Effect of adaptation to continuous stress on the contractile function and electric stability of the heart

In the time course of 15-day stress of moderate intensity, rat experiments indicated that following a day there developed a complex of changes typical of acute stressor syndrome. Five days of post-stress , the stress-related cardiac syndrome ceased, bradycardia developed, the contractile function was limited, and the fibrillation threshold returned to the control values, which was shown to be associated with activation of the cholinergic stress-limiting system. Fifteen days later there was normalization of heart rate and cardiac contractility, the fibrillation threshold remained at the baseline level.     

High survial rate of hamsters given intratracheal instillations of benzo[a]pyrene and ferric oxide and kept on a high {beta}-carotene diet

The study described in this paper was primarily conducted toidentify the cell types involved in the formation, progressionand regression of metaplastic changes in the respiratory tractepithelium of hamsters after intratracheal intubations withbenzo[a]pyrene Furthermore, the role of vitamin A and ß;-carotenein these processes was studied. In the course of the study aremarkable effect of dietary ß;-carotene on survivalof hamsters became a subject of investigation. Hamsters werefed diets with various levels of vitamin A or ß-caroteneand were treated intratracheally with a suspension of benzo[a]pyrenewith ferric oxide in saline. The tumour response of the respiratorytract was very low (2.8%) and hyper- and metaplasia of respiratoryepithelium were virtually absent. However, an interesting observationwas an exceptionally low mortality of only 2% after 69 weeksin the group of hamsters fed a high ß-carotene diet(1% w/w), whereas in the other groups mortality after 69 weeksamounted to 25%. Although the exact cause of death of most ofthe hamsters could not be established, a 40% reduction of lipidperoxidation in the livers was found in the high ß-carotenegroup. Moreover, In this group the degree and incidence of nephroslsand of focal mineralization of kidneys and heart were lowerthan in the other groups. These favourable effects of the highß-carotene diet may have contributed to the unusuallyhigh survival rate in hamsters fed this diet. Further studiesare planned to verify and study this observation.     

Use of dimephosphon in pathogenetic therapy of experimental tuberculosis]

The results of a study of a new synthetic drug dimephosphon used as a pathogenetic means in the treatment of experimental tuberculosis are presented. Dimephosphon was found to be responsible for both the in vivo and in vitro decrease of the degree of MBT resistance to rifampicin. The findings of macroscopic, histologic and bacteriologic examinations demonstrated a significant increase in the effectiveness of antituberculous therapy. Dimephosphon monotherapy in mice elicited manifested stimulation of peritoneal macrophages: increase in O2- production, and decline in extracellular 5-nucleotidase activity. Nemolysine-synthetic cellular splenic activity in mice rose essentially. No direct stimulating influence of dimephosphon on functional macrophage activity in vitro was found.     

Expression of alpha-melanocyte stimulating hormone and the invasive ability of the B16 murine melanoma.

The expression of alpha melanocyte stimulating hormone (MSH) has been investigated in two variants of the B16 murine melanoma. The presence of MSH was demonstrated by immunohistochemical methods using anti-MSH antibodies. The low metastasis variant B16-F1, which grows as an encapsulated non-invasive tumour, showed no alpha-MSH immunoreactivity. In contrast, the high metastasis variant BL6 was found to be alpha-MSH positive and the immunoreactivity was found predominantly in the peripheral invading zones of the tumour.     

Na,K-Atpase in renal tissue of rats in the dynamics of experimental nephritis]

The authors undertook comparative study of the Na, K-ATPase activity in the red cells, ghost corpuscles, and in the cortex and medulla of kidneys of rats with experimental glomerulonephritis (GN) induced by injection of nephrotoxic serum (NTS), during an acute course of the process (1 and 2 weeks after NTS injection) and in chronic affection of the kidneys (10 weeks after NTS injection). The activity of the enzyme both in the red cells and in the ghost corpuscles was reduced significantly, by 28 and 22%, respectively, in the acute period of the disease (one week after NTS injection) but was restored to normal values in the period of chronic affection of the kidneys. The activity of the enzyme did not change in the cortex during the whole period of the study, but in the medulla it diminished in the acute period of the disease and remained reduced (by 27% on the average) during the chronic phase. It is concluded that reduction of the enzyme activity in the studied objects was not caused by the presence of endogenous inhibitors of the enzyme. It is suggested that reduction of Na, K-ATPase activity in the renal medulla may be one of the factors of increase of Na and water excretion in the urine in the chronic phase of GN.     

Limb asymmetries in landing and jumping 2 years following anterior cruciate ligament reconstruction.

