Household fuel use and latent tuberculosis infection in a Nepali population.

BACKGROUND: The risk of developing latent tuberculosis infection (LTBI) associated with cooking with solid fuels is unknown. This study examined the relationship between household fuel uses and LTBI in adults living in Nepal, a country with a high incidence of tuberculosis. METHODS: Participants were 1088 adults aged 18-70 years, members of the control group of a population-based case-control study of pulmonary TB (PTB) in people without previous TB, living in Kaski and neighboring districts of Nepal. Participants were interviewed in their homes with a standardized questionnaire. Blood samples were tested for LTBI using an interferon-gamma release assay. Multivariate unconditional logistic regression was used to examine associations between household fuel sources and LTBI. RESULTS: The overall prevalence of LTBI in the study population was 36%. Using liquefied petroleum gas (LPG) as the baseline cooking fuel type, the adjusted odds ratio (aOR) for using a primary wood cookstove was 1.13 (95%CI: 0.73,1.77) for all participants and, in women only, 1.14 (0.62, 2.09). Corresponding figures for biogas stoves were 0.64 (0.34,1.20) and 0.59 (0.24,1.45), respectively. Household sources of air pollution positively associated with LTBI included traditional oil lamps (diyos) used during power outages, for which the aOR in all participants was 2.53 (1.20, 5.31), although the number of users was small. Use of candles for lighting was also associated with increased risk of LTBI among men (aOR = 1.61, 95% CI:1.01, 2.56). CONCLUSIONS: No association was found between use of wood for cooking and LTBI. However, there was some evidence that biogas cookstoves were associated with reduced odds of LTBI. Some exposures at the time of actual infection will have been different than the current exposures used in the analysis, biasing results towards the null. Results are sufficient for the use of diyos to be discouraged for lighting purposes. Overall, results suggest that household cooking fuel use is likely to have more effect on moving from the infected state to PTB than on becoming infected with the M. tuberculosis complex. Further research, including longitudinal studies with serial LTBI testing would be useful to more accurately assess the relationships between exposures and infection.

Household fuel use and pulmonary tuberculosis in western Nepal: A case-control study.

BACKGROUND: Whether cooking with solid fuels, as occurs widely in developing countries, including Nepal, is a risk factor for pulmonary tuberculosis (PTB) is uncertain. Epidemiologic studies have produced variable results. This case-control study sought to resolve this issue with a large sample size and a population-based control group. METHODS: PTB cases (N = 581), aged 18-70 were recruited from diagnostic centers in Kaski and neighboring districts of Nepal. Population-based controls (N = 1226) were recruited. Persons who had previously been diagnosed with TB were excluded. Questionnaires were administered at participants' homes. RESULTS: Using liquefied petroleum gas (LPG) as the cookstove reference fuel, for women the odds ratio (OR) for having a primary cookstove that used wood was 0.21 (95% CI: 0.08,0.52); for men the corresponding OR was 0.80 (0.37, 1.74). For biogas, the OR for women was 0.24 (0.06,0.87) and for men, 1.41 (0.61, 3.23). CONCLUSIONS: The unexpected finding of a higher risk for women using LPG cookstoves, relative to wood or biogas-burning cookstoves, may be attributable to excluding persons with prior TB. A possible explanation is that emissions, such as ultrafine particles, formed during LPG combustion promote PTB manifestation in infected people who have not previously had PTB. The damage from the initial PTB leaves them susceptible to the PTB-promoting effects of smoke from wood fires. Further studies, excluding participants who have previously had TB are needed to confirm these findings. Use of exhaust hoods to the outdoors for all stoves, well-ventilated kitchens, and gas stoves raised above ground would reduce exposures.

Low 25-Hydroxyvitamin D and Myofascial Pain: Association of Cancer, Colon Polyps, and Tendon Rupture.

