[Total body irradiation etoposide followed by autologous hematopoietic stem cell transplantion for non-Hodgkin's lymphoma]

OBJECTIVE

To evaluate the therapeutic effectiveness and safety of total body irradiation(TBI) and Etoposide(Vp-16) as a preparative regimen for autologous hematopoietic stem cell transplantation(AHSCT) with non-Hodgkin's lymphoma(NHL).

METHODS

Twenty-four patients with intermediate and high grade NHL underwent AHSCT. They achieved complete remission (CR) or partial remission (PR) after induction chemoradiotherapy. Twenty-three patients had first CR or PR, and one third CR. Ten patients underwent autologous bone marrow transplantation (ABMT) and 14 autologous peripheral blood stem cell transplantation (APBSCT). The preparative regimen was TBI 800(700-850) cGy/Vp-16 757(323-1140) mg/m2.

RESULTS

At a median follow-up of 22.5(2-92) months, the one-year disease free survival(DFS) was 86.7% (13/15), 3-year, 5-year and 7-year DFS were 80.0% (12/15) in patients with CR before AHSCT. The DFS was 66.7% (4/6) in patients with PR before AHSCT. The patients who had relapsed before AHSCT(3 cases) did not reach DFS. The hematopoietic function recovery was rapid in APBSCT than ABMT.

CONCLUSION

The clinical results of AHSCT for intermediate and high grade NHL who achieved CR or PR after induction therapy are satisfactory. The TBI/Etoposide is an effective and safe preparative regimen for AHSCT in NHL patients.

Presence, isolation and characterization of yolk DNA from chicken eggs

Yolk DNA was detected with immunocytochemistry in fertilized chicken eggs. Yolk spheres were purifield with Ficoll-400 density gradient centrifugation, followed by extraction of DNA therein. Yolk DNA is sensitive to various restriction endonucleases. but shows no obvious bands, demonstrating its sequence heterogeneity. There is only a little, if any, methylated CpG in yolk DNA. judgmg from MspI and HpII digestion. Southern blot indicated that the sequence of yolk DNA accounts for a small portion of that of genomic DNA. Its uniqueness suggests that yolk DNA may play a crucial role in early development of chickens.

Mechanistic studies of the biosynthesis of paratose: purification and characterization of CDP-paratose synthase

The 3,6-dideoxyhexoses can be found in the cell wall lipopolysaccharide of Gram-negative bacteria, where they have been shown to be the dominant antigenic determinants. All naturally occurring 3,6-dideoxyhexoses, with colitose as the only exception, are biosynthesized via a complex pathway that begins with CDP-d-glucose. Included in this pathway is CDP-paratose synthase, an essential enzyme in the formation of the 3,6-dideoxy sugars, CDP-paratose and CDP-tyvelose. Recently, the gene encoding CDP-paratose synthase in Salmonella typhi, rfbS, has been identified and sequenced [Verma, N., and Reeves, P. (1989) J. Bacteriol. 171, 5694-5701]. On the basis of this information, we have amplified the rfbS gene by polymerase chain reaction (PCR) from S. typhi and cloned this gene into a pET-24(+) vector. Expression and purification of CDP-paratose synthase have allowed us to fully characterize the catalytic properties of this enzyme, which is a homodimeric protein with a preference for NADPH over NADH. It catalyzes the stereospecific hydride transfer of the pro-S hydrogen from the C-4' position of the reduced coenzyme to C-4 of the substrate, CDP-3,6-dideoxy-D-glycero-D-glycero-4-hexulose. The overall equilibrium of this catalysis greatly favors the formation of the reduced sugar product and the oxidized coenzyme. Interestingly, this enzyme also exhibits a high affinity for NADPH with a much smaller dissociation constant (Kia) of 0.005 +/- 0.002 microM compared to the Km of 26 +/- 8 microM for NADPH. While this unusual property complicated the interpretation of the kinetic data, the kinetic mechanism of CDP-paratose synthase as explored by the combination of bisubstrate kinetic analysis, product inhibition studies, and dead-end competitive inhibition studies is most consistent with a Theorell-Chance mechanism. The present study on CDP-paratose synthase, a likely new member of the short-chain dehydrogenase family, represents the first detailed characterization of this type of ketohexose reductase, many of which may share similar properties with CDP-paratose synthase.

