Glucosamine 6-phosphate deaminase in normal human erythrocytes

In the course of an investigation of hexosamine catabolism in the human malaria parasite, Plasmodium falciparum, it became apparent that a basic understanding of the relevant enzymatic reactions in the host erythrocyte is lacking. To acquire the necessary basic knowledge, we have determined the activities of several enzymes involved in hexosamine metabolism in normal human red blood cells. In the present communication we report the results of studies of glucosamine 6-phosphate deaminase (GlcN6-P) using a newly developed sensitive radiometric assay. The mean specific activity in extracts of fresh erythrocytes assayed within 4h of collection was 14.7 nmol/h/mg protein, whereas preparations from older erythrocytes that had been stored at 4 degrees C for up to 4 weeks had a mean specific activity of 6.2 nmol/h/mg. Characterization of the deaminase by chromatofocusing gave a pI of 8.55. The enzyme was optimally active at pH 9.0 and had a Km of 41 microM. The metal chelators EDTA and EGTA were non-inhibitory; however, inhibition was observed in the presence of metal ions, especially Cu2+, Ni2+ and Zn2+. In addition, the deaminase was also inhibited by several sugar phosphates including the reaction product, fructose 6-phosphate.

A simple method to incorporate the effects of an RF shield into RF resonator analysis for MRI applications

A simple but effective method is proposed to incorporate the effects of a radio-frequency (RF) shield into the analysis of RF resonators for magnetic resonance imaging (MRI) applications. It is shown that the method can predict the resonant frequencies of RF resonators within 5% of the measured values.

In vitro and in vivo activity of topotecan against human B-lineage acute lymphoblastic leukemia cells

Topotecan [(S)-9-dimethylaminomethyl-10-hydroxycamptothecin hydrochloride; SK&F 104864-A, NSC 609699], a water soluble semisynthetic analogue of the alkaloid camptothecin, is a potent topoisomerase I inhibitor. Here we show that topotecan stabilizes topoisomerase I/DNA cleavable complexes in radiation-resistant human B-lineage acute lymphoblastic leukemia (ALL) cells, causes rapid apoptotic cell death despite high-level expression of bcl-2 protein, and inhibits ALL cell in vitro clonogenic growth in a dose-dependent fashion. Furthermore, topotecan elicited potent antileukemic activity in three different severe combined immunodeficiency (SCID) mouse models of human poor prognosis ALL and markedly improved event-free survival of SCID mice challenged with otherwise fatal doses of human leukemia cells at systemic drug exposure levels that can be easily achieved in children with leukemia.

Tritium labelling of amino sugars at C-2 by alkaline epimerization in tritiated water

N-Acetyl-D-[2-3H]glucosamine was synthesized from N-acetyl-D-mannosamine by alkaline 2-epimerization in pyridine containing 3H2O and nickelous acetate. The reaction involves reversible formation of an enol intermediate and therefore also resulted in incorporation of tritium into N-acetylmannosamine. After completed reaction, the two N-acetylhexosamines were separated from other radioactive products and Morgan-Elson chromogens by chromatography on a column of Sephadex G-10, which was eluted with 10% ethanol, and were then separated from each other by chromatography on Sephadex G-15 in 0.27 M sodium borate (pH 7.8). The location of the incorporated tritium was established by treatment of the N-acetylhexosamines with borate under the conditions of the Morgan-Elson reaction, which converts the sugars to Kuhn's chromogen I with concomitant loss of the C-2 hydrogen. As expected, this treatment resulted in the formation of 3H2O, indicating that the tritium was located at C-2. [2-3H]Glucosamine was prepared by acid hydrolysis of the labelled N-acetylglucosamine and was converted to [2-3H]glucosamine 6-phosphate by incubation with hexokinase and ATP. The sugar phosphate was used as a substrate for glucosamine 6-phosphate deaminase (isomerase, EC 5.3.1.10) in a simple 3H2O release assay.

[Prevention of HLA antibody formation in patients with hemato-oncologic diseases by using leukocyte depleted blood preparations]

OBJECTIVE

To determine the effect of transfusion therapy with leukocyte-depleted platelet concentrates in comparison to transfusion support with standard platelet concentrates on the frequency of HLA alloimmunization in hematologic-oncologic patients.

DESIGN

Prospective randomized study.

SETTING

Institute for Transfusion Medicine and Immunohematology at a University Hospital.

PATIENTS

52 hematologic-oncologic patients randomized in 2 groups.

INTERVENTIONS

Exclusive substitution with leukocyte-depleted blood components (platelet concentrates and packed red cells, filter group) or with standard platelet concentrates and leukocyte-depleted packed red cells (control group). Determination of the development of HLA antibodies.

