The pathogenesis of Schmorl’s nodes

We examined the pathogenesis of Schmorl’s nodes, correlating the histological findings from 12 lumbar vertebrae with the corresponding conventional radiographs, tomographs, MR images and CT scans. The last revealed round, often multiple cystic lesions with indistinct sclerotic margins beneath the cartilaginous endplate. The appearances are similar to the typical CT changes of osteonecrosis. Histological examination of en-bloc slices through Schmorl’s nodes gave clear evidence of subchondral osteonecrosis. Beneath the cartilage endplate, we found fibrosis within the marrow cavities with the disappearance of fat cells. Osteocytes within bone trabeculae were either dead or had disappeared. We suggest that Schmorl’s nodes are the end result of ischaemic necrosis beneath the cartilaginous endplate and that herniation into the body of the vertebra is secondary.

A stereological study of the effects of experimental inguinal cryptorchidism and subsequent orchiopexy on spermatogenesis in adult monkeys

Our previous study demonstrated that experimental intra-abdominal cryptorchidism in adult rabbits for 13 weeks resulted in severe spermatogenic arrest: type A spermatogonia was the only germ cell type seen in the seminiferous epithelium and its number per testis was reduced by 84%. Seven weeks following orchiopexy, the type A spermatogonial number returned to the near-normal range in most animals and spermatogenesis partially recovered (Reproduction 2002, 124, 95-105). This study aimed to determine whether inguinal cryptorchidism would produce less-severe damage to spermatogenesis and whether subsequent orchiopexy would better restore spermatogenesis. Five normal adult male rhesus monkeys (Macaca mulatta) underwent bilateral artificial inguinal cryptorchidism. Half a year later, one testis together with the ipsilateral epididymis were removed from each animal and then unilateral orchiopexy was performed on the contralateral side, with the remaining testis and epididymis being removed another half a year later. A contemporary unbiased and efficient stereological tool, the optical disector, was used to estimate numbers of all types of spermatogenic cells in the testis and spermatozoa in the epididymis. Spermatogenic arrest was induced by cryptorchidism at the stage of spermatogonia (n = 1), spermatocytes (n = 2) or early spermatids (n = 1), with the type A spermatogonial numbers per testis being reduced to 14.8-57.2% of the control average; in one of the five cryptorchid animals, however, spermatogenesis remained normal. Subsequent orchiopexy, which was successfully performed on two animals with cryptorchidism-induced spermatogenic arrest, brought on a full or partial recovery of spermatogenesis. In conclusion, inguinal cryptorchidism induces less severe (in comparison with an intra-abdominal one) and variable damage to spermatogenesis, which is restored, at least in part, by subsequent orchiopexy.

Putative functional characteristics of human estrogen receptor-beta isoforms

Estrogen receptors (ERalpha and ERbeta) are clearly multifaceted in terms of structure and function. Several relatively abundant ERbeta isoforms have been identified, which can be differentially expressed in various tIssues. In order to provide insight into the possible role of the ERbeta family in breast tIssue a study of the putative functions of the human (h) ERbeta1, hERbeta2 and hERbeta5 isoforms was undertaken. Only hERbeta1 was found to bind ligand, which induced conformational changes as determined by protease digestion assays. All ERbeta isoforms could bind to and bend DNA although the relative efficiency with which they bound DNA differed with hERalpha>hERbeta1>hERbeta2>>hERbeta5. All ERbeta isoforms inhibited ERalpha transcriptional activity on an estrogen-response element (ERE)-reporter gene. The relative activities were hERbeta1>hERbeta2>hERbeta5; however, only hERbeta1 had transcriptional activity of its own. Both LY117018-hERalpha and LY117018-hERbeta1 complexes alone could activate transcription on a TGF-beta3-CAT gene. Although hERbeta2 and hERbeta5 had no activity alone, they inhibited ERalpha but not hERbeta1 transcriptional activity of transforming growth factor (TGF)-beta3-CAT. In marked contrast to activity on an ERE-CAT reporter gene, hERbeta1 did not modulate ERalpha transcriptional activity on a TGF-beta3-CAT reporter gene. These data support promoter-specific differential activities of hERbeta isoforms with respect to models of ERalpha regulated gene expression, and suggest that they may have a role in differentially modulating estrogen action.

