Effect of early exposure on the integration of dental implants: Part 2--Clinical findings at 6 months postloading

Implant exposure during initial healing after placement has been considered important in both implant integration and postloading effects. This study evaluated the effect of early implant exposure on the clinical findings prerestoration and 6 months postrestoration. Forty-eight implants (24 CPTi and 24 Ti-13-13) were placed in maxillary and mandibular posterior sites in six baboons. Implant exposure was evaluated for 24 of the submerged implants at placement and at each weekly visit for 3 weeks after implant placement. The crestal bone level at maxillary posterior sites was measured at 6-month uncovering, and mandibular sites were measured at 3-month uncovering. All sites were again measured 6 months after restoration placement. Periotest readings were recorded at implant uncovering and again 6 months postloading. Arbitrary groupings of the Periotest values were assigned as good = -7 to -1; guarded = 0 to +2; and poor = +3 to +27. At 6 months postloading, there were no statistical differences between CPTi and Ti-13-13 for change in crestal bone height in either arch. The mean change in maxillary crestal bone height varied from a 0.59- to 1.35-mm loss. The differences between the mean exposed and nonexposed changes were not statistically significant The mean change in mandibular crestal bone height varied from a 0.25- to 0.88-mm loss. Changes in crestal bone height for nonexposed sites from 3-month implant uncovering to 6 months postloading were statistically significant at the mesial, buccal, and lingual aspects. The mean change for the nonexposed distal aspect approached significance. The differences between the mean exposed and nonexposed changes were not statistically significant. The overall percentage of maxillary implants in the good category for nonexposed sites decreased by 41% from uncovering to 6 months after loading, while no change occurred for exposed sites; the percentage of implants in the good category was comparable for early exposed and nonexposed sites (57% and 59%, respectively). At 6 months after loading, the percentage of implants in the good category was more favorable for early exposed (88%) than nonexposed sites (50%). A one-stage implant approach should provide similar postloading clinical results as the two-stage surgical approach.

Acute pancreatitis signals activation of apoptosis-associated and survival genes in mice

In experimental models of acute pancreatitis (AP), acinar cell death occurs by both necrosis and programmed cell death or apoptosis. Apoptosis is an active form of cell death associated with a tightly regulated expression of gene products that are either pro- or antiapoptotic. The aim of this study was to characterize pancreatic mRNA levels by Northern blotting analysis of apoptosis-associated genes used during the course of cerulein-induced AP in mice. Histone H3 mRNA levels were also examined as an indicator of cell proliferation. Acinar cell apoptosis was confirmed histologically. The findings show that AP modifies pancreatic mRNA levels of both pro- and antiapoptotic genes simultaneously. Pancreatic bclXL, bax, and p53 mRNA levels increased significantly in a temporal fashion during induction of AP. Pancreatic bcl-2 mRNA levels were unchanged during AP. Pancreatic mRNA levels of insulin-like growth factor-1 (IGF-1), a mitogen and cell survival factor, and its receptor (IGF-1R) also increased in a temporal fashion during induction of AP. In summary, this study indicates that acinar cell death during cerulein-induced AP in mice can occur by the apoptotic pathway. Since factors promoting and antagonistic for cell survival are activated simultaneously, regulation of acinar cell survival appears complex and dynamic during AP.

Epithelial-myoepithelial carcinoma of the nasal cavity

A 22-year-old male presented with a 1-year history of nasal obstruction due to a polypoid mass in the right nasal cavity. Histopathologic examination revealed the tumor to consist of a mixture of a trabecular structure with a double-layered arrangement of inner dark cells and outer clear cells. Immunohistochemical examination showed the clear cells to be positive for alpha-smooth muscle actin and S-100 protein. Ultrastructural examination confirmed the myoepithelial cell origin. The tumor was excised and no recurrence or metastasis was found 40 months after surgery. We describe here a rare case of epithelial-myoepithelial carcinoma arising from the nasal cavity, one of the most unusual locations.

