Effects of summer treatments against Varroa destructor on viral load and colony performance of Apis mellifera colonies in Eastern Canada.

Despite the use of various integrated pest management strategies to control the honey bee mite, Varroa destructor, varroosis remains the most important threat to honey bee colony health in many countries. In Canada, ineffective varroa control is linked to high winter colony losses and new treatment options, such as a summer treatment, are greatly needed. In this study, a total of 135 colonies located in 6 apiaries were submitted to one of these 3 varroa treatment strategies: (i) an Apivar® fall treatment followed by an oxalic acid (OA) treatment by dripping method; (ii) same as in (i) with a summer treatment consisting of formic acid (Formic Pro™); and (iii) same as in (i) with a summer treatment consisting of slow-release OA/glycerin pads (total of 27 g of OA/colony). Treatment efficacy and their effects on colony performance, mortality, varroa population, and the abundance of 6 viruses (acute bee paralysis virus [ABPV], black queen cell virus [BQCV], deformed wing virus variant A [DWV-A], deformed wing virus variant B [DWV-B], Israeli acute paralysis virus [IAPV], and Kashmir bee virus [KBV]) were assessed. We show that a strategy with a Formic Pro summer treatment tended to reduce the varroa infestation rate to below the economic fall threshold of 15 daily varroa drop, which reduced colony mortality significantly but did not reduce the prevalence or viral load of the 6 tested viruses at the colony level. A strategy with glycerin/OA pads reduced hive weight gain and the varroa infestation rate, but not below the fall threshold. A high prevalence of DWV-B was measured in all groups, which could be related to colony mortality.

Critical coupling in cavity-resonant integrated-grating filters (CRIGFs).

We experimentally demonstrate critical coupling in miniature grating-coupled resonators known as cavity-resonant integrated-grating filters (CRIGFs). Using previously proposed asymmetric grating coupler designs for non-linear CRIGFs, and introducing a dedicated variant of a coupled-modes theory model to estimate physical properties out of the measured reflection and transmission characteristics of these resonators, we demonstrate fine control over the in-and out-coupling rate to the resonator while keeping constant both the internal losses and the resonant wavelength. Furthermore, the critical coupling condition is also observed to coincide with the maximum enhancement of the second harmonic generation signal.

Cavity resonator-integrated guided-mode resonance filters with on-chip electro- and thermo-optic tuning.

Cavity resonator grating filters (CRIGFs) integrated on lithium niobate on insulator (LNOI) with electrical tuning elements are reported. The resonance wavelength of the filters is in the 780 nm range. Integrated thermo-optical tuning range of 2.5 nm is measured using integrated resistors, whilst a 0.7 nm electro-optical tuning range using capacitive metallic pads is achieved with ±400V drive voltage.

GaAs membrane PhC lasers threshold reduction using AlGaAs barriers and improved processing.

Active suspended membranes are an ideal test-bench for experimenting with novel laser geometries and principles. We show that adding thin AlGaAs barrier near the top and bottom Air/GaAs interfaces of the membrane significantly reduces the carriers non-radiative recombinations and decreases the threshold of test photonic crystal test lasers. We review the existing literature on photonic crystal membrane fabrication and propose an overview of the significant defects that can be induced by each fabrication step. Finally we propose a complete processing scheme that overcome most of these defects.

Conformal atomic layer deposition of RuOxon highly porous current collectors for micro-supercapacitor applications.

3D porous electrodes have been considered as a new paradigm shift for increasing the energy storage of pseudocapacitive micro-supercapacitors for on-chip electronics. However, the conformal deposition of active materials is still challenging when highly porous structures are involved. In this work, we have investigated the atomic layer deposition (ALD) of ruthenium dioxide RuO2on porous Au and Pt architectures prepared by hydrogen bubble templated electrodeposition, with area enlargement factors ranging from 400 to 10 000 cm2/cm2. Using proper ALD conditions, a uniform RuO2coverage has been successfully obtained on porous Au, with a specific electrode capacitance of 8.1 mF cm-2and a specific power of 160 mW cm-2for a minute amount of active material. This study also shows the importance of the chemical composition and reactivity of the porous substrate for achieving conformal deposition of a ruthenium oxide layer.

Varroa destructor and deformed wing virus interaction increases incidence of winter mortality in honey bee colonies.

