Efficiency droop in zincblende InGaN/GaN quantum wells.

The decrease in emission efficiency with increasing drive current density, known as 'droop', of c-plane wurtzite InGaN/GaN quantum wells presently limits the use of light-emitting diodes based on them for high brightness lighting applications. InGaN/GaN quantum wells grown in the alternative zincblende phase are free of the strong polarisation fields that exacerbate droop and so were investigated by excitation-dependent photoluminescence and photoreflectance studies. Polarisation-resolved measurements revealed that for all excitation densities studied the emission from such samples largely originates from similar microstructures or combinations of microstructures that form within the quantum well layers. Emission efficiency varies significantly with excitation at 10 K showing that non-radiative recombination processes are important even at low temperature. The onset of efficiency droop, as determined by photomodulated reflection measurements, occurred at a carrier density of around 1.2 × 1020 cm-3 - an order of magnitude greater than the value reported for a reference wurtzite quantum well sample using the same method. The high carrier density droop onset combined with the much shorter carrier lifetime within zincblende InGaN/GaN quantum wells indicate they have the potential to effectively delay efficiency droop when used in GaN based light-emitting diodes. However, the material quality of the quantum well layers need to be improved by preventing the formation of microstructures within these layers, and the importance of the role played by non-radiative centres in the QW layer needs to be elucidated, to fully realise the material's potential.

DNA mismatch repair system expression in salivary gland tumors: A Systematic Review.

BACKGROUND: The DNA mismatch repair (MMR) system serves as a sophisticated guardian of the precise functioning of the human genome. Dysregulation within this system is linked to the oncogenesis process. Reduced expression of MMR system proteins identified in salivary gland tumors (SGTs) suggests an increased risk of tumoral occurrence. This study aims to analyze the expression of MMR proteins in SGTs and discuss the relevance of this association to the development of these neoplasms. MATERIAL AND METHODS: This review was conducted following the PRISMA guidelines and was registered in PROSPERO (CRD42023465590). A comprehensive search of the PubMed/MEDLINE, Web of Science, Scopus, Embase, and ProQuest (non-peer reviewed platform) was performed to answer the question "Do DNA MMR system proteins exhibit expression in SGTs?". The methodological quality of the selected studies was assessed using the JBI's Critical Appraisal Tool. RESULTS: A total of 142 patients with benign SGTs and 84 with malignant SGTs were included in this review. The literature analysis showed a notable reduction in the expression of DNA MMR system proteins (hHMS2, hMLH1, hMSH3 and hMSH6) in the percentage of marked cells. CONCLUSIONS: The reduction in the expression of the DNA MMR system proteins suggests an interesting correlation with the development of malignant and benign SGTs. Nevertheless, further investigations are warranted to better clarify the precision of measuring biomarker protein expression.

Linfangioma Oral en Paciente con Síndrome Koolen de Vries: Presentación de Caso y Revisión de Literatura

Los linfangiomas son tumores benignos hamartomatosos de los vasos linfáticos, originadas de un secuestro del saco linfático y agrandados por un inadecuado drenaje a la falta de comunicación con los canales linfáticos centrales o a la secreción excesiva de células de revestimiento. La incidencia de estos tumores en el sistema linfático es baja con una frecuencia de 1,2 a 2,8/1.000 en niños, sin predilección por sexo. En el territorio maxilofacial se pueden distinguir tres tipos de linfangioma: linfangioma simple, linfangioma cavernoso e higroma quístico o linfangioma quístico. Clínicamente estas lesiones se presentan como masas de tejido blando indoloras y de crecimiento lento. Su aspecto clínico depende de la extensión de la lesión. Diversos métodos de tratamiento para el linfangioma han sido reportados en la literatura, siendo la escisión quirúrgica la indicada, principalmente cuando estructuras vitales no están involucradas en la lesión. En este artículo se presenta un caso de una paciente femenina de 13 años con un aumento de volumen en el bermellón del labio superior, con antecedente de síndrome Koolen De Vries, a la cual se le realizó la exéresis de la lesión.