BACKGROUND: Myofascial pain that has been associated with cancer and increased risk of morbidity and mortality in cancer patients is intrinsically associated with low magnesium and low 25-hydroxyvitamin D (25(OH)D). Therefore, this physical finding was used as a clinical diagnostic proxy. OBJECTIVE: The objective of this study was to assess the association and prevalence of disease in individuals with myofascial pain and low 25(OH)D in a county with low magnesium in the drinking water. DESIGN: This is a retrospective cross-sectional study of a chart review of 269 subjects to assess subjects presenting with myofascial pain (assessed by tender trigger points) and 25(OH)D concentrations below 30 ng/mL or a history of 25(OH)D deficiency compared to those without these exposures. RESULTS: The association between the exposure of low 25(OH)D levels and myofascial pain was compared to all cancers, colon polyps, and tendon ruptures. The odds of having cancer with the combined exposures was 10.14 times the odds of not having either exposure (95% confidence interval [CI], 5.08, 20.25, p < 0.001). For adenomatous colon polyps, the odds ratio (OR) was 7.24 (95% CI, 3.83, 13.69, p < 0.001), and for tendon rupture, the OR was 8.65 (95% CI, 3.76, 19.94, p < 0.001). Of 80 subjects who had both myofascial pain and 25(OH)D less than 30 ng/mL, 74 were tested for red blood cell (RBC) magnesium. Half of those subjects had RBC magnesium concentrations < 4.6 mg/dL, and 23% had levels below the reference range (4.0-6.4 mg/dL). CONCLUSION: Myofascial pain as assessed by tender trigger points and 25(OH)D deficiency showed a significant association with cancer, adenomatous colon polyps, and tendon rupture. Further studies to verify these results are needed, especially in areas where there is low magnesium in the drinking water.

Lens Opacity and Hydrogen Sulfide in a New Zealand Geothermal Area.

PURPOSE: Hydrogen sulfide (H2S) is a highly toxic gas with well-established, acute irritation effects on the eye. The population of Rotorua, New Zealand, sited on an active geothermal field, has some of the highest ambient H2S exposures in the world. Evidence from ecological studies in Rotorua has suggested that H2S is associated with cataract. The purpose of the present study was, using more detailed exposure characterization, clinical examinations, and anterior eye photography, to more directly investigate this previously reported association. METHODS: Enrolled were 1637 adults, ages 18 to 65, from a comprehensive Rotorua primary care medical register. Patients underwent a comprehensive ophthalmic examination, including pupillary dilation and lens photography to capture evidence of any nuclear opacity, nuclear color, and cortical and posterior subcapsular opacity. Photographs were scored for all four outcomes on the LOCS III scale with decimalized interpolation between the exemplars. H2S exposure for up to the last 30 years was estimated based on networks of passive samplers set out across Rotorua and knowledge of residential, workplace, and school locations over the 30 years. Data analysis using linear and logistic regression examined associations between the degree of opacification and nuclear color or cataract (defined as a LOCS III score ≥2.0) in relation to H2S exposure. RESULTS: No associations were found between estimated H2S exposures and any of the four ophthalmic outcome measures. CONCLUSIONS: Overall, results were generally reassuring. They provided no evidence that H2S exposure at the levels found in Rotorua is associated with cataract. The previously found association between cataract and H2S exposure in the Rotorua population seems likely to be attributable to the limitations of the ecological study design. These results cannot rule out the possibility of an association with cataract at higher levels of H2S exposure.

Assessment of salivary cadmium levels and breast density in the Marin Women's Study.

BACKGROUND: We aimed to determine if salivary cadmium (Cd) levels had any association with breast density, hoping to establish a less invasive cost-effective method of stratifying Cd burden as an environmental breast cancer risk factor. METHODS: Salivary Cd levels were quantified from the Marin Women's Study, a Marin County, California population composite. Volumetric compositional breast density (BDsxa ) data were measured by single x-ray absorptiometry techniques. Digital screening mammography was performed by the San Francisco Mammography Registry. Radiologists reviewed mammograms and assigned a Breast Imaging-Reporting and Data System score. Early morning salivary Cd samples were assayed. Association analyses were then performed. RESULTS: Cd was quantifiable in over 90% of saliva samples (mean = 55.7 pg/L, SD = 29). Women with higher saliva Cd levels had a non-significant odds ratio of 1.34 with BI-RAD scores (3 or 4) (95% CI 0.75-2.39, p = 0.329). Cd levels were higher in current smokers (mean = 61.4 pg/L, SD = 34.8) than former smokers or non-smokers. These results were non-significant. Pilot data revealed that higher age and higher BMI were associated with higher BI-RAD scores (p < 0.001). CONCLUSION: Salivary Cd is a viable quantification source in large epidemiologic studies. Association analyses between Cd levels and breast density may provide additional information for breast cancer risk assessment, risk reduction plans, and future research directions. Further work is needed to demonstrate a more robust testing protocol before the extent of its usefulness can be established.

Bovine ownership and reduced pulmonary tuberculosis risk in Nepal: A case-control study.

