Solution structure of the aminofluorene-intercalated conformer of the syn [AF]-C8-dG adduct opposite a--2 deletion site in the NarI hot spot sequence context

This paper addresses structural issues related to the capacity of aminofluorene [AF] for frameshift mutations of the -2 type on C8 covalent adduct formation at the G3 site in the d(C-G1-G2-C-G3-C-C) NarI hot spot sequence. This problem has been approached from a combined NMR and relaxation matrix analysis computational structural study of the [AF]dG adduct in the d(C-G-G-C-[AF]G-C-C).d(G-G-C-C-G) sequence context at the 12/10-mer adduct level (designated [AF]dG.del(-2) 12/10-mer). The proton spectra of this system are of exceptional quality and are consistent with the formation of an AF-intercalated conformer with the modified guanine in a syn alignment displaced along with the 5'-flanking cytosine residue into the major groove. The solution structure has been determined by initially incorporating intramolecular and intermolecular proton-proton distances defined by lower and upper bound deduced from NOESY spectra as restraints in molecular mechanics computations in torsion angle space and subsequently refined through restrainted molecular dynamics calculations based on a NOE distance and intensity refinement protocol. Strikingly, the [AF]dG.del(-2) 12/10-mer duplex adopts only one of two potential AF-intercalation alignments for the [AF]dG adduct opposite the -2 deletion site in the NarI sequence context with the extrusion of the dC-[AF]dG step favored completely over extrusion of the [AF]dG-dC step at the lesion site. This polarity establishes that the structural perturbation extends 5' rather than 3' to the [AF]dG lesion site in the adduct duplex. This structure of the [AF]dG adduct opposite a -2 deletion site shows distinct differences with conclusions reported on the alignment of the related acetylaminofluorene [AAF]dG adduct opposite a -2 deletion site in the identical NarI sequence context [Milhe, C., Fuchs, R. P. P., and Lefevre, J. F. (1996) Eur. J. Biochem. 235, 120-127]. In that study, qualitative NMR data without computational analysis were employed to conclude that the extrusion at the lesion site occurs at the [AAF]dG-dC step for the AAF-intercalated conformer of the adduct duplex. The structure of the [AF]dG adduct opposite a -2 deletion site determined in our group provides molecular insights into the architecture of extended slipped mutagenic intermediates involving aromatic amine intercalation and base-displaced syn modified guanines in AF and, by analogy, AAF-induced mutagenesis in the NarI hot spot sequence context.

Cholinergic control of nerve growth factor in adult rats: evidence from cortical cholinergic deafferentation and chronic drug treatment

It is well documented that nerve growth factor (NGF) plays an important role in maintaining functions of cholinergic basal forebrain neurons. In the present study, we tested the hypothesis that cholinergic activity controls NGF levels in cholinoceptive neurons of the cerebral cortex and hippocampus. To address that question, we used both cholinergic deafferentation of cerebral cortex and hippocampus by cholinergic immunolesion with 192IgG-saporin and chronic pharmacological treatment of sham-treated and immunolesioned rats with the cholinergic agonist pilocarpine and the cholinergic antagonist scopolamine. We observed an increase in NGF protein levels in the cortex and hippocampus after cholinergic immunolesions and also after muscarinic receptor blockade by chronic intracerebroventricular scopolamine infusion in sham-treated rats after 2 weeks. There was no further increase in the accumulation of NGF after scopolamine treatment of immunolesioned rats. Chronic infusion of pilocarpine had no effect on cortical and hippocampal NGF protein levels in sham-treated rats. In rats with cholinergic immunolesions, however, pilocarpine did prevent the lesion-induced accumulation of NGF. There was no effect of cholinergic lesion and drug treatment on cortical or hippocampal NGF mRNA levels, consistent with the importance of NGF retrograde transport as opposed to its de novo synthesis. This study provides strong evidence for the hypothesis that there is cholinergic control of cortical and hippocampal NGF protein but not mRNA levels in adult rats.

[The long-term therapeutic results of chemotherapy combined with radiotherapy in advanced nasopharyngeal carcinoma]

OBJECTIVE

To evaluate the effect of chemothrapy combined with radiotherapy in advanced nasopharyngeal carcinoma (NPC).

METHODS

From Dec. 1989 to Dec. 1990, 76 patients with locally advanced NPC (stage III or IV) were treated with 3 cycles of cisplatin [PDD, 20 mg.(m2)-1.day-1, i.v. on days 1-5] and 5-Fluorouracil (5-Fu, 700 mg.(m2)-1.day-1 by continuous i.v. infusion on days 1-5 followed shortly thereafter by radiotherapy. Eighty-six patients treated with radiotherapy alone in 1989 were taken as control. The methods and time/dose schedule of radiotherapy were similar in the two groups.

RESULTS

The response rate to chemotherapy was 89.3% [complete response (CR) 18.4%]. The overall 5-year survival was 48.7% in the combined treatment group and 33.6% in the control group (P > 0.05). The 5-year survival in the combined treatment group was 44.1% and 39.5%, in patients with T2N3 and T2-4N3 and 21.6% and 20.4% in the control group, respectively (P < 0.05).

CONCLUSION

This prospective study demonstrates that PDD/5-Fu chemotherapy followed by radiotherapy can improve 5-year survival in patients with T2-4N3 nasopharyngeal carcinoma.

[Sudden deafness: stepwise regression analysis on the correlation factors with prognosis]

To further investigate the correlation factors of the prognosis and therapeutic efficiency of sudden deafness, 83 cases (91 ears) from 1993. 1 to 1996. 4 were studied with stepwise regression analysis. The results showed that the prognosis is correlate with the age, the hearing threshold levels of both speech and high frequencies, and the types of the audiometric curve, but not with the illness duration, sex, vertigo, ipsi or bilateral, recurrence, virus infection, cardiac or cerebral vascular diseases, and the medicine or the duration of the treatment. By comparing the results obtained from different statistical analysis, it was suggested that the unification of the criteria of the diagnosis and the therapeutic efficiency as well as the application of the multiple factors regression analysis are essential for the research on sudden deafness.