Comparison between posterolateral fusion with pedicle screw fixation and anterior interbody fusion with pedicle screw fixation in adult spondylolytic spondylolisthesis

There have been many reports regarding various operative methods for spondylolytic spondylolisthesis. However, there have been no reports regarding the comparison between posterolateral fusion (PLF) with pedicle screw fixation (PSF) and anterior lumbar interbody fusion (ALIF) with PSF. The purpose of the current study was to compare the clinical outcomes of PLF with PSF and ALIF with PSF, and to help in the selection of treatment options. Fifty-six patients with spondylolytic spondylolisthesis who underwent PLF with PSF (group 1, 35 patients) or who underwent ALIF with PSF (group 2, 21 patients) were studied. Minimum follow-up was 2 years. Demographic variables and disease state were similar for the two groups. We studied operating time, amount of blood loss, duration of hospital stay, clinical outcomes, complications, time at which fusion was complete, fusion rate, and radiological measurements. There were no significant differences between the two groups in terms of the amount of blood loss, duration of hospital stay, back pain, radiating pain, fusion rate, or complication rate. However, in group 2, the operation time and the time at which fusion became complete was longer, and in group 1 there was significant radiological reduction loss. In conclusion, PLF with PSF was just as effective as ALIF with PSF in terms of clinical outcomes, but ALIF with PSF was superior to PLF with PSF in terms of the prevention of reduction loss. Anterior support would be helpful for preventing reduction loss in cases of spondylolytic spondylolisthesis of the lumbar spine.

High performance liquid chromatographic analysis of a new proton pump inhibitor KR60436 and its active metabolite O-demethyl-KR60436 in rat plasma samples using column-switching

A fully automated high performance liquid chromatography with column-switching was developed for the simultaneous determination of KR60436, a new reversible proton pump inhibitor, and its active metabolite O-demethyl-KR60436 from rat plasma samples. Plasma sample (50 microl) was directly introduced onto a Capcell Pak MF Ph-1 column (10 x 4 mm I.D.) where primary separation was occurred to remove proteins and concentrate target substances using acetonitrile-potassium phosphate (pH 7, 0.1 M) (2:8, v/v). The drug molecules eluted from MF Ph-1 column were focused in an intermediate column (10 x 2 mm I.D.) by the valve switching step. The substances enriched in intermediate column were eluted and separated on a Vydac 218MR53 column (250 x 3.2 mm I.D.) using acetonitrile-potassium phosphate (pH 7, 0.02 M) (47:53, v/v) at a flow rate of 0.5 ml/min when the valve status was switched back to A position. The method showed excellent sensitivity (detection limit of 2 ng/ml) with small volume of samples (50 microl), good precision and accuracy, and speed (total analysis time 24 min) without any loss in chromatographic efficiency. The response was linear (r2 > or = 0.999) over the concentration range of 5-500 ng/ml.

Epidermal growth factor receptor signaling mediates regranulation of rat nasal goblet cells

BACKGROUND

Mucus hypersecretion is a common response to inflammation in the lower airways and is a hallmark of chronic rhinitis.

OBJECTIVE

The purpose of this study was to elucidate the mechanisms of regranulation (mucus production) of goblet cells in nasal epithelium.

METHODS

Because neutrophils induce an epidermal growth factor (EGFR) cascade, we induced degranulation of goblet cells in rat nasal respiratory epithelium by means of intranasal inhalation of N-formyl-methionyl-leucyl-phenylalanine (fMLP), and we examined regranulation of the goblet cells and the role of EGFR inhibitors and neutrophils in the regranulation process.

RESULTS

In the control state Alcian blue/periodic acid-Schiff and mucin MUC5AC staining was present. Degranulation was induced in the nasal septal epithelium 4 hours after intranasal inhalation of fMLP (10(-7) mol/L); 48 hours later, goblet-cell regranulation was complete. In the control state EGFR protein staining was absent in the epithelium, but after fMLP-induced degranulation, EGFR protein was expressed. After pretreatment with BIBX1522, a selective EGFR tyrosine kinase inhibitor, fMLP-induced degranulation was unaffected, but goblet-cell regranulation was prevented completely.

