Effects of doxycycline on heartworm embryogenesis, transmission, circulating microfilaria, and adult worms in microfilaremic dogs

Tetracycline treatment of animals or humans infected with filariae that harbor Wolbachia endosymbionts blocks further embryogenesis, and existing microfilariae gradually die. This treatment also kills developing larvae and has a slow-kill effect on adult filariae, all presumably due to elimination of the Wolbachia. Also, Dirofilaria immitis microfilariae in blood collected from dogs up to 25 days after the last dose of doxycycline developed to infective L3 that were normal in appearance and motility in mosquitoes but did not continue to develop or migrate normally after subcutaneous (SC) injection into dogs. The present study was designed to determine whether heartworm microfilariae collected at later times after treatment would regain the ability to continue normal development in a dog. The study also was expected to yield valuable data on the effects of treatment on microfilariae and antigen levels and adult worms. The study was conducted in 16 dogs as two separate replicates at different times. A total of five dogs (two in Replicate A and three in Replicate B) infected either by SC injection of L3 or intravenous transplantation of adult heartworms were given doxycycline orally at 10mg/kg twice daily for 30 days, with three untreated controls. Microfilarial counts in the five treated dogs gradually declined during the 12-13 months after treatment initiation. Two dogs were amicrofilaremic before necropsy and three had 13 or fewer microfilariae/ml. Only one treated dog was negative for heartworm antigen before necropsy. Overall, treated dogs generally had fewer live adult heartworms than controls, and most of their live worms were moribund. All three control dogs remained positive for microfilariae and antigen and had many live worms. L3 from mosquitoes fed on blood collected 73-77 or 161-164 days after initiation of doxycycline treatments were injected SC into five dogs. None of the dogs injected with L3 from mosquitoes fed on blood from doxycycline-treated dogs were ever positive for microfilariae or antigen, and none had worms at necropsy; three control dogs were positive for microfilariae and antigen and had many live worms. These data indicate that doxycycline treatment of microfilaremic dogs gradually reduces numbers of microfilariae and blocks further transmission of heartworms. This latter effect should be highly effective in reducing the rate of selection of heartworms with genes that confer resistance to macrocyclic lactone preventives and microfilaricides. The data also suggest that doxycycline has a slow-kill effect on adult heartworms.

Susceptibility of clinical Moraxella catarrhalis isolates in British Columbia to six empirically prescribed antibiotic agents

Moraxella catarrhalis has the ability to cause upper and lower respiratory tract infections. Typically, antibiotic susceptibility is not tested on isolation of the organism, but a reference document summarizing predicted susceptibilities is provided. The authors of this article aimed to determine the current susceptibilities of this organism in British Columbia, to update the predicted susceptibilites and ensure that appropriate antibiotic prescribing will occur.

BACKGROUND:

Moraxella catarrhalis is a commensal organism of the respiratory tract that has emerged as an important pathogen for a variety of upper and lower respiratory tract infections including otitis media and acute exacerbations of chronic bronchitis. Susceptibility testing of M catarrhalis is not routinely performed in most diagnostic laboratories; rather, a comment predicting susceptibility based on the literature is attached to the report. The most recent Canadian report on M catarrhalis antimicrobial susceptibility was published in 2003; therefore, a new study at this time was of interest and importance.

OBJECTIVE:

To determine the susceptibility of M catarrhalis isolates from British Columbia to amoxicillin-clavulanate, doxycycline, clarithromycin, cefuroxime, levofloxacin and trimethoprimsulfamethoxazole.

METHODS:

A total of 117 clinical M catarrhalis isolates were isolated and tested from five Interior hospitals and two private laboratory centres in British Columbia between January and December 2012. Antibiotic susceptibility of M catarrhalis isolates was characterized using the Etest (E-strip; bioMérieux, USA) according to Clinical Laboratory Standards Institute guidelines.

RESULTS:

All isolates were sensitive to amoxicillin-clavulanate, doxycycline, clarithromycin, levofloxacin and trimethoprimsulfamethoxazole. One isolate was intermediately resistant to cefuroxime, representing a 99.15% sensitivity rate to the cephem agent. Cefuroxime minimum inhibitory concentrations (MICs) inhibiting 50% and 90% of organisms (MIC50 and MIC90) were highest among the antibiotics tested, and the MIC90 (3 μg/mL) of cefuroxime reached the Clinical Laboratory Standards Institute breakpoint of susceptibility.

DISCUSSION:

The antibiotic susceptibility of M catarrhalis isolates evaluated in the present study largely confirms the findings of previous surveillance studies performed in Canada. Cefuroxime MICs are in the high end of the sensitive range and the MIC50 and MIC90 observed in the present study are the highest ever reported in Canada.

CONCLUSION:

Although cefuroxime MICs in M catarrhalis are high, all agents tested showed antimicrobial activity, supporting their continued therapeutic and empirical use.

Co-administration of the flavanol (-)-epicatechin with doxycycline synergistically reduces infarct size in a model of ischemia reperfusion injury by inhibition of mitochondrial swelling

(-)-Epicatechin (EPI) is cardioprotective in the setting of ischemia/reperfusion (IR) injury and doxycycline (DOX) is known to preserve cardiac structure/function after myocardial infarction (MI). The main objective of this study was to examine the effects of EPI and DOX co-administration on MI size after IR injury and to determine if cardioprotection may involve the mitigation of mitochondrial swelling. For this purpose, a rat model of IR was used. Animals were subjected to a temporary 45 min occlusion of the left anterior descending coronary artery. Treatment consisted of a single or double dose of EPI (10 mg/kg) combined with DOX (5 mg/kg). The first dose was given 15 min prior to reperfusion and the second 12 h post-MI. The effects of EPI +/- DOX on mitochondrial swelling (i.e. mPTP opening) were determined using isolated mitochondria exposed to calcium overload and data examined using isobolographic analysis. To ascertain for the specificity of EPI effects on mitochondrial swelling other flavonoids were also evaluated. Single dose treatment reduced MI size by ~46% at 48 h and 44% at three weeks. Double dosing evidenced a synergistic, 82% reduction at 3 weeks. EPI plus DOX also inhibited mitochondrial swelling in a synergic manner thus, possibly accounting for the cardioprotective effects whereas limited efficacy was observed with the other flavonoids. Given the apparent lack of toxicity in humans, the combination of EPI and DOX may have clinical potential for the treatment of myocardial IR injury.

Myocardial matrix metalloproteinase-2: inside out and upside down

Since their inaugural discovery in the early 1960s, matrix metalloproteinases (MMPs) have been shown to mediate multiple physiological and pathological processes. In addition to their canonical function in extracellular matrix (ECM) remodeling, research in the last decade has highlighted new MMP functions, including proteolysis of novel substrates beyond ECM proteins, MMP localization to subcellular organelles, and proteolysis of susceptible intracellular proteins in those subcellular compartments. This review will provide a comparison of the extracellular and intracellular roles of MMPs, illustrating that MMPs are far more interesting than the one-dimensional view originally taken. We focus on the roles of MMP-2 in cardiac injury and repair, as this is one of the most studied MMPs in the cardiovascular field. We will highlight how understanding all dimensions, such as localization of activity and timing of interventions, will increase the translational potential of research findings. Building upon old ideas and turning them inside out and upside down will help us to better understand how to move the MMP field forward.

In vitro Synergism between Chloroquine and Antibiotics against Orientia tsutsugamushi

BACKGROUND

To investigate whether chloroquine enhances the effect of antibiotics against Orientia tsutsugamushi, the causative organism of scrub typhus, we compared the effect of antibiotics in combination with chloroquine with the effect of antibiotics alone in vitro.

MATERIALS AND METHODS

The Boryong or AFSC-4 strain was inoculated into ECV304 cells, and incubated in medium containing doxycycline (4 µg/mL), rifampin (4 µg/mL), azithromycin (0.5 µg/mL), chloroquine (1 µg/mL), and each of these antibiotics in combination with chloroquine for 7 d. Immunofluorescence (IF) staining for O. tsutsugamushi was performed 4 hr and 7 d after inoculation of the bacteria, and IF-positive foci were enumerated.