Development of an Ad7 cosmid system and generation of an Ad7deltaE1deltaE3HIV(MN) env/rev recombinant virus

A strategy to circumvent immune responses to adenovirus (Ad) resulting from natural infection or repeated vector administrations involves sequential use of vectors from different Ad serotypes. To further develop an Ad-HIV recombinant AIDS vaccine approach, a replication-defective recombinant Ad from a non-subgroup C virus was required. Using a cosmid system, we generated an Ad7deltaE1deltaE3HIV(MN) env/rev recombinant virus and compared expression of the inserted HIV genes with a similarly constructed replication-competent Ad7deltaE3HIV(MN)env/rev recombinant. Ad7deltaE1deltaE3HIV(MN)env/rev expressed both HIV env and rev gene products. The envelope protein was correctly processed and functional, mediating syncytia formation of Ad7deltaE1deltaE3HIV(MN) env/rev-infected cells and CD4(+) T lymphocytes. Ad7deltaE1deltaE3HIV(MN)env/rev could be amplified on 293-ORF6 cells, containing the E4 ORF6 gene, shown earlier to support production of an Ad7 vector lacking the E1a gene. The utility of this cell line is now extended to the production of replication-defective Ad7 recombinants lacking E1a, E1b, and protein IX genes. Sequential immunizations with Ad-HIV recombinants based in different Ad serotypes have been shown to effectively elicit both humoral and cellular HIV-specific immune responses. The recombinant Ad7deltaE1deltaE3HIV(MN)env/rev will be useful in such AIDS vaccine strategies. Further, these studies have created new cosmid vectors that can be applied to generation of single- or double-deleted Ad7 recombinants with foreign genes inserted into the E1 and/or E3 regions.

Quantitative (stereological) study of the effects of vasectomy on spermatogenesis in rhesus monkeys (Macaca mulatta)

Vasectomy reversal by vasovasostomy after long-term vasectomy in men results in lower sperm counts and pregnancy rates compared with controls, and severe damage to spermatogenesis has been observed in some animal models such as mice. The primary aim of this study was to evaluate, using sophisticated stereological methods, whether vasectomy of 6 and 12 months in a non-human primate would lead to, among other morphometric changes, reduced numbers of germ cells in testes and spermatozoa in epididymides. Five normal adult male rhesus monkeys (Macaca mulatta) underwent bilateral vasectomy, with another three aged-matched normal monkeys not undergoing vasectomy. One testis together with the ipsilateral epididymis was removed from each animal at 6 months, and the other testis and epididymis, the prostate gland and seminal vesicles were removed at 12 months. Various morphometric data were obtained using stereological methods and an unbiased and efficient stereological tool, the optical disector, was used to estimate nuclear numbers of all types of spermatogenic cells in testes and spermatozoa in epididymides using methacrylate-embedded sections 25 microm in thickness. As shown by a two-way repeated measures analysis of variance, vasectomy or hemicastration (removal of the organs at 6 months) had no significant effects on all quantitative parameters of stereology obtained from the testis, epididymis, prostate gland and seminal vesicle, except that (i) sperm granuloma was observed from three of five vasectomized animals both at 6 and 12 months, and (ii) hemicastration significantly reduced the diameter of the seminiferous tubules and increased the number of type A spermatogonia per testis. In conclusion, vasectomy in the non-human primate is a safe procedure in terms of effects on the structures of the reproductive organs.

