Alpha-interferon structure and natural killer cell stimulatory activity

Expression vectors for human alpha-interferon (Hu-IFN-alpha) J1, a site-specific mutant [Ser116]Hu-IFN-alpha J1, and Hu-IFN-alpha J/C or Hu-IFN-alpha C/J hybrids were constructed and expressed in Escherichia coli. These interferons and others were purified by immunoaffinity chromatography with a monoclonal antibody against human alpha-interferon. Their antiviral activity and ability to stimulate natural killer cell activity were determined in comparison to several other human interferons. These results provide some insight into structure-activity relationships for stimulating natural killer cells and confirm our previous conclusions that antiviral activity cannot be used to predict other activities for an individual IFN-alpha species. The observations suggest that the tertiary structure rather than any specific linear sequence of amino acids regulates the ability of the interferons to stimulate natural killer cell activity.

Computational techniques for vertex partitioning of graphs

A powerful vertex-partitioning algorithm is developed and applied for vertex partitioning of graphs of chemical and spectroscopic interest. The codes developed on the basis of these algorithms are tested and compared for performance with other methods based on the Morgan algorithm and the principal eigenvector algorithm based on the Givens-Householder method. The newly developed algorithm and codes appear to be more powerful than the Morgan and the principal eigenvector algorithms for vertex partitioning of graphs.

[Changes in the levels of human platelet membrane glycoproteins in patients with a new-type defect of platelet aggregation]

Labeled avidin-biotin (LAB)-enzyme linked immunosorbent assay (ELISA) for quantitative measurement of the levels of human platelet membrane glycoproteins (GPs) Ib, IIb and IIIa was developed by using a group of murine monoclonal antibodies raised against human platelet membrane GPs. The contents of the GPs Ib, IIb and IIIa in patients with a new-type defect of platelet aggregation were detected and found to be in normal range. However, the amounts of GPs IIb and IIIa before washing in patients were significantly decreased in these patients when compared with those in controls (P less than 0.01), while after washing, normal levels could be obtained. The results reported have support the hypothesis that the pathogenesis of this defect in platelet aggregation seems not to be associated with the abnormality of the levels of GPs, but is a result of abnormal factor existing in the plasma. Further investigation on the properties of the factor is in progress.

Early development of brainstem auditory evoked potentials in Down's syndrome

Early development of brainstem auditory pathway was studied in 14 children with Down's syndrome (age range from 1 month to 3 years). The brainstem auditory evoked potentials (BAEP) during infancy was characterized by elevated threshold and poorly differentiated wave I. All children within 2 years had elevated threshold in one or both ears, suggesting a high incidence of peripheral hearing deficits. Follow-up tests showed that as age increased up to 3 years the elevated threshold gradually decreased and the differentiation of wave I improved. The I-V interpeak interval was slightly shorter and the amplitude of wave V was smaller than the normal controls, which existed continuously during follow-up studies. Our findings suggest that the development of peripheral hearing is delayed, although persistent hearing deficits cannot be excluded, and the functioning and development of the brainstem auditory pathway may also be abnormal in Down's syndrome children.

Long-term impairments of brain and auditory functions of children recovered from purulent meningitis

Sixty children who had recovered from purulent meningitis one to six years earlier were investigated for long-term impairment of brain and auditory function, using brainstem auditory evoked potentials(BAEP) and developmental screening tests. Neurological and/or audiological BAEP abnormalities were found in 23 per cent of the children: 15 per cent had mild brainstem impairment and 12 per cent had hearing dysfunction. Developmental screening tests were administered to 46 children, of whom 61 per cent had normal, 22 per cent questionable and 17 per cent abnormal results. The results of the BAEP significantly correlated with those of the developmental screening tests, suggesting that the neuropsychological development of children with BAEP abnormalities was significantly delayed compared with that of children without BAEP abnormalities. The characteristic finding in a neurologically abnormal BAEP was slightly depressed amplitude of wave V, and the authors suggest that this is the most sensitive BAEP measure for the assessment of brainstem function in children recovered from meningitis.

Increasing flap survival: a new method

A new method of continuous irrigation beneath a flap with special irrigation was designed to attempt to improve flap survival in 42 animals. In each animal experimental and control flaps were symmetrically designed using two flanks or limbs (total number of flaps, 154). The flap length survival in the 77 experimental flaps ranged from 18 to 88% greater than that in the control flaps. Bacterial cultures of the secretions from all flaps suggested that this method has a practical value in preventing and controlling the infections that would result in flap necrosis.

