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1.
J Pak Med Assoc ; 74(1 (Supple-2)): S2-S7, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38385463

ABSTRACT

OBJECTIVE: To compare the serum levels of biochemical and oxidative stress markers i.e., malondialdehyde (MDA) and paraoxonase-1(PON1) in polycystic ovary syndrome (PCOS) patients and healthy female individuals of reproductive age group (18-40 years). METHODS: This case-control study was conducted in Dow University of Health Sciences (DUHS), Karachi from June 2019 to October 2020. Seventy Subjects including 35 PCOS patients that have primary subfertility problem (cases) and 35 healthy and fertile females (controls) were recruited. Serum samples were collected for analysis of insulin, sex hormone-binding globulin, testosterone, fasting blood glucose and lipid profile. PON 1 and MDA levels were estimated by ELISA. Comparison between the two groups was done using independent t-test. RESULTS: The patients had significantly increased mean body mass index (28.5+4.6 kg/m2 vs 25.7+4.5 kg/m2, p=0.014), systolic (129.6±13.9 mm of Hg vs 113±7.7 mm of Hg, p<0.001) and diastolic (78.7±8.8 mm of Hg vs 74.6±6.7 mm of Hg, p=0.032) blood pressures compared to controls. The high-density lipoprotein cholesterol levels were significantly lower in PCOS (42.2±8.6mg/dl) than controls (48.8±11.8mg/dl, p=0.009, p=0.009). Serum insulin (14.3±5.8 uIU/mL) vs (10.0±5.2 uIU/mL), p=0.002 and testosterone levels (1.3±0.9 nmol/L) vs (0.82±0.3 nmol/L), p<0.001 were significantly higher whereas sex hormone binding globulin (SHBG) levels (35.2±19.7nmol/L vs 58.8±31.0 nmol/L) were significantly lower in patients than healthy controls (p<0.001). Both oxidative stress markers, paraoxonase 1 (7.7±2.4 vs 6.4±2.6 µg/mL, p=0.04) and malondialdehyde (2.5±1.0 vs 1.9+0.51µg/mL, p=0.034) levels were significantly elevated in PCOS patients than controls. No significant correlation was found between dietary habits and life style between cases and controls. CONCLUSIONS: The study reported significantly elevated levels of oxidative stress markers in PCOS patients.


Subject(s)
Insulin Resistance , Mercury , Polycystic Ovary Syndrome , Female , Humans , Adolescent , Young Adult , Adult , Case-Control Studies , Insulin , Testosterone , Oxidative Stress , Malondialdehyde , Aryldialkylphosphatase
2.
J Pak Med Assoc ; 74(1 (Supple-2)): S47-S50, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38385471

ABSTRACT

Objectives: To determine the levels of zinc in hair and serum samples of chronic telogen effluvium patients. METHODS: The case-control study was conducted at the Dow University of Health Sciences, Karachi, from April 2017 to May 2018, and comprised diagnosed cases of chronic telogen effluvium in group A, and healthy controls matched for age and gender in group B. Hair pull test was done, and level of zinc in hair and serum samples was determined using atomic absorption spectrophotometer. Data was analysed using SPSS 21. RESULTS: Of the 100 subjects, 50(50%) were in group A; 28(56%) females ad 22(44%) males with mean age 27.46±4.98 years. There were 50(50%) subejcts in group B; 26(52%) males ad 24(48%) females with mean age 28.34±4.92 years (p>0.05). Significantly low levels of zinc were observed in serum as well as hair samples in group A compared to group B (p<0.05). A positive significant association was observed in the level of zinc in hair with their concentration in the serum of subjects in both the groups (r=0.310, p<0.05). CONCLUSIONS: Low levels of zinc in hair and serum were found to be associated with chronic telogen effluvium.