Lymphangiomas are benign hamartomatous tumors of the lymphatic vessels, originating from a sequestration of the lymphatic sac and enlarged by inadequate drainage, lack of communication with the central lymphatic channels or excessive secretion of lining cells. The incidence of these tumors in the lymphatic system is low, with a frequency of 1.2 to 2.8/1000 in children, with no predilection for sex. Three types of lymphangioma can be distinguished in the maxillofacial territory: simple lymphangioma, cavernous lymphangioma, and cystic hygroma or cystic lymphangioma. Clinically, these lesions present as painless, slow-growing soft tissue masses. Their clinical appearance depends on the extent of the lesion. Various treatment methods for lymphangioma have been reported in the literature, with surgical excision being indicated mainly when vital structures are not involved in the lesion. This article presents a case of a 13-year-old female patient with an increase in volume in the vermilion of the upper lip, with a history of Koolen De Vries syndrome, in which the excision of the lesion was performed.

Systematic review and evidence gap mapping of biomarkers associated with neurological manifestations in patients with COVID-19.

OBJECTIVE: This study aimed to synthesize the existing evidence on biomarkers related to coronavirus disease 2019 (COVID-19) patients who presented neurological events. METHODS: A systematic review of observational studies (any design) following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and the Cochrane Collaboration recommendations was performed (PROSPERO: CRD42021266995). Searches were conducted in PubMed and Scopus (updated April 2023). The methodological quality of nonrandomized studies was assessed using the Newcastle‒Ottawa Scale (NOS). An evidence gap map was built considering the reported biomarkers and NOS results. RESULTS: Nine specific markers of glial activation and neuronal injury were mapped from 35 studies published between 2020 and 2023. A total of 2,237 adult patients were evaluated in the included studies, especially during the acute phase of COVID-19. Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) biomarkers were the most frequently assessed (n = 27 studies, 77%, and n = 14 studies, 40%, respectively). Although these biomarkers were found to be correlated with disease severity and worse outcomes in the acute phase in several studies (p < 0.05), they were not necessarily associated with neurological events. Overall, 12 studies (34%) were judged as having low methodological quality, 9 (26%) had moderate quality, and 9 (26%) had high quality. CONCLUSIONS: Different neurological biomarkers in neurosymptomatic COVID-19 patients were identified in observational studies. Although the evidence is still scarce and conflicting for some biomarkers, well-designed longitudinal studies should further explore the pathophysiological role of NfL, GFAP, and tau protein and their potential use for COVID-19 diagnosis and management.

Múltiples Dientes Supernumerarios en Paciente Pediátrico No Sindrómico. Una Revisión de la Literatura y Presentación de Caso Clínico / Multiple Supernumerary Teeth In A Non-Syndromic Pediatric Patient. A Review Of The Literature and Presentation of a Clinical Case

Aquellos casos en que se excede la fórmula dentaria normal primaria de 20 dientes o definitiva de 32 dientes se conocen como dientes supernumerarios o hiperodoncia. Los supernumerarios se pueden presentar de manera única o múltiple y de forma heteromórfica o eumórfica. El supernumerario más prevalente es el mesiodens, se da más en hombres, en dentición permanente y en el maxilar. Su etiología no está confirmada, pero puede deberse a una hiperactividad de la lámina dental. El tratamiento varía de acuerdo a cada paciente según si está afectando a la dentición normal o no y el desarrollo que tengan las estructuras dentarias. El siguiente reporte de caso habla de un paciente de 6 años, no sindrómico, en donde se presentó con un mesiodens erupcionado y se encontraron más supernumerarios gracias a la radiografía complementaria.

Those cases in which the primary normal dental formula of 20 teeth or the final one of 32 teeth is exceeded are known as supernumerary teeth or hyperdontia. The supernumeraries can be presented in a single or multiple way and in a heteromorphic or eumorphic way. The most prevalent supernumerary is the mesiodens, it occurs more in men, in the permanent dentition and in the maxilla. Its etiology is not confirmed, but it may be due to hyperactivity of the dental lamina. The treatment varies according to each patient depending on whether it is affecting the normal dentition or not and the development of the dental structures. The following case report talks about a 6-year-old, non- syndromic patient, who presented with an erupted mesiodens and more supernumeraries were found thanks to the complementary radiography.

Disentangling the Impact of Point Defect Density and Carrier Localization-Enhanced Auger Recombination on Efficiency Droop in (In,Ga)N/GaN Quantum Wells.

