Nobu Ohwatari

TGF-β1 mediates 70-kDa heat shock protein induction due to ultraviolet irradiation in human skin fibroblasts

Abstract Ultraviolet B (UVB) alters the expression of heat shock protein 70 (HSP70) in cultured fibroblast cells derived from human skin. However, the nature of the signal transduction pathway remains to be determined. Transforming growth factor-β (TGF-β) has a large variety of biological functions, including cell growth control, modulation of inflammation and immunoregulation. In this study, we examined whether TGF-β is associated with the process of HSP70 expression induced by UVB irradiation. The constitutive expression of TGF-β1 mRNA and HSP70 expression in human skin fibroblast cells were detected using reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The results indicate that: (1) UVB irradiation stimulates HSP70 expression in a dose- and time-dependent manner, (2) constitutive expression of TGF-β1 mRNA is detected after UVB irradiation, the level of which peaks at 4 h after 10 mJ cm–2 of UVB irradiation, (3) HSP70 expression is induced by TGF-β1 without UVB irradiation, and (4) HSP70 expression induction with UVB irradiation is inhibited by preincubation of the cells with the anti-TGF-β type II receptor antibody. Our results suggest that HSP70 expression induced by UVB involves the autocrine signalling of TGF-β production.

Resistance to reinfection in rats induced by irradiated metacercariae of Clonorchis sinensis

A study was made to observe the association between the resistance to reinfection induced by irradiated metacercariae (MC) of Clonorchis sinensis and antigen specific Th1- and Th2-type cytokine productions in rats. Rats were infected with 20 MC of C. sinensis, previously exposed to a single dose of gamma irradiation, which varied from 0 to 100 Gy. All of them, single dose of 12 Gy showed higher IgG antibody titer with lowest worm recovery. Thus, 50 MC were used to challenge infection in rats previously infected with 20 MC irradiated at 12 Gy and the highest resistance to challenge infection was observed. The results of lymphocyte proliferation with specific antigen, ES Ag were shown no difference of proliferative responses as compared with primary and challenge infection at 12 Gy irradiation dose. In the case of cytokines production were observed that interferon (IFN-gamma) and interlukin (IL-2) were significantly enhanced, while IL-4 and IL-10 was almost unchanged to make comparison between primary and secondary infection at 12 Gy irradiation dose. In conclusion, the single dose of 12 Gy could be adopted for induction of the highest resistance to challenge infection. Up-regulation of Th1 type cytokines, IFN-gamma and IL-2 may be affected to develop vaccine by irradiated MC.

Sweating economy by graded control in well-trained athletes

Abstract Local sweat rates (Msw) at the chest and thigh and the frequency of sweat expulsions (Fsw) were determined in human subjects with (athletes) or without (non-athletes) long-term physical training during moderate bicycle exercise (80 W for 30 min) at ambient thermoneutrality (23°C) and 60% relative humidity. There was a tendency for Msw to be lower in athletes. The rise of Msw with increasing Fsw was significantly less steep and Fsw was also controlled at a significantly lower rate in athletes than in non-athletes. The start of exercise was followed by a temporary decrease in mean skin temperature (T-s) which was less distinct in athletes. The rise in T-s at the end of exercise was significant in athletes (0.80 ± 0.26°C) but not in non-athletes (0.26 ± 0.33°C). The results indicate that long-term physical training leads to improved circulatory heat transfer to the skin and to a more graded nervous control of sweat expulsion and, further, tends to reduce the rate of sweating.

Analysis of sweat evaporation from clothing materials by the ventilated sweat capsule method

Abstract The local influence of three clothing materials i.e. silk, cotton and nylon, in (1) full or (2) partial skin contact or (3) at 3 mm from the skin, on sweat evaporation from the chest skin surface of human subjects was studied. The hygrometer-ventilated capsule method was used and sweating was induced at ambient thermoneutrality by a central heat load following lower-leg immersion in water at 43°C. The presence of clothing delayed the rise in capsule relative humidity (CRH) induced by heat loading. During the first 6 min of heating, CRH rose more steeply with clothing that was in full skin contact than with clothing that had partial or no contact. The rate of decrease in CRH from 1 min to 6 min after heating was not influenced by the presence of clothing or by the different degrees of skin contact. The subsequent return of CRH to the pre-heating level was delayed most by cotton, less by silk and least by nylon. For silk and nylon, partial contact with the skin prolonged the return to control conditions, as compared with full skin contact.

Central and Peripheral Control of Sweating Mechanisms: Modifications by Thermal Acclimatization and Physical Training

Sweating is a heat loss response that is critical for improved physical performance and safety in extremely hot conditions. It is centrally regulated by the preoptic area and anterior hypothalamus and peripherally transmitted by sympathetic sudomotor innervation, with acetylcholine (ACh) as the primary neuroglandular transmitter. Modification of sweating activity through heat exposure or physical training is a physiological tactic for improved tolerance when individuals are challenged with exogenous or endogenous heat. A short-term heat challenge produces a lower resting and slower increase in body temperature as well as enhanced sweating response, while long-term heat exposure results in decreased sweat output. Cold acclimation results in reduced thermoneutral and skin temperatures, lowered cold sensation, and reduced metabolic heat production. Physical training induces higher sweat output by means of greater sweat output per activated sweat gland, a shorter lag phase for sweating, an increased number of activated sweat glands, and a higher rate of skin blood flow.

