Preoperative Vitamin.D Status and Post-Total Thyroidectomy Hypocalcemia

Introduction

Hypocalcemia is a common complication of total thyroidectomy (TT). This study was designed to investigate the effect of preoperative vitamin.D (Vit.D) status on the occurrence of post-total thyroidectomy hypocalcemia.

Materials and Methods

Patients who underwent TT without parathyroidectomy were divided into three groups based on their preoperative Serum Vit.D levels (<20 ng/ml, 20-30 ng/ml, and ≥30 ng/ml were considered deficient, insufficient, and normal Vit.D levels, respectively). Serum levels of calcium and phosphorus were measured before and 24 hours after surgery in all patients. The patients were examined for clinical symptoms and signs of hypocalcemia postoperatively. In cases with positive clinical symptoms and signs of hypocalcemia and/or calcium levels <8 mg/dl, PTH level was measured before starting calcium infusion, while serum calcium and phosphorus levels were also measured 24 hours later.

Results

Among 100 patients enrolled in this study, 81% were females. The mean age was 36.60±8.32 years. Before surgery, the mean Vit.D level was 26.9±16.89 ng/ml, while 47% of cases had normal Vit.D level, 32% had insufficient vitamin levels, and 21% had Vit.D deficiency. Twenty-four hours after surgery, the calcium (P=0.356) and phosphorus (P=0.743) levels were not significantly different between the three Vit.D groups. A comparison of postoperative PTH levels between the three Vit.D groups showed no significant difference (P=0.596).

Conclusions

Based on our findings, preoperative serum Vit.D levels did not affect postoperative serum calcium levels.

Comparison of Magnesium Status Using 24-h Urine Magnesium Content and Magnesium Fraction Excretion in PCOS with Non-PCOS Control Women: a Cross-sectional Study

Magnesium (Mg) is the second most frequent intracellular cation, having an important role in normal enzyme function and insulin secretion. Polycystic ovarian syndrome (PCOS) is the most prevalent endocrinopathy in women of reproductive age and often associated with insulin resistance. Two systematic reviews and meta-analyses have been conducted to compare mean serum Mg levels between PCOS and control groups. Both studies detected unexplained heterogeneity among input studies and the two conclusions contradict each other, while approximately 1% of total body Mg is present in extracellular fluid (ECF) and serum Mg level does not represent Mg status well. For the first time, we investigated magnesium renal fraction excretion (FEMg) and compared mean values between PCOS and non-PCOS control women. This study is a cross-sectional analysis conducted at an academic medical center. Forty-four women were included in the PCOS group based on the Rotterdam criteria and 50 non-PCOS women were included in the control group. Statistical analysis of the relationship between 24-h urinary Mg content and FEMg, and also physical and metabolic variables, was performed. Main outcome measurements are 24-h urinary Mg content and FEMg. Mean values of 24-h urinary Mg content and FEMg did not significantly differ between PCOS and control groups (P = 0.22 and P = 0.24, respectively). Also, serum Mg levels and Ca/Mg ratio were similar between the groups (P = 0.17 and P = 0.26, respectively). Our data suggested Mg status in the PCOS group was similar to the non-PCOS control group and both were not magnesium deficient. For further investigation, we recommend using FEMg for evaluating Mg status rather than serum Mg levels. Considering collection of background diet is helpful and desired for future studies.

Diagnostic Performance of ACR TI-RADS and ATA Guidelines in the Prediction of Thyroid Malignancy: A Prospective Single Tertiary Center Study and Literature Review

AIM

This study sought to compare two common risk stratification systems in terms of their diagnostic performance for the evaluation of thyroid malignancy.

METHODS

The American College of Radiology (ACR) Thyroid Imaging, Reporting and Data System (TI-RADS) and the American Thyroid Association (ATA) guidelines were compared among 571 thyroid nodules with definitive fine needle aspiration (FNA) cytology or postoperative histopathology. Ultrasound characteristics such as composition, echogenicity, shape, margin, size, and vascularity were assessed for each thyroid nodule. Diagnostic performance measures were determined and compared through receiver operating characteristic (ROC) curves, and decision curve analysis (DCA).

RESULTS

Of 571 nodules, 65 (11.4%) were malignant. The AUC, sensitivity, specificity, positive predictive value, and negative predictive value were 0.691, 49.2%, 84.9%, 29.6%, and 92.8% for ATA guideline, and 0.776, 72.3%, 79.2%, 30.9%, and 95.7%, for ACR TI-RADS, respectively. ACR TI-RADS was more sensitive (p = 0.003), while the ATA guideline was more specific (p < 0.001). DCA demonstrated that the ACR TI-RADS provided a greater net benefit than the ATA guideline. In addition, the net reduction in unnecessary biopsies is higher for ACR TI-RADS than ATA guidelines. The total number of indicated biopsies and unnecessary FNA rates were lower in ACR TI-RADS compared to ATA guideline (293 vs. 527 and 80.2 vs. 87.8). ACR TI-RADS presented no biopsy indication in seven malignant nodules (all categorized as TR2), whereas ATA guideline missed one. Hypoechogenicity was the most significant predictor of malignancy (OR = 8.34, 95% CI: 3.75-19.45), followed by a taller-than-wide shape (OR = 6.73, 95% CI: 3.07-14.77).

CONCLUSIONS

Our findings suggest that each system has particular advantages in the evaluation of thyroid nodules. ACR TI-RADS reduces unnecessary FNA rates, however, malignant nodules categorized as TR2 might be missed using this system. Further evaluation of this group of nodules using Doppler and other ultrasound modalities is recommended.

Correlation of glycemic control with salivary oxidative markers in subjects with prediabetes and diabetes: A cross-sectional study

Background and aims

Rising levels of oxidative stress play an important role in the pathogenesis of type 2 diabetes mellitus. This study aimed to some assess salivary antioxidants in patients with type 2 diabetes, prediabetes, and healthy control. We also assessed the potential clinical relevance of salivary antioxidants with glycemic control.

Methods

This cross-sectional study included 30 prediabetes, 31 type 2 diabetes, and 39 sex-matched normoglycemic individuals. To assess the salivary oxidative status, we measured the levels of malondialdehyde (MDA), superoxide dismutase (SOD), the total antioxidant capacity (TAC), and uric acid (UA) by spectrophotometry.