Cloning, sequence analysis, and distribution of rat metallocarboxypeptidase Z

A cDNA encoding human carboxypeptidase Z (CPZ), a novel metallocarboxypeptidase, was recently cloned (Song and Fricker, J. Biol. Chem., 272, 1054, 1997). In the present study, a cDNA encoding the rat homolog of CPZ was identified. As with the human form, rat CPZ contains an N-terminal domain of 120 amino acids that has 20% to 30% amino acid identity with the "frizzled" domain found on proteins that interact with Wnt, a protein involved in tissue polarity in early embryogenesis. Sequence analysis showed rat and human CPZ to be highly conserved within the frizzled domain (77% amino acid identity), the carboxypeptidase domain (91%), and the C-terminal 28 residues (78%). The entire rat CPZ protein has high sequence similarity with human CPZ (81% amino acid identity), moderate sequence similarity to human carboxypeptidase N (45%), human carboxypeptidase E (41%), and human carboxypeptidase M (33%), and less sequence similarity with other metallocarboxypeptidases. Northern blot analysis showed rat CPZ mRNA to be abundant in the placenta, with low to moderate levels in the brain, lung, thymus, and kidney. The BRL3A rat liver cell line and the PC12 rat adrenal cell line express high levels of CPZ mRNA. In situ hybridization analysis indicated that CPZ is expressed only in specific cell types. For example, in the brain, CPZ mRNA is present in leptomeningeal cells, but not in the majority of other cell types. This distribution in leptomeningeal cells is shared by AEBP1, a recently reported member of the metallocarboxypeptidase gene family. However, the distribution of CPZ and AEBP1 differ in pituitary and thyroid. Taken together, these studies suggest that CPZ functions in a range of cell types.

[Effects of orthodontic treatment on the shape of upper dental arch of patients after surgical operation of cleft lip and palate]

Occlusal casts were measured and analysed in the following groups: orthodontic group(9 subjects treated orthodonticly after surgical operation of the cleft lip and palate), untreated group (10 subjects untreated orthodonticly after surgical operation), normal group(10 young subjects with normal occlusion). The results were that the upper dental arch length and width increased evidently (P < 0.01) in the orthodontic group and almost returned to normal; in contrast, the upper dental arch length and width were inhibited in the untreated group; there were significant differences among the normal occlusion group, the orthodontic group, and untreated group (P < 0.01). The results suggest that during the period of growth and development, the shape of the upper dental arch of the patients can be evidently improved by the orthodontic treatment after the surgical operation of cleft lip and palate.

[Effect of yuxintong on ECE, NOS gene expression and immunohistochemical studies on cooper-zinc-SOD in ischemic myocardium in experimental dogs]

OBJECTIVE

To explore the effect of Yuxintong (YXT) on the endothelin converting enzyme (ECE) and the nitric oxide synthase (NOS) gene expression levels and cooper-zinc-superoxide dismutase (SOD) activity.

METHODS

The acute myocardial ischemia models were reproduced in anesthetized dogs by ligating the left coronary artery at the middle of anterior descending branch. The ECE and NOS gene expressions were observed by in situ hybridization and the cooper-zinc-SOD was studied by immunohistochemical and image analysis.

RESULTS

It was found that the transfer of ECE mRNA was greatly increased, while that of NOS mRNA was greatly decreased in ischemic my ocardium, but the YXT could enhance the expression levels of NOS mRNA and inhibit the over expression of ECE mRNA in ischemic myocardium in dog. Meanwhile, the cooper-zinc-SOD immunohistochemistry was significantly weakened in ischemic myocardium, but the YXT could evidently increase SOD activity in experimental ischemic myocardium.

