Excellent performance of aromatic polyguanamines induced by multiple hydrogen bondable tetraazacalix[2]arene[2]-triazine ring in their main chain.

A series of poly(guanamine) (c-PG)s containing tetraazacalix[2]arene[2]-triazine (mPDA2CyC2) were successfully prepared by solution polycondensation of mPDA2CyC2 with various aromatic diamines in an aprotic organic solvent with a lithium chloride additive (5 wt%) at 150 °C for 6 hours. The number-average molecular weights (M n)s of these c-PG polymers reached up to 31 500, with a relatively broad molecular weight distribution (M w/M n) of 5.3. They showed good solubility in aprotic organic solvents, such as N-methylpyrrolidone and N,N-dimethylacetamide at a concentration of 2 mg mL-1. The glass transition temperatures (T g) of the c-PG polymers were in the range 359 °C-392 °C, approximately 160 °C higher than those of counterpart polymers (i.e., with no aza-calixarene-based PG (l-PG)). The coefficients of thermal expansion (CTEs) of the c-PG polymers were 29.7-48.1 ppm K-1 (at 100 °C-150 °C), much lower than those of l-PG samples, i.e., 59.1-85.1 ppm K-1. Transparent and almost colorless c-PG films were successfully prepared by a solution casting method, showing maximum tensile strength (σ S), modulus (E γ), and elongation at break (E b) values of 151 MPa, 6.3 GPa, and 4.4%, respectively, for the c-PG polymer from mPDA2CyC2 and 4,4'-oxydianiline monomers. The corresponding l-PG film exhibited σ S, E γ, and E b values of just 76 MPa, 5.4 GPa, and 1.6%, respectively. These outstanding thermal and mechanical properties of the c-PG polymers can be attributed to their multiple hydrogen bonding interaction between mPDA2CyC2 residues in the polymer backbone. This interaction was identified by infrared spectroscopy measurements at the broad absorption band around 3000-3400 cm-1.

Selective intracellular vaporisation of antibody-conjugated phase-change nano-droplets in vitro.

While chemotherapy is a major mode of cancer therapeutics, its efficacy is limited by systemic toxicities and drug resistance. Recent advances in nanomedicine provide the opportunity to reduce systemic toxicities. However, drug resistance remains a major challenge in cancer treatment research. Here we developed a nanomedicine composed of a phase-change nano-droplet (PCND) and an anti-cancer antibody (9E5), proposing the concept of ultrasound cancer therapy with intracellular vaporisation. PCND is a liquid perfluorocarbon nanoparticle with a liquid-gas phase that is transformable upon exposure to ultrasound. 9E5 is a monoclonal antibody targeting epiregulin (EREG). We found that 9E5-conjugated PCNDs are selectively internalised into targeted cancer cells and kill the cells dynamically by ultrasound-induced intracellular vaporisation. In vitro experiments show that 9E5-conjugated PCND targets 97.8% of high-EREG-expressing cancer cells and kills 57% of those targeted upon exposure to ultrasound. Furthermore, direct observation of the intracellular vaporisation process revealed the significant morphological alterations of cells and the release of intracellular contents.

Fatal tracheal aspergillosis during rituximab combined chemotherapy for diffuse large B-cell lymphoma that developed after lung transplantation.

Invasive tracheal aspergillosis (ITA) is an infection that is unique to patients who have undergone lung transplantation (LT). Although the activity of this disease often appears on imaging, we encountered a case of ITA that became exacerbated, despite few computed tomography (CT) findings, during rituximab combined chemotherapy for diffuse large B-cell lymphoma. ITA developed during immunosuppressive therapy after LT. Because CT findings may show false-negative results, bronchoscopy is recommended for such cases.

Atomoxetine reverses locomotor hyperactivity, impaired novel object recognition, and prepulse inhibition impairment in mice lacking pituitary adenylate cyclase-activating polypeptide.