The internal quantum efficiency of (In,Ga)N/GaN quantum wells can surpass 90% for blue-emitting structures at moderate drive current densities but decreases significantly for longer emission wavelengths and at higher excitation rates. This latter effect is known as efficiency "droop" and limits the brightness of light-emitting diodes (LEDs) based on such quantum wells. Several mechanisms have been proposed to explain efficiency droop including Auger recombination, both intrinsic and defect-assisted, carrier escape, and the saturation of localized states. However, it remains unclear which of these mechanisms is most important because it has proven difficult to reconcile theoretical calculations of droop with measurements. Here, we first present experimental photoluminescence measurements extending over three orders of magnitude of excitation for three samples grown at different temperatures that indicate that droop behavior is not dependent on the point defect density in the quantum wells studied. Second, we use an atomistic tight-binding electronic structure model to calculate localization-enhanced radiative and Auger rates and show that both the corresponding carrier density-dependent internal quantum efficiency and the carrier density decay dynamics are in excellent agreement with our experimental measurements. Moreover, we show that point defect density, Auger recombination, and the effect of the polarization field on recombination rates only limit the peak internal quantum efficiency to about 70% in the resonantly excited green-emitting quantum wells studied. This suggests that factors external to the quantum wells, such as carrier injection efficiency and homogeneity, contribute appreciably to the significantly lower peak external quantum efficiency of green LEDs.

Aclimatación a la alta temperatura y tolerancia al calor (TL50) en 6 variedades de Chenopodium quinoa / High temperature acclimation and termotolerance (TL50) in 6 varieties of Chenopodium quinua

Se estudió la capacidad de aclimatación de 6 variedades de Chenopodium quinoa Willd. (Kancolla, Salcedo, Ccoito, Negra collana, Pasancalla e Illpa) a alta temperatura. Las plantas de quinua se obtuvieron a partir de semillas, las que crecieron en macetas, en un sombreadero, hasta el estado fenológico de 6 hojas verdaderas. Estas fueron expuestas a un tratamiento por calor en una cámara de crecimiento con termostato a 34/32 °C día/noche (D/N) por 3 días y a baja intensidad luminosa. Las no aclimatadas crecieron en las mismas condiciones pero a la temperatura de 22/20 °C D/N. La tolerancia a la alta temperatura se determinó exponiendo discos de hojas a diferentes tiempos (8, 16, 32 y 64 min) a 50 °C (baño maría), midiendo la termoestabilidad de la membrana celular, por la pérdida electrolitos utilizando un conductimetro. El grado de termotolerancia fue hallado según el TL50(tiempo letal al 50% de daño). Los resultados muestran que las variedades Pasancalla e Illpa presentaron capacidad de aclimatación, la variedad más termotolerante fue la variedad Illpa TL50= 64 min cuando fue aclimatada y la más sensible fue la variedad Pasancalla TL50= 8 min cuando no fue aclimatada. También se observó que el porcentaje de daño celular se incrementó a medida que el tiempo de exposición a la alta temperatura fue mayor

The capacity of acclimatization at high temperature of 6 varieties (Kancolla, Salcedo, Ccoito, Negra collana, Pasancalla and Illpa) of Chenopodium quinoa Willd was studied. Quinoa plants were obtained from seeds, which grew in pots, in a grennhouse, until the phenological stage of 6 true leaves. These were exposed to a heat treatment in a growth chamber with a thermostat at 34/32 °C day/night (D/N) for 3 days and at low light intensity. The non-acclimated plants grew under the same conditions but at temperature of 22/20 °C D/N. The tolerance to high temperature was determined by exposing leaf discs at different times (8, 16, 32 and 64 min) at 50 °C (warm bath), measuring the thermostability of the cell membrane trough the loss of electrolytes with a conductimeter. The degree of thermotolerance was found according to the TL50 (time lethal to 50% of damage). The results showed that the varieties Pasancalla and Illpa presented acclimatization capacity, the most thermotolerant variety was the variety Illpa TL50 = 64 min when it was acclimatized and the most sensitive was Pasancalla TL50 = 8 min when it was not acclimatized. It was also observed that the percentage of cell damage increased as the exposure time to the high temperature was higher.

