[Cloning and expression of the gene encoding maltoologosyl trehalose synthase from Sulfolobus shibatae in E. coli]

2.2 kb DNA fragment encoding a novel enzyme, maltooligosyl trehalose synthase (MTSase) was amplified from Sulfolobus shibatae by using PCR technique. The amplified 2.2 kb DNA fragment was inserted into an expression vector, pBV220, to yield the recombinant plasmid pSBGT1. MTSase gene in pBSGT1 was expressed in E. coli. The molecular weight of expressed MTSase detected by SDS-PAGE was about 74 kD, which is conformed with that deduced from nucleotide sequence. The expressed MTSase protein accounted for about 4.4% of the total cell protein. The MTSase from transformants containing pBSGT1 is capable of decreasing DE value, forming non-reducing or less-reducing saccharides when allowed to act on reducing partial starch hydrolysates.

Caspase inhibitors reduce neuronal injury after focal but not global cerebral ischemia in rats

BACKGROUND AND PURPOSE

Studies show that blocking the activation of caspases by the caspase inhibitors z-VAD.FMK and z-DEVD.FMK can reduce ischemic neuronal injury after cerebral ischemia. Because the severity of ischemia was mild in some studies, we tested the efficacy of these caspase inhibitors on moderately severe but transient forebrain and focal ischemic insults in the rat.

METHODS

Various regimens of z-VAD, z-DEVD, and control DMSO were given to rats subjected to either 4-vessel occlusion ischemia (4-VO, 10-minute occlusion, 7-day survival) or distal middle cerebral artery occlusion (MCAo, 90-minute occlusion, 22.5-hour survival). In global ischemia, treatments were given immediately after ischemia (experiment 1) or as preischemic and postischemic treatments (experiment 2). Three focal ischemia experiments were done. Injection times were 60 minutes into ischemia (experiment 1) and 60 minutes into ischemia plus 30 and 120 minutes after ischemia (experiment 2). Experiment 3 was identical to experiment 2 except that a 30-minute preischemia treatment was instituted. Core normothermia was maintained in all experiments during ischemia. However, in the last focal and global experiments, core and brain temperatures, respectively, were also measured after ischemia with telemetry probes. Because hyperthermia accompanied z-DEVD treatment, an extra z-DEVD-treated group (MCAo) was included with temperature clamped at normothermia.

RESULTS

Neither z-VAD nor z-DEVD significantly reduced CA1 injury after global ischemia. In focal ischemia, both drugs significantly reduced infarction, but only in the third experiment, and the prevention of hyperthermia that accompanied z-DEVD treatment did not alter this.

CONCLUSIONS

These results suggest a detrimental role of caspases in moderately severe focal but not global cerebral ischemia.

[A scanning method for detecting colorectal tumors]

OBJECTIVE

To develop a method for survey of colorectal tumors.

METHODS

Mucus obtained by digital rectal examination was smeared on a slice to react with peanut agglutinin labeled by Horseradish-peroxidase.

RESULTS

Brown color was noted in positive reaction. In detecting colorectal tumors, the sensitivity and specificity of the method was 88.2% and 92.5% respectively.

CONCLUSION

The method is effective in detecting colorectal tumors in humans.

Identification of benzo[a]pyrene metabolites in cervical mucus and DNA adducts in cervical tissues in humans by gas chromatography-mass spectrometry

Epidemiological studies indicate that cigarette smoking increases the risk of cervical cancer. To address questions regarding possible mechanisms of tobacco-related cervical carcinogenesis, in a pilot study, using supercritical fluid extraction and a gas chromatographic-mass spectrometric (GC-MS) technique, we detected and characterized benzo[a]pyrene and its metabolites, namely B[a]P-dihydrodiols, phenols and tetraols in cervical mucus samples from eight smokers and non-smokers. Twenty-eight epithelial and stromal cervical tissue samples from seventeen patients undergoing surgery for non-malignant disease were quantitatively analyzed for BPDE-DNA adducts by a GC-MS technique. BPDE-DNA adducts were found in 25 samples. The mean level of BPDE-DNA adducts in epithelial cervical tissues of smokers was nearly two-fold greater than that in self-reported non-smokers; P = 0.02. The mean number of BPDE-adducts (+/- SD) in epithelial cervical tissues of smokers was 3.5 +/- 1.06 adducts/10(8) nucleotides while that in non-smokers was 1.8 +/- 0.96 adducts/10(8) nucleotides. The mean number of BPDE-DNA adducts in stromal cervical tissues of the same subjects was 1.8 +/- 0.96 adducts/10(8) nucleotides in smokers and that in the stromal tissues of non-smokers was 1.4 +/- 1.1 adducts/10(8). These results suggest that polynuclear aromatic hydrocarbons (PAHs) from tobacco smoke and other environmental sources can be transported to the cervix where they are metabolized in the cervical epithelium to ultimate carcinogenic agents, although transport of ultimate carcinogenic metabolites from other organs to the cervix cannot be ruled out. Exposure of cervical epithelia to PAHs and their carcinogenic metabolites suggests a potential role of such carcinogens in the pathogenesis of cervical cancer in humans.

Double-orifice mitral valve with multiple papillary muscles--a report of two patients

Two patients with double-orifice mitral valve, in addition to ventricular septal defect in one patient and mitral insufficiency in the other, and multiplicity of left-ventricle papillary muscles are reported.

Two Properties of a Gene-for-Gene Coevolution System under Human Perturbations

ABSTRACT Recently, the gene-for-gene host-parasite coevolution model of Leonard was extended by incorporating two kinds of perturbations. The first kind was the natural perturbations that include those caused by pathogen migration between the two subpopulations of the host, forward and backward mutations in the host or pathogen populations, and some others. The second kind was human perturbations, such as constantly increasing the percentage of the resistant genotype within the host population each season. In this study, we quantitatively compared the two kinds of perturbations and extended the constantly changing human perturbation to include non-constant perturbations that are more likely to occur in the real world. Two properties of the modified Leonard model were revealed from this study. First, when both human perturbations and natural perturbations are involved, the effects of natural perturbations are very small compared with those of human perturbations. This finding ensures that, in the study of human perturbations, we can simplify the study by ignoring the effects of natural perturbations. Second, through the simulation of nonconstant perturbations, which assumes that the proportion of the resistant genotype of the host population increases over time, we found that the model reproduces the "boom and bust" epidemic cycles that are often found in agroecosystems.

Inhibition of platelet aggregation by bovine endocardial apyrase

AIM

To study the anti-aggregatory effect of bovine endocardial endothelial cell (EEC)-associated apyrase.

METHODS

Cultured bovine EEC was used. Adenosine diphosphate (ADP) was analyzed by reversed phase HPLC, and rabbit platelet aggregation was measured turbimetrically.

