Estimating meiotic gene conversion rates from population genetic data

Gene conversion plays an important part in shaping genetic diversity in populations, yet estimating the rate at which it occurs is difficult because of the short lengths of DNA involved. We have developed a new statistical approach to estimating gene conversion rates from genetic variation, by extending an existing model for haplotype data in the presence of crossover events. We show, by simulation, that when the rate of gene conversion events is at least comparable to the rate of crossover events, the method provides a powerful approach to the detection of gene conversion and estimation of its rate. Application of the method to data from the telomeric X chromosome of Drosophila melanogaster, in which crossover activity is suppressed, indicates that gene conversion occurs approximately 400 times more often than crossover events. We also extend the method to estimating variable crossover and gene conversion rates and estimate the rate of gene conversion to be approximately 1.5 times higher than the crossover rate in a region of human chromosome 1 with known recombination hotspots.

A phagocytosis mutant of Entamoeba histolytica is less virulent due to deficient proteinase expression and release

Cysteine proteinases are key virulence factors of Entamoeba histolytica that are released during the process of invasion. We used a chemical mutant of E. histolytica strain HM-1:IMSS, clone L6, which is deficient in virulence, phagocytosis, and cysteine proteinase activity to help define the mechanisms of cysteine proteinase release. All cysteine proteinase genes of wild type HM-1 were present in the L6 mutant genome, but three of the major expressed proteinases, ehcp1, ehcp2, and ehcp5 were both transcribed, translated, and released at lower levels in L6. We hypothesized that a central protein such as the calcium binding protein 1, EhCaBP1, which is required for both phagocytosis and exocytosis might be deficient in this mutant. We found that both mRNA and proteinase levels of EhCaBP1 were decreased in L6. These findings provide an important link between phagocytosis, passive release of multiple cysteine proteinases, and attenuated virulence of this E. histolytica mutant.

The distribution and causes of meiotic recombination in the human genome

Using the statistical analysis of genetic variation, we have developed a high-resolution genetic map of recombination hotspots and recombination rate variation across the human genome. This map, which has a resolution several orders of magnitude greater than previous studies, identifies over 25,000 recombination hotspots and gives new insights into the distribution and determination of recombination. Wavelet-based analysis demonstrates scale-specific influences of base composition, coding context and DNA repeats on recombination rates, though, in contrast with other species, no association with DNase I hypersensitivity. We have also identified specific DNA motifs that are strongly associated with recombination hotspots and whose activity is influenced by local context. Comparative analysis of recombination rates in humans and chimpanzees demonstrates very high rates of evolution of the fine-scale structure of the recombination landscape. In the light of these observations, we suggest possible resolutions of the hotspot paradox.

Proinflammatory cytokine levels in saliva before and after treatment of (erosive) oral lichen planus with dexamethasone

OBJECTIVE

To explore the potential of detecting the level of proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1-alpha (IL-1-alpha), IL-6, and IL-8 in whole unstimulated saliva (WUS) in monitoring the therapeutic effects of topical dexamethasone on these salivary cytokines in subjects with erosive oral lichen planus (OLP).

STUDY DESIGN

Thirteen definitively diagnosed OLP subjects were enrolled in the study as were 13 age- and sex-matched controls. The OLP subjects were treated with 0.1% dexamethasone oral rinse for 6 weeks. Prior to treatment and at the end of clinical trial, the visual analog scale (VAS) for symptoms was recorded, WUS was collected and these proinflammatory cytokines were analyzed by ELISA.

RESULTS

Following the dexamethasone treatment, the levels of TNF-alpha, IL-1-alpha, IL-6, and IL-8 were decreased significantly, and IL-1-alpha and IL-8 were detected at a level without a statistically significant difference from controls. VAS value was decreased significantly and was found to significantly correlate with the decrease in IL-1-alpha and IL-8 levels.

CONCLUSIONS

These preliminary results indicate that salivary analysis of NF-kappaB-dependent cytokines may be applied to monitoring the therapeutic response of OLP.