RESULTS

27% of the patients in the control group (4 out of 15) developed HLA antibodies in contrast to zero patients (0 out of 22) in the filter group (p < 0.02).

CONCLUSIONS

The results of this comparative clinical study show that the consequent and exclusive support with leukocyte-depleted blood components is an effective approach for prevention of HLA alloimmunization in long-term substituted patients.

Vermeidung der HLA-Antikörperbildung bei Patienten mit hämato-onkologischen Erkrankungen durch Einsatz leukozytendepletierter Blutpräparate

<i>Ziel: </i>Vergleich der HLA-Immunisierungsfrequenz bei Transfusion von leukozyten-depletierten Thrombozytenkonzentraten im Gegensatz zu Standardthrombozyten-präparaten in der Therapie von hämatologisch-onkologischen Patienten. <i>Design: </i>Prospektive randomisierte Studie. <i>Rahmen: </i>Institut für Transfusionsmedizin und Immunhämatologie einer Universitätsklinik. <i>Patienten: </i>52 hämatologisch-onkologische Patienten, randomisiert in 2 Gruppen. <i>Intervention: </i>Ausschließliche Versorgung mit gefilterten leukozytendepletierten Blutpräparaten (Thrombozyten- und Erythrozytenkonzentrate, Filtergruppe) oder mit Standardthrombozytenkonzentraten und leukozytendepletierten Erythrozytenkonzentraten (Kontrollgruppe). Untersuchung des Auftretens von HLA-Antikörpern. <i>Ergebnisse: </i>27% der Patienten in der Kontrollgruppe (4 von 15) bildeten HLA-Antikörper. Im Gegensatz hierzu waren bei keinem Patienten in der Filtergruppe (0 von 22) HLA-Antikörper nachweisbar (p < 0,02). <i>Schlußfolgerungen: </i>Die Ergebnisse dieser vergleichenden klinischen Studie zeigen, daß der konsequente und ausschließliche Einsatz von leukozytendepletierten Blutpräparaten eine effektive Methode zur Vermeidung der HLA-Immunisierung bei langzeitsubstituierten Patienten ist.

Localization of antigenic determinants recognized by a monoclonal antibody in rat epididymal spermatozoa, with particular reference to sperm maturation

This study localized antigenic determinants recognized by a mouse anti-human sperm monoclonal antibody TüS10 immunocytochemically and immunoelectron microscopically in the rat sperm recovered from the caput and cauda epididymidis. Immunocytochemistry showed that the antibody bound specifically to the plasma membrane overlying the principal piece of membrane-intact sperm from the caput and cauda epididymidis. Demembranation by Triton X-100 significantly decreased the affinity of the monoclonal antibody TüS10 to the caput sperm but did not obviously change that to the cauda sperm. Immunoelectron microscopy with biotin-streptavidin peroxidase complex pre-embedding method confirmed the localization of the antigenic determinants over the cell surface of the principal piece of the membrane-intact spermatozoa from the caput and cauda epididymidis. The demembranated sperm from the caput epididymidis showed no intracellular labelling, while those from the cauda displayed labelling on their external surface of the fibrous sheath. Using monoclonal antibody TüS10 as a probe, we detected different distribution patterns of the antigenic determinants between the spermatozoa in the caput and cauda epididymidis. These results suggest that spermatozoa mature with immunologically detectable changes in the fibrous sheath during their epididymal transit.

[Inhibitory effect of taohong siwu decoction on collagen crosslinking, hyaluronic acid cleavaging and lipid peroxidation]

It has been demonstrated by cytochrome C colorimetry that the Taohong Siwu Decoction (TF) is effective in hydroxyl radical scavenging. TBA colorimetry has proved that TF is effective in inhibiting lipid peroxidation. As detected by viscometry hyaluronic acid cleavage induced by hydroxyl radical can be inhibited by TF. It has been demonstrated by SDS-PAGE method that TF is effective in inhibiting collagen crosslinking.

On the field inhomogeneity of a birdcage coil

A mathematical model is developed for the numerical analysis of birdcage coils constructed using capacitors having different capacitance. With the aid of this model, it is shown that the deviation of some capacitance introduced by tune, balance, and drive mechanisms can cause inhomogeneity in the B1 field produced by the coil. Useful curves and formulae are developed to provide a guideline for the design of birdcage coils.

