[Construction and analysis of soybean genetic map]

Molecular linkage maps provide a powerful tool for the analysis of plant genome structure and function including the detection of quantitative trait loci (QTL). The molecular linkage map of soybean was constructed using an 88-individual RIL population derived from a cross between cultivated Changnong 4 and semi-wild Xinmin 6. The map contains 22 linkage groups and 240 markers, including 100 RFLP, 33 SSR, 62 RAPD, 42 AFLP, 1 SCAR and 2 morphological markers. It covers approximately 3,713.5 cM of soybean genome. Analysis of 72 RFLP markers showed that 16 of them revealed two or more independent loci and it suggested that there is an extensive homologous region in soybean genome. This map compared very well with the other published soybean maps.

[Segregation distortion of molecular markers in recombinant inbred populations in soybean (G. max)]

The segregation distortion of 238 molecular markers in a RILs population from cultivated/semi-wild soybean cross was analysed. 29.4% of the loci were found with segregation distortion, and direction of deviation was mainly towards cultivated variety Changnong 4. RAPD markers have a higher distortion rate than other molecular markers.

[Soybean germplasm diversity and genetic variance detected by microsatellite markers]

Microsatellite or Simple Sequence Repeats (SSR) marker is a new type of molecular marker developed recently, which can be used in genotype identification, pedigree analysis, and estimation of genetic distance. Using 5 pairs of SSR primer, 21 polymorphic fragments were obtained in 15 soybean germplasm. The number of alleles at each SSR locus is from 3 to 6, and the range of gene diversity is 0.439-0.668. In addition, analysis of genetic distance was also performed in this study. Pedigree analysis showed that mutation occurred for individuals in the F8 population of RIL after multigeneration meiosis, which was caused because of the changes in the number of repeat unit, to a limited extent.

[Inheritance of resistance to Heterodera glycines race 14 in Huibuzhi black bean]

Heterodera glycines is the most serious disease in the world soybean (Glycine max) production. Huibuzhi black bean from Xing County in Shanxi Province, China is one of the most important resistant resources. Using a set of host differentials for soybean cyst nematode and criterion of race classification as well as method of manual inoculation, race 14 was identified as a prevalent one in the soil population of the Experiment Station, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing. A sensitive variety #7 Jidou as a female donor crossed with Huibuzhi black bean. Their offsprings were investigated for resistance to race 14. Two of F1 seedlings demonstrated their resistant. Two populations in F2 including 116 seedlings and 78 seedlings in each one appeared their own separate ratio that was in common: 43R:21S. A genetic hypothesis was proposed that resistance to SCN race 14 in Huibuzhi black bean was controlled by three gene pairs arose. Gene reciprocity existed among them: one recessive epistasis gene pair and two dominant complementary gene pairs. Random 30 families in F3 including 10-15 tested seedlings in each family were screened for resistance to SCN race 14. The segregate ratio, 19R:38Seg.:7S, among F3 families confirmed that the presented genetic hypothesis was correct.

Protocols for implementing DOE authorized release of radioactive scrap metals

A process to implement the U.S. Department of Energy's (DOE) policy for authorized release of radioactive materials from DOE facilities is provided in the Draft Handbook for Controlling Release for Reuse or Recycle of Property Containing Residual Radioactive Material, published by DOE in 1997 and distributed to DOE field offices for interim use and implementation. The authorized release of such property is intended to permit its beneficial use across the entire DOE complex. A computerized management tool--P2Pro(RSM)--has been developed to aid in carrying out the release process for radioactive metals. It contains protocols for the authorized release process and relevant information to facilitate the evaluation of scrap metals for reuse and recycle. The P2Pro(RSM) protocols provide DOE and its contractors with an effective, user-friendly tool for managing authorized release activities P2Pro(RSM) is designed to be used in the Windows environment. The protocols incorporate a relational database coupled with a graphic-user interface to guide the user through the appropriate steps so authorized release limits can be developed. With the information provided in the database, an as-low-as-reasonably-achievable (ALARA) optimization process can be easily set up and run for up to 10 alternatives for disposition of radioactive scrap metals. The results of the ALARA optimization process can be printed in a series of reports and submitted as part of the application for the authorized release of the radioactive scrap metals.