Effect of backpack fit on lung function

Carrying loads close to the trunk with a backpack causes a restrictive type of change in lung function in which Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 s (FEV1) are reduced without a corresponding decrement in the FEV1.FVC( - 1) %. It is not known whether this is due to the weight of the load acting on the chest or to the tightness of fit of the shoulder and chest straps and waist belt of the pack harness. This study examined FVC, FEV1, FEV1.FVC( - 1) %, peak expiratory flow (PEF), forced expiratory flow between 0.2 and 1.2 s (FEF0.2 - 1.2) after the start of expiration and between 25 and 75% of each FVC (FEF25 - 75%) in 12 healthy males wearing a 15 kg backpack in which the shoulder and chest straps and hip belt were loosened by 3 cm from a 'comfort fit' to achieve a 'loose pack' fit (LPF) and tightened by 3 cm from CF to achieve a 'tight pack' fit (TPF). In comparison with the control condition of no pack, a loose pack fit significantly reduced FVC (by 3.6%, p < 0.01), FEV1 (by 4.3%, p < 0.01) and FEF25 - 75% (by 8.4%, p < 0.01). A tight pack fit significantly reduced FVC (by 8.1%, p < 0.01) and FEV1 (by 9.1%, p < 0.001). It also significantly reduced FEF0.2 - 1.2 (by 7.3%, p < 0.05) and FEF25 - 75% (by 21%, p < 0.01). In comparison with a loose pack fit, the tight pack fit was associated with a significantly lower FVC (by 4.6%, p < 0.01), FEV1 (by 5.0%, p < 0.01), FEF25 - 75% (by 13.8%, p < 0.01) and a fall in FEF0.2 - 1.2 (by 5.5%). The latter was approaching significance (p = 0.077). There were no significant changes in FEV1.FVC( - 1)% and PEF. It is concluded that tightening the fit of a backpack significantly affects lung function in a manner that is typical of a restrictive change in lung function and is very similar in pattern to that of wearing a loosely fitted loaded backpack. The effect of tightness of fit is additional to that due to the weight of the load alone and may also reduce expiratory flow at low lung volumes.

Problems with capnography at high altitude

The aim of this study was to investigate why capnographs malfunction at high altitude, in order to suggest ways of improving instrument reliability. Four machines were decompressed to simulated high altitude and measurements taken. The study showed that the reduced air density at altitude has effects upon the pump, causing difficulty in entraining gas, and that high altitude has additional effects upon calibration of the instruments.

High average power, all-solid-state external resonator Raman laser

As much as 3 W of average power at 1064 nm from a diode-pumped Nd:YAG laser, Q switched at 4 kHz, was used to pump an external-resonator, crystalline Ba(NO3)2 Raman laser generating a maximum of 1.3-W output at the first Stokes wavelength of 1197 nm. The slope efficiency was 63% with respect to the fundamental power incident on the Ba(NO3)2 crystal. A reduction in the beam quality of the Stokes output from M2 approximately 1.4 at lower Stokes powers to M2 approximately 3.4 at higher powers is attributed to thermal loading of the Raman-active crystal.

Repetition of an unusual stress fracture in an anorexic man: a case report

Stress fractures of the fibula commonly occur distally in runners, whereas stress fractures of the proximal fibula are uncommon and typically occur in jumpers. Furthermore, it is rare for a stress fracture to be repeated in the same bone. We report a case of a repeated stress fracture of the proximal fibula in a male runner with abnormal gait that primarily involved excessive pronation. Unusual risk factors in this case were anorexia nervosa and use of an inhaled corticosteroid. The patient was treated conservatively, and healing of the fracture was completed at 12 weeks.

Case-control study of intracranial tumors among employees at a petrochemical research facility

This case-control study evaluated the relation between potential exposure to chemical and physical agents and the occurrence of intracranial tumors among employees at a petrochemical research facility. Cases were employees with glioma (n = 6) or benign intracranial tumors (n = 6). Controls (n = 119) were individually matched to cases on gender and birth year, and they were alive and did not have an intracranial tumor at the case's diagnosis date. Exposure information came from interviews with subjects or surrogates and from corporate records on agents used in research projects. Analyses computed matched odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for self-reported exposure to 15 agents and project-based estimates of exposure to 29 agents. For gliomas, the OR was elevated for self-reported exposure to ionizing radiation (OR, 15.7; CI, 1.4 to 179.4), n-hexane (OR, infinity; CI, 1.4 to infinity), organometallics (OR, 9.4; CI, 1.5 to 59.7), and amines other than nitrosamines (OR, 6.0; CI, 1.0 to 35.7). The OR also was elevated for project-based potential use of ionizing radiation (OR, 9.6; CI, 1.7 to 55.2) and for potential use of n-hexane lasting at least 4 years (OR, 16.2; CI, 1.1 to 227.6). For benign intracranial tumors, the OR was elevated only for self-reported exposure to ionizing radiation (OR, 5.4; CI, 1.7 to 43.1) and other amines (OR, 5.2; CI, 0.9 to 29.5). Occupational exposure may have contributed to the glioma excess, but the specific causal agents remain unknown. The study indicated that benign intracranial tumors were unlikely to be work-related.