Attention-deficit/hyperactivity disorder (ADHD) is a complex neurobehavioral disorder that is characterized by attention difficulties, impulsivity, and hyperactivity. A non-stimulant drug, atomoxetine (ATX), which is a selective noradrenaline reuptake inhibitor, is widely used for ADHD because it exhibits fewer adverse effects compared to conventional psychostimulants. However, little is known about the therapeutic mechanisms of ATX. ATX treatment significantly alleviated hyperactivity of pituitary adenylate cyclase-activating polypeptide (PACAP)-deficient (PACAP(-/-)) mice with C57BL/6J and 129S6/SvEvTac hybrid background. ATX also improved impaired novel object recognition memory and prepulse inhibition in PACAP(-/-) mice with CD1 background. The ATX-induced increases in extracellular noradrenaline and dopamine levels were significantly higher in the prefrontal cortex of PACAP(-/-) mice compared to wild-type mice with C57BL/6J and 129S6/SvEvTac hybrid background. These results suggest that ATX treatment-induced increases in central monoamine metabolism may be involved in the rescue of ADHD-related abnormalities in PACAP(-/-) mice. Our current study suggests that PACAP(-/-) mice are an ideal rodent model with predictive validity for the study of ADHD etiology and drug development. Additionally, the potential effects of differences in genetic background of PACAP(-/-) mice on behaviors are discussed.

Stress-induced ceramide generation and apoptosis via the phosphorylation and activation of nSMase1 by JNK signaling.

Neutral sphingomyelinase (nSMase) activation in response to environmental stress or inflammatory cytokine stimuli generates the second messenger ceramide, which mediates the stress-induced apoptosis. However, the signaling pathways and activation mechanism underlying this process have yet to be elucidated. Here we show that the phosphorylation of nSMase1 (sphingomyelin phosphodiesterase 2, SMPD2) by c-Jun N-terminal kinase (JNK) signaling stimulates ceramide generation and apoptosis and provide evidence for a signaling mechanism that integrates stress- and cytokine-activated apoptosis in vertebrate cells. An nSMase1 was identified as a JNK substrate, and the phosphorylation site responsible for its effects on stress and cytokine induction was Ser-270. In zebrafish cells, the substitution of Ser-270 for alanine blocked the phosphorylation and activation of nSMase1, whereas the substitution of Ser-270 for negatively charged glutamic acid mimicked the effect of phosphorylation. The JNK inhibitor SP600125 blocked the phosphorylation and activation of nSMase1, which in turn blocked ceramide signaling and apoptosis. A variety of stress conditions, including heat shock, UV exposure, hydrogen peroxide treatment, and anti-Fas antibody stimulation, led to the phosphorylation of nSMase1, activated nSMase1, and induced ceramide generation and apoptosis in zebrafish embryonic ZE and human Jurkat T cells. In addition, the depletion of MAPK8/9 or SMPD2 by RNAi knockdown decreased ceramide generation and stress- and cytokine-induced apoptosis in Jurkat cells. Therefore the phosphorylation of nSMase1 is a pivotal step in JNK signaling, which leads to ceramide generation and apoptosis under stress conditions and in response to cytokine stimulation. nSMase1 has a common central role in ceramide signaling during the stress and cytokine responses and apoptosis.

Measurement of mechanical strain on mandibular surface with mastication robot: influence of muscle loading direction and magnitude.

OBJECTIVES: To investigate the mechanical effects of mastication on the mandible, we developed computational controlled mastication robot system with human dry skull and analyzed the strain distribution on the mandibular bone surface. DESIGN: In the mastication robot, the mandible was suspended by eight wires, which simulated masticatory muscles. A non-linear spring damper generated viscoelastic properties, and tension sensors for simulation of jaw reflection to avoid unusual biting force were applied as a biological feedback mechanism. By using this robot system, various patterns of muscle loading (change of wire direction and magnitude) were performed. RESULTS: From the results, significant differences in the amount of principal strain and its distribution were demonstrated in each condition (ANOVA, post hoc test, and p < 0.05). The value of maximum principal strain ranged from 79.66 x 10(-6) [at anterior border of ramus (Buccal side), 128 N] to -1.42 x 10(-6) [at foramen mentale (Buccal side), 32 N]. CONCLUSION: These results suggested that the muscle loading generated the mechanical strain on the mandibular bone surface and it was affected by the changes in loading direction and magnitude.

