[Effects of composite blood-activating decoction on adhesive function of bone marrow stroma cells in radiation injured mice]

OBJECTIVE

To evaluate the effect of commonly used "blood activating and stasis-removing" Chinese herbal drugs on adhesive function of bone marrow stroma cells in acute radiation injured mice.

METHODS

After irradiation by 8 Gy 60Co gamma-ray, each mouse was intraperitoneally injected immediately with 0.2 ml 100% composite blood-activating decoction (CBAD) twice a day for 6 days. On the 7th day, the femura were taken and the bone karyocyte (BMC) suspension was made. According to long term bone marrow culture procedure, on the 12th day, the fibroblastic colony forming units were counted, and on the 28th day, the adhesion of culture stroma cells to normal murine BMC was observed.

RESULTS

The adhesion of culture stroma cells to normal murine BMC was 67.8 +/- 17.2% in normal group, while in CBAD group, it was 55.8 +/- 10.5%. The difference was insignificant (P > 0.05). In the control group, the value was 47.7 +/- 13.6%, which was significantly lower than that in normal group (P < 0.02).

CONCLUSION

The commonly used "blood-activating and stasis-removing" Chinese herbal drugs can enhance the adhesive function of bone marrow stroma cells in acute radiation injured mice.

[Relationship between enteroviral infection and dilated cardiomyopathy]

To investigate the role of enteroviral infection in the patho genesis of dilated cardiomyopathy (DCM), we used the nested reverse transcription polymerase chain reaction to detect enteroviral RNA in 21 myocardial specimens and 17 peripheral blood samples from patients with DCM and 21 patients (controls) with cerebral trauma. Enteroviral RNA was detected in 9 of 21 myocardial tissues and 6 of 17 blood samples, whereas all controls myocardial samples were negative. In addition, antibodies of coxsackievirus group B were detected in 4 of the 17 patients with DCM by neutralization test. The present study suggested that DCM might be associated with persistent enteroviral infection.

Sequence, specificity and crystallization of an oestrone-3-glucuronide antibody (3910)

We describe the specificity profile and V region sequences of a high-affinity monoclonal antibody (mAb), 3910, directed against oestrone-3-glucuronide (E3G). Inhibition studies show that the D-ring is critical for steroid specificity, while the glucuronic acid attached to the A ring is required for high binding affinity, suggesting that both 'ends' of the E3G ligand are recognized. The VH domain is encoded by a gene from the VH7183 family, while VL appears to be encoded by the Vk5.1 gene (kappa II subgroup) with a deletion of six residues from complementarity-determining region-1 (CDR1). The VH CDR3 is 10 amino acid residues in length, of which D/N contributes five residues. Comparison of VH CDR of 3910 with those of mAb against progesterone (DB3) and digoxin (26-10, 40-50), for which crystal structures have been determined, suggests that aromatic side chains are important for E3G binding and that tyrosine residues H50, H97 and H100 may interact with the ligand. The Fab fragment of 3910 has been crystallized in its native and steroid (E3G and oestriol-3-glucuronide) complexed forms. An X-ray diffraction data set to 3 A resolution has been collected for the native Fab.

Motif III S5 of L-type calcium channels is involved in the dihydropyridine binding site. A combined radioligand binding and electrophysiological study

The alpha1 subunit of L-type voltage-dependent Ca2+ channels (alpha1C) has been shown to harbor high affinity binding sites for the Ca2+ channel dihydropyridine (DHP) modulators. It has been suggested by a number of investigators that the binding site may be composed of III S6 and IV S6. Evidence with chimeric channels indicated the possible involvement of III S5 in DHP binding. Site-directed mutations were introduced in motif III S5 region of the alpha1C, changing the amino acids to their counterparts in the DHP-insensitive alpha1A channel. The mutant channels were expressed both in HEK 293 cells and in Xenopus oocytes. Equilibrium binding and electrophysiological studies showed that the Thr1006 to Tyr substitution produced a mutant channel with at least 1000-fold decreased affinity in [3H](+)isopropyl-4-(2,1, 3-benzoxadiazol-4-yl)-1,4-dihydro-(2, 6-dimethyl-5-methoxycarbonyl)pyridine-3-carboxylate (PN200-110, isradipine) binding and in sensitivity of R(-)-4(2,1, 3-benzoxadiazol-4-yl)-1,4-dihydro-2, 6-dimethyl-5-nitro-3-pyridincarboxylic acid isopropylester (R202-791) in terms of inhibition of current through the L-type voltage-dependent Ca2+ channels. Replacing Gln1010 with Met resulted in more than a 10-fold decrease in binding affinity for [3H](+)PN200-110 and in the potency of channel modulation by S202-791. Four additional mutations in this region also lead to a slight but statistically significant increase of KD values for [3H](+)PN200-110 binding. The binding and electrophysiological results show that certain residues of the transmembrane segment III S5 are important in contributing to the DHP binding "pocket" and are critical for DHP binding and for its calcium channel effect.