RESULTS

Chloroquine inhibited the growth of O. tsutsugamushi by 15.5%. In combination with chloroquine, the antimicrobial effects increased by 4.4% for doxycycline (a 92.9% reduction of bacterial numbers for doxycycline versus a 97.3% reduction for doxycycline plus chloroquine), 4.6% for rifampin (90.0% versus 94.6%), and 8.3% for azithromycin (86.9% versus 95.2%). The antimicrobial effect of the antibiotics alone was significantly different compared to the combined effect of antibiotics and chloroquine (Wilcoxon signed-rank test, P = 0.001).

CONCLUSIONS

The combined use of chloroquine with an antibiotic for the treatment of O. tsutsugamushi infections may be useful for increasing the efficacy of the antibiotics.

Single dosage of doxycycline for prophylaxis against leptospiral infection and leptospirosis during urban flooding in southern Thailand: a non-randomized controlled trial

This study was conducted to investigate the protective efficacy of a single dosage of 200 mg doxycycline against leptospiral infection and leptospirosis and associated risk factors among residents exposed to flooding in southern Thailand. Of 641 participants, 600 received doxycycline while 41 did not. Twenty two participants were infected with Leptospira and six developed leptospirosis. Having a laceration wound was significantly associated with leptospiral infection (odds ratio [OR] = 37.20; P < 0.001) and leptospirosis (OR = 18.24; P = 0.003) whereas exposure to flood more than 3 h per day was associated with only leptospiral infection (OR = 3.70; P = 0.038). Seventeen participants who received doxycycline and five who did not, were infected with Leptospira, resulting a protective efficacy of 76.8% (95% confidence interval [CI] = 34.3%-92.0%). Four who received doxycycline and two who did not, developed leptospirosis, resulting a protective efficacy of 86.3% (CI = -9.8%-98.2%). Among the participants with laceration wound, the protective efficacy for leptospiral infection was 92.0% (CI = 81.2%-96.6%) and for leptospirosis was 95.6% (CI = 78.2%-99.3%). Among the participants exposed to flood water less than or equal to 3 h per day, the protective efficacy for leptospiral infection was 89.2% (95% CI 63.6%-96.67%). A single dosage of 200 mg doxycycline for prophylaxis might be effective for preventing leptospirosis among flood victims with laceration wound after recent flood exposure.

Salvianolic acid A, a matrix metalloproteinase-9 inhibitor of Salvia miltiorrhiza, attenuates aortic aneurysm formation in apolipoprotein E-deficient mice

Aortic aneurysm (AA) is a life-threatening vascular disease in defect of effective pharmaceutical therapy. Matrix metalloproteinase-9 (MMP-9) is implicated in the development of chronic vascular diseases including aneurysm, but the effective MMP-9 inhibitors are far from development. To develop new candidate for AA therapy, we evaluated the efficiency of salvianolic acid A (SalA), a novel MMP-9 inhibitor, on AA progression in a mouse model and characterized the mechanism of action. SalA is a water soluble compound of the herbal drug Rhizoma Salviae miltiorrhizae (Danshen) which in China is widely used for the treatment of hypertension, coronary artery diseases and myocardial infarction. MMPs activity was evaluated by enzyme kinetic analysis in vitro and in-gel gelatin zymography in vivo. SalA showed selectivity on gelatinase (MMP-2 and MMP-9) than on collagenase (MMP-8 and MMP-13) in vitro, and specificity on MMP-9 than MMP-2 in vivo. Aortic aneurysm was induced by angiotension II (AngII) in apolipoprotein E-deficient (ApoE(-/-)) mice. Aortic structure was evaluated by hematoxylin and eosin, picrosirius red, orein stain. Macrophage infiltration was detected by immunohistochemistry in vivo and transwell in vitro. Comparing with doxycycline (Dox), a well-known MMPs inhibitor, SalA showed similar efficiency against AA progression. SalA significantly decreased aortic diameter and aneurysm severity, ameliorated integrity of vascular structure, inhibited elastin fragmentation and macrophage infiltration. Furthermore, SalA showed greater safety than Dox based on hepatotoxicity evaluation. Our results demonstrated that SalA held great potential for AA therapy.

What happens when we routinely give doxycycline to medical abortion patients?

OBJECTIVES

Routine provision of antibiotics following medical abortion is common yet practitioners and professional societies differ on its utility. Our study compares the side effects experienced by women who were prescribed doxycycline following medical abortion to those who were not and assesses the adherence to one prescribed regimen.

STUDY DESIGN

This was a prospective, observational, open-label study from a convenience sample. Women seeking medical abortion were enrolled in nine study sites, including four clinics that routinely prescribe a seven-day course of doxycycline (Doxycycline arm) and five clinics that do not routinely prescribe any antibiotics (No Doxycycline arm). Seven to fourteen days following the administration of mifepristone, women were asked to self-administer a computer-based survey. The survey asked about side effects experienced (both arms) and adherence to the regimen (Doxycycline arm only).

RESULTS

Five hundred eighty-one women were enrolled (278 in the Doxycycline arm and 303 in the No Doxycycline arm). There was a trend toward increased nausea in the Doxycycline arm (47.8% vs. 40.9%; p=.056) and a statistically significant difference in vomiting (25.2% vs. 18.5%; p=.032). Almost all women in the Doxycycline arm reported taking at least one pill, however only 28.3% reported "perfect adherence." The most common reasons reported for taking fewer pills than instructed were that participants were still taking them (beyond 7 days) or that they forgot to take them.

CONCLUSION

Women who were prescribed doxycycline following medical abortion reported moderate adherence and experienced significantly more vomiting than their counterparts.

IMPLICATIONS

In the absence of robust evidence that prescribing 7 days of doxycycline following medical abortion is effective at reducing serious infections, these data can assist the public health community with deciding whether routine provision is the most appropriate strategy.

Experimental Dirofilaria immitis infection in dogs: effects of doxycycline and Advantage Multi® administration on immature adult parasites

To better understand the efficacy of doxycycline and 10% imidacloprid+2.5% moxidectin (Advantage Multi(®); Bayer Animal Health, Shawnee Mission, Kansas) on immature adult Dirofilaria immitis parasites and the results of antigen tests, 12 healthy, randomly selected dogs were experimentally infected with D. immitis and monitored for 407 days. Two dogs in each of three subgroups of four dogs were each infected with six (total of 6 dogs) or 12 (total of 6 dogs) D. immitis infective third-stage larvae (L3) obtained from infected mosquitoes. Doxycycline (10mg/kg per os twice daily×30 days) and 10% imidacloprid+2.5% moxidectin (1ml/kg by topical application every 30 days) treatment was initiated at 105 (Group A) and 149 (Group B) days post infection (PI) in two groups. One subgroup of two dogs given 6 L3 and one subgroup of two dogs given 12 L3 remained as untreated controls (GroupC). Serum obtained regularly throughout the study was evaluated by ELISA (PetChek(®) Heartworm-PF Antigen Test, IDEXX Laboratories, Inc.) for D. immitis adult circulating antigens. Six of the eight dogs in the treated groups had detectable antigenemia starting between 148 and 240 days post infection, but antigen was not detected in any treated dog at the end of the study. In the control subgroups, the dogs that received 6 L3 had no detectable antigen while the two dogs that received 12 L3 had detectable antigen beginning on Day 180 that persisted until the end of the study. None of the infected dogs had evidence of circulating microfilariae. At necropsy, no heartworms were recovered from the treated dogs, but all dogs in the untreated group had viable adult heartworms. These results indicate that early immature adult worms (3.5 and 5 months of age) of D. immitis were susceptible to a combined treatment regimen of doxycycline and 10% imidacloprid+2.5% moxidectin.

Antibody/doxycycline combined therapy for pulmonary ricinosis: Attenuation of inflammation improves survival of ricin-intoxicated mice

Ricin, a highly toxic plant-derived toxin, is considered a potential weapon in biological warfare due to its high availability and ease of preparation. Pulmonary exposure to ricin results in the generation of an acute edematous inflammation followed by respiratory insufficiency and death. Passive immunization with polyclonal anti-ricin antibodies conferred protection against pulmonary ricinosis, however, at clinically-relevant time points for treatment, survival rates were limited. In this study, intranasal instillation of a lethal dose of ricin to mice, served as a lung challenge model for the evaluation and comparison of different therapeutic modalities against pulmonary ricinosis. We show that treatment with doxycycline resulted in a significant reduction of pro-inflammatory cytokines, markers of oxidative stress and capillary permeability in the lungs of the mice. Moreover, survival rates of mice intoxicated with ricin and treated 24 h later with anti-ricin antibody were significantly improved by co-administration of doxycycline. In contrast, co-administration of the steroid drug dexamethasone with anti-ricin antibodies did not increase survival rates when administered at late hours after intoxication, however dexamethasone did exert a positive effect on survival when applied in conjunction with the doxycycline treatment. These studies strongly suggest that combined therapy, comprised of neutralizing anti-ricin antibodies and an appropriate anti-inflammatory agent, can promote high-level protection against pulmonary ricinosis at clinically-relevant time points post-exposure.

