Oral treatment of rodents with fipronil for feed-through and systemic control of sand flies (Diptera: Psychodidae).

The sand fly Phlebotomus papatasi Scopoli is the vector of Leishmania major (Yakimoff & Schokhor), which is maintained in populations of burrowing rodents. The purpose of this study was to conduct a laboratory study to determine the efficacy of oral treatment of rodents with fipronil for control of sand flies that feed on rodent feces as larvae or on rodent blood as adults. We determined through larval bioassays that fipronil was eliminated in feces of orally-treated hamsters at a level that was significantly toxic to sand fly larvae for 21 d after the hamsters had been withdrawn from a fipronil-treated diet. Through bloodfeeding bioassays, we also found that fipronil was present in the peripheral blood of hamsters at a concentration that was significantly toxic to bloodfeeding adult female sand flies for 49 d after the hamsters had been withdrawn from their treated diet. The results of this study suggest that fipronil acts as well as or better than feed-through or systemic insecticides that previously have been measured against sand flies, and is particularly promising because this single compound acts against both larvae and bloodfeeding adults. An area-wide approach using rodent baits containing a fipronil could suppress vector populations that originate in the vicinity of rodent reservoirs, and could be used to eliminate the most epidemiologically important part of the vector population: female sand flies that take bloodmeals on rodent reservoirs.

Laboratory evaluation of rubidium as a long-lasting marker for bloodfeeding sand flies (Diptera: Psychodidae).

The objective of this study was to evaluate the use of the trace element rubidium (Rb) as a long-lasting systemic biomarker for bloodfeeding females of the sand fly Phlebotomus papatasi Scopoli. Baits containing Rb chloride were found to be palatable to hamsters in this study. We were able to detect Rb using a portable X-ray fluorescence analyzer in all sand flies that fed on Rb-treated hamsters for at least 14 d postbloodmeal. We also detected Rb in sand flies that took a bloodmeal from hamsters up to 10 d after the hamsters were withdrawn from a Rb-treated diet. Results of this study constitute proof of concept for the incorporation of Rb chloride into rodent baits for marking bloodfeeding sand flies, and suggest that Rb marking could be used as a technique for evaluating rodent-targeted sand fly control methods and in ecological studies on sand flies.

Evaluation of three feed-through insecticides using two rodent and two sand fly species as models.

The efficacy of 3 rodent feed-through insecticides (novaluron, pyriproxyfen, and ivermectin) was determined against larvae of the sand flies Phlebotomus duboscqi and P. papatasi using Syrian hamsters (Mesocricetus auratus) and Mongolian gerbils (Meriones unguiculatus) as laboratory models. For each insecticide, there were no significant differences between the longevity or percentage survival of sand fly larvae that had been fed feces of treated rodents for each sand fly or rodent species pairing. The results of this study suggest that larvae of P. duboscqi and P. papatasi are equally susceptible to the concentrations of the rodent feed-through insecticides tested in this study and that these insecticides are pharmacologically compatible with different rodent/sand fly interactions.

Comparison of adhesion formation associated with Pro-Tack (US Surgical) versus a new mesh fixation device, Salute (ONUX Medical).

BACKGROUND: We evaluated efficacy and associated adhesion formation of an innovative mesh fixation device versus the helical tack device and analyzed two implantation techniques. METHODS: Six purpose-bred female hounds were evaluated in this 90-day survival study. Six 4-cm round patches of 1-mm thick DualMesh were fixed to the abdominal wall with either 10 Pro-Tack or 10 Salute constructs in each patch. Zero to 4 additional patches were implanted with only Salute constructs. RESULTS: Adhesion severity scores were significantly higher for middle left abdominal wall sites versus lower right and upper left sites. The adhesion dissection score was higher for group T (Pro-Tack) versus group S (Salute). CONCLUSION: No significant effects occurred with adhesion extent scores, but group T developed denser adhesions. The second analysis determined that no significant differences existed relevant to secondary Salute placement, although the total score approached significance (p < 0.09). Salute equipment was easier to handle and allowed repositioning of the patch during operation.

Changes in seasonal deaths from myocardial infarction.

