Brief communication: body composition and hidden obesity in people living with HIV on antiretroviral therapy.

BACKGROUND: Increased incidence of lifestyle diseases as side-effects of antiretroviral therapy (ART) have been reported in people living with HIV (PLWH). Few studies have evaluated obesity and hidden obesity in Japanese PLWH and their association with ART. In order to provide more appropriate drug selection and lifestyle guidance, we investigated the relationship between the effects of HIV infection and ART on the body composition of Japanese PLWH. METHODS: PLWH who visited the outpatient clinic and had body composition measured using the body composition analyzer InBody 570 were included in this study. Medications, comorbidities, and blood test data were obtained. Body mass index (BMI), body fat percentage, and skeletal muscle mass index (SMI) were measured. RESULTS: In this study, 543 patients were included. Based on body shape, patients were classified into a thin group (13), normal weight group (14), hidden obesity group (158), apparent obesity group (14), and obesity group (218). Compared with the normal weight group, the hidden obesity group had a higher prevalence of comorbidities and a lower SMI. CONCLUSIONS: PLWH are more likely to have obesity than the general population, indicating that hidden obesity is common even among those with a normal BMI. It is important to measure body fat percentage along with body weight, as hidden obesity can be missed. Further investigation of the effects of ART on body composition is needed.

Laminar-type gratings overcoated with carbon-based materials to enhance analytical sensitivity of flat-field emission spectrograph in the VUV region.

Laminar-type spherical diffraction gratings overcoated with carbon-based materials were designed, fabricated, and evaluated for the purpose of enhancing the analytical sensitivity of the flat-field spectrograph in a vacuum ultraviolet region of 35-110 eV. As the design benchmark for numerical calculations, diffraction efficiency (DE) and spectral flux, which are defined by the product of the DE and numerical aperture and correlate with the analytical sensitivity of the spectrograph, were used. To simplify the feasibility study on the overcoating effects, we assumed a laminar-type grating having a grating constant of 1/1000 mm and coated with a Au layer of 30.0 nm thickness and an incidence angle of 84.0°. The optimized groove depth and duty ratio were 30.0 nm and 0.3, respectively. In addition, the optimum thicknesses of the overcoating layer were 44, 46, 24, and 30 nm for B4C, C, diamond-like-carbon, and SiC, respectively. Based on these results, we have fabricated a varied-line-spacing holographic grating overcoated with B4C with a thickness of 47 nm. For the experimental evaluation, we used the light source of Mg-L and Al-L emissions excited by the electron beam generated from an electron microscope, an objective flat-field spectrograph, and a CCD imaging detector. The experimental results showed that the spectrograph employing a new grating overcoated with the B4C layer indicated almost the same spectral resolution and 2.9-4.2 times higher analytical sensitivity compared with those obtained with a previously designed Au-coated grating having a grating constant of 1/1200 mm and used at an incidence of 86.0°.

Epibiotic fauna of the Antarctic minke whale as a reliable indicator of seasonal movements.

Antarctic minke whales, Balaenoptera bonaerensis, breed in tropical and temperate waters of the Southern Hemisphere in winter and feed in Antarctic grounds in the austral summer. These seasonal migrations could be less defined than those of other whale species, but the evidence is scanty. We quantitatively describe the epibiotic fauna of Antarctic minke whales and explore its potential to trace migrations. Seven species were found on 125 out of 333 examined Antarctic minke whales captured during the last Antarctic NEWREP-A expedition in the Southern Ocean: the amphipod Balaenocyamus balaenopterae (prevalence = 22.2%), the copepod Pennella balaenoptera (0.6%); three coronulid, obligate barnacles, Xenobalanus globicipitis (11.1%), Coronula reginae (8.7%), C. diadema (0.9%); and two lepadid, facultative barnacles, Conchoderma auritum (9.0%) and C. virgatum (0.3%). Species with prevalence > 8% exhibited a modest increase in their probability of occurrence with whale body length. Data indicated positive associations between coronulid barnacles and no apparent recruitment in Antarctic waters. All specimens of X. globicipitis were dead, showing progressive degradation throughout the sampling period, and a geographic analysis indicated a marked drop of occurrence where the minimum sea surface temperature is < 12 °C. Thus, field detection -with non-lethal methodologies, such as drones- of coronulid barnacles, especially X. globicipitis, on whales in the Southern Ocean could evince seasonal migration. Future investigations on geographical distribution, growth rate, and degradation (for X. globicipitis) could also assist in timing whales' migration.

