Growth rate and trapping efficacy of nematode-trapping fungi under constant and fluctuating temperatures

The effect of temperature on radial growth and predatory activity of different isolates of nematode-trapping fungi was assessed. Four isolates of Duddingtonia flagrans and one isolate of Arthrobotrys oligospora were inoculated on petri dishes containing either corn-meal agar (CMA) or faecal agar and then incubated for 14 days under three different constant and fluctuating temperature regimes. The radial growth was similar on the two substrates at each temperature regime. All fungal isolates showed a higher growth rate at a constant 20 °C. At 10° and 15 °C, all D. flagrans isolates showed very similar patterns of radial growth at both constant and fluctuating temperatures. At 20 °C, they grew significantly faster at constant than at fluctuating temperatures. A. oligospora grew significantly faster than all D. flagrans isolates except when incubated at a fluctuating 20 °C. Spores of each fungal isolate were added to faecal cultures containing eggs of Cooperia oncophora at a concentration of 6250 spores/g faeces. The cultures were incubated for 14 days at the same temperature regimes described above. Control faeces (without fungal material) were also cultured. More larvae were recovered from the fungus-treated cultures incubated at a constant 10° or 15 °C than from those incubated at the respective fluctuating temperatures, except for one D. flagrans isolate. Incubation at 20 °C showed the opposite effect. The general reduction observed in the number of nematode larvae due to fungal trapping was 18–25% and 48–80% for a constant and fluctuating 10 °C, 70–96% and 93–95% for a constant and fluctuating 15 °C, and 63–98% and 0–25% for a constant and fluctuating 20 °C, respectively. Received: 15 December 1998 / Accepted: 16 February 1999     

Effect of extreme temperature on egg development,larval and adult survival of <Emphasis Type="Italic">Chordodes nobilii</Emphasis> Camerano, 1901 (Gordiida,Nematomorpha)

On the basis of experimental studies we analyzed the effect of extreme temperatures on the aquatic free-living phases of the life cycle of Chordodes nobilii (Gordiida, Nematomorpha). Bioassays were performed with eggs, larvae, and adults. Eggs and larvae were exposed to 3°C below zero and 40.5°C; adults were exposed to 3°C below zero and to 38.5°C and 40.5°C. The results showed that egg development was inhibited in both tests. Exposed larvae showed a decrease in their infective capacity, which resulted almost null at 40.5°C. Adults exposed to 38.5°C showed mortality ≤10%, at 40.5°C the mortality was 100% and the adult’s mortality at 3°C below zero was 89%. Results indicate that free living stages of Chordodes nobilii are susceptible to extreme temperatures.     

Effects of rearing temperature on hematological and biochemical parameters of great sturgeon (Huso huso Linnaeus, 1758) juvenile

The effect of environmental temperature changes on hematological and biochemical parameters of Huso huso juveniles was studied. Six-month-old juveniles with mean body weight of 69.2 ± 4.1 g were subjected to different temperatures (9–14°C, 15–20°C, and 21–26°C, respectively). The hematological parameters, ion Ca2+, glucose, and the cortisol concentrations were assessed after a period of 21 days rearing at these temperatures. The results show that hematocrit, Ca²⁺, and eosinophil were affected by different temperatures. Increasing temperature led to a significant increase (P < 0.05) in the hematocrit, Ca²⁺, and eosinophil, but white blood cell count, lymphocyte, cortisol, and glucose concentrations were decreased slightly (P > 0.05). The rest of the parameters showed no significant effect with increase in environmental temperature (P > 0.05). These data show significant effect of temperature on the blood parameters of great sturgeon.     

In vitro viability test for the eggs of <Emphasis Type="Italic">Echinococcus granulosus</Emphasis>: a rapid method