CONCLUSIONS

It suggested that YXT had notable protection on experimental ischemic myocardium and was definitely valuable on prevention and treatment of coronary heart disease.

[Comparison of pharmacological studies on ootheca Mantidis]

The pharmacological effects of three species of Ootheca Mantidises were compared. The results indicate that Tenodera sinensis can increase the index of testis and thymus gland, and has an antidiuretic effect in mice; Statilia maculate can prolong the swimming time and ordinary pressing anoxia, increase the index of spleen and thymus gland, raise the temperature in mice, decrease the content of LPO in liver of the hypercholesteremia rats, and has an antidiuretic effect; Hierodula patellifera can increase the index of testis and thymus gland, raise the temperature in mice, and decrease the content of LPO in liver of the hypercholesteremia rets. The LD50 of the three species of Ootheca Mantidises are all over 320 g/kg.

Postoperative blood flow monitoring after free-tissue transfer by means of the hydrogen clearance technique

The hydrogen clearance technique was introduced for monitoring postoperative blood flow after free-tissue transfer in this prospective clinical study. This technique allows unlimited repeatable quantitative measurements of tissue blood flow in milliliters per minute per 100 gm of tissue at any site including buried flaps. In this study a real-time blood flow measuring system (Ameflow, Ameda, Switzerland) was employed. Two thousand eight hundred and twenty-three blood flow measurements were carried out on 72 free-tissue transfers, which were performed on 71 patients. Nine of these 72 flaps showed vascular complications (12.5 percent), including arterial thrombosis in 6.9 percent (n = 5), hematoma in 4.2 percent (n = 3), and venous thrombosis in 1.4 percent (n = 1). Complications as well as uneventful postoperative cases were monitored correctly by the hydrogen clearance technique in all cases, reaching sensitivity and specificity values of 1.0 for this technique in our study. Furthermore, all complications could be detected earlier by the hydrogen clearance technique than by clinical monitoring alone, which allowed flap salvation in 7 of 9 cases and a resulting permanent failure rate of free-tissue transfer of 2.8 percent (n = 2). From our data we conclude that the hydrogen clearance technique is a promising tool for postoperative blood flow monitoring after free-tissue transfer. For experimental pathophysiologic and pharmacologic studies of tissue blood flow in flaps, further evaluation of our measuring device including comparative studies with other established techniques is highly recommended.

[Observation on TXB2 and 6-keto-PGF1 alpha in serum of patients with cor pulmonale]

To know the changes of TXA2 and PGI2 in serum of patients with cor pulmonale, the levels of their stable metabolites TXB2 and 6-keto-PGF1 alpha in serum were examined in 28 patients with cor pulmonale during alleviation, 29 patients with cor pulmonale during exacerbation before and after treatment and 10 healthy subjects. TXB2 and 6-keto-PGF1 alpha were 109.74 +/- 56.14 ng/L and 54.76 +/- 35.62 ng/L respectively in healthy subjects; TXB2/6-keto-PGF1 alpha = 2.004. The TXB2 level of patients with cor pulmonale at every stage was higher than that of healthy subjects (P < 0.05-0.01). Patients with cor pulmonale during exacerbation had the highest TXB2 level of 709.22 +/- 354.49 ng/L, which decreased to 408.24 +/- 289.41 ng/L (P < 0.05) after treatment with traditional Chinese medicine combined with western medicine and the decreased level as such was not significantly different from that during alleviation (333.14 +/- 324.14 ng/L). The 6-keto-PGF1 alpha level in patients with cor pulmonale at every stage was not significantly different from that of healthy subjects. Since TXB2 increased, the value TXB2/6-keto-PGF1 alpha of patients with cor pulmonale was greater than that of healthy subjects. It is most likely that chronic hypoxia and hypercapnia lead to prostaglandin release in the lung of patients with cor pulmonale; hypoxia and hypercapnia become more severe during exacerbation resulting from infection; which lead to increased prostaglandin release, then high TXB2 level ensue as the result. TXB2 decreases after amelioration of hypoxia during treatment. But the change of 6-keto-PGF1 alpha is not obvious.