[The inhibitory effect of hydroprednisolone on tumor necrosis factor in rabbits' temporomandibular joint disturbance syndrome]

In order to study the mechanism of hydroprednisolone for temporomandibular joint disturbance syndrome (TMJDS), 12 white rabbits were injected TNF into the rabbits' right TMJDS for 2 to 3 times, 90,000 u each time, then another drug, 2 mg hydroprednisolone, was injected into these TMJDS again. The rabbits were killed after 8 to 18 days and the TMJDS were examined by microscope. We found the articular tissues only destroyed slightly and sometimes the cartilages were nearly normal. So, the study suggested that hydroprednisolone can reduce the destruction of TNF on rabbit's TMJ obviously. This may be the cause why hydroprednisolone is useful to TMJDS.

[Prostacyclin participates in regulation of hypoxic and high CO2 cerebrovascular tension]

By using prostacyclin synthetase inhibitor-indomethacin, the effects of prostacyclin in the presence of endothelial cell on hypoxia- and high CO2-induced vasodilatation were studied in newborn calf basilar artery strips. The results showed that indomethacin had no effects on cerebrovascular tension, but attenuated the hypoxia- and high CO2-induced vasodilatation. After destroying the endothelial cell, the cerebral vascular dilatation was decreased, and indomethacin had no obvious effect on the vascular tension. These results suggest that both prostacyclin and endothelial cell are involved in hypoxia- and high CO2-induced vasodilatation and the former is derived from endothelial cell.

[The application of transmeatal exploratory tympanotomy]

Transmeatal exploratory tympanotomy has been used traditionally for the surgical treatment of conductive deafness. With 8 cases of the middle and inner ear diseases diagnosed and surgical managed successfully with this approach, the extended applications of this procedure were illustrated, which included: 1. conductive deafness with cause undetermined, 2. post traumatic conductive deafness with intact tympanic membrane, 3. suspected primary space occupying lesion of tympanum. 4. perilymphatic fistula, and 5. cerebrospinal fluid otorrhea. The key consideration and advantage of this approach were also discussed in this paper.

[Chemical constituents of Strychnos nitida G. Don]

Six compounds were isolated from the root and stem of Strychnos nitida for the first time. On the basis of chemical properties and spectral data, the compounds were identified as beta-sitosterol, strychnine, brucine, cantieyine, lignoceric acid and palmitic acid.

[Preliminary studies on the rabbit oviductin "DPF-1"]

Anti-rabbit 64 kDa oviductin (named Development Promoting Factor-1, DPF-1) antibody could inhibit totally the early development of mouse fertilised eggs cultured in the conditioned medium derived from the rabbit oviduct mucosa epithelial cells, revealed that DPF-1 synthesized and secreted from rabbit oviduct mucosa has a function to overcome the developmental block of early mouse embryos. It seems that DPF-1 consists of a group of polypeptide isoforms, since its isoelectric points are ranging from 7.2 to 8.1 (Fig. 3). The synthesis and secretion of DPF-1 was not dependent on either 17 beta-estradiol or progesterone (Fig. 7), it can pass through zona pellucida easily and associate tightly with the early embryonic cell membrane (Fig. 6). By using Western blotting method, we found that DPF-1 was not appeared in the tissues of liver, heart, lung, spleen, uterus, ovary, small intestine, skeleton muscle and brain, but in that of oviduct (Fig. 4): some DPF-1 homologous molecules were also revealed in the oviduct tissues of mouse and golden hamster, their apparent molecular weights were 32 kDa, 72 kDa in mouse, and 49 kDa, 68 kDa in golden hamster (Fig. 5). Results obtained from the in vivo anti-fertility experiment, namely to analyse the anti-fertility effect in adult female mice after active immunization with DPF-1, showed that the fertility decreased significantly as compared to those of controls (p < 0.01) (Table 1). DPF-1 and its in vivo "loss of function" evidence we obtained will encourage us to study the mechanism of DPF-1 in overcoming the developmental block of early embryos, and its role in transition from maternal to embryonic control of early development.

Effectiveness of 3TC in HIV clinical trials may be due in part to the M184V substitution in 3TC-resistant HIV-1 reverse transcriptase

OBJECTIVE

To measure the extent of HIV resistance to (-)-2',3'-dideoxy-3'-thiacytidine (3TC, lamivudine) within the context of monotherapy and to assess the presence of the M184V substitution in the case of 3TC-resistant viruses. Whether the success of 3TC in clinical trials could be due, in part, to an increase in the fidelity of HIV reverse transcriptase conferred by the M184V substitution was also considered.

METHODS

Two separate monotherapy studies were evaluated, one involving adults with CD4 counts > or = 300 x 10(6)/l, and the second involving children, some of whom had received antiretroviral treatment previously, while others were drug naive. Peripheral blood and plasma samples were collected regularly, and HIV isolation and determinations of drug median inhibitory concentration values were performed using umbilical cord mononuclear cells as targets. Amplification of the 184 mutation was performed by the polymerase chain reaction, using specific primer pairs. Fidelity determinations using purified, recombinant HIV reverse transcriptase derived from either wild-type virus or viruses that contained the 184V substitution were performed.

RESULTS

Phenotypic resistance was detected in almost all subjects at times ranging from 8-20 weeks after initiation of therapy. The 184V substitution was usually detected prior to the occurrence of phenotypic resistance to 3TC. Fidelity determinations revealed that the 184V substitution conferred an approximately 5- to 10-fold increase in HIV reverse transcriptase fidelity. In addition, titres of patient sera tested for their ability to neutralize autologous sequential viral isolates were stabilized in patients receiving 3TC therapy as opposed to other drugs.

CONCLUSIONS

Resistance to 3TC developed in virtually all subjects treated with this drug, and was associated with the appearance of an M184V mutation in HIV reverse transcriptase. The clinical benefit of 3TC therapy may be attributable in part to selection of viruses that are less able to replicate and mutate than the wild types.

