Rapid antigen test during a COVID-19 outbreak in a private hospital in Hong Kong.

INTRODUCTION: In response to two nosocomial clusters of coronavirus disease 2019 (COVID-19) in our hospital, we adopted a series of strict infection control measures, including regular rapid antigen test (RAT) screening for high-risk patients, visitors, and healthcare workers. We evaluated the diagnostic performance of a locally developed RAT, the INDICAID COVID-19 Rapid Antigen Test (Phase Scientific, Hong Kong), using respiratory samples from both symptomatic and asymptomatic individuals. METHODS: Real-time reverse-transcription polymerase chain reaction (rRT-PCR)-confirmed deep throat saliva (DTS) and pooled nasopharyngeal swab and throat swab (NPS/TS) samples collected from 1 November to 30 November 2020 were tested by INDICAID. Screening RATs were performed on asymptomatic healthcare workers during a 16-week period (1 December 2020 to 22 March 2021). RESULTS: In total, 20 rRT-PCR-confirmed samples (16 DTS, four pooled NPS/TS) were available for RAT. Using the original sample, RAT results were positive in 17/20 samples, indicating 85% sensitivity (95% confidence interval [CI]=62.11%-96.79%). Negative RAT results were associated with higher cycle threshold (Ct) values. For samples with Ct values <25, the sensitivity was 100%. Of the 49 801 RATs collected from healthcare workers, 33 false positives and one rRT-PCR-confirmed case were detected. The overall specificity was 99.93% (95% CI=99.91%-99.95%). The positive and negative predictive values were 2.94% (95% CI=2.11%-4.09%) and 100%, respectively. CONCLUSION: The INDICAID COVID-19 RAT demonstrated good sensitivity for specimens with high viral loads and satisfactory specificity for low-risk, asymptomatic healthcare workers.

Multiparameter optimisation of a magneto-optical trap using deep learning.

Machine learning based on artificial neural networks has emerged as an efficient means to develop empirical models of complex systems. Cold atomic ensembles have become commonplace in laboratories around the world, however, many-body interactions give rise to complex dynamics that preclude precise analytic optimisation of the cooling and trapping process. Here, we implement a deep artificial neural network to optimise the magneto-optic cooling and trapping of neutral atomic ensembles. The solution identified by machine learning is radically different to the smoothly varying adiabatic solutions currently used. Despite this, the solutions outperform best known solutions producing higher optical densities.

Development of a geometrically accurate and adaptable finite element head model for impact simulation: the Naval Research Laboratory-Simpleware Head Model.

This study demonstrates a novel model generation methodology that addresses several limitations of conventional finite element head models (FEHM). By operating chiefly in image space, new structures can be incorporated or merged, and the mesh either decimated or refined both locally and globally. This methodology is employed in the development of a highly bio-fidelic FEHM from high-resolution scan data. The model is adaptable and presented here in a form optimised for impact and blast simulations. The accuracy and feasibility of the model are successfully demonstrated against a widely used experimental benchmark in impact loading and through the investigation of potential brain injury under blast overpressure loading.

Identification of a tumor suppressive critical region mapping to 3p14.2 in esophageal squamous cell carcinoma and studies of a candidate tumor suppressor gene, ADAMTS9.

A gene critical to esophageal cancer has been identified. Functional studies using microcell-mediated chromosome transfer of intact and truncated donor chromosomes 3 into an esophageal cancer cell line and nude mouse tumorigenicity assays were used to identify a 1.61 Mb tumor suppressive critical region (CR) mapping to chromosome 3p14.2. This CR is bounded by D3S1600 and D3S1285 microsatellite markers. One candidate tumor suppressor gene, ADAMTS9, maps to this CR. Further studies showed normal expression levels of this gene in tumor-suppressed microcell hybrids, levels that were much higher than observed in the recipient cells. Complete loss or downregulation of ADAMTS9 gene expression was found in 15 out of 16 esophageal carcinoma cell lines. Promoter hypermethylation was detected in the cell lines that do not express this gene. Re-expression of ADAMTS9 was observed after demethylation drug treatment, confirming that hypermethylation is involved in gene downregulation. Downregulation of ADAMTS9 was also found in 43.5 and 47.6% of primary esophageal tumor tissues from Hong Kong and from the high-risk region of Henan, respectively. Thus, this study identifies and provides functional evidence for a CR associated with tumor suppression on 3p14.2 and provides the first evidence that ADAMTS9, mapping to this region, may contribute to esophageal cancer development.