Micro X-ray computed tomography analysis for the evaluation of asymmetrical condylar growth in the rat.

OBJECTIVES: To investigate the influence of forced lateral bite on mandibular growth, micro X-ray computed tomography (CT) was used for the purpose evaluating condylar cartilage and cancellous bone formation in 10 male Wister rats (3 weeks of age). SETTINGS AND SAMPLE POPULATION: The rats were divided into two groups--experimental and control. In experimental group, an inclined crown was cemented onto the maxillary incisors to produce 2.5 mm shift toward the left side during mastication. Right-left differences in whole mandibular length, mandibular height, condylar size, trabecular structure of the condylar head and three-dimensional (3-D) finite element analysis were assessed using 3-D images reconstructed from micro X-ray CT scans when the mice had reached 21 weeks. MEASUREMENTS AND RESULTS: Asymmetrical growth was found in the experimental group, in which the left condylar head became thicker and shorter than the right condylar head during development. When comparing the left and right condyles of the experimental animals, histomorphometric analysis from micro X-ray CT showed that the bone volume (BV) of the cancellous bone, the surface area of the cancellous bone (BS), the BS/BV ratio, the BV fraction (BV/TV), and the trabecular thickness and trabecular number were less for the right condyle than for the left condyle. CONCLUSIONS: These findings suggested that artificial changes in the mastication do influence the growth of condylar head, condylar bone trabecular structure, and mineralization.

Hemichrome formation observed in human haemoglobin A under various buffer conditions.

AIM: To observe hemichrome formation in human haemoglobin A under various buffer conditions. METHOD: Hemichrome formation of human oxyhaemoglobin A (HbO2) was studied spectrophotometrically in 0.1 m buffer at various temperatures and pH values. RESULTS: Following autoxidation in ferrous HbO2, it was evident that formation of hemichrome, which tends to precipitate, occurred at various stages during the course of the autoxidation reaction namely at initial, intermediate or final stages, depending on temperature and pH of the solution. By varying temperature of the solution from 35 to 55 degrees C and pH from 4.5 to 10.5, it is shown here that HbO2 exhibits high susceptibility for hemichrome formation and its occurrence is a function of pH, temperature and progress of autoxidation of HbO2. Unlike HbO2 and its separated haemoglobin chains, monomeric bovine heart myoglobin (MbO2) did not easily form hemichrome. CONCLUSION: These findings provide a clue on the crucial role of haemoglobin molecule for senescent cell recognition or homeostasis in the blood circulation.

Renal blood flow measurement with contrast-enhanced harmonic ultrasonography: evaluation of dopamine-induced changes in renal cortical perfusion in humans.

BACKGROUND: An accessible non-invasive method for evaluating renal regional blood flow in real time is highly desirable in the clinical setting. Recent progress in ultrasonography with microbubble contrast has allowed quantification of regional blood flow in animal models. AIMS: Goal ofthis study was to establish a convenient contrast--enhanced harmonic ultrasonography (CEHU) method for evaluating renal cortical blood flow in humans. METHODS: We carried out intermittent second harmonic imaging in 9 healthy volunteers. Pulse interval was progressively decreased from 4 s - 0.2 s during continuous venous infusion of the microbubble contrast agent. RESULTS: Pulse interval versus CEHU-derived acoustic intensity plots provided microbubble velocity (MV) and fractional vascular volume (FVV) during renal cortical perfusion in humans. Low-dose dopamine infusion (2 microg/min/kg) resulted in a significant increase in MV which correlated well with the increase in total renal blood flow (RBF) determined by a conventional study of p-aminohippurate clearance (C(PAH)) (r = 0.956, p < 0.0001). Although FVV was not significantly increased, alterations in CEHU-derived renal cortical blood flow calculated by the products of MV and FVV were also correlated with alterations in total RBF (r = 0.969, p < 0.0001). Thus, low-dose dopamine infusion increases renal cortical blood flow observed in CEHU, mainly by increasing MV. CONCLUSIONS: The present study shows that renal cortical blood flow in humans can be measured non-invasively by CEHU and that CEHU can be used for quantitatively evaluating changes induced by a therapeutic agent such as dopamine in flow velocity and in FVV.

