in children in China. We initially measured blood pressure and related parameters of 2,946 children (aged 4-14 years) in 1981 at Fanshan county, Beijing, and then two follow-up remeasurements were conducted in 1985 and 1987, respectively. The results indicated that: the average level of blood pressure increases with age even after adjusting for height and weight; tracking coefficients of systolic blood pressure range from weak to moderate levels, increasing with age. Only 30% of the children whose systolic blood pressure was beyond the 90th percentile of the systolic pressure distribution at the first examination remained at the same region after four years. Multiple stepwise regression was used to determine factors correlated with blood pressure. Our results indicate that systolic blood pressure in children is correlated with body weight, pulse rate, serum glucose and HDL-C, while diastolic blood pressure is correlated only with pulse rate and serum glucose.

[Effect of anti-fibronectin-serum on fertilization capacity of human spermatozoa]

Using the in vitro penetration test, we initially studied effects of anti-fibronectin (FN)-serum on fertilization capacity of human spermatozoa. Owing to the coincubation of anti-FN-serum in a heterologous system (human spermatozoa and zona-free gold hamster oocyte), a certain increase was found in the penetration rate at a low concentration of anti-FN-serum. The penetration rate in the treated group was 20% higher than that in the control group at an anti-FN-serum concentration of 10 microliters/ml (P < 0.05), but at a higher concentration of anti-FN-serum, the penetration rate was not affected. The results suggest that anti-FN-serum can improve the fertilization capacity of human spermatozoa, help to treat the unexplained infertility, and increase the repregnancy rate of vasovasotomy.

Cerebellar role in the load-compensating response of expiratory muscle

The hypothesis that the cerebellum is involved in the load-compensating response of expiratory muscles to expiratory tracheal occlusion was tested in anesthetized cats. A continuous expiratory threshold load (ETL; 5 cmH2O) was applied to elicit consistent phasic baseline electromyographic activity in the transversus abdominis muscle (EMGab). Tracheal occlusion for single expirations (TOE) were applied, and the evoked responses were compared in the intact and decerebellate preparation. Cold blockade of the dorsal spinal column (C5-7) and bilateral vagal inactivation (cold blockade or transection) were employed to determine the role of afferents from the lung, airways, chest wall, and diaphragm in shaping the cerebellar involvement in the motor response. The results showed that 1) decerebellation increased the baseline amplitude of the integrated EMGab (fEMGab) activity (P < 0.05) with little change in expiratory duration, 2) TOE applied after decerebellation markedly increased the expiratory duration compared with the intact values (P < 0.05), with little effect on the peak fEMGab, 3) cooling the dorsal spinal columns (C5-7) did not significantly affect EMGab responses in the intact or decerebellate preparations, and 4) vagal inactivation in the intact or decerebellate preparation significantly eliminated the fEMGab responses to ETL and TOE. We conclude that the cerebellum is involved in the modulation of transversus abdominis activity during ETL and TOE. Vagal afferents provide the major sensory input for the cerebellar modulation of the expiratory loading response.

Cerebellar modulation of ventilatory response to progressive hypercapnia

The cerebellar contribution to the ventilatory response to progressive hypercapnia was examined in 18 anesthetized tracheotomized spontaneously breathing cats. The absolute values for minute ventilation (VE), tidal volume (VT), respiratory frequency (f), inspiratory duty cycle (TI/TT), and mean inspiratory flow (VT/TI) were measured. Progressive hypercapnia [35-65 Torr end-tidal PCO2 (PETCO2)] was induced using the rebreathing method. The respiratory variables at each level of PETCO2 and the slopes of ventilatory (VT and f) responses to hypercapnia were compared across the intact, decerebellate, and decerebellate-vagotomized preparations. In 12 cats, decerebellation preceded vagotomy, and in 6 cats the order of the surgical procedures was reversed. The results show that, compared with intact control, decerebellation had little effect on respiratory variables when PETCO2 was 30-35 Torr. However, during a hypercapneic challenge (40-65 Torr PETCO2), VE and the slope of the VE response were significantly reduced. Bilateral vagotomy increased VT and decreased f but failed to alter the ventilatory response in the PETCO2 range of 35-55 Torr. However, combination of decerebellation and vagotomy, regardless of the surgical order, severely blunted VE (35-65 Torr PETCO2) and the slopes of VE, VT and f responses. When decerebellation followed vagotomy, significant decreases in VT (absolute values and slopes) were noted with little further alteration in f response. We conclude that the cerebellum and its interaction with the vagus nerves play a facilitatory or disinhibitory role in the ventilatory responses to hypercapnia.