Results

Salivary MDA levels were significantly higher in individuals with diabetes compared to prediabetes, and control groups (p = 0.001). MDA and SOD were significantly correlated with fasting blood sugar (FBS) and HbA1C (p < 0.001, r = 0.43, p < 0.001, r = 0.34, and p = 0.003, r = 0.29 p = 0.01, r = 0.23 respectively). Salivary TAC was also significantly correlated with FBS (p = 0.02, r = 0.23). Furthermore, salivary MDA was an independent determinant of type 2 diabetic patients compared to healthy subjects (p = 0.04). According to the cutoff point in the ROC curve, the MDA index was below 2.8 in 82.1% of the controls (specificity), and it was above 2.8 in 64.2% of the Individuals with diabetes (sensitivity).

Conclusion

The simultaneous assessment of salivary oxidative and antioxidant factors, revealed weak but a significant positive association between MDA and glycemic status in diabetes. However, further investigations are required to confirm our results.

Accuracy of fine-needle aspiration cytopathology to differentiate malignant and benign thyroid nodules with ≥4 cm diameter: A retrospective study

BACKGROUND

Thyroid nodules (TN) are commonly present in the general population and are usually pathologically benign. An initial diagnosis with fine-needle aspiration (FNA) cytopathology could help clinical decision-making with fewer complications. As the previous studies suggest surgical procedures for >4 cm TNs, we aimed to investigate the accuracy of preoperative FNA cytology to predict malignancy risk in these nodules in a sample of the Iranian population.

METHODS

Patients with ≥4 cm TNs who had preoperative FNA cytology, underwent nodulectomy and had a histopathological report were included. Each patient's preoperative demographic, ultrasonographic, and cytology data were gathered. After surgery, resected samples were assessed pathologically and diagnosed as benign or malignant. Finally, data were analyzed to evaluate the presurgical accuracy of the FNA cytology.

RESULTS

We identified 41 (51.25%) patients with malignant legions among our study population (N = 80). The pathology reports were indeterminate in 3 patients with follicular neoplasm. Bethesda scores were substantially higher in patients with malignancy. The sensitivity, specificity, and false-negative rate of FNA cytology reports using the Bethesda system were 73.7%, 74.2%, and 26.3%, respectively. There was no association between malignancy and TNs' size, neither their volume nor their highest diameter.

CONCLUSION

FNA cytology is not as sensitive and specific in nodules>4 cm as in smaller ones. However, it can still be used alongside other diagnostic procedures in malignancy screening. Clinicians should make more complex decisions considering various influential factors to avoid missing malignant lesions and reduce diverse probable complications of highly invasive diagnostic surgery. Further prospective research on >4 cm TNs and their multiple features' association with malignancy is required for more precise judgment.

The antihyperglycemic and hypolipidemic effects of Ribes khorassanicum hydro-ethanolic extract co-administration in type 2 diabetic patients: A randomized double blind placebo controlled trial

Objective

The present randomized clinical trial assessed the antihyperglycemic and hypolipidemic effects of hydro-ethanolic extract of Ribes khorassanicum.

Materials and Methods

Eighty type 2 diabetic patients were randomly allocated to placebo or intervention groups and respectively received placebo or extract capsules (700 mg, bid) beside their conventional medication for 3 months. Patients' blood pressure and blood levels of fasting blood glucose (FBS), glycosylated hemoglobin (HbA1c), 2 hr postprandial glucose (2hPPG), triglyceride, total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were measured at the beginning of the study and after 3 months of treatment. For determination of plant safety, liver enzymes (SGOT and SGPT) and kidney function (in terms of urea, creatinine, and microalbumin levels) were assessed and patients were asked to report adverse effects.

Results

The R. khorasanicum hydro-ethanolic extract supplementation significantly decreased the levels of FBS, total cholesterol, triglyceride, and LDL-C in the extract group compared to the placebo group (p<0.05-p<0.01). However, 2hPPG, HbA1c, HDL-C, SGOT, SGPT, urea, creatinine, and urine microalbumin values were not significantly different between the placebo and the extract groups. No adverse effects were reported by the patients.

Conclusion

Co-supplementation of diabetic patients with R. khorasanicum extract ameliorated hyperglycemia and hyperlipidemia without causing any adverse effects; therefore, the plant extract may be recommended as a complementary therapy to improve diabetes-induced metabolic disturbances.

A systematic review of gut microbiota composition in observational studies of major depressive disorder, bipolar disorder and schizophrenia

The emerging understanding of gut microbiota as 'metabolic machinery' influencing many aspects of physiology has gained substantial attention in the field of psychiatry. This is largely due to the many overlapping pathophysiological mechanisms associated with both the potential functionality of the gut microbiota and the biological mechanisms thought to be underpinning mental disorders. In this systematic review, we synthesised the current literature investigating differences in gut microbiota composition in people with the major psychiatric disorders, major depressive disorder (MDD), bipolar disorder (BD) and schizophrenia (SZ), compared to 'healthy' controls. We also explored gut microbiota composition across disorders in an attempt to elucidate potential commonalities in the microbial signatures associated with these mental disorders. Following the PRISMA guidelines, databases were searched from inception through to December 2021. We identified 44 studies (including a total of 2510 psychiatric cases and 2407 controls) that met inclusion criteria, of which 24 investigated gut microbiota composition in MDD, seven investigated gut microbiota composition in BD, and 15 investigated gut microbiota composition in SZ. Our syntheses provide no strong evidence for a difference in the number or distribution (α-diversity) of bacteria in those with a mental disorder compared to controls. However, studies were relatively consistent in reporting differences in overall community composition (β-diversity) in people with and without mental disorders. Our syntheses also identified specific bacterial taxa commonly associated with mental disorders, including lower levels of bacterial genera that produce short-chain fatty acids (e.g. butyrate), higher levels of lactic acid-producing bacteria, and higher levels of bacteria associated with glutamate and GABA metabolism. We also observed substantial heterogeneity across studies with regards to methodologies and reporting. Further prospective and experimental research using new tools and robust guidelines hold promise for improving our understanding of the role of the gut microbiota in mental and brain health and the development of interventions based on modification of gut microbiota.

The role of diet quality and dietary patterns in predicting muscle mass and function in men over a 15-year period

A growing body of evidence suggests that diet quality may predict muscle health. This study found that a "Traditional" dietary pattern predicted greater muscle mass, and an anti-inflammatory diet predicted greater muscle mass and better muscle function over 15 years. These findings reinforce the importance of optimising dietary behaviours for healthy ageing.