Winter mortality of honey bee colonies represents a major source of economic loss for the beekeeping industry. The objectives of this prospective study were to estimate the incidence risk of winter colony mortality in southwestern Quebec, Canada and to evaluate and quantify the impact of the associated risk factors. A total of 242 colonies from 31 apiaries was selected for sampling in August 2017. The presence of Varroa destructor, Vairimorpha (Nosema) spp., Melissococcus plutonius, deformed wing virus (DWV), and viruses of the acute-Kashmir-Israeli complex (AKI complex) was investigated in each colony. Management practices of the various colonies were obtained from a questionnaire. The incidence risk of colony mortality during the winter of 2017-2018 was estimated to be 26.5% [95% confidence interval (CI): 15.4 to 40.3]. In logistic regression modeling of winter mortality in colonies, an interaction was discovered between V. destructor and DWV; the detection of ≥ 1 V. destructor mites per 100 bees was associated with higher odds of mortality (3.46, 95% CI: 1.35 to 8.90) compared to colonies with < 1 mite per 100 bees, but only in DWV-positive colonies. There were more colony losses in apiaries from beekeepers owning 1 to 5 colonies than in apiaries from beekeepers owning over 100 colonies, which suggests that beekeeper experience and/or type of management are important contributors to winter colony mortality. Assuming a causal relationship, the results of this study suggest that up to 9% of all colony mortalities in the population could have been prevented by reducing the level of V. destructor to < 1 mite per 100 bees in all colonies.

La mortalité hivernale des colonies d'abeilles est une cause importante de pertes économiques en apiculture. Cette étude prospective visait à estimer le risque d'incidence de mortalité hivernale des colonies d'abeilles et les facteurs de risque associés dans le sud-ouest du Québec (Canada). Au total, 242 colonies provenant de 31 ruches ont été sélectionnées en août 2017. La présence de Varroa destructor, de Vairimorpha (Nosema) spp., de Melissococcus plutonius, du virus des ailes déformées (DWV) et des virus du complexe AKI ont été évalués. Les pratiques de régie ont été obtenues selon un questionnaire. Le risque de mortalité des colonies à l'hiver 2017­2018 a été estimé à 26,5 % (95 % CI : 15,4 à 40,3). Dans un modèle de régression logistique, la détection de ≥ 1 mite de V. destructor par 100 abeilles était associée à des cotes plus élevées de mortalité (3,46, 95 % CI : 1,35 à 8,90) comparativement aux colonies avec < 1 mite par 100 abeilles, mais seulement pour les colonies positives au DWV. Les ruchers d'apiculteurs possédant entre 1 et 5 colonies présentaient une mortalité plus élevée comparativement à ceux d'apiculteurs possédant plus de 100 colonies, suggérant une influence de l'expérience ou du type de régie. En assumant une relation causale, les résultats de cette étude suggèrent que jusqu'à 9 % de toutes les mortalités hivernales observées dans la population auraient pu être prévenues en réduisant le niveau d'infestation par V. destructor à moins d'une mite per 100 abeilles dans toutes les colonies.(Traduit par les auteurs).

Prevalence of pathogens in honey bee colonies and association with clinical signs in southwestern Quebec, Canada.

Honey bees can be affected by a variety of pathogens, which impacts their vital role as pollinators in agriculture. A cross-sectional study was conducted in southwestern Quebec to: i) estimate the prevalence of 11 bee pathogens; ii) assess the agreement between beekeeper suspicion of a disease and laboratory detection of the causative pathogen; and iii) explore the association between observed clinical signs and pathogen detection in a colony. A total of 242 colonies in 31 apiaries owned by 15 beekeepers was sampled in August 2017. The prevalence of Varroa destructor detection was estimated as 48% for colonies and 93% for apiaries. The apparent prevalence of colonies infected by Nosema spp. and Melissococcus plutonius was estimated as 40% and 21%, respectively. At least 180 colonies were tested by polymerase chain reaction (PCR) for deformed wing virus (DWV), acute-Kashmir-Israeli complex (AKI complex), and black queen cell virus (BQCV), which were detected in 33%, 9%, and 95% of colonies, respectively. Acarapis woodi, Paenibacillus larvae, and Aethina tumida were not detected. Varroasis was suspected by beekeepers in 14 of the 15 beekeeping operations in which the mite was detected. However, no correlation was found between suspected European foulbrood and detection of M. plutonius or between suspected nosemosis and detection of Nosema spp. Colony weakness was associated with Nosema spore counts of at least 0.5 × 106 per bee. Melissococcus plutonius was more frequently detected in colonies showing scattered brood.

