Acute Myocarditis After Black Widow Spider Bite: A Case Report.

The black widow spider (BWS) is a venomous spider whose bite can cause various clinical conditions that range from local damage to serious systemic complications, including death. Cases of myocarditis following a BWS bite are rare but they can be fatal on occasion. However, the prognostic significance of the bite and presentation of myocarditis is unknown. Our case involved a 50-year-old man who presented with myocarditis after being bitten by a BWS and subsequently admitted to the intensive care unit for cardiac monitoring. During the hospital stay, he showed worsening signs on both the electrocardiographic and echocardiographic evaluations despite therapeutic success. Subsequent cardiac magnetic resonance and coronary angiography investigations showed no significant alterations; blood and instrumental test results slowly improved, and the patient was discharged home after 12 days of hospitalization without complications. This case illustrates that acute myocarditis, although an infrequent complication of BWS bite, has the potential to be lethal. The correct diagnosis, which is not always easy to formulate, is important to identify those patients who can benefit from careful monitoring and specific therapies aimed at reducing the risk of life.

Mutual entrainment of bilaterally distributed circadian pacemaker.

The interactions between the bilaterally distributed components of the circadin system that controls the locomotor activity rhythm of the cockroach Leucophaea maderae were investigated in a series of surgical lesion experiments. Complete excision of one optic lobe (either right or left) or its surgical isolation from the central nervous system had no effect on the animals' ability to free-run in constant darkness nor was there any indication, as judged by postoperative pi values of any difference between left and right lobe pacemakers. However, these surgical procedures consistently resulted in a significant increase in tau over preoperative value while optic nerve section had no effect on tau. The propostion is developed that the left and right pacemakers in the two optic lobes are mutally coupled and that the compound pacemaker's period is shorter than either of its constituent pacemakers. It was also found that the integrity of either compound eye is sufficient to assure entrainment of both left and right pacemakers.

A test of the hypothesis that D2O affects circadian oscillations by diminishing the apparent temperature.

The period (tau) of a circadian pacemaker in the cockroach Leucophaea maderae is a nonmonotonic function of temperature. The slope of the curve (tau as a function of temperature) is negative at 20 degrees and positive at 30 degrees . When these insects are deuterated at 20 degrees and 30 degrees the period (tau) of the pacemaker lengthens in both cases, although there is a marked temperature dependence of D(2)O action. The increase in tau is nearly three times greater at 20 degrees than 30 degrees . This observation is a flat contradiction of a prediction made earlier that when D(2)O affects circadian pacemakers it does so by diminishing the apparent temperature of the cell. That prediction, however, involves an assumption that may well be unfounded. Unless D(2)O acts nonselectively on all the components in the system regulating tau, the prediction we sought to test is unfounded; and if D(2)O does not act nonselectively, the observed temperature dependence of D(2)O action is understandable in terms of simulating a lower temperature for those components it does affect.

General homeostasis of the frequency of circadian oscillations.

Some well-defined statistical regularities characterize the change in period (tau) of cockroach circadian oscillations subjected to a large temperature step. These are explainable in terms of the well-known temperature-compensation (homeostasis) of tau of circadian oscillations. The same regularities are detectable in published data on the effect of several other variables affecting several other circadian oscillations. The proposition is then developed that the temperature-compensation of tau is only a special case of a general homeostatic conservation of the frequency of circadian oscillations in the face of all changes they are likely to encounter in the cell. Such a general homeostasis of tau is a functional prerequisite for an oscillator to function as a useful "clock."

A differential effect of heavy water on temperature-dependent and temperature-compensated aspects of circadian system of Drosophila pseudoobscura.

D(2)O is the only "chemical" agent that consistently affects the frequency of circadian oscillations: its effect is now known to be so widespread and predictable that its action merits closer study as a potential clue to the currently obscure concrete nature of circadian oscillators. The great diversity of D(2)O effects on biological systems in general is briefly reviewed and the need for rejectable hypotheses concerning the action of D(2)O on circadian clocks is stressed because current speculation on its action yields "predictions" expected from almost any hypothesis. We consider the hypothesis that it "diminishes the apparent temperature" of the cell and proceed to test this by examining the effect of D(2)O on temperature-dependent and temperature-compensated aspects of the circadian system in Drosophila. We find these components respond as differentially to D(2)O as they do to temperature; we conclude, however, with a warning that this result may be equivocal if, as we now suspect, the frequency of circadian oscillations is generally homeostatically conserved-not only in the face of temperature change, but change in any variable to which it is sensitive. More crucial tests of the temperature-equivalence hypothesis for D(2)O action are defined.