BACKGROUND: Cardiovascular disease is the major contributor to excess morbidity and mortality in winter. With the rise in temperatures through global warming, and the use of central heating and air conditioning, this seasonal variation may be declining. AIM: To study possible changes in seasonal variation in case-fatality rates of myocardial infarction (MI), in men and women, over a 20-year period and compare this with possible environmental influences. DESIGN: Retrospective analysis of death certificate and climatological data. METHODS: We analysed all monthly death certificate data from Northern Ireland, for death caused by MI from 1979 through 1998 (n=68 683). Mortality data were standardized to a single reference group for the whole period. Seasonal variation in mortality and in environmental variables was described using the cosinor model. RESULTS: A total of 29 875 women and 38 808 men died from MI during the 20-year period. A significant decrease in mortality from MI was observed in both sexes, accompanied by a non-significant decline in the amplitude of the seasonal rhythm over the study period. Low temperature was associated with higher mortality rates from MI. DISCUSSION: We have documented an overall decline in cardiovascular mortality from 1979 to 1998, together with a small but non-significant decrease in seasonal variation. While improvements in medical care, lifestyle, housing and diet may have contributed to the observed decline in mortality rate, seasonal fluctuations remain a significant problem.

Tissue attachment strength of prosthetic meshes used in ventral and incisional hernia repair. A study in the New Zealand White rabbit adhesion model.

BACKGROUND: Many prosthetic materials are used in incisional hernia repair, including polypropylene (PP) and expanded polytetrafluoroethylene (ePTFE). However, PP forms severe adhesions and ePTFE has raised concerns about the adequacy of tissue attachment. METHODS: The early tissue attachment strength of PP and two new forms of ePTFE (DLM and DLMC) was compared in a rabbit model (n = 12) in which disks of the three meshes (n = 8 of each material) were implanted against the abdominal wall for 3 days. RESULTS: Tensiometer testing found that DLMC mesh had significantly greater attachment strength than PP (p = 0.02). Histologic studies indicated that this was due to cellular ingrowth. Tissue adhesions were observed with all eight PP disks, one DLMC disk, and none of the DLM disks. CONCLUSION: Modified forms of ePTFE mesh may provide abdominal wall repairs that are as strong or stronger than those obtained with PP, with early tissue attachment and without adhesions.

Transcutaneous blood gas monitoring in the rat.

Transcutaneous blood gas (TCBG) analysis is a noninvasive alternative method of estimation of blood gas tensions. The objective of the study reported here was to validate this method against standard blood gas (STBG) analysis in adult and juvenile Sprague-Dawley rats. We sought to establish the optimal TCBG probe site and temperature, to establish probe temperatures that would not cause thermal burns, to evaluate correlations between blood gas values (PaCO2 and PaO2) determined by use of TCBG and STBG, and to evaluate the sensitivity of the TCBG unit to changes in arterial blood gas partial pressures. Our results indicated that: in general, the xyphoid area was the optimal site for probe placement, with 44.5 degrees C being the optimal probe temperature for the highest correlation, but thermal burns may be a problem; probe temperatures of 42.5 degrees C (adults) and 42.0 degrees C (juveniles) do not cause thermal burns when left in place for three hours; probe temperatures of 44 degrees C (adults) and 42 degrees C (juveniles) resulted in moderate correlation between PaCO2 and PtcCO2; and the TCBG unit adequately responded to changes in arterial blood gas partial pressures. Neither PtcCO2 or PtcO2 reflect actual values of PaCO2 or PaO2, respectively. We concluded that TCBG analysis may be used as an indicator of change in PaCO2 with sufficient animal numbers under tightly controlled conditions, but not as an indicator of change in PaO2 in adult and juvenile rats.

Common guidelines and equitable service: variation between adjacent districts regarding admissions to elderly care institutions.

With the increasing number of older people, the cost of providing institutional care has become a major issue. In 1993 the introduction of care management and a needs-led approach aimed to remove the existing 'perverse incentive' to institutional care and to ensure equality in the dependency levels of those who were admitted to care. To test this consistency, we examined the dependency levels of all persons aged > or = 65 years admitted to residential and nursing homes in two adjacent Health and Social Services (HSS) Community Trusts in Belfast, Northern Ireland, in the year following the introduction of care management. We measured differences between the Trusts with respect to number of admissions, levels of dependency as determined by several standard scoring systems, financial support, source of admission and demographic information. A total of 389 people were surveyed. Trust A had significantly higher levels of physical dependency and mental impairment in both residential and nursing homes than Trust B. We also identified differences in dependency with respect to funding status, with those who were self-funding in Trust B having lower physical dependency in residential and nursing homes and less mental impairment in nursing homes than supplemented residents. This study reports the existence of variations between adjacent Community Trusts operating under the same policy guidelines with respect to the dependency levels of admissions to residential and nursing care. These differences may relate to number of places available, the economic status of the population, and the assessment procedures of the two Community Trusts. The need for standard assessment and eligibility criteria is highlighted.