Sodium-coupled transport of glucose by plasma membranes of type II pneumocytes

Sodium-dependent absorption of alveolar fluid promotes efficient gas exchange. In animal models, alveolar glucose stimulates phlorizin-sensitive, Na(+)-dependent fluid absorption. It is hypothesized that Na+/glucose cotransporters are localized to apical membranes of type II pneumocytes. Enriched apical and basolateral plasma membrane vesicles were isolated from adult bovine type II pneumocytes. Uptakes of 22Na+ and [3H]glucose by enriched apical and basolateral vesicles were monitored over time. Following addition of external glucose (75 mM), 22Na+ uptake by mannitol-loaded, apically-enriched vesicles was significantly increased over controls. Substitution of interior-negative charge gradients for internally directed Na+ gradients increased glucose-dependent Na+ uptakes even greater. By contrast, external glucose did not significantly promote 22Na+ uptake by enriched basolateral vesicles. External Na+ (75 mM) significantly increased [3H]glucose uptakes by enriched apical vesicles with evidence of overshoot. Phlorizin (100 microM) inhibited both glucose-coupled 22Na+ uptakes and Na(+)-coupled [3H]glucose uptakes. These observations support localization of electrogenic, Na+/glucose cotransporters to enriched apical membranes of mature type II pneumocytes.

Sodium chloride cotransport at the basolateral membrane of type II pneumocytes

Current evidence indirectly supports the hypothesis that Na+/Cl- cotransport occurs at basolateral membranes of type II pneumocytes. To test this hypothesis, enriched apical and basolateral plasma membrane vesicles were prepared from adult bovine type II pneumocytes. Uptake of 22Na+ or 36Cl- by these vesicle populations was monitored over time. Using enriched basolateral vesicles, substitution of formate- for Cl- nearly eliminated 22Na+ uptake, and substitution of Tris+ for Na+ significantly reduced 36Cl- uptake. These observations of Cl(-)-dependent 22Na+ uptake and Na(+)-dependent 36Cl- uptake demonstrated coupling between Na+ and Cl- absorption at the basolateral membrane. Na+/Cl- cotransport inhibitors, furosemide (1 mM) and bumetanide (0.1 mM), also reduced 22Na+ and 36Cl- uptakes by enriched basolateral vesicles. By contrast, furosemide and bumetanide did not affect 22Na+ and 36Cl- uptakes by enriched apical vesicles. Collectively, these observations support localization of Na+/Cl- cotransport to the basolateral membranes of mature type II pneumocytes.

Effects of recombinant human Steel factor (c-kit ligand) on early cord blood hematopoietic precursors

The purpose of this study was to define the effects of recombinant human Steel factor (rhSF) (c-kit ligand) on early and late cord blood hematopoietic progenitors. In the presence of recombinant human erythropoietin (rhEpo), rhSF supported the development of granulocyte/macrophage, erythroid, and mixed colonies from CD34-positive cord blood cells. With increasing concentrations of rhSF, an increase in the number of mixed colonies was observed. This increase was paralleled by a decrease in the number of erythroid colonies, such that the total number of the two colony types was always constant. Similar results were observed when CD34+ cells were cultured in the presence of a combination of rhEpo, rhSF, and rhIL-3. These results indicate that the presence of rhSF enhanced the detectability of the nonerythroid components of mixed colonies. The effect of rhSF on early progenitors (pre-colony-forming units [pre-CFU]) was studied in a two-step assay. In this assay, cells positive for CD34 and resistant to treatment with 4-hydroperoxycyclophosphamide (CD34+/4-HCres) were cultured in suspension for 7 days with rhSF, rhIL-3, or rhSF plus rhIL-3 and then plated in clonogenic assays. Before suspension culture, CD34+/4-HCres cells had a low clonogenic potential (0.37%). After being cultured in suspension, however, these cells gave rise to a large number of colonies of all types when replated. Cells cultured in suspension with the combination of rhSF and rhIL-3 increased significantly in number and gave rise to more colonies, when compared to cells cultured with either factor alone (synergistic effect). In identical experiments, such as effect had not been observed with combinations of rhIL-3 and either rhIL-1 or rhIL-6. Thus, rhSF supports the expansion and differentiation of early progenitors in human cord blood.

