Low-dose doxycycline inhibits bone resorption associated with apical periodontitis.

AIM: To test the effect of low-dose doxycycline on bone resorption associated with apical periodontitis. METHODOLOGY: Apical periodontitis was induced by occlusal pulp exposure in the mandibular first molars of 36 rats. Animals were divided into three groups of 12: group A received doxycycline in drinking water at a dose of 5.85 mg day(-1); group B received a dose of 1.48 mg day(-1) (one-quarter of the original dose); and group C received no medicament and served as the control. A bioassay determined the doxycycline serum levels. After 21 days, the mandibles were removed, radiographed and the radiographs scanned to generate digital images. These images were analysed morphometrically and the total area of the periapical bone resorption of the mesial and distal roots of each tooth was determined and used to compare the groups. Statistical analysis was completed using anova with repeated measures. RESULTS: The mean doxycycline serum level in group A was 0.22(+/-0.03) microg mL(-1) and in group B below the detection level of the assay (<0.062 microg mL(-1)). The mean area of the periapical bone resorption in the control group C was 2.91(+/-0.61) mm(2). In animals treated with a low-dose doxycycline, the mean size of the bone resorption was significantly smaller at 1.59(+/-0.59) mm(2) (group A) and 1.72(+/-0.85) mm(2) (group B) (P = 0.001). No significant difference was found in the area of the bone resorption between these two groups A and B. CONCLUSIONS: Low-dose doxycycline reduced the area of bone resorption associated with apical periodontitis in the mandibular first molar teeth of rats.

Possible role of fibrinogen in the aggregation of white blood cells.

In order to verify whether leukocyte aggregation correlated with aggregation of other cellular elements during inflammation, we examined the state of leukocyte adhesiveness/aggregation (LAA) in the peripheral blood and red cell aggregation. Correlation was found to be significant as was the correlation between LAA and fibrinogen, and with the fibrin/fibrinogen degradation products concentration during various inflammatory states. In vitro leukocyte aggregation was decreased when the cells were suspended in autologous heat defibrinogenated plasma as compared to cells suspended in autologous native plasma. Heat aggregated fibrinogen but not native fibrinogen caused leukocyte aggregation in vitro. Finally, Arvin defibrinogenation in rabbits reduced the state of LAA in endotoxinemic rabbits. Integrating all this information, we assume that fibrinogen participates not only in the aggregation phenomena of red cells and platelets, but also in those of leukocytes.

Comparative effects of indomethacin on cell proliferation and cell cycle progression in tumor cells grown in vitro and in vivo.

Considerable research effort is currently being directed towards understanding the mechanisms mediating the antiproliferative effects of non-steroidal anti-inflammatory drugs (NSAIDs) and, more recently, of cyclooxygenase (COX)-2 inhibitors as well. A key question is whether NSAIDs (excluding sulindac) exert their anticarcinogenic effects in vivo by a mechanism that is dependent on their capacity to inhibit COX activity. Some studies with cultured tumor cells in vitro have argued against such a linkage, showing that NSAIDs inhibit cell replication and/or augment apoptosis only at concentrations that exceed those required to inhibit COX activities 10- to 100-fold. The significance of these results for the observed anticarcinogenic effects of NSAIDs in vivo has not yet been evaluated. We addressed this question by comparing, for the same tumor cells, the effects of the NSAID indomethacin on cell growth parameters when the cells were grown in culture to the effects seen in the in vivo growing tumor in the mouse. Indomethacin added to cultured Lewis lung carcinoma cells exerted a potent antiproliferative effect ((3)H thymidine assay) and reduced cell viability (MTT[3-(4,5-dimethyl(thiazol-2-yl)-2,5 diphenyl tetrazolium bromide] assay) at low doses (10-20 microM) in parallel with its inhibitory effect on cellular cyclooxygenase. These effects of indomethacin appeared to arise from a clear antiproliferative shift in the profile of the cell cycle parameters towards a reduced percentage of cells at the S and G(2)/M phases, together with an increased percentage of cells at the G(1) phase. Significantly, similar results were seen when indomethacin was given in vivo at the low dose of 2 mg per kg/day, which blocked blood platelet COX activity and at the same time produced a delay in tumor growth initiation and attenuation of apparent primary tumor growth as well as growth of lung metastases. These results thus provide strong support for the notion that COX inhibition is a major determinant in the antitumorigenic effect of indomethacin in vivo.