Female bladder neck changes with position

Location of the bladder neck and its dynamic motion are believed to be influenced by body position. This study was designed to evaluate factors affecting bladder neck mobility in both supine and standing positions. The parameters of 75 GSI patients and 49 controls were compared by Student's t-test. Receiver operating characteristic curves and multiple logistic regression analysis were used to analyze the effects of potential contributing factors on bladder neck mobility. We were unable to find any significant correlation between bladder neck hypermobility and GSI. We also failed to demonstrate that bladder neck hypermobility in the supine or standing position relative to previous believed risk factors, including parity, vaginal delivery, menopause, cystocele, rectocele, uterine prolapse or body mass index. In order to elucidate the pathophysiology of bladder neck mobility clearly, changes in intraabdominal pressure and gravitational direction in different positions should be evaluated carefully and scientifically in further studies.

Assessment of decisions in the treatment of Helicobacter pylori-related duodenal ulcer: a cost-effectiveness study

AIMS

Many treatment trials for Helicobacter pylori have been reported but few have evaluated treatment in terms of both cost and effectiveness. It is important to find a therapy with a high eradication rate and low cost, especially in China. The aim of the study is to assess the efficiency of therapy for duodenal ulcers, including ulcer healing, H. pylori eradication and ulcer recurrence.

METHODS

Ninety-six consecutive patients with duodenal ulcers and H. pylori infection were randomly allocated into two groups: AMT group (amoxycillin + metronidazole + tagamet); OA group (omeprazole + amoxycillin). Side-effects were recorded during the treatment period. Endoscopic examinations were repeated at the 7th or 8th week to assess ulcer healing. Patients were followed up for 6 months and repeat endoscopy was performed. Ulcer healing rate, H. pylori eradication rate and ulcer recurrence rate were compared. All costs were recorded and a cost-effectiveness analysis was conducted.

RESULTS

In the AMT and OA groups, the ulcer healing rate was 83.7 and 93.5%, respectively (P = 0.27). The eradication rate of H. pylori was 65.1 and 69.6%, respectively and was significantly higher in patients with an ulcer diameter < or = 1 cm compared with those with an ulcer diameter > 1 cm, irrespective of treatment group. There was no difference in recurrence rate, duration of pain or the time lost because of the disease. Moderate or severe side-effects were found in 8.9% in AMT group and 6.5% in OA group. The cost of treatment for ulcer healing, H. pylori eradication and reduction in ulcer recurrence were all lower in the AMT group than in the OA group. Sensitivity analysis supported the result that AMT was more cost effective than OA.

CONCLUSIONS

The AMT therapy was more effective and less costly than the OA therapy, especially in patients with H. pylori-related duodenal ulcers < 1 cm diameter.

Magnetic split-flow thin fractionation of magnetically susceptible particles

We recently built a magnetic separation system to extend the applications of split-flow thin (SPLITT) fractionation to magnetically susceptible particles. Here, we characterize the magnetic SPLITT system using magnetically susceptible particles and ion-labeled particles. The flow axis of separation channel was orientated parallel and perpendicular to gravitational forces to exclude and include, respectively, gravitational effects on separation. Both operating modes were used to test the theory experimentally, with emphasis on the parallel mode. The magnetic susceptibilities of carrier and ion-labeled particles were varied, and various ion-labeled and unlabeled particles were studied experimentally, resulting in successful separation of labeled particles, yeasts, and cells from unlabeled ones. The minimal difference in magnetic susceptibility (delta(chi)) required for complete particle separation was about 1.75 x 10(-5) [cgs], corresponding to about 10(9) labeling ions per particle in this study. The throughput was around 7.2 x 10(8) particles/h using the present setup. Magnetic SPLITT fractionation shows good potential for use in obtaining particles magnetic susceptibilities from a simple theoretical treatment.

Differential response to benzo[A]pyrene in human lung adenocarcinoma cell lines: the absence of aryl hydrocarbon receptor activation