[Cloning and identification of recombinant cDNA to a rabbit oviductin "DPF-1"]

A recombinant cDNA library to polyA + RNA isolated from rabbit oviduct epithelial cells was constructed, and screened with a polyclonal antibody against DPF-1 (64 kDa). 4 immunopositive plaques (DPF-1.1, DPF-1.2, DPF-1.3 and DPF-1.4) were purified. The polyclonal antibodies were epitope-selected respectively against the fused proteins produced by these positive recombinant plaques. Identification of recombinant clones by epitope selection revealed that the epitope-selected antibodies from DPF-1.1, DPF-1.2 and DPF-1.3 could recognise not only DPF-1, but 44 kDa protein also (Fig. 2). By using EcoRI-Not1 digestion method, the insert cDNA fragment size of these three recombinants was revealed to be 0.8 kb, 1.2 kb and 1.2 kb respectively (Fig. 3). These cDNA fragments were then isolated and subcloned into pBluescriptKS, and recombinant plasmids (pDPF-1.1, pDPF-1.2 and pDPF-1.3) were constructed (Fig. 4). Dot blot hybridization with a 32p-labeled 1.2 Kb-insert of cDNA from pDPF-1.3 indicated that these recombinant plasmids could cross-hybridized (Fig. 5), further indicating that they all possessed a common nucleic acid sequence. Dot and Northern blotting analysis of total RNA prepared from eight different tissues (skeleton muscle, heart, kidney, oviduct, liver, spleen, lung and small intestine) showed that the gene encoding DPF-1 was expressed specifically in the oviduct tissue (Fig. 6, Fig. 7).

Hydrogen bonding effects on amine rotation rates in crystalline amino acids

Rates of rotation for amines in a variety of crystalline environments are reported, and the trends are explained in terms of the strengths of local hydrogen bonding interactions. Proton spin-lattice relaxation times (T1) and deuterium broad-line NMR spectra have been measured for D-, DL- and L- aspartic acid, two polymorphs of glycine, alanine, and leucine in the temperature range from -40 to 110 degrees C. The energy barriers for amine rotation are 27 +/- 2 kJ mol-1 for D- or L-aspartic acid and 22 +/- 2 kJ mol-1 for DL-aspartic acid; these energies are slightly lower than the previously reported value for the L from based on direct proton T1 measurements at 60 MHz. The values for the alpha and gamma forms of glycine were 24 +/- 2 and 30 +/- 2 kJ mol-1 respectively, that for L-alanine was 40 +/- 2 and that for L-leucine was 49 +/- 3 kJ mol-1. These are all in rough agreement with previously reported values (although the differences for the polymorphs of glycine and for L- vs. DL-aspartic acid were not reported). Crystal structures of these amino acids indicate differences in hydrogen bonding environments around the R-NH3+ groups that are probably responsible for the different activation barriers. A molecular mechanics calculation of the rotation energy barriers for L- and DL-aspartic acid based on the crystal structures gave satisfactory agreement with experimental results if a uniform (and arbitrarily chosen) dielectric constant of 2.5 was assumed. Differences between L- and DL-aspartic acids and between two polymorphs of glycine were well represented qualitatively. Including additional neighboring molecules not involved in the hydrogen bonding or including periodic boundary conditions to describe the crystal packing did not significantly affect these results. If vacuum dielectric constants are used, the barriers are uniformly overestimated, and if the experimental macroscopic dielectric constant values are used, the barriers are generally underestimated. Dielectric constants differ substantially from one amino acid to another and significantly affect the estimated barriers; in fact, the bulk dielectric constants appear to be the major difference between the highest and the lowest values. The difficulty of accurately including dielectric relaxation into molecular mechanics calculations resulted in the disagreement between experimental measurements and theoretical calculations.

Anti-lipid peroxidation of gomisin J on liver mitochondria and cultured myocardial cells

AIM

To study the influences of gomisin J on lipid peroxidation and calcium paradox.

METHODS

Using two in vitro models of rat liver mitochondria membrane lipid peroxidation (LPO) and cultured myocardial cells.

RESULTS

Gomisin J inhibited Fe2+/ascorbic acid and ADP/NADPH-induced LPO with IC50 (95% confidence limits) 5.5 (4.5-6.7) and 4.7 (2.8-7.8) mumol.L-1, respectively, when cultured myocardial cells preincubated with Ca(2+)-free medium for 2 min were incubated with normal medium containing Ca2+, a marked increase of malondialdehyde (MDA) formation occurred and gomisin J 10 mumol.L-1 protected myocardial cells through decreasing MDA formation.

CONCLUSION

Gomisin J inhibits LPO in rat liver mitochondria and protects cultured myocardial cells from being injured by calcium paradox.

In vivo nuclear transport kinetics in Saccharomyces cerevisiae: a role for heat shock protein 70 during targeting and translocation

The transport of proteins into the nucleus is a receptor-mediated process that is likely to involve between 50-100 gene products, including many that comprise the nuclear pore complex. We have developed an assay in Saccharomyces cerevisiae for the nuclear transport of green fluorescent protein fused to the SV-40 large T antigen nuclear localization signal (NLS-GFP). This assay allows the measurement of relative NLS-GFP nuclear import rates in wild-type and mutant cells under various physiological conditions. Probably the best understood component of the nuclear transport apparatus is Srp1p, the NLS receptor, which binds NLS-cargo in the cytoplasm and accompanies it into the nucleus. When compared to SRP1+ cells, NLS-GFP import rates in temperature-sensitive srp1-31 cells were slower and showed a lower temperature optimum. The in vivo transport defect of the srp1-31 cells was correlated with the purified protein's thermal sensitivity, as assayed by in vitro NLS peptide binding. We show that the kinetics of NLS-directed nuclear transport in wild-type cells is stimulated by the elevated expression of SSA1, which encodes a cytoplasmic heat shock protein 70 (Hsp70). Elevated Hsp70 levels are sufficient to suppress the NLS-GFP import defects in srp1-31 and nup82-3 cells. NUP82 encodes a protein that functions within the nuclear pore complex subsequent to docking. These results provide genetic evidence that Hsp70 acts during both targeting and translocation phases of nuclear transport, possibly as a molecular chaperone to promote the formation and stability of the Srp1p-NLS-cargo complex.