[A survey on mother's nutritional knowledge-attitude on the feeding of young child in Guangdong province]

A survey on mother's nutrition knowledge-attitude on the feeding of young child was conducted in Guangdong province in 1995 among 414 mothers of 0 to 18 months old children. The results showed that the nutritional knowledge-attitude level of the mothers was low in both city and township. Only 51% of them had qualified level. The level of general nutritional concepts and the nutritional knowledge-attitude during weaning period were significantly lower than that of breastfeeding and follow-weaning. It suggests that the promotion of nutritional education in the feeding of young children is urgent in Guangdong province especially in township and rural area. It is necessary to focus on the improvement of nutritional knoweledge in weaning period and general nutrition concepts.

Protoplast culture and plant regeneration ofPinellia ternata

A study was undertaken to develop a protoplast regeneration system for pinellia. A yield of 19 29 x 10(5) protoplasts/g F. W. could be obtained from cell suspension cultures incubated in a digestion enzyme solution with 2% cellulase Onzuka R-10, 10% pectinase (Sigma), 0.01% pectolyase Y23. K8P and modified MS media were used to culture protoplasts in: a) liquid, b) liquid-solid double layer, or c) agarose embedded protoplast culture. The former two were conducive to colony formation from protoplast-derived cells. The frequency of cell division was about 8% after 3 days in culture. Gradually adding fresh medium of lower osmotic pressure into the medium for protoplast culture favored cell division. Calli (1-2 mm in diameter) formed after 30-40 days in culture. The calli transferred onto medium supplemented with KT (0.5 mg 1(-1)) and NAA (0.2 mg 1)(-1)) could regenerate plants after 40-50 days. Of 47 plantlets transplanted into plots, 29 flowered and were fertile.

Oligodendroglial signal transduction systems are regulated by neuronal contact

Previous reports indicate that oligodendrocytes express signaling systems activated by classical neurotransmitters. Several signaling systems linked to mobilization of intracellular calcium have been demonstrated, and some of these are developmentally lost in vitro and in vivo. The experiments described here use oligodendrocyte-neuron cocultures to examine the effects of neuronal contact on the expression of these signaling pathways. Neonatal rat cerebral oligodendrocytes in contact with dorsal root ganglia (DRG) neurites responded to bath application of histamine, ATP, carbachol, glutamate, or bradykinin with increases in intracellular Ca2+ concentration. Similar results were obtained in coculture with superior cervical ganglia neurons. Preventing neuronal contact by transection of DRG neurites significantly reduced the percentage of oligodendrocytes responsive to each ligand, with the exception of bradykinin responsiveness, which was unaffected. Oligodendroglia isolated from adult rat spinal cord were also examined for responsiveness to these neuroligands. Few isolated adult oligodendroglia were responsive to these ligands, and coculture with DRG neurons failed to restore responsiveness. Neuroligand responsiveness was not induced in oligodendrocytes maintained 8 days in purified culture before establishment of cocultures. A significant reduction in the number of neuroligand-responsive oligodendroglia was noted for histamine, carbachol, glutamate, and ATP after including tetrodotoxin for the final 6 days of coculture. These results suggest that both neuronal contact and neuronal activity contribute to the maintenance of functional neurotransmitter-activated signaling pathways coupled to mobilization of intracellular calcium in oligodendrocytes.

Crystallization of a complex between the Fab fragment of a human immunoglobulin M (IgM) rheumatoid factor (RF-AN) and the Fc fragment of human IgG4

Rheumatoid factors (RF) are the characteristic autoantibodies found in patients with rheumatoid arthritis. They recognize epitopes in the Fc region of immunoglobulin G (IgG) and are often of the IgM isotype. In order to analyse the nature of RF-Fc interactions, we have crystallized a complex between the Fab fragment of a human monoclonal IgM rheumatoid factor (RF-AN) and the Fc fragment of human IgG4. The stoichiometry of the complex within the crystals was found to be 2:1 Fab:Fc. The crystals diffracted X-rays to 0.3 nm resolution, and the space group was C2, with cell dimensions a = 16.03 nm, b = 8.19 nm, c = 6.42 nm, beta = 98.3 degrees. We have also determined the sequence of the variable region of the RF-AN light chain, not hitherto reported. This belongs to the V lambda III-a subgroup and is closely related to the germline gene Humlv318, from which it differs in three amino acid residues. This is the first reported crystallized complex between a human autoantibody and its autoantigen.