This case-control study sought to confirm and investigate in more depth protective associations previously found of bovine (cattle and water buffalo) ownership with reduced risk of both pulmonary tuberculosis (PTB) and latent tuberculosis infection (LTBI) in humans. The study recruited male and female PTB cases from a diagnostic centre and a frequency-matched community-based control group in Kaski District, Nepal. Controls were tested for LTBI status and a separate nested case-control study was conducted based on LTBI status. Data were collected on participant household animal ownership. Using logistic regression, animal ownership was investigated for associations with both PTB and LTBI. Data were obtained from 570 PTB cases and 1,224 controls, the latter group providing 396 LTBI-positive and 692 LTBI-negative subjects. Results provided evidence of decreased odds of both PTB and LTBI positivity associated with owning bovines. The evidence was strongest for protection against infection, rather than activation of infection to PTB. Effects were strongest in women, who usually manage the animals in Nepal, and there were exposure-response relationships with numbers of bovines owned. Results suggest that exposure to bovines is protective against LTBI and PTB. A possible mechanism involves boosting the effect of BCG (Bacillus Calmette-Guerin) vaccination, particularly in protecting against tuberculous infection. Additional studies with more extensive data collection are needed to confirm the observed associations.

Biomass Fuel Use and Cardiac Function in Nepali Women.

Background: Exposure to household air pollution (HAP) from cooking with biomass fuel affects billions of people. We hypothesized that HAP from woodsmoke, compared to other household fuels, was associated with adverse cardiovascular outcomes, of which there have been few studies. Methods: A cross-sectional study was completed in 299 females aged 40-70 years in Kaski District, Nepal, during 2017-18. All participants underwent a standard 12-lead ECG, ankle and brachial systolic blood pressure measurement, and 2D color and Doppler echocardiography. Current stove type was confirmed by inspection. Blood pressure, height, and weight were measured using a standardized protocol. Hypertension was defined as ≥140/90 mmHg or prior diagnosis. Hemoglobin A1c (HbA1c) was obtained, with diabetes mellitus defined as a prior diagnosis or HbA1C ≥ 6.5%. We used adjusted linear and logistic multivariable regressions to examine the relationship of stove type with cardiac structure and function. Results: The majority of women primarily used liquified petroleum gas (LPG) stoves (65%), while 12% used biogas, and 23% used wood-burning cook-stoves. Prevalence of major cardiovascular risk factors was 35% with hypertension, 19% with diabetes mellitus, and 15% current smokers. After adjustment, compared to LPG, wood stove use was associated with increased indexed left atrial volume (ß = 3.15, 95% CI 1.22 to 5.09) and increased indexed left ventricular end diastolic volume (ß = 7.97, 95% CI 3.11 to 12.83). There was no association between stove type and systemic hypertension, left ventricular mass, systolic dysfunction, diastolic dysfunction, pulmonary hypertension, abnormal ankle-brachial index, or clinically significant ECG abnormalities. Conclusion: Biomass fuel use was associated with increased indexed left atrial volume and increased indexed left ventricular diastolic volume in Nepali women, suggesting subclinical adverse cardiac remodeling from HAP in this cross-sectional study. We did not find evidence of an association with hypertension or typical cardiac sequelae of hypertension. Future studies to confirm these results are needed.

Hexane exposure and persistent peripheral neuropathy in automotive technicians.

Automotive technicians are commonly exposed to organic and chlorinated solvents, particularly through use of cleaning products. Mainly during the period 1989-2002, n-hexane was a component of some of these products. In other occupational contexts, n-hexane has been shown to be a cause of peripheral neuropathy. The purpose of the present study was to investigate whether previous exposures to low concentrations of n-hexane were a cause of persistent peripheral neuropathy in automotive technicians. Enrolled in the study were 830 San Francisco Bay Area automotive technicians. Each participant underwent a battery of tests to investigate peripheral nervous system impairment. Test results regressed against estimated hexane and total solvent exposures showed only limited evidence of association with solvent exposures. Exposures to both hexane and general solvents were well below their occupational exposure limits. Generally, our results provide reassurance about persistent peripheral neuropathic effects in automotive technicians who previously used hexane-containing automotive cleaning products. This may reflect repair processes, since the exposures occurred some years previous to the study. However, we cannot exclude the possibility that the absence of observed effect in this study may be attributable to low exposures, exposure misclassification and/or the healthy worker survivor effect.

Monopolar radiofrequency treatment of the eyelids: a safety evaluation.

