Effect of Wuchereria bancrofti (Cobbold infection on the biological activities of Culex pipiens L. (Diptera: Culicidae) in Egypt

The impact of moderate infection with Wuchereria bancrofti (Cobbold) (25 mf/50 microliters blood) on the biological activities of Culex pipiens L. were investigated. Data revealed that W. bancrofti parasites did not interfere significantly with the oviposition rate (81.97%, 80.228% in non-infected and infected mosquitoes, respectively), fecundity (73.56 +/- 4.56 and 74.23 +/- 5.05 eggs/female) duration of the gonotrophic cycle (6.34 +/- 0.29 and 6.05 +/- 0.26 days), or egg hatchability (88.06% and 90.07%) of infected mosquitoes. Furthermore adult survival to the extrinsic incubation period of infected females (91.8%), did not vary from that of non-infected ones (78.87%). It is suggested that the lack of variations is due to the relatively low level of microfilariae (mf) to which mosquitoes are generally exposed, as revealed by parasite burden. It is concluded that in Egypt the relationship of W. bancrofti to Cx. pipiens is that of a commensal rather than a parasite.     

Changes in selected aspects of immune function in the leopard frog, Rana pipiens, associated with exposure to cold

The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte populations, and serum complement levels was examined in the northern leopard frog, Rana pipiens. Proliferation of T lymphocytes in response to phytohemagglutinin stimulation was significantly decreased in frogs kept for 2, 3, and 5 months at 5 degrees C compared to that of animals kept at 22 degrees C. A significant increase in the average percentage of neutrophils and a decrease in the mean percentage of eosinophils was observed in the blood of frogs held for 5 months in the cold compared to animals held at 22 degrees C for the same length of time. Mean serum complement activity after 1 month at 5 degrees C was significantly reduced in comparison to animals held at 22 degrees C and was not detectable after 5 months in the cold. Recovery of complement levels at room temperature (22 degrees C) was also examined after cold exposure. Complement levels were significantly higher than controls (at 22 degrees C) in frogs returned to 22 degrees C for 7 and 14 days after 5 months in the cold. After frogs were held at 5 degrees C for 1 month, serum complement levels increased significantly within 2 days after returning to 22 degrees C and continued to rise 5 and 9 days after warming. Injections with Aeromonas hydrophila following a 5-week exposure to 5 degrees C failed to cause death or observable symptoms of disease in frogs that were returned to 22 degrees C.     

Effect of the developmental stage at infection on the ability of adult Anopheles stephensi to transmit Rift Valley fever virus

The ability of adult Anopheles stephensi to transmit Rift Valley fever virus was determined for mosquitoes inoculated at selected times during development. None of 109 female An. stephensi inoculated as adults transmitted virus to hamsters. In contrast, 83% (50 of 60) of those inoculated as larvae transmitted virus by bite to hamsters. Transmission rates decreased as the stage of the mosquito at the time of inoculation changed from larva to pupa to adult. Transmission rates for adult mosquitoes inoculated as larvae, as pupae < 4 hr after pupation, as pupae > 24 hr after pupation, or as adults were 83%, 25%, 11%, and 0%, respectively. Viral titers recovered from mosquitoes were similar for all groups tested, regardless of stage at infection (larva, pupa, or adult) or of transmission status (transmitter or nontransmitter). Thus, differences in transmission rates may have been due to site-specific (i.e., salivary gland) replication, rather than a generalized increase in viral replication in mosquitoes inoculated at an earlier age.     

Susceptibility to Brugia pahangi of geographical strains of Culex pipiens fatigans

Five strains of Culex pipiens fatigans from Kuala Lumpur, Tanga, Bobo Dioulasso, Ibadan and Maracay were tested for susceptibility to Brugia pahangi. The mosquitoes were membrane-fed on infected blood in which the parasite density ranged from 1-3 to 20-4 mff/mm(3). The susceptibility rates were low, and were not directly related to the parasitaemia. If the susceptible individuals represent homozygotes for the gene sb (the gene controlling susceptibility to B pahangi in C. pipiens), the gene frequencies in the five strains were 0-33, 0-23, 0-28, 0-12 and 0-31 respectively.     