The relationship between elevated fibrinogen and markers of infection: a comparison of seasonal cycles.

To test the hypothesis that higher levels of fibrinogen in winter are related to infections via the acute phase response, we assessed seasonal variation in fibrinogen and C-reactive protein, together with three other responses to infection: white cell count, human herpesvirus-6 IgG antibody and interleukin-6. Monthly blood samples from 24 subjects aged 75+ years were assessed for fibrinogen, C-reactive protein, white cell count, and human herpesvirus-6 IgG antibody. Interleukin-6 was measured in seven. Seasonal variation of these measures was determined by the population-mean cosinor procedure. Fibrinogen had a significant seasonal variation with a winter peak (mid-February) 1.26 g/l above the corresponding summer trough. C-reactive protein had a late-February peak, 3.71 mg/l above the summer trough. No seasonal rhythm was found in any other response to infection investigated. This study provides no evidence that winter infections are responsible for the seasonal variation in fibrinogen or C-reactive protein. The explanation for the seasonal changes in these proteins remains unknown.

Effect of tourniquet pressure and intra-individual variability on plasma fibrinogen, platelet P-selectin and monocyte tissue factor.

Small differences in levels of certain haemostatic components may be clinically significant. It is important therefore to eliminate potential sources of confounding variability. This study investigated the effect of removing tourniquet pressure prior to sample collection on plasma fibrinogen levels, platelet P-selectin and monocyte tissue factor expression. Blood was collected from the right arm under maintained tourniquet pressure and from the left arm following the release of pressure once the vein was sufficiently inflated for insertion of a needle. Whole blood was labelled within one hour of venepuncture to allow analysis of platelet P-selectin and monocyte tissue factor by flow cytometry. Plasma fibrinogen levels were analysed in samples stored at -70 degrees C, for all individuals at the end of the study using a method based on the Clauss technique. Intra-individual variability for each of the components was assessed by collecting samples under tourniquet pressure from four individuals on the same day on three consecutive weeks. Intra-individual variations were greater than assay CVs for all three components. There were no significant differences between the two tourniquet methods of collection for fibrinogen, P-selectin or tissue factor. In conclusion, there is no reason not to use a tourniquet during collection of blood for analysis of plasma fibrinogen, platelet P-selectin or monocyte tissue factor.

Acute clinical disease in cats following infection with a pathogenic strain of Bartonella henselae (LSU16).

Bartonella henselae is the causative agent of human cat scratch disease as well as several serious sequelae of infections, including bacillary angiomatosis and bacillary peliosis. Conflicting reports describe the pathogenesis of B. henselae in the cat. In this study, we characterized a strain of B. henselae termed LSU16. This strain was isolated on rabbit blood agar from a naturally infected 10-month-old female cat during a recurrent episode of bacteremia. The bacterial species was confirmed by PCR-restriction fragment length polymorphism analysis. Nine cats were infected intradermally with 5 x 10(7) CFU of LSU16, and clinical signs, antibody responses, and bacteremia were monitored. All nine cats developed raised, erythematous areas at the site of inoculation within 72 h postinoculation; the swelling peaked at 14 days postinfection and was not palpable by 28 days postinfection. Fever developed in all nine cats between 6 and 16 days postinfection and lasted for 1 to 8 days. Between 6 and 16 days postinfection, all nine cats experienced lethargy which persisted 5 to 18 days. Seven of nine cats were bacteremic by day 7, and all nine cats had become bacteremic by 14 days postinfection. Bacteremia peaked at 14 to 28 days postinfection in all cats. In six of the nine infected cats, bacterial numbers reached nondetectable levels during the 7th week postinfection; however, a single animal maintained bacteremia to 18 weeks postinfection. All nine cats developed strong antibody responses to B. henselae, as determined by Western blot analysis and enzyme-linked immunosorbent assay. Subsequently, three naive cats were injected intradermally with blood from cats infected with LSU16 from a pure culture, and five naive cats were injected with feces from fleas which had been feeding on cats infected with a pure culture of LSU16. These cats developed signs similar to those described in the previous experiment and were euthanized at 5 weeks postinfection. We conclude that B. henselae LSU16 is a virulent strain of B. henselae in cats and propose that the virulence of B. henselae in cats is strain dependent.