Resurrecting the ancient glow of the fireflies.

The color of firefly bioluminescence is determined by the structure of luciferase. Firefly luciferase genes have been isolated from more than 30 species, producing light ranging in color from green to orange-yellow. Here, we reconstructed seven ancestral firefly luciferase genes, characterized the enzymatic properties of the recombinant proteins, and determined the crystal structures of the gene from ancestral Lampyridae. Results showed that the synthetic luciferase for the last common firefly ancestor exhibited green light caused by a spatial constraint on the luciferin molecule in enzyme, while fatty acyl-CoA synthetic activity, an original function of firefly luciferase, was diminished in exchange. All known firefly species are bioluminescent in the larvae, with a common ancestor arising approximately 100 million years ago. Combined, our findings propose that, within the mid-Cretaceous forest, the common ancestor of fireflies evolved green light luciferase via trade-off of the original function, which was likely aposematic warning display against nocturnal predation.

Ring and unimodal angular-frequency distribution of THz emission from two-color femtosecond plasma spark.

We study angular and frequency-angular distributions of the terahertz (THz) emission of the low-frequency region (0.3-3 THz) from a two-color femtosecond plasma spark experimentally and in three-dimensional numerical simulations. We investigate the dependence of the angular shapes of the THz radiation on focusing conditions and pulse durations by using two laser facilities (pulse durations 35 and 150 fs) for different focusing geometries. Our experiments and simulations show that decrease in the numerical aperture from NA ≈0.2 to NA ≈0.02 results simultaneously in (I) squeezing of the THz angular distribution and (II) formation of the bright conical emission in the THz range. The moderate focusing NA ≈0.05, which forms the relatively narrow unimodal THz angular distribution, is identified as optimal in terms of angular divergence. Numerical simulations with carrier wave resolved show that bright THz ring structures appear at the frequencies ≥2 THz for longer focuses (NA ≈0.02), while for optimal focusing conditions NA ≈0.05 the conical emission develops at THz frequencies higher than 10 THz.

Impact of video games on plasticity of the hippocampus.

The hippocampus is critical to healthy cognition, yet results in the current study show that action video game players have reduced grey matter within the hippocampus. A subsequent randomised longitudinal training experiment demonstrated that first-person shooting games reduce grey matter within the hippocampus in participants using non-spatial memory strategies. Conversely, participants who use hippocampus-dependent spatial strategies showed increased grey matter in the hippocampus after training. A control group that trained on 3D-platform games displayed growth in either the hippocampus or the functionally connected entorhinal cortex. A third study replicated the effect of action video game training on grey matter in the hippocampus. These results show that video games can be beneficial or detrimental to the hippocampal system depending on the navigation strategy that a person employs and the genre of the game.

Coherent microwave generation by spintronic feedback oscillator.

The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ. Any fluctuation of the free layer magnetization is converted into oscillating voltage via the tunneling magneto-resistance effect and is fed back into the MTJ by the CPW through inductive coupling. As a result of this feedback, the magnetization of the free layer can be driven into a continual precession. The combination of MTJ and CPW behaves similar to a laser system and outputs a stable rf power with quality factor exceeding 10,000.

Bone morphogenetic protein 7 induces cementogenic differentiation of human periodontal ligament-derived mesenchymal stem cells.