Anatomical and neurochemical peculiarities of the pika retina: basis for lack of circadian rhythm of core temperature

We have previously reported a complete lack of circadian rhythm in the body temperature of pikas in contrast to other lagomorphs. In this present study, the anatomical and neurochemical findings by immunohistochemical, photo and electron microscopic methods reveal that the photoreceptor system of this animal is poorly developed. This probably explains their stable core body temperature which help them survive in cold temperatures.

Analysis of sweating induced by VIP iontophoresis in human skin

Abstract In human skin transplanted to the back of three strains of immuno-deficient mice, the function of sweat glands of the human transplant was tested by intradermal application of pilocarpine, adrenaline, atropine+pilocarpine and VIP Sweat responses were observed in the former three substances, not VIP. Therefore, to re-examine the negative results on VIP, interactions of the sudomotor axon reflex (AXR) with putative local mediators were studied by drug iontophoresis. The state of thermoregulation seems to modulate the action of VIP as a possible co-transmitter facilitating AXR by raising skin temperature. The underlying VIP-induced vasodilation may involve both sudomotor and sensory axon reflex mechanisms.

Protective Measures Against Solar Radiant Heat and Ultraviolet Irradiation

Exposure to intense sunlight in warm ambient conditions imposes two kinds of radiant stresses on the human body: (1) heat stress, which activates evaporative heat dissipation as a challenge to fluid and electrolyte balance, and (2) UV irradiation with its potentially damaging and cancerogenic effects on epidermal and dermal cells. Factors that lessen these two potentially health-threatening stresses are reviewed. The heat load imposed by solar radiation is considerably reduced by protective clothing or fur. Their protective action is mainly because heat is transferred to the ambient air more easily from the outermost clothing layers that are heated up by the sun than by conduction through the deeper clothing layers to the skin where it would be absorbed by the body. A precondition for protection by clothing is that it permits water vapor generated by sweat evaporation at the skin surface to diffuse easily into ambient air. Analogous to clothing in its protective value is the fur of animals indigenous to hot desert or steppe conditions. The UV load imposed by solar radiation is particularly intense in dustfree or dry air as may be encountered in still-air desert conditions, at the sea or seashore, and at high altitudes. Natural protection involves skin pigmentation, either genetically provided or acquired by the process of tanning, which both are based on the presence of melanosomes in epidermal cells. In addition, clothing or the use of sunscreens containing compounds aborbing especially the UV-B component provides additional protection, as does the fur of animals that are exposed to intense UV radiation at high altitudes. In the case of skin cell damage by UV-B, expression of genes is induced to synthesize compounds that act in the repair of protein and DNA damage and, as a long-term adaptation, may activate melanin production.

A new approach to analysis of human sweating

In human skin transplanted to the back of 3 strains of immuno-deficient mice the functin of the eccrine sweat glands of the human transplant was tested by topical intradermal application of pilocarine, adrenaline and atropine+pilocarpine. Sweat responses were observed in pre-selected fields of observation by means of video macroscope. The iodine strarch reaction served as an indicator for the appearance of seat sport and permitted the evaluation of areas wetted by sweat in the field of observation. Among 9 animals tested, the hybrids between the CB-17-scid mouse and the BALB/cA-nu mouse (BALB/cA-nu,scid) seemed to exhibit the most consistent seweating response to local pharmacological stimulation. According to histological examination, eccrine sweat glands were preserved in human skin trasplanted into the back skin of the BALB/cA-nu,scid mouse strain. the heterologous, human skin graft provides a novel model permitting, independent of the normal sweat gland innervation, the analysis of moecular receptors of sweat gland cells by which the actions of natural transmitters and pharmacological agents are transduced.

Analysis of Body Temperature and Blood Protein in Hypothermic Syrian Hamsters and Rats

To clarify the ability of cold tolerance of Syrian hamsters (Mesocricetus auratus) during the nonhibernating state as compared with Wistar rats, hypothermia was induced by acute cold exposure at 0°C with ice packs. On skin insulation, the back skin was better than the abdominal skin in both species, and Wistar rats was superior to Syrian hamsters. Minimal temperature in the abdominal cavity of Syrian hamsters in nonhibernation (7.22±0.31°C) was significantly lower than 17.11±0.39°C of Wistar rats. Blood proteins on SDS-PAGE 18hr after acute cold exposure changed as follows: 17.5, 19, 35 and 43 kDa proteins increased and 32 and 40 kDa proteins decreased. A little change occurred in proteins of the brain and kidney of Syrian hamsters.