[Effect of yuxintong capsule on plasma endothelin and serum nitric oxide in acute myocardial ischemia dogs]

Effect of Yuxintong (YXT) capsule on plasma endothelin(ET), serum nitric oxide (NO) and creatine phosphokinase (CPK) activity in experimental acute myocardial ischemia dogs were observed. The results indicated that in acute myocardial ischemia dogs, the serum CPK activity and plasma ET level increased and serum NO level decreased significantly. In comparing with control, YXT not only could reduce significantly the increased plasma ET content and serum CPK activity, but also increase markedly the producing and releasing of NO, P < 0.05-0.001. Therefore, it could protect the myocardia from ischemic damage, the efficacy of YXT was positively dose dependent.

The effect of inhaled K+ channel openers on bronchoconstriction and airway microvascular leakage in anaesthetised guinea pigs

Since orally administered K+ channel openers may have cardiovascular side effects, it is possible that inhaled administration would be preferred for the treatment of asthma. We have investigated whether inhaled levcromakalim and HOE 234 inhibit histamine-induced bronchoconstriction and airway plasma exudation in anaesthetised guinea pigs. We have also investigated whether inhaled HOE 234 inhibits the bronchoconstriction and plasma exudation induced by vagus nerve stimulation, which is due to the release of tachykinins from sensory nerves. Lung resistance was measured by airway resistance (RL) computed from airway and transpulmonary pressures and plasma exudation by measurement of Evans blue dye extravasation. Inhaled levcromakalim (25 mu g/ml) had a short duration of action, being effective against histamine-induced bronchoconstriction 2 min after pretreatment, but not at 10 min. Inhaled HOE 234 (25 mu g/ml) was similarly effective against histamine-induced bronchoconstriction but had a longer duration of action. Inhaled levcromakalim partially attenuated histamine-induced plasma extravasation in small airways, but not in the trachea or main bronchi, whereas inhaled HOE 234 had no effect. HOE 234 protected against non-adrenergic non-cholinergic nerve-induced bronchoconstriction, but had no effect on neurogenic- or substance P-induced plasma extravasation in the airway. Inhaled K+ channel openers protect against induced bronchoconstriction, but provide little or no protection against plasma exudation, possibly because of an increase in airway blood flow. In addition, inhaled HOE 234 had no effect on neurogenic leakage, suggesting that its vagal inhibitory effect on bronchoconstriction was on airway smooth muscle, rather than on release of neuropeptides from sensory nerves.

[An in vivo study on DNA-protein crosslinks induced by nickel chloride]

DNA-protein crosslinks (DPC) in the white blood cells (WBC) and lung tissues were detected with a new and sensitive 125I-post-labelling technique in male Sprague-Dawley rats injected peritoneally (i.p.) with nickel chloride (NiCl2). Results showed DPC in the WBC and lungs of the rats increased significantly 20 hours after acute exposure to NiCl2. Multiple small doses (10 mg/kg i.p., twice a week for three weeks) of NiCl2 had similar effects as single large dose (30 mg/kg). It suggested DPC could be used as a biomarker to reflect genotoxicity to the WBC and lungs caused by nickel compound. DPC in the WBC increased more obviously than that in the lungs after exposure to NiCl2, and both correlated to each other. It showed DPC in the WBC can be used as a surrogate to indicate genotoxic lesions in target organs.

Expression of genes associated with antibiotic extrusion in Pseudomonas aeruginosa

We cloned the gene(s) associated with multiantibiotic resistance in Pseudomonas aeruginosa from a mutant with elevated drug extrusion. The strain harboring cloned gene accumulated less amount of ofloxacin than the strain without the clone. By using Southern and northern blot analyses, we investigated whether multiantibiotic resistance is caused by gene amplification or overexpression. We found that all our multiantibiotic resistance is caused by gene amplification or overexpression. We found that all our multiantibiotic resistant mutants isolated earlier overexpressed mRNA homologous to the cloned gene(s). Overexpression of the 41 KDa and 110 KDa inner and the 50 KDa outer membrane proteins were detected. Other multiantibiotic resistant mutants including the nalB mutant overexpressed the mRNA and the membrane proteins, but the nfxB and nfxC mutants did little. We concluded that low antibiotic accumulation in the multiantibiotic resistant mutants is attributable to overexpression of the antibiotic extrusion machinery.

