Bi-Arrhenius Diffusion and Surface Trapping of

We report measurements of the diffusion rate of isolated ion-implanted ^{8}Li^{+} within ∼120 nm of the surface of oriented single-crystal rutile TiO_{2} using a radiotracer technique. The α particles from the ^{8}Li decay provide a sensitive monitor of the distance from the surface and how the depth profile of ^{8}Li evolves with time. The main findings are that the implanted Li^{+} diffuses and traps at the (001) surface. The T dependence of the diffusivity is described by a bi-Arrhenius expression with activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures it has a much smaller barrier of 0.0313(15) eV. We consider possible origins for the surface trapping, as well the nature of the low-T barrier.

Treatment of Refractory Gastrointestinal Bleeding in Patients With Portal Hypertension: A Case Series and Treatment Algorithm.

In patients with portal hypertension, ectopic varices can develop at any site along the gastrointestinal tract outside the classically described gastroesophageal location. Like esophageal variceal hemorrhage, bleeding from ectopic varices can be life-threatening. Diagnosis and treatment of ectopic varices can be challenging; to date, no effective treatment algorithm has been described. A systematic teamwork approach to diagnosing and treatment of ectopic varices is required to successfully manage hemorrhage from ectopic varices.

Awareness of Medical Fitness to Drive Guidelines among Occupational Physicians and Psychiatrists.

Irrespective of national guidelines for medical fitness to drive, this study investigated the cumulative expert wisdom of clinicians regarding minimum periods of driving cessation required for patients suffering from conditions that can impair driver capability. Occupational Physicians (196) and Psychiatrists (103) completed an online questionnaire. For private motorists, the modal response for anxiety and depression favoured clinical discretion, followed by three month cessations for hypomania, acute psychosis, schizophrenia and alcohol dependence and six weeks for alcohol misuse/dependence. For professional drivers the modal value for anxiety and depression was three months, rising to six months for hypomania, psychosis and schizophrenia and 12 months for both alcohol misuse/dependence. Chi-square test results indicated statistically significant differences in clinical opinion between Occupational Physicians and Psychiatrists regarding driving cessation times for drivers suffering from psychiatric and alcohol misuse conditions except for alcohol dependence. Further studies are warranted to investigate these issues in more depth.

Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity.

Chemisorption of muonium onto the surface of gold nanoparticles has been observed. Muonium (µ+e-), a light hydrogen-like atom, reacts chemically with uncapped 7 nm gold nanoparticles embedded in mesoporous silica (SBA-15) with a strong temperature-dependent rate. The addition rate is fast enough to allow coherent spin transfer into a diamagnetic muon state on the nanoparticle surface. The muon is well established as a sensitive probe of static or slowly fluctuating magnetic fields in bulk matter. These results represent the first muon spin rotation signal on a nanoparticle surface or any metallic surface. Only weak magnetic effects are seen on the surface of these Au nanoparticles consistent with Pauli paramagnetism.

ß-NMR Investigation of the Depth-Dependent Magnetic Properties of an Antiferromagnetic Surface.

By measuring the prototypical antiferromagnet α-Fe_{2}O_{3}, we show that it is possible to determine the static spin orientation and dynamic spin correlations within nanometers from an antiferromagnetic surface using the nuclear spin polarization of implanted ^{8}Li^{+} ions detected with ß-NMR. Remarkably, the first-order Morin spin reorientation in single crystal α-Fe_{2}O_{3} occurs at the same temperature at all depths between 1 and 100 nm from the (110) surface; however, the implanted nuclear spin experiences an increased 1/T_{1} relaxation rate at shallow depths revealing soft-surface magnons. The surface-localized dynamics decay towards the bulk with a characteristic length of ε=11±1 nm, closely matching the finite-size thresholds of hematite nanostructures.

Probing Atmospheric Electric Fields in Thunderstorms through Radio Emission from Cosmic-Ray-Induced Air Showers.

We present measurements of radio emission from cosmic ray air showers that took place during thunderstorms. The intensity and polarization patterns of these air showers are radically different from those measured during fair-weather conditions. With the use of a simple two-layer model for the atmospheric electric field, these patterns can be well reproduced by state-of-the-art simulation codes. This in turn provides a novel way to study atmospheric electric fields.

