Biomedical subjects

S E Radloff

Publications and source records attributed to S E Radloff.

6 recordsLinked to original sources

PubMed2006

Gigantism in honeybees: Apis cerana queens reared in mixed-species colonies.

The development of animals depends on both genetic and environmental effects to a varying extent. Their relative influences can be evaluated in the social insects by raising the intracolonial diversity to an extreme in nests consisting of workers from more than one species. In this study, we studied the effects of mixed honeybee colonies of Apis mellifera and Apis cerana on the rearing of grafted queen larvae of A. cerana. A. mellifera sealed worker brood was introduced into A. cerana colonies and on emergence, the adults were accepted. Then, A. cerana larvae were grafted for queen rearing into two of these mixed-species colonies. Similarly, A. cerana larvae and A. mellifera larvae were also grafted conspecifically as controls. The success rate of A. cerana queen rearing in the test colonies was 64.5%, surpassing all previous attempts at interspecific queen rearing. After emergence, all virgin queens obtained from the three groups (N=90) were measured morphometrically. The A. cerana queens from the mixed-species colonies differed significantly in size and pigmentation from the A. cerana control queens and closely approximated the A. mellifera queens. It is inferred that these changes in the A. cerana queens reared in the mixed-species colonies can be attributed to feeding by heterospecific nurse bees and/or chemical differences in royal jelly. Our data show a strong impact of environment on the development of queens. The results further suggest that in honeybees the cues for brood recognition can be learned by heterospecific workers after eclosion, thereby providing a novel analogy to slave making in ants.

Animals↗

PubMed2005

Heat-balling wasps by honeybees.

Defensiveness of honeybee colonies of Apis cerana and Apis mellifera (actively balling the wasps but reduction of foraging) against predatory wasps, Vespa velutina, and false wasps was assessed. There were significantly more worker bees in balls of the former than latter. Core temperatures in a ball around a live wasp of A. cerana were significantly higher than those of A. mellifera, and also significantly more when exposed to false wasps. Core temperatures of bee balls exposed to false wasps were significantly lower than those exposed to V. velutina for both A. cerana and for A. mellifera. The lethal thermal limits for V. velutina, A. cerana and A. mellifera were significantly different, so that both species of honeybees have a thermal safety factor in heat-killing such wasp predators. During wasps attacks at the hives measured at 3, 6 and 12 min, the numbers of Apis cerana cerana and Apis cerana indica bees continuing to forage were significantly reduced with increased wasp attack time. Tropical lowland A. c. indica reduced foraging rates significantly more than the highland A. c. cerana bees; but, there was no significant effect on foraging by A. mellifera. The latency to recovery of honeybee foraging was significantly greater the longer the duration of wasp attacks. The results show remarkable thermal fine-tuning in a co-evolving predator-prey relationship.

Animals↗

PubMed2005

Effects of ethanol and water extracts of propolis (bee glue) on acute inflammatory animal models.

The anti-inflammatory effects of ethanol (EEP) and water (WSD) extracts in ICR mice and Wistar rats were analyzed. Both WSD and EEP exhibited significant anti-inflammatory effects in animal models with respect to thoracic capillary vessel leakage in mice, carrageenan-induced oedema, carrageenan-induced pleurisy, acute lung damage in rats. The mechanisms for the anti-inflammatory effects probably involve decreasing prostaglandin-E(2) (PGE(2)) and nitric oxide (NO) levels. In rats with Freund's complete adjuvant (FCA) induced arthritis, propolis extracts significantly inhibited the increase of interleukin-6 (IL-6) in inflamed tissues, but had no significant effect on levels of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). The results are consistent with the interpretation that EEP and WSD may exert these effects by inhibiting the activation and differentiation of mononuclear macrophages.

Animals↗

PubMed2005

Effects of propolis on blood glucose, blood lipid and free radicals in rats with diabetes mellitus.

The effects of ethanol (EEP) and water (WSD) extracts of propolis collected from north China on blood glucose, blood lipid and free radicals in rats with diabetes mellitus were studied. The results show that EEP and WSD led to decreased levels of blood glucose (FBG), fructosamine (FRU), malonaldehyde (MDA), nitric oxide (NO), nitric oxide synthetase (NOS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C) in serum of fasting rats; and to increased serum levels of high-density lipoprotein cholesterol (HDL-C) and superoxide dismutase (SOD). This suggests that propolis can control blood glucose and modulate the metabolism of glucose and blood lipid, leading to decreased outputs of lipid peroxidation and scavenge the free radicals in rats with diabetes mellitus.

Animals↗

PubMed2004

Honeybee combs: construction through a liquid equilibrium process?

Geometrical investigations of honeycombs and speculations on how honeybees measure and construct the hexagons and rhombi of their cells are centuries old. Here we show that honeybees neither have to measure nor construct the highly regular structures of a honeycomb, and that the observed pattern of combs can be parsimoniously explained by wax flowing in liquid equilibrium. The structure of the combs of honeybees results from wax as a thermoplastic building medium, which softens and hardens as a result of increasing and decreasing temperatures. It flows among an array of transient, close-packed cylinders which are actually the self-heated honeybees themselves. The three apparent rhomboids forming the base of each cell do not exist but arise as optical artefacts from looking through semi-transparent combs.

Animals↗

PubMed1997

Quantitative ultrasound of the calcaneus reflects the mechanical properties of calcaneal trabecular bone.

To provide new information about the potential role of quantitative ultrasound (QUS) in fracture risk prediction, we assessed whether QUS and densitometric variables derived from measurements of intact cadaveric feet were associated with the mechanical properties of calcaneal trabecular bone. We obtained 31 intact cadaveric feet from the local anatomic gifts program, including 13 men and 18 women, with a mean age of 77 years (range 50-91 years). Broadband ultrasound attenuation (BUA) and ultrasound transit velocity (SOS) were assessed in the intact cadaveric feet using a water-based ultrasound system. In addition, we measured the bone mineral density (BMD) of the posterior calcaneus using dual-energy X-ray absorptiometry. Cubes of trabecular bone were then removed from the calcaneus at approximately the same location as the QUS measurements were obtained, and the elastic modulus and ultimate strength of the trabecular bone specimens were measured by compressing them in the mediolateral direction. We found that QUS variables were moderately to strongly correlated with the mechanical properties of calcaneal trabecular bone (r2 = 0.48-0.63, p < 0.001 for all). However, the strongest associations with the mechanical properties trabecular bone were provided by calcaneus BMD and trabecular bone apparent density (r2 = 0.66-0.88). BUA and densitometric measurements were independently associated with elastic modulus, but not with ultimate strength. Our results indicate that QUS measurements of the intact heel are associated with the mechanical properties of calcaneal trabecular bone and, in some cases, provide information in addition to that provided by BMD or density measurements.

Absorptiometry, Photon↗