Effects of glutathione and pH on the oxidation of biomarkers of cellular oxidative stress

Cellular oxidative stress is associated with such pathological conditions as arteriosclerosis, inflammatory diseases and cancer. The oxidation of the biomarkers. 2',7'-dichlorofluorescin (DCFH), 2-deoxyribose, and lipid peroxidation are often used to assess the status of oxidative stress in cells and tissues. Since high levels of reduced glutathione (GSH) and acidic conditions have been associated with diminished chemical lethality, we evaluated the influence of these parameters on the cellular response to oxidative stress. We used a cultured hepatocyte line (ch/ch cells) that is susceptible to oxidative toxicity. A hydroxyl radical-generating system consisting of H2O2, ascorbate and iron produced a pH-dependent lethality, with complete cell killing at pH 7.4 and none at pH 6.8. Lethality correlated with the depletion of intracellular GSH, and with an increase in DNA fragmentation. The influence of GSH and pH was assessed for DCFH and 2-deoxyribose oxidation, and for lipid peroxidation. The oxidation of DCFH and 2-deoxyribose was inhibited by GSH, with about 4-fold greater inhibition efficacy at pH 6.8 than at pH 7.4 [IC50 values (microM GSH) for pH 6.8 and 7.4, respectively: DCFH = 7 and 30; 2-deoxyribose = 125 and 490]. GSH did not affect lipid peroxidation at either pH, even at a high intracellular concentration of 10 mM. We conclude: 1) GSH is not inhibiting DCFH and 2-deoxyribose oxidation by simply quenching reactive oxygen (hydroxyl radical or perferryl oxygen), since GSH did not inhibit lipid peroxidation: 2) the protonated form GSH is more likely to be the inhibitory species rather than GS-, since even in the simple cell-free systems lower pH inhibited biomarker oxidation; and; 3) hydroxyl radical may not be the primary intracellular oxidant of DCFH, since intracellular GSH concentrations are typically 10- to 100-fold higher than the IC50 values for GSH inhibiting reactive oxygen-mediated DCFH oxidation.

Expression of cytochrome P450s and glutathione S-transferases in human esophagus with squamous-cell carcinomas

In order to clarify the expression of cytochrome P450 and glutathione S-transferase in human esophagus, 41 samples of human esophagus with squamous-cell carcinoma were investigated by immunoblot analysis and enzyme assays. Cytochrome P450 1A2/1 was clearly expressed in microsomes, and the amount in samples with tumorous tissue was significantly greater than that in samples without tumourous tissues or in liver; cytochrome P450 2B6 and 3A4/3 were expressed polymorphically. Aryl hydrocarbon hydroxylase activity was detected in microsomes and was greater in samples from smokers than non-smokers. Patients who both smoked and drank alcohol, however, had activity similar to that of patients without these habits. Glutathione S-transferase M1 and A1/2 protein existed polymorphically in cytosol, and glutathione S-transferase P1-1 was detected in all samples. The frequency of expression of the glutathione S-transferase A1/2 protein was greater in patients with M1 protein than in those without; no difference in the expression was seen for glutathione S-transferase P1-1. Neither smoking nor drinking influenced the expression or activity of glutathione S-transferase. Our data support the idea that some carcinogens can be directly activated or inactivated in human esophageal epithelium.

[Effects of different modes for health education on mothers' knowledge of baby feeding]

To study the effects of existing different modes of health education on mothers' knowledge in feeding babies and young children, 414 mothers with their babies aged 0 to 18 months were interviewed with an ad hoc questionnaire in urban and rural areas in Guangdong Province during February to April, 1995. Results revealed that the best source of mothers' nutritional knowledge was derived from a comprehensive mode of health education, the others from mass media and medical care professionals, and the last one from mothers' relatives and friends. Prenatal training course for baby feeding was one of the effective measures in nutritional education, but its effects depended on mothers' occupation and cultural level. Baby-friend hospitals played an important role in improvement of mothers' knowledge level in breast-feeding. It suggests comprehensive education channel, training course for pregnant women, baby-friend hospitals, and so on, all are major means of nutritional education for baby feeding.