Dynamic social support networks of younger black men who have sex with men with new HIV infection.

Rising rates of HIV infection among younger black men who have sex with men (YBMSM) in the USA have generated a public health emergency. Living with HIV requires deep and persistent social support often available only from close confidants. Enlisting endogenous support network members into the care of HIV-infected YBMSM may help shape sustainable supportive environments, leading to long-term improvements in mental and HIV-specific health outcomes. The present study examined trends in support network change over time after new HIV diagnoses among 14 YBMSM. Participants completed a social network survey that utilized sociograms to record support confidants (SCs) preceding HIV diagnosis and at one and nine months postdiagnosis. Reported SCs included family of origin, friends, sex partners, and other associates. Analysis revealed three distinct patterns of change: high gain, high turnover, and stable networks. These patterns offer valuable insights into the social support of YBMSM during the period following diagnosis. This research underscores a growing movement to embrace key support figures in the lives of YBMSM, who may be critical to promoting overall health and adherence to HIV-care.

High vitamin D3 diet administered during active colitis negatively affects bone metabolism in an adoptive T cell transfer model.

Decreased bone mineral density (BMD) represents an extraintestinal complication of inflammatory bowel disease (IBD). Vitamin D3 has been considered a viable adjunctive therapy in IBD. However, vitamin D3 plays a pleiotropic role in bone modeling and regulates the bone formation-resorption balance, depending on the physiological environment, and supplementation during active IBD may have unintended consequences. We evaluated the effects of vitamin D3 supplementation during the active phase of disease on colonic inflammation, BMD, and bone metabolism in an adoptive IL-10-/- CD4⁺ T cell transfer model of chronic colitis. High-dose vitamin D3 supplementation for 12 days during established disease had negligible effects on mucosal inflammation. Plasma vitamin D3 metabolites correlated with diet, but not disease, status. Colitis significantly reduced BMD. High-dose vitamin D3 supplementation did not affect cortical bone but led to a further deterioration of trabecular bone morphology. In mice fed a high vitamin D3 diet, colitis more severely impacted bone formation markers (osteocalcin and bone alkaline phosphatase) and increased bone resorption markers, ratio of receptor activator of NF-κB ligand to osteoprotegrin transcript, plasma osteoprotegrin level, and the osteoclast activation marker tartrate-resistant acid phosphatase (ACp5). Bone vitamin D receptor expression was increased in mice with chronic colitis, especially in the high vitamin D3 group. Our data suggest that vitamin D3, at a dose that does not improve inflammation, has no beneficial effects on bone metabolism and density during active colitis or may adversely affect BMD and bone turnover. These observations should be taken into consideration in the planning of further clinical studies with high-dose vitamin D3 supplementation in patients with active IBD.

Effect of transjugular intrahepatic portosystemic shunt on thrombocytopenia associated with cirrhosis.

Thrombocytopenia is a frequent complication of cirrhosis. Its pathogenesis is not well known, but it has been suggested that splenic congestion induced by portal hypertension may be a major contributory factor. However, the available data regarding the effect of portal decompression either by surgical shunts or transjugular intrahepatic portosystemic shunt (TIPS) on peripheral platelet count in cirrhotics is conflicting. We studied the effects of TIPS on platelet count and mean platelet volume, following a successful TIPS placement. The platelet count had a tendency to decrease but was not statistically significant (120,100 +/- 72,100/mm3 before TIPS vs 99,800 +/- 51,400/mm3 after TIPS). The mean platelet volume remained essentially unchanged (9.8 +/- 1.5 fL before TIPS and 9.9 +/- 1.5 fL after TIPS). These results confirm that TIPS has an unpredictable effect on platelet count in cirrhotic patients with thrombocytopenia. The lack of a consistent increase in the peripheral mean platelet volume following TIPS placement suggests that TIPS is unable to significantly enhance the release of platelets sequestered in the splenic compartment in portal hypertension.

Radiation exposure to personnel during examination of limbs of horses with a portable hand-held fluoroscopic unit.