INTRODUCTION

Research investigating the roles of individual nutrients in muscle health fails to account for the synergistic relationships between foods and nutrients. This study aimed to investigate the predictive value of diet quality and dietary patterns for muscle mass and function in men over a 15-year period.

METHODS

This longitudinal study was conducted in 522 men from the Geelong Osteoporosis Study with complete dietary and muscle mass or muscle function data at both baseline and 15-year follow-up assessments. Dietary exposures were extracted from food frequency questionnaires and included the Australian Recommended Food Score, the Dietary Inflammatory Index (DII®), and three a posteriori dietary patterns: Plant-focused, Western, and Traditional (Anglo-Australian). Outcome variables included dual-energy X-ray absorptiometry-derived skeletal muscle index (SMI) and muscle function measured with the timed up-and-go (TUG) test.

RESULTS

An anti-inflammatory diet and higher scores on a Traditional dietary pattern both predicted greater SMI ((B: -0.04 (95%CI -0.08, -0.00) kg/m²) and (B: 0.12 (95%CI 0.04, 0.20) kg/m²), respectively), while a pro-inflammatory diet predicted slower TUG (B: 0.11 (95%CI 0.001, 0.21) sec) over the 15-year follow-up period. These associations remained significant following adjustment for confounding variables. There were no associations observed for other dietary exposures.

CONCLUSION

A Traditional dietary pattern higher in vegetables, wholegrain cereals, and animal protein was associated with greater skeletal muscle mass, and an anti-inflammatory diet, also rich in vegetables, fruit, and wholegrain cereals, was associated with greater skeletal muscle mass and better muscle function over 15 years.

Assessment of insulin resistance in patients with primary hyperparathyroidism before and after Parathyroidectomy

Background

Primary hyperparathyroidism (PHPT) can lead to renal and skeletal disorders, as well as insulin resistance and impaired glucose metabolism. The current study aimed to assess the effects of parathyroidectomy on insulin resistance in patients with PHPT.

Materials and Methods

The present study was conducted on 65 patients with PHPT and indications for parathyroidectomy who were referred to the endocrinology clinics of Mashhad University of Medical Sciences. Thereafter, the demographic characteristics of the patients were recorded. Blood tests, including haemoglobin A1c (HbA1c), fasting blood glucose (FBG) and insulin levels, were assessed one week before and three months after the surgery. The insulin resistance score (HOMA‐IR) was calculated and compared using the relevant formula.

Results

A total of 65 participants with a mean age of 45.44 ± 9.59 years were included in the current study. In one‐month postoperative tests, mean scores of FBG (p < .05), insulin level (p < .05) and HbA1c (p < .05) were significantly reduced. Moreover, the HOMA‐IR index decreased in 51 patients after the surgery.

Conclusion

According to our findings, parathyroidectomy can be effective in the reduction of insulin resistance and corresponding complications in patients with PHPT in the present short‐term study. However, it has yet to be confirmed as a treatment method for insulin resistance in these patients. Future long‐term studies are required to be done to investigate the effect of parathyroidectomy on insulin resistance.

The present study aimed to assess the effects of parathyroidectomy on insulin resistance in patients with primary hyperparathyroidism (PHPT). The present study was conducted on 65 patients with PHPT and indications for parathyroidectomy. Demographic characteristics of the patients were recorded. Blood tests, including fasting blood sugar (FBS), haemoglobin A1c (HbA1c) and insulin levels, were assessed one week before and three months after the surgery. The Homeostatic Model Assessment for Insulin Resistance (HOMA‐IR index) was calculated. In one‐month postoperative tests, mean scores of FBS (p < .05), insulin level (p < .05) and HbA1c (p < 0.05) were significantly reduced compared to these variables prior to the surgery. Moreover, the HOMA‐IR index decreased in 51 patients after the surgery. As evidenced by the results of the present study, parathyroidectomy can be effective in reducing insulin resistance and its complications in patients with primary hyperparathyroidism (PHPT).

Case series: Rare cases of thyroid storm in COVID-19 patients

Thyroid storm is an uncommon life-threatening thyroid dysfunction which was observed for the first time among patients infected with Coronavirus 2019 (COVID-19). The diagnosis and treatment of the rare thyroid distinctions such as thyroid storm in COVID-19-infected patients should be critically considered alongside common treatments of COVID-19 infection.

The effect of levothyroxine in comparison with placebo on serum osteocalcin levels in patients with subclinical hypothyroidism

BACKGROUND AND OBJECTIVE

Subclinical hypothyroidism can potentially develop to overt hypothyroidism. Thyroid hormones have substantial roles in metabolism and glucose homeostasis and thus are closely related to determinant factors of metabolic syndromes, such as obesity and insulin resistance. Osteocalcin is considered a predictor of metabolic conditions in thyroid diseases. This study aimed to investigate the effect of levothyroxine vs. placebo on serum osteocalcin levels in patients with subclinical hypothyroidism.

METHODS

This randomized clinical trial was performed on 30 patients with subclinical hypothyroidism who were referred to the endocrine clinics of Ghaem and Imam Reza hospitals in Mashhad, Iran. After giving informed consent, patients were randomly divided into intervention (50 µg/day levothyroxine for 2 months) and control (placebo) groups. Serum levels of osteocalcin, thyroid hormones, lipid profile, insulin, and fasting glucose, as well as other clinical and anthropometric data, were measured at baseline and at the end of the study. SPSS was used to analyze the data and P<0.05 was considered significant.

RESULTS

Mean age in the intervention and control groups was 35.07 ± 9.94 and 31.30 ± 4.30, respectively (P=0.20). There was no significant difference between osteocalcin levels before and after the intervention in either of the groups (P=0.54). TSH level was significantly decreased in the levothyroxine group after the intervention (P<0.01). T4 level was significantly increased in the intervention group (P=0.02).

CONCLUSION

Levothyroxine had no significant effect on increasing the levels of serum osteocalcin in patients with subclinical hypothyroidism. We have registered the trial in the Iranian registry of clinical trials (IRCT) with the registration code IRCT20171129037677N1.

