[Expression of the PAC gene of S. mutans in S. lactis]

Expression of the pac gene in S. lactis were analyzed by dot immunoblotting with rabbit anti-PAc serum. The amount of PAc produced by S. lactis HL107 (pLF107) was measured. This result indicated that a small amount of rPAc was detected in the culture supernatant and cell homogenate of S. lactis HL107 (pLF107) but not in the control strain S. lactis LM0230. The amount of rPAc in S.lacits HL107 (pLF107) was six times lower than that in S. mutans Ingbritt. Expression of cloned pac gene in S. lactis was also confirmed in this result.

Induction of c-fos expression following stimulation of pulmonary neuroendocrine cell proliferation by alterations in CO2/O-2 concentration

Pulmonary neuroendocrine (PNE) cells were harvested and cultivated from peripheral lung tissue of 15 day old fetal hamsters under selective growth conditions, including a 10% CO2 atmosphere. Following 24 h of serum starvation under 10% CO2, PNE cells placed in a 5% CO2 atmosphere failed to proliferate over the next 24 h, while cells kept at 10% CO2 showed a 2.7-fold increase in cell number. Addition of nicotine to the cell culture medium resulted in an additional concentration-dependent increase in cell number under a 10% CO2 atmosphere, while nicotine did not stimulate the proliferation of cells maintained at 5% CO2. The nicotinic receptor antagonist hexamethonium completely blocked the stimulatory effect of nicotine on cell growth. As a first step towards determining the molecular mechanisms regulating the mitogenic stimulation of PNE cells by alterations in CO2/O-2 and nicotine, cells that had been serum starved under a 10% CO2 atmosphere for 24 h were removed from the incubator and either left untreated or treated with 1 mu M nicotine under ambient air. The cells were then returned to either a 5% or 10% CO2 atmosphere. Removal of the cells from a 10% CO2 environment and subsequent reintroduction to a high CO2 concentration resulted in a 3- to 4-fold increase in c-Sos RNA expression within 15-30 min upon return to the cell culture incubator. c-fos RNA levels their decreased back to control values by 1 h. Reintroduction into a 5% CO2 atmosphere, which failed to stimulate cell growth in the proliferation assay, caused only a 2-fold increase in the levels of c-fos transcripts. The CO2-mediated increases in c-Sos transcripts were observed both in the presence and absence of nicotine, suggesting that the effects of nicotine were mediated through a fos-independent pathway. Neither the alterations in CO2/O-2 concentration or treatment with nicotine altered the levels of c-myc or c-jun gene transcripts. Nicotine thus acts indirectly but synergistically with high CO2 concentrations to stimulate PNE cell proliferation.

[Reversion of malignant phenotypes of human lung squamous carcinoma cells by ornithine decarboxylase antisense RNA]

Abnormally elevated activity of ornithine decarboxylase (ODC), with subsequent polyamine accumulation are intimately associated with the genesis, development and metastasis of cancer. Therefore, ODC antisense RNA was used to transfect human lung squmous carcinoma cell line LTEP-78. Compared with the parental cells, growth of the antisense transfected LTEP-78 cells arrested in G0/G1 phase and colony formation in soft agar and tumorigenicity in nude mice were significantly reduced. Nucleic acid hybridization demonstrated the expression of ODC antisense RNA and the content of ODC mRNA was markedly reduced. The results suggest that the reversion of malignant phenotypes of human lung squamous carcinoma cells is associated with the control of polyamine biosynthesis.

[Expression of c-myc gene and biosynthesis of biological macromolecules in antisense transfectant HLR60-9]

The recombinant plasmid PGC was constructed for transcription unit of c-myc gene with bi-direction in vitro, to make RNA probes for detection of c-myc mRNA and antisense RNA expression of transfectant HLR60-9, which was obtained from HL60 cells transfected with inducible c-myc antisense RNA expression plasmid. The results from HLR60-9 cells induced by Cd2+ indicated that expression of c-myc antisense RNA increased with Cd2+ concentration and exposure time, while c-myc mRNA expression progressively reduced. Using immunohistochemical technique no c-myc P62 protein expression was detected. The incorporation of 3H-TdR,3H-UR,3H-Leu revealed significant suppression of DNA, RNA and protein biosyntheses. It is suggested that the reversion changes previously reported in malignant phenotypes of HLR60-9 cells and the inhibition of macromolecule biosynthesis mentioned above were associated with the blockade of c-myc gene expression by its antisense RNA.