Fate of methotrexate albumin microspheres after hepatic intra-arterial injection in dogs

Methotrexate (MTX) albumin microspheres (40 microns) were injected into dog hepatic artery. The MTX levels in the hepatic vein maintained at relatively high concentration for over 3 h, whereas in the case of conventional MTX in saline the drug level decreased sharply soon after injection. After ia MTX in microspheres the MTX levels in liver were higher than those after MTX in saline. The microsphere emboli were entrapped in the hepatic precapillary arterioles. Thrombi were found in hepatic arterioles, with microsphere constituting the core. Hence MTX microspheres hepatic intra-arterial injection may be an effective treatment for patients with liver neoplasms.

[Qing-shen tiao-zhi tablet in the treatment of hyperlipemia in the middle and old aged]

The effect of Qing-Shen Tiao-Zhi (QSTZ) tablet which consisted of Rheum palmatum and Alismatis orientale etc. on serum TC, TG, HDL-C, LDL-C and atherogenic index (AI) was reported in 73 senile hyperlipemic patient, while another 21 patients took Yue Jian Cao (YJC) oil capsule. The results showed that total effective rate was 91.7% in QSTZ group, and 71.43% in the YJC group (P < 0.05). The levels of TC, TG and LDL-C before and after medication showed significant difference, P < 0.01 in QSTZ group and that there was only a few persons those P < 0.05 in control group. About AI, it revealed in QSTZ and control group as P < 0.01 and > 0.05 respectively.

Respiratory load compensation. II. Role of the cerebellum

Effects of inspiratory tracheal occlusion (TO) on respiratory duration (inspiratory and expiratory duration), ventilation, and the peak integrated diaphragm electromyographic (integral of EMGdi) response were tested in 16 anesthetized cats before and after decerebellation with and without vagal input. The same protocols were repeated in the decerebrate preparation. Decerebellation did not significantly affect the baseline or the loaded values [tracheal occlusion (TO)] for respiratory duration, tidal volume, or magnitude of the integral of EMGdi response. Vagal blockade eliminated the load-compensating responses in the intact and the decerebrate preparation. However, vagal blockade in concert with decerebellation resulted in a significant (P < 0.05) reversible inhibition of the peak integral of EMGdi response during inspiratory TO. This suggests that removal of vagal and cerebellar influences during loaded breathing unmasked inhibitory inputs to the respiratory pattern generator. With vagus intact, decerebellation before or after decerebration abolished the attenuation of the peak integral of EMGdi response to TO observed with decerebration alone. We conclude that the cerebellum does play a role in determining the pattern of the respiratory response to TO. This influence may be direct and/or indirect via interaction with information emanating from suprapontine, vagal, and nonvagal sources.