Stability of antibacterial activity of Chlorhexidine and Doxycycline in bovine root dentine

OBJECTIVE

The aim of this study was to compare the substantivity of chlorhexidine (CHX) and doxycycline bond to the dentin in diffusion disk method.

METHODS

A total of 92 dentin disks were prepared from Bovine's teeth root. After removing cementum and standardizing disks in weight and outer diameter, they were irrigated with sodium hypochlorite 2.5%, ethylenediaminetetraacetic acid 17% and sterile saline and sterilled in autoclave. Then, the first group (n = 36) were irrigated with chlrohexine 2% and the second group (n = 36) with doxycycline 100 mg/mL, each for a period of 10 min. The third group (n = 20) was considered as the control group. Samples were divided into four subgroups, which after 1 day, 3, 6, and 12 weeks were incubated in plates containing Muller Hinton agar broth and Enterococcus faecalis for a period of 48 h at 37°C temperature; then the diameter of the zone of inhibition was measured. The antimicrobial effect of irrigating solutions without binding to the dentin was also studied using the plate well method. One-way and univariate variance tests as well as Post-hoc Tukey were used for data analyses.

FINDINGS

The diameter of the zone of inhibition of doxycycline group was significantly more than the CHX group from the beginning to the 3(rd) week (P < 0.005). After 3(rd) week, mean diameter in doxycycline group declined as compared with the CHX group up to 12(th) week (P < 0.005). The difference between means in two groups was not significant in the 3(rd) week (P = 0.87).

CONCLUSION

The results of this study show that CHX and doxycycline show antibacterial activity for 12 weeks; although after 3(rd) week, the substantivity of CHX was significantly greater than doxycycline. Both of these irrigants can be used in other pharmacological and medical fields whenever a long-lasting antibacterial action is needed.

Clinical assessment of post-adulticide complications in Dirofilaria immitis-naturally infected dogs treated with doxycycline and ivermectin

This study shows that a combination of doxycycline (10mg/kg/sid for 30 days) and ivermectin (6 μg/kg/every 15 days for 6 months) is well tolerated for the treatment of canine heartworm disease (HWD). Monthly echocardiography showed that 84% of treated dogs either progressively improved parameters indicative of pulmonary hypertension or, following slight worsening, resolved all signs. Thoracic radiography showed the persistence of interstitial inflammation, even though also in this case, approximately 70% of the dogs steadily improved or worsened but then improved by the end of the study.

Metalloproteinase inhibition prevents inhibitory synapse reorganization and seizure genesis

The integrity and stability of interneurons in a cortical network are essential for proper network function. Loss of interneuron synaptic stability and precise organization can lead to disruptions in the excitation/inhibition balance, a characteristic of epilepsy. This study aimed to identify alterations to the GABAergic interneuron network in the piriform cortex (PC: a cortical area believed to be involved in the development of seizures) after kindling-induced seizures. Immunohistochemistry was used to mark perineuronal nets (PNNs: structures in the extracellular matrix that provide synaptic stability and restrict reorganization of inhibitory interneurons) and interneuron nerve terminals in control and kindled tissues. We found that PNNs were significantly decreased around parvalbumin-positive interneurons after the induction of experimental epilepsy. Additionally, we found layer-specific increases in GABA release sites originating from calbindin, calretinin, and parvalbumin interneurons, implying that there is a re-wiring of the interneuronal network. This increase in release sites was matched by an increase in GABAergic post-synaptic densities. We hypothesized that the breakdown of the PNN could be due to the activity of matrix metalloproteinases (MMP) and that the prevention of PNN breakdown may reduce the rewiring of interneuronal circuits and suppress seizures. To test this hypothesis we employed doxycycline, a broad spectrum MMP inhibitor, to stabilize PNNs in kindled rats. We found that doxycycline prevented PNN breakdown, re-organization of the inhibitory innervation, and seizure genesis. Our observations indicate that PNN degradation may be necessary for the development of seizures by facilitating interneuron plasticity and increased GABAergic activity.

Effects of topical intranasal doxycycline treatment in the rat allergic rhinitis model

Objectives

Allergic rhinitis (AR) is a chronic upper respiratory tract disease that inflames the mucous membranes of the nose and occurs when circulating inflammatory cells including eosinophils and basophils migrate to and accumulate in the inflammation area by passing through the interstitium and capillary walls. To pass through these barriers, the inflammatory cells degrade extracellular matrix proteins. Matrix metalloproteinases (MMPs) released by inflammatory cells mediate the degradation of these proteins. MMPs have synthetic inhibitors and doxycycline, a tetracycline antibiotic, inhibits MMPs. This study investigated the efficiency of intranasal doxycycline in decreasing the symptoms and inflammatory cell infiltration in an animal model of AR.

Methods

AR was created in female Wistar rats by repeated intranasal challenge with ovalbumin by intraperitoneal injection. For 15 days, topical intranasal doxycycline was administered one hour before ovalbumin administration. Following intranasal administration, nasal symptoms were scored and the nasal mucosae of all rats were evaluated histopathologically. To investigate tissue changes, hematoxyline-eosin and Alcian blue/periodic acid Schiff stains were used. As well, cilia loss, goblet cell changes, vascular congestion, vascular proliferation, inflammatory cell infiltration, eosinophil infiltration and the degree of hypertrophy in chondrocytes were evaluated with light microscopy.

Results

Typical symptoms of AR were decreased by intranasal doxycycline administration. These effects were stable after repeated intranasal ovalbumin administration. Histological evaluation of doxycycline treated rats did not reveal typical inflammatory changes associated with AR.

Conclusion

MMPs may have crucial functions in AR and topical intranasal doxycycline, which decreases inflammatory cell infiltration, may offer an alternative therapy for AR.

In situ forming implants for periodontitis treatment with improved adhesive properties

Novel in situ forming implants are presented showing a promising potential to overcome one of the major practical hurdles associated with local periodontitis treatment: limited adhesion to the surrounding tissue, resulting in accidental expulsion of at least parts of the implants from the patients' pockets. This leads to high uncertainties in the systems' residence times at the site of action and in the resulting drug exposure. In the present study, the addition of different types and amounts of plasticizers (acetyltributyl citrate and dibutyl sebacate) as well as of adhesive polymers (e.g., cellulose derivatives such as hydroxypropyl methylcellulose) is shown to allow for a significant increase in the stickiness of poly(lactic-co-glycolic acid)-based implants. The systems are formed in situ from N-methyl pyrrolidone-based liquid formulations. Importantly, at the same time, good plastic deformability of the implants can be provided and desired drug release patterns can be fine-tuned using several formulation tools. The antimicrobial activity of this new type of in situ forming implants, loaded with doxycycline hyclate, was demonstrated using the agar well diffusion method and multiple Streptococcus strains isolated from the oral microflora of patients suffering from periodontitis.

A highly sensitive and selective assay of doxycycline by dualwavelength overlapping resonance Rayleigh scattering

A dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was developed and validated for highly sensitive and selective assay of doxycycline residues in several meat samples. The response signals were dependent on the specific multi-site coordination between lanthanum(III) and doxycycline (DOTC). And La(III)-DOTC complex would further aggregate to form [La(III)-DOTC]n nanoparticles, resulting in the occurrence of two new scattering peaks. Notably, with the addition of DOTC, the increments of both of these two wavelengths were proportional to the concentration of DOTC over the ranges of 3.9-4.0×10(3) nmol L(-1) (1.7-1.8×10(3) μg/kg). The detection limit of DWO-RRS was 1.1 nmol L(-1) (0.5 μg/kg), which was lower than or comparable to most of the published methods. Additionally, the generating mechanisms of multi-response RRS signals were discussed and a semi-empirical principle was established for better design of multi-response RRS probes.