Bone morphogenetic protein 7 (BMP-7) is a multifunctional differentiation factor that belongs to the transforming growth factor superfamily. BMP-7 induces gene expression of protein tyrosine phosphatase-like, member A/cementum attachment protein (PTPLA/CAP) and cementum protein 1 (CEMP1), both of which are markers of cementoblasts and cementocytes. In the previous study, we reported that BMP-7 treatment enhanced PTPLA/CAP and CEMP1 expression in both normal and immortal human periodontal ligament (PDL) cells. To elucidate the molecular mechanisms of the gene expression of these molecules, in this study, we identified a functional transcription activator binding region in the promoter region of PTPLA/CAP and CEMP1 that is responsive to BMP signals. Here, we report that some short motifs termed GC-rich Smad-binding elements (GC-SBEs) that are located in the human PTPLA/CAP promoter and CEMP1 promoter are BMP-7 responsive as analyzed with luciferase promoter assays. On the other hand, we found that transcription of Sp7/Osterix and PTPLA/CAP was up-regulated after 1 week of BMP-7 treatment on purified normal human PDL cells as a result of gene expression microarray analysis. Furthermore, transcription of Sp7/Osterix, runt-related transcription factor 2 (RUNX2), and alkaline phosphatase (ALP) was up-regulated after 2 weeks of BMP-7 treatment, whereas gene expression of osteo/odontogenic markers such as integrin-binding sialoprotein (IBSP), collagen, type I, alpha 1 (COL1A1), dentin matrix acidic phosphoprotein 1 (DMP1), and dentin sialophosphoprotein (DSPP) was not up-regulated in purified normal or immortal human PDL cells as a result of qRT-PCR. The results suggest that BMP-7 mediates cementogenesis via GC-SBEs in human PDL cells and that its molecular mechanism is different from that for osteo/odontogenesis.

Porphyromonas gingivalis C-terminal signal peptidase PG0026 and HagA interact with outer membrane protein PG27/LptO.

Outer membrane protein PG27 is essential for secretion/maturation of conserved C-terminal domain (CTD) proteins such as gingipains, HagA, and PG0026. To determine the binding partner(s) of PG27, we used a Porphyromonas gingivalis mutant strain, 83K48, which expressed functional histidine-tagged PG27. Purification of histidine-tagged PG27 from 83K48 found that 136-kDa and 264-kDa proteins accompanied histidine-tagged PG27. Mass spectrometry revealed the 136-kDa protein and 264-kDa protein to be PG0026 and PG1837 (HagA), respectively. PG0026 is a C-terminal signal peptidase which cleaves the CTDs of other CTD proteins. A cross-linking and a native electrophoresis studies suggested the interaction between histidine-tagged PG27 and HagA and the interaction between histidine-tagged PG27 and PG0026. We constructed Porphyromonas gingivalis gene disrupting mutants, and characterized them. PG0026 was required for the full activities of gingipains, whereas HagA was not. A mutation disrupting PG0026 affected localization of PG27, but a mutation disrupting PG1837 showed little effect on the expression and localizations of PG27 and PG0026. To determine the functional role of HagA, we used PG1837-disruptant 83K54 which expressed functional histidine-tagged PG27. Histidine-tagged PG27 in 83K54 was co-purified with not only PG0026 but also several contaminated proteins. These results suggest that PG0026 interacts with PG27 in the absence of HagA, and that the binding state of a PG27-PG0026 complex was affected and stabilized by HagA. Taken together, these data suggest that secreted PG0026 anchors to the cell by interacting with PG27, is stabilized by HagA, and functions in processing of other CTD proteins such as gingipains.

Impact of excision repair cross-complementing gene 1 (ERCC1) on the outcomes of patients with advanced gastric cancer: correlative study in Japan Clinical Oncology Group Trial JCOG9912.

BACKGROUND: Since the best chemotherapy regimen for each patient with advanced gastric cancer is uncertain, we aimed to identify molecular prognostic or predictive biomarkers from biopsy specimens in JCOG9912, a randomized phase III trial for advanced gastric cancer. PATIENTS AND METHODS: Endoscopic biopsy specimens from primary lesions were collected in 445 of 704 randomized patients in JCOG9912. We measured the mRNA expression of excision repair cross-complementing group 1 (ERCC1), thymidylate synthase, dihydropyrimidine dehydrogenase, and five other genes, then, categorized them into low and high groups relative to the median, and examined whether gene expression was associated with efficacy end point. RESULTS: Multivariate analyses showed that high ERCC1 expression [HR 1.37; 95% confidence interval (CI) 1.08-1.75; P = 0.010], performance status ≥ 1 (HR 1.45; 95% CI 1.13-1.86; P = 0.004), and number of metastatic sites ≥ 2 (HR 1.66; 95% CI 1.28-1.86; P < 0.001) were associated with a poor prognosis, and recurrent disease (versus unresectable; HR 0.75; 95% CI 0.56-1.00; P = 0.049) was associated with a favorable prognosis. None of these molecular factors were a predictive marker for choosing irinotecan plus cisplatin or 5-fluorouracil rather than S-1. CONCLUSION: These correlative analyses suggest that ERCC1 is an independent prognostic factor for overall survival in the first-line treatment of gastric cancer. CLINICAL TRIAL NUMBER: C000000062, www.umin.ac.jp.