Subject(s)
Alopecia Areata , Zinc , Male , Female , Humans , Young Adult , Adult , Case-Control Studies , Alopecia/complications , Alopecia/diagnosis , Hair
3.
J Pak Med Assoc ; 74(1 (Supple-2)): S29-S32, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38385468

ABSTRACT

Objectives: To compare leptin levels in newly-diagnosed treatment-naive epileptic patients and healthy controls. METHODS: This case-control study was conducted from January 10 to September 15, 2022, at the Dow University of Health Sciences, Karachi, and comprised newly-diagnosed epileptic patients age 12-35years who had no comorbidity. The subjects were enrolled from the Neurology out-patient department of Civil Hospital, Karachi. Healthy individuals matched for age, gender and body mass index were also enrolled as controls. Blood samples were collected between 8am and 10am for the evaluation of serum leptin levels using enzyme-linked immunosorbent assay. Data was analysed using SPSS 26. RESULTS: Of the 100 subjects, 64(64%) were males and 36(36%) were females. There were 50(50%) cases with mean age 19.34±5.65 years, and 50(50%) controls with mean age 19.76±5.67 (p=0.614). 100% of 50 individuals in control group did not have any family history of epilepsy,while 18% of cases (9) reported a positive family history. Mean leptin level in cases was 31.03±19.37 compared to 5.25±4.03 in the controls (p<0.05). CONCLUSIONS: Serum leptin levels were elevated in newly-diagnosed epileptic patients compared to healthy controls.


Subject(s)
Epilepsy , Leptin , Adolescent , Adult , Child , Female , Humans , Male , Young Adult , Body Mass Index , Case-Control Studies , Epilepsy/diagnosis , Leptin/blood
4.
J Pak Med Assoc ; 74(1 (Supple-2)): S8-S13, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38385464

ABSTRACT

OBJECTIVE: To assess the link between tumour necrosis factor-alpha -308 guanine/adenine polymorphism and tumour necrosis factor-alpha plasma levels in relation to obstructive sleep apnoea. METHODS: The cross-sectional study was conducted from December 2018 to March 2021 at the sleep clinic of Dow University Hospital, Karachi, on obstructive sleep apnoea patients and healthy controls. Epworth Sleep Scale score was used to determine daytime sleepiness, while full-night polysomnography was carried out for obstructive sleep apnoea confirmation and categorisation according to severity. Blood sample collection was followed by deoxyribonucleic acid extraction and plasma tumour necrosis factor-alpha measurement using enzyme-linked immunosorbent assay. Genotype distribution and allelic frequency were assessed. Data was analysed using SPSS 20. RESULTS: Out of the 225 subjects, with a mean age of 47.68±9.88 years, 132 (58.7%) were males, and 93 (41.3%) were females. Among them, 150 (66.7%) were patients, and 75 (33.3%) were controls. Heterozygous tumour necrosis factor-alpha -308 guanine/adenine genotypes were significantly higher among the patients (p<0.05). Minor allele - 308 adenine showed an association with obstructive sleep apnoea, its severity, higher tumour necrosis factor-alpha levels, neck circumference, excessive daytime sleepiness and the presence of hypertension (p<0.05). CONCLUSIONS: Tumour necrosis factor-alpha -308 adenine allele and higher tumour necrosis factor-alpha levels were found to be linked with obstructive sleep apnoea. The polymorphism also showed an association with hypertension in obstructive sleep apnoea patients.


Subject(s)
Disorders of Excessive Somnolence , Hypertension , Sleep Apnea, Obstructive , Tumor Necrosis Factor-alpha , Adult , Female , Humans , Male , Middle Aged , Adenine , Cross-Sectional Studies , Disorders of Excessive Somnolence/complications , Guanine , Hypertension/complications , Pakistan/epidemiology , Sleep Apnea, Obstructive/epidemiology , Sleep Apnea, Obstructive/genetics , Sleep Apnea, Obstructive/complications , Tumor Necrosis Factor-alpha/genetics
6.
J Pak Med Assoc ; 73(6): 1349-1352, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37427652