Benzo[a]pyrene (B[a]P) has been shown to produce DNA adducts and to initiate pulmonary carcinogenesis in animals. We observed differential susceptibility to B[a]P in two human lung adenocarcinoma cell lines, A427 and CL3. DNA adducts were induced by B[a]P treatment in CL3 cells, however, A427 cells were much less responsive to B[a]P treatment. Cytochrome P450 1A1 (CYP1A1) is involved in bioactivation of B[a]P in nonhepatic tissues. Cotreatment with alpha-naphthoflavone, a CYP1A1 inhibitor, abolished DNA adduct formation by B[a]P in CL3 cells. Nevertheless, CYP1A1 inducer beta-naphthoflavone, enhanced DNA adduct formation by B[a]P in both A427 and CL3 cells. Both enzyme activity and mRNA levels of CYP1A1 were highly induced by 1 or 10 microM B[a]P treatment for 24 hr in CL3 cells but not in A427 cells. Protein levels of AhR and aryl hydrocarbon receptor nuclear translocator (Arnt) were similar in A427 and CL3 cells before B[a]P treatment. However, B[a]P induced a retarded band with the [32P]-dioxin responsive element in CL3 cells, but not in A427 cells. This study demonstrated that variation in AhR-mediated CYP1A1 induction contributes to differential susceptibility to B[a]P-DNA adduct formation in human lung cells. Since AhR and/or Arnt function is impaired in A427 cells, this cell line offers a model for investigating the repression mechanisms of CYP1A1 induction by B[a]P in lung cells.

Non-NMDA receptors mediate both pressor and depressor actions of the cardiovascular-reactive areas in the brainstem of cats

L-glutamate (Glu), an important excitatory transmitter in the central nervous system, is mainly mediated via two kinds of ionotropic Glu receptors: N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA)/kainate (non-NMDA) receptors. Microinjection of Glu (0.1 M, 30 nL) into gigantocellular tegmental field (FTG), dorsomedial medulla (DM) and rostral ventrolateral medulla (RVLM) induced increases of the systemic arterial pressure (SAP) and the sympathetic vertebral nerve activities (VNA), while its microinjection into caudal ventrolateral medulla (CVLM) induced decreases of SAP and VNA. In this study, the 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA antagonist, was used to examine the effects of non-NMDA receptors on Glu-induced cardiovascular responses. Cats were anesthetized intraperitoneally with a mixture of urethane (400 mg/kg) and alpha-chloralose (40 mg/kg) and paralyzed with gallamine triethiodide (4 mg/kg, i.v. per hour). CNQX blocked the Glu-induced pressor responses in FTG, DM and RVLM but potentiated the depressor responses in CVLM. These results suggest that non-NMDA receptors modulate the central pressor and depressor responses in an opposite direction. On the other hand, activation of DM and RVLM neurons by application of AMPA (5 mM, 30 nL) evoked pressor responses. These AMPA-induced responses were significantly blocked by CNQX. Interestingly, CNQX itself induced pressor responses in many stimulated points of the pressor areas (FTG: 6/9; DM: 13/24; RVLM: 6/13), indicating a tonic release of Glu mediating depressor effects. In conclusion, non-NMDA receptors within the pressor (FTG, DM and RVLM) and depressor (CVLM) areas may play different modulatory roles in cardiovascular integration. The depressor mechanism mediated by non-NMDA receptors is tonically activated by the release of endogenous Glu in these pressor and depressor areas.

Self-focusing, channel formation, and high-energy ion generation in interaction of an intense short laser pulse with a He jet

Using interferometry, we investigate the dynamics of interaction of a relativistically intense 4-TW, 400-fs laser pulse with a He gas jet. We observe a stable plasma channel 1 mm long and less than 30 microm in diameter, with a radial gradient of electron density approximately 5 x 10(22) cm(-4) and with an on-axis electron density approximately ten times less than its maximum value of 8 x 10(19) cm(-3). A high radial velocity of the surrounding gas ionization of approximately 3.8 x 10(8) cm/s has been observed after the channel formation, and it is attributed to the fast ions expelled from the laser channel and propagating radially outward. We developed a kinetic model which describes the plasma channel formation and the subsequent ambient gas excitation and ionization. Comparing the model predictions with the interferometric data, we reconstructed the axial profile of laser channel and on-axis laser intensity. The estimated maximum energy of accelerated ions is about 500 keV, and the total energy of the fast ions is 5% of the laser pulse energy.

Diterpenoids from isodon eriocalyx

Three new diterpenoids, eriocalyxins C-E (1-3), were isolated from Isodon eriocalyx. Their structures were elucidated as 6beta-hydroxy-15beta-acetoxy-3alpha,20-epoxy-16beta, 17-epoxy-ent-kaur-1,7-dione (1), 1alpha,7beta-dihydroxy-6beta, 15beta-diacetoxy-7,20-epoxy-ent-kaur-16-ene (2), and 15beta-acetoxy-1,6-dioxo-6,7-seco-ent-kaur-2,16-dien-7,20-olide (3), respectively, by means of spectroscopic methods, including one- and two-dimensional NMR techniques.