Efficacy of Coxiella burnetii and its chloroform-methanol residue (CMR) fraction against Rift Valley fever virus infection in mice

Strains of Coxiella burnetii phase I and II whole cells (WC-I and WC-II) or whole cell fractions were assessed for their potential to induce long-lasting protection in endotoxin-non-responder C3H/HeJ or CD-1 mice against Rift Valley fever (RVF) virus challenge. Among the whole cell fractions, only the chloroform-methanol residue (CMR), administered as a single dose (100 micrograms per mouse) 24 h before viral challenge, effectively protected 100% of the mice from RVF virus; the CMR of the Ohio strain of C. burnetii was not protective. Most of the RVF virus-infected mice treated with other C. burnetii cell fractions died, although their times to death varied. Lipopolysaccharide (LPS) associated with CMR preparations used in these studies, did not protect against RVF virus challenge. A single dose of 100 micrograms of CMR given 24 h before viral challenge completely eradicated 4-5 logs of RVF virus in the serum, liver, spleen, and central nervous system. Compared to several other immunomodulators, CMR was an equally effective antiviral agent. Efficacy of CMR of both Henzerling and Ohio strains disappeared or was marginal when treatment was initiated 2-3 days before RVF viral challenge, even when a second or a third dose of CMR was administered after challenge. A single dose of liposome-encapsulated CMR to RVF virus-infected mice extended the range of therapeutic efficacy of this biologically active component of C. burnetii to 4 days before infection.     

Ovarian development and parity determination in Culiseta melanura (Diptera: Culicidae)

Eastern equine encephalomyelitis virus (EEE) is perpetuated in a maintenance cycle that involves Culiseta melanura (Coquillett) as the enzootic vector and passerine birds as the amplifying hosts. Amplification of virus in any given year requires an influx of nulliparous Cs. melanura in the presence of susceptible avian hosts. We conducted laboratory experiments at constant temperatures from 10 to 34 degrees C to develop thermal heat summation models to predict emergence in nature. Embryonic development progresses slowly at 10 degrees C, and the time to eclosion decreased significantly as temperatures increased to 28 degrees C. High temperature were lethal and eggs failed to hatch at 32 degrees C. The thermal minimum (t0) for embryonic development was 9.38 degrees C, and 38.46 degrees-days (DD) were required for egg hatch. The time for larval development decreased with increasing temperatures. Cs. melanura larvae develop in subterranean habitats (crypts) where water temperatures remain below 20 degrees C throughout the summer. Under controlled conditions, egg hatch to emergence took 8 mo at 10 degrees C, 3 mo at 16 degrees C, and 1 mo at 22 degrees C. The thermal minimum for larval development (t0) was 8.5 degrees C, and 467.29 DD were required from eclosion to adult emergence. Our findings indicate that Cs. melanura is well suited to develop in cold water crypts where the larvae are collected most frequently. The mosquito appears to be bivoltine in the northeast with an overwintering generation of larvae that emerges as a spring brood of adults and a summer generation of larvae that emerges in fall. Higher than normal water temperatures hasten development of the summer generation and increase the probability for amplification of EEE by bringing large numbers of nulliparous mosquitoes into contact with recrudescing virus for subsequent transfer to the growing population of susceptible juveniles. Water temperatures in the crypts also may regulate the northern limit for virus amplification each year.     

Histological features of respiratory epithelium of calves held at differing temperature and humidity

The effect of ambient temperature and humidity on the structure of respiratory epithelium of calves was studied. Four calves of each of three experiments were acclimatized to a nonoperational environmental chamber for six days and then exposed to constant extremes of temperatures and relative humidity of one of 30 degrees C --35%, or 27 degrees C--92%, or 5 degrees C--92% respectively in this chamber for eight days each. Five calves (3 and 2) were similarly acclimatized then exposed to 1 degrees C--40%. Nasal swabs were taken from all animals at regular intervals. Swabs of three animals yielded Mycoplasma spp. and one swab yielded the virus of infectious bovine rhinotracheitis. Detailed histological studies of respiratory epithelium of nose, trachea, major bronchus and terminal bronchioli were conducted at four sites. Goblet cells were least in calves held in hot and dry air; calves held in dry air had the least polymorphonuclear cells and the greatest prevalence of hypochromatic cell layers and vacuolation of epithelial cells. Differences between experiments were evident most for sites of trachea and major bronchus.     