ABSTRACT

Institute of Biomedical Sciences (IBMS) at Dow University of Health Sciences (DUHS), organised a two day's conference on Biomedical Sciences. IBMS being the part of one of the largest public sector health universities of Pakistan, is now transforming the research trends to be effectively translated at the community level. Currently with a strong PhD faculty line in basic and clinical sciences, DUHS has a significant contribution in research output of the country. The scientific data however represents a small population per scientific study and the generalization of results may not be inferred. It must be extended through translational research for effectiveness. The conference was planned with a theme to bridge the gap between basic and translational research. The two day's conference conducted in second week of March 2023 at Dow International Medical College Ojha Campus DUHS was able to attract more than 300 participants. The scientific sessions encompassed a vast variety of health issues and their proposed solutions including neurosciences, virtual biopsies, metabolomics, medical writings and incorporation of engineering and artificial intelligence to facilitate detection and prognosis of disease. The conference was able to conclude that the multidisciplinary research studies with collaboration of two or more institutes/organizations are the need of time. Young researchers need an effective platform to showcase their research and make collaborations. Moreover, the incorporation of artificial intelligence would enhance patient care within health systems.


Subject(s)
Artificial Intelligence , Biomedical Research , Humans , Pakistan , Faculty , Academies and Institutes , Metabolomics
7.
J Pak Med Assoc ; 72(7): 1350-1354, 2022 Jul.
Article in English | MEDLINE | ID: mdl-36156559

ABSTRACT

OBJECTIVE: To assess the relationship of tumour necrosis factor-alpha with obstructive sleep apnoea and its severity in Pakistani population. METHODS: The cross-sectional study was conducted at the Sleep Laboratory of Dow University Hospital, Karachi, from December, 2018, to March, 2020, and comprised patients of either gender having symptoms of snoring, witnessed apnoea or daytime sleepiness. They were divided into four groups on the basis of obstructive sleep apnoea status. Those without obstructive sleep apnoea were in Group A, mild status in Group B, moderate in Group C and severe obstructive sleep apnoea in Group D. Polysomnography was done to confirm obstructive sleep apnoea status and to categorise the subjects using apnoea-hypopnoea index, while enzyme-linked immunosorbent assay was used to assess their tumour necrosis factor alpha levels.. Data was analysed using SPSS 20. RESULTS: Of the 150 subjects, 94(63%) were males. The overall mean age was 49.68±12.14 years. There were 50(33.33%) subjects in Group A, 19(12.66%) Group B, 23(15.33%) Group C and 58(38.66%) in Group D. Mean tumour necrosis factor-alpha level was 3.88±1.65pg/mL in Group A, 9.97±4.33 pg/mL in Group B, 12.65±4.46 pg/mL in Group C and 12.83±4.33 pg/mL in Group D. Mean tumour necrosis factor-alpha levels had significant association with the severity of obstructive sleep apnoea (p<0.001). CONCLUSIONS: Higher levels of tumour necrosis factor-alpha were found to be associated with obstructive sleep apnoea, and can be considered a potential biomarker for early diagnosis.


Subject(s)
Sleep Apnea, Obstructive , Tumor Necrosis Factor-alpha , Adult , Biomarkers , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Sleep Apnea, Obstructive/complications , Sleep Apnea, Obstructive/diagnosis , Sleep Apnea, Obstructive/epidemiology , Snoring/complications
8.
Antibiotics (Basel) ; 10(11)2021 Nov 15.
Article in English | MEDLINE | ID: mdl-34827338