Les abeilles mellifères peuvent être affectées par plusieurs agents pathogènes, impactant leur rôle vital de pollinisateur en agriculture. Une étude transversale a été réalisée dans le sud-ouest du Québec afin 1) d'estimer la prévalence de onze agents pathogènes de l'abeille, 2) d'évaluer l'accord entre la suspicion d'une maladie par l'apiculteur et la détection de l'agent causal, 3) d'explorer les associations entre les signes cliniques et la détection d'un agent pathogène dans une colonie. Au total, 242 colonies de 31 ruchers appartenant à 15 apiculteurs ont été échantillonnées en août 2017. La prévalence de Varroa destructor a été estimée à 48 % pour les colonies et à 93 % pour les ruchers. La prévalence apparente de colonies infectées par Nosema spp. ou Melissococcus plutonius a été estimée à respectivement 40 % et 21 %. Le virus des ailes déformées, le complexe viral AKI et le virus de la reine noire ont été détectés dans respectivement 33 %, 9 % et 95 % dans des 180 colonies testées par PCR. Acarapis woodi, Paenibacillus larvae et Aethina tumida n'ont pas été détectés. La varroase était suspectée par les apiculteurs de 14 des 15 entreprises où la mite a été détectée. Aucune corrélation n'a été trouvée entre la suspicion de loque européenne et la détection de M. plutonius ou entre la suspicion de nosémose et la détection de Nosema spp. La faiblesse des colonies a été associée à des comptes de Nosema d'au moins 0,5 × 106 spores par abeille. Melissococcus plutonius était plus fréquemment détecté parmi les colonies présentant du couvain en mosaïque.(Traduit pas les auteurs).

Analytical validation of a portable human Accu-Chek glucometer in honeybee hemolymph.

Glucose and trehalose are the main energy sources used by honeybees (Apis mellifera) for daily activities. However, there is no validated point-of-care method to reliably measure both sugars. We performed an analytical validation of a portable human glucometer (Accu-Chek; Roche) for glucose measurement in honeybee hemolymph compared to a reference method (GluCH, UniCel DxC 600; Beckman Coulter). We used 30 pooled hemolymph samples collected from the antennae of anesthetized honeybees and diluted 1:4 in 0.9% saline. We evaluated dilution linearity, spike recovery, and inter- and intra-assay imprecision. Glucose concentration was measured over time (2 h, 4 h, 8 h, 12 h, 1 d, 2 d, 3 d, 7 d, 21 d, 28 d) at various storage temperature (25°C, 4°C, -20°C, -80°C). The trehalose concentration was measured indirectly by trehalase hydrolyzation. Glucose concentrations measured by both instruments had a strong correlation (0.985, p < 0.0001) and a bias of -7.33 mmol/L (±1.96SD: 13.70 to -28.36), with linear agreement at <20 mmol/L (physiologic value: 100 mmol/L). The accuracy of the glucometer decreased at >20 mmol/L. Recovery of 115-130% of diluted spikes indicated good specificity. Inter- and intra-assay imprecision were 2.50% and 2.21%, respectively. Glucose concentrations fluctuated in stored samples dependent on time and temperature; however, glucose concentrations were constant with storage at -80°C for ≥28 d. The Accu-Chek glucometer is an adequate instrument to measure honeybee glucose concentration in hemolymph diluted with 0.9% NaCl, with good accuracy and precision at <20 mmol/L. Hemolymph storage at -80°C is suitable for long-term conservation of glucose.

Evaluation of spring organic treatments against Varroa destructor (Acari: Varroidae) in honey bee Apis mellifera (Hymenoptera: Apidae) colonies in eastern Canada.