CONCLUSION

These data suggest a role for the EGFR cascade in neutrophil-dependent production of goblet-cell mucins. Proving this theory will require the use of selective EGFR inhibitors in clinical studies of nasal hypersecretory states.

Electrophysiological characteristics of rat gustatory cyclic nucleotide--gated channel expressed in Xenopus oocytes

The complementary DNA encoding gustatory cyclic nucleotide--gated ion channel (or gustCNG channel) cloned from rat tongue epithelial tissue was expressed in Xenopus oocytes, and its electrophysiological characteristics were investigated using tight-seal patch-clamp recordings of single and macroscopic channel currents. Both cGMP and cAMP directly activated gustCNG channels but with markedly different affinities. No desensitization or inactivation of gustCNG channel currents was observed even in the prolonged application of the cyclic nucleotides. Single-channel conductance of gustCNG channel was estimated as 28 pS in 130 mM of symmetric Na(+). Single-channel current recordings revealed fast open-close transitions and longer lasting closure states. The distribution of both open and closed events could be well fitted with two exponential components and intracellular cGMP increased the open probability (P(o)) of gustCNG channels mainly by increasing the slower opening rate. Under bi-ionic conditions, the selectivity order of gustCNG channel among divalent cations was determined as Na(+) approximately K(+) > Rb(+) > Li(+) > Cs(+) with the permeability ratio of 1:0.95:0.74:0.63:0.49. Magnesium ion blocked Na(+) currents through gustCNG channels from both intracellular and extracellular sides in voltage-dependent manners. The inhibition constants (K(i)s) of intracellular Mg(2+) were determined as 360 +/- 40 microM at 70 mV and 8.2 +/- 1.5 mM at -70 mV with z delta value of 1.04, while K(i)s of extracellular Mg(2+) were as 1.1 +/- 0.3 mM at 70 mV and 20.0 +/- 0.1 microM at -70 mV with z delta of 0.94. Although 100 microM l-cis-diltiazem blocked significant portions of outward Na(+) currents through both bovine rod and rat olfactory CNG channels, the gustCNG channel currents were minimally affected by the same concentration of the drug.

Highly efficient Heck reactions of aryl bromides with n-butyl acrylate mediated by a palladium/phosphine-imidazolium salt system

[reaction: see text] A new phosphine-imidazolium salt, L.HBr (1, L = (1-ethylenediphenylphosphino-3-(mesityl))imidazol-2-ylidene), has been prepared. A combination of 0.5 mol % of Pd(dba)(2) and 0.5 mol % of L.HBr in the presence of 2 equiv of Cs(2)CO(3) as base has proven to be highly efficient in the Heck coupling reactions of aryl bromides (from electron-deficient to electron-rich aryl bromides) with n-butyl acrylate.

Randall-Sundrum model for self-tuning the cosmological constant

The vanishing cosmological constant in the four-dimensional space-time is obtained in a 5D Randall-Sundrum model with a brane (B1) located at y = 0. The matter fields can be located at the brane. For settling any vacuum energy generated at the brane to zero, we need a three-index antisymmetric tensor field A(MNP) with a specific form for the Lagrangian. For the self-tuning mechanism, the bulk cosmological constant should be negative.

A randomized double-masked crossover study comparing latanoprost 0.005% with unoprostone 0.12% in patients with primary open-angle glaucoma and ocular hypertension

PURPOSE

To compare the intraocular pressure)-lowering effect and side effects of latanoprost 0.005% once daily with unoprostone 0.12% twice daily.

METHODS

Sixty patients with primary open-angle glaucoma or ocular hypertension were randomized to receive either latanoprost once daily in the evening and placebo once daily in the morning, or unoprostone twice daily in the morning and evening. The study was double masked and followed a crossover design with two treatment periods of 1 month separated by a 3-week washout period. The intraocular pressure was measured at 9 AM and 5 PM on the baseline and day 28 visits, and at 9 AM on day 2 and day 14 visits of each treatment period. The 9 AM measurement was taken 2 hours and 13 hours after the last drop of unoprostone and latanoprost, and the 5 PM measurement was at 10 and 21 hours, respectively. The mean of the measurements was calculated. Safety parameters were also recorded.