ABSTRACT

Treating periodontitis with metronidazole (MET) as an adjunct to scaling root planing (SRP) is suggested to have inconsistent effects on insulin resistance (IR) in type 2 diabetes mellitus (T2DM). This paper will present the effects of MET, in addition to SRP, on the homeostatis model assessment of IR (HOMA-IR). A three-arm clinical trial was conducted and analyses were performed on T2DM participants with periodontitis (n = 74) who completed follow-up visits at 3 and 6 months after the intervention. The observed between-group and within-group mean changes in IR were found using ANOVA with repeated measures, followed by a post-hoc analysis, and a p-value of ≤0.05 was considered significant. Between-group analyses showed no difference in the HOMA-IR at 3 months, but at 6 months the difference was significant (p = 0.046). Within-group analyses showed that the HOMA-IR was significantly reduced in both test groups (p ≤ 0.05) over the period of time. Adjunct use of MET may result in a sudden short-term lowering of the HOMA-IR level within 3 months that may not be retained over 6 months when compared to the sustained lowering of the HOMA-IR levels in T2DM when intervened with SRP without MET.

9.
BMC Oral Health ; 21(1): 253, 2021 05 12.
Article in English | MEDLINE | ID: mdl-33980234

ABSTRACT

BACKGROUND: Treating periodontitis through non-surgical periodontal therapy (NSPT) may improve glycemic control in type-2 Diabetes Mellitus (T2DM) patients. However, the evidence to maintain this improvement beyond four months is insufficient. Hence, this trial was conducted to assess clinical efficacy of NSPT on glycemic control in T2DM patients. METHODS: This three-arm randomized controlled trial recruited 150 known T2DM participants (35-65 years), suffering from moderate to severe periodontitis, having HbA1c level ≥ 6.5% at baseline. Participants were followed up at 3 and 6 months. Intervention for test group-1 included scaling and root planing (SRP) with metronidazole (MET) and oral hygiene instructions (OHI). Test group-2 was intervened with SRP + OHI and control group with OHI only. Stata v. 14 was used to observe inter and intragroup mean changes in glycemic [glycated hemoglobin (HbA1c), fasting blood glucose (FBG)] and periodontal variables [bleeding on probing (BOP), periodontal pocket depth (PPD), clinical attachment loss (CAL)] using ANOVA and RMANOVA. Proportion of change in outcome variable (HbA1c) was assessed between treatment groups using chi-square test. Change was considered significant at p-value ≤ 0.05. RESULTS: A significant reduction was observed in BOP, PPD, CAL, HbA1c and FBG over time [p < 0.05]. Significant reductions were observed in same variables in both test groups in comparison to control arm [p < 0.05]. No change between the two test groups was observed [p > 0.05]. CONCLUSION: Scaling and root planing improves glycemic control of T2DM patients independently of the use of MET. Therefore, SRP after every 6 months may be suggested and included as a part of overall diabetes management for patients suffering from T2DM. Clinical trial registration NCT 03,343,366 [Date of Registration: 17/11/2017].


Subject(s)
Chronic Periodontitis , Metronidazole , Blood Glucose , Chronic Periodontitis/drug therapy , Dental Scaling , Humans , Metronidazole/therapeutic use , Periodontal Attachment Loss , Root Planing , Treatment Outcome
10.
J Clin Transl Hepatol ; 9(1): 15-21, 2021 Feb 28.
Article in English | MEDLINE | ID: mdl-33604251

ABSTRACT

BACKGROUND AND AIMS: Multiple non-invasive methods including radiological, anthropometric and biochemical markers have been reported with variable performance. The present study assessed glycosylated hemoglobin (HbA1C) as a biomarker to predict non-alcoholic fatty liver disease (NAFLD) and its severity, compared with body mass index (BMI), waist to hip ratio (WHR) and waist circumference (WC). METHODS: This case control study included 450 individuals, including 150 cases and 300 age- and gender-matched controls recruited from the Dow Radiology Institute on the basis of radiological findings of fatty infiltration on abdominal ultrasound through convenient sampling. BMI, WHR and WC were measured according to standard protocols. HbA1C was determined by turbidimetric inhibition immunoassay. RESULTS: Among the cases and controls, 66% and 32% had HbA1C levels higher than 5.7% respectively. HbA1C and BMI were significantly associated with NAFLD [crude odds ratio (cOR)=4.12, 2.88, 2.25 (overweight) and 4.32 (obese)]. WC was found to be significantly associated with NAFLD for both genders (cOR in males=5.50 and females=5.79, p<0.01). After adjustment for other parameters, HbA1C and WC were found to be significantly associated with NAFLD (aOR=3.40, p<0.001) along with WC in males (aOR=2.91, p<0.05) and in females (aOR=4.28, p<0.05). A significant rise in severity of hepatic steatosis was noted with increases in HbA1C, BMI and WC. HbA1C possessed a positive predictive value of 76% for the study population [0.76, confidence interval (CI): 0.715-0.809], 70.6% for males (0.706, CI: 0.629-0.783) and 80% for females (0.80, CI: 0.741-0.858). CONCLUSIONS: Higher than normal HbA1C and WC measurements possess a more than 70% potential to predict NAFLD. It is the single risk factor that is strongly associated with NAFLD after adjustment for indices of body measurements. HbA1C may be presented as a potential biomarker for NAFLD in examination with other anthropometric measures in the adult population.

