Correlations Between Clinicopathological Features and the Vegetative Nervous System in Gastric Cancer.

Gastric cancer currently represents one of the most important public health problems. Recent studies have demonstrated the existence of strong correlations between the vegetative nervous system and the role it plays in the initiation of the oncogenetic process and the progression of cancer. The purpose of this paper is to demonstrate the involvement of the sympathetic and parasympathetic vegetative nervous system in the evolution of gastric cancer, according to the stage of tumor differentiation. In this current paper we have included a number of four patients diagnosed with gastric cancer post UGI (Upper Gastrointestinal Endoscopy) and have analyzed relations that exist between the tumor differentiation degree and the metanephrine and normetanephrine serum level in the blood of the patients. Following the research, we have observed an increased value of the metanephrine and normetanephrine serum level in the patient which displayed the lowest degree of differentiation.

Is a family-centred initiative a family-centred service? A case of a Conductive Education setting for children with cerebral palsy.

BACKGROUND: From the moment a child is diagnosed as having cerebral palsy, families have to cope on a daily basis with the multifaceted challenges of life-long disability management. Family-centred service is embraced as a 'best practice' model because of accumulating evidence supporting its positive influence on parents and children's outcomes. Nevertheless, research comparing parent and provider perspectives on family-centred practices of educational service providers in education settings is scarce. The aims of this study were to compare the extent to which parents and conductors experience the service delivery in Tsad Kadima, the Association for Conductive Education in Israel, as being family-centred, as well as comparing parents' perception of different educational settings as being family-centred. METHODS: Measurements of family-centeredness, the Israeli Measure of Processes of Care for families (MPOC-20) and for service providers (MPOC-SP), were administrated to 38 teacher conductors and 83 families of children with cerebral palsy (aged 1-14), from different conductive educational settings. RESULTS: Parents and conductors perceive Conductive Education service as being highly family centred in most domains, rating respectful and supportive care the highest and providing general information the lowest, thus indicating an area where improvements should be made. Parents perceived the service they receive to be more family-centred than conductor's perception about their own activities. In addition, educational setting (day care, pre-school and school) was found to be associated with parent's scores. CONCLUSIONS: The current study, which is the first to examine family-centred service provision in a conductive special education setting, from the perspectives of both parents and conductors, provides significant evidence for high-quality services in these settings.

Efficacy of Milbemax (milbemycin oxime + praziquantel) in the treatment of dogs experimentally infected with Crenosoma vulpis.

Crenosoma vulpis, the fox lungworm, infects wild and domestic canids and is a cause of chronic respiratory disease in dogs in North America and Europe. The objective of this study was to determine the efficacy of milbemycin oxime (0.5mg/kg)/praziquantel (5mg/kg) (Milbemax; Novartis Animal Health, Inc.) against C. vulpis infection in a randomized, blinded, placebo-controlled study using experimentally infected dogs. Sixteen beagles (8 males, 8 females) were each given 100 infective third-stage larvae of C. vulpis. Fecal samples were examined for first-stage larvae by quantitative Baermann examination pre-exposure and at days 21, 28, 35, 42 and 49 post-infection (PI). All of the dogs were shedding larvae in the feces at 21 days PI. The dogs were randomly assigned to one of two groups. At 28 days PI, Group 1 (4 males, 4 females) received placebo only while Group 2 (4 males, 4 females) received a single treatment of milbemycin oxime (0.5mg/kg) and praziquantel (5mg/kg). The 16 dogs were euthanized and necropsied at 49 days PI. Lungs were removed, assessed for gross lesions (graded on a subjective scale 0-3 with 0 being normal) and C. vulpis were collected by lung-flush and counted. Samples of lung tissue were preserved for evaluation of histopathology and the lesions graded on a subjective scale (0-3 with 0 being normal). Gross and histopathology lesions were detected in all 8 untreated Group 1 dogs with mean subjective lesion scores of 1.8 ± 0.7 (range 1-3) and 3.0 ± 0.0 (range 3), respectively. Gross lesions were observed in 3/8 and histopathology lesions in all 8 of the treated Group 2 dogs with mean subjective lesion scores of 0.4 ± 0.5 (range 0-1) and 1.3 ± 0.4 (range 1-2), respectively. The mean (geometric) number for adult C. vulpis recovered in untreated dogs was 48.3 (range 25-70) compared with 0.65 (range 0-2) in animals treated with Milbemax. The resulting efficacy against C. vulpis was 98.7%. The number of C. vulpis was significantly lower for treated dogs than the burden in the untreated group (p=0.0002). A single dose of Milbemax (milbemycin oxime 0.5mg/kg+praziquantel 5mg/kg) was highly effective for the treatment of patent C. vulpis infection in dogs. A dosing interval for the prevention of clinical disease in dogs exposed to natural infections has not been established.