Cytotoxicity testing of poly(anhydride-co-imides) for orthopedic applications

The cytotoxicity of a series of poly(anhydride-co-imides) with osteoblast-like cells (MC3T3-E1) was evaluated. The imide component of the copolymers was based on trimellitylimidoglycine (TMA-gly), and the anhydride component was based on either sebacic acid (SA) or 1,6-bis(carboxyphenoxy)hexane (CPH). Cell adhesion and proliferation on surfaces of the polymer discs were observed by environmental scanning electron microscopy (ESEM). During the first 24 h of attachment, cells showed normal morphology when cultured on the various copolymers of CPH. Concurrently, the effects of polymer breakdown products on osteoblast-like cells were evaluated by studying their proliferation (cell numbers), viability (dye exclusion), and morphology (light microscopy). Cell cultures in the presence of these breakdown products resulted in normal morphologies and reached confluency after 7 days. This initial in vitro evaluation with osteoblast-like cells suggests that the poly(anhydride-co-imides) may be viable carriers for osteoblasts.

[Effects of gu chi san on cultured human gingival fibroblasts]

The present study demonstrates that Gu Chi San is able to increase the bone density in the clinical and animal tests. This study finds that Gu Chi San has no cytotoxicity on HGFs, and 1g/L Gu Chi San extracts can stimulate the mitosis and enhance the DNA synthesis of HGFs. The results indicate that certain substances are present in Gu Chi San.

The 5S rRNA and the rRNA intergenic spacer of the two varieties of Cryptococcus neoformans

The intergenic spacers (IGS) separating the 23S-like and 16S-like rDNAs of the two varieties of the human pathogenic fungus Cryptococcus neoformans were amplified, cloned and sequenced. The C. neoformans var. neoformans IGS was 2421 nt with 5S rRNA at positions 1228-1345 3' of the 23S-like rRNA. The C. neoformans var. gattii IGS was 2480 nt with 5S rRNA at positions 1268-1385 3' of the 23S-like rRNA. For both varieties the 5S rDNA genes were in the same orientation as the 16S-5.8-23S genes and encode a 118 nt molecule of identical sequence. Phylogenetic comparison of C. neoformans 5S rDNA with that of other fungi placed this fungus in close relationship with other basidiomycetes including Tremella mesenterica, Bullera alba, and Cryptococcus laurentii. A secondary structure model for the deduced 5S rRNA was constructed by comparative sequence analysis. Polymerase chain reaction-amplified IGS of 12 C. neoformans var. neoformans strains revealed extensive size variation ranging from 100 to 300 nt. Size variation between strains in the length of the IGS may be useful for distinguishing strains. Structurally, the IGS were characterized by the presence of occasional short direct GC-rich 19-nt repeats. Overall IGS sequence identity between the C. neoformans varieties was only 78.5%, in sharp contrast to the identical or nearly identical sequences for the rDNA genes, and suggests rapid evolution for IGS sequences.

Molecular and idiotypic analysis of antibodies to Cryptococcus neoformans glucuronoxylomannan

