Production and properties of a staphylococcin genetically controlled by the staphylococcal plasmid for exfoliative toxin synthesis.

Previous data from this laboratory showed that certain phage group 2 staphylococci contain a large 56S virulence plasmid containing genes that code for both exfoliative toxin (ET) and a specific staphylococcin. Optimal cultural conditions for bacteriocin production were similar to those found for ET production. The bacteriocin is an extracellular product produced in small quantities that can be neither extracted from cell pellets with 1 M NaCl nor induced with mitomycin C. The staphylococcin is active against a wide variety of gram-positive organisms and also against group 2 staphylococcal strains that have been cured of the plasmid carrying the staphylococcin marker. The bacteriocin is not inactivated by oxidation, mechanical agitation, or boiling for 15 min. It is sensitive to the action of trypsin and Pronase but not lysostaphin and is stable within a pH range of 4 to 9. It has an isoelectric point of approximately 7.7. Removal of the ampholytes and glycerol from electrofocused staphylococcin preparations resulted in total loss of bacteriocin activity.     

Acoustic-reflex dynamics and the loudness-discomfort level

Acoustic-reflex growth functions and Loudness-Discomfort Level (LDL) measures were obtained for 15 normal-hearing subjects. The hypothesis that signals considered uncomfortably loud occur at intensity levels that produce proportionately equal acoustic-reflex magnitudes was evaluated. Individual reflex growth functions were measured as a function of activator SPL for a 1000-Hz tone, a 4000-Hz tone, and a broadband noise. These growth functions were measured within subjects (two trials) and across subjects in terms of (a) percentage acoustic-impedance change at LDL, (b) percentage acoustic-reactance change at LDL, (c) acoustic impedance at LDL, (d) relative change in acoustic impedance at LDL, and (e) ratio of static acoustic impedance to change in acoustic impedance at LDL. Although the loudness and acoustic-reflex measures demonstrated good reliability across trials, the data showed large variability across subjects and did not support the experimental hypothesis. It was concluded, therefore, that the use of acoustic-reflex measures in the estimation of an individual's LDL is unwarranted.     

Five-year changes in middle ear function for older adults

Longitudinal changes in tympanometric measures of middle ear function over five years were reported for a large population of older adults. Findings were similar for men and women, for right and left ears, and across age groups from 48 to 92 years. Although some of the mean changes reached statistical significance, the vast majority of observed changes were small in magnitude relative to the observed variability and the tolerances of the measuring instrument. Observed mean changes in Peak Ytm for older adults were quite small and were in the positive direction. This is counter to changes that would be predicted on the basis of increases in the stiffness of the middle ear transmission system with advancing age suggested in earlier reports. Overall, the findings suggest little in the way of functional change in middle ear mechanics over a span of five years in older adults.     

Labor analgesia and cesarean delivery: an individual patient meta-analysis of nulliparous women

BACKGROUND: The authors performed an individual patient meta-analysis of 2,703 nulliparous women who were randomized to either epidural analgesia or intravenous opioids for pain relief during labor from five trials conducted at their hospital. The primary purpose in this meta-analysis was to evaluate the effects of epidural analgesia during labor on the rate of cesarean delivery. METHODS: Between November 1, 1993, and November 3, 2000, 2,703 nulliparous women (2,188 healthy parturients and 515 women with pregnancy-induced hypertension) in spontaneous labor at term were randomized to receive either epidural analgesia or intravenous opioid analgesia in the five studies. Epidural analgesia was initiated with either epidural bupivacaine or intrathecal sufentanil and was maintained with a low-dose (0.0625% or 0.125%) mixture of bupivacaine with fentanyl. Intravenous opioid analgesia was initiated with 50 mg meperidine and 25 mg promethazine hydrochloride and was maintained with intravenous boluses of meperidine as needed. RESULTS: A total of 1,339 nulliparous women were randomized to receive epidural analgesia, and 1,364 women were randomized to receive intravenous meperidine analgesia. There was no difference in the rate of cesarean deliveries between the two analgesia groups (epidural analgesia, 10.5% [140 of 1,339] vs. intravenous meperidine analgesia, 10.3% [141 of 1,364]; adjusted odds ratio, 1.04; 95% confidence interval, 0.81-1.34; P = 0.920). Significantly more women randomized to epidural analgesia had forceps deliveries compared to meperidine analgesia (13% [172 of 1,339] vs. 7% [101 of 1,364]; adjusted odds ratio, 1.86; 95% confidence interval, 1.43-2.40; P < 0.001). Epidural women had longer first and second stages of labor. Women who received epidural analgesia reported lower pain scores during labor and delivery compared to women who received intravenous meperidine analgesia. CONCLUSION: Epidural analgesia compared to intravenous meperidine analgesia during labor does not increase the number of cesarean deliveries.     