The efficacy of milbemycin oxime against pre-adult Spirocerca lupi in experimentally infected dogs.

The aim of this investigation was to determine the efficacy of milbemycin oxime in preventing the oesophageal encapsulation of Spirocerca lupi, following the experimental infection of dogs. Two studies were conducted which involved a total of 21 purpose-bred Beagles. Each dog was infected with approximately 40, third stage infective S. lupi larvae. The larvae were dissected from scarabaeid beetles that had been collected from areas endemic for spirocercosis. In the first study, milbemycin oxime (minimum dose 0.5mg/kg body weight) was administered to seven dogs on day 30 post-infection. Seven other dogs served as untreated controls. In the second study, milbemycin oxime (also at a minimum dose of 0.5mg/kg body weight) was administered to four of seven infected dogs on day 28 post-infection. Treatment was repeated at 14- or 28-day intervals. All of the dogs, from both studies, were euthanized 168 or 169 days after infection. All S. lupi were recovered, and lesions in the thoracic aorta and oesophagus were described and quantified. A single treatment with milbemycin oxime was 79.8% effective in preventing the establishment of S. lupi in the oesophagus. This treatment significantly (p<0.05) reduced both the number of S. lupi within the oesophagus and the size of the oesophageal nodules. The efficacy of anthelmintic treatment was increased to 100% when repeat doses of milbemycin oxime were administered at 14- or 28-day intervals. These repeat treatments completely prevented the establishment of S. lupi within the oesophagus and thereby averted the development of oesophageal nodules. As expected, none of the treatment protocols reduced S. lupi related damage within the aorta because the administration of milbemycin oxime only began after the larvae had completed their first stage of migration.

The use of milbemycin oxime in a prophylactic anthelmintic programme to protect puppies, raised in an endemic area, against infection with Spirocerca lupi.

Spirocerca lupi is primarily a parasite of dogs and other carnivores. Clinical signs of infection are regurgitation, vomiting, weight loss, coughing and dyspnoea. Sudden death can also occur due to a ruptured aortic aneurysm. In this study, the Eastern Cape Province of South Africa was identified as an area with a high prevalence of S. lupi. A subsequent investigation, to evaluate the efficacy of milbemycin oxime as a prophylactic agent for canine spirocercosis, involved 58 puppies that were raised in this area in accordance with local husbandry procedures. Approximately half of the puppies served as untreated controls. Puppies in the treatment group received milbemycin oxime (minimum dose of 0.5mg/kg body weight) when they were between 2 and 6 weeks old. They then received five further treatments at approximately 28-day intervals. The treatment was orally administered in tablet form. After the sixth treatment, puppies from both the treated and control groups were euthanized and post-mortem examinations were performed. Twenty-four out of 27 dogs in the untreated control group had become infected by S. lupi. In comparison, only 19 out of 31 dogs in the treatment group had evidence of spirocercosis as demonstrated by aortic nodules. The prophylactic regimen reduced the severity of aortic lesions and prevented 86.5% of S. lupi from becoming established in the thoracic aorta. It also prevented 89.4% of S. lupi from becoming established in the oesophagus and significantly reduced the number of oesophageal nodules. Milbemycin oxime markedly reduced the level and severity of S. lupi infection in treated puppies raised in an endemic area of South Africa. It deserves further evaluation as a potential prophylactic treatment for spirocercosis.