In this study an attempt was made to develop an efficient, rapid, simple, and reproducible method for the in vitro viability test of Echinococcus granulosus eggs. The eggs were obtained from an experimentally infected dog and kept at 4°C until use. To prepare the dead or damaged eggs, the eggs were heated in hot water (69–72°C for 10 min), preserved in 70% ethyl alcohol (16 days) or exposed to direct sunlight (18 h). Sodium hypochlorite (0.5–0.7%) was used for the hatching process, and the hatched oncospheres were stained with 0.1% eosin for the viability test. With 0.5% sodium hypochlorite, the hatching rates for viable eggs and eggs killed or damaged by heat (69°C), 70% ethyl alcohol, and direct sunlight were 96%, 97.5%, 91.5%, and 94.6% respectively and there was no significant difference between the hatching rate for viable and dead or damaged eggs (p > 0.05). After staining with 0.1% eosin, the rates of the viable oncospheres hatched from viable eggs and the eggs killed or damaged by heat (69°C), 70% ethyl alcohol, and direct sunlight were 97.5% 3.6%, 7%, and 10.5%, respectively. The difference between the rates of viable oncospheres hatched from viable and dead or damaged eggs was extremely significant (P < 0.0001). With 0.7% sodium hypochlorite, the hatching rates for viable and dead eggs (killed by 72°C for 10 min) were 99.1% and 99.9%, respectively. In this condition, the rate of viable oncospheres was an average of 98.5% for viable eggs and 0.0% for dead ones. The results of this study showed that hatching of eggs by 0.7% sodium hypochlorite and staining of hatched oncospheres by 0.1% eosin are practical methods for the differentiation of viable and nonviable (dead) eggs of Echinococcus granulosus.     

The effect of temperature and host age on the infectivity and development of Angiostrongylus vasorum in the slug Arion lusitanicus

Experimental infection with Angiostrongylus vasorum was conducted in Iberian slugs Arion lusitanicus. Initially, different size/age groups of juvenile slugs (small, <0.5 g and medium, 0.5–1 g) were exposed to freshly isolated first-stage parasitic larvae (L1) of A. vasorum. The slugs were subsequently incubated at 5, 10 and 15°C for 6 weeks. Larval development within the slugs differed significantly with temperature. At 15°C, all larvae developed into the third larval stage (L3), at 10°C into the second stage (L2), whereas no development was observed at 5°C. The mean larval burdens were highest in the largest group of slugs and tended to increase with higher temperature. In a second experiment isolated L1 were incubated at 5, 10 and 15°C for 3 and 7 days prior to infection of slugs, which then were kept for 6 weeks at 15°C. The infectivity decreased significantly with the larval storage time and the mean larval burden per slug was lower at higher incubating temperature. However, all established larvae developed into infective L3. Temperature had an effect on the development of the larvae and thus an impact on transmission of the parasite as only L3 are infective to the definitive canid hosts.     

Temperature Pretreatment Alters the Polarization Response of Human Neutrophils to the Chemoattractant N-formyl-Met-Leu-Phe

Neutrophils present a polarized morphology upon stimulation of chemoattractants, which play a vital role in host-defense mechanisms. Many studies have been published on neutrophil polarization, in which three different temperatures pretreatment (4°C, 25°C and 37°C) have been used. However, no study has investigated whether different temperature pretreatments affect neutrophil polarization. In the current study, we examined the effects of 4°C, 25°C and 37°C pretreatment temperatures on short-term (1 or 3 min) chemoattractant-induced polarization. Human neutrophils were polarized upon the stimulation of N-formyl-Met-Leu-Phe (fMLP) after pretreated by different temperature. The morphological changes of the neutrophils were investigated under the microscopy. The F-actin polymerization was determined by immunological histological chemistry. There were more head–tail polarized cells (>50% of the cells) in the 25°C and 37°C pretreatment groups than in the 4°C group (32.4%). The average lengths of the pseudopod were 3.2 ± 1.1 μm (n = 17), 5.3 ± 2.1 μm (n = 12) and 7.4 ± 2.7 μm (n = 21) in the 4°C, 25°C and 37°C pretreatment groups, respectively; the 4°C and 37°C pretreatment groups were statistically different (P < 0.05). Additionally, there was a statistically significant difference in the pseudopod extension rate among the three groups, as well as the Lamellipod percentage between the 4°C group and the other two groups within 1 min of stimulation with fMLP. This study demonstrates that different temperature pretreatments affect neutrophil polarization upon short-term stimulation with fMLP. Dongliang Zhao, Xiaojing Meng, Chunqing Cai equally contributed to this paper.     