Structural and thermodynamic characterization of doxycycline/β-cyclodextrin supramolecular complex and its bacterial membrane interactions

Doxycycline is a semi-synthetic antibiotic commonly used for the treatment of many aerobic and anaerobic bacteria. It inhibits the activity of matrix metalloproteinases (MMPs) and affects cell proliferation. In this study, the structural and thermodynamic parameters of free DOX and a DOX/βCD complex were investigated, as well as their interactions and effects on Staphylococcus aureus cells and cellular cytotoxicity. Complexation of DOX and βCD was confirmed to be an enthalpy- and entropy-driven process, and a low equilibrium constant was obtained. Treatment of S. aureus with higher concentrations of DOX or DOX/βCD resulted in an exponential decrease in S. aureus cell size, as well as a gradual neutralization of zeta potential. These thermodynamic profiles suggest that ion-pairing and hydrogen bonding interactions occur between DOX and the membrane of S. aureus. In addition, the adhesion of βCD to the cell membrane via hydrogen bonding is hypothesized to mediate a synergistic effect which accounts for the higher activity of DOX/βCD against S. aureus compared to pure DOX. Lower cytotoxicity and induction of osteoblast proliferation was also associated with DOX/βCD compared with free DOX. These promising findings demonstrate the potential for DOX/βCD to mediate antimicrobial activity at lower concentrations, and provides a strategy for the development of other antimicrobial formulations.

Development of a doxycycline-inducible lentiviral plasmid with an instant regulatory feature

Lentiviruses provide highly efficient gene delivery vehicles in both dividing and non-dividing cells. Inducible gene expression systems often employ a specific cell line that constitutively expresses a regulatory protein for transgene expression. As one of such inducible expression systems the Tet-On system uses a cell line expressing reverse tetracycline-responsive transcriptional activator (rtTA). The rtTA protein binds to the tetracycline-responsive element (TRE) in the promoter and activates transcription of a transgene in a doxycycline-dependent manner. To establish a universal and instant regulatory system without generating Tet-On cell lines, the cDNAs of rtTA and a testing target gene (PPM1B) were cloned in the bi-directional TRE-containing promoters. Here, we examined whether a basal leaky expression of rtTA allows instantly inducible expression of both rtTA itself and the target gene, PPM1B in a single plasmid using the two mini-CMV promoters. Transient transfection of the lentiviral plasmids into human embryonic kidney HEK293T cells showed a significant induction of PPM1B expression in response to doxycycline, suggesting that these lentiviral plasmids can be used as an instantly inducible mammalian expression vector. However, the expression of rtTA by lentiviral transduction shows a minimal expression without a consistent response to doxycycline, suggesting that the utility of these lentiviral vectors is limited. A potential solution to overcome lentiviral transgene inactivation is proposed.

[Lyme disease acrodermitis chronica atrophicans: misleading vascular signs]

Lyme disease acrodermatitis chronica atrophicans is a tertiary form of Lyme borrelliosis. It occurs at least six months, but also up to several years, after a tick bite. This rare condition is probably underestimated because of the difficult diagnosis. Clinical presentations of acrodermatitis chronic atrophicans are quite variable depending upon the duration of the disease. Complimentary explorations are difficult to interpret and rarely specific. Only rare configurations allow formal diagnosis of Borrelia burgdoferi infection. We present a patient who exhibited an atypical clinical presentation of Lyme disease acrodermatitis chronic atrophicans. The clinical outcome was quite favorable with treatment, confirming the diagnosis. Such treatments, which are well tolerated and highly effective, are essential since an untreated disease can lead to potentially severe neurological involvement.

Where are we with Wolbachia and doxycycline: an in-depth review of the current state of our knowledge

Dirofilaria immitis, the cause of canine and feline heartworm disease, was the first filarial nematode described to harbour the bacterial endosymbiont Wolbachia. This ground-breaking discovery has led to intense research aimed at unravelling the nature of the endosymbiotic relationship; genomic studies have revealed how the bacteria may interact with the parasite and help explain why each is so dependent on the other. Analysis of the immune response to these bacteria may elucidate the mechanisms through which filarial parasites are able to survive for long periods of time in otherwise immune-competent hosts. Finally, studies aimed at the removal of the bacteria using specific antibiotic treatment in infected hosts is leading to the development of novel approaches for interrupting the transmission cycle and for the treatment and control of heartworm disease.

Slc26a4-insufficiency causes fluctuating hearing loss and stria vascularis dysfunction

SLC26A4 mutations can cause a distinctive hearing loss phenotype with sudden drops and fluctuation in patients. Existing Slc26a4 mutant mouse lines have a profound loss of hearing and vestibular function, with severe inner ear malformations that do not model this human phenotype. In this study, we generated Slc26a4-insufficient mice by manipulation of doxycycline administration to a transgenic mouse line in which all Slc26a4 expression was under the control of doxycycline. Doxycycline was administered from conception to embryonic day 17.5, and then it was discontinued. Auditory brainstem response thresholds showed significant fluctuation of hearing loss from 1 through 3months of age. The endocochlear potential, which is required for inner ear sensory cell function, correlated with auditory brainstem response thresholds. We observed degeneration of stria vascularis intermediate cells, the cells that generate the endocochlear potential, but no other abnormalities within the cochlea. We conclude that fluctuations of hearing result from fluctuations of the endocochlear potential and stria vascularis dysfunction in Slc26a4-insufficient mouse ears. This model can now be used to test potential interventions to reduce or prevent sudden hearing loss or fluctuation in human patients. Our strategy to generate a hypomorphic mouse model utilizing the tet-on system will be applicable to other diseases in which a hypomorphic allele is needed to model the human phenotype.

Effects of doxycycline on cx43 distribution and cardiac arrhythmia susceptibility of rats after myocardial infarction

This study aims to observe the effects of doxycycline (DOX) on gap junction remodeling after MI and the susceptibility of rats to cardiac arrhythmia. The proximal left anterior descending coronary artery of rats was ligated to establish a myocardial infarction animal model. DOX, methylprednisolone (MP), or vehicle was intraperitoneally injected into the animals for two weeks. Then, the heart size and heart function of all animals were determined through echocardiography. The experimental animals were sacrificed after the electrophysiologic study. Myocardial tissues were sampled to analyze the distribution of Cx43 using immunofluorescence; the Cx43 content was analyzed using western blot analysis; and the MMP-2 and MMP-9 activity in the myocardium was analyzed using gelatin zymography. The distribution of Cx43 in the border of the infarcted myocardia in the MI and MP groups was clearly disrupted and the Cx43 content was significantly reduced. In addition, the distribution of Cx43 in the border of the infarct in the DOX group was relatively regular, whereas two weeks of DOX treatment significantly inhibited MMP activity. Meanwhile, the induction rate of arrhythmia in the rats after DOX treatment was lower than those in the MI and MP groups. The results show that DOX treatment after myocardial infarction improves gap junction remodeling in the myocardial tissue near the infarcted area by inhibiting MMP activity and reducing susceptibility to cardiac arrhythmia.

Bioactive implant surface with electrochemically bound doxycycline promotes bone formation markers in vitro and in vivo

OBJECTIVES

The objective of this study was to demonstrate a successful binding of Doxy hyclate onto a titanium zirconium alloy surface.

METHODS

The coating was done on titanium zirconium coins in a cathodic polarization setup. The surface binding was analyzed by SEM, SIMS, UV-vis, FTIR and XPS. The in vitro biological response was tested with MC3T3-E1 murine pre-osteoblast cells after 14 days of cultivation and analyzed in RT-PCR. A rabbit tibial model was also used to confirm its bioactivity in vivo after 4 and 8 weeks healing by means of microCT.

RESULTS

A mean of 141 μg/cm(2) of Doxy was found firmly attached and undamaged on the coin. Inclusion of Doxy was documented up to a depth of approximately 0.44 μm by tracing the (12)C carbon isotope. The bioactivity of the coating was documented by an in vitro study with murine osteoblasts, which showed significantly increased alkaline phosphatase and osteocalcin gene expression levels after 14 days of cell culture along with low cytotoxicity. Doxy coated surfaces showed increased bone formation markers at 8 weeks of healing in a rabbit tibial model.

SIGNIFICANCE

The present work demonstrates a method of binding the broad spectrum antibiotic doxycycline (Doxy) to an implant surface to improve bone formation and reduce the risk of infection around the implant. We have demonstrated that TiZr implants with electrochemically bound Doxy promote bone formation markers in vitro and in vivo.