A DNA vaccine encoding a cell-surface protein antigen of Streptococcus mutans protects gnotobiotic rats from caries

A cell-surface protein antigen (PAc) of Streptococcus mutans is considered a virulence factor because it may mediate initial attachment of Streptococcus mutans to tooth surfaces. Thus, inhibiting PAc is predicted to provide protection against caries. To develop vaccines against dental caries, we constructed a DNA vaccine, pCIA-P, which encodes two high-conservative regions of PAc. Expression of the recombinant protein was obtained in eukaryotic cells in vitro and in vivo. In this report, we provide evidence that fewer caries lesions, and high levels of PAc-specific salivary IgA antibody and serum IgG antibody, were observed in gnotobiotic rats following targeted salivary gland (TSG) administration of pCIA-P. This study shows that the recombinant DNA vaccine pCIA-P could induce protective anti-caries immune responses and that TSG immunization is a promising strategy for the inhibition of dental caries.

Molecular dissection of seedling-vigor and associated physiological traits in rice

seedling-vigor is important for crop establishment. There have been reported quantitative trait locus (QTL) analyses on seedling-vigor related morphological traits. However, physiological understanding of these detected QTLs is rather limited. In this study, we employed a recombinant inbred population to detect QTLs for seedling-vigor traits and physiological traits related to seedling-vigor. Germination rate and seedling growth were measured to quantify seedling-vigor. Total amylase activity, alpha-amylase activity, reducing sugar content, root activity and seed weight were determined. Correlations were observed between the seedling-vigor and physiological traits. QTL analysis reveals that the intervals of RG393-C1087-RZ403 on chromosome 3, C246-RM26-C1447 and R830-R3166-RG360-C734b on chromosome 5, and the interval of Waxy on chromosome 6 are the four main chromosomal regions controlling seedling-vigor. Several QTLs for amylase activities, reducing sugar content and root activity were localized in the similar regions as the QTLs for seedling-vigor. The results suggest that these traits were under the control of pleiotropic and/or closely linked QTLs. The implications of the results in the understanding of the physiological basis of seedling-vigor were discussed.

A quantitative (stereological) study of the effects of experimental unilateral cryptorchidism and subsequent orchiopexy on spermatogenesis in adult rabbit testis

The aim of this study was to examine the controversial effects of experimental unilateral cryptorchidism and subsequent orchiopexy on the number of germ cells and other morphometric characteristics of testicular and epididymal structures in adult rabbits. Unilateral cryptorchidism was induced in 11 mature male New Zealand white rabbits by returning one testis, together with the ipsilateral epididymis, to the abdominal cavity via a surgical procedure. After 3 months, testes and epididymides were removed from six animals (and from six age-matched control animals that did not undergo the surgery). Orchiopexy was performed on the five remaining animals and the testes and epididymides of these animals (and an additional six age-matched control animals) were removed 7 weeks later. A contemporary, unbiased and efficient stereological tool, the optical disector, was used to estimate the number of nuclei in the testis and epididymis using methacrylate-embedded sections of 25 micron in thickness. Cryptorchidism resulted in severe testicular atrophy and spermatogenic arrest: type A spermatogonia and Sertoli cells only were seen in the seminiferous epithelium, and the number of type A spermatogonia per testis was reduced by 84%. After orchiopexy, the testis remained atrophied and the number of type A spermatogonia returned to the near-normal range in four of five animals, but spermatogenesis was recovered only partially at the stage of early primary spermatocytes (one animal), late primary spermatocytes (two animals) or spermatids (one animal). In conclusion, cryptorchidism caused severe spermatogenic arrest that was potentially recoverable (in view of the restoration of the number of type A spermatogonia), but orchiopexy failed to induce full recovery of spermatogenesis.