Diagnostic Value of CK19, HBME-1 and TROP2 Biomarkers in Identification of Different Types of Thyroid Follicular Neoplasms

Thyroid malignancies are found in 7% to 15% of all thyroid nodules. Immunohistochemical markers, including CK19, HBME-1and TROP2, have shown an effective role in identifying these malignancies. Hence, due to the lack of appropriate diagnostic tests for the identification of thyroid neoplasms, in this study, we aimed to determine the diagnostic value of these biomarkers in the identification of different types of follicular thyroid neoplasms. In this cross-sectional study, paraffin-embedded tissue blocks from the surgical resection of patients with thyroid nodules, referring to Imam Reza and Razavi Hospitals of Mashhad in 2017, were studied. Sensitivity, specificity, and positive and negative predictive values of these biomarkers for the identification of different types of follicular thyroid neoplasms were also studied. 129 patients with a mean age of 44.65±12.59 years participated in this study, of whom 101 (78.29%) were women. The most common type of follicular thyroid neoplasm was papillary carcinoma (60.47%). The highest sensitivity (94.87%) and positive predictive value (68.51%) in the detection of follicular neoplasms was observed by CK19 in papillary carcinoma. The sensitivity and positive predictive value of TROP2 in the detection of papillary neoplasms was 93.58% and 75.25%, respectively. In addition, HBME-1 had the highest specificity (72.54 %) and positive predictive value (81.57%) in identifying this neoplasm. The results of this study showed that CK19, HBME-1, and TROP2 had high diagnostic value in the detection of papillary thyroid neoplasms. Although these biomarkers had low diagnostic value in identifying follicular adenoma and carcinoma, given the high negative predictive value, they can be considered as powerful markers in identifying negative cases.

Repurposing a fracture risk calculator (FRAX) as a screening tool for women at risk for sarcopenia

Osteoporosis and sarcopenia share risk profiles, so we tested a fracture risk assessment tool (FRAX) as a screening tool for sarcopenia. FRAX probabilities without bone mineral density predicted sarcopenia with high sensitivity and reasonable specificity. There is potential to use this FRAX as a screening tool for sarcopenia.

PURPOSE

There is a need for simple screening tools for sarcopenia. As osteoporosis and sarcopenia share risk profiles, we tested the performance of a fracture risk assessment tool for discriminating individuals at risk for sarcopenia.

METHODS

In this longitudinal study, FRAX (Australia) probabilities were calculated for 354 women (ages 40-90 years) in the Geelong Osteoporosis Study. Sarcopenia was assessed a decade later using DXA-derived low appendicular lean mass (Lunar; ALM/height² < 5.5 kg/m²) and low handgrip strength (Jamar; HGS < 16 kg), according to EWGSOP2. We determined FRAX probabilities (%) for hip fracture (HF-FRAX) and major osteoporotic fracture (MOF-FRAX), with and without BMD. Area under the receiver operator characteristic (AUROC) curves quantified the performance of FRAX for predicting sarcopenia.

RESULTS

Baseline median (IQR) values for HF-FRAX without BMD were 0.4 (0.1-1.3) and for MOF-FRAX without BMD, 2.4 (1.2-5.2); comparable figures for HF-FRAX with BMD were 0.2 (0.0-0.7) and for MOF-FRAX with BMD, 2.1 (1.1-4.4). At follow-up, sarcopenia was identified for 11 (3.1%) women. When FRAX was calculated without BMD, the AUROC was 0.90 for HF-FRAX and 0.88 for MOF-FRAX. Optimal thresholds were 0.9 for HF-FRAX (sensitivity 90.9%, specificity 62.4%) and 5.3 for MOF-FRAX (sensitivity 81.8%, specificity 71.7%). Calculating FRAX with BMD did not improve the predictive performance of FRAX for sarcopenia.

CONCLUSION

Here we provide preliminary evidence to suggest that FRAX probabilities without BMD might predict sarcopenia with high sensitivity and reasonable specificity. Given that FRAX clinical risk factors are identified without equipment, there is potential to use this or a modified version of the FRAX tool to screen for individuals at risk of sarcopenia.

Evaluation of Serum Level of FGF23 and 1,25(OH)2D3 in Primary Hyperparathyroidism Patients Before and After Parathyroidectomy

Purpose

Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) play critical roles in phosphate homeostasis. To the best of our knowledge, there are limited data on the impact of FGF23 and PTH on serum calcium, 1,25(OH)₂D₃, and phosphate in patients with primary hyperparathyroidism (PHPT). We examined these parameters and their correlations in PHPT patients before and after parathyroidectomy (PTX).

Patients and Methods

In this prospective cohort study, 29 PHPT patients who met the inclusion criteria were selected. The patient’s blood samples were taken three times: before the operation, 24 h after the operation, and 1 week after the operation. The concentrations of serum calcium, FGF23, 1,25(OH)₂D₃, phosphate, PTH, and alkaline phosphatase were measured in a referral laboratory at each of the three steps. Moreover, 25(OH)D was primarily measured just before the surgery.

Results

Of 29 patients included in this study with a mean age of 52.37±12.3 years, majority were females (75.8%). Serum FGF23 and 1,25(OH)₂D₃ levels were high before PTX and decreased after the operation; however, the difference was not statistically significant. FGF23 levels were significantly correlated with 1,25(OH)₂D₃ at each of the three steps (r=0.964, P <0.01; r=0.985, P <0.0; and r=0.976, P <0.05). The variations in calcium, phosphate, creatinine, and PTH were preoperatively and postoperatively significant.

Conclusion

Although 1,25(OH)₂D₃ and FGF23 levels were preoperatively higher in PHPT, their variations were not meaningful. There was a statistically direct significant relationship between 1,25(OH)₂D₃ and FGF23 preoperatively and postoperatively; however, the correlations between FGF23 and calcium, phosphate, and PTH were not significant.

Ectopic Cushing’s Syndrome as the Initial Presentation of Pulmonary Carcinoid Tumor Managed by Etomidate: A Case Report

Ectopic increase of adrenocorticotropic hormone (ACTH) or ectopic Cushing syndrome is a rare initial presentation of small cell carcinoma and carcinoid tumor of the lung. Here, we reported a 36-year-old male with atypical symptoms of Cushing syndrome managed by Etomidate that had a central pulmonary nodule, and pathologic evaluation of pulmonary lobectomy revealed the diagnosis of well-differentiated, low-grade typical carcinoids of lung. © 2019Tehran University of Medical Sciences. All rights reserved. Acta MedIran 2019;57(7):464-467.