Doxycycline induced generalized bullous fixed drug eruption - A case report

Adverse drug reactions are a major hazard of modern medicine. Fixed drug eruption, which is a cutaneous adverse drug reaction, is commonly seen with antimicrobials and analgesics. Here we report 37-year-old female with bullous fixed drug eruptions due to doxycycline administration.

Reduction in infection-related mortality since modifications in the regimen of medical abortion

BACKGROUND

From 2001 to March 2006 Planned Parenthood health centers throughout the United States provided medical abortion by a regimen of oral mifepristone followed 24-48 h later by vaginal misoprostol. In response to concerns about serious infections, in early 2006 Planned Parenthood changed the route of misoprostol administration to buccal and required either routine antibiotic coverage or universal screening and treatment for chlamydia; in July 2007, Planned Parenthood began requiring routine antibiotic coverage for all medical abortions.

METHODS

We performed a retrospective analysis of Planned Parenthood cases assessing the rates of mortality caused by infection following medical abortion during a time period when misoprostol was administered vaginally (2001 through March 2006), as compared with the rate from April 2006 to the end of 2012 after a change to buccal administration of misoprostol and after initiation of new infection-reduction strategies.

RESULTS

The mortality rate dropped significantly in the 81-month period after the joint change to (1) buccal misoprostol replacing vaginal misoprostol and (2) either sexually transmitted infection (STI) screening or routine preventative antibiotic coverage (15 month period) or universal routine preventative antibiotic coverage as part of the medical abortion (66-month period), from 1.37/100,000 to 0.00/100,000, P=.013 (difference=1.37/100,000, 95% CI 0.47-4.03 per 100,000).

CONCLUSION

The infection-caused mortality rate following medical abortion declined by 100% following a change from vaginal to buccal administration of misoprostol combined with screen-and-treat or, far more commonly, routine antibiotic coverage.

SIGNIFICANCE

Deaths from infection following medical abortion declined to zero after a change in the regimen.

First Case of Bartonella henselae Bacteremia in Korea

Bartonella henselae causes cat-scratch disease, bacteremia, and various focal infections. Despite the worldwide occurrence of B. henselae infections, reports in humans are rare in Korea. The clinical manifestation of all 5 previously reported cases was lymphadenopathy. Herein, we report a case of bacteremia in a woman who presented with prolonged fever. B. henselae was isolated from a blood specimen by cell culture. Conventional polymerase chain reaction amplification and sequencing of the 16S-23S rRNA intergenic space region confirmed the isolate to be B. henselae. The patient had no underlying immunocompromising conditions and no recent exposure to animals. She was successfully managed with a combination of doxycycline and hydroxychloroquine.

Overlap of Doxycycline Fluorescence with that of the Redox-Sensitive Intracellular Reporter roGFP

Tetracycline-inducible systems allow for either suppression or induction of transgene expression to facilitate studies of cell physiology. Doxycycline is a preferred inducer for these gene expression systems due to its membrane permeability; however, the heterocyclic structure of doxycycline exhibits fluorogenic properties that can potentially bias measurement of other fluorochromes. Thus the simultaneous use of tetracycline-inducible systems and fluorescent proteins as reporter genes or as intracellular biosensors may lead to potentially confounding results. Herein, using cells which co-express the ratiometric redox sensitive intracellular reporter, roGFP, and a tetracycline-inducible reporter plasmid encoding the reporter gene, mCherry, as a model system, we describe the overlapping intracellular fluorescent signals between doxycycline and commonly used intracellular fluorescent probes. In our cells, the addition of doxycycline to cells caused a dose- and time-dependent increase in cell fluorescence with 405 nm excitation which overlapped with that of the oxidized configuration of roGFP. Incubating cells in concentrations of doxycycline less than 1 μg/mL and removing doxycycline from the media 60 min before performing experiments eliminated fluorescence interference while still maintaining maximal reporter transgene activation.

Tetracyclines cause cell stress-dependent ATF4 activation and mTOR inhibition

Tetracyclines have long been used as valuable broad-spectrum antibiotics. The high antibacterial activity of tetracyclines, combined with their good tolerability, has led to their widespread use in treating various infectious diseases. However, similar to other antibiotics, tetracyclines are also known for their adverse effects on different human tissues, including hepatic steatosis. We observed that tetracyclines, including doxycycline and minocycline, caused enhanced expression of the liver chalone inhibin βE in HepG2 cells, mediated by the cell stress-regulated transcription factor ATF4. ATF4 and its target genes ATF3, CHOP, and inhibin βE are involved in cell cycle control, cell survival, cell metabolism, and modulation of cytokine expression. Furthermore, we observed that long term tetracycline incubation also caused inhibition of the mTOR complex, a central regulator of cell metabolism, further contributing to the observed cell-cycle arrest and autophagy in doxycycline- and minocycline-treated cell lines. ATF4 activation and mTOR inhibition link two crucial regulators of the cellular stress response and cell metabolism to the effects of tetracyclines on eukaryotic cell metabolism, and may help to understand the antibiotic-independent influence of these drugs on human tissues. Since the observed effects of tetracyclines on human cells were also found to be dependent on the magnesium ion concentrations supplied, the data further indicate the importance of magnesium supplementation to reduce or prevent side effects of long term treatment with tetracyclines.

Role of matrix metalloproteinases (MMPs) and MMP inhibitors on intracranial aneurysms: a review article

Cerebrovascular disease is one of the leading causes of death in the world, and about one-fourth of cerebrovasculardeaths are due to ruptured cerebral aneurysms (CA). Hence it is important to find a way to reduce aneurysmformation and its subsequent morbidity and mortality. Proteolytic activity capable of lysing gelatin hasbeen shown to be increased in aneurysm tissue and expression of plasmin, membrane-type matrix metalloproteinase-1(MT1-MMP), and matrix metalloproteinase-2 (MMP-2) in aneurysmal wall is more than what we observein normal cerebral arteries. MMP inhibitors such as doxycycline and statins may prohibit aneurysm formationand growth. MMPs are important in tissue remodeling associated with various physiological and pathologicalprocesses such as morphogenesis, angiogenesis, apoptosis and tissue repair. In this article we review therole of MMPs and MMP inhibitors in formation of aneurysm.

Doxycycline-regulated GDNF expression promotes axonal regeneration and functional recovery in transected peripheral nerve

Increased production of neurotrophic factors (NTFs) is one of the key responses seen following peripheral nerve injury, making them an attractive choice for pro-regenerative gene therapies. However, the downside of over-expression of certain NTFs, including glial cell line-derived neurotrophic factor (GDNF), was earlier found to be the trapping and misdirection of regenerating axons, the so-called 'candy-store' effect. We report a proof-of-principle study on the application of conditional GDNF expression system in injured peripheral nerve. We engineered Schwann cells (SCs) using dendrimers or lentiviral transduction with the vector providing doxycycline-regulated GDNF expression. Injection of GDNF-modified cells into the injured peripheral nerve followed by time-restricted administration of doxycycline demonstrated that GDNF expression in SCs can also be controlled locally in the peripheral nerves of the experimental animals. Cell-based GDNF therapy was shown to increase the extent of axonal regeneration, while controlled deactivation of GDNF effectively prevented trapping of regenerating axons in GDNF-enriched areas, and was associated with improved functional recovery.

Doxycycline poly e-caprolactone nanofibers in patients with chronic periodontitis - a clinical evaluation

AIM

To develop a low-dose controlled-release delivery system for the treatment of periodontal infections. A new sustained release drug system of Poly e-caprolactone (PCL) nanofibers containing doxycycline (DOX) was successfully electrospun and evaluated clinically for periodontal diseases. The retentive doxycycline nanofibres were shown to provide a controlled delivery of the drug.

MATERIAL AND METHODS

Nanofibers were prepared with DOX in PCL by electrospinning technique. The drug-coated nanofibres provided sustained effect up to a period of 11 days (264 h) and followed first order release. Forty sites in 7 patients (4 females and 3 males) with chronic periodontitis (5-8mm probing depth) were allocated in 2 experimental treatment groups, Group A-SRP (Scaling and Root Planing) + DOX nanofibers and Group B -SRP (Scaling and Root Planing) alone (control group). All these patients were evaluated clinically for probing depth (PD), plaque index (PI) and gingival index (GI).

RESULTS

Both the treatment groups were found to be efficacious in the treatment of periodontal disease as demonstrated by improvement in PD, PI and GI.