Clinicopathologic characteristics and postoperative outcome in Japanese and Chinese patients with thoracic esophageal cancer

We evaluated the clinicopathologic findings and surgical results of 140 patients with thoracic esophageal cancer treated at Shinshu University, Japan (Shinshu group), and compared them with those from 1164 patients treated at Hebei Medical College, China (Hebei group) to determine if the two groups showed any differences. The Shinshu group had significantly higher incidences of elderly patients (>70 years of age), male patients, and tumors located at the lower esophagus (p < 0.01). In the Hebei group, although the depth of tumor invasion was more advanced, the incidence of nodal metastasis was significantly lower (p < 0.01). Operative death and postoperative complications were more frequent in the Shinshu group. Comparison of the postoperative survival curves revealed significantly longer survival of patients with pT2 or pT3 tumor in the Hebei group (p < 0.01), but there were no significant differences between the two groups when the lesions were classified by pTNM stage. This study demonstrated several differences between the patients in the two areas in regard to the clinicopathologic characteristics of thoracic esophageal cancer. The most important characteristic of the esophageal cancer in the Hebei group appears to be the low incidence of nodal metastasis.

p53 mutations in bladder tumors from arylamine-exposed workers

In this study we compared the frequency and pattern of p53 mutations in 34 bladder tumors from people with high-level occupational exposure to arylamines to those in 30 bladder tumors from people without such exposure. No differences were observed for p53 mutations between the two groups. The frequency of mutation was similar at 47% for arylamine-exposed individuals and 53% for unexposed individuals and showed a similar pattern of mutation, with GC to AT transitions accounting for the majority of the mutations in both groups. This finding suggests that arylamine exposure does not leave a mutational "footprint" in the p53 gene. However, compared to other tumors, bladder tumors from both exposed and unexposed individuals had a high frequency of multiple mutations and it is interesting that these mutations were highly concordant. We suggest that one explanation of this pattern of mutations could be from decreased DNA repair fidelity within tumor cells. The frequency of mutation in p53 is closely linked to tumor grade and stage and so may be a late event in the development of bladder tumors.

Positive-ion electrospray-fourier transform ion cyclotron resonance mass spectra of polypeptides and proteins

We have determined the mass spectra of three polypeptides which have been designed as an effective reagent to be used in the diagnosis of a Chinese strain of Hepatitis E Virus (HEV). The spectra were determined by electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometer. These are peptide 30, peptide 33 and peptide 42, where the guanidine amino group of arginine in each polypeptide was protected. The molecular weights were respectively measured as 3575, 4094 and 5390 Dalton, against the molecular weights of bovine serum albumin (66430 Da) and bovine insulin (5732.77 Da).

Extracorporeal circulation for great vessels surgery: a review of 131 cases

A retrospective analysis of 131 cases of major vascular surgery, mainly aneurysms of the ascending and descending aorta, was undertaken to determine whether use of different bypass methods chosen according to location of the individual lesions resulted in improved results. For the 93 cases of ascending aortic aneurysm, the method for cardiac protection was improved by the use of continuous retrograde coronary sinus perfusion with cardioplegic blood. In sixteen cases with dissection involving the aortic arch, deep hypothermic circulatory arrest and continuous retrograde cerebral perfusion through the superior vena cava was employed for brain protection. The safe brain circulation arrest time was thus prolonged to the longest record of 81 minutes. Among the group of 93 cases, there were four operative and four hospital deaths, giving a mortality rate of 8.6% (8/93). For the 34 cases of descending aortic aneurysms, left heart bypass was employed to avoid ischemia of the heart, lungs, brain, and the abdominal organs; the operative mortality rate was 8.8% (3/34). In three cases of interrupted aortic arch, separate upper and lower body perfusion under deep hypothermia with low flow rate perfusion for the upper body provided the necessary conditions for radical surgery. In one patient with Budd-Chiari syndrome, a total corrective surgery was achieved under right heart bypass.

A new nucleophilic ring opening of an activated cyclopropane and a formal synthesis of (+/-)-carbovir

The reaction of bicyclo[3.1.0]hexane 1, possessing a doubly activated cyclopropane ring, with acetic acid and potassium acetate in DMSO proceeded smoothly to give the adduct 2 in good yield. A formal total synthesis of the potent anti-HIV agent (+/-)-carbovir (9) was done by converting 2 into a known precursor 8 in 8 steps via allyl alcohol 7 including the regioselective introduction of a double bond (4 to 5) and attachment of the nucleobase using the Mitsunobu reaction (7 to 8).

[A new technique of esophagogastrostomy above the aortic arch--covering and suspending of the anastomotic area with mediastinal pleura flap]

The postoperative anastomotic leakage is the most severe complication and the principal cause of death after resection of esophageal carcinoma. Especially, anastomosis above the aortic arch is accompanied by high incidence of anastomotic leakage usually with fatal prognosis. The authors improved the conventional method of anastomosis by using a mediastinal pleura flap to cover and suspend the anastomotic area with excellent result. From January of 1990 to April of 1995, 210 patients with esophageal carcinoma were so treated. No anastomotic leakage or stricture developed. Only one patient died of extensive myocardial infarction with an overall mortality of 0.47%. The major merit of this procedure was that the mediastinal pleura flap could cover the area of anastomosis and sustain the dragging force acting on this area, providing a better condition for the anastomosis to heal and thus reducing the possibility of anastomotic leakage.