Changes in beef sensory traits as somatic-cell-cloned Japanese black steers increased in age from 20 to 30 months.

Changes in sensory traits of longissimus muscle (LM) from 20-30-month-old cattle were investigated using somatic cell clones of Japanese black steers slaughtered at 20-, 25- and 30-months-old (n=3, 4 and 4 respectively). The fat content of LM samples at 20, 25 and 30 months were 23.7, 38.7 and 41.1%, respectively. Soluble collagen content and collagen solubility at 20 months was greater than at 25 and 30 months. In terms of sensory traits, initial tenderness and juiciness at 25 months was greater than at 20 months, and fattiness at 25 and 30 months was greater than at 20 months. These results demonstrate that the changes in physicochemical traits of beef accompanying the differences in slaughter age affect the sensory traits although the desirable effects of the sensory traits do not continue throughout the entire fattening period.

Control of magnetic dipole terahertz radiation by cavity-based phase modulation.

Although it is well accepted that the ultrafast manipulation of spins or magnetization in solid promises potential applications in coherent terahertz (THz) radiation source, spintronics and quantum information processing, their performance is significantly limited by the weak coupling between radiation field and magnetic dipole oscillation. For such 'weak' magnetic system, we propose an effective and simple route based on the cavity-based phase modulation technique towards the efficient energy extraction, demonstrated via controlling the magnetic dipole THz radiation generated in the nonlinear Raman process from antiferromagnetic (AFM) NiO. An asymmetric coupled Fabry-Pérot (FP) cavity is constituted by simply placing a metallic planar mirror in the vicinity of a NiO slab. The energy-extraction (THz radiation) can be effectively manipulated by changing the NiO-mirror distance to modulate the phase relation between the magnetic wave and the induced magnetization in NiO. The distinct radiation control can be observed and the experiments are well explained by numerically analyzing the radiation dynamics that highlights the role of phase modulation during the radiation process.

Analysis of Porphyromonas gingivalis PG27 by deletion and intragenic suppressor mutation analyses.

PG27 is required for secretion of virulence factor gingipains, and has recently been proposed as LptO, which is involved in O-deacylation of lipopolysaccharide. In the present study, a predicted 14 anti-parallel ß-strand structure of PG27 was ascertained. Deletion study showed that the region from Asp382 to the C-terminal His391 of PG27 is dispensable for the function of PG27. Analysis of C-terminal deletion mutants revealed that the region in strand S14 (Asn369-Gly385) is important for activity. Of the gingipain-defective mutants, ΔThr378-His391 and ΔPhe377-His391 produced amounts of PG27 comparable to those produced by wild-type cells, suggesting that Thr378-Phe381 contains essential residues for the function of PG27. In contrast, ΔPhe381-His391, ΔAla380-His391, ΔLeu379-His391 and ΔArg376-His391 produced no detectable PG27. The defects of the ΔAla380-His391 mutant were suppressed by changing either Ala346 or Ala359 of PG27 to valine. Importantly, Ala346 and Ala359 are located close to Leu379 in the structural model of PG27. A359V compensated for the instability of PG27, but not the gingipain-defective phenotypes, of other deletion mutants tested, suggesting that Ala380 and Phe381 of PG27 are important for the stability of PG27. Lastly, we found that the C-terminal region of PG27 may be located in the periplasm. Taken together, these findings fit well with a predicted ß-barrel structure model for PG27, and show that strand S14 is important for its function.

Development of rapid oral bacteria detection apparatus based on dielectrophoretic impedance measurement method.

In this study, a bacteria detection apparatus based on dielectrophoretic impedance measurement (DEPIM) method was demonstrated for rapid evaluation of oral hygiene. The authors integrated a micro electrode chip on which bacteria were captured by dielectrophoresis (DEP), an AC voltage source to induce DEP force, and an impedance measurement circuit to a portable instrument that enables rapid and automated oral bacterial inspection in hospitals and clinics. Special considerations have been made on effects of high electrical conductivity of oral samples on DEP force and DEPIM results. It was shown experimentally and theoretically that using a higher electric field frequency for the DEP bacteria trap and the impedance measurement could realise DEPIM application to bacteria inspection from oral samples with higher conductivity. Based on these investigations, the authors optimised the frequency condition of the DEPIM suitable for inspecting an oral sample along with the design and development of a portable DEPIM apparatus for on-site inspection of oral bacteria. Under the optimised frequency condition, DEPIM results were in good agreement with the conventional culture method showing significant applicability of the DEPIM apparatus for practical rapid oral bacteria inspection.