West Nile encephalitis epidemic in southeastern Romania

BACKGROUND: West Nile fever (WNF) is a mosquito-borne flavivirus infection endemic in Africa and Asia. In 1996, the first major WNF epidemic in Europe occurred in Romania, with a high rate of neurological infections. We investigated the epidemic to characterise transmission patterns in this novel setting and to determine its origin. METHODS: Hospital-based surveillance identified patients admitted with acute aseptic meningitis and encephalitis in 40 Romanian districts, including Bucharest. Infection was confirmed with IgM capture and indirect IgG ELISAs. In October, 1996, we surveyed outpatients in Bucharest and seven other districts to estimate seroprevalence and to detect infected patients not admitted to hospital. We also measured the rates of infection and seropositivity in mosquitoes and birds, respectively. RESULTS: Between July 15 and Oct 12, we identified 393 patients with serologically confirmed or probable WNF infection, of whom 352 had acute central-nervous-system infections. 17 patients older than 50 years died. Fatality/case ratio and disease incidence increased with age. The outbreak was confined to 14 districts in the lower Danube valley and Bucharest (attack rate 12.4/100000 people) with a seroprevalence of 4.1%. The number of mild cases could not be estimated. WN virus was recovered from Culex pipiens mosquitoes, the most likely vector, and antibodies to WN virus were found in 41% of domestic fowl. INTERPRETATION: The epidemic in Bucharest reflected increased regional WNF transmission in 1996. Epidemics of Cx pipiens-borne WNF could occur in other European cities with conditions conducive to transmission.     

Participation of bdellovibrios in sewage self-purification processes

The participation of bacterial parasites belonging to the genus Bdellovibrio in the processes of sewage self-purification was studied in refineries of Pushchino. The lytic activity of Bdellovibrio resulting in a decrease of the number of heterotrophic Gram-negative bacteria and E. coli in sewage was found to depend on the temperature factor influencing the intensity of interaction between the parasite and the host bacterium. The maximal p/h (parasite/host) index was found at the water temperature of 26 degrees C and the minimal one at 19 degrees C. Sewage purified at 26 degrees C and transferred to a precipitation tank contained 800 cells of E. coli in 1 ml while that purified at 19 degrees C contained 4000 cells in 1 ml. The number of interacting organisms varied in sewage which was typical of the "parasite-host" relations. Therefore, Bdellovibrio should be involved in the self-purification of sewage from the intestinal microflora at 26 degrees C; to a lesser extent, at 23.5 degrees C; and not at all, at 19 degrees C.     

Performance of a hydrophobic heat and moisture exchanger at different ambient temperatures

OBJECTIVE: To evaluate the effect of different room temperatures on hydrophobic heat and moisture exchangers (HME) humidifying capability and efficiency. METHODS: Stock HMEs were tested in vitro using an already described test model, with separation of inspiratory and expiratory gas. Absolute humidity (AH) was measured by means of dry-wet dual thermocouple, and HME efficiency was computed as the ratio between expired to inspired AH, at room temperature of 20 and 26 degrees C. RESULTS: Inspired gas temperature and AH were significantly higher at 26 than at 20 degrees C; since expired AH remained substantially unchanged, HME efficiency was also higher in warmer environment. CONCLUSIONS: Hydrophobic HMEs appear to be affected by room temperature, increasing their humidifying ability and their efficiency with its rise.     

Refractory status epilepticus: response to ketamine

Eight Neisseria meningitidis reference strains, representing six different serogroups, were plated on 57 blood agar plates each. The growth was harvested and stored in silica gel packages at different temperatures for up to 90 days. When held at 4 degrees C, all strains were recovered after 90 days of storage. Strains held at room temperature or alternately at 4 degrees C and room temperature survived for at least 10 and 17 days, respectively.     

The vitamin B 6 requirements of the laying hen for reproduction

Some parameters related to withstanding severe cold (-20 degrees C) after administration of increasing doses of ethanol were investigated using guinea-pigs. The animals had been reared either at 22-23 degrees C or at 17-18 degrees C. They received ethanol in doses of 0.8 g, 1.2 g, 1.4 g or 1.6 g per kg of body weight. The fall of rectal temperature and its level at death were registered. The survival time, ethanol concentration in the blood and the brain, serum glucose and serum FFA at death were determined. In the animals reared at 22-23 degrees C the ethanol doses of 1.2-1.6 g/kg caused a significant shortening of the survival time and accelerated the fall of the rectal temperature. In addition the rectal temperature at death after ethanol was lower than in the controls. In the animals reared at 17-18 degrees C the ethanol doses used did not have any significant effect on the survival time and the rectal temperature. In both groups, ethanol concentration in the brain was lower (about 20-40%) than in the blood, the difference being greater in the group reared at 22-23 degrees C. Ethanol had no effect on the glucose concentrations. Serum FFA levels were slightly lower in animals reared at 22-23 degrees C than in those grown in the cooler temperature. It became evident that ethanol has a dose dependent deleterious effect on the thermoregulation of animals reared in warm (22-23 degrees C). The effect was seen at and above the dose of 1.2 g/kg. The results indicate further even a slight acclimation to cold was able to abolish the effect of these rather great doses of ethanol in severe cold exposure.     