Respiratory load compensation. III. Role of spinal cord afferents

In a previous study, we reported that inspiratory tracheal occlusion (TO) significantly inhibited the motor drive to the diaphragm in a decerebellated bilaterally vagotomized preparation (J. Appl. Physiol. 75:675-681, 1993). The hypothesis to be tested in the present study was that respiratory muscle afferents activated by inspiratory TO provided the inputs responsible for the observed inhibition. Adult cats were anesthetized, tracheotomized, and instrumented with diaphragm electromyographic (EMGdi) recording electrodes. The cerebellum, vagi, and dorsal spinal cord (C2-T2) were surgically exposed. Inspiratory TO was applied before and after cold blockade of the dorsal cord (C6) or dorsal root (C3-6) transection in the intact and decerebellated vagotomized cat. Respiratory timing (inspiratory and expiratory duration) was determined from the EMGdi record, and the peak integrated EMGdi (integral of EMGdi) response was used as an index of respiratory motor drive. Our results showed that 1) cold blockade at the dorsal C6 level in an intact preparation significantly increased the peak of the integral of EMGdi response to TO and was reversible upon rewarming; 2) as previously reported, decerebellation coupled with bilateral vagotomy significantly decreased the peak integral of EMGdi response to TO with no effect on timing; 3) cold blockade (-1 degree C) of the dorsal cord at C6 significantly attenuated this inhibition, and subsequent dorsal rhizotomy at C3-6 completely abolished this inhibition; and 4) decerebellation, cold blockade of the dorsal cord (C6), and dorsal rhizotomy (C3-6) did not significantly affect baseline values in bilaterally vagotomized cats.(ABSTRACT TRUNCATED AT 250 WORDS)

The Escherichia coli pcnB gene promotes adenylylation of antisense RNAI of ColE1-type plasmids in vivo and degradation of RNAI decay intermediates

Previous work has shown that RNase E-mediated cleavage of RNAI, an antisense repressor of the replication of ColE1-type plasmids, relieves repression in vivo by endonucleolytically converting RNAI to a rapidly decaying product. We report that mutations in the Escherichia coli pcnB gene result in a 10-fold prolongation of the half-life of RNAI decay intermediates and also of truncated RNAI primary transcripts lacking sites attacked by RNase E. Using Northern blotting, primer extension analysis, [32P]GTP capping of 5'-triphosphate termini, and PCR amplification methods, we show that pcnB-mediated acceleration of RNAI degradation is associated with posttranscriptional 3' addition of adenosine residues in vivo to native and processed forms of RNAI. Accumulation of antisense RNAI decay products in pcnB mutants potentially explains the reduced copy number of ColE1-type plasmids seen in the mutated bacteria.

Air pollution-type fluorosis in the region of Pingxiang, Jiangxi, Peoples' Republic of China

This paper reports on the epidemiology, environmental factors, geological features, and total amount of fluoride intake by residents of the Pingxiang region in the Peoples' Republic of China where there is a high incidence of endemic fluorosis. The results demonstrate that the type of endemic fluorosis is related to air pollution, the major source of which comes from coal that is burned by the residents in their homes. Air pollution also originates from the small kilns that are used to make bricks and tile. The fluorine content in the coal and mud used to mix the coal is considerably high; the content in the mud used as adobe for tiles exceeds 10,000 mg/kg. During the process of burning coal or baking bricks or tiles, a large amount of nonsoluble fluorine is converted into water-soluble fluoride, which can have major human health effects.

Sodium/proton transport by apical membranes of type-II pneumocytes

Recent studies fail to confirm the coexistence of Na+ channels and Na+/H+ exchange at the apical membranes of lower airway epithelia. Availability of plasma membrane vesicles simplifies the investigation of membrane transport processes. Apical and basolateral plasma membrane vesicles of disrupted type-II pneumocytes were fractionated upon nonlinear, continuous sucrose gradients. To investigate sodium transport, 22Na+ uptake by apical membrane vesicles was assayed in the presence and absence of transmembrane sodium diffusion potentials. Interior-negative sodium diffusion potentials promoted 22Na+ uptake 1.5-fold. Internally-directed H+ gradients or NH+4 gradients inhibited 22Na+ uptake 40-50%. Amiloride (1-1000 microM) inhibited uptake 10-79%. To investigate H+ transport, decay of transmembrane pH gradients was monitored with pH probe acridine orange. In the presence or absence of externally-directed H+ gradients, external sodium promoted internal alkalinization, except in the presence of external amiloride. These observations of amiloride-sensitive, electrogenic Na+ uptake and amiloride-sensitive, electroneutral, Na+/H+ coupling indicate coexistence of Na+ channels and Na+/H+ exchange at the apical membrane of type-II pneumocytes.