[Cell-mediated immune function in NPC patients treated with cimetidine]

Cimetidine (CMD), an H2 receptor antagonist, was used in combination with radiation for the treatment of patirnts with nasopharyngeal cancer (NPC). In patients treated with radiotherapy alone, there was an increase in the number of CD4+ T cells and in NK cell activity. In patients received combined treatment of radiation and CMD, in addition, there was a decrease in CD8+ T cells with an increase in CD4/CD8 ratio and an increase in IL-2 production. The NK cell activity was also stronger in the latter group. The results suggest that CMD helps restore cell-mediated immunity in NPC patients radiation treated.

Mechanistic studies on CDP-6-deoxy-L-threo-D-glycero-4-hexulose 3-dehydrase identification of His-220 as the active-site base by chemical modification and site-directed mutagenesis

CDP-6-deoxy-L-threo-D-glycero-4-hexulose 3-dehydrase (E1) purified from Yersinia pseudotuberculosis is a pyridoxamine 5'-phosphate (PMP) dependent iron-sulfur-containing enzyme which catalyzes the C-O bond cleavage at C-3 of its substrate leading to the formation of 3,6-dideoxyhexose. This enzyme is rapidly inactivated by diethyl pyrocarbonate (DEP) at pH 6.0 and 25 degrees C. The inactivation of E1 by DEP, which is reversible upon treatment of hydroxylamine, appears to be attributable solely to the modification of histidine residues. The fact that coincubation of E1 with its substrate gave almost total protection against DEP inactivation and that only one less histidine residue was modified in the presence of substrate strongly suggested that inactivation is due to the modification of only one reactive histidine residue which resides in or near the active site of E1 and is critical for E1's activity. Sequence alignment between the translated ascC (E1) gene and several representative pyridoxal 5'-phosphate (PLP)/PMP dependent enzymes revealed that three of the four invariant residues, glycine, aspartate, and arginine found in all other aminotransferases, are conserved in the E1 sequence (G169, D191, and R403). However, the highly conserved lysine is replaced by a histidine residue (H220) in E1. In order to test whether H220 plays an essential role in E1 catalysis, H220N mutant was constructed and the encoding protein was found to exhibit nearly identical physical characteristics as the wild-type E1. Interestingly, the mutant protein had lost most of its catalytic activity, and one less histidine residue was modified upon treatment of H220N-mutated protein with DEP. Such a single-point mutation also impaired E1's capability of catalyzing the solvent hydrogen exchange at C-4' position of the PMP coenzyme. Our findings strongly suggested that H220 is most likely the active-site base which abstracts the C-4' proton from the PMP-substrate adduct and initiates the catalysis. Furthermore, E1's preservation of other invariant residues found in many PLP/PMP dependent enzymes allowed a speculation of their roles in E1 catalysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Mechanistic studies on CDP-6-deoxy-delta 3,4-glucoseen reductase: the role of cysteine residues in catalysis as probed by chemical modification and site-directed mutagenesis