Clinical application of monoclonal antibody-drug conjugate to immunotargeting chemotherapy of bladder cancer

Monoclonal antibody-drug conjugate was applied in a clinical trial for patients with bladder cancer. Monoclonal antibody HB7A from a mouse splenocyte immunized against human bladder cancer was used as a drug carrier. The anti-cancer drug adriamycin (ADR) was bound to HB7A through a dextran (DEX) bridge to form the conjugate HB7A-DEX-ADR. The in vitro cytotoxic effect of the conjugate on BIU-87 bladder cancer cells was similar to that of free ADR and the mixture of HB7A and ADR. Seven patients with bladder cancer were given HB7A-DEX-ADR intravenously. The immunoperoxidase studies of the resected specimens showed that HB7A was localized specifically in cancer, and histological studies revealed degenerative and necrotic changes of the tumor cells. Patients receiving the conjugate did not experience serious side effects. This study suggests that immunotargeting chemotherapy with HB7A-DEX-ADR is well tolerated by patients and its cytotoxicity on tumor is substantial.

p53 mutations in benign breast tissue

PURPOSE

Patients with benign breast biopsies that exhibit atypical epithelial proliferation or fibroadenoma may be at increased risk for invasive breast cancer. We hypothesized that molecular markers might also be useful to evaluate the malignant potential of nonneoplastic breast tissue.

PATIENTS AND METHODS

Study subjects belonged to a cohort of 6,805 women who underwent biopsy for nonmalignant breast disease at the Mayo Clinic and Rochester-affiliated hospitals between 1967 and 1981. As part of a nested case-control study that compared subjects who developed invasive breast cancer with those who did not, we analyzed a sample of 60 benign breast biopsies for the following markers: HER-2/neu and p53 over-expression by immunohistochemistry, HER-2/neu and PRAD-1 amplification using differential polymerase chain reaction (PCR), and p53 mutation using single-strand conformation analysis (SSCA) and direct DNA sequencing by asymmetric PCR.

RESULTS

None of 60 biopsies showed amplification of HER-2/neu or PRAD-1. Five samples exhibited low-level immunoreactivity to the HER-2/neu protein product. Fourteen samples exhibited focal or diffuse immunoreactivity to the p53 protein. Point mutations in the p53 gene were found in five samples: three of these samples exhibited mutations that altered the amino acid sequence. Only two of five samples with p53 mutation exhibited p53 overexpression. Histologic diagnoses on three samples with nonconservative p53 mutation were, respectively, nonproliferative fibrocystic change, papillomatous hyperplasia, and fibroadenoma.

CONCLUSION

The clinical significance of p53 mutation, p53 overexpression, and low-level HER-2/neu expression in benign breast tissue remains to be determined. Further research will be necessary to evaluate whether these markers could serve as useful adjuncts to histology in evaluation of the malignant potential of benign breast tissue.

Codon bias in actin multigene families and effects on the reconstruction of phylogenetic relationships

Codon usage patterns and phylogenetic relationships in the actin multigene family have been analyzed for three dipteran species--Drosophila melanogaster, Bactrocera dorsalis, and Ceratitis capitata. In certain phylogenetic tree reconstructions, using synonymous distances, some gene relationships are altered due to a homogenization phenomenon. We present evidence to show that this homogenization phenomenon is due to codon usage bias. A survey of the pattern of synonymous codon preferences for 11 actin genes from these three species reveals that five out of the six Drosophila actin genes show high degrees of codon bias as indicated by scaled chi 2 values. In contrast to this, four out of the five actin genes from the other species have low codon bias values. A Monte Carlo contingency test indicates that for those Drosophila actin genes which exhibit codon bias, the patterns of codon usage are different compared to actin genes from the other species. In addition, the genes exhibiting codon bias also appear to have reduced rates of synonymous substitution. The homogenization phenomenon seen in terms of synonymous substitutions is not observed for nonsynonymous changes. Because of this homogenization phenomenon, "trees" constructed based on synonymous substitutions will be affected. These effects can be overt in the case of multigene families, but similar distortions may underlie reconstructions based on single-copy genes which exhibit codon usage bias.