NADH-dependent prostaglandin E2-9-ketoreductase activity and prostaglandin synthesis in the Brattleboro rat kidney: effects of the antidiuretic hormone.

The activity of prostaglandin (PG)E2-9-ketoreductase (9KR), an enzyme catalyzing the conversion of PGE2 to PGF2 alpha, was significantly increased in glomerular and cortical homogenates of diabetes insipidus (DI) rats, as compared to normal Long Evans (LE) rats, and did not change with ADH treatment. Medullary 9KR was similar in the three groups and papillary 9KR was increased, but not significantly, in both groups of DI rats. Km values for PGE2 and NADH were compared in the various compartments of the kidney. Levels of 9KR were not correlated with the PGE/PGF ratio in urine or supernatants. The synthesis of PGE2 and PGF2 alpha by isolated glomeruli was increased in DI rats. This was not reversed by ADH treatment, PGE2 synthesis increasing even further, especially in the presence of arachidonic acid. In contrast, medullary slices produced significantly less PGs in DI than in LE rats and returned to normal with ADH treatment. Papillary slices produced similar quantities of prostaglandins in all groups. The results do not support the concept that the alterations in PG synthesis observed in DI rat are related only to changes in 9KR activity, but do not exclude the possibility that the enzyme participates in the regulation of PG biosynthesis.

Enhanced electroretinogram in cats induced by exposure to mercury acetate.

The present study was undertaken in order to verify whether, and how, retinal functions are affected by subacute poisoning with organic mercury. Mercury acetate in various concentrations (0.025-0.25 mg/kg per day) was injected subcutaneously every second day to adult cats (N = 20) throughout a 2.5-4.0-week period. The electroretinogram (ERG) was recorded and the Hg2+ concentrations in the blood were determined. In nearly 90% of the intoxicated cats an enhanced electroretinogram (scotopic b-wave amplitude) was found as compared to its level in the normal control cats (N = 10). The latency of the ERG was found to be appropriately shorter, up to a maximal difference of nearly 20% in comparison to the controls. Hg2+ was present in the blood of the exposed cats during a 2.5-month period following the exposure. It is concluded that exposure to mercury acetate induces a permanent increase in the excitability level of the cat's retina.

Leukergy--a new diagnostic test for bone infection.

This new blood test for infection is based on the phenomenon of leukergy in which white cells agglomerate in the peripheral blood of patients with inflammatory diseases. It was used in 26 patients with proven bone or joint infection and was positive in 25. The leukergy test was more accurate than the ESR, white cell count or blood culture. The percentage of cells agglomerated correlated with the clinical severity of the infection and the test detected reactivation of the septic process better than the other haematological tests. It is a rapid and inexpensive method which is useful in the diagnosis and management of bone and joint infections.

Carbon dioxide laser and silver halide infrared transmitting fibers for tympanoplasty: an experimental animal model.

OBJECTIVE: This study evaluates the effectiveness and safety of fiberoptic carbon dioxide (CO2) laser welding for graft closure of tympanic membrane perforations in an animal model. STUDY DESIGN AND SETTING: Tympanic membrane perforation was surgically induced in 11 eardrums of 7 given pigs. A lumbar facial graft was placed over the wound, and albumin drops served as a biologic solder. CO2 laser energy, transmitted through silver halide infrared transmitting fibers, was used for "spot-welding" along the circumference of the graft. The welded sites were evaluated by using a surgical microscope as well as by evaluating the sites histologically. RESULTS: Healing started 3 to 4 days after surgery and was completed within 3 weeks with the formation of a neotympanum. Some inflammation with granulation tissue was noted in 5 eardrums. CONCLUSIONS AND SIGNIFICANCE: These preliminary results indicate that CO2 laser tympanoplasty with a fiberoptic delivery system may be a promising new technique for the clinical setting.

A preclinical study of EO-122, a new lidocaine-like antiarrhythmic drug.