Evaluation of PCR primers to screen for Streptococcus pneumoniae isolates and beta-lactam resistance, and to detect common macrolide resistance determinants.

Pneumococcal isolates (n = 148) from various countries (mostly from the USA) were tested by a primer set for PCR. Thirty-eight (86.4%) of the 44 penicillin G-susceptible isolates (MIC < or = 0.06 mg/L) had unaltered pbps, while six isolates (13.6%) had either one or two alterations in pbps. Of 47 penicillin G-resistant strains (MIC > or = 2 mg/L), 41 isolates (87.2%) had all three pbps altered, six isolates (12.8%) had altered pbp1a + 2x. Various combinations of altered pbp were seen in penicillin G-intermediate isolates. Prevalence of macrolide resistance genes mef(A) and erm(B) in isolates was clearly reflected by their MICs. All isolates were positive for lytA. The primers were useful for screening for Streptococcus pneumoniae and beta-lactam resistance, and for detection of common macrolide resistance determinants.

Angiotensin II signaling and HB-EGF shedding via metalloproteinase in glomerular mesangial cells.

BACKGROUND: Angiotensin II (Ang II) has been implicated in the development of glomerulosclerosis by stimulating fibronectin (FN) synthesis. The processing and release of heparin binding-endothelin growth factor (HB-EGF) are activated by protein kinase C (PKC) and Ca2+ signaling. We studied the roles of HB-EGF and endothelial growth factor (EGF) receptor (EGFR) in Ang II-induced FN expression using mesangial cells. METHODS: Mesangial cells were prepared from mouse kidneys by the explant method and cells were used at passages 4 and 5. RESULTS: Ang II stimulated FN mRNA levels dose-dependently with a maximal increase (3.4-fold) after 12 hours of incubation. This action was completely inhibited by PKC inhibitors and slightly blocked by Ca2+ chelating agents. FN mRNA accumulation by Ang II was abolished by tyrosine kinase inhibitors, a specific inhibitor for EGFR (AG1478) and extracellular signal-regulated kinase (ERK) inactivation. Addition of neutralizing anti-HB-EGF antibody, as well as pretreatment with heparin or the metalloproteinase inhibitor batimastat abolished induction of FN expression by Ang II. In mesangial cells stably transfected with a chimeric construct containing HB-EGF and alkaline phosphatase (ALP) genes, ALP activity in incubation medium was rapidly increased by Ang II (1.7-fold at 0.5 min) and reached a 4.1-fold increase at two minutes. Ang II phosphorylated EGFR (maximal at 2 min) and ERK (maximal at 8 min) in a PKC- and metalloproteinase-dependent manner. Ang II stimulated the expression and release of transforming growth factor-beta (TGF-beta) via EGFR-mediated signaling, and the released TGF-beta also contributed to Ang II-mediated FN expression via EGFR transactivation. CONCLUSIONS: Ang II-mediated FN expression was regulated by autocrine effects of HB-EGF and TGF-beta, suggesting a novel paradigm for cross-talk between Ang II and growth factor receptor signaling pathways.

Immunolocalization of vacuolar-type H+-ATPase, cathepsin K, matrix metalloproteinase-9, and receptor activator of NFkappaB ligand in odontoclasts during physiological root resorption of human deciduous teeth.