CDP-6-deoxy-delta 3,4-glucoseen reductase (E3), which catalyzes the reduction of the C-3 deoxygenation step during the formation of CDP-ascarylose, a 3,6-dideoxyhexose found in the lipopolysaccharide of Yersinia pseudotuberculosis, has been expressed at high level in Escherichia coli (670 times over the wild-type strain). This flavoenzyme, which also contains one plant ferredoxin type [2Fe-2S] cluster, was inactivated by 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and N-ethylmaleimide. In both cases the inactivation followed a pseudo first order kinetics. The second order rate constant for the reaction of DTNB with E3 was 0.25 mM-1 min-1 at 20 degrees C, pH 8.0. Detailed characterization of the inactivated enzyme showed that neither the flavin nor the [2Fe-2S] cluster was altered during inactivation. Since this inactivation was reversible by treating the inactivated enzyme with 1 mM D,L-dithiothreitol (DTT), it was concluded that only cysteine residues were modified during inactivation. Analysis of the inactivation using the method developed by Tsou revealed that two cysteines react with DTNB at similar rates and modification of either one is enough to impair E3's activity. Tryptic digestion of E3 labeled with N-ethyl[2,3-14C]maleimide, followed by fractionation of the digest by high performance liquid chromatography, gave two labeled peptides, both of which were separately isolated as a pair of interconvertible diastereoisomers. Sequence analysis of these labeled peptides allowed the identification of Cys-75 and Cys-296 as the reactive cysteine residues. Interestingly, the C75S and C296S mutant proteins exhibit identical physical and comparable catalytic properties as the wild-type enzyme. Since Cys-296 is a conserved residue in the NAD(P) binding domain of enzymes belonging to the same class, this residue may be involved in stabilizing the charge-transfer complex between E3 and NADH, thus facilitating hydride transfer from the nicotinamide nucleotide to flavin. A chemically modified Cys-75 which is immediately adjacent to the [2Fe-2S] center in E3 may prevent the proper juxtaposition of the redox centers and thus impede electron transfer leading to enzyme inactivation. These results may be useful for placing constraints on the peptide folding comprising the active site of E3 for electron transfer between NADH, FAD, and the [2Fe-2S] center.

Serological survey of nasopharyngeal carcinoma in 21 cities of south China

This paper reports the results of serological survey of 318,912 persons for nasopharyngeal carcinoma (NPC) in 21 cities and counties of south China. There were 8,441 persons with positive VCA-IgA antibody (single item positive) of EB virus (EBV), with a rate of 2.65%. In these VCA-IgA positive persons, 287 persons also had positive EA-IgA (double items positive) of EBV. The overall positive rate was 0.09%. 100 cases of NPC were found and 87 of them (87.0%) were in early stage. NPC found in the group with single item positive accounts for 1.19%, but the rate in the group with double items positive was 19.16% (55 cases). In NPC patients with double items positive, 49 cases were in early stage (89.1%). In 100 cases of NPC found, 45 cases appeared with negative EA-IgA, only with positive VCA-IgA, which indicated that for diagnosis of NPC, sensitivity of EA-IgA was lower than that of VCA-IgA, but its specificity was higher. Therefore, both can increase the detecting rate and early diagnosis rate of NPC. The age of people checked varied with different antibody positive rate and NPC detecting rate. The three items showed a positive correlation. The results are compatible with those of the prospective study for NPC in Wuzhou City, Guangxi, China. The method for NPC serological diagnosis can be extended and applied to raise the NPC detecting rate and early diagnosis rate at secondary prevention. And, it is further proved that there is a close relationship between NPC and EBV.

[Study on the optimums for Pseudomonas maltophilia HCG receptor expression]

According to the design of orthogonal experiment, the optimums for expression of Pseudomonas maltophilia with HCG receptor were studied by radioassay. The results showed that the optimums influencing the specific binding percentage of Pseudomonas maltophilia were the cultures of No. 3 solid medium added with 0.5% galactose and incubated at a temperature of 37 C for 72 hours. Under these conditions, the binding percentage of Pseudomonas maltophilia to HCG was higher than those under other conditions.

Further characterization of endometrial integrins during the menstrual cycle and in pregnancy

OBJECTIVE

To profile the changes in integrin expression in cycling and pregnant endometrium.

DESIGN

Immunohistochemistry was performed on endometrium from proliferative, early, and midsecretory phase and early pregnancy using a blinded panel of monoclonal antibodies directed against integrins. Closer examination of the cycle-dependent integrins was performed in 112 patients throughout the cycle and from the first trimester of pregnancy.