OBJECTIVES: To determine radiation exposure to personnel during fluoroscopic imaging of limbs of horses with a portable unit and to determine distance from the c-arm at which radioprotective clothing is not required. DESIGN: Repeated-measures cohort study. SAMPLE POPULATION: Part 1, 1 forelimb and 1 hind limb from each of 5 equine cadavers; parts 2 and 3, personnel involved during imaging of limbs of 5 and 9 horses, respectively. PROCEDURE: Radiation exposure rates were mapped around the suspended c-arm of a portable fluoroscopy unit during imaging of various joints of equine cadaver limbs. During similar examinations in live horses, exposure rates to the fluoroscopist and assistant were measured. Mean duration for fluoroscopy of various joints was determined by observing an experienced fluoroscopist. Exposure to fluoroscopists and assistants per examination and per annum was estimated. RESULTS: Radiation exposure rates were dependent on distance and direction relative to the c-arm and consistently highest on the tube side of the unit. Exposure was significantly greater than background amounts until approximately 4.7 m from the c-arm. During examination of live horses, exposure was highest to the fluoroscopist's hand nearest the tube. Typically, exposure to the fluoroscopist and assistant during carpal examination was 25 to 40 times greater than that for comparable radiographic examination. Annual exposure for fluoroscopists was more than twice the recommended maximum permissible dose. CONCLUSIONS AND CLINICAL RELEVANCE: Fluoroscopic imaging of limbs of horses represents a major source of radiation exposure. Annual maximum permissible doses of radiation will be rapidly exceeded if required radioprotective clothing is not worn.

Surfactant associated protein-A inhibits human lymphocyte proliferation and IL-2 production.

The hyporesponsive state of lung-derived mononuclear leukocytes has been, in part, attributed to the effects of the lipid rather than the protein components of pulmonary surfactant. In the present study, however, the results suggest that purified preparations of pulmonary surfactant-associated protein A (SP-A) suppress both phytohemagglutinin (PHA, 1 microgram/ml)- and anti-CD-3 (1 to 10 ng/ml) activated proliferation of human peripheral blood and tonsillar mononuclear cells in a dose-dependent manner at concentrations as low as 50 pM (6.25 micrograms/ml) when added at the initiation of cultures. Addition of SP-A to PHA-stimulated peripheral blood mononuclear cells (PBMC) as late as 24 to 36 h after PHA was also capable of suppressing [3H]thymidine incorporation measured at 72 h. In contrast, concanavalin A (Con A; 2 micrograms/ml)-stimulated PBMC proliferation was slightly augmented by the addition of SP-A. Analysis of the supernatants of PHA-stimulated cultures treated with SP-A revealed that accompanying the inhibition of proliferation was a corresponding decline in measurable interleukin-2 (IL-2) concentrations, from 154 pg/ml for the PHA-treated cells to 57.8, 28.4, 5.2, and less than 2 pg/ml of IL-2 when SP-A was added at 6.25, 12.5, 25, and 50 micrograms/ml, respectively. We suggest that the action of SP-A on PHA-stimulated human PBMC may involve the blocking of a costimulatory signal crucial for in vitro T-cell activation.

Side effects associated with influenza vaccination in healthy working adults. A randomized, placebo-controlled trial.

BACKGROUND: Concern about side effects is a barrier to influenza vaccination. This randomized, double-blind, placebo-controlled trial assessed side effects following vaccination among healthy working adults. METHODS: Healthy working adults were recruited during October and November 1994 and were randomized to receive influenza vaccine or placebo injections. Local and systemic symptoms during the week following the injection were evaluated through structured telephone interviews. RESULTS: Of 849 subjects enrolled in the study, 425 received a placebo and 424 received influenza vaccine. Baseline characteristics were similar between the groups, and 99% of subjects completed interviews to assess side effects after the study injection. No differences were seen between the 2 groups for the systemic symptoms of fever, myalgias, fatigue, malaise, or headaches. Overall, 35.2% of placebo and 34.1% of vaccine recipients reported at least 1 of these systemic symptoms (P = .78, chi 2). Vaccine recipients reported a higher rate of arm soreness at the injection site than did placebo recipients (63.8% vs 24.1%, P < .001). Local reactions were mild in both groups and infrequently resulted in decreased use of the arm. After logistic regression, female sex (odds ratio [OR], 1.5;95% confidence interval [CI], 1.1-2.1), age younger than 40 years (OR, 1.6;95% CI, 1.2-2.2), and coincidental upper respiratory tract illness (OR, 4.6; 95% CI, 3.2-6.6) were independently associated with higher rates of systemic symptoms. In the multivariate model, vaccine again was not associated with systemic symptoms (OR, 0.9; 95% CI, 0.7-1.2). CONCLUSIONS: Influenza vaccination of healthy working adults is not associated with higher rates of systemic symptoms when compared with placebo injection. These findings should be useful to physicians and other health care providers as they counsel patients to take advantage of an important opportunity for disease prevention and health protection.