CONCLUSION

Combination of SRP (Scaling and Root Planing) + DOX nanofibers (Group A) resulted in added benefits compared to the control group.

Effects of doxycycline on depressive-like behavior in mice after lipopolysaccharide (LPS) administration

Current evidences support inflammation, oxidative and nitrogen stress, as well as brain-derived neurotrophic factor (BDNF) signaling mechanisms as important in depression pathophysiology. Tetracycline antibiotics have anti-inflammatory and antioxidant properties. Preliminary evidence indicates that minocycline has antidepressant properties. Doxycycline (DOXY) has favorable pharmacokinetic and safety profiles when compared to other tetracycline congeners. The antidepressant activity of DOXY has not been adequately investigated. This study evaluated the effects of DOXY (25 and 50 mg/kg, i.p.) on LPS-induced (0.5 mg/kg, i.p.) depressive-like behavior. Doxycycline was administered 30 min before LPS (pre-LPS) or 1.5 and 23.5 h following LPS (post-LPS) administration in mice. LPS-treated animals presented an increase in immobility time in the forced swimming test (FST) when compared to controls 24 h after endotoxin administration. Similarly to imipramine (IMI-10 mg/kg, i.p.), DOXY at both doses prevented and reversed LPS-induced alterations in the FST. IL-1β content was increased 24 h after LPS administration in striatum, hippocampus and prefrontal cortex. IMI and DOXY prevented and reversed LPS-induced increase in IL-1β. IMI and DOXY also prevented and reversed LPS-induced alterations in nitrite content and oxidative stress parameters (lipid peroxidation and reduced glutathione levels). Both DOXY and IMI prevented LPS-induced decrease in hippocampal BDNF levels. Taken together, our results demonstrate that DOXY is comparable to IMI in effectively ameliorate LPS-induced depressive-like behavior, providing a rationale for testing DOXY's antidepressant efficacy in humans.

Minocycline, often forgotten but preferred to trimethoprim-sulfamethoxazole or doxycycline for the treatment of community-acquired meticillin-resistant Staphylococcus aureus skin and soft-tissue infections

Treatment of uncomplicated skin and soft-tissue abscesses caused by meticillin-sensitive Staphylococcus aureus or meticillin-resistant S. aureus (MRSA) is problematic. Incision and drainage aside, oral antibiotic therapy for uncomplicated community-acquired MRSA (CA-MRSA) is limited and frequent choices include clindamycin, doxycycline or trimethoprim-sulfamethoxazole (TMP-SMX). The most common oral antibiotics used for CA-MRSA are doxycycline or TMP-SMX, which often fail to eradicate the infection. With MRSA, in vitro susceptibilities do not always predict in vivo effectiveness. In situations where doxycycline or TMP-SMX fails in the treatment of uncomplicated cutaneous abscesses due to CA-MRSA, minocycline is reliably effective.

Minocycline and doxycycline, but not other tetracycline-derived compounds, protect liver cells from chemical hypoxia and ischemia/reperfusion injury by inhibition of the mitochondrial calcium uniporter

Minocycline, a tetracycline-derived compound, mitigates damage caused by ischemia/reperfusion (I/R) injury. Here, 19 tetracycline-derived compounds were screened in comparison to minocycline for their ability to protect hepatocytes against damage from chemical hypoxia and I/R injury. Cultured rat hepatocytes were incubated with 50μM of each tetracycline-derived compound 20 min prior to exposure to 500μM iodoacetic acid plus 1mM KCN (chemical hypoxia). In other experiments, hepatocytes were incubated in anoxic Krebs-Ringer-HEPES buffer at pH6.2 for 4h prior to reoxygenation at pH7.4 (simulated I/R). Tetracycline-derived compounds were added 20 min prior to reperfusion. Ca(2+) uptake was measured in isolated rat liver mitochondria incubated with Fluo-5N. Cell killing after 120 min of chemical hypoxia measured by propidium iodide (PI) fluorometry was 87%, which decreased to 28% and 42% with minocycline and doxycycline, respectively. After I/R, cell killing at 120 min decreased from 79% with vehicle to 43% and 49% with minocycline and doxycycline. No other tested compound decreased killing. Minocycline and doxycycline also inhibited mitochondrial Ca(2+) uptake and suppressed the Ca(2+)-induced mitochondrial permeability transition (MPT), the penultimate cause of cell death in reperfusion injury. Ru360, a specific inhibitor of the mitochondrial calcium uniporter (MCU), also decreased cell killing after hypoxia and I/R and blocked mitochondrial Ca(2+) uptake and the MPT. Other proposed mechanisms, including mitochondrial depolarization and matrix metalloprotease inhibition, could not account for cytoprotection. Taken together, these results indicate that minocycline and doxycycline are cytoprotective by way of inhibition of MCU.

Relevance of microstructure for the early antibiotic release of fresh and pre-set calcium phosphate cements

Calcium phosphate cements (CPCs) have great potential as carriers for controlled release and vectoring of drugs in the skeletal system. However, a lot of work still has to be done in order to obtain reproducible and predictable release kinetics. A particular aspect that adds complexity to these materials is that they cannot be considered as stable matrices, since their microstructure evolves during the setting reaction. The aims of the present work were to analyze the effect of the microstructural evolution of the CPC during the setting reaction on the release kinetics of the antibiotic doxycycline hyclate and to assess the effect of the antibiotic on the microstructural development of the CPC. The incorporation of the drug in the CPC modified the textural and microstructural properties of the cements by acting as a nucleating agent for the heterogeneous precipitation of hydroxyapatite crystals, but did not affect its antibacterial activity. In vitro release experiments were carried out on readily prepared cements (fresh CPCs), and compared to those of pre-set CPCs. No burst release was found in any formulation. A marked difference in release kinetics was found at the initial stages; the evolving microstructure of fresh CPCs led to a two-step release. Initially, when the carrier was merely a suspension of α-TCP particles in water, a faster release was recorded, which rapidly evolved to a zero-order release. In contrast, pre-set CPCs released doxycycline following non-Fickian diffusion. The final release percentage was related to the total porosity and entrance pore size of each biomaterial.

[Update on SENLAT syndrome: scalp eschar and neck lymph adenopathy after a tick bite]

SENLAT syndrome, also known as TIBOLA/DEBONEL, is an emerging disease in France. The major symptoms are necrotic eschar on the scalp associated with painful cervical lymphadenopathy. It occurs mainly in women and children during the cold seasons after a bite by a Dermacentor tick, responsible for transmitting Rickettsia slovaca or Rickettsia raoultii. Cutaneous swabs are safe, easy and reliable tools that should be used routinely by physicians to confirm diagnosis. In this particular disease, they should be preferred to serology, which is less sensitive. Doxycycline is the antibiotic of choice for this syndrome.

Study of ehrlichiosis in kennel dogs under treatment and prevention during seven months in Dakar (Senegal)

In Dakar kennels where morbidity and mortality attributed to diseases transmitted by ticks were high, we conducted a field study to assess the prevalence of Ehrlichia canis, Anaplasma platys and Babesia spp. infections in two kennels (n = 34 dogs) and to study the impact of tick protection. The first day of the study, the E. canis PCR were positive in 18 dogs (53%). A. platys was found in one dog and all dogs were negative for Babesia spp. After one month of doxycycline treatment, the number of PCR positive dogs decreased significantly to 2 (5.9%). During seven months, all dogs were treated monthly topically with a novel combination (Certifect(®), Merial) delivering at least 6.7 mg fipronil/kg body weight, 8.0mg amitraz/kg and 6 mg (S)-methoprene/kg. The number of PCR positive dogs remained stable all over the seven months, with 4 dogs being positive at Day 90 and 2 at Day 210. The combination of treatment and monthly prevention had a significant effect in the two kennels. All dogs remained healthy, which was not the case in previous years.