The effect of Tai Chi on cardiorespiratory function in patients with coronary artery bypass surgery

PURPOSE

This study prospectively evaluated the training effect of a 1-yr Tai Chi Chuan (TCC) program for low-risk patients with coronary artery bypass surgery (CABS) after a postoperative outpatient (phase II) cardiac rehabilitation program.

METHODS

Twenty patients with mean age of 56.5+/-7.4 yr completed this study. The TCC group included nine men who practiced classical Yang TCC with an exercise intensity of 48-57% heart rate range (HRR). The control group included 11 men whom were recommended to do a home-based self-adjusted exercise program with similar intensity of phase II cardiac rehabilitation. Graded exercise tests were performed before and after 1 yr of training for all subjects.

RESULTS

Mean attendance of the TCC group was 3.8+/-1.5 times weekly in contrast to 1.7+/-1.1 times for the control group. During the follow-up examination, the TCC group increased 10.3% in VO2peak (from 26.2+/-4.4 to 28.9+/-5.0 mL x kg(-1) min(-1), P<0.01) and increased 11.9% in peak work rate (from 135+/-26 W to 151+/-28 W, P<0.01). However, the control group showed slight decrease in VO2peak from 26.0+/-3.9 to 25.6+/-4.6 mL x kg(-1) x min(-1) and in peak work rate from 131+/-23 W to 128+/-32 W. At the ventilatory threshold, the TCC group also showed significant increase in VO2 and work rate (P<0.05). The control group did not significantly change in these variables.

CONCLUSIONS

The study demonstrated that a 1-yr TCC program for low-risk patients with CABS could favorably enhance cardiorespiratory function.

Image analysis of p53 and cyclin D1 expression in premalignant lesions of the oral mucosa

OBJECTIVE

The expression of p53 and cyclin D1 proteins was analyzed by image analysis in oral premalignant lesions and normal oral mucosa.

STUDY DESIGN

Punch biopsies from the normal oral mucosa were obtained from 20 normal donors and 41 patients with oral dysplastic leukoplakias. After controlled formaldehyde fixation and paraffin embedding, immunohistochemistry was used to detect cyclin D1 and p53. Image analysis was performed using stain intensity levels established by determining color thresholds (nuclear score) in the basal and parabasal layers.

RESULTS

Analysis of sections showed a similar pattern: only two normal donors had a few intensely positive p53 cells in the basal layer of the floor of the mouth and the tongue epithelia. Similarly, only three donors had intensely positive cyclin D1 cells in the normal epithelia of the same sites. Most cells fell in the range of negative or marginal stain (lower quartiles or terciles of nuclear score). These data on normal mucosa were compared with low grade oral leukoplakias (LGD) with mild to moderate dysplasia and with high grade leukoplakias (HGD) with severe dysplasia. Both markers were differentially expressed in precursor lesions versus normal epithelia. Statistical analysis of our data shows that the intensity of the immunohistochemical stain, as reflected in the nuclear scores of p53, is a reliable parameter that can differentiate between LGD and HGD of the oral mucosa. This was especially true when higher nuclear scores were compared. In contrast, low nuclear scores are more effective in differentiating normal epithelia from dysplastic epithelia. Although cyclin D1 immunohistochemistry does not stain as intensely as p53 stain, similar conclusions can be derived from those data.

CONCLUSION

Image analysis of these two markers proved useful in distinguishing normal oral epithelia from low grade and high grade leukoplakias. With further developments in this field it is hoped that image analysis procedures could be used in different types of studies in which variations of protein expression in tissue sections could have prognostic implications or could be useful to determine subtle effects of curative or preventive treatment.

Substituted 4-hydroxyproline di- and tri-peptides as cytotoxic agents

4-Hydroxyproline di- and tri-peptides and N-cbz-hydroxypropyl- glycinamides were observed to be potent cytotoxic agents against the growth of suspended single cells, L-1210, Tmolt3, and HeLa-S3. The agents were not as potent against the growth of cultured solid tumor cells. Selected derivatives were investigated for their mode of action in Tmolt3 leukemia cells. The compounds selectively inhibited DNA synthesis at 50 and 100 microM. The target site of action of the agents appeared to be the purine de novo pathway with marked inhibition of the activities of the two regulatory enzymes of the pathway, i.e. PRPP amido-transferase and IMP dehydrogenase. d[NTP] pools were reduced by the agents consistent with their overall reduction of DNA synthesis. Other marginally inhibited targets of the agents were r-RNA polymerase and TMP-kinase activities. The DNA molecule itself did not appear to be a target of these agents.