Pistacia atlantica Desf. A review of its traditional uses, phytochemicals and pharmacology

Pistacia atlantica is the main herbal medicine that has been widely used in the Middle Eastern and Mediterranean areas since ancient time. Pistacia atlantica has been used for multiple purposes like stomach diseases, renal disorders, wounds and coughs. The aim of this study is to review its botanical characterization, traditional applications, photochemistry effects and pharmacological activities. Data in this review article was gathered from credible pharmacopeias, electronic databases such as Web of Science, Science Direct, PubMed, EMBASE, Scopus, EBSCO, Google Scholar, SID and Iran Medex and textbooks of Persian medicine such as Canon of medicine (Ibn-e Sina, 980-1037 AD) and Makhzan-al-Advia (Aghili, 18th century). The keywords were searched in Persian and English books on medicinal plants and traditional medicine. The results showed that P. atlantica has many medicinal properties such as antioxidant, antidiabetic, antihyperlipidemic, along with others. It can also be effective in gastrointestinal diseases. Thus, different new drugs can be formulated based on P. atlantica for the management of various diseases.

Breast Screening Reminder Letters and Phone Calls to Women in Their Language

Background: BreastScreen Victoria (BSV) provides free breast screening to women aged 40+; targeting women aged 50-74. The program reduces breast cancer-related deaths by up to 28%. BSV aims to ensure equitable participation by all women in the target population. However, women from Arabic and Italian speaking backgrounds have lower breast screening participation compared with English-speaking women. A needs analysis involving consultation with Arabic and Italian speaking women found that invitation letters and calls are important enablers to breast screening, however language is a barrier. Women suggested sending reminder letters and making outbound reminder calls in their language. Aim: The aim of this study was to determine whether, and to what extent, reminder letters and phone calls in language resulted in increased screening rates in Arabic and Italian women. Methods: Two randomized control trials ran in 2017. TRIAL 1: Women due for a routine breast screen who speak Italian or Arabic at home were randomized into one of two trial arms: women in the intervention arm received a reminder letter in language (with the English version enclosed also), and women in the control arm received a reminder letter in English only. 1032 women were included in the study; comprising 322 Arabic and 710 Italian women. TRIAL 2: Lapsed women (had not had a breast screen within 27 months) who speak Italian or Arabic at home were randomized into one of two trial arms: women in the intervention arm received an outbound call in language inviting them to book an appointment; women in the control arm did not receive a call. 219 lapsed screeners were included; comprising 93 Arabic and 126 Italian women Results: TRIAL 1: • Women in the intervention arm more frequently booked (61.2%) compared with the control group (59.8%). However, this difference was not statistically significant. • For Italian women, 64.5% in the intervention group and 66.2% in the control group booked a screening appointment within 30 days of the mail out. Among Arabic women, the rates were 53.1% and 47.5% respectively. TRIAL 2: • Women in the intervention group were 10.7 times more likely to make a booking (42.9%) compared with the control group (4%). The effect was larger for Arabic than for Italian women. Conclusion: Sending reminder letters to Italian and Arabic women in their own language did not result in a statistically significant increase in bookings. Making reminder phone calls to Italian and Arabic women in their own language did result in a large, statistically significant increase in bookings and attendance.

Wide complex tachycardia discrimination using dynamic time warping of ECG beats

BACKGROUND AND OBJECTIVE

Automatic processing and accurate diagnosis of wide complex tachycardia (WCT) arrhythmia groups using electrocardiogram signals (ECG) remains a challenge. WCT arrhythmia consists of two main groups: ventricular tachycardia (VT) and supraventricular tachycardia with aberrancy (SVT-A). These two groups have similar morphologies in the realm of ECG signals. VT and SVT-A arrhythmias originate from the ventricle and atrium, respectively. Hence, inaccurate diagnosis of SVT-A instead of VT can be fatal.

METHODS

In this paper, we present a novel algorithm using dynamic time warping (DTW) to discriminate between VT and SVT-A arrhythmias. This method includes pre-processing, best template search (BTS), and classifier modules. The first module, pre-processing, is responsible for filtering, R-wave detection, and beat detection of ECG signals. The second module, BTS, automatically extracts the minimum possible number of signals as a template from the entire training dataset using an intelligent algorithm. These template signals have the greatest morphological difference, which leads to accurate WCT discrimination. Finally, a 1NN classifier categorizes the test data using DTW distance.

RESULTS

Our proposed method was evaluated on an ECG signal database consisting of 171 subjects. The results showed that the proposed algorithm can accurately discriminate between VT, SVT-A, and normal subjects, and appears to be suitable for future use in clinical application. The obtained accuracy, sensitivity, specificity, and positive predictive values were 93.22%, 88.68%, 96.98%, and 90.27%, respectively.

CONCLUSION

The presented diagnostic method for discriminating VT and SVT-A, using only one ECG lead, is suitable for future clinical use. It can reduce needless therapeutic interventions and minimize risk for patients.

The efficacy of metformin compared with insulin in regulating blood glucose levels during gestational diabetes mellitus: A randomized clinical trial

BACKGROUND

Insulin has been a conventional medication in the treatment of female patients suffering from gestational diabetes mellitus (GDM). However, the need for a large number of insulin injections in these patients causes them a lot of discomforts. Recently, an alternative medication, metformin, has received considerable attention in the treatment of GDM. The aim of this study was to compare the efficacy of metformin and insulin in regulating blood glucose levels and fetal outcomes in GDM.

METHODS

This randomized clinical trial included 286 pregnant women diagnosed with positive GDM at 24-28 weeks of pregnancy. The subjects were randomly divided into two groups of 143 patients, with one group receiving insulin and the other undergoing a treatment plan using metformin. Fasting plasma glucose (FPG), 2-hr plasma glucose (PG) and glycated hemoglobin (HbA1c) were recorded twice a month until delivery. Other variables, including birth delivery method, cause of cesarean section, gestational age at the delivery time, birth trauma, Apgar score, birth weight, admission at neonatal intensive care unit (NICU), and neonatal hypoglycemia were also registered.

RESULTS

Age of mother, body mass index, history of diabetes in the family, previous history of GDM, parity, FPG, 1- and 2-hr PG after meals, and 75-g glucose tolerance test before treatment were not statistically different between the two groups. FPG, PG, and HbA1c did not show significant differences between the two groups after completing the course of treatment. There was also no significant difference between two groups regarding the birth delivery method, the cause of cesarean section, birth trauma, Apgar score, birth weight, admission at NICU, and neonatal hypoglycemia.