OBJECTIVE: Female athletes who are at increased risk for anterior cruciate ligament (ACL) injury demonstrate biomechanical differences between limbs during athletic tasks that may persist following anterior cruciate ligament reconstruction (ACLR). This may limit an athlete's potential for safe return to sports competition. The purpose of this study was to determine if female athletes demonstrate lower limb asymmetries in landing and takeoff force following ACLR and clearance for return to competitive sports participation. We hypothesized that females following ACLR would demonstrate side-to-side differences in landing and jumping kinetics after their return to sport (2+ years) that would not be observed in a group of healthy female controls. DESIGN: Case control study. SETTING: The Sports Medicine Biodynamics Center at Cincinnati Children's Hospital Medical Center. PATIENTS: Fourteen female athletes at a mean of 27 months following ACLR and 18 healthy female athletes participated in the study. ASSESSMENT: All subjects executed a drop vertical jump (DVJ) task onto 2 force plates. Vertical ground reaction force (VGRF) was measured during landing and takeoff and was used to calculate landing phase loading rates. A 2-way analysis of variance was used to determine differences between the involved, uninvolved, and control limbs. RESULTS: Females who had undergone ACLR demonstrated increased VGRF (P = 0.001) and loading rate (P < 0.001) on the uninvolved limb during landing when compared with the involved limb and the control group. During takeoff, the involved limb showed significantly less ability to generate force (P = 0.03) than the uninvolved limb and the control limbs. CONCLUSIONS: Female athletes who have undergone ACLR and returned to sport may continue to demonstrate biomechanical limb asymmetries 2 years or more after reconstruction that can be identified during landing.     

Use of antigen-detection enzyme immunoassays in assessment of trypanotolerance in N'Dama cattle.

Antigen-detection enzyme immunoassays (ELISA) were used for the diagnosis of Trypanosoma vivax, T. congolense and T. brucei in N'Dama cattle in Gabon, Central Africa. The assays are based on monoclonal antibodies which recognise trypanosome antigens specific for each of the three species and animals were termed 'antigenaemic' when found positive by this technique but not found parasitaemic by the buffy coat technique. 148 one-year-old animals were exposed to a medium natural tsetse challenge and an average of 6 assays per animal were carried out over a 92-day period. Blood samples were routinely examined 11 times over this period and 28% of animals were detected as parasitaemic by the buffy coat technique. 90% of these were antigen-ELISA positive. More importantly, 40% of the animals with negative parasitological findings were also found to be antigenaemic. Parasitaemic animals with above-average packed-red-cell volume percent (PCV) values had 32% higher daily weight gains than those with below average, while antigenaemic animals showed no significant linkage between PCV values and weight gain. Thus only the 28% of animals with detectable parasitaemias could have been used for selection decisions based on PCV values. Antigenaemic animals grew at the same rate as negative animals and had 22% superior growth rates to parasitaemic animals. When antigenaemic animals were classified as having more ability to control parasite growth than parasitaemic animals, a significant sire effect suggested some possibility of a degree of genetic control being involved. Thus the ELISA could offer a practical possibility for selection of trypanotolerant animals based on infection criteria.     

Effect of mating behavior on luteinizing hormone-releasing hormone release in female rabbits as monitored with push-pull cannulae

To examine the effect of mating behavior on luteinizing hormone-releasing hormone (LHRH) release, intact New Zealand female rabbits were implanted with push-pull cannulae (PPC) aimed at the tuberal region of the hypothalamus and perfused with modified Krebs-Ringer phosphate medium at 11-13 microliters/min. In the mating experiments, does (n = 10) were initially perfused for a control period of 60-170 min followed by a mating period (100-160 min) which included the introduction of the male rabbit for an average time period of 30 min. Two groups of LHRH release patterns were observed: positive and negative responders. In the positive LHRH responders (n = 5), a clear rapid increase in LHRH release following mounting by the male occurred with a significant increase in the mean LHRH release (1.83 +/- 0.33 to 3.27 +/- 0.80 pg/10 min, p less than 0.040), in the mean LHRH amplitude (1.97 +/- 0.46 to 4.33 +/- 1.29 pg, p less than 0.022) and in the amplitude of the largest LHRH pulse (2.13 +/- 0.43 to 7.58 +/- 3.65 pg, p less than 0.022). In the negative LHRH responders (n = 5), no changes in LHRH release were detected although all rabbits ovulated, with some becoming pregnant. It appears from histological analysis that the difference between these two patterns of responses following mating are due to different cannula placements. In the positive responders, the tip of the PPC was localized in the tuberal region whereas in the negative responders, the placements were more dorsal and, in some cases, anterior.(ABSTRACT TRUNCATED AT 250 WORDS)