RESULTS

Fifty-six patients completed both treatment periods and had intraocular pressure data available for evaluation. After 1 month of treatment, latanoprost significantly reduced intraocular pressure (mean +/- SEM) by 6.1 +/- 0.5 mm Hg (P <.001) and unoprostone by 4.2 +/- 0.4 mm Hg (P <.001) adjusted from an overall baseline of 22.3 +/- 0.5 mm Hg and 23.2 +/- 0.4 mm Hg, respectively. The difference of 1.9 mm Hg between treatments was statistically significant in favor of latanoprost [P =.003, analysis of covariance (ANCOVA)]. Unadjusted analysis of responders using the percentage decrease in intraocular pressure showed that the proportion of responders in the latanoprost-treated group was greater than in the unoprostone-treated group. Adverse ocular symptoms and findings were mild in both treatment groups. Eye redness and ocular irritation were the most frequently reported events.

CONCLUSIONS

Latanoprost once daily was significantly more effective in reducing intraocular pressure compared with unoprostone twice daily after 1 month of treatment in patients with primary open-angle glaucoma and ocular hypertension. Both drugs were well tolerated with few ocular adverse events.

Age-associated changes in gene expression patterns in the duodenum and colon of rats

In humans, decreased intestinal motility, compromised nutritional status and increased risk of colon cancer are commonly associated with aging. Here, we used the cDNA microarray analysis to detect age-associated changes in duodenal and colonic gene expression in male Fischer 344 rats. The primary finding of this study is that the magnitude and direction of age-associated changes in gene expression differs in the colon and duodenum. In the colon, 56 genes showed altered expression, whereas expression of only 25 genes was altered in the duodenum. The magnitude of change was greater in the colon than in the duodenum. The direction of change also differed; in the aged colon, expression of 51 genes increased and only five genes decreased. In contrast, in the aged duodenum, only seven genes increased, whereas 18 genes decreased in expression. In the duodenum of aged rats, expression of genes involved in ATP-generating pathways is decreased. In contrast, in the colon of aged rats, expression of genes involved in energy generating pathways and in lipid oxidation is increased. In addition, in the aging colon, an increased expression of genes that show an aberrant regulation in colon cancer, including CD44, ras, and maspin is observed. Collectively, these findings provide clues to molecular events that may be related to compromised intestinal function and the high incidence of colon cancer in the aged population.

Use of imaging for assessing anatomical relationships of tracheobronchial anomalies associated with left pulmonary artery sling

BACKGROUND

Proper recognition, classification and assessment of the tracheobronchial anatomy are essential for surgical management planning in left pulmonary artery sling (LPAS).

OBJECTIVE

To demonstrate the various imaging modalities in diagnosing and assessing anatomical relationships with tracheobronchial tree in LPAS.

MATERIALS AND METHODS

Seven patients (three infants, three children, one adult) with LPAS were evaluated. The confirmative imaging modalities included electron-beam tomography (EBT, n = 2), MRI (n = 1) and helical CT (n = 4). Other imaging modalities included plain chest radiographs (n = 7), barium oesophagogram (n = 2), echocardiography (n = 3), cardiac and pulmonary angiography (n = 2) and bronchoscopy (n = 5).

RESULTS

There were two cases of type IA, one case of type IIA and four cases of type IIB. All five cases of type II had a long segment of tracheobronchial stenosis. A long segment of thoracic tracheal stenosis was unusually associated in one case of type IA. All confirmative modalities were sufficient for diagnosing LPAS and assessing the tracheobronchial tree anomaly. However, helical CT could not obviate angiography due to associated congenital cardiac defects.

CONCLUSIONS

Sectional imaging modalities of EBT, MRI and helical CT were all sufficient for diagnosing and assessing the anatomical relationships of the tracheobronchial tree in LPAS.