RESULTS

Incubation of EEC with ADP 500 mumol.L-1 resulted in a progressive decrease in ADP concentration, which was paralleled by the decrease in platelet aggregating potential of the unmetabolized ADP. In the presence of aspirin (Asp 1 mmol.L-1)-treated EEC 1 x 10(9) cells.L-1, the aggregation of Asp (1 mmol.L-1) and methylene blue (10 mumol.L-1)-treated platelets in response to thrombin 500 U.L-1 and platelet activating factor (PAF 1 nmol.L-1) was markedly inhibited and was reversible, which was very similar to that in apyrase-treated platelets. The supernatants of EEC had no effect on platelet aggregation. EEC inhibited ADP (5 mumol.L-1)-induced platelet aggregation, but failed to inhibit adenosine 5'-O-(2-thiodiphosphate) (ADP-beta-S, an unmetabolizable structural analog of ADP, 15 mumol.L-1)-induced platelet aggregation.

CONCLUSION

ADP hydrolysis by EEC-associated apyrase is a major anti-thrombotic mechanism of bovine EEC.

Characteristics of apyrase (EC 3.6.1.5) on cultured bovine endocardial endothelial cells

Apyrase activities in some tissues and cells, such as peripheral vascular endothelial cells, have been reported, but these in endocardium endothelial cells have not been reported. The present study was to characterise the properties of bovine endocardium endothelial cells (BEEC)-associated apyrase. Apyrase activity was assayed by inorganic phosphate release, which could be inhibited concentration-dependently by NaN3, an apyrase inhibitor. NaF (20 mmol/L), another inhibitor of apyrase, also markedly inhibited the activity. EDTA or EGTA (1 mmol/L) could also inhibit the activity completely. However, the inhibitor for Na+/K(+)-ATPase, ouabain (3 mmol/L) did not affect the enzyme activity. BEEC apyrase activity was dependent on divalent cations (Ca2+ or Mg2+) and pH value.

Identification of a novel zinc finger gene, zf5-3, as a potential mediator of neuroblastoma differentiation

We established a unique parental neuroblastoma cell line, NUB-7, which mimics the bipotentiality of neuroblastoma in vivo along neuronal and Schwann cell lineages following dibutyryl cAMP and retinoic acid treatments, respectively. Differential display identified a putative novel zinc finger gene as a potential differentiation-responsive gene coincident with retinoic acid treatment of NUB-7. This cDNA clone, now designated zf5-3, was mapped to chromosome 19 using somatic cell hybrids, and a larger cDNA clone further localized this gene to band 13.1-13.2 by fluorescent in situ hybridization. zf5-3 possesses 4 characteristic zinc finger DNA-binding motifs as determined by its nucleic acid and proposed amino acid sequence. Expression of zf5-3 is restricted to fetal neuronal, hepatic and renal tissues and their tumor-derived cell lines, including 8/9 neuroblastomas and 2/2 malignant rhabdoid tumors of kidney. The restricted expression in the kidney of zf5-3 to collecting tubules and ureter epithelium is suggestive of an ectodermal histogenesis of malignant rhabdoid tumors of kidney. During development of the fetal human brain, high levels of zf5-3 mRNA are restricted to the mitotically active, undifferentiated neuroblasts. Morphological evidence of overt differentiation was generally accompanied by a marked loss in zf5-3 expression. Therefore, the neuronal tissue expression profile and the down-regulation coincident with retinoic acid-induced neuroblastoma maturation implicate zf5-3 as a potential mediator of their differentiation.

[A preliminary comparision of the abilities of factor analysis and wavelet analysis in reducing noise of absorption spectra]

In this paper, the abilities of factor analysis and wavelet analysis for reducing noise of the absorption spectra are compared. Also, the different joint ways of these two techniques are used to reduce the noise of the same spectra. Some preliminary results are obtained.

Tissue plasminogen activator does not increase neuronal damage in rat models of global and focal ischemia

BACKGROUND

Intravenous tissue plasminogen activator (tPA) is the only approved treatment for acute ischemic stroke. Recent results from both in vitro and in vivo animal model experiments suggest the possibility that tPA is neurotoxic.

METHODS

The authors evaluated the putative neurotoxicity of tPA in both global and focal animal models of ischemic stroke. Global ischemia was induced in male Wistar rats using a modified four-vessel occlusion technique, with percentage neuronal injury assessed at 7 days through necrotic and normal cell count in the CA1 region. Transient focal ischemia was induced in male spontaneously hypertensive rats subjected to middle cerebral artery clipping, with measurement of cortical infarct volume at 24 hours. tPA was administered in 1, 5, or 10 mg/kg doses given intravenously as a 10% bolus, 90% over the following hour, analogous to current human treatment protocols.

RESULTS

In the global model, percent hippocampal injury was 60%+/-23%, 66%+/-26%, 55%+/-26%, and 52%+/-12% in the saline control, 1, 5, and 10 mg/kg tPA groups, respectively. In the focal model, after 120 minutes of ischemia, the control infarct size was 151+/-39 mm3, and for the group given 10 mg/kg of tPA, it was 158+/-28 mm3.

CONCLUSIONS

Despite sublethal insults, with moderate injury induced by ischemia, there was no evidence that increasing doses of tPA exacerbated ischemic injury.

Crystallization and preliminary X-ray diffraction studies of the lipopolysaccharide core biosynthetic enzyme ADP-L-glycero-D-mannoheptose 6-epimerase from Escherichia coli K-12

ADP-L-glycero-D-mannoheptose 6-epimerase is a 240 kDa NAD-dependent nucleotide diphosphosugar epimerase from Escherichia coli K12 which catalyzes the interconversion of ADP-D-glycero-D-mannoheptose and ADP-L-glycero-D-mannoheptose. ADP-L-glycero-D-mannoheptose is a required intermediate for lipopolysaccharide inner-core and outer-membrane biosynthesis in several genera of pathogenic and non-pathogenic Gram-negative bacteria. ADP-L-glycero-D-mannoheptose 6-epimerase was overexpressed in E. coli and purified to apparent homogeneity by chromatographic methods. Three crystal forms of the epimerase were obtained by a hanging-drop vapor-diffusion method. A native data set for crystal form III was collected in-house on a Rigaku R-AXIS-IIC image plate at 3.0 A resolution. The form III crystals belong to the monoclinic space group P21. The unit-cell parameters are a = 98.94, b = 110.53, c = 180.68 A and beta = 90.94 degrees. Our recent results show that these crystals diffract to 2.0 A resolution at the Cornell High Energy Synchrotron Source. The crystal probably contains six 40 kDa monomers per asymmetric unit, with a corresponding volume per protein mass (Vm) of 4.11 A3 Da-1 and a solvent fraction of 70%.

p53-independent role of MDM2 in TGF-beta1 resistance

Transforming growth factor-beta (TGF-beta) inhibits cell proliferation, and acquisition of TGF-beta resistance has been linked to tumorigenesis. A genetic screen was performed to identify complementary DNAs that abrogated TGF-beta sensitivity in mink lung epithelial cells. Ectopic expression of murine double minute 2 rescued TGF-beta-induced growth arrest in a p53-independent manner by interference with retinoblastoma susceptibility gene product (Rb)/E2F function. In human breast tumor cells, increased MDM2 expression levels correlated with TGF-beta resistance. Thus, MDM2 may confer TGF-beta resistance in a subset of tumors and may promote tumorigenesis by interference with two independent tumor suppressors, p53 and Rb.