Effects of open lung approach policy on mechanical ventilation duration in postoperative patients with chronic thromboembolism with pulmonary hypertension: a case-matched study.

Patients with chronic thromboembolism with pulmonary hypertension (CTEPH) often develop severe hypoxaemia after pulmonary thromboendarterectomy. There is reluctance to apply high positive end-expiratory pressure (PEEP) to those patients, whereas high PEEP is important for acute hypoxaemic respiratory failure due to alveolar collapse. Open lung approach (OLA) policy, a combination of recruitment manoeuvre and PEEP titration, may improve oxygenation and lung mechanics in acute hypoxaemic respiratory failure, but the effect of OLA on the outcome is unknown. We designed a case-matched, retrospective study to investigate whether OLA policy improved the outcome of postoperative patients with CTEPH. Among 113 postoperative patients with CTEPH, 40 were chosen before and after the introduction of an OLA policy to create 1:1 ratio of case-match according to gender, age and preoperative total pulmonary resistance index (conventional treatment group vs. OLA group). In the OLA group, recruitment manoeuvre was applied and then PEEP was titrated to maintain oxygenation every 12 hours. Gas exchange and duration of mechanical ventilation were compared between the groups. The OLA group showed higher PaO2/FiO2 ratio at 12 hours after the surgery than the conventional group (P = 0.0021). In the OLA group, duration of mechanical ventilation was shorter than the conventional treatment group (median, 23.5 hours vs. 43 hours, P = 0.0064). The OLA group showed lower cardiac index, higher pulmonary artery pressure and higher total pulmonary resistance index after the surgery than the conventional group. The introduction of the OLA policy may have shortened mechanical ventilation duration despite what appeared to be less favorable early postoperative hemodynamics in patients after the surgery for CTEPH.

Risk factors for portal venous thrombosis after splenectomy in patients with cirrhosis and portal hypertension.

BACKGROUND: Portal venous thrombosis (PVT) is a potentially fatal complication following splenectomy. Its mechanisms and risk factors are poorly understood, especially in patients with cirrhosis and portal hypertension. This study investigated risk factors for PVT following splenectomy in such patients. METHODS: All consecutive patients with cirrhosis who underwent splenectomy in Kyushu University Hospital between 1998 and 2004 were included in this retrospective study. They were divided into two groups based on the presence or absence of postoperative PVT. Preoperative and operative factors were compared, and the relationships between formation of PVT and its independent variables were analysed. In some cases, portal venous flow was measured before and after splenectomy using duplex Doppler ultrasonography. RESULTS: PVT developed after surgery in 17 (24 per cent) of 70 patients studied. Multivariable analysis showed that increased splenic vein diameter and low white cell count were significant independent risk factors for PVT. Portal venous flow after splenectomy was greatly reduced in the PVT group, but not in patients without PVT. CONCLUSION: Large splenic vein diameter and low white cell count are independent risk factors for PVT after splenectomy in patients with cirrhosis and portal hypertension.

Development of a colon endoscope robot that adjusts its locomotion through the use of reinforcement learning.

PURPOSE: Fibre optic colonoscopy is usually performed with manual introduction and advancement of the endoscope, but there is potential for a robot capable of locomoting autonomously from the rectum to the caecum. A prototype robot was designed and tested. METHODS: The robot colonic endoscope consists in a front body with clockwise helical fin and a rear body with anticlockwise one, both connected via a DC motor. Input voltage is adjusted automatically by the robot, through the use of reinforcement learning, determining speed and direction (forward or backward). RESULTS: Experiments were performed both in-vitro and in-vivo, showing the feasibility of the robot. The device is capable of moving in a slippery environment, and reinforcement learning algorithms such as Q-learning and SARSA can obtain better results than simply applying full tension to the robot. CONCLUSIONS: This self-propelled robotic endoscope has potential as an alternative to current fibre optic colonoscopy examination methods, especially with the addition of new sensors under development.

