Frequency-dependent prey-selection of predacious water bugs on Armigeres subalbatus immatures.

BACKGROUND & OBJECTIVES: The predatory behaviour with reference to the frequency-dependent prey-selection of the water bugs Sphaerodema annulatum Fabricius and S. rusticum Fabricius was studied in the laboratory using the IV instar larvae and pupae of Armigeres subalbatus as prey to ascertain their efficacy as predator of mosquito immatures. METHODS: Field collected adult morphs of the water bugs were allowed to predate on larvae and pupae provided in different ratios and densities as per the model of Greenwood and Elton' for a fixed time period. The data obtained on their predation rate were analysed with respect to the model parameters, lnV--the frequency independent component and b--the frequency dependent component of selection. RESULTS: It was found that the prey-selection was dependent on the relative numbers of prey available, favouring apostatic selection. The b values and lnV values for S. annulatum were 0.54 +/- 0.01 and 0.92 +/- 1.04 respectively whereas the corresponding values for S. rusticum were 0.71 +/- 0.03 and 0.17 +/- 1.57 respectively. INTERPRETATION & CONCLUSION: The selection of preys by the water bugs was dependent on the relative number of the prey forms and thus they are expected to predate on the form more abundant in a heterogeneous prey population and adversely affect the adult emergence.

Incidence and prognostic significance of right bundle branch block complicating acute myocardial infarction.

The incidence and hospital courseofacute myocardial infarction wereobserved among randomly selected 560 patients. The mean age of the patients was 53 +/- 6.67 years with male-female ratio 2.6:1. The incidence of right bundle branch block (RBBB) was 15% (84 out of 560 patients). New RBBB, old RBBB and RBBB of indeterminate age were observed in 33 (39.25%), 23 (27.40%) and 28 (33.25%) cases respectively. RBBB was isolated in 50 (60%) cases and bi-fascicular in remaining 34 (40%) cases. The rate of use of thrombolytic was greater in RBBB group than non-RBBB group (52% vs 30.67%, P < 0.05). The complications were more frequently observed in patients with RBBB: in-hospital mortality, 27.40% vs 10.90% (P < 0.01); use of temporary pacemaker, 15% vs 9% (P < 0.05); and heart failure, 50% vs 35% (P < 0.05). In sub-group analysis, in-hospital mortality rate was higher among bi-fascicular group than isolated RBBB group (P < 0.05). Thus it appeared from the results that the incidence of RBBB is relatively common i.e. 15% over all (84 out of 560) and 5.90% new (33 out of 560) and despite greater use of thrombolytics, some specific in-hospital complications were significantly higher in patients with RBBB than without, RBBB.

Incidence of spontaneous echocontrast in left atrium in mitral stenosis detected by transoesophageal echo cardiography and related factors.

The incidence of left atrial (LA) spontaneous echo contrast (SEC) and the clinical and echocardiographic variables related to it were prospectively evaluated in a series of 60 patients with mitral stenosis (MS) undergoing transoesophageal echocardiography (TEE) with a 5 MHz multiplane transducer. LA-SEC was found in 39 patients (65%) employing TEE. Statistical analysis showed a significant relationship between the presence of SEC and MS without mitral regurgitation (MR) (P < 0.05), MS with < or = MR grade II (P < 0.05), atrial fibrillation (P < 0.001) and increased left atrial dimension (P < 0.05). Age, sex, mitral valve area and ejection fraction did not show any positive association (P > 0.05). Thus, it is concluded that LA-SEC is a common finding observed in approximately 65% of MS patients undergoing TEE and associated with conditions favouring stasis of left atrial blood.

Clinical significance of IgE in bronchial asthma.

Total mean serum IgE levels of 63 patients (aged 16-49 years) suffering from bronchial asthma and 64 control subjects (aged 19-40 years) were estimated by RIA method. Mean serum IgE level of patients and control subjects was 1132 +/- 643 units/ml and 43 +/- 26 units/ml respectively. The difference between the two values was statistically significant (p less than 0.001). Four per cent of the patients had serum IgE levels within normal limits. No significant correlation was found between mean serum IgE level of the patients and the duration of the disease. Differences in mean serum IgE level of male and female patients and control subjects was not statistically significant. The mean serum IgE level of patients in the age group of 21-40 years was highest (F = 1.33, p less than 0.05). Significantly elevated levels of serum IgE were observed in patients with both personal and family history of atopic disease in comparison to patients with only personal or family history only (p less than 0.05). As such the estimated raised level of IgE was significant in view of the severity of atopic asthma.