SETTING

An academic teaching hospital.

PATIENTS

Ovulatory women or women undergoing pregnancy termination.

MAIN OUTCOME MEASURE

Staining intensity of each antibody in epithelial or stromal cells.

RESULTS

Certain integrins were present constitutively throughout the menstrual cycle whereas others were expressed only during the luteal phase. Four integrins increased in the decidua of pregnancy. The timing of expression of the two cycle-dependent integrins (alpha 4 beta 1 and alpha v beta 3) framed the putative window of implantation and suggests a role in establishment of uterine receptivity.

CONCLUSIONS

Our findings confirm the patterns of endometrial integrins and suggest important roles for integrins in the process of implantation and decidualization.

[Studies on the mechanism of Polyactin A's enhancive effect on NK cell activity]

It has been shown that the novel immunopotentiator Polyactin A (PAA) developed in China can augment NK cell activity. In order to further understand the mechanism of PAA effect on NK activities, we measured the binding and lytic capacities of peripheral blood lymphocytes (PBL) isolated from normal subjects and patients with esophageal carcinoma against K562 target cells by using a single cell cytotoxicity assay. Morphologically the ultrastructures of NK cells of normal subjects and the patients on PAA were also studied. The results showed that: (1) Preincubation PBL of normal subjects on PAA at 100 micrograms/ml for 4 hours could increase the rate of NK lysis with no effect on the binding rate. The binding capacities of PBL of patients with esophageal carcinoma were lower than those of normal subjects. Pretreatment PBL of patients with esophageal carcinoma could significantly increase not only the rate of NK lysis, but also the binding rate. (2) Study on the processes of conjugation and cytolysis by using light microscopic morphology, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) found that effector cells include not only large granular lymphocytes (LGL), but also non-LGL bound to target cells. One effector cell could simultaneously make contacts with more than one target cell. It was found that PBL/K562 contacts could be morphologically divided into two types in the SEM and TEM. Either effector cell protrusions were pushed deep into pouches and lacunae of the target cell surface or a wide area of intimate cell-to-cell contact was formed. Effector/target cell contact is a prerequisite for NK lytic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

CDP-6-deoxy-delta 3,4-glucoseen reductase from Yersinia pseudotuberculosis: enzyme purification and characterization of the cloned gene

The 3,6-dideoxyhexoses, usually confined to the cell wall lipopolysaccharide of gram-negative bacteria, are essential to serological specificity and are formed via a complex biosynthetic pathway beginning with CDP-D-hexoses. In particular, the biosynthesis of CDP-ascarylose, one of the naturally occurring 3,6-dideoxyhexoses, consists of five enzymatic steps, with CDP-6-deoxy-delta 3,4-glucoseen reductase (E3) participating as the key enzyme in this catalysis. This enzyme has been previously purified from Yersinia pseudotuberculosis by an unusual procedure (protocol I) including a trypsin digestion step (O. Han, V.P. Miller, and H.-W. Liu, J. Biol. Chem. 265:8033-8041, 1990). However, the cloned gene showed disparity with the expected gene characteristics, and upon expression, the resulting gene product exhibited no E3 activity. These findings strongly suggested that the protein isolated by protocol I may have been misidentified as E3. A reinvestigation of the purification protocol produced a new and improved procedure (protocol II) consisting of DEAE-Sephacel, phenyl-Sepharose, Cibacron blue A, and Sephadex G-100 chromatography, which efficiently yielded a new homogeneous enzyme composed of a single polypeptide with a molecular weight of 39,000. This highly purified protein had a specific activity nearly 8,000-fold higher than that of cell lysates, and more importantly, the corresponding gene (ascD) was found to be part of the ascarylose biosynthetic cluster. Presented are the identification and confirmation of the E3 gene through cloning and overexpression and the culminating purification and unambiguous assignment of homogeneous E3. The nucleotide and translated amino acid sequences of the genuine E3 are also presented.