To investigate the cellular mechanisms of physiological root resorption in human deciduous teeth, the authors examined the immunocytochemical localization of vacuolar-type H+-ATPase, a lysosomal cysteine proteinase, cathepsin K, matrix metalloproteinase-9 (MMP-9), and receptor activator of NFKB ligand (RANKL) in odontoclasts. H+-ATPase, cathepsin K, and MMP-9 are the most important enzymes for decalcification of apatite crystals and degradation of type-I collagen. In addition, RANKL is one of the key regulatory molecules in osteoclast formation and functions. Odontoclasts developed extensive ruffled borders and clear zones apposed to the resorbing root dentine surfaces. On immunoelectron microscopy, the expression of vacuolar-type H+-ATPase was detected along the limiting membranes of pale vacuoles and the ruffled border membranes of odontoclasts. Cathepsin K in odontoclasts was localized within pale vacuoles, lysosomes, the extracellular canals of ruffled borders, and the underlying resorbing dentine surfaces. MMP-9 localization in odontoclasts was similar to those of cathepsin K. RANKL was detected in both mononuclear stromal cells and odontoclasts located on resorbing dentine surfaces. These results suggest that (1) odontoclasts are directly involved in decalcification of apatite crystals by active extrusion of proton ions mediated by H+-ATPase and (2) extracellular degradation of dentine type-I collagen by both cathepsin K and MMP-9, and (3) odontoclast differentiation and activity are regulated, at least in part, by RANKL, possibly produced by mononuclear stromal cells and odontoclasts themselves in the resorbing tissues. Thus, the cellular mechanisms of physiological root resorption appear to be quite similar to those of osteoclastic bone resorption.

Localization of receptor activator of NFkappaB ligand, RANKL, in periodontal tissues during experimental movement of rat molars.

The receptor activator of NFkappaB ligand, RANKL, is one of the key regulatory molecules in osteoclast formation and function. We examined RANKL localization in the periodontal tissues during experimental movement of rat molars. To produce orthodontic force, an elastic band was inserted between the upper first and second molars for 4 days, and the dissected maxillae were subjected to light and electron microscopic immunocytochemical examination for RANKL. Expression of RANKL protein was detected in osteoblasts, osteocytes, fibroblasts, and osteoclasts mostly located in resorption lacunae. In osteoblasts, osteocytes, and fibroblasts, RANKL localization was mainly observed in the cytoplasm, the cisternae of rough endoplasmic reticulum and along plasma membranes. In osteoclasts, RANKL was expressed along the ruffled, border membranes and in the cytoplasm, including the clear zone. These results suggest that during tooth movement, osteoclast differentiation and activation are regulated, at least in part, by RANKL, possibly produced by osteoblasts/stromal cells and osteoclasts themselves in the periodontal tissues.

Angiotensin II type 2 receptor inhibits epidermal growth factor receptor transactivation by increasing association of SHP-1 tyrosine phosphatase.

Angiotensin (Ang) II has 2 major receptor isoforms, Ang type 1 (AT(1)) and Ang type (AT(2)). AT(1) transphosphorylates epidermal growth factor receptor (EGFR) to activate extracellular signal-regulated kinase (ERK). Although AT(2) was shown to inactivate ERK, the action of AT(2) on EGFR activation remains undefined. Using AT(2)-overexpressing vascular smooth muscle cells from AT(2) transgenic mice, we studied these undefined actions of AT(2). Maximal ERK activity induced by Ang II was increased 1.9- and 2.2-fold by AT(2) inhibition, which was abolished by orthovanadate but not okadaic acid or pertussis toxin. AT(2) inhibited AT(1)-mediated EGFR tyrosine phosphorylation by 63%. The activity of SHP-1 tyrosine phosphatase was significantly upregulated 1 minute after AT(2) stimulation and association of SHP-1 with EGFR was increased, whereas AT(2) failed to tyrosine phosphorylate SHP-1. Stable overexpression of SHP-1-dominant negative mutant completely abolished AT(2)-mediated inhibition of EGFR and ERK activation. AT(1)-mediated c-fos mRNA accumulation was attenuated by 48% by AT(2) stimulation. Induction of fibronectin gene containing an AP-1 responsive element in its 5'-flanking region was decreased by 37% after AT(2) stimulation, corresponding to the results of gel mobility assay with the AP-1 sequence of fibronectin as a probe. These findings suggested that AT(2) inhibits ERK activity by inducing SHP-1 activity, leading to decreases in AP-1 activity and AP-1-regulated gene expression, in which EGFR dephosphorylation plays an important role via association of SHP-1.

A successfully treated case of disseminated tuberculosis-associated hemophagocytic syndrome and multiple organ dysfunction syndrome.

