A quantum ruler for orbital magnetism in moiré quantum matter.

For almost a century, magnetic oscillations have been a powerful "quantum ruler" for measuring Fermi surface topology. In this study, we used Landau-level spectroscopy to unravel the energy-resolved valley-contrasting orbital magnetism and large orbital magnetic susceptibility that contribute to the energies of Landau levels of twisted double-bilayer graphene. These orbital magnetism effects led to substantial deviations from the standard Onsager relation, which manifested as a breakdown in scaling of Landau-level orbits. These substantial magnetic responses emerged from the nontrivial quantum geometry of the electronic structure and the large length scale of the moiré lattice potential. Going beyond traditional measurements, Landau-level spectroscopy performed with a scanning tunneling microscope offers a complete quantum ruler that resolves the full energy dependence of orbital magnetic properties in moiré quantum matter.

RISK FACTORS FOR ACUTE KIDNEY INJURY ASSOCIATED WITH SEVERE HYPOTHYROIDISM.

Objective: This study aims to investigate the factors affecting development of acute kidney injury (AKI) in patients with severe hypothyroidism. Methods: This retrospective observational study involved patients with primary hypothyroidism and thyroid stimulating hormone (TSH) levels of more than 50 mIU/L at their review in the endocrinology outpatient clinic, between January 2015 and April 2021. Factors affecting the development of AKI were examined by logistic regression analysis. Results: A total of 100 patients, 20 (11 male (M), 9 female (F)) in the AKI (case) group and 80 (23 M, 57 F) patients in control group, were included in our study. The median age of the case group (56 years, interquartile range (IQR) 44.3-68.5) was significantly higher than the control group (49 years, IQR 32.3-60; p = 0.027), and the ratio of males to females was significantly higher in the case group (p = 0.001). Multivariate logistic regression analyses showed that hypothyroidism diagnosed after the age of 60 years (odds ratio (OR) 59.674, 95% confidence intervals (CI) 5.955-598.031; p = 0.001), free triiodothyronine (FT3) < 1.3 pg/mL (OR 17.151, 95% CI 2.491-118.089; p = 0.004) and creatine kinase (CK) > 1000 U/L (OR 1.522, 95% CI 1.602-82.848; p = 0.015) were predictors for the development of AKI in patients with severe hypothyroidism. Conclusion: We recommend close follow-up and monitoring of patients with AKI caused by severe hypothyroidism if patients who are diagnosed at age > 60 years, CK > 1000 U/L or FT3 < 1.3 pg/mL.

Excessive screen time and lower psychosocial well-being among preschool children.

OBJECTIVE: Too much screen time is a common and severe threat to child health and excessive screen exposure exists in the early childhood population in Turkey. We aimed to investigate the associations between excessive screen time and psychosocial well-being in a sample of Turkish preschool children. METHODS: Mothers and their healthy children aged 2-5 years who applied to general pediatric outpatient clinics for well-child examinations were enrolled in this descriptive cross-sectional study. Children with a daily screen time of less than 1 h (low) or more than or equal to 4 h (excessive) were included. Psychosocial well-being was assessed using the parent version of the Strengths and Difficulties Questionnaire. RESULTS: In all, 220 mother-child pairs participated in this study. Emotional symptoms, conduct problems, peer relationship problems, and total difficulties scores were significantly higher in the children with excessive screen time (p<0.05), while the hyperactivity-inattention and prosocial scores were not different between the low and excessive screen time groups (p>0.05). After adjusting for potential confounders, the children with excessive screen time had significantly increased odds ratios for having conduct and peer relationship problems (OR [95% CI]: 2.62 [1.11-6.19], p = 0.028 and 2.57 [1.25-5.26], p = 0.010, respectively). CONCLUSION: Turkish preschool children with excessive screen time were significantly more likely to have poor psychosocial well-being. Preschool children with behavioral problems should be evaluated for excessive screen time.

Mechanical dissipation via image potential states on a topological insulator surface.

Joule energy loss due to resistive heating is omnipresent in today's electronic devices whereas quantum-mechanical dissipation is largely unexplored. Here, we experimentally observe a suppression of the Joule dissipation in Bi2Te3 due to topologically protected surface states. Instead, a different type of dissipation mechanism is observed by pendulum atomic force microscopy, which is related to single-electron tunnelling resonances into image potential states that are slightly above the Bi2Te3 surface. The application of a magnetic field leads to the breakdown of the topological protection of the surface states and restores the expected Joule dissipation process. Nanomechanical energy dissipation experienced by the cantilever of the pendulum atomic force microscope provides a rich source of information on the dissipative nature of the quantum-tunnelling phenomena on the topological insulator surface, with implications for coupling a mechanical oscillator to the generic quantum material.