Influence of tooth surface conditions on enamel fluoride uptake after topical application of TiF4 in vitro

Three groups of extracted human teeth were sectioned longitudinally into experimental and control halves. The enamel surfaces of the three groups of teeth were pretreated with 37% H3PO4 for 1 min, 0.5 M NaClO3 for 2 h, or water rinsing for 10 min. The experimental halves of the three groups received an application of 1% TiF4 for 1 min and were washed with deionized water. The tooth specimens were then immersed in synthetic saliva for 24 h at 37 degrees C before sampling for measurement of fluoride uptake. An acid etching technique was used to determine the uptake of fluoride by measuring both fluoride and calcium concentrations in the solution collected from each etched sample. A significantly higher uptake of fluoride was found in teeth rinsed in water and etched with 37% H3PO4 than in teeth pretreated in 0.5 M NaClO3. It seems that the organic components in enamel play an important role in the fluoride uptake after the topical application of TiF4.

In vitro selection and molecular characterization of human immunodeficiency virus type 1 with reduced sensitivity to 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA)

9-[2-(Phosphonomethoxy)ethyl]adenine (PMEA) is an acyclic nucleotide with potent in vitro activity against human immunodeficiency virus type 1 (HIV-1). The present study was undertaken to determine whether HIV-1 resistance to PMEA could be generated by in vitro selection and if so, to determine which mutations in reverse transcriptase (RT) were responsible. HIV-1LAI was serially passaged for 10 months in the presence of increasing concentrations of PMEA up to a maximum of 40 microM. After 40 passages, the 50% inhibitory concentration (IC50) of PMEA had increased almost 7-fold from 4.45 to 30.5 microM. Some cross-resistance to 2',3'-dideoxycytidine (ddC, zalcitabine), 2',3-dideoxyinosine (ddI, didanosine), and 3'-thiacytidine (3TC, lamivudine) was also observed, but no cross-reactive resistance to 3'-azido-3'-thymidine (AZT, zidovudine). Sequencing of the RT encoding region of each of eight pol clones from resistant isolates revealed a Lys-65-->Arg (K65R) substitution. HIV with the K65R mutation inserted by site-directed mutagenesis also had decreased sensitivity to PMEA in H9 cells and a similar cross-resistance profile. Thus, HIV can develop decreased sensitivity to PMEA after long-term in vitro exposure and this change is associated with a K65R substitution. Additional studies will be needed to determine whether a similar mutation in HIV RT develops in patients receiving PMEA or its orally bioavailable prodrug adefovir dipivoxil (bis-POM PMEA).

Construction and expression of single-chain Fv antibody against human bladder carcinoma

We designed two sets of oligonucleotide primers to amplify the immunoglobulin heavy- and light-chain variable-region genes from genomic DNA by polymerase chain reaction (PCR). The genomic DNA was extracted from hybridoma BDI-1 cells, which secreted a monoclonal antibody (mAb) against human bladder carcinoma. The primers contained special restriction sites that allowed the variable-region genes to be easily cloned for sequencing and expression. The recombinants were sequenced by Sanger's method. It was proved that the full lengths of the VH and VK genes were 366 and 324 bp, respectively. Compared with other published sequences, the VH gene was a member of mouse heavy-chain VH subgroup II and originated from the rearrangement of VH, Dsp2.2 and JH4. The VK gene was VK subgroup IV and from VK and JK4. The VH and VK genes was inserted expression vector pWAI80. By inducement, the ScFv antibodies were expressed and secreted from Escherichia coli. Binding activities against the bladder carcinoma cells were detected. We suggest that ScFv antibody recognized the antigen specifically.

The K65R mutation confers increased DNA polymerase processivity to HIV-1 reverse transcriptase

The K65R mutation in HIV-1 reverse transcriptase (RT) is associated with viral cross-resistance to 2',3'-dideoxyinosine, 2',3'-dideoxycytidine, and 2',3'-dideoxy-3'-thiacytidine. We have found that in vitro DNA synthesis by K65R RT is significantly more processive than that of wild type (wt) RT. Depending on the template/primer (T/P) used, the total incorporation of nucleotides under single processive cycle conditions was 20-50% higher with K65R RT than with wt RT. With heteropolymeric T/P, the total incorporation of dNMP by K65R and wt RT was similar under continuous DNA synthesis reaction conditions. However, under single processive cycle conditions, the rate of full-length polymerization product synthesis by K65R RT was about 2-fold higher than that by wt RT. We also found a decreased rate of T/P dissociation during K65R RT DNA synthesis, which is consistent with the increased processivity of the enzyme. We postulate that the increased processivity of the K65R RT may be a compensatory response to the decreased affinity of this mutant for certain dNTP substrates, allowing normal viral replication kinetics.

Endogenous reverse transcription assays reveal high-level resistance to the triphosphate of (-)2'-dideoxy-3'-thiacytidine by mutated M184V human immunodeficiency virus type 1

Kinetic analysis showed that the Ki values and the Ki/Km ratios for mutated, recombinant M184V human immunodeficiency virus type 1 reverse transcriptase (RT) for (-)2'-dideoxy-3'-thiacytidine triphosphate (3TCTP) were 35-fold higher than the equivalent values for wild-type RT but only about twice as high as the equivalent values for each of the triphosphates of ddC (ddCTP) and ddA (ddATP). Fully endogenous RT assays showed that viruses containing the M184V substitution were highly resistant to 3TCTP, with an increase in the 50% inhibitory concentration of 250-fold in comparison with wild-type recombinant virus.

Studies of neutralizing monoclonal antibody to human immunodeficiency virus type 1 reverse transcriptase: antagonistic and synergistic effects in reactions performed in the presence of nucleoside and nonnucleoside inhibitors, respectively

We have assessed interactions between the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) and a neutralizing monoclonal antibody (1E8) that hinders binding of deoxynucleoside triphosphate (dNTP) substrates. Steady-state reactions with homopolymeric template-primers revealed that 1E8 antagonized inhibition of RT activity mediated by 3'-azido-3'-deoxythymidine triphosphate and 2',3'-dideoxycytidine triphosphate. However, an additive or synergistic inhibition of RT polymerase activity was noted when 1E8 and the nonnucleoside RT inhibitors nevirapine and delavirdine were studied. Chain elongation and dNTP incorporation studies using an HIV-1 genome-derived heteropolymeric template and either oligodeoxynucleotide or tRNA3(Lys) as the primer yielded results consistent with the above observations. 1E8 also increased pausing at certain sites during synthesis of negative-strand, strong-stop DNA, whether or not ddNTP and nonnucleoside RT inhibitors were present.