Design and synthesis of potent and selective inhibitors of integrin VLA-4

The synthesis and identification of a novel series of inhibitors of integrin VLA-4 are described. Their in vitro activity and selectivity against closely related integrins are also presented.

Creating a career ladder for nursing assistants in long-term care

This article describes the development, implementation, and evaluation of a career ladder for certified nursing assistants in long-term care. A career ladder is an effective way to maximize the use of unlicensed workers without changing the skill mix (eg, no loss of licensed nursing positions) and allow the licensed nurse more time to perform higher-level clinical tasks, such as assessments, patient education, and documentation. Implementation of an unlicensed worker career ladder also can improve nursing assistant retention.

Cancer and benign tumor incidence among employees in a polymers research complex

The detection of several intracranial tumors among employees in one building complex (C500) at a petrochemical research facility prompted investigation of a possible workplace cause. This retrospective follow-up study included 1847 subjects, of whom 1735 had worked in C500. Medical records, death certificates, and Illinois State Cancer Registry data confirmed self-reported cancers and tumors. Analyses compared the subjects' cancer and benign intracranial tumor incidence rates with national general population rates. C500 employees had 15% fewer than expected total cancers (92 observed/108 expected; standardized incidence ratio [SIR], 85; 95% confidence interval [95% CI], 69 to 104). An excess of brain cancer (6/2.0; SIR, 302; 95% CI, 111 to 657) was concentrated among white men who had 10 or more years since hire and 5 or more years of C500 employment (4/0.7; SIR, 602; 95% CI, 165 to 1552) and who had worked in a particular building of C500 (5/0.7; SIR, 735; 95% CI, 239 to 1716). An excess of benign intracranial tumors (6/1.6; SIR, 385; 95% CI, 142 to 839) was not restricted to a single type of tumor and was not concentrated in any particular building. Occupational exposure may have caused the increased rate of brain cancer but is a less likely explanation for the elevated rate of benign intracranial tumors.

Global Forum on Safety of Herbal and Traditional Medicine: July 7, 2001, Gold Coast, Australia

This report provides a summary of the background and inputs of various groups who attended the Global Forum on Safety of Herbal and Traditional Medicine conference held in the Gold Coast, Australia, on July 7, 2001. Keynote presentations covered the status of regulation of complementary medicine in Australia and comparative examples from Africa and Bangladesh. There was substantial input about work to date on databases, reflecting the need to have a focus on safety outcomes as a point of direction for the forum. Safety evaluation, which incorporates quality procedures, was identified as another point of focus. Clear evidence for the nonutilization of plants known to contain certain compounds producing deleterious effects was exemplified via data and information on the dangers of ingesting pyrrolizidine alkaloids.

Second harmonic FEL oscillation

We have produced and measured for the first time second harmonic oscillation in the infrared region by a free electron laser. Although such lasing is ideally forbidden, since the gain of a plane wave is zero on axis for an electron beam perfectly aligned with a wiggler, a transverse mode antisymmetry allows sufficient gain in this experiment for lasing to occur. We lased at pulse rates up to 74.85 MHz and could produce over 4.5 W average and 40 kW peak of IR power in a 40 nm FWHM bandwidth at 2925 nm. In agreement with predictions, the source preferentially lased in a TEM01 mode.

Clinical testing results and high patient satisfaction with a new needle-free device for growth hormone in young children

Fifty children ages 4-10 yr with type 1 diabetes mellitus volunteered to participate in a study to evaluate and compare a new needle-free device developed for growth hormone delivery. Children answered descriptive questions related to nervousness and worry, hurt or pain, redness or bleeding, and stinging and wetness. Choices for answers for each of these five questions were none, a little, or a lot. None or a little was also combined to give a minimal category. Children also answered four questions that compared the needle-free device to their morning insulin needle injection in reference to ease of use, pain, nervousness, and overall preference. Half the children had single comfort rings inserted to increase the injection pressure. Results indicated no difference in question responses with or without pressure rings. Pain (92%), erythema (96%), worry (90%), stinging (86%) and wetness (96%) were minimal and significant (0.001 > p < 0.03) following all questions. Results of the comparative questionnaire indicated that the device was easier (p < 0.03) to use than needles and significantly preferred (p < 0.001) in 74% of children under age 10.