[The chemical constituents of Epimedium koreanum Nakai]

Three new compounds were isolated from the aerial part of Epimedium koreanum Nakai. On the basis of spectroscopic and chemical evidences, they were elucidated as 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-(4-acetyl) rhamnopyranoside-anhydroicaritin-7-O-beta-D-glucopyranoside, 2-(p-hydroxyphenoxy)-5, 7-dihydroxy-6-prenylchromone, and 7-hydroxy-3, 4, 6-trimethoxy-9, 10-dihydrophenanthrene-2-O-beta-D-glucopyranoside.

Evaluation of buffering capacity and acid neutralizing-pH time profile of antacids

The antacid properties of seven antacids listed in the hospital formulary of a medical center were evaluated with in vitro tests. These included not only the preliminary antacid test and acid-neutralizing capacity test as described in the United States Pharmacopeia (USP XXIII), but also a buffering pH profile test. The preliminary antacid test measured the final pH of a 10-mL solution of 0.5 N HCl 10 minutes after addition of the minimum recommended dose of an antacid, while the neutralizing capacity test measured the amount (mEq) of HCl neutralized by the minimum recommended dose in 15 minutes. The buffering pH profile recorded the pH time course of dynamic simulated gastric fluid neutralization by a dose of an antacid. In the preliminary antacid test, magnesium oxide showed the highest pH (9.52 +/- 0.14, mean +/- standard deviation, n = 3); aluminum phosphate gel yielded a final pH of 2.51 +/- 0.01, thus failing to meet the criteria of an antacid (pH > 3.5). In the acid-neutralizing capacity test, hydrotalcite had the highest neutralizing capacity (28.26 +/- 0.3 mEq), while sodium bicarbonate had the lowest (7.40 +/- 0.12 mEq). In the buffering pH profile test, aluminum-magnesium hydroxide suspensions and hydrotalcite tablets maintained a steady optimum pH (3-5) for around 1.5 hours. One tablet of calcium carbonate, sodium bicarbonate or magnesium oxide could not raise the gastric pH to above 3, but two tablets increased the pH excessively (5.3 to 8.6). The higher dose (two tablets) of aluminum hydroxide hexitol complex could not raise the pH to the optimal level. These findings demonstrate that there is disparity in the antacid effectiveness estimated by the neutralizing capacity test and the buffering pH profile test and suggest that the efficacy of an antacid cannot be accurately predicted from its acid-neutralizing capacity. The dose of antacids greatly influences the neutralizing pH profiles. Aluminum-magnesium compounds appear to provide steadier buffering than carbonate compounds or magnesium oxide.

Long-term efficacy and immune responses following immunization with the RTS,S malaria vaccine

The malaria sporozoite vaccine candidate RTS,S, formulated with an oil-in-water emulsion plus the immunostimulants monophosphoryl lipid A and the saponin derivative QS21 (vaccine 3), recently showed superior efficacy over two other experimental formulations. Immunized volunteers were followed to determine the duration of protective immune responses. Antibody levels decreased to between one-third and one-half of peak values 6 months after the last dose of vaccine. T cell proliferation and interferon-gamma production in vitro were observed in response to RTS,S or hepatitis B surface antigen. Seven previously protected volunteers received sporozoite challenge, and 2 remained protected (1/1 for vaccine 1, 0/1 for vaccine 2, and 1/5 for vaccine 3). The prepatent period was 10.8 days for the control group and 13.2 days for the vaccinees (P < .01). Immune responses did not correlate with protection. Further optimization in vaccine composition and/or immunization schedule will be required to induce longer-lasting protective immunity.

Automated intima-media thickness: the Los Angeles Atherosclerosis Study

Common carotid artery (CCA) intima-media thickness (IMT) from B-mode ultrasound is a widely used measure of early atherosclerosis. This study evaluated within- and between-sonographer reproducibility of automated edge-tracking IMT using a low-cost mobile scanner. B-mode images of the left and right CCA were acquired on two occasions (interval of 2-14 days) by two sonographers for 38 subjects, aged 31-75 y. Reproduciblity error was measured as the mean absolute difference (MAD+/-SEM) and the standard deviation of differences (SDdelta) between repeated measurements. Within-sonographer (MAD=0.027+/-0.006 mm; SDdelta=0.044 mm) and between-sonographer errors (MAD=0.041+/-0.008 mm; SDdelta=0.064) in IMT (mean=0.74, SD=0.14) of a single artery were small compared to those of other protocols. Combined averaging across both body positions and arteries reduced intersonographer MAD by 47% (MAD=0.022+/-0.003 mm; SDdelta=0.029 mm). These data demonstrate that the proposed IMT protocol reduces reproducibility error by more than 50% relative to several protocols used in other major studies.

Dietary calcium, calcium supplementation, and blood pressure in African American adolescents

BACKGROUND

Intake of calcium from the diet is inversely associated with blood pressure in observational studies and animal models but randomized trials in humans have found only small effects of calcium supplementation on blood pressure. A blood pressure-lowering effect of calcium supplementation may thus be restricted to persons with a low intake of calcium from the diet and specific genetic or other characteristics.

OBJECTIVE

A randomized trial was conducted to assess the effect of calcium supplementation on blood pressure in African American adolescents. Rapid growth during adolescence may increase calcium requirements, and avoidance of milk and milk products by some African Americans can result in low intake of calcium.

DESIGN

One hundred sixteen adolescents (65 girls, 51 boys; mean age: 15.8 y) were given calcium (1.5 g/d) or placebo for 8 wk in a randomized, double-blind, crossover design. Blood pressure was measured after 2, 4, and 8 wk. Dietary calcium was determined with a validated food-frequency questionnaire.

RESULTS

The net effect (+/-SE) of calcium supplementation on diastolic blood pressure was a reduction of 1.9 +/- 1.1 mm Hg (P = 0.04, one-tailed t test). Blood pressure reduction was greater in adolescents with lower intake of calcium from the diet (P = 0.003, one-tailed t test for interaction): -4.9 +/- 1.6, -2.3 +/- 1.6, and 1.4 +/- 1.8 mm Hg for change in the lower (0.024-0.067 g Ca/MJ), middle (0.069-0.091 g Ca/MJ), and upper (0.093-0.217 g Ca/MJ) tertiles, respectively. No main effect on systolic blood pressure was detected.