Resistance to (-)-2',3'-dideoxy-3'-thiacytidine (3TC) in HIV-1 isolated from paediatric patients

We conducted detailed virological evaluations of 16 HIV-1-infected paediatric patients treated with 3TC (lamivudine) monotherapy. High-level phenotypic resistance against this compound (up to 2,500-fold) was seen in virtually all cases, usually within 8-12 weeks of initiation of therapy. This was concomitant with the appearance of the M184V mutation in viral reverse transcriptase, previously shown to be responsiblefor such resistance. Viral burden fell in virtually all cases after commencement of therapy, and remained below baseline in each instance studied, despite a rebound effect and the appearance of drug resistance. Viral isolates from some patients underwent a switch from a non-syncytium-inducing (NSI) to a syncytium-inducing (SI) phenotype during the course of the study, although no relationship was apparent between dose of drug employed, time to development of drug resistance or time of appearance of SI phenotype.

Enhanced fidelity of 3TC-selected mutant HIV-1 reverse transcriptase

Monotherapy with (-)2',3'-dideoxy-3'-thiacytidine (3TC) leads to the appearance of a drug-resistant variant of human immunodeficiency virus-type 1 (HIV-1) with the methionine-184 --> valine (M184V) substitution in the reverse transcriptase (RT). Despite resulting drug resistance, treatment for more than 48 weeks is associated with a lower plasma viral burden than that at baseline. Studies to investigate this apparent contradiction revealed the following. (i) Titers of HIV-neutralizing antibodies remained stable in 3TC-treated individuals in contrast to rapid declines in those treated with azidothymidine (AZT). (ii) Unlike wild-type HIV, growth of M184V HIV in cell culture in the presence of d4T, AZT, Nevirapine, Delavirdine, or Saquinavir did not select for variants displaying drug resistance. (iii) There was an increase in fidelity of nucleotide insertion by the M184V mutant compared with wild-type enzyme.

[A study of intraarticular irrigation-injection therapy of temporomandibular joint and its mechanism]

According to the research that there were some immune and inflammatory substances in the synovial fluid of temporomandibular joint disturbance syndrome (TMJDS), we improved the traditional intraarticular injection and developed an intraarticular irrigation-injection therapy to treat 43 cases of TMJDS and got a good result. The controls include two groups, the simple rinsing and the traditional injection. Statistical analysis showed a highly significant difference in the effects between test and control groups. In order to study the mechanism of the therapy, the tumor necrosis factor (TNF) in synovial fluid of 8 cases were assessed. It was found that the concentration of TNF was reduced markedly after treatment. We think that the new therapy is effectable for TMJDS and could be used widely.

[A primary study on treatment of intracranial hematomas with specially designed needle puncture]

We treat hematomas by special designed needles and other techniques for breaking and liquefying hematoma. This method is easy to learn and needn't operation room, even can be done at the patient's bedside. Its merits the included point wound without craniotomy, low medical cost and satisfactory result. We treat 112 patients with hypertensive intracranial hematomas, 25 patients with acute epidural hamatoma and 17 patients with hematoma due to other causes. In the total of 154 patients, 20 had brain herniations and 104 coma. The mortality was very low (8.44%). 94 patients (91.34%) woke up in 1 to 2 weeks.

Single-step purification of recombinant wild-type and mutant HIV-1 reverse transcriptase

We have devised a single-step method that enables purification of HIV-1 recombinant reverse transcriptase directly from bacterial lysates in less than 2 h. Clarified lysates are applied to commercial Q- and S-matrix cartridge columns connected in series. The columns are washed with low-salt buffer to remove unbound protein, then the Q column is removed and reverse transcriptase is eluted from the S column using a salt gradient. The purification has been carried out with both medium-pressure and high-pressure chromatographic systems. Purifications are carried out at room temperature near neutral pH, providing enzyme with high DNA polymerase specific activity. A crucial aspect of the procedure is the use of Tris buffer, a buffer that is normally incompatible in cation-exchange methods. The method is applicable for the purification of the p51/p66 heterodimer and the p5l and p66 homodimer forms of reverse transcriptase. We have used this method to purify wild-type reverse transcriptase and several recombinant proteins containing mutations correlated with dideoxynucleoside drug resistance.

Effects of 3'-deoxynucleoside 5'-triphosphate concentrations on chain termination by nucleoside analogs during human immunodeficiency virus type 1 reverse transcription of minus-strand strong-stop DNA

We have compared the effects of nucleoside analogs in quiescent and phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) exposed to human immunodeficiency virus type 1 (HIV-1) with those of their triphosphorylated derivatives in cell-free HIV-1 reverse transcription assays. We observed a substantial decrease in synthesis of early minus-strand proviral DNA products in HIV-1-infected, quiescent PBMC exposed to each of 3'-azido-3'-deoxythymidine (AZT), 2',3'-dideoxyinosine (ddI), and 2',3'-dideoxy-3'-thiacytidine (3TC), in comparison with nontreated, infected controls. In contrast, no such diminution was observed when PHA-stimulated, HIV-1-infected PBMC were treated with the same drugs. This result was attributed to previously reported findings that PHA-stimulated PBMC possessed larger deoxynucleoside triphosphate (dNTP) pools than quiescent cells did. To further investigate this subject, a cell-free HIV-1 reverse transcription reaction involving HIV-1 RNA genomic template, recombinant purified HIV-1 reverse transcriptase, all four dNTPs and either tRNA3Lys or a deoxyoligonucleotide as primer was used to monitor chain termi-nation mediated by 2',3'-dideoxynucleoside triphosphates (ddNTPs) during synthesis of minus-strand strong-stop DNA. Augmented chain termination was observed with decreasing concentrations of both ddNTP and dNTP when the ratio of dNTP to ddNTP was fixed. We also found that both the number and strength of reverse transcription pause sites were increased at low concentrations of dNTPs and when a deoxyoligonucleotide primer was used in place of the cognate primer, tRNA3Lys. Preferential incorporation of ddATP was observed dur-ing reverse transcription opposite a distinct pause site in a short synthetic RNA template. These results con-firm the notion that the antiviral activities of ddNTP are dependent on both cellular dNTP pools and the state of cellular activation. Pausing of HIV-1 reverse transcriptase during reverse transcription, altered by dNTP concentrations, may be a mechanism that controls the position and extent of incorporation of nucleoside analogs.