Epithelial sodium channel regulated by aldosterone-induced protein sgk

Sodium homeostasis in terrestrial and freshwater vertebrates is controlled by the corticosteroid hormones, principally aldosterone, which stimulate electrogenic Na+ absorption in tight epithelia. Although aldosterone is known to increase apical membrane Na+ permeability in target cells through changes in gene transcription, the mechanistic basis of this effect remains poorly understood. The predominant early effect of aldosterone is to increase the activity of the epithelial sodium channel (ENaC), although ENaC mRNA and protein levels do not change initially. Rather, the open probability and/or number of channels in the apical membrane are greatly increased by unknown modulators. To identify hormone-stimulated gene products that modulate ENaC activity, a subtracted cDNA library was generated from A6 cells, a stable cell line of renal distal nephron origin, and the effect of candidates on ENaC activity was tested in a coexpression assay. We report here the identification of sgk (serum and glucocorticoid-regulated kinase), a member of the serine-threonine kinase family, as an aldosterone-induced regulator of ENaC activity. sgk mRNA and protein were strongly and rapidly hormone stimulated both in A6 cells and in rat kidney. Furthermore, sgk stimulated ENaC activity approximately 7-fold when they were coexpressed in Xenopus laevis oocytes. These data suggest that sgk plays a central role in aldosterone regulation of Na+ absorption and thus in the control of extracellular fluid volume, blood pressure, and sodium homeostasis.

Cardiorespiratory response of heart transplantation recipients to exercise in the early postoperative period

In this study, we evaluated the cardiorespiratory function of orthotopic heart transplantation (OHT) recipients during exercise. Seventeen male OHT recipients, ranging in age from 22 to 60 years, participated in this study 47 +/- 21 days after surgery. The control group consisted of 17 sedentary healthy men. Breath-by-breath measurement of cardiorespiratory function was obtained during the incremental exercise of leg cycling. At peak exercise, the oxygen (O2) uptake (16.5 +/- 3.3 vs 33.9 +/- 8.2 mL.kg-1.min-1), work rate (82 +/- 19 vs 169 +/- 42 watts), heart rate (HR), O2 pulse, and blood lactate level of the OHT recipients were significantly lower than the respective values of the control group. At the ventilatory threshold, the OHT group also showed a significantly lower O2 uptake (10.7 +/- 1.6 vs 18.3 +/- 5.1 mL.kg-1.min-1), work rate (39 +/- 12 vs 89 +/- 33 watts), HR, O2 pulse, ventilatory equivalent for O2, and ventilatory equivalent for carbon dioxide. The OHT recipients showed a high resting HR (97 +/- 7 beats/min) and a low peak HR (123 +/- 14 beats/min) during exercise, and their HR continued to increase for 1 to 3 minutes after cessation of exercise. Our data revealed a low level of cardiorespiratory endurance in OHT recipients during the early postoperative stage. A multidisciplinary cardiac rehabilitation program should be considered to enhance physical functional capacity and quality of life, and promote return to work.

Reactive oxygen species modulate endothelin-I-induced c-fos gene expression in cardiomyocytes

OBJECTIVES

Recent evidence indicates that reactive oxygen species (ROS) may act as second messengers in receptor-mediated signaling pathways. The possible role of ROS during Et-1 stimulation in cardiomyocytes was therefore investigated.

METHODS

Intracellular ROS levels were measured with fluorescence probe 2',7'-dichlorofluorescin diacetate by confocal microscopy in cultured neonatal rat cardiomyocytes. The ROS-inducible c-fos expression was analyzed by Northern blotting and promoter activity.