The 2,6-dimethylanilide of quinuclidine-3-carboxylic acid hydrochloride (EO-122), a new structural analog of lidocaine, has been shown to possess potent antiarrhythmic activity in experimentally induced arrhythmias in animals. Restoration of normal sinus rhythm and suppression of ouabain-induced arrhythmia in cats and dogs, and of coronary occlusion-induced arrhythmia in dogs, followed a single IV injection of 1--3 mg/kg, with an onset of 2 minutes and a duration of 20--240 minutes. Occlusion-induced arrhythmia was likewise suppressed after an oral dose of 10--20 mg/kg, with an onset of 11--65 minutes and a duration of 25--120 minutes. Under similar conditions, lidocaine was either totally ineffective or of ultra-short duration. The bioavailability of EO0122 by the oral route exceeded 80% of the oral dose. Therapeutic blood concentrations were in the range 0.5--7 microgram/ml. At about 5 microgram/ml there was a slight depression of cardiac function in the anesthetized cat, but not in the conscious dog. In cats, complete A-V block occurred at concentrations of 60--70 microgram/ml. The IV LD50 in mice was 22 mg/kg, and in rabbits 8.5 mg/kg. No overt signs of neurotoxicity could be observed at any dose of EO-122. The pharmacokinetic profile of the drug fits a two-compartment open model, with t1/2 congruent to 150 min and Vd (SS) congruent to 1.5 l/kg.

Castration prevents calcium channel blocker-induced gingival hyperplasia in beagle dogs.

1. The purpose of this study was to investigate testosterone's role on the calcium channel antagonist oxodipine-inducing gingival hyperplasia in a dog model. 2. Two experiments were conducted using castrated and intact male dogs. Oxodipine was administered orally for 90 days, at a dose of 24 mg/kg/day. In the first experiment, the occurrence of gingival hyperplasia was evaluated. In the second, the gingival index (GI) and gingival hyperplasia index (GHI) were recorded and correlated with serum levels of testosterone. 3. A significant positive correlation between GI, GHI and plasma testosterone was noted. Castrated dogs were injected with testosterone, 4 months after the start of oxodipine treatment, while in the non-castrated dogs, administration of oxodipine was stopped. Castration correlated with lack of GH, while testosterone injection to the same dogs was associated with an increase of GI and GHI. 4. Since it is known that testosterone receptors are present in the gingiva, it is proposed that oxodipine-induced gingival hyperplasia could be mediated by the calcium channel blocker on plasma testosterone levels.

Successful intraperitoneal nutrition in rabbits with short-bowel syndrome.

The efficacy of intraperitoneal alimentation as a means of nutritional support for various degrees of short-bowel syndrome was studied, using the rabbit model. Twenty-eight rabbits were divided into 5 groups. Group I had a sham operation; Groups II, III and IV had 50 %, 75 % and 90 % small-bowel resections (SBR), respectively; Group V had a 90 % SBR with intraperitoneal nutrition. All the rabbits received a regular diet and tap water post-operatively. The rabbits in Group V received intraperitoneal alimentation (IPA) by way of a peritoneal catheter inserted at the time of surgery. The nutrition consisted of 10 % dextrose with 5.5 % amino acids. This provided 30 - 35 kcal/kg of additional energy per day. All the rabbits within Group IV (90 % resection without IP nutrition) died within 2 to 5 weeks. IP nutrition enabled body weight to be maintained and prevented the death of all rabbits with 90 % small-bowel resection.

Generation of auto-antibodies towards Alzheimer's disease vaccination.

We developed a novel procedure to evoke anti-aggregating beta-amyloid (Abeta) antibodies, using filamentous phages displaying only four amino acids EFRH of the beta-amyloid peptide (AbetaP). This epitope was found to be the main regulatory site for fibril formation. For the first time, effective auto-antibodies have been obtained in guinea-pigs, which exhibit human identity in the AbetaP. Immunization through a phage-carrying epitope was found to be long-lasting, and no toxic effect caused by autoimmune response was detected in the challenged animal sections. These antibodies performed similarly to site-directed monoclonal antibodies and to antibodies raised against fibrillar Abeta in disaggregation of plaques, and may serve as the basis for developing an anti-Abeta vaccine.