BACKGROUND: Monopolar radiofrequency (RF) energy has been used to successfully accomplish noninvasive skin tightening of the face, abdomen, and extremities. Owing to concerns about injury to the eye itself, monopolar RF treatment of the eyelids has not been feasible. OBJECTIVE: The objective was to evaluate the safety of a novel 0.25-cm(2)"shallow" treatment tip for noninvasive tightening of eyelid skin. METHODS AND MATERIALS: This was a tripartite study that began with an animal model to evaluate soft tissue effects and temperature change at the ocular surface. Findings were then extrapolated to ex vivo evaluation of human eyelids and ultimately to an in vivo human eyelid safety study. RESULTS: The animal studies demonstrated that the 0.25-cm(2) treatment tip could be used safely on eyelids in conjunction with appropriate ocular protection. The ex vivo human eyelid studies confirmed that, at typical treatment settings, the shallow treatment tip did not produce frank eyelid injury. The in vivo human studies confirmed that, at the tested settings, the novel treatment tip did not injure the eyelids or eyes. CONCLUSION: If used properly, the 0.25-cm(2) treatment tip can be safely used on human eyelids.

Ambient geothermal hydrogen sulfide exposure and peripheral neuropathy.

The mechanism of toxicity of hydrogen sulfide (H2S) gas is thought mainly to operate through effects on the nervous system. The gas has high acute toxicity, but whether chronic exposure causes effects, including peripheral neuropathy, is yet unclear. The city of Rotorua, New Zealand, sits on an active geothermal field and the population has some of the highest measured ambient H2S exposures. A previous study in Rotorua provided evidence that H2S is associated with peripheral neuropathy. Using clinical methods, the present study sought to investigate and possibly confirm this association in the Rotorua population. The study population comprised 1635 adult residents of Rotorua, aged 18-65. Collected data relevant to the peripheral neuropathy investigation included symptoms, ankle stretch reflex, vibration sensitivity, as measured by the timed-tuning fork test and a Bio-Thesiometer (Bio-Medical Instrument Co., Ohio), and light touch sensitivity measured by monofilaments. An exposure metric, estimating time-weighted H2S exposure across the last 30 years was used. Principal components analysis was used to combine data across the various indicators of possible peripheral neuropathy. The main data analysis used linear regression to examine associations between the peripheral nerve function indicators and H2S exposure. None of the peripheral nerve function indicators were associated with H2S exposure, providing no evidence that H2S exposure at levels found in Rotorua is a cause of peripheral neuropathy. The earlier association between H2S exposure and peripheral neuropathy diagnoses may be attributable to the ecological study design used. The possibility that H2S exposure misclassification could account for the lack of association found cannot be entirely excluded.

Histological and ultrastructural evaluation of the effects of a radiofrequency-based nonablative dermal remodeling device: a pilot study.

BACKGROUND: Many light- and laser-based systems are used to reduce cutaneous wrinkles, and some have been shown to stimulate dermal collagen production. Using the ThermaCool TC radiofrequency device to treat bovine tendon and human abdominal skin, we documented the cutaneous effects of a radiofrequency-based system for nonablative treatment. OBSERVATIONS: Electron microscopy of bovine tendon treated at varied heat and cooling settings revealed collagen fibrils with increased diameter and loss of distinct borders as deep as 6 mm. Human skin treated at varied heat and cooling settings and examined by means of routine light microscopy demonstrated no significant changes in the epidermis or dermal ground substance immediately after treatment; there was scattered mild perivascular and periadnexal inflammation. Three and 8 weeks after treatment, no observable changes were noted. Ultrastructural analysis, however, disclosed isolated, scattered areas of collagen fibrils with increased diameter and loss of distinct borders. In addition, Northern blot analysis demonstrated an increase in collagen type I messenger RNA steady-state expression. CONCLUSIONS: Our findings suggest that collagen fibril contraction occurs immediately after treatment and gives rise to tissue contraction and thermally mediated wounding, which induces new collagen production.

Effect of monopolar radiofrequency treatment over soft-tissue fillers in an animal model: part 2.