RESULTS

Et-1 applied to cardiomyocytes dose-dependently increased intracellular ROS levels. The increase of ROS levels was attenuated by pretreating cardiomyocytes with Et-A receptor antagonist-BQ485, but not with Et-B receptor antagonist. Cardiomyocytes pretreated with catalase or an antioxidant N-acetylcysteine (NAC) reduced Et-1-induced ROS levels. Et-1 or H2O2 treatment of cardiomyocytes rapidly induced the expression of an immediate early gene c-fos. Et-1-treated cardiomyocytes enhanced the c-fos gene expression as revealed by functional analysis using a reporter gene construct containing c-fos promoter region (-2.25 kb) and reporter gene chloramphenicol acetyltransferase. The induction of mRNA levels and the promoter activities of c-fos gene by Et-1 or H2O2 were abolished by pretreating cardiomyocytes with catalase or NAC. Cells transiently transfected with the dominant positive mutant of p21ras (RasL61) led to a significant increase in intracellular ROS. Concomitantly, the mRNA levels and the promoter activities of c-fos were also induced. In contrast, cells transfected with the dominant negative mutant of Ras (RasN17) inhibited Et-1-induced ROS. Consistently, the increase of c-fos mRNA levels and promoter activities by Et-1 were also inhibited.

CONCLUSIONS

These findings clearly indicate that Et-1 treatment to cardiomyocytes can induce ROS via Ras pathway and the increased ROS are involved in the increase of c-fos expression. Our studies thus emphasize the importance of ROS as second messengers in Et-1-induced responses on cardiomyocytes.

Fertilization capability of frozen epididymal sperm for intracytoplasmic sperm injection

Both microsurgical epididymal sperm aspiration (MESA) and intracytoplasmic sperm injection (ICSI) are great advances in assisted reproductive techniques. By using the ICSI technique, frozen sperm from the epididymis can result in successful fertilization. The epididymal sperm retrieved via MESA can be cryopreserved for an in-vitro fertilization (IVF) procedure, thus, making repeat surgical retrieval of sperm unnecessary. We report a retrospective analysis of 24 ICSI cycles in 16 patients with obstructive or nonreconstructable azoospermia. Fresh epididymal sperm was used in 13 ICSI cycles and frozen-thawed epididymal sperm was used in the other 11. We compared the fertilization capability of ICSI using frozen-thawed epididymal sperm with fresh epididymal sperm. Eleven patients became pregnant and five of these pregnancies resulted from frozen epididymal sperm. The fertilization rate per oocyte was 58% with fresh sperm, and 66% with frozen-thawed sperm. The rate of clinical pregnancy for one embryo transfer was 46% with fresh sperm, and 45% with frozen-thawed sperm. There were no significant differences between fresh and frozen-thawed spermatozoa in the fertilization rate of oocytes or the clinical pregnancy rate. Our results suggest that we should cryopreserve supernumerary spermatozoa during a MESA/ICSI procedure in order to avoid repeated scrotal surgery.

A variant of Saccharomyces cerevisiae pep4 strain with improved oligotrophic proliferation, cell survival and heterologous secretion of alpha-amylase

A variant of Saccharomyces cerevisiae pep4 strain 20B12, with improved oligotrophic proliferation, cell survival and secretion of heterologous mouse alpha-amylase, is described. Previously we reported a procedure to enrich NI transformants that are not inhibited by cytotoxic expression of hepatitis B virus surface antigen in the secretion pathway of the protease-A-deficient (pep4) strain. To use the NI cells as a host for heterologous expression, we tried to amend the introduced pYAS/12S vector and obtain a host strain, NI-C, with stable NI phenotype and trp1 marker restored. Southern analysis of genomic DNA of NI-C suggested that the original pYAS/12S was abnormally rearranged and not completely corrected. Further assay showed that the viability and mitotic ability of the NI-C strain were increased. While using the NI-C strain as host for plasmid transformation and heterologous expression of mouse alpha-amylase, we observed that transformed colonies grew more quickly and secreted more alpha-amylase than general yeast strains. A further test showed that the NI-C strain was able to use mouse alpha-amylase as a positive selection marker to form transformed colonies on nitrogen-starved plates that contain starch as the sole carbon source. The results imply that the NI-C variant is an improved pep4 strain that can be used for heterologous expression and for the development of new selective markers in the yeast transformation system.