CONCLUSION

These findings suggest that calcium supplementation may lower diastolic blood pressure in African American adolescents with low dietary intakes of calcium.

[Chiari malformations and hydrosyringomyelia]

INTRODUCTION

The association of hindbrain herniation, better known as Chiari malformation, and cystic cavitation of the spinal cord or hydrosyringomyelia has been well described in the literature although there is little consensus regarding its etiology, pathophysiology or optimal treatment.

DEVELOPMENT

Despite a well-accepted and utilized classification system of both Chiari malformation and hydrosyringomyelia, there remains considerable disagreement regarding the proper management of these patients.

CONCLUSIONS

This article reviews several popular theories on the etiology and pathophysiology of this disorder, briefly discusses the clinical features and radiologic findings associated with Chiari malformation and hydrosyringomyelia, and reviews basic surgical techniques for decompression of the cranial-cervical junction and treatment of the hydrosyringomyelia.

[A study of subtotal gastrectomy under the acupuncture combined with epidural anesthesia of small dosage]

Forty-eight cases with benign gastric diseases were operated using acupuncture at Zusanli (ST 36) and Neiguan (PC 6) combined with epidural anesthesia of small dosage (group A, 39 cases), and simple epidural anesthesia of small dosage (group B, 9 cases). The results show that the effect in the group A is better than that in the group B. Namely, the analgesia is stronger, the tractive reaction of internal organs is lighter, the abdominal muscles are more relaxed, the dosage of anesthetic is much smaller and the physiological disturbance is less in the group A.

Gas chromatographic-mass spectrometric determination of benzo[a]pyrene and chrysene diol epoxide globin adducts in humans

The efficacy of a newly developed gas chromatography-negative ion chemical ionization-mass spectrometry-selected ion monitoring (GC-NICI-MS-SIM) assay for measuring globin adducts of benzo[a]pyrene (B[a]P) and chrysene diol epoxides in human was evaluated. In this pilot study, smokers and nonsmokers were selected as exposed and nonexposed groups. Using [2H12]r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyren e ([2H12]trans,anti-B[a]P-tetraol) as an internal standard, B[a]P-tetraols released from globin after hydrolysis and derivatization were quantified by GC-NICI-MS-SIM. Levels of trans-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydrochrysene (chrysene-DE)-globin adducts were estimated by assuming that the recovery and the MS response of the perdeuterated B[a]P-tetraol internal standard reflected the recovery and MS response of chrysene tetraols. The assay was found to be reproducible and sensitive enough to detect both analytes in all samples. The mean levels of B[a]P-tetraols released from the corresponding benzo[a]pyrene diol epoxide (BPDE) globin adducts in smokers were significantly higher than those in nonsmokers, i.e., 2.6 +/- 0.6 SE fmol/mg globin (ranging from 1.2 to 7.8 fmol/mg globin) in smokers and 0.97 +/- 0.05 SE fmol/mg globin (ranging from 0.7 to 1.3 fmol/mg globin) in nonsmokers (P < 0.01). Interestingly, estimated levels of chrysene-DE-globin adducts in the same subjects were about two orders of magnitude higher than those of the globin adducts of BPDE. The mean of the chrysene-DE adducts in smokers was estimated to be 310 +/- 30 SE fmol/mg globin (ranging from 190 to 460 fmol/mg globin) and that in nonsmokers was 250 +/- 25 SE fmol/mg globin (ranging from 110 to 380 fmol/mg). Although the estimated mean of chrysene-DE adducts with globin in smokers appeared to be about 25% higher than in nonsmokers, the difference was not significant (P = 0.06). The results of this study demonstrate the feasibility of the GC-NICI-MS-SIM method for measurement of BPDE globin adducts in humans.

Secondary craniofacial management following initial correction of nonsyndromic craniosynostosis

Marked technical improvements in the surgical management of craniosynostosis have come hand-in-hand with refinements in anesthesia, intensive care, and radiographic image analysis. At the beginning of the second century of the care of these patients, we now have a variety of sophisticated options that represent safer, more physiologically sound and aesthetically more pleasing options for the correction of secondary problems in craniosynostosis.

Modulation of the NMDA receptor by cyanide: enhancement of receptor-mediated responses

The effect of cyanide on the N-methyl-D-aspartate (NMDA)-stimulated increase in cytosolic free calcium ([Ca++]i) was studied by microfluorescence in fura-2-loaded cerebellar granule cells. The response to NMDA was enhanced by NaCN over a concentration range of 20 to 100 microM. These concentrations of NaCN in the absence of NMDA had no effect on basal [Ca++]i. In comparison, NaCN did not affect K+-depolarization-induced [Ca++]i elevation. The NaCN potentiation of NMDA-evoked [Ca++]i elevation was blocked by addition of Mg++ and by the NMDA receptor antagonists 2-amino-5-phosphono-valeric acid and (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohept-5,10-imine maleate. Pretreatment of the cells with pregnenolone sulfate or arachidonate, known modulators of the NMDA receptor, enhanced NaCN action. The voltage-sensitive calcium channel blockers nifedepine and diltiazem did not affect the NaCN-induced potentiation. Additionally, the NaCN action was not altered when tetrodotoxin was used to block Na+ channel-mediated glutamate release. In patch-clamp studies, NaCN increased the amplitude and duration of NMDA-stimulated whole-cell currents. NaCN also enhanced the NMDA receptor response in single-channel patch-clamp experiments. In the outside-out patch recording configuration, NaCN increased the NMDA receptor channel opening frequency without affecting single-channel conductance or mean channel open time. These results indicate that cyanide interacts directly with the NMDA receptor channel complex to enhance receptor-mediated responses.

Management of the ventricular shunt in posterior deformities of the skull in craniosynostosis

The existence of an occipitoparietal cerebrospinal fluid shunt complicates the attempt to remodel posterior skull deformities in craniosynostosis. A composite method to reposition the shunt hardware is described and discussed.

[Three-dimensional echocardiography in evaluation of left ventricular systolic function after mitral valve replacement for chronic mitral diseases with preservation of mitral apparatus]

OBJECTIVE

To assess the global left ventricular performance in 24 normal subjects, 24 patients suffered from mitral valve disease (MVD) with mitral valve replacement (MVR), and 20 patients with mitral valve replacement with preservation of mitral apparatus (MVRP).

METHODS

3DE was used in comparion with the findings of radiography (RNA), two-dimensional echocardiography (2DE), and m-mode (MME).