CONCLUSION

As mean FPG and 2-hr PG were not significantly different between the two groups, it seems that metformin can be recommended as an effective substitute for insulin in the treatment of GDM. However, there are still some undesirable risk factors with both treatments that may threaten the mother and the newborn.

Effect of Pistacia atlantica kurdica gum on diabetic gastroparesis symptoms: a randomized, triple-blind placebo-controlled clinical trial

BACKGROUND

Gastroparesis is a recognized problem of type 1 and 2 diabetes mellitus that is defined by delayed gastric emptying. Due to insufficient satisfaction of current treatments, the use of complementary and alternative medicine in this field seems essential. According to Persian medicine, Pistacia atlantica gum has proper effect on gastrointestinal disorder specially stomach diseases.

OBJECTIVE

The aim of this study was to assess the effect of Pistacia atlantica gum on diabetic gastroparesis symptoms.

METHODS

A triple-blind randomized placebo-controlled trial on subjects with diabetic gastroparesis was conducted at the clinic of Imam Reza Hospital in Mashhad city in Iran, from November 2016 to May 2017. Fifty-four patients (16.7% males and 83.3% females) enrolled in the 8-week study and were randomly divided into two groups of intervention Pistacia atlantica and placebo groups. Both of the groups had received current dietary advice. Severity of gastroparesis symptoms was assessed with a Gastroparesis cardinal symptom index (GCSI) questionnaire. SPSS software version 16 was used to analyze the data and Generalized Estimating Equation (GEE) model, Independent-samples t-test, Paired-samples t-test, Mann-Whitney U test, and Wilcoxon signed-rank test were used to assess variables.

RESULTS

All gastroparesis symptoms of patients (14.6% diabetes type 1 and 85.4% diabetes type 2) including nausea/vomiting, postprandial fullness/early satiety, and bloating were significantly declined in each group during study (p<0.0001). Pistacia atlantica gum significantly reduced severity of gastroparesis symptoms including Postprandial fullness/early satiety (p=0.04), Bloating (p<0.0001), and GCSI scores (p=0.001) versus placebo. Systolic blood pressure (p=0.006), BMI (p=0.018), and HbA1c (p=0.038) significantly decreased in the Pistacia atlantica group after the intervention.

CONCLUSION

This study showed that daily consumption of Pistacia atlantica gum for one month improves diabetic gastroparesis symptoms.

TRIAL REGISTRATION

The trial was registered at the Iranian Registry of Clinical Trials (http://www.irct.ir) with the code of IRCT2016110630739N1.

FUNDING

This study was supported by funding (grant no.: 950153) from the Mashhad University of Medical Sciences Research Council, Mashhad, Iran.

Patient centric measures for a patient centric era: Agreement and convergent between ratings on The Patient Global Impression of Improvement (PGI-I) scale and the Clinical Global Impressions – Improvement (CGI-S) scale in bipolar and major depressive disorder

Background:

Concordant with an increased emphasis on consumer engagement, the Patient Global Impression Scale of Improvement (PGI-I) is commonly used as an outcome measure in studies evaluating the efficacy of treatments in medical and psychiatric conditions with subjective symptom domains. The current study evaluated the agreement between PGI-I and Clinician Global Impression Scale of Improvement (CGI-I) ratings and convergent validity of PGI-I among individuals with bipolar or major depressive disorders.

Method:

Data were derived from three double-blind, placebo-controlled, multicentre studies conducted from 2007 to 2015 among adult individuals (N = 472). Clinicians were asked to rate participants symptoms using the CGI-I as well as severity of depression by the Montgomery-Åsberg Depression (MADRS), quality of life (Q-LES-Q), social and occupational functioning (SOFAS), and functional impairment (LIFE–RIFT). Participants were asked to assess their symptom improvement with the PGI-I. Bland-Altman agreement plots and Intra-class correlations were used to evaluate agreement, and Spearman correlation coefficients were implemented to examine convergent validity. Sub-group analyses for disorder type (bipolar and major depression) were performed.

Results:

There was high agreement between the PGI-I and CGI-I ratings across follow-up time points (weeks 2, 4, 6, 8, 12, 16, 20, 24, and 28). Similar results were observed in male only and female only data and after adjustment for age and gender. Both PGI-I and CGI-I ratings were robustly positively correlated with MADRS, and LIFE-RIFT and negatively correlated with SOFAS and Q-LES-Q, supporting the convergent validity of the PGI-I. Sub-group analyses for bipolar and major depressive disorder showed similar findings.

Conclusion:

Our findings support the utility of the PGI-I as a participant rated measure of global improvement among individuals with bipolar or major depressive disorders.

Analysis of correlation between estradiol and fracture of femur neck

Osteoporosis is a major public health challenge all over the world. Estrogen hormone was cited amongst other hormones to be an efficient hormone for the production and maintenance of bone density. This study was designed with the purpose of evaluating and analyzing the estradiol effect on fractures of femur neck in the Iranian society. This study evaluated men over 50 years of age suffering with mild trauma (falling off the same level height or lower) and with a fracture on their femur neck. Also, their serum level of estradiol was measured with an ELISA method. Using this procedure, the patients were assigned into groups with either normal estradiol serum level (10pg/ml and higher) or with lower than normal level (lower than 10 pg/ml). A control group including 50-year-old and older men without hip fracture, or its history, was chosen to access their estradiol serum level. Data collected from these two groups were statistically compared. A total of 120 patients were evaluated (60 in the control and 60 in the test group). The mean age of patients in the control and test groups were 67.9±10.22 and 69.5±8.84 years, respectively (p=0.376). Smoker patients’ percentages in the control and test groups were 35% and 31.7%, respectively (p=0.699). On the basis of the serum estradiol level, patients’ percentages with low estradiol level in control and test groups were 10% and 16.7%, respectively (p=0.283). The only significant factor in predicting serum estradiol level was smoking. In conclusion, in this study it was observed that fractures of the femoral neck following a mild trauma were not correlated to low level of serum estradiol.

Trial protocol: a clustered, randomised, longitudinal, type 2 translational trial of alcohol consumption and alcohol-related harm among adolescents in Australia

Background

This cluster randomised control trial is designed to evaluate whether the Communities That Care intervention (CTC) is effective in reducing the proportion of secondary school age adolescents who use alcohol before the Australian legal purchasing age of 18 years. Secondary outcomes are other substance use and antisocial behaviours. Long term economic benefits of reduced alcohol use by adolescents for the community will also be assessed.