Description and development of the early third-stage larva of Gnathostoma turgidum Stossich, 1902 (Nematoda: Gnathostomatidae) and contributions to its life cycle

The egg and larval stages of Gnathostoma turgidum were examined using light microscopy. Fertilized uterine eggs are 65.97 long and 32.28 wide, oval, brownish, with two cap-like thickenings. The eggshell surface is covered with numerous irregularly shaped pits of various sizes and depths. A sheathed second-stage larva emerges from the egg, measures 178 × 9; the sheath measures 243 × 21. Development to early third-stage larva in the coelomic cavity of cyclopoid copepods is similar to that described for other gnathostome species. After 10 days at 27°C, the larvae undergo a molt (the second for gnathostomes) and develop to early third stage. The body of this stage measures 412.3 × 40.1, with evident hemispherical cephalic bulbs. Cephalic bulbs measure 25 × 40, armed with four transverse rows of sharp hooklets. The average number of hooklets in each row is 31, 34, 37, and 42, respectively. The whole body is covered with 193 transverse rows of small single-pointed cuticular spines. One pair of cervical papillae and an excretory pore are present on the anterior part of the body. On the other hand, potential species-specific features regarding the latter larval stage are discussed. Finally, some G. turgidum life cycle considerations are portrayed.     

Effect of temperature on the development of free-living stages of <Emphasis Type="Italic">Strongyloides ratti</Emphasis>

In the genus Strongyloides, larval development external to the host is known to be markedly affected by a variety of environmental factors. This investigation focuses on the effect of temperature on Strongyloides ratti. Low temperature (15°C) was shown to favor direct development, producing infective larvae, while high temperature (25°C) favored indirect development, producing free-living females and males. Different courses of development were brought about by either a 16-h temperature stimulus at 15°C or a 6-h temperature stimulus at 25°C. Moreover, eggs were not susceptible to the cold-temperature stimulus of 15°C, while newly hatched larvae were. The results indicate that the developmental course of S. ratti larvae external to the host is determined at a relatively early stage before the first molt.     

Effects of Metarhizium anisopliae conidia mixed with soil against the eggs of Aedes aegypti

The effectiveness of Metarhizium anisopliae IP 46 conidia mixed with soil was tested against Aedes aegypti eggs. Mycelium and new conidia developed first on eggs between 4.8 and 15 days respectively after incubation of fungus-treated soils at 3.3 × 10³ up to 3.3 × 10⁵ conidia/g soil at 25°C and relative humidities close to saturation. After 15-day incubation, 53.3% of the eggs exposed to soil with 3.3 × 10⁵ conidia/g showed external development of mycelium and conidia. Fungus-inoculated soils (but not untreated controls) showed some mycelial growth and sporulation apart from the eggs. Some eggs on treated soils hatched; those larvae died and eventually showed fungal development on their bodies. The cumulative relative eclosion of larvae after submersion of treated eggs in water decreased from 52.2% at 3.3 × 10³ conidia/g to 25.3% at 3.3 × 10⁵ conidia/g. These findings clearly showed that A. aegypti eggs can be infected by M. anisopliae when deposited on fungus-contaminated soil. The effectiveness of M. anisopliae against gravid females, larvae, and also eggs of A. aegypti underscored the possible usefulness of this fungus as a mycoinsecticide, whether naturally occurring or artificially applied, in the breeding sites of this mosquito.     

Thermal Regulation of Spontaneous Spike Frequency and Concomitant Changes in the Amplitude of Spikes from Cortical Neurons

Studies using living slices of guinea pig sensorimotor cortex showed that changes in temperature from 24°C to 37°C produced stepwise increases in neuron spike frequency at two temperature zones: 27–29°C and 34–36°C. Changes in spontaneous activity were accompanied by decreases in spike amplitude at t < 27°C and t > 34°C. After cooling to 24°C, spike amplitude generally recovered completely when the temperature was increased to 32–34°C. The decrease in spike amplitude at t > 35°C could not be restored by decreasing the temperature. It is suggested that these effects are associated with the K⁺ permeability of neuron membranes.     