RESULTS

EF in 10 patients with MVD as compared with RNA, 3DE showed a higher connection coefficient than 2DE and MME. The EF estimated by MME and 2DE showed no difference between NS and MVD groups, there were significant differences when compared with those examined by 3DE. Two, three months after opertion, the VED and VES in group of MVRP were significantly lower than those in group of MVR (P < 0.01), the EF of MVRP group was remarkably higher than that of MVR group (P < 0.05).

CONCLUSION

3DE has the ability to estimate the EF of left ventricle more accurately than 2DE and MMe, especially in the patients suffered from chronic MVD with LV shape deformation. The MVR with preservation of mitral apparatus for chronic MVD is beneficial to maintaining the global systolic function after surgery.

Association of serum total cholesterol with coronary disease and all-cause mortality: multivariate correction for bias due to measurement error

Measurement error in the exposure under investigation is an important but often ignored source of bias in observational studies. The authors examined the impact of measurement error in the association between total serum cholesterol and 16-year coronary heart disease and all-cause mortality in a cohort of 6,137 middle-aged men of Japanese descent in the Honolulu Heart Program (1973-1988). A Cox regression model that enables modeling of survival time with correction for measurement errors in multiple covariates was employed. After controlling for age, body mass index, systolic blood pressure, smoking status, alcohol consumption, dietary cholesterol, and total calorie intake, a difference of one standard deviation (38 mg/dL) in total cholesterol was associated with a significant increase in the risk of coronary disease death (uncorrected hazard ratio = 1.35). After correction for measurement errors in total cholesterol and covariates (except smoking and age), the estimated hazard ratio increased to 1.65 (a 22% increase). A U-shaped relation was observed between total cholesterol levels and the risk of all-cause mortality. This association was then examined with a quadratic model and with a two-slope or V-shaped regression model. In the quadratic fit, the magnitude of the quadratic total cholesterol term increased threefold after the adjustment for measurement error. In the V fit, the hazard ratio of all-cause death corresponding to a change in one standard deviation above 214 mg/dL (the nadir of the V) was 1.15, and increased to 1.49 (by 29%) after the correction. The corresponding hazard ratio of a change in one standard deviation below 214 mg/dL was 1.11, and increased to 1.37 (by 23%) after the correction. The authors conclude that the impact of elevated total cholesterol on the risk of coronary disease and all-cause mortality may be greater than previously estimated with standard methods of analysis. In addition, the correction for measurement error in total cholesterol and covariates did not explain the excess mortality associated with low total cholesterol. More research is needed to elucidate the fundamental issues underlying the U-shaped association, i.e., confounding versus causal implications.

Detection of DNA and globin adducts of polynuclear aromatic hydrocarbon diol epoxides by gas chromatography-mass spectrometry and -3H-CH3I postlabeling of released tetraols

Gas chromatography-negative ion chemical ionization mass spectrometry--selected ion monitoring (GC-NICI-MS-SIM) was employed to detect tetramethyl ether derivatives of tetraols formed upon hydrolysis of DNA and globin adducts derived from diol epoxides of benzo[a]-pyrene (BP) and other polynuclear aromatic hydrocarbons (PAH). The tetramethyl ether derivatives could also be detected by [3H]CH3I postlabeling. The methodology involves the following steps: (1) isolation of DNA or globin; (2) mild acid hydrolysis under vacuum; (3) isolation of the resulting tetraols and derivatization to the corresponding tetramethyl ethers using methyl sulfinyl carbanion and unlabeled or 3H-labeled CH3I; (4) analysis by GC-NICI-MS-SIM or HPLC with radioflow detection. The optimum conditions for hydrolysis of adducts and derivatization of the resulting tetraols as well as the feasibility of this approach for detecting PAH adducts in mice and humans were explored. Using the set of four BP-tetraols that can be formed upon hydrolysis of adducts formed from r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) or r-7,t-8-dihydroxy-c-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (syn-BPDE) as models, the stability of the tetraols under the hydrolysis conditions was investigated. Adducts derived from anti-BPDE yield predominantly the stable r-7,t-8,9-c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (trans-anti-BP-tetraol), while adducts derived from syn-BPDE released cis-syn-BP-tetraol as a major hydrolysis product. Hydrolysis under vacuum significantly increased the recovery of tetraols. Conditions for derivatization of the BP-tetraols as well as tetraols derived from several other PAH anti-diol epoxides were investigated. Tetramethyl ethers proved to be superior derivatives that were stable, easy to prepare in high yields, and detectable with high sensitivity by GC-NICI-MS-SIM (1-50 fmol per injection). Alternatively, these derivatives could be detected by HPLC with radioflow detection if [3H]CH3I were employed for derivatization. The methodology was tested by comparing levels of DNA and globin adducts in mice treated with either unlabeled or 3H-labeled BP. Good agreement was obtained among the GC-NICI-MS-SIM, [3H]CH3I postlabeling, and conventional radiometric methods. Moreover, analysis of human hemoglobin by GC-NICI-MS-SIM resulted in detection of adducts derived from anti-BPDE and r-1,t-2-dihydroxy-t-3,4-epoxy-1,2,3,4-tetrahydrochrysene. The results of this study demonstrate that GC-NICI-MS-SIM of tetramethyl ethers of tetraols formed by hydrolysis of PAH diol epoxide DNA and globin adducts is a promising approach for detection and quantitation of adducts derived from a broad range of PAH.

Regulation of activating transcription factor-1 and the cAMP response element-binding protein by Ca2+/calmodulin-dependent protein kinases type I, II, and IV

The ability of activating transcription factor-1 (ATF1) or the cAMP response element-binding protein (CREB) to enhance transcription can be stimulated by increases in intracellular Ca2+ concentrations. To identify protein kinases which may mediate the ability of Ca2+ to activate these transcription factors, we compared the ability of constitutively active forms of several Ca2+/calmodulin-dependent protein kinases (CaM kinases) to activate ATF1 or CREB. We find that constitutively active CaM kinase I and IV can activate both ATF1 and CREB. In addition, expression vectors for full-length CaM kinase I and IV were able to augment the ability of Ca2+ influx to activate ATF1 or CREB consistent with a role for these kinases in mediating transcriptional responses to Ca2+ signaling. In contrast, CaM kinase II was unable to activate either ATF1 or CREB. These findings provide a potential mechanism that may permit variation in the ability of ATF1 and CREB to respond to changes in intracellular Ca2+ concentrations depending on differences in the relative concentrations of specific CaM kinases.

