Technique and ground reaction forces in the back handspring.

The ground reaction forces at the hand that produced compression forces and varus/valgus moments at the elbow joint during the double-arm support phase of the back handspring were studied. The relationship of technique, namely elbow joint flexion, to these forces were also studied. Compression forces and forces producing valgus moments have been implicated in overuse injuries to the elbow joint. Video and force plate analysis of six young female gymnasts showed that 1) the elbow joint flexed during the double-arm support phase, and 2) the reaction forces at the hand produced large compression forces (an average of 2.37 times body weight) and sizable valgus moments at the elbow (an average of 0.03 times body weight times body height). The combination of these forces may contribute to the occurrence of lateral compression injuries of the elbow joint (e.g., osteochondritis dissecans of the capitellum). Correlations of measures of elbow angle and measures of reaction force showed that large elbow flexions may protect the elbow from large valgus moments.     

Blood donation and transfusion practices: the 1990 American Association of Blood Banks Institutional Membership Questionnaire

Responses to the 1990 American Association of Blood Banks (AABB) Institutional Membership Questionnaire were submitted by 2126 regional blood centers, hospital-based blood banks, and transfusion facilities. Data from 2117 of these facilities were considered to be valid. The questionnaire included information on blood donor demographics, number of units collected, and collection procedures; services performed; usage of blood components; and transfusion-transmitted diseases reported during 1989. Institutional members collected 7.4 million whole blood units, of which 90.8 percent were donated for allogeneic use, 6.0 percent were donated for autologous use, and 3.2 percent were donated for directed use. Approximately 630,546 allogeneic and directed-use blood donors were deferred, most often for low hemoglobin or hematocrit values. Approximately 225,205 full allogeneic and directed-donor units were discarded, primarily for elevated alanine aminotransferase levels or the presence of hepatitis B core antibody. The 14.3 million transfused components included 56.7 percent red cell-containing components, 27.4 percent platelets, 11 percent fresh-frozen plasma, and 4.8 percent cryoprecipitate. Institutional members reported 1397 cases of transfusion-associated hepatitis. In this group, 921 patients were tested for hepatitis B surface antigen after the transfusion; 339 (36.8%) were found to be hepatitis B surface antigen positive. The AABB Institutional Questionnaire results provide recent data on blood donor and transfusion-related activities that are vital to the evaluation of current transfusion medicine practices.     

Severe paroxysmal hypertension induced by a subconscious Valsalva-like manoeuvres

We describe the case history of a 32 year old male with severe paroxysmal hypertensive spikes when there was an increase in diastolic blood pressure to 150–200 mmHg. These spikes occurred during rest and especially during modest exercise. They were associated with headache and dyspnoea and were resistant to antihypertensive medication. After 5 years of observations and investigations he underwent further 24-h intra-arterial blood pressure monitoring and physiological testing. The 24-h blood pressure profile was near normal at rest. The observed hypertensive spikes seemed to be induced by involuntary Valsalva-like manoeuvres. This had not been detected previously by the investigators and the patient was unaware of inducing these manoeuvres.     

TESTICULAR TORSION

A retrospective review of 80 patients who underwent scrotal exploration for presumed testicular torsion is presented. Of these, 67 patients were found to have torsion, and the testicular loss rate was 51%. Patients who experienced delays in scrotal exploration of more than 24 h from onset of symptoms had a testicular loss rate of 71 %. These delays arose from both hesitation in seeking medical treatment and misdiagnoses. It is emphasized that an acute scrotum in a child or in an adolescent should be explored early to exclude torsion.     

The febrile stress of routine vaccination does not increase central apnoea in normal infants

Abstract We tested the hypothesis that the febrile stress of routine vaccination would increase central apnoea in normal infants. Twenty-one normal infants had continuous overnight breathing and temperature recorded at home, before and after 58 routine vaccination episodes. Central apnoea, of at least 5 sec duration, was detected by computer algorithm and confirmed by human inspection. The longest recorded apnoea was 16 sec ( n = 1) during 3629 h of sleep. Overnight rectal temperature increased after vaccination (median 0.52°C, 95% CI 0.40, 0.65). Apnoea density reduced on 46/53 vaccination nights (median -29%, 95% CI -20, -37) followed by an increase on subsequent nights (median +10%, 95% CI +1%, +21%). Overall, apnoea density was similar during the 3 nights preceding and 4 nights following vaccination (median +1%, 95% CI +9,-6). The febrile stress of routine vaccination did not increase central apnoea in normal infants.     