Expression of human beta-defensin 1 mRNA in human palatine tonsil

Defensins are a newly delineated family of effector molecules whose contribution to host defense, inflammation and cytotoxicity may be considerable for humans. Beta-defensins are cationic peptides with broad-spectrum antimicrobial activity that are produced by epithelia at the mucosal surface. Tonsillar epithelium, which is constantly exposed to microorganisms, may express these natural antibiotic peptides as part of its protective function. In this study we searched for the expression of hBD-1 mRNA in palatine tonsillar epithelium without signs of infection, using reverse transcriptase-polymerase chain reaction and in situ hybridization. Total RNA was isolated from non-infected tonsil and hBD-1 mRNA was identified in these tissues. From in situ hybridization, the expression of hBD-1 mRNA was seen to be localized in the surface epithelia of palatine tonsil. These data suggest that hBD-1 of the palatine tonsil may also play an important role in innate defense against microorganisms.

Tinnitus caused by traumatic posterior auricular artery--internal jugular vein fistula

A patient with an arteriovenous fistula that developed after a traffic accident was recently treated. The patient noticed pulsatile tinnitus in the right orbital region two months after the accident. On the first visit, the preliminary clinical impression of this case was a carotid-cavernous fistula, but angiography showed a fistula between the posterior auricular artery and the internal jugular vein. Although rare, this arteriovenous fistula should be included in the differential diagnosis of pusatile tinnitus in the orbit region. The fistula was controlled by embolization with a platinum coil. This is the first report of an arteriovenous fistula between the posterior auricular artery and internal jugular vein.

Analysis of proteoglycan gene messages in human nasal mucosa and nasal polyp using dot blot hybridization

It has been suggested that the formation and growth of nasal polyp require the remodeling of extracellular matrix. Proteoglycans (PGs) are major components of the extracellular matrix that maintain the integrity of structural tissue. The leucine-rich repeat PGs include lumican, decorin and biglycan and have many important biologic activities in various pathologic conditions, including the remodeling of the extracellular matrix. Therefore, these small-PG families may be involved in the formation and growth of nasal polyp. In the present study, surgical specimens of nasal polyps and nasal mucosa were assessed for expression of mRNA coding for lumican, decorin and biglycan using reverse transcriptase-polymerase chain reaction followed by dot blot hybridization. Lumican, decorin and biglycan mRNA were expressed in all tissue samples examined. Semiquantitative dot blot hybridization revealed that the levels of the lumican and biglycan messages are lower in nasal polyp tissues than in nasal mucosa. The decorin messages in nasal polyp were expressed at levels similar to those in nasal mucosa. These results suggest that lumican, decorin and biglycan may be important components of the extracellular matrix in nasal mucosa. Considering the function of these PGs, normal levels of decorin associated with low levels of biglycan and lumican may play a role in the pathogenesis of nasal polyposis.

Recurrent lumbar disc herniation: results of operative management

STUDY DESIGN

A retrospective evaluation of 28 patients with recurrent lumbar disc herniation.

OBJECTIVES

To analyze the outcome of the revisions (repeat discectomy), the risk factors of recurrent disc herniation, and the factors that influenced the outcomes of repeat discectomy.

SUMMARY OF BACKGROUND DATA

Recurrent herniation following disc excision has been reported in 5-11% of patients. There have been many studies on recurrent disc herniation, but these studies have analyzed mixed patient populations.

METHODS

Recurrent lumbar disc herniation was defined as disc herniation at the same level, regardless of ipsilateral or contralateral herniation, with a pain-free interval greater than 6 months. Eight women and 20 men were studied. The levels of disc herniation were L4-L5 (19 cases) and L5-S1 (9 cases). Gadolinium-enhanced magnetic resonance imaging was performed in all patients. Revision surgery was performed in all patients by using conventional open discectomy. The pain-free interval, side and degree of herniation, operation time, duration of hospital stay, and clinical improvement rate were recorded.