A high prevalence of p53 mutations in pre-malignant oral erythroplakia

Oral squamous-cell carcinoma is thought to be preceded by a number of precursor stages which induce morphological changes in cells of the oral mucosa resulting in clinically detectable pre-malignant lesions such as erythroplakia or leukoplakia. To better understand the etiology of oral erythroplakia, we have examined the p53 tumor-suppressor gene (exons 5-9) for mutations in 24 oral erythroplakia lesions of varying dysplastic phenotypes by PCR/single-strand conformational polymorphism and direct DNA-sequencing analyses. A total of 12 p53 mutations were detected in 11 of 24 (46%) erythroplakia specimens (one specimen contained two different p53 mutations); 25% were single-base-pair deletions and 33% were either G:C-->T:A transversions or G:C-->A:T transitions. A high prevalence of p53 mutation was observed in all categories of erythroplakia lesions: 33% for mildly dysplastic lesions, 50% for lesions exhibiting moderate to severe dysplasia and 50% for lesions that were carcinoma in situ. Although the combined prevalence of p53 mutations observed in erythroplakia was significantly higher (p = 0.02) than that observed earlier for leukoplakia, the prevalence of p53 mutations was similar in erythroplakia and leukoplakia specimens from smokers. The prevalence and spectrum of p53 mutations observed in this series of erythroplakia lesions are similar to those observed for oral squamous-cell carcinoma. These results indicate that mutations of the p53 gene may be linked to the high malignant potential of erythroplakia and provide further evidence that p53 mutation may be an early event in the genesis of oral squamous-cell carcinoma.

The significance of soluble interleukin-2 receptor in monitoring disease relapse in patients with nasopharyngeal cancer

BACKGROUND

Soluble interleukin-2 receptor alpha (sIL-2R alpha) is a well-known indicator of T-cell activation noted to be increasing in nasopharyngeal cancer. However, the significance of sIL-2R alpha in monitoring disease relapse is unclear. This study was initiated to address this issue.

METHODS

Serum of 56 patients with NPC, which underwent either primary, salvage, or palliative treatments, from 1992 to 1993 at the Cancer Center, Veterans General Hospital-Taipei, were collected from our serum bank. According to their disease status at the time of study, at least two years after last treatments, the 56 patients were divided into four groups. The remission group represented those in remission at the time of study (n = 24). The metastasis group represented those with distant metastasis present at the time of study (n = 17). The recurrence group represented those with locoregional recurrence present at the time of study (n = 11). The combined group represented those with locoregional recurrence as well as distant metastasis (n = 4). The seral sIL-2R alpha concentrations of the 56 NPC patients were determined with enzyme-linked immunoabsorbent assay. The combined group was excluded in our statistical analysis. We performed statistical analysis on the differences of paired serum sIL-2R alpha concentrations between different periods of the diseases. The first analysis was on the differences of sIL-2R alpha concentrations between diagnosis and post-radiotherapy periods for 13 out of 24 patients in the remission group and 7 out of 11 patients in the recurrence group. The second analysis was on the differences of sIL-2R alpha concentration between follow-up before detection-of-relapse and after detection-of-relapse for 5 out of 17 patients in the metastasis group and six out of 11 patients in the recurrence group.

RESULTS

The first statistical analysis revealed no significant differences of sIL-2R alpha concentrations for the remission group (P = 0.946) and the recurrence group (P = 0.156) between diagnosis and post-radiotherapy periods. The second statistical analysis revealed no significant differences of sIL-2R alpha concentrations between before and after detection-of-relapse for the recurrence group, neither (P = 0.438). The results for the metastasis group were different. The sIL-2R alpha concentrations were shown to increase after the detection of metastasis for the 5 paired samples from the metastasis group, although the Wilcoxon signed ranks test on the differences only showed borderline significance (P = 0.063).

CONCLUSIONS

Our findings show that sIL-2R alpha would be of no value in monitoring the development of locoregional recurrence but might be useful in monitoring distant metastasis. Although our current limited data did not provide strong support for the role of sIL-2R alpha in monitoring metastasis, it might be delineated in the future by collecting more data.

Anti-HIV type 1 activity of wild-type and functional defective RANTES intrakine in primary human lymphocytes