Leukocyte agglomeration test to reveal bacterial infections in mice.

A simple and rapid procedure was used to detecting covert bacterial infections in mice. The procedure was based on observations that bacterial infections were associated with clumping of leukocytes. A large drop of citrated venous blood was placed on a slide and allowed to spread. After fixation and staining the percentage of agglomerated leukocytes was determined by counting. Experimental urinary tract infections caused by either Escherichia coli or Proteus mirabilis served as a model to test the efficacy of the method. Elevation of leukocyte agglomeration was observed in these localized infections.

The effect of poly I:C and IUDR on the inhibition of HSV in rabbit eyes.

The inhibition of herpetic keratitis by a combination of Poly I:C with DEAE-Dextran and IUDR was studied in rabbit eyes. This treatment was administered 72 h after HSV inoculation (daily) for 3 days and continued once daily for another 2-3 days. A significant improvement was detected in rabbit eyes beginning on the first day of treatment, and there was minimal scarring. This improvement in herpetic keratitis coincided with a decrease in the virus titer isolated from rabbit eyes and an increase in interferon titer detected in rabbit tears. The cornea and trigeminal ganglia of treated and control rabbits were tested in order to prove whether this combined treatment could inhibit the migration of HSV from the cornea to the trigeminal ganglia. During the active stage of the disease, HSV was isolated in a lower titer from the cornea of the treated rabbits and from the ganglia of only half of this rabbit group. During the latent stage of the disease, no HSV was isolated from the cornea of either rabbit group, but HSV was isolated from the ganglia explants of the treated rabbits in a somewhat lower titer than from the controls. This treatment administered 3 days after the virus inoculation could not prevent the migration of HSV from the infected cornea towards the trigeminal ganglia.

Clearance of Serratia marcescens from blood in mice: role of hydrophobic versus mannose-sensitive interactions.

In the present study, we examined the potential roles of cell surface hydrophobicity and mannose-sensitive (MS) interactions in blood clearance of Serratia marcescens in mice. Hydrophobic strain RZ, partially hydrophobic mutant 3162, and nonhydrophobic mutant 3164 were coinoculated into BALB/c male mice, and blood samples were plated out at different time intervals; colonies of the three strains were distinguished by their different morphologies. All three strains were cleared from the blood stream at similar rates, despite their large relative differences in cell surface hydrophobicity. Clearance from blood was subsequently studied by coinoculating two clinical isolates which differ in their abilities to adhere via MS interactions. MS+ strain 1785 was cleared much more rapidly than MS- strain 3255; moreover, in the presence of D-mannose, clearance of strain 1785 was inhibited to a rate similar to that of MS- strain 3255. When D-glucose was substituted for D-mannose, inhibition was not observed. The results suggest that MS, rather than hydrophobic, interactions are primarily responsible for the rapid clearance of S. marcescens from blood observed.

Effect of sodium loading on the urinary excretion of prostaglandins E2 and F2 alpha in rats with hereditary diabetes insipidus (Brattleboro rats).

Current evidence suggests that the antidiuretic hormone (ADH) and changes in sodium balance influence renal prostaglandins (PGs). To separate these two mechanisms, the effect of sodium loading on the urinary excretion of PGE2 and PGF2 alpha was studied in female Brattleboro rats with diabetes insipidus (DIHO) and compared with that in female, age matched, heterozygous Long Evans controls (LEHE). Ten DIHO and ten LEHE rats had a normal sodium intake. In ten DIHO rats a 0.16% NaCl solution was supplied instead of drinking water for either 8 days (n = 5) or 14 days (n = 5). In two groups of LEHE rats, sodium loading was obtained with a 0.80% NaCl solution for the same study periods. Urine PGs were measured by radioimmunoassay in three 24 h urine collections for each rat. Urine PGs were significantly increased in the 8 day loaded but not in the 14 day loaded LEHE rats. In DIHO rats, a non-significant increase in both PGE2 and PGF2 alpha was present after 8 days of sodium loading, while PGE2 and the E/F ratio were decreased after 14 days of salt loading. The findings suggest that the natriuresis induced by sodium loading in the rat may be mediated in part by increased production of PGs. In addition, it seems that ADH plays a role in this response.