11.
Arch Med Res ; 52(3): 348-353, 2021 04.
Article in English | MEDLINE | ID: mdl-33187731

ABSTRACT

BACKGROUND: Being the primary target of antipsychotic therapy, dopamine receptor type 2 (DRD2) remains a point of interest in schizophrenia pathology. Polymorphisms in DRD2 have been shown to alter patients' response to antipsychotics. DRD2 SNP rs6275 (C>T) have found to be associated with schizophrenia in different populations; however, data remains inconsistent. AIM OF THE STUDY: Keeping in view the genetic diversity the present study was aimed to explore association of rs6275 with schizophrenia in population from Pakistan. METHOD: Using Diagnostic and statistical Manual 5 (DSM 5) criteria, 100 schizophrenia cases and 100 controls (individuals without any psychiatric illness) were enrolled in the study. Severity of illness was determined using PANSS score. Genotyping was done via Sanger sequencing. MEGA-X was used to align the sequences, Expasy translate tool was used to translate nucleotide sequences. Difference in genotype and allele frequencies between cases and controls was determined using χ2 test. RESULT: No significant difference in genotype or allele frequencies of rs6275 (p >0.0.5) was found between cases and controls. Interestingly, a novel SNP (C>A, Pro297Thr) was spotted during electropherogram analysis at position chr11:113412805. Significant difference was found in genotype and allele frequency of this novel SNP among schizophrenia cases and controls (p = 0.003). CONCLUSION: No association of rs6275 was observed with schizophrenia in Pakistani population. However, the study found significant association of a novel missense SNP of DRD2 at chr11:113412805 (C>T) with schizophrenia in Pakistani population. A large-scale multicenter study will be required to confirm the association of this novel SNP with schizophrenia.


Subject(s)
Receptors, Dopamine D2/genetics , Schizophrenia/genetics , Adult , Case-Control Studies , Female , Humans , Male , Polymorphism, Genetic
12.
J Pak Med Assoc ; 70(8): 1350-1356, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32794485

ABSTRACT

OBJECTIVE: To assess a relationship and predict changes in glycaemic control due to chronic periodontitis in type-2 diabetic patients. METHODS: Chronic periodontitis (CP) of a cross-section of 118 patients (age ?32 years) was determined using bleeding on probing (BOP), periodontal pocket depth (PPD) and clinical attachment loss (CAL). Their HbA1c, fasting blood glucose (FBG), fasting serum insulin (FSI) and homeostasis assessment model of insulin resistance (HOMA-IR) levels were also tested. Stata 11.0 was used to assess correlation between periodontal and glycaemic measures. Univariate analysis followed by multiple regression analysis through stepwise forward selection process was used to explore significant variables that may predict change in HbA1c. Multi-collinearity and heteroskedasticity were assessed at p-value > 0.05. RESULTS: Results of participants (n=95) showed significantly positive correlations (r) between HbA1c and BOP [r = 0.34, p-value = 0.002], PPD [r = 0.36, p-value = 0.003] and CAL [r=0.42, p-value = 0.002]. However, FBG and HOMA-IR were not found correlated with any of the periodontal measures; except CAL with FBG [r=0.27, p-value=0.02]. In addition to healthy controlled diet, cultural background, education and FBG, CAL was found significant [coef. = 0.746, p-value = 0.001, CI = 0.339, 1.153] to predict change in HbA1c in the final model [R2 = 0.549, p-value < 0.001] with no multicollinearity [mean VIF =1.30] and heteroskedasticity [chi 2 =0.02, p-value= 0.878] in fi n al model. CONCLUSIONS: Increased CAL is estimated to increase HbA1c level by 0.75% in T2DM patients after controlling other factors. It is suggested that periodontal prophylactic management may be planned with an aim to reduce HbA1c. CLINICAL TRIAL REGISTRATION NO: NCT03343366.