The objective of this study was to measure the efficacy of two organic acid treatments, formic acid (FA) and oxalic acid (OA) for the spring control of Varroa destructor (Anderson and Trueman) in honey bee (Apis mellifera L.) colonies. Forty-eight varroa-infested colonies were randomly distributed amongst six experimental groups (n = 8 colonies per group): one control group (G1); two groups tested applications of different dosages of a 40 g OA/l sugar solution 1:1 trickled on bees (G2 and G3); three groups tested different applications of FA: 35 ml of 65% FA in an absorbent Dri-Loc(®) pad (G4); 35 ml of 65% FA poured directly on the hive bottom board (G5) and MiteAwayII™ (G6). The efficacy of treatments (varroa drop), colony development, honey yield and hive survival were monitored from May until September. Five honey bee queens died during this research, all of which were in the FA treated colonies (G4, G5 and G6). G6 colonies had significantly lower brood build-up during the beekeeping season. Brood populations at the end of summer were significantly higher in G2 colonies. Spring honey yield per colony was significantly lower in G6 and higher in G1. Summer honey flow was significantly lower in G6 and higher in G3 and G5. During the treatment period, there was an increase of mite drop in all the treated colonies. Varroa daily drop at the end of the beekeeping season (September) was significantly higher in G1 and significantly lower in G6. The average number of dead bees found in front of hives during treatment was significantly lower in G1, G2 and G3 versus G4, G5 and G6. Results suggest that varroa control is obtained from all spring treatment options. However, all groups treated with FA showed slower summer hive population build-up resulting in reduced honey flow and weaker hives at the end of summer. FA had an immediate toxic effect on bees that resulted in queen death in five colonies. The OA treatments that were tested have minimal toxic impacts on the honey bee colonies.

Beekeeping management practices in southwestern Quebec.

The growing number of honey bee colonies and beekeepers in Canada has led to a great diversity of beekeeping practices. All beekeeping operations, however, need to implement consistent management measures for the control of diseases. The objective of this study was to document the actual disease management practices of beekeeping productions in southwestern Quebec, Canada. A survey was conducted to describe management practices used by 15 beekeepers who own 1824 colonies in that area. Data were obtained by telephone interviews. When infectious diseases were suspected, beekeepers generally avoided using potentially toxic acaricides and chemical treatments associated with antimicrobial resistance and instead used preventive, physical or management methods, although laboratory diagnosis was rarely used. This study highlights the wide variety of operation sizes, activities, and disease management strategies among beekeepers in southwestern Quebec. It identifies the need to encourage the use of services available to them and to propose a standardized preventive medical approach for field veterinarians to avoid the spread of infectious diseases.

Le nombre croissant de colonies d'abeilles mellifères et d'apiculteurs au Canada a conduit à une grande diversité de pratiques apicoles. Cependant, toutes les opérations apicoles doivent mettre en oeuvre des mesures de gestion cohérentes pour lutter contre les maladies. L'objectif de cette étude était de documenter les pratiques actuelles de gestion des maladies dans les exploitations apicoles situées au sud-ouest du Québec, Canada. Une enquête a été menée pour décrire les pratiques de régie utilisées par 15 apiculteurs possédant 1824 colonies dans cette région. Les données ont été obtenues par des entretiens téléphoniques. Lorsque des maladies infectieuses étaient suspectées, les apiculteurs évitaient généralement d'utiliser des acaricides potentiellement toxiques et des traitements chimiques associés à la résistance aux antimicrobiens et utilisaient à la place des méthodes préventives, physiques ou de gestion, bien que les diagnostics en laboratoire étaient rarement utilisés. Cette étude met en évidence la grande variété de tailles d'entreprises, d'activités et de stratégies de gestion des maladies de l'abeille par les apiculteurs du sud-ouest du Québec. Il identifie la nécessité d'encourager l'utilisation des services offerts aux apiculteurs et de proposer une approche médicale préventive standardisée aux vétérinaires pour éviter la propagation de maladies infectieuses.(Traduit par Gabrielle Claing).

Phylogenetic analysis of rubella viruses involved in congenital rubella infections in France between 1995 and 2009.

Rubella is an acute infectious disease that normally has a mild clinical course. However, infections during pregnancy, especially before week 12 of gestation (WG), can cause severe birth defects known as congenital rubella syndrome (CRS). The aim of this study was to perform genotyping and molecular characterization of rubella viruses involved in congenital infections in France over the past 15 years (1995 to 2009). Amniotic fluid (AF) specimens (n = 80) from pregnant women with congenital rubella infections (CRI) before week 20 of gestation, and a few other samples available from children/newborns with CRS (n = 26), were analyzed. The coding region of the rubella virus E1 gene was amplified directly from clinical specimens by reverse transcriptase PCR, and the resulting DNA fragments were sequenced. Sequences were assigned to genotypes by phylogenetic analysis with rubella virus reference sequences. Sufficient E1 gene sequences were obtained from 56 cases. Phylogenetic analysis of the sequences showed that at least five different genotypes (1E, 1G, 1B, 2B, and 1h) were present in France and were involved in congenital infections, with a strong predominance of genotype 1E (87%). This is one of the very few comprehensive studies of rubella viruses involved in CRI. The results indicated that over the past 15 years, multiple introductions of the dominant genotype E caused most of the CRI cases in France. A few sporadic cases were due to other genotypes (1B, 1G, 1h, 2B).