Squamotacin: an annonaceous acetogenin with cytotoxic selectivity for the human prostate tumor cell line (PC-3)

The bark extracts of Annona squamosa yielded a new bioactive acetogenin, squamotacin (1), and the known compound, molvizarin (2), which is new to this species. Compound 1 is identical to the potent acetogenin, bullatacin (3), except that the adjacent bistetrahydrofuran (THF) rings and their flanking hydroxyls are shifted two carbons toward the gamma-lactone ring. Compound 1 showed cytotoxic selectively for the human prostate tumor cell line (PC-3), with a potency of over 100 million times that of Adriamycin.

[Amplification, cloning and sequence analysis of the variable region genes of monoclonal antibody against human bladder carcinoma]

We have designed two sets of oligonucleotide primers to amplify the immunoglobulin heavy- and light-chain variable region genes from genomic DNA by the polymerase chain reaction, PCR. The genomic DNA was extracted from hybridoma BDI-1 cell, which secrets a monoclonal antibody against human bladder carcinoma. The primers contain special restriction sites that allow the variable region genes to be easy to cloning for sequencing and expression. The PCR products were ligated to plasmid PUC19. The recombinants were sequenced with Sanger's method. It was proved that a full-length VH and V kappa genes was 366 and 324 base pairs respectively. Comparaing with other published sequences, the VH gene was a member of mouse heavy-chain VH subgroup II and originated from rearrangement of VH, Dsp2.2 and JH4; the V kappa gene was V kappa subgroup IV and from V kappa and J kappa 4. It was suggested that obtained VH and V kappa genes were potentially functional genes of the monoclonal antibody against human bladder carcinoma.

Effects of non-nucleoside inhibitors of human immunodeficiency virus type 1 in cell-free recombinant reverse transcriptase assays

We have employed a cell-free human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) assay to study the effects of non-nucleoside inhibitors of RT (NNRTI) by directly monitoring specific HIV DNA products using a HIV-1 genome-derived template and an oligodeoxynucleotide primer. As previously shown by ourselves and others, nucleoside analog triphosphates, e.g. 3'-azido-3'-deoxythymidine triphosphate and 2',3'-dideoxyadenosine triphosphate, could directly inhibit HIV RT RNA-dependent DNA polymerase activity by causing chain termination, as visualized in a RT reaction that yields specific DNA products. In contrast, each of two NNRTIs, nevirapine and delavirdine, directly inhibited RT activity without causing chain termination effects. We also analyzed interactions between nucleoside analogs and NNRTIs or among NNRTIs by chain elongation/dNTP incorporation and/or steady-state kinetic assays. Combinations of nevirapine with the triphosphates of either the (-)-strand of 2',3'-dideoxy-3'-thiacytidine or 2',3'-dideoxyadenosine yielded additive/synergistic effects on RT activity. However, only an additive effect was observed when combinations of nevirapine and 3'-azido-3'-deoxythymidine triphosphate were employed. Combinations of nevirapine and delavirdine had an antagonistic effect on the inhibition of HIV-1 RT activity.

Effect of human papillomavirus type 16 oncogenes on MAP kinase activity

The mitogen-activated protein (MAP) kinase signal transduction pathway is an intracellular signaling cascade which mediates cellular responses to growth and differentiation factors. The MAP kinase pathway can be activated by a wide range of stimuli dependent on the cell types, and this is normally a transient response. Oncogenes such as ras, src, raf, and mos have been proposed to transform cells in part by prolonging the activated stage of components within this signaling pathway. The human papillomavirus (HPV) oncogenes E6 and E7 play an essential role in the in vitro transformation of primary human keratinocytes and rodent cells. The HPV type 16 E5 gene has also been shown to have weak transforming activity and may enhance the epidermal growth factor (EGF)-mediated signal transduction to the nucleus. In the present study, we have investigated the effects of the oncogenic HPV type 16 E5, E6, and E7 genes on the induction of the MAP kinase signaling pathway. The E5 gene induced an increase in the MAP kinase activity both in the absence and in the presence of EGF. In comparison, the E6 and E7 oncoproteins do not alter the MAP kinase activity or prolong the MAP kinase activity induced with EGF. These findings suggest that E5 may function, at least in part, to enhance the cell response through the MAP kinase pathway. However, the transforming activity of E6 and E7 is not associated with alterations in the MAP kinase pathway. These findings are consistent with E5 enhancing the response to growth factor stimulation.

Inhibition of human immunodeficiency virus type 1 multiplication by transforming growth factor beta 1 and AZT in HIV-1-infected myeloid cells

Myeloid cells are important reservoirs of HIV-1 infection. In response to pathogenic agents, macrophages secrete inflammatory cytokines that can modulate viral replication and contribute to AIDS pathogenesis. Because HIV replication is dependent on cellular activation, immunosuppressive cytokines that deactivate macrophages and T cells may be important modulators of an antiviral effect. We tested the anti-HIV potential of the immunosuppressive cytokine-transforming growth factor beta (TGF-beta 1) alone and in combination with AZT in a new monomyeloblastic model of HIV-1 infection. The PLB-985 cell model was infected with HIV IIIB strain, and the course of HIV-1 infection and replication was monitored by reverse transcriptase assay, p24 immunofluorescence, and northern blot analysis of HIV-1-specific mRNA. TGF-beta 1 as a single agent had no effect on the multiplication of HIV-IIIB in de novo-infected PLB 985 monomyeloblastic cells. However, cotreatment with TGF-beta 1 and AZT synergistically slowed virus multiplication within the first week following infection, as determined by reverse transcriptase measurement, p24 antigen detection, and northern blot analysis of viral RNA. The synergistic actions of TGF-beta 1 and AZT were also observed in PLB 985 cells infected with an AZT-resistant strain of HIV-1 (HIV 1393). Synergism between nucleoside analogs and cytokines may be an important therapeutic approach to HIV-1 infection. Elucidation of the role of cytokines in controlling the degree of HIV multiplication may have an impact on both clinical treatments and understanding the progression to AIDS.