Subject(s)
Diabetes Mellitus, Type 2 , Insulin Resistance , Periodontitis , Adult , Blood Glucose , Diabetes Mellitus, Type 2/complications , Glycated Hemoglobin/analysis , Humans
13.
Arch Med Res ; 51(6): 548-555, 2020 08.
Article in English | MEDLINE | ID: mdl-32505416

ABSTRACT

BACKGROUND: Arginine vasopressin (AVP) plays an important role in the pathophysiology of Diabetes Mellitus (DM) and its related complications like diabetic nephropathy. Copeptin is considered as a reliable surrogate biomarker of AVP. If raised levels of copeptin in diabetic patients are detected earlier, prognosis of DM can be improved by timely modulating the treatment strategy. AIMS OF THE STUDY: The study is therefore planned to assess copeptin levels in different groups of DM and in healthy controls to suggest a better and reliable biomarker for progressive stages of DM. METHODS: Subjects were recruited as controls, pre diabetes, DM without nephropathy and diabetic nephropathy. Serum copeptin levels were measured by ELISA. While, Blood Urea Nitrogen (BUN), creatinine, Glycosylated Hemoglobin (HbA1c) and spot urinary albumin creatinine ratio (UACR) were done using spectrophotometry. Statistical analysis was done using ANOVA and Pearson's correlation tests on SPSS. RESULTS: The average copeptin levels were 215.096 pg/mL. Copeptin levels were significantly elevated in subjects with positive family history of DM (p = 0.025), levels were also raised in pre diabetes kpatients (252.85 pg/mL) as compared to other groups. Copeptin levels were also correlated with HbA1c r = 0.171 (p = 0.101), BUN r = 0.244 (p = 0.007), creatinine r = 0.215 (p = 0.018), UACR r = 0.375 (p = <0.001) and GFR r = 0.215 (p = <0.019). CONCLUSION: The significant correlation of copeptin with diabetic and renal biomarkers, along with its positive association with family history of DM support its' role as an early and reliable biomarker of DM and its associated nephropathy.


Subject(s)
Biomarkers/blood , Diabetes Mellitus, Type 2/blood , Diabetic Nephropathies/blood , Glycopeptides/adverse effects , Kidney Function Tests/methods , Kidney/pathology , Neurophysins/metabolism , Protein Precursors/metabolism , Vasopressins/metabolism , Adolescent , Adult , Aged , Female , Glycopeptides/blood , Humans , Male , Middle Aged , Prognosis , Young Adult
14.
Community Ment Health J ; 55(5): 854, 2019 Jul.
Article in English | MEDLINE | ID: mdl-30238281

ABSTRACT

The original version of this article unfortunately contained a typo in the author name. The co-author name should be Ahsan Ehtesham instead it was published as Ahsan Ehtisham.