Thermoregulatory responses of paraplegic and able-bodied athletes at rest and during prolonged upper body exercise and passive recovery

The thermoregulatory responses of ten paraplegic (PA; T3/4-L4) and nine able-bodied (AB) upper body trained athletes were examined at rest and during prolonged arm-cranking exercise and passive recovery. Exercise was performed for 90 min at 80% peak heart rate, and at 21.5 (1.7)°C and 47.0 (7.8)% relative humidity on a Monark cycle ergometer (Ergomedic 814E) adapted for arm exercise. Mean peak oxygen uptake values for the PA and AB athlete groups were 2.12 (0.41) min⁻¹ and 3.19 (0.38) l · min⁻¹, respectively (P<0.05). At rest, there was no difference in aural temperature between groups [36.2 (0.4)°C for both groups]. However, upper body skin temperatures for the PA athletes were approximately 1.0 °C warmer than for the AB athletes, whereas lower body skin temperatures were cooler than those for the AB athletes (1.3 °C and 2.7 °C for the thigh and calf, respectively). Upper and lower body skin temperatures for the AB athletes were similar. During exercise, blood lactate peaked after 15 min of exercise for both groups [3.33 (1.26) mmol · l⁻¹ and 4.30 (1.03) mmol · l⁻¹ for the PA and AB athletes, respectively, P<0.05] and decreased throughout the remainder of the exercise period. Aural temperature increased by 0.7 (0.5)°C and 0.6 (0.4)°C for the AB and PA athletes, respectively. Calf skin temperature for the PA athletes increased during exercise by 1.4 (2.8)°C (P<0.05), whereas a decrease of 0.8 (2.0)°C (P<0.05) was observed for the AB athletes. During the first 20 min of recovery from exercise, the calf skin temperature of the AB athletes decreased further [−2.6 (1.3)°C; P<0.05]. Weight losses and changes in plasma volume were similar for both groups [0.7 (0.5) kg and 0.7 (0.4) kg; 5.4 (4.9)% and 9.7 (6.2)% for the PA and AB athletes, respectively]. In conclusion, the results of this study suggest that the PA athletes exhibit different thermoregulatory responses at rest and during exercise and passive recovery to those of upper body trained AB athletes. Despite this, during 90 min of arm-crank exercise in a cool environment, the PA athletes appeared to be at no greater thermal risk than the AB athletes. Accepted: 7 May 1997     

Low temperature blocks fluid-phase pinocytosis and receptor-mediated endocytosis in Trypanosoma cruzi epimastigotes

Gold-labeled albumin and transferrin were used to follow at the ultrastructural level the early events and the effect of low temperature on protein uptake by Trypanosoma cruzi epimastigotes. In parasites incubated for 5 min at 28 °C with protein-gold complexes, extracellular markers were found only at the cytostome and/or the flagellar pocket regions, whereas intracellular gold particles were detected inside small uncoated vesicles located nearby. Within 10 min, labeling was also observed in uncoated vesicles close to the nucleus. Only after 30 min could the tracers be detected in the reservosomes. Weak labeling in the cytostome and flagellar pocket of parasites incubated at 4 °C with the albumin-gold solution indicated that albumin uptake occurred by fluid-phase pinocytosis. On the other hand, intense labeling at the cytostome was observed in parasites incubated at 4 °C with gold-labeled transferrin, showing that receptor-mediated endocytosis occurs mainly at this site. Both proteins were absent from the cells at 4 °C and 12 °C. Raising the temperature from 12 °C to 28 °C led to transferrin labeling in intracellular vesicles dispersed throughout the cytoplasm, but not in reservosomes. Our results suggest that low temperatures affect the transport and pinching of endocytic vesicles as well as the rate of delivery of transferrin to reservosomes. Received: 3 May 1999 / Accepted: 6 September 1999     

