Reproductive disorders among hairdressers

A systematic theoretical study on histamine agonists and their interaction with H1 and H2 receptor models has been carried out utilizing ab initio molecular orbital technique. The effect of substituents on histamine agonists' charge distribution and their agonistic activity has been studied in detail. Drug-receptor interaction models have been studied at the Hartree Fock level of theory with a split valence basis set keeping the cost and efficiency of the calculation in mind. The study indicates that the agonistic activity is controlled either by receptor conformation or by steric hinderances caused by the substituents. The monocationic form of histamine does not appear to be a necessity for a proton relay process which is similar to the one proposed earlier by Weinstein and coworkers. The study also indicates some importance of common cellular ions in neurotransmitter properties of histamine.     

Computer simulations of surfactants and surfactant/polymer assemblies

Applications of computer simulation methods, such as atomistic simulation, coarse-grain simulation and mesoscopic simulation, on surfactant assemblies at the interface, surfactant aggregates, and the surfactant/polymer assemblies were summarized based on our works. And the development and prospect of applying computer simulation to study self-assembling surfactant systems were also referred to.     

CT findings in chondroradionecrosis of the larynx

PURPOSE: Our goal was to describe the CT findings before and after radiation therapy in a series of patients with laryngeal chondroradionecrosis. METHODS: The CT studies obtained before and after radiation therapy in nine patients with the diagnosis of laryngeal chondroradionecrosis were reviewed retrospectively. RESULTS: CT scans revealed abnormalities in all patients. A variable degree of laryngeal soft-tissue swelling was seen in eight of the patients. In four patients, cartilaginous abnormalities were visible initially, and appeared in three of four other patients who had further follow-up CT studies. Six patients had involvement of the thyroid cartilage; collapse of the thyroid cartilage was seen in two cases and gas bubbles were visible adjacent to the thyroid cartilage in three cases. Four patients with involvement of the thyroid cartilage eventually underwent total laryngectomy, and one died suddenly in severe respiratory distress. In all three patients with arytenoidal involvement, anterior dislocation of this cartilage was seen; in two of these patients, the adjacent part of the cricoid cartilage showed some sclerosis. Two patients with arytenoidal necrosis (both with cricoidal sclerosis) kept a functional larynx. In one case, cricoidal sclerosis was seen in association with lysis of the thyroid cartilage. CONCLUSION: The CT appearance of laryngeal chondroradionecrosis is nonspecific, but the diagnosis can be strongly suggested in cases of sloughing of the arytenoid cartilage, fragmentation and collapse of the thyroid cartilage, and/or in the presence of gas bubbles around the cartilage.     

Assessment of the clinical significance of anti-Dob

BACKGROUND: Anti-Dob is an uncommon antibody, and there are few data regarding its clinical importance. In the present case, the patient's transfusion management was based on both in vivo and in vitro assay results. CASE REPORT: A delayed hemolytic transfusion reaction was suspected in a 64-year-old white woman awaiting cardiac surgery when the transfusion of 1 unit of red cells failed to raise her hematocrit. Although direct antiglobulin tests were negative, antibody screening tests on samples drawn 9 days after transfusion were positive, and anti-Dob was identified, reacting to a titer of 4. 51Cr in vivo survival studies with incompatible Do(b+) red cells showed poor survival: 83.2 percent at 1 hour, 43 percent at 24 hours, and 29.6 percent at 48 hours and t1/2 = 19 hours (normal t1/2 = 25-35 days). A monocyte monolayer assay performed with the same incompatible Do(b+) donor red cells also indicated poor survival: 22 percent and 30 percent reactive monocytes, respectively, with and without the addition of complement (normal, 0-3%). The patient was given 4 Do(b-) red cell units without clinical signs or symptoms of a reaction. CONCLUSIONS: This example of anti-Dob was implicated in a delayed hemolytic transfusion reaction. The 51Cr survival studies and monocyte monolayer assay results indicated that the anti-Dob was clinically significant, requiring the use of Do(b-) red cells for transfusion.     

The biological basis of grooming in moose: programmed versus stimulus-driven grooming

In domestic and wild mammals, tick infestation can be a significant fitness cost. Grooming behaviour has been shown to be effective in removing ticks. We studied grooming by moose, Alces alces, infested with winter ticks, Dermacentor albipictus, to determine which of two nonexclusive models for the regulation of tick-removal grooming, programmed or stimulus driven, best fit this host-parasite relationship. The programmed grooming model states that most grooming is driven by an internal timing mechanism which periodically evokes a bout a grooming independent of peripheral stimulation from tick bites. Because programmed grooming is preventive, the model predicts that those animals that groom the most will carry the fewest ticks, and a baseline level of programmed grooming is predicted even in a tick-sparse or tick-free environment. The stimulus-driven grooming model, on the other hand, states that grooming is a direct response to cutaneous irritation caused by tick bites and other sources of irritation. This stimulus-driven model predicts that (1) animals showing the highest rate of grooming will carry the most ticks and (2) animals will groom little when tick challenge is low. Both predictions of the stimulus-driven model were supported for moose: (1) calves oral-groomed three times more than cows, and tick densities on calves were three times higher than on cows; and (2) although all moose carried high densities of immature winter ticks (larvae, nymphs) from October through to February, grooming rate was very low until adult ticks started feeding in March-April. Peak grooming rates occurred during adult tick engorgement in March-April. Because an engorging adult female tick produces far more irritation than an engorging nymphal or larval tick, moose appeared to groom in direct proportion to the degree of cutaneous irritation and did not show a baseline level of grooming. The predominance of stimulus-driven grooming and apparent absence of programmed grooming may be the result of relaxed selection pressure for grooming in the evolutionary history of moose. Because the winter tick appears to have been introduced to moose from deer relatively recently, moose may not have had the time to adapt to winter ticks. The coevolutionary relationship between moose and winter ticks may be of insufficient duration for the evolution and/or maintenance of programmed grooming. (c) 1998 The Association for the Study of Animal Behaviour.     

抽油机井热洗效果与节能的关系

影响抽油机井热洗效果因素较多,主要受抽油机井自身条件、热洗周期及热洗参数限制.制定合理的热冼周期并确定合理的热洗参数,既能保证热洗质量又能达到节能的目的.本文通过对抽油机井的具体参数分析,合理制定最佳热洗周期及热洗参数,达到了既节能又保证热洗质量的目的.     

二次杀菌、二次均质等技术在搅拌酸奶生产中的应用

在酸奶的生产过程中有著很多关乎产品质量的关键技术点.通过调研和不断地试验,采用二次杀菌、二次均质、脱气等关键技术,采改进搅拌酸奶生产工艺,进而提高产品质量.