RESULTS

The mean pain-free interval was 60.8 months. There were 21 cases of ipsilateral herniation and 7 cases of contralateral herniation. The degrees of herniation in revision were protrusion (14 cases), subligamentous extrusion (3 cases), transligamentous extrusion (8 cases), and sequestration (3 cases). The degrees of herniation in the previous discectomy were protrusion (17 cases), subligamentous extrusion (10 cases), and transligamentous extrusion (1 case). The length of surgery was significantly different (P = 0.003) between the revision surgery and the previous discectomy. There were no significant differences between revision and previous surgery in terms of hospital stay or clinical improvement rates. Age, gender, smoking, professions, traumatic events, level and degree of herniation, and pain-free interval did not affect the clinical outcomes.

CONCLUSION

Conventional open discectomy as a revision surgery for recurrent lumbar disc herniation showed satisfactory results that were comparable with those of primary discectomy. Based on the results of this study, repeat discectomy can be recommended for the management of recurrent lumbar disc herniation.

Lumbosacral scoliotic list by lumbar disc herniation

STUDY DESIGN

A prospective study of 45 patients with lumbar disc herniation and scoliotic list who had undergone conventional open discectomy.

OBJECTIVES

To determine the association between the location of the disc herniation and the direction of sciatic scoliotic list and to clarify the mechanism of sciatic scoliosis.

SUMMARY OF BACKGROUND DATA

The association between the scoliotic list and lumbar disc herniation is well known. However, there have been few studies regarding the direction of scoliotic list and the location of the disc herniation observed during surgery.

METHODS

The direction of scoliotic list, the preoperative and postoperative Cobb's angle, and the displacement of the first lumbar vertebra from the center sacral line were measured. The location, side, and degree of disc herniation were observed during surgery.

RESULTS

There was no statistically significant association observed between the location or degree of nerve root compression and the direction or degree of sciatic scoliosis. Moreover, there was no statistically significant association observed between the location or degree of nerve root compression and the displacement of the first lumbar spine from the center sacral line. However, there was a significant association between the side of the disc herniation and the direction of sciatic scoliosis. Most of the sciatic scoliotic list disappeared after surgical decompression.

CONCLUSION

The direction of sciatic scoliosis was not observed to be associated with the location of nerve root compression, although it was related to the side of disc herniation.

Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions

Wang Y, Winchester PA, Khilnani NM, et al. Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170-177.

RATIONALE AND OBJECTIVES

To obtain reliable contrast-enhanced peripheral MR angiography for imaging peripheral vascular disease from the abdominal aorta to the pedal arteries.

METHODS

A protocol consisting of contrast-enhanced, dynamic two-dimensional (2D) acquisition at the feet and calf and bolus-chase three-dimensional (3D) acquisition from the abdominal aorta to the calf was developed and applied in patients with peripheral vascular disease. The performance of this integrated protocol was assessed in 89 consecutive patients.

RESULTS

The bolus-chase 3D acquisition was of diagnostic quality in 100% of the acquisitions in the abdomen, 96% in the thigh, and 43% in the calf. The poor quality of the calf acquisitions was due to insufficient spatial resolution, poor arterial signal, and venous contamination. Diagnostic-quality images were obtained in 100% of the dynamic 2D acquisitions of the calf and 98% of the feet.

CONCLUSIONS

The combined dynamic 2D and bolus-chase 3D contrast-enhanced MR angiography technique provides diagnostic images of the entire lower extremity.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

CMT-3, a non-antimicrobial tetracycline (TC), inhibits MT1-MMP activity: relevance to cancer