Methods

Fourteen communities and 14 other non-contiguous communities will be matched on socioeconomic status (SES), location, and size. One of each pair will be randomly allocated to the intervention in three Australian states (Victoria, Queensland and Western Australia). A longitudinal survey will recruit grade 8 and 10 students (M = 15 years old, N = 3500) in 2017 and conduct follow-up surveys in 2019 and 2021 (M = 19 years old). Municipal youth populations will also be monitored for trends in alcohol-harms using hospital and police administrative data.

Discussion

Community-led interventions that systematically and strategically implement evidence-based programs have been shown to be effective in producing population-level behaviour change, including reduced alcohol and drug use. We expect that the study will be associated with significant effects on alcohol use amongst adolescents because interventions adopted within communities will be based on evidence-based practices and target specific problems identified from surveys conducted within each community.

Trial registration

The trial was retrospectively registered in September, 2017 (ACTRN12616001276448), as communities were selected prior to trial registration; however, participants were recruited after registration. Findings will be disseminated in peer-review journals and community fora.

Prediction of major osteoporotic and hip fractures in Australian men using FRAX scores adjusted with trabecular bone score

There was no significant difference between the areas under receiver operating characteristics (AUROCs) and diagnostic indexes (sensitivity, specificity, positive predictive value, negative predictive value) for either major osteoporotic or hip fracture FRAX scores when comparing the unadjusted and trabecular bone score (TBS)-adjusted scores.

INTRODUCTION

FRAX 10-year probability of fracture can be calculated with adjustment for the TBS. Studies have shown that TBS can improve FRAX assessments in some populations. This study aimed to determine if TBS-adjusted FRAX score is better than the unadjusted score for predicting major osteoporotic fracture (MOF) and hip fracture in Australian men.

METHODS

This study involved 591 men aged 40-90 years, enrolled in the Geelong Osteoporosis Study. Incident MOF (n = 50) and hip fractures (n = 14) were ascertained using radiological reports. Median follow-up time was 9.5 years (IQR7.5-11.4). Diagnostic indexes were calculated using cut points of ≥20% for MOF and ≥3% for the hip. AUROC curves were also determined for adjusted and unadjusted scores as continuous variables.

RESULTS

Sensitivity was higher in the TBS-adjusted scores (MOF 4%, hip 78.6%) than the unadjusted scores (MOF 2%, hip 57.1%), with a decrease in specificity (MOF 98.9 vs 99.3%; hip 79.9 vs 83.9%). When considering TBS-adjusted and unadjusted FRAX as continuous scores, AUROCs were 0.738 and 0.740, respectively, for MOF and 0.849 and 0.848 for the hip.

CONCLUSIONS

Prediction of fractures by MOF or hip FRAX was not substantially improved by TBS adjustment. There was no difference in AUROCs or diagnostic indexes for cut-off points of ≥20 for MOF and ≥3% for hip FRAX.

The relationship between serum levels of fibroblast growth factor 21 and diabetic retinopathy

Fibroblast growth factor 21 (FGF21) is a major metabolic regulator that has been shown to be elevated in a number of metabolic disturbances including type 2 diabetes mellitus (T2DM) and the metabolic syndrome, but few studies about the relationship between serum FGF21 and the complications of diabetes have been done. Since the association between FGF21 and diabetic retinopathy is not clear, this study was conducted to investigate this relationship. In this cross-sectional study, 61 subjects (14 healthy controls, 22 diabetic patients without retinopathy, and 25 patients with diabetic retinopathy) were evaluated. All patients in the study were examined for the presence of diabetic retinopathy. Various clinical and biochemical parameters including FGF21 were evaluated and analyzed and compared between the study groups. Serum levels of FGF21 showed a significant difference between the three groups (P=0.003) but the difference between diabetic patients with and without retinopathy was not significant (P=0.122). Regression model was used to evaluate the role of FGF21 in predicting diabetic retinopathy. In the multivariate logistic regression model after adjustment of systolic blood pressure and fasting blood glucose, the level of FGF21 was not associated with diabetic retinopathy. In the multivariate model, only fasting blood glucose was associated with diabetic retinopathy (P=0.009). According to the results of this study, serum levels of FGF21 in diabetic patients was higher than the control group but these raised levels could not predict the presence of diabetic retinopathy.

Prevalence of arthritis according to age, sex and socioeconomic status in six low and middle income countries: analysis of data from the World Health Organization study on global AGEing and adult health (SAGE) Wave 1

Background

In higher income countries, social disadvantage is associated with higher arthritis prevalence; however, less is known about arthritis prevalence or determinants in low to middle income countries (LMICs). We assessed arthritis prevalence by age and sex, and marital status and occupation, as two key parameters of socioeconomic position (SEP), using data from the World Health Organization Study on global AGEing and adult health (SAGE).

Methods

SAGE Wave 1 (2007–10) includes nationally-representative samples of older adults (≥50 yrs), plus smaller samples of adults aged 18-49 yrs., from China, Ghana, India, Mexico, Russia and South Africa (n = 44,747). Arthritis was defined by self-reported healthcare professional diagnosis, and a symptom-based algorithm. Marital status and education were self-reported. Arthritis prevalence data were extracted for each country by 10-year age strata, sex and SEP. Country-specific survey weightings were applied and weighted prevalences calculated.

Results

Self-reported (lifetime) diagnosed arthritis was reported by 5003 women and 2664 men (19.9% and 14.1%, respectively), whilst 1220 women and 594 men had current symptom-based arthritis (4.8% and 3.1%, respectively). For men, standardised arthritis rates were approximately two- to three-fold greater than for women. The highest rates were observed in Russia: 38% (95% CI 36%–39%) for men, and 17% (95% CI 14%–20%) for women. For both sexes and in all LMICs, arthritis was more prevalent among those with least education, and in separated/divorced/widowed women.

Conclusions

High arthritis prevalence in LMICs is concerning and may worsen poverty by impacting the ability to work and fulfil community roles. These findings have implications for national efforts to prioritise arthritis prevention and management, and improve healthcare access in LMICs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1624-z) contains supplementary material, which is available to authorized users.

Minimally invasive radioguided parathyroid surgery using low-dose Tc-99m-MIBI - comparison with standard high dose

INTRODUCTION

Surgery remains the most effective treatment for primary hyperparathyroidism (PHPT). Minimally invasive radioguided parathyroidectomy (MIRP) is a common technique for detecting and excising abnormal parathyroid glands. The aim of this study was to compare injections of low-dose and high-dose (99m) Tc methoxy isobutyl isonitrile (MIBI) for intraoperative localisation of parathyroid adenomas by means of a gamma probe in patients with primary hyperparathyroidism (PHPT).