Antagonism of cyanide toxicity by isosorbide dinitrate: possible role of nitric oxide

In a search for improved cyanide antidotes, the efficacy of isosorbide dinitrate (ISDN), was compared with that of the known cyanide antidote, NaNO2. ISDN was as effective as an optimal dose of NaNO2 in protecting mice against cyanide lethality. To study the mechanism involved, the extent of formation of the cyanide scavenger, methemoglobin, in the action of ISDN was determined. ISDN (300 mg/kg, p.o.) increased methemoglobin from 5 to 10% of total hemoglobin, while, in contrast, NaNO2 (100 mg/kg, i.p.) increased methemoglobin levels to 50% of total hemoglobin. Lowering the dose of NaNO2 to 30 mg/kg reduced methemoglobin levels to approximately 10% of total hemoglobin and in turn nearly abolished its antidotal effect. Decreasing methemoglobin to less than control levels using methylene blue failed to abolish cyanide antagonism by ISDN. Thus, methemoglobin formation by ISDN does not account for its antidotal action. Further studies comparing the respiratory depressant effects of cyanide in the presence of ISDN or NaNO2 also indicated that these two antidotes have different mechanisms of action. Efforts to produce tolerance to the antidotal effect of ISDN against cyanide toxicity were unsuccessful. It is suggested that the well-known ability of ISDN to generate nitric oxide may account for the noted cyanide antagonism.

An inactivating point mutation demonstrates that interaction of cAMP response element binding protein (CREB) with the CREB binding protein is not sufficient for transcriptional activation

The cAMP response element binding protein (CREB) mediates transcriptional activation in response to the cAMP signaling pathway. Several recent studies have suggested that phosphorylation-dependent interaction of CREB with a co-activator designated CREB binding protein (CBP) is a crucial step in mediating transcriptional responses to cAMP. In the present study we have determined that replacement of Ser142 of CREB with Asp greatly decreases the ability of the cAMP-dependent protein kinase to activate CREB. As Ser142 is located within the region of CREB that interacts with CBP, it seemed quite likely that mutations at this site might interfere with binding to CBP. However, both in vitro and in vivo protein-protein interaction assays revealed that replacement of Ser142 with Asp does not interfere with the binding of CREB to CBP. These studies argue strongly that although the binding of CREB to CBP is necessary, it is not sufficient for transcriptional responses to cAMP.

Inhibition of potassium-stimulated dopamine release by the nitric oxide generator isosorbide dinitrate

In PC12 cells, isosorbide dinitrate (ISDN) and S-nitrosol-acetyl-penicillamine (SNAP), both nitric oxide (NO) generators, attenuated K+ (56 mM)-stimulated release of dopamine. The attenuation was not observed with isosorbide, an ISDN analog lacking NO generating capacity. In this model, A23187 (Ca2+ ionophore), Bay K8644 (Ca2+ slow channel agonist) and veratridine (Na+ channel agonist) stimulated dopamine release. Treatment with ISDN enhanced Bay K8644 and veratridine-evoked dopamine release, while ISDN had no significant effect on the A23187 response. Incubation with 8-bromo-cGMP (membrane permeable cGMP analog) had no effect on basal or stimulated dopamine release in these cells, suggesting NO's response was not mediated by cGMP. In additional studies, K+ (56 mM), Bay K8644 and veratridine elevated cytosolic free calcium levels ([Ca2+]i). ISDN reduced K(+)-stimulated increase in [Ca2+]i, but enhanced the increases of [Ca2+]i induced by Bay K8644 or veratridine. These results suggest NO interacts with K(+)-induced membrane depolarization (possibly by inhibiting membrane conductance to K+) to attenuate Ca2+ influx and Ca(2+)-mediated dopamine secretion stimulated by K+.

A functional factor X deficiency

A functional factor X deficiency is described which caused pronounced reduction in the in vitro activation of the extrinsic system while marginally affecting the in vitro activation of the intrinsic pathway. All studies were normal with the exception of a prolonged PT, an elevated factor X antigen, and low factor X activity. Western blot analysis revealed the presence of two factor X species. The abnormal molecule was of higher molecular weight. Interestingly, there was no bleeding associated with this deficiency. The biochemical basis of this defect is currently under investigation.

Enhanced albumin protein separations and protein-drug binding constant measurements using anti-inflammatory drugs as run buffer additives in affinity capillary electrophoresis

An affinity capillary electrophoresis (ACE) method for improving albumin protein separations has been developed. Separation efficiencies for bovine serum albumin (BSA) and human serum albumin (HSA) are dramatically improved by using anti-inflammatory compounds as run buffer additives. The anti-inflammatory drugs used as biospecific ligands to improve the protein separation include ibuprofen (IB), flurbiprofen (FL), and ketoprofen (KE). The binding constants of proteins (BSA and HSA) for the anti-inflammatory ligands (FL and IB) are estimated by ACE and compared to literature values.

Identification of cone classes in Xenopus retina by immunocytochemistry and staining with lectins and vital dyes

The aim of the present study was to determine the number of cone classes in the Xenopus retina. We examined the dimensions and staining properties of cones, utilizing two monoclonal antibodies, COS-1 and OS-2, developed by Szel and Rohlich (1985). Living cones also were reacted with the plant lectins peanut agglutinin (PNA) and wheat germ agglutinin (WGA) and with a fluorescent stilbene dye, DIDS, which binds selectively to red-sensitive cones (Kleinschmidt, 1991; Kleinschmidt & Harosi, 1992a,b). Three cone populations were distinguished based on differences in size and staining properties. Eighty-eight percent of all cones were stained strongly by COS-1, PNA, and DIDS, but weakly by OS-2. The group of cones stained by COS-1 had the largest mean dimensions of outer segment length, width, and oil droplet diameter. COS-1 negative cones were divisible into two groups: a subclass of miniature cones (approximately 4% total cones) was stained strongly by OS-2, PNA, and DIDS. The balance, constituting approximately 9% total cones, were of intermediate size, were not stained by PNA and reacted weakly to OS-2 and DIDS. WGA stained all cones. Large, COS-1+ cones appear to be red-sensitive and belong to the class of anion-tunable cone pigments. We suggest that the intermediate size, COS-1 negative cones are blue-sensitive based on the finding that blue-sensitive chromatic horizontal cells connect to them preferentially (Witkovsky et al., work in progress).(ABSTRACT TRUNCATED AT 250 WORDS)

Differential activation of CREB by Ca2+/calmodulin-dependent protein kinases type II and type IV involves phosphorylation of a site that negatively regulates activity