Prediction of the average skin temperature in warm and hot environments

The prediction of the mean skin temperature used for the Required Sweat Rate index was criticised for not being valid in conditions with high radiation and high humidity. Based on a large database provided by 9 institutes, 1999 data points obtained using steady-state conditions, from 1399 experiments and involving 377 male subjects, were used for the development of a new prediction model. The observed mean skin temperatures ranged from 30.7 °C to 38.6 °C. Experimental conditions included air temperatures (T _a) between 20 and 55 °C, mean radiant temperatures (T _r) up to 145 °C, partial vapour pressures (P _a) from 0.2 to 5.3 kPa, air velocities (v _a) between 0.1 and 2 m/s, and metabolic rates (M) from 102 to 620 W. Rectal temperature (T _re) was included in the models to increase the accuracy of prediction. Separate models were derived for nude (clothing insulation, I_cl, ≤0.2 clo, where 1 clo=0.155 m² · °C · W⁻¹, which is equivalent to the thermal insulation of clothing necessary to maintain a resting subject in comfort in a normally ventilated room, air movement=10 cm/s, at a temperature of 21 °C and a humidity of less than 50%) and clothed (0.6 ≤ I_cl ≤ 1.0 clo) subjects using a multiple linear regression technique with re-sampling (non-parametric bootstrap). The following expressions were obtained for nude and clothed subjects, respectively: T _sk=7.19 + 0.064T _a + 0.061T _r + 0.198P _a− 0.348v _a + 0.616T _re and T _sk=12.17 + 0.020T _a + 0.044T _r + 0.194P _a − 0.253v _a + 0.0029M + 0.513T _re. For the nude and clothed subjects, 83.3% and 81.8%, respectively, of the predicted skin temperatures were within the range of ±1 °C of the observed skin temperatures. It is concluded that the proposed models for the prediction of the mean skin temperature are valid for a wide range of warm and hot ambient conditions in steady-state conditions, including those of high radiation and high humidity. Accepted: 7 February 2000     

A thermoresistant strain of feline immunodeficiency virus (FIV) with an altered cytopathic effect and a restricted cell tropism

Summary.  A thermoresistant strain, designated m41, of feline immunodeficiency virus (FIV) was selected after 31 successive passages of chronically infected IRC4 cells at 41 °C. The wild-type virus (wt) which served as a control was cultivated the same number of times at 37 °C. In Crandell feline kidney cells (CrFK), the replication of m41 was similar at 37 °C and 41 °C, whereas wt multiplied only at 37 °C. Furthermore, m41 was more resistant than the wt strain at temperatures ranging from 37 to 56 °C. Syncytia formation was observed with m41 when the CrFK were incubated at 41 °C whereas neither m41 nor wt produced syncytia at 37 °C. The level of replication of wt and m41 on feline lymphoid primary cells at 37 °C was similar. In contrast to wt, m41 was unable to infect bone marrow macrophages. Since one or several mutations in the envelope (env) gene could be involved in changes of cell fusion properties and of cellular tropism, the nucleotide sequence of the env gene derived from wt and m41 respectively was determined. Ten mutations were found in the env gene of m41, thus leading to 9 amino acid modifications in the envelope glycoproteins. These results suggest that structural modifications of the viral envelope proteins are prerequisites for the replication of a thermoresistant FIV strain at elevated temperature and are correlated with the newly acquired viral phenotype. Received March 17, 1998 Accepted June 24, 1998     

Paramphistomum daubneyi and Fasciola hepatica: influence of temperature changes on the shedding of cercariae from dually infected Lymnaea truncatula

Dual infections of Lymnaea truncatula with Paramphistomum daubneyi and Fasciola hepatica were performed to determine whether temperature changes in snails (daily water change with spring water at 6°–8 °C, which subsequently increased to room temperature at 20 °C) would influence snail infection and the production of cercariae by both trematodes. At day 30 postexposure the surviving snails were individually placed in petri dishes to constitute two groups. Snails from the first group were maintained at a temperature of 20 °C, and the water in the petri dishes was changed daily. The protocol was identical for the second group of snails except that the water temperature was 6°–8 °C when changed. The interval between exposure and the first shedding of cercariae in snails immersed in cold water for a short period was longer (67–69 days instead of 48–50 days in the 20 °C group). In both groups, snails infected only with F. hepatica or P. daubneyi or with both trematodes were detected. In snails infected only with F. hepatica the frequency of cercaria-shedding snails and the total number of metacercariae were significantly greater in the 20 °C group. Inversely, in snails infected only with P. daubneyi the frequency of cercaria-shedding snails and the number of metacercariae were significantly greater in the 6°–8 °C group. In snails harboring both trematode larval forms, no significant difference in the frequencies of cercaria-shedding snails between the two groups was noted. Metacercariae of both trematodes were obtained from these snails. In the 20 °C group, F. hepatica metacercariae were more numerous, whereas in the 6°–8 °C group the number of P. daubneyi metacercariae was greater. From these results it appears that greater activity of P. daubneyi cercariae occurs in snails subjected to daily temperature changes (from 6° to 20 °C). Received: 24 March 1999 / Accepted: 1 April 1999     