MATERIAL AND METHODS

Thirty patients with PHPT and a preoperative diagnosis of parathyroid adenoma were enrolled between 2010 and 2012. They were considered as Group B and underwent MIRP using 5 mCi Tc-99m MIBI, and their perioperative data were compared with twenty patients treated with conventional 20 mCi Tc-99m MIBI previously (Group A).

RESULTS

Group A was made up of 20 patients (mean age, 41.55 years; 14 women and 6 men), and group B included 30 patients (mean age, 40.43 years; 19 women and 11 men). The mean serum parathyroid hormone (PTH) and calcium values were recorded pre- and postoperatively. The mean follow-up period for the patients in the two groups was 18.4 and 16.5 months, respectively. Pre-operative evaluation demonstrated that the groups were statistically similar. Intraoperative data and success rate of surgery showed no difference between the two groups. No significant complication was detected after surgeries and no recurrence happened in either of the two groups during the follow-up period.

CONCLUSIONS

A new protocol of MIRP using low doses of Tc-99m-MIBI resulted in an excellent success rate. Comparing results of the study, we conclude that low-dose Tc-99m-MIBI may be preferred for identification of parathyroid adenomas intraoperatively by means of a gamma probe in PHPT patients because it appears to be as effective as high-dose Tc-99m-MIBI.

Effectiveness of stress and burnout management training for employees of an industrial company

Introduction

Burnout is a state of physical and emotional exhaustion. It can occur when people experience long-term stress in job, or when they have worked in a physically or emotionally draining role for a long time. There have been numerous studies done showing the results of stress and burnout in the employee's profession across many areas of health care.

Objectives

The purpose of this study was to investigate the effectiveness of stress and burnout management training on employees using experimental method to help employees to understand available resources and help them find better ways to manage stress in the workplace.

Aims

This study aims to discusses how organizations can assist in combating stress in ways that benefit both the employees involved and the organization itself.

Method

A curriculum-based intervention was developed to provide education in a classroom setting. The sample included 14 nurses with various nursing backgrounds who were selected randomly and were assigned randomly in two experimental and control groups, which contained 7 employees in each group. The experimental group received the training while the control group was in waiting list. The instruments were the General Health Questionnaire and Burnout Checklist, and demographic questionnaire. Data was analyzed by covariance analysis method.

Results

Result indicated that stress and burnout management training was efficient on reducing stress and burnout symptoms in employee.

Conclusion

It is concluded that stress and burnout management training is an effective group intervening method for reducing the dysfunctional effects of stress and job burnout in employees.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Academic Stress and Emotion Regulation in the Iranian Female Students with High and Low Academic Performance

Introduction

This paper examines the similarities and differences between academic stress and emotion regulation and investigates that the association between emotion regulation and academic stress may be explained the level of academic success among female students.

Objectives

This research suggests that students vary in their ability to regulate emotions and cope with academic stress, and these abilities may differ across the level of student's academic success. Identifying the academic stress and quality of emotion regulation strategies will lead to practical implications for promoting student's with low or high academic success.

Aims

The present study aims to compare academic stress and emotion regulation in the female students with high and low academic performance.

Methods

A total of 162 high school students (mean age = 15.26) were selected by cluster random sampling method. They were categorized as students with high (87 students) and low (75 students) academic performance by average of their academic performance. Emotion regulation questionnaire, educational stress scale for adolescents and academic performance were administered. One-way MANOVA was conducted on academic stress and emotion regulation.

Results

The results of analysis were significant only for emotion regulation, F (5, 156) = 5.34, P = .001. Mean score of students with low academic performance in the emotion regulation was significantly lower than students with high academic performance.

Conclusions

The extent to which variation in emotion regulation and coping with stress can be considered as a key factor of academic failure/success in educational settings.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Strong electric field enhancements in asymmetric metallic nanostructures and high-order harmonic generation

Numerical investigation of high-order harmonic generation (HHG) is carried out in noble gases near metal nano-dimers. The effect of geometry, shape, and gap of the dimers in plasmon resonance and local electric field enhancement has been investigated numerically by using finite-difference time-domain methods. It is shown that a lack of symmetry in dimer shapes plays an important role in the HHG process, producing appreciable modifications to the energy-resolved photoelectron spectra.

Extension of high-order harmonic generation cutoff via control of chirped laser pulses in the vicinity of metal nanostructure media

By using a suitable chirping field, an ultrashort pulse was obtained in the vicinity of the metal nanostructure.

Oral bioavailability and pharmacokinetic study of cetrizine HCl in Iranian healthy volunteers

The objective of the present study was to evaluate the pharmacokinetic parameters and bioavailability of a selective histamine (H1)-receptor antagonist, cetirizine hydrochloride (CTZ), following administration of a single oral dose of the drug. The properties of a test compound were compared with those of a reference product in a randomized cross-over study in 12 volunteers. Blood samples were collected at selected time intervals up to 24 h and plasma concentrations of CTZ were determined using a validated HPLC method. Pharmacokinetic parameters including T(1/2), T(1/2)(abs), K, K(a), T(max), C(max), V(d)/F, Cl/F, AUC(0-24), AUC (0-∞) and MRT were determined from plasma concentration-time profiles for tested products and found to be in good agreement with previous reports. The analysis of variance did not show any significant differences between the test and reference products. The confidence intervals for the ratio of C(max) (95-110%), AUC(0-24) (91-112%) and AUC(0-∞) (92-109%) for the test and reference products were within the acceptable interval of 80-125%. ANOVA assessment of logarithmically transformed data did not reveal any significant subject, period or sequence effects. It was, therefore, concluded that the two products were bioequivalent and could be used interchangeably.

Single-mode mid-IR guidance in a hollow-core photonic crystal fiber

We report, for the first time, bandgap guidance above 3 mum in a silica based air-core photonic crystal fiber. The peak of the bandgap is at 3.14mum with a typical attenuation of ~ 2.6 dB m-1. By further optimization of the structure, modeling suggests that a loss below 1 dB m-1 should be achievable, greatly extending the useful operating range of silica-based single-mode fibers. Such fibers have many potential applications in the mid-IR, offering an alternative to fluoride, tellurite or chalcogenide glass based optical fibers for chemical and biological sensing applications.