We report the case of a patient who presented with disseminated tuberculosis-associated hemophagocytic syndrome (HPS). A 40-year-old man was admitted because of fatigue, fever, and renal dysfunction. Chest radiograph and computed tomography scan showed diffuse reticulonodular shadow, and Mycobacterium tuberculosis was identified. Peripheral blood counts decreased rapidly, and bone marrow aspiration revealed hemophagocytosis by macrophages. Despite antituberculous and steroid pulse therapy, multiple organ dysfunction syndrome developed. After plasma exchange and continuous hemodiafiltration were started, hypercytokinemia and vital signs improved dramatically. Although disseminated tuberculosis-associated HPS carries a poor prognosis, acute blood purification may be an effective means of treating HPS involving multiple organ dysfunction syndrome.

Safety and availability of doxazosin in treating hypertensive patients with chronic renal failure.

Hypertension accelerates the progression of renal disease in patients with chronic renal failure. Doxazosin, an alpha1-antagonist, is an antihypertensive agent with a long half-life. In this study, 15 patients with chronic renal failure were treated only with doxazosin and diuretics for 6 months and their blood pressure, renal parameters and lipid profile were measured. The initial dose of doxazosin was 2 mg/day and it was titrated until blood pressure was normalized. The average dose was 5.6 mg/day. As expected, systolic and diastolic blood pressure were decreased with treatment (165/91 mmHg to 135/73 mmHg). The drop in blood pressure was associated with an increase in glomerular filtration and a decrease in plasma BUN and creatinine levels. Reduction in mean blood pressure and decrease in proteinuria had a significant positive correlation (r=0.048, p=0.007). Proteinuria was decreased from 1.8 mg/day to 1.3 mg/day with doxazosin treatment and triglycerides also decreased, while HDL-cholesterol was increased. No side effects were observed. These results indicate that doxazosin is an efficient depressor agent with renal protective actions and that higher doses of doxazosin can be safely given to patients with chronic renal failure.

Cortical bone mineral density in asymmetrical mandibles: a three-dimensional quantitative computed tomography study.

The three-dimensional distribution (3D) of the highest mineralized cortical bone was evaluated in 32 subjects between the ages of 8 and 30 years with asymmetrical mandibles using quantitative computed tomography (QCT). The geometrical distribution of the highest mineralized areas (> 1250 mg/cm3) representative of mandibular cortical bone was determined by 3D reconstruction of the images. The length of the mandible on each side was determined by defining a new linear measurement from the centre of the 3D reconstructed condyle to the midline of the symphysis as identified from a submental view. The cross-sectional areas of the masseter and medial pterygoid muscles were assessed from bilateral axial views through the middle of the muscles parallel to the Frankfort-Horizontal plane. Comparison between the lengths of the two mandibular sides (right-left = mm) indicated a range of asymmetries with an equal number of subjects with the left and right mandible longer. Comparison of the area of highest mineralized cortical bone between the right and left sides (R/L) to the ratio of the mandibular length (R/L) showed a high correlation coefficient (r = 0.629) suggesting that the shortest mandibular side had more highly mineralized bone. A comparison of the area of highest mineralized cortical bone between the right and left sides (R/L) to the ratio of cross-sectional areas of the muscles showed the highest correlation coefficient (r = 0.724) with the ipsilateral masseter muscle. These findings indicate that asymmetrical mandibles are associated with asymmetrical distributions of the highest mineralized cortical bone and that this is age dependent.

Growth hormone receptor gene variant and mandibular height in the normal Japanese population.

This study was aimed at quantitatively evaluating the relationship between craniofacial morphology and the Pro561Thr (P56IT) variant in the growth hormone receptor gene (GHR), which is considered to be an important factor in craniofacial and skeletal growth. The subjects were unrelated individuals in a normal Japanese population and consisted of 50 men and 50 women. With the use of genomic DNA extracted from whole blood, the GHR gene P56IT variant was detected by the polymerase chain reaction-restriction fragment length polymorphism method (with the restriction enzyme StuI). The relationships of the genotypes to body height and 5 linear measurements from lateral cephalograms were examined for evaluation of craniofacial morphology. The normal Japanese population without P56IT had a significantly greater mandibular ramus length (condylion-gonion) than did those with P56IT. This suggests that the GHR gene P56IT variant may be associated with mandibular height growth and can be a genetic marker for it. Further studies about such genetic markers may expand our understanding of the genetic control in craniofacial morphological determinants and help in the prediction of craniofacial growth.