Melatonin has no effect on tolerance to uncompensable heat stress in man

This study examined whether a 5 mg dose of melatonin induced a lower rectal temperature (T _re) response at rest in both a cool and hot environment while wearing normal military combat clothing, and then examined the influence of this response on tolerance to exercise in the heat while wearing protective clothing. Nine men performed four randomly ordered trials involving 2 h of rest at ambient temperatures of either 23 °C or 40 °C followed by exercise at an ambient temperature of 40 °C. The double-blind ingestion of placebo or melatonin occurred after 30 min of rest. The mean T _re during rest at 23 °C had decreased significantly from 36.8 (SD 0.1) °C to 36.7 (SD 0.2) °C at 90 min following the ingestion of the drug, whereas values during the placebo trial did not change. The lower T _re response during the melatonin trial remained during the first 50 min of exercise in the heat while wearing the protective clothing. Since the final mean T _re at the end of exercise also was significantly reduced for the melatonin [39.0 (SD 0.4) °C] compared with the placebo [mean 39.1 (SD 0.3) °C] trial, tolerance times approximated 95 min in both conditions. During rest at 40 °C, melatonin did not affect the mean T _re response which increased significantly during the last 90 min from 36.9 (SD 0.1) °C to 37.3 (SD 0.1) °C. This increase in T _re during the rest period prior to donning the protective clothing decreased tolerance time approximately 30 min compared with the trials that had involved rest at 23 °C. Total heat storage summated over the rest and exercise periods was not different among the trials at 15 kJ · kg⁻¹. It was concluded that the small decrease in T _re following the ingestion of 5 mg of melatonin at rest in a cool environment had no influence on subsequent tolerance during uncompensable heat stress. Accepted: 26 June 2000     

Measurement and prediction of peak shivering intensity in humans

Prediction equations of shivering metabolism are critical to the development of models of thermoregulation during cold exposure. Although the intensity of maximal shivering has not yet been predicted, a peak shivering metabolic rate (Shiv_peak) of five times the resting metabolic rate has been reported. A group of 15 subjects (including 4 women) [mean age 24.7 (SD 6) years, mean body mass 72.1 (SD 12) kg, mean height 1.76 (SD 0.1) m, mean body fat 22.3 (SD 7)% and mean maximal oxygen uptake (V˙O_2max) 53.2 (SD 9) ml O₂ · kg⁻¹ · min⁻¹] participated in the present study to measure and predict Shiv_peak. The subjects were initially immersed in water at 8°C for up to 70 min. Water temperature was then gradually increased at 0.8 °C · min⁻¹ to a value of 20 °C, which it was expected would increase shivering heat production based on the knowledge that peripheral cold receptors fire maximally at approximately this temperature. This, in combination with the relatively low core temperature at the time this water temperature was reached, was hypothesized would stimulate Shiv_peak. Prior to warming the water from 8 to 20 °C, the oxygen consumption was 15.1 (SD 5.5) ml · kg⁻¹ · min⁻¹ at core temperatures of approximately 35 °C. After the water temperature had risen to 20 °C, the observed Shiv_peak was 22.1 (SD 4.2) ml O₂ · kg⁻¹ · min⁻¹ at core and mean skin temperatures of 35.2 (SD 0.9) and 22.1 (SD 2.2) °C, respectively. The Shiv_peak corresponded to 4.9 (SD 0.8) times the resting metabolism and 41.7 (SD 5.1)% of V˙O_2max. The best fit equation predicting Shiv_peak was Shiv_peak (ml O₂ · kg⁻¹ · min⁻¹)=30.5 + 0.348 ×V˙O_2max (ml O₂ · kg⁻¹ · min⁻¹) − 0.909 × body mass index (kg · m⁻²) − 0.233 × age (years); (P=0.0001; r ²=0.872). Accepted: 7 September 2000     

Improvements in the infectivity of cryopreserved third-stage larvae of Angiostrongyluscantonensis using a programmable freezer

