Response to Comment on "Atlantic and Pacific multidecadal oscillations and Northern Hemisphere temperatures".

Kravtsov et al. claim that we incorrectly assess the statistical independence of simulated samples of internal climate variability and that we underestimate uncertainty in our calculations of observed internal variability. Their analysis is fundamentally flawed, owing to the use of model ensembles with too few realizations and the fact that no one model can adequately represent the forced signal.

Habitat and behaviour of yellowfin tuna Thunnus albacares in the Gulf of Mexico determined using pop-up satellite archival tags.

This study presents the first data on movement, habitat use and behaviour for yellowfin tuna Thunnus albacares in the Atlantic Basin. Six individuals were tracked in the Gulf of Mexico using pop-up satellite archival tags. Records up to 80 days in length were obtained, providing information on depth and temperature preferences as well as horizontal movements. Thunnus albacares in the Gulf of Mexico showed a strong preference for the mixed layer and thermocline, consistent with findings for this species in other ocean basins. Fish showed a diel pattern in depth distribution, remaining in surface and mixed layer waters at night and diving to deeper waters during the day. The vertical extent of T. albacares habitat appeared to be temperature limited, with fish generally avoiding waters that were >6 degrees C cooler than surface waters. The vertical and thermal habitat usage of T. albacares differs from that of bigeye Thunnus obesus and bluefin Thunnus thynnus, Thunnus orientalis and Thunnus maccoyii tunas. These results are consistent with the results of earlier studies conducted on T. albacares in other oceans.

Characterization of a human plasma membrane heme transporter in intestinal and hepatocyte cell lines.

Heme is the most bioavailable form of dietary iron and a component of many cellular proteins. Controversy exists as to whether heme uptake occurs via specific transport mechanisms or passive diffusion. The aims of this study were to quantify cellular heme uptake with a fluorescent heme analog and to determine whether heme uptake is mediated by a heme transporter in intestinal and hepatic cell lines. A zinc-substituted porphyrin, zinc mesoporphyrin (ZnMP), was validated as a heme homolog in uptake studies of intestinal (Caco-2, I-407) and hepatic (HepG2) cell lines. Uptake experiments to determine time dependence, heme inhibition, concentration dependence, temperature dependence, and response to the heme synthesis inhibitor succinylacetone were performed. Fluorescence microscope images were used to quantify uptake and determine the cellular localization of ZnMP; ZnMP uptake was seen in intestinal and hepatic cell lines, with cytoplasmic uptake and nuclear sparing. Uptake was dose- and temperature dependent, inhibited by heme competition, and saturated over time. Preincubation with succinylacetone augmented uptake, with an increased initial uptake rate. These findings establish a new method for quantifying heme uptake in individual cells and provide strong evidence that this uptake is a regulated, carrier-mediated process.

Exposures of geotechnical laboratory workers to respirable crystalline silica.

Geotechnical laboratory testing involves the determination of the physical properties of soil, rock, and other building materials for engineering purposes. Individuals working in these laboratories are exposed to airborne soil, rock, and other dusts during the preparation and testing of these materials. Crystalline silica as quartz is a common constituent of these materials and represents a potential hazard to geotechnical laboratory workers when airborne as a respirable dust. The authors conducted an examination of the potential for geotechnical laboratory workers to be exposed to respirable dust and respirable quartz during the performance of three routine laboratory tasks. A task-based exposure assessment strategy was used. Although respirable dust was generated during the performance of each of these tasks, its impact on exposures was generally overridden by the presence of respirable quartz in the dust. Quartz content in the respirable dust ranged from below the detection limit to greater than 50 percent. Mean exposure to respirable quartz, based on the duration of the task and assuming no other exposures for the rest of the 8-hour day, exceeded the National Institute for Occupational Safety and Health (NIOSH) "action level" (the exposure level at which certain actions must be taken) of 0.025 mg/m3. If exposure was assumed to continue for the rest of the 8-hour day at the measured concentration, mean exposure to respirable quartz exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) time-weighted average (TWA), the Occupational Safety and Health Administration (OSHA) PEL, and the NIOSH REL. Seven percent of 57 individual task exposure measurements exceeded the TLV-TWA and the PEL, 18 percent exceeded the REL, and another 12 percent exceeded excursion limits as defined by ACGIH. The results of this study support the conclusion that geotechnical laboratory workers are potentially exposed to respirable crystalline silica as quartz at levels that may be harmful. Because the quartz content of the materials being tested in these laboratories is highly variable and is almost never determined prior to testing, all materials being tested in the geotechnical laboratory should be assumed to contain quartz. Appropriate controls should be used to protect workers from inhaling dusts generated from these materials.