Generation and characterization of a transgenic zebrafish expressing the reverse tetracycline transactivator

Conditional expression of a target gene during zebrafish development is a powerful approach to elucidate gene functions. The tetracycline-controlled systems have been successfully used in the modulation of gene expression in mammalian cells, but few lines of zebrafish carrying these systems are currently available. In this study, we had generated a stable transgenic zebrafish line that ubiquitously expressed the second-generation of reverse Tet transactivator (rtTA-M2). Southern blotting analysis and high-throughput genome sequencing verified that a single copy of rtTA-M2 gene had stably integrated into the zebrafish genome. After induction with doxycycline (Dox), a strong green fluorescent protein (GFP) was seen in rtTA-transgenic eggs injected with pTRE-EGFP plasmids. The fluorescent signal gradually decreased after the withdrawal of Dox and disappeared. However, leaky expression of GFP was undetectable before Dox-induction. Additionally, transgenic embryos expressing rtTA-M2 exhibited no obvious defects in morphological phenotypes, hatching behavior and expression patterns of developmental marker genes, suggesting that rtTA-M2 had little effect on the development of transgenic zebrafish. Moreover, expressed Dickkopf-1 (DKK1) in pTRE-DKK1-injected embryos led to alterations in the expression of marker genes associated with Wnt signaling. Thus, this rtTA-transgenic zebrafish can be utilized to dissect functions of genes in a temporal manner.

Scrub typhus

Scrub typhus is an acute febrile illness caused by orientia tsutsugamushi, transmitted to humans by the bite of the larva of trombiculid mites. It causes a disseminated vasculitic and perivascular inflammatory lesions resulting in significant vascular leakage and end-organ injury. It affects people of all ages and even though scrub typhus in pregnancy is uncommon, it is associated with increased foetal loss, preterm delivery, and small for gestational age infants. After an incubation period of 6-21 days, onset is characterized by fever, headache, myalgia, cough, and gastrointestinal symptoms. A primary papular lesion which later crusts to form a flat black eschar, may be present. If untreated, serious complications may occur involving various organs. Laboratory studies usually reveal leukopenia, thrombocytopenia, deranged hepatic and renal function, proteinuria and reticulonodular infiltrate. Owing to the potential for severe complications, diagnosis, and decision to initiate treatment should be based on clinical suspicion and confirmed by serologic tests. A therapeutic trial of tetracycline or chloramphenicol is indicated in patients in whom the diagnosis of scrub typhus is suspected. The recommended treatment regimen for scrub typhus is doxycycline. Alternative regimens include tetracycline, chloramphenicol, azithromycin, ciprofloxacin, rifampicin, and roxithromycin. Treatment of pregnant women with azithromycin was successfully done without relapse and with favorable pregnancy outcomes. Hence, early diagnosis and treatment are essential in order to reduce the mortality and the complications associated with the disease. We searched the English-language literature for reports of scrub typhus in children, pregnant women, and non-pregnant patients with scrub typhus, using the MEDLINE/PubMed database, which includes citations from 1945 to the present time. We used the search terms 'scrub typhus', 'scrub typhus' and 'pregnancy', 'scrub typhus' and 'children', 'scrub typhus' and 'complications', 'scrub typhus' and 'treatment'.

Doxycycline impacts hernia repair outcomes

BACKGROUND

Incisional hernias occur commonly in up to 20% of all abdominal operations. Incisional hernia formation has been associated with increased levels of matrix metalloproteinases (MMPs), reduced collagen 1, and increased collagen 3 expression. Doxycycline, a nonspecific inhibitor of MMPs, has been shown to beneficially reduce MMP levels in both cancer and aneurysm models. This study evaluates the impact of doxycycline upon MMP expression, collagen subtypes, and hernia repair distraction forces in an animal model of incisional hernia repair.

MATERIALS AND METHODS

Twenty-four Sprague Dawley rats underwent incisional hernia creation and subsequent repair with polypropylene mesh. Animals were administered doxycycline or saline daily beginning 1 d prior to hernia repair and survived for 1, 2, or 4 wk. Serum and tissue were evaluated for MMP content and collagen subtyping utilizing enzyme-linked immunosorbent assay and Western blot. Tensiometric properties of the native abdominal wall after hernia repair were measured with an Instron Corp. (Canton, MA) mechanical testing system.

RESULTS

There were no differences in control and experimental groups 1 and 2 wk following hernia repair; 4 wk following hernia repair, doxycycline treated animals demonstrated reduced serum MMP-2 and MMP-9 levels, reduced tissue levels of MMP-2, MMP-3, and MMP-9, and increased collagen 1 to 3 ratios. Distraction forces required to disrupt the hernia repair were increased in the doxycycline treated group compared with controls.

CONCLUSIONS

Doxycycline administration is associated with improved hernia repair strength with concomitant reduction of MMP levels with increased collagen 1 deposition. Longer term studies are required to better understand the impact of this treatment.

Lyme borreliosis and skin

Lyme disease is a multisystem illness which is caused by the strains of spirochete Borrelia burgdorferi sensu lato and transmitted by the tick, Ixodes. Though very commonly reported from the temperate regions of the world, the incidence has increased worldwide due to increasing travel and changing habitats of the vector. Few cases have been reported from the Indian subcontinent too. Skin manifestations are the earliest to occur, and diagnosing these lesions followed by appropriate treatment, can prevent complications of the disease, which are mainly neurological. The three main dermatological manifestations are erythema chronicum migrans, borrelial lymphocytoma and acrodermatitis chronica atrophicans. Many other dermatological conditions including morphea, lichen sclerosus and lately B cell lymphoma, have been attributed to the disease. Immunofluorescence and polymerase reaction tests have been developed to overcome the problems for diagnosis. Culture methods are also used for diagnosis. Treatment with Doxycycline is the mainstay of management, though prevention is of utmost importance. Vaccines against the condition are still not very successful. Hence, the importance of recognising the cutaneous manifestations early, to prevent systemic complications which can occur if left untreated, can be understood. This review highlights the cutaneous manifestations of Lyme borreliosis and its management.

Treatment of Dirofilaria repens microfilariaemia with a combination of doxycycline hyclate and ivermectin

Dirofilaria repens is one of the most widespread mosquito-borne filarioid responsible for infestations in dogs, usually characterized by nodules and other skin lesions. Additionally, the zoonotic potential of this nematode is of public health concern, given that D. repens has been often associated to human dirofilariosis in the Old World. In the present study, the therapeutic efficacy against D. repens microfilariae of a protocol based on doxycycline hyclate (Ronaxan(®), Merial), 10mg/kg every day for 30 days, and ivermectin (Cardotek 30(®), Merial), 6 μg/kg every 15 days for 6 months, was preliminarily investigated in two naturally infested dogs. Blood samples were collected every 30 days during 6 months of treatment and examined by a Knott's modified test and a duplex real-time PCR. The results here presented indicate that this therapeutic protocol, applied monthly, could be effective for treating microfilariaemia in dogs affected by subcutaneous dirofilariosis.

Doxycycline speeds up healing of chronic venous ulcers

Venous ulcers are common, with an overall prevalence of up to 2% in the general population of western countries, and have significant socioeconomic impact. Matrix metalloproteinases (MMPs) are involved in the alteration of extracellular matrix that could lead to venous ulceration. Sixty-four patients with venous ulcers were recruited in a 22-month period. All patients were subjected to the most appropriate treatment considering also the patient's wishes (compression therapy followed or not by vein surgery). Patients were randomised into two groups of 32 persons in each (groups A and B). Patients of group A in addition to the basic treatment, described above, received the administration of oral low doses of doxycycline 20 mg b.i.d. for 3 months, whereas patients of group B received basic treatment only. Healing was assessed by means of direct ulcer tracing with computerised planimetry. Group A showed a higher healing rate compared with group B. In group B, the lower healing rate was related to higher levels of MMP-9; neutrophil gelatinase-associated lipocalin and vascular endothelial growth factor, documented in plasma; wound fluid and biopsies executed and compared between both groups. Pharmacological treatments, as doxycycline administration, which by means of its immunomodulatory and anti-inflammatory actions, through the inhibition of MMP, could improve extracellular matrix functioning and represent a possible solution to support wound healing.

Evaluation of the effect of probiotic (inersan®) alone, combination of probiotic with doxycycline and doxycycline alone on aggressive periodontitis - a clinical and microbiological study

INTRODUCTION

The purpose of the present study was to evaluate the effect of a probiotic (Inersan®) alone, a combination of the probiotic with doxycycline and doxycycline alone on aggressive periodontitis patients.