Therapeutic and prophylactic efficacy of milbemycin oxime (Interceptor) against Thelazia callipaeda in naturally exposed dogs.

Two trials were conducted to evaluate the therapeutic and prophylactic activity of milbemycin oxime (Interceptor, Novartis Animal Health) against the eye-worm Thelazia callipaeda (Spirurida, Thelaziidae) infection. In Trial 1, the therapeutic efficacy of milbemycin oxime was evaluated in 55 naturally infected dogs treated with min. 0.5mg/kg milbemycin oxime. The dogs were clinically examined for the presence of eyeworms before and again 7 days after treatment. Dogs still positive were given a second treatment and re-checked again a week later. Forty-eight of the 55 dogs tested negative 1 week after treatment (87.3% reduction of infection rate). Following the second treatment 6 of these 7 dogs tested negative 1 week later resulting, after two treatments, in a reduction of infection rate of 98.2%. In Trial 2, the prophylactic efficacy of milbemycin oxime was evaluated in 60 uninfected dogs. Thirty dogs were treated with milbemycin oxime monthly from June to November with the recommended dose rate for the prevention of heartworm disease (> or =0.5mg/kg), 30 dogs served as untreated controls. At the end of the trail 1 dog in the treated group and 10 dogs in the control group became infected during the trial. The incidence of infection differed significantly between treated and control dogs (p=0.0056). The efficacy of the prophylactic use of a monthly treatment with milbemycin oxime showed 90% efficacy in reducing T. callipaeda infection rate.

Efficacy of a milbemycin oxime-praziquantel combination product against adult and immature stages of Toxocara cati in cats and kittens after induced infection.

Two studies were performed to examine the efficacy of milbemycin oxime against fourth-stage larvae or adults of Toxocara cati. In the study to determine efficacy against fourth-stage larvae, 20 domestic shorthair cats were inoculated with 500 embryonated eggs. Four weeks after inoculation, the animals were allocated to two groups, and cats in one group were treated with medicated tablets containing 4 mg milbemycin oxime and 10mg praziquantel (MILBEMAX) and cats in the other group with placebo tablets. Seven days after treatment the animals were euthanatized and necropsied for worm counting. The number of worms found was significantly (p=0.0002) lower in cats treated with medicated tablets than in cats treated with placebo tablets. The reduction in the number of worms was 96.53%. In the study to determine efficacy against mature adult worms, 13 kittens were inoculated with T. cati embryonated eggs. On day 45 after inoculation and after the infection had been confirmed through faecal examinations for 11 out of the 13 animals, the 11 infected animals were allocated to two groups and treated as in the first study. Seven days after treatment, all animals were euthanatized and necropsied for worm counting. The number of worms found was significantly (p=0.0043) lower in kittens treated with medicated tablets than in kittens treated with placebo tablets. The reduction in the number of worms was 95.90%. No adverse effects were recorded during either study. It is concluded that the milbemycin oxime-praziquantel tablets that were used are efficacious for the control of T. cati infections in cats.

Personal assistance, adaptations and participation in students with cerebral palsy mainstreamed in elementary schools.

PURPOSE: The aims of this study were to examine differences in level of participation of students with CP in full inclusion (FI group) as compared to self-contained classes (SC group), differences in the task supports provided for these two groups, the interrelationships between assistance and adaptation provided and the differential impact of physical task supports vs. cognitive/behavioural task supports on participation. METHOD: 148 elementary school students were divided into two groups: 100 fully included (FI) students with CP, and 48 students with CP in self-contained classes (SC). The School Function Assessment (SFA) was used as the main measurement for assessing the levels of participation and functional performance profiles. RESULTS: Statistically significant differences (p < 0.0001) were found between the two groups on all scales (physical and cognitive/behavioural assistance and adaptations). Supports provided to the SC group were significantly greater than to the FI group and physical task supports provided to both groups were significantly greater than cognitive/behavioural supports. Pearson correlations and Smallest Space Analyses (SSA) revealed significant (p < 0.01) moderate to strong correlations (0.57 > r < 0.77) between all four task supports, and between provided task supports and participation (0.66 > r < 0.82). CONCLUSIONS: This study's focus enhances our understanding of the impact of task supports to the various factors contributing to the dimensions of the ICF, as well as their interrelationship with participation. Devises and cognitive and behavioural adaptations are required in a wider manner in addition or alternative to physical assistance by adults if we are to increase the chance of students with severe CP to become participatory for academic and social tasks required in school.