A comparative study of oculomotor, trochlear and abducens nerves in Arabian foals.

We investigated the microscopic structure of transverse sections of the oculomotor, trochlear and abducens nerves of Arabian foals using stereological methods. Bilateral nerve pairs from 2-month-old female Arabian foals were analyzed. The tissues were embedded in plastic blocks, then 1 µm thick sections were cut and stained with osmium tetroxide and methylene blue-azure II. Stereology was performed using light microscopy. Morphometry showed that the right and left pairs of nerves were similar. The transverse sectional areas of the oculomotor, trochlear and abducens nerves were 1.93 ± 0.19 mm2, 0.32 ± 0.06 mm2 and 0.70 ± 0.08 mm2, respectively. The oculomotor nerve exhibited a significantly greater number of myelinated axons (16755 ± 1279) and trochlear (2656 ± 494) and the abducens nerves (4468 ± 447). The ratio of the axon diameter to myelinated nerve fiber diameter was 0.58, 0.55 and 0.55 for the oculomotor, trochlear and abducens nerves, respectively. Of the three nerves studied, the abducens nerve exhibited the greatest nerve fiber area, myelin area, nerve and axon diameters, and myelin thickness. The ratio of small myelinated nerve fibers was greatest in the oculomotor nerve.

Crigler-Najjar syndrome type I in a Turkish newborn caused by a novel mutation and Gilbert type genetic defect.

Crigler-Najjar syndrome (CNS), caused by deficiency of bilirubin uridine diphosphate glucuronosyltransferase (UGT) 1A1, is a rare and autosomal recessive inherited disorder characterized by severe unconjugated nonhemolytic hyperbilirubinemia since birth. We present a girl with CNS type I caused by a novel mutation and Gilbert type genetic defect. Gilbert's Syndrome (GS) and CNS type I both involve abnormalities in bilirubin conjugation secondary to deficiency of bilirubin UGT. The combined defects even in benign genetic forms were shown to cause more serious clinical disease. The patient has been treated with daily home-based phototherapy for more than nine months and considered as a candidate for liver transplantation.

Inhibitory effects of acetylsalicylic acid on exocrine pancreatic carcinogenesis.

We investigated short (6 months) and long (12 months) term inhibitory effects of low (200 ppm) and high (400 ppm) dosages of acetylsalicylic acid (aspirin) on exocrine pancreatic carcinogenesis. It is known that exocrine pancreatic carcinogenesis can be detected by the presence of atypical acinar cell foci (AACF) in pancreas. We investigated possible inhibitory effects of acetylsalicylic acid in an azaserine-treated rat model. AACF were produced in rats by injection with azaserine according to previous studies. Our findings showed that the number, volume and diameter of pancreatic AACF were reduced after acetylsalicylic acid application. These observations suggest that acetylsalicylic acid may exert a protective effect against neoplastic development of pancreatic acinar cells in azaserine injected rats. Our findings corroborate reports in the literature concerning the effects of aspirin in reducing neoplastic development.

Frequency and gate voltage effects on the dielectric properties and electrical conductivity of Al∕SiO(2)∕p-Si metal-insulator-semiconductor Schottky diodes.

The dielectric properties and electrical conductivity of Al∕SiO(2)∕p-Si (MIS) Schottky diodes (SDs) in the frequency range of 10 kHz to 10 MHz and the gate voltage range of -2 to 6 V have been investigated in detail using experimental C-V and G∕w-V measurements. Experimental results indicated that the voltage dependence of the real part of the dielectric constant (ɛ') and loss tangent (tan δ) characteristics have a peak at each frequency. The values of ɛ' increase with decreasing frequency and tend to be frequency independent in the negative voltage region. However, the values of the dielectric loss (ɛ″) increase with decreasing frequency at each voltage. In contrast, ɛ' and ɛ″ are almost found to decrease, and the ac electrical conductivity (σ(ac)) and the real part of the electric modulus (M') increase, with increasing frequency. In addition, the imaginary part of the electric modulus (M″) showed a peak that shifts to a higher frequency with increasing applied voltage. It can be concluded that interfacial polarization can more easily occur at low frequencies, and consequently the majority of interface states at the Si-SiO(2) interface contribute to the deviation of the dielectric properties of Al∕SiO(2)∕p-Si (MIS) SDs.