Nurse practitioners in the county correctional facility setting: unique challenges and suggestions for effective health promotion.

The correctional facility practice setting is among the newer practice specialties emerging for nurse practitioners (NPs). As with any new setting, a variety of unique challenges continues to emerge. Because there is a relative paucity of literature regarding NP practice in this particular specialty, those practicing now do not have adequate resources to assist in the development of their practice. This article discusses some of the challenges unique to this area of practice and offers suggestions for incorporating theory-based health promotion interventions. This article is also an effort to begin development of a body of knowledge for NPs providing primary, secondary, and tertiary care to the inmate population of jails and prisons. Hopefully, nurse practitioners in this unique setting will be encouraged to share their own anecdotal and research-based suggestions for improving correctional facility practice.

Identifying barriers to the administration of HIV medications to county correctional facility inmates.

The purpose of this study was to investigate the process of HIV medication administration at a county correctional facility. Anecdotal data suggested serious barriers to the process. Professional and licensed practical nursing staff practicing at a New Jersey county correctional facility participated in focus group interviews designed to discuss the process of medication administration and potential barriers to that process. Analysis of data revealed five contextual themes: uniqueness of the county correctional facility setting, barriers perceived by nursing staff, inmates' perceptions of HIV infection, internal systems' barriers, and the role of systems external to the correctional facility.

Defining the acute in acute care nurse practitioner.

The role of the nurse practitioner in the tertiary care or hospital setting has become well established during the course of this decade. With the introduction of a national certifying examination for acute care nurse practitioners in 1995, it is important that the word acute be defined in a way that is acknowledged universally. Should an examination certifying acute care nurse practitioners contain critical care content? Are the terms acute care and critical care synonymous? The existing examination contains critical care content, but a review of relevant literature suggests a conflict. At times acute care and critical care are used interchangeably, and at other times they are discussed in a way that suggests they are two distinct specialties. This article presents the conflicting use of these two terms in the literature and provides a rationale for recognizing the differences. It is suggested that the definition of the word acute, as it is used in the title acute care nurse practitioner, be reexamined, and that either the content or the title of the certifying examination for acute care nurse practitioners be reconsidered.

Impact of a gerontological nurse practitioner on the nursing home elderly in the acute care setting.

A retrospective analysis of the length of stay of nursing home elderly patients admitted to the hospital demonstrates a significant decrease when patients are comanaged by a nurse practitioner and attending physicians. A comparison of the 20 most heavily populated diagnostic groups between 1993 and 1994 reveals a shorter average length of stay in 17 of the 20 diagnostic groups, and an overall mean decrease of 2.78 days for all groups. This article discusses the impact of the gerontological nurse practitioner on hospital length of stay of the nursing home elderly with acute illness. Research is needed to document advanced practices that decrease length of stay, as well as to control for extraneous variables.

The effects of octreotide on healing of small bowel anastomosis.

Octreotide (OCT) is a somatostatin analog used for its inhibitory action on multiple GI functions. Although octreotide has numerous clinical benefits, it has also been shown to inhibit postresectional hyperplasia of small bowel and hepatic regeneration. Because octreotide inhibits both trophic and anabolic hormones, we hypothesize that the use of octreotide may be detrimental in patients with a recent bowel anastomosis. To test this hypothesis, 60 male rats were randomized to four equal groups following small bowel anastomosis. Group I = control; Group II = 10 mg/day of hydrocortisone succinate; Group III = 2.5 micrograms/kg/day octreotide (equivalent of a clinical dose); Group IV = 25 micrograms/kg/day octreotide. Hydrocortisone was used as a negative control because it is known to have inhibitory effects on small bowel anastomotic healing. On postoperative Day 7, bursting pressures were measured. Serum T-kininogen levels, as a marker for systemic inflammation, and hydroxyproline content from the anastomotic segments were obtained. These results indicate that in the rat small bowel model, octreotide did not have any deleterious effect on anastomotic strength, systemic inflammation, and collagen content, even at high doses. Hydrocortisone, as expected, showed significant detrimental effects on bursting strength, as well as decreasing systemic inflammation. These findings have significant clinical implications, as octreotide could be used without jeopardizing the intestinal anastomosis.