Culture of bovine embryos in polyester mesh sections: the effect of pore size and oxygen tension on in vitro development.

The purpose of this study was to assess the feasibility of polyester mesh culture for the in vitro production of bovine embryos, as polyester mesh is an alternative way for tracking individual embryos throughout culture using time-lapse cinematography (TLC). Bovine embryos were isolated during in vitro culture using sections of three different polyethylene terephthalate (PET) mesh products. In vitro matured and fertilized bovine oocytes were cultured in the 217 × 217, 230 × 230 or 238 × 238-µm openings of PET mesh sections or in simple micro-drops (control) for 7 days under either 20% or 5% O(2) tensions. No difference in embryo developmental rates was found between the culture groups in terms of cleavage, blastocyst formation and blastocyst expansion irrespective of O(2) tension. In contrast, under 20% O(2) tension, blastocysts that developed in PET mesh with 217 × 217-µm opening had significantly higher numbers of total and trophectoderm (TE) cells than control embryos; however, the numbers and proportions of inner cell mass (ICM) cells did not differ. Under 5% O(2) tension, no difference was found among the culture groups in the numbers of total, ICM and TE cells in embryos. All three PET mesh products investigated in this study were proven to be effective to prevent embryo movement. The results demonstrate that bovine embryos can be cultured in PET mesh sections without negative side-effects and suggest that embryo distance determined by the mesh affects embryo quality at atmospheric oxygen tension. Polyethylene terephthalate mesh with 217 × 217-µm openings was found to be the most suitable for further application in TLC.

Development of a robotic endoscope that locomotes in the colon with flexible helical fins.

The purpose of this study was to develop a robotic endoscope that is low invasive, easy to operate and capable of locomotion from the rectum to the appendix in the human body. We believe that it would contribute to relieving pain in patients. We therefore developed a robotic endoscope that consists of a front and rear body with clockwise and anticlockwise helical fins, respectively. The front and rear bodies are connected via a DC motor. This robot moves forward in the colon by rotating the front body in the clockwise direction and the rear body in the anticlockwise direction. In addition, the radius of each helical fin can be changed by blowing air into a balloon implemented under each fin using an air compressor. Before experiments with animals, we performed experiments to evaluate the mechanical performance and safety of the robot. We confirmed that the maximum radius of the fins was less than the maximum radius of the colon by blowing air continuously into the balloons. We then confirmed that the robot can locomote in the colon without invasion of scratch and make short hole by performing an in-vivo experiment in live swine.

Participation of the secreted dipeptidyl and tripeptidyl aminopeptidases in asaccharolytic growth of Porphyromonas gingivalis.

BACKGROUND AND OBJECTIVE: Porphyromonas gingivalis secretes gingipains, endopeptidases essential for the asaccharolytic growth of this bacterium. P. gingivalis also secretes dipeptidyl aminopeptidases (DPPIV and DPP-7) and a tripeptidyl aminopeptidase (PTP-A), although their role in asaccharolytic growth is unclear. The present study was carried out to elucidate the role of these dipeptidyl/tripeptidyl aminopeptidases on the asaccharolytic growth of P. gingivalis. MATERIAL AND METHODS: Knockout mutants for the DPPIV (dpp), dpp7 and/or PTP-A genes were constructed. Brain-heart infusion medium supplemented with sterile hemin and menadione (BHIHM) was used as a complex medium, and the minimal medium used was GA, in which the sole energy source was a mixture of immunoglobulin G and bovine serum albumin. Growth of P. gingivalis was monitored by measuring the optical density of the culture. RESULTS: All knockout mutants for DPPIV, dpp7 and PTP-A grew as well as strain W83 in BHIHM. In GA, growth of single-knockout and double-knockout mutants was similar to that of W83, whereas growth of a triple-knockout mutant (83-47A) was reduced. We purified recombinant DPPIV and recombinant PTP-A from recombinant Escherichia coli overproducers, and purified DPP-7 from the triple-knockout mutant 83-4A. GA supplemented with the three purified dipeptidyl/tripeptidyl aminopeptidases supported the growth of 83-47A. CONCLUSION: DPPIV, DPP-7 and PTP-A contribute to the normal growth of P. gingivalis by cleaving substrate peptides into short-chain polypeptides that are efficient energy sources for P. gingivalis.