Antibodies to the Cryptococcus neoformans capsular glucuronoxylomannan (GXM) form the basis of two potential therapeutic intervention strategies, i.e., conjugate vaccines and passive antibody therapy. To better understand the molecular basis of the antibody response, the heavy- and light-chain immunoglobulin variable region (VH and VL, respectively) sequences of seven monoclonal antibodies (MAbs) to GXM were determined. Rabbit anti-idiotypic serum was made to the previously characterized murine MAb 2H1 and used to study MAb 2H1 idiotype expression in other GXM-binding MAbs and immune sera. MAb E1 originated from a C3H/HeJ mouse immunized with C. neoformans serotype A polysaccharide. MAbs 471, 1255, 339, 3C2, 386, and 302 originated from BALB/c mice immunized with polysaccharide of serotypes A, A, B, C, D, and D, respectively, conjugated to sheep erythrocytes. In the E1, VH uses V11 from the T15 gene family and JH3 and has a D segment of three amino acids, and the VL uses a VKSer-like gene family element and JK5. In MAbs 471 and 3C2, the VH uses VH7183-like gene family elements and JH2 and has D segments of seven amino acids, and the VL uses VK5.1 and JK1. In MAbs 1255 and 339, the VH uses VH10-like gene elements and JH4 and has six codon D segments, and the VL uses a VK21-like gene element and JK5. In MAbs 302 and 386, respectively, the VH uses VHGAM-like gene elements and JH2 and JH3 and has six and four codon D segments, and VL uses VK4/5-like gene elements and JK1.VH usage, MAb 2H1 idiotype expression, and fine specificity mapping define a minimum of three GXM epitopes which elicit protective antibodies. The results confirm that the antibody response is highly restricted, suggest a close relationship between molecular structure and serological properties, and provide insight into protein structural motifs important for GXM binding.

The 16S-like, 5.8S and 23S-like rRNAs of the two varieties of Cryptococcus neoformans: sequence, secondary structure, phylogenetic analysis and restriction fragment polymorphisms

The nucleotide sequences of the 16S-like, 5.8S and 23S-like rDNAs from the two varieties of Cryptococcus neoformans, C. neoformans var. neoformans and C. neoformans var. gattii, were determined. The rRNA locus has the typical eukaryote organization of 16S-5.8S-23S with the 16S-like and 5.8S rRNA genes separated by a 124-nucleotide spacer and the 5.8S and 23S-like rRNA genes separated by a 187-nucleotide spacer in each strain. The C. neoformans var. neoformans and C. neoformans var. gattii 16S-like, 5.8S and 23S-like rRNAs are, respectively 1802, 158, and 3358 nucleotides in length and share > 99% nucleotide sequence identity, a finding which strongly supports the present taxonomic classification of two varieties within a species. Comparative structure analysis was used to construct secondary-structure models for the deduced 16S-like and 5.8S-23S-like rRNA sequences, which are similar to those of other fungal rRNAs. The C. neoformans 16S-like and 23S-like rRNA sequences were aligned with other eukaryote sequences based on secondary and higher-order structures predicted by comparative structure analysis for phylogenetic analysis. There was good correspondence between the 16S-like and 23S-like derived phylogenetic trees. The closest known fungal relative is Trichosporon beigelii. Southern blot analysis revealed one C. neoformans strain with two types of DNA repeats coding for rRNA which differed in size by about 1000 bp. Restriction fragment length polymorphisms in the rDNA locus provide useful markers for the study of epidemiology and pathogenesis of C. neoformans infections.

[Analysis of fatty acid composition of spotted fever group rickettsiae isolated in China by gas chromatography]

In present paper, fatty acid composition of seven Chinese isolates of SFG rickettsiae and six prototype strains of SFG rickettsiae were analyzed by GC-MS. Tested prototype strains of SFG rickettsiae were R. sibirica (strains 232 and 246), R. conorii (Simko), R. rickettsi (R), R. akari (Kaplan), R. australis (W58); Chinese isolates were An-84, Se-85, W-88 (human strain), MT-84, FT-84 (D. nuttalli strain), TO-85 (ova of nuttalli) and Chinese reference strain -JH-74 (D. nuttalli). They were propagated in yolk sacs of embryonated hen eggs and purified by centrifugation in a 30%-36%-42% discontinuous renografin density gradient. The fatty acid composition of selected strains of SFG rickettsiae was analyzed by gas chromatography, and then comparison being carried out by single linkage on mini-computer. Identification of the strains was performed based on the results obtained from GC-MS. Results showed that the fatty acid profiles of all the isolates from China were quantitatively similar to that of R. sibirica and quite different from other prototype strains of SFG rickettsiae.

