Effect of diazepam on digitalis-induced ventricular arrhythmias in the cat

The capacity of diazepam to counteract cardiac arrhythmias was studied in barbiturate-anesthetized cats treated with digitalis (i.e., deslanoside, 25 μg/kg given every 15 min iv). Diazepam dissolved in commercial propylene glycol solvent was administered in repeated doses of 10 mg iv at approximately 45-sec intervals to five animals exhibiting deslanoside-induced ventricular arrhythmias. Conversion of the arrhythmia to sinus rhythm was observed in two animals, while development of more serious rhythm changes was observed in the other three animals. One explanation for the deleterious effect seen with diazepam in the three animals is that the solvent itself may produce significant cardiocirculatory changes. To test this possibility, seven animals were intoxicated with deslanoside and the diazepam solvent was administered in doses of 1.0 ml every 45 sec until a total dose of 5.0 ml was given. In each animal, the administration of the solvent was associated with the development of more serious rhythm changes. Ventricular fibrillation (VF) developed 10.8 ± 1.6 min after the onset of deslanoside-induced ventricular tachycardia (VT). The corresponding time interval between deslanoside-induced VT and VF was 26.7 ± 5.0 min when no solvent was administered. These results indicate that propylene glycol solvent is deleterious to cardiac rhythm and should not be employed as a vehicle for antiarrhythmic drugs.     

Effect of bretylium on cardiovascular changes induced by coronary occlusion in the cat.

The influence of bretylium pretreatment on the heart rate, blood pressure, contractile force and cardiac rhythm changes produced by occlusion of the anterior descending coronary artery was evaluated in chloralose-anesthetized cats. Bretylium pretreatment shortened the duration of the ventricular arrhythmia. This drug however had no effect on the other cardiovascular changes evoked by coronary occlusion. These results suggest that the sympathetic nervous system has a role in maintaining electrical instability after experimentally induced myocardial infarction.     

T-Cell lymphoma model for the analysis of interleukin 1-mediated T-cell activation.

Several laboratories have recently demonstrated that the requirement for macrophages in mitogen-induced production of murine T-cell interleukin 2 (IL-2; formerly referred to as "T-cell growth factor") could be circumvented by using the macrophage-derived peptide interleukin 1 (IL-1; formerly referred to as "lymphocyte-activating factor"). Using two cloned T-cell lymphomas, we investigated the mechanism through which IL-1 exerted its effect on IL-2 production. One of the cell lines used (LBRM-33 5A4) produces large concentrations of IL-2 upon mitogen stimulation, whereas the second (LBRM-33 1A5) is incapable of producing IL-2 in response to mitogen. It was observed that addition of purified IL-1 to nonproducer 1A5 cells converted them to a state in which subsequent mitogen stimulation triggered production of IL-2. The concentration of IL-2 produced by IL-1 treated 1A5 cells was equivalent in magnitude to that generated by mitogen-stimulated 5A4 cells (500-1000 units/ml, or approximately 1000 times the concentration of IL-2 contained in conventional preparations of murine mitogen-conditioned medium). The observations that (i) brief exposure to IL-1 was sufficient for 1A5 cell conversion to IL-2 production and (ii) IL-1 could actively be absorbed from culture medium by live or fixed 1A5 cells led us to propose the existence of IL-1 receptors on responsive 1A5 cells. On the basis of these experiments, we have postulated that IL-1 mediates its effect on immune reactivity (enhancement of thymocyte mitogenesis and induction of antibody and cytotoxic T cell responses) by maturation of a subset of immature T cells to the point where they are capable of IL-2 production. Subsequent release of IL-2 after ligand activation allows for clonal expansion of activated T cells which mediate particular effector functions.     

Local Anaesthesia for Fiberoptic Intubation : A Comparison of Three Techniques

Background

The successful conduct of fiberoptic aided intubation is dependent upon effective local anaesthesia. The aim of the study was to compare three different methods of anaesthetizing the airway.

Methods

60 adult patients (American Society of Anaesthesiologists status I-III and Mallampati class III & IV), scheduled for elective surgery, received sedation followed by spraying of the nares and posterior pharyngeal wall with 4% lignocaine. Thereafter the patients received 4 ml of 4% lignocaine either by transtracheal injection (n=20, group A), via intubating fiberscope (Pentax F1-10P2) using ‘spray as you go’ technique (n=20, group B) or by nebulizer (Devilbiss 5610W) 20 min before intubation, (n=20, group C). Patients were asked to score the procedure using visual analog scale (VAS) and severity scores. Episodes of coughing, choking, stridor, extra / total local anaesthetic used and intubation times were recorded. Patients were monitored continuously for vital parameters.

