Mobilization of Bacillus thuringiensis plasmid pTX14-3.

The Bacillus thuringiensis subsp. israelensis (Bti) plasmid pTX14-3 has been reported to contain a gene, mob14-3, with considerable homology to genes encoding mobilization proteins from other gram-positive bacteria. We have used the aggregation-mediated conjugation system recently discovered in Bti to compare the mobilization kinetics of different derivatives of plasmid pTX14-3. Plasmid pTX14-3 has been found to replicate by the rolling-circle mechanism and to contain a locus suppressing the formation of high-molecular-weight DNA. We found that deleting a DNA fragment containing this locus increased the transfer frequency about twofold. The mobilization frequency of the plasmid containing the intact mob14-3 gene did not indicate a mobilization-enhancing activity of the encoded polypeptide. However, the presence of the mob14-3 gene seemed to increase the stability of the plasmid in exponential growth.

Respirators and respiratory care.

The intellectual and technological roots of respirators and respiratory care may be traced back hundreds of years. The clinical evolution has taken the better part of a century, and it has been most closely linked to the development of open-chest surgery. Resuscitation and the treatment of poliomyelitis also have contributed ideas and technology to this evolution. If its successful performance had depended only on respirators, open-chest surgery would have become clinical routine 50-80 years ago. In fact, many factors had to be under control, many modes of treatment had to be available, before the breakthrough in open-chest surgery could occur. The most important factor may have been the effective control of sepsis and hemorrhage. Open-chest surgery forced the change from single-agent deep anesthesia with spontaneous ventilation to a balanced technique, using multiple drugs or agents, with controlled ventilation. Open-chest surgery also necessitated that physicians specialize in anesthesiology. Scandinavian scientists and physicians have contributed greatly to the field of respirators and respiratory care, as has the specialty of anesthesiology.

Afterload reduction and preload augmentation improve the anesthetic management of patients with cardiac failure and valvular regurgitation.

Data were collected from 17 patients with valvular regurgitation and ventricular failure who were about to undergo prosthetic replacement of an insufficient cardiac valve. Awake control hemodynamic measurements revealed that these patients came to the operating room with a high systemic vascular resistance of 38 units and low cardiac and stroke volume indices of 2.2 L/min/m2 and 30 ml/beat/m2, respectively. A preanesthetic infusion of nitroprusside together with almost 2 L of lactated Ringer's solution caused vascular resistance to decrease to 19 units (normal) while filling pressure remained high. As a result, while the combined therapy continued, neither the induction of anesthesia nor surgical stimulation produced cardiovascular deterioration; in fact, cardiac index measured above 3.1 L/min/m2 and stroke volume index above 40 ml/beat/m2 throughout anesthesia and surgery. We conclude, therefore, that the combination of afterload reduction and preload augmentation provides the best possible environment within which to conduct the anesthetic management of patients with valvular regurgitation and ventricular failure.

Pheochromocytoma. Tumor localization and surgical management.

Recent experience with five cases of pheochromocytoma is the basis for this report. Pharmacological blockade is to be started with phenoxybenzamine before angiographic studies. Arteriography is the preferred localization technique, particularly when combined with bone-subtraction films. Anesthetic management requires special attention to premedication, close monitoring of cardiac rhythm, arterial and central venous pressure, and judicious administration of alpha and beta blockers. Methoxyflurane is no longer the anesthetic agent of choice because of possible nephrotoxicity. Multiple tumors are common. Wide surgical exposure with systematic palpation of autonomic ganglia must be carried out. Manipulation of the tumor does raise arterial blood pressure in spite of adequate preoperative blockade. The alpha blockade prevents the sudden and dangerous vascular collapse which used to be seen after removal of the tumor.