Aerosol delivery and spatiotemporal tissue distribution of hydroxychloroquine in rat lung

Inhalation enables the delivery of drugs directly to the lung, increasing the retention for prolonged exposure and maximizing the therapeutic index. However, the differential regional lung exposure kinetics and systemic pharmacokinetics are not fully known, and their estimation is critical for pulmonary drug delivery. The study evaluates the pharmacokinetics of hydroxychloroquine in different regions of the respiratory tract for multiple routes of administration. We also evaluated the influence of different inhaled formulations on systemic and lung pharmacokinetics by identifying suitable nebulizers followed by early characterization of emitted aerosol physicochemical properties. The salt- and freebase-based formulations required different nebulizers and generated aerosol with different physicochemical properties. An administration of hydroxychloroquine by different routes resulted in varied systemic and lung pharmacokinetics, with oral administration resulting in low tissue concentrations in all regions of the respiratory tract. A nose-only inhalation exposure resulted in higher and sustained lung concentrations of hydroxychloroquine with a lung parenchyma-to-blood ratio of 386 after 1440 min post-exposure. The concentrations of hydroxychloroquine in different regions of the respiratory tract (i.e., nasal epithelium, larynx, trachea, bronchi, and lung parenchyma) varied over time, indicating different retention kinetics. The spatiotemporal distribution of hydroxychloroquine in the lung is different due to the heterogeneity of cell types, varying blood perfusion rate, clearance mechanisms, and deposition of inhaled aerosol along the respiratory tract. In addition to highlighting the varied lung physiology, these results demonstrate the ability of the lung to retain increased levels of inhaled lysosomotropic drugs. Such findings are critical for the development of future inhalation-based therapeutics, aiming to optimize target site exposure, enable precision medicine, and ultimately enhance clinical outcomes.

In Vivo Profiling of a Natural Alkaloid, Anatabine, in Rodents: Pharmacokinetics and Anti-Inflammatory Efficacy

Natural alkaloids, a large class of plant-derived substances, have attracted considerable interest because of their pharmacological activities. In this study, the in vivo pharmacokinetics and anti-inflammatory profile of anatabine, a naturally occurring alkaloid, were characterized in rodents. Anatabine was found to be bioavailable and brain-penetrant following systemic administration. Following intraperitoneal (i.p.) administration (1, 2, and 5 mg/kg), anatabine caused a dose-dependent reduction in carrageenan-induced paw edema in rats; in mice, it inhibited the production of pro-inflammatory cytokines and simultaneously elevated the levels of an anti-inflammatory cytokine in a dose-dependent manner 2 h after lipopolysaccharide challenge. Furthermore, anatabine (∼10 and ∼20 mg/kg/day for 4 weeks; inhalation exposure) had effects in a murine model of multiple sclerosis, reducing neurological deficits and bodyweight loss. Comparative studies of the pharmacokinetics and anti-inflammatory activity of anatabine demonstrated its bioequivalence in rats following i.p. administration and inhalation exposure. This study not only provides the first detailed profile of anatabine pharmacokinetics in rodents but also comprehensively characterizes the anti-inflammatory activities of anatabine in acute and chronic inflammatory models. These findings provide a basis for further characterizing and optimizing the anti-inflammatory properties of anatabine.

Impact of whole-body versus nose-only inhalation exposure systems on systemic, respiratory, and cardiovascular endpoints in a 2-month cigarette smoke exposure study in the ApoE-/- mouse model