Mortality in 7B2 null mice can be rescued by adrenalectomy: involvement of dopamine in ACTH hypersecretion

The serine protease prohormone convertase 2 (PC2), principally involved in the processing of polypeptide hormone precursors in neuroendocrine tissues, requires interaction with the neuroendocrine protein 7B2 to generate an enzymatically active form. 7B2 null mice express no PC2 activity and release large quantities of uncleaved ACTH, resulting in a lethal endocrine condition that resembles pituitary Cushing's (Westphal, C. H., Muller, L., Zhou, A., Bonner-Weir, S., Schambelan, M., Steiner, D. F., Lindberg, I. & Leder, P. (1999) Cell 96, 689). Here, we have compared the 7B2 and PC2 null mouse models to determine why the 7B2 null, but not the PC2 null, exhibits a lethal disease state. Both 7B2 and PC2 nulls contained highly elevated pituitary adrenocorticotropic hormone (ACTH); the neurointermediate lobe content of ACTH in 7B2 nulls was 13-fold higher than in WT mice; that of the PC2 null was 65-fold higher. However, circulating ACTH levels were much higher in the 7B2 null than in the PC2 null. Because hypothalamic inhibitory dopaminergic control represents the major influence on intermediate lobe proopiomelanocortin-derived peptide secretion, dopamine levels were measured, and they revealed that 7B2 null pituitaries contained only one-fourth of WT pituitary dopamine. Adrenalectomized 7B2 null animals survived past the usual time of death at 5 weeks; a month after adrenalectomy, they exhibited normal levels of pituitary dopamine, circulating ACTH, and corticosterone. Elevated corticosterone, therefore, seems to play a central role in the lethal phenotype of the 7B2 null, whereas a 7B2-mediated dopaminergic deficiency state may be involved in the actual ACTH hypersecretion phenomenon. Interestingly, adrenalectomized 7B2 nulls also developed unexpectedly severe obesity.

Induction of genotoxic damage is not correlated with the ability to methylate arsenite in vitro in the leukocytes of four mammalian species

Arsenic is a natural drinking water contaminant that impacts the health of large populations of people throughout the world; however, the mode or mechanism by which arsenic induces cancer is unclear. In a series of in vitro studies, we exposed leukocytes from humans, mice, rats, and guinea pigs to a range of sodium arsenite concentrations to determine whether the lymphocytes from these species showed differential sensitivity to the induction of micronuclei (MN) assessed in cytochalasin B-induced binucleate cells. We also determined the capacity of the leukocytes to methylate arsenic by measuring the production of MMA [monomethylarsinic acid (MMA(V)) and monomethylarsonous acid (MMA(III))] and DMA [dimethylarsinic acid (DMA(V)) and dimethylarsonous acid (DMA(III))]. The results indicate that cells treated for 2 hr at the G(0) stage of the cell cycle with sodium arsenite showed only very small to negligible increases in MN after mitogenic stimulation. Treatment of actively cycling cells produced induction of MN with increasing arsenite concentration, with the human, rat, and mouse lymphocytes being much more sensitive to MN induction than those of the guinea pig. These data gave an excellent fit to a linear model. The leukocytes of all four species, including the guinea pig (a species previously thought not to methylate arsenic), were able to methylate arsenic, but there was no clear correlation between the ability to methylate arsenic and the induction of MN.

[Clinical comparison between intraoperative local arterial infusion chemotherapy and systemic venous chemotherapy of gastric cancer]

OBJECTIVE

To evaluate the effect of intraoperative local arterial infusion chemotherapy for gastric cancer.

METHODS

The effects of intraoperative local arterial infusion chemotherapy in 40 patients with gastric cancer were assessed. Twenty-four patients with gastric cancers who underwent the intraoperative systemic chemotherapy were taken as controls. The removed specimens were examined microscopically to show the degeneration and necrosis of the tumour cell.

RESULTS

After the treatment of the tumour cells, all of the cases in the study group showed various degrees of degeneration and necrosis. The immediate effective rate was 95% for the the study group but only 41.67% for the control group (P < 0.05).

CONCLUSION

Intraoperative local arterial infusion chemotherapy for gastric cancer has good immediate effect and little side effect; it prevents the intraoperative iatrogenic metastases and implantation and decreases the postoperative recurrence of gastric cancer.