Evaluation of different cytomegalovirus (CMV) DNA PCR protocols for analysis of dried blood spots from consecutive cases of neonates with congenital CMV infections.

Two protocols for the extraction of cytomegalovirus (CMV) DNA and two methods for the amplification of CMV DNA in dried blood spots were evaluated for the retrospective diagnosis of congenital CMV infection. During the period from 1996 to 2006, a urine screening program detected 76 congenitally infected neonates. Stored Guthrie cards with blood from 55 cases and 12 controls were tested. Two spots of dried blood were cut from each card and evaluated in two centers. CMV DNA was extracted from a whole single spot. Center 1 used phenol-chloroform extraction and ethanol precipitation followed by a conventional PCR. Center 2 used the NucliSens easyMAG automated DNA/RNA extraction platform (bioMérieux) followed by a real-time PCR. For evaluation of the extraction method, DNA extracted from each blood spot was evaluated by the amplification method used by the collaborating center. The sensitivities were 66% for center 1 and 73% for center 2. None of the controls were positive. A sensitivity as high as 82% could be obtained by combining the most sensitive extraction method (the phenol-chloroform procedure) with the most sensitive PCR method (real-time PCR). The detection rate was not influenced by the duration of storage of the spots. The sensitivity was higher with blood from congenitally infected cases due to a primary maternal CMV infection, regardless of the protocol used. However, the difference reached significance only for the least-sensitive protocol (P = 0.036).

Risk factors and impacts of clinical and subclinical mastitis in commercial meat-producing sheep flocks in Quebec, Canada.

We conducted a prospective observational study on clinical and subclinical mastitis in 30 commercial meat-producing sheep flocks from 2 regions of the province of Quebec, Canada. A total of 2,792 ewes selected in late gestation were followed from lambing to weaning of lambs. The incidence of clinical mastitis for the total lactation period (average of 58 days) ranged among flocks from 0 to 6.6%, with a median of 1.2%. The most frequently isolated bacteria from the cases of clinical mastitis, in pure or mixed culture, were Mannheimia haemolytica (26%), Staphylococcus aureus (23%), and coagulase-negative staphylococci (17%). Incidence of clinical mastitis was higher in ewes that gave birth to 3 or more lambs and from the Estrie region, and was associated with an increase in ewe mortality, an increase in lamb mortality at the litter level, and a decrease in lamb's weaning weight for lambs born in multiple litter size or from ewes >or=4 years old. Among 354 selected ewes with clinically normal udder at the end of lactation, 28.8% had potentially pathogenic bacteria isolated from milk. The most prevalent bacteria were S. aureus (9.3%) and coagulase-negative staphylococci (9.3%). The risk of having a positive culture in at least one half was different between the two regions. Prevalence of ewes (n=261) with California Mastitis Test (CMT) positive result in at least one half was 24.1 and 14.9% using a cut-off of >or=1+ and >or=2+, respectively. Prevalence of culture-positive udder halves was 11.7% for CMT-negative compared with 53.6% for CMT 3+ halves. CMT status was positively associated with the isolation of coagulase-negative staphylococci, M. haemolytica, S. aureus, and various Streptococcus species, but not with other isolated bacteria. Additionally, prevalence of CMT-positive halves was higher in ewes from the Estrie region, aged of >or=4 years versus 1 year, having clinical mastitis previously detected in the lactation and/or with low body condition score. Lamb weaning weight was associated with CMT status of ewes, while weaning weight was not associated with milk culture results. More research is needed to understand the dynamic of milk SCC and IMI in ewes from meat-producing flocks, its economical impact and best ways to control it.

Non-clinical pharmacology and safety evaluation of TH9507, a human growth hormone-releasing factor analogue.

