[Comparison of acute sports injury between recreational skiers and skiers].

OBJECTIVE: To compare and analyze the difference between the injuries of recreational skiers in public ski resorts and those of skiing athletes in official competitions, and to explore the suggestions of medical insurance for these two types of skiers. METHODS: The injury data of recreational skiers in Chongli District, Zhangjiakou City, Hebei Province during 2018-2019 and 2019-2020 snow seasons, and the injury data of skiers in two official international skiing competitions during 2019-2020 snow season and domestic test events in Chongli District of 2021 Winter Olympic Games were analyzed retrospectively, and the similarities and differences were compared. RESULTS: A total of 1 187 injuries occurred to recreational skiers in the two public ski resorts during the 2018-2019 snow season, with an injury rate of 0.3%.There were 1 277 injury sites in total, and the most frequent injury sites were head and neck (230 cases, 18.0%), followed by knee joint (204 cases, 16.0%) and lower extremity (131 cases, 10.3%). Thirty-one skiers were injured in the two official international skiing competitions in the 2019-2020 and 2020-2021 snow season, and in the domestic test competitions in the 2021 Winter Olympic Games, and the injury rates were 11.5%, 17.2% and 12.0%, respectively. There were 37 injury sites in total, among which 11 (29.7%) were in the head and neck, followed by 6 (16.2%) in the knee joint and 5 (13.6%) in the chest, rib and abdomen. CONCLUSION: In order to better guarantee the safety of skiers and timely provide corresponding medical help, safety facilities and technical guidance should be added to the snow resort for leisure skiing, and medical stations should be set up in the snow resort. As the formal ski racing for skiing athletes during the game has 30 to 80 times higher injury ratesthan recreational skiers, and compared with the recreational skiing, head and neck injury rate is higher, and the damage is much heavier, more complete first aid facilities and experienced medical workers are, needed so the field should be equipped with the circuit inside the quantities, track fixed outside the clinic, surrounding referral hospitals set up trauma centers to provide athletes with more timely medical care.

Mutagenic effect of gold nanoparticles in the micronucleus assay.

Mutagenic activity of gold nanoparticles of different sizes were studied by micronucleus assay. Karyological analysis was performed and the count of micronucleoli in interphase bone marrow polychromatic erythrocytes in white outbred rats was determined. The animals orally received gold nanoparticles 16 and 55 nm in diameter and gold nanoshells 160 nm in diameter once a day for 7 days in a dose of 0.25 mg gold/kg. To ensure stability and biocompatibility, the surface of nanoparticles was functionalized with polyethylene glycol molecules. There were no significant differences in the number of micronucleoli in comparison with the control group, which suggests that gold nanoparticles of the specified size administered orally in the specified doses do not exhibit mutagenic activity.

Inhibition of reduced glutathione synthesis by cyanobacterial alkaloid cylindrospermopsin in cultured rat hepatocytes.

Cylindrospermopsin (CY) is a naturally occurring alkaloid produced by the cyanobacterium Cylindrospermopsis raciborskii, which has been linked to an outbreak of hepatoenteritis in humans. We previously showed that CY is cytotoxic to primary cultures of rat hepatocytes and that CY lowers cell reduced glutathione (GSH) at nontoxic doses. Lower cell GSH also potentiates CY-induced cytotoxicity (Runnegar et al., Biochem Biophys Res Commun 201: 235-241, 1994). Our current work examined the mechanism of the fall in cell GSH induced by CY. We excluded several possible explanations for the loss in GSH, namely increased formation of oxidized glutathione (GSSG), increased GSH efflux, hidden forms of GSH, decreased GSH precursor availability, or decreased cellular ATP level. To address whether the fall in GSH was due to decreased GSH synthesis or increased GSH consumption, we examined the rate of fall in total GSH after 5 mM buthionine sulfoximine (BSO, an irreversible inhibitor of GSH synthesis) treatment. The rates of fall in total GSH (nmol/10(6) cells/hr) were 8.2 +/- 2.5, 6.0 +/- 1.7 and 5.9 +/- 1.3 for control, 2.5 microM and 5 microM CY-pretreated cells, respectively. This suggests that the fall in GSH induced by CY was due to the inhibition of GSH synthesis rather than increased consumption, because in the latter case the rate of fall in GSH would have been accelerated by CY pretreatment. Furthermore, excess GSH precursor (20 mM N-acetylcysteine), which supported GSH synthesis in control cells, did not prevent the fall in GSH or toxicity induced by CY. Treatment of cells with the cytochrome P450 inhibitor alpha-naphthoflavone protected partially from CY-mediated toxicity and from the fall in cell GSH. Thus, it is likely that cytochrome P450 is involved in the metabolism of CY, and the metabolite(s) that is generated may be more toxic and/or potent in inhibiting GSH synthesis. Inhibition of GSH synthesis is most likely an important factor in the cytotoxicity of CY.

Electrocardiographic changes in amitriptyline poisoning.

In imipramine and amitriptyline poisoning the electrocardiographic abnormalities comprise arrhythmias, widening of the QRS complex, and marked changes in die S-T segment. These features were found to be of value in the differential diagnosis of unknown poisoning. The unusual configuration of qR with raised S-T segment in V1, simulating myocardial infarction, was seen in one of our patients and has been noted in four cases reported by other workers.

The changing prevalence and pattern of acute rheumatic fever and rheumatic heart disease in Hong Kong--(1968-1978).