[Change of beta tubulin gene expression in the motoneurons of spinal cord during nerve regeneration]

After crushing the right sciatic nerve of rat, the contents of both tubulin and beta tubulin mRNA increased significantly in the ventral horns of spinal cord. Analysis of tubulin in bilateral ventral horns by SDS-PAGE showed that tubulin in the injured side increased by 17%-121% of the control side. The results of in situ hybridization indicated with the signals of hybridization with beta tubulin cDNA probes were 27%-70% higher in motoneurons of the ventral horns in the injury side than the control. Northern blotting analysis of tubulin mRNA in ventral horns also revealed an increase of tubulin gene expression.

Genotypic and antigenic identification of two new strains of spotted fever group rickettsiae isolated from China

Four isolates of spotted fever group rickettsiae isolated from ticks in China were compared with all known species and strains of spotted fever group rickettsiae by immunofluorescence assay, DNA polymerase chain reaction followed by restriction endonuclease fragment length polymorphism analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western immunoblot. The Chinese isolates belonged to three types, including a novel serotype which has not been described before. One isolate obtained from tick ova of Dermacentor nuttallii in Inner Mongolia was antigenically and genotypically identical to Rickettsia sibirica. Two isolates obtained from Dermacentor sinicus collected from Beijing were identical, different from other members of spotted fever group rickettsiae but apparently closely related to R. sibirica. HA-91, a strain isolated from Hyalomma asiaticum bv. kozlovi olenew, was antigenically and genotypically unique among spotted fever group rickettsiae, and we feel that data presented here should prompt consideration of it as a new species on the basis of current rickettsial taxonomy.

Interstitial 1.06 Nd:YAG laser thermotherapy for brain tumors under real-time monitoring of MRI: experimental study and phase I clinical trial

This paper presents the experimental and clinical results of interstitial 1.06 Nd:YAG laser thermotherapy (ILTT) for brain tumors under real-time monitoring by magnetic resonance imaging. The authors chose a laser heat source for interstitial thermotherapy of brain tumors for several important reasons: (1) Laser heat delivery is less complicated and more controlled; (2) laser effects on tissue can be tested, monitored, and controlled by MRI. A 1.064 nm Nd:YAG laser and a specially designed laser optic fiber (ILTT) were used in C.W. mode this study. The laser was used at 4 W at a C.W. mode pulse and total exposure duration was 10 minutes (total energy was 2400 joules). Temperature distribution was determined with a microprocessor-based thermometer and by the levels of the signal intensity under MRI. The relationship between the temperature and MRI signal intensity allowed exploration of the possibility of using MRI as a noninvasive temperature monitoring method. Two patients with glioblastoma and one patient with a brain metastasis were treated with this modality. The results and indications are presented and discussed.

Alteration in hypoxic pulmonary vasoconstriction during hypothermia in dogs

This study was performed to investigate the pulmonary vascular reactivity during hypothermia. It was found that the pulmonary vessels were more sensitive to alveolar hypoxia in hypothermic dogs, and that hypoxic pulmonary vasoconstriction (HPV) was enhanced, which could be inhibited by alpha 1-adrenoceptor blocker prazosin. The concentration of arterial plasma norepinephrine (NE) increased in dogs with hypothermia or in those with hypothermia plus hypoxia, but there was no significant difference between these two groups. The plasma level of 5-hydroxytryptamine (5-HT) was reduced during hypoxia in hypothermic dogs. Increase in plasma 6-keto-PGF1 alpha, which appeared in hypoxic dogs, was not observed during hypoxia in hypothermic dogs. These findings suggest that a potentiation in the sensitivity and reactivity of alpha-adrenoceptor in pulmonary vessels and a decrease in the modulation of PGI2 might be responsible for the enhancement of HPV. 5-HT seemed not to play a contributing role in the alteration of HPV.