TH9507, an analogue of human growth hormone-releasing factor (hGRF1-44NH2) minimally modified by addition of a trans-3-hexenoyl moiety to Tyr1 of the amino acid sequence, was found to be resistant to dipeptidyl aminopeptidase-IV deactivation. Compared to natural hGRF1-44NH2, the modification slowed the in vitro degradation of the peptide in rat, dog and human plasma and prolonged the in vivo plasma elimination kinetics of immunoreactive TH9507. Plasma growth hormone and insulin-like growth factor-1 (IGF-1) markedly increased in pigs, rats and dogs after daily repeat intravenous or subcutaneous injections of TH9507 at doses up to 600 microg/kg. Subchronic toxicity studies in rats and dogs with TH9507 treatment for up to 4 months showed a significant, but not dose-related, increase in body weight gain associated with increased biomarker response. Although TH9507 was well tolerated by both rats and dogs, a more pronounced anabolic effect and more evident (reversible) adverse effects (liver and kidney findings, anaemia, clinical chemistry changes, organ weight effects) were observed in dogs after repeat daily subcutaneous injections, which were attributed to prolonged exposure to supraphysiological levels of growth hormone and/or IGF-1. In both rats and dogs, toxicokinetic evaluations indicated that exposure to immunoreactive TH9507 was dose related after both routes of administration. The apparent elimination t1/2 in dogs ranged from 21 to 45 min. In conclusion, TH9507 is a modified hGRF peptide having enhanced potency and duration of action. The adverse treatment-related effects in dogs appear to be associated with sustained exposure to supraphysiological levels of growth hormone and IGF-1 induced by prolonged TH9507 treatment.

Growth hormone-releasing factor: structural modification or protection for more potent analogs.

Growth hormone-releasing factor was discovered in 1982 by Guillemin and has been subjected to intense investigations because of its huge potential applications. The major concerns encountered with the native molecules were their short half-lives in vivo in many species including man, precluding the practical use of these peptides for medical or production purposes. Many efforts to produce analogs of shorter length, more resistant to degradation and having higher affinity to the receptors have been made during the last decades. The present paper presents a quick review of the work done to produce such analogs.

Characterization of crosslinked high amylose starch matrix implants. 1. In vitro release of ciprofloxacin.

The objective of this study was to characterize in vitro the potential of crosslinked high amylose starch (CLHAS) as an implant matrix for the delivery of ciprofloxacin (CFX). Direct compression of dry blends of four different matrices: control CLHAS; CLHAS with 1% hydrogenated vegetable oil (HVO); and CLHAS with 10 or 20% hydroxypropylmethylcellulose (HPMC), each of them with three CFX loadings (2.5, 5.0 and 7.5%) was performed to prepare twelve implant formulations. All CLHAS implants were used for 24-h dissolution tests to evaluate swelling, erosion, water uptake and CFX release. Additionally, 1%-HVO- CLHAS implants were used for an extended dissolution test. The presence of HPMC in the matrix increased CFX release rate, swelling, erosion and water uptake in a concentration-dependent manner whereas HVO had no effect. With increasing drug loading, a decrease of cumulative CFX percent release was observed in both 24-h and extended dissolution tests. Of the different formulations tested, CLHAS implants with 1% HVO and 7.5% CFX provided the longest period of drug delivery without any initial burst effect.

Characterization of crosslinked high amylose starch matrix implants. 2. In vivo release of ciprofloxacin.

The purpose of this study was to develop a crosslinked high amylose starch (CLHAS) matrix implant as a sustained antimicrobial delivery system for local prevention and/or treatment of osteomyelitis. Implants (200 mg) of CLHAS containing 2.5% (5 mg), 7.5% (15 mg), 15.0% (30 mg) and 20.0% (40 mg) of ciprofloxacin (CFX), were prepared by direct compression of dry blends. Rabbits were administered six 2.5, two 7.5, one 15.0 or one 20.0%-CFX implants along the femur between the quadriceps and biceps femoris muscles to determine systemic (serum) versus local (muscle and bone) CFX concentrations over 1 month. Blood samples were taken throughout the study for CFX assay. Muscle and femur were collected at 3, 7, 14, 21 and 28 days after implantation for host response evaluation and CFX assay. Residual polymer was explanted to determine the remaining dose of CFX. All animals remained healthy during the study. Local tissue reaction was mild and limited to the implantation site. Serum CFX concentrations remained low regardless of implant loading. Increased drug loading resulted in a higher and longer release of CFX in muscle and in bone. Local CFX concentrations were detected largely in excess of the MIC over 28 days with 20.0%-CFX implants. More residual CFX in polymer was detected over a longer period of time at high loading. These results strongly support the development of CLHAS implants for local antibacterial therapy.