Concomitant trastuzumab with thoracic radiotherapy: a morphological and functional study.

BACKGROUND: The purpose of this study is to elucidate if there is an additive or supra-additive toxic effects of radiotherapy (RT) and trastuzumab (T) on vascular structures when used concomitantly. METHODS: Female Wistar albino rats were treated with either 8 or 15 Gy of thoracic RT. T was applied i.p. with a dose of 6 mg/kg 2 h before RT. Four rats in each arm were killed at 6th h, 21st and 70th days after irradiation and thoracic aorta of each animal was dissected for electron microscopy. In addition, functional studies for evaluating the relaxation and contraction were carried out 21 days after RT. RESULTS: Only 15-Gy RT dose groups showed significant difference in terms of functional deterioration as more contraction than the others (P < 0.05) without any difference between RT and RT + T. However, T produced additional deficit in relaxation when added to RT, which was considered near significant (P: 0.0502). Electron microscopy showed endothelial and subendotelial damage signs in 15-Gy dose groups. T + 15-Gy arm showed more pronounced endothelial cell damage than 15-Gy RT-only arm, 70 days after RT. CONCLUSION: T and high-dose RT may lead to vascular damage that seems at least additive.

Effects of locally applied 5-fluorouracil on the prevention of postmastectomy seromas in a rat model.

BACKGROUND: Seroma formation is the most common complication following mastectomy and axillary dissection (AD). Currently available interventions have aimed at obliterating dead space by inducing fibrosis and through various mechanical methods. Here, 5-fluorouracil (5-FU), used as a sclerosing agent for the prevention of seroma formation, was investigated in a rat mastectomy model. METHODS: 20 rats were divided into two groups (5-FU and control). All rats underwent mastectomy and AD. Immediately following the operation, equal volumes of saline and 5-FU were administered under the surgical flaps. One week after the operation, seroma formation and wound-healing processes were evaluated using histopathological and biochemical investigations. RESULTS: 5-FU did not act as a sclerosing agent, yet it was highly effective in preventing seroma formation. The intensity of acute inflammation, vascularity, as well as leukocyte and fibroblast infiltration, were significantly lower in the 5-FU group than the control; the tissue collagen fractions and total seroma collagen contents were found to be similar between the two groups. CONCLUSIONS: The mechanisms underlying seroma prevention by 5-FU are probably related to a decrease in the inflammation and angiogenesis rather than a local fibrotic process. Seroma formation may be due to a prolonged inflammatory phase of wound healing.

Scanning electron microscopic features of the ovine interdigital sinus.

This article describes the scanning electron microscopic (SEM) features of the ovine interdigital sinus. The lumen was filled with a dense secretory material and quite a number of hairs embedded in the luminal content. For SEM purposes, the sinus was divided into three parts: base, body and neck. At the cut surface, the wall exhibited significant folds which were almost absent in the base, the very short blind end of the sinus. The wall had three layers: epidermis, dermis and fibrous capsule. Stratified epithelium with a prominent keratin layer faced the lumen. The inner surface was similar to the skin surface; however, it was coarser due to folds. The fibrous capsule was composed mainly of dense connective tissue, constituting the outermost layer of the wall. The dermis contained common skin structures including sebaceous glands, hair follicles, arrector pili muscles and apocrine glands. Sebaceous glands appeared as groups of bubbles if they were not collapsed. Apocrine glands generally appeared as a group of coiled tubules. They frequently exhibited apocrine blebs, which is a feature of apocrine secretion. SEM was able to locate some secretory vesicles in the lumen of apocrine tubules which is frequently filled by secretory content. Thus, the apocrine tubules exhibited classical features of apocrine secretion.

The scanning electron and light microscopic structure of bovine tactile hair.