15.
Community Ment Health J ; 55(5): 849-853, 2019 07.
Article in English | MEDLINE | ID: mdl-30145668

ABSTRACT

The aim of the present was to assess and compare the mental health of male and female healthcare students in a Health University of Karachi, Pakistan. A cross-sectional study was conducted for which questionnaire was designed along the standard scoring scales of depression (PHQ-9), anxiety (GAD-7) and phobia (IAPT) completed by 300 enrolled students. Females (52%) of the medical institute suffered from mild to moderately-severe depression in contrast to the males (33%). Females were found to be affected by mild anxiety and phobia (42.7 and 26% respectively) exceeding the male population (27.3 and 15.3% respectively). However, severe depression or anxiety was not observed in either gender groups significantly, suggesting a healthy mental picture of these medical students. It can be concluded that health care students in modern upgraded education systems, in contrast to evidence from literature, have been able to adopt better coping mechanisms for maintaining their mental health.


Subject(s)
Mental Disorders/epidemiology , Students, Medical/psychology , Cross-Sectional Studies , Female , Health Surveys , Humans , Male , Pakistan/epidemiology , Prevalence , Sex Factors
16.
Inorg Chem ; 57(1): 37-44, 2018 Jan 02.
Article in English | MEDLINE | ID: mdl-29236485

ABSTRACT

Recently, we reported the synthesis and investigations of EuSr2Bi2S4F4 and Eu2SrBi2S4F4. We have now been able to induce superconductivity in EuSr2Bi2S4F4 by Se substitution at the S site (isovalent substitution) with Tc = 2.9 K in EuSr2Bi2S2Se2F4. The other compound, Eu2SrBi2S4F4, shows a significant enhancement of Tc. In Se-substituted Eu2SrBi2S4-xSexF4, we find Tc = 2.6 K for x = 1.5 and Tc = 2.8 K for x = 2, whereas Tc = 0.4 K in the Se-free sample. In addition to superconductivity, an important effect associated with Se substitution is that it gives rise to remarkable changes in the Eu valence. Our 151Eu Mössbauer and X-ray photoemission spectroscopic measurements show that Se substitution in both of the compounds Eu2SrBi2S4F4 and EuSr2Bi2S4F4 gives rise to an increase in the Eu2+ component in the mixed-valence state of Eu.

17.
Inorg Chem ; 56(6): 3182-3189, 2017 Mar 20.
Article in English | MEDLINE | ID: mdl-28245123

ABSTRACT

We have synthesized two new Eu-based compounds, EuSr2Bi2S4F4 and Eu2SrBi2S4F4, which are derivatives of Eu3Bi2S4F4, an intrinsic superconductor with Tc = 1.5 K. They belong to a tetragonal structure (SG: I4/mmm, Z = 2), similar to the parent compound Eu3Bi2S4F4. Our structural and 151Eu Mössbauer spectroscopy studies show that, in EuSr2Bi2S4F4, Eu-atoms exclusively occupy the crystallographic 2a-sites. In Eu2SrBi2S4F4, 2a-sites are fully occupied by Eu-atoms and the other half of Eu-atoms and Sr-atoms together fully occupy 4e-sites in a statistical distribution. In both compounds Eu atoms occupying the crystallographic 2a-sites are in a homogeneous mixed valent state ∼2.6-2.7. From our magnetization studies in an applied H ≤ 9 T, we infer that the valence of Eu-atoms in Eu2SrBi2S4F4 at the 2a-sites exhibits a shift toward 2+. Our XPS studies corroborate the occurrence of valence fluctuations of Eu and after Ar-ion sputtering show evidence of enhanced population of Eu2+-states. Resistivity measurements, down to 2 K, suggest a semimetallic nature for both compounds.