Comparative effects of milbemycin oxime-based and febantel-pyrantel embonate-based anthelmintic tablets on Toxocara canis egg shedding in naturally infected pups.

The effect of two treatment programmes on egg shedding in dogs naturally infected with Toxocara canis, one based on a milbemycin oxime-praziquantel-lufenuron combination (SENTINEL) Spectrum; Group 1) and the other based on a febantel-pyrantel embonate-praziquantel combination (DRONTAL) Plus; Group 2), was compared in a study involving 104 suckling pups from three different kennels. The animals in Group 1 were treated at a minimum milbemycin oxime dose of 0.5 mg/kg bw starting at 2 weeks of age and subsequently every 4 weeks until reaching 26 weeks of age. The animals in Group 2 were treated every 2 weeks from week 2 until week 12 of age and then once at week 26 at a minimum febantel and pyrantel embonate dose of 15.0 and 14.4 mg/kg bw, respectively. Toxocara egg counts were determined fortnightly starting at 2 weeks of age and continuing until 26 weeks of age for every pup. Any adverse drug event was recorded during the trial. Both treatment programmes significantly reduced the zoonotic Toxocara egg shedding and were well tolerated by the pups. The pups in Group 1 showed lower average faecal egg counts and were found more frequently shedding no eggs than the pups in Group 2.

Participation and activity performance of students with cerebral palsy within the school environment.

PURPOSE: The aims of this study were to investigate the levels of participation and activity performance of students with cerebral palsy within the inclusive school context, to explore the relationships between these two aspects of function and to identify predictors of participation among the various school activities. METHOD: Two hundred and forty-eight elementary school students were divided into three groups: 100 fully included (FI) students with CP, 100 matched by class and gender typical students (TS) and 48 students with CP in self-contained classes (SC). The School Function Assessment (SFA) was used as the main measurement for assessing the levels of participation and functional performance profiles. RESULTS: Significant differences (P<0.0001) in levels of participation were evident across the three study groups using MANOVA and ANOVAs analyses, where the TS level was the highest and the SC was the lowest. Comparison of the mean score of the physical and the cognitive/behavioural tasks performance revealed similar results among the three groups. Positive Pearson correlations were obtained between participation and both motor and cognitive/behavioural activity performance in the FI and the SC groups. Regression models for the FI and the SC groups were found significant (P<0.0001) and explained above 69% of the participation variance with physical activity performance as the most predictive variable. CONCLUSIONS: Significant differences exist between participation and activity performance of typical students and students with CP included in regular schools. Moreover, activity performance limitations were found to impact on school participation. These findings stress the continuing need to provide rehabilitative intervention towards removing existing barriers within the inclusive environment.

Comparative speed of kill between nitenpyram, fipronil, imidacloprid, selamectin and cythioate against adult Ctenocephalides felis (Bouché) on cats and dogs.