[The effect of salvia miltiorrhiza and shengmai on inflammatory mediator and renal function of post-operative patients with obstructive jaundice]

OBJECTIVE

To investigate the effect of salvia miltiorrhiza and shengmai (SS) on inflammatory mediator and renal function in patients with obstructive jaundice (OJ).

METHODS

This study included three groups: the OJ patients receiving SS for 6 days after operation (the SS group, n = 15); the OJ patients not receiving SS (the OJ group, n = 15); the patients with other hepato-biliary disorders (the Non-OJ group, n = 15). The levels of ET, LPs, TNF-alpha, IL-6, IL-8 and urine RBP, TFR, ALB were measured one day before operation and 1, 4, 7 days after operation.

RESULTS

The SS group's LPs, TNF-alpha, IL-6, IL-8, ET, RBP, TFR and ALB levels were obviously lower on Day 7 after operation as compared with those on Day 1 after operation (P < 0.05). The urine RBP and ALB levels were significantly lower in the SS group than in the OJ group (P < 0.05).

CONCLUSION

The post-operative use of salvia miltiorrhiza and shengmai for patients with obstructive jaundice may effectively decrease the postoperative levels of plasma LPs, ET, TNF-alpha, IL-6 and IL-8. At the same time, salvia miltiorrhiza and shengmai may protect renal function by inhibiting inflammatory mediator and improving blood dynamics.

Deletion of N-terminal myristoylation site of HIV Nef abrogates both MHC-1 and CD4 down-regulation

HIV-1 Nef is a desirable vaccine component because it is expressed early and abundantly during HIV infection, and contains many CTL, T-helper cell, and B-cell epitopes. Nef, however, down-regulates MHC-1 and CD4 cell surface expression, contributing to viral escape from host immunity. To prevent Nef from down-regulating both MHC-1 and CD4 while preserving most CTL epitopes, a panel of Nef mutants was constructed and assessed. Some mutants, as expected, modulated either MHC-1 or CD4 expression. Others prevented down-regulation of both proteins but sacrificed numerous immunogenic epitopes. Deletion of 19 N-terminal amino acids including the myristoylation signal from Nef completely abrogated both MHC-1 and CD4 down-regulation while preserving most CTL, T-helper and B-cell epitopes. Our results demonstrate that the myristoylation signal in the Nef protein is critical for Nef-mediated endocytosis of both MHC-1 and CD4. Non-myristoylated Nef containing a full complement of CTL epitopes has greater potential as a vaccine component than wild-type Nef.

[Immunolocalization of laminin during reparative dentinogenesis]

OBJECTIVE

To investigate the immunolocalization of laminin in the process of dental pulp injury and repair.

METHODS

One cavity was prepared on the mesial surface of the first molars of Wistar rats. The animals were sacrificed in 3, 15, and 30 days of post-operation. After histological process, the paraffin sections were reacted with monoclonal antibodies against rat laminin using SABC method.

RESULTS

Immunolocalization demonstrated positive staining for laminin in the different stages of dental pulp repair. In 3 days group, no reparative dentin were observed. The positive staining was located in odontoblasts and in predentin. After 15 days, reparative dentin and odontoblasts were observed. The odontoblast like cells and dental pulp cells were stained positively. 30 days later, the stronger staining intensity was observed in odontoblast like cells, pulp cells and in reparative dentin. Immunological reaction was particularly located among the interface of reparative dentin and dental pulp.

CONCLUSION

The localization feature of laminin suggested that laminin may be a favored factor for the adhesion of dental pulp cell during reparative dentinogenesis.