Cardiac staircase and NMR-determined intracellular sodium in beating rat hearts.

Isolated, perfused rat hearts (30 degrees C, n = 13) were paced from 218 +/- 4 beats/min to 433 +/- 4 beats/min while systolic and diastolic pressure were recorded and intracellular Na+ concentration ([Na+]i) was monitored by 23Na nuclear magnetic resonance (NMR) spectroscopy. [Na+]i increased progressively with increasing stimulation frequency. In seven hearts (group I) an initial, progressive increase in systolic pressure was observed followed by a decrease in pressure with further increase in frequency. From the onset, a progressive decrease in systolic pressure was observed in group II (n = 6) in response to increased frequency. In group I an [Na+]i increase of up to 134 +/- 7% of control (P < 0.001) was observed, whereas in group II the gain in [Na+]i with increasing pacing rate was attenuated, reaching a maximum of 120 +/- 3% of control (P < 0.02). The differential pressure response between group I and group II hearts may reflect an enhanced sensitivity of rat hearts to the shortening of the restitution period of the sarcoplasmic reticulum, outweighing the positive inotropic effect induced by an increased [Na+]i. Only in rat hearts whose [Na+]i-induced increase in pressure outweights the restitution deficit would a complete positive inotropic effect be anticipated.

Effect of leukotriene inhibitor on cochlear blood flow in salicylate ototoxicity.

Our previous studies showed that salicylate ototoxicity is associated with decreased levels of vasodilating prostaglandins (PGs) and increased vasoconstricting leukotrienes (LTs) in the perilymph and reduced cochlear blood flow (CoBF). The purpose of this study was to test the hypothesis that leukotriene inhibitor prevents salicylate ototoxicity by preventing abnormal elevation of LT levels in the inner ear, thus averting a decrease in CoBF resulting from abnormal levels of arachidonic acid metabolites in the inner ear. Ototoxicity was induced in chinchillas by either local round window membrane (RWM) application or systemic treatment with salicylate both with and without pretreatment with leukotriene inhibitor (Sch 37224). A moderate reduction in CoBF was documented with both local RWM and systemic treatment with salicylate. Salicylate induced hearing loss and reduction in CoBF were prevented by pretreatment with a leukotriene inhibitor. This study suggests that leukotriene inhibitor prevents salicylate ototoxicity by averting a decrease in CoBF mediated by abnormal levels of arachidonic acid metabolites in the inner ear.

Effect of the radioprotector WR2721 on irradiation-induced injury to ciliated cells of eustachian tube.

Our previous studies revealed that injury to the ciliated cells of the eustachian tube may be the primary cause of irradiation-induced serous otitis media. The purpose of this study was to investigate the effects of the radioprotector WR2721 on irradiation-induced injury to ciliated cells of the eustachian tube (ET) in chinchillas. Twelve chinchillas were divided into two groups: the control group and the experimental group, which was pretreated with a single intraperitoneal dose of the radioprotector S-2-[3-aminopropylamino]ethylphosphorothioic acid (WR2721) 400 mg/kg. The two groups were exposed to 30 Gy of 13-MeV electrons in a single fraction to the area of the bullae and nasopharynx. Ciliary dysfunction was tested and ciliated cells of the ET were examined by scanning and transmission electron microscopy. Pretreatment with WR2721 was found to protect ciliated cells of the ET from irradiation injury.

Implementing TQM.

Total quality management (TQM) is an organized, systematic approach to problem solving and continuous improvement. American corporations have found that TQM is an excellent way to improve competitiveness, lower operating costs, and improve productivity. Increasing numbers of laboratories are investigating the benefits of TQM. For this month's column, we asked our respondents: What steps has your laboratory taken to implement TQM?