Bovine tactile hairs in skin samples from the lateral side of the upper lip were examined using scanning electron and light microscopy. The root of these hairs has a variable length and is surrounded by a large sinus located between the internal and the external dermal sheath. With a prominent thickness, the external dermal sheath forms the external wall of the tactile hair and contains many nerves some of which extend into trabeculae. Trabeculae projecting from the internal dermal sheath and attaching to the external dermal sheath with two or more branches are present in the entire sinus. The trabeculae are interconnected by connective tissue sheets that support the integrity of the trabecular organization. The sinus surfaces as well as trabeculae are lined by endothelia. As a result, the bovine tactile hair is truly a cavernous type of tactile hair with a well organized microscopic anatomy. Thus, the bovine tactile hair most likely plays an important role in relatively immobile and insensitive bovine lips.

The chordae tendineae of the heart in chicken.

In this study, the chordae tendineae of 10 adult chickens have been investigated by means of scanning electron microscopy (SEM). It has been observed that the diameter of the collagen fibrils on the left side of the heart was greater than those on the right side. The present study has determined that only perichordal and interchordal ligaments are present in the chicken. It was also observed that axial tendons were surrounded by perichordal membrane. Although no difference was evident among the apex of the chordae, differences were observed between the base and apex of the same chordae.

Arterial supply of the pineal gland of Akkaraman sheep.

Arterial vascularisation of the ovine pineal gland was investigated by latex injection preparations of the common carotid artery in 20 adult Akkaraman sheep brains under stereo light microscope. It was observed that the arterial supply comes exclusively from branches of the caudal cerebral artery. The pineal gland was found to contain a rich vascular network. This network also received a few branches from the caudal choroid rami.

Vascularisation of the cerebellar nuclei in Akkaraman sheep.

This study reports an anatomical study of the vascular supply in 20 Akkaraman sheep cerebelli from adult subjects of both sexes. The origin and branching pattern of the cerebellar artery vascularising the cerebellar nuclei were studied by gross dissection and vascular injection. Then dissection was performed and vessels nourishing the cerebellar nuclei were documented. Four bilaterally symmetrical cerebellar nuclei were determined as nucleus lateralis cerebelli, nucleus interpositus lateralis cerebelli, and nucleus interpositus medialis cerebelli and nucleus fastigii from lateral to medial side. It has been previously confirmed that vascularisation of the cerebellar nuclei is carried out by intermediary branches of the rostral cerebellar artery and the caudal cerebellar artery. However, this study has confirmed that the caudal cerebellar artery has no contribution in the vascularisation of the cerebellar nuclei.

Comparison of pure nicotine- and smokeless tobacco extract-induced toxicities and oxidative stress.

The toxicities and oxidative stress-inducing actions of (-)-nicotine and smokeless tobacco extract (STE), containing equivalent amounts of nicotine, were studied. Toxicities were determined by colony formation assays using Chinese hamster ovary (CHO) cells. Results indicated that nicotine is less toxic than smokeless tobacco extract that contained the same amount of nicotine. The generation of reactive oxygen species, following treatment with smokeless tobacco extract and nicotine, was assessed by measurement of changes in glutathione (GSH) and malondialdehyde (MDA) levels. CHO cells (5 x 10(5) cells/5 ml media) were incubated with 4, 0.8, and 0.08 mg of nicotine and STE containing the same amounts of nicotine. All preparations of smokeless tobacco extract significantly decreased GSH levels and increased MDA generation. However, 0.08 mg of nicotine treatment did not result in a significant change in GSH level, and only 4 mg of nicotine were sufficient to increase MDA generation. Addition of free radical scavenging enzymes, superoxide dismutase (SOD) and catalase (CAT), and an intracellular GSH precursor, N-acetyl-L-cysteine (NAC), replenished the GSH levels in nicotine-treated cells. GSH levels in cells exposed to smokeless tobacco extract containing 4 and 0.8 mg nicotine remained significantly lower than the control with the addition of SOD and CAT. However, co-addition of NAC with smokeless tobacco extract preparations returned the GSH levels to the control level. Lactate dehydrogenase (LDH) activities were measured in the media to establish the membrane damage following exposure to smokeless tobacco extract and nicotine. Treatment of cells with 4 mg nicotine caused a significant increase in LDH activity, which was returned to control level in the presence of the antioxidant enzymes and NAC. Smokeless tobacco extract did not change the LDH activity. http://link.springer-ny. com/link/service/journals/00244/bibs/37n4p434.html

N-acetyl-L-cysteine protects against delta-aminolevulinic acid-induced 8-hydroxydeoxyguanosine formation.

