Effect of two different sized hand paddles on the front crawl stroke kinematics

AIM: The purpose of the present study was to determine the effect of two different sized hand paddles on the three-dimensional underwater stroke pattern of front crawl swimming at a fixed stroke rate. METHODS: Nine male adolescent competitive freestyle swimmers participated in the study. Each subject swam a series of 25 m trials at a constant stroke rate, without and with hand paddles of two different cross sectional areas (small paddles: 116 cm(2), large paddles: 311 cm(2)). An acoustic metronome connected with a sound amplifier was used to help the subject keep the stroke rate constant. Stroke rate was calculated for each subject using the time for 3 complete right arm stroke cycles. The underwater motion of each subject's right arm was filmed using two S-VHS cameras, operating at 60 fields/s, which were located behind two underwater viewing windows. The spatial coordinates of selected points on the right arm and the hip were calculated using the DLT procedure with 30 control points and after the digital filtering of the raw data with a cut-off frequency of 6 Hz, the hand's linear displacements and velocities, as well as the mean swimming velocity, were calculated. Moreover, the displacement of the hip in the direction of propulsion, from the right hand's entry to the next entry of the same hand, was calculated in order to determine the stroke length. For the statistical treatment of the data the analysis of variance for dependent samples was used. RESULTS: The analysis of the data revealed that when hand paddles were worn, the stroke length (F(2,16)=10.329; P<0.05) and the mean swimming velocity (F(2),16=5.076; P<0.05) were significantly increased, while the temporal characteristics of the underwater stroke and the displacement of the hand were not significantly altered. On the other hand, the peak backward hand speeds during the insweep (F(2,16)=4.794; P<0.05) and the push phase (F(2,16)=5.827; P<0.05) were greatly reduced. These modifications were greater when large paddles were worn. CONCLUSIONS: From the results of the present study it was concluded that the movement pattern was not significantly modified when swimmers swam with hand paddles, at a constant stroke rate. However, large hand paddles caused a decrease in their hand velocities during the underwater stroke.     

Reconstruction accuracy in underwater three-dimensional kinematic analysis

Accuracy of kinematic data is of decisive importance in motion analysis particularly when they are to be used for the calculation of kinetic parameters, like the propulsive forces in swimming. The present study investigated the accuracy of underwater three-dimensional (3-D) kinematic analysis using periscope systems and calibration volumes with different size. Two analogue cameras (60Hz) were used to record the images, along with two stationary periscope systems for the underwater recordings. The calibration of the recording space was performed using two different-sized calibration frames. The reconstruction accuracy was determined in static and dynamic conditions, both under water and out of the water. In static conditions, the reconstruction accuracy was determined by calculating the root mean square (RMS) error for the reconstruction of eight validation points on the calibration frames, and in dynamic conditions it was determined by the percentage of RMS error of the reconstructed length of a moving rod. The results revealed that in static conditions the RMS error was greater during underwater analysis, due to refraction, and it was increased particularly in the longitudinal axis as the dimensions of the calibration volume were increased. The reconstruction errors observed during underwater recordings with both calibration volumes (transverse axis, 1.61-2.35mm; longitudinal, 2.99-4.64mm; vertical, 2.83-2.59mm) may be considered suitable for three-dimensional kinematic analysis of swimming.     

Monoclonal antibody therapy of chronic lymphocytic leukemia.

Chemotherapeutic approaches during the last decade have failed to result in major advances in the outcome of patients with chronic lymphocytic leukemia (CLL). The recent availability of an increasing number of active monoclonal antibodies, immunotoxins, and radioimmunoconjugates (RICs) has stimulated considerable interest in clinical research in CLL. Alemtuzumab was the first antibody approved for CLL on the basis of responses in one third of patients with advanced disease. However, infusion reactions and immunosuppression with opportunistic infections present a challenge that may be overcome with altered schedules and routes of administration. Rituximab has limited activity as a single agent in patients relapsed or refractory after prior chemotherapy; however, response rates seem to be higher in previously untreated patients. More importantly, combinations with chemotherapy drugs such as fludarabine are showing promise in early trials. Newer antibodies in development as single agents and in combinations include apolizumab (Hu1D10), a humanized antibody against an epitope of HLA-DR, and IDEC-152, a primatized anti-CD23 antibody. BL22, an immunotoxin with impressive activity in hairy cell leukemia, is in phase II trials in CLL as well. The safe use of RICs is complicated by the elevated peripheral blood B-cell count, and the extent of bone marrow involvement in CLL; studies will explore the use of agents to eliminate malignant cells from the bone marrow before RIC therapy. It is hoped that the rational development of combinations of the various promising antibodies with chemotherapy and each other will lead to more effective approaches for patients with CLL.     