Caracterización de las sospechas de reacciones adversas a medicamentos herbolarios notificadas a la Unidad Coordinadora Provincial de Farmacovigilancia Santiago de Cuba / Characterization of suspected adverse reactions to herbal medicines reported to the Provincial Coordinating Unit of Pharmacovigilance Santiago de Cuba

Se desarrolló un estudio descriptivo, transversal y retrospectivo en el Sistema de Farmacovigilancia a la terapia herbolaria en la provincia Santiago de Cuba desde el año 2004 hasta el año 2008, para caracterizar las sospechas de reacciones adversas a este grupo de medicamentos y que fueron notificadas a la Unidad Coordinadora Provincial. Los resultados se analizaron a través de la estadística correlacional, obteniéndose que la hipotensión, la epigastralgia y los mareos constituyeron las sospechas de reacciones adversas más frecuentes y los medicamentos herbolarios más incidentes fueron el extracto fluido de la corteza de mango en tableta, el jarabe de aloe al 50 por ciento y la tintura de ajo al 20 por ciento, predominaron las sospechas de reacciones adversas probables y leves y al clasificarlas teniendo en cuenta su frecuencia de aparición, incidieron las reacciones raras(AU)

A cross sectional and retrospective study was performed in the Pharmacovigilance System to herbal therapy at the providence of Santiago de Cuba from 2004 to 2008, in order to characterize the suspected adverse reactions and to notify to the Provincial Coordinating Unit. The results were analyzed through statistical correlation, obtaining that hypotension, epigastric pain and dizziness were the more frequent suspected adverse drug reactions, where the highest incidence was observed on the herbal medicines containing the fluid extract of the mango bark in tablet, the aloe 50 percent syrup and the garlic 20 percent tincture, the predominant adverse drug reactions were mild and when classified based on their frequency, they were rare reactions(AU)

The short-term effects of diammine silver fluoride on tooth sensitivity: a randomized controlled trial.

Tooth sensitivity is a common clinical problem. This multi-center randomized clinical trial assessed the effectiveness and safety of topical diammine silver fluoride. From two sites (Lima and Cusco, Peru), 126 adults with at least one tooth sensitive to compressed air were randomly assigned to either the experimental treatment or sterile water, and pain was assessed by means of a 100-mm visual analogue scale at 24 hours and 7 days. The diammine silver fluoride reduced pain at 7 days at both sites. At the Lima site, the average change in pain scores between baseline and day 7 for the silver fluoride group was -35.8 (SD = 27.7) mm vs. 0.4 (SD = 16.2) mm for the control group (P < 0.001). In Cusco, the average change in pain scores for the silver fluoride group was -23.4 (SD = 21.0) mm and -5.5 (18.1) mm for the control group (P = 0.002). No tissue ulceration, white changes, or argyria was observed. A small number of participants in the silver fluoride group experienced a mild but transient increase in erythema in the gingiva near the tooth. No changes were observed in the Gingival Index. We concluded that diammine silver fluoride is a clinically effective and safe tooth desensitizer.

Ocular linguatuliasis in Ecuador: case report and morphometric study of the larva of Linguatula serrata.

Linguatula serrata is a pentastomid, a cosmopolitan parasite belonging to the Phylum Pentastomida. Humans may act as an intermediate or accidental definitive host of this parasite, manifesting the nasopharyngeal or visceral form, with the latter having been described more frequently. The occurrence of ocular linguatuliasis is extremely rare, but it has been reported in the United States and Israel. The objective of the present paper was to report the first case of ocular linguatuliasis in Ecuador and to extend the morphologic study of L. serrata by morphometric analysis. The patient studied was a 34-year old woman from Guayaquil, Ecuador who complained of ocular pain with conjunctivitis and visual difficulties of two-months duration. Biomicroscopic examination revealed a mobile body in the anterior chamber of the eye. The mobile body was surgically removed. The specimen was fixed in alcohol, cleared using the technique of Loos, stained with acetic carmine, and mounted on balsam between a slide and a coverslip. It was observed with stereoscopic and common light microscopes in combination with an automatic system for image analysis and processing. The morphologic and morphometric characteristics corresponded to the third-instar larval form of L. serrata. To our knowledge, ocular linguatuliasis has not been previously described in South America, with this being the first report for Ecuador and South America. The present study shows that computer morphometry can adequately contribute both to the morphologic study and to the systematic classification of Pentastomids, and L. serrata in particular.