Sodium intake as a determinant of urinary prostaglandin excretion. Studies in the Brattleboro rat.

In order to investigate the effects of changes in sodium (Na) balance on the renal production of prostaglandins (PG) E2 and F2 alpha in the absence of antidiuretic hormone (ADH), studies were performed in Brattleboro rats, without endogenous ADH, and in heterozygote Long Evans rats which served as controls. All rats received a diet virtually devoid of Na, with distilled water ad libitum, and Na intake was modified by adding different quantities of Na to the drinking water. Three groups were studied for each strain: normal Na intake, low Na intake and Na loading. At the end of a 14 day diet period, urinary PGE2 and PGF2 alpha were measured by radioimmunoassay in collections obtained for three consecutive days. In the Na depleted animals, both PGE2 and PGF2 alpha decreased. The PGE2/PGF2 alpha ratio (E/F ratio) was unchanged. In contrast, Na loading induced a significant decrease of PGE2 but PGF2 alpha increased, though not significantly. The E/F ratio was significantly decreased. The results were qualitatively similar in the presence or absence of ADH, but the Brattleboro rats, overall, excreted less PGs than controls. The results suggest that changes in Na balance are major factors influencing urinary PG excretion. These substances probably play a role in the modifications of Na handling by the kidney in different balance states.

Indomethacin inhibits the accumulation of tumor cells in mouse lungs and subsequent growth of lung metastases.

BACKGROUND: The interaction of cancer cells with blood cells and cell wall components evokes inflammatory responses and is a critical event in the metastatic process. Indomethacin is a potent inhibitor of the cyclooxygenase (COX) enzymes and has previously been shown to decrease the growth of primary tumors in vivo. Proinflammatory prostaglandins produced by the two COX enzymes may also play a role in the development of metastases. METHODS: To directly address this question, we tested the effect of indomethacin on the accumulation of circulating [(3)H]-uridine-labeled tumor cells in the lungs and on the subsequent development of lung tumors. RESULTS: We found that inhibition of COX activity in the recipient mice prior to the injection of tumor cells decreased the percentage of the cells arrested in the lungs. This effect was highly significant since it subsequently led to substantial attenuation of lung metastasis development. CONCLUSION: These data thus demonstrate the antimetastatic effect of indomethacin through a mechanism which involves a reduction in tumor cell uptake by the lungs.

Temperature controlled CO(2) laser welding of soft tissues: urinary bladder welding in different animal models (rats, rabbits, and cats).

BACKGROUND AND OBJECTIVE: Laser welding of tissues is a method of closure of surgical incisions that, in principle, may have advantages over conventional closure methods. It is a noncontact technique that introduces no foreign body, the closure is continuous and watertight, and the procedure is faster and requires less skill to master. However, in practice, there have been difficulties in obtaining strong and reliable welding. We assumed that the quality of the weld depends on the ability to monitor and control the surface temperature of the welded zone during the procedure. Our objective was to develop a "smart" fiberoptic laser system for controlled temperature welding. STUDY DESIGN/MATERIALS AND METHODS: We have developed a welding system based on a CO(2) laser and on infrared transmitting AgClBr fibers. This fiberoptic system plays a double role: transmitting laser power for tissue heating and noncontact (radiometric) temperature monitoring and control. The "true" temperature of the heated tissue was determined by using an improved calibration method. We carried out long-studies of CO(2) laser welding of urinary bladders in various animal models. Cystotomies were performed on the animals, and complete closure of the bladder was obtained with a surface temperature of 55 +/- 5 degrees C at the welding site. RESULTS: In early experiments on 31 rats, the success rate was 73%. In later experiments with 10 rabbits and 3 cats, there was an 80% and a 100% success rate, respectively. CONCLUSION: The success rate in these preliminary experiments and the quality of the weld, as determined histologically, demonstrate that temperature controlled CO(2) laser welding can produce effective welding of tissues. The fiberoptic system can be adapted for endoscopic laser welding.