Cigarette smoking is one major modifiable risk factor in the development and progression of chronic obstructive pulmonary disease and cardiovascular disease. To characterize and compare cigarette smoke (CS)-induced disease endpoints after exposure in either whole-body (WB) or nose-only (NO) exposure systems, we exposed apolipoprotein E-deficient mice to filtered air (Sham) or to the same total particulate matter (TPM) concentration of mainstream smoke from 3R4F reference cigarettes in NO or WB exposure chambers (EC) for 2 months. At matching TPM concentrations, we observed similar concentrations of carbon monoxide, acetaldehyde, and acrolein, but higher concentrations of nicotine and formaldehyde in NOEC than in WBEC. In both exposure systems, CS exposure led to the expected adaptive changes in nasal epithelia, altered lung function, lung inflammation, and pronounced changes in the nasal epithelial transcriptome and lung proteome. Exposure in the NOEC caused generally more severe histopathological changes in the nasal epithelia and a higher stress response as indicated by body weight decrease and lower blood lymphocyte counts compared with WB exposed mice. Erythropoiesis, and increases in total plasma triglyceride levels and atherosclerotic plaque area were observed only in CS-exposed mice in the WBEC group but not in the NOEC group. Although the composition of CS in the breathing zone is not completely comparable in the two exposure systems, the CS-induced respiratory disease endpoints were largely confirmed in both systems, with a higher magnitude of severity after NO exposure. CS-accelerated atherosclerosis and other pro-atherosclerotic factors were only significant in WBEC.

State-of-the-art methods and devices for the generation, exposure, and collection of aerosols from heat-not-burn tobacco products

Tobacco harm reduction is increasingly recognized as a promising approach to accelerate the decline in smoking prevalence and smoking-related population harm. Potential modified risk tobacco products (MRTPs) must undergo a rigorous premarket toxicological risk assessment. The ability to reproducibly generate, collect, and use aerosols is critical for the characterization, and preclinical assessment of aerosol-based candidate MRTPs (cMRTPs), such as noncombusted cigarettes, also referred to as heated tobacco products, tobacco heating products, or heat-not-burn (HNB) tobacco products. HNB tobacco products generate a nicotine-containing aerosol by heating tobacco instead of burning it. The aerosols generated by HNB products are qualitatively and quantitatively highly different from cigarette smoke (CS). This constitutes technical and experimental challenges comparing the toxicity of HNB aerosols with CS. The methods and experimental setups that have been developed for the study of CS cannot be directly transposed to the study of HNB aerosols. Significant research efforts are dedicated to the development, characterization, and validation of experimental setups and methods suitable for HNB aerosols. They are described in this review, with a particular focus on the Tobacco Heating System version 2.2. This is intended to support further studies, the objective evaluation and verification of existing evidence, and the development of scientifically substantiated HNB MRTPs.

State-of-the-art methods and devices for generation, exposure, and collection of aerosols from e-vapor products

E-vapor products (EVP) have become popular alternatives for cigarette smokers who would otherwise continue to smoke. EVP research is challenging and complex, mostly because of the numerous and rapidly evolving technologies and designs as well as the multiplicity of e-liquid flavors and solvents available on the market. There is an urgent need to standardize all stages of EVP assessment, from the production of a reference product to e-vapor generation methods and from physicochemical characterization methods to nonclinical and clinical exposure studies. The objective of this review is to provide a detailed description of selected experimental setups and methods for EVP aerosol generation and collection and exposure systems for their in vitro and in vivo assessment. The focus is on the specificities of the product that constitute challenges and require development of ad hoc assessment frameworks, equipment, and methods. In so doing, this review aims to support further studies, objective evaluation, comparison, and verification of existing evidence, and, ultimately, formulation of standardized methods for testing EVPs.

[Definition and diagnosis of acute-on-chronic liver failure: new knowledge and implication]

Acute-on-chronic liver failure (ACLF) is a common critical and severe syndrome in patients with chronic liver diseases in China and other countries in the Asia-Pacific region. In recent years, both the Eastern and Western experts have defined ACLF as a new type of liver disease manifesting as a high 28-day mortality rate (>30%) and extensive systematic inflammatory response. ACLF has become a hot topic in the field of liver diseases. This article reviews the research advances in the definition and etiological spectrum of ACLF and discusses the inspirations of such new knowledge for future research.