Possible involvement of cell fusion and viral recombination in generation of human immunodeficiency virus variants that display dual resistance to AZT and 3TC

We have attempted to relate genetic recombination involving human immunodeficiency virus type 1 (HIV-1) to multiple drug resistance by using PEG to fuse subclones of U937 cells that carried HIV-1 recombinants resistant to either 3' -azido-3'-deoxythymidine (AZT) or the (--) enantiomer of 2',3'-dideoxy-3'-thiacytidine (3TC). The parental viruses employed contained well-defined mutations in the pol gene. Fused cells were co-cultured with the MT4 lymphocyte cell line for virus amplification to yield progeny that, in some cases, possessed different patterns of drug resistance from parental viruses. Mutational analyses were performed by PCR to substantiate these observations, which were also confirmed by direct sequencing of single strands of DNA segments, obtained from plaque-purified viruses. These studies indicate that viral recombination had occurred, and establish a theoretical basis on which to conclude that the acquisition of multiple drug resistance on the part of HIV-1 may be related to its ability to promote cell fusion.

K65R mutation of human immunodeficiency virus type 1 reverse transcriptase encodes cross-resistance to 9-(2-phosphonylmethoxyethyl)adenine

Cloned variants of human immunodeficiency virus type 1 that contain the K65R mutation in reverse transcriptase have previously been shown to display approximately 10- to 30-fold resistance against 2',3'-dideoxycytidine, 2',3'-dideoxyinosine, and 2',3'-dideoxy-3'-thiacytidine. On the basis of tissue culture studies with both primary T cells and established cell lines, we now report that the K65R mutation confers approximately 12- to 15-fold resistance to 9-(2-phosphonylmethoxyethyl)adenine (PMEA). Likewise, a chain termination system revealed that mutated recombinant K65R reverse transcriptase displays resistance to PMEA diphosphate, the active metabolite of PMEA, in cell-free enzyme assays. Parallel studies have shown that the M184V mutation in reverse transcriptase, associated with high-level resistance against the (-) enantiomer of 2',3'-dideoxy-3'-thiacytidine, does not confer resistance to PMEA in tissue culture. Viruses and enzymes that included both the K65R and M184V mutations were resistant to PMEA and PMEa diphosphate, respectively, but only to the extent conferred by the K65R mutation alone.

The effect of levonorgestrel-releasing intrauterine device (20 micrograms/day) (LNG-IUD-20) on the morphological structure of human endometrium: a study of the endometrial factor VIII activity in the women before and after insertion of LNG-IUD-20 by the digital image analysis

The specimens of endometria were obtained from 18 women using an intrauterine device releasing levonorgestrel at 20 micrograms/day (LNG-IUD-20). An immunoperoxidase reaction, PAP method, with the antiserum of Factor VIII as the primary antibody, was carried out in the endometrial biopsies to detect the Factor VIII activity in the endometrial endothelium before and after insertion of LNG-IUD-20. The immunoperoxidase activity was quantitatively assessed by a computer digital image analyser. The results revealed that there were a lower Factor VIII activity in the endometrial endothelial cells after insertion of LNG-IUD-20 (p < 0.001) when compared with the control. From the results of the present study, it is suggested that the synthesis and release of endometrial endothelial Factor VIII might be inhibited by the insertion of LNG-IUD20.

A morphometric study on the endometrial activity of women before and after one year with LNG-IUD in situ

The endometrium was studied by morphometry in 34 healthy women before and after one year's use of an IUD releasing levonorgestrel at a rate 20 micrograms/24 hr (LNG-IUD-20). The effect was compared with that of an IUD releasing 2 micrograms levonorgestrel/24 hr (LNG-IUD-2). The appearance of suppressed endometrial proliferative activity and increased inflammatory reaction was similar in the two experimental groups, suggesting that the morphological alterations were independent of the LNG dosage. The result of this study, combined with clinical data, suggests that LNG-IUD-20 could replace LNG-IUD-2 without any additional side effects. The efficacy of LNG-IUD-20 is also likely to last for a longer period than the LNG-IUD-2.

Envelope V3 region sequences of Cuban HIV-1 isolates

The origin of HIV-1 species, responsible for the AIDS epidemic in Cuba, is a subject that has been intensely debated. This study represents an initial attempt to shed light on this issue, through sequence analysis of the V3 regions of viruses isolated from 15 Cuban subjects. We now report that these viruses fall within three distinct, well-recognized groupings. These findings suggest that viruses of different sources are responsible for the HIV/AIDS epidemic in Cuba.

Structural and ultrastructural studies of the synovial membrane in temporomandibular joint disturbance syndrome

To gain further knowledge on temporomandibular joint disturbance syndrome (TMJDS), the synovial membranes of 7 patients and 3 cadavers were examined with light microscope and transmission electron microscope. The results showed that the synoviocytes degenerated or disappeared in TMJDS. The cytoplasm contained numerous fibrils, while the organelles diminished in number. The surface of the synovial membrane was covered with a fibrinoid material. The surface of the synovial membrane was covered with a fibrinoid material. The authors consider that these pathological changes reduce or eliminate the normal functions of the synovial membrane, which may lead to damage to the articular cartilage. The articular adhesion found sometimes in TMJDS may be related to the changes in the synovial membrane.