Cancer incidence among employees at a petrochemical research facility

This investigation evaluated cancer incidence among workers at a petrochemical research facility in Illinois. A cluster of brain cancer and other intracranial tumors had occurred at the facility before the study began. The subjects were 5641 people who had worked at the facility from 1970 through 1996 and who had lived in Illinois at any time between 1986 and 1997. Data on cancer cases came primarily from the Illinois State Cancer Registry. Analyses compared the 1986-to-1997 cancer incidence rates of employees with Illinois general population rates. Subjects had 18% fewer than expected total cancers (125 observed/153 expected cases; standardized incidence ratio [SIR], 82; 95% confidence interval [CI], 68 to 98), which was primarily attributed to a large deficit of lung cancer (10/26; SIR, 39; CI, 19 to 72). Brain cancer was increased in the overall study group (6/2.7; SIR, 222; CI, 81 to 484). This excess was restricted to white men who were scientists or technicians for one of the three companies at the facility (6/0.8; SIR, 750; CI, 275 to 1633); all cases in this group had worked in the "500 building complex" (6/0.6; SIR, 968; CI, 355 to 2106). Subjects also had an increased incidence of thyroid cancer (7/2.6; SIR, 265; CI, 106 to 546) that was not concentrated in particular occupational or building groups. The brain cancer incidence patterns indicated that an unidentified occupational exposure might have been responsible for the excess. Chance, socioeconomic factors leading to better case detection in facility employees than in the general population, and confounding by potential nonoccupational risk factors are plausible explanations of the observed increase in thyroid cancer.

Role of the macrophage galactose lectin in the uptake of desialylated LDL

Desialylated low density lipoprotein (LDL) is rapidly taken up and accumulated by both peripheral blood monocytes and cells isolated from human arterial intima consisting predominantly of smooth muscle cells. It is shown that thioglycollate (TG)-elicited mouse macrophages and mouse peritoneal macrophages stimulated with lipopolysaccharide (LPS) show increased expression of a membrane-bound, galactose-specific lectin that could be responsible for this uptake. In LPS-stimulated macrophages accumulation of desialylated LDL is increased ca. 2.6-fold. Accumulation of acetylated LDL in the same cells is reduced, suggesting that the galactose-specific lectin might be responsible for the uptake of desialylated LDL. Transfection of cells with the mouse macrophage Gal/GalNAc-specific lectin (MMGL) increased their capacity to take up asialofetuin (ASF) and, to a smaller extent, desialylated LDL. The uptake of desialylated LDL was small, most likely due to the high k(d) of MMGL for biantennary oligosaccharides as found on LDL, and low concentration of LDL achieved in tissue culture experiments. The data suggest that the expression of galactose-specific lectins can be elevated under inflammatory conditions, and that these receptors could contribute to foam cell formation under conditions of high desialylated LDL concentration, as might be found in arterial intima.

Visually-guided irrigation in patients with early knee osteoarthritis: a multicenter randomized, controlled trial

OBJECTIVE

To determine if visually-guided arthroscopic irrigation is an effective therapeutic intervention in patients with early knee osteoarthritis.

DESIGN

Ninety patients with knee osteoarthritis were randomized in a double-blind fashion to receive either arthroscopic irrigation with 3000 ml of saline (treatment group) or the minimal amount of irrigation (250 ml) required to perform arthroscopy (placebo group). The primary outcome variable was aggregate WOMAC score.

RESULTS

The study did not demonstrate an effect of irrigation on arthritis severity as measured by aggregate WOMAC scores, the primary outcome variable; the mean change in aggregate WOMAC score at 12 months was 15.5 (95% CI 7.7, 23.4) for the full irrigation group compared to 8.9 (95% CI 4.9, 13.0) for the minimal irrigation group (P=0.10). Full irrigation did have a statistically significant effect on patients' self-reported pain as measured by the WOMAC pain subscale and by a visual analog scale (VAS) (the secondary outcome variables). Mean change in WOMAC pain scores decreased by 4.2 (95% CI -0.9, 9.4) for the full irrigation group compared with a mean decrease of 2.3 (95% CI -0.1, 4.7) in the minimal irrigation group (P=0.04). Mean VAS pain scores decreased by 1.47 (95% CI -1.2, 4.1) in the full irrigation group compared to a mean decrease of 0.12 (95% CI 0.0, 0.3) in the minimal irrigation group (P=0.02). A hypothesis-generating post-hoc analysis of the effect of positively birefrigent intraarticular crystals showed that patients with and without intraarticular crystals had statistically significant improvements in pain assessments and aggregate WOMAC scores at 12 months; patients with crystals had statistically greater improvements in pain.

CONCLUSIONS

Visually-guided arthroscopic irrigation may be a useful therapeutic option for relief of pain in a subset of patients with knee OA, particularly in those who have occult intraarticular crystals.