Pyrroloquinoline quinone acts with flavin reductase to reduce ferryl myoglobin in vitro and protects isolated heart from re-oxygenation injury

Pyrroloquinoline quinone has been isolated from bacteria and recently has been detected in mammalian tissues and fluids. We report in vitro studies which show that pyrroloquinoline quinone serves as a high-affinity substrate for an erythrocyte "flavin reductase" and that the pyrroloquinoline quinol generated by this catalysis reacts rapidly with ferryl myoglobin radical. Western blot analysis of rat and rabbit heart homogenates detects a cross-reactive protein which has a molecular weight identical to the erythrocyte reductase from the same species. Low concentrations of pyrroloquinoline quinone protect isolated rabbit heart from re-oxygenation injury, serving as an effective tissue-protective agent in this model for cellular oxidative damage. We propose that this tissue protection is due to a pyrroloquinoline quinol-mediated reduction of reactive oxygen species.

Polarization-selective computer-generated holograms

We demonstrate polarization-selective computer-generated holograms with independent phase profiles for the two orthogonal linear polarizations. The holograms are made of two surface-relief-etched birefringent substrates joined face to face. We describe their design and fabrication and present experimental results for dual binaryphase computer-generated holograms fabricated in lithium niobate. The first-order diffraction efficiency varied from 6% to 25%, with as much as 40:1 contrast between polarizations. Such elements can be used in compact optoelectronic systems or combined with electro-optic polarization rotators to make electrically controlled optical elements.

Androgen-induced inhibition of cell proliferation in an androgen-insensitive prostate cancer cell line (PC-3) transfected with a human androgen receptor complementary DNA

A full length human androgen receptor complementary DNA was introduced into androgen receptor-negative PC-3 cells to determine if androgen sensitivity could be established in this cell line and to assess what influence, if any, androgen exposure would have on the growth of these cells. The androgen receptor complementary DNA was inserted into pSG5 in the region controlled by the SV40 promoter. This construct was cotransfected with pSR1neo into PC-3 cells and stably transfected cells were selected and screened for the expression of the androgen receptor. Active expression of the receptor was demonstrated by Western blotting using a rabbit anti-androgen receptor antiserum and by [3H]methyltrienolone binding to cytosol extracts. Saturation ligand-binding analysis revealed the presence of a single class, high affinity (Kd = 0.122 nM) androgen-binding site in cytosol extracts of transfected cells but not in extracts from mock-transfected cells. In cells expressing the transfected androgen receptor, androgen decreased the proliferation rate and cloning efficiency and induced a more differentiated phenotype. These results demonstrate that PC-3 cells have retained the mechanisms required to respond to the activated androgen receptor and that the loss of androgen sensitivity in these cells is due to the lack of functional androgen receptor. This also provides a technique for determining whether androgen-resistant tumor cells contain functional androgen receptors or whether androgen sensitivity is due to abnormalities in downstream signaling pathways. The apparent androgen-induced decreased malignant state of these transfected cells suggests new directions for the treatment of prostate cancer.

Hydrogen peroxide-dependent formation and bleaching of the higher oxidation states of bovine erythrocyte green hemeprotein

The ferric and ferrous forms of bovine erythrocyte green hemeprotein react with hydroperoxides to form higher oxidation state intermediates with absorbance maxima in the Soret region at 426 and 422 nm, respectively. In the absence of an appropriate reductant, these intermediates undergo rapid bleaching reactions. 2,2'-Azinobis(3-ethylbenzthiazoline-6-sulfonic acid) rapidly reduces the intermediate formed by reaction of ferric green hemeprotein with hydrogen peroxide, thereby preventing bleaching and allowing the rate of the intermediate formation to be calculated from the coupled dye oxidation. This rate constant of 70 M-1 s-1 at 23 degrees C is similar to those determined by bleaching and by direct photometric detection of the intermediate. Dihydroriboflavin rapidly reduces the intermediate formed by reaction of ferrous green hemeprotein with hydrogen peroxide, thereby preventing bleaching and allowing the rate of the intermediate formation to be calculated from the coupled dihydroriboflavin oxidation; the rate constant of 2 x 10(4) M-1 s-1 at 23 degrees C is similar to the value calculated by direct detection of the intermediate. The results demonstrate that, in contrast to the reductase activity of its heme-free form, the green heme form of the protein reacts with hydroperoxides to generate highly unstable peroxide complexes.