Role of Anopheles quadrimaculatus and Coquillettidia perturbans (Diptera: Culicidae) in the transmission cycle of Cache Valley virus (Bunyaviridae: Bunyavirus) in the midwest, USA

Midwestern populations of Coquillettidia perturbans (Walker) and Anopheles quadrimaculatus (Say) were tested for their ability to transmit Cache Valley virus (CV), a recognized human and animal pathogen. Field-collected mosquitoes were fed artificial blood meals containing 5.2-6.2 log10 pfu/ml of CV. After 9-23 d at 28 degrees C, 75-93% of blood-fed Cq. perturbans had disseminated infections and 6-62% transmitted the virus to suckling mice. However, when infected with a lower virus titer (3.3 log10 pfu/ml), only 10-36% of the mosquitoes had disseminated infections and 0-10% transmitted the virus to suckling mice. A similar infection rate (21%) was observed in Cq. perturbans fed on viremic (3.2 log10 pfu/ml) hamsters. An. quadrimaculatus were infected (81-100%) by both doses used, with transmission rates ranging from 13-67% after 16-23 d of incubation. Transmission rates for the laboratory strain An. quadrimaculatus SAVANNAH ranged from 20 to 33% after 7-14 d of incubation. Our data show that although An. quadrimaculatus is more susceptible to CV infections than Cq. perturbans, both mosquito species could be involved in the midwestern transmission cycle of the virus.     

The relationship between insulin bioactivity and structure in the NH2-terminal A-chain helix

Old females are compared to young females for the purpose of studying the difference in comfort caused by the environmental variables of temperature and humidity as well as the form of clothing. Eight experiments were performed in three settings: (a) 30 degrees C R.H.80%; 30 degrees C R.H.45%; and 20 degrees C R.H.45%. The ages of the subjects range from 62 to 68 (Mean = 65.17, S.D. = 1.68) among old females and from 20 to 23 (Mean = 20.83, S.D. = 0.76) among young females. The following results were obtained: (1) The young females were sensitive to hot temperatures, while the old females were not. On the other hand, the old females were more sensitive to cold temperatures, under 20 degrees C R.H.45%, than the young females. In temperatures under 30 degrees C R.H.80%, the heat radiation from the young females was higher than that of the old females. Under 20 degrees C R.H.45%, the heat radiation from the old females was higher than from the young females. The old females are thought to decline in physiogenic function due to enduring both hot and cold temperatures. (2) The correlation between the temperature in clothes and comfort among the old females is not different from the same correlation among the young females. This conclusion agrees with previously published studies of the young females. (3) Skin temperature and bloodstream are measured, according to clothing form. As a result, a long skirt is the highest in thermal insulation, long pants the next highest, and a short skirt is the lowest. (4) The effect of thermal insulation provided by a lap robe was tested in both groups. The lap robe was found to be more effective for the older group than the younger in temperatures under 20 degrees C R.H.45%. Hence, the role of clothes in offsetting for the decline in the thermoregulation function that compensates for environmental change is more important for old females than for young.     

Development of Wuchereria bancrofti in Culex pipiens L. (Diptera: Culicidae) exposed in the larval instar to sublethal dosages of insecticides and one insect growth regulator and their influence on reproduction of filaria-infected mosquitoes