Although there have been some advances in the cryopreservation of Angiostrongyluscantonensis, the degrees of viability and infectivity of the cryopreserved developmental stages have not been high. A two-step freezing protocol using a programmable freezer was determined to be effective in improving the infectivity of the cryopreserved third-stage larvae of this parasite. After washing steps and suspension in 10% (v/v) dimethylsulfoxide and equilibrium at room temperature the larvae were placed into the freezer. The temperature was lowered first at 0.8 °C/min from room temperature to −40 °C and then at 10 °C/min to −70 °C. The samples were plunged into liquid nitrogen. After storage in liquid nitrogen for 7–15 days the larvae were thawed rapidly in 37 °C water and 27.6% were found to show vigorous “S-shape” movement without significant changes in appearance. These larvae (50/rodent) could develop to the fifth stage in mice (42.6%) and establish patent infection in rats (40.4%). Moreover, there was no significant difference in the recovery rates of cryopreserved worms and their unfrozen counterparts. These findings indicate that steady precooling conditions may decrease damage with regard to the infectivity of cryptopreserved third-stage larvae of A. cantonensis. Received: 5 July 1998 / Accepted: 5 August 1998     

Thermoregulatory effects of three different types of head cooling in humans during a mild hyperthermia

Seven healthy young men participated in six trials with three different types of local cooling [cool air breathing (CAB), face skin cooling (FaC), and combined cooling (CoC)] in a warm environment for 90 min while either resting (operative temperature: T ₀ = 40°C, dew point temperature: T _dp = 15°C, air velocity: v _a = 0.3 m·s⁻¹) or exercising on a cycle ergometer with an external work load of 90 W (T ₀ = 36°C, T _dp = 15°C, v _a = 0.3 m·s⁻¹). Cool air (10°C) arrived at the entry point of the hood and/or the mask at a ventilation rate of 12 m · s⁻¹. Oesophageal temperature was not affected by any kind of cooling, while tympanic temperature was decreased at rest by both FaC and CoC [respectively −0.15 (0.06) and −0.09 (0.03)°C, P ≤ 0.05]. Mean skin temperature was decreased by FaC and CoC at rest [respectively −0.31 (0.07) and −0.27 (0.09)°C, P ≤ 0.05] and during exercise [respectively −0.64 (0.15) and −1.04 (0.22)°C, P ≤ 0.01]. CAB had no effect on skin temperatures. CoC and FaC reduced head skin temperature during both rest and work (P < 0.001) with no effect on the skin temperature of the rest of the body, except under CoC with exercise (P < 0.05). CAB did not influence local sweating. FaC, however, decreased the more profuse sweat rates (P ≤ 0.05) at rest, while CoC decreased all sweating rates at rest (P ≤ 0.05) and only the back, head and leg sweating rates during exercise (P ≤ 0.05). These results suggest that head skin cooling causes a reduction in heat strain, while CAB does not. This beneficial influence does not, however, appear to be the result of selective brain cooling. Tympanic temperature seems to be a good index of the core thermal inputs to the hypothalamic regulatory system, since variations in that parameter were associated with similarly directed variations in the sweating outputs. Accepted: 12 April 1999     

Anthelmintic effect of a methanol extract of <Emphasis Type="Italic">Bombax malabaricum</Emphasis> leaves on <Emphasis Type="Italic">Paramphistomum explanatum</Emphasis>

Bombax malabaricum (family Bombacaceae) is used as anthelmintic in traditional system of medicine in Southern Punjab of Pakistan. The objective of this study was to evaluate the anthelmintic activity of the methanol extract of B. malabaricum leaves (MEBM). Live parasites (trematode: Paramphistomum explanatum) were collected from buffalo in 0.9% phosphate-buffered saline. It was incubated in Petri dishes at 37 ± 1°C in media containing either no extract (control) or MEBM, the test drug at 10, 25, 50, and 100 mg/ml dose level or albendazole, the standard drug at 10 mg/ml. The efficacy of the extract or albendazole was measured on the basis of the loss of spontaneous movement and/or death of the trematodes. Paralysis was considered when there is no movement unless shaken vigorously. Death was confirmed when the trematodes completely lost their motility, even when vigorously shaken or dipped in warm water (50°C), followed by fading away of their body color. The trematodes, both drug treated and others, were further processed for SEM study using the standard method. All trematodes died with all the above-mentioned doses of MEBM within a short period of time (less than 45 min) which was statistically highly significant (p < 0.001). MEBM at 100 mg/ml showed maximum efficacy. It paralyzed and killed trematodes in 18.50 ± 0.62 and 22.17 ± 0.48 min, respectively. SEM study showed that MEBM-treated trematodes were stretched. The study established the anthelmintic activity of MEBM.