A gratuitous inducer of cat-86, amicetin, inhibits bacterial peptidyl transferase

Expression of the chloramphenicol resistance gene cat-86 is regulated by translation attenuation. Among the three ribosomally targeted antibiotics that can induce the gene, only amicetin has an unknown mode of action. Here we demonstrate that the nucleoside antibiotic amicetin is an inhibitor of bacterial peptidyl transferase. Thus, the three inducers of cat-86, chloramphenicol, erythromycin, and amicetin, interact with the peptidyl transferase region of bacterial ribosomes.

Development of HIV-1 resistance to (-)2'-deoxy-3'-thiacytidine in patients with AIDS or advanced AIDS-related complex

OBJECTIVE

To determine the rate of development of in vitro HIV resistance to (-)2'-deoxy-3'-thiacytidine (3TC) and relate the effect of dose to emergence of resistance.

METHODS

HIV-infected men and non-pregnant women, aged > or = 18 years, with a CD4 count < or = 300 x 10(6)/l cells were followed in a Phase I/II study, in which they were evaluated for tolerance to 3TC and effect of this agent with regard to viral susceptibility. Peripheral blood and plasma samples were collected at regular intervals for analysis. HIV was isolated using umbilical cord blood mononuclear cells as targets. These cells were also used in determinations of median inhibitory drug concentration. Specific amplification of the 184 mutation site, associated with HIV resistance to 3TC, was performed by polymerase chain reaction, using specific primer pairs, on DNA harvested from infected peripheral blood mononuclear cells (PBMC) of donors or, alternatively, on DNA that had been reverse transcribed from plasma-associated HIV RNA.

RESULTS

Phenotypic resistance was detected in approximately one-third of individuals studied, who were followed between 8 and 56 weeks. Development of 3TC resistance occurred independently of dose, although time of first appearance of resistant HIV-1 variants appeared reduced at high 3TC doses. Amino-acid changes at codon 184 in HIV-1 reverse transcriptase were associated with, and preceded, the development of phenotypic 3TC resistance. Most commonly, a Met to Ile substitution appeared transiently before being superceded by a Val substitution at codon 184.

CONCLUSIONS

In vitro resistance to 3TC developed in a high proportion of subjects who received prolonged monotherapy with this drug. The development of resistance to 3TC was associated with appearance of mutated viral forms and the disappearance of wild-type virus, with regard to codon 184, in both patient plasma and PBMC.

Mutated K65R recombinant reverse transcriptase of human immunodeficiency virus type 1 shows diminished chain termination in the presence of 2',3'-dideoxycytidine 5'-triphosphate and other drugs

A lysine-to-arginine substitution at amino acid 65 (K65R) in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is associated with resistance to 2',3'-dideoxycytidine (ddC), 2',3'-dideoxyinosine (ddI), and the (-) enantiomer of 2',3'-dideoxy-3'-thiacytidine (3TC). To further characterize the molecular basis of such resistance, we expressed the pp6/p51 heterodimer of wild-type RT, K65R mutated RT, and a doubly mutated (K65R/M184V) RT in Escherichia coli and assessed the characteristics of nucleotide incorporation and chain termination in cell-free reverse transcription reactions in the presence and absence of various nucleoside triphosphate analogs. These reactions employed a HIV RNA template (HIV-PBS) that contained the primer binding sequence (PBS) and the U5 and R regions of HIV-1 genomic RNA and an oligodeoxynucleotide (dPR) complementary to the HIV-1 PBS as primer. The K65R and K65R/M184V RTs showed significantly decreased chain-termination effects during polymerization with the 5'-triphosphates of ddC, 3TC, 2',3'-dideoxyadenosine, and AZT (3'-azido-3'-deoxythymidine) in comparison with wild-type RT. Detailed analysis with ddCTP and wild-type RT revealed that chain termination occurred at all guanines in the RNA template. However, the frequency of dideoxynucleoside triphosphate (ddNTP)-induced chain termination was decreased at certain guanines but not others in reactions catalyzed by K65R RT. Both the K65R mutant RT and wild-type RT had similar processive activity. These results indicate that decreased chain termination of K65R RT in the presence of ddNTPs is consistent with data obtained in viral replication assays.

[The effect of estrogen and its receptor antagonist on the growth of human gastric cancer cell line in vitro]

In this study, the effect was studied of estradiol (E2) and tamoxifen on the growth of a human gastric adenocarcinoma SGC-7901 cell line in vitro. Estrogen receptor as revealed by immunohistochemical staining was positive when added at various concentrations. E2 could significantly stimulate cell growth. The effect was most marked at concentration of 0.1 mumol/L. The cell doubling time was reduced, the plating efficiency was increased and c-myc oncogene expression was enhanced. Flow cytometric analysis indicated that cell] proliferation index was greater in the E2-treated than in the control. All these effects caused by E2 could be partially inhibited by the estrogen receptor inhibitor tamoxifen.

Social aspects of malaria in Heping, Hainan

This paper presents findings from a study conducted in Heping Town, Qiongzhong County, Hainan Province, China. The study, conducted in 1992, used qualitative as well as quantitative methods to gather social, cultural and behavioural data associated with the acquisition, transmission and prevention of malaria, and the diagnosis and treatment of disease. These methods included focus groups, key informant and other in-depth interviews, and observations, a household survey and tests of school children of knowledge of malaria. The study is among the first to our knowledge that has utilized this broad mix of methods for tropical disease research in China.

[Molecular basis and clinical significance of HIV-1 resistance to nucleoside compounds]

The prolonged use of anti-viral nucleosides (ZDV, ddI, ddC) in HIV-infected patients has given rise to the isolation of viral variants that display resistance against these compounds. Tissue culture selection experiments, involving increasing concentrations of anti-viral compounds, have likewise been shown to select for drug-resistant strains of HIV. Cloning, sequencing and site-directed mutagenesis have shown that a series of point mutations in the viral reverse transcriptase (RT) are responsible for this phenomenon. A different series of mutations in RT are responsible for resistance against non-nucleoside inhibitors of this enzyme. These mutations are due to the error-prone nature of RT during viral replication. Mutated forms of recombinant RT, that derive from drug-resistant viruses, have reduced affinity for relevant triphosphorylated nucleosides.