Evaluation of epicardial microwave ablation lesions: histology versus electrophysiology

Background

Pulmonary vein isolation is a hallmark in current surgical ablation for atrial fibrillation. However, validation of isolation remains cumbersome. We evaluated electrophysiologic and not histologic means to test isolation.

Methods

In 16 mongrel dogs, robot-assisted epicardial beating-heart microwave ablation (FLEX 10) was performed around the pulmonary veins. Electrophysiologic isolation was tested by pacing at 4 times threshold values inside and outside the pulmonary veins (exit and entrance block). The histology of lesions was studied for transmurality and continuity of the lesion lines. In 5 dogs, lesions were studied at various time intervals.

Results

Histologic evaluation of the lesions showed incomplete (48% ± 20%) circumferential myocardial damage in all dogs with acute lesions. Electrophysiologic evaluation showed completion of the box (entrance and exit block) in 8 dogs and in another 5 dogs after repeated ablation (p < 0.01 compared with histologic evaluation). Electrophysiologic evaluation of the dogs with chronic lesions showed completed lesions in 4 of 5 dogs directly after ablation. At follow-up (1 to 3 weeks), the isolations remained electrophysiologically complete. Histologic evaluation of the lesions 1 to 3 weeks after ablation showed complete (100%) circumferential lesions in all 4 dogs (p < 0.001 compared with the histology of dogs with acute lesions).

Conclusions

Directly after treatment, ablation lesions are best evaluated electrophysiologically, because complete (transmural and circumferential) lesions are not shown by histologic evaluation in the acute stage. After 1 to 3 weeks, the histology is in accordance with the electrophysiology. To obtain a complete isolation, online electrophysiologic evaluation during pulmonary vein microwave ablation is necessary to optimize the results.     

Mutational analysis of PINX1 in hereditary prostate cancer

BACKGROUND: Telomerase activity is increased in most tumors. PinX1 has recently been identified as a critical component in regulating telomerase activity. The PinX1 gene is located within chromosomal region 8p22-23, a region associated with LOH and potentially linked to increased prostate cancer risk. METHODS: PINX1 was re-sequenced in 159 hereditary prostate cancer (HPC) probands. Four non-synonymous coding variants were genotyped in 159 HPC families. RESULTS: Thirty-nine polymorphisms were identified in the HPC screening panel. Ten coding polymorphisms were identified, seven (Gln50His, Leu91Met, Gln206His, Arg215Ile, Thr220Ala, Ser254Cys, and Glu414Ala) of which were non-synonymous. The most common variants Thr220Ala and Ser254Cys were not significantly over-transmitted from affected parent to affected offspring. CONCLUSIONS: Based on these results, we conclude that PINX1 is not a major factor for HPC risk.     

Building Our Future: A Plea for Leadership

In recent years the spastic nature of the health care marketplace has continued to increase, which has greatly escalated the demands of leadership in academic medical centers. The expectations of leaders, including surgery chairs, have increased considerably, whereas their capacity for independent action has undeniably diminished. In such a predicament, it is useful to revisit fundamentals, using them as a guide to build a sound future. Five leadership principles are critical to building a better future: (1) recognizing that the work of leadership involves an inward journey of self-discovery and self-development; (2) establishing clarity around a set of core values that guide the organization as it pursues its goals; (3) communicating a clear sense of purpose and vision that inspires widespread commitment to a shared sense of destiny; (4) building a culture of excellence and accountability throughout the entire organization; and (5) creating a culture that emphasizes the development of leaders and leadership as an organizational capacity. Leadership and learning are inextricably linked. We must change the perception that learning in academic surgery is about correcting a deficit rather than a natural part of human growth and development. Our ability to learn, grow, and contribute to an organization is what provides each of us with meaning and identity. This feeling of being part of something special that is larger than ourselves is a powerful force and an important dividend of great leadership.