Speed of kill and percentage kill of nitenpyram (CAPSTAR) was compared to fipronil (Frontline) spot-on), imidacloprid (Bayvantage/Advantage), selamectin (Stronghold/Revolution) and cythioate (Cyflee) against adult fleas on cats and dogs 3 and 8h post-treatment. Selamectin was used on dogs only; cythioate was used on cats only. Groups of eight cats and eight dogs (four males and four females each) were experimentally infested with 100 unfed fleas 1 day prior to treatment with the test products. One group of cats and one group of dogs served as control. Fleas were collected from four cats and four dogs in each group (two males and two females) by combing 3h after treatment, the remaining four cats or dogs were combed 8h after treatment. In cats cythioate treatment resulted in a mean efficacy of 62.4 and 97.4% at 3 and 8h post-treatment, respectively. Imidacloprid efficacy at the same times was 26.9 and 82.8%, whereas fipronil efficacy was 24.3 and 62.6% efficacy, respectively. In dogs mean efficacy 3 and 8h after treatment with selamectin was 39.7 and 74.4%; with imidacloprid efficacy was 22.2 and 95.7%, respectively and 35.9 and 46.5%, respectively after treatment with fipronil. Nitenpyram was 100% effective in cats and 99.1% effective in dogs within 3h of treatment and 100% effective in cats and dogs within 8h.

Evaluation of the efficacy of oral lufenuron combined with topical enilconazole for the management of dermatophytosis in catteries.

The efficacy of oral lufenuron, a chitin synthetase inhibitor, combined with topical enilconazole, was evaluated for the management of Microsporum canis infection in 100 cats housed in two catteries in France. The cats were treated with weekly rinses with enilconazole (0.2 per cent) for four weeks and, in each cattery, one group (A) was also treated with micronised griseofulvin (25 mg/kg administered orally twice a day for five weeks) and a second group (B) was treated with 60 mg/kg lufenuron administered orally once on day 0 and again after 30 days. All the cats were examined individually for cutaneous lesions and mycological cultures were made when the treatment began and after 15, 30, 60 and 90 days. In the first cattery, the cats' clinical scores after 30 and 60 days were significantly lower in group B than in group A. In both catteries and both treatment groups, the mean number of fungal colonies decreased rapidly during the first 15 days of treatment, remained stable for the following 45 days but increased from day 60 to the end of the experiment on day 90.

Interference dips in the single-crystal absorption spectrum of the ti-mu-fluoro-bis(trifluorochromate(III)) complex.

The lowest energy spin-allowed crystal field band of (Et(4)N)(3)Cr(2)F(9) shows a distinct interference dip at 15,000 cm(-1) with an approximate width of 200 cm(-1). This spectroscopic feature is due to spin-orbit coupling between the (2)E and (4)T(2) excited states and is analyzed with a set of two coupled potential energy surfaces. The minimum of the (4)T(2) potential surface is displaced along at least two normal coordinates. The modes involved cannot be directly determined from the unresolved absorption spectrum, but are obtained from Raman spectra and from the well-resolved spin-forbidden crystal field transition to the (2)A(1) state. The first mode with a frequency of 415 cm(-1) has predominant Cr-F stretching character; the second mode has a frequency of 90 cm(-1) and involves the entire Cr(2)F(9)(3-) dimer.

Ferromagnetic exchange in the ground and (4)A(1) excited states of (Et(4)N)(3)Fe(2)F(9). A magnetic and optical spectroscopic study.

The synthesis, crystal growth, magnetic susceptibility, and polarized optical absorption spectra in the visible and near UV of (Et(4)N)(3)Fe(2)F(9) are reported. From single-crystal magnetic susceptibility data and high-resolution absorption spectra in the region of the (6)A(1) --> (4)A(1) spin-flip transition, exchange splittings in the ground and excited states are derived. Ferromagnetic ground and excited state exchange parameters J(GS) = -1.55 cm(-1) and J(ES) = -0.53 cm(-1) are determined, respectively, and the relevant orbital contributions to the net exchange are derived from the spectra. The results are compared with those reported earlier for the structurally and electronically analogous [Mn(2)X(9)](5-) pairs in CsMgX(3):Mn(2+) (X = Cl(-), Br(-)), in which the splittings are antiferromagnetic. This major difference is found to be due to the increased metal charge of Fe(3+) compared to Mn(2+), leading to orbital contraction and thus to a strong decrease of the orbital overlaps and hence the antiferromagnetic interactions.

Exchange pathways in tris-mu-thiolato-bridged [Cr(2)L(3)](ClO(4)2Cl*H2O*MeOH (L=2,6-bis(aminomethyl)-4-tert-butyl-thiophenolate).