Regional left ventricular ejection fraction with single crystal gammacamera and gated equilibrium technique: repeatability and inter-observer variability

Regional left ventricular ejection fraction calculated by means of gated blood pool scintigraphy was compared with that obtained from contrast ventriculography in a group of 20 patients, submitted to both procedures within a month. To evaluate repeatability both at rest and during stress, a second scintigraphic study was carried out after three weeks, with no change in drug regimen. Inter-observer variability was assessed in a randomly selected subgroup of 16 patients, in whom a computation was repeated by a second operator. Comparison of scintigraphic results showed a satisfactory agreement, and measurement agreement for global left ventricular ejection fraction was very good. As regards interobserver variability, each of the three myocardial segments examined (septal, lateral and infero-apical) showed good agreement. As regards repeatability, global left ventricular ejection fraction, proved readily reproducible both for rest and stress studies, with relatively small differences in observed values. Regional ejection fraction, on the other hand, had a high variability, especially during stress. It is suggested that for regional ejection fraction evaluation, reproducibility studies should be performed in order to better correlate result changes to clinical outcome after medical or surgical therapy.

Spectroscopy and fluorescence quenching of tyrosine in lima bean trypsin/chymotrypsin inhibitor and model peptides

The effects of citrate ion concentration and pH on the optical spectra and fluorescence decay have been measured for several tyrosine model compounds and lima bean trypsin/chymotrypsin inhibitor, a protein containing one tyrosine at position 69 and seven disulfides but no tryptophan, in order to determine the location and environment of Tyr 69. Tyrosine in the protein is protected from citrate collisional quenching, as indicated by the dynamic quenching constant 9 to 15 times smaller than those for the model peptides. Static quenching remains, with a Stern-Volmer constant of about 1.0 M-1, somewhat smaller than those of L-tyrosine, tyrosine-glutamate, and leucine-tyrosine-leucine. The elevated pKa of Tyr 69, greater than or equal to 11.6, also indicates protein protection from solvent ions. Though Coulomb repulsion of the Glu 70/citrate pair may play a role in the shielding of Tyr 69 from citrate, our measurements indicate that steric effects of the protein structure are more important. Tyrosinate emission in the protein at neutral pH is minimal.

Effects of sodium salicylate on the febrile response and increased levels of cyclic AMP in cerebrospinal fluid during endogenous pyrogen-induced fever in rabbits

To further evaluate the causality between endogenous pyrogen (EP)-induced fever and cyclic adenosine-3',5'-monophosphate (cyclic AMP) level, the effects of sodium salicylate (SS) on the febrile response and increased levels of cyclic AMP in both cerebrospinal fluid (c.s.f.) and plasma during EP-induced fever in rabbits were observed. The results suggest that cyclic AMP is probably involved in the central mediation of EP-induced fever and that increased concentration of cyclic AMP in c.s.f. associated with EP-induced fever is not the result of temperature elevation but appears to be caused by the increased synthesis in the central nervous system. In addition it is confirmed that blood is impossibly a contributory source of increased cyclic AMP in c.s.f. during EP fever, and that SS may act subsequent to the increase in cyclic AMP.

Study on the mechanism of interferon action (XI)--Effect of pppA2'p5'A on the level of cAMP and cGMP in macrophages

In this paper, the increase of cellular cAMP and cGMP levels in macrophages induced by ppA2'p5' A2'p5'A (briefly 2'-5'P3A3) is first reported. The optimal concentration of 2'-5' P3A3 for the elevation of cellular cGMP to the highest level is 10(-7)-10(-6) mol/L, while that for cAMP is 10(-7) mol/L. The time for cGMP to reach its peak value is 15 min and that for cAMP is 2 h, when the cells are treated with 2'-5' P3A3 at 10(-7) mol/L, which is the optimal concentration for developing biological effect of macrophages (phagocytosis). These results suggest that cGMP and cAMP may be related to, or may be the mediators for, 2'-5'P3A3 action.

Mechanism of interferon action. X--Antagonistic effect of ATP on pppA2'p5'A2'p5'A receptor

pppA2'p5'A2'p5'A (2'-5'P3A3) receptor may be the first one in the oligonucleotide field. But ATP can compete with 2'-5'P3A3 for the receptor. This raises a question whether this is an ATP receptor. If not, what is the role of ATP for this receptor? Data available in this article show that ATP can bind to macrophages with saturability and reversibility. So ATP appears to be also a ligand of the receptor for 2'-5'P3A3. But the binding of ATP did not develop phagocytic effect as mentioned before. Moreover, ATP inhibited the enhancement of phagocytosis of macrophages by 2'-5'P3A3 when it acted together with 2'-5'P3A3 on macrophages at the same time. It is concluded that ATP is an antagonist of 2'-5'P3A3 receptor. When macrophages were treated with ATP prior to 2'-5'P3A3 and the binding sites for 2'-5'P3A3 were first occupied by ATP, both the binding ability and the binding sites for 2'-5'P3A3 were first occupied by ATP, both the binding ability and the biological effect of 2'-5'P3A3 were all markedly blocked. The above data convincingly show that the action of 2'-5'P3A3 is definitely mediated through its receptor.

Expression of a pseudogene for interferon-alpha L

The human leukocyte interferon-alpha L (IFN-alpha L) appears to be a pseudogene because it contains a termination codon in the DNA coding for the precursor peptide (signal peptide), but the remainder of the gene codes for an interferon protein of normal length. To determine if this gene codes for an active interferon molecule, an expression plasmid was constructed for IFN-alpha L that was produced in Escherichia coli. The IFN-alpha L is active on human and bovine cells, and exhibits a trace of activity on mouse cells.