The effectiveness of vaccination against influenza in healthy, working adults.

BACKGROUND: Although influenza causes substantial morbidity and mortality in all age groups, current recommendations emphasize annual immunization for people at high risk for complications of influenza. We conducted a double-blind, placebo-controlled trial of vaccination against influenza in healthy, working adults. METHODS: In the fall of 1994, we recruited working adults from 18 to 64 years of age from in and around the Minneapolis-St. Paul area and randomly assigned them to receive either influenza vaccine or placebo injections. The primary study outcomes included upper respiratory illnesses, absenteeism from work because of upper respiratory illnesses, and visits to physicians' offices for upper respiratory illnesses. The economic benefits of vaccination were analyzed by estimating the direct and indirect costs associated with immunization and with upper respiratory illnesses. RESULTS: We enrolled a total of 849 subjects. Baseline characteristics were similar in the two groups. During the follow-up period, consisting of the 1994-1995 influenza season (December 1, 1994, through March 31, 1995), those who received the vaccine reported 25 percent fewer episodes of upper respiratory illness than those who received the placebo (105 vs. 140 episodes per 100 subjects, P < 0.001), 43 percent fewer days of sick leave from work due to upper respiratory illness (70 vs. 122 days per 100 subjects, P = 0.001), and 44 percent fewer visits to physicians' offices for upper respiratory illnesses (31 vs. 55 visits per 100 subjects, P = 0.004). The cost savings were estimated to be $46.85 per person vaccinated. CONCLUSIONS: Vaccination against influenza has substantial health-related and economic benefits for healthy, working adults.

Multiparameter flow cytometric DNA analysis of effusions: a prospective study of 36 cases compared with routine cytology and immunohistochemistry.

Single-parameter flow cytometry (SFCM) is limited in its ability to detect aneuploid and diploid malignant cells or accurately estimate S-phase fractions (SPF) in effusions because of the high degree of contamination by benign mesothelial cells and inflammatory cells. We examined 36 pleural and peritoneal fluids by conventional cytology and multiparameter FCM (MFCM) to analyze the DNA content of cells expressing epithelial markers cytokeratin, epithelial membrane antigen, carcinoembryonic antigen, BRST-1, or BRST-3 (B72.3) and compared the results to those found with SCFM. The cases were also studied by immunohistochemistry using the same antibody panel. By routine cytology, 14 of the 36 cases were classified as carcinomas, 11 as reactive, 1 as mesothelioma, and 10 as suspicious. MFCM allowed reclassification of 5 of the 10 suspicious cases as carcinomas and the remaining 5 as reactive cases based on ploidy and marker expression. Whereas SFCM detected only 13 nondiploid carcinomas, MFCM detected 4 diploid and 15 nondiploid carcinomas. All reactive cases were diploid by SFCM or MFCM. The mesothelioma case showed were distinct peaks by MFCM, a diploid peak with SPF of 13.4% and a tetraploid peak with SPF of 36.1%. The SPF of the nondiploid carcinomas ranged from 5.9 to 50.4% and diploid carcinomas, from 3.5 to 14.5% when gated on epithelial cells. The reactive cases had SPF ranging from 0.4 to 4.4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitriol and its synthetic analogue MC 903 inhibit the interleukin-2-induced migration of human lymphocytes.