The effects of exposure of Culex pipiens larvae to sublethel concentrations of larvicides on uptake, development of Wuchereria bancrofti, survival rate and reproduction of filaria-infected mosquitoes were investigated. Fourth instar larvae of Cx. pipiens were exposed to LC40 of the surfactant Triton X-100, the insect growth regulator DPX alone or combined with LC10 of the surfactant and permethrin alone or combined with LC10 of the surfactant. Adults that survived insecticide treatments and controls were infected by allowing them to feed on microfilaremic volunteers. Significant reduction in the uptake of microfilaria was observed in groups treated with Triton X-100 alone or combined either with permethrin or DPX when compared to control. The overall infection and infective rates were significantly reduced in mosquitoes treated with Triton X-100 either alone or combined with permethrin. Treatment with Triton X-100 and DPX prolonged the extrinsic incubation period (EIP) and retarded the development of filarial larvae, while permethrin either alone or combined with Triton X-100 and DPX combined with Triton X-100 shortened the EIP. All larvicides reduced the number of infective larvae (L3)/mosquito and induced deformities among he different parasite stages, especially in mosquitoes treated with combination of permethrin and Triton X-100 or mixture of DPX and Triton X-100 where 36% and 54.9% respectively of L3S were deformed. In treated mosquitoes, a low percentage of L3S was detected in the head and proboscis region while the majority was trapped in the thoracic region. The survival rates of mosquitoes were reduced in cases treated with permethrin, DPX and Triton X-100 while treatment with mixture of DPX and Triton X-100 induced higher rate of mortalities when compared to control. Egg production of filaria- infected Cx. pipiens was significantly reduced in mosquitoes treated with DPX and Triton X-100. It was observed that the addition of Triton X-100 to DPX or to permethrin significantly reduced egg production. The results suggest that sublethal concentrations of larvicides especially Triton X-100 applied to 4th instar larvae of Cx. pipiens could effectively interfere with the development of W. bancrofti in Cx. pipiens and reduced the survival rate and fecundity of the vector.     

Investigation of the effect of the cooling mode on the quality of alumina-containing cakes

It has been established under laboratory conditions that there is an increase in the β-C₂S content and a decrease in the α′-C₂S content when the nepheline cake is held for τ = 0–30 min in a temperature range of 630–680°C. Specifically, industrial tests on a fire grate cooler confirmed the effect that the duration of holding the cake at T = 630–680°C exerts on its quality; an increase in τ from 1.6 to 4.9 min led to an increase in the β-C₂S content by 3% and an increase in the α′-C₂S content by 4%.     

Attraction to larval pheromones in female convict cichlids (Cichlasoma nigrofasciatum).

In a choice between an effluent that had bathed filial prolarvae or postlarvae and an effluent of blank tank water, maternal convict cichlids (Cichlasoma nigrofasciatum) preferred the effluent that had bathed their young. Larval pheromones from prolarvae or postlarvae (up to 17 days after hatching) were equally attractive to their mothers. Nonmaternal females were aroused by but were not attracted to conspecific larval pheromones. Physiological age in C. nigrofasciatum fry was altered by body temperature. Hatching of eggs and metamorphosis into postlarvae occurred earlier for brood portions raised in warmer water and later for those raised in cooler water. Mothers preferred the pheromone from delayed-familiar brood portions to that from advanced-unfamiliar brood portions. This preference is consistent with the hypothesis that the larval pheromone changes as the fry develop. Results corroborate previous findings in which researchers presented whole fry as stimuli and found support for the hypothesis that cichlid parents learn to recognize their young. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral thermoregulation in the squirrel monkey when response effort is varied.

Three adult male squirrel monkeys controlled the air temperature within their test chamber by pulling a chain to select between 2 preset air temperatures, 10 and 50Deg.C. When the force required to pull the chain was increased in steps from 2.94 to 6.86 N, interresponse interval increased, resulting in wider air temperature swings within the chamber. The average air temperature selected became progressively lower, producing a concomitant fall in skin temperature. However, internal body temperatures (rectal and brainstem) remained nearly constant due to a compensatory increase in metabolic heat production. By allowing a cooler, rather than warmer, environment to result from a decreased response rate, Ss guarded against hyperthermia, which they were ill equipped to handle autonomically. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infusion of hot crystalloid during operative burn wound debridement

BACKGROUND: Hypothermia exacerbates coagulopathy and is thus a potentially devastating morbidity during operative debridement of burn wounds. Current techniques for maintaining body temperature include warming intravenous fluids at 38 degrees C. The purpose of this study was to assess the safety of infusing saline heated to 55-60 degrees C. METHODS: Using a modified fluid warmer, saline heated to 60 degrees C was infused through central venous access in eight adult patients undergoing debridement of burn wounds. The temperature of the saline actually entering the patient was measured by a thermocouple attached at the connection to the central line catheter. RESULTS: The actual infusate temperature was 54.0 +/- 1.2 degrees C. Over the first hour, 1,100 mL of hot saline was given, thus delivering 17.6 kcal more heat than fluid warmed to the traditional 38 degrees C. Core temperature measured via esophageal and Foley catheters had an insignificant trend toward increase during the operative procedure. There was no evidence of intravascular hemolysis or coagulopathy. CONCLUSION: This pilot study suggests that infusion of hot crystalloids given via central venous access is safe and may be an acceptable adjuvant in attenuating hypothermia during operative procedures.