Visual evoked potentials in hypothyroid and hyperthyroid patients before and after achievement of euthyroidism.

Thyroid hormone deficiency is frequently associated with central nervous system (CNS) disturbances such as mental retardation, convulsions, coma etc. Studies of quantitative changes in CNS in hypo- or hyperthyroidism are scarce. Evoked potentials is a good method of assessing the electrical response of the brain to different (visual, acoustic, somatosensory) stimuli and has been used extensively in the study of brain disturbances and to a lesser degree in metabolic diseases. We studied the visual evoked potentials (latency and amplitude) in 12 patients with hyperthyroidism and 15 patients with hypothyroidism, before treatment and after they became euthyroid. Four of the hyperthyroids (33%) had abnormally prolonged (> 104 msec) latencies before therapy. Two of them had clinical exophthalmos. No change was observed after euthyroidism was achieved. On the contrary 7 out of 15 (47%) hypothyroids had abnormally prolonged latencies which became normal in 4 when euthyroidism was achieved. Amplitude was lower than normal in 6 and became normal only in one of them after treatment. None of the hyperthyroid patients had amplitude changes. In conclusion, hypothyroid patients may have changes in the amplitude and/or the latency of visual evoked potentials which are reversible to a great extent with thyroxine. Evoked potentials is another method of studying in humans the metabolic effects of thyroxine deficiency in CNS.     

Novel therapies for chronic lymphocytic leukemia

New therapies for chronic lymphocytic leukemia (CLL) are moving away from non-specific cytotoxic to more targeted approaches. The monoclonal antibody alemtuzumab induces responses in 33% to 43% of patients with relapsed or refractory disease, with 2-5% CR. Side effects include infusional reactions as well as immunosuppressive effects. Rituximab has limited activity in relapsed refractory patients, but response rates are comparable to follicular non-Hodgkin's lymphoma in untreated patients. Other antibodies in early phases of development include anti-CD23 [IDEC-152], anti-CD22 [epratuzumab], Hu1D10 [apolizumab], and anti-CD80 [anti-B7, IDEC-114]. Other agents that are being studied include denileukin diftitox fusion protein (Ontak), and bcl-2 antisense [G3139, Genasense]. The mechanism of action of the new drugs and their role in CLL, as well as the emergence of new prognostic markers are discussed.     

Comparison of outcomes of percutaneous coronary intervention of ostial versus nonostial narrowing of the major epicardial coronary arteries

Outcomes of percutaneous coronary intervention (PCI) of the ostia of the major epicardial coronary arteries in the modern era of stenting have not been clearly defined. We evaluated data from all PCIs performed from 1998 to 2001 in the proximal segments of the major epicardial coronary arteries entered into a large cardiac database and compared ostial with nonostial PCI outcomes. Of 2,484 patients who underwent PCI of a proximal coronary artery (left anterior descending, left circumflex, or right coronary), 223 patients had ostial narrowing and 2,261 patients had proximal, nonostial narrowing. Baseline characteristics were similar between the 2 groups, except that patients with ostial narrowing tended to be older and have shorter narrowings than did patients with nonostial narrowings. Stenting occurred in 89% of all patients and was similar in patients with ostial or nonostial narrowings. Procedural success was the same for ostial and nonostial PCI (96% vs 95%, p = 0.95). One-year event-free survival rate was lower in patients who underwent ostial PCI (69% vs 80%, p = 0.0019), largely due to a greater need for repeat PCI (19% vs 10%, p <0.0001). Multivariate analysis showed that ostial location, age, angina class, and number of diseased vessels were independent predictors of the occurrence of cardiac events. PCI of ostial narrowings of the major epicardial coronary arteries was relatively safe. However, at 1 year, patients who underwent ostial PCI had an increased rate of repeat revascularization compared with patients who underwent nonostial, proximal PCI.     

Familial nemaline myopathy: case reports.

Two siblings of two generations in the same family with nemaline myopathy are described. The disease affects all skeletal muscles, especially the facial muscles, producing a typical facial appearance. The diagnosis was made by light microscopy of histologically stained sections of muscle biopsy. The disease in our patients seems to be transmitted in an autosomal dominant manner. The purpose of this article is to emphasize the importance of recognition of the facial appearance by maxillofacial surgeons and the appropriate referral of patients for further neurologic examination.     

Intrapancreatic true arterial aneurysm mimicking pancreatic tumor

Journal of Gastrointestinal Surgery -