Prevalence of central autonomic neuropathy in elderly dialysis patients.

BACKGROUND: Autonomic neuropathy is frequently present in dialysis patients. In addition, deterioration of autonomic function occurs with ageing. This study examines the true prevalence of autonomic neuropathy in elderly dialysis patients and questions whether the combination of age and uraemia further increases the chance of dysautonomia being present. METHODS: We compared the results of five different tests (30:15 ratio; Valsalva ratio; heart rate response to deep breathing and the blood pressure responses to sustained hand grip and standing) of parasympathetic and combined parasympathetic and sympathetic dysfunction in older haemodialysis patients (mean age 70.2 years), younger haemodialysis patients (mean age 48.1 years) and two groups of subjects with normal renal function (mean age 73.0 years and 42.5 years respectively). RESULTS: Parasympathetic dysfunction was most prevalent in older patients on dialysis (65.9% (95% confidence intervals 51.4-80.4%), compared with 33.3% (95% confidence intervals 19.0-47.5% in younger dialysis patients), and 11.8 and 0% in the old and young control groups respectively). Combined parasympathetic and sympathetic dysfunction was seen in 41.5% (95% confidence intervals 26.5-56.5%) and 11.9% (95% confidence intervals 2.1-56.5%) of the old and young dialysis patients respectively but not in any of the control subjects. No interaction was seen between age and subject type. CONCLUSIONS: We conclude that although older dialysis patients have severe impairment of cardiovascular autonomic innervation, the prevalence of dysfunction is not higher than would be expected in an ageing population with uraemia.

Autonomic function in patients on continuous ambulatory peritoneal dialysis.

OBJECTIVE: To investigate sympathetic function in the peripheries of patients on chronic ambulatory peritoneal dialysis (CAPD) using noninvasive techniques. DESIGN: Comparison of peripheral blood flow responses in sympathetic vasoconstrictor reflexes in CAPD patients and matched control subjects. SETTING: Tertiary care hospital and research institution. PATIENTS: Twenty-three clinically stable CAPD patients and 23 control subjects matched for age, sex, and drug therapy. MAIN OUTCOME MEASURES: Sympathetic activity assessed from the reductions in hand and foot blood flow induced by a deep breath and by body surface cooling. Cardiac autonomic activity measured by the changes in heart rate produced by deep breathing, a Valsalva maneuver, and standing from lying. RESULTS: A deep breath induced mean decreases in hand blood flow of 65.1% in the patients and 82.8% in their matched controls. Corresponding reductions in the foot were 46.0% and 70.0%. Body surface cooling reduced mean hand blood flow by 50.3% in the patients and 71.8% in the control subjects. Corresponding values in the foot were 26.7% and 43.6%. The differences in response between the patients and their matched control subjects were all significant (p < 0.01). Cardiac autonomic function assessed by standard tests of heart rate variability was significantly impaired in the patients compared with the control subjects in two of the three tests used (p < 0.001). CONCLUSIONS: Cardiovascular autonomic impairment can affect the peripheral circulation as well as the heart in patients on dialysis, and this may have implications for cardiovascular homeostasis.

Autonomic neuropathy predisposing to arrhythmias in hemodialysis patients.

Arrhythmias are frequent among the dialysis population and can cause symptoms of palpitations or dizziness. Since autonomic disturbances are known to cause an increased arrhythmogenic stimulus, we questioned whether the presence of central autonomic neuropathy increased the frequency of arrhythmias as identified by 24-hour electrocardiographic monitoring in dialysis patients. Seventy-one patients were randomly chosen from patients established on dialysis in two centers. The mean age of the patients was 71.3 years (median age, 67 years) and median duration on dialysis was 17.0 months (range, 1 to 175 months). Four patients had diabetes. Each patient was tested for autonomic control of blood pressure and heart rate, and underwent Holter electrocardiographic monitoring, commencing 30 minutes before dialysis, for a 24-hour period. The tapes were then analyzed for ventricular and atrial rhythm changes. There was a significantly increased incidence of arrhythmias in individuals with abnormal blood pressure responses (P = 0.005), heart rate responses (P = 0.01), and combined blood pressure and heart rate responses (P = 0.004). We conclude that patients with autonomic dysfunction had an increased frequency of arrhythmias during dialysis.