Association of amino acid substitutions in penicillin-binding protein 3 with beta-lactam resistance in beta-lactamase-negative ampicillin-resistant Haemophilus influenzae.

The affinity of [(3)H]benzylpenicillin for penicillin-binding protein (PBP) 3A was reduced in 25 clinical isolates of beta-lactamase-negative ampicillin (AMP)-resistant (BLNAR) Haemophilus influenzae for which the AMP MIC was > or =1.0 microg/ml. The affinities of PBP 3B and PBP 4 were also reduced in some strains. The sequences of the ftsI gene encoding the transpeptidase domain of PBP 3A and/or PBP 3B and of the dacB gene encoding PBP 4 were determined for these strains and compared to those of AMP-susceptible Rd strains. The BLNAR strains were classified into three groups on the basis of deduced amino acid substitutions in the ftsI gene, which is thought to be involved in septal peptidoglycan synthesis. His-517, near the conserved Lys-Thr-Gly (KTG) motif, was substituted for Arg-517 in group I strains (n = 9), and Lys-526 was substituted for Asn-526 in group II strains (n = 12). In group III strains (n = 4), three residues (Met-377, Ser-385, and Leu-389), positioned near the conserved Ser-Ser-Asn (SSN) motif, were replaced with Ile, Thr, and Phe, respectively, in addition to the replacement with Lys-526. The MICs of cephem antibiotics with relatively high affinities for PBP 3A and PBP 3B were higher than those of AMP and meropenem for group III strains. The MICs of beta-lactams for H. influenzae transformants into which the ftsI gene from BLNAR strains was introduced were as high as those for the donors, and PBP 3A and PBP 3B showed decreased affinities for beta-lactams. There was no clear relationship between 7-bp deletions in the dacB gene and AMP susceptibility. Even though mutations in another gene(s) may be involved in beta-lactam resistance, these data indicate that mutations in the ftsI gene are the most important for development of resistance to beta-lactams in BLNAR strains.

A clinical and histological evaluation of titanium mini-implants as anchors for orthodontic intrusion in the beagle dog.

The aim of this study was to determine the anchorage potential of the titanium mini-implant for orthodontic intrusion of the mandibular posterior teeth. Six mini-implants were surgically placed around the mandibular third premolars on each side in 3 adult male beagle dogs. On the buccal site, three mini-implants were placed distal to the apex of the distal root of the third premolar, at the interradicular septa of the third premolar, and mesial to the apex of the mesial root of the third premolar, as linearly as possible. The same procedure was performed at the lingual site on both sides of the mandibular third premolars in each dog. Bilateral interradicular mini-implants on both the buccal and the lingual sites were used as the anchorage for the intrusion of the third premolars (loaded implants) and the other mini-implants were used as control (unloaded) implants. In 6 weeks, an intrusive force (150 g) was applied between the interradicular implants on the buccal and the lingual sites by closed coil springs run across the crowns of the third premolars. After 12 to 18 weeks of orthodontic intrusion, the animals were killed and their mandibles were dissected and prepared for histologic and fluorescent observation. The results indicated that the mandibular third premolars intruded 4.5 mm, on average, after 12 to 18 weeks of orthodontic force application, with mild root resorption at the furcation area as well as the root apex. All the mini-implants remained stable during orthodontic tooth movement without any mobility or displacement. The morphometrical findings indicated that the calcification of the peri-implant bone on the loaded implants was equal to or slightly greater than those of the controls. In addition, 6 of the 36 mini-implants were removed after tooth movement, and all of them were easily removed with a screwdriver. These findings suggest that mini-implants are effective tools for the anchorage of orthodontic intrusion in beagle dogs.