5-Aminolevulinic acid (ALA) is a heme precursor that accumulates in acute intermittent porphyria and lead poisoning. It has been shown that ALA induces free radical generation and may cause damage to proteins and DNA. In the present study, the effects of ALA on DNA damage and its prevention by N-acetyl-L-cysteine (NAC) and the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) are investigated. Oxidative damage to DNA was quantitated by measuring the increase in 8-hydroxy-2'-deoxyguanosine (oh8dG) formation. The time-course study demonstrated that ALA causes a linear increase in oh8dG levels in Chinese hamster ovary (CHO) cells. However, direct lead exposure did not cause any measurable increase in oh8dG levels. In the presence of either NAC (1 mM) or antioxidant enzymes (10 u/ml SOD and 10 u/ml CAT), oh8dG levels returned to the corresponding control levels. This suggests a protective role for NAC and the antioxidant enzymes. To determine the effect of ALA on cell proliferation, cell numbers were counted at the end of 24 h of incubation in the presence and absence of ALA at different concentrations. Results showed that levels of ALA up to 5 mM do not inhibit cell proliferation.

Nicotine enantiomers and oxidative stress.

Nicotine affects a variety of cellular processes ranging from induction of gene expression to secretion of hormones and modulation of enzymatic activities. The objective of this study was to characterize the toxicity of nicotine enantiomers as well as their ability to induce oxidative stress in an in vitro model using Chinese hamster ovary (CHO) cells. Colony formation assay has demonstrated that (-)-nicotine is the more toxic of the enantiomers. At 6 mM concentrations, (-)-nicotine was found to be approximately 28- and 19-fold more potent than (+)-, and (+/-)-nicotine (racemic), respectively. Results also indicated that the toxicity of (+/-)-nicotine is higher than that of (+)-nicotine. (-)-Nicotine at a 10 mM concentration substantially decreased glutathione (GSH) levels (46% decrease). In addition, a 3-fold increase in malondialdehyde (MDA) level was evident in cells after exposure to 10 mM (-)-nicotine. Increased lactate dehydrogenase (LDH) activities in the media demonstrated that cellular membrane integrity was disturbed in nicotine treated cells. In the presence of superoxide dismutase (SOD) and catalase (CAT), the LDH activities returned to control value in 24 h with all concentrations of (-)-, (+)-, and (+/-)-nicotine. The decreases in LDH activities in the presence of the radical scavenging enzymes SOD and CAT suggest that membrane damage may be due to free radical generation.

Pro-oxidant effects of delta-aminolevulinic acid (delta-ALA) on Chinese hamster ovary (CHO) cells.

delta-Aminolevulinic Acid (delta-ALA) is a heme precursor accumulated in lead poisoning and acute intermittent porphyria. Although no single mechanism for lead toxicity has yet been defined, recent studies suggest at least some of the lead-induced damage may originate from delta-ALA-induced oxidative stress. The present study was designed to test the hypothesis that delta-ALA accumulation in Chinese hamster ovary (CHO) cells contributes to the cumulative oxidative challenge of lead poisoning as indicated by the oxidative stress parameters glutathione (GSH), glutathione disulfide (GSSG), malondialdehyde equivalents (MDA), and catalase (CAT). It will also examine the possibility that this oxidative challenge can be reversed by treatment with an antioxidant such as N-acetylcysteine (NAC). First in vitro administration of delta-ALA to CHO cells was found to have a concentration-dependent inhibitory effect on colony formation and cell survival. NAC administration was shown to alleviate this inhibition in CHO survival. The oxidative status of CHO cell cultures exposed to increasing concentrations of delta-ALA was then examined. Decreases in GSH levels (P < 0.05) were observed in the delta-ALA-treated cultures as compared to the controls, while GSSG and MDA levels were significantly increased in delta-ALA-treated cells (P < 0.05). CAT activity was not significantly affected. NAC administration concurrent with delta-ALA exposure resulted in GSH and GSSG levels similar to the control levels, while no significant improvement in MDA was observed. These results indicate a state of oxidative stress and suggest that the delta-ALA- induced inhibitory effect on CHO colony formation may be due to its pro-oxidant effect. To assess whether this oxidative challenge would induce antioxidant increases during extended exposure to delta-ALA, CHO cells were exposed to 5 mM delta-ALA for increasing time periods. The GSH and GSSG levels were measured and a rebound effect was observed after 12 h of delta-ALA exposure.