Quantifying the effectiveness of ultraviolet-C light at inactivating airborne Mycobacterium abscessus.

BACKGROUND: Mycobacterium abscessus (MABS) group are environmental organisms that can cause infection in people with cystic fibrosis (CF) and other suppurative lung diseases. There is potential for person-to-person airborne transmission of MABS among people with CF attending the same care centre. Ultraviolet light (band C, UV-C) is used for Mycobacterium tuberculosis control indoors; however, no studies have assessed UV-C for airborne MABS. AIM: To determine whether a range of UV-C doses increased the inactivation of airborne MABS, compared with no-UVC conditions. METHODS: MABS was generated by a vibrating mesh nebulizer located within a 400 L rotating drum sampler, and then exposed to an array of 265 nm UV-C light-emitting diodes (LED). A six-stage Andersen Cascade Impactor was used to collect aerosols. Standard microbiological protocols were used for enumerating MABS, and these quantified the effectiveness of UV-C doses (in triplicate). UV-C effectiveness was estimated using the difference between inactivation with and without UV-C. FINDINGS: Sixteen tests were performed, with UV-C doses ranging from 276 to 1104 µW s/cm2. Mean (±SD) UV-C effectiveness ranged from 47.1% (±13.4) to 83.6% (±3.3). UV-C led to significantly greater inactivation of MABS (all P-values ≤0.045) than natural decay at all doses assessed. Using an indoor model of the hospital environment, it was estimated that UV-C doses in the range studied here could be safely delivered in clinical settings where patients and staff are present. CONCLUSION: This study provides empirical in-vitro evidence that nebulized MABS are susceptible to UV-C inactivation.

Hierarchical tensile structures with ultralow mechanical dissipation.

Structural hierarchy is found in myriad biological systems and has improved man-made structures ranging from the Eiffel tower to optical cavities. In mechanical resonators whose rigidity is provided by static tension, structural hierarchy can reduce the dissipation of the fundamental mode to ultralow levels due to an unconventional form of soft clamping. Here, we apply hierarchical design to silicon nitride nanomechanical resonators and realize binary tree-shaped resonators with room temperature quality factors as high as 7.8 × 108 at 107 kHz frequency (1.1 × 109 at T = 6 K). The resonators' thermal-noise-limited force sensitivities reach 740 zN/Hz1/2 at room temperature and 90 zN/Hz1/2 at 6 K, surpassing state-of-the-art cantilevers currently used for force microscopy. Moreover, we demonstrate hierarchically structured, ultralow dissipation membranes suitable for interferometric position measurements in Fabry-Pérot cavities. Hierarchical nanomechanical resonators open new avenues in force sensing, signal transduction and quantum optomechanics, where low dissipation is paramount and operation with the fundamental mode is often advantageous.

Substance P initiates NFAT-dependent gene expression in spinal neurons.

Persistent hyperalgesia is associated with increased expression of proteins that contribute to enhanced excitability of spinal neurons, however, little is known about how expression of these proteins is regulated. We tested the hypothesis that Substance P stimulation of neurokinin receptors on spinal neurons activates the transcription factor nuclear factor of activated T cells isoform 4 (NFATc4). The occurrence of NFATc4 in spinal cord was demonstrated with RT-PCR and immunocytochemistry. Substance P activated NFAT-dependent gene transcription in primary cultures of neonatal rat spinal cord transiently transfected with a luciferase DNA reporter construct. The effect of Substance P was mediated by neuronal neurokinin-1 receptors that coupled to activation of protein kinase C, l-type voltage-dependent calcium channels, and calcineurin. Interestingly, Substance P had no effect on cyclic AMP response element (CRE)-dependent gene expression. Conversely, calcitonin gene-related peptide, which activated CRE-dependent gene expression, did not activate NFAT signaling. These data provide evidence that peptides released from primary afferent neurons regulate discrete patterns of gene expression in spinal neurons. Because the release of Substance P and calcitonin gene-related peptide from primary afferent neurons is increased following peripheral injury, these peptides may differentially regulate the expression of proteins that underlie persistent hyperalgesia.

Influence of photoperiod on N-acetyltransferase activity and melatonin in the fiddler crab Uca pugilator.