Inhibition of (S)-warfarin metabolism by sulfinpyrazone and its metabolites

Sulfinpyrazone markedly potentiates the anticoagulant effect of warfarin. The increased clotting time is accompanied by a marked decrease in the clearance of (S)-warfarin by virtue of a decrease in the P4502C9-catalyzed formation clearance to its major and inactive metabolite (S)-7-hydroxywarfarin. These data suggested that the mechanism of the drug interaction might be mediated through the inhibition of the catalytic activity of P4502C9 by sulfinpyrazone. However, initial human liver microsomal studies indicated that the in vitro Ki, for inhibition of (S)-7-hydroxywarfarin formation by sulfinpyrazone is at least 25-fold higher than the therapeutic concentration of sulfinpyrazone in vivo. This result implied that other inhibitors probably contribute to the interaction. Kinetic studies conducted on sulfinpyrazone and two major metabolites, sulfinpyrazone sulfide and sulfinpyrazone sulfone, in microsomes prepared from three human livers give mean Ki's of 230 microM, 17 microM, and 73 microM respectively. Because sulfinpyrazone and its sulfide metabolite attain comparable plasma concentrations during the course of therapy, our inhibition results suggest that the sulfide metabolite is likely to be the primary species responsible for the inhibition of P4502C9-catalyzed formation of (S)-7-hydroxywarfarin and the decrease in (S)-warfarin clearance in vivo.

[PCNA expression and AgNORs image analysis as factors in judging the prognosis of lung cancer]

The expression of PCNA and AgNORs count or AgNORs' area in 86 cases of primary lung cancer and 10 cases of inflammatory pseudotumor were studied by S-P immunostaining of monoclonal antibody (PC-10) and image analysis system. The results showed that the proliferating index (PI) of PCNA positive cells was closely related to AgNORs count and AgNORs' area measured. Both were correlated with the histological type, and the TNM status, decreased with the increasing degree of histological differentiation. Survival analysis showed that the PI and the results of AgNORs image analysis in surgical patients who survived over 5 years were significantly lower than those who survived less than 3 years. The results suggest that immunostaining of PCNA and AgNORs image analysis are useful in judging the malignant degree and the prognosis of primary lung cancer.

Engineering a metal binding site within a polytopic membrane protein, the lactose permease of Escherichia coli

Site-directed excimer fluorescence indicates that Glu269 (helix VIII) and His322 (helix X) in the lactose permease of Escherichia coli lie in close proximity [Jung, K., Jung, H., Wu, J., Privé, G.G., & Kaback, H.R. (1993) Biochemistry 32, 12273]. In this study, Glu269 was replaced with His in wild-type permease, leading to the presence of bis-His residues between helices VIII and X. Wild-type and Glu269-->His permease containing a biotin acceptor domain were purified by monomeric avidin affinity chromatography, and binding of Mn2+ was studied by electron paramagnetic resonance (EPR) spectroscopy. The amplitude of the Mn2+ EPR spectrum is reduced by the Glu269-->His mutant, while no change is observed in the presence of wild-type permease. The Glu269-->His mutant contains a single binding site for Mn2+ with a KD of about 43 microM, and Mn2+ binding is pH dependent with no binding at pH 5.0, stoichiometric binding at pH 7.5, and a midpoint at about pH 6.3. The results confirm the conclusion that helices VIII and X are closely opposed in the tertiary structure of lac permease and provide a novel approach for studying helix proximity, as well as solvent accessibility, in polytopic membrane proteins.

Characterization of a progesterone-binding, three-domain antibody fragment (VH/K) expressed in Escherichia coli

The heavy chain variable region (VH) and the kappa light chain of the anti-progesterone monoclonal antibody (mAb) DB3, have been expressed as a single-chain three-domain polypeptide, designated VH/K, and secreted into the periplasmic space of Escherichia coli (E. coli). The linker sequence was derived from the VH-CH1 elbow region. The C kappa domain provides a sensitive detection tail for Western blotting and enzyme-linked immunosorbent assay (ELISA). Periplasmic extracts of transformed E. coli contained material that bound progesterone and related steroids with similar specificity and affinity to DB3, and displayed the DB3 idiotype and kappa chain epitopes. Reference to the crystal structure of DB3 suggests that all the characteristics of the combining site interaction with steroids are retained in the bacterially expressed material. Western blotting demonstrated material with a molecular weight equivalent to three domains after reduction, but six domains in the unreduced state, suggesting that the VH/K polypeptide is assembled in the periplasm as a disulphide-bridged dimer. The VH/K construct provides a novel route to expression of antibody combining sites in E. coli for antibody engineering.