The use of the Minimum Data Set. Home Care in a case management project in Hong Kong.

130 hospital-discharged elderly patients received our comprehensive assessment by using a Chinese Minimum Data Set-Home Care (MDS-HC). Our case manager developed and implemented care plans with reference to the computer-generated Clients Assessment Protocols. Results showed that the MDS-HC was sensitive to identify elderly persons' holistic needs, and helpful in formulating all-inclusive care plans.

Focal lobular spermatogenesis and pubertal acceleration associated with ipsilateral Leydig cell hyperplasia.

Leydig cell tumors of the testis are the underlying cause in about 10% of the cases of precocious puberty in boys. Leydig cell hyperplasia is a less well-characterized cause, with an undocumented frequency. We describe a boy with precocious puberty associated with ipsilateral testicular enlargement and focal Leydig cell hyperplasia with spermatogenesis limited to the local adjacent testicular tissue.

Incidence of complicated healing and osteoradionecrosis following tooth extraction in patients receiving radiotherapy for treatment of nasopharyngeal carcinoma.

A group of 43 patients requiring tooth extraction after radiotherapy for nasopharyngeal carcinoma (NPC) was studied retrospectively to determine the incidence of post-extraction complications. It was found that because of the method used in the delivery of radiation, extraction of maxillary posterior teeth resulted in the greatest risk of complications (28.9 per cent), including a 10.5 per cent risk of osteoradionecrosis (ORN). Based on the findings, a protocol was established for the dental care of such patients. It was concluded that when extraction of maxillary posterior teeth was necessary, prophylactic antibiotics were not sufficient to prevent the complication of delayed healing. The risk of ORN was 10.5 per cent within the field of maximal radiation dose. Hyperbaric oxygen may be the better choice of preventive measures. However, in view of the low risk of ORN, wholesale prescription of hyperbaric oxygen therapy may not be indicated. An additional patient who had tooth extraction two weeks prior to radiotherapy was included to show that if adequate time for wound healing was not allowed, ORN could develop.

High-performance liquid chromatography analysis of oxidized and reduced pyridine dinucleotides in specific brain regions.

An ultrasensitive HPLC method has been developed for measuring NADP+, NADPH, NAD+, and NADH. A simple, rapid reaction of the oxidized nucleotides with cyanide in basic solution leads to two stable fluorescent products and allows all four nucleotides to be separated and quantitated on one chromatogram. Furthermore, only one extraction is needed, rather than prior procedures which require one acid extraction (for oxidized species) and one basic extraction (for reduced species). This method is particularly useful in quantitating pyridine dinucleotides in rodent brain, where no current method is adequate to quantitate the small amounts contained in various brain regions. The assay is sensitive enough to measure individual brain regions down to 10 mg of tissue. Due to the involvement of NAD(P)H enzymatic systems in combating oxidative stress it is important to be able to assess levels regionally in brain diseases.

Administration of drugs by infusion pumps in palliative medicine.

A retrospective study was carried out in 100 adult patients with advanced malignant disease. They were given subcutaneous continuous infusions of medication for symptom relief. The drugs were administered through a butterfly needle inserted subcutaneously in the anterior chest wall using a battery-operated infusion pump. The indications for using this technique were inability to swallow due to deteriorating general condition, oesophageal obstruction, intestinal obstruction, severe nausea and vomiting, terminal dyspnoea and poor pain control with oral opiates. All patients received morphine; other drugs administered through the syringe driver included hyoscine, metoclopramide, cyclizine, dexamethasone and midazolam. Ninety-four patients continued subcutaneous infusion until death. The mean duration of treatment was 9.1 days. The treatment was well tolerated by the patients and controlled their symptoms satisfactorily in the great majority. The use of continuous subcutaneous infusion via a syringe driver gives good symptom control. In the last days of life when the patients have difficulty tolerating oral medication, continuous subcutaneous infusion is a superior alternative to frequent intermittent parenteral injections.

Redox cycling of MPP+: evidence for a new mechanism involving hydride transfer with xanthine oxidase, aldehyde dehydrogenase, and lipoamide dehydrogenase.