Lipids covalently bound to keratins of mouse mammary epithelial cells.

Keratin polypeptides obtained from mouse mammary epithelial cells (MMEC) were found to be modified by covalent attachment of lipids. MMEC in primary culture were incubated in 3H-palmitate and treated with 1.5M KCl/1% Triton X-100 to obtain a cytoskeletal (CS) fraction containing primarily keratin and actin filaments. After exhaustive extraction to remove labeled lipids, the CS proteins were separated by gel electrophoresis, and the labeled 46 kD (K18) and 55 kD (K8) keratin polypeptides were excised, subjected to acid hydrolysis and the chloroform-soluble products were resolved on thin layer chromatography. For both keratins, covalently bound lipid included major peaks which co-chromatographed with fatty acid standards. Also, unlabeled lipid resolving with fatty acid standards was found covalently bound to both keratins. The results are discussed in terms of keratin-lipid-membrane interactions.

Covalent binding of lipids to cytoskeletal proteins of mouse mammary epithelial cells.

Cytoskeletal proteins obtained from mouse mammary epithelial cells (MMEC) were found to be modified by covalent attachment of lipids. Primary cultures of MMEC were incubated in the presence of 3H-palmitate for 4 h. A cytoskeletal (CS) fraction was prepared by treatment of the cells with 1.5M KCl and 1% Triton X-100. The residual material, consisting primarily of keratin and actin filaments was exhaustively (10-20 rounds, including sonications) extracted with chloroform/methanol to remove non-covalently bound labeled lipids. The CS protein was then acid-hydrolyzed and the chloroform-soluble products subjected to thin layer chromatography (TLC). Two-thirds of the covalently bound radiolabel appeared as a very hydrophobic peak on a TLC system optimized for separation of neutral lipids. Ten percent separated into 4-5 peaks on a polar lipid TLC system. A small amount of label was traced to fatty acid-like components. Autoradiography of two-dimensional gels indicated that all the CS proteins resolvable by Coomassie blue staining were also radiolabeled. The results are discussed in terms of CS-lipid-membrane interactions.

Comparative growth of normal and malignant mouse mammary epithelium cultured serum-free on a biomatrix from preadipocytes.

Growth of normal and malignant mouse mammary epithelial cells (MMEC) on a biomatrix of substrate-attached material from 3T3-L1 preadipocytes was evaluated to devise culture conditions that are suitable for transformation studies but do not involve embedding cells in a gel. The biomatrix was prepared as described by Levine and Stockdale, and serum-free medium contained bovine serum albumin, insulin, progesterone, prolactin, and linoleic acid. Each cell type produced a distinctive pattern of colony architecture in this culture system. Cells from virgin mice (vMMEC) usually formed elaborate, three-dimensional structures resembling ducts and alveoli; cells from pregnant mice (pMMEC) grew as flat monolayers; and tumor cells grew in multilayered clusters. Cell growth was monitored by an assay for succinate dehydrogenase. Similar growth rates were found through Day 8 in cultures of vMMEC and D2 carcinoma cells. Growth of vMMEC slowed thereafter, whereas tumor cells typically continued growing through Day 14 to 18. Increase in cell number during 18 days in culture was 3-, 7-, 9-, and 11-fold for cells from pregnant and virgin mice, BALB/cfC3H and D2 carcinomas, respectively. The percent cells in S phase on Day 2 of culture was 9% for pMMEC, 4 to 11% for BALB/cfC3H tumor cells, 20% for vMMEC, and 24% for D2 tumor cells. Thus, this culture system promotes extended growth of MMEC and offers several advantages over embedding cells in a collagen gel. It may therefore be applicable to in vitro transformation studies with MMEC.

Lipids noncovalently associated with keratins and other cytoskeletal proteins of mouse mammary epithelial cells in primary culture.