The actin gene family in the oriental fruit fly Bactrocera dorsalis. Muscle specific actins

The actin protein is a critical protein in eukaryotic cells. Four actin genes, constituting what appear to be a set of muscle specific actin genes, have been isolated from the genome of the oriental fruit fly Bactrocera dorsalis. DNA sequences have been determined for the coding as well as 3' and 5' flanking regions for each of these genes. These genes have also been characterized in terms of RNA expression patterns, and comparisons have been made to actin genes from other species. Consistent with other actins, there is a high degree of amino acid sequence conservation in the coding regions of these genes. However, even within the coding regions codon usage patterns in the oriental fruit fly are quite different from some other well characterized species. In addition, the DNA sequences in the intermediate 3' and 5' flanking regions exhibit virtually no detectable sequence homology both within and between species. In terms of introns, three of the four actin genes from the oriental fruit fly described here have a single intervening sequence. Two of these genes share the same intron position with the two muscle specific actin genes act79B and act88F from Drosophila melanogaster and with one muscle specific actin gene CcA1 from the Mediterranean fruit fly, Ceratitis capitata. Another gene from the oriental fruit fly shares the same intron position as the muscle specific actin gene act57B from D. melanogaster. Such conservation of intron positioning between species is highly unusual among previously characterized actin genes. Using unique sequences found in the 3' untranslated regions, gene specific probes have also been constructed. These have been used to detect the expression patterns of individual genes in a temporal and spatial manner. Each of the four genes examined here show differential patterns of expression. The patterns indicate that all four genes are most likely to encode muscle specific actins.

Expression and export in Escherichia coli of fusion proteins containing carboxy-terminally located honeybee prepromelittin

The aim of this work was to express a eukaryotic pre-protein in Escherichia coli so that it could be obtained intact, without cleavage, by bacterial leader peptidase. To this end, cDNA coding for honeybee prepromelittin was ligated to the 3' end of genes coding for truncated forms of either Protein A or beta-galactosidase (beta-Gal) under the control of inducible promoters, with an oligonucleotide coding for the Factor Xa cleavage site at the junction between the two proteins. The Protein A fusion was expressed in good yield, and about 80% of it formed inclusion bodies. The prepromelittin section of the Protein A fusion caused some export of the intact fusion protein to the growth medium. The prepromelittin beta-Gal fusion was expressed in low yield and became associated with the E. coli cytoplasmic membrane. Its expression was toxic to E. coli. Thus, the synthesis of a full-length eukaryotic pre-protein in E. coli is best achieved when the fusion protein forms inclusion bodies.

Oligodendroglial signal transduction systems are developmentally regulated

Studies from several laboratories indicate that oligodendroglia exhibit signal transduction systems that can be activated by classical neurotransmitters. Previous studies from this laboratory indicate that oligodendroglia express neuroligand receptors linked to the regulation of Ca(2+)i. Experiments presented in this article were designed to determine if developmental processes that influence the ability of oligodendroglia to respond to neuroligands with an increase in Ca2+i proceed either in vitro or in vivo. Findings support the view that developmental processes markedly affected the sensitivity of these cells to both purinergic and cholinergic receptor agonists, whereas their responsiveness to either histamine or bradykinin appeared relatively stable over time. Approximately 90 and 75% of oligodendroglia responded to ATP or carbachol, respectively, after 4 days in vitro, whereas < 10% of these cells responded to either of these neuroligands after 8 days in vitro. The decrease in the percentage of oligodendroglia responding to ATP, but not carbachol, could be prevented by including dibutyryl cyclic AMP in the culture medium during the final 4 days in vitro. However, once the loss in responsiveness to ATP had occurred, it could not be reversed by exposure to dibutyryl cyclic AMP. Developmental changes in the ATP sensitivity of oligodendroglia occurred in cells expressing galactocerebroside and myelin basic protein. The neuroligand sensitivity of oligodendroglia isolated from either neonatal, 2-, 3-, or 5-week-old spinal cord was examined to determine if developmental changes in oligodendroglial Ca2+ regulation occurred in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Two novel human serine/threonine kinases with homologies to the cell cycle regulating Xenopus MO15, and NIMA kinases: cloning and characterization of their expression pattern