Respiratory load compensation. I. Role of the cerebrum

This study examines the extent to which the cerebrum and other suprapontine structures modulate the respiratory response to added mechanical resistive loads to breathing. Nine adult cats were anesthetized with thiopental sodium, tracheotomized, and instrumented with diaphragm electromyographic (EMGdi) recording electrodes. Two levels of resistive loads and tracheal occlusion were applied at the onset of inspiration in random order before and after decerebration. The integrated signal of the EMGdi (integral of EMGdi) was used to detect changes in respiratory timing and as an index of respiratory motor drive. The results showed that, compared with intact cats, decerebration did not significantly change baseline values for peak integral of EMGdi, respiratory timing, systemic blood pressure, or arterial blood gases. Although the percent changes in the peak integral of EMGdi elicited by the added loads were still significantly greater than those elicited by unloaded control breaths after decerebration, the magnitude of the responses was significantly attenuated at all load levels compared with the intact preparation. It is concluded that the cerebrum and/or other suprapontine structures provide information that is facilitatory to the respiratory pattern generator with little effect on timing.

Antibody-induced growth inhibition is mediated through immunochemically and functionally distinct epitopes on the extracellular domain of the c-erbB-2 (HER-2/neu) gene product p185

Over-expression of the c-erbB-2 (HER-2/neu) gene product p185 occurs in 30% of breast and ovarian cancers. The p185 protein might serve as a target for serotherapy in that antibodies against different epitopes on the extracellular domain of p185 can inhibit growth of tumor cells in the absence of cellular or humoral effector mechanisms. To define epitopes of functional relevance, 11 monoclonal antibodies (MAbs) were evaluated for their ability to bind to the extracellular domain of p185. Results of competition studies with 125I-labeled and non-labeled antibodies indicated that 10 of 11 epitopes were grouped in a linear array. Antibodies against 7 epitopes inhibited anchorage-independent growth and antibodies against 2 of these epitopes also inhibited anchorage-dependent growth of SKBr3 breast-cancer cells that over-expressed p185. Treatment with antibodies exerted cytotoxic rather than cytostatic effects. When antibodies were used in combination, additive or supra-additive inhibition of anchorage-independent and anchorage-dependent growth was observed between pairs of antibodies. Growth inhibition did not relate to the affinity of the antibody or its isotype. Two antibodies that inhibited both anchorage-dependent and anchorage-independent growth also blocked binding of the HER-2/neu ligand, whereas 5 antibodies that inhibited only anchorage-independent growth had no effect on ligand binding. Inhibition of cell growth did not correlate with internalization of p185 or down-regulation of p185 on the cell surface. Fab fragments of active antibodies could also inhibit anchorage-independent growth of SKBr3. Thus, murine MAbs and their fragments recognized both immunochemically distinct and functionally distinct epitopes on the p185 molecule. Whereas inhibition of anchorage-dependent growth correlated with the ability of antibodies to block ligand binding, inhibition of anchorage-independent growth did not correlate with effects on ligand binding, internalization, cell-surface expression or cross-linking of p185.

The effect of antibodies and immunotoxins reactive with HER-2/neu on growth of ovarian and breast cancer cell lines

OBJECTIVE

Because HER-2/neu is overexpressed in one third of breast and ovarian cancers, we examined the effect of unconjugated monoclonal antibodies (ID-5, PB-3, TA-1) and an immunotoxin (TA-1-ricin) reactive with this protooncogene on the growth of breast and ovarian cancer cell lines.

STUDY DESIGN

The tritiated thymidine incorporation assay was used to examine the effect of unconjugated antibodies on proliferation. A limiting dilution clonogenic assay was used to assess the effect of immunotoxin on cellular cytotoxicity.