Altered processing of pro-orphanin FQ/nociceptin and pro-opiomelanocortin-derived peptides in the brains of mice expressing defective prohormone convertase 2

The bioactivity of neuropeptides can be regulated by a variety of post-translational modifications, including proteolytic processing. Here, gene-targeted mice producing defective prohormone convertase 2 (PC2) were used to examine the post-translational processing of two neuroendocrine prohormones, pro-opiomelanocortin (POMC) and pro-orphanin FQ (pOFQ)/nociceptin (N), in the brain. Reversed-phase HPLC and gel-exclusion chromatography were combined with specific radioimmunoassays to analyze the processing patterns of these two prohormones in the hypothalamus and the amygdala. In the case of POMC, the lack of PC2 activity completely prevented carboxy-shortening of beta-endorphins and greatly diminished conversion of beta-lipotropin to gamma-lipotropin and beta-endorphin. Although conversion of beta-lipotropin to beta-endorphin decreased, the lack of PC2 activity caused an increase in beta-lipotropin and beta-endorphin levels in the mutant animals, but no increases in POMC or biosynthetic intermediates were seen. The extent of OFQ/N production was significantly lower in PC2-deficient mice and there was an accumulation of relatively large amounts of pOFQ/N and biosynthetic intermediates. These results demonstrate that PC2 is directly involved in the biogenesis of two brain neuropeptides in vivo and suggest that the specific prohormone and cellular context influences neuropeptide processing by PCs.

Experiences from a school-based oral health promotion programme in Wuhan City, PR China

OBJECTIVES

To evaluate the effect of a six-year oral health promotion programme for school children of Wuhan City, PR China.

METHODS

The programme group (P-group) comprised 233 children who had just entered grade 1 (1989). The programme provided an oral health promotion programme, and 215 12-year-old children from three schools participated as a control group (C-group). After the 6-year period of the programme (1995), all of the children had a clinical examination according to the criteria of the WHO and responded to a structured questionnaire on dental health behaviour.

RESULTS

The results showed that attitudes to dental care, regular tooth brushing habits, use of fluoridated toothpaste, gingival health and dental visits, frequencies of consuming sugary drinks/foods were improved in the p-group when compared with the C-group.

CONCLUSION

The school-based oral health promotion programme should be expanded.

Genotoxicity studies of three triazine herbicides: in vivo studies using the alkaline single cell gel (SCG) assay

Triazine herbicides are prevalent contaminants of groundwater in the agricultural regions of the United States. The literature on the genotoxicity of triazines is rife with conflicting data, though the general tendency is for most studies to report negative results. In order to investigate further the genotoxicity of triazines, we exposed mice to triazines by intraperitoneal injection up to the maximum tolerated doses. About 24h later, blood was removed, and the leukocytes subjected to DNA damage analysis using the alkaline single cell gel electrophoresis assay (SCG), one of the most sensitive DNA damage assays available. Our results indicate that atrazine induced a small dose-related increase in DNA damage. Simazine did not induce any dose-related increase in DNA damage. Cyanazine induced a marginal increase in DNA damage with dose, but no individual dose was significantly increased compared to the control. These results indicate that these triazines, even at extremely high concentrations, have only marginal DNA-damaging activity in vivo in mouse leukocytes.

Efficacy and safety of a specific inhibitor of the BCR-ABL tyrosine kinase in chronic myeloid leukemia

BACKGROUND

BCR-ABL is a constitutively activated tyrosine kinase that causes chronic myeloid leukemia (CML). Since tyrosine kinase activity is essential to the transforming function of BCR-ABL, an inhibitor of the kinase could be an effective treatment for CML.

METHODS

We conducted a phase 1, dose-escalating trial of STI571 (formerly known as CGP 57148B), a specific inhibitor of the BCR-ABL tyrosine kinase. STI571 was administered orally to 83 patients with CML in the chronic phase in whom treatment with interferon alfa had failed. Patients were successively assigned to 1 of 14 doses ranging from 25 to 1000 mg per day.