Prevention and treatment of experimental osteomyelitis in dogs with ciprofloxacin-loaded crosslinked high amylose starch implants.

Crosslinked high amylose starch (CLHAS) matrix was used as a biodegradable drug delivery implant for the prevention and treatment of osteomyelitis. Thirty-two dogs underwent the femoral insertion of a screw inoculated with Staphylococcus aureus and were then randomly assigned to four groups: (A) prevention with ciprofloxacin-CLHAS implants, (B) surgical debridement (positive control), (C) surgical debridement and oral ciprofloxacin treatment and (D) surgical debridement and treatment with ciprofloxacin-CLHAS implants. At week 4 the osteomyelitis was confirmed, the infected site debrided and respective treatments initiated for groups B, C and D. Radiographs, macroscopic evaluations, bacterial cultures and histopathological examinations were used to evaluate the femora at week 10. Femora from preventive group A were almost normal. Dogs of both ciprofloxacin treatment groups C and D showed better bone healing, less periosteal reaction and less screw mobility than dogs from group B. Eradication of infection was observed at proximal/distal sites in B: 25%/12%, C: 37%/62% and D: 62%/75%. Both ciprofloxacin treated groups improved radiographically from week 4 to week 10. Periosteal and marrow neutrophilic and lymphoplasmocytic infiltrations were less severe in groups C and D versus group B. These data suggest that biodegradable ciprofloxacin-CLHAS implants are a safe and efficient modality for the prevention and treatment of osteomyelitis.

Characterization of subcutaneous Contramid implantation: host response and delivery of a potent analog of the growth hormone-releasing factor.

Cross-linked high amylose starch (Contramid) was investigated as a solid implant for evaluation of host response in mice and as a possible delivery system for a human growth hormone-releasing factor analog (Hex-hGRF) release profile in pigs. Seventy mice were administered subcutaneously one 3 mm diameter Contramid pellet and host reaction was evaluated over 6 months. Thirty pigs were divided into four groups. All animals of the three implanted groups were administered subcutaneously 15 mg Hex-hGRF, (1) one pure Hex-hGRF implant; (2) four 30/70 w/w Hex-hGRF/Contramid implants; or (3) eight 15/85 w/w Hex-hGRF/Contramid implants. The fourth group (n=6) was injected subcutaneously twice daily with 10 microg/kg of Hex-hGRF over 5 consecutive days. Serum insulin-like growth factor-I (IGF-I) was monitored over 1 month. In mice, no adverse reaction occurred after implantation. Macroscopic and microscopic inflammatory reactions were always localized. Polymorphonuclear cells (PMNs) and macrophages predominated within and around the pellets, respectively. Thin fibrovascular septas eventually subdivided Contramid pellets which were progressively phagocytosed by macrophages. In pigs, serum IGF-I concentrations were increased over a 10 day period in all implanted groups. The initial IGF-I peak observed in the daily injected group was avoided in both Contramid implant groups but not in the pure Hex-hGRF implant group. These encouraging results warrant the development of Contramid implants as a sustained delivery system for peptidic drugs.

Pulmonary delivery of TH9507, a growth hormone releasing factor analogue, in the dog.

A modified growth hormone releasing factor (GRF; TH9507), a 44 amino acid peptide analogue of natural human growth hormone releasing factor, is being developed for the treatment of age-associated conditions resulting from diminished growth hormone (GH) secretion. The inhalation route of administration is being considered as an alternative to subcutaneous injection. A study was undertaken in dogs to investigate the absorption of TH9507 following pulmonary delivery. Male beagle dogs were administered TH9507 by intratracheal dry powder insufflation and subcutaneous injection at doses of approximately 375 and 38microg/kg, respectively. In a separate study, male and female dogs received 100microg/kg intravenously. Blood samples were collected at selected sampling times after dosing and plasma levels of TH9507 were measured by radioimmunoassay. The bioavailability by the inhaled route was 41% relative to subcutaneous dosing, with an absolute bioavailability estimated at 13%. No significant difference was observed for the terminal half-life of TH9507 after intratracheal (39min) and subcutaneous (26min) administrations. The mean residence time (MRT) was greater following intratracheal administration (74min versus 52min; P<0.01). These data indicate that the delivery of the TH9507 by the inhalation route may provide a suitable alternative to subcutaneous injection.