Tetracyclines (TCs) and their non-antimicrobial analogs (CMTs) have therapeutic potential to inhibit tissue destructive disease processes, such as cancer invasion and metastasis, by inhibiting certain matrix metalloproteinases. Enhanced matrix metalloproteinase-2 (MMP-2; gelatinase A) activity has been correlated to cancer invasiveness, and membrane type MMP (MT1-MMP) expressed by tumor cells is involved in localizing and activating pro-MMP-2, a pathway believed to mediate cancer induced tissue breakdown. CMT-3 (6-demethyl, 6-deoxy, 4-dedimethylamino TC) has been shown to experimentally suppress prostate cancer, colon adenocarcinoma and melanoma invasiveness in cell culture and to inhibit tumor growth and metastasis in vivo and was used in the current in vitro study. Confluent MT1-MMP transfected COS-1 cells were harvested, washed thoroughly, subjected to N(2) cavitation and cell membrane enriched fractions were isolated by sequential centrifugations. This MT1-MMP preparation exhibited (i) pro-MMP-2 activating activity as shown by molecular weight shift of this gelatinase from 72 kDa to 62 kDa using gelatin zymography, and (ii) the ability to degrade both [(3)H-methyl] gelatin and casein at 37 degrees C. Adding CMT-3 at final concentrations of 5--20microM inhibited MT1-MMP gelatinolytic and caseinolytic activity, blocked MT1-MMP activation of pro-MMP-2, and decreased invasiveness (using the Matrigel system) of HT-1080 fibrosarcoma cells. The inhibition of MT1-MMP by CMT-3 may partially explain the inhibition of cancer cell -mediated tissue breakdown and invasiveness by this non-antimicrobial tetracycline analog.

Inhibition of tumor cell invasiveness by chemically modified tetracyclines

COLO 205 is a cell line derived from a human colon carcinoma with high degradative activity towards extracellular matrix (ECM). It has been shown that COLO 205 cells produce matrix metalloproteinases (MMPs). MMPs are a family of enzymes known to degrade components of the ECM and have been implicated in tumor invasion. In the present study, we have analyzed the multiple effects of chemically modified tetracyclines (CMTs) on the expression and activity of MMPs secreted by COLO 205 cells in vitro with the aim of evaluating these compounds for potential use in management of invasive tumors. Because COLO 205 cells can degrade an interstitial ECM in serum-free medium in vitro, we have been able to compare the effects of the tetracyclines on this measure of invasive activity with their effects on proteinase expression and activity. We demonstrate here that one of the chemically modified tetracyclines, 6-deoxy-6-demethyl-4-de(dimethylamino)tetracycline (CMT-3) can effectively inhibit ECM degradation mediated by COLO 205 cells or their conditioned medium. Gelatin zymography and immunoblots show that CMT-3 has the ability to inhibit release of MMP-2 into conditioned medium as well as to inhibit MMP-2 gelatinolytic activity, which correlates with the results from ECM degradation assays. On the basis of our findings with COLO 205 cells we have expanded our evaluation of the tetracyclines to include effects on a genetically engineered line of MDA-MB-231 breast tumor cells overexpressing MMP-9 at levels over tenfold those of the parent cell line, and on three human prostate tumor cell lines, LNCaP, DU-145, and PC-3. We show here that CMT-3 displays multiple modes of action: inhibiting MMP activity, reducing levels of MMP expression, and exhibiting selective cytotoxicity towards some of the tumor cell lines.

The lipophilicity, pharmacokinetics, and cellular uptake of different chemically-modified tetracyclines (CMTs)

CMTs are analogs of tetracyclines, which are chemically modified to eliminate their antimicrobial efficacy but which retain their inhibitory activity against matrix metalloproteinases. These compounds have been found to inhibit connective tissue breakdown in animal models of diseases such as periodontitis, arthritis and cancer. Because CMTs exhibit different in vivo efficacy in these various models of disease, the current study compared their pharmacokinetics and other properties as follows: Adult male Sprague-Dawley rats were administered by oral gavage a single dose of 5mg of different CMTs suspended in 1 ml 2% carboxymethyl-cellulose, and blood samples were collected from 1-48 hours after dosing. The sera were extracted, then analyzed by HPLC using a C-18 reverse-phase column. The results showed that the peak concentrations (C(max)) in rat sera 1-12 hours after oral administration of CMTs -1, -2,-3, -4,-5,-6,-7,-8 and doxycycline were 5.5, 0.7, 4.6, 6.2, 0.8, 0.7, 9.0 (note: the 3 peaks detected for CMT-7 were combined), 15.0 and 0.9 microg/ml, respectively. Their in vivo half-lives (t(1/2)) were 11, 5, 22, 11, 32, 15, 37, 38, and 17 hours, respectively. Of the anticollagenase CMTs tested, CMT-8 showed the greatest C(max) and t(1/2)values, followed by CMTs-3, -1, -4, and perhaps -7; CMTs-2, -5, and -6 exhibited much lower levels in serum. The relative lipophilicities of the 8 CMTs and doxycycline were tested by examining their extractability in octanol. The results showed that CMT-2, -5, and -6 had the lowest partition coefficients using this organic solvent, while CMT-3 was the most lipophilic. The lipophilicity of the different CMTs was also positively correlated (r(2)=0.767, P<0.05) to peak serum concentrations (C(max)), but not to their serum half-lives (r(2)=0.25,P=0.49). This property of the different CMTs was also found to be positively correlated to their ability to enter into human whole blood cells in vitro (r2=0.95, P<0.001). Since CMT-8, as well as CMTs-3 and -1, consistently exhibited the greatest in vivo efficacy in animal models of tissue breakdown, this may reflect, at least in part, their favorable pharmacokinetics and tissue uptake.