Using polymerase chain reaction (PCR)-based methods, we have isolated cDNA clones of two new members of serine/threonine kinases, STK1 and STK2, from a cDNA library constructed from the BT-20 human breast cancer cell line. STK1 is transcribed as a 1.4 kilobase (kb) mRNA encoding for a protein of 346 amino acids. Based on amino acid sequence analysis, STK1 is 86% identical to the Xenopus p40mo15, a cdc2-related serine/threonine kinase recently found to be the activating kinase for p34cdc2 and p33cdk2. Thus, STK1 is most likely the human homologue of MO15. An alternatively spliced STK1 message expressed variably in cell lines and in primary carcinomas generates a predicted 58 amino acid protein that lacks the kinase domain. STK2 is transcribed into a 4.0 kb mRNA encoding for an 841 residue protein which exhibits 50% identity in the kinase domain with the mouse nek1 gene product, the relative of the fungal G2-M regulator, nimA. STK1 and STK2 display a variable pattern of expression among a series of primary carcinomas as well as cancer cell lines. Both STK1 and STK2 were expressed at the highest levels in the heart but were also detected in all other organs tested. In embryonal tissues, lower levels of expression were noted. Using cell cycle inhibitors, we have shown that both STK1 and STK2 mRNA levels remain relatively invariant through the cell cycle. Chromosomal assignment has localized STK1 on chromosome 2pcen-2p15, a region implicated in hereditary non-polyposis colorectal carcinoma, and STK2 on chromosome 3p21.1, a region frequently showing chromosomal alterations in renal cells carcinomas.

Genetic alterations in the p53 gene in the blast crisis of chronic myelogenous leukemia: analysis by polymerase chain reaction based techniques

Rearrangements of the c-abl protooncogene and the bcr-gene are found in > 90% of patients in chronic phase of chronic myelogenous leukemia (CML). The molecular events leading to blast crisis, however, have not been well characterized. Gross alterations of the p53 gene have been detected in 30% of patients with blast crisis. Since point mutations in the p53 gene appear to be important in the process of transformation in many epithelial tumors, we looked for these mutations in the critical regions of the p53 gene (exons 4, 5, 6, 7, and 8). We used the polymerase chain reaction (PCR), direct sequencing, differential PCR, and single strand conformation polymorphism (SSCP) analysis to detect mutations of the p53 gene in samples from 21 patients with CML blast crisis. Two of 21 patients exhibited an intragenic deletion or rearrangement in p53. In addition, these patients were homozygous for the mutant p53 allele. No mutations were found in the p53 gene of the remaining 19 patients. However, sequencing of the CML blast crisis cell line, K562, revealed an insertion of a C at base position 956 within the fifth exon, causing a frame shift mutation and an early translational stop at codon 148. We conclude that, in contrast to solid tumors, mutations in exons 4-8 of p53 are not frequently seen in primary samples from CML blast crisis. However, deletions and/or rearrangements within the p53 gene do occur and may contribute to the progression from chronic phase to blast crisis in a limited number of patients with CML.

Specificity of factor Xa in the cleavage of fusion proteins

The precursor protein honey bee prepromelittin has been expressed as a fusion protein in Escherichia coli joined to the C-terminus of a truncated form of the bacteriophage gene 10 protein via an engineered recognition sequence for Factor Xa. Factor Xa was found to cleave poorly at the engineered site, giving a low yield of the required prepromelittin. In contrast, cleavage on the C-terminal side of the sequence VLGR at residue 67 in the gene 10 sequence proceeded in high yield. Factor Xa may be inhibited by adjacent hydrophobic sequences on the C-terminal side of a potential cleavage site.

Differential polymerase chain reaction in the analysis of gene dosage

Abnormalities of gene dosage are important in human disease. We have developed the differential polymerase chain reaction (PCR) to detect gene amplification and deletion in small amounts of tissues whose DNA may be degraded. The current utility of differential PCR required optimization of DNA isolation procedures, of primer selection approaches, and of PCR conditions. From this experience, we have formulated a theoretical framework for the technique, and describe appropriate applications and potential improvements based on emerging PCR technologies. Special emphasis is placed on the analysis of formalin fixed and paraffin embedded, archived specimens.

Changes in levels of pancreatic endoplasmic reticulum proteins that function in translocation and maturation of secretory proteins in response to cholecystokinin

Two pathways operate to target newly-synthesised proteins to the endoplasmic reticulum. In one, the signal recognition particle attaches to the signal sequences of nascent chains on ribosomes and slows or stops translation until contact is made with the docking protein at the membrane. The second operates via molecular chaperons. The pathways converge at the level of a 43 kDa signal binding protein integrated into the membrane, where translocation through a proteinaceous pore is initiated. In the lumen, proteins fold and disulphide formation is catalysed by the enzyme protein disulphide isomerase. The heavy chain binding protein may attach to unassembled or unfolded proteins and prevent their exit from the ER to the Golgi. Cholecystokinin (CCK) treatment increases the biosynthesis and secretion of pancreatic proteins, increases the levels of PDI and the 43 kDa binding protein, and reduces levels of BiP. These proteins may be possible targets for genetic manipulation to improve processing of heterologous proteins from cultured mammalian cells.