MPP+ is redox active in the presence of cytochrome P450 reductase and induces the formation of O2.- and HO(.). In this study, we report the redox cycling capability of MPP+ with additional enzymes and with UV photolysis detected through ESR techniques. The treatment of MPP+ with UV light resulted in the production of HO. trapped as a spin adduct. Two of the enzymes examined in this study, xanthine oxidase and aldehyde dehydrogenase, produced O2.- in the presence of substrate. However, when MPP+ was added to the incubations, the radical trapped by DMPO was HO(.). This indicates that MPP+ redox cycles in the presence of these two enzymes or UV light, which produces HO.. Our data also suggest that MPP+ is reduced by lipoamide dehydrogenase. MPP+ stimulated the oxidation of reduced nicotinamide adenine dinucleotide (NADH) by the enzyme at concentrations between 2 mM and 8 mM of MPP+. Higher concentrations of MPP+ inhibited lipoamide dehydrogenase. MPP+ appears to be redox active with a number of redox enzymes. The mechanism involved may be hydride transfer from the enzymes to MPP+, rather than a direct single-electron reduction.

MPP+ and MPDP+ induced oxygen radical formation with mitochondrial enzymes.

MPP+ has been reported to inhibit reduced nicotinamide adenine dinucleotide (NADH) dehydrogenase in mitochondria, which results in the formation of O2(.-). The current report demonstrates that H2O2 and HO. are also products of MPP+ interaction with NADH dehydrogenase. It is possible that MPP. formation precedes the formation of some of these active oxygen species. Reducing equivalents for radical formation come from NADH. MPP+ may be capable of interacting with submitochondrial particles at a site other than the rotenone site, which results in some formation of oxygen radicals. Plasma amine oxidase incubations with MPDP+ resulted in O2.- H2O2, and perhaps HO. formation. This is probably due to MPP. formation from the oxidation of MPDP+. This study presents new findings that indicate the potential importance of oxygen radical formation in mitochondria during MPTP toxicity.

Cognitive-behavioural group therapy for Hong Kong Chinese adults with mental health problems.

Ninety-one Chinese in the community, aged between 18 and 45, with mental health problems ranging from mild to moderate degree, were treated by cognitive behavioural group therapy (CBGT) for a period of 3 months. All subjects were assessed on multiple measures at 4 time points: screening, pre-treatment (after 3 months), post-treatment and at 3-month follow-up. Attendance was good. A standard practice manual was developed to ensure consistent treatment by 2 group workers. After controlling for the placebo effect in the waiting period, treatment effect was demonstrated which was sustained after a three month period. The all-round improvement included a decrease in psychiatric symptoms, improvement in self-assessment, better and more social activities and being more able to cope with problems. In terms of psychiatric diagnosis, depressed subjects gained the most benefit and personality disorder subjects the least. Parents seemed to benefit more than non-parents.

Sclerosing peritonitis complicating prolonged use of chlorhexidine in alcohol in the connection procedure for continuous ambulatory peritoneal dialysis.

Sclerosing peritonitis (SP) is an uncommon but serious complication of CAPD with various suggested etiologies. We have documented 14 cases of SP in 18 patients who had used chlorhexidine in alcohol (ChA) in the connection procedure for CAPD. Thirteen died. Nine of the 14 patients had been transferred to hemodialysis or renal transplantation, yet all still developed symptoms of SP within a few months after transfer - even the 5 who were originally asymptomatic. The main symptoms of SP were peritoneal ultrafiltration failure, exudative bloody ascites and intestinal obstruction. They presented at around 5 years (30-80 months) after commencement of CAPD. Most deaths were related to intestinal obstruction. Four other patients with a comparable duration of ChA exposure were continued on CAPD with the Travenol Spike System (TSS), without further exposure to ChA. They were all asymptomatic of SP after 9-12 months. Comparing the 2 groups of asymptomatic patients, those transferred to TSS had a much better outcome after 9 months than those transferred to HD or renal transplantation (P = 0.0476). We suggest that ChA is the main cause of SP in our patients and that continuing CAPD without further exposure to ChA is a better alternative than stopping CAPD to prevent the progression of SP.

Coupling of mitochondrial metabolism and protein synthesis in heart mitochondria.