Investigation of the influence of keloid-derived keratinocytes on fibroblast growth and proliferation in vitro

Keloids are disfiguring, proliferative scars that represent a pathological response to cutaneous injury. The overabundant extracellular matrix formation, largely from collagen deposition, is characteristic of these lesions and has led to investigations into the role of the fibroblast in its pathogenesis. Curiously, the role of the epidermis in extracellular matrix collagen deposition of normal skin has been established, but a similar hypothesis in keloids has not been investigated. The aim of this study was to investigate the influence of keloid epithelial keratinocytes on the growth and proliferation of normal fibroblasts in an in vitro serum-free co-culture system. A permeable membrane separated two chambers; the upper chamber contained a fully differentiated stratified epithelium derived from the skin of excised earlobe keloid specimens, whereas the lower chamber contained a monolayer of normal or keloid fibroblasts. Both cell types were nourished by serum-free medium from the lower chamber. Epithelial keratinocytes from five separate earlobe keloid specimens were investigated. Four sets of quadruplicates were performed for each specimen co-cultured with normal fibroblasts or keloid-derived fibroblasts. Controls consisted of (1) normal keratinocytes co-cultured with normal fibroblasts, and (2) fibroblasts grown in serum-free media in the absence of keratinocytes in the upper chamber. Fibroblasts were indirectly quantified by 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay, with results confirmed by DNA content measurement, at days 1 and 5 after the co- culture initiation.Significantly, increased proliferation was seen in fibroblasts co-cultured with keloid keratinocytes, as compared with the normal keratinocyte controls at day 5 (analysis of variance, p < 0.001). These results strongly suggest that the overlying epidermal keratinocytes of the keloid may have an important, previously unappreciated role in keloid pathogenesis using paracrine or epithelial-mesenchymal signaling.

Diathermy and alcohol skin preparations - a potential disastrous mix

Disinfectant solutions with high concentrations of alcohol are used in many operating theatres as skin preparation. We present two cases of burns as a result of accidental ignition of the solution and list precautionary measures for the use of these solutions.

Multiple tumour presentation of trichilemmal carcinoma

Trichilemmal carcinoma is a rare skin tumour occurring in the sun-exposed areas of the elderly. It originates from the external root sheath of the hair follicle and is the malignant form of the trichilemmoma. Clinically, it may be mistaken for a squamous cell carcinoma, basal cell carcinoma, nodular melanoma or keratoacanthoma. It is distinct from the proliferating trichilemmal tumour. Trichilemmal carcinoma is usually a solitary lesion and an extensive literature search revealed no previously reported cases of multiple tumour presentation. We describe a case of trichilemmal carcinoma arising from three distinct sites in the same patient and discuss the differential diagnoses, histological features and probable aetiology of this rare tumour.

Double papilla of Vater: a rare anatomic anomaly observed in endoscopic retrograde cholangiopancreatography

A double papilla of Vater, with separate openings for the bile duct and the pancreatic duct, is a rare anatomic anomaly observed in endoscopic retrograde cholangiopancreatography (ERCP). We report the case of a 45-year-old Chinese man with obstructive jaundice due to common bile duct stones and gallbladder stones. During ERCP, a double papilla of Vater with separate drainage for the bile duct and the pancreatic duct was observed. As the anatomy was unusual, no sphincterotomy was performed, but a biliary stent was inserted. Subsequently, the patient underwent cholecystectomy and exploration of the common bile duct. On the 15th postoperative day, he was asymptomatic and was discharged. Common bile duct-Pancreatic duct.