Movement of retinal along cone and rod photoreceptors

Single isolated photoreceptors can be taken through a visual cycle of light adaptation by bleaching visual pigment, followed by dark adaptation when supplied with 11-cis retinal. Light adaptation after bleaching is manifested by faster response kinetics and a permanent reduction in sensitivity to light flashes, presumed to be due to the presence of bleached visual pigment. The recovery of flash sensitivity during dark adaptation is assumed to be due to regeneration of visual pigment to pre-bleach levels. In previous work, the outer segments of bleached, light-adapted cells were exposed to 11-cis retinal. In the present work, the cell bodies of bleached photoreceptors were exposed. We report a marked difference between rods and cones. Bleached cones recover sensitivity when their cell bodies are exposed to 11-cis retinal. Bleached rods do not. These results imply that retinal can move freely along the cone photoreceptor, but retinal either is not taken up by the rod cell body or retinal cannot move from the rod cell body to the rod outer segment. The free transfer of retinal along cone but not along rod photoreceptors could explain why, during dark adaptation in the retina, cones have access to a store of 11-cis retinal which is not available to rods. Additional experiments investigated the movement of retinal along bleached rod outer segments. The results indicate that retinal can move along the rod outer segment, but that this movement is slow, occurring at about the same rate as the regeneration of visual pigment.

Modulation of transduction gain in light adaptation of retinal rods

The effect of light adaptation on the period of photocurrent saturation induced by a bright stimulating flash was examined in rod photoreceptors of the larval-stage tiger salamander (Ambystoma tigrinum). Using suction electrodes, photocurrent responses to brief flashes were recorded from single, isolated rods in the presence and absence of steady background illumination. Background light decreased the saturation period (T) measured at fixed flash intensity (fixed If) and in this respect light-adapted the saturating response. Effects of the background on responses to weak (i.e. subsaturating) and bright flashes were compared with changes in a parameter, phi = e-delta T/TR*, where delta T is the decrease in saturation period, and where TR* is the slope of the line that relates T and ln If in a given state of adaptation. Dark- and light-adapted responses to flash intensities IDf and ILf, respectively, exhibited similar absolute peak photocurrent and falling-phase kinetics when IDf and ILf satisfied the relation, IDf = phi (ILf + IbTR*), where Ib is the background intensity. It is argued that phi approximates the relative PDE*/R* gain of transduction, i.e. the relative peak level of activated cGMP phosphodiesterase (PDE*) produced by a given, small amount of photoactivated visual pigment (R*). Interpreted on this view, the results imply that light adaptation derives largely from a decrease in PDE*/R gain, rather than from the stimulation of guanylate cyclase activity. The data are consistent with the possibility that modulation of the lifetime of PDE* underlies the background dependence of phi.

Comparative analysis of the sequence and structure of two Drosophila melanogaster genes encoding vitelline membrane proteins

Two Drosophila melanogaster vitelline membrane protein-encoding genes (VM), located at polytene band positions 26A and 34C, have been cloned and comparatively characterized at the nucleotide level. Sequence analysis of genomic and cDNA clones for the two genes, VM26A.1 and VM34C.1, indicates that both are similarly organized with a central highly conserved domain [Scherer et al., Dev. Biol. 130 (1988) 786-788] which is flanked by unrelated regions, and that both genes lack introns. Comparison of the upstream regions reveals that both VM genes contain a hepatmeric element identical to one associated with the D. melanogaster yolk protein-encoding genes (YP). This heptamer occurs in the specific 5' flanking region responsible for ovarian temporal- and tissue-specific control in both VM and YP genes. A putative chorion transcription factor 2 site is also associated with an upstream control element of VM26A.1, but not with any sequenced portion of VM34C.1.

Application of Steffee operation in spinal surgery

Steffee operation is a surgical method of internal fixation for unstable conditions of the spine. Up to March 1991, 32 cases of various spine disorders were treated with the Steffee system in our hospital. These operations brought good results, as 83.4% of the cases received either good or excellent functional and clinical ratings postoperatively. Among patients with spondylolisthesis, the degree of slip correction averaged 58.5% postoperatively. Neurological complications are avoided by accurate localization of the screws.

Noncovalent occupancy of the retinal-binding pocket of opsin diminishes bleaching adaptation of retinal cones

Bright light bleaches visual pigment and leads to a persistent desensitization of isolated rod and cone photoreceptors called bleaching adaptation. Bleaching adaptation results from the combined effects of pigment depletion and adaptational modulation of certain cellular reactions in the visual transduction cascade. Here, we present evidence that in solitary cone photoreceptors isolated from the salamander retina, the latter effect is due to the presence of free opsin in the outer segment. Also, we demonstrate that this "opsin adaptation" can be reversed by treating the cells with synthetic retinoids similar to 11-cis retinal but having polyene chains too short to form protonated Schiff base attachments to opsin.