The occurrence and pattern of rheumatic fever and rheumatic heart disease in Hong Kong in the years 1968 to 1978 were surveyed. The incidence of rheumatic fever in hospitals had decreased by four-fifths in the past 10 years. Rheumatic fever nowadays still predominantly affects children and younger adults, but middle-aged patients may also be affected. There are a slight female dominance (1.3 to 1) and a relative predominance of patients from urban areas. A less severe form of manifestation in adult patients is encountered nowadays. Carditis was the dominant feature in 1968, but joint involvement was more common in recent years. Rheumatic nodules, chorea or erythema marginatum remained uncommon throughout the years. Only 49% of cases satisfied the revised Jones criteria (1965). In comparison, chronic rheumatic heart disease still remained prevalent, with a slower trend of decreasing prevalence. It accounted for (36 to 50%) of total cardiac admissions. The mitral valve was involved in (82.7 to 91.7%), aortic valve in (15.5 to 36.3%), while involvement of tricuspid or pulmonary valve was relatively uncommon. The socio-economic implication of this changing trend was analysed, and the problem encountered in diagnosing rheumatic fever discussed.

Translocating the aberrant right subclavian artery in dysphagia lusoria.

A case of dysphagia lusoria with unusual associated symptoms in an adult is presented. The condition was treated by division of the aberrant right subclavian artery at its origin through a median sternotomy and translocating the distal subclavian artery to the aortic arch with an interposition Dacron graft. All the reported techniques of dividing and transposing the aberrant right subclavian artery in dysphagia lusoria are reviewed and discussed.

Coronary artery to left ventricle fistulas: echocardiographic features.

The echocardiographic features of a coronary artery fistula that drains into the left ventricle were described in two patients. The clinical picture mimicked moderate to severe aortic insufficiency; however, M-mode echocardiogram revealed unusual features. Diastolic fluttering of the anterior mitral leaflet and the septum was absent in the first patient, while the second patient had marked diastolic fluttering of the posterior mitral leaflet and the left ventricular wall at the atrioventricular junction. In both, the coronary artery fistula could be visualized by cross-sectional echocardiography. Contrast echocardiography performed during cardiac catheterization in the second patient demonstrated that the diastolic fluttering of the posterior mitral leaflet was related to the jetting of blood from the coronary artery fistula.

In vivo and in vitro binding of microcystin to protein phosphatases 1 and 2A.

The hepatotoxic microcystins (Mcyst) are potent inhibitors of the ser/thr protein phosphatases (PP1 and PP2A) with IC50's of 0.1-1.0 nM. Mcyst and other PP inhibitors like okadaic acid or calyculin A interact with the C-terminal region of PP1 and PP2A. Using [125I]-Mcyst and antibodies specific for PP1 and PP2A, we show by immunoprecipitation and autoradiography, that in hepatocytes Mcyst forms secondary covalent bonds with both PP1 and PP2A catalytic subunits. We demonstrate that the bond resulted from the reaction between the electrophilic alpha, beta unsaturated carbonyl of the methyldehydroalanine residue of Mcyst and the thiol of Cys 273 located in the C-terminal of PP1 (Cys 266 in PP2A), since site-directed mutagenesis of Cys 273 to Ala in PP1 alpha led to complete loss of ability for the formation of a covalent Mcyst-PP1 adduct.

Experience with outlet strut fracture of the Björk-Shiley convexoconcave mitral valve prosthesis.

Within a period of 15 months, we encountered five patients with outlet strut fracture of the Björk-Shiley convexoconcave mitral valve prosthesis. All of the patients had acute failure of the left side of the heart and pulmonary edema. The diagnosis was made by review of the chest roentgenogram which showed features of pulmonary edema; both the outlet strut and the tilting disc were missing from the mitral prosthesis. The "missing" components might be found in the left side of the heart or in the course of the thoracic aorta. Emergency reoperation was carried out on three patients, and there were two survivors. It is essential to recognize this potentially fatal complication and undertake immediate surgical intervention. We performed the original valvular replacement operations in four of the five patients. The probability of outlet strut fracture occurring in our series of 237 patients with a Björk-Shiley convexoconcave mitral valve prosthesis is 1.69%, or 0.076 per 100 patient months.

The role of glutathione in the toxicity of a novel cyanobacterial alkaloid cylindrospermopsin in cultured rat hepatocytes.

Cylindrospermopsin (CY) is a newly isolated alkaloid produced by the cyanobacterium Cylindrospermopsis raciborskii, which has been linked to an outbreak of hepatoenteritis in man. The current work examined the suitability of primary cultures of rat hepatocytes as an in vitro model for studying the cytotoxicity of CY. We found that CY (3.3-5.0 microM) caused significant cell death (40-67% of cells by LDH release) in cultured hepatocytes after 18 hr incubation. While investigating possible mechanisms for CY toxicity, we found that lower, nontoxic doses of CY (1.6-2.5 microM) decreased cell glutathione (GSH) to about 50% of control. For toxic doses (5 microM), the loss of GSH preceded the onset of toxicity by six hr. Lowering cell GSH predisposed cells to CY toxicity. In conclusion, cultured hepatocytes are a suitable model for studies of CY cytotoxicity and GSH is involved in the detoxification of CY.

High level expression and secretion of Fc-X fusion proteins in mammalian cells.

We have developed a general expression system that enhances the production and secretion of proteins in mammalian cells. The protein of interest is expressed as a fusion to a signal peptide and the Fc fragment of immunoglobulin as the N-terminal fusion partner, which can direct the cellular processes into expressing and secreting high levels of many different types of proteins. These include secretory proteins, enzymes and soluble domains of membrane proteins, as well as nuclear and regulatory proteins. Typical expression levels of these proteins from stable cell lines ranged from several to 100 microg/ml in conditioned media. The Fc domain helps to solubilize hydrophobic proteins and provides a handle for easy detection and purification of the fusion proteins; and it can be cleaved off by treatment with protease if desired.