From polarized optical absorption and emission spectra of the tris-mu-thiolato bridged [Cr(2)L(3)](ClO(4))(2)Cl.H(2)O.MeOH (L = 2,6-bis(aminomethyl)-4-tert-butyl-thiophenolate) 1 in the visible and near UV, the exchange splittings of the (4)A(2) ground and the (2)E and (2)T(1) excited states are determined. In view of the large Cr-Cr distance of 3.01 A, the antiferromagnetic ground state splitting with J = 78 cm(-1) (H = J(S(A).S(B))) is large compared to other triply bridged Cr(3+) dimers. This can be rationalized using a model based on a valence bond approach, in which the exchange splittings are derived from configuration interactions between the ground electron configuration and ligand-to-metal (LMCT) as well as metal-to-metal (MMCT) charge-transfer configurations. It allows us to distinguish the interactions via ligand orbitals from the direct interactions between the metal-centered orbitals. We compare our results with those obtained for the tri-mu-hydroxo-bridged [Cr(2)(OH)(3)(tmtame)(2)](NO(3))(3) (tmtame = N,N',N' '-trimethyl-1,1,1-tris(aminomethyl)ethane) 2. In the latter the interactions via the ligands are negligible, whereas they play an important role in 1, due to the softness of the sulfur ligand atoms.

Optical dimer excitations and exchange parameters in (Et4N)3Cr2F9: first observation of the 4A2 --> 2A1 transition.

The synthesis, crystal growth, and polarized optical absorption spectra in the visible and near-UV of (Et4N)3Cr2F9 are reported. In the energy range 25800-27700 cm(-1) the 4A2 --> 2A1 (O notation) ligand field transition can be resolved in detail for the first time in any Cr3+ compound. This allows the determination of the antiferromagnetic ground-state exchange splitting with great accuracy: J = 25.9 cm(-1) and j = 0.27 cm(-1) using the Hamiltonian H = J(S(A).S(B)) - j(S(A).S(B))2, where j leads to deviations from the regular Landé pattern. The temperature dependence of the magnetic susceptibility is nicely reproduced by these parameters. A comparison with Cs3Cr2Cl9 and Cs3Cr2Br9 reveals an exponential dependence of the ground-state splitting upon the Cr-Cr distance in the [Cr2X9]3- dimers. This is the result of a dominant sigma-type orbital exchange pathway along the Cr-Cr axis.

Control of fleas on dogs and cats and in homes with the combination of oral lufenuron and nitenpyram.

Efficacy of lufenuron (Program, Novartis Animal Health, Greensboro, NC), an insect growth regulator, and nitenpyram (Capstar, Novartis Animal Health), an insecticide for reducing flea populations, was evaluated in 35 flea-infested dogs and cats residing in 18 households in Tampa, Florida. Pets were randomly allocated by household to two treatment groups. Pets in both treatment groups were given lufenuron orally according to label directions on Day 0, then once a month for 3 months. Pets in one group were also given nitenpyram tablets by the owner orally once a day every other day. Pets in the second group were given nitenpyram by their owners as needed but no more frequently than once daily. Flea numbers on pets and in homes were assessed throughout the study by the use of visual body area counts and intermittent-light traps, respectively. The combination of lufenuron and nitenpyram reduced flea populations on pets by at least 97.3% within 7 days and maintained this rate of reduction in flea numbers for the duration of the study, regardless of which regimen was used for administering nitenpyram. For either group, premise flea counts were reduced by up to 89.5% by Day 28 and by as much as 100% by Days 84 to 90.

Effects of a new insect growth regulator, CGA-255'728, on the different stages of the cat flea (Siphonaptera: Pulicidae).