A comparative study on the solid phase capture--platelet test, platelet adhesion immunofluorescence test and lymphocytotoxic test

The sensitivity, specificity and reproducibility of the solid phase capture-platelet test (CPT) were compared with those of the platelet adhesion immunofluorescence test (PAIFT) and the lymphocytotoxic test (LCT). This study shows that CPT has a higher sensitivity than PAIFT (P < 0.001) and LCT (P < 0.01). The specificity was 86% lower than LCT (100%) (P < 0.01). Both the CPT test and PAIFT were comparable with regard to reproducibility (100%, 92%). The solid phase assay is easier to handle than PAIFT and LCT, allowing identification of HLA as well as of platelet specific antibodies. It is an efficient antibody screening test.

Separation of sugars by ion-exclusion chromatography on a cation-exchange resin

A method for the separation of N-acetylmannosamine and N-acetylglucosamine is described, which consists of chromatography of the two sugars on a column (30 x 1 cm) of the cation-exchange resin, Dowex 50W-X2, in borate buffer at pH 7.8. N-Acetylmannosamine is eluted near the void volume, while N-acetylglucosamine emerges in a more retarded position. It is postulated that the separation occurs as a result of the combined effects of ion exclusion and gel permeation. Thus, in borate solution, N-acetylmannosamine presumably exists largely as a negatively charged complex and is therefore excluded from the sulfonated polystyrene matrix, while N-acetylglucosamine occurs mainly as the free sugar in the equilibrium mixture and, being a neutral compound, has free access to the porous resin. The proposed mechanism for the separation was supported by the finding that glucose and glucose 6-phosphate could also be separated on a column of the same resin, with water as the eluent.

Developmental control elements in the promoter of a Drosophila vitelline membrane gene

DNA fragments from the 5' flanking region of Drosophila melanogaster vitelline membrane gene VM26A1 were fused to hsp/lacZ reporter genes, reintroduced via P-element-mediated germ line transformation, and functionally assayed by histological staining for beta-galactosidase activity. A developmental control element capable of promoting the basic vitelline membrane (VM) expression pattern was found within a 176-bp region. Additional multiple genetic control elements were found to be involved in modifying the level and spatial pattern of reporter gene expression but these required the 176-bp element in order to function. Unexpectedly, in isolation this 176-bp core element also promotes abnormal expression of the reporter gene in border cells of stage 8 and 9 egg chambers. This abnormal border cell expression is apparently suppressed in the native gene by an adjacent negative control element.

Health behavior and outcomes in sequential pregnancies of black and white adolescents

OBJECTIVE

To examine the relationships among parity, preterm delivery, fetal growth retardation, and prenatal care utilization in first and second adolescent pregnancies.

DESIGN

A longitudinal, retrospective study in which obstetric, behavioral, and sociodemographic data were used to examine birth outcomes of 737 low-income black (80%) and white (20%) teenagers delivering first and second singleton infants at 20 or more weeks' gestation.

SETTING

Public health clinics in Jefferson County, Alabama, between January 1983 and February 1990.

MAIN OUTCOME MEASURES

Mean birth weight, preterm delivery, fetal growth retardation, Apgar scores, and perinatal mortality.

MAIN RESULTS

In their second pregnancies, adolescents presented 2.8 weeks later for care (P = .0001) and made fewer total clinic visits. Mean infant birth weight increased by 91 g (P = .0005). This increase was significantly associated with an increase in maternal prepregnancy body mass index. The rate of fetal growth retardation decreased (P = .0001) and the rate of preterm delivery increased (P < .02) in the second pregnancy. The rate of recurrence of fetal growth retardation was 13% and the rate of preterm delivery was 46%.

CONCLUSIONS

Poorer utilization of prenatal care and high risk for recurrence of adverse outcomes are characteristic of adolescents' second pregnancies and should be considered in teenage pregnancy intervention programs.

Separation of N-acetylglucosamine and N-acetylmannosamine by chromatography on Sephadex in borate buffer

Several procedures have been used previously for the separation of N-acetylglucosamine and N-acetylmannosamine, which are based on the difference in strength of the borate complexes of the two N-acetylhexosamines and include paper chromatography on borate-treated paper, paper electrophoresis in borate buffer, and anion-exchange chromatography of the borate complexes. In the present study, we have observed that the two sugars, despite their identical size in noncomplexed form, may also be separated by gel chromatography in borate buffer. Nearly complete resolution was obtained by chromatography on a column (1.5 x 117 cm) of Sephadex G-15, which was eluted at room temperature with 0.27 M sodium borate, pH 7.8 (prepared from H3BO3 by addition of NaOH), at a flow rate of 10 ml/h. This procedure complements existing methods for the separation of N-acetylmannosamine and N-acetylglucosamine and has the advantage that it can be carried out on a relatively large preparative scale.