The cAMP response element-binding protein (CREB) has been shown to mediate transcriptional activation of genes in response to both cAMP and calcium influx signal transduction pathways. The roles of two multifunctional calcium/calmodulin-dependent protein kinases, CaMKIV and CaMKII, were examined in transient transfection studies that utilized either the full-length or the constitutively active forms of these kinases. The results indicate that CaMKIV is much more potent than CaMKII in activating CREB in three different cell lines. It was also found in these studies that Ser133 of CREB is essential for its activation by CaMKIV. Because both CaMKII and CaMKIV can phosphorylate CREB, we pursued further the mechanism by which CaMKII and CaMKIV differentially regulate CREB activity. Mutagenesis studies and phosphopeptide mapping analysis demonstrated that in vitro, CaMKIV phosphorylates CREB at Ser133 only, whereas CaMKII phosphorylates CREB at Ser133 and a second site, Ser142. Transient transfection studies revealed that phosphorylation of Ser142 by CaMKII blocks the activation of CREB that would otherwise occur when Ser133 is phosphorylated. When Ser142 was mutated to alanine, CREB was activated by CaMKII, as well as by CaMKIV. Furthermore, mutation of Ser142 to alanine enhanced the ability of Ca2+ influx to activate CREB, suggesting a physiological role for the phosphorylation of Ser142 in modulation of CREB activity. These data provide evidence for a new mechanism for regulation of CREB activity involving phosphorylation of a negative regulatory site in the transcriptional activation domain. The studies also provide new insights into possible interactions between the cAMP and Ca2+ signaling pathways in the regulation of transcription. In particular, changes in intracellular Ca2+ have the potential to either inhibit or augment the ability of cAMP to stimulate transcription, depending on the presence of specific forms of Ca2+/calmodulin-dependent protein kinases.

Cyanide induces protein kinase C translocation: blockade by NMDA antagonists

Activation and translocation of protein kinase C (PKC) during KCN-induced histotoxic hypoxia was studied in rat brain slices prepared from cerebellum, hippocampus, and cortex. Treatment with 1-10 mM KCN produced a significant increase in PKC translocation and enzyme activity in the particulate fraction of cerebellar and hippocampal slices. In cortical slices, PKC activity was not affected by cyanide treatment. The membrane-associated PKC activity reached a maximum 30 minutes after incubation with KCN and remained elevated up to 60 minutes in both the hippocampus and cerebellum. Pretreatment with MK-801 and APV, specific NMDA receptor antagonists, blocked the cyanide-stimulated translocation in the hippocampus and cerebellum, whereas CNQX, an AMPA/kainate receptor antagonist, did not alter the response. These results demonstrate that cyanide stimulates PKC activation and translocation from the cytosol to membranes in select brain areas and NMDA receptor activation mediates this process.

Characterization of Ca2+/calmodulin-dependent protein kinase IV. Role in transcriptional regulation

We have characterized Ca2+/calmodulin-dependent protein kinase IV (CaM kinase IV), expressed using the baculovirus/Sf9 cell system, to assess its potential role in Ca2+-dependent transcriptional regulation. CaM kinase IV was strongly inhibited in vitro by KN-62, a specific CaM kinase inhibitor which suppresses Ca2+-dependent transcription of several genes, so we tested whether CaM kinase IV could stimulate transcription. Co-transfection of COS-1 cells by cDNA for CaM kinase IV gave 3-fold stimulation of a reporter gene expression, whereas co-transfection with CaM kinase II gave no transcriptional stimulation. Since this transcriptional response was mediated by phosphorylation of cAMP responsive element-binding protein (CREB), we determined the kinetics and site specificities of CaM kinases IV and II for phosphorylating CREB in vitro. CaM kinases IV and II and cAMP kinase (protein kinase A) all had similar Km values for CREB (1-5 microns), but the Vmax of CaM kinase IV was 40-fold lower than those of CaM kinase II and protein kinase A. Although all three kinases phosphorylated Ser133 in CREB, CaM kinase II also gave equal phosphorylation of a second site which was not Ser98. The two CREB phosphorylation sites were separately 32P-labeled, and the abilities of protein phosphatases 1, 2A, and 2B (calcineurin) to dephosphorylate them were tested. Our results show that all three phosphatases could dephosphorylate both sites, and calcineurin was a stronger catalyst for dephosphorylating site 1 (Ser133) than for site 2. These results indicate that CaM kinase IV may be important in Ca2+-dependent transcriptional regulation through phosphorylation of Ser133 in CREB. The fact that CaM kinase II phosphorylates another site in addition to Ser133 in CREB raises the possibility that this second phosphorylation site may account for the suppressed phosphorylation site may account for the suppressed ability of CaM kinase II to enhance transcription through the CRE/CREB system. In addition multiple protein phosphatases, including calcineurin, may exert a modulatory effect on transcription depending on which site they dephosphorylate.

[An epidemiologic study on an outbreak of measles in a particular group of infants]

An outbreak of measles broke out and prevailed in the Beijing Children Welfare House from March 23rd to April 27th, 1992. The 18 victims accounted for 4.8% of the whole infant population in the Welfare House, 11 of them being babies of less than 8 months. One third of the attacked babies were in bad condition and were hospitalized in the observation room. The clinical manifestations indicated that severe symptoms, more complications but favourable prognosis were characteristic of the infant patients. Based on the epidemiologic study and serological test, it was found that the outbreak and spread of the measles originated from outside the Welfare House. It was also found that the vaccinated handicapped infants exposed to natural measles were highly protected. This investigation leads to the conclusion that the cause of this measles outbreak was laid to the vacancy of planning immunization and the existence of a large number of non-protected babies.

Enhanced chiral separation of dansylated amino acids with cyclodextrin-dextran polymer network by capillary electrophoresis

A method for the chiral separation of dansyl-DL-amino acid mixtures using a dextran (M(r) 2,000,000) polymer network containing beta-cyclodextrin (beta-CD) in HPCE was developed. Mixtures of up to seven amino acids could be baseline resolved by this method under neutral pH conditions. Resolution was dependent on the dextran concentration in the polymer network. Temperature effects on the chiral separation were studied. Optimal efficiency and resolution of DL-enantiomeric pairs of amino acid samples were obtained at 25 degrees C. The resolution of different amino acids used in this work decreased with an increase in temperature.

Quantitative relationships between the structure of beta-adrenolytic and antihistamine drugs and their retention on an alpha 1-acid glycoprotein HPLC column

Chromatographic retention parameters of a series of 7 beta-adrenolytics and of 12 antihistamine drugs were determined employing an alpha 1-acid glycoprotein (AGP) high-performance liquid chromatographic (HPLC) column. For the group of antihistamines capillary electrophoretic (CE) retention was additionally measured in the presence of either AGP or human serum albumin (HSA). Two series of solutes hydrophobicity parameters were obtained by reversed-phase HPLC on an immobilized artificial membrane (IAM) column. The solutes studied were subjected to molecular modelling and the structural descriptors obtained were applied in studies of quantitative structure-retention (protein binding) relationships (QSRR). It was found that retention on AGP correlates well with the literature on physiological protein binding data. This retention was demonstrated to depend on hydrophobicity: to a lesser extent in the case of beta-adrenolytics and strongly in the case of antihistamines. Hydrophobicity, along with molecular width and electron excess charge on aliphatic nitrogen was demonstrated to describe retention of antihistamines on AGP. The AGP column is recommended as a convenient reactor for studies of drug-protein interactions. Preliminary CE data do not correlate with the HPLC data.