Melatonin and N-acetyltransferase (NAT) activity were measured in the eyestalks of fiddler crabs acclimated to various photoperiods: constant light, a L:D 12:12 h photoperiod, or constant dark. Following acclimation, eyestalks were collected every 3 h over a 24-h period; they were assayed for melatonin with a radioimmunoassay and for NAT activity with a radioenzymatic assay. In constant light, melatonin levels increased at 1300 h, from 142 to 431 pg x mg(-1) eyestalk; NAT activity increased concurrently, from 97 to 203 pmol x h(-1) x mg(-1) eyestalk, and both remained elevated until 0400 h. In the L:D 12:12 h photoperiod, melatonin levels increased at 1300 h from 28 to 230 pg x mg(-1) eyestalk, and though NAT activity increased significantly, from 80 to 122 pmol x h(-1) x mg(-1) eyestalk, an even greater increase occurred at 0400 h, when melatonin levels were low. In constant dark, melatonin levels increased at 1600 h, from 22 to 196 pg x mg(-1) eyestalk, with a concurrent increase in NAT activity from 93 to 140 pmol x mg(-1) x h(-1) eyestalk. However, the second peak in melatonin (111 pg x mg(-1)), occurring at 0400 h, was out of phase with the second peak of NAT activity (113 pmol x mg(-1) x h(-1) eyestalk) which occurred at 0700 h. NAT may be a rate-limiting step in melatonin synthesis in fiddler crabs under some conditions (constant light and the 1300 h peak in constant dark); however, NAT activity correlates poorly with melatonin levels in a L:D 12:12 h photoperiod and in constant dark relative to the 0400 h melatonin peak.

Epidural analgesia versus intravenous patient-controlled analgesia. Differences in the postoperative course of cancer patients.

BACKGROUND AND OBJECTIVES: This study evaluated 462 consecutive surgical cancer patients who underwent uncomplicated surgeries of the thorax or abdomen, or both, of more than 3 hours duration between 1989 and 1991. METHODS: Patients received either epidural analgesia (EA group) with 0.1% bupivacaine, 0.01% morphine sulfate after combined general-epidural anesthesia, or parenteral morphine therapy via intravenous patient-controlled analgesia (IV-PCA) after balanced general anesthesia after the operation. Patients in both the EA (n = 352) and IV-PCA (n = 100) groups were compared for demographics, length of surgical intensive care unit (SICU), and hospital stays. Moreover, the same comparisons were performed when patients were allocated into surgical subgroups: thoracic (TH), upper abdominal (UA), lower abdominal (LA), radical hysterectomies (RH), and RH with colon resection (RHCR). RESULTS: No differences existed with respect to age or sex between the EA and IV-PCA groups. All patients reported adequate dynamic pain control as evaluated with visual analog pain scores (VAS < 4/10), during the treatment periods (5 +/- 3 versus 5 +/- 2 days, EA versus IV-PCA). Overall, 262 (58%) patients were admitted to the SICU after the operation, 205 (58%) from the EA group and 57 (57%) from the IV-PCA group. Patients in the EA group required less ventilatory support than did those in the IV-PCA group (0.5 +/- 0.8 versus 1.2 +/- 0.9 days, P < .05). Patients in the EA group also spent less time in both the SICU (1.3 +/- 0.8 versus 2.8 +/- 0.6 days, P < .05) and in the hospital (11 +/- 3 versus 17 +/- 5 days, P < .05) than did their counterparts in the IV-PCA group. Significant differences were also found when subgroup comparisons were made. CONCLUSIONS: The use of both analgesic techniques was associated with satisfactory postoperative pain control. However, patients receiving epidural anesthesia and analgesia experienced faster recovery as judged by shorter mechanical ventilation time, and decreased SICU and hospital stays, resulting in significantly lower hospitalization costs. The use of perioperative epidural techniques should be considered to expedite recovery of surgical patients, and has the added benefit of being cost effective by reducing hospital stays.

Place of death in South Australia. Patterns from 1910 to 1987.

OBJECTIVES: To portray the changes in the place of death of South Australians during the 20th century and to examine the effects of sociodemographic and cause of death variables. DESIGN: Data relating to 2566 deaths from 1910 to 1987 were extracted from the records of funeral directors. A comparison of our sample of deaths with State mortality statistics, in terms of age, sex and diagnosis, was made to assure the representativeness of the sample. RESULTS: The proportion of deaths which occurred at home decreased from 55.6% in 1910 to 26.2% in 1970, and thereafter about a quarter of all deaths occurred at home. Most of the "institutionalisation of death" was due to increasing proportions of deaths in public hospitals; by 1970 over two-thirds of all deaths occurred in hospitals. After 1970 death has been transferred from hospitals to nursing homes and inpatient hospices. Multivariate analyses indicated that the institutionalisation trend was present after taking account of confounders (age, sex, marital status, occupation, number of children, and cause of death). CONCLUSIONS: Mortality patterns are determined by social and demographic characteristics of those who die, the availability of hospital and nursing home beds, changes to health insurance schemes, and the emergence of hospice care and related services. Further study is required to determine whether patterns of terminal care are cost-effective and medically appropriate.