Detection of hepatitis C virus in the corneas of seropositive donors

PURPOSE

There have been no reported cases of hepatitis C virus (HCV) transmission by corneal transplantation. Previous studies have also shown no correlation between HCV seropositivity and the presence of HCV RNA in the corneal tissues. This study aims to investigate such correlation and to provide further evidence to the possible transmissibility of HCV via corneal grafts.

METHODS

Of the 1,619 potential corneal donors to the Eye Bank of Canada over a 1-year period, 15 tested HCV-positive by the second-generation Abbott HCV enzyme immunoassay (EIA) 2.0 assay. Their sera were further tested with second-generation radio-immunoblot assay (RIBA-II), and their corneas (29 altogether) were processed for identification of HCV RNA using polymerase chain reaction (PCR).

RESULTS

Of the 29 corneas from seropositive donors, HCV RNA was detected in 7 (24.1%).

CONCLUSION

This is the first study in the literature that demonstrates a significant correlation between HCV seropositivity and the presence of HCV in the corneas. Routine HCV serologic testing for all potential corneal donors and rejection of corneal tissues based on HCV seropositivity is certainly justifiable.

Involvement of the XpsN protein in formation of the XpsL-xpsM complex in Xanthomonas campestris pv. campestris type II secretion apparatus

The xps gene cluster is required for the second step of type II protein secretion in Xanthomonas campestris pv. campestris. Deletion of the entire gene cluster caused accumulation of secreted proteins in the periplasm. By analyzing protein abundance in the chromosomal mutant strains, we observed mutual dependence for normal steady-state levels between the XpsL and the XpsM proteins. The XpsL protein was undetectable in total lysate prepared from the xpsM mutant strain, and vice versa. Introduction of the wild-type xpsM gene carried on a plasmid into the xpsM mutant strain was sufficient for reappearance of the XpsL protein, and vice versa. Moreover, both XpsL and XpsM proteins were undetectable in the xpsN mutant strain. They were recovered either by reintroducing the wild-type xpsN gene or by introducing extra copies of wild-type xpsL or xpsM individually. Overproduction of wild-type XpsL and -M proteins simultaneously, but not separately, in the wild-type strain of X. campestris pv. campestris caused inhibition of secretion. Complementation of an xpsL or xpsM mutant strain with a plasmid-borne wild-type gene was inhibited by coexpression of XpsL and XpsM. The presence of the xpsN gene on the plasmid along with the xpsL and the xpsM genes caused more severe inhibition in both cases. Furthermore, complementation of the xpsN mutant strain was also inhibited. In both the wild-type strain and a strain with the xps gene cluster deleted (XC17433), carrying pCPP-LMN, which encodes all three proteins, each protein coprecipitated with the other two upon immunoprecipitation. Expression of pairwise combinations of the three proteins in XC17433 revealed that the XpsL-XpsM and XpsM-XpsN pairs still coprecipitated, whereas the XpsL-XpsN pair no longer coprecipitated.