18.
Sci Rep ; 6: 37527, 2016 11 28.
Article in English | MEDLINE | ID: mdl-27892482

ABSTRACT

We have carried out detailed magnetic and transport studies of the new Sr0.5Ce0.5FBiS2-xSex (0.0 ≤ x ≤ 1.0) superconductors derived by doping Se in Sr0.5Ce0.5FBiS2. Se-doping produces several effects: it suppresses semiconducting-like behavior observed in the undoped Sr0.5Ce0.5FBiS2, the ferromagnetic ordering temperature, TFM, decreases considerably from 7.5 K (in Sr0.5Ce0.5FBiS2) to 3.5 K and the superconducting transition temperature, Tc, gets enhanced slightly to 2.9-3.3 K. Thus in these Se-doped materials, TFM is marginally higher than Tc. Magnetization studies provide evidence of bulk superconductivity in Sr0.5Ce0.5FBiS2-xSex at x ≥ 0.5 in contrast to the undoped Sr0.5Ce0.5FBiS2 (x = 0) where magnetization measurements indicate a small superconducting volume fraction. Quite remarkably, as compared with the effective paramagnetic Ce-moment (~2.2 µB), the ferromagnetically ordered Ce-moment in the superconducting state is rather small (~0.1 µB) suggesting itinerant ferromagnetism. To the best of our knowledge, Sr0.5Ce0.5FBiS2-x Sex (x = 0.5 and 1.0) are distinctive Ce-based bulk superconducting itinerant ferromagnetic materials with Tc < TFM. Furthermore, a novel feature of these materials is that they exhibit a dual and quite unusual hysteresis loop corresponding to both the ferromagnetism and the coexisting bulk superconductivity.

19.
Nat Mater ; 15(1): 32-7, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26524131

ABSTRACT

Three-dimensional (3D) Dirac semimetals exist close to topological phase boundaries which, in principle, should make it possible to drive them into exotic new phases, such as topological superconductivity, by breaking certain symmetries. A practical realization of this idea has, however, hitherto been lacking. Here we show that the mesoscopic point contacts between pure silver (Ag) and the 3D Dirac semimetal Cd3As2 (ref. ) exhibit unconventional superconductivity with a critical temperature (onset) greater than 6 K whereas neither Cd3As2 nor Ag are superconductors. A gap amplitude of 6.5 meV is measured spectroscopically in this phase that varies weakly with temperature and survives up to a remarkably high temperature of 13 K, indicating the presence of a robust normal-state pseudogap. The observations indicate the emergence of a new unconventional superconducting phase that exists in a quantum mechanically confined region under a point contact between a Dirac semimetal and a normal metal.

20.
Peptides ; 74: 1-8, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26456504

ABSTRACT

Leptin is viewed as an important target for developing novel therapeutics for obesity, depression/anxiety and cognitive dysfunctions. The present study therefore concerns behavioral, hormonal and central serotonin modulating effects of systemically injected leptin. Pharmacological doses (100 and 500 µg/kg) of leptin injected systemically decreased 24h cumulative food intake and body weight in freely feeding rats and improved acquisition and retention of memory in Morris water maze test. Potential anxiety reducing, hormonal and serotonin modulating effects of the peptide hormone were determined in a separate experiment. Animals injected with 100 or 500 µg/kg leptin were tested for anxiety in an elevated plus maze test 1h later. A significant increase in the number of entries and time passed in open arm of the elevated plus maze in leptin injected animals suggested pronounced anxiety reducing effect. Moreover, circulating levels of leptin correlated significantly with anxiety reducing effects of the peptide hormone. Serum serotonin increased and ghrelin decreased in leptin injected animals and correlated, positively and negatively respectively, with circulating leptin. Corticosterone increased at low dose and levels were normal at higher dose. Serotonin metabolism in the hypothalamus and hippocampus decreased only at higher dose of leptin. The results support a role of leptin in the treatment of obesity, anxiety and cognitive dysfunctions. It is suggested that hormonal and serotonin modulating effects of leptin can alter treatment efficacy in particularly comorbid conditions.


Subject(s)
Anxiety/drug therapy , Eating/drug effects , Leptin/administration & dosage , Memory/drug effects , Serotonin/blood , Animals , Anxiety/blood , Behavior, Animal/drug effects , Body Weight/drug effects , Ghrelin/blood , Hypothalamus/drug effects , Injections , Leptin/blood , Male , Rats , Rats, Wistar
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