Phyllodes tumour: an update of 40 cases

This is a retrospective study of 40 cases of phyllodes tumour treated at the National University Hospital since 1985. The mean age of presentation was 37.8 years, with a range of 15 to 58 years [standard deviation (SD) 11.22 years]. Ninety per cent of the patients were premenopausal. The mean size of tumours was 52 mm, with a range of 10 to 220 mm. Preoperative diagnosis was correct in only five patients, the lesion most commonly being mistaken as a fibroadenoma. Initial surgical treatment was by simple excision in 80% of cases. Histologically, the ratio of benign, intermediate and malignant tumours was 82.5%, 12.5% and 5% respectively. Recurrences occurred in only four patients (10%), all of whom were initially treated by simple excision. The diagnosis of phyllodes tumour continues to be difficult even with newer modalities of preoperative investigations, resulting in simple excision as initial treatment of these tumours. Expectant follow-up should be continued for these patients, with wide excision of future recurrences.

Management of concomitant maxillofacial, cervical spine and laryngeal trauma--case reports

Three cases are presented to stress important points in the diagnosis and management of concomitant maxillofacial, cervical spine and laryngeal trauma. Emergency tracheostomy to control airway, immediate rigid fixation of maxillofacial fractures, early computed tomographic (CT) scans to evaluate the extent of laryngeal and cervical spine injury and the early repair of laryngeal injury will provide better aesthetic and functional results.

The genetic basis of malignant hyperthermia

Malignant hyperthermia (MH) susceptibility remains the commonest cause of death owing to general anaesthesia. In humans, genetically predisposed to MH, anaesthesia can induce skeletal muscle rigidity, hypermetabolism and hyperthermia, which if not immediately reversed can lead to tissue injury and death. In swine, the corresponding condition leads to stress-induced deaths and devalued meat products. Aberrant behaviour in the calcium (Ca2+) release channel (the ryanodine receptor) of skeletal muscle sarcoplasmic reticulum has been implicated in the cause of both the porcine and human syndromes by biochemical, physiological and molecular genetic analysis. In swine, a single mutation in the ryanodine receptor gene (RYR1) can account for all cases of MH in all breeds, but a series of different RYR1 mutation are uncovered in human families with MH. In addition, the lack of linkage between MH and RYR1 in some families indicates a heterogeneous genetic basis for the human MH.

Congenital extraskeletal Ewing's sarcoma of the face: a case report

This is the first reported case of congenital extraskeletal Ewing's sarcoma (EES) in the head and neck region. The tumor arose from the medial aspect of the right lower eyelid and rapidly increased in size despite surgery and chemotherapy. Accurate histologic diagnosis is emphasized, and the differential diagnosis, pathology, and treatment are discussed.

The solitary thyroid nodule revisited

A series of 195 clinically solitary thyroid nodules is presented and compared with a matching series reported a decade ago. Changes in the pattern of presentation, preoperative diagnosis and options of operative management are highlighted. Although the pattern of presentation has not changed significantly over the last decade, there was a shift noted towards reliance on fine needle aspiration for preoperative diagnosis. The false negative rate was two percent in this series and there were no false positives. There was also a shift towards more conservative surgery in the form of "nodulectomies" in the present series compared to the previous one. The incidence of malignancy in this series was 10.2 percent.

Changing patterns in the treatment of early breast cancer: a historical perspective and a review of changing local trends

Over the past 50 years, a variety of surgical procedures have been advocated for the treatment of operable breast cancer, ranging from local excision to supraradical mastectomy. Today, the surgical treatment of breast cancer remains highly contentious. We review the historical development of breast cancer surgery and analyse the available evidence supporting conservative procedures. We also express our opinions on the treatment of early breast cancer and illustrate the changing patterns of surgery with our experience at National University Hospital.

Transareolar dye-injection microdochectomy

Single-duct microdochectomy is described for use in patients with bloody or serosanguinous nipple discharge arising from a single duct in the breast. Because most such cases are caused by benign, intraductal papillomata, the technique used in removing the offending ductal system should be fully diagnostic, adequately therapeutic, and cosmetically acceptable. A technique is described that is used in 40 consecutive patients with good diagnostic, therapeutic, and cosmetic result. The procedure itself combines techniques and principles of plastic and reconstructive surgery such as minimal tissue trauma, use of anatomical tissue planes, bloodless-field surgery, and microdissection.