Although much is now known with regard to the processes of mammalian mitochondrial gene expression, relatively little is known concerning the quantitative regulation of this pathway in response to hormones or other physiological stimuli. In this paper the potential coupling of mitochondrial metabolism to mitochondrial protein synthesis was investigated and the concentration of nucleotides and substrates for optimal translation in isolated rat heart mitochondria was determined. It was demonstrated that optimal isolated heart mitochondrial protein synthesis required the presence of an oxidizable substrate. Of the substrates tested, glutamate (20 mM) supported translation best followed by malate, succinate, and alpha-ketoglutarate, whereas pyruvate supported synthesis poorly. Unlike other recent mammalian mitochondrial systems, the presence of an oxidizable substrate was required for translation even in the presence of medium ATP and an exogenous energy-generating system. Mitochondrial translation also required the presence of adenine nucleotide that could be added as ADP or ATP; however, ATP added above 0.5 mM became progressively inhibitory. As a result, synthesis was supported significantly better by ATP synthesized by the system from added ADP, than by ATP added directly to the system. However, if the phosphorylation of ADP was prevented by limiting the phosphate concentration, ADP itself strongly inhibited mitochondrial protein synthesis. This inhibition appeared to be closely related to the energy charge of the system rather than to absolute levels of ADP, indicating for the first time that mitochondrial translation, like its cytoplasmic counterpart is regulated by energy charge. Last, this system did not require the inhibition of guanine nucleotide or exogenous energy-generating systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitochondrial protein synthesis during thyroxine-induced cardiac hypertrophy.

The goal of this paper was to determine the effects of 3,5,3'-triiodothyronine (T3)-thyroxine-induced cardiac hypertrophy on the rates of synthesis of mitochondrial proteins by both the cytoplasmic and mitochondrial protein synthesis systems and to compare the results with total protein synthesis and cardiac enlargement. Daily injections of T3-thyroxine in the rat resulted in a 25% increase in the growth of the ventricle compared with controls. The cytoplasmic synthesis of both mitochondrial and total proteins as measured in the isolated perfused heart was stimulated by T3-thyroxine injection to a peak of 155 and 146%, respectively, of vehicle-injected controls after 3 days of hormone treatment. This peak was followed by a gradual decline in stimulation in total protein synthesis to 132% of control by 9 days of injection, whereas the decline in stimulation of cytoplasmic synthesis of mitochondrial proteins was significantly steeper, falling to 119% of vehicle control. The rate of protein synthesis within the mitochondrial compartment was also measured during the time course of T3-thyroxine-induced hypertrophy. These rates were measured in an isolated intact heart mitochondrial protein synthesis system described and characterized in the companion papers [E. E. McKee, B. L. Grier, G. S. Thompson, and J. D. McCourt. Am. J. Physiol. 258 (Endocrinol. Metab. 21): E492-E502, 1990; and E. E. McKee, B. L. Grier, G. S. Thompson, A. C. F. Leung, and J. D. McCourt. Am. J. Physiol. 258 (Endocrinol. Metab. 21): E503-E510, 1990]. Rates of mitochondrial protein synthesis were dramatically stimulated by T3-thyroxine injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Sclerosing peritonitis complicating continuous ambulatory peritoneal dialysis with the use of chlorhexidine in alcohol.

Sclerosing peritonitis (SP) is an uncommon but serious complication of CAPD with various suggested etiology. We have documented 14 cases of SP in 18 CAPD patients using chlorhexidine in alcohol (ChA) in the connection procedure; 13 died. Nine of the 14 patients had been transferred to haemodialysis or renal transplantation, yet all still developed symptoms of SP within a few months after transfer even though 5 of them were originally asymptomatic. The main symptoms of SP were peritoneal ultrafiltration failure, exudative bloody ascites and intestinal obstruction. They present at around 5 years (30-80 months) after commencement of CAPD. Four other patients with a comparable duration of ChA exposure were continued on CAPD with a Travenol Spike System (TSS) without further exposure to ChA. They were all asymptomatic of SP after 9-12 months. Comparing the 2 groups of asymptomatic patients at 9 months after transfer, those transferred to TSS have a much better outcome than those transferred to HD or renal transplantation (P = 0.0476). We concluded that ChA is the main cause of SP in our patients and continuing CAPD without further exposure to ChA is a better alternative than stopping CAPD in preventing the progression of SP.