The reaction mechanism of N-benzoylimidazole with ribonucleotides

The reaction of uridine 3'-phosphate with benzoylimidazole in the absence and presence of a strong base was followed up by 31P and 1H nmr as well as paper electrophoresis. Possible reaction courses were proposed, the reaction rate constants were calculated and the reaction mechanism was discussed. It is possible to selectively acylate ribonucleotides with benzoylimidazole by appropriate choice of the base used.

Fluorescence polarization decay of tyrosine in lima bean trypsin inhibitor

The fluorescence of lima bean trypsin inhibitor is due to a single tyrosine residue at position 69. The lifetime of this tyrosine fluorescence is 620 +/- 50 ps (mean +/- SD) and is little affected by addition of 0.88 M citrate, an efficient quencher of tyrosine fluorescence. The steady-state emission intensity is also only weakly reduced by the quencher. The tyrosine is thus not accessible to the citrate and is probably located in the interior of the protein. The high pK of the tyrosine supports this conclusion. The fluorescence anisotropy decay of the inhibitor's tyrosine can be fitted to a double exponential form, with time constants of about 40 ps and greater than or equal to 3 ns. The anisotropy at time zero is 0.19 +/- 0.015 (mean +/- SD), the same as for N-acetyl-L-tyrosinamide in viscous glycerol solution. The nanosecond component of the decay is consistent with rotation of the entire protein molecule. The 40-ps component demonstrates that the tyrosine has considerable freedom to move independently of the protein as a whole. This rotational correlation time is approximately what is observed for free tyrosine in aqueous solution. Since the polypeptide chain near tyrosine-69 is anchored by several disulfide bonds, the data argue that this interior portion of the protein consists of a rigid, immobile backbone embedded in fluid, mobile amino acid side chains.

[Preparation and preliminary identification of the monoclonal antibody against esophageal carcinoma]

A series of monoclonal antibody against esophageal carcinoma was prepared by ECa109 cells immunizing Balb/c mice. Hybrids secreting antibodies reacting to ECa109 were isolated and further cloned. One monoclonal antibody, 4C3, reacted only to an esophageal cancer cell line, gastric cancer and hepatocellular carcinoma cell lines. Purified 4C3 was used in ELISA test to detect tumor cells in the esophageal epithelial cells obtained by friction balloon. The result showed that the concordance rate to the result of balloon cytosmear was 62.4% (73/117). Patients, diagnosed cytologically as dyskaryosis, were often positive in ELISA test. It is proposed that 4C3 be useful in detecting pre-cancerous lesions.

The role of metaphosphate in the activation of the nucleotide by TPS and DCC in the oligonucleotide synthesis

The course of the activation of 3'-acetylthymidine 5'-phosphate by TPS and DCC were followed up by 31P FT nmr. The fact that the "metaphosphate" (delta-5.1) first becomes detectable only at later stage of the activation and does coexist with pyrophosphate and triphosphate suggests that the pyridinium derivative of "metaphosphate" is most probably not directly formed from the hypothetical mixed anhydride or active "pseudourea" right at the beginning of the reaction of pdTac with TPS or DCC, but rather formed at later stage of the activation reaction from the degradation of the pyro- and triphosphates by the activating agent. The mixed anhydride or the active "pseudourea" is most possibly the active key intermediate.

Mechanism of interferon action--structural requirement of ligand and cellular specificity

We had reported the existence of 2'-5'P3A3 receptor on the peritoneal macrophages from Wistar rat. In this paper data are given to demonstrate that the ligand, for binding with 2'-5'P3A3 receptor and enhancing the phagocytosis of macrophages, must have a three-phosphate radical on its 5'-terminus and at least three adenylate residues in 2'-5'oligoadenylate. (3H)-2'-5'P3A3 can also bind on macrophages from other animals; and the binding of (3H)-2'-5'P3A3 on Hepatoma cell line 7402 is lower than that on macrophages; whereas it is very low (binding ratio less than 1%) on erythrocytes (from rabbit, rat and mouse) or human embryo lung fibroblast cells. The binding conditions of the ligand with 2'-5'P3A3 receptor have also been investigated.

Mechanism of interferon action--the discovery of the pppA2'p5'A2'p5'A receptor

In this paper it is demonstrated that (3H)2'-5'P3A3 can bind to the peritoneal macrophages from Wistar rat. This binding is strongly inhibited by cold 2'-5'P3A3, while the inhibiting capacity of 2'-5'P3I3 and 2'-5'A3 is very small, showing that this binding is highly specific. And the binding of (3H)2'-5'P3A3 is reversible, saturable and with high affinity. A Scatchard analysis of the binding data gives a linear plot, an apparent dissociation constant (Kd) about 1.3 X 10(-7) M and binding sites per cell about 2.1 X 10(7). The above evidence shows the existence of the 2'-5'P3A3 receptor, a fact which, to our knowledge, has not been reported before.