RESULTS

Scatchard analysis revealed that OVCA 420, OVCA 429, OVCA 432, and OVCA 433 cells had approximately 10(4) HER-2/neu receptors per cell, whereas the SKOv3 and SKBr3 cell lines expressed 10(5) and 10(6) receptors per cell, respectively. Monoclonal antibody ID-5 caused significant inhibition of tritiated thymidine incorporation in SKBr3, SKOv3, and OVCA 420 cells (p < 0.002). The TA-1-rich immunotoxin significantly inhibited the clonogenic growth of only SKBr3 and SKOv3 cells.

CONCLUSION

HER-2/neu may be a useful target for immunotherapy with unconjugated antibodies and immunotoxins in ovarian and breast cancers that overexpress this protooncogene.

Evidence that NADPH-dependent methemoglobin reductase and administered riboflavin protect tissues from oxidative injury

NADPH-dependent methemoglobin reductase, first detected in erythrocytes sixty years ago, has subsequently been purified and characterized as a methylene blue reductase and a flavin reductase. The reductase plays no role in methemoglobin reduction under normal conditions, but its activity serves as the basis for the treatment of methemoglobinemia with methylene blue or flavin. On-going studies demonstrate that this cytosolic protein is also present in liver and that its primary structure distinguishes it from other known proteins. The bovine erythrocyte reductase tightly binds hemes, porphyrins, and fatty acids with resulting loss of activity. Pyrroloquinoline quinone serves as a high-affinity substrate of the reductase, suggesting that this naturally-occurring compound may be a physiological substrate. The ability of the reductase to catalyze the intracellular reduction of administered riboflavin to dihydroriboflavin suggested that this system might be exploited to protect tissues from oxidative damage. This hypothesis was supported by our finding that dihydroriboflavin reacts rapidly with Fe(IV)O and Fe(V)O oxidation states of hemeproteins, states that have been implicated in tissue damage associated with ischemia and reperfusion. Preliminary studies demonstrate that, as predicted, administration of low concentrations of riboflavin protects isolated rabbit heart from reoxygenation injury, rat lung from injury resulting from systemic activation of complement, and rat brain from damage caused by four hours of ischemia. Data from these animal studies suggest that flavin therapy holds promise in protecting tissue from the oxidative injuries of myocardial infarction, acute lung injury, stroke, and a number of other clinical conditions.

[Hurler syndrome (a case report)]

A case of Hurler syndrome diagnosed by clinical and laboratory examination is reported. The patient's roentgenograms showed the dystrophies of bones, lace-shaped ribs, boat-shaped cranium, fishhook-shaped forefront protrusion of silla trucica. Corneal opacities and high ocular pressure were found in both eyes. VEP measurement suggested the defects of optic nerve. The authors emphasized that visual electric physiological examinations should be used to estimate the visual functions when the patient's refractive medium is opqaue. The differential diagnosis was also briefly discussed.

Effects of radiation and 4-hydroperoxycyclophosphamide on production of G- and GM-CSF by stromal cells

The effects of in vitro radiation and exposure to 4-hydroperoxycyclophosphamide (4-HC) on the production of G- and GM-CSF by different components of the human hematopoietic microenvironment are described. The marrow microenvironment is composed of fibroblasts, endothelial cells, macrophages, and adipocytes. To study the effects of radiation/4-HC on colony-stimulating factor (CSF) production by stromal cells, confluent layers of umbilical cord endothelial cells (EC), marrow fibroblasts (MF), and heterogeneous adherent layers (HAL) derived from long-term marrow cultures were established. These layers were exposed to radiation up to 3000 cGy and/or 100 mumol/ml of 4-HC and subsequently stimulated with IL-1 beta on day 0, 7, or 14 after radiation/4-HC. Following IL-1 exposure conditioned medium (CM) was collected and G- and GM-CSF levels were measured by ELISA and their ability to support colony formation was assessed. G- and GM-CSF levels after exposure to 4-HC and radiation were 12,460 +/- 172 pg/ml and 2268 +/- 160 pg/ml for EC, 2214 +/- 94 pg/ml and 263 +/- pg/ml for MF, and 3168 +/- 316 pg/ml and 356 +/- 34 pg/ml for HALs, respectively. For each cell group there was no significant difference between levels obtained without exposure and levels after exposure to 4-HC and/or radiation (p > 0.6). Comparison of levels obtained from different cell groups showed significant differences with EC media being the highest (p < 0.0001). To test the activity of these measured factors, CM of different sources was used in colony assays of CD 34+ cord blood progenitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Topography of cat medullary ventral surface hypoxic acidification