Sarcoidosis is characterized by the accumulation of activated lymphocytes in the lungs and other organs and by the spontaneous production of the active form of vitamin D, calcitriol. We hypothesized that calcitriol may modulate the responsiveness of human lymphocytes to the relevant biologic mediator, interleukin-2 (IL-2). After culture for 48 h with phytohemagglutinin, human peripheral blood lymphocytes migrated through nitrocellulose filters, secured in microchemotaxis chambers, in response to IL-2. When calcitriol at 1 nM was included in the cultures, the migratory response to IL-2 was completely abrogated. This inhibitory effect was seen despite the fact that cultured lymphocytes continued to express the IL-2 receptor and other activation markers. A similar but more rapid effect could be demonstrated by including calcitriol in the lower well during our 3-h chemokinesis assay. Calcitriol blocked IL-2-induced lymphocyte migration in a dose-dependent fashion. The synthetic noncalcemic vitamin D analogue MC 903 was equally effective in this assay. IL-2-induced migration could also be prevented by the protein kinase C inhibitor H-7, but calcitriol appeared to be at least 1,000 times more potent. Our studies suggest that calcitriol is a potent natural immunomodulator with rapid suppressive effects that may be mediated through protein kinase C. Synthetic analogues such as MC 903 may offer exciting therapeutic opportunities.

Effect of platelet activating factor (PAF) on the migration of human lymphocytes.

BACKGROUND: There is growing evidence to suggest the importance of the lymphocyte in the pathogenesis of asthma, particularly in the late phase reactions and ongoing bronchial hyperreactivity. Platelet activating factor (PAF) has also been identified as a potentially important mediator in asthma. METHODS: The migration of human peripheral blood lymphocytes obtained from normal volunteers in response to PAF and the effect of PAF antagonists was studied in a well standardised in vitro assay using nitrocellulose micropore filters in a microchemotaxis chamber. RESULTS: PAF is a potent stimulus to in vitro human lymphocyte migration; at an optimal concentration of 1 nM it augmented lymphocyte chemokinesis to 310% (SE 33%) of control values. The response to PAF appears to be specific since lyso-PAF and other related membrane phospholipids had no effect. PAF-induced migration could be abrogated by specific PAF receptor antagonists such as WEB 2086 (100 nM), and was partially blocked by the cyclooxygenase inhibitor flurbiprofen at a concentration of 1 microM. CONCLUSIONS: PAF stimulates the in vitro migration of human lymphocytes through a specific PAF receptor. Part of the response may be due to the generation of cyclooxygenase products. PAF may play a part in the recruitment of lymphocytes to asthmatic airways.

Necrotizing sarcoid granulomatosis with pleural involvement. Clinical and radiographic features.

The clinical, functional, radiologic, and pathologic characteristics of seven cases of necrotizing sarcoid granulomatosis (NSG) are presented. The population consisted of five women and two men, with an average age of 36 years. Each patient's predominant presenting complaint was pleuritic chest pain. Pulmonary function testing demonstrated a variety of abnormal patterns. Computed tomography (CT) of the chest showed solitary or multiple nodules in all patients, occasionally associated with pulmonary infiltrates in the lower lobes. Pleural involvement was seen on CT scanning in six patients and mediastinal adenopathy was present in five. Biopsy specimens of the lung lesions revealed confluent epithelioid granulomata associated with necrosis and vasculitis. Pleural involvement by confluent granulomata was a prominent feature in four patients. Follow-up has ranged from 6 months to 4 years. All patients are now asymptomatic, the majority having received prednisone. One patient received methotrexate as a steroid-sparing measure. We conclude that NSG is distinguishable from sarcoidosis as a clinicopathologic entity in which pleural involvement is a frequent finding. Treatment with steroids appears to hasten recovery.

Parental and medical over-administration of acetaminophen causing lethal hepatotoxicity in a 10-year-old.

A 10-year-old girl with acute influenza B virus disease was given repetitive doses of acetaminophen by her mother to reduce the child's fever. When finally seen by trained medical personnel, the child was experiencing abdominal pain, nausea, and vomiting, which are classic signs of acetaminophen hepatotoxicity. Despite these findings, the child was given additional acetaminophen and experienced lethal hepatotoxicity.