Project towards no tobacco use: 1-year behavior outcomes

OBJECTIVES

We present 1-year follow-up data from a school-based tobacco use prevention project designed to test the effectiveness of three main components of social influence programs. The components teach refusal skills, awareness of social misperceptions about tobacco use, and misconceptions about physical consequences.

METHODS

Four different curricula were developed and tested in a randomized experiment involving 48 junior high schools. The outcome variables examined were changes in initial and weekly cigarette and smokeless tobacco use 1 year after the intervention.

RESULTS

Analyses indicated that each of the component programs were effective in decreasing both the initial and the weekly use of cigarettes except for the curriculum in which refusal skills were taught. Also, each curriculum was effective in decreasing the initial use of smokeless tobacco except for the one aimed at correcting social misperceptions. Only the combined curriculum showed an effect on the weekly use of smokeless tobacco.

CONCLUSIONS

The combined intervention was the most effective overall in reducing the initial and weekly use of cigarettes and smokeless tobacco. This suggests that different reasons for use exist and need to be counteracted simultaneously. However, since single programs were also effective in reducing all but weekly smokeless tobacco use, any of these components may be worthwhile prevention tools.

Regional and developmental variations of GFAP and actin mRNA levels in the CNS of jimpy and shiverer mutant mice

Gliosis is a common reaction to brain damage. Glial fibrillary acidic protein (GFAP) is a classical astrocytic marker. We have undertaken to measure the level of GFAP-mRNA as an index of gliosis in the brain of jimpy (jp) and shiverer (shi) murine mutants, in which hypomyelination is either severe or moderate, respectively. This study was conducted in five different CNS regions and at different ages. In young jp mutant, the amount of GFAP-mRNA was either normal or lower than in control animals; but after 3 wk of age, the level of GFAP-transcript increased dramatically in all regions examined. A parallel increase in actin-mRNA was also observed, mostly in the diencephalon and to a lesser extent in cortex and spinal cord, but not in the cerebellum and brainstem. In the shi mutant, variations in the amount of GFAP-mRNA were less important than in the jp with two exceptions: In brainstem of 3-wk-old animals, a 2.5-fold increase was observed, and in all the regions but the spinal cord of 12-d-old shi, the levels of GFAP-transcript were 2-5 times lower than in controls. In this mutant, the levels of actin message were usually close to normal, or slightly lower than in controls.

Phosphorylation of cyclic adenosine 3',5'-monophosphate (cAMP) response element-binding protein isoforms by the cAMP-dependent protein kinase

The cAMP response element-binding protein (CREB) mediates transcriptional activation of genes in response to the cAMP signal transduction pathway. There are two different isoforms of CREB, which are generated by alternative RNA splicing. There is evidence that the two isoforms may have different biological activities. As the longer isoform (CREB341) contains a potential phosphorylation site that is not present in the shorter isoform (CREB327), we examined the possible differential phosphorylation of the two CREB isoforms. Recombinant CREB was prepared and used as substrate for phosphorylation by the cAMP-dependent protein kinase in vitro. Phosphopeptide mapping and mutagenesis studies demonstrated that CREB341 contains two sites, serine 133 and serine 98, that can be phosphorylated in vitro by the catalytic subunit of the cAMP-dependent protein kinase. In contrast, CREB327 contains only a single phosphorylation site at serine 119 (equivalent position to serine 133 in CREB341). A kinase titration experiment demonstrated that serine 98 of CREB341 was phosphorylated only at relatively high concentrations of the cAMP-dependent protein kinase. Transient transfection studies were used to test for any possible function of the phosphorylation of serine 98 of CREB341. These studies used GAL4-CREB fusion proteins. We found that mutation of serine 98 to alanine (which would block phosphorylation) has little or no effect on the ability of the CREB fusion protein to activate transcription. These findings suggest that differences in the biological activity of the two CREB isoforms are probably not mediated by differential phosphorylation by the cAMP-dependent protein kinase.

Purification and characterization of N-acetyl-alpha-D-galactosaminidase from Gallus domesticus

Exoglycosidases modify carbohydrate epitopes on glycoproteins and glycolipids. The N-acetyl-alpha-D-galactosaminidase from the domestic chicken, Gallus domesticus, is an important exoglycosidase which degrades the human blood group A epitope. This enzyme has never been demonstrably purified or thoroughly characterized. We have developed a technique to purify this enzyme to homogeneity. The isolated enzyme has a molecular weight of 49.1 kDa by SDS PAGE and 145.0 kDa by gel filtration. The enzyme is highly selective for PNP-N-acetyl-alpha-D-galactosaminide and is inactive against other low molecular weight substrates. The enzyme hydrolyzes the terminal N-acetyl-alpha-D-galactosaminide residues from blood group A2 erythrocytes. Protease activity is below detectable limits. The enzyme has a pH optima of 3.7, a pI of 8.15, is relatively unaffected by ionic strength, and is stable at 4 degrees C.

Targeting of «T» Lymphocytes against Human Hepatoma Cells by a Bispecific Monoclonal Antibody: Role of Different Lymphocyte Subsets

In an attempt to construct bispecific monoclonal antibodies (bimAbs) able to target cytotoxic T lymphocytes against human hepatoma cells, an HGPRT-deficient mutant of the Hepama-6 hybridoma, which produces an antihuman-hepatoma mAb, was directly fused with splenocytes from Balb/C mice immunized by a polyclonal cytotoxic T-cell line. Hybrid hybridomas were selected in HAT medium, and their supernatants were directly screened for the ability to induce IL-2-cultured cytotoxic T lymphocytes to kill hepatoma cells in a 51Cr-release assay. The selected hybrid hybridoma, termed DQ-33, secretes a bimAb, which reacts with a CD3-associated determinant. When resting peripheral-blood lymphocytes were used as effector cells, virtually no cytolytic activity could be induced by DQ-33, whereas phytohemagglutinin-activated lymphocytes that had been expanded in vitro in IL-2-containing medium could be efficiently targeted against hepatoma cells. Targeting by DQ-33 bimAb was analyzed on different subsets of IL-2-cultured lymphocytes. It was evident that CD+4–8+ TCRα/β+ and CD3+4–8-TCRγ/δ+ lymphocytes were efficiently induced by bimAb to lyse human hepatoma cells, whereas no induction of cytolysis could be observed when CD3 + 4+8-TCRα/β+ cells were used as effectors. DQ-33 bimAb was also able to induce lymphokine secretion (IL-2, GM-CSF and TNF-α) by all the different subsets of lymphocytes analyzed in the presence of target cells expressing the relevant antigen, independent of the expression of cytolytic activity.