RESULTS

Adverse effects of STI571 were minimal; the most common were nausea, myalgias, edema, and diarrhea. A maximal tolerated dose was not identified. Complete hematologic responses were observed in 53 of 54 patients treated with daily doses of 300 mg or more and typically occurred in the first four weeks of therapy. Of the 54 patients treated with doses of 300 mg or more, cytogenetic responses occurred in 29, including 17 (31 percent of the 54 patients who received this dose) with major responses (0 to 35 percent of cells in metaphase positive for the Philadelphia chromosome); 7 of these patients had complete cytogenetic remissions.

CONCLUSIONS

STI571 is well tolerated and has significant antileukemic activity in patients with CML in whom treatment with interferon alfa had failed. Our results provide evidence of the essential role of BCR-ABL tyrosine kinase activity in CML and demonstrate the potential for the development of anticancer drugs based on the specific molecular abnormality present in a human cancer.

[Inflammatory mediator in patients with obstructive jaundice and its effect on renal function]

OBJECTIVE

To investigate the effect of inflammatory transmitter on renal function in obstructive jaundice.

METHODS

15 patients with obstructive jaundice (OJ) as the experimental group and 15 non-joundiced patients as the control group were involved in this study. The plasma ET, LPS, TNF-alpha, IL-6, IL-8 and urine REP, TFR, ALB were measured in 15 patients with OJ before and 1, 4, 7 days after surgery and in 15 patients without jaundice as controls.

RESULTS

The levels of plasma ET, LPS, TNF-alpha, IL-6, IL-8 and urine RBP, TFR, ALB increased significantly at multiple time points as compared with those in the non-OJ patients (P < 0.05), and the changes of plasma ET, LPS, TNF-alpha, IL-6, IL-8 are the same as those of urine RBP, TFR, ALB.

CONCLUSION

These data suggest that there is interaction between ET, LPS, TNF-alpha, IL-6, IL-8 and the damage to renal function with OJ after surgery.

The relationship between cartilage end-plate calcification and disc degeneration: an experimental study

OBJECTIVE

To study the relationship between cartilage end-plate calcification and intervertebral disc degeneration.

METHODS

An experimental model of cervical disc degeneration in rabbits was established by resection of the cervical supraspinous and interspinous ligaments and detachment of the posterior paravertebral muscles from the cervical vertebrae. Mechanical instability in the cervical spine elicited by this surgical intervention accelerated the process of intervertebral disc degeneration. The extent of intervertebral disc degeneration was graded in morphologically, and the thicknesses of the calcified layer and the uncalcified layer of the cartilage end-plate were measured in each degenerated cervical disc.

RESULTS

In less severely degenerative cervical discs, the morphology of the cartilage end-plate showed nearly normal construction, and the tidemark was clear. In severely degenerative discs, the matrix and cells showed fibrosis, the tidemark advanced, and the calcified cartilage thickened. There exists a positive correlation between the thickness of the calcified layer of the cartilage end-plate and the degree of cervical disc degeneration.

CONCLUSION

The calcification of the cartilage end-plate is the key factor that initiates and promotes cervical disc degeneration.

Tissue distribution and physiologically based pharmacokinetics of antisense phosphorothioate oligonucleotide ISIS 1082 in rat

The aim of this study was to develop a whole body physiologically based model of the pharmacokinetics (PBPK) of the phosphorothioate oligonucleotide (PS-ODN) ISIS 1082 in vivo. Rats were administered an intravenous (i.v.) bolus dose of ISIS 1082 (10 mg/kg plus 3H tracer), and arterial blood and tissues were taken at specific times up to 72 hours. Radioactivity was measured in all samples. The parent compound was determined specifically in blood and tissues at 90 minutes and in liver and kidney also at 24 hours, using capillary gel electrophoresis (CGE). A whole body PBPK model was fitted to the combined blood and tissue radioactivity data using nonlinear regression analysis. CGE analysis indicated that the predominant species in plasma and all tissues is ISIS 1082, together with some n-1 and n-2 metabolites. Total radioactivity primarily reflects these species. The whole body model successfully described temporal events in all tissues. However, to adequately model the experimental data, all tissues had to be partitioned into vascular and extravascular spaces to accommodate the relatively slow distribution of ISIS 1082 out of blood because of a permeability rate limitation. ISIS 1082 distributes extensively into tissues, but the relative affinity varies enormously, being highest for kidney and liver and lowest for muscle and brain. A whole body PBPK model with a permeability rate limited tissue distribution was developed that adequately described events in both blood and tissue for an oligonucleotide. This model has the potential not only to characterize the events in individual tissues throughout the body for such compounds but also to scale across animal species, including human.