Effect of endotoxin on hypoxic pulmonary vasoconstriction--the role of prostaglandins and leukotrienes

In this study, we observed the effect of endotoxemia on hypoxic pulmonary vasoconstriction (HPV) in dogs and explored roles played by prostaglandins and leukotrienes in this process. 5 micrograms/kg BW of E. coli endotoxin induced transient rise in pulmonary arterial pressure and pulmonary vascular resistance (PVR). 30 min after injection of endotoxin when PVR tended to decline, pulmonary vasoconstriction response to alveolar hypoxia was lost, and the ratio of TXB2 to 6-keto-PGF1 alpha decreased significantly. HPV was enhanced at 60-100 min and then returned to the control level at 2 h after injection of endotoxin. At these periods the ratio of TXB2 to 6-keto-PGF1 alpha was the same as before use of endotoxin, whereas plasma concentration of leukotrienes was markedly increased. Indomethacin could prevent the early loss of HPV, but no effect on the late increment of HPV was found. Diethylcarbamazine, which blocked the production of leukotrienes after use of endotoxin, could inhibit late increment of HPV. We concluded that the early loss of HPV was related to the vasodilator prostacyclin, and the late increment of HPV was mainly brought about by leukotrienes.

Strain difference in pulmonary vascular responsiveness to hypoxia in rats

The difference in pulmonary vascular response to hypoxia between Hilltop Sprague-Dawley (HT) rats and Wistar (W) rats was studied. Effects of inhibitor of leukotriene (LT) synthesis or prostaglandin (PG) synthesis on hypoxic pulmonary vasoconstriction (HPV) and chronic pulmonary hypertension were observed, and variations in plasma TXB2 and 6-keto-PGF1 alpha during hypoxia were determined. The results showed that in rats of both strains LTs are the major mediator of HPV, which is also mediated by vasoconstrictive PGs in HT rats, while modulated by vasodilative PGs in W rats. This might be the crucial mechanism responsible for the higher pulmonary vascular responsiveness in HT rats. Differences in the modulating effect of histamine and in the structural feature of pulmonary arteriole might be contributing factors as well.

A UHF probe for NMR micro-imaging experiments

A long solenoid is capable of producing, at least theoretically, a B1 field that is relatively more homogeneous than other known structures. This paper describes the design of a UHF probe incorporating a one-turn solenoid associated with a pair of parallel-plate transmission line feeders and presents a practical example used in a 360-MHz spectrometer for micro-imaging experiments. Numerical evaluation of the solenoid inductance using King's method for direct calculation of elliptic integrals is also included.

Shear force in angioplasty: its relation to catheter design and function

The inability to successfully position angioplasty catheters and the occurrence of complications during angioplasty procedures can, in part, be related to the shear forces generated during catheter introduction. Shear forces are the axial contact forces that the catheter system exerts on the inner arterial surfaces during advancement. The shear forces exerted by three different catheter designs (coaxial dilator, coaxial balloon, and linear extrusion) were measured in normal and atherosclerotic arteries; in modeled stenoses of variable severity, length, and compliance; and in modeled vessel angulations. The results with modeled vessels show that the linear extrusion catheter reduces the level of shear forces, particularly in narrow, long, noncompliant stenoses and in tortuous vessels. The stenotic artery results also show that the linear extrusion catheter minimizes these forces in tight lesions. The relative differences in forces are explained by the mechanism of action for each catheter. The reported occurrences of technical difficulties, complications, and long-term patency rates are then interpreted on the basis of the relative differences in measured shear forces. The results of this study combined with preliminary clinical data indicate that linear extrusion should facilitate placement and reduce associated complications.

Automatic NMR field-frequency lock-pulsed phase locked loop approach

A self-contained deuterium frequency-field lock scheme for a high-resolution NMR spectrometer is described. It is based on phase locked loop techniques in which the free induction decay signal behaves as a voltage-controlled oscillator. By pulsing the spins at an offset frequency of a few hundred hertz and using a digital phase-frequency discriminator this method not only eliminates the usual phase, rf power, offset adjustments needed in conventional lock systems but also possesses the automatic pull-in characteristics that dispense with the use of field sweeps to locate the NMR line prior to closure of the lock loop.