The topographic relationship between previously identified medullary ventral surface respiratory chemosensitive regions and brain surface extracellular fluid (ECF) acid production during acute hypoxia was explored in anesthetized, paralyzed, and artificially ventilated cats. Glass pH electrodes (0.8-mm diam, sheathed in stainless steel tubing) were mounted in mechanical contact with surfaces of medullary surface or adjacent pyramids, pons, spinal cord, or parietal cortex. Isocapnic hypoxia of 5 min [at arterial O2 saturation (SaO2) = 48 +/- 10%] reduced pH over rostral (Mitchell) and caudal (Loeschcke) areas by 0.12 +/- 0.09 and 0.07 +/- 0.04, respectively (n = 10, P < 0.05). Change in pH (delta pH) was proportional to desaturation with slopes 100 delta pH/delta SaO2 of 0.45 (rostral) and 0.20 (caudal) (R = 0.91 and 0.88, respectively). pH drop usually began within 3 min of hypoxia, became stable between 5 and 15 min, began to rise within 2 min of reoxygenation, and returned to control within 10 min. During equally hypoxic tests, intermediate area (Schläfke), pons, and spinal cord surfaces showed no significant acid shift. Parietal cortex ECF pH dropped more slowly but steadily by 0.079 +/- 0.034 during 20 min at SaO2 = 50% after a small but significant initial alkaline shift, and acidification of cortical surface continued for > 5 min after reoxygenation. We conclude that medullary ventral chemosensitive regions produce more lactic acid during hypoxia than neighboring brain surfaces.(ABSTRACT TRUNCATED AT 250 WORDS)

Study of early hematopoietic precursors in human cord blood

Human cord blood is a source of transplantable stem cells. These stem cells express the antigen CD34, are resistant to treatment with 4-hydroperoxycyclophosphamide (CD34+/4-HCres), and do not give rise to colonies when plated in clonogenic assays. We studied the number of CD34+ cells present in cord blood and developed a two-step assay for early precursors (pre-colony-forming units, pre-CFU) capable of giving rise to committed progenitors. In this assay CD34+/4-HCres cord blood cells were cultured in suspension with different growth factors. After 7 days in suspension the remaining cells were plated in clonogenic assays, for granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), and mixed lineage colony-forming units (CFU-MIX), in the presence of pure factors or a combination of recombinant human (rh) interleukin 3 (IL-3) and medium conditioned by the PU34 primate cell line. Pre-CFU for all precursors were identified. These pre-CFU developed into committed progenitors in response to rhIL-3. The combinations of rhIL-3 plus rh interleukin 1 (IL-1) or rhIL-3 plus rh interleukin 6 (IL-6) did not enhance recovery of progenitors. The developing CFU-GM were responsive to rh granulocyte-macrophage colony-stimulating factor (GM-CSF) and rh granulocyte colony-stimulating factor (G-CSF) but much less so to rhIL-3. BFU-E and CFU-MIX developed in suspension but could only be detected when cells were replated in the presence of a combination of rhIL-3 and PU34 but not rhIL-3 alone. This assay may be useful in evaluating the number of early hematopoietic precursors present in cord blood samples and in defining growth factor combinations that could enhance hematopoietic recovery after cord blood stem cell transplants.

[Chemical constituents from the root bark of Dictamnus dasycarpus Turcz]

Rutaevin was isolated from the root bark of Dictamnus dasycarpus. It has been obtained from genus Dictamnus for the first time.