Solubilities of trace copper and lead species and the complexing capacity of river water in the Linggi River Basin

Chemical forms of copper and lead in river water of the Linggi River Basin have been fractionated into ASV labile, moderately labile, slowly labile, and inert metal species, based on a previously proposed scheme. Free (hydrated) metal ions were identified by a potentiometric method using an ion selective electrode. Speciation results showed that the soluble copper and lead species occurred mainly in the moderately labile and slowly labile fractions. The speciation results are primarily interpreted in terms of organic interaction due to agricultural based and light industries, and urban discharges. The measured metal complexing capacity (MCC) of the samples reveals consistency of the results with the nature of the discharge. MCC correlates reasonably well with the value from the permanganate test on the river water. In general, the speciation pattern was found to be consistent with the findings of other workers.

Some aspects of breast cancer in Singapore--a review of 306 cases

A retrospective study of 306 cases of carcinoma breast in Singaporean patients managed at the University Department of Surgery, Singapore General Hospital was made, based on all available case notes, pathology report forms, operation record books, Cancer Registry Notification Forms, and data obtained from the Registry of Births and Deaths. These cases had their initial histological diagnosis made between 1970 to 1978. Basic data like age distribution, sex distribution and racial distribution of our cases are presented. Aspects of breast cancer like stage at time of diagnosis and 5- and 10-year survival figures are also presented. The crude five-year survival for all 306 cases was 56% and the crude 10-year survival for 223 cases was 22%. Survival for small lesions (T1, or less than 2 cm) was 90% at five years and 68% at ten years, a rate comparable with most centres in the world.

The rat groin flap as an experimental model in microsurgery

The value of the rat groin flap in microsurgical experiments is discussed. It provides the practising microsurgeon, whatever his specialty, the opportunity to work on vessels ranging from 0.4 mm to 2.0 mm in diameter as well as on small nerves. The single, long, microvascular pedicle of this flap enables numerous experimental procedures to be performed. Most important of all, long term patency of the vessels after anastomosis can be assessed by observing changes in the flap. Rat groin flaps have been used in microsurgery for evaluating techniques of end-to-end and end-to-side anastomoses, testing microvascular auto-and allografts, studying the delay phenomenon in flap surgery, evaluating and comparing the effects of various vasodilator drugs on microvessels and for assessing the effects of avulsion and tension forces on blood vessels and nerves. These aspects are described and discussed.

Mandibular ameloblastoma in Singapore--a 10 year review

This paper reviews 30 cases of mandibular ameloblastoma seen and managed in the Singapore General Hospital over a 10 year period from 1976 to 1985 inclusive. Data on age and sex distribution, mode of presentation, presenting symptoms, size of tumour at time of presentation, radiological features at time of diagnosis, method of treatment and post-operative complications are discussed. There was no case of local recurrence in the 28 cases that were surgically managed. The importance of adequate local excision is emphasised. This paper also compares our local data with that of equivalent studies made in Thailand (Far East), Sweden (Europe) and Nigeria (Africa). An interesting rare case of malignant mandibular ameloblastoma is included in this study.

The "wrap-around" end-to-side anastomosis for micro-vessels

A new technique of end-to-side microvascular anastomosis is described. Using the rat groin flap model this technique was used to anastomose the superficial epigastric artery to the femoral artery. It proved successful with a 100% patency rate in 15 successive animals. Three flaps developed complications unrelated to the anastomosis which necessitated termination of the experiment after 3 days, but the remaining 12 anastomoses were functioning well when examined after 4 weeks.

The solitary thyroid nodule

213 clinically solitary nodules were analysed. Their clinical pattern, diagnostic problems, pathological varieties and surgical management have been assessed. 9.9% of the nodules were malignant in this series.