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.

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.

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.

Successful management of Graves' disease in a patient undergoing regular dialysis therapy.

Classic Graves' disease associated with thyroid-stimulating hormone receptor antibodies developed in a woman undergoing regular hemodialysis for uremia from chronic pyelonephritis. Her condition responded well to treatment initially with carbimazole and then an ablative dose of sodium iodide I 131 therapy. To our knowledge this is only the second documented case of hyperthyroidism in a patient with chronic renal failure, and it demonstrates that conventional forms of therapy are efficacious and safe.

Phenylbutazone-induced systemic vasculitis with crescentic glomerulonephritis.

Two patients had phenylbutazone-induced systemic vasculitis syndrome. Both presented with acute oliguric renal failure, and renal biopsies showed severe crescentic glomerulonephritis with marked interstitial inflammatory cell infiltration. Withdrawal of phenylbutazone and treatment with immunosuppressives and plasma exchange led to recovery of renal function in one case.

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.

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.

An overlapping syndrome of IgA nephropathy and lipoid nephrosis.

The authors studied eight cases of IgA nephropathy presenting with nephrotic syndrome. Renal biopsy revealed only mild mesangial proliferation or minor glomerular changes on light microscopic examination but typical features of IgA nephropathy on immunofluorescent and electron microscopic examination. A satisfactory response characterized by correction of hypoalbuminemia, clearance of proteinuria, and an increase of endogenous creatinine clearance occurred with corticosteroid therapy. These cases represent a variant of IgA nephropathy associated with a nephrotic syndrome that resembles lipoid nephrosis in its responsiveness to steroid.

Clostridium difficile-associated colitis in uremic patients.

Five uremic patients managed in a renal unit developed Clostridium difficile-associated colitis. Four cases occurred in a cluster at about the same time. All patients had previously received or were on antibiotic therapy at the onset of diarrhea and one patient was also on oral steroid therapy. Cefotaxime, a third generation cephalosporin was involved in all five cases. All patients had severe diseases with explosive diarrhea and systemic toxicity. The diagnosis was confirmed in all cases by culture of C. difficile and demonstration of high titers of C. difficile cytotoxin in the stool. Histology from rectal biopsy in one patient showed classical pseudomembranous colitis. Response to treatment with vancomycin was generally good though one patient had two relapses. Uremic patients have impaired immune response and intestinal motility and are predisposed to C. difficile infection. Cross-infection can occur and the isolation of affected patients seems prudent.

Diphtheroid peritonitis associated with continuous ambulatory peritoneal dialysis.

Five patients on continuous ambulatory peritoneal dialysis (CAPD) developed peritonitis caused by diphtheroid bacteria. Peritoneal catheter exit site inflammation and/or discharge preceded all cases and relapses were common. Antimicrobial therapy alone failed to eradicate the bacteria and peritoneal catheter removal was required before peritonitis resolved. Laboratory culture of the diphtheroid bacteria was difficult and prolonged incubation was often necessary. Diphtheroid bacteria are important opportunistic pathogens in immunocompromised patients and should be carefully sought for in all cases of culture-negative CAPD-associated peritonitis.

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.

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.

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.

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.

Polyarteritis presenting with thrombocytosis and central retinal vein thrombosis.

We report a case of polyarteritis in a 54 year old woman who presented with marked thrombocytosis and acute blindness in one eye secondary to central retinal vein thrombosis. She also developed bilateral pulmonary infiltrates and renal failure. The diagnosis was confirmed by histological changes in the renal biopsy. Treatment with immunosuppressives, plasma exchange and antiplatelet drugs led to rapid clinical improvement and recovery of renal function and prevented further thromboembolic episodes. Plasma exchange and antiplatelet drugs should be considered in polyarteritis group of systemic vasculitis especially in the presence of thromboembolic complications or thrombocytosis.

Polyarteritis group of systemic vasculitis--new diagnostic criteria.

We have used new diagnostic criteria to define patients with the polyarteritis nodosa (PAN) group of vasculitis. These were the combination of a necrotising glomerulitis without diffuse deposits of immunoglobulins or complement components in a patient presenting with systemic disease and multi-organ involvement. Twenty-two patients who fulfilled these criteria presented to our unit between 1975 and 1982. The diagnosis of PAN was confirmed by traditional histological criteria in eight. We anticipate that the use of these criteria will lead to earlier diagnosis and thereby improve the management of this potentially lethal disorder.