BACKGROUND AND OBJECTIVE: Monopolar radiofrequency (RF) treatment is used by physicians to heat skin and promote tissue tightening and contouring. Cosmetic fillers are used to soften deep facial lines and wrinkles. Patients who have had dermal fillers implanted may also benefit from or are candidates for monopolar RF skin tightening. This study examined the effect of RF treatment on various dermal filler substances. This is the second part of a two-part study. STUDY DESIGN/MATERIALS AND METHODS: A juvenile farm pig was injected with dermal fillers including cross-linked human collagen (Cosmoplast), polylactic acid (PLA) (Sculptra), liquid injectable silicone (Silikon 1000), calcium hydroxylapatite (CaHA) (Radiesse), and hyaluronic acid (Restylane). Skin injected with dermal fillers was RF-treated using a 1.5-cm2 treatment tip and treatment levels typically used in the clinical setting. Fillers were examined histologically 5 days, 2 weeks, or 1 month after treatment. Histological specimens were scored for inflammatory response, foreign body response, and fibrosis in order to assess the effect of treatment on early filler processes, such as inflammation and encapsulation. RESULTS: Each filler substance produced a characteristic inflammatory response. No immediate thermal effect of RF treatment was observed histologically. RF treatment resulted in statistically significant increases in the inflammatory, foreign body, and fibrotic responses associated with the filler substances. CONCLUSIONS: Monopolar RF treatment levels that are typically used in the clinical setting were employed in this animal study. RF treatment resulted in measurable and statistically significant histological changes associated with the various filler materials. Additional clinical and histological studies are required to determine the optimal timing of monopolar RF treatment and filler placement for maximal potential aesthetic outcome.

Treatment of hypertrophic scars and keloids with a radiofrequency device: a study of collagen effects.

BACKGROUND AND OBJECTIVE: To determine the efficacy and safety of the ThermaCool TC radiofrequency system for treatment of hypertrophic and keloid scars and evaluate treatment associated collagen changes. MATERIALS AND METHODS: Six subjects with hypertrophic and four with keloid scars were treated with the ThermaCool device: one-third of the scar received no treatment (control), one-third received one treatment and one-third received two treatments (4-week interval). Scars were graded before and then 12 and 24 weeks after treatment on symptoms, pigmentation, vascularity, pliability, and height. Biopsies were taken from four subjects with hypertrophic scars and evaluated with hematoxylin and eosin (H & E) staining, multiphoton microscopy, and pro-collagen I and III immunohistochemistry. RESULTS: No adverse treatment effects occurred. Clinical and H & E evaluation revealed no significant differences between control and treatment sites. Differences in collagen morphology were detected in some subjects. Increased collagen production (type III > type I) was observed, appeared to peak between 6 and 10 weeks post-treatment and had not returned to baseline even after 12 weeks. CONCLUSION: Use of the thermage radiofrequency device on hypertrophic scars resulted in collagen fibril morphology and production changes. ThermaCool alone did not achieve clinical hypertrophic scar or keloid improvement. The collagen effects of this device should be evaluated further in order to optimize its therapeutic potential for all indications.

Effects of monopolar radiofrequency treatment over soft-tissue fillers in an animal model.

BACKGROUND AND OBJECTIVES: Monopolar radiofrequency (RF) treatment is used by physicians to tighten and contour the skin of their patients. In many cases, patients have received prior treatment with other aesthetic modalities such as soft-tissue augmentation or they may wish to receive these treatment modalities simultaneously. Together, soft-tissue augmentation and monopolar RF treatment have the potential to restore tissue volume and improve facial laxity. To date, no published studies have documented the effects of RF treatment directly over soft-tissue fillers. STUDY DESIGN/MATERIALS AND METHODS: We examined the tissue interactions of monopolar RF heating with five commonly injected fillers in a juvenile pig model. This is the first part of a two-part study. In this study, the interaction of monopolar RF and filler substances was examined over a period of 4 months. The five soft-tissue fillers examined were cross-linked human collagen (Cosmoplast), hyaluronic acid (Restylane), calcium hydroxylapatite (Radiesse), polylactic acid (Sculptra), and liquid injectable silicone (Silikon 1000). RESULTS: There was no apparent increase in the risk of local burns and no observable effect of RF treatment on filler persistence in the tissue. With monopolar RF treatment, an increase in fibroplasia and collagen deposition surrounding Restylane, Radiesse, and Sculptra was observed. When scored in a blinded fashion, the increase in collagen deposition was statistically significant for Radiesse. CONCLUSIONS: In this animal study, RF treatment had no observed adverse effect on filler collagen responses or persistence. Filler presence did not increase the risk of undesirable thermal effects with monopolar RF treatment. Further clinical studies are required to evaluate the effect of monopolar RF treatment over dermal fillers with respect to aesthetic outcome.