[A study on the pathogenesis of Streptococcus mitis exotoxin]

OBJECTIVE

To study the isolation, purification and pathogenesis of Streptococcus mitis pyrogenic exotoxin causing toxic shock syndrome.

METHODS

Streptococcus mitis isolated from patients' throat were shaking cultivated. After being centrifuged, the supernatant fluid of the culture was precipitated with 20%, 40%, 60%, 80% (NH(4))(2)SO(4) respectively and the fast protein liquid chromatography(FPLC) was used for the final step of purification. Rabbits receiving subcutaneous injection with respective purified proteins were monitored daily for fever. The ability of the purified proteins to enhance the susceptibility of the rabbits to lethal Escherichia coli endotoxin shock is recorded, when the endotoxin was injected intravenously 4 hours after administration of 10 microg Streptococcus mitis exotoxin.

RESULTS

Only the protein precipitated by 20% (NH(4))(2)SO(4) (molecular weight is 34,000) from culture supernatant fluid was pyrogenic for rabbits (average temperature increase near 1 degrees C), and it can also cause the proliferation of rabbit splenocytes (mitogenicity). All the animals receiving subcutaneous injection of exotoxin containing purified proteins precipitated with higher concentrations of (NH(4))(2)SO(4) died within 16 approximately 29 hours after intravenous injection of the Escherichia coli endotoxin, demonstrating the enhanced susceptibility of the animals to lethal endotoxin shock. The control rabbits displayed none of these effects.

CONCLUSION

Streptococcus mitis exotoxin is a novel streptococcal pyrogenic exotoxin.

Construction and in vitro expression of Streptococcus mutans surface protein encoding DNA vaccine

DNA vaccine plasmids were constructed that encoded two highly-conservative regions of a surface protein, PAc, from the human major cariogenic bacterium, Streptococcus mutans. Antigen expression was evaluated in vitro by immunohistochemical analysis of human endothelial cells following cationic liposome-mediated transient transfection with recombinant plasmid. The results of this study provided a basis for further testing of these recombinant plasmids in primates and for efficacy testing of dental caries DNA vaccines in human volunteers in future.

Cytogenetic studies of three triazine herbicides. II. In vivo micronucleus studies in mouse bone marrow

Atrazine, simazine, and cyanazine are widely used preemergence and postemergence triazine herbicides that have made their way into the potable water supply of many agricultural communities. Although there are several contradictory genotoxicity studies in the literature, our previous in vitro studies with human lymphocytes showed that atrazine, simazine, and cyanazine did not induce sister chromatid exchanges (SCEs) or chromosome aberrations (CAs) up to the limits of solubility in aqueous medium using 0.5% dimethyl sulfoxide. To expand upon these results and to ensure that our in vitro findings could be replicated in an in vivo system, mice were treated with each triazine by two intraperitoneal injections, 24h apart. The animals were sacrificed and the bone marrow removed for micronucleus (MN) analysis, 24h after the last injection. Two to four independent trials were performed for MN analysis in polychromatic erythrocytes, and in some trials the spleen was removed, cultured, and analyzed for SCEs and CAs. None of the triazines investigated induced MN in the bone marrow, even at doses that caused significant bone marrow suppression and/or death. These results indicate that atrazine, simazine, and cyanazine are not genotoxic as measured by the bone marrow MN assay in mice following high dose exposures.