We have developed a genetic "intrakine" strategy to inactivate the CC-chemokine receptor 5 (CCR-5), the principal coreceptor for macrophage (M)-tropic HIV-1 viruses (Yang et al, 1997). The inactivation of CCR5 was achieved by targeting a modified CC-chemokine (RANTES) to the lumen of the endoplasmic reticulum (ER) to block the transport of the newly synthesized CCR-5. The transduced lymphocytes with the phenotypic CCR5 knockout were shown to be resistant to M-tropic HIV-1 infection. This study illustrated the feasibility of the intrakine strategy to block HIV-1 infection. In our current study, the potential clinical application of the intrakine approach was further evaluated in human peripheral blood lymphocytes (PBLs). PBLs were transduced with the RANTES intrakine gene by using retroviral vectors with the truncated low-affinity human nerve growth factor receptor (deltaNGFR) marker, and then isolated by an anti-NGFR antibody/magnetic bead method. The surface expression of CCR-5 in the transduced lymphocytes was dramatically inhibited, as demonstrated by flow cytometric assays. The transduced PBLs were shown to resist various types of M-tropic HIV-1 virus infection. The cell viability, cell proliferation rates, and cell surface markers of the intrakine-transduced PBLs were shown to be comparable to those of control PBLs. The transduced PBLs were also found to respond to the stimulation of various CXC- and CC-chemokines, other than RANTES. The transduced PBLs responded to tetanus antigen stimulation by increasing IL-2 production and cell proliferation. In addition, a functionally defective mutant of RANTES that retains its binding activity to CCR-5, but loses its signaling ability, was used to generate a mutant RANTES intrakine. The primary lymphocytes transduced with the mutant RANTES intrakine were found to be resistant to M-tropic HIV-1 infection. From these results, we conclude that the primary human lymphocytes transduced with either the wild-type or functionally defective RANTES intrakine are resistant to M-tropic HIV-1 infection, and maintain their basic biological functions. This study, therefore, indicates the potential clinical application of the intrakine approach for HIV-1 gene therapy.

Genetic co-inactivation of macrophage- and T-tropic HIV-1 chemokine coreceptors CCR-5 and CXCR-4 by intrakines

CC-chemokine receptor (CCR)-5 is the principal coreceptor for the entry of macrophage (M)-tropic HIV-1 viruses into a cell, while CXC-chemokine receptor (CXCR)-4 is the principal coreceptor for T cell line (T)-tropic HIV-1. In this study, we utilized a novel intracellular chemokine (intrakine) strategy to co-inactivate genetically both CCR-5 and CXCR-4 in human lymphocytes. The principle of co-inactivation of CCR-5 and CXCR-4 was illustrated by targeting the CC-intrakine and CXC-intrakine to the lumen of the endoplasmic reticulum (ER) for intracellular blockade of the transport of newly synthesized chemokine coreceptors to the cell surface. The lymphocytes with the phenotypic knock-out of CCR-5 and CXCR-4 were found broadly to resist the infection of M-tropic, T-tropic and dual-tropic HIV-1 viruses. Moreover, the transduced lymphocytes retained normal cell features, including the responsiveness to mitogen and recall antigen stimulation. Thus, this study to our knowledge, is the first to demonstrate that genetic co-inactivation of the M- and T-tropic HIV-1 principal coreceptors in lymphocytes or other cells could be a viable strategy for the long-term control of HIV-1 infection.

Markers of cell proliferation in normal epithelia and dysplastic leukoplakias of the oral cavity

The expression of several markers of epithelial cell proliferation was analyzed to establish baseline data for future chemoprevention studies of oral premalignant lesions. Punch biopsies (n = 60) from three different sites of oral mucosa (bucca, lateral tongue, and the floor of the mouth) were obtained from 20 normal donors of both sexes. After formaldehyde fixation and paraffin embedding, immunohistochemistry was used to detect the proliferation markers Mib-1, cyclin D1, and centromere-associated protein CENP-F. Analysis of sections stained for the three markers showed similar patterns, i.e., a low labeling index (LI) in the basal layer and a high LI in the parabasal layer at all three intraoral sites. No proliferative activity was seen above the parabasal layer (superficial layer). All sites showed similar Mib-1 LI values for the proliferative markers. The tongue epithelium exhibited higher parabasal LIs of cyclin D1 and CENP-F than did the other two sites. No significant differences were detected between smokers and nonsmokers. The data from normal mucosa were compared with those from low (n = 30)- and high (n = 17)-grade dysplastic leukoplakias. The Mib-1 LI showed a very significant change, with a 9-fold increase in the basal layer LI in dysplastic leukoplakias. Cyclin D1 and CENP-F showed similar trends with increments of up to 7-fold in the basal layer of high-grade dysplasia. Although the proliferative activity of the parabasal layer was similar in normal and leukoplakic epithelia, the superficial layer showed a significant increment in proliferative activity mainly in high-grade leukoplakia. These studies suggest that proliferation markers in the basal and superficial cells of premalignant lesions may serve as surrogate end point biomarkers for chemoprevention trials.