Lipids noncovalently associated with cytoskeletal (CS) proteins of mouse mammary epithelial cells (MMEC) grown in primary culture were analyzed. A CS fraction, prepared by subjecting MMEC to 1.5 M KCl and 1% Triton X-100 in phosphate buffered saline (pH 7.4), was extracted 4-6 times with chloroform/methanol. Thin-layer chromatography (TLC) indicated that in comparison to whole cell lipid extracts, CS lipids consisted mostly of neutral lipids, especially triacylglycerols and, possibly cholesteryl esters. TLC analysis of chloroform/methanol CS extracts prepared from MMEC that had been incubated 4 h in [3H]palmitate revealed similar results, with the majority of label appearing in triacylglycerols and other neutral lipids. By autoradiography of sodium dodecyl sulfate polyacrylamide gels, all of the major CS proteins appeared labelled. The major regions of autoradiographic density of the gel were excised, the protein solubilized, and the lipids extracted and subjected to TLC. Most of the radiolabel appeared at the origin and ion front and resolved as neutral lipids. In contrast, keratins of 54-55 kDa and 46 kDa appeared to be associated noncovalently with a higher ratio of polar lipids (possibly phospholipids) to nonpolar (neutral lipids). Very little radioactivity, mostly neutral lipid, was associated with actin. A previously unidentified CS component of 30 kDa had primarily noncovalently bound neutral lipid. The results are discussed in terms of the apparent interactions of keratin filaments with the plasma membrane, nuclear envelope and cytoplasmic organelles.

Free and liposomal doxorubicin treatment of intraperitoneal colon 26 tumor: therapeutic and pharmacologic studies.

Intraperitoneal (i.p.) chemotherapy is being investigated as an adjunct to surgery to kill residual cancer cells, inhibit cancer cell seeding, local recurrence, and metastases for ovarian, gastric, and colon cancers. In this report, the therapeutic effects of Doxorubicin (Dox) and liposome-entrapped Dox (Dox-Lip) against i.p. mouse colon 26 (C26) tumor were compared. It was found that Dox-Lip was less toxic than Dox after i.p. administration in non-tumor bearing animals. I.P. Dox and Dox-Lip significantly inhibited the growth of C26 tumor when the treatment was initiated 1 day after tumor cell inoculation, but both administration forms were ineffective against well-established (8-day) tumors. Multiple dose schedules did not improve the therapeutic response. Dox-Lip was not therapeutically superior to Dox at equal doses or at approximately equi-toxic doses. In addition, the relative retention of Dox and Dox-Lip in the peritoneal cavity and their plasma pharmacokinetics were investigated. It was found that Dox levels in the peritoneal cavity were maintained for longer periods after i.p. Dox-Lip was administered. However, the results show that maintenance of elevated drug levels in the peritoneal cavity does not necessarily lead to increased therapeutic effects.

Toxicity of non-drug-containing liposomes for cultured human cells.

The effects of non-drug-containing liposomes of different compositions and sizes on the proliferation of nine cancer-derived and one normal cultured human cell lines were determined. Stearylamine- and cardiolipin-containing liposomes were toxic (ID50) at 200 microM liposomal lipid concentrations or less, whereas phosphatidylglycerol- and phosphatidylserine-containing liposomes were toxic in the range 130-3000 microM. Phosphatidylcholine or dipalmitoylphosphatidylcholine liposomes were not toxic at 3000-4000 microM. In general, small liposomes were more toxic than large ones. The results indicate that there are wide variations in toxicity of non-drug-containing liposomes for cultured human cells. The potential for nonspecific toxicity due to the liposomes themselves should be carefully considered if human administration of drug-containing liposomes is to be done.

Characterization of liposomes prepared using a microemulsifier.

A new type of device can prepare liposomes continuously, in large quantities and with excellent aqueous space capture efficiency. At initial lipid concentration of 300 mumol/ml these liposomes capture approx. 75% of cytosine arabinoside used as an aqueous space marker. Liposome size can be reduced by increasing the number of times the preparations are recycled through the microemulsifier. Liposomes less than 0.1 micron in diameter, as shown by electron microscopy, can be made easily. Liposomes prepared at 300 mumol/ml, composed of phosphatidylglycerol/phosphatidylcholine/cholesterol in a 0.1:0.4:0.5 molar ratio leaked less than 1% of entrapped cytosine arabinoside (Ara-C) at 4 degrees C, and less than 10% Ara-C at 37 degrees C plus serum, over a 48 h period. These liposomes could be useful for a number of applications including diagnostics, therapeutics and model membrane studies.