METHODS

Thirty patients who satisfied the inclusion and exclusion criteria, were assigned to one of the above mentioned three groups by using block randomization. The clinical and the microbiological parameters were recorded on day 0, at 2 weeks and at 2 months. On day 0, before recording the clinical parameters, 0.5 ml of unstimulated saliva was collected for the evaluation of the microbiological parameters. The clinical parameters which were recorded were the plaque index, the gingival index, the probing pocket depth and the clinical attachment level. The microbiological parameters which were recorded were Lactobacilli and Aggregatibacter actinomycetemcomitans. After this, Scaling and Root Planing (SRP) was performed on day 0. Two weeks after the SRP, the patients were recalled for the saliva sample collection and for the evaluation of the clinical parameters. On the same day, medications were given to the patients to be taken for fourteen days according to the group which they belonged to (Group A - probiotic alone, Group B - a combination of the probiotic with doxycycline, Group C - doxycycline alone). The patients were then recalled at two months for the saliva sample collection and for the evaluation of the clinical parameters.

RESULTS

The administration of the probiotic alone, a combination of the probiotic with doxycycline and doxycycline alone, resulted in a decrease in the plaque index, the gingival index, the probing pocket depth and the clinical attachment level at 2 months, which was statistically significant (p < 0.05). The A. actinomycetemcomitans count tended to decrease in all the three groups at 2 months, which was statistically non-significant (p > 0.05). The Lactobacilli count tended to increase significantly in the probiotic alone group (p < 0.05).

CONCLUSION

Probiotics have a future in the treatment of aggressive periodontitis, as antibiotics are prescribed most of the time. These antibiotics can lead to the emergence of drug resistant micro-organisms and they can also disturb the beneficial microflora of the body. Thus, as an alternative to antibiotics, probiotics can be used, as they repopulate the beneficial microflora and reduce the pathogenic bacteria.

Skin hypersensitivity to sun light due to doxycycline ingestion causing hand partial-thickness burn

Drugs hypersensitivity should be remembered when placing patients on any form of medications. In this case we present skin hypersensitivity to sun light due to doxycycline ingestion causing hand partial-thickness burn.

Treatment of brucellosis: a systematic review of studies in recent twenty years

BACKGROUND

The treatment of human brucellosis is controversial. The purpose of this study was to search published clinical trial papers to provide a simple and effective treatment in brucellosis.

METHODS

Many studies on brucellosis treatment in a twenty- year span from 1993 to 2012 were searched in PubMed, Web of Science (ISI), Scopus, Google Scholar, Magiran, Iranmedex and SID. The studies that were searched and classified in groups according to combination therapy and monotherapy and their results in treatment outcome were compared. Regimens with lower treatment failure or relapse were considered as more suitable for brucellosis treatment.

RESULTS

The comparison of combined doxycycline and rifampicin (DR) with a doxycycline plus streptomycin (DS) favors the latter regimen. The combined doxycycline/cotrimoxazole (DCTM) showed similar effect with DR. The treatment with the combined regimen including quinolones was similar to DR but with higher relapse rates. Higher relapse rate was searched in monotherapy (13% vs. 4.8%) and in short-term (less than 4 weeks) treatment regimen (22% vs. 4.8%), respectively. Although in children, clinical trials were limited but showed cotrimoxazole plus rifampin for six weeks was the best treatment regimen.

CONCLUSION

In uncomplicated brucellosis in adult patients, doxycycline-aminoglycoside combination is the first choice with doxycycline- rifampin and doxycycline-cotrimoxazole should be the alternative regimens. The other oral regimens including quinolones may be considered as alternatives. Cotrimoxazole plus rifampin for six weeks may be the regimen of choice for the treatment of patients younger than 8 years old. Gentamicin for 5 days plus cotrimoxazole for six weeks may be a suitable alternative regimen.

Tetracyclines and neuromuscular disorders

Tetracyclines are a class of antibiotics which could act as neuroprotective molecules in several neurological disorders, such as Huntington disease, Parkinson disease, stroke and multiple sclerosis. The main biological effects of tetracyclines are the inhibition of microglial activation, the attenuation of apoptosis and the suppression of reactive oxygen species production. The anti-apoptotic effect of tetracyclines involves the mitochondrion, and the major target for neuroprotective effects of tetracyclines lies within the complex network that links mitochondria, oxidative stress and apoptosis.

Neuromuscular disorders are due to dysfunction of motor neurons, peripheral nerves, neuromuscular junction, or skeletal muscle itself. Animal studies have shown that minocycline could play neuroprotective effects in amyotrophic lateral sclerosis, but these positive findings have not been replicated in patients. Other neuromuscular disorders which tetracyclines may benefit are Guillain-Barré syndrome and other neuropathies, muscular dystrophies and mitochondrial disorders. However, well-designed double-blind controlled trials are still needed. Further studies are strongly needed to establish the most appropriate timing and dosage, as well as the indications for which tetracyclines could be effective and safe.

Here, we review the neuroprotective effects of tetracyclines in animal models, the clinical studies in humans, and we focus on their potential application in patients with neuromuscular disorders.

Simultaneous Esophageal and Gastric Ulceration Due to Doxycycline Ingestion: Case Report and Review of the Literature

Doxycycline induced mucosal injury to the esophagus and, rarely, stomach is an under appreciated cause of odonyphagia and chest pain. The diagnosis is dependent on a comprehensive exposure history and endoscopic evaluation. Once recognized, doxycycline induced ulceration is easily treated with cessation of the medication and gastric acid suppression. Our case report describes a classic description of doxycyline induced esophageal ulceration with the unusual endoscopic finding of a simultaneous antral ulcer.

A novel and rapid method to determine doxycycline in human plasma by liquid chromatography tandem mass spectrometry

A simple, rapid, specific and sensitive liquid chromatography tandem mass spectrometric method has been developed and validated for the determination of doxycycline from the human plasma. Doxycycline is extracted from human plasma by solid phase extraction. Demeclocycline was used as an internal standard. Detection was performed at transitions of 444.800→428.200 for doxycycline and 464.700→448.100 for demeclocycline using mass spectrometry. Chromatographic separation of analyte and internal standard were carried out using a reverse phase C18, column at 0.500 ml/min flow. The assay of doxycycline is linear over the range of 0.055-7.612 μg/ml, with a precision <14.83%, regression coefficient (r(2))=0.9961 and the limit of quantification in plasma for doxycycline was 0.055 μg/ml. Mean extraction recovery obtained was 95.55%. Samples are stable at room temperature for 6 h, processed samples were stable at least for 30.20 h and also stable at three freeze-thaw cycles. The method has been used to perform pharmacokinetic and bioequivalence studies in human plasma.

Cost effectiveness analysis of azithromycin and doxycycline for Chlamydia trachomatis infection in women: A Canadian perspective

OBJECTIVE

To assess the cost effectiveness of azithromycin versus doxycycline therapy for cervical Chlamydia trachomatis infections in Canada.

DESIGN

A predictive decision analytic model using previously published clinical and economic evaluations, expert opinion and costs of medical care in Canada.

POPULATION

A hypothetical cohort of 5000 women followed over 10 years.

INTERVENTIONS

Two diagnostic strategies were compared, laboratory confirmed diagnosis (LCD) and presumptive diagnosis (PD) of C trachomatis infection. Under each strategy, two treatment alternatives were analyzed, a single 1 g dose of azithromycin and a seven-day course of doxycycline as 100 mg twice daily.

RESULTS

Despite a fourfold higher acquisition cost, under base case conditions, for both diagnostic strategies, the azithromycin treatment alternative was more cost effective than the doxycycline alternative. For the LCD model, the cost per cure for patients receiving azithromycin was $184.76 compared with $240.59 for patients receiving doxycycline, resulting in an incremental cost of $55.83. For the PD model, the cost per cure for patients treated with azithromycin was $51.48 compared with $51.82, resulting in an incremental cost of $0.34. For the hypothetical cohort of 5000 women, the use of azithromycin translates into a projected annual cost savings of $279,150 and $1,700 for the LCD and PD models, respectively. In one-way sensitivity analyses for the LCD model, no clinically plausible changes in the base case estimates changed the results of the cost effectiveness outcome. In the PD model, clinically plausible changes in the probabilities of doxycycline cure, pelvic inflammatory disease, sequelae and chlamydia infection were found to alter the cost effectiveness outcome.

CONCLUSIONS

Based on the results from our model, the azithromycin strategy should be employed for the treatment of laboratory confirmed cases. However, for presumptive cases, azithromycin should be used only if the probabilities of C trachomatis and pelvic inflammatory disease are more than 19%, doxycycline effectiveness is less than 78%, or the cost of azithromycin is less than $19.00.