Results

Group B patients showed better VAS scores with shorter intubation times and had a lower incidence of coughing and choking. The endoscopists’ VAS scores also showed a preference for group B.

Conclusion

In conclusion the ‘spray as you go’ technique was safe, provided effective local anaesthesia and was preferred by both patients and endoscopists.Key Words: Awake intubation, Difficult airway, Fiberoptic intubation     

Inadequate treatment of symptomatic breast cancer

BACKGROUND: Early trials that compared breast and axillary treatments showed differing recurrence rates without significant differences in survival. Consequently, there was a wide range of opinion and practice in the management of breast cancer. The present study explored this variability in surgical management to determine the impact of breast and axillary treatment on recurrence and survival. METHODS: The records of 2776 women with histologically confirmed invasive breast cancer diagnosed between 1986 and 1991 were reviewed. The relationship between adequacy of breast and axillary treatment, recurrence and survival was examined in 2122 women who had surgery with curative intent. A Cox proportional hazards model that included tumour size, node status, grade, socioeconomic status and use of adjuvant therapy was used. RESULTS: Inadequate treatment was associated with a significantly higher risk of local recurrence after breast-conserving surgery (relative hazard ratio (RHR) 4.19 (95 per cent confidence interval (c.i.) 2.73 to 6.43); P < 0.001). Inadequate axillary treatment was associated with a significantly higher risk of regional recurrence (RHR 2.29 (95 per cent c.i. 1.65 to 3.16); P < 0.001). The risk of death from breast cancer was significantly higher if locoregional treatment was inadequate (RHR 1.29 (95 per cent c.i. 1.07 to 1.55); P = 0.008). CONCLUSION: Adequate surgery is fundamental to the optimal treatment of breast cancer. Inadequate surgery resulted in higher recurrence rates despite adjuvant treatments.     

An in vitro model of hippocampal sharp waves: regional initiation and intracellular correlates

During slow wave sleep and consummatory behaviors, electroencephalographic recordings from the rodent hippocampus reveal large amplitude potentials called sharp waves. The sharp waves originate from the CA3 circuitry and their generation is correlated with coherent discharges of CA3 pyramidal neurons and dependent on activities mediated by AMPA glutamate receptors. To model sharp waves in a relatively large hippocampal circuitry in vitro, we developed thick (1 mm) mouse hippocampal slices by separating the dentate gyrus from the CA2/CA1 areas while keeping the functional dentate gyrus-CA3-CA1 connections. We found that large amplitude (0.3-3 mV) sharp wave-like field potentials occurred spontaneously in the thick slices without extra ionic or pharmacological manipulation and they resemble closely electroencephalographic sharp waves with respect to waveform, regional initiation, pharmacological manipulations, and intracellular correlates. Through measuring tissue O2, K+, and synaptic and single cell activities, we verified that the sharp wave-like potentials are not a consequence of anoxia, nonspecific elevation of extracellular K+ and dissection-related tissue damage. Our data suggest that a subtle but crucial increase in the CA3 glutamatergic activity effectively recruits a population of neurons thus responsible for the generation of the sharp wave-like spontaneous field potentials in isolated hippocampal circuitry.     

Deconditioning in the hospitalized elderly

Deconditioning is a complex process of physiological change following a period of inactivity, bedrest or sedentary lifestyle. It results in functional losses in such areas as mental status, degree of continence and ability to accomplish activities of daily living. It is frequently associated with hospitalization in the elderly. The most predictable effects of deconditioning are seen in the musculoskeletal system and include diminished muscle mass, decreases of muscle strength by two to five percent per day, muscle shortening, changes in periarticular and cartilaginous joint structure and marked loss of leg strength that seriously limit mobility. The decline in muscle mass and strength has been linked to falls, functional decline, increased frailty and immobility. The authors describe a three-pronged strategy to combat deconditioning that includes a model of care appropriate to the growing population of elderly clients, the creation of an "elder-friendly" hospital environment and an exercise program.