A new juvenile hormone mimic CCA-255'728, developed by Novartis, was tested for its efficacy on different life stages of the cat flea, Ctenocephalides felis (Bouché). The compound was mixed in bovine blood at concentrations of 1, 10, and 100 ppb and fed to adult fleas using an artificial membrane system. Less than 7% of the eggs from fleas fed 10 and 100 ppb hatched, compared with >70% hatch in eggs laid by control fleas or fleas fed 1 ppb. Histological studies demonstrated that approximately 50% of the eggs from fleas fed 10 ppb contained unhatched larvae that died after completing embryological development. At 100 ppb, 24% of the fleas died as fully formed larvae within the egg, but at this concentration nearly 20% of fleas also died before embryogenesis was completed. In addition to embryonic and larval mortality, approximately 28% of eggs from the 100 ppb-treated group were deposited as empty shells. Evidently these eggs were crushed by the muscular action of the oviduct and yolk was expelled into the oviduct during oviposition. None of the test concentrations showed adulticidal effects over a 10-d period. Fecundity was significantly increased with increased concentrations of CGA-255'728 indicating that the compound mimicked the effect of juvenile hormone.

Mode of action of lufenuron in adult Ctenocephalides felis (Siphonaptera: Pulicidae).

When cat fleas, Ctenocephalides felis (Bouché), were fed concentrations of lufenuron in cattle blood ranging from 0.5 to 4 ppm, adult mortality increased in a dose-dependent manner to a maximum of approximately 24% over a period of 10 d. Fleas treated with 0.5 ppm produced abnormal endocuticle consisting of protein globules embedded in an amorphous chitin matrix. At concentrations of 1.0 ppm or greater, endocuticle formation was inhibited. Ultrastructural studies demonstrated that inhibition of chitin synthesis was associated with degeneration of the epidermal cells. The amount of epidermal cytoplasm decreased and cytoplasmic organelles including mitochondria, ribosomes, and golgi showed lytic changes. At least some mortality of treated fleas was likely the result of a weakened endocuticle and the corresponding decrease in resiliency of the cuticle to expansion during blood-feeding and egg production. An unexpected result of lufenuron treatment was the inhibition of midgut epithelial cell differentiation. At concentrations of 0.5 and 1.0 ppm, partially differentiated epithelial cells were seen in the midgut of bloodfed fleas along with fully differentiated cells.

Effect of lufenuron on chorionic and cuticular structure of unhatched larval Ctenocephalides felis (Siphonaptera: Pulicidae).

When adult cat fleas, Ctenocephalides felis (Bouché), were fed concentrations of < or = 0.08 ppm lufenuron in cattle blood, egg hatch did not differ significantly from the controls. However, as the concentration of lufenuron in blood increased from 0.125 to 1.0 ppm egg hatch decreased to 64 and 2%, respectively. Most of these eggs contained fully developed larvae. Microscopic examination of unhatched larvae, revealed that the cuticle epidermal cells, chorion, and vitelline membrane all were affected by lufenuron treatment. Larvae often produced 2 separate cuticles in response to treatment. The 1st cuticle consisted of an indistinct layer of epicuticle and a procuticle composed of randomly deposited chitin microfibrils. After the 1st layer of procuticle separated from the epidermal cells, a 2nd layer of procuticle was deposited. It was not possible to determine whether the egg tooth was functional during larval hatch. The surface of the egg tooth appeared normal, but the cuticle may have had structural abnormalities similar to those seen in other areas of the exoskeleton. Structural defects appeared to be due to the cytotoxic effects of lufenuron. The epidermal cells of treated larvae showed evidence of disintegration (i.e., the nuclei and mitochondria appeared to be degenerating and the amount of endoplasmic reticulum and other cytoplasmic organelles was decreased). The chorion of lufenuron-treated larvae consisted of an outer layer, middle and inner layers that were thinner and less electron dense than those of controls, and lacked the innermost chorionic layer found in the control larvae. The vitelline membrane also was thinner than that of the controls. Larval hatching was prevented by ruptures in the cuticle, which opened during eclosion resulting in the loss of hemolymph and desiccation of the larva. Evidently, tearing of the cuticle was caused by abnormal formation of the procuticle that was not strong enough to withstand the cuticular expansion and muscular movement of the larva within the egg shell.