Altered cell trafficking in mesenteric lymphoid tissue following syngeneic heterotopic small bowel transplantation in rodents.

These data indicate that in rat heterotopic syngeneic SBT, the venous drainage system of the graft has profound effects on cell recovery in the gut-associated lymphoid tissue of both graft and host. Depending on the functional status of the same lymphoid tissue (Gorezynski, personal communication, 1992) one could thus anticipate significant perturbation of host-antigraft (and GVH) reactivity in allogeneic situations according to the venous drainage used. The mechanism(s) responsible for these effects have not been investigated. However, one testable hypothesis is that (a) factor(s) from the gut can control lymphoid recirculation within the mesenteric lymphoid tissue, and that this (these) factor(s) are absorbed under normal circumstances by hepatic tissue.     

2-Acetylaminofluorene inhibits the activation of immune responses by blocking cell cycle progression at G1 phase

 2-Acetylaminofluorene (AAF) inhibited in a dose dependent manner mouse spleen cell blastogene sis in response to phorbol 12-myristate 13-acetate (PMA)/Ionomycin (Io) activation, the T-cell lectin, concanavalin A (Con A), and following stimulation by alloantigens as measured by the mixed lymphocyte response (MLR). AAF also markedly suppressed the T-cell dependent antibody forming cell (AFC) response to sRBC. AAF was most inhibitory on both the sRBC IgM AFC response and Con A stimulated proliferation when added during the first 24 h following initiation of culture. Direct addition of high concentrations of AAF (100 μM) to spleen cell cultures at 48 h following Con A stimulation produced a very modest inhibition (<20%) of T-cell proliferation as compared to 90% when added at the time cultures were initiated. Similarly, AAF (75 and 100 μM) produced a greater than 80% inhibition of the in vitro AFC response when spleen cells were sensitized with antigen in presence of AAF. In contrast, no inhibition of the IgM AFC response was produced when AAF (75 μM) was added to spleen cell cultures 48 or 72 h after antigen sensitization. Con A-triggered cell-cycle progression was attenuated at the G₁ stage by the addition of AAF (50 and 100 μM) with no inhibition of S to G₂/M phase transition. These results suggest that the mechanism of AAF-mediated immune suppression is through a blockade of cell cycle progression from G₁ to S phase. Received: 5 July 1994/Accepted: 19 October 1994     

In vivo load sharing among the quadriceps components.

Knee extension is always performed with coordinated contractions of multiple quadriceps muscle components; however, how the load is shared among them under normal and pathological conditions is unclear. We hypothesized that: the absolute moment generated by each quadriceps component increases with the total knee extension moment; the relative contribution and its dependence on the total knee extension moment are different for different quadriceps components; and the centrally located large vastus intermedius (VI) is favored by the central nervous system at low levels of activation. Electrical stimulation was used to activate each quadriceps component selectively in six human subjects. The relationship between the knee extension moment generated by an individual quadriceps component and the corresponding compound muscular action potential (M-wave) over various contraction levels was established for each quadriceps component. This relationship was used to calibrate the corresponding EMG signal and determine load sharing among quadriceps components during submaximal isometric voluntary knee extension. The VI contributed the most (51.8-39.6%) and vastus medialis the least (9.5-12.2%) to knee extension moment (P<0.05). As the knee extension moment increased, the relative contribution of the VI decreased (P=0.017) while the relation contribution of the vastus lateralis and medialis increased (P相似文献   

Persistent diarrhea associated with AIDS

Chronic diarrhea and wasting are very common manifestations of AIDS in adults in developing countries. Etiologic studies show that protozoa (including Cryptosporidium parvum, Isospora belli , and Enterocytozoon bieniusi ) and Mycobacterium avium-intracellulara are the most frequently identified pathogens. Limited data in children suggest that common enteric pathogens are equally as likely in HIV⁺ and HIV^- babies. Preliminary analysis of an ongoing longitudinal study of 469 babies born to mothers with known HIV serostatus in Kinshasa, Zaire, reveals progression of acute to persistent diarrhea is six times greater in HIV⁺ compared to HIV^- babies, and 3.5 times greater in HIV^- babies born of HIV⁺ mothers in comparison to HIV^- babies with HIV^- mothers. HIV⁺ babies were also at greater risk than HIV^- babies to have recurrent episodes of diarrhea (RR = 2.3). Fifty percent of the deaths were due to acute or persistent diarrhea, and were strongly associated with HIV infection. Efforts to improve child survival in AIDS infected populations will need to address HIV infections in both mothers and infants.