Unsteady Fluid Dynamics of Several Mechanical Prosthetic Heart Valves Using a Two Component Laser Doppler Anemometer System

Abstract: Five typical mechanical heart valves (Starr-Edwards, Björk-Shiley convexo-concave (c-c), Björk-Shiley monostrut, Bicer-Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component laser Doppler anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level.     

Urogenitales Altern

In the industrial Western world, 8 % of the population suffer from urogenital discomfort. Epidemiologic studies show that the incidence rises with age. In light of the steadily increasing longevity in the female population, clinically manifested irregularities such as urogenital atrophy, recurrent urinary tract infections, irritable bladder, and incontinence pose a challenge to the attending physician. To this day, urinary incontinence in later life is considered “normal” and “caused by old age.” However, among other age-related reasons, the main cause of this disorder is postmenopausal hormone deficiency. Thus, following thorough diagnostics, pathological changes in the urogenital tract can often be reduced or altogether eliminated by simple conservative measures such as topical hormone administration, which rapidly enhance patients’ quality of life. The present study gives an overview of the physiology of urogenital aging and the diagnostic and therapeutic means available to physicians to alleviate patients’ discomfort.     

The pineal gland and reproduction

The hormonal activity of the pineal gland is influenced by boththe dark-light cycle and the seasonal cycle, causing it to playan important role in the neuroendocrine control of reproductivephysiology. This is especially evident in seasonally breedinganimals, in which reproductive function is clearly influencedby seasonal variations in the duration of night and day. Humansare not seasonal breeders. Nevertheless, seasonal fluctuationshave been described in human reproduction, and the pineal glandalso appears to exert an important role in the neuroendocrineregulation of human reproductive physiology. There is evidencethat the epiphysis is involved in the control of sexual maturation.In rats, the maternal pineal appears to influence the gonadaland genital development and function of offspring; this hypothesishas yet to be confirmed in humans. The pineal apparently influenceshuman reproductive function not only at the hypothalamic-pituitarylevel, by inhibition of the hypothalamic pulsatile secretionof gonadotrophin-releasing hormone, but also at the gonadallevel, where melatonin receptors have also been found. In addition,melatonin is reported to increase serum prolactin concentrationsin both rats and humans. It has been suggested that melatoninis involved in the control of menstrual cyclicity.     

Antiarrhythmic effect ofRodiola rosea and its possible mechanism

Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 116, N ^o 8, pp. 175–176, August, 1993     

Bovine colostrum immunoglobulin concentrate for cryptosporidiosis in AIDS.

Lactobin-R is a commercial hyperimmune bovine colostrum with potent anticryptosporidial activity. It was administered to a 4 year old child with AIDS and severe diarrhoea associated with cryptosporidiosis. There was significant clinical improvement in the diarrhoea and permanent elimination of the parasite from the gut as assessed through serial jejunal biopsy and stool specimens.     

Basic principles and methods of aid to patients with severe hand trauma

Aid rendering to the patients with severe hand trauma is presented as a system of primary-reconstructive treatment, including individual approach to the surgical aid tactics, terms and volume selection, where the defining factors are the state of tissue blood circulation, application of the complex of conservative and operative measures aimed at the prophylaxis and therapy of circulatory and infectious complications, selection of rational methods of the lost anatomic formations reconstruction. There are described clinical criteria of tissue vitality evaluation and those obtained with application of instrument methods (infrared thermography, electric resistance thermometry, ultrasound indication of blood flow). If the state of the damaged hand tissues requires medicinal treatment it would be expedient to carry out the primary-postponed treatment, consisting of 2 stages. The first stage includes surgical manipulation, aimed at microcirculation improvement and wound surface isolation by means of watertight cover. The second stage is the final one. Its volume depends upon the compensation of tissue blood flow and is carried out for 2-5 days in planned order.